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+
+
+![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**
+
+**J.101**
+
+**(ex CMTT.720)**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**(06/90)**
+
+**TELEVISION AND SOUND TRANSMISSION**
+
+---
+
+**MEASUREMENT METHODS AND TEST  
+PROCEDURES FOR TELETEXT SIGNALS**
+
+**ITU-T Recommendation J.101**
+
+(Formerly Recommendation ITU-R CMTT.720)
+
+---
+
+# 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 J.101 (formerly Recommendation ITU-R CMTT.720) was elaborated by the former ITU-R Study Group CMTT. See Note 1 below.
+
+# --- 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 Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector (ITU-R).
+
+Conforming to a joint decision by the World Telecommunication Standardization Conference (Helsinki, March 1993) and the Radiocommunication Assembly (Geneva, November 1993), the ITU-R Study Group CMTT was transferred to ITU-T as Study Group 9, except for the satellite news gathering (SNG) study area which was transferred to ITU-R Study Group 4.
+
+2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+# **MEASUREMENT METHODS AND TEST PROCEDURES FOR TELETEXT SIGNALS** (1990)
+
+The CCIR,
+
+# **CONSIDERING**
+
+- (a) that Report 956, Appendix I to Part 1, provides conceptual definitions to proposed data signal parameters;
+- (b) that Report 969 is intended to identify measurement methods and test procedures for checking the impairment of special signals resulting from transmission over television circuits;
+- (c) that operational measurements on teletext signals need no special test signals, because they can be made on the normal teletext lines;
+- (d) that automatic measurement of teletext signals suits the requirements of operational staff and makes the analysis of results easier;
+- (e) that the definitions given in this Recommendation may be applicable to other data services,
+
+## **UNANIMOUSLY RECOMMENDS,**
+
+that, when measuring equipment is used to make measurements on teletext signals, the definitions used in quantifying the parameters should be those given in Annex I.
+
+# **ANNEX I**
+
+## **1. Introduction**
+
+The need for each of the measurements described in this Recommendation (and possibly other measurements) will depend on the type of plant in use and the policy of the administrations.
+
+No special test signals are necessary to meet the requirements of this Recommendation.
+
+The definitions of parameters were specifically designed to meet the requirements of automatic measuring equipment. They are also suitable for manual measurements.
+
+To reduce the influence of non-linear distortions the signal shall be bandlimited prior to measurement to a frequency between the upper limit of the television system and the teletext clock frequency.
+
+Due to the random nature of the teletext signals, the results will exhibit some fluctuation between successive measurements.
+
+## **2. Definition of terms**
+
+This section defines terms which are used in § 3 to define the measurement parameters.
+
+### **2.1 *Mean value of clock run-in***
+
+The mean value of clock run-in is defined as the mean level of the clock run-in waveform excluding the first two bits.
+
+### **2.2 *All-zeros level***
+
+The all-zeros level is the level resulting from a continuous stream of “zero” pulses. For measuring purposes the all-zeros level is defined as the mean level of the back porch within the nominal duration of the colour burst.
+
+---
+
+<sup>1)</sup> Formerly Recommendation ITU-R CMTT.720.
+
+### 2.3 All-ones level
+
+The all-ones level is the level resulting from a continuous stream of “one” pulses. For measuring purposes the all-ones level is defined as twice the mean value of clock run-in minus the all-zeros level.
+
+### 2.4 Basic amplitude
+
+The basic amplitude is the difference between the all-ones level and the all-zeros level.
+
+### 2.5 Nominal teletext signal amplitude
+
+The nominal teletext signal amplitude is defined as a fixed percentage of the luminance bar amplitude and represents the ideal binary “1” amplitude in any teletext system (Fig. 1). If no luminance bar signal is present, the nominal value of the luminance bar signal is used.
+
+*Note* – The luminance bar amplitude is defined in Recommendation 569. The relationship of the nominal teletext signal amplitude to the luminance bar amplitude is defined in Recommendation 653.
+
+![Figure 1: Teletext parameters. A waveform diagram showing signal levels and timing parameters. The diagram includes a 'Basic amplitude' measurement between a '0' and a '1' level. It also shows 'Waveform overshoots' on the rising and falling edges. A 'Peak-to-peak amplitude' is indicated for a rectangular pulse. On the right, the 'White level' and 'Black level' are marked, with the 'Nominal teletext signal amplitude' shown as the difference between them.](a30a7877bf2f45b837a9382e22067ad0_img.jpg)
+
+Figure 1: Teletext parameters. A waveform diagram showing signal levels and timing parameters. The diagram includes a 'Basic amplitude' measurement between a '0' and a '1' level. It also shows 'Waveform overshoots' on the rising and falling edges. A 'Peak-to-peak amplitude' is indicated for a rectangular pulse. On the right, the 'White level' and 'Black level' are marked, with the 'Nominal teletext signal amplitude' shown as the difference between them.
+
+FIGURE 1 – Teletext parameters
+
+d01-sc
+
+### 2.6 Timing reference
+
+The timing reference for each line is a uniform sequence of timing instants whose timing is derived only from the clock run-in of that line excluding the first two bits.
+
+The timing of these instants is such that they coincide with the average timing of the points where the clock run-in crosses the mean value defined in § 2.5.
+
+### 2.7 Sampling instants for decoding margin
+
+The sampling instants for decoding margin are half way between the timing instants defined in § 2.6.
+
+## 3. Definition of parameters
+
+### 3.1 Basic amplitude error
+
+This parameter is defined as the difference between the basic amplitude and the nominal teletext signal amplitude expressed as a percentage of the latter. In terms of abbreviations in Fig. 1 the basic amplitude error is:
+
+$$\frac{E - D}{D} \times 100\%$$
+
+### 3.2 *Peak-to-peak amplitude*
+
+The peak-to-peak amplitude is defined as the sum of basic amplitude zero overshoots and ones overshoots. It is expressed as a percentage of the basic amplitude (see Fig. 1).
+
+### 3.3 *Decoding margin*
+
+The decoding margin is defined as the difference between the highest "0" bit level and the lowest "1" bit level measured at the sampling instants for a bit error ratio of  $10^{-3}$ . The difference is expressed as percentage of the basic amplitude.
+
+### 3.4 *Number of run-in bits*
+
+This parameter counts the number of the "1" and "0" run-in bits present at the start of the teletext waveform prior to the framing code. The result will be always an even number because a "0" bit follows every "1" run-in bit. The counting starts with the first bit with amplitude exceeding the mean value of the clock run-in.
+
+### 3.5 *Data timing*
+
+In teletext System B the data timing is defined as the time difference between the peak of the penultimate "1" run-in bit and the line time datum (see Report 624). In teletex System A the data timing is defined as the time difference between the leading edge of the data signal and the line time datum (see Fig. 2).
+
+![Diagram illustrating data timing for teletext System A and System B. The diagram shows a waveform with a 'Line time datum' marked by a dot. A 'Colour burst' is shown as a shaded area. The 'Data timing (teletext System A)' is indicated by a horizontal arrow from the line time datum to the leading edge of the data signal. The 'Data timing (teletext System B)' is indicated by a horizontal arrow from the line time datum to the peak of the penultimate '1' run-in bit. The 'Timing reference (penultimate run-in bit)' is marked by a vertical dashed line. The waveform includes a 'Clock run-in' section followed by a 'Framing code' section.](bc04d002fc79e8a3637b1552ac3361e6_img.jpg)
+
+The diagram shows a composite video signal waveform. On the left, a vertical line marks the 'Line time datum'. A shaded region represents the 'Colour burst'. To the right of the burst, the waveform transitions into a digital signal. Two horizontal arrows indicate 'Data timing': one for 'teletext System A' starting at the line time datum and ending at the leading edge of the data, and another for 'teletext System B' starting at the line time datum and ending at the peak of the penultimate '1' run-in bit. A vertical dashed line marks the 'Timing reference (penultimate run-in bit)'. The digital signal is divided into 'Clock run-in' and 'Framing code' segments.
+
+Diagram illustrating data timing for teletext System A and System B. The diagram shows a waveform with a 'Line time datum' marked by a dot. A 'Colour burst' is shown as a shaded area. The 'Data timing (teletext System A)' is indicated by a horizontal arrow from the line time datum to the leading edge of the data signal. The 'Data timing (teletext System B)' is indicated by a horizontal arrow from the line time datum to the peak of the penultimate '1' run-in bit. The 'Timing reference (penultimate run-in bit)' is marked by a vertical dashed line. The waveform includes a 'Clock run-in' section followed by a 'Framing code' section.
+
+FIGURE 2 – *Data timing*
+
+d02-sc
+
+# BIBLIOGRAPHY
+
+CROLL, M. G. [1977] Ceefax measurement techniques. BBC Research Department Report RD 1977/6.
+
+DEAN, A. and HUTT, P.R. [September, 1980] NEMESIS – Numerical eye measuring equipment for surveillance of insertion signals. Proc. Eighth International Broadcasting Convention (IBC 80). IEE Conf. Publ. No. 191.
+
+## *CCIR Documents*
+
+[1986-90]: CMTT/34, CMTT/207 (Germany (Federal Republic of)).
\ No newline at end of file
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+
+
+**ITU-T**
+
+**J.1010**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+(09/2016)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Conditional access and protection – Exchangeable  
+embedded conditional access and digital rights  
+management solutions
+
+---
+
+**Embedded common interface for exchangeable  
+CA/DRM solutions; Use cases and requirements**
+
+Recommendation ITU-T J.1010
+
+
+
+# Recommendation ITU-T J.1010
+
+## Embedded common interface for exchangeable CA/DRM solutions; Use cases and requirements
+
+## Summary
+
+Recommendation ITU-T J.1010 specifies use cases and requirements for exchangeable, embedded conditional access/digital rights management (CA/DRM) solutions, enabling customer premises equipment (CPE), which are capable of receiving broadcast and broadband content, to download CA/DRM clients under a trusted environment. By utilizing downloadable multi-CA/DRM service, entitled consumers can consume broadcast and broadband content, which is controlled by DRM and/or conditional access (CA) systems, even though a CPE does not have a required content-related CA/DRM client available by downloading it from a trusted source into various types of CPEs including set-top-boxes (STBs), smart TVs, PCs, smart phones and/or smart tablets.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T J.1010   | 2016-09-02 | 9           | <a href="http://handle.itu.int/11.1002/1000/12772">11.1002/1000/12772</a> |
+
+## Keywords
+
+CA/DRM, exchangeable embedded common interface, retail CPE.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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 .....                                              | 1    |
+| 3.1 Terms defined elsewhere .....                                | 1    |
+| 3.2 Terms defined in this Recommendation.....                    | 1    |
+| 4 Abbreviations and acronyms .....                               | 2    |
+| 5 Conventions .....                                              | 2    |
+| 6 Requirements for exchangeable embedded CA/DRM solutions .....  | 3    |
+| 6.1 General remarks.....                                         | 3    |
+| 6.2 Generic requirements.....                                    | 4    |
+| 6.3 Versatility related requirements .....                       | 5    |
+| 6.4 Practicability related requirements .....                    | 5    |
+| 6.5 ECI Client Swap related requirements .....                   | 5    |
+| 6.6 ECI System Security related requirements.....                | 6    |
+| Annex A – Use Cases.....                                         | 8    |
+| A.1 Use case 1 .....                                             | 8    |
+| A.2 Use case 2 .....                                             | 8    |
+| A.3 Use case 3 .....                                             | 9    |
+| A.4 Use case 4 (Trusted third party (TTP) related use case)..... | 9    |
+| Bibliography.....                                                | 10   |
+
+# Introduction
+
+Service and content protection realized by conditional access (CA) and digital rights management (DRM) are essential in the rapidly developing area of digital broadcast and broadband, including content, services, networks and customer premises equipment (CPE), to protect business models of content owners, network operators and PayTV operators. While conceptually CA focuses on mechanisms to access protected content distributed by a service provider over a network, DRM originally describes type and extent of the usage rights, according to the subscriber's contract.
+
+PayTV operators have established digital TV platforms, which implement standards for basic functions, extended with proprietary elements. Most CA and DRM systems used for classical digital broadcasting, IPTV or new OTT (over-the-top) services capture consumer premises equipment by binding it with proprietary security related elements. As a result, consumer premises equipment configured for use in network or platform A cannot be used in network or platform B or vice versa. Thus, the consumer electronics (CE) market for digital TV is still fragmented, as specifications differ not only per country, but also per platform. Detachable CA/DRM modules only offer a partial solution: the modules are again proprietary to the CA/DRM system, they are not cheap either, and they are used primarily for cable or satellite TV and are not usable in modern-type equipment such as tablets due to lack of appropriate physical interfaces.
+
+Currently implemented solutions, whether embedded or as detachable hardware, result in "Lock-in" effects. This seriously restricts the freedom of many players in digital multimedia content markets. Due to technological advances, innovative, software-based CA/DRM solutions become feasible. Maximizing interoperability while maintaining a high level of security, they promise to meet upcoming demands in the market, allow for new businesses, and broaden consumer choice.
+
+It is in consumers' interest that they are able to continue using the CPEs they bought e.g., after a move or a change of network provider or even utilize devices for services of different commercial video portals. This can only be achieved by interoperability of CPEs regarding CA and DRM, based on an appropriate security architecture. Further fragmentation of the market for CPEs can only be prevented and competition encouraged by ensuring a consumer-friendly and context-sensitive exchangeability of CA and DRM systems.
+
+# Recommendation ITU-T J.1010
+
+## Embedded common interface for exchangeable CA/DRM solutions; Use cases and requirements
+
+# 1 Scope
+
+The object of this Recommendation is a set of basic requirements for an exchangeable, embedded common interface, in order to download any necessary CA/DRM system to CPE. The download process is operated under a trusted environment and enables the consumption of protected content delivered via broadcast and/or broadband connections with various types of terminal equipment in line with the acquired content rights of the end-user. This Recommendation is one in a series of Recommendations, specifying the whole ECI eco-system.
+
+# 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. The following referenced documents are necessary for the application of the present document.
+
+- [ETSI GS ECI 001-1] ETSI GS ECI 001-1: 2014, *Embedded Common Interface (ECI) for exchangeable CA/DRM solutions (ECI); Part 1: Architecture, Definitions and Overview.*
+- [ETSI GS ECI 001-2] ETSI GS ECI 001-2: 2014, *Embedded Common Interface (ECI) for exchangeable CA/DRM solutions; Part 2: Use cases and requirements.*
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+None.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 embedded common interface (ECI):** Architecture and system to be specified in the ETSI ISG "Embedded CI", which allows the development and implementation of software-based swappable ECI clients in customer premises equipment (CPE) and thus provides interoperability of CPE devices with respect to ECI.
+
+**3.2.2 embedded common interface client (ECI client):** Implementation of a CA/DRM client which is compliant with the planned Embedded CI specifications. Note that it is the software module in a CPE which provides all means to receive, in a protected manner, a consumer's entitlements and rights concerning the content that is distributed by a content distributor or operator. It also receives the conditions under which a right or an entitlement can be used by the consumer, and the keys to decrypt the various messages and content. An Embedded CI client may have an associated smart card.
+
+**3.2.3 embedded common interface (ECI) host:** Hardware and software system of a CPE, which covers ECI related functionalities and has interfaces to an ECI Client. Note that the ECI host is one part of the CPE firmware.
+
+**3.2.4 protected content:** All kinds of protected media, in particular A/V and associated metadata, delivered to the customer application either via linear or non-linear delivery means.
+
+**3.2.5 software container:** Set of software interfaces to the host and to the client, which strictly separates the CA/DRM client from the host. The provisioning of the interfaces enables the exchangeability of the CA/DRM clients.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|        |                                              |
+|--------|----------------------------------------------|
+| AES    | Advanced Encryption Standard                 |
+| CA     | Conditional Access                           |
+| CA/DRM | Conditional Access/Digital Rights Management |
+| CE     | Consumer Electronics                         |
+| CPE    | Customer Premises Equipment                  |
+| CSA    | Common Scrambling Algorithm                  |
+| DECE   | Digital Entertainment Content Ecosystem      |
+| DRM    | Digital Rights Management                    |
+| DVB    | Digital Video Broadcasting                   |
+| ECI    | Embedded Common Interface                    |
+| IP     | Internet Protocol                            |
+| IPTV   | TV using the Internet Protocol               |
+| OMA    | Open Mobile Access                           |
+| OTT    | Over The Top (over the open Internet)        |
+| PVR    | Personal Video Recorder                      |
+| TTP    | Trusted Third Party                          |
+| URI    | Usage Rights Information                     |
+| VM     | Virtual Machine                              |
+
+# 5 Conventions
+
+In this Recommendation:
+
+The keywords "**is required to**" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+
+The keywords "**is recommended**" indicate a requirement which is recommended but which is not absolutely required. Thus this requirement need not be present to claim conformance.
+
+The keywords "**is prohibited from**" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+
+The keywords "**can optionally**" indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's
+
+implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+In the body of this document and its annexes, the words *shall*, *shall not*, *should*, and *may* sometimes appear, in which case they are to be interpreted, respectively, as *is required to*, *is prohibited from*, *is recommended*, and *can optionally*. The appearance of such phrases or keywords in an appendix or in material explicitly marked as *informative* are to be interpreted as having no normative intent.
+
+# 6 Requirements for exchangeable embedded CA/DRM solutions
+
+## 6.1 General remarks
+
+The Group Specification on **ECI** basic requirements, as covered by the present Recommendation, is part of a multi-part deliverable specifying a system architecture for general purpose, software-based, embedded and exchangeable CA/DRM systems which would be the most appropriate and future-proof solution for overcoming market fragmentation and enabling interoperability. Key benefits of the envisaged approach for content security are:
+
+- Flexibility and scalability due to software-based implementation.
+- Exchangeability fostering future-proof solution and enabling innovation.
+- Applicability to content distributed via broadcast and broadband, including OTT.
+- Support of multi-screen environment.
+- Stimulation of the market for platform operators, network/service providers, and consumers by avoiding "Lock-in".
+- The specification of an open eco-system fostering market development.
+
+The **ECI** system aims at exchangeability of CA and DRM systems in CPEs on all relevant levels and aspects, at lowest possible costs for the consumers and at minimal restrictions for CA or DRM vendors to develop their target products for the PayTV market. Therefore, amongst others, the **ECI** has the following functionalities:
+
+- A software container for the CA respectively the DRM kernel – hereafter called **ECI Client** – with:
+  - standardized interfaces to all relevant functionalities of the CPE;
+  - a standardized **Virtual Machine (VM)** to run upon.
+- Support of smartcard-less systems as well as use in smartcard-based systems.
+- Inclusion of a multitude of such software containers in a CPE, each container running on its own instance of the **VM**.
+- Installation of the **ECI Client** independently from other CPE software by a secure and standardized loader concept.
+- **Advanced Security**, also known as Chip Set Security, to support content protection and to prevent unauthorized content access.
+- Methods for the user to discover the right **ECI Client** to download.
+- Methods for revocation of (parts of) the **ECI Client's** functionality and CPE's functionality.
+- Suited for classical digital broadcasting, IPTV or modern OTT-based systems.
+
+Although **ECI** shows some similarity with already deployed solutions, there are substantial differences:
+
+- 1) The module is in software, no longer in hardware, hence no need for costs at the consumer side to swap a CA or DRM system.
+
+- 2) Several parallel **ECI Clients** can be implemented in one and the same CPE, without adding relevant cost.
+- 3) These clients can run concurrently in one device.
+
+As a result, a CA or DRM component can be exchanged much easier, allowing the end-user to change operator or get services from a variety of operators on his CPE, without having to exchange expensive modules.
+
+The complete multi-part deliverable consists of a group of specifications, including a Group Specification on Use cases and requirements, in combination with the underlying specifications:
+
+- Part 1: Architecture, Definitions and Overview [ETSI GS ECI 001-1]
+- Part 2: Use cases and requirements [ETSI GS ECI 001-2]
+- Part 3: CA/DRM Container, Loader, Interfaces, Revocation [b-ETSI GS ECI 001-3]
+- Part 4: The Virtual Machine (VM) [b-ETSI GS ECI 001-4]
+- Part 5: The Advanced Security System [b-ETSI GS ECI 001-5]
+- Part 6: Trust Environment [b-ETSI GS ECI 001-6]
+- Part 7: Extended Requirements [b-ETSI GS ECI 001-7]
+
+which together describe a solution allowing replacement of **ECI Clients** at any time by just downloading the **ECI Clients** requested by an end customer. The **ECI Clients** are installed in a standard software container in the CPE by a separate loader, with separate security algorithms and keys to protect the **ECI Clients** against integrity and substitution attacks independently from all other software in the CPE. The container's interfaces with the CPE are generic and defined in GS ECI 001-3 [b-ETSI GS ECI 001-3], enabling the **ECI Client** to interact with the various functions in the CPE and beyond.
+
+The **ECI Clients** run upon a virtual machine instance that is defined in GS ECI 001-4 [b-ETSI GS ECI 001-4].
+
+GS ECI 001-5 [b-ETSI GS ECI 001-5] specifies an Advanced Security mechanism to protect the key to the content during its travel into the CPE processor chip's content decryption facility.
+
+This Recommendation addresses use cases and requirements as the basis for the implementation of interoperable CA/DRM systems in CPEs.
+
+The **ECI** specification only applies to the reception and further processing of content which is controlled by a Conditional Access and/or Digital Rights Management system and has been scrambled by the service provider. Content that is not controlled by a Conditional Access and/or DRM system is not covered by this Recommendation.
+
+The **ECI** Group Specification is intended to be used in combination with a contractual framework (license agreement), compliance and robustness rules, and appropriate certification process (see Note), under control of a **Trust Authority**, GS ECI 001-6 [b-ETSI GS ECI 001-6].
+
+The end-to-end security of an ECI compliant CA/DRM system is not subject to the technical specifications only. The ECI technology is only one element of an ECI compliant eco system, GS ECI 001-1 [ETSI GS ECI 001-1], which has to be created by a Trust Authority, also taking into account a legal framework, device certification and other issues. The following requirements are based on the use cases as given in Annex A:
+
+## 6.2 Generic requirements
+
+[R 01] **Embedded CI** shall be applicable to any broadcasting, broadband and hybrid (means a combination of broadcast and broadband) services, delivering Protected Content via any type of appropriate access network to any type of applicable device.
+
+- [R 02] **Embedded CI** shall define a **Software Container** for ECI kernel software and closely related CA/DRM software functionalities, clearly separated from the remaining software elements of a CPE.
+- [R 03] **Embedded CI** shall provide Enhanced Security features comparable to those available with today's state of the art CA/DRM Systems.
+- [R 04] **Embedded CI** shall allow the design of secure CA/DRM system implementations, which can be operated and maintained for a long period of time, in all cases for at least a 5 years period.
+
+## 6.3 Versatility related requirements
+
+- [R 05] **Embedded CI** shall support the implementation of more than one CA/DRM client in a CPE which provides a solution for the concurrent processing of at least two different **Protected Content** events.
+- [R 06] The architecture shall enable that different ECI clients in a CPE are able to recognize each other, can establish trust between each other, and are able to transfer content and the associated **URI** from one to another.
+- [R 07] The architecture shall enable that **ECI Clients** are able to establish trust to the **ECI Host** they are connected to and are able to securely transfer **URI** to the **ECI Host**.
+- [R 08] Compliance with national legal and regulatory requirements e.g., data privacy protection and protection of minors shall be ensured by **Embedded CI**.
+- [R 09] **Embedded CI** shall support the export of legally acquired **Protected Content** to other terminals (including mobile terminal devices) within a home domain or home network. This implies that the architecture provides the necessary interfaces that an ECI client in a CPE is able to talk to another ECI client in the same device. This shall only be possible in line with the usage rights issued by the respective content owners.
+- [R 10] An ECI client may be implemented in such a way, that it can export **Protected Content** to a non-ECI-compliant device. This shall only be possible in line with the usage rights issued by the respective content owners.
+
+## 6.4 Practicability related requirements
+
+- [R 11] **Embedded CI** shall provide APIs for the implementation of user interfaces providing excellent usability and easy handling of user interactions.
+- [R 12] **Embedded CI** should not add noticeable delay with respect to comparable CA/DRM solutions even if the affected two channels (services) use different CA/DRM systems. Note that it is not assumed that the CA/DRM system has to be swapped during a regular channel (service) change.
+- [R 13] All ECI related activities (e.g., normal operation, download of an **ECI Client**) should not have noticeable **impact** on the user experience and performance.
+
+## 6.5 ECI Client Swap related requirements
+
+- [R 14] **Embedded CI** shall allow changing to a new service provider without a required consent of the CA/DRM manufacturer, device manufacturer, platform, or service operator.
+- [R 15] In case of a swap of the ECI client the interruption of services shall be limited to a minimum.
+- [R 16] Subsequent to the exchange of an **ECI Client** the consumption of **Protected Content** (e.g., scrambled PVR content) legally acquired before the swap shall be possible without the need for any complex actions to be performed by the user.
+
+- [R 17] **Embedded CI** shall not unreasonably restrict the possibilities of CA/DRM vendors to develop different interoperable/swappable **ECI Clients** according to the market requirements.
+
+## 6.6 ECI System Security related requirements
+
+- [R 18] It shall be possible to securely download, to install and to exchange the **ECI Client** for a CPE, and it shall be possible to do so in a standardized way. Downloading and installing the **ECI client** shall rely solely on standardized solutions.
+- [R 19] The CPE shall provide a **Software Container**, which shall provide a unified abstraction layer to any ECI client. Note that the unified abstraction layer is what a virtual machine would provide to the ECI client.
+- [R 20] The **ECI Clients** and the **Host** system shall be able to assert and prove its trustworthiness at any time.
+- [R 21] **Embedded CI** shall support the development and establishment of a **Trust Authority**.
+- [R 22] **Embedded CI** shall not depend on a specific hardware (component) or a specific operating system being present. This requirement does not generally prohibit advanced security features, as long as the specification of those features are publicly available and those features are compliant with today's security architectures of relevant CPE chip vendors. Note that advanced security systems specified in a publicly available document are not considered as a specific hardware.
+- [R 23] The **Embedded CI** system shall allow the migration of existing DVB/ETSI compatible CA/DRM systems to this new **Embedded CI** System. Note that this implies that an operator can address with his existing CA/DRM system both the legacy devices as well as new ECI compliant devices running an ECI client compatible with the existing CA/DRM system.
+- [R 24] **Embedded CI** shall provide hooks allowing the backwards compatible further development of **Embedded CI** and ECI implementations. It shall be possible that existing ECI implementations are able to handle usage rights introduced by future feature extensions of the CPE capabilities or ECI client capabilities.
+- [R 25] **Embedded CI** shall support both system implementations with and without SmartCards as security devices and shall provide the resources for both types of solutions.
+- [R 26] **Embedded CI** shall provide the necessary functionalities for all levels of content security required for the different CA/DRM system applications. It shall be applicable to mass markets and to the full range of pay products, from low end to premium products.
+- [R 27] In case of an ECI client swap **Embedded CI** shall not require replacement of any hardware component. However, according to this requirement, the swap of a SmartCard of a SmartCard-based CA/DRM systems is generally not considered as a replacement of a hardware component.
+- [R 28] **Embedded CI** shall not require significantly more resources (processing power, memory, etc.) of the CPE device than comparable, available today, embedded CA/DRM systems and the implementation of the system architecture shall not imply significant higher/additional cost.
+- [R 29] **Embedded CI** shall support at least DVB CSA and advanced encryption standard (AES) scrambling systems and the Host shall support at least MPEG-Transport Stream (ISO/IEC 13818-1 [b-ITU-T H.222.0]) and ISOBMFF (ISO/IEC 14496-12 [b-ISO/IEC 14496-12:2012] including Amendment 3 and conforming to the signalling defined by the Common Encryption scheme as defined in ISO/IEC 23001-7 [b-ISO/IEC 23001-7:2011] file but potentially with a different encryption algorithm). Note that Support of this requirement would be compatible with DRMs used by digital entertainment content ecosystem (DECE)
+
+today and would provide a standard format for other DRMs to adopt for **Embedded CI** support.
+
+- [R 30] **Embedded CI** shall support a broad range of usage rights by providing the appropriate functionalities of the interface between the ECI container and the host.
+- [R 31] Embedded CI shall be able to describe usage rights and usage capabilities to an ECI client or from one ECI client to another.
+- [R 32] The Embedded CI shall provide a secure communication channel between ECI clients either on the same device or on different devices.
+
+# Annex A
+
+## Use Cases
+
+(This annex forms an integral part of this Recommendation.)
+
+The number of use cases covered in Annex A is not exhaustive.
+
+### A.1 Use case 1
+
+In the digital TV business environment, different reasons might occur that require exchanging the CA/DRM system in CPE equipment.
+
+- A digital media content provider may decide to change the CA/DRM system of CPEs for its customers. Reasons may be:
+  - Different technical or commercial reasons, such as requirements of enhanced CA/DRM functionalities, higher security levels or higher system performance or in case of a deep hack of the current system.
+  - Acquisition of new customers in a certain network, which used to access services of a competitor.
+- A platform operator may decide to change the CA/DRM system of CPEs in its platform. Reasons may be:
+  - Different technical or commercial reasons, such as requirements of enhanced CA/DRM functionalities, higher security levels or higher system performance or in case of a deep hack of the current system.
+  - Harmonization of technologies after acquisition of a network.
+- A CA/DRM vendor acquires a new customer which operates a platform, where a competitor had already established its CA system, or a CA/DRM vendor takes over another CA/DRM vendor and wants to harmonize the security technologies.
+- An end-user has bought a CPE in any shop and connects it to the network of access network provider A. One or more service providers offer their services over this network. The end-user can choose any of these services and download their CA/DRM system, if he is registered (including authentication and authorization) with the corresponding service provider. After some time, the same end-user decides to be connected to the network of access network provider B. He connects his CPE to this network. If his CPE supports the required reception technologies (e.g., DVB-C/C2, -S/S2, -T/T2, Ethernet, xDSL), one or more service providers offer their services over this network. The end-user can choose any of these services and exchange/swap the CA/DRM systems accordingly, if he is registered (including authentication and authorization) with the corresponding service provider.
+- A CE manufacturer wants to bring CPEs to the retail market, which support both FreeTV and PayTV. The CPEs may however be adapted for use with specific PayTV services by software upgrade with consent of the end-user.
+
+### A.2 Use case 2
+
+Today, if the CA-System of an installed base of CPEs of an operative CA platform has to be changed (for whatever reason), there are always four partners involved:
+
+- The current CA vendor.
+- The platform operator or digital media content provider.
+- The CPE manufacturer.
+- The new CA vendor.
+
+The current CA vendor has to provide the new vendor with both the technical information to access the installed base of CPEs, as well as a licence to use certain hardware components, protocols or software elements implemented in those CPEs. In any case the new CA-vendor has to adapt its CA System to the functionalities, hardware/software limitations and protocols available in the CPEs in the field. The CPE manufacturers have to integrate the new CA-System into the software of the different installed CPEs. In the worst case the swap of the CA/DRM system may be even not a viable technical/commercial option. This situation should be changed in order to achieve more interoperability.
+
+As proprietary security modules are today an integral part of most state of the art CA systems, CPEs are mostly manufactured for dedicated CA systems. This may limit the level of security that can be provided by a swapped CA system for CPEs in the field. This situation should be changed in a way that any security enhancement should be completely transferrable.
+
+### A.3 Use case 3
+
+The ECI system shall support consumption-only applications, including delivery of **Protected Content** to secondary devices. Two use cases are relevant for the support of secondary devices applications:
+
+- Centralized application: The gateway type, ECI compliant CPE is delivering usage rights information (URI) and encrypted content to the secondary device.
+- Decentralized application: The gateway type, ECI compliant CPE is delivering only URI to the secondary device and the secondary device derives the encrypted content from the network. Note that the ECI system has no requirements with respect to the implementation of a DRM client in a secondary device. In order to deliver protected content from a gateway to a secondary device it is only necessary that the two DRM clients are able to securely communicate between each other and the content owner support the implemented DRM system.
+
+### A.4 Use case 4 (Trusted third party (TTP) related use case)
+
+Today, any required unique IDs or certificates are embedded in CPE in a proprietary way, defined by the provider of the CA/DRM system. With respect to interoperability this is not an appropriate solution, as vendors will most likely not disclose the mechanisms to access their unique IDs or certificates. For example, the CI plus consortium has demonstrated that it is feasible to transfer the secure handling of certificates to a "Trusted Third Party". Similar solutions will be required for interoperable CA/DRM systems.
+
+# Bibliography
+
+- [b-ITU-T H.222.0] Recommendation ITU-T H.222.0 (2006) | ISO/IEC 13818-1 (2007), *Information technology – Generic coding of moving pictures and associated audio information: Systems.*
+- [b-ETSI GS ECI 001-3] ETSI GS ECI 001-3, *Embedded Common Interface (ECI) for exchangeable CA/DRM solutions; Part 3: The CA/DRM Container: Loader, Interfaces, Revocation.*
+- [b-ETSI GS ECI 001-4] ETSI GS ECI 001-4, *Embedded Common Interface (ECI) for exchangeable CA/DRM solutions; Part 4: The Virtual Machine.*
+- [b-ETSI GS ECI 001-5] ETSI GS ECI 001-5, *Embedded Common Interface (ECI) for exchangeable CA/DRM solutions; Part 5: The Advanced Security System.*
+- [b-ETSI GS ECI 001-6] ETSI GS ECI 001-6, *Embedded Common Interface (ECI) for exchangeable CA/DRM solutions; Part 6: Trust Environment.*
+- [b-ETSI GS ECI 001-7] ETSI GS ECI 001-7, *Embedded Common Interface (ECI) for exchangeable CA/DRM solutions; Part 7: Extended Requirements.*
+- [b-ETSI ISG ECI] ETSI ISG ECI White Paper-v1\_20 (2014), *Industry Specification Group on Embedded Common Interface for exchangeable CA/DRM solutions.*
+- [b-ISO/IEC 14496-12] ISO/IEC 14496-12:2012, *Information Technology – Coding of Audio-Visual Objects – Part 12: ISO Base Media file format.*
+- [b-ISO/IEC 23001-7] ISO/IEC 23001-7:2011, *Information technology – MPEG systems technologies – Part 7: Common encryption in ISO base media file format files.*
+
+
+
+## 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                                                                                                                       |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b>                                                        |
+| 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
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+
+
+**ITU-T**
+
+**J.1011**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+(09/2016)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Conditional access and protection – Exchangeable  
+embedded conditional access and digital rights  
+management solutions
+
+---
+
+**Embedded common interface for exchangeable  
+CA/DRM solutions; Architecture, definitions and  
+overview**
+
+Recommendation ITU-T J.1011
+
+
+
+# Recommendation ITU-T J.1011
+
+# Embedded common interface for exchangeable CA/DRM solutions; Architecture, definitions and overview
+
+## Summary
+
+Recommendation ITU-T J.1011 specifies an architecture for exchangeable, embedded conditional access/digital rights management or CA/DRM solutions, enabling consumer premises equipment (CPE), which are capable of receiving broadcast and broadband content, to download CA/DRM clients under a trusted environment. By utilizing a downloadable multi-CA/DRM service, entitled consumers can consume broadcast and broadband content, which is controlled by digital rights management (DRM) and/or CA systems, even though a CPE does not have a required content-related CA/DRM client available, by downloading it from a trusted source into various types of CPEs including set-top boxes (STBs), smart TVs, PCs, smart phones and/or smart tablets.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T J.1011   | 2016-09-02 | 9           | <a href="http://handle.itu.int/11.1002/1000/12773">11.1002/1000/12773</a> |
+
+## Keywords
+
+CA/DRM, exchangeable embedded common interface, retail CPE.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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 .....                                                | 1    |
+| 3.1 Terms defined elsewhere .....                                  | 1    |
+| 3.2 Terms defined in this Recommendation.....                      | 1    |
+| 4 Abbreviations and acronyms .....                                 | 2    |
+| 5 Conventions .....                                                | 3    |
+| 6 Architecture for exchangeable, embedded CA/DRM solutions .....   | 3    |
+| 6.1 General remarks.....                                           | 3    |
+| 6.2 The technical concept of the ECI system .....                  | 5    |
+| 7 Trust environment.....                                           | 11   |
+| 7.1 Necessary operational workflows.....                           | 12   |
+| Appendix I – Implementation of an ECI-compliant trust system ..... | 15   |
+| Bibliography.....                                                  | 17   |
+
+# Introduction
+
+Service and content protection realized by conditional access (CA) and digital rights management (DRM) are essential in the rapidly developing area of digital broadcast and broadband, including content, services, networks and customer premises equipment (CPE), to protect business models of content owners, network operators and PayTV operators. While conceptually CA focuses on mechanisms to access protected content distributed by a service provider over a network, DRM originally describes type and extent of the usage rights, according to the subscriber's contract.
+
+PayTV operators have established digital TV platforms, which implement standards for basic functions, extended with proprietary elements. Most CA and DRM systems used for classical digital broadcasting, Internet protocol television (IPTV) or new over-the-top (OTT) services capture consumer premises equipment (CPE) by binding it with proprietary security related elements. As a result, consumer premises equipment configured for use in network or platform A cannot be used in network or platform B or vice versa. Thus, the consumer electronics market for digital TV is still fragmented, as specifications differ not only per country, but also per platform. Detachable CA/DRM modules only offer a partial solution; the modules are again proprietary to the CA/DRM system, they are not cheap either and they are used primarily for cable or satellite TV and are not usable in modern-type equipment such as tablets due to lack of appropriate physical interfaces.
+
+Currently implemented solutions, whether embedded or as detachable hardware, result in "lock-in" effects. This seriously restricts the freedom of many players in digital multimedia content markets. Due to technological advances, innovative, software-based CA/DRM solutions become feasible. Maximizing interoperability while maintaining a high level of security, they promise to meet upcoming demands in the market, allow for new businesses, and broaden consumer choice.
+
+It is in consumers' interest that they are able to continue using the CPEs they bought e.g., after a move or a change of network provider or even utilize devices for services of different commercial video portals. This can only be achieved by interoperability of CPEs regarding CA and DRM, based on an appropriate security architecture. Further fragmentation of the market for CPEs can only be prevented and competition encouraged by ensuring a consumer-friendly and context-sensitive exchangeability of CA and DRM systems.
+
+# Recommendation ITU-T J.1011
+
+## Embedded common interface for exchangeable CA/DRM solutions; Architecture, definitions and overview
+
+# 1 Scope
+
+The object of this Recommendation is to specify functional entities of an architecture for an exchangeable, embedded common interface, in order to download any necessary CA/DRM system to CPE. The download process is operated under a trusted environment and enables the consumption of protected content delivered via broadcast and/or broadband connections with various types of terminal equipment in line with the acquired content rights of the end user. This Recommendation is one in a series of Recommendations, specifying the whole embedded common interface (ECI) eco-system.
+
+# 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.
+
+[ETSI GS ECI 001-1] ETSI GS ECI 001-1 (2014), *Embedded Common Interface for exchangeable CA/DRM solutions (ECI); Part 1: Architecture, Definitions and Overview*.
+
+[ETSI GS ECI 001-2] ETSI GS ECI 001-2 (2014), *Embedded Common Interface (ECI) for exchangeable CA/DRM solutions; Part 2: Use cases and requirements*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+None.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 advanced security:** Function of an ECI compliant CPE which provides enhanced security functions (hardware and software) for an ECI client. Note that the details are specified in [b-ETSI GS ECI 001-5].
+
+**3.2.2 ECI (embedded CI):** The architecture and the system specified in the ETSI ISG "embedded CI", which allows the development and implementation of software-based swappable ECI clients in customer premises equipment (CPE) and thus provides interoperability of CPE devices with respect to ECI.
+
+**3.2.3 ECI client (embedded CI client):** Implementation of a CA/DRM client which is compliant with the embedded CI specifications. Note that it is the software module in a CPE which provides all means to receive, in a protected manner and to control execution of a consumer's entitlements and rights concerning the content that is distributed by a content distributor or operator. It also
+
+receives the conditions under which a right or an entitlement can be used by the consumer and the keys to decrypt the various messages and content.
+
+**3.2.4 ECI client loader:** Software module part of the ECI host which allows downloading, verification and installation of new ECI client software in an ECI container of the ECI host.
+
+**3.2.5 ECI container (embedded CI container):** Abstract concept which provides an isolated environment comprised of a virtual machine and a single ECI client.
+
+**3.2.6 ECI host:** Hardware and software system of a CPE, which covers ECI related functionalities and has interfaces to an ECI client. Note that the ECI host is one part of the CPE firmware. The ECI host is responsible for ensuring the isolation of each ECI container and provides authenticated loading of ECI clients.
+
+**3.2.7 ECI host loader:** Software module which allows downloading, verification and installation of (new) ECI host software into a CPE. Note that in a multi-stage loading configuration this term is used to refer to all security critical loading functions involved in loading the ECI host.
+
+**3.2.8 trust authority (TA):** Organization governing all rules and regulations that apply to implementations of ECI. Note that the trust authority has to be a legal entity to be able to achieve legal claims. The trust authority needs to be impartial to all players in the downloadable CA/DRM ecosystem.
+
+**3.2.9 trusted third party (TTP):** Technical service provider which issues certificates and keys to compliant manufacturers of the relevant components of an ECI-system under control of the trust authority (TA).
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                   |
+|------|-----------------------------------|
+| API  | Application Programming Interface |
+| CA   | Conditional Access                |
+| CENC | Common Encryption                 |
+| CI   | Common Interface                  |
+| CPE  | Customer Premises Equipment       |
+| DRM  | Digital Rights Management         |
+| DVB  | Digital Video Broadcasting        |
+| ECI  | Embedded Common Interface         |
+| HD   | High Definition                   |
+| HTTP | Hypertext Transfer Protocol       |
+| iDTV | integrated Digital TV             |
+| IP   | Internet Protocol                 |
+| IPTV | Internet Protocol Television      |
+| LA   | License Agreement                 |
+| MPEG | Motion Picture Experts Group      |
+| OS   | Operating System                  |
+| OSD  | On Screen Display                 |
+| OTT  | Over-The-Top                      |
+
+|     |                                |
+|-----|--------------------------------|
+| PIN | Personal Identification Number |
+| PVR | Personal Video Recorder        |
+| ROM | Read Only Memory               |
+| SI  | Service Information            |
+| STB | Set-Top Box                    |
+| TA  | Trust Authority                |
+| TTP | Trusted Third Party            |
+| TV  | Television                     |
+| UI  | User Interface                 |
+| VM  | Virtual Machine                |
+
+# 5 Conventions
+
+In this Recommendation:
+
+The keywords "is required to" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed.
+
+The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely required. Thus this requirement need not be present to claim conformance.
+
+The keywords "is prohibited from" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed.
+
+The keywords "can optionally" indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+In the body of this Recommendation and its annexes, the words *shall*, *shall not*, *should*, and *may* sometimes appear, in which case they are to be interpreted, respectively, as *is required to*, *is prohibited from*, *is recommended*, and *can optionally*. The appearance of such phrases or keywords in an appendix or in material explicitly marked as *informative* are to be interpreted as having no normative intent.
+
+# 6 Architecture for exchangeable, embedded CA/DRM solutions
+
+## 6.1 General remarks
+
+ECI architecture, definitions and overview, as covered by this framework Recommendation, is part of a multi-part standard specifying a system architecture for general purpose, software-based, embedded and exchangeable CA/DRM systems which would be the most appropriate and future-proof solution for overcoming market fragmentation and enabling interoperability. Key benefits of the envisaged approach for content security are:
+
+- Flexibility and scalability due to software-based implementation
+- Exchangeability fostering future-proof solutions and enabling innovation
+- Applicability to content distributed via broadcast and broadband, including OTT
+- Support of multi-screen environment
+
+- Stimulation of the market for platform operators, network/service providers and consumers by avoiding "lock-in"
+- The specification of an open eco-system fostering market development.
+
+The ECI system aims at exchangeability of CA and DRM systems in CPEs on all relevant levels and aspects, at lowest possible costs for the consumers and at minimal restrictions for CA or DRM vendors to develop their target products for the PayTV market. The core element of ECI is to specify the interface between the software-based CA/DRM client and the host system. Therefore, amongst others, the ECI has the following functionalities:
+
+- A software container for the CA respectively the DRM kernel – hereafter called ECI client with:
+  - standardized interfaces to all relevant functionalities of the CPE
+  - a standardized virtual machine (VM) to run upon
+- Support of smartcard-less systems as well as use in smartcard-based systems
+- Inclusion of a multitude of such software containers in a CPE, each container running on its own instance of the VM
+- Installation of the ECI client independently from other CPE software by a secure and standardized loader concept
+- Advanced security, also known as chip set security, to support state-of-the-art content protection
+- Provisions to leverage hardware-assisted security functionalities
+- Methods for the user to discover the right ECI client to download
+- Methods for revocation of (parts of) the ECI client's functionality and CPE's functionality
+- Suited for classical digital broadcasting, IPTV or modern OTT-based systems.
+
+Although ECI shows some similarity with already deployed solutions, there are substantial differences:
+
+- (1) The CA/DRM client module is in software and no longer in hardware. Hence, no costs are incurred at the consumer side to swap a CA or DRM system.
+- (2) Several parallel ECI clients can be implemented in one and the same CPE, without adding relevant cost.
+- (3) These clients can run concurrently in the one device.
+
+As a result, a CA or DRM component can be exchanged much more easily, allowing the end user to change operators or get services from a variety of operators on his CPE, without having to exchange expensive modules.
+
+The complete multi-part standard consists of a group of specifications, including a framework specification, in combination with the underlying specifications:
+
+- Part 1: Architecture, definitions and overview [ETSI GS ECI 001-1]
+- Part 2: Use cases and requirements [ETSI GS ECI 001-2]
+- Part 3: CA/DRM container, loader, interfaces, revocation [b-ETSI GS ECI 001-3]
+- Part 4: The virtual machine (VM) [b-ETSI GS ECI 001-4]
+- Part 5: The advanced security system [b-ETSI GS ECI 001-5]
+- Part 6: Trust environment [b-ETSI GS ECI 001-6]
+- Part 7: Extended requirements [b-ETSI GS ECI 001-7]
+
+which together describe a solution allowing replacement of ECI clients at any time by just downloading the ECI clients requested by an end customer. The ECI clients are installed in a
+
+standard software container in the CPE by a separate loader, with separate security algorithms and keys to protect the ECI clients against integrity and substitution attacks independently from all other software in the CPE. The container's interfaces with the CPE are generic and defined in [b-ETSI GS ECI 001-3], enabling the ECI client to interact with the various functions in the CPE and beyond.
+
+The ECI clients run upon a virtual machine instance that is defined in [b-ETSI GS ECI 001-4].
+
+[b-ETSI GS ECI 001-5] specifies an advanced security mechanism to protect the key to the content during its travel into the CPE processor chip's content decryption facility.
+
+This Recommendation addresses an architecture and an overview of the relevant interface specifications for the implementation of interoperable CA/DRM systems in CPEs.
+
+The ECI specification only applies to the reception and further processing of content which is controlled by a conditional access and/or digital rights management system and has been scrambled by the service provider. Content that is not controlled by a conditional access and/or DRM system is not covered by this Recommendation.
+
+The ECI group specification is intended to be used in combination with a contractual framework (license agreement), compliance and robustness rules, and appropriate certification process (see note), under control of a trust authority [b-ETSI GS ECI 001-6]. Note that contractual framework (license agreement), compliance and robustness rules and appropriate certification processes are not subject to the standardization work in ISG ECI.
+
+## 6.2 The technical concept of the ECI system
+
+### 6.2.1 Basic considerations
+
+This Recommendation, in combination with Parts 2 to 5 and 7 of the specifications ([ETSI GS ECI 001-2], [b-ETSI GS ECI 001-3], [b-ETSI GS ECI 001-4], [b-ETSI GS ECI 001-5] and [b-ETSI GS ECI 001-7]), specifies an architecture allowing downloading, installation, upgrading, removal and replacement of ECI clients at any time, independently from other ECI clients running on the same host, the host CPE's system software or applications running on that host. An ECI host shall be capable to accommodate and to provide the runtime environment for at least two or as many ECI clients as its resources can handle. The ECI clients in a host have to run in parallel, enabling simultaneous decryption or re-encryption of different content streams from different operators.
+
+The technical concept described in this Recommendation and specified in [ETSI GS ECI 001-2], [b-ETSI GS ECI 001-3], [b-ETSI GS ECI 001-4] and [b-ETSI GS ECI 001-5], is applicable to both DVB multicrypt compliant CA systems and common encryption (CENC) compatible DRM systems.
+
+The CPE hosts a special loader only for ECI clients with the necessary security functionality to protect the integrity and authenticity of the ECI clients. This loader can be called and operated at any time to download and verify another ECI client at any time. The loader with its associated security facilities is specified in [b-ETSI GS ECI 001-3].
+
+Concerning this technical concept, each ECI client is installed in a separate software container, with an own virtual machine instance (VM instance), which is specified in [b-ETSI GS ECI 001-4]. The ECI container is specified for CA/DRM functionality only, which is reflected in [b-ETSI GS ECI 001-3]. The interface with the CPE, detailed in [b-ETSI GS ECI 001-3], enables the request and data exchange that is needed for the various CA/DRM functions. These requests and data exchanges may be performed between the ECI client and the host, between two ECI clients in the same host or two ECI clients in different hosts.
+
+TV-centric devices are defined as devices which include MPEG-2 transport stream processing inside the chip-set. ECI requires that those chip-sets implement ECI-compliant advanced security
+
+functionalities. [b-ETSI GS ECI 001-5] specifies provisions to leverage advanced security mechanisms in the chip-set, such as to protect the key associated with the content during its travel into the CPE processor chip's content decryption facility. This advanced security concept allows all ECI clients using the facility, if needed, to operate simultaneously and independently from each other.
+
+Devices for other environments, especially IPTV and tablets, smartphones, etc. typically implement more functionality in software and offer bidirectional IP-communication. This enables specific new types of security enhancement mechanisms. As chip-sets used in those devices include hardware for various processing security functions, ECI requires dedicated hardware-assisted security and robustness functionalities to be implemented in order to achieve ECI-compliance. Therefore, the specification [b-ETSI GS ECI 001-3] includes methods for the ECI client to obtain the relevant parameters of the host's technical capabilities and functionalities, as far as relevant, including possible support of the advanced security as specified in [b-ETSI GS ECI 001-5].
+
+The advanced security functionalities are available simultaneously to any ECI client active in a CPE. ECI clients can also be deployed in platforms with DVB compliant CA systems or with CENC compliant DRM systems running in simulcrypt or multicrypt mode, as long as the server sides of those systems are compliant with the respective DVB/CENC backend standards.
+
+### **6.2.2 Architectural overview**
+
+The ECI allows CA/DRM providers to implement solutions for conditional access (CA) as well as for digital rights management (DRM) within the domain of an individual customer. Figure 1 shows a reference configuration which is fully supported by a complete ECI implementation.
+
+In order to support multi-screen environments within the individual consumer's domain, ECI clients within that domain may communicate with each other, and may make use of a bidirectional network with the provider, depending on the availability of appropriate networks and supporting functionalities in the CA/DRM systems and their ECI clients. [b-ETSI GS ECI 001-3] gives further details.
+
+An ECI client may be implemented in such a way that it is able to operate as a gateway also to non-ECI-conformant clients. The necessary hooks therefore are specified in [b-ETSI GS ECI 001-5]. The specific protocols and implementations of proprietary clients are out of scope of the ECI specifications.
+
+![Figure 1: Diagram showing ECI clients within a single customer's domain. A Content Distributor on the left is connected via Public networks to a Subscriber's domain on the right. Inside the domain, there is a Primary CPE containing ECI client 1 (gateway), ECI client 2, and ECI client 3 (gateway). ECI client 1 is connected to ECI client 2 and ECI client 3. ECI client 3 is connected to a Secondary CPE containing Proprietary CA/DRM. ECI client 4 (Secondary CPE) is also connected to the Proprietary CA/DRM.](af7916c89a458fdab6c3f443217388ae_img.jpg)
+
+J.1011(16)\_F01
+
+Figure 1: Diagram showing ECI clients within a single customer's domain. A Content Distributor on the left is connected via Public networks to a Subscriber's domain on the right. Inside the domain, there is a Primary CPE containing ECI client 1 (gateway), ECI client 2, and ECI client 3 (gateway). ECI client 1 is connected to ECI client 2 and ECI client 3. ECI client 3 is connected to a Secondary CPE containing Proprietary CA/DRM. ECI client 4 (Secondary CPE) is also connected to the Proprietary CA/DRM.
+
+**Figure 1 – The ECI clients within a single customer's domain**
+
+The ECI specifications define, amongst others, the interface between an ECI container and the ECI host. Figure 2 shows a block diagram of a CPE with ECI containers and the other functions in the ECI host that the ECI containers communicate with or may communicate with. Some of these functions are optional. During the installation of an ECI client and during launch of an ECI client, the host specifies which relevant functions it has available to the ECI client.
+
+![Figure 2: Block diagram of a CPE with embedded ECI clients. The CPE contains a Smart-card (optional), Applications, middleware, system software, and a Browser. It also contains two ECI containers, each with an ECI client and a Virtual machine instance. The ECI host is shown below the containers, containing OS/Drivers, ECI-Advanced security, and Loaders. The entire system is built on top of the Hardware layer.](ff0952ef692c9d960ce5f6708bcc9711_img.jpg)
+
+J.1011(16)\_F02
+
+Figure 2: Block diagram of a CPE with embedded ECI clients. The CPE contains a Smart-card (optional), Applications, middleware, system software, and a Browser. It also contains two ECI containers, each with an ECI client and a Virtual machine instance. The ECI host is shown below the containers, containing OS/Drivers, ECI-Advanced security, and Loaders. The entire system is built on top of the Hardware layer.
+
+**Figure 2 – Block diagram of a CPE with embedded ECI clients, each with their own ECI container and virtual machine instance**
+
+First of all the concept is based on a hierarchical loader concept (see Figure 3) consisting of a chip-based loader, the system software loader and the ECI client loader.
+
+The ECI host loader loads the ECI host software. This includes besides other elements the virtual machine, access to advanced security components and the ECI client loader. An ECI host can load multiple ECI clients into separate virtual machine instances, which run independently and are isolated from each other.
+
+When loading an ECI client into the system a virtual machine instance is being created in which the ECI client is loaded. This VM instance acts as a sandbox between the ECI client and the host. The interface between the ECI client and the VM instance is the key interface which the Group Specification (GS) is specifying. The interface specifies in addition the information flow/protocol between multiple instances of such an ECI client and to other functionality inside the CPE, like advanced security, display, etc. Note that the other ECI client needs not necessarily to be in the same ECI host. This interface and communication protocol is specified in [b-ETSI GS ECI 001-3].
+
+The ECI host itself depends on the manufacturer implementation. It interfaces to the OS and the driver layer and provides all functionalities defined by the ECI client interface specification. The ECI-host is not specified by ECI, but it needs to be certified by the TA in order to ensure compliance with the ECI client interface specification.
+
+### 6.2.3 Mandatory functionality of ECI compliant devices
+
+ECI addresses a range of usage scenarios (see Figure 1). Hence, ECI has to deal with a broad range of devices such as iDTVs, STBs, personal video recorders (PVRs), IPTV, tablets, smartphones, etc. These devices vary in their capabilities while ECI provides a harmonized security framework. ECI distinguishes TV-centric devices from devices for other environments, including but not limited to IPTV and tablets.
+
+TV-centric devices are defined as devices which include MPEG-2 transport stream processing inside the chip-set. ECI requires that those chip-sets implement ECI-compliant advanced security functionalities. TV-centric ECI compliant CPEs shall be compliant with the functions as given in the specifications [b-ETSI GS ECI 001-3], [b-ETSI GS ECI 001-4] and [b-ETSI GS ECI 001-5].
+
+Devices for other environments especially IPTV, computers and tablets typically implement more functionality in software and connect to a bidirectional IP-communication. This enables different types of security mechanisms. As chip-sets used in these devices include hardware for various security processing functions, ECI requires dedicated hardware-assisted security and robustness functionalities to be implemented in the chip-sets. [b-ETSI GS ECI 001-3], [b-ETSI GS ECI 001-4] and [b-ETSI GS ECI 001-5] specify the necessary mechanisms to leverage those functionalities.
+
+### 6.2.4 Necessary interfaces between ECI host and ECI client
+
+The ECI container is a technical concept combining the VM and the ECI client with the objective to isolate and to shield the VM and the ECI client from the rest of the CPE. The virtual machine is a functionality of the ECI host. By loading an ECI client the ECI host creates a virtual machine instance. The virtual machine provides the necessary interfaces to the ECI client and connects them to the ECI host. The ECI specification defines the interface between the VM and the ECI client, see also Figure 2 for a high level architecture on an ECI compliant device. The interface provides certain application programming interfaces (APIs) and also establishes a secure communication channel.
+
+The following list highlights important software interfaces:
+
+- Interface for capability information to ECI client from ECI host and vice versa
+- Interface to the processing of input and outputs signals of the CPE
+- Interface to the advanced security hardware/drivers block
+- Interface to loader functionalities
+- Interface to support user interaction
+
+- Interface to encryption and decryption functionality
+- Interface to the optional smartcard reader
+- Interface to specific security functionalities like fingerprinting and watermarking
+- Interface to local storage
+
+All interfaces of the ECI client are provided by means of the virtual machine.
+
+There are in addition communication protocols on top of the interfaces allowing a secure communication. In particular a protocol to established communication between ECI clients, regardless if internal or external, is being specified.
+
+The CPE can be connected to any type of network and several networks concurrently, both unidirectional or bidirectional. It does not always need to be connected to any network (downloaded/stored content).
+
+### **6.2.5 A minimum user interface and display functionality**
+
+For communications with the user, a minimum user interface (UI) and on screen display (OSD) facility shall be available to the ECI containers. This is specified in [b-ETSI GS ECI 001-3]. It is used to display messages for the user that have been generated by or sent using the CA/DRM system. Also, it is used to allow the user entering inputs, such as a personal identification number (PIN). Details are specified in [b-ETSI GS ECI 001-3] as well.
+
+The user interacts locally with the CA/DRM system through the ECI client.
+
+### **6.2.6 The virtual machine**
+
+The ECI client runs upon a standardized virtual machine (VM). This component is specified in [b-ETSI GS ECI 001-4]. Each installed ECI client shall have its own instance of the VM. The VM instance provides a secured environment for executing conditional access kernel or digital rights management client applications. APIs are provided by the VM, where resources of the ECI host environment can be accessed in a standardized way.
+
+### **6.2.7 The advanced security facility**
+
+ECI defines minimum necessary security functionalities required to build a secure content protection system. ECI requires enhancements based on hardware-elements. In TV-centric devices this is delivered by TV-specific dedicated advanced security functions. It specifies what is usually referred to as a "key ladder block" in systems on chip (SoCs). An essential task of the advanced security facility is to protect the content protection keys during its transmission from the ECI client to the content decryption facility in a CPE or the transfer of protected content from one ECI client to another ECI client (see Figure 1). The advanced security system as specified in [b-ETSI GS ECI 001-5] supports different simultaneous control word streams and different ECI clients that are simultaneously requesting its services. Furthermore the advanced security facility plays a key role to verify the download of the software for the host and the ECI clients.
+
+Devices for other environments especially IPTV, computers and tablets typically implement more functionality in software and connect to a bidirectional IP-communication. ECI specifies the same advanced security concepts and mechanisms but will map them differently on the devices security architectures [b-ETSI GS ECI 001-3], [b-ETSI GS ECI 001-4] and [b-ETSI GS ECI 001-5].
+
+The availability of advanced security in the CPE is communicated to the ECI client during its installation and during its launch.
+
+### **6.2.8 Re-scrambling**
+
+Protected content, which is been received by an ECI compliant CPE may not be consumed immediately. The following functionalities are available with ECI compliant devices:
+
+- Local storage:
+  - under control of the CPE
+  - under control of a CA- or DRM client
+- Gateway:
+  - delivery of a protected content element to an external device under control of a DRM client
+  - delivery of a protected content element to another ECI client either inside the same CPE or running on another ECI compliant CPE.
+
+To support these functionalities the ECI compliant device is able to re-scramble content. The ECI system does not specify the transport mechanisms nor the available DRM functionalities for storage or delivery of protected content to other devices. In [b-ETSI GS ECI 001-5], the necessary interfaces between the ECI host and the ECI client are defined.
+
+### 6.2.9 The ECI loader functionalities
+
+An ECI compliant CPE shall provide loader functionalities, allowing loading and installation, as well as integrity and anti-substitution protection of the relevant software modules of the ECI system.
+
+Initially, the loader integrated into the chip loads the system software loader. This embedded loader is to ensure that only a certified system software loader can be installed and launched. The system software loader includes the ECI host loader and thus the system software loader needs to be signed by the trust authority. The system software loader may include loaders for other system software which is not relevant for ECI functionalities and has no relationship to the security related elements of the system. The ECI host software includes the ECI client loader, which then upon request can load the ECI client.
+
+During its installation in its ECI container as well as during its launch, the ECI client is informed by the ECI host about its facilities, such as recording facilities, HD facilities, a smart card reader, fingerprinting and watermarking facilities and networks, as well as compliance with the framework specification (this Recommendation) and [b-ETSI GS ECI 001-3], [b-ETSI GS ECI 001-4] and [b-ETSI GS ECI 001-5] and possibly [b-ETSI GS ECI 001-6].
+
+The ECI loader with the related security facilities is specified in [b-ETSI GS ECI 001-3].
+
+![Figure 3 – Hierarchical loader concept. The diagram illustrates a four-level hierarchy of loaders. At the top is a 'Chip' containing an 'Embedded loader' and a 'Certificate (public key) from TA'. A red arrow points down to the 'System software loader', which contains a 'Loader of additional elements' and an 'ECI host loader', and is associated with a 'Signature from TA'. From the 'System software loader', a green arrow points to 'Other system software' and a red arrow points down to the 'ECI-host'. The 'ECI-host' contains a list of components: VM, File system, Libraries for security, Protection system controls, ECI client loader, and '.....', and is associated with a 'Signature from TA'. A red arrow points down from the 'ECI-host' to the 'ECI-client', which is also associated with a 'Signature from TA'. The text 'J.1011(16)_F03' is located at the bottom right of the diagram.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg)
+
+Figure 3 – Hierarchical loader concept. The diagram illustrates a four-level hierarchy of loaders. At the top is a 'Chip' containing an 'Embedded loader' and a 'Certificate (public key) from TA'. A red arrow points down to the 'System software loader', which contains a 'Loader of additional elements' and an 'ECI host loader', and is associated with a 'Signature from TA'. From the 'System software loader', a green arrow points to 'Other system software' and a red arrow points down to the 'ECI-host'. The 'ECI-host' contains a list of components: VM, File system, Libraries for security, Protection system controls, ECI client loader, and '.....', and is associated with a 'Signature from TA'. A red arrow points down from the 'ECI-host' to the 'ECI-client', which is also associated with a 'Signature from TA'. The text 'J.1011(16)\_F03' is located at the bottom right of the diagram.
+
+**Figure 3 – Hierarchical loader concept**
+
+### 6.2.10 Revocation
+
+The trust authority may decide to put a CPE, a range of CPEs, a type of CPEs or all CPEs from a specific manufacturer on a black list. The content provider or operator may revoke these concerned CPE or CPEs from their service distribution point. The methods used allow other operators and content distributors to continue their services to these CPEs if they wish to do so.
+
+Revocation can block all services from the operator or content provider to the CPE(s) concerned, or to a subset of services. This is subject to the functionality of the relevant CA or DRM system and out of the scope of the present Recommendation.
+
+The revocation process is specified in [b-ETSI GS ECI 001-3].
+
+# 7 Trust environment
+
+In order to be able to establish a system based on embedded CI, a trust environment has to be set up. Details about the trust environment are out of scope of the ECI specifications. However, the principles, which are specified in [b-ETSI GS ECI 001-6], are essential in order to fully understand how ECI works.
+
+The trust authority (TA) is an organization governing all rules and regulations that apply to implementations of the ECI architecture. The trust authority has to be a legal entity to be able to
+
+achieve legal claims. The trust authority needs to be impartial to all players in the downloadable CA/DRM ecosystem. This includes:
+
+- CPE manufacturers
+- CA/DRM (ECI client) manufacturers
+- Chipset manufacturers, whose components include unchangeable secure processor keys and certificates, which are necessary for interaction between host and the compliant CA/DRM system
+- Platform operators; the platform operator is the party that controls all necessary elements of a CA/DRM system. Platform operators are for example service providers or network operators
+- Application providers, if applicable
+
+A trusted third party (TTP) is a technical service provider, which issues certificates and keys to compliant manufacturers of the relevant components of an ECI system. The trust of these keys and certificates is assured by the TA, which holds the root of trust.
+
+Trust authority and trusted third party form the basis for the chain of trust and thus have to be involved in the entire processes ranging from production (chips and CPEs), over operations (secure ECI client download and activation) to control measures (e.g., revocation).
+
+The trust authority as a legal entity ensures the functioning of the trust environment via a contractual framework also called license agreement, under which the various parties involved can assume their responsibilities and liabilities. Under the license agreement trust authority/trusted third party are generating and issuing key pairs, certificates, test credentials and operator IDs, etc.
+
+One TA establishes trust between all market participants. A second TA cannot exist to establish trust "a second time" for the same environment. However, there could be multiple TAs, e.g., per country or per region, segments, eco-systems.
+
+If multiple TAs exist in parallel there is a need that TA A and TA B trust each other as a prerequisite that devices registered in TA A can be used in the domain of TA B.
+
+## **7.1 Necessary operational workflows**
+
+This clause gives a first overview of the necessary operational workflows, which serve the needs of the different market participants in order to implement a business based on the ECI technology. Furthermore the indicated workflows are based on the essential technical elements which are necessary for implementation of an ECI system. Figure 4 shows these interactions between technical components and the relevant market participants.
+
+Remark: The description is generic and is not intended to reflect any existing proprietary solution or any actual running standardization activity.
+
+![Figure 4 – Necessary trust management between trust authority (TA) and the relevant market participants](b2d16e07bfa79d67a8adabf7e26c7764_img.jpg)
+
+```
+
+graph TD
+    CPEM1[CPE manufacturer] --> ECI_CL[ECI-Client loader]
+    ECI_CL <--> TA[Trust authority]
+    ECI_H[ECI host] --- ECI_CL
+    ECI_CM[ECI-Client manufacturer] --> ECI_CF[ECI-Client firmware]
+    ECI_CF <--> TA
+    AN[Access network] --> PO[Platform operator]
+    PO <--> TA
+    TA <--> CL[Chip loader]
+    TA <--> FL[Firmware loader]
+    CL --- CPEC[CPE chipset]
+    FL --- CPEHF[CPE Hard-/Firmware]
+    CSM[Chipset manufacturer] --> CPEC
+    CPEM2[CPE manufacturer] --> CPEHF
+
+    style TA fill:#add8e6
+    style ECI_CL fill:#ffff00
+    style CL fill:#ffff00
+    style FL fill:#ffff00
+    style CPEM1 fill:#ffc0cb
+    style ECI_CM fill:#ffc0cb
+    style PO fill:#ffc0cb
+    style CSM fill:#ffc0cb
+    style CPEM2 fill:#ffc0cb
+    linkStyle 1,4,7,8,9 stroke:red,stroke-width:2px;
+  
+```
+
+**Figure 4 – Necessary trust management between trust authority (TA) and  
+the relevant market participants**
+
+Figure 4 – Necessary trust management between trust authority (TA) and the relevant market participants
+
+The operational and related contractual issues (see red arrows in Figure 4) for the trust environment are:
+
+- Integrity  
+ Integrity means the requirement that one market participant is able to verify whether a hardware/software component provided by another market participant has not been modified by any unauthorized party and is fulfilling the specifications and robustness rules. This requirement can be fulfilled by suitable credentials and signatures and testing procedures based on test credentials provided by the trust authority/trusted third party.
+
+- Authenticity  
+ Authenticity means that any hardware/software component which originates from a TA contract partner of the trust authority and which has passed the necessary verification and certification steps can clearly be associated with the contract partner and thereby distinguished from any cloned component. Authenticity of any relevant hardware/software component is proven by any ECI system.
+
+- Contractual Framework  
+ The contractual framework established by the trust authority as a legal entity shall encompass a compliance and robustness regime and certification procedures in order to provide the environment for the establishment of ECI systems.
+
+- Remedies  
+ In the case where hardware/software components of an ECI system are no longer compliant, the trust authority establishes procedures for the provider of that component, targeting to re-establish the integrity of the eco-system in a reasonable timeframe.
+
+**Rec. ITU-T J.1011 (09/2016)**      13
+
+Essential technical components (yellow boxes in Figure 4) are:
+
+### 1) CPE chipset
+
+The CPE chipset is the main component within CPE hardware which usually includes "system on chip" (SoC) due to existing requirements of platform operators and content providers. Furthermore usually the chip loader is included in the CPE chip.
+
+### 2) CPE hardware
+
+The secure CPE chipset implementation, prevention of any unauthorized access to storage elements (Flash, ROM) and protection of interfaces are essential issues.
+
+### 3) Different loaders
+
+The chip loader downloads different additional loaders, depending on the hardware/software configuration of the CPE.
+
+### 4) CPE firmware
+
+The CPE firmware has manifold interactions with the ECI client and all relevant CPE hardware interfaces. Security is ensured by detailed specifications and appropriate compliance and robustness rules.
+
+### 5) ECI client
+
+The ECI client extracts all CA and DRM related information delivered by the frontends of the CPE and initiates the corresponding settings within the CPE device (descrambler, interfaces), which obviously needs close and secure interaction with the CPE firmware.
+
+## Appendix I
+
+### Implementation of an ECI-compliant trust system
+
+(This appendix does not form an integral part of this Recommendation.)
+
+Appendix I gives a first overview of the necessary operational workflows, which serve the needs of the different market participants in order to implement a business based on the ECI technology. Figure I.1 shows an overview of the general workflow. Furthermore the indicated workflows are based on the essential technical elements which are necessary for implementation of an ECI system. Figure 4 in clause 7.1 shows the interactions between technical components and the relevant market participants.
+
+![Figure I.1 – General workflow overview. A flowchart showing the interactions between a Trust authority (TA), a Trusted third party (TTP), a Chipset manufacturer, a CPE manufacturer, a Platform operator, a CA/DRM provider, and a Test centre. The TA points to the TTP. The TTP has bidirectional arrows with each of the other five entities, labeled 'Credentials, keys legal arrangement'. The Chipset manufacturer, CPE manufacturer, Platform operator, and CA/DRM provider are connected vertically by downward arrows. The Chipset manufacturer and CPE manufacturer have bidirectional arrows with the Test centre labeled 'Device testing testing results'. The Platform operator and CA/DRM provider also have bidirectional arrows with the Test centre labeled 'Device testing testing results'. A dashed arrow points from the CPE manufacturer to the Platform operator, labeled 'Applicable only to OEM markets'. The diagram is labeled J.1011(16)_FI.1 at the bottom right.](a3472689858b068ef469213682965325_img.jpg)
+
+```
+graph LR
+    TA[Trust authority (TA)] --> TTP[Trusted third party (TTP)]
+    TTP <--> CM[Chipset manufacturer]
+    CM --> CPM[CPE manufacturer]
+    CPM --> PO[Platform operator]
+    PO --> CDRMP[CA/DRM provider]
+    TTP <--> CPM
+    TTP <--> PO
+    TTP <--> CDRMP
+    CM <--> TC[Test centre]
+    CPM <--> TC
+    PO <--> TC
+    CDRMP <--> TC
+    CPM -.-> PO : Applicable only to OEM markets
+```
+
+Figure I.1 – General workflow overview. A flowchart showing the interactions between a Trust authority (TA), a Trusted third party (TTP), a Chipset manufacturer, a CPE manufacturer, a Platform operator, a CA/DRM provider, and a Test centre. The TA points to the TTP. The TTP has bidirectional arrows with each of the other five entities, labeled 'Credentials, keys legal arrangement'. The Chipset manufacturer, CPE manufacturer, Platform operator, and CA/DRM provider are connected vertically by downward arrows. The Chipset manufacturer and CPE manufacturer have bidirectional arrows with the Test centre labeled 'Device testing testing results'. The Platform operator and CA/DRM provider also have bidirectional arrows with the Test centre labeled 'Device testing testing results'. A dashed arrow points from the CPE manufacturer to the Platform operator, labeled 'Applicable only to OEM markets'. The diagram is labeled J.1011(16)\_FI.1 at the bottom right.
+
+NOTE – Trusted third party (TTP) and test centre are contract partners of the trust authority (TA) for certification and key issuing process.
+
+**Figure I.1 – General workflow overview**
+
+### Legal/Contractual framework
+
+Secure trust management can only be carried out under a clearly defined legal and contractual framework, in which the license agreement (LA) constitutes the core element. The TA provides license agreements to anyone seeking to implement the specification(s), be they CPE manufacturers, CA/DRM system vendors, chip manufacturers, other technology providers, platform operators, etc.
+
+Therefore the license agreement is the essential instrument for the TA to create, maintain and make available to the horizontal market a secure but user friendly method to receive and make operative all required keys and other relevant security related material and information when connecting CPEs to providers of choice, that conform to the relevant usage rules. Similarly, the license agreement framework enables the TA to take proper care of revocation of all security material when a consumer is disconnected by the provider, as far as is technically and economically possible.
+
+The license agreement enables the coordinated and consistent application of the other elements of the contractual framework such as the technical specification, compliance and robustness rules, obligations and liabilities, testing and certification, implementation guidelines, etc.
+
+Figure I.2 shows components of the license agreement.
+
+![Flowchart showing the components of a license agreement. The top level is 'License, agreement'. It branches into three main components: 'Specification of technical elements 1)', 'Compliance and robustness rules', and 'Rights, obligations, liability of manufacturers'. Below 'Specification of technical elements 1)' are 'Implementation guidelines' and 'Certification of products'. Below 'Compliance and robustness rules' is 'Rights, obligations, liability of platform operators'. The text 'J.1011(16)_Fl.2' is in the bottom right corner.](e69b9188aa2c14ec6b21c83f711fef65_img.jpg)
+
+```
+
+graph TD
+    LA[License, agreement] --> S[Specification of technical elements 1)]
+    LA --> C[Compliance and robustness rules]
+    LA --> R1[Rights, obligations, liability of manufacturers]
+    S --> IG[Implementation guidelines]
+    S --> CP[Certification of products]
+    C --> R2[Rights, obligations, liability of platform operators]
+    J101116Fl2[J.1011(16)_Fl.2]
+  
+```
+
+Flowchart showing the components of a license agreement. The top level is 'License, agreement'. It branches into three main components: 'Specification of technical elements 1)', 'Compliance and robustness rules', and 'Rights, obligations, liability of manufacturers'. Below 'Specification of technical elements 1)' are 'Implementation guidelines' and 'Certification of products'. Below 'Compliance and robustness rules' is 'Rights, obligations, liability of platform operators'. The text 'J.1011(16)\_Fl.2' is in the bottom right corner.
+
+**Figure I.2 – Components of the license agreement**
+
+These specifications will be developed in the ETSI ISG ECI as Group Specifications.
+
+# Bibliography
+
+- [b-ITU-T H.222.0] Recommendation ITU-T H.222.0 (2006) | ISO/IEC 13818-1:2007, *Information technology – Generic coding of moving pictures and associated audio information: Systems*.
+- [b-CENELEC EN 50221] CENELEC EN 50221 (1997), *Common Interface Specification for Conditional Access and other Digital Video Broadcasting Decoder Applications*.
+- [b-CI Plus Specification] CI Plus Specification (V1.3.1) (2011), *Content Security Extensions to the Common Interface*.
+- [b-ETSI EN 300 468] ETSI EN 300 468 V1.13.1 (2012), *Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB systems*.
+- [b-ETSI ISG ECI] ETSI ISG ECI White Paper (2014), *Industry Specification Group on Embedded Common Interface for exchangeable CA/DRM solutions*.  
+[www.etsi.org/deliver/etsi.../ECI/.../gs\\_ECI00101v010101p.pdf](http://www.etsi.org/deliver/etsi.../ECI/.../gs_ECI00101v010101p.pdf)
+- [b-ETSI TS 101 699] ETSI TS 101 699 V1.1.1 (1999), *Digital Video Broadcasting (DVB); Extensions to the Common Interface Specification*.  
+<http://webstore.ansi.org/RecordDetail.aspx?sku=ETSI+TS+101+699-v1.1.1-1999-11>
+- [b-ETSI TS 103 162] ETSI TS 103 162 V1.1.1 (2010), *Access, Terminals, Transmission and Multiplexing (ATTM); Integrated Broadband Cable and Television Networks; K-LAD Functional Specification*.
+- [b-ETSI TS 103 205] ETSI TS 103 205 V1.1.1 (2014), *Digital Video Broadcasting (DVB); Extensions to the CI Plus™ Specification*.
+
+
+
+
+
+## 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                                                                                                                       |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b>                                                        |
+| 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
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+
+
+![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**
+
+**J.11**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**TELEVISION AND SOUND TRANSMISSION**
+
+---
+
+**HYPOTHETICAL REFERENCE CIRCUITS FOR  
+SOUND-PROGRAMME TRANSMISSIONS**
+
+**ITU-T Recommendation J.11**
+
+(Extract from the *Blue Book*)
+
+---
+
+# NOTES
+
+1 ITU-T Recommendation J.11 was published in Fascicle III.6 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 J.11
+
+# HYPOTHETICAL REFERENCE CIRCUITS FOR SOUND-PROGRAMME TRANSMISSIONS<sup>1), 2), 3)</sup>
+
+(Geneva, 1972; amended at Geneva, 1976, and at Melbourne, 1988)
+
+## Terrestrial systems and systems in the fixed-satellite service
+
+The CCITT,
+
+considering
+
+- (a) that there is a need to define a hypothetical reference circuit to enable design performance standards to be set;
+- (b) that the hypothetical reference circuit should allow the different types of sound-programme circuits to be compared on a common basis,
+
+unanimously recommends
+
+- (1) that the main features of the hypothetical reference circuit for sound-programme transmissions over a terrestrial system (shown in a Figure 1/J.11), which may be provided by either radio or cable, should be:
+  - the overall length between audio points (B and C) is 2500 km,
+  - two intermediate audio points (M and M') which divide the circuit into three sections of equal lengths,
+  - the three sections which are lined up individually and then inter-connected without any form of overall adjustment or correction;
+- (2) that the main features of the hypothetical reference circuit for sound-programme transmissions over a system in the fixed-satellite service (shown in Figure 2/J.11) should be:
+  - one link: earth station – satellite – earth station,
+  - one pair of modulation and demodulation equipments for translation from baseband to radio frequency, and from radio frequency to baseband, respectively.
+
+![Diagram of a hypothetical reference circuit for sound-programme transmissions over a terrestrial system. It shows a horizontal line representing the circuit, with four points marked by dots: B, M, M', and C. A dimension line below the line indicates the total length between B and C is 2500 km. The text 'CCITT - 15570' is written below the dimension line.](f89631cc38aa971e8d15cbffe28f1183_img.jpg)
+
+The diagram illustrates a horizontal line representing a terrestrial sound-programme transmission circuit. Four points are marked on the line with solid black dots, labeled from left to right as B, M, M', and C. A dimension line with vertical end-caps spans the distance between points B and C, with the text "2500 km" centered below it. To the right of the dimension line, the text "CCITT - 15570" is printed.
+
+Diagram of a hypothetical reference circuit for sound-programme transmissions over a terrestrial system. It shows a horizontal line representing the circuit, with four points marked by dots: B, M, M', and C. A dimension line below the line indicates the total length between B and C is 2500 km. The text 'CCITT - 15570' is written below the dimension line.
+
+FIGURE 1/J.11
+
+**Hypothetical reference circuit for sound-programme transmissions over a terrestrial system**
+
+- 1) This Recommendation corresponds to CCIR Recommendation 502.
+- 2) The hypothetical reference circuits defined in this Recommendation should apply for both analogue and digital systems.
+- 3) For maintenance purposes there may be a need to define other circuits of which an illustration is shown in Annex A of this Recommendation.
+
+![Diagram of a hypothetical reference circuit for sound-programme transmissions over a system in the Fixed-Satellite Service. The diagram shows two earth stations (labeled 1) connected to a space station (labeled 2) via dashed lines. A horizontal line (labeled 3) connects the two earth stations, representing the hypothetical reference circuit. The text 'CCITT-15581' is visible near the right earth station. A legend below the diagram defines: 1: Earth station, 2: Space station, 3: Hypothetical reference circuit.](2763901b7a1fd1b5d704cdc450d12ed0_img.jpg)
+
+1 : Earth station  
+2 : Space station  
+3 : Hypothetical reference circuit
+
+Diagram of a hypothetical reference circuit for sound-programme transmissions over a system in the Fixed-Satellite Service. The diagram shows two earth stations (labeled 1) connected to a space station (labeled 2) via dashed lines. A horizontal line (labeled 3) connects the two earth stations, representing the hypothetical reference circuit. The text 'CCITT-15581' is visible near the right earth station. A legend below the diagram defines: 1: Earth station, 2: Space station, 3: Hypothetical reference circuit.
+
+FIGURE 2/J.11  
+**Hypothetical reference circuit for sound-programme transmissions  
+over a system in the Fixed-Satellite Service**
+
+## ANNEX A
+
+(to Recommendation J.11)
+
+### **Illustration of an international sound-programme connection**
+
+Figure A-1/J.11 illustrates a typical international sound-programme connection in which:
+
+- point A, to be considered as the sending end of the international sound-programme connection, may be the point at which the programme originates (studio or outside location);
+- point D, to be considered as the receiving end of the international sound-programme connection, may be a programme-mixing or recording centre or a broadcasting station;
+- the local sound-programme circuit AB connects point A to the sending terminal station, point B, of the international sound-programme circuit BC;
+- the local sound-programme circuit CD connects point C, the receiving terminal station of the international sound-programme circuit BC to the point D.
+
+The hypothetical reference circuit must not be considered identical to any of the sound-programme circuits illustrated above or to those defined for maintenance purposes in [1]. However, some of these circuits may display the same structure as the hypothetical reference circuit. Such types of circuits are:
+
+- an international sound-programme connection comprising three audio sections;
+- a single sound-programme circuit made up of three audio sections.
+
+In this case, the performance standards set for the hypothetical reference circuit may be applied to these circuits.
+
+![Diagram of an international sound-programme connection showing local circuits (1), an international circuit (2), and the total international connection (3) between points A and D, with intermediate points B and C.](f9a14fbfecbd7d059226cc93677d721b_img.jpg)
+
+The diagram illustrates a horizontal line representing a sound transmission path. Points A, B, C, and D are marked along this line from left to right. Above the line, three double-headed arrows indicate different segments: '1' between A and B, '2' between B and C, and '1' between C and D. Below the line, a single long double-headed arrow labeled '3' spans from A to D. To the right of the diagram, the text 'CCITT - 15 760' is present. Below the diagram, a legend defines the segments:
+
+- 1 – local sound-programme circuits
+- 2 – international sound-programme circuit
+- 3 – international sound-programme connection
+
+Diagram of an international sound-programme connection showing local circuits (1), an international circuit (2), and the total international connection (3) between points A and D, with intermediate points B and C.
+
+FIGURE A-1/J.11  
+**An international sound-programme connection**
+
+## **Reference**
+
+- [1] *Maintenance; international sound-programme and television transmission circuits.* Recommendations of the N Series. Fascicle IV.3.
\ No newline at end of file
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+
+
+![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
+
+**J.112**
+
+(03/98)
+
+SERIES J: TRANSMISSION OF TELEVISION, SOUND  
+PROGRAMME AND OTHER MULTIMEDIA SIGNALS
+
+Interactive systems for digital television distribution
+
+---
+
+**Transmission systems for interactive cable  
+television services**
+
+ITU-T Recommendation J.112
+
+(Previously CCITT Recommendation)
+
+---
+
+# ITU-T J-SERIES RECOMMENDATIONS
+
+# **TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS**
+
+|                                                                                                 |                    |
+|-------------------------------------------------------------------------------------------------|--------------------|
+| General Recommendations                                                                         | J.1–J.9            |
+| General specifications for analogue sound-programme transmission                                | J.10–J.19          |
+| Performance characteristics of analogue sound-programme circuits                                | J.20–J.29          |
+| Equipment and lines used for analogue sound-programme circuits                                  | J.30–J.39          |
+| Digital encoders for analogue sound-programme signals                                           | J.40–J.49          |
+| Digital transmission of sound-programme signals                                                 | J.50–J.59          |
+| Circuits for analogue television transmission                                                   | J.60–J.69          |
+| Analogue television transmission over metallic lines and interconnection with radio-relay links | J.70–J.79          |
+| Digital transmission of television signals                                                      | J.80–J.89          |
+| Ancillary digital services for television transmission                                          | J.90–J.99          |
+| Operational requirements and methods for television transmission                                | J.100–J.109        |
+| <b>Interactive systems for digital television distribution</b>                                  | <b>J.110–J.129</b> |
+| Transport of MPEG-2 signals on packetised networks                                              | J.130–J.139        |
+| Measurement of the quality of service                                                           | J.140–J.149        |
+| Digital television distribution through local subscriber networks                               | J.150–J.159        |
+
+*For further details, please refer to ITU-T List of Recommendations.*
+
+# **ITU-T RECOMMENDATION J.112**
+
+# **TRANSMISSION SYSTEMS FOR INTERACTIVE CABLE TELEVISION SERVICES**
+
+# **Summary**
+
+This Recommendation "Transmission systems for interactive cable television services" extends the scope of Recommendation J.83 "Digital multi-programme systems for television, sound and data services for cable distribution" to make provision for bidirectional data over coaxial and hybrid fibre-coax cables for interactive services. Like Recommendation J.83, this Recommendation also contains several annexes in recognition of different existing media environments. The annexes in this Recommendation are intended to be read in conjunction with the corresponding annexes in Recommendation J.83.
+
+It is recommended that for the introduction of fast Internet access and/or interactive cable television services, the systems in this Recommendation be used to achieve the benefits of economies of scale and facilitate interoperability.
+
+## **Source**
+
+ITU-T Recommendation J.112 was prepared by ITU-T Study Group 9 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 18th of March 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 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 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
+
+|       |                                                                                                                                             | <i>Page</i> |
+|-------|---------------------------------------------------------------------------------------------------------------------------------------------|-------------|
+| 1     | Scope .....                                                                                                                                 | 1           |
+| 2     | References .....                                                                                                                            | 1           |
+| 2.1   | Normative References .....                                                                                                                  | 1           |
+| 2.2   | Informative references .....                                                                                                                | 3           |
+| 3     | Terms and definitions .....                                                                                                                 | 4           |
+| 4     | Abbreviations .....                                                                                                                         | 10          |
+| 5     | Interactive cable television services .....                                                                                                 | 13          |
+|       | Annex A – Interaction channel for digital video broadcasting cable television distribution systems .....                                    | 13          |
+| A.1   | Scope.....                                                                                                                                  | 13          |
+| A.2   | Normative references .....                                                                                                                  | 13          |
+| A.3   | Abbreviations .....                                                                                                                         | 13          |
+| A.4   | Referencemodel for system architecture of narrowband interaction channels in a broadcasting scenario (asymmetric interactive services)..... | 14          |
+| A.4.1 | Protocol stack model .....                                                                                                                  | 14          |
+| A.4.2 | System model .....                                                                                                                          | 14          |
+| A.5   | Interaction Channel specification for CATV networks .....                                                                                   | 16          |
+| A.5.1 | System concept.....                                                                                                                         | 16          |
+| A.5.2 | Lower physical layer specification .....                                                                                                    | 18          |
+| A.5.3 | Framing .....                                                                                                                               | 30          |
+| A.5.4 | Slot timing assignment .....                                                                                                                | 41          |
+| A.5.5 | MAC functionality.....                                                                                                                      | 47          |
+|       | Annex B – Data-over-cable radio frequency interface .....                                                                                   | 84          |
+| B.1   | Scope and purpose .....                                                                                                                     | 84          |
+| B.1.1 | Scope.....                                                                                                                                  | 84          |
+| B.1.2 | Requirements.....                                                                                                                           | 84          |
+| B.1.3 | Background .....                                                                                                                            | 85          |
+| B.2   | Functional assumptions .....                                                                                                                | 87          |
+| B.2.1 | Broadband access network .....                                                                                                              | 88          |
+| B.2.2 | Equipment assumptions .....                                                                                                                 | 88          |
+| B.2.3 | RF channel assumptions .....                                                                                                                | 89          |
+| B.2.4 | Transmission levels .....                                                                                                                   | 90          |
+| B.2.5 | Frequency inversion .....                                                                                                                   | 90          |
+| B.3   | Communication protocols .....                                                                                                               | 91          |
+| B.3.1 | Protocol stack.....                                                                                                                         | 91          |
+| B.3.2 | The MAC Forwarder .....                                                                                                                     | 94          |
+| B.3.3 | Network Layer.....                                                                                                                          | 95          |
+| B.3.4 | Above the Network Layer .....                                                                                                               | 95          |
+| B.3.5 | Data Link Layer.....                                                                                                                        | 96          |
+| B.3.6 | Physical layer .....                                                                                                                        | 97          |
+| B.4   | Physical media dependent sublayer specification.....                                                                                        | 98          |
+| B.4.1 | Scope.....                                                                                                                                  | 98          |
+| B.4.2 | Upstream .....                                                                                                                              | 98          |
+| B.4.3 | Downstream.....                                                                                                                             | 113         |
+| B.5   | Downstream transmission convergence sublayer .....                                                                                          | 117         |
+| B.5.1 | Introduction .....                                                                                                                          | 117         |
+| B.5.2 | MPEG Packet format .....                                                                                                                    | 118         |
+| B.5.3 | MPEG Header for MCNS Data-Over-Cable .....                                                                                                  | 118         |
+| B.5.4 | MPEG Payload for MCNS Data-Over-Cable .....                                                                                                 | 118         |
+| B.5.5 | Interaction with the MAC sublayer .....                                                                                                     | 119         |
+| B.5.6 | Interaction with the Physical layer.....                                                                                                    | 120         |
+| B.5.7 | MPEG Header synchronization and recovery .....                                                                                              | 121         |
+
+|                 | <i>Page</i>                                                                 |     |
+|-----------------|-----------------------------------------------------------------------------|-----|
+| B.6             | Media access control specification.....                                     | 121 |
+| B.6.1           | Introduction.....                                                           | 121 |
+| B.6.2           | MAC Frame formats.....                                                      | 122 |
+| B.6.3           | MAC Management messages .....                                               | 133 |
+| B.6.4           | Upstream bandwidth allocation .....                                         | 151 |
+| B.6.5           | Timing and synchronization .....                                            | 159 |
+| B.6.6           | Data link encryption support .....                                          | 161 |
+| B.7             | Cable modem – CMTS interaction.....                                         | 162 |
+| B.7.1           | CMTS initialization.....                                                    | 162 |
+| B.7.2           | Cable modem initialization.....                                             | 163 |
+| B.8             | Supporting future new cable modem capabilities.....                         | 179 |
+| B.8.1           | Setting up communications on an enhanced basis .....                        | 179 |
+| B.8.2           | Downloading cable modem operating software.....                             | 179 |
+| B.9             | Provision for other future capabilities.....                                | 180 |
+| B.9.1           | Anticipated physical-layer changes .....                                    | 180 |
+| B.9.2           | New network service requirements.....                                       | 181 |
+| B.9.3           | PID filtering capability.....                                               | 183 |
+| Appendix B.I    | – Well-Known Addresses.....                                                 | 184 |
+| B.I.1           | MAC addresses .....                                                         | 184 |
+| B.I.2           | MAC Service IDs.....                                                        | 184 |
+| B.I.3           | MPEG PID .....                                                              | 184 |
+| Appendix B.II   | – Parameters and constants .....                                            | 185 |
+| Appendix B.III  | – CM configuration interface specification .....                            | 186 |
+| B.III.1         | DHCP fields used by the CM .....                                            | 186 |
+| B.III.2         | CM binary configuration file format .....                                   | 186 |
+| B.III.3         | Configuration file settings .....                                           | 187 |
+| B.III.4         | Configuration file creation .....                                           | 187 |
+| B.III.5         | CM MIC calculation.....                                                     | 189 |
+| B.III.6         | CMTS MIC calculation.....                                                   | 189 |
+| B.III.7         | Registration configuration settings .....                                   | 189 |
+| B.III.8         | Encodings.....                                                              | 190 |
+| Appendix B.IV   | – MAC sublayer service definition.....                                      | 197 |
+| B.IV.1          | Service at the CM.....                                                      | 197 |
+| B.IV.2          | MAC_CM_802_DATA.request .....                                               | 197 |
+| B.IV.3          | MAC_CM_DIX_DATA.request .....                                               | 197 |
+| B.IV.4          | MAC_CM_ATM_DATA.request .....                                               | 198 |
+| B.IV.5          | MAC_CM_802_DATA.indication.....                                             | 198 |
+| B.IV.6          | MAC_CM_DIX_DATA.indication.....                                             | 198 |
+| B.IV.7          | MAC_CM_ATM_DATA.indication.....                                             | 198 |
+| B.IV.8          | MAC_CM_DATA.acknowledgment.....                                             | 198 |
+| Appendix B.V    | – Example Burst Profiles.....                                               | 199 |
+| B.V.1           | Introduction.....                                                           | 199 |
+| B.V.2           | Example preamble sequence .....                                             | 199 |
+| B.V.3           | Example Burst Profiles.....                                                 | 200 |
+| Appendix B.VI   | – Upstream modulation rates.....                                            | 209 |
+| B.VI.1          | Introduction.....                                                           | 209 |
+| B.VI.2          | Sources of narrowband ingress.....                                          | 209 |
+| B.VI.3          | Fitting data carriers within the ingress gaps .....                         | 211 |
+| Appendix B.VII  | – Example: Multiple upstream channels .....                                 | 213 |
+| Appendix B.VIII | – The data-over-cable spanning tree protocol.....                           | 214 |
+| B.VIII.1        | Background .....                                                            | 214 |
+| B.VIII.2        | Public Spanning Tree .....                                                  | 214 |
+| B.VIII.3        | Public spanning tree protocol details.....                                  | 215 |
+| B.VIII.4        | Spanning tree parameters and defaults .....                                 | 216 |
+| Annex C         | – Multimedia data transmission equipment over cable television network..... | 217 |
+| C.1             | Introduction.....                                                           | 217 |
+| C.2             | Definition of reference system and Interfaces .....                         | 217 |
+
+|       | <i>Page</i>                                          |     |
+|-------|------------------------------------------------------|-----|
+| C.3   | Protocol stacks .....                                | 218 |
+| C.3.1 | Interface A protocol stack .....                     | 218 |
+| C.3.2 | Interface A physical layer and data link layer ..... | 218 |
+| C.3.3 | Interface A network layer .....                      | 218 |
+| C.3.4 | Interface B protocol stack .....                     | 218 |
+| C.3.5 | Interface C protocol stack.....                      | 219 |
+| C.3.6 | Interface C physical layer and data link layer.....  | 219 |
+| C.3.7 | Interface C network layer .....                      | 219 |
+| C.4   | Physical layer specification.....                    | 219 |
+| C.4.1 | Upstream .....                                       | 219 |
+| C.4.2 | Downstream.....                                      | 222 |
+| C.5   | Transmission convergence sublayer specification..... | 223 |
+| C.5.1 | Introduction.....                                    | 223 |
+| C.5.2 | MPEG Packet format .....                             | 224 |
+| C.5.3 | MPEG Header .....                                    | 224 |
+| C.5.4 | Interface with MAC sublayer .....                    | 225 |
+| C.5.5 | Physical layer interaction .....                     | 226 |
+| C.5.6 | MPEG Header synchronization and recovery .....       | 226 |
+| C.6   | MAC layer specification .....                        | 226 |
+| C.6.1 | Introduction.....                                    | 226 |
+| C.6.2 | MAC Frame format .....                               | 229 |
+| C.6.3 | MAC Management message.....                          | 236 |
+
+# Introduction
+
+Digital television services have been established in many countries and the benefits of extending these to provide interactive services are widely recognized. Cable television distribution systems are particularly suited for the implementation of bidirectional data services and this Recommendation complements the system specifications in Recommendation J.83.
+
+Whilst the annexes reflect the different environments, there is substantial commonality. The services may include fast Internet access and/or interactive cable television. The transmission protocols supported include, but are not limited to IP and ATM. The reference architectures are all based on Recommendation J.110. In each case downstream transmission involves optional constant bit rate streams protected by scrambling and forward error correction, with multiplexing such that a head end can support a large number of remote stations (see A.5.1.1, B.3.6, C.4.2). Upstream transmission from the stations also involves a similar multiplex for which a Media Access Control (MAC) layer manages access on a contention or contentionless basis (see A.5.1.3, B.3.6 and C.4.1). Regarding spectrum allocation, an approach is used throughout whereby downstream transmission is at higher frequencies than upstream transmission (see A.5.1.2, B.2.3, C.4.1.4 and C.4.2.4).
+
+It should be noted that the annexes to this Recommendation describe different variations of the same protocol layers, for use in different ITU regions. Connectivity between these variations, however, can be supported by telecommunications and computer standards in the public domain, which are well-established and widely used.
+
+It should be further noted that there exists two Supplements to the J-series Recommendations related to Rec. J.112 which are entitled:
+
+- Supplement 1 – Example of linking options between annexes of ITU-T Recommendation J.112 and annexes of ITU-T Recommendation J.83;
+- Supplement 2 – Guidelines for the use of Annex A of Recommendation J.112 "Transmission systems for interactive cable television services"; Example of Digital Video Broadcasting (DVB) interaction channel for cable television distribution.
+
+# TRANSMISSION SYSTEMS FOR INTERACTIVE CABLE TELEVISION SERVICES
+
+(Geneva, 1998)
+
+# 1 Scope
+
+This Recommendation "Transmission systems for interactive cable television services" extends the scope of Recommendation J.83 "Digital multi-programme systems for television, sound and data services for cable distribution" to make provision for bidirectional data over hybrid fibre-coax cables for interactive services. Like Recommendation J.83, this Recommendation also contains several annexes in recognition of different existing media environments. The annexes in this Recommendation are intended to be read in conjunction with the corresponding annexes in Recommendation J.83.
+
+Annex A is based on work done in Europe and is related to a wider set of options such as Recommendation J.111 and should provide a suitable basis for further developments.
+
+Annex B is based on work done in North America and should provide a suitable basis for future developments.
+
+Annex C is based on work done in Japan and should provide a suitable basis for future developments.
+
+Whilst Annexes A, B and C correspond to A, B and C in Recommendation J.83, there is substantial commonality in the services and protocols supported. The reference architectures are also based on Recommendation J.110. There is therefore the possibility that, in application, the features chosen for use with the transmission system described in a particular annex of Recommendation J.83 are not limited to only the corresponding annex 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; 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.
+
+## 2.1 Normative References
+
+- [EN 50201] ETSI EN 50201:1997, *Interfaces for DVB-IRDs*. (Ref. Annex A.)
+- [EN 300 421] ETSI EN 300 421, *Digital Broadcasting systems for television, sound and data services – Framing structure, channel coding and modulation for 11/12 satellite services. (DVB-S spec)*. (Ref. Annex A.)
+- [ETS 300 802] ETSI ETS 300 802: *Digital Video Broadcasting (DVB) – Network Independent Protocols for interactive Services*. (Ref. Annex A.)
+- [ISO/IEC 8825] ISO/IEC 8825:1990, *Information technology – Open Systems Interconnection – Specification of the Basic Encoding Rules for Abstract Syntax Notation One (ASN.1)*. (Ref. Annex B.)
+- [ISO/IEC 8802-2] ISO/IEC 8802-2:1994 (IEEE Std 802.2:1994), *Information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Specific requirements – Part 2: Logical link control*. (Ref. Annex B.)
+- [ISO/IEC 8802-3] ISO/IEC 8802-3:1996 (IEEE Std 802.3:1996), *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*. (Ref. Annex B.)
+
+|                   |                                                                                                                                                                                                                                                                                                            |
+|-------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| [ISO/IEC 10038]   | ISO/IEC 10038:1993 (ANSI/IEEE Std 802.1D:1993), <i>Information technology – Telecommunications and information exchange between systems – Local area networks – Media Access Control (MAC) bridges</i> . (Ref. Annex B.)                                                                                   |
+| [ISO/IEC 10039]   | ISO/IEC 10039:1991, <i>Information technology – Open Systems Interconnection – Local area networks – Medium Access Control (MAC) service definition</i> . (Ref. Annex B.)                                                                                                                                  |
+| [ISO/IEC 15802-1] | ISO/IEC 15802-1:1995, <i>Information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Common specifications – Part 1: Medium Access Control (MAC) service definition</i> . (Ref. Annex B.)                                                |
+| [ITU-T H.222.0]   | ITU-T Recommendation H.222.0 (1995)   ISO/IEC 13818-1:1996, <i>Information technology – Generic coding of moving pictures and associated audio information: Systems</i> . (Ref. Annex B.)                                                                                                                  |
+| [ITU-T I.361]     | ITU-T Recommendation I.361 (1995), <i>B-ISDN ATM layer specification</i> . (Ref. Annex A.)                                                                                                                                                                                                                 |
+| [ITU-T I.363]     | ITU-T Recommendation I.363, <i>B-ISDN ATM Adaptation Layer specification</i> . (Ref. Annex A.)                                                                                                                                                                                                             |
+| [ITU-T J.83 A]    | ITU-T Recommendation J.83 (Annex A) (1997), <i>Digital multi-programme systems for television, sound and data services for cable distribution (Digital multi-programme System A)</i> . (Ref. Annex A.)                                                                                                     |
+| [ITU-T J.83 B]    | ITU-T Recommendation J.83 (Annex B) (1997), <i>Digital multi-programme systems for television, sound and data services for cable distribution (Digital multi-programme System B)</i> . (Ref. Annex B.)                                                                                                     |
+| [ITU-T J.83 C]    | ITU-T Recommendation J.83 (Annex C) (1997), <i>Digital multi-programme systems for television, sound and data services for cable distribution (Digital multi-programme System C)</i> . (Ref. Annex C.)                                                                                                     |
+| [ITU-T J.110]     | ITU-T Recommendation J.110 (1997), <i>Basic principles for a worldwide common family of systems for the provision of interactive television services</i> .                                                                                                                                                 |
+| [CCITT V.21]      | CCITT Recommendations V.21 (1984), 300 bits per second duplex modem standardized for use in the general switched telephone network. (Ref. Annex A.)                                                                                                                                                        |
+| [CCITT V.22]      | CCITT Recommendation V.22 (1988), 1200 bits per second duplex modem standardized for use in the general switched telephone network and on point-to-point 2-wire leased telephone-type circuits. (Ref. Annex A.)                                                                                            |
+| [CCITT V.22 bis]  | CCITT Recommendation V.22 bis (1988), <i>2400 bits per second duplex modem using the frequency division technique standardized for use on the general switched telephone network and on point-to-point 2-wire leased telephone-type circuits</i> . (Ref. Annex A.)                                         |
+| [CCITT V.23]      | CCITT Recommendation V.23 (1988), <i>600/1200-baud modem standardized for use in the general switched telephone network</i> . (Ref. Annex A.)                                                                                                                                                              |
+| [ITU-T V.25]      | ITU-T Recommendation V.25 (1996), <i>Automatic answering equipment and general procedures for automatic calling equipment on the general switched telephone network including procedures for disabling of echo control devices for both manually and automatically established calls</i> . (Ref. Annex A.) |
+| [ITU-T V.32]      | ITU-T Recommendation V.32 (1993), <i>A family of 2-wire, duplex modems operating at data signalling rates of up to 9600 bit/s for use on the general switched telephone network and on leased telephone-type circuits</i> . (Ref. Annex A.)                                                                |
+| [CCITT V.32 bis]  | CCITT Recommendation V.32 bis (1991), <i>A duplex modem operating at data signalling rates of up to 14 400 bit/s for use on the general switched telephone network and on leased point-to-point 2-wire telephone-type circuits</i> . (Ref. Annex A.)                                                       |
+| [ITU-T V.34]      | ITU-T Recommendation V.34 (1998), <i>A modem operating at data signalling rates of up to 33 600 bit/s for use on the general switched telephone network and on leased point-to-point 2-wire telephone-type circuits</i> . (Ref. Annex A.)                                                                  |
+
+- [ITU-T V.42] ITU-T Recommendation V.42 (1996), *Error-correcting procedures for DCEs using asynchronous-to-synchronous conversion*. (Ref. Annex A.)
+- [ITU-T X.25] ITU-T Recommendation X.25 (1996), *Interface between Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE) for terminals operating in the packet mode and connected to public data networks by dedicated circuit*. (Ref. Annex B.)
+- [ITU-T Z.100] ITU-T Recommendation Z.100 (1993), *CCITT Specification and Description Language (SDL)*. (Ref. Annex B.)
+- [RFC-791] POSTEL (J.), Internet Protocol, IETF RFC-791 (MIL STD 1777), September, 1981. (Ref. Annex B.)
+- [RFC-826] PLUMMER (D.), Ethernet Address Resolution Protocol: Or converting network protocol addresses to 48-bit Ethernet address for transmission on Ethernet hardware, November, 1982. (Ref. Annex B.)
+- [RFC-868] HARRENSTIEN (K.) and POSTEL (J.), Time Protocol, IETF RFC-868, May 1983. (Ref. Annex B.)
+- [RFC-1042] POSTEL (J.) and REYNOLDS (J.), A Standard for the Transmission of IP Datagrams over IEEE 802 Networks, IETF RFC-1042, February, 1988. (Ref. Annex B.)
+- [RFC-1058] HEDRICK (C.), Routing Information Protocol, IETF RFC-1058, June, 1988 . (Ref. Annex B.)
+- [RFC-1157] SCHOFFSTALL (M.), FEDOR (M.), DAVIN (J.) and CASE (J.), A Simple Network Management Protocol (SNMP), IETF RFC-1157, May, 1990. (Ref. Annex B.)
+- [RFC-1350] SOLLINGS (K.), The TFTP Protocol (Revision 2), IETF RFC-1350, July, 1992. (Ref. Annex B.)
+- [RFC-1493] DECKER (E.), LANGILLE (P.), RIJSINGHANI (A.) and McCLOGHRIE (K.), Definitions of Managed Objects for Bridges, July, 1993, (Obsoletes RFC-1286). (Ref. Annex B.)
+- [RFC-1533] ALEXANDER (S.) and DROMS (R.), DHCP Options and BOOTP Vendor Extensions, IETF RFC-1533, October, 1993. (Ref. Annex B.)
+- [RFC-1541] DROMS (R.), Dynamic Host Configuration Protocol, IETF RFC-1541, October, 1993. (Ref. Annex B.)
+- [RFC-1633] BRADEN (R.), CLARK (D.) and SHENKER (S.), Integrated Services in the Internet Architecture: An Overview, IETF RFC-1633, June, 1994. (Ref. Annex B.)
+- [RFC-1812] BAKER (F.), Requirements for IP Version 4 Routers, IETF RFC-1812, June, 1995. (Ref. Annex B.)
+- [RFC-2104] KRAWCZYK (H.), BELLARE (M.) and CANETTI (R.), HMAC: Keyed-Hashing for Message Authentication, IETF RFC-2104, February, 1997. (Ref. Annex B.)
+
+## 2.2 Informative references
+
+- [91/263/EEC] 91/263/EEC Directive on Terminal equipment. (Ref. Annex A.)
+- [CableLabs1] Two-Way Cable Television System Characterization, Cable Television Laboratories, Inc., April 12, 1995. (Ref. Annex B.)
+- [CableLabs2] Digital Transmission Characterization of Cable Television Systems, Cable Television Laboratories, Inc., November, 1994. (Ref. Annex B.)
+- [DAVIC] DAVIC Specification, DAVIC System Reference Model. (Ref. Annex A.)
+- [DIX] Ethernet Protocol Version 2.0, Digital, Intel, Xerox, 1982. (Ref. Annex B.)
+- [DVB-A008] DVB-A008, Commercial requirements for asymmetric interactive services supporting broadcast to the home with narrowband return channels, October, 1995. (Ref. Annex A.)
+- [ETS 300 800] ETS 300 800, Digital Video Broadcasting (DVB) – DVB interaction channel for Cable TV distribution systems (CATV). (Ref. Annex A.)
+
+|               |                                                                                                                                                                                    |
+|---------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| [IEEE 802]    | IEEE Std 802:1990, Local and Metropolitan Area Networks: Overview and Architecture. (Ref. Annex B.)                                                                                |
+| [IEEE 802.1Q] | IEEE Draft Standard 802.1Q/D4., Draft Standard for Virtual Bridged Local Area Networks, December 20, 1996. (Ref. Annex B.)                                                         |
+| [IPS-SP-401]  | F-Connector Specification, Society of Cable Television Engineers. (Ref. Annex B.)                                                                                                  |
+| [IS-6]        | EIA Interim Standard IS-6 (1983), Recommended Cable TV Channel Identification Plan. (Ref. Annex B.)                                                                                |
+| [JCTEA1]      | Multiplex System for Digital Cable Television, JCTEA STD-002. (Ref. Annex C.)                                                                                                      |
+| [JCTEA2]      | Receiver for Cable Television, JCTEA STD-004. (Ref. Annex C.)                                                                                                                      |
+| [MCNS2]       | Data-Over-Cable Service Specifications, Security System Interface Specification, SP-SSI-I01-970506. (Ref. Annex B.)                                                                |
+| [MCNS3]       | Data-Over-Cable Service Interface Specifications, Cable Modem Termination System – Network-Side Interface Specification SP-CMTS-NSI-I01-960702. (Ref. Annex B.)                    |
+| [MCNS4]       | Data-Over-Cable Service Interface Specifications, Cable Modem to Customer Premises Equipment Interface Specification SP-CMCI-I01-960702. (Ref. Annex B.)                           |
+| [MCNS5]       | Data-Over-Cable Service Interface Specifications, Operations Support System Interfaces SP-OSSI-I01-970403. (Ref. Annex B.)                                                         |
+| [MCNS6]       | Data-Over-Cable Service Interface Specifications, Cable Modem Telephone Return Interface Specification SP-CMTRI-I01-970804. (Ref. Annex B.)                                        |
+| [MCNS7]       | Data-Over-Cable Service Interface Specifications, Removable Security Module Interface Specifications, SP-RSMI-I01-980204. (Ref. Annex B.)                                          |
+| [MCNS8]       | Data-Over-Cable Service Interface Specifications, Baseline Privacy Interface SP-BPI-I01-970609. (Ref. Annex B.)                                                                    |
+| [NCTA]        | NCTA Recommended Practices for measurement on Cable Television Systems – National Cable Television Association, Washington DC, 2nd Edition, revised October, 1993. (Ref. Annex B.) |
+| [SMS]         | The Spectrum Management Application (SMA) and the Common Spectrum Management Interface (CSMI), Time Warner Cable, December 24, 1995. (Ref. Annex B.)                               |
+
+# 3 Terms and definitions
+
+This Recommendation defines the following terms.
+
+**3.1 Address Resolution Protocol (ARP):** A protocol of the IETF for converting network addresses to 48-bit Ethernet addresses.
+
+**3.2 American National Standards Institute (ANSI):** A US standards body.
+
+**3.3 Asynchronous Transfer Mode (ATM):** A protocol for the transmission of a variety of digital signals using uniform 53-byte cells.
+
+**3.4 availability:** In cable television systems, availability is the long-term ratio of the actual RF channel operation time to scheduled RF channel operation time (expressed as a percent value) and is based on a Bit Error Rate (BER) assumption.
+
+**3.5 Bridge Protocol Data Unit (BDU):** Spanning tree protocol messages as defined in [ISO/IEC 10038].
+
+**3.6 broadcast addresses:** A predefined destination address that denotes the set of all data network service access points.
+
+**3.7 burst error second:** Any Errored Second containing at least 100 errors.
+
+- 3.8 Cable Modem (CM):** A modulator-demodulator at subscriber locations intended for use in conveying data communications on a cable television system (see Annex B). Called IIM in Annex A and MH in Annex C.
+- 3.9 Cable Modem Termination System (CMTS):** Cable modem termination system, located at the cable television system headend or distribution hub, which provides complementary functionality to the cable modems to enable data connectivity to a wide-area network (see Annex A). Called INA in Annex A and MC in Annex C.
+- 3.10 cable modem termination system; Network Side Interface (CMTS-NSI):** The interface, defined in [MCNS3], between a CMTS and the equipment on its network side (see Annex B). Called INA in Annex A and MC in Annex C.
+- 3.11 Cable Modem to CPE Interface (CMCI):** The interface, defined in [MCNS4], between a CM and CPE.
+- 3.12 carrier hum modulation:** The peak-to-peak magnitude of the amplitude distortion relative to the RF carrier signal level due to the fundamental and low-order harmonics of the power-supply frequency.
+- 3.13 carrier-to-Noise Ratio (C/N or CNR):** The square of the ratio of the root mean square (rms) of the voltage of the digitally-modulated RF carrier to the rms of the continuous random noise voltage in the defined measurement bandwidth. (If not specified explicitly, the measurement bandwidth is the symbol rate of the digital modulation).
+- 3.14 carrier related band** (applies to Annexes B and C only): A frequency bandwidth of spacing television channels on a cable television system in exact 6 MHz increments.
+- 3.15 Composite Second Order Beat (CSO):** The peak of the average level of distortion products due to second-order non-linearities in cable system equipment.
+- 3.16 Composite Triple Beat (CTB):** The peak of the average level of distortion components due to third-order non-linearities in cable system equipment.
+- 3.17 cyclic redundancy check:** A method of error detection using cyclic code.
+- 3.18 cross-modulation:** A form of television signal distortion where modulation from one or more television channels is imposed on another channel or channels.
+- 3.19 customer:** See End User.
+- 3.20 Customer Premises Equipment (CPE):** Equipment at the end user's premises; may be provided by the end user or the service provider.
+- 3.21 data link layer:** Layer 2 in the Open System Interconnection (OSI) architecture; the layer that provides services to transfer data over the transmission link between open systems.
+- 3.22 distribution hub:** A location in a cable television network which performs the functions of a Headend for customers in its immediate area, and which receives some or all of its television program material from a Master Headend in the same metropolitan or regional area; see, for example, [MCNS1].
+- 3.23 downstream:** In cable television, the direction of transmission from the headend to the subscriber.
+- 3.24 drop cable:** Coaxial cable that connects to a residence or service location from a directional coupler (tap) on the nearest coaxial feeder cable.
+- 3.25 Dynamic Host Configuration Protocol (DHCP):** An Internet protocol used for assigning network-layer (IP) addresses.
+- 3.26 dynamic range:** The ratio between the greatest signal power that can be transmitted over a multichannel analogue transmission system without exceeding distortion or other performance limits, and the least signal power that can be utilized without exceeding noise, error rate or other performance limits.
+
+- 3.27 Electronic Industries Association (EIA):** A voluntary body of manufacturers which, among other activities, prepares and publishes standards.
+- 3.28 end user:** A human being, organization, or telecommunications system that accesses the network in order to communicate via the services provided by the network.
+- 3.29 errored second:** Any one second interval containing at least one bit error.
+- 3.30 extended subsplit:** A frequency division scheme that allows bidirectional traffic on a single coaxial cable. E.G. in North America, reverse path signals come to the Headend from 5 to 42 MHz, and forward path signals go from the Headend from 50 or 54 MHz to the upper frequency limit.
+- 3.31 feeder cable:** Coaxial cables that run along streets within the served area and connect between the individual taps which serve the customer drops.
+- 3.32 Fiber Distributed Data Interface (FDDI):** A fiber-based LAN standard.
+- 3.33 fiber node:** A point of interface between a fiber trunk and the coaxial distribution.
+- 3.34 forward channel:** The direction of RF signal flow away from the headend toward the end user; equivalent to Downstream.
+- 3.35 group delay:** The difference in transmission time between the highest and lowest of several frequencies through a device, circuit or system.
+- 3.36 guard time:** Minimum time allocated between bursts in the upstream, referenced from the symbol center of the last symbol of a burst to the symbol center of the first symbol of the following burst.
+- 3.37 Harmonic Related Carrier (HRC):** A method of spacing television channels on a cable television system in exact 6 MHz increments, with all carrier frequencies harmonically related to a common reference.
+- 3.38 headend:** The central location on the cable network that is responsible for injecting broadcast video and other signals in the downstream direction. See also Master Headend, Distribution Hub.
+- 3.39 header:** Protocol control information located at the beginning of a protocol data unit.
+- 3.40 High Frequency (HF):** Used in Annex B to refer to the entire subsplit (5-30 MHz) and extended subsplit (5-42 MHz) band used in reverse channel communications over the cable television network.
+- 3.41 high return:** A frequency division scheme that allows bi-directional traffic on a single coaxial cable. Reverse channel signals propagate to the headend above the downstream passband.
+- 3.42 hum modulation:** Undesired modulation of the television visual carrier by the fundamental or low-order harmonics of the power supply frequency, or other low-frequency disturbances.
+- 3.43 Hybrid Fiber/Coax (HFC) system:** A broadband bidirectional shared-media transmission system using fiber trunks between the headend and the fiber nodes, and coaxial distribution from the fiber nodes to the customer locations.
+- 3.44 interactive interface module (see Annex A):** Called CM in Annex B and MH in Annex C.
+- 3.45 Incremental Related Carriers (IRC):** A method of spacing NTSC television channels on a cable television system in which all channels except 5 and 6 correspond to the standard channel plan, used to reduce composite triple beat distortions.
+- 3.46 Institute of Electrical and Electronic Engineers (IEEE):** A voluntary organization which, among other things, sponsors standards committees and is accredited by the American National Standards Institute.
+- 3.47 interleave:** An error correction method that enables the correction of burst noise induced errors.
+
+- 3.48 International Electrotechnical Commission (IEC):** An international standards body.
+- 3.49 International Organization for Standardization (ISO):** An international standards body, commonly known as the International Standards Organization.
+- 3.50 Internet Control Message Protocol (ICMP):** An Internet network-layer protocol.
+- 3.51 Internet Engineering Task Force (IETF):** A body responsible, among other things, for developing standards used in the Internet. See also request for comments.
+- 3.52 impulse noise:** Noise characterized by non-overlapping transient disturbances.
+- 3.53 Internet Protocol (IP):** An Internet network-layer protocol, defined by the IETF.
+- 3.54 Japan Cable Television Engineering Association (JCTEA):** A body responsible for developing standards concerning cable television systems in Japan.
+- 3.55 latency:** The time, expressed in quantity of symbols, taken for a signal element to pass through a device.
+- 3.56 layer:** A subdivision of the Open System Interconnection (OSI) architecture, constituted by subsystems of the same rank.
+- 3.57 Local Area Network (LAN):** A non-public data network in which serial transmission is used for direct data communication among data stations located on the user's premises.
+- 3.58 Logical Link Control (LLC) procedure:** In a Local Area Network (LAN) or a Metropolitan Area Network (MAN), that part of the protocol that governs the assembling of data link layer frames and their exchange between data stations, independent of how the transmission medium is shared.
+- 3.59 MAC service access point:** See B. 6.1.2.
+- 3.60 master headend:** A headend which collects television program material from various sources by satellite, microwave, fiber and other means, and distributes this material to Distribution Hubs in the same metropolitan or regional area. A Master Headend may also perform the functions of a Distribution Hub for customers in its own immediate area; see, for example, [MCNS1].
+- 3.61 multimedia center equipment:** Equipment located at cable television headend, which provides complementary functionality to the Multimedia Home Equipment to enable data connectivity to a wide-area network. Called CMTS in Annex B and INA in Annex A.
+- 3.62 Mean Time to Repair (MTTR):** In cable television systems, the MTTR is the average elapsed time from the moment a loss of RF channel operation is detected up to the moment the RF channel operation is fully restored.
+- 3.63 Media Access Control (MAC) address:** The “built-in” hardware address of a device connected to a shared medium.
+- 3.64 Media Access Control (MAC) procedure:** In a subnetwork, that part of the protocol that governs access to the transmission medium independent of the physical characteristics of the medium, but taking into account the topological aspects of the subnetworks, in order to enable the exchange of data between nodes. MAC procedures include framing, error protection, and acquiring the right to use the underlying transmission medium.
+- 3.65 Media Access Control (MAC) sublayer:** The part of the data link layer that supports topology dependent functions and uses the services of the Physical Layer to provide services to the Logical Link Control (LLC) sublayer.
+- 3.66 multimedia home equipment:** A modulator-demodulator at subscriber locations intended for use in conveying data communications on a cable television system (see Annex C). Called CMTS in Annex B and INA in Annex A.
+- 3.67 micro-reflections:** Echoes in the forward transmission path due to departures from ideal amplitude and phase characteristics.
+
+- 3.68 mid split:** A frequency division scheme that allows bi-directional traffic on a single coaxial cable, e.g. in North America, reverse channel signals propagate to the headend from 5 to 108 MHz, the forward path signals go from the Headend from 162 MHz to the upper frequency limit, and the diplex crossover band is located from 108 to 162 MHz.
+- 3.69 mini-slot:** In Annex B, a mini-slot is an integer multiple of 6.25-microsecond increments. The relationship between mini-slots, bytes and time ticks is described in B.6.5.4.
+- 3.70 Moving Picture Experts Group (MPEG):** A voluntary body which develops standards for digital compressed moving pictures and associated audio.
+- 3.71 Multimedia Cable Network System (MCNS) partners:** A consortium of Comcast Cable Communications, Inc., Cox Communications, Tele-Communications, Inc., and Time Warner Cable, interested in deploying high-speed data communications systems on cable television systems.
+- 3.72 multipoint access:** User access in which more than one terminal equipment is supported by a single network termination.
+- 3.73 multipoint connection:** A connection among more than two data network terminations.
+- 3.74 National Cable Television Association (NCTA):** A voluntary association of cable television operators which, among other things, provides guidance on measurements and objectives for cable television systems in the USA.
+- 3.75 National Television Systems Committee (NTSC):** Committee which defined the analog colour television broadcast standard used in North America.
+- 3.76 network layer:** Layer 3 in the Open System Interconnection (OSI) architecture; the layer that provides services to establish a path between open systems.
+- 3.77 network management:** The functions related to the management of data link layer and physical layer resources and their stations across the data network supported by the hybrid fiber/coax system.
+- 3.78 Open Systems Interconnection (OSI):** A framework of ISO standards for communication between different systems made by different vendors, in which the communications process is organized into seven different categories that are placed in a layered sequence based on their relationship to the user. Each layer uses the layer immediately below it and provides a service to the layer above. Layers 7 through 4 deal with end-to-end communication between the message source and destination, and layers 3 through 1 deal with network functions.
+- 3.79 Organizationally Unique Identifier (OUI):** A three octet IEEE assigned identifier that OUI can be used to generate Universal LAN MAC addresses and Protocol Identifiers per ANSI/IEEE Std 802 for use in Local and Metropolitan Area Network applications.
+- 3.80 Packet Identifier (PID):** A unique integer value used to identify elementary streams of a program in a single- or multi-program MPEG-2 stream.
+- 3.81 Physical (PHY) layer:** Layer 1 in the Open System Interconnection (OSI) architecture; the layer that provides services to transmit bits or groups of bits over a transmission link between open systems and which entails electrical, mechanical and handshaking procedures.
+- 3.82 Physical Media Dependent (PMD) sublayer:** A sublayer of the Physical Layer which is concerned with transmitting bits or groups of bits over particular types of transmission link between open systems and which entails electrical, mechanical and handshaking procedures.
+- 3.83 Program Specific Information (PSI):** In MPEG-2, normative data necessary for the demultiplexing of Transport Streams and the successful regeneration of programs.
+- 3.84 program stream:** In MPEG-2, a multiplex of variable-length digital video and audio packets from one or more program sources having a common time-base.
+
+- 3.85 protocol:** A set of rules and formats that determines the communication behaviour of layer entities in the performance of the layer functions.
+- 3.86 Quadrature Amplitude Modulation (QAM):** A method of modulating digital signals onto a radio-frequency carrier signal involving both amplitude and phase coding.
+- 3.87 Quaternary Phase-Shift Keying (QPSK):** A method of modulating digital signals onto a radio-frequency carrier signal using four phase states to code two digital bits.
+- 3.88 Radio Frequency (RF):** In cable television systems, this refers to electromagnetic signals typically in the range 5 to 1000 MHz.
+- 3.89 Reed-Solomon code:** A forward error correction code located before interleaving that enables correction of errors induced by burst noise.
+- 3.90 Request for Comments (RFC):** A technical policy document of the IETF; these documents can be accessed on the World Wide Web at <http://ds.internic.net/ds/rfcindex.html>.
+- 3.91 return loss:** The parameter describing the attenuation of a guided wave signal (e.g. via a coaxial cable) returned to a source by a device or medium resulting from reflections of the signal generated by the source.
+- 3.92 reverse channel:** The direction of signal flow towards the headend, away from the subscriber; equivalent to Upstream.
+- 3.93 roll off:** A coefficient of cosine roll off function that determines the frequency characteristics of the filter.
+- 3.94 Routing Information Protocol (RIP):** A protocol of the IETF for exchanging routing information about IP networks and subnets.
+- 3.95 Service Access Point (SAP):** The point at which services are provided by one layer, or sublayer, to the layer immediately above it.
+- 3.96 Service Data Unit (SDU):** Information that is delivered as a unit between peer service access points.
+- 3.97 Simple Network Management Protocol (SNMP):** A network management protocol of the IETF.
+- 3.98 Spectrum Management System (SMS):** A system, defined in [SMS], for managing the RF cable spectrum.
+- 3.99 sublayer:** A subdivision of a layer in the Open System Interconnection (OSI) reference model.
+- 3.100 subnetwork:** Subnetworks are physically formed by connecting adjacent nodes with transmission links.
+- 3.101 Subnetwork Access Protocol (SNAP):** An extension of the LLC header to accommodate the use of IEEE 802 type networks as IP networks.
+- 3.102 subscriber:** See End User.
+- 3.103 subsplit:** A frequency-division scheme that allows bi-directional traffic on a single cable, e.g. in North America, reverse path signals come to the Headend from 5 to 30 MHz (up to 42 MHz on Extended Subsplit systems), and forward path signals go from the headend from 50 or 54 MHz to the upper frequency limit of the cable network.
+- 3.104 subsystem:** An element in a hierarchical division of an open system that interacts directly with elements in the next higher division or the next lower division of that open system.
+- 3.105 systems management:** Functions in the application layer related to the management of various Open Systems Interconnection (OSI) resources and their status across all layers of the OSI architecture.
+
+- 3.106 tick:** Time intervals that are the reference for upstream mini-slot definition and upstream transmission times.
+- 3.107 tilt:** Maximum difference in transmission gain of a cable television system over a given bandwidth (typically the entire forward operating frequency range).
+- 3.108 transit delay:** The time difference between the instant at which the first bit of a PDU crosses one designated boundary, and the instant at which the last bit of the same PDU crosses a second designated boundary.
+- 3.109 Transmission Control Protocol (TCP):** A transport-layer Internet protocol which ensures successful end-to-end delivery of data packets without error, as defined by the IETF.
+- 3.110 transmission convergence sublayer:** A sublayer of the Physical Layer that provides an interface between the Data Link Layer and the PMD Sublayer.
+- 3.111 transmission link:** The physical unit of a subnetwork that provides the transmission connection between adjacent nodes.
+- 3.112 transmission medium:** The material on which information signals may be carried; e.g., optical fiber, coaxial cable, and twisted wire pairs.
+- 3.113 transmission system:** The interface and transmission medium through which peer physical layer entities transfer bits.
+- 3.114 transmit on/off ratio:** In multiple-access systems, the ratio between the signal powers sent to line when transmitting and when not transmitting.
+- 3.115 transport stream:** In MPEG-2, a packet based method of multiplexing one or more digital video and audio streams having one or more independent time bases into a single stream.
+- 3.116 Trivial File Transfer Protocol (TFTP):** An Internet protocol for transferring files without the requirement for user names and passwords that is typically used for automatic downloads of data and software.
+- 3.117 trunk cable:** Cables that carry the signal from the headend to groups of subscribers. The cables can be either coaxial or fiber depending on the design of the system.
+- 3.118 Type/Length/Value (TLV):** An encoding of three fields, in which the first field indicates the type of element, the second the length of the element, and the third field, the value.
+- 3.119 upstream:** The direction from the subscriber location toward the headend.
+
+# 4 Abbreviations
+
+This Recommendation uses the following abbreviations:
+
+|              |                                                         |
+|--------------|---------------------------------------------------------|
+| (C/N or CNR) | Carrier-to-Noise Ratio                                  |
+| ANSI         | American National Standards Institute                   |
+| ARP          | Address Resolution Protocol                             |
+| ATM          | Asynchronous Transfer Mode                              |
+| BC           | Broadcast Channel                                       |
+| BPDU         | Bridge Protocol Data Unit                               |
+| BRA          | Basic Rate Access                                       |
+| CATV         | Cable Television                                        |
+| CM           | Cable Modem, IIM, MH                                    |
+| CMCI         | Cable Modem to CPE Interface                            |
+| CMTS         | Cable Modem Termination System                          |
+| CMTS-NSI     | Cable Modem Termination System – Network Side Interface |
+
+|            |                                                  |
+|------------|--------------------------------------------------|
+| CPE        | Customer Premises Equipment                      |
+| CRC        | Cyclic Redundancy Check                          |
+| CSO        | Composite Second Order beat                      |
+| CTB        | Composite Triple Beat                            |
+| DA         | Destination Address                              |
+| DAVIC      | Digital Audiovisual Council                      |
+| DCE        | Data Communication Equipment                     |
+| DHCP       | Dynamic Host Configuration Protocol              |
+| DOC        | Data over Cable                                  |
+| DTE        | Data Termination Equipment                       |
+| DTMF       | Dual Tone Multifrequency (dialling mode)         |
+| DVB        | Digital Video Broadcasting                       |
+| EH or EHDR | Extended Header                                  |
+| EIA        | Electronic Industries Association                |
+| FC         | Frame Control                                    |
+| FDDI       | Fiber Distributed Data Interface                 |
+| FDM        | Frequency Division Multiplex                     |
+| FDMA       | Frequency Division Multiple Access               |
+| FEC        | Forward Error Correction                         |
+| GSTN       | General Switched Telephone Network               |
+| GT         | Global Time                                      |
+| HCS        | Header Check Sequence                            |
+| HF         | High Frequency                                   |
+| HFC        | Hybrid Fiber/Coax system                         |
+| HRC        | Harmonic Related Carrier                         |
+| IB         | In-Band                                          |
+| IC         | Interaction Channel                              |
+| ICMP       | Internet Control Message Protocol                |
+| IE         | Information Element                              |
+| IEC        | International Electrotechnical Commission        |
+| IEEE       | Institute of Electrical and Electronic Engineers |
+| IETF       | Internet Engineering Task Force                  |
+| IIM        | Interactive Interface Module                     |
+| INA        | Interactive Network Adapter                      |
+| IP         | Internet Protocol                                |
+| IQ         | In-phase and Quadrature Components               |
+| IRC        | Incremental Related Carriers (IRC)               |
+| IRD        | Integrated Receiver Decoder                      |
+| ISDN       | Integrated Services Digital Network              |
+| ISO        | International Organization for Standardization   |
+| JCTEA      | Japan Cable Television Engineering Association   |
+| LAN        | Local Area Network                               |
+
+|       |                                                |
+|-------|------------------------------------------------|
+| LEN   | Length (in bytes unless otherwise stated)      |
+| LFSR  | Linear Feedback Shift Register                 |
+| LLC   | Logical Link Control procedure                 |
+| LSB   | Least Significant Bit                          |
+| LT    | Local time                                     |
+| MAC   | Media Access Control                           |
+| MC    | Multimedia Center Equipment                    |
+| MCNS  | Multimedia Cable Network System                |
+| MH    | Multimedia Home equipment                      |
+| MMDS  | Multi-channel Multi-point Distribution Systems |
+| MPEG  | Moving Picture Experts Group                   |
+| MSAP  | MAC Service Access Point                       |
+| MSB   | Most Significant Bit                           |
+| MTTR  | Mean Time to Repair                            |
+| NCTA  | National Cable Television Association          |
+| NIU   | Network Interface Unit                         |
+| NSAP  | Network Service Access Point                   |
+| NTSC  | National Television Systems Committee          |
+| OOB   | Out of Band                                    |
+| OSI   | Open Systems Interconnection                   |
+| OUI   | Organization Unique Identifier                 |
+| PHY   | Physical (PHY) layer                           |
+| PID   | Packet Identifier                              |
+| PM    | Pulse Modulation                               |
+| PMD   | Physical Media Dependent sublayer              |
+| PSI   | Program Specific Information                   |
+| PSTN  | Public Switched Telephone Network              |
+| QAM   | Quadrature Amplitude Modulation                |
+| QOS   | Quality of Service                             |
+| QPSK  | Quaternary Phase-Shift Keying                  |
+| REQ   | Request indicator used in Annex B.             |
+| RF    | Radio Frequency                                |
+| RFC   | Request for Comments                           |
+| RIP   | Routing Information Protocol                   |
+| RNG   | Ranging                                        |
+| RTD   | Round Trip Delay                               |
+| SAP   | Service Access Point                           |
+| SDU   | Service Data Unit                              |
+| SID   | Service Identifier                             |
+| SMATV | Satellite Master Antenna Television            |
+| SMS   | Spectrum Management System                     |
+| SNAP  | Subnetwork Access Protocol                     |
+| SNMP  | Simple Network Management Protocol             |
+
+|      |                                   |
+|------|-----------------------------------|
+| STB  | Set-Top Box                       |
+| STU  | Set-Top Unit                      |
+| SYNC | Synchronization                   |
+| TC   | Transmission Convergence sublayer |
+| TCP  | Transmission Control Protocol     |
+| TDMA | Time Division Multiplex Access    |
+| TFTP | Trivial File Transfer Protocol    |
+| TLV  | Type/Length/Value                 |
+| TS   | Transport Stream                  |
+| UCC  | Upstream Channel Change           |
+| UCD  | Upstream Channel Descriptor       |
+
+# 5 Interactive cable television services
+
+It is recommended that for interactive cable television services, the appropriate systems described in the annexes be used in conjunction with the relevant cable distribution systems described in Recommendation J.83.
+
+# Annex A
+
+## Interaction channel for digital video broadcasting cable television distribution systems
+
+## A.1 Scope
+
+This annex is derived from work done on the provisioning of interaction channels for CATV networks in Europe [ETS 300 800].
+
+It is not intended to specify a return channel solution associated to each broadcast system because the interoperability of different delivery media to transport the return channel is desirable.
+
+These solutions provided for interaction channel for CATV networks are a part of a wider set of alternatives to implement interactive services for digital video broadcasting systems.
+
+## A.2 Normative references
+
+See common part of this Recommendation.
+
+## A.3 Abbreviations
+
+See the common part of this Recommendation.
+
+## A.4 Reference model for system architecture of narrowband interaction channels in a broadcasting scenario (asymmetric interactive services)
+
+### A.4.1 Protocol stack model
+
+For asymmetric interactive services supporting broadcast to the home with narrowband return channel, a simple communications model consists of the following layers:
+
+- **physical layer:** Where all the physical (electrical) transmission parameters are defined;
+- **transport layer:** Defines all the relevant data structures and communication protocols like data containers, etc.;
+- **application layer:** Is the interactive application software and runtime environments (e.g. home shopping application, script interpreter, etc.).
+
+This specification addresses the lower two layers (the physical and transport) leaving the application layer open to competitive market forces.
+
+A simplified model of the OSI layers was adopted to facilitate the production of specifications for these nodes. Figure A.1 points out the lower layers of the simplified model and identifies some of the key parameters for the lower two layers. Following the user requirements for interactive services, no attempt will be made to consider higher layers in this specification.
+
+This specification addresses the CATV network specific aspects only. The network independent protocols will be specified separately [ETS 300 802].
+
+![Diagram of the layer structure for a generic system reference model. It shows a stack of layers. At the top are 'Proprietary layers'. Below them are 'Higher medium layers' and 'Network independent protocols'. The next layer is a box containing 'Access mechanism' and 'Packet structure'. Below this is another box containing 'Modulation', 'Channel coding', 'Frequency range', 'Filtering', 'Equalization', and 'Power'. To the right of these two boxes is the label 'Network dependent protocols'.](90ddf538ef276510e2b631f7b96654e6_img.jpg)
+
+|                                                                                       |                               |
+|---------------------------------------------------------------------------------------|-------------------------------|
+| Proprietary layers                                                                    |                               |
+| Higher medium layers                                                                  | Network independent protocols |
+| Access mechanism<br>Packet structure                                                  | Network dependent protocols   |
+| Modulation<br>Channel coding<br>Frequency range<br>Filtering<br>Equalization<br>Power |                               |
+
+Diagram of the layer structure for a generic system reference model. It shows a stack of layers. At the top are 'Proprietary layers'. Below them are 'Higher medium layers' and 'Network independent protocols'. The next layer is a box containing 'Access mechanism' and 'Packet structure'. Below this is another box containing 'Modulation', 'Channel coding', 'Frequency range', 'Filtering', 'Equalization', and 'Power'. To the right of these two boxes is the label 'Network dependent protocols'.
+
+**Figure A.1/J.112 – Layer structure for generic system reference model**
+
+### A.4.2 System model
+
+Figure A.2 shows the system model which is to be used within DVB for interactive services.
+
+In the system model, two channels are established between the Service provider and the User:
+
+- **Broadcast Channel (BC):** A unidirectional broadband Broadcast Channel including video, audio and data. BC is established from the service provider to the users. It may include the Forward Interaction path.
+- **Interaction Channel (IC):** A Bidirectional Interaction Channel is established between the service provider and the user for interaction purposes. It is formed by:
+  - **Return Interaction path (Return Channel):** From the User to the Service Provider. It is used to make requests to the service provider or to answer questions. It is a narrowband channel. Also commonly known as return channel.
+  - **Forward Interaction path:** From the service provider to the user. It is used to provide some sort of information by the service provider to the user and any other required communication for the interactive service provision. It may be embedded into the broadcast channel. It is possible that this channel is not required in some simple implementations which make use of the Broadcast Channel for the carriage of data to the user.
+
+The user terminal is formed by the Network Interface Unit (NIU) [consisting of the Broadcast Interface Module (BIM) and the Interactive Interface Module (IIM)] and the Set-Top Unit (STU). The user terminal provides interface for both broadcast and interaction channels. The interface between the user terminal and the interaction network is via the Interactive Interface Module.
+
+![A generic system Reference Model for interactive systems diagram showing the flow between Broadcast Channel (DVB transmission systems), Broadcasting delivery media, Broadcast network adaptor, Broadcast service provider, Interactive service provider, Interactive network adaptor, Interaction network, and the Set-Top Box (STB) containing Broadcast interface module, Interactive interface module, and Set-Top Unit (STU).](365b54f616aff249b4e6c0edafdcb9b3_img.jpg)
+
+The diagram illustrates a generic system Reference Model for interactive systems. It shows the flow of data and control between various components:
+
+- Broadcast Channel (DVB transmission systems)**: The source of broadcast data, connected to the **Broadcast service provider** and **Broadcast network adaptor**.
+- Broadcast service provider**: Connected to the **Broadcast network adaptor** and the **Interactive service provider**.
+- Broadcast network adaptor**: Connects the **Broadcast service provider** to the **Broadcasting delivery media**.
+- Broadcasting delivery media**: The cloud representing the broadcast transmission path, connected to the **Broadcast network adaptor** and the **Set-Top Box (STB)**.
+- Set-Top Box (STB)**: Contains three main components:
+  - Broadcast interface module**: Receives data from the **Broadcasting delivery media** and sends it to the **Set-Top Unit (STU)**.
+  - Interactive interface module (can be external to STB)**: Connected to the **Set-Top Unit (STU)** and the **Interactive network adaptor**.
+  - Set-Top Unit (STU)**: The central processing unit, connected to the **Broadcast interface module**, the **Interactive interface module**, and the **End user**.
+- End user**: Represented by a person icon, interacting with the **Set-Top Unit (STU)**.
+- Interaction network**: A cloud representing the interactive network, connected to the **Interactive network adaptor**.
+- Interactive network adaptor**: Connects the **Interactive service provider** and the **Interactive interface module** to the **Interaction network**.
+- Interactive service provider**: Connected to the **Broadcast service provider** and the **Interactive network adaptor**.
+- Return interaction path**: The path from the **Interaction network** back to the **Interactive service provider**.
+- Forward interaction path**: The path from the **Interactive service provider** to the **Interaction network**.
+- Interaction channels**: The bidirectional communication between the **Set-Top Box (STB)** and the **Interaction network**.
+
+Labels at the bottom indicate network dependencies:
+
+- Network independent**: Associated with the **Broadcast Channel (DVB transmission systems)**, **Broadcasting delivery media**, **Set-Top Box (STB)**, and **End user**.
+- Network independent**: Associated with the **Interaction network**.
+- Interaction Channel**: Associated with the **Interactive service provider** and **Interactive network adaptor**.
+- Network independent**: Associated with the **Interactive service provider** and **Interactive network adaptor**.
+
+A generic system Reference Model for interactive systems diagram showing the flow between Broadcast Channel (DVB transmission systems), Broadcasting delivery media, Broadcast network adaptor, Broadcast service provider, Interactive service provider, Interactive network adaptor, Interaction network, and the Set-Top Box (STB) containing Broadcast interface module, Interactive interface module, and Set-Top Unit (STU).
+
+T0904350-57/d001
+
+Figure A.2/J.112 – A generic system Reference Model for interactive systems
+
+## **A.5 Interaction Channel specification for CATV networks**
+
+The CATV infrastructures can support the implementation of the Return Channel for interactive services suitable for DVB broadcasting systems.
+
+CATV can be used to implement interactive services in the DVB environment, providing a bidirectional communication path between the user terminal and the service provider.
+
+### **A.5.1 System concept**
+
+The interactive system is composed of Forward Interaction path (downstream) and Return Interaction path (upstream). The general concept is to use downstream transmission from the INA to the NIUs to provide synchronization and information to all NIUs. This allows the NIUs to adapt to the network and send synchronized information upstream.
+
+Upstream transmission is divided into time slots which can be used by different users, using the technique of Time Division Multiple Access (TDMA). One downstream channel is used to synchronize up to 8 upstream channels, which are all divided into time slots. A counter at the INA is sent periodically to the NIUs, so that all NIUs work with the same clock. This gives the opportunity to the INA to assign time slots to different users.
+
+Three major access modes are provided with this system. The first one is based on contention access, which lets users send information at any time with the risk to have a collision with other user's transmissions. The second and third modes are contention-less based, where the INA either provides a finite amount of slots to a specific NIU, or a given bit rate requested by a NIU until the INA stops the connection on NIU's demand. These access modes are dynamically shared among time slots, which allows NIUs to know when contention based transmission is or is not allowed. This is to avoid a collision for the two contention-less based access modes.
+
+Periodically, the INA will indicate to new users that they have the possibility to go through sign-on procedure, in order to give them the opportunity to synchronize their clock to the network clock, without risking collisions with already active users. This is done by leaving a larger time interval for new users to send their information, taking into account the propagation time required from the INA to the NIUs and back.
+
+#### **A.5.1.1 Out-of-band/In-band principle**
+
+This interactive system is based either on Out-of-Band (OOB) or In-Band (IB) downstream signalling. However, Set-Top Boxes do not need to support both systems.
+
+In the case of OOB signalling, a Forward Interaction path is added. This path is reserved for interactivity data and control information only. The presence of this added Forward Information path is in that case mandatory. However, it is also possible to send higher bit rate downstream information through a DVB-C channel whose frequency is indicated in the Forward Information path.
+
+In the case of IB signalling, the Forward Information path is embedded into the MPEG-2 TS of a DVB-C channel. Note that it is not mandatory to include the Forward Information path in all DVB-C channels.
+
+Both systems can provide the same quality of service. However, the overall system architecture will differ between networks using IB Set-Top Boxes and OOB Set-Top Boxes. Note also that both types of systems may exist on the same networks under the condition that different frequencies are used for each system.
+
+#### **A.5.1.2 Spectrum allocation**
+
+Figure A.3 indicates a possible spectrum allocation. Although not mandatory, a guideline is provided to use the following preferred frequency ranges, 70-130 MHz and/or 300-862 MHz for the Forward Interaction path (downstream OOB) and 5-65 MHz for the Return Interaction path (upstream), or parts thereof. To avoid filtering problems in the bidirectional RF amplifiers and in the Set-Top Boxes, the upper limit 65 MHz for the upstream flow shall not be used together with the lower limit 70 MHz for the downstream flow in the same system. For passive networks, the frequency range 5-65 MHz could be used bidirectionally. Furthermore, to avoid intermediate frequency impairments of Set-Top Boxes as well as analogue receivers in the same network, it could be necessary to leave out some parts of the range 5-65 MHz which includes the intermediate frequency ranges of these appliances.
+
+NOTE – To fix detailed limits for the usable frequency range(s), future investigations concerning the intermediate frequency immunity of receivers must be carried through.
+
+![Figure A.3/J.112 – DVB preferred frequency ranges for CATV interactive systems. The diagram shows a frequency spectrum from 5 to 862 MHz. The 'Downstream' direction is indicated by an upward arrow, and the 'Upstream' direction by a downward arrow. The spectrum is divided into several regions: 5-65 MHz for 'QPSK interactive 1 or 2 MHz or 200 kHz upstream channels'; 70-130 MHz for 'DVB-C QAM 7/8 MHz channels'; 300-862 MHz for 'DVB-C QAM 7/8 MHz channels'; and 'QPSK interactive 1 or 2 MHz downstream OOB channels' located between the DVB-C QAM channels. The x-axis is labeled 'Freq. (MHz)' and has a tick mark at 862. A small code 'T0904360-97/d002' is visible in the bottom right corner of the diagram area.](1d3994bfe548ae7545d57df703e32a02_img.jpg)
+
+Figure A.3/J.112 – DVB preferred frequency ranges for CATV interactive systems. The diagram shows a frequency spectrum from 5 to 862 MHz. The 'Downstream' direction is indicated by an upward arrow, and the 'Upstream' direction by a downward arrow. The spectrum is divided into several regions: 5-65 MHz for 'QPSK interactive 1 or 2 MHz or 200 kHz upstream channels'; 70-130 MHz for 'DVB-C QAM 7/8 MHz channels'; 300-862 MHz for 'DVB-C QAM 7/8 MHz channels'; and 'QPSK interactive 1 or 2 MHz downstream OOB channels' located between the DVB-C QAM channels. The x-axis is labeled 'Freq. (MHz)' and has a tick mark at 862. A small code 'T0904360-97/d002' is visible in the bottom right corner of the diagram area.
+
+**Figure A.3/J.112 – DVB preferred frequency ranges for CATV interactive systems**
+
+#### A.5.1.3 FDM/TDMA multiple access
+
+A multiple access scheme is defined in order to have different users share the same transmission media. Downstream information is sent broadcast to all users of the networks. Thus, an address assignment exists for each user which allows the INA to send information singlecast to one particular user. Two addresses are stored in Set-Top Boxes in order to identify users on the network:
+
+- MAC address: It is a 48-bit value representing the unique MAC address of the NIU. This MAC address may be hard coded in the NIU or be provided by external source.
+- NSAP address: It is a 160-bit value representing a network address. This address is provided by higher layers during communication.
+
+Upstream information may come from any user in the network and must therefore also be differentiated at the INA using the set of addresses defined above.
+
+Upstream and OOB downstream channels are divided into separate channels of 1 or 2 MHz bandwidth for downstream and 1 or 2 MHz or 200 kHz for upstream. Each downstream channel contains a synchronization frame used by up to 8 different upstream channels, whose frequencies are indicated by the Media Access Control (MAC) protocol.
+
+Within upstream channels, users send packets with TDMA type access. This means that each channel is shared by many different users, who can either send packets with a possibility of collisions when this is allowed by the INA, or request transmission and use the packets assigned by the INA to each user specifically. Assuming each channel can therefore accommodate thousands of users at the same time, the upstream bandwidth can easily be used by all users present on the network at the same time.
+
+The TDMA technique utilizes a slotting methodology which allows the transmit start times to be synchronized to a common clock source. Synchronizing the start times increases message throughput of this signalling channel since the message packets do not overlap during transmission. The period between sequential start times are identified as slots. Each slot is a point in time when a message packet can be transmitted over the signalling link.
+
+The time reference for slot location is received via the downstream channels generated at the Delivery System and received simultaneously by all Set-Top Units. Note that this time reference is not sent in the same way for OOB and IB signalling. Since all NIUs reference the same time base, the slot times are aligned for all NIUs. However, since there is propagation delay in any transmission network, a time base ranging method accommodates deviation of transmission due to propagation delay.
+
+Since the TDMA signalling link is used by NIUs that are engaged in interactive sessions, the number of available message slots on this channel is dependent on the number of simultaneous users. When messaging slots are not in use, an NIU may be assigned multiple message slots for increased messaging throughput. Additional slot assignments are provided to the NIU from the downstream signalling information flow.
+
+There are different access modes for the upstream slots:
+
+- Reserved slots with fixed rate reservation (Fixed Rate Access: the user has a reservation of one or several time slots in each frame enabling, e.g. for voice, audio).
+- Reserved slots with dynamic reservation (Reservation Access: the user sends control information announcing his demand for transmission capacity. He gets grants for the use of slots).
+- Contention based slots (these slots are accessible for every user. Collision is possible and solved by a contention resolution protocol).
+- Ranging slots (these slots are used upstream to measure and adjust the time delay and the power).
+
+These slots may be mixed on a single carrier to enable different services on one carrier only. If one carrier is assigned to one specific service, only those slot types will be used which are needed for this service. Therefore a terminal can be simplified to respond to only those slot types assigned to the service.
+
+#### **A.5.1.4 Bit rates and Framing**
+
+For the interactive downstream OOB channel, a rate of 1.544 Mbit/s or 3.088 Mbit/s may be used. For downstream IB channels, no other constraints than those specified in the DVB-C specifications exist, but a guideline would be to use rates multiples of 8 kbit/s.
+
+Downstream OOB channels continuously transmit a frame based on T1 type framing, in which some information is provided for synchronization of upstream slots. Downstream IB channels transmit some MPEG-2 TS packets with a specific PID for synchronization of upstream slots (at least one packet containing synchronization information must be sent in every period of 3 ms).
+
+For upstream transmission, the INA can indicate three types of transmission rates to users, specifically 3.088 Mbit/s, 1.544 Mbit/s or 256 kbit/s. The INA is responsible for indicating which rate may be used by NIUs. It would imply all NIUs to be able to either transmit with 256 kbit/s, 1.544 Mbit/s, or 3.088 Mbit/s. Only the implementation of one of these bit rates would be mandatory.
+
+Upstream framing consists of packets of 512 bits (256 symbols) which are sent in a bursty mode from the different users present on the network. The upstream slot rates are 6000 upstream slots/s when the upstream data rate is 3.088 Mbit/s, 3000 upstream slots/s when the upstream data rate is 1.544 Mbit/s and 500 upstream slots/s when the upstream data rate is 256 kbit/s.
+
+### **A.5.2 Lower physical layer specification**
+
+In this subclause, detailed information is given on the lower physical layer specification. Figures A.4 and A.5 show the conceptual block diagrams for implementation of the present specification.
+
+#### **A.5.2.1 Forward interaction path (downstream OOB)**
+
+##### **A.5.2.1.1 Frequency range (downstream OOB)**
+
+The frequency range is not specified as mandatory although a guideline is provided to use the following preferred frequency ranges, 70-130 MHz and/or 300-862 MHz or parts thereof, in order to simplify the tuner of the NIU. Frequency stability shall be in the range  $\pm 50$  ppm measured at the upper limit of the frequency range.
+
+![Conceptual block diagram for the NIU OOB transceiver. The diagram shows two main processing paths connected to a central 'MAC protocol carrier and clock and synchronization' block. The top path is for receiving data from the RF channel, and the bottom path is for transmitting data to the RF cable channel. The central block provides synchronization signals to both paths.](aaf3e6e44cdeabd6d1df869c5f392ea1_img.jpg)
+
+Cable NIU
+
+The diagram illustrates the internal architecture of a Cable NIU OOB transceiver. At the top, the receive path starts with 'From RF channel' entering an 'RF physical interface and QPSK demodulator'. The signal then passes through a 'Matched filter', a 'Differential decoder', a 'Self synchronized derandomizer and framing', a 'Bit to byte mapping' block, a 'Convolutional de-interleaver', and finally a 'Reed-Solomon decoder' to produce 'ATM data out'. The bottom path is the transmit path, starting with 'ATM data in' entering a 'Reed-Solomon encoder'. The signal then goes through 'Byte to bit mapping', a 'Randomizer', a 'Differential encoder', 'Addition of unique word', and a 'QPSK burst modulator' to output 'To RF cable channel'. A central 'MAC protocol carrier and clock and synchronization' block is connected to both paths, providing necessary timing and control signals.
+
+T0904370-97/d003
+
+Conceptual block diagram for the NIU OOB transceiver. The diagram shows two main processing paths connected to a central 'MAC protocol carrier and clock and synchronization' block. The top path is for receiving data from the RF channel, and the bottom path is for transmitting data to the RF cable channel. The central block provides synchronization signals to both paths.
+
+Figure A.4/J.112 – Conceptual block diagram for the NIU OOB transceiver
+
+![Conceptual block diagram for the OOB head-end transceiver. The diagram shows two main processing paths connected to a central 'MAC protocol management carrier and clock and synchronization generator' block. The top path is for transmitting data from the baseband interface to the RF cable channel, and the bottom path is for receiving data from the RF cable channel. The central block provides management and synchronization signals to both paths.](a149b400127a3e3e50b3c98d27c5935c_img.jpg)
+
+Cable Head-end
+
+The diagram illustrates the internal architecture of an OOB head-end transceiver. The top path is the transmit path, starting with 'ATM data in' from a 'Baseband interface to: Service provider source multiplexers, etc.'. The signal passes through a 'BB physical interface', a 'Reed-Solomon encoder', a 'Convolutional interleaver', 'Framing', 'Byte to bit mapping', a 'Randomizer', a 'Differential encoder', and a 'QPSK modulator' to output 'To RF cable channel'. The bottom path is the receive path, starting with 'From RF cable channel' entering a 'QPSK burst demodulator'. The signal then passes through a 'Differential decoder', a 'Derandomizer', a 'Bit to byte mapping' block, and a 'Reed-Solomon decoder' to produce 'ATM data out'. A central 'MAC protocol management carrier and clock and synchronization generator' block is connected to both paths, providing management and synchronization signals.
+
+T0904380-97/d004
+
+Conceptual block diagram for the OOB head-end transceiver. The diagram shows two main processing paths connected to a central 'MAC protocol management carrier and clock and synchronization generator' block. The top path is for transmitting data from the baseband interface to the RF cable channel, and the bottom path is for receiving data from the RF cable channel. The central block provides management and synchronization signals to both paths.
+
+Figure A.5/J.112 – Conceptual block diagram for the OOB head-end transceiver
+
+![Conceptual block diagram for the IB NIU transceiver. The diagram shows two main data paths. The top path is for MPEG-2 TS data out, starting from a BB physical interface, passing through Sync, inversion and energy disposal removal, Reed-Solomon decoder (204, 188), Convolutional deinterleaver, Symbol to byte mapping, Differential decoder, Matched filter and equalizer, and finally an RF physical interface and QAM demodulator from an RF channel. The bottom path is for ATM data in, starting from a Reed-Solomon encoder (59, 53), passing through Byte to bit mapping, Randomizer, Differential encoder, Addition of unique word, and a QPSK burst modulator to an RF cable channel. A central MAC protocol management block for carrier and clock and synchronization is connected to both paths.](8c348bf9c2c81b018017ae1d19506a9a_img.jpg)
+
+T0904390-97/d005
+
+Conceptual block diagram for the IB NIU transceiver. The diagram shows two main data paths. The top path is for MPEG-2 TS data out, starting from a BB physical interface, passing through Sync, inversion and energy disposal removal, Reed-Solomon decoder (204, 188), Convolutional deinterleaver, Symbol to byte mapping, Differential decoder, Matched filter and equalizer, and finally an RF physical interface and QAM demodulator from an RF channel. The bottom path is for ATM data in, starting from a Reed-Solomon encoder (59, 53), passing through Byte to bit mapping, Randomizer, Differential encoder, Addition of unique word, and a QPSK burst modulator to an RF cable channel. A central MAC protocol management block for carrier and clock and synchronization is connected to both paths.
+
+Figure A.6/J.112 – Conceptual block diagram for the IB NIU transceiver
+
+![Conceptual block diagram for the IB head-end transceiver. The diagram shows two main data paths. The top path is for MPEG-2 Data in from a baseband interface to service provider source multiplexers, etc., passing through a BB physical interface, Inversion and randomization, Reed-Solomon encoder (204, 188), Convolutional interleaver (1-12 bytes), Byte to m-tuple mapping, Differential encoding, and an RF physical interface and QAM modulator to an RF channel. The bottom path is for ATM data out, starting from a QPSK burst demodulator from an RF channel, passing through Differential decoder, Derandomizer, Bit to byte mapping, and a Reed-Solomon decoder (59, 53). A central MAC protocol management block for carrier and clock and synchronization is connected to both paths.](b235edb1dbe659e2782c9a0e47775ca4_img.jpg)
+
+T0904400-97/d006
+
+Conceptual block diagram for the IB head-end transceiver. The diagram shows two main data paths. The top path is for MPEG-2 Data in from a baseband interface to service provider source multiplexers, etc., passing through a BB physical interface, Inversion and randomization, Reed-Solomon encoder (204, 188), Convolutional interleaver (1-12 bytes), Byte to m-tuple mapping, Differential encoding, and an RF physical interface and QAM modulator to an RF channel. The bottom path is for ATM data out, starting from a QPSK burst demodulator from an RF channel, passing through Differential decoder, Derandomizer, Bit to byte mapping, and a Reed-Solomon decoder (59, 53). A central MAC protocol management block for carrier and clock and synchronization is connected to both paths.
+
+Figure A.7/J.112 – Conceptual block diagram for the IB head-end transceiver
+
+##### A.5.2.1.2 Modulation and mapping (downstream OOB)
+
+QPSK modulation is used as a means of encoding digital information over wireline or fibre transmission links. The method is a subset of Phase Shift Keying (PSK) which is a subset of Phase Modulation (PM). Specifically QPSK is a four level use of digital Phase Modulation (PM). Quadrature signal representations involve expressing an arbitrary phase sinusoidal waveform as a linear combination of a cosine wave and a sine wave with zero starting phases.
+
+QPSK systems require the use of differential encoding and corresponding differential detection. This is a result of the receivers having no method of determining if a recovered reference is a sine reference or a cosine reference. In addition, the polarity of the recovered reference is uncertain.
+
+Differential encoding transmits the information in encoded phase differences between the two successive signals. The modulator processes the digital binary symbols to achieve differential encoding and then transmits the absolute phases. The differential encoding is implemented at the digital level.
+
+The differential encoder shall accept bits A, B in sequence, and generate phase changes as shown in Table A.1:
+
+**Table A.1/J.112 – Phase changes associated with bit A, B**
+
+| A | B | Phase Change |
+|---|---|--------------|
+| 0 | 0 | None         |
+| 0 | 1 | +90°         |
+| 1 | 1 | 180°         |
+| 1 | 0 | –90°         |
+
+In serial mode, A arrives first. The outputs I, Q from the differential encoder map to the phase states as in Figure A.8.
+
+![Figure A.8/J.112 – Mapping for the QPSK constellation (downstream OOB). The diagram shows a 2D coordinate system with a horizontal I-axis and a vertical Q-axis. Four points are plotted: '01' in the upper-left quadrant, '11' in the upper-right quadrant, '00' in the lower-left quadrant, and '10' in the lower-right quadrant. A small label 'T0904410-97/d007' is present below the plot.](1033ab90cd19fd4c5901966aeec07a86_img.jpg)
+
+Figure A.8/J.112 – Mapping for the QPSK constellation (downstream OOB). The diagram shows a 2D coordinate system with a horizontal I-axis and a vertical Q-axis. Four points are plotted: '01' in the upper-left quadrant, '11' in the upper-right quadrant, '00' in the lower-left quadrant, and '10' in the lower-right quadrant. A small label 'T0904410-97/d007' is present below the plot.
+
+**Figure A.8/J.112 – Mapping for the QPSK constellation (downstream OOB)**
+
+The phase changes can also be expressed by the following formulas (assuming the constellation is mapped from I and Q as shown in A.5.2.2.2):
+
+$$\begin{cases} A_k = \overline{(I_{k-1} \oplus Q_{k-1})} \times (Q_{k-1} \oplus Q_k) + \overline{(I_k \oplus Q_{k-1})} \times (I_k \oplus I_{k-1}) \\ B_k = (I_{k-1} \oplus Q_{k-1}) \times (I_{k-1} \oplus I_k) + (I_{k-1} \oplus Q_k) \times (Q_k \oplus Q_{k-1}) \end{cases}$$
+
+where  $k$  is the time index.
+
+I/Q amplitude imbalance shall be less than 1.0 dB, and phase imbalance less than 2.0°.
+
+##### A.5.2.1.3 Shaping filter (downstream OOB)
+
+The time-domain response of a square-root raised-cosine pulse with excess bandwidth parameter  $\alpha$  is given by:
+
+$$g(t) = \frac{\sin\left[\frac{\pi t}{T}(1-\alpha)\right] + \frac{4\alpha t}{T} \cos\left[\frac{\pi t}{T}(1+\alpha)\right]}{\frac{\pi t}{T} \left[1 - \left(\frac{4\alpha t}{T}\right)^2\right]}$$
+
+where  $T$  is the symbol period.
+
+The output signal shall be defined as:
+
+$$S(t) = \sum_n [I_n \times g(t - nT) \times \cos(2\pi f_c t) - Q_n \times g(t - nT) \times \sin(2\pi f_c t)]$$
+
+with  $I_n$  and  $Q_n$  equal to  $\pm 1$ , independently from each other, and  $f_c$  the QPSK modulator's carrier frequency.
+
+The QPSK modulator divides the incoming bit stream so that bits are sent alternately to the in-phase modulator I and the out-of-phase modulator Q. These same bit streams appear at the output of the respective phase detectors in the demodulator where they are interleaved back into a serial bit stream.
+
+The occupied bandwidth of a QPSK signal is given by the equation:
+
+$$\text{Bandwidth} = \frac{f_b}{2} (1 + \alpha)$$
+
+$f_b$  = bit rate
+
+$\alpha$  = excess bandwidth = 0.30
+
+For both bit rates: 1.544 Mbit/s (Grade A) and 3.088 Mbit/s (Grade B), the Power Spectrum at the QPSK transmitter shall comply to the Power Spectrum Mask given in Table A.2 and Figure A.9. The Power Spectrum Mask shall be applied symmetrically around the carrier frequency.
+
+**Table A.2/J.112 – QPSK downstream transmitter Power Spectrum**
+
+| $ (f - f_c) / f_N $ | Power Spectrum   |
+|---------------------|------------------|
+| $\leq 1 - \alpha$   | $0 \pm 0.25$ dB  |
+| at 1                | $-3 \pm 0.25$ dB |
+| at $1 + \alpha$     | $\leq -21$ dB    |
+| $\geq 2$            | $\leq -40$ dB    |
+
+![Figure A.9/J.112 – QPSK downstream transmitter Power Spectrum. This is a graph showing the power spectrum H(f) versus the normalized frequency |(f - f_c) / f_N|. The y-axis is labeled H(f) and has markers at 0 dB, -3 dB, -21 dB, and -40 dB. The x-axis is labeled |(f - f_c) / f_N| and has markers at 1 - alpha, 1, 1 + alpha, and 2. The power spectrum is flat at 0 dB from 0 to 1 - alpha. At 1 - alpha, it begins to roll off. At f_N (x=1), the power is -3 dB. At 1 + alpha, the power is -21 dB. At x=2, the power is -40 dB. For x > 2, the power is below -40 dB. The graph includes annotations for 'In-band ripple r_m < 0.5 dB' and 'Nyquist ripple r_N < 0.5 dB' in the flat region, and 'Out-of-band rejection > 40 dB' for the region beyond x=2. A small code 'T0904420-97/d008' is visible in the bottom right corner of the graph area.](f12fd90263d4329f529373b914096dec_img.jpg)
+
+Figure A.9/J.112 – QPSK downstream transmitter Power Spectrum. This is a graph showing the power spectrum H(f) versus the normalized frequency |(f - f\_c) / f\_N|. The y-axis is labeled H(f) and has markers at 0 dB, -3 dB, -21 dB, and -40 dB. The x-axis is labeled |(f - f\_c) / f\_N| and has markers at 1 - alpha, 1, 1 + alpha, and 2. The power spectrum is flat at 0 dB from 0 to 1 - alpha. At 1 - alpha, it begins to roll off. At f\_N (x=1), the power is -3 dB. At 1 + alpha, the power is -21 dB. At x=2, the power is -40 dB. For x > 2, the power is below -40 dB. The graph includes annotations for 'In-band ripple r\_m < 0.5 dB' and 'Nyquist ripple r\_N < 0.5 dB' in the flat region, and 'Out-of-band rejection > 40 dB' for the region beyond x=2. A small code 'T0904420-97/d008' is visible in the bottom right corner of the graph area.
+
+**Figure A.9/J.112 – QPSK downstream transmitter Power Spectrum**
+
+QPSK systems require the use of differential encoding and corresponding differential detection. This is a result of the receivers having no method of determining if a recovered reference is a sine reference or a cosine reference. In addition, the polarity of the recovered reference is uncertain.
+
+Differential encoding transmits the information in encoded phase differences between the two successive signals. The modulator processes the digital binary symbols to achieve differential encoding and then transmits the absolute phases. The differential encoding is implemented at the digital level.
+
+##### A.5.2.1.4 Randomizer (downstream OOB)
+
+After addition of the FEC bytes (see A.5.3), all of the 1.544 Mbit/s (or 3.088 Mbit/s) data is passed through a six register Linear Feedback Shift Register (LFSR) randomizer to ensure a random distribution of ones and zeroes. The generating polynomial is:  $x^6 + x^5 + 1$ . Byte/serial conversion shall be MSB first. A complementary self-synchronizing de-randomizer is used in the receiver to recover the data.
+
+![Diagram of a Randomizer (Figure A.10/J.112).](4f148853ae68fdcf5e43f7604cab457d_img.jpg)
+
+The diagram shows a randomizer circuit. A 'Serial input' enters from the top and is split. One path goes to an XOR gate (represented by a circle with a '+' sign). The output of this XOR gate is the 'Serial output'. The other path from the input goes into a chain of six square boxes representing shift register stages. The output of the sixth stage is fed back to the second XOR gate in the chain. The outputs of the first and second XOR gates are combined at the second XOR gate. The output of the second XOR gate is fed back to the first XOR gate. The diagram is labeled 'T0904430-97/d009'.
+
+Diagram of a Randomizer (Figure A.10/J.112).
+
+Figure A.10/J.112 – Randomizer
+
+![Diagram of a De-randomizer (Figure A.11/J.112).](98e54d5540b2efe3e24af3cf936bc4ea_img.jpg)
+
+The diagram shows a de-randomizer circuit. A 'Serial input' enters from the top and is split. One path goes to a chain of six square boxes representing shift register stages. The output of the sixth stage is fed back to the second XOR gate (represented by a circle with a '+' sign). The outputs of the first and second XOR gates are combined at the second XOR gate. The output of the second XOR gate is fed back to the first XOR gate. The output of the first XOR gate is the 'Serial output'. The diagram is labeled 'T0904440-97/d010'.
+
+Diagram of a De-randomizer (Figure A.11/J.112).
+
+Figure A.11/J.112 – De-randomizer
+
+##### A.5.2.1.5 Bit rate (downstream OOB)
+
+The bit rate shall be 1.544 Mbit/s or 3.088 Mbit/s. Only one of the bit rates is mandatory in the NIU. Symbol rate accuracy should be within  $\pm 50$  ppm.
+
+##### A.5.2.1.6 Receiver power level (downstream OOB)
+
+The receiver power level shall be in the range 42-75 dBmicroV (RMS) ( $75 \Omega$ ) at its input.
+
+##### A.5.2.1.7 Summary (downstream OOB)
+
+| Transmission Rate            | 1.544 Mbit/s for Grade A<br>3.088 Mbit/s for Grade B                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+|------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------|---|--------------|---|---|------|---|---|------|---|---|------|---|---|------|
+| Modulation                   | Differentially encoded QPSK                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| Transmit Filtering           | Filtering is alpha = 0.30 square root raised cosine                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| Channel Spacing              | 1 MHz for Grade A<br>2 MHz for Grade B                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| Frequency Step Size          | 250 kHz (center frequency granularity)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| Randomization                | <p>After addition of the FEC bytes, all of the 1.544 Mbit/s (or 3.088 Mbit/s) data is passed through a six register Linear Feedback Shift Register (LFSR) randomizer to ensure a random distribution of ones and zeroes.</p> <p>The generating polynomial is: <math>x^6 + x^5 + 1</math>.</p> <p>Byte/serial conversion shall be MSB first.</p> <p>A complementary self-synchronizing de-randomizer is used in the receiver to recover the data.</p>                                                                                                                                                                                                             |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| Differential Encoding        | <p>The differential encoder shall accept bits A, B in sequence, and generate phase changes as follows:</p> <table border="0" style="margin-left: 20px;"> <thead> <tr> <th style="text-align: left; text-decoration: underline;">A</th> <th style="text-align: left; text-decoration: underline;">B</th> <th style="text-align: left; text-decoration: underline;">Phase-Change</th> </tr> </thead> <tbody> <tr> <td>0</td> <td>0</td> <td>None</td> </tr> <tr> <td>0</td> <td>1</td> <td>+90°</td> </tr> <tr> <td>1</td> <td>1</td> <td>180°</td> </tr> <tr> <td>1</td> <td>0</td> <td>–90°</td> </tr> </tbody> </table> <p>In serial mode, A arrives first.</p> | A            | B | Phase-Change | 0 | 0 | None | 0 | 1 | +90° | 1 | 1 | 180° | 1 | 0 | –90° |
+| A                            | B                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | Phase-Change |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| 0                            | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | None         |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| 0                            | 1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | +90°         |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| 1                            | 1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 180°         |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| 1                            | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | –90°         |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| Signal Constellation         | <p>The outputs I, Q from the differential encoder map to the phase states as in Figure A.12.</p> <div style="text-align: center;"> <img alt="Figure A.12/J.112: Signal Constellation diagram showing four points in the I-Q plane. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'. The points are: 01 in the top-left quadrant, 11 in the top-right quadrant, 00 in the bottom-left quadrant, and 10 in the bottom-right quadrant. A small label 'T0904450-97/d011' is at the bottom right of the diagram." data-bbox="823 1220 1110 1480" src="da4689ba847c2f4c5c713dbd36de987f_img.jpg"/> <p><b>Figure A.12/J.112</b></p> </div>      |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| Frequency Range              | Recommended but not mandatory 70 to 130 MHz and/or 300 to 862 MHz                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| Frequency Stability          | ± 50 ppm measured at the upper limit of the frequency range                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| Symbol Rate Accuracy         | ± 50 ppm                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| Carrier Suppression          | > 30 dB                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| I/Q Amplitude Imbalance      | < 1.0 dB                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| I/Q Phase Imbalance          | < 2.0°                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| Receive Power Level at input | 42-75 dBmicroV (RMS) (75 Ω)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+| Transmit Spectral Mask       | A common mask for both bit rates: 1.544 Mbit/s (Grade A) and 3.088 Mbit/s (Grade B) is given in Table A.2 and in Figure A.9                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |              |   |              |   |   |      |   |   |      |   |   |      |   |   |      |
+
+##### A.5.2.1.8 Bit error rate downstream OOB (informative)
+
+Bit error rate at the NIU should be less than  $10^{-10}$  (after error correction, i.e. 1 error in 2 hours at 1.5 Mbit/s) at  $C/N > 20$  dB for downstream transmission.  $C/N$  is the carrier-to-noise ratio relevant for the demodulation process (Nyquist bandwidth for white noise).
+
+#### A.5.2.2 Forward Interaction path (downstream IB)
+
+The IB Forward Interaction Path must use a MPEG-2 TS stream with a modulated QAM channel as defined by ETS 300 429. Frequency range, channel spacing, and other lower physical layer parameters should follow that specification.
+
+#### A.5.2.3 Return Interaction path (upstream)
+
+##### A.5.2.3.1 Frequency range (upstream)
+
+The frequency range is not specified as mandatory although a guideline is provided to use the 5-65 MHz. Frequency stability shall be in the range  $\pm 50$  ppm measured at the upper limit of the frequency range.
+
+##### A.5.2.3.2 Modulation and mapping (upstream)
+
+The unique word (CC CC CC 0D, see A.5.3 for upstream framing) is not differentially encoded, the outputs I, Q map to the phase states as in Figure A.13.
+
+![Figure A.13/J.112 – Mapping for the QPSK constellation (upstream). The diagram shows a QPSK constellation in the I-Q plane. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'. Four points are plotted: '01' in the top-left quadrant, '11' in the top-right quadrant, '00' in the bottom-left quadrant, and '10' in the bottom-right quadrant. The text 'T0904460-97/d012' is at the bottom right.](e75b47d0ac4bd181879bc6abdf215d33_img.jpg)
+
+Figure A.13/J.112 – Mapping for the QPSK constellation (upstream). The diagram shows a QPSK constellation in the I-Q plane. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'. Four points are plotted: '01' in the top-left quadrant, '11' in the top-right quadrant, '00' in the bottom-left quadrant, and '10' in the bottom-right quadrant. The text 'T0904460-97/d012' is at the bottom right.
+
+Figure A.13/J.112 – Mapping for the QPSK constellation (upstream)
+
+For the remainder of the packet, the differential encoder shall accept bits A, B in sequence, and generate phase changes as indicated in Table A.3. It starts with the first information dibit and is initialized with the last dibit of the unique word, i.e. (A, B = 0, 1) since conversion is made MSB first.
+
+Table A.3/J.112 – Phase changes corresponding to bits A, B
+
+| A | B | Phase change |
+|---|---|--------------|
+| 0 | 0 | None         |
+| 0 | 1 | +90°         |
+| 1 | 1 | 180°         |
+| 1 | 0 | -90°         |
+
+Phase changes correspond to the following formulas (assuming I and Q are mapped to the constellation as for the unique word):
+
+$$\begin{cases} A_k = \overline{(I_{k-1} \oplus Q_{k-1})} \times (Q_{k-1} \oplus Q_k) + \overline{(I_k \oplus Q_{k-1})} \times (I_k \oplus I_{k-1}) \\ B_k = (I_{k-1} \oplus Q_{k-1}) \times (I_{k-1} \oplus I_k) + \overline{(I_{k-1} \oplus Q_k)} \times (Q_k \oplus Q_{k-1}) \end{cases}$$
+
+where  $k$  is the time index.
+
+I/Q amplitude imbalance shall be less than 1.0 dB, and phase imbalance less than 2.0°.
+
+##### A.5.2.3.3 Shaping filter (upstream)
+
+The time-domain response of a square-root raised-cosine pulse with excess bandwidth parameter  $\alpha$  is given by:
+
+$$g(t) = \frac{\sin\left[\frac{\pi t}{T}(1-\alpha)\right] + \frac{4\alpha t}{T} \cos\left[\frac{\pi t}{T}(1+\alpha)\right]}{\frac{\pi t}{T} \left[1 - \left(\frac{4\alpha t}{T}\right)^2\right]}$$
+
+where  $T$  is the symbol period.
+
+The output signal shall be defined as:
+
+$$S(t) = \sum_n [I_n \times g(t - nT) \times \cos(2\pi f_c t) - Q_n \times g(t - nT) \times \sin(2\pi f_c t)]$$
+
+with  $I_n$  and  $Q_n$  equal to  $\pm 1$ , independently from each other, and  $f_c$  the QPSK modulator's carrier frequency.
+
+The QPSK modulator divides the incoming bit stream so that bits are sent alternately to the in-phase modulator I and the out-of-phase modulator Q. These same bit streams appear at the output of the respective phase detectors in the demodulator where they are interleaved back into a serial bit stream.
+
+The QPSK signal parameters are:
+
+- RF bandwidth:  $BW = (f_b/2) * (1 + \alpha)$ ;
+- Occupied RF Spectrum:  $[f_c - BW/2, f_c + BW/2]$ ;
+- Symbol Rate:  $f_s = f_b/2$ ;
+- Nyquist Frequency:  $f_N = f_s/2$ ;
+
+with  $f_b$  = bit rate,  $f_c$  = carrier frequency and  $\alpha$  = excess bandwidth.
+
+For all three bit rates: 256 kbit/s (Grade A), 1.544 Mbit/s (Grade B) and 3.088 Mbit/s (Grade C), the Power Spectrum at the QPSK transmitter shall comply to the Power Spectrum Mask given in Table A.4 and Figure A.14. The Power Spectrum Mask shall be applied symmetrically around the carrier frequency.
+
+The specifications which shall apply to QPSK modulation for the upstream channel are given in Table A.4.
+
+**Table A.4/J.112 – QPSK upstream transmitter Power Spectrum**
+
+| $ f - f_c /f_N$   | Power Spectrum   |
+|-------------------|------------------|
+| $\leq 1 - \alpha$ | $0 \pm 0.25$ dB  |
+| at 1              | $-3 \pm 0.25$ dB |
+| at $1 + \alpha$   | $\leq -21$ dB    |
+| $\geq 2$          | $\leq -40$ dB    |
+
+![Figure A.14/J.112 – QPSK upstream transmitter Power Spectrum. The graph shows the power spectral density H(f) versus normalized frequency |f - fc| / fN. The y-axis is in dB, ranging from -40 dB to 0 dB. The x-axis has markers at 1 - alpha, 1, 1 + alpha, and 2. The spectrum is flat at 0 dB from 0 to 1 - alpha. Between 1 - alpha and 1, there is an in-band ripple rm. Between 1 and 1 + alpha, there is a Nyquist ripple rN. At f = 2, there is a sharp drop to -40 dB, labeled as out-of-band rejection > 40 dB. Text labels indicate In-band ripple rm < 0.5 dB and Nyquist ripple rN < 0.5 dB. The code T0904470-97/d013 is at the bottom right.](24b549c0c4b79c515b244625cf4f4978_img.jpg)
+
+Figure A.14/J.112 – QPSK upstream transmitter Power Spectrum. The graph shows the power spectral density H(f) versus normalized frequency |f - fc| / fN. The y-axis is in dB, ranging from -40 dB to 0 dB. The x-axis has markers at 1 - alpha, 1, 1 + alpha, and 2. The spectrum is flat at 0 dB from 0 to 1 - alpha. Between 1 - alpha and 1, there is an in-band ripple rm. Between 1 and 1 + alpha, there is a Nyquist ripple rN. At f = 2, there is a sharp drop to -40 dB, labeled as out-of-band rejection > 40 dB. Text labels indicate In-band ripple rm < 0.5 dB and Nyquist ripple rN < 0.5 dB. The code T0904470-97/d013 is at the bottom right.
+
+Figure A.14/J.112 – QPSK upstream transmitter Power Spectrum
+
+##### A.5.2.3.4 Randomizer (upstream)
+
+The unique word shall be sent in clear (see A.5.3). After addition of the FEC bytes, randomization shall apply only to the payload area and FEC bytes, with the randomizer performing modulo -2 addition of the data with a pseudo-random sequence. The generating polynomial is  $x^6 + x^5 + 1$  with seed all ones. We assume the first value coming out of the pseudo-random generator taken into account is 0. Byte/serial conversion shall be MSB first. The binary sequence generated by the shift register starts with 00000100... The first "0" is to be added in the first bit after the unique word.
+
+A complementary non self-synchronizing de-randomizer is used in the receiver to recover the data. The de-randomizer shall be enabled after detection of the unique word.
+
+![Figure A.15/J.112 – Randomizer. This is a block diagram of a randomizer. Serial input enters a circular adder (+). The output of this adder goes into a series of six square blocks representing a shift register. The output of the shift register is fed into another circular adder (+). The output of this second adder is the Serial output. A feedback loop connects the output of the second adder back to its input. The code T0904480-97/d014 is at the bottom right.](0ee9d674085524d589646a6c3fb21ec3_img.jpg)
+
+Figure A.15/J.112 – Randomizer. This is a block diagram of a randomizer. Serial input enters a circular adder (+). The output of this adder goes into a series of six square blocks representing a shift register. The output of the shift register is fed into another circular adder (+). The output of this second adder is the Serial output. A feedback loop connects the output of the second adder back to its input. The code T0904480-97/d014 is at the bottom right.
+
+Figure A.15/J.112 – Randomizer
+
+##### A.5.2.3.5 Bit rate (upstream)
+
+Three grades of modulation transmission rate are specified:
+
+Table A.5/J.112 – Upstream bit-rates for modulation grades A, B and C
+
+| Grade | Rate         |
+|-------|--------------|
+| A     | 256 kbit/s   |
+| B     | 1.544 Mbit/s |
+| C     | 3.088 Mbit/s |
+
+A QPSK modulator (NIU transmitter) may support A, B and C grades of transmission rate. (Only the implementation of one of these grades should be mandatory.) A QPSK demodulator (INA receiver) shall support at least one grade A, B or C, but may support all grades.
+
+Symbol rate accuracy should be within ± 50 ppm.
+
+For grade A, the rate is 500 slots/s. For grade B, the rate is 3000 slots/s. For grade C, the rate is 6000 slots/s.
+
+##### A.5.2.3.6 Transmit power level (upstream)
+
+At the output, the transmit power level shall be in the range 85-113 dBµV (RMS) (75 Ω). In some geographic areas, it may be necessary to cover the range 85-122 dBµV (RMS) (75 Ω). However, note that high power may lead to electromagnetic compatibility problems. This power shall be adjusted by steps of 0.5 dB by MAC messages coming from the INA.
+
+##### A.5.2.3.7 Carrier suppression when idle (upstream)
+
+The Carrier Suppression shall be more than 60 dB below nominal power output level, over the entire power output range. A terminal is considered to be idle if it is 3 slots before an imminent transmission or 3 slots after its most recent transmission.
+
+##### A.5.2.3.8 Summary (upstream)
+
+See Table A.6.
+
+**Table A.6/J.112 – Summary (upstream)**
+
+| Transmission Rate     | <p>Three grades of modulation transmission rate are specified:</p> <table style="border: none; width: 50%;"> <thead> <tr> <th style="text-align: left; text-decoration: underline;">Grade</th> <th style="text-align: left; text-decoration: underline;">Rate</th> </tr> </thead> <tbody> <tr> <td>A</td> <td>256 kbit/s</td> </tr> <tr> <td>B</td> <td>1.544 Mbit/s</td> </tr> <tr> <td>C</td> <td>3.088 Mbit/s</td> </tr> </tbody> </table> <p>A QPSK modulator (transmitter) may support A, B and C grades of transmission rate. (Only the implementation of one of these grades should be mandatory.) A QPSK demodulator (receiver) shall support at least one grade A, B, or C, but may support all grades.</p> | Grade        | Rate | A            | 256 kbit/s | B | 1.544 Mbit/s | C | 3.088 Mbit/s |      |   |   |      |   |   |      |
+|-----------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------|------|--------------|------------|---|--------------|---|--------------|------|---|---|------|---|---|------|
+| Grade                 | Rate                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |              |      |              |            |   |              |   |              |      |   |   |      |   |   |      |
+| A                     | 256 kbit/s                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |              |      |              |            |   |              |   |              |      |   |   |      |   |   |      |
+| B                     | 1.544 Mbit/s                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |              |      |              |            |   |              |   |              |      |   |   |      |   |   |      |
+| C                     | 3.088 Mbit/s                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |              |      |              |            |   |              |   |              |      |   |   |      |   |   |      |
+| Modulation            | Differentially encoded QPSK                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |              |      |              |            |   |              |   |              |      |   |   |      |   |   |      |
+| Transmit Filtering    | Alpha = 0.30 square root raised cosine                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |              |      |              |            |   |              |   |              |      |   |   |      |   |   |      |
+| Channel Spacing       | <p>200 kHz for Grade A (256 kbit/s)</p> <p>1 MHz for Grade B (1.544 Mbit/s)</p> <p>2 MHz for Grade C (3.088 Mbit/s)</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |              |      |              |            |   |              |   |              |      |   |   |      |   |   |      |
+| Frequency Step Size   | 50 kHz                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |              |      |              |            |   |              |   |              |      |   |   |      |   |   |      |
+| Randomization         | <p>The unique word shall be sent in the clear. After addition of the FEC bytes, randomization shall apply only to the payload area and FEC bytes, with the randomizer performing modulo –2 addition of the data with a pseudo-random sequence. The generating polynomial is <math>x^6 + x^5 + 1</math> with seed all ones.</p> <p>Byte/serial conversion shall be MSB first.</p> <p>A complementary non self-synchronizing de-randomizer is used in the receiver to recover the data. The de-randomizer shall be enabled after detection of the unique word.</p>                                                                                                                                                     |              |      |              |            |   |              |   |              |      |   |   |      |   |   |      |
+| Differential Encoding | <p>The differential encoder shall accept bits A, B in sequence, and generate phase changes as follows. In serial mode, A arrives first.</p> <table style="border: none; width: 50%;"> <thead> <tr> <th style="text-align: left; text-decoration: underline;">A</th> <th style="text-align: left; text-decoration: underline;">B</th> <th style="text-align: left; text-decoration: underline;">Phase Change</th> </tr> </thead> <tbody> <tr> <td>0</td> <td>0</td> <td>None</td> </tr> <tr> <td>0</td> <td>1</td> <td>+90°</td> </tr> <tr> <td>1</td> <td>1</td> <td>180°</td> </tr> <tr> <td>1</td> <td>0</td> <td>–90°</td> </tr> </tbody> </table>                                                                | A            | B    | Phase Change | 0          | 0 | None         | 0 | 1            | +90° | 1 | 1 | 180° | 1 | 0 | –90° |
+| A                     | B                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | Phase Change |      |              |            |   |              |   |              |      |   |   |      |   |   |      |
+| 0                     | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | None         |      |              |            |   |              |   |              |      |   |   |      |   |   |      |
+| 0                     | 1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | +90°         |      |              |            |   |              |   |              |      |   |   |      |   |   |      |
+| 1                     | 1                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | 180°         |      |              |            |   |              |   |              |      |   |   |      |   |   |      |
+| 1                     | 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | –90°         |      |              |            |   |              |   |              |      |   |   |      |   |   |      |
+
+**Table A.6/J.112 – Summary (upstream) (*concluded*)**
+
+|                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
+|-----------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| <p>Signal Constellation</p> <p>NOTE – The unique word (0x CC CC CC 0D) does not go through differential encoding.</p> | <p>The outputs I, Q from the differential encoder map to the phase states as in Figure A.16.</p> <div style="text-align: center;"> <img alt="Figure A.16/J.112: QPSK Signal Constellation diagram. It shows four points in a 2D plane defined by I (horizontal) and Q (vertical) axes. The points are labeled: top-left '01', top-right '11', bottom-left '00', and bottom-right '10'. The diagram is labeled T0904490-97/d015." data-bbox="826 309 1109 593" src="82828d3c49d0c1171ef6712df66ece08_img.jpg"/> <p><b>Figure A.16/J.112</b></p> </div>                                                                                                                                                                                                                                                                                                                       |
+| <p>Frequency Range</p>                                                                                                | <p>5-65 MHz recommended but not mandatory</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
+| <p>Frequency Stability</p>                                                                                            | <p>± 50 ppm measured at the upper limit of the frequency range</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
+| <p>Symbol Rate Accuracy</p>                                                                                           | <p>± 50 ppm</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
+| <p>Transmit Spectral Mask</p>                                                                                         | <p>A common mask for all three bit rates: 256 kbit/s (Grade A), 1.544 Mbit/s (Grade B) and 3.088 Mbit/s (Grade C) is given in Table A.4 and Figure A.14.</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
+| <p>Carrier Suppression when Transmitter Active</p>                                                                    | <p>&gt; 30 dB</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
+| <p>Carrier Suppression when Transmitter Idle</p>                                                                      | <p>The Carrier Suppression shall be more than 60 dB below nominal power output level over the entire power output range (see Recommendation I.361 for details) and 30 dB right after or before transmission.</p> <p>Idle Transmitter Definition: a terminal is considered to be idle if it is 3 slots before an imminent transmission or 3 slots after its most recent transmission.</p> <div style="text-align: center;"> <img alt="Diagram showing carrier suppression levels relative to a burst packet. The central 'Burst packet' is 63 bytes long with 1 byte guard bands on either side. Immediately before and after the guard bands, the suppression is 30 dB. Beyond 3 slots from the burst, the suppression increases to 60 dB. The diagram is labeled T0904500-97/d016." data-bbox="542 1209 1388 1534" src="43fed1059c7f314ba5b8e5584b33c3b3_img.jpg"/> </div> |
+| <p>I/Q Amplitude Imbalance</p>                                                                                        | <p>&lt; 1.0 dB</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
+| <p>I/Q Phase Imbalance</p>                                                                                            | <p>&lt; 2.0°</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
+| <p>Transmit Power Level at the modulator output (upstream)</p>                                                        | <p>85-113 dBμV (RMS) (75 Ω). In some geographic areas, it may be necessary to cover the range 85-122 dBμV (RMS) (75 Ω).</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
+
+##### A.5.2.3.9 Packet loss upstream (informative)
+
+Packet loss at the INA shall be less than  $10^{-6}$  at C/N > 20 dB (after error correction) for upstream transmission.
+
+NOTE – A packet loss occurs when one or more bit per packet (after error correction) are uncorrectable. The C/N is referred at the demodulator input (Nyquist bandwidth, white noise).
+
+### A.5.3 Framing
+
+#### A.5.3.1 Forward interaction path (downstream OOB)
+
+##### A.5.3.1.1 Signalling Link Extended Superframe Framing format
+
+The Signalling Link Extended Superframe (SL-ESF) frame structure is shown in Figure A.17. The bitstream is partitioned into 4632-bit Extended Superframes. Each Extended Superframe consists of 24 × 193-bit frames. Each frame consists of 1 Overhead (OH) bit and 24 bytes (192 bits) of payload.
+
+![Diagram of SL-ESF frame structure showing 24 frames, each with 193 bits (1 OH + 192 Payload).](04cfca33e3fc26513abe649d7474f733_img.jpg)
+
+The diagram illustrates the SL-ESF frame structure. At the top, a horizontal row of 24 boxes is labeled 1 through 24. Below this row, a double-headed arrow spans the entire width and is labeled "24 frames". A diagonal line descends from the left side of this row to a larger diagram below. Along this diagonal line, the text "24 frames × 193 bits = 4632 bits" is written. The bottom diagram shows a single frame structure. It consists of two rows. The top row has two cells: the first is labeled "OH" and the second is labeled "Payload". The bottom row has two cells: the first contains the number "1", and the second contains the text "192 bits". A double-headed arrow spans the width of the "Payload" and "192 bits" cells. In the bottom right corner of the diagram, the text "T0904510-97/d017" is present.
+
+Diagram of SL-ESF frame structure showing 24 frames, each with 193 bits (1 OH + 192 Payload).
+
+Figure A.17/J.112 – SL-ESF frame structure
+
+##### A.5.3.1.2 Frame overhead
+
+There are 24 frame overhead bits in the Extended Superframe which are divided into Extended Superframe Frame Alignment Signal (F1-F6), Cyclic Redundancy Check (C1-C6), and M-bit Data Link (M1-M12) as shown in Table A.7. Bit number 0 is received first.
+
+###### ESF Frame Alignment Signal
+
+The ESF Frame Alignment Signal (FAS) is used to locate all 24 frames and overhead bit positions. The bit values of the FAS are defined as follows:
+
+$$F1 = 0, F2 = 0, F3 = 1, F4 = 0, F5 = 1, F6 = 1$$
+
+###### ESF Cyclic Redundancy Check
+
+The Cyclic Redundancy Check field contains the CRC-6 check bits calculated over the previous Extended Superframe (CRC Message block [CMB] size = 4632 bits). Before calculation, all 24 frame overhead bits are equal to "1". All information in the other bit positions is unchanged. The check bit sequence C1-C6 is the remainder after multiplication by  $x^6$  and then division by the generator polynomial  $x^6 + x + 1$  of the CMB. C1 is the most significant bit of the remainder. The initial remainder value is preset to all zeros.
+
+###### ESF Mbit data link
+
+The M-bits in the SL-ESF serve for slot timing assignment (see A.5.4).
+
+**Table A.7/J.112 – Frame overhead**
+
+| Frame Number                                                                                            | Bit Number | Overhead bit | Data (192 bits) |
+|---------------------------------------------------------------------------------------------------------|------------|--------------|-----------------|
+| 1                                                                                                       | 0          | <b>M1</b>    |                 |
+| 2                                                                                                       | 193        | C1           |                 |
+| 3                                                                                                       | 386        | <b>M2</b>    |                 |
+| 4                                                                                                       | 579        | F1 = 0       |                 |
+| 5                                                                                                       | 772        | <b>M3</b>    |                 |
+| 6                                                                                                       | 965        | C2           |                 |
+| 7                                                                                                       | 1158       | <b>M4</b>    |                 |
+| 8                                                                                                       | 1351       | F2 = 0       |                 |
+| 9                                                                                                       | 1544       | <b>M5</b>    |                 |
+| 10                                                                                                      | 1737       | C3           |                 |
+| 11                                                                                                      | 1930       | <b>M6</b>    |                 |
+| 12                                                                                                      | 2123       | F3 = 1       |                 |
+| 13                                                                                                      | 2316       | <b>M7</b>    |                 |
+| 14                                                                                                      | 2509       | C4           |                 |
+| 15                                                                                                      | 2702       | <b>M8</b>    |                 |
+| 16                                                                                                      | 2895       | F4 = 0       |                 |
+| 17                                                                                                      | 3088       | <b>M9</b>    |                 |
+| 18                                                                                                      | 3281       | C5           |                 |
+| 19                                                                                                      | 3474       | <b>M10</b>   |                 |
+| 20                                                                                                      | 3667       | F5 = 1       |                 |
+| 21                                                                                                      | 3860       | <b>M11</b>   |                 |
+| 22                                                                                                      | 4053       | C6           |                 |
+| 23                                                                                                      | 4246       | <b>M12</b>   |                 |
+| 24                                                                                                      | 4439       | F6 = 1       |                 |
+| FAS Frame Alignment Signal (F1-F6)<br>DL Mbit Data Link (M1-M12)<br>CRC Cyclic Redundancy Check (C1-C6) |            |              |                 |
+
+##### A.5.3.1.3 Payload structure
+
+The SL-ESF frame payload structure provides a known container for defining the location of the ATM cells and the corresponding Reed-Solomon parity values. The SL-ESF payload structure is shown in Table A.8.
+
+The SL-ESF payload structure consists of 5 rows of 57 bytes each, 4 rows of 58 bytes each which includes 1 byte trailer, and 1 row of 59 bytes, which includes a 2-byte trailer. The first bit of the SL-ESF payload structure follows the M1 bit of the SL-ESF frame. The SL-ESF payload fields are defined as follows. Table A.8 is read from left to right and top to bottom and mapped as is into the ESF frame described by Table A.7.
+
+**Table A.8/J.112 – ESF payload structure**
+
+|    | ← 2 → |     | ← 53 →   |  |  |  |  |  | ← 2 →     |         |
+|----|-------|-----|----------|--|--|--|--|--|-----------|---------|
+| 1  | R1a   | R1b | ATM cell |  |  |  |  |  | RS parity |         |
+| 2  | R1c   | R2a |          |  |  |  |  |  |           | R2<br>b |
+| 3  | R2c   | R3a |          |  |  |  |  |  |           |         |
+| 4  | R3b   | R3c |          |  |  |  |  |  |           | R4<br>a |
+| 5  | R4b   | R4c |          |  |  |  |  |  |           |         |
+| 6  | R5a   | R5b |          |  |  |  |  |  |           | R5<br>c |
+| 7  | R6a   | R6b |          |  |  |  |  |  |           |         |
+| 8  | R6c   | R7a |          |  |  |  |  |  |           | R7<br>b |
+| 9  | R7c   | R8a |          |  |  |  |  |  |           |         |
+| 10 | R8b   | R8c |          |  |  |  |  |  |           | T T     |
+
+T0904520-97/d018
+
+###### **ATM cell structure**
+
+The format for each ATM cell structure is shown in Figure A.18. This structure and field coding shall be consistent with the structure and coding given in Recommendation I.361 for ATM UNI.
+
+![Diagram of ATM cell format showing Header (40 bits), Information Payload (384 bits), and total size (53 bytes).](0b3d9fe35da3ee0c88f1420bb9ed7a03_img.jpg)
+
+The diagram illustrates the structure of an ATM cell. It is divided into two main parts: a 'Header' and an 'Information Payload'. The Header is 40 bits long, and the Information Payload is 384 bits long. The total length of the cell is 53 bytes. The diagram shows a horizontal line representing the cell, with a vertical line separating the Header and the Information Payload. The Header is on the left, and the Information Payload is on the right. The total length is indicated by a double-headed arrow at the bottom, labeled '53 bytes'.
+
+Diagram of ATM cell format showing Header (40 bits), Information Payload (384 bits), and total size (53 bytes).
+
+T0904530-97/d019
+
+**Figure A.18/J.112 – ATM cell format**
+
+###### **Channel coding and interleaving**
+
+Reed-Solomon encoding with  $t = 1$  shall be performed on each ATM cell. This means that 1 erroneous byte per ATM cell can be corrected. This process adds 2 parity bytes to the ATM cell to give a codeword of (55,53).
+
+The Reed-Solomon code shall have the following generator polynomials:
+
+- Code Generator Polynomial:  $g(x) = (x + \mu^0)(x + \mu^1)$ , where  $\mu = 02$  hex;
+- Field Generator Polynomial:  $p(x) = x^8 + x^4 + x^3 + x^2 + 1$ .
+
+The shortened Reed-Solomon code shall be implemented by appending 200 bytes, all set to zero, before the information bytes at the input of a (255,253) encoder; after the coding procedure these bytes are discarded.
+
+Convolutional interleaving shall be applied to the ATM cells contained in the SL-ESF. The Rxa-Rxc bytes and the two T bytes shall not be included in the interleaving process. Convolutional interleaving is applied by interleaving 5 lines of 55 bytes.
+
+Following the scheme of Figure A.19, convolutional interleaving shall be applied to the error protected packets. The convolutional interleaving process shall be based on the Forney approach, which is compatible with the Ramsey type III approach, with  $I = 5$ . The Interleaved frame shall be composed of overlapping error protected packets and a group of 10 packets shall be delimited by the start of the SL-ESF.
+
+![Diagram of Interleaver and de-interleaver structures. The diagram shows an input (IN) entering a central 'CHANNEL' block. Inside the block, there are five branches labeled 0 to 4. Branch 0 contains one cell with '0'. Branch 1 contains one cell with 'M'. Branch 2 contains two cells with 'M'. Branch 3 contains three cells with 'M'. Branch 4 contains four cells with 'M'. On the output side, the branches are reversed: Branch 0 contains four cells with 'M', Branch 1 contains three cells with 'M', Branch 2 contains two cells with 'M', Branch 3 contains one cell with 'M', and Branch 4 contains one cell with '0'. The output is labeled 'OUT'. A reference code 'T0904540-97/d020' is at the bottom right.](70a863dc6cd47bac82c12162a9479aac_img.jpg)
+
+Diagram of Interleaver and de-interleaver structures. The diagram shows an input (IN) entering a central 'CHANNEL' block. Inside the block, there are five branches labeled 0 to 4. Branch 0 contains one cell with '0'. Branch 1 contains one cell with 'M'. Branch 2 contains two cells with 'M'. Branch 3 contains three cells with 'M'. Branch 4 contains four cells with 'M'. On the output side, the branches are reversed: Branch 0 contains four cells with 'M', Branch 1 contains three cells with 'M', Branch 2 contains two cells with 'M', Branch 3 contains one cell with 'M', and Branch 4 contains one cell with '0'. The output is labeled 'OUT'. A reference code 'T0904540-97/d020' is at the bottom right.
+
+Figure A.19/J.112 – Interleaver and de-interleaver structures
+
+The interleaver is composed of  $I$  branches, cyclically connected to the input byte-stream by the input switch. Each branch shall be a First In First Out (FIFO) shift register, with depth ( $M_j$ ) cells (where  $M = N/I$ ,  $N = 55$  = error protected frame length,  $I$  = interleaving depth,  $j$  = branch index). The input and output switches shall be synchronized. Each cell of the FIFO shall contain one byte.
+
+For synchronization purposes, the first byte of each error protected packet shall be always routed into the branch "0" of the interleaver (corresponding to a null delay). The third byte of the SL-ESF payload (the byte immediately following R1b) shall be aligned to the first byte of an error protected packet.
+
+The de-interleaver is similar, in principle, to the interleaver, but the branch indexes are reversed (i.e. branch 0 corresponds to the largest delay). The de-interleaver synchronization is achieved by routing the third data byte of the SL-ESF into the "0" branch.
+
+###### Reception indicator fields and slot boundary fields
+
+A downstream channel contains control information for each of its associated upstream channels. This information is contained within structures known as MAC Flags. A set of MAC Flags, represented by either 24 bits (denoted  $b_0 \dots b_{23}$ ) or by 3 bytes (denoted  $R_{xa}$ ,  $R_{xb}$  and  $R_{xc}$ ), are uniquely assigned to a given upstream channel "x":
+
+- $R_{xa} = \text{EE}(b_0 \dots b_7) = (\text{msb} \dots \text{lsb});$
+- $R_{xb} = \text{EE}(b_8 \dots b_{15}) = (\text{msb} \dots \text{lsb});$
+- $R_{xc} = \text{EE}(b_{16} \dots b_{23}) = (\text{msb} \dots \text{lsb}).$
+
+These flags constitute the slot configuration information for the upstream channel "x" where "x" is indicated to the NIU in the «MAC Flag sets» given in MAC messages (Default Configuration message, Connect message, Reprovision message, Transmission Control message) and is described as follows:
+
+The  $MAC\_Flag\_Set$  is a 5-bit field indicating the MAC Flag set number assigned to the channel (i.e.  $R_{1a}$ ,  $R_{1b}$  and  $R_{1c}$  represent MAC Flag set 1). It can take the values 1..16. Values 0 and 17..31 are invalid.
+
+In the OOB downstream case, each SL-ESF frame structure contains eight sets of MAC Flags represented by Rxa, Rxb and Rxc, where x is replaced by the numbers 1..8. In the case of a 1.544 Mbit/s downstream bit rate, only one SL-ESF frame occurs during a 3 ms interval providing 8 sets of MAC Flags. In the case of a 3.088 Mbit/s downstream bit rate, two SL-ESF frames A and B occur during a 3-ms interval, providing 16 sets of MAC Flags. The second set of MAC Flags (contained in the second SL-ESF) are denoted by Rxa, Rxb and Rxc, where x is replaced by the numbers 9 through 16.
+
+In the IB downstream case, the MAC Flags are contained in the MAC Control message structure which can contain as many as 16 MAC Flag sets. The MAC Flags 1-8 are contained in the "MAC Flags" field and the MAC Flags 9-16 are contained in the "Extension Flags" field.
+
+In case of a 3.088 Mbit/s upstream channel, two sets of MAC Flags are required. In this case, the MAC\_Flag\_Set parameter represents the first of two successively assigned MAC Flag sets (Rxa-Rxc, Rya-Ryc with  $y = x + 1 \bmod 8$  (for 1.544 Mbit/s DS) or  $y = x + 1 \bmod 16$  (for 3.088 Mbit/s DS)). In particular, if one downstream OOB 1.544 Mbit/s channel controls 3.088 Mbit/s upstream channels, at most 4 upstream channels can be controlled, due to the number of available MAC Flags.
+
+The bits b0 to b23 are defined as follows:
+
+- b0 = ranging slot indicator for next 3 ms period (msb)
+- b1-b6 = slot boundary definition field for next 3 ms period
+- b7 = slot 1 reception indicator (as shown in Table A.12)
+- b8 = slot 2 reception indicator (as shown in Table A.12)
+- b9 = slot 3 reception indicator (as shown in Table A.12)
+- b10 = slot 4 reception indicator (as shown in Table A.12)
+- b11 = slot 5 reception indicator (as shown in Table A.12)
+- b12 = slot 6 reception indicator (as shown in Table A.12)
+- b13 = slot 7 reception indicator (as shown in Table A.12)
+- b14 = slot 8 reception indicator (as shown in Table A.12)
+- b15 = slot 9 reception indicator (as shown in Table A.12)
+- b16-b17 = reservation control for next 3 ms period
+- b18-b23 = CRC-6 parity (see definition in SL-ESF section)
+
+When the upstream data rate is 256 kbit/s, then only the first three slot reception indicators are valid. When the upstream data rate is 1.544 Mbit/s, then the 9 slots are valid. When the upstream data rate is 3.088 Mbit/s, the 9 slots of this field and the 9 slots of the following field are valid: two consecutive Slot Configuration fields are then used. The definition of the first Slot Configuration field is unchanged. The definition of the second Slot Configuration field extends the boundary definition to cover upstream slots 10 through 18, and the reception indicators to cover upstream slots 10 through 18.
+
+In general, when the upstream rate is lower than the downstream rate, there are several OOB downstream superframes during groups of  $k$  upstream slots (where  $k = 3$  for 256 kbit/s upstream,  $k = 9$  for 1.544 Mbit/s upstream). In that case, configuration slots remain equal over all superframes corresponding to one group of  $k$  upstream slots.
+
+**Ranging slot indicator (b0):** When this bit is active ( $b0 = 1$ ), the first three slots of upstream channel "x" which correspond to the occurrence of the next superframe of the related downstream channel are designated as ranging slots. A ranging message may be transmitted in the second ranging slot "on contention", and the first and third ranging slots may not be used for transmission (guard band for ranging operations).
+
+**Slot Boundary Definition field (b1-b6):** Slot types are assigned to upstream slots using bits b0-b6. The slots are grouped into regions among "spans" of 3 slots (256 kbit/s), 9 slots (1.544 Mbit/s), or 18 slots (3.088 Mbit/s), such that slots of a similar type are contained within the same region. The order of the regions is Ranging slot, Contention based slots, Reserved slots and Fixed rate based slots. If a ranging slot is available within a "span", it will consist of the first three slot times in the "span", assuming b1-b6 are not in the range 55-63 (see Table A.9). A ranging slot is indicated by b0 = 1. The boundaries between the remaining regions of the "spans" are defined by b1-b6. The boundaries are defined as shown in Table A.9.
+
+**Table A.9/J.112 – Slot Boundary Definition field (b1-b6)**
+
+|            |        |
+|------------|--------|
+| Boundary 0 |        |
+| Boundary 1 | Slot 1 |
+| Boundary 2 | Slot 2 |
+| Boundary 3 | Slot 3 |
+| Boundary 4 | Slot 4 |
+| Boundary 5 | Slot 5 |
+| Boundary 6 | Slot 6 |
+| Boundary 7 | Slot 7 |
+| Boundary 8 | Slot 8 |
+| Boundary 9 | Slot 9 |
+
+The boundary positions are defined by b1-b6 as shown in Table A.10.
+
+**Table A.10/J.112 – Boundary positions (b1-b6)**
+
+| (Note 1)<br>(Note 2) | 0 | 1  | 2  | 3  | 4  | 5  | 6  | 7  | 8  | 9  |
+|----------------------|---|----|----|----|----|----|----|----|----|----|
+| 0 (Note 3)           | 0 | 1  | 2  | 3  | 4  | 5  | 6  | 7  | 8  | 9  |
+| 1 (Note 3)           |   | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 |
+| 2 (Note 3)           |   |    | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 |
+| 3                    |   |    |    | 27 | 28 | 29 | 30 | 31 | 32 | 33 |
+| 4                    |   |    |    |    | 34 | 35 | 36 | 37 | 38 | 39 |
+| 5                    |   |    |    |    |    | 40 | 41 | 42 | 43 | 44 |
+| 6                    |   |    |    |    |    |    | 45 | 46 | 47 | 48 |
+| 7                    |   |    |    |    |    |    |    | 49 | 50 | 51 |
+| 8                    |   |    |    |    |    |    |    |    | 52 | 53 |
+| 9                    |   |    |    |    |    |    |    |    |    | 54 |
+
+Example: b0 = 0, b1-b6 = 22: Contention (1-2), reserved (3-5), Fixed rate (6-9).  
+NOTE 1 – Row = Contention based / Reserved region boundary.  
+NOTE 2 – Column = Reserved packet / Fixed rate based region boundary.  
+NOTE 3 – When the ranging control slot indicator (b0) is set to "1", the values in rows 0-2 are illegal values, and values in row 3 means that there are no contention slots, because slots 1-3 are defined as ranging control slots.
+
+The remaining values of the Slot Boundary Definition field are provided in Table A.11.
+
+**Table A.11/J.112 – Slot Boundary Definition field**
+
+| b1-b6 value | Ranging control slots | Contention slots | Reservation slots | Fixed rate slots |
+|-------------|-----------------------|------------------|-------------------|------------------|
+| 55          | 1-6                   | 7-9              | –                 | –                |
+| 56          | 1-6                   | 7-8              | –                 | 9                |
+| 57          | 1-6                   | 7                | 8-9               | –                |
+| 58          | 1-6                   | 7                | 8                 | 9                |
+| 59          | 1-6                   | 7                | –                 | 8-9              |
+| 60          | 1-6                   | –                | 7-8               | 9                |
+| 61          | 1-6                   | –                | 7                 | 8-9              |
+| 62          | 1-6                   | –                | –                 | 7-9              |
+| 63          | 1-9                   | –                | –                 | –                |
+
+NOTE 1 – For b1-b6 = 55-63, b0 must be set to 1. Note that for b1-b6 between 55 and 62, two ranging slots are provided (2 and 5). For b1-b6 = 63, three ranging slots are provided (2, 5, and 8).
+
+The values in the above tables are derived from b1-b6 in the following manner:
+
+$$b1 + (b2 \times 2) + (b3 \times 4) + (b4 \times 8) + (b5 \times 16) + (b6 \times 32)$$
+
+**Warning:** This formula indicates that b6 is considered as msb of b1-b6 word, whereas b0 is msb of the entire word b0-b23. Although this "looks" inconsistent, it has not been changed for the purpose of compatibility with the DAVIC standard.
+
+When the upstream data channel is a 256 kbit/s data channel, then only the first four rows and columns of Table A.10 are valid, and Table A.11 is not valid.
+
+NOTE 2 – If slot boundary fields change while some NIUs have already been affected slots in the reservation slots area, these NIUs are responsible of updating the list of physical slots. Specifically, slots are assigned by MAC Reservation Grant messages, which contain a Reference slot that does not depend on the slot boundary fields and a Grant\_slot\_count which corresponds to the number of slots assigned within the reservation slots boundary field. If the field changes, the list of physical slots on which the NIU can transmit automatically changes accordingly.
+
+**Slot reception indicators (b7-b15):** When a slot reception indicator is active ("1"), this indicates that a cell was received without collision. The relationship between a given US slot and its indicator is shown in Table A.11. When the indicator is inactive ("0"), this indicates that either a collision was detected or no cell was received in the corresponding upstream slot.
+
+Slot reception indicators lead to the retransmission procedure only when contention access is used as described in A.5.5.2.4.
+
+**Reservation Control (b16-b17):** When the reservation control field has the value of 0, no reservation attempts are allowed to be transmitted on the corresponding QPSK upstream channel during the slot positions associated with the next 3 ms period. When the Reservation Control field has the value of 1, reservation attempts can be made. The values 2 and 3 are reserved. A reservation attempt corresponds to sending a MAC Reservation Request message (see MAC section). b16 is msb.
+
+**Table A.12/J.112 – Relationship of US slot to DA indicator at the INA**
+
+|                       | <b>1.544 Mbit/s downstream</b>                                                                                                                                                                                                                                                                                                |  | <b>3.088 Mbit/s downstream</b>                                                                                                                                                                                                                                                                                                          |  |
+|-----------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--|
+| 256 kbit/s upstream   | 1 frame<br><img alt="Diagram for 256 kbit/s upstream at 1.544 Mbit/s downstream. Downstream (DS) shows 6 frames, the 5th containing 'I'. Upstream (US) shows 3 slots, the 1st shaded. An arrow points from the shaded slot to the 'I' frame." data-bbox="379 286 805 504" src="e5e74a3be9619cbf5cfea6d02f3c6b9c_img.jpg"/>    |  | 1 frame<br><img alt="Diagram for 256 kbit/s upstream at 3.088 Mbit/s downstream. Downstream (DS) shows 10 frames, the 9th and 10th containing 'I'. Upstream (US) shows 3 slots, the 1st shaded. An arrow points from the shaded slot to the 'I' frames." data-bbox="922 286 1364 504" src="ad408c10a933c3252083c24300e44c5b_img.jpg"/>  |  |
+| 1.554 Mbit/s upstream | 1 frame<br><img alt="Diagram for 1.554 Mbit/s upstream at 1.544 Mbit/s downstream. Downstream (DS) shows 3 frames, the 3rd containing 'I'. Upstream (US) shows 9 slots, the 1st shaded. An arrow points from the shaded slot to the 'I' frame." data-bbox="379 533 805 750" src="4b6339d67a122af171cc676bde024524_img.jpg"/>  |  | 1 frame<br><img alt="Diagram for 1.554 Mbit/s upstream at 3.088 Mbit/s downstream. Downstream (DS) shows 6 frames, the 5th and 6th containing 'I'. Upstream (US) shows 9 slots, the 1st shaded. An arrow points from the shaded slot to the 'I' frames." data-bbox="922 533 1364 750" src="bb2c781b05b5c5a1cc3af4a47c291428_img.jpg"/>  |  |
+| 3.088 Mbit/s upstream | 1 frame<br><img alt="Diagram for 3.088 Mbit/s upstream at 1.544 Mbit/s downstream. Downstream (DS) shows 3 frames, the 3rd containing 'I'. Upstream (US) shows 18 slots, the 1st shaded. An arrow points from the shaded slot to the 'I' frame." data-bbox="379 779 805 996" src="36898f219c353af987401692f4f00e05_img.jpg"/> |  | 1 frame<br><img alt="Diagram for 3.088 Mbit/s upstream at 3.088 Mbit/s downstream. Downstream (DS) shows 6 frames, the 5th and 6th containing 'I'. Upstream (US) shows 18 slots, the 1st shaded. An arrow points from the shaded slot to the 'I' frames." data-bbox="922 779 1364 996" src="7b97f1c8a5f85a024001504ea85a4c60_img.jpg"/> |  |
+
+NOTE 1 – 'I' indicates the downstream frame(s) in which indicators (contained within the MAC Flag Sets) are sent. These indicators control the upstream slots in the shaded area.
+
+NOTE 2 – In the 3.088 downstream, two successive frames contain MAC Flag Sets 1..16. Two successive MAC Flag Sets are used to control the 18 slots of a 3.088 upstream channel.
+
+NOTE 3 – This table refers to the position of US slots with respect to the positions of DS superframes at the INA receiver. NIUs should have their Time\_Offset\_Value of transmission set such that this table applies.
+
+T0904550-97/d021
+
+**CRC-6 Parity (b18-b23):** This field contain a CRC-6 parity value calculated over the previous 18 bits. The CRC-6 parity value is described in the SL-ESF frame format section. b18 is msb.
+
+In the case where there is more than one OOB DS QPSK channel related to an upstream QPSK channel, the SL-ESF overhead bits and the payload R-bytes shall be identical in those OOB DS channels, with the exception of the overhead CRC (C1-C6) bits, which are specific to each of those OOB DS channels. Such related DS channels shall be synchronized (transmitted synchronously). This scenario applies for example when a lot more bandwidth is needed for DS information than for US information.
+
+The MAC messages that are required to perform the MAC functions for the upstream channel shall be transmitted on each of its related OOB DS channels.
+
+###### **Trailer bytes**
+
+These bytes are not used. They are equal to 0.
+
+#### A.5.3.2 Forward Interaction path (downstream IB)
+
+The structure that is utilized when the downstream QAM channel is carrying MPEG-2 TS packets is shown in Figure A.20. MSBs of each field are transmitted first.
+
+| 4           | 3               | 2           | 3                | 26        | 26         | 40          | 40          | 40          | 4               |
+|-------------|-----------------|-------------|------------------|-----------|------------|-------------|-------------|-------------|-----------------|
+| MPEG Header | Upstream Marker | Slot Number | MAC Flag Control | MAC Flags | Ext. Flags | MAC Message | MAC Message | MAC Message | Reserve field c |
+
+Figure A.20/J.112 – Frame structure (MPEG-2 TS format)
+
+where:
+
+**MPEG Header** is the 4-byte MPEG-2 Transport Stream Header as defined in ISO 13818-1 with a specific PID designated for MAC messages. This PID is to be specified by ETS 300 468, either within the PMT, PAT tables or as a default specific value (when MAC is considered as a SI section).
+
+**Upstream Marker** is a 24-bit field which provides upstream QPSK synchronization information. (As mentioned in A.5.1.4, at least one packet with synchronization information must be sent in every period of 3 ms.) The definition of the field is as follows:
+
+##### **bit 0: upstream marker enable** (msb)
+
+When this field has the value '1', the slot marker pointer is valid. When this field has the value '0', the slot marker pointer is not valid.
+
+##### **bit 1-7: reserved**
+
+##### **bit 8-23: upstream slot marker pointer (bit 23 MSB)**
+
+The slot marker pointer is a 16-bit unsigned integer which indicates the number of "symbol" clocks between the first symbol of the next Sync byte and the next 3 ms marker.
+
+**Slot Number** is a 16-bit field which is defined as follows: (As mentioned in A.5.1.4, at least one packet with synchronization information must be sent in every period of 3 ms).
+
+##### **bit 0: slot position register enable** (msb)
+
+When this field has the value '1', the slot position register is valid. When this field has the value '0', the slot position register is not valid.
+
+##### **bit 1-3: reserved**
+
+**bit 4** is set to the value '1'. This bit is equivalent to M12 in the case of OOB downstream.
+
+##### **bit 5: odd parity**
+
+This bit provides odd parity for upstream slot position register. This bit is equivalent to M11 in the case of OOB downstream.
+
+##### **bits 6-15: upstream slot position register**
+
+The upstream slot position register is a 10 bit counter which counts from 0 to n with bit 6 the msb. These bits are equivalent to M10-M1 in the case of OOB downstream.
+
+(See A.5.4 for more information on the functionality of the upstream slot position register.)
+
+**MAC Flag Control** is a 24-bit field (b0, b1, b2...b23) which provides control information which is used in conjunction with the MAC Flags and Extension Flags. The definition of the MAC Flag Control field is as follows:
+
+- b0-b2 = channel 1 flag field control
+- b3-b5 = channel 2 flag field control
+- b6-b8 = channel 3 flag field control
+- b9-b11 = channel 4 flag field control
+- b12-b14 = channel 5 flag field control
+- b15-b17 = channel 6 flag field control
+- b18-b20 = channel 7 flag field control
+- b21-b23 = channel 8 flag field control
+
+Each of the above channel "x" flag field control fields are defined as follows:
+
+channel x flag control (a,b,c) = (bx, bx + 1, bx + 2)
+
+bit a: 0 – channel x flag field disabled
+
+1 – channel x flag field enabled
+
+bit b,c: 00 – all flags valid for second previous 3-ms period (out-of-band signalling equivalent)
+
+01 – flags valid for 1st ms of previous 3-ms period
+
+10 – flags valid for 2nd ms of previous 3-ms period
+
+11 – flags valid for 3rd ms of previous 3-ms period
+
+##### MAC Flags
+
+MAC Flags is a 26 byte field containing 8 slot configuration fields (24 bits each) which contain slot configuration information for the related upstream channels followed by two reserved bytes (first 3 bytes correspond to channel 1, second 3 bytes to channel 2, etc.). The definition of each slot configuration field is defined as follows:
+
+b0 = ranging control slot indicator for next 3-ms period (msb)
+
+b1-b6 = slot boundary definition field for next 3-ms period
+
+b7 = slot 1 reception indicator for [second] previous 3-ms period
+
+b8 = slot 2 reception indicator for [second] previous 3-ms period
+
+b9 = slot 3 reception indicator for [second] previous 3-ms period
+
+b10 = slot 4 reception indicator for [second] previous 3-ms period
+
+b11 = slot 5 reception indicator for [second] previous 3-ms period
+
+b12 = slot 6 reception indicator for [second] previous 3-ms period
+
+b13 = slot 7 reception indicator for [second] previous 3-ms period
+
+b14 = slot 8 reception indicator for [second] previous 3-ms period
+
+b15 = slot 9 reception indicator for [second] previous 3-ms period
+
+b16-b17 = reservation control for next 3 ms period
+
+b18-b23 = CRC-6 parity
+
+The slot configuration fields are used in conjunction with the MAC Flag Control field defined above. Note that when the MAC Flag Control field designates that a 1 ms flag update is enabled:
+
+- 1) the reception indicators refer to the previous 3-ms period (the bracketed term [second] is omitted from the definition);
+- 2) only the reception indicators which relate to slots which occur during the designated 1-ms period are valid; and
+- 3) the ranging control slot indicator, slot boundary definition field, and reservation control field are valid and consistent during each 3-ms period.
+
+###### Extension Flags
+
+Extension Flags is a 26-byte field which is used when one or more 3.088 Mbit/s upstream QPSK links are used. The definition of the Extension Flags field is identical to the definition of the MAC Flags field above.
+
+When 3.088 Mbit/s QPSK upstream links are used, each 3.088 Mbit/s upstream channel utilizes two consecutive `qpsk_slot_configuration` fields. The definition of the first slot configuration field is unchanged. The definition of the second slot configuration field extends the boundary definition to slots 10 through 18, and the reception indicators cover slots 10 through 18.
+
+##### MAC Message
+
+The MAC Message field contains a 40-byte message, the general format defined in A.5.5.
+
+**reserve field c** is a 4-byte field reserved for future use.
+
+#### A.5.3.3 Return Interaction path (upstream)
+
+##### A.5.3.3.1 Slot format
+
+The format of the upstream slot is shown in Figure A.21 below. A Unique Word (UW) (4 bytes) provides a burst mode acquisition method. The payload area (53 bytes) contains a single message cell. The RS Parity field (6 bytes) provides  $t = 3$  Reed-Solomon protection RS (59,53) over the payload area. The Guard band (1 byte) provides spacing between adjacent packets.
+
+![Figure A.21/J.112 – Slot format diagram](a003ffe7299e0a48bceb7f1e45a4f1a3_img.jpg)
+
+The diagram illustrates the format of an upstream slot. It is a horizontal bar divided into four segments: 'UW' (4 bytes), 'Payload area' (53 bytes), 'RS Parity' (6 bytes), and 'Guard band' (1 byte). Above the bar, double-headed arrows indicate the length of each segment. Below the bar, the labels 'UW', 'Payload area', 'RS Parity', and 'Guard band' are placed. A thick grey horizontal line runs along the bottom of the bar. In the bottom right corner, the text 'T0904560-97/d022' is present.
+
+Figure A.21/J.112 – Slot format diagram
+
+Figure A.21/J.112 – Slot format
+
+The structure and field coding of the message cell shall be consistent with the structure and coding given in Recommendation I.361 for ATM UNI.
+
+###### Unique word
+
+The unique word is four bytes long: CC CC CC 0D hex.
+
+###### ATM cell structure
+
+The format for each ATM cell structure is illustrated in Figure A.22. This structure and field coding shall be consistent with the structure and coding given in Recommendation I.361 for ATM UNI.
+
+![Figure A.22/J.112 – ATM cell format diagram](f943b07ab747bfd85e302e5a31c20ba8_img.jpg)
+
+The diagram illustrates the format of an ATM cell. It is a horizontal bar divided into two main segments: 'Header' (40 bits) and 'Information payload' (384 bits). Above the bar, double-headed arrows indicate the length of each segment in bits. Below the bar, the labels 'Header' and 'Information payload' are placed. A thick grey horizontal line runs along the bottom of the bar. Below the bar, a double-headed arrow indicates the total length of the cell as 53 bytes. In the bottom right corner, the text 'T0904570-97/d023' is present.
+
+Figure A.22/J.112 – ATM cell format diagram
+
+Figure A.22/J.112 – ATM cell format
+
+###### Channel coding
+
+Reed-Solomon encoding shall be performed on each ATM cell with  $T = 3$ . This means that 3 erroneous byte per ATM cell can be corrected. This process adds 6 parity bytes to the ATM cell to give a codeword of (59,53). The shortened Reed-Solomon Code shall be implemented by appending 196 bytes, all set to zero, before the information bytes at the input of a (255,249) encoder; after the coding procedure these bytes are discarded.
+
+The Reed-Solomon code shall have the following generator polynomials:
+
+- Code Generator Polynomial:  $g(x) = (x + \mu^0)(x + \mu^1)(x + \mu^2) \dots (x + \mu^5)$   
+where  $\mu = 02$  hex
+- Field Generator Polynomial:  $p(x) = x^8 + x^4 + x^3 + x^2 + 1$
+
+###### Guard band
+
+The guard band is 1 byte long (4 QPSK symbols). It provides some extra protection against synchronization errors.
+
+### A.5.4 Slot timing assignment
+
+#### A.5.4.1 Downstream slot position reference (downstream OOB)
+
+Upstream synchronization is derived from the downstream extended superframe (OOB) by noting the slot positions as shown in Table A.13.
+
+Table A.13/J.112 – Downstream slot position reference
+
+| Frame number | Bit number | Overhead bit | Slot position reference       |
+|--------------|------------|--------------|-------------------------------|
+| 1            | 0          | M1           | ♦ Slot position <sup>a)</sup> |
+| 2            | 193        | C1           |                               |
+| 3            | 386        | M2           |                               |
+| 4            | 579        | F1 = 0       |                               |
+| 5            | 772        | M3           |                               |
+| 6            | 965        | C2           |                               |
+| 7            | 1158       | M4           |                               |
+| 8            | 1351       | F2 = 0       |                               |
+| 9            | 1544       | M5           | ♦ Slot position               |
+| 10           | 1737       | C3           |                               |
+| 11           | 1930       | M6           |                               |
+| 12           | 2123       | F3 = 1       |                               |
+| 13           | 2316       | M7           |                               |
+| 14           | 2509       | C4           |                               |
+| 15           | 2702       | M8           |                               |
+| 16           | 2895       | F4 = 0       |                               |
+| 17           | 3088       | M9           | ♦ Slot Position               |
+| 18           | 3281       | C5           |                               |
+| 19           | 3474       | M10          |                               |
+| 20           | 3667       | F5 = 1       |                               |
+| 21           | 3860       | M11          |                               |
+| 22           | 4053       | C6           |                               |
+| 23           | 4246       | M12          |                               |
+| 24           | 4439       | F6 = 1       |                               |
+
+<sup>a)</sup> The first slot position is also called the 3-ms time marker in the case of 1.544 Mbit/s rate downstream. For the 3.088 Mbit/s rate downstream, the 3-ms time marker only appears once every two superframes. The M12 bit (see A.5.4) is used to differentiate between the two superframes.
+
+#### A.5.4.2 Downstream slot position reference (downstream IB)
+
+Upstream synchronization is derived from the downstream extended superframe (IB) by noting the 3-ms time Marker Downstream as shown in Figure A.23. From the bits of the Upstream Marker field contained in the MPEG-2 TS packet, the 3-ms time marker is obtained by counting a number of symbol clocks equal to (b23-b8). This marker is equivalent to the first slot position of the superframe for the OOB case.
+
+![Figure A.23/J.112 – Position of the 3-ms time marker for IB signalling. The diagram shows an MPEG-2 TS packet (188 bytes) followed by a 16-byte field and a Sync byte. A note below the packet states 'when Upstream Marker enable b0 = 1'. An arrow labeled '(b23-b8) in baud clocks' points from the Sync byte to a vertical dashed line labeled '3-ms time Marker Downstream'. The reference number T0904580-97/d024 is at the bottom right.](8f7c0bf0c75a31fee6b0c7392ff57c39_img.jpg)
+
+Figure A.23/J.112 – Position of the 3-ms time marker for IB signalling. The diagram shows an MPEG-2 TS packet (188 bytes) followed by a 16-byte field and a Sync byte. A note below the packet states 'when Upstream Marker enable b0 = 1'. An arrow labeled '(b23-b8) in baud clocks' points from the Sync byte to a vertical dashed line labeled '3-ms time Marker Downstream'. The reference number T0904580-97/d024 is at the bottom right.
+
+Figure A.23/J.112 – Position of the 3-ms time marker for IB signalling
+
+In order to describe how the US slot position is derived from the location of the DS 3-ms time marker at the NIU, consider the system diagrams in Figure A.24.
+
+![Figure A.24/J.112 – System model for timing analysis. This block diagram shows the flow of data through various delay stages. It starts with 'DATA' entering a delay block 'D_S', followed by 'D_1'. These are grouped under 'Headend delays'. Next is a large delay block 'D_IA', followed by 'D_2'. A vertical dashed line separates this from the 'Data link delays' section, which contains a delay block 'D_L + d_L'. Another vertical dashed line separates this from the 'Set-Top Box delays' section, which includes 'd_3', a large delay block 'D_IB', and 'd_4'. The reference number T0906040-98/d025 is at the bottom right.](9cbc1ebd80813fc36e499f7d70ed6881_img.jpg)
+
+Figure A.24/J.112 – System model for timing analysis. This block diagram shows the flow of data through various delay stages. It starts with 'DATA' entering a delay block 'D\_S', followed by 'D\_1'. These are grouped under 'Headend delays'. Next is a large delay block 'D\_IA', followed by 'D\_2'. A vertical dashed line separates this from the 'Data link delays' section, which contains a delay block 'D\_L + d\_L'. Another vertical dashed line separates this from the 'Set-Top Box delays' section, which includes 'd\_3', a large delay block 'D\_IB', and 'd\_4'. The reference number T0906040-98/d025 is at the bottom right.
+
+Figure A.24/J.112 – System model for timing analysis
+
+The delay between the location of the end of the Upstream Marker and the beginning of the next Sync byte, designated as  $D_S$ , is a constant value for each bit rate equal to the equivalent time of 197 bytes, or:
+
+$$(197 * 8 / x) \text{ symbol clocks}$$
+
+where:
+
+- $x = 4$ , for 16 QAM
+- 5, for 32-QAM
+- 6, for 64 QAM
+- 7, for 128-QAM
+- 8, for 256 QAM
+
+There will be some processing delay in the Headend hardware between the location where the Upstream Marker is inserted in the MAC packet and the arrival of the data into the interleaver. This should be a constant delay,  $D_1$ , which is the same for every incoming byte, including the sync byte following the Upstream Marker.
+
+The delay due to the interleaving process in the Headend is  $D_{IA}$  and will be zero for each sync byte.
+
+There will be some processing delay in the Headend hardware between the output of the interleaver and the output of the QAM modulator. This should be a constant delay,  $D_2$ , for every byte in the outgoing stream.
+
+The data link is composed of two delay values,  $D_L$ , the constant link delay that every STU experiences, and  $d_L$ , the variable link delay for each STU which is due to the fact that each STU is located at a different distance from the Headend. This variable link delay is compensated for by the ranging operation.
+
+There will be some processing delay in the STU hardware between the input of the QAM demodulator and the input of the de-interleaver. This delay is design dependent,  $d_3$ , and may be a constant delay or a variable delay for each byte in the data stream.
+
+The delay due to the de-interleaving process in the STU is  $D_{IB}$ , and will be equal to the entire interleave delay for each sync byte.
+
+The total interleave delay:
+
+$$D_I = D_{IA} + D_{IB}$$
+
+will be constant for each byte. The value will be given by:
+
+$$D_I = 204 * 8 * (\text{interleave\_depth}-1) / \text{bit rate}$$
+
+For example, if the modulation is QAM 64 with a baud rate of 5.0 Mbit/s:
+
+$$D_I = 204 * 8 * 11/30M = 598.4 \text{ microseconds or } 2992 \text{ symbol clocks}$$
+
+There will be some processing delay in the STU hardware between the output of the de-interleaver and the circuitry that utilizes the Upstream Marker and following sync byte for generating the local 3-ms marker. This delay, which includes Reed-Solomon FEC, is design dependent,  $d_4$ , and may be a constant delay or a variable delay for each byte in the data stream.
+
+The accumulated delay in the data link is composed of a number of constant terms and three variable terms. The constant terms will be identical for every STU that is utilizing a particular QAM channel for in-band timing and thus becomes a fixed offset between when the counter which is loading the Upstream Marker value and the actual location of the 3-ms marker at each STU. Each STU is responsible for compensating for the design dependent delays,  $d_3$  and  $d_4$ , before utilizing the Upstream Marker value for generating the 3-ms marker. The variable link delay,  $d_L$ , will be compensated for via the ranging algorithm, in the same way as performed when out-of-band signalling is employed.
+
+#### A.5.4.3 Upstream slot positions
+
+Transmission on each QPSK upstream channel is based on dividing access by multiple NIU units by utilizing a negotiated bandwidth allocation slot access method. A slotting methodology allows the transmit slot locations to be synchronized to a common slot position reference, which is provided via the related downstream MAC control channel. Synchronizing the slot locations increases message throughput of the upstream channels since the ATM cells do not overlap during transmission.
+
+The slot position reference for upstream slot locations is received via the related downstream MAC control channel by each NIU. Since each NIU receives the downstream slot position reference at a slightly different time, due to propagation delay in the transmission network, slot position ranging is required to align the actual slot locations for each related upstream channel. The upstream slot rates are 6000 upstream slots/s when the upstream data rate is 3088 Mbit/s, 3000 upstream slots/s when the upstream data rate is 1.544 Mbit/s and 500 upstream slots/s when the upstream data rate is 256 kbit/s.
+
+The number of slots available in any one second is given by:
+
+$$\text{number of slots/s} = \text{upstream data rate} / 512 + (\text{extra guardband})$$
+
+where extra guardband may be designated between groups of slots for alignment purposes.
+
+The Mbits in the SL-ESF serve two purposes:
+
+- to mark the slot positions for the upstream Contention based and Contentionless based signalling links (see A.5.4);
+- to provide slot count information for upstream message bandwidth allocation management in the NIU.
+
+Mbits M1, M5, and M9 mark the start of an upstream slot position for upstream message transmission.
+
+##### A.5.4.3.1 Rate 256 kbit/s
+
+In the case where the upstream data rate is 256 kbit/s and the downstream OOB rate is 1.544 Mbit/s, the upstream slots are numbered as follows:
+
+![Diagram showing a 6-ms time period (downstream) containing five slots: s(k-1), s(k), s(k+1), s(k+2), and s(k+3). Slot position references (downstream) are indicated by diamonds below the slots. The diagram is labeled T0904590-97/d026.](aeb2a26a07219661191294dba528067a_img.jpg)
+
+The diagram illustrates a 6-ms time period (downstream) divided into five slots:  $s(k-1)$ ,  $s(k)$ ,  $s(k+1)$ ,  $s(k+2)$ , and  $s(k+3)$ . Slot position references (downstream) are indicated by diamonds below the slots. The diagram is labeled T0904590-97/d026.
+
+Diagram showing a 6-ms time period (downstream) containing five slots: s(k-1), s(k), s(k+1), s(k+2), and s(k+3). Slot position references (downstream) are indicated by diamonds below the slots. The diagram is labeled T0904590-97/d026.
+
+where  $k$  is a multiple of 3. In the case where the downstream OOB rate is 3.088 Mbit/s, there are 12 slot position references downstream during the transmission of 3 upstream packets. In the case of IB downstream, packet "k" is sent when the 3-ms time marker is received.
+
+The relationship between the received slot position reference and the actual slot transmit position is given by:
+
+$$\text{slot\_transmit\_position} = \text{slot\_position\_reference (integer)} + \text{slot\_position\_offset}$$
+
+where only the  $\text{slot\_position\_references}$  corresponding to integer values are valid and the  $\text{slot\_position\_offset}$  is derived from the  $\text{Time\_Offset\_Value}$  provided via the  $\text{Range\_and\_Power\_Calibration\_Message}$  in the MAC protocol.
+
+![Diagram showing the relationship between slot transmit position, slot position reference, and slot position offset. It shows two slots, slot (j-1) and slot (j). The slot transmit position is indicated by an arrow pointing to the start of slot (j). The slot position offset is indicated by a double-headed arrow between the start of slot (j-1) and the slot transmit position. The diagram is labeled T0904600-97/d027.](ddfa5b18550d1a022a941e3c31843814_img.jpg)
+
+The diagram illustrates the relationship between the received slot position reference and the actual slot transmit position. It shows two slots,  $\text{slot } (j-1)$  and  $\text{slot } (j)$ . The  $\text{slot\_transmit\_position}$  is indicated by an arrow pointing to the start of  $\text{slot } (j)$ . The  $\text{slot\_position\_offset}$  is indicated by a double-headed arrow between the start of  $\text{slot } (j-1)$  and the  $\text{slot\_transmit\_position}$ . The diagram is labeled T0904600-97/d027.
+
+Diagram showing the relationship between slot transmit position, slot position reference, and slot position offset. It shows two slots, slot (j-1) and slot (j). The slot transmit position is indicated by an arrow pointing to the start of slot (j). The slot position offset is indicated by a double-headed arrow between the start of slot (j-1) and the slot transmit position. The diagram is labeled T0904600-97/d027.
+
+In the case where the upstream data rate is 256 kbit/s, the actual slot transmission locations correspond directly to the integer valued slot position references.
+
+##### A.5.4.3.2 Rate 1.544 Mbit/s
+
+In the case where the upstream data rate is 1.544 Mbit/s and the downstream OOB rate is 1.544 Mbit/s, the upstream slots are numbered as follows:
+
+![Diagram showing a 3-ms time period containing eleven slots: s(k-1), s(k), s(k+1), s(k+2), s(k+3), s(k+4), s(k+5), s(k+6), s(k+7), s(k+8), and s(k+9). Slot position references (downstream) are indicated by diamonds below the slots. The diagram is labeled T0904610-97/d028.](92c4d3a4d29d64c167855449f1aeba2a_img.jpg)
+
+The diagram illustrates a 3-ms time period divided into eleven slots:  $s(k-1)$ ,  $s(k)$ ,  $s(k+1)$ ,  $s(k+2)$ ,  $s(k+3)$ ,  $s(k+4)$ ,  $s(k+5)$ ,  $s(k+6)$ ,  $s(k+7)$ ,  $s(k+8)$ , and  $s(k+9)$ . Slot position references (downstream) are indicated by diamonds below the slots. The diagram is labeled T0904610-97/d028.
+
+Diagram showing a 3-ms time period containing eleven slots: s(k-1), s(k), s(k+1), s(k+2), s(k+3), s(k+4), s(k+5), s(k+6), s(k+7), s(k+8), and s(k+9). Slot position references (downstream) are indicated by diamonds below the slots. The diagram is labeled T0904610-97/d028.
+
+where  $k$  is a multiple of 9. In the case where the downstream OOB rate is 3.088 Mbit/s, there are 6 slot position references downstream during the transmission of 9 upstream packets. In the case of IB downstream, packet "k" is sent when the 3-ms time marker is received.
+
+The relationship between the received slot position reference and the actual slot transmit position is given by:
+
+$$\text{slot\_transmit\_position} = \text{slot\_position\_reference} + \text{slot\_position\_offset}$$
+
+where  $\text{slot\_position\_offset}$  is derived from the  $\text{Time\_Offset\_Value}$  provided via the  $\text{Range\_and\_Power\_Calibration\_Message}$  in the MAC protocol.
+
+![Diagram showing the relationship between slot transmit position and slot position reference. It shows two slots, Slot (j-1) and Slot (j). An arrow labeled 'slot_transmit_position' points to the start of Slot (j). A double-headed arrow labeled 'slot_position_offset' spans the gap between the start of Slot (j-1) and the start of Slot (j). A diamond labeled 'slot position reference (downstream)' is located at the start of Slot (j-1).](bccc028d0e75bc30c41528056f581545_img.jpg)
+
+Diagram showing the relationship between slot transmit position and slot position reference. It shows two slots, Slot (j-1) and Slot (j). An arrow labeled 'slot\_transmit\_position' points to the start of Slot (j). A double-headed arrow labeled 'slot\_position\_offset' spans the gap between the start of Slot (j-1) and the start of Slot (j). A diamond labeled 'slot position reference (downstream)' is located at the start of Slot (j-1).
+
+In the case where the upstream data rate is 1.544 Mbit/s, the actual slot transmission locations are given by:
+
+$$\text{slot\_transmission\_location}(m) = \text{slot\_transmit\_position} + (m \times 512)$$
+
+where  $m = 0, 1, 2$  is the position of the slot with respect to the  $\text{slot\_transmit\_position}$ . This leaves a free time interval ( $\text{FI} = 8$  bits) before the next  $\text{slot\_transmit\_position}$  occurs, during which no NIU transmits anything.
+
+![Diagram showing slot transmission locations. It shows a sequence of slots: Previous slot, Slot 0 (m=0), Slot 1 (m=1), Slot 2 (m=2), FI (8 bits), and Next slot. Arrows labeled 'slot_transmit_position' point to the start of Slot 0 and the start of the Next slot. Arrows labeled 'location 0', 'location 1', and 'location 2' point to the start of Slot 0, Slot 1, and Slot 2 respectively. Each slot (0, 1, 2) is 512 bits long.](c5a20f7bae219fc4c31f7376b7eb11e1_img.jpg)
+
+Diagram showing slot transmission locations. It shows a sequence of slots: Previous slot, Slot 0 (m=0), Slot 1 (m=1), Slot 2 (m=2), FI (8 bits), and Next slot. Arrows labeled 'slot\_transmit\_position' point to the start of Slot 0 and the start of the Next slot. Arrows labeled 'location 0', 'location 1', and 'location 2' point to the start of Slot 0, Slot 1, and Slot 2 respectively. Each slot (0, 1, 2) is 512 bits long.
+
+##### A.5.4.3.3 Rate 3.088 Mbit/s
+
+In the case where the upstream data rate is 3.088 Mbit/s and the downstream OOB rate is 1.544 Mbit/s, the upstream slots are numbered as shown below, where  $k$  is a multiple of 18.
+
+![Diagram showing a 3-ms time period containing 18 upstream slots. The slots are numbered s(k-1), k, k+1, k+2, k+3, k+4, k+5, k+6, k+7, k+8, k+9, k+10, k+11, k+12, k+13, k+14, k+15, k+16, k+17, and s(k+18). Arrows labeled 'slot_transmit_position' point to the start of slot k and the start of slot s(k+18). Diamonds labeled '3 slot position references (downstream) per 3-ms time period' are located at the start of slots k, k+9, and k+18.](f5d2a88925807080157c7cfb1d41cf0b_img.jpg)
+
+Diagram showing a 3-ms time period containing 18 upstream slots. The slots are numbered s(k-1), k, k+1, k+2, k+3, k+4, k+5, k+6, k+7, k+8, k+9, k+10, k+11, k+12, k+13, k+14, k+15, k+16, k+17, and s(k+18). Arrows labeled 'slot\_transmit\_position' point to the start of slot k and the start of slot s(k+18). Diamonds labeled '3 slot position references (downstream) per 3-ms time period' are located at the start of slots k, k+9, and k+18.
+
+In the case where the downstream OOB rate is 3.088 Mbit/s, there are 6 slot position references downstream during the transmission of 18 upstream packets. In the case of IB downstream, packet "k" is sent when the 3-ms time marker is received.
+
+The relationship between the received slot position reference and the actual slot transmit position is given by:
+
+$$\text{slot\_transmit\_position} = \text{slot\_position\_reference} + \text{slot\_position\_offset}$$
+
+where  $\text{slot\_position\_offset}$  is derived from the  $\text{Time\_Offset\_Value}$  provided via the  $\text{Range\_and\_Power\_Calibration\_Message}$ .
+
+![Diagram showing the relationship between slot position reference and slot transmit position. It illustrates Slot (j-1) and Slot (j) with a slot_position_offset between them. A slot transmit position is indicated at the start of Slot (j). A diamond symbol indicates the slot position reference (downstream).](0a73b03fba21af142d619a9a662e6490_img.jpg)
+
+The diagram shows two adjacent slots, Slot (j-1) and Slot (j). A vertical line separates them. A double-headed arrow labeled 'slot\_position\_offset' spans the gap between the end of Slot (j-1) and the start of Slot (j). A vertical line with a left-pointing arrow labeled 'slot\_transmit\_position' is located at the start of Slot (j). A diamond symbol labeled 'Slot position reference (downstream)' is located at the start of Slot (j-1). The text 'T0904650-97/d032' is in the bottom right of Slot (j).
+
+Diagram showing the relationship between slot position reference and slot transmit position. It illustrates Slot (j-1) and Slot (j) with a slot\_position\_offset between them. A slot transmit position is indicated at the start of Slot (j). A diamond symbol indicates the slot position reference (downstream).
+
+In the case where the upstream data rate is 3.088 Mbit/s, the actual slot transmission locations are given by:
+
+$$\text{slot\_transmission\_location (m)} = \text{slot\_transmit\_position} + (m * 512)$$
+
+where;  $m = 0, 1, 2, 3, 4, 5$  is the position of the slot with respect to the  $\text{slot\_transmit\_position}$ . This leaves a free time interval ( $\text{FI} = 16$  bits) before the next  $\text{slot\_transmit\_position}$  occurs, during which no NIU transmits anything.
+
+![Diagram showing the sequence of slots (Slot 0 to Slot 5) and the free interval (FI) between them. It includes labels for slot transmit positions and slot transmission locations (loc 0 to loc 5).](db5deafdae53dbc7d5972957f708c691_img.jpg)
+
+The diagram shows a sequence of slots. It starts with 'Previous slot', followed by Slot 0 (m=0), Slot 1 (m=1), Slot 2 (m=2), Slot 3 (m=3), Slot 4 (m=4), Slot 5 (m=5), a 'FI' (Free Interval) of 16 bits, and then 'Next slot'. Above the slots, arrows indicate 'slot\_transmit\_position' at the start of Slot 0 and Slot 5. Other arrows indicate 'loc 0' through 'loc 5' at various points within the slots. Below each slot (0-5), it says '512 bits'. The text 'T0904660-97/d033' is in the bottom right.
+
+Diagram showing the sequence of slots (Slot 0 to Slot 5) and the free interval (FI) between them. It includes labels for slot transmit positions and slot transmission locations (loc 0 to loc 5).
+
+#### A.5.4.4 Slot position counter
+
+Think of Mbits M10-M1 as a register (ESF counter), which counts from 0 to N, incrementing by one every 3-ms, where N an integer which indicates slot position cycle size (The value of N is calculated from  $\text{Service\_Channel\_Last\_Slot}$  sent in the MAC Default Configuration Message and the upstream bit rate of the service channel. For the case of a 256 kbit/s service channel, the maximum value of  $\text{Service\_Channel\_Last\_Slot}$  is 1535.). The upstream slot position register indicates the upstream slot positions that will correspond to the next SL-ESF frame. Upstream slot positions are counted from 0 to N. There are 6 upstream slots per ms when the upstream data rate is 3.088 Mbit/s, 3 upstream slots per ms when the upstream data rate is 1.544 Mbit/s, and there is 0.5 upstream slot per ms when the upstream data rate is 256 kbit/s. The corresponding upstream slot rates are, therefore, 6000 upstream slots/s
+
+when the upstream data rate is 3.088 Mbit/s, 3000 upstream slots/s when the upstream data rate is 1.544 Mbit/s, and 500 upstream slots/s when the upstream data rate is 256 kbit/s. The algorithm to determine the upstream slot position counter value is given below:
+
+```
+
+if (downstream_rate == 3.088 Mbit/s) {n = 1;}
+else      {n = 0;}
+upstream_slot_position_register = value of Mbits latched at bit_position M11 (M10-M1)
+if (upstream_rate == 1.544 Mbit/s)      {m = 3;}
+else if (upstream_rate == 3.088 Mbit/s)  {m = 6;}
+else      {m = 0.5}
+if (bit_position == M1 and previous M12 == 1)
+    { upstream_slot_position_counter = upstream_slot_position_register * 3 * m; }
+if (bit_position == M5)
+    if ( (n = 0) or (n == 1 and previous M12 == 0) )
+        { upstream_slot_position_counter = upstream_slot_position_counter + m; }
+if (bit_position == M9)
+    if ( (n = 0) or (n = 1 and previous M12 == 1) )
+        { upstream_slot_position_counter = upstream_slot_position_counter + m; }
+if (bit_position == M11)
+    { temp_upstream_slot_position_register = (M10, M9, M8, ..., M1); }
+if (bit_position == M12 and M12 == 1)
+    {upstream_slot_position_register = temp_upstream_slot_position_register;}
+
+```
+
+where the Mbits will be defined as follows:
+
+- M1-M10 = 10-bit ESF counter which counts from 0 to n with M10 the Most Significant Bit (MSB);
+- M11 = odd parity for the ESF counter, i.e. M11 = 1 if the ESF\_value (M1-M10) has an even number of bits set to 1;
+- M12 = 1: ESF counter valid;  
+0: ESF counter not valid.
+
+The values assigned to M12 are as follows:
+
+- 1) When the QPSK downstream channel bit rate is 1.544 Mbit/s, the M12 bit, is always set to the value '1'.
+- 2) When the QPSK downstream channel bit rate is 3.088 Mbit/s, the information is always transmitted in pairs of superframe, where superframe-A is the first superframe in the pair, and superframe-B is the second superframe in the pair. In this case, the M12 bit of superframe-A is set to the value '0' and the M12 bit of superframe-B is set to the value '1'.
+- 3) When the downstream channel is IB, M12 = 1.
+
+### A.5.5 MAC functionality
+
+#### A.5.5.1 MAC reference model
+
+The scope of this subclause is limited to the definition and specification of the MAC layer protocol. The detailed operations within the MAC layer are hidden from the above layers.
+
+This subclause focuses on the required message flows between the INA and the NIU for Media Access Control. These areas are divided into four categories: Initialization, Provisioning and Sign-on Management, Connection Management and Link Management (see Figure A.25).
+
+![Figure A.25/J.112 – MAC reference model diagram. The diagram shows the MAC reference model on the left and the IEEE 802 reference model on the right. The MAC reference model consists of 'Higher layers' at the top, a 'MAC sublayer' in the middle, and a 'Physical' layer at the bottom. The 'MAC sublayer' is further divided into a 'MAC management entity' (containing 'Link management', 'Connection management', and 'Initialization, sign-on and provisioning management'), 'Data application', 'MAC signalling', 'Multicast Address Resolution', and 'Singlecast Address Resolution'. The 'IEEE 802 reference model' on the right shows 'LLC', 'MAC', and 'Physical' layers. Arrows indicate the mapping: 'Higher layers' map to 'LLC', the 'MAC sublayer' maps to 'MAC', and the 'Physical' layer maps to 'Physical'. A vertical label 'Lower layer protocols' is on the left side of the MAC sublayer. A small text 'T0904670-97/d034' is at the bottom right.](b2cc37ae1974ec7b87b91f54963b855d_img.jpg)
+
+Figure A.25/J.112 – MAC reference model diagram. The diagram shows the MAC reference model on the left and the IEEE 802 reference model on the right. The MAC reference model consists of 'Higher layers' at the top, a 'MAC sublayer' in the middle, and a 'Physical' layer at the bottom. The 'MAC sublayer' is further divided into a 'MAC management entity' (containing 'Link management', 'Connection management', and 'Initialization, sign-on and provisioning management'), 'Data application', 'MAC signalling', 'Multicast Address Resolution', and 'Singlecast Address Resolution'. The 'IEEE 802 reference model' on the right shows 'LLC', 'MAC', and 'Physical' layers. Arrows indicate the mapping: 'Higher layers' map to 'LLC', the 'MAC sublayer' maps to 'MAC', and the 'Physical' layer maps to 'Physical'. A vertical label 'Lower layer protocols' is on the left side of the MAC sublayer. A small text 'T0904670-97/d034' is at the bottom right.
+
+Figure A.25/J.112 – MAC reference model
+
+#### A.5.5.2 MAC concept
+
+##### A.5.5.2.1 Relationship between higher layers and MAC protocol
+
+The goal of the MAC protocol is to provide tools for higher layer protocols in order to transmit and receive data transparently and independently of the physical layer. Higher layer services are provided by the INA to the STU. The INA is thus responsible of indicating the transmission mode and rate to the MAC layer for each type of service.
+
+Specifically, for each connection provided by higher layers on the INA side (VPI/VCI), a connection ID is associated at the MAC layer. The maximum number of simultaneous connections that a NIU should support is defined as follows:
+
+- Grade A: Only one connection at a time can be handled by a NIU.
+- Grade B: As many connections as needed, defined dynamically by the INA, following higher layers requests. Note that in this case, all connections should be assigned to the same frequency upstream and downstream for implementation reasons.
+
+Note however, that bandwidth (time slots) does not need to be assigned immediately by the INA for a given connection. This means that a connection ID may exist at the NIU side without associated slot numbers.
+
+The INA is responsible for providing transmission bandwidth to the NIUs when needed by higher layers. However, since the NIU must transmit all data from the STU, the NIU is also responsible for requesting for more bandwidth if not already provided by the INA.
+
+A default connection is initiated by the INA when STBs are first turned on. This connection can be used to send data from higher layers leading to further interactive connections. Note that this connection can be associated to a zero transmission rate (no initial bandwidth allocation).
+
+##### A.5.5.2.2 Relationship between physical layer and MAC protocol
+
+Up to 8 QPSK upstream channels can be related to each downstream channel which is designated as a MAC control channel. An example of frequency allocation is shown in Figure A.26. This relationship consists of the following items:
+
+- 1) Each of these related upstream channels share a common slot position. This reference is based on 1 ms time markers that are derived via information transmitted via the downstream MAC control channel.
+- 2) Each of these related upstream channels derive slot numbers from information provided in the downstream MAC control channel.
+- 3) The Messaging needed to perform MAC functions for each of these related upstream channels is transmitted via the downstream MAC control channel.
+
+The Media Access Control Protocol supports multiple downstream channels. In instances where multiple channels are used, the INA shall specify a single OOB frequency called the Provisioning Channel, where NIU's perform Initialization and Provisioning functions. If both 1.544 Mbit/s and 3.088 Mbit/s downstream OOB channels coexist on the network, there should be one Provisioning Channel with each rate. Also, in networks where IB NIUs exist, provisioning should be included in at least one IB channel. An aperiodic message is sent on each downstream control channel which points to the downstream Provisioning Channel. In instances where only a single frequency is in use, the INA shall utilize that frequency for Initialization and Provisioning functions.
+
+The Media Access Control protocol supports multiple upstream channels. One of the upstream channels shall be designated the Service Channel. The Service Channel shall be used by NIU's entering the network via the Initialization and Provisioning procedure. The remaining upstream channels shall be used for upstream data transmission. In cases where only one upstream channel is utilized, the functions of the Service Channel shall reside in conjunction with regular upstream data transmission (see Figure A.26).
+
+![Diagram illustrating frequency allocation for upstream and downstream channels. The diagram shows a horizontal line representing the frequency spectrum. On the left, there are two groups of eight upward-pointing arrows labeled '8-channels upstream'. Below the first group, an arrow points to one of the arrows labeled '1-service channel'. In the center, there are two downward-pointing arrows labeled 'Downstream channels'. On the right, there is one upward-pointing arrow labeled '1 provisioning channel'. Curved arrows labeled 'Related to' connect the '1-service channel' and the '1 provisioning channel' to the 'Downstream channels'. On the far right, a vertical double-headed arrow is labeled 'Upstream' at the top and 'Downstream' at the bottom. The text 'T0904680-97/d035' is at the bottom right.](ef5f5c6665b6ae13660ede412333ba45_img.jpg)
+
+Diagram illustrating frequency allocation for upstream and downstream channels. The diagram shows a horizontal line representing the frequency spectrum. On the left, there are two groups of eight upward-pointing arrows labeled '8-channels upstream'. Below the first group, an arrow points to one of the arrows labeled '1-service channel'. In the center, there are two downward-pointing arrows labeled 'Downstream channels'. On the right, there is one upward-pointing arrow labeled '1 provisioning channel'. Curved arrows labeled 'Related to' connect the '1-service channel' and the '1 provisioning channel' to the 'Downstream channels'. On the far right, a vertical double-headed arrow is labeled 'Upstream' at the top and 'Downstream' at the bottom. The text 'T0904680-97/d035' is at the bottom right.
+
+Figure A.26/J.112 – Example of frequency allocation
+
+##### A.5.5.2.3 Relationship between physical layer slot position counter and MAC slot assignment
+
+M10-M1 is a 10-bit superframe counter at the INA side, whereas the upstream slot position counter is an upstream slot counter at the NIUs side. The NIU slot position counter ( $M10-M1 \times 3 \times m$ , where  $m = 0.5$  for 256 kbit/s,  $m = 3$  for 1.544 Mbit/s and  $m = 6$  for 3.088 Mbit/s) may be implemented as a 16-bit counter which is compared to the 16-bit slot numbers assigned by the INA in MAC messages (list assignment). When the counter value equals any assigned value, the NIU is allowed to send a packet upstream.
+
+##### A.5.5.2.4 Access modes (Contention/Ranging/Fixed rate/Reservation)
+
+Different access modes are provided to the NIUs within access regions specified by information contained in the slot boundary fields of the downstream superframes. The limits between access regions allow users to know when to send data on contention without risks of collision with contentionless type data. Also, the separation between reservation and fixed rate regions provides two ways of assigning slots to NIUs. The following rules define how to select access modes:
+
+- *Data connections:*
+
+When the INA assigns a connection ID to the NIU, it either specifies a slot list to be used (Fixed rate access) or the NIU shall use contention or reserved access by following this algorithm:
+
+- When the NIU must send more cells than what was assigned by the INA, it can use contention access only if the number of cells to transmit is less than *Maximum\_contention\_access\_message\_length* (specified in the MAC Connect Message from the INA). In that case, it must wait for the slot reception indicator before it is allowed to send other cells with the same VPI/VCI value. The NIU can send one request for reservation access if the number of cells is less than *Maximum\_reservation\_access\_message\_length* (specified in the MAC Connect Message from the INA). If more cells must be transmitted, the NIU must send multiple requests for reservation access.
+
+- *MAC messages:*
+
+MAC messages can be sent on contention access or reservation access. MAC messages sent upstream must be less than 40 bytes long. If the MAC information exceeds 40 bytes, it must be segmented into multiple 40-bytes independent MAC messages. Ranging access can only be used for specific MAC messages.
+
+Note that the VPI/VCI=0/21 connection used for MAC messages is always set up, so the INA does not assign a particular connection ID which is normally used for reservation requests. Thus, in order to use reservation access, slots assigned for other connections may be used for MAC messages:
+
+- a) *Contention Access*
+
+Contention Access indicates that data (MAC or bursty data traffic) is sent in the slots assigned to the contention access region in the upstream channel. It can be used either to send MAC messages or data. The VPI, VCI of the ATM cells are then used to determine the type and direction of the data in higher layers. Contention based access provides instant channel allocation for the NIU.
+
+The Contention based technique is used for multiple subscribers that will have equal access to the signalling channel. It is probable that simultaneous transmissions will occur. For each ATM cell transmitted by the NIU, a positive acknowledgement is sent back by the INA, utilizing the reception indicator field, for each successfully received ATM cell. In contention based access mode, a positive acknowledgement indicates that a collision did not occur. A collision occurs if two or more NIUs attempt ATM cell transmission during the same slot. A collision will be assumed if a NIU does not receive a positive acknowledgement. If a collision occurs, then the NIU will retransmit using a procedure to be defined.
+
+For all the traffic sent contention access, a collision is assumed if the appropriate reception indicator of the slot used for transmission is not set. A counter at the NIU/STB records the number, denoted by `backoff_exponent`, of collisions encountered by a cell. The `backoff_exponent` counter starts from a value determined by the `Min_Backoff_Exponent` variable. The `backoff_exponent` is used to generate a uniform random number between 1 and  $2^{\text{backoff\_exponent}}$ . This random number is used to schedule retransmission of the collided cell. In particular, the random number indicates the number of contention access slots the NIU/STB shall wait before it transmits. The first transmission is carried out in a random cell within the contention based access region. If the counter reaches the maximum number, determined by the `Max_Backoff_Exponent` variable, the value of the counter remains at this value regardless of the number of subsequent collisions. After a successful transmission, the `backoff_exponent` counter is reset to a value determined by the `Min_Backoff_Exponent` variable. Informational Statement: The random access algorithm is unstable; the NRC is expected to have intelligence to detect an unstable state of the random access algorithm and to solve it.
+
+###### b) *Ranging Access*
+
+`Ranging Access` indicates that the data is sent in a slot preceded and followed by slots not used by other users. These slots allow users to adjust their clock depending on their distance to the INA such that their slots fall within the correct allocated time. They are either contention based when the ranging control slot indicator **b0** received during the previous superframe was 1 (or when b1-b6 = 55 to 63), or reserved if the INA indicates to the NIU that a specific slot is reserved for ranging.
+
+###### c) *Fixed rate Access*
+
+NOTE – Fixed rate is called contentionless in DAVIC.
+
+`Fixedrate Access` indicates that data is sent in slots assigned to the Fixed rate based access region in the upstream channel. These slots are uniquely assigned to a connection by the INA. No fixed rate access can be initiated by the NIU.
+
+###### d) *Reservation Access*
+
+`Reservation Access` implies that data is sent in the slots assigned to the reservation region in the upstream channel. These slots are uniquely assigned on a frame-by-frame basis to a connection by the INA. This assignment is made at the request of the NIU for a given connection.
+
+##### A.5.5.2.5 MAC error handling procedures
+
+Error handling procedures are under definition (Time out windows, power outage, etc.).
+
+##### A.5.5.2.6 MAC messages
+
+The MAC message types are divided into the logical MAC states of Initialization, Sign-on, Connection Management and Link Management. Messages in italic represent upstream transmission from NIU to INA. MAC messages are sent using Broadcast or Singlecast Addressing. Singlecast address shall utilize the 48-bit MAC address (see Table A.14).
+
+**Table A.14/J.112 – MAC messages**
+
+| Message type value |                                                              | Addressing type |
+|--------------------|--------------------------------------------------------------|-----------------|
+|                    | <b>MAC Initialization, Provisioning and Sign-On messages</b> |                 |
+| 0x01               | Provisioning Channel message                                 | Broadcast       |
+| 0x02               | Default Configuration message                                | Broadcast       |
+| 0x03               | Sign-on Request message                                      | Broadcast       |
+| 0x04               | <i>Sign-on Response message</i>                              | Singlecast      |
+| 0x05               | Ranging and Power Calibration message                        | Singlecast      |
+| 0x06               | <i>Ranging and Power Calibration Response message</i>        | Singlecast      |
+| 0x07               | Initialization Complete message                              | Singlecast      |
+| 0x08-0x1F          | [Reserved]                                                   |                 |
+| 0x20-0x3F          | <b>MAC Connection Establishment and Termination messages</b> |                 |
+| 0x20               | Connect message                                              | Singlecast      |
+| 0x21               | <i>Connect Response message</i>                              | Singlecast      |
+| 0x22               | <i>Reservation Request message</i>                           | Singlecast      |
+| 0x23               | Reservation Response message                                 | Broadcast       |
+| 0x24               | Connect Confirm message                                      | Singlecast      |
+| 0x25               | Release message                                              | Singlecast      |
+| 0x26               | <i>Release Response message</i>                              | Singlecast      |
+| 0x28               | Reservation Grant message                                    | Broadcast       |
+| 0x29               | Reservation ID Assignment                                    | Singlecast      |
+| 0x2A               | <i>Reservation Status Request</i>                            | Singlecast      |
+| 0x2B               | <i>Reservation ID Response message</i>                       | Singlecast      |
+| 0x2C-0x3F          | [Reserved]                                                   |                 |
+|                    | <b>MAC Link Management messages</b>                          |                 |
+| 0x27               | <i>Idle message</i>                                          | Singlecast      |
+| 0x40               | Transmission Control message                                 | Scast or Bcast  |
+| 0x41               | Reprovision message                                          | Singlecast      |
+| 0x42               | <i>Link Management Response message</i>                      | Singlecast      |
+| 0x43               | Status Request message                                       | Singlecast      |
+| 0x44               | <i>Status Response message</i>                               | Singlecast      |
+| 0x45-0x5F          | [Reserved]                                                   |                 |
+
+To support the delivery of MAC related information to and from the NIU, a dedicated Virtual Channel shall be utilized. The VPI,VCI for this channel shall be 0x000,0x0021:
+
+###### - *Upstream MAC messages*
+
+AAL5 (as specified in Recommendation I.363) adaptation shall be used to encapsulate each MAC PDU in an ATM cell. Upstream MAC information should be single 40-bytes cell messages.
+
+###### - *Downstream OOB MAC messages*
+
+AAL5 (as specified in Recommendation I.363) adaptation shall be used to encapsulate each MAC PDU in an ATM cell. Downstream OOB MAC information may be longer than 40-bytes.
+
+###### - Downstream IB MAC messages
+
+Downstream IB MAC information is limited to 120-bytes long messages. Longer messages must be split into separate messages. No AAL5 layer is defined for MPEG-2 TS cells. MAC messages must therefore be sent as explained in Figure A.27.
+
+![Flowchart illustrating the algorithm for detecting MAC messages when sent IB downstream. The process starts with checking the first MAC message field. If the first two bytes are zero, no messages are detected. If not zero, it checks if the length is greater than 40 bytes. If yes, it checks if the length is greater than 80 bytes. If yes, a single MAC message is detected. If no, it checks the second MAC message field. If the first two bytes of the second field are zero, two MAC messages are detected. If not zero, it checks if the length of the second field is greater than 40 bytes. If yes, two MAC messages are detected. If no, it checks the third MAC message field. If the first two bytes of the third field are zero, three MAC messages are detected. If not zero, it checks the third MAC message field again. If the first two bytes are zero, two MAC messages are detected. If not zero, one MAC message is detected.](b4b91e1f5ced9a2bc4a7f3b038cf3fb6_img.jpg)
+
+```
+
+graph TD
+    A[Check first MAC message field] --> B[Are the first two bytes of MAC message equal to zero?]
+    B -- Yes --> C[No MAC messages detected]
+    B -- No --> D[Is the length of message in first field greater than 40 bytes?]
+    D -- Yes --> E[Is the length of the message greater than 80 bytes?]
+    D -- No --> F[Check second MAC message field]
+    E -- Yes --> G[Single MAC message detected]
+    E -- No --> H[Check third MAC message field]
+    F --> I[Are the first two bytes of MAC message equal to zero?]
+    I -- Yes --> J[Two MAC messages detected]
+    I -- No --> K[Is the length of message in second field greater than 40 bytes?]
+    K -- Yes --> J
+    K -- No --> L[Check third MAC message field]
+    L --> M[Are the first two bytes of the MAC message equal to zero?]
+    M -- No --> N[Three MAC messages detected]
+    M -- Yes --> O[Two MAC messages detected]
+    H --> P[Are the first two bytes of the MAC message equal to zero?]
+    P -- No --> O
+    P -- Yes --> Q[One MAC message detected]
+  
+```
+
+T0904690-97/d036
+
+Flowchart illustrating the algorithm for detecting MAC messages when sent IB downstream. The process starts with checking the first MAC message field. If the first two bytes are zero, no messages are detected. If not zero, it checks if the length is greater than 40 bytes. If yes, it checks if the length is greater than 80 bytes. If yes, a single MAC message is detected. If no, it checks the second MAC message field. If the first two bytes of the second field are zero, two MAC messages are detected. If not zero, it checks if the length of the second field is greater than 40 bytes. If yes, two MAC messages are detected. If no, it checks the third MAC message field. If the first two bytes of the third field are zero, three MAC messages are detected. If not zero, it checks the third MAC message field again. If the first two bytes are zero, two MAC messages are detected. If not zero, one MAC message is detected.
+
+Figure A.27/J.112 – Algorithm when MAC messages are sent IB downstream
+
+Since MAC related information is terminated at the NIU and INA, a privately defined message structure will be utilized. The format of this message structure is illustrated in Table A.15.
+
+NOTE 1 – All messages are sent most significant bit first.
+
+NOTE 2 – For all MAC messages where the parameter length is smaller than the field, the parameter shall be right justified with leading bits set to 0. All reserved fields in the MAC messages shall be set to 0.
+
+NOTE 3 – Message 0x23 is not used in the present release of the MAC protocol. It refers to DAVIC 1.0 protocol which is not supported by this specification.
+
+NOTE 4 – When no MAC\_Address is specified in the message, it means that the message is sent broadcast. (Syntax\_indicator = 000)
+
+NOTE 5 – Negative integers are sent in 2's complement.
+
+**Table A.15/J.112 – MAC message structure**
+
+|                                   | Bits        | Bytes      | Bit number/Description |
+|-----------------------------------|-------------|------------|------------------------|
+| MAC_message() {                   |             |            |                        |
+| <b>Message_Configuration</b>      | <b>8</b>    | <b>1</b>   |                        |
+| Protocol_Version                  | 5           |            |                        |
+| Syntax_Indicator                  | 3           |            |                        |
+| <b>Message_Type</b>               | <b>8</b>    | <b>1</b>   |                        |
+| If (syntax_indicator==001) {      |             |            |                        |
+| <b>MAC_Address</b>                | <b>(48)</b> | <b>(6)</b> |                        |
+| }                                 |             |            |                        |
+| {                                 |             |            |                        |
+| <b>MAC_Information_Elements()</b> |             | <b>N</b>   |                        |
+| } }                               |             |            |                        |
+
+###### Protocol Version
+
+Protocol\_Version is a 5-bit field used to identify the current MAC version. The value for this parameter is given in Table A.16.
+
+**Table A.16/J.112 – Protocol\_version coding**
+
+| Value | Definition                                                          |
+|-------|---------------------------------------------------------------------|
+| 0     | DAVIC 1.0 compliant device (not consistent with this specification) |
+| 1     | DAVIC 1.1 compliant device                                          |
+| 2     | DAVIC 1.2 compliant device                                          |
+| 3-31  | Reserved                                                            |
+
+###### Syntax Indicator
+
+Syntax\_Indicator is a 3-bit enumerated type that indicates the addressing type contained in the MAC message.
+
+|                                                                             |
+|-----------------------------------------------------------------------------|
+| Enum Syntax_Indicator {No_MAC_Address, MAC_Address_Included, reserved2..7}; |
+|-----------------------------------------------------------------------------|
+
+###### MAC Address
+
+MAC\_Address is a 48-bit value representing the unique MAC address of the NIU. This MAC address may be hard coded in the NIU or be provided by external source.
+
+#### A.5.5.3 MAC Initialization and Provisioning
+
+This subclause defines the procedure for Initialization and Provisioning that the MAC shall perform during power on or Reset.
+
+- 1) Upon a NIU becoming active (i.e. powered up), it must first find the current provisioning frequency. The NIU shall receive the <MAC> **Provisioning Channel Message**. This message shall be sent aperiodically on all downstream OOB channels when there are multiple channels. In the case of only a single channel, the message shall indicate the current channel to be utilized for Provisioning. Upon receiving this message, the NIU shall tune to the Provisioning Channel. In the case of IB downstream, the IB channel to be used during provisioning must be given by using ETS 300 468, no <MAC> Provisioning Channel Message is needed.
+- 2) After a valid lock indication on a Provisioning Channel, the NIU shall await the <MAC> **DEFAULT CONFIGURATION MESSAGE**. When received, the NIU shall configure its parameters as defined in the default configuration message. The Default Configuration Parameters shall include default timer values, default power levels, default retry counts as well as other information related to the operation of the MAC protocol.
+
+Figure A.28 shows the signalling sequence.
+
+![Sequence diagram showing signaling between INA and NIU/STB. INA sends a <MAC> Provisioning Channel message to NIU/STB, followed by a <MAC> Default Configuration message. Reference T0904700-97/d037 is shown at the bottom right.](376f80eb8a41369e87da63a0210d173e_img.jpg)
+
+```
+
+sequenceDiagram
+    participant INA
+    participant NIU/STB
+    Note right of NIU/STB: T0904700-97/d037
+    INA->>NIU/STB: <MAC> Provisioning Channel message
+    INA->>NIU/STB: <MAC> Default Configuration message
+  
+```
+
+Sequence diagram showing signaling between INA and NIU/STB. INA sends a  Provisioning Channel message to NIU/STB, followed by a  Default Configuration message. Reference T0904700-97/d037 is shown at the bottom right.
+
+Figure A.28/J.112 – Initialization and Provisioning signalling
+
+##### A.5.5.3.1 <MAC> Provisioning Channel Message (broadcast OOB downstream)
+
+The <MAC> PROVISIONING CHANNEL MESSAGE is sent by the INA to direct the NIU to the proper Out-of-Band frequency where provisioning is performed. The format of the message is shown in Table A.17.
+
+Table A.17/J.112 – Provisioning Channel Message format
+
+|                                               | Bits | Bytes | Bit number/Description |
+|-----------------------------------------------|------|-------|------------------------|
+| Provisioning_Channel_Message() {              |      |       |                        |
+| <b>Provisioning_Channel_Control_Field</b>     | 8    | 1     |                        |
+| <i>reserved</i>                               | 7    |       | 7-1:                   |
+| <i>provisioning_frequency_included</i>        | 1    |       | 0: {no=0, yes=1}       |
+| <i>if (provisioning_frequency_included) {</i> |      |       |                        |
+| <b>Provisioning_Frequency</b>                 | (32) | (4)   |                        |
+| <b>DownStream_Type</b>                        | 8    | 1     |                        |
+| <i>}</i>                                      |      |       |                        |
+| }                                             |      |       |                        |
+
+###### Provisioning Channel Control Field
+
+Provisioning\_Channel\_Control\_Field is used to specify the downstream frequency where the NIU will be provisioned.
+
+###### Provisioning Frequency Included
+
+provisioning\_frequency\_included is a boolean when set, indicates that a downstream OOB frequency is specified that the NIU should tune to begin the provisioning process. When cleared, indicates that the current downstream frequency is the provisioning frequency.
+
+###### Provisioning Frequency
+
+Provisioning\_Frequency is a 32-bit unsigned integer representing the Out-of-band Frequency in which NIU provisioning occurs. The unit of measure is Hz.
+
+###### Downstream Type
+
+DownStream\_Type is an 8-bit enumerated type indicating the modulation format for the down stream connection. {reserved, QPSK\_1.544, QPSK\_3.088, 3..255 reserved}
+
+##### A.5.5.3.2 <MAC> Default Configuration Message (broadcast downstream)
+
+The <MAC> DEFAULT CONFIGURATION MESSAGE is sent by the INA to the NIU. The message provides default parameter and configuration information to the NIU. The format of the message is shown in Table A.18.
+
+Table A.18/J.112 – Default configuration message structure
+
+|                                      | Bits | Bytes | Bit number/Description |
+|--------------------------------------|------|-------|------------------------|
+| Default_Configuration_Message() {    |      |       |                        |
+| Sign_On_Incr_Pwr_Retry_Count         | 8    | 1     |                        |
+| Service_Channel_Frequency            | 32   | 4     |                        |
+| Service_Channel_Control_Field        |      | 1     |                        |
+| MAC_Flag_Set                         | 5    |       | 7-3                    |
+| Service_Channel                      | 3    |       | 2-0                    |
+| Backup_Service_Channel_Frequency     | 32   | 4     |                        |
+| Backup_Service_Channel_Control_Field |      | 1     |                        |
+| Backup_MAC_Flag_Set                  | 5    |       | 7-3                    |
+| Backup_Service_Channel               | 3    |       | 2-0                    |
+| Service_Channel_Frame_Length         | 16   | 2     |                        |
+| Service_Channel_Last_Slot            | 16   | 2     |                        |
+| Max_Power_Level                      | 8    | 1     |                        |
+| Min_Power_Level                      | 8    | 1     |                        |
+| Upstream_Transmission_Rate           | 3    | 1     | {enum}                 |
+| Max_Backoff_Exponent                 | 8    | 1     |                        |
+| Min_Backoff_Exponent                 | 8    | 1     |                        |
+| Idle_Interval                        | 16   | 2     |                        |
+| }                                    |      |       |                        |
+
+###### Sign-On Increment Power Retry Count
+
+`Sign_On_Incr_Pwr_Retry_Count` is an 8-bit unsigned integer representing the number of attempts the NIU should try to enter the system at the same power level before incrementing its power level by steps of 0.5 dB.
+
+###### Service Channel Frequency
+
+`Service_Channel_Frequency` is a 32-bit unsigned integer representing the upstream frequency assigned to the service channel. The unit of measure is in Hz.
+
+###### MAC\_Flag\_Set
+
+`MAC_Flag_Set` is a 5-bit field representing the MAC Flag set assigned to the service channel (i.e. R1a, R1b and R1c represent MAC Flag set 1). In the OOB downstream SL-ESF frame payload structure, each set of three bytes, denoted by Rxa-Rxc, comprise a Flag set. These eight flag sets are assigned the numbers 1-8. In the IB downstream timing, the 16 flag sets are assigned the numbers 1-16. In the case of a 3.088 Mbit/s upstream channel, two successive flag sets are required to define a 3-ms period. In this case, this parameter represents the first of two successively assigned flag sets. In the case of a 3.088 Mbit/s OOB downstream, two successive SL-ESF frames define the 3-ms interval. The Rxa-Rxc bytes of the first frame represent flag sets 1-8 while the Rxa-Rxc bytes of the second frame represent flag sets 9-16.
+
+A downstream channel contains control information for each of its associated upstream channels. This information is contained within structures known as MAC Flags. A set of MAC Flags, represented by either 24 bits (denoted b0-b23) or by 3 bytes (denoted Rxa, Rxb and Rxc), are uniquely assigned to a given upstream channel.
+
+In the OOB downstream case, each SL-ESF frame structure contains eight sets of MAC Flags represented by Rxa, Rxb and Rxc, where x is replaced by the numbers 1-8. In the case of a 1.544 Mbit/s downstream bit rate, only one SL-ESF frame occurs during a 3-ms interval providing 8 sets of MAC Flags. In the case of a 3.088 Mbit/s downstream bit rate, two SL-ESF frames occur during a 3-ms interval, providing 16 sets of MAC Flags. The second set of MAC Flags (contained in the second SL-ESF) are denoted by Rxa, Rxb and Rxc, where x is replaced by the numbers 9 through 16.
+
+In the IB downstream case, the MAC Flags are contained in the MAC Control Message Structure which can contain as many as 16 MAC Flag sets. The MAC Flags 1-8 are contained in the "MAC Flags" field and the MAC Flags 9-16 are contained in the "Extension Flags" field.
+
+In case of a 3.088 Mbit/s upstream channel, two sets of MAC Flags are required. In this case, the `MAC_Flag_Set` parameter represents the first of two successively assigned MAC Flag sets.
+
+###### Service Channel
+
+`Service_Channel` is a 3-bit field which defines the channel assigned to the `Service_Channel_Frequency`. Although the function provided by this parameter is superseded in this specification by the `MAC_Flag_Set`, it is retained in order to identify the logical channel assigned to the NIU/STB.
+
+###### Backup Service Channel Frequency
+
+`Backup_Service_Channel_Frequency` is a 32-bit unsigned integer representing the upstream frequency assigned to the backup service channel. The backup service channel is used when entry on the primary service channel fails. The unit of measure is in Hz.
+
+###### **Backup\_MAC\_Flag\_Set**
+
+Backup\_MAC\_Flag\_Set is a 5-bit field representing the MAC Flag set assigned to the backup service channel. The function of this field is the same as the MAC\_Flag\_Set above but with respect to the backup service channel.
+
+###### **Backup\_Service Channel**
+
+Backup\_Service\_Channel is a 3-bit field which defines the channel assigned to the Backup\_Service\_Channel\_Frequency. The function of this field is the same as the Service\_Channel above but with respect to the backup channel.
+
+###### **Service\_Channel\_Frame\_Length [reserved]**
+
+Unused in this version.
+
+###### **Service Channel Last Slot**
+
+Service\_Channel\_Last\_Slot is a 16-bit unsigned integer representing the largest slot value of the NIU slots position counter ( $N \times 3 \times m$ , where  $N$  is defined in A.5.4.3). In general, this value will be used for all other upstream channels. It will be a multiple of 3, 9 or 18 for 256 kbit/s, 1.544 Mbit/s, or 3.088 Mbit/s respectively.
+
+###### **Maximum Power Level**
+
+MAX\_Power\_Level is an 8-bit unsigned integer representing the maximum power the NIU shall be allowed to use to transmit upstream. The unit of measure is in dBmicroV (RMS) on 75  $\Omega$ .
+
+###### **Minimum Power Level**
+
+MIN\_Power\_Level is an 8-bit unsigned integer representing the minimum power the NIU shall be allowed to use to transmit upstream. The unit of measure is in dBmicroV (RMS) on 75  $\Omega$ .
+
+###### **Upstream Transmission Rate**
+
+Upstream\_Transmission\_Rate is a 3-bit enumerated type that indicates the upstream transmission rate.
+
+|                                                                                                  |
+|--------------------------------------------------------------------------------------------------|
+| enum Upstream_Transmission_Rate {Upstream_256K, Upstream_1-544M, Upstream_3-088M, reserved3..7}; |
+|--------------------------------------------------------------------------------------------------|
+
+###### **MIN\_Backoff\_Exponent**
+
+MIN\_Backoff\_Exponent is an 8-bit unsigned integer representing the minimum value of the backoff exponent counter.
+
+###### **MAX\_Backoff\_Exponent**
+
+MAX\_Backoff\_Exponent is an 8-bit unsigned integer representing the minimum value of the backoff exponent counter.
+
+###### **Idle\_Interval**
+
+Idle\_Interval is a 16-bit unsigned integer representing the predefined interval for the MAC Idle messages. The unit of the measure is in milliseconds.
+
+#### A.5.5.4 Sign-On and Calibration
+
+The NIU shall Sign On via the Sign-On procedure. The signalling flow for Sign-On is described below:
+
+- The NIU shall tune to the downstream Provisioning Channel and the upstream Service Channel with the information provided in the Initialization and Provisioning sequence.
+- The NIU shall await the <MAC> **Sign-On Request Message** from the INA Entity. The NIU shall utilize Contention based entry on the Service Channel to access the network.
+- Upon receiving the <MAC> **Sign-On Request Message**, the NIU shall respond with the <MAC> **Sign-On Response Message**. The Sign-On Response message shall be transmitted on a Ranging Control Slot.
+- The INA, upon receiving the Sign-On Response message shall validate the NIU and send the <MAC> **Ranging and Power Calibration Message**.
+- The NIU shall respond to the <MAC> **Ranging and Power Calibration Message** with the <MAC> **Ranging and Power Calibration Response Message**. The <MAC> **Ranging and Power Calibration Response Message** shall be transmitted on a Ranging Control Slot (which can either be in the ranging region ( $b0 = 1$ ) or reserved region (if a ranging slot number is given in the message)).
+- The INA shall send the <MAC> **Initialization Complete Message** when the NIU is calibrated. The NIU is assumed to be calibrated if the message arrives within a window of 1.5 symbols (upstream rate) and a power within a window of 1.5 dB from their optimal value.
+
+![Sequence diagram showing the ranging and calibration signalling between INA and NIU/STB.](5801c19431e76330430e92a598cc7a16_img.jpg)
+
+```
+sequenceDiagram
+    participant INA
+    participant NIU/STB
+    INA->>NIU/STB: <MAC> Sign-on message
+    NIU/STB-->>INA: <MAC> Sign-on Response message
+    INA->>NIU/STB: <MAC> Ranging and Power Calibration message
+    NIU/STB-->>INA: <MAC> Ranging and Power Calibration Response message
+    INA->>NIU/STB: <MAC> Initialization Complete
+```
+
+The diagram illustrates the interaction between the INA (Initiation Entity) and the NIU/STB (Network Interface Unit/Service Terminal Base). The sequence of messages is as follows: 1. INA sends a <MAC> Sign-on message to NIU/STB. 2. NIU/STB responds with a <MAC> Sign-on Response message. 3. INA sends a <MAC> Ranging and Power Calibration message. 4. NIU/STB responds with a <MAC> Ranging and Power Calibration Response message. 5. INA sends a <MAC> Initialization Complete message. The diagram is labeled with 'INA' on the left and 'NIU/STB' on the right. A reference code 'T0904710-97/d038' is present at the bottom right of the diagram.
+
+Sequence diagram showing the ranging and calibration signalling between INA and NIU/STB.
+
+Figure A.29/J.112 – Ranging and calibration signalling
+
+Figure A.30 state diagram details the procedure described above.
+
+![State diagram for Ranging and calibration. The diagram shows a sequence of states: 'Wait for Sign-On Request', 'Wait Random Time < Time Window', 'Wait for a new Time Window', 'Modify Power and Ranging' (left), 'Modify Power and Ranging' (right), and 'END'. Transitions include 'Receive Sign-On Request', 'Send Sign-On Response message on a Ranging Slot', 'Ranging and Control message + Ranging Slot Number', 'R and C message and no Ranging Slot Number', 'Initialization Complete', and 'Time elapsed'.](29fbbed4c4aff19e9ac5bf98e0c9b24d_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> WaitSignOn
+    state "Wait for Sign-On Request" as WaitSignOn
+    state "Wait Random Time < Time Window<br/>Retry or increase Power<sup>a)</sup><br/>Send Sign-On Response message<br/>on a Ranging Slot" as WaitRandomTime
+    state "Wait for a new Time Window" as WaitNewTimeWindow
+    state "Modify Power and Ranging.<br/>Send a Ranging and<br/>Control Response on the Ranging<br/>Slot Number given by the INA<br/>and wait for Initialization<br/>Complete or Ranging and Control message." as ModifyPowerLeft
+    state "Modify Power and Ranging.<br/>Send a Ranging and Control<br/>Response in a contention based<br/>Ranging Slot. Wait for Initialization<br/>Complete or Ranging and<br/>Control message." as ModifyPowerRight
+    state END
+
+    WaitSignOn --> WaitRandomTime : Receive Sign-On Request
+    WaitRandomTime --> WaitNewTimeWindow
+    WaitNewTimeWindow --> ModifyPowerLeft : Ranging and Control message + Ranging Slot Number
+    WaitNewTimeWindow --> ModifyPowerRight : Ranging and Control message and no Ranging Slot Number
+    ModifyPowerLeft --> END : Initialization Complete
+    ModifyPowerRight --> END : Initialization Complete
+    ModifyPowerLeft --> WaitSignOn : Time elapsed
+    ModifyPowerRight --> WaitSignOn : If time > Time Window
+    ModifyPowerLeft --> ModifyPowerRight : R and C message and no Ranging Slot Number
+    ModifyPowerRight --> ModifyPowerLeft : R and C message + Ranging Slot Number
+    
+```
+
+State diagram for Ranging and calibration. The diagram shows a sequence of states: 'Wait for Sign-On Request', 'Wait Random Time < Time Window', 'Wait for a new Time Window', 'Modify Power and Ranging' (left), 'Modify Power and Ranging' (right), and 'END'. Transitions include 'Receive Sign-On Request', 'Send Sign-On Response message on a Ranging Slot', 'Ranging and Control message + Ranging Slot Number', 'R and C message and no Ranging Slot Number', 'Initialization Complete', and 'Time elapsed'.
+
+T0904720-97/d039
+
+a) "Retry or Increase Power" means that the NIU should retry with the same power Sign\_On\_Incr\_Pwr\_Retry\_Count times (given by the <MAC> default configuration message) and then increase the power by 0.5 dB.
+
+Figure A.30/J.112 – State diagram for Ranging and calibration
+
+NOTE – The Ranging and Control message shown in Figure A.30 corresponds to the <MAC> Ranging and Power Calibration Message. The Ranging and Control Response corresponds to the <MAC> Ranging and Power Calibration Response Message. "Sign-On Request" stands for <MAC> Sign-On Request Message, and similarly, "Sign-On Response" stands for <MAC> Sign-On Response Message.
+
+##### A.5.5.4.1 <MAC> Sign-On Request Message (broadcast downstream)
+
+The <MAC> SIGN-ON REQUEST message is issued periodically by the INA to allow a NIU to indicate its presence in the network. The format of this subcommand is shown in Table A.19.
+
+Table A.19/J.112 – Sign-on Request message structure
+
+|                                  | Bits | Bytes | Bit number/Description |
+|----------------------------------|------|-------|------------------------|
+| Sign-On_Request_Message() {      |      |       |                        |
+| Sign-On_Control_Field            | 8    | 1     |                        |
+| Reserved                         | 7    |       | 7-1                    |
+| Address_Filter_Params_Included   | 1    |       | 0: {no,yes}            |
+| Response_Collection_Time_Window  | 16   | 2     |                        |
+| if (Sign-On_Control_Field=       |      |       |                        |
+| Address_Filter_Params_Included { |      |       |                        |
+| Address_Position_Mask            | (8)  | (1)   |                        |
+| Address_Comparison_Value         | (8)  | (1)   |                        |
+| }                                |      |       |                        |
+| }                                |      |       |                        |
+
+###### Sign-On Control Field
+
+Sign-On\_Control\_Field specifies what parameters are included in the SIGN-ON REQUEST.
+
+###### Address Filter Parameters Included
+
+address\_filter\_params\_included is a boolean, when set, indicates that the NIU should respond to the SIGN-ON REQUEST only if its address matches the filter requirements specified in the message.
+
+###### Response Collection Time Window
+
+Response\_Collection\_Time\_Window is a 16-bit unsigned integer that specifies the duration of time the NIU has to respond to the SIGN-ON REQUEST. The unit of measure is the millisecond (ms).
+
+###### Address Position Mask
+
+Address\_Position\_Mask is an 8-bit unsigned integer that indicates the bit positions in the NIU MAC address that are used for address filtering comparison. The bit positions are comprised between bit number Mask and Mask+7. Mask = 0 corresponds to the 8 LSBs of the address, i.e. it represents the number of bits shifted to the left. The maximum value is 40.
+
+###### Address Comparison Value
+
+Address\_Comparison\_Value is an 8-bit unsigned integer that specifies the value that the NIU should use for MAC address comparison (see Figure A.31).
+
+![Diagram showing the position of a Mask in a MAC address. The MAC address is 6 bytes (48 bits) long, with MSB on the left and LSB on the right. A Mask field is shown within the MAC address. An arrow points from the Mask field to an 'Address comparison value (8 bits)' box. Another arrow points from the 'Address_Position_Mask' label to the Mask field. A reference code T0904730-97/d040 is present.](b35ea3e304aad7d350a9902270413930_img.jpg)
+
+Diagram showing the position of a Mask in a MAC address. The MAC address is 6 bytes (48 bits) long, with MSB on the left and LSB on the right. A Mask field is shown within the MAC address. An arrow points from the Mask field to an 'Address comparison value (8 bits)' box. Another arrow points from the 'Address\_Position\_Mask' label to the Mask field. A reference code T0904730-97/d040 is present.
+
+Figure A.31/J.112 – Position of Mask in MAC address
+
+##### A.5.5.4.2 <MAC> Sign-On Response Message (upstream Contention or Ranging)
+
+The <MAC> Sign-On Response Message is sent by the NIU in response to the <MAC> Sign-On Request Message issued by the INA Entity. The NIU shall wait for a random time less than Response\_Collection\_Time\_Window to send this message (see Table A.20).
+
+Table A.20/J.112 – Sign-On Response message structure
+
+|                              | Bits | Bytes | Bit number/Description |
+|------------------------------|------|-------|------------------------|
+| Sign-On_Response_Message() { |      |       |                        |
+| [reserved]                   | 32   | 4     |                        |
+| [reserved]                   | 16   | 2     |                        |
+| Retry_Count                  | 8    | 1     |                        |
+| }                            |      |       |                        |
+
+###### Retry Count
+
+Retry\_Count is an 8-bit unsigned integer that indicates the number of transmissions of the <MAC> Sign-On Response. This field is always included in the response to the <MAC> Sign-On Request.
+
+##### A.5.5.4.3 <MAC> Ranging and Power Calibration Message (singlecast downstream)
+
+The <MAC> RANGING AND POWER CALIBRATION MESSAGE is sent by the INA to the NIU to adjust the power level or time offset the NIU is using for upstream transmission. The format of this message is shown in Table A.21.
+
+**Table A.21/J.112 – Ranging and Power Calibration message structure**
+
+|                                                                   | Bits | Bytes | Bit number/description |
+|-------------------------------------------------------------------|------|-------|------------------------|
+| Ranging_and_Power_Calibration_Message() {                         |      |       |                        |
+| <b>Range_Power_Control_Field</b>                                  | 8    | 1     |                        |
+| <i>reserved</i>                                                   | 5    |       | 7-3:                   |
+| ranging_slot_included                                             | 1    |       | 2: {no, yes}           |
+| time_adjustment_included                                          | 1    |       | 1: {no, yes}           |
+| power_ajustment_included                                          | 1    |       | 0: {no, yes}           |
+| if (range_power_control_field ==<br>time_adjustment_included ) {  |      |       |                        |
+| <b>Time_Offset_Value</b>                                          | (16) | (2)   |                        |
+| }                                                                 |      |       |                        |
+| if (range_power_control_field ==<br>power_adjustment_included ) { |      |       |                        |
+| <b>Power_Control_Setting</b>                                      | (8)  | (1)   |                        |
+| }                                                                 |      |       |                        |
+| if (range power control field ==<br>ranging_slot_included) {      |      |       |                        |
+| <b>Ranging_Slot_Number</b>                                        | (16) | (2)   |                        |
+| }                                                                 |      |       |                        |
+
+###### Range and Power Control Field
+
+`Range_Power_Control_Field` specifies which Range and Power Control parameters are included in the message.
+
+###### Time Adjustment Included
+
+`time_adjustment_included` is a boolean when set, indicates that a relative Time Offset Value is included that the NIU should use to adjust its upstream slot transmit position.
+
+###### Power Adjust Included
+
+`power_adjust_included` is a boolean when set, indicates that a relative Power Control Setting is included in the message.
+
+###### Ranging Slot Included
+
+`Ranging_Slot_Included` is a boolean when set, indicates the calibration slot available. When this bit equals 1, the NIU must send its response on the slot number given by **Ranging Slot Number**. When this bit equals 0, the NIU must respond on a ranging slot as mentioned in Figure A.30.
+
+###### Time Offset Value
+
+`Time_Offset_Value` is a 16-bit short integer representing a relative offset of the upstream transmission timing. A negative value indicates an adjustment forward in time (later). A positive value indicates an adjustment back in time (earlier). The unit of measure is 100 ns (The NIU will adjust approximately its time offset to the closest value indicated by the `Time_Offset_Value` parameter, which implies that no extra clock is needed to adjust to the correct offset).
+
+###### Power Control Setting
+
+`Power_Control_Setting` is an 8-bit signed integer to be used to set the new power level of the NIU. (A positive value represents an increase of the output power level.)
+
+$$\text{New output\_power\_level} = \text{current output\_power\_level} + \text{power\_control\_setting} \times 0.5 \text{ dB}$$
+
+###### Ranging Slot Number
+
+`Ranging_Slot_Number` is a 16-bit unsigned integer that represents the reserved access Slot Number assigned for Ranging the NIU. It shall be assigned by the INA in the reservation area. The INA shall assure that an unassigned slot precedes and follows the ranging slot.
+
+##### A.5.5.4.4 <MAC> Ranging and Power Calibration Response Message (upstream reserved or contention ranging)
+
+The <MAC> RANGING AND POWER CALIBRATION RESPONSE Message is sent by the NIU to the INA in response to the <MAC> RANGING AND POWER CALIBRATION MESSAGE. The format of the message is shown in Table A.22.
+
+Table A.22/J.112 – Ranging and Power Calibration Response message structure
+
+|                                                 | Bits | Bytes | Bit number/Description |
+|-------------------------------------------------|------|-------|------------------------|
+| <code>Ranging_Power_Response_Message() {</code> |      |       |                        |
+| <code>Power_Control_Setting</code>              | 8    | 1     |                        |
+| <code>}</code>                                  |      |       |                        |
+
+###### Power Control Setting
+
+`Power_Control_Setting` is an 8-bit signed integer defined as a copy of the power control setting parameter received from INA.
+
+##### A.5.5.4.5 <MAC> Initialization Complete Message (singlecast downstream)
+
+This message has no message body. It indicates the end of the MAC Sign-On and Provisioning procedure.
+
+#### A.5.5.5 Default Connection Establishment
+
+Once a NIU has completed the Calibration State, it shall enter the Connection State. A low bit rate permanent connection is assigned to a NIU by the INA. After the initial calibration procedure, the INA provides a Default Connection to the NIU that the NIU shall utilize to communicate to the network. The message flow for such Connection Establishment is shown below (see Figure A.32):
+
+- 1) After Initialization, Provisioning and Sign-On procedures are complete, the INA shall assign a default upstream and downstream connection to the NIU. This connection can be assigned on any of the upstream channels except the upstream service channel ranging area. The INA shall assign the default connection by sending the <MAC> **Connect Message** to the NIU. This message shall contain the upstream connection parameters and downstream frequency on which the default connection is to reside.
+- 2) The NIU, upon receiving the <MAC> **Connect Message** shall tune to the required upstream and downstream frequencies and send the <MAC> **Connect Response Message** confirming receipt of the message.
+- 3) Upon receipt of the <MAC> **Connect Response Message**, the INA shall confirm the new connection to proceed by sending the <MAC> **Connect Confirm Message**.
+
+![Diagram showing connection signalling between INA and NIU/STB. Three messages are shown: <MAC> Connect Message (INA to NIU/STB), <MAC> Connect Response (NIU/STB to INA), and <MAC> Connect Confirm (INA to NIU/STB).](b20942bb14022381a243971ab9790dd9_img.jpg)
+
+```
+
+    INA                                     NIU/STB
+      |                                     |
+      |-----<MAC> Connect Message----->|
+      |                                     |
+      |-----<MAC> Connect Response----->|
+      |                                     |
+      |-----<MAC> Connect Confirm----->|
+  
+```
+
+T0904740-97/d041
+
+Diagram showing connection signalling between INA and NIU/STB. Three messages are shown:  Connect Message (INA to NIU/STB),  Connect Response (NIU/STB to INA), and  Connect Confirm (INA to NIU/STB).
+
+Figure A.32/J.112 – Connection signalling
+
+##### A.5.5.5.1 <MAC> Connect Message (singlecast downstream)
+
+See Table A.23.
+
+Table A.23/J.112 – Connect message structure
+
+|                                                         | Bits | Bytes | Numéro number/<br>Description |
+|---------------------------------------------------------|------|-------|-------------------------------|
+| Connect_Message () {                                    |      |       |                               |
+| <b>Connection_ID</b>                                    | 32   | 4     |                               |
+| <b>Session_Number</b>                                   | 32   | 4     |                               |
+| <b>Resource_Number</b>                                  | 16   | 2     |                               |
+| <b>Connection_Control_Field</b>                         | 8    | 1     |                               |
+| DS_ATM_CBD_Included                                     | 1    |       | 7: {no, yes}                  |
+| DS_MPEG_CBD_Included                                    | 1    |       | 6: {no, yes}                  |
+| US_ATM_CBD_Included                                     | 1    |       | 5: {no, yes}                  |
+| Upstream_Channel_Number                                 | 3    |       | 4-2                           |
+| Slot_List_Included                                      | 1    |       | 1: {no, yes}                  |
+| Cyclic_Assignment                                       | 1    |       | 0: {no, yes}                  |
+| <b>Frame_Length</b>                                     | (16) | (2)   |                               |
+| <b>Maximum_Contention_Access_Message_Length</b>         | (8)  | (1)   |                               |
+| <b>Maximum_Reservation_Access_Message_Length</b>        | (8)  | (1)   |                               |
+| if (Connection_Control_Field && DS_ATM_CBD_Included) {  |      |       |                               |
+| <b>Downstream_ATM_CBD()</b>                             | 64   | 8     |                               |
+| }                                                       |      |       |                               |
+| if (Connection_Control_Field && DS_MPEG_CBD_Included) { |      |       |                               |
+| <b>Downstream_MPEG_CBD()</b>                            | 48   | 6     |                               |
+| }                                                       |      |       |                               |
+| if (Connection_Control_Field && US_ATM_CBD_Included) {  |      |       |                               |
+| <b>Upstream_ATM_CBD()</b>                               | 64   | 8     |                               |
+| }                                                       |      |       |                               |
+| if (Connection_Control_Field && Slot_List_Included) {   |      |       |                               |
+| <b>Number_Slots_Defined</b>                             | 8    | 1     |                               |
+| for (i=0; i<Number_Slots_Assigned; i++) {               |      |       |                               |
+| <b>Slot_Number</b>                                      | (16) | (2)   |                               |
+| }                                                       |      |       |                               |
+| }                                                       |      |       |                               |
+| if (MAC_Control_Params == cyclic_Assignment){           |      |       | Fixed Rate Access             |
+| <b>Fixedrate_Start</b>                                  | (16) | (2)   |                               |
+| <b>Fixedrate_Dist</b>                                   | (16) | (2)   |                               |
+| <b>Fixedrate_End</b>                                    | (16) | (2)   |                               |
+| }                                                       |      |       |                               |
+| }}                                                      |      |       |                               |
+
+###### Connection ID
+
+`Connection_ID` is a 32-bit unsigned integer representing a connection Identifier for the NIU Dynamic Connection.
+
+###### Session Number
+
+`Session_Number` is a 32-bit unsigned integer representing the Session that the connection parameters are associated. This parameter is not used by this specification.
+
+###### Resource Number
+
+`Resource_Number` is a 16-bit unsigned integer providing a unique number to the resource defined in the message. This parameter is not used by this specification.
+
+###### Connection Control Field
+
+`DS_ATM_CBD_Included` is a boolean that indicates that the Downstream ATM Descriptor is included in the message.
+
+`DS_MPEG_CBD_Included` is a boolean that indicates that the Downstream MPEG Descriptor is included in the message.
+
+`US_ATM_CBD_Included` is a boolean that indicates that the Upstream ATM Descriptor is included in the message.
+
+`Upstream_Channel_Number` is a 3-bit unsigned integer that provides an identifier for the upstream channel. This parameter is not used in this specification.
+
+`Slot_List_Included` is a boolean that indicates that the Slot List is included in the message.
+
+`Cyclic_Assignment` is a boolean that indicates Cyclic Assignment.
+
+###### Frame Length
+
+`Frame_length` – This 16-bit unsigned number represents the number of successive slots in the fixed rate access region associated with each fixed rate slot assignment. In the `slot_list` method of allocating slots it represents the number of successive slots associated with each element in the list. In the cyclic method of allocating slots it represents the number of successive slots associated with the `Fixedrate_Start_slot` and those which are multiples of `Fixedrate_Distance` from the `Fixedrate_Start_slot` within the Fixed rate access region.
+
+###### Maximum Contention Access Message Length
+
+`Maximum_contention_access_message_length` is an 8-bit number representing the maximum length of a message in ATM sized cells that may be transmitted using contention access. Any message greater than this should use reservation access.
+
+###### Maximum Reservation Access Message Length
+
+`Maximum_reservation_access_message_length` is an 8-bit number representing the maximum length of a message in ATM sized cells that may be transmitted using a single reservation access. Any message greater than this should be transmitted by making multiple reservation requests.
+
+###### Downstream ATM Connection Block Descriptor
+
+See Table A.24.
+
+Table A.24/J.112 – ATM Connection Block Descriptor substructure
+
+|                                     | Bits | Bytes | Bit number/<br>Description |
+|-------------------------------------|------|-------|----------------------------|
+| <code>Downstream_ATM_CBD() {</code> |      |       |                            |
+| <code>Downstream_Frequency</code>   | 32   | 4     |                            |
+| <code>Downstream_VPI</code>         | 8    | 1     |                            |
+| <code>Downstream_VCI</code>         | 16   | 2     |                            |
+| <code>Downstream_Type</code>        | 8    | 1     |                            |
+| <code>}</code>                      |      |       |                            |
+
+###### *Downstream Frequency*
+
+`Downstream_Frequency` is a 32-bit unsigned integer representing the Frequency where the connection resides. The unit of measure is in Hz.
+
+###### *Downstream Virtual Path Identifier*
+
+`Downstream_VPI` is an 8-bit unsigned integer representing the ATM Virtual Path Identifier that is used for downstream transmission over the Dynamic Connection.
+
+###### *Downstream Virtual Channel Identifier*
+
+`Downstream_VCI` is a 16-bit unsigned integer representing the ATM Virtual Channel Identifier that is used for downstream transmission over the Dynamic Connection.
+
+###### *DownStream\_Type*
+
+`DownStream_Type` is an 8-bit enumerated type indicating the modulation format for the down stream connection. { reserved, QPSK\_1.544, QPSK\_3.088, 3..255 reserved }.
+
+###### **Downstream MPEG Connection Block Descriptor**
+
+See Table A.25.
+
+**Table A.25/J.112 – Downstream\_MPEG\_CBD substructure**
+
+|                                      | Bits | Bytes | Bit number/<br>Description |
+|--------------------------------------|------|-------|----------------------------|
+| <code>Downstream_MPEG_CBD() {</code> |      |       |                            |
+| <code>Downstream_Frequency</code>    | 32   | 4     |                            |
+| <code>Program_Number</code>          | 16   | 2     |                            |
+| <code>}</code>                       |      |       |                            |
+
+###### *Downstream Frequency*
+
+`Downstream_Frequency` is a 32-bit unsigned integer representing the Frequency where the connection resides. The unit of measure is in Hz.
+
+###### *Program Number*
+
+`Program_Number` is a 16-bit unsigned integer uniquely referencing the downstream virtual connection assignment (PID of the MPEG-2 program).
+
+###### **Upstream ATM Connection Block Descriptor**
+
+See Table A.26.
+
+**Table A.26/J.112 – Upstream\_CBD substructure**
+
+|                                   | Bits | Bytes | Bit number/<br>Description |
+|-----------------------------------|------|-------|----------------------------|
+| <code>Upstream_ATM_CBD() {</code> |      |       |                            |
+| <code>Upstream_Frequency</code>   | 32   | 4     |                            |
+| <code>Upstream_VPI</code>         | 8    | 1     |                            |
+| <code>Upstream_VCI</code>         | 16   | 2     |                            |
+| <code>MAC_Flag_Set</code>         | 5    | 1     | 7:3                        |
+| <code>Upstream_Rate</code>        | 3    |       | 2:0                        |
+| <code>}</code>                    |      |       |                            |
+
+###### *Upstream Frequency*
+
+*Upstream\_Frequency* is a 32-bit unsigned integer representing the channel on assigned to the connection. The unit of measure is in Hz.
+
+###### *Upstream Virtual Path Identifier*
+
+*Upstream\_VPI* is an 8-bit unsigned integer representing the ATM Virtual Path Identifier that is used for upstream transmission over the Dynamic Connection.
+
+###### *Upstream Virtual Channel Identifier*
+
+*Upstream\_VCI* is a 16-bit unsigned integer representing the ATM Virtual Channel Identifier that is used for upstream transmission over the Dynamic Connection.
+
+###### *MAC\_Flag\_Set*
+
+*MAC\_Flag\_Set* is a 5-bit field representing the MAC Flag set assigned to the connection. In the OOB downstream SL-ESF frame payload structure, each set of three bytes, denoted by Rxa-Rxc, comprise a flag set. These eight flag sets are assigned the numbers 1-8. In the IB downstream timing, the 16-flag sets are assigned the numbers 1-16. In the case of a 3.088 Mbit/s upstream channel, two successive flag sets are required to define a 3-ms period. In this case, this parameter represents the first of two successively assigned flag sets. In the case of a 3.088 Mbit/s OOB downstream, two successive SL-ESF frames define the 3-ms interval. The Rxa-Rxc bytes of the first frame represent flag sets 1-8 while the Rxa-Rxc bytes of the second frame represent flag sets 9-16.
+
+###### *Upstream\_Rate*
+
+*Upstream\_Rate* is a 3-bit enumerated type indicating the data rate for the upstream connection. { Upstream\_256K, Upstream\_1.544M, Upstream\_3.088M, 3..7 reserved }
+
+###### **Number of Slots Defined**
+
+*Number\_Slots\_Defined* is an 8-bit unsigned integer that represents the number of slot assignments contained in the message. The unit of measure is slots.
+
+###### **Slot Number**
+
+*Slot\_Number* is a 16-bit unsigned integer that represents the Fixed rate based Slot Number assigned to the NIU.
+
+###### **Fixed rate Start**
+
+*Fixedrate\_Start* – This 16-bit unsigned number represents the starting slot within the fixed rate access region that is assigned to the NIU. The NIU may use the next *Frame\_length* slots of the fixed rate access regions.
+
+###### **Fixed rate Distance**
+
+*Fixedrate\_Distance* – This 16-bit unsigned number represents the distance in slots between additional slots assigned to the NIU. The NIU is assigned all slots that are a multiple of *Fixedrate\_Distance* from the *Fixedrate\_Start\_slot* which do not exceed *Fixedrate\_End\_slot*. The NIU may use the next *Frame\_length* slots. of the fixed rate access regions from each of these additional slots.
+
+###### **Fixed rate End**
+
+*Fixedrate\_End* – This 16-bit unsigned number indicates the last slot that may be used for fixed rate access. The slots assigned to the NIU, as determined by using the *Fixedrate\_Start\_slot*, the *Fixedrate\_Distance* and the *Frame\_length*, cannot exceed this number.
+
+##### **A.5.5.5.2 <MAC> Connect Response (upstream contention, reserved or contention access)**
+
+The <MAC> CONNECT RESPONSE MESSAGE is sent to the INA from the NIU in response to the <MAC> CONNECT MESSAGE. The message shall be transmitted on the upstream frequency specified in the <MAC> CONNECT MESSAGE (see Table A.27).
+
+**Table A.27/J.112 – Connect response message structure**
+
+|                      | Bits | Bytes | Bit number/<br>Description |
+|----------------------|------|-------|----------------------------|
+| Connect_Response() { |      |       |                            |
+| <b>Connection_ID</b> | 32   | 4     |                            |
+| }                    |      |       |                            |
+
+###### **Connection ID**
+
+Connection\_ID is a 32-bit unsigned integer representing a global connection Identifier for the NIU Dynamic Connection.
+
+##### **A.5.5.5.3 <MAC> Connect Confirm (singlecast downstream)**
+
+The <MAC> Connect Confirm message is sent from the INA to the NIU (see Table A.28).
+
+**Table A.28/J.112 – Connect Confirm message structure**
+
+|                      | Bits | Bytes | Bit number/<br>Description |
+|----------------------|------|-------|----------------------------|
+| Connect_Confirm() {  |      |       |                            |
+| <b>Connection_ID</b> | 32   | 4     |                            |
+| }                    |      |       |                            |
+
+###### **Connection ID**
+
+Connection\_ID is a 32-bit unsigned integer representing a global connection Identifier for the NIU Dynamic Connection.
+
+#### **A.5.5.6 Data connections**
+
+A connection is initiated by the INA using the <MAC> Connect Message explained in A.5.5.5.1. This message is either used to immediately assign time slots for a fixed rate connection or just to assign a connection ID and related parameters without time slot assignment. In particular, for reservation or contention access, no time slots are assigned in the Connect Message, but the connection ID shall be used in requests for slots by the NIU.
+
+##### **Connection Assignment**
+
+The INA can assign other connections by using the <MAC> **Connect message** described previously. The NIU cannot request a connection, it must be initiated by higher layers.
+
+##### **Connection Release**
+
+This subclause defines the MAC signalling requirements for connection release. Figure A.33 displays the signalling flow for releasing a connection. The NIU cannot release a connection, this must be initiated by higher layers. This message is thus initiated by the INA only:
+
+- 1) Upon receiving the <MAC> **Release Message** from the INA, the NIU shall tear down the upstream connection established for the specified Connection\_ID.
+- 2) Upon teardown of the upstream connection, the NIU shall send the <MAC> **Release Response Message** on the upstream channel previously assigned for that connection.
+
+![Sequence diagram showing connection release signalling between NRC and NIU/STB. The NRC sends a <MAC> Release Message to the NIU/STB, and the NIU/STB responds with a <MAC> Release Response. The diagram is labeled T0904750-97/d042.](32d36dfe7dc75b7c63f8edf0f28e4009_img.jpg)
+
+```
+
+sequenceDiagram
+    participant NRC
+    participant NIU/STB
+    Note right of NIU/STB: T0904750-97/d042
+    NRC->>NIU/STB: <MAC> Release Message
+    NIU/STB-->>NRC: <MAC> Release Response
+  
+```
+
+Sequence diagram showing connection release signalling between NRC and NIU/STB. The NRC sends a  Release Message to the NIU/STB, and the NIU/STB responds with a  Release Response. The diagram is labeled T0904750-97/d042.
+
+Figure A.33/J.112 – Connection release signalling
+
+##### **<MAC> Release Message (singlecast downstream)**
+
+The **<MAC> Release Message** is sent from the INA to the NIU to terminate a previously established connection (see Table A.29).
+
+Table A.29/J.112 – Release message structure
+
+|                                           | Bits | Bytes | Bit number/<br>Description |
+|-------------------------------------------|------|-------|----------------------------|
+| Release_Message() {                       |      |       |                            |
+| <b>Number_of_Connections</b>              | 8    | 1     |                            |
+| for (i=0; i<Number_of_Connections; i++) { |      |       |                            |
+| <b>Connection_ID</b>                      | 32   | 4     |                            |
+| }<br>}                                    |      |       |                            |
+
+###### *Connection ID*
+
+*Connection\_ID* is a 32-bit unsigned integer representing a global connection Identifier for the NIU Dynamic Connection.
+
+##### **<MAC> Release Response (upstream contention, reserved or contention)**
+
+The **<MAC> RELEASE RESPONSE MESSAGE** is sent by the NIU to the INA to acknowledge the release of a connection. The format of the message is shown in Table A.30.
+
+Table A.30/J.112 – Release Response message structure
+
+|                               | Bits | Bytes | Bit number/<br>Description |
+|-------------------------------|------|-------|----------------------------|
+| Release_Response_Message () { |      |       |                            |
+| <b>Connection_ID</b>          | 32   | 4     |                            |
+| }                             |      |       |                            |
+
+###### *Connection ID*
+
+*Connection\_ID* is a 32-bit unsigned integer representing the global connection Identifier used by the NIU for this connection.
+
+##### **A.5.5.6.1 Fixed rate access**
+
+Fixed rate access is provided by the INA using the **<MAC> Connect Message**.
+
+##### A.5.5.6.2 Contention based access
+
+The NIU shall use contention based slots specified by the slot boundary definition fields (Rx) to transmit contention based messages (see A.5.3). The format of contention based MAC messages is described by the MAC message format (see A.5.5.2.3).
+
+##### A.5.5.6.3 Reservation access
+
+This subclause defines the MAC signalling requirements for reservation access. Figure A.34 displays the signalling flow for reserving an access:
+
+- 1) The NIU shall wait for a <MAC> Reservation ID Assignment Message from the INA before it can request reservation access.
+- 2) At any time when needed after receiving the reservation ID, the NIU can request a certain number of slots to the INA using the <MAC> Reservation Request Message.
+- 3) The INA shall respond to that message using the <MAC> Reservation Grant Message.
+- 4) If the NIU has not received the <MAC> Reservation Grant Message before the Grant\_Protocol\_Timeout, it shall send a <MAC> Reservation Status Request to the INA. This leads back to 3).
+
+![Sequence diagram showing reservation access signalling between INA and NIU. The sequence is: INA sends <MAC> Reservation ID Assignment Message to NIU; NIU sends <MAC> Reservation ID Response Message to INA; NIU sends <MAC> Reservation Request Message to INA; INA sends <MAC> Reservation Grant Message to NIU. The diagram is labeled T0904760-97/d043.](cf018d13814389b0bd7f94a2f9bb812a_img.jpg)
+
+```
+
+sequenceDiagram
+    participant INA
+    participant NIU
+    Note right of INA: INA
+    Note left of NIU: NIU
+    INA->>NIU: <MAC> Reservation ID Assignment Message
+    NIU-->>INA: <MAC> Reservation ID Response Message
+    NIU->>INA: <MAC> Reservation Request Message
+    INA->>NIU: <MAC> Reservation Grant Message
+    Note right of INA: T0904760-97/d043
+  
+```
+
+Sequence diagram showing reservation access signalling between INA and NIU. The sequence is: INA sends  Reservation ID Assignment Message to NIU; NIU sends  Reservation ID Response Message to INA; NIU sends  Reservation Request Message to INA; INA sends  Reservation Grant Message to NIU. The diagram is labeled T0904760-97/d043.
+
+Figure A.34/J.112 – Reservation access signalling
+
+##### <MAC> Reservation ID Assignment Message (singlecast downstream)
+
+The <MAC> Reservation ID Assignment Message is used to assign the NIU a Reservation\_ID. The NIU identifies its entry in the Reservation\_grant\_message by comparing the Reservation\_ID assigned to it by the Reservation\_ID\_assignment\_message and the entries in the Reservation\_Grant\_message.
+
+The format of the message is given in Table A.31.
+
+Table A.31/J.112 – Reservation ID assignment message structure
+
+|                                        | Bits | Bytes | Bit number/<br>Description |
+|----------------------------------------|------|-------|----------------------------|
+| Reservation_ID_assignment_Message () { |      |       |                            |
+| Connection_ID                          | 32   | 4     |                            |
+| Reservation_ID                         | 16   | 2     |                            |
+| Grant_protocol_timeout                 | 16   | 2     |                            |
+| }                                      |      |       |                            |
+
+###### *Connection ID*
+
+`Connection_ID` is a 32-bit unsigned integer representing a global connection identifier for the NIU Dynamic Connection.
+
+###### *Reservation\_ID*
+
+`Reservation_ID` is a 16-bit unsigned number representing a locally assigned identifier for the connection. This is used as a short identifier by the NIU to identify the appropriate `Reservation_Grant_Messages`.
+
+###### *Grant\_protocol\_timeout*
+
+`Grant_protocol_timeout` is a 16-bit unsigned number representing the time in milliseconds that the NIU should wait before verifying the status of pending grants. This parameter specifies the time that the NIU should wait after receiving the last <MAC> `Reservation_grant_message`, with an entry addressed to the NIU, before initiating a reservation status request. If the NIU has pending grants and the timeout occurs, it should send the `Reservation_status_request` message to the INA. The INA will respond with the `Reservation_grant_message` (probably without granting any slots) to inform the NIU of any remaining slots left to be granted. This allows the NIU to correct any problems, should they exist, such as issuing an additional request for slots or waiting patiently for additional grants.
+
+###### **<MAC> Reservation ID Response Message (upstream, contention or reserved access)**
+
+The <MAC> Reservation ID Response Message is used to acknowledge the receipt of the <MAC> `Reservation_ID_Assignment` message.
+
+The format of the message is given below.
+
+|                                                   | Bits | Bytes | Bit number/<br>Description |
+|---------------------------------------------------|------|-------|----------------------------|
+| <code>Reservation_ID_Response_Message () {</code> |      |       |                            |
+| <b><code>Connection_ID</code></b>                 | 32   | 4     |                            |
+| <b><code>Reservation_ID</code></b>                | 16   | 2     |                            |
+| <code>}</code>                                    |      |       |                            |
+
+###### **Connection ID**
+
+`Connection_ID` is a 32-bit unsigned integer representing a global connection identifier for the NIU/STB Dynamic Connection.
+
+###### **Reservation\_ID**
+
+`Reservation_ID` is a 16-bit unsigned number representing a locally assigned identifier for the connection. This is used as a short identifier by the NIU/STB to identify the appropriate `Reservation_Grant_Messages`.
+
+##### **<MAC> Reservation Request Message (upstream contention, contention or reserved)**
+
+See Table A.32.
+
+**Table A.32/J.112 – Reservation Request message structure**
+
+|                                                    | Bits | Bytes | Bit number/<br>Description |
+|----------------------------------------------------|------|-------|----------------------------|
+| <code>Reservation_Request_message () {</code>      |      |       |                            |
+| <b><code>Reservation_ID</code></b>                 | 16   | 2     |                            |
+| <b><code>Reservation_request_slot_count</code></b> | 8    | 1     |                            |
+| <code>}</code>                                     |      |       |                            |
+
+This message is sent from the NIU to the INA.
+
+###### *Reservation\_ID*
+
+*Reservation\_ID* is a 16-bit unsigned number representing a locally assigned identifier for the connection. This is used as a short identifier by the NIU to identify the appropriate *Reservation\_Grant\_Messages*.
+
+###### *Reservation Request Slot Count*
+
+*Reservation\_request\_slot\_count* is an 8-bit unsigned number representing the number of slots requested by the NIU. This is the number of sequential slots that will be allocated in the reservation region of the upstream channel. The INA will respond with the *Reservation\_Grant* message granting the request.
+
+##### **<MAC> Reservation Grant Message (broadcast downstream)**
+
+The <MAC> RESERVATION GRANT MESSAGE is used to indicate to the NIU which slots have been allocated in response to the *Reservation Request* message. The NIU identifies its entry in the *Reservation\_grant\_message* by comparing the *Reservation\_ID* assigned to it by the *Reservation\_ID\_assignment\_message* and the entries in the *Reservation\_Grant\_message*.
+
+The format of the message is given in Table A.33.
+
+**Table A.33/J.112 – Reservation Grant message structure**
+
+|                                       | Bits | Bytes | Bit number/<br>Description |
+|---------------------------------------|------|-------|----------------------------|
+| <i>Reservation_grant_message</i> () { |      |       |                            |
+| <b>Reference_slot</b>                 | 16   | 2     |                            |
+| <b>Number_grants</b>                  | 8    | 1     |                            |
+| for (I=1; I<=Number_grants; I++){     |      |       |                            |
+| <b>Reservation_ID</b>                 | 16   | 2     |                            |
+|                                       |      | 2     |                            |
+| <b>Grant_Slot_count</b>               | 4    |       | 15-12                      |
+| <b>Remaining_slot_count</b>           | 5    |       | 11-7                       |
+| <b>Grant_control</b>                  | 2    |       | 6-5                        |
+| <b>Grant_slot_offset</b>              | 5    |       | 4-0                        |
+| }                                     |      |       |                            |
+| }                                     |      |       |                            |
+
+###### *Reference\_slot*
+
+*Reference\_slot* is a 16-bit unsigned number indicating the reference point for the remaining parameters of this message. This represents a physical slot of the upstream channel. Since the upstream and downstream slots are not aligned, the INA shall send this message in a downstream slot such that it is received by the NIU before the *Reference\_slot* exists on the upstream channel.
+
+###### *Number\_grants*
+
+*Number\_grants* is an 8-bit unsigned number representing the number of grants contained within this message. This can either correspond to grants for different NIUs, or to different connection\_IDs for the same NIU.
+
+###### *Reservation\_ID*
+
+*Reservation\_ID* is a 16-bit unsigned number representing a locally assigned identifier for the connection. This is used as a short identifier by the NIU to identify the appropriate *Reservation\_Grant\_Messages*.
+
+###### *Grant\_slot\_count*
+
+*Grant\_slot\_count* is a 4-bit unsigned number representing the number of sequential slots currently granted for the upstream burst. Upon receipt of this message, the NIU is assigned *Grant\_slot\_count* sequential slots in the reservation access region of the upstream channel starting at the position indicated by the *Reference\_slot* and *Grant\_slot\_offset* values (jumps are needed in the case where the number of slots granted exceeds the length of the reservation access region). A value of zero indicates that no slots are being granted. This would typically be the case in a response to a *Reservation\_status\_request* message.
+
+###### *Remaining\_slot\_count*
+
+*Remaining\_slot\_count* is a 5-bit unsigned number representing the remaining slots to be granted by the INA with subsequent grant messages. A value of 0x1f indicates that 31 or more slots will be made available in the future. A value of 0x0 indicates that no additional slots will be granted in the future and that the slots granted in this message represent the only remaining slots available for the connection. The NIU should monitor this count to determine if sufficient slots remain to satisfy current needs. Should additional slots be required because of lost grant messages or additional demand, additional slots should be requested using the *Reservation\_request\_message*. Additional *Reservation\_request\_messages* shall be sent only when the *Remaining\_slot\_count* is less than 15. To minimize contention on the upstream channel, the *Reservation\_request\_message* may be sent in one of the slots granted by the *Reservation\_grant\_message*.
+
+###### *Grant\_Control*
+
+*Grant\_Control* is a 2-bit unsigned number coded as 0 (reserved for future use).
+
+###### *Grant\_slot\_offset*
+
+*Grant\_slot\_offset* is a 5-bit unsigned number representing the starting slot to be used for the upstream burst. This number is added to the *Reference\_slot* to determine the actual physical slot. Upon receipt of this message, the NIU is assigned *Grant\_slot\_count* sequential slots in the reservation access region of the upstream channel.
+
+##### **<MAC> Reservation Status Request (upstream contention, contention or reserved)**
+
+The <MAC> RESERVATION STATUS REQUEST Message is used to determine the status of the outstanding grants to be assigned by the INA. This message is only sent after the Grant protocol time-out is exceeded. The INA will respond with the *Reservation\_grant\_message* (possibly without granting any slots) to inform the NIU of any remaining slots left to be granted. This allows the NIU to correct any problems, should they exist, such as issuing an additional request for slots or waiting patiently for additional grants.
+
+The format of the message is given in Table A.34.
+
+**Table A.34/J.112 – Reservation status request message structure**
+
+|                                                | Bits | Bytes | Bit number/<br>Description |
+|------------------------------------------------|------|-------|----------------------------|
+| <i>Reservation_Status_Request_Message () {</i> |      |       |                            |
+| <b>    <i>Reservation_ID</i></b>               | 16   | 2     |                            |
+| <b>    <i>Remaining_request_slot_count</i></b> | 8    | 1     |                            |
+| <i>}</i>                                       |      |       |                            |
+
+###### *Reservation\_ID*
+
+*Reservation\_ID* is a 16-bit unsigned number representing a locally assigned identifier for the connection. This is used as a short identifier by the NIU to identify the appropriate *Reservation\_Grant\_Messages*.
+
+###### *Remaining\_request\_slot\_count*
+
+*Remaining\_request\_slot\_count* is an 8-bit unsigned number representing the number of slots that the NIU is expecting to be granted.
+
+#### A.5.5.7 MAC Link Management
+
+The MAC Link Management tasks provide continuous monitoring and optimization of upstream resources. These functions include:
+
+- Power and Timing Management;
+- Fixed rate Allocation Management;
+- Channel Error Management.
+
+##### A.5.5.7.1 Power and Timing Management
+
+Power and Timing Management shall provide continuous monitoring of upstream transmission from the NIU. The <MAC> **Ranging and Power Calibration Message** is used to maintain a NIU within predefined thresholds of power and time.
+
+The Upstream Burst Demodulator shall continuously monitor the upstream burst transmissions from an NIU. Upon detection of an NIU outside the predefined range, the INA shall send the <MAC> **Ranging and Power Calibration Message** to the NIU.
+
+##### A.5.5.7.2 TDMA Allocation Management
+
+To ensure optimum assignment of TDMA resources, the INA shall ensure the upstream allocation of TDMA resources for various connections remain intact when allocating resources to a new connection. However, in the event that reconfiguration is required to minimize fragmentation of resources, then the INA shall dynamically reconfigure the upstream TDMA assignments to a NIU or group of NIUs. The <MAC> **Reprovision Message** is utilized to change previously established connection parameters.
+
+##### <MAC> Reprovision Message (singlecast downstream)
+
+The <MAC> REPROVISION MESSAGE is sent by the INA to the NIU to reassign upstream resources (maintaining the originally requested QOS parameters at the establishment of the connection.) This message is intended for Fixed rate based channel maintenance by the INA to redistribute or reassign resources allocated to a NIU (see Table A.35).
+
+**Table A.35/J.112 – Reprovision message structure**
+
+|                                                                     | Bits | Bytes | Bit number/<br>Description |
+|---------------------------------------------------------------------|------|-------|----------------------------|
+| Reprovision_Message () {                                            |      |       |                            |
+| <b>Reprovision_Control_Field</b>                                    | 8    | 1     |                            |
+| <i>Reserved</i>                                                     | 2    |       | 7-6                        |
+| New_Downstream_IB_Frequency                                         | 1    |       | 5: {no, yes}               |
+| New_Downstream_OOB_Frequency                                        | 1    |       | 4: {no, yes}               |
+| New_Upstream_Frequency_Included                                     | 1    |       | 3: {no, yes}               |
+| New_Frame_Length_Included                                           | 1    |       | 2: {no, yes}               |
+| New_Cyclical_Assignment_Included                                    | 1    |       | 1: {no, yes}               |
+| New_Slot_List_Included                                              | 1    |       | 0: {no, yes}               |
+| if (Reprovision_Control_Field & =<br>New_Downstream_IB_Frequency) { |      |       |                            |
+
+Table A.35/J.112 – Reprovision message structure (end)
+
+|                                                                                                                    | Bits | Bytes | Bit number/<br>Description   |
+|--------------------------------------------------------------------------------------------------------------------|------|-------|------------------------------|
+| <b>New_Downstream_IB_Frequency }</b>                                                                               | (32) | (4)   |                              |
+| <i>if (Reprovision_Control_Field &amp; =<br/>New_Downstream_OOB_Frequency) {</i>                                   |      |       |                              |
+| <b>New_Downstream_OOB_Frequency</b>                                                                                | (32) | (4)   |                              |
+| <b>DownStream_Type }</b>                                                                                           | 8    | 1     |                              |
+| <i>if (Reprovision_Control_Field &amp; =<br/>New_Frequency_Included) {</i>                                         |      |       |                              |
+| <b>New_Upstream_Frequency</b>                                                                                      | (32) | (4)   |                              |
+| <b>New Upstream Parameters</b>                                                                                     |      | (2)   |                              |
+| New_Upstream_Channel_Number                                                                                        | 3    |       | 7:5                          |
+| reserved                                                                                                           | 2    |       | 4:3                          |
+| Upstream_Rate                                                                                                      | 3    |       | 2:0:enum                     |
+| MAC_Flag_Set                                                                                                       | 5    |       | 7:3                          |
+| Reserved}                                                                                                          | 3    |       | 2:0                          |
+| <i>if (Connection_Control_Field &amp; =<br/>New_Frame_Length_Included) {</i>                                       |      |       |                              |
+| <b>New_Frame_Length}</b>                                                                                           | (16) | (2)   | 9:0:<br>Unsigned             |
+| <i>if (Reprovision_Control_Field &amp; =<br/>New_Slot_List_Included   <br/>New_Cyclical_Assignment_Included) {</i> |      |       |                              |
+| <b>Number_of_Connections</b>                                                                                       | (8)  | (1)   |                              |
+| <i>for(i=0;i&lt;Number_of_Connections;i++) {</i>                                                                   |      |       |                              |
+| <b>Connection_ID</b>                                                                                               | (32) | (1)   |                              |
+| <i>if (Reprovision_Control_Field &amp; =<br/>new_slot_list_included) {</i>                                         |      |       | <b>Fixed Rate<br/>Access</b> |
+| <b>Number_Slots_Defined</b>                                                                                        | (8)  | (1)   |                              |
+| <i>for(i=0;i&lt;Number_Slots_Assigned;i++) {</i>                                                                   |      |       |                              |
+| <b>Slot_Number</b>                                                                                                 | (16) | (2)   |                              |
+| <i>}}</i>                                                                                                          |      |       |                              |
+| <i>if (Reprovision_Control_Field ==<br/>new_cyclic_Assignment_included) {</i>                                      |      |       | <b>Fixed Rate<br/>Access</b> |
+| <b>Fixedrate_Start</b>                                                                                             | (16) | (2)   |                              |
+| <b>Fixedrate_Dist</b>                                                                                              | (16) | (2)   |                              |
+| <b>Fixedrate_End</b>                                                                                               | (16) | (2)   |                              |
+| <i>}}}</i>                                                                                                         |      |       |                              |
+
+###### *Reprovision Control Field*
+
+`Reprovision_Control_Field` specifies what modifications to upstream resources are included.
+
+###### *New Downstream OOB Frequency*
+
+`New_Upstream_OOB_Frequency` is a boolean that indicates that a new downstream OOB frequency is specified in the message.
+
+###### *New Downstream IB Frequency*
+
+`New_Upstream_IB_Frequency` is a boolean that indicates that a new downstream IB frequency is specified in the message.
+
+###### *New Upstream Frequency Included*
+
+`New_Upstream_Frequency_Included` is a boolean that indicates that a new upstream frequency is specified in the message.
+
+###### *New Frame Length Included*
+
+`New_Frame_Length_Included` is a boolean that indicates that a new upstream frame is specified in the message.
+
+###### *New Slot List Included*
+
+`New_Slot_List_Included` is a boolean that indicates that a new slot list is specified in the message.
+
+###### *New Cyclical Assignment Included*
+
+`New_Cyclical_Assignment_Included` is a boolean that indicates that a new cyclical assignment is specified in the message.
+
+###### *New Downstream IB Frequency*
+
+`New_Downstream_IB_Frequency` is a 32-bit unsigned integer representing the reassigned downstream IB carrier center frequency. The unit of measure is Hz.
+
+###### *New Downstream OOB Frequency*
+
+`New_Downstream_OOB_Frequency` is a 32-bit unsigned integer representing the reassigned downstream OOB carrier center frequency. The unit of measure is Hz.
+
+`DownStream_Type` is an 8-bit enumerated type indicating the modulation format for the down stream connection.  
+{ reserved, QPSK\_1.544, QPSK\_3.088, 3..255 reserved }
+
+###### *New Upstream Frequency*
+
+`New_Upstream_Frequency` is a 32-bit unsigned integer representing the reassigned upstream carrier center frequency. The unit of measure is Hz.
+
+`UpstreamStream_Rate` is a 3-bit enumerated type indicating the data rate for the upstream connection.  
+{ Upstream\_256K, Upstream\_1.544M, Upstream\_3.088M, 3..7 reserved }
+
+`MAC_Flag_Set` is a 5-bit field representing the MAC Flag set assigned to the connection. In the OOB downstream timing, the eight sets of flags are assigned the numbers 1-8. In the IB downstream timing, the 16 sets of flags are assigned the numbers 1-16. In the case of a 3.088 Mbit upstream channel, this parameter represents the first of two successively assigned flag sets.
+
+###### *New Frame Length*
+
+`New_Frame_Length` is a 16-bit unsigned integer representing the size of the reassigned upstream Fixed rate based frame. The unit of measure is in slots.
+
+###### *Number of Slots Defined*
+
+`Number_Slots_Defined` is an 8-bit unsigned integer that represents the number of slot assignments contained in the message. The unit of measure is slots.
+
+###### *Slot Number*
+
+`Slot_Number` is a 16-bit unsigned integer that represents the Fixed rate based Slot Number assigned to the Network Interface Unit.
+
+##### **A.5.5.7.3 Channel Error Management**
+
+During periods of connection inactivity, the NIU shall enter an Idle Mode. Idle Mode is characterized by periodic transmission by the NIU of a <MAC> **Idle Message**. The Idle Mode transmission shall occur at a periodic rate sufficient for the INA to establish Packet Error Rate statistics.
+
+##### **<MAC> Idle Message (upstream contention or reserved)**
+
+The <MAC> **Idle Message** is sent by the NIU within the STB to the INA at predefined intervals (between 1 and 10 minutes) when upstream connection buffers are empty (see Table A.36).
+
+**Table A.36/J.112 – Idle message structure**
+
+|                                    | Bits | Bytes | Bit number/<br>Description |
+|------------------------------------|------|-------|----------------------------|
+| <code>Idle_Message() {</code>      |      |       |                            |
+| <code>Idle_Sequence_Count</code>   | 8    | 1     |                            |
+| <code>Power_Control_Setting</code> | 8    | 1     |                            |
+| <code>}</code>                     |      |       |                            |
+
+###### *Idle Sequence Count*
+
+`Idle_Sequence_Count` is an 8-bit unsigned integer representing the count of <MAC> IDLE MESSAGES transmitted while the NIU is Idle.
+
+###### *Power Control Setting*
+
+`Power_Control_Setting` is an 8-bit unsigned integer representing the absolute power attenuation that the NIU is using for upstream transmission.
+
+##### **A.5.5.7.4 Link management messages**
+
+##### **<MAC> Transmission Control Message (singlecast or broadcast downstream)**
+
+The <MAC> TRANSMISSION CONTROL MESSAGE is sent to the NIU from the INA to control several aspects of the upstream transmission. This includes stopping upstream transmission, re-enabling transmission from a NIU or group of NIU's and rapidly changing the upstream frequency being used by a NIU or group of NIU's. To identify a group of NIU's for switching frequencies, the <MAC> TRANSMISSION CONTROL MESSAGE is sent in broadcast mode with the `Old_Frequency` included in the message. When broadcast with the `Old_Frequency`, the NIU shall compare its current frequency value to `Old_Frequency`. When equal, the NIU shall switch to the new frequency specified in the message. When unequal, the NIU shall ignore the new frequency and remain on its current channel (see Table A.37).
+
+**Table A.37/J.112 – Transmission Control message structure**
+
+|                                                                                                     | Bits        | Bytes      | Bit number/<br>Description |
+|-----------------------------------------------------------------------------------------------------|-------------|------------|----------------------------|
+| Transmission_Control_Message() {                                                                    |             |            |                            |
+| <b>Transmission_Control_Field</b>                                                                   | <b>8</b>    |            |                            |
+| reserved                                                                                            | 3           |            | 7-5:                       |
+| Stop_Upstream_Transmission                                                                          | 1           |            | 4: {no, yes}               |
+| Start_Upstream_Transmission                                                                         | 1           |            | 3: {no, yes}               |
+| Old_Frequency_Included                                                                              | 1           |            | 2: {no, yes}               |
+| Switch_Downstream_OOB_Frequency                                                                     | 1           |            | 1: {no, yes}               |
+| Switch_Upstream_Frequency                                                                           | 1           |            | 0: {no, yes}               |
+| if (Transmission_Control_Field==<br>Switch_Upstream_Frequency &&<br>Old_Frequency_Included) {       |             |            |                            |
+| <b>Old_Upstream_Frequency</b>                                                                       | <b>(32)</b> | <b>(4)</b> |                            |
+| }                                                                                                   |             |            |                            |
+| if (Transmission_Control_Field==<br>Switch_Upstream_Frequency) {                                    |             |            |                            |
+| <b>New_Upstream_Frequency</b>                                                                       | <b>(32)</b> | <b>(4)</b> |                            |
+| <b>New_Upstream_Channel_Number</b>                                                                  | <b>3</b>    | <b>1</b>   | <b>7:5</b>                 |
+| <b>reserved</b>                                                                                     | <b>2</b>    |            | <b>4:3</b>                 |
+| <b>Upstream_Rate</b>                                                                                | <b>3</b>    |            | <b>2:0</b>                 |
+| <b>MAC_Flag_Set</b>                                                                                 | <b>5</b>    | <b>1</b>   | <b>7:3</b>                 |
+| <b>Reserved</b>                                                                                     | <b>3</b>    |            | <b>2:0</b>                 |
+| <b>New_Upstream_Frequency</b>                                                                       | <b>(32)</b> | <b>(4)</b> |                            |
+| }                                                                                                   |             |            |                            |
+| if (Transmission_Control_Field==<br>Switch_Downstream_OOB_Frequency &&<br>Old_Frequency_Included) { |             |            |                            |
+| <b>Old_Downstream_OOB_Frequency</b>                                                                 | <b>(32)</b> | <b>(4)</b> |                            |
+| }                                                                                                   |             |            |                            |
+| if (Transmission_Control_Field==<br>Switch_Downstream_OOB_Frequency) {                              |             |            |                            |
+| <b>New_Downstream_OOB_Frequency</b>                                                                 | <b>(32)</b> | <b>(4)</b> |                            |
+| <b>DownStream_Type</b>                                                                              | <b>8</b>    | <b>1</b>   |                            |
+| }                                                                                                   |             |            |                            |
+| }                                                                                                   |             |            |                            |
+
+###### *Transmission Control Field*
+
+`Transmission_Control_Field` specifies the control being asserted on the upstream channel.
+
+###### *Stop Upstream Transmission*
+
+`stop_upstream_transmission` is a boolean when set indicates that the NIU should halt its upstream transmission.
+
+###### *Start Upstream Transmission*
+
+`start_upstream_transmission` is a boolean when set indicates that the Network Interface Unit should resume transmission on its upstream channel. The NIU shall respond to the ranging and power calibration message regardless of the setting of the `start_upstream_transmission` bit.
+
+###### *Old Frequency Included*
+
+`Old_Frequency_Included` is a boolean when set indicates that the Old Frequency value is included in the message and should be used to determine if a switch in frequency is necessary.
+
+###### *Switch Downstream OOB Frequency*
+
+`switch_downstream_OOB_frequency` is a boolean when set indicates that a new downstream OOB frequency is included in the message.
+
+###### *Switch Upstream Frequency*
+
+`switch_upstream_frequency` is a boolean when set indicates that a new upstream frequency is included in the message. Typically, the `switch_upstream_frequency` and the `stop_upstream_transmission` are set simultaneously to allow the NIU to stop transmission and change channel. This would be followed by the <MAC> TRANSMISSION CONTROL MESSAGE with the `start_upstream_transmission` bit set.
+
+###### *Old Upstream Frequency*
+
+`Old_Upstream_Frequency` is a 32-bit unsigned integer representing the frequency that should be used by the NIU to compare with its current frequency to determine if a change in channel is required.
+
+###### *New Upstream Frequency*
+
+`New_Upstream_Frequency` is a 32-bit unsigned integer representing the reassigned upstream carrier center frequency. The unit of measure is Hz.
+
+`MAC_Flag_Set` is a 5-bit field representing the MAC Flag set assigned to the connection. In the OOB downstream timing, the eight sets of flags are assigned the numbers 1-8. In the IB downstream timing, the 16 sets of flags are assigned the numbers 1-16. In the case of a 3.088 Mbit upstream channel, this parameter represents the first of two successively assigned flag sets.
+
+`UpstreamStream_Rate` is a 3-bit enumerated type indicating the data rate for the upstream connection. {Upstream\_256K, Upstream\_1.544M, Upstream\_3.088M, 3..7 reserved}
+
+###### *Old Downstream OOB Frequency*
+
+`Old_Downstream_OOB_Frequency` is a 32-bit unsigned integer representing the frequency that should be used by the NIU to compare with its current frequency to determine if a change in channel is required.
+
+###### *New Downstream OOB Frequency*
+
+`New_Downstream_OOB_Frequency` is a 32-bit unsigned integer representing the reassigned downstream OOB carrier centre frequency. The unit of measure is Hz.
+
+`DownStream_Type` is an 8-bit enumerated type indicating the modulation format for the down stream connection. {reserved, QPSK\_1.544, QPSK\_3.088, 3..255 reserved}
+
+##### **Link Management Response Message (upstream contention, contention or reserved)**
+
+The <MAC> LINK MANAGEMENT RESPONSE MESSAGE is sent by the NIU to the INA to indicate reception and processing of the previously sent Link Management Message. The format of the message is shown in Table A.38.
+
+**Table A.38/J.112 – Link Management Acknowledge message format**
+
+|                                   | Bits | Bytes | Bit number/<br>Description |
+|-----------------------------------|------|-------|----------------------------|
+| Link_Management_Acknowledge() {   |      |       |                            |
+| <b>Link_Management_Msg_Number</b> | 16   | 2     |                            |
+| }                                 |      |       |                            |
+
+###### *Link Management Message Number*
+
+`Link_Management_Msg_Number` is a 16-bit unsigned integer representing the previously received link management message. The valid values for `Link_Management_Msg_Number` are shown in Table A.39.
+
+**Table A.39/J.112 – Link Management message number**
+
+| Message Name                 | Link_Management_Msg_Number              |
+|------------------------------|-----------------------------------------|
+| Transmission Control Message | Transmission Control Message Type Value |
+| Reprovision Message          | Reprovision Message Type Value          |
+
+##### **<MAC> Status Request Message (downstream singlecast)**
+
+The STATUS REQUEST message is sent by the INA to the NIU to retrieve information about the NIU's health, connection information and error states. The INA can request either the address parameters, error information, connection parameters or physical layer parameters from the NIU. The INA can only request one parameter type at a time to a particular NIU (see Table A.40).
+
+**Table A.40/J.112 – Status Request message structure**
+
+|                             | Bits | Bytes | Bit number/<br>Description |
+|-----------------------------|------|-------|----------------------------|
+| Status_Request() {          |      |       |                            |
+| <b>Status_Control_Field</b> | 8    | 1     |                            |
+| <i>reserved</i>             | 5    |       | 3-7:                       |
+| Status_Type                 | 3    |       | 0-2:{enum type}            |
+| }                           |      |       |                            |
+
+###### *Status Control Field*
+
+`Status_Control_Field` is a 3-bit enumerated type that indicates the status information the NIU should return.
+
+```
+enum Status_Control_Field {Address_Params, Error_Params,
+Connection_Params,Physical_Layer_Params, reserved 4..7};
+```
+
+##### **<MAC> Status Response Message (Upstream Contention, contention or reserved)**
+
+The <MAC> STATUS RESPONSE MESSAGE is sent by the NIU in response to the <MAC> STATUS REQUEST MESSAGE issued by the INA. The contents of the information provided in this message will vary depending on the request made by the INA and the state of the NIU. The message must be dissociated into separate messages if the resulting length of the message exceeds 40 bytes (see Table A.41).
+
+**Table A.41/J.112 – Status Response message structure**
+
+|                                                                      | Bits  | Bytes | Bit number/<br>Description |
+|----------------------------------------------------------------------|-------|-------|----------------------------|
+| Status_Response() {                                                  |       |       |                            |
+| <b>NIU_Status</b>                                                    | 32    | 4     |                            |
+| <b>Response_Fields_Included</b>                                      | 8     | 1     |                            |
+| reserved                                                             | 4     |       | 4-7:                       |
+| Address_Params_Included                                              | 1     |       | 3:{no, yes}                |
+| Error_Information_Included                                           | 1     |       | 2:{no, yes}                |
+| Connection_Params_Included                                           | 1     |       | 1:{no, yes}                |
+| Physical_Layer_Params_Included                                       | 1     |       | 0:{no, yes}                |
+| if (Response_Fields_Included ==<br>Address_Params_Included) {        |       |       |                            |
+| <b>NSAP_Address</b>                                                  | (160) | (20)  |                            |
+| <b>MAC_Address</b>                                                   | (48)  | (6)   |                            |
+| }                                                                    |       |       |                            |
+| if (Response_Fields_Included ==<br>Error_Information_Included) {     |       |       |                            |
+| <b>Number_Error_Codes_Included</b>                                   | (8)   | (1)   |                            |
+| for(i=0;i<Number_Error_Codes_Included;<br>i++) {                     |       |       |                            |
+| <b>Error_Param_code</b>                                              | (8)   | (1)   |                            |
+| <b>Error_Param_Value</b>                                             | (16)  | (2)   |                            |
+| }                                                                    |       |       |                            |
+| }                                                                    |       |       |                            |
+| if (Response_Fields_Included ==<br>Connection_Params_Included) {     |       |       |                            |
+| <b>Number_of_Connections</b>                                         | (8)   | (1)   |                            |
+| for(i=0;i<Number_of_Connections;i++) {                               |       |       |                            |
+| <b>Connection_ID</b>                                                 | (32)  | (4)   |                            |
+| }}                                                                   |       |       |                            |
+| if (Response_Fields_Included ==<br>Physical_Layer_Params_Included) { |       |       |                            |
+| <b>Power_Control_Setting</b>                                         | (8)   | (1)   |                            |
+| <b>Time_Offset_Value</b>                                             | (32)  | (4)   |                            |
+| <b>Upstream_Frequency</b>                                            | (32)  | (4)   |                            |
+| <b>Downstream_Frequency</b>                                          | (32)  | (4)   |                            |
+| }                                                                    |       |       |                            |
+| }                                                                    |       |       |                            |
+
+###### *NIU Status*
+
+`NIU_Status` is a 32-bit unsigned integer that indicates the current state of the NIU.
+
+|                                                                                                                                               |
+|-----------------------------------------------------------------------------------------------------------------------------------------------|
+| <code>NIU_Status { Calibration_Operation_Complete,<br/>Default_Connection_Established,<br/>Network_Address Registered,<br/>,reserved};</code> |
+|-----------------------------------------------------------------------------------------------------------------------------------------------|
+
+###### *Response Fields Included*
+
+`Response_Fields_Included` is an 8-bit unsigned integer that indicates what parameters are contained in the upstream status response.
+
+###### *NSAP Address*
+
+`NSAP_Address` is a 20-byte address assigned to the NIU.
+
+###### *MAC Address*
+
+`MAC_Address` is a 6-byte address assigned to the NIU.
+
+###### *Number of Error Codes Included*
+
+`Number_Error_Codes_Included` is an 8-bit unsigned integer that indicates the number of error codes are contained in the response.
+
+###### *Error Parameter Code*
+
+`Error_Parameter_Code` is an 8-bit unsigned integers representing the type of error reported by the NIU (see Table A.42).
+
+**Table A.42/J.112 – Error parameter code**
+
+| <b>Error Parameter Code Name</b>                | <b>Error Parameter Code</b> |
+|-------------------------------------------------|-----------------------------|
+| <code>Framing_Bit_Error_Count</code>            | <code>0x00</code>           |
+| <code>Slot_Configuration_CRC_Error_Count</code> | <code>0x01</code>           |
+| <code>Reed_Solomon_Error_Count</code>           | <code>0x02</code>           |
+| <code>ATM_Packet_Loss_Count</code>              | <code>0x03</code>           |
+
+###### *Error Parameter Value*
+
+`Error_Parameter_Value` is a 16-bit unsigned integers representing error counts detected by the NIU.
+
+###### *Number of Connections*
+
+`Number_of_Connections` is an 8-bit unsigned integer that indicates the number of connections that are specified in the response. Specifically, if the number of connections is too large to have a MAC message with less than 40 bytes, it is possible to send separate messages with only the number of connections indicated in each message.
+
+###### *ConnectionID*
+
+`Connection_ID` is a 32-bit unsigned integer representing the global connection Identifier used by the NIU for this connection.
+
+###### *Power Control Setting*
+
+`Power_Control_Setting` is an 8-bit unsigned integer representing the absolute power attenuation that the NIU is using for upstream transmission.
+
+###### *Time Offset Value*
+
+`Time_Offset_Value` is a 16-bit short integer representing a relative offset of the upstream transmission timing. A negative value indicates an adjustment forward in time. A positive value indicates an adjustment back in time. The unit of measure is 100 ns.
+
+###### *Upstream Frequency*
+
+`Upstream_Frequency` is a 32-bit unsigned integer representing the channel assigned to the connection. The unit of measure is in Hz.
+
+###### *Downstream Frequency*
+
+`Downstream_Frequency` is a 32-bit unsigned integer representing the Frequency where the connection resides. The unit of measure is in Hz.
+
+# **Annex B**
+
+# **Data-over-cable radio frequency interface**
+
+## **B.1 Scope and purpose**
+
+### **B.1.1 Scope**
+
+This annex is derived from radio-frequency interface specifications for high-speed data-over-cable systems that have been developed in North America.
+
+### **B.1.2 Requirements**
+
+Throughout this Recommendation, the words that are used to define the significance of particular requirements are capitalized. These words are:
+
+- **"MUST"** This word or the adjective **"REQUIRED"** means that the item is an absolute requirement of this specification.
+- **"MUST NOT"** This phrase means that the item is an absolute prohibition of this specification.
+- **"SHOULD"** This word or the adjective **"RECOMMENDED"** means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighed before choosing a different course.
+- **"SHOULD NOT"** This phrase means that there may exist valid reasons in particular circumstances when the listed behaviour is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behaviour described with this label.
+- **"MAY"** This word or the adjective **"OPTIONAL"** means that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product, for example, another vendor may omit the same item.
+
+Other text is descriptive or explanatory.
+
+### B.1.3 Background
+
+#### B.1.3.1 Service goals
+
+Cable operators are interested in deploying high-speed data communications systems on cable television systems. Thus, it has been decided to prepare a series of interface specifications that will permit the early definition, design, development and deployment of data-over-cable systems on an uniform, consistent, open, non-proprietary, multi-vendor interoperable basis.
+
+The intended service will allow transparent bi-directional transfer of Internet Protocol (IP) traffic, between the cable system headend and customer locations, over an all-coaxial or Hybrid-Fiber/Coax (HFC) cable network. This is shown in simplified form in Figure B.1-1.
+
+The transmission path over the cable system is realized at the headend by a Cable Modem Termination System (CMTS), and at each customer location by a Cable Modem (CM). At the headend (or hub), the interface to the data-over-cable system is called the Cable Modem Termination System – Network-Side Interface (CMTS-NSI) and is specified in [MCNS3]. At the customer locations, the interface is called the cable-modem-to-customer-premises-equipment interface (CMCI) and is specified in [MCNS4]. The intent is for the MCNS operators to transparently transfer IP traffic between these interfaces, including but not limited to datagrams, DHCP, ICMP, and IP Group addressing (broadcast and multicast).
+
+![Diagram of transparent IP traffic through the data-over-cable system](d9638e837004a4e09dbbc50b8aecbd5f_img.jpg)
+
+The diagram illustrates the flow of IP traffic through a data-over-cable system. On the left, a box labeled 'Wide-Area Network' is connected via a double-headed arrow to a box labeled 'Cable Modem Termination System CMTS'. This connection is labeled 'CMTS Network Side Interface'. From the CMTS, a single-headed arrow points right through a box labeled 'Cable Network' to a box labeled 'Cable Modem (CM)'. From the CM, a double-headed arrow points right to a box labeled 'Customer Premises Equipment' (represented by a computer monitor and tower). This connection is labeled 'CM Customer Premises Equipment Interface'. A bracket underneath the CMTS, Cable Network, and CM is labeled 'Transparent IP traffic through the system'.
+
+Diagram of transparent IP traffic through the data-over-cable system
+
+T0904770-97/d044
+
+**Figure B.1-1/J.112 – Transparent IP traffic through the data-over-cable system**
+
+#### B.1.3.2 Reference architecture
+
+The reference architecture for the data-over-cable services and interfaces is shown in Figure B.1-2.
+
+##### B.1.3.2.1 Categories of interface specification
+
+The basic reference architecture of Figure B.1-2 involves three categories of interface. These have been developed in phases:
+
+###### a) Phase 1
+
+**Data Interfaces** – These are the CMCI [MCNS4] and CMTS-NSI [MCNS3], corresponding respectively to the cable-modem-to-Customer-Premises-Equipment (CPE) interface (for example, between the customer's computer and the cable modem), and the cable modem termination system network-side interface between the cable modem termination system and the data network.
+
+###### b) Phase 2
+
+**Operations Support Systems Interfaces** – These are network element management layer interfaces between the network elements and the high-level Operations Support Systems (OSSs) which support the basic business processes, and are documented in [MCNS5].
+
+**Telephone Return Interface** – CMTRI – This is the interface between the cable modem and a telephone return path, for use in cases where the return path is not provided or not available via the cable network, and is documented in [MCNS6].
+
+Recommendation J.112 (03/98)
+
+86
+
+![Figure B.1-2/J.112 – Data-over-cable reference architecture. A complex block diagram showing the components and data flow of a cable data system. It connects external networks like PSTN and WAN to a Distribution Hub/Headend, which then connects via fiber and coax to customer premise equipment including cable modems and PCs.](abeba89144744fac6a1571aa9f94889e_img.jpg)
+
+Distribution Hub or Headend
+
+Operations Support System
+
+Data Over Cable System  
+OSS Interface, DOCS-OSSI
+
+Cable Modem Termination System  
+Downstream RF Interface
+
+Cable Modem Termination System  
+Network Side Interface,  
+CMTS-NSI
+
+Cable Modem Termination System
+
+Upstream splitter and filter bank
+
+Cable Modem Termination System Upstream RF Interface
+
+Security and Access Controller
+
+Telco Return Access Concentrator (TRAC)
+
+Copper Pairs, DS1 or DS3
+
+PSTN
+
+Generic Headend Switch or Backbone Transport Adapter
+
+WAN (Backbone Network)
+
+Local Server Facility
+
+Data Over Cable Security System (DOCSS)
+
+WAN (Remote Server Facility)
+
+Mod
+
+Demod
+
+Data
+
+Data
+
+Network Termination
+
+Video 1
+
+Video 2
+
+Combiner
+
+Tx
+
+Rx
+
+Fiber
+
+50-860 MHz
+
+5-42 MHz
+
+O/E Node
+
+Distribution Network
+
+O/E Node
+
+O/E Node
+
+Coax
+
+Cable Modem
+
+Security Module
+
+Removable Customer Premise Equipment
+
+Cable Modem to RF Interface
+
+Cable Modem to CPE Interface, CMCI
+
+Telco return
+
+Cable Modem Telco Return Interface, CMTRI
+
+Figure B.1-2/J.112 – Data-over-cable reference architecture. A complex block diagram showing the components and data flow of a cable data system. It connects external networks like PSTN and WAN to a Distribution Hub/Headend, which then connects via fiber and coax to customer premise equipment including cable modems and PCs.
+
+**Figure B.1-2/J.112 – Data-over-cable reference architecture**
+
+T0904780-97/d045
+
+###### **c) Phase 3**
+
+**RF Interfaces** – The RF interfaces defined in this Recommendation are the following:
+
+- between the cable modem and the cable network;
+- between the CMTS and the cable network, in the downstream direction (traffic toward the customer);
+- between the CMTS and the cable network, in the upstream direction (traffic from the customer).
+
+###### **Security requirements**
+
+- the Data Over Cable Security System (DOCSS) is defined in [MCNS2];
+- the CM Removable Security Module (RSM) is defined in [MCNS7];
+- Baseline data-over-cable security is defined in [MCNS8].
+
+##### **B.1.3.2.2 Data-Over-Cable Interface Documents**
+
+A list of the documents in the Data-Over-Cable Interface Specifications family is provided below. For updates, please refer to URL <http://www.cablemodem.com>.
+
+| Designation | Title                                                                                                                                        |
+|-------------|----------------------------------------------------------------------------------------------------------------------------------------------|
+| SP-CMCI     | Cable Modem to Customer Premises Equipment Interface Specification                                                                           |
+| SP-CMTS-NSI | Cable Modem Termination System Network Side Interface Specification                                                                          |
+| SP-CMTRI    | Cable Modem Telco Return Interface Specification                                                                                             |
+| SP-OSSI     | Operations Support System Interface Specification                                                                                            |
+| SP-RFI      | Radio Frequency Interface Specification                                                                                                      |
+| SP-DOCSS    | Data Over Cable Security System (DOCSS) Specification                                                                                        |
+| SP-RSM      | Removable Security Module Specification                                                                                                      |
+| SP-BDS      | Baseline Data-Over-Cable Security Specification                                                                                              |
+| SP          | Specification                                                                                                                                |
+| TR          | Technical Report (provides a context for understanding and applying the specification – documents of this type may be issued in the future.) |
+
+#### **B.1.3.3 Server location**
+
+This annex refers to several servers which are central to the system operation (e.g. provision and security servers).
+
+The message sequence charts used as examples within this annex show sample message exchanges in which access to the servers is via the CMTS. It is important to note that access to these servers need not necessarily be via the CMTS, but MAY be via any CM suitably configured. In this case, the scenarios become slightly more complex, as the message flows are as shown in Figure B.1-3. Allowing placement of these components to be at locations other than the CMTS allows the system operator the maximum flexibility in server placement and network configuration. Note that the CMTS MUST be able to initialize without access to the servers in Figure B.1-3.
+
+## **B.2 Functional assumptions**
+
+This subclause describes the characteristics of cable television plant to be assumed for the purposes of operation of the data-over-cable system. It is not a description of CMTS or CM parameters. The data-over-cable system MUST operate satisfactorily in the environment described in this subclause.
+
+![Figure B.1-3/J.112 – Server location not at CMTS. The diagram shows a CMTS connected to a bus. CM1 is connected to the bus. CM2 is connected to the bus and to a Servers box. Below this, a section titled 'Message flows:' shows a sequence of boxes: CM1, CMTS, CM2, and Server. Arrows indicate bidirectional message flow between CM1 and CMTS, CMTS and CM2, and CM2 and Server.](ca86f53f9735fe98b6c6003d1b759f64_img.jpg)
+
+Message flows:
+
+CM1 ↔ CMTS ↔ CM2 ↔ Server
+
+T0904790-97/d046
+
+Figure B.1-3/J.112 – Server location not at CMTS. The diagram shows a CMTS connected to a bus. CM1 is connected to the bus. CM2 is connected to the bus and to a Servers box. Below this, a section titled 'Message flows:' shows a sequence of boxes: CM1, CMTS, CM2, and Server. Arrows indicate bidirectional message flow between CM1 and CMTS, CMTS and CM2, and CM2 and Server.
+
+**Figure B.1-3/J.112 – Server location not at CMTS**
+
+### B.2.1 Broadband access network
+
+A coaxial-based broadband access network is assumed. This may take the form of either an all-coax or Hybrid-Fiber/Coax (HFC) network. The generic term "cable network" is used here to cover all cases.
+
+A cable network uses a shared-medium, tree-and-branch architecture with analogue transmission. The key functional characteristics assumed in this annex are the following:
+
+- Two-way transmission.
+- A maximum optical/electrical spacing between the CMTS and the most distant customer terminal of 100 miles, although typical maximum separation may be 10-15 miles.
+- A maximum differential optical/electrical spacing between the CMTS and the closest and most distant modems of 100 miles, although this would typically be limited to 15 miles.
+
+### B.2.2 Equipment assumptions
+
+#### B.2.2.1 Frequency plan
+
+In the downstream direction, the cable system is assumed to have a passband with a lower edge at 50 or 54 MHz and an upper edge which is implementation-dependent but is typically in the range of 300 to 860 MHz. Within that passband, NTSC analogue television signals in 6 MHz channels are assumed to be present on the standard, HRC or IRC frequency plans of EIA Interim Standard IS-6, as well as other narrowband and wideband digital signals.
+
+In the upstream direction, the cable system may have a subsplit (5-30 MHz) or extended subsplit (5-42 MHz) passband. NTSC analogue television signals in 6-MHz channels may be present, as well as other signals.
+
+#### B.2.2.2 Compatibility with other services
+
+The CM and CMTS MUST coexist with the other services on the cable network. In particular:
+
+- a) they MUST operate satisfactorily in cable spectrum assigned for CMTS-CM interoperation while the balance of the cable spectrum is occupied by any combination of television and other signals; and
+- b) they MUST NOT cause harmful interference to any other services that are assigned to the cable network in spectrum outside of that allocated to the CMTS.
+
+#### B.2.2.3 Fault isolation impact on other users
+
+As the data-over-cable system is a shared-media, point-to-multipoint system, fault-isolation procedures MUST take into account the potential harmful impact of faults and fault-isolation procedures on numerous users of the data-over-cable and other services.
+
+### B.2.3 RF channel assumptions
+
+The data-over-cable system, configured with at least one set of defined physical-layer parameters (e.g. modulation, forward error correction, symbol rate, etc.) from the range of configuration settings described in this specification, must be capable of operating with a 1500-byte packet loss rate of less than one percent while forwarding at least 100 packets per second on cable networks having characteristics defined in B.2.3.
+
+#### B.2.3.1 Transmission downstream
+
+The RF channel transmission characteristics of the cable network in the downstream direction assumed for the purposes of minimal operating capability are described in Table B.2-1. This assumes nominal analogue video carrier level (peak envelope power) in a 6 MHz channel bandwidth. All conditions are present concurrently.
+
+**Table B.2-1/J.112 – Assumed downstream RF channel transmission characteristics**
+
+| Parameter                                                                                                                                                                                             | Value                                                                                                                                                           |
+|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Frequency range                                                                                                                                                                                       | Cable system normal downstream operating range is from 50 MHz to as high as 860 MHz. However, the values in this table apply only at frequencies $\geq 88$ MHz. |
+| RF channel spacing (design bandwidth)                                                                                                                                                                 | 6 MHz                                                                                                                                                           |
+| Transit delay from headend to most distant customer                                                                                                                                                   | $\leq 0.800$ ms (typically much less)                                                                                                                           |
+| Carrier-to-noise ratio in a 6 MHz band (analogue video level)                                                                                                                                         | Not less than 35 dB (Note 4)                                                                                                                                    |
+| Carrier-to-interference ratio for total power (discrete and broadband ingress signals)                                                                                                                | Not less than 35 dB within the design bandwidth                                                                                                                 |
+| Composite triple beat distortion for analogue modulated carriers                                                                                                                                      | Not greater than $-50$ dBc within the design bandwidth                                                                                                          |
+| Composite second order distortion for analogue modulated carriers                                                                                                                                     | Not greater than $-50$ dBc within the design bandwidth                                                                                                          |
+| Cross-modulation level                                                                                                                                                                                | Not greater than $-40$ dBc within the design bandwidth                                                                                                          |
+| Amplitude ripple                                                                                                                                                                                      | 0.5 dB within the design bandwidth                                                                                                                              |
+| Group delay ripple in the spectrum occupied by the CMTS                                                                                                                                               | 75 ns within the design bandwidth                                                                                                                               |
+| Micro-reflections bound for dominant echo                                                                                                                                                             | $-10$ dBc @ $\leq 0.5$ $\mu$ s, $-15$ dBc @ $\leq 1.0$ $\mu$ s<br>$-20$ dBc @ $\leq 1.5$ $\mu$ s, $-30$ dBc @ $> 1.5$ $\mu$ s                                   |
+| Carrier hum modulation                                                                                                                                                                                | Not greater than $-26$ dBc (5%)                                                                                                                                 |
+| Burst noise                                                                                                                                                                                           | Not longer than 25 $\mu$ s at a 10 Hz average rate                                                                                                              |
+| Seasonal and diurnal signal level variation                                                                                                                                                           | 8 dB                                                                                                                                                            |
+| Signal level slope, 50-750 MHz                                                                                                                                                                        | 16 dB                                                                                                                                                           |
+| Maximum analogue video carrier level at the CM input, inclusive of above signal level variation                                                                                                       | 17 dBmV                                                                                                                                                         |
+| Lowest analogue video carrier level at the CM input, inclusive of above signal level variation                                                                                                        | $-5$ dBmV                                                                                                                                                       |
+| NOTE 1 – Transmission is from the headend combiner to the CM input at the customer location.                                                                                                          |                                                                                                                                                                 |
+| NOTE 2 – For measurements above, the normal downstream operating frequency band (except hum), impairments are referenced to the highest-frequency NTSC carrier level.                                 |                                                                                                                                                                 |
+| NOTE 3 – For hum measurements above, the normal downstream operating frequency band, a continuous-wave carrier is sent at the test frequency at the same level as the highest-frequency NTSC carrier. |                                                                                                                                                                 |
+| NOTE 4 – This presumes that the digital carrier is operated at analogue peak carrier level. When the digital carrier is operated below the analogue peak carrier level, this C/N may be less.         |                                                                                                                                                                 |
+| NOTE 5 – Measurement methods defined in [NCTA] or [CableLabs2].                                                                                                                                       |                                                                                                                                                                 |
+
+#### B.2.3.2 Transmission upstream
+
+The RF channel transmission characteristics of the cable network in the upstream direction assumed for the purposes of minimal operating capability are described in Table B.2-2. All conditions are present concurrently.
+
+**Table B.2-2/J.112 – Assumed upstream RF channel transmission characteristics**
+
+| Parameter                                                                                                                                                                                | Value                                                                                                          |
+|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------|
+| Frequency range                                                                                                                                                                          | 5 to 42 MHz edge to edge                                                                                       |
+| Transit delay from the most distant CM to the nearest CM or CMTS                                                                                                                         | $\leq 0.800$ ms (typically much less)                                                                          |
+| Carrier-to-noise ratio                                                                                                                                                                   | Not less than 25 dB                                                                                            |
+| Carrier-to-ingress power (the sum of discrete and broadband ingress signals) ratio                                                                                                       | Not less than 25 dB (Note 2)                                                                                   |
+| Carrier-to-interference (the sum of noise, distortion, common-path distortion and cross-modulation) ratio                                                                                | Not less than 25 dB                                                                                            |
+| Carrier hum modulation                                                                                                                                                                   | Not greater than $-23$ dBc (7.0 %)                                                                             |
+| Burst noise                                                                                                                                                                              | Not longer than $10\ \mu\text{s}$ at a 1 kHz average rate for most cases (Notes 3, 4 and 5)                    |
+| Amplitude ripple                                                                                                                                                                         | 5-42 MHz: 0.5 dB/MHz                                                                                           |
+| Group delay ripple                                                                                                                                                                       | 5-42 MHz: 200 ns/MHz                                                                                           |
+| Micro-reflections – Single echo                                                                                                                                                          | $-10$ dBc @ $\leq 0.5\ \mu\text{s}$<br>$-20$ dBc @ $\leq 1.0\ \mu\text{s}$<br>$-30$ dBc @ $> 1.0\ \mu\text{s}$ |
+| Seasonal and diurnal signal level variation                                                                                                                                              | Not greater than 8 dB min to max                                                                               |
+| NOTE 1 – Transmission is from the CM output at the customer location to the headend.                                                                                                     |                                                                                                                |
+| NOTE 2 – Ingress avoidance or tolerance techniques MAY be used to ensure operation in the presence of time-varying discrete ingress signals that could be as high as 0 dBc [CableLabs1]. |                                                                                                                |
+| NOTE 3 – Amplitude and frequency characteristics sufficiently strong to partially or wholly mask the data carrier.                                                                       |                                                                                                                |
+| NOTE 4 – CableLabs report containing distribution of return-path burst noise measurements and measurement method is forthcoming.                                                         |                                                                                                                |
+| NOTE 5 – Impulse noise levels more prevalent at lower frequencies ( $<15$ MHz).                                                                                                          |                                                                                                                |
+
+##### B.2.3.2.1 Availability
+
+Typical cable network availability is considerably greater than 99 %.
+
+### B.2.4 Transmission levels
+
+The nominal power level of the downstream CMTS 64 QAM signal(s) within a 6 MHz channel is targeted to be in the range  $-10$  dBc to  $-6$  dBc relative to analogue video carrier level and will normally not exceed analogue video carrier level. The nominal power level of the upstream CM signal(s) will be as low as possible to achieve the required margin above noise and interference. Uniform power loading per unit bandwidth is commonly followed in setting upstream signal levels, with specific levels established by the cable network operator to achieve the required carrier-to-noise and carrier-to-interference ratios.
+
+### B.2.5 Frequency inversion
+
+There will be no frequency inversion in the transmission path in either the downstream or upstream directions, i.e. a positive change in frequency at the input to the cable network will result in a positive change in frequency at the output.
+
+## B.3 Communication protocols
+
+This subclause provides a high-level overview of the communication protocols that MUST be used in the data-over-cable system. Detailed specifications for the physical media dependent, downstream transmission, and media access control sublayers are provided in B.4, B.5, and B.6, respectively.
+
+### B.3.1 Protocol stack
+
+The CM and CMTS operate as forwarding agents and also as end-systems (hosts). The protocol stacks used in these modes differ as shown below.
+
+The principal function of the cable modem system is to transmit Internet Protocol (IP) packets transparently between the headend and the subscriber location. Certain management functions also ride on IP, so that the protocol stack on the cable network is as shown in Figure B.3-1 (this does not restrict the generality of IP transparency between the headend and the customer). These management functions include, for example, supporting spectrum management functions and the downloading of software.
+
+#### B.3.1.1 CM and CMTS as hosts
+
+CMs and CMTSs will operate as IP and LLC hosts in terms of IEEE Standard 802 [IEEE 802] for communication over the cable network. The protocol stack at the CM and CMTS RF interfaces is shown in Figure B.3-1.
+
+The CM and CMTS MUST function as IP hosts. As such, the CM and CMTS MUST support IP and ARP over DIX link-layer framing (see [DIX]). The CM and CMTS MAY also support IP and ARP over SNAP framing [RFC-1042].
+
+The CM and CMTS also MUST function as LLC hosts. As such, the CM and CMTS MUST respond appropriately to TEST and XID requests per [ISO/IEC 8802-2].
+
+![Protocol stack diagram on the RF interface showing layers from SNMP down to PMD.](c78f017dab5586c098c5d7c6a8f1d432_img.jpg)
+
+The diagram illustrates the protocol stack on the RF interface. At the top, four boxes representing management protocols (SNMP, TFTP, DHCP, and Security Management) are connected to a single UDP layer. Below UDP is the IP, ICMP layer. To the right of the IP, ICMP layer is an ARP layer, which is connected to the IP, ICMP layer and the LLC/DIX layer. Below the IP, ICMP layer is the LLC/DIX layer. Below the LLC/DIX layer is the Link Security layer. Below the Link Security layer is the MAC layer. Below the MAC layer is the Transmission Convergence (downstream only) layer. At the bottom is the PMD layer. The layers are stacked vertically, with lines connecting them to show the flow of data.
+
+T0905990-97/d047
+
+Protocol stack diagram on the RF interface showing layers from SNMP down to PMD.
+
+Figure B.3-1/J.112 – Protocol stack on the RF interface
+
+#### B.3.1.2 Data forwarding through the CM and CMTS
+
+##### B.3.1.2.1 General
+
+Data forwarding through the CMTS MAY be transparent bridging, or MAY employ network-layer forwarding (routing, IP switching) as shown in Figure B.3-2.
+
+![Figure B.3-2/J.112 – Data forwarding through the CM and CMTS. This diagram shows two protocol stacks: CMTS stack and CM stack. The CMTS stack has an IP layer at the top, followed by a Data Link Layer containing Forwarding, 802.2/DIX LLC, Link security, Cable MAC, Downstream Trans Conv, and Cable PMD. The CM stack has an IP layer at the top, followed by 802.2/DIX LLC, Transparent bridging, 802.2/DIX LLC, Link security, Cable MAC, Downstream Trans Conv, Cable PMD, 802.3/DIX MAC, and 802.3 10Base-T. Arrows indicate interfaces: CMTS-NSI Interface to/from Network Equipment on the left, Cable Network Transmission in the center, and CMCI Interface to/from Customer Premises Equipment on the right. Reference T0906000-97/d048 is shown.](de63e4b6d8b0aa76b85e1fe3236eac27_img.jpg)
+
+Figure B.3-2/J.112 – Data forwarding through the CM and CMTS. This diagram shows two protocol stacks: CMTS stack and CM stack. The CMTS stack has an IP layer at the top, followed by a Data Link Layer containing Forwarding, 802.2/DIX LLC, Link security, Cable MAC, Downstream Trans Conv, and Cable PMD. The CM stack has an IP layer at the top, followed by 802.2/DIX LLC, Transparent bridging, 802.2/DIX LLC, Link security, Cable MAC, Downstream Trans Conv, Cable PMD, 802.3/DIX MAC, and 802.3 10Base-T. Arrows indicate interfaces: CMTS-NSI Interface to/from Network Equipment on the left, Cable Network Transmission in the center, and CMCI Interface to/from Customer Premises Equipment on the right. Reference T0906000-97/d048 is shown.
+
+Figure B.3-2/J.112 – Data forwarding through the CM and CMTS
+
+Data forwarding through the CM is link-layer transparent bridging, as shown in Figure B.3-2. Forwarding rules are similar to [ISO/IEC 10038] with the modifications described in B.3.1.2.2 and B.3.1.2.3. This allows the support of multiple network layers.
+
+Forwarding of IP traffic MUST be supported. Support of other network layer protocols is OPTIONAL. The ability to restrict the network layer to a single protocol such as IP is REQUIRED.
+
+Support for the 802.1d spanning tree protocol of [ISO/IEC 10038] with the modifications described in B.3.1.2.3 is OPTIONAL for CMs intended for residential use. CMs intended for commercial use and bridging CMTSs MUST support this version of spanning tree (see Appendix B.VIII). CMs and CMTSs MUST include the ability to filter (and disregard) 802.1d BPDUs.
+
+This specification assumes that CMs intended for residential use will not be connected in a configuration which would create network loops such as that shown in Figure B.3-3.
+
+![Figure B.3-3/J.112 – Example condition for network loops. This diagram shows a network topology. A CMTS is connected to a Cable network. The Cable network branches to two CMs, CM #1 and CM #2. Both CM #1 and CM #2 are connected to a Local ISO 8802 network. The Local ISO 8802 network is connected to a CPE. Reference T0906010-97/d049 is shown.](985267cff5b5d65ce5c180ff2ef37118_img.jpg)
+
+Figure B.3-3/J.112 – Example condition for network loops. This diagram shows a network topology. A CMTS is connected to a Cable network. The Cable network branches to two CMs, CM #1 and CM #2. Both CM #1 and CM #2 are connected to a Local ISO 8802 network. The Local ISO 8802 network is connected to a CPE. Reference T0906010-97/d049 is shown.
+
+Figure B.3-3/J.112 – Example condition for network loops
+
+##### **B.3.1.2.2 CMTS forwarding rules**
+
+At the CMTS, if link-layer forwarding is used, then it **MUST** conform to the following general 802.1d guidelines:
+
+- Link-layer frames between a given pair of end-stations **MUST** be delivered in order.
+- Link-layer frames **MUST NOT** be duplicated.
+- Stale frames (those that cannot be delivered in a timely fashion) **MUST** be discarded.
+
+The address-learning and -aging mechanisms used are vendor-dependent.
+
+If network-layer forwarding is used, then the CMTS should conform to IETF Router Requirements [RFC-1812] with respect to its CMTS-RFI and CMTS-NSI interfaces.
+
+Conceptually, the CMTS forwards data packets at two abstract interfaces: between the CMTS-RFI and the CMTS-NSI, and between the upstream and downstream channels. The CMTS **MAY** use any combination of link-layer (bridging) and network-layer (routing) semantics at each of these interfaces. The methods used at the two interfaces need not be the same.
+
+Forwarding between the upstream and downstream channels within a MAC layer differs from traditional LAN forwarding in that:
+
+- A single channel is simplex, and cannot be considered a complete interface for most protocol (e.g. 802.1d spanning tree, Routing Information Protocol per [RFC-1058]) purposes.
+- Upstream channels are essentially point-to-point, whereas downstream channels are shared-media.
+- As a public network, policy decisions may override full connectivity.
+
+For these reasons, an abstract entity called the MAC Forwarder exists within the CMTS to provide connectivity between stations within a MAC domain (see B.3.2).
+
+### **B.3.1.2.3 CM forwarding rules**
+
+Data forwarding through the CM is link-layer bridging with the following specific rules.
+
+#### **B.3.1.2.3.1 Address learning**
+
+- The CM **MUST** acquire Ethernet MAC addresses of connected CPE devices, either from the provisioning process or from learning, until the CM acquires its maximum number of CPE addresses (a device-dependent value). Once the CM acquires its maximum number of CPE addresses, then newly discovered CPE addresses **MUST NOT** replace previously acquired addresses. The CM must support acquisition of at least one CPE address.
+- The CM **MUST** allow configuration of CPE addresses during the provisioning process (up to its maximum number of CPE addresses) to support configurations in which learning is not practical nor desired.
+- Addresses provided during the CM provisioning **MUST** take preference over learned addresses.
+- CPE addresses **MUST NOT** be aged out.
+- On a CM reset (e.g. a power cycle), all learned addresses **MUST** be discarded (they are not retained in non-volatile storage, to allow modification of user MAC addresses or movement of the CM).
+
+#### **B.3.1.2.3.2 Forwarding**
+
+CM forwarding in both directions **MUST** conform to the following general 802.1d guidelines:
+
+- Link-layer frames between a given pair of end-stations **MUST** be delivered in order.
+- Link-layer frames **MUST NOT** be duplicated.
+- Stale frames (those that cannot be delivered in a timely fashion) **MUST** be discarded.
+
+Cable-Network-to-Ethernet forwarding MUST follow the following specific rules:
+
+- Frames addressed to unknown destinations MUST NOT be forwarded from the cable port to the Ethernet port.
+- Broadcast frames MUST be forwarded to the Ethernet port, unless they are from source addresses which are provisioned or learned as supported CPE devices, in which case they MUST NOT be forwarded.
+- Multicast frames MUST be forwarded to the Ethernet ports in accordance with filtering configuration settings specified by the cable operator's operations and business support systems, unless they are from source addresses which are provisioned or learned as supported CPE devices, in which case they MUST NOT be forwarded.
+
+Ethernet-to-Cable-Network forwarding MUST follow the following specific rules:
+
+- Frames addressed to unknown destinations MUST be forwarded from the Ethernet port to the cable port.
+- Broadcast frames MUST be forwarded to the cable port.
+- Multicast frames MUST be forwarded to the cable port in accordance with filtering configuration settings specified by the cable operator's operations and business support systems.
+- Frames from source addresses other than those provisioned or learned as supported CPE devices MUST NOT be forwarded.
+- If a single-user CM has learned a supported address, it MUST NOT forward data from a second source. Other (non-supported) CPE source addresses MUST be learned from the Ethernet port and this information used to filter local traffic as in a traditional learning bridge.
+- If a single-user CM has learned A as its supported CPE device and learned B as a second device connected to the Ethernet port, it MUST filter any traffic from A to B.
+
+### B.3.2 The MAC Forwarder
+
+The MAC Forwarder is a MAC sublayer that resides on the CM/MTS just below the MAC Service Access Point (MSAP) interface, as shown in Figure B.3-4. It is responsible for delivering upstream frames to:
+
+- one or more downstream channels;
+- the MSAP interface.
+
+![Diagram of the MAC Forwarder architecture within a CM/MTS. The diagram shows the flow of data between the Host IP stack, RFI-NSI forwarding process, MAC Service Access Point (MSAP) interface, MAC Forwarder, Link security, and CM/MTS-NSI, all connected to Upstream and downstream channels.](ca5555bb37f54857199d243feff8479e_img.jpg)
+
+The diagram illustrates the internal architecture of a CM/MTS. At the top, two boxes represent the 'RFI-NSI forwarding process' and the 'Host IP stack, Incl. LLC and 802.2/DIX'. Both are connected to a thick horizontal line representing the 'MAC Service Access Point (MSAP) interface'. Below this interface is a dashed box labeled 'MAC'. Inside this box, the 'MAC Forwarder' and 'Link security' sublayers are shown. The 'MAC Forwarder' is connected to the MSAP interface and has bidirectional arrows pointing to the 'Link security' sublayer. The 'Link security' sublayer is connected to the 'Upstream and downstream channels' at the bottom. To the left of the MAC box, a 'CM/MTS-NSI' block is shown, which is also connected to the MSAP interface and has bidirectional arrows pointing to the 'Upstream and downstream channels'. The entire structure is enclosed in a dashed box labeled 'CM/MTS'. A small text 'T0906020-97/d050' is visible in the bottom right corner of the diagram area.
+
+Diagram of the MAC Forwarder architecture within a CM/MTS. The diagram shows the flow of data between the Host IP stack, RFI-NSI forwarding process, MAC Service Access Point (MSAP) interface, MAC Forwarder, Link security, and CM/MTS-NSI, all connected to Upstream and downstream channels.
+
+Figure B.3-4/J.112 – MAC Forwarder
+
+In Figure B.3-4, the LLC sublayer and link security sublayers of the upstream and downstream channels on the cable network terminate at the MAC Forwarder.
+
+The MSAP interface user MAY be the NSI-RFI Forwarding process or the CMTS's host protocol stack.
+
+Delivery of frames may be based on data-link-layer (bridging) semantics, network-layer (routing) semantics, or some combination. Higher-layer semantics may also be employed (e.g. filters on UDP port numbers). The CMTS MUST provide IP connectivity between hosts attached to cable modems, and must do so in a way that meets the expectations of Ethernet-attached customer equipment. For example, the CMTS must either forward ARP packets or it must facilitate a proxy ARP service. The CMTS MAC Forwarder MAY provide service for non-IP protocols.
+
+Note that there is no requirement that all upstream and downstream channels be aggregated under one MSAP as shown above. The vendor could just as well choose to implement multiple MSAPs, each with a single upstream and downstream channel.
+
+#### **B.3.2.1 Example rules for Data-Link-Layer forwarding**
+
+If the MAC Forwarder is implemented using only data-link-layer semantics, then the requirements in this subclause apply.
+
+Delivery of frames is dependent on the Destination Address within the frame. The means of learning the location of each address is vendor-dependent, and MAY include:
+
+- transparent-bridging-like source-address learning and aging;
+- gleaning from MAC Registration Request messages;
+- administrative means.
+
+If the destination address of a frame is unicast, and that address is associated with a particular downstream channel, then the frame MUST be forwarded to that channel<sup>1</sup>.
+
+If the destination address of a frame is unicast, and that address is known to reside on the other (upper) side of the MSAP interface, then the frame MUST be delivered to the MSAP interface.
+
+If the destination address is broadcast, multicast<sup>2</sup>, or unknown, the frame MUST BE delivered to both the MSAP and to all downstream channels.
+
+Delivery rules are similar to those for transparent bridging:
+
+- Frames from a specific source to a particular destination MUST be delivered in order.
+- Frames MUST NOT be duplicated.
+- Frames that cannot be delivered in a timely fashion MUST be discarded.
+- The Frame Check Sequence SHOULD be preserved rather than regenerated.
+
+#### **B.3.3 Network Layer**
+
+As stated above, the purpose of the data-over-cable system is to transport IP traffic transparently through the system.
+
+The Network Layer protocol is the Internet Protocol (IP) version 4, as defined in RFC-791, and migrating to IP version 6.
+
+This annex imposes no requirements for reassembly of IP packets.
+
+#### **B.3.4 Above the Network Layer**
+
+The subscribers will be able to use the transparent IP capability as a bearer for higher-layer services. Use of these services will be transparent to the CM.
+
+---
+
+<sup>1</sup> Vendors may implement extensions, similar to static addresses in 802.1d/ISO 10038 bridging, that cause such frames to be filtered or handled in some other manner.
+
+<sup>2</sup> The all-CMTSs multicast address (see Appendix B.I) is an exception. 802.1d/ISO 10038 Spanning Tree Bridge PDUs must be forwarded.
+
+In addition to the transport of user data, there are several network management and operation capabilities which depend upon the Network Layer. These include:
+
+- SNMP (Simple Network Management Protocol, [RFC-1157]), for network management.
+- TFTP (Trivial File Transfer Protocol, [RFC-1350]), a file transfer protocol, for downloading software and configuration information.
+- DHCP (Dynamic Host Configuration Protocol, DHCP [RFC-1541]), a framework for passing configuration information to hosts on a TCP/IP network.
+- A security management protocol as defined in [MCNS2].
+
+### **B.3.5 Data Link Layer**
+
+The Data Link Layer is divided into sublayers in accordance with [IEEE 802], with the addition of Link-Layer security in accordance with [MCNS2] and [MCNS8]. The sublayers, from the top, are:
+
+- Logical Link Control (LLC) sublayer (Class 1 only);
+- Link-Layer security sublayer;
+- Media Access Control (MAC) sublayer.
+
+#### **B.3.5.1 LLC sublayer**
+
+The LLC sublayer MUST be provided in accordance with [ISO/IEC 10039]. Address resolution MUST be used as defined in [RFC-826]. The MAC-to-LLC service definition is specified in [ISO/IEC 10039].
+
+#### **B.3.5.2 Link-layer security sublayer**
+
+Link-layer security MUST be provided in accordance with [MCNS2] and [MCNS8].
+
+#### **B.3.5.3 MAC sublayer**
+
+The definition, in detail, of the MAC sublayer and associated interfaces is provided in B.6.
+
+The MAC sublayer defines a single transmitter for each downstream channel – the CMTS. All CMs listen to all frames transmitted on the downstream channel upon which they are registered and accept those where the destinations match the CM itself or CPEs reached via the CMCI port. CMs can communicate with other CMs only through the CMTS.
+
+The upstream channel is characterized by many transmitters (CMs) and one receiver (the CMTS). Time in the upstream channel is slotted, providing for Time Division Multiple Access at regulated time ticks. The CMTS provides the time reference and controls the allowed usage for each interval. Intervals may be granted for transmissions by particular CMs, or for contention by all CMs. CMs may contend to request transmission time. To a limited extent, CMs may also contend to transmit actual data. In both cases, collisions can occur and retries are used.
+
+Subclause B.6 describes the MAC-sublayer messages from the CMTS which direct the behaviour of the CMs on the upstream channel, as well as messaging from the CMs to the CMTS.
+
+##### **B.3.5.3.1 Overview**
+
+Some of the MAC protocol highlights include:
+
+- bandwidth allocation controlled by CMTS;
+- a stream of mini-slots in the upstream;
+- dynamic mix of contention- and reservation-based upstream transmit opportunities;
+- bandwidth efficiency through support of variable-length packets;
+- extensions provided for future support of ATM or other Data PDU;
+- class-of-service support;
+- Extensions provided for security at the Data Link layer;
+- Support for a wide range of data rates.
+
+### **B.3.5.3.2 MAC service definition**
+
+The MAC sublayer service definition is in Appendix B.IV.
+
+## **B.3.6 Physical layer**
+
+The Physical (PHY) layer is comprised of two sublayers:
+
+- Transmission Convergence sublayer (present in the downstream direction only).
+- Physical Media Dependent (PMD) sublayer.
+
+### **B.3.6.1 Downstream Transmission Convergence sublayer**
+
+The Downstream Transmission Convergence sublayer exists in the downstream direction only. It provides an opportunity for additional services over the physical-layer bitstream. These additional services might include, for example, digital video. Definition of any such additional services is beyond the scope of this annex.
+
+This sublayer is defined as a continuous series of 188-byte MPEG [ITU-T H.222.0] packets, each consisting of a 4-byte header followed by 184 bytes of payload. The header identifies the payload as belonging to the data-over-cable MAC. Other values of the header may indicate other payloads. The mixture of payloads is arbitrary and controlled by the CMTS.
+
+The Downstream Transmission Convergence sublayer is defined in B.5.
+
+### **B.3.6.2 PMD sublayer**
+
+#### **B.3.6.2.1 Overview**
+
+The PMD sublayer involves digitally modulated RF carriers on the analogue cable network.
+
+In the downstream direction, the PMD sublayer is based on [ITU-T J.83 B], with the exceptions called out in B.4.3.2, and includes these features:
+
+- 64 and 256 QAM modulation formats;
+- 6-MHz occupied spectrum coexists with all other signals on the cable plant;
+- concatenation of Reed-Solomon block code and Trellis code supports operation in a higher percentage of North American cable networks;
+- variable-depth interleaver supports both latency-sensitive and -insensitive data.
+
+The features in the upstream direction are as follows:
+
+- flexible and programmable CM under control of the CMTS;
+- frequency agility;
+- time division multiple access;
+- QPSK and 16 QAM modulation formats;
+- support of both fixed-frame and variable-length PDU formats;
+- multiple symbol rates;
+- programmable Reed-Solomon block coding;
+- programmable preambles.
+
+#### **B.3.6.2.2 Interface points**
+
+Three RF interface points are defined at the PMD sublayer:
+
+- a) downstream output on the CMTS;
+- b) upstream input on the CMTS;
+- c) cable in/out at the cable modem.
+
+Separate downstream output and upstream input interfaces on the CMTS are required for compatibility with typical downstream and upstream signal combining and splitting arrangements in headends.
+
+## **B.4 Physical media dependent sublayer specification**
+
+### **B.4.1 Scope**
+
+This specification defines the electrical characteristics and protocol for a Cable Modem (CM) and Cable Modem Termination System (CMTS). It is the intent of this specification to define an interoperable CM and CMTS such that any implementation of a CM can work with any CMTS. It is not the intent of this specification to imply any specific implementation.
+
+### **B.4.2 Upstream**
+
+#### **B.4.2.1 Overview**
+
+The upstream Physical Media Dependent (PMD) sublayer uses a FDMA/TDMA burst modulation format, which provides five symbol rates and two modulation formats (QPSK and 16QAM). The modulation format includes pulse shaping for spectral efficiency, is carrier-frequency agile, and has selectable output power level. The PMD sublayer format includes a variable-length modulated burst with precise timing beginning at boundaries spaced at integer multiples of 6.25 µs apart (which is 16 symbols at the highest data rate).
+
+Each burst supports a flexible modulation, symbol rate, preamble, randomization of the payload, and programmable FEC encoding.
+
+All of the upstream transmission parameters associated with burst transmission outputs from the CM are configurable by the CMTS via MAC messaging. Many of the parameters are programmable on a burst-by-burst basis.
+
+The PMD sublayer can support a near-continuous mode of transmission, wherein ramp-down of one burst MAY overlap the ramp-up of the following burst, so that the transmitted envelope is never zero. The system timing of the TDMA transmissions from the various CMs MUST provide that the centre of the last symbol of one burst and the centre of the first symbol of the preamble of an immediately following burst are separated by at least the duration of five symbols. The guard time MUST be greater than or equal to the duration of five symbols plus the maximum timing error. Timing error is contributed by both the CM and CMTS. CM timing performance is specified in B.4. Maximum timing error and guard time may vary with CMTSs from different vendors.
+
+The upstream modulator is part of the cable modem which interfaces with the cable network. The modulator contains the actual electrical-level modulation function and the digital signal-processing function; the latter provides the FEC, preamble prepend, symbol mapping, and other processing steps. This specification is written with the idea of buffering the bursts in the signal processing portion, and with the signal processing portion:
+
+- 1) accepting the information stream a burst at a time;
+- 2) processing this stream into a complete burst of symbols for the modulator; and
+- 3) feeding the properly-timed bursted symbol stream to a memoryless modulator at the exact burst transmit time.
+
+The memoryless portion of the modulator only performs pulse shaping and quadrature upconversion.
+
+At the Demodulator, similar to the Modulator, there are two basic functional components: the demodulation function and the signal processing function. Unlike the Modulator, the Demodulator resides in the CMTS and the specification is written with the concept that there will be one demodulation function (not necessarily an actual physical demodulator) for each carrier frequency in use. The demodulation function would receive all bursts on a given frequency.
+
+NOTE – The unit design approach should be cognizant of the multiple-channel nature of the demodulation and signal processing to be carried out at the headend, and partition/share functionality appropriately to optimally leverage the multi-channel application. A Demodulator design supporting multiple channels in a Demodulator unit may be appropriate.
+
+The demodulation function of the Demodulator accepts a varying-level signal centred around a commanded power level and performs symbol timing and carrier recovery and tracking, burst acquisition, and demodulation. Additionally, the demodulation function provides an estimate of burst timing relative to a reference edge, an estimate of received signal power, an estimate of signal-to-noise ratio, and may engage adaptive equalization to mitigate the effects of:
+
+- a) echoes in the cable plant;
+- b) narrowband ingress; and
+- c) group delay.
+
+The signal-processing function of the Demodulator performs the inverse processing of the signal-processing function of the Modulator. This includes accepting the demodulated burst data stream and decoding, etc., and possibly multiplexing the data from multiple channels into a single output stream. The signal-processing function also provides the edge-timing reference and gating-enable signal to the demodulators to activate the burst acquisition for each assigned burst slot. The signal-processing function may also provide an indication of successful decoding, decoding error, or fail-to-decode for each code word and the number of corrected Reed-Solomon symbols in each code word. For every upstream burst, the CMTS has a prior knowledge of the exact burst length in symbols (see B.4.2.6, B.4.2.10.1 and B.I.2).
+
+#### **B.4.2.2 Modulation formats**
+
+The upstream modulator MUST provide both QPSK and 16 QAM modulation formats.
+
+The upstream demodulator MUST support QPSK, 16 QAM, or both modulation formats.
+
+##### **B.4.2.2.1 Modulation rates**
+
+The upstream modulator MUST provide QPSK at 160, 320, 640, 1280, and 2560 ksym/s, and 16 QAM at 160, 320, 640, 1280, and 2560 ksym/s.
+
+This variety of modulation rates, and flexibility in setting upstream carrier frequencies, permits operators to position carriers in gaps in the pattern of narrowband ingress, as discussed in Appendix B.VI.
+
+The upstream symbol rate MUST be fixed for each upstream frequency.
+
+##### **B.4.2.2.2 Symbol mapping**
+
+The modulation mode (QPSK or 16 QAM) is programmable. The symbols transmitted in each mode and the mapping of the input bits to the I and Q constellation MUST be as defined in Table B.4-1. In the table,  $I_1$  is the MSB of the symbol map,  $Q_1$  is the LSB for QPSK, and  $Q_0$  is the LSB for 16 QAM.  $Q_1$  and  $I_0$  have intermediate bit positions in 16 QAM. The MSB MUST be the first bit in the serial data into the symbol mapper.
+
+**Table B.4-1/J.112 – I/Q mapping**
+
+| <b>QAM mode</b> | <b>Input bit definitions</b> |
+|-----------------|------------------------------|
+| QPSK            | $I_1 Q_1$                    |
+| 16 QAM          | $I_1 Q_1 I_0 Q_0$            |
+
+The upstream QPSK symbol mapping MUST be as shown in Figure B.4-1.
+
+![QPSK symbol mapping diagram showing four quadrants with bit pairs 01, 11, 00, and 10.](fc7ea02351e757da3b2a8d1a49565e31_img.jpg)
+
+A diagram of the QPSK symbol mapping. It features a vertical axis labeled  $Q_1$  and a horizontal axis labeled  $I_1$ . The four quadrants contain the following bit pairs:
+
+|    |    |
+|----|----|
+| 01 | 11 |
+| 00 | 10 |
+
+T0904800-97/d051
+
+QPSK symbol mapping diagram showing four quadrants with bit pairs 01, 11, 00, and 10.
+
+**Figure B.4-1/J.112 – QPSK symbol mapping**
+
+The 16 QAM non-inverted (Gray-coded) symbol mapping MUST be as shown in Figure B.4-2.
+
+![16 QAM Gray-coded symbol mapping diagram showing a 4x4 grid of 16 symbols.](0e0257d43c47df039e9755c59674c2e5_img.jpg)
+
+A diagram of the 16 QAM Gray-coded symbol mapping. It features a vertical axis labeled  $Q$  and a horizontal axis labeled  $I$ . The symbols are arranged in a 4x4 grid as follows:
+
+|      |      |      |      |
+|------|------|------|------|
+| 0111 | 0101 | 1101 | 1111 |
+| 0110 | 0100 | 1100 | 1110 |
+| 0010 | 0000 | 1000 | 1010 |
+| 0011 | 0001 | 1001 | 1011 |
+
+T0904810-97/d052
+
+16 QAM Gray-coded symbol mapping diagram showing a 4x4 grid of 16 symbols.
+
+**Figure B.4-2/J.112 – 16 QAM Gray-coded symbol mapping**
+
+The 16 QAM differential symbol mapping MUST be as shown in Figure B.4-3.
+
+![Figure B.4-3/J.112 – 16 QAM differential-coded symbol mapping. A constellation diagram showing 16 points in a 4x4 grid on an I-Q plane. The points are labeled with 5-bit binary sequences. The quadrants are: Top-Left (0111, 0110, 0101, 0100), Top-Right (1101, 1111, 1100, 1110), Bottom-Left (0010, 0000, 0011, 0001), and Bottom-Right (1000, 1001, 1010, 1011). The axes are labeled I (horizontal) and Q (vertical). A small text 'T0904820-97/d053' is at the bottom right.](141be2c164b6aa7704c470b47023de6c_img.jpg)
+
+Figure B.4-3/J.112 – 16 QAM differential-coded symbol mapping. A constellation diagram showing 16 points in a 4x4 grid on an I-Q plane. The points are labeled with 5-bit binary sequences. The quadrants are: Top-Left (0111, 0110, 0101, 0100), Top-Right (1101, 1111, 1100, 1110), Bottom-Left (0010, 0000, 0011, 0001), and Bottom-Right (1000, 1001, 1010, 1011). The axes are labeled I (horizontal) and Q (vertical). A small text 'T0904820-97/d053' is at the bottom right.
+
+Figure B.4-3/J.112 – 16 QAM differential-coded symbol mapping
+
+If differential quadrant encoding is enabled, then the currently-transmitted symbol quadrant is derived from the previously-transmitted symbol quadrant and the current input bits via Table B.4-2.
+
+Table B.4-2/J.412 – Derivation of currently-transmitted symbol quadrant
+
+| Current input bits<br>I(1) Q(1) | Quadrant<br>phase change | MSBs of previously<br>transmitted symbol | MSBs for currently<br>transmitted symbol |
+|---------------------------------|--------------------------|------------------------------------------|------------------------------------------|
+| 00                              | 0°                       | 11                                       | 11                                       |
+| 00                              | 0°                       | 01                                       | 01                                       |
+| 00                              | 0°                       | 00                                       | 00                                       |
+| 00                              | 0°                       | 10                                       | 10                                       |
+| 01                              | 90°                      | 11                                       | 01                                       |
+| 01                              | 90°                      | 01                                       | 00                                       |
+| 01                              | 90°                      | 00                                       | 10                                       |
+| 01                              | 90°                      | 10                                       | 11                                       |
+| 11                              | 180°                     | 11                                       | 00                                       |
+| 11                              | 180°                     | 01                                       | 10                                       |
+| 11                              | 180°                     | 00                                       | 11                                       |
+| 11                              | 180°                     | 10                                       | 01                                       |
+| 10                              | 270°                     | 11                                       | 10                                       |
+| 10                              | 270°                     | 01                                       | 11                                       |
+| 10                              | 270°                     | 00                                       | 01                                       |
+| 10                              | 270°                     | 10                                       | 00                                       |
+
+#### B.4.2.2.3 Spectral shaping
+
+The upstream PMD sublayer MUST support a 25% Nyquist square root raised cosine shaping.
+
+The occupied spectrum MUST NOT exceed the channel widths shown in Table B.4-3.
+
+**Table B.4-3/J.112 – Maximum channel width**
+
+| Symbol rate (ksym/s)                                 | Channel width (kHz) <sup>a)</sup> |
+|------------------------------------------------------|-----------------------------------|
+| 160                                                  | 200                               |
+| 320                                                  | 400                               |
+| 640                                                  | 800                               |
+| 1280                                                 | 1600                              |
+| 2560                                                 | 3200                              |
+| <sup>a)</sup> Channel width is the –30 dB bandwidth. |                                   |
+
+#### B.4.2.2.4 Upstream frequency agility and range
+
+The upstream PMD sublayer MUST support operation over the frequency range of 5-42 MHz edge-to-edge.
+
+Offset frequency resolution MUST be supported having a range of  $\pm 32$  kHz (increment = 1 Hz; implement within  $\pm 10$  Hz).
+
+#### B.4.2.2.5 Spectrum format
+
+The upstream modulator MUST provide operation with the format  $s(t) = I(t) * \cos(\omega t) - Q(t) * \sin(\omega t)$ , where  $t$  denotes time and  $\omega$  denotes angular frequency.
+
+### B.4.2.3 FEC Encode
+
+#### B.4.2.3.1 FEC Encode modes
+
+The upstream modulator MUST be able to provide the following selections: Reed-Solomon codes over GF(256) with  $T = 1$  to 10 or no FEC coding.
+
+The following Reed-Solomon generator polynomial MUST be supported:
+
+$$g(x) = (x + \alpha^0)(x + \alpha^1)\dots(x + \alpha^{2T-1})$$
+
+where the primitive element alpha is 0x02 hex
+
+The following Reed-Solomon primitive polynomial MUST be supported:
+
+$$p(x) = x^8 + x^4 + x^3 + x^2 + 1$$
+
+The upstream modulator MUST provide code words from a minimum size of 18 bytes (16 information bytes [ $k$ ] plus two parity bytes for  $T = 1$  error correction) to a maximum size of 255 bytes ( $k$ -bytes plus parity-bytes). The uncoded word size can have a minimum of one byte.
+
+In Shortened Last Code Word mode, the CM MUST provide the last code word of a burst shortened from the assigned length of  $k$  data bytes per code word as described in B.4.2.10.1.2.
+
+The value of  $T$  MUST be configured in response to the Upstream Channel Descriptor from the CMTS.
+
+### B.4.2.3.2 FEC Bit-to-symbol ordering
+
+The input to the Reed-Solomon Encoder is logically a serial bit stream from the MAC layer of the CM, and the first bit of the stream MUST be mapped into the MSB of the first Reed-Solomon symbol into the encoder. The MSB of the first symbol out of the encoder MUST be mapped into the first bit of the serial bit stream fed to the Scrambler.
+
+Note that the MAC byte-to-serial upstream convention calls for the byte LSB to be mapped into the first bit of the serial bit stream per B.6.2.1.3.
+
+### B.4.2.4 Scrambler (Randomizer)
+
+The upstream modulator MUST implement a scrambler (shown in Figure B.4-4) where the 15-bit seed value MUST be arbitrarily programmable.
+
+At the beginning of each burst, the register is cleared and the seed value is loaded. The seed value MUST be used to calculate the scrambler bit which is combined in an XOR with the first bit of data of each burst (which is the MSB of the first symbol following the last symbol of the preamble).
+
+The scrambler seed value MUST be configured in response to the Upstream Channel Descriptor from the CMTS.
+
+The polynomial MUST be  $x^{15} + x^{14} + 1$ .
+
+![Figure B.4-4/J.112 – Scrambler structure diagram. The diagram shows a 15-bit shift register (Delay elements 1 to N) initialized by Seed LSB and Seed MSB inputs via a Seedload/Frame reset line. The output of Delay element N (N=15) is XORed with the Randomizer data input to produce the Randomizer data output. The output is also fed back through a series of delay elements (1, 2, 3, ..., N-2, N-1) to generate the scrambling sequence.](6322885569221ec51d70560d7dba1339_img.jpg)
+
+The diagram illustrates the internal structure of a scrambler. At the top, a 'Seedload/Frame reset' input is connected to the initialization of a 15-bit shift register. The register is composed of 'Delay element 1', 'Delay element 2', 'Delay element 3', followed by a gap (indicated by dashed lines), then 'Delay element N-2', 'Delay element N-1', and finally 'Delay element N'. The 'Seed LSB' is input to the first delay element, and the 'Seed MSB' is input to the last delay element. The output of 'Delay element N' is labeled 'N = 15'. This output is connected to an 'XOR' gate (represented by a circle with an 'X'). The other input to this 'XOR' gate is the 'Randomizer data input'. The output of this 'XOR' gate is the 'Randomizer data output'. This output is also fed back into the 'Delay element 1' to complete the shift register loop. A second 'XOR' gate is shown at the bottom, which performs the XOR operation between the 'Randomizer data input' and the feedback signal from the shift register to produce the final 'Randomizer data output'.
+
+Figure B.4-4/J.112 – Scrambler structure diagram. The diagram shows a 15-bit shift register (Delay elements 1 to N) initialized by Seed LSB and Seed MSB inputs via a Seedload/Frame reset line. The output of Delay element N (N=15) is XORed with the Randomizer data input to produce the Randomizer data output. The output is also fed back through a series of delay elements (1, 2, 3, ..., N-2, N-1) to generate the scrambling sequence.
+
+Figure B.4-4/J.112 – Scrambler structure
+
+### B.4.2.5 Preamble prepend
+
+The upstream PMD sublayer MUST support a variable-length preamble field that is prepended to the data after they have been randomized and Reed-Solomon encoded.
+
+The first bit of the Preamble Pattern is the first bit into the symbol mapper (see Figure B.4-8), and is  $I_1$  in the first symbol of the burst (see B.4.2.2.2). The first bit of the Preamble Pattern is designated by the Preamble Value Offset as described in Table B.6-15, B.6.3.2.2.
+
+The value of the preamble that is prepended MUST be programmable and the length MUST be 0, 2, 4, ..., or 1024 bits for QPSK and 0, 4, 8, ..., or 1024 bits for 16 QAM. Thus, the maximum length of the preamble is 512 QPSK symbols or 256 QAM symbols.
+
+The preamble length and value MUST be configured in response to the Upstream Channel Descriptor message transmitted by the CMTS.
+
+#### B.4.2.6 Burst profiles
+
+The transmission characteristics are separated into three portions:
+
+- a) Channel parameters;
+- b) Burst Profile attributes; and
+- c) User Unique parameters.
+
+The Channel parameters include:
+
+- i) the symbol rate (five rates from 160 ksym/s to 2.56 Msym/s in octave steps);
+- ii) the center frequency (Hz); and
+- iii) the 1024-bit Preamble Superstring.
+
+The Channel parameters are further described in B.6.3.2.2, Table B.6-14; these characteristics are shared by all users on a given channel. The Burst Profile Attributes are listed in Table B.4-4, and are further described in B.6.3.2.2, Table B.6-15; these parameters are the shared attributes corresponding to a burst type. The User Unique Parameters may vary for each user even when using the same burst type on the same channel as another user (for example, Power Level) and are listed in Table B.4-5.
+
+**Table B.4-4/J.112 – Burst Profile attributes**
+
+| Burst Parameter attributes                                                                                                                                                                                                           | Configuration settings                                                    |
+|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------|
+| Modulation                                                                                                                                                                                                                           | QPSK, 16 QAM                                                              |
+| Diff Enc                                                                                                                                                                                                                             | On/Off                                                                    |
+| Preamble Length                                                                                                                                                                                                                      | 0-1024 bits (B.4.2.5)                                                     |
+| Preamble Value offset                                                                                                                                                                                                                | 0 to 1022                                                                 |
+| FEC Error Correction (T bytes)                                                                                                                                                                                                       | 0 to 10 (0 implies FEC = off)                                             |
+| FEC Code word Information Bytes (k)                                                                                                                                                                                                  | Fixed: 16 to 253 (assuming FEC on) Shortened: 16 to 253 (assuming FEC on) |
+| Scrambler Seed                                                                                                                                                                                                                       | 15 bits                                                                   |
+| Maximum Burst Length (minislots) (Note)                                                                                                                                                                                              | 0 to 255                                                                  |
+| Guard Time                                                                                                                                                                                                                           | 5 to 255 Symbols                                                          |
+| Last Code word Length                                                                                                                                                                                                                | Fixed, shortened                                                          |
+| Scrambler On/Off                                                                                                                                                                                                                     | On/Off                                                                    |
+| NOTE – A burst length of 0 mini-slots in the Channel Profile means that the burst length is variable on that channel for that burst type. The burst length, while not fixed, is granted explicitly by the CMTS to the CM in the MAP. |                                                                           |
+
+**Table B.4-5/J.112 – User Unique Burst parameters**
+
+| User Unique parameter                                                          | Configuration settings                                               |
+|--------------------------------------------------------------------------------|----------------------------------------------------------------------|
+| Power Level (Note)                                                             | +8 to +55 dBmV (16 QAM)<br>+8 to +58 dBmV (QPSK)<br>1 –dB steps      |
+| Offset Frequency (Note)                                                        | Range = $\pm 32$ kHz; increment = 1 Hz; implement within $\pm 10$ Hz |
+| Ranging Offset                                                                 | 0 to $(2^{16} - 1)$ , increments of 6.25 $\mu$ sec/64                |
+| Burst Length (mini-slots) if variable on this channel (changes burst-to-burst) | 1 to 255 mini-slots                                                  |
+| Transmit Equalizer Coefficients (Note) (advanced modems only)                  | Up to 64 coefficients; 4 bytes per coefficient: 2 real and 2 complex |
+| NOTE – Values in table apply for this given channel and symbol rate.           |                                                                      |
+
+The CM MUST generate each burst at the appropriate time as conveyed in the mini-slot grants provided by the CMTS MAPs (see B.6.3.2.3).
+
+The CM MUST support all burst profiles commanded by the CMTS via the Burst Descriptors in the UCD (see B.6.3.2.2), and subsequently assigned for transmission in a MAP (see B.6.3.2.3).
+
+The CM MUST implement the Offset Frequency to within  $\pm 10$  Hz.
+
+Ranging Offset is the delay correction applied by the CM to the CMTS Upstream Frame Time derived at the CM, in order to synchronize the upstream transmissions in the TDMA scheme. The Ranging Offset is an advancement equal to roughly the round-trip delay of the CM from the CMTS. The CMTS MUST provide feedback correction for this offset to the CM, based on reception of one or more successfully received bursts (i.e. satisfactory result from each technique employed: error correction and/or CRC), with accuracy within 1/2 symbol and resolution of 1/64 of the frame tick increment ( $6.25 \mu\text{s}/64 = 0.09765625 \mu\text{s} = 1/4$  the symbol duration of the highest symbol rate =  $10.24 \text{ MHz}^{-1}$ ). The CMTS sends adjustments to the CM, where a negative value implies the Ranging Offset is to be decreased, resulting in later times of transmission at the CM. CM MUST implement the correction with resolution of at most 1 symbol duration (of the symbol rate in use for a given burst), and (other than a fixed bias) with accuracy within  $\pm 0.25 \mu\text{s}$  plus  $\pm 1/2$  symbol owing to resolution. The accuracy of CM burst timing of  $\pm 0.25 \mu\text{s}$  plus  $\pm 1/2$  symbol is relative to the mini-slot boundaries derivable at the CM based on an ideal processing of the timestamp signals received from the CMTS.
+
+The CM MUST be capable of switching burst profiles with no reconfiguration time required between bursts except for changes in the following parameters:
+
+- 1) Output Power;
+- 2) Modulation;
+- 3) Symbol Rate;
+- 4) Offset frequency;
+- 5) Channel Frequency; and
+- 6) Ranging Offset.
+
+For Symbol Rate, Offset frequency and Ranging Offset, the CM MUST be able to transmit consecutive bursts as long as the CMTS allocates at least 96 symbols in between the last symbol centre of one burst and the first symbol centre of the following burst. The maximum reconfiguration time of 96 symbols should compensate for the ramp down time of one burst and the ramp up time of the next burst as well as the overall transmitter delay time including the pipeline delay and optional pre-equalizer delay. For modulation type changes, the CM MUST be able to transmit consecutive bursts as long as the CMTS allocates at least 96 symbols in between the last symbol centre of one burst and the first symbol centre of the following burst. Output Power, Symbol Rate, Offset frequency, Channel Frequency and Ranging Offset MUST NOT be changed until the CM is provided sufficient time between bursts by the CMTS. Transmitted Output Power, Symbol Rate, Offset frequency, Channel Frequency and Ranging Offset MUST NOT change while more than  $-30$  dB of any symbol's energy of the previous burst remains to be transmitted, or more than  $-30$  dB of any symbol's energy of the next burst has been transmitted. The modulation MUST NOT change while more than  $-30$  dB of any symbol's energy of the previous burst remains to be transmitted, or more than  $-30$  dB of any symbol's energy of the next burst has been transmitted, EXCLUDING the effect of the transmit equalizer (if present in the CM). (This is to be verified with the transmit equalizer providing no filtering; delay only, if that. Note that if the CMTS has decision feedback in its equalizer, it may need to provide more than the 96 symbol gap between bursts of different modulation type which the same CM may use; this is a CMTS decision.) Negative ranging offset adjustments will cause the 96 symbol guard to be violated. The CMTS must assure that this does not happen by allowing extra guard time between bursts that is at least equal to the amount of negative ranging offset.
+
+If Channel Frequency is to be changed, then the CM MUST be able to implement the change between bursts as long as the CMTS allocates at least 96 symbols plus 100 ms between the last symbol centre of one burst and the first symbol of the following burst.
+
+The Channel Frequency of the CM MUST be settled within the phase noise and accuracy requirements of B.4.2.9.5 and B.4.2.9.6 within 100 ms from the beginning of the change.
+
+If Output Power is to be changed by 1 dB or less, then the CM MUST be able to implement the change between bursts as long as the CMTS allocates at least 96 symbols plus 5  $\mu$ s between the last symbol centre of one burst and the first symbol centre of the following burst.
+
+If Output Power is to be changed by more than 1 dB, then the CM MUST be able to implement the change between bursts as long as the CMTS allocates at least 96 symbols plus 10  $\mu$ s between the last symbol centre of one burst and the first symbol centre of the following burst.
+
+The Output Power of the CM MUST be settled to within  $\pm 0.1$  dB of its final output power level:
+
+- a) within 5  $\mu$ s from the beginning of a change of 1 dB or less; and
+- b) within 10  $\mu$ s from the beginning of a change of greater than 1 dB.
+
+The output transmit power MUST be maintained constant within a TDMA burst to within less than 0.1 dB (excluding the amount theoretically present due to pulse shaping, and amplitude modulation in the case of 16 QAM).
+
+#### **B.4.2.7 Burst timing convention**
+
+Figure B.4-5 illustrates the nominal burst timing.
+
+Figure B.4-6 indicates worst-case burst timing. In this example, burst N arrives 1.5 symbols late, and burst N + 1 arrives 1.5 symbols early, but separation of 5 symbols is maintained; 8-symbol guard band shown.
+
+At a symbol rate of  $R_s$ , symbols occur at a rate of one each  $T_s = 1/R_s$  seconds. Ramp up and Ramp down are the spread of a symbol in the time domain beyond  $T_s$  duration owing to the symbol-shaping filter. If only one symbol were transmitted, its duration would be longer than  $T_s$  due to the shaping filter impulse response being longer than  $T_s$ . The spread of the first and last symbols of a burst transmission effectively extends the duration of the burst to longer than  $N * T_s$ , where N is the number of symbols in the burst.
+
+#### **B.4.2.8 Transmit power requirements**
+
+The upstream PMD sublayer MUST support varying the amount of transmit power. Requirements are presented for:
+
+- 1) the range of commanded transmit power;
+- 2) the step size of the power commands; and
+- 3) the accuracy (actual output power compared to the commanded amount) of the response to the command.
+
+The mechanism by which power adjustments are performed is defined in B.7.2.5. Such adjustments MUST be within the ranges of tolerances described below.
+
+##### **B.4.2.8.1 Output power agility and range**
+
+The output transmit power in the design bandwidth MUST be variable over the range of +8 dBmV to 55 dBmV (16 QAM), or 58 dBmV (QPSK), in 1-dB steps.
+
+The absolute accuracy of the transmitted power MUST be  $\pm 2$  dB, and the step size accuracy  $\pm 0.4$  dB, with an allowance for hysteresis while switching in/out a step attenuator (e.g. 20 dB) in which case the accuracy requirement is relaxed to  $\pm 1.4$  dB. For example, the actual power increase resulting from a command to increase the power level by 1 dB in a CM's next transmitted burst MUST be between 0.6 and 1.4 dB.
+
+The step resolution MUST be 1 dB or less. When a CM is commanded with finer resolution than it can implement, it MUST round to the nearest supported step size. If the commanded step is half way between two supported step sizes, the CM MUST choose the smaller step. For example, with a supported step resolution of 1 dB, a command to step  $\pm 0.5$  dB would result in no step, while a command to step  $\pm 0.75$  dB would result in a  $\pm 1$  dB step.
+
+![Diagram of nominal burst timing showing two bursts, N and N+1. Burst N includes a ramp up, preamble, data, and ramp down. Burst N+1 starts with a preamble. Timing is referenced to the center of the first preamble symbol. A 10-symbol ramp duration and an 8-symbol guard band are indicated.](0f9ac2696d8775f168c8a2236752ca85_img.jpg)
+
+a) Nominal burst profile (no timing errors); 8-symbol guard band is illustrated; 10-symbol ramp up and ramp down is illustrated.
+
+Diagram a) shows a single burst profile with the following components and labels:
+
+- Ramp up**: The initial rising edge of the burst.
+- Preamble first symbol**: The start of the preamble sequence.
+- Preamble last symbol**: The end of the preamble sequence.
+- Data first symbol**: The start of the data payload.
+- Last FEC parity symbol**: The end of the data payload.
+- Ramp down**: The final falling edge of the burst.
+
+Diagram b) illustrates the timing reference and the relationship between consecutive bursts:
+
+- Timing is referenced to the symbol centre of the first symbol of each burst**: This is indicated by a vertical dashed line from the 'Centre of preamble First symbol'.
+- Centre of preamble First symbol = Mini-slot boundary**: This point defines the start of a mini-slot.
+- 10 symbols**: The duration of the ramp up and ramp down phases.
+- 8 symbols**: The guard band duration between the end of one burst's data and the start of the next burst's preamble.
+- Mini-slot boundary**: The start of the next burst's preamble.
+- Burst N** and **Burst N + 1**: Two consecutive bursts.
+- Preamble first symbol**: The start of the preamble for Burst N + 1.
+
+T0904840-97/d055
+
+Diagram of nominal burst timing showing two bursts, N and N+1. Burst N includes a ramp up, preamble, data, and ramp down. Burst N+1 starts with a preamble. Timing is referenced to the center of the first preamble symbol. A 10-symbol ramp duration and an 8-symbol guard band are indicated.
+
+NOTE – Ramp down of one burst can overlap ramp up of following burst even with one transmitter assigned both bursts.
+
+Figure B.4-5/J.112 – Nominal burst timing
+
+![Figure B.4-6/J.112 – Worst-case burst timing diagram. The diagram shows two bursts, Burst N and Burst N+1, with their symbol centers and timing parameters. Burst N is shown with a decreasing envelope, and Burst N+1 is shown with an increasing envelope. The diagram includes labels for 'Worst-case burst timing input to CMTS', 'Burst N', 'Burst N + 1', 'Symbol centre of Burst N, last symbol; 1.5 symbols late', 'Symbol centre of Burst N + 1, last symbol; 1.5 symbols early', 'Time equal to 5 symbols separates the first symbol centre of burst N + 1 and the last symbol centre of burst N', '8-symbol guard band', '1.5', '5 symbols', and 'Mini-slot boundary'. A reference code 'T0904850-97/d056' is also present.](3349dc82c6333221b0610be6ee7250b6_img.jpg)
+
+Worst-case burst timing input to CMTS
+
+Burst N + 1
+
+Burst N
+
+Symbol centre of Burst N, last symbol; 1.5 symbols late
+
+Symbol centre of Burst N + 1, last symbol; 1.5 symbols early
+
+Time equal to 5 symbols separates the first symbol centre of burst N + 1 and the last symbol centre of burst N
+
+8-symbol guard band
+
+1.5
+
+5 symbols
+
+Mini-slot boundary
+
+T0904850-97/d056
+
+Figure B.4-6/J.112 – Worst-case burst timing diagram. The diagram shows two bursts, Burst N and Burst N+1, with their symbol centers and timing parameters. Burst N is shown with a decreasing envelope, and Burst N+1 is shown with an increasing envelope. The diagram includes labels for 'Worst-case burst timing input to CMTS', 'Burst N', 'Burst N + 1', 'Symbol centre of Burst N, last symbol; 1.5 symbols late', 'Symbol centre of Burst N + 1, last symbol; 1.5 symbols early', 'Time equal to 5 symbols separates the first symbol centre of burst N + 1 and the last symbol centre of burst N', '8-symbol guard band', '1.5', '5 symbols', and 'Mini-slot boundary'. A reference code 'T0904850-97/d056' is also present.
+
+Figure B.4-6/J.112 – Worst-case burst timing
+
+#### B.4.2.9 Fidelity requirements
+
+##### B.4.2.9.1 Spurious emissions
+
+The noise and spurious power MUST NOT exceed the levels given in Tables B.4-6, B.4-7 and B.4-8.
+
+In Table B.4-6, In-band spurious includes noise, carrier leakage, clock lines, synthesizer spurious products, and other undesired transmitter products. It does not include ISI. The measurement bandwidth for In-band spurious is equal to the symbol rate (e.g. 160 kHz for 160 ksymb/s).
+
+The measurement bandwidth for the 3 (or fewer) Carrier-Related Frequency Bands (below 42 MHz) is 160 kHz, with up to 3 is 160 kHz bands, each with no more than –47 dBc, allowed to be excluded from the "Bands within 5 to 42 MHz Transmitting Burst" specs of Table B.4-8.
+
+The measurement bandwidth is also 160 kHz for the Between bursts specs of Table B.4-6 below 42 MHz; the Transmitting burst specs apply during the mini-slots granted to the CM (when the CM uses all or a portion of the grant), and for a mini-slot before and after the granted mini-slots. (Note that a mini-slot may be as short as 32 symbols, or 12.5 µs at the 2.56 Msym/s rate, or as short as 200 µs at the 160 ksym/s rate.) The Between bursts specs apply except during a used grant of mini-slots, and the mini-slot before and after the used grant.
+
+**Table B.4-6/J.112 – Spurious emissions**
+
+| Parameter                                                                                                                                                                                              | Transmitting burst                                        | Between bursts                                                         |
+|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------|------------------------------------------------------------------------|
+| In-band [In-band spurious includes noise, carrier leakage, clock lines, synthesizer spurious products, and other undesired transmitter products. It does not include Inter Symbol Interference (ISI)]. | –40 dBc                                                   | The greater of –72 dBc or –59 dBmV                                     |
+| Adjacent Band                                                                                                                                                                                          | See Table B.4-7                                           | The greater of –72 dBc or –59 dBmV                                     |
+| 3 or Fewer Carrier-Related Frequency Bands (such as second harmonic, if < 42 MHz)                                                                                                                      | –47 dBc                                                   | The greater of –72 dBc or –59 dBmV                                     |
+| Bands within 5 to 42 MHz (excluding assigned channel, adjacent channels, and carrier-related channels)                                                                                                 | See Table B.4-8                                           | The greater of –72 dBc or –59 dBmV                                     |
+| CM Integrated Spurious Emissions Limits (all in 4 MHz, includes discrete <sup>a)</sup> )<br>42 to 54 MHz<br>54 to 60 MHz<br>60 to 88 MHz<br>88 to 860 MHz                                              | max –40 dBc, –26 dBmV<br>–35 dBmV<br>–40 dBmV<br>–45 dBmV | –26 dBmV<br>–40 dBmV<br>–40 dBc<br>max –45 dBmV, –40 dBc <sup>b)</sup> |
+| CM Discrete Spurious Emissions Limits <sup>a)</sup><br>42 to 54 MHz<br>54 to 88 MHz<br>88 to 860 MHz                                                                                                   | max –50 dBc, –36 dBmV<br>–50 dBmV<br>–50 dBmV             | –36 dBmV<br>–50 dBmV<br>–50 dBmV                                       |
+
+a) These spec limits exclude a single discrete spur related to the tuned received channel; this single discrete spur MUST be no greater than –40 dBmV.
+
+b) 'dBc' is relative to the received downstream signal level. Some spurious outputs are proportional to the receive signal level.
+
+#### B.4.2.9.1.1 Adjacent channel spurious emissions
+
+Spurious emissions from a transmitted carrier may occur in an adjacent channel which could be occupied by a carrier of the same or different symbol rates. Table B.4-7 lists the required adjacent channel spurious emission levels for all combinations of transmitted carrier symbol rates and adjacent channel symbol rates. The measurement is performed in an adjacent channel interval that is of appropriate bandwidth and distance from the transmitted carrier based on the symbol rates of the transmitted carrier and the carrier in the adjacent channel.
+
+**Table B.4-7/J.112 – Adjacent channel spurious emissions**
+
+| Transmitted carrier symbol rate | Specification in the interval | Measurement interval and distance from carrier edge | Adjacent channel carrier symbol rate |
+|---------------------------------|-------------------------------|-----------------------------------------------------|--------------------------------------|
+| 160 Ksym/s                      | –45 dBc                       | 20 to 180 kHz                                       | 160 ksym/s                           |
+|                                 | –45 dBc                       | 40 to 360 kHz                                       | 320 ksym/s                           |
+|                                 | –45 dBc                       | 80 to 720 kHz                                       | 640 ksym/s                           |
+|                                 | –42 dBc                       | 160 to 1440 kHz                                     | 1280 ksym/s                          |
+|                                 | –39 dBc                       | 320 to 2880 kHz                                     | 2560 ksym/s                          |
+| All other symbol rates          | –45 dBc                       | 20 to 180 kHz                                       | 160 ksym/s                           |
+|                                 | –45 dBc                       | 40 to 360 kHz                                       | 320 ksym/s                           |
+|                                 | –45 dBc                       | 80 to 720 kHz                                       | 640 ksym/s                           |
+|                                 | –44 dBc                       | 160 to 1440 kHz                                     | 1280 ksym/s                          |
+|                                 | –41 dBc                       | 320 to 2880 kHz                                     | 2560 ksym/s                          |
+
+#### B.4.2.9.1.2 Spurious emissions in 5 to 42 MHz
+
+Spurious emissions, other than those in an adjacent channel or carrier related emissions listed above, may occur in intervals that could be occupied by other carriers of the same or different symbol rates. To accommodate these different symbol rates and associated bandwidths, the spurious emissions are measured in an interval equal to the bandwidth corresponding to the symbol rate of the carrier that could be transmitted in that interval. This interval is independent of the current transmitted symbol rate.
+
+Table B.4-8 lists the possible symbol rates that could be transmitted in an interval, the required spurious level in that interval, and the initial measurement interval at which to start measuring the spurious emissions. Measurements should start at the initial distance and be repeated at increasing distance from the carrier until the upstream band edge, 5 MHz or 42 MHz, is reached. Measurement intervals should not include carrier related emissions.
+
+**Table B.4-8/J.112 – Spurious emissions in 5 to 42 MHz**
+
+| Possible symbol rate in this interval | Specification in the interval | Initial measurement interval and distance from carrier edge |
+|---------------------------------------|-------------------------------|-------------------------------------------------------------|
+| 160 ksym/s                            | -53 dBc                       | 220 to 380 kHz                                              |
+| 320 ksym/s                            | -50 dBc                       | 240 to 560 kHz                                              |
+| 640 ksym/s                            | -47 dBc                       | 280 to 920 kHz                                              |
+| 1280 ksym/s                           | -44 dBc                       | 360 to 1640 kHz                                             |
+| 2560 ksym/s                           | -41 dBc                       | 520 to 3080 kHz                                             |
+
+#### B.4.2.9.2 Spurious emissions during burst on/off transients
+
+Each transmitter MUST control spurious emissions, prior to and during ramp up and during and following ramp down, before and after a burst in the TDMA scheme.
+
+On/off spurious emissions, such as the change in voltage at the upstream transmitter output due to enabling or disabling transmission, MUST be no more than 100 mV, and such a step MUST be dissipated no faster than 2  $\mu\text{s}$  of constant slewing. This requirement applies when the CM is transmitting at +55 dBmV or more; at backed-off transmit levels, the maximum change in voltage MUST decrease by a factor of 2 for each 6-dB decrease of power level from +55 dBmV, down to a maximum change of 7 mV at 31 dBmV and below. This requirement does not apply to CM power-on and power-off transients.
+
+#### B.4.2.9.3 Symbol Error Rate (SER)
+
+Modulator performance MUST be within 0.5 dB of theoretical SER vs C/N (i.e.  $E_s/N_0$ ), for SER as low as  $10^{-6}$  uncoded, for QPSK and 16 QAM.
+
+The SER degradation is determined by the cluster variance caused by the transmit wave form at the output of an ideal square-root raised-cosine receive filter. It includes the effects of ISI, spurious, phase noise, and all other transmitter degradations.
+
+Cluster SNR should be measured on a modulation analyzer using a square-root raised cosine receive filter with  $\alpha=0.25$ . The measured SNR MUST be better than 30 dB.
+
+#### B.4.2.9.4 Filter distortion
+
+The following requirements assume that any pre-equalization is disabled.
+
+#### **B.4.2.9.4.1 Amplitude**
+
+The spectral mask MUST be the ideal square root raised cosine spectrum with  $\alpha = 0.25$ , within the ranges given below:
+
+$f_c - R_s/4$  Hz to  $f_c + R_s/4$  Hz:  $-0.3$  dB to  $+0.3$  dB
+
+$f_c - 3R_s/8$  Hz to  $f_c - R_s/4$  Hz, and  $f_c + R_s/4$  Hz to  $f_c + 3R_s/8$  Hz:  $-0.5$  dB to  $0.3$  dB
+
+$f_c - R_s/2$  Hz and  $f_c + R_s/2$  Hz:  $-3.5$  dB to  $-2.5$  dB
+
+$f_c - 5R_s/8$  Hz and  $f_c + 5R_s/8$  Hz: no greater than  $-30$  dB
+
+where  $f_c$  is the centre frequency,  $R_s$  is the symbol rate, and the spectral density is measured with a resolution bandwidth of 10 KHz or less.
+
+#### **B.4.2.9.4.2 Phase**
+
+$f_c - 5R_s/8$  Hz to  $f_c + 5R_s/8$  Hz: Group Delay Variation MUST NOT be greater than 100 ns.
+
+#### **B.4.2.9.5 Carrier phase noise**
+
+The upstream transmitter total integrated phase noise (including discrete spurious noise) MUST be less than or equal to  $-43$  dBc summed over the spectral regions spanning 1 kHz to 1.6 MHz above and below the carrier.
+
+#### **B.4.2.9.6 Channel frequency accuracy**
+
+The CM MUST implement the assigned channel frequency within  $\pm 50$  parts per million over a temperature range of 0 to 40 degrees C up to five years from date of manufacture.
+
+#### **B.4.2.9.7 Symbol rate accuracy**
+
+The upstream modulator MUST provide an absolute accuracy of symbol rates  $\pm 50$  parts per million over a temperature range of 0 to 40 degrees C up to five years from date of manufacture.
+
+#### **B.4.2.9.8 Symbol timing jitter**
+
+Peak-to-peak symbol jitter, referenced to the previous symbol zero-crossing, of the transmitted waveform, MUST be less than 0.02 of the nominal symbol duration over a 2-s period. In other words, the difference between the maximum and the minimum symbol duration during the 2-s period shall be less than 0.02 of the nominal symbol duration for each of the five upstream symbol rates.
+
+The peak-to-peak cumulative phase error, referenced to the first symbol time and with any fixed symbol frequency offset factored out, MUST be less than 0.04 of the nominal symbol duration over a 0.1-s period. In other words, the difference between the maximum and the minimum cumulative phase error during the 0.1-s period shall be less than 0.04 of the nominal symbol duration for each of the five upstream symbol rates. Factoring out a fixed symbol frequency offset is to be done by using the computed mean symbol duration during the 0.1 s.
+
+#### **B.4.2.10 Frame structure**
+
+Figure B.4-7 shows two examples of the frame structure: one where the packet length equals the number of information bytes in a code word, and another where the packet length is longer than the number of information bytes in one code word, but less than in two code words. Example 1 illustrates the fixed code-word length mode, and Example 2 illustrates the shortened last code-word mode. These modes are defined in B.4.2.10.1.
+
+**Example 1** – Packet length = number of information bytes in code word =  $k$
+
+![Diagram for Example 1 showing a single code word structure. It consists of five blocks: Preamble, Packet data, FEC parity, Guard time, and Empty up to next mini-Slot boundary. A double-headed arrow labeled 'One code word' spans over the Packet data and FEC parity blocks.](18b914bd6d55df64c6935e65803a3f79_img.jpg)
+
+|          |                   |            |            |                                     |
+|----------|-------------------|------------|------------|-------------------------------------|
+| Preamble | ← One code word → |            | Guard time | Empty up to next mini-Slot boundary |
+|          | Packet data       | FEC parity |            |                                     |
+
+Diagram for Example 1 showing a single code word structure. It consists of five blocks: Preamble, Packet data, FEC parity, Guard time, and Empty up to next mini-Slot boundary. A double-headed arrow labeled 'One code word' spans over the Packet data and FEC parity blocks.
+
+**Example 2** – Packet length =  $k$  + remaining information bytes in 2nd code word =  $k + k' \leq k + k'' \leq 2k$  bytes
+
+![Diagram for Example 2 showing a two code word structure. The top part shows Preamble, Two code words, and Guard time, with an arrow pointing to the 'Mini-slot boundary'. Below this, a dashed line leads to a detailed view of the two code words. The first code word contains 'First k bytes of packet' and 'FEC parity'. The second code word contains 'Last k' bytes of packet', 'k'' - k' bytes of zero-fill', and 'FEC parity'. A label 'T0904860-97/d057' is present at the bottom right.](9b39a1d27e49bccd8767e8d5fc0be7fd_img.jpg)
+
+|          |                |  |            |                      |
+|----------|----------------|--|------------|----------------------|
+| Preamble | Two code words |  | Guard time | ← Mini-slot boundary |
+|----------|----------------|--|------------|----------------------|
+
+  
+
+|                           |            |                           |                               |            |
+|---------------------------|------------|---------------------------|-------------------------------|------------|
+| First $k$ bytes of packet | FEC parity | Last $k'$ bytes of packet | $k'' - k'$ bytes of zero-fill | FEC parity |
+|---------------------------|------------|---------------------------|-------------------------------|------------|
+
+T0904860-97/d057
+
+Diagram for Example 2 showing a two code word structure. The top part shows Preamble, Two code words, and Guard time, with an arrow pointing to the 'Mini-slot boundary'. Below this, a dashed line leads to a detailed view of the two code words. The first code word contains 'First k bytes of packet' and 'FEC parity'. The second code word contains 'Last k' bytes of packet', 'k'' - k' bytes of zero-fill', and 'FEC parity'. A label 'T0904860-97/d057' is present at the bottom right.
+
+**Figure B.4-7/J.112** – Example frame structures with flexible burst length mode
+
+#### B.4.2.10.1 Code-word length
+
+The CM operates in fixed-length code-word mode or with shortened code-word capability enabled. The minimum number of information bytes in a code word, for fixed or shortened mode, is 16 bytes. Shortened code-word capability is available with  $k \geq 16$  bytes, where  $k$  is the number of information bytes in a code word. With  $k < 16$ , shortened code word capability is not available.
+
+The following descriptions apply to an allocated grant of mini-slots in both contention and non-contention regions. (Allocation of mini-slots is discussed in B.6.) The intent of the description is to define rules and conventions such that CMs request the proper number of mini-slots and the CMTS PHY knows what to expect regarding the FEC framing in both fixed code-word length and shortened last code-word modes.
+
+##### B.4.2.10.1.1 Fixed code-word length
+
+With the fixed-length code words, after all the data are encoded, zero-fill will occur in this code word if necessary to reach the assigned  $k$  data bytes per code word, and zero-fill MUST continue up to the point when no additional fixed-length code words can be inserted before the end of the last allocated min-slot in the grant, accounting for FEC parity and guard-time symbols.
+
+##### B.4.2.10.1.2 Shortened last code word
+
+As shown in Figure B.4-7, let  $k'$  = the number of information bytes that remain after partitioning the information bytes of the burst into full-length ( $k$  burst data bytes) code words. The value of  $k'$  is less than  $k$ . Given operation in a shortened last code-word mode, let  $k''$  = the number of burst data bytes plus zero-fill bytes in the shortened last code word. In shortened code-word mode, the CM will encode the data bytes of the burst (including MAC header) using the assigned code-word size ( $k$  information bytes per code word) until:
+
+- 1) all the data are encoded; or
+- 2) a remainder of data bytes is left over which is less than  $k$ .
+
+Shortened last code words shall not have less than 16 information bytes, and this is to be considered when CMs make requests of mini-slots. In shortened last code-word mode, the CM will zero-fill data if necessary until the end of the mini-slot allocation, which in most cases will be the next mini-slot boundary, accounting for FEC parity and guard-time symbols. In many cases, only  $k'' - k'$  zero-fill bytes are necessary to fill out a mini-slot allocation with  $16 \leq k'' \leq k$  and  $k' \leq k''$ . However, note the following.
+
+More generally, the CM is required to zero-fill data until the point when no additional fixed-length code words can be inserted before the end of the last allocated mini-slot in the grant (accounting for FEC parity and guard-time symbols), and then, if possible, a shortened last code word of zero-fill shall be inserted to fit into the mini-slot allocation.
+
+If, after zero-fill of additional code words with k information bytes, there are less than 16 bytes remaining in the allocated grant of mini-slots, accounting for parity and guard-time symbols, then the CM shall not create this last shortened code word.
+
+#### B.4.2.11 Signal processing requirements
+
+The signal processing order for each burst packet type MUST be compatible with the sequence shown in Figure B.4-8 and MUST follow the order of steps in Figure B.4-9.
+
+#### B.4.2.12 Upstream demodulator input power characteristics
+
+The maximum total input power to the upstream demodulator MUST NOT exceed 35 dBmV in the 5-42 MHz frequency range of operation.
+
+The intended received power in each carrier MUST be within the values shown in Table B.4-9.
+
+The demodulator MUST operate within its defined performance specifications with received bursts within  $\pm 6$  dB of the nominal commanded received power.
+
+**Table B.4-9/J.112 – Maximum range of commanded nominal receive power in each carrier**
+
+| Symbol rate (ksym/s) | Maximum range (dBmV) |
+|----------------------|----------------------|
+| 160                  | -16 to +14           |
+| 320                  | -13 to +17           |
+| 640                  | -10 to +20           |
+| 1280                 | -7 to +23            |
+| 2560                 | -4 to +26            |
+
+#### B.4.2.13 Upstream electrical output from the CM
+
+The CM MUST output an RF modulated signal with the characteristics delineated in Table B.4-10.
+
+**Table B.4-10/J.112 – Electrical output from CM**
+
+| Parameter                 | Value                                                |
+|---------------------------|------------------------------------------------------|
+| Frequency                 | 5 to 42 MHz edge-to-edge                             |
+| Level range (one channel) | +8 to +55 dBmV (16 QAM)<br>+8 to +58 dBmV (QPSK)     |
+| Modulation type           | QPSK and 16 QAM                                      |
+| Symbol rate (nominal)     | 160, 320, 640, 1280 and 2560 ksym/s                  |
+| Bandwidth                 | 200, 400, 800, 1600 and 3200 kHz                     |
+| Output impedance          | 75 ohms                                              |
+| Output return loss        | > 6 dB (5-42 MHz)                                    |
+| Connector                 | F connector per [IPS-SP-401] (common with the input) |
+
+### B.4.3 Downstream
+
+#### B.4.3.1 Downstream protocol
+
+The downstream PMD sublayer MUST conform to Annex B/J.83 for Low-Delay Video Applications [ITU-T J.83 B], with the exceptions called out in B.4.3.2.
+
+![Figure B.4-8/J.112 – Signal-processing sequence. This block diagram shows the signal processing flow for TDMA upstream transmission. The main sequence consists of seven blocks: 'Block the Data', 'FEC Encode', 'Scramble', a summation node (+), 'Symbol Map', 'Filter', and 'Modulate'. 'Burst Data In' enters the first block. A 'Preamble Prepend' block feeds into the summation node. A 'Modulator Control' block, receiving 'Parameter set from CMDS' and 'Transmit now edge', controls the 'Block the Data', 'FEC Encode', 'Scramble', 'Symbol Map', 'Filter', and 'Modulate' blocks. The 'Modulate' block outputs to 'Power Control' and 'Transmit on/off'. A small code 'T0906420-98/d058' is present near the bottom right of the diagram.](33cbd34b2ff74e39d12fae4db73f5b41_img.jpg)
+
+Figure B.4-8/J.112 – Signal-processing sequence. This block diagram shows the signal processing flow for TDMA upstream transmission. The main sequence consists of seven blocks: 'Block the Data', 'FEC Encode', 'Scramble', a summation node (+), 'Symbol Map', 'Filter', and 'Modulate'. 'Burst Data In' enters the first block. A 'Preamble Prepend' block feeds into the summation node. A 'Modulator Control' block, receiving 'Parameter set from CMDS' and 'Transmit now edge', controls the 'Block the Data', 'FEC Encode', 'Scramble', 'Symbol Map', 'Filter', and 'Modulate' blocks. The 'Modulate' block outputs to 'Power Control' and 'Transmit on/off'. A small code 'T0906420-98/d058' is present near the bottom right of the diagram.
+
+Figure B.4-8/J.112 – Signal-processing sequence
+
+![](80a44321a02e8a7d638ac9d53e88772c_img.jpg)
+
+|                         |                                                                                                                              |
+|-------------------------|------------------------------------------------------------------------------------------------------------------------------|
+|                         | Packet Stream Input                                                                                                          |
+|                         | ↓                                                                                                                            |
+| <b>Block the Data</b>   | Separate Packet into Information Blocks (= data bytes in one code word)                                                      |
+|                         | ↓                                                                                                                            |
+| <b>FEC Encode</b>       | FEC Encode (Reed-Solomon) each Information Block, using shortened code word for last block if needed. FEC can be turned off. |
+|                         | ↓                                                                                                                            |
+| <b>Scramble</b>         | Scramble (see B.4.2.4)                                                                                                       |
+|                         | ↓                                                                                                                            |
+| <b>Preamble Prepend</b> | Preamble prepend Symbols                                                                                                     |
+|                         | ↓                                                                                                                            |
+| <b>Symbol Map</b>       | Symbol Map the Data Stream into Modulator Symbols                                                                            |
+|                         | ↓                                                                                                                            |
+| <b>Filter</b>           | Filter Symbol Stream for Spectral Shaping                                                                                    |
+|                         | ↓                                                                                                                            |
+| <b>Modulate</b>         | Modulate at Precise Times (QPSK; 16 QAM)                                                                                     |
+|                         | ↓                                                                                                                            |
+|                         | Output RF Wave-form Bursts                                                                                                   |
+
+Figure B.4-9/J.112 – TDMA upstream transmission processing
+
+### B.4.3.2 Scalable interleaving to support low latency
+
+The downstream PMD sublayer MUST support a variable-depth interleaver with the characteristics defined in Table B.4-11. This table contains a subset of interleaver modes found in [ITU-T J.83 B].
+
+**Table B.4-11/J.112 – Interleaver characteristics**
+
+| <b>I<br/>(Number of taps)</b> | <b>J<br/>(Increment)</b> | <b>Burst protection<br/>64 QAM/256 QAM</b> | <b>Latency<br/>64 QAM/256 QAM</b> |
+|-------------------------------|--------------------------|--------------------------------------------|-----------------------------------|
+| 8                             | 16                       | 5.9 µs/4.1 µs                              | 0.22 ms/0.15 ms                   |
+| 16                            | 8                        | 12 µs/8.2 µs                               | 0.48 ms/0.33 ms                   |
+| 32                            | 4                        | 24 µs/16 µs                                | 0.98 ms/0.68 ms                   |
+| 64                            | 2                        | 47 µs/33 µs                                | 2.0 ms/1.4 ms                     |
+| 128                           | 1                        | 95 µs/66 µs                                | 4.0 ms/2.8 ms                     |
+
+The interleaver depth, which is coded in a 4-bit control word contained in the FEC frame synchronization trailer, always reflects the interleaving in the immediately-following frame. In addition, errors are allowed while the interleaver memory is flushed after a change in interleaving is indicated.
+
+Refer to [ITU-T J.83 B] for the control bit specifications required to specify which interleaving mode is used.
+
+#### **B.4.3.3 Downstream frequency plan**
+
+The downstream frequency plan should comply with Harmonic Related Carrier (HRC), Incremental Related Carrier (IRC) or Standard (STD) North American frequency plans per [IS-6]. However, operation below a centre frequency of 91 MHz is not required.
+
+#### **B.4.3.4 CMTS output electrical**
+
+The CMTS MUST output an RF modulated signal with the following characteristics defined in Table B.4-12.
+
+#### **B.4.3.5 Downstream electrical input to CM**
+
+The CM MUST accept an RF modulated signal with the following characteristics (see Table B.4-13.)
+
+#### **B.4.3.6 CM BER performance**
+
+The bit-error-rate performance of a CM MUST be as described in this subclause. The requirements apply to the I = 128, J = 1 mode of interleaving.
+
+##### **B.4.3.6.1 64 QAM**
+
+###### **B.4.3.6.1.1 64 QAM CM BER Performance**
+
+Implementation loss of the CM MUST be such that the CM achieves a post-FEC BER less than or equal to  $10^{-8}$  when operating at a carrier to noise ratio ( $E_s/N_0$ ) of 23.5 dB or greater.
+
+###### **B.4.3.6.1.2 64 QAM image rejection performance**
+
+Performance as described in B.4.3.6.1.1 MUST be met with analogue or digital signal at +10 dBc in any portion of the RF band other than the adjacent channels.
+
+###### **B.4.3.6.1.3 64 QAM Adjacent channel performance**
+
+Performance as described in B.4.3.6.1.1 MUST be met with digital signal at 0 dBc in the adjacent channels.
+
+Performance as described in B.4.3.6.1.1 MUST be met with analogue signal at +10 dBc in the adjacent channels.
+
+Performance as described in B.4.3.6.1.1, with an additional 0.2-dB allowance, MUST be met with digital signal at +10 dBc in the adjacent channels.
+
+##### **B.4.3.6.2 256 QAM**
+
+###### **B.4.3.6.2.1 256 QAM CM BER performance**
+
+Implementation loss of the CM MUST be such that the CM achieves a post-FEC BER less than or equal to  $10^{-8}$  when operating at a carrier to noise ratio ( $E_s/N_0$ ) of 30 dB or greater.
+
+**Table B.4-12/J.112 –CMTS output**
+
+| Parameter                                                       | Value                                                                                                                                                                                                                                  |
+|-----------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Centre Frequency ( $f_c$ )                                      | 91 to 857 MHz $\pm$ 30 kHz <sup>a)</sup>                                                                                                                                                                                               |
+| Level                                                           | Adjustable over the range 50 to 61 dBmV                                                                                                                                                                                                |
+| Modulation type                                                 | 64 QAM and 256 QAM                                                                                                                                                                                                                     |
+| Symbol rate (nominal)<br>64 QAM<br>256 QAM                      | 5.056941 Msym/s<br>5.360537 Msym/s                                                                                                                                                                                                     |
+| Nominal channel spacing                                         | 6 MHz                                                                                                                                                                                                                                  |
+| Frequency response<br>64 QAM<br>256 QAM                         | ~18% square root raised cosine shaping<br>~12% square root raised cosine shaping                                                                                                                                                       |
+| Total discrete spurious In-band ( $f_c \pm 3$ MHz)              | < -57 dBc                                                                                                                                                                                                                              |
+| In-band spurious and noise ( $f_c \pm 3$ MHz)                   | < -48 dBc; where channel spurious and noise includes all discrete spurious, noise, carrier leakage, clock lines, synthesizer products, and other undesired transmitter products. Noise within $\pm 50$ kHz of the carrier is excluded. |
+| Adjacent channel ( $f_c \pm 3.0$ MHz) to ( $f_c \pm 3.75$ MHz)  | < -58 dBc in 750 kHz.                                                                                                                                                                                                                  |
+| Adjacent channel ( $f_c \pm 3.75$ MHz) to ( $f_c \pm 9$ MHz)    | < -62 dBc in 5.25 MHz, excluding up to 3 spurs, each of which must be < -60 dBc when each is measured with 10 kHz bandwidth.                                                                                                           |
+| Next adjacent channel ( $f_c \pm 9$ MHz) to ( $f_c \pm 15$ MHz) | < -65 dBc in 6 MHz, excluding up to three discrete spurs. The total power in the spurs must be < -60 dBc when each is measured with 10 kHz bandwidth.                                                                                  |
+| Other channels (47 MHz to 1000 MHz)                             | < -12 dBmV in each 6 MHz channel, excluding up to three discrete spurs. The total power in the spurs must be < -60 dBc when each is measured with 10 kHz bandwidth.                                                                    |
+| Phase noise                                                     | 1 kHz-10 kHz: -33 dBc double sided noise power<br>10 kHz-50 kHz: -51 dBc double sided noise power<br>50 kHz-3 MHz: -51 dBc double sided noise power                                                                                    |
+| Output impedance                                                | 75 ohms                                                                                                                                                                                                                                |
+| Output return loss                                              | > 14 dB within an output channel up to 750 MHz; > 13 dB in an output channel above 750 MHz                                                                                                                                             |
+| Connector                                                       | F connector per [IPS-SP-401]                                                                                                                                                                                                           |
+
+<sup>a)</sup>  $\pm 30$  kHz includes an allowance of 25 kHz for the largest FCC frequency offset normally built into upconverters.
+
+**Table B.4-13/J.112 – Electrical input to CM**
+
+| Parameter                      | Value                                                                                                          |
+|--------------------------------|----------------------------------------------------------------------------------------------------------------|
+| Centre Frequency               | 91 to 857 MHz $\pm$ 30 kHz                                                                                     |
+| Level Range (one channel)      | –15 dBmV to +15 dBmV                                                                                           |
+| Modulation Type                | 64 QAM and 256 QAM                                                                                             |
+| Symbol Rate (nominal)          | 5.056941 Msym/s (64 QAM) and 5.360537 Msym/s (256 QAM)                                                         |
+| Bandwidth                      | 6 MHz (18% square root raised cosine shaping for 64 QAM and 12% square root raised cosine shaping for 256 QAM) |
+| Total Input Power (40-900 MHz) | < 30 dBmV                                                                                                      |
+| Input (load) Impedance         | 75 ohms                                                                                                        |
+| Input Return Loss              | > 6 dB (88 to 860 MHz)                                                                                         |
+| Connector                      | F connector per [IPS-SP-401] (common with the output)                                                          |
+
+**B.4.3.6.2.2 256 QAM image rejection performance**
+
+Performance as described in B.4.3.6.2.1 MUST be met with analogue or digital signal at +10 dBc in any portion of the RF band other than the adjacent channels.
+
+**B.4.3.6.2.3 256 QAM adjacent channel performance**
+
+Performance as described in B.4.3.6.2.1 MUST be met with analogue or digital signal at 0 dBc in the adjacent channels.
+
+Performance as described in B.4.3.6.2.1, with an additional 0.5-dB allowance, MUST be met with analogue signal at +10 dBc in the adjacent channels.
+
+Performance as described in B.4.3.6.2.1, with an additional 1.0-dB allowance, MUST be met with digital signal at +10 dBc in the adjacent channels.
+
+**B.4.3.7 CMTS timestamp jitter**
+
+The peak-to-peak jitter, measured at the output of the CMTS, MUST be less than 500 ns. This includes jitter from both the value in the timestamp message, and time of transmission of that message.
+
+The CM is expected to meet the burst timing accuracy requirements in B.4.2.6 when the time stamps contain this worst-case jitter.
+
+NOTE – Jitter is the error (i.e. measured) relative to the CMTS Master Clock. (The CMTS Master Clock is the 10.24 MHz clock used for generating the timestamps.)
+
+The CMTS 10.24 MHz Master Clock MUST have frequency stability of  $\leq \pm 5$  ppm, drift rate  $\leq 10^{-8}$  per second, and edge jitter of  $\leq 10$  ns peak-to-peak ( $\pm 5$  ns). (The drift rate and jitter requirements on the CMTS Master Clock implies that the duration of two adjacent segments of 10 240 000 cycles will be within 30 ns, due to 10 ns jitter on each segments' duration, and 10 ns due to frequency drift. Durations of other counter lengths also may be deduced: adjacent 1 024 000 segments,  $\leq 21$  ns; 1 024 000 length segments separated by one 10 240 000 cycles,  $\leq 30$  ns; adjacent 102 400 000 segments,  $\leq 120$  ns. The CMTS Master Clock MUST meet such test limits in 99% or more measurements.)
+
+**B.5 Downstream transmission convergence sublayer****B.5.1 Introduction**
+
+In order to improve demodulation robustness, facilitate common receiving hardware for both video and data, and provide an opportunity for the possible future multiplexing of video and data over the PMD sublayer bitstream defined in B.4, a sublayer is interposed between the downstream PMD sublayer and the Data-Over-Cable MAC sublayer.
+
+The downstream bitstream is defined as a continuous series of 188-byte MPEG [ITU-T H.222.0] packets. These packets consist of a 4-byte header followed by 184 bytes of payload. The header identifies the payload as belonging to the Data-Over-Cable MAC. Other values of the header may indicate other payloads. The mixture of MAC payloads and those of other services is optional and is controlled by the CM/MTS.
+
+Figure B.5-1 illustrates the interleaving of Data-Over-Cable (DOC) MAC bytes with other digital information (digital video in the example shown).
+
+|                |                       |
+|----------------|-----------------------|
+| Header = DOC   | DOC MAC payload       |
+| Header = video | Digital video payload |
+| Header = video | Digital video payload |
+| Header = DOC   | DOC MAC payload       |
+| Header = video | Digital video payload |
+| Header = DOC   | DOC MAC payload       |
+| Header = video | Digital video payload |
+| Header = video | Digital video payload |
+| Header = video | Digital video payload |
+
+**Figure B.5-1/J.112 – Example of interleaving MPEG packets in downstream**
+
+### B.5.2 MPEG Packet format
+
+The format of an MPEG Packet carrying MCNS data is shown in Figure B.5-2. The packet consists of a 4-byte MPEG Header, a pointer\_field (not present in all packets) and the MCNS Payload.
+
+|                          |                           |                                    |
+|--------------------------|---------------------------|------------------------------------|
+| MPEG Header<br>(4 bytes) | pointer_field<br>(1 byte) | MCNS Payload<br>(183 or 184 bytes) |
+|--------------------------|---------------------------|------------------------------------|
+
+**Figure B.5-2/J.112 – Format of an MPEG Packet**
+
+### B.5.3 MPEG Header for MCNS Data-Over-Cable
+
+The format of the MPEG Transport Stream Header is defined in 2.4/H.222.0 [ITU-T H.222.0]. The particular field values that distinguish Data-Over-Cable MAC streams are defined in Table B.5-1. Field names are from the ITU specification.
+
+The MPEG Header consists of 4 bytes that begin the 188-byte MPEG Packet. The format of the header for use on an MCNS Data-Over-Cable PID is restricted to that shown in Table B.5-1. The Header format conforms to the MPEG standard, but its use is restricted in this specification to NOT ALLOW inclusion of an adaptation\_field in the MPEG packets.
+
+### B.5.4 MPEG Payload for MCNS Data-Over-Cable
+
+The MPEG Payload portion of the MPEG Packet will carry the MCNS MAC frames. The first byte of the MPEG payload will be a 'pointer\_field' if the payload\_unit\_start\_indicator (PUSI) of the MPEG Header is set.
+
+**Table B.5-1/J.112 – MPEG Header format for MCNS Data-Over-Cable packets**
+
+| Field                                                                     | Length (bits) | Description                                                                                                                                                                     |
+|---------------------------------------------------------------------------|---------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| sync_byte                                                                 | 8             | 0x47; MPEG Packet Sync byte.                                                                                                                                                    |
+| transport_error_indicator                                                 | 1             | Indicates an error has occurred in the reception of the packet. This bit is reset to zero by the sender, and set to one whenever an error occurs in transmission of the packet. |
+| payload_unit_start_indicator                                              | 1             | A value of one indicates the presence of a pointer_field as the first byte of the payload (fifth byte of the packet)                                                            |
+| transport_priority                                                        | 1             | Reserved; set to zero.                                                                                                                                                          |
+| PID (see Note)                                                            | 13            | MCNS Data-Over-Cable well-known PID (0x1FFE)                                                                                                                                    |
+| transport_scrambling_control                                              | 2             | Reserved; set to '00'.                                                                                                                                                          |
+| adaptation_field_control                                                  | 2             | '01'; use of the adaptation_field is NOT ALLOWED on the MCNS PID.                                                                                                               |
+| continuity_counter                                                        | 4             | Cyclic counter within this PID                                                                                                                                                  |
+| NOTE – In the future, additional PIDs MAY be assigned to a CM. See B.9.3. |               |                                                                                                                                                                                 |
+
+### stuff\_byte
+
+This standard defines a stuff\_byte pattern having a value (0xFF) that is used within the MCNS Payload to fill any gaps between the MCNS MAC frames. This value is chosen as an unused value for the first byte of the MCNS MAC frame. The 'FC' byte of the MAC Header will be defined to never contain this value. (FC\_TYPE = '11' indicates a MAC-specific frame, and FC\_PARM = '11111' is not currently used and, according to this specification, is defined as an illegal value for FC\_PARM.)
+
+### pointer\_field
+
+The pointer\_field is present as the fifth byte of the MPEG packet (first byte following the MPEG Header) whenever the PUSI is set to one in the MPEG Header. The interpretation of the pointer\_field is as follows.
+
+The pointer\_field contains the number of bytes in this packet that immediately follow the pointer\_field that the CM decoder must skip past before looking for the beginning of an MCNS MAC Frame. A pointer field MUST be present if it is possible to begin a Data-Over-Cable MAC Frame in the packet, and MUST point to either:
+
+- 1) the beginning of the first MAC frame to start in the packet; or
+- 2) any stuff\_byte preceding the MAC frame.
+
+### B.5.5 Interaction with the MAC sublayer
+
+MAC frames may begin anywhere within an MPEG Packet, MAC frames may span MPEG packets, and several MAC frames may exist within an MPEG Packet.
+
+The following figures show the format of the MPEG packets that carry MCNS MAC frames. In all cases, the PUSI flag indicates the presence of the pointer\_field as the first byte of the MPEG Payload.
+
+Figure B.5-3 shows a MAC Frame that is positioned immediately after the pointer\_field byte. In this case, pointer\_field is zero, and the MCNS decoder will begin searching for a valid FC byte at the byte immediately following the pointer\_field.
+
+Figure B.5-4 shows the more general case where a MAC Frame is preceded by the tail of a previous MAC Frame and a sequence of stuffing bytes. In this case, the pointer\_field still identifies the first byte after the tail of Frame #1 (a stuff\_byte) as the position where the decoder should begin searching for a legal MAC sublayer FC value. This format allows the multiplexing operation in the CMTS to immediately insert a MAC Frame that is available for transmission if that frame arrives after the MPEG header and pointer\_field have been transmitted.
+
+|                           |                        |                                |                              |
+|---------------------------|------------------------|--------------------------------|------------------------------|
+| MPEG Header<br>(PUSI = 1) | pointer_field<br>(= 0) | MAC Frame<br>(up to 183 bytes) | stuff_byte(s)<br>(0 or more) |
+|---------------------------|------------------------|--------------------------------|------------------------------|
+
+**Figure B.5-3/J.112 – Packet format where a MAC Frame immediately follows the pointer\_field**
+
+In order to facilitate multiplexing of the MPEG packet stream carrying MCNS data with other MPEG-encoded data, the CMTS SHOULD NOT transmit MPEG packets with the MCNS PID which contain only stuff\_bytes in the payload area. MPEG null packets SHOULD be transmitted instead. Note that there are timing relationships implicit in the MCNS MAC sublayer which must also be preserved by any MPEG multiplexing operation.
+
+|                           |                        |                                   |                              |                          |
+|---------------------------|------------------------|-----------------------------------|------------------------------|--------------------------|
+| MPEG Header<br>(PUSI = 1) | pointer_field<br>(= M) | Tail of MAC Frame #1<br>(M bytes) | stuff_byte(s)<br>(0 or more) | Start of MAC<br>Frame #2 |
+|---------------------------|------------------------|-----------------------------------|------------------------------|--------------------------|
+
+**Figure B.5-4/J.112 – Packet format with MAC Frame preceded by stuffing bytes**
+
+Figure B.5-5 shows that multiple MAC frames may be contained within the MPEG Packet. The MAC frames may be concatenated one after the other or be separated by an optional sequence of stuffing bytes.
+
+|                           |                        |                 |                 |                              |                 |
+|---------------------------|------------------------|-----------------|-----------------|------------------------------|-----------------|
+| MPEG Header<br>(PUSI = 1) | pointer_field<br>(= 0) | MAC Frame<br>#1 | MAC Frame<br>#2 | stuff_byte(s)<br>(0 or more) | MAC Frame<br>#3 |
+|---------------------------|------------------------|-----------------|-----------------|------------------------------|-----------------|
+
+**Figure B.5-5/J.112 – Packet format showing multiple MAC frames in a single packet**
+
+Figure B.5-6 shows the case where a MAC Frame spans multiple MPEG packets. In this case, the pointer\_field of the succeeding frame points to the byte following the last byte of the tail of the first frame.
+
+The Transmission Convergence sublayer must operate closely with the MAC sublayer in providing an accurate timestamp to be inserted into the Time Synchronization message (refer to B.6.3.2.1 and B.6.5).
+
+|                           |                                              |                                   |                                            |                                    |
+|---------------------------|----------------------------------------------|-----------------------------------|--------------------------------------------|------------------------------------|
+| MPEG Header<br>(PUSI = 1) | pointer_field<br>(= 0)                       | stuff_byte(s)<br>(0 or more)      | Start of MAC Frame #1<br>(up to 183 bytes) |                                    |
+| MPEG Header<br>(PUSI = 0) | Continuation of MAC Frame # 1<br>(184 bytes) |                                   |                                            |                                    |
+| MPEG Header<br>(PUSI = 1) | pointer_field<br>(= M)                       | Tail of MAC Frame #1<br>(M bytes) | stuff_byte(s)<br>(0 or more)               | Start of MAC Frame #2<br>(M bytes) |
+
+**Figure B.5-6/J.112 – Packet format where a MAC Frame spans multiple packets**
+
+#### **B.5.6 Interaction with the Physical layer**
+
+The MPEG-2 packet stream MUST be encoded according to [ITU-T J.83 B], including MPEG-2 transport framing using a parity checksum as described in [ITU-T J.83 B].
+
+### **B.5.7 MPEG Header synchronization and recovery**
+
+The MPEG-2 packet stream SHOULD be declared "in frame" (i.e. correct packet alignment has been achieved) when five consecutive correct parity checksums, each 188 bytes from the previous one, have been received.
+
+The MPEG-2 packet stream SHOULD be declared "out of frame", and a search for correct packet alignment started, when nine consecutive incorrect parity checksums are received.
+
+The format of MAC frames is described in detail in B.6.
+
+## **B.6 Media access control specification**
+
+### **B.6.1 Introduction**
+
+#### **B.6.1.1 Overview**
+
+This subclause describes version 1.0 of the MCNS MAC protocol. Some of the MAC protocol highlights include:
+
+- Bandwidth allocation controlled by CMTS.
+- A stream of mini-slots in the upstream.
+- Dynamic mix of contention- and reservation-based upstream transmit opportunities.
+- Bandwidth efficiency through support of variable-length packets.
+- Extensions provided for future support of ATM or other Data PDU.
+- Class of service support.
+- Extensions provided for security at the Data Link layer.
+- Support for a wide range of data rates.
+
+#### **B.6.1.2 Definitions**
+
+##### **B.6.1.2.1 MAC-sublayer domain**
+
+A MAC-sublayer domain is a collection of upstream and downstream channels for which a single MAC Allocation and Management protocol operates. Its attachments include one CMTS and some number of CMs. The CMTS MUST service all of the upstream and downstream channels; each CM MAY access one or more upstream and downstream channels.
+
+##### **B.6.1.2.2 MAC service access point**
+
+A MAC Service Access Point (MSAP) is an attachment to a MAC-sublayer domain.
+
+##### **B.6.1.2.3 Service ID**
+
+The concept of Service IDs is central to the operation of the MAC protocol. Service IDs provide both device identification and class-of-service management. In particular, they are integral to upstream bandwidth allocation.
+
+A Service ID defines a particular mapping between a CM and the CMTS. This mapping is the basis on which bandwidth is allocated to the CM by the CMTS and by which class of service is implemented. Within a MAC-sublayer domain, all Service IDs MUST be unique.
+
+The CMTS MAY assign one or more Service IDs (SIDs) to each CM, corresponding to the classes of service required by the CM. This mapping MUST be negotiated between the CMTS and the CM during CM registration.
+
+In a basic CM implementation, a single Service ID can be used, for example to offer best-effort IP service. However, the Service ID concept allows for more complex CMs to be developed with support for multiple service classes while supporting interoperability with more basic modems. In particular, the Service ID concept is expected to support the concept of "data flows" on which protocols such as RSVP and RTP are based.
+
+The Service ID is unique within a single MAC-sublayer domain. The length of the Service ID is 14 bits (although the Service ID is sometimes carried in the low-order bits of a 16-bit field).
+
+#### B.6.1.2.4 Upstream intervals, Mini-slots and 6.25-μs increments
+
+The upstream transmission time-line is divided into intervals by the upstream bandwidth allocation mechanism. Each interval is an integral number of mini-slots. A "mini-slot" is the unit of granularity for upstream transmission opportunities. There is no implication that any PDU can actually be transmitted in a single mini-slot. Each interval is labeled with a usage code which defines both the type of traffic that can be transmitted during that interval and the physical-layer modulation encoding. A mini-slot is a power-of-two multiple of 6.25-μs increments, i.e. 1, 2, 4, 8, 16, 32, 64, or 128 times 6.25 μs. The relationship between mini-slots, bytes, and time ticks is described further in B.6.5.4. The usage code values are defined in Table B.6-16 and allowed use is defined in B.6.3. The binding of these values to physical-layer parameters is defined in Table B.6-14.
+
+#### B.6.1.2.5 Frame
+
+A frame is a unit of data exchanged between two (or more) entities at the Data Link Layer. A MAC Frame consists of a MAC Header (beginning with a Frame Control byte; see Figure B.6-3), and may incorporate ATM cells or a variable-length data PDU. The variable-length PDU includes a pair of 48-bit addresses, data, and a CRC sum. In special cases, the MAC Header may encapsulate multiple MAC frames (see B.6.2.5.4).
+
+#### B.6.1.3 Future use
+
+A number of fields are defined as being "for future use" in the various MAC frames described in this annex. These fields MUST NOT be interpreted or used in any manner by this version (1.0) of the MAC protocol.
+
+### B.6.2 MAC Frame formats
+
+#### B.6.2.1 Generic MAC Frame format
+
+A MAC Frame is the basic unit of transfer between MAC sublayers at the CMTS and the cable modem. The same basic structure is used in both the upstream and downstream directions. MAC frames are variable in length. The term "Frame" is used in this context to indicate a unit of information that is passed between MAC sublayer peers. This is not to be confused with the term "framing" that indicates some fixed timing relationship.
+
+There are three distinct regions to consider, as shown in Figure B.6-1. Preceding the MAC Frame is either PMD sublayer overhead (upstream) or an MPEG transmission convergence header (downstream). The first part of the MAC Frame is the MAC Header. The MAC Header uniquely identifies the contents of the MAC Frame. Following the header is the optional Data PDU region. The format of the Data PDU and whether it is even present is described in the MAC Header.
+
+![Diagram of Generic MAC Frame format showing PMD overhead (upstream), MPEG PSI Header (downstream), MAC Header, and Data PDU (optional) within a MAC Frame.](4c3cf5d00a9dfdf1705e49f7f3a3d93a_img.jpg)
+
+The diagram illustrates the structure of a MAC Frame. It shows three main components: PMD overhead (upstream), MPEG PSI Header (downstream), and the MAC Frame itself. The MAC Frame is composed of a MAC Header and an optional Data PDU. The MAC Header is shown as a box labeled "MAC Header (see Figure B.6-3)". The Data PDU is shown as a box labeled "Data PDU (optional) (see Figure B.6-4)". A bracket below these two boxes labels them as the "MAC Frame". The PMD overhead (upstream) is shown as a box above the MAC Frame. The MPEG PSI Header (downstream) is shown as a box below the MAC Frame. The text "T0906430-98/d059" is located in the bottom right corner of the diagram area.
+
+Diagram of Generic MAC Frame format showing PMD overhead (upstream), MPEG PSI Header (downstream), MAC Header, and Data PDU (optional) within a MAC Frame.
+
+Figure B.6-1/J.112 – Generic MAC Frame format
+
+### B.6.2.1.1 PMD overhead
+
+In the upstream direction, the PHY layer indicates the start of the MAC Frame to the MAC sublayer. From the MAC sublayer's perspective, it only needs to know the total amount of overhead so it can account for it in the Bandwidth Allocation process. More information on this may be found in the PMD sublayer clause (see B.6.4).
+
+The FEC overhead is spread throughout the MAC frame and is assumed to be transparent to the MAC data stream. The MAC sublayer does need to be able to account for the overhead when doing Bandwidth Allocation. More information on this may be found in the Upstream Bandwidth Allocation clause (see B.6.4).
+
+### B.6.2.1.2 MAC Frame transport
+
+The transport of MAC frames by the PMD sublayer for upstream channels is shown in Figure B.6-2.
+
+![Diagram of upstream MAC/PMD convergence showing MAC frames being segmented into bursts with PMD overhead and FEC.](55d0ecdde4d2ccdeedbd144ac0fecd2d_img.jpg)
+
+The diagram illustrates the upstream MAC/PMD convergence process. It is divided into three horizontal layers by dashed lines: 'Upper layer' at the top, 'MAC sublayer' in the middle, and 'PMD sublayer' at the bottom. In the MAC sublayer, three 'MAC Frame' blocks are shown, with ellipses indicating more frames. Vertical dashed lines extend from the start of each MAC frame down to the PMD sublayer. In the PMD sublayer, each MAC frame is shown as a sequence of segments: 'PMD overhead', 'Data', and 'FEC'. Arrows labeled 'Start of burst at mini-slot boundary' point to the beginning of each sequence. Additional ellipses and labels like 'PMD overhead' are present at the ends of the sequences. A small text label 'T0904890-97/d060' is in the bottom right corner.
+
+Diagram of upstream MAC/PMD convergence showing MAC frames being segmented into bursts with PMD overhead and FEC.
+
+Figure B.6-2/J.112 – Upstream MAC/PMD convergence
+
+The layering of MAC frames over MPEG in the downstream channel is described in B.5.
+
+### B.6.2.1.3 Ordering of bits and octets
+
+Within an octet, the least-significant bit is the first transmitted on the wire. This follows the convention used by Ethernet and [ISO/IEC 8802-3]. This is often called bit-little-indian order<sup>3</sup>.
+
+<sup>3</sup> This applies to the upstream channel only. For the downstream channel, the MPEG transmission convergence sublayer presents an octet-wide interface to the MAC, so the MAC sublayer does not define the bit order.
+
+Within the MAC layer, when numeric quantities are represented by more than one octet (i.e. 16-bit and 32-bit values), the octet containing the most-significant bits is the first transmitted on the wire. This subclause follows the textual convention that when bit-fields are presented in tables, the most-significant bits are topmost in the table. For example, in Table B.6-2, FC\_TYPE occupies the two most-significant bits and EHDR\_ON occupies the least-significant bit. This is sometimes called byte-big-indian order.
+
+#### B.6.2.1.3.1 Representing negative numbers
+
+Signed integer values will be transmitted and received in two's complement format.
+
+#### B.6.2.1.4 MAC Header format
+
+The MAC Header format MUST be as shown in Figure B.6-3.
+
+![Diagram of MAC Header format showing fields FC (1 byte), MAC_PARM (1 byte), LEN (SID) (2 bytes), EHDR (0-240 bytes), and HCS (2 bytes). The FC field is expanded to show its internal bit fields: FC_TYPE (2 bits), FC_PARM (5 bits), and EHDR_ON (1 bit).](886af5e2ffd5d8f11079c547675cf882_img.jpg)
+
+The diagram illustrates the MAC Header structure. The main header consists of five fields: FC (1 byte), MAC\_PARM (1 byte), LEN (SID) (2 bytes), EHDR (0-240 bytes), and HCS (2 bytes). The FC field is expanded to show its internal bit fields: FC\_TYPE (2 bits), FC\_PARM (5 bits), and EHDR\_ON (1 bit). The text 'T0906440-98/d061' is located to the right of the diagram.
+
+Diagram of MAC Header format showing fields FC (1 byte), MAC\_PARM (1 byte), LEN (SID) (2 bytes), EHDR (0-240 bytes), and HCS (2 bytes). The FC field is expanded to show its internal bit fields: FC\_TYPE (2 bits), FC\_PARM (5 bits), and EHDR\_ON (1 bit).
+
+Figure B.6-3/J.112 – MAC Header format
+
+All MAC headers MUST have the general format as shown in Table B.6-1. The Frame Control (FC) field is the first byte and uniquely identifies the rest of the contents within the MAC Header. The FC field is followed by 3 bytes of MAC control; an OPTIONAL Extended Header (EHDR) field; plus a Header Check Sequence (HCS) to ensure the integrity of the MAC Header.
+
+Table B.6-1/J.112 – Generic MAC Header format
+
+| MAC Header field | Usage                                                                                                                                                                                                                                                                       | Size           |
+|------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------|
+| FC               | Frame Control: identifies type of MAC Header                                                                                                                                                                                                                                | 8 bits         |
+| MAC_PARM         | Parameter field whose use is dependent on FC:<br>if EHDR_ON = 1; used for EHDR field length (ELEN)<br>else if for concatenated frames (see Table B.6-14) used for MAC frame count<br>else (for Requests only) indicates the number of mini-slots and/or ATM cells requested | 8 bits         |
+| LEN (SID)        | The length of the MAC frame: the length is defined to be the sum of the number of bytes in the extended header (if present) and the number of bytes following the HCS field. (For a REQ Header, this field is the Service ID instead)                                       | 16 bits        |
+| EHDR             | Extended MAC Header (where present; variable size).                                                                                                                                                                                                                         | 0-240 bytes    |
+| HCS              | MAC Header check sequence                                                                                                                                                                                                                                                   | 2 bytes        |
+|                  | Length of a MAC Header                                                                                                                                                                                                                                                      | 6 bytes + EHDR |
+
+The HCS field is a 16-bit CRC that ensures the integrity of the MAC Header, even in a collision environment. The HCS field coverage MUST include the entire MAC Header, starting with the FC field and including any EHDR field that may be present. The HCS is calculated using CRC-CCITT ( $x^{16} + x^{12} + x^5 + 1$ ) as defined in [ITU-T X.25].
+
+The FC field is broken down into the FC\_TYPE sub-field, FC\_PARM sub-field and an EHDR\_ON indication flag. The format of the FC field MUST be as shown in Table B.6-2.
+
+**Table B.6-2/J.112 – FC field format**
+
+| FC field | Usage                                                                                                                                          | Size   |
+|----------|------------------------------------------------------------------------------------------------------------------------------------------------|--------|
+| FC_TYPE  | MAC Frame Control type field:<br>00: Packet PDU MAC Header<br>01: ATM PDU MAC Header<br>10: Reserved PDU MAC Header<br>11: MAC-specific Header | 2 bits |
+| FC_PARM  | Parameter bits, use dependent on FC_TYPE.                                                                                                      | 5 bits |
+| EHDR_ON  | When = 1, indicates that EHDR field is present.<br>[Length of EHDR (ELEN) determined by MAC_PARM field]                                        | 1 bit  |
+
+The FC\_TYPE sub-field is the two MSBs of the FC field. These bits MUST always be interpreted in the same manner to indicate one of four possible MAC frame formats. These types include: MAC Header with Packet PDU; MAC Header with ATM cells; MAC Header reserved for future PDU types; or a MAC Header used for specific MAC control purposes. These types are spelled out in more detail in the remainder of this subclause.
+
+The five bits following the FC\_TYPE sub-field form the FC\_PARM sub-field. The use of these bits is dependent on the type of MAC Header. The LSB of the FC field is the EHDR\_ON indicator. If this bit is set, then an Extended Header (EHDR) is present. The EHDR provides a mechanism to allow the MAC Header to be extensible in an interoperable manner.
+
+The Transmission Convergence Sublayer stuff-byte pattern is defined to be a value of 0xFF. This precludes the use of FC byte values which have FC\_TYPE = '11' and FC\_PARM = '11111'.
+
+The MAC\_PARM field of the MAC Header serves several purposes depending on the FC field. If the EHDR\_ON indicator is set, then the MAC\_PARM field MUST be used as the Extended Header length (ELEN). The EHDR field MAY vary from 0 to 240 bytes. If this is a concatenation MAC Header, then the MAC\_PARM field represents the number of MAC frames (CNT) in the concatenation (see B.6.2.5.4). If this is a Request MAC Header (REQ) (see B.6.2.5.3), then the MAC\_PARM field represents the amount of bandwidth being requested. In all other cases, the MAC\_PARM field is reserved for future use.
+
+The third field has two possible uses. In most cases, it indicates the length (LEN) of this MAC frame. In one special case, the Request MAC Header, it is used to indicate the cable modem's Service ID since no PDU follows the MAC Header.
+
+The Extended Header (EHDR) field provides extensions to the MAC frame format. It is used to implement data link security and can be extended to add support for additional functions in future releases. Initial implementations SHOULD pass this field to the processor. This will allow future software upgrades to take advantage of this capability. (Refer to B.6.2.6, "Extended MAC Headers", for details.)
+
+#### **B.6.2.1.5 Data PDU**
+
+The MAC Header MAY be followed by a Data PDU. The type and format of the Data PDU is defined in the Frame Control field of the MAC Header. The FC field explicitly defines a Packet Data PDU, an ATM Data PDU, a MAC Header only frame (no PDU) and a reserved code point (used as an escape mechanism for future extensions). All CMs MUST use the length in the MAC Header to skip over any reserved data.
+
+### B.6.2.2 Packet-Based MAC frames
+
+#### B.6.2.2.1 Variable-length packets
+
+The MAC sublayer MUST support a variable-length Ethernet and [ISO/IEC 8802-3] type Packet Data PDU. The Packet PDU MUST be passed across the network in its entirety, including its original CRC. A unique Packet MAC Header is appended to the beginning. The frame format without an Extended header MUST be as shown in Figure B.6-4 and Table B.6-3.
+
+![Diagram of Ethernet and ISO/IEC 8802-3 Packet PDU format. The top row shows the main fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Packet PDU (18-1518 bytes). The FC field is expanded into FC_TYPE (00), FC_PARM (00000), and EHDR_ON (0). The Packet PDU is expanded into DA (6 bytes), SA (6 bytes), Type/Len (2 bytes), User Data (0-1500), and CRC (4 bytes).](8faeb7db381e28ab1ba06e9f48c19c6e_img.jpg)
+
+The diagram illustrates the structure of a Packet MAC frame. The top row shows the main fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Packet PDU (18-1518 bytes). The FC field is expanded into three sub-fields: FC\_TYPE (00), FC\_PARM (00000), and EHDR\_ON (0). The Packet PDU is expanded into five sub-fields: DA (6 bytes), SA (6 bytes), Type/Len (2 bytes), User Data (0-1500), and CRC (4 bytes). The diagram is labeled T0904910-97/d062.
+
+Diagram of Ethernet and ISO/IEC 8802-3 Packet PDU format. The top row shows the main fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Packet PDU (18-1518 bytes). The FC field is expanded into FC\_TYPE (00), FC\_PARM (00000), and EHDR\_ON (0). The Packet PDU is expanded into DA (6 bytes), SA (6 bytes), Type/Len (2 bytes), User Data (0-1500), and CRC (4 bytes).
+
+NOTE – Frame size is limited to 1518 bytes in the absence of VLAN tagging. Cooperating devices which implement IEEE 802.1Q VLAN tagging MAY use a frame size up to 1522 bytes.
+
+**Figure B.6-4/J.112 – Ethernet and ISO/IEC 8802-3 Packet PDU format**
+
+**Table B.6-3/J.112 – Packet PDU format**
+
+| Field       | Usage                                                                                                                                                                                                                                                                           | Size        |
+|-------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------|
+| FC          | FC_TYPE = 00; Packet MAC Header.<br>FC_PARM[4:0] = 00000; other values reserved for future use and ignored.<br>EHDR_ON = 0; no EHDR present this example.                                                                                                                       | 8 bits      |
+| MAC_PARM    | Reserved, MUST be set to zero if there is no EHDR; otherwise set to length of EHDR.                                                                                                                                                                                             | 8 bits      |
+| LEN         | LEN = n; length of Packet PDU in bytes.                                                                                                                                                                                                                                         | 16 bits     |
+| EHDR        | Extended MAC Header not present in this example                                                                                                                                                                                                                                 | 0 bytes     |
+| HCS         | MAC Header check sequence                                                                                                                                                                                                                                                       | 2 bytes     |
+| Packet data | Packet PDU:<br>DA – 48 bit Destination address<br>SA – 48 bit Source address<br>Type/Len – 16-bit Ethernet type or [ISO/IEC 8802-3] length field<br>User Data (variable length, 0-1500 bytes)<br>CRC – 32-bit CRC over packet PDU (as defined in Ethernet and [ISO/IEC 8802-3]) | n bytes     |
+|             | Length of Packet MAC frame                                                                                                                                                                                                                                                      | 6 + n bytes |
+
+### B.6.2.3 ATM cell MAC frames
+
+ATM transport is not defined in this specification.
+
+In order to allow current frame-based CMs to operate in a possible future downstream channel in which ATM cells and frames are mixed, a code point for ATM has been defined. This will allow current modems to ignore ATM cells while receiving frames. The frame format MUST be as shown in Figure B.6-5 and Table B.6-4.
+
+![Diagram of ATM cell MAC Frame format. The main frame consists of five fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and ATM cells (n x 53 bytes). A dashed line from the FC field points to a detailed view showing its internal structure: FC_TYPE = 01, FC_PARM = 00000, and EHDR_ON = 0. The diagram is labeled T0904920-97/d063.](e47d450f315d0b633906c03cc91f90ef_img.jpg)
+
+Diagram of ATM cell MAC Frame format. The main frame consists of five fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and ATM cells (n x 53 bytes). A dashed line from the FC field points to a detailed view showing its internal structure: FC\_TYPE = 01, FC\_PARM = 00000, and EHDR\_ON = 0. The diagram is labeled T0904920-97/d063.
+
+**Figure B.6-5/J.112 – ATM cell MAC Frame format**
+
+**Table B.6-4/J.112 – ATM cell MAC Frame format**
+
+| Field    | Usage                                                                                                                                                                 | Size             |
+|----------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------|
+| FC       | FC_TYPE = 01; ATM cell format MAC Header.<br>FC_PARM[4:0] = 00000; other values reserved for future use and ignored.<br>EHDR_ON = 0; no EHDR present in this example. | 8 bits           |
+| MAC_PARM | Reserved, MUST be set to zero if there is no EHDR; otherwise set to length of EHDR.                                                                                   | 8 bits           |
+| LEN      | LEN = n × 53; length of ATM cell PDU, in bytes                                                                                                                        | 16 bits          |
+| EHDR     | Extended MAC Header not present in this example                                                                                                                       | 0 bytes          |
+| HCS      | MAC Header check sequence                                                                                                                                             | 2 bytes          |
+| ATM data | ATM cell PDU                                                                                                                                                          | n × 53 bytes     |
+|          | Length of ATM cells based MAC Frame                                                                                                                                   | 6 + n × 53 bytes |
+
+#### B.6.2.4 Reserved PDU MAC frames
+
+The MAC sublayer provides a reserved FC code point to allow for support of future (to be defined) PDU formats. The FC field of the MAC Header indicates that a Reserved PDU is present. This PDU MUST be silently discarded by MAC implementations of this version (1.0) of the specification. Compliant version 1.0 implementations MUST use the length field to skip over the Reserved PDU.
+
+The format of the Reserved PDU without an extended header MUST be as shown in Figure B.6-6 and Table B.6-5.
+
+![Diagram of Reserved PDU format. The main frame consists of five fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Reserved PDU (n bytes). A dashed line from the FC field points to a detailed view showing its internal structure: FC_TYPE = 10, FC_PARM = RRRRR, and EHDR_ON = 0. The diagram is labeled T0904930-97/d064.](c81ba32b61950526476a859c10956433_img.jpg)
+
+Diagram of Reserved PDU format. The main frame consists of five fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Reserved PDU (n bytes). A dashed line from the FC field points to a detailed view showing its internal structure: FC\_TYPE = 10, FC\_PARM = RRRRR, and EHDR\_ON = 0. The diagram is labeled T0904930-97/d064.
+
+**Figure B.6-6/J.112 – Reserved PDU format**
+
+**Table B.6-5/J.112 – Reserved PDU format**
+
+| Field     | Usage                                                                                                                             | Size        |
+|-----------|-----------------------------------------------------------------------------------------------------------------------------------|-------------|
+| FC        | FC_TYPE = 10; Reserved PDU MAC Header.<br>FC_PARM[4:0]; reserved for future use.<br>EHDR_ON = 0; no EHDR present in this example. | 8 bits      |
+| MAC_PARM  | Reserved for future use                                                                                                           | 8 bits      |
+| LEN       | LEN = n; length of Reserved PDU in bytes.                                                                                         | 16 bits     |
+| EHDR      | EHDR = 0; extended MAC Header not present in this example.                                                                        | 0 bytes     |
+| HCS       | MAC Header check sequence                                                                                                         | 2 bytes     |
+| User data | Reserved Data PDU                                                                                                                 | n bytes     |
+|           | Length of a Reserved PDU MAC Frame                                                                                                | 6 + n bytes |
+
+**B.6.2.5 MAC-specific headers**
+
+There are several MAC headers which are used for very specific functions. These functions include support for downstream timing and upstream ranging/power adjust, requesting bandwidth and concatenating multiple MAC frames.
+
+**B.6.2.5.1 Timing Header**
+
+A specific MAC Header is identified to help support the timing and adjustments required. In the downstream, this MAC Header MUST be used to transport the Global Timing Reference to which all cable modems synchronize. In the upstream, this MAC Header MUST be used as part of the Ranging message needed for a cable modem’s timing and power adjustments. The Timing MAC Header is followed by a Packet Data PDU. The format MUST be as shown in Figure B.6-7 and Table B.6-6.
+
+![Diagram of the Timing MAC Header structure. It shows a sequence of fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Packet PDU (various lengths). A dashed line with arrows points from the FC field to a detailed view of its 8-bit structure: FC_TYPE = 11, FC_PARM = 00000, and EHDR_ON = 0. The diagram is labeled T0904940-97/d065.](eea0bd1826a6e1bdcadff03936a7b20a_img.jpg)
+
+Diagram of the Timing MAC Header structure. It shows a sequence of fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Packet PDU (various lengths). A dashed line with arrows points from the FC field to a detailed view of its 8-bit structure: FC\_TYPE = 11, FC\_PARM = 00000, and EHDR\_ON = 0. The diagram is labeled T0904940-97/d065.
+
+**Figure B.6-7/J.112 – Timing MAC Header**
+
+**B.6.2.5.2 MAC management Header**
+
+A specific MAC Header is identified to help support the MAC management messages required. This MAC Header MUST be used to transport all MAC management messages (refer to B.6.3). The format MUST be as shown Figure B.6-8 and Table B.6-7.
+
+**Table B.6-6/J.112 – Timing MAC Header format**
+
+| Field       | Usage                                                                                                                                           | Size        |
+|-------------|-------------------------------------------------------------------------------------------------------------------------------------------------|-------------|
+| FC          | FC_TYPE = 11; MAC-specific Header.<br>FC_PARM[4:0] = 00000; timing MAC Header.<br>EHDR_ON = 0; extended header prohibited for SYNC and RNG-REQ. | 8 bits      |
+| MAC_PARM    | Reserved for future use                                                                                                                         | 8 bits      |
+| LEN         | LEN = n; length of Packet PDU in bytes.                                                                                                         | 16 bits     |
+| EHDR        | Extended MAC Header not present                                                                                                                 | 0 bytes     |
+| HCS         | MAC Header check sequence                                                                                                                       | 2 bytes     |
+| Packet data | MAC Management message:<br>SYNC message (downstream only)<br>RNG-REQ (upstream only)                                                            | n bytes     |
+|             | Length of Timing Message MAC Frame                                                                                                              | 6 + n bytes |
+
+![Diagram of Management MAC Header structure. The top row shows fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and MAC Management message. A dashed line from the FC field points to a detailed view below, which shows FC_TYPE = 11, FC_PARM = 00001, and EHDR_ON. A label T0904950-97/d066 is present to the right.](4c63a0e17b54c7e61d512c276932114c_img.jpg)
+
+Diagram of Management MAC Header structure. The top row shows fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and MAC Management message. A dashed line from the FC field points to a detailed view below, which shows FC\_TYPE = 11, FC\_PARM = 00001, and EHDR\_ON. A label T0904950-97/d066 is present to the right.
+
+**Figure B.6-8/J.112 – Management MAC Header**
+
+**Table B.6-7/J.112 – Management MAC Header format**
+
+| Field       | Usage                                                                 | Size               |
+|-------------|-----------------------------------------------------------------------|--------------------|
+| FC          | FC_TYPE = 11; MAC-specific Header.<br>FC_PARM[4:0] = 00001<br>EHDR_ON | 8 bits             |
+| MAC_PARM    | Reserved for future use                                               | 8 bits             |
+| LEN         | LEN = n; length of Packet PDU in bytes.                               | 16 bits            |
+| EHDR        | Extended MAC Header not present in this example                       | 0 bytes            |
+| HCS         | MAC Header check sequence                                             | 2 bytes            |
+| Packet data | MAC Management message                                                | n bytes            |
+|             | Length of Management MAC Frame                                        | 6 + n bytes + EHDR |
+
+**B.6.2.5.3 Request MAC Header**
+
+The Request MAC Header is the basic mechanism that a cable modem uses to request bandwidth. As such, it is only applicable in the upstream. There MUST be no Data PDUs following the Request MAC Header. The general format of the Request MUST be as shown in Figure B.6-9 and Table B.6-8.
+
+Because the Request MAC Header does not have a Data PDU following it, the LEN field is not needed. The LEN field MUST be replaced with an SID. The SID MUST uniquely identify a particular service queue within a given station.
+
+The bandwidth request, REQ, MUST be specified in either mini-slots or in ATM cells. The REQ field MUST indicate the current total amount of bandwidth requested for this service queue including appropriate allowance for the PHY overhead.
+
+![Diagram of Request MAC Header format showing fields FC (1 byte), MAC_PARM (1 byte), SID (2 bytes), and HCS (2 bytes). The FC field is expanded to show FC_TYPE = 11, FC_PARM = R0010, and EHDR_ON = 0. Reference T0904960-97/d067.](69d00e8adf9811292427fb2ce6712e39_img.jpg)
+
+Diagram of Request MAC Header format showing fields FC (1 byte), MAC\_PARM (1 byte), SID (2 bytes), and HCS (2 bytes). The FC field is expanded to show FC\_TYPE = 11, FC\_PARM = R0010, and EHDR\_ON = 0. Reference T0904960-97/d067.
+
+Figure B.6-9/J.112 – Request MAC Header format
+
+Table B.6-8/J.112 – Request MAC Header (REQ) format
+
+| Field    | Usage                                                                                                                                                                                                                                                  | Size    |
+|----------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------|
+| FC       | FC_TYPE = 11; MAC-specific Header.<br>FC_PARM[3:0] = 0010; MAC Header only; no data PDU following.<br>FC_PARM[4] indicates if REQ is in mini-slots or ATM cells.<br>[4] = 0; mini-slot REQ.<br>[4] = 1; ATM cell REQ.<br>EHDR_ON = 0; no EHDR allowed. | 8 bits  |
+| MAC_PARM | REQ, total amount of bandwidth requested (upstream only):<br>if FC_PARM[4] = 0; REQ is number of mini-slots.<br>if FC_PARM[4] = 1; REQ is number of ATM cells.                                                                                         | 8 bits  |
+| SID      | Service ID (0 ...0x3FFF)                                                                                                                                                                                                                               | 16 bits |
+| EHDR     | Extended MAC Header not allowed                                                                                                                                                                                                                        | 0 bytes |
+| HCS      | MAC Header check sequence                                                                                                                                                                                                                              | 2 bytes |
+|          | Length of a REQ MAC Header                                                                                                                                                                                                                             | 6 bytes |
+
+**B.6.2.5.4 Concatenation**
+
+A Specific MAC Header is defined to allow multiple MAC frames to be concatenated. This allows a single MAC "burst" to be transferred across the network. The PHY overhead and the Concatenation MAC Header only occur once. Concatenation of multiple MAC frames MUST be as shown in Figure B.6-10.
+
+A compliant CMTS & CM MAY support concatenation.
+
+NOTE – Concatenation only applies to upstream traffic. Concatenation MUST NOT be used on downstream traffic.
+
+![Diagram of Concatenation of multiple MAC frames showing PHY Overhead, MAC Hdr (Concat), MAC Frame 1 (MAC HDR + optional PDU), and MAC Frame n (MAC HDR + optional PDU). Reference T0906030-97/d068.](7e96b46e088584838469f51c1d8d16da_img.jpg)
+
+Diagram of Concatenation of multiple MAC frames showing PHY Overhead, MAC Hdr (Concat), MAC Frame 1 (MAC HDR + optional PDU), and MAC Frame n (MAC HDR + optional PDU). Reference T0906030-97/d068.
+
+Figure B.6-10/J.112 – Concatenation of multiple MAC frames
+
+Only one Concatenation MAC Header MUST be present per MAC "burst". Nested concatenation MUST NOT be allowed. Immediately following the Concatenation MAC Header MUST be the MAC Header of the first MAC Frame. Information within the MAC Header indicates the length of the first MAC Frame and provides a means to find the start of the next MAC Frame. Each MAC Frame within a concatenation MUST be unique and MAY be of any type. This means that Packet, ATM, Reserved PDU and MAC-specific frames MAY be mixed together. The embedded MAC frames MAY be addressed to different destinations and MUST be delivered as if they were transmitted individually.
+
+The format of the Concatenation MAC Header MUST be as shown in Figure B.6-11 and Table B.6-9.
+
+The MAC\_PARM field MUST be used to indicate the total count of MAC frames (CNT) in this concatenation burst. If the count equals zero, then there is an unspecified number of MAC frames. The LEN field indicates the length of the entire concatenation. This is slightly different than the LEN field within an individual MAC Header which only indicates the length of that MAC frame.
+
+![Diagram of Concatenation MAC Header format. The header consists of four fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), and HCS (2 bytes). The FC field is expanded to show its internal structure: FC_TYPE = 11, FC_PARM = 11100, and EHDR_ON = 0. A dashed line connects the FC field to its expanded view. A label T0904970-97/d069 is present below the HCS field.](93bd00a00fa28558486f0664550699b1_img.jpg)
+
+Diagram of Concatenation MAC Header format. The header consists of four fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), and HCS (2 bytes). The FC field is expanded to show its internal structure: FC\_TYPE = 11, FC\_PARM = 11100, and EHDR\_ON = 0. A dashed line connects the FC field to its expanded view. A label T0904970-97/d069 is present below the HCS field.
+
+**Figure B.6-11/J.112 – Concatenation MAC Header format**
+
+**Table B.6-9/J.112 – Concatenated MAC Frame format**
+
+| Field       | Usage                                                                                                                                 | Size          |
+|-------------|---------------------------------------------------------------------------------------------------------------------------------------|---------------|
+| FC          | FC_TYPE = 11; MAC-specific Header<br>FC_PARM[4:0] = 11100; Concatenation MAC Header<br>EHDR_ON = 0; no EHDR with Concatenation Header | 8 bits        |
+| MAC_PARM    | CNT, number of MAC frames in this concatenation<br>CNT = 0 indicates unspecified number of MAC frames                                 | 8 bits        |
+| LEN         | LEN = x + ... + y; length of all following MAC frames in bytes                                                                        | 16 bits       |
+| EHDR        | Extended MAC Header MUST NOT be used                                                                                                  | 0 bytes       |
+| HCS         | MAC Header check sequence                                                                                                             | 2 bytes       |
+| MAC Frame 1 | first MAC frame: MAC Header plus OPTIONAL data PDU                                                                                    | x bytes       |
+| MAC Frame n | last MAC frame: MAC Header plus OPTIONAL data PDU                                                                                     | y bytes       |
+|             | Length of Concatenated MAC Frame                                                                                                      | 6 + LEN bytes |
+
+### B.6.2.6 Extended MAC headers
+
+Every MAC Header, except the Timing, Concatenation MAC Header and Request Frame, has the capability of defining an Extended Header field (EHDR). The presence of an EHDR field MUST be indicated by the EHDR\_ON flag in the FC field being set. Whenever this bit is set, then the MAC\_PARM field MUST be used as the EHDR length (ELEN). The minimum defined EHDR is 1 byte. The maximum EHDR length is 240 bytes.
+
+A compliant CMTS & CM MUST support extended headers.
+
+The format of a generic MAC Header with an Extended Header included MUST be as shown in Figure B.6-12 and Table B.6-10.
+
+NOTE – Extended Headers MUST NOT be used in a Concatenation MAC Header, but MAY be included as part of the MAC headers within the concatenation.
+
+Extended headers MUST NOT be used in Request and Timing MAC headers.
+
+![Figure B.6-12/J.112 – Extended MAC format diagram. The top part shows a MAC frame structure: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), EHDR (1-240 bytes), HCS (2 bytes), and data PDU (optional). Below this, two callouts show detailed field structures. The first callout for the FC field shows FC_TYPE = XX, FC_PARM (reserved), and EHDR_ON = 1. The second callout for the EHDR field shows a repeating structure of EH_TYPE (4 bits), EH_LEN (4 bits), EH_VALUE (0-15 bytes), and a 'repeat' indicator. A small code T0906450-98/d070 is visible at the bottom right.](dbf5c0f3c7836f717d9fe62c6c40b280_img.jpg)
+
+Figure B.6-12/J.112 – Extended MAC format diagram. The top part shows a MAC frame structure: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), EHDR (1-240 bytes), HCS (2 bytes), and data PDU (optional). Below this, two callouts show detailed field structures. The first callout for the FC field shows FC\_TYPE = XX, FC\_PARM (reserved), and EHDR\_ON = 1. The second callout for the EHDR field shows a repeating structure of EH\_TYPE (4 bits), EH\_LEN (4 bits), EH\_VALUE (0-15 bytes), and a 'repeat' indicator. A small code T0906450-98/d070 is visible at the bottom right.
+
+Figure B.6-12/J.112 – Extended MAC format
+
+Table B.6-10/J.112 – Extended Header format
+
+| Field    | Usage                                                                                                                                  | Size            |
+|----------|----------------------------------------------------------------------------------------------------------------------------------------|-----------------|
+| FC       | FC_TYPE = XX; applies to all MAC Headers.<br>FC_PARM[4:0] = XXXXX; dependent on FC_TYPE.<br>EHDR_ON = 1; EHDR present in this example. | 8 bits          |
+| MAC_PARM | ELEN = x; length of EHDR in bytes.                                                                                                     | 8 bits          |
+| LEN      | LEN = x + y; length of EHDR plus OPTIONAL data PDU in bytes.                                                                           | 16 bits         |
+| EHDR     | Extended MAC Header present in this example                                                                                            | x bytes         |
+| HCS      | MAC Header check sequence                                                                                                              | 2 bytes         |
+| PDU      | OPTIONAL data PDU                                                                                                                      | y bytes         |
+|          | Length of MAC Frame with EHDR                                                                                                          | 6 + x + y bytes |
+
+Since the EHDR increases the length of the MAC frame, the LEN field MUST be increased to include both the length of the Data PDU and the length of the EHDR.
+
+The EHDR field consists of one or more EH elements. Each EH element is variable sized. The first byte of the EH element MUST contain a type and a length field. Every CM MUST use this length to skip over any unknown EH elements. The format of an EH element MUST be as shown in Table B.6-11.
+
+Table B.6-11/J.112 – EH element format
+
+| EH element fields | Usage                 | Size       |
+|-------------------|-----------------------|------------|
+| EH_TYPE           | EH element type field | 4 bits     |
+| EH_LEN            | Length of EH_VALUE    | 4 bits     |
+| EH_VALUE          | EH element data       | 0-15 bytes |
+
+The types of EH element defined in Table B.6-12 MUST be supported. Reserved and extended types are undefined at this point and SHOULD be ignored.
+
+The first eight EH element types are intended for one-way transfer between the cable modem and the CMTS. The next seven EH element types are for end-to-end usage within a MAC-sublayer domain. Thus, the information attached to the EHDR on the upstream MUST also be attached when the information is forwarded. The final EH element type is an escape mechanism that allows for more types and longer values, and MUST be as shown in Table B.6-12.
+
+**Table B.6-12/J.112 – EH element format**
+
+| <b>EH_TYPE</b> | <b>EH_LEN</b> | <b>EH_VALUE</b>                                                                                                                             |
+|----------------|---------------|---------------------------------------------------------------------------------------------------------------------------------------------|
+| 0              | 0             | Null configuration setting: may be used to pad the extended header. The EH_LEN MUST be zero, but the configuration setting may be repeated. |
+| 1              | 3             | Request: mini-slots requested (1 byte); SID (2 bytes) [CM → CMTS].                                                                          |
+| 2              | 2             | Acknowledgment requested; SID (2 bytes) [CM → CMTS].                                                                                        |
+| 3 (= BP_UP)    | 4             | Upstream Privacy EH element [MCNS8]                                                                                                         |
+| 4 (= BP_DOWN)  | 4             | Downstream Privacy EH element [MCNS8]                                                                                                       |
+| 5 (= SS_UP)    | 8 or 9        | Upstream Security Header [MCNS2]                                                                                                            |
+| 6 (= SS_DOWN)  | 8 or 9        | Downstream Security Header [MCNS2]                                                                                                          |
+| 7              |               | Reserved                                                                                                                                    |
+| 8              | 4             | Reserved                                                                                                                                    |
+| 10-14          |               | Reserved [CM ↔ CM]                                                                                                                          |
+| 15             | XX            | Extended EH element: EHX_TYPE (1 byte), EHX_LEN (1 byte), EH_VALUE (length determined by EHX_LEN).                                          |
+
+### B.6.2.7 Error-Handling
+
+The cable network is a potentially harsh environment that may cause several different error conditions to occur. This subclause, together with B.7.2.17, describes the procedures that are required when an exception occurs at the MAC framing level.
+
+The most obvious type of error occurs when the HCS on the MAC Header fails. This may be a result of noise on the network or possibly by collisions in the upstream channel. Framing recovery on the downstream channel is performed by the MPEG transmission convergence sublayer. In the upstream channel, framing is recovered on each transmitted burst, such that framing on one burst is independent of framing on prior bursts. Hence, framing errors within a burst are handled by simply ignoring that burst, i.e. errors are unrecoverable until the next burst.
+
+A second exception, which applies only to the upstream, occurs when the Length field is corrupted and the MAC thinks the frame is longer than it actually is. Synchronization will recover at the next valid upstream data interval.
+
+For every MAC transmission, the HCS MUST be verified. When a bad HCS is detected, the MAC Header and any payload MUST be dropped.
+
+For Packet PDU transmissions, a bad CRC MAY be detected. Since the CRC only covers the Data PDU and the HCS covers the MAC Header; the MAC Header is still considered valid. Thus, the Packet PDU MUST be dropped, but any pertinent information in the MAC Header (e.g. bandwidth request information) MAY be used.
+
+## B.6.3 MAC Management messages
+
+### B.6.3.1 MAC Management message Header
+
+MAC management messages MUST be encapsulated in an LLC unnumbered information frame per [ISO/IEC 8802-2], which in turn is encapsulated within the cable network MAC framing, as shown in Figure B.6-13. Figure B.6-13 shows the MAC Header and the MAC Management Message Header fields which are common across all MAC Management messages.
+
+![Diagram of MAC Header and MAC Management Message Header fields. The diagram shows the bit layout from 0 to 31. The MAC Header (bits 0-15) contains FC (0-7), MAC_PARM (8-15), LEN (16-23), and HCS (24-31). The MAC Management Message Header (bits 16-31) contains DA (16-23), DA (24-31), SA (32-39), msg LEN (40-47), DSAP (48-55), SSAP (56-63), control (64-71), version (72-79), type (80-87), RSVD (88-95), Management message payload (variable length), and CRC (end). Labels on the right indicate the MAC Header, MAC Management Message Header, and Management message payload.](beda549cc2a4e2b9ac7f74fe9ed72b67_img.jpg)
+
+T0906460-98/d071
+
+Diagram of MAC Header and MAC Management Message Header fields. The diagram shows the bit layout from 0 to 31. The MAC Header (bits 0-15) contains FC (0-7), MAC\_PARM (8-15), LEN (16-23), and HCS (24-31). The MAC Management Message Header (bits 16-31) contains DA (16-23), DA (24-31), SA (32-39), msg LEN (40-47), DSAP (48-55), SSAP (56-63), control (64-71), version (72-79), type (80-87), RSVD (88-95), Management message payload (variable length), and CRC (end). Labels on the right indicate the MAC Header, MAC Management Message Header, and Management message payload.
+
+**Figure B.6-13/J.112 – MAC Header and MAC Management Message Header fields**
+
+The fields MUST be as defined below:
+
+|                                   |                                                                                                                                                                                          |
+|-----------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| <b>FC, MAC_PARM, LEN, HCS</b>     | Common MAC frame header – Refer to B.6.2.1.4 for details. All messages use a MAC-specific header.                                                                                        |
+| <b>Destination Address (DA)</b>   | MAC management frames will be addressed to a specific CM unicast address or to the MCNS management multicast address. These MCNS MAC management addresses are described in Appendix B.I. |
+| <b>Source Address (SA)</b>        | The MAC address of the source CM or CMTS system.                                                                                                                                         |
+| <b>Msg Length</b>                 | Length of the MAC message from DSAP to the end of the payload.                                                                                                                           |
+| <b>DSAP</b>                       | The LLC null SAP (00) as defined by [ISO/IEC 8802-2].                                                                                                                                    |
+| <b>SSAP</b>                       | The LLC null SAP (00) as defined by [ISO/IEC 8802-2].                                                                                                                                    |
+| <b>Control</b>                    | Unnumbered information frame (03) as defined by [ISO/IEC 8802-2].                                                                                                                        |
+| <b>Version</b>                    | 1 octet<br>This field defines the version of the MAC management protocol in use. Set to 1 for this version.                                                                              |
+| <b>Type</b>                       | 1 octet<br>This field defines the type of this particular MAC management message.                                                                                                        |
+| <b>RSVD</b>                       | 1 octet<br>This field is used to align the message payload on a 32-bit boundary. Set to 0 for this version.                                                                              |
+| <b>Management Message Payload</b> | Variable length<br>As defined for each specific management message.                                                                                                                      |
+| <b>CRC</b>                        | Covers message including header fields (DA, SA, ...). Polynomial defined by [ISO/IEC 8802-3].                                                                                            |
+
+**Table B.6-13/J.112 – MAC Management message types**
+
+| Type value | Message name | Message description                     |
+|------------|--------------|-----------------------------------------|
+| 1          | SYNC         | Timing Synchronization                  |
+| 2          | UCD          | Upstream Channel Descriptor             |
+| 3          | MAP          | Upstream Bandwidth Allocation           |
+| 4          | RNG-REQ      | Ranging Request                         |
+| 5          | RNG-RSP      | Ranging Response                        |
+| 6          | REG-REQ      | Registration Request                    |
+| 7          | REG-RSP      | Registration Response                   |
+| 8          | UCC-REQ      | Upstream Channel Change Request         |
+| 9          | UCC-RSP      | Upstream Channel Change Response        |
+| 10         | TRI-TCD      | Telephony Channel Descriptor [MCNS6]    |
+| 11         | TRI-TSI      | Termination System Information [MCNS6]  |
+| 12         | BPKM-REQ     | Privacy Key Management Request [MCNS8]  |
+| 13         | BPKM-RSP     | Privacy Key Management Response [MCNS8] |
+| 14-255     |              | Reserved for future use                 |
+
+**B.6.3.2 MAC management messages**
+
+A compliant CMTS or CM MUST support the following management message types.
+
+**B.6.3.2.1 Time Synchronization (SYNC)**
+
+Time Synchronization (SYNC) MUST be transmitted by CMTS at a periodic interval to establish MAC sublayer timing. This message MUST use an FC field of type: Timing. This MUST be followed by a Packet PDU in the format shown in Figure B.6-14.
+
+![Diagram showing the format of a Packet PDU following the timing Header. It consists of two stacked rectangular boxes. The top box is labeled 'MAC Management Message Header' and the bottom box is labeled 'CMTS Timestamp'. Above the boxes, bit positions 0, 8, 16, 24, and 31 are marked. A small code 'T0906470-98/d072' is at the bottom right.](8d9be1ac4372e563dc3eb6d4aa5690d6_img.jpg)
+
+Diagram showing the format of a Packet PDU following the timing Header. It consists of two stacked rectangular boxes. The top box is labeled 'MAC Management Message Header' and the bottom box is labeled 'CMTS Timestamp'. Above the boxes, bit positions 0, 8, 16, 24, and 31 are marked. A small code 'T0906470-98/d072' is at the bottom right.
+
+**Figure B.6-14/J.112 – Format of Packet PDU following the timing Header**
+
+The parameters shall be as defined below:
+
+**CMTS Timestamp** An incrementing 32-bit timestamp based on a timebase reference clock at the CMTS. Units are in 1/64th of a Timebase Tick (i.e. 6.25/64 μs<sup>4</sup>).
+
+<sup>4</sup> Since the SYNC message applies to all upstream channels within this MAC domain, units were chosen to be independent of the symbol rate of any particular upstream channel. A Timebase Tick represents the smallest possible mini-slot at the highest possible symbol rate. See B.6.5.4 for time-unit relationships.
+
+### B.6.3.2.2 Upstream Channel Descriptor (UCD)
+
+An Upstream Channel Descriptor MUST be transmitted by the CMTS at a periodic interval to define the characteristics of an upstream channel (see Figure B.6-15). A separate message MUST be transmitted for each active upstream.
+
+![Diagram of the Upstream Channel Descriptor (UCD) message structure showing bit offsets and field layout.](4b9e2f848d66a0b3c2d4553b965933c7_img.jpg)
+
+|                                                              |                               |                   |                          |    |
+|--------------------------------------------------------------|-------------------------------|-------------------|--------------------------|----|
+| Bit 0                                                        | 8                             | 16                | 24                       | 31 |
+| MAC Management<br>Message Header                             |                               |                   |                          |    |
+| Upstream<br>channel ID                                       | Configuration<br>Change Count | Mini-Slot<br>Size | Downstream<br>channel ID |    |
+| TLV-encoded information for the overall<br>channel           |                               |                   |                          |    |
+| TLV-encoded burst<br>description                             |                               |                   |                          |    |
+| TLV-encoded information for the subsequent burst descriptors |                               |                   |                          |    |
+
+T0906480-98/d073
+
+Diagram of the Upstream Channel Descriptor (UCD) message structure showing bit offsets and field layout.
+
+**Figure B.6-15/J.112 – Upstream channel descriptor**
+
+To provide for flexibility, the message parameters following the channel ID MUST be encoded in a Type/Length/Value (TLV) form in which the type and length fields are each 1 octet long. Using this encoding, new parameters MAY be added which not all CMs can interpret. A CM which does not recognize a parameter type MUST skip over this parameter and MUST NOT treat the event as an error condition.
+
+A CMTS MUST generate UCDs in the format shown in Figure B.6-15, including all of the following parameters:
+
+- Configuration Change Count** Incremented by one (modulo the field size) by the CMTS whenever any of the values of this channel descriptor change. If the value of this count in a subsequent UCD remains the same, the CM can quickly decide that the remaining fields have not changed, and may be able to disregard the remainder of the message. This value is also referenced from the MAP.
+- Mini-Slot Size** The size  $T$  of the Mini-Slot for this upstream channel in units of the Timebase Tick of 6.25  $\mu\text{s}$ . Allowable values are  $T = 2^M$ ,  $M = 0, 1, \dots, 7$ . That is,  $T = 1, 2, 4, 8, 16, 32, 64, \text{ or } 128$ .
+- upstream channel ID** The identifier of the upstream channel to which this message refers. This identifier is arbitrarily chosen by the CMTS and is only unique within the MAC-sublayer domain.
+- downstream channel ID** The identifier of the downstream channel on which this message has been transmitted. This identifier is arbitrarily chosen by the CMTS and is only unique within the MAC-sublayer domain.
+
+All other parameters are coded as TLV tuples. Channel-wide parameters (types 1-3 in Table B.6-14) must precede burst descriptors (type 4 below).
+
+**Table B.6-14/J.112 – Channel TLV parameters**
+
+| Name             | Type<br>(1 byte) | Length<br>(1 byte) | Value<br>(Variable length)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+|------------------|------------------|--------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Symbol Rate      | 1                | 1                  | Multiples of base rate of 160 ksym/s. (Value is 1, 2, 4, 8, or 16.)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
+| Frequency        | 2                | 4                  | Upstream center frequency (Hz)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
+| Preamble Pattern | 3                | 1-128              | Preamble superstring. All burst-specific preamble values are chosen as bit-substrings of this string.<br>The first byte of the Value field contains the first 8 bits of the superstring, with the first bit of the preamble superstring in the MSB position of the first Value field byte, the eighth bit of the preamble superstring in the LSB position of the first Value field byte; the second byte in the Value field contains the second eight bits of the superstring, with the ninth bit of the superstring in the MSB of the second byte and sixteenth bit of the preamble superstring in the LSB of the second byte, and so forth. |
+| Burst Descriptor | 4                |                    | May appear more than once; described below. The length is the number of bytes in the overall object, including embedded TLV items.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
+
+Burst Descriptors are compound TLV encodings that define, for each type of upstream usage interval, the physical-layer characteristics that are to be used during that interval. The upstream interval usage codes are defined in the MAP message (see B.6.3.2.3 and Figure B.6-16).
+
+![Diagram showing the top-level encoding for a Burst Descriptor. It consists of three fields: 'Type = 4 Burst Descriptor', 'Length 1-n', and 'Interval Usage Code'. Below these fields is a dashed box labeled 'TLV codes for PHY parameters'. The diagram is labeled T0906490-98/d074.](ceb6fe29e2d57711907569c31182b3c2_img.jpg)
+
+|                              |               |                        |
+|------------------------------|---------------|------------------------|
+| Type = 4<br>Burst Descriptor | Length<br>1-n | Interval Usage<br>Code |
+| TLV codes for PHY parameters |               |                        |
+
+T0906490-98/d074
+
+Diagram showing the top-level encoding for a Burst Descriptor. It consists of three fields: 'Type = 4 Burst Descriptor', 'Length 1-n', and 'Interval Usage Code'. Below these fields is a dashed box labeled 'TLV codes for PHY parameters'. The diagram is labeled T0906490-98/d074.
+
+**Figure B.6-16/J.112 – Top-level encoding for a Burst Descriptor**
+
+A Burst Descriptor MUST be included for each interval usage code that is to be used in the allocation MAP. The interval usage code above must be one of the values from Table B.6-16.
+
+Within each Burst Descriptor is an unordered list of Physical-layer attributes, encoded as TLV values. These attributes are shown in Table B.6-15.
+
+#### B.6.3.2.2.1 Example of UCD encoded TLV data
+
+An example of UCD encoded TLV data is given in Figure B.6-17.
+
+**Table B.6-15/J.112 – Upstream Physical-Layer Burst Attributes**
+
+| <b>Name</b>                    | <b>Type<br/>(1 byte)</b> | <b>Length<br/>(1 byte)</b> | <b>Value<br/>(Variable Length)</b>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+|--------------------------------|--------------------------|----------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Modulation Type                | 1                        | 1                          | 1 = QPSK, 2 = 16 QAM                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
+| Differential Encoding          | 2                        | 1                          | 1 = on, 2 = off                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
+| Preamble Length                | 3                        | 2                          | Up to 1024 bits. The value must be an integral number of symbols (a multiple of 2 for QPSK and 4 for 16 QAM)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
+| Preamble Value Offset          | 4                        | 2                          | Identifies the bits to be used for the preamble value. This is specified as a starting offset into the Preamble Pattern (see Table B.6-14). That is, a value of zero means that the first bit of the preamble for this burst type is the value of the first bit of the Preamble Pattern. A value of 100 means that the preamble is to use the 101st and succeeding bits from the Preamble Pattern. This value must be a multiple of the symbol size. The first bit of the Preamble Pattern is the first bit into the symbol mapper (Figure B.4-8), and is I <sub>1</sub> in the first symbol of the burst (see B.4.2.2.2). |
+| FEC Error Correction (T bytes) | 5                        | 1                          | 0-10 bytes: zero implies no Forward Error Correction.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
+| FEC Codeword Length (k)        | 6                        | 1                          | Fixed: 16 to 253 (assuming FEC on)<br>Shortened: 16 to 253 (assuming FEC on)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
+| Scrambler Seed                 | 7                        | 2                          | The 15-bit seed value.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
+| Maximum Burst Size             | 8                        | 1                          | The maximum number of mini-slots that can be transmitted during this burst type. Absence of this configuration setting implies that the burst size is limited elsewhere. This value MUST be used when the interval type is Short Data Grant.                                                                                                                                                                                                                                                                                                                                                                               |
+| Guard Time Size                | 9                        | 1                          | Number of symbol times which must follow the end of this burst. (Although this value may be derivable from other network and architectural parameters, it is included here to ensure that the CMs and CMTS all use the same value.)                                                                                                                                                                                                                                                                                                                                                                                        |
+| Last Codeword Length           | 10                       | 1                          | 1 = fixed; 2 = shortened.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
+| Scrambler on/off               | 11                       | 1                          | 1 = on; 2 = off.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
+
+|        |              |                         |  |  |
+|--------|--------------|-------------------------|--|--|
+| Type 1 | Length 1     | Symbol Rate             |  |  |
+| Type 2 | Length 4     | Frequency               |  |  |
+| Type 3 | Length 1-128 | Preamble Superstring    |  |  |
+| Type 4 | Length N     | First Burst Descriptor  |  |  |
+| Type 4 | Length N     | Second Burst Descriptor |  |  |
+| Type 4 | Length N     | Third Burst Descriptor  |  |  |
+| Type 4 | Length N     | Fourth Burst Descriptor |  |  |
+
+T0905860-97/d075
+
+Figure B.6-17/J.112 – Example of UCD encoded TLV data
+
+**B.6.3.2.3 Upstream Bandwidth Allocation Map (MAP)**
+
+A CMTS MUST generate MAPs in the format shown in Figure B.6-18.
+
+![Diagram of MAP format showing MAC Management Message Header, Upstream channel ID, UCD count, Number of elements, Reserved, Alloc start time, Ack time, Ranging back-off start/end, Data back-off start/end, and MAP information elements.](353d05a4935a6b770e9b80ed94762b6a_img.jpg)
+
+|                               |                      |                     |                   |
+|-------------------------------|----------------------|---------------------|-------------------|
+| MAC Management Message Header |                      |                     |                   |
+| Upstream channel ID           | UCD count            | Number of elements  | Reserved          |
+| Alloc start time              |                      |                     |                   |
+| Ack time                      |                      |                     |                   |
+| Ranging back-off start        | Ranging back-off end | Data back-off start | Data back-off end |
+| MAP information elements      |                      |                     |                   |
+
+Diagram of MAP format showing MAC Management Message Header, Upstream channel ID, UCD count, Number of elements, Reserved, Alloc start time, Ack time, Ranging back-off start/end, Data back-off start/end, and MAP information elements.
+
+T0906500-98/d076
+
+Figure B.6-18/J.112 – MAP format
+
+The parameters MUST be as follows:
+
+|                            |                                                                                                                                            |
+|----------------------------|--------------------------------------------------------------------------------------------------------------------------------------------|
+| <b>Upstream Channel ID</b> | The identifier of the upstream channel to which this message refers.                                                                       |
+| <b>UCD Count</b>           | Matches the value of the Configuration Change Count of the UCD which describes the burst parameters which apply to this map. See B.7.2.15. |
+| <b>Number Elements</b>     | Number of information elements in the map.                                                                                                 |
+| <b>Reserved</b>            | Reserved field for alignment.                                                                                                              |
+
+|                                 |                                                                                                                                                                |
+|---------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| <b>Alloc Start Time</b>         | Effective start time from CMTS initialization (in mini-slots) for assignments within this map.                                                                 |
+| <b>Ack Time</b>                 | Latest time, from CMTS initialization, (mini-slots) processed in upstream. This time is used by the CMs for collision detection purposes. See B.6.4.4.         |
+| <b>Ranging Backoff Start</b>    | Initial back-off window for initial ranging contention, expressed as a power of two. Values range 0-15 (the highest order bits must be unused and set to 0).   |
+| <b>Ranging Backoff End</b>      | Final back-off window for initial ranging contention, expressed as a power of two. Values range 0-15 (the highest order bits must be unused and set to 0).     |
+| <b>Data Backoff Start</b>       | Initial back-off window for contention data and requests, expressed as a power of two. Values range 0-15 (the highest order bits must be unused and set to 0). |
+| <b>Data Backoff End</b>         | Final back-off window for contention data and requests, expressed as a power of two. Values range 0-15 (the highest order bits must be unused and set to 0).   |
+| <b>MAP information elements</b> | MUST be in the format defined in Figure B.6-19 and Table B.6-16. Values for IUCs are defined in Table B.6-16 and are described in detail in B.6.4.1.           |
+
+![Diagram showing the MAP information element structure with columns for SID, IUC, and Offset. Rows include First interval, Second interval, Last interval, End-of-list (Null IE), and Acknowledgements and Deferrals.](c80e1284549c9914d0249b0e749c500a_img.jpg)
+
+|                                |         |         |                     |
+|--------------------------------|---------|---------|---------------------|
+| First interval                 | SID     | IUC     | Offset = 0          |
+| Second interval                | SID     | IUC     | Offset              |
+| ⋮                              |         |         |                     |
+| Last interval                  | SID     | IUC     | Offset              |
+| End-of-list (Null IE)          | SID = 0 | IUC = 7 | Offset = map length |
+|                                | SID     | IUC     | Offset = map length |
+| ⋮                              |         |         |                     |
+| Acknowledgements and Deferrals | SID     | IUC     | Offset = map length |
+
+Diagram showing the MAP information element structure with columns for SID, IUC, and Offset. Rows include First interval, Second interval, Last interval, End-of-list (Null IE), and Acknowledgements and Deferrals.
+
+T0905030-97/d077
+
+**Figure B.6-19/J.112 – MAP information element structure**
+
+**Table B.6-16/J.112 – Allocation MAP Information Elements (IE)**
+
+| IE name                                                   | Interval Usage Code (IUC) (4 bits) | SID (14 bits)       | Mini-slot offset (14 bits)                                                                            |
+|-----------------------------------------------------------|------------------------------------|---------------------|-------------------------------------------------------------------------------------------------------|
+| Request                                                   | 1                                  | Any                 | Starting offset of REQ region                                                                         |
+| REQ/Data (refer to Appendix B.1 for multicast definition) | 2                                  | Multicast           | Starting offset of IMMEDIATE Data region<br>Well-known multicasts define start intervals              |
+| Initial Maintenance                                       | 3                                  | Broadcast/multicast | Starting offset of MAINT region (used in Initial Ranging)                                             |
+| Station Maintenance (Note 1)                              | 4                                  | Unicast             | Starting offset of MAINT region (used in Periodic Ranging)                                            |
+| Short Data Grant (Note 2)                                 | 5                                  | Unicast             | Starting offset of Data Grant assignment;<br>If inferred length = 0, then it is a Data Grant pending. |
+| Long Data Grant                                           | 6                                  | Unicast             | Starting offset of Data Grant assignment;<br>If inferred length = 0, then it is a Data Grant pending. |
+| Null IE                                                   | 7                                  | Zero                | Ending offset of the previous grant. Used to bound the length of the last actual interval allocation. |
+| Data Ack                                                  | 8                                  | Unicast             | CMTS sets to 0.                                                                                       |
+| Reserved                                                  | 9-14                               | Any                 | Reserved                                                                                              |
+| Expansion                                                 | 15                                 | Expanded IUC        | # of additional 32-bit words in this IE                                                               |
+
+NOTE 1 – Although the distinction between Initial Maintenance and Station Maintenance is unambiguous from the Service ID type, separate codes are used to ease physical-layer configuration (see burst descriptor encodings, Table B.6-15).  
+NOTE 2 – The distinction between long and short data grants is related to the amount of data that can be transmitted in the grant. A short data grant interval may use FEC parameters that are appropriate to short packets while a long data grant may be able to take advantage of greater FEC coding efficiency.  
+NOTE 3 – Each IE is a 32-bit quantity, of which the most significant 14 bits represent the SID, the middle 4 bits the IUC, and the low-order 14 bits the mini-slot offset.  
+NOTE 4 – The SID used in the Station Maintenance IE MUST be a Temporary SID, or the first Registration SID (and maybe the only one) that was assigned in the REG-RSP message to a CM.
+
+**B.6.3.2.4 Ranging Request (RNG-REQ)**
+
+A Ranging Request MUST be transmitted by a CM at initialization and periodically on request from CMTS to determine network delay. This message MUST use an FC field of type: Timing. This MUST be followed by a Packet PDU in the format shown in Figure B.6-20.
+
+![Diagram of Packet PDU following the Timing Header. It shows a 32-bit word structure with bit positions 0, 8, 16, 24, and 31. The first 16 bits (0-15) are the MAC Management Message Header. The next 8 bits (16-23) are the SID. The following 8 bits (24-31) are split into Downstream channel ID (bits 24-27) and Pending till complete (bits 28-31).](3d590ad29ecfe728f07432e6fcb59064_img.jpg)
+
+Bit 0 8 16 24 31
+
+|                               |  |                       |                       |
+|-------------------------------|--|-----------------------|-----------------------|
+| MAC Management Message Header |  |                       |                       |
+| SID                           |  | Downstream channel ID | Pending till complete |
+
+T0906510-98/d078
+
+Diagram of Packet PDU following the Timing Header. It shows a 32-bit word structure with bit positions 0, 8, 16, 24, and 31. The first 16 bits (0-15) are the MAC Management Message Header. The next 8 bits (16-23) are the SID. The following 8 bits (24-31) are split into Downstream channel ID (bits 24-27) and Pending till complete (bits 28-31).
+
+**Figure B.6-20/J.112 – Packet PDU following the Timing Header**
+
+Parameters MUST be as follows:
+
+**SID**
+
+For RNG-REQ messages transmitted in Initial Maintenance intervals:
+
+- initialization SID if modem is attempting to join the network;
+- initialization SID if modem has not yet registered and is changing downstream (or both downstream and upstream) channels as directed by a downloaded parameter file;
+- temporary SID if modem has not yet registered and is changing upstream (not downstream) channels as directed by a downloaded parameter file;
+- registration SID (previously assigned in REG-RSP) if modem is registered and is changing upstream channels.
+
+For RNG-REQ messages transmitted in Station Maintenance intervals:
+
+- assigned SID.
+
+This is a 16-bit field of which the lower 14 bits define the SID with bits 14, 15 defined to be 0.
+
+**Downstream channel ID**
+
+The identifier of the downstream channel on which the CM received the UCD which described this upstream. This is an 8-bit field.
+
+**Pending Till Complete**
+
+If zero, then all previous Ranging Response attributes have been applied prior to transmitting this request. If non-zero, then this is time estimated to be needed to complete assimilation of ranging parameters. Note that only equalization can be deferred. Units are in unsigned centiseconds (10 ms).
+
+**B.6.3.2.5 Ranging Response (RNG-RSP)**
+
+A Ranging Response MUST be transmitted by a CMTS in response to received RNG-REQ in the format shown in Figure B.6-21. The state machines describing the ranging procedure appear in B.7.2.5. In that procedure it may be noted that, from the point of view of the CM, reception of a Ranging Response is stateless. In particular, the CM MUST be prepared to receive a Ranging Response at any time, not just following a Ranging Request.
+
+![Diagram of Ranging Response message structure showing MAC Management Message Header, SID from request, Upstream channel ID, and TLV encoded information.](415ba50c9d9d7764be52dfed39f6ae43_img.jpg)
+
+The diagram illustrates the structure of a Ranging Response message. It is a 32-bit (4-byte) packet. The first byte (bits 0-7) is the MAC Management Message Header. The next byte (bits 8-15) is the SID from request. The third byte (bits 16-23) is the Upstream channel ID. The final byte (bits 24-31) is TLV encoded information. Bit positions 0, 8, 16, 24, and 31 are marked at the top.
+
+|                               |   |                     |    |                         |    |
+|-------------------------------|---|---------------------|----|-------------------------|----|
+| Bit                           | 0 | 8                   | 16 | 24                      | 31 |
+| MAC Management Message Header |   |                     |    |                         |    |
+| SID from request              |   | Upstream channel ID |    | TLV encoded information |    |
+|                               |   |                     |    |                         |    |
+
+T0906520-98/d079
+
+Diagram of Ranging Response message structure showing MAC Management Message Header, SID from request, Upstream channel ID, and TLV encoded information.
+
+**Figure B.6-21/J.112 – Ranging Response**
+
+To provide for flexibility, the message parameters following the Upstream Channel ID MUST be encoded in a type/length/value (TLV) form. Using this encoding, new parameters can be added which not all CMs can interpret. A CM which does not recognize a parameter type MUST simply skip over this parameter and MUST NOT treat the event as an error condition.
+
+Parameters MUST be as follows:
+
+|                                                |                                                                                                                                                                                                                                                                                                                                                          |
+|------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| <b>SID</b>                                     | If the modem is being instructed by this response to move to a different channel, this is initialization SID. Otherwise, this is the SID from the corresponding RNG-REQ to which this response refers, except that if the corresponding RNG-REQ was an initial ranging request specifying a initialization SID, then this is the assigned temporary SID. |
+| <b>Upstream channel ID</b>                     | The identifier of the upstream channel on which the CMTS received the RNG-REQ to which this response refers.                                                                                                                                                                                                                                             |
+| <b>Timing adjust information</b>               | The time by which to offset frame transmission so that frames arrive at the expected mini-slot time at the CMTS.                                                                                                                                                                                                                                         |
+| <b>Power adjust information</b>                | Specifies the relative change in transmission power level that the CM is to make in order that transmissions arrive at the CMTS at the desired power.                                                                                                                                                                                                    |
+| <b>Frequency adjust information</b>            | Specifies the relative change in transmission frequency that the CM is to make in order to better match the CMTS. (This is fine-frequency adjustment within a channel, not re-assignment to a different channel.)                                                                                                                                        |
+| <b>CM transmitter equalization information</b> | If the CM implements transmission equalization, this provides the equalization coefficients (optional).                                                                                                                                                                                                                                                  |
+| <b>Ranging status</b>                          | Used to indicate whether upstream messages are received within acceptable limits by CMTS.                                                                                                                                                                                                                                                                |
+| <b>Downstream Frequency Override</b>           | An optional parameter. The downstream frequency with which the modem should redo initial ranging.                                                                                                                                                                                                                                                        |
+| <b>Upstream Channel ID Override</b>            | An optional parameter. The identifier of the upstream channel with which the modem should redo initial ranging.                                                                                                                                                                                                                                          |
+
+#### B.6.3.2.5.1 Encodings
+
+The type values used MUST be those defined in Table B.6-17 and Figure B.6-22. These are unique within the ranging response message but not across the entire MAC message set. The type and length fields MUST each be 1 octet in length.
+
+**Table B.6-17/J.112 – Ranging Response message encodings**
+
+| Name                          | Type (1 byte) | Length (1 byte) | Value (Variable Length)                                            |
+|-------------------------------|---------------|-----------------|--------------------------------------------------------------------|
+| Timing Adjust                 | 1             | 4               | TX timing offset adjustment [signed 32 bit, units of (6.25 µs/64)] |
+| Power Level Adjust            | 2             | 1               | TX Power offset adjustment (signed 8 bit, 1/4-dB units)            |
+| Offset Frequency Adjust       | 3             | 2               | TX frequency offset adjustment (signed 16 bit, Hz units)           |
+| Transmit Equalization Adjust  | 4             | n               | TX equalization data – See details below                           |
+| Ranging Status                | 5             | 1               | 1 = continue, 2 = abort, 3 = success                               |
+| Downstream frequency override | 6             | 4               | Centre frequency of new downstream channel in Hz                   |
+| Upstream channel ID override  | 7             | 1               | Identifier of the new upstream channel                             |
+| Reserved                      | 8-255         | n               | Reserved for future use                                            |
+
+|                                        |                            |                                             |
+|----------------------------------------|----------------------------|---------------------------------------------|
+| Type<br>4                              | Length                     | Number of taps per symbol                   |
+| Number of forward taps (N)             | Number of reverse taps (M) |                                             |
+| First coefficient $F_0$ (real)         |                            | First coefficient $F_0$ (imaginary)         |
+| ~ ~                                    |                            |                                             |
+| Last coefficient $F_N$ (real)          |                            | Last coefficient $F_N$ (imaginary)          |
+| First reverse coefficient $D_0$ (real) |                            | First reverse coefficient $D_0$ (imaginary) |
+| ~ ~                                    |                            |                                             |
+| Last reverse coefficient $D_M$ (real)  |                            | Last reverse coefficient $D_M$ (imaginary)  |
+
+T0905060-97/d080
+
+**Figure B.6-22/J.112 – Generalized decision feedback equalization coefficients**
+
+The total number of taps per symbol MUST be in the range 1 to 4.
+
+The total number of taps MAY range up to 64. Each tap consists of a real and imaginary coefficient entry in the table.
+
+If more than 255 bytes are needed to represent equalization information, then several type-4 elements MAY be used. Data MUST be treated as if byte-concatenated, that is, the first byte after the length field of the second type-4 element is treated as if it immediately followed the last byte of the first type-4 element.
+
+The coefficients that are sent to the CM may be coefficients of a CMTS demodulator equalizer such as shown in Figure B.6-23, which, after acquisition, will have tap values that represent the channel distortion. Other equalization methods may be devised in the future. If so, they will use a different type-value so that the element is not overloaded. This is a vendor-specific issue which is not described here.
+
+![Block diagram of a CMTS demodulator equalizer showing tap locations for forward (F) and reverse (D) coefficients. The input signal is processed through a series of delay elements (z^-1) and summer nodes (+). Forward taps (F0, F1, F2, F3, F4, F5, ..., FN) are applied to the main signal path. Reverse taps (DM, ..., D5, D4, D3, D2, D1, D0) are applied to a feedback path that is delayed relative to the main path. The final output is the sum of the forward and reverse tap contributions.](66829132ebdbaebe4455fb6162ef7180_img.jpg)
+
+T0905070-97/d081
+
+Block diagram of a CMTS demodulator equalizer showing tap locations for forward (F) and reverse (D) coefficients. The input signal is processed through a series of delay elements (z^-1) and summer nodes (+). Forward taps (F0, F1, F2, F3, F4, F5, ..., FN) are applied to the main signal path. Reverse taps (DM, ..., D5, D4, D3, D2, D1, D0) are applied to a feedback path that is delayed relative to the main path. The final output is the sum of the forward and reverse tap contributions.
+
+**Figure B.6-23/J.112 – CMTS demodulator equalizer tap location definition**
+
+### B.6.3.2.5.2 Example of TLV data
+
+An example of TLV data is given in Figure B.6-24.
+
+|        |          |                                                    |  |
+|--------|----------|----------------------------------------------------|--|
+| Type 1 | Length 4 | Timing adjust                                      |  |
+| Type 2 | Length 1 | Power adjust                                       |  |
+| Type 3 | Length 2 | Frequency adjust information                       |  |
+| Type 4 | Length x | x bytes of CM transmitter equalization information |  |
+| Type 5 | Length 1 | Ranging status                                     |  |
+
+T0905080-97/d082
+
+Figure B.6-24/J.112 – Example of TLV data
+
+### B.6.3.2.5.3 Overriding channels
+
+The RNG-RSP message allows the CMTS to instruct the modem to move to a new downstream and/or upstream channel and to repeat initial ranging. However, the CMTS may do this only in response to an initial ranging request from a modem that is attempting to join the network, or in response to any of the unicast ranging requests that take place immediately after this initial ranging and up to the point where the modem successfully completes periodic ranging. From this point on, only Appendix B.III.8.4 and UCC-REQ mechanisms are available for moving the modem to a new upstream channel, and only Appendix B.III.8.3 mechanism is available for moving the modem to a new downstream channel.
+
+If a downstream frequency override is specified in the RNG-RSP, the modem MUST reinitialize its MAC and perform initial ranging using the specified downstream center frequency as the first scanned channel. For the upstream channel, the modem may select any valid channel based on received UCD messages.
+
+If an upstream channel ID override is specified in the RNG-RSP, the modem MUST reinitialize its MAC and perform initial ranging using for its first attempt the upstream channel specified in the RNG-RSP and the same downstream frequency on which the RNG-RSP was received.
+
+If both downstream frequency and upstream channel ID overrides are present in the RNG-RSP, the modem MUST reinitialize its MAC and perform initial ranging using for its first attempt the specified downstream frequency and upstream channel ID.
+
+Note that when a modem with an assigned temporary SID is instructed to move to a new downstream and/or upstream channel and to redo initial ranging, the modem MUST consider the temporary SID to be deassigned. The modem MUST redo initial ranging using the zero SID.
+
+Configuration file settings (see Appendix B.III.3) for upstream channel ID and downstream frequency are optional but, if specified in the configuration file, they take precedence over the ranging response parameters.
+
+### B.6.3.2.6 Registration Request (REG-REQ)
+
+A Registration Request, in the format shown in Figure B.6-25, MUST be transmitted by a CM at initialization after receipt of a CM parameter file.
+
+![Diagram of Registration Request message structure. The message is 32 bits (0-31) long. The first 32 bits are the MAC Management Message Header. The next 16 bits (0-15) are the SID. The remaining 16 bits (16-31) are TLV encoded information.](3eb2af31c2e61e2595c8440d726f5d4e_img.jpg)
+
+The diagram shows a 32-bit message structure. The top section is the 'MAC Management Message Header' spanning bits 0 to 31. Below it, the 'SID' field occupies bits 0 to 15. The bottom section, labeled 'TLV encoded information', occupies bits 16 to 31. A dashed line separates the header from the rest of the message. A small label 'T0906530-98/d083' is at the bottom right.
+
+Diagram of Registration Request message structure. The message is 32 bits (0-31) long. The first 32 bits are the MAC Management Message Header. The next 16 bits (0-15) are the SID. The remaining 16 bits (16-31) are TLV encoded information.
+
+**Figure B.6-25/J.112 – Registration Request**
+
+To provide for flexibility, the message parameters following the SID MUST be encoded in a type/length/value form. Using this encoding, new parameters MAY be added which not all CMTSs can interpret. A CMTS which does not recognize a parameter type MUST simply skip over this parameter and MUST not treat the event as an error condition.
+
+Parameters MUST be as follows:
+
+|                                              |                                                                                                                                                                                                                                                                                                                                                                                                                              |
+|----------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| <b>SID</b>                                   | Initialization SID for this CM.                                                                                                                                                                                                                                                                                                                                                                                              |
+| <b>Configuration settings for this modem</b> | As defined in Appendix B.III: <ul style="list-style-type: none"> <li>• downstream frequency configuration setting;</li> <li>• upstream channel ID configuration setting;</li> <li>• network access configuration setting;</li> <li>• class of service configuration setting;</li> <li>• modem capabilities configuration setting;</li> <li>• modem IP address;</li> <li>• baseline privacy configuration setting.</li> </ul> |
+| <b>Vendor-specific data</b>                  | As defined in Appendix B.III: <ul style="list-style-type: none"> <li>• vendor ID configuration setting (vendor ID of CM);</li> <li>• vendor-specific extensions.</li> </ul>                                                                                                                                                                                                                                                  |
+| <b>Message Integrity Checks</b>              | As defined in Appendix B.III: <ul style="list-style-type: none"> <li>• CM MIC configuration setting;</li> <li>• CMTS MIC configuration setting.</li> </ul>                                                                                                                                                                                                                                                                   |
+
+NOTE – The CM MUST be capable of supporting these standard configuration settings.
+
+#### **B.6.3.2.6.1 Encodings**
+
+The type values used are unique within the registration request message but not across the entire MAC message set. They MUST be those defined in Appendix B.III.
+
+NOTE – The CM MUST forward the vendor-specific configuration settings to the CMTS in the same order in which they were received in the configuration file to allow the message integrity check to be performed.
+
+**B.6.3.2.6.2 Example**
+
+An example of type value encodings is given in Figure B.6-26.
+
+|         |           |                                  |  |
+|---------|-----------|----------------------------------|--|
+| Type 1  | Length 4  | Downstream frequency             |  |
+| Type 2  | Length 1  | Upstream channel                 |  |
+| Type 3  | Length 1  | Network access                   |  |
+| Type 4  | Length 28 | Service class definition class 1 |  |
+| Type 4  | Length 28 | Service class definition class 2 |  |
+|         |           |                                  |  |
+| Type 4  | Length 28 | Service class definition class n |  |
+| Type 5  | Length 3  | Modem capabilities               |  |
+| Type 12 | Length 4  | Modem IP address                 |  |
+| Type 8  | Length 3  | Vendor ID                        |  |
+| Type 43 | Length n  | n bytes of vendor-specific data  |  |
+| Type 6  | Length 16 | CM message integrity check       |  |
+| Type 7  | Length 16 | CMTS message integrity check     |  |
+
+T0906540-98/d084
+
+**Figure B.6-26/J.112 – Example of Registration Request type value encodings**
+
+**B.6.3.2.7 Registration Response (REG-RSP)**
+
+A Registration Response, in the format shown in Figure B.6-27, MUST be transmitted by CMTS in response to received REG-REQ.
+
+![Diagram of Registration Response format showing MAC Management Message Header, SID from corresponding RNG-REQ, Response, and TLV encoded information with bit positions 0, 8, 16, 24, 31.](8f2d2d466bb3a096c1872fbc29ff4063_img.jpg)
+
+The diagram illustrates the structure of a Registration Response (REG-RSP) message. It is a 32-bit (4-byte) message. The first 16 bits (bits 0-15) are the MAC Management Message Header. The next 8 bits (bits 16-23) are the SID from the corresponding RNG-REQ. The following 8 bits (bits 24-31) are the Response. The final part of the message is TLV encoded information, which can vary in length and is shown as a dashed box extending downwards from bit 16.
+
+|                                |   |   |          |    |    |
+|--------------------------------|---|---|----------|----|----|
+| Bit                            | 0 | 8 | 16       | 24 | 31 |
+| MAC Management Message Header  |   |   |          |    |    |
+| SID from corresponding RNG-REQ |   |   | Response |    |    |
+| TLV encoded information        |   |   |          |    |    |
+
+Diagram of Registration Response format showing MAC Management Message Header, SID from corresponding RNG-REQ, Response, and TLV encoded information with bit positions 0, 8, 16, 24, 31.
+
+T0906550-98/d085
+
+**Figure B.6-27/J.112 – Registration Response format**
+
+To provide for flexibility, the message parameters following the SID MUST be encoded in a type/length/value form. Using this encoding, new parameters MAY be added which not all CMs can interpret. A CM which does not recognize a parameter type MUST skip over this parameter and MUST NOT treat the event as an error condition.
+
+Parameters MUST be as follows:
+
+|                                       |                                                                                                                                                                                                                                                                                      |
+|---------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| <b>SID from Corresponding REG-REQ</b> | SID from corresponding REG-REQ to which this response refers                                                                                                                                                                                                                         |
+| <b>Response</b>                       | 0 = ok<br>1 = authentication failure<br>2 = class of service failure                                                                                                                                                                                                                 |
+| <b>Modem Capabilities</b>             | The CMTS response to the capabilities of the modem                                                                                                                                                                                                                                   |
+| <b>Service Class Data</b>             | Returned when Response = ok<br>Service ID / service class tuple for each class of service granted                                                                                                                                                                                    |
+| <b>Service Not Available</b>          | Returned when Response = class of service failure.<br><br>If a service class cannot be supported, this configuration setting is returned in place of the service class data. If this is received, the entire registration request is considered to have failed and must be repeated. |
+| <b>Vendor-Specific Data</b>           | As defined in Appendix B.III: <ul style="list-style-type: none"><li>• Vendor ID Configuration Setting (vendor ID of CMTS)</li><li>• Vendor-specific extensions</li></ul>                                                                                                             |
+
+NOTE 1 – Service class IDs MUST be those requested in the corresponding REG-REQ.
+
+NOTE 2 – The initialization SID MUST no longer be used once the REG-RSP is received.
+
+#### **B.6.3.2.7.1 Encodings**
+
+The type values used MUST be those shown below. These are unique within the registration response message but not across the entire MAC message set. The type and length fields MUST each be 1 octet.
+
+##### **B.6.3.2.7.1.1 Modem capabilities**
+
+This field defines the CMTS response to the modem capability field in the Registration Request. The CMTS responds to the modem capabilities to indicate whether they may be used. If the CMTS does not recognize a modem capability, it must return this as "off" in the Registration Response.
+
+Only capabilities set to "on" in the REG-REQ may be set "on" in the REG-RSP as this is the handshake indicating that they have been successfully negotiated.
+
+Encodings are as defined for the Registration Request.
+
+##### **B.6.3.2.7.1.2 Service class data**
+
+This encoding defines the parameters associated with a requested class of service. It is somewhat complex in that it is composed from a number of encapsulated type/length/value fields. The encapsulated fields define the particular class of service parameters for the class of service in question. Note that the type fields defined are only valid within the encapsulated service class data configuration setting string. A single service class data configuration setting MUST be used to define the parameters for a single service class. Multiple class definitions MUST use multiple service class data configuration setting sets.
+
+| Type | Length | Value                      |
+|------|--------|----------------------------|
+| 1    | n      | Encoded service class data |
+
+**Internal service class data encodings**
+
+**Class ID**
+
+The value of the field MUST specify the identifier for the class of service to which the encapsulated string applies. This MUST be a class which was requested in the associated REG-REQ.
+
+| Type | Length | Value        |
+|------|--------|--------------|
+| 1    | 1      | from REG-REQ |
+
+**Valid Range**
+
+The class ID MUST be in the range 1 to 16.
+
+**Service ID**
+
+The value of the field MUST specify the SID associated with this service class.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 2    | 2      | SID   |
+
+**B.6.3.2.7.2 Registration Response encoding example**
+
+An example of Registration Response encoding is given in Figure B.6-28.
+
+|                                                                          |             |                                  |
+|--------------------------------------------------------------------------|-------------|----------------------------------|
+| Type<br>1                                                                | Length<br>7 | Service class definition class 1 |
+| Type<br>1                                                                | Length<br>7 | Service class definition class 2 |
+| <p>Image: Dashed box indicating additional service class definitions</p> |             |                                  |
+| Type<br>1                                                                | Length<br>7 | Service class definition class n |
+| Type<br>6                                                                | Length<br>6 | Modem capability                 |
+
+T0905880-97/d086
+
+**Figure B.6-28/J.112 – Example of Registration Response encoding**
+
+### B.6.3.2.7.3 Sample service class data encoding
+
+Sample service class data encodings are provided in Table B.6-18.
+
+**Table B.6-18/J.112 – Sample service class data encoding**
+
+| Type | Length | VALUE (sub)type | Length | Value    | Description                                                                       |
+|------|--------|-----------------|--------|----------|-----------------------------------------------------------------------------------|
+| 1    | 7      | 1<br>2          | 1<br>2 | 1<br>123 | Service class data configuration setting<br>Service class 1<br>SID for this class |
+| 1    | 7      | 1<br>2          | 1<br>2 | 2<br>244 | Service class data configuration setting<br>Service class 2<br>SID for this class |
+| 1    | 7      | 1<br>2          | 1<br>2 | n<br>345 | Service class data configuration setting<br>Service class n<br>SID for this class |
+
+### B.6.3.2.8 Upstream Channel Change Request (UCC-REQ)
+
+An Upstream Channel Change Request MAY be transmitted by a CMTS to cause a CM to change the upstream channel on which it is transmitting. The format of an UCC-REQ message is shown in Figure B.6-29.
+
+Parameters MUST be as follows:
+
+**Upstream channel ID** The identifier of the upstream channel to which the CM is to switch for upstream transmissions. This is an 8-bit field.
+
+![Diagram of Upstream Channel Change Request (UCC-REQ) message structure. It shows a 32-bit MAC Management Message Header (bits 0-31) followed by an 8-bit Upstream channel ID field (bits 0-7).](5ea288cb741dddda2a54203184649b5a_img.jpg)
+
+The diagram illustrates the structure of the UCC-REQ message. It consists of a 32-bit MAC Management Message Header (bits 0-31) and an 8-bit Upstream channel ID field (bits 0-7). The header is shown as a horizontal bar with brackets at the ends, and the Upstream channel ID is shown as a smaller box below it. The text 'T0906560-98/d087' is visible in the bottom right corner.
+
+Diagram of Upstream Channel Change Request (UCC-REQ) message structure. It shows a 32-bit MAC Management Message Header (bits 0-31) followed by an 8-bit Upstream channel ID field (bits 0-7).
+
+**Figure B.6-29/J.112 – Upstream Channel Change Request**
+
+### B.6.3.2.9 Upstream Channel Change Response (UCC-RSP)
+
+An Upstream Channel Change Response MUST be transmitted by a CM in response to a received Upstream Channel Change Request message to indicate that it has received and is complying with the UCC-REQ. The format of a UCC-RSP message is shown in Figure B.6-30.
+
+![Diagram of Upstream Channel Change Response (UCC-RSP) message structure. It shows a 32-bit MAC Management Message Header (bits 0-31) followed by an 8-bit Upstream channel ID field (bits 0-7).](88980d13d6e88a2e54ffdcdc02ba801c_img.jpg)
+
+The diagram illustrates the structure of the UCC-RSP message. It consists of a 32-bit MAC Management Message Header (bits 0-31) and an 8-bit Upstream channel ID field (bits 0-7). The header is shown as a horizontal bar with brackets at the ends, and the Upstream channel ID is shown as a smaller box below it. The text 'T0906570-98/d088' is visible in the bottom right corner.
+
+Diagram of Upstream Channel Change Response (UCC-RSP) message structure. It shows a 32-bit MAC Management Message Header (bits 0-31) followed by an 8-bit Upstream channel ID field (bits 0-7).
+
+**Figure B.6-30/J.112 – Upstream Channel Change Response**
+
+Before it begins to switch to a new upstream channel, a CM MUST transmit a UCC-RSP on its existing upstream channel. A CM MAY ignore an UCC-REQ message while it is in the process of performing a channel change. When a CM receives a UCC-REQ message requesting that it switch to an upstream channel that it is already using, the CM MUST respond with a UCC-RSP message on that channel indicating that it is already using the correct channel.
+
+To switch to a new upstream channel, a CM will begin a new ranging procedure for that channel, and upon completion of ranging will proceed without re-performing registration. The full procedure for changing channels is described in B.7.2.16.
+
+Parameters MUST be as follows:
+
+**Upstream channel ID** The identifier of the upstream channel to which the CM is to switch for upstream transmissions. This is the same Channel ID specified in the UCC-REQ message. This is an 8-bit field.
+
+#### B.6.4 Upstream bandwidth allocation
+
+The upstream channel is modelled as a stream of mini-slots. The CMTS MUST generate the time reference for identifying these slots. It MUST also control access to these slots by the cable modems. For example, it MAY grant some number of contiguous slots to a CM for it to transmit a data PDU. The CM MUST time its transmission so that the CMTS receives it in the time reference specified. This subclause describes the elements of protocol used in requesting, granting, and using upstream bandwidth. The basic mechanism for assigning bandwidth management is the allocation map. Please refer to Figure B.6-31.
+
+![Figure B.6-31/J.112 – Allocation map. The diagram illustrates the upstream channel structure and the allocation map. At the top, a 'Map PDU' is shown being transmitted on the downstream channel by the CMTS. Below this, a horizontal bar represents the 'Permitted use of the upstream channel', divided into segments representing mini-slots. An arrow labeled 'Mini-slots' points to the right. Below the mini-slots, a timeline shows the 'Previous map' and 'Current map'. The 'Current map' includes 'CM transmission opportunity', 'Request contention area', 'CM transmission opportunity', and 'Maintenance'. The 'As-yet unmapped time' is shown at the bottom right.](19a8fc45b10957bab04a686521657f46_img.jpg)
+
+The diagram illustrates the upstream channel structure and the allocation map. At the top, a "Map PDU" is shown being transmitted on the downstream channel by the CMTS. Below this, a horizontal bar represents the "Permitted use of the upstream channel", divided into segments representing mini-slots. An arrow labeled "Mini-slots" points to the right. Below the mini-slots, a timeline shows the "Previous map" and "Current map". The "Current map" includes "CM transmission opportunity", "Request contention area", "CM transmission opportunity", and "Maintenance". The "As-yet unmapped time" is shown at the bottom right.
+
+Figure B.6-31/J.112 – Allocation map. The diagram illustrates the upstream channel structure and the allocation map. At the top, a 'Map PDU' is shown being transmitted on the downstream channel by the CMTS. Below this, a horizontal bar represents the 'Permitted use of the upstream channel', divided into segments representing mini-slots. An arrow labeled 'Mini-slots' points to the right. Below the mini-slots, a timeline shows the 'Previous map' and 'Current map'. The 'Current map' includes 'CM transmission opportunity', 'Request contention area', 'CM transmission opportunity', and 'Maintenance'. The 'As-yet unmapped time' is shown at the bottom right.
+
+Figure B.6-31/J.112 – Allocation map
+
+The allocation map is a MAC Management message transmitted by the CMTS on the downstream channel which describes, for some interval, the uses to which the upstream mini-slots MUST be put. A given map MAY describe some slots as grants for particular stations to transmit data in, other slots as available for contention transmission, and other slots as an opportunity for new stations to join the link.
+
+Many different scheduling algorithms MAY be implemented in the CMTS by different vendors; this specification does not mandate a particular algorithm. Instead, it describes the protocol elements by which bandwidth is requested and granted.
+
+The bandwidth allocation MUST include the following basic elements:
+
+- Each CM has one or more short (14-bit) service identifiers as well as a 48-bit address.
+- Upstream bandwidth is divided into a stream of mini-slots. Each mini-slot is numbered relative to a master reference maintained by the CMTS. The clocking information is distributed to the CMs by means of SYNC packets.
+- CMs MAY issue requests to the CMTS for upstream bandwidth.
+
+The CMTS MUST transmit allocation map PDUs on the downstream channel defining the allowed usage of each mini-slot. The map is described below.
+
+#### **B.6.4.1 The Allocation Map MAC Management message**
+
+The allocation map is a varying-length MAC Management message that is transmitted by the CMTS to define transmission opportunities on the upstream channel. It includes a fixed-length header followed by a variable number of Information Elements (IEs) in the format shown in B.6.3.2.3. Each information element defines the allowed usage for a range of mini-slots.
+
+Note that it should be understood by both CM and CMTS that the lower (26-M) bits of alloc start and ack times MUST be used as the effective MAP start and ack times, where M is defined in B.6.3.2.2. The relationship between alloc start/ack time counters and the timestamp counter is further described in B.6.5.4.
+
+##### **B.6.4.1.1 Information elements**
+
+Each IE consists of a 14-bit Service ID, a 4-bit type code, and a 14-bit starting offset as defined in B.6.3.2.3. Since all stations MUST scan all IEs, it is critical that IEs be short and relatively fixed format. IEs within the map are strictly ordered by starting offset. For most purposes, the duration described by the IE is inferred by the difference between the IE's starting offset and that of the following IE. For this reason, a null IE MUST terminate the list. Refer to Table B.6-16.
+
+Four types of Service IDs are defined:
+
+- 1) 0x3FFF – Broadcast, intended for all stations.
+- 2) 0x2000-0x3FFE – Multicast, purpose is defined administratively. See Appendix B.I.
+- 3) 0x0001-0x1FFF – Unicast, intended for a particular CM or a particular service within that CM.
+- 4) 0x0000 – Null address, addressed to no station.
+
+The types of information elements which MUST be supported are defined below.
+
+###### **B.6.4.1.1.1 The Request IE**
+
+The Request IE provides an upstream interval in which requests MAY be made for bandwidth for upstream data transmission. The character of this IE changes depending on the class of Service ID. If broadcast, this is an invitation for CMs to contend for requests. Subclause B.6.4.4 describes which contention transmit opportunity may be used. If unicast, this is an invitation for a particular CM to request bandwidth. Unicasts MAY be used as part of a class-of-service implementation (see below). Packets transmitted in this interval MUST use the Request MAC Header format (see B.6.2.5.3).
+
+###### **B.6.4.1.1.2 The Request/Data IE**
+
+The Request/Data IE provides an upstream interval in which requests for bandwidth or short data packets MAY be transmitted. This IE is distinguished from the Request IE in that:
+
+- It provides a means by which allocation algorithms MAY provide for "immediate" data contention under light loads, and a means by which this opportunity can be withdrawn as network loading increases.
+
+- Multicast Service IDs MUST be used to specify maximum data length, as well as allowed random starting points within the interval. For example, a particular multicast ID MAY specify a maximum of 64-byte data packets, with random starting points of every fourth slot.
+
+A small number of well-known multicast Service IDs are defined in Appendix B.I. Others are available for vendor-specific algorithms.
+
+Since data packets transmitted within this interval may collide, the CMTS MUST acknowledge any that are successfully received. The data packet MUST indicate in the MAC Header that a data acknowledgment is desired (see Table B.6-12).
+
+#### **B.6.4.1.1.3 The Initial Maintenance IE**
+
+The Initial Maintenance IE provides an interval in which new stations may join the network. A long interval, equivalent to the maximum round-trip propagation delay plus the transmission time of the Ranging Request (RNG-REQ) message (see B.6.3.2.4), MUST be provided to allow new stations to perform initial ranging.
+
+Packets transmitted in this interval MUST use the RNG-REQ MAC Management message format (see B.6.3.2.4).
+
+#### **B.6.4.1.1.4 The Station Maintenance IE**
+
+The Station Maintenance IE provides an interval in which stations are expected to perform some aspect of routine network maintenance, such as ranging or power adjustment. The CMTS MAY request that a particular CM perform some task related to network maintenance, such as periodic transmit power adjustment. In this case, the Station Maintenance IE is unicast to provide upstream bandwidth in which to perform this task. Packets transmitted in this interval MUST use the RNG-REQ MAC Management message format (see B.6.3.2.4).
+
+#### **B.6.4.1.1.5 Short and Long Data Grant IEs**
+
+The Data Grant IE provides an opportunity for a CM to transmit one or more upstream PDUs. These IEs MAY also be used with an inferred length of zero mini-slots (a zero length grant), to indicate that a request has been received and is pending (a Data Grant Pending). This IE is issued either in response to a request from a station, or because of an administrative policy providing some amount of bandwidth to a particular station (see class-of-service discussion below).
+
+Short Data Grants are used with intervals less than or equal to the maximum burst size for this usage specified in the Upstream Channel Descriptor. If Short Data bursts are defined in the UCD, then all Long Data Grants MUST be for a larger number of mini-slots than the maximum for Short Data. The distinction between Long and Short Data Grants may be exploited in physical-layer forward-error-correction coding; otherwise, it is not meaningful to the bandwidth allocation process.
+
+If this IE is a Data Grant Pending (a zero length grant), it MUST follow all actual Data Grants (non-zero length grants). This allows cable modems to process all allocations first, before scanning the Map for request acknowledgements and data acknowledgements.
+
+#### **B.6.4.1.1.6 Data Acknowledge IE**
+
+The Data Acknowledge IE acknowledges that a data PDU was received. The CM MUST have requested this acknowledgment within the data PDU (normally this would be done for PDUs transmitted within a contention interval in order to detect collisions).
+
+This IE MUST follow all non-null-interval IEs. This allows cable modems to process all actual interval allocations first, before scanning the Map for request acknowledgements and data acknowledgements.
+
+#### **B.6.4.1.1.7 Expansion IE**
+
+The Expansion IE provides for extensibility, if more than 16-code points or 32 bits are needed for future IEs.
+
+#### **B.6.4.1.1.8 Null IE**
+
+A Null IE terminates all actual allocations in the IE list. It is used to infer a length for the last interval. All data acknowledgements and all null data grants follow the Null IE.
+
+#### **B.6.4.1.2 Requests**
+
+Only one type of upstream request is inherent to the allocation protocol: a request for upstream bandwidth. This request MAY be transmitted any time that either a request or a data PDU is allowed from the particular station. It MAY be transmitted during an interval described by any of:
+
+- a Request IE;
+- a Request/Data IE;
+- a Data Grant IE.
+
+In addition, it MAY be piggybacked<sup>5</sup> on a data transmission. The request includes:
+
+- the Service ID making the request;
+- the number of mini-slots or ATM cells requested.
+
+The number of mini-slots requested MUST be the total number that is desired by the CM at the time of the request (including any physical layer overhead)<sup>6</sup>, subject to administrative limits<sup>7</sup>. The CM MUST request a number of mini-slots corresponding to one or more complete packets. A non-concatenating CM MUST request only the necessary mini-slots for one MAC frame per request. If, for whatever reason, a previous request has not been satisfied when the CM is making a new request, it MUST include the number of slots from the old request in the new total. Note that only one request at a time (per Service ID) will be outstanding. Because the CMTS MUST continue to issue null grants for as long as a request is unsatisfied, the CM is able to unambiguously determine when its request is still pending.
+
+Administrative limits MAY be assigned, either globally or per Service ID, on the number of mini-slots that MAY be requested at once. The global limit is configured as the maximum transmission burst size.
+
+#### **B.6.4.2 Map Transmission and Timing**
+
+The allocation map MUST be transmitted in time to propagate across the physical cable and be received and handled by the receiving CMs. As such, it MAY be transmitted considerably earlier than its effective time. The components of the delay are:
+
+- Worst-case round-trip propagation delay – May be network-specific, but in the order of hundreds of microseconds.
+- Queuing delays within the CMTS – Implementation-specific.
+- Processing delays within the CMs – MUST allow a minimum processing time by each CM as specified in Appendix B.II (CM MAP Processing Time).
+- PMD-layer FEC interleaving.
+
+Within these constraints, vendors MAY wish to minimize this delay so as to minimize latency of access to the upstream channel.
+
+The number of mini-slots described MAY vary from map to map. At a minimum, a map MAY describe a single mini-slot. This would be wasteful in both downstream bandwidth and in processing time within the CMs. At a maximum, a map MAY stretch to tens of milliseconds. Such a map would provide poor upstream latency. Allocation algorithms MAY vary the size of the maps over time to provide a balance of network utilization and latency under varying traffic loads.
+
+---
+
+<sup>5</sup> When piggybacked, these values are carried in the Extended Header (Subclause 6.2.6, EH\_TYPE = 1).
+
+<sup>6</sup> Physical layer overhead that MUST be accounted for in a request includes: guard band, preamble, and FEC which are dependent on the burst profile.
+
+<sup>7</sup> The CM is limited by the Maximum Transmit Burst for the service class, as defined in Appendix B.III.
+
+At a minimum, a map MUST contain two Information Elements: one to describe an interval and a null IE to terminate the list. At a maximum, a map MUST be bounded by a limit of 240 information elements. Maps are also bounded in that they MUST NOT describe more than 4096 mini-slots into the future. The latter limit is intended to bound the number of future mini-slots that each CM is required to track. Even though several maps may be outstanding, the sum of the number of mini-slots they describe MUST NOT exceed 4096.
+
+The set of all maps, taken together, MUST describe every mini-slot in the upstream channel. If a CM fails to receive a map describing a particular interval, it MUST NOT transmit during that interval.
+
+Multiple maps MAY be outstanding at once.
+
+#### B.6.4.3 Protocol example
+
+This subclause illustrates the interchange between the CM and the CMTS when the CM has data to transmit (see Figure B.6-32). Suppose a given CM has a data PDU available for transmission.
+
+![Figure B.6-32/J.112 – Protocol example. A sequence diagram showing the interaction between a CMTS and a CM. The CMTS transmits a Map PDU at t1, which arrives at the CM at t2. The Map PDU has an effective starting time of t3 and contains a Request IE starting at t5. The CM transmits a Request at t4, which arrives at the CMTS at t6. The CMTS then transmits a second Map PDU at t7, which arrives at the CM at t8. This second map has an effective starting time of t9 and contains a data grant starting at t11. The CM then transmits its Data PDU at t10, which arrives at the CMTS at t11. Above the CMTS timeline, a shaded box labeled 'Slots mapped by first Map PDU' spans from t3 to t9. Another box labeled 'Second map' starts at t9. The diagram is labeled T0906580-98/d090.](e3026761f1da20ee91832039701984dd_img.jpg)
+
+Figure B.6-32/J.112 – Protocol example. A sequence diagram showing the interaction between a CMTS and a CM. The CMTS transmits a Map PDU at t1, which arrives at the CM at t2. The Map PDU has an effective starting time of t3 and contains a Request IE starting at t5. The CM transmits a Request at t4, which arrives at the CMTS at t6. The CMTS then transmits a second Map PDU at t7, which arrives at the CM at t8. This second map has an effective starting time of t9 and contains a data grant starting at t11. The CM then transmits its Data PDU at t10, which arrives at the CMTS at t11. Above the CMTS timeline, a shaded box labeled 'Slots mapped by first Map PDU' spans from t3 to t9. Another box labeled 'Second map' starts at t9. The diagram is labeled T0906580-98/d090.
+
+Figure B.6-32/J.112 – Protocol example
+
+#### Description
+
+- 1) At time  $t_1$ , the CMTS transmits a map whose effective starting time is  $t_3$ . Within this map is a Request IE which will start at  $t_5$ . The difference between  $t_1$  and  $t_3$  is needed to allow for:
+  - downstream propagation delay (including FEC interleaving) to allow all CMs to receive the Map;
+  - processing time at the CM (allows the CMs to parse the Map and translate it into transmission opportunities);
+  - upstream propagation delay (to allow the CM's transmission of the first upstream data to begin in time to arrive at the CMTS at time  $t_3$ ).
+- 2) At  $t_2$ , the CM receives this map and scans it for request opportunities. In order to minimize request collisions, it calculates  $t_6$  as a random offset based on the Data Back-off Start value in the most recent Map (see B.6.4.4, also the multicast SID definitions in B.I.2).
+- 3) At  $t_4$ , the CM transmits a request for as many mini-slots as needed to accommodate the PDU. Time  $t_4$  is chosen based on the ranging offset (see B.6.3.2.5) so that the request will arrive at the CMTS at  $t_6$ .
+- 4) At  $t_6$ , the CMTS receives the request and schedules it for service in the next map. (The choice of which requests to grant will vary with the class of service requested, any competing requests, and the algorithm used by the CMTS.)
+- 5) At  $t_7$ , the CMTS transmits a map whose effective starting time is  $t_9$ . Within this map, a data grant for the CM will start at  $t_{11}$ .
+- 6) At  $t_8$ , the CM receives the map and scans for its data grant.
+- 7) At  $t_{10}$ , the CM transmits its data PDU so that it will arrive at the CMTS at  $t_{11}$ . Time  $t_{10}$  is calculated from the ranging offset as in step 3).
+
+Steps 1) and 2) need not contribute to access latency if CMs routinely maintain a list of request opportunities.
+
+At step 3), the request may collide with requests from other CMs and be lost. The CMTS does not directly detect the collision. The CM determines that a collision (or other reception failure) occurred when the next map fails to include acknowledgment of the request. The CM MUST then perform a back-off algorithm and retry.
+
+At step 4), the CMTS scheduler MAY fail to accommodate the request within the next map. If so, it MUST reply with a zero-length grant in that map or discard the request by giving no grant at all. It MUST continue to report this zero-length grant in all succeeding maps until the request can be granted or is discarded. This MUST signal to the CM that the request is still pending. So long as the CM is receiving a zero-length grant, it MUST NOT issue new requests for that service queue.
+
+#### **B.6.4.4 Contention Resolution**
+
+The CMTS controls assignments on the upstream channel through the MAP and determines which mini-slots are subject to collisions. The CMTS MAY allow collisions on either Requests or Data PDUs.
+
+The mandatory method of contention resolution which MUST be supported is based on a truncated binary exponential back-off, with the initial back-off window and the maximum back-off window controlled by the CMTS. The values are specified as part of the Bandwidth Allocation Map (MAP) MAC message and represent a power-of-two value. For example, a value of 4 indicates a window between 0 and 15; a value of 10 indicates a window between 0 and 1023.
+
+When a CM has information to send and wants to enter the contention resolution process, it sets its internal back-off window equal to the Data Back-off Start defined in the MAP currently in effect.
+
+The CM MUST randomly select a number within its back-off window. This random value indicates the number of contention transmit opportunities which the CM MUST defer before transmitting. A CM MUST only consider contention transmit opportunities for which this transmission would have been eligible. These are defined by either Request IEs or Request/Data IEs in the MAP.
+
+NOTE 1 – Each IE can represent multiple transmission opportunities.
+
+As an example, consider a CM whose initial back-off window is 0 to 15 and it randomly selects the number 11. The CM must defer a total of 11 contention transmission opportunities. If the first available Request IE is for 6 requests, the CM does not use this and has 5 more opportunities to defer. If the next Request IE is for 2 requests, the CM has 3 more to defer. If the third Request IE is for 8 requests, the CM transmits on the fourth request, after deferring for 3 more opportunities.
+
+After a contention transmission, the CM waits for a Data Grant (Data Grant Pending) or Acknowledgment in a subsequent MAP. Once either is received, the contention resolution is complete. The CM determines that the contention transmission was lost when it finds a MAP without a Data Grant (Data Grant Pending) or Acknowledgment for it and with an Ack time more recent than the time of transmission. The CM MUST now increase its back-off window by a factor of two, as long as it is less than the maximum back-off window. The CM MUST randomly select a number within its new back-off window and repeat the deferring process described above.
+
+This retry process continues until the maximum number of retries (16) has been reached, at which time the PDU MUST be discarded.
+
+NOTE 2 – The maximum number of retries is independent of the initial and maximum back-off windows that are defined by the CMTS.
+
+If the CM receives a unicast Request or Data Grant at any time while deferring for this SID, it MUST stop the contention resolution process and use the explicit transmit opportunity.
+
+The CMTS has much flexibility in controlling the contention resolution. At one extreme, the CMTS MAY choose to set up the Data Back-off Start and End to emulate an Ethernet-style back-off with its associated simplicity and distributed nature, but also its fairness and efficiency issues. This would be done by setting initial = 0 and max = 10 in the MAP. At the other end, the CMTS MAY make the Data Back-off Start and End identical and frequently update these values in the MAP so all cable modems are using the same, and hopefully optimal, back-off window.
+
+A Transmit Opportunity is defined as any mini-slot in which a CM may be allowed to start a transmission. Transmit Opportunities typically apply to contention opportunities and are used to calculate the proper amount to defer in the contention resolution process.
+
+The number of Transmit Opportunities associated with a particular IE in a MAP is dependent on the total size of the region as well as the allowable size of an individual transmission. As an example, assume a REQ IE defines a region of 12 mini-slots. If the UCD defines a REQ that fits into a single mini-slot, then there are 12 Transmit Opportunities associated with this REQ IE, i.e. one for each mini-slot. If the UCD defines a REQ that fits in two mini-slots, then there are six Transmit Opportunities and a REQ can start on every other mini-slot.
+
+As another example, assume a REQ/Data IE that defines a 24 mini-slot region. If it is sent with an SID of 0x3FF4 (see Appendix B.I), then a CM can potentially start a transmit on every fourth mini-slot; so this IE contains a total of six Transmit Opportunities (TX OP). Similarly, a SID of 0x3FF6 implies four TX OPs; 0x3FF8 implies three TX OPs; and 0x3FFC implies two TX OPs.
+
+For an Initial Maintenance IE, a CM MUST start its transmission in the first mini-slot of the region; therefore it has a single Transmit Opportunity. The remainder of the region is used to compensate for the round-trip delays since the CM has not yet been ranged.
+
+Station Maintenance, Short and Long Data Grant IEs are specified for unicast and thus are NOT typically associated with contention Transmit Opportunities. They represent a single dedicated, or reservation-based, Transmit Opportunity.
+
+In summary (see Table B.6-19).
+
+**Table B.6-19/J.112 – Transmit Opportunity**
+
+| Interval            | SID type             | Transmit Opportunity                       |
+|---------------------|----------------------|--------------------------------------------|
+| Request             | Broadcast            | # mini-slots required for a Request        |
+| Request             | Multicast            | # mini-slots required for a Request        |
+| Request/Data        | Broadcast            | Not allowed                                |
+| Request/Data        | Well-known Multicast | As defined by SID in Appendix B.I          |
+| Request/Data        | Multicast            | Vendor specific algorithms                 |
+| Initial Maintenance | Broadcast            | Entire interval is a single tx opportunity |
+| Initial Maintenance | Multicast            | Entire interval is a single tx opportunity |
+
+#### B.6.4.5 CM Behaviour
+
+The following rules govern the response a CM may make when processing maps:
+
+- 1) A CM MUST first use any Grants assigned to it. Next, the CM MUST use any unicast REQ for it. Finally, the CM MUST use the next available broadcast/multicast REQ or REQ/Data IEs for which it is eligible.
+- 2) Only one Request may be outstanding at a time for a particular Service ID.
+- 3) If a CM has a Request pending, it MUST NOT use intervening contention intervals for that Service ID.
+
+#### B.6.4.6 Support for multiple channels
+
+Vendors MAY choose to offer various combinations of upstream and downstream channels within one MAC service access point. The upstream bandwidth allocation protocol allows for multiple upstream channels to be managed via one or many downstream channels.
+
+If multiple upstream channels are associated with a single downstream channel, then the CMTS MUST send one allocation map per upstream channel. The map's channel identifier, taken with the Upstream Channel Descriptor Message (see B.6.3.2.2), MUST specify to which channel each map applies. There is no requirement that the maps be synchronized across channels. Appendix B.VII provides an example.
+
+If multiple downstream channels are associated with a single upstream channel, the CMTS MUST ensure that the allocation map reaches all CMs. That is, if some CMs are attached to a particular downstream channel, then the map MUST be transmitted on that channel. This MAY necessitate that multiple copies of the same map be transmitted. The slot reference in the map header MUST always relate to the SYNC reference on the downstream channel on which it is transmitted.
+
+If multiple downstream channels are associated with multiple upstream channels, the CMTS MAY need to transmit multiple copies of multiple maps to ensure both that all upstream channels are mapped and that all CMs have received their needed maps.
+
+#### **B.6.4.7 Classes of service**
+
+This specification does not provide explicit classes of service, but provides the means for vendors to provide a variety of types of service.
+
+This subclause illustrates how the available mechanisms can be used to provide support for the service classes defined in [RFC-1633] "Integrated Services in the Internet Architecture: An Overview".
+
+[RFC-1633] divides applications into elastic applications which will always wait for data to arrive and inelastic applications in which the data must arrive within a certain time to be useful.
+
+Within the inelastic category, further subdivisions can be defined:
+
+- Delay-intolerant – The data must arrive within a perfectly reliable upper bound on delay.
+- Delay-tolerant – The data must arrive within a fairly reliable but not perfectly reliable delay bound.
+
+Within the elastic category the following application types can be distinguished:
+
+- interactive burst;
+- interactive bulk.
+
+The service model should be able to support both types of inelastic application and to allow for lower delays for interactive elastic applications than for bulk elastic applications.
+
+**Inelastic delay-intolerant** – The CMTS provides a Data Grant of fixed size to a configured Service ID once every N mini-slots. This Service ID MAY be assigned to all traffic for a CM, or it MAY only be used for this particular service within the CM.
+
+**Inelastic delay-tolerant** – The CMTS periodically provides a unicast Request IE to a configured Service ID. It then grants the request based on the negotiated delay variation, bandwidth, and other considerations. The CM has guaranteed access in which to make requests, and the CMTS's scheduling algorithm provides the negotiated service. As an alternative, the minimum data rate of the service negotiation MAY be provided in the same way that inelastic delay-intolerant traffic is handled.
+
+**Elastic application support** – Is provided by a contention/FIFO service strategy, in which CMs contend for request slots, and the CMTS services requests as they arrive. Service priorities can allow differential delays between interactive and bulk applications.
+
+##### **B.6.4.7.1 Resource-sharing**
+
+In order to support multiple end systems sharing the same upstream and downstream links, it is necessary to provide resource-sharing mechanisms for the link bandwidth. The following are some examples of this:
+
+**Link-usage feedback** is provided implicitly by contention and by the CMTS's scheduling algorithm, so no explicit congestion notifications are needed.
+
+**Guaranteed Minimum Bit Rate** can be provided in much the same manner as inelastic delay-tolerant application support.
+
+**Guaranteed Maximum Bit Rate** MAY be provided by a number of implementation mechanisms, including the CMTS's allocation algorithm and throttling within the CM.
+
+Service Priorities MUST be implemented by applying different service criteria to different Service IDs. It is anticipated that a particular CM MAY have several Service IDs, each corresponding to a particular service class. The particular services offered MAY vary from vendor to vendor.
+
+Contention that is limited to a service class MAY be accomplished with multicast Request IEs and Request/Data IEs. Creation of such multicast groups is vendor-specific.
+
+## **B.6.5 Timing and synchronization**
+
+One of the major challenges in designing a MAC protocol for a cable network is compensating for the large delays involved. These delays are an order of magnitude larger than the transmission burst time in the upstream. To compensate for these delays, the cable modem MUST be able to time its transmissions precisely to arrive at the CMTS at the start of the assigned mini-slot.
+
+To accomplish this, two pieces of information are needed by each cable modem:
+
+- a global timing reference sent downstream from the CMTS to all cable modems;
+- a timing offset, calculated during a ranging process, for each cable modem.
+
+### **B.6.5.1 Global timing reference**
+
+The CMTS MUST create a global timing reference by transmitting the Time Synchronization (SYNC) MAC management message downstream at a nominal frequency. The message contains a timestamp that exactly identifies when the CMTS transmitted the message. Cable modems MUST then compare the actual time the message was received with the timestamp and adjust their local clock references accordingly.
+
+The Transmission Convergence sublayer must operate closely with the MAC sublayer to provide an accurate timestamp for the SYNC message. As mentioned in the Ranging subclause below (see B.6.5.3), the model assumes that the timing delays through the remainder of the PHY layer MUST be relatively constant. Any variation in the PHY delays MUST be accounted for in the guard time of the PHY overhead.
+
+It is intended that the nominal interval between SYNC messages be tens of milliseconds. This imposes very little downstream overhead while letting cable modems acquire their global timing synchronization quickly.
+
+### **B.6.5.2 CM channel acquisition**
+
+Any cable modem MUST NOT use the upstream channel until it has successfully synchronized to the downstream.
+
+First, the cable modem MUST establish PMD sublayer synchronization. This implies that it has locked onto the correct frequency, equalized the downstream channel, recovered any PMD sublayer framing and the FEC is operational (refer to B.7.2.2). At this point, a valid bit stream is being sent to the transmission convergence sublayer. The transmission convergence sublayer performs its own synchronization (see B.5). On detecting the well-known MCNS PID, along with a payload unit start indicator per [ITU-T H.222.0], it delivers the MAC frame to the MAC sublayer.
+
+The MAC sublayer MUST now search for the Timing Synchronization (SYNC) MAC management messages. The cable modem achieves MAC synchronization once it has received at least two SYNC messages and has verified that its clock tolerances are within specified limits.
+
+A cable modem remains in "SYNC" as long as it continues to successfully receive the SYNC messages. If the Lost SYNC Interval (see Appendix B.II) has elapsed without a valid SYNC message, a cable modem MUST NOT use the upstream and MUST try to re-establish synchronization again.
+
+### B.6.5.3 Ranging
+
+Ranging is the process of acquiring the correct timing offset such that the cable modem's transmissions are aligned to the correct mini-slot boundary. The timing delays through the PHY layer MUST be relatively constant. Any variation in the PHY delays MUST be accounted for in the guard time of the upstream PMD overhead.
+
+First, a cable modem MUST synchronize to the downstream and learn the upstream channel characteristics through the Upstream Channel Descriptor MAC management message. At this point, the cable modem MUST scan the Bandwidth Allocation MAP message to find an Initial Maintenance Region . Refer to B.6.4.1.1.4. The CM must make an Initial Maintenance region large enough to account for the variation in delays between any two CMs.
+
+The cable modem MUST put together a Ranging Request message to be sent in an Initial Maintenance region. The SID field MUST be set to the non-initialized CM value (zero).
+
+Ranging adjusts each CM's timing offset such that it appears to be located right next to the CMTS. The CM MUST set its initial timing offset to the amount of internal fixed delay equivalent to putting this CM next to the CMTS. This amount includes delays introduced through a particular implementation, and MUST include the downstream PHY interleaving latency.
+
+When the Initial Maintenance transmit opportunity occurs, the cable modem MUST send the Ranging Request message. Thus, the cable modem sends the message as if it was physically right at the CMTS.
+
+Once the CMTS has successfully received the Ranging Request message, it MUST return a Ranging Response message addressed to the individual cable modem. Within the Ranging Response message MUST be a temporary SID assigned to this cable modem until it has completed the registration process. The message MUST also contain information on RF power level adjustment and offset frequency adjustment as well as any timing offset corrections.
+
+The cable modem MUST now wait for an individual Station Maintenance region assigned to its temporary SID. It MUST now transmit a Ranging Request message at this time using the temporary SID along with any power level and timing offset corrections.
+
+The CMTS MUST return another Ranging Response message to the cable modem with any additional fine tuning required. The ranging request/response steps MUST be repeated until the response contains a Ranging Successful notification. At this point, the cable modem MUST join normal data traffic in the upstream. See B.7 for complete details on the entire initialization sequence. In particular, state machines and the applicability of retry counts and timer values for the ranging process are defined in B.7.2.5.
+
+NOTE – The burst type to use for any transmission is defined by the Interval Usage Code (IUC). Each IUC is mapped to a burst type in the UCD message.
+
+### B.6.5.4 Timing units and relationships
+
+The SYNC message conveys a time reference that is measured in 6.25-ms ticks. Additional resolution of 6.25/64 ms is also present in the SYNC message to allow the CM to track the CMTS clock with a small phase offset. These units were chosen as the greatest-common-divisor of the upstream mini-slot time across various modulations and symbol rates. As this is decoupled from particular upstream channel characteristics, a single SYNC time reference may be used for all upstream channels associated with the downstream channel.
+
+The bandwidth allocation MAP uses time units of "mini-slots". A mini-slot represents the byte-time needed for transmission of a fixed number of bytes. The mini-slot is expected to represent 16 byte-times, although other values could be chosen. The size of the mini-slot, expressed as a multiple of the SYNC time reference, is carried in the Upstream Channel Descriptor. The example in Table B.6-20 relates mini-slots to the SYNC time ticks.
+
+The reader is encouraged to try other symbol rates and modulations. Note that the symbols/byte is a characteristic of an individual burst transmission, not of the channel. A mini-slot in this instance could represent either 16 or 32 bytes, depending on the modulation choice.
+
+A "mini-slot" is the unit of granularity for upstream transmission opportunities. There is no implication that any PDU can actually be transmitted in a single mini-slot.
+
+**Table B.6-20/J.112 – Example relating mini-slots to time ticks**
+
+| Parameter              | Example value                            |
+|------------------------|------------------------------------------|
+| Time tick              | 6.25 ms                                  |
+| Bytes per mini-slot    | 16 (nominal, when using QPSK modulation) |
+| Symbols/byte           | 4 (assuming QPSK)                        |
+| Symbols/s              | 2 560 000                                |
+| Mini-slots/s           | 40 000                                   |
+| Microseconds/mini-slot | 25                                       |
+| Ticks/mini-slot        | 4                                        |
+
+The MAP counts mini-slots in a 32-bit counter that normally counts to  $(2^{32} - 1)$  and then wraps back to zero. The least-significant bits (i.e. bit 0 to bit 25-M) of the mini-slot counter MUST match the most-significant bits (i.e. bit 6 + M to bit 31) of the SYNC timestamp counter. That is, mini-slot N begins at timestamp reference  $(N*T*64)$ , where  $T = 2^M$  is the UCD multiplier that defines the mini-slot (i.e. the number of time ticks per mini-slot).
+
+NOTE – The unused upper bits of the 32-bit mini-slot counter (i.e. bit 26-M to bit 31) are not needed by the CM and MAY be ignored.
+
+Note that the constraint that the UCD multiplier be a power of two has the consequence that the number of bytes per mini-slot must also be a power of two.
+
+## **B.6.6 Data link encryption support**
+
+The procedures to support data link encryption are defined in [MCNS2], [MCNS7] and [MCNS8]. The interaction between the MAC layer and the security system is limited to the items defined below.
+
+### **B.6.6.1 MAC messages**
+
+MAC Management messages (see B.6.3) MUST NOT be encrypted.
+
+### **B.6.6.2 Framing**
+
+The following rules MUST be followed when the encryption is applied to the frame:
+
+- Security specific header (Security Header of [MCNS2] or Privacy EH element of [MCNS8]) MUST be in the extended header and MUST be the first EH element of the Extended Header (EHDR) field.
+- Encrypted data is carried as Data PDU to the Cable MAC transparently.
+- When Security System Specification [MCNS2] is applied, Data PDU MUST be encrypted and decrypted using the mechanism defined in B.6.6.2.1.
+
+#### **B.6.6.2.1 Example of security system encryption**
+
+This example is defined for a frame received by a CM at the CMCI and transferred over the cable network to the CMTS and forwarded via an Ethernet-based NSI. For frames travelling in the NSI-to-CMCI direction, the roles of CM and CMTS are reversed.
+
+##### **B.6.6.2.1.1 CMCI to RF**
+
+Refer to Figure B.6-33.
+
+##### **B.6.6.2.1.2 RF to CMTS-NSI**
+
+Refer to Figure B.6-34.
+
+![Figure B.6-33/J.112 – Example of security framing at the CM. The diagram shows five steps of frame processing. Step 1: DA, SA, Type/Len, User Data, CRC. Step 2: DA, SA, Type/Len, User Data. Step 3: DA, SA, Type/Len, User Data (with 'Encrypted' arrow under User Data). Step 4: DA, SA, Type/Len, User Data, CRC (with 'Encrypted' arrow under User Data). Step 5: MAC Header, DA, SA, Type/Len, User Data, CRC (with 'Encrypted' arrow under User Data).](bdee2715697a4142d16a360549fa7c7f_img.jpg)
+
+Figure B.6-33/J.112 – Example of security framing at the CM. The diagram shows five steps of frame processing. Step 1: DA, SA, Type/Len, User Data, CRC. Step 2: DA, SA, Type/Len, User Data. Step 3: DA, SA, Type/Len, User Data (with 'Encrypted' arrow under User Data). Step 4: DA, SA, Type/Len, User Data, CRC (with 'Encrypted' arrow under User Data). Step 5: MAC Header, DA, SA, Type/Len, User Data, CRC (with 'Encrypted' arrow under User Data).
+
+T0906590-98/d091
+
+1. CM receives frame from Ethernet
+2. Check and discard Ethernet CRC
+3. Encrypt payload (DA, SA, Type/Len and User\_Data)
+4. Calculate new CRC over encrypted payload
+5. Add MAC\_Header including security header as the first EH element of the Extended Header (EHDR) field
+
+**Figure B.6-33/J.112 – Example of security framing at the CM**
+
+![Figure B.6-34/J.112 – Example of security framing at the CMTS. The diagram shows five steps of frame processing. Step 1: MAC Header, DA, SA, Type/Len, User Data, CRC (with 'Encrypted' arrow under User Data). Step 2: DA, SA, Type/Len, User Data, CRC (with 'Encrypted' arrow under User Data). Step 3: DA, SA, Type/Len, User Data (with 'Encrypted' arrow under User Data). Step 4: DA, SA, Type/Len, User Data. Step 5: DA, SA, Type/Len, User Data, CRC.](b18f943d96bfcb2b1360a27b9e45e11e_img.jpg)
+
+Figure B.6-34/J.112 – Example of security framing at the CMTS. The diagram shows five steps of frame processing. Step 1: MAC Header, DA, SA, Type/Len, User Data, CRC (with 'Encrypted' arrow under User Data). Step 2: DA, SA, Type/Len, User Data, CRC (with 'Encrypted' arrow under User Data). Step 3: DA, SA, Type/Len, User Data (with 'Encrypted' arrow under User Data). Step 4: DA, SA, Type/Len, User Data. Step 5: DA, SA, Type/Len, User Data, CRC.
+
+T0906600-98/d092
+
+1. Receive frame from RF interface
+2. Check and discard MAC Header including security header
+3. Check and discard CR
+4. Decrypt payload
+5. Recalculate CRC and forward frame to CMTS-NSI
+
+**Figure B.6-34/J.112 – Example of security framing at the CMTS**
+
+## B.7 Cable modem – CMTS interaction
+
+This subclause covers key requirements for interaction between the cable modem and CMTS. The interaction can be broken down into five basic categories: modem initialization, authentication, configuration, authorization, and signalling.
+
+### B.7.1 CMTS initialization
+
+The mechanism utilized for CMTS initialization (local terminal, file download, SNMP, etc.) is described in [MCNS5]. It MUST meet the following criteria for system interoperability:
+
+- The CMTS MUST be able to reboot and operate in a stand-alone mode using configuration data retained in non-volatile storage.
+
+- If valid parameters are not available from non-volatile storage or via another mechanism such as the Spectrum Management System (see [SMS]), the CMTS MUST not generate any downstream messages (including SYNC). This will prevent CMs from transmitting.
+- The CMTS MUST provide the information defined in B.6 to CMs for each upstream channel.
+
+### **B.7.2 Cable modem initialization**
+
+The procedure for initialization of a cable modem MUST be as shown in Figure B.7-1. This figure shows the overall flow between the stages of initialization in a CM. This shows no error paths, and is simply to provide an overview of the process. The more detailed finite state machine representations of the individual subclauses (including error paths) are shown in the subsequent figures. Timeout values are defined in Appendix B.II.
+
+The procedure can be divided into the following phases:
+
+- Removable Security Module (RSM) Detection.
+- Scan for downstream channel and establish synchronization with the CMTS.
+- Obtain transmit parameters (from UCD message).
+- Perform ranging.
+- Establish IP connectivity.
+- Establish time of day.
+- Establish Security Association (if RSM is present).
+- Transfer operational parameters.
+- Baseline Privacy initialization (if RSM is not present and CM is provisioned to run Baseline Privacy).
+
+Each CM contains the following information when shipped from the manufacturer:
+
+- A unique IEEE 802 48-bit MAC address which is assigned during the manufacturing process. This is used to identify the modem to the various provisioning servers during initialization.
+- Security information as defined in [MCNS2 and MCNS8] (e.g. X.509 certificate) used to authenticate the CM to the security server and authenticate the responses from the security and provisioning servers.
+
+The Specification and Description Language (SDL) notation used in the following figures is shown in Figure B.7-2 (refer to Recommendation Z.100 [ITU-T Z.100]).
+
+#### **B.7.2.1 RSM detection**
+
+When a CM is turned on, the CM determines whether Removable Security Module (RSM) is present in RSM slot or not as defined in [MCNS7].
+
+#### **B.7.2.2 Scanning and synchronization to downstream**
+
+On initialization or after signal loss, the cable modem MUST acquire a downstream channel. The CM MUST have non-volatile storage in which the last operational parameters are stored and MUST first try to re-acquire this downstream channel. If this fails, it MUST begin to continuously scan the 6-MHz channels of the downstream frequency band of operation until it finds a valid downstream signal.
+
+A downstream signal is considered to be valid when the modem has achieved the following steps:
+
+- synchronization of the QAM symbol timing;
+- synchronization of the FEC framing;
+- synchronization of the MPEG packetization;
+- recognition of SYNC downstream MAC messages.
+
+While scanning, it is desirable to give an indication to the user that the CM is doing so.
+
+![Flowchart of CM initialization overview showing steps for RSM Detection, Downstream Sync, Upstream Parameters, Ranging, IP Connectivity, Time of Day, RSM Present decision, Establish Security, Transfer Operational Parameters, Register with CMTS, 1a) decision, Baseline Privacy Initialization, and Operational state. Includes subclause references B.7.2.1 through B.7.2.11.](f5f5c0161d7d582a5a4c7227eb4e8eb0_img.jpg)
+
+```
+
+graph TD
+    subgraph LeftColumn [ ]
+        L1([RSM Detection]) --> L2{{RSM Detection Complete}}
+        L2 --> L3([Scan for Downstream Channel])
+        L3 --> L4{{Downstream Sync Established}}
+        L4 --> L5([Obtain Upstream Parameters])
+        L5 --> L6{{Upstream Parameters Acquired}}
+        L6 --> L7([Ranging and Automatic Adjustments])
+        L7 --> L8{{Ranging and Auto Adj Complete}}
+        L8 --> L9([Establish IP Connectivity])
+        L9 --> L10{{IP Complete}}
+        L10 --> L11([Establish Time of Day])
+        L11 --> L12{{Time of Day Established}}
+    end
+
+    L12 --> D1{RSM Present?}
+    D1 -- No --> D5
+    D1 -- Yes --> D2([Establish Security])
+    D2 --> D3{{Security Established}}
+    D3 --> D4([Transfer Operational Parameters])
+    D4 --> D5{{Transfer Complete}}
+    D5 --> D6([Register with CMTS])
+    D6 --> D7{{Registration Complete}}
+    D7 --> D8{1a)}
+    D8 -- No --> D11
+    D8 -- Yes --> D9([Baseline Privacy Initialization])
+    D9 --> D10{{Baseline Privacy Initialized}}
+    D10 --> D11([Operational])
+
+    style LeftColumn fill:none,stroke:none
+  
+```
+
+Subclause B.7.2.1
+
+Subclause B.7.2.2
+
+Subclause B.7.2.3
+
+Subclause B.7.2.5
+
+Subclause B.7.2.6
+
+Subclause B.7.2.7
+
+Subclause B.7.2.8
+
+Subclause B.7.2.9
+
+Subclause B.7.2.10
+
+Subclause B.7.2.11
+
+T0906400-98/d093
+
+Flowchart of CM initialization overview showing steps for RSM Detection, Downstream Sync, Upstream Parameters, Ranging, IP Connectivity, Time of Day, RSM Present decision, Establish Security, Transfer Operational Parameters, Register with CMTS, 1a) decision, Baseline Privacy Initialization, and Operational state. Includes subclause references B.7.2.1 through B.7.2.11.
+
+<sup>a)</sup> RSM not present and Baseline Privacy enabled.
+
+**Figure B.7-1/J.112 – CM initialization overview**
+
+![Figure B.7-2/J.112 – SDL notation diagram showing various symbol types: State symbol (oval), Input symbols (Internal and External, chevron shapes), Task symbol (rectangle), Output symbols (Internal and External, arrow shapes), and Decision symbol (diamond).](f97782852c7474fa58fcf5cd0bd96a7e_img.jpg)
+
+The diagram illustrates the SDL notation for various symbols used in state transition diagrams. It consists of the following elements:
+
+- State symbol:** Represented by a horizontal oval.
+- Input symbols:** Represented by two chevron shapes (pointing right). They are grouped by a brace and labeled "Internal" and "External".
+- Task symbol:** Represented by a horizontal rectangle.
+- Output symbols:** Represented by two arrow shapes (pointing right). They are grouped by a brace and labeled "Internal" and "External".
+- Decision symbol:** Represented by a diamond shape.
+
+T0905160-97/d094
+
+Figure B.7-2/J.112 – SDL notation diagram showing various symbol types: State symbol (oval), Input symbols (Internal and External, chevron shapes), Task symbol (rectangle), Output symbols (Internal and External, arrow shapes), and Decision symbol (diamond).
+
+**Figure B.7-2/J.112 – SDL notation**
+
+### B.7.2.3 Obtain upstream parameters
+
+Refer to Figure B.7-3 after synchronization, the CM MUST wait for an Upstream Channel Descriptor message (UCD) from the CMTS in order to retrieve transmission parameters for the upstream channel. These messages are transmitted periodically from the CMTS for all available upstream channels and are addressed to the MAC broadcast address. The CM MUST determine whether it can use the upstream channel from the channel description parameters. If the channel is not suitable, then the CM MUST wait for a Channel Description message for a channel which it can use. If no channel can be found after a suitable timeout period, then the CM MUST continue scanning to find another downstream channel.
+
+When the cable modem finds an upstream channel with acceptable transmission parameters, it MUST extract the parameters for this upstream from the UCD. It then MUST wait for the next SYNC message<sup>8</sup> and extract the upstream mini-slot timestamp from this message. The CM then MUST wait for a bandwidth allocation map for the selected channel. It MAY then begin transmitting upstream in accordance with the MAC operation and the bandwidth allocation mechanism.
+
+It is desirable to give an indication to the user that the CM has finished searching and has detected a valid downstream signal and upstream channel.
+
+<sup>8</sup> Alternatively, since the SYNC message applies to all upstream channels, the CM may have already acquired a time reference from previous SYNC messages. If so, it need not wait for a new SYNC.
+
+![Flowchart for obtaining upstream parameters. The process starts with 'Wait for usable UCD'. It then branches into two paths. The left path consists of 'Timeout T1' leading to 'Scanning'. The right path consists of 'Good upstream descriptor' leading to 'Wait for SYNC', then 'Sync', then 'Extract upstream mini-slot timing', then 'Wait for map for this channel', then 'Map for selected channel', and finally 'Ranging'. A small code 'T0905170-97/d095' is at the bottom right.](2fa686ed8033ac35efddee0c7be47d59_img.jpg)
+
+```
+
+graph TD
+    Start([Wait for usable UCD]) --> Branch(( ))
+    Branch --> T1[/Timeout T1/]
+    T1 --> Scanning([Scanning])
+    Branch --> Good[/Good upstream descriptor/]
+    Good --> WaitSYNC([Wait for SYNC])
+    WaitSYNC --> Sync[/Sync/]
+    Sync --> Extract[Extract upstream mini-slot timing]
+    Extract --> WaitMap([Wait for map for this channel])
+    WaitMap --> Map[/Map for selected channel/]
+    Map --> Ranging([Ranging])
+    T0905170-97/d095
+  
+```
+
+Flowchart for obtaining upstream parameters. The process starts with 'Wait for usable UCD'. It then branches into two paths. The left path consists of 'Timeout T1' leading to 'Scanning'. The right path consists of 'Good upstream descriptor' leading to 'Wait for SYNC', then 'Sync', then 'Extract upstream mini-slot timing', then 'Wait for map for this channel', then 'Map for selected channel', and finally 'Ranging'. A small code 'T0905170-97/d095' is at the bottom right.
+
+Figure B.7-3/J.112 – Obtaining upstream parameters
+
+#### B.7.2.4 Message flows during scanning and Upstream parameter acquisition
+
+The CMTS MUST generate SYNC and UCD messages on the downstream at periodic intervals within the ranges defined in B.6. These messages are addressed to all CMs. Refer to Figure B.7-4.
+
+#### B.7.2.5 Ranging and automatic adjustments
+
+The ranging and adjustment process is fully defined in B.6 and in the following subclauses. The message sequence chart and the finite state machines on the following pages define the ranging and adjustment process which MUST be followed by compliant CMs and CMTSs. Refer to Figures B.7-5 through B.7-8.
+
+NOTE – MAPs are transmitted as described in B.6.
+
+![Sequence diagram showing message flows between CMTS and CM during scanning and upstream parameter acquisition. The diagram shows a series of SYNC, UCD, and MAP messages from CMTS to CM, with corresponding CM responses and state changes.](88c92858439684b2103e88cb143fb98e_img.jpg)
+
+The diagram illustrates the message flows between a CMTS (Cable Modem Termination System) and a CM (Cable Modem) during scanning and upstream parameter acquisition. The sequence of events is as follows:
+
+- CMTS** sends a **SYNC** message at a specific clock time.
+- CM** receives the **SYNC** message.
+- CMTS** sends a **UCD** message at a specific clock time.
+- CM** receives the **UCD** message. This marks the start of an example UCD cycle prior to CM power-on.
+- CMTS** sends a **SYNC** message at a specific clock time.
+- CM** receives the **SYNC** message.
+- CMTS** sends a **SYNC** message at a specific clock time.
+- CM** receives the **SYNC** message.
+- CMTS** sends a **SYNC** message at a specific clock time.
+- CM** receives the **SYNC** message.
+- CMTS** sends a **SYNC** message at a specific clock time.
+- CM** receives the **SYNC** message.
+- CMTS** sends a **UCD** message at a specific clock time.
+- CM** receives the **UCD** message. This marks the completion of the power-on sequence.
+- CMTS** sends a **SYNC** message at a specific clock time.
+- CM** receives the **SYNC** message. The CM establishes PHY synchronization and waits for a UCD.
+- CMTS** sends a **SYNC** message at a specific clock time.
+- CM** receives the **SYNC** message.
+- CMTS** sends a **SYNC** message at a specific clock time.
+- CM** receives the **SYNC** message.
+- CMTS** sends a **UCD** message at a specific clock time.
+- CM** receives the **UCD** message. The CM obtains parameters for this upstream channel to use for initialization.
+- CMTS** sends a **SYNC** message at a specific clock time.
+- CM** receives the **SYNC** message. The CM extracts slot info for upstream and waits for a transmit opportunity to perform ranging.
+- CMTS** sends a **SYNC** message at a specific clock time.
+- CM** receives the **SYNC** message.
+- CMTS** sends a **MAP** message at a specific clock time.
+- CM** receives the **MAP** message. The CM starts the ranging process.
+
+Sequence diagram showing message flows between CMTS and CM during scanning and upstream parameter acquisition. The diagram shows a series of SYNC, UCD, and MAP messages from CMTS to CM, with corresponding CM responses and state changes.
+
+T0906750-98/d096
+
+Figure B.7-4/J.112 – Message flows during scanning and Upstream parameter acquisition
+
+![](5f7b02749ab85c5e65d6762767ab6d97_img.jpg)
+
+| CM <sub>TS</sub>                                                                                   |                   | CM                                                                        |
+|----------------------------------------------------------------------------------------------------|-------------------|---------------------------------------------------------------------------|
+| [time to send the Initial Maintenance opportunity]                                                 |                   |                                                                           |
+| Send map containing Initial Maintenance information element with a broadcast/multicast Service ID. | —————MAP—————→    |                                                                           |
+|                                                                                                    | ←————RNG-REQ————  | Transmit ranging packet in contention mode with Service ID parameter = 0. |
+| [receive recognizable ranging packet]                                                              |                   |                                                                           |
+| Allocate temporary Service ID.                                                                     |                   |                                                                           |
+| Send ranging response.                                                                             | —————RNG-RSP————→ |                                                                           |
+| Add temporary Service ID to poll list.                                                             |                   | Store temporary Service ID and adjust other parameters.                   |
+| [time to send the next map]                                                                        |                   |                                                                           |
+| Send map with Station Maintenance information element to modem using temporary SID.                | —————MAP—————→    | Recognize own temporary Service ID in map.                                |
+|                                                                                                    | ←————RNG-REQ————  | Reply to Station Maintenance opportunity poll.                            |
+| Send ranging response.                                                                             | —————RNG-RSP————→ | Adjust local parameters.                                                  |
+| [time to send an Initial Maintenance opportunity]                                                  |                   |                                                                           |
+| Send map containing Initial Maintenance information element with a broadcast/multicast Service ID. |                   |                                                                           |
+| Send periodic transmit opportunity to broadcast address.                                           | —————MAP—————→    |                                                                           |
+
+T0906760-98/d097
+
+NOTE – The CM<sub>TS</sub> MUST allow the CM sufficient time to have processed the previous RNG-RSP (i.e. to modify the transmitter parameters) before sending the CM a specific ranging opportunity. This is defined as CM Ranging Response Time in Appendix B.II.
+
+**Figure B.7-5/J.112 – Ranging and automatic adjustment procedure**
+
+![Flowchart for Initial Ranging - CM. The process starts with 'Wait for Initial Maintenance opportunity', leading to a split: 'Timeout T2' (Error Re-initialize MAC) and 'Map with maintenance opportunity' (Send RNG-REQ). 'Send RNG-REQ' leads to 'Wait for RNG-RSP', which then splits into 'Timeout T3' (Retries exhausted? Yes: Error Re-initialize MAC; No: Adjust local power, Random back-off (Note), Wait for Initial Maintenance opportunity) and 'RNG-RSP' (Adjust local parameters per RNG-RSP, Wait for Station Maintenance opportunity).](86c74ee06f834f849f6cd094ca0b5867_img.jpg)
+
+```
+
+graph TD
+    Start([Wait for Initial Maintenance opportunity])
+    T2{{Timeout T2}}
+    Error1([Error Re-initialize MAC])
+    Map{{Map with maintenance opportunity}}
+    SendRNG[/Send RNG-REQ/]
+    WaitRNG([Wait for RNG-RSP])
+    T3{{Timeout T3}}
+    Retries{Retries exhausted?}
+    Error2([Error Re-initialize MAC])
+    AdjustPower[Adjust local power]
+    Backoff[Random back-off  
+Note]
+    RNGRSP{{RNG-RSP}}
+    AdjustParams[Adjust local parameters per RNG-RSP]
+    WaitStation([Wait for Station Maintenance opportunity])
+
+    Start --- T2
+    Start --- Map
+    T2 --> Error1
+    Map --> SendRNG
+    SendRNG --> WaitRNG
+    WaitRNG --- T3
+    WaitRNG --- RNGRSP
+    T3 --> Retries
+    Retries -- Yes --> Error2
+    Retries -- No --> AdjustPower
+    AdjustPower --> Backoff
+    Backoff --> Start
+    RNGRSP --> AdjustParams
+    AdjustParams --> WaitStation
+  
+```
+
+T0906610-98/d098
+
+Flowchart for Initial Ranging - CM. The process starts with 'Wait for Initial Maintenance opportunity', leading to a split: 'Timeout T2' (Error Re-initialize MAC) and 'Map with maintenance opportunity' (Send RNG-REQ). 'Send RNG-REQ' leads to 'Wait for RNG-RSP', which then splits into 'Timeout T3' (Retries exhausted? Yes: Error Re-initialize MAC; No: Adjust local power, Random back-off (Note), Wait for Initial Maintenance opportunity) and 'RNG-RSP' (Adjust local parameters per RNG-RSP, Wait for Station Maintenance opportunity).
+
+NOTE – Timeout T3 may occur because the RNG-REQs from multiple modems collided. To avoid these modems repeating the loop in lockstep, a random back-off is required. This is a back-off over the ranging window specified in the MAP.
+
+**Figure B.7-6/J.112 – Initial Ranging – CM**
+
+![Flowchart for Initial Ranging - CM. The process starts with 'Wait for Station Maintenance opportunity'. It branches into 'Timeout T4' leading to 'Error: Re-initialize MAC' and 'Map with Maintenance opportunity' leading to 'Send RNG-REQ'. 'Send RNG-REQ' leads to 'Wait for RNG-RSP', which then branches into 'Timeout T3' leading to a 'Retries exhausted?' decision and 'RNG-RSP' leading to 'Adjust local parameters per RNG-RSP'. 'Retries exhausted?' leads to 'Error: Re-initialize MAC' (Yes) or 'Adjust local power' (No). 'Adjust local power' leads to 'Wait for Station Maintenance opportunity'. 'Adjust local parameters per RNG-RSP' leads to 'Success set from CMTS? (Note)'. 'Success set from CMTS?' leads to 'Enable data transfer' (Yes) or 'Abort ranging set from CMTS?' (No). 'Abort ranging set from CMTS?' leads to 'Error: Re-initialize MAC' (Yes) or 'Adjust local power' (No). 'Enable data transfer' leads to 'Establish IP layer'. A note at the bottom right reads 'T0906620-98/d099'.](f2a3faa7fc860dd26eda5b88460b0bcf_img.jpg)
+
+```
+
+graph TD
+    Start([Wait for Station Maintenance opportunity]) --> T4{Timeout T4}
+    Start --> Map[Map with Maintenance opportunity]
+    T4 --> Error1([Error: Re-initialize MAC])
+    Map --> SendRNG[Send RNG-REQ]
+    SendRNG --> WaitRNG([Wait for RNG-RSP])
+    WaitRNG --> T3{Timeout T3}
+    WaitRNG --> RNGRSP[RNG-RSP]
+    T3 --> Retries{Retries exhausted?}
+    Retries -- Yes --> Error2([Error: Re-initialize MAC])
+    Retries -- No --> AdjustPower[Adjust local power]
+    AdjustPower --> Start
+    RNGRSP --> AdjustParams[Adjust local parameters per RNG-RSP]
+    AdjustParams --> Success{Success set from CMTS? (Note)}
+    Success -- Yes --> EnableData[Enable data transfer]
+    Success -- No --> Abort{Abort ranging set from CMTS?}
+    Abort -- Yes --> Error3([Error: Re-initialize MAC])
+    Abort -- No --> AdjustPower
+    EnableData --> EstablishIP([Establish IP layer])
+  
+```
+
+T0906620-98/d099
+
+Flowchart for Initial Ranging - CM. The process starts with 'Wait for Station Maintenance opportunity'. It branches into 'Timeout T4' leading to 'Error: Re-initialize MAC' and 'Map with Maintenance opportunity' leading to 'Send RNG-REQ'. 'Send RNG-REQ' leads to 'Wait for RNG-RSP', which then branches into 'Timeout T3' leading to a 'Retries exhausted?' decision and 'RNG-RSP' leading to 'Adjust local parameters per RNG-RSP'. 'Retries exhausted?' leads to 'Error: Re-initialize MAC' (Yes) or 'Adjust local power' (No). 'Adjust local power' leads to 'Wait for Station Maintenance opportunity'. 'Adjust local parameters per RNG-RSP' leads to 'Success set from CMTS? (Note)'. 'Success set from CMTS?' leads to 'Enable data transfer' (Yes) or 'Abort ranging set from CMTS?' (No). 'Abort ranging set from CMTS?' leads to 'Error: Re-initialize MAC' (Yes) or 'Adjust local power' (No). 'Enable data transfer' leads to 'Establish IP layer'. A note at the bottom right reads 'T0906620-98/d099'.
+
+NOTE – Ranging Request is within the tolerance of the CMTS.
+
+**Figure B.7-7/J.112 – Initial Ranging – CM**
+
+![Flowchart for Initial Ranging - CM/CS. The process starts with 'Wait for recognizable RNG-REQ', followed by 'RNG-REQ'. A decision 'SID assigned to this CM already?' leads to either 'Reset retry count in poll list for this CM' or 'Assign temporary SID' followed by 'Add CM to poll list for future maps'. Both lead to 'Send RNG-RSP'. A note indicates 'Map will be sent per allocation algorithm and pending till complete (Note 2)'. The next step is 'Wait for polled RNG-REQ'. From here, if 'RNG-REQ not received', a decision 'Retries exhausted?' follows. If 'Yes', 'Remove CM from poll list' and 'Wait for recognizable RNG-REQ' occur. If 'No', the flow returns to 'Send RNG-RSP'. If 'RNG-REQ' is received, a decision 'Good enough? (Note 1)' follows. If 'Yes', 'Send RNG-RSP (success)' and 'Remove CM from poll list' lead to 'Done'. If 'No', a decision 'Retries exhausted?' follows. If 'Yes', 'Send RNG-RSP (abort)' and 'Wait for recognizable RNG-REQ' occur. If 'No', 'Send RNG-RSP (continue)' and 'Wait for polled RNG-REQ' occur. The diagram is labeled T0906740-98/d100.](cf8d9315f7f99ef87b4040c7312c5c6f_img.jpg)
+
+```
+
+graph TD
+    Start([Wait for recognizable RNG-REQ]) --> RNG_REQ[/RNG-REQ/]
+    RNG_REQ --> SID_Assigned{SID assigned to this CM already?}
+    SID_Assigned -- Yes --> Reset_Retry[Reset retry count in poll list for this CM]
+    SID_Assigned -- No --> Assign_SID[Assign temporary SID]
+    Assign_SID --> Add_Poll[Add CM to poll list for future maps]
+    Reset_Retry --> Send_RNG_RSP[/Send RNG-RSP/]
+    Add_Poll --> Send_RNG_RSP
+    Send_RNG_RSP --> Wait_Polled_RNG_REQ([Wait for polled RNG-REQ])
+    Note2[Map will be sent per allocation algorithm and pending till complete (Note 2)] -.-> Send_RNG_RSP
+    Wait_Polled_RNG_REQ --> RNG_Req_Received[/RNG-REQ/]
+    Wait_Polled_RNG_REQ --> RNG_Req_Not_Received[/RNG-REQ not received/]
+    RNG_Req_Not_Received --> Retries_Exhausted_1{Retries exhausted?}
+    Retries_Exhausted_1 -- Yes --> Remove_Poll_1[Remove CM from poll list]
+    Remove_Poll_1 --> Start
+    Retries_Exhausted_1 -- No --> Send_RNG_RSP
+    RNG_Req_Received --> Good_Enough{Good enough? (Note 1)}
+    Good_Enough -- Yes --> Send_RNG_RSP_Success[/Send RNG-RSP (success)/]
+    Send_RNG_RSP_Success --> Remove_Poll_2[Remove CM from poll list]
+    Remove_Poll_2 --> Done([Done])
+    Good_Enough -- No --> Retries_Exhausted_2{Retries exhausted?}
+    Retries_Exhausted_2 -- Yes --> Send_RNG_RSP_Abort[/Send RNG-RSP (abort)/]
+    Send_RNG_RSP_Abort --> Start
+    Retries_Exhausted_2 -- No --> Send_RNG_RSP_Continue[/Send RNG-RSP (continue)/]
+    Send_RNG_RSP_Continue --> Wait_Polled_RNG_REQ
+  
+```
+
+Flowchart for Initial Ranging - CM/CS. The process starts with 'Wait for recognizable RNG-REQ', followed by 'RNG-REQ'. A decision 'SID assigned to this CM already?' leads to either 'Reset retry count in poll list for this CM' or 'Assign temporary SID' followed by 'Add CM to poll list for future maps'. Both lead to 'Send RNG-RSP'. A note indicates 'Map will be sent per allocation algorithm and pending till complete (Note 2)'. The next step is 'Wait for polled RNG-REQ'. From here, if 'RNG-REQ not received', a decision 'Retries exhausted?' follows. If 'Yes', 'Remove CM from poll list' and 'Wait for recognizable RNG-REQ' occur. If 'No', the flow returns to 'Send RNG-RSP'. If 'RNG-REQ' is received, a decision 'Good enough? (Note 1)' follows. If 'Yes', 'Send RNG-RSP (success)' and 'Remove CM from poll list' lead to 'Done'. If 'No', a decision 'Retries exhausted?' follows. If 'Yes', 'Send RNG-RSP (abort)' and 'Wait for recognizable RNG-REQ' occur. If 'No', 'Send RNG-RSP (continue)' and 'Wait for polled RNG-REQ' occur. The diagram is labeled T0906740-98/d100.
+
+NOTE 1 – Means ranging is within the tolerable limits of the CM/CS.
+
+NOTE 2 – RNG-REQ pending-till-complete was non-zero, the CM/CS SHOULD hold off the station maintenance opportunity accordingly, unless needed, for example, to adjust the CM's power level. If opportunities are offered prior to the pending-till-complete expiry, the "good-enough" test which follows receipt of a RNG-RSP MUST NOT judge the CM's transmit equalization until pending-till-complete expires.
+
+Figure B.7-8/J.112 – Initial Ranging – CM/CS
+
+### B.7.2.5.1 Ranging parameter adjustment
+
+Adjustment of local parameters (e.g. transmit power) in a CM as a result of the receipt (or non-receipt) of an RNG-RSP is considered to be implementation-dependent with the following restrictions (refer to B.6.2.7):
+
+- All parameters MUST be within the approved range at all times.
+- Power adjustment MUST start from the minimum value unless a valid power is available from non-volatile storage, in which case this MUST be used as a starting point.
+- Power adjustment MUST be capable of being reduced or increased by the specified amount in response to RNG-RSP messages.
+- If power is adjusted to the maximum value, it MUST wrap back to the minimum.
+
+### B.7.2.5.2 Periodic ranging
+
+The CMTS MUST provide each CM a Periodic Ranging opportunity at least once every T4 s. The CMTS MUST send out Periodic Ranging opportunities at an interval sufficiently shorter than T4 that a MAP could be missed without the CM timing out. The size of this "subinterval" is CMTS dependent.
+
+The CM MUST reinitialize its MAC layer after T4 s have elapsed without receiving a Periodic Ranging opportunity.
+
+### B.7.2.6 Establish IP connectivity
+
+At this point, the CM MUST invoke DHCP mechanisms [RFC-1541] in order to obtain an IP address and any other parameters needed to establish IP connectivity (see Appendix B.III). The DHCP response MUST contain the name of a file which contains further configuration parameters. Refer to Figure B.7-9.
+
+![Sequence diagram showing the DHCP process between a CM and a DHCP server. The CM sends a DHCP discover to the broadcast address. The DHCP server checks the CM MAC address and responds with a DHCP offer. The CM chooses a server and sends a DHCP request. The DHCP server processes the request and sends a DHCP response. Finally, the CM sets up IP parameters from the DHCP response.](e7e5bf8091872a80c572fe532b5d7010_img.jpg)
+
+```
+sequenceDiagram
+    participant CM
+    participant DHCP
+    Note left of CM: Send DHCP request to broadcast address.
+    CM->>DHCP: DHCP discover
+    Note right of DHCP: Check CM MAC address and respond.
+    DHCP-->>CM: DHCP offer
+    Note left of CM: Choose server.
+    CM->>DHCP: DHCP request
+    Note right of DHCP: Process request.
+    DHCP-->>CM: DHCP response
+    Note left of CM: Set up IP parameters from DHCP response.
+```
+
+Sequence diagram showing the DHCP process between a CM and a DHCP server. The CM sends a DHCP discover to the broadcast address. The DHCP server checks the CM MAC address and responds with a DHCP offer. The CM chooses a server and sends a DHCP request. The DHCP server processes the request and sends a DHCP response. Finally, the CM sets up IP parameters from the DHCP response.
+
+T0906630-98/d101
+
+Figure B.7-9/J.112 – Establishing IP connectivity
+
+### B.7.2.7 Establish time of day
+
+The CM and CMTS need to have the current date and time. This need not be authenticated and need only be accurate to the nearest second [MCNS2].
+
+This is required for:
+
+- time-stamping logged events which can be retrieved by the management system;
+- key management by the security system.
+
+The protocol by which the time of day is retrieved will be as defined in [RFC-868]. Refer to Figure B.7-10.
+
+The request and response will be transferred using UDP.
+
+The time retrieved from the server (UTC) will be combined with the time offset received from the DHCP response to create the current local time.
+
+![Sequence diagram showing the interaction between a CM and a Time Server to establish the time of day. The CM sends a 'time of day request' to the Time Server. The Time Server processes the request and sends a 'time of day response' back to the CM. The CM then sets up the correct time of day from the response.](c8363610940980ea7cd1611443c94ef5_img.jpg)
+
+```
+
+sequenceDiagram
+    participant CM
+    participant Time Server
+    Note left of CM: Send request to time server.
+    CM->>Time Server: time of day request
+    Note right of Time Server: Process request
+    Time Server-->>CM: time of day response
+    Note left of CM: Set up/correct time of day from response.
+  
+```
+
+Sequence diagram showing the interaction between a CM and a Time Server to establish the time of day. The CM sends a 'time of day request' to the Time Server. The Time Server processes the request and sends a 'time of day response' back to the CM. The CM then sets up the correct time of day from the response.
+
+T0906640-98/d102
+
+**Figure B.7-10/J.112 – Establishing time of day**
+
+### B.7.2.8 Establish security association
+
+If the RSM module is detected and no security association has been established, the CM MUST establish a security association at this point. The IP address of the security server (or servers) MUST be provided as part of the DHCP response. The procedures required are fully defined in [MCNS2].
+
+### B.7.2.9 Transfer operational parameters
+
+After the DHCP and security association operations are successful, the modem MUST download the parameter file using TFTP, as shown in Figure B.7-11. The TFTP configuration parameter server is specified by the "siaddr" field of the DHCP response.
+
+The parameter fields required in the DHCP response and the format and content of the configuration file MUST be as defined in Appendix B.III. Note that these fields are the minimum required for interoperability.
+
+![Sequence diagram showing the interaction between a CM, CMTS, and TFTP Server to transfer operational parameters and registration. The CM sends a 'Request parameter file.' to the TFTP Server. The TFTP Server processes the request and sends a '-TFTP REQ-' to the CMTS. The CMTS then sends a '-TFTP RSP-' back to the CM. The CM sets up operational parameters. The CM then sends a 'REG- REQ' to the CMTS. The CMTS provisions the modem and sends a 'REG- RSP' back to the CM. The CM sets up Service IDs.](20e325591c62b3aed441a45d3fbaff67_img.jpg)
+
+```
+
+sequenceDiagram
+    participant CM
+    participant CMTS
+    participant TFTP as TFTP Server
+    Note left of CM: Request parameter file.
+    CM->>TFTP: 
+    Note right of TFTP: Server  
+Process request
+    TFTP->>CMTS: —TFTP REQ—
+    CMTS->>CM: —TFTP RSP—
+    Note left of CM: Set up operational parameters.
+    Note left of CM: Inform CMTS.
+    CM->>CMTS: —REG- REQ—
+    Note right of CMTS: Provision modem
+    CMTS->>CM: —REG- RSP—
+    Note left of CM: Set up Service IDs.
+  
+```
+
+Sequence diagram showing the interaction between a CM, CMTS, and TFTP Server to transfer operational parameters and registration. The CM sends a 'Request parameter file.' to the TFTP Server. The TFTP Server processes the request and sends a '-TFTP REQ-' to the CMTS. The CMTS then sends a '-TFTP RSP-' back to the CM. The CM sets up operational parameters. The CM then sends a 'REG- REQ' to the CMTS. The CMTS provisions the modem and sends a 'REG- RSP' back to the CM. The CM sets up Service IDs.
+
+T0906650-98/d103
+
+**Figure B.7-11/J.112 – Transferring operational parameters and registration**
+
+### B.7.2.10 Registration
+
+A CM MUST be authorized to forward traffic into the network once it is initialized, authenticated and configured. Refer to Figure B.7-11.
+
+The configuration parameters downloaded to the CM MUST include a network access control object (see Appendix B.III.8.5). If this is set to "no forwarding", the CM MUST not forward data to the network. It MUST respond to network management requests. This allows the CM to be configured in a mode in which it is manageable but will not forward data.
+
+The CM MUST forward the operational parameters to the CMTS as part of a registration request. The CMTS MUST perform the following operations to confirm the CM authorization:
+
+- check the MAC and the authentication signature on the parameter list;
+- build a profile for the modem based on the standard configuration settings (see Appendix B.III);
+- assign a Service ID based on the classes of service supported;
+- reply to the modem registration request.
+
+Vendor-specific configuration settings MUST be ignored (except for inclusion in message authorization code calculation).
+
+#### **B.7.2.11 Baseline Privacy initialization**
+
+Following registration, if the RSM module is NOT detected and the CM is provisioned to run Baseline Privacy, the CM MUST initialize Baseline Privacy operations, as described in [MCNS8]. A CM is provisioned to run Baseline Privacy if its configuration file includes a Baseline Privacy Configuration Setting.
+
+#### **B.7.2.12 Service IDs during CM initialization**
+
+After completion of the Registration process (see B.7.2.10), the CM will have been assigned Service IDs (SIDs) to match its class of service provisioning. However, the CM must complete a number of protocol transactions prior to that time (e.g. Ranging, DHCP, etc.), and requires a temporary Service ID in order to complete those steps.
+
+On reception of an Initial Ranging Request, the CMTS MUST allocate a temporary SID and assign it to the CM for initialization use. The CMTS MAY monitor use of this SID and restrict traffic to that needed for initialization. It MUST inform the CM of this assignment in the Ranging Response.
+
+On receiving a Ranging Response addressed to it, the CM MUST use the assigned temporary SID for further initialization transmission requests until the Registration Response is received.
+
+On receiving a Ranging Response instruction to move to a new downstream frequency and/or upstream channel ID, the CM MUST consider any previously assigned temporary SID to be deassigned, and must obtain a new temporary SID via initial ranging.
+
+It is possible that the Ranging Response may be lost after transmission by the CMTS. The CM MUST recover by timing out and re-issuing its Initial Ranging Request. Since the CM is uniquely identified by the source MAC address in the Ranging Request, the CMTS MAY immediately re-use the temporary SID previously assigned. If the CMTS assigns a new temporary SID, it MUST make some provision for aging out the old SID that went unused (see B.6.3.2.7).
+
+When assigning class-of-service-provisioned SIDs on receiving a Registration Request, the CMTS may re-use the temporary SID, assigning it to one of the class of service classes requested. If so, it MUST continue to allow initialization messages on that SID, since the Registration Response could be lost in transit. If the CMTS assigns all-new SIDs for class-of-service provisioning, it MUST age out the temporary SID. The aging-out MUST allow sufficient time to complete the registration process in case the Registration Response is lost in transit.
+
+#### **B.7.2.13 Multiple-channel support**
+
+In the event that more than one downstream signal is present in the system, the CM MUST operate using the first valid downstream signal that it encounters when scanning. It will be instructed via the parameters in the configuration file (see Appendix B.III) to shift operation to different downstream and/or upstream frequencies if necessary.
+
+Both upstream and downstream channels MUST be identified where required in MAC management messages using channel identifiers.
+
+#### B.7.2.14 Remote RF signal level adjustment
+
+RF signal level adjustment at the CM is performed through a periodic maintenance function using the RNG-REQ and RNG-RSP MAC messages. This is similar to initial ranging and is shown in Figures B.7-12 and B.7-13. On receiving a RNG-RSP, the CM MUST NOT transmit until the RF signal has been adjusted in accordance with the RNG-RSP and has stabilized (refer to B.4).
+
+![Flowchart for Periodic Ranging - CMTS. The process starts with adding a CM to a poll list on a periodic timer. It then enters a loop waiting for a polled RNG-REQ. If not received, it checks if retries are exhausted. If yes, it aborts, removes the CM from the poll list, destroys SIDs, and ends. If no, it continues. If received, it checks if the signal is 'Good enough?'. If yes, it sends a success RNG-RSP, removes the CM from the poll list, and ends. If no, it checks if retries are exhausted. If yes, it aborts. If no, it sends a continue RNG-RSP and loops back to waiting for a polled RNG-REQ.](d33f50868e9cfda1b1206833c4061e12_img.jpg)
+
+```
+
+graph TD
+    Start[On periodic timer  
+add CM to poll list  
+for future maps] --> WaitRNG([Wait for polled  
+RNG-REQ])
+    MapNote[Map will be sent per  
+allocation algorithm] -.-> WaitRNG
+    WaitRNG --> NotRec[/RNG-REQ not  
+received/]
+    WaitRNG --> Rec[/RNG-REQ/]
+    NotRec --> Retries1{Retries  
+exhausted?}
+    Retries1 -- No --> WaitRNG
+    Retries1 -- Yes --> Abort[Send  
+RNG-RSP  
+(abort)]
+    Rec --> Good{Good  
+enough?  
+(Note)}
+    Good -- Yes --> Success[Send  
+RNG-RSP  
+(success)]
+    Good -- No --> Retries2{Retries  
+exhausted?}
+    Retries2 -- Yes --> Abort
+    Retries2 -- No --> Continue[Send  
+RNG-RSP  
+(continue)]
+    Continue --> WaitRNG
+    Abort --> RemovePoll[Remove CM from  
+poll list]
+    Success --> RemovePoll2[Remove CM from  
+poll list]
+    RemovePoll --> Destroy[Destroy SIDs  
+associated with  
+this CM]
+    Destroy --> Done1([Done])
+    RemovePoll2 --> Done2([Done])
+    style NotRec fill:none,stroke-width:1px
+    style Rec fill:none,stroke-width:1px
+    subgraph ID [T0905210-97/d104]
+    end
+
+```
+
+Flowchart for Periodic Ranging - CMTS. The process starts with adding a CM to a poll list on a periodic timer. It then enters a loop waiting for a polled RNG-REQ. If not received, it checks if retries are exhausted. If yes, it aborts, removes the CM from the poll list, destroys SIDs, and ends. If no, it continues. If received, it checks if the signal is 'Good enough?'. If yes, it sends a success RNG-RSP, removes the CM from the poll list, and ends. If no, it checks if retries are exhausted. If yes, it aborts. If no, it sends a continue RNG-RSP and loops back to waiting for a polled RNG-REQ.
+
+NOTE – Means Ranging Request is within the tolerance limits of the CMTS for power and transmit equalization (if supported).
+
+**Figure B.7-12/J.112 – Periodic Ranging – CMTS**
+
+![Flowchart for Periodic Ranging - CM View. The process starts at 'Operational', leading to a 'Wait for Station Maintenance opportunity' state. From there, it branches into 'Station Maintenance opportunity' (leading to 'Send RNG-REQ') and 'Timeout T4' (leading to 'Error: Re-initialize MAC'). 'Send RNG-REQ' leads to 'RNG-RSP', which then leads to a decision 'Abort ranging from CMTS?'. If 'Yes', it leads to 'Error: Re-initialize MAC'. If 'No', it leads to 'Adjust local parameters per RNG-RSP', which then loops back to 'Operational'. A small code 'T0906660-98/d105' is at the bottom right.](4851479cde0f63d07f4db536c69bbdef_img.jpg)
+
+```
+
+graph TD
+    Operational([Operational]) --> Wait[Wait for Station Maintenance opportunity]
+    Wait --> SM[Station Maintenance opportunity]
+    Wait --> T4[Timeout T4]
+    SM --> SendRNG[Send RNG-REQ]
+    SendRNG --> RNGRSP[RNG-RSP]
+    T4 --> Error[Error: Re-initialize MAC]
+    RNGRSP --> Abort{Abort ranging from CMTS?}
+    Abort -- Yes --> Error
+    Abort -- No --> Adjust[Adjust local parameters per RNG-RSP]
+    Adjust --> Operational
+    T0906660-98/d105
+  
+```
+
+Flowchart for Periodic Ranging - CM View. The process starts at 'Operational', leading to a 'Wait for Station Maintenance opportunity' state. From there, it branches into 'Station Maintenance opportunity' (leading to 'Send RNG-REQ') and 'Timeout T4' (leading to 'Error: Re-initialize MAC'). 'Send RNG-REQ' leads to 'RNG-RSP', which then leads to a decision 'Abort ranging from CMTS?'. If 'Yes', it leads to 'Error: Re-initialize MAC'. If 'No', it leads to 'Adjust local parameters per RNG-RSP', which then loops back to 'Operational'. A small code 'T0906660-98/d105' is at the bottom right.
+
+Figure B.7-13/J.112 – Periodic Ranging – CM View
+
+#### B.7.2.15 Changing upstream burst parameters
+
+Whenever the CMTS is to change any of the upstream burst characteristics, it must provide for an orderly transition from the old values to the new values by all CMs. Whenever the CMTS is to change any of the upstream burst values, it MUST:
+
+- Announce the new values in an Upstream Channel Descriptor message. The Configuration Change Count field must be incremented to indicate that a value has changed.
+
+After transmitting one or more UCD messages with the new value, the CMTS transmits a MAP message with a UCD Count matching the new Configuration Change Count. The first interval in the MAP MUST be a data grant of at least 1 ms to the null Service ID (zero). That is, the CMTS MUST allow one millisecond for cable modems to change their PMD sublayer parameters to match the new set. This millisecond is in addition to other MAP timing constraints (see B.6.4.2).
+
+- The CMTS MUST NOT transmit MAPs with the old UCD Count after transmitting the new UCD.
+
+The CM MUST use the parameters from the UCD corresponding to the MAP's "UCD Count" for any transmissions it makes in response to that MAP. If the CM has, for any reason, not received the corresponding UCD, it cannot transmit during the interval described by that MAP.
+
+#### B.7.2.16 Changing upstream channels
+
+At any time after registration, the CMTS MAY direct the CM to change its upstream channel. This may be done for traffic balancing, noise avoidance, or any of a number of other reasons which are beyond the scope of this specification. Figure B.7-14 shows the procedure that MUST be followed by the CMTS. Figure B.7-15 shows the corresponding procedure at the CM.
+
+Note that if the CMTS retries the UCC-REQ, the CM may have already changed channels (if the UCC-RSP was lost in transit). Consequently, the CMTS MUST listen for the UCC-RSP on both the old and the new channels.
+
+The CM MUST successfully establish initial ranging on a new channel before using that channel. It MUST NOT perform re-registration, since its provisioning and MAC domain remain valid on the new channel. If the CM has previously established ranging on the new channel, and if that ranging on that channel is still current (T4 has not elapsed since the last successful ranging), then the CM MAY use cached ranging information and may omit initial ranging.
+
+#### B.7.2.17 Fault detection and recovery
+
+Fault detection and recovery occurs at multiple levels:
+
+- At the physical level, FEC is used to correct errors where possible – refer to B.4 for details.
+- The MAC protocol protects against errors through the use of checksum fields across both the MAC Header and the data portions of the packet – refer to B.6 for details.
+- All MAC management messages are protected with a CRC covering the entire message, as defined in B.6. Any message with a bad CRC MUST be discarded by the receiver.
+
+Table B.7-1 shows the recovery process that MUST be taken following the loss of a specific type of MAC message.
+
+Messages at the network layer and above are considered to be data packets by the MAC sublayer. These are protected by the CRC field of the data packet and any packets with bad CRCs are discarded. Recovery from these lost packets is in accordance with the upper layer protocol.
+
+![Flowchart illustrating the process of changing upstream channels from the CMTS view. The process starts with 'Decide to switch CM to new upstream channel', followed by 'UCC-REQ', 'Wait for UCC-RSP', a 'Timeout T5' and 'UCC-RSP' parallel path, a 'Retries exhausted?' decision, and ends with 'CM is unreachable' or 'Done'.](b4e87dd6dfd65e6398a50b237cf9d268_img.jpg)
+
+```
+graph TD; A([Decide to switch CM to new upstream channel]) --> B[/UCC-REQ/]; B --> C([Wait for UCC-RSP]); C --> D{ }; D -- Timeout T5 --> E{Retries exhausted?}; D -- UCC-RSP --> F([Done]); E -- No --> B; E -- Yes --> G([CM is unreachable]);
+```
+
+The flowchart shows the following steps: 1. A decision block 'Decide to switch CM to new upstream channel' leads to a message block 'UCC-REQ'. 2. 'UCC-REQ' leads to a wait block 'Wait for UCC-RSP'. 3. From 'Wait for UCC-RSP', the path splits into two parallel options: 'Timeout T5' and 'UCC-RSP'. 4. The 'Timeout T5' path leads to a decision block 'Retries exhausted?'. 5. If 'Retries exhausted?' is 'No', the path loops back to the 'UCC-REQ' block. 6. If 'Retries exhausted?' is 'Yes', the path leads to a terminal block 'CM is unreachable'. 7. The 'UCC-RSP' path leads to a terminal block 'Done'. 8. A small text label 'T0905230-97/d106' is located below the 'Done' block.
+
+Flowchart illustrating the process of changing upstream channels from the CMTS view. The process starts with 'Decide to switch CM to new upstream channel', followed by 'UCC-REQ', 'Wait for UCC-RSP', a 'Timeout T5' and 'UCC-RSP' parallel path, a 'Retries exhausted?' decision, and ends with 'CM is unreachable' or 'Done'.
+
+Figure B.7-14/J.112 – Changing upstream channels – CMTS view
+
+![Flowchart for Changing Upstream Channels – CM view. The process starts at 'Operational', followed by 'UCC-REQ'. A decision 'Already using this channel?' follows. If 'Yes', it goes to 'UCC-RSP' and loops back to 'Operational'. If 'No', it goes to 'UCC-RSP', then 'Switch to new channel and Perform Ranging'. A decision 'Successful Ranging?' follows. If 'Yes', it loops back to 'Operational'. If 'No', it goes to 'Re-initialize MAC'.](bb8035cd106b4d77b3615e90645f8e37_img.jpg)
+
+```
+
+graph TD
+    Operational([Operational]) --> UCC_REQ[/UCC-REQ/]
+    UCC_REQ --> AlreadyUsing{Already using this channel?}
+    AlreadyUsing -- Yes --> UCC_RSP1[/UCC-RSP/]
+    UCC_RSP1 --> Operational
+    AlreadyUsing -- No --> UCC_RSP2[/UCC-RSP/]
+    UCC_RSP2 --> Switch[Switch to new channel and Perform Ranging]
+    Switch --> Successful{Successful Ranging?}
+    Successful -- Yes --> Operational
+    Successful -- No --> ReInit[Re-initialize MAC]
+  
+```
+
+T0905240-97/d107
+
+Flowchart for Changing Upstream Channels – CM view. The process starts at 'Operational', followed by 'UCC-REQ'. A decision 'Already using this channel?' follows. If 'Yes', it goes to 'UCC-RSP' and loops back to 'Operational'. If 'No', it goes to 'UCC-RSP', then 'Switch to new channel and Perform Ranging'. A decision 'Successful Ranging?' follows. If 'Yes', it loops back to 'Operational'. If 'No', it goes to 'Re-initialize MAC'.
+
+**Figure B.7-15/J.112 – Changing Upstream Channels – CM view**
+
+**Table B.7-1/J.112 – Recovery process on loss of specific MAC messages**
+
+| Message name       | Action following message loss                                                                                                                                                                                                                                                                                                                                 |
+|--------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| SYNC               | The CM can lose SYNC messages for a period of the loss SYNC interval (see Appendix B.II) before it has lost synchronization with the network. When this occurs, it follows the same procedures to re-acquire connectivity as during initialization.                                                                                                           |
+| UCD                | A CM MUST receive a valid UCD before transmitting on the upstream. Failure to receive a valid UCD within the timeout period MUST cause the modem to reset and re-initialize its MAC connection.                                                                                                                                                               |
+| MAP                | A CM MUST NOT transmit without a valid upstream bandwidth allocation. If a MAP is missed due to error, the CM MUST NOT transmit for the period covered by the MAP.                                                                                                                                                                                            |
+| RNG-REQ<br>RNG-RSP | If a CM fails to receive a valid Ranging Response within a defined timeout period after transmitting a request, the request MUST be retried a number of times (as defined in Appendix B.II). Failure to receive a valid Ranging Response after the requisite number of attempts MUST cause the modem to reset and re-initialize its MAC connection.           |
+| REG-REQ<br>REG-RSP | If a CM fails to receive a valid registration response within a defined timeout period after transmitting a request, the request will be retried a number of times (as defined in Appendix B.II). Failure to receive a valid registration response after the requisite number of attempts will cause the modem to reset and re-initialize its MAC connection. |
+| UCC-REQ<br>UCC-RSP | If a CMTS fails to receive a valid upstream channel change response within a defined timeout period after transmitting a request, the request MUST be retried a number of times (as defined in Appendix B.II). Failure to receive a valid response after the requisite number of attempts MUST cause the CMTS to consider the CM as unreachable.              |
+
+#### **B.7.2.18 Prevention of unauthorized transmissions**
+
+A CM SHOULD include a means for terminating RF transmission if it detects that its own carrier has been on continuously for longer than the longest possible valid transmission.
+
+### **B.8 Supporting future new cable modem capabilities**
+
+#### **B.8.1 Setting up communications on an enhanced basis**
+
+In the future, new types of CM or CMTS with enhanced characteristics may be introduced. Future-proofing is provided, in the protocols described herein, to permit these new types of CM or CMTS to set up communication on an enhanced basis.
+
+Two methods are provided to accomplish this: one for use when the downstream channel supports upstream channels of varying capability and the other for the case where enhanced downstream channels are available.
+
+##### **B.8.1.1 Upstream enhanced / Downstream standard**
+
+The procedure MUST be as follows:
+
+- a) The enhanced CM acquires a standard downstream CMTS signal.
+- b) The CM receives and interprets Upstream Channel Descriptor (UCD) messages forwarded from the CMTS until it finds one for a channel with the enhanced characteristics which it wishes to use. It joins the upstream transmission stream of this channel which has been assigned to enhanced CMs in accordance with the information in the downstream CMTS signal.
+
+##### **B.8.1.2 Downstream enhanced / Upstream enhanced or standard**
+
+The procedure MUST be as follows:
+
+- a) The enhanced CM acquires a standard downstream CMTS signal.
+- b) The CM receives and interprets Upstream Channel Descriptor (UCD) messages forwarded from the CMTS until it finds one for a channel with the best match to the enhanced characteristics which it wishes to use. It joins the upstream transmission stream of this channel which has been assigned to enhanced CMs in accordance with the information in the downstream CMTS signal.
+- c) The enhanced CM interacts with the provisioning server for the purposes of agreeing upon the operating frequencies, modulation, data rate and other characteristics for enhanced operation.
+- d) The enhanced CM changes operating frequencies and other characteristics accordingly, if necessary, and commences enhanced operation on a different downstream channel, if necessary, under conditions that will not interfere with the standard CMs.
+- e) The CM acquires the new downstream CMTS signal and waits on appropriate UCD on this new channel.
+
+#### **B.8.2 Downloading cable modem operating software**
+
+A CMTS SHOULD be capable of being remotely reprogrammed in the field via a software download via the network.
+
+The cable modem device MUST be capable of being remotely reprogrammed in the field via a software download over the network. This software download capability MUST allow the functionality of the cable modem to be changed without requiring that cable system personnel physically revisit and reconfigure each unit. It is expected that this field programmability will be used to upgrade cable modem software to improve performance, accommodate new functions and features (such as enhanced class of service support), correct any design deficiencies discovered in the software, and to allow a migration path as the Data Over Cable Interface Specification evolves.
+
+The mechanism used for download MUST be TFTP file transfer. The mechanism by which transfers are secured and authenticated is in [MCNS2]. The transfer MUST be initiated in one of two ways:
+
+- An SNMP manager requests the CM to upgrade.
+- The configuration parameter file delivered to the CM from the provisioning server MUST include the desired filename from which the desired software image can be retrieved. If the filename does not match the current software image of the CM, the CM MUST request the specified file from a TFTP server.
+
+The CM MUST write the new software image to non-volatile storage. Once the file transfer is complete, the CM MUST restart itself with the new code image.
+
+If the CM is unable to complete the file transfer for any reason, it MUST remain capable of accepting new software downloads, even if power is interrupted between attempts. The CM MUST log the failure and MAY report it asynchronously to the network manager.
+
+Following upgrade of the operational software, the CM MAY need to follow one of the procedures described above in order to change channels to use the enhanced functionality.
+
+If the CM is to continue to operate in the same upstream and downstream channels as before the upgrade, then it MUST be capable of inter-working with other CMs which MAY be running previous releases of software.
+
+Where software has been upgraded to meet a new version of the specification, then it is critical that it MUST inter-work with the previous version in order to allow a gradual transition of units on the network.
+
+The periodic SYNC message transmitted on the downstream channel MUST indicate the protocol revision at which the channel is operating.
+
+## **B.9 Provision for other future capabilities**
+
+It is anticipated that cable modem networks will, in the future, support capabilities that cannot be adequately defined today. These capabilities may include:
+
+- new physical-layer modulation encoding;
+- improvements to, or new configuration settings within, the defined physical-layer encoding;
+- differing traffic flows and classes of service (e.g. STM telephony).
+
+It is the intent of this specification to provide for interoperability with future devices and networks to whatever extent is practical. The minimum level of interoperability is that future-capability modems and modems conforming to this specification are assigned to different frequency bands, and all modems can automatically scan to find a congenial frequency band.
+
+### **B.9.1 Anticipated physical-layer changes**
+
+Existing MAC signalling provides for optional transmitter equalization (see B.6.3.2.5).
+
+Other forms of upstream transmission manipulation, such as Tomlinson-Harashima precoding, may be developed in the future. Signalling to support such can be added as optional TLV-encodings for the Ranging Response message.
+
+This configuration setting can be phased into existing networks without placing new requirements on existing devices.
+
+When developing a new network, it may be necessary to know modem capabilities before coming to rely on a feature like this. The "Modem Capabilities" mask, exchanged as part of the CM-to-CMTS registration process (see B.6.3.2.7) is intended to provide this information.
+
+#### **B.9.1.1 Adding upstream channel and burst configuration settings**
+
+In future, configuration settings may be provided for new upstream channel characteristics:
+
+- Higher-symbol-rate signalling
+
+and new upstream burst characteristics:
+
+- Trellis-coded modulation (2 bits/sym and 4 bits/sym)
+- Interleaving within a burst.
+
+These are defined through new encodings of the Upstream Channel Descriptor. A CM which finds characteristics which it does not implement is required to either abstain from that burst type, or to find a different upstream channel (see B.8.1.1). This is also controllable by administrative policy if enough commonality is present to complete the registration process.
+
+As with transmission precoding, a modem-capabilities flag may be needed if the CMTS is to choose least-common-denominator capability.
+
+#### B.9.1.1.1 Channel burst parameters for advanced modems
+
+Configuration settings for channel burst parameters for advanced modems are given in Table B.9-1.
+
+It should be possible to program these capabilities separately to users on a given channel. For example, two users should be able to be commanded to operate at a given channel frequency and symbol rate, with one user having any or all of these features: 8 PSK TCM, Interleaving, and TH Precoding; while the other user employs QPSK and none of the other features (i.e. this user is not an advanced cable modem).
+
+**Table B.9-1/J.112 – Channel burst parameters for advanced modems**
+
+| Parameter                                                        | Configuration settings                                                                                                                                                             |
+|------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Modulation<br>(additional configuration settings)                | Trellis Coded Modulation available:<br>1) 8 PSK-2 bits/s (analogous to QPSK);<br>2) 32 QAM-4 bits/s (analogous to 16 QAM).<br>2 encoder configuration settings available for each. |
+| Interleaving<br>N rows by M columns<br>transmitter fills columns | N = 0 to 255; 0 = no interleaving<br>M = 1 to 256                                                                                                                                  |
+| Tomlinson-Harashima Precoding                                    | 1) TH Precoding<br>2) Conventional transmit FIR equalization<br>3) None                                                                                                            |
+
+#### B.9.1.2 Downstream channel improvements
+
+Downstream channel improvements may require additional frequencies to implement for interoperability. The modem initialization process defined herein provides that if the CM is unable to complete satisfactory exchanges with the CMTS, then it will scan for a more suitable frequency (see B.8.1.2).
+
+#### B.9.2 New network service requirements
+
+The types of network service expected on a cable network are apt to change over the lifetime of equipment conforming to this specification. This specification anticipates use of ATM-style traffic parameters by giving the CMTS centralized control over bandwidth allocation and jitter. Future networks may include classes of data other than those explicitly provided (802-like and ATM). These may be implemented by using the Reserved code point in the MAC FC field. Because this specification does not require a particular bandwidth allocation algorithm, future algorithms may be developed which take into account policies and traffic types that are not yet well-understood.
+
+### B.9.2.1 Multicast Service IDs
+
+Multicast Service IDs provide extensibility to the interval usage codes that are defined herein in the upstream bandwidth allocation map. The multicast ID reflects, not just group membership, but also the access rules that apply to whatever interval is assigned to that ID. The following examples of Request/Data IEs illustrate some of the possibilities for use of a particular ID:
+
+- the grant is for contention space for all high-priority (as defined locally) data PDUs from a select group of CMs;
+- the grant is for ATM cells only.
+
+It may be necessary to develop an extension to the MAC signalling protocol to distribute the definition of attributes associated with particular multicast Service IDs.
+
+### B.9.2.2 RSVP support for upstream traffic
+
+The Resource ReSerVation Protocol (RSVP) is a resource reservation set-up protocol currently being standardized by the Internet Engineering Task Force. RSVP provides receiver-initiated set-up of resource reservations for multicast and unicast data flows. This subclause serves to anticipate and guide the definition of new MAC management messages to support resource reservation for upstream traffic in the Data-over-Cable context.
+
+RSVP assumes the implementation of two modules on each RSVP-capable node to forward data packets: the "packet classifier" and the "packet scheduler". The packet classifier determines the route and class-of-service class for each packet, and sends the packet to the packet scheduler. The RSVP packet classifier uses a "filter spec" (which matches a particular source IP address and TCP/UDP port number) to classify and restrict traffic that consumes reservation resources. The packet scheduler makes packet forwarding decisions (e.g. queuing decisions) to achieve the promised class of service on the interface. The RSVP packet scheduler uses a "flow spec" (which identifies token bucket parameters, peak data rate, etc.) to identify the desired class of service.
+
+In the context of RSVP for upstream traffic in the data-over-cable system, it is desirable for the CM to perform the "packet classifier" function; however the CMTS should perform most of the "packet scheduler" function. The support for this split of functions suggests the future definition of three new MAC management messages: "Dynamic Service Addition", "Dynamic Service Deletion", and "Dynamic Service Response."
+
+The Dynamic Service Addition message is periodically transmitted from the CMTS to the CM to announce the allocation of a new SID. The Dynamic Service Addition message contains the new SID value, and type/length/value fields which can encode the RSVP filter specification and RSVP "clean-up timeout" interval (to support the RSVP "soft state" approach). The CM is expected to use the new SID exclusively for upstream traffic that matches the filter specification. The CM should assume that the new SID is refreshed by the receipt of another Dynamic Service Addition message within the clean-up timeout interval; otherwise, the SID is ignored by the CM at the conclusion of the interval.
+
+The Dynamic Service Deletion message is transmitted from the CMTS to the CM to delete an unused SID immediately (to support the RSVP explicit "teardown" message). The Dynamic Service Response message is transmitted from the CM to the CMTS to acknowledge receipt of a Dynamic Service Addition or Dynamic Service Deletion message.
+
+The interaction between RSVP "Path" and "Resv" messages, and the Dynamic Service Addition and Dynamic Service Response messages, is proposed to be as follows:
+
+- 1) The data flow source-node (behind a CM) generates an RSVP Path message, and sends the message toward the data flow destination-node.
+- 2) The CM forwards the upstream RSVP Path message to the destination-node without processing.
+- 3) The CMTS intercepts the upstream RSVP Path message, stores "path state" from the message, updates the "previous hop address" in the message, and forwards the message.
+- 4) The data flow destination-node receives the RSVP Path message, and replies with an RSVP Resv message to request a reservation of resources for the data flow from the source-node to itself. The RSVP Resv message is sent to the "previous hop" of the Path message – the CMTS.
+
+- 5) The CMTS receives the downstream RSVP Resv message, and processes the message flow spec using its "admission control" and "policy control" modules (in cooperation with the CMTS upstream bandwidth scheduler). Note that the CMTS must account for available resources on the CMTS-NSI as well as the RFI. The rest of this subclause assumes that the reservation message is accepted by the CMTS.
+- 6) The CMTS sends the "Dynamic Service Addition" MAC message to the CM. The message includes a new SID and the "filter spec" from the RSVP Resv message.
+- 7) The CM receives the "Dynamic Service Addition" MAC message, stores the new SID and "filter spec", and sends the "Dynamic Service Response" MAC message to the CMTS.
+- 8) The CMTS receives the "Dynamic Service Response" MAC message, and forwards the RSVP Resv message to its "previous hop."
+- 9) The CM forwards the downstream RSVP Resv message to the source-node without processing.
+
+### **B.9.3 PID filtering capability**
+
+This specification uses a single well-known PID for all data-over-cable traffic. CMs MAY use additional PIDs for differentiation of traffic types or to provide streams to individual CMs. PID assignments MAY be facilitated by the appropriate MAC control message extensions. As an example, this could facilitate services that use MPEG packet-level encryption. Any such services are beyond the scope of this version of the specification.
+
+An additional modem capability configuration setting could be added in the Registration Request (REG-REQ) message to indicate the number of PIDs, in addition to the well-known PID, that the CM can filter. A "0" would indicate that the CM can only filter on the well-known PID.
+
+An extension to the encodings in the Registration Response (REG-RSP) could be used to assign to a CM additional PIDs on which to filter.
+
+## Appendix B.I
+
+### Well-Known Addresses
+
+#### B.I.1 MAC addresses
+
+MAC addresses described here are defined using the Ethernet/ISO IEC 8802-3 convention as bit-little-indian.
+
+The following multicast address MUST be used to address the set of all CM MAC sublayers; for example, when transmitting Allocation Map PDUs.
+
+01-E0-2F-00-00-01
+
+The following multicast address MUST be used to address all CMTSs within the MAC-sublayer domain:
+
+01-E0-2F-00-00-02
+
+Note that in nearly all cases the unicast CMTS address is preferred. The address range:
+
+01-E0-2F-00-00-03 through 01-E0-2F-00-00-0F
+
+is reserved for future definition. Frames addressed to any of these addresses SHOULD NOT be forwarded out of the MAC-sublayer domain.
+
+#### B.I.2 MAC Service IDs
+
+The following MAC Service IDs have assigned meanings. Those not included in this table are available for assignment, either by the CMTS or administratively.
+
+- 0x0000 Addressed to no CM.
+- 0x3FFF Addressed to all CMs.
+- 0x3FF1-0x3FFE Addressed to all CMs. Available for small data PDUs, as well as requests (used only with request/data IEs). The last digit indicates the frame length and transmission opportunities as follows.
+- 0x3FF1 Within the interval specified, a transmission may start at any mini-slot, and must fit within one mini-slot.
+- 0x3FF2 Within the interval specified, a transmission may start at every other mini-slot, and must fit within two mini-slots (e.g. a station may start transmission on the first mini-slot within the interval, the third mini-slot, the fifth, etc.).
+- 0x3FF3 Within the interval specified, a transmission may start at any third mini-slot, and must fit within three mini-slots (e.g. starts at first, fourth, seventh, etc.).
+- 0x3FF4 Starts at first, fifth, ninth, etc.
+- ...
+- 0x3FFD Starts at first, fourteenth (14th), twenty-seventh (27th), etc.
+- 0x3FFE Within the interval specified, a transmission may start at any 14th mini-slot, and must fit within 14 mini-slots.
+
+#### B.I.3 MPEG PID
+
+All MCNS data MUST be carried in MPEG-2 packets with the header PID field set to 0x1FFE.
+
+## Appendix B.II
+
+### Parameters and constants
+
+| System     | Name                                | Time reference                                                                                                                                                        | Minimum value   | Default value | Maximum value                  |
+|------------|-------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|---------------|--------------------------------|
+| CMTS       | Sync Interval                       | Nominal time between transmission of SYNC messages (B.6.3.2.1)                                                                                                        |                 |               | 200 ms                         |
+| CMTS       | UCD Interval                        | Time between transmission of UCD messages_ (B.6.3.2.2)                                                                                                                |                 |               | 2 s                            |
+| CMTS       | Max MAP Pending                     | The number of mini-slots that a CMTS is allowed to map into the future (B.6.3.2.3)                                                                                    |                 |               | 4096 mini-slot times           |
+| CMTS       | Ranging Interval                    | Time between transmission of broadcast Ranging Requests (B.6.3.2.4)                                                                                                   |                 |               | 2 s                            |
+| CM         | Lost Sync Interval                  | Time since last received Sync message before synchronization is considered lost                                                                                       |                 |               | 600 ms                         |
+| CM         | Contention Ranging Retries          | Number of Retries on contention Ranging Requests (B.7.2.5)                                                                                                            |                 | 16            |                                |
+| CM, CMTS   | Invited Ranging Retries             | Number of Retries on invited Ranging Requests_(B.7.2.5)                                                                                                               |                 | 16            |                                |
+| CM         | Request Retries                     | Number of retries on bandwidth allocation requests                                                                                                                    |                 | 16            |                                |
+| CM         | Registration Request Retries        | Number of retries on registration requests                                                                                                                            |                 | 3             |                                |
+| CM         | Data Retries                        | Number of retries on immediate data transmission                                                                                                                      |                 | 16            |                                |
+| CMTS       | CM MAP processing time              | Time provided between arrival of the last bit of a MAP at a CM and effectiveness of that MAP (B.6.4.1)                                                                | 200 µs          |               |                                |
+| CMTS       | CM Ranging Response processing time | Minimum time allowed for a CM following receipt of a ranging response before it is expected to reply to an invited Ranging Request                                    | 1 ms            |               |                                |
+| CM         | T1                                  | Wait for UCD timeout.                                                                                                                                                 |                 |               | 5 * UCD interval maximum value |
+| CM         | T2                                  | Wait for broadcast ranging timeout.                                                                                                                                   |                 |               | 5 * ranging interval           |
+| CM         | T3                                  | Wait for Ranging Response.                                                                                                                                            | 50 ms           | 200 ms        | 200 ms                         |
+| CM         | T4                                  | Wait for unicast ranging opportunity. If the pending-till-complete field was used earlier by this modem, then the value of that field must be added to this interval. |                 |               | 30 s                           |
+| CMTS       | T5                                  | Wait for Upstream Channel Change response.                                                                                                                            |                 |               | 2 s                            |
+| CM         | T6                                  | Wait for registration response.                                                                                                                                       |                 |               | 3 s                            |
+| CM<br>CMTS | Mini-slot size                      | Size of mini-slot for upstream transmission. Must be a power of 2 (in units of the Timebase Tick).                                                                    | 32 symbol times |               |                                |
+| CM<br>CMTS | Timebase Tick                       | System timing unit                                                                                                                                                    |                 | 6.25 µs       |                                |
+
+## Appendix B.III
+
+### CM configuration interface specification
+
+#### B.III.1 DHCP fields used by the CM
+
+The following fields are required in the DHCP request from the CM:
+
+- the hardware type SHOULD be set to Ethernet;
+- the hardware address of the CM (used as the key to identify the CM during the DHCP process).
+
+The following fields are required in the DHCP response returned to the CM:
+
+- The IP address to be used by the CM.
+- The subnet mask to be used by the CM.
+- If the DHCP server is on a different network (requiring a relay agent), then the relay agent MUST set the gateway address field of the DHCP response.
+- The name of the CM configuration file to be read from the TFTP server by the CM.
+- The time offset of the CM from Universal Coordinated Time (UTC) – Used by the CM to calculate the local time to use in time-stamping error logs.
+- Time-server option – Provides a list of [RFC-868] time-servers from which the current time may be obtained.
+- The IP address of the next server to use in the bootstrap process (TFTP server) is returned in the siaddr field.
+- The IP address of the security server SHOULD be set if security is required. This is encoded using the code 128 (which is reserved for site specific information per reference [RFC-1533]) as shown below.
+
+| Type | Length | Value           |
+|------|--------|-----------------|
+| 128  | 4      | ip1,ip2,ip3,ip4 |
+
+#### B.III.2 CM binary configuration file format
+
+The CM-specific configuration data MUST be contained in a file which is downloaded to the CM via TFTP. This is a binary file in the same format defined for DHCP vendor extension data [RFC-1533].
+
+It MUST consist of a number of configuration settings (1 per parameter) each of the form:
+
+type : length : valeur
+
+where:
+
+- type is a single-octet identifier which defines the parameter;
+- length is a single octet containing the length of the value field in octets (not including type and length fields);
+- value is from one to 254 octets containing the specific value for the parameter.
+
+The configuration settings MUST follow each other directly in the file, which is a stream of octets (no record markers).
+
+Configuration settings are divided into three types:
+
+- Standard configuration settings which MUST be present;
+- Standard configuration settings which MAY be present;
+- Vendor-specific configuration settings.
+
+CMs MUST be capable of processing all standard configuration settings.
+
+Authentication of the provisioning information is provided by two Message Integrity Check (MIC) configuration settings, CM MIC and CMTS MIC:
+
+- CM MIC is a digest which ensures that the data sent from the provisioning server were not modified en route. This is NOT an authenticated digest (it does not include any shared secret).
+- CMTS MIC is a digest used to authenticate the provisioning server to the CMTS during registration. It is taken over a number of fields one of which is a shared secret between the CMTS and the provisioning server.
+
+Use of the CM MIC allows the CMTS to authenticate the provisioning data without needing to receive the entire file.
+
+Thus the file structure is of the form shown in Figure B.III-1:
+
+![Diagram showing the binary configuration file format with columns for Configuration Setting 1, Configuration Setting 2, Configuration Setting n, CM MIC, and CMTS MIC. A dashed line separates the first two settings from the rest. A small code T0906670-98/d108 is at the bottom right.](a93e145fd70325b1828e19710266906e_img.jpg)
+
+|                         |                         |       |                         |        |          |
+|-------------------------|-------------------------|-------|-------------------------|--------|----------|
+| Configuration Setting 1 | Configuration Setting 2 | ----- | Configuration Setting n | CM MIC | CMTS MIC |
+|-------------------------|-------------------------|-------|-------------------------|--------|----------|
+
+T0906670-98/d108
+
+Diagram showing the binary configuration file format with columns for Configuration Setting 1, Configuration Setting 2, Configuration Setting n, CM MIC, and CMTS MIC. A dashed line separates the first two settings from the rest. A small code T0906670-98/d108 is at the bottom right.
+
+NOTE – Not all configuration settings need to be present in a given file.
+
+**Figure B.III-1/J.112 – Binary configuration file format**
+
+**B.III.3 Configuration file settings**
+
+The following configuration settings MUST be included in the configuration file and MUST be supported by all CMs:
+
+- Network Access Configuration Setting;
+- End Configuration Setting.
+
+The following configuration settings MAY be included in the configuration file and if present MUST be supported by all CMs:
+
+- Downstream Frequency Configuration Setting;
+- Upstream Channel ID Configuration Setting;
+- Class of Service Configuration Setting;
+- Vendor ID Configuration Setting;
+- Baseline Privacy Configuration Setting;
+- Software Upgrade Filename Configuration Setting;
+- SNMP Write-Access Control;
+- SNMP MIB Object;
+- Pad Configuration Setting.
+
+The following configuration setting MAY be included in the configuration file and if present MAY be supported by a CM:
+
+- Vendor-Specific Configuration Settings
+
+**B.III.4 Configuration file creation**
+
+The sequence of operations required to create the configuration file is as shown in Figure B.III-1 through Figure B.III-5.
+
+- 1) Create the type/length/value entries for all the parameters required by the CM.
+
+|                                     |
+|-------------------------------------|
+| type, length, value for parameter 1 |
+| type, length, value for parameter 2 |
+| ...                                 |
+| type, length, value for parameter n |
+
+**Figure B.III-2/J.112 – Create TLV entries for parameters required by the CM**
+
+- 2) Calculate the CM Message Integrity Check (MIC) configuration setting as defined in B.III.5 and add to the file following the last parameter using code and length values defined for this field.
+
+|                                     |
+|-------------------------------------|
+| type, length, value for parameter 1 |
+| type, length, value for parameter 2 |
+| ...                                 |
+| type, length, value for parameter n |
+| type, length, value for CM MIC      |
+
+**Figure B.III-3/J.112 – Add CM MIC**
+
+- 3) Calculate the CMTS Message Integrity Check (MIC) configuration setting as defined in B.III.6 and add to the file following the CM MIC using code and length values defined for this field.
+
+|                                     |
+|-------------------------------------|
+| type, length, value for parameter 1 |
+| type, length, value for parameter 2 |
+| ...                                 |
+| type, length, value for parameter n |
+| type, length, value for CM MIC      |
+| type, length, value for CMTS MIC    |
+
+**Figure B.III-4/J.112 – Add CMTS MIC**
+
+- 4) Add the end of data marker.
+
+|                                     |
+|-------------------------------------|
+| type, length, value for parameter 1 |
+| type, length, value for parameter 2 |
+| ...                                 |
+| type, length, value for parameter n |
+| type, length, value for CM MIC      |
+| type, length, value for CMTS MIC    |
+| end of data marker                  |
+
+**Figure B.III-5/J.112 – Add end of data marker**
+
+### **B.III.5 CM MIC calculation**
+
+The CM message integrity check configuration setting MUST be calculated by performing an MD5 digest over the bytes of the configuration setting field. It is calculated over the bytes of these settings as they appear in the TFTPed image, without regard to TLV ordering or contents. There are two exceptions to this disregard of the contents of the TFTPed image:
+
+- 1) The bytes of the CM MIC TLV itself are omitted from the calculation. This includes the type, length, and value fields.
+- 2) The bytes of the CMTS MIC TLV are omitted from the calculation. This includes the type, length, and value fields.
+
+On receipt of a configuration file, the CM MUST recompute the digest and compare it to the CM MIC configuration setting in the file. If the digests do not match, then the configuration file MUST be discarded.
+
+### **B.III.6 CMTS MIC calculation**
+
+The CMTS message integrity check configuration setting MUST be calculated by performing an MD5 digest over the following configuration setting fields, when present in the configuration file, in the order shown:
+
+- Downstream Frequency Configuration Setting;
+- Upstream Channel ID Configuration Setting;
+- Network Access Configuration Setting;
+- Class of Service Configuration Setting;
+- Vendor ID Configuration Setting;
+- Baseline Privacy Configuration Setting;
+- Vendor specific Configuration Settings;
+- CM MIC Configuration Setting;
+- Authentication string.
+
+The configuration setting fields are treated as if they were contiguous data when calculating the MD5 digest.
+
+The digest MUST be added to the configuration file as its own configuration setting field using the CMTS MIC Configuration Setting encoding.
+
+The authentication string is a shared secret between the provisioning server (which creates the configuration files) and the CMTS. It allows the CMTS to authenticate the CM provisioning.
+
+The mechanism by which the shared secret is managed is up to the system operator.
+
+On receipt of a configuration file, the CM MUST forward the CMTS MIC as part of the registration request (REG-REQ).
+
+On receipt of a REG-REQ, the CMTS MUST recompute the digest over the included fields and the authentication string and compare it to the CMTS MIC configuration setting in the file. If the digests do not match, the registration request MUST be rejected by setting the authentication failure result in the registration response status field.
+
+#### **B.III.6.1 Digest calculation**
+
+The digest fields MUST be calculated using the mechanism defined in [RFC-2104].
+
+### **B.III.7 Registration configuration settings**
+
+The following configuration settings are used in the registration messages. Refer to B.6.3.2 for details on these messages.
+
+#### **Registration Request**
+
+- Downstream Frequency Configuration Setting;
+- Upstream Channel ID Configuration Setting;
+- Network Access Configuration Setting;
+
+- Class of Service Configuration Setting;
+- Modem Capabilities Configuration Setting;
+- Vendor ID Configuration Setting;
+- Baseline Privacy Configuration Setting;
+- Vendor specific extensions;
+- CM MIC;
+- CMTS MIC;
+- Modem IP address.
+
+**Registration Response**
+
+- Class of Service Configuration Setting;
+- Modem Capabilities Configuration Setting;
+- Vendor ID Configuration Setting;
+- Vendor-Specific extensions.
+
+**B.III.8 Encodings**
+
+The following type/length/value encodings MUST be used in both the configuration file and in CM registration requests and CMTS responses. All multi-octet quantities are in network-byte order, i.e. the octet containing the most-significant bits is the first transmitted on the wire.
+
+The following configuration settings MUST be supported by all CMs which are compliant with this specification.
+
+**B.III.8.1 End-of-data marker**
+
+This is a special marker for end of data.
+
+It has no length or value fields:
+
+type  
+255
+
+**B.III.8.2 Pad configuration setting**
+
+This has no length or value fields and is only used following the end of data marker to pad the file to an integral number of 32-bit words.
+
+type  
+0
+
+**B.III.8.3 Downstream frequency configuration setting**
+
+The receive frequency to be used by the CM. It is an override for the channel selected during scanning. This is the center frequency of the downstream channel in Hz stored as a 32-bit binary number.
+
+| Type | Length | rx frequency    |
+|------|--------|-----------------|
+| 1    | 4      | rx1 rx2 rx3 rx4 |
+
+**Valid range**
+
+The receive frequency MUST be a multiple of 62 500 Hz.
+
+#### **B.III.8.4 Upstream channel ID configuration setting**
+
+The upstream channel ID which the CM MUST use. The CM MUST listen on the defined downstream channel until an upstream channel description message with this ID is found. It is an override for the channel selected during initialization.
+
+| <b>Type</b> | <b>Length</b> | <b>Value</b> |
+|-------------|---------------|--------------|
+| 2           | 1             | channel ID   |
+
+#### **B.III.8.5 Network Access Control Object**
+
+If the value field is a 1 this CM is allowed access to the network; if a 0 it is not.
+
+| <b>Type</b> | <b>Length</b> | <b>On/Off</b> |
+|-------------|---------------|---------------|
+| 3           | 1             | 1 or 0        |
+
+#### **B.III.8.6 Class of Service Configuration Setting**
+
+This field defines the parameters associated with a class of service. It is somewhat complex in that is composed from a number of encapsulated type/length/value fields. The encapsulated fields define the particular class of service parameters for the class of service in question. Note that the type fields defined are only valid within the encapsulated class of service configuration setting string. A single class of service configuration setting is used to define the parameters for a single service class. Multiple class definitions use multiple class of service configuration setting sets.
+
+| <b>Type</b> | <b>Length</b> | <b>Value</b> |
+|-------------|---------------|--------------|
+| 4           | n             |              |
+
+##### **B.III.8.6.1 Internal class of service encodings**
+
+###### **B.III.8.6.1.1 Class ID**
+
+The value of the field specifies the identifier for the class of service to which the encapsulated string applies.
+
+| <b>Type</b> | <b>Length</b> | <b>Value</b> |
+|-------------|---------------|--------------|
+| 1           | 1             |              |
+
+##### **Valid range**
+
+The class ID MUST be in the range 1 to 16.
+
+###### **B.III.8.6.1.2 Maximum downstream rate configuration setting**
+
+The value of the field specifies the maximum data rate in bit/s allowed from this service class on the downstream path. That is, it is the peak data rate for Packet PDU data (including destination MAC address and the CRC) over a one-second interval. This is a limit on the modem, not a guarantee that this rate is available
+
+| <b>Type</b> | <b>Length</b> | <b>Value</b> |
+|-------------|---------------|--------------|
+| 2           | 4             |              |
+
+#### B.III.8.6.1.3 Maximum upstream rate configuration setting
+
+The value of the field specifies the maximum data rate in bit/s allowed from this service class on the upstream channel. That is, it is the peak data rate for Packet PDU data (including destination MAC address and the CRC) over a one-second interval. This is a limit on the modem, not a guarantee that this rate is available.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 3    | 4      |       |
+
+#### B.III.8.6.1.4 Upstream channel priority configuration setting
+
+The value of the field specifies the relative priority assigned to this service class for data transmission in the upstream channel. Higher numbers indicate higher priority.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 4    | 1      |       |
+
+#### Valid range
+
+0 → 7
+
+#### B.III.8.6.1.5 Guaranteed minimum upstream channel data rate configuration setting
+
+The value of the field specifies the data rate in bit/s which will be guaranteed to this service class on the upstream channel.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 5    | 4      |       |
+
+#### B.III.8.6.1.6 Maximum upstream channel transmit burst configuration setting
+
+The value of the field specifies the maximum transmit burst (in units of mini-slots) which this service class is allowed on the upstream channel.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 6    | 2      | 255   |
+
+#### Valid range
+
+0 → 255 for initial version.
+
+NOTE – The 2-byte length field is retained to support possible future expansion of allowed burst sizes.
+
+#### B.III.8.6.1.7 Class of service privacy enable
+
+This configuration setting enables/disables Baseline Privacy on a provisioned COS. See [MCNS8].
+
+| Type                | Length | Enable/Disable |
+|---------------------|--------|----------------|
+| 7 (= CoS_BP_ENABLE) | 1      | 1 or 0         |
+
+**Table B.III-1/J.112 – Sample Class of Service Encoding**
+
+| Type | Length | Value (sub)type            | Length                     | Value                                              |                                                                                                                                                                                                                                  |
+|------|--------|----------------------------|----------------------------|----------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 4    | 28     | 1<br>2<br>3<br>4<br>5<br>6 | 1<br>4<br>4<br>1<br>4<br>2 | 1<br>10 000 000<br>2 000 000<br>5<br>64 000<br>100 | Class of service configuration setting<br>Service class 1<br>Max. forward rate of 10 Mbit/s<br>Max. return rate of 2 Mbit/s<br>Return path priority of 5<br>Min. guaranteed 64 kb/s<br>Max. transmission burst of 100 mini-slots |
+| 4    | 28     | 1<br>2<br>3<br>4<br>5<br>6 | 1<br>4<br>4<br>1<br>4<br>2 | 2<br>5 000 000<br>1 000 000<br>3<br>32 000<br>50   | Class of service configuration setting<br>Service class 2<br>Max. forward rate of 5 Mbit/s<br>Max. return rate of 1 Mbit/s<br>Return path priority of 3<br>Min. guaranteed 32 kb/s<br>Max. transmission burst of 50 mini-slots   |
+
+### B.III.8.7 Modem capabilities configuration setting
+
+The value field describes the capabilities of a particular modem, i.e. those OPTIONAL features which the modem can support. It is composed from a number of encapsulated type/length/value fields. The encapsulated fields define the specific capabilities for the modem in question. Note that the type fields defined are only valid within the encapsulated capabilities configuration setting string.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 5    | n      |       |
+
+The set of possible encapsulated fields is described below.
+
+#### B.III.8.7.1 Concatenation support
+
+If the value field is a 1, this modem can support concatenation; if a 0 it cannot.
+
+| Type | Length | On/Off |
+|------|--------|--------|
+| 1    | 1      | 1 or 0 |
+
+**Table B.III-2/J.112 – Sample capability encoding**
+
+| Type | Length | Value (sub)type | Length | Value |                                                                   |
+|------|--------|-----------------|--------|-------|-------------------------------------------------------------------|
+| 5    |        | 1               | 1      | 1     | Modem capability configuration setting<br>concatenation supported |
+
+### B.III.8.8 CM Message Integrity Check (MIC) configuration setting
+
+The value field contains the CM message integrity check code. This is used to detect unauthorized modification or corruption of the configuration file.
+
+| Type | Length | Value         |
+|------|--------|---------------|
+| 6    | 16     | d1 d2 ... d16 |
+
+### B.III.8.9 CMTS Message Integrity Check (MIC) configuration setting
+
+The value field contains the CMTS message integrity check code. This is used to detect unauthorized modification or corruption of the configuration file.
+
+| Type | Length | Value         |
+|------|--------|---------------|
+| 7    | 16     | d1 d2 ... d16 |
+
+### B.III.8.10 Vendor ID configuration setting
+
+The value field contains the vendor identification specified by the three-byte vendor-specific Organization Unique Identifier of the CM MAC address.
+
+| Type | Length | Value      |
+|------|--------|------------|
+| 8    | 3      | v1, v2, v3 |
+
+### B.III.8.11 Software upgrade filename
+
+The filename of the software upgrade file for the CM. This is a filename only, not a complete path. The file should reside in the TFTP public directory.
+
+| Type | Length | Value    |
+|------|--------|----------|
+| 9    | n      | Filename |
+
+NOTE – Filename length MUST be less than or equal to 64 bytes.
+
+### B.III.8.12 SNMP write-access control
+
+This object makes it possible to disable SNMP "Set" access to individual MIB objects. Each instance of this object controls access to all of the writeable MIB objects whose Object ID (OID) prefix matches. This object may be repeated to disable access to any number of MIB objects.
+
+| Type | Length | Value                        |
+|------|--------|------------------------------|
+| 10   | n      | OID prefix plus control flag |
+
+where n is the size of the ASN.1 Basic Encoding Rules [ISO/IEC 8825] encoding of the OID prefix plus one byte for the control flag.
+
+The control flag may take values:
+
+- 0 Allow write-access
+- 1 Disallow write-access
+
+Any OID prefix may be used. The Null OID 0.0 may be used to control access to all MIB objects. (The OID 1.3.6.1 will have the same effect.)
+
+When multiple instances of this object are present and overlap, the longest (most specific) prefix has precedence. Thus, one example might be:
+
+- someTable Disallow write-access
+- someTable.1.3 Allow write-access
+
+This example disallows access to all objects in someTable except for someTable.1.3.
+
+### B.III.8.13 SNMP MIB object
+
+This object allows arbitrary SNMP MIB objects to be set via the TFTP-Registration process.
+
+| Type | Length | Value            |
+|------|--------|------------------|
+| 11   | n      | Variable binding |
+
+where the value is an SNMP VarBind as defined in [RFC-1157]. The VarBind is encoded in ASN.1 Basic Encoding Rules, just as it would be if part of an SNMP Set request.
+
+The cable modem MUST treat this object as if it were part of an SNMP Set Request with the following caveats:
+
+- It MUST treat the request as fully authorized (it cannot refuse the request for lack of privilege).
+- SNMP Write-Control provisions (see previous subclause) do not apply.
+- No SNMP response is generated by the CM.
+
+This object MAY be repeated with different VarBinds to "Set" a number of MIB objects. All such Sets MUST be treated as if simultaneous.
+
+Each VarBind MUST be limited to 255 bytes.
+
+### B.III.8.14 Vendor-specific information
+
+Vendor-specific information for cable modems, if present, MUST be encoded in the configuration file using the vendor-specific information code (43) following the rules defined in [RFC-1533]. The vendor identifier field MUST be present if this configuration setting is used. This configuration setting MAY appear multiple times.
+
+| Type | Length | Value                 |
+|------|--------|-----------------------|
+| 43   | n      | Per vendor definition |
+
+### B.III.8.15 Modem IP address
+
+This object informs the CMDS of the provisioned IP address of the cable modem.
+
+| Type | Length | Value      |
+|------|--------|------------|
+| 12   | 4      | IP address |
+
+This object appears only in the Registration Request message.
+
+This address plays no part in the protocols defined in this specification, but is included to assist with network management.
+
+### B.III.8.16 Service(s) not available response
+
+This configuration setting MUST be included in the Registration Response message if the CMDS is unable or unwilling to grant any of the requested classes of service that appeared in the Registration Request. Although the value applies only to the failed service class, the entire Registration Request MUST be considered to have failed (none of the class-of-service configuration settings are granted).
+
+| Type | Length | Value                  |
+|------|--------|------------------------|
+| 13   | 3      | Class ID, type, reason |
+
+where:
+
+- class ID is the class-of-service class from the request which is not available;
+- type is the specific class-of-service object within the class which caused the request to be rejected;
+
+- reason is the reason for the rejection from the following:
+  - reason-other(1);
+  - reason-unrecognized-configuration-setting(2);
+  - reason-temporary(3);
+  - reason-permanent(4).
+
+The reason codes MUST be used in the following way:
+
+- Reason-other(1) is used when none of the other reason codes apply:
+- Reason-unrecognized-configuration-setting(2) is used when a class-of-service type is not recognized or when its value is outside of the specified range.
+- Reason-temporary(3) indicates that the current loading of service IDs or traffic policies at the CMTS prevents granting the request, but that the request might succeed at another time.
+- Reason-permanent(4) indicates that, for policy, configuration, or CMTS capabilities reasons, the request would never be granted unless the CMTS were manually reconfigured or replaced.
+
+#### **B.III.8.17 CPE Ethernet MAC address**
+
+This object configures the CM with the Ethernet MAC address of a CPE device (see B.3.1.2.3.1). This object may be repeated to configure any number of CPE device addresses.
+
+| Type | Length | Value                       |
+|------|--------|-----------------------------|
+| 14   | 6      | Ethernet MAC address of CPE |
+
+This object appears only in the configuration file.
+
+#### **B.III.8.18 Telephone settings option**
+
+This configuration setting describes parameters which are specific to telephone return systems. It is composed from a number of encapsulated type/length/value fields. See [MCNS6].
+
+| Type             | Length | Value |
+|------------------|--------|-------|
+| 15 (= TRI_CFG01) | n      |       |
+
+#### **B.III.8.19 SNMP IP address**
+
+This is the IP address of the SNMP Manager. The CM uses this address to report a problem with the cable network.
+
+| Type             | Length | Value            |
+|------------------|--------|------------------|
+| 16 (= TRI_CFG02) | 4      | IntegerIPaddress |
+
+#### **B.III.8.20 Baseline Privacy configuration settings option**
+
+This configuration setting describes parameters which are specific to Baseline Privacy. It is composed from a number of encapsulated type/length/value fields. See [MCNS8].
+
+| Type          | Length | Value |
+|---------------|--------|-------|
+| 17 (= BP_CFG) | n      |       |
+
+## Appendix B.IV
+
+### MAC sublayer service definition
+
+The MAC sublayer will provide the following services, consistent with [ISO/IEC 15802-1]. This is an internal interface within the CM and CMTS and is provided for reference purposes only.
+
+#### B.IV.1 Service at the CM
+
+The following service primitives are provided by the MAC sublayer to the higher-layer protocol entity. These represent an abstraction of the service provided and do not imply a particular implementation:
+
+MAC\_CM\_802\_DATA.request  
+MAC\_CM\_DIX\_DATA.request  
+MAC\_CM\_ATM\_DATA.request  
+MAC\_CM\_802\_DATA.indication  
+MAC\_CM\_DIX\_DATA.indication  
+MAC\_CM\_ATM\_DATA.indication  
+MAC\_CM\_DATA.acknowledgment
+
+#### B.IV.2 MAC\_CM\_802\_DATA.request
+
+Issued by the higher-layer to request transmission from the CM on an upstream channel. Parameter:
+
+- channel\_ID - MAY be implicit if the device supports attachment to a single channel.
+- service\_ID.
+- contention\_and\_acknowledgment\_constraints – Specifies whether or not this request MAY be satisfied in a contention interval. Ordinarily, the CM will request that contention data be acknowledged by the CMTS.
+- destination\_address.
+- source\_address (OPTIONAL) – If not explicitly overwritten, the address at this MSAP is used.
+- LLC\_pdu.
+- Padding (OPTIONAL) – MAY be used if the LLC PDU is less than 60 bytes and it is desired to maintain ISO 8802-3 transparency.
+- frame\_check\_sequence (OPTIONAL) – MAY be supplied if ISO 8802-3 transparency is desired. Otherwise, a 32-bit CRC sum is calculated by the MAC sublayer.
+- Length.
+
+#### B.IV.3 MAC\_CM\_DIX\_DATA.request
+
+Issued by the higher-layer to request transmission from the CM on an upstream channel. Parameters:
+
+- channel\_ID – MAY be implicit if the device supports attachment to a single channel.
+- service\_ID.
+- contention\_and\_acknowledgment\_constraints – Specifies whether or not this request MAY be satisfied in a contention interval. Ordinarily, the CM will request that contention data be acknowledged by the CMTS.
+- destination\_address.
+- source\_address (OPTIONAL) – If not explicitly overwritten, the address at this MSAP is used.
+- Ethernet type.
+- ethernet\_dix\_pdu.
+- Length.
+
+#### **B.IV.4 MAC\_CM\_ATM\_DATA.request**
+
+Issued by the higher-layer to request transmission from the CM on an upstream channel. Parameters:
+
+- channel\_ID – MAY be implicit if the device supports attachment to a single channel.
+- service\_ID.
+- contention\_and\_acknowledgment\_constraints – Specifies whether or not this request MAY be satisfied in a contention interval. Ordinarily, the CM will request that contention data be acknowledged by the CMTS.
+- One or more ATM cells. Cells need not be within the same virtual circuit or virtual path.
+- Length.
+
+#### **B.IV.5 MAC\_CM\_802\_DATA.indication**
+
+Issued by the CM MAC to indicate reception of data from the downstream channel. Parameters:
+
+- channel\_ID – MAY be implicit if the device supports attachment to a single channel.
+- destination\_address.
+- source\_address.
+- LLC\_pdu.
+- Padding (OPTIONAL) - MAY be present if the LLC PDU was less than 60 bytes and ISO 8802-3 transparency was desired.
+- frame\_check\_sequence.
+- Length.
+
+#### **B.IV.6 MAC\_CM\_DIX\_DATA.indication**
+
+Issued by the CM MAC to indicate reception of data from the downstream channel. Parameters:
+
+- channel\_ID – MAY be implicit if the device supports attachment to a single channel.
+- destination\_address.
+- source\_address.
+- Ethernet type.
+- ethernet\_dix\_pdu.
+- frame\_check\_sequence.
+- Length.
+
+#### **B.IV.7 MAC\_CM\_ATM\_DATA.indication**
+
+Issued by the CM MAC to indicate reception of data on the downstream channel. Parameters:
+
+- channel\_ID – MAY be implicit if the device supports attachment to a single channel.
+- service\_ID.
+- One or more ATM cells – Cells need not be within the same virtual circuit or virtual path.
+- Length.
+
+#### **B.IV.8 MAC\_CM\_DATA.acknowledgment**
+
+Issued by the CM MAC to indicate reception of an acknowledgment on the downstream channel. (An acknowledgment is an information element in an MAP PDU (see B.6.4.1.1). The CMTS MUST include this IE in response to an upstream data transmission that includes an acknowledgment request.) Parameters:
+
+- channel\_ID – The downstream channel on which the acknowledgment was received. May be implicit if the device supports attachment to a single channel.
+- service\_ID.
+- Length.
+
+## Appendix B.V
+
+### Example Burst Profiles
+
+#### B.V.1 Introduction
+
+Table B.V-1 through Table B.V-4 contain example Channel Burst Profiles for various modulation format and symbol rate combinations. The column labeled Column #1 in Table B.V-1 through Table B.V-4 corresponds to the Request burst type. The other columns correspond to the Communication (or Data) burst type. Table B.V-5 contains example Channel Burst Profiles corresponding to Power-Up burst types, or Acquisition burst types (for use on a new channel – or simply for refinement of user-unique parameters).
+
+A burst length of 0 mini-slots in the Channel Profile means that the burst length is variable on that channel for that burst type, and will be assigned by the CMTS for each burst.
+
+A programmable preamble superstring, up to 1024-bits-long, is part of the channel-wide profile or attributes, common to the all burst profiles on the channel (see B.6.3.2.2 and Table B.6-14), but with each burst profile able to specify the start location within this sequence of bits and the length of the preamble (see B.6.3.2.2 and Table B.6-15). The first bit of the Preamble Pattern is designated by the Preamble Value Offset as described in Table B.6-15 and B.6.3.2.2. The first bit of the Preamble Pattern is the first bit into the symbol mapper (see Figure B.4-8), and is  $I_1$  in the first symbol of the burst (see B.4.2.2.2). As an example, per Table B.6-15, for Preamble Offset Value = 100, the 101st bit of the preamble superstring is the first bit into the symbol mapper, and the 102nd bit is the second bit into the mapper, and is mapped to  $Q_1$ , and so on. An example 1024-bit-long preamble superstring is given in B.V.2.
+
+Table B.V-6 contains the frame formats for each of the symbol rates with QPSK modulation for the example Request burst and for three code-word lengths for the Communication bursts, with one code word per burst. Additionally, frame formats are shown for each of the rates with two of the example code-word lengths with four code words per burst. In each format example, the information rate of the burst is calculated and given in the table. For the Request burst, the 6 bytes of "data" are assumed to be the information, and the rest is overhead. In the Communication bursts, the preamble, spacing (guard time), FEC parity, and the example 6 bytes of MAC Header are assumed overhead for the purposes of calculating information rate.
+
+Table B.V-7 is structured the same as Table B.V-6, but with the example formats for 16 QAM modulation.
+
+#### B.V.2 Example preamble sequence
+
+The following is the example 1024-bit preamble sequence for Table B.V-1 through Table B.V-5:
+
+Bits 1 through 128:
+
+1100 1100 1111 0000 1111 1111 1100 0000 1111 0011 1111 0011 0011 0000 0000 1100  
+0011 0000 0011 1111 1111 1100 1100 1100 1111 0000 1111 0011 1111 0011 1100 1100
+
+Bits 129 through 256:
+
+0011 0000 1111 1100 0000 1100 1111 1111 0000 1100 1100 0000 1111 0000 0000 1100  
+0000 0000 1111 1111 1111 0011 0011 0011 1100 0011 1100 1111 1100 1111 0011 0000
+
+Bits 257 through 384:
+
+1100 0011 1111 0000 0011 0011 1111 1100 0011 0011 0000 0011 1100 0000 0011 0000  
+0000 1110 1101 0001 0001 1110 1110 0101 0010 0101 0010 0101 1110 1110 0010 1110
+
+Bits 385 through 512:
+
+0010 1110 1110 0010 0010 1110 1110 1110 1110 1110 0010 0010 0010 1110 1110 0010  
+1110 1110 1110 0010 1110 0010 1110 0010 0010 0010 0010 1110 0010 0010 1110 0010
+
+Bits 513 through 640:
+
+0010 0010 1110 1110 1110 1110 1110 1110 0010 1110 0010 1110 0010 1110 1110 0010  
+0010 1110 1110 0010 1110 1110 1110 0010 1110 1110 0010 1110 0010 0010 1110 0010
+
+Bits 641 through 768:
+
+0010 1110 1110 1110 0010 0010 0010 1110 0010 1110 1110 1110 1110 0010 0010 1110
+
+0010 1110 0010 0010 0010 1110 1110 0010 0010 0010 0010 1110 0010 0010 0010 0010
+
+Bits 769 through 896:
+
+0010 1110 1110 1110 1110 1110 1110 0010 1110 0010 1110 0010 1110 1110 0010 0010
+
+1110 1110 0010 1110 1110 1110 0010 1110 1110 0010 1110 0010 0010 1110 0010 0010
+
+Bits 897 through 1024:
+
+1110 1110 1110 0010 0010 0010 1110 0010 1110 1110 1110 1110 0010 0010 1110 0010
+
+1110 0010 0010 0010 1110 1110 0010 0010 0010 0010 1110 0010 0010 0010 0010 1110
+
+### B.V.3 Example Burst Profiles
+
+See Tables B.V-1 to B.V-7.
+
+**Table B.V-1/J.112 – Example Channel Burst parameter values for QPSK operation at 160, 320, and 640 ksym/s**
+
+| Parameter                             | Config. settings            | #1                     | #2                     | #3                     | #4                     | #5                     |
+|---------------------------------------|-----------------------------|------------------------|------------------------|------------------------|------------------------|------------------------|
+| Modulation                            | QPSK, 16 QAM                | QPSK                   | QPSK                   | QPSK                   | QPSK                   | QPSK                   |
+| Diff Enc                              | On/Off                      | Off                    | Off                    | Off                    | Off                    | Off                    |
+| Symbol Rate                           | 5 configuration settings    | 160, 320 or 640 ksym/s | 160, 320 or 640 ksym/s | 160, 320 or 640 ksym/s | 160, 320 or 640 ksym/s | 160, 320 or 640 ksym/s |
+| Preamble Length                       | 0, 4-1024 bits              | 56 bits                | 64 bits                | 64 bits                | 64 bits                | 64 bits                |
+| Preamble Start Location               | 1024 configuration settings | 15                     | 7                      | 7                      | 7                      | 7                      |
+| Preamble Values                       | 1024 programmable bits      | c)                     | c)                     | c)                     | c)                     | c)                     |
+| FEC On/Off                            | On/Off                      | Off                    | On                     | On                     | On                     | On                     |
+| FEC Code word Information Bytes (k)   | 1 to 255                    | N/A                    | 32                     | 56                     | 64                     | 220                    |
+| FEC Error Correction (T bytes)        | 0 to 10                     | N/A                    | 4                      | 7                      | 8                      | 10                     |
+| Last Code-word Length                 | Fixed or Shortened          | N/A                    | Fixed                  | Fixed                  | Fixed                  | Fixed                  |
+| Scrambler On/Off                      | On/Off                      | On                     | On                     | On                     | On                     | On                     |
+| Scrambler Seed                        | 15 bits <sup>b)</sup>       | Default                | Default                | Default                | Default                | Default                |
+| Burst Length mini-slots <sup>a)</sup> | 0 to 255                    | 3                      | 0                      | 0                      | 0                      | 0                      |
+
+a) A burst length of 0 mini-slots in the Channel Profile means that the burst length is variable on that channel for that burst type.  
+b) 15 bits in a 16-bit field.  
+c) Refer to B.V.2.
+
+**Table B.V-2/J.112 – Example Channel Burst parameter values for  
+QPSK operation at 1.28 and 2.56 Msym/s**
+
+| Parameter                             | Config. settings            | #1                  | #2                  | #3                  | #4                  | #5                  |
+|---------------------------------------|-----------------------------|---------------------|---------------------|---------------------|---------------------|---------------------|
+| Modulation                            | QPSK, 16 QAM                | QPSK                | QPSK                | QPSK                | QPSK                | QPSK                |
+| Diff Enc                              | On/Off                      | Off                 | Off                 | Off                 | Off                 | Off                 |
+| Symbol Rate                           | 5 configuration settings    | 1.28 or 2.56 Msym/s | 1.28 or 2.56 Msym/s | 1.28 or 2.56 Msym/s | 1.28 or 2.56 Msym/s | 1.28 or 2.56 Msym/s |
+| Preamble Length                       | 0,4-1024 bits               | 48 bits             | 96 bits             | 96 bits             | 96 bits             | 96 bits             |
+| Preamble Start Location               | 1024 configuration settings | 19                  | 125                 | 125                 | 125                 | 125                 |
+| Preamble Values                       | 1024 programmable bits      | c)                  | c)                  | c)                  | c)                  | c)                  |
+| FEC On/Off                            | On/Off                      | Off                 | On                  | On                  | On                  | On                  |
+| FEC Code-word Information Bytes (k)   | 1 to 255                    | N/A                 | 40                  | 56                  | 64                  | 220                 |
+| FEC Error Correction (T bytes)        | 0 to 10                     | N/A                 | 4                   | 4                   | 4                   | 10                  |
+| Last Code-word Length                 | Fixed or Shortened          | N/A                 | Fixed               | Fixed               | Fixed               | Fixed               |
+| Scrambler On/Off                      | On/Off                      | On                  | On                  | On                  | On                  | On                  |
+| Scrambler Seed                        | 15 bits <sup>b)</sup>       | Default             | Default             | Default             | Default             | Default             |
+| Burst Length mini-slots <sup>a)</sup> | 0 to 255                    | 4                   | 0                   | 0                   | 0                   | 0                   |
+
+a) A burst length of 0 mini-slots in the Channel Profile means that the burst length is variable on that channel for that burst type.  
+b) 15 bits in a 16-bit field.  
+c) Refer to B.V.2.
+
+**Table B.V-3/J.112 – Example Channel Burst parameter values for  
+16 QAM operation at 160, 320, and 640 ksym/s**
+
+| Parameter                             | Config. settings            | #1                     | #2                     | #3                     | #4                     | #5                     |
+|---------------------------------------|-----------------------------|------------------------|------------------------|------------------------|------------------------|------------------------|
+| Modulation                            | QPSK, 16 QAM                | 16 QAM                 | 16 QAM                 | 16 QAM                 | 16 QAM                 | 16 QAM                 |
+| Diff Enc                              | On/Off                      | Off                    | Off                    | Off                    | Off                    | Off                    |
+| Symbol Rate                           | 5 configuration settings    | 160, 320 or 640 ksym/s | 160, 320 or 640 ksym/s | 160, 320 or 640 ksym/s | 160, 320 or 640 ksym/s | 160, 320 or 640 ksym/s |
+| Preamble Length                       | 0, 4-1024 bits              | 80 bits                | 128 bits               | 128 bits               | 128 bits               | 128 bits               |
+| Preamble Start Location               | 1024 configuration settings | 429                    | 385                    | 385                    | 385                    | 385                    |
+| Preamble Values                       | 1024 programmable bits      | c)                     | c)                     | c)                     | c)                     | c)                     |
+| FEC On/Off                            | On/Off                      | Off                    | On                     | On                     | On                     | On                     |
+| FEC Code-word Information Bytes (k)   | 1 to 255                    | N/A                    | 32                     | 56                     | 64                     | 220                    |
+| FEC Error Correction (T bytes)        | 0 to 10                     | N/A                    | 4                      | 7                      | 8                      | 10                     |
+| Last Code-word Length                 | Fixed or Shortened          | N/A                    | Fixed                  | Fixed                  | Fixed                  | Fixed                  |
+| Scrambler On/Off                      | On/Off                      | On                     | On                     | On                     | On                     | On                     |
+| Scrambler Seed                        | 15 bits <sup>b)</sup>       | Default                | Default                | Default                | Default                | Default                |
+| Burst Length mini-slots <sup>a)</sup> | 0 to 255                    | 2                      | 0                      | 0                      | 0                      | 0                      |
+
+a) A burst length of 0 mini-slots in the Channel Profile means that the burst length is variable on that channel for that burst type.
+
+b) 15 bits in a 16-bit field.
+
+c) Refer to B.V.2.
+
+**Table B.V-4/J.112 – Example Channel Burst parameter values for  
+16 QAM operation at 1.28 and 2.56 Msym/s**
+
+| Parameter                             | Config. settings            | #1                  | #2                  | #3                  | #4                  | #5                  |
+|---------------------------------------|-----------------------------|---------------------|---------------------|---------------------|---------------------|---------------------|
+| Modulation                            | QPSK, 16 QAM                | 16 QAM              | 16 QAM              | 16 QAM              | 16 QAM              | 16 QAM              |
+| Diff Enc                              | On/Off                      | Off                 | Off                 | Off                 | Off                 | Off                 |
+| Symbol Rate                           | 5 configuration settings    | 1.28 or 2.56 Msym/s | 1.28 or 2.56 Msym/s | 1.28 or 2.56 Msym/s | 1.28 or 2.56 Msym/s | 1.28 or 2.56 Msym/s |
+| Preamble Length                       | 0,4-1024 bits               | 144 bits            | 192 bits            | 192 bits            | 192 bits            | 192 bits            |
+| Preamble Start Location               | 1024 configuration settings | 709                 | 621                 | 621                 | 621                 | 621                 |
+| Preamble Values                       | 1024 programmable bits      | c)                  | c)                  | c)                  | c)                  | c)                  |
+| FEC On/Off                            | On/Off                      | Off                 | On                  | On                  | On                  | On                  |
+| FEC Code-word Information Bytes (k)   | 1 to 255                    | N/A                 | 40                  | 56                  | 64                  | 220                 |
+| FEC Error Correction (T bytes)        | 0 to 10                     | N/A                 | 4                   | 4                   | 4                   | 10                  |
+| Last Code-word Length                 | Fixed or Shortened          | N/A                 | Fixed               | Fixed               | Fixed               | Fixed               |
+| Scrambler On/Off                      | On/Off                      | On                  | On                  | On                  | On                  | On                  |
+| Scrambler Seed                        | 15 bits <sup>b)</sup>       | Default             | Default             | Default             | Default             | Default             |
+| Burst Length mini-slots <sup>a)</sup> | 0 to 255                    | 4                   | 0                   | 0                   | 0                   | 0                   |
+
+a) A burst length of 0 mini-slots in the Channel Profile means that the burst length is variable on that channel for that burst type.
+
+b) 15 bits in a 16-bit field.
+
+c) Refer to B.V.2.
+
+**Table B.V-5/J.112 – Example Channel Burst parameter values for power-up and acquisition in a new channel**
+
+| Parameter                             | Config. settings            | #1                     | #2                  | #3                     | #4                  |
+|---------------------------------------|-----------------------------|------------------------|---------------------|------------------------|---------------------|
+| Modulation                            | QPSK, 16 QAM                | QPSK                   | QPSK                | 16 QAM                 | 16 QAM              |
+| Diff Enc                              | On/Off                      | Off                    | Off                 | Off                    | Off                 |
+| Symbol Rate                           | 5 configuration settings    | 160, 320 or 640 ksym/s | 1.28 or 2.56 Msym/s | 160, 320 or 640 ksym/s | 1.28 or 2.56 Msym/s |
+| Preamble Length                       | 0,4-1024 bits               | 1024 bits              | 1024 bits           | 1024 bits              | 1024 bits           |
+| Preamble Start Location               | 1024 configuration settings | 1                      | 1                   | 1                      | 1                   |
+| Preamble Values                       | 1024 programmable bits      | c)                     | c)                  | c)                     | c)                  |
+| FEC On/Off                            | On/Off                      | On                     | On                  | On                     | On                  |
+| FEC Code-word Information Bytes (k)   | 1 to 255                    | 60                     | 60                  | 60                     | 60                  |
+| FEC Error Correction (T bytes)        | 0 to 10                     | 10                     | 10                  | 10                     | 10                  |
+| Last Code-word Length                 | Fixed or Shortened          | Fixed                  | Fixed               | Fixed                  | Fixed               |
+| Scrambler On/Off                      | On/Off                      | On                     | On                  | On                     | On                  |
+| Scrambler Seed                        | 15 bits <sup>b)</sup>       | Default                | Default             | Default                | Default             |
+| Burst Length mini-slots <sup>a)</sup> | 0 to 255                    | 42                     | 53                  | 21                     | 27                  |
+
+a) A burst length of 0 mini-slots in the Channel Profile means that the burst length is variable on that channel for that burst type.
+
+b) 15 bits in a 16-bit field.
+
+c) Refer to B.V.2.
+
+**Table B.V-6/J.112 – Frame format examples with QPSK operation**
+
+| Parameter                                               | 160 ksym/s      | 320 ksym/s      | 640 ksym/s      | 1.28 Msym/s     | 2.56 Msym/s     |
+|---------------------------------------------------------|-----------------|-----------------|-----------------|-----------------|-----------------|
+| <b>Request Burst</b>                                    |                 |                 |                 |                 |                 |
+| Spacing symbols (bytes)<br>i.e. (guard time symbols –1) | 8 (2)           | 8 (2)           | 8 (2)           | 16 (4)          | 16 (4)          |
+| Data symbols (bytes)                                    | 24 (6)          | 24 (6)          | 24 (6)          | 24 (6)          | 24 (6)          |
+| Preamble symbols (bytes)                                | 28 (7)          | 28 (7)          | 28 (7)          | 24 (6)          | 24 (6)          |
+| Total symbols (bytes)                                   | 60 (15)         | 60 (15)         | 60 (15)         | 64 (16)         | 64 (16)         |
+| Total burst duration<br>(mini-slots)                    | 3               | 3               | 3               | 4               | 4               |
+| Total burst duration<br>(microseconds)                  | 375             | 187.5           | 93.75           | 50              | 25              |
+| Information rate<br>(6 bytes per burst)                 | 128 kbit/s      | 256 kbit/s      | 512 kbit/s      | 960 kbit/s      | 1.92 Mbit/s     |
+| <b>Communication Burst</b>                              |                 |                 |                 |                 |                 |
+| Code words/burst                                        | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> |
+| Errors corrected per code word                          | 4               | 4               | 4               | 4               | 4               |
+| Spacing symbols (bytes)<br>i.e. (guard time symbols –1) | 8 (2)           | 8 (2)           | 8 (2)           | 16 (4)          | 16 (4)          |
+| Data symbols (bytes)                                    | 128 (32)        | 128 (32)        | 128 (32)        | 160 (40)        | 160 (40)        |
+| Parity symbols (bytes)                                  | 32 (8)          | 32 (8)          | 32 (8)          | 32 (8)          | 32 (8)          |
+| Preamble symbols (bytes)                                | 32 (8)          | 32 (8)          | 32 (8)          | 48 (12)         | 48 (12)         |
+| Total symbols (bytes)                                   | 200 (50)        | 200 (50)        | 200 (50)        | 256 (64)        | 256 (64)        |
+| Total burst duration (mini-slots)                       | 2 + 8 = 10      | 2 + 8 = 10      | 2 + 8 = 10      | 4 + 12 = 16     | 4 + 12 = 16     |
+| Total burst duration<br>(microseconds)                  | 1250            | 625             | 312.5           | 200             | 100             |
+| Information rate<br>(excluding MAC Header)              | 166.4 kbit/s    | 332.8 kbit/s    | 665.6 kbit/s    | 1.360 Mbit/s    | 2.720 Mbit/s    |
+| <b>Communication Burst</b>                              |                 |                 |                 |                 |                 |
+| Code words/burst                                        | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> |
+| Errors corrected per code word                          | 8               | 8               | 8               | 4               | 4               |
+| Spacing symbols (bytes)<br>i.e. (guard time symbols –1) | 8 (2)           | 8 (2)           | 8 (2)           | 16 (4)          | 16 (4)          |
+| Data symbols (bytes)                                    | 256 (64)        | 256 (64)        | 256 (64)        | 256 (64)        | 256 (64)        |
+| Parity symbols (bytes)                                  | 64 (16)         | 64 (16)         | 64 (16)         | 32 (8)          | 32 (8)          |
+| Preamble symbols (bytes)                                | 32 (8)          | 32 (8)          | 32 (8)          | 48 (12)         | 48 (12)         |
+| Total symbols (bytes)                                   | 360 (90)        | 360 (90)        | 360 (90)        | 352 (88)        | 352 (88)        |
+| Total burst duration (mini-slots)                       | 2 + 16 = 18     | 2 + 16 = 18     | 2 + 16 = 18     | 4 + 18 = 22     | 4 + 18 = 22     |
+| Total burst duration<br>(microseconds)                  | 2250            | 1125            | 562.5           | 275             | 137.5           |
+| Information rate<br>(excluding MAC Header)              | 206.2 kbit/s    | 412.4 kbit/s    | 824.9 kbit/s    | 1.687 Mbit/s    | 3.375 Mbit/s    |
+| <b>Communication Burst</b>                              |                 |                 |                 |                 |                 |
+| Code words/burst                                        | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> |
+| Errors corrected per code word                          | 10              | 10              | 10              | 10              | 10              |
+
+**Table B.V-6/J.112 – Frame format examples with QPSK operation (end)**
+
+| Parameter                                               | 160 ksym/s       | 320 ksym/s       | 640 ksym/s       | 1.28 Msym/s      | 2.56 Msym/s      |
+|---------------------------------------------------------|------------------|------------------|------------------|------------------|------------------|
+| Spacing symbols (bytes)<br>i.e. (guard time symbols –1) | 8 (2)            | 8 (2)            | 8 (2)            | 16 (4)           | 16 (4)           |
+| Data symbols (bytes)                                    | 880 (220)        | 880 (220)        | 880 (220)        | 880 (220)        | 880 (220)        |
+| Parity symbols (bytes)                                  | 80 (20)          | 80 (20)          | 80 (20)          | 80 (20)          | 80 (20)          |
+| Preamble symbols (bytes)                                | 32 (8)           | 32 (8)           | 32 (8)           | 48 (12)          | 48 (12)          |
+| Total symbols (bytes)                                   | 1000 (250)       | 1000 (250)       | 1000 (250)       | 1024 (256)       | 1024 (256)       |
+| Total burst duration (mini-slots)                       | 2 + 48 = 50      | 2 + 48 = 50      | 2 + 48 = 50      | 4 + 60 = 64      | 4 + 60 = 64      |
+| Total burst duration (microseconds)                     | 6250             | 3125             | 1562.5           | 800              | 400              |
+| Information rate<br>(excluding MAC Header)              | 273.9 kbit/s     | 547.8 kbit/s     | 1.096 Mbit/s     | 2.140 Mbit/s     | 4.280 Mbit/s     |
+| <b>Communication Burst</b><br>Code words/burst          | 4 <sup>a)</sup>  | 4 <sup>a)</sup>  | 4 <sup>a)</sup>  | 4 <sup>a)</sup>  | 4 <sup>a)</sup>  |
+| Errors corrected per code word                          | 8                | 8                | 8                | 4                | 4                |
+| Spacing symbols (bytes)<br>i.e. (guard time symbols –1) | 8 (2)            | 8 (2)            | 8 (2)            | 16 (4)           | 16 (4)           |
+| Data symbols (bytes)                                    | 1024 (256)       | 1024 (256)       | 1024 (256)       | 1024 (256)       | 1024 (256)       |
+| Parity symbols (bytes)                                  | 256 (64)         | 256 (64)         | 256 (64)         | 128 (32)         | 128 (32)         |
+| Preamble symbols (bytes)                                | 32 (8)           | 32 (8)           | 32 (8)           | 48 (12)          | 48 (12)          |
+| Total symbols (bytes)                                   | 1320 (330)       | 1320 (330)       | 1320 (330)       | 1216 (304)       | 1216 (304)       |
+| Total burst duration (mini-slots)                       | 2 + 16 × 4 = 66  | 2 + 16 × 4 = 66  | 2 + 16 × 4 = 66  | 4 + 18 × 4 = 76  | 4 + 18 × 4 = 76  |
+| Total burst duration (microseconds)                     | 8250             | 4125             | 2062.5           | 950              | 475              |
+| Information rate<br>(excluding MAC Header)              | 242.4 kbit/s     | 484.8 kbit/s     | 969.7 kbit/s     | 2.105 Mbit/s     | 4.211 Mbit/s     |
+| <b>Communication Burst</b><br>Code words/burst          | 4 <sup>a)</sup>  | 4 <sup>a)</sup>  | 4 <sup>a)</sup>  | 4 <sup>a)</sup>  | 1 <sup>a)</sup>  |
+| Errors corrected per code word                          | 10               | 10               | 10               | 10               | 10               |
+| Spacing symbols (bytes)<br>i.e. (guard time symbols –1) | 8 (2)            | 8 (2)            | 8 (2)            | 16 (4)           | 16 (4)           |
+| Data symbols (bytes)                                    | 3520 (880)       | 3520 (880)       | 3520 (880)       | 3520 (880)       | 3520 (880)       |
+| Parity symbols (bytes)                                  | 320 (80)         | 320 (80)         | 320 (80)         | 320 (80)         | 320 (80)         |
+| Preamble symbols (bytes)                                | 32 (8)           | 32 (8)           | 32 (8)           | 48 (12)          | 48 (12)          |
+| Total symbols (bytes)                                   | 3880 (970)       | 3880 (970)       | 3880 (970)       | 3904 (976)       | 3904 (976)       |
+| Total burst duration (mini-slots)                       | 2 + 48 × 4 = 194 | 2 + 48 × 4 = 194 | 2 + 48 × 4 = 194 | 4 + 60 × 4 = 244 | 4 + 60 × 4 = 244 |
+| Total burst duration (microseconds)                     | 24 250           | 12 125           | 6062.5           | 3050             | 1525             |
+| Information rate<br>(excluding MAC Header)              | 288.3 kbit/s     | 576.7 kbit/s     | 1.153 Mbit/s     | 2.292 Mbit/s     | 4.585 Mbit/s     |
+
+<sup>a)</sup> The numbers in the table are given for four code words per burst, but more or fewer code words can be used, with the same data and parity lengths as given in the table.
+
+**Table B.V-7/J.112 – Frame format examples with 16 QAM operation**
+
+| Parameter                                               | 160 ksym/s      | 320 ksym/s      | 640 ksym/s      | 1.28 Msym/s     | 2.56 Msym/s     |
+|---------------------------------------------------------|-----------------|-----------------|-----------------|-----------------|-----------------|
+| <b>Request Burst</b>                                    |                 |                 |                 |                 |                 |
+| Spacing symbols (bytes)<br>i.e. (guard time symbols –1) | 8 (4)           | 8 (4)           | 8 (4)           | 16 (8)          | 16 (8)          |
+| Data symbols (bytes)                                    | 12 (6)          | 12 (6)          | 12 (6)          | 12 (6)          | 12 (6)          |
+| Preamble symbols (bytes)                                | 20 (10)         | 20 (10)         | 20 (10)         | 36 (18)         | 36 (18)         |
+| Total symbols (bytes)                                   | 40 (20)         | 40 (20)         | 40 (20)         | 64 (32)         | 64 (32)         |
+| Total burst duration (mini-slots)                       | 2               | 2               | 2               | 4               | 4               |
+| Total burst duration (microseconds)                     | 250             | 125             | 62.5            | 50              | 25              |
+| Information rate<br>(6 bytes per burst)                 | 192 kbit/s      | 384 kbit/s      | 768 kbit/s      | 960 kbit/s      | 1.920 Mbit/s    |
+| <b>Communication Burst</b>                              |                 |                 |                 |                 |                 |
+| Code words/burst                                        | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> |
+| Errors corrected per code word                          | 4               | 4               | 4               | 4               | 4               |
+| Spacing symbols (bytes)<br>i.e. (guard time symbols –1) | 8 (4)           | 8 (4)           | 8 (4)           | 16 (8)          | 16 (8)          |
+| Data symbols (bytes)                                    | 64 (32)         | 64 (32)         | 64 (32)         | 80 (40)         | 80 (40)         |
+| Parity symbols (bytes)                                  | 16 (8)          | 16 (8)          | 16 (8)          | 16 (8)          | 16 (8)          |
+| Preamble symbols (bytes)                                | 32 (16)         | 32 (16)         | 32 (16)         | 48 (24)         | 48 (24)         |
+| Total symbols (bytes)                                   | 120 (60)        | 120 (60)        | 120 (60)        | 160 (80)        | 160 (80)        |
+| Total burst duration (mini-slots)                       | 2 + 4 = 6       | 2 + 4 = 6       | 2 + 4 = 6       | 4 + 6 = 10      | 4 + 6 = 10      |
+| Total burst duration (microseconds)                     | 750             | 375             | 187.5           | 125             | 62.5            |
+| Information rate<br>(excluding MAC Header)              | 277.3 kbit/s    | 554.7 kbit/s    | 1.109 Mbit/s    | 2.176 Mbit/s    | 4.352 Mbit/s    |
+| <b>Communication Burst</b>                              |                 |                 |                 |                 |                 |
+| Code words/burst                                        | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> |
+| Errors corrected per code word                          | 7               | 7               | 7               | 4               | 4               |
+| Spacing symbols (bytes)<br>i.e. (guard time symbols –1) | 8 (4)           | 8 (4)?          | 8 (4)           | 16 (8)          | 16 (8)          |
+| Data symbols (bytes)                                    | 128 (64)        | 128 (64)        | 128 (64)        | 128 (64)        | 128 (64)        |
+| Parity symbols (bytes)                                  | 32 (16)         | 32 (16)         | 32 (16)         | 16 (8)          | 16 (8)          |
+| Preamble symbols (bytes)                                | 32 (16)         | 32 (16)         | 32 (16)         | 48 (24)         | 48 (24)         |
+| Total symbols (bytes)                                   | 200 (100)       | 200 (100)       | 200 (100)       | 208 (104)       | 208 (104)       |
+| Total burst duration (mini-slots)                       | 2 + 8 = 10      | 2 + 8 = 10      | 2 + 8 = 10      | 4 + 9 = 13      | 4 + 9 = 13      |
+| Total burst duration (microseconds)                     | 1250            | 625             | 312.5           | 162.5           | 81.25           |
+| Information rate<br>(excluding MAC Header)              | 371.2 kbit/s    | 742.4 kbit/s    | 1.455 Mbit/s    | 2.855 Mbit/s    | 5.711 Mbit/s    |
+| <b>Communication Burst</b>                              |                 |                 |                 |                 |                 |
+| Code words/burst                                        | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> | 1 <sup>a)</sup> |
+| Errors corrected per code word                          | 10              | 10              | 10              | 10              | 10              |
+
+**Table B.V-7/J.112 – Frame format examples with 16 QAM operation (end)**
+
+| Parameter                                               | 160 ksym/s      | 320 ksym/s      | 640 ksym/s      | 1.28 Msym/s      | 2.56 Msym/s      |
+|---------------------------------------------------------|-----------------|-----------------|-----------------|------------------|------------------|
+| Spacing symbols (bytes)<br>i.e. (guard time symbols –1) | 8 (4)           | 8 (4)           | 8 (4)           | 16 (8)           | 16 (8)           |
+| Data symbols (bytes)                                    | 440 (220)       | 440 (220)       | 440 (220)       | 440 (220)        | 440 (220)        |
+| Parity symbols (bytes)                                  | 40 (20)         | 40 (20)         | 40 (20)         | 40 (20)          | 40 (20)          |
+| Preamble symbols (bytes)                                | 32 (16)         | 32 (16)         | 32 (16)         | 48 (24)          | 48 (24)          |
+| Total symbols (bytes)                                   | 520 (260)       | 520 (260)       | 520 (260)       | 544 (272)        | 544 (272)        |
+| Total burst duration (mini-slots)                       | 2 + 24 = 26     | 2 + 24 = 26     | 2 + 24 = 26     | 4 + 30 = 34      | 4 + 30 = 34      |
+| Total burst duration (microseconds)                     | 3250            | 1625            | 812.5           | 425              | 212.5            |
+| Information rate<br>(excluding MAC Header)              | 526.8 kbit/s    | 1.054 Mbit/s    | 2.107 Mbit/s    | 4.028 Mbit/s     | 8.056 Mbit/s     |
+| <b>Communication Burst</b>                              |                 |                 |                 |                  |                  |
+| Code words/burst                                        | 4 <sup>a)</sup> | 4 <sup>a)</sup> | 4 <sup>a)</sup> | 4 <sup>a)</sup>  | 4 <sup>a)</sup>  |
+| Errors corrected per code word                          | 7               | 7               | 7               | 4                | 4                |
+| Spacing symbols (bytes)<br>i.e. (guard time symbols –1) | 8 (4)           | 8 (4)           | 8 (4)           | 16 (8)           | 16 (8)           |
+| Data symbols (bytes)                                    | 512 (256)       | 512 (256)       | 512 (256)       | 512 (256)        | 512 (256)        |
+| Parity symbols (bytes)                                  | 128 (64)        | 128 (64)        | 128 (64)        | 64 (32)          | 64 (32)          |
+| Preamble symbols (bytes)                                | 32 (16)         | 32 (16)         | 32 (16)         | 48 (24)          | 48 (24)          |
+| Total symbols (bytes)                                   | 680 (340)       | 680 (340)       | 680 (340)       | 640 (320)        | 640 (320)        |
+| Total burst duration (mini-slots)                       | 2 + 8 × 4 = 34  | 2 + 8 × 4 = 34  | 2 + 8 × 4 = 34  | 4 + 9 × 4 = 40   | 4 + 9 × 4 = 40   |
+| Total burst duration (microseconds)                     | 4250            | 2125            | 1062.5          | 500              | 250              |
+| Information rate<br>(excluding MAC Header)              | 470.6 kbit/s    | 941.2 kbit/s    | 1.882 Mbit/s    | 4.000 Mbit/s     | 8.000 Mbit/s     |
+| <b>Communication Burst</b>                              |                 |                 |                 |                  |                  |
+| Code words/burst                                        | 4 <sup>a)</sup> | 4 <sup>a)</sup> | 4 <sup>a)</sup> | 4 <sup>a)</sup>  | 4 <sup>a)</sup>  |
+| Errors corrected per code word                          | 10              | 10              | 10              | 10               | 10               |
+| Spacing symbols (bytes)<br>i.e. (guard time symbols –1) | 8 (4)           | 8 (4)           | 8 (4)           | 16 (8)           | 16 (8)           |
+| Data symbols (bytes)                                    | 1760 (880)      | 1760 (880)      | 1760 (880)      | 1760 (880)       | 1760 (880)       |
+| Parity symbols (bytes)                                  | 160 (80)        | 160 (80)        | 160 (80)        | 160 (80)         | 160 (80)         |
+| Preamble symbols (bytes)                                | 32 (16)         | 32 (16)         | 32 (16)         | 48 (24)          | 48 (24)          |
+| Total symbols (bytes)                                   | 1960 (980)      | 1960 (980)      | 1960 (980)      | 1984 (992)       | 1984 (992)       |
+| Total burst duration (mini-slots)                       | 2 + 24 × 4 = 98 | 2 + 24 × 4 = 98 | 2 + 24 × 4 = 98 | 4 + 30 × 4 = 124 | 4 + 30 × 4 = 124 |
+| Total burst duration (microseconds)                     | 12 250          | 6125            | 3062.5          | 1550             | 775              |
+| Information rate<br>(excluding MAC Header)              | 570.8 kbit/s    | 1.142 Mbit/s    | 2.283 Mbit/s    | 4.511 Mbit/s     | 9.022 Mbit/s     |
+
+a) The numbers in the table are given for four code words per burst, but more or fewer code words can be used, with the same data and parity lengths as given in the table.
+
+## Appendix B.VI
+
+### Upstream modulation rates
+
+#### B.VI.1 Introduction
+
+The sources of ingress are not randomly distributed throughout the upstream cable network spectrum, but are grouped in frequency bands accordance with the International Radio Regulations, which is an international treaty subscribed to by most countries of the world. In some bands, higher powers are used, so ingress is more likely to be found there. The pattern of allocations can be readily recognized by examination of the upstream cable network band with a spectrum analyzer.
+
+The upstream modulation rates and flexibility in selecting upstream carrier frequencies defined in this appendix permit operators to position carriers in those portions of the upstream cable network spectrum which are less prone to narrowband ingress.
+
+#### B.VI.2 Sources of narrowband ingress
+
+Radio transmitters in the High-Frequency (HF) portion of the radio spectrum (3 to 30 MHz) are the major sources of narrowband ingress. The transmitters that can affect upstream cable network paths may be local, domestic or in other countries.
+
+##### B.VI.2.1 HF Propagation
+
+HF propagation is largely influenced by bending of radio waves in the ionosphere, which is a region between about 60 and 200 miles above the earth, so propagation distances can be very large. The bending is caused by ionization of free electrons by ultra-violet rays from the sun. There are several reflecting layers at various heights with differing characteristics, so the maximum usable frequency and distance reached depend on the time of day and solar activity.
+
+**Diurnal Variation** – During local daytime, the higher frequencies are propagated over long distances and the lower frequencies are absorbed. During local night-time, the lower frequencies are propagated over distances which are not quite so large, and the higher frequencies experience diminished or no propagation.
+
+**Solar Cycle** – Ionization is at its greatest during the peak of the 11-year sunspot cycle. At the largest sunspot peaks, strong distant signals can be heard across the HF band at most times of the day. At sunspot minima, long-distance propagation can be rare above about 15 MHz. Note that the cycle is currently at a minimum, so ingress is likely to affect cable systems on an increasing basis and at higher frequencies over the next 5 to 6 years.
+
+##### B.VI.2.2 Users of the HF radio spectrum
+
+The main users of the HF radio spectrum are:
+
+- Broadcasting;
+- Maritime mobile;
+- Aeronautical mobile;
+- Aeronautical navigation;
+- Fixed (i.e. point-to-point);
+- Standard frequency and time signals;
+- Amateur;
+- Citizens Band (CB).
+
+The service of greatest concern for ingress is the Broadcasting Service. The Amateur and Citizens Band services are also of concern.
+
+### B.VI.2.3 Broadcasting
+
+The main ingress signals seen on typical cable networks are short-wave Broadcasting signals. The Broadcasting service is designed to provide very high field strengths in target markets so that the public can receive clear signals with simple receivers. Thus the service generally has these characteristics:
+
+- amplitude-modulated signals;
+- very high transmitter powers;
+- high-gain, directive antenna arrays;
+- simultaneous transmission on multiple frequencies in different parts of the HF spectrum, to combat HF propagation variability;
+- very large field strengths over a wide geographic area, affecting entire cable systems.
+
+The frequencies allocated to the Broadcasting Service on a world-wide basis are shown in Table B.VI-1.
+
+**Table B.VI-1/J.112 – Broadcasting allocations between 5 and 42 MHz**
+
+| Frequency, kHz |        |
+|----------------|--------|
+| From           | To     |
+| 5 950          | 6 200  |
+| 7 100          | 7 300  |
+| 9 500          | 9 900  |
+| 11 650         | 12 050 |
+| 13 600         | 13 800 |
+| 15 100         | 15 600 |
+| 17 550         | 17 900 |
+| 21 450         | 21 850 |
+| 25 670         | 26 100 |
+
+NOTE – Although 7100-7300 kHz is not allocated to Broadcasting in ITU Region 2 (the Americas), strong signals reach the USA and Canada from the other ITU Regions.
+
+### B.VI.2.4 Amateur and CB
+
+The Amateur Service is of concern, but for different reasons. Amateur transmitters operate at far lower powers than the Broadcasting Service, but are located in residential neighborhoods close to the cable plant, so they can represent potential localized sources of ingress in different bands across the HF spectrum. Radiation from the upstream cable plant may also cause interference into amateur receivers.
+
+The Citizens Band Service operates at powers which are very much lower and are less likely to be sources of ingress. However, CB receivers may be capable of picking up interference from cable plant radiation.
+
+The allocations in the USA and Canada for the Amateur and Citizens Band Services between 5 and 42 MHz are indicated in Table B.VI-2.
+
+### B.VI.2.5 Other services
+
+The other services in the HF spectrum operate at powers which are lower than Broadcasting, and are usually not located in residential areas, so they are less likely to be of concern. In the low VHF region between 30 and 42 MHz, there may be a localized effect from high-power paging in the vicinity of 35 MHz.
+
+**Table B.VI-2/J.112 – Amateur and Citizens Band allocations between 5 and 42 MHz**
+
+| Frequency, kHz |        |
+|----------------|--------|
+| From           | To     |
+| 7 000          | 7 300  |
+| 10 100         | 10 150 |
+| 14 000         | 14 350 |
+| 18 068         | 18 168 |
+| 21 000         | 21 450 |
+| 24 890         | 24 990 |
+| 26 960         | 27 240 |
+| 28 000         | 29 700 |
+
+### B.VI.3 Fitting data carriers within the ingress gaps
+
+The range of modulation rates and the flexibility in setting upstream carrier frequencies defined in this appendix permit operators to fit data-over-cable carriers in the gaps between the short-wave Broadcasting bands, to avoid this significant source of ingress. They also permit operators to avoid the Amateur and Citizens Band bands as well.
+
+Table B.VI-3 illustrates the quantity of data carriers that can be derived in the gaps between the Broadcasting allocations at the channel widths specified in this appendix, and the resulting utilization of the available spectrum. Table B.VI-4 shows a similar illustration for the gaps between the Broadcasting, Amateur and CB allocations. A conservative upper limit of 40 MHz is used.
+
+**Table B.VI-3/J.112 – Data carriers in the gaps between broadcasting bands**
+
+| Non-broadcast spectrum, kHz |        |        | Data carrier width, kHz |        |        |        |        |
+|-----------------------------|--------|--------|-------------------------|--------|--------|--------|--------|
+|                             |        |        | 200                     | 400    | 800    | 1600   | 3200   |
+| From                        | To     | Gap    | Data carriers available |        |        |        |        |
+| 5 000                       | 5 950  | 950    | 4                       | 2      | 1      | 0      | 0      |
+| 6 200                       | 7 100  | 900    | 4                       | 2      | 1      | 0      | 0      |
+| 7 300                       | 9 500  | 2 200  | 11                      | 5      | 2      | 1      | 0      |
+| 9 900                       | 11 650 | 1 750  | 8                       | 4      | 2      | 1      | 0      |
+| 12 050                      | 13 600 | 1 550  | 7                       | 3      | 1      | 0      | 0      |
+| 13 800                      | 15 100 | 1 300  | 6                       | 3      | 1      | 0      | 0      |
+| 15 600                      | 17 550 | 1 950  | 9                       | 4      | 2      | 1      | 0      |
+| 17 900                      | 21 450 | 3 550  | 17                      | 8      | 4      | 2      | 1      |
+| 21 850                      | 25 670 | 3 820  | 19                      | 9      | 4      | 2      | 1      |
+| 26 100                      | 40 000 | 13 900 | 69                      | 34     | 17     | 8      | 4      |
+| Least gap, kHz              |        | 900    |                         |        |        |        |        |
+| Total carriers              |        |        | 154                     | 74     | 35     | 15     | 6      |
+| Total bandwidth, kHz        |        | 31 870 | 30 800                  | 29 600 | 28 000 | 24 000 | 19 200 |
+| Utilization, %              |        |        | 97                      | 93     | 88     | 75     | 60     |
+
+**Table B.VI-4/J.112 – Data carriers in the gaps between Broadcasting, Amateur and CB bands**
+
+| Spectrum other than Broadcast,<br>Amateur, CB, kHz |        |        | Data carrier width, kHz |        |        |        |      |
+|----------------------------------------------------|--------|--------|-------------------------|--------|--------|--------|------|
+|                                                    |        |        | 200                     | 400    | 800    | 1600   | 3200 |
+| From                                               | To     | Gap    | Data carriers available |        |        |        |      |
+| 5 000                                              | 5 950  | 950    | 4                       | 2      | 1      | 0      | 0    |
+| 6 200                                              | 7 000  | 800    | 4                       | 2      | 1      | 0      | 0    |
+| 7 300                                              | 9 500  | 2 200  | 11                      | 5      | 2      | 1      | 0    |
+| 9 900                                              | 10 100 | 200    | 1                       | 0      | 0      | 0      | 0    |
+| 10 150                                             | 11 650 | 1 500  | 7                       | 3      | 1      | 0      | 0    |
+| 12 050                                             | 13 600 | 1 550  | 7                       | 3      | 1      | 0      | 0    |
+| 13 800                                             | 14 000 | 200    | 1                       | 0      | 0      | 0      | 0    |
+| 14 350                                             | 15 100 | 750    | 3                       | 1      | 0      | 0      | 0    |
+| 15 600                                             | 17 550 | 1 950  | 9                       | 4      | 2      | 1      | 0    |
+| 17 900                                             | 18 068 | 168    | 0                       | 0      | 0      | 0      | 0    |
+| 18 168                                             | 21 000 | 2 832  | 14                      | 7      | 3      | 1      | 0    |
+| 21 850                                             | 24 890 | 3 040  | 15                      | 7      | 3      | 1      | 0    |
+| 24 990                                             | 25 670 | 680    | 3                       | 1      | 0      | 0      | 0    |
+| 26 100                                             | 26 960 | 860    | 4                       | 2      | 1      | 0      | 0    |
+| 27 410                                             | 28 000 | 590    | 2                       | 1      | 0      | 0      | 0    |
+| 29 700                                             | 40 000 | 10 300 | 51                      | 25     | 12     | 6      | 3    |
+| Least gap, kHz                                     |        | 168    |                         |        |        |        |      |
+| Total carriers                                     |        |        | 136                     | 63     | 27     | 10     | 3    |
+| Total bandwidth, kHz                               |        | 28 750 | 27 200                  | 25 200 | 21 600 | 16 000 | 9600 |
+| Utilization, %                                     |        |        | 95                      | 88     | 76     | 56     | 34   |
+
+## Appendix B.VII
+
+### Example: Multiple upstream channels
+
+This appendix presents an example of several upstream channels served by a single downstream channel. This is meant to illustrate one topology and one implementation of that topology.
+
+Suppose one downstream channel is used in conjunction with four upstream channels as shown in Figure B.VII-1. In this case, the four upstream channels are separate fibers serving four geographical communities of modems.
+
+![Diagram of a network topology showing one CMTS connected to four CMs via separate upstream channels and a shared downstream channel.](0fec4b5689fcc9aa96a87f0c1bdaf200_img.jpg)
+
+The diagram illustrates a network topology. At the top center is a box labeled 'CMTS'. Below it are four boxes, each labeled 'CM', arranged in a 2x2 grid. A central vertical line descends from the CMTS. Four curved arrows originate from each CM box and point towards the CMTS box, representing four separate upstream channels. Two horizontal arrows point from the central vertical line to the left CM and the right CM, representing a shared downstream channel. At the bottom right of the diagram, the text 'T0905250-97/d109' is present.
+
+Diagram of a network topology showing one CMTS connected to four CMs via separate upstream channels and a shared downstream channel.
+
+Figure B.VII-1/J.112 – One downstream and four upstream channels
+
+In this topology, the CMTS transmits four Upstream Channel Descriptors (UCDs) and four MAPs. Unfortunately, each CM cannot determine to which upstream channel it is attached, because there is no way to convey the geographical information on the shared downstream channel. The CM must assume (at least at initialization) that the UCD and MAP apply to the channel to which it is attached. The CM chooses an Initial Maintenance opportunity on any of the channels and transmits a Ranging Request. The CMTS will receive the request and will redirect the CM to the appropriate upstream channel identifier. From then on, the CM will be using the MAP that is appropriate to the fiber branch to which it is connected.
+
+A number of constraints are imposed by this topology:
+
+- All of the upstream channels must operate at the same frequency. Since the CM is choosing a channel descriptor at random, it would be transmitting on the wrong frequency if it chose the UCD that applied to a different fiber path.
+- All of the upstream channels must operate at the same symbol rate. If not, the CMTS would be unable to demodulate the Ranging Request if transmitted at the wrong symbol rate for the particular channel.
+- All Initial Maintenance opportunities across all fiber branches must be aligned. When the CM randomly chooses a MAP to use, the CMTS must be prepared to receive a Ranging Request at that time.
+- All Initial Maintenance opportunities must use the same burst characteristics so that the CMTS can demodulate the Ranging Request.
+
+Note that only the initialization intervals must be aligned. Once the CM is assigned its proper channel ID, its activities need only be aligned with other users of its fiber branch. Ordinary data transmission and requests for bandwidth may occur independently across the four upstream channels.
+
+## Appendix B.VIII
+
+### The data-over-cable spanning tree protocol
+
+Subclause B.3.1.2.1 requires the use of the spanning tree protocol on CMs that are intended for commercial use and on bridging CMTSs. This appendix describes how the 802.1d spanning tree protocol is adapted to work for data over cable systems.
+
+#### B.VIII.1 Background
+
+A spanning tree protocol is frequently employed in a bridged network in order to deactivate redundant network connections, i.e. to reduce an arbitrary network mesh topology to an active topology that is a rooted tree that spans all of the network segments. The spanning tree algorithm and protocol should not be confused with the data-forwarding function itself; data forwarding may follow transparent learning bridge rules, or may employ any of several other mechanisms. By deactivating redundant connections, the spanning tree protocol eliminates topological loops, which would otherwise cause data packets to be forwarded forever for many kinds of forwarding devices.
+
+A standard spanning tree protocol [IEEE 802.1d] is employed in most bridged local area networks. This protocol was intended for private LAN use and requires some modification for cable data use.
+
+#### B.VIII.2 Public Spanning Tree
+
+To use a spanning tree protocol in a public-access network such as data-over-cable, several modifications are needed to the basic IEEE 802.1d process. Primarily, the public spanning tree must be isolated from any private spanning tree networks to which it is connected. This is to protect both the public cable network and any attached private networks. Figure B.VIII-1 illustrates the general topology.
+
+![Diagram of a spanning tree topology for data-over-cable. A central CMTS is connected to a horizontal bus. Three Cable Modems are connected to this bus. The top Cable Modem is connected to a cloud labeled 'Bridged Private Network'. The bottom two Cable Modems are connected to a single cloud labeled 'Bridged Private Network'. A small text label 'T0906680-98/d110' is present in the bottom right corner of the diagram area.](2aea72b147efb82b46a78aaea9f1ac22_img.jpg)
+
+T0906680-98/d110
+
+Diagram of a spanning tree topology for data-over-cable. A central CMTS is connected to a horizontal bus. Three Cable Modems are connected to this bus. The top Cable Modem is connected to a cloud labeled 'Bridged Private Network'. The bottom two Cable Modems are connected to a single cloud labeled 'Bridged Private Network'. A small text label 'T0906680-98/d110' is present in the bottom right corner of the diagram area.
+
+Figure B.VIII-1/J.112 – Spanning tree topology
+
+The task for the public spanning tree protocol, with reference to Figure B.VIII-1, is to:
+
+- Isolate the private bridged networks from each other. If the two private networks merge spanning trees, then each is subject to instabilities in the other's network. Also, the combined tree may exceed the maximum allowable bridging diameter.
+- Isolate the public network from the private networks' spanning trees. The public network must not be subject to instabilities induced by customers' networks; nor should it change the spanning tree characteristics of the customers' networks.
+- Disable one of the two redundant links into the cable network, so as to prevent forwarding loops. This should occur at the cable modem, rather than at an arbitrary bridge within the customer's network.
+
+The spanning tree protocol must also serve the topology illustrated in Figure B.VIII-2:
+
+In Figure B.VIII-2, in normal operation the spanning tree protocol should deactivate a link at one of the two cable modems. It should not divert traffic across the private network. Note that in some circumstances, such as deactivation of Link-X, spanning tree *will* divert traffic onto the private network (although limits on learned MAC addresses will probably throttle most transit traffic). If this diversion is undesirable, then it must be prevented by means external to spanning tree; for example, by using routers.
+
+![Diagram illustrating a network topology for spanning tree across CMTSs. A 'Switched/Bridged Headend Network' is connected via 'Link-X' to two 'CMTS (bridge)' units. Each CMTS is connected to a 'Cable Modem', which in turn is connected to a 'Bridged Private Network'. The diagram shows two parallel paths from the headend network through the CMTSs and cable modems into the private network. A small text 'T0906690-98/d111' is visible in the bottom right corner of the diagram area.](6caa056e54d81c8403fe884e3c29fa66_img.jpg)
+
+Diagram illustrating a network topology for spanning tree across CMTSs. A 'Switched/Bridged Headend Network' is connected via 'Link-X' to two 'CMTS (bridge)' units. Each CMTS is connected to a 'Cable Modem', which in turn is connected to a 'Bridged Private Network'. The diagram shows two parallel paths from the headend network through the CMTSs and cable modems into the private network. A small text 'T0906690-98/d111' is visible in the bottom right corner of the diagram area.
+
+**Figure B.VIII-2/J.112 – Spanning tree across CMTSs**
+
+### B.VIII.3 Public spanning tree protocol details
+
+The Data over Cable Spanning Tree algorithm and protocol is identical to that defined in [IEEE 802.1d], with the following exceptions:
+
+- When transmitting Configuration Bridge Protocol Data Units (BPDUs), the Data over Cable Spanning Tree Multicast Address 01-E0-2F-00-00-03 is used rather than that defined in IEEE 802.1d. These BPDUs will be forwarded rather than recalculated by ordinary IEEE 802.1d bridges.
+- When transmitting Configuration BPDUs, the SNAP header AA-AA-03-00-E0-2F-73-74 is used rather than the LLC 42-42-03 header employed by 802.1d. This is to further differentiate these BPDUs from those used by IEEE 802.1d bridges, in the event that some of those bridges do not correctly identify multicast MAC addresses<sup>9</sup>.
+- IEEE 802.1d BPDUs are ignored and silently discarded.
+- Topology Change Notification (TCN) PDUs are not transmitted (or processed). TCNs are used in IEEE networks to accelerate the aging of the learning database when the network topology may have changed. Since the learning mechanism within the cable network typically differs, this message is unnecessary and may result in unnecessary flooding.
+- CMTSs operating as bridges must participate in this protocol and must be assigned higher priorities (more likely to be root) than cable modems. The NSI interface on the CMTS SHOULD be assigned a port cost equivalent to a link speed of at least 100 Mbit/s. These two conditions, taken together, should ensure that:
+  - 1) a CMTS is the root; and
+  - 2) any other CMTS will use the head-end network rather than a customer network to reach the root.
+- The MAC Forwarder of the CMTS MUST forward BPDUs from upstream to downstream channels, whether or not the CMTS is serving as a router or a bridge.
+
+<sup>9</sup> It is likely that there are a number of spanning tree bridges deployed which rely solely on the LSAPs to distinguish 802.1d packets. Such devices would not operate correctly if the data-over-cable BPDUs also used LSAP = 0x42.
+
+Note that CMs with this protocol enabled will transmit BPDUs onto subscriber networks in order to identify other CMs on the same subscriber network. These public spanning tree BPDUs will be carried transparently over any bridged private subscriber network. Similarly, bridging CMTSs will transmit BPDUs on the NSI as well as on the RFI interface. The multicast address and SNAP header defined above are used on all links.
+
+#### B.VIII.4 Spanning tree parameters and defaults
+
+Subclause 4.10.2 of [IEEE 802.1d] specifies a number of recommended parameter values. Those values should be used, with the exceptions listed below.
+
+##### Path Cost
+
+In [IEEE 802.1d], the following formula is used:
+
+$$\text{Path\_Cost} = 1000 / \text{Attached\_LAN\_speed\_in\_Mbit/s}$$
+
+For CMs, this formula is adapted as:
+
+$$\text{Path\_Cost} = 1000 / (\text{Upstream\_symbol\_rate} * \text{bits\_per\_symbol\_for\_long\_data\_grant})$$
+
+That is, the modulation type (QPSK or 16 QAM) for the Long Data Grant IUC is multiplied by the raw symbol rate to determine the nominal path cost. Table B.VIII-1 provides the derived values.
+
+For CMTSs, this formula is:
+
+$$\text{Path\_Cost} = 1000 / (\text{Downstream\_symbol\_rate} * \text{bits\_per\_symbol})$$
+
+**Table B.VIII-1/J.112 – CM path cost**
+
+| Symbol rate | Default path cost |        |
+|-------------|-------------------|--------|
+|             | QPSK              | 16 QAM |
+| ksym/s      |                   |        |
+| 160         | 3125              | 1563   |
+| 320         | 1563              | 781    |
+| 640         | 781               | 391    |
+| 1280        | 391               | 195    |
+| 2560        | 195               | 98     |
+
+##### Bridge Priority
+
+The Bridge Priority for CMs SHOULD default to 28672 (0x7000). This is to bias the network so that the root will tend to be at the CMTS. The CMTS SHOULD default to 32768, as per 802.1d.
+
+Note that both of these recommendations affect only the *default* settings. These parameters, as well as others defined in 802.1d, SHOULD be manageable throughout their entire range through the Bridge MIB (RFC-1493) or other means.
+
+## Annex C
+
+### Multimedia data transmission equipment over cable television network
+
+#### C.1 Introduction
+
+This annex is derived from work done on multimedia data transmission equipment designed to be used in cable television networks in Japan. An asymmetrical multimedia data system is described, for use on cable television systems of up to 770 MHz, to enable bi-directional IP datagram transmission.
+
+#### C.2 Definition of reference system and Interfaces
+
+Figure C.2-1 depicts the reference system and the interface points to define the overall multimedia data transmission system and equipment.
+
+The multimedia transmission system comprises Multimedia Center (MC) equipment, an administrative system, a security system, and Multimedia Home (MH) equipment. MC is usually installed at a cable television Head End or Center and is connected to external interface equipment. MH is mainly installed in residential homes or offices and is connected to customer premises equipment, i.e. personal computers. MC has two major functions; one is the distribution of multimedia data, including IP traffic, from an external network to hundreds of MH equipment connected to the CATV network. The other is the collection of upstream data from MHs. The role of the administrative system is to control daily operations, maintenance, tariff and billings, etc., required to support CATV network systems. MC may include these facilities in the case of a small network. A security system should be installed to intercept third party theft or tampering with data between MC and MH. In some cases, this system may also be included in MC equipment.
+
+Five interface points, A, B, C, D and E, are shown in Figure C.2-1. However, the description of interface points D and E are out of the scope of this annex.
+
+![Figure C.2-1/J.112 – Reference system and interface points. The diagram shows the flow of data from an External Network through a CATV Center (containing External Interface Equipment, MC, Security System, and Administrative System) to a Home (containing MH and Personal Computer) via an HFC or Coaxial CATV Network. Interface points A, B, C, D, and E are marked.](59417013c6759d15ff749c2026e6f726_img.jpg)
+
+The diagram illustrates the reference system and interface points for multimedia data transmission over a cable television network. On the left, an 'External Network' (represented by an oval) connects to a 'CATV Center'. Inside the 'CATV Center', there are four main components: 'External Interface Equipment', 'MC' (Multimedia Center), 'Security System', and 'Administrative System'. The 'External Interface Equipment' is connected to the 'External Network' and the 'MC'. The 'Security System' and 'Administrative System' are connected to the 'MC' via dashed lines. 'Interface D' is the connection point between the 'External Interface Equipment' and the 'MC'. 'Interface E' is the connection point between the 'Administrative System' and the 'MC'. The 'MC' is connected to an 'HFC or Coaxial CATV Network'. 'Interface A' is the connection point between the 'External Interface Equipment' and the 'MC'. 'Interface B' is the connection point between the 'MC' and the 'HFC or Coaxial CATV Network'. The 'HFC or Coaxial CATV Network' connects to a 'Home'. Inside the 'Home', there are two components: 'MH' (Multimedia Home) and 'Personal Computer'. The 'MH' is connected to the 'HFC or Coaxial CATV Network' and the 'Personal Computer'. 'Interface C' is the connection point between the 'MH' and the 'Personal Computer'. The diagram is labeled 'T0905260-97/d112a' in the bottom right corner.
+
+Figure C.2-1/J.112 – Reference system and interface points. The diagram shows the flow of data from an External Network through a CATV Center (containing External Interface Equipment, MC, Security System, and Administrative System) to a Home (containing MH and Personal Computer) via an HFC or Coaxial CATV Network. Interface points A, B, C, D, and E are marked.
+
+MC Multimedia Center Equipment  
+MH Multimedia Home Equipment
+
+Figure C.2-1/J.112 – Reference system and interface points
+
+### C.3 Protocol stacks
+
+#### C.3.1 Interface A protocol stack
+
+Figure C.3-1 depicts the protocol stack at Interface A, connecting MC and external interface equipment. This shows the required protocols for IP over IEEE 802 implementations as an example. Other possible implementations using IP over ATM, or IP over FDDI, should adopt open protocols that are in common use.
+
+|                 |                                |
+|-----------------|--------------------------------|
+| Network Layer   | ..... IP                       |
+| Data Link Layer | ..... 802.2 LLC<br>[ 802.3 MAC |
+| Physical Layer  | ..... 10 Base-T, 100 Base-T    |
+
+**Figure C.3-1/J.112 – Protocol stack for Interface A**
+
+#### C.3.2 Interface A physical layer and data link layer
+
+The physical layer and data link layer at Interface A should have at least one function to carry IP traffic as defined as follows. The IP data shall be transmitted transparently and bi-directionally through the layers.
+
+- ATM STS-3C
+- FDDI
+- IEEE 802.3 10 Base-T
+- IEEE 802.3 100 Base-T
+- Ethernet 10 Base-T
+- Ethernet 100 Base-T
+
+#### C.3.3 Interface A network layer
+
+The network layer of interface A should be Internet Protocol (IP), version 4. This Recommendation is expected to evolve to support IP version 6 (IETF RFC 1883) as it becomes an accepted standard. The IP data shall be transmitted transparently and bi-directionally through the layer.
+
+#### C.3.4 Interface B protocol stack
+
+Figure C.3-2 shows the protocol stack of interface B to be specified between MC and MH. The most important task of MC and MH is to transmit IP datagrams transparently between cable head end and customer premises. Both MC and MH should work as an IP host, which means supporting IP over LLC/DIX protocol as a part of the Data Link Layer. The physical layer should consist of a Transmission Convergence (TC) layer and a PMD (Physical Media Dependent) layer.
+
+|                 |
+|-----------------|
+| Data Link Layer |
+| Physical Layer  |
+
+**Figure C.3-2/J.112 – Protocol stack of Interface B**
+
+### C.3.5 Interface C protocol stack
+
+Figure C.3-3 depicts a protocol stack for Interface C, combining MH and PC.
+
+![Protocol stack diagram for Interface C showing three layers: Network Layer, Data Link Layer, and Physical Layer.](393d4a0608986a997ae261bdaa50e9b9_img.jpg)
+
+|                 |
+|-----------------|
+| Network Layer   |
+| Data Link Layer |
+| Physical Layer  |
+
+Protocol stack diagram for Interface C showing three layers: Network Layer, Data Link Layer, and Physical Layer.
+
+**Figure C.3-3/J.112 – Protocol stack at Interface C**
+
+### C.3.6 Interface C physical layer and data link layer
+
+As the IP traffic must be passed transparently to the PC, LLC and MAC protocols should be adopted in the data link layer. IEEE 802.3 10 Base-T or Ethernet 10 Base-T should be the physical layer protocol. The following protocols should be implemented in the data link layer and physical layer.
+
+- 802.2/DIX
+- 802.3/DIX
+- IEEE 802.3 10 Base-T
+- Ethernet 10 Base-T
+
+### C.3.7 Interface C network layer
+
+The network layer of interface C should be Internet Protocol (IP), version 4. This specification is expected to evolve to support IP version 6 (IETF RFC 1883) as it becomes an accepted standard. The IP data shall be transmitted transparently and bi-directionally through the layer.
+
+## C.4 Physical layer specification
+
+### C.4.1 Upstream
+
+#### C.4.1.1 Modulation method
+
+QPSK modulation method should be applied for upstream channel.
+
+#### C.4.1.2 Signal constellation diagram and phase shift rule
+
+In the following Table C.4-1,  $I_n$  is in-phase component, while  $Q_n$  denotes quadrant component.  $I_1$  means the MSB (Most Significant Bit) of the symbol map.
+
+**Table C.4-1/J.112 – Definition of data  $I_n$  and  $Q_n$**
+
+| Modulation method | Input bit definitions |
+|-------------------|-----------------------|
+| QPSK              | $I_1$ $Q_1$           |
+
+Equipment should have differential-coded QPSK. Figure C.4-1 shows the signal constellation diagram for QPSK modulation in general form, and Table C.4-2 provides the phase shift rule of differential-coded QPSK modulation.
+
+![QPSK Signal Constellation Diagram showing four quadrants with bit pairs: 00 (top-right), 01 (bottom-right), 11 (bottom-left), and 10 (top-left). The horizontal axis is labeled I1 and the vertical axis is labeled Q1. A small label T0905270-97/d112b is at the bottom right.](a3476b0e9a7807008e84337e16b34837_img.jpg)
+
+QPSK Signal Constellation Diagram showing four quadrants with bit pairs: 00 (top-right), 01 (bottom-right), 11 (bottom-left), and 10 (top-left). The horizontal axis is labeled I1 and the vertical axis is labeled Q1. A small label T0905270-97/d112b is at the bottom right.
+
+**Figure C.4-1/J.112 – QPSK Signal Constellation Diagram**
+
+**Table C.4-2/J.112 – Phase shift rule for differential-coded QPSK**
+
+| Input<br>$I_1 \ Q_1$ | Phase Shift Output |
+|----------------------|--------------------|
+| 0 0                  | 0 degree           |
+| 1 0                  | +90 degrees        |
+| 1 1                  | +180 degrees       |
+| 0 1                  | +270 degrees       |
+
+**C.4.1.3 Symbol Rate, Bandwidth and Roll Off**
+
+In some countries, the upstream channel has been used to transmit several 6 MHz video signals. In order to utilize the limited bandwidth efficiently, the bandwidth of the upstream channel is strongly recommended to be integer-divided value of 6 MHz or 6 MHz/n.
+
+The value "n" shall be carefully chosen to form a series of integer-related upstream bandwidths. Appropriate Roll Off value should be selected from the viewpoint of effective band separation and manufacturing. Furthermore, the preferable symbol rate should be multiples of 8kHz, for synchronization with external transmission lines if required. The resulting values of "n" should be 2, 4, 8, 16 and 32. The Roll Off factor should be 25%.
+
+Table C.4-3 summarizes Integer n, Bandwidth and Symbol Rate. The upstream channel must support all symbol rates shown.
+
+**Table C.4-3/J.112 – Integer n, Bandwidth and Symbol Rate**
+
+| Integer n | 6 MHz/n<br>Bandwidth<br>(kHz) | Symbol Rate<br>(ksym/s) |
+|-----------|-------------------------------|-------------------------|
+| 2         | 3000.0                        | 2304                    |
+| 4         | 1500.0                        | 1152                    |
+| 8         | 750.0                         | 576                     |
+| 16        | 375.0                         | 288                     |
+| 32        | 187.5                         | 144                     |
+
+**C.4.1.4 Frequency range**
+
+The upstream channel must support a 10 MHz to 55 MHz frequency range.
+
+#### C.4.1.5 Error correction
+
+Error correction functionality shall be considered for the noise environment in the cable television network. A Reed-Solomon Code should be implemented as an error correction function for the upstream modulator.
+
+The original Reed-Solomon code is defined as follows:
+
+- Field generator polynomial:  $p(X) = X^8 + X^4 + X^3 + X^2 + 1$ .
+- Code generator polynomial:  $g(X) = (X + \alpha^0)(X + \alpha^1)\cdots(X + \alpha^{2T-1})$ ,
+
+where T is error correcting capability of a Reed-Solomon code and  $\alpha$  is 02H and one of roots of equation  $p(X) = 0$ .
+
+#### C.4.1.6 Randomization
+
+The upstream modulator should provide a randomization function. The polynomial should be  $X^{15} + X^{14} + 1$ .
+
+#### C.4.1.7 Transmission signal level
+
+The transmitting signal level at MH output connector should be adjustable over the range +70 to +110 dB $\mu$ V. Level adjustment step should be 1dB.
+
+#### C.4.1.8 Receiving signal level
+
+The operational receiving signal level at MC input connector should satisfy the values in Table C.4-4.
+
+In the case that transmission level control is applied, signals can be received within a part of the range mentioned above.
+
+**Table C.4-4/J.112 – Symbol Rate and nominal receive level**
+
+| Symbol Rate (ksym/s) | Nominal receive level (dB $\mu$ V) |
+|----------------------|------------------------------------|
+| 144                  | +44 to +72                         |
+| 288                  | +47 to +75                         |
+| 576                  | +50 to +78                         |
+| 1152                 | +53 to +81                         |
+| 2304                 | +56 to +84                         |
+
+#### C.4.1.9 Transmission spurious
+
+The noise and spurious power should not exceed the values shown in Table C.4-5.
+
+The measurement bandwidth is equal to the symbol rate for the requirement below 55 MHz.
+
+The digital carrier level is expected to be –10 dB lower than the analogue NTSC carrier.
+
+**Table C.4-5/J.112 – Noise and spurious powers**
+
+| Frequency                                                                                                      | Active period            | Inactive period          |
+|----------------------------------------------------------------------------------------------------------------|--------------------------|--------------------------|
+| 10 to 55 MHz, Inband                                                                                           | Less than –40 dBc        | Less than +30 dB $\mu$ V |
+| 10 to 55 MHz, Outband including adjacent band, carrier-related band and other noise powers within 10 to 55 MHz | Less than –45 dBc        |                          |
+| 55 to 90 MHz                                                                                                   | Less than +35 dBmV       |                          |
+| 90 to 770 MHz                                                                                                  | Less than +35 dB $\mu$ V |                          |
+
+#### C.4.1.10 Bit error rate
+
+Bit error rate of the upstream signal should be less than  $10^{-6}$  at C/N = 20 dB (Nyquist bandwidth) without error correction.
+
+#### C.4.1.11 Frame structure
+
+The frame structure should have the following general format (see Figure C.4-2). Actual length in bits should be defined in the data link layer protocol specifications.
+
+![Diagram of frame structure showing a sequence of fields: Preamble, Payload, FEC, Payload, FEC, a dashed box representing variable length, Payload, FEC, and GT.](bcc5e48817a7383c980f2165bb571508_img.jpg)
+
+|          |         |     |         |     |       |         |     |    |
+|----------|---------|-----|---------|-----|-------|---------|-----|----|
+| Preamble | Payload | FEC | Payload | FEC | ----- | Payload | FEC | GT |
+|----------|---------|-----|---------|-----|-------|---------|-----|----|
+
+Diagram of frame structure showing a sequence of fields: Preamble, Payload, FEC, Payload, FEC, a dashed box representing variable length, Payload, FEC, and GT.
+
+T0905940-97/d113
+
+GT Guard Time  
+FEC Forward Error Correction
+
+Figure C.4-2/J.112 – Frame structure
+
+#### C.4.1.12 Channel frequency accuracy
+
+Channel frequency accuracy should be within  $\pm 50$  ppm over a temperature range of 0 to 40 degrees C.
+
+#### C.4.1.13 Symbol rate accuracy
+
+Symbol rate accuracy should be within  $\pm 50$  ppm over a temperature range of 0 to 40 degrees C.
+
+### C.4.2 Downstream
+
+#### C.4.2.1 Modulation method
+
+The modulation method should be 64 QAM.
+
+#### C.4.2.2 Signal constellation diagram and phase shift rule
+
+The signal constellation diagram and phase shift rule should be compliant with Annex C/J.83.
+
+#### C.4.2.3 Symbol rate and bandwidth
+
+The symbol rate should be 5.274 Msym/s. Bandwidth should be 6 MHz. Other parameters related to symbol rate and bandwidth should be compliant with Annex C/J.83.
+
+#### C.4.2.4 Frequency range
+
+The downstream channel must support a 90 MHz to 770 MHz frequency range.
+
+#### C.4.2.5 Error correction
+
+Error correction functionality shall be considered for the noise environment in the cable television network. Code length and information byte length should be in accordance with Annex C/J.83.
+
+The original Reed-Solomon code is defined as follows:
+
+- Field generator polynomial:  $p(X) = X^8 + X^4 + X^3 + X^2 + 1$ .
+- Code generator polynomial:  $g(X) = (X + \alpha^0)(X + \alpha^1)\cdots(X + \alpha^{2T-1})$ ,
+
+where T is error correcting capability of a Reed-Solomon code and  $\alpha$  is 02H and one of roots of equation  $p(X) = 0$ .
+
+#### C.4.2.6 Randomization
+
+A randomization function should be provided. The generator polynomial should be compliant with Annex C/J.83.
+
+#### C.4.2.7 Interleave
+
+The interleave method should be compliant with Annex C/J.83.
+
+#### C.4.2.8 Transmission signal level
+
+The transmission signal level at MC output connector should be adjustable over the range of +100 to +110 dB $\mu$ V.
+
+#### C.4.2.9 Receiving signal level
+
+MH should be able to operate at the level within a range of +53 dB $\mu$ V to +85 dB $\mu$ V at MH input connector.
+
+#### C.4.2.10 Transmission spurious
+
+Transmission spurious level should be less than -55 dBc over the range of 90 MHz to 770 MHz. The digital carrier level is expected to be 10 dB lower than the analogue NTSC carrier.
+
+#### C.4.2.11 Bit error rate
+
+Bit error rate should be less than  $10^{-8}$  at CNR = 27 dB (Nyquist bandwidth) with error correction.
+
+#### C.4.2.12 Channel frequency accuracy
+
+Channel frequency accuracy should be within  $\pm 20$  ppm over a temperature range of 0 to 40° C.
+
+#### C.4.2.13 Symbol rate accuracy
+
+Symbol rate accuracy should be within  $\pm 20$  ppm over a temperature range of 0 to 40° C.
+
+#### C.4.2.14 Impedance, Return Loss and Connector
+
+Impedance, Return Loss and Connector at MH In/Output, MC Output and MC Input should meet the requirements shown in Table C.4-6.
+
+**Table C.4-6/J.112 – Impedance, Return Loss and Connector**
+
+|              | Impedance   | Return Loss                     | Connector       |
+|--------------|-------------|---------------------------------|-----------------|
+| MH In/Output | 75 $\Omega$ | 6 dB<br>10-55 and<br>90-770 MHz | F-type, Female  |
+| MC Output    | 75 $\Omega$ | 14 dB<br>90-770 MHz             | F-type, Female  |
+| MC Input     | 75 $\Omega$ | 6 dB<br>10-55 MHz               | F- type, Female |
+
+### C.5 Transmission convergence sublayer specification
+
+#### C.5.1 Introduction
+
+A Transmission Convergence (TC) sublayer is provided for MPEG video and data services. In order to facilitate multiplexing and demultiplexing at TC sublayer, the physical layer is divided into transmission convergence layer and physical media dependent layer. The frame for TC layer is based on Recommendation H.222.0 (188 bytes MPEG packet). An MPEG packet consists of a 4-byte header and 184-byte payload. The payload type can be discriminated by the header. As shown in Figure C.5-1, Video and DOC (Data over Cable) headers are defined to identify the payload type.
+
+|                |                       |
+|----------------|-----------------------|
+| header = DOC   | DOC MAC payload       |
+| header = video | digital video payload |
+| header = video | digital video payload |
+| header = DOC   | DOC MAC payload       |
+| header = video | digital video payload |
+| header = DOC   | DOC MAC payload       |
+| header = video | digital video payload |
+| header = video | digital video payload |
+| header = video | digital video payload |
+
+**Figure C.5-1/J.112 – Downstream TC layer framing**
+
+### C.5.2 MPEG Packet format
+
+Figure C.5-2 depicts the format of an MPEG Packet. The pointer field shall be inserted if necessary.
+
+|                          |                           |                               |
+|--------------------------|---------------------------|-------------------------------|
+| MPEG Header<br>(4 bytes) | Pointer_field<br>(1 byte) | Payload<br>(183 or 184 bytes) |
+|--------------------------|---------------------------|-------------------------------|
+
+**Figure C.5-2/J.112 –MPEG Packet format**
+
+### C.5.3 MPEG Header
+
+The header of the MPEG transport stream is based on the definition of Recommendation H.222.0 as shown in Table C.5-1.
+
+**Table C.5-1/J.112 – MPEG Packet format**
+
+| Field                                                           | Length (bits) | Description                                                                                                                                                                     |
+|-----------------------------------------------------------------|---------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| sync_byte                                                       | 8             | 0x47; MPEG Packet Sync byte                                                                                                                                                     |
+| transport_error_indicator                                       | 1             | Indicates an error has occurred in the reception of the packet. This bit is reset to zero by the sender, and set to one whenever an error occurs in transmission of the packet. |
+| payload_unit_start_indicator                                    | 1             | A value of one indicates the presence of a pointer_field as the first byte of the payload (fifth byte of the packet)                                                            |
+| transport_priority                                              | 1             | Reserved, set to zero.                                                                                                                                                          |
+| PID (Note)                                                      | 13            | Data over Cable PID (0x1FFE)                                                                                                                                                    |
+| transport_scrambling_control                                    | 2             | Reserved, set to '00'.                                                                                                                                                          |
+| adaptation_field_control                                        | 2             | '01'; use of the adaptation_field is NOT ALLOWED on the PID.                                                                                                                    |
+| continuity_counter                                              | 4             | Cyclic counter within this PID                                                                                                                                                  |
+| NOTE – In the future, additional PIDs MAY be assigned to an MH. |               |                                                                                                                                                                                 |
+
+### C.5.4 Interface with MAC sublayer
+
+There shall be several cases for the relationship of MAC frames to MPEG packets. An MPEG Packet can contain multiple MAC frames, or contain one MAC Frame that applies over multiple MPEG packets.
+
+Figure C.5-3 shows a MAC Frame starting immediately after a pointer field. In this case the pointer field is set to "0" and the decoder shall recognize the head of the MAC Frame after searching the next bytes, except for 0xFF pattern.
+
+|                           |                        |                                |                              |
+|---------------------------|------------------------|--------------------------------|------------------------------|
+| MPEG Header<br>(PUSI = 1) | pointer_field<br>(= 0) | MAC Frame<br>(up to 183 bytes) | stuff_byte(s)<br>(0 or more) |
+|---------------------------|------------------------|--------------------------------|------------------------------|
+
+**Figure C.5-3/J.112 – MAC Frame mapping (1)**
+
+Figure C.5-4 shows the case where a MAC Frame continues from the tail of the previous MAC Frame. The pointer shows the next byte of MAC Frame #1. The decoder shall search byte by byte until it finds the pattern, except for 0xFF, from the next byte of the last MAC Frame #1.
+
+|                           |                        |                                   |                              |                       |
+|---------------------------|------------------------|-----------------------------------|------------------------------|-----------------------|
+| MPEG Header<br>(PUSI = 1) | pointer_field<br>(= M) | Tail of MAC Frame #1<br>(M bytes) | stuff_byte(s)<br>(0 or more) | Start of MAC Frame #2 |
+|---------------------------|------------------------|-----------------------------------|------------------------------|-----------------------|
+
+**Figure C.5-4/J.112 – MAC Frame mapping (2)**
+
+Figure C.5-5 shows that multiple MAC frames exist in an MPEG Packet. The pointer should detect the head of MAC Frame #1. The head of the second MAC Frame shall be found after searching patterns except for 0xFF from the position of the head of MAC Frame #1 and succeeding frame length. Thus the MAC Frame should be detected by the end of the MPEG Packet.
+
+|                           |                        |              |              |                              |              |
+|---------------------------|------------------------|--------------|--------------|------------------------------|--------------|
+| MPEG Header<br>(PUSI = 1) | pointer_field<br>(= 0) | MAC Frame #1 | MAC Frame #2 | stuff_byte(s)<br>(0 or more) | MAC Frame #3 |
+|---------------------------|------------------------|--------------|--------------|------------------------------|--------------|
+
+**Figure C.5-5/J.112 – MAC Frame mapping (3)**
+
+Figure C.5-6 shows the case of a MAC Frame overrunning multiple MPEG packets. In this case the pointer field of the succeeding frame points to the byte following the last byte of the tail of the first frame.
+
+|                           |                                             |                                   |                                            |                                    |
+|---------------------------|---------------------------------------------|-----------------------------------|--------------------------------------------|------------------------------------|
+| MPEG Header<br>(PUSI = 1) | pointer_field<br>(= 0)                      | stuff_byte(s)<br>(0 or more)      | Start of MAC Frame #1<br>(up to 183 bytes) |                                    |
+| MPEG Header<br>(PUSI = 0) | Continuation of MAC Frame #1<br>(184 bytes) |                                   |                                            |                                    |
+| MPEG Header<br>(PUSI = 1) | pointer_field<br>(= M)                      | Tail of MAC Frame #1<br>(M bytes) | stuff_byte(s)<br>(0 or more)               | Start of MAC Frame #2<br>(M bytes) |
+
+**Figure C.5-6/J.112 – MAC Frame mapping (4)**
+
+### C.5.5 Physical layer interaction
+
+The MPEG-2 packet stream should be encoded in accordance with Annex C/J.83.
+
+### C.5.6 MPEG Header synchronization and recovery
+
+The MPEG-2 Packet stream should be in "in frame" state after receiving consecutive five packets without parity check errors. The MPEG-2 Packet should be in "out of frame" state after receiving nine consecutive packets with parity check errors.
+
+## C.6 MAC layer specification
+
+### C.6.1 Introduction
+
+#### C.6.1.1 Overview
+
+Figure C.6-1 shows an aspect of the multimedia data transmission system and MAC sublayer domain. The MAC sublayer domain consists of a Multimedia Center (MC) equipment and multiple upstreams and downstreams that connect MC and multimedia Home (MH) equipment. The transmission speed of the downstream is about 30 Mbit/s while the upstream is from about 100 kbit/s to a few Mbit/s. An MH can access an upstream and downstream pair.
+
+Bandwidth assignment for downstream is controlled by the combination of FDM and TDM. Each MH has an assigned receiving channel among multiple downstream channels, and multiple data for MH are multiplexed on a time division basis over the downstream. Bandwidth assignment for upstream is controlled by the combination of FDMA and TDMA. MH has an assigned transmission channel among upstream channels and transmits data after time assignment of upstream channel by multi-access control.
+
+![Diagram of network construction showing a Multimedia Center (MC) connected to the Internet and four Multimedia Homes (MH) via Downstream and Upstream channels. Each MH is connected to a PC.](4aeafa83d297a9b124c73904c5a49437_img.jpg)
+
+The diagram illustrates a network construction. On the left, an oval labeled 'Internet' is connected to a rectangular box labeled 'MC' (Multimedia Center). From the 'MC', four horizontal lines extend to the right, labeled 'Downstream channels' at the top. Below these, four more horizontal lines extend to the right, labeled 'Upstream channels' at the bottom. Each of these four lines has an arrow pointing to the right. Below the 'MC', there are four rectangular boxes labeled 'MH' (Multimedia Home), arranged horizontally. Each 'MH' is connected to the 'MC' by a vertical double-headed arrow. Below each 'MH' is another rectangular box labeled 'PC' (Personal Computer), connected by a vertical line. At the bottom right of the diagram, the text 'T0905280-97/d1114' is present.
+
+Diagram of network construction showing a Multimedia Center (MC) connected to the Internet and four Multimedia Homes (MH) via Downstream and Upstream channels. Each MH is connected to a PC.
+
+Figure C.6-1/J.112 – Network construction
+
+#### C.6.1.2 Bandwidth assignment
+
+Figure C.6-2 depicts bandwidth assignment by mini-slots and messages. The upstream channel is divided into small slots called mini-slots. The size of a mini-slot is in multiples of a timebase tick that is selected to be a multiple of the reciprocal of highest symbol rate in upstream. The MC can assign several mini-slots to MH as needed and MH transmits data by combining these mini-slots. Mini-slot assignment is controlled by messages and MC shall transmit the bandwidth assignment message called MAP. MAP contains information for bandwidth assignment as Information Elements (IE). Each IE contains mini-slot start index, mini-slot number to be assigned, service ID and usage of the bandwidth. In Figure C.6-2, mini-slot #N is for random reservation which all MH can access, mini-slots #N + 1 to N + 3 are for random access, mini-slots #N + 4 to N + 7 are for the data domain of specific MH (#a). After receiving MAP, MH should start analysis of IE in the MAP, then transmit data at available mini-slots.
+
+![Diagram of bandwidth assignment by mini-slot and message. It shows a timeline with Downstream and Upstream directions. Mini-slots are numbered N, N+1, N+2, N+3, N+4, N+5. Arrows indicate message exchanges: 1) Transmission Bandwidth Allocation Message, 2) Reservation data in request, 3) Contention resolution by Exponential Binary Back-off, 4) Bandwidth assign to MH, 5) Transmit next reservation data with piggyback. A legend indicates N, N+1~3, and N+4~7 are reserved for Station #a.](c79d10d97e1f525e9c85e96e91616923_img.jpg)
+
+1) Transmission Bandwidth Allocation Message
+
+N:  
+N + 1~3  
+N + 4~7 Reserved for Station #a
+
+3) Contention resolution by Exponential Binary Back-off
+
+Downstream
+
+---
+
+Upstream
+
+---
+
+MINI-SLOT
+
+N N + 1 N + 2 N + 3 N + 4 N + 5 N + 4 N + 5
+
+2) Reservation data in request
+
+2') Reservation data in request/data domain
+
+4) Bandwidth assign to MH
+
+5) Transmit next reservation data with piggyback
+
+T0905290-97/d1115
+
+Diagram of bandwidth assignment by mini-slot and message. It shows a timeline with Downstream and Upstream directions. Mini-slots are numbered N, N+1, N+2, N+3, N+4, N+5. Arrows indicate message exchanges: 1) Transmission Bandwidth Allocation Message, 2) Reservation data in request, 3) Contention resolution by Exponential Binary Back-off, 4) Bandwidth assign to MH, 5) Transmit next reservation data with piggyback. A legend indicates N, N+1~3, and N+4~7 are reserved for Station #a.
+
+**Figure C.6-2/J.112 – Bandwidth assignment by mini-slot and message**
+
+### C.6.1.3 Mini-slot synchronization
+
+Figure C.6-3 shows mini-slot synchronization that enables the synchronization of mini-slot numbers and boundaries for all MHs connected.
+
+- 0) MC measures Round Trip Delay (RTD) between MC and each MH and notifies it to MH in advance.
+  - 1) MC keeps a Global Time (GT) counter operated by a timebase tick and informs periodically this counter value to all MHs as timestamp information.
+- MC controls mini-slot number and boundary based on GT.
+- 2) Each MH adjusts Local Time (LT) by timestamp received.
+  - 3) MH recognizes the mini-slot boundary and number by LT. The mini-slot number N is defined as  $N = LT/M$ , where M is defined as  $LT \bmod M = 0$ .
+  - 4) MH transmits data to assigned mini-slot #N.
+  - 5) The data arrives at MC at GT that equals  $N \times M$ .
+
+![Diagram of global timing synchronization. It shows a timeline with Downstream and Upstream directions. Mini-slots are numbered N-2, N-1, N, N+1, N+2, N+3. Arrows indicate message exchanges: 0) Measurement of RTD in advance, 1) Periodic transmission of Timing Reference, 2) Local time adjust after timing reference, 3) Mini-slot Index, 4) Transmit data to Mini-slot #N, 5) Data arrival at GT = N x M. Formulas for LT and GT are provided.](5ed662a589ef8a6d08d67ae2fd275216_img.jpg)
+
+1) Periodic transmission of Timing Reference  
+Global Time (GT) = T0
+
+0) Measurement of RTD in advance
+
+Downstream
+
+---
+
+Upstream
+
+---
+
+RTDd RTDu
+
+Mini-slot Size = M
+
+N - 2 N - 1 N N + 1 N + 2 N + 3
+
+2) Local time adjust after timing reference  
+ $LT = T0 + RTD$   
+ $(GT = T0 + RTDd)$
+
+3) Mini-slot Index =  $LT/M$
+
+4) Transmit data to Mini-slot #N  
+ $LT = N \times M$   
+ $(GT = N \times M - RTDu)$
+
+5) Data arrival at  
+ $GT = N \times M$
+
+T0905300-97/d1116
+
+Diagram of global timing synchronization. It shows a timeline with Downstream and Upstream directions. Mini-slots are numbered N-2, N-1, N, N+1, N+2, N+3. Arrows indicate message exchanges: 0) Measurement of RTD in advance, 1) Periodic transmission of Timing Reference, 2) Local time adjust after timing reference, 3) Mini-slot Index, 4) Transmit data to Mini-slot #N, 5) Data arrival at GT = N x M. Formulas for LT and GT are provided.
+
+**Figure C.6-3/J.112 – Global timing synchronization**
+
+### C.6.1.4 Access sequence
+
+The access sequence is primarily based on random reservation, however random access shall be available according to traffic volume. Descriptions are given in the following.
+
+#### C.6.1.4.1 Random reservation
+
+Figure C.6-4 shows the random reservation sequence. MC assigns a domain for the upstream channel to transmit reservation information periodically. MC notifies MH with mini-slot domain information set in MAP. The MH with data to be transmitted can transmit reservation information in the domain. If a collision occurs, MH can resend reservation information by binary exponential back-off algorithm. After resolution of collision, MC notifies MH the band assignment with mini-slot information. After receiving the information, MH should transmit data in the assigned domain.
+
+![Figure C.6-4/J.112 – Random reservation sequence diagram showing MC and MH(a)/MH(b) communication over time with MAP (Req IE) and MAP (Grant IE) messages, and MH transmissions of Req and Data.](28f9598c1cd4a12dcf83455c95ea4fcd_img.jpg)
+
+The diagram illustrates the random reservation sequence. At the top, five MAP messages are shown: three 'MAP (Req IE)' and two 'MAP (Grant IE)'. Below them, a horizontal timeline represents the channel. The 'MC' (Management Station) is shown on the left, with arrows pointing from the MAP messages to the timeline. The 'MH(a) MH(b)' (Mobile Stations) are shown below the timeline. Arrows from the timeline to the MHs indicate reception of MAP messages. Below the MHs, another horizontal timeline shows their transmissions: 'Req' (Reservation) messages are sent at various points, and 'Data + Req' and 'Data' messages are sent after receiving 'Grant IE' messages. A small text 'T0906700-98/d117' is visible in the bottom right corner of the diagram area.
+
+Figure C.6-4/J.112 – Random reservation sequence diagram showing MC and MH(a)/MH(b) communication over time with MAP (Req IE) and MAP (Grant IE) messages, and MH transmissions of Req and Data.
+
+Figure C.6-4/J.112 – Random reservation sequence
+
+#### C.6.1.4.2 Random access
+
+Generally random reservation realizes a high throughput because of less loss of capacity due to collisions. However it needs a reservation procedure before transmission, and thus increases latency. Random access does not need such a reservation procedure and reduces latency.
+
+Figure C.6-5 depicts the random access sequence. MC should set, regularly, mini-slot domain information that allows random access in MAP. MH should send data within the range of request/data IE indicated. In the case of a collision that means simultaneous data transmission by multiple MHs, retransmission can be done by the binary exponential back-off like random reservation. After receiving data acknowledgement, MH should quit retransmission. MC can stop random access if network traffic becomes heavy.
+
+![Figure C.6-5/J.112 – Random access sequence diagram showing MC and MH(a)/MH(b) communication over time with MAP (Req/Data IE) and MAP (Data Ack IE) messages, and MH transmissions of Data.](15ca9e79e42494966b608c4f0c6b64cc_img.jpg)
+
+The diagram illustrates the random access sequence. At the top, four MAP messages are shown: three 'MAP (Req/Data IE)' and one 'MAP (Data Ack IE)'. Below them, a horizontal timeline represents the channel. The 'MC' (Management Station) is shown on the left, with arrows pointing from the MAP messages to the timeline. The 'MH(a) MH(b)' (Mobile Stations) are shown below the timeline. Arrows from the timeline to the MHs indicate reception of MAP messages. Below the MHs, another horizontal timeline shows their transmissions: 'Data' messages are sent directly after receiving 'Req/Data IE' messages. A 'Data Ack IE' message is shown being sent from the MC to the MHs. A small text 'T0906710-98/d118' is visible in the bottom right corner of the diagram area.
+
+Figure C.6-5/J.112 – Random access sequence diagram showing MC and MH(a)/MH(b) communication over time with MAP (Req/Data IE) and MAP (Data Ack IE) messages, and MH transmissions of Data.
+
+Figure C.6-5/J.112 – Random access sequence
+
+### C.6.1.5 QOS by Service ID
+
+In order to assign the upstream bandwidth, a descriptor called Service ID (SID) is used. The purpose of SID is classifying MH and service type. MH should send SID in the reservation information in reservation status to make known to MC the required service grade and bandwidth assignment. MC can also authorize the service grade and MH to be assigned by an indication of SID.
+
+A minimum bandwidth information is defined at this moment as QOS information. MH can request several services besides best effort type service of minimum bandwidth. Upon receipt of the request, MC should assign SID for each service grade.
+
+## C.6.2 MAC Frame format
+
+### C.6.2.1 Generic MAC Frame format
+
+Figure C.6-6 shows a generic MAC Frame consisting physical layer overheads, MAC Header and Data PDU. PMD overhead includes preamble and synchronization pattern for upstream and MPEG PSI header for downstream.
+
+![Diagram of a generic MAC Frame structure showing PMD Overhead (upstream), MAC Header, Data PDU (optional), and MPEG PSI Header (downstream).](1eab323450a82831cf78035658284a51_img.jpg)
+
+The diagram illustrates the structure of a generic MAC Frame. It consists of several components:
+ 
+
+- PMD Overhead (upstream)**: A box at the top left representing physical layer overhead for upstream data.
+- MPEG PSI Header (downstream)**: A box at the bottom left representing the MPEG Program Specific Information header for downstream data.
+- MAC Frame**: A large bracket grouping the **MAC Header (Figure C.6-7)** and the **Data PDU (optional) (Figure C.6-8)**. These two components are shown as adjacent boxes in the center.
+- Reference**: The text T0905330-97/d1119 is located at the bottom right of the diagram.
+
+Diagram of a generic MAC Frame structure showing PMD Overhead (upstream), MAC Header, Data PDU (optional), and MPEG PSI Header (downstream).
+
+Figure C.6-6/J.112 – MAC Frame
+
+### C.6.2.2 MAC Header format
+
+An MAC Header format is shown in Figure C.6-7 and Table C.6-1. MAC Header specifies MAC Frame type and length as well as optional Extended Header (EHDR). EHDR can contain reservation information and extended information for virtual LAN descriptor.
+
+![Diagram of the MAC Header format showing fields FC, MAC_PARM, LEN (SID), EHDR, and HCS, with a detailed view of the FC field.](07a8dab6afb9f88d7e6ee8a283b53094_img.jpg)
+
+The diagram shows the MAC Header format and a detailed view of the FC field:
+ 
+
+- The main header structure is a horizontal row of five boxes: **FC (1 byte)**, **MAC\_PARM (1 byte)**, **LEN (SID) (2 bytes)**, **EHDR (0-255 bytes)** (indicated by a dashed border), and **HCS (bytes)**.
+- A dashed line with arrows points from the **FC (1 byte)** box to a detailed breakdown below it.
+- The detailed breakdown consists of three boxes: **FC\_TYPE (2 bits)**, **FC\_PARM (5 bits)**, and **EHDR\_ON (1 bit)**.
+- Reference**: The text T0905340-97/d120 is located at the bottom right of the diagram.
+
+Diagram of the MAC Header format showing fields FC, MAC\_PARM, LEN (SID), EHDR, and HCS, with a detailed view of the FC field.
+
+Figure C.6-7/J.112 – MAC Header format
+
+**Table C.6-1/J.112 – MAC Header format**
+
+| MAC Header Field | Usage                                                                                                                                                                                                                                                                     | Size           |
+|------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------|
+| FC               | Frame Control: Identifies type of MAC Header                                                                                                                                                                                                                              | 8 bits         |
+| MAC_PARM         | Parameter field whose use is dependent on FC:<br>if EHDR_ON = 1; used for EHDR field length (ELEN)<br>else if for concatenated frames (Table C.6-8) used for<br>MAC frame count<br>else (for Requests only) indicates the number of mini-slots and/or ATM cells requested | 8 bits         |
+| LEN (SID)        | The length of the MAC frame. The length is defined to be the sum of the number of bytes in the extended header (if present) and the number of bytes following the HCS field. (For a REQ Header, this field is the Service ID instead).                                    | 16 bits        |
+| EHDR             | Extended MAC Header (where present; variable size)                                                                                                                                                                                                                        | 0-255 bytes    |
+| HCS              | MAC Header check sequence                                                                                                                                                                                                                                                 | 2 bytes        |
+|                  | Length of a MAC Header                                                                                                                                                                                                                                                    | 6 bytes + EHDR |
+
+Table C.6-2 shows Frame Control (FC) field.
+
+**Table C.6-2/J.112 – FC field**
+
+| FC Field | Usage                                                                                                                                          | Size   |
+|----------|------------------------------------------------------------------------------------------------------------------------------------------------|--------|
+| FC_TYPE  | MAC Frame Control Type field:<br>00: Packet PDU MAC Header<br>01: ATM PDU MAC Header<br>10: Reserved PDU MAC Header<br>11: MAC Specific Header | 2 bits |
+| FC_PARM  | Parameter bits, use dependent on FC_TYPE.                                                                                                      | 5 bits |
+| EHDR_ON  | When = 1, indicates that EHDR field is present.<br>[Length of EHDR (ELEN) determined by MAC_PARM field]                                        | 1 bit  |
+
+**C.6.2.3 Data PDU**
+
+A data PDU succeeds a MAC header. As the Data PDU is an option, only the MAC header is transmitted in some cases. Data PDU type and format should be defined by FC field of MAC Header.
+
+**C.6.2.4 Packet-based MAC frames**
+
+MAC sublayer should support transmission of Ethernet/ISO/IEC 8802-3 type Packet Data PDU. Packet PDU contains DA to CRC but preamble and Start Frame Delimiter (SFD) in the Ethernet frame are as shown in Figure C.6-8.
+
+![Diagram of a Packet-based MAC frame structure. The top row shows the main fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Packet PDU (18-1518 bytes). Below FC, a dashed line points to a breakdown of its 8 bits: FC_TYPE (00), FC_PARM (00000), and EHDR_ON (0). Below the Packet PDU, a dashed line points to its internal structure: DA (6 bytes), SA (6 bytes), Type/Len (2 bytes), User Data (0-1500), and CRC (4 bytes).](11878e99fcab03106ffd86c24fbd11c9_img.jpg)
+
+Diagram of a Packet-based MAC frame structure. The top row shows the main fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Packet PDU (18-1518 bytes). Below FC, a dashed line points to a breakdown of its 8 bits: FC\_TYPE (00), FC\_PARM (00000), and EHDR\_ON (0). Below the Packet PDU, a dashed line points to its internal structure: DA (6 bytes), SA (6 bytes), Type/Len (2 bytes), User Data (0-1500), and CRC (4 bytes).
+
+T0905350-97/d121
+
+**Figure C.6-8/J.112 – Packet-based MAC frame**
+
+**Table C.6-3/J.112 – Packet-based MAC Frame format**
+
+| Field       | Usage                                                                                                                                                                                                                                                                                                                         | Size        |
+|-------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------|
+| FC          | FC_TYPE = 00; Packet MAC Header.<br>FC_PARM[4] = Data Link Encryption (DLE). If 1, then a security header for data link encryption is present (B.6.6). If zero, then no security header is present.<br>FC_PARM[3:0] = 000; other values reserved for future use and ignored.<br>EHDR_ON = 0; no EHDR present in this example. | 8 bits      |
+| MAC_PARM    | Reserved, MUST be set to zero if there is no EHDR; otherwise set to length of EHDR.                                                                                                                                                                                                                                           | 8 bits      |
+| LEN         | LEN = n; length of Packet PDU in bytes.                                                                                                                                                                                                                                                                                       | 16 bits     |
+| EHDR        | Extended MAC Header not present in this example                                                                                                                                                                                                                                                                               | 0 bytes     |
+| HCS         | MAC Header check sequence                                                                                                                                                                                                                                                                                                     | 2 bytes     |
+| Packet Data | Packet PDU:<br>DA – 48-bit Destination Address<br>SA – 48-bit Source Address<br>Type/Len – 16-bit Ethernet Type or [ISO/IEC 8802-3] Length Field<br>User Data (variable length, 0-1500 bytes)<br>CRC – 32-bit CRC over packet PDU (as defined in Ethernet/[ISO/IEC 8802-3])                                                   | n bytes     |
+|             | Length of Packet MAC Frame                                                                                                                                                                                                                                                                                                    | 6 + n bytes |
+
+**C.6.2.5 MAC-specific headers**
+
+MAC-specific header should control downstream timing, upstream ranging/power adjustment, bandwidth reservation and connection of multiple MAC frames.
+
+**C.6.2.5.1 Timing header**
+
+A timing header should be used for both upstream and downstream. MAC control messages should be set in a packet PDU. In the case of downstream, a timing header should be used for MC to send Global Timing Reference to synchronize with all MHs. A timing header should be also used for MH to send Ranging message to adjust timing and signal level in upstream channel (see Figure C.6-9 and Table C.6-4).
+
+![Diagram of MAC timing header structure. The top part shows a sequence of fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Packet PDU (various lengths). Below the FC field, a dashed line points to a detailed view of its 8-bit structure: FC_TYPE = 11, FC_PARM = 00000, and EHDR_ON = 0.](96f7fca1af2fc56edf670abd3ec79726_img.jpg)
+
+The diagram illustrates the structure of a MAC frame and the internal structure of the FC (Frame Control) field. The top row shows the main fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Packet PDU (various lengths). Below the FC field, a dashed line points to a detailed view of its 8-bit structure: FC\_TYPE = 11, FC\_PARM = 00000, and EHDR\_ON = 0.
+
+Diagram of MAC timing header structure. The top part shows a sequence of fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Packet PDU (various lengths). Below the FC field, a dashed line points to a detailed view of its 8-bit structure: FC\_TYPE = 11, FC\_PARM = 00000, and EHDR\_ON = 0.
+
+T0905360-97/d122
+
+**Figure C.6-9/J.112 – MAC timing header**
+
+**Table C.6-4/J.112 – MAC timing header format**
+
+| Field       | Usage                                                                                                                                           | Size        |
+|-------------|-------------------------------------------------------------------------------------------------------------------------------------------------|-------------|
+| FC          | FC_TYPE = 11; MAC-specific Header.<br>FC_PARM[4:0] = 00000; Timing MAC Header.<br>EHDR_ON = 0; extended header prohibited for SYNC and RNG-REQ. | 8 bits      |
+| MAC_PARM    | Reserved for future use                                                                                                                         | 8 bits      |
+| LEN         | LEN = n; length of Packet PDU in bytes.                                                                                                         | 16 bits     |
+| EHDR        | Extended MAC Header not present in this example                                                                                                 | 0 bytes     |
+| HCS         | MAC Header check sequence                                                                                                                       | 2 bytes     |
+| Packet Data | MAC Management message:<br>SYNC message (downstream only)<br>RNG-REQ (upstream only)                                                            | n bytes     |
+|             | Length of Packet MAC Frame                                                                                                                      | 6 + n bytes |
+
+**C.6.2.5.2 Management header**
+
+A management header indicates the head of a MAC Management message. A MAC Management message should be set in packet PDU domain (see Figure C.6-10 and Table C.6-5).
+
+![Diagram of MAC management header structure. The top row shows fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and MAC Management message. A dashed line from the FC field points to a detailed view below, which shows FC_TYPE = 11, FC_PARM = 00001, and EHDR_ON. The text T0905370-97/d123 is also present.](643af12d37ff807bcfea684e7c7abf31_img.jpg)
+
+Diagram of MAC management header structure. The top row shows fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and MAC Management message. A dashed line from the FC field points to a detailed view below, which shows FC\_TYPE = 11, FC\_PARM = 00001, and EHDR\_ON. The text T0905370-97/d123 is also present.
+
+**Figure C.6-10/J.112 – MAC management header**
+
+**Table C.6-5/J.112 – MAC management header format**
+
+| Field       | Usage                                                                 | Size                  |
+|-------------|-----------------------------------------------------------------------|-----------------------|
+| FC          | FC_TYPE = 11; MAC-specific Header.<br>FC_PARM[4:0] = 00001<br>EHDR_ON | 8 bits                |
+| MAC_PARM    | Reserved for future use                                               | 8 bits                |
+| LEN         | LEN = n; length of Packet PDU in bytes.                               | 16 bits               |
+| EHDR        | Extended MAC Header not present in this example                       | 0 bytes               |
+| HCS         | MAC Header check sequence                                             | 2 bytes               |
+| Packet Data | MAC Management message                                                | n bytes               |
+|             | Length of Packet MAC Frame                                            | 6 + n bytes<br>+ EHDR |
+
+### C.6.2.5.3 Request header
+
+MH should use MAC Header to reserve bandwidth in the upstream only. The header contains SID and necessary slot numbers/cell numbers information for MH to discriminate data priority. Figure C.6-11 and Table C.6-6 show request header and its format.
+
+![Diagram of MAC request header structure. The main header consists of four fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), and HCS (2 bytes). The FC field is expanded to show its internal bit structure: FC_TYPE = 11, FC_PARM = 00010, and EHDR_ON = 0.](db6a88d019f61d8c95703a54e12a0ec5_img.jpg)
+
+The diagram shows the structure of the MAC request header. The main header is a 6-byte structure: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), and HCS (2 bytes). The FC field is expanded to show its internal bit structure: FC\_TYPE = 11, FC\_PARM = 00010, and EHDR\_ON = 0.
+
+Diagram of MAC request header structure. The main header consists of four fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), and HCS (2 bytes). The FC field is expanded to show its internal bit structure: FC\_TYPE = 11, FC\_PARM = 00010, and EHDR\_ON = 0.
+
+Figure C.6-11/J.112 – MAC request header
+
+Table C.6-6/J.112 – MAC request header format
+
+| Field    | Usage                                                                                                                                                                                                                                                  | Size    |
+|----------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------|
+| FC       | FC_TYPE = 11; MAC-specific Header.<br>FC_PARM[3:0] = 0010; MAC Header only; no data PDU following.<br>FC_PARM[4] indicates if REQ is in mini-slots or ATM cells.<br>[4] = 0; mini-slot REQ.<br>[4] = 1; ATM cell REQ.<br>EHDR_ON = 0; no EHDR allowed. | 8 bits  |
+| MAC_PARM | REQ, total amount of bandwidth requested (upstream only):<br>if FC_PARM[4] = 0; REQ is number of mini-slots.<br>if FC_PARM[4] = 1; REQ is number of ATM cells.                                                                                         | 8 bits  |
+| SID      | Service ID (0 ...0x3FFF)                                                                                                                                                                                                                               | 16 bits |
+| EHDR     | Extended MAC Header not allowed                                                                                                                                                                                                                        | 0 bytes |
+| HCS      | MAC Header check sequence                                                                                                                                                                                                                              | 2 bytes |
+|          | Length of a REQ MAC Header                                                                                                                                                                                                                             | 6 bytes |
+
+### C.6.2.5.4 Concatenation
+
+In order to transmit multiple MAC frames by one burst, a specific MAC Header is defined.
+
+A concatenation MAC Header appears only once at the head of MAC Frame. It contains MAC Frame number(n) and then n MAC frames follow after the header as shown in Figure C.6-12.
+
+![Diagram of MAC Concatenation Frame structure. The frame consists of a PHY Overhead, a MAC Hdr (Concatenation), and a series of MAC Frames (MAC HDR + optional PDU). The first MAC frame is labeled MAC Frame 1 and the last is labeled MAC Frame n.](022d1dc5699c55186a08a897cad90392_img.jpg)
+
+The diagram shows the structure of a MAC Concatenation Frame. It consists of a PHY Overhead, a MAC Hdr (Concatenation), and a series of MAC Frames (MAC HDR + optional PDU). The first MAC frame is labeled MAC Frame 1 and the last is labeled MAC Frame n.
+
+Diagram of MAC Concatenation Frame structure. The frame consists of a PHY Overhead, a MAC Hdr (Concatenation), and a series of MAC Frames (MAC HDR + optional PDU). The first MAC frame is labeled MAC Frame 1 and the last is labeled MAC Frame n.
+
+Figure C.6-12/J.112 – MAC Concatenation Frame
+
+MAC Concatenation Header should allow any type of MAC Frame to enable mixture use of Packet, reserved PDU and MAC-specific frame (see Figure C.6-13 and Table C.6-7).
+
+![Diagram of MAC Concatenation Header structure. The top row shows four fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), and HCS (2 bytes). Below the FC field, a dashed line points to a breakdown of its 8 bits: FC_TYPE = 11, FC_PARM = 11100, and EHDR_ON = 0. The diagram is labeled T0905400-97/d126.](c9e2a114dcd84c4d10e4f411ab1288a8_img.jpg)
+
+Diagram of MAC Concatenation Header structure. The top row shows four fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), and HCS (2 bytes). Below the FC field, a dashed line points to a breakdown of its 8 bits: FC\_TYPE = 11, FC\_PARM = 11100, and EHDR\_ON = 0. The diagram is labeled T0905400-97/d126.
+
+Figure C.6-13/J.112 – MAC Concatenation Header
+
+Tableau C.6-7/J.112 – MAC Concatenation Header format
+
+| Field       | Usage                                                                                                                                    | Size          |
+|-------------|------------------------------------------------------------------------------------------------------------------------------------------|---------------|
+| FC          | FC_TYPE = 11; MAC-specific Header.<br>FC_PARM[4:0] = 11100; Concatenation MAC Header.<br>EHDR_ON = 0; no EHDR with Concatenation Header. | 8 bits        |
+| MAC_PARM    | CNT, number of MAC frames in this concatenation.<br>CNT = 0 indicates unspecified number of MAC frames.                                  | 8 bits        |
+| LEN         | LEN = x + . . . + y; length of all following MAC frames in bytes.                                                                        | 16 bits       |
+| EHDR        | Extended MAC Header MUST NOT be used.                                                                                                    | 0 byte        |
+| HCS         | MAC Header check sequence                                                                                                                | 2 bytes       |
+| MAC frame 1 | First MAC frame: MAC Header plus OPTIONAL data PDU.                                                                                      | x bytes       |
+| MAC frame n | Last MAC frame: MAC Header plus OPTIONAL data PDU.                                                                                       | y bytes       |
+|             | Length of Concatenated MAC Frame                                                                                                         | 6 + LEN bytes |
+
+#### C.6.2.5.5 Extended header
+
+The MAC Frame, besides timing, concatenation MAC Header and request, should have an Extended MAC Header (EHDR) in order to send next reservation information as shown in Figure C.6-14 and Table C.6-8.
+
+![Diagram of Extended MAC Header structure. The top row shows six fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), EHDR (1-255 bytes), HCS (2 bytes), and HCS (2 bytes). Below the FC field, a dashed line points to a breakdown of its 8 bits: FC_TYPE = xx, FC_PARM (reserved), and EHDR_ON = 1. Below the EHDR field, a dashed line points to a breakdown of its structure: EH_TYPE (4 bits), EH_LEN (4 bits), EH_VALUE (0-15 bytes), and a 'repeat' indicator. The diagram is labeled T0905410-97/d127.](923c3bd3420f28b00798eed4f8eeacd1_img.jpg)
+
+Diagram of Extended MAC Header structure. The top row shows six fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), EHDR (1-255 bytes), HCS (2 bytes), and HCS (2 bytes). Below the FC field, a dashed line points to a breakdown of its 8 bits: FC\_TYPE = xx, FC\_PARM (reserved), and EHDR\_ON = 1. Below the EHDR field, a dashed line points to a breakdown of its structure: EH\_TYPE (4 bits), EH\_LEN (4 bits), EH\_VALUE (0-15 bytes), and a 'repeat' indicator. The diagram is labeled T0905410-97/d127.
+
+Figure C.6-14/J.112 – Extended MAC Header
+
+**Table C.6-8/J.112 – Extended MAC Header format**
+
+| Field    | Usage                                                                                                                                  | Size            |
+|----------|----------------------------------------------------------------------------------------------------------------------------------------|-----------------|
+| FC       | FC_TYPE = XX; applies to all MAC Headers.<br>FC_PARM[4:0] = XXXXX; dependent on FC_TYPE.<br>EHDR_ON = 1; EHDR present in this example. | 8 bits          |
+| MAC_PARM | ELEN = x; length of EHDR in bytes.                                                                                                     | 8 bits          |
+| LEN      | LEN = x + y; length of EHDR plus OPTIONAL data PDU in bytes.                                                                           | 16 bits         |
+| EHDR     | Extended MAC Header present in this example                                                                                            | x bytes         |
+| HCS      | MAC Header check sequence                                                                                                              | 2 bytes         |
+| PDU      | OPTIONAL data PDU                                                                                                                      | y bytes         |
+|          | Length of MAC Frame with EHDR                                                                                                          | 6 + x + y bytes |
+
+EHDR should contain multiple EH elements. Table C.6-9 shows the format of EH element that has variable length TLV (Type-Length-Value) format.
+
+**Table C.6-9/J.112 – Element format of EHDR**
+
+| EH element fields | Usage                 | Size       |
+|-------------------|-----------------------|------------|
+| EH_TYPE           | EH Element Type Field | 4 bits     |
+| EH_LEN            | Length of EH element  | 4 bits     |
+| EH_VALUE          | EH element data       | 0-15 bytes |
+
+Table C.6-10 shows the type of EH. The first eight EH elements are used between MC and MH. The next seven elements are for MAC sublayer domain, that means in between MC and MH or in between MHs.
+
+**Table C.6-10/J.112 – EH element format**
+
+| EH_TYPE | EH_LEN | EH_VALUE                                                                                                                                    |
+|---------|--------|---------------------------------------------------------------------------------------------------------------------------------------------|
+| 0       | 0      | Null configuration setting; may be used to pad the extended header. The EH_LEN MUST be zero, but the configuration setting may be repeated. |
+| 1       | 3      | Request: mini-slots requested (1 byte);<br>SID (2 bytes) [MH → MC].                                                                         |
+| 2       | 2      | Acknowledgment requested; SID (2 bytes) [MH → MC].                                                                                          |
+| 3-7     |        | Reserved [MH → MC]                                                                                                                          |
+| 8       | 4      | Virtual LAN tag [MH ↔ MH]                                                                                                                   |
+| 10-14   |        | Reserved [MH ↔ MH]                                                                                                                          |
+| 15      | XX     | Extended EH element: EHX_TYPE (1 byte), EHX_LEN (1 byte), EH_VALUE.<br>(length determined by EHX_LEN)                                       |
+
+### C.6.2.6 MAC Frame error handling
+
+When an error occurs in upstream or downstream, that error may be detected by the Header Check Sequence (HCS). In the case of downstream errors, no specific process is required as the framing recovery is done by MPEG TC layer automatically and the MAC layer disposes of that erroneous frame. For an upstream error, the erroneous frame should be simply discarded and the next frame should start synchronization from the top of frame.
+
+### C.6.3 MAC Management message
+
+The MAC management message is the message for MAC access control or initialization, and forms a kernel of the entire MAC control. All the MAC management messages should be encapsulated into LLC frames and be transmitted with MAC-specific header as shown in Figure C.6-15 and Table C.6-11. Table C.6-12 classifies MAC management messages.
+
+![Diagram of MAC management message structure showing fields like FC, MAC_PARM, LEN, HCS, DA, SA, Msg LEN, DSAP, SSAP, Control, Version, Type, RSVD, Management message payload, and CRC. Bit positions 0, 8, 16, 24, 31 are indicated at the top. Labels 'MAC Header' and 'MAC management header' are on the right with arrows pointing to their respective sections.](7aeb1d06016b3a52a1d68ed9518dbbf4_img.jpg)
+
+The diagram illustrates the structure of a MAC management message. At the top, bit positions 0, 8, 16, 24, and 31 are marked. The first row of fields contains FC (bits 0-7), MAC\_PARM (bits 8-15), and LEN (bits 16-31). Below this is the HCS field. The next section is the MAC management header, which includes DA (Destination Address), SA (Source Address), Msg LEN (Message Length), DSAP, SSAP, Control, Version, Type, and RSVD. The final part is the Management message payload, followed by a CRC. On the right, a label 'MAC Header' with an upward arrow points to the top section, and a label 'MAC management header' with an upward arrow points to the middle section. A dashed line separates the top section from the rest. A code 'T0905420-97/d128' is at the bottom right.
+
+Diagram of MAC management message structure showing fields like FC, MAC\_PARM, LEN, HCS, DA, SA, Msg LEN, DSAP, SSAP, Control, Version, Type, RSVD, Management message payload, and CRC. Bit positions 0, 8, 16, 24, 31 are indicated at the top. Labels 'MAC Header' and 'MAC management header' are on the right with arrows pointing to their respective sections.
+
+Figure C.6-15/J.112 – MAC management message
+
+Table C.6-11/J.112 – MAC Management message format
+
+| Field                      | Usage                                                                                                            | Size            |
+|----------------------------|------------------------------------------------------------------------------------------------------------------|-----------------|
+| FC, MAC_PARM, LEN, HCS     | Common MAC Frame Header. All messages use a MAC-specific header.                                                 |                 |
+| Destination Address (DA)   | MAC management frames will be addressed to a specific MH unicast address or to the management multicast address. | 6 bytes         |
+| Source Address (SA)        | The MAC address of the source MH or MC system                                                                    | 6 bytes         |
+| Msg Length                 | The total length of the MAC message from DA to CRC inclusive                                                     | 2 bytes         |
+| DSAP                       | The LLC null SAP (00) as defined by [ISO/IEC 8802-2]                                                             | 1 byte          |
+| SSAP                       | The LLC null SAP (00) as defined by [ISO/IEC 8802-2]                                                             | 1 byte          |
+| Control                    | Unnumbered information frame (03) as defined by [ISO/IEC 8802-2]                                                 | 1 byte          |
+| Version                    | This field defines the version of the MAC management protocol in use. Set to 1 for this version.                 | 1 byte          |
+| Type                       | This field defines the type of this particular MAC management message.                                           | 1 byte          |
+| RSVD                       | This field is used to align the message payload on a 32-bit boundary. Set to 0 for this version.                 | 1 byte          |
+| Management Message Payload | As defined for each specific management message                                                                  | Variable length |
+| CRC                        | Covers message including header fields (DA, SA, ...). Polynomial defined by [ISO/IEC 8802-3].                    | 4 bytes         |
+
+**Table C.6-12/J.112 – MAC Management message classification**
+
+| Type value | Message name | Message description              |
+|------------|--------------|----------------------------------|
+| 1          | SYNC         | Timing synchronization           |
+| 2          | UCD          | Upstream channel descriptor      |
+| 3          | MAP          | Upstream bandwidth allocation    |
+| 4          | RNG-REQ      | Ranging Request                  |
+| 5          | RNG-RSP      | Ranging Response                 |
+| 6          | REG-REQ      | Registration Request             |
+| 7          | REG-RSP      | Registration Response            |
+| 8          | UCC-REQ      | Upstream channel change Request  |
+| 9          | UCC-RSP      | Upstream channel change Response |
+| 10-255     |              | Reserved for future use          |
+
+**C.6.3.1 Time synchronization**
+
+The Synchronization (SYNC) message should be transmitted periodically and simultaneously to MHs from MC to synchronize within the MAC sublayer. Figure C.6-16 depicts the format. The MC timestamp is a 32-bit timestamp based on the timebase reference clock.
+
+![Diagram of a 32-bit SYNC message structure. It shows a 'MAC Management Header' occupying the first 32 bits (bits 0 to 31) and an 'MC Timestamp' occupying the next 32 bits. Bit markers are shown at 0, 8, 16, 24, and 31.](ed433287faf6ca3f88eaaf14968986d6_img.jpg)
+
+Diagram of a 32-bit SYNC message structure. It shows a 'MAC Management Header' occupying the first 32 bits (bits 0 to 31) and an 'MC Timestamp' occupying the next 32 bits. Bit markers are shown at 0, 8, 16, 24, and 31.
+
+T0905430-97/d129
+
+**Figure C.6-16/J.112 – SYNC Message**
+
+**C.6.3.2 Upstream Channel Descriptor**
+
+MC should periodically transmit the Upstream Channel Descriptor (UCD) to notify upstream channel parameters. UCD contains a common parameter such as symbol rate or mini-slot size and multiple burst descriptors. A burst descriptor should contain several parameters of modulation method and FEC code length in accordance with MAC Frame.
+
+Figure C.6-17 shows a format of UCD which contains one header and multiple TLV type parameters, Table C.6-13 classifies UCD message formats.
+
+![Diagram of a 32-bit UCD message structure. It shows a 'MAC Management Header' occupying the first 32 bits (bits 0 to 31). Below the header, the message is divided into four sections: 'Upstream channel ID', 'Configuration Change Count', 'Mini-Slot Size', and 'Downstream channel ID' (bits 0-31); 'TLV-encoded information for the overall channel'; 'TLV-encoded Burst Description'; and 'TLV-encoded information for the subsequent burst descriptors'. Bit markers are shown at 0, 8, 16, 24, and 31.](e94f8f1631cc515867e8c0ebd1bac7fe_img.jpg)
+
+Diagram of a 32-bit UCD message structure. It shows a 'MAC Management Header' occupying the first 32 bits (bits 0 to 31). Below the header, the message is divided into four sections: 'Upstream channel ID', 'Configuration Change Count', 'Mini-Slot Size', and 'Downstream channel ID' (bits 0-31); 'TLV-encoded information for the overall channel'; 'TLV-encoded Burst Description'; and 'TLV-encoded information for the subsequent burst descriptors'. Bit markers are shown at 0, 8, 16, 24, and 31.
+
+T0905440-97/d130
+
+**Figure C.6-17/J.112 – UCD message**
+
+**Table C.6-13/J.112 – UCD Message format**
+
+| Field                      | Usage                                                                                                                                                                                                                                                                                                                                                            | Size   |
+|----------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|
+| Upstream channel ID        | The identifier of the upstream channel to which this message refers. This identifier is arbitrarily chosen by the MC and is only unique within the MAC-sublayer domain.                                                                                                                                                                                          | 1 byte |
+| Configuration Change Count | Incremented by one (modulo the field size) by the MC whenever any of the values of this channel descriptor change. If the value of this count in a subsequent UCD remains the same, the MH can quickly decide that the remaining fields have not changed, and may be able to disregard the remainder of the message. This value is also referenced from the MAP. | 1 byte |
+| Mini-Slot Size             | The size of the Mini-Slot for this upstream channel in units of the Timebase Tick (see SYNC message).                                                                                                                                                                                                                                                            | 1 byte |
+| Downstream channel ID      | The identifier of the downstream channel on which this message has been transmitted. This identifier is arbitrarily chosen by the MC and is only unique within the MAC-sublayer domain.                                                                                                                                                                          | 1 byte |
+
+Type 1-3 of Table C.6-14 shows common parameters for all MAC frames to be sent upstream. Type 4-burst descriptor is a set of physical parameters.
+
+**Table C.6-14/J.112 – UCD Message parameters**
+
+| Name             | Type (1 byte) | Length (1 byte) | Value (variable length)                                                                                                            |
+|------------------|---------------|-----------------|------------------------------------------------------------------------------------------------------------------------------------|
+| Symbol Rate      | 1             | 1               | 1-16 Multiples of base rate of 144 ksym/s                                                                                          |
+| Frequency        | 2             | 4               | Upstream center frequency (Hz)                                                                                                     |
+| Preamble Pattern | 3             | 1-128           | Preamble superstring. All burst-specific preamble values are chosen as bit-substrings of this string.                              |
+| Burst Descriptor | 4             |                 | May appear more than once; described below. The length is the number of bytes in the overall object, including embedded TLV items. |
+
+The burst descriptor, as shown in Figure C.6-18, is a set of composite information including TLV type objects. Length indicates byte number of the following data after interval usage code. Interval usage code is a descriptor of Physical Layer parameter set defined by each frame. Upon receipt of UCD, MH should pick up the burst descriptor information contained and record it. In the case of upstream bandwidth assignment, MC should assign interval usage code. MH should pick up the corresponding burst descriptor and set the physical layer parameters.
+
+![Diagram of Burst Descriptor format showing Type = 4 burst descriptor, Length 1-n, Interval Usage Code, and TLV codes for PHY parameters.](c7973a89da29a4a59561e36561984333_img.jpg)
+
+|                              |            |                        |
+|------------------------------|------------|------------------------|
+| Type = 4<br>burst descriptor | Length 1-n | Interval Usage<br>Code |
+| TLV codes for PHY parameters |            |                        |
+
+T0905950-97/d131
+
+Diagram of Burst Descriptor format showing Type = 4 burst descriptor, Length 1-n, Interval Usage Code, and TLV codes for PHY parameters.
+
+**Figure C.6-18/J.112 – Burst Descriptor format**
+
+Burst descriptor should accept unordered lists of physical layer attributes. Each attribute should be described in TLV format (see Table C.6-15).
+
+**Table C.6-15/J.112 – Burst Descriptor parameters**
+
+| Name                           | Type (1 byte) | Length (1 byte) | Value (variable length)                                                                                                                                                                                                                                                                                                                                                                                                                              |
+|--------------------------------|---------------|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Modulation Type                | 1             | 1               | 1 = QPSK                                                                                                                                                                                                                                                                                                                                                                                                                                             |
+| Differential Encoding          | 2             | 1               | 1 = on<br>2 = off                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+| Preamble Length                | 3             | 2               | Up to 1024 bits. The value must be an integral number of symbols (a multiple of 2 for QPSK).                                                                                                                                                                                                                                                                                                                                                         |
+| Preamble Value Offset          | 4             | 2               | Identifies the bits to be used for the preamble value. This is specified as a starting offset into the Preamble Pattern (see Table C.6-14). That is, a value of zero means that the first bit of the preamble for this burst type is the value of the first bit of the Preamble Pattern. A value of 100 means that the preamble is to use the 101st and succeeding bits from the Preamble Pattern. This value must be a multiple of the symbol size. |
+| FEC Error Correction (T bytes) | 5             | 1               | 0-10 bytes. Zero implies no Forward Error Correction.                                                                                                                                                                                                                                                                                                                                                                                                |
+| FEC Codeword Length (k)        | 6             | 1               | Fixed: 1 to 255<br>Shortened: 16 to 255                                                                                                                                                                                                                                                                                                                                                                                                              |
+| Scrambler Seed                 | 7             | 2               | The 15-bit seed value.                                                                                                                                                                                                                                                                                                                                                                                                                               |
+| Maximum Burst Size             | 8             | 1               | The maximum number of mini-slots that can be transmitted during this burst type. Absence of this configuration setting implies that the burst size is limited elsewhere. This value MUST be used when the interval type is Short Data Grant.                                                                                                                                                                                                         |
+| Guard Time Size                | 9             | 1               | Number of symbol times which must follow the end of this burst. (Although this value may be derivable from other network and architectural parameters, it is included here to ensure that the MHs and MC all use the same value.)                                                                                                                                                                                                                    |
+| Last Codeword Length           | 10            | 1               | 1 = fixed<br>2 = shortened                                                                                                                                                                                                                                                                                                                                                                                                                           |
+| Scrambler on/off               | 11            | 1               | 1 = on<br>2 = off                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+
+|        |              |                         |  |  |
+|--------|--------------|-------------------------|--|--|
+| Type 1 | Length 1     | Symbol Rate             |  |  |
+| Type 2 | Length 4     | Frequency               |  |  |
+| Type 3 | Length 1-128 | Preamble Superstring    |  |  |
+| Type 4 | Length N     | First Burst Descriptor  |  |  |
+| Type 4 | Length N     | Second Burst Descriptor |  |  |
+| Type 4 | Length N     | Third Burst Descriptor  |  |  |
+| Type 4 | Length N     | Fourth Burst Descriptor |  |  |
+
+T0905960-97/d132
+
+**Figure C.6-19/J.112 – A Sample of Burst Descriptor coding**
+
+### C.6.3.3 Upstream bandwidth allocation map
+
+Upstream bandwidth allocation map (MAP) is a message for upstream channel bandwidth assignment conveyed from MC to MH. Figure C.6-20 shows the MAP message and Table C.6-16 its format.
+
+![Diagram of the MAP message structure. It shows a MAC Management Header at the top, followed by a row of four fields: Upstream Channel ID, UCD Count, Number of elements, and Reserved. Below this is a row for Alloc Start Time, then a row for Ack Time. The next row contains four fields: Ranging Back-off Start, Ranging Back-off End, Data Back-off Start, and Data Back-off End. The bottom section is labeled MAP Information Elements. There are curly braces on the left and right sides of the diagram, and a small code 'T0905450-97/d133' at the bottom right.](45ea58ce337aa5583b7d8adaeeb28279_img.jpg)
+
+Diagram of the MAP message structure. It shows a MAC Management Header at the top, followed by a row of four fields: Upstream Channel ID, UCD Count, Number of elements, and Reserved. Below this is a row for Alloc Start Time, then a row for Ack Time. The next row contains four fields: Ranging Back-off Start, Ranging Back-off End, Data Back-off Start, and Data Back-off End. The bottom section is labeled MAP Information Elements. There are curly braces on the left and right sides of the diagram, and a small code 'T0905450-97/d133' at the bottom right.
+
+Figure C.6-20/J.112 – MAP message
+
+Table C.6-16/J.112 – MAP message format
+
+| Field                    | Usage                                                                                                                        | Size    |
+|--------------------------|------------------------------------------------------------------------------------------------------------------------------|---------|
+| Upstream channel ID      | The identifier of the upstream channel to which this message refers                                                          | 1 byte  |
+| UCD Count                | Matches the value of the Configuration Change Count of the UCD which describes the burst parameters which apply to this map. | 1 byte  |
+| Number of Elements       | Number of information elements in the map                                                                                    | 1 byte  |
+| Reserved                 | Reserved field for alignment                                                                                                 | 1 byte  |
+| Alloc Start time         | Effective start time from MC initialization (in mini-slots) for assignments within this map                                  | 4 bytes |
+| Ack time                 | Latest time, from MC initialization, (mini-slots) processed in up-stream that generated a Grant, Grant Pending or Data Ack   | 4 bytes |
+| Ranging Back-off Start   | Initial back-off window for initial ranging contention, expressed as a power of two. Values range 0-15.                      | 1 byte  |
+| Ranging Back-off End     | Final back-off window for initial ranging contention, expressed as a power of two. Values range 0-15.                        | 1 byte  |
+| Data Back-off Start      | Initial back-off window for contention data and requests, expressed as a power of two. Values range 0-15.                    | 1 byte  |
+| Data Back-off End        | Final back-off window for contention data and requests, expressed as a power of two. Values range 0-15.                      | 1 byte  |
+| MAP information elements | Bandwidth assignment information                                                                                             |         |
+
+MAP information elements should be in the format shown in Figure C.6-21 and Table C.6-17.
+
+![Diagram showing the structure of MAP information element coding. It consists of a vertical stack of tables. The first table is for the 'First interval' with SID, IUC, and offset = 0. The second is for the 'Second interval' with SID, IUC, and offset. There is a break indicated by wavy lines. The next table is for the 'Last interval' with SID, IUC, and offset. This is followed by two 'End-of-list (Null IE)' entries: one with SID = 0, IUC = 7, offset = map length; and another with SID, IUC, offset = map length. Another break indicated by wavy lines. The final section is 'Acknowledgements and Deferrals', followed by a table with SID, IUC, and offset = map length. A small code 'T0905460-97/d134' is at the bottom right.](cd3dcf61c1ffdb1e63e10d4761f492fd_img.jpg)
+
+T0905460-97/d134
+
+Diagram showing the structure of MAP information element coding. It consists of a vertical stack of tables. The first table is for the 'First interval' with SID, IUC, and offset = 0. The second is for the 'Second interval' with SID, IUC, and offset. There is a break indicated by wavy lines. The next table is for the 'Last interval' with SID, IUC, and offset. This is followed by two 'End-of-list (Null IE)' entries: one with SID = 0, IUC = 7, offset = map length; and another with SID, IUC, offset = map length. Another break indicated by wavy lines. The final section is 'Acknowledgements and Deferrals', followed by a table with SID, IUC, and offset = map length. A small code 'T0905460-97/d134' is at the bottom right.
+
+**Figure C.6-21/J.112 – MAP information element coding**
+
+**Table C.6-17/J.112 – IE format**
+
+| Field                        | Usage                                           | Size    |
+|------------------------------|-------------------------------------------------|---------|
+| SID                          | Bandwidth and service class assign to MH        | 14 bits |
+| IUC (Information Usage Code) | Usage of assigned band (for request, for grant) | 4 bits  |
+| Offset                       | Indicate first offset value of mini-slot domain | 14 bits |
+
+Information Usage Code (IUC) indicates a usage of allocated bandwidth. The list of IUCs is given in Table C.6-18.
+
+#### C.6.3.4 Ranging Request
+
+Ranging Request (RNG-REQ) is a requirement for ranging to be sent from MH to MC. After receiving RNG-REQ, MC should start measurement of latency and signal level and notify its adjustment value to MH by Ranging Response (RNG-RSP) that is described in the following paragraph. Figure C.6-22 shows RNG-REQ message and Table C.6-19, RNG-REQ message format.
+
+**Table C.6-18/J.112 – Information elements**
+
+| IE Name                                                   | Information Usage Code (IUC) (4 bits) | SID (14 bits)       | Mini-slot Offset (14 bits)                                                                            |
+|-----------------------------------------------------------|---------------------------------------|---------------------|-------------------------------------------------------------------------------------------------------|
+| Request                                                   | 1                                     | Any                 | Starting offset of REQ region                                                                         |
+| REQ/Data (refer to Appendix B.1 for multicast definition) | 2                                     | Multicast           | Starting offset of IMMEDIATE Data region well-known multicasts define start intervals                 |
+| Initial Maintenance                                       | 3                                     | Broadcast/multicast | Starting offset of MAINT region (used in Initial Ranging)                                             |
+| Station Maintenance                                       | 4                                     | Unicast             | Starting offset of MAINT region (used in Periodic Ranging)                                            |
+| Short Data Grant                                          | 5                                     | Unicast             | Starting offset of Data Grant assignment; if inferred length = 0, then it is a Data Grant pending.    |
+| Long Data Grant                                           | 6                                     | Unicast             | Starting offset of Data Grant assignment; if inferred length = 0, then it is a Data Grant Pending.    |
+| Null IE                                                   | 7                                     | Zero                | Ending offset of the previous grant. Used to bound the length of the last actual interval allocation. |
+| Data Ack                                                  | 8                                     | Unicast             | MC sets to 0                                                                                          |
+| Reserved                                                  | 9-14                                  | Any                 | Reserved                                                                                              |
+| Expansion                                                 | 15                                    | Expanded IUC        | # of additional 32-bit words in this IE                                                               |
+
+![Diagram of RNG-REQ message format showing a 32-bit word structure. The top part is the MAC Management Header (bits 0-31). The bottom part is split into two fields: SID (bits 0-15) and Downstream channel ID (bits 16-31).](10dedc905646e219d866b9c66f68146c_img.jpg)
+
+The diagram illustrates the structure of an RNG-REQ message. It is a 32-bit word, with bits numbered 0, 8, 16, 24, and 31. The top portion, spanning all 32 bits, is labeled 'MAC Management Header'. Below this, the word is divided into two fields: 'SID' occupies the first 16 bits (0 to 15), and 'Downstream channel ID' occupies the remaining 16 bits (16 to 31). A small label 'T0905470-97/d135' is present in the bottom right corner of the diagram area.
+
+Diagram of RNG-REQ message format showing a 32-bit word structure. The top part is the MAC Management Header (bits 0-31). The bottom part is split into two fields: SID (bits 0-15) and Downstream channel ID (bits 16-31).
+
+**Figure C.6-22/J.112 – RNG-REQ message**
+
+**Table C.6-19/J.112 – RNG-REQ message format**
+
+| Field                 | Usage                                                                                                                                                        | Size    |
+|-----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------|---------|
+| SID                   | Initialization SID or assigned SID for periodic requests (this is a 16-bit field of which the lower 14 bits define the SID with bits 14,15 defined to be 0.) | 2 bytes |
+| Downstream Channel ID | The identifier of the downstream channel on which the MH received the UCD which described this upstream.                                                     | 1 byte  |
+
+### C.6.3.5 Ranging Response
+
+Ranging Response (RNG-RSP) is sent to MH from MC according to RNG-REQ message. RNG-RSP should indicate the values of timing or signal level to be adjusted at MH. Figure C.6-23 depicts RNG-RSP message, Table C.6-20 gives RNG-RSP message encodings.
+
+![Diagram of the RNG-RSP message structure. It shows a 32-bit word (bits 0 to 31). The top 16 bits (0-15) are the MAC Management Header. The next 8 bits (16-23) are split into 'SID from request' (bits 16-19) and 'Upstream channel ID' (bits 20-23). The bottom 8 bits (24-31) are 'TLV Encoded Information'. A label T0905480-97/d136 is at the bottom right.](4706a500dbc72fdedc9bee99d7c78df5_img.jpg)
+
+Diagram of the RNG-RSP message structure. It shows a 32-bit word (bits 0 to 31). The top 16 bits (0-15) are the MAC Management Header. The next 8 bits (16-23) are split into 'SID from request' (bits 16-19) and 'Upstream channel ID' (bits 20-23). The bottom 8 bits (24-31) are 'TLV Encoded Information'. A label T0905480-97/d136 is at the bottom right.
+
+Figure C.6-23/J.112 – RNG-RSP message
+
+Table C.6-20/J.112 – RNG-RSP message encodings
+
+| Name                         | Type (1 byte) | Length (1 byte) | Value (variable length)                                  |
+|------------------------------|---------------|-----------------|----------------------------------------------------------|
+| Timing Adjust                | 1             | 4               | TX timing offset adjustment (signed 16-bit)              |
+| Power Level Adjust           | 2             | 1               | TX Power offset adjustment (signed 8-bit, 1dB units)     |
+| Offset Frequency Adjust      | 3             | 2               | TX frequency offset adjustment (signed 16-bit, Hz units) |
+| Transmit Equalization Adjust | 4             | n               | TX equalization data – See details below                 |
+| Ranging Status               | 5             | 1               | 1 = continue, 2 = abort, 3 = success.                    |
+| Reserved                     | 6-255         | n               | Reserved for future use                                  |
+
+If equalization functionality is needed, the coefficients of the equalizer (Tap Values) should be sent as an RNG-RSP message. Figure C.6-24 shows general equalization coefficients, Figure C.6-25 is for equalizer tap location and Figure C.6-26 is for TLV parameter coding.
+
+|                                |                            |                                     |
+|--------------------------------|----------------------------|-------------------------------------|
+| Type 4                         | Length                     | Number of taps per symbol           |
+| Number of forward taps (N)     | Number of reverse taps (M) |                                     |
+| First coefficient $F_0$ (real) |                            | First coefficient $F_0$ (imaginary) |
+
+}} }
+
+|                                        |                                             |
+|----------------------------------------|---------------------------------------------|
+| Last coefficient $F_N$ (real)          | Last coefficient $F_N$ (imaginary)          |
+| First reverse coefficient $D_0$ (real) | First reverse coefficient $D_0$ (imaginary) |
+
+}} }
+
+|                                       |                                            |
+|---------------------------------------|--------------------------------------------|
+| Last reverse coefficient $D_M$ (real) | Last reverse coefficient $D_M$ (imaginary) |
+|---------------------------------------|--------------------------------------------|
+
+T0905490-97/d137
+
+Figure C.6-24/J.112 – Equalizer coefficients
+
+![Block diagram of an equalizer showing forward and reverse tap locations. The input enters from the left and is split into a series of forward taps (F0, F1, F2, F3, F4, F5, ..., FN) and reverse taps (DM, ..., D5, D4, D3, D2, D1, D0). Each tap is followed by a summer (+) that adds the tap output to the main signal path. The forward taps use delay elements (z^-1) and the reverse taps use delay elements (z^-1) in a feedback loop. The final output is labeled 'Equalizer output' and is shown entering a connector symbol.](a37f48ee0216856cd8fa51f11177fb7f_img.jpg)
+
+Block diagram of an equalizer showing forward and reverse tap locations. The input enters from the left and is split into a series of forward taps (F0, F1, F2, F3, F4, F5, ..., FN) and reverse taps (DM, ..., D5, D4, D3, D2, D1, D0). Each tap is followed by a summer (+) that adds the tap output to the main signal path. The forward taps use delay elements (z^-1) and the reverse taps use delay elements (z^-1) in a feedback loop. The final output is labeled 'Equalizer output' and is shown entering a connector symbol.
+
+T0905500-97/d138
+
+Figure C.6-25/J.112 – Equalizer tap location
+
+|        |          |                                                    |
+|--------|----------|----------------------------------------------------|
+| Type 1 | Length 4 | Timing adjust                                      |
+| Type 2 | Length 1 | Power adjust                                       |
+| Type 3 | Length 2 | Frequency adjust information                       |
+| Type 4 | Length x | x bytes of MH transmitter equalization information |
+| Type 5 | Length 1 | Ranging status                                     |
+
+T0905970-97/d139
+
+Figure C.6-26/J.112 – TLV Type parameter coding
+
+### C.6.3.6 Registration Request
+
+In the initialization, MH should receive a parameter file and set first operation parameters. Then MH should transmit a Registration Request (REG-REQ) to negotiate each parameter such as frequency assignment of upstream and downstream or supporting of optional function with MC. The REG-REQ message should also contain an SID request in accordance with service grade. Figures C.6-27 and C.6-28 show REG-REQ messages and an example of encoding, respectively.
+
+![Diagram of REG-REQ message structure showing MAC Management Header, SID, and TLV Encoded Information with bit positions 0, 8, 16, 24, 31.](47ab805b7e6a0b6eb9e379fd8da934fa_img.jpg)
+
+The diagram illustrates the structure of a REG-REQ message. It is a 32-bit word (bits 0 to 31). The first 16 bits (bits 0 to 15) are the MAC Management Header. The next 8 bits (bits 16 to 23) are the SID. The remaining 8 bits (bits 24 to 31) are TLV Encoded Information. The diagram shows the MAC Management Header and SID as solid rectangles, and the TLV Encoded Information as a dashed rectangle.
+
+Diagram of REG-REQ message structure showing MAC Management Header, SID, and TLV Encoded Information with bit positions 0, 8, 16, 24, 31.
+
+Figure C.6-27/J.112 – REG-REQ message
+
+|         |           |                                  |  |
+|---------|-----------|----------------------------------|--|
+| Type 1  | Length 4  | Downstream Frequency             |  |
+| Type 2  | Length 1  | Upstream channel                 |  |
+| Type 3  | Length 1  | Network access                   |  |
+| Type 4  | Length 28 | Service class definition class 1 |  |
+| Type 4  | Length 28 | Service class definition class 2 |  |
+|         |           |                                  |  |
+| Type 4  | Length 28 | Service class definition class n |  |
+| Type 5  | Length 6  | Modem capabilities               |  |
+| Type 12 | Length 4  | Modem IP address                 |  |
+| Type 8  | Length 3  | Vendor ID                        |  |
+| Type 43 | Length n  | n-bytes of vendor-specific data  |  |
+| Type 6  | Length 16 | MH message integrity check       |  |
+| Type 7  | Length 16 | MC message integrity check       |  |
+
+T0905980-97/d141
+
+Figure C.6-28/J.112 – A sample of REG-REQ encodings
+
+### C.6.3.7 Registration Response
+
+Registration Response (REG-RSP) is a message from MC to MH in response to an REG-REQ message. MC should allocate upstream/downstream frequency, optional supporting function and SID to MH. Figures C.6-29 and C.6-30 depict REG-RSP message and an example of encoding, respectively.
+
+![Diagram of REG-RSP message structure showing MAC Management Header, SID from corresponding RNG-REQ, Response, and TLV Encoded Information across 32 bits (0-31).](147bfd471cf5feef55178475cec58064_img.jpg)
+
+The diagram illustrates the structure of a REG-RSP message across 32 bits (0 to 31). The first 16 bits (0-15) are the MAC Management Header. The next 8 bits (16-23) are divided into two 4-bit nibbles: 'SID from corresponding RNG-REQ' (bits 16-19) and 'Response' (bits 20-23). The remaining 8 bits (24-31) are 'TLV Encoded Information'. A dashed line on the right indicates the end of the message. The text 'T0905520-97/d142' is at the bottom right.
+
+Diagram of REG-RSP message structure showing MAC Management Header, SID from corresponding RNG-REQ, Response, and TLV Encoded Information across 32 bits (0-31).
+
+Figure C.6-29/J.112 – REG-RSP message
+
+|                                                            |          |                                  |
+|------------------------------------------------------------|----------|----------------------------------|
+| Type 1                                                     | Length 7 | Service class definition class 1 |
+| Type 1                                                     | Length 7 | Service class definition class 2 |
+| (Dashed box indicating multiple service class definitions) |          |                                  |
+| Type 1                                                     | Length 7 | Service class definition class n |
+| Type 6                                                     | Length 6 | Modem capability                 |
+
+T0905530-97/d143
+
+Figure C.6-30/J.112 – A sample of REG-RSP encodings
+
+Service Class Data is a composite parameter consisted of multiple parameters. Each service parameter should include only one parameter related to one service class. Table C.6-21 shows an example of service class encoding.
+
+**Table C.6-21/J.112 – A sample of service class data encodings**
+
+| Type | Length | Value (sub)type | Length | Value | Description                              |
+|------|--------|-----------------|--------|-------|------------------------------------------|
+| 1    | 7      |                 |        |       | Service class data configuration setting |
+|      |        | 1               | 1      | 1     | Service class 1                          |
+|      |        | 2               | 2      | 123   | SID for this class                       |
+| 1    | 7      |                 |        |       | Service class data configuration setting |
+|      |        | 1               | 1      | 2     | Service class 2                          |
+|      |        | 2               | 2      | 244   | SID for this class                       |
+| 1    | 7      |                 |        |       | Service class data configuration setting |
+|      |        | 1               | 1      | n     | Service class n                          |
+|      |        | 2               | 2      | 345   | SID for this class                       |
+
+**C.6.3.8 Upstream Channel Change Request**
+
+Upstream Channel Change Request (UCC-REQ) should be transmitted to indicate the upstream channel change to MH from MC. Figure C.6-31 shows a format for a UCC-REQ message.
+
+![Diagram of UCC-REQ message structure showing a 32-bit MAC Management Header and an Upstream channel ID field. Bit positions 0, 8, 16, 24, and 31 are marked. The diagram is labeled T0906720-98/d144.](4778d9d7c0721f39c453edbe614ccf7d_img.jpg)
+
+The diagram illustrates the structure of a UCC-REQ message. It consists of a 32-bit MAC Management Header followed by an Upstream channel ID field. The bit positions 0, 8, 16, 24, and 31 are indicated at the top. The MAC Management Header is shown as a single block, and the Upstream channel ID is shown as a separate block below it. The diagram is labeled T0906720-98/d144.
+
+Diagram of UCC-REQ message structure showing a 32-bit MAC Management Header and an Upstream channel ID field. Bit positions 0, 8, 16, 24, and 31 are marked. The diagram is labeled T0906720-98/d144.
+
+**Figure C.6-31/J.112 – UCC-REQ message**
+
+**C.6.3.9 Upstream Channel Change Response**
+
+MH should transmit Upstream Channel Change Response (UCC-RSP) message to MC in response to a UCC-REQ message. After transmission of UCC-RSP, MH should change upstream channel. MH should ignore UCC-REQ in the case of upstream channel change. If UCC-REQ indicates that the current channel is in use, MH should return a UCC-RSP message to MC nevertheless. Figure C.6-32 shows a format for a UCC-RSP message.
+
+![Diagram of UCC-RSP message structure showing a 32-bit MAC Management Header and an Upstream channel ID field. Bit positions 0, 8, 16, 24, and 31 are marked. The diagram is labeled T0906730-98/d145.](02a799c1f5281fea2b73bdf67f128cff_img.jpg)
+
+The diagram illustrates the structure of a UCC-RSP message. It consists of a 32-bit MAC Management Header followed by an Upstream channel ID field. The bit positions 0, 8, 16, 24, and 31 are indicated at the top. The MAC Management Header is shown as a single block, and the Upstream channel ID is shown as a separate block below it. The diagram is labeled T0906730-98/d145.
+
+Diagram of UCC-RSP message structure showing a 32-bit MAC Management Header and an Upstream channel ID field. Bit positions 0, 8, 16, 24, and 31 are marked. The diagram is labeled T0906730-98/d145.
+
+**Figure C.6-32/J.112 – UCC-RSP message**
+
+
+
+## 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                                                                                            |
+| <b>Series J</b> | <b>Transmission of television, sound programme and other multimedia signals</b>                                                |
+| 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
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@@ -0,0 +1,254 @@
+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a globe with a lightning bolt striking across it, and the letters 'ITU' superimposed on the globe.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.113**
+
+(03/98)
+
+SERIES J: TRANSMISSION OF TELEVISION, SOUND  
+PROGRAMME AND OTHER MULTIMEDIA SIGNALS
+
+Interactive systems for digital television distribution
+
+---
+
+**Digital video broadcasting interaction  
+channel through the PSTN/ISDN**
+
+ITU-T Recommendation J.113
+
+(Previously CCITT Recommendation)
+
+---
+
+# ITU-T J-SERIES RECOMMENDATIONS
+
+# TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS
+
+|                                                                                                 |                    |
+|-------------------------------------------------------------------------------------------------|--------------------|
+| General Recommendations                                                                         | J.1–J.9            |
+| General specifications for analogue sound-programme transmission                                | J.10–J.19          |
+| Performance characteristics of analogue sound-programme circuits                                | J.20–J.29          |
+| Equipment and lines used for analogue sound-programme circuits                                  | J.30–J.39          |
+| Digital encoders for analogue sound-programme signals                                           | J.40–J.49          |
+| Digital transmission of sound-programme signals                                                 | J.50–J.59          |
+| Circuits for analogue television transmission                                                   | J.60–J.69          |
+| Analogue television transmission over metallic lines and interconnection with radio-relay links | J.70–J.79          |
+| Digital transmission of television signals                                                      | J.80–J.89          |
+| Ancillary digital services for television transmission                                          | J.90–J.99          |
+| Operational requirements and methods for television transmission                                | J.100–J.109        |
+| <b>Interactive systems for digital television distribution</b>                                  | <b>J.110–J.129</b> |
+| Transport of MPEG-2 signals on packetised networks                                              | J.130–J.139        |
+| Measurement of the quality of service                                                           | J.140–J.149        |
+| Digital television distribution through local subscriber networks                               | J.150–J.159        |
+
+*For further details, please refer to ITU-T List of Recommendations.*
+
+## **ITU-T RECOMMENDATION J.113**
+
+# **DIGITAL VIDEO BROADCASTING INTERACTION CHANNEL THROUGH THE PSTN/ISDN**
+
+## **Summary**
+
+This Recommendation describes the provision of return channel interaction protocols over PSTN and ISDN to, and independently of, digital TV broadcast systems.
+
+### **Source**
+
+ITU-T Recommendation J.113 was prepared by ITU-T Study Group 9 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 18th of March 1998.
+
+### **Keywords**
+
+Digital TV services, interaction channel, ISDN, PSTN.
+
+## 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 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.....                      | 1 |
+| 4   | Abbreviations.....                    | 1 |
+| 5   | Protocol stack and system models..... | 2 |
+| 5.1 | Protocol stack model .....            | 2 |
+| 5.2 | System model/overview.....            | 2 |
+| 6   | Interaction channel for PSTN.....     | 3 |
+| 6.1 | PSTN requirement.....                 | 3 |
+| 6.2 | PSTN interfaces requirement.....      | 3 |
+| 7   | Interaction channel for ISDN.....     | 3 |
+| 7.1 | ISDN requirement .....                | 3 |
+| 7.2 | ISDN interfaces requirement .....     | 3 |
+
+## **Introduction**
+
+This Recommendation is one of a series describing interactive digital TV services. This Recommendation describes the provision of return channel interaction protocols over PSTN and ISDN to, and independently of, digital TV broadcast systems. Other relevant Recommendations are J.110 which describes the basic principles and J.111 which describes protocols independent of the underlying physical and transport protocols of such services.
+
+## DIGITAL VIDEO BROADCASTING INTERACTION CHANNEL THROUGH THE PSTN/ISDN
+
+(Geneva, 1998)
+
+## 1 Scope
+
+This Recommendation describes the provision of return channel interaction protocols over PSTN and ISDN to, and independently of, digital TV broadcast systems. Other relevant Recommendations are J.110 [1] which describes the basic principles and J.111 [2] which describes the network independent return channel protocols.
+
+## 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 J.110 (1997), *Basic principles for a worldwide common family of systems for the provision of interactive television services.*
+- [2] ITU-T Recommendation J.111 (1998), *Network independent protocols for interactive systems.*
+- [3] ITU-T Recommendation I.3xx, *ISDN – Network aspects.*
+- [4] ITU-T Recommendations I.430, I.431, *ISDN – physical layer.*
+- [5] ITU-T Recommendation Q.921/I.441 (1997), *ISDN user-network interface – Data link layer specification.*
+- [6] ITU-T Recommendation Q.931/I.451 (1998), *ISDN user-network interface Layer 3 specification for basic call control.*
+- [7] ITU-T Recommendation G.960 (1993), *Access digital section for ISDN basic rate access.*
+- [8] ITU-T Recommendation G.961 (1993), *Digital transmission system on metallic local lines for ISDN basic rate access.*
+- [9] ITU-T Recommendation I.414 (1997), *Overview of Recommendations of Layer 1 for ISDN and B-ISDN customer accesses.*
+- [10] ITU-T Recommendation I.112 (1993), *Vocabulary of terms for ISDN.*
+
+## 3 Definitions
+
+The definitions in Recommendation J.110 [1] apply.
+
+## 4 Abbreviations
+
+The abbreviations in Recommendation J.110 [1] apply.
+
+## 5 Protocol stack and system models
+
+### 5.1 Protocol stack model
+
+The protocol stack model used for the purposes of this Recommendation consists of the following layers:
+
+**Physical layer:** where all the physical (electrical) transmission parameters are defined – network dependent.
+
+**Transport layer:** defines all the relevant data structures and communication protocols like data containers, etc. – network dependent.
+
+**Application layer:** is the interactive application software and runtime environments – network independent.
+
+See Figure 1.
+
+![Diagram titled 'Layer structure for generic system reference model'. It shows a vertical stack of four layers. From top to bottom: 'Proprietary layers' (enclosed in a dashed box), 'Higher medium layers', 'Access mechanism Packet Structure', and 'Modulation Channel Coding Freq. Range Filtering Equalization Power'. To the right of the stack, 'Network independent protocols' is labeled for the top two layers, and 'Network dependent protocols' is labeled for the bottom two layers. A small code 'T0906370-98/d01' is at the bottom right.](07b17a620c75522d53916a11e12d1bff_img.jpg)
+
+Layer structure for generic system reference model
+
+Proprietary layers
+
+Higher medium layers
+
+Access mechanism  
+Packet Structure
+
+Modulation  
+Channel Coding  
+Freq. Range  
+Filtering  
+Equalization  
+Power
+
+Network independent protocols
+
+Network dependent protocols
+
+T0906370-98/d01
+
+Diagram titled 'Layer structure for generic system reference model'. It shows a vertical stack of four layers. From top to bottom: 'Proprietary layers' (enclosed in a dashed box), 'Higher medium layers', 'Access mechanism Packet Structure', and 'Modulation Channel Coding Freq. Range Filtering Equalization Power'. To the right of the stack, 'Network independent protocols' is labeled for the top two layers, and 'Network dependent protocols' is labeled for the bottom two layers. A small code 'T0906370-98/d01' is at the bottom right.
+
+**Figure 1/J.113 – Layer structure for generic system reference model**
+
+This Recommendation describes the network dependent protocols within the transport and physical layers for the PSTN/ISDN. The network independent protocols are described in Recommendation J.111 [2] (to layer 4 of the OSI reference model typically).
+
+### 5.2 System model/overview
+
+Refer to Recommendation J.110 [1].
+
+## **6 Interaction channel for PSTN**
+
+### **6.1 PSTN requirement**
+
+The PSTN shall provide a bidirectional communication path between interfaces A<sub>x</sub> (PSTN/Interactive network adaptor interface) and A<sub>b</sub> (PSTN/Interactive interface module interface) of the system model of Figure 2/J.110 [1].
+
+### **6.2 PSTN interfaces requirement**
+
+Both the interactive network adaptor at interface A<sub>x</sub> and the interactive interface module at interface A<sub>b</sub> shall comply with the physical and transport layer functionality requirements relevant to the national PSTN service provider concerned.
+
+## **7 Interaction channel for ISDN**
+
+### **7.1 ISDN requirement**
+
+The ISDN shall provide a bidirectional communication path between interfaces A<sub>x</sub> (ISDN/Interactive network adaptor interface) and A<sub>b</sub> (ISDN/Interactive interface module interface) of the system model of Figure 2/J.110 [1]. For the purposes of this Recommendation, it is assumed that the ISDN complies with Recommendation I.3xx [3].
+
+### **7.2 ISDN interfaces requirement**
+
+The physical and transport layer functions of the interactive network adaptor at interface A<sub>x</sub> and the interactive interface module at interface A<sub>b</sub> shall comply with Recommendations I.430, I.431 [4], Q.921/I.441 [5], Q.931/I.451 [6], G.960 [7], G.961 [8], I.414 [9] and I.112 [10].
+
+
+
+# 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                                                                                            |
+| <b>Series J</b> | <b>Transmission of television, sound programme and other multimedia signals</b>                                                |
+| 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 communication                                                                                    |
+| Series Y        | Global information infrastructure                                                                                              |
+| Series Z        | Programming languages                                                                                                          |
\ No newline at end of file
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+
+
+![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
+
+**J.114**
+
+(09/99)
+
+SERIES J: TRANSMISSION OF TELEVISION, SOUND  
+PROGRAMME AND OTHER MULTIMEDIA SIGNALS
+
+Interactive systems for digital television distribution
+
+---
+
+**Interaction channel using digital enhanced  
+cordless telecommunications**
+
+ITU-T Recommendation J.114
+
+(Previously CCITT Recommendation)
+
+---
+
+# ITU-T J-SERIES RECOMMENDATIONS
+
+# **TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS**
+
+|                                                                                                 |                    |
+|-------------------------------------------------------------------------------------------------|--------------------|
+| General Recommendations                                                                         | J.1–J.9            |
+| General specifications for analogue sound-programme transmission                                | J.10–J.19          |
+| Performance characteristics of analogue sound-programme circuits                                | J.20–J.29          |
+| Equipment and lines used for analogue sound-programme circuits                                  | J.30–J.39          |
+| Digital encoders for analogue sound-programme signals                                           | J.40–J.49          |
+| Digital transmission of sound-programme signals                                                 | J.50–J.59          |
+| Circuits for analogue television transmission                                                   | J.60–J.69          |
+| Analogue television transmission over metallic lines and interconnection with radio-relay links | J.70–J.79          |
+| Digital transmission of television signals                                                      | J.80–J.89          |
+| Ancillary digital services for television transmission                                          | J.90–J.99          |
+| Operational requirements and methods for television transmission                                | J.100–J.109        |
+| <b>Interactive systems for digital television distribution</b>                                  | <b>J.110–J.129</b> |
+| Transport of MPEG-2 signals on packetised networks                                              | J.130–J.139        |
+| Measurement of the quality of service                                                           | J.140–J.149        |
+| Digital television distribution through local subscriber networks                               | J.150–J.159        |
+
+*For further details, please refer to ITU-T List of Recommendations.*
+
+# **ITU-T RECOMMENDATION J.114**
+
+# **INTERACTION CHANNEL USING DIGITAL ENHANCED CORDLESS TELECOMMUNICATIONS**
+
+## **Summary**
+
+This Recommendation is the baseline specification for the provision of an interaction channel using the Digital Enhanced Cordless Telecommunications (DECT) Standard in conjunction with a digital broadcasting delivery medium. It is suitable for use with any broadcast transmission medium, such as cable, satellite, terrestrial, etc., thus ensuring the maximum degree of interoperability and economies of scale.
+
+### **Source**
+
+ITU-T Recommendation J.114 was prepared by ITU-T Study Group 9 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on 16 September 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 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
+
+|                                                        | <i>Page</i> |
+|--------------------------------------------------------|-------------|
+| 1 Scope .....                                          | 1           |
+| 2 References .....                                     | 1           |
+| 2.1 Normative references .....                         | 1           |
+| 2.2 Informative references .....                       | 1           |
+| 3 Abbreviations.....                                   | 2           |
+| 4 Reference model.....                                 | 3           |
+| 4.1 Protocol stack model .....                         | 3           |
+| 4.2 System model.....                                  | 4           |
+| 5 DVB interaction channel specification for DECT ..... | 4           |
+| 5.1 System architecture .....                          | 5           |
+| 5.2 Physical interfaces.....                           | 5           |
+| 5.3 Calling procedures .....                           | 5           |
+| 5.4 DECT profiles .....                                | 5           |
+| 5.5 Forced disconnection .....                         | 7           |
+| Appendix I – Basic characteristics of DECT .....       | 7           |
+| I.1 DECT introduction.....                             | 7           |
+| I.2 DECT standard.....                                 | 8           |
+| I.3 Profiles .....                                     | 11          |
+| I.4 Wireless Relay Station (WRS).....                  | 14          |
+| I.5 DECT Authentication Module (DAM) .....             | 14          |
+| Appendix II – DECT implementation alternatives.....    | 15          |
+
+## **Introduction**
+
+This Recommendation, for the use of the DECT system to provide an interaction channel for a digital broadcasting service, is not transmission medium specific. It can be used with any of the broadcast transmission media currently standardized by the ITU. It is consistent with the generic reference model described in Recommendation J.110, and the network independent protocols in Recommendation J.111.
+
+# INTERACTION CHANNEL USING DIGITAL ENHANCED CORDLESS TELECOMMUNICATIONS
+
+(Geneva, 1999)
+
+# 1 Scope
+
+This Recommendation is the baseline specification for the provision of an interaction channel based on the Digital Enhanced Cordless Telecommunications (DECT) to Digital Video Broadcasting (DVB) systems.
+
+This Recommendation does not intend to specify an interaction channel solution associated to each broadcast system because the interoperability of different delivery media to transport the interaction channel is desirable. Therefore, the DECT solution for the interaction channel applies to satellite, cable, MATV, Satellite Master Antenna TeleVision (SMATV), terrestrial, microwave or any future DVB broadcasting or distribution system.
+
+The solutions provided in this Recommendation for an interaction channel through the DECT are a part of a wider set of alternatives to implement interactive services for DVB systems.
+
+# 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.
+
+## 2.1 Normative references
+
+- [1] ITU-T Recommendation J.110 (1997), *Basic principles for a worldwide common family of systems for the provision of interactive television services.*
+- [2] ITU-T Recommendation J.111 (1998), *Network independent protocols for interactive systems.*
+- [3] EN 50201:1998, *Interfaces for DVB-IRD*, CENELEC.
+- [4] ETS 300 765-2 (1998), *Digital Enhanced Cordless Telecommunications (DECT); Radio in the Local Loop (RLL) Access Profile (RAP); Part 2: Advanced telephony services.*
+- [5] EN 301 240 (1998), *Digital Enhanced Cordless Telecommunications (DECT); Data Services Profile (DSP); Point-to-Point Protocol (PPP) interworking for internet access and general multi-protocol datagram transport.*
+- [6] ETS 300 700 (1997), *Digital Enhanced Cordless Telecommunications (DECT); Wireless Relay Station (WRS).*
+
+## 2.2 Informative references
+
+- [7] ETS 300 765-1 (1997), *Digital Enhanced Cordless Telecommunications (DECT); Radio in the Local Loop (RLL) Access Profile (RAP); Part 1: Basic telephony services.*
+- [8] ETS 300 444 (1995), *Digital Enhanced Cordless Telecommunications (DECT); Generic Access Profile (GAP).*
+- [9] ETS 300 822 (1998), *Digital Enhanced Cordless Telecommunications (DECT); Integrated Services Digital Network (ISDN); DECT/ISDN Interworking for intermediate system configuration; Interworking and profile specification.*
+
+- [10] ETR 308 (1996), *Digital Enhanced Cordless Telecommunications (DECT); Services, facilities and configurations for DECT in the local loop.*
+- [11] ETR 185 (1995), *Digital Enhanced Cordless Telecommunications (DECT); Data Services Profile (DSP); Profile overview.*
+- [12] ETS 300 651 (1996), *Digital Enhanced Cordless Telecommunications (DECT); Data Services Profile (DSP); Generic data link service; (service type C, class 2).*
+- [13] ETS 300 701 (1996), *Digital Enhanced Cordless Telecommunications (DECT); Data Services Profile (DSP); Generic frame relay service with mobility (service types A and B, class 2).*
+
+# 3 Abbreviations
+
+This Recommendation uses the following abbreviations:
+
+|      |                                              |
+|------|----------------------------------------------|
+| A/V  | Audio/Video                                  |
+| BC   | Broadcast Channel                            |
+| CI   | Common Interface                             |
+| CTA  | Cordless Terminal Adapter                    |
+| DAM  | DECT Authentication Module                   |
+| DECT | Digital Enhanced Cordless Telecommunications |
+| DSP  | Data Services Profile                        |
+| EMC  | Electromagnetic Compatibility                |
+| FP   | Fixed Part                                   |
+| FT   | Fixed Termination                            |
+| GAP  | Generic Access Profile                       |
+| IC   | Interaction Channel                          |
+| IIM  | Interactive Interface Module                 |
+| IN   | Interactive Network                          |
+| INA  | Interactive Network Adapter                  |
+| IRD  | Integrated Receiver Decoder                  |
+| ISDN | Integrated Services Digital Network          |
+| IWU  | Inter-Working Unit                           |
+| LAP  | Link Access Protocol                         |
+| LLME | Lower Layer Management Entity                |
+| MAC  | Medium Access Control                        |
+| MATV | Master Antenna Television                    |
+| NIU  | Network Interface Unit                       |
+| NTU  | Network Termination Unit                     |
+| NWK  | Network                                      |
+| OSI  | Open Systems Interconnection                 |
+| PHL  | Physical                                     |
+| PP   | Portable Part                                |
+| PPP  | Point-to-Point Protocol                      |
+| PSTN | Public Switched Telephone Network            |
+| RAP  | Radio in the local loop Access Profile       |
+| RF   | Radio Frequency                              |
+
+|       |                                     |
+|-------|-------------------------------------|
+| RLL   | Radio in the Local Loop             |
+| SMATV | Satellite Master Antenna TeleVision |
+| STB   | Set-Top Box                         |
+| STU   | Set-Top Unit                        |
+| WRS   | Wireless Relay Station              |
+
+# 4 Reference model
+
+A reference model for the system architecture of narrow-band interaction channels in a broadband scenario (asymmetric interactive services) is presented in this clause. [1]
+
+## 4.1 Protocol stack model
+
+Within the Digital Video Broadcasting (DVB) commercial requirements for asymmetric interactive services supporting broadcast to the home with narrow-band return channel (see DVB-A008 [7]), a simple communications model has been used to identify the necessity and importance of each commercial requirement consisting of the following layers (the layers do not coincide exactly with the Open Systems Interconnection (OSI) layers):
+
+- *Physical layer*: where all the physical (electrical) transmission parameters are defined.
+- *Transport layer*: defines all the relevant data structures and communication protocols like data containers, etc.
+- *Application layer*: is the interactive application software and runtime environment (e.g. home shopping application, script interpreter, etc.).
+
+This Recommendation addresses the lower two layers (the physical and transport layers), leaving the application layer open to competitive market forces. A simplified model of the OSI layers was adopted to facilitate the production of specifications for these nodes. Figure 1 points out the lower layers of the simplified model and identifies some of the key parameters. Following the user requirements for interactive services, no attempt will be made to consider higher layers in this Recommendation.
+
+![Diagram of the layer structure for generic system reference model. It shows four stacked layers. The top two layers, 'Proprietary layers' and 'Higher medium layers', are enclosed in a dashed box labeled 'Network-independent protocols'. The bottom two layers, 'Access mechanism Packet structure' and a list of physical parameters (Modulation, Channel coding, Frequency range, Filtering, Equalization, Power), are enclosed in a dashed box labeled 'Network-dependent protocols'.](0b87abe67b21a93777287649c33e755d_img.jpg)
+
+|                                                                                       |                               |
+|---------------------------------------------------------------------------------------|-------------------------------|
+| Proprietary layers                                                                    | Network-independent protocols |
+| Higher medium layers                                                                  |                               |
+| Access mechanism<br>Packet structure                                                  | Network-dependent protocols   |
+| Modulation<br>Channel coding<br>Frequency range<br>Filtering<br>Equalization<br>Power |                               |
+
+Diagram of the layer structure for generic system reference model. It shows four stacked layers. The top two layers, 'Proprietary layers' and 'Higher medium layers', are enclosed in a dashed box labeled 'Network-independent protocols'. The bottom two layers, 'Access mechanism Packet structure' and a list of physical parameters (Modulation, Channel coding, Frequency range, Filtering, Equalization, Power), are enclosed in a dashed box labeled 'Network-dependent protocols'.
+
+T0907830-99/d01
+
+Figure 1/J.114 – Layer structure for generic system reference model
+
+This Recommendation addresses the Digital Enhanced Cordless Telecommunications (DECT) specific aspects only. The network-independent protocols are specified separately in Recommendation J.111 [2].
+
+## 4.2 System model
+
+Figure 2 shows the system model which is to be used within DVB for interactive services. In the system model, two channels are established between the service provider and the user:
+
+- a) *Broadcast Channel (BC)*: A unidirectional broadband BC including video, audio and data. BC is established from the service provider to the users. It may include the forward interaction path.
+- b) *Interaction Channel (IC)*: A bidirectional interaction channel is established between the service provider and the user for interaction purposes. It is formed by:
+  - *Return interaction path* (return channel): From the user to the service provider. It is used to make requests to the service provider or to answer questions. It is a narrow-band channel. Also commonly known as return channel.
+  - *Forward interaction path*: From the service provider to the user. It is used to provide some sort of information by the service provider to the user and any other required communication for the interactive service provision. It may be embedded into the broadcast channel. It is possible that this channel is not required in some simple implementations which make use of the BC for the carriage of data to the user.
+
+![Figure 2/J.114 – A generic system reference model for interactive systems. The diagram illustrates the flow of data and interaction between a Broadcast Service Provider, an Interactive Service Provider, a Broadcast Network Adapter, an Interactive Network Adapter, a Broadcasting Delivery Media cloud, an Interaction Network cloud, a Set-Top Box (STB), a Set-Top Unit (STU), a Network-Interface Unit (NIU), and an End User. The STB contains a Broadcast Interface Module (BIM) and an Interactive Interface Module (IIM). The BIM connects to the Broadcasting Delivery Media and the STU. The IIM connects to the Interaction Network and the STU. The STU connects to the End User. The NIU connects to the STU and the End User. The diagram is divided into three horizontal sections: 'Broadcast Channel (DVB Transmission Systems)' at the top, 'Interaction channel' in the middle, and 'Network-independent' at the bottom. The 'Forward Interaction path' is shown as a dashed line from the Broadcast Service Provider to the STU. The 'Return Interaction path' is shown as a dashed line from the STU to the Interactive Service Provider. The 'Interaction channels' are shown as solid lines between the Interaction Network and the IIM. The 'Can be external to STB' label is placed near the NIU.](e6df2733626a85205c1db682e6259c46_img.jpg)
+
+Figure 2/J.114 – A generic system reference model for interactive systems. The diagram illustrates the flow of data and interaction between a Broadcast Service Provider, an Interactive Service Provider, a Broadcast Network Adapter, an Interactive Network Adapter, a Broadcasting Delivery Media cloud, an Interaction Network cloud, a Set-Top Box (STB), a Set-Top Unit (STU), a Network-Interface Unit (NIU), and an End User. The STB contains a Broadcast Interface Module (BIM) and an Interactive Interface Module (IIM). The BIM connects to the Broadcasting Delivery Media and the STU. The IIM connects to the Interaction Network and the STU. The STU connects to the End User. The NIU connects to the STU and the End User. The diagram is divided into three horizontal sections: 'Broadcast Channel (DVB Transmission Systems)' at the top, 'Interaction channel' in the middle, and 'Network-independent' at the bottom. The 'Forward Interaction path' is shown as a dashed line from the Broadcast Service Provider to the STU. The 'Return Interaction path' is shown as a dashed line from the STU to the Interactive Service Provider. The 'Interaction channels' are shown as solid lines between the Interaction Network and the IIM. The 'Can be external to STB' label is placed near the NIU.
+
+Figure 2/J.114 – A generic system reference model for interactive systems
+
+The user terminal, here named Set-Top Box (STB), is formed by the:
+
+- a) Network Interface Unit (NIU), consisting of the:
+  - 1) Broadcast Interface Module (BIM);
+  - 2) Interactive Interface Module (IIM); and
+- b) Set-Top Unit (STU).
+
+The user terminal provides interfaces for both broadcast and interaction channels. The interface between the user terminal and the interaction network is via the IIM.
+
+# 5 DVB interaction channel specification for DECT
+
+A DECT infrastructure can support the implementation of the interaction channel for DVB broadcasting systems by providing a wireless bidirectional communication path between the user terminal and an infrastructure connecting to the service provider.
+
+The basic characteristics of DECT are described in Appendix I.
+
+## 5.1 System architecture
+
+The Interactive Interface Module (IIM) is implemented through a DECT Portable Part (PP) (see Figure 3). The DECT PP can be internal or external to the STB.
+
+![Figure 3/J.114 – System architecture when DECT is used as the interaction channel. The diagram shows two main signal paths. The top path is for broadcast: Broadcast Service Provider -> Broadcast Network Adapter -> Broadcasting Delivery Media (cloud) -> Set-Top Box (STB). The bottom path is for interactive services: Interactive Service Provider -> Interactive Network Adapter -> PSTN, ISDN or other DVB interaction network (cloud) -> DECT FP (containing IWU and DECT FT) -> DECT WRS -> DECT PP (IIM) inside the STB. The DECT PP (IIM) is connected to the Set-Top Unit (STU) inside the STB. A note indicates the DECT PP can be external to the STB. Reference T0907850-99/d03 is shown at the bottom right.](e9314c83043183351ed74908e9bf2f90_img.jpg)
+
+T0907850-99/d03
+
+Figure 3/J.114 – System architecture when DECT is used as the interaction channel. The diagram shows two main signal paths. The top path is for broadcast: Broadcast Service Provider -> Broadcast Network Adapter -> Broadcasting Delivery Media (cloud) -> Set-Top Box (STB). The bottom path is for interactive services: Interactive Service Provider -> Interactive Network Adapter -> PSTN, ISDN or other DVB interaction network (cloud) -> DECT FP (containing IWU and DECT FT) -> DECT WRS -> DECT PP (IIM) inside the STB. The DECT PP (IIM) is connected to the Set-Top Unit (STU) inside the STB. A note indicates the DECT PP can be external to the STB. Reference T0907850-99/d03 is shown at the bottom right.
+
+Figure 3/J.114 – System architecture when DECT is used as the interaction channel
+
+DECT is a wireless access technology, not a complete network or system. Therefore, DECT Fixed Parts (FP) are part of the interaction network. A DECT FP includes an Inter-Working Unit (IWU) which handles the interconnection of DECT with the Interactive Network Adapter (INA) via another interaction network.
+
+## 5.2 Physical interfaces
+
+The physical interfaces relate to how the DECT PP is connected to the STU, how the DECT FP is connected to other interaction networks and the wireless physical interfaces between DECT PP, DECT FP and DECT Wireless Relay Stations (WRS). The DECT profiles specify the physical interfaces for different services and applications (see 5.4).
+
+In the case of a DECT PP external to the STB, the DVB-IRD interfaces are described in EN 50201 [3].
+
+## 5.3 Calling procedures
+
+The signalling protocols are specified by the DECT profiles (see 5.4).
+
+## 5.4 DECT profiles
+
+The connection of DECT to different networks, the operation of the DECT air interface and the signalling protocols for specific services and applications are described in the DECT profiles. A DVB operator using DECT as the interaction channel should use DECT profiles. Several DECT profiles can be supported in a DECT system, which means that other profiles can be supported in parallel with the profile used to carry the DVB network-independent protocols for interactive services (see Recommendation J.111 [2]).
+
+The default implementations described in 5.4.1 and 5.4.2 are based on the Radio in the local loop Access Profile (RAP) (see ETS 300 765-2 [4]) and the Data Services Profile (DSP) PPP interworking (see EN 301 240 [5]). The RAP offers valuable operation and maintenance functions. DSP PPP interworking offers effective handling of data traffic and describes the interworking to different fixed networks. When accessing an external DECT infrastructure, RAP functions are used in combination with the DSP PPP interworking.
+
+Due to the flexible nature of the DECT standard, several other implementation possibilities exist. Some of the implementation alternatives are described in Appendix II.
+
+### 5.4.1 Recommended DECT profiles when the DECT infrastructure is external to the home
+
+The RAP (see ETS 300 765-1 [7] and ETS 300 765-2 [4]) describe how DECT is used in Radio in the Local Loop (RLL) scenarios.
+
+It is recommended that the IIM is represented by a DECT PP internal to the STB with a RAP Data service (see ETS 300 765-2 [4]) according to the DSP PPP interworking (see EN 301 240 [5]) implemented, when the interaction channel is through a DECT infrastructure, external to the home (see Figure 4).
+
+The DECT PP (IIM) communicates with a DECT RAP data service (DSP PPP interworking) infrastructure comprised of FPs and possible WRSs (see ETS 300 700 [6]).
+
+A WRS relays intelligently the DECT signals between DECT FPs and DECT PPs. This STB implementation should be the default implementation when DECT is used as the interaction channel in DVB.
+
+![Diagram illustrating the default implementation of an interaction channel through a DECT infrastructure external to the home. A DECT FP RAP data service (DSP PPP interworking) is connected to a DECT WRS. The DECT WRS is connected to an STB [DECT PP RAP data service (DSP PPP interworking) + STU]. The STB is connected to a radio and a TV. The DECT FP RAP data service (DSP PPP interworking) is connected to the DECT WRS via a dashed line. The DECT WRS is connected to the STB via a solid line. The STB is connected to the radio and TV via a solid line. The DECT RAP data service (DSP PPP interworking) is shown between the DECT FP and the DECT WRS.](7f17c430b9598e4d748a8041457810b3_img.jpg)
+
+The diagram shows three main components: a DECT FP RAP data service (DSP PPP interworking) on the left, a DECT WRS in the center, and an STB [DECT PP RAP data service (DSP PPP interworking) + STU] on the right. The STB is connected to a radio and a TV. The DECT FP is connected to the DECT WRS via a dashed line. The DECT WRS is connected to the STB via a solid line. The STB is connected to the radio and TV via a solid line. The DECT RAP data service (DSP PPP interworking) is shown between the DECT FP and the DECT WRS.
+
+Diagram illustrating the default implementation of an interaction channel through a DECT infrastructure external to the home. A DECT FP RAP data service (DSP PPP interworking) is connected to a DECT WRS. The DECT WRS is connected to an STB [DECT PP RAP data service (DSP PPP interworking) + STU]. The STB is connected to a radio and a TV. The DECT FP RAP data service (DSP PPP interworking) is connected to the DECT WRS via a dashed line. The DECT WRS is connected to the STB via a solid line. The STB is connected to the radio and TV via a solid line. The DECT RAP data service (DSP PPP interworking) is shown between the DECT FP and the DECT WRS.
+
+NOTE – A DECT PP, supporting a RAP data service (DSP PPP interworking), is implemented in the STB. The STB communicates either directly with an FP (dashed line) or via a WRS (unbroken line). The WRS can be located internal to the home.
+
+**Figure 4/J.114 – Default implementation of an interaction channel through a DECT infrastructure, external to the home**
+
+### 5.4.2 Recommended DECT profiles when the DECT infrastructure is internal to the home
+
+DECT can be used in the home as a wireless interface to a network. In Figure 5, a home DECT FP is connected to a fixed network interface and provides the STB with a wireless interaction channel. The DECT STB implementation is the same as when the DECT FP is external to the home. The DECT PP RAP data service (DSP PPP interworking) terminal should notice that the home FP does not support RAP features, and therefore not use the RAP procedures. This STB implementation should be the default implementations when DECT is used as the interaction channel in DVB.
+
+![Diagram illustrating the default implementation of an interaction channel through a DECT infrastructure internal to the home. On the left, a 'Home interface' unit is shown with four ports: DATA port, ISDN port, PSTN port, and a Home DECT FP DSP PPP interworking unit. This unit is connected to a 'DECT WRS' (Wireless Radio System) via a 'DECT DSP PPP interworking' unit. The 'DECT WRS' is connected to an 'STB [DECT PP RAP data service (DSP PPP interworking) + STU]' via a 'radio' and 'TV' unit. The 'STB' is connected to the 'Home DECT FP DSP PPP interworking' unit via a dashed line, indicating a direct connection. The 'STB' is also connected to the 'DECT WRS' via a solid line, indicating a connection via the WRS. The diagram is labeled T0907870-99/d05.](af7916c89a458fdab6c3f443217388ae_img.jpg)
+
+Diagram illustrating the default implementation of an interaction channel through a DECT infrastructure internal to the home. On the left, a 'Home interface' unit is shown with four ports: DATA port, ISDN port, PSTN port, and a Home DECT FP DSP PPP interworking unit. This unit is connected to a 'DECT WRS' (Wireless Radio System) via a 'DECT DSP PPP interworking' unit. The 'DECT WRS' is connected to an 'STB [DECT PP RAP data service (DSP PPP interworking) + STU]' via a 'radio' and 'TV' unit. The 'STB' is connected to the 'Home DECT FP DSP PPP interworking' unit via a dashed line, indicating a direct connection. The 'STB' is also connected to the 'DECT WRS' via a solid line, indicating a connection via the WRS. The diagram is labeled T0907870-99/d05.
+
+NOTE – A DECT PP, supporting a RAP data service (DSP PPP interworking), is implemented in the STB. The STB communicates either directly with an FP (dashed line) or via a WRS (unbroken line).
+
+**Figure 5/J.114 – Default implementation of an interaction channel through a DECT infrastructure, internal to the home**
+
+## 5.5 Forced disconnection
+
+In an implementation incorporating connections to the Public Switched Telephone Network (PSTN), the communication on the interaction channel should not block an emergency call attempt. The DECT profiles allow this functionality in several ways. If not implemented, the application should allow a forced disconnection in the case of an emergency call.
+
+# Appendix I
+
+## Basic characteristics of DECT
+
+### I.1 DECT introduction
+
+DECT is a general radio access technology that can be used by many different applications to connect to different telecommunication networks.
+
+DECT offers both telephony and data communication services to users within the coverage area. The system is based on a micro-cellular concept that provides low-power radio access between portable parts and DECT fixed parts at ranges up to a few kilometres.
+
+DECT equipment is commercially available.
+
+The basic technical characteristics of DECT are as follows:
+
+|                      |                                                                                                    |                                                                   |
+|----------------------|----------------------------------------------------------------------------------------------------|-------------------------------------------------------------------|
+| Frequency band:      | 1880 to 1900 MHz (extended frequency band is under investigation).                                 |                                                                   |
+| Carriers:            | $10 \times 1728$ MHz.                                                                              |                                                                   |
+| Carrier multiplex:   | TDMA (Time Division Multiple Access), 24 full slots per frame (which can form 12 duplex channels). |                                                                   |
+| Peak transmit power: | 250 mW.                                                                                            |                                                                   |
+| Modulation:          | GFSK (Gaussian Frequency Shift Keying), BT (Bandwidth Time product) = 0.5.                         |                                                                   |
+| Frame length:        | 10 ms.                                                                                             |                                                                   |
+| Basic duplexing:     | TDD (Time Division Duplex) using two slots on the same carrier.                                    |                                                                   |
+| Gross bit rate:      | 1152 kbit/s per carrier.                                                                           |                                                                   |
+| Net bit rates:       | 8 kbit/s                                                                                           | B-field (traffic) per half slot (unprotected mode);               |
+|                      | 6.4 kbit/s                                                                                         | B-field (traffic) per half slot (protected mode);                 |
+|                      | 32 kbit/s                                                                                          | B-field (traffic) per full slot (unprotected mode);               |
+|                      | 25.6 kbit/s                                                                                        | B-field (traffic) per full slot (protected mode);                 |
+|                      | 80 kbit/s                                                                                          | B-field (traffic) per double slot (unprotected mode);             |
+|                      | 64 kbit/s                                                                                          | B-field (traffic) per double slot (protected mode);               |
+|                      | 6.4 kbit/s                                                                                         | A-field (control/signalling) per half slot, slot and double slot. |
+
+DECT has features that could be suitable in an interactive DVB system.
+
+DECT can handle a lot of users in a small area (urban and suburban situation) and support a broad range of services.
+
+DECT has algorithms for authentication of both the base station and the terminal as well as a simple encryption scheme DECT Authentication Module [(DAM) card support].
+
+A Wireless Relay Station (WRS) can be used to extend the coverage.
+
+There is no need for traditional frequency planning as DECT uses dynamic channel selection.
+
+In the rest of this appendix, more information is provided concerning the main functionality of the DECT standard.
+
+### I.2 DECT standard
+
+The structure of the basic DECT standard (see ETS 300 175 parts 1 to 9) is based on the layered principles used in the ISO Open Systems Interconnection (OSI) model. The complete DECT Common Interface (CI) corresponds to the lower three layers of the ISO OSI model, but DECT defines four layers of protocol. These lower layers differ from the OSI model because the OSI model takes no account of either the uncertainties introduced by using radio transmissions at the physical layer or of the concept of handover.
+
+A structure of four layers is used for the signalling protocols as shown in Figure I.1.
+
+The top of the NWK layer corresponds to the top of the OSI layer 3. The intermediate boundaries have no OSI equivalent but for ease of understanding an approximate correspondence is given below:
+
+- OSI Layer 1: all of the PHL layer plus part of the MAC layer;
+- OSI Layer 2: most of the MAC layer plus all of the DLC;
+- OSI Layer 3: all of the NWK layer.
+
+![Diagram of the DECT layered structure showing OSI layers 1, 2, and 3 mapped to DECT layers: Physical Layer (PHL), Medium Access Control Layer (MAC), Data Link Control Layer (DLC), and Network Layer (NWK). It also shows the C-Plane and U-Plane management entities.](33ed1f9b27c7c21c797aa928b0f06851_img.jpg)
+
+The diagram illustrates the DECT layered structure mapped to the OSI model. At the top, a 'Lower Layer Management Entity' is shown, connected to 'C-Plane' and 'U-Plane' management. Below this, the layers are defined as follows:
+
+- OSI Layer 3:** Network Layer (NWK)
+- OSI Layer 2:** Data Link Control Layer (DLC) and Medium Access Control Layer (MAC)
+- OSI Layer 1:** Physical Layer (PHL)
+
+T0907880-99/d06
+
+Diagram of the DECT layered structure showing OSI layers 1, 2, and 3 mapped to DECT layers: Physical Layer (PHL), Medium Access Control Layer (MAC), Data Link Control Layer (DLC), and Network Layer (NWK). It also shows the C-Plane and U-Plane management entities.
+
+Figure I.1/J.114 – The DECT layered structure
+
+#### I.2.1 Physical (PHL) layer
+
+The physical layer divides the radio spectrum into the physical channels. This division occurs in two fixed dimensions, frequency and time. The frequency and time division uses Time Division Multiple Access (TDMA) operation on multiple RF carriers. Ten carriers are provided in the frequency band 1880 MHz to 1900 MHz.
+
+DECT also provides for possible extensions of the band to meet future demand. On each carrier the TDMA structure defines 24 time slots (when full slots are used) in a 10 ms frame, where each time slot may be used to transmit one self contained packet of data (see Figure I.2).
+
+![Diagram of the full slot framing structure showing a 10 ms TDMA frame divided into 24 timeslots, with a detailed view of a single slot containing Sync.-field, D-field, Z, and Guard-Space components.](9b6b5924b48bf2fd5f347f88f06f45b3_img.jpg)
+
+The diagram shows the framing structure for a TDMA frame and a single timeslot:
+
+- 1 TDMA frame = 24 timeslots (10 ms)**
+- The frame is divided into two directions: **to the subscriber** (timeslots 1-12) and **from the subscriber** (timeslots 1-12).
+- A detailed view of a **SLOT** shows the following components and durations:
+  - Sync.-field (32 bit)**: 28 μs (bits b0 to b31)
+  - D-field (388 bit)**: 340 μs (bits b31 to b423)
+  - Z**: 49 μs (bits b423 to b479)
+  - Guard-Space (56 bit)**: 49 μs
+- A further detail of the **D-Field** shows:
+  - A-field (64 bit)**: 56 μs
+  - B-field (320 bit)**: 278 μs
+  - X-field (4 bit)**: 3 μs
+  - Z-field (4 bit)**: 3 μs
+
+T0907890-99/d07
+
+Diagram of the full slot framing structure showing a 10 ms TDMA frame divided into 24 timeslots, with a detailed view of a single slot containing Sync.-field, D-field, Z, and Guard-Space components.
+
+Figure I.2/J.114 – Example of the full slot framing structure
+
+Each transmitted packet contains a synchronization field, together with control information, service information and error control.
+
+Each FP radio end point operates according to a local timing reference and the PHL is the responsible for transmitting packets of data under direct control of the MAC layer. Adjacent FPs may be synchronized. This provides some advantages, particularly in high traffic situations.
+
+#### **I.2.2 Medium Access Control (MAC) layer**
+
+The MAC layer performs two main functions. Firstly, it selects physical channels, and then establishes and releases connections on those channels. Secondly, it multiplexes (and demultiplexes) control information, together with higher layer information and error control information, into slot-sized packets.
+
+These functions are used to provide three independent services: a broadcast service, a connection oriented service and a connectionless service.
+
+The broadcast service is a special DECT feature: it multiplexes a range of broadcast information into a reserved field (the A-field), and this field appears as part of all active transmissions. The broadcast service is always transmitted in every cell (even in the absence of user traffic) on at least one physical channel. These "beacon" transmissions allow PPs to quickly identify all FPs that are within range, to select one, and to lock to it without requiring any portable transmissions.
+
+#### **I.2.3 Data Link Control (DLC) layer**
+
+The DLC layer is concerned with the provision of very reliable data links to the NWK layer. Many of the imperfections of the radio transmissions are already removed by the efforts of the MAC layer, and the DLC layer is designed to work closely with the MAC layer to provide higher levels of data integrity than can be provided by the MAC layer alone.
+
+The DECT layered model separates into two planes of operation at the DLC layer: the C-plane and the U-plane.
+
+The C-plane is common to all applications, and provides very reliable links for the transmission of internal control signalling and limited quantities of user information traffic. Full error control is provided with a balanced Link Access Protocol (LAP).
+
+The U-plane provides a family of alternative services, where each service is optimized to the particular need of a specific type of services. The simplest service is the transparent unprotected service used for speech transmission.
+
+Other services support circuit mode and packet mode data transmission, with varying levels of protection.
+
+#### **I.2.4 Network (NWK) layer**
+
+The NWK layer is the main signalling layer of the protocol. It adopts a similar style to the ISDN layer 3 protocol and offers a similar level of functions. The NWK layer operates using an exchange of messages between peer entities.
+
+The basic set of messages supports the establishment, maintenance and release of calls. Additional messages support a range of extended capabilities.
+
+The basic Call Control (CC) provides a circuit switched service selected from one of the range of DLC options.
+
+Other network layer services are Supplementary Services (SS), Connection-oriented Message Service (COMS), ConnectionLess Message Service (CLMS) and Mobility Management (MM). These services are arranged as independent entities, and a particular application can be realized using more than one.
+
+The MM is a particularly important group of services. This group contains the procedures that support the special cordless mobility of PPs, for example authentication and location registration.
+
+#### **I.2.5 Lower Layer Management Entity (LLME)**
+
+The LLME contains defined procedures that concern more than one layer. Most of these procedures have only local significance, and they are defined in general terms to allow for alternative implementations. The location of some selected LLME procedures is as follows:
+
+- |            |                                                                                                                                                                                                                                             |
+|------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| MAC layer: | Creation, maintenance and release of bearers, by activating and deactivating pairs of physical channels; physical channel management, including the choice of free physical channels and the assessment of the quality of received signals. |
+| DLC layer: | Connection management, which includes the establishment and release of connections in response to NWK layer demands; routing of C-plane and U-plane data to suitable connections.                                                           |
+| NWK layer: | Service negotiation and mapping.                                                                                                                                                                                                            |
+
+#### **I.2.6 Inter-Working Units (IWU)**
+
+Transport of the information to the end user requires additional layers of protocol. In general, an IWU will be required to provide the necessary interworking functions. This IWU plays a important role in defining the exact service that is provided, e.g. when interconnecting to other networks as the PSTN or the ISDN.
+
+### **I.3 Profiles**
+
+The basic DECT standard defines the operation of the DECT air interface and is very general. To achieve interoperability for specific applications, different profiles have been defined or are in progress of being defined, e.g. the Generic Access Profile (GAP), the DECT/ISDN interworking profiles, the DECT data services profiles, the DECT/GSM (Global System for Mobile communications) interworking profile and the DECT radio in the local loop access profile.
+
+A DECT profile standard is a chosen subset of the DECT CI standard for a specific application. It includes all requirements for interoperability for equipment from different manufacturers. If the CI standard has some ambiguity or lacks some provision, this is clarified or added in the profile standard. All defined features are process mandatory. This means that if a feature is used, it is used in a specified manner. Whether the provision of a feature is mandatory or optional is stated separately for FPs and PPs.
+
+#### **I.3.1 Radio in the local loop Access Profile (RAP)**
+
+Radio in the Local Loop (RLL) is also defined in the DECT standard. The RLL Access Profile (RAP) is standardized in two parts (see ETS 300 765-1 [7] and ETS 300 765-2 [4]).
+
+ETS 300 765-1 [7] handles PSTN, analogue leased lines and 64 kbit/s bearer service. It also provides for optional mobility features by supporting GAP PP subscriber terminals and Cordless Terminal Adapter (CTAs) with WRS GAP functionality. For documents relating to RLL (basic telephony via PSTN), see Figure I.3.
+
+The second part contains telecommunication services as offered by ISDN, contemporary non-voice band data services provided through for example a dedicated data port at the CTA, and support of digital leased lines. The provision of the mentioned services is not mandated by the second part of the standard, but if they are provided they shall be provided as defined. For documents relating to RLL (advanced telephony), see Figure I.4.
+
+An objective is to use as much as possible for the RLL from existing profiles: the GAP profile (see ETS 300 444 [8] DECT-ISDN Intermediate System as defined in ETS 300 822 [9]) the data profiles, e.g. A/B.2 as defined in ETS 300 701 [13] and C.2. Therefore, most of the RAP features refer to features defined in other profiles and only the necessary additional features are listed and explained in the RAP document.
+
+The DECT RLL services are examined in detail in ETR 308 [10]. This ETR identifies the basic wired analogue PSTN services that could be replaced by an RLL system, and also identifies that there are market opportunities for much more advanced services than are possible with today's standard telephones.
+
+![Diagram showing the relationship between various standards and a basic telephony system via PSTN. On the left, a list of ETS 300 175 parts (Overview, PHL, MAC, DLC, NWK, Identities, Security, Telephony, PAP) points to a central box containing ETS 300 444 GAP and ETS 300 765-1 RLL Access Profile (RAP). Above this central box is 'Standard(s) for PSTN terminal'. Below it are 'EMC standards' and 'PSTN standards'. Arrows point from these elements to icons on the right: a telephone, a base station, a mobile station (marked with a large X), and a cloud representing the PSTN network. A curved arrow also points from the bottom standards back to the central box. The code T0907900-99/d08 is at the bottom right.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg)
+
+The diagram illustrates the architectural stack for basic telephony via PSTN. On the left, the ETS 300 175 standard is broken down into parts: Overview, Part 2 (PHL), Part 3 (MAC), Part 4 (DLC), Part 5 (NWK), Part 6 (Identities), Part 7 (Security), Part 8 (Telephony), Part 9 (PAP), and PAP. These parts feed into the central 'ETS 300 444 GAP' and 'ETS 300 765-1 RLL Access Profile (RAP)' block. Above this block is the 'Standard(s) for PSTN terminal'. Below are 'EMC standards' and 'PSTN standards'. Arrows indicate the flow from these standards to the physical components on the right: a PSTN terminal (telephone), a base station, a mobile station (which is crossed out with a large X, indicating it is not used in this configuration), and the PSTN network cloud. A curved arrow points from the bottom standards back to the central RLL Access Profile block. The code T0907900-99/d08 is located at the bottom right of the diagram.
+
+Diagram showing the relationship between various standards and a basic telephony system via PSTN. On the left, a list of ETS 300 175 parts (Overview, PHL, MAC, DLC, NWK, Identities, Security, Telephony, PAP) points to a central box containing ETS 300 444 GAP and ETS 300 765-1 RLL Access Profile (RAP). Above this central box is 'Standard(s) for PSTN terminal'. Below it are 'EMC standards' and 'PSTN standards'. Arrows point from these elements to icons on the right: a telephone, a base station, a mobile station (marked with a large X), and a cloud representing the PSTN network. A curved arrow also points from the bottom standards back to the central box. The code T0907900-99/d08 is at the bottom right.
+
+**Figure I.3/J.114 – Documents relating to RLL (basic telephony via PSTN)**
+
+#### I.3.2 Data Services Profiles (DSP)
+
+The DECT standard includes data services. The services and relationships of the different profiles are described in ETR 185 [11]. The DSP are a family of profiles which build upon and extend each other, aimed at the general connection of terminals supporting non-voice services to a fixed infrastructure, private and public. The application decides which type to use, due to parameters such as data rate, latency, reliability and power consumption. They all exploit the powerful lower-layer data services of DECT, which are specifically oriented towards LAN, multimedia and serial data capability, but each member of the profile family has been optimized for a different kind of user service. The DSP are divided into six service types and two mobility classes:
+
+- Type A: Low-speed frame relay, with a net sustainable throughput of up to 24 kbit/s, optimized for bursty data, low power consumption and low complexity applications such as handportable equipment.
+- Type B: High-performance frame relay, with a net sustainable throughput of up to 552 kbit/s asymmetrically or 288 kbit/s symmetrically, optimized for high speed and low latency with bursty data. Equipment implementing the type B profile shall interoperate with type A equipment.
+- Type C: Non-transparent connection of data streams requiring Link Access Protocol (LAP) services, optimized for high reliability and low additional complexity. Type C builds upon the services offered by the type A/B profiles. Provision for a packet assembly/disassembly function for asynchronous data streams is also included.
+- Type D: Transparent and isochronous connection of synchronous data streams optimized for interworking applications requiring continuous data streams.
+- Type E: A short message transfer or paging service which may be unacknowledged or acknowledged.
+
+![Diagram showing the relationship between ETS 300 175 parts, ISDN IS standards, and various terminals and networks. On the left, a list of ETS 300 175 parts (Overview, PHL, MAC, DLC, NWK, Identities, Security, Telephony, PAP) is shown. Arrows point from these parts to a central box labeled 'ISDN IS' which contains 'ETS 300 765-2 RLL Access Profile (RAP)' and 'DATA Profile'. Below this are 'EMC standards' and 'Network standards'. Arrows point from the central box to various icons on the right: a fax machine, a laptop, a modem, a router, and a cloud labeled 'Network'. A large 'X' is drawn over the arrows pointing to the router and network cloud. A small code 'T0907910-99/d09' is at the bottom right.](9c6461e1e94afae4dec455e69a2ce152_img.jpg)
+
+The diagram illustrates the mapping of ETS 300 175 parts to ISDN IS standards and their application in various terminals and networks. On the left, a vertical list of ETS 300 175 parts is shown: Overview, PHL, MAC, DLC, NWK, Identities, Security, Telephony, and PAP. Arrows from these parts point to a central box labeled 'ISDN IS'. Inside this box, 'ETS 300 765-2 RLL Access Profile (RAP)' and 'DATA Profile' are highlighted. Below the 'ISDN IS' box are 'EMC standards' and 'Network standards'. Arrows point from the central box to various icons on the right: a fax machine, a laptop, a modem, a router, and a cloud labeled 'Network'. A large 'X' is drawn over the arrows pointing to the router and network cloud, indicating that these standards do not apply to those specific interfaces. A small code 'T0907910-99/d09' is located at the bottom right of the diagram.
+
+Diagram showing the relationship between ETS 300 175 parts, ISDN IS standards, and various terminals and networks. On the left, a list of ETS 300 175 parts (Overview, PHL, MAC, DLC, NWK, Identities, Security, Telephony, PAP) is shown. Arrows point from these parts to a central box labeled 'ISDN IS' which contains 'ETS 300 765-2 RLL Access Profile (RAP)' and 'DATA Profile'. Below this are 'EMC standards' and 'Network standards'. Arrows point from the central box to various icons on the right: a fax machine, a laptop, a modem, a router, and a cloud labeled 'Network'. A large 'X' is drawn over the arrows pointing to the router and network cloud. A small code 'T0907910-99/d09' is at the bottom right.
+
+**Figure I.4/J.114 – Documents relating to RLL (advanced telephony)**
+
+- Type F: An application profile specifically supporting teleservices, such as fax building upon the services offered by the type A/B and C profiles.
+- Class 1: Local area applications with pre-registered terminals.
+- Class 2: Roaming applications, both public and private.
+
+##### I.3.2.1 PPP interworking DSP
+
+The ETSI project DECT approved in June 1997 a DSP for PPP interworking for public enquiry (see EN 301 240 [5]), which builds upon ETS 300 651 [12] and ETS 300 701 [13].
+
+The reasons for the choice of the PPP interworking DSP (see EN 301 240 [5]) for DVB applications are that it offers interworking to PPP, which the DVB network-independent protocols (see Recommendation J.111 [2]) makes use of, and a reliable and effective handling of data traffic over the air interface. The PPP interworking DSP and Recommendation J.111 [2] make references to the PPP specifications. This means that there is a harmonized overlap, but the PPP specifications should only be implemented once. A reliable and effective handling of data traffic is important for DVB applications and results from the fact that the PPP interworking DSP builds upon the C.2 profile (Type C, mobility Class 2).
+
+The PPP interworking DSP specifies an interworking profile for non-voice equipment with roaming mobility, providing PPP transmission to allow dial-up Internet access and general multi-protocol datagram transport. PPP packet transfers on the DECT air interface are specified via a high efficient DECT packet transmission protocol. However, interworking to the fixed network may be via a number of interface protocols, including X.25, Frame Relay, ATM, and traditional circuit switched voiceband modem and ISDN connection.
+
+The profile is intended for roaming applications and so specifies mobility Class 2. It thus specifies the requirements on the Network layer Call Control and Mobility Management entities to provide full public services. This profile defines the specific requirements on the Physical (PHL), Medium Access Control (MAC), Data Link Control (DLC) and Network (NWK) layers of DECT. The standard also specifies Management Entity (ME) requirements and generic interworking conventions which ensure the efficient use of the DECT spectrum.
+
+### **I.4 Wireless Relay Station (WRS)**
+
+A WRS is a special DECT unit, combining elements of both PPs and FPs, that is capable of intelligently relaying DECT radio transmissions to extend the coverage area (see ETS 300 700 [6]). A PP does not distinguish between a WRS and an FP.
+
+### **I.5 DECT Authentication Module (DAM)**
+
+Access rights and other subscription related information can be loaded into a PP over the air, via a connector, or by inserting a chip card. To use a DAM card, a PP has to be provided with the DAM interface.
+
+DAM is a chip card that can be programmed with DECT identities and inserted into a DECT PP with an appropriate DAM card interface. It provides one method by which a DECT system operator can load user identities, access rights information, security parameters (authentication and cipher keys) into a PP.
+
+A DAM card can be used in conjunction with different profiles, i.e. it is not restricted to any particular application.
+
+The DAM card is compatible with the corresponding card in GSM [the Subscriber Identity Module (SIM)].
+
+# **Appendix II**
+
+## **DECT implementation alternatives**
+
+Several implementation alternatives are possible when DECT is used as the interaction channel, which are based on the facts that DECT is a flexible solution that can be adapted to several networks and cope with several different services. The DECT standard supports e.g. combined telephony/data implementations. In the default configuration described in clause 5, the RAP data service (DSP PPP interworking) has been chosen. In certain scenarios, other DECT STB implementations can be used.
+
+If a DECT STB is used as an access to the PSTN, the RAP (see ETS 300 765-1 [7]) or the GAP (see ETS 300 444 [8]) can be implemented in the IIM. The GAP implementation offers, however, a very limited data capability. If a DECT STB is used as an access to ISDN, the RAP (see ETS 300 765-2 [4]) or an ISDN profile can be implemented in the IIM.
+
+In Figure II.1, a multi-service scenario is shown where the DVB platform is supported in combination with other platforms. This scenario includes a Network Termination Unit (NTU) in the home. An NTU is a unit which should be considered to be a part of the Interaction Network. An NTU can include a DECT WRS and/or a DECT CTA.
+
+A DECT WRS offers the user mobility within the premises, which can be used to provide the STB with a wireless interface when a DECT PP is integrated in the STB.
+
+![Diagram of a DECT scenario with multi-service support. A Home NTU (containing DECT interface, DECT WRS, DECT CTA, and A/V distribution) is connected via a DECT RAP data service to an STB (DECT PP RAP data service + STU). The STB is connected to a radio and a TV. The Home NTU also receives Video and Audio and provides DECT RAP data service. The STB is connected to a list of Platforms: Telemetrics, Telecom, Internet, DVB Interactive A/V, and Analogue broadcast.](5b8a756d9a71c35f17db8bcb90b438a3_img.jpg)
+
+DVB Interactive A/V services, e.g.:
+
+- PPV (Pay Per View)
+- NVOD (Near Video-On-Demand)
+- VOD (Video-On-Demand)
+- Teleshopping
+
+Platforms:
+
+- Telemetrics
+- Telecom
+- Internet
+- DVB Interactive A/V
+- Analogue broadcast
+
+T0907920-99/d10
+
+Diagram of a DECT scenario with multi-service support. A Home NTU (containing DECT interface, DECT WRS, DECT CTA, and A/V distribution) is connected via a DECT RAP data service to an STB (DECT PP RAP data service + STU). The STB is connected to a radio and a TV. The Home NTU also receives Video and Audio and provides DECT RAP data service. The STB is connected to a list of Platforms: Telemetrics, Telecom, Internet, DVB Interactive A/V, and Analogue broadcast.
+
+Figure II.1/J.114 – DECT scenario with multi-service support
+
+A DECT Cordless Terminal Adapter (CTA) offers the possibility to connect different kinds of equipment to physical interface ports, e.g. a PSTN port, an ISDN port, a LAN (Ethernet, Token Ring) port or a serial link (RS-232, Universal Serial Bus) port. A DECT CTA port can be used to connect an STB using a physical interface supported by the DECT CTA and the STB. The IIM is in this case external to the STB and is represented by the DECT CTA.
+
+
+
+# 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                                                                                            |
+| <b>Series J</b> | <b>Transmission of television, sound programme and other multimedia signals</b>                                                |
+| 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                                                           |
\ No newline at end of file
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.122**
+
+(12/2007)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Interactive systems for digital television distribution
+
+---
+
+**Second-generation transmission systems for  
+interactive cable television services – IP cable  
+modems**
+
+Recommendation ITU-T J.122
+
+
+
+# **Recommendation ITU-T J.122**
+
+# **Second-generation transmission systems for interactive cable television services – IP cable modems**
+
+## **Summary**
+
+This Recommendation describes transmission systems that are consistent with those described in ITU-T Recommendation J.112. Its purpose is to provide a technology through which the demand for symmetrical services on cable networks can be met. This second-generation technology, while using the same RF channel, is backward compatible with that of ITU-T Recommendation J.112. It provides a significant increase in upstream channel capacity with wider channels, higher symbol rate and increased spectral efficiency. It provides for both Synchronous-CDMA and Advanced-TDMA coding and also adds higher order modulation capabilities. It is more robust with regard to noise immunity and provides greater multipath protection than the technology used in ITU-T Recommendation J.112.
+
+## **Source**
+
+Recommendation ITU-T J.122 was approved on 14 December 2007 by ITU-T Study Group 9 (2005-2008) under 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 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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 and purpose .....                               | 1    |
+| 1.1 | Scope .....                                           | 1    |
+| 1.2 | Requirements .....                                    | 1    |
+| 1.3 | Background .....                                      | 2    |
+| 1.4 | Conventions for this Recommendation .....             | 4    |
+| 2   | References .....                                      | 4    |
+| 2.1 | Normative references .....                            | 4    |
+| 2.2 | Informative references .....                          | 6    |
+| 3   | Glossary .....                                        | 7    |
+| 3.1 | Abbreviations and acronyms .....                      | 7    |
+| 3.2 | Terms and definitions .....                           | 9    |
+| 4   | Functional assumptions .....                          | 17   |
+| 4.1 | Broadband access network .....                        | 17   |
+| 4.2 | Equipment assumptions .....                           | 18   |
+| 4.3 | RF channel assumptions .....                          | 18   |
+| 4.4 | Transmission levels .....                             | 20   |
+| 4.5 | Frequency inversion .....                             | 21   |
+| 5   | Communication protocols .....                         | 21   |
+| 5.1 | Protocol stack .....                                  | 21   |
+| 5.2 | The MAC forwarder .....                               | 25   |
+| 5.3 | Network layer .....                                   | 27   |
+| 5.4 | Above the network layer .....                         | 29   |
+| 5.5 | Data link layer .....                                 | 30   |
+| 5.6 | Physical layer .....                                  | 30   |
+| 6   | Physical media dependent sublayer specification ..... | 31   |
+| 6.1 | Scope .....                                           | 31   |
+| 6.2 | Upstream .....                                        | 31   |
+| 6.3 | Downstream .....                                      | 88   |
+| 7   | Downstream transmission convergence sublayer .....    | 94   |
+| 7.1 | Introduction .....                                    | 94   |
+| 7.2 | MPEG packet format .....                              | 95   |
+| 7.3 | MPEG header for DOCS data-over-cable .....            | 95   |
+| 7.4 | MPEG payload for DOCS data-over-cable .....           | 96   |
+| 7.5 | Interaction with the MAC sublayer .....               | 96   |
+| 7.6 | Interaction with the Physical Layer .....             | 98   |
+| 7.7 | MPEG header synchronization and recovery .....        | 98   |
+| 8   | Media access control specification .....              | 98   |
+| 8.1 | Introduction .....                                    | 98   |
+
+|                                                               | <b>Page</b> |
+|---------------------------------------------------------------|-------------|
+| 8.2 MAC frame formats .....                                   | 101         |
+| 8.3 MAC management messages .....                             | 121         |
+| 9 Media access control protocol operation .....               | 172         |
+| 9.1 Upstream bandwidth allocation .....                       | 172         |
+| 9.2 Support for multiple channels .....                       | 181         |
+| 9.3 Timing and synchronization .....                          | 181         |
+| 9.4 Upstream transmission and contention resolution .....     | 185         |
+| 9.5 Data link encryption support .....                        | 187         |
+| 10 Quality of service and fragmentation .....                 | 188         |
+| 10.1 Theory of operation .....                                | 188         |
+| 10.2 Upstream service flow scheduling services .....          | 203         |
+| 10.3 Fragmentation .....                                      | 207         |
+| 10.4 Payload header suppression .....                         | 214         |
+| 11 Cable modem – CMTS interaction .....                       | 221         |
+| 11.1 CMTS initialization .....                                | 221         |
+| 11.2 Cable modem initialization .....                         | 221         |
+| 11.3 Standard operation .....                                 | 243         |
+| 11.4 Dynamic service .....                                    | 250         |
+| 11.5 Fault detection and recovery .....                       | 309         |
+| 12 Supporting future new cable modem capabilities .....       | 310         |
+| 12.1 Downloading cable modem operating software .....         | 310         |
+| Annex A – Well-known addresses .....                          | 312         |
+| A.1 MAC addresses .....                                       | 312         |
+| A.2 MAC service IDs .....                                     | 312         |
+| A.3 MPEG PID .....                                            | 313         |
+| Annex B – Parameters and constants .....                      | 314         |
+| Annex C – Common radio frequency interface encodings .....    | 317         |
+| C.1 Encodings for configuration and MAC-layer messaging ..... | 317         |
+| C.2 Quality-of-service-related encodings .....                | 342         |
+| C.3 Encodings for other interfaces .....                      | 366         |
+| C.4 Confirmation code .....                                   | 367         |
+| Annex D – CM configuration interface specification .....      | 371         |
+| D.1 CM IP addressing .....                                    | 371         |
+| D.2 CM configuration .....                                    | 372         |
+| D.3 Configuration verification .....                          | 376         |
+| Annex E – The data-over-cable spanning tree protocol .....    | 378         |
+| E.1 Background .....                                          | 378         |
+| E.2 Public spanning tree .....                                | 378         |
+| E.3 Public spanning tree protocol details .....               | 379         |
+
+|                                                           | <b>Page</b> |
+|-----------------------------------------------------------|-------------|
+| E.4 Spanning tree parameters and defaults .....           | 380         |
+| Annex F – European specification additions .....          | 382         |
+| F.1 Scope and purpose .....                               | 382         |
+| F.2 References .....                                      | 382         |
+| F.3 Glossary .....                                        | 382         |
+| F.4 Functional assumptions .....                          | 382         |
+| F.5 Communication protocols .....                         | 385         |
+| F.6 Physical media dependent sublayer specification ..... | 386         |
+| F.7 Downstream transmission convergence sublayer .....    | 407         |
+| F.8 Media access control specification .....              | 408         |
+| Annex G – DOCS 2.0 and 1.0/1.1 interoperability .....     | 410         |
+| G.1 General interoperability issues .....                 | 410         |
+| G.2 Hybrid devices .....                                  | 413         |
+| G.3 DOCS 2.0 TDMA interoperability .....                  | 414         |
+| G.4 DOCS 2.0 S-CDMA interoperability .....                | 415         |
+| Annex H – The DOCS MAC/PHY interface (DMPI) .....         | 416         |
+| H.1 Scope .....                                           | 416         |
+| H.2 Conventions .....                                     | 416         |
+| H.3 Overview .....                                        | 417         |
+| H.4 Signals .....                                         | 420         |
+| H.5 Protocol .....                                        | 423         |
+| H.6 Electrical specifications .....                       | 428         |
+| H.7 Timing specifications .....                           | 428         |
+| H.8 Data format and usage .....                           | 430         |
+| Annex I – (Set aside) .....                               | 438         |
+| Annex J – Japan specification additions .....             | 438         |
+| J.1 Scope and purpose .....                               | 438         |
+| J.2 References .....                                      | 438         |
+| J.3 Glossary .....                                        | 438         |
+| J.4 Functional assumptions .....                          | 438         |
+| J.5 Communication protocols .....                         | 442         |
+| J.6 Physical media dependent sublayer specification ..... | 442         |
+| J.7 Downstream transmission convergence sublayer .....    | 465         |
+| J.8 Media access control specification .....              | 465         |
+| J.9 Media access control protocol operation .....         | 466         |
+| J.10 Quality of service and fragmentation .....           | 467         |
+| J.11 Cable modem – CMTS interaction .....                 | 467         |
+| J.C Common radio frequency interface encodings .....      | 467         |
+| J.E The data-over-cable spanning tree protocol .....      | 468         |
+
+|                                                                            | Page |
+|----------------------------------------------------------------------------|------|
+| Appendix I – MAC service definition.....                                   | 469  |
+| I.1    MAC service overview .....                                          | 469  |
+| I.2    MAC data service interface .....                                    | 471  |
+| I.3    MAC control service interface .....                                 | 473  |
+| I.4    MAC service usage scenarios.....                                    | 476  |
+| Appendix II – Example preamble sequence .....                              | 477  |
+| II.1   Introduction .....                                                  | 477  |
+| II.2   Example preamble sequence .....                                     | 477  |
+| Appendix III – Multiple upstream channels .....                            | 479  |
+| III.1  Single downstream and single upstream per cable segment .....       | 479  |
+| III.2  Multiple downstreams and multiple upstreams per cable segment ..... | 481  |
+| Appendix IV – DOCS transmission and contention resolution .....            | 485  |
+| IV.1   Introduction .....                                                  | 485  |
+| IV.2   Variable definitions .....                                          | 486  |
+| IV.3   State examples.....                                                 | 487  |
+| IV.4   Function examples.....                                              | 488  |
+| Appendix V – IGMP example .....                                            | 490  |
+| V.1    Events .....                                                        | 490  |
+| V.2    Actions.....                                                        | 491  |
+| Appendix VI – Unsolicited grant services .....                             | 492  |
+| VI.1   Unsolicited grant service (UGS) .....                               | 492  |
+| VI.2   Unsolicited grant service with activity detection (UGS-AD).....     | 494  |
+| Appendix VII – S-CDMA framing .....                                        | 498  |
+| VII.1  Coded subsymbol numbering.....                                      | 498  |
+| VII.2  Uncoded subsymbol numbering.....                                    | 498  |
+| VII.3  Framer output numbering.....                                        | 499  |
+| VII.4  Comments.....                                                       | 499  |
+| Appendix VIII – Ambient temperature and wind loading effects .....         | 500  |
+| VIII.1 Synchronization tolerances to plant delay variations .....          | 500  |
+| VIII.2 Change in propagation delay due to temperature changes .....        | 501  |
+| Bibliography.....                                                          | 503  |
+
+# Recommendation ITU-T J.122
+
+# Second-generation transmission systems for interactive cable television services – IP cable modems
+
+# 1 Scope and purpose
+
+## 1.1 Scope
+
+This Recommendation defines the second generation of radio-frequency interface specifications for high-speed data-over-cable systems.
+
+There are differences in the cable spectrum planning practices adopted for different networks in the world. Therefore, three options for physical layer technology are included, which have equal priority and are not required to be interoperable. One technology option is based on the downstream multi-programme television distribution that is deployed using 6 MHz channelling, and supports upstream transmission in the 5-42 MHz region. The second technology option is based on a multi-programme television distribution using 8 MHz channel spacing and supports upstream in the 5-65 MHz region. The third technology option is based on 6 MHz channel spacing and supports upstream in the 10-55 MHz region. All options have equal status. The first of these options is defined in clauses 4, 6 and 7, whereas the second and third are defined by replacing the content of those clauses with the content of Annex F or Annex J. Compliance with this Recommendation requires compliance with only one of these implementations. It is not required that equipment built to one option shall interoperate with equipment built to another.
+
+These optional physical-layer technologies allow operators some flexibility within any frequency planning, EMC and safety requirements that are mandated for their area of operation. For example, the 6 MHz downstream-based option defined by clauses 4, 6 and 7 might be deployable within an 8 MHz channel plan.
+
+Frequency planning, safety and EMC requirements are a national matter and are not covered by this Recommendation. Compliance remains the operators' responsibility.
+
+All optional physical-layer technologies are required to be backwards compatible with the earlier versions of those options defined in [DOCS9], [DOCS11] and [DOCS12].
+
+NOTE – The structure and content of this Recommendation have been organized for ease of use by those familiar with the original source material; as such, the usual style of ITU-T recommendations has not been applied.
+
+## 1.2 Requirements
+
+If this Recommendation is implemented, the key words "MUST" and "SHALL" as well as "REQUIRED" are to be interpreted as indicating a mandatory aspect of this Recommendation. The keywords indicating a certain level of significance of a particular requirement that are used throughout this Recommendation are summarized below.
+
+**MUST** This word or the adjective "REQUIRED" means that the item is an absolute requirement of this Recommendation.
+
+**MUST NOT** This phrase means that the item is an absolute prohibition of this Recommendation.
+
+**SHOULD** This word or the adjective "RECOMMENDED" means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications
+
+should be understood and the case carefully weighed before choosing a different course.
+
+**SHOULD NOT** This phrase means that there may exist valid reasons in particular circumstances when the listed behaviour is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behaviour described with this label.
+
+**MAY** This word or the adjective "OPTIONAL" means that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product, for example; another vendor may omit the same item.
+
+This Recommendation defines many features and parameters, and a valid range for each parameter is usually specified. Equipment (CM and CMTS) requirements are always explicitly stated. Equipment must comply with all mandatory (MUST and MUST NOT) requirements to be considered compliant with this Recommendation. Support of non-mandatory features and parameter values is optional.
+
+## 1.3 Background
+
+### 1.3.1 Service goals
+
+As cable operators have widely deployed high-speed data services on cable television systems, the demand for upstream bandwidth has increased, particularly with the popularity of more symmetric data applications. The current Recommendation has been created for the purpose of increasing channel capacity and improving noise immunity.
+
+The intended service will allow transparent bidirectional transfer of Internet protocol (IP) traffic, between the cable system headend and customer locations, over an all-coaxial or hybrid-fibre/coax (HFC) cable network. This is shown in simplified form in Figure 1-1.
+
+![Diagram of transparent IP traffic through the data-over-cable system](54fabc351eda5228d2fa28cd9ba07971_img.jpg)
+
+The diagram illustrates the flow of IP traffic through a data-over-cable system. On the left, a box labeled 'Wide area network' is connected via a double-headed arrow to a box labeled 'Cable modem termination system (CMTS)'. This connection is labeled 'CMTS network side interface'. From the CMTS, a single-headed arrow points right through a box labeled 'Cable network' to a box labeled 'Cable modem (CM)'. From the CM, a double-headed arrow points right to a box labeled 'Customer premises equipment' (represented by a computer icon). This connection is labeled 'CM customer premises equipment interface'. A bracket below the CMTS, Cable network, and CM is labeled 'Transparent IP traffic through the system'. The text 'J.122\_F1-1' is in the bottom right corner.
+
+Diagram of transparent IP traffic through the data-over-cable system
+
+**Figure 1-1 – Transparent IP traffic through the data-over-cable system**
+
+The transmission path over the cable system is realized at the headend by a cable modem termination system (CMTS), and at each customer location by a cable modem (CM). At the headend (or hub), the interface to the data-over-cable system is called the cable modem termination system-network side interface (CMTS-NSI). At the customer locations, the interface is called the cable-modem-to-customer-premises-equipment interface (CMCI). The intent is for operators to transparently transfer IP traffic between these interfaces, including but not limited to datagrams, DHCP, ICMP and IP group addressing (broadcast and multicast).
+
+### 1.3.2 Reference architecture
+
+The reference architecture for the data-over-cable services and interfaces is shown in Figure 1-2.
+
+![Figure 1-2 – Data-over-cable reference architecture. This block diagram shows the internal components of a Distribution hub or headend and its external connections. On the left, external connections include PSTN (via Copper pairs, DS1 or DS3), WAN, and Backbone network. The headend contains a Telco return access concentrator (TRAC), a Generic headend switch or backbone transport adapter, a Local server facility, and a Remote server facility. The central part is the Cable modem termination system (CMTS), which includes Network termination, Mod, Demod, and is connected to an Operations support system (via DOCS-OSSI), a Cable modem termination system – network side interface (CMTS-NSI), a Baseline privacy interface (BPI), and a Security & Access Controller. Downstream signals (Video 1, Video 2, Data) are combined and sent to a Tx (Transmitter). Upstream signals (Data) are received from a Rx (Receiver) and sent to an Upstream splitter and filter bank. The Tx and Rx are connected to a Distribution network via Fibre and Coax. The Fibre path goes through an O/E node to a Cable modem, which connects to Customer premises equipment via a Cable modem to CPE interface (CMCI). The Coax path goes through another O/E node to a Cable modem to RF interface (CMTRI), which connects to a Telco return line. The diagram is labeled J.122_F1-2.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg)
+
+Figure 1-2 – Data-over-cable reference architecture. This block diagram shows the internal components of a Distribution hub or headend and its external connections. On the left, external connections include PSTN (via Copper pairs, DS1 or DS3), WAN, and Backbone network. The headend contains a Telco return access concentrator (TRAC), a Generic headend switch or backbone transport adapter, a Local server facility, and a Remote server facility. The central part is the Cable modem termination system (CMTS), which includes Network termination, Mod, Demod, and is connected to an Operations support system (via DOCS-OSSI), a Cable modem termination system – network side interface (CMTS-NSI), a Baseline privacy interface (BPI), and a Security & Access Controller. Downstream signals (Video 1, Video 2, Data) are combined and sent to a Tx (Transmitter). Upstream signals (Data) are received from a Rx (Receiver) and sent to an Upstream splitter and filter bank. The Tx and Rx are connected to a Distribution network via Fibre and Coax. The Fibre path goes through an O/E node to a Cable modem, which connects to Customer premises equipment via a Cable modem to CPE interface (CMCI). The Coax path goes through another O/E node to a Cable modem to RF interface (CMTRI), which connects to a Telco return line. The diagram is labeled J.122\_F1-2.
+
+Figure 1-2 – Data-over-cable reference architecture
+
+### 1.3.3 Categories of interface specification
+
+The basic reference architecture of Figure 1-2 involves four interface categories.
+
+**Data interfaces** – These are the CMCI and CMTS-NSI, corresponding respectively to the cable-modem-to-customer-premises-equipment (CPE) interface (for example, between the customer's computer and the cable modem), and the cable modem termination system network side interface between the cable modem termination system and the data network.
+
+**Operations support systems interfaces** – These are network element management layer interfaces between the network elements and the high-level operations support systems (OSSs), which support the basic business processes.
+
+**RF interfaces** – The RF interfaces defined in this Recommendation are the following:
+
+- between the cable modem and the cable network;
+- between the CMTS and the cable network in the downstream direction (traffic toward the customer);
+- between the CMTS and the cable network in the upstream direction (traffic from the customer).
+
+**Security interfaces** – Baseline data-over-cable security is defined in [DOCS8].
+
+### 1.3.4 Statement of compatibility
+
+This Recommendation specifies an interface, commonly referred to as DOCS 2.0, which is the second generation of the interface specified in [DOCS9], [DOCS11] and [DOCS12], commonly referred to as DOCS 1.x. DOCS 2.0 must be backward- and forward-compatible with equipment built to the previous Recommendations. DOCS 2.0-compliant CMs MUST interoperate seamlessly with DOCS 1.x CMTSs, albeit in the 1.x mode, as the case may be. DOCS 2.0-compliant CMTSs MUST seamlessly support DOCS 1.x CMs.
+
+Refer to Annex G for further interoperability information.
+
+## 1.4 Conventions for this Recommendation
+
+In this Recommendation, the following convention applies any time a bit field is displayed in a figure. The bit field should be interpreted by reading the figure from left to right, then from top to bottom, with the MSB being the first bit so read and the LSB being the last bit so read.
+
+# 2 References
+
+## 2.1 Normative 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.
+
+[DOCS3] Data-Over-Cable Service Interface Specifications, *Cable Modem Termination System – Network Side Interface Specification*, SP-CMTS-NSI01-960702.
+
+[DOCS4] Data-Over-Cable Service Interface Specifications, *Cable Modem to Customer Premise Equipment Interface Specification*, SP-CMCI-I04-000714.
+
+- [DOCS5] ANSI/SCTE 79-2 2002, *Data-Over-Cable System S 2.0 s, Operations Support System Interface*.
+- [DOCS8] ITU-T J.112 Annex B (2001), *Data-over-cable service interface specifications, Annex O – Privacy for J.112 Annex B Implementations*.
+- [DOCS9] SCTE 22-1 2002, *Data-Over-Cable Service Interface Specification, DOCSIS 1.0 Radio Frequency Interface (RFI)*.
+- [DOCS11] ITU-T Recommendation J.112 Annex B (2001), *Data-over-cable service interface specifications: Radio-frequency interface specification*.
+- [DOCS12] ITU-T Recommendation J.112 Annex C (2002), *Data-over-cable service interface specifications: Radio-frequency interface specification using QAM technique*.
+- [IEEE 802] IEEE 802 (2001), *Local and Metropolitan Area Networks: Overview and Architecture*.
+- [IEC 60169-24] IEC 60169-24 (1991), *Radio-frequency connectors – Part 24: Radio-frequency coaxial connectors with screw coupling, typically for uses in 75 ohm cable distribution systems (Type F)*.
+- [ISO/IEC 8802-2] ISO/IEC 8802-2:1998 (ANSI/IEEE Std 802.2), *Information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Specific requirements – Part 2: Logical link control*.
+- [ISO/IEC 8802-3] ISO/IEC 8802-3:2000 (IEEE Std 802.3), *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*.
+- [ISO/IEC 15802-3] ISO/IEC 15802-3:1998 (ANSI/IEEE Std 802.1D), *Information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Common specifications – Part 3: Media Access Control (MAC) Bridges*.
+- [ISO/IEC 15802-1] ISO/IEC 15802-1:1995, *Information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Common specifications – Part 1: Medium Access Control (MAC) service definition*.
+- [ISO/IEC 10039] ISO/IEC 10039:1991, *Information technology – Open systems interconnection – Medium Access Control (MAC) service definition*.
+- [ITU-T H.222.0] ITU-T Recommendation H.222.0 (2000) | ISO/IEC 13818-1:2000, *Information technology – Generic coding of moving pictures and associated audio information: Systems*.
+- [ITU-T J.83] ITU-T Recommendation J.83 (2007), *Digital multi-programme systems for television, sound and data services for cable distribution*.
+- [ITU-T J.162] ITU-T Recommendation J.162 (2007), *Network call signalling protocol for the delivery of time-critical services over cable television networks using cable modems*.
+- [ITU-T J.163] ITU-T Recommendation J.163 (2007), *Dynamic quality of service for the provision of real-time services over cable television networks using cable modems*.
+
+- [ITU-T X.25] ITU-T Recommendation X.25 (1996), *Interface between Data Terminal Equipment (DTE) and Data Circuit-terminating Equipment (DCE) for terminals operating in the packet mode and connected to public data networks by dedicated circuit.*
+- [ITU-T X.690] ITU-T X.690-series (2002) | ISO/IEC 8825:2002, *Information technology – ASN.1 encoding rules.*
+- [ITU-T Z.100] ITU-T Recommendation Z.100 (2002), *Specification and Description Language (SDL).*
+- [L2VPN] DOCSIS Business Services over DOCSIS, *Layer 2 Virtual Private Networks*, CM-SP-L2VPN-105-070803, August 3, 2007, Cable Television Laboratories, Inc.
+- [RFC 791] IETF RFC 791 (1981), *Internet Protocol.*
+- [RFC 826] IETF RFC 826 (1982), *Ethernet Address Resolution Protocol: Or converting network protocol addresses to 48.bit Ethernet address for transmission on Ethernet Hardware.*
+- [RFC 868] IETF RFC 868 (1983), *Time Protocol.*
+- [RFC 1042] IETF RFC 1042 (1988), *Standard for the transmission of IP datagrams over IEEE 802 networks.*
+- [RFC 1123] IETF RFC 1123 (1989), *Requirements for Internet Hosts – Application and Support.*
+- [RFC 1157] IETF RFC 1157 (1990), *Simple Network Management Protocol (SNMP).*
+- [RFC 1350] IETF RFC 1350 (1992), *The TFTP Protocol (Revision 2).*
+- [RFC 2104] IETF RFC 2104 (1997), *HMAC: Keyed-Hashing for Message Authentication.*
+- [RFC 2131] IETF RFC 2131 (1997), *Dynamic Host Configuration Protocol.*
+- [RFC 2132] IETF RFC 2132 (1997), *DHCP Options and BOOTP Vendor Extensions.*
+- [RFC 2236] IETF RFC 2236 (1997), *Internet Group Management Protocol, Version 2.*
+- [RFC 2349] IETF RFC 2349 (1998), *TFTP Timeout Interval and Transfer Size Options.*
+- [RFC 2786] IETF RFC 2786 (2000), *Diffie-Helman USM Key Management Information Base and Textual Convention.*
+- [RFC 3046] IETF RFC 3046 (2001), *DHCP Relay Agent Information Option.*
+- [FIPS 180-1] FIPS 180-1 (1995): *Secure Hash Standard.*
+
+## 2.2 Informative references
+
+- [b-CableLabs2] CableLabs2 (1999), *Digital Transmission Characterization of Cable Television Systems.*
+- [b-EIA 542] CEA Standard 542-B (2003), *Cable Television Channel Identification Plan.*
+- [b-EN 300 429] ETSI EN 300 429 V1.2.1 (1998), *Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for cable systems.*
+- [b-ID-IGMP] FENNER (W.): IGMP-based Multicast Forwarding ("IGMP Proxying"), IETF Internet Draft, 2000.  
+<http://www.ietf.org/proceedings/00dec/I-D/draft-fenner-igmp-proxy-03.txt>
+- [b-IEEE 802.1Q] IEEE 802.1Q (2003), *Virtual Bridged Local Area Networks.*
+
+- [b-IMA] Internet Multicast Addresses, *Internet Assigned Numbers Authority*.  
+<http://www.iana.org/assignments/multicast-addresses>.
+- [b-NCTA] NCTA Recommended Practices for Measurements on Cable Television Systems, *National Cable Television Association*, 2nd Edition, Washington DC, 1993.
+- [b-RFC 1058] IETF RFC 1058 (1988), *Routing Information Protocol*.
+- [b-RFC 1493] IETF RFC 1493 (1993), *Definitions of Managed Objects for Bridges*.
+- [b-RFC 1633] IETF RFC 1633 (1994), *Integrated Services in the Internet Architecture: an Overview*.
+- [b-RFC 1812] IETF RFC 1812 (1995), *Requirements for IP Version 4 Routers*.
+- [b-RFC 2212] IETF RFC 2212 (1997), *Specification of Guaranteed Quality of Service*.
+- [b-RFC 2669] IETF RFC 2669 (1999), *DOCSIS Cable Device MIB Cable Device Management Information Base for DOCSIS compliant Cable Modems and Cable Modem Termination Systems*.
+- [b-VECCHI] VECCHI (M.), FAHIM (M.): Architectural Model: The Spectrum Management Application (SMA) and the Common Spectrum Management Interface (CSMI), *Time Warner Cable*, Englewood, CO, 1995.
+
+# 3 Glossary
+
+## 3.1 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|            |                                                         |
+|------------|---------------------------------------------------------|
+| ARP        | Address Resolution Protocol                             |
+| ATM        | Asynchronous Transfer Mode                              |
+| BPDU       | Bridge Protocol Data Unit                               |
+| C/N or CNR | Carrier-to-Noise Ratio                                  |
+| CCCM       | CPE Controlled Cable Modem                              |
+| CM         | Cable Modem                                             |
+| CMCI       | Cable Modem to CPE Interface                            |
+| CMTS       | Cable Modem Termination System                          |
+| CMTS-NSI   | Cable Modem Termination System – Network Side Interface |
+| CPE        | Customer Premises Equipment                             |
+| CSO        | Composite Second Order beat                             |
+| CTB        | Composite Triple Beat                                   |
+| DCC        | Dynamic Channel Change                                  |
+| DHCP       | Dynamic Host Configuration Protocol                     |
+| DOCS       | Data-Over-Cable System                                  |
+| FDDI       | Fibre Distributed Data Interface                        |
+| HF         | High Frequency                                          |
+| HFC        | Hybrid Fibre/Coax system                                |
+| HRC        | Harmonic Related Carrier                                |
+
+|      |                                       |
+|------|---------------------------------------|
+| ICMP | Internet Control Message Protocol     |
+| IE   | Information Element                   |
+| IGMP | Internet Group Management Protocol    |
+| IP   | Internet Protocol                     |
+| IRC  | Incremental Related Carriers          |
+| IUC  | Interval Usage Code                   |
+| LAN  | Local Area Network                    |
+| LLC  | Logical Link Control procedure        |
+| MAC  | Media Access Control procedure        |
+| MAP  | Bandwidth Allocation Map              |
+| MPEG | Moving Picture Experts Group          |
+| MSAP | MAC Service Access Point              |
+| MTTR | Mean Time to Repair                   |
+| NTSC | National Television Systems Committee |
+| OSI  | Open Systems Interconnection          |
+| OUI  | Organizationally Unique Identifier    |
+| PHS  | Payload Header Suppression            |
+| PHY  | Physical layer                        |
+| PID  | Packet Identifier                     |
+| PMD  | Physical Media Dependent              |
+| PSI  | Program-Specific Information          |
+| PUSI | Payload Unit Start Indicator          |
+| QAM  | Quadrature Amplitude Modulation       |
+| QPSK | Quadrature Phase-Shift Keying         |
+| RF   | Radio Frequency                       |
+| RFC  | Request for Comments                  |
+| RIP  | Routing Information Protocol          |
+| SAID | Security Association Identifier       |
+| SAP  | Service Access Point                  |
+| SDU  | Service Data Unit                     |
+| SFID | Service Flow Identifier               |
+| SID  | Service Identifier                    |
+| SMS  | Spectrum Management System            |
+| SNAP | SubNetwork Access Protocol            |
+| SNMP | Simple Network Management Protocol    |
+| TCP  | Transmission Control Protocol         |
+| TFTP | Trivial File-Transfer Protocol        |
+
+|     |                             |
+|-----|-----------------------------|
+| TLV | Type/Length/Value           |
+| ToS | Type of Service             |
+| UCC | Upstream Channel Change     |
+| UCD | Upstream Channel Descriptor |
+
+## 3.2 Terms and definitions
+
+This Recommendation defines the following terms:
+
+**3.2.1 active service flow:** An admitted service flow from the CM to the CMTS which is available for packet transmission.
+
+**3.2.2 address resolution protocol (ARP):** A protocol of the IETF for converting network addresses to 48-bit Ethernet addresses.
+
+**3.2.3 admitted service flow:** A service flow, either provisioned or dynamically signalled, which is authorized and for which resources have been reserved but is not active.
+
+**3.2.4 allocation:** A group of contiguous mini-slots in a MAP which constitute a single transmit opportunity.
+
+**3.2.5 American National Standards Institute (ANSI):** A US standards body.
+
+**3.2.6 asynchronous transfer mode (ATM):** A protocol for the transmission of a variety of digital signals using uniform 53-byte cells.
+
+**3.2.7 A-TDMA:** DOCS 2.0 TDMA mode (as distinguished from DOCS 1.x TDMA).
+
+**3.2.8 authorization module:** The authorization module is an abstract module that the CMTS can contact to authorize service flows and classifiers. The authorization module tells the CMTS whether the requesting CM is authorized for the resources it is requesting.
+
+**3.2.9 availability:** In cable television systems, availability is the long-term ratio of the actual RF channel operation time to scheduled RF channel operation time (expressed as a percent value) and is based on a bit error rate (BER) assumption.
+
+**3.2.10 bandwidth allocation map:** The MAC management message that the CMTS uses to allocate transmission opportunities to CMs.
+
+**3.2.11 bridge protocol data unit (BPDU):** Spanning tree protocol messages as defined in [ISO/IEC 15802-3].
+
+**3.2.12 broadcast addresses:** A predefined destination address that denotes the set of all data network service access points.
+
+**3.2.13 burst:** A single continuous RF signal from the upstream transmitter, from transmitter on to transmitter off.
+
+**3.2.14 burst error second:** Any errored second containing at least 100 errors.
+
+**3.2.15 cable modem (CM):** A modulator-demodulator at subscriber locations intended for use in conveying data communications on a cable television system.
+
+**3.2.16 cable modem termination system (CMTS):** Cable modem termination system, located at the cable television system headend or distribution hub, which provides complementary functionality to the cable modems to enable data connectivity to a wide-area network.
+
+**3.2.17 cable modem termination system – network side interface (CMTS-NSI):** The interface, defined in [DOCS3], between a CMTS and the equipment on its network side.
+
+**3.2.18 cable modem to CPE interface (CMCI):** The interface, defined in [DOCS4], between a CM and CPE.
+
+**3.2.19 carrier hum modulation:** The peak-to-peak magnitude of the amplitude distortion relative to the RF carrier signal level due to the fundamental and low-order harmonics of the power-supply frequency.
+
+**3.2.20 carrier-to-noise ratio (C/N or CNR):** The ratio of signal power to noise power in the defined measurement bandwidth. For digital modulation,  $CNR = E_s/N_0$ , the energy-per-symbol to noise-density ratio; the signal power is measured in the occupied bandwidth, and the noise power is normalized to the modulation-rate bandwidth. For video, the measurement bandwidth is 4 MHz.
+
+**3.2.21 CPE controlled cable modem (CCCM):** Refer to the DOCS cable modem to customer premises equipment interface (CMCI) specification.
+
+**3.2.22 channel:** The frequency spectrum occupied by a signal. Usually specified by centre frequency and bandwidth parameters.
+
+**3.2.23 chip:** Each of the 128 bits comprising the S-CDMA spreading codes.
+
+**3.2.24 chip duration:** The time to transmit one chip of the S-CDMA spreading code. The inverse of the chip rate.
+
+**3.2.25 chip rate:** The rate at which individual chips of the S-CDMA spreading codes are transmitted (1280 to 5120 kHz).
+
+**3.2.26 classifier:** A set of criteria used for packet matching according to TCP, UDP, IP, LLC, and/or 802.1P/Q packet fields. A classifier maps each packet to a service flow. A downstream classifier is used by the CMTS to assign packets to downstream service flows. An upstream classifier is used by the CM to assign packets to upstream service flows.
+
+**3.2.27 code-hopping matrix:** A shifted version of the reference code matrix (see below) that is used when code hopping is employed to vary the codes used by each CM. The code-hopping matrix is either 128 rows by 128 columns (when all 128 codes are active) or is 127 rows by 128 columns (when less than 128 codes are active in the S-CDMA spreader-on frame). When less than 128 codes are active, code 0 (all ones) is deleted from the matrix, but all remaining codes are still cycled through even if less than 127 codes are active in a frame.
+
+**3.2.28 composite second order beat (CSO):** The peak of the average level of distortion products due to second-order non-linearities in cable system equipment.
+
+**3.2.29 composite triple beat (CTB):** The peak of the average level of distortion components due to third-order non-linearities in cable system equipment.
+
+**3.2.30 cross-modulation:** A form of television signal distortion where modulation from one or more television channels is imposed on another channel or channels.
+
+**3.2.31 customer:** See end user.
+
+**3.2.32 customer premises equipment (CPE):** Equipment at the end user's premises; MAY be provided by the end user or the service provider.
+
+**3.2.33 data link layer:** Layer 2 in the open system interconnection (OSI) architecture; the layer that provides services to transfer data over the transmission link between open systems.
+
+**3.2.34 distribution hub:** A location in a cable television network which performs the functions of a headend for customers in its immediate area, and which receives some or all of its television programme material from a master headend in the same metropolitan or regional area.
+
+**3.2.35 DOCS 1.0:** Data-over-cable system defined by [DOCS9].
+
+**3.2.36 DOCS 1.1:** Data-over cable system defined by [DOCS11].
+
+**3.2.37 DOCS 1.x:** Abbreviation for "DOCS 1.0 or 1.1".
+
+**3.2.38 DOCS 2.0:** Data-over-cable system as defined in this Recommendation.
+
+- 3.2.39 downstream:** In cable television, the direction of transmission from the headend to the subscriber.
+- 3.2.40 drop cable:** Coaxial cable that connects to a residence or service location from a directional coupler (tap) on the nearest coaxial feeder cable.
+- 3.2.41 dynamic host configuration protocol (DHCP):** An Internet protocol used for assigning network-layer (IP) addresses.
+- 3.2.42 dynamic range:** The ratio between the greatest signal power that can be transmitted over a multichannel analogue transmission system without exceeding distortion or other performance limits, and the least signal power that can be utilized without exceeding noise, error rate or other performance limits.
+- 3.2.43 Electronic Industries Association (EIA):** A voluntary body of manufacturers which, among other activities, prepares and publishes standards.
+- 3.2.44 end user:** A human being, organization or telecommunication system that accesses the network in order to communicate via the services provided by the network.
+- 3.2.45 errored second:** Any one-second interval containing at least one bit error.
+- 3.2.46 extended subsplit:** A frequency division scheme that allows bidirectional traffic on a single coaxial cable. Reverse path signals come to the headend from 5 to 42 MHz. Forward path signals go from the headend from 50 or 54 MHz to the upper frequency limit.
+- 3.2.47 feeder cable:** Coaxial cables that run along streets within the served area and connect between the individual taps which serve the customer drops.
+- 3.2.48 fibre distributed data interface (FDDI):** A fibre-based LAN standard.
+- 3.2.49 fibre node:** A point of interface between a fibre trunk and the coaxial distribution.
+- 3.2.50 forward channel:** The direction of RF signal flow away from the headend toward the end user; equivalent to downstream.
+- 3.2.51 frame:** See MAC frame, S-CDMA frame and MPEG frame.
+- 3.2.52 group delay:** The difference in transmission time between the highest and lowest of several frequencies through a device, circuit or system.
+- 3.2.53 guard time:** Minimum time allocated between bursts in the upstream referenced from the symbol centre of the last symbol of a burst to the symbol centre of the first symbol of the following burst. The guard time should be at least the duration of five symbols plus the maximum system timing error.
+- 3.2.54 harmonic related carrier (HRC):** A method of spacing television channels on a cable television system in exact 6-MHz increments, with all carrier frequencies harmonically related to a common reference.
+- 3.2.55 headend:** The central location on the cable network that is responsible for injecting broadcast video and other signals in the downstream direction. See also master headend, distribution hub.
+- 3.2.56 header:** Protocol control information located at the beginning of a protocol data unit.
+- 3.2.57 high frequency (HF):** Used in this Recommendation to refer to the entire subsplit (5-30 MHz) and extended subsplit (5-42 MHz) band used in reverse channel communications over the cable television network.
+- 3.2.58 high return:** A frequency division scheme that allows bidirectional traffic on a single coaxial cable. Reverse channel signals propagate to the headend above the downstream passband.
+
+- 3.2.59 hum modulation:** Undesired modulation of the television visual carrier by the fundamental or low-order harmonics of the power supply frequency, or other low-frequency disturbances.
+- 3.2.60 hybrid fibre/coax (HFC) system:** A broadband bidirectional shared-media transmission system using fibre trunks between the headend and the fibre nodes, and coaxial distribution from the fibre nodes to the customer locations.
+- 3.2.61 incremental related carriers (IRC):** A method of spacing NTSC television channels on a cable television system in which all channels except 5 and 6 correspond to the standard channel plan, used to reduce composite triple beat distortions.
+- 3.2.62 Institute of Electrical and Electronic Engineers (IEEE):** A voluntary organization which, among other things, sponsors standards committees and is accredited by the American National Standards Institute.
+- 3.2.63 International Electrotechnical Commission (IEC):** An international standards body.
+- 3.2.64 International Organization for Standardization (ISO):** An international standards body, commonly known as the International Standards Organization.
+- 3.2.65 Internet control message protocol (ICMP):** An Internet network-layer protocol.
+- 3.2.66 Internet Engineering Task Force (IETF):** A body responsible, among other things, for developing standards used in the Internet.
+- 3.2.67 Internet group management protocol (IGMP):** A network-layer protocol for managing multicast groups on the Internet.
+- 3.2.68 impulse noise:** Noise characterized by non-overlapping transient disturbances.
+- 3.2.69 information element:** The fields that make up a MAP and define individual grants, deferred grants, etc.
+- 3.2.70 Internet protocol (IP):** An Internet network-layer protocol.
+- 3.2.71 interval usage code (IUC):** A field in MAPs and UCDs to link burst profiles to grants.
+- 3.2.72 latency:** The time, expressed in quantity of symbols, taken for a signal element to pass through a device.
+- 3.2.73 layer:** A subdivision of the open system interconnection (OSI) architecture, constituted by subsystems of the same rank
+- 3.2.74 link layer:** See data link layer.
+- 3.2.75 local area network (LAN):** A non-public data network in which serial transmission is used for direct data communication among data stations located on the user's premises.
+- 3.2.76 logical link control (LLC) procedure:** In a local area network (LAN) or a metropolitan area network (MAN), that part of the protocol that governs the assembling of data link layer frames and their exchange between data stations, independent of how the transmission medium is shared.
+- 3.2.77 logical (upstream) channel:** A MAC entity identified by a unique channel ID and for which bandwidth is allocated by an associated MAP message. A physical upstream channel may support multiple logical upstream channels. The associated UCD and MAP messages completely describe the logical channel.
+- 3.2.78 MAC frame:** MAC header plus optional PDU.
+- 3.2.79 MAC service access point (MSAP):** An attachment to a MAC-sublayer domain. Refer to clauses 5.2 and 8.1.2.2.
+- 3.2.80 master headend:** A headend which collects television programme material from various sources by satellite, microwave, fibre and other means, and distributes this material to distribution
+
+hubs in the same metropolitan or regional area. A master headend MAY also perform the functions of a distribution hub for customers in its own immediate area.
+
+**3.2.81 mean time to repair (MTTR):** In cable television systems, the MTTR is the average elapsed time from the moment a loss of RF channel operation is detected up to the moment the RF channel operation is fully restored.
+
+**3.2.82 media access control (MAC) address:** The "built-in" hardware address of a device connected to a shared medium.
+
+**3.2.83 media access control (MAC) procedure:** In a subnetwork, that part of the protocol that governs access to the transmission medium independent of the physical characteristics of the medium, but taking into account the topological aspects of the subnetworks, in order to enable the exchange of data between nodes. MAC procedures include framing, error protection and acquiring the right to use the underlying transmission medium.
+
+**3.2.84 media access control (MAC) sublayer:** The part of the data link layer that supports topology-dependent functions and uses the services of the physical layer to provide services to the logical link control (LLC) sublayer.
+
+**3.2.85 micro-reflections:** Echoes in the forward transmission path due to departures from ideal amplitude and phase characteristics.
+
+**3.2.86 mid split:** A frequency division scheme that allows bidirectional traffic on a single coaxial cable. Reverse channel signals propagate to the headend from 5 to 108 MHz. Forward path signals go from the headend from 162 MHz to the upper frequency limit. The diplex crossover band is located from 108 to 162 MHz.
+
+**3.2.87 mini-slot:** A "mini-slot" is an integer multiple of 6.25-microsecond increments. The relationship between mini-slots, bytes and time ticks is described in clause 9.3.4.
+
+**3.2.88 modulation rate:** The signalling rate of the upstream modulator (1280 to 5120 kHz). In S-CDMA, the chip rate. In TDMA, the channel symbol rate.
+
+**3.2.89 Moving Picture Experts Group (MPEG):** A voluntary body which develops standards for digital compressed moving pictures and associated audio.
+
+**3.2.90 multipoint access:** User access in which more than one terminal equipment is supported by a single network termination.
+
+**3.2.91 multipoint connection:** A connection among more than two data network terminations.
+
+**3.2.92 National Cable Television Association (NCTA):** A voluntary association of cable television operators which, among other things, provides guidance on measurements and objectives for cable television systems in the United States.
+
+**3.2.93 National Television Systems Committee (NTSC):** Committee which defined the analogue colour television broadcast standard used today in North America.
+
+**3.2.94 network layer:** Layer 3 in the open systems interconnection (OSI) architecture; the layer that provides services to establish a path between open systems.
+
+**3.2.95 network management:** The functions related to the management of data link layer and physical layer resources and their stations across the data network supported by the hybrid fibre/coax system.
+
+**3.2.96 number of allocated codes:** The total number of codes which a single CM uses in a single S-CDMA frame. This number is determined by the size of the grants in mini-slots and the mapping of these mini-slots to S-CDMA frames (note that a CM may receive multiple grants which are mapped to a single S-CDMA frame). The number of allocated codes can be in the range of the
+
+number of codes per mini-slot to the number of active codes, and may vary from frame to frame, but is constant within an S-CDMA frame.
+
+**3.2.97 open systems interconnection (OSI):** A framework of ISO standards for communication between different systems made by different vendors, in which the communication process is organized into seven different categories that are placed in a layered sequence based on their relationship to the user. Each layer uses the layer immediately below it and provides a service to the layer above. Layers 7 through 4 deal with end-to-end communication between the message source and destination, and layers 3 through 1 deal with network functions.
+
+**3.2.98 organizationally unique identifier (OUI):** A 3-octet IEEE-assigned identifier that can be used to generate universal LAN MAC addresses and protocol identifiers per ANSI/IEEE Std 802 for use in local and metropolitan area network applications.
+
+**3.2.99 packet identifier (PID):** A unique integer value used to identify elementary streams of a programme in a single- or multi-programme MPEG-2 stream.
+
+**3.2.100 partial grant:** A grant that is smaller than the corresponding bandwidth request from the CM.
+
+**3.2.101 payload header suppression (PHS):** The suppression of the header in a payload packet (e.g., the suppression of the Ethernet header in forwarded packets).
+
+**3.2.102 payload unit start indicator (PUSI):** A flag in an MPEG header. A value of 1 indicates the presence of a pointer field as the first byte of the payload.
+
+**3.2.103 physical layer (PHY):** Layer 1 in the Open System Interconnection (OSI) architecture; the layer that provides services to transmit bits or groups of bits over a transmission link between open systems and which entails electrical, mechanical and handshaking procedures.
+
+**3.2.104 physical media dependent (PMD) sublayer:** A sublayer of the physical layer which is concerned with transmitting bits or groups of bits over particular types of transmission link between open systems and which entails electrical, mechanical and handshaking procedures.
+
+**3.2.105 primary service flow:** All CMs have a primary upstream service flow and a primary downstream service flow. They ensure that the CM is always manageable and they provide a default path for forwarded packets that are not classified to any other service flow.
+
+**3.2.106 programme-specific information (PSI):** In MPEG-2, normative data necessary for the demultiplexing of transport streams and the successful regeneration of programmes.
+
+**3.2.107 programme stream:** In MPEG-2, a multiplex of variable-length digital video and audio packets from one or more programme sources having a common time-base.
+
+**3.2.108 protocol:** A set of rules and formats that determines the communication behaviour of layer entities in the performance of the layer functions.
+
+**3.2.109 provisioned service flow:** A service flow that has been provisioned as part of the registration process, but has not yet been activated or admitted. It may still require an authorization exchange with a policy module or external policy server prior to admission.
+
+**3.2.110 QoS parameter set:** The set of service flow encodings that describe the quality of service attributes of a service flow or a service class (refer to clause C.2.2.5).
+
+**3.2.111 quadrature amplitude modulation (QAM):** A method of modulating digital signals onto a radio-frequency carrier signal involving both amplitude and phase coding.
+
+**3.2.112 quadrature phase-shift keying (QPSK):** A method of modulating digital signals onto a radio-frequency carrier signal using four phase states to code two digital bits.
+
+**3.2.113 radio frequency (RF):** In cable television systems, this refers to electromagnetic signals in the range 5 to 1000 MHz.
+
+**3.2.114 reference code matrix:** A 128-by-128 element matrix formed by stacking successive spreading codes on top of each other, i.e., the bottom row of the reference code matrix is code 0 (all ones) and the top row is code 127. The code elements are placed in the matrix from right to left, i.e., the right-most column of the code matrix is the first element of each code, and the left-most column is the last element of each code.
+
+**3.2.115 request for comments (RFC):** A technical policy document of the IETF; these documents can be accessed on the worldwide web at <http://www.rfc-editor.org/>.
+
+**3.2.116 return loss:** The parameter describing the attenuation of a guided wave signal (e.g., via a coaxial cable) returned to a source by a device or medium resulting from reflections of the signal generated by the source.
+
+**3.2.117 reverse channel:** The direction of signal flow towards the headend, away from the subscriber; equivalent to upstream.
+
+**3.2.118 routing information protocol (RIP):** A protocol of the IETF for exchanging routing information about IP networks and subnets.
+
+**3.2.119 S-CDMA frame:** A two dimensional representation of mini-slots, where the dimensions are codes and time. An S-CDMA frame is composed of  $p$  active codes in the code dimension and  $K$  spreading intervals in the time dimension. Within the S-CDMA frame, the number of mini-slots is determined by the number of codes per mini-slot ( $c$ ) and  $p$ , the number of active codes in the S-CDMA frame. Each S-CDMA frame thus contains  $s$  mini-slots, where  $s = p/c$ , and each mini-slot contains  $c \times K$  information (QAM) symbols.
+
+**3.2.120 S-CDMA subframe:** A subframe is a vertically-smaller subset of an S-CDMA frame over which interleaving is performed, where the vertical dimension is  $R'$  codes, where  $R' \leq p$  (the number of active codes). A subframe is generally used to constrain the interleaving region to be of a similar size to the Reed-Solomon codeword in order to provide protection from impulse noise.
+
+**3.2.121 security association identifier (SAID):** A baseline privacy security identifier between a CMTS and a CM.
+
+**3.2.122 service access point (SAP):** The point at which services are provided by one layer, or sublayer to the layer immediately above it.
+
+**3.2.123 service class:** A set of queueing and scheduling attributes that is named and that is configured at the CMTS. A service class is identified by a service class name. A service class has an associated QoS parameter set.
+
+**3.2.124 service class name:** An ASCII string by which a service class may be referenced in modem configuration files and protocol exchanges.
+
+**3.2.125 service data unit (SDU):** Information that is delivered as a unit between peer service access points.
+
+**3.2.126 service flow:** A MAC-layer transport service which:
+
+- provides unidirectional transport of packets from the upper layer service entity to the RF;
+- shapes, polices and prioritizes traffic according to QoS traffic parameters defined for the flow.
+
+**3.2.127 service flow identifier (SFID):** An identifier assigned to a service flow by the CMTS (32 bits).
+
+**3.2.128 service flow reference:** A message parameter in configuration files and dynamic service MAC messages used to associate classifiers and other objects in the message with the service flow encodings of a requested service flow.
+
+- 3.2.129 service identifier (SID):** An identifier assigned by the CMTS (in addition to a service flow identifier) to an active or admitted upstream service flow (14 bits).
+- 3.2.130 simple network management protocol (SNMP):** A network management protocol of the IETF.
+- 3.2.131 spectrum management system (SMS):** A system, defined in [b-VECCHI], for managing the RF cable spectrum.
+- 3.2.132 spread symbol or spreading interval:** At the output of the spreader, a group of 128 chips which comprise a single S-CDMA spreading code, and are the result of spreading a single information (QAM) symbol. One spread symbol = one spreading interval = 128 chips = one information (QAM) symbol.
+- 3.2.133 spreader-off S-CDMA burst:** A transmission from a single CM in a spreader-off frame on an S-CDMA channel defined by the time in which the CM's transmitter turns on to the time it turns off. There will generally be several spreader-off bursts in a spreader-off frame.
+- 3.2.134 spreader-off S-CDMA frame:** TDMA mini-slots on an S-CDMA channel in which the spreader is turned off. These are differentiated from TDMA bursts on a TDMA channel in that, for example, the number of mini-slots per spreader-off S-CDMA burst frame is constrained to be the same as the number of mini-slots in a spreader-on S-CDMA frame(s). This number of mini-slots will be less than the number of TDMA mini-slots in a TDMA channel over the same time interval if the number of active codes is significantly less than 128.
+- 3.2.135 spreading interval:** Time to transmit a single complete S-CDMA spreading code, equal to the time to transmit 128 chips. Also, time to transmit a single information (QAM) symbol on an S-CDMA channel. See also spread symbol.
+- 3.2.136 sub-channel:** A logical channel sharing the same upstream spectrum (RF centre frequency and RF channel) with other logical channels.
+- 3.2.137 sublayer:** A subdivision of a layer in the open system interconnection (OSI) reference model.
+- 3.2.138 subnetwork:** Subnetworks are physically formed by connecting adjacent nodes with transmission links.
+- 3.2.139 subnetwork access protocol (SNAP):** An extension of the LLC header to accommodate the use of 802-type networks as IP networks.
+- 3.2.140 subscriber:** See "end user".
+- 3.2.141 subsplit:** A frequency-division scheme that allows bidirectional traffic on a single cable. Reverse path signals come to the headend from 5 to 30 MHz (up to 42 MHz on extended subsplit systems). Forward path signals go from the headend from 50 or 54 MHz to the upper frequency limit of the cable network.
+- 3.2.142 subsystem:** An element in a hierarchical division of an open system that interacts directly with elements in the next higher division or the next lower division of that open system.
+- 3.2.143 system clock period:** The period of the 10.24 MHz system clock, nominally 97.65625 ns.
+- 3.2.144 systems management:** Functions in the application layer related to the management of various open systems interconnection (OSI) resources and their status across all layers of the OSI architecture.
+- 3.2.145 tick:** 6.25-microsecond time intervals that are the reference for upstream mini-slot definition and upstream transmission times.
+- 3.2.146 tilt:** Maximum difference in transmission gain of a cable television system over a given bandwidth (typically the entire forward operating frequency range).
+
+**3.2.147 transit delay:** The time difference between the instant at which the first bit of a PDU crosses one designated boundary, and the instant at which the last bit of the same PDU crosses a second designated boundary.
+
+**3.2.148 transmission control protocol (TCP):** A transport-layer Internet protocol which ensures successful end-to-end delivery of data packets without error.
+
+**3.2.149 transmission convergence sublayer:** A sublayer of the physical layer that provides an interface between the data link layer and the PMD sublayer.
+
+**3.2.150 transmission link:** The physical unit of a subnetwork that provides the transmission connection between adjacent nodes.
+
+**3.2.151 transmission medium:** The material on which information signals may be carried; e.g., optical fibre, coaxial cable and twisted-wire pairs.
+
+**3.2.152 transmission system:** The interface and transmission medium through which peer physical layer entities transfer bits.
+
+**3.2.153 transmit on/off ratio:** In multiple-access systems, the ratio between the signal powers sent to line when transmitting and when not transmitting.
+
+**3.2.154 transport stream:** In MPEG-2, a packet-based method of multiplexing one or more digital video and audio streams having one or more independent time base(s) into a single stream.
+
+**3.2.155 trivial file-transfer protocol (TFTP):** An Internet protocol for transferring files without the requirement for user names and passwords that is typically used for automatic downloads of data and software.
+
+**3.2.156 trunk cable:** Cables that carry the signal from the headend to groups of subscribers. The cables can be either coaxial or fibre depending on the design of the system.
+
+**3.2.157 type/length/value (TLV):** An encoding of three fields in which the first field indicates the type of element, the second the length of the element, and the third field the value.
+
+**3.2.158 upstream:** The direction from the subscriber location toward the headend.
+
+**3.2.159 upstream channel descriptor (UCD):** The MAC management message used to communicate the characteristics of the upstream physical layer to the cable modems.
+
+# 4 Functional assumptions
+
+This clause describes the characteristics of cable television plant to be assumed for the purpose of operating a data-over-cable system. It is not a description of CMTS or CM parameters. The data-over-cable system MUST be interoperable within the environment described in this clause.
+
+This clause applies to the first technology option referred to in clause 1.1. For the second and third options, refer to Annexes F and J, respectively.
+
+Whenever any reference in this clause to frequency plans or compatibility with other services conflicts with any legal requirement for the area of operation, the latter shall take precedence. Any reference to NTSC analogue signals in 6-MHz channels does not imply that such signals are physically present.
+
+## 4.1 Broadband access network
+
+A coaxial-based broadband access network is assumed. This may take the form of either an all-coax or hybrid fibre/coax (HFC) network. The generic term "cable network" is used here to cover all cases.
+
+A cable network uses a shared-medium, tree-and-branch architecture with analogue transmission. The key functional characteristics assumed in this Recommendation are the following:
+
+- two-way transmission;
+- a maximum optical/electrical spacing between the CMTS and the most distant CM of 100 miles, although typical maximum separation may be 10-15 miles;
+- a maximum differential optical/electrical spacing between the CMTS and the closest and most distant modems of 100 miles, although this would typically be limited to 15 miles.
+
+## 4.2 Equipment assumptions
+
+### 4.2.1 Frequency plan
+
+In the downstream direction, the cable system is assumed to have a passband with a lower edge between 50 and 54 MHz and an upper edge that is implementation-dependent but is typically in the range of 300 to 864 MHz. Within that passband, NTSC analogue television signals in 6-MHz channels are assumed to be present on the standard, HRC or IRC frequency plans of [b-EIA 542], as well as other narrow-band and wideband digital signals.
+
+In the upstream direction, the cable system may have a subsplit (5-30 MHz) or extended subsplit (5-40 or 5-42 MHz) passband. NTSC analogue television signals in 6-MHz channels may be present, as well as other signals.
+
+### 4.2.2 Compatibility with other services
+
+The CM and CMTS MUST coexist with the other services on the cable network. In particular:
+
+- a) they MUST be interoperable in the cable spectrum assigned for CMTS-CM interoperation while the balance of the cable spectrum is occupied by any combination of television and other signals; and
+- b) they MUST NOT cause harmful interference to any other services that are assigned to the cable network in spectrum outside of that allocated to the CMTS.
+
+The latter is understood as:
+
+- no measurable degradation (highest level of compatibility);
+- no degradation below the perceptible level of impairments for all services (standard or medium level of compatibility); or
+- no degradation below the minimal standards accepted by the industry or other service provider (minimal level of compatibility).
+
+### 4.2.3 Fault isolation impact on other users
+
+As the data-over-cable system is a shared-media, point-to-multipoint system, fault-isolation procedures should take into account the potential harmful impact of faults and fault-isolation procedures on numerous users of the data-over-cable and other services.
+
+For the interpretation of harmful impact, see clause 4.2.2.
+
+### 4.2.4 Cable system terminal devices
+
+The CM MUST meet and SHOULD exceed all applicable national regulations for cable system termination devices and cable-ready consumer equipment. None of these national specific requirements may be used to relax any of the specifications contained elsewhere within this Recommendation.
+
+## 4.3 RF channel assumptions
+
+The data-over-cable system, configured with at least one set of defined physical-layer parameters (e.g., modulation, forward error correction, modulation rate, etc.) from the range of configuration settings described in this Recommendation, MUST be interoperable on cable networks having characteristics defined in this clause in such a manner that the forward error correction provides for
+
+equivalent operation in a cable system both with and without the impaired channel characteristics described below.
+
+### 4.3.1 Transmission downstream
+
+The RF channel transmission characteristics of the cable network in the downstream direction are described in Table 4-1. These numbers assume total average power of a digital signal in a 6-MHz channel bandwidth for carrier levels unless indicated otherwise. For impairment levels, the numbers in Table 4-1 assume average power in a bandwidth in which the impairment levels are measured in a standard manner for cable TV system. For analogue signal levels, the numbers in Table 4-1 assume peak envelope power in a 6-MHz channel bandwidth. All conditions are present concurrently. No combination of the following parameters will exceed any stated interface limit defined elsewhere in this Recommendation.
+
+**Table 4-1 – Assumed downstream RF channel transmission characteristics  
+(see Note 1)**
+
+| Parameter                                                                                         | Value                                                                                                                                                                        |
+|---------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Frequency range                                                                                   | Cable system normal downstream operating range is from 50 MHz to as high as 860 MHz. However, the values in this table apply only at frequencies $\geq 88$ MHz.              |
+| RF channel spacing (design bandwidth)                                                             | 6 MHz                                                                                                                                                                        |
+| Transit delay from headend to most distant customer                                               | $\leq 0.800$ ms (typically much less)                                                                                                                                        |
+| Carrier-to-noise ratio in a 6 MHz band                                                            | Not less than 35 dB (see Notes 2 and 3)                                                                                                                                      |
+| Carrier-to-composite triple beat distortion ratio                                                 | Not less than 41 dB (see Notes 2 and 3)                                                                                                                                      |
+| Carrier-to-composite second order distortion ratio                                                | Not less than 41 dB (see Notes 2 and 3)                                                                                                                                      |
+| Carrier-to-cross-modulation ratio                                                                 | Not less than 41 dB (see Notes 2 and 3)                                                                                                                                      |
+| Carrier-to-any other discrete interference (ingress)                                              | Not less than 41 dB (see Notes 2 and 3)                                                                                                                                      |
+| Amplitude ripple                                                                                  | 3 dB within the design bandwidth (see Note 2)                                                                                                                                |
+| Group delay ripple in the spectrum occupied by the CMTS                                           | 75 ns within the design bandwidth (see Note 2)                                                                                                                               |
+| Micro-reflections bound for dominant echo                                                         | $-20$ dBc @ $\leq 1.5$ $\mu\text{s}$ ,<br>$-30$ dBc @ $> 1.5$ $\mu\text{s}$ ,<br>$-10$ dBc @ $\leq 0.5$ $\mu\text{s}$ ,<br>$-15$ dBc @ $\leq 1.0$ $\mu\text{s}$ (see Note 2) |
+| Carrier hum modulation                                                                            | Not greater than $-26$ dBc (5%) (see Note 2)                                                                                                                                 |
+| Burst noise                                                                                       | Not longer than 25 $\mu\text{s}$ at a 10-Hz average rate (see Note 2)                                                                                                        |
+| Maximum analogue video carrier level at the CM input                                              | 17 dBmV                                                                                                                                                                      |
+| Maximum number of analogue carriers                                                               | 121                                                                                                                                                                          |
+| NOTE 1 – Transmission is from the headend combiner to the CM input at the customer location.      |                                                                                                                                                                              |
+| NOTE 2 – Measurement methods defined in [b-NCTA] or [b-CableLabs2].                               |                                                                                                                                                                              |
+| NOTE 3 – Measured relative to a QAM signal that is equal to the nominal video level in the plant. |                                                                                                                                                                              |
+
+### 4.3.2 Transmission upstream
+
+The RF channel transmission characteristics of the cable network in the upstream direction are described in Table 4-2. All conditions are present concurrently. No combination of the following parameters will exceed any stated interface limit defined elsewhere in this Recommendation.
+
+**Table 4-2 – Assumed upstream RF channel transmission characteristics  
+(see Note 1)**
+
+| Parameter                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         | Value                                                                                                             |
+|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------|
+| Frequency range                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 5 to 42 MHz edge to edge                                                                                          |
+| Transit delay from the most distant CM to the nearest CM or CMTS                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | $\leq 0.800$ ms (typically much less)                                                                             |
+| Carrier-to-interference plus ingress (the sum of noise, distortion, common-path distortion and cross-modulation and the sum of discrete and broadband ingress signals, impulse noise excluded) ratio                                                                                                                                                                                                                                                                                                                                              | Not less than 25 dB (Note 2)                                                                                      |
+| Carrier hum modulation                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | Not greater than $-23$ dBc (7.0%)                                                                                 |
+| Burst noise                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | Not longer than $10$ $\mu\text{s}$ at a 1-kHz average rate for most cases (Notes 3 and 4)                         |
+| Amplitude ripple 5-42 MHz                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         | 0.5 dB/MHz                                                                                                        |
+| Group delay ripple 5-42 MHz                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | 200 ns/MHz                                                                                                        |
+| Micro-reflections – single echo                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | $-10$ dBc @ $\leq 0.5$ $\mu\text{s}$<br>$-20$ dBc @ $\leq 1.0$ $\mu\text{s}$<br>$-30$ dBc @ $> 1.0$ $\mu\text{s}$ |
+| Seasonal and diurnal reverse gain (loss) variation                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | Not greater than 14 dB min to max                                                                                 |
+| NOTE 1 – Transmission is from the CM output at the customer location to the headend.<br>NOTE 2 – Ingress avoidance or tolerance techniques may be used to ensure operation in the presence of time-varying discrete ingress signals that could be as high as 10 dBc. The ratios are guaranteed only within the digital carrier channels.<br>NOTE 3 – Amplitude and frequency characteristics sufficiently strong to partially or wholly mask the data carrier.<br>NOTE 4 – Impulse noise levels more prevalent at lower frequencies ( $<15$ MHz). |                                                                                                                   |
+
+#### 4.3.2.1 Availability
+
+Typical cable network availability is considerably greater than 99%.
+
+## 4.4 Transmission levels
+
+The nominal power level of the downstream CMTS signal(s) within a 6-MHz channel is targeted to be in the range  $-10$  dBc to  $-6$  dBc relative to analogue video carrier level and will normally not exceed analogue video carrier level. The nominal power level of the upstream CM signal(s) will be as low as possible to achieve the required margin above noise and interference. Uniform power loading per unit bandwidth is commonly followed in setting upstream signal levels, with specific levels established by the cable network operator to achieve the required carrier-to-noise and carrier-to-interference ratios.
+
+## **4.5 Frequency inversion**
+
+There will be no frequency inversion in the transmission path in either the downstream or upstream directions, i.e., a positive change in frequency at the input to the cable network will result in a positive change in frequency at the output.
+
+# **5 Communication protocols**
+
+This clause provides a high-level overview of the communication protocols that must be used in the data-over-cable system. Detailed specifications for the physical media dependent, downstream transmission, and media access control sublayers are provided in clauses 6, 7, and 8, respectively.
+
+## **5.1 Protocol stack**
+
+The CM and CMTS operate as forwarding agents and also as end-systems (hosts). The protocol stacks used in these modes differ as shown below.
+
+The principal function of the cable modem system is to transmit Internet protocol (IP) packets transparently between the headend and the subscriber location. Certain management functions also ride on IP, so that the protocol stack on the cable network is as shown in Figure 5-1 (this does not restrict the generality of IP transparency between the headend and the customer). These management functions include, for example, supporting spectrum management functions and the downloading of software.
+
+### **5.1.1 CM and CMTS as hosts**
+
+CMs and CMTSs operate as IP and LLC hosts in terms of [IEEE 802] for communication over the cable network. The protocol stack at the CM and CMTS RF interfaces is shown in Figure 5-1.
+
+![Figure 5-1: Protocol stack on the RF interface. The diagram shows a vertical stack of protocol layers. At the top, three boxes labeled 'SNMP', 'TFTP', and 'DHCP' are connected to a single wide box labeled 'UDP'. Below 'UDP' is a box labeled 'IP, ICMP'. To the right of 'IP, ICMP' is a box labeled 'ARP', connected by a horizontal line. Below 'IP, ICMP' is a box labeled 'LLC/DIX'. Below 'LLC/DIX' is a box labeled 'Link security'. Below 'Link security' is a box labeled 'MAC'. Below 'MAC' is a box labeled 'Transmission convergence (downstream only)'. At the bottom is a box labeled 'PMD'.](11edb7fcedf09ac6a817f8d7b8c61eec_img.jpg)
+
+Figure 5-1: Protocol stack on the RF interface. The diagram shows a vertical stack of protocol layers. At the top, three boxes labeled 'SNMP', 'TFTP', and 'DHCP' are connected to a single wide box labeled 'UDP'. Below 'UDP' is a box labeled 'IP, ICMP'. To the right of 'IP, ICMP' is a box labeled 'ARP', connected by a horizontal line. Below 'IP, ICMP' is a box labeled 'LLC/DIX'. Below 'LLC/DIX' is a box labeled 'Link security'. Below 'Link security' is a box labeled 'MAC'. Below 'MAC' is a box labeled 'Transmission convergence (downstream only)'. At the bottom is a box labeled 'PMD'.
+
+J.122\_F5-1
+
+**Figure 5-1 – Protocol stack on the RF interface**
+
+The CM and CMTS MUST function as IP hosts. As such, the CM and CMTS MUST support IP and ARP over DIX link-layer framing ("DIX link-layer framing" refers to the "type interpretation" of the length/type field in [ISO/IEC 8802-3]). The CMTS MUST NOT transmit frames that are smaller than the DIX 64-byte minimum on a downstream channel<sup>1</sup>. However, the CM MAY transmit frames that are smaller than the DIX 64-byte minimum on an upstream channel.
+
+The CM and CMTS MAY also support IP and ARP over SNAP framing [RFC 1042].
+
+The CM and CMTS also MUST function as LLC hosts. As such, the CM and CMTS MUST respond appropriately to TEST and XID requests per [ISO/IEC 8802-2].
+
+### **5.1.2 Data forwarding through the CM and CMTS**
+
+#### **5.1.2.1 General**
+
+Data forwarding through the CMTS MAY be transparent bridging<sup>2</sup>, or MAY employ network-layer forwarding (routing, IP switching) as shown in Figure 5-2.
+
+<sup>1</sup> Except as a result of payload header suppression. Refer to clause 10.4.
+
+<sup>2</sup> With the exception that, for packet PDUs less than 64 bytes to be forwarded from the upstream RFI, a CMTS MUST pad out the packet PDU and recompute the CRC.
+
+![Figure 5-2: Data forwarding through the CM and CMTS. This diagram compares the protocol stacks of a CMTS and a CM. The CMTS stack shows IP at the top, followed by a Data link layer with Forwarding, 802.2/DIX LLC, Link security, and Cable MAC. Below this is the PHY layer with DS TC layer, Upstream Cable PMD, and Cable PMD. It connects to a CMTS-NSI interface. The CM stack shows IP at the top, followed by a Data link layer with 802.2/DIX LLC, Transparent bridging, Link security, and Cable MAC. Below this is the PHY layer with DS TC layer, Upstream Cable PMD, and Cable PMD, which connects to a CMCI interface. A central 'Cable network transmission' line connects the two stacks. Reference J.122_F5-2 is noted.](c494cd874a082a97b50b3c4d3938f467_img.jpg)
+
+Figure 5-2: Data forwarding through the CM and CMTS. This diagram compares the protocol stacks of a CMTS and a CM. The CMTS stack shows IP at the top, followed by a Data link layer with Forwarding, 802.2/DIX LLC, Link security, and Cable MAC. Below this is the PHY layer with DS TC layer, Upstream Cable PMD, and Cable PMD. It connects to a CMTS-NSI interface. The CM stack shows IP at the top, followed by a Data link layer with 802.2/DIX LLC, Transparent bridging, Link security, and Cable MAC. Below this is the PHY layer with DS TC layer, Upstream Cable PMD, and Cable PMD, which connects to a CMCI interface. A central 'Cable network transmission' line connects the two stacks. Reference J.122\_F5-2 is noted.
+
+**Figure 5-2 – Data forwarding through the CM and CMTS**
+
+Data forwarding through the CM is link-layer transparent bridging, as shown in Figure 5-2. Forwarding rules are similar to [b-ISO/IEC 10038] with the modifications described in clauses 5.1.2.2 and 5.1.2.3. This allows the support of multiple network layers.
+
+Forwarding of IP traffic **MUST** be supported. Other network layer protocols **MAY** be supported. The ability to restrict the network layer to a single protocol such as IP **MUST** be supported.
+
+The IEEE 802.1D spanning tree protocol of [b-ISO/IEC 10038], with the modifications described in Annex E, **MAY** be supported by CMs intended for residential use. CMs intended for commercial use **MUST** support this version of spanning tree. CMs and CMTSs **MUST** include the ability to filter (and disregard) IEEE 802.1D BPDUs.
+
+This Recommendation assumes that CMs intended for residential use will not be connected in a configuration which would create network loops such as that shown in Figure 5-3.
+
+![Figure 5-3: Example condition for network loops. This diagram shows a network topology. A 'Cable network' at the top connects to a 'CMTS'. The 'CMTS' connects to a bus that branches to two 'CM' units, labeled 'CM #1' and 'CM #2'. Both 'CM #1' and 'CM #2' connect to a common bus labeled 'Local ISO 8802 network'. A 'CPE' unit is connected to this 'Local ISO 8802 network' bus. Reference J.122_F5-3 is noted.](98e54d5540b2efe3e24af3cf936bc4ea_img.jpg)
+
+Figure 5-3: Example condition for network loops. This diagram shows a network topology. A 'Cable network' at the top connects to a 'CMTS'. The 'CMTS' connects to a bus that branches to two 'CM' units, labeled 'CM #1' and 'CM #2'. Both 'CM #1' and 'CM #2' connect to a common bus labeled 'Local ISO 8802 network'. A 'CPE' unit is connected to this 'Local ISO 8802 network' bus. Reference J.122\_F5-3 is noted.
+
+**Figure 5-3 – Example condition for network loops**
+
+Although provisions exist in this Recommendation for frames to be passed from a higher-layer entity to be forwarded by the cable modem, these frames **MUST** be treated identically to frames arriving at the CPE port. In particular, all of the forwarding rules defined in clause 5.1.2.3 **MUST** apply to these frames
+
+#### 5.1.2.2 CMTS forwarding rules
+
+At the CMTS, if link-layer forwarding is used, then it MUST conform to the following general IEEE 802.1D guidelines:
+
+- Link-layer frames MUST NOT be duplicated.
+- Stale frames (those that cannot be delivered in a timely fashion) MUST be discarded.
+- Link-layer frames, on a given service flow (refer to clause 8.1.2.3), MUST be delivered in the order they are received.
+
+The address-learning and -aging mechanisms used are vendor-dependent.
+
+If network-layer forwarding is used, then the CMTS should conform to IETF router requirements [b-RFC 1812] with respect to its CMTS-RFI and CMTS-NSI interfaces.
+
+Conceptually, the CMTS forwards data packets at two abstract interfaces: between the CMTS-RFI and the CMTS-NSI, and between the upstream and downstream channels. The CMTS MAY use any combination of link-layer (bridging) and network-layer (routing) semantics at each of these interfaces. The methods used at the two interfaces need not be the same.
+
+Forwarding between the upstream and downstream channels within a MAC layer differs from traditional LAN forwarding in that:
+
+- A single channel is simplex, and cannot be considered a complete interface for most protocol (e.g., 802.1D spanning tree, routing information protocol per [b-RFC 1058]) purposes.
+- Upstream channels are essentially point-to-point, whereas downstream channels are shared-media.
+- Policy decisions may override full connectivity.
+
+For these reasons, an abstract entity called the MAC forwarder exists within the CMTS to provide connectivity between stations within a MAC domain (see clause 5.2).
+
+#### 5.1.2.3 CM forwarding rules
+
+Data forwarding through the CM is link-layer bridging with the following specific rules.
+
+##### 5.1.2.3.1 CPE MAC address acquisition
+
+- The CM MUST acquire Ethernet MAC addresses of connected CPE devices, either from the provisioning process or from learning, until the CM acquires its maximum number of CPE MAC addresses (a device-dependent value). Once the CM acquires its maximum number of CPE MAC addresses, then newly discovered CPE MAC addresses MUST NOT replace previously acquired addresses. The CM must support acquisition of at least one CPE MAC address.
+- The CM MUST allow configuration of CPE addresses during the provisioning process (up to its maximum number of CPE addresses) to support configurations in which learning is not practical nor desired.
+- Addresses provided during the CM provisioning MUST take precedence over learned addresses.
+- CPE addresses MUST NOT be aged out.
+- In order to allow modification of user MAC addresses or movement of the CM, addresses are not retained in non-volatile storage. On a CM reset (e.g., power cycle), all provisioned and learned addresses MUST be discarded.
+
+##### 5.1.2.3.2 Forwarding
+
+CM forwarding in both directions MUST conform to the following general IEEE 802.1D guidelines:
+
+- Link-layer frames MUST NOT be duplicated.
+- Stale frames (those that cannot be delivered in a timely fashion) MUST be discarded.
+- Link-layer frames MUST be delivered in the order that they are received on a given service flow (refer to clause 8.1.2.3). In the upstream direction, the CM may perform one or more frame/packet processing functions on frames received from the CMCI prior to classifying them to a service flow. In the downstream direction, the CM may perform one or more frame/packet processing functions on frames received from the HFC prior to transmitting them on the CMCI. Example processing functions include: DOCSIS protocol filtering as specified in [DOCS5] clause 7.3, a policy-based filtering service as described in clause 10.1.6.1 and Appendix I, and priority-based queuing to support 802.1P/Q services.
+- Link-layer frames, on a given service flow (refer to clause 8.1.2.3), MUST be delivered in the order they are received.
+
+Cable-network-to-CMCI forwarding MUST follow the following specific rules:
+
+- Frames addressed to unknown destinations MUST NOT be forwarded from the cable port to the CPE ports.
+- Broadcast frames MUST be forwarded to the CPE ports, unless they are from source addresses which are provisioned or learned as supported CPE devices, in which case they MUST NOT be forwarded.
+- The forwarding of multicast is controlled by administratively set filters and by either IGMP (refer to clause 5.3.1) or static provisioning (refer to clause C.1.2.12). Multicast frames MUST NOT be forwarded unless both filtering and either IGMP or static multicast provisioning are in a permissive state.
+
+CPE-to-cable-network forwarding MUST follow the following specific rules:
+
+- Frames addressed to unknown destinations MUST be forwarded from all CPE ports to the cable port.
+- Broadcast frames MUST be forwarded to the cable port.
+- Multicast frames MUST be forwarded to the cable port in accordance with filtering configuration settings specified by the cable operator's operations and business support systems.
+- Frames from source addresses other than those provisioned or learned as supported CPE devices MUST NOT be forwarded.
+- Other (non-supported) CPE source addresses MUST be learned from all CPE ports and this information used to filter local traffic as in a traditional learning bridge.
+- Frames addressed to destination addresses that are learned from all CPE ports MUST be filtered as local traffic.
+
+## 5.2 The MAC forwarder
+
+The MAC forwarder is a MAC sublayer that resides on the CMTS just below the MAC service access point (MSAP) interface, as shown in Figure 5-4. It is responsible for delivering upstream frames to:
+
+- one or more downstream channels;
+- the MSAP interface.
+
+![Diagram of a MAC forwarder architecture within a CMTS. The CMTS contains an RFI-NSI forwarding process and a Host IP stack (including LLC and 802.2/DIX). These are connected to a MAC service access point (MSAP) interface. Below the MSAP, a dashed box labeled 'MAC' contains a MAC forwarder and a Link security sublayer. The MAC forwarder is connected to the MSAP and to multiple Upstream and downstream channels. A CMTS-NSI block is also shown, connected to the RFI-NSI forwarding process and the MAC forwarder.](7ae836e598020d937ed1478c2ef13025_img.jpg)
+
+The diagram illustrates the internal architecture of a CMTS (Cable Modem Termination System). At the top, two boxes represent the 'RFI-NSI forwarding process' and the 'Host IP stack, including LLC and 802.2/DIX'. Both are connected to a horizontal line representing the 'MAC service access point (MSAP) interface'. Below this interface, a dashed box labeled 'MAC' contains two stacked boxes: 'MAC forwarder' on top and 'Link security' on the bottom. The MAC forwarder is connected to the MSAP interface and has multiple arrows pointing down to 'Upstream and downstream channels'. To the left of the MAC forwarder, a box labeled 'CMTS-NSI' is connected to the 'RFI-NSI forwarding process' and also to the 'MAC forwarder'.
+
+Diagram of a MAC forwarder architecture within a CMTS. The CMTS contains an RFI-NSI forwarding process and a Host IP stack (including LLC and 802.2/DIX). These are connected to a MAC service access point (MSAP) interface. Below the MSAP, a dashed box labeled 'MAC' contains a MAC forwarder and a Link security sublayer. The MAC forwarder is connected to the MSAP and to multiple Upstream and downstream channels. A CMTS-NSI block is also shown, connected to the RFI-NSI forwarding process and the MAC forwarder.
+
+**Figure 5-4 – MAC forwarder**
+
+In Figure 5-4, the LLC sublayer and link security sublayers of the upstream and downstream channels on the cable network terminate at the MAC forwarder.
+
+The MSAP interface user may be the NSI-RFI forwarding process or the CMTS's host protocol stack.
+
+Delivery of frames may be based on data-link-layer (bridging) semantics, network-layer (routing) semantics, or some combination. Higher-layer semantics may also be employed (e.g., filters on UDP port numbers). The CMTS MUST provide IP connectivity between hosts attached to cable modems, and must do so in a way that meets the expectations of Ethernet-attached customer equipment. For example, the CMTS must either forward ARP packets or it must facilitate a proxy ARP service. The CMTS MAC Forwarder MAY provide service for non-IP protocols.
+
+Note that there is no requirement that all upstream and downstream channels be aggregated under one MSAP as shown above. The vendor could just as well choose to implement multiple MSAPs, each with a single upstream and downstream channel.
+
+### 5.2.1 Rules for data-link-layer forwarding
+
+The requirements in this clause apply if the MAC forwarder is implemented using only data-link-layer semantics.
+
+Delivery of frames is dependent on the destination address within the frame. The means of learning the location of each address is vendor-dependent, and MAY include:
+
+- transparent-bridging-like source-address learning and aging;
+- gleaning from MAC registration request messages;
+- administrative means.
+
+If the destination address of a frame is unicast, and that address is associated with a particular downstream channel, then the frame MUST be forwarded to that channel<sup>3</sup>.
+
+<sup>3</sup> Vendors may implement extensions, similar to static addresses in 802.1D/ISO/IEC 10038 bridging, that cause such frames to be filtered or handled in some other manner.
+
+If the destination address of a frame is unicast, and that address is known to reside on the other (upper) side of the MSAP interface, then the frame **MUST** be delivered to the MSAP interface.
+
+If the destination address is broadcast, multicast<sup>4</sup>, or unknown, the frame **MUST** be delivered to both the MSAP and to all downstream channels (with the exception of the multicast forwarding rules in clause 5.3.1.2).
+
+Delivery rules are similar to those for transparent bridging:
+
+- Frames **MUST NOT** be duplicated.
+- Frames that cannot be delivered in a timely fashion **MUST** be discarded.
+- The frame check sequence **SHOULD** be preserved rather than regenerated.
+- Frames, on a given service flow (refer to clause 8.1.2.3), **MUST** be delivered in the order they are received.
+
+## 5.3 Network layer
+
+As stated above, the purpose of the data-over-cable system is to transport IP traffic transparently through the system.
+
+The network layer protocol is the Internet protocol (IP) version 4, as defined in [RFC 791], and migrating to IP version 6.
+
+This Recommendation imposes no requirements for reassembly of IP packets.
+
+### 5.3.1 Requirements for IGMP management
+
+There are two basic modes of IGMP capability that are applicable to a DOCS 2.0 device (CMTS and CM). The first mode is a *passive* operation in which the device selectively forwards IGMP based upon the known state of multicast session activity on the subscriber side (an example of this is described in Appendix V). In *passive* mode, the device derives its IGMP timers based on the rules specified in [DOCS11]. The second mode is an *active* operation in which the device terminates and initiates IGMP based upon the known state of multicast session activity on the subscriber side. One example of the latter, active, mode is commonly referred to as an IGMP-proxy implementation side (as described in [b-ID-IGMP]). A more complete example of an active IGMP device is that of a multicast router.
+
+Active and passive IGMP devices **MUST** support IGMP v2 [RFC 2236].
+
+#### 5.3.1.1 IGMP timer requirements
+
+The following IGMP timer requirements apply only when the device (CMTS/CM) is operating in passive IGMP mode:
+
+- The device **MUST NOT** require any specific configuration for the associated multicast timer values and **MUST** be capable of adhering to the timers specified in this clause.
+- The device **MAY** provide configuration control that overrides the default values of these timers.
+- The device **MUST** derive the membership query interval by looking at the inter-arrival times of the membership query messages. Formally: If  $n < 2$ ,  $MQI = 125$ , else  $MQI = \text{MAX}(125, MQ_n - MQ_{n-1})$ , where  $MQI$  is the membership query interval in seconds,  $n$  is the number of membership queries seen, and  $MQ_n$  is the epoch time at which the  $n$ th membership query was seen to the nearest second.
+
+---
+
+<sup>4</sup> All multicasts, including 802.1D/ISO 10038 spanning tree bridge BPDUs, **MUST** be forwarded.
+
+- The query response interval is carried in the membership query packet. The query response interval MUST be assumed to be 10 seconds if not otherwise set (or set to 0) in the membership query packet.
+
+#### 5.3.1.2 CMTS rules
+
+- If link-layer forwarding of multicast packets is used, the CMTS MUST forward all membership queries on all downstream channels using the appropriate 802.3 multicast group (e.g., 01:00:5E:xx:xx:xx where xx:xx:xx are the low-order 23 bits of the multicast address expressed in hex notation. Refer to [b-IMA]).
+- The CMTS MUST forward the first copy of solicited and unsolicited membership reports for any given group received on its upstream RF interface to all of its downstream RF interfaces. However, if membership is managed on a per downstream RF interface basis, membership reports and IGMP v2 leave messages MAY be forwarded only on the downstream interface to which the reporting CPE's CM is connected.
+- The CMTS SHOULD suppress the transmission of additional membership reports (for any given group) downstream for at least the query response interval. If the CMTS uses data-link-layer forwarding, it MUST also forward the membership report out all appropriate network side interfaces.
+- The CMTS SHOULD suppress the downstream transmission of traffic to any IP multicast group that does not have subscribers on that downstream RF interface (subject to any administrative controls).
+- If the CMTS performs network-layer forwarding of multicast packets, it MUST support active IGMP mode.
+- If link-layer forwarding of multicast packets is used, the CMTS SHOULD support passive IGMP mode and MAY support Active IGMP mode.
+
+#### 5.3.1.3 CM rules
+
+The CM MUST support IGMP with the cable-specific rules specified in this clause.
+
+The CM MUST implement the passive IGMP mode. Additionally, the CM MAY implement the active IGMP mode. If it implements the active IGMP mode, the CM MUST support a capability to switch between modes.
+
+##### 5.3.1.3.1 Multicast forwarding requirements
+
+The following requirements apply to both passive and active modes of IGMP operations:
+
+- The CM MUST NOT forward membership queries from its CPE interface to its RF interface.
+- The CM MUST NOT forward membership reports or IGMP v2 leaves received on its RF interface to its CPE interface.
+- The CM MUST NOT forward multicast traffic from its RF interface to its CPE interface unless a device on its CPE interface is a member of that IP multicast group.
+- The CM MUST forward multicast traffic from its CPE interface to its RF interface unless administratively (via configuration or other mechanism) prohibited.
+- As a result of receiving a membership report on its CPE interface, the CM MUST begin forwarding traffic for the appropriate IP multicast group. The CM MUST stop forwarding multicast traffic from the RF to the CPE side whenever the CM has not received a membership report from the CPE side for more than the membership interval, which is  $(2 \times MQI) + QRI$ , where MQI is the membership query interval and QRI is the query response interval.
+
+- The CM MAY stop forwarding traffic from the RF to the CPE side for a particular multicast group prior to the expiration of the membership interval (see above) if it can determine (for example, via an IGMP LEAVE message and the appropriate protocol exchange) that there are no CPE devices subscribed to that particular group.
+
+The following requirements apply only when the CM is operating in passive IGMP mode:
+
+- The CM MUST forward traffic for the ALL-HOSTS multicast group from its RF interface to its CPE interface unless administratively prohibited. The CPE MUST always be considered a member of this group. In particular, the CM MUST forward ALL-HOSTS group queries that pass permit filters on its RF interface to its CPE interface.
+- Upon receiving a membership report on its CPE interface, the CM MUST start a random timer between 0 and 3 seconds. During this time period, the CM MUST discard any additional membership reports received in its CPE interface for the associated multicast group. If the CM receives a membership report on its HFC interface for the associated multicast group, the CM MUST discard the membership report received on its CPE interface. If the random timer expires without the reception of a membership report on the CMs HFC interface, the CM MUST transmit the membership report received on its CPE interface.
+
+The following requirements apply only when the CM is operating in active IGMP mode:
+
+- The CM MUST implement the host portion of the IGMP v2 protocol [RFC 2236] on its RF interface for CPEs with active groups and MUST NOT act as a querier on its RF interface.
+- The CM MUST act as an IGMP v2 querier on its CPE interface.
+- If the CM has received a membership report on its downstream RF interface for groups active on the CMs CPE interface within the query response interval, it MUST suppress transmission on its upstream RF interface of such membership reports.
+- The CM MUST suppress all subsequent membership reports for this group until such time as the CM receives a membership query (general or specific to this group) on its RF interface or a IGMP v2 leave is received for this group from the CPE interface.
+- The CM MUST treat unsolicited membership reports (IGMP JOINS) from its CPE interface as a response to a membership query received on its RF interface. Upon receipt of this unsolicited JOIN from its CPE interface, the CM MUST start a random timer according to the host state diagram, specified in [RFC 2236], and MUST use a query response interval of 3 seconds. As specified above, if the CM receives a membership report on its RF interface for this group during this random time period, it MUST suppress transmission of this join on its upstream RF interface.
+- On startup, the CM SHOULD send one or more general queries on its CPE interface (as described in [RFC 2236]) in order to quickly and reliably determine membership information for attached CPEs.
+
+NOTE – Nothing in this clause would prohibit the CM from being specifically configured to not forward certain multicast traffic as a matter of network policy.
+
+## 5.4 Above the network layer
+
+The subscribers will be able to use the transparent IP capability as a bearer for higher-layer services. Use of these services will be transparent to the CM.
+
+In addition to the transport of user data, there are several network management and operation capabilities which depend upon the network layer. These include:
+
+- Simple network management protocol (SNMP) [RFC 1157] MUST be supported for network management.
+
+- Trivial file transfer protocol (TFTP) [RFC 1350], a file transfer protocol, MUST be supported for downloading operational software and configuration information, as modified by TFTP timeout interval and transfer size options [RFC 2349].
+- Dynamic host configuration protocol (DHCP) [RFC 2131], a framework for passing configuration information to hosts on a TCP/IP network, MUST be supported.
+- Time protocol, [RFC 868], MUST be supported to obtain the time of day.
+
+DHCP, TFTP and ToD client messages generated by the CM MUST only be sent via the RF Interface. DHCP, TFTP and ToD client messages include DHCPDISCOVER, DHCPREQUEST, DHCPDECLINE, DHCPRELEASE, DHCPINFORM, TFTP-RRQ, TFTP-ACK and ToD request.
+
+The CM's DHCP, TFTP and ToD client MUST ignore DHCP, TFTP and ToD server messages received on the CMCI port. DHCP, TFTP and ToD server messages include: DHCPOFFER, DHCPACK, DHCPNAK, TFTP-DATA and ToD time message.
+
+## 5.5 Data link layer
+
+The data link layer is divided into sublayers in accordance with [IEEE 802], with the addition of link-layer security in accordance with [DOCS8]. The sublayers, from the top, are:
+
+- logical link control (LLC) sublayer (class 1 only);
+- link-layer security sublayer;
+- media access control (MAC) sublayer.
+
+### 5.5.1 LLC sublayer
+
+The LLC sublayer MUST be provided in accordance with [ISO/IEC 10039]. Address resolution MUST be used as defined in [RFC 826]. The MAC-to-LLC service definition is specified in [ISO/IEC 10039].
+
+### 5.5.2 Link-layer security sublayer
+
+Link-layer security MUST be provided in accordance with [DOCS8].
+
+### 5.5.3 MAC sublayer
+
+The MAC sublayer defines a single transmitter for each downstream channel – the CMTS. All CMs listen to all frames transmitted on the downstream channel upon which they are registered and accept those where the destinations match the CM itself or CPEs reached via the CMCI port. CMs can communicate with other CMs only through the CMTS.
+
+The upstream channel is characterized by many transmitters (CMs) and one receiver (the CMTS). Time in the upstream channel is slotted, providing for time division multiple access at regulated time ticks. The CMTS provides the time reference and controls the allowed usage for each interval. Intervals may be granted for transmissions by particular CMs, or for contention by all CMs. CMs may contend to request transmission time. To a limited extent, CMs may also contend to transmit actual data. In both cases, collisions can occur and retries are used.
+
+Clause 8 describes the MAC-sublayer messages from the CMTS which direct the behaviour of the CMs on the upstream channel, as well as messaging from the CMs to the CMTS.
+
+#### 5.5.3.1 MAC service definition
+
+The MAC sublayer service definition is in Appendix I.
+
+## 5.6 Physical layer
+
+The physical (PHY) layer is comprised of two sublayers:
+
+- transmission convergence sublayer (present in the downstream direction only);
+
+- physical media dependent (PMD) sublayer.
+
+### **5.6.1 Downstream transmission convergence sublayer**
+
+The downstream transmission convergence sublayer exists in the downstream direction only. It provides an opportunity for additional services over the physical-layer bitstream. These additional services might include, for example, digital video. Definition of any such additional services is beyond the scope of this Recommendation.
+
+This sublayer is defined as a continuous series of 188-byte MPEG [ITU-T H.222.0] packets, each consisting of a 4-byte header followed by 184 bytes of payload. The header identifies the payload as belonging to the data-over-cable MAC. Other values of the header may indicate other payloads. The mixture of payloads is arbitrary and controlled by the CMTS.
+
+The downstream transmission convergence sublayer is defined in clause 7.
+
+### **5.6.2 PMD sublayer**
+
+The physical media dependent sublayer is defined in clause 6.
+
+#### **5.6.2.1 Interface points**
+
+Three RF interface points are defined at the PMD sublayer:
+
+- downstream output on the CMTS;
+- upstream input on the CMTS;
+- cable in/out at the cable modem.
+
+Separate downstream output and upstream input interfaces on the CMTS are required for compatibility with typical downstream and upstream signal combining and splitting arrangements in headends.
+
+# **6 Physical media dependent sublayer specification**
+
+## **6.1 Scope**
+
+This Recommendation defines the electrical characteristics and signal processing operations for a cable modem (CM) and cable modem termination system (CMTS). It is the intent of this Recommendation to define an interoperable CM and CMTS such that any implementation of a CM can work with any CMTS. It is not the intent of this Recommendation to imply any specific implementation.
+
+This clause applies to the first technology option referred to in clause 1.1. For the second and third options, refer to Annexes F and J, respectively.
+
+Whenever any reference in this clause to spurious emissions conflicts with any legal requirement for the area of operation, the latter shall take precedence.
+
+## **6.2 Upstream**
+
+### **6.2.1 Overview**
+
+The upstream physical media dependent (PMD) sublayer uses a FDMA/TDMA (herein called TDMA mode) or FDMA/TDMA/S-CDMA (herein called S-CDMA mode) burst type format, which provides six modulation rates and multiple modulation formats. The use of TDMA or S-CDMA mode is configured by the CMTS via MAC messaging.
+
+Frequency division multiple access (FDMA) indicates that multiple RF channels are assigned in the upstream band. A CM transmits on a single RF channel unless reconfigured to change channels. Time division multiple access (TDMA) indicates that upstream transmissions have a burst nature. A
+
+given RF channel is shared by multiple CMs via the dynamic assignment of time slots. Synchronous code division multiple access (S-CDMA) indicates that multiple CMs can transmit simultaneously on the same RF channel and during the same TDMA time slot, while being separated by different orthogonal codes.
+
+In this Recommendation, the following naming conventions are used. For TDMA, the term "modulation rate" refers to the RF channel symbol rate (160 to 5120 ksymb/s). For S-CDMA, the term "chip rate", which is the modulation rate (1280 to 5120 kHz) of a single bit of the S-CDMA spreading code, may be used interchangeably with "modulation rate". The "modulation interval" is the symbol period (TDMA mode) or chip period (S-CDMA mode) and is the reciprocal of the modulation rate. At the output of the spreader, a group of 128 chips which comprise a single S-CDMA spreading code, and are the result of spreading a single information (QAM constellation) symbol is referred to as a "spread symbol". The period of a spread symbol (128 chips) is called a "spreading interval." A "burst" is a physical RF entity that contains a single preamble plus data, and (in the absence of preceding and following bursts) exhibits RF energy ramp-up and ramp-down.
+
+In some cases logical zeros are used to pad data blocks; this indicates data with zero-valued binary bits, which result in non-zero transmitted RF energy. In other cases a numerical zero is used; this denotes, for example, symbols that result in zero transmitted RF energy (after ramp-up and ramp-down are taken into account).
+
+The modulation format includes pulse shaping for spectral efficiency, is carrier-frequency agile, and has selectable output power level.
+
+Each burst supports a flexible modulation order, modulation rate, preamble, randomization of the payload, and programmable FEC encoding.
+
+All of the upstream transmission parameters associated with burst transmission outputs from the CM are configurable by the CMTS via MAC messaging. Many of the parameters are programmable on a burst-by-burst basis.
+
+The PMD sublayer can support a near-continuous mode of transmission, wherein ramp-down of one burst MAY overlap the ramp-up of the following burst, so that the transmitted envelope is never zero. In TDMA mode, the system timing of the TDMA transmissions from the various CMs MUST provide that the centre of the last symbol of one burst and the centre of the first symbol of the preamble of an immediately following burst are separated by at least the duration of five symbols. The guard band MUST be greater than or equal to the duration of five symbols plus the maximum timing error. Timing error is contributed by both the CM and CMTS. CM timing performance is specified in clause 6.2.19. Maximum timing error and guard band may vary with CMTSs from different vendors. The term guard time is similar to the guard band, except that it is measured from the end of the last symbol of one burst to the beginning of the first symbol of the preamble of an immediately following burst. Thus, the guard time is equal to the guard band - 1.
+
+The PMD sublayer also supports a synchronous mode of transmission when using S-CDMA, wherein ramp-down of one burst MAY completely overlap the ramp-up of the following burst, so that the transmitted envelope is never zero. There is no guard time for transmission on S-CDMA channels. The system timing of the S-CDMA transmissions from the various CMs MUST provide adequate timing accuracy so that different CMs do not appreciably interfere with each other. S-CDMA utilizes precise synchronization so that multiple CMs can transmit simultaneously.
+
+The upstream modulator is part of the cable modem which interfaces with the cable network. The modulator contains the electrical-level modulation function and the digital signal-processing function; the latter provides the FEC, preamble prepend, symbol mapping, and other processing steps.
+
+At the demodulator, similar to the modulator, there are two basic functional components: the demodulation function and the signal processing function. The demodulator resides in the CMTS
+
+and there is one demodulation function (not necessarily an actual physical demodulator) for each carrier frequency in use. The demodulation function receives all bursts on a given frequency.
+
+The demodulation function of the demodulator accepts a varying-level signal centred around a commanded power level and performs symbol timing and carrier recovery and tracking, burst acquisition, and demodulation. Additionally, the demodulation function provides an estimate of burst timing relative to a reference edge, an estimate of received signal power, may provide an estimate of signal-to-noise ratio, and may engage adaptive equalization to mitigate the effects of:
+
+- a) echoes in the cable plant;
+- b) narrow-band ingress; and
+- c) group delay.
+
+The signal-processing function of the demodulator performs the inverse processing of the signal-processing function of the modulator. This includes accepting the demodulated burst data stream and decoding, etc. The signal-processing function also provides the edge-timing reference and gating-enable signal to the demodulators to activate the burst acquisition for each assigned burst slot. The signal-processing function may also provide an indication of successful decoding, decoding error, or fail-to-decode for each codeword and the number of corrected Reed-Solomon symbols in each codeword. For every upstream burst, the CMTS has a prior knowledge of the exact burst length in modulation intervals (see clauses 6.2.5.1, 6.2.19 and A.2).
+
+### 6.2.2 Signal processing requirements
+
+The signal processing order for each burst packet type MUST be compatible with the sequence shown in Figure 6-1. For TDMA mode, the signal processing order for each burst packet type MUST follow the order of steps in Figure 6-2. For S-CDMA mode, the signal processing order for each burst packet type MUST follow the order of steps in Figure 6-3.
+
+![Figure 6-1: Upstream signal-processing sequence diagram. The sequence starts with 'Burst data in' entering an 'R-S encoder'. The output of the R-S encoder goes to a 'Byte interleaver (TDMA only)'. The output of the Byte interleaver goes to a 'Scrambler'. The output of the Scrambler goes to a 'TCM encoder (S-CDMA only)'. The output of the TCM encoder is summed with a 'Preamble prepend' at a summation node (indicated by a circle with a plus sign). The output of the summation node goes to a 'Framer (S-CDMA only)'. The output of the Framer goes to a 'Symbol mapper'. The output of the Symbol mapper goes to a 'Spreader (S-CDMA only)'. The output of the Spreader goes to a 'Transmit equalizer'. The output of the Transmit equalizer goes to a 'Filter'. The output of the Filter goes to a 'Modulator'. The output of the Modulator is 'RF out'. A feedback loop connects the output of the Modulator back to the input of the R-S encoder. The diagram is labeled 'J.122_F6-1' in the bottom right corner.](8c880d6b715587bd710a9ba8414469b1_img.jpg)
+
+```
+graph LR; A[Burst data in] --> B[R-S encoder]; B --> C[Byte interleaver (TDMA only)]; C --> D[Scrambler]; D --> E[TCM encoder (S-CDMA only)]; E --> F((+)); G[Preamble prepend] --> F; F --> H[Framer (S-CDMA only)]; H --> I[Symbol mapper]; I --> J[Spreader (S-CDMA only)]; J --> K[Transmit equalizer]; K --> L[Filter]; L --> M[Modulator]; M --> N[RF out]; M --> A;
+```
+
+Figure 6-1: Upstream signal-processing sequence diagram. The sequence starts with 'Burst data in' entering an 'R-S encoder'. The output of the R-S encoder goes to a 'Byte interleaver (TDMA only)'. The output of the Byte interleaver goes to a 'Scrambler'. The output of the Scrambler goes to a 'TCM encoder (S-CDMA only)'. The output of the TCM encoder is summed with a 'Preamble prepend' at a summation node (indicated by a circle with a plus sign). The output of the summation node goes to a 'Framer (S-CDMA only)'. The output of the Framer goes to a 'Symbol mapper'. The output of the Symbol mapper goes to a 'Spreader (S-CDMA only)'. The output of the Spreader goes to a 'Transmit equalizer'. The output of the Transmit equalizer goes to a 'Filter'. The output of the Filter goes to a 'Modulator'. The output of the Modulator is 'RF out'. A feedback loop connects the output of the Modulator back to the input of the R-S encoder. The diagram is labeled 'J.122\_F6-1' in the bottom right corner.
+
+Figure 6-1 – Upstream signal-processing sequence
+
+![](0b7849dae424b0dd33e6386d2384643a_img.jpg)
+
+|                          |                                                                                                                                 |
+|--------------------------|---------------------------------------------------------------------------------------------------------------------------------|
+|                          | Packet stream input                                                                                                             |
+|                          | ↓                                                                                                                               |
+| <b>Block the data</b>    | Separate packet into information blocks (= data bytes in one codeword)                                                          |
+|                          | ↓                                                                                                                               |
+| <b>R-S encode</b>        | R-S (Reed-Solomon) encode each information block, using shortened codeword for last block if needed. R-S FEC can be turned off. |
+|                          | ↓                                                                                                                               |
+| <b>Byte interleave</b>   | R-S Byte interleave. R-S Byte interleaver can be turned off.                                                                    |
+|                          | ↓                                                                                                                               |
+| <b>Scramble</b>          | Scramble (see Figure 6-7)                                                                                                       |
+|                          | ↓                                                                                                                               |
+| <b>Preamble prepend</b>  | Prepend preamble symbols                                                                                                        |
+|                          | ↓                                                                                                                               |
+| <b>Symbol map</b>        | Map the data stream into modulator symbols                                                                                      |
+|                          | ↓                                                                                                                               |
+| <b>Transmit equalize</b> | Pre-equalize the symbol stream                                                                                                  |
+|                          | ↓                                                                                                                               |
+| <b>Filter</b>            | Filter symbol stream for spectral shaping                                                                                       |
+|                          | ↓                                                                                                                               |
+| <b>Modulate</b>          | Modulate at precise times (QPSK; 8QAM; 16QAM; 32QAM; 64QAM)                                                                     |
+|                          | ↓                                                                                                                               |
+|                          | Output RF waveform burst                                                                                                        |
+
+**Figure 6-2 – TDMA upstream transmission processing**
+
+![](798679874d1c29f8343506a156c79d7e_img.jpg)
+
+|                          |                                                                                                                                 |
+|--------------------------|---------------------------------------------------------------------------------------------------------------------------------|
+|                          | Packet stream input                                                                                                             |
+|                          | ↓                                                                                                                               |
+| <b>Block the data</b>    | Separate packet into information blocks (= data bytes in one codeword)                                                          |
+|                          | ↓                                                                                                                               |
+| <b>R-S encode</b>        | R-S (Reed-Solomon) encode each information block, using shortened codeword for last block if needed. R-S FEC can be turned off. |
+|                          | ↓                                                                                                                               |
+| <b>Scramble</b>          | Scramble (see Figure 6-7)                                                                                                       |
+|                          | ↓                                                                                                                               |
+| <b>TCM encode</b>        | TCM (trellis-coded modulation) encode the bytes. TCM can be turned off.                                                         |
+|                          | ↓                                                                                                                               |
+| <b>Preamble prepend</b>  | Prepend preamble symbols                                                                                                        |
+|                          | ↓                                                                                                                               |
+| <b>S-CDMA framer</b>     | Frame and interleave the data into mini-slots                                                                                   |
+|                          | ↓                                                                                                                               |
+| <b>Symbol map</b>        | Map the data stream into modulator symbols                                                                                      |
+|                          | ↓                                                                                                                               |
+| <b>S-CDMA spreader</b>   | Spread the symbols. For spreader-off on S-CDMA channels, spreader can be turned off.                                            |
+|                          | ↓                                                                                                                               |
+| <b>Transmit equalize</b> | Pre-equalize the symbol stream                                                                                                  |
+|                          | ↓                                                                                                                               |
+| <b>Filter</b>            | Filter symbol stream for spectral shaping                                                                                       |
+|                          | ↓                                                                                                                               |
+| <b>Modulate</b>          | Modulate at precise times (QPSK; 8QAM; 16QAM; 32QAM; 64QAM, 128QAM/TCM only)                                                    |
+|                          | ↓                                                                                                                               |
+|                          | Output RF waveform burst                                                                                                        |
+
+**Figure 6-3 – S-CDMA upstream transmission processing**
+
+The blocks used only in S-CDMA consist of a TCM encoder, S-CDMA framer, and S-CDMA spreader. The TCM encoder provides trellis modulation encoding of data symbols and is described in clause 6.2.8. The S-CDMA framer maps mini-slots into code resources and provides interleaving of data symbols and is described in clause 6.2.11. The S-CDMA spreader spreads S-CDMA framed symbols for transmission and is described in clause 6.2.14.
+
+### 6.2.3 Modulation formats
+
+The modulation formats listed here specify requirements for J.122-compliant equipment. Cable operators are free to configure the modulation format to best address their system characteristics and application requirements.
+
+The upstream modulator MUST provide QPSK and 16QAM differential encoded modulations for TDMA.
+
+The upstream modulator MUST provide QPSK, 8QAM, 16QAM, 32QAM, and 64QAM modulations for TDMA and S-CDMA channels.
+
+The upstream modulator MUST provide QPSK, 8QAM, 16QAM, 32QAM, 64QAM and 128QAM TCM encoded modulations for S-CDMA channels.
+
+The upstream demodulator MAY support QPSK and 16QAM differential modulation for TDMA.
+
+The upstream demodulator MUST support QPSK, 16QAM, and 64QAM modulations for TDMA and S-CDMA channels.
+
+The upstream demodulator MAY support 8QAM and 32QAM modulation for TDMA and S-CDMA channels.
+
+The upstream demodulator MAY support QPSK, 8QAM, 16QAM, 32QAM, 64QAM, and 128QAM TCM encoded modulations for S-CDMA channels.
+
+### 6.2.4 R-S encode
+
+#### 6.2.4.1 R-S encode modes
+
+The upstream modulator MUST be able to provide the following selections: Reed-Solomon codes over GF(256) with  $T = 1$  to 16 or no R-S coding.
+
+The following Reed-Solomon generator polynomial MUST be supported:
+
+$$g(x) = (x + \alpha^0)(x + \alpha^1) \dots (x + \alpha^{2T-1})$$
+
+where the primitive element alpha is 0x02 hex.
+
+The following Reed-Solomon primitive polynomial MUST be supported:
+
+$$p(x) = x^8 + x^4 + x^3 + x^2 + 1$$
+
+The upstream modulator MUST provide codewords from a minimum size of 18 bytes (16 information bytes [ $k$ ] plus two parity bytes for  $T = 1$  error correction) to a maximum size of 255 bytes ( $k$ -bytes plus parity-bytes). The minimum uncoded word size MUST be one byte.
+
+In shortened last codeword mode, the CM MUST provide the last codeword of a burst shortened from the assigned length of  $k$  data bytes per codeword as described in clause 6.2.5.1.3.
+
+The value of  $T$  MUST be configured in response to the upstream channel descriptor from the CMTS.
+
+#### 6.2.4.2 R-S bit-to-symbol ordering
+
+The input to the Reed-Solomon encoder is logically a serial bit stream from the MAC layer of the CM, and the first bit of the stream MUST be mapped into the MSB of the first Reed-Solomon symbol into the encoder. The MSB of the first symbol out of the encoder MUST be mapped into the first bit of the serial bit stream fed to the scrambler.
+
+NOTE – The MAC byte-to-serial upstream convention calls for the byte LSB to be mapped into the first bit of the serial bit stream per clause 8.2.1.3.
+
+### 6.2.5 R-S frame structure
+
+Figure 6-4 shows two examples of the R-S frame structure: one where the packet length equals the number of information bytes in a codeword, and another where the packet length is longer than the number of information bytes in one codeword, but less than in two codewords. Example 1 illustrates the fixed codeword-length mode, and example 2 illustrates the shortened last codeword mode. These modes are defined in clause 6.2.5.1.
+
+Example 1) Packet length = number of information bytes in codeword =  $k$
+
+![Diagram for Example 1 showing a single codeword structure. It consists of five blocks: Preamble, Packet data, FEC parity, Guard time, and Empty up to next mini-slot boundary. A double-headed arrow labeled 'One codeword' spans over the Packet data and FEC parity blocks.](878d9539700bd792e7d12ad6f1203c5d_img.jpg)
+
+|          |              |            |            |                                     |
+|----------|--------------|------------|------------|-------------------------------------|
+| Preamble | One codeword |            | Guard time | Empty up to next mini-slot boundary |
+|          | Packet data  | FEC parity |            |                                     |
+
+Diagram for Example 1 showing a single codeword structure. It consists of five blocks: Preamble, Packet data, FEC parity, Guard time, and Empty up to next mini-slot boundary. A double-headed arrow labeled 'One codeword' spans over the Packet data and FEC parity blocks.
+
+Example 2) Packet length =  $k + \text{remaining information bytes in 2nd codeword} = k + k' \leq k + k'' \leq 2k$
+
+![Diagram for Example 2 showing a two-codeword structure. The top part shows Preamble, Two codewords, and Guard time, with a 'Mini-slot boundary' indicated after the Guard time. The bottom part details the 'Two codewords' section, showing: First k bytes of packet, FEC parity, Last k' bytes of packet, k'' - k' bytes of zero-fill, and FEC parity. Dashed lines connect the 'Two codewords' block to its detailed view.](8e80de0cac529b2c3775d677c5203133_img.jpg)
+
+|                           |               |                           |                               |            |
+|---------------------------|---------------|---------------------------|-------------------------------|------------|
+| Preamble                  | Two codewords |                           |                               | Guard time |
+| First $k$ bytes of packet | FEC parity    | Last $k'$ bytes of packet | $k'' - k'$ bytes of zero-fill | FEC parity |
+
+Diagram for Example 2 showing a two-codeword structure. The top part shows Preamble, Two codewords, and Guard time, with a 'Mini-slot boundary' indicated after the Guard time. The bottom part details the 'Two codewords' section, showing: First k bytes of packet, FEC parity, Last k' bytes of packet, k'' - k' bytes of zero-fill, and FEC parity. Dashed lines connect the 'Two codewords' block to its detailed view.
+
+J.122\_F6-4
+
+**Figure 6-4 – Example frame structures with flexible burst length mode**
+
+#### 6.2.5.1 R-S codeword length
+
+When R-S FEC is enabled, the CM operates in either fixed-length codeword mode or in shortened last codeword mode. The minimum number of information bytes in a codeword in either mode is 16. Shortened last codeword mode only provides a benefit when the number of bytes in a codeword is greater than the minimum of 16 bytes.
+
+The intent of the following clauses is to define rules and conventions such that CMs request the proper number of mini-slots and the CMTS PHY knows what to expect regarding the R-S FEC framing in both fixed codeword length and shortened last codeword modes. Shortened last codeword mode MUST NOT be used for initial maintenance (broadcast or unicast).
+
+##### 6.2.5.1.1 Burst size
+
+For an allocation of mini-slots (in both contention and non-contention regions), the requirements of clauses 6.2.5.1.2 and 6.2.5.1.3 apply to a burst transmitted in that allocation. Regardless of the size of the allocation, the size of the burst MUST be as specified in Table 6-1 below.
+
+**Table 6-1 – Burst size**
+
+| IUC       | Burst size                                                                                                                                                                                          |
+|-----------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 1, 3      | Minimum number of mini-slots required for message transmission including burst overhead. Burst overhead includes preamble, R-S parity bytes, TCM return-to-zero bits, and guard time if applicable. |
+| 2         | Number of mini-slots specified in the well-known multicast SID (refer to Annex A).                                                                                                                  |
+| 4-6, 9-11 | Number of mini-slots allocated.                                                                                                                                                                     |
+
+##### 6.2.5.1.2 Fixed codeword length
+
+With the fixed-length codewords, after all the data are encoded, zero-fill will occur in this codeword if necessary to reach the assigned  $k$  data bytes per codeword. Additionally, zero-fill MUST continue
+
+up to the point when no additional fixed-length codewords can be inserted before the end of the burst specified in Table 6-1 above, accounting for preamble, FEC parity, return-to-zero bits and guard-time symbols (if any).
+
+##### 6.2.5.1.3 Shortened last codeword
+
+As shown in Figure 6-4, let  $k'$  = the number of information bytes that remain after partitioning the information bytes of the burst into full-length ( $k$  burst data bytes) codewords. The value of  $k'$  is less than  $k$ . Given operation in a shortened last codeword mode, let  $k''$  = the number of burst data bytes plus zero-fill bytes in the shortened last codeword. In shortened codeword mode, the CM MUST encode the data bytes of the burst (including MAC header) using the assigned codeword size ( $k$  information bytes per codeword) until 1) all the data are encoded, or 2) a remainder of data bytes is left over which is less than  $k$ . Shortened last codewords MUST NOT have less than 16 information bytes, and this is to be considered when CMs make requests of mini-slots. In shortened last codeword mode, the CM MUST zero-fill data if necessary up to the burst size specified in Table 6-1 above, accounting for preamble, FEC parity, return-to-zero bits, and guard-time symbols (if any). Therefore, in many cases, only  $k'' - k'$  zero-fill bytes are necessary with  $16 \leq k'' \leq k$  and  $k' \leq k''$ .
+
+More generally, the CM MUST zero-fill data until the point when no additional fixed-length codewords can be inserted before the end of the burst specified in Table 6-1 above, accounting for preamble, FEC parity, return-to-zero bits, and guard-time symbols (if any), and then, if possible, a shortened last codeword of zero-fill MUST be inserted to fit into the last mini-slot.
+
+If, after zero-fill of additional codewords with  $k$  information bytes, there are less than 16 bytes remaining before the end of the burst specified in Table 6-1 above, accounting for preamble, FEC parity, return-to-zero bits, and guard-time symbols (if any), then the CM shall not create this last shortened codeword.
+
+#### 6.2.5.2 R-S FEC disabled
+
+When  $T = 0$  (no FEC parity bytes), the R-S encoder SHOULD zero-fill in full bytes to the end of the burst specified in clause 6.2.5.1.1 above, accounting for preamble, return-to-zero bits, and guard-time symbols (if any).
+
+### 6.2.6 TDMA byte interleaver
+
+R-S codeword interleaving in a byte (R-S symbol) format MUST be performed after R-S encoding on a TDMA channel. The byte interleaver changes the order of the bytes at the R-S encoder output, i.e., it performs an operation of byte permutation. At the receiver side, the original order of bytes is restored prior to the R-S decoding. Therefore, if some consecutive bytes were corrupted by burst noise, they are spread between various R-S codewords, averaging the number of erroneous bytes in each codeword. The interleaver is a block interleaver type, i.e., the permutation is achieved by filling a table row-wise (one row per R-S codeword), and reading it column-wise. The total memory size allocated for the table is 2048 bytes.
+
+The byte interleaver is disabled when the R-S encoder is turned off ( $T = 0$ ).
+
+#### 6.2.6.1 Byte interleaver parameters
+
+The interleaver operating parameters described in Table 6-2 determine the operation of the interleaver for every burst.
+
+**Table 6-2 – Interleaver operating parameters**
+
+| Parameter | Definition                                                 | Allowed Values                                                                    |
+|-----------|------------------------------------------------------------|-----------------------------------------------------------------------------------|
+| $N_r$     | Interleaver width (R-S codeword length, $k + 2 \times T$ ) | 18 to 255                                                                         |
+| $I_r$     | Interleaver depth                                          | 0: Dynamic mode<br>1: No interleaving<br>2 to floor ( $2048/N_r$ ) for fixed mode |
+| $B_r$     | Interleaver block size                                     | $2 \times N_r$ to 2048                                                            |
+| $N_f$     | Packet size (in bytes, including FEC)                      | $\geq 18$ bytes                                                                   |
+
+The CMTS and CM MUST use the interleaver parameters within the allowed values in Table 6-2 with the following additional restrictions:
+
+- 1)  $N_r$  and  $I_r$  MUST be chosen such that  $N_r \times I_r \leq 2048$  (in other words, for a given  $N_r$ , the maximal value of  $I_r$  is  $I_{r,max} = \text{floor}(2048/N_r)$ ).
+- 2)  $N_r$  MUST be identical to the R-S codeword length (i.e.,  $k + 2T$ ).
+- 3)  $B_r$  is effective only when  $I_r = 0$ . This mode is called dynamic mode.
+- 4) When  $I_r = 1$ , interleaving is disabled.
+
+$N_r$ ,  $I_r$  and  $B_r$  are specified in the burst profile, and  $N_f$  is implied in the MAP message.
+
+#### 6.2.6.2 Interleaver operating modes
+
+The interleaver MUST support both an operating mode in which the block size is fixed, as well as a dynamic mode in which the interleaver depth is determined based on the burst size.
+
+##### 6.2.6.2.1 Fixed mode
+
+The R-S encoded data bytes of the packet are first divided into interleaver blocks of  $N_r \times I_r$  bytes (i.e., blocks of  $I_r$  R-S codewords each). The size of the last interleaver block may be smaller when the packet length is not an integer multiple of  $N_r \times I_r$ . Each interleaver block is interleaved separately.
+
+Each interleaver block is filled into a table with  $I_r$  rows and  $N_r$  columns. The data is written row by row (from left to right). Therefore, each row corresponds to one R-S codeword. The bytes are read column by column (from top to bottom). The interleaver operation is demonstrated in Figure 6-5.
+
+![](d116934392360da963e91d840d1e45a8_img.jpg)
+
+Write →
+
+|              |              |  |                |
+|--------------|--------------|--|----------------|
+| $C_1(1)$     | $C_1(2)$     |  | $C_1(N_r)$     |
+| $C_2(1)$     | $C_2(2)$     |  | $C_2(N_r)$     |
+|              |              |  |                |
+| $C_{I_r}(1)$ | $C_{I_r}(2)$ |  | $C_{I_r}(N_r)$ |
+
+↓ Read
+
+Input sequence:  $C_1(1), \dots, C_1(N_r), C_2(1), \dots, C_2(N_r), C_3(1), \dots, C_{I_r}(N_r)$
+
+Output sequence:  $C_1(1), C_2(1), \dots, C_{I_r}(1), C_1(2), \dots, C_{I_r}(2), C_1(3), \dots, C_{I_r}(N_r)$
+
+J.122\_F6-5
+
+**Figure 6-5 – Byte interleaver operation**
+
+The last interleaver block might have fewer rows than  $I_r$ . If the shortened last codeword mode is applied, then the last row might have fewer elements than  $N_r$ . In these cases, the interleaver table is read column by column, skipping the empty elements of the table. The interleaver operation for the last interleaver block is demonstrated in Figure 6-6.
+
+![](b9c0d46c1148cf65cb79f27fac420981_img.jpg)
+
+Write →
+
+|          |          |  |               |  |                |
+|----------|----------|--|---------------|--|----------------|
+| $C_1(1)$ | $C_1(2)$ |  | $C_1(N')$     |  | $C_1(N_r)$     |
+| $C_2(1)$ | $C_2(2)$ |  |               |  | $C_2(N_r)$     |
+|          |          |  |               |  |                |
+|          |          |  | $C_{r-1}(N')$ |  | $C_{r-1}(N_r)$ |
+| $C_r(1)$ | $C_r(2)$ |  | $C_r(N')$     |  |                |
+
+↓ Read
+
+Input sequence:  
+ $C_1(1), \dots, C_1(N_r), C_2(1), \dots, C_2(N_r), C_3(1), \dots, C_r(1), \dots, C_r(N')$
+
+Output sequence:  
+ $C_1(1), C_2(1), \dots, C_r(1), \dots, C_1(2), \dots, C_r(2), C_1(N'), \dots, C_r(N'), C_1(N'+1), \dots, C_{r-1}(N'+1), C_1(N'+2), \dots, C_{r-1}(N'+2), \dots, C_1(N_r), \dots, C_{r-1}(N_r)$
+
+J.122\_F6-6
+
+**Figure 6-6 – Interleaver operation for last interleaver block  
+(with shortened last codeword)**
+
+##### 6.2.6.2.2 Dynamic mode
+
+In the fixed mode, the interleaving depth of the last interleaving block of a packet ( $I'$  in Figure 6-6) may be as small as one, resulting in low burst noise robustness for this block. In the dynamic mode, the depths of the interleaver blocks are chosen such that all blocks have approximately the same depth to achieve nearly optimal burst noise robustness (for the given block size).
+
+The R-S encoded data bytes of the packet are first divided into  $N_s^0$  interleaver blocks. The size of the  $i$ -th interleaver block is  $N_r \times I_r^{(i)}$  bytes (i.e., a block of  $I_r^{(i)}$  R-S codewords). The size of the last interleaver block may be smaller in the shortened last codeword mode. Each interleaver block is interleaved separately (see the equations for  $N_s^0$  and  $I_r^{(i)}$  in clause 6.2.6.2.2.1).
+
+The  $i$ -th interleaver block is filled into a table with  $I_r^{(i)}$  rows and  $N_r$  columns. The data is written row-wise (from left to right). Therefore, each row corresponds to one R-S codeword. The bytes are read column-wise (from top to bottom). The interleaver operation is demonstrated in Figure 6-5 (except that there are  $I_r^{(i)}$  rows instead of  $I_r$ ).
+
+If the shortened last codeword mode is applied, then the last row might have fewer elements than  $N_r$ . In this case, the interleaver table is read column by column, skipping the empty elements of the table. The interleaver operation for the last interleaver block is demonstrated in Figure 6-6 (except that there are  $I_r(N_s^0)$  rows instead of  $I'$ ).
+
+###### 6.2.6.2.2.1 Dynamic mode calculations
+
+$N_s^0$  and  $I_r^{(i)}$  are determined by the following equations:
+
+Total number of interleaver rows:  $I_{tot}^0 = \text{ceil}(N_f / N_r)$
+
+Maximal number of rows per segment:  $I_{r,max} = \text{floor}(B_r / N_r)$
+
+Number of segments:  $N_s^0 = \text{ceil}(I_{tot}^0 / I_{r,max})$
+
+Interleaver depth of first block:  $I_r^1 = \text{floor}(I_{tot}^0 / N_s^0)$
+
+No. of blocks with depth of  $I_r^1$ :  $M = N_s^0 \cdot (I_r^1 + 1) - I_{tot}^0$
+
+Then for segment  $i$ ,  $I_r^{(i)}$  is calculated as follows ( $i=1 \dots N_s^0$ ):
+
+$$I_r^{(i)} = \begin{cases} I_r^1, & i=1, \dots, M \\ I_r^1 + 1, & i=M+1, \dots, N_s^0 \end{cases}$$
+
+### 6.2.7 Scrambler (randomizer)
+
+The upstream modulator MUST implement a scrambler (shown in Figure 6-7) where the 15-bit seed value MUST be arbitrarily programmable.
+
+![Figure 6-7 – Scrambler structure. The diagram shows a 15-bit shift register (N=15) with delay elements 1 through N. The register is initialized with a 15-bit seed value (Seed LSB to Seed MSB) via a 'Seedload/frame reset' input. The output of the last delay element (N) is fed into an XOR gate along with the 'Randomizer data input'. The output of this XOR gate is the 'Randomizer data output' and is also fed back into the first delay element (1) to continue the scrambling sequence.](a3b3abbf6d0b18f3dd4a83680b5e3e42_img.jpg)
+
+Figure 6-7 – Scrambler structure. The diagram shows a 15-bit shift register (N=15) with delay elements 1 through N. The register is initialized with a 15-bit seed value (Seed LSB to Seed MSB) via a 'Seedload/frame reset' input. The output of the last delay element (N) is fed into an XOR gate along with the 'Randomizer data input'. The output of this XOR gate is the 'Randomizer data output' and is also fed back into the first delay element (1) to continue the scrambling sequence.
+
+Figure 6-7 – Scrambler structure
+
+At the beginning of each burst, the register is cleared and the seed value is loaded. The seed value MUST be used to calculate the scrambler bit which is combined in an XOR with the first bit of data of each burst (which is the MSB of the first symbol following the last symbol of the preamble).
+
+The scrambler seed value MUST be configured in response to the upstream channel descriptor from the CMTS.
+
+The polynomial MUST be  $x^{15} + x^{14} + 1$ .
+
+### 6.2.8 TCM encoder
+
+R-S symbol interleaving is commonly included between the TCM and R-S blocks to preserve coding gain in the presence of bursty errors produced at the output of the TCM decoder. This interleaver was not included in the original baseline S-CDMA proposal to reduce memory requirements at the expense of coding gain.
+
+In S-CDMA mode the CM MUST support trellis-coded modulation for transmission of  $m = 1, 2, 3, 4, 5$  and 6 bits per symbol with QPSK0, 8QAM, 16QAM, 32QAM, 64QAM and 128QAM constellations, respectively. Support of TCM in the CMTS is optional.
+
+Figure 6-8 shows the employed 8-state TCM encoder. The encoding operation causes a mapping of  $m$  input bits into  $m + 1$  output bits for input into the symbol mapping block. The systematic convolutional encoder adds the coded bit  $x^1 = s^0$  to the input bits  $i^m, \dots, i^3, i^2, i^1$ . For  $m = 1$ , only input bit  $i^1$  is used ( $i^2 = 0$ ), and encoding is reduced to rate-1/2 coding.
+
+![Figure 6-8: Convolutional encoder diagram. The diagram shows a systematic convolutional encoder. On the left, input bits i^m, ..., i^3, i^2, i^1 are shown. The input i^1 is split: one path goes directly to the 'S-CDMA framing' block, and the other path goes through a series of three delay (D) blocks and two adders (circles with a cross). The first adder also receives a feedback signal from the output of the third delay block. The outputs of the delay blocks are labeled s^2, s^1, and s^0 = x^1. These state bits are also fed into the 'S-CDMA framing' block. The 'S-CDMA framing' block outputs 'Symbol labels'. A label 'J.122_F6-8' is at the bottom right of the diagram.](8f7c0bf0c75a31fee6b0c7392ff57c39_img.jpg)
+
+Figure 6-8: Convolutional encoder diagram. The diagram shows a systematic convolutional encoder. On the left, input bits i^m, ..., i^3, i^2, i^1 are shown. The input i^1 is split: one path goes directly to the 'S-CDMA framing' block, and the other path goes through a series of three delay (D) blocks and two adders (circles with a cross). The first adder also receives a feedback signal from the output of the third delay block. The outputs of the delay blocks are labeled s^2, s^1, and s^0 = x^1. These state bits are also fed into the 'S-CDMA framing' block. The 'S-CDMA framing' block outputs 'Symbol labels'. A label 'J.122\_F6-8' is at the bottom right of the diagram.
+
+**Figure 6-8 – Convolutional encoder**
+
+The initial state of the TCM encoder MUST be the zero state. The zero state MUST be reached again with the last encoded symbol.
+
+To return to the zero state from all possible trellis paths, if  $m = 1$  (QPSK) three tail symbols ( $n_t = 3$ ) MUST be generated with input bit  $i^1$  set to  $i^1 = s^1$ . By inspection of Figure 6-8, after three symbols, the state bits  $s^2, s^1$  and  $s^0 = x^1$  will be zero. Tail symbols are extra symbols, which carry no information.
+
+If  $m = 2$ , to return to the zero state from all possible trellis paths, two tail symbols ( $n_t = 2$ ) MUST be generated. The input bits  $i^2 i^1$  MUST be set such that the zero state is reached after two symbols. If the first symbol is set to  $i^2 = 0, i^1 = s^1$ , and the second (final) symbol to  $i^2 = s^2, i^1 = s^1$  after these two symbols the state bits  $s^2, s^1$ , and  $s^0 = x^1$  will be zero.
+
+If  $m \geq 3$ , the uncoded bits  $i^m, \dots, i^3$  MUST be used for information encoding, when this is possible. Otherwise, uncoded bits MUST be set to zero. The number of tail symbols carrying no information depends on the ending conditions and can vary between zero and two ( $0 \leq n_t \leq 2$ ).
+
+#### 6.2.8.1 Byte to TCM symbol mapping
+
+The mapping of R-S bytes to TCM symbols is done such that each byte is mapped entirely to the uncoded bits  $i^m, \dots, i^3$ , or entirely to the convolutional encoder input bits  $i^2 i^1$ . The decision is made sequentially for each byte using the rule that the byte assignment should lead to the shortest packet of symbols including tail symbols, if the current byte were the last byte to be encoded. This rule results in the repetitive patterns of byte assignments to label bits shown in Figure 6-9 for  $m = 1$  to 6. In the figure bit  $i^m$  is at the top and bit  $i^1$  is at the bottom.
+
+![Diagram showing repetitive patterns of byte mapping to symbol map bits for TCM for various modulation schemes: m=6 (128QAM), m=5 (64QAM), m=4 (32QAM), m=3 (16QAM), m=2 (8QAM), and m=1 (QPSK).](96b090628713287072839afc1b077881_img.jpg)
+
+The diagram illustrates the mapping of bytes (labeled 1, 2, 3, 4, 5) to symbol bits for different modulation orders.   
+- m=6 (128QAM): Shows bytes 1, 2, and 3 mapped across a grid of bits.  
+- m=5 (64QAM): Shows bytes 1, 2, 3, 4, and 5 mapped across a grid, with some bytes split across bit boundaries.  
+- m=4 (32QAM): Shows bytes 1 and 2 mapped.  
+- m=3 (16QAM): Shows bytes 1, 2, and 3 mapped.  
+- m=2 (8QAM): Shows bytes 1 and 2 mapped.  
+- m=1 (QPSK): Shows an empty grid for bit mapping.  
+Each row represents a different modulation level, and the horizontal axis represents bit positions within symbols.
+
+J.122\_F6-9
+
+Diagram showing repetitive patterns of byte mapping to symbol map bits for TCM for various modulation schemes: m=6 (128QAM), m=5 (64QAM), m=4 (32QAM), m=3 (16QAM), m=2 (8QAM), and m=1 (QPSK).
+
+**Figure 6-9 – Repetitive patterns of byte mapping to symbol map bits for TCM**
+
+The MSB ( $i^m$ ) MUST be the first bit in the serial data fed into the uncoded input bits (i.e.,  $i^m$  to  $i^3$ ). The MSB ( $i^2$ ) MUST be the first bit in the serial data fed into the coded input bits.
+
+Figure 6-10 illustrates the byte assignments for Trellis-coded 64QAM modulation by two examples. Notice that bytes are assigned in a repetitive pattern of five bytes. In the first example,  $N_f$  is divisible by five. In this case two tail symbols are appended. In the second example,  $N_f$  is not divisible by five and no tail symbols are required. The bits needed for returning to the zero state are available in symbols still carrying information.
+
+![Figure 6-10: Example byte to bit assignment for 64QAM. The diagram consists of two horizontal layouts of bit grids. The top layout shows a sequence starting with 'Zero initial state' leading into 'np preamble symbols', followed by 'ni TCM symbols', and ending with 'nt = 2 tail symbols' which reach a 'Zero final state'. Specific bits are labeled as msb 1, 2, 3, 6, 8, Ni-2, and Ni. On the right, bit rows are indexed x^1 to x^6. The bottom layout shows 'ni TCM symbols, no tail symbols (nt = 0)'. A legend identifies three patterns: checkered for 'Zero fill bits', diagonal stripes for 'Bits to return to zero state', and vertical bars for 'Redundant code bits'.](2580688a4de0a29692805cc6ba4822d7_img.jpg)
+
+Zero initial state
+
+Zero final state
+
+msb 1
+
+msb 2
+
+msb 3
+
+msb 6
+
+msb 8
+
+msb  $N_i-2$
+
+msb  $N_i-1$
+
+msb  $N_i$
+
+$n_p$  preamble symbols
+
+$n_i$  TCM symbols
+
+$n_t = 2$  tail symbols
+
+$n_i$  TCM symbols, no tail symbols ( $n_t = 0$ )
+
+Zero fill bits
+
+Bits to return to zero state
+
+Redundant code bits
+
+$x^6$   
+ $x^5$   
+ $x^4$   
+ $x^3$   
+ $x^2$   
+ $x^1$
+
+J.122\_F6-10
+
+Figure 6-10: Example byte to bit assignment for 64QAM. The diagram consists of two horizontal layouts of bit grids. The top layout shows a sequence starting with 'Zero initial state' leading into 'np preamble symbols', followed by 'ni TCM symbols', and ending with 'nt = 2 tail symbols' which reach a 'Zero final state'. Specific bits are labeled as msb 1, 2, 3, 6, 8, Ni-2, and Ni. On the right, bit rows are indexed x^1 to x^6. The bottom layout shows 'ni TCM symbols, no tail symbols (nt = 0)'. A legend identifies three patterns: checkered for 'Zero fill bits', diagonal stripes for 'Bits to return to zero state', and vertical bars for 'Redundant code bits'.
+
+**Figure 6-10 – Example byte to bit assignment for 64QAM**
+
+The CM MUST place the return-to-zero bits right after the last coded data sub-symbol, that is, the last coded sub-symbol corresponding to the parity bytes of the last shortened or fixed codeword including any zero-filled codeword in the grant. The rest of the coded bits MUST be filled with zeros.
+
+Figure 6-11 illustrates the placing of return-to-zero bits for 64QAM when the last transmitted byte is #1. The first two pairs of  $x^2$  and  $x^3$  are the return-to-zero bits, and the last empty coded pair is zero filled.
+
+![Diagram showing a 6x3 grid of bits with a legend. The grid shows a sequence of bits over time (rows 1 to 6). Row 1: u, u, u; Row 2: u, u, u; Row 3: u, u, 0; Row 4: 0, r, 0; Row 5: r, r, 0; Row 6: empty, empty, empty. Legend: 'u' for Uncoded bits, '0' for Zero fill bits, 'r' for Bits to return to zero state. Label J.122_F6-11.](4162c218fc7881cd90fc9574e07d2327_img.jpg)
+
+|                                |   |   |   |                   |
+|--------------------------------|---|---|---|-------------------|
+| <sup>5</sup><br>i <sup>1</sup> | u | u | u | <sup>6</sup><br>x |
+| <sup>4</sup><br>i <sup>1</sup> | u | u | u | <sup>5</sup><br>x |
+| <sup>3</sup><br>i <sup>1</sup> | u | u | 0 | <sup>4</sup><br>x |
+| <sup>2</sup><br>i <sup>1</sup> | 0 | r | 0 | <sup>3</sup><br>x |
+| <sup>1</sup><br>i <sup>1</sup> | r | r | 0 | <sup>2</sup><br>x |
+|                                |   |   |   | <sup>1</sup><br>x |
+
+u Uncoded bits  
+0 Zero fill bits  
+r Bits to return to zero state
+
+J.122\_F6-11
+
+Diagram showing a 6x3 grid of bits with a legend. The grid shows a sequence of bits over time (rows 1 to 6). Row 1: u, u, u; Row 2: u, u, u; Row 3: u, u, 0; Row 4: 0, r, 0; Row 5: r, r, 0; Row 6: empty, empty, empty. Legend: 'u' for Uncoded bits, '0' for Zero fill bits, 'r' for Bits to return to zero state. Label J.122\_F6-11.
+
+**Figure 6-11 – Example of return-to-zero bits followed by "0"**
+
+### 6.2.9 Preamble prepend
+
+The upstream PMD sublayer MUST support a variable-length preamble field that is prepended to the data after they have been randomized, Reed-Solomon encoded, and TCM encoded.
+
+The first bit of the preamble pattern is the first bit into the symbol mapper (see clause 6.2.13). The first bit of the preamble pattern is designated by the preamble value offset as described in Table 8-19. The preamble is interleaved by the framer in S-CDMA mode.
+
+The preamble sequence MUST be programmable. For DOCS 2.0 bursts (bursts encoded using a type 5 burst descriptor per clause 8.3.3), the preamble MUST use the QPSK0 or QPSK1 constellation (per Figures 6-18 and 6-19) with preamble length 0, 2, 4, 6, ..., or 1536 bits (maximum 768 QPSK symbols). For DOCS 1.x compatible bursts (type 4 burst descriptor) that use QPSK modulation, the preamble and data MUST use the QPSK0 constellation with preamble length 0, 2, 4, 6, ..., or 1024 bits (maximum 512 QPSK symbols). For DOCS 1.x compatible bursts (type 4 burst descriptor) that use 16QAM modulation, the preamble and data MUST use the 16QAM constellation with preamble length 0, 4, 8, 12, ..., or 1024 bits (maximum 256 16QAM symbols).
+
+The preamble length and value MUST be configured in response to the upstream channel descriptor message transmitted by the CMTS.
+
+### 6.2.10 Modulation rates
+
+In TDMA mode, the CM upstream modulator MUST provide all modulations at 160, 320, 640, 1280, 2560 and 5120 ksymb/s.
+
+In S-CDMA mode, the CM upstream modulator MUST provide all modulations at 1280, 2560 and 5120 ksymb/s.
+
+In TDMA mode, the CMTS upstream demodulator MUST be able to support demodulation at 160, 320, 640, 1280, 2560 and 5120 ksymb/s. In S-CDMA mode, the CMTS upstream demodulator MUST be able to support demodulation at 1280, 2560 and 5120 ksymb/s.
+
+This variety of modulation rates, and flexibility in setting upstream carrier frequencies, permits operators to position carriers in gaps in the pattern of narrow-band ingress, as discussed in Annex G.
+
+The modulation rate for each upstream channel is defined in an upstream channel descriptor (UCD) MAC message. All CMs using that upstream channel MUST use the defined modulation rate for upstream transmissions.
+
+### 6.2.11 S-CDMA framer and interleaver
+
+#### 6.2.11.1 S-CDMA framing considerations
+
+The S-CDMA mode of the PHY layer accepts data presented to it for transmission from the MAC layer. This data is presented as bursts of *n* mini-slots. These bursts are mapped within the PHY layer to a combination of spreading codes and time slots, in order to exploit the multi-dimensional spreading of information by the S-CDMA mode.
+
+There are various adjustable parameters in the upstream channel parameters and upstream burst attributes that allow controlling the mini-slot to physical layer mapping, as well as tuning the channel to accommodate a variety of channel conditions, noise characteristics, capacities, reliability levels, and latency requirements.
+
+When operating in S-CDMA mode, data is transmitted in two dimensions: codes and time. For this reason, data to be transmitted must be grouped into two-dimensional rectangular frames prior to transmission.
+
+At the physical layer, data is sent over an array of up to 128 spreading codes. There is a programmable number of *spreading intervals* per frame, as shown in Figure 6-13. A *spreading interval* is the time required to transmit one symbol per code across all 128 codes in S-CDMA mode. Note that the specific codes which are used and the details of the spreading operation are described in detail in clause 6.2.14, "S-CDMA spreader".
+
+A burst from a particular CM may be transmitted on two or more codes in one or more frames. A frame may contain bursts transmitted simultaneously from multiple CMs (each on a separate subset of the codes) as defined by the MAP message.
+
+#### 6.2.11.2 Mini-slot numbering
+
+In normal operation, the MAC will request the PHY to transmit a burst of length *n* mini-slots, starting at mini-slot *m*, as defined by the MAP. All CMs and the CMTS MUST have a common protocol of how mini-slots are numbered, and how they are mapped onto the physical layer framing structure. This common protocol is obtained from information in the SYNC and upstream channel descriptor (UCD) messages: (these messages are described in clauses 8.3.2 and 8.3.3).
+
+Mini-slots are mapped onto frames starting at the first active code (usually code number 0), are numbered sequentially through the remainder of the frame (code number 127), and then wrap to the next sequential frame. Mini-slots are mapped onto a group of consecutive codes.
+
+The CMTS and the CMs require a common protocol for mini-slot numbering. For operation on a TDMA channel, this is achieved solely through recovery of the timestamp. Since the time duration of an S-CDMA frame is not necessarily a power-of-2 multiple of the 10.24-MHz reference, the timestamp rollover (at  $2^{32}$  counts) is not necessarily at an S-CDMA frame boundary. Therefore, an additional synchronization step is required.
+
+The CMTS MUST identify frame boundaries relative to the timestamp counter on a periodic basis. This is called the *timestamp snapshot* and must be sent in the UCD for each upstream S-CDMA channel.
+
+The CMTS MUST maintain a frame counter and a mini-slot counter, and MUST sample these values along with the timestamp, on a frame boundary, as shown in Figure 6-12. The CMTS MUST obtain a new sample prior to sending each UCD message.
+
+![Figure 6-12 – Timestamp snapshot. The diagram illustrates the mapping of mini-slots to codes over time. At the top, three columns represent 'K spreading intervals'. Codes 127 and 126 have mini-slots m+62, m+125, and m+188. Codes 3, 2, and 1 have mini-slots m, m+63, and m+126. Codes 1 and 0 are shaded. Below this, a timeline shows 'Frame f', 'Frame f+1' (circled), and 'Frame f+2'. 'Timestamp counts' t1, t2, t3 (circled), and t4 are shown. Arrows point from t3 to a 'Timestamp snapshot' box containing 'Timestamp count' (32 bits), 'Mini-slot number' (32 bits), and 'Frame number' (8 bits). This snapshot is 'Included in UCD'. A label 'J.122_F6-12' is in the bottom right.](89f8aefc01866631793087542316cef2_img.jpg)
+
+Figure 6-12 – Timestamp snapshot. The diagram illustrates the mapping of mini-slots to codes over time. At the top, three columns represent 'K spreading intervals'. Codes 127 and 126 have mini-slots m+62, m+125, and m+188. Codes 3, 2, and 1 have mini-slots m, m+63, and m+126. Codes 1 and 0 are shaded. Below this, a timeline shows 'Frame f', 'Frame f+1' (circled), and 'Frame f+2'. 'Timestamp counts' t1, t2, t3 (circled), and t4 are shown. Arrows point from t3 to a 'Timestamp snapshot' box containing 'Timestamp count' (32 bits), 'Mini-slot number' (32 bits), and 'Frame number' (8 bits). This snapshot is 'Included in UCD'. A label 'J.122\_F6-12' is in the bottom right.
+
+**Figure 6-12 – Timestamp snapshot**
+
+Each CM MUST maintain a timestamp counter, mini-slot counter and frame counter functionally identical to the CMTS.
+
+From the UCD message, the CM receives the CMTS timestamp snapshot and parameters from which it can calculate the number of time counts per S-CDMA frame. Using modulo arithmetic, the CM can then calculate accurate values for timestamp, mini-slot and frame counters at any point into the future.
+
+The CM can then update its local mini-slot and frame counters at an appropriate timestamp counter value. At this point, the CM representation of mini-slots and frames are aligned with those in the CMTS.
+
+The CMTS and CM MUST implement a 32-bit timestamp counter, a 32-bit mini-slot counter, and an 8-bit frame counter, as follows:
+
+- The mini-slot counter MUST contain the value of the first mini-slot of the frame when it is sampled. It MAY be incremented by the number of mini-slots per frame, once per frame interval. The mini-slot counter will use all 32 bits and mini-slot numbers will therefore range from 0 to  $2^{32}-1$ .
+- The only specified function for the frame counter is to reset the code-hopping sequence at the frame 0 (modulo 256) boundary, as defined in clause 6.2.14.1.
+
+The frame structure above relates to the entire upstream and not necessarily to the transmission from a single CM. The codes are resources which are allocated to CMs over each S-CDMA frame. The assignment of codes to CMs is performed by the framer as it assigns a burst of symbols a
+
+particular order in the two-dimensional matrix of codes and time. This symbol sequencing is described in detail in clause 6.2.12.
+
+##### 6.2.11.2.1 Mini-slot numbering parameters in UCD
+
+There are three parameters specified in the UCD that define mini-slot mapping: *spreading intervals per frame*, *codes per mini-slot* and *number of active codes*.
+
+**Spreading intervals per frame:** The number of spreading intervals per frame,  $K$ , (along with the signalling rate),  $1/T_s$ , define the time duration of an S-CDMA frame,  $T_{fr}$ .
+
+$$T_{fr} = K \times 128 \times T_s$$
+
+Note that the code length in the above equation is always 128, regardless of how many codes are currently active.
+
+The valid range of the *spreading intervals per frame* parameter is 1 to 32.
+
+**Codes per mini-slot:** In conjunction with the spreading intervals per frame parameter, the codes per mini-slot ( $C_{ms}$ ) parameter defines the total number of symbols per mini-slot and therefore the mini-slot capacity. The mini-slot capacity,  $S_{ms}$ , is given in symbols by the following expression:
+
+$$S_{ms} = K \times C_{ms}$$
+
+The lower limit on mini-slot capacity is 16 symbols (refer to Annex B). However, the mini-slot must also be large enough to allow the transmission of the largest-sized data PDU (including physical layer overhead) in 255 mini-slots (see clause 8.3.3). The upper limit on mini-slot capacity is not specifically constrained, but in general is governed by channel efficiency and MAC performance issues. The valid range of the codes per mini-slot parameter is 2 to 32.
+
+**Number of active codes:** The number of active codes parameter allows the number of codes used to carry data to be less than or equal to 128. When the number of active codes is less than 128, low numbered codes starting with code 0 are not used, as shown in Figure 6-14.
+
+There are several reasons why it may be desirable to reduce the number of active codes:
+
+- Code 0 does not have the same spreading properties as the other codes and therefore under certain coloured noise conditions will degrade performance.
+- In extremely noisy plant conditions, a reduction in the number of active codes (along with the corresponding increase in power per code for the remaining codes) can allow reliable operation at reduced capacities. Reduction in active codes from 128 to 64 results in a 3 dB improvement in SNR.
+- The number of mini-slots per S-CDMA frame MUST be an integer. Therefore, the codes per mini-slot and number of active codes parameters MUST be chosen to result in an integral number of mini-slots per frame.
+
+The valid range of the *number of active codes* parameter is 64 to 128.
+
+A CMTS MUST support 126 and 128 active codes.
+
+A CM MUST support any nonprime number of active codes in the range of 64 to 128, inclusive.
+
+NOTE – When the number of active codes is 64 or greater, the S-CDMA frame must consist of more than one mini-slot, since the number of codes per mini-slot must be in the range 2 to 32. This implies that the number of active codes must be nonprime.
+
+The prime numbers between 64 and 128 are 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113 and 127.
+
+##### 6.2.11.2.2 Mini-slot numbering examples
+
+A typical mini-slot numbering example is shown in Figure 6-13. In this example, there are two codes per mini-slot defined. The number of codes per mini-slot is an adjustable parameter (via the UCD) to allow flexibility in determining the effective capacity of each mini-slot.
+
+![Figure 6-13: Mini-slot mapping with two codes per mini-slot, 128 active codes. The diagram shows a grid of mini-slots across three frames (f, f+1, f+2). Each frame contains K spreading intervals. Codes are assigned in pairs per mini-slot. For example, in Frame f, Code 127 and 126 are assigned to Mini-slot m+63, while Code 0 and 1 are assigned to Mini-slot m. Ellipses indicate intermediate codes and mini-slots.](255efa1d461fc79b4ed367aaec11637f_img.jpg)
+
+|          | ← K spreading intervals → | ← K spreading intervals → | ← K spreading intervals → |
+|----------|---------------------------|---------------------------|---------------------------|
+| Code 127 | Mini-slot $m+63$          | Mini-slot $m+127$         | Mini-slot $m+191$         |
+| Code 126 |                           |                           |                           |
+|          | ...                       | ...                       | ...                       |
+| Code 3   | Mini-slot $m+1$           | Mini-slot $m+65$          | Mini-slot $m+129$         |
+| Code 2   |                           |                           |                           |
+| Code 1   | Mini-slot $m$             | Mini-slot $m+64$          | Mini-slot $m+128$         |
+| Code 0   |                           |                           |                           |
+|          | Frame $f$                 | Frame $f+1$               | Frame $f+2$               |
+
+J.122\_F6-13
+
+Figure 6-13: Mini-slot mapping with two codes per mini-slot, 128 active codes. The diagram shows a grid of mini-slots across three frames (f, f+1, f+2). Each frame contains K spreading intervals. Codes are assigned in pairs per mini-slot. For example, in Frame f, Code 127 and 126 are assigned to Mini-slot m+63, while Code 0 and 1 are assigned to Mini-slot m. Ellipses indicate intermediate codes and mini-slots.
+
+**Figure 6-13 – Mini-slot mapping with two codes per mini-slot, 128 active codes**
+
+A second example, using three codes per mini-slot, is shown in Figure 6-14. Since it is required that there be an integral number of mini-slots per frame, the number of active codes has been restricted to 126 codes. In this example, a trade-off has been made to increase mapping flexibility at the expense of a small reduction in channel capacity (2/128).
+
+![Figure 6-14: Mini-slot mapping with three codes per mini-slot, 126 active codes. The diagram shows a grid of mini-slots across three frames (f, f+1, f+2). Each frame contains K spreading intervals. Codes are assigned in groups of three per mini-slot. For example, in Frame f, Codes 127, 126, and 125 are assigned to Mini-slot m+41, while Codes 0, 1, and 2 are assigned to Mini-slot m. Codes 3, 4, and 5 are assigned to Mini-slot m+1. Codes 6, 7, and 8 are assigned to Mini-slot m+43. Ellipses indicate intermediate codes and mini-slots. The bottom two rows (Code 1 and Code 0) are shaded, indicating they are not used in this configuration.](c419b566d720267c499087add1506018_img.jpg)
+
+|          | ← K spreading intervals → | ← K spreading intervals → | ← K spreading intervals → |
+|----------|---------------------------|---------------------------|---------------------------|
+| Code 127 | Mini-slot $m+41$          | Mini-slot $m+83$          | Mini-slot $m+125$         |
+| Code 126 |                           |                           |                           |
+| Code 125 |                           |                           |                           |
+|          | ...                       | ...                       | ...                       |
+| Code 7   | Mini-slot $m+1$           | Mini-slot $m+43$          | Mini-slot $m+85$          |
+| Code 6   |                           |                           |                           |
+| Code 5   |                           |                           |                           |
+| Code 4   | Mini-slot $m$             | Mini-slot $m+42$          | Mini-slot $m+84$          |
+| Code 3   |                           |                           |                           |
+| Code 2   |                           |                           |                           |
+| Code 1   |                           |                           |                           |
+| Code 0   |                           |                           |                           |
+|          | Frame $f$                 | Frame $f+1$               | Frame $f+2$               |
+
+J.122\_F6-14
+
+Figure 6-14: Mini-slot mapping with three codes per mini-slot, 126 active codes. The diagram shows a grid of mini-slots across three frames (f, f+1, f+2). Each frame contains K spreading intervals. Codes are assigned in groups of three per mini-slot. For example, in Frame f, Codes 127, 126, and 125 are assigned to Mini-slot m+41, while Codes 0, 1, and 2 are assigned to Mini-slot m. Codes 3, 4, and 5 are assigned to Mini-slot m+1. Codes 6, 7, and 8 are assigned to Mini-slot m+43. Ellipses indicate intermediate codes and mini-slots. The bottom two rows (Code 1 and Code 0) are shaded, indicating they are not used in this configuration.
+
+**Figure 6-14 – Mini-slot mapping with three codes per mini-slot, 126 active codes**
+
+There is no implication that physical layer processing is performed on a per mini-slot basis. As in a TDMA channel, the physical layer is concerned only with the burst start time (mini-slot number) and the burst length.
+
+#### 6.2.11.3 Transmission time
+
+Ideally, all the mini-slots contained in one S-CDMA frame are received simultaneously. These mini-slots may be transmitted from a single CM or may be transmitted from multiple CMs, as defined by the bandwidth allocation MAP message and the mini-slot mapping configuration settings (from the UCD). Note that a single CM may have more than one allocation active in a single S-CDMA frame.
+
+#### 6.2.11.4 Latency considerations
+
+S-CDMA frame timing is derived directly from (is phase-locked to) the 10.24-MHz CMTS master clock. Based on the allowable signalling rates and the fact that there are 128 signalling periods in a spreading interval, the S-CDMA frame time MUST always be a multiple of 25  $\mu\text{s}$ .
+
+Selecting the number of spreading intervals per frame and the signalling rate therefore exactly define the S-CDMA frame duration. As a specific example, a burst profile defined with 10 spreading intervals per frame with a signalling rate of 2.56 Mbaud would result in a frame duration of 500  $\mu\text{s}$ .
+
+The amount of additional upstream latency added by the use of S-CDMA mode is approximately one S-CDMA frame with the exact value described in clause 6.2.17.
+
+#### 6.2.11.5 Spreader-off bursts for maintenance on S-CDMA channel
+
+*Spreader-off* bursts are defined as bursts on an S-CDMA channel whose attributes specify that the spreader be turned off. For a spreader-off burst, both the S-CDMA framer and S-CDMA spreader are bypassed. The initial maintenance burst type MUST be specified (via UCD) to use spreader-off bursts. The station maintenance burst type MAY be specified (via UCD) to use spreader-off or spreader-on bursts. The CM MUST support both spreader-on and spreader-off modes for station maintenance bursts. All remaining IUC burst types MUST be specified (via UCD) to use spreader-on bursts. The S-CDMA channel will be programmed (via UCD) for  $C_{\text{ms}}$  codes per mini-slot,  $p$  number of active codes,  $K$  spreading intervals per S-CDMA frame, and a resultant  $s$  mini-slots per frame, where  $s = p/C_{\text{ms}}$ .
+
+Then each S-CDMA frame, where a transmission with the spreader-off is to occur, will contain exactly  $s$  mini-slots, where each mini-slot consists of  $C_{\text{ms}} \times K$  symbols.
+
+In the case where the number of active codes ( $p$ ) is less than 128, the frame will still contain exactly  $s$  mini-slots, where each mini-slot consists of  $C_{\text{ms}} \times K$  symbols. The first mini-slot of a frame will start with the first symbol of the frame. If a burst spans multiple frames, the burst will start relative to the first frame and continue without interruption into the next frame.
+
+Spreader-off bursts for station maintenance regions (IUC 4) MUST be padded with zero data symbols from the end of the R-S encoded data until the end of the burst as defined by the burst boundaries of clause 6.2.5.1.1. Spreader-off bursts for initial maintenance regions (IUC3) MUST be padded with zero data symbols from the end of the R-S encoded data until the end of the burst as defined by the burst boundaries of clause 6.2.5.1.1. Differential encoding and R-S byte interleaving MUST NOT be used with spreader-off bursts on S-CDMA channels.
+
+![Diagram of S-CDMA and spreader-off intervals showing frames f and f+1 for multiple codes.](51d4540605fdfa2c090638305022143b_img.jpg)
+
+The diagram illustrates the timing of S-CDMA frames and spreading intervals across multiple codes (0 to 127). At the top, three horizontal arrows indicate the duration of different interval types:  $K$  spreading intervals,  $128 K$  modulation intervals, and  $K$  spreading intervals. Below this, a grid shows the allocation of mini-slots for various codes across three frame periods: Frame  $f$ , Frame  $f+1$ , and Frame  $f+1$ . The codes are listed on the left: Code 127, Code 126, Code 125, Code 3, Code 2, Code 1, and Code 0. For Code 127 and Code 126, mini-slots  $m+63$  and  $m+191$  are shown in the first and third frame periods respectively. Code 125 shows three black squares representing bursts in the first and third frame periods. Codes 3, 2, 1, and 0 have mini-slots  $m+1$  and  $m$  in the first frame period, and  $m+129$  and  $m+128$  in the third frame period. The middle frame period ( $f+1$ ) contains vertical bars for mini-slots  $m+64$  through  $m+69$  and  $m+127$ , with three black squares indicating bursts for some codes. The bottom of the diagram labels the frame periods as 'Frame  $f$ ', 'Frame  $f+1$ ', and 'Frame  $f+1$ ', with the text 'Spreader-on frame' under each. A small label 'J.122\_F6-15' is in the bottom right corner.
+
+Diagram of S-CDMA and spreader-off intervals showing frames f and f+1 for multiple codes.
+
+**Figure 6-15 – S-CDMA and spreader-off intervals**
+
+The CMTS scheduler MUST ensure that the spreader-off interval is aligned to the start of an S-CDMA frame, occurs completely within one or more S-CDMA frames, and MUST ensure that no spreader-on bursts are scheduled during these same frames. The CMTS scheduler MUST grant at most one spreader-off burst per CM per frame. It is the responsibility of the CMTS to allocate mini-slots to the NULL SID, as required to prevent interference between bursts (i.e., before and after spreader-off bursts when the CM might not be sufficiently synchronized). Specifically, the CMTS MUST issue a NULL grant (to the NULL SID) of 1 mini-slot immediately before each spreader-off burst, which corresponds to either station maintenance or unicast initial maintenance, and MUST also issue a NULL grant (to the NULL SID) of 1 mini-slot or guarantee a quiet mini-slot (dead time), immediately after these bursts, and before a spreader-on interval starts.
+
+During spreader-off bursts on S-CDMA channels when less than 128 active codes are in use, the spreader-off frame will contain quiet mini-slots (dead time) equal to the number of inactive codes.
+
+#### 6.2.11.6 Limiting the number of codes assigned to a CM
+
+In certain situations, it may be useful for a CMTS to limit the number of codes that a single CM is required to simultaneously transmit. By doing so, the CM can divide its transmit power across a smaller number of codes than it would otherwise, which results in a higher power per code. This can be especially useful when a population of CMs is subject to an unusually high upstream
+
+attenuation, such that the CMs are transmitting at the maximum total transmit power. When the value of maximum scheduled codes is set less than the number of active codes, the CMTS MUST ensure that each compliant CM will not, via scheduled grants or multicast IEs with IUC=1, exceed its assigned maximum scheduled codes transmission limit in any S-CDMA frame. To accomplish this, the CMTS must avoid scenarios that would potentially cause the CM to attempt to transmit on more codes than its maximum scheduled code limit would allow. For instance, the CMTS must manage the number of codes assigned to contention IEs with IUC=1 in all frames. In frames where IEs with IUC=1 could not be inserted by a CMTS because of a CM's maximum scheduled codes, the CMTS MAY provide multicast IEs with IUC=2 for contention request opportunities. CMs with maximum scheduled codes enabled MUST be configurable via SNMP to control usage of IEs with IUC=2 [DOCS5]. By default, CMs with maximum scheduled codes enabled MUST NOT use IEs with IUC=2. Maximum scheduled codes MUST be equivalent to an integer number of mini-slots.
+
+A CM MUST NOT concatenate packets beyond the size permitted by the S-CDMA maximum scheduled codes, if maximum scheduled codes specified in the RNG-RSP is not 0. This is in order to reduce fragmentation overhead, which can become significant as the number of codes reduces. A CM receiving a maximum scheduled codes value MUST be capable of fragmenting any MAC frame, including frames transmitted prior to completing the registration process. To support 1.0 style configuration files, a CM and CMTS using the maximum scheduled codes value SHOULD support fragmentation in 1.0 mode.
+
+If a UGS flow is requested to provide an unsolicited grant size greater than the value permitted by the maximum scheduled codes value, the CMTS MUST reject the request for the UGS flow or change the CM's maximum scheduled codes value such that it would permit the UGS grants.
+
+### 6.2.12 S-CDMA framer
+
+The S-CDMA framer maps mini-slots to spreading codes and spreading intervals by arranging them as symbols within an S-CDMA frame. It also performs an interleaving function, to provide protection against impulse noise. The S-CDMA framer's function of mapping mini-slots to spreading codes and spreading intervals is illustrated in clause 6.2.11. As previously described, an S-CDMA frame is defined by the number of spreading intervals per frame, codes per mini-slot, and number of active codes. The framer uses this information to map the mini-slots of a transmission into frames. The framer maps complete grants so that any interleaving which is performed is not constrained by individual mini-slot boundaries. The framer MUST align transmissions to begin and end on mini-slot boundaries. Within a transmission, the framer numbers the symbols or bits and allocates them to codes and spreading intervals independent of the mini-slot mapping. When using TCM encoding, the TCM encoded symbols from the TCM encoder are split into two subsymbols consisting of the coded subsymbol which is the two bits and the parity generated from the convolution encoder, and the uncoded subsymbol consisting of the rest of the bits. When TCM is off, the randomizer output is treated as a continuous bit stream ignoring byte boundaries, as specified in clause 6.2.13.
+
+#### 6.2.12.1 Subframe definition
+
+The S-CDMA framer performs interleaving independently of mini-slots. Interleaving is constrained by subframe boundaries, where a subframe is a rectangular subset of an S-CDMA frame over which interleaving is performed. A subframe is normally an integer number of Reed-Solomon codewords to enhance protection from impulse noise.
+
+Given an S-CDMA frame which is N active codes by K spreading intervals, a subframe is defined to be a group of R contiguous rows, where R is an integer in the range from 1 to N. A subframe is defined to exist entirely within a single frame and does not span multiple frames. Each subframe contains  $R \times K$  locations and each location holds one symbol used for mapping and spreading. Each transmission MUST start with a new subframe. The last subframe of a frame MUST be shortened to fit entirely within a single S-CDMA frame, and the last subframe of a transmission MUST be
+
+shortened to fit within the granted mini-slots. In both of these cases, the subframe will be only  $R'$  rows instead of  $R$  rows where  $R' \leq R$ . Figure 6-16 shows a subframe consisting of  $R$  rows and  $K$  spreading intervals within an S-CDMA frame.
+
+![Diagram of subframe structure showing R rows and K spreading intervals. The vertical axis is labeled 'Number of active codes (N)' and the horizontal axis is labeled 'Spreading interval' with values 0, 1, ..., (K-1). Rows are labeled Row R, Row 2, Row 1. The top section is 'Other subframes'. The bottom section shows symbols being placed in a row-major order with an interleaver step size of 2.](3766b291e69420b0437ae278b057b5ee_img.jpg)
+
+The diagram illustrates the structure of a subframe within an S-CDMA frame. The vertical axis represents the 'Number of active codes (N)', and the horizontal axis represents the 'Spreading interval' from 0 to  $(K-1)$ . The subframe is divided into  $R$  rows, labeled from Row 1 at the bottom to Row  $R$  at the top. The top portion of the subframe is designated as 'Other subframes'. Below Row  $R$ , there are vertical ellipses indicating more rows. Below Row 2, there are horizontal ellipses indicating more rows. The bottom portion of the subframe shows symbols being placed into the grid. The symbols are placed in a row-major order, starting from Row 1, Spreading interval 0, and moving to Row 1, Spreading interval 2, then Row 1, Spreading interval 4, and so on, up to Row 1, Spreading interval  $(K-1)$ . This is followed by Row 2, Spreading interval 0, Row 2, Spreading interval 2, Row 2, Spreading interval 4, and so on. This pattern continues for all rows. The 'Other subframes' label in the bottom section indicates that the symbols shown are part of a larger subframe structure. The diagram is labeled J.122\_F6-16.
+
+Diagram of subframe structure showing R rows and K spreading intervals. The vertical axis is labeled 'Number of active codes (N)' and the horizontal axis is labeled 'Spreading interval' with values 0, 1, ..., (K-1). Rows are labeled Row R, Row 2, Row 1. The top section is 'Other subframes'. The bottom section shows symbols being placed in a row-major order with an interleaver step size of 2.
+
+Figure 6-16 – Subframe structure
+
+The parameters that define a subframe and the numbering within a subframe are *codes per subframe* and *interleaver step size*. These two parameters are specified as part of the burst attributes and can vary between burst profiles. These parameters determine the size of the subframe, and also how the subframe is filled with symbols. The valid range for *codes per subframe* is from 1 to the number of active codes in use. The parameter *interleaver step size* is used while putting TCM coded subsymbols and preamble symbols into the frame. Both of these types of symbols fill in subframes first along a row, and the *interleaver step size* parameter indicates the spreading interval increment to be used while filling in the symbols.
+
+#### 6.2.12.2 Framer operation
+
+The symbols entering the framer MUST be placed into the framer according to the following sets of rules. There are two sets of rules which apply to different types of input symbols. Preamble symbols and coded TCM subsymbols follow one set of rules, while non-TCM encoded symbols and uncoded TCM subsymbols follow the second set of rules. The rules are specified in the following clauses.
+
+##### 6.2.12.2.1 Rules for preamble and coded TCM symbols
+
+The preamble (whether TCM is on or off) and the coded TCM subsymbols MUST fill in the frame according to the following rules:
+
+- 1) The first symbol or subsymbol MUST be placed in the first spreading interval of the first row of the granted mini-slot. In Figure 6-16 this would be row 1, spreading interval 0, assuming that this is the start of the first mini-slot of the grant.
+- 2) Subsequent symbols MUST be placed at the next available spreading interval interleaver step size away from the previous. For instance, if the previous symbol was placed at spreading interval  $X$ , the next symbol is placed at  $X + \text{interleaver step size}$ .
+- 3) If the addition of the interleaver step size results in the next location being beyond the end of the frame, the next location MUST be located modulo the frame length. For instance, if  $J + \text{interleaver step size} = K + 1$ , then the next location would be spreading interval 1.
+- 4) If the next location is already occupied, then the spreading interval MUST be incremented by 1 until the next unoccupied spreading interval is located. For instance, if the desired location is spreading interval  $X$  and spreading interval  $X$  is occupied, but not  $X + 1$ , then  $X + 1$  would be used.
+- 5) After filling all of the spreading intervals of a single row, the operation is repeated starting with the next row and step 1 above.
+- 6) After placing all of the preamble and data symbols into the frame, the remaining symbols in the burst, as defined by the burst boundaries of clause 6.2.5.1.1 MUST be filled with zero data symbols which will be mapped to non-zero power.
+- 7) Any locations that have only a TCM uncoded subsymbol MUST be filled with zero bits in the coded subsymbol portion before mapping and spreading.
+
+##### 6.2.12.2.2 Rules for uncoded symbols and the uncoded TCM subsymbols
+
+Symbols without TCM encoding and uncoded TCM subsymbols MUST fill subframes according to the following rules:
+
+- 1) The first symbol MUST be placed in the first available code of the first available spreading interval of the subframe after the preamble has been placed into the frame. The symbols are filled from row 1 through row  $R$  and after filling a spreading interval, the next spreading interval is filled from row 1 through row  $R$ .
+- 2) Uncoded symbols and the uncoded portion of TCM symbols MUST NOT be placed in the same frame location (spreading interval, code) as a preamble symbol. For instance, if there is a preamble symbol in row  $X$ , spreading interval  $Y$ ; and row  $(X + 1)$ , spreading interval  $Y$  is unused, the symbol should be placed into row  $(X + 1)$ , spreading interval  $Y$ .
+- 3) Subsequent symbols MUST be placed in the next available row of the first available spreading interval of the current subframe. This causes the subframe to be filled column-wise bottom to top and then from left to right. For instance, if row 1 through row  $R$  of spreading interval  $X$  is already occupied, the next symbol would be placed into the first available row of spreading interval  $X + 1$ .
+- 4) After completely filling a subframe, the next subframe MUST begin as specified in step 1 above.
+- 5) The number of rows contained in the last subframe of a frame MUST be reduced to fit entirely within the frame if there is not adequate space for a full subframe.
+- 6) The number of rows contained in the last subframe of a grant of mini-slots MUST be reduced to fit entirely within the granted mini-slots if there is not adequate space for a full subframe within the grant.
+
+- 7) After placing all of the data symbols into the frame, the remaining symbols in the burst, as defined by the burst boundaries of clause 6.2.5.1.1, MUST be filled with zero data symbols which will be mapped to non-zero power.
+- 8) Any locations that have only a TCM coded subsymbol MUST be filled with zero bits in the uncoded subsymbol portion before mapping and spreading.
+
+##### 6.2.12.2.3 Subframe example
+
+Figure 6-17 below shows an example which follows the above specified rules. Each box in the figure represents a symbol that can contain either a preamble symbol, an uncoded symbol when not using TCM, or an uncoded and coded subsymbol when using TCM. In this example there are 9 spreading intervals in the frame, 3 rows for the subframe, an interleaver step size of 3, and the preamble is 4 symbols. Based on these parameters, the subframe would be filled as shown. If the data is TCM encoded, the Cs would represent locations of the coded subsymbols and the Us represent the locations of the uncoded subsymbols. If the TCM is not used, then the symbols would be placed according to the Us only.
+
+![Figure 6-17: Symbol numbering without TCM. A 3x9 grid showing symbol placement for preamble (P), uncoded (U), and coded (C) subsymbols. The grid illustrates interleaving and spreading patterns.](fd3cbb53e991f8209ba17b398f426e13_img.jpg)
+
+Frame length
+
+3 rows
+
+|                                   |                                   |                                   |                                   |                                    |                                    |                                    |                                    |                                    |
+|-----------------------------------|-----------------------------------|-----------------------------------|-----------------------------------|------------------------------------|------------------------------------|------------------------------------|------------------------------------|------------------------------------|
+| U <sup>1</sup><br>C <sup>14</sup> | U <sup>3</sup><br>C <sup>17</sup> | U <sup>6</sup><br>C <sup>20</sup> | U <sup>8</sup><br>C <sup>15</sup> | U <sup>11</sup><br>C <sup>18</sup> | U <sup>14</sup><br>C <sup>21</sup> | U <sup>16</sup><br>C <sup>16</sup> | U <sup>19</sup><br>C <sup>19</sup> | U <sup>22</sup><br>C <sup>22</sup> |
+| U <sup>0</sup><br>C <sup>5</sup>  | U <sup>2</sup><br>C <sup>8</sup>  | U <sup>5</sup><br>C <sup>11</sup> | U <sup>7</sup><br>C <sup>8</sup>  | U <sup>10</sup><br>C <sup>9</sup>  | U <sup>13</sup><br>C <sup>12</sup> | U <sup>15</sup><br>C <sup>7</sup>  | U <sup>18</sup><br>C <sup>10</sup> | U <sup>21</sup><br>C <sup>13</sup> |
+| P <sup>0</sup>                    | P <sup>3</sup>                    | U <sup>4</sup><br>C <sup>2</sup>  | P <sup>1</sup>                    | U <sup>9</sup><br>C <sup>0</sup>   | U <sup>12</sup><br>C <sup>3</sup>  | P <sup>2</sup>                     | U <sup>17</sup><br>C <sup>1</sup>  | U <sup>20</sup><br>C <sup>4</sup>  |
+
+step = 3
+
+J.122\_F6-17
+
+Figure 6-17: Symbol numbering without TCM. A 3x9 grid showing symbol placement for preamble (P), uncoded (U), and coded (C) subsymbols. The grid illustrates interleaving and spreading patterns.
+
+Figure 6-17 – Symbol numbering without TCM
+
+##### 6.2.12.2.4 Frame transmission
+
+Once a frame is completed and ready for transmission, the symbols MUST be mapped and spread in spreading interval order. This means that spreading interval 0, as described in Figure 6-16, MUST be the first spreading interval on the wire. For TCM encoded data, the coded and uncoded subsymbols from each location in the frame MUST be combined to create complete symbols before mapping and spreading. This corresponds to creating a new symbol where the coded portion of the symbol is  $C^i$  and the uncoded portion is  $U^j$ . The preamble symbols remain intact.
+
+### 6.2.13 Symbol mapping
+
+The modulation mode is configurable via MAC messages. Differential encoded QPSK and 16QAM are available for TDMA channels. QPSK, 8QAM, 16QAM, 32QAM and 64QAM are available for TDMA and S-CDMA channels. TCM-encoded QPSK, 8QAM, 16QAM, 32QAM, 64QAM and 128QAM are available for S-CDMA channels. The symbols transmitted in each mode and the mapping of the input bits to the I and Q constellation MUST be as defined in Table 6-3. In the table,  $x^1$  represents the LSB of each of the symbol maps and  $x^2$ ,  $x^3$ ,  $x^4$ ,  $x^5$ ,  $x^6$  and  $x^7$  represents the MSB for QPSK, 8QAM, 16QAM, 32QAM, 64QAM and 128QAM, respectively. The MSB MUST be the
+
+first bit in the serial data into the symbol mapper and it MUST be mapped to the MSB of the symbol map. The number of data bytes may not map into an integer number of symbols. In this case, the last symbol MUST be padded with zero bits in the LSB locations after all data bits are processed.
+
+**Table 6-3 – I/Q mapping**
+
+| <b>QAM mode</b> | <b>Input bit definitions</b>  |
+|-----------------|-------------------------------|
+| QPSK            | $x^2 x^1$                     |
+| 8QAM            | $x^3 x^2 x^1$                 |
+| 16QAM           | $x^4 x^3 x^2 x^1$             |
+| 32QAM           | $x^5 x^4 x^3 x^2 x^1$         |
+| 64QAM           | $x^6 x^5 x^4 x^3 x^2 x^1$     |
+| 128QAM          | $x^7 x^6 x^5 x^4 x^3 x^2 x^1$ |
+
+All constellations are defined on a common integer grid in Figure 6-18. This defines each QAM symbol with 5-bit values on each (I and Q) axis. The relative symbol amplitudes defined by the grid MUST be maintained across all constellations. Different constellations may be used, for example, in different burst profiles, in preamble and data symbols within the same burst, and in modulating different spreading codes within a frame.
+
+In Figure 6-18,  $E_{av}$  denotes the average constellation energy for equally likely symbols. For each constellation, the integer values of  $E_{av}$  and differences in dB compared to 64QAM,  $G_{const}$ , are given. The QPSK0 constellation is employed for low-power preamble and QPSK data symbols. Use of QPSK1 is restricted to high-power preamble symbols.
+
+The upstream symbol constellations MUST be as shown in Figure 6-18.
+
+The upstream QPSK Gray-coded and differential symbol mapping MUST be as shown in Figure 6-19.
+
+The upstream 8QAM symbol mapping MUST be as shown in Figure 6-20.
+
+The upstream 16QAM Gray-coded symbol mapping MUST be as shown in Figure 6-21.
+
+The upstream 16QAM differential symbol mapping MUST be as shown in Figure 6-21.
+
+The upstream 32QAM symbol mapping MUST be as shown in Figure 6-22.
+
+The upstream 64QAM Gray-coded symbol mapping MUST be as shown in Figure 6-23.
+
+The TCM symbol mappings used for S-CDMA are shown in Figure 6-24 through Figure 6-26.
+
+The upstream QPSK TCM symbol mapping MUST be as shown in Figure 6-24.
+
+The upstream 8QAM TCM symbol mapping MUST be as shown in Figure 6-24.
+
+The upstream 16QAM TCM symbol mapping MUST be as shown in Figure 6-25.
+
+The upstream 32QAM TCM symbol mapping MUST be as shown in Figure 6-25.
+
+The upstream 64QAM TCM symbol mapping MUST be as shown in Figure 6-26.
+
+The upstream 128QAM TCM symbol mapping MUST be as shown in Figure 6-26.
+
+If differential quadrant encoding is enabled, then the currently-transmitted symbol quadrant is derived from the previously transmitted symbol quadrant and the current input bits via Table 6-4. If differential quadrant encoding is enabled, the upstream PMD sublayer MUST apply these differential encoding rules to all transmitted symbols (including those that carry preamble bits).
+
+Differential quadrant encoding is only available for QPSK and 16QAM on TDMA channels. In Table 6-4, I(1) Q(1) refers to  $x^2x^1$  and  $x^4x^3$  from Table 6-3 for QPSK and 16QAM cases respectively.
+
+**Table 6-4 – Definition of differential quadrant coding**
+
+| Current input bits<br>I(1) Q(1) | Quadrant<br>phase change | MSBs of previously<br>transmitted symbol | MSBs for currently<br>transmitted symbol |
+|---------------------------------|--------------------------|------------------------------------------|------------------------------------------|
+| 00                              | 0°                       | 11                                       | 11                                       |
+| 00                              | 0°                       | 01                                       | 01                                       |
+| 00                              | 0°                       | 00                                       | 00                                       |
+| 00                              | 0°                       | 10                                       | 10                                       |
+| 01                              | 90°                      | 11                                       | 01                                       |
+| 01                              | 90°                      | 01                                       | 00                                       |
+| 01                              | 90°                      | 00                                       | 10                                       |
+| 01                              | 90°                      | 10                                       | 11                                       |
+| 11                              | 180°                     | 11                                       | 00                                       |
+| 11                              | 180°                     | 01                                       | 10                                       |
+| 11                              | 180°                     | 00                                       | 11                                       |
+| 11                              | 180°                     | 10                                       | 01                                       |
+| 10                              | 270°                     | 11                                       | 10                                       |
+| 10                              | 270°                     | 01                                       | 11                                       |
+| 10                              | 270°                     | 00                                       | 01                                       |
+| 10                              | 270°                     | 10                                       | 00                                       |
+
+**QPSK0:**  $E_{av} = 128$  ( $G_{const} = -1.18$  dB rel to 64QAM)
+
+**QPSK1:**  $E_{av} = 288$  ( $G_{const} = +2.34$  dB)
+
+![QPSK0 and QPSK1 symbol constellations. The plot shows the real part (in-phase) on the x-axis and the imaginary part (quadrature) on the y-axis. QPSK0 points are at (±8, ±8) and QPSK1 points are at (±12, ±12).](bc53843127b23a7d84a6184c283d3361_img.jpg)
+
+QPSK0 and QPSK1 symbol constellations. The plot shows the real part (in-phase) on the x-axis and the imaginary part (quadrature) on the y-axis. QPSK0 points are at (±8, ±8) and QPSK1 points are at (±12, ±12).
+
+**8QAM-DS:**  $E_{av} = 160$  ( $G_{const} = -0.21$  dB)
+
+![8QAM-DS symbol constellation. The plot shows 8 points arranged in a square grid with side length 8, centered at the origin. The axes range from -12 to 12.](0775f419af4e481eea2fb9706fe0b035_img.jpg)
+
+8QAM-DS symbol constellation. The plot shows 8 points arranged in a square grid with side length 8, centered at the origin. The axes range from -12 to 12.
+
+**16QAM-SQ:**  $E_{av} = 160$  ( $G_{const} = -0.21$  dB)
+
+![16QAM-SQ symbol constellation. The plot shows 16 points arranged in a 4x4 square grid with side length 4, centered at the origin. The axes range from -12 to 12.](70546cb98239089866510133c7fbc169_img.jpg)
+
+16QAM-SQ symbol constellation. The plot shows 16 points arranged in a 4x4 square grid with side length 4, centered at the origin. The axes range from -12 to 12.
+
+**32QAM-DS:**  $E_{av} = 168$  ( $G_{const} = 0$  dB)
+
+![32QAM-DS symbol constellation. The plot shows 32 points arranged in a grid with side length 2, centered at the origin. The axes range from -14 to 14.](1f1ca53cce40d1c5f03ac6b5c94b4e6b_img.jpg)
+
+32QAM-DS symbol constellation. The plot shows 32 points arranged in a grid with side length 2, centered at the origin. The axes range from -14 to 14.
+
+**64QAM-SQ:**  $E_{av} = 168$  ( $G_{const} = 0$  dB)
+
+![64QAM-SQ symbol constellation. The plot shows 64 points arranged in an 8x8 square grid with side length 2, centered at the origin. The axes range from -14 to 14.](764798e389e91d9e766dfad263b6e241_img.jpg)
+
+64QAM-SQ symbol constellation. The plot shows 64 points arranged in an 8x8 square grid with side length 2, centered at the origin. The axes range from -14 to 14.
+
+**128QAM-DS:**  $E_{av} = 170$  ( $G_{const} = 0.05$  dB)
+
+![128QAM-DS symbol constellation. The plot shows 128 points arranged in a dense grid with side length 1, centered at the origin. The axes range from -15 to 15. A label 'J.122_F6-18' is present at the bottom right.](fcd880b51697eb8795dabe8dea711a51_img.jpg)
+
+128QAM-DS symbol constellation. The plot shows 128 points arranged in a dense grid with side length 1, centered at the origin. The axes range from -15 to 15. A label 'J.122\_F6-18' is present at the bottom right.
+
+**Figure 6-18 – Symbol constellations**
+
+![QPSK Gray-coded and differential symbol mapping diagram. It shows a square constellation in the I-Q plane with four points: 01 (top-left), 11 (top-right), 00 (bottom-left), and 10 (bottom-right). The axes are labeled I (horizontal) and Q (vertical). Above the top-right point, the text 'Label bits x^2 x^1 (I,Q)' is present. A small label 'J.122_F6-19' is at the bottom right.](7e5f8a1e5575ef87a54c9c091eaaa66d_img.jpg)
+
+QPSK Gray-coded and differential symbol mapping diagram. It shows a square constellation in the I-Q plane with four points: 01 (top-left), 11 (top-right), 00 (bottom-left), and 10 (bottom-right). The axes are labeled I (horizontal) and Q (vertical). Above the top-right point, the text 'Label bits x^2 x^1 (I,Q)' is present. A small label 'J.122\_F6-19' is at the bottom right.
+
+Figure 6-19 – QPSK Gray-coded and differential symbol mapping
+
+![8QAM symbol mapping diagram. It shows a constellation of eight points in the I-Q plane, arranged in a diamond shape. The points are labeled with 3-bit bit sequences: 111 (top), 101 (top-right), 110 (left), 011 (right), 010 (bottom-left), 001 (bottom-right), 100 (far-left), and 000 (far-right). The axes are labeled I (horizontal) and Q (vertical). Above the top-right point, the text 'Label bits x^3 x^2 x^1' is present. There are two curved arrows with '(2)' inside them, indicating Gray-code violations between adjacent points 101 and 111, and between 100 and 010. To the right of the constellation, there is a symbol with '(2)' and the text 'Gray-code violation'. A small label 'J.122_F6-20' is at the bottom.](750677d35a0db0f1a6d44ede4e11d347_img.jpg)
+
+8QAM symbol mapping diagram. It shows a constellation of eight points in the I-Q plane, arranged in a diamond shape. The points are labeled with 3-bit bit sequences: 111 (top), 101 (top-right), 110 (left), 011 (right), 010 (bottom-left), 001 (bottom-right), 100 (far-left), and 000 (far-right). The axes are labeled I (horizontal) and Q (vertical). Above the top-right point, the text 'Label bits x^3 x^2 x^1' is present. There are two curved arrows with '(2)' inside them, indicating Gray-code violations between adjacent points 101 and 111, and between 100 and 010. To the right of the constellation, there is a symbol with '(2)' and the text 'Gray-code violation'. A small label 'J.122\_F6-20' is at the bottom.
+
+Figure 6-20 – 8QAM symbol mapping
+
+![Figure 6-21a: 16QAM symbol mapping diagram showing a 4x4 grid of symbols in the I-Q plane. The mapping is Gray-coded (I,Q,I,Q). The axes are labeled I and Q. Symbols are 4-bit binary strings. Figure 6-21b: 16QAM symbol mapping diagram showing a 4x4 grid of symbols in the I-Q plane. The mapping is for differential encoding. The axes are labeled I and Q. Symbols are 4-bit binary strings.](c2e29ea8ce248c31df2f0aba049d018c_img.jpg)
+
+Label bits  $x^4 x^3 x^2 x^1$
+
+a) Gray-coded Mapping (I,Q,I,Q)
+
+b) Mapping for differential Encoding
+
+J.122\_F6-21
+
+Figure 6-21a: 16QAM symbol mapping diagram showing a 4x4 grid of symbols in the I-Q plane. The mapping is Gray-coded (I,Q,I,Q). The axes are labeled I and Q. Symbols are 4-bit binary strings. Figure 6-21b: 16QAM symbol mapping diagram showing a 4x4 grid of symbols in the I-Q plane. The mapping is for differential encoding. The axes are labeled I and Q. Symbols are 4-bit binary strings.
+
+**Figure 6-21 – 16QAM symbol mapping**
+
+![Figure 6-22: 32QAM symbol mapping diagram showing a grid of 32 symbols in the I-Q plane. The mapping is a 4x8 grid of symbols, with some symbols marked with '(2)' indicating they are double symbols. The axes are labeled I and Q. Symbols are 5-bit binary strings.](d71ba79c3da3a9767a82812c7eb0b20b_img.jpg)
+
+Label bits  $x^5 x^4 x^3 x^2 x^1$
+
+J.122\_F6-22
+
+Figure 6-22: 32QAM symbol mapping diagram showing a grid of 32 symbols in the I-Q plane. The mapping is a 4x8 grid of symbols, with some symbols marked with '(2)' indicating they are double symbols. The axes are labeled I and Q. Symbols are 5-bit binary strings.
+
+**Figure 6-22 – 32QAM symbol mapping**
+
+![64QAM symbol mapping diagram showing an 8x8 grid of 64 symbols with binary labels. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'.](ce857617d1453e7e90edfaae561e2f62_img.jpg)
+
+Q
+
+Label bits  $x^6 x^5 x^4 x^3 x^2 x^1$  (I,Q,I,Q,I,Q)
+
+|        |        |        |        |        |        |        |        |
+|--------|--------|--------|--------|--------|--------|--------|--------|
+| 011100 | 011110 | 010110 | 010100 | 110100 | 110110 | 111110 | 111100 |
+| 011101 | 011111 | 010111 | 010101 | 110101 | 110111 | 111111 | 111101 |
+| 011001 | 011011 | 010011 | 010001 | 110001 | 110011 | 111011 | 111001 |
+| 011000 | 011010 | 010010 | 010000 | 110000 | 110010 | 111010 | 111000 |
+| 001000 | 001010 | 000010 | 000000 | 100000 | 100010 | 101010 | 101000 |
+| 001001 | 001011 | 000011 | 000001 | 100001 | 100011 | 101011 | 101001 |
+| 001101 | 001111 | 000111 | 000101 | 100101 | 100111 | 101111 | 101101 |
+| 001100 | 001110 | 000110 | 000100 | 100100 | 100110 | 101110 | 101100 |
+
+J.122\_F6-23
+
+64QAM symbol mapping diagram showing an 8x8 grid of 64 symbols with binary labels. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'.
+
+**Figure 6-23 – 64QAM symbol mapping**
+
+![QPSK symbol mapping diagram showing four symbols (01, 00, 10, 11) on a grid. 8QAM TCM symbol mapping diagram showing eight symbols (111, 101, 010, 000, 001, 011, 100, 110) on a grid.](57e7a913a27e03b719a102d02c6bf985_img.jpg)
+
+Binary labels  $x^2 x^1$
+
+|             |             |
+|-------------|-------------|
+| 01 (yellow) | 00 (cyan)   |
+| 10 (cyan)   | 11 (yellow) |
+
+Binary labels  $x^3 x^2 x^1$
+
+|            |  |              |  |  |              |  |  |
+|------------|--|--------------|--|--|--------------|--|--|
+|            |  | 111 (yellow) |  |  | 101 (yellow) |  |  |
+| 010 (cyan) |  |              |  |  | 000 (cyan)   |  |  |
+|            |  | 001 (yellow) |  |  | 011 (yellow) |  |  |
+| 100 (cyan) |  |              |  |  | 110 (cyan)   |  |  |
+
+J.122\_F6-24
+
+QPSK symbol mapping diagram showing four symbols (01, 00, 10, 11) on a grid. 8QAM TCM symbol mapping diagram showing eight symbols (111, 101, 010, 000, 001, 011, 100, 110) on a grid.
+
+**Figure 6-24 – QPSK and 8QAM TCM symbol mapping**
+
+![16QAM symbol mapping diagram showing a 4x4 grid of symbols. The grid is divided into four quadrants by a vertical and a horizontal line. Symbols are labeled with octal values 00-17. Subset B0 (blue) includes 16, 12, 04, 00, 02, 06, 10, 14. Subset B1 (yellow) includes 13, 07, 01, 15, 17, 03, 05, 11. 32QAM symbol mapping diagram showing a cross-shaped constellation. Symbols are labeled with octal values 00-37. Subset B0 (blue) includes 26, 34, 16, 24, 10, 02, 00, 32, 36, 04, 06, 14, 20, 12, 30, 22. Subset B1 (yellow) includes 23, 31, 13, 21, 15, 07, 05, 37, 33, 01, 03, 11, 25, 17, 35, 27.](8605b43090d582ea5046e1804178a7d8_img.jpg)
+
+Octal labels  $o^2 o^1$  (= bin. labels  $x^4 x^3 x^2 x^1$ )
+
+Octal labels  $o^2 o^1$  (= bin. labels  $x^5 x^4 x^3 x^2 x^1$ )
+
+Subset B0
+Subset B1
+J.122\_F6-25
+
+16QAM symbol mapping diagram showing a 4x4 grid of symbols. The grid is divided into four quadrants by a vertical and a horizontal line. Symbols are labeled with octal values 00-17. Subset B0 (blue) includes 16, 12, 04, 00, 02, 06, 10, 14. Subset B1 (yellow) includes 13, 07, 01, 15, 17, 03, 05, 11. 32QAM symbol mapping diagram showing a cross-shaped constellation. Symbols are labeled with octal values 00-37. Subset B0 (blue) includes 26, 34, 16, 24, 10, 02, 00, 32, 36, 04, 06, 14, 20, 12, 30, 22. Subset B1 (yellow) includes 23, 31, 13, 21, 15, 07, 05, 37, 33, 01, 03, 11, 25, 17, 35, 27.
+
+**Figure 6-25 – 16QAM and 32QAM TCM symbol mapping**
+
+![64QAM symbol mapping diagram showing an 8x8 grid. Symbols are labeled with octal values 00-77. Blue boxes represent Subset B0 and yellow boxes represent Subset B1 in a checkerboard-like pattern. 128QAM symbol mapping diagram showing a dense cross-shaped constellation. Symbols are labeled with octal values 000-177. Blue boxes represent Subset B0 and yellow boxes represent Subset B1.](14294c70b5a0effb6bdaf09c46bbdc9f_img.jpg)
+
+64QAM: octal labels  $o^3 o^2 o^1$   
+(= bin. labels  $x^6 x^5 x^4 x^3 x^2 x^1$ )
+
+128QAM: octal labels  $o^3 o^2 o^1$   
+(= bin. labels  $x^7 x^6 x^5 x^4 x^3 x^2 x^1$ )
+
+Subset B0
+Subset B1
+J.122\_F6-26
+
+64QAM symbol mapping diagram showing an 8x8 grid. Symbols are labeled with octal values 00-77. Blue boxes represent Subset B0 and yellow boxes represent Subset B1 in a checkerboard-like pattern. 128QAM symbol mapping diagram showing a dense cross-shaped constellation. Symbols are labeled with octal values 000-177. Blue boxes represent Subset B0 and yellow boxes represent Subset B1.
+
+**Figure 6-26 – 64QAM and 128QAM TCM symbol mapping**
+
+### 6.2.14 S-CDMA spreader
+
+The basis of signal transmission with S-CDMA is direct-sequence spread-spectrum modulation. S-CDMA employs a family of orthogonal digital code words, called spreading codes, to simultaneously transmit up to 128 modulation symbols. In each spreading interval, a vector,  $\bar{P}_k$ , is transmitted such that:
+
+$$\bar{P}_k = \bar{S}_k \times C$$
+
+where  $\bar{S}_k$  is a vector,  $[s_{k,127}, s_{k,126}, \dots, s_{k,0}]$ , of modulation symbols on the integer grid of clause 6.2.13 to be transmitted in spreading interval  $k$ , and  $C$  is a matrix:
+
+$$C = \begin{bmatrix} c_{127,127} & c_{127,126} & \dots & c_{127,0} \\ c_{126,127} & c_{126,126} & \dots & c_{126,0} \\ \dots & \dots & \dots & \dots \\ c_{0,127} & c_{0,126} & \dots & c_{0,0} \end{bmatrix} = \begin{bmatrix} x_1 & x_{127} & \dots & x_2 & -1 \\ x_2 & x_1 & \dots & x_3 & -1 \\ \dots & \dots & \dots & \dots & -1 \\ x_{127} & x_{126} & \dots & x_1 & -1 \\ 1 & 1 & 1 & 1 & 1 \end{bmatrix}$$
+
+where the rows of  $C$  are the 128 spreading codes such that  $Code(j) = [c_{j,127}, c_{j,126}, \dots, c_{j,0}]$ . The result of the spreading operation is the transmission vector  $\bar{P}_k$ , which has 128 elements,  $[P_{k,127}, P_{k,126}, \dots, P_{k,0}]$ , where each element is transmitted at the signalling rate, with element  $P_{k,0}$  transmitted first in time. The first element  $S_0$  into the spreader is defined as follows. As a point of reference, for 128 allocated codes, and considering the first column of the framer ( $k = 0$ ),  $S_0$  is the first symbol in time to enter the framer, occupies the lower left element of the framer, and is the first element into the spreader.
+
+The set of orthogonal codes used for the spreading operation is quasi-cyclic and consists of values that are either +1 or -1.  $Code(0)$  consists of 128 elements all of which have a value of +1. For each of the other spreading codes  $Code(j)$ , the element  $c_{j,0}$  is -1 and the remaining elements are obtained by a cyclic shift of a sequence  $x$  as is shown in the above matrix in this clause.
+
+The sequence  $x_i$  is defined such that the elements corresponding to the following set of indices are equal to -1:
+
+```
+{ 2 3 4 5 6 7 9 10 11 13 16 17 18 19 20 21 25 26
+  28 30 31 33 34 35 37 39 40 41 49 51 52 55 56 59 60 61
+  65 66 67 69 72 73 74 77 78 79 81 84 90 92 94 97 100 101
+  103 106 109 110 111 114 117 119 121 };
+```
+
+the remaining elements of  $Code(1)$  have a value of +1.
+
+Each  $Code(j)$  is obtained by cyclic shift to the left (in the direction of increasing indices) of  $Code(j-1)$  where the element,  $c_{j,0}$ , has a value of -1 and does not take part in the cyclic shift.
+
+Although each code is defined to have equal power, the spread symbols may have slightly unequal power since the symbols at the input to the spreader have varying values of  $E_{av}$  according to the integer symbol grid of clause 6.2.13.
+
+If a CM has not been assigned to use a particular code,  $j$ , at a spreading time interval,  $k$ , then in its computation of its transmission vector  $\bar{P}_k$ , it will set  $s_{k,j}$  to numerical zero. The assignment of codes to the CM is performed by the framer as it assigns a burst of symbols a particular order in the two-dimensional space of codes and time. This symbol sequencing is described in detail in clause 6.2.12.
+
+The I and Q components of the symbols are spread using the same spreading code.
+
+It is also important to note that in the matrix multiplication of the equation above and subsequent CM processing prior to the D/A, there is an essential clipping operation wherein – as an example – filtered (pulse shaped) elements of  $\bar{P}_k$  in excess of some vendor-specific absolute value are clipped (retaining complex angle) to this absolute value. This non-linear operation, deviating from the equation above and the subsequent linear processing prior to the D/A, is essential for meeting spurious emission and MER requirements safely and efficiently while operating at the highest CM average transmit power levels (see Table 6-8).
+
+#### 6.2.14.1 Code hopping
+
+Code hopping refers to a systematic re-ordering of the rows of the spreading matrix,  $C$ , at each spreading interval,  $k$ . The code-hopping algorithm uses a pseudo-random number,  $lfsr\_out(k)$ , to determine a cyclic shift of the rows of the matrix  $C$ . When the number of active codes equals 128, the code-hopping algorithm uses all codes. When the number of active codes is less than 128, the code-hopping algorithm hops only over the cyclic codes ( $Code(0)$ , the all 1s code, is excluded). The generalization of the spreading matrix at spreading interval,  $k$ , is given by (where matrix elements,  $c_{j,i}$ , are as defined above in clause 6.2.14):
+
+$$C_k = \begin{pmatrix} c_{f(k,127),127} & c_{f(k,127),126} & \dots & c_{f(k,127),0} \\ c_{f(k,126),127} & c_{f(k,126),126} & \dots & c_{f(k,126),0} \\ \dots & \dots & \dots & \dots \\ c_{f(k,0),127} & c_{f(k,0),126} & \dots & c_{f(k,0),0} \end{pmatrix}$$
+
+where:
+
+$$f(k,i) = \begin{cases} \text{modulo}[(128 - lfsr\_out(k) + i), 128] & \text{with } 0 \leq i \leq 127 \text{ for 128 active codes} \\ \text{modulo}[(126 - lfsr\_out(k) + i), 127] + 1 & \text{with } 1 \leq i \leq 127 \text{ for } < 128 \text{ active codes} \end{cases}$$
+
+In S-CDMA mode, the CM MUST support code hopping.
+
+Note that when the number of active codes is less than 128, the unused codes are those starting with matrix index 0. In this case, the code hopping continues to "hop" over all of the codes except for  $Code(0)$ , even if the number of active codes is less than 127.
+
+The pseudo-random number generator which determines the spreading matrix reordering is the linear-feedback shift register (LFSR) which is shown in Figure 6-27. In order to align the CM's code-hopping pseudo-random sequence with that at the CMTS, the pseudo random generator must output the following value at the first spreading interval of each frame:
+
+$$lfsr\_out(\text{frame\_number} * \text{spreading\_interval\_per\_frame})$$
+
+where  $lfsr\_out(k)$  is the value of  $lfsr\_out$  after  $k$  shifts following the code hopping seed load into the LFSR<sup>32</sup> (the description of the frame counter and the procedures for its synchronization are contained in clause 6.2.11.2, "Mini-slot numbering"). At this reset, a 15-bit initialization value (seed) is loaded into the shift register and is used at the first spreading interval. Then at each subsequent spreading interval,  $k$ , a new bit is shifted into the LFSR producing a new 7-bit value,  $lfsr\_out(k)$ . This value is used, with bit 7 as the MSB, to compute the spreading matrix indices as given by the equation above. Note that the code-hopping mechanism (LFSR, spreading interval index) is advanced every spreading interval (128 modulation intervals) in both spreader-on and spreader-off frames.
+
+![Figure 6-27: Code-hopping random number generator diagram. It shows a 15-bit shift register with cells numbered 1 to 15. An 'Initialization value (seed)' is input to all cells. The output of cell 15 is fed back through an XOR gate to the input of cell 1. The outputs of cells 1, 2, 3, 4, 5, 6, 7, and 15 are combined into a 7-bit bus labeled 'lfsr_out'. A small '7' is next to the bus label. The diagram is labeled J.122_F6-27 in the bottom right corner.](b20942bb14022381a243971ab9790dd9_img.jpg)
+
+Figure 6-27: Code-hopping random number generator diagram. It shows a 15-bit shift register with cells numbered 1 to 15. An 'Initialization value (seed)' is input to all cells. The output of cell 15 is fed back through an XOR gate to the input of cell 1. The outputs of cells 1, 2, 3, 4, 5, 6, 7, and 15 are combined into a 7-bit bus labeled 'lfsr\_out'. A small '7' is next to the bus label. The diagram is labeled J.122\_F6-27 in the bottom right corner.
+
+**Figure 6-27 – Code-hopping random number generator**
+
+The 15-bit seed value is configured in response to the upstream channel descriptor message from the CMTS.
+
+### 6.2.15 Transmit pre-equalizer
+
+A transmit pre-equalizer of a linear equalizer structure, as shown in Figure 6-28, MUST be configured by the CM in response to the ranging response (RNG-RSP) message transmitted by the CMTS.
+
+![Figure 6-28: Transmit pre-equalizer structure diagram. An 'I-Q Input' enters a series of delay blocks labeled <math>z^{-1}</math>. Between each <math>z^{-1}</math> block, a tap is taken, passed through a gain block (<math>F_1, F_2, F_3, F_4, ..., F_{17}, F_{18}, ..., F_{24}</math>), and then summed with the main signal path at a summation node (represented by a circle with a plus sign). The final output is labeled 'Equalizer Output'. The diagram is labeled J.122_F6-28 in the bottom right corner.](aa6e28822419dba9f22129fee66c9c4c_img.jpg)
+
+Figure 6-28: Transmit pre-equalizer structure diagram. An 'I-Q Input' enters a series of delay blocks labeled  $z^{-1}$ . Between each  $z^{-1}$  block, a tap is taken, passed through a gain block ( $F_1, F_2, F_3, F_4, ..., F_{17}, F_{18}, ..., F_{24}$ ), and then summed with the main signal path at a summation node (represented by a circle with a plus sign). The final output is labeled 'Equalizer Output'. The diagram is labeled J.122\_F6-28 in the bottom right corner.
+
+**Figure 6-28 – Transmit pre-equalizer structure**
+
+There are two modes of operation for the pre-equalizer of a CM: DOCS 1.1 mode, and DOCS 2.0 mode. In DOCS 1.1 mode, the CM MUST support a (T)-spaced equalizer structure with 8 taps; the pre-equalizer MAY have 1, 2 or 4 samples per symbol, with a tap length longer than 8 symbols. In DOCS 1.1 mode, for backwards compatibility, the CMTS MAY support fractionally spaced equalizer format ( $T/2$  and  $T/4$ ). In DOCS 2.0 mode, the pre-equalizer MUST support a symbol (T)-spaced equalizer structure with 24 taps.
+
+In DOCS 1.x-only logical channels, the CM and the CMTS MUST use DOCS 1.1 mode.
+
+In DOCS 2.0-only logical channels, the CM and the CMTS MUST use DOCS 2.0 mode.
+
+In DOCS 1.x/2.0 mixed logical channels, the CM and the CMTS MUST use DOCS 1.1 mode from initial ranging until DOCS 2.0 is activated in the registration process (if it is activated), and MUST use DOCS 2.0 mode after DOCS 2.0 is activated.
+
+The RNG-RSP MAC message carries the CM transmit equalization information, and may instruct the CM to either convolve the equalizer coefficients or (in DOCS 2.0 mode only) load them directly (refer to clause 8.3.6.1, "Encodings"). When the CM is instructed to convolve the transmit equalizer
+
+coefficients, it MUST convolve the coefficients sent by the CMTS in the RNG-RSP with the existing coefficients to get the new coefficients. After convolving, the CM MUST truncate the convolution result such that 24 taps (8 taps in DOCS 1.1 mode) remain after the truncation, with the main tap located at the tap designated by the last RNG-RSP received by the CM. The operation of the convolution is formalized by the following equation:
+
+$$F_n^{m+1} = \sum_{k=\max(1-L^{m+1}, n+L^m-L^{m+1}-24)}^{\min(24-L^m-L^{m+1}-1)} F_{n-k+L^m-L^{m+1}}^m \cdot F_{k+L^{m+1}}, n=1 \dots 24$$
+
+where:
+
+$F_n^m$  are the coefficients prior to the convolution
+
+$F_n^{m+1}$  are the coefficients after the convolution
+
+$\hat{F}_n$  are the coefficients sent from the CMTS
+
+$L^m$  is the main tap location prior to the convolution
+
+$L^{m+1}$  is the main tap location after the convolution as dictated by the CMTS
+
+When the CM is instructed to load the transmit equalizer coefficients it MUST load the coefficients sent by the CMTS into the pre-equalizer coefficients after proper normalization, if necessary.
+
+In DOCS 1.x-only channels, in response to an initial ranging request and periodic ranging requests prior to CM registration, when the CMTS sends the pre-equalizer coefficients, the CMTS MUST compute and send them with an equalizer length of 8 and in T-spaced format, where T is the modulation interval. After registration, the CMTS MAY use a fractionally spaced equalizer format (T/2- or T/4-spaced) with a longer tap length to match the CM pre-equalizer capabilities that the CMTS learned from the REG-REQ message modem capabilities field. See clause 8.3.8.1.1 for proper use of the modem capabilities field.
+
+In DOCS 2.0-only channels, the CMTS MUST compute and send the pre-equalizer coefficients with an equalizer length of 24 and in T-spaced format at all times.
+
+In DOCS 1.x/2.0 mixed logical channels, in response to an initial ranging request and periodic ranging requests prior to CM registration, when the CMTS sends the pre-equalizer coefficients, the CMTS MUST compute and send them with an equalizer length of 8 and in T-spaced format. After registration, if the DOCS 1.1 mode is activated, the CMTS MAY use a fractionally spaced equalizer format (T/2- or T/4-spaced) with a longer tap length to match the CM pre-equalizer capabilities that the CMTS learned from the REG-REQ message modem capabilities field. If DOCS 2.0 is activated, the CMTS MUST use a T-spaced equalizer structure with 24 taps. If the first update of the pre-equalizer after the activation of DOCS 2.0 uses "convolve" mode, the CM MUST zero-pad the existing 8-tap filter to a 24-tap filter, and then convolve according to the rules above.
+
+Prior to making an initial ranging request and whenever the upstream channel frequency or upstream channel modulation rate changes, the CM MUST initialize the coefficients of the pre-equalizer to a default setting in which all coefficients are zero except the real coefficient of the first tap (i.e., F1). Whenever the main location is changed, the CM, not the CMTS, MUST compensate for the delay (ranging offset) due to a shift from the previous main tap location to a new main tap location of the equalizer coefficients sent by the CMTS (in both "convolve" and "load" operations). The pre-equalizer coefficients are then updated through the subsequent ranging process (unicast initial ranging and periodic ranging).
+
+In DOCS 1.1 mode, the CMTS MUST NOT move the main tap location during periodic ranging.
+
+In DOCS 1.1 mode, the CMTS MUST NOT instruct the CM to load the transmit equalizer coefficients.
+
+In DOCS 2.0 mode, the CMTS MAY move the main tap location during unicast initial ranging or periodic ranging.
+
+Equalizer coefficients may be included in every RNG-RSP message, but typically they only occur when the CMTS determines the channel response has significantly changed. The frequency of equalizer coefficient updates in the RNG-RSP message is determined by the CMTS.
+
+The CM MUST normalize the transmit equalizer coefficients in order to guarantee proper operation (such as not to overflow or clip). The CM MUST NOT change its target transmit power due to gain or loss of the new coefficients in both "convolve" and "load" operations. The target power is defined in clause 6.2.18.
+
+In DOCS 1.1 mode, if the CM equalizer structure implements the same number of coefficients as assigned in the RNG-RSP message, then the CM MUST NOT change the location of the main tap in the RNG-RSP message. If the CM equalizer structure implements a different number of coefficients than defined in the RNG-RSP message, the CM MAY shift the location of the main tap value. Again, in doing so, the CM MUST adjust its ranging offset, in addition to any adjustment in the RNG-RSP message, by an amount that compensates for the movement of the main tap location.
+
+### 6.2.16 Spectral shaping
+
+The upstream transmitter MUST approximate a Nyquist square-root raised-cosine pulse-shaping filter with roll-off factor  $\alpha = 0.25$ . The -30 dB transmitted bandwidth MUST NOT exceed the channel width values in Table 6-5. The channel width values are given analytically by:
+
+$$\text{ChannelWidth} = \text{ModulationRate} \times (1 + \alpha).$$
+
+**Table 6-5 – Maximum channel width**
+
+| Modulation rate (kHz) | Channel width (kHz) |
+|-----------------------|---------------------|
+| 160                   | 200                 |
+| 320                   | 400                 |
+| 640                   | 800                 |
+| 1280                  | 1600                |
+| 2560                  | 3200                |
+| 5120                  | 6400                |
+
+#### 6.2.16.1 Upstream frequency agility and range
+
+The upstream PMD sublayer MUST support operation over the frequency range of 5-42 MHz edge to edge.
+
+Offset frequency commands MUST be supported per Table 6-8.
+
+#### 6.2.16.2 Spectrum format
+
+The upstream modulator MUST provide operation with the format
+
+$$s(t) = I(t) \times \cos(\omega t) - Q(t) \times \sin(\omega t)$$
+
+where  $t$  denotes time and  $\omega$  denotes angular frequency.
+
+### 6.2.17 Relative processing delays
+
+The CM MAP processing delay is the time provided between arrival of the last bit of a MAP message at a CM and the effectiveness of this MAP. During this time, the CM should process the MAP message and fill its interleavers (or its framer, in S-CDMA mode) with encoded data. The CMTS MUST transmit the MAP message early enough to allow the CM MAP processing delay specified below.
+
+The CM MAP processing delay,  $D_p$ , is given by the equations:
+
+$$D_p = 200 + \frac{M}{5.12} \mu\text{s} ,$$
+
+$$M = \begin{cases} I_r N_r, & I_r \neq 0 \\ B_r, & I_r = 0 \end{cases}$$
+
+where  $M$  is the number of elements in the CM interleavers (in the case of TDMA), or framer (in the case of S-CDMA). In DOCS 1.x mode,  $M = 0$ . Note that in the above equations, the values for  $B_r$  and  $I_r \times N_r$  are taken to be the maximum from all of the specified burst types in a particular UCD.
+
+In S-CDMA mode,  $M = 128 (K+1)$ , where  $K$  is the number of spreading intervals per frame. This is the time required for processing an S-CDMA frame plus an extra spreading interval. For example in the case of  $K = 32$ , which corresponds to the maximum framer size, the CM MAP processing time is 1025  $\mu\text{s}$ , assuming a modulation rate of 5.12 MHz.
+
+NOTE 1 – The CM MAP processing delay does not include downstream FEC de-interleaving delay.
+
+NOTE 2 – The "effectiveness of the MAP" relates to the beginning of the burst frame at the RF output of the CM. In the S-CDMA mode, "effectiveness of the MAP" relates to the beginning (at the RF output of the CM) of the first spreading interval of the S-CDMA frame which contains the burst.
+
+### 6.2.18 Transmit power requirements
+
+The CM MUST support varying the amount of transmit power. Requirements are presented for:
+
+- 1) range of reported transmit power;
+- 2) step size of power commands;
+- 3) step size accuracy (actual change in output power compared to commanded change); and
+- 4) absolute accuracy of CM output power.
+
+The protocol by which power adjustments are performed is defined in clause 11.2.4. Such adjustments by the CM MUST be within the ranges of tolerances described below. A CM MUST confirm that the transmit power limits are met after a RNG-RSP is received or after a UCD change.
+
+Transmit power is defined as the average RF power in the occupied bandwidth (channel width) transmitted in the data symbols of a burst, assuming equally likely QAM symbols, measured at the F-connector of the CM. Maximum and minimum transmit power level requirements refer to the CM's target transmit power level, defined as the CM's estimate of its actual transmit power. The actual transmitted power MUST be within  $\pm 2$  dB of the target power. The target transmit power MUST be variable over the range specified in Table 6-8.
+
+Transmit power as reported by the CM in the MIB is referenced to the 64QAM constellation. When transmitting with other constellations, a slightly different transmit power will result, depending on the constellation gain in Table 6-6 (see clause 6.2.13). As an example, if the reported power is 30 dBmV, 64QAM will be transmitted with a target power of 30 dBmV, while QPSK will be transmitted with 28.82 dBmV.
+
+**Table 6-6 – Constellation gains and power limits**
+
+| Constellation | Constellation gain $G_{const}$ relative to 64QAM (dB) | $P_{min}$ (dBmV) | $P_{max}$ (dBmV) TDMA | $P_{max}$ (dBmV) S-CDMA | $P_{min}$ $G_{const}$ (dBmV) | $P_{max} - G_{const}$ (dBmV) TDMA | $P_{max} - G_{const}$ (dBmV) S-CDMA |
+|---------------|-------------------------------------------------------|------------------|-----------------------|-------------------------|------------------------------|-----------------------------------|-------------------------------------|
+| QPSK          | -1.18                                                 | 8                | 58                    | 53                      | 9.18                         | 59.18                             | 54.18                               |
+| 8QAM          | -0.21                                                 | 8                | 55                    | 53                      | 8.21                         | 55.21                             | 53.21                               |
+| 16QAM         | -0.21                                                 | 8                | 55                    | 53                      | 8.21                         | 55.21                             | 53.21                               |
+| 32QAM         | 0.00                                                  | 8                | 54                    | 53                      | 8.00                         | 54.00                             | 53.00                               |
+| 64QAM         | 0.00                                                  | 8                | 54                    | 53                      | 8.00                         | 54.00                             | 53.00                               |
+| 128QAM        | 0.05                                                  | 8                | N/A                   | 53                      | 7.95                         | N/A                               | 52.95                               |
+
+The actual transmitted power within a burst MUST be constant to within 0.1 dB peak to peak. This excludes the amplitude variation theoretically present due to QAM amplitude modulation, pulse shaping, pre-equalization, and for S-CDMA, spreading and varying number of allocated codes.
+
+The CM MUST support the transmit power calculations defined in clauses 6.2.18.1 and 6.2.18.2.
+
+#### 6.2.18.1 TDMA transmit power calculations
+
+In TDMA mode, the CM determines its target transmit power  $P_t$  as follows. Define:
+
+$P_r$  = Reported power level (dBmV) of CM in MIB (refers to 64QAM constellation)
+
+$\Delta P$  = Power level adjustment (dB); for example, as commanded in ranging response message
+
+$G_{const}$  = Constellation gain (dB) relative to 64QAM constellation (see above table)
+
+$P_{min}$  = Minimum target transmit power permitted for the CM per clause 6.2.21.1 (see Table 6-6)
+
+$P_{max}$  = Maximum target transmit power permitted for the CM per clause 6.2.21.1 (see Table 6-6)
+
+$P_{hi}$  =  $\min[P_{max} - G_{const}]$  over all burst profiles used by the CM (see Table 6-6)
+
+$P_{low}$  =  $\max[P_{min} - G_{const}]$  over all burst profiles used by the CM (see Table 6-6)
+
+$P_t$  = Target transmit power level (dBmV) of CM (actual transmitted power as estimated by CM)
+
+The CM updates its reported power by the following steps:
+
+- 1)  $P_r = P_r + \Delta P$  //Add power level adjustment to reported power level
+- 2)  $P_r = \min[P_r, P_{hi}]$  //Clip at max. power limit
+- 3)  $P_r = \max [P_r, P_{low}]$  //Clip at min. power limit
+
+The CM then transmits with target power  $P_t = P_r + G_{const}$ , i.e., the reported power plus the constellation gain.
+
+Usually, the reported power level is a relatively constant quantity, while the transmitted power level varies dynamically as different burst profiles, with different constellation gains, are transmitted. A CM's target transmit power MUST never be below  $P_{min}$  or above  $P_{max}$ . This implies that in some cases the extreme transmit power levels (e.g., 58 dBmV for QPSK and 8 dBmV) may not be permitted if burst profiles with multiple constellations are active. Also, if only QPSK is used, the reported power may be greater than 58 dBmV, although the target transmit power will not exceed 58 dBmV.
+
+For example, if only QPSK and 64QAM burst profiles are active,  $P_{hi} = 54$  dBmV and  $P_{low} = 9.2$  dBmV. The maximum permitted QPSK transmitted power is  $54 - 1.2 = 52.8$  dBmV, the minimum QPSK power is  $9.2 - 1.2 = 8$  dBmV, the maximum 64QAM power is 54 dBmV, and the minimum 64QAM power is 9.2 dBmV.
+
+#### 6.2.18.2 S-CDMA transmit power calculations
+
+In S-CDMA mode, the power calculations depend on whether the maximum scheduled codes feature is enabled.
+
+##### 6.2.18.2.1 S-CDMA transmit power calculations when maximum scheduled codes are not enabled
+
+In S-CDMA mode, when maximum scheduled codes are not enabled, the CM determines its target transmit power  $P_t$  as follows. Define:
+
+$$\begin{aligned} P_r &= \text{reported power level (dBmV) of CM in MIB (refers to 64QAM constellation and all active codes transmitted)} \\ P_{hi} &= \min[P_{max} - G_{const}] \text{ over all burst profiles used by the CM (see Table 6-6)} \\ P_{low} &= \max[P_{min} - G_{const}] + 10 \log(\text{number\_active\_codes/number\_of\_codes\_per\_mini-slot}) \text{ where the maximum is over all burst profiles used by the CM (see Table 6-6)} \end{aligned}$$
+
+The CM updates its reported power by the following steps:
+
+- 1)  $P_r = P_r + \Delta P$  //Add power level adjustment to reported power level
+- 2)  $P_r = \min[P_r, P_{hi}]$  //Clip at max. power limit
+- 3)  $P_r = \max[P_r, P_{low}]$  //Clip at min. power limit
+
+In a spreader-on frame, the CM then transmits each code  $i$  with target power:
+
+$$P_{t,i} = P_r + G_{const,i} - 10 \log(\text{number\_active\_codes})$$
+
+i.e., the reported power plus the constellation gain  $G_{const,i}$  of that code, less a factor taking into account the number of active codes. The total transmit power,  $P_t$ , in a frame is the sum of the individual transmit powers,  $P_{t,i}$ , of each code, where the sum is performed using absolute power quantities (non-dB domain).
+
+In a spreader-off frame, the CM target transmit power is:
+
+$$P_t = P_r + G_{const}$$
+
+The transmitted power level varies dynamically as the number of allocated codes varies, and as different burst profiles, with different constellation gains, are transmitted. A CM's target transmit power MUST never be below  $P_{min}$  or above  $P_{max}$ , including over all numbers of allocated codes and all burst profiles. This implies that in some cases the extreme transmit power levels (e.g., 8 and 53 dBmV) may not be permitted. Also if, for example, only QPSK is used, the reported power may be greater than 53 dBmV, although the target transmit power will not exceed 53 dBmV.
+
+If, for example, QPSK and 64QAM burst profiles are active, the number of active codes is 128 and the number of codes per mini-slot is 2, then  $P_{hi} = 53$  dBmV and  $P_{low} = 27.24$  dBmV. The maximum permitted QPSK transmitted power is  $53 - 1.18 = 51.82$  dBmV when all active codes are transmitted. The minimum QPSK power is  $27.24 - 1.18 - 10\log(128) + 10\log(2) = 8$  dBmV when one mini-slot is transmitted. The last term in the sum is the result of summing the individual powers over 2 codes. Similarly, the maximum 64QAM power is 53 dBmV when all active codes are transmitted, and the minimum 64QAM power is  $27.24 - 10\log(128) + 10\log(2) = 9.18$  dBmV when one mini-slot is transmitted. The minimum QPSK power permitted while transmitting, for example, 2 mini-slots is 11 dBmV, and the minimum 64QAM power permitted while transmitting 2 mini-slots is 12.2 dBmV.
+
+The CM needs to implement some form of clipping on the transmitted waveform at the higher output powers in order to prevent peak-to-average ratio (PAR) issues.
+
+The power received at the CMTS in a spreader-on frame will sometimes be less than the nominal power of a spreader-off frame because of such factors as:
+
+- 1) broadcast opportunities not used by any CM;
+- 2) unicast grants not used by one or more CMs; or
+- 3) mini-slots assigned to the NULL SID.
+
+##### 6.2.18.2.2 S-CDMA transmit power calculations when maximum scheduled codes are enabled
+
+In S-CDMA mode on channels on which maximum scheduled codes are enabled, the CM determines its target transmit power  $P_t$  as follows. Define:
+
+$P_r$  = reported power level (dBmV) of CM in MIB (operational transmit power of the spreader-off ranging burst referenced to 64QAM modulation)
+
+$P_{hi\_S}$  =  $\min[53 - G_{const}]$  over all spreader-on burst profiles used by the CM (see Table 6-6)
+
+$P_{low\_S}$  =  $\max[8 - G_{const}] + 10 \log(\text{number\_active\_codes}/\text{number\_of\_codes\_per\_mini-slot})$  where the maximum is over all burst profiles used by the CM (see Table 6-6)
+
+$P_{max\_T}$  = Maximum target transmit power permitted for the CM in TDMA mode (see Table 6-6) for the constellation used in ranging
+
+$P_{hi\_T}$  =  $\min[P_{max\_T} - G_{const}]$  over all spreader-off burst profiles used by the CM (see Table 6-6)
+
+$P_{on}$  =  $P_r$  clipped at the maximum spreader-on limit
+
+$P_{sf}$  = CM power shortfall per clauses 8.3.5 and 8.3.26
+
+$P_{hr}$  = S-CDMA power headroom in dB. Equivalent to TLV-11 defined in Table 8-21 divided by 4
+
+$\Delta P$  = power level adjustment in dB sent from CMTS to CM
+
+The CM updates its power by the following steps:
+
+1.  $P_r = P_r + \Delta P$  //Add power level adjustment to reported power level
+2.  $P_r = \min[P_r, P_{hi\_T}]$  //Clip at max. TDMA power limit
+3.  $P_r = \max[P_r, P_{low\_S}]$  //Clip at min. S-CDMA power limit
+4.  $P_{on} = \min[P_r, P_{hi\_S}]$  //Clip at max. S-CDMA power limit
+
+In spreader-off frames, the CM transmits with target power
+
+$$P_t = P_r + G_{const}$$
+
+Based on the spreader-off transmit power, the CM updates its power shortfall according to the following steps:
+
+$$P_{sf} = P_r + \max[G_{const,i}] - 53$$
+
+// Difference between spreader-off reported and max. spreader-on target powers
+
+$$P_{sf} = \max[P_{sf}, 0]$$
+
+// Set  $P_{sf}$  to 0 if  $P_t$  is less than 53 dBmV
+
+In spreader-on frames, the CM transmits each code  $i$  with target power
+
+$$P_{t,i} = P_{on} + G_{const,i} - 10 \log(\text{number\_active\_codes}) + P_{hr}$$
+
+i.e., the clipped reported power plus the constellation gain,  $G_{const, i}$ , of that code, less a factor taking into account the number of active codes, plus the power headroom,  $P_{hr}$ .  $P_{hr}$  is the power (in dB) added to account for CMs that have a maximum scheduled code limit and can transmit additional power per code. The total transmit power  $P_t$  in a frame is the sum of the individual transmit powers,  $P_{t, i}$ , of each code, where the sum is performed over all  $N_{alloc}$  allocated codes using absolute power quantities (non-dB domain).
+
+$$P_t = 10 \log \sum_{i=1}^{N_{alloc}} 10^{P_{t,i}/10}$$
+
+If, for example, the burst profile contains QPSK for IUCs 1,2,3 and 4 and 64QAM for IUCs 9 and 10, the number of active codes is 128, and the number of codes per mini-slot is 2, then  $P_{hi\_S} = 53$  dBmV,  $P_{low\_S} = 27.24$  dBmV, and  $P_{hi\_T} = 58$  dBmV. Assume the CM ranges at spreader-off target transmit power of 57 dBmV. The CM reports  $P_{sf} = 57$  dBmV – 53 dBmV = 4 dB. The CMTS uses  $P_{sf}$  to set (using its vendor-specific algorithm)  $max\_scheduled\_codes = 32$  and  $P_{hr} = 6$  dB (the S-CDMA power headroom may differ from the power shortfall, at the discretion of the CMTS). The CM sets its transmitted power per code to:
+
+$$\begin{aligned} P_{t,i} &= P_{on} + G_{const, i} - 10 \log(\text{number\_active\_codes}) + P_{hr} \\ &= 53 \text{ dBmV} + 0 \text{ dB} - 21 \text{ dB} + 6 \text{ dB} && // \text{ For a code with 64QAM modulation} \\ &= 38 \text{ dBmV} \end{aligned}$$
+
+A parameter that may be used to illustrate the effect of increased power per code is the effective transmit power,  $P_{eff}$ , the power that would result hypothetically if all  $N_{act}$  active codes were transmitted. It is computed as:
+
+$$\begin{aligned} P_{eff} &= 10 \log \sum_{i=1}^{N_{act}} 10^{P_{t,i}/10} \\ &= P_{on} + P_{hr} + 10 \log \frac{1}{N_{act}} \sum_{i=1}^{N_{act}} 10^{G_{const,i}/10} \end{aligned}$$
+
+where the last term is the average constellation gain.
+
+For a reference case with all codes transmitted using 64QAM modulation ( $G_{const} = 0$  dB), the effective transmit power reduces to:
+
+$$P_{eff} = P_{on} + P_{hr}$$
+
+Continuing the above example, the result is:
+
+$$\begin{aligned} P_{eff} &= 53 \text{ dBmV} + 6 \text{ dB} \\ &= 59 \text{ dBmV} \end{aligned}$$
+
+Limiting the number of codes has given the CM an enhanced effective power of 59 dBmV, which is 6 dB above the normal maximum of 53 dBmV, and 2 dB above the ranging power of 57 dBmV. In this example, the CMTS used its discretion to ask for 2 dB more enhancement than was needed ( $P_{hr} = 6$  dB vs  $P_{sf} = 4$  dB), perhaps due to some known impairment in the channel.
+
+The *effective\_SNR* is an SNR estimate for a given code corresponding to the effective transmit power. It is defined as the measured SNR at the last station maintenance, minus the CM power shortfall, plus the power headroom, plus the difference in constellation gain between the ranging burst and the code under consideration. Its equation is:
+
+$$effective\_SNR = measured\_SNR - P_{sf} + P_{hr} + (G_{const, i} - G_{const, ranging})$$
+
+where  $G_{const, ranging}$  is the constellation gain of the ranging burst that resulted in the SNR measurement. In the MIB, *effective\_SNR* corresponds to a reference case with 64QAM modulation ( $G_{const, i} = 0$  dB):
+
+$$effective\_SNR = measured\_SNR - P_{sf} + P_{hr} - G_{const, ranging}$$
+
+Continuing the example, if the measured SNR in the last station maintenance was 17 dB using QPSK modulation ( $G_{const, ranging} = -1.2$  dB) then the effective SNR referenced to 64QAM modulation is:
+
+$$effective\_SNR = 17 \text{ dB} - 4 \text{ dB} + 6 \text{ dB} + 1.2 \text{ dB} = 20.2 \text{ dB}$$
+
+#### 6.2.18.3 Transmit power step size
+
+The step resolution in transmit power MUST be 1 dB or less. When a CM is commanded with finer resolution than it can implement, it MUST round to the nearest supported step size. If the commanded step is halfway between two supported step sizes, the CM MUST choose the smaller step. For example, with a supported step resolution of 1 dB, a command to step  $\pm 0.5$  dB would result in no step, while a command to step  $\pm 0.75$  dB would result in a  $\pm 1$  dB step.
+
+The step size accuracy MUST be within  $\pm 0.4$  dB. For example, the actual power increase resulting from a command to increase the power level by 1 dB in a CM's next transmitted burst MUST be between 0.6 dB and 1.4 dB.
+
+A relaxation in step size accuracy to  $\pm 1.4$  dB is allowed for one gain change when changing the power throughout the full power control range in either direction (from low-end to high-end power and vice versa). The locations of these two gain changes with relaxed accuracy MUST be at least 2 dB apart, thus enabling the use of large step attenuators in the coverage of the full power control range (hysteresis effect).
+
+### 6.2.19 Burst profiles
+
+The transmission characteristics are separated into three portions:
+
+- a) channel parameters;
+- b) burst profile attributes; and
+- c) user-unique parameters.
+
+The channel parameters include:
+
+- i) the modulation rate (six rates from 160 ksymb/s to 5.12 Msymb/s in octave steps);
+- ii) the centre frequency (Hz);
+- iii) the 1536-bit preamble superstring; and
+- iv) the S-CDMA channel parameters.
+
+The channel parameters are further described in Table 8-18; these characteristics are shared by all users on a given channel. The burst profile attributes are listed in Table 6-7, and are further described in Table 8-19; these parameters are the shared attributes corresponding to a burst type.
+
+The CM MUST generate each burst at the appropriate time as conveyed in the mini-slot grants provided by the CMTS MAPs (see clause 8.3.4).
+
+The CM MUST support all burst profiles commanded by the CMTS via the burst descriptors in the UCD (see clause 8.3.3), and subsequently assigned for transmission in a MAP (see clause 8.3.4).
+
+**Table 6-7 – Burst profile attributes**
+
+| <b>Burst profile attributes</b>                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | <b>Configuration settings</b>                                                        |
+|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------|
+| Modulation                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | QPSK, 8QAM, 16QAM, 32QAM, 64QAM, 128QAM (TCM only)                                   |
+| Differential encoding                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | On/off                                                                               |
+| TCM encoding                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | On/off                                                                               |
+| Preamble length                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 0-1536 bits (see clause 6.2.9)                                                       |
+| Preamble value offset                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | 0 to 1534                                                                            |
+| R-S FEC error correction (T)                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | 0 to 16 (0 implies no R-S FEC. The number of codeword parity bytes is $2 \times T$ ) |
+| R-S FEC codeword information bytes (k)                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | Fixed: 16 to 253 (assuming R-S FEC on)<br>Shortened: 16 to 253 (assuming R-S FEC on) |
+| Scrambler seed                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 15 bits                                                                              |
+| Maximum burst length (mini-slots) <sup>a)</sup>                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 0 to 255                                                                             |
+| Guard time                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 4 to 255 modulation intervals<br>There is no guard time in S-CDMA channels           |
+| Last codeword length                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | Fixed, shortened                                                                     |
+| Scrambler on/off                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | On/off                                                                               |
+| Byte interleaver depth ( $I_r$ ) <sup>b)</sup>                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 0 to floor ( $2048/N_r$ ) <sup>c)</sup>                                              |
+| Byte interleaver block size ( $B_r$ ) <sup>d)</sup>                                                                                                                                                                                                                                                                                                                                                                                                                                                        | $2 \times N_r$ to 2048                                                               |
+| Preamble type                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | QPSK0/QPSK1                                                                          |
+| S-CDMA spreader <sup>e)</sup>                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | On/off                                                                               |
+| S-CDMA codes per subframe <sup>e)</sup>                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | 1 to 128                                                                             |
+| S-CDMA interleaver step <sup>e)</sup>                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | 1 to (spreading intervals per frame – 1)                                             |
+| <sup>a)</sup> A burst length of 0 mini-slots in the channel profile means that the burst length is variable on that channel for that burst type. The burst length, while not fixed, is granted explicitly by the CMTS to the CM in the MAP.<br><sup>b)</sup> If depth = 1, no interleaving; if depth = 0, dynamic mode.<br><sup>c)</sup> $N_r$ is the R-S codeword size $k + 2T$ as defined in clause 6.2.6.1.<br><sup>d)</sup> Used only in dynamic mode.<br><sup>e)</sup> Used only for S-CDMA channels. |                                                                                      |
+
+The user-unique parameters may vary for each user even when using the same burst type on the same channel as another user (for example, power level), and are listed in Table 6-8.
+
+**Table 6-8 – User-unique burst parameters**
+
+| User-unique parameter                                                          | Adjustment command                                                                                                                                                                                                                                         | Resulting parameter value                                                                                                                                                                                |
+|--------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Power level                                                                    | 8-bit two's complement, resolution = 0.25 dB                                                                                                                                                                                                               | TDMA:<br>+8 to +54 dBmV (32QAM, 64QAM)<br>+8 to +55 dBmV (8QAM, 16QAM)<br>+8 to +58 dBmV (QPSK)<br>S-CDMA:<br>+8 to +53 dBmV (all modulations)<br>Resolution = 1 dB or better                            |
+| Offset frequency                                                               | Range = 32 kHz, resolution = 1 Hz                                                                                                                                                                                                                          | Range = $\pm 32$ kHz; increment = 1 Hz; implement within $\pm 10$ kHz                                                                                                                                    |
+| Ranging offset                                                                 | Integer part: 32-bit two's complement, resolution = $(1/10.24 \text{ MHz}) = 6.25 \mu\text{s}/64 = 97.65625 \text{ ns}$<br><br>Fractional part: unsigned 8-bit fractional extension, resolution = $6.25 \mu\text{s}/(64*256) = 0.3814697265625 \text{ ns}$ | Integer part: 0 to $(2^{16} - 1)$ , increments of $6.25 \mu\text{s}/64$<br><br>Fractional part: Unsigned 8-bit fractional extension, units of $6.25 \mu\text{s}/(64 \times 256) = 0.38146973 \text{ ns}$ |
+| Burst length (mini-slots) if variable on this channel (changes burst-to-burst) | N/A                                                                                                                                                                                                                                                        | 1 to 255 mini-slots                                                                                                                                                                                      |
+| Transmit equalizer coefficients                                                | DOCSIS 2.0 mode: 24 complex coefficients, 4 bytes per coefficient (2 real and 2 imaginary), load and convolve modes<br><br>DOCSIS 1.1 mode: up to 64 complex coefficients, 4 bytes per coefficient (2 real and 2 imaginary), convolve mode only            | Up to 64 coefficients; 4 bytes per coefficient: 2 real and 2 imaginary                                                                                                                                   |
+
+The CM MUST implement the offset frequency adjustment to effect a change in upstream carrier frequency within 10 Hz of the commanded change.
+
+#### 6.2.19.1 Ranging offset
+
+Ranging offset is the time difference between the CM upstream frame time base and the CMTS upstream frame time base. It is an advancement equal to roughly the round-trip delay of the CM from the CMTS, and is needed to synchronize upstream transmissions in the TDMA and S-CDMA schemes. The CMTS MUST provide the CM with feedback adjustments of this offset, based on reception of one or more successfully received bursts (i.e., satisfactory result from each technique employed: Error correction and/or CRC). The CMTS sends these timing adjust commands to the CM in the ranging response MAC message (see clause 8.3.6), where a negative value implies the ranging offset is to be decreased, resulting in later times of transmission at the CM.
+
+For TDMA channels, the CM MUST implement the timing adjust command with resolution of at most one symbol duration (of the symbol rate in use for a given burst) and (other than a fixed bias) with accuracy within  $\pm 0.25 \mu\text{s}$  plus  $\pm 1/2$  symbol owing to resolution. As an example, for the maximum symbol rate of 5120 ksymb/s, the corresponding symbol period would be 195 ns, the
+
+corresponding maximum resolution for the timing adjustment MUST be 195 ns, and the corresponding minimum accuracy MUST be  $\pm 348$  ns. The accuracy of CM burst timing of  $\pm 0.25$   $\mu\text{s}$  plus  $\pm 1/2$  symbol is relative to the mini-slot boundaries derivable at the CM based on an ideal processing of the timestamp signals received from the CMTS.
+
+The resolution of the integer part of the timing adjust parameter, which is used for TDMA channels, is  $(1/10.24 \text{ MHz}) = 6.25 \mu\text{s}/64 \approx 97.66 \text{ ns}$ . For S-CDMA channels the CM MUST implement the timing adjust to within  $\pm 0.01$  of the nominal chip period. As an example, for the maximum chip rate of 5120 ksymb/s, the corresponding maximum resolution for the timing correction would be  $195 \text{ ns} \times (\pm 0.01)$ , or roughly  $\pm 2 \text{ ns}$ .
+
+#### 6.2.19.2 TDMA reconfiguration times
+
+The CM MUST be capable of switching burst profiles with no reconfiguration time required between bursts except for changes in the following parameters:
+
+- 1) output power;
+- 2) symbol rate;
+- 3) offset frequency;
+- 4) channel frequency; and
+- 5) ranging offset.
+
+For **output power** changes: If output power is to be changed by 1 dB or less, the CM MUST be able to implement the change between bursts as long as the CMTS allocates at least 96 symbols plus 5  $\mu\text{s}$  between the last symbol centre of one burst and the first symbol centre of the following burst. If output power is to be changed by more than 1 dB, the CM MUST be able to implement the change between bursts as long as the CMTS allocates at least 96 symbols plus 10  $\mu\text{s}$  between the last symbol centre of one burst and the first symbol centre of the following burst. The maximum reconfiguration time of 96 symbols should compensate for the ramp-down time of one burst and the ramp-up time of the next burst as well as the overall transmitter delay time including the pipeline delay and optional pre-equalizer delay. The output power of the CM MUST be settled to within  $\pm 0.1$  dB of its final output power level:
+
+- a) within 5  $\mu\text{s}$  from the beginning of a change of 1 dB or less; and
+- b) within 10  $\mu\text{s}$  from the beginning of a change of greater than 1 dB. Output power MUST NOT be changed until the CM is provided sufficient time between bursts by the CMTS, and MUST NOT change while more than  $-30$  dB of any symbol's energy of the previous burst remains to be transmitted, or more than  $-30$  dB of any symbol's energy of the next burst has been transmitted.
+
+For **symbol rate** changes, the CM MUST be able to transmit consecutive bursts as long as the CMTS allows the required time between bursts for UCD parameter changes (see clause 11.3.2, "Changing upstream channel descriptor message parameters"). Symbol rate MUST NOT be changed until the CM is provided sufficient time between bursts by the CMTS, and MUST NOT change while more than  $-30$  dB of any symbol's energy of the previous burst remains to be transmitted, or more than  $-30$  dB of any symbol's energy of the next burst has been transmitted.
+
+For **offset frequency** changes, the CM MUST be able to transmit consecutive bursts as long as the CMTS allocates at least 96 symbols in between the last symbol centre of one burst and the first symbol centre of the following burst. The maximum reconfiguration time of 96 symbols should compensate for the ramp-down time of one burst and the ramp-up time of the next burst as well as the overall transmitter delay time including the pipeline delay and optional pre-equalizer delay. Offset frequency MUST NOT be changed until the CM is provided sufficient time between bursts by the CMTS, and MUST NOT change while more than  $-30$  dB of any symbol's energy of the
+
+previous burst remains to be transmitted, or more than  $-30$  dB of any symbol's energy of the next burst has been transmitted.
+
+For **channel frequency** changes, the CM MUST be able to implement the change between bursts as long as the CMTS allocates at least 96 symbols plus 100 ms between the last symbol centre of one burst and the first symbol of the following burst. The channel frequency of the CM MUST be settled within the phase noise and accuracy requirements of clauses 6.2.21.5 and 6.2.21.6 within 100 ms from the beginning of the change. Channel frequency MUST NOT be changed until the CM is provided sufficient time between bursts by the CMTS, and MUST NOT change while more than  $-30$  dB of any symbol's energy of the previous burst remains to be transmitted, or more than  $-30$  dB of any symbol's energy of the next burst has been transmitted.
+
+For **ranging offset** changes, the CM MUST be able to transmit consecutive bursts as long as the CMTS allocates at least 96 symbols in between the last symbol centre of one burst and the first symbol centre of the following burst. The maximum reconfiguration time of 96 symbols should compensate for the ramp-down time of one burst and the ramp-up time of the next burst as well as the overall transmitter delay time including the pipeline delay and optional pre-equalizer delay. Ranging offset MUST NOT be changed until the CM is provided sufficient time between bursts by the CMTS, and MUST NOT change while more than  $-30$  dB of any symbol's energy of the previous burst remains to be transmitted, or more than  $-30$  dB of any symbol's energy of the next burst has been transmitted.
+
+For modulation type changes, the CM MUST be able to transmit consecutive bursts with no reconfiguration time between them (except for the minimum guard time). The modulation MUST NOT change while more than  $-30$  dB of any symbol's energy of the previous burst remains to be transmitted, or more than  $-30$  dB of any symbol's energy of the next burst has been transmitted, EXCLUDING the effect of the transmit equalizer (if present in the CM) (this is to be verified with the transmit equalizer providing no filtering; delay only, if that. Note that if the CMTS has decision feedback in its equalizer, it may need to provide more than the 96-symbol gap between bursts of different modulation type, which the same CM may use; this is a CMTS decision).
+
+#### 6.2.19.3 S-CDMA reconfiguration times
+
+In S-CDMA mode, for changes in output power per mini-slot, offset frequency, pre-equalizer coefficients, and/or ranging offset, the CM MUST be able to transmit consecutive bursts as long as the CMTS allocates the time duration of at least one frame in between the bursts. For all other burst profile parameter changes, no reconfiguration is required beyond what is provided by the MAC for such changes.
+
+#### 6.2.19.4 CM timing offsets when changing modulation rate
+
+When making a modulation rate change, the CM MUST employ the following timing offsets when changing modulation rates. The offsets in the table correspond to the contribution of DOCSIS 1.0 and 1.1 legacy upstream receivers to changes in latency when making modulation rate changes. These offsets are maintained into DOCSIS 2.0 but with the addition of including in the table the highest modulation rate. The timing offset to apply is the difference between the entry in the table corresponding to the new modulation rate and the entry corresponding to the original modulation rate. The offsets are referenced to the centre of the first symbol in the burst, which is the reference point for burst timing as stated in clause 6.2.20. Specification of these offsets is needed so that CMs apply uniform adjustments to their ranging offsets and so that CMTSs can appropriately handle CMs that apply these offsets when making modulation rate changes.
+
+| Modulation rate | Timing offset (in units of 1/64 time ticks referenced to 5.12 MHz) |
+|-----------------|--------------------------------------------------------------------|
+| 5.12 MHz        | 0 (reference)                                                      |
+| 2.56 MHz        | 0                                                                  |
+| 1.28 MHz        | 24                                                                 |
+| 0.64 MHz        | 72                                                                 |
+| 0.32 MHz        | 168                                                                |
+| 0.16 MHz        | 360                                                                |
+
+As an example, suppose a CM is on an upstream channel operating at a modulation rate of 1.28 MHz. Now, suppose the UCD message from the CMTS changes the modulation rate of the channel to 0.32 MHz. The CM applies an additional timing offset of  $168 - 24 = 144$  to its ranging offset to compensate for this modulation rate change. The value of 144 is positive, and thus, the CM will add to its ranging offset so that it effectively transmits earlier by 144 units of 1/64 time ticks.
+
+Furthermore, in changing modulation rates, if a CM has its own contribution to a change in latency, the CM MUST also compensate for this CM-specific latency difference. This is in addition to the offset applied from the values in the table above, which result from legacy CMTS upstream receiver contributions to changes in latency. The requirements for CM burst timing accuracy found earlier in this clause for TDMA mode, referenced to the modulation rate that is the lower of the original and the new modulation rate, apply after the modulation rate change, with the required timing offsets above considered. Specifically, the CM MUST implement the timing adjustments with accuracy within 0.25 s plus 1/2 symbol, in both TDMA and S-CDMA modes. A CMTS that does not apply the same internal physical delay offsets as the legacy DOCSIS upstream CMTS receiver implementation is capable of receiving a CM burst after a modulation rate change in any of the following ways but is not limited necessarily to only these ways:
+
+- a) The CMTS may implement the internal physical delay offset, as specified in the above table.
+- b) The CMTS may implement an internal timing compensation based on the expected offset in the above table.
+- c) The CMTS may increase the guard time.
+- d) The CMTS may send an unsolicited RNG-RSP to each CM to adjust the delay offset. As discussed in clause 6.3.6, the CM is expected to be capable of adjusting its timing offset at any time with the accuracy specified within this clause.
+
+### 6.2.20 Burst timing convention
+
+Figure 6-29 illustrates the nominal burst timing for TDMA channels.
+
+a) Nominal burst profile (no timing errors); 8-symbol guard band is illustrated; 10-symbol ramp-up and ramp-down is illustrated.
+
+![Diagram of nominal TDMA burst timing showing two bursts, N and N+1, with their respective preamble, data, and parity symbols, and the timing reference points.](4619c14be962e4c3ba6613aad97f7a86_img.jpg)
+
+The diagram illustrates the nominal TDMA burst timing for two consecutive bursts, Burst N and Burst N+1. Each burst consists of a 10-symbol ramp-up, a preamble, data symbols, and a last FEC parity symbol, followed by a 10-symbol ramp-down. The timing is referenced to the symbol centre of the first symbol of each burst, which also serves as the mini-slot boundary.
+
+Key features of the diagram include:
+
+- Burst N:** Shows the first burst. Labels include "Ramp-up", "Preamble first symbol", "Preamble last symbol", "Data first symbol", and "Last FEC parity symbol".
+- Burst N+1:** Shows the second burst. Labels include "Ramp-down" (from Burst N), "10 symbols" (ramp-down duration), "8 symbols" (guard band duration), "Mini-slot boundary" (at the start of Burst N+1), and "Preamble first symbol" (at the start of Burst N+1).
+- Timing Reference:** A note indicates that timing is referenced to the symbol centre of the first symbol of each burst. A label "Centre of preamble First symbol = Mini-slot boundary" points to the start of Burst N+1.
+- Guard Band:** An 8-symbol guard band is shown between the end of Burst N and the start of Burst N+1.
+- Diagram Code:** J.122\_F6-29 is shown in the bottom right corner.
+
+Diagram of nominal TDMA burst timing showing two bursts, N and N+1, with their respective preamble, data, and parity symbols, and the timing reference points.
+
+NOTE - Ramp-down of one burst can overlap ramp-up of following burst even with one transmitter assigned both bursts.
+
+**Figure 6-29 – Nominal TDMA burst timing**
+
+Figure 6-30 indicates worst-case burst timing for a TDMA channel. In this example, burst N arrives 1.5 symbols late, and burst N + 1 arrives 1.5 symbols early, but separation of 5 symbols is maintained; 8-symbol guard band shown.
+
+![Figure 6-30 – Worst-case TDMA burst timing diagram. The diagram shows two bursts, Burst N and Burst N+1, on a timeline. Burst N is shown with a ramp-down tail, and Burst N+1 is shown with a ramp-up head. The diagram indicates the timing relationship between the last symbol of Burst N and the first symbol of Burst N+1. Key timing parameters shown include: 'Worst-case burst timing input to CMTS' at the top; 'Burst N' and 'Burst N + 1' labels; 'Time equal to 5 symbols separates the first symbol centre of burst N + 1 and the last symbol centre of burst N'; 'Symbol centre of Burst N, last symbol; 1.5 symbols late'; 'Symbol centre of Burst N + 1, last symbol; 1.5 symbols early'; '8-symbol guardband' between the end of Burst N and the start of Burst N+1; '1.5' symbol durations at the ends of the guardband; '5 symbols' duration for the main part of the guardband; and 'Mini-slot boundary' indicated by a vertical line.](b9745e4d501fcfe72053e7211ab39fed_img.jpg)
+
+Figure 6-30 – Worst-case TDMA burst timing diagram. The diagram shows two bursts, Burst N and Burst N+1, on a timeline. Burst N is shown with a ramp-down tail, and Burst N+1 is shown with a ramp-up head. The diagram indicates the timing relationship between the last symbol of Burst N and the first symbol of Burst N+1. Key timing parameters shown include: 'Worst-case burst timing input to CMTS' at the top; 'Burst N' and 'Burst N + 1' labels; 'Time equal to 5 symbols separates the first symbol centre of burst N + 1 and the last symbol centre of burst N'; 'Symbol centre of Burst N, last symbol; 1.5 symbols late'; 'Symbol centre of Burst N + 1, last symbol; 1.5 symbols early'; '8-symbol guardband' between the end of Burst N and the start of Burst N+1; '1.5' symbol durations at the ends of the guardband; '5 symbols' duration for the main part of the guardband; and 'Mini-slot boundary' indicated by a vertical line.
+
+**Figure 6-30 – Worst-case TDMA burst timing**
+
+At a symbol rate of  $R_s$ , symbols occur at a rate of one each  $T_s = 1/R_s$  seconds. Ramp-up and Ramp-down are the spread of a symbol in the time domain beyond  $T_s$  duration owing to the symbol-shaping filter and any residual effect from the transmit equalizer. If only one symbol were transmitted, its duration would be longer than  $T_s$  due to the shaping filter impulse response being longer than  $T_s$ . The spread of the first and last symbols of a burst transmission effectively extends the duration of the burst to longer than  $N \times T_s$ , where  $N$  is the number of symbols in the burst.
+
+For S-CDMA channels, the bursts from all CMs are synchronized. This means that the ramp-down of one burst may occur at the same time as the ramp-up of the subsequent burst. The CM MUST meet the ranging and synchronization requirements of S-CDMA to assure that the ramp-down and ramp-up of bursts are aligned.
+
+### 6.2.21 Fidelity requirements
+
+The following requirements assume that any pre-equalization is disabled unless otherwise noted.
+
+#### 6.2.21.1 Spurious emissions
+
+The spurious emissions specifications are separated into two regions based on the transmit power. Region 1 is defined to have a power range of +14 dBmV to  $(P_{max} - 3)$ , i.e., the central region. Region 2 is defined from +8 dBmV to +14 dBmV and  $(P_{max} - 3)$  to  $P_{max}$ , i.e., the low and high ends of the transmit power.  $P_{max}$  is defined in Table 6-8.
+
+For S-CDMA mode, when a modem is transmitting fewer than 4 spreading codes, the region 2 specifications are used for all transmit power levels. Otherwise, for all other numbers of spreading codes (e.g., 4 to 128) or for TDMA mode, the spurious emissions specifications are used according to the power ranges defined for regions 1 and 2 above.
+
+In addition, for S-CDMA, the spurious emission specifications for S-CDMA MUST be met for any *number\_allocated\_codes*, as defined in clause 6.2.19.
+
+The noise and spurious power MUST NOT exceed the levels given in Tables 6-9, 6-10 and 6-11.
+
+In Table 6-9, inband spurious includes noise, carrier leakage, clock lines, synthesizer spurious products, and other undesired transmitter products. It does not include ISI. The measurement bandwidth for inband spurious is equal to the modulation rate (e.g., 160 to 5120 kHz). All requirements expressed in dBc are relative to the actual transmit power that the CM emits.
+
+**Table 6-9 – Spurious emissions**
+
+| Parameter                                                                                              | Transmitting burst                                                                                                                                       | Between bursts                               |
+|--------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------|
+| Inband                                                                                                 | –40 dBc                                                                                                                                                  | The greater of –72 dBc or –59 dBmV           |
+| Adjacent band                                                                                          | See Table 6-10.                                                                                                                                          | The greater of –72 dBc or –59 dBmV           |
+| 3 or fewer carrier-related frequency bands (such as second harmonic, if <42 MHz)                       | Region 1: –50 dBc for transmitted modulation rate = 320 ksymb/s and above;<br>–47 dBc for transmitted modulation rate = 160 ksymb/s<br>Region 2: –47 dBc | The greater of –72 dBc or –59 dBmV           |
+| Bands within 5 to 42 MHz (excluding assigned channel, adjacent channels, and carrier-related channels) | See Table 6-11.                                                                                                                                          | The greater of –72 dBc or –59 dBmV           |
+| CM integrated spurious emissions limits (all in 4 MHz, includes discretes) <sup>a)</sup>               |                                                                                                                                                          |                                              |
+| 42 to 54 MHz                                                                                           | Max(–40 dBc, –26 dBmV)                                                                                                                                   | –26 dBmV                                     |
+| 54 to 60 MHz                                                                                           | –35 dBmV                                                                                                                                                 | –40 dBmV                                     |
+| 60 to 88 MHz                                                                                           | –40 dBmV                                                                                                                                                 | –40 dBmV                                     |
+| 88 to 860 MHz                                                                                          | –45 dBmV                                                                                                                                                 | Max(–45 dBmV, –40 dB ref d/s <sup>b)</sup> ) |
+| CM discrete spurious emissions limits                                                                  |                                                                                                                                                          |                                              |
+| 42 to 54 MHz                                                                                           | Max(–50 dBc, –36 dBmV)                                                                                                                                   | –36 dBmV                                     |
+| 54 to 88 MHz                                                                                           | –50 dBmV                                                                                                                                                 | –50 dBmV                                     |
+| 88 to 860 MHz                                                                                          | –50 dBmV                                                                                                                                                 | –50 dBmV                                     |
+
+<sup>a)</sup> These spec limits exclude a single discrete spur related to the tuned received channel; this single discrete spur MUST be no greater than –40 dBmV.
+
+<sup>b)</sup> "dB ref d/s" is relative to the received downstream signal level. Some spurious outputs are proportional to the receive signal level.
+
+The measurement bandwidth for the three (or fewer) carrier-related frequency bands (below 42 MHz) is 160 kHz, with up to three 160 kHz bands, each with no more than the value given in Table 6-9, allowed to be excluded from the "bands within 5 to 42 MHz transmitting burst" specifications of Table 6-11. Carrier-related spurious emissions include all products whose
+
+frequency is a function of the carrier frequency of the upstream transmission such as, but not limited to, carrier harmonics.
+
+The measurement bandwidth is also 160 kHz for the between bursts specifications of Table 6-9 below 42 MHz.
+
+The transmitting burst specifications apply during the mini-slots granted to the CM (when the CM uses all or a portion of the grant), and for 32 modulation intervals before and after the granted mini-slots. The between bursts specifications apply except during a used grant of mini-slots, and the 32 modulation intervals before and after the used grant.
+
+In TDMA mode, a mini-slot may be as short as 32 modulation intervals, or 6.25 microseconds at the 5120 ksymb/s rate, or as short as 200 microseconds at the 160 ksymb/s rate.
+
+##### 6.2.21.1.1 Adjacent channel spurious emissions
+
+Spurious emissions from a transmitted carrier may occur in an adjacent channel which could be occupied by a carrier of the same or different modulation rate. Table 6-10 lists the required adjacent channel spurious emission levels for all combinations of transmitted carrier modulation rates and adjacent channel modulation rates. The measurement is performed in an adjacent channel interval that is of appropriate bandwidth and distance from the transmitted carrier based on the modulation rates of the transmitted carrier and the carrier in the adjacent channel.
+
+**Table 6-10 – Adjacent channel spurious emissions relative to the transmitted burst power level**
+
+| Transmitted carrier modulation rate | Specification in the interval, region 1 | Specification in the interval, region 2 | Measurement interval and distance from carrier edge | Adjacent channel carrier modulation rate |
+|-------------------------------------|-----------------------------------------|-----------------------------------------|-----------------------------------------------------|------------------------------------------|
+| All modulation rates                | –47 dBc                                 | –45 dBc                                 | 20 kHz to 180 kHz                                   | 160 kHz                                  |
+|                                     | –47 dBc                                 | –45 dBc                                 | 40 kHz to 360 kHz                                   | 320 kHz                                  |
+|                                     | –46 dBc                                 | –45 dBc                                 | 80 kHz to 720 kHz                                   | 640 kHz                                  |
+|                                     | –45 dBc                                 | –44 dBc                                 | 160 kHz to 1440 kHz                                 | 1280 kHz                                 |
+|                                     | –44 dBc                                 | –41 dBc                                 | 320 kHz to 2880 kHz                                 | 2560 kHz                                 |
+|                                     | –42 dBc                                 | –38 dBc                                 | 640 kHz to 5760 kHz                                 | 5120 kHz                                 |
+
+##### 6.2.21.1.2 Spurious emissions in 5 to 42 MHz
+
+Spurious emissions, other than those in an adjacent channel or carrier-related emissions listed above, may occur in intervals (frequency bands) that could be occupied by other carriers of the same or different modulation rates. To accommodate these different modulation rates and associated bandwidths, the spurious emissions are measured in an interval equal to the bandwidth corresponding to the modulation rate of the carrier that could be transmitted in that interval. This interval is independent of the current transmitted modulation rate.
+
+Table 6-11 lists the possible modulation rates that could be transmitted in an interval, the required spurious level in that interval, and the initial measurement interval at which to start measuring the spurious emissions. Measurements should start at the initial distance and be repeated at increasing distance from the carrier until the upstream band edge, 5 MHz or 42 MHz, is reached. Measurement intervals should not include the three or fewer carrier-related emission bands excluded above.
+
+**Table 6-11 – Spurious emissions in 5 to 42 MHz relative to the transmitted burst power level**
+
+| Possible modulation rate in this interval | Specification in the interval, region 1 | Specification in the interval, region 2 | Initial measurement interval and distance from carrier edge |
+|-------------------------------------------|-----------------------------------------|-----------------------------------------|-------------------------------------------------------------|
+| 160 kHz                                   | –54 dBc                                 | –53 dBc                                 | 220 kHz to 380 kHz                                          |
+| 320 kHz                                   | –52 dBc                                 | –50 dBc                                 | 240 kHz to 560 kHz                                          |
+| 640 kHz                                   | –50 dBc                                 | –47 dBc                                 | 280 kHz to 920 kHz                                          |
+| 1280 kHz                                  | –48 dBc                                 | –44 dBc                                 | 360 kHz to 1640 kHz                                         |
+| 2560 kHz                                  | –46 dBc                                 | –41 dBc                                 | 520 kHz to 3080 kHz                                         |
+| 5120 kHz                                  | –44 dBc                                 | –38 dBc                                 | 840 kHz to 5960 kHz                                         |
+
+#### 6.2.21.2 Spurious emissions during burst on/off transients
+
+Each transmitter MUST control spurious emissions, prior to and during ramp-up and during and following ramp-down, before and after a burst.
+
+On/off spurious emissions, such as the change in voltage at the upstream transmitter output due to enabling or disabling transmission, MUST be no more than 100 mV, and such a step MUST be dissipated no faster than 2  $\mu\text{s}$  of constant slewing. This requirement applies when the CM is transmitting at +55 dBmV or more; at backed-off transmit levels, the maximum change in voltage MUST decrease by a factor of 2 for each 6-dB decrease of power level from +55 dBmV, down to a maximum change of 7 mV at 31 dBmV and below. This requirement does not apply to CM power-on and power-off transients.
+
+#### 6.2.21.3 Modulation error ratio (MER)
+
+MER measures the cluster variance caused by the transmit waveform. It includes the effects of ISI, spurious, phase noise and all other transmitter degradations.
+
+##### 6.2.21.3.1 Definitions
+
+**Symbol MER ( $\text{MER}_{\text{symb}}$ ):**  $\text{MER}_{\text{symb}}$  is defined as follows for TDMA or S-CDMA symbols. The transmitted RF waveform (after appropriate downconversion) is applied to the ideal receive symbol matched filter and is sampled once per symbol. For TDMA, the matched filter is a square-root raised cosine filter with  $\alpha = 0.25$ . For S-CDMA, the matched filter is a square-root raised cosine filter with  $\alpha = 0.25$ , convolved with the time-reversed spreading code sequence (in this convolution, the spreading code sequence is expressed as a weighted impulse train spaced at the chip period). No external noise (AWGN) is added to the signal. The carrier frequency offset, carrier phase offset, symbol timing and gain may be adjusted during each burst to maximize  $\text{MER}_{\text{symb}}$ . Equalization of the received waveform is not permitted. For cases where the CM transmit equalizer is ON, the transmit equalizer coefficients may be adjusted to maximize  $\text{MER}_{\text{symb}}$ .  $\text{MER}_{\text{symb}}$  is defined at the F connector of the CM, except that when an echo channel is inserted,  $\text{MER}_{\text{symb}}$  is defined at the output of the echo channel.  $\text{MER}_{\text{symb}}$  is computed by the formula:
+
+$$\text{MER}_{\text{symb}}(\text{dB}) = 10 \times \log_{10} \left( \frac{E_{av}}{\frac{1}{N} \sum_{j=1}^N |e_j|^2} \right)$$
+
+where:
+
+$E_{av}$  is the average constellation energy for equally likely symbols (see clause 6.2.13 and Figure 6-18)
+
+$N$  is the number of symbols averaged
+
+$e_j$  is the error vector from the  $j$ th received symbol to the ideal transmitted QAM symbol on the grid of Figure 6-18
+
+For S-CDMA,  $MER_{symb}$  is averaged over all active codes.
+
+***MER of composite chips (MER<sub>chip</sub>)***:  $MER_{chip}$  is specified for composite S-CDMA chips to ensure that high SNR is maintained, especially for a small number of allocated codes, to prevent noise funnelling effects when many modems transmit simultaneously. A composite S-CDMA chip is defined as the output of the spreader during one chip interval, that is, an element of the transmission vector  $\overline{P}_k$  defined in clause 6.2.14.
+
+$MER_{chip}$  is defined as follows. The transmitted RF waveform (after appropriate downconversion) is applied to the ideal receive chip matched filter and is sampled once per chip. The matched filter is a square-root raised cosine filter with  $\alpha = 0.25$ . No external noise (AWGN) is added to the signal. The carrier frequency offset, carrier phase offset, timing and gain may be adjusted during each burst to maximize  $MER_{chip}$ . Equalization of the received waveform is not permitted. For cases where the CM transmit equalizer is ON, the transmit equalizer coefficients may be adjusted to maximize  $MER_{chip}$ .  $MER_{chip}$  is defined at the F connector of the CM.  $MER_{chip}$  is computed by the formula:
+
+$$MER_{chip} \text{ (dB)} = 10 \times \log_{10} \left( \frac{\sum_{j=1}^N |p_j|^2}{\sum_{j=1}^N |p_j - r_j|^2} \right)$$
+
+where:
+
+$p_j$  is the  $j$ th ideal transmitted composite chip
+
+$r_j$  is the  $j$ th received composite chip
+
+$N$  is the number of composite chips observed
+
+##### 6.2.21.3.2 Requirements
+
+Unless otherwise stated, the MER MUST meet or exceed the following limits over the full transmit power range of Table 6-8 for each modulation, each modulation rate, and over the full carrier frequency range, and for S-CDMA, over any valid number of active and allocated codes. The 5-42 MHz carrier frequency range refers more precisely to  $[5 \text{ MHz} + \text{modulation rate} \times 1.25/2]$  to  $[42 \text{ MHz} - \text{modulation rate} \times 1.25/2]$ . At the break points between regions, the higher MER specification applies.
+
+###### Case 1: Flat channel, transmit equalization OFF
+
+Case 1a: for modulation rates 2.56 MHz and below:
+
+$MER_{symb} \geq 30 \text{ dB}$  over 15 to 30 MHz carrier frequency.
+
+$MER_{symb} \geq 27 \text{ dB}$  over 10 to 15 MHz and 30 to 35 MHz carrier frequency.
+
+$MER_{symb} \geq 23 \text{ dB}$  over 5 to 10 MHz and 35 to 42 MHz carrier frequency.
+
+Case 1b: for modulation rate 5.12 MHz:
+
+$MER_{symb} \geq 27 \text{ dB}$  over 15 to 30 MHz carrier frequency.
+
+$\text{MER}_{\text{symb}} \geq 24 \text{ dB}$  over 10 to 15 MHz and 30 to 35 MHz carrier frequency.
+
+$\text{MER}_{\text{symb}} \geq 20 \text{ dB}$  over 5 to 10 MHz and 35 to 42 MHz carrier frequency.
+
+###### Case 2: Flat channel, transmit equalization ON
+
+Case 2a: For TDMA/QPSK,  $\text{MER}_{\text{symb}} \geq 30 \text{ dB}$ .
+
+Case 2b: For S-CDMA and all TDMA modulations except QPSK,  $\text{MER}_{\text{symb}} \geq 35 \text{ dB}$ .
+
+Case 2c: For S-CDMA,  $\text{MER}_{\text{chip}} \geq 33 \text{ dB}$ .
+
+###### Case 3: Echo channel, transmit equalization ON
+
+Case 3a: In the presence of a single echo selected from the channel micro-reflections defined in Table 4-2, the measured  $\text{MER}_{\text{symb}}$  MUST be  $\geq 30 \text{ dB}$  for TDMA/QPSK, and  $\geq 33 \text{ dB}$  for S-CDMA and all TDMA modulations except QPSK.
+
+Case 3b: In the presence of two or three of the echoes defined in Table 4-2 (at most one of each specified magnitude and delay), the measured  $\text{MER}_{\text{symb}}$  MUST be  $\geq 29 \text{ dB}$ .
+
+Since the table does not bound echo delay for the  $-30 \text{ dBc}$  case, for testing purposes it is assumed that the time span of the echo at this magnitude is less than or equal to  $1.5 \mu\text{s}$ .
+
+The CMTS MUST provide a test mode in which it:
+
+- accepts equalizer coefficients via an external interface, e.g., Ethernet;
+- sends the coefficients to the CM's pre-equalizer via ranging response message (both set and convolve modes);
+- does not adjust the CM's frequency, timing or power.
+
+#### 6.2.21.4 Filter distortion
+
+The following requirements assume that any pre-equalization is disabled.
+
+##### 6.2.21.4.1 Amplitude
+
+The spectral mask MUST be the ideal square-root raised-cosine spectrum with  $\alpha = 0.25$ , within the ranges given in Table 6-12.
+
+**Table 6-12 – Filter amplitude distortion**
+
+| Frequency                       | Amplitude range   |                   |
+|---------------------------------|-------------------|-------------------|
+|                                 | Low               | High              |
+| $f_c - 5R_s/8$                  | –                 | $-30 \text{ dB}$  |
+| $f_c - R_s/2$                   | $-3.5 \text{ dB}$ | $-2.5 \text{ dB}$ |
+| $f_c - 3R_s/8$ to $f_c - R_s/4$ | $-0.5 \text{ dB}$ | $+0.3 \text{ dB}$ |
+| $f_c - R_s/4$ to $f_c + R_s/4$  | $-0.3 \text{ dB}$ | $+0.3 \text{ dB}$ |
+| $f_c + R_s/4$ to $f_c + 3R_s/8$ | $-0.5 \text{ dB}$ | $+0.3 \text{ dB}$ |
+| $f_c + R_s/2$                   | $-3.5 \text{ dB}$ | $-2.5 \text{ dB}$ |
+| $f_c + 5R_s/8$                  | –                 | $-30 \text{ dB}$  |
+
+Where  $f_c$  is the centre frequency,  $R_s$  is the modulation rate, and the spectral density is measured with a resolution bandwidth of 10 kHz or less.
+
+##### 6.2.21.4.2 Phase
+
+$f_c - 5R_s/8$  Hz to  $f_c + 5R_s/8$  Hz: Group delay variation MUST NOT be greater than 100 ns.
+
+#### 6.2.21.5 Carrier phase noise
+
+The upstream transmitter total integrated phase noise (including discrete spurious noise) MUST be less than or equal to  $-46$  dBc summed over the spectral regions spanning 200 Hz to 400 kHz above and below the carrier.
+
+The upstream transmitter total integrated phase noise (including discrete spurious noise) MUST be less than or equal to  $-44$  dBc summed over the spectral regions spanning 8 kHz to 3.2 MHz above and below the carrier.
+
+The CM MUST provide a test mode in which:
+
+- a continuous (non-bursted), unmodulated (CW) upstream signal is transmitted at the commanded carrier frequency, modulation rate and level. This is equivalent to replacing the chip sequence at the spreader output with the constant sequence (1, 1, 1, 1, 1, 1, ...) at nominal amplitude, equal on both I and Q;
+- the CM tracks the downstream symbol clock and uses it to generate the upstream symbol clock as in normal synchronous operation.
+
+#### 6.2.21.6 Channel frequency accuracy
+
+The CM MUST implement the assigned channel frequency within  $\pm 50$  parts per million over a temperature range of 0 to 40 degrees C up to five years from date of manufacture.
+
+#### 6.2.21.7 Modulation rate accuracy
+
+For TDMA mode, the upstream modulator MUST provide an absolute accuracy of symbol rates  $\pm 50$  parts per million over a temperature range of 0 to 40 degrees C up to five years from date of manufacture.
+
+For S-CDMA mode, the upstream modulator MUST lock the upstream chip rate to the downstream symbol rate, subject to the symbol timing jitter requirements of clause 6.2.21.8.
+
+#### 6.2.21.8 Modulation timing jitter
+
+##### 6.2.21.8.1 Symbol timing jitter for asynchronous operation
+
+For TDMA mode, peak-to-peak symbol jitter, referenced to the previous symbol zero-crossing, of the transmitted waveform, MUST be less than 0.02 of the nominal symbol duration over a 2-second period. In other words, the difference between the maximum and the minimum symbol duration during the 2-second period shall be less than 0.02 of the nominal symbol duration for each of the five upstream symbol rates.
+
+For TDMA mode, the peak-to-peak cumulative phase error, referenced to the first symbol time and with any fixed symbol frequency offset factored out, MUST be less than 0.04 of the nominal symbol duration over a 0.1-second period. In other words, the difference between the maximum and the minimum cumulative phase error during the 0.1-second period shall be less than 0.04 of the nominal symbol duration for each of the five upstream symbol rates. Factoring out a fixed symbol frequency offset is to be done by using the computed mean symbol duration during the 0.1 s.
+
+##### 6.2.21.8.2 Chip timing jitter for synchronous operation
+
+All jitter specifications assume a downstream input to the CM per clauses 6.3.5, 6.3.6, 6.3.7.2, 6.3.7.3, 6.3.9 and 6.3.10.
+
+For S-CDMA mode, upstream chip clock timing error (with the mean error subtracted out) relative to the CMTS master clock MUST be less than 0.005 RMS of the chip period over a 35-second measurement interval. This applies:
+
+- 1) to the worst-case jitter and frequency drift specified for the CMTS master clock and the CMTS downstream symbol clock in the requirements above; and
+- 2) for any round-trip propagation delay up to the maximum allowed.
+
+The CM upstream chip clock SHOULD track the jitter components below 10 Hz in the input downstream symbol clock with an error transfer function below -25 dB. The CM upstream chip clock SHOULD attenuate the jitter components in the input downstream symbol clock above 200 Hz.
+
+The CM MUST provide a test mode in which:
+
+- a continuous (non-bursted) upstream signal is transmitted at the commanded carrier frequency, modulation rate and level;
+- the chip sequence at the spreader output is replaced with an alternating binary sequence (1, -1, 1, -1, 1, -1, ...) at nominal amplitude, equal on both I and Q;
+- the CM tracks the downstream symbol clock and uses it to generate the upstream symbol clock as in normal synchronous operation.
+
+### 6.2.22 Upstream demodulator input power characteristics
+
+The maximum total input power to the upstream demodulator MUST NOT exceed 35 dBmV in the 5-42 MHz frequency range of operation.
+
+The intended received power in each carrier MUST be within the values shown in Table 6-13.
+
+**Table 6-13 – Maximum range of commanded nominal receive power in each carrier**
+
+| Modulation rate [kHz] | Maximum range [dBmV] |
+|-----------------------|----------------------|
+| 160                   | -16 to + 14          |
+| 320                   | -13 to + 17          |
+| 640                   | -10 to + 20          |
+| 1280                  | -7 to + 23           |
+| 2560                  | -4 to + 26           |
+| 5120                  | -1 to + 29           |
+
+The demodulator MUST operate within its defined performance specifications with received bursts within  $\pm 6$  dB of the nominal commanded received power.
+
+### 6.2.23 Upstream electrical output from the CM
+
+The CM MUST output an RF modulated signal with the characteristics delineated in Table 6-14.
+
+**Table 6-14 – Electrical output from the CM**
+
+| Parameter                 | Value                                                                                                                                          |
+|---------------------------|------------------------------------------------------------------------------------------------------------------------------------------------|
+| Frequency                 | 5 to 42 MHz edge to edge                                                                                                                       |
+| Level range (one channel) | TDMA:<br>+8 to +54 dBmV (32QAM, 64QAM)<br>+8 to +55 dBmV (8QAM, 16QAM)<br>+8 to +58 dBmV (QPSK)<br>S-CDMA:<br>+8 to +53 dBmV (all modulations) |
+| Modulation type           | QPSK, 8QAM, 16QAM, 32QAM, 64QAM and 128QAM                                                                                                     |
+| Modulation rate (nominal) | TDMA: 160, 320, 640, 1280, 2560 and 5120 kHz<br>S-CDMA: 1280, 2560 and 5120 kHz                                                                |
+| Bandwidth                 | TDMA: 200, 400, 800, 1600, 3200 and 6400 kHz<br>S-CDMA: 1600, 3200 and 6400 kHz                                                                |
+| Output impedance          | 75 ohms                                                                                                                                        |
+| Output return loss        | >6 dB (5-42 MHz)                                                                                                                               |
+| Connector                 | F connector per [IEC 60169-24] (common with the input)                                                                                         |
+
+## 6.3 Downstream
+
+This Recommendation applies only to a CMTS supporting exactly one QAM channel per RF output port. A CMTS supporting more than one QAM channel per RF output port would instead conform to the DOCSIS downstream radio frequency interface [DOCS9] specification in lieu of this downstream clause.
+
+### 6.3.1 Downstream protocol
+
+The downstream PMD sublayer MUST conform to Annex B of [ITU-T J.83], for low-delay video applications, with the exceptions called out in clause 6.3.2.
+
+### 6.3.2 Scalable interleaving to support low latency
+
+The downstream PMD sublayer MUST support a variable-depth interleaver with the characteristics defined in Table 6-15. The table contains a subset of interleaver modes found in Annex B of [ITU-T J.83].
+
+**Table 6-15 – Interleaver characteristics**
+
+| <b>I<br/>(number of taps)</b> | <b>J<br/>(increment)</b> | <b>Burst protection<br/>64QAM/256QAM</b> | <b>Latency<br/>64QAM/256QAM</b> |
+|-------------------------------|--------------------------|------------------------------------------|---------------------------------|
+| 8                             | 16                       | 5.9 µs/4.1 µs                            | 0.22 ms/0.15 ms                 |
+| 16                            | 8                        | 12 µs/8.2 µs                             | 0.48 ms/0.33 ms                 |
+| 32                            | 4                        | 24 µs/16 µs                              | 0.98 ms/0.68 ms                 |
+| 64                            | 2                        | 47 µs/33 µs                              | 2.0 ms/1.4 ms                   |
+| 128                           | 1                        | 95 µs/66 µs                              | 4.0 ms/2.8 ms                   |
+
+The interleaver depth, which is coded in a 4-bit control word contained in the FEC frame synchronization trailer, always reflects the interleaving in the immediately-following frame. In addition, errors are allowed while the interleaver memory is flushed after a change in interleaving is indicated.
+
+Refer to Annex B of [ITU-T J.83] for the control bit specifications required to specify which interleaving mode is used.
+
+### 6.3.3 Downstream frequency plan
+
+The downstream frequency plan should comply with harmonic related carrier (HRC), incremental related carrier (IRC) or standard (STD) North American frequency plans per [b-EIA 542]. However, operation below a centre frequency of 91 MHz is not required.
+
+### 6.3.4 CMTS electrical output
+
+The CMTS MUST output an RF modulated signal with the following characteristics defined in Table 6-16.
+
+**Table 6-16 – CMTS output**
+
+| <b>Parameter</b>                                                                                  | <b>Value</b>                                                                                                                                                                                                                                                   |
+|---------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Centre frequency ( $f_c$ )                                                                        | 91 to 857 MHz $\pm 30$ kHz <sup>a)</sup>                                                                                                                                                                                                                       |
+| Level                                                                                             | Adjustable over the range 50 to 61 dBmV                                                                                                                                                                                                                        |
+| Modulation type                                                                                   | 64QAM and 256QAM                                                                                                                                                                                                                                               |
+| Symbol rate (nominal)<br>64QAM<br>256QAM                                                          | <br>5.056941 Msymb/s<br>5.360537 Msymb/s                                                                                                                                                                                                                       |
+| Nominal channel spacing                                                                           | 6 MHz                                                                                                                                                                                                                                                          |
+| Frequency response<br>64QAM<br>256QAM                                                             | <br>-0.18 square root raised cosine shaping<br>-0.12 square root raised cosine shaping                                                                                                                                                                         |
+| Total discrete spurious inband ( $f_c \pm 3$ MHz)<br>Inband spurious and noise ( $f_c \pm 3$ MHz) | <br>$\leq 57$ dBc<br>$\leq 48$ dBc; where channel spurious and noise includes all discrete spurious, noise, carrier leakage, clock lines, synthesizer products and other undesired transmitter products. Noise within $\pm 50$ kHz of the carrier is excluded. |
+| Adjacent channel ( $f_c \pm 3.0$ MHz) to ( $f_c \pm 3.75$ MHz)                                    | $\leq 58$ dBc in 750 kHz                                                                                                                                                                                                                                       |
+
+**Table 6-16 – CMTS output**
+
+| Parameter                                                                                                                     | Value                                                                                                                                                                                            |
+|-------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Adjacent channel ( $f_c \pm 3.75$ MHz) to ( $f_c \pm 9$ MHz)                                                                  | $\leq 62$ dBc, in 5.25 MHz, excluding up to 3 spurs, each of which must be $\leq 60$ dBc when measured in a 10-kHz band.                                                                         |
+| Next adjacent channel ( $f_c \pm 9$ MHz), to ( $f_c \pm 15$ MHz)                                                              | Less than the greater of $-65$ dBc or $-12$ dBmV in 6 MHz, excluding up to three discrete spurs. The total power in the spurs must be $\leq 60$ dBc when each is measured with 10-kHz bandwidth. |
+| Other channels (47 MHz to 1000 MHz)                                                                                           | $< -12$ dBmV in each 6-MHz channel, excluding up to three discrete spurs. The total power in the spurs must be $\leq 60$ dBc when each is measured with 10-kHz bandwidth.                        |
+| Phase noise                                                                                                                   | 1 to 10 kHz: $-33$ dBc double-sided noise power<br>10 to 50 kHz: $-51$ dBc double-sided noise power<br>50 kHz to 3 MHz: $-51$ dBc double-sided noise power                                       |
+| Output impedance                                                                                                              | 75 ohms                                                                                                                                                                                          |
+| Output return loss                                                                                                            | $> 14$ dB within an output channel up to 750 MHz;<br>$> 13$ dB in an output channel above 750 MHz                                                                                                |
+| Connector                                                                                                                     | F connector per [IEC 60169-24]                                                                                                                                                                   |
+| <sup>a)</sup> $\pm 30$ kHz includes an allowance of 25 kHz for the largest-frequency offset normally built into upconverters. |                                                                                                                                                                                                  |
+
+### 6.3.5 Downstream electrical input to CM
+
+The CM MUST be able to locate and accept RF modulated signals located within channels defined in [b-EIA 542] for harmonic related carrier (HRC), incremental related carrier (IRC) and standard (STD) North American frequency plans. Operation below a centre frequency of 91 MHz is not required. The signals will have the characteristics defined in Table 6-17.
+
+**Table 6-17 – Electrical input to CM**
+
+| Parameter                 | Value                                                                                                                          |
+|---------------------------|--------------------------------------------------------------------------------------------------------------------------------|
+| Centre frequency          | 91 to 857 MHz $\pm 30$ kHz                                                                                                     |
+| Level range (one channel) | $-15$ dBmV to $+15$ dBmV                                                                                                       |
+| Modulation type           | 64QAM and 256QAM                                                                                                               |
+| Symbol rate (nominal)     | 5.056941 Msymb/s (64QAM) and 5.360537 Msymb/s (256QAM)                                                                         |
+| Bandwidth                 | 6 MHz (alpha = 0.18 square root raised cosine shaping for 64QAM and alpha = 0.12 square root raised cosine shaping for 256QAM) |
+
+**Table 6-17 – Electrical input to CM**
+
+| Parameter                      | Value                                                   |
+|--------------------------------|---------------------------------------------------------|
+| Total input power (40-900 MHz) | <30 dBmV                                                |
+| Input (load) impedance         | 75 ohms                                                 |
+| Input return loss              | >6 dB (88-860 MHz)                                      |
+| Connector                      | F connector per [IEC 60169-24] (common with the output) |
+
+### 6.3.6 CM BER performance
+
+The bit-error-rate performance of a CM MUST be as described in this clause. The requirements apply to the  $I = 128$ ,  $J = 1$  mode of interleaving.
+
+#### 6.3.6.1 64QAM
+
+##### 6.3.6.1.1 64QAM CM BER performance
+
+Implementation loss of the CM MUST be such that the CM achieves a post-FEC BER less than or equal to  $10^{-8}$  when operating at a carrier to noise ratio ( $E_s/N_0$ ) of 23.5 dB or greater.
+
+##### 6.3.6.1.2 64QAM image rejection performance
+
+Performance as described in clause 6.3.6.1.1 MUST be met with an analogue or digital signal at +10 dBc in any portion of the RF band other than the adjacent channels.
+
+##### 6.3.6.1.3 64QAM adjacent channel performance
+
+Performance as described in clause 6.3.6.1.1 MUST be met with a digital signal at 0 dBc in the adjacent channels.
+
+Performance as described in clause 6.3.6.1.1 MUST be met with an analogue signal at +10 dBc in the adjacent channels.
+
+Performance as described in clause 6.3.6.1.1, with an additional 0.2-dB allowance, MUST be met with a digital signal at +10 dBc in the adjacent channels.
+
+#### 6.3.6.2 256QAM
+
+##### 6.3.6.2.1 256QAM CM BER performance
+
+Implementation loss of the CM MUST be such that the CM achieves a post-FEC BER less than or equal to  $10^{-8}$  when operating at a carrier to noise ratio ( $E_s/N_0$ ) as shown below.
+
+Input receive signal level  $E_s/N_0$
+
+–6 dBmV to +15 dBmV 30 dB or greater
+
+Less than –6 dBmV down to –15 dBmV 33 dB or greater
+
+##### 6.3.6.2.2 256QAM image rejection performance
+
+Performance as described in clause 6.3.6.2.1 MUST be met with an analogue or a digital signal at +10 dBc in any portion of the RF band other than the adjacent channels.
+
+##### 6.3.6.2.3 256QAM adjacent channel performance
+
+Performance as described in clause 6.3.6.2.1 MUST be met with an analogue or a digital signal at 0 dBc in the adjacent channels.
+
+Performance as described in clause 6.3.6.2.1, with an additional 0.5-dB allowance, MUST be met with an analogue signal at +10 dBc in the adjacent channels.
+
+Performance as described in clause 6.3.6.2.1, with an additional 1.0-dB allowance, MUST be met with a digital signal at +10 dBc in the adjacent channels.
+
+### 6.3.7 CMTS timestamp jitter
+
+The CMTS timestamp jitter MUST be less than 500 ns peak-to-peak at the output of the downstream transmission convergence sublayer. This jitter is relative to an ideal downstream transmission convergence sublayer that transfers the MPEG packet data to the downstream physical media dependent sublayer with a perfectly continuous and smooth clock at the MPEG packet data rate. Downstream physical media dependent sublayer processing MUST NOT be considered in timestamp generation and transfer to the downstream physical media dependent sublayer.
+
+Thus, any two timestamps N1 and N2 (N2 > N1) which were transferred to the downstream physical media dependent sublayer, at times T1 and T2 respectively, must satisfy the following relationship:
+
+$$\left| \frac{N2 - N1}{f_{CMTS}} - (T2 - T1) \right| < 500 \times 10^{-9}$$
+
+In the equation, the value of (N2 – N1) is assumed to account for the effect of rollover of the timebase counter, and T1 and T2 represent time in seconds.  $f_{CMTS}$  is the actual frequency of the CMTS master timebase and may include a fixed frequency offset from the nominal frequency of 10.24 MHz. This frequency offset is bounded by a requirement further below in this clause.
+
+The jitter includes inaccuracy in timestamp value and the jitter in all clocks. The 500 ns allocated for jitter at the downstream transmission convergence sublayer output MUST be reduced by any jitter that is introduced by the downstream physical media dependent sublayer.
+
+The CM is expected to meet the burst timing accuracy requirements in clause 6.2.19 when the timestamps contain this worst-case jitter.
+
+NOTE – Jitter is the error (i.e., measured) relative to the CMTS master clock (the CMTS master clock is the 10.24-MHz clock used for generating the timestamps).
+
+#### 6.3.7.1 CMTS master clock jitter for asynchronous operation
+
+The CMTS 10.24-MHz master clock MUST have frequency accuracy of  $\leq \pm 5$  ppm, drift rate  $\leq 10^{-8}$  per second, and edge jitter of  $\leq 10$  ns peak-to-peak ( $\pm 5$  ns) over a temperature range of 0 to 40 degrees C up to ten years from date of manufacture<sup>5</sup> (the drift rate and jitter requirements on the CMTS master clock implies that the duration of two adjacent segments of 10'240'000 cycles will be within 30 ns, due to 10 ns jitter on each segments' duration, and 10 ns due to frequency drift. Durations of other counter lengths also may be deduced: adjacent 1'024'000 segments,  $\leq 21$  ns; 1'024'000 length segments separated by one 10'240'000 cycle segment,  $\leq 30$  ns; adjacent 102'400'000 segments,  $\leq 120$  ns. The CMTS master clock MUST meet such test limits in 99% or more measurements).
+
+---
+
+<sup>5</sup> This Recommendation MAY also be met by synchronizing the CMTS master clock oscillator to an external frequency reference source. If this approach is used, the internal CMTS master clock MUST have frequency accuracy of  $\pm 20$  ppm over a temperature range of 0 to 40 degrees C up to ten years from date of manufacture when no frequency reference source is connected. The drift rate and edge jitter MUST be as specified above.
+
+#### 6.3.7.2 CMTS master clock jitter for synchronous operation
+
+In addition to the requirements in clause 6.3.7.1, the 10.24 MHz CMTS master clock MUST meet the following double sideband phase noise requirements over the specified frequency ranges:
+
+|                                                                     |                      |
+|---------------------------------------------------------------------|----------------------|
+| $< [-50 + 20 \cdot \log(f_{MC}/10.24)]$ dBc (i.e., $< 0.05$ ns RMS) | 10 to 100 Hz         |
+| $< [-58 + 20 \cdot \log(f_{MC}/10.24)]$ dBc (i.e., $< 0.02$ ns RMS) | 100 to 1 kHz         |
+| $< [-50 + 20 \cdot \log(f_{MC}/10.24)]$ dBc (i.e., $< 0.05$ ns RMS) | 1 to 10 kHz          |
+| $< [-50 + 20 \cdot \log(f_{MC}/10.24)]$ dBc (i.e., $< 0.05$ ns RMS) | 10 kHz to $f_{MC}/2$ |
+
+where  $f_{MC}$  is the frequency of the measured master clock in MHz. The value of  $f_{MC}$  MUST be either an integral multiple or divisor of 10.24 MHz. For example, if a 20.48-MHz oscillator is used as the master clock frequency source, and there is no explicit 10.24-MHz clock to test, the 20.48 MHz clock may be used with  $f_{MC}$  equal to 20.48 in the above expressions.
+
+#### 6.3.7.3 CMTS master clock frequency drift for synchronous operation
+
+The frequency of the master clock MUST NOT drift more than  $1e-8$  per second.
+
+### 6.3.8 CMTS clock generation
+
+The CMTS has the following three options related to the synchronization of the CMTS master clock and the downstream symbol clock:
+
+- 1) not locked;
+- 2) downstream symbol clock locked to CMTS master clock;
+- 3) CMTS master clock locked to downstream symbol clock.
+
+For S-CDMA operation, the master clock and the downstream symbol clock MUST be locked using either option 2 or 3.
+
+Let  $f_b'$  represent the rate of the downstream symbol clock which is locked to the CMTS master clock, and let  $f_m$  represent the rate of the CMTS master clock locked to the downstream symbol clock. Let  $f_b$  represent the nominal specified downstream symbol rate, and let  $f_m$  represent the nominal CMTS master clock rate (10.24 MHz).
+
+With the downstream symbol clock locked to the CMTS master clock, the following equation MUST hold:
+
+$$f_b' = f_m \times M/N$$
+
+With the CMTS master clock locked to the downstream symbol clock, the following equation MUST hold:
+
+$$f_m' = f_b \times N/M$$
+
+M and N MUST be unsigned integer values each representable in 16 bits (these are specified in the channel TLV parameters of the UCD). When the downstream symbol clock and the CMTS master clock are not locked together, the values of M and N are not valid and are ignored by the CM.
+
+The values of M and N MUST result in a value of  $f_b'$  or  $f_m'$ , which is not more than  $\pm 1$  ppm from its specified nominal value. Table 6-18 lists the downstream modes of operation, their associated nominal symbol rates,  $f_b$ , example values for M and N, the resulting synchronized clock rates, and their offsets from their nominal values.
+
+**Table 6-18 – Downstream symbol rates and example parameters for synchronization with the CMTS master clock**
+
+| Downstream mode | Nominal specified symbol rate, $f_b$ [MHz] | M/N     | CMTS master clock rate, $f_m'$ [MHz] | Downstream symbol rate, $f_b'$ [MHz] | Offset from nominal |
+|-----------------|--------------------------------------------|---------|--------------------------------------|--------------------------------------|---------------------|
+| Annex B, 64QAM  | 5.056941                                   | 401/812 | 10.239990...                         | 5.056945...                          | 0.95 ppm            |
+| Annex B, 256QAM | 5.360537                                   | 78/149  | 10.240000...                         | 5.360536...                          | 0.02 ppm            |
+
+### 6.3.9 CMTS downstream symbol clock jitter for synchronous operation
+
+The downstream symbol clock MUST meet the following double sideband phase noise requirements over the specified frequency ranges:
+
+|                                                                     |                         |
+|---------------------------------------------------------------------|-------------------------|
+| $< [-53 + 20 \cdot \log(f_{DS}/5.057)]$ dBc (i.e., $< 0.07$ ns RMS) | 10 to 100 Hz            |
+| $< [-53 + 20 \cdot \log(f_{DS}/5.057)]$ dBc (i.e., $< 0.07$ ns RMS) | 100 to 1 kHz            |
+| $< [-53 + 20 \cdot \log(f_{DS}/5.057)]$ dBc (i.e., $< 0.07$ ns RMS) | 1 to 10 kHz             |
+| $< [-36 + 20 \cdot \log(f_{DS}/5.057)]$ dBc (i.e., $< 0.5$ ns RMS)  | 10 to 100 kHz           |
+| $< [-30 + 20 \cdot \log(f_{DS}/5.057)]$ dBc (i.e., $< 1$ ns RMS)    | 100 kHz to $(f_{DS}/2)$ |
+
+where  $f_{DS}$  is the frequency of the measured clock in MHz. The value of  $f_{DS}$  MUST be an integral multiple or divisor of the downstream symbol clock. For example, an  $f_{DS} = 20.227764$ -MHz clock may be measured if there is no explicit 5.056941 MHz-clock available.
+
+The CMTS MUST provide a test mode in which:
+
+- the downstream QAM symbol sequence is replaced with an alternating binary sequence (1, -1, 1, -1, 1, -1, ...) at nominal amplitude, on both I and Q;
+- the CMTS generates the downstream symbol clock from the 10.24-MHz reference clock as in normal synchronous operation.
+
+If an explicit downstream symbol clock that is capable of meeting the above phase noise requirements is available (e.g., a smooth clock without clock domain jitter), this test mode is not required.
+
+### 6.3.10 CMTS downstream symbol clock drift for synchronous operation
+
+The frequency of the downstream symbol clock MUST NOT drift more than  $1e-8$  per second.
+
+# 7 Downstream transmission convergence sublayer
+
+## 7.1 Introduction
+
+This clause applies to the first technology option referred to in clause 1.1. For the second and third options, refer to Annexes F and J, respectively.
+
+In order to improve demodulation robustness, facilitate common receiving hardware for both video and data, and provide an opportunity for the possible future multiplexing of video and data over the PMD sublayer bitstream defined in clause 6, a sublayer is interposed between the downstream PMD sublayer and the data-over-cable MAC sublayer.
+
+The downstream bitstream is defined as a continuous series of 188-byte MPEG [ITU-T H.222.0] packets. These packets consist of a 4-byte header followed by 184 bytes of payload. The header identifies the payload as belonging to the data-over-cable MAC. Other values of the header may
+
+indicate other payloads. The mixture of MAC payloads and those of other services is optional and is controlled by the CMTS.
+
+Figure 7-1 illustrates the interleaving of data-over-cable (DOC) MAC bytes with other digital information (digital video in the example shown).
+
+|                |                       |
+|----------------|-----------------------|
+| Header = DOC   | DOC MAC payload       |
+| Header = video | Digital video payload |
+| Header = video | Digital video payload |
+| Header = DOC   | DOC MAC payload       |
+| Header = video | Digital video payload |
+| Header = DOC   | DOC MAC payload       |
+| Header = video | Digital video payload |
+| Header = video | Digital video payload |
+| Header = video | Digital video payload |
+
+**Figure 7-1 – Example of interleaving MPEG packets in downstream**
+
+## 7.2 MPEG packet format
+
+The format of an MPEG packet carrying DOCS data is shown in Figure 7-2. The packet consists of a 4-byte MPEG header, a pointer\_field (not present in all packets) and the DOCS payload.
+
+|                          |                           |                                    |
+|--------------------------|---------------------------|------------------------------------|
+| MPEG header<br>(4 bytes) | pointer_field<br>(1 byte) | DOCS payload<br>(183 or 184 bytes) |
+|--------------------------|---------------------------|------------------------------------|
+
+**Figure 7-2 – Format of an MPEG packet**
+
+## 7.3 MPEG header for DOCS data-over-cable
+
+The format of the MPEG transport stream header is defined in clause 2.4 of [ITU-T H.222.0]. The particular field values that distinguish data-over-cable MAC streams are defined in Table 7-1. Field names are from [ITU-T H.222.0].
+
+**Table 7-1 – MPEG header format for DOCS data-over-cable packets**
+
+| Field                        | Length (bits) | Description                                                                                                                                                                        |
+|------------------------------|---------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| sync_byte                    | 8             | 0 × 47; MPEG packet sync byte                                                                                                                                                      |
+| transport_error_indicator    | 1             | Indicates an error has occurred in the reception of the packet. This bit is reset to zero by the sender, and is set to one whenever an error occurs in transmission of the packet. |
+| payload_unit_start_indicator | 1             | A value of one indicates the presence of a pointer_field as the first byte of the payload (fifth byte of the packet)                                                               |
+| transport_priority           | 1             | Reserved; set to zero                                                                                                                                                              |
+| PID (see Note)               | 13            | DOCS data-over-cable well-known PID (0x1FFE)                                                                                                                                       |
+| transport_scrambling_control | 2             | Reserved; set to '00'                                                                                                                                                              |
+
+**Table 7-1 – MPEG header format for DOCS data-over-cable packets**
+
+| Field                    | Length (bits) | Description                                                      |
+|--------------------------|---------------|------------------------------------------------------------------|
+| adaptation_field_control | 2             | '01'; use of the adaptation_field is NOT ALLOWED on the DOCS PID |
+| continuity_counter       | 4             | Cyclic counter within this PID                                   |
+
+NOTE – The MPEG header consists of 4 bytes that begin the 188-byte MPEG packet. The format of the header for use on a DOCS data-over-cable PID is restricted to that shown in this table. The header format conforms to the MPEG standard, but its use is restricted in this Recommendation to NOT ALLOW inclusion of an adaptation\_field in the MPEG packets.
+
+## 7.4 MPEG payload for DOCS data-over-cable
+
+The MPEG payload portion of the MPEG packet will carry the DOCS MAC frames. The first byte of the MPEG payload will be a 'pointer\_field' if the payload\_unit\_start\_indicator (PUSI) of the MPEG header is set.
+
+### 7.4.1 stuff\_byte
+
+This Recommendation defines a stuff\_byte pattern having a value (0xFF) that is used within the DOCS payload to fill any gaps between the DOCS MAC frames. This value is chosen as an unused value for the first byte of the DOCS MAC frame. The 'FC' byte of the MAC header will be defined to never contain this value (FC\_TYPE = '11' indicates a MAC-specific frame, and FC\_PARM = '11111' is not currently used and, according to this Recommendation, is defined as an illegal value for FC\_PARM).
+
+### 7.4.2 pointer\_field
+
+The pointer\_field is present as the fifth byte of the MPEG packet (first byte following the MPEG header) whenever the PUSI is set to one in the MPEG header. The interpretation of the pointer\_field is as follows.
+
+The pointer\_field contains the number of bytes in this packet that immediately follow the pointer\_field that the CM decoder must skip past before looking for the beginning of a DOCS MAC frame. A pointer field MUST be present if it is possible to begin a data-over-cable MAC frame in the packet, and MUST point to either:
+
+- 1) the beginning of the first MAC frame to start in the packet; or
+- 2) to any stuff\_byte preceding the MAC frame.
+
+## 7.5 Interaction with the MAC sublayer
+
+MAC frames may begin anywhere within an MPEG packet, MAC frames may span MPEG packets, and several MAC frames may exist within an MPEG packet.
+
+The following figures show the format of the MPEG packets that carry DOCS MAC frames. In all cases, the PUSI flag indicates the presence of the pointer\_field as the first byte of the MPEG payload.
+
+Figure 7-3 shows a MAC frame that is positioned immediately after the pointer\_field byte. In this case, pointer\_field is zero, and the DOCS decoder will begin searching for a valid FC byte at the byte immediately following the pointer\_field.
+
+|                           |                        |                                |                              |
+|---------------------------|------------------------|--------------------------------|------------------------------|
+| MPEG header<br>(PUSI = 1) | pointer_field<br>(= 0) | MAC frame<br>(up to 183 bytes) | stuff_byte(s)<br>(0 or more) |
+|---------------------------|------------------------|--------------------------------|------------------------------|
+
+**Figure 7-3 – Packet format where a MAC frame immediately follows the pointer\_field**
+
+Figure 7-4 shows the more general case where a MAC frame is preceded by the tail of a previous MAC frame and a sequence of stuffing bytes. In this case, the pointer\_field still identifies the first byte after the tail of frame #1 (a stuff\_byte) as the position where the decoder should begin searching for a legal MAC sublayer FC value. This format allows the multiplexing operation in the CMTS to immediately insert a MAC frame that is available for transmission if that frame arrives after the MPEG header and pointer\_field have been transmitted.
+
+|                           |                        |                                   |                              |                       |
+|---------------------------|------------------------|-----------------------------------|------------------------------|-----------------------|
+| MPEG header<br>(PUSI = 1) | pointer_field<br>(= M) | Tail of MAC frame #1<br>(M bytes) | stuff_byte(s)<br>(0 or more) | Start of MAC frame #2 |
+|---------------------------|------------------------|-----------------------------------|------------------------------|-----------------------|
+
+**Figure 7-4 – Packet format with MAC frame preceded by stuffing bytes**
+
+In order to facilitate multiplexing of the MPEG packet stream carrying DOCS data with other MPEG-encoded data, the CMTS SHOULD NOT transmit MPEG packets with the DOCS PID which contain only stuff\_bytes in the payload area. MPEG null packets SHOULD be transmitted instead. Note that there are timing relationships implicit in the DOCS MAC sublayer which must also be preserved by any MPEG multiplexing operation.
+
+Figure 7-5 shows that multiple MAC frames may be contained within the MPEG packet. The MAC frames may be concatenated one after the other or be separated by an optional sequence of stuffing bytes.
+
+|                           |                        |              |              |                              |              |
+|---------------------------|------------------------|--------------|--------------|------------------------------|--------------|
+| MPEG header<br>(PUSI = 1) | pointer_field<br>(= 0) | MAC frame #1 | MAC frame #2 | stuff_byte(s)<br>(0 or more) | MAC frame #3 |
+|---------------------------|------------------------|--------------|--------------|------------------------------|--------------|
+
+**Figure 7-5 – Packet format showing multiple MAC frames in a single packet**
+
+Figure 7-6 shows the case where a MAC frame spans multiple MPEG packets. In this case, the pointer\_field of the succeeding frame points to the byte following the last byte of the tail of the first frame.
+
+|                           |                                             |                                   |                                            |                                    |
+|---------------------------|---------------------------------------------|-----------------------------------|--------------------------------------------|------------------------------------|
+| MPEG header<br>(PUSI = 1) | pointer_field<br>(= 0)                      | stuff_byte(s)<br>(0 or more)      | Start of MAC frame #1<br>(up to 183 bytes) |                                    |
+| MPEG header<br>(PUSI = 0) | Continuation of MAC frame #1<br>(184 bytes) |                                   |                                            |                                    |
+| MPEG header<br>(PUSI = 1) | pointer_field<br>(= M)                      | Tail of MAC frame #1<br>(M bytes) | stuff_byte(s)<br>(0 or more)               | Start of MAC frame #2<br>(M bytes) |
+
+**Figure 7-6 – Packet format where a MAC frame spans multiple packets**
+
+The transmission convergence sublayer must operate closely with the MAC sublayer in providing an accurate timestamp to be inserted into the time synchronization message (refer to clauses 8.3.2 and 9.3).
+
+## **7.6 Interaction with the Physical Layer**
+
+The MPEG-2 packet stream **MUST** be encoded according to Annex B of [ITU-T J.83], including MPEG-2 transport framing using a parity checksum as described in Annex B of [ITU-T J.83].
+
+## **7.7 MPEG header synchronization and recovery**
+
+The MPEG-2 packet stream **SHOULD** be declared "in frame" (i.e., correct packet alignment has been achieved) when five consecutive correct parity checksums, each 188 bytes from the previous one, have been received.
+
+The MPEG-2 packet stream **SHOULD** be declared "out of frame," and a search for correct packet alignment started, when nine consecutive incorrect parity checksums are received.
+
+The format of MAC frames is described in detail in clause 8.
+
+# **8 Media access control specification**
+
+## **8.1 Introduction**
+
+### **8.1.1 Overview**
+
+This clause describes version 2.0 of the DOCS MAC protocol. Some of the MAC protocol highlights include:
+
+- bandwidth allocation controlled by CMTS;
+- a stream of mini-slots in the upstream;
+- dynamic mix of contention- and reservation-based upstream transmit opportunities;
+- bandwidth efficiency through support of variable-length packets;
+- extensions provided for future support of ATM or other data PDU;
+- Quality of service including:
+  - support for bandwidth and latency guarantees;
+  - packet classification;
+  - dynamic service establishment.
+- extensions provided for security at the data link layer;
+- support for a wide range of data rates.
+
+### **8.1.2 Definitions**
+
+#### **8.1.2.1 MAC-sublayer domain**
+
+A MAC-sublayer domain is a collection of upstream and downstream channels for which a single MAC allocation and management protocol operates. Its attachments include one CMTS and some number of CMs. The CMTS **MUST** service all of the upstream and downstream channels; each CM accesses one logical upstream and one downstream channel at a time. The CMTS **MUST** police and discard any packets received that have a source MAC address that is not a unicast MAC address. The upstream channels may be any combination of DOCS 1.x or 2.0 formats. A single upstream channel **MAY** transport DOCS 1.x and 2.0 bursts.
+
+#### **8.1.2.2 MAC service access point**
+
+A MAC service access point (MSAP) is an attachment to a MAC-sublayer domain (refer to clause 5.2).
+
+#### 8.1.2.3 Service flows
+
+The concept of service flows is central to the operation of the MAC protocol. Service flows provide a mechanism for upstream and downstream quality of service management. In particular, they are integral to bandwidth allocation.
+
+A service flow ID defines a particular unidirectional mapping between a CM and the CMTS. Active upstream service flow IDs also have associated service IDs or SIDs. Upstream bandwidth is allocated to SIDs, and hence to CMs, by the CMTS. Service IDs provide the mechanism by which upstream quality of service is implemented.
+
+The CMTS MAY assign one or more service flow IDs (SFIDs) to each CM, corresponding to the service flows required by the CM. This mapping can be negotiated between the CMTS and the CM during CM registration or via dynamic service establishment (refer to clause 11.4).
+
+In a basic CM implementation, two service flows (one upstream, one downstream) could be used, for example, to offer best-effort IP service. However, the service flow concept allows for more complex CMs to be developed with support for multiple service classes while supporting interoperability with more basic modems. With these more complex modems, it is possible that certain service flows will be configured in such a way that they cannot carry all types of traffic. That is, they may have a maximum packet size limitation or be restricted to small fixed size unsolicited grants. Furthermore it might not be appropriate to send other kinds of data on service flows that are being used for constant bit rate (CBR)-type applications.
+
+Even in these complex modems, it is necessary to be able to send certain upstream packets needed for MAC management, SNMP management, key management, etc. For the network to function properly, all CMs MUST support at least one upstream and one downstream service flow. These service flows MUST always be provisioned to allow the CM to request and to send the largest possible unconcatenated MAC frame (refer to clause 8.2.2). These service flows are referred to as the upstream and downstream primary service flows. The SID assigned to the upstream primary service flow is referred to as the primary SID.
+
+The primary SID MUST always be assigned to the first provisioned upstream service flow during the registration process (which may or may not be the same temporary SID used for the registration process). The primary service flows MUST be immediately activated at registration time. The primary SID MUST always be used for periodic ranging after registration. The primary service flows MAY be used for traffic. All unicast service flows MUST use the security association defined for the primary service flow (refer to [DOCS8]).
+
+All service flow IDs are unique within a single MAC-sublayer domain. The mapping of a unicast service identifier to an active/admitted service flow MUST be unique within a single MAC-sublayer domain. The length of the service flow ID is 32 bits. The length of the service ID is 14 bits (although the service ID is sometimes carried in the low-order bits of a 16-bit field).
+
+Unicast flows on different logical upstreams that are attached to a single MAC-sublayer domain MAY be assigned the same SID, as long as the SFIDs are unique.
+
+#### 8.1.2.4 Upstream intervals, mini-slots and 6.25-microsecond increments
+
+The upstream transmission time-line is divided into intervals by the upstream bandwidth allocation mechanism. Each interval is an integral number of mini-slots. A "mini-slot" is the unit of granularity for upstream transmission opportunities. There is no implication that any PDU can actually be transmitted in a single mini-slot. Each interval is labelled with a usage code which defines both the type of traffic that can be transmitted during that interval and the physical-layer modulation encoding. The usage code values are defined in Table 8-20 and allowed use is defined in clause 8.3. The binding of these values to physical-layer parameters is defined in Table 8-18.
+
+##### 8.1.2.4.1 TDMA mode
+
+For DOCS 1.x channels, a mini-slot is a power-of-two multiple of 6.25- $\mu$ s increments, i.e., 2, 4, 8, 16, 32, 64 or 128 times 6.25  $\mu$ s. For DOCS 2.0 TDMA, a mini-slot is a power-of-two multiple of 6.25- $\mu$ s increments: 1, 2, 4, 8, 16, 32, 64 or 128 times 6.25  $\mu$ s. The relationship between mini-slots, bytes, and time ticks is described further in clause 9.3.4.
+
+##### 8.1.2.4.2 S-CDMA mode
+
+For DOCS 2.0 S-CDMA channels, a mini-slot is not restricted to be a power-of-two multiple of 6.25- $\mu$ s increments. Instead a mini-slot is a unit of capacity that is dependent on the modulation rate, number of spreading codes, and number of spreading intervals configured for the upstream channel<sup>6</sup>. While the channel may be configured such that the time duration of a mini-slot is a power-of-two multiple of 6.25- $\mu$ s increments, there is no special significance to 6.25- $\mu$ s time ticks for S-CDMA channels. The relationship between mini-slots and S-CDMA framing is described further in clause 6.2.11. The relationship between mini-slots, bytes and time ticks is described further in clause 9.3.4.
+
+#### 8.1.2.5 MAC frame
+
+A MAC layer frame is a unit of data exchanged between two (or more) entities at the data link layer. A MAC frame consists of a MAC header (beginning with a frame control byte; see Figure 8-3), and may incorporate a variable-length data PDU. The variable-length PDU includes a pair of 48-bit addresses, data and a CRC. In special cases, the MAC header may encapsulate multiple MAC frames (see clause 8.2.5.5) into a single MAC frame. The MAC layer definition of a frame is different from any physical layer or MPEG layer definition of a frame.
+
+#### 8.1.2.6 Logical upstream channels
+
+The MAC layer deals with logical upstreams. A logical upstream is identified with an upstream channel ID which is unique within the MSAP. A logical upstream consists of a contiguous stream of mini-slots which are described and allocated by the UCD and MAP messages associated with a channel ID. A CM can only register to operate on a single logical upstream channel.
+
+There are 4 distinct types of logical upstream:
+
+- Type 1: DOCS 1.x upstreams that support no DOCS 2.0 TDMA features;
+- Type 2: Mixed upstreams that support DOCS 1.x and DOCS 2.0 TDMA bursts;
+- Type 3A: DOCS 2.0 TDMA-only upstreams that cannot support DOCS 1.x CMs;
+- Type 3S: S-CDMA upstreams that support only CMs operating in S-CDMA mode.
+
+All valid logical upstreams fall into one of these 4 categories.
+
+In DOCS 2.0 it is possible for multiple logical upstreams to share the same spectrum. When this occurs, the logical upstreams sharing the same spectrum are time domain multiplexed and only one is active at any time. The only exception to this rule is that it is possible for the broadcast initial maintenance regions to be simultaneous. When a logical upstream channel is inactive, its mini-slots are allocated to the NULL SID by its associated MAP messages. Having multiple logical upstreams that share the same spectrum is the only way to have modems operating in S-CDMA mode share the same upstream spectrum with modems not operating in S-CDMA mode.
+
+The CMTS MUST support all four logical upstream channel types individually, and MUST also support the following three combinations of two logical upstream channels sharing the same upstream spectrum:
+
+---
+
+<sup>6</sup> This relationship holds true on an S-CDMA channel even if the burst parameters for a particular IUC have the spreader disabled.
+
+- one DOCS 1.x-only logical channel plus one S-CDMA logical channel with the same modulation rate on both logical channels;
+- one mixed DOCS 1.x and A-TDMA logical channel plus one S-CDMA logical channel with the same modulation rate on both logical channels;
+- one A-TDMA-only logical channel plus one S-CDMA logical channel with the same modulation rate on both logical channels.
+
+The CMTS MAY support other combinations of logical channels sharing the same upstream spectrum, including combinations of logical channels with different modulation rates.
+
+#### **8.1.2.7 DOCS 2.0-only logical upstreams**
+
+DOCS 2.0-only logical upstreams have operational parameters in their associated UCD messages that prevent the operation of DOCS 1.x CMs. See clause 8.3.3 for a detailed description of which parameter values make a channel a DOCS 2.0-only upstream. The UCD messages for DOCS 2.0-only logical upstreams use a different MAC management message type (see clause 8.3.1) than do UCD messages for channels that can support 1.x CMs. This prevents 1.x CMs from attempting to use DOCS 2.0-only upstreams or from being confused by UCD messages for those channels. A logical upstream is a DOCS 2.0-only upstream if and only if it is an S-CDMA upstream or a DOCS 2.0 TDMA-only upstream.
+
+### **8.1.3 Future use**
+
+A number of fields are defined as being "for future use" or reserved in the various MAC frames described in this Recommendation. These fields MUST NOT be interpreted or used in any manner by this version (2.0) of the MAC protocol.
+
+## **8.2 MAC frame formats**
+
+### **8.2.1 Generic MAC frame format**
+
+A MAC frame is the basic unit of transfer between MAC sublayers at the CMTS and the cable modem. The same basic structure is used in both the upstream and downstream directions. MAC frames are variable in length. The term "frame" is used in this context to indicate a unit of information that is passed between MAC sublayer peers. This is not to be confused with the term "framing" that indicates some fixed timing relationship.
+
+There are three distinct regions to consider, as shown in Figure 8-1. Preceding the MAC frame is either PMD sublayer overhead (upstream) or an MPEG transmission convergence header (downstream). The first part of the MAC frame is the MAC header. The MAC header uniquely identifies the contents of the MAC frame. Following the header is the optional data PDU region. The format of the data PDU and whether it is even present is described in the MAC header.
+
+![Diagram of Generic MAC frame format showing PMD overhead (upstream), MAC header, Data PDU (optional), and MPEG PSI header (downstream).](c7111699f84f3e2bc4016b7876f10de6_img.jpg)
+
+The diagram illustrates the structure of a Generic MAC frame. It shows a vertical stack of components. At the top is a box labeled 'PMD overhead (upstream)'. Below this is a box containing two side-by-side components: 'MAC header (see Figure 8-3)' on the left and 'Data PDU (optional) (see Figure 8-4)' on the right. A horizontal curly brace underneath this box is labeled 'MAC frame'. At the bottom of the stack is a box labeled 'MPEG PSI header (downstream) (see Table 7-1)'. The text 'J.122\_F8-1' is located to the right of the MAC frame box.
+
+Diagram of Generic MAC frame format showing PMD overhead (upstream), MAC header, Data PDU (optional), and MPEG PSI header (downstream).
+
+**Figure 8-1 – Generic MAC frame format**
+
+#### 8.2.1.1 PMD overhead
+
+In the upstream direction, the PHY layer indicates the start of the MAC frame to the MAC sublayer. From the MAC sublayer's perspective, it only needs to know the total amount of overhead so it can account for it in the bandwidth allocation process. More information on this may be found in the PMD sublayer clause (clause 6).
+
+The FEC overhead is spread throughout the MAC frame and is assumed to be transparent to the MAC data stream. The MAC sublayer does need to be able to account for the overhead when doing bandwidth allocation. More information on this may be found in the upstream bandwidth allocation clause (refer to clause 9.1).
+
+#### 8.2.1.2 MAC frame transport
+
+The transport of MAC frames by the PMD sublayer for upstream channels is shown in Figure 8-2.
+
+![Diagram illustrating Upstream MAC/PMD convergence. The diagram shows three MAC frames being transmitted from the MAC sublayer to the PMD sublayer. Each MAC frame is mapped to a burst of mini-slots. The PMD sublayer adds PMD overhead, Data, and FEC to each burst. The start of each burst is indicated by an arrow pointing to the beginning of the PMD overhead. The diagram is labeled 'Upper layer', 'MAC sublayer', 'PMD sublayer', and 'J.122_F8-2'.](68b20651884fcd557e865537f0803de5_img.jpg)
+
+The diagram illustrates the upstream MAC/PMD convergence process. At the top, the 'Upper layer' is shown. Below it, the 'MAC sublayer' contains three 'MAC frame' blocks. Arrows point from each MAC frame down to the 'PMD sublayer'. In the PMD sublayer, each MAC frame is mapped to a burst of mini-slots. Each burst consists of 'PMD overhead', 'Data', and 'FEC'. Arrows labeled 'Start of burst at mini-slot boundary' point to the beginning of each burst. The diagram is labeled 'J.122\_F8-2' in the bottom right corner.
+
+Diagram illustrating Upstream MAC/PMD convergence. The diagram shows three MAC frames being transmitted from the MAC sublayer to the PMD sublayer. Each MAC frame is mapped to a burst of mini-slots. The PMD sublayer adds PMD overhead, Data, and FEC to each burst. The start of each burst is indicated by an arrow pointing to the beginning of the PMD overhead. The diagram is labeled 'Upper layer', 'MAC sublayer', 'PMD sublayer', and 'J.122\_F8-2'.
+
+**Figure 8-2 – Upstream MAC/PMD convergence**
+
+The layering of MAC frames over MPEG in the downstream channel is described in clause 7.
+
+Note that the CMTS PHY ensures that the CMTS MAC receives upstream MAC frames in the same order the CM mapped the MAC frames onto mini-slots. That is to say that if MAC frame X begins in mini-slot n and MAC frame Y begins in mini-slot n+m, then the CMTS MAC will receive X before it receives Y. This is true even when, as is possible with S-CDMA, mini-slots n and n+m are actually simultaneously transmitted within the PHY layer.
+
+#### 8.2.1.3 Ordering of bits and octets
+
+Within an octet, the least-significant bit is the first transmitted on the wire. This follows the convention used by Ethernet and [ISO/IEC 8802-3]. This is often called bit-little-endian order<sup>7</sup>.
+
+Within the MAC layer, when numeric quantities are represented by more than one octet (i.e., 16-bit and 32-bit values), the octet containing the most-significant bits is the first transmitted on the wire. This is sometimes called byte-big-endian order.
+
+<sup>7</sup> This applies to the upstream channel only. For the downstream channel, the MPEG transmission convergence sublayer presents an octet-wide interface to the MAC, so the MAC sublayer does not define bit order.
+
+This clause follows the textual convention that when bit-fields are presented in tables, the most-significant bits are topmost in the table. For example, in Table 8-2, FC\_TYPE occupies the two most-significant bits and EHDR\_ON occupies the least-significant bit.
+
+##### 8.2.1.3.1 Representing negative numbers
+
+Signed integer values MUST be transmitted and received in two's complement format.
+
+##### 8.2.1.3.2 Type-Length-Value fields
+
+Many MAC messages incorporate type-length-value (TLV) fields. TLV fields are unordered lists of TLV-tuples. Some TLVs are nested (see Annex C). All TLV length fields, except for EH\_LEN (see clause 8.2.6), MUST be greater than zero. Unless otherwise specified, type is one byte and length is one byte.
+
+Using this encoding, new parameters may be added that some devices cannot interpret. A CM or CMTS which does not recognize a parameter type MUST skip over this parameter and MUST NOT treat the event as an error condition.
+
+#### 8.2.1.4 MAC header format
+
+The MAC header format MUST be as shown in Figure 8-3.
+
+![Diagram of MAC header format showing fields FC, MAC_PARM, LEN (SID), EHDR, and HCS, with a detailed view of the FC field bits.](53e80f05e45f132bf76a96442a5507e9_img.jpg)
+
+The diagram illustrates the MAC header format. The main header consists of five fields: FC (1 byte), MAC\_PARM (1 byte), LEN (SID) (2 bytes), EHDR (0-240 bytes), and HCS (2 bytes). The FC field is expanded to show its internal bit structure: FC\_TYPE (2 bits), FC\_PARM (5 bits), and EHDR\_ON (1 bit). Arrows indicate the expansion of the FC field.
+
+|                |                      |                        |                       |                  |
+|----------------|----------------------|------------------------|-----------------------|------------------|
+| FC<br>(1 byte) | MAC_PARM<br>(1 byte) | LEN (SID)<br>(2 bytes) | EHDR<br>(0-240 bytes) | HCS<br>(2 bytes) |
+|----------------|----------------------|------------------------|-----------------------|------------------|
+
+  
+
+|                     |                     |                    |
+|---------------------|---------------------|--------------------|
+| FC_TYPE<br>(2 bits) | FC_PARM<br>(5 bits) | EHDR_ON<br>(1 bit) |
+|---------------------|---------------------|--------------------|
+
+Diagram of MAC header format showing fields FC, MAC\_PARM, LEN (SID), EHDR, and HCS, with a detailed view of the FC field bits.
+
+J.122\_F8-3
+
+**Figure 8-3 – MAC header format**
+
+All MAC headers MUST have the general format as shown in Table 8-1. The frame control (FC) field is the first byte and uniquely identifies the rest of the contents within the MAC header. The FC field is followed by 3 bytes of MAC control; an OPTIONAL extended header (EHDR) field; plus a header check sequence (HCS) to ensure the integrity of the MAC header.
+
+**Table 8-1 – Generic MAC header format**
+
+| MAC header field | Usage                                                                                                                                                                                                                                                  | Size           |
+|------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------|
+| FC               | Frame control: Identifies type of MAC header                                                                                                                                                                                                           | 8 bits         |
+| MAC_PARM         | Parameter field whose use is dependent on FC:<br>if EHDR_ON=1; used for EHDR field length (ELEN)<br>else if for concatenated frames (see Table 8-10) used for MAC frame count<br>else (for requests only) indicates the number of mini-slots requested | 8 bits         |
+| LEN (SID)        | The length of the MAC frame. The length is defined to be the sum of the number of bytes in the extended header (if present) and the number of bytes following the HCS field (for a REQ header, this field is the service ID instead).                  | 16 bits        |
+| EHDR             | Extended MAC header (where present; variable size)                                                                                                                                                                                                     | 0-240 bytes    |
+| HCS              | MAC header check sequence                                                                                                                                                                                                                              | 2 bytes        |
+|                  | Length of a MAC header                                                                                                                                                                                                                                 | 6 bytes + EHDR |
+
+The HCS field is a 16-bit CRC that ensures the integrity of the MAC header, even in a collision environment. The HCS field coverage MUST include the entire MAC header, starting with the FC field and including any EHDR field that may be present. The HCS is calculated using ITU-T CRC ( $x^{16} + x^{12} + x^5 + 1$ ) as defined in [ITU-T X.25].
+
+The FC field is broken down into the FC\_TYPE sub-field, FC\_PARM sub-field and an EHDR\_ON indication flag. The format of the FC field MUST be as shown in Table 8-2.
+
+**Table 8-2 – FC field format**
+
+| FC field | Usage                                                                                                                                          | Size   |
+|----------|------------------------------------------------------------------------------------------------------------------------------------------------|--------|
+| FC_TYPE  | MAC frame control type field:<br>00: Packet PDU MAC header<br>01: ATM PDU MAC header<br>10: Reserved PDU MAC header<br>11: MAC-specific header | 2 bits |
+| FC_PARM  | Parameter bits, use dependent on FC_TYPE                                                                                                       | 5 bits |
+| EHDR_ON  | When = 1, indicates that EHDR field is present.<br>(Length of EHDR (ELEN) determined by MAC_PARM field)                                        | 1 bit  |
+
+The FC\_TYPE sub-field is the two MSBs of the FC field. These bits MUST always be interpreted in the same manner to indicate one of four possible MAC frame formats. These types include: MAC header with packet PDU; MAC header with ATM cells; MAC header reserved for future PDU types; or a MAC header used for specific MAC control purposes. These types are spelled out in more detail in the remainder of this clause.
+
+The five bits following the FC\_TYPE sub-field is the FC\_PARM sub-field. The use of these bits is dependent on the type of MAC header. The LSB of the FC field is the EHDR\_ON indicator. If this bit is set, then an extended header (EHDR) is present. The EHDR provides a mechanism to allow the MAC header to be extensible in an inter-operable manner.
+
+The transmission convergence sublayer stuff-byte pattern is defined to be a value of 0xFF. This precludes the use of FC byte values which have FC\_TYPE = '11' and FC\_PARM = '11111'.
+
+The MAC\_PARM field of the MAC header serves several purposes depending on the FC field. If the EHDR\_ON indicator is set, then the MAC\_PARM field MUST be used as the extended header length (ELEN). The EHDR field may vary from 0 to 240 bytes. If this is a concatenation MAC header, then the MAC\_PARM field represents the number of MAC frames (CNT) in the concatenation (see clause 8.2.5.5). If this is a request MAC header (REQ) (see clause 8.2.5.3), then the MAC\_PARM field represents the amount of bandwidth being requested. In all other cases, the MAC\_PARM field is reserved for future use.
+
+The third field has two possible uses. In most cases, it indicates the length (LEN) of this MAC frame. In one special case, the request MAC header, it is used to indicate the cable modem's service ID since no PDU follows the MAC header.
+
+The extended header (EHDR) field provides extensions to the MAC frame format. It is used to implement data link security as well as frame fragmentation, and can be extended to add support for additional functions in future releases. Initial implementations SHOULD pass this field to the processor. This will allow future software upgrades to take advantage of this capability (refer to clause 8.2.6 for details).
+
+#### 8.2.1.5 Data PDU
+
+The MAC header may be followed by a data PDU. The type and format of the data PDU is defined in the frame control field of the MAC header. The FC field explicitly defines a packet data PDU, an ATM data PDU, a MAC-specific frame and a reserved code point (used as an escape mechanism for future extensions). All CMs MUST use the length in the MAC header to skip over any reserved data.
+
+### 8.2.2 Packet-based MAC frames
+
+#### 8.2.2.1 Variable-length packets
+
+The MAC sublayer MUST support a variable-length Ethernet/[ISO/IEC 8802-3]-type packet data PDU. With the exception of packets that have been subject to payload header suppression, the packet PDU MUST be passed across the network in its entirety, including its original CRC. In the case where payload header suppression has been applied to the packet PDU, all bytes except those suppressed MUST be passed across the network, and the CRC covers only those bytes actually transmitted (refer to clause 8.2.6.3.1). A unique packet MAC header is appended to the beginning. The frame format without an extended header MUST be as shown in Figure 8-4 and Table 8-3.
+
+![Diagram of Ethernet/802.3 packet PDU format showing the MAC header fields and their sub-fields.](1b2ce053624064d94a4143854da46702_img.jpg)
+
+|                |                      |                  |                  |                                         |
+|----------------|----------------------|------------------|------------------|-----------------------------------------|
+| FC<br>(1 byte) | MAC_PARM<br>(1 byte) | LEN<br>(2 bytes) | HCS<br>(2 bytes) | Packet PDU<br>(18-1518 bytes)<br>(Note) |
+|----------------|----------------------|------------------|------------------|-----------------------------------------|
+
+The diagram shows the MAC header structure. The first row contains the main fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Packet PDU (18-1518 bytes). Below the FC field, a dashed line points to a sub-field breakdown: FC\_TYPE = 00, FC\_PARM = 00000, and EHDR\_ON = 0. Below the HCS field, a dashed line points to a sub-field breakdown: DA (6 bytes), SA (6 bytes), Type/len (2 bytes), User data (0-1500 bytes), and CRC (4 bytes).
+
+Diagram of Ethernet/802.3 packet PDU format showing the MAC header fields and their sub-fields.
+
+NOTE – Frame size is limited to 1518 bytes in the absence of VLAN tagging. Cooperating devices which implement IEEE 802.1Q VLAN tagging MAY use a frame size up to 1522 bytes.
+
+J.122\_F8-4
+
+**Figure 8-4 – Ethernet/802.3 packet PDU format**
+
+**Table 8-3 – Packet PDU format**
+
+| Field                   | Usage                                                                                                                                                                                                                                                        | Size            |
+|-------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|
+| FC                      | FC_TYPE = 00; packet MAU header<br>FC_PARM[4:0] = 00000; other values reserved for future use and ignored<br>EHDR_ON = 0 if there is no extended header, 1 if there is an EHDR                                                                               | 8 bits          |
+| MAC_PARM                | MAC_PARM = x; MUST be set to zero if there is no EHDR;<br>Otherwise set to length of EHDR                                                                                                                                                                    | 8 bits          |
+| LEN                     | LEN = n + x; length of packet PDU in bytes + length of EHDR                                                                                                                                                                                                  | 16 bits         |
+| EHDR                    | Extended MAC header, if present                                                                                                                                                                                                                              | x (0-240) bytes |
+| HCS                     | MAC header check sequence                                                                                                                                                                                                                                    | 16 bits         |
+| Packet data, packet PDU | DA – 48-bit destination address<br>SA – 48-bit source address<br>Type/LEN – 16-bit Ethernet type or [ISO/IEC 8802-3] length field<br>User data (variable length, 0-1500 bytes)<br>CRC – 32-bit CRC over packet PDU (as defined in Ethernet/[ISO/IEC 8802-3]) | n bytes         |
+|                         | Length of packet MAC frame                                                                                                                                                                                                                                   | 6 + x + n bytes |
+
+Under certain circumstances (see Appendix VI) it may be necessary to transmit a packet PDU MAC frame without an actual PDU. This is done so that the extended header can be used to carry certain information about the state of the service flow. This could also happen as a result of PHS (see clause 8.2.6.3.1). Such a frame will have the length field in MAC header set to the length of the extended header and will have no packet data, and therefore no CRC. This can only happen with frames transmitted on the upstream as frames transmitted on the downstream always have at least the DA and SA fields of the packet PDU.
+
+### 8.2.3 ATM cell MAC frames
+
+The FC\_TYPE 0x01 is reserved for future definition of ATM cell MAC frames. This FC\_TYPE field in the MAC header indicates that an ATM PDU is present. This PDU MUST be silently discarded by MAC implementations of this version of the Recommendation. Implementations MUST use the length field to skip over the ATM PDU.
+
+### 8.2.4 Reserved PDU MAC frames
+
+The MAC sublayer provides a reserved FC code point to allow for support of future (to be defined) PDU formats. The FC field of the MAC header indicates that a reserved PDU is present. This PDU MUST be silently discarded by MAC implementations of this version of the Recommendation. Implementations compliant to this version of the Recommendation MUST use the length field to skip over the reserved PDU.
+
+The format of the reserved PDU without an extended header MUST be as shown in Figure 8-5 and Table 8-4.
+
+![Diagram of Reserved PDU format showing fields FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Reserved PDU (n bytes). The FC field is expanded to show FC_TYPE = 10, FC_PARM = RRRRR, and EHDR_ON = 0. A label J.122_F8-5 is present.](3349dc82c6333221b0610be6ee7250b6_img.jpg)
+
+J.122\_F8-5
+
+Diagram of Reserved PDU format showing fields FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Reserved PDU (n bytes). The FC field is expanded to show FC\_TYPE = 10, FC\_PARM = RRRRR, and EHDR\_ON = 0. A label J.122\_F8-5 is present.
+
+**Figure 8-5 – Reserved PDU format**
+
+**Table 8-4 – Reserved PDU format**
+
+| Field     | Usage                                                                                                                                               | Size            |
+|-----------|-----------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|
+| FC        | FC_TYPE = 10; reserved PDU MAC header<br>FC_PARM[4:0]; reserved for future use<br>EHDR_ON = 0 if there is no extended header, 1 if there is an EHDR | 8 bits          |
+| MAC_PARM  | MAC_PARM = x; MUST be set to zero if there is no EHDR;<br>Otherwise set to length of EHDR                                                           | 8 bits          |
+| LEN       | LEN = n + x; length of reserved PDU + length of EHDR in bytes                                                                                       | 16 bits         |
+| EHDR      | Extended MAC header, if present                                                                                                                     | x (0-240) bytes |
+| HCS       | MAC header check sequence                                                                                                                           | 16 bits         |
+| User data | Reserved data PDU                                                                                                                                   | n bytes         |
+|           | Length of reserved PDU MAC frame                                                                                                                    | 6 + x + n bytes |
+
+### 8.2.5 MAC-specific headers
+
+There are several MAC headers which are used for very specific functions. These functions include support for downstream timing and upstream ranging/power adjust, requesting bandwidth, fragmentation and concatenating multiple MAC frames.
+
+Table 8-5 describes FC\_PARM usage within the MAC-specific header.
+
+**Table 8-5 – MAC-specific headers and frames**
+
+| FC_PARM | Header/Frame type     |
+|---------|-----------------------|
+| 00000   | Timing header         |
+| 00001   | MAC management header |
+| 00010   | Request frame         |
+| 00011   | Fragmentation header  |
+| 11100   | Concatenation header  |
+
+#### 8.2.5.1 Timing header
+
+A specific MAC header is identified to help support the timing and adjustments required. In the downstream, this MAC header MUST be used to transport the global timing reference to which all cable modems synchronize. In the upstream, this MAC header MUST be used as part of the ranging
+
+message needed for a cable modem's timing and power adjustments. The timing MAC header is followed by a packet data PDU. The format MUST be as shown in Figure 8-6 and Table 8-6.
+
+![Figure 8-6: Timing MAC header diagram. The main header consists of five fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Packet PDU (various lengths). The FC field is expanded to show its internal structure: FC_TYPE = 11, FC_PARM = 00000, and EHDR_ON = 0. The diagram is labeled J.122_F8-6.](207817524fe964425718e1723d5b7d9e_img.jpg)
+
+Figure 8-6: Timing MAC header diagram. The main header consists of five fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and Packet PDU (various lengths). The FC field is expanded to show its internal structure: FC\_TYPE = 11, FC\_PARM = 00000, and EHDR\_ON = 0. The diagram is labeled J.122\_F8-6.
+
+**Figure 8-6 – Timing MAC header**
+
+**Table 8-6 – Timing MAC header format**
+
+| Field       | Usage                                                                                                                                        | Size        |
+|-------------|----------------------------------------------------------------------------------------------------------------------------------------------|-------------|
+| FC          | FC_TYPE = 11; MAC-specific header<br>FC_PARM[4:0] = 00000; timing MAC header<br>EHDR_ON = 0; extended header prohibited for SYNC and RNG-REQ | 8 bits      |
+| MAC_PARM    | Reserved for future use                                                                                                                      | 8 bits      |
+| LEN         | LEN = n; length of packet PDU in bytes                                                                                                       | 16 bits     |
+| EHDR        | Extended MAC header (not present)                                                                                                            | 0 bytes     |
+| HCS         | MAC header check sequence                                                                                                                    | 2 bytes     |
+| Packet data | MAC management message:<br>SYNC message (downstream only)<br>RNG-REQ (upstream only)                                                         | n bytes     |
+|             | Length of timing message MAC frame                                                                                                           | 6 + n bytes |
+
+#### 8.2.5.2 MAC management header
+
+A specific MAC header is identified to help support the MAC management messages required. This MAC header MUST be used to transport all MAC management messages (refer to clause 8.3). The format MUST be as shown Figure 8-7 and Table 8-7.
+
+![Figure 8-7: MAC management header diagram. The main header consists of five fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and MAC mgmt msg (24-1522 bytes). The FC field is expanded to show its internal structure: FC_TYPE = 11, FC_PARM = 00001, and EHDR_ON = 0. The diagram is labeled J.122_F8-7.](235f4d3bfb16ff9c2ab5776a240248a8_img.jpg)
+
+Figure 8-7: MAC management header diagram. The main header consists of five fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), HCS (2 bytes), and MAC mgmt msg (24-1522 bytes). The FC field is expanded to show its internal structure: FC\_TYPE = 11, FC\_PARM = 00001, and EHDR\_ON = 0. The diagram is labeled J.122\_F8-7.
+
+**Figure 8-7 – MAC management header**
+
+**Table 8-7 – MAC management header format**
+
+| Field       | Usage                                                                                                                                                 | Size            |
+|-------------|-------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|
+| FC          | FC_TYPE = 11; MAC-specific header<br>FC_PARM[4:0] = 00001; MAC management header<br>EHDR_ON = 0 if there is no extended header, 1 if there is an EHDR | 8 bits          |
+| MAC_PARM    | MAC_PARM = x; MUST be set to zero if there is no EHDR;<br>Otherwise set to length of EHDR                                                             | 8 bits          |
+| LEN         | LEN = n + x; length of MAC management message + length of<br>EHDR in bytes                                                                            | 16 bits         |
+| EHDR        | Extended MAC header, if present                                                                                                                       | x (0-240) bytes |
+| HCS         | MAC header check sequence                                                                                                                             | 16 bits         |
+| Packet data | MAC management message                                                                                                                                | n bytes         |
+|             | Length of packet MAC frame                                                                                                                            | 6 + x + n bytes |
+
+#### **8.2.5.3 Request frame**
+
+The request frame is the basic mechanism that a cable modem uses to request bandwidth. As such, it is only applicable in the upstream. There MUST be no data PDUs following the request frame. The general format of the request MUST be as shown in Figure 8-8 and Table 8-8.
+
+![Figure 8-8 – Request frame format diagram. The top row shows the frame structure: FC (1 byte), MAC_PARM (1 byte), SID (2 bytes), and HCS (2 bytes). Below the FC field, a breakdown shows its 8 bits: FC_TYPE = 11, FC_PARM = 00010, and EHDR_ON = 0. The diagram is labeled J.122_F8-8.](4b2dd266b605b2f31a8759f802637301_img.jpg)
+
+Figure 8-8 – Request frame format diagram. The top row shows the frame structure: FC (1 byte), MAC\_PARM (1 byte), SID (2 bytes), and HCS (2 bytes). Below the FC field, a breakdown shows its 8 bits: FC\_TYPE = 11, FC\_PARM = 00010, and EHDR\_ON = 0. The diagram is labeled J.122\_F8-8.
+
+**Figure 8-8 – Request frame format**
+
+**Table 8-8 – Request frame (REQ) format**
+
+| Field    | Usage                                                                                                                             | Size    |
+|----------|-----------------------------------------------------------------------------------------------------------------------------------|---------|
+| FC       | FC_TYPE = 11; MAC-specific header<br>FC_PARM[4:0] = 00010; MAC header only; no data PDU following<br>EHDR_ON = 0; no EHDR allowed | 8 bits  |
+| MAC_PARM | REQ; total number of mini-slots requested                                                                                         | 8 bits  |
+| SID      | Service ID used for requesting bandwidth. For valid SID ranges, see clause 9.1.2.                                                 | 16 bits |
+| EHDR     | Extended MAC header not allowed                                                                                                   | 0 bytes |
+| HCS      | MAC header check sequence                                                                                                         | 2 bytes |
+|          | Length of a REQ MAC header                                                                                                        | 6 bytes |
+
+Because the request frame does not have a data PDU following it, the LEN field is not needed. The LEN field MUST be replaced with an SID. The SID MUST uniquely identify a particular service flow within a given CM.
+
+The bandwidth request, REQ, MUST be specified in mini-slots. The REQ field MUST indicate the current total amount of bandwidth requested for this service queue, including appropriate allowance for the PHY overhead.
+
+#### 8.2.5.4 Fragmentation header
+
+The fragmentation MAC header provides the basic mechanism to split a larger MAC PDU into smaller pieces that are transmitted individually and then reassembled at the CMTS. As such, it is only applicable in the upstream. The general format of the fragmentation MAC header MUST be as shown in Figure 8-9.
+
+A compliant CM MUST support fragmentation. A compliant CMTS MUST support fragmentation. To decrease the burden on the CMTS and to reduce unnecessary overhead, fragmentation headers MUST NOT be used on unfragmented frames.
+
+![Figure 8-9: Fragmentation MAC header format diagram. The top row shows the main header fields: FC (1 byte), MAC_PARM (1 byte), LEN (2 bytes), EHDR (6 bytes), HCS (2 bytes), Fragment data, and FCRC (4 bytes). Below FC, MAC_PARM, and EHDR are expanded into their bit-level details. FC is split into FC_TYPE (11), FC_PARM (00011), and EHDR_ON (1). MAC_PARM is split into EHDR_TYPE (0011) and EHDR_LEN (0101). EHDR is split into EHDR_VALUE (5 bytes). A label J.122_F8-9 is present in the bottom right.](a4e9abbc6ca82471f1a223d0a68cd45e_img.jpg)
+
+Figure 8-9: Fragmentation MAC header format diagram. The top row shows the main header fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), EHDR (6 bytes), HCS (2 bytes), Fragment data, and FCRC (4 bytes). Below FC, MAC\_PARM, and EHDR are expanded into their bit-level details. FC is split into FC\_TYPE (11), FC\_PARM (00011), and EHDR\_ON (1). MAC\_PARM is split into EHDR\_TYPE (0011) and EHDR\_LEN (0101). EHDR is split into EHDR\_VALUE (5 bytes). A label J.122\_F8-9 is present in the bottom right.
+
+Figure 8-9 – Fragmentation MAC header format
+
+Table 8-9 – Fragmentation MAC frame (FRAG) format
+
+| Field         | Usage                                                                                                                           | Size         |
+|---------------|---------------------------------------------------------------------------------------------------------------------------------|--------------|
+| FC            | FC_TYPE = 11; MAC-specific header<br>FC_PARM [4:0] = 00011; fragmentation MAC header<br>EHDR_ON = 1; fragmentation EHDR follows | 8 bits       |
+| MAC_PARM      | ELEN = 6 bytes; length of fragmentation EHDR                                                                                    | 8 bits       |
+| LEN           | LEN = length of fragment payload + EHDR length + FCRC length                                                                    | 16 bits      |
+| EHDR          | Refer to clause 8.2.6.2                                                                                                         | 6 bytes      |
+| HCS           | MAC header check sequence                                                                                                       | 2 bytes      |
+| Fragment data | Fragment payload; portion of total MAC PDU being sent                                                                           | n bytes      |
+| FCRC          | CRC – 32-bit CRC over fragment data payload (as defined in Ethernet/[ISO/IEC 8802-3])                                           | 4 bytes      |
+|               | Length of a MAC fragment frame                                                                                                  | 16 + n bytes |
+
+#### 8.2.5.5 Concatenation header
+
+A specific MAC header is defined to allow multiple MAC frames to be concatenated. This allows a single MAC "burst" to be transferred across the network. The PHY overhead<sup>8</sup> and the concatenation MAC header only occur once. Concatenation of multiple MAC frames MUST be as shown in Figure 8-10. Concatenation of multiple MAC frames is the only method by which the CM can transmit more than one MAC frame in a single transmit opportunity.
+
+<sup>8</sup> This includes the preamble, guard time and possibly zero-fill bytes in the last codeword. The FEC overhead recurs for each codeword.
+
+A compliant CM MUST support concatenation. A compliant CMTS MUST support concatenation. Concatenation only applies to upstream traffic. Concatenation MUST NOT be used on downstream traffic.
+
+![](18b914bd6d55df64c6935e65803a3f79_img.jpg)
+
+|              |                   |                                       |  |  |                                       |
+|--------------|-------------------|---------------------------------------|--|--|---------------------------------------|
+| PHY overhead | MAC HDR (concat.) | MAC frame #1 (MAC HDR + optional PDU) |  |  | MAC frame #n (MAC HDR + optional PDU) |
+|--------------|-------------------|---------------------------------------|--|--|---------------------------------------|
+
+J.122\_F8-10
+
+**Figure 8-10 – Concatenation of multiple MAC frames**
+
+Only one concatenation MAC header MUST be present per MAC "burst." Nested concatenation MUST NOT be allowed. Immediately following the concatenation MAC header MUST be the MAC header of the first MAC frame. Information within the MAC header indicates the length of the first MAC frame and provides a means to find the start of the next MAC frame. Each MAC frame within a concatenation MUST be unique and MAY be of any type. This means that packet and MAC-specific frames MAY be mixed together. However, all frames in a concatenation MUST be assigned to the same service flow. The CMTS MUST support concatenations containing multiple frame types, including both packet and MAC-specific frames.
+
+The embedded MAC frames MAY be addressed to different destinations and MUST be delivered as if they were transmitted individually.
+
+The format of the concatenation MAC header MUST be as shown in Figure 8-11 and Table 8-10.
+
+![](8b5a2bf5517051acf8bcc2587bcb73a1_img.jpg)
+
+|             |                   |               |               |
+|-------------|-------------------|---------------|---------------|
+| FC (1 byte) | MAC_PARM (1 byte) | LEN (2 bytes) | HCS (2 bytes) |
+|-------------|-------------------|---------------|---------------|
+
+Diagram showing the breakdown of the FC (1 byte) field:
+
+|              |                 |             |
+|--------------|-----------------|-------------|
+| FC_TYPE = 11 | FC_PARM = 11100 | EHDR_ON = 0 |
+|--------------|-----------------|-------------|
+
+J.122\_F8-11
+
+**Figure 8-11 – Concatenation MAC header format**
+
+**Table 8-10 – Concatenated MAC frame format**
+
+| Field       | Usage                                                                                                                                 | Size          |
+|-------------|---------------------------------------------------------------------------------------------------------------------------------------|---------------|
+| FC          | FC_TYPE = 11; MAC-specific header<br>FC_PARM[4:0] = 11100; concatenation MAC header<br>EHDR_ON = 0; no EHDR with concatenation header | 8 bits        |
+| MAC_PARM    | CNT, number of MAC frames in this concatenation<br>CNT = 0 indicates unspecified number of MAC frames                                 | 8 bits        |
+| LEN         | LEN = x + ... + y; length of all following MAC frames in bytes                                                                        | 16 bits       |
+| EHDR        | Extended MAC header MUST NOT be used                                                                                                  | 0 bytes       |
+| HCS         | MAC header check sequence                                                                                                             | 2 bytes       |
+| MAC frame 1 | First MAC frame: MAC header plus OPTIONAL data PDU                                                                                    | x bytes       |
+| MAC frame n | Last MAC frame: MAC header plus OPTIONAL data PDU                                                                                     | y bytes       |
+|             | Length of concatenated MAC frame                                                                                                      | 6 + LEN bytes |
+
+The MAC\_PARM field in the concatenation MAC header provides a count of MAC frames as opposed to EHDR length or REQ amount as used in other MAC headers. If the field is non-zero, then it MUST indicate the total count of MAC frames (CNT) in this concatenation burst.
+
+### 8.2.6 Extended MAC headers
+
+Every MAC header, except the timing, concatenation MAC header and request frame, has the capability of defining an extended header field (EHDR). The presence of an EHDR field MUST be indicated by the EHDR\_ON flag in the FC field being set. Whenever this bit is set, then the MAC\_PARM field MUST be used as the EHDR length (ELEN). The minimum defined EHDR is 1 byte. The maximum EHDR length is 240 bytes.
+
+A compliant CMTS and CM MUST support extended headers.
+
+The format of a generic MAC header with an extended header included MUST be as shown in Figure 8-12 and Table 8-11.
+
+NOTE – Extended headers MUST NOT be used in a concatenation MAC header, but MAY be included as part of the MAC headers within the concatenation.
+
+Extended headers MUST NOT be used in request frames and timing MAC headers.
+
+![Figure 8-12 – Extended MAC format diagram showing the structure of the MAC header and the internal structure of the EHDR field.](2e83263cd91cb4bcdc0ad2973f715412_img.jpg)
+
+The diagram illustrates the Extended MAC format. The main header consists of six fields: FC (1 byte), MAC\_PARM (1 byte), LEN (2 bytes), EHDR (1-240 bytes), HCS (2 bytes), and Data PDU (optional). The FC field is expanded to show its internal structure: FC\_TYPE (XX), FC\_PARM (reserved), and EHDR\_ON (1). The EHDR field is expanded to show its internal structure: EH\_TYPE (4 bits), EH\_LEN (4 bits), EH\_VALUE (0-15 bytes), and a Repeat indicator. The diagram is labeled J.122\_F8-12.
+
+Figure 8-12 – Extended MAC format diagram showing the structure of the MAC header and the internal structure of the EHDR field.
+
+Figure 8-12 – Extended MAC format
+
+Table 8-11 – Example extended header format
+
+| Field    | Usage                                                                                                                            | Size            |
+|----------|----------------------------------------------------------------------------------------------------------------------------------|-----------------|
+| FC       | FC_TYPE = XX; applies to all MAC headers<br>FC_PARM[4:0] = XXXXX; dependent on FC_TYPE<br>EHDR_ON = 1; EHDR present this example | 8 bits          |
+| MAC_PARM | ELEN = x; length of EHDR in bytes                                                                                                | 8 bits          |
+| LEN      | LEN = x + y; length of EHDR plus OPTIONAL data PDU in bytes                                                                      | 16 bits         |
+| EHDR     | Extended MAC header present this example                                                                                         | x bytes         |
+| HCS      | MAC header check sequence                                                                                                        | 2 bytes         |
+| PDU      | OPTIONAL data PDU                                                                                                                | y bytes         |
+|          | Length of MAC frame with EHDR                                                                                                    | 6 + x + y bytes |
+
+Since the EHDR increases the length of the MAC frame, the LEN field MUST be increased to include both the length of the data PDU and the length of the EHDR.
+
+The EHDR field consists of one or more EH elements. Each EH element is variably sized. The first byte of the EH element MUST contain a type and a length field. Every CM MUST use this length to skip over any unknown EH elements. The format of an EH element MUST be as shown in Table 8-12.
+
+**Table 8-12 – EH element format**
+
+| EH element fields | Usage                 | Size       |
+|-------------------|-----------------------|------------|
+| EH_TYPE           | EH element type field | 4 bits     |
+| EH_LEN            | Length of EH_VALUE    | 4 bits     |
+| EH_VALUE          | EH element data       | 0-15 bytes |
+
+The types of EH element defined in Table 8-13 MUST be supported. Reserved and extended types are undefined at this point and MUST be ignored.
+
+**Table 8-13 – Extended header types**
+
+| EH_TYPE       | EH_LEN | EH_VALUE                                                                                                                                    |
+|---------------|--------|---------------------------------------------------------------------------------------------------------------------------------------------|
+| 0             | 0      | Null configuration setting; may be used to pad the extended header. The EH_LEN MUST be zero, but the configuration setting may be repeated. |
+| 1             | 3      | Request: mini-slots requested (1 byte); SID (2 bytes) [CM → CMTS]                                                                           |
+| 2             | 2      | Acknowledgment requested; SID (2 bytes) [CM → CMTS]                                                                                         |
+| 3 (= BP-UP)   | 4      | Upstream privacy EH element [DOCS8]                                                                                                         |
+|               | 5      | Upstream privacy with fragmentation <sup>a)</sup> EH element [DOCS8] (See clause 8.2.7)                                                     |
+| 4 (= BP-DOWN) | 4      | Downstream privacy EH element [DOCS8]                                                                                                       |
+| 5             | 1      | Service flow EH element; payload header suppression header downstream.                                                                      |
+| 6             | 1      | Service flow EH element; payload header suppression header upstream                                                                         |
+|               | 2      | Service flow EH element; payload header suppression header upstream (1 byte), unsolicited grant synchronization header (1 byte)             |
+| 7-9           |        | Reserved                                                                                                                                    |
+| 10-14         |        | Reserved [CM ↔ CM]                                                                                                                          |
+| 15            | xx     | Extended EH element: EHX_TYPE (1 byte), EHX_LEN (1 byte), EH_VALUE (length determined by EHX_LEN)                                           |
+
+<sup>a)</sup> An upstream privacy with fragmentation EH element MUST only occur within a fragmentation MAC-specific header (refer to clause 8.2.5.4).
+
+The first ten EH element types are intended for one-way transfer between the cable modem and the CMTS. The next five EH element types are for end-to-end usage within a MAC-sublayer domain. Thus, the information attached to EHDR elements 10-14 on the upstream MUST also be attached when the information is forwarded within a MAC-sublayer domain. The final EH element type is an escape mechanism that allows for more types and longer values, and MUST be as shown in Table 8-13.
+
+#### 8.2.6.1 Piggyback requests
+
+Several extended headers can be used to request bandwidth for subsequent transmissions. These requests are generically referred to as "piggyback requests". They are extremely valuable for performance because they are not subject to contention as request frames generally are (refer to clause 9.4).
+
+Requests for additional bandwidth can be included in request, upstream privacy and upstream privacy with fragmentation extended header elements.
+
+#### 8.2.6.2 Fragmentation extended header
+
+Fragmented packets use a combination of the fragmentation MAC header and a modified version of the upstream privacy extended header. Clause 8.2.5.4 describes the fragmentation MAC header. The upstream privacy extended header with fragmentation, also known as the fragmentation extended header, MUST be as shown in Table 8-14.
+
+**Table 8-14 – Fragmentation extended header format**
+
+| EH Element Fields | Usage                                                                           | Size    |
+|-------------------|---------------------------------------------------------------------------------|---------|
+| EH_TYPE           | Upstream privacy EH element = 3                                                 | 4 bits  |
+| EH_LEN            | Length of EH_VALUE = 5                                                          | 4 bits  |
+| EH_VALUE          | Key_seq; same as in BP_UP                                                       | 4 bits  |
+|                   | Ver = 1; version number for this EHDR                                           | 4 bits  |
+|                   | BPI_ENABLE<br>If BPI_ENABLE = 0, BPI disabled<br>If BPI_ENABLE = 1, BPI enabled | 1 bit   |
+|                   | Toggle bit; same as in BP-UP <sup>a)</sup>                                      | 1 bit   |
+|                   | SID; service ID associated with this fragment                                   | 14 bits |
+|                   | REQ; number of mini-slots for a piggyback request                               | 8 bits  |
+|                   | Reserved; must be set to zero                                                   | 2 bits  |
+|                   | First_Frag; set to one for first fragment only                                  | 1 bit   |
+|                   | Last_Frag; set to one for last fragment only                                    | 1 bit   |
+|                   | Frag_seq; fragment sequence count, incremented for each fragment.               | 4 bits  |
+
+<sup>a)</sup> Refer to [DOCS8].
+
+#### 8.2.6.3 Service flow extended header
+
+The service flow EH element is used to enhance service flow operations. It may consist of one or two bytes in the EH\_VALUE field. The payload header suppression header is the only byte in a one-byte field or the first byte in a two-byte field. The unsolicited grant synchronization header is the second byte in a two-byte field.
+
+##### 8.2.6.3.1 Payload header suppression header
+
+In payload header suppression (PHS), a repetitive portion of the payload headers following the HCS is suppressed by the sending entity and restored by the receiving entity. In the upstream, the sending entity is the CM and the receiving entity is the CMTS. In the downstream, the sending entity is the CMTS and the receiving entity is the CM.
+
+For small payloads, payload header suppression provides increased bandwidth efficiency without having to use compression. Payload header suppression may be separately provisioned in the upstream and downstream, and is referenced with an extended header element.
+
+A compliant CM MUST support payload header suppression<sup>9</sup>. A compliant CMTS MUST support payload header suppression.
+
+The payload header suppression extended header sub-element has the format shown in Table 8-15:
+
+<sup>9</sup> This is not intended to imply that the CM must be capable of determining when to invoke payload header suppression. Payload header suppression support is only required for the explicitly signalled case.
+
+**Table 8-15 – Payload header suppression EHDR sub-element format**
+
+| <b>EH element fields</b> | <b>Usage</b>                                                         |                                                           | <b>Size</b> |
+|--------------------------|----------------------------------------------------------------------|-----------------------------------------------------------|-------------|
+| EH_TYPE                  | Service flow EH_TYPE = 5 for downstream and EH_TYPE = 6 for upstream |                                                           | 4 bits      |
+| EH_LEN                   | Length of EH_VALUE = 1                                               |                                                           | 4 bits      |
+| EH_VALUE                 | 0                                                                    | Indicates no payload header suppression on current packet | 8 bits      |
+|                          | 1-255                                                                | Payload header suppression index (PHSI)                   |             |
+
+The payload header suppression index is unique per SID in the upstream and unique per CM in the downstream. Payload header suppression is disabled if this extended header element is omitted or, if included, with the PHSI value set to 0. The payload header suppression index (PHSI) references the suppressed byte string known as a payload header suppression field (PHSF).
+
+NOTE – While PHS signalling allows for up to 255 payload header suppression rules per service flow, the exact number of PHS rules supported per service flow is implementation-dependent. Similarly, PHS signalling allows for PHS sizes of up to 255 bytes, however, the maximum PHS size supported is implementation-dependent. For interoperability, the minimum PHS size that MUST be supported is 64 bytes for any PHS rule supported. As with any other parameter requested in a dynamic service request, a PHS-related DSx request can be denied because of a lack of resources.
+
+The upstream suppression field MUST begin with the first byte following the MAC header checksum. The downstream suppression field MUST begin with the thirteenth byte following the MAC header checksum. This allows the Ethernet SA and DA to be available for filtering by the CM.
+
+The operation of baseline privacy (refer to [DOCS8]) is not affected by the use of PHS. When fragmentation is inactive, baseline privacy begins encryption and decryption with the thirteenth byte following the MAC header checksum.
+
+Unless the entire packet PDU is suppressed, the packet PDU CRC is always transmitted, and MUST be calculated only on the bytes transmitted. The bytes that are suppressed MUST NOT be included in the CRC calculation.
+
+##### **8.2.6.3.2 Unsolicited grant synchronization header**
+
+The unsolicited grant synchronization header may be used to pass status information regarding service flow scheduling between the CM and CMTS. It is currently only defined for use in the upstream with unsolicited grant and unsolicited grant with activity detection scheduling services (refer to clause 10.2.3).
+
+This extended header is similar to the payload suppression EHDR except that the EH\_LEN is 2, and the EH\_VALUE has one additional byte which includes information related to unsolicited grant synchronization. For all other service flow scheduling types, the field SHOULD NOT be included in the extended header element generated by the CM. The CMTS MAY ignore this field.
+
+**Table 8-16 – Unsolicited grant synchronization EHDR sub-element format**
+
+| EH element fields | Usage                    |                                                            | Size                       |
+|-------------------|--------------------------|------------------------------------------------------------|----------------------------|
+| EH_TYPE           | Service flow EH_TYPE = 6 |                                                            | 4 bits                     |
+| EH_LEN            | Length of EH_VALUE = 2   |                                                            | 4 bits                     |
+| EH_VALUE          | 0                        | Indicates no payload header suppression on current packet. | 8 bits<br>(always present) |
+|                   | 1-255                    | Payload header suppression index (PHSI)                    |                            |
+|                   | Queue indicator          |                                                            | 1 bit                      |
+|                   | Active grants            |                                                            | 7 bits                     |
+
+### 8.2.7 Fragmented MAC frames
+
+When enabled, fragmentation is initiated any time the grant length is less than the requested length. This normally occurs because the CMTS chooses to grant less than the requested bandwidth.
+
+![Figure 8-13 – Fragmentation details. This diagram illustrates the structure of MAC frames for single packets and concatenated multiple MAC frames, and then details the fragmentation process. It shows the fields in the MAC header (HDR, EHDR, HCS, PDUs, CRC), the fragmentation header (FC, EHDR, LEN, EHDR), and the structure of individual fragments (FRAG HDR, FHCS, Frag payload, FCRC).](92e26d86c5a582766cb9afdbd2c1aee7_img.jpg)
+
+**Single packet MAC frame**
+
+The diagram shows a single packet MAC frame structure. The MAC HDR is divided into three parts: HDR (containing FC, PARM, and LEN), EHDR (containing PRV and Other), and HCS. The frame also includes a Fragment payload, PDUs, and a CRC.
+
+**Concatenation of multiple MAC Frames**
+
+The diagram shows the concatenation of multiple MAC frames. Each frame consists of a Concat. HDR, MAC HDR1, PDUs, and a CRC. The concatenated frames are followed by a Fragment payload.
+
+**Fragmentation details**
+
+The diagram details the fragmentation process. It shows three fragments (Fragment #1, Fragment #2, and Fragment #3) and a Fragmentation header.
+
+**Fragmentation header structure:**
+
+- FC:** 1B, set to 11 (00011).
+- EHDR:** 1B, LEN = 8.
+- LEN:** 2B, representing the length of the fragment.
+- EHDR:** 6B, containing the following fields:
+  - Ver:** 1B, set to 35.
+  - SID:** 2B, containing the Key sequence number (YYYYY0001).
+  - RQ:** 1B, containing the sequence number (SSSS).
+  - RSV:** 1B, containing the reserved bits (XX).
+
+**Fragment structure:**
+
+- FRAG HDR:** 12 bytes (FHCS).
+- FHCS:** 4 bytes, containing:
+  - F:** Set on first fragment; clear otherwise.
+  - L:** Set on last fragment; clear otherwise.
+  - SSSS:** 4-bit sequence number; increments on each fragment of a packet, rolling over as necessary.
+  - XX:** Reserved; set to 00.
+- Frag payload:** (first, mid, last).
+- FCRC:** 4 bytes, containing:
+  - E:** Enable BPI: 1 = enable, 0 = disable.
+  - T:** Toggle: 1 = odd; 0 = even; Default = 0.
+  - XXXXXXXXXXXXXX:** 14-bit SID.
+
+The encrypted portion for baseline privacy is indicated for each fragment.
+
+Figure 8-13 – Fragmentation details. This diagram illustrates the structure of MAC frames for single packets and concatenated multiple MAC frames, and then details the fragmentation process. It shows the fields in the MAC header (HDR, EHDR, HCS, PDUs, CRC), the fragmentation header (FC, EHDR, LEN, EHDR), and the structure of individual fragments (FRAG HDR, FHCS, Frag payload, FCRC).
+
+J.122\_F8-13
+
+**Figure 8-13 – Fragmentation details**
+
+The CM MAC calculates how many bytes of the original frame, including overhead for a fragmentation header and CRC, can be sent in the received grant. The CM MAC generates a fragmentation header for each fragment. Fragmented frames use the MAC message type (FC = 11). The FC parameter field is set to (00011), in order to uniquely identify the fragmentation header from other MAC message types. A four bit sequence field is used in the last byte of the extended header field to aid in reassembly and to detect dropped or missing fragments. The CM arbitrarily
+
+selects a sequence number for the first fragment of a frame<sup>10</sup>. Once the sequence number is selected for the first fragment, the CM MUST increment the sequence number by one for each fragment transmitted for that frame. There are two flags associated with the sequence number, F and L, where F is set to indicate the first fragment and L is set to indicate the last fragment. Both are cleared for middle fragments. The CMTS stores the sequence number of the first fragment (F bit set) of each frame. The CMTS MUST verify that the fragment sequence field increments (by one) for each fragment of the frame.
+
+The REQ field in the fragmentation header is used by the fragmentation protocol for first and middle fragments (refer to clause 10.3). For the last fragment, the REQ field is interpreted as a request for bandwidth for a subsequent frame.
+
+Fragmentation headers are fixed size and MUST contain only a fragmentation extended header element. The extended header consists of a privacy EH element extended by one byte to make the fragment overhead an even 16 bytes. A privacy EH element is used whether the original packet header contained a privacy EH element or not. If privacy is in use, the following fields, version, enable bit and SID, in the fragment EH element are the same with those of BP EH element inside the original MAC frame. If privacy is not in use, the privacy EH element is used but the enable bit is cleared. The SID used in the fragment EH element MUST match the SID used in the partial grant that initiated the fragmentation. A separate CRC MUST be calculated for each fragment (note that each MAC frame payload will also contain the CRC for that packet). A packet CRC of a reassembled packet MAY be checked by the CMTS even though an FCRC covers each fragment.
+
+The CMTS MUST make certain that any fragmentary grant it makes is large enough to hold at least 17 bytes of MAC layer data. This is to ensure that the grant is large enough to accommodate fragmentation overhead plus at least 1 byte of actual data. The CMTS may want to enforce an even higher limit as small fragments are extremely inefficient.
+
+When fragmentation is active, baseline privacy encryption and decryption begin with the first byte following the MAC header checksum.
+
+#### **8.2.7.1 Considerations for concatenated packets and fragmentation**
+
+MAC management messages and data PDUs can occur in the same concatenated frame. Without fragmentation, the MAC management messages within a concatenated frame would be unencrypted. However, with fragmentation enabled on the concatenated frame, the entire concatenated frame is encrypted based on the privacy extended header element. This allows baseline privacy to encrypt each fragment without examining its contents. Clearly, this only applies when baseline privacy is enabled.
+
+To ensure encryption synchronization, if fragmentation, concatenation and baseline privacy are all enabled, a CM MUST NOT concatenate BPKM MAC management messages. This ensures that BPKM MAC management messages are always sent unencrypted.
+
+### **8.2.8 Error-handling**
+
+The cable network is a potentially harsh environment that can cause several different error conditions to occur. This clause, together with clause 11.5, describes the procedures that are required when an exception occurs at the MAC framing level.
+
+The most obvious type of error occurs when the HCS on the MAC header fails. This can be a result of noise on the network or possibly by collisions in the upstream channel. Framing recovery on the downstream channel is performed by the MPEG transmission convergence sublayer. In the upstream channel, framing is recovered on each transmitted burst, such that framing on one burst is
+
+---
+
+<sup>10</sup> 'Frame' always refers to either frames with a single packet PDU or concatenated frame.
+
+independent of framing on prior bursts. Hence, framing errors within a burst are handled by simply ignoring that burst; i.e., errors are unrecoverable until the next burst.
+
+A second exception, which applies only to the upstream, occurs when the length field is corrupted and the MAC thinks the frame is longer or shorter than it actually is. Synchronization will recover at the next valid upstream data interval.
+
+For every MAC transmission, The HCS MUST be verified. When a bad HCS is detected, the MAC header and any payload MUST be dropped.
+
+For packet PDU transmissions, a bad CRC may be detected. Since the CRC only covers the data PDU and the HCS covers the MAC Header; the MAC header is still considered valid. Thus, the packet PDU MUST be dropped, but any pertinent information in the MAC header (e.g., bandwidth request information) MAY be used.
+
+#### **8.2.8.1 Error recovery during fragmentation**
+
+There are some special error handling considerations for fragmentation. Each fragment has its own fragmentation header complete with an HCS and its own FCRC. There may be other MAC headers and CRCs within the fragmented payload. However, only the HCS of the fragment header and the FCRC are used for error detection during fragment reassembly.
+
+If the HCS for a fragment fails, the CMTS MUST discard that fragment. If the HCS passes but the FCRC fails, the CMTS MUST discard that fragment, but MAY process any requests in the fragment header. The CMTS SHOULD process such a request if it is performing fragmentation in piggyback mode (refer to clause 10.3.2.2). This allows the remainder of the frame to be transmitted as quickly as possible.
+
+If a CMTS is performing fragmentation in multiple grant mode (refer to clause 10.3.2.1) it SHOULD complete all the grants necessary to fulfil the CM's original request even if a fragment is lost or discarded. This allows the remainder of the frame to be transmitted as quickly as possible.
+
+If any fragment of a non-concatenated MAC frame is lost or discarded, the CMTS MUST discard the rest of that frame. If a fragment of a concatenated MAC frame is lost or discarded, the CMTS MAY forward any frames within the concatenation that have been received correctly or it MAY discard all the frames in the concatenation.
+
+A CMTS MUST terminate fragment reassembly if any of the following occurs for any fragment on a given SID:
+
+- The CMTS receives a fragment with the L-bit set.
+- The CMTS receives an upstream fragment, other than the first one, with the F-bit set.
+- The CMTS receives a packet PDU frame with no fragmentation header.
+- The CMTS deletes the SID for any reason.
+
+In addition, the CMTS MAY terminate fragment reassembly based on implementation-dependent criteria such as a reassembly timer. When a CMTS terminates fragment reassembly, it MUST dispose of (either by discarding or forwarding) the reassembled frame(s).
+
+#### **8.2.8.2 Error codes and messages**
+
+Annex D of [DOCS5] lists CM and CMTS error codes and messages. When reporting error conditions, these codes MUST be used as indicated in [DOCS5] and MAY be used for reporting errors via vendor-specific interfaces. If the error codes are used, the error messages MAY be replaced by other descriptive messages.
+
+## 8.3 MAC management messages
+
+### 8.3.1 MAC management message header
+
+MAC management messages MUST be encapsulated in an LLC unnumbered information frame per [ISO/IEC 8802-2], which in turn is encapsulated within the cable network MAC framing, as shown in Figure 8-14. Figure 8-14 shows the MAC header and the MAC management message header fields which are common across all MAC management messages.
+
+![Diagram of MAC header and MAC management message header fields. The diagram shows a sequence of fields in a frame, with bit positions 0, 8, 16, 24, and 31 marked at the top. The fields are grouped into the MAC header (FC, MAC PARM, LEN, HCS) and the MAC management message header (DA, DA, SA, Msg LEN, DSAP, SSAP, Control, Version, Type, RSVD). The Management message payload and CRC follow. Labels on the right indicate the MAC header, MAC management message header, and the payload.](921f8fa0f7ce2c9956f20d33162c13a2_img.jpg)
+
+|     |                            |          |      |      |    |
+|-----|----------------------------|----------|------|------|----|
+| Bit | 0                          | 8        | 16   | 24   | 31 |
+|     | FC                         | MAC PARM | LEN  |      |    |
+|     | HCS                        |          |      |      |    |
+|     | DA                         |          |      |      |    |
+|     | DA                         |          | SA   |      |    |
+|     | SA                         |          |      |      |    |
+|     | Msg LEN                    |          | DSAP | SSAP |    |
+|     | Control                    | Version  | Type | RSVD |    |
+|     | Management message payload |          |      |      |    |
+|     | CRC                        |          |      |      |    |
+
+J.122\_F8-14
+
+Diagram of MAC header and MAC management message header fields. The diagram shows a sequence of fields in a frame, with bit positions 0, 8, 16, 24, and 31 marked at the top. The fields are grouped into the MAC header (FC, MAC PARM, LEN, HCS) and the MAC management message header (DA, DA, SA, Msg LEN, DSAP, SSAP, Control, Version, Type, RSVD). The Management message payload and CRC follow. Labels on the right indicate the MAC header, MAC management message header, and the payload.
+
+Figure 8-14 – MAC header and MAC management message header fields
+
+The fields MUST be as defined below:
+
+- **FC, MAC PARM, LEN, HCS:** Common MAC frame header (refer to clause 8.2.1.4 for details). All messages use a MAC-specific header.
+- **Destination address (DA):** MAC management frames will be addressed to a specific CM unicast address or to the DOCS management multicast address. These DOCS MAC management addresses are described in Annex A.
+- **Source address (SA):** The MAC address of the source CM or CMTS system.
+- **Msg LEN:** Length of the MAC message from DSAP to the end of the payload.
+- **DSAP:** The LLC null destination SAP (00) as defined by [ISO/IEC 8802-2].
+- **SSAP:** The LLC null source SAP (00) as defined by [ISO/IEC 8802-2].
+- **Control:** Unnumbered information frame (03) as defined by [ISO/IEC 8802-2].
+- **Version and Type:** Each 1 octet. Refer to Table 8-17. Messages with a version number of 1 are understood by all CMs and CMTSs compliant with all versions of the DOCS Recommendation. Messages with a version number of 2 are understood by DOCS 1.1 and 2.0 equipment, and messages with a version number of 3 are understood by DOCS 2.0
+
+equipment. DOCS 2.0-compliant CMs and CMTSs MUST silently discard any message with a version number greater than 3.
+
+**Table 8-17 – MAC management message types**
+
+| Type value | Version | Message name | Message description                                                                                                                                                          |
+|------------|---------|--------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 1          | 1       | SYNC         | Timing synchronization                                                                                                                                                       |
+| 2 or 29    | 1 or 3  | UCD          | Upstream channel descriptor<br>A UCD for a DOCS 2.0-only channel uses a type of 29 and a version of 3. All other UCDs use a type of 2 and a version of 1 (see clause 8.3.3). |
+| 3          | 1       | MAP          | Upstream bandwidth allocation                                                                                                                                                |
+| 4          | 1       | RNG-REQ      | Ranging request                                                                                                                                                              |
+| 5          | 1       | RNG-RSP      | Ranging response                                                                                                                                                             |
+| 6          | 1       | REG-REQ      | Registration request                                                                                                                                                         |
+| 7          | 1       | REG-RSP      | Registration response                                                                                                                                                        |
+| 8          | 1       | UCC-REQ      | Upstream channel change request                                                                                                                                              |
+| 9          | 1       | UCC-RSP      | Upstream channel change response                                                                                                                                             |
+| 10         | 1       | TRI-TCD      | Telephony channel descriptor – [DOCS6]                                                                                                                                       |
+| 11         | 1       | TRI-TSI      | Termination system information – [DOCS6]                                                                                                                                     |
+| 12         | 1       | BPKM-REQ     | Privacy key management request [DOCS8]                                                                                                                                       |
+| 13         | 1       | BPKM-RSP     | Privacy key management response [DOCS8]                                                                                                                                      |
+| 14         | 2       | REG-ACK      | Registration acknowledgement                                                                                                                                                 |
+| 15         | 2       | DSA-REQ      | Dynamic service addition request                                                                                                                                             |
+| 16         | 2       | DSA-RSP      | Dynamic service addition response                                                                                                                                            |
+| 17         | 2       | DSA-ACK      | Dynamic service addition acknowledgement                                                                                                                                     |
+| 18         | 2       | DSC-REQ      | Dynamic service change request                                                                                                                                               |
+| 19         | 2       | DSC-RSP      | Dynamic service change response                                                                                                                                              |
+| 20         | 2       | DSC-ACK      | Dynamic service change acknowledgement                                                                                                                                       |
+| 21         | 2       | DSD-REQ      | Dynamic service deletion request                                                                                                                                             |
+| 22         | 2       | DSD-RSP      | Dynamic service deletion response                                                                                                                                            |
+| 23         | 2       | DCC-REQ      | Dynamic channel change request                                                                                                                                               |
+| 24         | 2       | DCC-RSP      | Dynamic channel change response                                                                                                                                              |
+| 25         | 2       | DCC-ACK      | Dynamic channel change acknowledgement                                                                                                                                       |
+| 26         | 2       | DCI-REQ      | Device class identification request                                                                                                                                          |
+| 27         | 2       | DCI-RSP      | Device class identification response                                                                                                                                         |
+| 28         | 2       | UP-DIS       | Upstream transmitter disable                                                                                                                                                 |
+| 29         | 3       |              | (See entry for UCD)                                                                                                                                                          |
+| 30         | 3       | INIT-RNG-REQ | Initial ranging request                                                                                                                                                      |
+| 31         | 3       | TST-REQ      | Test request message                                                                                                                                                         |
+| 32         | 3       | DCD          | Downstream channel descriptor (DSG)                                                                                                                                          |
+| 33-255     |         |              | Reserved for future use                                                                                                                                                      |
+
+- **RSVD:** 1 octet. This field is used to align the message payload on a 32-bit boundary. Set to 0 for this version for all messages other than the RNG-REQ and INIT-RNG-REQ. See clauses 8.3.5 and 8.3.26 for setting this value for these two messages.
+- **Management message payload:** Variable length. As defined for each specific management message.
+- **CRC:** Covers message including header fields (DA, SA, ...). Polynomial defined by [ISO/IEC 8802-3].
+
+A compliant CMTS or CM MUST support the MAC management message types listed in Table 8-17, except messages specific to telephony return devices which MAY be supported.
+
+### 8.3.2 Time synchronization (SYNC)
+
+Time synchronization (SYNC) MUST be transmitted by CMTS at a periodic interval to establish MAC sublayer timing. This message MUST use an FC field with FC\_TYPE = MAC-specific header and FC\_PARM = timing MAC header. This MUST be followed by a packet PDU in the format shown in Figure 8-15.
+
+![Diagram of packet PDU following the timing header. It shows a 32-bit structure with Bit 0, 8, 16, 24, and 31 marked at the top. The top portion is the 'MAC management message header' and the bottom portion is the 'CMTS timestamp'. There are break symbols on the left and right sides of the header section.](649f424fd35ea31f622163506a6148ed_img.jpg)
+
+J.122\_F8-15
+
+Diagram of packet PDU following the timing header. It shows a 32-bit structure with Bit 0, 8, 16, 24, and 31 marked at the top. The top portion is the 'MAC management message header' and the bottom portion is the 'CMTS timestamp'. There are break symbols on the left and right sides of the header section.
+
+**Figure 8-15 – Format of packet PDU following the timing header**
+
+The parameters shall be as defined below:
+
+- **CMTS timestamp:** The count state of an incrementing 32-bit binary counter clocked with the CMTS 10.24-MHz master clock.
+
+The CMTS timestamp represents the count state at the instant that the first byte (or a fixed time offset from the first byte) of the time synchronization MAC management message is transferred from the downstream transmission convergence sublayer to the downstream physical media dependent sublayer as described in clause 6.3.7. The CMTS MUST NOT allow a SYNC message to cross an MPEG packet boundary<sup>11</sup>.
+
+### 8.3.3 Upstream channel descriptor (UCD)
+
+An upstream channel descriptor MUST be transmitted by the CMTS at a periodic interval to define the characteristics of an logical upstream channel (see Figure 8-16). A separate message MUST be transmitted for each logical upstream that is currently available for use.
+
+<sup>11</sup> Since the SYNC message applies to all upstream channels within this MAC domain, units were chosen to be independent of the modulation rate of any particular upstream channel. See clause 9.3.4 for time-unit relationships.
+
+![Diagram of the Upstream channel descriptor message structure. The message is 32 bits long (bits 0 to 31). The first 16 bits (bits 0-15) are the MAC management message header. The next 16 bits (bits 16-31) are divided into four 4-bit nibbles: Upstream channel ID (bits 16-19), Configuration change count (bits 20-23), Mini-slot size (bits 24-27), and Downstream channel ID (bits 28-31). Below these nibbles are three TLV-encoded information fields: 'TLV-encoded information for the overall channel', 'TLV-encoded burst description', and 'TLV-encoded information for the subsequent burst descriptors'. The diagram is labeled J.122_F8-16.](4ef412e08808c40e0beb7808d36b9379_img.jpg)
+
+|                                                              |                            |                |                       |
+|--------------------------------------------------------------|----------------------------|----------------|-----------------------|
+| Bit 0 8 16 24 31                                             |                            |                |                       |
+| MAC management message header                                |                            |                |                       |
+| Upstream channel ID                                          | Configuration change count | Mini-slot size | Downstream channel ID |
+| TLV-encoded information for the overall channel              |                            |                |                       |
+| TLV-encoded burst description                                |                            |                |                       |
+| TLV-encoded information for the subsequent burst descriptors |                            |                |                       |
+
+J.122\_F8-16
+
+Diagram of the Upstream channel descriptor message structure. The message is 32 bits long (bits 0 to 31). The first 16 bits (bits 0-15) are the MAC management message header. The next 16 bits (bits 16-31) are divided into four 4-bit nibbles: Upstream channel ID (bits 16-19), Configuration change count (bits 20-23), Mini-slot size (bits 24-27), and Downstream channel ID (bits 28-31). Below these nibbles are three TLV-encoded information fields: 'TLV-encoded information for the overall channel', 'TLV-encoded burst description', and 'TLV-encoded information for the subsequent burst descriptors'. The diagram is labeled J.122\_F8-16.
+
+**Figure 8-16 – Upstream channel descriptor**
+
+The MAC management header for this message has 2 possible values for the type field and for the version field. For DOCS 2.0-only upstreams the CMTS MUST use a value of 29 for the type field and MUST use a value of 3 for the version field. For all other logical upstreams, the CMTS MUST use a value of 2 for the type field and a value of 1 for the version field. A CMTS MUST NOT use type 5 TLVs to encode IUCs 1-6 in a UCD with a message type of 2. A CMTS MUST use type 5 TLVs to encode all burst profiles in a UCD with a message type of 29.
+
+A type 2 UCD MUST contain type 4 burst descriptors for IUCs 3 and 4, a type 4 burst descriptor for requests and a type 4 burst descriptor for data. The burst descriptors for requests and data MUST use 1.x TDMA. To describe a 1.x/2.0 mixed logical channel, the UCD MUST additionally contain a type 5 burst descriptor for 2.0 TDMA data opportunities.
+
+A type 29 UCD MUST contain a type 5 burst descriptor for IUC 3, a type 5 burst descriptor for requests, and a type 5 burst descriptor for data.
+
+A CMTS MUST NOT include burst descriptors for IUCs 5 or 6 in a UCD message for a DOCS 2.0-only upstream.
+
+For interoperability, a CMTS SHOULD provide:
+
+- burst descriptors for IUCs 1, 5 and 6 in a type 2 UCD describing a 1.x-only channel;
+- burst descriptors for IUCs 1, 5, 6, 9 and 10 in a type 2 UCD describing a 1.x/2.0 mixed logical channel;
+- burst descriptors for IUCs 1, 9 and 10 in a type 29 UCD.
+
+The CMTS MUST treat an upstream as a DOCS 2.0-only upstream if any of the following is true about the channel wide parameters: S-CDMA mode is enabled, the mini-slot size is 1 time tick, or the value of the modulation rate parameter is 32. The CMTS MUST treat an upstream as a DOCS 2.0-only upstream if any of the following is true about any of IUCs 1-4: A modulation type other than QPSK or 16QAM is used, the FEC error correction (T) parameter is greater than 10, any portion of the extended preamble is used, any attribute from Table 8-19, "upstream physical-layer burst attributes," with a type greater than 11 is present in the descriptor. Note that none of these conditions can ever be true for IUCs 5 or 6.
+
+To provide for flexibility, the message parameters following the channel ID MUST be encoded in a type/length/value (TLV) form in which the type and length fields are each 1 octet long.
+
+A CMTS MUST generate UCDs in the format shown in Figure 8-16, including all of the following parameters:
+
+- **Configuration change count:** Incremented by one (modulo the field size) by the CMTS whenever any of the values of this channel descriptor change, excluding the S-CDMA snapshot TLV<sup>12</sup>. If the value of this count in a subsequent UCD remains the same, the CM can quickly decide that the channel operating parameters have not changed, and may be able to disregard the remainder of the message. This value is also referenced from the MAP.
+- **Mini-slot size:** The size T of the mini-slot for this upstream channel in units of the timebase tick of 6.25 µs. For channels that can support DOCS 1.x CMs, the allowable values are  $T = 2^M$ ,  $M = 1, \dots, 7$ . That is,  $T = 2, 4, 8, 16, 32, 64$  or  $128$ .
+
+For DOCS 2.0-only channels, the relationship between M and T remains the same, but the allowable values are  $M = 0, 1, \dots, 7$ , with  $T = 1, 2, 4, 8, 16, 32, 64$  or  $128$ . If the value of T is 1 then the channel MUST be treated as a DOCS 2.0-only channel. On S-CDMA channels, this parameter will not have any effect.
+
+- **Upstream channel ID:** The identifier of the upstream channel to which this message refers. This identifier is arbitrarily chosen by the CMTS and is only unique within the MAC-sublayer domain.
+
+NOTE – Upstream channel ID = 0 is reserved to indicate telephony return.
+
+- **Downstream channel ID:** The identifier of the downstream channel on which this message has been transmitted. This identifier is arbitrarily chosen by the CMTS at startup, and is only unique within the MAC-sublayer domain.
+
+All other parameters are coded as TLV tuples. The type values used MUST be those defined in Table 8-18, for channel parameters, and Table 8-19, for upstream physical layer burst attributes. Burst descriptors (type 4 and/or type 5) MUST appear in the UCD message after all other channel-wide parameters.
+
+**Table 8-18 – Channel TLV parameters**
+
+| Name            | Type<br>(1 byte) | Length<br>(1 byte) | Value<br>(variable length)                                                                                                                                                                                      |
+|-----------------|------------------|--------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Modulation rate | 1                | 1                  | Multiples of base rate of 160 kHz (value is 1, 2, 4, 8, 16, or 32). A value of 32 means that this is a DOCS 2.0-only upstream. If S-CDMA mode is enabled, then this parameter MUST have a value of 8, 16 or 32. |
+| Frequency       | 2                | 4                  | Upstream centre frequency (Hz)                                                                                                                                                                                  |
+
+<sup>12</sup> Refer to clause 6.2.11.2 for a description of the timestamp snapshot. The periodic update of the snapshot association does not represent a change in the operating parameters of the channel, hence the UCD configuration change count will not be incremented.
+
+**Table 8-18 – Channel TLV parameters**
+
+| Name                                 | Type<br>(1 byte) | Length<br>(1 byte) | Value<br>(variable length)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
+|--------------------------------------|------------------|--------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Preamble pattern                     | 3                | 1-128              | <p>The value field defines the first portion of the preamble superstring. If there is no extended preamble pattern parameter, then this parameter defines the entire preamble superstring. All burst-specific preamble values are chosen as bit-substrings of the preamble superstring.</p> <p>The first byte of the value field contains the first 8 bits of the superstring, with the first bit of the preamble superstring in the MSB position of the first value field byte, the eighth bit of the preamble superstring in the LSB position of the first value field byte; the second byte in the value field contains the second eight bits of the superstring, with the ninth bit of the superstring in the MSB of the second byte and sixteenth bit of the preamble superstring in the LSB of the second byte, and so forth.</p> |
+| Burst descriptor (DOCS 1.x)          | 4                | n                  | May appear more than once; described below.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
+| Burst descriptor (DOCS 2.0)          | 5                | n                  | May appear more than once; described below.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
+| Extended preamble pattern            | 6                | 1-64               | <p>512-bit preamble superstring extension.</p> <p>The value field is concatenated to the end of the value field of the preamble pattern to complete the preamble superstring. This parameter MUST NOT be included unless the length of the preamble pattern parameter is 128 bytes. Therefore, the MSB of the first byte of the value field of this parameter always follows the LSB of the 128th byte of the value field of the preamble pattern parameter in the preamble superstring.</p>                                                                                                                                                                                                                                                                                                                                            |
+| S-CDMA mode enable <sup>a)</sup>     | 7                | 1                  | 1 = on; 2 = off. If parameter is on, the upstream will operate in S-CDMA mode. Otherwise, it operates in TDMA mode. If this parameter is set to on, this is a DOCS 2.0-only upstream.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
+| S-CDMA spreading intervals per frame | 8                | 1                  | <p>Number of consecutive spreading intervals mapped onto a two-dimensional frame (value is 1 through 32).</p> <p>This TLV MUST be present if S-CDMA mode is enabled, and MUST NOT be present if it is not.</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
+| S-CDMA codes per mini-slot           | 9                | 1                  | <p>Number of consecutive codes mapped into a two-dimensional mini-slot (value is 2 through 32).</p> <p>This TLV MUST be present if S-CDMA mode is enabled, and MUST NOT be present if it is not.</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+| S-CDMA number of active codes        | 10               | 1                  | <p>Number of codes available to carry data payload (value is 64 through 128). This value MUST be a multiple of codes per mini-slot (TLV type 9).</p> <p>This TLV MUST be present if S-CDMA Mode is enabled, and MUST NOT be present if it is not.</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
+| S-CDMA code-hopping seed             | 11               | 2                  | <p>15-bit seed to initialize code-hopping sequence. The value is left-justified in the 2-byte field. Set seed = 0 to disable code hopping.</p> <p>This TLV MUST be present if S-CDMA Mode is enabled, and MUST NOT be present if it is not.</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+
+**Table 8-18 – Channel TLV parameters**
+
+| Name                                    | Type<br>(1 byte) | Length<br>(1 byte) | Value<br>(variable length)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
+|-----------------------------------------|------------------|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| S-CDMA US ratio numerator "M"           | 12               | 2                  | The numerator (M) of the M/N ratio relating the downstream symbol clock to the upstream modulation clock.<br><br>This TLV MUST be present if S-CDMA mode is enabled, and MUST NOT be present if it is not.                                                                                                                                                                                                                                                                                                                                 |
+| S-CDMA US ratio denominator "N"         | 13               | 2                  | The denominator (N) of the M/N ratio relating the downstream symbol clock to the upstream modulation clock.<br><br>This TLV MUST be present if S-CDMA mode is enabled, and MUST NOT be present if it is not.                                                                                                                                                                                                                                                                                                                               |
+| S-CDMA timestamp snapshot <sup>b)</sup> | 14               | 9                  | Snapshot of the timestamp, mini-slot and S-CDMA frame taken at an S-CDMA frame boundary at the CMTS. A new value MUST be sampled and sent with each UCD message. Refer to clause 6.2.11.2, "mini-slot numbering".<br><br>This TLV MUST be present if S-CDMA mode is enabled, and MUST NOT be present if it is not.                                                                                                                                                                                                                         |
+| Maintain power spectral density         | 15               | 1                  | 1 = on; 2 = off. If this value is on and the modulation rate is different from the previous UCD, the CM MUST change its transmit power level to keep the power spectral density as close as possible to what it was prior to the modulation rate change. If this value is off or this parameter is omitted then the CM maintains the same power level that it was using prior to the modulation rate change.<br><br>In any case the effect of this parameter only lasts until the CM receives a power adjustment in a RNG-RSP.             |
+| Ranging required                        | 16               | 1                  | 0 = no ranging required;<br>1 = unicast initial ranging required;<br>2 = broadcast initial ranging required.<br><br>If this value is non-zero and the UCD change count does not match the UCD currently in effect, the CM MUST perform ranging as specified by this TLV before using any other transmit opportunities with the new UCD parameters. If ranging is required, and the CM is already registered, then it MUST maintain its SIDs and not re-register.<br><br>If this value is 0 or this TLV is omitted, no ranging is required. |
+| S-CDMA maximum scheduled codes enabled  | 17               | 1                  | 1 = maximum scheduled codes is enabled 2 = maximum scheduled codes is disabled. CMs that implement the S-CDMA maximum scheduled codes MUST set the RSVD field in the ranging requests as described in clauses 8.3.5 and 8.3.26. If S-CDMA mode is disabled on this channel, this TLV MUST NOT be present.                                                                                                                                                                                                                                  |
+| Ranging hold-off priority field         | 18               | 4                  | Bit field with values representing device classes, as defined in clause C.1.3.1.16 that should temporarily inhibit initial ranging. The CMTS MAY include this TLV in the UCD message. The CM MUST observe this TLV, as described in clause 11.2.2.                                                                                                                                                                                                                                                                                         |
+
+**Table 8-18 – Channel TLV parameters**
+
+| Name                                                                                                                                                                                                                                                                                                                                                    | Type (1 byte) | Length (1 byte) | Value (variable length)                                                                                                                                                                                                               |
+|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|-----------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Channel class ID                                                                                                                                                                                                                                                                                                                                        | 19            | 4               | Bit field with values representing device classes as defined in clause C.1.3.1.16 that are allowed to use the channel. The CMTS MAY include this TLV in the UCD message. The CM MUST observe this TLV, as described in clause 11.2.2. |
+| a) CM MUST assume S-CDMA mode is off if TLV is not present.<br>b) Refer to clause 6.2.11.2, "mini-slot numbering", for a description of the timestamp snapshot. A change solely in this parameter for a particular UCD does not represent a change in overall channel operating parameters, hence the UCD channel change count will not be incremented. |               |                 |                                                                                                                                                                                                                                       |
+
+Burst descriptors are composed of an upstream interval usage code, followed by TLV encodings that define, for each type of upstream usage interval, the physical-layer characteristics that are to be used during that interval. The upstream interval usage codes are defined in the MAP message (see clause 8.3.4 and Table 8-20). The format of the burst descriptors is shown in Figure 8-17.
+
+![Figure 8-17: Top-level encoding for burst descriptors. The diagram shows a 32-bit word structure. Bits 0-7 are 'Type = 4 or 5 burst descriptor'. Bits 8-15 are 'Length (n)'. Bits 16-23 are 'Interval usage code'. Bits 24-31 are 'TLV codes for PHY parameters (n - 1)'. The diagram uses a dashed box for the variable-length TLV section.](fa1eb5ed4fcf8f8d184ead2a8a5a08e6_img.jpg)
+
+Figure 8-17: Top-level encoding for burst descriptors. The diagram shows a 32-bit word structure. Bits 0-7 are 'Type = 4 or 5 burst descriptor'. Bits 8-15 are 'Length (n)'. Bits 16-23 are 'Interval usage code'. Bits 24-31 are 'TLV codes for PHY parameters (n - 1)'. The diagram uses a dashed box for the variable-length TLV section.
+
+**Figure 8-17 – Top-level encoding for burst descriptors**
+
+In Figure 8-17:
+
+- **Type:** 4 for burst descriptors intended for DOCS 1.x and/or DOCS 2.0 modems. 5 is for burst descriptors intended for DOCS 2.0 modems only.
+- **Length:** The number of bytes in the overall object, including the IUC and the embedded TLV items.
+- **IUC:** Interval usage code defined in Table 8-20. The IUC is coded on the 4 least-significant bits. The four most-significant bits are unused (=0).
+- **TLV items:** TLV parameters described in Table 8-18, "channel TLV parameters".
+
+Two different type values are used to describe burst descriptors. Type 4 burst descriptors MUST be understood by all modems and MUST only be used to describe IUCs 1 through 6 from Table 8-20. Type 5 burst descriptors MUST be understood by DOCS 2.0 modems. A type 5 burst descriptor MUST be used to describe any IUC if any of the following is true: a modulation type other than QPSK or 16QAM is used, the FEC error correction (T) attribute is greater than 10, any portion of the extended preamble is used, or any attribute from Table 8-19, "upstream physical-layer burst attributes", with a type greater than 11 is present in the descriptor. Type 5 burst descriptors MUST NOT be used to describe IUC 5 or IUC 6. Type 5 burst descriptors MUST be used to describe IUCs 9-11.
+
+A burst descriptor MUST be included for each interval usage code that is to be used in the allocation MAP. The interval usage code MUST be one of the values from Table 8-20.
+
+Within each burst descriptor is an unordered list of physical-layer attributes, encoded as TLV values. These attributes are shown in Table 8-19. The CMTS MUST ensure that the set of burst attributes for all the burst descriptors in the UCD allow any CM on the upstream to be able to request enough mini-slots to be able to transmit a maximum size PDU (see clause 8.2.2, "packet-based MAC Frames").
+
+**Table 8-19 – Upstream physical-layer burst attributes**
+
+| Name                               | Type<br>(1 byte) | Length<br>(1 byte) | Value<br>(variable length)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
+|------------------------------------|------------------|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Modulation type                    | 1                | 1                  | 1 = QPSK<br>2 = 16QAM<br>3 = 8QAM<br>4 = 32QAM<br>5 = 64QAM<br>6 = 128QAM (S-CDMA only)<br>Values greater than 2 MUST NOT be used in a descriptor encoded in a type 4 TLV.                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
+| Differential encoding              | 2                | 1                  | 1 = on, 2 = off (see clause 6.2.13, "symbol mapping".)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+| Preamble length                    | 3                | 2                  | Up to 1536 bits for burst descriptors encoded in a type 5 TLV. Up to 1024 bits for descriptors encoded in a type 4 TLV. If this descriptor is encoded in a type 4 TLV then the substring of the preamble superstring defined by this parameter and the preamble value offset MUST NOT include any bits from the extended preamble pattern.<br>The value must be an integral number of symbols (see clause 6.2.9, "preamble prepend").                                                                                                                                                                                          |
+| Preamble value offset              | 4                | 2                  | Identifies the bits to be used in the preamble. This is specified as a starting offset into the preamble superstring (see Table 8-18). That is, a value of zero means that the first bit of the preamble for this burst type is the value of the first bit of the preamble superstring. A value of 100 means that the preamble is to use the 101st and succeeding bits from the preamble superstring. This value must be a multiple of the symbol size.<br>The first bit of the preamble is the first bit into the symbol mapper (see Figures 6-2 and 6-3), and is $I_1$ in the first symbol of the burst (see clause 6.2.13). |
+| FEC error correction (T)           | 5                | 1                  | 0-16 for descriptors encoded in a type 5 TLV.<br>0-10 for descriptors encoded in a type 4 TLV.<br>(0 implies no FEC. The number of codeword parity bytes is $2 \times T$ )                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
+| FEC codeword information bytes (k) | 6                | 1                  | Fixed: 16 to 253 (assuming FEC on)<br>Shortened: 16 to 253 (assuming FEC on)<br>(Not used if no FEC, $T = 0$ )                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
+| Scrambler seed                     | 7                | 2                  | The 15-bit seed value left justified in the 2-byte field. Bit 15 is the MSB of the first byte and the LSB of the second byte is not used (not used if scrambler is off).                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
+
+**Table 8-19 – Upstream physical-layer burst attributes**
+
+| Name                                 | Type (1 byte) | Length (1 byte) | Value (variable length)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
+|--------------------------------------|---------------|-----------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Maximum burst size                   | 8             | 1               | The maximum number of mini-slots that can be transmitted during this burst type. Absence of this configuration setting implies that the burst size is limited elsewhere. When the interval type is short data grant (IUC 5) or advanced PHY short data grant (IUC 9), this value MUST be present and greater than zero (see clause 9.1.2.5). If the CMTS needs to limit the maximum length of concatenated frames it SHOULD use this configuration setting to do so.                                                                         |
+| Guard time size                      | 9             | 1               | For TDMA channels, the number of modulation intervals measured from the end of the last symbol of one burst to the beginning of the first symbol of the preamble of an immediately following burst. In type 4 burst descriptors, the CMTS MUST choose the parameters such that the number of bytes that fit into any valid number of mini-slots will not change if the guard time is increased by 1. For S-CDMA channels, there is no guard time, and hence the CM MUST ignore this value. This TLV MUST NOT be present for S-CDMA channels. |
+| Last codeword length                 | 10            | 1               | 1 = fixed; 2 = shortened                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
+| Scrambler on/off                     | 11            | 1               | 1 = on; 2 = off                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
+| R-S interleaver depth ( $I_r$ )      | 12            | 1               | Reed-Solomon block interleaving depth. A depth of 0 indicates dynamic mode; a depth of 1 indicates R-S interleaving disabled (see clause 6.2.6) (0 through $\lfloor 2048/(K + 2T) \rfloor$ ). This TLV MUST be present for burst descriptors encoded in type 5 TLVs on DOCS 2.0 TDMA channels. This TLV MUST NOT be present for S-CDMA channels or in descriptors encoded in a type 4 TLV.                                                                                                                                                   |
+| R-S interleaver block size ( $B_r$ ) | 13            | 2               | Reed-Solomon block interleaving size in dynamic mode (18 through 2048). This TLV MUST be present in burst descriptors encoded in type 5 TLVs for DOCS 2.0 TDMA channels. This TLV MUST NOT be present on S-CDMA channels or in descriptors encoded in a type 4 TLV.                                                                                                                                                                                                                                                                          |
+| Preamble type                        | 14            | 1               | 1 = QPSK0<br>2 = QPSK1<br>(Refer to Figure 6-18 and to clause 6.2.9)<br>This TLV MUST NOT be present in descriptors encoded in a type 4 TLV.                                                                                                                                                                                                                                                                                                                                                                                                 |
+| S-CDMA spreader on/off               | 15            | 1               | 1 = on; 2 = off. This TLV MUST be present for S-CDMA channels. This TLV MUST NOT be present for non-S-CDMA channels or in descriptors encoded in a type 4 TLV.                                                                                                                                                                                                                                                                                                                                                                               |
+| S-CDMA codes per subframe            | 16            | 1               | Number of codes per sub-frame used in the S-CDMA framer (1 through 128). This TLV MUST be present for S-CDMA channels. This TLV MUST NOT be present for non-S-CDMA channels or in descriptors encoded in a type 4 TLV.                                                                                                                                                                                                                                                                                                                       |
+
+**Table 8-19 – Upstream physical-layer burst attributes**
+
+| Name                                 | Type (1 byte) | Length (1 byte) | Value (variable length)                                                                                                                                                                                        |
+|--------------------------------------|---------------|-----------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| S-CDMA framer interleaving step size | 17            | 1               | Size of interleaving steps used in S-CDMA framer (1 through 32). This TLV MUST be present for S-CDMA channels. This TLV MUST NOT be present for non-S-CDMA channels or in descriptors encoded in a type 4 TLV. |
+| TCM encoding                         | 18            | 1               | 1 = on; 2 = off. This TLV MUST be present for S-CDMA channels. This TLV MUST NOT be present for non-S-CDMA channels or in descriptors encoded in a type 4 TLV.                                                 |
+
+#### **8.3.3.1 Example of UCD encoded TLV data**
+
+An example of UCD encoded TLV data is given in Figure 8-18.
+
+Image: Diagram showing a sequence of TLV structures for UCD encoded data. Each row represents a TLV entry with Type, Length, and Value fields. The values are: Modulation rate, Frequency, Preamble pattern, Extended preamble pattern, First burst descriptor, Second burst descriptor, Third burst descriptor, and Fourth burst descriptor. The diagram uses visual offsets to show the sequential nature of the data.
+
+|        |              |                           |  |  |  |
+|--------|--------------|---------------------------|--|--|--|
+| Type 1 | Length 1     | Modulation rate           |  |  |  |
+| Type 2 | Length 4     | Frequency                 |  |  |  |
+| Type 3 | Length 1-128 | Preamble pattern          |  |  |  |
+| Type 6 | Length 1-64  | Extended preamble pattern |  |  |  |
+| Type 4 | Length N     | First burst descriptor    |  |  |  |
+| Type 4 | Length N     | Second burst descriptor   |  |  |  |
+| Type 5 | Length N     | Third burst descriptor    |  |  |  |
+| Type 5 | Length N     | Fourth burst descriptor   |  |  |  |
+
+J.122\_F8-18
+
+**Figure 8-18 – Example of UCD encoded TLV data**
+
+### 8.3.4 Upstream bandwidth allocation map (MAP)
+
+A CMTS MUST generate MAPs in the format shown in Figure 8-19.
+
+![Diagram of the MAP format showing a 32-bit word structure with fields for MAC management message header, Upstream channel ID, UCD count, Number of elements, Reserved, Alloc start time, Ack time, Ranging backoff start, Ranging backoff end, Data backoff start, Data backoff end, and MAP information elements.](dbf5c0f3c7836f717d9fe62c6c40b280_img.jpg)
+
+The diagram illustrates the structure of a 32-bit MAC management message. The word is divided into several fields. The first 32 bits (bits 0 to 31) form the 'MAC management message header'. This header is further subdivided: bits 0-7 are 'Upstream channel ID', bits 8-15 are 'UCD count', bits 16-23 are 'Number of elements', and bits 24-31 are 'Reserved'. Following the header are two 32-bit fields: 'Alloc start time' and 'Ack time'. Below these are four 8-bit fields: 'Ranging backoff start' (bits 0-7), 'Ranging backoff end' (bits 8-15), 'Data backoff start' (bits 16-23), and 'Data backoff end' (bits 24-31). The final part of the message is 'MAP information elements', which follows the header and the backoff fields. The diagram includes bit markers at 0, 8, 16, 24, and 31. A label 'J.122\_F8.19' is present at the bottom right.
+
+Diagram of the MAP format showing a 32-bit word structure with fields for MAC management message header, Upstream channel ID, UCD count, Number of elements, Reserved, Alloc start time, Ack time, Ranging backoff start, Ranging backoff end, Data backoff start, Data backoff end, and MAP information elements.
+
+Figure 8-19 – MAP format
+
+The parameters MUST be as follows:
+
+- **Upstream channel ID:** The identifier of the upstream channel to which this message refers.
+- **UCD count:** Matches the value of the configuration change count of the UCD which describes the burst parameters which apply to this map. See clause 11.3.2.
+- **Number of elements:** Number of information elements in the map.
+- **Reserved:** Reserved field for alignment.
+- **Alloc start time:** Effective start time from CMTS initialization (in mini-slots) for assignments within this map.
+- **Ack time:** Latest time, from CMTS initialization, (mini-slots) processed in upstream. This time is used by the CMs for collision detection purposes. See clause 9.4.
+- **Ranging backoff start:** Initial back-off window for initial ranging contention, expressed as a power of two. Values range 0-15 (the highest order bits must be unused and set to 0).
+- **Ranging backoff end:** Final back-off window for initial ranging contention, expressed as a power of two. Values range 0-15 (the highest order bits must be unused and set to 0).
+- **Data backoff start:** Initial back-off window for contention data and requests, expressed as a power of two. Values range 0-15 (the highest order bits must be unused and set to 0).
+- **Data backoff end:** Final back-off window for contention data and requests, expressed as a power of two. Values range 0-15 (the highest order bits must be unused and set to 0).
+- **MAP information elements:** MUST be in the format defined in Figure 8-20 and Table 8-20. Values for IUCs are defined in Table 8-20 and are described in detail in clause 9.1.2.
+
+NOTE – Refer to clause 9.1.1 for the relationship between alloc start/ack time and the timebase.
+
+![Figure 8-20 – MAP information element structure diagram showing the layout of intervals and fields (SID, IUC, Offset) across bit positions 0 to 31.](3ce6b213ec556257e32ff7451182369d_img.jpg)
+
+The diagram illustrates the structure of the MAP information element across multiple intervals. Each interval is a 32-bit word (bits 0 to 31) divided into three fields: SID (bits 0-13), IUC (bits 14-17), and Offset (bits 18-31). The intervals shown are:
+
+- First interval:** SID, IUC, Offset = 0
+- Second interval:** SID, IUC, Offset
+- ...** (indicated by wavy lines)
+- Last interval:** SID, IUC, Offset
+- End-of-list (null IE):** SID = 0, IUC = 7, Offset = map length
+- Acknowledgements and data grants pending:** SID, IUC, Offset = map length
+- ...** (indicated by wavy lines)
+
+Figure 8-20 – MAP information element structure diagram showing the layout of intervals and fields (SID, IUC, Offset) across bit positions 0 to 31.
+
+J.122\_F8-20
+
+**Figure 8-20 – MAP information element structure**
+
+**Table 8-20 – Allocation MAP information elements (IE)**
+
+| IE name <sup>a)</sup>                                                         | Interval usage code (IUC) (4 bits) | SID (14 bits)         | Mini-slot offset (14 bits)                                                                            |
+|-------------------------------------------------------------------------------|------------------------------------|-----------------------|-------------------------------------------------------------------------------------------------------|
+| Request                                                                       | 1                                  | Any                   | Starting offset of REQ region                                                                         |
+| REQ/data (refer to Annex A, "well-known addresses", for multicast definition) | 2                                  | Multicast             | Starting offset of IMMEDIATE data region (well-known multicasts define start intervals)               |
+| Initial maintenance <sup>b)</sup>                                             | 3                                  | Broadcast or unicast  | Starting offset of MAINT region (used in initial or periodic ranging)                                 |
+| Station maintenance                                                           | 4                                  | Unicast <sup>c)</sup> | Starting offset of MAINT region (used in periodic ranging)                                            |
+| Short data grant <sup>d)</sup>                                                | 5                                  | Unicast               | Starting offset of data grant assignment; If inferred length = 0, then it is a data grant pending     |
+| Long data grant                                                               | 6                                  | Unicast               | Starting offset of data grant assignment; If inferred length = 0, then it is a data grant pending     |
+| Null IE                                                                       | 7                                  | Zero                  | Ending offset of the previous grant. Used to bound the length of the last actual interval allocation. |
+| Data ack                                                                      | 8                                  | Unicast               | CMTS sets to map length                                                                               |
+| Advanced PHY short <sup>e)</sup> data grant                                   | 9                                  | Unicast               | Starting offset of data grant assignment; If inferred length = 0, then it is a data grant pending     |
+
+**Table 8-20 – Allocation MAP information elements (IE)**
+
+| IE name <sup>a)</sup>          | Interval usage code (IUC) (4 bits) | SID (14 bits) | Mini-slot offset (14 bits)                                                                        |
+|--------------------------------|------------------------------------|---------------|---------------------------------------------------------------------------------------------------|
+| Advanced PHY long data grant   | 10                                 | Unicast       | Starting offset of data grant assignment; If inferred length = 0, then it is a data grant pending |
+| Advanced PHY unsolicited grant | 11                                 | Unicast       | Starting offset of data grant assignment                                                          |
+| Reserved                       | 12-14                              | Any           | Reserved                                                                                          |
+| Expansion                      | 15                                 | Expanded IUC  | # of additional 32-bit words in this IE                                                           |
+
+a) Each IE is a 32-bit quantity, of which the most significant 14 bits represent the SID, the middle 4 bits the IUC, and the low-order 14 bits the mini-slot offset.  
+b) The CMTS MUST NOT use a unicast SID with an initial maintenance IUC on any upstream that is not a DOCS 2.0-only upstream.  
+c) The SID used in the station maintenance IE MUST be a temporary SID, or the primary SID that was assigned in the REG-RSP message to a CM.  
+d) The distinction between long and short data grants is related to the amount of data that can be transmitted in the grant. A short data grant interval may use FEC parameters that are appropriate to short packets while a long data grant may be able to take advantage of greater FEC coding efficiency.  
+e) The advanced PHY types are provided for channels carrying a combination of DOCS 1.x and DOCS 2.0 bursts and also for channels carrying DOCS 2.0 bursts only.
+
+### **8.3.5 Ranging request (RNG-REQ)**
+
+A ranging request MUST be transmitted by a CM at initialization on an upstream other than a DOCS 2.0-only upstream, and periodically on request from CMTS to determine network delay and request power adjustment. On a DOCS 2.0-only upstream, the CM transmits a INIT-RNG-REQ (see clause 8.3.26) message at initialization instead, but uses the RNG-REQ for all unicast maintenance opportunities provided by the CMTS. This message MUST use an FC\_TYPE = MAC-specific header and FC\_PARM = timing MAC header. This MUST be followed by a packet PDU in the format shown in Figure 8-21.
+
+![Diagram of a 32-bit packet PDU structure. The top part is a 32-bit MAC management message header. The bottom part is divided into three fields: SID (bits 0-15), Downstream channel ID (bits 16-23), and Pending till complete (bits 24-31).](024914144d624b7f5dc22aaa5c3967b9_img.jpg)
+
+Bit 0 8 16 24 31
+
+|                               |  |                       |                       |
+|-------------------------------|--|-----------------------|-----------------------|
+| MAC management message header |  |                       |                       |
+| SID                           |  | Downstream channel ID | Pending till complete |
+
+J.122\_F8-21
+
+Diagram of a 32-bit packet PDU structure. The top part is a 32-bit MAC management message header. The bottom part is divided into three fields: SID (bits 0-15), Downstream channel ID (bits 16-23), and Pending till complete (bits 24-31).
+
+**Figure 8-21 – Packet PDU following the timing header**
+
+Parameters MUST be as follows:
+
+- **SID:** For RNG-REQ messages transmitted in broadcast initial maintenance intervals:
+  - Initialization SID if modem is attempting to join the network.
+
+- Initialization SID if modem has not yet registered and is changing upstream, downstream, or both downstream and upstream channels as directed by a downloaded parameter file.
+- Primary SID (previously assigned in REG-RSP) if modem is registered and is changing upstream channels, or if the CM is redoing initial ranging as a result of a DCC, UCC or UCD change (see clauses 8.3.3 and 11.3.2).
+
+For RNG-REQ messages transmitted in unicast initial maintenance or station maintenance intervals:
+
+- Temporary SID if modem has not yet registered.
+- Primary SID (previously assigned in REG-RSP) if modem is registered or is redoing initial ranging as a result of DCC, UCC or UCD change.
+
+This is a 16-bit field of which the lower 14 bits define the SID, with bits 14 and 15 defined to be 0.
+
+- **Downstream channel ID:** The identifier of the downstream channel on which the CM received the UCD which described this upstream. This is an 8-bit field.
+- **Pending till complete:** If zero, then all previous ranging response attributes have been applied prior to transmitting this request. If non-zero, then this is time estimated to be needed to complete assimilation of ranging parameters. Note that only equalization can be deferred. Units are in unsigned centiseconds (10 ms).
+
+A CM MUST set the RSVD field of the MAC management message header to report support of the S-CDMA maximum scheduled codes if and only if the CMTS indicated that it supports the S-CDMA maximum scheduled codes from TLV-17 of the UCD for the upstream channel on which the CM is ranging. In this case, the CM MUST report the maximum ratio of number of active codes to maximum scheduled codes that the CM can support; this ratio is indicated by a bit mask in the reserved field as shown below. For example, if the number of active codes on the channel is 128 and the CM supports a minimum of 64 scheduled codes (the minimum number of allowed active codes), the CM would report a ratio of 2. The CMTS will use this value in calculating an appropriate value for maximum scheduled codes to assign to the CM. The CM SHOULD support a maximum ratio of 32.
+
+When the CM reports support for the S-CDMA maximum scheduled codes, the CM MUST also report its current transmit power shortfall (in dB). The CM power shortfall is the difference between the current target transmit power of the ranging request and the maximum S-CDMA spreader-on transmit power of 53 dBmV. The CM MUST report a power shortfall of 0 if the current target transmit power of the ranging request is less than or equal to 53 dBmV. This value will be used by the CMTS for calculating appropriate values for S-CDMA maximum scheduled codes and S-CDMA power headroom for the CM.
+
+The format of the RSVD field is:
+
+|                                                    |                                                                                          |                                         |
+|----------------------------------------------------|------------------------------------------------------------------------------------------|-----------------------------------------|
+| Bit 7: 1= S-CDMA maximum scheduled codes supported | Bits 6 to 5: CM maximum ratio of:<br><Anchor1><br>00 = 20<br>1 = 8<br>10 = 16<br>11 = 32 | Bit 4 to 0: CM power shortfall (1/4 dB) |
+|----------------------------------------------------|------------------------------------------------------------------------------------------|-----------------------------------------|
+
+### 8.3.6 Ranging response (RNG-RSP)
+
+A ranging response MUST be transmitted by a CMTS in response to received RNG-REQ or INIT-RNG-REQ. The state machines describing the ranging procedure appear in clause 11.2.4. In that procedure it may be noted that, from the point of view of the CM, reception of a ranging response is stateless. In particular, the CM MUST be prepared to receive a ranging response at any time, not just following a ranging request.
+
+To provide for flexibility, the message parameters following the upstream channel ID MUST be encoded in a type/length/value (TLV) form.
+
+![Diagram of Ranging response message structure](b02ba0b73e95416eb547976f6145b169_img.jpg)
+
+The diagram illustrates the structure of a Ranging response message. It is a 32-bit word, with bits numbered 0 to 31. The first 16 bits (bits 0-15) are the MAC management message header, indicated by a break symbol. The next 8 bits (bits 16-23) are the SID from request. The following 8 bits (bits 24-31) are the Upstream channel ID. The final 16 bits (bits 32-47) are TLV encoded information. The diagram is labeled J.122\_F8-22.
+
+| Bit   | 0                             | 8 | 16               | 24 | 31                  |  |
+|-------|-------------------------------|---|------------------|----|---------------------|--|
+| Field | MAC management message header |   | SID from request |    | Upstream channel ID |  |
+| Field | TLV encoded information       |   |                  |    |                     |  |
+
+Diagram of Ranging response message structure
+
+Figure 8-22 – Ranging response
+
+A CMTS MUST generate ranging responses in the form shown in Figure 8-22, including all of the following parameters:
+
+- **SID:** If the modem is being instructed by this response to move to a different channel, this is initialization SID. Otherwise, this is the SID from the corresponding RNG-REQ to which this response refers, except that if the corresponding RNG-REQ was an initial ranging request specifying an initialization SID, then this is the assigned temporary SID.
+- **Upstream channel ID:** The identifier of the upstream channel on which the CMTS received the RNG-REQ or INIT-RNG-REQ to which this response refers. On the first ranging response received by the CM during initial ranging, this channel ID may be different from the channel ID the CM used to transmit the range request (see Appendix III). Thus, the CM MUST use this channel ID for the rest of its transactions, not the channel ID from which it initiated the range request.
+
+All other parameters are coded as TLV tuples:
+
+- **Ranging status:** Used to indicate whether upstream messages are received within acceptable limits by CMTS.
+- **Timing adjust information:** The amount by which to change the ranging offset of the burst transmission so that bursts arrive at the expected mini-slot time at the CMTS. The units are  $(1/10.24 \text{ MHz}) = 97.65625 \text{ ns}$ . A negative value implies the ranging offset is to be decreased, resulting in later times of transmission at the CM (see Table 6-8 and clause 6.2.19.1, "ranging offset").
+- **Power adjust information:** Specifies the relative change in transmission power level that the CM is to make in order that transmissions arrive at the CMTS at the desired power.
+
+- **Frequency adjust information:** Specifies the relative change in transmission frequency that the CM is to make in order to better match the CMTS (this is fine-frequency adjustment within a channel, not re-assignment to a different channel).
+- **CM transmitter equalization information:** This provides the equalization coefficients for the pre-equalizer.
+- **Downstream frequency override:** An optional parameter. The downstream frequency with which the modem should redo initial ranging (see clause 8.3.6.3).
+- **Upstream channel ID override:** An optional parameter. The identifier of the upstream channel with which the modem should redo initial ranging (see clause 8.3.6.3).
+- **Fine timing adjust extension:** Higher resolution timing adjust offset to be appended to timing adjust, integer part. The units are  $(1/(256 \times 10.24 \text{ MHz})) = 0.3814697265625 \text{ ns}$ . This parameter provides finer granularity timing offset information for transmission in S-CDMA mode. This TLV MUST be present for S-CDMA channels (see clause 6.2.20).
+- **S-CDMA maximum scheduled codes:** The value that the CMTS uses to limit the number of codes scheduled to a CM in an S-CDMA frame. CMs that implement the S-CDMA maximum scheduled codes use this value to limit the maximum size of a concatenated burst in an S-CDMA frame.
+- **S-CDMA power headroom:** CMs that implement the S-CDMA maximum scheduled codes MUST use this value to control transmit power as per clause 6.2.18.2.
+
+#### 8.3.6.1 Encodings
+
+The type values used MUST be those defined in Table 8-21 and Figure 8-23. These are unique within the ranging response message but not across the entire MAC message set. The type and length fields MUST each be 1 octet in length.
+
+**Table 8-21 – Ranging response message encodings**
+
+| Name                           | Type (1 byte) | Length (1 byte) | Value (variable length)                                                                                                                                                                               |
+|--------------------------------|---------------|-----------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Timing adjust, integer part    | 1             | 4               | TX timing offset adjustment (signed 32-bit, units of $(6.25 \text{ } \mu\text{s}/64)$ )                                                                                                               |
+| Power level adjust             | 2             | 1               | TX power offset adjustment (signed 8-bit, 1/4-dB units)                                                                                                                                               |
+| Offset frequency adjust        | 3             | 2               | TX frequency offset adjustment (signed 16-bit, Hz units)                                                                                                                                              |
+| Transmit equalization adjust   | 4             | n               | TX equalization data to be convolved with current values (refer to clause 6.2.15). See below for details about representation. This TLV MUST NOT be included in a RNG-RSP that includes a type 9 TLV. |
+| Ranging status                 | 5             | 1               | 1 = continue, 2 = abort, 3 = success                                                                                                                                                                  |
+| Downstream frequency override  | 6             | 4               | Centre frequency of new downstream channel in Hz                                                                                                                                                      |
+| Upstream channel ID override   | 7             | 1               | Identifier of the new upstream channel                                                                                                                                                                |
+| Timing adjust, fractional part | 8             | 1               | TX timing fine offset adjustment. Eight-bit unsigned value specifying the fine timing adjustment in units of $1/(245 \times 10.24 \text{ MHz})$                                                       |
+
+**Table 8-21 – Ranging response message encodings**
+
+| Name                           | Type<br>(1 byte) | Length<br>(1 byte) | Value<br>(variable length)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+|--------------------------------|------------------|--------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Transmit equalization set      | 9                | n                  | TX equalization data to be loaded in place of current values (refer to clause 6.2.10). See below for details about representation. This TLV MUST NOT be included in a RNG-RSP to a DOCS 1.x CM, and MUST not be included in a RNG-RSP that includes a type 4 TLV.                                                                                                                                                                                                                                                                  |
+| S-CDMA maximum scheduled codes | 10               | 1                  | A CMTS MAY send this TLV only if a CM indicated in the RNG-REQ or INIT-RNG-REQ that it supports the S-CDMA maximum scheduled codes.<br>A value of 0 means no code limit. Other possible values range from 4 to number_active_codes inclusive. Maximum scheduled codes must be an integer multiple of codes_per_mini-slots.<br>If S-CDMA mode is disabled, this TLV MUST NOT be present. Absence of this TLV indicates that maximum scheduled codes is inactive for this CM, which MUST then use the S-CDMA number of active codes. |
+| S-CDMA power headroom          | 11               | 1                  | A CMTS MUST send this TLV to a CM in conjunction with TLV-10.<br>If S-CDMA mode is disabled, this TLV MUST NOT be present.<br>The units are dB. The range of this TLV is from 0 to $4 \cdot 10 \log(\langle \text{Anchor2} \rangle)$<br>NOTE – A value of 0 for TLV-10 restricts the range to 0 for TLV-11.                                                                                                                                                                                                                        |
+| Reserved                       | 12-255           | n                  | Reserved for future use                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
+
+| Type<br>4                      | Length   | Main tap location              | Number of forward taps per symbol |
+|--------------------------------|----------|--------------------------------|-----------------------------------|
+| Number of forward taps (N)     | Reserved |                                |                                   |
+| First coefficient $F_1$ (real) |          | First coefficient $F_1$ (imag) |                                   |
+|                                |          |                                |                                   |
+| Last coefficient $F_N$ (real)  |          | Last coefficient $F_N$ (imag)  |                                   |
+
+J.122\_F8-23
+
+**Figure 8-23 – Generalized decision feedback equalization coefficients**
+
+The number of taps per modulation interval T MUST be either 1, 2 or 4. The main tap location refers to the position of the zero delay tap, between 1 and N. For a T-spaced equalizer, the number
+
+of taps per modulation interval field MUST be set to "1". The total number of taps MAY range up to 64. Each tap consists of a real and imaginary coefficient entry in the table.
+
+If more than 255 bytes are needed to represent equalization information, then several type 4 or 9 elements MAY be used. Data MUST be treated as if byte-concatenated, that is, the first byte after the length field of the second type 4 or 9 element is treated as if it immediately followed the last byte of the first type 4 or 9 element.
+
+Figure 6-28 depicts the operation of the equalizer.
+
+#### 8.3.6.2 Example of TLV data
+
+An example of TLV data is given in Figure 8-24.
+
+|        |          |                                                    |  |
+|--------|----------|----------------------------------------------------|--|
+| Type 1 | Length 4 | Timing adjust                                      |  |
+| Type 2 | Length 1 | Power adjust                                       |  |
+| Type 3 | Length 2 | Frequency adjust information                       |  |
+| Type 4 | Length x | x bytes of CM transmitter equalization information |  |
+| Type 5 | Length 1 | Ranging status                                     |  |
+
+J.122\_F8-24
+
+**Figure 8-24 – Example of TLV data**
+
+#### 8.3.6.3 Overriding channels prior to registration
+
+The RNG-RSP message allows the CMTS to instruct the modem to move to a new downstream and/or upstream channel and to repeat initial ranging. However, the CMTS may do this only in response to an initial ranging request from a modem that is attempting to join the network, or in response to any of the unicast ranging requests that take place immediately after this initial ranging and up to the point where the modem successfully completes periodic ranging. If a downstream frequency override is specified in the RNG-RSP, the modem MUST re-initialize its MAC (see clause 11.2) using initial ranging with the specified downstream centre frequency as the first scanned channel. For the upstream channel, the modem selects its channel based on received UCD messages as per clause 11.2.2.
+
+If an upstream channel ID override is specified in the RNG-RSP, the modem MUST re-initialize its MAC (see clause 11.2) using initial ranging with the upstream channel specified in the RNG-RSP for its first attempt and the same downstream frequency on which the RNG-RSP was received.
+
+If both downstream frequency and upstream channel ID overrides are present in the RNG-RSP, the modem MUST re-initialize its MAC (refer to clause 11.2) using initial ranging with the specified downstream frequency and upstream channel ID for its first attempt.
+
+Note that when a modem with an assigned temporary SID is instructed to move to a new downstream and/or upstream channel and to redo initial ranging, the modem MUST consider the temporary SID to be de-assigned. The modem MUST redo initial ranging using the initialization SID.
+
+Configuration file settings for upstream channel ID and downstream frequency are optional, but if specified in the configuration file they take precedence over the ranging response parameters. Once ranging is complete, only clause C.1.1.2, UCC-REQ and DCC-REQ mechanisms are available for
+
+moving the modem to a new upstream channel, and only clauses C.1.1.1, C.1.1.21 and DCC-REQ mechanisms are available for moving the modem to a new downstream channel.
+
+### 8.3.7 Registration request (REG-REQ)
+
+A registration request MUST be transmitted by a CM at initialization after receipt of a CM parameter file, except as outlined in clauses 11.2.8 and 11.2.9.
+
+To provide for flexibility, the message parameters following the SID MUST be encoded in a type/length/value form.
+
+![Diagram of a Registration request message structure. The message is 32 bits (0 to 31) long. It consists of a MAC management message header (bits 0-31), a SID field (bits 0-15), and TLV encoded information (bits 16-31).](da87c1b628b63a046d8a0d0fc2c058ea_img.jpg)
+
+The diagram illustrates the structure of a Registration request message. It is a 32-bit word, with bits numbered 0 to 31. The message is divided into three main parts:
+
+- MAC management message header:** This part occupies the entire 32-bit word (bits 0 to 31). It is indicated by a bracket spanning the top of the diagram, with break symbols (wavy lines) at the ends.
+- SID:** This field occupies the first 16 bits (bits 0 to 15). It is shown as a rectangle in the second row of the diagram.
+- TLV encoded information:** This part occupies the remaining 16 bits (bits 16 to 31). It is shown as a rectangle in the third row of the diagram.
+
+The label "J.122\_F8-25" is located at the bottom right of the diagram.
+
+Diagram of a Registration request message structure. The message is 32 bits (0 to 31) long. It consists of a MAC management message header (bits 0-31), a SID field (bits 0-15), and TLV encoded information (bits 16-31).
+
+Figure 8-25 – Registration request
+
+A CM MUST generate registration requests in the form shown in Figure 8-25, including the following parameters:
+
+- **SID:** Temporary SID for this CM.
+
+All other parameters are coded as TLV tuples as defined in Annex C.
+
+Registration requests can contain many different TLV parameters, some of which are set by the CM according to its configuration file and some of which are generated by the CM itself. If found in the configuration file, the following configuration settings MUST be included in the registration request.
+
+Configuration file settings:
+
+- All configuration settings included in the CMTS MIC calculation as specified in clause D.3.1.
+- Enable 2.0 mode.
+- Downstream channel list.
+- CMTS MIC configuration setting.
+
+NOTE – The CM MUST forward DOCSIS extension field configuration settings to the CMTS in the same order in which they were received in the configuration file to allow the message integrity check to be performed.
+
+The following registration parameter MUST be included in the registration request.
+
+- Vendor-specific parameter: Vendor ID configuration setting (vendor ID of CM).
+
+The modem capabilities encodings registration parameter MUST also be included in the registration request<sup>13</sup>.
+
+The following registration parameters MAY also be included in the registration request:
+
+- Modem IP address.
+- Vendor-specific capabilities.
+
+The vendor-specific capabilities field is for vendor-specific information not included in the configuration file.
+
+The following configuration settings MUST NOT be forwarded to the CMTS in the registration request:
+
+- Software upgrade filename.
+- Software upgrade TFTP server IP address.
+- SNMP write-access control.
+- SNMP MIB object.
+- SNMPv3 kickstart value.
+- CPE Ethernet MAC address.
+- HMAC digest.
+- End configuration setting.
+- Pad configuration setting.
+- Telephone settings option.
+- SNMPv3 notification receiver.
+
+### **8.3.8 Registration response (REG-RSP)**
+
+A registration response MUST be transmitted by the CMTS in response to a received REG-REQ.
+
+To provide for flexibility, the message parameters following the response field MUST be encoded in a TLV format.
+
+---
+
+<sup>13</sup> The CM MUST specify all of its modem capabilities in its registration request subject to the restrictions in clause C.1.3.1. The CMTS MUST NOT assume any modem capability which is defined but not explicitly indicated in the CM's registration request.
+
+![Diagram of Registration response format showing a 32-bit message structure. The top section is the MAC management message header (bits 0-31). Below it, the first 16 bits are split into 'SID from corresponding RNG-REQ' (bits 0-8) and 'Response' (bits 9-16). The remaining 16 bits (bits 17-31) are 'TLV encoded information'. A break symbol is shown in the header section. The diagram is labeled J.122_F8-26 at the bottom right.](28e47e64ac18ca4d8924dab65cedc2d8_img.jpg)
+
+Diagram of Registration response format showing a 32-bit message structure. The top section is the MAC management message header (bits 0-31). Below it, the first 16 bits are split into 'SID from corresponding RNG-REQ' (bits 0-8) and 'Response' (bits 9-16). The remaining 16 bits (bits 17-31) are 'TLV encoded information'. A break symbol is shown in the header section. The diagram is labeled J.122\_F8-26 at the bottom right.
+
+**Figure 8-26 – Registration response format**
+
+A CMTS MUST generate registration responses in the form shown in Figure 8-26, including both of the following parameters:
+
+- **SID from corresponding REG-REQ:** SID from corresponding REG-REQ to which this response refers (this acts as a transaction identifier).
+- **Response:** For REG-RSP to a modem registering as a 1.0 modem (i.e., REG-REQ contains DOCS 1.0 class of service encodings).
+  - 0 = Okay
+  - 1 = Authentication failure
+  - 2 = Class of service failure
+
+For REG-RSP to a modem registering as a 1.1 or 2.0 modem (i.e., REG-REQ contains service flow encodings), this field MUST contain one of the confirmation codes in clauses C.4 and C.4.2.
+
+NOTE 1 – Failures apply to the entire registration request. Even if only a single requested service flow or DOCS 1.0 service class is invalid or undeliverable, the entire registration is failed.
+
+If the REG-REQ was successful, and contained service flow parameters, classifier parameters or payload header suppression parameters, the REG-RSP MUST contain, for each of these:
+
+- **Classifier parameters:** All of the classifier parameters from the corresponding REG-REQ, plus the classifier identifier assigned by the CMTS.
+- **Service flow parameters:** All the service flow parameters from the REG-REQ, plus the service flow ID assigned by the CMTS. Every service flow that contained a service class name that was admitted/activated<sup>14</sup> MUST be expanded into the full set of TLVs defining the service flow. Every upstream service flow that was admitted/activated MUST have a service identifier assigned by the CMTS. A service flow that was only provisioned will include only those QoS parameters that appeared in the REG-REQ, plus the assigned service flow ID.
+- **Payload header suppression parameters:** All the payload header suppression parameters from the REG-REQ, plus the payload header suppression index assigned by the CMTS.
+
+<sup>14</sup> The ActiveQoSParamSet or AdmittedQoSParamSet is non-null.
+
+If the REG-REQ failed due to service flow parameters, classifier parameters or payload header suppression parameters, and the response is not one of the major error codes in clause C.4.2, the REG-RSP MUST contain at least one of the following:
+
+- **Classifier error set:** A classifier error set and identifying classifier reference and service flow reference MUST be included for at least one failed classifier in the corresponding REG-REQ. Every classifier error set MUST include at least one specific failed classifier parameter of the corresponding classifier.
+- **Service flow error set:** A service flow error set and identifying service flow reference MUST be included for at least one failed service flow in the corresponding REG-REQ. Every service flow error set MUST include at least one specific failed QoS parameter of the corresponding service flow.
+- **Payload header suppression error set:** A PHS error set and identifying service flow reference and classifier reference pair MUST be included for at least one failed PHS rule in the corresponding REG-REQ. Every PHS error set MUST include at least one specific failed PHS parameter of the corresponding failed PHS rule.
+
+Service class name expansion always occurs at admission time. Thus, if a registration request contains a service flow reference and a service class name for deferred admission/activation, the registration response MUST NOT include any additional QoS parameters except the service flow identifier (refer to clause 10.1.3).
+
+If the corresponding registration request contains DOCS 1.0 service class TLVs (refer to clause C.1.1.4), the registration response MUST contain the following TLV tuples:
+
+- **DOCS 1.0 service class data:** Returned when response = okay. This is a service ID/service class tuple for each class of service granted.
+
+NOTE 2 – Service class IDs MUST be those requested in the corresponding REG-REQ.
+
+- **Service not available:** Returned when response = class of service failure. If a service class cannot be supported, this configuration setting is returned in place of the service class data.
+
+All other parameters are coded TLV tuples.
+
+- **Modem capabilities:** The CMTS response to the capabilities of the modem (if present in the registration request).
+- **Vendor-specific data:** As defined in Annex C:
+  - vendor ID configuration setting (vendor ID of the CMTS);
+  - vendor-specific extensions.
+
+#### 8.3.8.1 Encodings
+
+The type values used MUST be those shown below. These are unique within the registration response message but not across the entire MAC message set. The type and length fields MUST each be one octet.
+
+##### 8.3.8.1.1 Modem capabilities
+
+This field defines the CMTS response to the modem capabilities field in the registration request. The CMTS MUST respond to the modem capability to indicate whether they may be used. If the CMTS does not recognize a modem capability, it MUST return the TLV with the value zero ("off") in the registration response.
+
+Only capabilities set to "on" in the REG-REQ may be set "on" in the REG-RSP as this is the handshake indicating that they have been successfully negotiated. Capabilities set to "off" in the REG-REQ MUST also be set to "off" in the REG-RSP.
+
+Encodings are as defined for the registration request.
+
+##### 8.3.8.1.2 DOCS 1.0 service class data
+
+A DOCS 1.0 service-class-data parameter MUST be present in the registration response for each DOCS 1.0 class-of-service parameter (refer to clause C.1.1.4) in the registration request.
+
+This encoding defines the parameters associated with a requested class of service. It is somewhat complex in that it is composed from a number of encapsulated type/length/value fields. The encapsulated fields define the particular class-of-service parameters for the class of service in question. Note that the type fields defined are only valid within the encapsulated service class data configuration setting string. A single service class data configuration setting MUST be used to define the parameters for a single service class. Multiple class definitions MUST use multiple service class data configuration setting sets.
+
+Each received DOCS 1.0 class-of-service parameter must have a unique class ID in the range 1 to 16. If no class ID is present for any single DOCS 1.0 class-of-service TLV in the REG-REQ, the CMTS MUST send a REG-RSP with a class-of-service failure response and no DOCS 1.0 class-of-service TLVs.
+
+| Type | Length | Value                      |
+|------|--------|----------------------------|
+| 1    | n      | Encoded service class data |
+
+###### Class ID:
+
+The value of the field MUST specify the identifier for the class of service to which the encapsulated string applies. This MUST be a class which was requested in the associated REG-REQ, if present.
+
+| Type | Length | Value        |
+|------|--------|--------------|
+| 1.1  | 1      | From REG-REQ |
+
+**Valid range:** The class ID MUST be in the range 1 to 16.
+
+**Service ID:** The value of the field MUST specify the SID associated with this service class.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 1.2  | 2      | SID   |
+
+### 8.3.9 Registration acknowledge (REG-ACK)
+
+A registration acknowledge MUST be transmitted by the CM in response to a REG-RSP from the CMTS with a confirmation code of okay (0)<sup>15</sup>. It confirms acceptance by the CM of the QoS parameters of the flow as reported by the CMTS in its REG-RSP. The format of a REG-ACK MUST be as shown in Figure 8-27.
+
+---
+
+<sup>15</sup> The registration acknowledge is a DOCS 1.1/2.0 message. Refer to Annex G for details of registration interoperability issues.
+
+![Diagram of a Registration acknowledgment message structure. The message is 32 bits (0-31) long. The first part is the 'MAC management message header' (bits 0-31). The second part contains 'SID from corresponding REG-RSP' (bits 0-15) and 'Confirmation code' (bits 16-23). The third part is 'TLV encoded information' (bits 24-31).](f512ae9c630f2fb53197fa77a1bda0e8_img.jpg)
+
+Diagram illustrating the structure of a Registration acknowledgment message. The message is 32 bits (0-31) long. The first part is the MAC management message header (bits 0-31). The second part contains the SID from corresponding REG-RSP (bits 0-15) and Confirmation code (bits 16-23). The third part is TLV encoded information (bits 24-31).
+
+|                                |   |   |                   |    |    |
+|--------------------------------|---|---|-------------------|----|----|
+| Bit                            | 0 | 8 | 16                | 24 | 31 |
+| MAC management message header  |   |   |                   |    |    |
+| SID from corresponding REG-RSP |   |   | Confirmation code |    |    |
+| TLV encoded information        |   |   |                   |    |    |
+
+J.122\_F8-27
+
+Diagram of a Registration acknowledgment message structure. The message is 32 bits (0-31) long. The first part is the 'MAC management message header' (bits 0-31). The second part contains 'SID from corresponding REG-RSP' (bits 0-15) and 'Confirmation code' (bits 16-23). The third part is 'TLV encoded information' (bits 24-31).
+
+**Figure 8-27 – Registration acknowledgment**
+
+The parameters MUST be as follows:
+
+- **SID from corresponding REG-RSP:** SID from corresponding REG-RSP to which this acknowledgment refers (this acts as a transaction identifier).
+- **Confirmation code:** The appropriate confirmation code (refer to clause C.4) for the entire corresponding registration response.
+
+The CM is required to send all provisioned classifiers, service flows and payload header suppression rules to the CMTS in the REG-REQ (see clause 8.3.7). The CMTS will return them with identifiers, expanding service class names if present, in the REG-RSP (see clause 8.3.8). Since the CM may be unable to support one or more of these provisioned items, the REG-ACK includes error sets for all failures related to these provisioned items.
+
+If there were any failures of provisioned items, the REG-ACK MUST include the error sets corresponding to those failures. The error set identification is provided by using service flow ID and classifier ID from corresponding REG-RSP. If a classifier ID or SFID was omitted in the REG-RSP, the CM MUST use the appropriate reference (classifier reference, SF reference) in the REG-ACK.
+
+- **Classifier error set:** A classifier error set and identifying classifier reference/identifier and service flow reference/identifier pair MUST be included for at least one failed classifier in the corresponding REG-RSP. Every classifier error set MUST include at least one specific failed classifier parameter of the corresponding classifier. This parameter MUST be omitted if the entire REG-REQ/RSP is successful.
+- **Service flow error set:** A service flow error set of the REG-ACK message encodes specifics of failed service flows in the REG-RSP message. A service flow error set and identifying service flow reference/identifier MUST be included for at least one failed QoS parameter of at least one failed service flow in the corresponding REG-RSP message. This parameter MUST be omitted if the entire REG-REQ/RSP is successful.
+- **Payload header suppression error set:** A PHS error set and identifying service flow reference/identifier and classifier reference/identifier pair MUST be included for at least one failed PHS rule in the corresponding REG-RSP. Every PHS error set MUST include at least one specific failed PHS of the failed PHS rule. This parameter MUST be omitted if the entire REG-REQ/RSP is successful.
+
+Per service flow acknowledgment is necessary not just for synchronization between the CM and CMTS, but also to support use of the service class name (refer to clause 10.1.3). Since the CM may not know all of the service flow parameters associated with a service class name when making the registration request, it may be necessary for the CM to NAK a registration response if it has insufficient resources to support this service flow.
+
+### 8.3.10 Upstream channel change request (UCC-REQ)
+
+An upstream channel change request MAY be transmitted by a CMTS to cause a CM to change the upstream channel on which it is transmitting. The format of an UCC-REQ message is shown in Figure 8-28.
+
+![Diagram of UCC-REQ message format showing a 32-bit structure with a MAC management message header and an 8-bit Upstream channel ID field.](893d65bf826925a7283359b1672010a0_img.jpg)
+
+The diagram illustrates the structure of an UCC-REQ message. It is a 32-bit word, with bit positions 0, 8, 16, 24, and 31 marked at the top. The first 16 bits (bits 0-15) are the MAC management message header, indicated by a bracket and a break symbol. The next 8 bits (bits 16-23) are the Upstream channel ID. The remaining 8 bits (bits 24-31) are TLV encoded information. The label J.122\_F8-28 is at the bottom right.
+
+Diagram of UCC-REQ message format showing a 32-bit structure with a MAC management message header and an 8-bit Upstream channel ID field.
+
+Figure 8-28 – Upstream channel change request
+
+Parameters MUST be as follows:
+
+- **Upstream channel ID:** The identifier of the upstream channel to which the CM is to switch for upstream transmissions. This is an 8-bit field.
+
+Upon receipt of a UCC-REQ message, the CM MUST perform ranging with broadcast initial maintenance.
+
+### 8.3.11 Upstream channel change response (UCC-RSP)
+
+An upstream channel change response MUST be transmitted by a CM in response to a received upstream channel change request message to indicate that it has received and is complying with the UCC-REQ. The format of an UCC-RSP message is shown in Figure 8-29.
+
+![Diagram of UCC-RSP message format showing a 32-bit structure with a MAC management message header and an 8-bit Upstream channel ID field.](612f485c508ab6745d6dfe894f15e8cc_img.jpg)
+
+The diagram illustrates the structure of an UCC-RSP message. It is a 32-bit word, with bit positions 0, 8, 16, 24, and 31 marked at the top. The first 16 bits (bits 0-15) are the MAC management message header, indicated by a bracket and a break symbol. The next 8 bits (bits 16-23) are the Upstream channel ID. The remaining 8 bits (bits 24-31) are TLV encoded information. The label J.122\_F8-29 is at the bottom right.
+
+Diagram of UCC-RSP message format showing a 32-bit structure with a MAC management message header and an 8-bit Upstream channel ID field.
+
+Figure 8-29 – Upstream channel change response
+
+Before it begins to switch to a new upstream channel, a CM MUST transmit a UCC-RSP on its existing upstream channel. A CM MAY ignore an UCC-REQ message while it is in the process of
+
+performing a channel change. When a CM receives a UCC-REQ message requesting that it switch to an upstream channel that it is already using, the CM MUST respond with a UCC-RSP message on that channel indicating that it is already using the correct channel.
+
+After switching to a new upstream channel, a CM MUST re-range using broadcast initial ranging, and then MUST proceed without re-performing registration. The full procedure for changing channels is described in clause 11.3.3.
+
+Parameters MUST be as follows:
+
+- **Upstream channel ID:** The identifier of the upstream channel to which the CM is to switch for upstream transmissions. This MUST be the same channel ID specified in the UCC-REQ message. This MUST be an 8-bit field.
+
+### 8.3.12 Dynamic service addition request (DSA-REQ)
+
+A dynamic service addition request MAY be sent by a CM or CMTS to create a new service flow.
+
+![Diagram of a Dynamic service addition request (DSA-REQ) message structure. The diagram shows a 32-bit message (bits 0 to 31) with a MAC management message header (bits 0-31), a Transaction ID (bits 0-15), and TLV encoded information (bits 16-31).](51501a01b2c29ac95e126882508f8831_img.jpg)
+
+The diagram illustrates the structure of a DSA-REQ message. It is a 32-bit message with the following fields:
+
+- MAC management message header:** Bits 0 to 31. This field is shown with break symbols at the ends, indicating it may be split across multiple bytes.
+- Transaction ID:** Bits 0 to 15. This is a 16-bit field.
+- TLV encoded information:** Bits 16 to 31. This is a 16-bit field.
+
+The diagram is labeled J.122\_F8-30.
+
+Diagram of a Dynamic service addition request (DSA-REQ) message structure. The diagram shows a 32-bit message (bits 0 to 31) with a MAC management message header (bits 0-31), a Transaction ID (bits 0-15), and TLV encoded information (bits 16-31).
+
+Figure 8-30 – Dynamic service addition request
+
+A CM or CMTS MUST generate DSA-REQ messages in the form shown in Figure 8-30, including the following parameter:
+
+- **Transaction ID:** Unique identifier for this transaction assigned by the sender.
+
+All other parameters are coded as TLV tuples as defined in Annex C.
+
+A DSA-REQ message MUST NOT contain parameters for more than one service flow in each direction, i.e., a DSA-REQ message MUST contain parameters for either a single upstream service flow, or for a single downstream service flow, or for one upstream and one downstream service flow.
+
+The DSA-REQ message MUST contain:
+
+- **Service flow parameters:** Specification of the service flow's traffic characteristics and scheduling requirements.
+
+The DSA-REQ message MAY contain classifier parameters and payload header suppression parameters associated with the service flows specified in the message:
+
+- **Classifier parameters:** Specification of the rules to be used to classify packets into a specific service flow.
+
+- **Payload header suppression parameters:** Specification of the payload header suppression rules to be used with an associated classifier.
+
+If privacy is enabled, the DSA-REQ message MUST contain:
+
+- **Key sequence number:** The key sequence number of the auth key, which is used to calculate the HMAC-Digest (refer to clause C.1.4.3).
+- **HMAC-Digest:** The HMAC-Digest attribute is a keyed message digest (to authenticate the sender). The HMAC-Digest attribute MUST be the final attribute in the dynamic service message's attribute list (refer to clause C.1.4.1).
+
+#### 8.3.12.1 CM-initiated dynamic service addition
+
+CM-initiated DSA-Requests MUST use the service flow reference to link classifiers to service flows. Values of the service flow reference are local to the DSA message; each service flow within the DSA-Request MUST be assigned a unique service flow reference. This value need not be unique with respect to the other service flows known by the sender.
+
+CM-initiated DSA-Request MUST use the classifier reference and service flow reference to link payload header suppression parameters to classifiers and service flows. A DSA-Request MUST use the service flow reference to link classifier to service flow. Values of the classifier reference are local to the DSA message; each classifier within the DSA-Request MUST be assigned a unique classifier reference.
+
+CM-initiated DSA-Requests MAY use the service class name (refer to clause C.2.2.3.4) in place of some, or all, of the QoS parameters.
+
+#### 8.3.12.2 CMTS-initiated dynamic service addition
+
+CMTS-initiated DSA-Requests MUST use the service flow ID to link classifiers to service flows. Service flow identifiers are unique within the MAC domain. CMTS-initiated DSA-Requests for upstream service flows MUST also include a service ID.
+
+CMTS-initiated DSA-Requests which include classifiers, MUST assign a unique classifier identifier on a per service flow basis.
+
+CMTS-initiated DSA-Requests for named service classes MUST include the QoS parameter set associated with that service class.
+
+### 8.3.13 Dynamic service addition response (DSA-RSP)
+
+A dynamic service addition response MUST be generated in response to a received DSA-Request. The format of a DSA-RSP MUST be as shown in Figure 8-31.
+
+![Diagram of Dynamic service addition response message structure. The diagram shows a 32-bit message (bits 0 to 31). The top section is the 'MAC management message header' (bits 0-31). Below it, the first 16 bits (bits 0-15) are split into 'Transaction ID' (bits 0-7) and 'Confirmation code' (bits 8-15). The remaining 16 bits (bits 16-31) are 'TLV encoded information'. A label 'J.122_F8-31' is at the bottom right.](43f7b6b61db9a2f3e3920740a9527d97_img.jpg)
+
+Bit 0 8 16 24 31
+
+MAC management message header
+
+Transaction ID Confirmation code
+
+TLV encoded information
+
+J.122\_F8-31
+
+Diagram of Dynamic service addition response message structure. The diagram shows a 32-bit message (bits 0 to 31). The top section is the 'MAC management message header' (bits 0-31). Below it, the first 16 bits (bits 0-15) are split into 'Transaction ID' (bits 0-7) and 'Confirmation code' (bits 8-15). The remaining 16 bits (bits 16-31) are 'TLV encoded information'. A label 'J.122\_F8-31' is at the bottom right.
+
+**Figure 8-31 – Dynamic service addition response**
+
+Parameters MUST be as follows:
+
+- **Transaction ID:** Transaction ID from corresponding DSA-REQ.
+- **Confirmation code:** The appropriate confirmation code (refer to clause C.4) for the entire corresponding DSA-Request.
+
+All other parameters are coded as TLV tuples as defined in Annex C.
+
+If the transaction is successful, the DSA-RSP MAY contain one or more of the following:
+
+- **Classifier parameters:** The CMTS MUST include the complete specification of the classifier in the DSA-RSP, including a newly assigned classifier identifier. The CM MUST NOT include the specification of the classifier in the DSA-RSP.
+- **Service flow parameters:** The CMTS MUST include the complete specification of the service flow in the DSA-RSP, including a newly assigned service flow identifier and an expanded service class name if applicable. The CM MUST NOT include the specification of the service flow in the DSA-RSP.
+- **Payload header suppression parameters:** The CMTS MUST include the complete specification of the PHS parameters in the DSA-RSP, including a newly assigned PHS index, a classifier identifier and a service flow identifier. The CM MUST NOT include the specification of the PHS parameters.
+
+If the transaction is unsuccessful due to service flow parameters, classifier parameters or payload header suppression parameters, and the confirmation code is not one of the major error codes in clause C.4.2, the DSA-RSP MUST contain at least one of the following:
+
+- **Service flow error set:** A service flow error set and identifying service flow reference/identifier MUST be included for at least one failed service flow in the corresponding DSA-REQ. Every service flow error set MUST include at least one specific failed QoS parameter of the corresponding service flow. This parameter MUST be omitted if the entire DSA-REQ is successful.
+- **Classifier error set:** A classifier error set and identifying classifier reference/identifier and service flow reference/identifier pair MUST be included for at least one failed classifier in the corresponding DSA-REQ. Every classifier error set MUST include at least one specific failed classifier parameter of the corresponding classifier. This parameter MUST be omitted if the entire DSA-REQ is successful.
+
+- **Payload header suppression error set:** A PHS error set and identifying classifier reference/identifier and service flow reference/identifier pair MUST be included for at least one failed PHS rule in the corresponding DSA-REQ. Every PHS error set MUST include at least one specific failed PHS parameter of the corresponding failed PHS rule. This parameter MUST be omitted if the entire DSA-REQ is successful.
+
+If privacy is enabled, the DSA-RSP message MUST contain:
+
+- **Key sequence number:** The key sequence number of the auth key, which is used to calculate the HMAC-Digest (refer to clause C.1.4.3).
+- **HMAC-Digest:** The HMAC-Digest attribute is a keyed message digest (to authenticate the sender). The HMAC-Digest attribute MUST be the final attribute in the dynamic service message's attribute list (refer to clause C.1.4.1).
+
+#### 8.3.13.1 CM-initiated dynamic service addition
+
+The CMTS's DSA-Response for service flows that are successfully added MUST contain a service flow ID. The DSA-Response for successfully admitted or active upstream QoS parameter sets MUST also contain a service ID.
+
+If the corresponding DSA-Request uses the service class name (refer to clause C.2.2.3.4) to request service addition, a DSA-Response MUST contain the QoS parameter set associated with the named service class. If the service class name is used in conjunction with other QoS parameters in the DSA-Request, the CMTS MUST accept or reject the DSA-Request using the explicit QoS parameters in the DSA-Request. If these service flow encodings conflict with the service class attributes, the CMTS MUST use the DSA-Request values as overrides for those of the service class.
+
+If the transaction is successful, the CMTS MUST assign a classifier identifier to each requested classifier and a PHS index to each requested PHS rule. The CMTS MUST use the original classifier reference(s) and service flow reference(s) to link the successful parameters in the DSA-RSP.
+
+If the transaction is unsuccessful, the CMTS MUST use the original classifier reference(s) and service flow reference(s) to identify the failed parameters in the DSA-RSP.
+
+#### 8.3.13.2 CMTS-initiated dynamic service addition
+
+If the transaction is unsuccessful, the CM MUST use the classifier identifier(s) and service flow identifier(s) to identify the failed parameters in the DSA-RSP.
+
+### 8.3.14 Dynamic service addition acknowledge (DSA-ACK)
+
+A dynamic service addition acknowledge MUST be generated in response to a received DSA-RSP. The format of a DSA-ACK MUST be as shown in Figure 8-32.
+
+![Diagram of Dynamic service addition acknowledge message structure. The message is 32 bits (0-31) long. The first 32 bits are the MAC management message header. The next 32 bits are split into Transaction ID (bits 0-15) and Confirmation code (bits 16-31). The remaining bits are TLV encoded information.](ce06eec6bb6d76bf7688932b2f6eb6fa_img.jpg)
+
+Bit 0 8 16 24 31
+
+|                               |  |                   |  |
+|-------------------------------|--|-------------------|--|
+| MAC management message header |  |                   |  |
+| Transaction ID                |  | Confirmation code |  |
+| TLV encoded information       |  |                   |  |
+
+J.122\_F8-32
+
+Diagram of Dynamic service addition acknowledge message structure. The message is 32 bits (0-31) long. The first 32 bits are the MAC management message header. The next 32 bits are split into Transaction ID (bits 0-15) and Confirmation code (bits 16-31). The remaining bits are TLV encoded information.
+
+**Figure 8-32 – Dynamic service addition acknowledge**
+
+Parameters MUST be as follows:
+
+- **Transaction ID:** Transaction ID from corresponding DSA-Response.
+- **Confirmation code:** The appropriate confirmation code (refer to clause C.4) for the entire corresponding DSA-Response<sup>16</sup>.
+
+All other parameters are coded TLV tuples.
+
+- **Service flow error set:** The service flow error set of the DSA-ACK message encodes specifics of failed service flows in the DSA-RSP message. A service flow error set and identifying service flow reference/identifier MUST be included for at least one failed QoS parameter of at least one failed service flow in the corresponding DSA-REQ. This parameter MUST be omitted if the entire DSA-REQ is successful.
+
+If privacy is enabled, the DSA-RSP message MUST contain:
+
+- **Key sequence number:** The key sequence number of the auth key, which is used to calculate the HMAC-Digest (refer to clause C.1.4.3).
+- **HMAC-Digest:** The HMAC-Digest attribute is a keyed message digest (to authenticate the sender). The HMAC-Digest attribute MUST be the final attribute in the dynamic service message's attribute list (refer to clause C.1.4.1).
+
+### 8.3.15 Dynamic service change request (DSC-REQ)
+
+A dynamic service change request MAY be sent by a CM or CMTS to dynamically change the parameters of an existing service flow. DSCs changing classifiers MUST carry the entire classifier TLV set for that new classifier.
+
+<sup>16</sup> The confirmation code is necessary particularly when a service class name (refer to clause 10.1.3) is used in the DSA-Request. In this case, the DSA-Response could contain service flow parameters that the CM is unable to support (either temporarily or as configured).
+
+![Diagram of a Dynamic service change request message structure. The message is 32 bits (0-31) long. The first 32 bits are the MAC management message header. The next 32 bits are the Transaction ID. The remaining bits are TLV encoded information.](2cc98b619abc7a0e53aac9c44226ca89_img.jpg)
+
+The diagram shows the structure of a Dynamic service change request message. It is a 32-bit word structure. The first 32 bits (0-31) are the MAC management message header. The next 32 bits (32-63) are the Transaction ID. The remaining bits (64-95) are TLV encoded information. The diagram is labeled J.122\_F8-33.
+
+Diagram of a Dynamic service change request message structure. The message is 32 bits (0-31) long. The first 32 bits are the MAC management message header. The next 32 bits are the Transaction ID. The remaining bits are TLV encoded information.
+
+**Figure 8-33 – Dynamic service change request**
+
+A CM or CMTS MUST generate DSC-REQ messages in the form shown in Figure 8-33 including the following parameters:
+
+- **Transaction ID:** Unique identifier for this transaction assigned by the sender.
+
+All other parameters are coded as TLV tuples as defined in Annex C.
+
+A DSC-REQ message MUST NOT carry parameters for more than one service flow in each direction, i.e., a DSC-REQ message MUST contain parameters for either a single upstream service flow, or for a single downstream service flow, or for one upstream and one downstream service flow. A DSC-REQ MUST contain at least one of the following:
+
+- **Classifier parameters:** Specification of the rules to be used to classify packets into a specific service flow – this includes the dynamic service change action TLV which indicates whether this classifier should be added, replaced or deleted from the service flow (refer to clause C.2.1.3.7). If included, the classifier parameters MUST contain the dynamic change action TLV, a classifier reference/identifier and a service flow identifier.
+- **Service flow parameters:** Specification of the service flow's new traffic characteristics and scheduling requirements. The admitted and active quality of service parameter sets in this message replace the admitted and active quality of service parameter sets currently in use by the service flow. If the DSC message is successful and it contains service flow parameters, but does not contain replacement sets for both admitted and active quality of service parameter sets, the omitted set(s) MUST be set to null. If included, the service flow parameters MUST contain a service flow identifier.
+- **Payload header suppression parameters:** Specification of the rules to be used for payload header suppression to suppress payload headers related to a specific classifier – this includes the dynamic service change action TLV which indicates whether this PHS rule should be added, set or deleted from the service flow or whether all the PHS rules for the service flow specified should be deleted (refer to clause C.2.2.8.5). If included, the PHS parameters MUST contain the dynamic service change action TLV, a classifier reference/identifier and a service flow identifier, unless the dynamic service change action is "delete all PHS rules". If the dynamic service change action is "delete all PHS rules", the PHS parameters MUST contain a service flow identifier along with the dynamic service change action, and no other PHS parameters need be present in this case. However, if other
+
+PHS parameters are present, in particular payload header suppression index, they MUST be ignored by the receiver of the DSC-REQ message.
+
+If privacy is enabled, a DSC-REQ MUST also contain:
+
+- **Key sequence number:** The key sequence number of the auth key, which is used to calculate the HMAC-Digest (refer to clause C.1.4.3).
+- **HMAC-Digest:** The HMAC-Digest attribute is a keyed message digest (to authenticate the sender). The HMAC-Digest attribute MUST be the final attribute in the dynamic service message's attribute list (refer to clause C.1.4.1).
+
+### 8.3.16 Dynamic service change response (DSC-RSP)
+
+A dynamic service change response MUST be generated in response to a received DSC-REQ. The format of a DSC-RSP MUST be as shown in Figure 8-34.
+
+![Diagram of Dynamic service change response (DSC-RSP) structure](8fce89f02626b8a0c50e2245bc3e7ce7_img.jpg)
+
+The diagram illustrates the structure of a DSC-RSP message. It shows a 32-bit word structure with bit positions 0, 8, 16, 24, and 31 marked at the top. The first 32-bit word is the 'MAC management message header', indicated by a double slash on its left and right sides. Below this header is the 'Transaction ID', which occupies the first 16 bits (bits 0 to 15). The remaining 16 bits of the second 32-bit word and all subsequent bits are designated as 'TLV encoded information'. The diagram is labeled 'J.122\_F8-34' at the bottom right.
+
+Diagram of Dynamic service change response (DSC-RSP) structure
+
+**Figure 8-34 – Dynamic service change response**
+
+Parameters MUST be as follows:
+
+- **Transaction ID:** Transaction ID from corresponding DSC-REQ.
+- **Confirmation code:** The appropriate confirmation code (refer to clause C.4) for the corresponding DSC-Request.
+
+All other parameters are coded as TLV tuples as defined in Annex C.
+
+If the transaction is successful, the DSC-RSP MAY contain one or more of the following:
+
+- **Classifier parameters:** The CMTS MUST include the complete specification of the classifier in the DSC-RSP, including a newly assigned classifier identifier for new classifiers. The CM MUST NOT include the specification of the classifier in the DSC-RSP.
+- **Service flow parameters:** The CMTS MUST include the complete specification of the service flow in the DSC-RSP, including an expanded service class name if applicable. The CMTS MUST include a SID in the DSC-RSP if a service flow parameter set contained an upstream admitted QoS parameter set and this service flow does not have an associated SID. If a service flow parameter set contained a service class name and an admitted QoS parameter set, the CMTS MUST include the QoS parameter set corresponding to the named service class in the DSC-RSP. If specific QoS parameters were also included in the classed service flow request, the CMTS MUST include these QoS parameters in the DSC-RSP
+
+instead of any QoS parameters of the same type of the named service class. The CM MUST NOT include the specification of the service flow in the DSC-RSP.
+
+- **Payload header suppression parameters:** The CMTS MUST include the complete specification of the PHS parameters in the DSC-RSP, including a newly assigned PHS index for new PHS rules, a classifier identifier and a service flow identifier. The CM MUST NOT include the specification of the PHS parameters.
+
+If the transaction is unsuccessful due to service flow parameters, classifier parameters or payload header suppression parameters, and the confirmation code is not one of the major error codes in clause C.4.2, the DSC-RSP MUST contain at least one of the following:
+
+- **Classifier error set:** A classifier error set and identifying classifier reference/identifier and service flow reference/identifier pair MUST be included for at least one failed classifier in the corresponding DSC-REQ. Every classifier error set MUST include at least one specific failed classifier parameter of the corresponding classifier. This parameter MUST be omitted if the entire DSC-REQ is successful.
+- **Service flow error set:** A service flow error set and identifying service flow ID MUST be included for at least one failed service flow in the corresponding DSC-REQ. Every service flow error set MUST include at least one specific failed QoS parameter of the corresponding service flow. This parameter MUST be omitted if the entire DSC-REQ is successful.
+- **Payload header suppression error set:** A PHS error set and identifying service flow reference/identifier and classifier reference/identifier pair MUST be included for at least one failed PHS rule in the corresponding DSC-REQ, unless the dynamic service change action is "delete all PHS rules". If the dynamic service change action is "delete all PHS rules" the PHS error set(s) MUST include an identifying service flow ID. Every PHS error set MUST include at least one specific failed PHS parameter of the corresponding failed PHS rule. This parameter MUST be omitted if the entire DSC-REQ is successful.
+
+Regardless of success or failure, if privacy is enabled for the CM, the DSC-RSP MUST contain:
+
+- **Key sequence number:** The key sequence number of the auth key, which is used to calculate the HMAC-Digest (refer to clause C.1.4.3).
+- **HMAC-Digest:** The HMAC-Digest attribute is a keyed message digest (to authenticate the sender). The HMAC-Digest attribute MUST be the final attribute in the dynamic service message's attribute list (refer to clause C.1.4.1).
+
+### 8.3.17 Dynamic service change acknowledge (DSC-ACK)
+
+A dynamic service change acknowledge MUST be generated in response to a received DSC-RSP. The format of a DSC-ACK MUST be as shown in Figure 8-35.
+
+![Diagram of Dynamic service change acknowledge message structure. The diagram shows a 32-bit message structure. The top section is the 'MACmanagement message header' (bits 0-31). Below it, the first 16 bits are split into 'Transaction ID' (bits 0-8) and 'Confirmation code' (bits 9-16). The remaining 16 bits (bits 17-31) are 'TLV encoded information'. A break symbol (double wavy line) is shown in the header section. The diagram is labeled 'J.122_F8-35' at the bottom right.](40d0aaaa3afa0a9fabe637941ca250bb_img.jpg)
+
+Diagram of Dynamic service change acknowledge message structure. The diagram shows a 32-bit message structure. The top section is the 'MACmanagement message header' (bits 0-31). Below it, the first 16 bits are split into 'Transaction ID' (bits 0-8) and 'Confirmation code' (bits 9-16). The remaining 16 bits (bits 17-31) are 'TLV encoded information'. A break symbol (double wavy line) is shown in the header section. The diagram is labeled 'J.122\_F8-35' at the bottom right.
+
+**Figure 8-35 – Dynamic service change acknowledge**
+
+Parameters MUST be as follows:
+
+- **Transaction ID:** Transaction ID from the corresponding DSC-REQ.
+- **Confirmation code:** The appropriate confirmation code (refer to clause C.4) for the entire corresponding DSC-Response<sup>17</sup>.
+
+All other parameters are coded as TLV tuples.
+
+- **Service flow error set:** The service flow error set of the DSC-ACK message encodes specifics of failed service flows in the DSC-RSP message. A service flow error set and identifying service flow identifier MUST be included for at least one failed QoS parameter of at least one failed service flow in the corresponding DSC-REQ. This parameter MUST be omitted if the entire DSC-REQ is successful.
+
+If privacy is enabled, the DSC-ACK message MUST contain:
+
+- **Key sequence number:** The key sequence number of the auth key, which is used to calculate the HMAC-Digest (refer to clause C.1.4.3).
+- **HMAC-Digest:** The HMAC-Digest attribute is a keyed message digest (to authenticate the sender). The HMAC-Digest attribute MUST be the final attribute in the dynamic service message's attribute list (refer to clause C.1.4.1).
+
+### 8.3.18 Dynamic service deletion request (DSD-REQ)
+
+A dynamic service deletion request MAY be sent by a CM or CMTS to delete a single existing upstream service flow and/or a single existing downstream service flow. The format of a DSD-Request MUST be as shown in Figure 8-36.
+
+<sup>17</sup> The confirmation code and service flow error set are necessary particularly when a service class name (refer to clause 10.1.3) is used in the DSC-Request. In this case, the DSC-Response could contain service flow parameters that the CM is unable to support (either temporarily or as configured).
+
+![Diagram of Dynamic service deletion request (DSD-REQ) message structure. The diagram shows a 32-bit (0-31) message format. The first part is a 'MAC management message header' (bits 0-31). Below it is a 16-bit 'Transaction ID' (bits 0-15) and a 16-bit 'Reserved' field (bits 16-31). The next part is a 32-bit 'SFID' (bits 0-31). The final part is 'TLV encoded information' (bits 0-31). The diagram is labeled J.122_F8-36.](b5ce6d659e1431289c2e79b01bf38a15_img.jpg)
+
+Bit 0 8 16 24 31
+
+|                               |  |          |  |
+|-------------------------------|--|----------|--|
+| MAC management message header |  |          |  |
+| Transaction ID                |  | Reserved |  |
+| SFID                          |  |          |  |
+| TLV encoded information       |  |          |  |
+
+J.122\_F8-36
+
+Diagram of Dynamic service deletion request (DSD-REQ) message structure. The diagram shows a 32-bit (0-31) message format. The first part is a 'MAC management message header' (bits 0-31). Below it is a 16-bit 'Transaction ID' (bits 0-15) and a 16-bit 'Reserved' field (bits 16-31). The next part is a 32-bit 'SFID' (bits 0-31). The final part is 'TLV encoded information' (bits 0-31). The diagram is labeled J.122\_F8-36.
+
+**Figure 8-36 – Dynamic service deletion request**
+
+Parameters MUST be as follows:
+
+- **Service flow identifier:** If this value is non-zero, it is the SFID of a single upstream or single downstream service flow to be deleted. If this value is zero, the service flow(s) to be deleted will be identified by SFID(s) in the TLVs. If this value is non-zero, any SFIDs included in the TLVs MUST be ignored.
+- **Transaction ID:** Unique identifier for this transaction assigned by the sender.
+
+All other parameters are coded as TLV tuples as defined in Annex C.
+
+- **Service flow identifier:** The SFID(s) to be deleted, which MUST be encoded per clause C.2.2.3.2. The service flow identifier TLV MUST be the only service flow encoding sub-TLV used.
+
+If privacy is enabled, the DSD-REQ MUST include:
+
+- **Key sequence number:** The key sequence number of the auth key, which is used to calculate the HMAC-Digest (refer to clause C.1.4.3).
+- **HMAC-Digest:** The HMAC-Digest attribute is a keyed message digest (to authenticate the sender). The HMAC-Digest attribute MUST be the final attribute in the dynamic service message's attribute list (refer to clause C.1.4.1).
+
+### **8.3.19 Dynamic service deletion response (DSD-RSP)**
+
+A dynamic service deletion response MUST be generated in response to a received DSD-REQ. The format of a DSD-RSP MUST be as shown in Figure 8-37.
+
+![Diagram of Dynamic service deletion response message structure. It shows a 32-bit word with bit positions 0, 8, 16, 24, and 31. The top part is the MAC management message header. The bottom part is divided into three fields: Transaction ID (bits 0-15), Confirmation code (bits 16-23), and Reserved (bits 24-31).](54f73f693f36dcbd300fa21ac4e410e8_img.jpg)
+
+|                               |                   |          |  |
+|-------------------------------|-------------------|----------|--|
+| Bit 0 8 16 24 31              |                   |          |  |
+| MAC management message header |                   |          |  |
+| Transaction ID                | Confirmation code | Reserved |  |
+
+Diagram of Dynamic service deletion response message structure. It shows a 32-bit word with bit positions 0, 8, 16, 24, and 31. The top part is the MAC management message header. The bottom part is divided into three fields: Transaction ID (bits 0-15), Confirmation code (bits 16-23), and Reserved (bits 24-31).
+
+J.122\_F8-37
+
+**Figure 8-37 – Dynamic service deletion response**
+
+Parameters MUST be as follows:
+
+- **Transaction ID:** Transaction ID from corresponding DSD-REQ.
+- **Confirmation Code:** The appropriate confirmation code (refer to clause C.4) for the corresponding DSD-Request.
+
+**8.3.20 Dynamic channel change request (DCC-REQ)**
+
+A dynamic channel change request MAY be transmitted by a CMTS to cause a CM to change the upstream channel on which it is transmitting, the downstream channel on which it is receiving, or both.
+
+![Diagram of Dynamic channel change request message structure. It shows a 32-bit word with bit positions 0, 8, 16, 24, and 31. The top part is the MAC management message header. Below it is the Transaction ID (bits 0-15). The remaining part (bits 16-31) is TLV encoded information.](4a0766e76be1050af738d0a7e9e5c9fb_img.jpg)
+
+|                               |                         |  |  |
+|-------------------------------|-------------------------|--|--|
+| Bit 0 8 16 24 31              |                         |  |  |
+| MAC management message header |                         |  |  |
+| Transaction ID                | TLV encoded information |  |  |
+
+Diagram of Dynamic channel change request message structure. It shows a 32-bit word with bit positions 0, 8, 16, 24, and 31. The top part is the MAC management message header. Below it is the Transaction ID (bits 0-15). The remaining part (bits 16-31) is TLV encoded information.
+
+J.122\_F8-38
+
+**Figure 8-38 – Dynamic channel change request**
+
+A CMTS MUST generate DCC-REQ message in the form shown in Figure 8-38, including the following parameters:
+
+- **Transaction ID:** A 16-bit unique identifier for this transaction assigned by the sender.
+
+The following parameters are optional and are coded as TLV tuples:
+
+- **Upstream channel ID:** The identifier of the upstream channel to which the CM is to switch for upstream transmissions.
+- **Downstream parameters:** The frequency of the downstream channel to which the CM is to switch for downstream reception.
+
+- **Initialization technique:** Directions for the type of initialization, if any, that the CM should perform once synchronized to the new channel(s).
+- **UCD substitution:** Provides a copy of the UCD for the new channel. This TLV occurs as many times as necessary to contain one UCD.
+- **SAID substitution:** A pair of security association identifiers (SAID) which contain the current SAID and the new SAID for the new channel. This TLV occurs once if the SAID requires substitution.
+- **Service flow substitution:** A group of sub-TLVs which allows substitution in a service flow of the service flow identifier and service identifier. This TLV is repeated for every service flow which has parameters requiring substitution.
+
+If privacy is enabled, a DCC-REQ MUST also contain:
+
+- **Key sequence number:** The key sequence number of the auth key, which is used to calculate the HMAC-Digest (refer to clause C.1.4.3).
+- **HMAC-Digest:** The HMAC-Digest attribute is a keyed message digest (to authenticate the sender). The HMAC-Digest attribute MUST be the final attribute in the dynamic channel change message's attribute list (refer to clause C.1.4.1).
+
+### 8.3.20.1 Encodings
+
+The type values used MUST be those shown below. These are unique within the dynamic channel change request message, but not across the entire MAC message set.
+
+#### 8.3.20.1.1 Upstream channel ID
+
+When present, this TLV specifies the new upstream channel ID that the CM MUST use when performing a dynamic channel change. It is an override for the current upstream channel ID. The CMTS SHOULD ensure that the upstream channel ID for the new channel is different from the upstream channel ID for the old channel. This TLV MUST be included if the upstream channel is changed, even if the UCD substitution TLV is included.
+
+| Type | Length | Value                      |
+|------|--------|----------------------------|
+| 1    | 1      | 0-255: Upstream channel ID |
+
+If this TLV is missing, the CM MUST NOT change its upstream channel ID. The CMTS MAY include this TLV. The CM MUST observe this TLV.
+
+#### 8.3.20.1.2 Downstream parameters
+
+When present, this TLV specifies the operating parameters of the new downstream channel. The value field of this TLV contains a series of subtypes.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 2    | n      |       |
+
+The CMTS MUST include this TLV when specifying a downstream channel change. If this TLV is missing, the CM MUST NOT change its downstream parameters.
+
+##### 8.3.20.1.2.1 Downstream frequency
+
+This TLV specifies the new receive frequency that the CM MUST use when performing a dynamic channel change. It is an override for the current downstream channel frequency. This is the centre frequency of the downstream channel in Hz and is stored as a 32-bit binary number. The downstream frequency MUST be a multiple of 62 500 Hz.
+
+| Subtype | Length | Value        |
+|---------|--------|--------------|
+| 2.1     | 4      | Rx frequency |
+
+The CMTS MUST include this sub-TLV. The CM MUST observe this sub-TLV.
+
+#### 8.3.20.1.2.2 Downstream modulation type
+
+This TLV specifies the modulation type that is used on the new downstream channel.
+
+| Subtype | Length | Value                                    |
+|---------|--------|------------------------------------------|
+| 2.2     | 1      | 0: 64QAM<br>1: 256QAM<br>2-255: Reserved |
+
+The CMTS SHOULD include this sub-TLV. The CM SHOULD observe this sub-TLV.
+
+#### 8.3.20.1.2.3 Downstream symbol rate
+
+This TLV specifies the symbol rate that is used on the new downstream channel.
+
+| Subtype | Length | Value                                                                             |
+|---------|--------|-----------------------------------------------------------------------------------|
+| 2.3     | 1      | 0: 5.056941 Msymb/s<br>1: 5.360537 Msymb/s<br>2: 6.952 Msymb/s<br>3-255: Reserved |
+
+The CMTS SHOULD include this sub-TLV. The CM SHOULD observe this sub-TLV.
+
+#### 8.3.20.1.2.4 Downstream interleaver depth
+
+This TLV specifies the parameters "I" and "J" of the downstream interleaver.
+
+| Subtype | Length | Value                |
+|---------|--------|----------------------|
+| 2.4     | 2      | I: 0-255<br>J: 0-255 |
+
+The CMTS SHOULD include this sub-TLV. The CM SHOULD observe this sub-TLV.
+
+#### 8.3.20.1.2.5 Downstream channel identifier
+
+This TLV specifies the 8-bit downstream channel identifier of the new downstream channel.
+
+| Subtype | Length | Value                        |
+|---------|--------|------------------------------|
+| 2.5     | 1      | 0-255: Downstream channel ID |
+
+The CMTS SHOULD include this sub-TLV. The CM SHOULD observe this sub-TLV.
+
+#### 8.3.20.1.2.6 SYNC Substitution
+
+When present, this TLV allows the CMTS to inform the CM to wait or not wait for a SYNC message before proceeding. The CMTS MUST have synchronized timestamps between the old and new channel(s) if it instructs the CM not to wait for a SYNC message before transmitting on the new channel. Synchronized timestamps implies that the timestamps are derived from the same clock and contain the same value.
+
+| Subtype | Length | Value                                                                                                                                             |
+|---------|--------|---------------------------------------------------------------------------------------------------------------------------------------------------|
+| 2.6     | 1      | 0: Acquire SYNC message on the new downstream channel before proceeding<br>1: Proceed without first obtaining the SYNC message<br>2-255: Reserved |
+
+If this TLV is absent, the CM MUST wait for a SYNC message on the new channel before proceeding. If the CM has to wait for a new SYNC message when changing channels, then operation may be suspended for a time up to the "SYNC interval" (see Annex B) or longer, if the SYNC message is lost or is not synchronized with the old channel(s).
+
+The CM MUST observe this TLV.
+
+### 8.3.20.1.3 Initialization technique
+
+When present, this TLV allows the CMTS to direct the CM as to what level of re-initialization, if any, it MUST perform before it can commence communications on the new channel(s). The CMTS can make this decision based upon its knowledge of the differences between the old and new MAC domains and the PHY characteristics of their upstream and downstream channels.
+
+Typically, if the move is between upstream and/or downstream channels within the same MAC domain, then the connection profile values may be left intact. If the move is between different MAC domains, then a complete initialization may be performed.
+
+If a complete re-initialization is not required, some re-ranging may still be required. For example, areas of upstream spectrum are often configured in groups. A DCC-REQ to an adjacent upstream channel within a group may not warrant re-ranging. Alternatively, a DCC-REQ to a non-adjacent upstream channel might require unicast initial ranging whereas a DCC-REQ from one upstream channel group to another might require broadcast initial ranging. Re-ranging may also be required if there is any difference in the PHY parameters between the old and new channels.
+
+| Subtype | Length | Value                                                                                                                                                                                                                                                                                                                                                                                             |
+|---------|--------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 3       | 1      | 0: Re-initialize the MAC<br>1: Perform broadcast initial ranging on new channel before normal operation<br>2: Perform unicast initial ranging on new channel before normal operation<br>3: Perform either broadcast initial ranging or unicast initial ranging on new channel before normal operation<br>4: Use the new channel(s) directly without re-initializing or ranging<br>5-255: Reserved |
+
+The CM MUST first select the new upstream and downstream channels based upon the upstream channel ID TLV (refer to clause 8.3.20.1.1) and the downstream frequency TLV (refer to clause 8.3.20.1.2.1). The CM MUST follow the directives of these TLVs. For Option 0, the CM MUST begin with the initialization SID. For Options 1 to 4 the CM MUST continue to use the primary SID for ranging. A SID substitution TLV may specify a new primary SID for use on the new channel (refer to clause 8.3.20.1.6.2).
+
+- **Option 0:** This option directs the CM to perform all the operations associated with initializing the CM (refer to clause 11.2). This includes all the events after acquiring downstream QAM, FEC and MPEG lock and before standard operation (refer to clause 11.3), including obtaining a UCD, ranging, establishing IP connectivity, establishing time of day, transfer of operational parameters, registration and baseline privacy initialization. When this option is used, the only other TLVs in DCC-REQ that are relevant are the upstream channel ID TLV and the downstream parameters TLV. All other DCC-REQ TLVs are irrelevant.
+- **Option 1:** If broadcast initial ranging is specified, operation on the new channel could be delayed by several ranging intervals (see Annex B).
+- **Option 2:** If unicast initial ranging is specified, operation on the new channel could be delayed by the value of T4 (see Annex B).
+- **Option 3:** This value authorizes a CM to use an initial maintenance or station maintenance region, whichever the CM selects. This value might be used when there is uncertainty when the CM may execute the DCC command and thus a chance that it might miss station maintenance slots.
+- **Option 4:** This option provides for the least interruption of service, and the CM may continue its normal operation as soon as it has achieved synchronization on the new channel.
+
+If this TLV is absent, the CM MUST re-initialize the MAC. The CMTS MAY include this TLV. The CM MUST observe this TLV.
+
+#### 8.3.20.1.4 UCD substitution
+
+When present, this TLV allows the CMTS to send an upstream channel descriptor message to the CM. This UCD message is intended to be associated with the new upstream and/or downstream channel(s). The CM stores this UCD message in its cache, and uses it after synchronizing to the new channel(s).
+
+| Type | Length | Value                            |
+|------|--------|----------------------------------|
+| 4    | n      | UCD for the new upstream channel |
+
+This TLV includes all parameters for the UCD message as described in clause 8.3.3 except for the MAC management message header. The CMTS MUST ensure that the change count in the UCD matches the change count in the UCDs of the new channel(s). The CMTS SHOULD ensure that the upstream channel ID for the new channel is different from the upstream channel ID for the old channel. If the upstream channel IDs for the old and new channels are identical, the CMTS MUST include this TLV. The ranging required parameter in the new UCD does not apply in this context, since the functionality is covered by the initialization technique TLV.
+
+If the length of the UCD exceeds 254 bytes, the UCD MUST be fragmented into two or more successive type 4 elements. Each fragment, except the last, MUST be 254 bytes in length. The CM reconstructs the UCD substitution by concatenating the contents (value of the TLV) of successive type 4 elements in the order in which they appear in the DCC-REQ message. For example, the first byte following the length field of the second type 4 element is treated as if it immediately follows the last byte of the first type 4 element.
+
+If the CM has to wait for a new UCD message when changing channels, then operation may be suspended for a time up to the "UCD interval" (see Annex B) or longer, if the UCD message is lost.
+
+The CM MUST observe this TLV, even if the upstream channel ID and the UCD change count match the old channel.
+
+#### 8.3.20.1.5 Security association identifier (SAID) substitution
+
+When present, this TLV allows the CMTS to replace the security association identifier (SAID) in the current service flow with a new security association identifier. The baseline privacy keys associated with the SAID MUST remain the same. The CM does not have to simultaneously respond to the old and new SAID.
+
+| Subtype | Length | Value                                                                                                  |
+|---------|--------|--------------------------------------------------------------------------------------------------------|
+| 6       | 4      | Current SAID (lower-order 14 bits of a 16-bit field), new SAID (lower-order 14 bits of a 16-bit field) |
+
+If this TLV is absent, the current security association identifier assignment is retained. The CMTS MAY include this TLV. The CM MUST observe this TLV.
+
+#### 8.3.20.1.6 Service flow substitutions
+
+When present, this TLV allows the CMTS to replace specific parameters within the current service flows on the current channel assignment with new parameters for the new channel assignment. One TLV is used for each service flow that requires changes in parameters. The CMTS may choose to do this to help facilitate setting up new QoS reservations on the new channel before deleting QoS reservations on the old channel. The CM does not have to simultaneously respond to the old and new service flows.
+
+This TLV allows resource assignments and services to be moved between two independent ID value spaces and scheduling entities by changing the associated IDs and indices. ID value spaces that may differ between the two channels include the service flow identifier and the service ID. This TLV does not allow changes to service flow QoS parameters.
+
+The service class names used within the service flow ID should remain identical between the old and new channels.
+
+| Type | Length | Value            |
+|------|--------|------------------|
+| 7    | n      | List of subtypes |
+
+If this TLV is absent for a particular service flow, then the current service flow and its attributes are retained. The CMTS MAY include this TLV. The CM MUST observe this TLV.
+
+##### 8.3.20.1.6.1 Service flow identifier substitution
+
+This TLV allows the CMTS to replace the current service flow identifier (SFID) with a new service flow identifier. Refer to clause C.2.2.3.2 for usage details.
+
+This TLV MUST be present if any other service flow subtype substitutions are made. If this TLV is included and the service flow ID is not changing, then the current and new service flow ID will be set to the same value.
+
+| Subtype | Length | Value                                        |
+|---------|--------|----------------------------------------------|
+| 7.1     | 8      | Current service flow ID, new service flow ID |
+
+The CMTS MUST include this Sub-TLV. The CM MUST observe this Sub-TLV.
+
+##### 8.3.20.1.6.2 Service identifier substitution
+
+When present, this TLV allows the CMTS to replace the service identifier (SID) in the current upstream service flow with a new service identifier. Refer to clause C.2.2.3.3 for usage details.
+
+| Subtype | Length | Value                                                                                                   |
+|---------|--------|---------------------------------------------------------------------------------------------------------|
+| 7.2     | 4      | Current SID (lower-order 14 bits of a 16-bit field),<br>new SID (lower-order 14 bits of a 16-bit field) |
+
+If this TLV is absent, the current service identifier assignments are retained. The CMTS MAY include this TLV. The CM MUST observe this TLV.
+
+#### 8.3.20.1.6.3 Unsolicited grant time reference substitution
+
+When present, this TLV allows the CMTS to replace the current unsolicited grant time reference with a new unsolicited grant time reference. Refer to clause C.2.2.6.11 for usage details.
+
+This TLV is useful if the old and new upstream use different time bases for their timestamps. This TLV is also useful if the unsolicited grant transmission window is moved to a different point in time. Changing this value may cause operation to temporarily exceed the jitter window specified by clause C.2.2.6.8.
+
+| Subtype | Length | Value         |
+|---------|--------|---------------|
+| 7.5     | 4      | New reference |
+
+If this TLV is absent, the current unsolicited grant time reference is retained. The CMTS MAY include this TLV. The CM MUST observe this TLV.
+
+#### 8.3.20.1.7 CMTS MAC address
+
+When present, this TLV allows the current CMTS to send the MAC address of the destination CMTS corresponding to the target downstream frequency.
+
+| Type | Length | Value                           |
+|------|--------|---------------------------------|
+| 8    | 6      | MAC address of destination CMTS |
+
+The CMTS MUST include this TLV if the CM is changing downstream channels and UCD substitution is specified or if the CM is changing downstream channels and using initialization technique 4. The CM SHOULD observe this TLV.
+
+### 8.3.21 Dynamic channel change response (DCC-RSP)
+
+A dynamic channel change response MUST be transmitted by a CM in response to a received dynamic channel change request message to indicate that it has received and is complying with the DCC-REQ. The format of a DCC-RSP message MUST be as shown in Figure 8-39.
+
+![Diagram of the Dynamic channel change response message structure. The message is 32 bits (0-31) long. The first 32 bits are the MAC management message header. The next 24 bits are divided into Transaction ID (16 bits) and Confirmation code (8 bits). The remaining 8 bits are TLV encoded information. The diagram shows the header, Transaction ID, Confirmation code, and TLV encoded information. The label J.122_F8-39 is at the bottom right.](f5f5c0161d7d582a5a4c7227eb4e8eb0_img.jpg)
+
+Bit 0 8 16 24 31
+
+|                               |                   |  |
+|-------------------------------|-------------------|--|
+| MAC management message header |                   |  |
+| Transaction ID                | Confirmation code |  |
+| TLV encoded information       |                   |  |
+
+J.122\_F8-39
+
+Diagram of the Dynamic channel change response message structure. The message is 32 bits (0-31) long. The first 32 bits are the MAC management message header. The next 24 bits are divided into Transaction ID (16 bits) and Confirmation code (8 bits). The remaining 8 bits are TLV encoded information. The diagram shows the header, Transaction ID, Confirmation code, and TLV encoded information. The label J.122\_F8-39 is at the bottom right.
+
+**Figure 8-39 – Dynamic channel change response**
+
+Before it begins to switch to a new upstream or downstream channel, a CM MUST transmit a DCC-RSP on its existing upstream channel. When a CM receives a DCC-REQ message requesting that it switch to an upstream and downstream channel that it is already using or requesting that it switch to only an upstream or downstream channel that it is already using, the CM MUST respond with a DCC-RSP message on that channel indicating that it is already using the correct channel.
+
+A CM MAY ignore a DCC-REQ message while it is in the process of performing a channel change.
+
+After switching to a new channel, if the MAC was not re-initialized per DCC-REQ initialization TLV, option 0, the CM MUST send a DCC-RSP message to the CMTS. A DCC-RSP MUST NOT be sent if the CM re-initializes its MAC.
+
+The full procedure for changing channels is described in clause 11.4.5.
+
+Parameters MUST be as follows:
+
+- **Transaction ID:** A 16-bit transaction ID from corresponding DCC-REQ.
+- **Confirmation code:** An 8-bit confirmation code as described in clause C.4.1.
+
+The following parameters are optional and are coded as TLV tuples:
+
+- **CM jump time:** Timing parameters describing when the CM will make the jump.
+
+Regardless of success or failure, if privacy is enabled for the CM, the DCC-RSP MUST contain:
+
+- **Key sequence number:** The key sequence number of the auth key, which is used to calculate the HMAC-Digest (refer to clause C.1.4.3).
+- **HMAC-Digest:** The HMAC-Digest attribute is a keyed message digest (to authenticate the sender). The HMAC-Digest attribute MUST be the final attribute in the dynamic channel change message's attribute list (refer to clause C.1.4.1).
+
+### 8.3.21.1 Encodings
+
+The type values used MUST be those shown below. These are unique within the dynamic channel change response message, but not across the entire MAC message set.
+
+#### 8.3.21.1.1 CM jump time
+
+When present, this TLV allows the CM to indicate to the CMTS when the CM plans to perform its jump and be disconnected from the network. With this information, the CMTS MAY take
+
+preventative measures to minimize or to eliminate packet drops in the downstream due to the channel change.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 1    | n      |       |
+
+The time reference and units of time for these sub-TLVs is based upon the same 32-bit time base used in the SYNC message on the current downstream channel. This timestamp is incremented by a 10.24-MHz clock.
+
+The CM SHOULD include this TLV. The CMTS SHOULD observe this TLV.
+
+#### 8.3.21.1.1.1 Length of jump
+
+This TLV indicates to the CMTS the length of the jump from the previous channel to the new channel. Specifically, it represents the length of time that the CM will not be able to receive data in the downstream.
+
+| Subtype | Length | Value                         |
+|---------|--------|-------------------------------|
+| 1       | 4      | Length (based upon timestamp) |
+
+The CM MUST include this sub-TLV.
+
+#### 8.3.21.1.1.2 Start time of jump
+
+When present, this TLV indicates to the CMTS the time in the future that the CM is planning on making the jump.
+
+| Subtype | Length | Value                                                                            |
+|---------|--------|----------------------------------------------------------------------------------|
+| 2       | 8      | Start time (based upon timestamp), accuracy of start time (based upon timestamp) |
+
+The 32-bit, 10.24 MHz time base rolls over approximately every 7 minutes. If the value of the start time is less than the current timestamp, the CMTS will assume one roll-over of the timestamp counter has elapsed. The accuracy of the start time is an absolute amount of time before and after the start time.
+
+The potential jump window is from (start time – accuracy) to (start time + accuracy + length).
+
+The CM SHOULD include this TLV.
+
+#### 8.3.22 Dynamic channel change acknowledge (DCC-ACK)
+
+A dynamic channel change acknowledge MUST be transmitted by a CMTS in response to a received dynamic channel change response message on the new channel with its confirmation code set to arrive(181). The format of a DCC-ACK message MUST be as shown in Figure 8-40.
+
+![Diagram of Dynamic channel change acknowledge message structure. The diagram shows a 32-bit message (bits 0 to 31). The top section is the 'MAC management message header' (bits 0-31). Below it is the 'Transaction ID' (bits 0-15). The bottom section is 'TLV encoded information' (bits 16-31). The diagram is labeled J.122_F8-40.](2fa686ed8033ac35efddee0c7be47d59_img.jpg)
+
+The diagram illustrates the structure of a 32-bit message. At the top, a box labeled 'MAC management message header' spans from bit 0 to bit 31. Below this, a box labeled 'Transaction ID' spans from bit 0 to bit 15. The bottom section, labeled 'TLV encoded information', spans from bit 16 to bit 31. The diagram is labeled J.122\_F8-40.
+
+Diagram of Dynamic channel change acknowledge message structure. The diagram shows a 32-bit message (bits 0 to 31). The top section is the 'MAC management message header' (bits 0-31). Below it is the 'Transaction ID' (bits 0-15). The bottom section is 'TLV encoded information' (bits 16-31). The diagram is labeled J.122\_F8-40.
+
+**Figure 8-40 – Dynamic channel change acknowledge**
+
+Parameters MUST be as follows:
+
+- **Transaction ID:** A 16-bit transaction ID from corresponding DCC-RSP.
+
+If privacy is enabled, the DCC-ACK message MUST contain:
+
+- **Key sequence number:** The key sequence number of the auth key, which is used to calculate the HMAC-Digest (refer to clause C.1.4.3).
+- **HMAC-Digest:** The HMAC-Digest attribute is a keyed message digest (to authenticate the sender). The HMAC-Digest attribute MUST be the final attribute in the dynamic channel change message's attribute list (refer to clause C.1.4.1).
+
+### 8.3.23 Device class identification request (DCI-REQ)
+
+A CM MAY implement the DCI-REQ message.
+
+When implemented, a CM MUST transmit a DCI-REQ immediately following receipt of a ranging complete indication from the CMTS. A CM MUST NOT continue with initialization until a DCI-RSP message is received from the CMTS. Timeout and retry information is provided in Annex B, "parameters and constants".
+
+The DCI-REQ MUST be formatted as shown in Figure 8-41.
+
+![Diagram of Device class identification request (DCI-REQ) packet structure. The packet is 32 bits long, with bit positions 0, 8, 16, 24, and 31 marked. The top section is the MAC management message header. Below it, the first 8 bits (0-7) are the SID. The next 8 bits (8-15) are the first part of the Device class field. The remaining 16 bits (16-31) are the second part of the Device class field, labeled 'Device class (cont.)'. The bottom section is the TLV encoded information.](88c92858439684b2103e88cb143fb98e_img.jpg)
+
+Bit 0 8 16 24 31
+
+MAC management message header
+
+SID Device class
+
+Device class (cont.)
+
+TLV encoded information
+
+J.122\_F8-41
+
+Diagram of Device class identification request (DCI-REQ) packet structure. The packet is 32 bits long, with bit positions 0, 8, 16, 24, and 31 marked. The top section is the MAC management message header. Below it, the first 8 bits (0-7) are the SID. The next 8 bits (8-15) are the first part of the Device class field. The remaining 16 bits (16-31) are the second part of the Device class field, labeled 'Device class (cont.)'. The bottom section is the TLV encoded information.
+
+**Figure 8-41 – Device class identification request**
+
+Parameters MUST be as follows:
+
+- **SID:** The temporary SID assigned during ranging.
+- **Device class:** This is a 32-bit field where individual bits represent individual attributes of the CM. Bit #0 is the LSB of the field. Bits are set to 1 to select the attributes defined below:
+  - bit #0: CPE controlled cable modem (CCCM).
+  - bits #1-31: Reserved and must be set to zero.
+
+**8.3.24 Device class identification response (DCI-RSP)**
+
+A DCI-RSP MUST be transmitted by a CMTS in response to a received DCI-REQ.
+
+The DCI-RSP MUST be formatted as shown in Figure 8-42.
+
+![Diagram of Device class identification response (DCI-RSP) packet structure. The packet is 32 bits long, with bit positions 0, 8, 16, 24, and 31 marked. The top section is the MAC management message header. Below it, the first 8 bits (0-7) are the SID. The next 8 bits (8-15) are the first part of the Device class field, labeled 'Device class (cont.)'. The next 8 bits (16-23) are the Confirmation code. The remaining 8 bits (24-31) are the second part of the Device class field. The bottom section is the TLV encoded information.](1db1724d23ebada3bc4c8fc665159897_img.jpg)
+
+Bit 0 8 16 24 31
+
+MAC management message header
+
+SID Device class
+
+Device class (cont.) Confirmation code
+
+TLV encoded information
+
+J.122\_F8-42
+
+Diagram of Device class identification response (DCI-RSP) packet structure. The packet is 32 bits long, with bit positions 0, 8, 16, 24, and 31 marked. The top section is the MAC management message header. Below it, the first 8 bits (0-7) are the SID. The next 8 bits (8-15) are the first part of the Device class field, labeled 'Device class (cont.)'. The next 8 bits (16-23) are the Confirmation code. The remaining 8 bits (24-31) are the second part of the Device class field. The bottom section is the TLV encoded information.
+
+**Figure 8-42 – Device class identification response**
+
+Parameters MUST be as follows:
+
+- **SID:** The SID received in the associated DCI-REQ.
+- **Device class:** The device class field as received in the associated DCI-REQ.
+- **Confirmation code:** Refer to clause C.4.
+
+The CMTS MUST use only one of three confirmation codes in the DCI-RSP.
+
+- If the response is reject-temporary(3), the CM MUST reset its DCI-REQ retry counter to zero and MUST resend the DCI-REQ and wait for the DCI-RSP before proceeding.
+- If the response is reject-permanent(4), the CM MUST abort this registration attempt and MUST begin re-scanning for a different downstream channel. The CM MUST NOT retry this channel until it has tried all other DOCS downstream channels on the network.
+- If the response is success(0), the CM MUST continue with registration.
+
+The CMTS MUST retain the device class information for use in the DHCP process. The CMTS MUST create a DHCP agent option 82 tuple with the device class information and MUST insert this tuple in the DHCPDISCOVER from the corresponding CM before forwarding that DHCPDISCOVER to the DHCP server.
+
+### 8.3.25 Upstream transmitter disable (UP-DIS) MAC management message
+
+The UP-DIS message provides additional functionality to permanently or temporarily disable the modem, as well as to disable the modem for a specified period of time. It is used to control the admission of certain modem types and groups to the network as early as immediately before registration. It can also be used for network troubleshooting, disabling modems that violate network policies, or for avoiding request floods in a large network when the CMTS goes on-line.
+
+This message is stateless and can be issued by the CMTS at any time. The UP-DIS message is sent from a CMTS to a CM; there is no response from the CM transmitted back to the CMTS. UP-DIS messages may be unicast, in which case the destination address in the MAC header is the address of the selected CM; or multicast, in which case the destination address is a well-known MAC multicast address (see Annex A for details on well-known addresses).
+
+The CMTS MUST be capable of transmitting the UP-DIS message. The CMTS can transmit UP-DIS messages either as a result of a triggering event detected by the CMTS internally, or in response to a remote management command. Mechanisms for setting up, detecting and reporting situations where the transmission of an UP-DIS message might be appropriate are implementation-dependent. Similarly, signalling, which remotely instructs the CMTS to transmit a UP-DIS message, is outside the scope of this Recommendation. One of the possible implementations may be SNMP commands sent to the CMTS over the network.
+
+CMs SHOULD support the UP-DIS message in order to ease network management.
+
+Since the UP-DIS mechanism at the CM is stateless and the CMs do not retain disabled status after a power cycle, the CMTS MAY incorporate mechanisms to track disabled CMs by their MAC addresses. The CMTS would resend an UP-DIS message as appropriate to the modems that were permanently disabled by the network operator, and then power-cycled by the user in an attempt to re-register. However, the same function may also be implemented by the provisioning infrastructure on modem registration; therefore, if the CMTS is unable to track disabled modems autonomously, it SHOULD be able to send a UP-DIS in response to an external command.
+
+The UP-DIS message MUST be formatted as shown in Figure 8-43.
+
+![Diagram of UP-DIS message format showing a 32-bit structure. The top row indicates bit positions 0, 8, 16, 24, and 31. The first field is the MAC management message header. The second field is the UP-DIS timeout interval, which is a 32-bit unsigned integer. A note below the diagram reads J.122_F8-43.](86c74ee06f834f849f6cd094ca0b5867_img.jpg)
+
+|                                                          |   |    |    |    |
+|----------------------------------------------------------|---|----|----|----|
+| Bit 0                                                    | 8 | 16 | 24 | 31 |
+| MAC management message header                            |   |    |    |    |
+| UP-DIS timeout interval (0 = Off forever, FFFFFFFF = On) |   |    |    |    |
+
+J.122\_F8-43
+
+Diagram of UP-DIS message format showing a 32-bit structure. The top row indicates bit positions 0, 8, 16, 24, and 31. The first field is the MAC management message header. The second field is the UP-DIS timeout interval, which is a 32-bit unsigned integer. A note below the diagram reads J.122\_F8-43.
+
+**Figure 8-43 – UP-DIS message format**
+
+The only parameter is UP-DIS timeout interval, which MUST be encoded as follows.
+
+UP-DIS timeout interval is a 32-bit, unsigned integer representing the disable timeout interval in milliseconds. There are two special values defined:
+
+- 00000000 permanently disables the upstream of the modem, as described below.
+- FFFFFFFF remotely re-initializes the MAC, which resumes the normal operation of the modem.
+
+The CM MUST autonomously disable its upstream transmitter immediately upon receipt of an UP-DIS message with UP-DIS timeout interval = 0, regardless of any other transaction state (refer to clause 11), or the state of its control programme. The modem stops all transmissions, but continues to listen to the MAC messages sent in the downstream. Once disabled, the CM upstream transmitter MUST only be re-enabled by power cycling the CM, or by an UP-DIS message with UP-DIS timeout interval = FFFFFFFF. All other UP-DIS messages MUST be ignored when the upstream is disabled.
+
+If supported, the CM MUST autonomously reset its upstream transmitter upon receipt of an UP-DIS message with UP-DIS time-out interval = FFFFFFFF, regardless of any other transaction state (refer to clause 11), or the state of its control program. Resetting allows the modem to resume transmissions.
+
+Additional non-zero timeout values in the UP-DIS message SHOULD be supported. If supported, the CM MUST autonomously disable its upstream transmitter immediately upon receipt of an UP-DIS message with UP-DIS timeout interval  $T > 0$  for a period of  $T$  ms, regardless of any other transaction state (refer to clause 11), or the state of its control program. Although the timeout  $T$  is specified in ms, the CM MAY extend the specified timeout by up to 100 ms. When timeout expires, the CM SHOULD re-initialize the MAC as appropriate, starting with the initial ranging process and registration, because there is no guarantee that the CMTS has not de-registered it. In the disabled state, all other UP-DIS messages MUST be ignored, except for an UP-DIS message with UP-DIS timeout interval = FFFFFFFF or 00000000.
+
+### 8.3.26 Initial ranging request (INIT-RNG-REQ)
+
+A ranging request MUST be transmitted by a CM at initialization to determine network delay and request power adjustment. This message MUST use an FC\_TYPE = MAC-specific header and FC\_PARM = timing MAC header. This MUST be followed by a packet PDU in the format shown in Figure 8-44.
+
+![Diagram of a Packet PDU following the timing header. The diagram shows a 32-bit word structure. The top part is the 'MAC management message header', which is 16 bits long (bits 0 to 15). The bottom part is divided into three fields: 'SID' (bits 0 to 15), 'Downstream channel ID' (bits 16 to 23), and 'Upstream channel ID' (bits 24 to 31). The bit positions 0, 8, 16, 24, and 31 are marked at the top. There are break symbols on the left and right sides of the header section. The label 'J.122_F8-44' is in the bottom right corner.](f2a3faa7fc860dd26eda5b88460b0bcf_img.jpg)
+
+Diagram of a Packet PDU following the timing header. The diagram shows a 32-bit word structure. The top part is the 'MAC management message header', which is 16 bits long (bits 0 to 15). The bottom part is divided into three fields: 'SID' (bits 0 to 15), 'Downstream channel ID' (bits 16 to 23), and 'Upstream channel ID' (bits 24 to 31). The bit positions 0, 8, 16, 24, and 31 are marked at the top. There are break symbols on the left and right sides of the header section. The label 'J.122\_F8-44' is in the bottom right corner.
+
+**Figure 8-44 – Packet PDU following the timing header**
+
+The INIT-RNG-REQ differs from the RNG-REQ in that it is only transmitted in broadcast initial ranging opportunities and **MUST NOT** be transmitted on a logical upstream that is not a DOCS 2.0-only upstream. It also has an upstream channel ID in place of the pending till complete field in a RNG-REQ.
+
+Parameters **MUST** be as follows:
+
+- **SID:**
+  - Initialization SID if modem is attempting to join the network.
+  - Initialization SID if modem has not yet registered and is changing downstream, or both downstream and upstream channels, as directed by a downloaded parameter file.
+  - Primary SID (previously assigned in REG-RSP) if modem is registered and is changing upstream channels; if the CM is redoing initial ranging as a result of a DCC, UCC, or UCD change (see clauses 8.3.3 and 11.3.2); or if the CM is redoing initial ranging as a result of a temporary loss of downstream signal, while in S-CDMA mode (see clause 11.2.1).
+
+This is a 16-bit field of which the lower 14 bits define the SID with bits 14 and 15 defined to be 0.
+
+- **Downstream channel ID:** The identifier of the downstream channel on which the CM received the UCD which described this upstream. This is an 8-bit field.
+- **Upstream channel ID:** The upstream channel ID from the UCD the CM is using to transmit this INIT-RNG-REQ. In the case where multiple logical upstreams are sharing the same spectrum, and the broadcast initial ranging opportunities of some of these logical channels are aligned, this allows the CMTS to know which logical channel the CM is using.
+
+A CM **MUST** set the RSVD field of the MAC management message header to report support of the S-CDMA maximum scheduled codes if, and only if, the CMTS indicated that it supports the S-CDMA maximum scheduled codes from TLV-17 of the UCD for the upstream channel on which the CM is ranging. In this case, the CM **MUST** report the maximum ratio of number of active codes to maximum scheduled codes that the CM can support; this ratio is indicated by a bit mask in the reserved field as shown below. For example, if the number of active codes on the channel is 128 and the CM supports a minimum of 64 scheduled codes (the minimum number of allowed active codes), the CM would report a ratio of 2. The CMTS will use this value in calculating an appropriate value for maximum scheduled codes to assign to the CM. The CM **SHOULD** support a maximum ratio of 32.
+
+When the CM reports support for the S-CDMA maximum scheduled codes, the CM **MUST** also report its current transmit power shortfall (in dB). The CM power shortfall is the difference between the current target transmit power of the ranging request and the maximum S-CDMA spreader-on transmit power of 53 dBmV. The CM **MUST** report a power shortfall of 0 if the current target
+
+transmit power of the ranging request is less than or equal to 53 dBmV. This value will be used by the CMTS for calculating appropriate values for S-CDMA maximum scheduled codes and S-CDMA power headroom for the CM.
+
+The format of the RSVD field is:
+
+|                                                    |                                                                                          |                                          |
+|----------------------------------------------------|------------------------------------------------------------------------------------------|------------------------------------------|
+| Bit 7: 1= S-CDMA maximum scheduled codes supported | Bits 6 to 5: CM maximum ratio of:<br><Anchor6><br>00 = 2<br>01 = 8<br>10 = 16<br>11 = 32 | Bits 4 to 0: CM power shortfall (1/4 dB) |
+|----------------------------------------------------|------------------------------------------------------------------------------------------|------------------------------------------|
+
+### 8.3.27 Test request (TST-REQ)
+
+The test request is used to force a CM to enter or leave one of two test modes. The TST-REQ message with Mode!= 0 MUST NOT be sent by the CMTS except in response to an explicit command from the operator.
+
+![Diagram of the Test request (TST-REQ) message structure. It shows a 32-bit word with bit positions 0, 8, 16, 24, and 31. The first 16 bits (bits 0-15) are the MAC management message header. The next 8 bits (bits 16-23) are the Mode field. The final 8 bits (bits 24-31) are TLV encoded information for the channel.](a9042d8edc99d26ea117a7d56e171d8e_img.jpg)
+
+|     |                               |   |                                            |    |    |
+|-----|-------------------------------|---|--------------------------------------------|----|----|
+| Bit | 0                             | 8 | 16                                         | 24 | 31 |
+|     | MAC management message header |   |                                            |    |    |
+|     | Mode                          |   | TLV encoded<br>information for the channel |    |    |
+
+Diagram of the Test request (TST-REQ) message structure. It shows a 32-bit word with bit positions 0, 8, 16, 24, and 31. The first 16 bits (bits 0-15) are the MAC management message header. The next 8 bits (bits 16-23) are the Mode field. The final 8 bits (bits 24-31) are TLV encoded information for the channel.
+
+Figure 8-45 – Test request
+
+Parameters MUST be as follows:
+
+- **Mode:**
+  - 0 = Disable all test modes and reboot.
+  - 1 = Transmit a continuous (non-bursted) upstream signal at the commanded modulation rate, carrier frequency and power level. The chip sequence at the spreader output is replaced with an alternating binary sequence (1, -1, 1, -1, 1, -1, ...) at nominal amplitude, equal on I and Q. The CM tracks the downstream symbol clock and uses it to generate the upstream symbol clock as in normal synchronous operation.
+  - 2 = Transmit a continuous (non-bursted), unmodulated (CW) upstream signal at the commanded carrier frequency, modulation rate and power level. This is equivalent to replacing the chip sequence at the spreader output with the constant sequence (1, 1, 1, 1, 1, 1, ...) at nominal amplitude, equal on both I and Q. The CM tracks the downstream symbol clock and uses it to generate the upstream symbol clock as in normal synchronous operation.
+
+In normal operation, the CM MUST ignore any TST-REQ message it receives subsequent to receiving the first SYNC message. Note that this makes it less convenient to use this test mode with a CMTS, since the CMTS may send a SYNC message before the CM sees a TST-REQ message.
+
+After acquiring a downstream signal, and prior to receiving a SYNC message, if the CM receives a TST-REQ message (either unicast to the CM itself, or broadcast) with Mode  $\neq 0$ , the CM MUST begin the test mode indicated in the mode parameter, using the channel parameters included in the TST-REQ message.
+
+In test mode, if the CM receives a TST-REQ message (either unicast to the CM itself, or broadcast) with Mode = 0, the CM MUST reboot. The CM MUST reboot after the expiration of the T16 timer, a 30 minute test mode timer.
+
+The TST-REQ message MUST be generated in the format shown in Figure 8-45, including all of the parameters coded as TLV-tuples defined in Table 8-22.
+
+**Table 8-22 – Channel TLV parameters**
+
+| Name                            | Type<br>(1 byte) | Length<br>(1 byte) | Value<br>(variable length)                                                                                                                                                                                                                         |
+|---------------------------------|------------------|--------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Modulation rate                 | 1                | 1                  | Multiples of base rate of 160 kHz (value is 1, 2, 4, 8, 16 or 32).<br>This TLV MUST be present if the test mode is 1.                                                                                                                              |
+| Frequency                       | 2                | 4                  | Upstream carrier frequency (Hz).<br>This TLV MUST be present if the test mode is 1 or 2.                                                                                                                                                           |
+| Power                           | 3                | 1                  | This TLV specifies the power (unsigned 8-bit, dBmV units) at which the CM MUST transmit the TST-REQ message.<br>This TLV MUST be present if the test mode is 1 or 2.                                                                               |
+| S-CDMA US ratio numerator 'M'   | 4                | 2                  | The numerator (M) of the M/N ratio relating the downstream symbol clock to the upstream modulation clock.<br>This TLV MUST be present if the test mode is 1.<br>This TLV MUST be present if the test mode is 2 and the operation is synchronous.   |
+| S-CDMA US ratio denominator 'N' | 5                | 2                  | The denominator (N) of the M/N ratio relating the downstream symbol clock to the upstream modulation clock.<br>This TLV MUST be present if the test mode is 1.<br>This TLV MUST be present if the test mode is 2 and the operation is synchronous. |
+
+## 9 Media access control protocol operation
+
+### 9.1 Upstream bandwidth allocation
+
+The upstream channel is modelled as a stream of mini-slots. The CMTS MUST generate the time reference for identifying these slots. It MUST also control access to these slots by the cable modems. For example, it MAY grant some number of contiguous slots to a CM for it to transmit a data PDU. The CM MUST time its transmission so that the CMTS receives it in the time reference specified. This clause describes the elements of protocol used in requesting, granting and using upstream bandwidth. The basic mechanism for assigning bandwidth management is the allocation MAP. Please refer to Figure 9-1.
+
+![Diagram of the Allocation MAP structure. At the top, a 'Map PDU' box is shown being transmitted on the downstream channel by the CMTS. Lines from this box point to a horizontal timeline below labeled 'Permitted use of the upstream channel'. This timeline is divided into segments. Below this, a more detailed view shows 'Mini-slots' indicated by a horizontal arrow. These mini-slots are allocated for different purposes: 'CM Tx opportunity' (rounded rectangles), 'Request contention area' (rectangle), another 'CM Tx opportunity', and 'Maintenance' (hexagon). The diagram also indicates 'Previous map', 'Current map', and 'As-yet unmapped time' along the bottom timeline.](5c690861d263afceef4f7ab56ab13264_img.jpg)
+
+The diagram illustrates the Allocation MAP structure. At the top, a 'Map PDU' is shown being transmitted on the downstream channel by the CMTS. Below this, a horizontal bar represents the 'Permitted use of the upstream channel', divided into several segments. A callout from the Map PDU points to this bar. Below the bar, a sequence of 'Mini-slots' is shown, indicated by a horizontal arrow. The mini-slots are grouped into three main categories: 'CM Tx opportunity', 'Request contention area', and 'Maintenance'. The 'CM Tx opportunity' segments are shown as rounded rectangles, the 'Request contention area' as a rectangle, and the 'Maintenance' segment as a hexagon. The diagram also shows the transition from 'Previous map' to 'Current map' and 'As-yet unmapped time'.
+
+Diagram of the Allocation MAP structure. At the top, a 'Map PDU' box is shown being transmitted on the downstream channel by the CMTS. Lines from this box point to a horizontal timeline below labeled 'Permitted use of the upstream channel'. This timeline is divided into segments. Below this, a more detailed view shows 'Mini-slots' indicated by a horizontal arrow. These mini-slots are allocated for different purposes: 'CM Tx opportunity' (rounded rectangles), 'Request contention area' (rectangle), another 'CM Tx opportunity', and 'Maintenance' (hexagon). The diagram also indicates 'Previous map', 'Current map', and 'As-yet unmapped time' along the bottom timeline.
+
+J.122\_F9-1
+
+**Figure 9-1 – Allocation MAP**
+
+The allocation MAP is a MAC management message transmitted by the CMTS on the downstream channel which describes, for some interval, the uses to which the upstream mini-slots MUST be put. A given MAP MAY describe some slots as grants for particular stations to transmit data in, other slots as available for contention transmission, and other slots as an opportunity for new stations to join the link.
+
+Many different scheduling algorithms MAY be implemented in the CMTS by different vendors; this Recommendation does not mandate a particular algorithm. Instead, it describes the protocol elements by which bandwidth is requested and granted.
+
+The bandwidth allocation includes the following basic elements:
+
+- Each CM has one or more short (14-bit) service identifiers (SIDs) as well as a 48-bit address.
+- Upstream bandwidth is divided into a stream of mini-slots. Each mini-slot is numbered relative to a master reference maintained by the CMTS. The master reference is distributed to the CMs by means of SYNC and UCD packets (see clause 6.2.11.2).
+- CMs may issue requests to the CMTS for upstream bandwidth.
+
+The CMTS MUST transmit allocation MAP PDUs on the downstream channel defining the allowed usage of each mini-slot. The MAP is described below.
+
+### 9.1.1 The allocation MAP MAC management message
+
+The allocation MAP is a varying-length MAC management message that is transmitted by the CMTS to define transmission opportunities on the upstream channel. It includes a fixed-length
+
+header followed by a variable number of information elements (IEs) in the format shown in clause 8.3.4. Each information element defines the allowed usage for a range of mini-slots.
+
+NOTE – For TDMA channels, it should be understood by both CM and CMTS that the lower (26-M) bits of alloc start and ack times MUST be used as the effective MAP start and ack times, where M is defined in clause 8.3.3. The relationship between alloc start/ack time counters and the timestamp counter is further described in clause 9.3.4. For DOCS 2.0 S-CDMA channels, the alloc start/ack time counters are defined in mini-slots that are related to the timestamp counter, frame counter and S-CDMA timestamp snapshot as described in clause 6.2.11.2.
+
+### 9.1.2 Information elements
+
+Each IE consists of a 14-bit service ID, a 4-bit type code, and a 14-bit starting offset as defined in clause 8.3.4. Since all stations MUST scan all IEs, it is critical that IEs be short and relatively fixed format. IEs within the MAP are strictly ordered by starting offset. For most purposes, the duration described by the IE is inferred by the difference between the IE's starting offset and that of the following IE. For this reason, a null IE MUST terminate the list. Refer to Table 8-20.
+
+Five types of service IDs are defined:
+
+- 1) 0x3FFF – Broadcast; intended for all stations.
+- 2) 0x3E00-0x3FFE – Multicast; purpose is defined administratively. Refer to Annex A.
+- 3) 0x2000-0x3DFF – Expanded unicast; intended for a particular CM or a particular service within that CM, when supported by both the CM and CMTS.
+- 4) 0x0001-0x1FFF – Unicast; intended for a particular CM or a particular service within that CM.
+- 5) 0x0000 – Null address; addressed to no station.
+
+A CM MUST support the expanded unicast SID space. A CMTS MAY support the expanded unicast SID space.
+
+Unicast SIDs (including expanded unicast SIDs) MUST be unique on a given logical upstream. The CMTS MAY support unicast SIDs assignments which overlap across multiple logical upstreams within a single MAC-sublayer domain.
+
+All of the information elements defined below MUST be supported by conformant CMs. Conforming CMTSs MAY use any of these information elements when creating bandwidth allocation MAPs.
+
+#### 9.1.2.1 The request IE
+
+The request IE provides an upstream interval in which requests MAY be made for bandwidth for upstream data transmission. The character of this IE changes depending on the class-of-service ID. If broadcast, this is an invitation for CMs to contend for requests. Clause 9.4 describes which contention transmit opportunity may be used. If unicast, this is an invitation for a particular CM to request bandwidth. Unicasts MAY be used as part of a quality of service scheduling scheme (refer to clause 10.2). Packets transmitted in this interval MUST use the request MAC frame format (refer to clause 8.2.5.3).
+
+A small number of priority request SIDs are defined in clause A.2.3. These allow contention for request IEs to be limited to service flows of a given traffic priority (refer to clause C.2.2.5.1).
+
+#### 9.1.2.2 The request/data IE
+
+The request/data IE provides an upstream interval in which requests for bandwidth or short data packets MAY be transmitted. This IE is distinguished from the request IE in that:
+
+- It provides a means by which allocation algorithms MAY provide for "immediate" data contention under light loads, and a means by which this opportunity can be withdrawn as network loading increases.
+
+- Multicast service IDs MUST be used to specify maximum data length, as well as allowed random starting points within the interval. For example, a particular multicast ID may specify a maximum of 64-byte data packets, with transmit opportunities every fourth slot.
+
+A small number of well-known multicast Service IDs are defined in Annex A. Others are available for vendor-specific algorithms.
+
+Since data packets transmitted within this interval may collide, the CMTS MUST acknowledge any that are successfully received. The data packet MUST indicate in the MAC header that a data acknowledgment is desired (see Table 8-13).
+
+#### **9.1.2.3 The initial maintenance IE**
+
+The initial maintenance IE, when used with the broadcast SID, provides an interval in which new stations may join the network. A long interval, equivalent to the maximum round-trip propagation delay plus the transmission time of a ranging request (RNG-REQ) message (see clause 9.3.3), MUST be provided to allow new stations to perform initial ranging. Packets transmitted in this interval MUST use the RNG-REQ or the INIT-RNG-REQ MAC management message format (refer to clauses 8.3.5 and 8.3.26).
+
+On DOCS 2.0-only upstream channels, the initial maintenance IE MAY be used with a unicast SID. This is done to provide unicast initial maintenance opportunities in place of station maintenance opportunities at the discretion of the CMTS. This may be useful if the first unicast ranging opportunity on an S-CDMA channel needs to have spreader-off just like initial maintenance, but it is not desirable to impose the overhead of having the spreader-off on routine station maintenance. Unicast initial maintenance opportunities only need to be large enough to allow transmission of the ranging request. The CMTS MUST NOT provide unicast initial maintenance opportunities on any logical upstream which is not a DOCS 2.0-only upstream.
+
+#### **9.1.2.4 The station maintenance IE**
+
+The station maintenance IE provides an interval in which stations are expected to perform some aspect of routine network maintenance, such as ranging or power adjustment. The CMTS MAY request that a particular CM perform some task related to network maintenance, such as periodic transmit power adjustment. In this case, the station maintenance IE is unicast to provide upstream bandwidth in which to perform this task. Packets transmitted in this interval MUST use the RNG-REQ MAC management message format (see clause 8.3.5).
+
+#### **9.1.2.5 Short and long data grant IEs**
+
+The short and long data grant IEs provide an opportunity for a CM to transmit one or more upstream PDUs. These IEs are issued either in response to a request from a station, or because of an administrative policy providing some amount of bandwidth to a particular station (see class-of-service discussion below). These IEs MAY also be used with an inferred length of zero mini-slots (a zero length grant), to indicate that a request has been received and is pending (a data grant pending).
+
+Short data grants are used with intervals less than or equal to the maximum burst size for this usage specified in the upstream channel descriptor. If short data burst profiles are defined in the UCD, then all long data grants MUST be for a larger number of mini-slots than the maximum for short data. The distinction between long and short data grants may be exploited in physical-layer forward-error-correction coding; otherwise, it is not meaningful to the bandwidth allocation process.
+
+If this IE is a data grant pending (a zero length grant), it MUST follow the null IE. This allows cable modems to process all actual allocations first, before scanning the MAP for data grants pending and data acknowledgments.
+
+#### **9.1.2.6 Data acknowledge IE**
+
+The data acknowledge IE acknowledges that a data PDU was received. The CM MUST have requested this acknowledgment within the data PDU (normally this would be done for PDUs transmitted within a contention interval in order to detect collisions).
+
+This IE MUST follow the null IE. This allows cable modems to process all actual interval allocations first, before scanning the MAP for data grants pending and data acknowledgments.
+
+#### **9.1.2.7 Expansion IE**
+
+The expansion IE provides for extensibility, if more than 16 code points or 32 bits are needed for future IEs.
+
+#### **9.1.2.8 Null IE**
+
+A null IE terminates all actual allocations in the IE list. It is used to infer a length for the last interval. All data acknowledge IEs and all data grant pending IEs (data grants with an inferred length of 0) must follow the null IE.
+
+#### **9.1.2.9 Advanced PHY short and long data grant IEs**
+
+These IEs are the advanced PHY channel equivalent of the short and long data grant IEs in clause 9.1.2.5. In addition, these IEs allow DOCS 2.0 modems operating in DOCS 2.0 TDMA mode to share the same upstream channel with DOCS 1.x modems. Modems registered in DOCS 1.x mode MUST NOT use these intervals.
+
+For upstream channels supporting a mixture of DOCS 1.x and DOCS 2.0 TDMA CMs, the CMTS MUST use the SID in the request and the operational state of the CM to distinguish between requests for IUC 5 and 6 data grants and requests for IUC 9 and 10 data grants (refer to clause 11.2.9 for additional information). Once this distinction has been made, the CMTS then uses the request size to distinguish between a long grant and a short grant.
+
+Once a CMTS has received a REG\_ACK from a 2.0 CM on a type 2 channel, the CMTS MUST NOT send data grants using IUCs 5 or 6 if either IUC 9 or 10 is defined for that upstream channel. This restriction allows the CM to support only 7 burst profiles simultaneously.
+
+#### **9.1.2.10 Advanced PHY unsolicited grant IE**
+
+This IE can be used by the CMTS to make unsolicited grants of bandwidth to DOCS 2.0 CMs. If a significant portion of the traffic for an upstream is going to consist of unsolicited grants of a particular size, this IE provides a way for the CMTS to provide a set of physical layer parameters (such as code word length and FEC length) well tailored to that traffic, without compromising the general usefulness of the advanced phy short or advanced phy long data grant IEs. It is never used by the CM to calculate the size of a bandwidth request. The CMTS MUST NOT use it to make grants to DOCS 1.x CMs.
+
+### **9.1.3 Requests**
+
+Requests refer to the mechanism that CMs use to indicate to the CMTS that it needs upstream bandwidth allocation. A Request MAY come as a stand-alone request frame transmission (refer to clause 8.2.5.3) or it MAY come as a piggyback request in the EHDR of another frame transmission (refer to clause 8.2.6).
+
+The request frame MAY be transmitted during any of the following intervals:
+
+- request IE;
+- request/data IE;
+- short data grant IE;
+- long data grant IE;
+
+- adv PHY short data grant IE;
+- adv PHY long data grant IE;
+- adv PHY unsolicited grant IE.
+
+A piggyback request MAY be contained in the following extended headers:
+
+- request EH element;
+- upstream privacy EH element;
+- upstream privacy EH element with fragmentation.
+
+The request MUST include:
+
+- the service ID making the request;
+- the number of mini-slots requested.
+
+The CM MUST request the number of mini-slots needed to transmit an entire frame, or a fragment containing the entire remaining portion of a frame that a previous grant has caused to be fragmented. The frame may be a single MAC frame, or a MAC frame that has been formed by the concatenation of multiple MAC frames (see clause 8.2.5.5). The request from the CM MUST be large enough to accommodate the entire necessary physical layer overhead (see clause 6.2) for transmitting the MAC frame or fragment. The CM MUST NOT make a request that would violate the limits on data grant sizes in the UCD message (see clause 8.3.3) or any limits established by QoS parameters associated with the service flow.
+
+The CM MUST NOT request more mini-slots than are necessary to transmit the MAC frame. This means that if the CM is using short and long data IUCs to transmit data and the frame can fit into a short data grant, the CM MUST use the short data grant IUC attributes to calculate the amount of bandwidth to request and MUST make a request less than or equal to the short data maximum burst size. If the CM is using advanced PHY short and long data IUCs to transmit data and the frame can fit into an advanced PHY short data grant, the CM MUST use the advanced PHY short data grant IUC attributes to calculate the amount of bandwidth to request and MUST make a request less than or equal to the advanced PHY short data maximum burst size.
+
+The CM MUST have only one request outstanding at a time per service ID. If the CMTS does not immediately respond with a data grant, the CM is able to unambiguously determine that its request is still pending because the CMTS MUST continue to issue a data grant pending in every MAP that has an ack time indicating the request has already been processed until the request is granted or discarded.
+
+In MAPs, the CMTS MUST NOT make a data grant greater than 255 mini-slots to any assigned service ID. This puts an upper bound on the grant size the CM has to support.
+
+#### 9.1.4 Information element feature usage summary
+
+Table 9-1 summarizes what types of frames the CM can transmit using each of the MAP IE types that represent transmit opportunities. A "MUST" entry in the table means that, if appropriate, a compliant CM implementation has to be able to transmit that type of frame in that type of opportunity. A "MAY" entry means that compliant CM implementation does not have to be able to transmit that type of frame in that type of opportunity but that it is legal for it to do so, if appropriate. A "MUST NOT" entry means that a compliant CM will never transmit that type of frame in that type of opportunity.
+
+**Table 9-1 – IE feature compatibility summary**
+
+| Information element          | Transmit request frame | Transmit concatenated MAC frame | Transmit fragmented MAC frame | Transmit RNG-REQ | Transmit any other MAC frame |
+|------------------------------|------------------------|---------------------------------|-------------------------------|------------------|------------------------------|
+| Request IE                   | MUST                   | MUST NOT                        | MUST NOT                      | MUST NOT         | MUST NOT                     |
+| Request/data IE              | MUST                   | MAY                             | MUST NOT                      | MUST NOT         | MAY                          |
+| Initial maintenance IE       | MUST NOT               | MUST NOT                        | MUST NOT                      | MUST             | MUST NOT                     |
+| Station maintenance IE       | MUST NOT               | MUST NOT                        | MUST NOT                      | MUST             | MUST NOT                     |
+| Short data grant IE          | MAY                    | MUST                            | MUST                          | MUST NOT         | MUST                         |
+| Long data grant IE           | MAY                    | MUST                            | MUST                          | MUST NOT         | MUST                         |
+| Adv PHY short data grant IE  | MAY                    | MUST                            | MUST                          | MUST NOT         | MUST                         |
+| Adv PHY long data grant IE   | MAY                    | MUST                            | MUST                          | MUST NOT         | MUST                         |
+| Adv PHY unsolicited grant IE | MAY                    | MUST                            | MUST                          | MUST NOT         | MUST                         |
+
+### 9.1.5 MAP transmission and timing
+
+The allocation MAP MUST be transmitted in time to propagate across the physical cable and be received and handled by the receiving CMs. As such, it MAY be transmitted considerably earlier than its effective time. The components of the delay are:
+
+- worst-case round-trip propagation delay – may be network-specific, but on the order of hundreds of microseconds;
+- queuing delays within the CMTS – implementation-specific;
+- processing delays within the CMs – MUST allow a minimum processing time by each CM as specified in Annex B (CM MAP processing time), which has to include any upstream delays caused by the DOCS 2.0 TDMA;
+- downstream delays caused by the PMD-layer framer and the FEC interleaver.
+
+Within these constraints, vendors may wish to minimize this delay so as to minimize latency of access to the upstream channel.
+
+The number of mini-slots described MAY vary from MAP to MAP. At minimum, a MAP MAY describe a single mini-slot. This would be wasteful in both downstream bandwidth and in processing time within the CMs. At maximum, a MAP MAY stretch to tens of milliseconds. Such a MAP would provide poor upstream latency. Allocation algorithms MAY vary the size of the maps over time to provide a balance of network utilization and latency under varying traffic loads.
+
+At minimum, a MAP MUST contain two information elements: one to describe an interval, and a null IE to terminate the list. At a maximum, a MAP MUST be bounded by a limit of 240 information elements. Maps are also bounded in that they MUST NOT describe more than 4096 mini-slots into the future. The latter limit is intended to bound the number of future mini-slots that each CM is required to track. A CM MUST be able to support multiple outstanding MAPs. Even though multiple MAPs may be outstanding, the sum of the number of mini-slots they describe MUST NOT exceed 4096.
+
+The set of all MAPs, taken together, MUST describe every mini-slot in the upstream channel. If a CM fails to receive a MAP describing a particular interval, it MUST NOT transmit during that interval.
+
+### 9.1.6 Protocol example
+
+This clause illustrates the interchange between the CM and the CMTS when the CM has data to transmit (Figure 9-2). Suppose a given CM has a data PDU available for transmission.
+
+![Figure 9-2 – Protocol example. A sequence diagram showing the interaction between a CMTS and a CM. The CMTS transmits a MAP PDU at t1, which the CM receives at t2. The MAP PDU contains a request IE starting at t3. The CM calculates a random offset t6 and transmits a Request at t4, which arrives at the CMTS at t6. The CMTS receives the request and schedules it for service in the next MAP. The CMTS transmits a second MAP PDU at t7, which the CM receives at t8. This MAP PDU contains a data grant starting at t9. The CM transmits its Data PDU at t10, which arrives at the CMTS at t11. Above the timeline, a box labeled 'Slots mapped by first MAP PDU' spans from t3 to t9, and a box labeled 'Second MAP' spans from t9 to t11. The diagram is labeled J.122_F9-2.](b43ec8e53bbe827c4572d9fd80ebc21a_img.jpg)
+
+```
+
+sequenceDiagram
+    participant CMTS
+    participant CM
+    Note over CMTS, CM: t1
+    CMTS->>CM: MAP PDU
+    Note over CMTS, CM: t2
+    Note over CMTS, CM: t3 (Effective start time)
+    Note over CMTS, CM: t4
+    CM->>CMTS: Request
+    Note over CMTS, CM: t5 (Request IE start)
+    Note over CMTS, CM: t6 (Request arrival)
+    Note over CMTS, CM: t7
+    CMTS->>CM: MAP PDU
+    Note over CMTS, CM: t8
+    Note over CMTS, CM: t9 (Effective start time)
+    Note over CMTS, CM: t10
+    CM->>CMTS: Data PDU
+    Note over CMTS, CM: t11 (Data grant start/arrival)
+
+```
+
+Figure 9-2 – Protocol example. A sequence diagram showing the interaction between a CMTS and a CM. The CMTS transmits a MAP PDU at t1, which the CM receives at t2. The MAP PDU contains a request IE starting at t3. The CM calculates a random offset t6 and transmits a Request at t4, which arrives at the CMTS at t6. The CMTS receives the request and schedules it for service in the next MAP. The CMTS transmits a second MAP PDU at t7, which the CM receives at t8. This MAP PDU contains a data grant starting at t9. The CM transmits its Data PDU at t10, which arrives at the CMTS at t11. Above the timeline, a box labeled 'Slots mapped by first MAP PDU' spans from t3 to t9, and a box labeled 'Second MAP' spans from t9 to t11. The diagram is labeled J.122\_F9-2.
+
+**Figure 9-2 – Protocol example**
+
+Description:
+
+- 1) At time  $t_1$ , the CMTS transmits a MAP whose effective starting time is  $t_3$ . Within this MAP is a request IE which will start at  $t_5$ . The difference between  $t_1$  and  $t_3$  is needed to allow for all the delays discussed in clause 9.1.5.
+- 2) At  $t_2$ , the CM receives this MAP and scans it for request opportunities. In order to minimize request collisions, it calculates  $t_6$  as a random offset based on the data backoff start value in the most recent MAP (see clause 9.4; also, the multicast SID definitions in clause A.2).
+- 3) At  $t_4$ , the CM transmits a request for as many mini-slots as needed to accommodate the PDU. Time  $t_4$  is chosen based on the ranging offset (see clause 9.3.3) so that the request will arrive at the CMTS at  $t_6$ .
+- 4) At  $t_6$ , the CMTS receives the request and schedules it for service in the next MAP (the choice of which requests to grant will vary with the class of service requested, any competing requests, and the algorithm used by the CMTS).
+- 5) At  $t_7$ , the CMTS transmits a MAP whose effective starting time is  $t_9$ . Within this MAP, a data grant for the CM will start at  $t_{11}$ .
+- 6) At  $t_8$ , the CM receives the MAP and scans for its data grant.
+- 7) At  $t_{10}$ , the CM transmits its data PDU so that it will arrive at the CMTS at  $t_{11}$ . Time  $t_{10}$  is calculated from the ranging offset as in step 3.
+
+Steps 1 and 2 need not contribute to access latency if CMs routinely maintain a list of request opportunities.
+
+At Step 3, the request may collide with requests from other CMs and be lost. The CMTS does not directly detect the collision. The CM determines that a collision (or other reception failure) occurred when the next MAP with an ack time indicating that the request would have been received and processed fails to include an acknowledgment of the request. The CM MUST then perform a back-off algorithm and retry (refer to clause 9.4.1).
+
+At Step 4, the CMTS scheduler MAY fail to accommodate the request within the next MAP. If so, it MUST reply with a zero-length grant in that MAP or discard the request by giving no grant at all. It MUST continue to report this zero-length grant in all succeeding maps until the request can be granted or is discarded. This MUST signal to the CM that the request is still pending. So long as the CM is receiving a zero-length grant, it MUST NOT issue new requests for that service queue.
+
+### 9.1.7 MAP generation example – Two logical upstreams
+
+This clause illustrates the timing requirements for scheduling an S-CDMA and a TDMA logical channel on the same physical channel (Figure 9-3).
+
+For simplicity, it is assumed that:
+
+- the duration of the S-CDMA frames is an integral multiple of the duration of the TDMA mini-slots;
+- both TDMA and S-CDMA maps begin and end on frame boundaries;
+- for the duration of the example, there are no S-CDMA bursts with the spreader-off, and there are no broadcast initial ranging regions where both channels are active.
+
+![Figure 9-3 – Logical S-CDMA TDMA channels. A timing diagram showing the relationship between S-CDMA and TDMA logical channels over time. The bottom axis represents TDMA mini-slots, with vertical dashed lines indicating frame boundaries. Above this, the CM TDMA logical channel is shown with grants (white boxes) and null grants (shaded boxes labeled 'Null SID'). The top axis shows the S-CDMA logical channel with S-CDMA frames (stacks of horizontal lines). Arrows T1 through T8 indicate key time points: T1 and T2 at the start, T3 and T7 marking the start and end of an S-CDMA map, and T4 and T8 marking the start and end of a TDMA map. A legend at the bottom left defines the symbols for frame boundaries, mini-slot counts, null grants, S-CDMA frames, and TDMA grants.](0b8f0df92a831a94cdac664d8b05f0ec_img.jpg)
+
+The diagram shows two logical channels: S-CDMA and CM TDMA. The S-CDMA channel has frames represented by stacked horizontal lines. The TDMA channel has mini-slots and grants. Key time points are marked:  $T_1$  and  $T_2$  are transmission times for maps.  $T_3$  to  $T_7$  is the S-CDMA map duration.  $T_4$  to  $T_8$  is the TDMA map duration. During the S-CDMA active period, the TDMA channel has 'Null SID' grants to prevent interference. A legend defines: vertical dashed lines as Frame boundaries, a horizontal line with ticks as Mini-slot count, a shaded box as Null grant (Null SID), a stack of lines as S-CDMA frame, and an empty box as TDMA grant.
+
+Figure 9-3 – Logical S-CDMA TDMA channels. A timing diagram showing the relationship between S-CDMA and TDMA logical channels over time. The bottom axis represents TDMA mini-slots, with vertical dashed lines indicating frame boundaries. Above this, the CM TDMA logical channel is shown with grants (white boxes) and null grants (shaded boxes labeled 'Null SID'). The top axis shows the S-CDMA logical channel with S-CDMA frames (stacks of horizontal lines). Arrows T1 through T8 indicate key time points: T1 and T2 at the start, T3 and T7 marking the start and end of an S-CDMA map, and T4 and T8 marking the start and end of a TDMA map. A legend at the bottom left defines the symbols for frame boundaries, mini-slot counts, null grants, S-CDMA frames, and TDMA grants.
+
+J.122\_F9-3
+
+Figure 9-3 – Logical S-CDMA TDMA channels
+
+Description:
+
+- The example begins at  $T_1$  and the first MAP discussed takes effect at  $T_3$ .
+- At time  $T_1$ , the CMTS transmits a S-CDMA map whose effective starting time is  $T_3$  and end time is  $T_7$ .
+- At time  $T_2$ , the CMTS transmits a TDMA map whose effective starting time is  $T_4$  and end time is  $T_8$ .
+- At time  $T_3$  the S-CDMA map has three frames of S-CDMA grants. The CMTS upstream scheduler must not allow TDMA transmissions to occur at the same time. To prevent the two channels from interfering with each other, the scheduler will mute the TDMA upstream (by granting mini-slots to the null SID for the TDMA channel) during the time S-CDMA is active.
+- At time  $T_4$ , on a frame boundary, the TDMA channel becomes active. In this example, it has one empty mini-slot (null SID) to guarantee sufficient guard time for the following
+
+TDMA burst. Then it proceeds with usable TDMA grants. At the same time, the S-CDMA upstream is muted by granting mini-slots to the null SID in every frame.
+
+- 6) At  $T_5$  and  $T_6$ , the TDMA logical channel and S-CDMA logical channel transmit the next map for the upstream. Note that Figure 9-3 does not continue to detail the complete maps beginning at  $T_7$  and  $T_8$ .
+- 7) At time  $T_7$ , the S-CDMA map sends a group of S-CDMA grants in a frame. Note that when switching from TDMA to S-CDMA, there is no requirement for additional guard time.
+
+## 9.2 Support for multiple channels
+
+Vendors may choose to offer various combinations of upstream and downstream channels within one MAC service access point. The upstream bandwidth allocation protocol allows for multiple upstream channels to be managed via one or many downstream channels. Some or all of these multiple upstream channels may even co-exist on the same upstream transmit centre frequency.
+
+If multiple upstream channels are associated with a single downstream channel, then the CMTS MUST send one allocation MAP per upstream channel. The MAP's channel identifier, taken with the upstream channel descriptor message (see clause 8.3.3), MUST specify to which channel each MAP applies. There is no requirement that the maps be synchronized across channels. Appendix III provides an example.
+
+If multiple logical upstream channels are associated with the same upstream centre frequency on the same cable segment, then the CMTS MUST ensure that the MAP allocations to each logical upstream channel sharing the same spectrum do not coincide with the potential transmit opportunities of the other logical upstream channels with the possible exception of broadcast initial ranging opportunities. When sharing the upstream between S-CDMA and TDMA channels, the CMTS MUST take into account the lack of guard time on the synchronous physical layer upstreams. Annex G provides more information on the co-existence of DOCS 1.x and DOCS 2.0 channels.
+
+If multiple downstream channels are associated with a single upstream channel, the CMTS MUST ensure that the allocation MAP reaches all CMs. That is, if some CMs are attached to a particular downstream channel, then the MAP MUST be transmitted on that channel. This may necessitate that multiple copies of the same MAP be transmitted. The alloc start time in the MAP header MUST always relate to the timebase reference on the downstream channel on which it is transmitted.
+
+If multiple downstream channels are associated with multiple upstream channels, the CMTS may need to transmit multiple copies of multiple maps to ensure both that all upstream channels are mapped and that all CMs have received their needed maps.
+
+## 9.3 Timing and synchronization
+
+One of the major challenges in designing a MAC protocol for a cable network is compensating for the large delays involved. These delays are an order of magnitude larger than the transmission burst time in the upstream. To compensate for these delays, the cable modem MUST be able to time its transmissions precisely to arrive at the CMTS at the start of the assigned mini-slot.
+
+To accomplish this, two pieces of information are needed by each cable modem:
+
+- a global timing reference sent downstream from the CMTS to all cable modems;
+- a timing offset, calculated during a ranging process, for each cable modem.
+
+### 9.3.1 Global timing reference
+
+For TDMA channels, the CMTS MUST create a global timing reference by transmitting the time synchronization (SYNC) MAC management message downstream at a nominal frequency. The
+
+message contains a timestamp that exactly identifies when the CMTS transmitted the message. Cable modems MUST then compare the actual time the message was received with the timestamp and adjust their local clock references accordingly.
+
+For S-CDMA channels, the CMTS also creates a global timing reference by transmitting the time synchronization (SYNC) and upstream channel descriptor (UCD) MAC messages downstream at a nominal frequency (see clause 6.2.11.2).
+
+The transmission convergence sublayer must operate closely with the MAC sublayer to provide an accurate timestamp for the SYNC message. As mentioned in the ranging clause below (see 9.3.3), the model assumes that the timing delays through the remainder of the PHY layer MUST be relatively constant with the exception of the timing offsets specified in clause 6.2.19.4 related to modulation rate changes to accommodate a legacy DOCSIS upstream receiver implementation. For TDMA, any variation in the PHY delays MUST be accounted for in the guard time of the PHY overhead.
+
+It is intended that the nominal interval between SYNC messages be tens of milliseconds and the nominal interval between UCD messages be no more than 2 seconds. This imposes very little downstream overhead while letting cable modems acquire their global timing synchronization quickly.
+
+### **9.3.2 CM channel acquisition**
+
+Any cable modem MUST NOT use the upstream channel until it has successfully synchronized to the downstream.
+
+First, the cable modem MUST establish PMD sublayer synchronization. This implies that it has locked onto the correct frequency, equalized the downstream channel, recovered any PMD sublayer framing and the FEC is operational (refer to clause 11.2.2). At this point, a valid bit stream is being sent to the transmission convergence sublayer. The transmission convergence sublayer performs its own synchronization (see clause 7). On detecting the well-known DOCS PID, along with a payload unit start indicator per [ITU-T H.222.0], it delivers the MAC frame to the MAC sublayer.
+
+The MAC sublayer MUST now search for the timing synchronization (SYNC) MAC management messages. For TDMA channels, the cable modem achieves MAC synchronization once it has received at least two SYNC messages and has verified that its clock tolerances are within specified limits. For S-CDMA channels, the cable modem achieves MAC synchronization once it has received at least two SYNC messages, received one UCD message, and has locked to the downstream symbol clock and verified that its clock tolerances are within specified limits.
+
+A cable modem remains in "SYNC" as long as it continues to successfully receive the SYNC messages. If the lost SYNC interval (refer to Annex B) has elapsed without a valid SYNC message, a cable modem MUST NOT use the upstream and MUST try to re-establish synchronization again.
+
+### **9.3.3 Ranging**
+
+Ranging is the process of acquiring the correct timing offset such that the cable modem's transmissions are aligned to the correct mini-slot boundary. The timing delays through the PHY layer MUST be relatively constant with the exception of the timing offsets specified in clause 6.2.19.4 related to modulation rate changes to accommodate a legacy DOCSIS upstream receiver implementation. For TDMA, any variation in the PHY delays MUST be accounted for in the guard time of the upstream PMD overhead.
+
+#### **9.3.3.1 Broadcast initial ranging**
+
+First, a cable modem MUST synchronize to the downstream and learn the upstream channel characteristics through the upstream channel descriptor MAC management message. At this point, the cable modem MUST scan the bandwidth allocation MAP message to find a broadcast initial maintenance region. Refer to clause 9.1.2.4. The CMTS MUST make a broadcast initial
+
+maintenance region large enough to account for the variation in delays between any two CMs. On S-CDMA channels, the CMTS MUST schedule broadcast initial maintenance transmit opportunities such that they align with S-CDMA frames and span an integral number of S-CDMA frames. Refer to clause 6.2.11.5.
+
+The cable modem MUST put together either an initial ranging request message or a ranging request message to be sent in a broadcast initial maintenance region. An INIT-RNG-REQ MUST be transmitted if the upstream is a DOCS 2.0-only upstream, which can be determined from the UCD. Otherwise a RNG-REQ MUST be transmitted. The SID field MUST be set to the non-initialized CM value (zero), unless this initial ranging is a result of a UCD ranging required TLV or a DCC or UCC request in which the CM has been instructed to retain its existing SIDs.
+
+The CM MUST set its initial timing offset to the amount of internal fixed delay equivalent to putting this CM next to the CMTS. This amount includes delays introduced through a particular implementation, and MUST include the downstream PHY interleaving latency. When the broadcast initial maintenance transmit opportunity occurs, the cable modem MUST send the INIT-RNG-REQ or RNG-REQ message. Thus, the cable modem sends the message as if it were physically right at the CMTS.
+
+Once the CMTS has successfully received the RNG-REQ or INIT-RNG-REQ message, it MUST return a ranging response message addressed to the individual cable modem. Within the ranging response message MUST be a temporary SID assigned to this cable modem (unless the CM has retained a previous primary SID during a UCC, DCC or UCD change) until it has completed the registration process. The message MUST also contain information on RF power level adjustment and offset frequency adjustment as well as any timing offset corrections. Ranging adjusts each CM's timing offset such that it appears to be located right next to the CMTS.
+
+### 9.3.3.2 Unicast initial ranging
+
+The cable modem MUST now wait for an individual station maintenance or unicast initial maintenance region assigned to its temporary SID (or previous primary SID if ranging as a result of a UCC, DCC or UCD change). It MUST now transmit a ranging request message at this time using the temporary SID (or previous primary SID) along with any power level and timing offset corrections.
+
+The CMTS MUST return another ranging response message to the cable modem with any additional fine tuning required. The ranging request/response steps MUST be repeated until the response contains a ranging successful notification or the CMTS aborts ranging. Once successfully ranged, the cable modem MUST join normal data traffic in the upstream. See clause 11 for complete details on the entire initialization sequence. In particular, state machines and the applicability of retry counts and timer values for the ranging process are defined in clause 11.2.4.
+
+NOTE – The burst type to use for any transmission is defined by the interval usage code (IUC). Each IUC is mapped to a burst type in the UCD message.
+
+### 9.3.4 Timing units and relationships
+
+The SYNC message conveys a time reference with a resolution of 6.25/64 microseconds (10.24 MHz) to allow the CM to track the CMTS clock with a small phase offset. Since this timing reference is decoupled from particular upstream channel characteristics, a single SYNC time reference may be used for all upstream channels associated with the downstream channel.
+
+The bandwidth allocation MAP uses time units of "mini-slots." A mini-slot represents the time needed for transmission of a fixed number of symbols. For some modulations (e.g., QPSK), an integer number of bytes can be transmitted in a mini-slot. For these channels, the mini-slot is expected to represent 16 byte-times, although other values could be chosen.
+
+A "mini-slot" is the unit of granularity for upstream transmission opportunities; there is no implication that any PDU can actually be transmitted in a single mini-slot.
+
+### 9.3.4.1 TDMA timing units and relationships
+
+#### 9.3.4.1.1 Mini-slot capacity
+
+On TDMA channels, the size of the mini-slot, expressed as a multiple of the SYNC time reference, is carried in the upstream channel descriptor. The example in Table 9-2 relates mini-slots to the SYNC time ticks (assuming QPSK modulation):
+
+**Table 9-2 – Example relating mini-slots to time ticks**
+
+| Parameter              | Example value                            |
+|------------------------|------------------------------------------|
+| Time tick              | 6.25 microseconds                        |
+| Bytes per mini-slot    | 16 (nominal, when using QPSK modulation) |
+| Symbols/byte           | 4 (assuming QPSK)                        |
+| Symbols/second         | 2 560 000                                |
+| Mini-slots/second      | 40 000                                   |
+| Microseconds/mini-slot | 25                                       |
+| Ticks/mini-slot        | 4                                        |
+
+Note that the symbols/byte is a characteristic of an individual burst transmission, not of the channel. A mini-slot in this instance could represent a minimum of 16 or a maximum of 48 bytes, depending on the modulation choice.
+
+In a channel allocated exclusively to DOCS 2.0 TDMA modems, the mini-slot size field of the UCD MAY take on the value 0, in which case the mini-slot size is 1 timebase tick. If a channel is to be accessible to both DOCS 1.x and 2.0 TDMA cable modems, the UCD MUST follow the DOCS 1.x requirements for timing units and relationships.
+
+#### 9.3.4.1.2 Mini-slot numbering
+
+The MAP counts mini-slots in a 32-bit counter that normally counts to  $(2^{32} - 1)$  and then wraps back to zero. The least-significant bits (i.e., bit 0 to bit 25-M) of the mini-slot counter MUST match the most-significant bits (i.e., bit 6 + M to bit 31) of the SYNC timestamp counter. That is, mini-slot N begins at timestamp reference  $(N \times T \times 64)$ , where  $T = 2^M$  is the UCD multiplier that defines the mini-slot (i.e., the number of time ticks per mini-slot).
+
+NOTE 1 – The unused upper bits of the 32-bit mini-slot counter (i.e., bit 26-M to bit 31) are not needed by the CM and MAY be ignored.
+
+NOTE 2 – The constraint that the UCD multiplier be a power of two has the consequence that the number of bytes per mini-slot must also be a power of two.
+
+### 9.3.4.2 S-CDMA timing units and relationships
+
+#### 9.3.4.2.1 Mini-slot capacity
+
+On S-CDMA channels, the size of the mini-slot is dependent on the modulation rate, the codes per mini-slot, and the spreading intervals per frame, which are all carried in the upstream channel descriptor. The timing units and relationships for S-CDMA are covered in detail in clause 6.2.11, "S-CDMA framer and interleaver". An example of the timing relationships (assuming 64QAM modulation) is shown in Table 9-3:
+
+**Table 9-3 – Example of mini-slot capacity in S-CDMA mode**
+
+| Parameter                     | Example value                             |
+|-------------------------------|-------------------------------------------|
+| Spreading intervals per frame | 10                                        |
+| Active code length            | 128                                       |
+| Codes per mini-slot           | 4                                         |
+| Mini-slots per frame          | 32                                        |
+| Symbols per mini-slot         | 40                                        |
+| Bytes per mini-slot           | 30 (nominal, when using 64QAM modulation) |
+| Bits/symbol                   | 6 (assuming 64QAM)                        |
+| Symbols/second                | 5 120 000                                 |
+| Mini-slots/second             | 128 000                                   |
+| Microseconds/mini-slot        | 7.8125                                    |
+
+#### 9.3.4.2.2 Mini-slot numbering
+
+Mini-slot numbering in S-CDMA mode is described in detail in clause 6.2.11.2.
+
+### 9.4 Upstream transmission and contention resolution
+
+The CMTS controls assignments on the upstream channel through the MAP and determines which mini-slots are subject to collisions. The CMTS MAY allow collisions on either requests or data PDUs.
+
+This clause provides an overview of upstream transmission and contention resolution. For simplicity, it refers to the decisions a CM makes; however, this is just a pedagogical tool. Since a CM can have multiple upstream service flows (each with its own SID) it makes these decisions on a per service queue or per SID basis. Refer to Appendix IV for a state transition diagram and more detail.
+
+#### 9.4.1 Contention resolution overview
+
+The mandatory method of contention resolution which MUST be supported is based on a truncated binary exponential back-off, with the initial back-off window and the maximum back-off window controlled by the CMTS. The values are specified as part of the bandwidth allocation map (MAP) MAC message and represent a power-of-two value. For example, a value of 4 indicates a window between 0 and 15; a value of 10 indicates a window between 0 and 1023.
+
+Every time a CM wants to transmit in a contention region, it MUST enter the contention resolution process by setting its internal back-off window equal to the data backoff start defined in the MAP currently in effect<sup>18</sup>.
+
+The CM MUST randomly select a number within its back-off window. This random value indicates the number of contention transmit opportunities that the CM MUST defer before transmitting. A CM MUST only consider contention transmit opportunities for which this transmission would have been eligible. These are defined by either request IEs or request/data IEs in the MAP.
+
+NOTE 1 – Each IE can represent multiple transmission opportunities.
+
+As an example, consider a CM whose initial back-off window is 0 to 15 and it randomly selects the number 11. The CM must defer a total of 11 contention transmission opportunities. If the first available request IE is for 6 requests, the CM does not use this and has 5 more opportunities to
+
+---
+
+<sup>18</sup> The MAP currently in effect is the MAP whose allocation start time has occurred but which includes IEs that have not occurred.
+
+defer. If the next request IE is for 2 requests, the CM has 3 more to defer. If the third request IE is for 8 requests, the CM transmits on the fourth request, after deferring for 3 more opportunities.
+
+After a contention transmission, the CM waits for a data grant (data grant pending) or data acknowledge in a subsequent MAP. Once either is received, the contention resolution is complete. The CM determines that the contention transmission was lost when it finds a MAP without a data grant (data grant pending) or data acknowledge for it and with an ack time more recent than the time of transmission<sup>19</sup>. The CM MUST now increase its back-off window by a factor of two, as long as it is less than the maximum back-off window. The CM MUST randomly select a number within its new back-off window and repeat the deferring process described above.
+
+This re-try process continues until the maximum number of retries (16) has been reached, at which time the PDU MUST be discarded.
+
+NOTE 2 – The maximum number of retries is independent of the initial and maximum back-off windows that are defined by the CMTS.
+
+If the CM receives a unicast request or data grant at any time while deferring for this SID, it MUST stop the contention resolution process and use the explicit transmit opportunity.
+
+The CMTS has much flexibility in controlling the contention resolution. At one extreme, the CMTS may choose to set up the data backoff start and end to emulate an Ethernet-style back-off with its associated simplicity and distributed nature, but also its fairness and efficiency issues. This would be done by setting data backoff start = 0 and end = 10 in the MAP. At the other end, the CMTS may make the data backoff start and end identical and frequently update these values in the MAP so all cable modems are using the same, and hopefully optimal, back-off window.
+
+A CM transmitting a RNG-REQ in the initial maintenance IE MUST perform truncated binary exponential backoff using the ranging backoff start and ranging backoff end to control the backoff window. The algorithm works similarly to data transmissions, except on the calculation of transmit opportunities, which is described in the next clause.
+
+#### 9.4.2 Transmit opportunities
+
+A transmit opportunity is defined as any mini-slot in which a CM may be allowed to start a transmission. Transmit opportunities typically apply to contention opportunities and are used to calculate the proper amount to defer in the contention resolution process.
+
+The number of transmit opportunities associated with a particular IE in a MAP is dependent on the total size of the region as well as the allowable size of an individual transmission. As an example, assume a contention REQ IE defines a region of 12 mini-slots. If the UCD defines a REQ burst size that fits into a single mini-slot then there are 12 transmit opportunities associated with this REQ IE, i.e., one for each mini-slot. If the UCD defines a REQ that fits in two mini-slots, then there are six transmit opportunities and a REQ can start on every other mini-slot.
+
+As another example, assume a REQ/data IE that defines a 24 mini-slot region. If it is sent with an SID of 0x3FF4 (refer to Annex A), then a CM can potentially start a transmit on every fourth mini-slot; so this IE contains a total of six transmit opportunities (TX OPs). Similarly, a SID of 0x3FF6 implies four TX OPs; 0x3FF8 implies three TX OPs; and 0x3FFC implies two TX OPs.
+
+For a broadcast initial maintenance IE, a CM MUST start its transmission in the first mini-slot of the region; therefore it has a single transmit opportunity. The remainder of the region is used to compensate for the round-trip delays since the CM has not yet been ranged.
+
+---
+
+<sup>19</sup> Data acknowledge IEs are intended for collision detection only and are not designed for providing reliable transport (that is the responsibility of higher layers). If a MAP is lost or damaged, a CM waiting for a data acknowledge MUST assume that its contention data transmission was successful and MUST NOT retransmit the data packet. This prevents the CM from sending duplicate packets unnecessarily.
+
+Station maintenance IEs, short/long data grant IEs, adv PHY short/long data grant IEs, adv PHY unsolicited grant IEs, unicast initial maintenance, and unicast request IEs are unicast and thus are not typically associated with contention transmit opportunities. They represent a single dedicated, or reservation-based, transmit opportunity.
+
+In summary:
+
+**Table 9-4 – Transmit opportunity**
+
+| Interval            | SID type             | Transmit opportunity                |
+|---------------------|----------------------|-------------------------------------|
+| Request             | Broadcast            | # mini-slots required for a request |
+| Request             | Multicast            | # mini-slots required for a request |
+| Request/data        | Broadcast            | Not allowed                         |
+| Request/data        | Well-known multicast | As defined by SID in Annex A        |
+| Request/data        | Multicast            | Vendor-specific algorithms          |
+| Initial maintenance | Broadcast            | Entire interval is a single TX OP   |
+
+NOTE – Transmit opportunity should not be confused with burst size. Burst size requirements are specified in Table 6-1.
+
+#### 9.4.3 CM bandwidth utilization
+
+The following rules govern the response a CM makes when processing maps.
+
+NOTE – These standard behaviours can be overridden by the CM's request/transmission policy (refer to clause C.2.2.6.3):
+
+- 1) A CM MUST first use any grants assigned to it. Next, the CM MUST use any unicast REQ for it. Finally, the CM MUST use the next available broadcast/multicast REQ or REQ/data IEs for which it is eligible.
+- 2) A CM MUST NOT have more than one request outstanding at a time for a particular service ID.
+- 3) If a CM has a request pending, it MUST NOT use intervening contention intervals for that service ID.
+
+### 9.5 Data link encryption support
+
+The procedures to support data link encryption are defined in [DOCS8]. The interaction between the MAC layer and the security system is limited to the items defined below.
+
+#### 9.5.1 MAC messages
+
+MAC management messages (see clause 8.3) MUST NOT be encrypted, except for certain cases where such a frame is included in a fragmented concatenated burst on the upstream (refer to clause 8.2.7.1)
+
+#### 9.5.2 Framing
+
+The following rules MUST be followed when encryption is applied to a data PDU:
+
+- Privacy EH element of [DOCS8] MUST be in the extended header and MUST be the first EH element of the extended header field (EHDR).
+- Encrypted data are carried as data PDUs to the cable MAC transparently.
+
+## 10 Quality of service and fragmentation
+
+This Recommendation introduces several new quality of service (QoS) related concepts not present in the original March 1998 version of J.112 Annex B. These include:
+
+- packet classification and flow identification;
+- service flow QoS scheduling;
+- dynamic service establishment;
+- fragmentation;
+- two-phase activation model.
+
+### 10.1 Theory of operation
+
+The various DOCS protocol mechanisms described in this Recommendation can be used to support quality of service (QoS) for both upstream and downstream traffic through the CM and the CMTS. This clause provides an overview of the QoS protocol mechanisms and their part in providing end-to-end QoS.
+
+The requirements for quality of service include:
+
+- a configuration and registration function for pre-configuring CM-based QoS **service flows** and traffic parameters;
+- a signalling function for dynamically establishing QoS-enabled service flows and traffic parameters;
+- a traffic-shaping and traffic-policing function for service flow-based traffic management, performed on traffic arriving from the upper layer service interface and outbound to the RF;
+- utilization of MAC scheduling and traffic parameters for upstream service flows;
+- utilization of QoS traffic parameters for downstream service flows;
+- classification of packets arriving from the upper layer service interface to a specific active service flow;
+- grouping of service flow properties into named **service classes**, so upper layer entities and external applications (at both the CM and CMTS) can request service flows with desired QoS parameters in a globally consistent way.
+
+The principal mechanism for providing enhanced QoS is to classify packets traversing the RF MAC interface into a **service flow**. A service flow is a unidirectional flow of packets that is provided a particular quality of service. The CM and CMTS provide this QoS by shaping, policing and prioritizing traffic according to the **QoS parameter set** defined for the service flow.
+
+The primary purpose of the quality of service features defined here is to define transmission ordering and scheduling on the radio frequency interface. However, these features often need to work in conjunction with mechanisms beyond the RF interface in order to provide end-to-end QoS or to police the behaviour of cable modems. For example, the following behaviours are permitted:
+
+- Policies may be defined by CM MIBs which overwrite the ToS byte. Such policies are outside the scope of the RFI Recommendation. In the upstream direction, the CMTS polices the ToS byte setting regardless of how the ToS byte is derived or by whom it is written (originator or CM policy).
+- The queueing of service flow packets at the CMTS in the downstream direction may be based on the ToS byte.
+- Downstream service flows can be reclassified by the CM to provide enhanced service onto the subscriber-side network.
+
+Service flows exist in both the upstream and downstream direction, and may exist without actually being activated to carry traffic. Service flows have a 32-bit **service flow identifier** (SFID) assigned by the CMTS. All service flows have an SFID; active and admitted upstream service flows also have a 14-bit service identifier (SID).
+
+At least two service flows must be defined in each configuration file: one for upstream and one for downstream service. The first upstream service flow describes the **primary upstream service flow**, and is the default service flow used for otherwise unclassified traffic, including both MAC management messages and data PDUs. The first downstream service flow describes service to the primary downstream service flow. Additional service flows defined in the configuration file create service flows that are provided QoS services.
+
+Conceptually, incoming packets are matched to a **classifier** that determines to which QoS service flow the packet is forwarded. The classifier can examine the LLC header of the packet, the IP/TCP/UDP header of the packet or some combination of the two. If the packet matches one of the classifiers, it is forwarded to the service flow indicated by the SFID attribute of the classifier. If the packet is not matched to a classifier, it is forwarded on the primary service flow.
+
+### 10.1.1 Concepts
+
+#### 10.1.1.1 Service flows
+
+A service flow is a MAC-layer transport service that provides unidirectional transport of packets either to upstream packets transmitted by the CM or to downstream packets transmitted by the CMTS<sup>20</sup>. A service flow is characterized by a set of **QoS parameters** such as latency, jitter and throughput assurances. In order to standardize operation between the CM and CMTS, these attributes include details of how the CM requests upstream mini-slots and the expected behaviour of the CMTS upstream scheduler.
+
+A service flow is partially characterized by the following attributes<sup>21</sup>:
+
+- **ServiceFlowID**: Exists for all service flows.
+- **ServiceID**: Only exists for admitted or active upstream service flows.
+- **ProvisionedQosParamSet**: Defines a set of QoS parameters that appears in the configuration file and is presented during registration. This MAY define the initial limit for authorizations allowed by the authorization module. The ProvisionedQosParamSet is defined once when the service flow is created via registration<sup>22</sup>.
+- **AdmittedQosParamSet**: Defines a set of QoS parameters for which the CMTS (and possibly the CM) are reserving resources. The principal resource to be reserved is bandwidth, but this also includes any other memory or time-based resource required to subsequently activate the flow.
+- **ActiveQosParamSet**: Defines a set of QoS parameters defining the service actually being provided to the service flow. Only an active service flow may forward packets.
+
+---
+
+<sup>20</sup> A service flow, as defined here, has no direct relationship to the concept of a "flow" as defined by the IETF's integrated services (intserv) working group [b-RFC 2212]. An intserv flow is a collection of packets sharing transport-layer endpoints. Multiple intserv flows can be served by a single service flow. However, the classifiers for a service flow may be based on 802.1P/Q criteria, and so may not involve intserv flows at all.
+
+<sup>21</sup> Some attributes are derived from the above attribute list. The service class name is an attribute of the ProvisionedQoSParamSet. The activation state of the service flow is determined by the ActiveQoSParamSet. If the ActiveQoSParamSet is null then the service flow is inactive.
+
+<sup>22</sup> The ProvisionedQoSParamSet is null when a flow is created dynamically.
+
+A service flow exists when the CMTS assigns a service flow ID (SFID) to it. The SFID serves as the principal identifier in the CM and CMTS for the service flow. A service flow which exists has at least an SFID, and an associated direction.
+
+The **authorization module** is a logical function within the CMTS that approves or denies every change to QoS parameters and classifiers associated with a service flow. As such, it defines an "envelope" that limits the possible values of the AdmittedQosParamSet and ActiveQosParamSet.
+
+The relationship between the QoS parameter sets is as shown in Figures 10-1 and 10-2. The ActiveQosParamSet is always a subset<sup>23</sup> of the AdmittedQosParamSet which is always a subset of the authorized "envelope." In the dynamic authorization model, this envelope is determined by the authorization module (labelled as the AuthQosParamSet). In the provisioned authorization model, this envelope is determined by the ProvisionedQosParamSet (refer to clause 10.1.4 for further information on the authorization models).
+
+![Diagram illustrating the provisioned authorization model envelopes. It shows three nested boxes: the outermost dashed box is labeled 'AuthQosParamSet = ProvisionedQosParamSet (SFID)'; the middle solid box is labeled 'AdmittedQosParamSet (SFID and SID)'; and the innermost solid box is labeled 'ActiveQosParamSet (SFID and Active SID)'.](573293af67ee571aef04bf725fcefbe5_img.jpg)
+
+The diagram illustrates the relationship between three nested QoS parameter sets in the provisioned authorization model. It consists of three concentric rectangles. The outermost rectangle has a dashed border and is labeled "AuthQosParamSet = ProvisionedQosParamSet (SFID)". Inside it is a solid-bordered rectangle labeled "AdmittedQosParamSet (SFID and SID)". Inside that is another solid-bordered rectangle labeled "ActiveQosParamSet (SFID and Active SID)". The labels are positioned in the top-left corner of each respective rectangle.
+
+Diagram illustrating the provisioned authorization model envelopes. It shows three nested boxes: the outermost dashed box is labeled 'AuthQosParamSet = ProvisionedQosParamSet (SFID)'; the middle solid box is labeled 'AdmittedQosParamSet (SFID and SID)'; and the innermost solid box is labeled 'ActiveQosParamSet (SFID and Active SID)'.
+
+J.122\_F10-1
+
+**Figure 10-1 – Provisioned authorization model "envelopes"**
+
+<sup>23</sup> To say that QoS parameter set A is a subset of QoS parameter set B, the following MUST be true for all QoS parameters in A and B:
+
+- If a smaller QoS parameter value indicates less resources (e.g., maximum traffic rate), A is a subset of B if the parameter in A less than or equal to the same parameter in B.
+- If a larger QoS parameter value indicates less resources (e.g., tolerated grant jitter), A is a subset of B if the parameter in A is greater than or equal to the same parameter in B.
+- If the QoS parameter specifies a periodic interval (e.g., nominal grant interval), A is a subset of B if the parameter in A is an integer multiple of the same parameter in B.
+- If the QoS parameter is not quantitative (e.g., service flow scheduling type), A is a subset of B if the parameter in A is equal to the same parameter in B.
+
+![Figure 10-2: Dynamic authorization model 'envelopes' diagram. It shows four nested boxes representing different QoS parameter sets. The outermost box is 'ProvQosParamSet (SFID)'. Inside it is 'AuthQosParamSet (CMTS only, not known by CM)'. Inside that is 'AdmitQosParamSet (SFID and SID)'. The innermost box is 'ActiveQosParamSet (SFID and active SID)'. The boxes are nested and slightly offset to the right and down. A label 'J.122_F10-2' is at the bottom right.](f6944ef450a5560fc697a86a01b70b36_img.jpg)
+
+Figure 10-2: Dynamic authorization model 'envelopes' diagram. It shows four nested boxes representing different QoS parameter sets. The outermost box is 'ProvQosParamSet (SFID)'. Inside it is 'AuthQosParamSet (CMTS only, not known by CM)'. Inside that is 'AdmitQosParamSet (SFID and SID)'. The innermost box is 'ActiveQosParamSet (SFID and active SID)'. The boxes are nested and slightly offset to the right and down. A label 'J.122\_F10-2' is at the bottom right.
+
+**Figure 10-2 – Dynamic authorization model "envelopes"**
+
+It is useful to think of three types of service flows:
+
+- **Provisioned:** this type of service flow is known via provisioning through the configuration file, its AdmittedQosParamSet and ActiveQosParamSet are both null. A **provisioned service flow** may or may not have associated classifiers. If a provisioned service flow has associated classifiers, the classifiers **MUST NOT** be used to classify packets onto the flow, regardless of the classifier's activation state.
+- **Admitted:** this type of service flow has resources reserved by the CMTS for its AdmittedQosParamSet, but these parameters are not active (its ActiveQosParamSet is null). **Admitted service flows** may have been provisioned or may have been signalled by some other mechanism. Generally, admitted service flows have associated classifiers, however, it is possible for admitted service flows to use policy-based classification. If admitted service flows have associated classifiers, the classifiers **MUST NOT** be used to classify packets onto the flow, regardless of the classifier's activation state.
+- **Active:** this type of service flow has resources committed by the CMTS for its QoS parameter set, (e.g., is actively sending MAPs containing unsolicited grants for a UGS-based service flow). Its ActiveQosParamSet is non-null. Generally, active service flows have associated classifiers; however, it is possible for active service flows to use policy-based classification. primary service flows may have associated classifiers(s), but in addition to any packets matching such classifiers, all packets that fail to match any classifier will be sent on the primary service flow for that direction.
+
+#### 10.1.1.2 Classifiers
+
+A **classifier** is a set of matching criteria applied to each packet entering the cable network. It consists of some packet-matching criteria (destination IP address, for example), a **classifier priority**, and a reference to a service flow. If a packet matches the specified packet matching criteria, it is then delivered on the referenced service flow.
+
+Several classifiers may all refer to the same service flow. The classifier priority is used for ordering the application of classifiers to packets. Explicit ordering is necessary because the patterns used by classifiers may overlap. The priority need not be unique, but care must be taken within a classifier priority to prevent ambiguity in classification (refer to clause 10.1.6.1). **Downstream classifiers** are applied by the CMTS to packets it is transmitting, and **upstream classifiers** are applied at the CM and may be applied at the CMTS to police the classification of upstream packets. Figure 10-3 illustrates the mappings discussed above.
+
+![Diagram illustrating classification within the MAC layer for CMTS and CM entities. The diagram shows two main components: CMTS (left) and CM (right), connected by a central RF (Radio Frequency) section. On the CMTS side, an 'Upper-layer entity (e.g. bridge, router)' is connected to a 'Downstream classifier'. The classifier directs traffic to multiple service flows labeled 'Primary SFID', 'SFID 2', '...', 'SFID n', collectively labeled 'Downstream service flows'. MAC Management Messages are also shown. On the CM side, an 'Upper layer entity (e.g. bridge, router, client)' is connected to an '(Optional) ingress classifier'. This classifier directs traffic to service flows labeled 'Primary SID', 'SID 2', '...', 'SID n', collectively labeled 'Upstream service flows'. MAC Management Messages are also shown. Both sides have an 'Upstream classifier' that directs traffic from the service flows back towards the upper-layer entity. The central RF section has 'Downstream' and 'Upstream' arrows indicating the direction of traffic flow between the CMTS and CM.](1582c665ca9405e127473c291eaed480_img.jpg)
+
+Diagram illustrating classification within the MAC layer for CMTS and CM entities. The diagram shows two main components: CMTS (left) and CM (right), connected by a central RF (Radio Frequency) section. On the CMTS side, an 'Upper-layer entity (e.g. bridge, router)' is connected to a 'Downstream classifier'. The classifier directs traffic to multiple service flows labeled 'Primary SFID', 'SFID 2', '...', 'SFID n', collectively labeled 'Downstream service flows'. MAC Management Messages are also shown. On the CM side, an 'Upper layer entity (e.g. bridge, router, client)' is connected to an '(Optional) ingress classifier'. This classifier directs traffic to service flows labeled 'Primary SID', 'SID 2', '...', 'SID n', collectively labeled 'Upstream service flows'. MAC Management Messages are also shown. Both sides have an 'Upstream classifier' that directs traffic from the service flows back towards the upper-layer entity. The central RF section has 'Downstream' and 'Upstream' arrows indicating the direction of traffic flow between the CMTS and CM.
+
+J.122\_F10-3
+
+**Figure 10-3 – Classification within the MAC layer**
+
+CM and CMTS packet classification consists of multiple classifiers. Each classifier contains a priority field which determines the search order for the classifier. The highest priority classifier MUST be applied first. If a classifier is found in which all parameters match the packet, the classifier MUST forward the packet to the corresponding service flow (irrelevant parameters – as defined in clause C.2.1 – have no impact on packet classification decisions). If a classifier contains no relevant parameters for a given packet (i.e., all parameters are irrelevant), then that packet cannot match the classifier, and the classifier MUST NOT forward the packet to the corresponding service flow. If a packet does not match any classifier and, as a result, has not been classified to any other flow, then it MUST be classified to the primary service flow.
+
+The packet classification table contains the following fields:
+
+- Priority – Determines the search order for the table. Higher priority classifiers are searched before lower priority classifiers.
+- IP classification parameters – Zero or more of the IP classification parameters (IP ToS range/mask, IP protocol, IP source address/mask, IP destination address/mask, TCP/UDP source port start, TCP/UDP source port end, TCP/UDP destination port start, TCP/UDP destination port end).
+- LLC classification parameters – Zero or more of the LLC classification parameters (destination MAC address, source MAC address, ethertype/SAP).
+- IEEE 802.1P/Q parameters – Zero or more of the IEEE classification parameters (802.1P priority range, 802.1Q VLAN ID).
+- Service flow identifier – Identifier of a specific flow to which this packet is to be directed.
+
+Classifiers can be added to the table either via management operations (configuration file, registration) or via dynamic operations (dynamic signalling, DOCS MAC sublayer service interface). SNMP-based operations can view classifiers that are added via dynamic operations, but cannot modify or delete classifiers that are created by dynamic operations. The format for classification table parameters defined in the configuration file, registration message or dynamic signalling message is contained in Annex C.
+
+Classifier attributes include an activation state (see clause C.2.1.3.6). The 'inactive' setting may be used to reserve resources for a classifier which is to be activated later. The actual activation of the classifier depends both on this attribute and on the state of its service flow. If the service flow is not active then the classifier is not used, regardless of the setting of this attribute.
+
+### 10.1.2 Object model
+
+The major objects of the architecture are represented by named rectangles in Figure 10-4. Each object has a number of attributes; the attribute names that uniquely identify the object are underlined. Optional attributes are denoted with brackets. The relationship between the number of objects is marked at each end of the association line between the objects. For example, a service flow may be associated with from 0 to 65535 classifiers, but a classifier is associated with exactly one service flow.
+
+![UML Class Diagram showing the Theory of operation object model. The diagram includes five classes: Packet, Classifier, Service Flow, PayloadHeader Suppression (PHS), and Service Class. Packet has attributes: LlHeader, [IpHeader], [SClass], [RulePriority], [SFID]. Classifier has attributes: SFID, ClassifierId, LlPacketPattern, IpPacketPattern, RulePriority. Service Flow has attributes: SFID, Direction, [SID], [ProvQosParamSet], [AdmittedQosParamSet], [ActiveQosParamSet]. PayloadHeader Suppression (PHS) has attributes: SFID, PHSI, ClassifierId, PHSF, PHSM, PHSS, PHSV. Service Class has attributes: Service Class Name, QosParamSet. Relationships: Packet 'matches' Classifier; Classifier is associated with Service Flow (0..65535 to 1); Classifier is associated with PHS (0,1 to 0..255); Service Flow is associated with Service Class (1 to N); Service Flow is associated with PHS (1 to 0,1). A dashed line connects Packet and Service Flow.](e1e41cc8c8434891237529fedcbba418_img.jpg)
+
+```
+
+classDiagram
+    class Packet {
+        LlHeader
+        [IpHeader]
+        [SClass]
+        [RulePriority]
+        [SFID]
+    }
+    class Classifier {
+        SFID
+        ClassifierId
+        LlPacketPattern
+        IpPacketPattern
+        RulePriority
+    }
+    class ServiceFlow {
+        SFID
+        Direction
+        [SID]
+        [ProvQosParamSet]
+        [AdmittedQosParamSet]
+        [ActiveQosParamSet]
+    }
+    class PHS {
+        SFID
+        PHSI
+        ClassifierId
+        PHSF
+        PHSM
+        PHSS
+        PHSV
+    }
+    class ServiceClass {
+        Service Class Name
+        QosParamSet
+    }
+
+    Packet --> Classifier : matches
+    Classifier --> ServiceFlow : 0..65535 to 1
+    Classifier --> PHS : 0,1 to 0..255
+    ServiceFlow --> ServiceClass : 1 to N
+    ServiceFlow --> PHS : 1 to 0,1
+    Packet -.-> ServiceFlow
+  
+```
+
+UML Class Diagram showing the Theory of operation object model. The diagram includes five classes: Packet, Classifier, Service Flow, PayloadHeader Suppression (PHS), and Service Class. Packet has attributes: LlHeader, [IpHeader], [SClass], [RulePriority], [SFID]. Classifier has attributes: SFID, ClassifierId, LlPacketPattern, IpPacketPattern, RulePriority. Service Flow has attributes: SFID, Direction, [SID], [ProvQosParamSet], [AdmittedQosParamSet], [ActiveQosParamSet]. PayloadHeader Suppression (PHS) has attributes: SFID, PHSI, ClassifierId, PHSF, PHSM, PHSS, PHSV. Service Class has attributes: Service Class Name, QosParamSet. Relationships: Packet 'matches' Classifier; Classifier is associated with Service Flow (0..65535 to 1); Classifier is associated with PHS (0,1 to 0..255); Service Flow is associated with Service Class (1 to N); Service Flow is associated with PHS (1 to 0,1). A dashed line connects Packet and Service Flow.
+
+Figure 10-4 – Theory of operation object model
+
+The service flow is the central concept of the MAC protocol. It is uniquely identified by a 32-bit service flow ID (SFID) assigned by the CMTS. Service flows may be in either the upstream or downstream direction. A unicast service identifier (SID) is a 14-bit index, assigned by the CMTS, which is associated with one, and only one, admitted upstream service flow.
+
+Typically, an outgoing user data packet is submitted by an upper layer protocol (such as the forwarding bridge of a CM) for transmission on the cable MAC interface. The packet is compared against a set of classifiers. The matching classifier for the packet identifies the corresponding service flow via the service flow ID (SFID). In the case where more than one classifier matches the packet, the highest priority classifier is chosen.
+
+The classifier matching a packet may be associated with a payload header suppression rule. A PHS rule provides details on how header bytes of a packet PDU can be omitted, replaced with a payload header suppression index for transmission, and subsequently regenerated at the receiving end. PHS rules are indexed by the combination of {SFID, PHSI} (refer to clause 10.4). When a service flow is deleted, all classifiers and any associated PHS rules referencing it MUST also be deleted.
+
+The service class is an optional object that MUST be implemented at the CMTS. It is referenced by an ASCII name which is intended for provisioning purposes. A service class is defined in the CMTS to have a particular QoS parameter Set. A service flow may contain a reference to the service class name that selects all of the QoS parameters of the service class. The service flow QoS parameter sets may augment and even override the QoS parameter settings of the service class, subject to authorization by the CMTS (refer to clause C.2.2.5).
+
+If a packet has already been determined by upper layer policy mechanisms to be associated with a particular service class name/priority combination, that combination associates the packet with a particular service flow directly (refer to clause 10.1.6.1). The upper layer may also be aware of the particular service flows in the MAC sublayer, and may have assigned the packet directly to a service flow. In these cases, a user data packet is considered to be directly associated with a service flow as selected by the upper layer. This is depicted with the dashed arrow in Figure 10-4 (refer to Appendix I).
+
+### 10.1.3 Service classes
+
+The QoS attributes of a service flow may be specified in two ways: either by explicitly defining all attributes, or implicitly by specifying a **service class name**. A service class name is a string which the CMTS associates with a QoS parameter set. It is described further below.
+
+The service class serves the following purposes:
+
+- 1) It allows operators, who so wish, to move the burden of configuring service flows from the provisioning server to the CMTS. Operators provision the modems with the service class name; the implementation of the name is configured at the CMTS. This allows operators to modify the implementation of a given service to local circumstances without changing modem provisioning. For example, some scheduling parameters may need to be tweaked differently for two different CMTSs to provide the same service. As another example, service profiles could be changed by time of day.
+- 2) It allows CMTS vendors to provide class-based-queuing if they choose, where service flows compete within their class and classes compete with each other for bandwidth.
+- 3) It allows higher-layer protocols to create a service flow by its service class name. For example, telephony signalling may direct the CM to instantiate any available provisioned service flow of class "G711".
+- 4) It allows packet classification policies to be defined which refer to a desired service class, without having to refer to a particular service flow instance of that class.
+
+NOTE – The service class is optional: the flow scheduling specification may always be provided in full; a service flow may belong to no service class whatsoever. CMTS implementations MAY treat such "unclassed" flows differently from "classed" flows with equivalent parameters.
+
+Any service flow MAY have each of its QoS parameter sets specified in any of three ways:
+
+- by explicitly including all traffic parameters;
+
+- by indirectly referring to a set of traffic parameters by specifying a service class name;
+- by specifying a service class name along with modifying parameters.
+
+The service class name is "expanded" to its defined set of parameters at the time the CMTS successfully admits the service flow. The service class expansion can be contained in the following CMTS-originated messages: Registration response, DSA-REQ, DSC-REQ, DSA-RSP and DSC-RSP. In all of these cases, the CMTS MUST include a service flow encoding that includes the service class name and the QoS parameter set of the service class. If a CM-initiated request contained any supplemental or overriding service flow parameters, a successful response MUST also include these parameters.
+
+When a service class name is given in an admission or activation request, the returned QoS parameter set may change from activation to activation. This can happen because of administrative changes to the service class' QoS parameter set at the CMTS. If the definition of a service class name is changed at the CMTS (e.g., its associated QoS parameter set is modified), it has no effect on the QoS parameters of existing service flows associated with that service class. A CMTS MAY initiate DSC transactions to existing service flows that reference the service class name to affect the changed service class definition.
+
+When a CM uses the service class name to specify the admitted QoS parameter set, the expanded set of TLV encodings of the service flow will be returned to the CM in the response message (REG-RSP, DSA-RSP or DSC-RSP). Use of the service class name later in the activation request may fail if the definition of the service class name has changed and the new required resources are not available. Thus, the CM SHOULD explicitly request the expanded set of TLVs from the response message in its later activation request.
+
+#### 10.1.4 Authorization
+
+Every change to the service flow QoS parameters MUST be approved by an authorization module. This includes every REG-REQ or DSA-REQ message to create a new service flow, and every DSC-REQ message to change a QoS parameter set of an existing service flow. Such changes include requesting an admission control decision (e.g., setting the AdmittedQosParamSet) and requesting activation of a service flow (e.g., setting the ActiveQosParamSet). Reduction requests regarding the resources to be admitted or activated are also checked by the authorization module, as are requests to add or change the classifiers.
+
+In the static authorization model, the authorization module receives all registration messages and stores the provisioned status of all "deferred" service flows. Admission and activation requests for these provisioned service flows will be permitted as long as the admitted QoS parameter set is a subset of the provisioned QoS parameter set, and the active QoS parameter set is a subset of the admitted QoS parameter set. Requests to change the provisioned QoS parameter set will be refused, as will requests to create new dynamic service flows. This defines a static system where all possible services are defined in the initial configuration of each CM.
+
+In the dynamic authorization model, the authorization module not only receives all registration messages, but also communicates through a separate interface to an independent policy server. This policy server may provide to the authorization module advance notice of upcoming admission and activation requests, and specifies the proper authorization action to be taken on those requests. Admission and activation requests from a CM are then checked by the authorization module to ensure that the ActiveQosParamSet being requested is a subset of the set provided by the policy server. Admission and activation requests from a CM that are signalled in advance by the external policy server are permitted. Admission and activation requests from a CM that are not pre-signalled by the external policy server may result in a real-time query to the policy server, or may be refused.
+
+During registration, the CM MUST send to the CMTS the authenticated set of TLVs derived from its configuration file which defines the provisioned QoS parameter set. Upon receipt and
+
+verification at the CMTS, these are handed to the authorization module within the CMTS. The CMTS MUST be capable of caching the provisioned QoS parameter set, and MUST be able to use this information to authorize dynamic flows which are a subset of the provisioned QoS parameter set. The CMTS SHOULD implement mechanisms for overriding this automated approval process (such as described in the dynamic authorization model). For example:
+
+- Deny all requests whether or not they have been pre-provisioned.
+- Define an internal table with a richer policy mechanism but seeded by the configuration file information.
+- Refer all requests to an external policy server.
+
+### 10.1.5 Types of service flows
+
+It is useful to think about three basic types of service flows. This clause describes these three types of service flows in more detail. However, it is important to note that there are more than just these three basic types (refer to clause C.2.2.3.5).
+
+#### 10.1.5.1 Provisioned service flows
+
+A service flow may be provisioned but not immediately activated (sometimes called "deferred"). That is, the description of any such service flow in the TFTP configuration file contains an attribute which provisions but defers activation and admission (refer to clause C.2.2.3.5). During registration, the CMTS assigns a service flow ID for such a service flow but does not reserve resources. The CMTS MAY also require an exchange with a policy module prior to admission.
+
+As a result of external action beyond the scope of this Recommendation (e.g., [ITU-T J.162]), the CM MAY choose to activate a provisioned service flow by passing the service flow ID and the associated QoS parameter sets. The CM MUST also provide any applicable classifiers. If authorized and resources are available, the CMTS MUST respond by assigning a unique unicast SID for the upstream service flow. The CMTS MAY deactivate the service flow, but SHOULD NOT delete the service flow during the CM registration epoch.
+
+As a result of external action beyond the scope of this Recommendation (e.g., [ITU-T J.162]), the CMTS MAY choose to activate a service flow by passing the service flow ID as well as the SID and the associated QoS parameter sets. The CMTS MUST also provide any applicable classifiers. The CMTS MAY deactivate the service flow, but SHOULD NOT delete the service flow during the CM registration epoch. Such a provisioned service flow MAY be activated and deactivated many times (through DSC exchanges). In all cases, the original service flow ID MUST be used when reactivating the service flow.
+
+#### 10.1.5.2 Admitted service flows
+
+This protocol supports a two-phase activation model which is often utilized in telephony applications. In the two-phase activation model, the resources for a "call" are first "admitted," and then once the end-to-end negotiation is completed (e.g., called party's gateway generates an "off-hook" event) the resources are "activated." Such a two-phase model serves the purposes of:
+
+- a) conserving network resources until a complete end-to-end connection has been established;
+- b) performing policy checks and admission control on resources as quickly as possible, and, in particular, before informing the far end of a connection request; and
+- c) preventing several potential theft-of-service scenarios.
+
+For example, if an upper-layer service were using unsolicited grant service, and the addition of upper-layer flows could be adequately provided by increasing the grants per interval QoS parameter, then the following might be used. When the first upper-layer flow is pending, the CM issues a DSA-Request with the admit grants per interval parameter equal to one, and the activate grants per interval parameter equal to zero. Later, when the upper-layer flow becomes active, it
+
+issues a DSC-Request with the instance of the activate grants per interval parameter equal to one. Admission control was performed at the time of the reservation, so the later DSC-Request, having the activate parameters within the range of the previous reservation, is guaranteed to succeed. Subsequent upper-layer flows would be handled in the same way. If there were three upper-layer flows establishing connections, with one flow already active, the service flow would have admit(ted) grants per interval equal to four, and active grants per interval equal to one.
+
+An activation request of a service flow where the new ActiveQosParamSet is a subset of the AdmittedQosParamSet and no new classifiers are being added MUST be allowed (except in the case of catastrophic failure). An admission request where the AdmittedQosParamSet is a subset of the previous AdmittedQosParamSet, so long as the ActiveQosParamSet remains a subset of the AdmittedQosParamSet, MUST succeed.
+
+A service flow that has resources assigned to its AdmittedQosParamSet, but whose resources are not yet completely activated, is in a transient state. A timeout value MUST be enforced by the CMTS that requires service flow activation within this period (refer to clause C.2.2.5.7). If service flow activation is not completed within this interval, the assigned resources in excess of the active QoS parameters MUST be released by the CMTS.
+
+It is possible in some applications that a long-term reservation of resources is necessary or desirable. For example, placing a telephone call on hold should allow any resources in use for the call to be temporarily allocated to other purposes, but these resources must be available for resumption of the call later. The AdmittedQosParamSet is maintained as "soft state" in the CMTS; this state must be refreshed periodically for it to be maintained without the above timeout releasing the non-activated resources. This refresh MAY be signalled with a periodic DSC-REQ message with identical QoS parameter sets, or MAY be signalled by some internal mechanism within the CMTS outside of the scope of this Recommendation (e.g., by the CMTS monitoring RSVP refresh messages). Every time a refresh is signalled to the CMTS, the CMTS MUST refresh the "soft state."
+
+### 10.1.5.3 Active service flows
+
+A service flow that has a non-NULL set of ActiveQosParameters is said to be an active service flow. It is requesting<sup>24</sup> and being granted bandwidth for transport of data packets. An admitted service flow may be made active by providing an ActiveQosParamSet, signalling the resources actually desired at the current time. This completes the second stage of the two-phase activation model (refer to clause 10.1.5.2).
+
+A service flow may be provisioned and immediately activated. This is the case for the primary service flows. It is also typical of service flows for monthly subscription services, etc. These service flows are established at registration time and MUST be authorized by the CMTS based on the CMTS MIC. These service flows MAY also be authorized by the CMTS authorization module.
+
+Alternatively, a service flow may be created dynamically and immediately activated. In this case, two-phase activation is skipped and the service flow is available for immediate use upon authorization.
+
+### 10.1.6 Service flows and classifiers
+
+The basic model is that the classifiers associate packets into exactly one service flow. The service flow encodings provide the QoS parameters for treatment of those packets on the RF interface. These encodings are described in clause C.2.
+
+In the upstream direction, the CM MUST classify upstream packets to active service flows. The CMTS MUST classify downstream traffic to active downstream service flows. There MUST be a default downstream service flow for otherwise unclassified broadcast and multicast traffic.
+
+---
+
+<sup>24</sup> According to its request/transmission policy (refer to clause C.2.2.6.3).
+
+The CMTS polices packets in upstream service flows to ensure the integrity of the QoS parameters and the packet's ToS value. When the rate at which packets are sent is greater than the policed rate at the CMTS, then these packets MAY be dropped by the CMTS (refer to clause C.2.2.5.2). When the value of the ToS byte is incorrect, the CMTS (based on policy) MUST police the stream by overwriting the ToS byte (refer to clause C.2.2.6.10).
+
+It may not be possible for the CM to forward certain upstream packets on certain service flows. In particular, a service flow using unsolicited grant service with fragmentation disabled cannot be used to forward packets larger than the grant size. If a packet is classified to a service flow on which it cannot be transmitted, the CM MUST either transmit the packet on the primary service flow or discard the packet depending on the request/transmission policy of the service flow to which the packet was classified.
+
+MAC management messages may only be matched by a classifier that contains a clause C.2.1.6.3 "ethertype/DSAP/MacType" parameter encoding and when the "type" field of the MAC management message header (see clause 8.3.1) matches that parameter. One exception is that the primary SID MUST be used for periodic ranging, as specified in clause 8.1.2.3, even if a classifier matches the upstream RNG-REQ message of periodic ranging. In the absence of any classifier matching a MAC management message, it SHOULD be transmitted on the primary service flow. Other than those MAC message types precluded from classification in clause C.2.1.6.3, a CM or CMTS MAY forward an otherwise unclassified MAC message on any service flow in an implementation-specific manner.
+
+Although MAC management messages are subject to classification, they are not considered part of any service flow. Transmission of MAC management messages MUST NOT influence any QoS calculations of the service flow to which they are classified. Delivery of MAC management messages is implicitly influenced by the attributes of the associated service flow.
+
+#### 10.1.6.1 Policy-based classification and service classes
+
+As noted in Appendix I, there are a variety of ways in which packets may be enqueued for transmission at the MAC service interface. At one extreme are embedded applications that are tightly bound to a particular payload header suppression rule (refer to clause 10.4) and which forego more general classification by the MAC. At the other extreme are general transit packets of which nothing is known until they are parsed by the MAC classification rules. Another useful category is traffic to which policies are applied by a higher-layer entity and then passed to the MAC for further classification to a particular service flow.
+
+Policy-based classification is, in general, beyond the scope of this Recommendation. One example might be the docsDevFilterIpPolicyTable defined in the Cable Device MIB [b-RFC 2669]. Such policies may tend to be longer-lived than individual service flows and MAC classifiers and so it is appropriate to layer the two mechanisms, with a well-defined interface between policies and MAC service flow classification.
+
+The interface between the two layers is the addition of two parameters at the MAC transmission request interface. The two parameters are a service class name and a rule priority that is applied to matching the service class name. The policy priority is from the same number space as the packet classifier priority of the packet-matching rules used by MAC classifiers. The MAC classification algorithm is now:
+
+```
+MAC_DATA.request( PDU, ServiceClassName, RulePriority )
+TxServiceFlowID = FIND_FIRST_SERVICE_FLOW_ID (ServiceClassName)
+SearchID = SEARCH_CLASSIFIER_TABLE (All Priority Levels)
+IF (SearchID not NULL and Classifier.RulePriority >= MAC_DATA.RulePriority)
+    TxServiceFlowID = SearchID
+IF (TxServiceFlowID = NULL)
+    TRANSMIT_PDU (PrimaryServiceFlowID)
+```
+
+ELSE
+
+TRANSMIT\_PDU (TxServiceFlowID)
+
+While policy priority competes with packet classifier priority and its choice might in theory be problematic, it is anticipated that well-known ranges of priorities will be chosen to avoid ambiguity. In particular, dynamically-added classifiers **MUST** use the priority range 64-191. Classifiers created as part of registration, as well as policy-based classifiers, may use zero through 255, but **SHOULD** avoid the dynamic range.
+
+NOTE – Classification within the MAC sublayer is intended to simply associate a packet with a service flow. If a packet is intended to be dropped it **MUST** be dropped by the higher-layer entity and not delivered to the MAC sublayer.
+
+### 10.1.7 General operation
+
+#### 10.1.7.1 Static operation
+
+Static configuration of classifiers and service flows uses the registration process. A provisioning server provides the CM with configuration information. The CM passes this information to the CMTS in a registration request. The CMTS adds information and replies with a registration response. The CM sends a registration acknowledge to complete registration.
+
+![Sequence diagram showing the registration message flow between a CM, a Provisioning Server, and a CMTS.](8d6b5c2a30f8346755d79f2150c3177b_img.jpg)
+
+```
+sequenceDiagram
+    participant CM
+    participant PS as Provisioning Server
+    participant CMTS
+    Note left of CM: J.122_F10-5
+    PS->>CM: TFTP Configuration
+    CM->>CMTS: Registration Request
+    CMTS->>CM: Registration Response
+    CM->>CMTS: Registration Acknowledge
+```
+
+The diagram illustrates the registration message flow. It features three vertical lifelines: CM (Client Module), Provisioning Server, and CMTS (Cable Modem Termination System). The sequence of messages is as follows: 1. TFTP Configuration: A message from the Provisioning Server to the CM. 2. Registration Request: A message from the CM to the CMTS. 3. Registration Response: A message from the CMTS to the CM. 4. Registration Acknowledge: A message from the CM to the CMTS. The diagram is labeled 'J.122\_F10-5' at the bottom right.
+
+Sequence diagram showing the registration message flow between a CM, a Provisioning Server, and a CMTS.
+
+**Figure 10-5 – Registration message flow**
+
+A TFTP configuration file consists of one or more instances of classifiers and service flow encodings. Classifiers are loosely ordered by 'priority'. Each classifier refers to a service flow via a 'service flow reference'. Several classifiers may refer to the same service flow. Additionally, more than one classifier may have the same priority, and in this case, the particular classifier used is not defined.
+
+**Table 10-1 – TFTP file contents**
+
+| Items                                                                                   | Point to service flow reference | Service flow reference | Service flow ID |
+|-----------------------------------------------------------------------------------------|---------------------------------|------------------------|-----------------|
+| <b>Upstream classifiers</b><br>Each containing a service flow reference (pointer)       | 1..n                            |                        |                 |
+| <b>Downstream classifiers</b><br>Each containing a service flow reference (pointer)     | (n + 1)..q                      |                        |                 |
+| <b>Service flow encodings</b><br>Immediate activation requested, upstream               |                                 | 1..m                   | None yet        |
+| <b>Service flow encodings</b><br>Provisioned for later activation requested, upstream   |                                 | (m + 1)..n             | None yet        |
+| <b>Service flow encodings</b><br>Immediate activation requested, downstream             |                                 | (n + 1)..p             | None yet        |
+| <b>Service flow encodings</b><br>Provisioned for later activation requested, downstream |                                 | (p + 1)..q             | None yet        |
+
+Service flow encodings contain either a full definition of service attributes (omitting defaultable items if desired) or a service class name. A service class name is an ASCII string which is known at the CMTS and which indirectly specifies a set of QoS parameters (refer to clauses 10.1.3 and C.2.2.3.4)
+
+NOTE – At the time of the TFTP configuration file, service flow references exist as defined by the provisioning server. Service flow identifiers do not yet exist because the CMTS is unaware of these service flow definitions.
+
+The registration request packet contains downstream classifiers (if to be immediately activated) and all inactive service flows. The configuration file, and thus the registration request, generally does not contain a downstream classifier if the corresponding service flow is requested with deferred activation. This allows for late binding of the classifier when the flow is activated.
+
+**Table 10-2 – Registration request contents**
+
+| Items                                                                                                                                | Point to service flow reference | Service flow reference | Service flow ID |
+|--------------------------------------------------------------------------------------------------------------------------------------|---------------------------------|------------------------|-----------------|
+| <b>Upstream classifiers</b><br>Each containing a service flow reference (pointer)                                                    | 1..n                            |                        |                 |
+| <b>Downstream classifiers</b><br>Each containing a service flow reference (pointer)                                                  | (n + 1)..p                      |                        |                 |
+| <b>Service flow encodings</b><br>Immediate activation requested, upstream.<br>May specify explicit attributes or service class name. |                                 | 1..m                   | None yet        |
+| <b>Service flow encodings</b><br>Provisioned for later activation requested, upstream.<br>Explicit attributes or service class name. |                                 | (m + 1)..n             | None yet        |
+| <b>Service flow encodings</b><br>Immediate activation requested, downstream.<br>Explicit attributes or service name.                 |                                 | (n + 1)..p             | None yet        |
+| <b>Service flow encodings</b><br>Provisioned for later activation requested, downstream.<br>Explicit attributes or service name.     |                                 | (p + 1)..q             | None yet        |
+
+The registration response sets the QoS parameter sets according to the quality of service parameter set type in the registration request.
+
+The registration response preserves the service flow reference attribute, so that the service flow reference can be associated with SFID and/or SID.
+
+**Table 10-3 – Registration response contents**
+
+| Items                                                    | Service flow reference | Service flow identifier | Service identifier |
+|----------------------------------------------------------|------------------------|-------------------------|--------------------|
+| Active upstream service flows explicit attributes        | 1..m                   | SFID                    | SID                |
+| Provisioned upstream service flows explicit attributes   | (m + 1)..n             | SFID                    | Not yet            |
+| Active downstream service flows explicit attributes      | (n + 1)..p             | SFID                    | N/A                |
+| Provisioned downstream service flows explicit attributes | (p + 1)..q             | SFID                    | N/A                |
+
+The SFID is chosen by the CMTS to identify a downstream or upstream service flow that has been authorized but not activated. A DSC-Request from a modem to admit or activate a provisioned service flow contains its SFID. If it is a downstream flow then the downstream classifier is also included.
+
+### 10.1.7.2 Dynamic service flow Creation – CM-initiated
+
+Service flows may be created by the dynamic service addition process, as well as through the registration process outlined above. The dynamic service addition may be initiated by either the CM or the CMTS, and may create one upstream and/or one downstream dynamic service flow(s). A three-way handshake is used to create service flows. The CM-initiated protocol is illustrated in Figure 10-6 and described in detail in clause 11.4.2.1.
+
+![Sequence diagram for CM-initiated dynamic service addition. A Client Module (CM) sends a DSA-Request to a Cable Modem Termination System (CMTS). The CMTS responds with a DSA-Response, and the CM replies with a DSA-Acknowledge. The diagram is labeled J.122_F10-6.](c07637986c84860270f00b7af39e1956_img.jpg)
+
+```
+
+sequenceDiagram
+    participant CM
+    participant CMTS
+    CM->>CMTS: DSA-Request
+    CMTS-->>CM: DSA-Response
+    CM->>CMTS: DSA-Acknowledge
+  
+```
+
+Sequence diagram for CM-initiated dynamic service addition. A Client Module (CM) sends a DSA-Request to a Cable Modem Termination System (CMTS). The CMTS responds with a DSA-Response, and the CM replies with a DSA-Acknowledge. The diagram is labeled J.122\_F10-6.
+
+**Figure 10-6 – Dynamic service addition message flow – CM-initiated**
+
+A DSA-Request from a CM contains service flow reference(s), QoS parameter set(s) (marked either for admission-only or for admission and activation) and any required classifiers.
+
+### 10.1.7.3 Dynamic service flow creation – CMTS-initiated
+
+A DSA-Request from a CMTS contains service flow identifier(s) for one upstream and/or one downstream service flow, possibly a SID, set(s) of active or admitted QoS parameters, and any required classifier(s). The protocol is as illustrated in Figure 10-7 and is described in detail in clause 11.4.2.2.
+
+![Sequence diagram for CMTS-initiated dynamic service addition. A Cable Modem Termination System (CMTS) sends a DSA-Request to a Client Module (CM). The CM responds with a DSA-Response, and the CMTS replies with a DSA-Acknowledge. The diagram is labeled J.122_F10-7.](d4369a53cb56f10f74fbed39280e9245_img.jpg)
+
+```
+
+sequenceDiagram
+    participant CMTS
+    participant CM
+    CMTS->>CM: DSA-Request
+    CM-->>CMTS: DSA-Response
+    CMTS->>CM: DSA-Acknowledge
+  
+```
+
+Sequence diagram for CMTS-initiated dynamic service addition. A Cable Modem Termination System (CMTS) sends a DSA-Request to a Client Module (CM). The CM responds with a DSA-Response, and the CMTS replies with a DSA-Acknowledge. The diagram is labeled J.122\_F10-7.
+
+**Figure 10-7 – Dynamic service addition message flow – CMTS-initiated**
+
+### 10.1.7.4 Dynamic service flow modification and deletion
+
+In addition to the methods presented above for creating service flows, protocols are defined for modifying and deleting service flows. Refer to clauses 11.4.3 and 11.4.4.
+
+Both provisioned and dynamically created service flows are modified with the DSC message, which can change the admitted and active QoS parameter sets of the flow. The DSC can also add, replace, or delete classifiers, and add, add parameters to, or delete PHS Rules.
+
+A successful DSC transaction changes a service flow's QoS parameters by replacing both the admitted and active QoS parameter sets. If the message contains only the admitted set, the active set is set to null and the flow is deactivated. If the message contains neither set ('000' value used for quality of service parameter set type, see clause C.2.2.3.5) then both sets are set to null and the flow is de-admitted. When the message contains both QoS parameter sets, the admitted set is checked first and, if admission control succeeds, the active set in the message is checked against the admitted set in the message to ensure that it is a subset (see clause 10.1.1.1). If all checks are successful, the QoS parameter sets in the message become the new admitted and active QoS
+
+parameter sets for the service flow. If either of the checks fails, the DSC transaction fails and the service flow QoS parameter sets are unchanged.
+
+## 10.2 Upstream service flow scheduling services
+
+The following clauses define the basic upstream service flow scheduling services and list the QoS parameters associated with each service. A detailed description of each QoS parameter is provided in Annex C. Annex C also discusses how these basic services and QoS parameters can be combined to form new services, such as committed information rate (CIR) service.
+
+Scheduling services are designed to improve the efficiency of the poll/grant process. By specifying a scheduling service and its associated QoS parameters, the CMTS can anticipate the throughput and latency needs of the upstream traffic and provide polls and/or grants at the appropriate times.
+
+Each service is tailored to a specific type of data flow as described below. The basic services comprise: unsolicited grant service (UGS), real-time polling service (rtPS), unsolicited grant service with activity detection (UGS-AD), non-real-time polling service (nrtPS) and best effort (BE) service. Table 10-4 shows the relationship between the scheduling services and the related QoS parameters.
+
+### 10.2.1 Unsolicited grant service
+
+The unsolicited grant service (UGS) is designed to support real-time service flows that generate fixed size data packets on a periodic basis, such as voice over IP. The service offers fixed-size grants on a real-time periodic basis, which eliminate the overhead and latency of CM requests and assure that grants will be available to meet the flow's real-time needs. The CMTS MUST provide fixed-size data grants at periodic intervals to the service flow. In order for this service to work correctly, the request/transmission policy (refer to clause C.2.2.6.3) setting MUST be such that the CM is prohibited from using any contention request or request/data opportunities and the CMTS SHOULD NOT provide any unicast request opportunities. The request/transmission policy MUST also prohibit piggyback requests. This will result in the CM only using unsolicited data grants for upstream transmission. All other bits of the request/transmission policy are not relevant to the fundamental operation of this scheduling service and should be set according to network policy. The key service parameters are the unsolicited grant size, the nominal grant interval, the tolerated grant jitter and the request/transmission policy (refer to Appendix VI).
+
+The unsolicited grant synchronization header (UGSH) in the service flow EH element (refer to clause 8.2.6.3.2) is used to pass status information from the CM to the CMTS regarding the state of the UGS service flow. The most significant bit of the UGSH is the queue indicator (QI) flag. When the QI flag is set, it indicates a rate overrun condition for the service flow. When the QI flag is clear, it indicates a rate non-overrun condition for the service flow. The QI flag allows the CMTS to provide for a dynamic rate compensation function by issuing additional grants.
+
+The CM MUST set the QI flag when it detects that the packet reception rate is greater than the upstream transmission rate. The CM MUST clear the QI flag when it detects that the packet reception rate is equal to or less than the upstream transmission rate and the queued packet backlog is cleared.
+
+The number of packets already queued for upstream transmission is a measure of the rate differential between received and transmitted packets. The CM SHOULD set the QI flag when the number of packets queued is greater than the number of grants per interval parameter of the active QoS set. The CM SHOULD clear the QI flag when the number of packets queued is less than or equal to the number of grants per interval parameter of the active QoS set. The QI flag of each packet MAY be set either at the time the packet is received and queued or at the time the packet is dequeued and transmitted.
+
+The CM MAY set/clear the QI flag using a threshold of two times the number of grants per interval parameter of the active QoS set. Alternatively, the CM MAY provide hysteresis by setting the QI flag using a threshold of two times the number of grants per interval, then clearing it using a threshold of one times the number of grants per interval.
+
+The CMTS MUST NOT allocate more grants per nominal grant interval than the grants per interval parameter of the active QoS parameter set, excluding the case when the QI bit of the UGSH is set. In this case, the CMTS SHOULD grant up to 1% additional bandwidth for clock rate mismatch compensation. If the CMTS grants additional bandwidth, it MUST limit the total number of bytes forwarded on the flow during any time interval to  $\text{Max}(T)$ , as described in the expression:
+
+$$\text{Max}(T) = T \times (R \times 1.01) + 3B$$
+
+where:
+
+$\text{Max}(T)$  = the maximum number of bytes transmitted on the flow over a time  $T$  (in units of seconds)
+
+$R$  =  $(\text{grant\_size} \times \text{grants\_per\_interval}) / \text{nominal\_grant\_interval}$
+
+$B$  =  $\text{grant\_size} \times \text{grants\_per\_interval}$
+
+The active grants field of the UGSH is ignored with UGS service. The CMTS policing of the service flow remains unchanged.
+
+### 10.2.2 Real-time polling service
+
+The real-time polling service (rtPS) is designed to support real-time service flows that generate variable-size data packets on a periodic basis, such as MPEG video. The service offers real-time, periodic, unicast request opportunities, which meet the flow's real-time needs and allow the CM to specify the size of the desired grant. This service requires more request overhead than UGS, but supports variable grant sizes for optimum data transport efficiency.
+
+The CMTS MUST provide periodic unicast request opportunities. In order for this service to work correctly, the request/transmission policy setting (refer to clause C.2.2.6.3) SHOULD be such that the CM is prohibited from using any contention request or request/data opportunities. The request/transmission policy SHOULD also prohibit piggyback requests. The CMTS MAY issue unicast request opportunities as prescribed by this service even if a grant is pending. This will result in the CM using only unicast request opportunities in order to obtain upstream transmission opportunities (the CM could still use unsolicited data grants for upstream transmission as well). All other bits of the request/transmission policy are not relevant to the fundamental operation of this scheduling service and should be set according to network policy. The key service parameters are the nominal polling interval, the tolerated poll jitter and the request/transmission policy.
+
+### 10.2.3 Unsolicited grant service with activity detection
+
+The unsolicited grant service with activity detection (UGS-AD) is designed to support UGS flows that may become inactive for substantial portions of time (i.e., tens of milliseconds or more), such as voice over IP with silence suppression. The service provides unsolicited grants when the flow is active and unicast polls when the flow is inactive. This combines the low overhead and low latency of UGS with the efficiency of rtPS. Though USG/AD combines UGS and rtPS, only one scheduling service is active at a time.
+
+The CMTS MUST provide periodic unicast grants when the flow is active but MUST revert to providing periodic unicast request opportunities when the flow is inactive. (The CMTS can detect flow inactivity by detecting unused grants. However, the algorithm for detecting a flow changing from an active to an inactive state is dependent on the CMTS implementation.) In order for this service to work correctly, the request/transmission policy setting (refer to clause C.2.2.6.3) MUST be such that the CM is prohibited from using any contention request or request/data opportunities. The request/transmission policy MUST also prohibit piggyback requests. This results in the CM
+
+using only unicast request opportunities in order to obtain upstream transmission opportunities. However, the CM will use unsolicited data grants for upstream transmission as well. All other bits of the request/transmission policy are not relevant to the fundamental operation of this scheduling service and should be set according to network policy. The key service parameters are the nominal polling interval, the tolerated poll jitter, the nominal grant interval, the tolerated grant jitter, the unsolicited grant size and the request/transmission policy.
+
+In UGS-AD service, when restarting UGS after an interval of rtPS, the CMTS SHOULD provide additional grants in the first (and/or second) grant interval such that the CM receives a total of one grant for each grant interval from the time the CM requested restart of UGS, plus one additional grant (refer to Appendix VI). Because the service flow is provisioned as a UGS flow with a specific grant interval and grant size, when restarting UGS, the CM MUST NOT request a different sized grant than the already provisioned UGS flow. As with any service flow, changes can only be requested with a DSC command. If the restarted activity requires more than one grant per interval, the CM MUST indicate this in the active grants field of the UGSH beginning with the first packet sent.
+
+The service flow extended header element allows for the CM to dynamically state how many grants per interval are required to support the number of flows with activity present. In UGS-AD, the CM MAY use the queue indicator bit in the UGSH. The remaining seven bits of the UGSH define the active grants field. This field defines the number of grants within a nominal grant interval that this service flow currently requires. When using UGS-AD, the CM MUST indicate the number of requested grants per nominal grant interval in this field. The active grants field of the UGSH is ignored with UGS without activity detection. This field allows the CM to signal to the CMTS to dynamically adjust the number of grants per interval that this UGS service flow is actually using. The CM MUST NOT request more than the number of grants per interval in the ActiveQosParamSet.
+
+If the CMTS allocates additional bandwidth in response to the QI bit, it MUST use the same rate-limiting formula as UGS, but the formula only applies to steady state periods where the CMTS has adjusted the grants\_per\_interval to match the active\_grants requested by the CM.
+
+When the CM is receiving unsolicited grants and it detects no activity on the service flow, it MAY send one packet with the active grants field set to zero grants and then cease transmission. Because this packet may not be received by the CMTS, when the service flow goes from inactive to active the CM MUST be able to restart transmission with either polled requests or unsolicited grants.
+
+#### **10.2.4 Non-real-time polling service**
+
+The non-real-time polling service (nrtPS) is designed to support non real-time service flows that require variable size data grants on a regular basis, such as high bandwidth FTP. The service offers unicast polls on a regular basis, which assures that the flow receives request opportunities even during network congestion. The CMTS typically polls nrtPS SIDs on an (periodic or non-periodic) interval on the order of one second or less.
+
+The CMTS MUST provide timely unicast request opportunities. In order for this service to work correctly, the request/transmission policy setting (refer to clause C.2.2.6.3) SHOULD be such that the CM is allowed to use contention request opportunities. This will result in the CM using contention request opportunities as well as unicast request opportunities and unsolicited data grants. All other bits of the request/transmission policy are not relevant to the fundamental operation of this scheduling service and should be set according to network policy. The key service parameters are nominal polling interval, minimum reserved traffic rate, maximum sustained traffic rate, request/transmission policy and traffic priority.
+
+### 10.2.5 Best effort service
+
+The intent of the best effort (BE) service is to provide efficient service to best effort traffic. In order for this service to work correctly, the request/transmission policy setting SHOULD be such that the CM is allowed to use contention request opportunities. This will result in the CM using contention request opportunities as well as unicast request opportunities and unsolicited data grants. All other bits of the request/transmission policy are not relevant to the fundamental operation of this scheduling service and should be set according to network policy. The key service parameters are the minimum reserved traffic rate, the maximum sustained traffic rate, and the traffic priority.
+
+### 10.2.6 Other services
+
+#### 10.2.6.1 Committed information rate (CIR)
+
+A committed information rate (CIR) service can be defined a number of different ways. For example, it could be configured by using a best effort service with a minimum reserved traffic rate or a nrtPS with a minimum reserved traffic rate.
+
+### 10.2.7 Parameter applicability for upstream service scheduling
+
+Table 10-4 summarizes the relationship between the scheduling services and key QoS parameters. A detailed description of each QoS parameter is provided in Annex C.
+
+**Table 10-4 – Parameter applicability for upstream service scheduling**
+
+| Service flow parameter             | Best effort              | Non-real-time polling   | Real-time polling       | Unsolicited grant      | Unsolicited grant with activity detection |
+|------------------------------------|--------------------------|-------------------------|-------------------------|------------------------|-------------------------------------------|
+| <b>Miscellaneous</b>               |                          |                         |                         |                        |                                           |
+| • Traffic priority                 | Optional, default = 0    | Optional default = 0    | N/A <sup>a)</sup>       | N/A                    | N/A                                       |
+| • Max. concatenated burst          | Optional                 | Optional                | Optional                | N/A                    | N/A                                       |
+| • Upstream scheduling service type | Optional, default = 2    | Mandatory               | Mandatory               | Mandatory              | Mandatory                                 |
+| • Request/transmission policy      | Optional, default = 0    | Mandatory               | Mandatory               | Mandatory              | Mandatory                                 |
+| <b>Maximum rate</b>                |                          |                         |                         |                        |                                           |
+| • Max. sustained traffic rate      | Optional, default = 0    | Optional default = 0    | Optional default = 0    | N/A                    | N/A                                       |
+| • Max. traffic burst               | Optional, default = 1522 | Optional default = 1522 | Optional default = 1522 | N/A                    | N/A                                       |
+| <b>Minimum rate</b>                |                          |                         |                         |                        |                                           |
+| • Min. reserved traffic rate       | Optional, default = 0    | Optional default = 0    | Optional default = 0    | N/A                    | N/A                                       |
+| • Assumed minimum packet size      | Optional <sup>c)</sup>   | Optional <sup>c)</sup>  | Optional <sup>c)</sup>  | Optional <sup>c)</sup> | Optional <sup>c)</sup>                    |
+| <b>Grants</b>                      |                          |                         |                         |                        |                                           |
+| • Unsolicited grant size           | N/A                      | N/A                     | N/A                     | Mandatory              | Mandatory                                 |
+| • Grants per interval              | N/A                      | N/A                     | N/A                     | Mandatory              | Mandatory                                 |
+| • Nominal grant interval           | N/A                      | N/A                     | N/A                     | Mandatory              | Mandatory                                 |
+
+**Table 10-4 – Parameter applicability for upstream service scheduling**
+
+| Service flow parameter                                                                                                                                                                                                                                                                             | Best effort | Non-real-time polling   | Real-time polling       | Unsolicited grant | Unsolicited grant with activity detection |
+|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------|-------------------------|-------------------------|-------------------|-------------------------------------------|
+| • Tolerated grant jitter                                                                                                                                                                                                                                                                           | N/A         | N/A                     | N/A                     | Mandatory         | Mandatory                                 |
+| <b>Polls</b>                                                                                                                                                                                                                                                                                       |             |                         |                         |                   |                                           |
+| • Nominal polling interval                                                                                                                                                                                                                                                                         | N/A         | Optional <sup>(c)</sup> | Mandatory               | N/A               | Optional <sup>b)</sup>                    |
+| • Tolerated poll jitter                                                                                                                                                                                                                                                                            | N/A         | N/A                     | Optional <sup>(c)</sup> | N/A               | Optional <sup>(c)</sup>                   |
+| <sup>a)</sup> N/A means not applicable to this service flow scheduling type. If included in a request for a service flow of this service flow scheduling type, this request MUST be denied.<br><sup>b)</sup> Default is same as nominal grant interval.<br><sup>c)</sup> Default is CMTS-specific. |             |                         |                         |                   |                                           |
+
+### 10.2.8 CM transmit behaviour
+
+In order for these services to function correctly, all that is required of the CM in regards to its transmit behaviour for a service flow is for it to follow the rules specified in clause 9.4.3 and the request/transmission policy specified for the service flow.
+
+## 10.3 Fragmentation
+
+Fragmentation is an upstream CM "modem capability". The CMTS MUST enable or disable this capability on a per-modem basis with a TLV in the registration response. The per-modem basis provides compatibility with DOCS 1.0 CMs. Once fragmentation is enabled for a DOCS 1.1 modem, fragmentation is enabled on a per-service flow basis via the request/transmission policy configuration settings. When enabled for a service flow, fragmentation is initiated by the CMTS when it grants bandwidth to a particular CM with a grant size that is smaller than the corresponding bandwidth request from the CM. This is known as a **partial grant**.
+
+### 10.3.1 CM fragmentation support
+
+Fragmentation is essentially encapsulation of a portion of a MAC frame within a fixed size fragmentation header and a fragment CRC. Concatenated PDUs, as well as single PDUs, are encapsulated in the same manner. Baseline privacy, if enabled, is performed on each fragment as opposed to the complete original MAC frame.
+
+The CM MUST perform fragmentation according to the flow diagram in Figure 10-8. The phrase "untransmitted portion of packet" in the flow diagram refers to the entire MAC frame when fragmentation has not been initiated, and to the remaining untransmitted portion of the original MAC frame when fragmentation has been initiated.
+
+![Flowchart for CM fragmentation process. It starts with 'Start', followed by 'Await frame arrival', 'Request Bandwidth for SIDx', and 'Process MAP information elements'. The main decision loop checks 'Grant for SIDx?'. If 'Yes', it checks 'Grant smaller than request or request remainder?'. If 'Yes', it checks 'Fragmentation allowed for this SID?'. If 'Yes', it calculates fragmentation amount and checks 'Another grant or grant pending in MAP queue?'. Depending on the answer, it sends a fragment with zero or the request remainder in the piggyback field. If 'No' at any point, it checks 'Another frame in queue?'. If 'Yes', it sends the untransmitted portion with a request for the next frame. If 'No', it sends the untransmitted portion with piggyback field(s)=0. If 'No' to 'Grant for SIDx?', it checks 'Grant pending?'. If 'Yes', it goes to 'Backoff and re-request for untransmitted portion of frame'. If 'No', it checks 'Ack timer expired?'. If 'Yes', it checks 'Retries exhausted?'. If 'Yes', it discards the untransmitted portion. If 'No', it goes to 'Backoff and re-request for untransmitted portion of frame'. If 'No' to 'Ack timer expired?', it goes to 'Backoff and re-request for untransmitted portion of frame'.](f117583d264d1fa4b9c67c44879bb3e7_img.jpg)
+
+```
+
+graph TD
+    Start([Start]) --> Await[Await frame arrival]
+    Await --> Request[Request Bandwidth for SIDx]
+    Request --> Process[Process MAP information elements]
+    Process --> GrantForSIDx{Grant for SIDx?}
+    GrantForSIDx -- No --> GrantPending{Grant pending?}
+    GrantPending -- Yes --> Backoff[Backoff and re-request for untransmitted portion of frame]
+    GrantPending -- No --> AckTimer{Ack timer expired?}
+    AckTimer -- Yes --> RetriesExhausted{Retries exhausted?}
+    RetriesExhausted -- Yes --> Discard1[Discard untransmitted portion of frame]
+    RetriesExhausted -- No --> Backoff
+    AckTimer -- No --> Backoff
+    Backoff --> Request
+    GrantForSIDx -- Yes --> GrantSmaller{Grant smaller than request or request remainder?}
+    GrantSmaller -- Yes --> FragmentationAllowed{Fragmentation allowed for this SID?}
+    FragmentationAllowed -- Yes --> CalcFragment[Calculate amount to fragment and bandwidth needed to transmit remainder (request remainder)]
+    CalcFragment --> AnotherGrant{Another grant or grant pending in MAP queue?}
+    AnotherGrant -- Yes --> SendFragmentZero[Send fragment with zero in the piggyback field]
+    AnotherGrant -- No --> SendFragmentRemainder[Send fragment with piggyback field set to request remainder]
+    FragmentationAllowed -- No --> DiscardGrant[Discard grant or send up request in granted slot]
+    GrantSmaller -- No --> AnotherFrame{Another frame in queue?}
+    AnotherFrame -- Yes --> SendUntransmittedNext[Send untransmitted portion of frame with request for next frame in piggyback field]
+    AnotherFrame -- No --> SendUntransmittedZero[Send untransmitted portion of frame with piggyback field(s)=0.]
+    SendFragmentZero --> Request
+    SendFragmentRemainder --> Request
+    DiscardGrant --> Request
+    SendUntransmittedNext --> Request
+    SendUntransmittedZero --> Request
+    Discard1 --> Request
+  
+```
+
+Flowchart for CM fragmentation process. It starts with 'Start', followed by 'Await frame arrival', 'Request Bandwidth for SIDx', and 'Process MAP information elements'. The main decision loop checks 'Grant for SIDx?'. If 'Yes', it checks 'Grant smaller than request or request remainder?'. If 'Yes', it checks 'Fragmentation allowed for this SID?'. If 'Yes', it calculates fragmentation amount and checks 'Another grant or grant pending in MAP queue?'. Depending on the answer, it sends a fragment with zero or the request remainder in the piggyback field. If 'No' at any point, it checks 'Another frame in queue?'. If 'Yes', it sends the untransmitted portion with a request for the next frame. If 'No', it sends the untransmitted portion with piggyback field(s)=0. If 'No' to 'Grant for SIDx?', it checks 'Grant pending?'. If 'Yes', it goes to 'Backoff and re-request for untransmitted portion of frame'. If 'No', it checks 'Ack timer expired?'. If 'Yes', it checks 'Retries exhausted?'. If 'Yes', it discards the untransmitted portion. If 'No', it goes to 'Backoff and re-request for untransmitted portion of frame'. If 'No' to 'Ack timer expired?', it goes to 'Backoff and re-request for untransmitted portion of frame'.
+
+J.122\_F.10-8
+
+Figure 10-8 – CM fragmentation flowchart
+
+### 10.3.1.1 Fragmentation rules
+
+- 1) Any time fragmentation is enabled and the grant size is smaller than the request, the CM MUST fill the partial grant it receives with the maximum amount of data (fragment payload) possible accounting for fragmentation overhead and physical layer overhead.
+- 2) The CM MUST send up a piggyback request any time there is no later grant or grant pending for that SID in MAPs that have been received at the CM.
+- 3) If the CM is fragmenting a frame<sup>25</sup>, any piggyback request for the next fragment MUST be made in the BPI EHDR portion of the fragment header. Any piggyback request for a subsequent frame SHOULD be made in the BPI EHDR portion of the last fragment, but MAY be made in one of the extended headers inside the original frame. However, the same request MUST NOT be made in more than one place. Because the CMTS could ignore a request inside the original frame, making the request in the original frame may cause a loss of the request.
+- 4) In calculating bandwidth requests for the remainder of the frame (concatenated frame, if concatenated) that has been fragmented, the CM MUST request enough bandwidth to transmit the entire remainder of the frame plus the 16-byte fragment overhead and all associated physical layer overhead.
+- 5) If the CM does not receive a grant or grant pending within the ack time of sending a request, the CM MUST backoff and re-request for the untransmitted portion of the frame until the bandwidth is granted or the CM exceeds its retry threshold.
+- 6) If the CM exceeds its retry threshold while requesting bandwidth, the CM discards whatever portion of the frame was not previously transmitted.
+- 7) The CM MUST set the F bit and clear the L bit in the first fragment of a frame.
+- 8) The CM MUST clear the F and L bits in the fragment header for any fragments that occur between the first and last fragments of a frame.
+- 9) The CM MUST set the L bit and clear the F bit in the last fragment of a frame.
+- 10) The CM MUST increment the fragment sequence number sequentially for each fragment of a frame transmitted.
+- 11) If a frame is to be encrypted and the frame is fragmented, the frame is encrypted only at the fragment layer with encryption beginning immediately after the fragment header HCS and continuing through the fragment CRC.
+- 12) Frames sent in immediate data (request/data) regions MUST NOT be fragmented.
+
+### 10.3.2 CMTS fragmentation support
+
+At the CMTS, the fragment is processed similarly to an ordinary packet with the exception that the baseline privacy encryption starts just after the fragmentation header as opposed to being offset by 12 bytes.
+
+The CMTS has two modes it can use to perform fragmentation. The multiple grant mode assumes that the CMTS retains the state of the fragmentation. This mode allows the CMTS to have multiple partial grants outstanding for any given SID. The piggyback mode assumes the CMTS does NOT retain any fragmentation state. Only one partial grant is outstanding, so that the CM inserts the remaining amount into the piggyback field of the fragment header. The type of mode being used is determined by the CMTS. In all cases, the CM operates with a consistent set of rules.
+
+---
+
+<sup>25</sup> 'Frame' always refers to either frames with a single packet PDU or concatenated frames.
+
+### 10.3.2.1 Multiple grant mode
+
+A CMTS MUST support multiple grant mode or piggyback mode for performing fragmentation. A CMTS MAY support both fragmentation modes.
+
+Multiple grant mode allows the CMTS to break a request up into two or more grants in a single or over successive maps and it calculates the additional overhead required in the remaining partial grants to satisfy the request. In multiple grant mode, if the CMTS cannot grant the remainder in the current MAP, it MUST send a grant pending (zero length grant) in the current MAP and all subsequent MAPs to the CM until it can grant additional bandwidth. If there is no grant or grant pending in subsequent MAPs, the CM MUST re-request for the remainder. This re-request mechanism is the same as that used when a normal REQ does not receive a grant or grant pending within the ack time.
+
+If a CM receives a grant pending IE along with a fragment grant, it MUST NOT piggyback a request in the extended header of the fragment transmitted in that grant.
+
+In the case where the CM misses a grant and re-requests the remaining bandwidth, the CMTS MUST recover without dropping the frame.
+
+Due to the imprecision of the mini-slot to byte conversion process, the CMTS may not be able to calculate exactly the number of extra mini-slots needed to allow for fragmentation overhead. Also because it is possible for a CM to have missed a map with a partial grant, and thus to be requesting to send an unsent fragment rather than a new PDU, the CMTS cannot be certain whether the CM has already accounted for fragmentation overhead in a request. Therefore, the CMTS MUST make sure that any fragment payload remainder is at least one mini-slot greater than the number of mini-slots needed to contain the overhead for a fragment (16 bytes) plus the physical layer overhead necessary to transmit a minimum-sized fragment. Failure to do this may cause the CMTS to issue a grant that is not needed as the CM has completed transmission of the fragment payload remainder using the previous partial grant. This may cause the CM to get out of sync with the CMTS by inadvertently starting a new fragmentation. Also the CMTS needs to deal with the fact that with certain sets of physical layer parameters, the CM may request one more mini-slot than the maximum size of a short data grant, but not actually need that many mini-slots. This happens in the case where the CM needs to push the request size beyond the short data grant limit. The CMTS needs a policy to ensure that fragmenting such requests in multiple grant mode does not lead to unneeded fragmentary grants.
+
+### 10.3.2.2 Piggyback mode
+
+If the CMTS does not put another partial grant or a grant pending in the MAP in which it initiates fragmentation on a SID, the CM MUST automatically piggyback for the remainder. The CM calculates how much of a frame can be sent in the granted bandwidth and forms a fragment to send it. The CM utilizes the piggyback field in the fragment extended header to request the bandwidth necessary to transfer the remainder of the frame. Since the CMTS did not indicate a multiple grant in the first fragment MAP, the CM MUST keep track of the remainder to send. The request length, including physical-layer and fragmentation overhead, for the remainder of the original frame is inserted into the piggyback request byte in the fragmentation header.
+
+If the fragment HCS is correct, the piggybacked request, if present, is passed on to the bandwidth allocation process while the fragment itself is enqueued for reassembly. Once the complete MAC frame is reassembled, and it has been determined that the HCS is correct, the CMTS processes the frame as though it had been received unfragmented except that the CMTS MUST ignore the decryption-related portion of any privacy EHDRs. However, the bandwidth requests in privacy EHDRs and request EHDRs of such frames SHOULD be processed, but they MAY be ignored also.
+
+### 10.3.3 Fragmentation example
+
+#### 10.3.3.1 Single packet fragmentation
+
+Refer to Figure 10-9. Assume that fragmentation has been enabled for a given SID.
+
+- 1) (Requesting state) – CM wants to transmit a 1018-byte packet. CM calculates how much physical layer overhead (POH) is required and requests the appropriate number of mini-slots. CM makes a request in a contention region. Go to step 2.
+- 2) (Waiting for grant) – CM monitors MAPs for a grant or grant pending for this SID. If the CM's ack time expires before the CM receives a grant or grant pending, the CM retries requesting for the packet until the retry count is exhausted – then the CM gives up on that packet. Go to step 3.
+- 3) (First fragment) – Prior to giving up in step 2, the CM sees a grant for this SID that is less than the requested number of mini-slots. The CM calculates how much MAC information can be sent in the granted number of mini-slots using the specified burst profile. In the example in Figure 10-9, the first grant can hold 900 bytes after subtracting the POH. Since the fragment overhead (FRAG HDR, FHCS and FCRC) is 16 bytes, 884 bytes of the original packet can be carried in the fragment. The CM creates a fragment composed of the FRAG HDR, FHCS, 884 bytes of the original packet, and an FCRC. The CM marks the fragment as first and prepares to send the fragment. Go to step 4.
+- 4) (First fragment, multiple grant mode) – CM looks to see if there are any other grants or grant pendings enqueued for this SID. If so, the CM sends the fragment with the piggyback field in the FRAG HDR set to zero and awaits the time of the subsequent grant to roll around. Go to step 6. If there are not any grants or grant pendings, go to step 5.
+- 5) (First fragment, piggyback mode) – If there are no other grants or grant pendings for this SID in this MAP, the CM calculates how many mini-slots are required to send the remainder of the fragmented packet, including the fragmentation overhead, and physical layer overhead, and inserts this amount into the piggyback field of the FRAG HDR. The CM then sends the fragment and starts its ack timer for the piggyback request. In the example in Figure 10-9, the CM sends up a request for enough mini-slots to hold the POH plus 150 bytes (1018 – 884 + 16). Go to step 6.
+- 6) (Waiting for grant) – The CM is now waiting for a grant for the next fragment. If the CM's ack timer expires while waiting on this grant, the CM should send up a request for enough mini-slots to send the remainder of the fragmented packet, including the fragmentation overhead, and physical layer overhead. Go to step 7.
+- 7) (Receives next fragment grant) – Prior to giving up in step 6, the CM sees another grant for this SID. The CM checks to see if the grant size is large enough to hold the remainder of the fragmented packet, including the fragmentation overhead and physical layer overhead. If so, go to step 10. If not, go to step 8.
+- 8) (Middle fragment, multiple grant mode) – Since the remainder of the packet (plus overhead) will not fit in the grant, the CM calculates what portion will fit. The CM encapsulates this portion of the packet as a middle fragment. The CM then looks for any other grants or grant pendings enqueued for this SID. If either are present, the CM sends the fragment with the piggyback field in the FRAG HDR set to zero and awaits the time of the subsequent grant to roll around. Go to step 6. If there are not any grants or grant pendings, go to step 9.
+- 9) (Middle fragment, piggyback mode) – The CM calculates how many mini-slots are required to send the remainder of the fragmented packet, including the fragmentation overhead and physical layer overhead, and inserts this amount into the piggyback field of the FRAG HDR. The CM then sends the fragment and starts its ack timer for the piggyback request. Go to step 6.
+
+- 10) (Last fragment) – The CM encapsulates the remainder of the packet as a last fragment. If there is no other packet enqueued or there is a another grant or a grant pending enqueued for this SID, the CM places a zero in the REQ field of the FRAG HDR. If there is another packet enqueued with no grant or grant pending, the CM calculates the number of mini-slots required to send the next packet and places this number in the REQ field in the FRAG HDR. The CM then transmits the packet. Go to step 11. In the example in Figure 10-9, the grant is large enough to hold the remaining 150 bytes plus POH.
+- 11) (Normal operation) – The CM then returns the normal operation of waiting for grants and requesting for packets. If at any time fragmentation is enabled and a grant arrives that is smaller than the request, the fragmentation process starts again as in step 2.
+
+![](687c1faf4209421db20c72c280b06a3d_img.jpg)
+
+Original packet with BPI EHDR (1018 bytes)
+
+|     |      |     |     |             |     |             |      |
+|-----|------|-----|-----|-------------|-----|-------------|------|
+| 1 B | 1 B  | 2 B | 4 B | 4 B         | 2 B | 1000 B      | 4 B  |
+| FC  | PARM | LEN | PRV | Other EHDRs | HCS | PDU payload | PCRC |
+
+Fragment payload
+
+884 (900 – 16) bytes sent in first fragment
+
+134 (1018 – 884) bytes sent in last fragment
+
+---
+
+First grant can fit 900 bytes of MAC information
+
+|          |      |     |      |     |     |             |     |                     |      |
+|----------|------|-----|------|-----|-----|-------------|-----|---------------------|------|
+| 10 B     | 2 B  | 1 B | 1 B  | 2 B | 4 B | 4 B         | 2 B | 870 B               | 4 B  |
+| FRAG HDR | FHCS | FC  | PARM | LEN | PRV | Other EHDRs | HCS | PDU payload (first) | FCRC |
+
+Encrypted under baseline privacy
+
+|     |              |     |          |
+|-----|--------------|-----|----------|
+| 1 B | 1 B          | 2 B | 6 B      |
+| FC  | EHDR LEN = 6 | LEN | BPI EHDR |
+
+|    |       |   |
+|----|-------|---|
+| 11 | 00011 | 1 |
+|----|-------|---|
+
+|     |     |             |     |           |
+|-----|-----|-------------|-----|-----------|
+| 1 B | 1 B | 2 B         | 1 B | 1 B       |
+| 35  | Ver | E T QoS_SID | RQ  | Frag cntl |
+
+Request for enough mini-slots to fit 150 (130 + 4 + 16) bytes of MAC info. This field would be zero in multiple grant mode.
+
+|          |
+|----------|
+| 00100000 |
+|----------|
+
+---
+
+Second grant can fit 150 bytes of MAC information
+
+|          |      |                     |      |      |
+|----------|------|---------------------|------|------|
+| 10 B     | 2 B  | 130 B               | 4 B  | 4 B  |
+| FRAG HDR | FHCS | PDU payload (cont.) | PCRC | FCRC |
+
+Encrypted under baseline privacy
+
+|     |              |     |          |
+|-----|--------------|-----|----------|
+| 1 B | 1 B          | 2 B | 6 B      |
+| FC  | EHDR LEN = 6 | LEN | BPI EHDR |
+
+|    |       |   |
+|----|-------|---|
+| 11 | 00011 | 1 |
+|----|-------|---|
+
+|     |     |             |     |
+|-----|-----|-------------|-----|
+| 1 B | 2 B | 1 B         | 1 B |
+| 35  | Ver | E T QoS_SID | RQ  |
+
+Piggyback request for next PDU (if applicable)
+
+|          |
+|----------|
+| 00010001 |
+|----------|
+
+J.122\_F10-9
+
+Frag cntl bit definition
+
+|    |    |      |
+|----|----|------|
+| XX | FL | SSSS |
+|----|----|------|
+
+- XX Reserved, set to 00
+- F Set on first fragment, clear otherwise
+- L Set on last fragment, clear otherwise
+- SSSS 4-bit sequence number, increments on each fragment of a frame, rolling over as necessary
+
+Figure 10-9 – Example of fragmenting a single packet
+
+10.3.3.2 Concatenated packet fragmentation
+
+After the CM creates the concatenated packet, the CM treats the concatenated packet as a single PDU. Figure 10-10 shows an example of a concatenated packet broken into 3 fragments. Note that the packet is fragmented without regard to the packet boundaries within the concatenated packet.
+
+Original concatenated packet  
+(287 bytes)
+
+![Diagram of the original concatenated packet structure showing fields: Concat. HDR (6 B), MAC HDR1 (15 B), PDU payload 1 (68 B), PCRC1 (4 B), MAC HDR2 (6 B), PDU payload 2 (100 B), PCRC2 (4 B), MAC HDR3 (10 B), PDU payload 3 (70 B), and PCRC3 (4 B). Below Concat. HDR and MAC HDR1, details show FC (1 B), EHDR LEN=6 (1 B), LEN (2 B), and HCS (2 B). Below MAC HDR2, details show FC (1 B), PARM (1 B), LEN (2 B), PRV (4 B), Other EHDRs (5 B), and HCS (2 B).](f912dca77834dec85a50503dea8c99be_img.jpg)
+
+Diagram of the original concatenated packet structure showing fields: Concat. HDR (6 B), MAC HDR1 (15 B), PDU payload 1 (68 B), PCRC1 (4 B), MAC HDR2 (6 B), PDU payload 2 (100 B), PCRC2 (4 B), MAC HDR3 (10 B), PDU payload 3 (70 B), and PCRC3 (4 B). Below Concat. HDR and MAC HDR1, details show FC (1 B), EHDR LEN=6 (1 B), LEN (2 B), and HCS (2 B). Below MAC HDR2, details show FC (1 B), PARM (1 B), LEN (2 B), PRV (4 B), Other EHDRs (5 B), and HCS (2 B).
+
+First grant can fit  
+125 bytes of  
+MAC information
+
+![Diagram of the first grant structure. The packet starts with FRAG HDR (10 B) and FHCS (2 B). Below FRAG HDR are FC (1 B), EHDR LEN=6 (1 B), and LEN (2 B). Below FHCS is BPI EHDR (6 B), which contains E|T|QoS_SID (1 B), RQ (1 B), and Frag cntl (1 B). The RQ field is expanded to show a request for 162 mini-slots (00100000). The remaining packet structure is Concat. HDR (6 B), MAC HDR1 (15 B), PDU payload 1 (68 B), PCRC1 (4 B), MAC HDR2 (6 B), PDU payload 2 (part 1) (10 B), and FCRC (4 B). A bracket indicates the portion from MAC HDR1 to the end is 'Encrypted under baseline privacy'. A note states: 'Request for enough mini-slots to fit 162 (287 - 109 + 16) bytes of MAC info. This field would be zero in multiple grant mode.'](5cdc04ba574b7b819a3cb6dbbd91306c_img.jpg)
+
+Diagram of the first grant structure. The packet starts with FRAG HDR (10 B) and FHCS (2 B). Below FRAG HDR are FC (1 B), EHDR LEN=6 (1 B), and LEN (2 B). Below FHCS is BPI EHDR (6 B), which contains E|T|QoS\_SID (1 B), RQ (1 B), and Frag cntl (1 B). The RQ field is expanded to show a request for 162 mini-slots (00100000). The remaining packet structure is Concat. HDR (6 B), MAC HDR1 (15 B), PDU payload 1 (68 B), PCRC1 (4 B), MAC HDR2 (6 B), PDU payload 2 (part 1) (10 B), and FCRC (4 B). A bracket indicates the portion from MAC HDR1 to the end is 'Encrypted under baseline privacy'. A note states: 'Request for enough mini-slots to fit 162 (287 - 109 + 16) bytes of MAC info. This field would be zero in multiple grant mode.'
+
+Second grant  
+can fit 146 bytes  
+of MAC  
+information
+
+![Diagram of the second grant structure. It starts with FRAG HDR (10 B) and FHCS (2 B). Below FRAG HDR are FC (1 B), EHDR LEN=6 (1 B), and LEN (2 B). Below FHCS is BPI EHDR (6 B), containing E|T|QoS_SID (1 B), RQ (1 B), and Frag cntl (1 B). The RQ field is expanded to show a request for 64 mini-slots (00000001). The remaining packet structure is PDU payload 2 (part 2) (90 B), PCRC2 (4 B), MAC HDR3 (10 B), PDU payload 3 (part 1) (26 B), and FCRC (4 B). A bracket indicates the portion from PDU payload 2 (part 2) to the end is 'Encrypted under baseline privacy'. A note states: 'Request for enough mini-slots to fit 64 (287 - 109 - 130 + 16) bytes of MAC info. This field would be zero in multiple grant mode.'](eeb519f37cc42888fa15ab9ea20ba7cb_img.jpg)
+
+Diagram of the second grant structure. It starts with FRAG HDR (10 B) and FHCS (2 B). Below FRAG HDR are FC (1 B), EHDR LEN=6 (1 B), and LEN (2 B). Below FHCS is BPI EHDR (6 B), containing E|T|QoS\_SID (1 B), RQ (1 B), and Frag cntl (1 B). The RQ field is expanded to show a request for 64 mini-slots (00000001). The remaining packet structure is PDU payload 2 (part 2) (90 B), PCRC2 (4 B), MAC HDR3 (10 B), PDU payload 3 (part 1) (26 B), and FCRC (4 B). A bracket indicates the portion from PDU payload 2 (part 2) to the end is 'Encrypted under baseline privacy'. A note states: 'Request for enough mini-slots to fit 64 (287 - 109 - 130 + 16) bytes of MAC info. This field would be zero in multiple grant mode.'
+
+Third grant can  
+fit 64 bytes of  
+MAC information
+
+![Diagram of the third grant structure. It starts with FRAG HDR (10 B) and FHCS (2 B). Below FRAG HDR are FC (1 B), EHDR LEN=6 (1 B), and LEN (2 B). Below FHCS is BPI EHDR (6 B), containing E|T|QoS_SID (1 B), RQ (1 B), and Frag cntl (1 B). The RQ field is expanded to show a request for the next packet (00010010). The remaining packet structure is PDU payload 3 (part 2) (44 B), PCRC3 (4 B), and FCRC (4 B). A bracket indicates the portion from PDU payload 3 (part 2) to the end is 'Encrypted under baseline privacy'. A note states: 'Request for next packet'. A label 'J.122_F10-10' is present.](b622fae9c3e43535a9915d1c912693fd_img.jpg)
+
+Diagram of the third grant structure. It starts with FRAG HDR (10 B) and FHCS (2 B). Below FRAG HDR are FC (1 B), EHDR LEN=6 (1 B), and LEN (2 B). Below FHCS is BPI EHDR (6 B), containing E|T|QoS\_SID (1 B), RQ (1 B), and Frag cntl (1 B). The RQ field is expanded to show a request for the next packet (00010010). The remaining packet structure is PDU payload 3 (part 2) (44 B), PCRC3 (4 B), and FCRC (4 B). A bracket indicates the portion from PDU payload 3 (part 2) to the end is 'Encrypted under baseline privacy'. A note states: 'Request for next packet'. A label 'J.122\_F10-10' is present.
+
+**Figure 10-10 – Fragmented concatenated packet example**
+
+### 10.4 Payload header suppression
+
+This overview clause explains the principles of payload header suppression. The subsequent clauses explain the signalling for initialization, operation and termination. Finally, specific upstream and downstream examples are given. The definitions shown in Table 10-5 are used.
+
+**Table 10-5 – Payload header suppression definitions**
+
+|                 |                                   |                                                                                                                                                                                                           |
+|-----------------|-----------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| <b>PHS</b>      | Payload header suppression        | Suppressing an initial byte string at the sender and restoring the byte string at the receiver                                                                                                            |
+| <b>PHS rule</b> | Payload header suppression rule   | A set of TLVs that apply to a specific PHS index                                                                                                                                                          |
+| <b>PHSF</b>     | Payload header suppression field  | A string of bytes representing the header portion of a PDU in which one or more bytes will be suppressed (i.e., a snapshot of the uncompressed PDU header inclusive of suppressed and unsuppressed bytes) |
+| <b>PHSI</b>     | Payload header suppression index  | An 8-bit value that references the suppressed byte string                                                                                                                                                 |
+| <b>PHSM</b>     | Payload header suppression mask   | A bit mask that indicates which bytes in the PHSF to suppress and which bytes to not suppress                                                                                                             |
+| <b>PHSS</b>     | Payload header suppression size   | The length of the suppressed field in bytes. This value is equivalent to the number of bytes in the PHSF and also the number of valid bits in the PHSM                                                    |
+| <b>PHSV</b>     | Payload header suppression verify | A flag that tells the sending entity to verify all bytes that are to be suppressed                                                                                                                        |
+
+#### 10.4.1 Overview
+
+In payload header suppression, a repetitive portion of the payload headers following the extended header field is suppressed by the sending entity and restored by the receiving entity. In the upstream, the sending entity is the CM and the receiving entity is the CMTS. In the downstream, the sending entity is the CMTS and the receiving entity is the CM. The MAC extended header contains a payload header suppression index (PHSI) that references the payload header suppression field (PHSF).
+
+Although PHS may be used with any service flow type, it has been designed for use with the unsolicited grant service (UGS) scheduling type. UGS works most efficiently with packets of a fixed length. PHS works well with UGS because, unlike other header compression schemes sometimes used with IP data, PHS always suppresses the same number of bytes in each packet. PHS will always produce a fixed length compressed packet header.
+
+The sending entity uses classifiers to map packets into a service flow. The classifier uniquely maps packets to its associated payload header suppression rule. The receiving entity uses the service identifier (SID) and the PHSI to restore the PHSR.
+
+Once the PHSF and PHSS fields of a rule are known, the rule is considered "fully defined" and none of its fields can be changed. If modified PHS operation is desired for packets classified to the flow, the old rule must be removed from the service flow and a new rule must be installed.
+
+When a classifier is deleted, any associated PHS rule MUST also be deleted.
+
+PHS has a PHSV option to verify or not verify the payload before suppressing it. PHS also has a PHSM option to allow select bytes not to be suppressed. This is used for sending bytes that change, such as IP sequence numbers, and still suppressing bytes that do not change.
+
+PHS rules are consistent for all scheduling service types. Requests and grants of bandwidth are specified after suppression has been accounted for. For unsolicited grant services, the grant size is chosen with the unsolicited grant size TLV. The packet with its header suppressed may be equal to or less than the grant size.
+
+The CMTS MUST assign all PHSI values just as it assigns all SID values. Either the sending or the receiving entity MAY specify the PHSF and PHSS. This provision allows for pre-configured headers, or for higher level signalling protocols outside the scope of this Recommendation to establish cache entries. PHS is intended for unicast service, and is not defined for multicast service.
+
+It is the responsibility of the higher-layer service entity to generate a PHS rule that uniquely identifies the suppressed header within the service flow. It is also the responsibility of the higher-layer service entity to guarantee that the byte strings being suppressed are constant from packet to packet for the duration of the active service flow.
+
+#### 10.4.2 Example applications
+
+- A classifier on an upstream service flow that uniquely defines a voice over IP (VoIP) flow by specifying protocol type of UDP, IP SA, IP DA, UDP source port, UDP destination port, the service flow reference, and a PHS Size of 42 bytes. A PHS rule references this classifier providing a PHSI value that identifies this VoIP media flow. For the upstream case, 42 bytes of payload header are verified and suppressed, and a 2-byte extended header containing the PHSI is added to every packet in that media flow.
+- A classifier that identifies the packets in a service flow, of which 90% match the PHSR. Verification is enabled. This may apply in a packet compression situation where every so often compression resets are done and the header varies. In this example, the scheduling algorithm would allow variable bandwidth, and only 90% of the packets might get their headers suppressed. Since the existence of the PHSI extended header will indicate the choice made, the simple SID/PHSI lookup at the receiving entity will always yield the correct result.
+- A classifier on an upstream service flow that identifies all IP packets by specifying ethertype of IP, the service flow ID, a PHSS of 14 bytes, and no verification by the sending entity. In this example, the CMTS has decided to route the packet, and knows that it will not require the first 14 bytes of the Ethernet header, even though some parts such as the source address or destination address may vary. The CM removes 14 bytes from each upstream frame (Ethernet header) without verifying their contents and forwards the frame to the service flow.
+
+#### 10.4.3 Operation
+
+To clarify operational packet flow, this clause describes one potential implementation. CM and CMTS implementations are free to implement payload header suppression in any manner as long as the protocol specified in this clause is followed. Figure 10-11 illustrates the following procedure.
+
+A packet is submitted to the CM MAC service layer. The CM applies its list of classifier rules. A match of the rule will result in an upstream service flow, SID and a PHS rule. The PHS rule provides PHSF, PHSI, PHSM, PHSS and PHSV. If PHSV is set to zero, or is not present, the CM will compare the bytes in the packet header with the bytes in the PHSF that are to be suppressed as indicated by the PHSM. If they match, the CM will suppress all the bytes in the upstream suppression field except the bytes masked by PHSM. The CM will then insert the PHSI into the PHS\_Parm field of the service flow EH element, and queue the packet on the upstream service flow.
+
+When the packet is received by the CMTS, the CMTS will determine the associated SID either by internal means or from other extended headers elements such as the BPI extended header. The CMTS uses the SID and the PHSI to look up PHSF, PHSM and PHSS. The CMTS reassembles the packet and then proceeds with normal packet processing. The reassembled packet will contain bytes from the PHSF. If verification was enabled, then the PHSF bytes will equal the original header bytes. If verification was not enabled, then there is no guarantee that the PHSF bytes will match the original header bytes.
+
+![Flowchart illustrating Payload header suppression operation. The diagram is split into two vertical columns: 'Sender PHS start' on the left and 'Receiver PHS start' on the right. The sender's path involves packet arrival, classification, verification, and suppression logic. The receiver's path involves identifying the SID, retrieving suppression fields, reconstructing the header, and forwarding the packet.](16e51d129488f259ccb14ae0db85061e_img.jpg)
+
+```
+
+graph TD
+    subgraph Sender
+        S1([Sender PHS start]) --> S2[/Packet arrives/]
+        S2 --> S3[Classify packet  
+retrieve PHSF, PHSI,  
+PHSM, PHSS, PHSV]
+        S3 --> S4{Verify ?}
+        S4 -- Yes --> S5[Verify with  
+PHSF]
+        S4 -- No --> S6[Suppress with  
+PHSM  
+append PHSI]
+        S5 --> S7{Pass  
+verify ?}
+        S7 -- Yes --> S6
+        S7 -- No --> S6
+        S6 --> S8[/Forward  
+packet/]
+        S8 --> S9([END])
+    end
+    subgraph Receiver
+        R1([Receiver PHS start]) --> R2[/Packet arrives/]
+        R2 --> R3[Identify SID and extract  
+PHSI]
+        R3 --> R4[Retrieve PHSF, PHSM,  
+PHSS]
+        R4 --> R5[Reconstruct header and  
+forward packet]
+        R5 --> R6[/Forward  
+packet/]
+        R6 --> R7([END])
+    end
+  
+```
+
+J.122\_F.10-11
+
+Flowchart illustrating Payload header suppression operation. The diagram is split into two vertical columns: 'Sender PHS start' on the left and 'Receiver PHS start' on the right. The sender's path involves packet arrival, classification, verification, and suppression logic. The receiver's path involves identifying the SID, retrieving suppression fields, reconstructing the header, and forwarding the packet.
+
+**Figure 10-11 – Payload header suppression operation**
+
+A similar operation occurs in the downstream. The CMTS applies its list of classifiers. A match of the classifier will result in a downstream service flow and a PHS rule. The PHS rule provides PHSF, PHSI, PHSM, PHSS and PHSV. If PHSV is set to zero, or is not present, the CMTS will verify the downstream suppression field in the packet with the PHSF. If they match, the CMTS will suppress all the bytes in the downstream suppression field except the bytes masked by PHSM. The CMTS will then insert the PHSI into the PHS\_Parm field of the service flow EH element, and queue the packet on the downstream service flow.
+
+The CM will receive the packet based upon the Ethernet destination address filtering. The CM then uses the PHSI to lookup PHSF, PHSM and PHSS. The CM reassembles the packet and then proceeds with normal packet processing.
+
+Figure 10-12 demonstrates packet suppression and restoration when using PHS masking. Masking allows only bytes that do not change to be suppressed. Note that the PHSF and PHSM span the entire suppression field, including suppressed and unsuppressed bytes.
+
+![Diagram illustrating payload header suppression with masking across a sender, cable network, and receiver. It shows the mapping of current headers (A-E) to cached headers (A'-E') using a suppression mask (PHSM) and suppression field (PHSF).](16563dc7c141a645e1b8cd9c4aa1cb23_img.jpg)
+
+The diagram illustrates the process of payload header suppression and restoration. It is divided into three main sections: Sender, Cable network, and Receiver.
+
+- Sender:**
+  - Current header: A B C D E
+  - PHSM (Payload Header Suppression Mask): 1 0 1 0 1
+  - PHSF (Payload Header Suppression Field): A' X C' X E'
+- Cable network:**
+  - Suppressed header: B D
+- Receiver:**
+  - PHSM: 1 0 1 0 1
+  - PHSF: A' X C' X E'
+  - Restored header: A' B C' D E'
+
+Arrows indicate the flow of data: from Sender's current header to PHSM and PHSF, then to the Cable network, then to the Receiver's PHSM and PHSF, and finally to the restored header. Dashed arrows show the mapping from Sender's PHSF to the Cable network and from the Cable network to the Receiver's PHSF.
+
+Legend:
+
+- Verify (solid double-headed arrow)
+- Assign (dashed double-headed arrow)
+- A-E: Current header
+- A'-E': Cached header
+- X: Don't care
+- PHSS: 5
+
+J.122\_F10-12
+
+Diagram illustrating payload header suppression with masking across a sender, cable network, and receiver. It shows the mapping of current headers (A-E) to cached headers (A'-E') using a suppression mask (PHSM) and suppression field (PHSF).
+
+Figure 10-12 – Payload header suppression with masking
+
+#### 10.4.4 Signalling
+
+Payload header suppression requires the creation of three objects:
+
+- service flow;
+- classifier;
+- payload header suppression rule.
+
+These three objects MAY be created in separate message flows, or MAY be created simultaneously.
+
+PHS rules are created with registration, DSA or DSC messages. The CMTS MUST define the PHSI when the PHS rule is created. PHS rules are deleted with the DSC or DSD messages. The CM or CMTS MAY define the PHSS and PHSF.
+
+Figure 10-13 shows the two ways to signal the creation of a PHS Rule.
+
+It is possible to partially define a PHS rule (in particular, the size of the rule) at the time a service flow is created.
+
+As an example, it is likely that when a service flow is first provisioned, the size of the header field to be suppressed will be known. The values of some items within the field (e.g., IP addresses, UDP port numbers, etc.) may not be known and would be provided in a subsequent DSC as part of the activation of the service flow (using the "set PHS rule" DSC action).
+
+A PHS rule is partially defined when the PHSF and PHSS field values are not both known. Once both PHSF and PHSS are known, the rule is considered fully defined, and MUST NOT be modified
+
+via DSC signalling. PHSV and PHSM fields have default values, thus are not required to fully define a PHS rule. If PHSV and PHSM are not known when the rule becomes fully defined, their default values are used, and MUST NOT be modified via DSC signalling.
+
+Each step of the PHS rule definition, whether it is a registration request, DSA or a DSC, MUST contain service flow ID (or reference), classifier ID (or reference) to uniquely identify the PHS rule being defined. A PHS index and service ID pair is used to uniquely identify the PHS rule during upstream packet transfer. A PHS index is enough to uniquely identify the PHS rule used in downstream packet transfer.
+
+#### 10.4.5 Payload header suppression examples
+
+![](cdb980c2fe504f3132b907d4de707c7f_img.jpg)
+
+| CMTS-initiated |                                                           | CM-initiated                                                     |         |
+|----------------|-----------------------------------------------------------|------------------------------------------------------------------|---------|
+| CMTS           | CM                                                        | CMTS                                                             | CM      |
+| DSC-REQ        | → Classifier ID + service flow ID<br>+ PHSI + PHSS + PHSF | ← Classifier reference/<br>ID + service flow ID<br>+ PHSS + PHSF | DSC-REQ |
+| DSC-RSP        | ←                                                         | → PHSI                                                           | DSC-RSP |
+| DSC-ACK        | →                                                         | ←                                                                | DSC-ACK |
+
+J.122\_F10-13
+
+Figure 10-13 – Payload header suppression signalling example
+
+##### 10.4.5.1 Upstream example
+
+A service class with the service class name of "G711-US-UGS-HS-42" is established, which is intended for G.711 VoIP traffic in the upstream with unsolicited grant service. When classifiers are added to the flow, a PHSS value of 42 is included, which explicitly states that the first 42 bytes following the MAC extended header on all packets in that flow must be verified, suppressed and restored. In this example, the service class is configured such that any packet that does not verify correctly will not have its header suppressed and will be discarded since it will exceed the unsolicited grant size (refer to clause C.2.2.6.3).
+
+Figure 10-14 shows the encapsulation used in the upstream with and without payload header suppression. An RTP voice over IP payload without IPsec is used as a specific example to demonstrate efficiency.
+
+a) VoIP with normal encapsulation
+
+![Diagram showing normal VoIP encapsulation with fields: FGPS (14-34), MAC OH (4), BPI (5), HCS (2), Ethernet (14), IP (20), UDP (8), RTP (12), Voice bytes (10 to 160), CRC (4). A dashed line indicates suppression of Ethernet, IP, and UDP headers in the next diagram.](b80d6831090336de8afda95bd19972e6_img.jpg)
+
+|       |        |     |     |          |    |     |     |             |     |
+|-------|--------|-----|-----|----------|----|-----|-----|-------------|-----|
+| 14-34 | 4      | 5   | 2   | 14       | 20 | 8   | 12  | 10 to 160   | 4   |
+| FGPS  | MAC OH | BPI | HCS | Ethernet | IP | UDP | RTP | Voice bytes | CRC |
+
+  
+
+|       |        |     |   |     |     |             |     |                 |
+|-------|--------|-----|---|-----|-----|-------------|-----|-----------------|
+| 14-34 | 4      | 5   | 2 | 2   | 12  | 10 to 160   | 4   | values in bytes |
+| FGPS  | MAC OH | BPI | P | HCS | RTP | Voice bytes | CRC |                 |
+
+Diagram showing normal VoIP encapsulation with fields: FGPS (14-34), MAC OH (4), BPI (5), HCS (2), Ethernet (14), IP (20), UDP (8), RTP (12), Voice bytes (10 to 160), CRC (4). A dashed line indicates suppression of Ethernet, IP, and UDP headers in the next diagram.
+
+b) VoIP with header suppression
+
+J.122\_F10-14
+
+Figure 10-14 – Upstream payload header suppression example
+
+Figure 10-14 a) shows a normal RTP packet carried on an upstream channel. The beginning of the frame represents the physical layer overhead (FGPS) of FEC, guard time, preamble and stuffing bytes. Stuffing bytes occur in the last code word and when mapping blocks to mini-slots. Next is the MAC layer overhead including the 6-byte MAC header with a 5-byte BPI extended header, the 14-byte Ethernet header, and the 4-byte Ethernet CRC trailer. The VoIP payload uses a 20-byte IP header, an 8-byte UDP header, and a 12-byte RTP header. The voice payload is variable and depends upon the sample time and the compression algorithm used.
+
+Figure 10-14 b) shows the same payload with payload header suppression enabled. In the upstream, payload header suppression begins with the first byte after the MAC header checksum. The 14-byte Ethernet header, the 20-byte IP header, and the 8-byte UDP header have been suppressed, and a 2-byte PHS extended header element has been added, for a net reduction of 40 bytes. In this example of an established VoIP connection, these fields remain constant from packet to packet, and are otherwise redundant.
+
+10.4.5.2 Downstream example
+
+A service class with the service class name of "G711-DS-HS-30" is established, which is intended for G.711 VoIP traffic in the downstream. When classifiers are added to the service flow, a PHSS value of 30 is included which explicitly indicates that 30 bytes of the payload header on all packets must be processed for suppression and restoration according to the PHSM. Any packet that does not verify correctly will not have its header suppressed but will be transmitted subject to the traffic shaping rules in place for that service flow.
+
+Figure 10-15 shows the encapsulation used in the downstream with and without payload header suppression. An RTP voice over IP payload without IPsec is used as a specific example to demonstrate efficiency.
+
+a) VoIP with normal encapsulation
+
+![Diagram showing normal VoIP encapsulation with fields: MAC OH (4), BPI (5), HCS (2), DA (6), SA (6), T (2), IP (20), UDP (8), RTP (12), Voice bytes (10 to 160), CRC (4). A dashed line indicates suppression of DA, SA, T, IP, and UDP headers in the next diagram.](873275851761a3173ee66f649493aea3_img.jpg)
+
+|        |     |     |    |    |   |    |     |     |             |     |
+|--------|-----|-----|----|----|---|----|-----|-----|-------------|-----|
+| 4      | 5   | 2   | 6  | 6  | 2 | 20 | 8   | 12  | 10 to 160   | 4   |
+| MAC OH | BPI | HCS | DA | SA | T | IP | UDP | RTP | Voice bytes | CRC |
+
+  
+
+|        |     |   |     |    |    |     |             |     |                 |
+|--------|-----|---|-----|----|----|-----|-------------|-----|-----------------|
+| 4      | 5   | 2 | 2   | 6  | 6  | 12  | 10 to 160   | 4   | Values in bytes |
+| MAC OH | BPI | P | HCS | DA | SA | RTP | Voice bytes | CRC |                 |
+
+Diagram showing normal VoIP encapsulation with fields: MAC OH (4), BPI (5), HCS (2), DA (6), SA (6), T (2), IP (20), UDP (8), RTP (12), Voice bytes (10 to 160), CRC (4). A dashed line indicates suppression of DA, SA, T, IP, and UDP headers in the next diagram.
+
+b) VoIP with header suppression
+
+J.122\_F10-15
+
+Figure 10-15 – Downstream payload header suppression example
+
+Figure 10-15 a) shows a normal RTP packet carried on a downstream channel. The layer 2 overhead includes the 6-byte MAC header with a 5-byte BPI extended header, the 14-byte Ethernet header (6-byte destination address, 6-byte source address, and 2-byte ethertype field), and the 4-byte Ethernet CRC trailer. The layer 3 VoIP payload uses a 20-byte IP header, an 8-byte UDP header, and a 12-byte RTP header. The voice payload is variable and depends upon the sample time and the compression algorithm used.
+
+Figure 10-15 b) shows the same payload with payload header suppression enabled. In the downstream, payload header suppression begins with the thirteenth byte after the MAC header checksum. This retains the Ethernet destination address and source address, which is required so that the CM may filter and receive the packet. The remaining 2 bytes of the Ethernet header, the 20-byte IP header, and the 8-byte UDP header have been suppressed, and a 2-byte PHS extended header element has been added, for a net reduction of 28 bytes. In this example of an established VoIP connection, these fields remain constant from packet to packet, and are thus redundant.
+
+## **11 Cable modem – CMTS interaction**
+
+This clause covers the key requirements for the interaction between a CM and a CMTS. It only covers interaction between a CM and CMTS that are both compliant with this version of the Recommendation, and only in the case where the CM is using a configuration file with QoS parameters compliant with this version of the Recommendation. Issues involving interoperability with equipment and configuration files compliant with previous versions of this Recommendation (DOCS 1.x) are discussed in Annex G. The interaction can be broken down into five basic categories: initialization, authentication, configuration, authorization and signalling.
+
+### **11.1 CMTS initialization**
+
+The mechanism utilized for CMTS initialization (local terminal, file download, SNMP, etc.) is described in [DOCS5]. It MUST meet the following criteria for system interoperability:
+
+- The CMTS MUST be able to reboot and operate in a stand-alone mode using configuration data retained in non-volatile storage.
+- If valid parameters are not available from non-volatile storage or via another mechanism such as the spectrum management system (see [b-VECCHI]), the CMTS MUST NOT generate any downstream messages (including SYNC). This will prevent CMs from transmitting.
+- The CMTS MUST provide the information defined in clause 8 to CMs for each upstream channel.
+
+### **11.2 Cable modem initialization**
+
+The procedure for initialization of a cable modem MUST be as shown in Figure 11-1. This figure shows the overall flow between the stages of initialization in a CM. This shows no error paths, and is simply to provide an overview of the process. The more detailed finite state machine representations of the individual sections (including error paths) are shown in the subsequent figures. Timeout values are defined in Annex B.
+
+![Flowchart of CM initialization overview. The process starts with 'Scan for downstream channel' and proceeds through 'Downstream sync established', 'Obtain upstream parameters', 'Upstream parameters acquired', 'Ranging and automatic adjustments', 'Ranging and auto adj complete', 'Device class identification (optional)', 'Establish IP connectivity', 'IP complete', and 'Establish time of day'. A line connects the bottom of the first column to the top of the second column starting with 'Time of day established'. The second column continues with 'Transfer operational parameters', 'Transfer complete', 'Register with CMTS', and 'Registration complete'. A decision diamond 'Baseline privacy enabled' follows. If 'No', it goes directly to 'Operational'. If 'Yes', it goes to 'Baseline privacy initialization', then 'Baseline privacy initialized', and finally 'Operational'.](e54b4825299a9c5abf4bdc11266ca4b5_img.jpg)
+
+```
+
+graph TD
+    A([Scan for downstream channel]) --> B[/Downstream sync established/]
+    B --> C([Obtain upstream parameters])
+    C --> D[/Upstream parameters acquired/]
+    D --> E([Ranging and automatic adjustments])
+    E --> F[/Ranging and auto adj complete/]
+    F --> G([Device class identification optional])
+    G --> H([Establish IP connectivity])
+    H --> I[/IP complete/]
+    I --> J([Establish time of day])
+    J --> K[/Time of day established/]
+    K --> L([Transfer operational parameters])
+    L --> M[/Transfer complete/]
+    M --> N([Register with CMTS])
+    N --> O[/Registration complete/]
+    O --> P{Baseline privacy enabled}
+    P -- No --> Q([Operational])
+    P -- Yes --> R([Baseline privacy initialization])
+    R --> S[/Baseline privacy initialized/]
+    S --> Q
+  
+```
+
+J.122\_F.11-1
+
+Flowchart of CM initialization overview. The process starts with 'Scan for downstream channel' and proceeds through 'Downstream sync established', 'Obtain upstream parameters', 'Upstream parameters acquired', 'Ranging and automatic adjustments', 'Ranging and auto adj complete', 'Device class identification (optional)', 'Establish IP connectivity', 'IP complete', and 'Establish time of day'. A line connects the bottom of the first column to the top of the second column starting with 'Time of day established'. The second column continues with 'Transfer operational parameters', 'Transfer complete', 'Register with CMTS', and 'Registration complete'. A decision diamond 'Baseline privacy enabled' follows. If 'No', it goes directly to 'Operational'. If 'Yes', it goes to 'Baseline privacy initialization', then 'Baseline privacy initialized', and finally 'Operational'.
+
+**Figure 11-1 – CM initialization overview**
+
+The procedure for initializing a cable modem and for a CM to re-initialize its MAC can be divided into the following phases:
+
+- scanning and synchronization to downstream;
+- obtaining upstream parameters;
+- ranging and automatic adjustments;
+- device class identification (optional);
+- establishing IP connectivity;
+- establishing time of day;
+- transferring operational parameters;
+- registration;
+
+- baseline privacy initialization, if CM is provisioned to run baseline privacy.
+
+Each CM contains the following information when shipped from the manufacturer:
+
+- A unique IEEE 802 48-bit MAC address that is assigned during the manufacturing process. This is used to identify the modem to the various provisioning servers during initialization.
+- Security information as defined in [DOCS8] (e.g., X.509 certificate) used to authenticate the CM to the security server and authenticate the responses from the security and provisioning servers.
+
+The SDL (specification and description language) notation used in the following figures is shown in Figure 11-2 (refer to [ITU-T Z.100]).
+
+![Figure 11-2 – SDL notation. This diagram shows various symbols used in SDL. It includes: State symbols (rounded rectangles); Input symbols, divided into Internal (a chevron pointing right with a double line on the right side) and External (a chevron pointing right with a single line on the right side); Task symbols (rectangles); Output symbols, divided into Internal (a chevron pointing right with a double line on the left side) and External (a chevron pointing right with a single line on the left side); and Decision symbols (diamonds). Each symbol is shown in two variations: a standard single-line version and a version with double lines on its vertical edges.](91f8008d6970ce8829ff74aa04e739d8_img.jpg)
+
+Figure 11-2 – SDL notation. This diagram shows various symbols used in SDL. It includes: State symbols (rounded rectangles); Input symbols, divided into Internal (a chevron pointing right with a double line on the right side) and External (a chevron pointing right with a single line on the right side); Task symbols (rectangles); Output symbols, divided into Internal (a chevron pointing right with a double line on the left side) and External (a chevron pointing right with a single line on the left side); and Decision symbols (diamonds). Each symbol is shown in two variations: a standard single-line version and a version with double lines on its vertical edges.
+
+J122\_F11-2
+
+**Figure 11-2 – SDL notation**
+
+### 11.2.1 Scanning and synchronization to downstream
+
+On initialization or a "re-initialize MAC" operation, the cable modem MUST acquire a downstream channel. The CM MUST have non-volatile storage in which the last operational parameters are stored and MUST first try to re-acquire this downstream channel. If this fails, it MUST begin to continuously scan the 6-MHz channels of the downstream frequency band of operation until it finds a valid downstream signal.
+
+A downstream signal is considered to be valid when the modem has achieved the following steps:
+
+- synchronization of the QAM symbol timing;
+- synchronization of the FEC framing;
+- synchronization of the MPEG packetization;
+- recognition of SYNC downstream MAC messages.
+
+While scanning, it is desirable to give an indication to the user that the CM is doing so.
+
+In order to support redundant CMTS architectures, when a CM in the operational state detects that the downstream signal is invalid (i.e., does not meet the four criteria above), the CM MUST NOT immediately perform a re-initialize MAC operation. It must instead attempt to re-establish synchronization on the current downstream channel (see clause 11.5). Such re-establishment attempts MUST continue until the operation of periodic ranging as specified in Figure 11-17 calls for a "re-initialize MAC" operation after the expiration of timeout T4 or 16 expirations of timeout T3. Figure 11-17 shows the procedure that MUST be followed by a cable modem during standard operation.
+
+An interruption of downstream signal occurs when the following conditions are met:
+
+- The interruption occurs on a downstream that is valid (per clauses 6.3.5, 6.3.6, 6.3.7, 6.3.8, 6.3.9 and 6.3.10) before and after the loss.
+- The interruption is defined as an instantaneous loss of signal and, after a predetermined delay, an instantaneous return to the original signal fidelity.
+- The restored downstream signal is the original signal transmitted from the original source.
+- The carrier frequency, physical plant and path delays remain the same before and after the interruption.
+- There are no changes in any downstream signalling parameter, including the modulation and the M/N ratio, from before to after the interruption.
+
+When a CM in the operational state in S-CDMA mode receives an interruption of downstream signal less than or equal to 5 ms, the CM MUST recover from the outage such that its fixed timing error is not greater than 0.02 of the nominal modulation interval (in addition to the allowed jitter defined in clause 6.2.21.8). When a CM in the operational state in TDMA mode receives an interruption of downstream signal less than or equal to 5 ms, the CM MUST recover from the outage such that the first upstream transmission after the CM resumes normal operation is performed within an accuracy of  $\pm 250$  nanoseconds plus  $\pm 0.5$  symbols (refer to clause 6.2.19.1). In either mode, the CM MUST continue with normal operation within 2 s from the end of the interruption. The CM is not required to continue normal operation if it receives a second interruption of downstream signal prior to the first receipt of a RNG-RSP with status "success".
+
+When a CM in the operational state receives an interruption of downstream signal greater than 5 ms but less than the lost sync interval (see Annex B), the CM MAY continue with normal operation as long as it recovers within 2 s:
+
+- with a fixed timing error not greater than 0.02 of the nominal modulation interval (in addition to the allowed jitter defined in clause 6.2.21.8), if the CM is in S-CDMA mode;
+- within the accuracy of clause 6.2.19.1, if the CM is in TDMA mode.
+
+If the CM cannot recover according to the preceding recovery time, timing and jitter specifications, the CM MUST re-acquire upstream timing to an accuracy of at least 1  $\mu\text{s}$  and be ready to respond to a ranging opportunity within 2 s, and MUST receive a RNG-RSP message with status "success" before resuming its upstream transmission. For the ranging process, the CM MAY use broadcast or unicast initial maintenance intervals, or station maintenance intervals, although a CM in S-CDMA mode MUST NOT use spreader-on station maintenance. For the ranging process, the CM MUST use its primary SID in the INIT-RNG-REQ or RNG-REQ message and MUST use its known timing offset. After completing this ranging process by receiving RNG-RSP with the ranging status set to "success", the CM MUST return to normal operation. A CMTS MUST process INIT-RNG-REQ messages with a primary SID from any CM that is in normal operation. If the primary SID used by the CM in INIT-RNG-REQ is no longer valid, the CMTS SHOULD send a RNG-RSP message to the CM with the ranging status set to "abort".
+
+In all cases, after the first successful ranging opportunity subsequent to the interruption, the CM MUST meet the timing requirements specified in clauses 6.2.19.1 and 6.2.21.8.
+
+### **11.2.2 Obtain upstream parameters**
+
+Refer to Figure 11-3. After synchronization, the CM MUST wait for an upstream channel descriptor message (UCD) from the CMTS in order to retrieve a set of transmission parameters for a possible upstream channel. These messages are transmitted periodically from the CMTS for all available upstream channels and are addressed to the MAC broadcast address. The CM MUST determine whether it can use the upstream channel from the channel description parameters.
+
+![Flowchart for obtaining upstream parameters. The process starts with 'Collect UCD Messages', leading to 'Build channel list' and 'Timeout T1'. 'Build channel list' leads to 'Select first channel', which leads to 'Wait for usable UCD'. 'Timeout T1' leads to 'Scanning', which leads to 'End of channel list?'. 'End of channel list?' has a 'Yes' path to 'Scanning' and a 'No' path to 'Select next channel'. 'Select next channel' leads to 'Wait for usable UCD'. The sequence continues from 'Wait for usable UCD' through 'Good upstream descriptor', 'Wait for SYNC', 'SYNC', 'Extract upstream mini-slot timing', 'Wait for map for this channel', 'Map for selected channel', 'Initial Ranging', and 'Initial Ranging Successful?'. 'Initial Ranging Successful?' has a 'Yes' path to 'Periodic Ranging' and a 'No' path that loops back to the start of the channel selection process.](7cacccfa8d5af348070fa303943955b4_img.jpg)
+
+```
+
+graph TD
+    Start([Collect UCD Messages]) --> Build[Build channel list]
+    Start --> T1[Timeout T1]
+    Build --> First[Select first channel]
+    T1 --> Scanning([Scanning])
+    Scanning --> End{End of channel list?}
+    End -- Yes --> Scanning
+    End -- No --> Next[Select next channel]
+    Next --> WaitUCD([Wait for usable UCD])
+    First --> WaitUCD
+    WaitUCD --> Good{Good upstream descriptor}
+    Good --> WaitSYNC([Wait for SYNC])
+    WaitSYNC --> SYNC{SYNC}
+    SYNC --> Extract[Extract upstream mini-slot timing]
+    Extract --> WaitMap([Wait for map for this channel])
+    WaitMap --> Map{Map for selected channel}
+    Map --> InitialRanging([Initial Ranging])
+    InitialRanging --> Success{Initial Ranging Successful?}
+    Success -- Yes --> Periodic([Periodic Ranging])
+    Success -- No --> Start
+  
+```
+
+J.122\_F11-3
+
+Flowchart for obtaining upstream parameters. The process starts with 'Collect UCD Messages', leading to 'Build channel list' and 'Timeout T1'. 'Build channel list' leads to 'Select first channel', which leads to 'Wait for usable UCD'. 'Timeout T1' leads to 'Scanning', which leads to 'End of channel list?'. 'End of channel list?' has a 'Yes' path to 'Scanning' and a 'No' path to 'Select next channel'. 'Select next channel' leads to 'Wait for usable UCD'. The sequence continues from 'Wait for usable UCD' through 'Good upstream descriptor', 'Wait for SYNC', 'SYNC', 'Extract upstream mini-slot timing', 'Wait for map for this channel', 'Map for selected channel', 'Initial Ranging', and 'Initial Ranging Successful?'. 'Initial Ranging Successful?' has a 'Yes' path to 'Periodic Ranging' and a 'No' path that loops back to the start of the channel selection process.
+
+**Figure 11-3 – Obtaining upstream parameters**
+
+The CM MUST collect all UCDs with different channel ID fields to build a set of usable channel IDs. If no channel can be found after a suitable timeout period, the CM MUST continue scanning to find another downstream channel.
+
+The CM MUST determine whether it can use the upstream channel from the channel description parameters. If the channel is not suitable, the CM MUST try other channels until it finds a usable channel.
+
+Before attempting initial ranging on an upstream, the CM categorizes the available upstreams into the following types based on the UCD for each channel:
+
+- 1) With a UCD (MAC management message type 2) offering DOCS 1.x burst descriptors only.
+- 2) With a UCD (MAC management message type 2) offering both DOCS 2.0 TDMA and DOCS 1.x burst descriptors.
+- 3) With a UCD (MAC management message type 29) for a DOCS 2.0-only upstream.
+
+The CM MUST have non-volatile storage in which channel ID of the last upstream on which the CM successfully completed registration is stored. If multiple upstreams are available, the CM MUST attempt to use the one that matches this stored channel ID. If none of the available upstreams match that stored ID, or if the CM is unable to successfully complete initial ranging on the matching channel, then the CM MUST preferentially select upstream channels in the following order. Type 3 channels are first, followed by type 2 channels, and type 1 channels are last. The CM MUST NOT begin initial ranging on a type 1 or type 2 upstream until it has allowed sufficient time, at least the UCD interval (refer to Annex B), to determine if a type 3 upstream is available. If initial ranging fails on a type 3 upstream, the CM MUST ensure that it has allowed sufficient time to detect any other type 3 upstreams that are available before moving on to a type 2 or type 1 upstream. Of course, once the CM has waited enough time to ensure that it knows about any available type 3 upstreams, it will also know about any available type 2 upstreams and it MUST try them in preference to any type 1 upstreams.
+
+If the channel is suitable, the CM MUST extract the parameters for this upstream from the UCD. If the UCD message contains a type 19 TLV, the CM MUST (except as noted below) perform a bitwise AND of its ranging class ID with the TLV 19 Value. If the result of the bitwise AND is zero, the CM MUST consider the channel unusable and try other channels until it finds a usable channel.
+
+If the CM is obtaining upstream parameters prior to performing initial ranging with an assigned SID or in preparation for ranging in response to a DCC-REQ, it MUST ignore TLV-19.
+
+If the CM is not responding to a DCC-REQ and is going to be ranging with the initialization SID and if the UCD contains a type 18 TLV, the CM performs a bitwise AND of its ranging class ID with the TLV 18 value. If the result of the bitwise AND is equal to the CM's ranging class ID, the CM MUST inhibit initial ranging and start the T17 timer. If the UCD change count in the UCD message for the channel the CM is using, is incremented while the T17 timer is active, the CM will re-inspect the TLV-18 value and re-start the T17 timer if necessary. If the T17 timer expires or the TLV-18 value is updated to permit ranging for the CMs ranging class, the CM will resume normal ranging. If the CM should undergo a lost SYNC event while waiting for T17, it MUST re-initialize the MAC. A CM that is performing initial ranging with an assigned SID MUST ignore TLV-18.
+
+After having transmitted at least one initial maintenance RNG-REQ message, the CM MUST ignore TLV-18 or TLV-19 values in any new UCD message for the channel even if the new UCD contains a ranging required TLV.
+
+The CM MUST wait for the next SYNC message and extract the upstream mini-slot timestamp from this message<sup>26</sup>. The CM then MUST wait for a bandwidth allocation map for the selected channel. It may begin transmitting upstream in accordance with the MAC operation and the bandwidth allocation mechanism.
+
+The CM MUST perform initial ranging at least once, in accordance with Figure 11-6. If initial ranging is not successful, the next channel ID is selected, and the procedure restarted from UCD extraction. When there are no more channel IDs to try, the CM MUST continue scanning to find another downstream channel.
+
+### **11.2.3 Message flows during scanning and upstream parameter acquisition**
+
+The CMTS MUST generate SYNC and UCD messages on the downstream at periodic intervals within the ranges defined in Annex B. These messages are addressed to all CMs. Refer to Figure 11-4.
+
+---
+
+<sup>26</sup> Alternatively, since the SYNC message applies to all upstream channels, the CM may have already acquired a time reference from previous SYNC messages. If so, it need not wait for a new SYNC.
+
+![](9e290fa7e4578ba0a8b8c5008c99b564_img.jpg)
+
+| CMTS                    |       |        | CM                                                                                            |
+|-------------------------|-------|--------|-----------------------------------------------------------------------------------------------|
+| Clock time to send SYNC | _____ | SYNC → |                                                                                               |
+| Clock time to send UCD  | _____ | UCD →  |                                                                                               |
+|                         |       |        |                                                                                               |
+| Clock time to send SYNC | _____ | SYNC → |                                                                                               |
+|                         |       |        | Example of a UCD cycle prior to<br>  CM power-on                                              |
+|                         |       |        |                                                                                               |
+| Clock time to send SYNC | _____ | SYNC → |                                                                                               |
+|                         |       |        |                                                                                               |
+|                         |       |        |                                                                                               |
+| Clock time to send SYNC | _____ | SYNC → |                                                                                               |
+|                         |       |        |                                                                                               |
+| Clock time to send SYNC | _____ | SYNC → |                                                                                               |
+| Clock time to send UCD  | _____ | UCD →  |                                                                                               |
+| Clock time to send SYNC | _____ | SYNC → | Power-on sequence complete                                                                    |
+| Clock time to send SYNC | _____ | SYNC → | Establish PHY synchronization and<br>  wait for UCD                                           |
+| Clock time to send SYNC | _____ | SYNC → |                                                                                               |
+| Clock time to send SYNC | _____ | SYNC → |                                                                                               |
+| Clock time to send UCD  | _____ | UCD →  | Obtain parameters for this upstream<br>  channel to use for initialization                    |
+| Clock time to send SYNC | _____ | SYNC → | Extract slot info for upstream and wait<br>  for transmit opportunity to perform<br>  ranging |
+| Clock time to send SYNC | _____ | SYNC → |                                                                                               |
+| Clock time to send MAP  | _____ | MAP →  | Start ranging process                                                                         |
+
+**Figure 11-4 – Message flows during scanning and upstream parameter acquisition**
+
+### 11.2.4 Ranging and automatic adjustments
+
+The ranging and adjustment process is fully defined in clause 8 and in the following clauses. The message sequence chart and the finite state machines on the following pages define the ranging and adjustment process which MUST be followed by compliant CMs and CMTSs. Refer to Figures 11-5 through 11-8.
+
+NOTE – MAPs are transmitted as described in clause 8.
+
+![](169044aee9e8adb39eed822364eed8aa_img.jpg)
+
+| CMTS                                                                                                                      |                           | CM                                                                                            |
+|---------------------------------------------------------------------------------------------------------------------------|---------------------------|-----------------------------------------------------------------------------------------------|
+| [Time to send the initial maintenance opportunity]                                                                        |                           |                                                                                               |
+| Send MAP containing initial maintenance information element with a broadcast/multicast service ID                         | MAP →                     |                                                                                               |
+|                                                                                                                           | ← RNG-REQ or INIT-RNG-REQ | Transmit ranging packet in contention mode with service ID parameter = 0                      |
+| [Receive recognizable ranging packet]                                                                                     |                           |                                                                                               |
+| Allocate temporary service ID                                                                                             |                           |                                                                                               |
+| Send ranging response                                                                                                     | RNG-RSP →                 |                                                                                               |
+| Add temporary service ID to poll list                                                                                     |                           | Store temporary service ID and adjust other parameters                                        |
+| [Time to send the next MAP]                                                                                               |                           |                                                                                               |
+| Send MAP with station maintenance information element or unicast initial maintenance element to modem using temporary SID | MAP →                     | Recognize own temporary service ID in map                                                     |
+|                                                                                                                           | ← RNG-REQ                 | Reply to station maintenance opportunity poll or unicast initial maintenance opportunity poll |
+| Send ranging response                                                                                                     | RNG-RSP →                 |                                                                                               |
+|                                                                                                                           |                           | Adjust local parameters                                                                       |
+| [Time to send an initial maintenance opportunity]                                                                         |                           |                                                                                               |
+| Send MAP containing initial maintenance information element with a broadcast/multicast service ID                         |                           |                                                                                               |
+| Send periodic transmit opportunity to broadcast address                                                                   | MAP →                     |                                                                                               |
+
+NOTE – The CMTS MUST allow the CM sufficient time to have processed the previous RNG-RSP (i.e., to modify the transmitter parameters) before sending the CM a specific ranging opportunity. This is defined as CM ranging response time in Annex B.
+
+**Figure 11-5 – Ranging and automatic adjustments procedure**
+
+![Flowchart for Broadcast initial ranging - CM. The process starts with 'Wait for broadcast initial ranging opportunity', leading to 'MAP with maintenance opportunity', then 'Send INIT-RNG-REQ or RNG-REQ', and 'Wait for RNG-RSP'. From 'Wait for RNG-RSP', it branches to 'RNG-RSP' (leading to 'Adjust local parameters per RNG-RSP' and 'Wait for unicast maintenance opportunity') and 'Timeout T3'. 'Timeout T3' leads to a decision 'Retries exhausted?'. If 'Y' (Yes), it leads to 'Error: re-initialize MAC'. If 'N' (No), it leads to 'Adjust local power', 'Random backoff (Note 1)', and back to 'Wait for broadcast initial ranging opportunity'. There is also a 'Timeout T2' leading to 'Error re-initialize MAC' from the initial wait state.](670a9057bbab8c7c0eb91db3a6de4d55_img.jpg)
+
+```
+
+graph TD
+    Start([Wait for broadcast initial ranging opportunity]) --> MAP{MAP with maintenance opportunity}
+    MAP --> SendReq{{Send INIT-RNG-REQ or RNG-REQ}}
+    SendReq --> WaitRSP([Wait for RNG-RSP])
+    WaitRSP --> RSP{RNG-RSP}
+    RSP --> AdjustParams[Adjust local parameters per RNG-RSP]
+    AdjustParams --> WaitUnicast([Wait for unicast maintenance opportunity])
+    WaitRSP --> T3{Timeout T3}
+    T3 --> Retries{Retries exhausted?}
+    Retries -- Y --> Error1([Error: re-initialize MAC])
+    Retries -- N --> AdjustPower[Adjust local power]
+    AdjustPower --> Backoff[Random backoff (Note 1)]
+    Backoff --> Start
+    Start --> T2{Timeout T2}
+    T2 --> Error2([Error re-initialize MAC])
+  
+```
+
+Flowchart for Broadcast initial ranging - CM. The process starts with 'Wait for broadcast initial ranging opportunity', leading to 'MAP with maintenance opportunity', then 'Send INIT-RNG-REQ or RNG-REQ', and 'Wait for RNG-RSP'. From 'Wait for RNG-RSP', it branches to 'RNG-RSP' (leading to 'Adjust local parameters per RNG-RSP' and 'Wait for unicast maintenance opportunity') and 'Timeout T3'. 'Timeout T3' leads to a decision 'Retries exhausted?'. If 'Y' (Yes), it leads to 'Error: re-initialize MAC'. If 'N' (No), it leads to 'Adjust local power', 'Random backoff (Note 1)', and back to 'Wait for broadcast initial ranging opportunity'. There is also a 'Timeout T2' leading to 'Error re-initialize MAC' from the initial wait state.
+
+J.122\_F11-6
+
+NOTE 1 – Timeout T3 may occur because the RNG-REQs from multiple modems collided. To avoid these modems repeating the loop in lockstep, a random backoff is required. This is a backoff over the ranging window specified in the MAP. T3 timeouts can also occur during multi-channel operation. On a system with multiple upstream channels, the CM MUST attempt initial ranging on every suitable upstream channel before moving to the next available downstream channel.
+
+NOTE 2 – A unicast maintenance opportunity can be either a station maintenance or a unicast initial maintenance opportunity.
+
+**Figure 11-6 – Broadcast initial ranging – CM**
+
+![Flowchart for Unicast initial ranging - CM. The process starts with 'Wait for unicast maintenance opportunity', followed by 'MAP with maintenance opportunity', 'Send RNG-REQ', 'Wait for RNG-RSP', 'RNG-RSP', 'Adjust parameters per RNG-RSP', and 'Ranging success (Note)'. If successful, it proceeds to 'Enable data transfer' and 'Establish IP layer'. If not, it checks 'RNG-REQ retries exceeded?' or 'Abort ranging from CMTS?'. If either is true, it goes to 'Error: re-initialize MAC'. Otherwise, it goes to 'Adjust transmit power' and then 'Timeout T4', which loops back to the start.](aff1234c5f34aa1533422a4de8e3707b_img.jpg)
+
+```
+
+graph TD
+    Start([Wait for unicast maintenance opportunity]) --> MAP{MAP with maintenance opportunity}
+    MAP --> SendRNGREQ{{Send RNG-REQ}}
+    SendRNGREQ --> WaitRNGRSP([Wait for RNG-RSP])
+    WaitRNGRSP --> RNGRSP{RNG-RSP}
+    RNGRSP --> AdjustParams[Adjust parameters per RNG-RSP]
+    AdjustParams --> RangingSuccess{Ranging success (Note)}
+    RangingSuccess -- Yes --> EnableData[Enable data transfer]
+    EnableData --> EstablishIP([Establish IP layer])
+    RangingSuccess -- No --> AbortRanging{Abort ranging from CMTS?}
+    AbortRanging -- Yes --> Error([Error: re-initialize MAC])
+    AbortRanging -- No --> AdjustPower[Adjust transmit power]
+    AdjustPower --> TimeoutT4{Timeout T4}
+    TimeoutT4 --> Start
+    RangingSuccess -- No --> RetriesExceeded{RNG-REQ retries exceeded?}
+    RetriesExceeded -- Yes --> Error
+    RetriesExceeded -- No --> AdjustPower
+    AdjustPower --> TimeoutT3{Timeout T3}
+    TimeoutT3 --> RetriesExceeded
+  
+```
+
+J.122\_F11-7
+
+Flowchart for Unicast initial ranging - CM. The process starts with 'Wait for unicast maintenance opportunity', followed by 'MAP with maintenance opportunity', 'Send RNG-REQ', 'Wait for RNG-RSP', 'RNG-RSP', 'Adjust parameters per RNG-RSP', and 'Ranging success (Note)'. If successful, it proceeds to 'Enable data transfer' and 'Establish IP layer'. If not, it checks 'RNG-REQ retries exceeded?' or 'Abort ranging from CMTS?'. If either is true, it goes to 'Error: re-initialize MAC'. Otherwise, it goes to 'Adjust transmit power' and then 'Timeout T4', which loops back to the start.
+
+NOTE – Ranging request is within the tolerance of the CMTS.
+
+**Figure 11-7 – Unicast initial ranging – CM**
+
+![Flowchart for Initial ranging - CMTS. The process starts with waiting for a recognizable INIT-RNG-REQ or RNG-REQ, followed by processing the RNG-REQ, checking if a SID is assigned, and then sending an RNG-RSP. It includes decision points for 'Good enough?' and 'Retries exhausted?' with various outcomes like 'Send RNG-RSP (success)', 'Send RNG-RSP (abort)', or 'Remove CM from poll list'.](193552cf6503ba3edd53a717d66779f4_img.jpg)
+
+```
+
+graph TD
+    Start([Wait for recognizable  
+INIT-RNG-REQ  
+or RNG-REQ]) --> RNGREQ1[/RNG-REQ/]
+    RNGREQ1 --> SIDAssigned{SID assigned to  
+this CM already?}
+    SIDAssigned -- No --> AssignSID[Assign temporary  
+SID]
+    AssignSID --> AddCM[Add CM to poll  
+list for future  
+maps]
+    SIDAssigned -- Yes --> ResetRetry[Reset retry count  
+in poll list for this  
+CM]
+    AddCM --> SendRNGRSPCont[Send RNG-RSP  
+(continue)]
+    ResetRetry --> SendRNGRSPCont
+    SendRNGRSPCont --> WaitPolledRNGREQ[Wait for polled  
+RNG-REQ]
+    Note2[Map will be sent per allocation  
+algorithm and pending till  
+complete (Note 2)] -.-> WaitPolledRNGREQ
+    WaitPolledRNGREQ --> RNGREQNotReceived[/RNG-REQ not  
+received/]
+    RNGREQNotReceived --> RetriesExhausted1{Retries exhausted?}
+    RetriesExhausted1 -- No --> WaitPolledRNGREQ
+    RetriesExhausted1 -- Yes --> RemoveCM1[Remove CM from  
+poll list]
+    RemoveCM1 --> WaitRecog[Wait for  
+recognizable  
+RNG-REQ]
+    WaitPolledRNGREQ --> RNGREQReceived[/RNG-REQ/]
+    RNGREQReceived --> GoodEnough{Good enough?  
+(Note 1)}
+    GoodEnough -- Yes --> SendRNGRSPSuccess[/Send  
+RNG-RSP  
+(success)/]
+    SendRNGRSPSuccess --> RemoveCM2[Remove CM from  
+poll list]
+    RemoveCM2 --> Done([Done])
+    GoodEnough -- No --> RetriesExhausted2{Retries exhausted?}
+    RetriesExhausted2 -- Yes --> SendRNGRSPAbort[/Send  
+RNG-RSP  
+(abort)/]
+    SendRNGRSPAbort --> WaitRecog
+    RetriesExhausted2 -- No --> SendRNGRSPCont2[/Send  
+RNG-RSP  
+(continue)/]
+    SendRNGRSPCont2 --> WaitPolledRNGREQ2[Wait for polled  
+RNG-REQ]
+    WaitPolledRNGREQ2 --> WaitRecog
+  
+```
+
+Flowchart for Initial ranging - CMTS. The process starts with waiting for a recognizable INIT-RNG-REQ or RNG-REQ, followed by processing the RNG-REQ, checking if a SID is assigned, and then sending an RNG-RSP. It includes decision points for 'Good enough?' and 'Retries exhausted?' with various outcomes like 'Send RNG-RSP (success)', 'Send RNG-RSP (abort)', or 'Remove CM from poll list'.
+
+NOTE 1 – "Good enough" means ranging is within the tolerable limits of the CMTS.
+
+NOTE 2 – RNG-REQ pending-till-complete was non-zero, the CMTS SHOULD hold off the station maintenance opportunity accordingly unless needed, for example, to adjust the CMs power level. If opportunities are offered prior to the pending-till-complete expiry, the "good-enough" test that follows receipt of a RNG-RSP MUST NOT judge the CMs transmit equalization until pending-till-complete expires.
+
+**Figure 11-8 – Initial ranging – CMTS**
+
+#### 11.2.4.1 Ranging parameter adjustment
+
+Adjustment of local parameters (e.g., transmit power) in a CM as a result of the receipt (or non-receipt) of an RNG-RSP is considered to be implementation-dependent with the following restrictions (refer to clause 8.3.6):
+
+- All parameters MUST be within the approved range at all times.
+- Power adjustment MUST start from the minimum value unless a valid power is available from non-volatile storage, in which case this MUST be used as a starting point.
+- Power adjustment MUST be capable of being reduced or increased by the specified amount in response to RNG-RSP messages.
+- If, during initialization, power is increased to the maximum value (without a response from the CMTS) it MUST wrap back to the minimum.
+- For multi-channel support, the CM MUST attempt initial ranging on every suitable upstream channel before moving to the next available downstream channel.
+- For multi-channel support, the CM MUST use the upstream channel ID of the range response as specified in clause 8.3.6 and in Appendix III.
+
+#### 11.2.5 Device class identification
+
+After ranging is complete and before establishing IP connectivity, the CM MAY identify itself to the CMTS for use in provisioning. Refer to Figure 11-9.
+
+![Sequence diagram for Device class identification between CMTS and CM.](e938694881f0eb809f192b1935bd79b4_img.jpg)
+
+The diagram illustrates the interaction between a CMTS (Cable Modem Termination System) and a CM (Cable Modem) for device class identification. The CMTS sends an identification request to the CM. The CM processes the request and responds with a DCI-RSP. The CMTS then continues to establish IP connectivity.
+
+```
+sequenceDiagram
+    participant CMTS
+    participant CM
+    Note left of CMTS: Send identification request to CMTS
+    CMTS->>CM: DCI-REQ
+    Note right of CM: Process request
+    CM-->>CMTS: DCI-RSP
+    Note left of CMTS: Continue to establishing IP connectivity
+```
+
+Sequence diagram for Device class identification between CMTS and CM.
+
+Figure 11-9 – Device class identification
+
+If implemented, the CM MUST use an adaptive timeout for device class identification based on binary exponential backoff, similar to that used for TFTP. Refer to clause 11.2.8 for details.
+
+#### 11.2.6 Establish IP connectivity
+
+At this point, the CM MUST invoke DHCP mechanisms [RFC 2131] in order to obtain an IP address and any other parameters needed to establish IP connectivity (refer to Annex D). The DHCP response MUST contain the name of a file that contains further configuration parameters. Refer to Figure 11-10.
+
+![Sequence diagram showing the DHCP process between a CM and a DHCP server. The CM sends a DHCP discover, the DHCP server checks the MAC address and responds with a DHCP offer. The CM then chooses a server and sends a DHCP request, which the server processes and responds with a DHCP response. Finally, the CM sets up IP parameters.](d81c8e2a793e1c09694427481b915762_img.jpg)
+
+```
+
+sequenceDiagram
+    participant CM
+    participant DHCP
+    Note left of CM: Send DHCP request to broadcast address
+    CM->>DHCP: DHCP discover
+    Note right of DHCP: Check CM MAC address and respond
+    DHCP-->>CM: DHCP offer
+    Note left of CM: Choose server
+    CM->>DHCP: DHCP request
+    Note right of DHCP: Process request
+    DHCP-->>CM: DHCP response
+    Note left of CM: Set up IP parameters from DHCP response
+
+```
+
+Sequence diagram showing the DHCP process between a CM and a DHCP server. The CM sends a DHCP discover, the DHCP server checks the MAC address and responds with a DHCP offer. The CM then chooses a server and sends a DHCP request, which the server processes and responds with a DHCP response. Finally, the CM sets up IP parameters.
+
+**Figure 11-10 – Establishing IP connectivity**
+
+As required in [RFC 2131], the CM MUST adopt a retransmission strategy that incorporates a randomized exponential backoff algorithm to determine the delay between retransmissions. The backoff algorithm SHOULD use a backoff start value of 4 seconds, a backoff end value of 64 seconds and randomized value of  $\pm 1$  second. The CM MUST limit the number of retransmissions. The CM SHOULD limit the number of retransmissions (excluding the first transmission) to a maximum retries value of 5 but MAY implement less than the maximum retries value. The CM SHOULD also implement a different retransmission strategy for the RENEWING and REBINDING states, as recommended in [RFC 2131], which is based on one-half of the remaining lease time. Upon failure of obtaining or rebinding an IP address, the CM MUST attempt to establish communication on another upstream channel (see clause 11.2.2) or resume scanning to find another downstream channel (see clause 11.2.1).
+
+### 11.2.7 Establish time of day
+
+The CM and CMTS need to have the current date and time. This is required for time-stamping logged events which can be retrieved by the management system. This need not be authenticated and need only be accurate to the nearest second.
+
+The protocol by which the time of day MUST be retrieved is defined in [RFC 868]. Refer to Figure 11-11. The request and response MUST be transferred using UDP. The time retrieved from the server (UTC) MUST be combined with the time offset received from the DHCP response to create the current local time.
+
+![Sequence diagram showing the time of day protocol between a CM and a Time server. The CM sends a time of day request, the server processes it and responds with a time of day response. Finally, the CM sets up/corrects the time of day.](3d6dbebf94a27041f730a0dcc7e3dfda_img.jpg)
+
+```
+
+sequenceDiagram
+    participant CM
+    participant Time server
+    Note left of CM: Send request to time server
+    CM->>Time server: Time of day request
+    Note right of Time server: Process request
+    Time server-->>CM: Time of day response
+    Note left of CM: Set up/correct time of day from response
+
+```
+
+Sequence diagram showing the time of day protocol between a CM and a Time server. The CM sends a time of day request, the server processes it and responds with a time of day response. Finally, the CM sets up/corrects the time of day.
+
+**Figure 11-11 – Establishing time of day**
+
+The DHCP server may offer a CM multiple time of day server IP addresses to attempt. The CM MUST attempt all time of day servers included in the DHCP offer until local time is established.
+
+Successfully acquiring the time of day is not mandatory for a successful registration, but it is necessary for ongoing operation. If a CM is unable to establish time of day before registration it MUST log the failure, generate an alert to management facilities, then proceed to an operational state and retry periodically.
+
+The specific timeout for time of day Requests is implementation-dependent. However, for each server defined the CM MUST NOT exceed more than 3 time of day requests in any 5-minute period. At minimum, the CM MUST issue at least 1 time of day request per 5-minute period for each server specified until local time is established.
+
+#### **11.2.8 Transfer operational parameters**
+
+After DHCP is successful, the modem MUST download the parameter file using TFTP, as shown in Figure 11-12. The TFTP configuration parameter server is specified by the "siaddr" field of the DHCP response. The CM MUST use an adaptive timeout for TFTP based on binary exponential backoff. Refer to [RFC 1123] and [RFC 2349].
+
+![Flowchart for Registration - CM process. The process starts with 'Time of day request' leading to 'Wait for time of day response'. A note indicates 'Time of day retries are asynchronous with registration'. The flow then splits into 'Time of day response' and 'Timeout'. Both lead to 'Request config. file'. From 'Request config. file', the flow goes to 'Wait for successful TFTP'. This leads to 'Config. file received' and 'Timeout'. 'Timeout' leads to 'Increment retry counter'. 'Config. file received' leads to a decision 'Mandatory items present?'. If 'No', it leads to 'Increment retry counter'. If 'Yes', it leads to 'CM MIC valid?'. If 'No', it leads to 'Increment retry counter'. If 'Yes', it leads to 'TLV type 11 errors?'. If 'Yes', it leads to 'Increment retry counter'. If 'No', it leads to 'Acquire operational parameters', which leads to 'Send REG-REQ', which leads to 'Wait for REG-RSP'. A decision 'Retries exceeded?' is also present. If 'No', it loops back to 'Request config. file'. If 'Yes', it leads to 'Scan for downstream channel'.](3747d48bc2656121be0dff7dbcb32fca_img.jpg)
+
+```
+
+graph TD
+    A[/Time of day request/] --> B([Wait for time of day response])
+    B --> C[/Time of day response/]
+    B --> D[/Timeout/]
+    C --> E[/Request config. file/]
+    D --> E
+    E --> F([Wait for successful TFTP])
+    F --> G[/Config. file received/]
+    F --> H[/Timeout/]
+    H --> I[Increment retry counter]
+    G --> J{Mandatory items present?}
+    J -- No --> I
+    J -- Yes --> K{CM MIC valid?}
+    K -- No --> I
+    K -- Yes --> L{TLV type 11 errors?}
+    L -- Yes --> I
+    L -- No --> M[Acquire operational parameters]
+    M --> N[/Send REG-REQ/]
+    N --> O([Wait for REG-RSP])
+    I --> P{Retries exceeded?}
+    P -- No --> E
+    P -- Yes --> Q([Scan for downstream channel])
+    R[Time of day retries are asynchronous with registration]
+  
+```
+
+Flowchart for Registration - CM process. The process starts with 'Time of day request' leading to 'Wait for time of day response'. A note indicates 'Time of day retries are asynchronous with registration'. The flow then splits into 'Time of day response' and 'Timeout'. Both lead to 'Request config. file'. From 'Request config. file', the flow goes to 'Wait for successful TFTP'. This leads to 'Config. file received' and 'Timeout'. 'Timeout' leads to 'Increment retry counter'. 'Config. file received' leads to a decision 'Mandatory items present?'. If 'No', it leads to 'Increment retry counter'. If 'Yes', it leads to 'CM MIC valid?'. If 'No', it leads to 'Increment retry counter'. If 'Yes', it leads to 'TLV type 11 errors?'. If 'Yes', it leads to 'Increment retry counter'. If 'No', it leads to 'Acquire operational parameters', which leads to 'Send REG-REQ', which leads to 'Wait for REG-RSP'. A decision 'Retries exceeded?' is also present. If 'No', it loops back to 'Request config. file'. If 'Yes', it leads to 'Scan for downstream channel'.
+
+**Figure 11-12 – Registration – CM**
+
+The parameter fields required in the DHCP response, and the format and content of the configuration file **MUST** be as defined in Annex D. Note that these fields are the minimum required for interoperability.
+
+If a modem downloads a configuration file containing an upstream channel ID configuration setting (clause C.1.1.2) different from what the modem is currently using, the modem **MUST NOT** send a registration request message to the CMTS. Likewise, if a modem downloads a configuration file containing a single downstream channel frequency (clause C.1.1.21.1.2) and/or downstream frequency range (clause C.1.1.21.2) that does not include the downstream frequency the modem is currently using, or a downstream frequency configuration setting (clause C.1.1.1) different from what the modem is currently using and no downstream channel list, the modem **MUST NOT** send a
+
+registration request message to the CMTS. In either case, the modem MUST redo initial ranging using the configured upstream channel and/or downstream frequency per clause 8.3.6.3.
+
+If a modem downloads a configuration file containing the enable 2.0 mode TLV set to disable (see clause C.1.1.19), then it MUST NOT operate in 2.0 mode until it registers again and downloads a configuration file which does not have this TLV set to disable. This is true no matter what type of upstream the CM is using at the time it is attempting registration. If it is using a type 3 channel (as described in clause 11.2.2), it MUST NOT send a registration request message to the CMTS. The modem MUST redo initial ranging using a type 1 or type 2 channel. If no such upstream channel is available (or if the modem is unable to range successfully on one) the modem MUST scan for a new downstream, at which point 2.0 mode is no longer disabled. If the modem downloads a configuration file that does not disable 2.0 mode, then, regardless of what kind of upstream it is using at the time of registration, it will continue to operate with 2.0 mode enabled until it is no longer registered. This means that if a modem registers on a type 1 channel with a configuration file that enables 2.0 mode operation, and then ends up on a type 2 or type 3 upstream without going through re-registration, the CM would immediately start operating in 2.0 mode.
+
+## 11.2.9 Registration
+
+A CM MUST be authorized to forward traffic into the network once it is initialized and configured. The CM is authorized to forward traffic into the network via registration. To register with a CMTS, the CM MUST forward its configured class of service and any other operational parameters in the configuration file (refer to clause 8.3.7) to the CMTS as part of a registration request. The CM MUST perform the following operations before registration (refer to Figure 11-12):
+
+- Check configuration file mandatory items (refer to clause D.2.2). The CM MUST reject a configuration file if it lacks any mandatory items.
+- Calculate a MIC per clause D.2.3.1 and compare it to the CM MIC included in the configuration file. If the MIC is invalid, the CM MUST reject the configuration file.
+- If the configuration file contains TLV-11 encoding, the CM MUST follow the configuration process defined in clause 3.4 of [DOCS5]. The CM MUST reject a configuration file in the case of TLV-11 processing failure.
+
+Figure 11-12 shows the procedure that MUST be followed by the CM.
+
+The configuration parameters downloaded to the CM MUST include a network access control object (see clause C.1.1.3). If this is set to "no forwarding," the CM MUST NOT forward data from attached CPE to the network, yet the CM MUST respond to network management requests. This allows the CM to be configured in a mode in which it is manageable but will not forward data.
+
+Once the CM has sent a registration request to the CMTS, it MUST wait for a registration response to authorize it to forward traffic to the network. Figure 11-13 shows the waiting procedure that MUST be followed by the CM.
+
+![Flowchart titled 'Wait for Reg Rsp' showing the registration response process for a CM. It starts with 'Wait for Reg Rsp', leading to 'Timeout T6' and 'REG-RSP'. 'Timeout T6' leads to 'Retries exhausted?'. If 'No', it goes to 'Send REG-REQ' and then 'Wait for REG-RSP'. If 'Yes', it goes to 'Error: Re-initialize MAC'. 'REG-RSP' leads to 'Response = ok?'. If 'No', it goes to 'Implementation Dependent'. If 'Yes', it leads to 'CM supports all parameters in REG-RSP?'. If 'No', it goes to 'Send REG-ACK with error sets' and then to 'Implementation Dependent'. If 'Yes', it goes to 'Setup Service Flows & Activate Operational Parameters', then 'Send REG-ACK'. 'Send REG-ACK' leads to 'DOCS 2.0 enabled AND Type 2 channel?'. If 'Yes', it goes to 'Switch to DOCS 2.0 mode' and then to 'Operational'. If 'No', it goes to 'Operational'. 'Operational' leads to 'REG-RSP'. 'Switch to DOCS 2.0 mode' also leads to 'Operational'. 'Switch to DOCS 1.1 mode' leads to 'DOCS 2.0 enabled AND Type 2 channel?'. If 'Yes', it goes to 'Switch to DOCS 2.0 mode' and then to 'Operational'. If 'No', it goes to 'REG-RSP'.](b35608e925cb6a7c0aa0db30d2db9d66_img.jpg)
+
+```
+
+graph TD
+    Start([Wait for Reg Rsp]) --> T6[Timeout T6]
+    Start --> REG_RSP[REG-RSP]
+    T6 --> Retries{Retries exhausted?}
+    Retries -- No --> Send_REG_REQ[Send REG-REQ]
+    Send_REG_REQ --> Wait_REG_RSP[Wait for REG-RSP]
+    Retries -- Yes --> Error[Error: Re-initialize MAC]
+    REG_RSP --> ResponseOk{Response = ok?}
+    ResponseOk -- No --> ImplDep[Implementation Dependent]
+    ResponseOk -- Yes --> CMParams{CM supports all parameters in REG-RSP?}
+    CMParams -- No --> Send_REG_ACK_Err[Send REG-ACK with error sets]
+    Send_REG_ACK_Err --> ImplDep
+    CMParams -- Yes --> Setup[Setup Service Flows & Activate Operational Parameters]
+    Setup --> Send_REG_ACK[Send REG-ACK]
+    Send_REG_ACK --> DOCS20_1{DOCS 2.0 enabled AND Type 2 channel?}
+    DOCS20_1 -- Yes --> Switch20[Switch to DOCS 2.0 mode]
+    DOCS20_1 -- No --> Operational([Operational])
+    Switch20 --> Operational
+    Operational --> REG_RSP_2[REG-RSP]
+    Switch20 --> Switch11[Switch to DOCS 1.1 mode]
+    Switch11 --> DOCS20_2{DOCS 2.0 enabled AND Type 2 channel?}
+    DOCS20_2 -- Yes --> Switch20
+    DOCS20_2 -- No --> REG_RSP_2
+  
+```
+
+Flowchart titled 'Wait for Reg Rsp' showing the registration response process for a CM. It starts with 'Wait for Reg Rsp', leading to 'Timeout T6' and 'REG-RSP'. 'Timeout T6' leads to 'Retries exhausted?'. If 'No', it goes to 'Send REG-REQ' and then 'Wait for REG-RSP'. If 'Yes', it goes to 'Error: Re-initialize MAC'. 'REG-RSP' leads to 'Response = ok?'. If 'No', it goes to 'Implementation Dependent'. If 'Yes', it leads to 'CM supports all parameters in REG-RSP?'. If 'No', it goes to 'Send REG-ACK with error sets' and then to 'Implementation Dependent'. If 'Yes', it goes to 'Setup Service Flows & Activate Operational Parameters', then 'Send REG-ACK'. 'Send REG-ACK' leads to 'DOCS 2.0 enabled AND Type 2 channel?'. If 'Yes', it goes to 'Switch to DOCS 2.0 mode' and then to 'Operational'. If 'No', it goes to 'Operational'. 'Operational' leads to 'REG-RSP'. 'Switch to DOCS 2.0 mode' also leads to 'Operational'. 'Switch to DOCS 1.1 mode' leads to 'DOCS 2.0 enabled AND Type 2 channel?'. If 'Yes', it goes to 'Switch to DOCS 2.0 mode' and then to 'Operational'. If 'No', it goes to 'REG-RSP'.
+
+**Figure 11-13 – Wait for registration response – CM<sup>27</sup>**
+
+NOTE – In Figures 11-12 and 11-13, a type 2 upstream supports both DOCS 1.1 and DOCS 2.0 TDMA bursts (see 11.2.2). On such an upstream, it is necessary that the CMTS knows whether the CM has calculated a request to transmit data based on the DOCS 2.0 TDMA data IUCs (9, 10) or on the DOCS 1.x IUCs (5, 6). On these upstreams, the CM calculates all requests up to and including the request to transmit the REG-ACK based on the DOCS 1.x IUCs. If the CM is enabled to operate in 2.0 mode (see clause C.1.1.19), all requests to transmit data on such an upstream, subsequent to the transmission of the REG-ACK, are calculated based on the DOCS 2.0 TDMA data IUCs. If the CMTS indicates that it did not receive the REG-ACK by retransmitting the REG-RSP, a CM using such an upstream MUST revert to the DOCS 1.x data IUCs to request bandwidth for retransmitting the REG-ACK.
+
+<sup>27</sup> Refer to clause 11.2.2 for channel type definitions.
+
+The CMTS MUST perform the following operations to confirm the CM authorization (refer to Figures 11-14 and 11-15):
+
+- Calculate a MIC per clause D.3.1 and compare it to the CMTS MIC included in the registration request. If the MIC is invalid, the CMTS MUST respond with an authentication failure.
+- If present, check the TFTP server timestamp field. If the CMTS detects that the time is different from its local time by more than CM configuration processing time (refer to Annex B), the CMTS MUST indicate authentication failure in the REG-RSP. The CMTS SHOULD also make a log entry stating the CM MAC address from the message.
+- If present, check the TFTP server provisioned modem address field. If the provisioned modem address does not match the requesting modem's actual address, the CMTS MUST indicate authentication failure in the REG-RSP. The CMTS SHOULD also make a log entry stating the CM MAC address from the message.
+- If the registration request contains DOCS 1.0 class-of-service encodings, verify the availability of the class(es) of service requested. If unable to provide the class(es) of service, the CMTS MUST respond with a class-of-service failure and the appropriate service not available response code(s) (refer to clause C.1.3.4).
+- If the registration request contains service flow encodings, verify the availability of the quality of service requested in the provisioned service flow(s). If unable to provide the service flow(s), the CMTS MUST respond with either a reject-temporary or a reject-permanent (see clause C.4) and the appropriate service flow response(s).
+- If the registration request contains DOCS 1.0 class-of-service encodings and service flow encodings, the CMTS MUST respond with a class-of-service failure and a service not available response code set to 'reject-permanent' for all DOCS 1.0 classes and service flows requested.
+- Verify the availability of any modem capabilities requested. If unable or unwilling to provide the modem capability requested, the CMTS MUST turn that modem capability 'off' (refer to clause 8.3.8.1.1).
+- Assign a service flow ID for each class of service supported.
+- Reply to the modem in a registration response.
+- If the registration request contains service flow encoding and the REG-RSP is sent with a confirmation code of ok (0), the CMTS MUST wait for a registration acknowledgment as shown in Figure 11-14. If the registration request contains DOCS 1.0 class-of-service encodings, the CMTS MUST NOT wait for a registration acknowledgment.
+- In a channel that supports both DOCS 1.x and DOCS 2.0 TDMA burst types (see clause 11.2), the CMTS MUST change the operational state of the DOCS 2.0 enabled CM (see clause C.1.1.19) to DOCS 2.0 TDMA after the registration acknowledgement message is received from the CM.
+- If timer T9 expires, the CMTS MUST both de-assign the temporary SID from that CM and make some provision for aging out that SID.
+
+![Flowchart for Registration - CMTS process. The process starts with 'Waiting for REG-REQ', followed by 'REG-REQ', 'Stop T9', and 'Calculate MIC over REG-REQ'. It then enters a series of decision diamonds: 'CMTS MIC Valid?', 'TFTP server IP and/or timestamp valid?', 'Can the requested service(s) ever be supported?', and 'Can the requested service(s) currently be supported?'. Each 'No' branch leads to a 'Send REG-RSP' box with specific error reasons, all of which lead to 'Wait for REG-REQ'. The 'Yes' branches continue the process to 'Set modem capabilities supported in REG-RSP', 'Create requested services', and 'Send REG-RSP with response = OK', ending at 'Waiting for REG-ACK'. A label 'J.122_F11-14' is present near the bottom right of the flow.](8dd299498fe4924af215a1d179688e11_img.jpg)
+
+```
+
+graph TD
+    Start([Waiting for REG-REQ]) --> REG-REQ[REG-REQ]
+    REG-REQ --> StopT9[Stop T9]
+    StopT9 --> CalcMIC[Calculate MIC over REG-REQ]
+    CalcMIC --> MICValid{CMTS MIC Valid?}
+    MICValid -- No --> RSP1[Send REG-RSP with response = authentication failure]
+    MICValid -- Yes --> TFTPValid{TFTP server IP and/or timestamp valid?}
+    TFTPValid -- No --> RSP2[Send REG-RSP with response = authentication failure and should log failure]
+    TFTPValid -- Yes --> ServiceEver{Can the requested service(s) ever be supported?}
+    ServiceEver -- No --> RSP3[Send REG-RSP with response = class of service failure and service not available = reason permanent]
+    ServiceEver -- Yes --> ServiceNow{Can the requested service(s) currently be supported?}
+    ServiceNow -- No --> RSP4[Send REG-RSP with response = class of service failure and service not available = reason temporary]
+    RSP1 --> WaitREQ([Wait for REG-REQ])
+    RSP2 --> WaitREQ
+    RSP3 --> WaitREQ
+    RSP4 --> WaitREQ
+    ServiceNow -- Yes --> SetCapabilities[Set modem capabilities supported in REG-RSP]
+    SetCapabilities --> CreateServices[Create requested services]
+    CreateServices --> RSP5[Send REG-RSP with response = OK]
+    RSP5 --> WaitACK([Waiting for REG-ACK])
+    J122_F11_14[J.122_F11-14]
+  
+```
+
+Flowchart for Registration - CMTS process. The process starts with 'Waiting for REG-REQ', followed by 'REG-REQ', 'Stop T9', and 'Calculate MIC over REG-REQ'. It then enters a series of decision diamonds: 'CMTS MIC Valid?', 'TFTP server IP and/or timestamp valid?', 'Can the requested service(s) ever be supported?', and 'Can the requested service(s) currently be supported?'. Each 'No' branch leads to a 'Send REG-RSP' box with specific error reasons, all of which lead to 'Wait for REG-REQ'. The 'Yes' branches continue the process to 'Set modem capabilities supported in REG-RSP', 'Create requested services', and 'Send REG-RSP with response = OK', ending at 'Waiting for REG-ACK'. A label 'J.122\_F11-14' is present near the bottom right of the flow.
+
+**Figure 11-14 – Registration – CMTS**
+
+![Flowchart for Registration acknowledgment – CMTS. The process starts with 'Waiting for REG-ACK', leading to 'REG-ACK' or 'Timeout T6'. 'REG-ACK' leads to a decision 'REG-ACK contains error sets?'. If 'No', it leads to 'Adv. PHY activated AND Type 2 channel?'. If 'Yes', it leads to 'Retries Exhausted?'. 'Timeout T6' also leads to 'Retries Exhausted?'. From 'Retries Exhausted?', 'No' leads to 'Send REG-RSP with response = OK' and 'Yes' leads to 'Destroy Services'. Both 'Send REG-RSP with response = OK' and 'Destroy Services' lead to 'Waiting for Reg-Req'. 'Adv. PHY activated AND Type 2 channel?' 'Yes' leads to 'Switch CM operational state to Adv PHY' and 'No' leads to 'Operational'. Both 'Switch CM operational state to Adv PHY' and 'Operational' lead to 'Operational'.](2650ae98f0e6dda48ae00a936ddea0ef_img.jpg)
+
+```
+
+graph TD
+    Start([Waiting for REG-ACK]) --> REG_ACK[REG-ACK]
+    Start --> Timeout[Timeout T6]
+    REG_ACK --> ErrorSets{REG-ACK contains error sets?}
+    ErrorSets -- No --> AdvPHY{Adv. PHY activated AND Type 2 channel?}
+    ErrorSets -- Yes --> Retries{Retries Exhausted?}
+    Timeout --> Retries
+    Retries -- No --> SendRSP{{Send REG-RSP with response = OK}}
+    Retries -- Yes --> Destroy[Destroy Services]
+    SendRSP --> WaitingRegReq([Waiting for Reg-Req])
+    Destroy --> WaitingRegReq
+    AdvPHY -- No --> Operational([Operational])
+    AdvPHY -- Yes --> SwitchState[Switch CM operational state to Adv PHY]
+    SwitchState --> Operational
+  
+```
+
+Flowchart for Registration acknowledgment – CMTS. The process starts with 'Waiting for REG-ACK', leading to 'REG-ACK' or 'Timeout T6'. 'REG-ACK' leads to a decision 'REG-ACK contains error sets?'. If 'No', it leads to 'Adv. PHY activated AND Type 2 channel?'. If 'Yes', it leads to 'Retries Exhausted?'. 'Timeout T6' also leads to 'Retries Exhausted?'. From 'Retries Exhausted?', 'No' leads to 'Send REG-RSP with response = OK' and 'Yes' leads to 'Destroy Services'. Both 'Send REG-RSP with response = OK' and 'Destroy Services' lead to 'Waiting for Reg-Req'. 'Adv. PHY activated AND Type 2 channel?' 'Yes' leads to 'Switch CM operational state to Adv PHY' and 'No' leads to 'Operational'. Both 'Switch CM operational state to Adv PHY' and 'Operational' lead to 'Operational'.
+
+J.122\_F11-15
+
+**Figure 11-15 – Registration acknowledgment – CMTS**
+
+### 11.2.10 Baseline privacy initialization
+
+Following registration, if the CM is provisioned to run baseline privacy, the CM MUST initialize baseline privacy operations as described in [DOCS8]. A CM is provisioned to run baseline privacy if the privacy enable TLV (see clause C.1.1.16) in the DOCS 1.1 style configuration file is explicitly/implicitly set to enable or the baseline privacy configuration setting (see clause C.3.2) is contained in the DOCS 1.0 style configuration file as specified in clauses A.1.1 and C.2 of the BPI+ Recommendation [DOCS8]. Note that the secure software download is required regardless of whether the CM is provisioned to run baseline privacy or not as specified in Appendix D of the BPI+ Recommendation [DOCS8].
+
+When assigning provisioned SFIDs on receiving a registration request, the CMTS may re-use the temporary SID, assigning it to one of the service flows requested. If so, it MUST continue to allow initialization messages on that SID, since the registration response could be lost in transit. If the CMTS assigns all-new SIDs for class-of-service provisioning, it MUST age out the temporary SID. The aging-out MUST allow sufficient time to complete the registration process in case the registration response is lost in transit.
+
+### 11.2.11 Service IDs during CM initialization
+
+After completion of the registration process (see clause 11.2.9), the CM will have been assigned service flow IDs (SFIDs) to match its provisioning. However, the CM must complete a number of protocol transactions prior to that time (e.g., ranging, DHCP, etc.), and requires a temporary service ID in order to complete those steps.
+
+On reception of an initial ranging request, the CMTS MUST allocate a temporary SID and assign it to the CM for initialization use. The CMTS MAY monitor use of this SID and restrict traffic to that needed for initialization. It MUST inform the CM of this assignment in the ranging response.
+
+The temporary SID assigned by the CMTS MUST be in the unicast SID space (see clause 9.1.2). DOCSIS 2.0 CMs MUST support the capability to transmit unicast traffic on the expanded SID space (see clause C.1.3.1.3). If a CM supports the above capability the CMTS MAY assign SID numbers from the expanded unicast SID space in the registration response.
+
+On receiving a ranging response addressed to it, the CM MUST use the assigned temporary SID for further initialization transmission requests until the registration response is received.
+
+On receiving a ranging response instruction to move to a new downstream frequency and/or upstream channel ID, the CM MUST consider any previously assigned temporary SID to be de-assigned, and must obtain a new temporary SID via initial ranging.
+
+It is possible that the ranging response may be lost after transmission by the CMTS. The CM MUST recover by timing out and re-issuing its initial ranging request. Since the CM is uniquely identified by the source MAC address in the ranging request, the CMTS MAY immediately reuse the temporary SID previously assigned. If the CMTS assigns a new temporary SID, it MUST make some provision for aging out the old SID that went unused (see clause 8.3.8).
+
+When assigning provisioned SFIDs on receiving a registration request, the CMTS may reuse the temporary SID, assigning it to one of the service flows requested. If so, it MUST continue to allow initialization messages on that SID, since the registration response could be lost in transit. If the CMTS assigns all-new SIDs for class-of-service provisioning, it MUST age out the temporary SID. The aging-out MUST allow sufficient time to complete the registration process in case the registration response is lost in transit.
+
+## **11.2.12 Multiple-channel support**
+
+In the event that more than one downstream signal is present in the system, the CM MUST operate using the first valid downstream signal that it encounters when scanning. It will be instructed via the parameters in the configuration file (see Annex C) to shift operation to different downstream and/or upstream frequencies if necessary.
+
+Both upstream and downstream channels MUST be identified where required in MAC management messages using channel identifiers.
+
+## **11.3 Standard operation**
+
+### **11.3.1 Periodic signal level adjustment**
+
+The CMTS MUST provide each CM a periodic ranging opportunity at least once every T4 seconds. The CMTS MUST send out periodic ranging opportunities at an interval sufficiently shorter than T4 that a MAP could be missed without the CM timing out. The size of this "subinterval" is CMTS-dependent.
+
+The CM MUST re-initialize its MAC after T4 seconds have elapsed without receiving a periodic ranging opportunity.
+
+Remote RF signal level adjustment at the CM is performed through a periodic ranging function using the RNG-REQ and RNG-RSP MAC messages. This is similar to initial ranging and is shown in Figures 11-16 and 11-17. On receiving a RNG-RSP, the CM MUST NOT transmit until the RF signal has been adjusted in accordance with the RNG-RSP and has stabilized (refer to clause 6). The CM MUST NOT transmit anything other than RNG-REQs, if it has been suspended by receiving a RNG-RSP with a ranging state of CONTINUE, until such time as it receives a RNG-RSP with a ranging state of SUCCESS. When operating in 1.x mode, the CM should continue
+
+normal operation and MUST NOT suspend on-going data transmission if it receives a RNG-RSP with a ranging status of CONTINUE.
+
+The CMTS SHOULD NOT send a ranging status of CONTINUE in a RNG-RSP to any CMs in 2.0 mode unless the ranging parameters measured on the corresponding RNG-REQ are insufficient for the CMTS to guarantee proper reception of all burst types available to that CM. Additionally, upon sending a RNG-RSP with ranging status of CONTINUE to a CM in 2.0 mode, the CMTS SHOULD schedule another periodic ranging opportunity for the CM quickly so that the CM can return to a ranging status of SUCCESS as quickly as possible.
+
+As described in clause 11.2.1, during normal operation in the S-CDMA mode, if a CM temporarily loses synchronization to the downstream signal, it is required to perform a ranging process before returning to normal operation. To facilitate this recovery, if the CMTS does not receive a RNG-REQ message from a CM during a station maintenance interval, the CMTS MAY schedule unicast initial maintenance opportunities, or it MAY temporarily reduce the time between unicast spreader-off station maintenance opportunities.
+
+![Flowchart for Periodic ranging - CMTS. The process starts with adding a CM to a poll list on a periodic timer. It then enters a loop waiting for a polled RNG-REQ. If not received, it checks if retries are exhausted. If yes, it sends an abort response, removes the CM from the poll list, destroys associated SIDs, and ends. If no, it loops back. If received, it checks if it's 'Good enough'. If yes, it sends a success response, removes the CM from the poll list, and ends. If no, it checks if retries are exhausted. If yes, it sends an abort response, removes the CM from the poll list, destroys associated SIDs, and ends. If no, it sends a continue response and loops back to waiting for a polled RNG-REQ. A note indicates that MAPs will be sent per allocation algorithm and pending till complete.](65c3a00aa9457af841a9e548ef5a5c30_img.jpg)
+
+```
+
+graph TD
+    Start[On periodic timer add CM to poll list for future MAPs] --> WaitRNG[Wait for polled RNG-REQ]
+    Note2[MAP will be sent per allocation algorithm and pending till complete Note 2] -.-> WaitRNG
+    WaitRNG --> NotReceived{RNG-REQ not received}
+    NotReceived --> RetriesExhausted1{Retries exhausted?}
+    RetriesExhausted1 -- No --> WaitRNG
+    RetriesExhausted1 -- Yes --> AbortRSP[Send RNG-RSP abort]
+    AbortRSP --> RemoveCM1[Remove CM from poll list]
+    RemoveCM1 --> DestroySIDs[Destroy SIDs associated with this CM]
+    DestroySIDs --> Done1([Done])
+    WaitRNG --> Received{RNG-REQ}
+    Received --> GoodEnough{Good enough? Note 1}
+    GoodEnough -- Yes --> SuccessRSP[Send RNG-RSP success]
+    SuccessRSP --> RemoveCM2[Remove CM from poll list]
+    RemoveCM2 --> Done2([Done])
+    GoodEnough -- No --> RetriesExhausted2{Retries exhausted?}
+    RetriesExhausted2 -- Yes --> AbortRSP
+    RetriesExhausted2 -- No --> ContinueRSP[Send RNG-RSP continue]
+    ContinueRSP --> WaitRNG
+  
+```
+
+J.122\_F11-16
+
+Flowchart for Periodic ranging - CMTS. The process starts with adding a CM to a poll list on a periodic timer. It then enters a loop waiting for a polled RNG-REQ. If not received, it checks if retries are exhausted. If yes, it sends an abort response, removes the CM from the poll list, destroys associated SIDs, and ends. If no, it loops back. If received, it checks if it's 'Good enough'. If yes, it sends a success response, removes the CM from the poll list, and ends. If no, it checks if retries are exhausted. If yes, it sends an abort response, removes the CM from the poll list, destroys associated SIDs, and ends. If no, it sends a continue response and loops back to waiting for a polled RNG-REQ. A note indicates that MAPs will be sent per allocation algorithm and pending till complete.
+
+NOTE 1 – "Good enough" means ranging request is within the tolerance limits of the CMTS for power and transmit equalization (if supported).  
+ NOTE 2 – RGN-REQ pending-till-complete was non-zero, the CMTS SHOULD hold off the station maintenance opportunity accordingly unless needed, for example, to adjust the CM's power level. If opportunities are offered prior to the pending-till-complete expiry, the "good-enough" test that follows receipt of RGN-RSP MUST NOT judge the CM's transmit equalization until pending-till-complete expires.
+
+**Figure 11-16 – Periodic ranging – CMTS**
+
+![Flowchart for Periodic ranging - CM view. The process starts at 'Operational' and branches into 'Unicast maintenance opportunity', 'Timeout T3', 'Timeout T4', and 'RNG-RSP'. The 'Unicast maintenance opportunity' path leads to 'Start T4 timer', 'Send RNG-REQ', 'Increment RNG-REQ retry counter', and 'Start T3 timer'. The 'RNG-REQ' path leads to a decision 'RNG-REQ retries exceeded?'. If 'Yes', it leads to 'Error: re-initialize MAC'. If 'No', it loops back to 'Start T3 timer'. The 'Timeout T3' path leads to the 'RNG-REQ retries exceeded?' decision. The 'Timeout T4' path leads to 'Abort ranging from CMTS?'. The 'RNG-RSP' path leads to 'T3 timer started?'. If 'Yes', it leads to 'Reset RNG-REQ retry counter; clear T3 timer'. If 'No', it leads to 'Abort ranging from CMTS?'. From 'Abort ranging from CMTS?', if 'Yes', it leads to 'Error: re-initialize MAC'. If 'No', it leads to 'Success ranging from CMTS?'. If 'Yes', it leads to 'Clear transmission suspend' and then 'Adjust local parameters per RNG-RSP'. If 'No', it leads to 'Suspend transmission of everything except RNG-REQs' and then 'Adjust local parameters per RNG-RSP'. Both 'Adjust local parameters per RNG-RSP' and 'Error: re-initialize MAC' lead back to 'Operational'.](5d84c9d0a467de80ab909d637ecd5639_img.jpg)
+
+```
+
+graph TD
+    Operational([Operational]) --> Unicast{Unicast maintenance opportunity}
+    Operational --> T3{Timeout T3}
+    Operational --> T4{Timeout T4}
+    Operational --> RNGRSP{RNG-RSP}
+    
+    Unicast --> StartT4[Start T4 timer]
+    StartT4 --> SendRNGREQ[/Send RNG-REQ/]
+    SendRNGREQ --> IncrementRNGREQ[Increment RNG-REQ retry counter]
+    IncrementRNGREQ --> StartT3[Start T3 timer]
+    StartT3 --> Operational
+    
+    T3 --> RetriesExceeded{RNG-REQ retries exceeded?}
+    RetriesExceeded -- Yes --> Error([Error: re-initialize MAC])
+    RetriesExceeded -- No --> StartT3
+    
+    T4 --> AbortRanging{Abort ranging from CMTS?}
+    AbortRanging -- Yes --> Error
+    AbortRanging -- No --> SuccessRanging{Success ranging from CMTS?}
+    
+    RNGRSP --> T3Started{T3 timer started?}
+    T3Started -- Yes --> ResetRNGREQ[Reset RNG-REQ retry counter; clear T3 timer]
+    ResetRNGREQ --> AbortRanging
+    
+    SuccessRanging -- Yes --> ClearSuspend[Clear transmission suspend]
+    SuccessRanging -- No --> SuspendSuspend[Suspend transmission of everything except RNG-REQs]
+    
+    ClearSuspend --> AdjustParams[Adjust local parameters per RNG-RSP]
+    SuspendSuspend --> AdjustParams
+    
+    AdjustParams --> Operational
+    Error --> Operational
+  
+```
+
+Flowchart for Periodic ranging - CM view. The process starts at 'Operational' and branches into 'Unicast maintenance opportunity', 'Timeout T3', 'Timeout T4', and 'RNG-RSP'. The 'Unicast maintenance opportunity' path leads to 'Start T4 timer', 'Send RNG-REQ', 'Increment RNG-REQ retry counter', and 'Start T3 timer'. The 'RNG-REQ' path leads to a decision 'RNG-REQ retries exceeded?'. If 'Yes', it leads to 'Error: re-initialize MAC'. If 'No', it loops back to 'Start T3 timer'. The 'Timeout T3' path leads to the 'RNG-REQ retries exceeded?' decision. The 'Timeout T4' path leads to 'Abort ranging from CMTS?'. The 'RNG-RSP' path leads to 'T3 timer started?'. If 'Yes', it leads to 'Reset RNG-REQ retry counter; clear T3 timer'. If 'No', it leads to 'Abort ranging from CMTS?'. From 'Abort ranging from CMTS?', if 'Yes', it leads to 'Error: re-initialize MAC'. If 'No', it leads to 'Success ranging from CMTS?'. If 'Yes', it leads to 'Clear transmission suspend' and then 'Adjust local parameters per RNG-RSP'. If 'No', it leads to 'Suspend transmission of everything except RNG-REQs' and then 'Adjust local parameters per RNG-RSP'. Both 'Adjust local parameters per RNG-RSP' and 'Error: re-initialize MAC' lead back to 'Operational'.
+
+**Figure 11-17 – Periodic ranging – CM view**
+
+### 11.3.2 Changing upstream channel descriptor message parameters
+
+Whenever the CMTS is to change any of the upstream burst characteristics specified in the upstream channel descriptor (UCD) message (see clause 8.3.3), it must provide for an orderly transition from the old values to the new values by all CMs. Whenever the CMTS is to change any of the upstream characteristics, it **MUST** announce the new values in an UCD message, and the configuration change count field in that UCD message **MUST** be incremented to indicate that a value has changed.
+
+After transmitting one or more UCD messages with the new value, the CMTS transmits a MAP message with a UCD change count matching the new configuration change count. The first interval in the MAP **MUST** be a data grant of at least 1 millisecond to the null service ID (zero). In the case of S-CDMA channels, that grant to the null service ID **MUST** be at least the longer of 1-ms or the duration of 2 S-CDMA frames to allow for the latency of the S-CDMA framing, and the start time of the MAP with the new UCD change count **MUST** correspond to the beginning of an S-CDMA frame. The CMTS **MUST** allow this time for cable modems to change their PMD sublayer parameters to match the new set. This time is independent of the lead time the CMTS needed to allow for in transmitting the MAP (see clause 9.1.5). The CMTS **MUST** transmit the new UCD message early enough that the CM receives the UCD message at least the UCD processing time (see Annex B) prior to the time the first MAP using the new UCD parameters arrives at the CM.
+
+With the following exceptions, the CM MUST be able to transmit normally on the first grant following the grant to the NULL SID. The exceptions are the case where the new UCD message has changed the S-CDMA enable parameter, or the S-CDMA US ratio numerator or denominator. In these cases, the CM MAY redo initial ranging to establish timing synchronization for the new mode of operation before it resumes normal transmissions. If the CM was already registered with the CMTS, and it redoes initial ranging for this reason, it MUST use its primary SID instead of the initialization SID for the initial ranging process and it MUST NOT re-register. Using the ranging required parameter in the new UCD message, the CMTS can force the CM to perform ranging prior to making any other transmissions using the parameters in the new UCD message. In certain cases, channel-wide parameter changes (in particular, modulation rate or centre frequency) may invalidate pre-equalization and synchronization parameters, and normal operation may not be possible without re-ranging. If the CMTS changes the modulation rate or centre frequency on an S-CDMA channel, it MUST force re-ranging using the ranging required parameter.
+
+In the case of an S-CDMA channel, the first UCD message with a new configuration count and any subsequent UCD messages that may be sent prior to the first MAP with the new UCD change count MUST have an updated timestamp snapshot corresponding to the start time of that first MAP with the new UCD change count. Also on an S-CDMA channel, the CMTS MUST maintain the continuity of the mini-slot and S-CDMA frame counters during the change in UCD parameters even if the size of a mini-slot is changed.
+
+The CMTS MUST NOT transmit MAPs with the old UCD change count after transmitting the new UCD message.
+
+The CM MUST use the parameters from the UCD message corresponding to the MAP's UCD change count for any transmissions it makes in response to that MAP. If the CM has, for any reason, not received the corresponding UCD message, it cannot transmit during the interval described by that MAP.
+
+It is possible for the change in upstream parameters to cause the upstream to change from a type 1 upstream (see clause 11.2.2) to a type 2 upstream or a type 3 upstream. If this happens, and the CM registered with a configuration file that enables 2.0 mode (see clause 11.2.8), then the CM MUST operate in 2.0 mode. If the upstream has changed to a type 2 upstream this means that any request the CM transmits in an opportunity in the MAP with the new configuration change count or any subsequent MAP MUST be calculated in terms of IUCs 9 and 10, rather than IUCs 5 and 6, and the CMTS MUST issue grants using IUCs 9 and 10. However, if the CM registered with a configuration file that disabled 2.0 mode, then the CM MUST continue to calculate requests in terms of IUCs 5 and 6, and the CMTS MUST issue grants using IUCs 5 and 6. If the CM registered with a configuration file that disables 2.0 mode, and the new parameters have changed the upstream to a type 3 upstream, then the CM MUST immediately re-initialize the MAC layer and attempt registration. It should be understood by the network operator that changing a type 1 upstream to a type 3 upstream will cause a significant disruption of service for any CMs with 2.0 mode disabled as well as any DOCS 1.x CMs that are using the channel. Also such CMs will only be able to resume operation if there is a type 1 or type 2 upstream available to them.
+
+### 11.3.3 Changing upstream channels
+
+At any time after registration, the CMTS may direct the CM to change its upstream channel. This may be done for traffic balancing, noise avoidance or any of a number of other reasons which are beyond the scope of this Recommendation. Figure 11-18 shows the procedure that MUST be followed by the CMTS. Figures 11-19 and 11-20 show the corresponding procedure at the CM.
+
+![Flowchart illustrating the CMTS view for changing upstream channels. The process starts with 'Decide to switch CM to new upstream channel', followed by 'UCC-REQ', 'Wait for UCC-RSP', a 'Timeout T5' and 'UCC-RSP' parallel path, a 'Retries exhausted?' decision, and ends with 'CM is unreachable' or 'Done'.](b912fdb51e54b026873e19ecfb1ea1fa_img.jpg)
+
+```
+
+graph TD
+    A[Decide to switch CM to new upstream channel] --> B[/UCC-REQ/]
+    B --> C[Wait for UCC-RSP]
+    C --> D{Timeout T5}
+    C --> E[/UCC-RSP/]
+    D --> F{Retries exhausted?}
+    E --> G[Done]
+    F -- No --> B
+    F -- Yes --> H[CM is unreachable]
+    style G text-align: right
+    style G font-size: small
+    style G content: J.122_F11-18
+  
+```
+
+Flowchart illustrating the CMTS view for changing upstream channels. The process starts with 'Decide to switch CM to new upstream channel', followed by 'UCC-REQ', 'Wait for UCC-RSP', a 'Timeout T5' and 'UCC-RSP' parallel path, a 'Retries exhausted?' decision, and ends with 'CM is unreachable' or 'Done'.
+
+**Figure 11-18 – Changing upstream channels: CMTS view**
+
+Note that if the CMTS retries the UCC-REQ, the CM may have already changed channels (if the UCC-RSP was lost in transit). Consequently, the CMTS MUST listen for the UCC-RSP on both the old and the new channels.
+
+![Flowchart for 'Changing upstream channels: CM view, part 1'. The process starts with 'CM operational', followed by 'UCC-REQ'. A decision 'Already using this channel?' leads to 'UCC-RSP (reject already-there)' if Yes, or 'UCC-RSP' if No. The 'No' path leads to 'Switch to new channel', then 'Valid UCD for target upstream stored?'. If No, it goes to 'Wait for valid UCD for target upstream channel (or expiry of T1)'. A loop exists from this wait state back to the 'Valid UCD for target upstream stored?' decision. A callout '1' is next to the 'Wait' block. From 'Valid UCD for target upstream stored?', a 'Yes' path leads to 'Perform broadcast initial ranging'. From 'Wait for valid UCD...', a 'Yes' path also leads to 'Perform broadcast initial ranging'. From 'Perform broadcast initial ranging', the path goes to 'Ranging success?'. If No, it leads to 'CM UCC failed'. If Yes, it leads to 'CM operational' with a callout '2'.](e67a3090226f395f8e71864c84bdfa35_img.jpg)
+
+```
+
+graph TD
+    Start([CM operational]) --> UCC_REQ[/UCC-REQ/]
+    UCC_REQ --> AlreadyUsing{Already using this channel?}
+    AlreadyUsing -- Yes --> UCC_RSP_Reject[/UCC-RSP (reject already-there)/]
+    UCC_RSP_Reject --> Start
+    AlreadyUsing -- No --> UCC_RSP[/UCC-RSP/]
+    UCC_RSP --> Switch[Switch to new channel]
+    Switch --> ValidUCDStored{Valid UCD for target upstream stored?}
+    ValidUCDStored -- No --> Wait[Wait for valid UCD for target upstream channel (or expiry of T1)]
+    Wait --> ValidUCDStored
+    ValidUCDStored -- Yes --> PerformRanging[Perform broadcast initial ranging]
+    Wait -- Yes --> PerformRanging
+    PerformRanging --> RangingSuccess{Ranging success?}
+    RangingSuccess -- No --> CMUCCFailed1([CM UCC failed])
+    RangingSuccess -- Yes --> CMOperational2([CM operational])
+  
+```
+
+①
+
+1. If DOCSIS 2.0 is enabled, a valid UCD describes either a type 1, 2 or 3 channel.
+2. If DOCSIS 2.0 is NOT enabled, a valid UCD describes a type 1 or type 2 channel.
+
+②
+
+The operational CM MUST base its requests on IUCs 9 and 10 if available and if DOCSIS 2.0 is enabled.
+
+J.122\_F11-19
+
+Flowchart for 'Changing upstream channels: CM view, part 1'. The process starts with 'CM operational', followed by 'UCC-REQ'. A decision 'Already using this channel?' leads to 'UCC-RSP (reject already-there)' if Yes, or 'UCC-RSP' if No. The 'No' path leads to 'Switch to new channel', then 'Valid UCD for target upstream stored?'. If No, it goes to 'Wait for valid UCD for target upstream channel (or expiry of T1)'. A loop exists from this wait state back to the 'Valid UCD for target upstream stored?' decision. A callout '1' is next to the 'Wait' block. From 'Valid UCD for target upstream stored?', a 'Yes' path leads to 'Perform broadcast initial ranging'. From 'Wait for valid UCD...', a 'Yes' path also leads to 'Perform broadcast initial ranging'. From 'Perform broadcast initial ranging', the path goes to 'Ranging success?'. If No, it leads to 'CM UCC failed'. If Yes, it leads to 'CM operational' with a callout '2'.
+
+**Figure 11-19 – Changing upstream channels: CM view, part 1**
+
+![Flowchart illustrating the CM view for changing upstream channels, Part 2. The sequence starts with 'CM UCC Failed' (oval), followed by 'ERROR: UCC failed <reason>' (parallelogram), 'Return to old upstream' (rectangle), 'Reset the MAC' (rectangle), and finally 'Obtain Upstream Parameters' (oval). A note to the right of the final step states: 'The state "Obtain Upstream Parameters" links to the state machine in Figure 11-1.'](70fd9003b407d059f32275b212482817_img.jpg)
+
+```
+
+graph TD
+    A([CM UCC Failed]) --> B[/ERROR:  
+UCC failed  
+<reason>/]
+    B --> C[Return to old  
+upstream]
+    C --> D[Reset the MAC]
+    D --> E([Obtain Upstream  
+Parameters])
+  
+```
+
+The state "Obtain Upstream Parameters" links to the state machine in Figure 11-1.
+
+Flowchart illustrating the CM view for changing upstream channels, Part 2. The sequence starts with 'CM UCC Failed' (oval), followed by 'ERROR: UCC failed ' (parallelogram), 'Return to old upstream' (rectangle), 'Reset the MAC' (rectangle), and finally 'Obtain Upstream Parameters' (oval). A note to the right of the final step states: 'The state "Obtain Upstream Parameters" links to the state machine in Figure 11-1.'
+
+J.122\_F11-20
+
+**Figure 11-20 – Changing upstream channels: CM view, Part 2**
+
+Upon synchronizing with the new upstream channel, the CM MUST perform broadcast initial ranging on the new upstream channel.
+
+If the CM has previously established ranging on the new channel, and if that ranging on that channel is still current (T4 has not elapsed since the last successful ranging), then the CM MAY use cached ranging information and omit ranging.
+
+The CM SHOULD cache UCD information from multiple upstream channels to eliminate waiting for a UCD corresponding to the new upstream channel.
+
+The CM MUST NOT perform re-registration, since its provisioning and MAC domain remain valid on the new channel.
+
+If a DOCS 2.0-enabled CM is moved from a type 1 channel to a type 2 channel via a UCC, the CM MUST operate in 2.0 mode on the destination channel, basing its requests on IUCs 9 and 10 instead of IUCs 5 and 6. If a CM in which DOCS 2.0 is disabled in registration is moved from a type 1 channel to a type 2 channel via a UCC, the CM MUST continue to base its requests on the destination channel on IUCs 5 and 6.
+
+#### 11.4 Dynamic service
+
+Service flows may be created, changed or deleted. This is accomplished through a series of MAC management messages referred to as dynamic service addition (DSA), dynamic service change (DSC) and dynamic service deletion (DSD). The DSA messages create a new service flow. The DSC messages change an existing service flow. The DSD messages delete a single existing upstream and/or a single existing downstream service flow. This is illustrated in Figure 11-21.
+
+![Figure 11-21 – Dynamic service flow overview. A state transition diagram showing two states: 'Null' and 'Operational'. Transitions are labeled DSD, DSA, and DSC. The diagram is labeled J.122_F11-21.](c07bedd918cbe46227a83594c2745b25_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> Null
+    Null --> Operational : DSA
+    Operational --> Null : DSD
+    Operational --> Operational : DSC
+  
+```
+
+The diagram illustrates the dynamic service flow overview. It consists of two states: 'Null' and 'Operational'. The 'Null' state is represented by a single circle, and the 'Operational' state is represented by a double circle. Transitions between states are indicated by arrows: a straight arrow from 'Null' to 'Operational' labeled 'DSA', a curved arrow from 'Operational' back to 'Null' labeled 'DSD', and a self-loop arrow on the 'Operational' state labeled 'DSC'. The diagram is labeled 'J.122\_F11-21' at the bottom right.
+
+Figure 11-21 – Dynamic service flow overview. A state transition diagram showing two states: 'Null' and 'Operational'. Transitions are labeled DSD, DSA, and DSC. The diagram is labeled J.122\_F11-21.
+
+**Figure 11-21 – Dynamic service flow overview**
+
+The null state implies that no service flow exists that matches the SFID and/or TransactionID in a message. Once the service flow exists, it is operational and has an assigned SFID. In steady state operation, a service flow resides in a nominal state. When dynamic service messaging is occurring, the service flow may transition through other states, but remains operational. Since multiple service flows may exist, there may be multiple state machines active, one for every service flow. Dynamic service messages only affect those state machines that match both the SFID and/or transaction ID or SFID only. A transaction ID which is reused for other SFID(s) indicates that the other side terminated the previous transaction. If a dynamic service request message is received that refers to the same transaction ID as one that has already been processed, but service flow(s) other than those locked in this transaction, the device MAY trigger a DSx ended input to the state machine(s) of SF(s) involved in the previous transaction. If privacy is enabled, both the CM and CMTS MUST verify the HMAC digest on all dynamic service messages before processing them, and discard any messages that fail.
+
+Service flows created at registration time effectively enter the SF\_operational state without a DSA transaction.
+
+TransactionIDs are unique per transaction and are selected by the initiating device (CM or CMTS). To help prevent ambiguity and provide simple checking, the TransactionID number space is split between the CM and CMTS. The CM MUST select its TransactionIDs from the first half of the number space (0x0000 to 0x7FFF). The CMTS MUST select its TransactionIDs from the second half of the number space (0x8000 to 0xFFFF).
+
+Each dynamic service message sequence is a unique transaction with an associated unique transaction identifier. To help support transaction identifier uniqueness between two devices in different states, the transaction initiating device SHOULD change the transaction identifier for each new initiated transaction. It MUST wait at least T10 to reuse the transaction identifier. The DSA/DSC transactions consist of a request/response/acknowledge sequence. The DSD transactions consist of a request/response sequence. The response messages MUST contain a confirmation code of okay unless some exception condition was detected. The acknowledge messages MUST include the confirmation code in the response unless a new exception condition arises. A more detailed state diagram, including transition states, is shown below. The detailed actions for each transaction will be given in the following clauses.
+
+#### 11.4.1 Dynamic service flow state transitions
+
+The dynamic service flow state transition diagram is the top-level state diagram and controls the general service flow state. As needed, it creates transactions, each represented by a transaction state transition diagram, to provide the DSA, DSC and DSD signalling. Each transaction state transition diagram only communicates with the parent dynamic service flow state transition diagram. The top-level state transition diagram filters dynamic service messages and passes them to the
+
+appropriate transaction based on service flow identifier (SFID), service flow reference number and TransactionID.
+
+If a single dynamic service message affects a pair of service flows, a single transaction is initiated which communicates with both parent dynamic service flow state transition diagrams. In this case, both service flows MUST remain locked in the same state until they receive the DSx succeeded or DSx failed input from the DSx transaction state transition diagram. During that "lock interval", if a message is received that refers to only one of the two service flows, it MUST be treated as if it refers to both service flows, so that both service flows stay in the same state. If a DSD-REQ message is received during the lock interval that refers to only one of the two service flows, the device MUST handle the event normally, by sending the SF Delete-Remote to the ongoing DSx transaction and by initiating a DSD-Remote transaction, and in addition, it MUST initiate a DSD-Local transaction to delete the second service flow of the locked pair.
+
+If a DSC request is received that refers to two service flows locked in different transactions, and they are in different states, the device MUST reject the request without affecting the ongoing transactions.
+
+There are six different types of transactions: locally initiated or remotely initiated for each of the DSA, DSC and DSD messages. Most transactions have three basic states: pending, holding and deleting. The pending state is typically entered after creation and is where the transaction is waiting for a reply. The holding state is typically entered once the reply is received. The purpose of this state is to allow for retransmissions in case of a lost message, even though the local entity has perceived that the transaction has completed. The deleting state is only entered if the service flow is being deleted while a transaction is being processed.
+
+The flow diagrams provide a detailed representation of each of the states in the transaction state transition diagrams. All valid transitions are shown. Any inputs not shown should be handled as a severe error condition.
+
+With one exception, these state diagrams apply equally to the CMTS and CM. In the dynamic service flow changing-local state, there is a subtle difference in the CM and CMTS behaviours. This is called out in the state transition and detailed flow diagrams.
+
+NOTE – The 'Num Xacts' variable in the dynamic service flow state transition diagram is incremented every time the top-level state diagram creates a transaction and is decremented every time a transaction terminates. A dynamic service flow MUST NOT return to the null state until it is deleted and all transactions have terminated.
+
+The inputs for the state diagrams are identified below.
+
+Dynamic service flow state transition diagram inputs from unspecified local, higher-level entities:
+
+- Add;
+- Change;
+- Delete.
+
+Dynamic service flow state transition diagram inputs from DSx transaction state transition diagrams:
+
+- DSA Succeeded;
+- DSA Failed;
+- DSA ACK Lost;
+- DSA Erred;
+- DSA Ended;
+- DSC Succeeded;
+- DSC Failed;
+
+- DSC ACK Lost;
+- DSC Erred;
+- DSC Ended;
+- DSD Succeeded;
+- DSD Erred;
+- DSD Ended.
+
+DSx transaction state transition diagram inputs from the dynamic service flow state transition diagram:
+
+- SF Add;
+- SF Change;
+- SF Delete;
+- SF Abort Add;
+- SF Change-Remote;
+- SF Delete-Local;
+- SF Delete-Remote;
+- SF DSA-ACK Lost;
+- SF-DSC-REQ Lost;
+- SF-DSC-ACK Lost;
+- SF DSD-REQ Lost;
+- SF Changed;
+- SF Deleted.
+
+The creation of DSx transactions by the dynamic service flow state transition diagram is indicated by the notation:
+
+DSx-[Local|Remote] ( initial\_input )
+
+where initial\_input may be SF Add, DSA-REQ, SF Change, DSC-REQ, SF Delete or DSD-REQ depending on the transaction type and initiator.
+
+![Dynamic service flow state transition diagram showing states: Null, Adding Local, Adding Remote, Add Failed, Nominal, Changing Local, Changing Remote, Deleting, Deleted. Transitions are triggered by events like Add/DSA-Local, DSA-REQ, DSC-REQ, and Delete, with outcomes like Succeeded, Failed, or Erred.](ba596ecf0bd3f3520b7b5c2c857a9ec3_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> Null
+    Null --> Adding Local: Add/DSA-Local(SF Add)
+    Null --> Add Failed: DSA Ended/
+    Null --> Adding Remote: DSA-REQ/DSA-Remote(DSA-REQ)
+    Adding Local --> Add Failed: (DSA Failed/ (Delete/SFAbort Add) (DSA Ended/))
+    Adding Local --> Nominal: DSA Succeeded/
+    Adding Remote --> Add Failed: DSA Failed/
+    Adding Remote --> Nominal: DSA Succeeded/
+    Adding Remote --> Adding Remote: DSC-REQ/SF DSA-ACK Lost
+    Adding Remote --> Deleting: (DSA Erred/ DSD-Local(SF Delete)) (Delete/SF Delete-Local, DSD-Local(SF Delete))
+    Add Failed --> Null: DSA Ended/
+    Nominal --> Changing Local: (DSC-REQ/[CMTS Only]) (DSA ACK Lost/ SF DSC-REQ Lost) (DSC ACK Lost/ SF DSC-REQ Lost)
+    Nominal --> Changing Remote: DSC-REQ/ SF Change-Remote, DSC-Remote(DSC-REQ)
+    Changing Local --> Nominal: Change/ DSC-Local(SF Change)
+    Changing Local --> Deleting: (DSC Erred/SF Delete-Local, DSD-Local(SF Delete)) (Delete/SF Delete-Local, DSD-Local(SF Delete))
+    Changing Remote --> Nominal: (DSC Succeeded/ SF Changed) (DSC Failed/ SF Changed)
+    Changing Remote --> Deleting: (DSC Erred/ DSD-Local(SF Delete)) (Delete/SF Delete-Local, DSD-Local(SF Delete))
+    Changing Remote --> Changing Remote: New DSC-REQ/ SF DSC-ACK Lost
+    Changing Local --> Changing Remote: DSC-REQ/SF Change-Remote, DSC-Remote(DSC-REQ) [CM Only]
+    Deleting --> Deleted: (DSD Succeeded/SF Deleted) (DSD Erred/SF Deleted)
+    Deleted --> Null: DSD Ended && Num Xacts == 0/
+    Deleted --> Deleting: DSD Succeeded/SF Deleted
+  
+```
+
+Dynamic service flow state transition diagram showing states: Null, Adding Local, Adding Remote, Add Failed, Nominal, Changing Local, Changing Remote, Deleting, Deleted. Transitions are triggered by events like Add/DSA-Local, DSA-REQ, DSC-REQ, and Delete, with outcomes like Succeeded, Failed, or Erred.
+
+J.122\_F11-22
+
+Figure 11-22 – Dynamic service flow state transition diagram
+
+![State transition diagram for DSA - Locally-initiated transaction. States: Begin, DSA-RSP Pending, Retries Exhausted, Holding Down, Deleting Service Flow, End. Transitions include SF Add/DSA-REQ, Time-out T7, DSA-RSP/DSA-Succeeded, DSA-RSP/DSA-Failed, SF Abort Add/, DSA-RSP/DSA-ACK, DSA-ACK Lost, SF Delete Local/, Time-out T10, SF Changed, SF Change-Remote, SF Deleted, SF Delete-Remote.](89f64895932ad0d03d1e24c155c67628_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> DSA-RSP_Pending : SF Add/DSA-REQ
+    DSA-RSP_Pending --> DSA-RSP_Pending : Time-out T7 && Retries Available/DSA-REQ
+    DSA-RSP_Pending --> Retries_Exhausted : Time-out T7 && Retries Exhausted/
+    DSA-RSP_Pending --> Holding_Down : (DSA-RSP/DSA Succeeded, DSA-ACK)  
+(DSA-RSP/DSA Failed, DSA-ACK)  
+(SF Abort Add/)  
+
+    DSA-RSP_Pending --> Deleting_Service_Flow : DSA-RSP/DSA-ACK, DSA-ACK Lost
+    Retries_Exhausted --> Holding_Down : (DSA-RSP/DSA Succeeded, DSA-ACK)  
+(DSA-RSP/DSA Failed, DSA-ACK)  
+(SF Abort Add/)  
+
+    Retries_Exhausted --> End : Time-out T10/  
+DSA Erred, DSA Ended
+    Holding_Down --> Holding_Down : DSA-RSP/DSA-ACK, DSA-ACK Lost
+    Holding_Down --> Deleting_Service_Flow : SF Delete Local/
+    Holding_Down --> End : (Time-out T10/DSA Ended)  
+(SF Changed/DSA Ended)  
+(SF Change-Remote/DSA Ended)  
+
+    Deleting_Service_Flow --> Deleting_Service_Flow : DSA-RSP/DSA-ACK Lost
+    Deleting_Service_Flow --> End : (Time-out T10/DSA Ended)  
+(SF Deleted/DSA Ended)  
+
+    SF Delete-Remote/DSA Ended --> End
+  
+```
+
+J.122\_F11-23
+
+State transition diagram for DSA - Locally-initiated transaction. States: Begin, DSA-RSP Pending, Retries Exhausted, Holding Down, Deleting Service Flow, End. Transitions include SF Add/DSA-REQ, Time-out T7, DSA-RSP/DSA-Succeeded, DSA-RSP/DSA-Failed, SF Abort Add/, DSA-RSP/DSA-ACK, DSA-ACK Lost, SF Delete Local/, Time-out T10, SF Changed, SF Change-Remote, SF Deleted, SF Delete-Remote.
+
+**Figure 11-23 – DSA – Locally-initiated transaction state transition diagram**
+
+![State transition diagram for DSA - Remotely-initiated transaction. States: Begin, DSC-ACK Pending, Holding Down, Deleting Service Flow, End. Transitions include DSA-REQ/DSA-RSP, Time-out T8, SF Delete-Local, DSA-ACK, and various error/ended conditions.](d841e9dc5c67c17299341829b95da4ad_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> DSC-ACK Pending: (DSA-REQ/DSA-RSP) (DSA-REQ/DSA Failed, DSA-RSP)
+    DSC-ACK Pending --> DSC-ACK Pending: (Time-out T8 && Retries Available/DSA-RSP) (DSA-REQ && Retries Available/DSA-RSP) (DSA-REQ && Retries Exhausted/) (SF DSA-ACK Lost && Retries Available/DSA-RSP) (SF DSA-ACK Lost && Retries Exhausted/)
+    DSC-ACK Pending --> Holding Down: (DSA-ACK/DSA Succeeded) (DSA-ACK/DSA Failed)
+    DSC-ACK Pending --> Deleting Service Flow: SF Delete-Local/
+    Holding Down --> DSC-ACK Pending: (DSA-ACK/) (SF Delete-Local/) (SF Change-Remote/)
+    Holding Down --> End: (Time-out T8/DSA Ended) (SF Changed/DSA Ended) (SF Deleted/DSA Ended) (SF Delete-Remote/DSA Ended)
+    Holding Down --> DSC-ACK Pending: (Time-out T8 && Retries Exhausted/DSA Erred, DSA Ended) (SF Delete-Remote / DSA Ended)
+    Deleting Service Flow --> DSC-ACK Pending: (DSA-REQ/) (DSA-ACK/)
+    Deleting Service Flow --> End: (Time-out T10/DSA Ended) (SF Deleted/DSA Ended) (SF Delete-Remote/DSA Ended)
+  
+```
+
+State transition diagram for DSA - Remotely-initiated transaction. States: Begin, DSC-ACK Pending, Holding Down, Deleting Service Flow, End. Transitions include DSA-REQ/DSA-RSP, Time-out T8, SF Delete-Local, DSA-ACK, and various error/ended conditions.
+
+J.122\_F11-24
+
+**Figure 11-24 – DSA – Remotely-initiated transaction state transition diagram**
+
+![State transition diagram for DSC - Locally-initiated transaction. States: Begin, DSC-RSP Pending, Retries Exhausted, Holding Down, Deleting Service Flow, End. Transitions include SF Change/DSC-REQ, Time-out T7, DSC-RSP/DSC Succeeded, DSC-RSP/DSC Failed, SF Delete-Local, DSC-RSP/DSC ACK Lost, Time-out T10, SF Delete-Remote.](b579792544f9149f386017e067fdd21e_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> DSC-RSP Pending : SF Change/DSC-REQ
+    DSC-RSP Pending --> DSC-RSP Pending : (Time-out T7 && Retries Available/DSC-REQ)
+    DSC-RSP Pending --> DSC-RSP Pending : (SF DSC-REQ Lost && Retries Available/DSC-REQ)
+    DSC-RSP Pending --> DSC-RSP Pending : (SF DSC-REQ Lost && Retries Exhausted/)
+    DSC-RSP Pending --> Retries Exhausted : Time-out T7 && Retries Exhausted/
+    DSC-RSP Pending --> Holding Down : (DSC-RSP/DSC Succeeded, DSC-ACK)
+    DSC-RSP Pending --> Holding Down : (DSC-RSP/DSC Failed, DSC-ACK)
+    DSC-RSP Pending --> Deleting Service Flow : SF Change-Remote/DSC Ended [CM Only]
+    Retries Exhausted --> Holding Down : (DSC-RSP/DSC Succeeded, DSC-ACK)
+    Retries Exhausted --> Holding Down : (DSC-RSP/DSC Failed, DSC-ACK)
+    Retries Exhausted --> End : Time-out T10/ DSC Erred, DSC Ended
+    Holding Down --> Holding Down : DSC-RSP/ DSC-ACK, DSC-ACK Lost
+    Holding Down --> End : (Time-out T10/DSC Ended)
+    Holding Down --> End : (SF Changed/DSC Ended)
+    Holding Down --> End : (SF Change-Remote/DSC Ended)
+    Deleting Service Flow --> Deleting Service Flow : DSC-RSP/ DSC-ACK Lost
+    Deleting Service Flow --> End : (Time-out T10/DSC Ended)
+    Deleting Service Flow --> End : (SF Deleted/DSC Ended)
+    Deleting Service Flow --> End : SF Delete-Remote/DSC Ended
+  
+```
+
+J.122\_F11-25
+
+State transition diagram for DSC - Locally-initiated transaction. States: Begin, DSC-RSP Pending, Retries Exhausted, Holding Down, Deleting Service Flow, End. Transitions include SF Change/DSC-REQ, Time-out T7, DSC-RSP/DSC Succeeded, DSC-RSP/DSC Failed, SF Delete-Local, DSC-RSP/DSC ACK Lost, Time-out T10, SF Delete-Remote.
+
+**Figure 11-25 – DSC – Locally-initiated transaction state transition diagram**
+
+![State transition diagram for DSC - Remotely-initiated transaction. States: Begin, DSC-ACK Pending, Holding Down, Deleting Service Flow, End. Transitions include DSC-REQ/DSC-RSP, (Time-out T8 && Retries Available/DSC-RSP), (DSC-REQ && Retries Available/DSC-RSP), (DSC-REQ && Retries Exhausted/), (SF DSC-ACK Lost && Retries Available/DSC-RSP), (SF DSC-ACK Lost && Retries Exhausted/), (DSC-ACK/DSC Succeeded), (DSC-ACK/DSC Failed), (Time-out T8 && Retries Exhausted/DSC Erred, DSC Ended), (SF Delete-Remote/DSC Ended), (DSC-ACK/), (SF Delete-Local/), (SF Change-Remote/), (Time-out T8/DSC Ended), (SF Changed/DSC Ended), (SF Deleted/DSC Ended), (SF Delete-Remote/DSC Ended), (Time-out T10/DSC Ended), (SF Deleted/DSC Ended), (SF Delete-Remote/DSC Ended), SF Delete-Local/.](29a5f4072e91dc4857fce0ace805e0d4_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> DSC-ACK Pending : DSC-REQ/DSC-RSP
+    DSC-ACK Pending --> DSC-ACK Pending : (Time-out T8 && Retries Available/DSC-RSP)
+    DSC-ACK Pending --> DSC-ACK Pending : (DSC-REQ && Retries Available/DSC-RSP)
+    DSC-ACK Pending --> DSC-ACK Pending : (DSC-REQ && Retries Exhausted/)
+    DSC-ACK Pending --> DSC-ACK Pending : (SF DSC-ACK Lost && Retries Available/DSC-RSP)
+    DSC-ACK Pending --> DSC-ACK Pending : (SF DSC-ACK Lost && Retries Exhausted/)
+    DSC-ACK Pending --> Holding Down : (DSC-ACK/DSC Succeeded)
+    DSC-ACK Pending --> Holding Down : (DSC-ACK/DSC Failed)
+    DSC-ACK Pending --> Deleting Service Flow : SF Delete-Local/
+    Holding Down --> DSC-ACK Pending : (DSC-ACK/), (SF Delete-Local/), (SF Change-Remote/)
+    Holding Down --> [*] : (Time-out T8/DSC Ended), (SF Changed/DSC Ended), (SF Deleted/DSC Ended), (SF Delete-Remote/DSC Ended)
+    Holding Down --> DSC-ACK Pending : (Time-out T8 && Retries Exhausted/DSC Erred, DSC Ended), (SF Delete-Remote/DSC Ended)
+    Deleting Service Flow --> DSC-ACK Pending : (DSC-REQ/), (DSC-ACK/)
+    Deleting Service Flow --> [*] : (Time-out T10/DSC Ended), (SF Deleted/DSC Ended), (SF Delete-Remote/DSC Ended)
+  
+```
+
+State transition diagram for DSC - Remotely-initiated transaction. States: Begin, DSC-ACK Pending, Holding Down, Deleting Service Flow, End. Transitions include DSC-REQ/DSC-RSP, (Time-out T8 && Retries Available/DSC-RSP), (DSC-REQ && Retries Available/DSC-RSP), (DSC-REQ && Retries Exhausted/), (SF DSC-ACK Lost && Retries Available/DSC-RSP), (SF DSC-ACK Lost && Retries Exhausted/), (DSC-ACK/DSC Succeeded), (DSC-ACK/DSC Failed), (Time-out T8 && Retries Exhausted/DSC Erred, DSC Ended), (SF Delete-Remote/DSC Ended), (DSC-ACK/), (SF Delete-Local/), (SF Change-Remote/), (Time-out T8/DSC Ended), (SF Changed/DSC Ended), (SF Deleted/DSC Ended), (SF Delete-Remote/DSC Ended), (Time-out T10/DSC Ended), (SF Deleted/DSC Ended), (SF Delete-Remote/DSC Ended), SF Delete-Local/.
+
+J.122\_F11-26
+
+Figure 11-26 – DSC – Remotely-initiated transaction state transition diagram
+
+![State transition diagram for DSD - Locally-initiated transaction. States: Begin, DSD-RSP Pending, Holding Down, End. Transitions include SF Delete/DSD-REQ, (Time-out T7 && Retries Available/DSD-REQ), (SF DSD-REQ Lost && Retries Available/DSD-REQ), (SF DSD-REQ Lost && Retries Exhausted/), (DSD-RSP/DSD Succeeded) (SF Delete-Remote/), (DSD-RSP/DSD Succeeded) (SF Deleted/), Time-out T7 && Retries Exhausted/DSD Erred, DSD Ended, and Time-out T7/DSD Ended.](36a1eab8868d8db81c6b28fbd0d5730f_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> DSD-RSP_Pending : SF Delete/DSD-REQ
+    state "DSD-RSP Pending" as DSD-RSP_Pending
+    DSD-RSP_Pending --> DSD-RSP_Pending : (Time-out T7 && Retries Available/DSD-REQ)
+    DSD-RSP_Pending --> DSD-RSP_Pending : (SF DSD-REQ Lost && Retries Available/DSD-REQ)
+    DSD-RSP_Pending --> DSD-RSP_Pending : (SF DSD-REQ Lost && Retries Exhausted/)
+    DSD-RSP_Pending --> Holding_Down : (DSD-RSP/DSD Succeeded) (SF Delete-Remote/)
+    state "Holding Down" as Holding_Down
+    Holding_Down --> Holding_Down : (DSD-RSP/DSD Succeeded) (SF Deleted/)
+    Holding_Down --> [*] : Time-out T7 && Retries Exhausted/DSD Erred, DSD Ended
+    Holding_Down --> [*] : Time-out T7/DSD Ended
+  
+```
+
+J.122\_F11-27
+
+State transition diagram for DSD - Locally-initiated transaction. States: Begin, DSD-RSP Pending, Holding Down, End. Transitions include SF Delete/DSD-REQ, (Time-out T7 && Retries Available/DSD-REQ), (SF DSD-REQ Lost && Retries Available/DSD-REQ), (SF DSD-REQ Lost && Retries Exhausted/), (DSD-RSP/DSD Succeeded) (SF Delete-Remote/), (DSD-RSP/DSD Succeeded) (SF Deleted/), Time-out T7 && Retries Exhausted/DSD Erred, DSD Ended, and Time-out T7/DSD Ended.
+
+**Figure 11-27 – DSD – Locally-initiated transaction state transition diagram**
+
+![State transition diagram for Dynamic Deletion (DSD) - Remotely-initiated transaction. The diagram shows three states: Begin, Holding Down, and End. Transitions are labeled with messages and conditions.](fda52310e9cc2b82f0e0b5562d35c526_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> Begin
+    Begin --> Holding Down : DSD-REQ/DSD Succeeded, DSD-RSP
+    Holding Down --> Holding Down : DSD-REQ/DSD-RSP
+    Holding Down --> [*] : (Time-out T10/DSD Ended)  
+(SF Deleted/DSD Ended)
+  
+```
+
+J.122\_F11-28
+
+State transition diagram for Dynamic Deletion (DSD) - Remotely-initiated transaction. The diagram shows three states: Begin, Holding Down, and End. Transitions are labeled with messages and conditions.
+
+**Figure 11-28 – Dynamic deletion (DSD) – Remotely-initiated transaction state transition diagram**
+
+## 11.4.2 Dynamic service addition
+
+### 11.4.2.1 CM-initiated dynamic service addition
+
+A CM wishing to create an upstream and/or a downstream service flow sends a request to the CMTS using a dynamic service addition request message (DSA-REQ). The CMTS checks the CM's authorization for the requested service(s) and whether the QoS requirements can be supported, and generates an appropriate response using a dynamic service addition response message (DSA-RSP). The CM concludes the transaction with an acknowledgment message (DSA-ACK).
+
+In order to facilitate a common admission response, an upstream and a downstream service flow can be included in a single DSA-REQ. Both service flows are either accepted or rejected together.
+
+![](39148db4c9dfc296c5abced7b560a75b_img.jpg)
+
+| CM                                                                                                                              |                      | CMTS                                                                                                                                                                                                                                                                                                         |
+|---------------------------------------------------------------------------------------------------------------------------------|----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| New service flow(s) needed<br>Check if resources are available<br><b>Send DSA-REQ</b>                                           | ————— DSA-REQ —————→ | <b>Receive DSA-REQ</b><br>Check if CM authorized for service(s) <sup>a)</sup><br>Check service flow(s) QoS can be supported<br>Create SFID(s)<br>If upstream AdmittedQosParamSet is non-null, create SID<br>If upstream ActiveQosParamSet is non-null, enable reception of data on new upstream service flow |
+| <b>Receive DSA-RSP</b><br>If ActiveQosParamSet is non-null, enable transmission and/or reception of data on new service flow(s) | ←————— DSA-RSP ————— | <b>Send DSA-RSP</b>                                                                                                                                                                                                                                                                                          |
+| <b>Send DSA-ACK</b>                                                                                                             | ————— DSA-ACK —————→ | <b>Receive DSA-ACK</b><br>If downstream ActiveQosParamSet is non-null, enable transmission of data on new downstream service flow                                                                                                                                                                            |
+
+<sup>a)</sup> Authorization can happen prior to the DSA-REQ being received by the CMTS. The details of CMTS signalling to anticipate a DSA-REQ are beyond the scope of this Recommendation.
+
+**Figure 11-29 – Dynamic service addition initiated from CM**
+
+#### 11.4.2.2 CMTS-initiated dynamic service addition
+
+A CMTS wishing to establish an upstream and/or a downstream dynamic service flow(s) with a CM performs the following operations. The CMTS checks the authorization of the destination CM for the requested class of service and whether the QoS requirements can be supported. If the service can be supported, the CMTS generates new SFID(s) with the required class of service and informs the CM using a dynamic service addition request message (DSA-REQ). The CM checks that it can support the service and responds using a dynamic service addition response message (DSA-RSP). The transaction completes with the CMTS sending the acknowledge message (DSA-ACK).
+
+![](6ca811d98e22dc14235e6e77a7e919fb_img.jpg)
+
+| CM                                                                                                                                | CMTS                                                                                                                                                                                                                                                                                                     |
+|-----------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+|                                                                                                                                   | New service flow(s) required for CM<br>Check CM authorized for service(s)<br>Check service flow(s) QoS can be supported<br>Create SFID(s)<br>If upstream AdmittedQosParamSet is non-null, create SID<br>If upstream ActiveQosParamSet is non-null, enable reception of data on new upstream service flow |
+| <b>Receive DSA-REQ</b> ← DSA-REQ →                                                                                                | <b>Send DSA-REQ</b>                                                                                                                                                                                                                                                                                      |
+| Confirm CM can support service flow(s)<br>Add downstream SFID (if present)<br>Enable reception on any new downstream service flow |                                                                                                                                                                                                                                                                                                          |
+| <b>Send DSA-RSP</b> → DSA-RSP →                                                                                                   | <b>Receive DSA-RSP</b><br>Enable transmission and reception of data on new service flow(s)                                                                                                                                                                                                               |
+| <b>Receive DSA-ACK</b> ← DSA-ACK →                                                                                                | <b>Send DSA-ACK</b>                                                                                                                                                                                                                                                                                      |
+| Enable transmission on new upstream service flow                                                                                  |                                                                                                                                                                                                                                                                                                          |
+
+**Figure 11-30 – Dynamic service addition initiated from CMTS**
+
+### 11.4.2.3 Dynamic service addition state transition diagrams
+
+![Flowchart of DSA - Locally-initiated transaction begin state flow diagram](ac1b4040daa037941f51deeedbcd585a_img.jpg)
+
+```
+graph TD; A([DSA-Local begin]) --> B[/SF Add/]; B --> C[/DSA-REQ/]; C --> D[Start T7 timer]; D --> E[Save transmitted DSA-REQ]; E --> F[Set DSA -REQ retries available to 'DSx Request Retries']; F --> G([DSA-Local DSA-RSP pending]);
+```
+
+The flowchart illustrates the state transition process for a locally-initiated DSA transaction. It begins with a start node 'DSA-Local begin', followed by a process 'SF Add', then a message 'DSA-REQ', a process 'Start T7 timer', a process 'Save transmitted DSA-REQ', a process 'Set DSA -REQ retries available to 'DSx Request Retries'', and finally an end node 'DSA-Local DSA-RSP pending'. The diagram is labeled J.122\_F11-31.
+
+Flowchart of DSA - Locally-initiated transaction begin state flow diagram
+
+Figure 11-31 – DSA – Locally-initiated transaction begin state flow diagram
+
+![Flowchart for DSA-Locally-initiated transaction DSA-RSP pending state. The process starts at 'DSA-Local DSA-RSP Pending' and branches into four paths: Timeout T7, SF Delete-Remote, SF Abort Add, and DSA-RSP. Each path leads to specific processing steps such as stopping timers, saving requests or ACKs, and eventually reaching states like 'DSA-Local End' or 'DSA-Local Holding Down'.](6f7f18cd6ddcabd5553b75ef3dc97d15_img.jpg)
+
+```
+
+graph TD
+    Start([DSA-Local DSA-RSP Pending]) --> T7[Timeout T7]
+    Start --> SFDR[SF Delete-Remote]
+    Start --> SFAB[SF Abort Add]
+    Start --> DSA_RSP[DSA-RSP]
+
+    T7 --> Retries{Retries Available?}
+    Retries -- Yes --> SavedReq[/Saved DSA-REQ/]
+    SavedReq --> StartT7[Start T7 Timer]
+    StartT7 --> DecRetries[Decrement DSA-REQ  
+Retries Available]
+    DecRetries --> PendingRSP([DSA-Local DSA-RSP Pending])
+
+    Retries -- No --> StartT10[Start T10 Timer]
+    StartT10 --> RetriesExhausted([DSA-Local Retries Exhausted])
+
+    SFDR --> StopT7_1[Stop T7 Timer]
+    StopT7_1 --> Ended[/DSA Ended/]
+    Ended --> End([DSA-Local End])
+
+    SFAB --> StopT7_2[Stop T7 Timer]
+    StopT7_2 --> SaveACK[Save DSA-ACK with Condition Code 'reject-add-aborted']
+
+    DSA_RSP --> StopT7_3[Stop T7 Timer]
+    StopT7_3 --> Okay{Okay?}
+    Okay -- No --> Failed[/DSA Failed/]
+    Failed --> SetReject[Set Condition Code to 'reject-xxx']
+
+    Okay -- Yes --> Enable[Enable service flow]
+    Enable --> Succeeded[/DSA Succeeded/]
+    Succeeded --> SetOkay[Set Condition Code to 'okay']
+
+    SetReject --> ACK[/DSA-ACK/]
+    SetOkay --> ACK
+    SaveACK --> ACK
+
+    ACK --> SaveTrans[Save transmitted DSA-ACK]
+    SaveTrans --> StartT10_2[Start T10 Timer]
+    StartT10_2 --> HoldingDown([DSA-Local Holding Down])
+  
+```
+
+Flowchart for DSA-Locally-initiated transaction DSA-RSP pending state. The process starts at 'DSA-Local DSA-RSP Pending' and branches into four paths: Timeout T7, SF Delete-Remote, SF Abort Add, and DSA-RSP. Each path leads to specific processing steps such as stopping timers, saving requests or ACKs, and eventually reaching states like 'DSA-Local End' or 'DSA-Local Holding Down'.
+
+J.122\_F11-32
+
+Figure 11-32 – DSA – Locally-initiated transaction DSA-RSP pending state flow diagram
+
+![State flow diagram for DSA - Locally-initiated transaction holding state. The diagram starts with 'DSA-Local holding down' and branches into four paths: 'SF Changed, SF Change-Remote, SF Delete-Remote' leading to 'Stop T10 timer' then 'DSA Ended' then 'DSA-Local End'; 'Timeout T10' leading to 'DSA Ended'; 'SF Delete -Local' leading to 'DSA-Local deleting service flow'; and 'DSA-RSP' leading to 'Saved DSA-ACK' then 'DSA ACK Lost' then 'DSA-Local holding down'.](df79d6dd5d005b721cf6bcab34d6e12d_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> DSA-Local_holding_down : DSA-Local holding down
+    DSA-Local_holding_down --> SF_Changed : SF Changed, SF Change-Remote, SF Delete-Remote
+    DSA-Local_holding_down --> Timeout_T10 : Timeout T10
+    DSA-Local_holding_down --> SF_Delete_Local : SF Delete -Local
+    DSA-Local_holding_down --> DSA_RSP : DSA-RSP
+
+    SF_Changed --> Stop_T10_timer : Stop T10 timer
+    Stop_T10_timer --> DSA_Ended : DSA Ended
+    Timeout_T10 --> DSA_Ended
+
+    DSA_Ended --> DSA_Local_End : DSA-Local End
+
+    SF_Delete_Local --> DSA_Local_deleting_service_flow : DSA-Local deleting service flow
+
+    DSA_RSP --> Saved_DSA_ACK : Saved DSA-ACK
+    Saved_DSA_ACK --> DSA_ACK_Lost : DSA ACK Lost
+    DSA_ACK_Lost --> DSA_Local_holding_down
+  
+```
+
+State flow diagram for DSA - Locally-initiated transaction holding state. The diagram starts with 'DSA-Local holding down' and branches into four paths: 'SF Changed, SF Change-Remote, SF Delete-Remote' leading to 'Stop T10 timer' then 'DSA Ended' then 'DSA-Local End'; 'Timeout T10' leading to 'DSA Ended'; 'SF Delete -Local' leading to 'DSA-Local deleting service flow'; and 'DSA-RSP' leading to 'Saved DSA-ACK' then 'DSA ACK Lost' then 'DSA-Local holding down'.
+
+J.122\_F11-33
+
+**Figure 11-33 – DSA – Locally-initiated transaction holding state flow diagram**
+
+![Flowchart for DSA - Locally-initiated transaction retries exhausted state flow diagram. The process starts at 'DSA-Local retries exhausted' and branches into four paths: Timeout T10, SF Delete-Remote, SF Abort Add, and DSA-RSP. The DSA-RSP path includes an 'Okay?' decision leading to either 'Enable service flow' (Yes) or 'DSA Failed' (No).](6043644d04a0b251ad3e2ba078ae5ce4_img.jpg)
+
+```
+
+graph TD
+    Start([DSA-Local retries exhausted]) --> T10[/Timeout T10/]
+    Start --> SFDR[/SF Delete-Remote/]
+    Start --> SFAB[/SF Abort Add/]
+    Start --> DSA_RSP[/DSA-RSP/]
+
+    T10 --> DSA_Erred[/DSA Erred/]
+    SFDR --> StopT10[Stop T10 timer]
+    DSA_Erred --> DSA_Ended[/DSA Ended/]
+    StopT10 --> DSA_Ended
+    DSA_Ended --> DSA_Local_End([DSA-Local End])
+
+    SFAB --> SaveACK1[Save DSA-ACK with condition code 'reject-add-aborted']
+
+    DSA_RSP --> Okay{Okay?}
+    Okay -- No --> DSA_Failed[/DSA Failed/]
+    Okay -- Yes --> Enable[Enable service flow]
+
+    DSA_Failed --> SetCondition1[Set condition code to 'reject-xxx']
+    Enable --> DSA_Succeeded[/DSA Succeeded/]
+    DSA_Succeeded --> SetCondition2[Set condition code to 'okay']
+
+    SetCondition1 --> DSA_ACK[/DSA-ACK/]
+    SetCondition2 --> DSA_ACK
+
+    DSA_ACK --> SaveACK2[Save transmitted DSA-ACK]
+    SaveACK1 --> DSA_Local_HoldingDown([DSA-Local holding down])
+    SaveACK2 --> DSA_Local_HoldingDown
+
+    J122_F11-34((J.122_F11-34))
+  
+```
+
+Flowchart for DSA - Locally-initiated transaction retries exhausted state flow diagram. The process starts at 'DSA-Local retries exhausted' and branches into four paths: Timeout T10, SF Delete-Remote, SF Abort Add, and DSA-RSP. The DSA-RSP path includes an 'Okay?' decision leading to either 'Enable service flow' (Yes) or 'DSA Failed' (No).
+
+**Figure 11-34 – DSA – Locally-initiated transaction retries exhausted state flow diagram**
+
+![State flow diagram for DSA locally-initiated transaction deleting service flow. The process starts with 'DSA-Local deleting service flow', which branches into three paths: 'SF Deleted, SF Delete-Remote' leading to 'Stop T10 timer' then 'DSA Ended' then 'DSA-Local End'; 'Timeout T10' leading to 'DSA Ended'; and 'DSA-RSP' leading to 'DSA ACK Lost' then 'DSA-Local deleting service flow'.](ef8d84dccd07f6da2dd2abb10ba9d176_img.jpg)
+
+```
+
+graph TD
+    Start([DSA-Local deleting service flow]) --> SFDeleted[SF Deleted, SF Delete-Remote]
+    Start --> Timeout[Timeout T10]
+    Start --> DSA_RSP[DSA-RSP]
+    SFDeleted --> StopT10[Stop T10 timer]
+    Timeout --> DSA_Ended[DSA Ended]
+    StopT10 --> DSA_Ended
+    DSA_Ended --> DSA_Local_End([DSA-Local End])
+    DSA_RSP --> DSA_ACK_Lost[DSA ACK Lost]
+    DSA_ACK_Lost --> DSA_Local_Deleting([DSA-Local deleting service flow])
+    J122_F11-35[J.122_F11-35]
+  
+```
+
+State flow diagram for DSA locally-initiated transaction deleting service flow. The process starts with 'DSA-Local deleting service flow', which branches into three paths: 'SF Deleted, SF Delete-Remote' leading to 'Stop T10 timer' then 'DSA Ended' then 'DSA-Local End'; 'Timeout T10' leading to 'DSA Ended'; and 'DSA-RSP' leading to 'DSA ACK Lost' then 'DSA-Local deleting service flow'.
+
+**Figure 11-35 – DSA – Locally-initiated transaction deleting service flow state flow diagram**
+
+![Flowchart for DSA - Remotely-initiated transaction begin state flow diagram. The process starts with 'DSA-Remote begin', followed by 'DSA-REQ'. A decision 'Okay ?' follows. If 'No', it goes to 'DSA Failed' and then 'Set condition code to 'reject-xxx''. If 'Yes', it branches into '[ CM Only ] enable downstream service flow' and '[ CMTS Only ] enable upstream service flow'. Both lead to 'Set condition code to 'okay''. All three paths converge to 'DSA-RSP', 'Start T8 timer', 'Save transmitted DSA-RSP', 'Set DSA-RSP retries available to 'DSx Response Retries'', and finally 'DSA-Remote DSA-ACK pending'.](96d77cb2f738859fd462953fad369a1f_img.jpg)
+
+```
+
+graph TD
+    Start([DSA-Remote begin]) --> REQ[/DSA-REQ/]
+    REQ --> Okay{Okay ?}
+    Okay -- No --> Failed[/DSA Failed/]
+    Failed --> Reject[Set condition code to 'reject-xxx']
+    Okay -- Yes --> CMOnly[ "[ CM Only ]  
+enable  
+downstream  
+service flow" ]
+    Okay -- Yes --> CMTSOnly[ "[ CMTS Only ]  
+enable  
+upstream  
+service flow" ]
+    CMOnly --> OkayCode[Set condition code to 'okay']
+    CMTSOnly --> OkayCode
+    Reject --> RSP[/DSA-RSP/]
+    OkayCode --> RSP
+    RSP --> T8[Start T8 timer]
+    T8 --> Save[Save transmitted DSA-RSP]
+    Save --> Retries[Set DSA-RSP retries available to 'DSx Response Retries']
+    Retries --> ACK([DSA-Remote DSA-ACK pending])
+  
+```
+
+Flowchart for DSA - Remotely-initiated transaction begin state flow diagram. The process starts with 'DSA-Remote begin', followed by 'DSA-REQ'. A decision 'Okay ?' follows. If 'No', it goes to 'DSA Failed' and then 'Set condition code to 'reject-xxx''. If 'Yes', it branches into '[ CM Only ] enable downstream service flow' and '[ CMTS Only ] enable upstream service flow'. Both lead to 'Set condition code to 'okay''. All three paths converge to 'DSA-RSP', 'Start T8 timer', 'Save transmitted DSA-RSP', 'Set DSA-RSP retries available to 'DSx Response Retries'', and finally 'DSA-Remote DSA-ACK pending'.
+
+J.122\_F11-36
+
+**Figure 11-36 – DSA – Remotely-initiated transaction begin state flow diagram**
+
+![Flowchart for DSA - Remotely-initiated transaction DSA-ACK pending state. The process starts at 'DSA-Remote DSA-ACK pending' and branches into six main paths: DSA-REQ, SF DSA-ACK Lost, Timeout T8, SF Delete-Remote, SF Delete-Local, and DSA-ACK. Each path leads to specific actions like 'Stop T8 timer', 'Start T10 timer', 'Disable service flow', or 'DSA-Remote deleting service flow', eventually leading to states like 'DSA-Remote End', 'DSA-Remote holding down', or 'DSA-Remote DSA-ACK pending'.](2739376a35d7dce46136ce5412f7cf5a_img.jpg)
+
+```
+
+graph TD
+    Start([DSA-Remote DSA-ACK pending]) --> DSA-REQ[/DSA-REQ/]
+    Start --> SF_DSA_ACK_Lost[/SF DSA-ACK Lost/]
+    Start --> Timeout_T8[/Timeout T8/]
+    Start --> SF_Delete_Remote[/SF Delete-Remote/]
+    Start --> SF_Delete_Local[/SF Delete-Local/]
+    Start --> DSA_ACK[/DSA-ACK/]
+
+    DSA-REQ --> Retries_Avail_1{Retries available?}
+    SF_DSA_ACK_Lost --> Retries_Avail_1
+    Retries_Avail_1 -- No --> DSA-REQ
+    Retries_Avail_1 -- Yes --> Saved_DSA_RSP_1[/Saved DSA-RSP/]
+    Saved_DSA_RSP_1 --> Decrement_Retries[Decrement DSA-RSP retries available]
+    Decrement_Retries --> DSA_Remote_DSA_ACK_Pending_1([DSA-Remote DSA-ACK pending])
+
+    Timeout_T8 --> Retries_Avail_2{Retries available?}
+    Retries_Avail_2 -- No --> DSA_Err[/DSA Erred/]
+    Retries_Avail_2 -- Yes --> Saved_DSA_RSP_2[/Saved DSA-RSP/]
+    Saved_DSA_RSP_2 --> Start_T8_1[Start T8 timer]
+    Start_T8_1 --> Decrement_Retries
+
+    SF_Delete_Remote --> Stop_T8_1[Stop T8 timer]
+    Stop_T8_1 --> DSA_Err
+    DSA_Err --> DSA_End[/DSA Ended/]
+    DSA_End --> DSA_Remote_End([DSA-Remote End])
+
+    SF_Delete_Local --> Stop_T8_2[Stop T8 timer]
+    Stop_T8_2 --> Start_T10[Start T10 timer]
+    Start_T10 --> DSA_Remote_Deleting([DSA-Remote deleting service flow])
+
+    DSA_ACK --> Stop_T8_3[Stop T8 timer]
+    Stop_T8_3 --> Okay{Okay?}
+    Okay -- No --> Disable_Service_Flow[Disable service flow]
+    Okay -- Yes --> CM_Only_1[/[ CM Only ] enable upstream service flow/]
+    Okay -- Yes --> CMTS_Only_1[/[ CMTS Only ] enable downstream service flow/]
+    Disable_Service_Flow --> DSA_Failed[/DSA Failed/]
+    CM_Only_1 --> DSA_Succeeded[/DSA Succeeded/]
+    CMTS_Only_1 --> DSA_Succeeded
+    DSA_Failed --> Start_T8_2[Start T8 timer]
+    DSA_Succeeded --> Start_T8_2
+    Start_T8_2 --> DSA_Remote_Holding_Down([DSA-Remote holding down])
+  
+```
+
+Flowchart for DSA - Remotely-initiated transaction DSA-ACK pending state. The process starts at 'DSA-Remote DSA-ACK pending' and branches into six main paths: DSA-REQ, SF DSA-ACK Lost, Timeout T8, SF Delete-Remote, SF Delete-Local, and DSA-ACK. Each path leads to specific actions like 'Stop T8 timer', 'Start T10 timer', 'Disable service flow', or 'DSA-Remote deleting service flow', eventually leading to states like 'DSA-Remote End', 'DSA-Remote holding down', or 'DSA-Remote DSA-ACK pending'.
+
+J.122\_F11-37
+
+Figure 11-37 – DSA – Remotely-initiated transaction DSA-ACK pending state flow diagram
+
+![State flow diagram for DSA - Remotely-initiated transaction holding down. It starts with 'DSA-Remote holding down' and branches into four paths: 'SF Changed, SF Deleted, SF Delete-Remote' leading to 'Stop T8 timer' then 'DSA Ended' to 'DSA-Remote End'; 'Timeout T8' leading directly to 'DSA Ended'; 'SF Delete-Local, SF Change-Remote' leading to 'DSA-ACK' then 'DSA-Remote holding down'; and 'DSA-ACK' leading directly to 'DSA-Remote holding down'. Reference J.122_F11-38.](e9b0c54f494f276491a59ab381f2e5b2_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> DSA-Remote_holding_down : DSA-Remote holding down
+    DSA-Remote_holding_down --> SF_Changed_SF_Deleted_SF_Delete_Remote : SF Changed, SF Deleted, SF Delete-Remote
+    DSA-Remote_holding_down --> Timeout_T8 : Timeout T8
+    DSA-Remote_holding_down --> SF_Delete_Local_SF_Change_Remote : SF Delete-Local, SF Change-Remote
+    DSA-Remote_holding_down --> DSA_ACK : DSA-ACK
+    SF_Changed_SF_Deleted_SF_Delete_Remote --> Stop_T8_timer : Stop T8 timer
+    Stop_T8_timer --> DSA_Ended : DSA Ended
+    Timeout_T8 --> DSA_Ended
+    SF_Delete_Local_SF_Change_Remote --> DSA_ACK
+    DSA_ACK --> DSA-Remote_holding_down
+    DSA-Remote_holding_down --> DSA-Remote_holding_down
+    DSA_Ended --> DSA-Remote_End : DSA-Remote End
+  
+```
+
+J.122\_F11-38
+
+State flow diagram for DSA - Remotely-initiated transaction holding down. It starts with 'DSA-Remote holding down' and branches into four paths: 'SF Changed, SF Deleted, SF Delete-Remote' leading to 'Stop T8 timer' then 'DSA Ended' to 'DSA-Remote End'; 'Timeout T8' leading directly to 'DSA Ended'; 'SF Delete-Local, SF Change-Remote' leading to 'DSA-ACK' then 'DSA-Remote holding down'; and 'DSA-ACK' leading directly to 'DSA-Remote holding down'. Reference J.122\_F11-38.
+
+**Figure 11-38 – DSA – Remotely-initiated transaction holding down state flow diagram**
+
+![State flow diagram for DSA - Remotely-initiated transaction deleting service state. It starts with 'DSA-Remote deleting service flow' and branches into three paths: 'SF Deleted, SF Delete-Remote' leading to 'Stop T10 timer' then 'DSA Ended' to 'DSA-Remote End'; 'Timeout T10' leading directly to 'DSA Ended'; and 'DSA-REQ, DSA-ACK' leading to 'DSA-Remote deleting service flow'. Reference J.122_F11-39.](f738d8e7ef0493b52dacece33d4c5077_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> DSA-Remote_deleting_service_flow : DSA-Remote deleting service flow
+    DSA-Remote_deleting_service_flow --> SF_Deleted_SF_Delete_Remote : SF Deleted, SF Delete-Remote
+    DSA-Remote_deleting_service_flow --> Timeout_T10 : Timeout T10
+    DSA-Remote_deleting_service_flow --> DSA_REQ_DSA_ACK : DSA-REQ, DSA-ACK
+    SF_Deleted_SF_Delete_Remote --> Stop_T10_timer : Stop T10 timer
+    Stop_T10_timer --> DSA_Ended : DSA Ended
+    Timeout_T10 --> DSA_Ended
+    DSA_REQ_DSA_ACK --> DSA-Remote_deleting_service_flow
+    DSA_Ended --> DSA-Remote_End : DSA-Remote End
+  
+```
+
+J.122\_F11-39
+
+State flow diagram for DSA - Remotely-initiated transaction deleting service state. It starts with 'DSA-Remote deleting service flow' and branches into three paths: 'SF Deleted, SF Delete-Remote' leading to 'Stop T10 timer' then 'DSA Ended' to 'DSA-Remote End'; 'Timeout T10' leading directly to 'DSA Ended'; and 'DSA-REQ, DSA-ACK' leading to 'DSA-Remote deleting service flow'. Reference J.122\_F11-39.
+
+**Figure 11-39 – DSA – Remotely-initiated transaction deleting service state flow diagram**
+
+### 11.4.3 Dynamic service change
+
+The dynamic service change (DSC) set of messages is used to modify the flow parameters associated with a service flow. Specifically, DSC can:
+
+- modify the service flow specification;
+- add, delete or replace a flow classifier;
+- add, delete or set PHS elements.
+
+A single DSC message exchange can modify the parameters of one downstream service flow and/or one upstream service flow.
+
+To prevent packet loss, any required bandwidth change must be sequenced between the application generating the data and the bandwidth parameters of the service flow carrying the data. Because MAC messages can be lost, the timing of service flow parameter changes can vary, and it occurs at different times in the CM and CMTS. Applications should reduce their transmitted data bandwidth before initiating a DSC to reduce the service flow bandwidth, and should not increase their transmitted data bandwidth until after the completion of a DSC increasing the service flow bandwidth.
+
+The CMTS controls both upstream and downstream scheduling. Scheduling is based on data transmission requests and is subject to the limits contained in the current service flow parameters at the CMTS. The timing of service flow parameter changes, and any consequent scheduling changes, is independent of both direction and whether there is an increase or decrease in bandwidth. The CMTS always changes service flow parameters on receipt of a DSC-REQ (CM-initiated transaction) or DSC-RSP (CMTS-initiated transaction).
+
+The CMTS also controls the downstream transmit behaviour. The change in downstream transmit behaviour is always coincident with the change in downstream scheduling (i.e., CMTS controls both and changes both simultaneously).
+
+The CM controls the upstream transmit requests, subject to limits contained in the current service flow parameters at the CM. The timing of service flow parameter changes in the CM, and any consequent CM transmit request behaviour changes, is a function of which device initiated the transaction. For a CM-initiated DSC-REQ, the service flow parameters are changed on receipt of the DSC-RSP from the CMTS. For a CMTS-initiated DSC-REQ, the service flow parameters are changed on receipt of the DSC-REQ from the CMTS.
+
+Any service flow can be deactivated with a dynamic service change command by sending a DSC-REQ message, referencing the service flow identifier, and including a null ActiveQosParamSet. However, if a primary service flow of a CM is deactivated, that CM is de-registered and MUST re-register. Therefore, care should be taken before deactivating such service flows. If a service flow that was provisioned during registration is deactivated, the provisioning information for that service flow MUST be maintained until the service flow is reactivated.
+
+A CM MUST have only one DSC transaction outstanding per service flow. If it detects a second transaction initiated by the CMTS, the CM MUST abort the transaction it initiated and allow the CMTS-initiated transaction to complete.
+
+A CMTS MUST have only one DSC transaction outstanding per service flow. If it detects a second transaction initiated by the CM, the CMTS MUST abort the transaction the CM initiated and allow the CMTS-initiated transaction to complete.
+
+NOTE – Currently anticipated applications would probably control a service flow through either the CM or CMTS, and not both. Therefore, the case of a DSC being initiated simultaneously by the CM and CMTS is considered as an exception condition and treated as one.
+
+### 11.4.3.1 CM-initiated dynamic service change
+
+A CM that needs to change a service flow definition performs the following operations.
+
+The CM informs the CMTS using a dynamic service change request message (DSC-REQ). The CMTS MUST decide if the referenced service flow can support this modification. The CMTS MUST respond with a dynamic service change response (DSC-RSP) indicating acceptance or rejection. The CM reconfigures the service flow if appropriate, and then MUST respond with a dynamic service change acknowledge (DSC-ACK).
+
+![Sequence diagram for CM-initiated dynamic service change](bf9abec3605f1a8d00ae6524a9af02ed_img.jpg)
+
+This sequence diagram illustrates the interaction between a CMTS and a CM for a CM-initiated dynamic service change. The diagram is divided into two columns: CMTS on the left and CM on the right. The sequence of messages is as follows: 1. The CM sends a DSC-REQ message to the CMTS. The CM side of this message includes the text 'Service flow requires modifying'. 2. The CMTS receives the DSC-REQ and performs internal steps: 'Validate request' and 'Modify service flow'. 3. The CMTS then sends a DSC-RSP message back to the CM. 4. The CM receives the DSC-RSP and performs 'Modify service flow'. 5. Finally, the CM sends a DSC-ACK message to the CMTS, which the CMTS receives.
+
+| CMTS                | CM                              |
+|---------------------|---------------------------------|
+|                     | Service flow requires modifying |
+| Receive DSC-REQ     | Send DSC-REQ                    |
+| Validate request    |                                 |
+| Modify service flow |                                 |
+| Send DSC-RSP        | Receive DSC-RSP                 |
+|                     | Modify service flow             |
+| Receive DSC-ACK     | Send DSC-ACK                    |
+
+Sequence diagram for CM-initiated dynamic service change
+
+Figure 11-40 – CM-initiated DSC
+
+### 11.4.3.2 CMTS-initiated dynamic service change
+
+A CMTS that needs to change a service flow definition performs the following operations.
+
+The CMTS MUST decide if the referenced service flow can support this modification. If so, the CMTS informs the CM using a dynamic service change request message (DSC-REQ). The CM checks that it can support the service change, and MUST respond using a dynamic service change response (DSC-RSP) indicating acceptance or rejection. The CMTS reconfigures the service flow if appropriate, and then MUST respond with a dynamic service change acknowledgment (DSC-ACK).
+
+![Sequence diagram for CMTS-initiated dynamic service change](235dfd17045d5c48824e808c98dc82ec_img.jpg)
+
+This sequence diagram illustrates the interaction between a CMTS and a CM for a CMTS-initiated dynamic service change. The diagram is divided into two columns: CMTS on the left and CM on the right. The sequence of messages is as follows: 1. The CMTS performs an internal step 'Service flow requires modifying' and then sends a DSC-REQ message to the CM. 2. The CM receives the DSC-REQ and performs 'Modify service flow'. 3. The CM then sends a DSC-RSP message back to the CMTS. 4. The CMTS receives the DSC-RSP and performs 'Modify service flow'. 5. Finally, the CMTS sends a DSC-ACK message to the CM, which the CM receives.
+
+| CMTS                            | CM                  |
+|---------------------------------|---------------------|
+| Service flow requires modifying |                     |
+| Send DSC-REQ                    | Receive DSC-REQ     |
+|                                 | Modify service flow |
+| Receive DSC-RSP                 | Send DSC-RSP        |
+| Modify service flow             |                     |
+| Send DSC-ACK                    | Receive DSC-ACK     |
+
+Sequence diagram for CMTS-initiated dynamic service change
+
+Figure 11-41 – CMTS-initiated DSC
+
+### 11.4.3.3 Dynamic service change state transition diagrams
+
+![Flowchart of the DSC locally-initiated transaction begin state flow diagram.](d4f75478414255f10396bc4f38edeebb_img.jpg)
+
+```
+graph TD; A([DSC-Local Begin]) --> B[/SF Change/]; B --> C[Save service flow QoS state]; C --> D["[ CM Only ]  
+If decrease upstream bandwidth, modify transmission"]; D --> E[/DSC-REQ/]; E --> F[Start T7 Timer]; F --> G[Save transmitted DSC-REQ]; G --> H["Set DSC-REQ  
+Retries Available  
+to 'DSx Request  
+Retries'"]; H --> I([DSC-Local DSC-RSP Pending]);
+```
+
+The flowchart illustrates the sequence of operations for a locally-initiated DSC transaction. It begins with 'DSC-Local Begin', followed by 'SF Change', 'Save service flow QoS state', a conditional step '[ CM Only ] If decrease upstream bandwidth, modify transmission', 'DSC-REQ', 'Start T7 Timer', 'Save transmitted DSC-REQ', 'Set DSC-REQ Retries Available to 'DSx Request Retries'', and finally 'DSC-Local DSC-RSP Pending'.
+
+J.122\_F11-42
+
+Flowchart of the DSC locally-initiated transaction begin state flow diagram.
+
+Figure 11-42 – DSC – Locally-initiated transaction begin state flow diagram
+
+![Flowchart for DSC - Locally-initiated transaction DSC-RSP pending state. The process starts at 'DSC-Local DSC-RSP pending' and branches into six paths: SF DSC-REQ Lost, Timeout T7, SF Change-Remote [ CM only ], SF Delete-Remote, SF Delete-Local, and DSC-RSP. Each path leads to specific state transitions and timer management, eventually returning to 'DSC-Local DSC-RSP pending' or ending in 'DSC-Local End' or 'DSC-Local holding down'.](28583b06f211df822423d245dfad776f_img.jpg)
+
+```
+
+graph TD
+    Start([DSC-Local DSC-RSP pending]) --> SF_DSC_REQ_Lost[/SF DSC-REQ Lost/]
+    Start --> Timeout_T7[/Timeout T7/]
+    Start --> SF_Change_Remote[/SF Change-Remote [ CM only ]/]
+    Start --> SF_Delete_Remote[/SF Delete-Remote/]
+    Start --> SF_Delete_Local[/SF Delete-Local/]
+    Start --> DSC_RSP[/DSC-RSP/]
+
+    SF_DSC_REQ_Lost --> Retries_Avail_1{Retries available?}
+    Retries_Avail_1 -- No --> SF_DSC_REQ_Lost
+    Retries_Avail_1 -- Yes --> Saved_DSC_REQ_1[/Saved DSC-REQ/]
+    Saved_DSC_REQ_1 --> Decrement_DSC_REQ_Retries[Decrement DSC-REQ retries available]
+    Decrement_DSC_REQ_Retries --> Start_T7_1[Start T7 Timer]
+    Start_T7_1 --> Saved_DSC_REQ_2[/Saved DSC-REQ/]
+    Saved_DSC_REQ_2 --> Start_T7_2[Start T7 Timer]
+    Start_T7_2 --> Decrement_DSC_REQ_Retries
+    Start_T7_2 --> DSC_Local_End([DSC-Local End])
+
+    Timeout_T7 --> Retries_Avail_2{Retries available?}
+    Retries_Avail_2 -- No --> Start_T10_1[Start T10 timer]
+    Start_T10_1 --> DSC_Local_End
+    Retries_Avail_2 -- Yes --> Saved_DSC_REQ_3[/Saved DSC-REQ/]
+    Saved_DSC_REQ_3 --> Start_T7_3[Start T7 Timer]
+    Start_T7_3 --> Decrement_DSC_REQ_Retries
+    Start_T7_3 --> DSC_Local_End
+
+    SF_Change_Remote --> Stop_T7_1[Stop T7 timer]
+    Stop_T7_1 --> DSC_Ended[/DSC Ended/]
+    DSC_Ended --> DSC_Local_End
+
+    SF_Delete_Remote --> Stop_T7_2[Stop T7 timer]
+    Stop_T7_2 --> DSC_Ended
+    DSC_Ended --> DSC_Local_End
+
+    SF_Delete_Local --> Stop_T7_3[Stop T7 timer]
+    Stop_T7_3 --> Start_T10_2[Start T10 timer]
+    Start_T10_2 --> DSC_Local_End
+
+    DSC_RSP --> Stop_T7_4[Stop T7 timer]
+    Stop_T7_4 --> Okay{Okay?}
+    Okay -- No --> Restore_QoS[Restore service flow QoS state]
+    Okay -- Yes --> Modify_Params[Modify service flow parameters]
+    Restore_QoS --> DSC_Failed[/DSC Failed/]
+    DSC_Failed --> Set_Reject[Set condition code to 'reject-xxx']
+    Set_Reject --> Start_T10_3[Start T10 timer]
+    Modify_Params --> DSC_Succeeded[/DSC Succeeded/]
+    DSC_Succeeded --> Set_Okay[Set condition code to 'okay']
+    Set_Okay --> DSC_ACK[/DSC-ACK/]
+    DSC_ACK --> Start_T10_3
+    Start_T10_3 --> Save_ACK[Save transmitted DSC-ACK]
+    Save_ACK --> DSC_Local_Holding_Down([DSC-Local holding down])
+  
+```
+
+Flowchart for DSC - Locally-initiated transaction DSC-RSP pending state. The process starts at 'DSC-Local DSC-RSP pending' and branches into six paths: SF DSC-REQ Lost, Timeout T7, SF Change-Remote [ CM only ], SF Delete-Remote, SF Delete-Local, and DSC-RSP. Each path leads to specific state transitions and timer management, eventually returning to 'DSC-Local DSC-RSP pending' or ending in 'DSC-Local End' or 'DSC-Local holding down'.
+
+Figure 11-43 – DSC – Locally-initiated transaction DSC-RSP pending state flow diagram
+
+![State flow diagram for DSC - Locally-initiated transaction holding down state. The diagram starts at 'DSC-Local holding down' and branches into four paths: 1) SF Changed, SF Change-Remote, SF Delete-Remote leads to Stop T10 timer, then DSC Ended, then DSC-Local End. 2) Timeout T10 leads directly to DSC Ended. 3) SF Delete-Local leads to DSC-Local deleting service flow. 4) DSC-RSP leads to Saved DSC-ACK, then DSC ACK Lost, then DSC-Local holding down. A label J.122_F11-44 is at the bottom right.](2b04e13962c123370e90b83ab666b87f_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> DSC-Local_holding_down : DSC-Local holding down
+    DSC-Local_holding_down --> SF_Changed : SF Changed, SF Change-Remote, SF Delete-Remote
+    DSC-Local_holding_down --> Timeout_T10 : Timeout T10
+    DSC-Local_holding_down --> SF_Delete_Local : SF Delete-Local
+    DSC-Local_holding_down --> DSC_RSP : DSC-RSP
+
+    SF_Changed --> Stop_T10_timer : Stop T10 timer
+    Stop_T10_timer --> DSC_Ended : DSC Ended
+    Timeout_T10 --> DSC_Ended
+
+    DSC_Ended --> DSC_Local_End : DSC-Local End
+
+    SF_Delete_Local --> DSC_Local_deleting_service_flow : DSC-Local deleting service flow
+
+    DSC_RSP --> Saved_DSC_ACK : Saved DSC-ACK
+    Saved_DSC_ACK --> DSC_ACK_Lost : DSC ACK Lost
+    DSC_ACK_Lost --> DSC_Local_holding_down
+  
+```
+
+J.122\_F11-44
+
+State flow diagram for DSC - Locally-initiated transaction holding down state. The diagram starts at 'DSC-Local holding down' and branches into four paths: 1) SF Changed, SF Change-Remote, SF Delete-Remote leads to Stop T10 timer, then DSC Ended, then DSC-Local End. 2) Timeout T10 leads directly to DSC Ended. 3) SF Delete-Local leads to DSC-Local deleting service flow. 4) DSC-RSP leads to Saved DSC-ACK, then DSC ACK Lost, then DSC-Local holding down. A label J.122\_F11-44 is at the bottom right.
+
+**Figure 11-44 – DSC – Locally-initiated transaction holding down state flow diagram**
+
+![Flowchart for DSC - Locally-initiated transaction retries exhausted state flow diagram. The process starts at 'DSC-Local Retries Exhausted' and branches into four paths: Timeout T10, SF Delete-Remote, SF Delete-Local, and DSC-RSP. The DSC-RSP path includes an 'Okay?' decision leading to either 'Restore service flow QoS state' (No) or 'Modify Service Flow parameters' (Yes), eventually leading to 'DSC-ACK' and 'DSC-Local Holding Down'.](415e434818c86e65d50bb34de97ea0a3_img.jpg)
+
+```
+
+graph TD
+    Start([DSC-Local Retries Exhausted]) --> T10[Timeout T10]
+    Start --> SFDR[SF Delete-Remote]
+    Start --> SFDL[SF Delete-Local]
+    Start --> DSC_RSP[DSC-RSP]
+    
+    T10 --> DSC_Erred[DSC Erred]
+    SFDR --> StopT10[Stop T10 Timer]
+    SFDL --> DSC_Local_Deleting([DSC-Local Deleting Service Flow])
+    
+    DSC_Erred --> DSC_Ended[DSC Ended]
+    StopT10 --> DSC_Ended
+    DSC_Ended --> DSC_Local_End([DSC-Local End])
+    
+    DSC_RSP --> Okay{Okay?}
+    Okay -- No --> Restore[Restore service flow QoS state]
+    Okay -- Yes --> Modify[Modify Service Flow parameters]
+    
+    Restore --> DSC_Failed[DSC Failed]
+    DSC_Failed --> SetReject[Set Condition Code to 'reject-xxx']
+    
+    Modify --> DSC_Succeeded[DSC Succeeded]
+    DSC_Succeeded --> SetOkay[Set Condition Code to 'okay']
+    
+    SetReject --> DSC_ACK[DSC-ACK]
+    SetOkay --> DSC_ACK
+    
+    DSC_ACK --> SaveACK[Save transmitted DSC-ACK]
+    SaveACK --> DSC_Local_HoldingDown([DSC-Local Holding Down])
+  
+```
+
+Flowchart for DSC - Locally-initiated transaction retries exhausted state flow diagram. The process starts at 'DSC-Local Retries Exhausted' and branches into four paths: Timeout T10, SF Delete-Remote, SF Delete-Local, and DSC-RSP. The DSC-RSP path includes an 'Okay?' decision leading to either 'Restore service flow QoS state' (No) or 'Modify Service Flow parameters' (Yes), eventually leading to 'DSC-ACK' and 'DSC-Local Holding Down'.
+
+122\_F11-45
+
+Figure 11-45 – DSC – Locally-initiated transaction retries exhausted state flow diagram
+
+![State flow diagram for DSC - Locally-initiated transaction deleting service flow. The process starts with 'DSC-Local Deleting Service Flow', which branches into three paths: 'SF Deleted, SF Delete-Remote' leading to 'Stop T10 Timer' then 'DSC Ended' then 'DSC-Local End'; 'Timeout T10' leading to 'DSC Ended'; and 'DSC-RSP' leading to 'DSC ACK Lost' then 'DSC-Local Deleting Service Flow'.](8932612a402edc27c589bfa1f2c7de1b_img.jpg)
+
+```
+
+graph TD
+    Start([DSC-Local Deleting Service Flow]) --> SFDeleted[SF Deleted, SF Delete-Remote]
+    Start --> Timeout[Timeout T10]
+    Start --> DSC-RSP[DSC-RSP]
+    SFDeleted --> StopT10[Stop T10 Timer]
+    StopT10 --> DSC-Ended1[DSC Ended]
+    Timeout --> DSC-Ended2[DSC Ended]
+    DSC-Ended1 --> End([DSC-Local End])
+    DSC-Ended2 --> End
+    DSC-RSP --> DSC-ACK-Lost[DSC ACK Lost]
+    DSC-ACK-Lost --> End2([DSC-Local Deleting Service Flow])
+  
+```
+
+J.122\_F11-46
+
+State flow diagram for DSC - Locally-initiated transaction deleting service flow. The process starts with 'DSC-Local Deleting Service Flow', which branches into three paths: 'SF Deleted, SF Delete-Remote' leading to 'Stop T10 Timer' then 'DSC Ended' then 'DSC-Local End'; 'Timeout T10' leading to 'DSC Ended'; and 'DSC-RSP' leading to 'DSC ACK Lost' then 'DSC-Local Deleting Service Flow'.
+
+**Figure 11-46 – DSC – Locally-initiated transaction deleting service flow state flow diagram**
+
+![Flowchart for DSC - Remotely-initiated transaction begin state flow diagram. The process starts with 'DSC-Remote Begin', followed by 'DSC-REQ', a decision 'Okay?', and subsequent steps for 'No' and 'Yes' paths leading to 'DSC-RSP' and 'DSC-Remote DSC-ACK Pending'.](19582bb3a35dfc4bcab8f239c83c229a_img.jpg)
+
+```
+
+graph TD
+    Start([DSC-Remote Begin]) --> DSC-REQ[/DSC-REQ/]
+    DSC-REQ --> Okay{Okay?}
+    Okay -- No --> SetReject[Set Condition Code to 'reject-xxx']
+    Okay -- Yes --> Modify[Modify Service Flow parameters]
+    Modify --> SetOkay[Set Condition Code to 'okay']
+    SetReject --> DSC-RSP[/DSC-RSP/]
+    SetOkay --> DSC-RSP
+    DSC-RSP --> StartT8[Start T8 Timer]
+    StartT8 --> SaveRSP[Save transmitted DSC-RSP]
+    SaveRSP --> SetRetries[Set DSC-RSP Retries Available to 'DSx Response Retries']
+    SetRetries --> End([DSC-Remote DSC-ACK Pending])
+  
+```
+
+Flowchart for DSC - Remotely-initiated transaction begin state flow diagram. The process starts with 'DSC-Remote Begin', followed by 'DSC-REQ', a decision 'Okay?', and subsequent steps for 'No' and 'Yes' paths leading to 'DSC-RSP' and 'DSC-Remote DSC-ACK Pending'.
+
+J.122\_F11-47
+
+Figure 11-47 – DSC – Remotely-initiated transaction begin state flow diagram
+
+![Flowchart for DSC - Remotely-initiated transaction DSC-ACK pending state. The process starts at 'DSC-Remote DSC-ACK Pending' and branches into several paths: DSC-REQ, SF DSC-ACK Lost, Timeout T8, SF Delete-Remote, SF Delete-Local, DSC-ACK, and another DSC-ACK. Each path leads to specific actions like 'Stop T8 Timer', 'Start T10 Timer', 'DSC-Remote Deleting Service Flow', 'DSC-Remote End', 'DSC-Remote Holding Down', or 'DSC-Remote DSC-ACK Pending'.](381b701baf194171a242aa2b1741f4a9_img.jpg)
+
+```
+
+graph TD
+    Start([DSC-Remote DSC-ACK Pending]) --> DSC_REQ[/DSC-REQ/]
+    Start --> SF_DACK_Lost[/SF DSC-ACK Lost/]
+    Start --> Timeout_T8[/Timeout T8/]
+    Start --> SF_Delete_Remote[/SF Delete-Remote/]
+    Start --> SF_Delete_Local[/SF Delete-Local/]
+    Start --> DACK_1[/DSC-ACK/]
+    Start --> DACK_2[/DSC-ACK/]
+
+    DSC_REQ --> Retries_Avail_1{Retries Available?}
+    Retries_Avail_1 -- No --> DSC_REQ
+    Retries_Avail_1 -- Yes --> Saved_DSC_RSP_1[/Saved DSC-RSP/]
+    Saved_DSC_RSP_1 --> Start_T8_1[Start T8 Timer]
+    Start_T8_1 --> Decrement_DSC_RSP[Decrement DSC-RSP  
+Retries Available]
+    Decrement_DSC_RSP --> Start
+
+    SF_DACK_Lost --> Retries_Avail_2{Retries Available?}
+    Timeout_T8 --> Retries_Avail_2
+
+    Retries_Avail_2 -- No --> Stop_T8_1[Stop T8 Timer]
+    Stop_T8_1 --> DSC_Erred[/DSC Erred/]
+    DSC_Erred --> DSC_Ended[/DSC Ended/]
+    DSC_Ended --> DSC_Remote_End([DSC-Remote End])
+
+    Retries_Avail_2 -- Yes --> Saved_DSC_RSP_2[/Saved DSC-RSP/]
+    Saved_DSC_RSP_2 --> Start_T8_2[Start T8 Timer]
+    Start_T8_2 --> Decrement_DSC_RSP
+
+    SF_Delete_Remote --> Stop_T8_2[Stop T8 Timer]
+    Stop_T8_2 --> DSC_Erred
+
+    SF_Delete_Local --> Stop_T8_3[Stop T8 Timer]
+    Stop_T8_3 --> Start_T10_1[Start T10 Timer]
+    Start_T10_1 --> DSC_Remote_Deleting([DSC-Remote Deleting Service Flow])
+
+    DACK_1 --> Stop_T8_4[Stop T8 Timer]
+    Stop_T8_4 --> Okay_1{Okay?}
+    Okay_1 -- No --> Restore_SF[Restore service flow]
+    Restore_SF --> DSC_Failed[/DSC Failed/]
+    DSC_Failed --> Start_T8_3[Start T8 Timer]
+    Start_T8_3 --> DSC_Remote_Holding_Down_1([DSC-Remote Holding Down])
+
+    Okay_1 -- Yes --> DSC_Succeeded_1[/DSC Succeeded/]
+    DSC_Succeeded_1 --> Start_T8_3
+
+    DACK_2 --> Stop_T8_5[Stop T8 Timer]
+    Stop_T8_5 --> Okay_2{Okay?}
+    Okay_2 -- Yes --> DSC_Succeeded_2[/DSC Succeeded/]
+    DSC_Succeeded_2 --> Start_T8_4[Start T8 Timer]
+    Start_T8_4 --> DSC_Remote_Holding_Down_2([DSC-Remote Holding Down])
+  
+```
+
+Flowchart for DSC - Remotely-initiated transaction DSC-ACK pending state. The process starts at 'DSC-Remote DSC-ACK Pending' and branches into several paths: DSC-REQ, SF DSC-ACK Lost, Timeout T8, SF Delete-Remote, SF Delete-Local, DSC-ACK, and another DSC-ACK. Each path leads to specific actions like 'Stop T8 Timer', 'Start T10 Timer', 'DSC-Remote Deleting Service Flow', 'DSC-Remote End', 'DSC-Remote Holding Down', or 'DSC-Remote DSC-ACK Pending'.
+
+Figure 11-48 – DSC – Remotely-initiated transaction DSC-ACK pending state flow diagram
+
+![State flow diagram for DSC - Remotely-initiated transaction holding down. The process starts at 'DSC-Remote Holding Down' and branches into four paths: 'SF Changed, SF Deleted, SF Delete-Remote' leading to 'Stop T8 Timer' then 'DSC Ended' then 'DSC-Remote End'; 'Timeout T8' leading directly to 'DSC Ended'; 'SF Delete-Local, SF Change-Remote' leading to 'DSC-ACK' then 'DSC-Remote Holding Down'; and 'DSC-ACK' leading directly to 'DSC-Remote Holding Down'.](9c2536121e6816795e5aad3dd13371e3_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> DSC-Remote_Holding_Down : DSC-Remote Holding Down
+    DSC-Remote_Holding_Down --> SF_Changed : SF Changed, SF Deleted, SF Delete-Remote
+    DSC-Remote_Holding_Down --> Timeout_T8 : Timeout T8
+    DSC-Remote_Holding_Down --> SF_Delete_Local : SF Delete-Local, SF Change-Remote
+    DSC-Remote_Holding_Down --> DSC_ACK : DSC-ACK
+    SF_Changed --> Stop_T8_Timer : Stop T8 Timer
+    Stop_T8_Timer --> DSC_Ended : DSC Ended
+    DSC_Ended --> DSC-Remote_End : DSC-Remote End
+    Timeout_T8 --> DSC_Ended
+    SF_Delete_Local --> DSC_ACK
+    DSC_ACK --> DSC-Remote_Holding_Down
+  
+```
+
+State flow diagram for DSC - Remotely-initiated transaction holding down. The process starts at 'DSC-Remote Holding Down' and branches into four paths: 'SF Changed, SF Deleted, SF Delete-Remote' leading to 'Stop T8 Timer' then 'DSC Ended' then 'DSC-Remote End'; 'Timeout T8' leading directly to 'DSC Ended'; 'SF Delete-Local, SF Change-Remote' leading to 'DSC-ACK' then 'DSC-Remote Holding Down'; and 'DSC-ACK' leading directly to 'DSC-Remote Holding Down'.
+
+J.122\_F11-49
+
+Figure 11-49 – DSC – Remotely-initiated transaction holding down state flow diagram
+
+![State flow diagram for DSC - Remotely-initiated transaction deleting service flow. The process starts at 'DSC-Remote Deleting Service Flow' and branches into three paths: 'SF Deleted, SF Delete-Remote' leading to 'Stop T10 Timer' then 'DSC Ended' then 'DSC-Remote End'; 'Timeout T10' leading directly to 'DSC Ended'; and 'DSC-REQ, DSC-ACK' leading to 'DSC-Remote Deleting Service Flow'.](07ccb21f70641797dd02a891ced72b7e_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> DSC-Remote_Deleting_Service_Flow : DSC-Remote Deleting Service Flow
+    DSC-Remote_Deleting_Service_Flow --> SF_Deleted : SF Deleted, SF Delete-Remote
+    DSC-Remote_Deleting_Service_Flow --> Timeout_T10 : Timeout T10
+    DSC-Remote_Deleting_Service_Flow --> DSC_REQ_ACK : DSC-REQ, DSC-ACK
+    SF_Deleted --> Stop_T10_Timer : Stop T10 Timer
+    Stop_T10_Timer --> DSC_Ended : DSC Ended
+    DSC_Ended --> DSC-Remote_End : DSC-Remote End
+    Timeout_T10 --> DSC_Ended
+    DSC_REQ_ACK --> DSC-Remote_Deleting_Service_Flow
+  
+```
+
+State flow diagram for DSC - Remotely-initiated transaction deleting service flow. The process starts at 'DSC-Remote Deleting Service Flow' and branches into three paths: 'SF Deleted, SF Delete-Remote' leading to 'Stop T10 Timer' then 'DSC Ended' then 'DSC-Remote End'; 'Timeout T10' leading directly to 'DSC Ended'; and 'DSC-REQ, DSC-ACK' leading to 'DSC-Remote Deleting Service Flow'.
+
+J.122\_F11-50
+
+Figure 11-50 – DSC – Remotely-initiated transaction deleting service flow state flow diagram
+
+#### 11.4.4 Dynamic service deletion
+
+Any service flow can be deleted with the dynamic service deletion (DSD) messages. When a service flow is deleted, all resources associated with it are released, including classifiers and PHS. However, if a primary service flow of a CM is deleted, that CM is de-registered and MUST re-register. Also, if a service flow that was provisioned during registration is deleted, the
+
+provisioning information for that service flow is lost until the CM re-registers. However, the deletion of a provisioned service flow MUST NOT cause a CM to re-register. Therefore, care should be taken before deleting such service flows.
+
+#### 11.4.4.1 CM-initiated dynamic service deletion
+
+A CM wishing to delete an upstream and/or a downstream service flow generates a delete request to the CMTS using a dynamic service deletion request message (DSD-REQ). The CMTS removes the service flow(s) and generates a response using a dynamic service deletion response message (DSD-RSP). Only one upstream and/or one downstream service flow can be deleted per DSD-Request.
+
+![Sequence diagram for CM-initiated dynamic service deletion. The diagram shows two participants: CM and CMTS. The CM sends a DSD-REQ message to the CMTS. The CMTS receives the DSD-REQ, verifies the CM is the 'owner' of the service flow(s), and deletes the service flow(s). The CMTS then sends a DSD-RSP message back to the CM, which receives it.](e4b6ed98fad76b79cb9f85783e13086a_img.jpg)
+
+```
+
+sequenceDiagram
+    participant CM
+    participant CMTS
+    Note left of CM: Service flow(s) no longer needed  
+Delete service flow(s)
+    CM->>CMTS: Send DSD-REQ
+    Note right of CMTS: Receive DSD-REQ  
+Verify CM is service flow(s) 'owner'  
+Delete service flow(s)
+    CMTS->>CM: Send DSD-RSP
+    Note left of CM: Receive DSD-RSP
+  
+```
+
+Sequence diagram for CM-initiated dynamic service deletion. The diagram shows two participants: CM and CMTS. The CM sends a DSD-REQ message to the CMTS. The CMTS receives the DSD-REQ, verifies the CM is the 'owner' of the service flow(s), and deletes the service flow(s). The CMTS then sends a DSD-RSP message back to the CM, which receives it.
+
+Figure 11-51 – Dynamic service deletion initiated from CM
+
+#### 11.4.4.2 CMTS-initiated dynamic service deletion
+
+A CMTS wishing to delete an upstream and/or a downstream dynamic service flow generates a delete request to the associated CM using a dynamic service deletion request message (DSD-REQ). The CM removes the service flow(s) and generates a response using a dynamic service deletion response message (DSD-RSP). Only one upstream and/or one downstream service flow can be deleted per DSD-Request.
+
+![Sequence diagram for CMTS-initiated dynamic service deletion. The diagram shows two participants: CM and CMTS. The CMTS determines the associated CM for the service flow(s), then sends a DSD-REQ message to the CM. The CM receives the DSD-REQ, deletes the service flow(s), and sends a DSD-RSP message back to the CMTS, which receives it.](4599d7b27f6bd8041758d322232455d0_img.jpg)
+
+```
+
+sequenceDiagram
+    participant CM
+    participant CMTS
+    Note right of CMTS: Service flow(s) no longer needed  
+Delete service flow(s)  
+Determine associated CM for this service flow(s)
+    CMTS->>CM: Send DSD-REQ
+    Note left of CM: Receive DSD-REQ  
+Delete service flow(s)
+    CM->>CMTS: Send DSD-RSP
+    Note right of CMTS: Receive DSD-RSP
+  
+```
+
+Sequence diagram for CMTS-initiated dynamic service deletion. The diagram shows two participants: CM and CMTS. The CMTS determines the associated CM for the service flow(s), then sends a DSD-REQ message to the CM. The CM receives the DSD-REQ, deletes the service flow(s), and sends a DSD-RSP message back to the CMTS, which receives it.
+
+Figure 11-52 – Dynamic service deletion initiated from CMTS
+
+### 11.4.4.3 Dynamic service deletion state transition diagrams
+
+![Flowchart of the DSD – Locally-initiated transaction begin state flow diagram.](e13d2ed373946df26f71416c7386045d_img.jpg)
+
+```
+graph TD;
+    A([DSD-Local  
+Begin]) --> B[/SF Delete/];
+    B --> C[Disable  
+service flow];
+    C --> D[DSD-REQ];
+    D --> E[Start T7 Timer];
+    E --> F[Save transmitted  
+DSD-REQ];
+    F --> G[Set DSD-REQ  
+Retries Available  
+to 'DSx Request  
+Retries'];
+    G --> H([DSD-Local  
+DSD-RSP  
+Pending]);
+```
+
+The flowchart illustrates the sequence of operations for a locally-initiated dynamic service deletion (DSD) transaction. It begins with a terminal state 'DSD-Local Begin', followed by an input/output step 'SF Delete', then a process step 'Disable service flow'. The next steps are 'DSD-REQ', 'Start T7 Timer', 'Save transmitted DSD-REQ', and 'Set DSD-REQ Retries Available to 'DSx Request Retries''. The process concludes at the terminal state 'DSD-Local DSD-RSP Pending'.
+
+J.122\_F11-53
+
+Flowchart of the DSD – Locally-initiated transaction begin state flow diagram.
+
+**Figure 11-53 – DSD – Locally-initiated transaction begin state flow diagram**
+
+![Flowchart for DSD-Locally-initiated transaction DSD-RSP pending state. It starts at 'DSD-Local DSD-RSP Pending' and branches into four paths: 'SF DSD-REQ Lost' (leading to 'Retries Available?' and then 'Saved DSD-REQ' or back to pending), 'Timeout T7' (leading to 'Retries Available?' and then 'Saved DSD-REQ', 'Start T7 Timer', 'Decrement DSD-REQ Retries Available', or 'DSD Ended'), 'SF Delete-Remote' (leading to 'Stop T7 Timer'), and 'DSD-RSP' (leading to 'Stop T7 Timer', 'DSD Succeeded', 'Start T7 Timer', and 'DSD-Local Holding Down').](2b817d2912f95cb0ab93ff621a3f0a5b_img.jpg)
+
+```
+
+graph TD
+    Start([DSD-Local DSD-RSP Pending]) --> SF_DSD_REQ_Lost[/SF DSD-REQ Lost/]
+    Start --> Timeout_T7[/Timeout T7/]
+    Start --> SF_Delete_Remote[/SF Delete-Remote/]
+    Start --> DSD_RSP[/DSD-RSP/]
+    
+    SF_DSD_REQ_Lost --> Retries_Available_1{Retries Available?}
+    Retries_Available_1 -- Yes --> Saved_DSD_REQ_1[/Saved DSD-REQ/]
+    Retries_Available_1 -- No --> Pending_1([DSD-Local DSD-RSP Pending])
+    
+    Timeout_T7 --> Retries_Available_2{Retries Available?}
+    Retries_Available_2 -- Yes --> Saved_DSD_REQ_2[/Saved DSD-REQ/]
+    Retries_Available_2 -- No --> DSD_Errer[/DSD Erred/]
+    Saved_DSD_REQ_2 --> Start_T7_Timer_2[Start T7 Timer]
+    Start_T7_Timer_2 --> Decrement_DSD_REQ_Retries[Decrement DSD-REQ Retries Available]
+    Decrement_DSD_REQ_Retries --> Pending_2([DSD-Local DSD-RSP Pending])
+    DSD_Errer --> DSD_Ended_2[/DSD Ended/]
+    DSD_Ended_2 --> DSD_Local_End([DSD-Local End])
+    
+    SF_Delete_Remote --> Stop_T7_Timer_1[Stop T7 Timer]
+    
+    DSD_RSP --> Stop_T7_Timer_2[Stop T7 Timer]
+    Stop_T7_Timer_2 --> DSD_Succeeded[/DSD Succeeded/]
+    DSD_Succeeded --> Start_T7_Timer_3[Start T7 Timer]
+    Start_T7_Timer_3 --> DSD_Local_Holding_Down_1([DSD-Local Holding Down])
+    
+    J122_F11-54((J.122_F11-54))
+  
+```
+
+Flowchart for DSD-Locally-initiated transaction DSD-RSP pending state. It starts at 'DSD-Local DSD-RSP Pending' and branches into four paths: 'SF DSD-REQ Lost' (leading to 'Retries Available?' and then 'Saved DSD-REQ' or back to pending), 'Timeout T7' (leading to 'Retries Available?' and then 'Saved DSD-REQ', 'Start T7 Timer', 'Decrement DSD-REQ Retries Available', or 'DSD Ended'), 'SF Delete-Remote' (leading to 'Stop T7 Timer'), and 'DSD-RSP' (leading to 'Stop T7 Timer', 'DSD Succeeded', 'Start T7 Timer', and 'DSD-Local Holding Down').
+
+Figure 11-54 – DSD – Locally-initiated transaction DSD-RSP pending state flow diagram
+
+![Flowchart for DSD-Locally-initiated transaction holding down state. It starts at 'DSD-Local Holding Down' and branches into three paths: 'Timeout T7' (leading to 'DSD Ended' and 'DSD-Local End'), 'SF Deleted' (leading to 'DSD-Local Holding Down'), and 'DSD-RSP' (leading to 'DSD Succeeded' and 'DSD-Local Holding Down').](0bc9c064e5f4893fbd3ba3fbf1abc76c_img.jpg)
+
+```
+
+graph TD
+    Start([DSD-Local Holding Down]) --> Timeout_T7[/Timeout T7/]
+    Start --> SF_Deleted[/SF Deleted/]
+    Start --> DSD_RSP[/DSD-RSP/]
+    
+    Timeout_T7 --> DSD_Ended[/DSD Ended/]
+    DSD_Ended --> DSD_Local_End([DSD-Local End])
+    
+    SF_Deleted --> DSD_Local_Holding_Down_1([DSD-Local Holding Down])
+    
+    DSD_RSP --> DSD_Succeeded[/DSD Succeeded/]
+    DSD_Succeeded --> DSD_Local_Holding_Down_2([DSD-Local Holding Down])
+    
+    J122_F11-55((J.122_F11-55))
+  
+```
+
+Flowchart for DSD-Locally-initiated transaction holding down state. It starts at 'DSD-Local Holding Down' and branches into three paths: 'Timeout T7' (leading to 'DSD Ended' and 'DSD-Local End'), 'SF Deleted' (leading to 'DSD-Local Holding Down'), and 'DSD-RSP' (leading to 'DSD Succeeded' and 'DSD-Local Holding Down').
+
+Figure 11-55 – DSD – Locally-initiated transaction holding down state flow diagram
+
+![Flowchart of DSD - Remotely-initiated transaction begin state flow diagram](2f260472f70ca4f19e8e5ede6e88f394_img.jpg)
+
+```
+graph TD; A([DSD-Remote begin]) --> B[/DSD-REQ/]; B --> C[Disable service flow]; C --> D[/DSD Succeeded/]; D --> E[/DSD-RSP/]; E --> F[Start T10 timer]; F --> G[Save transmitted DSD-RSP]; G --> H([DSD-Remote holding down])
+```
+
+The flowchart illustrates the state flow for a DSD - Remotely-initiated transaction begin. It starts with a rounded rectangle labeled 'DSD-Remote begin', which points down to a chevron shape labeled 'DSD-REQ'. This is followed by a rectangle labeled 'Disable service flow', which points to another chevron shape labeled 'DSD Succeeded'. The next step is a chevron shape labeled 'DSD-RSP', followed by a rectangle labeled 'Start T10 timer', and then a rectangle labeled 'Save transmitted DSD-RSP'. The final step is a rounded rectangle labeled 'DSD-Remote holding down'.
+
+Flowchart of DSD - Remotely-initiated transaction begin state flow diagram
+
+J.122\_F11-56
+
+**Figure 11-56 – DSD – Remotely-initiated transaction begin state flow diagram**
+
+![Flowchart of DSD - Remotely-initiated transaction holding down state flow diagram. The process starts with 'DSD-Remote Holding Down' (oval), which branches into three paths: 1) 'SF Deleted' (parallelogram) -> 'Stop T10 Timer' (rectangle) -> 'DSD Ended' (parallelogram) -> 'DSD-Remote End' (oval). 2) 'Timeout T10' (parallelogram) -> 'DSD Ended' (parallelogram). 3) 'DSD-REQ' (parallelogram) -> 'Saved DSD-RSP' (parallelogram) -> 'DSD-Remote Holding Down' (oval). A label 'J.122_F11-57' is at the bottom right.](ac5084f644988289daf6c0a519f232ba_img.jpg)
+
+```
+
+graph TD
+    Start([DSD-Remote Holding Down]) --> SF[SF Deleted]
+    Start --> T10[Timeout T10]
+    Start --> REQ[DSD-REQ]
+    SF --> Stop[Stop T10 Timer]
+    Stop --> Ended[DSD Ended]
+    T10 --> Ended
+    REQ --> Saved[Saved DSD-RSP]
+    Saved --> End([DSD-Remote End])
+    Ended --> End
+  
+```
+
+Flowchart of DSD - Remotely-initiated transaction holding down state flow diagram. The process starts with 'DSD-Remote Holding Down' (oval), which branches into three paths: 1) 'SF Deleted' (parallelogram) -> 'Stop T10 Timer' (rectangle) -> 'DSD Ended' (parallelogram) -> 'DSD-Remote End' (oval). 2) 'Timeout T10' (parallelogram) -> 'DSD Ended' (parallelogram). 3) 'DSD-REQ' (parallelogram) -> 'Saved DSD-RSP' (parallelogram) -> 'DSD-Remote Holding Down' (oval). A label 'J.122\_F11-57' is at the bottom right.
+
+Figure 11-57 – DSD – Remotely-initiated transaction holding down state flow diagram
+
+## 11.4.5 Dynamically changing downstream and/or upstream channels
+
+### 11.4.5.1 DCC general operation
+
+At any time after registration, the CMTS MAY use the DCC-REQ to direct the CM to change its downstream and/or upstream channel. The CMTS MUST be capable of performing DCC operations to trigger upstream and/or downstream channel changes within a MAC domain and between MAC domains. Physical layer conditions permitting, the CMTS MUST be capable of executing such channel changes using all initialization techniques (see clause 11.4.5.1.2). This may be done for load balancing (as described in clause 11.4.5.6), noise avoidance or other reasons that are beyond the scope of this Recommendation. In addition, the CMTS MUST support DCC operations triggered via SNMP (see [DOCS5]). Figures 11-58 through 11-61 show the procedure that MUST be followed by the CMTS when performing a dynamic channel change. Figures 11-62 through 11-65 show the corresponding procedure that MUST be followed by a CM when performing a dynamic channel change.
+
+The DCC command can be used to change only the upstream frequency, only the downstream frequency, or both the upstream and downstream frequencies. When only the upstream or only the downstream frequency is changed, the change is typically within a MAC domain. When both the upstream and downstream frequencies are changed, the change may be within a MAC domain, or between MAC domains.
+
+The upstream channel ID SHOULD be unique between the old and new channels. In this context, the old channel refers to the channel that the CM was on before the jump, and the new channel refers to the channel that the CM is on after the jump.
+
+Upon synchronizing with the new upstream and/or downstream channel, the CM MUST use the technique specified in the DCC-REQ initialization technique TLV, if present, to determine if it should perform re-initialization, only ranging, or neither. If this TLV is not present in DCC-REQ, the CM MUST re-initialize its MAC on the new channel assignment (refer to clause 11.2). If the CM has been instructed to re-initialize, then the CMTS MUST NOT wait for a DCC-RSP to occur on the new channel.
+
+If the CM is being moved within a MAC domain, a re-initialization may not be required. If the CM is being moved between MAC domains, a re-initialization may be required. Re-initializing, if requested, is done with the new upstream and downstream channel assignments. It includes obtaining upstream parameters, establishing IP connectivity, establishing time of day, transferring operational parameters, registering, and initializing baseline privacy. If re-initialization is performed, the CM MUST NOT send a DCC-RSP on the new channel.
+
+The decision to re-range is based upon the CMTS's knowledge of any path diversity that may exist between the old and new channels, or if any of the fundamental parameters of the upstream or downstream channel, such as modulation rate, modulation type, or mini-slot size, have changed.
+
+When DCC-REQ does not involve re-initialization or re-ranging, the design goal of the CM will typically be to minimize the disruption of traffic to the end user. To achieve this goal, a CM MAY choose to continue to use QoS resources (such as bandwidth grants) on its current channel after receiving a DCC-REQ and before actually executing the channel change. The CM might also need this time to flush internal queues or reset state machines prior to changing channels.
+
+The CM MAY continue to use QoS resources on the old channel, including the transmission and reception of packets, after sending a DCC-RSP (depart) message and prior to the actual jump. The CM MAY use QoS resources on the new channel, including the transmission and reception of packets, after the jump and prior to sending a DCC-RSP (arrive) message. The CMTS MUST NOT use the DCC-RSP (depart) message to remove QoS resources on the old channel. The CMTS MUST NOT wait for a DCC-RSP (arrive) message on the new channel before allowing QoS resources to be used. This provision is to allow the unsolicited grant service to be used on the old and new channel with a minimum amount of disruption when changing channels.
+
+The CMTS MUST hold the QoS resources on the old channel until a time of T13 has passed after the last DCC-REQ that was sent, or until it can internally confirm the presence of the CM on the new channel assignment. The CM MUST execute the departure from the old channel before the expiry of T13. The CM MAY continue to use QoS resources on the old channel after responding with DCC-RSP and before the expiry of T13.
+
+If the CM is commanded to perform initial or station maintenance or to use the channel directly, the destination CMTS MUST hold the QoS resources on the new channel until a time of T15 has passed after the last DCC-REQ was sent if the CM has not yet been detected on the new channel. If the CM is commanded to re-initialize the MAC, then QoS resources are not reserved on the destination CMTS, and T15 does not apply. If, in the process of a dynamic channel change with a non-zero initialization technique, the CMTS detects that the CM has re-initialized the MAC before completing the channel change, the CMTS MAY de-allocate the resources that were previously allocated to the modem on the new channel before the expiration of T15.
+
+The T15 timer represents the maximum time period for the CM to complete the move to the destination CMTS, and is based on the TLV encodings (i.e., initialization technique TLV) included in the DCC-REQ message and the local configuration of the destination CMTS.
+
+The destination CMTS SHOULD calculate and limit T15 based on internal policy according to the guidelines in clause 11.4.5.1.1.
+
+If the initialization technique of initial ranging is utilized and if the CM arrives after T15 has passed, attempting to use resources on the new channel that have been removed (ranging or requesting bandwidth on a SID that has been deleted), the CMTS MUST send a ranging abort to the CM in order to cause the DCC transaction to fail, ensuring that the CM and CMTS states remain in sync.
+
+When a CM is moved between downstream channels on different IP subnets using initialization techniques other than re-initialize the MAC, a network connectivity issue may occur because no DHCP process is indicated as part of the DCC operation. The CM MAY implement a
+
+vendor-specific feature to deal with this situation. The CMTS SHOULD take this issue into account when sending a DCC-REQ and SHOULD direct the CM to use the appropriate initialization technique TLV to ensure no IP connectivity loss as a result of DCC.
+
+Once the CM changes channels, all previous outstanding bandwidth requests made via the request IE or request/data IE are invalidated, and the CM MUST re-request bandwidth on the new channel. In the case of unsolicited grant service in the upstream, the grants are implicit with the QoS reservations, and do not need to be re-requested.
+
+#### 11.4.5.1.1 Derivation of T15 timer
+
+The maximum value noted for the T15 timer denotes the maximum amount of time that the CMTS should reserve resources on the new channel. This value is not to be used to represent acceptable performance.
+
+The equation below describes the method for calculating the value of T15.
+
+$$T15 = CmJumpTime + CmtsRxRngReq$$
+
+Each of the variables in the equation calculating the T15 timer is explained in the table below.
+
+| Variable     | Explanation and value                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
+|--------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| CmJumpTime   | <p>This is the CM's indication to the CMTS of when it intends to start the jump and how long it will take to jump. For a downstream change, it includes the time for the CM to synchronize to the downstream parameters on the destination channel, such as QAM symbol timing, FEC framing and MPEG framing. It incorporates CM housecleaning on the old channel. It also incorporates one T11 period for the CM to process and receive the DCC-REQ message. This optional value is computed by the CM and returned in DCC-RSP (depart).</p> <p>If the CM does not specify the jump time TLVs, then the destination CMTS assumes that the value is 1.3 seconds. This recognizes the fact that the CM may continue to use the old channel until the expiry of the T13 timer.</p> <p>If the CM specifies the jump time TLVs, then the destination CMTS uses the specified value.</p>             |
+| CmtsRxRngReq | <p>This variable represents the time for the CM to receive and use a ranging opportunity, and for the CMTS to receive and process the RNG-REQ.</p> <p>For the initialization technique of use directly, this value is two times the CMTS time period between unicast ranging opportunities plus 20-40 milliseconds for MAP and RNG-REQ transmission time and CMTS RNG-REQ processing time.</p> <p>For the initialization technique of station maintenance, this value is two times the CMTS time period between unicast ranging opportunities plus 20-40 milliseconds for MAP and RNG-REQ transmission time and CMTS RNG-REQ processing time.</p> <p>For the initialization technique of initial maintenance, this value is 30 seconds. Because the variables involved in initial maintenance are not strictly under the control of the CMTS, the computation of this factor is uncertain.</p> |
+
+The minimum value of the T15 timer is four seconds; this was derived by quadrupling the value of the T13 timer. The maximum value of the T15 timer is 35 seconds.
+
+#### 11.4.5.1.2 Initialization technique
+
+There are many factors that drive the selection of an initialization technique when commanding a dynamic channel change. While it is desirable to provide the minimum of interruption to existing
+
+QoS services such as voice over IP or streaming video sessions, a CM will not be able to successfully execute a channel change given an initialization technique that is unsuitable for the cable plant conditions. In some cases, a CM will impair the new channel given an unsuitable initialization technique. For instance, consider the use of initialization technique 4 (use the new channel(s) directly without re-initializing or performing initial or station maintenance) when there is a significant difference in propagation delay between the old and new channel. Not only will the CM be unable to communicate with the CMTS after the channel change, but its transmissions may also interfere with the transmissions of other CMs using the channel.
+
+Careful consideration must be given to the selection of an initialization technique. Some restrictions are listed below. This list is not exhaustive, but is intended to prevent the use of a particular initialization technique under conditions where its use could prevent the CM from successfully executing the channel change. Packets may be dropped under some conditions during channel changes; applications that are running over the DOCSIS path should be able to cope with the loss of packets that may occur during the time that the CM changes channels.
+
+If a CM performs a channel change without performing a re-initialization (as defined in clause 8.3.20.1.3), all the configuration variables of the CM MUST remain constant (BPI keys, IP address, classifiers, PHS Rules, etc.), with the exception of the configuration variables which are explicitly changed by the DCC-REQ message encodings (as defined in clauses 8.3.20.1.1 through 8.3.20.1.7). The CM will not be aware of any configuration changes other than the ones that have been supplied in the DCC command, so consistency in provisioning between the old and new channels is important. Note that regardless of the initialization technique, the CPE will not be aware of any configuration changes and will continue to use its existing IP address.
+
+#### **11.4.5.1.2.1 Initialization technique zero**
+
+The use of initialization technique 0 (re-initialize the MAC) results in the longest interruption of service. The CMTS MUST signal the use of this technique when QoS resources will not be reserved on the new channel(s).
+
+#### **11.4.5.1.2.2 Initialization technique one**
+
+The use of initialization technique 1 (broadcast initial ranging) may also result in a lengthy interruption of service. However, this interruption of service is mitigated by the reservation of QoS resources on the new channel(s). The service interruption can be further reduced if the CMTS supplies downstream parameter sub-TLVs and the UCD substitution TLV in the DCC-REQ in addition to providing more frequent initial ranging opportunities on the new channel.
+
+#### **11.4.5.1.2.3 Initialization technique two**
+
+The use of initialization technique 2 (unicast initial ranging) offers the possibility of only a slight interruption of service.
+
+In order to use this technique, the CMTS MUST:
+
+- Synchronize timestamps (and downstream symbol clocks for S-CDMA support) across the downstream channels involved, and specify SYNC substitution sub-TLV with a value of 1 if the downstream channel is changing.
+- Include the UCD substitution in the DCC message if the upstream channel is changing.
+
+However, the CMTS MUST NOT use this technique if:
+
+- The DCC-REQ message requires the CM to switch between S-CDMA and TDMA.
+- Propagation delay differences between the old and new channels will cause the CM burst timing to exceed the ranging accuracy requirements of clause 6.2.19.1.
+- Attenuation or frequency response differences between the old and new upstream channels will cause the received power at the CMTS to be outside the limits of reliable reception.
+
+#### 11.4.5.1.2.4 Initialization technique three
+
+The use of initialization technique 3 (initial ranging or periodic ranging) offers the possibility of only a slight interruption of service. This value might be used when there is uncertainty when the CM may execute the DCC command and thus a chance that it might miss station maintenance slots. However, the CMTS MUST NOT use this technique if the conditions for using techniques 1 and 2 are not completely satisfied.
+
+#### 11.4.5.1.2.5 Initialization technique four
+
+The use of initialization technique 4 (use the new channel without re-initialization or ranging) results in the least interruption of service.
+
+In order to use this technique, the CMTS MUST:
+
+- Synchronize timestamps (and downstream symbol clocks for S-CDMA support) across the downstream channels involved and specify SYNC substitution sub-TLV with a value of 1 if the downstream channel is changing.
+- Include the UCD substitution in the DCC message if the upstream channel is changing.
+
+However, the CMTS MUST NOT use this technique if:
+
+- The CM is operating in S-CDMA mode and any of the following parameters are changing:
+  - Modulation rate;
+  - S-CDMA mode enable;
+  - S-CDMA US ratio numerator 'M';
+  - S-CDMA US ratio numerator 'N';
+  - Downstream channel.
+- The DCC-REQ message requires the CM to switch between S-CDMA and TDMA.
+- Attenuation or frequency response differences between the old and new upstream channels will cause the received power at the CMTS to change by more than 6 dB.
+- Propagation delay differences between the old and new channels will cause the CM burst timing to exceed the ranging accuracy requirements of clause 6.2.19.1.
+- Micro-reflections on the new upstream channel will result in an unacceptable PER (greater than 1%) with the pre-equalizer coefficients set to the initial setting (refer to clause 6.2.15).
+
+The CMTS SHOULD NOT use initialization technique 4 when the new or old channel is S-CDMA and the modulation rate is changing.
+
+#### 11.4.5.2 DCC exception conditions
+
+If a CM issues a DSA-REQ or DSC-REQ for more resources, and the CMTS needs to do a DCC to obtain those resources, the CMTS will reject the DSA or DSC command without allocating any resources to the CM. The CMTS includes a confirmation code of "reject-temporary-DCC" (refer to clause C.1.3.1) in the DSC-RSP message to indicate that the new resources will not be available until a DCC is received. The CMTS will then follow the DSA or DSC transaction with a DCC transaction.
+
+After the CM jumps to a new channel and completes the DCC transaction, the CM retries the DSA or DSC command. If the CM has not changed channels after the expiry of T14, as measured from the time that the CM received DSA-RSP or DSC-RSP from the CMTS, then the CM MAY retry the resource request.
+
+If the CMTS needs to change channels in order to satisfy a resource request other than a CM-initiated DSA or DSC command, then the CMTS should execute the DCC command first, and then issue a DSA or DSC command.
+
+If the provisioning system default is to specify the upstream channel ID, the downstream frequency, and/or a downstream channel list in the configuration file, care should be taken when using DCC, particularly when using initialization technique 0 (re-initialize MAC). If a CMTS does a DCC with re-initialize, the configuration file could cause the CM to come back to the original channel. This would cause an infinite loop.
+
+The CMTS MUST NOT issue a DCC command if the CMTS has previously issued a DSA, or DSC command, and that command is still outstanding. The CMTS MUST NOT issue a DCC command if the CMTS is still waiting for a DSA-ACK or DSC-ACK from a previous CM initiated DSA-REQ or DSC-REQ command.
+
+The CMTS MUST NOT issue a DSA or DSC command if the CMTS has previously issued a DCC command, and that command is still outstanding.
+
+If the CMTS issues a DCC-REQ command and the CM simultaneously issues a DSA-REQ or DSC-REQ, then the CMTS command takes priority. The CMTS responds with a confirmation code of "reject-temporary" (refer to clause C.1.3.1). The CM proceeds with executing the DCC command.
+
+If the CM is unable to achieve communications with a CMTS on the new channel(s), it MUST return to the previous channel(s) and re-initialize its MAC. The previous channel assignment represents a known good operating point which should speed up the re-initialization process. Also, returning to the previous channel provides a more robust operational environment for the CMTS to find a CM that fails to connect on the new channel(s).
+
+If the CMTS sends a DCC-REQ and does not receive a DCC-RSP within time T11, it MUST retransmit the DCC-REQ up to a maximum of "DCC-REQ Retries" (Annex B) before declaring the transaction a failure. Note that if the DCC-RSP was lost in transit and the CMTS retries the DCC-REQ, the CM may have already changed channels.
+
+If the CM sends a DCC-RSP on the new channel and does not receive a DCC-ACK from the CMTS within time T12, it MUST retry the DCC-RSP up to a maximum of "DCC-RSP retries" (Annex B).
+
+If the CM receives a DCC-REQ with the upstream channel ID TLV, if present, equal to the current upstream channel ID, and the downstream frequency TLV, if present, is equal to the current downstream frequency, then the CM MUST consider the DCC-REQ as a redundant command. The remaining DCC-REQ TLV parameters MUST NOT be executed, and the CM MUST return a DCC-RSP, with a confirmation code of "reject-already-there", to the CMTS (refer to clause C.4.1).
+
+If a DOCS 2.0-enabled CM is moved from a type 1 channel to a type 2 channel via a DCC using an initialization technique other than re-initialize the MAC, the CM MUST operate in 2.0 mode on the destination channel, basing its requests on IUCs 9 and 10 instead of IUCs 5 and 6. If a CM in which DOCS 2.0 is disabled in registration is moved from a type 1 channel to a type 2 channel via a DCC with initialization technique other than re-initialize the MAC, the CM MUST continue to base its requests on the destination channel on IUCs 5 and 6. A CM in which DOCSIS 2.0 is disabled in registration MUST consider a type 3 channel to be invalid for any DCC using an initialization technique other than re-initialize the MAC.
+
+If the CM is moved via a DCC using the initialization technique of re-initialize the MAC, the previous 2.0 enable setting is not applicable. If DOCS 2.0 was previously disabled and the target upstream channel is type 2 or type 3, the 2.0 disable setting is discarded and the CM MUST use the target upstream channel; however, after re-initialization, the CM MUST operate in the 2.0 mode defined in the config file acquired in the re-initialization process.
+
+### 11.4.5.3 DCC state transition diagrams
+
+![Flowchart showing the dynamic channel changing process from the CMTS perspective, split into 'Previous CMTS Operational' and 'New CMTS Operational' paths.](886a88caad59e8f8b1cf54c72e8adf4a_img.jpg)
+
+```
+
+graph TD
+    subgraph Previous_CMTS_Operational
+        P1([Previous CMTS Operational]) --> P2[/Channel Change Required/]
+        P1 --> P3[/DCC-RSP <conf code>/]
+        P2 --> P4{Initialization Technique = Reinitialize the MAC?}
+        P4 -- No --> P5[/DCC beginning (to new CMTS), including DCC-REQ parameters/]
+        P4 -- Yes --> P6[Set DCC-REQ retry counter to 0]
+        P3 --> P7[/ERROR: Unknown DCC transaction/]
+        P7 --> P8([Previous CMTS Operational])
+        P5 --> P6
+        P6 --> P9[/DCC-REQ/]
+        P9 --> P10[/Start T11 Start T13/]
+        P10 --> P11([Previous CMTS DCC-RSP (depart) Pending])
+    end
+
+    subgraph New_CMTS_Operational
+        N1([New CMTS Operational]) --> N2[/DCC beginning (from old CMTS), including DCC-REQ parameters/]
+        N1 --> N3[/DCC-RSP <conf code>/]
+        N2 --> N4[/Prepare new channel(s) with any appropriate resource assignments/]
+        N4 --> N5[/Start T15/]
+        N5 --> N6([New CMTS DCC-RSP (arrive) Pending])
+        N3 --> N7[/ERROR: Unknown DCC transaction/]
+        N7 --> N8([New CMTS Operational])
+        N6 --> N9[/Other event from old CMTS/]
+        N9 --> N10[Ignore the event.]
+        N10 --> N11([New CMTS Operational])
+    end
+
+    P11 --> P12((DCC CMTS A))
+    P12 --> P9
+  
+```
+
+Note that the new CMTS is not informed of the DCC if the CM will Reset the MAC, and it will ignore other events that are sent by the old CMTS in other states.
+
+J.122\_F11-58
+
+Flowchart showing the dynamic channel changing process from the CMTS perspective, split into 'Previous CMTS Operational' and 'New CMTS Operational' paths.
+
+Figure 11-58 – Dynamically changing channels: CMTS view, part 1
+
+![Flowchart illustrating the CM-REQ processing logic for dynamically changing channels from the CM-REQ side. The process starts with 'Previous CM-REQ DCC-RSP (reject) Pending'. It branches into four main paths: 1) DCC-RSP (depart) leads to Stop T11, then DCC-RSP CM Jump Time (to new CM-REQ), ending at 'Previous CM-REQ DCC T13 Pending'. 2) DCC-RSP (reject-<reason>) leads to Stop T11, then ERROR: DCC-REQ rejected <reason>, then Stop T13, then DCC Aborted (to new CM-REQ), ending at 'Previous CM-REQ Operational'. 3) Timeout T11 leads to a decision 'DCC-REQ Retries Exhausted?'. If Yes, it leads to ERROR: CM not responding, then Stop T13, then DCC Aborted (to new CM-REQ), ending at 'Previous CM-REQ Operational'. If No, it leads to Increment DCC-REQ retries counter, ending at 'DCC CM-REQ A'. 4) CM Arrived (from new CM-REQ) leads to Stop T11 Stop T13, then Remove old channel resource assignments, then ERROR: DCC-RSP (depart) lost, ending at 'Previous CM-REQ Operational'.](7ac0d7b4763471d7c6dee8a2ce125b6a_img.jpg)
+
+```
+
+graph TD
+    Start([Previous CM-REQ DCC-RSP (reject) Pending]) --> DCC-RSP-depart[DCC-RSP (depart)]
+    Start --> DCC-RSP-reject[DCC-RSP (reject-<reason>)]
+    Start --> Timeout-T11[Timeout T11]
+    Start --> CM-Arrived[CM Arrived (from new CM-REQ)]
+
+    DCC-RSP-depart --> Stop-T11-1[Stop T11]
+    Stop-T11-1 --> DCC-RSP-CM-Jump[DCC-RSP CM Jump Time (to new CM-REQ)]
+    DCC-RSP-CM-Jump --> Previous-CM-REQ-DCC-T13-Pending([Previous CM-REQ DCC T13 Pending])
+
+    DCC-RSP-reject --> Stop-T11-2[Stop T11]
+    Stop-T11-2 --> ERROR-rejected[ERROR: DCC-REQ rejected <reason>]
+    ERROR-rejected --> Stop-T13-1[Stop T13]
+    Stop-T13-1 --> DCC-Aborted-1[DCC Aborted (to new CM-REQ)]
+    DCC-Aborted-1 --> Previous-CM-REQ-Operational-1([Previous CM-REQ Operational])
+
+    Timeout-T11 --> Retries-Exhausted{DCC-REQ Retries Exhausted?}
+    Retries-Exhausted -- Yes --> ERROR-not-responding[ERROR: CM not responding]
+    ERROR-not-responding --> Stop-T13-2[Stop T13]
+    Stop-T13-2 --> DCC-Aborted-2[DCC Aborted (to new CM-REQ)]
+    DCC-Aborted-2 --> Previous-CM-REQ-Operational-2([Previous CM-REQ Operational])
+
+    Retries-Exhausted -- No --> Increment-Retries[Increment DCC-REQ retries counter]
+    Increment-Retries --> DCC-CM-REQ-A((DCC CM-REQ A))
+
+    CM-Arrived --> Stop-T11-T13[Stop T11 Stop T13]
+    Stop-T11-T13 --> Remove-Old-Assignments[Remove old channel resource assignments.]
+    Remove-Old-Assignments --> ERROR-lost[ERROR: DCC-RSP (depart) lost]
+    ERROR-lost --> Previous-CM-REQ-Operational-3([Previous CM-REQ Operational])
+  
+```
+
+Flowchart illustrating the CM-REQ processing logic for dynamically changing channels from the CM-REQ side. The process starts with 'Previous CM-REQ DCC-RSP (reject) Pending'. It branches into four main paths: 1) DCC-RSP (depart) leads to Stop T11, then DCC-RSP CM Jump Time (to new CM-REQ), ending at 'Previous CM-REQ DCC T13 Pending'. 2) DCC-RSP (reject-) leads to Stop T11, then ERROR: DCC-REQ rejected , then Stop T13, then DCC Aborted (to new CM-REQ), ending at 'Previous CM-REQ Operational'. 3) Timeout T11 leads to a decision 'DCC-REQ Retries Exhausted?'. If Yes, it leads to ERROR: CM not responding, then Stop T13, then DCC Aborted (to new CM-REQ), ending at 'Previous CM-REQ Operational'. If No, it leads to Increment DCC-REQ retries counter, ending at 'DCC CM-REQ A'. 4) CM Arrived (from new CM-REQ) leads to Stop T11 Stop T13, then Remove old channel resource assignments, then ERROR: DCC-RSP (depart) lost, ending at 'Previous CM-REQ Operational'.
+
+J.122\_F11-59
+
+Figure 11-59 – Dynamically changing channels: CM-REQ view, part 2
+
+![Flowchart showing the CMTS view for dynamically changing channels. It starts with 'Previous CMTS DCC T13 Pending' and branches into four paths: 'Timeout T13', 'CM Arrived (from new CMTS)', 'CM no longer present on old channel' (marked with 1), and 'DCC-RSP (<conf code>)'. The first three paths lead to 'Stop T13' and then 'Remove old channel resource assignments.', ending at 'Previous CMTS Operational'. The fourth path leads to 'ERROR: Unknown DCC transaction' and back to 'Previous CMTS DCC T13 Pending'. A note indicates that the mechanism for event 1 is vendor-specific.](2399254baf1cd3a8e04cf5313b4d9b8f_img.jpg)
+
+```
+
+graph TD
+    Start([Previous CMTS DCC T13 Pending]) --> T13[Timeout T13]
+    Start --> CM[CM Arrived from new CMTS]
+    Start --> CM2[CM no longer present on old channel 1]
+    Start --> DCC[DCC-RSP <conf code>]
+    T13 --> Stop[Stop T13]
+    CM --> Stop
+    CM2 --> Stop
+    Stop --> Remove[Remove old channel resource assignments.]
+    Remove --> End([Previous CMTS Operational])
+    DCC --> Error[ERROR: Unknown DCC transaction]
+    Error --> Start
+  
+```
+
+① The mechanism to determine this event is vendor-specific.
+
+J.122\_F11-60
+
+Flowchart showing the CMTS view for dynamically changing channels. It starts with 'Previous CMTS DCC T13 Pending' and branches into four paths: 'Timeout T13', 'CM Arrived (from new CMTS)', 'CM no longer present on old channel' (marked with 1), and 'DCC-RSP ()'. The first three paths lead to 'Stop T13' and then 'Remove old channel resource assignments.', ending at 'Previous CMTS Operational'. The fourth path leads to 'ERROR: Unknown DCC transaction' and back to 'Previous CMTS DCC T13 Pending'. A note indicates that the mechanism for event 1 is vendor-specific.
+
+Figure 11-60 – Dynamically changing channels: CMTS view, part 3
+
+![Flowchart for 'New CMTS DCC-RSP (arrive) Pending' state. It branches into five paths: 1) 'DCC-RSP CM Jump Time (from old CMTS)' leads to 'Store Jump Time' -> 'Restart T15' -> back to 'New CMTS DCC-RSP (arrive) Pending'. 2) 'CM detected on new channel' (marked with 1) leads to 'Start T10' -> 'CM Arrived (to old CMTS)' -> 'New CMTS DCC Hold-down'. 3) 'DCC-RSP (arrive)' leads to 'DCC-ACK' -> 'Stop T15' -> 'Start T10' -> 'CM Arrived (to old CMTS)' -> 'New CMTS DCC Hold-down'. 4) 'Timeout T15' leads to 'ERROR: CM not arriving' -> 'Remove new channel resource assignments.' -> 'New CMTS Operational'. 5) 'DCC Aborted (from old CMTS)' leads to 'ERROR: DCC Aborted' -> 'Stop T15' -> 'Remove new channel resource assignments.' -> 'New CMTS Operational'. A note indicates that step 1 is CMTS-specific and can include receiving RNG-REQ or bandwidth requests.](5772ffa3b9089a69e25df5ec289ead55_img.jpg)
+
+```
+
+graph TD
+    Start([New CMTS DCC-RSP  
+(arrive) Pending]) --> DCC-RSP-Jump[DCC-RSP  
+CM Jump Time  
+(from old CMTS)]
+    Start --> CM-Detected[CM detected  
+on new channel]
+    Start --> DCC-RSP-Arrive[DCC-RSP  
+(arrive)]
+    Start --> Timeout-T15[Timeout T15]
+    Start --> DCC-Aborted[DCC Aborted  
+(from old CMTS)]
+
+    DCC-RSP-Jump --> Store-Jump[Store Jump Time]
+    Store-Jump --> Restart-T15[Restart T15]
+    Restart-T15 --> Start
+
+    CM-Detected --> Start-T10-1[Start T10]
+    DCC-RSP-Arrive --> DCC-ACK-1[DCC-ACK]
+    DCC-ACK-1 --> Stop-T15-1[Stop T15]
+    Stop-T15-1 --> Start-T10-1
+    Start-T10-1 --> CM-Arrived[CM Arrived  
+(to old CMTS)]
+    CM-Arrived --> DCC-Hold-down-1([New CMTS DCC  
+Hold-down])
+
+    Timeout-T15 --> Error-Not-Arriving[ERROR:  
+CM not arriving]
+    Error-Not-Arriving --> Remove-Resources[Remove new  
+channel resource  
+assignments.]
+    Remove-Resources --> CMTS-Operational-1([New CMTS  
+Operational])
+
+    DCC-Aborted --> Error-Aborted[ERROR:  
+DCC Aborted]
+    Error-Aborted --> Stop-T15-2[Stop T15]
+    Stop-T15-2 --> Remove-Resources
+    Remove-Resources --> CMTS-Operational-1
+  
+```
+
+① Determination of this is CMTS-specific, but can include receiving RNG-REQ or bandwidth requests from the CM on the new channel.
+
+Flowchart for 'New CMTS DCC-RSP (arrive) Pending' state. It branches into five paths: 1) 'DCC-RSP CM Jump Time (from old CMTS)' leads to 'Store Jump Time' -> 'Restart T15' -> back to 'New CMTS DCC-RSP (arrive) Pending'. 2) 'CM detected on new channel' (marked with 1) leads to 'Start T10' -> 'CM Arrived (to old CMTS)' -> 'New CMTS DCC Hold-down'. 3) 'DCC-RSP (arrive)' leads to 'DCC-ACK' -> 'Stop T15' -> 'Start T10' -> 'CM Arrived (to old CMTS)' -> 'New CMTS DCC Hold-down'. 4) 'Timeout T15' leads to 'ERROR: CM not arriving' -> 'Remove new channel resource assignments.' -> 'New CMTS Operational'. 5) 'DCC Aborted (from old CMTS)' leads to 'ERROR: DCC Aborted' -> 'Stop T15' -> 'Remove new channel resource assignments.' -> 'New CMTS Operational'. A note indicates that step 1 is CMTS-specific and can include receiving RNG-REQ or bandwidth requests.
+
+![Flowchart for 'New CMTS DCC Hold-down' state. It branches into two paths: 1) 'Timeout T10' leads to 'New CMTS Operational'. 2) 'DCC-RSP (arrive)' leads to 'DCC-ACK' -> 'New CMTS DCC Hold-down'.](e817de1b2f803560e39d541c3966532b_img.jpg)
+
+```
+
+graph TD
+    Start([New CMTS DCC  
+Hold-down]) --> Timeout-T10[Timeout T10]
+    Start --> DCC-RSP-Arrive[DCC-RSP  
+(arrive)]
+
+    Timeout-T10 --> CMTS-Operational([New CMTS  
+Operational])
+
+    DCC-RSP-Arrive --> DCC-ACK[DCC-ACK]
+    DCC-ACK --> Start
+  
+```
+
+Flowchart for 'New CMTS DCC Hold-down' state. It branches into two paths: 1) 'Timeout T10' leads to 'New CMTS Operational'. 2) 'DCC-RSP (arrive)' leads to 'DCC-ACK' -> 'New CMTS DCC Hold-down'.
+
+J.122\_F11-61
+
+Figure 11-61 – Dynamically changing channels: CMTS view, part 4
+
+![Flowchart for dynamically changing channels: CM view, part 1. The process starts with 'CM Operational', followed by 'DCC-REQ', 'Parse DCC-REQ', and a decision 'DCC-REQ valid?'. If 'No', it sends 'DCC-RSP (reject-<reason>)', then 'ERROR: Bad CMTS DCC <reason>', and returns to 'CM Operational'. If 'Yes', it checks 'Already using US and DS channels?'. If 'Yes', it sends 'DCC-RSP (reject-already-there)', then 'ERROR: Bad CMTS DCC already-there', and returns to 'CM Operational'. If 'No', it checks 'Can jump be made?'. If 'No', it sends 'DCC-RSP (reject-<reason>)', then 'ERROR: DCC-REQ denied', and returns to 'CM Operational'. If 'Yes', it sends 'DCC-RSP (depart)', then 'Clean up internal queues and other housekeeping', then 'Apply Id substitutions, store UCD from DCC-REQ (if present)', and ends at 'DCC CM A'.](0363a872d994d4b7d4c2de7820793d76_img.jpg)
+
+```
+
+graph TD
+    Start([CM Operational]) --> DCC_REQ[/DCC-REQ/]
+    DCC_REQ --> Parse[Parse DCC-REQ]
+    Parse --> Valid{DCC-REQ valid?}
+    Valid -- No --> Reject1[/DCC-RSP (reject-<reason>)/]
+    Reject1 --> Error1[/ERROR: Bad CMTS DCC <reason>/]
+    Error1 --> CM_Op1([CM Operational])
+    Valid -- Yes --> AlreadyUsing{Already using US and DS channels?}
+    AlreadyUsing -- Yes --> Reject2[/DCC-RSP (reject-already-there)/]
+    Reject2 --> Error2[/ERROR: Bad CMTS DCC already-there/]
+    Error2 --> CM_Op2([CM Operational])
+    AlreadyUsing -- No --> CanJump{Can jump be made?}
+    CanJump -- No --> Reject3[/DCC-RSP (reject-<reason>)/]
+    Reject3 --> Error3[/ERROR: DCC-REQ denied/]
+    Error3 --> CM_Op3([CM Operational])
+    CanJump -- Yes --> Depart[/DCC-RSP (depart)/]
+    Depart --> CleanUp[Clean up internal queues and other housekeeping]
+    CleanUp --> IdSubs[Apply Id substitutions, store UCD from DCC-REQ (if present)]
+    IdSubs --> End((DCC CM A))
+  
+```
+
+Flowchart for dynamically changing channels: CM view, part 1. The process starts with 'CM Operational', followed by 'DCC-REQ', 'Parse DCC-REQ', and a decision 'DCC-REQ valid?'. If 'No', it sends 'DCC-RSP (reject-)', then 'ERROR: Bad CMTS DCC ', and returns to 'CM Operational'. If 'Yes', it checks 'Already using US and DS channels?'. If 'Yes', it sends 'DCC-RSP (reject-already-there)', then 'ERROR: Bad CMTS DCC already-there', and returns to 'CM Operational'. If 'No', it checks 'Can jump be made?'. If 'No', it sends 'DCC-RSP (reject-)', then 'ERROR: DCC-REQ denied', and returns to 'CM Operational'. If 'Yes', it sends 'DCC-RSP (depart)', then 'Clean up internal queues and other housekeeping', then 'Apply Id substitutions, store UCD from DCC-REQ (if present)', and ends at 'DCC CM A'.
+
+J.122\_F11-62
+
+Figure 11-62 – Dynamically changing channels: CM view, part 1
+
+![Flowchart for dynamically changing channels: CM view, part 2. The process starts at DCC CM A and proceeds through a series of decision diamonds and process blocks to reach CM DCC-ACK pending. The flowchart includes checks for downstream changes, MAC re-initialization, UCD storage, SYNC acquisition, MAP cache, and ranging. It ends with a response handling loop.](1dd97d21e745e17aa9bf424cac55737d_img.jpg)
+
+```
+
+graph TD
+    Start((DCC CM A)) --> D1{Downstream Change?}
+    D1 -- Yes --> P1(CM DCC Downstream Change)
+    D1 -- No --> D2{Initialization technique =  
+Re-init the MAC?}
+    D2 -- Yes --> P2[Reset the MAC]
+    P2 --> P3(Obtain Upstream Parameters ①)
+    D2 -- No --> D3{Valid UCD for  
+target upstream  
+stored?}
+    D3 -- No --> P4(CM DCC Acquire UCD)
+    D3 -- Yes --> D4{Wait for SYNCs?}
+    D4 -- Yes --> P5(CM DCC Acquire SYNC)
+    D4 -- No --> D5{Valid MAP in cache?}
+    D5 -- No --> P6(CM DCC Acquire MAP)
+    D5 -- Yes --> D6{Initialization  
+technique =  
+Use-Directly?}
+    D6 -- No --> P7(CM DCC Ranging)
+    D6 -- Yes --> P8[Set DCC-RSP  
+(arrive) retry  
+counter to 0]
+    P8 --> End((DCC CM B))
+    P4 --> D4
+    P5 --> D5
+    P6 --> D6
+    P7 --> P8
+    End --> P9[/DCC-RSP  
+(arrive)/]
+    P9 --> P10[Start T12]
+    P10 --> EndState(CM DCC-ACK pending)
+  
+```
+
+J.122\_F11-63
+
+① The state "Obtain Upstream Parameters" links to the state machine in Figure 11-1.
+
+Flowchart for dynamically changing channels: CM view, part 2. The process starts at DCC CM A and proceeds through a series of decision diamonds and process blocks to reach CM DCC-ACK pending. The flowchart includes checks for downstream changes, MAC re-initialization, UCD storage, SYNC acquisition, MAP cache, and ranging. It ends with a response handling loop.
+
+**Figure 11-63 – Dynamically changing channels: CM view, part 2**
+
+![Flowchart for dynamically changing channels - CM view, part 3. It shows five parallel processes: CM DCC Downstream Change, CM DCC Acquire UCD, CM DCC Acquire SYNC, CM DCC Acquire MAP, and CM DCC Ranging. Each process has a decision point leading to either a return to the main diagram or a CM DCC Failed state. Callouts 1 and 2 provide additional details for the UCD and Ranging steps respectively.](ad9b0c8d0d3fc421b0dbc2ecc61376f4_img.jpg)
+
+```
+
+graph TD
+    subgraph Path1 [CM DCC Downstream Change]
+        P1_1([CM DCC Downstream Change]) --> P1_2[Change tuner, attempt downstream lock (using hints provided by CMTS in DCC-REQ, if any)]
+        P1_2 --> P1_3{Successful lock?}
+        P1_3 -- No --> P1_4([CM DCC Failed])
+        P1_3 -- Yes --> P1_5({Return to main diagram})
+    end
+
+    subgraph Path2 [CM DCC Acquire UCD]
+        P2_1([CM DCC Acquire UCD]) --> P2_2[Wait for valid UCD for target upstream channel (for expiry of T1)]
+        P2_2 --> P2_3{UCD acquired?}
+        P2_3 -- No --> P2_4([CM DCC Failed])
+        P2_3 -- Yes --> P2_5({Return to main diagram})
+    end
+
+    subgraph Path3 [CM DCC Acquire SYNC]
+        P3_1([CM DCC Acquire SYNC]) --> P3_2[Wait for a SYNC message (up to Lost SYNC Interval).]
+        P3_2 --> P3_3{SYNC acquired?}
+        P3_3 -- No --> P3_4([CM DCC Failed])
+        P3_3 -- Yes --> P3_5({Return to main diagram})
+    end
+
+    subgraph Path4 [CM DCC Acquire MAP]
+        P4_1([CM DCC Acquire MAP]) --> P4_2[Wait for a MAP message.]
+        P4_2 --> P4_3{MAP acquired?}
+        P4_3 -- No --> P4_4([CM DCC Failed])
+        P4_3 -- Yes --> P4_5({Return to main diagram})
+    end
+
+    subgraph Path5 [CM DCC Ranging]
+        P5_1([CM DCC Ranging]) --> P5_2[Perform ranging as required (initial/station).]
+        P5_2 --> P5_3{Ranging Success?}
+        P5_3 -- No --> P5_4([CM DCC Failed])
+        P5_3 -- Yes --> P5_5({Return to main diagram})
+    end
+
+    Callout1((1)) -.-> P2_2
+    Callout2((2)) -.-> P5_2
+  
+```
+
+① a) If DOCSIS 2.0 is enabled, a valid UCD describes either a type 1, 2 or 3 channel.  
+b) If DOCSIS 2.0 is NOT enabled, a valid UCD describes a type 1 or type 2 channel.
+
+② See Figures 11-6 and 11-7 for details.
+
+J.122\_F11-64
+
+Flowchart for dynamically changing channels - CM view, part 3. It shows five parallel processes: CM DCC Downstream Change, CM DCC Acquire UCD, CM DCC Acquire SYNC, CM DCC Acquire MAP, and CM DCC Ranging. Each process has a decision point leading to either a return to the main diagram or a CM DCC Failed state. Callouts 1 and 2 provide additional details for the UCD and Ranging steps respectively.
+
+**Figure 11-64 – Dynamically changing channels – CM view, part 3**
+
+![Flowchart for dynamically changing channels - CM view, part 4. The diagram shows two main paths: one for a successful DCC-ACK and one for a DCC failure. The successful path starts at 'CM DCC-ACK pending', branches into 'Timeout T12' and 'DCC-ACK'. 'Timeout T12' leads to 'DCC-RSP retries exhausted?'. If 'No', it goes to 'Increment DCC-RSP (arrive) retry counter' then 'DCC CM B'. If 'Yes', it goes to 'ERROR: DCC-ACK not received'. 'DCC-ACK' leads to 'Parse DCC-ACK' then 'DCC-ACK valid?'. If 'Yes', it goes to 'Stop T12'. Both 'Stop T12' and 'ERROR: DCC-ACK not received' lead to 'CM Operational'. 'DCC-ACK valid?' if 'No', goes to 'ERROR: Bad CMDS DCC-ACK' then back to 'CM DCC-ACK pending'. The failure path starts at 'CM DCC Failed', goes to 'ERROR: DCC failed <reason>', then 'Return to old upstream/downstream.', then 'Reset the MAC', and finally 'Obtain Upstream Parameters'. A note indicates that 'Obtain Upstream Parameters' links to the state machine in Figure 11-1. Reference J.122_F11-65 is also present.](1a1c6e97fdffe8ffed7b997b7e682d3c_img.jpg)
+
+```
+
+graph TD
+    Start([CM DCC-ACK pending]) --> T12[Timeout T12]
+    Start --> DCC_ACK[DCC-ACK]
+    T12 --> Retries{DCC-RSP retries exhausted?}
+    Retries -- No --> Increment[Increment DCC-RSP (arrive) retry counter]
+    Increment --> CM_B((DCC CM B))
+    Retries -- Yes --> ErrorNotReceived[ERROR: DCC-ACK not received]
+    DCC_ACK --> Parse[Parse DCC-ACK]
+    Parse --> Valid{DCC-ACK valid?}
+    Valid -- Yes --> StopT12[Stop T12]
+    Valid -- No --> ErrorBadACK[ERROR: Bad CMDS DCC-ACK]
+    ErrorBadACK --> Start
+    StopT12 --> CM_Op[CM Operational]
+    ErrorNotReceived --> CM_Op
+
+    CM_Failed([CM DCC Failed]) --> ErrorFailed[ERROR: DCC failed <reason>]
+    ErrorFailed --> ReturnOld[Return to old upstream/downstream.]
+    ReturnOld --> ResetMAC[Reset the MAC]
+    ResetMAC --> Upstream[Obtain Upstream Parameters]
+  
+```
+
+The state "Obtain Upstream Parameters" links to the state machine in Figure 11-1. J.122\_F11-65
+
+Flowchart for dynamically changing channels - CM view, part 4. The diagram shows two main paths: one for a successful DCC-ACK and one for a DCC failure. The successful path starts at 'CM DCC-ACK pending', branches into 'Timeout T12' and 'DCC-ACK'. 'Timeout T12' leads to 'DCC-RSP retries exhausted?'. If 'No', it goes to 'Increment DCC-RSP (arrive) retry counter' then 'DCC CM B'. If 'Yes', it goes to 'ERROR: DCC-ACK not received'. 'DCC-ACK' leads to 'Parse DCC-ACK' then 'DCC-ACK valid?'. If 'Yes', it goes to 'Stop T12'. Both 'Stop T12' and 'ERROR: DCC-ACK not received' lead to 'CM Operational'. 'DCC-ACK valid?' if 'No', goes to 'ERROR: Bad CMDS DCC-ACK' then back to 'CM DCC-ACK pending'. The failure path starts at 'CM DCC Failed', goes to 'ERROR: DCC failed ', then 'Return to old upstream/downstream.', then 'Reset the MAC', and finally 'Obtain Upstream Parameters'. A note indicates that 'Obtain Upstream Parameters' links to the state machine in Figure 11-1. Reference J.122\_F11-65 is also present.
+
+Figure 11-65 – Dynamically changing channels – CM view, part 4
+
+#### 11.4.5.4 DCC performance
+
+The purpose of a DCC is to move the CM to a new upstream and/or downstream channel with little interruption of service. There are many factors that affect the performance of a DCC transaction including CM housecleaning, initialization technique and the number of TLV hints given by the current CMDS in the DCC-REQ message. Each of these factors is individually discussed in Table 11-1.
+
+**Table 11-1 – Factors affecting DCC performance**
+
+| TLV type                 | Value                                    | Explanation                                                                                                                                                                                                   |
+|--------------------------|------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Initialization technique | Absent or 0 re-initialize MAC            | There are no performance requirements in this case. The CM will arrive on the destination CMTS after initialization occurs.                                                                                   |
+|                          | 1 – Broadcast initial ranging            | There are low performance expectations in this case because many factors affect the performance, such as collisions and ranging backoff. The CM should arrive on the destination CMTS as quickly as possible. |
+|                          | 2 – Unicast initial ranging              | The DCC transaction SHOULD complete within 1.5 seconds after the start of jump.                                                                                                                               |
+|                          | 3 – Broadcast or unicast initial ranging | The CMTS does not know which ranging technique the CM will utilize. The CM should arrive on the destination CMTS as quickly as possible.                                                                      |
+|                          | 4 – Use channel directly                 | The DCC transaction SHOULD complete within one second after the start of jump.                                                                                                                                |
+| DS parameter             |                                          | The CMTS SHOULD include the downstream parameter TLVs for station maintenance and use directly initialization techniques that are expected to occur quickly.                                                  |
+| UCD substitution         |                                          | The CMTS MUST set the UCD substitution TLV according to clause 11.4.5.1.2.                                                                                                                                    |
+| SYNC substitution        |                                          | The CMTS MUST set the SYNC substitution TLV according to clause 11.4.5.1.2.                                                                                                                                   |
+| CM jump time             |                                          | The length of jump TLV SHOULD be less than one second for downstream channel changes that include the downstream parameter TLVs or for upstream-only channel changes.                                         |
+
+The DCC transaction is defined from the perspective of both the CM and the CMTS for the discussion on performance in Table 11-1. From the perspective of the CM, the DCC transaction begins when the CM receives the DCC-REQ message from the CMTS and completes when the CM receives the DCC-ACK message from the CMTS. From the perspective of the CMTS, the DCC transaction begins when the CMTS sends the DCC-REQ message to the CM and completes when the CMTS receives the DCC-RSP (arrive) message from the CM.
+
+When the DCC-REQ does not contain UCD substitution TLVs and/or specifies an initialization technique of initial maintenance, station maintenance or use directly, the destination CMTS SHOULD increase the probability that the CM will arrive quickly by using the CM jump time TLVs specified in the DCC-RSP (depart) to adjust the transmission of UCDs and ranging opportunities such that they coincide with the time when CM has estimated that it will arrive, and SHOULD increase the frequency of UCDs and/or ranging opportunities during this period.
+
+#### 11.4.5.5 Example operation
+
+##### 11.4.5.5.1 Example signalling
+
+Figure 11-66 shows an example of the use of DCC and its relation to the other DOCS MAC messages. In particular, this example describes a scenario where the CM attempts to allocate new resources with a DSA message. The CMTS temporarily rejects the request, tells the CM to change channels, and then the CM re-requests the resources. This example (not including all exception conditions) is described below. Refer to clause 11.2 for more detail.
+
+- An event occurs, such as the CM issuing a DSA-REQ message.
+
+- b) The CMTS decides that it needs the CM to change channels in order to service this resource request. The CMTS responds with a DSA-RSP message which includes a confirmation code of "reject-temporary-DCC" (refer to clause C.1.3.1) in the DSC-RSP message to indicate that the new resources are not available until a DCC is received. The CMTS now rejects any further DSA or DSC messages until the DCC command is executed.
+- c) The CMTS initiates QoS reservations on the new upstream and/or downstream channels. The QoS reservations include the new resource assignment along with all the current resource assignments assigned to the CM. In this example, both the upstream and downstream channels are changed.
+- d) To facilitate a near-seamless channel change, since the CMTS is not sure exactly when the CM will switch channels, the CMTS duplicates the downstream packet flow on the old and new downstream channels.
+- e) The CMTS issues a DCC-REQ command to the CM.
+- f) The CM cleans up its queues and state machines as appropriate, sends a DCC-RSP (depart), and changes channels.
+- g) If there was a downstream channel change, the CM synchronizes to the QAM symbol timing, synchronizes the FEC framing, and synchronizes with the MPEG framing.
+- h) If the CM has been instructed to re-initialize, it does so with the new upstream and/or downstream channel assignment. The CM exits from the flow of events described here, and enters the flow of events described in clause 11.2, starting with the recognition of a downstream SYNC message.
+- i) The CM searches for a UCD message unless it has been supplied with a copy.
+- j) The CM waits for a downstream SYNC message unless it has been instructed not to wait for one.
+- k) The CM collects MAP messages unless it already has them available in its cache.
+- l) The CM performs ranging if required by the initialization technique TLV.
+- m) The CM resumes normal data transmission with its new resource assignment.
+- n) The CM sends a DCC-RSP (arrive) message to the CMTS.
+- o) The CMTS responds with a DCC-ACK.
+- p) The CMTS removes the QoS reservations from the old channels. If the downstream packet flow was duplicated, the packet duplication would also be removed on the old downstream channel.
+- q) The CM re-issues its DSA-REQ command.
+- r) The CMTS reserves the requested resources and responds with a DSA-RSP.
+- s) The CM finishes with a DSA-ACK.
+
+![Sequence diagram illustrating the DCC example operational flow between DS #1, US #1, CM, US #2, and DS #2 within a CMTS. The diagram shows the exchange of data traffic, control messages (DSA-REQ, DSA-RSP, DSA-ACK, DCC-REQ, DCC-RSP, DCC-ACK), and various state transitions (Start T14, Start T11, T13, CM changes channels, Sync of QAM, FEC, MPEG, Optional re-initialize and exit from flow, Optional re-range, Release resources and stop traffic duplication).](d90f09fa97733a2cf12bb1ecaf8ddba8_img.jpg)
+
+The diagram illustrates the DCC example operational flow within a CMTS, involving five entities: DS #1, US #1, CM, US #2, and DS #2. The sequence of operations is as follows:
+
+- Data traffic** flows from DS #1 to CM and from CM to US #1.
+- DSA-REQ** is sent from US #1 to CM.
+- DSA-RSP** is sent from CM to US #1.
+- DSA-ACK** is sent from US #1 to CM.
+- Reserve resources and duplicate downstream traffic** occurs at US #2.
+- Data traffic** flows from DS #1 to CM and from CM to US #1.
+- Start T14** is initiated at CM.
+- Data traffic** flows from CM to US #2 and from US #2 to DS #2.
+- Data traffic** flows from DS #1 to CM and from CM to US #1.
+- DCC-REQ** is sent from US #1 to CM.
+- Start T11, T13** is initiated at US #1.
+- DCC-RSP** is sent from CM to US #1.
+- CM changes channels** occurs at CM.
+- Sync of QAM, FEC, MPEG** is sent from CM to DS #2.
+- Optional re-initialize and exit from flow** occurs at CM.
+- UCD (optional)**, **SYNC (optional)**, and **MAP (optional)** messages are sent from CM to DS #2.
+- Optional re-range** occurs at CM.
+- Data traffic** flows from DS #1 to CM and from CM to US #2.
+- DCC-RSP** is sent from CM to US #2.
+- Start T12** is initiated at CM.
+- DCC-ACK** is sent from US #2 to CM.
+- Release resources and stop traffic duplication** occurs at US #1.
+- DSA-REQ** is sent from US #2 to CM.
+- DSA-RSP** is sent from CM to US #2.
+- DSA-ACK** is sent from US #2 to CM.
+
+Sequence diagram illustrating the DCC example operational flow between DS #1, US #1, CM, US #2, and DS #2 within a CMTS. The diagram shows the exchange of data traffic, control messages (DSA-REQ, DSA-RSP, DSA-ACK, DCC-REQ, DCC-RSP, DCC-ACK), and various state transitions (Start T14, Start T11, T13, CM changes channels, Sync of QAM, FEC, MPEG, Optional re-initialize and exit from flow, Optional re-range, Release resources and stop traffic duplication).
+
+J.122\_F11-66
+
+Figure 11-66 – DCC example operational flow
+
+The states for the old and new CMTSs are shown as separate flow diagrams, since the old and new CMTS may be different. If the CMTSs are the same (e.g., the same MAC domain), the CMTS will need to run both sets of state machines concurrently.
+
+The flow diagrams show points where explicit signalling between the old and new CMTS is desirable, especially for near-seamless operation. The mechanism for this signalling is beyond the scope of this Recommendation.
+
+Note that the flow diagrams for both old and new CMTSs have been carefully crafted to handle many error conditions, such as:
+
+- If the CM does not respond to the DCC-REQ (or responds with a reject conf code) and does not move, then it will be allowed to remain on the old channel. Resources on the new channel will be released (old CMTS signals DCC aborted to the new CMTS).
+- If the CM DCC-RSP (depart) is lost, but the CM moves and arrives on the new CMTS, the new CMTS will signal that the CM has arrived to the old CMTS, allowing it to remove resources.
+- If the CM DCC-RSP (depart) is received and the CM DCC-RSP (arrive) is lost, but the new CMTS otherwise detects the presence of the CM, the DCC transaction is considered successful, and the CM is allowed to remain on the new channel.
+- If the CM DCC-RSP (depart) and (arrive) are lost, but the new CMTS otherwise detects the presence of the CM, the new CMTS will signal that the CM has arrived to the old CMTS, allowing it to remove resources, and the CM is allowed to remain on the new channel.
+- If the CM DCC-RSP (depart) is received, but the CM never arrives, the new CMTS will detect this and remove resources after T15 expires.
+- If the CM DCC-RSP (depart) is lost and the CM never arrives, the old CMTS will signal DCC aborted to the new CMTS, allowing it to remove resources. The old CMTS will use a different mechanism outside the scope of the DCC flow diagrams (such as ranging time-out) to remove resources on the old channels.
+- If the CMTS DCC-ACK is lost and the DCC-RSP retry counter is expired, the CM will log an error and continue to the operational state.
+
+There is a race condition that is not addressed in the flow diagrams; if the CM DCC-RSP (depart) is lost, the old CMTS will signal DCC aborted to the new CMTS. If the CM is in the process of moving, but has not yet arrived, the new CMTS will remove resources. This will prevent the CM from arriving successfully, unless it is able to complete the jump and arrive in approximately 1.2 seconds (3 retries of the DCC-REQ).
+
+#### 11.4.5.5.2 Example timing
+
+##### 11.4.5.5.2.1 Upstream and downstream change (use channel directly: CMTS supplies all TLV hints)
+
+In this example, the current CMTS sends a DCC-REQ message requesting that the CM switch both upstream and downstream channels. The DCC-REQ message includes the UCD substitution TLV, the SYNC substitution TLV, the downstream parameter TLVs, and the initialization technique TLV of 4 (use channel directly). The CM does not include the CM jump time TLV in the DCC-RSP.
+
+The destination CMTS has the following local parameters:
+
+- UCD interval: 1 s;
+- SYNC interval: 10 ms;
+- unicast ranging interval: 1 s.
+
+The destination CMTS calculates the T15 timer value. The definition of the formula used to determine T15 is shown below. The variables used in calculating T15 are explained in the table below.
+
+$$\begin{aligned} T15 &= CmJumpTime + CmtsRxRngReq \\ T15 &= 1.3 \text{ s} + (2.04 \text{ s}) = 3.34 \text{ s} \end{aligned}$$
+
+Since 3.34 s is less than the minimum value of the T15 timer, the CMTS sets the T15 timer to the minimum value for 4 seconds.
+
+| Variable     | Value                                                | Explanation                                                                                                                                                          |
+|--------------|------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| CmJumpTime   | 1.3 s                                                | Since the CM did not include the optional jump time TLV, the CMTS will use the default value of 1.3 seconds.                                                         |
+| CmtsRxRngReq | 2.02 s<br>$2 \times (1 \text{ sec}) + 40 \text{ ms}$ | Two times the CMTS time period between unicast ranging opportunities plus 20-40 milliseconds for MAP and RNG-REQ transmission time and CMTS RNG-REQ processing time. |
+
+The CM synchronizes to the downstream parameters on the new channel, applies the UCD supplied in the DCC-REQ, collects MAP messages on the new channel, and resumes normal data transmission on the destination channels. This occurs within the recommended performance of 1 second.
+
+#### 11.4.5.5.2.2 Upstream and downstream change (station maintenance: CMTS supplies no TLV hints)
+
+In this example, the current CMTS sends a DCC-REQ message requesting that the CM switch both upstream and downstream channels. The DCC-REQ message includes the initialization technique TLV of 2 (perform station maintenance). It also includes the required UCD substitution TLV and SYNC substitution sub-TLV. The CM does not include the CM jump time TLV in the DCC-RSP.
+
+The destination CMTS has the following local parameters:
+
+- UCD interval: 1 s;
+- SYNC interval: 10 ms;
+- unicast ranging interval: 5 s.
+
+The destination CMTS starts scheduling the CM immediately after it sends the DCC-REQ. The destination CMTS calculates the T15 timer value. The definition of the formula used to determine T15 is shown below. The variables used in calculating T15 are explained in the table below.
+
+$$\begin{aligned} T15 &= CmJumpTime + CmtsRxRngReq \\ T15 &= 1.3 \text{ s} + (10.04 \text{ s}) = 11.34 \text{ s} \end{aligned}$$
+
+| Variable     | Value                                               | Explanation                                                                                                                                                          |
+|--------------|-----------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| CmJumpTime   | 1.3 s                                               | Since the CM did not include the optional jump time TLV, the CMTS will use the default value of 1.3 seconds.                                                         |
+| CmtsRxRngReq | 10.04 s<br>$2 \times (5 \text{ s}) + 40 \text{ ms}$ | Two times the CMTS time period between unicast ranging opportunities plus 20-40 milliseconds for MAP and RNG-REQ transmission time and CMTS RNG-REQ processing time. |
+
+The CM should synchronize to the downstream parameters on the new channel, apply the UCD message provided, collect MAP messages on the destination channel without waiting for a downstream SYNC on the destination channel, perform station maintenance on the destination channel, and resume normal data transmission on the destination channels.
+
+These events occur in less than two seconds; this is within the acceptable performance criteria. The DCC transaction occurs within the recommended four second sum of CM jump time and two ranging intervals ( $0 + 2 \text{ s} = 2 \text{ s}$ ).
+
+#### **11.4.5.6 Autonomous load balancing**
+
+The CMTS MUST be capable of autonomous load balancing of CMs across all of its upstream and downstream channels using the DCC-REQ message, plant configuration permitting.
+
+Load balancing is manageable on a per-CM basis. The CMTS assigns each CM:
+
+- to a set of channels (a load balancing group) among which it can be moved by the CMTS;
+- a policy that governs if and when the CM can be moved;
+- a priority value that can be used by the CMTS in order to select CMs to move.
+
+##### **11.4.5.6.1 Load balancing groups**
+
+A load balancing group is a cluster of downstream and associated upstream physical channels among which modems can be autonomously load balanced. The operator must define load balancing groups to be consistent with the physical plant topology. Load balancing groups can be defined in order to cater for a specific class of service (e.g., residential or business).
+
+There are two types of load balancing groups, general load balancing groups and restricted load balancing groups. A restricted load balancing group is associated with a specific, provisioned set of cable modems, while general load balancing groups are open for CMs that are not provisioned into a restricted load balancing group. General load balancing groups can only be used when the plant topology allows the location of CMs to be unambiguously determined by the upstream channel on which they have registered. Restricted load balancing groups are used to accommodate a topology-specific or provisioning-specific restriction (such as a set of channels reserved for business customers). A restricted load balancing group could be a subset of one or more general load balancing groups.
+
+The CMTS MUST NOT associate an upstream channel with more than one general load balancing group. The CMTS can associate an upstream channel with any number of restricted load balancing groups (and potentially a single general load balancing group as well). The CMTS can associate a downstream channel with any number of load balancing groups, general and/or restricted.
+
+The CMTS assigns modems to general load balancing groups based on the upstream channel on which they are operating. The CMTS will assign a modem to a restricted load balancing group only if it is explicitly provisioned (via SNMP or configuration file TLV) to be a member of that group. The CMTS MUST NOT assign a CM to more than one load balancing group.
+
+When the CMTS receives a REG-REQ message, the CMTS MUST identify whether this CM has been assigned to a restricted load balancing group via SNMP (see [DOCS5]). If the CM is not assigned to a restricted load balancing group via SNMP, the CMTS MUST check for the presence of the CM load balancing group TLV in the REG-REQ message to identify assignment to a restricted load balancing group. If the CM is assigned to a restricted load balancing group via SNMP, the CMTS MUST ignore the CM load balancing group TLV in the REG-REQ message. If the REG-REQ contains a general load balancing group ID or a group ID that is not defined on the CMTS, the CMTS MUST ignore the group ID.
+
+If the CM has been assigned to a restricted load balancing group (either via SNMP or via the config file), and the CMTS detects that the CM is registering on a channel pair that is not associated with the assigned load balancing group, when registration completes, the CMTS MUST initiate a DCC-REQ to move the CM to the appropriate channel(s) in the assigned group. If the CM has not been assigned to a restricted load balancing group via SNMP or the config file, the CMTS MUST assign it to the general load balancing group that corresponds to the upstream channel on which it
+
+registered. If the upstream channel is not associated with a general load balancing group, the CMTS MUST NOT assign the CM to any load balancing group.
+
+As part of autonomous load balancing operations, the CMTS MUST adhere to the following restrictions:
+
+- The CMTS MUST NOT direct a CM to move to a channel outside the load balancing group to which it is assigned.
+- If a CM is not assigned to a load balancing group, the CMTS MUST NOT move the CM.
+- The CMTS MUST NOT move a DOCSIS 1.0 – or DOCSIS 1.1 – compliant CM, or a DOCSIS 2.0 – compliant CM that has 2.0 mode disabled, to a type 3 upstream channel.
+
+If, during normal operation, the CMTS is directed (via SNMP or otherwise) to move a CM to a channel that is outside the load balancing group to which it is assigned, the CMTS MUST assign the CM to the appropriate general load balancing group based on the new upstream channel, or to no load balancing group if the new upstream channel is not associated with a general load balancing group. Note that a CM provisioned into a restricted load balancing group will (unless the provisioning is changed) be returned to its provisioned group by the CMTS upon a re-initialize MAC operation. Thus, a manual DCC operation that moves a CM outside of its restricted load balancing group will generally be only a temporary move, until the CM re-initializes. Further, specifying initialization technique zero in the DCC request would result in the CM being returned immediately to its provisioned group.
+
+#### **11.4.5.6.2 Initialization techniques**
+
+The description of a load balancing group includes the initialization technique(s) that could be used when autonomously load balancing a cable modem within the group. The initialization technique definition for each load balancing group is represented in the form of a bit map, with each bit representing a specific technique (bits 0-4).
+
+The CMTS MUST support, via SNMP, the override of this initialization technique for channel changes between specific pairs of logical upstream channels. If an override is present for a particular pair of channels, the CMTS MUST use the initialization technique for the channel pair. Otherwise, the CMTS MUST use the default initialization technique definition for the load balancing group.
+
+#### **11.4.5.6.3 Load balancing policies**
+
+Load balancing policies allow control over the behaviour of the autonomous load balancing process on a per-CM basis. A load balancing policy is described by a set of conditions (rules) that govern the autonomous load balancing process for the CM. When a load balancing policy is defined by multiple rules, all of the rules apply in combination.
+
+Load balancing rules and the load balancing policy definition mechanism have been created to allow for specific vendor-defined load balancing actions. However, there are two basic rules that the CMTS is required to support.
+
+The CMTS MUST support the following basic rules:
+
+- Prohibit load balancing using a particular CM.
+- Prohibit load balancing using a particular CM during certain times of the day.
+
+The policy ID value of zero is reserved to indicate the CMTS's basic load balancing mechanism, which does not need to be defined by a set of rules.
+
+Each load balancing group has a default load balancing policy. During the registration process, the CMTS MUST assign the CM a load balancing policy ID. The policy ID may be assigned to a cable modem via the cable modem config file. The CMTS MUST assign the CM the load balancing
+
+policy ID provisioned in the config file and sent in the REG-REQ, if it exists. Otherwise, the CMTS MUST assign the CM the default policy ID defined for the load balancing group.
+
+The per-CM load balancing policy ID assignment can be modified at any time while the CM is in the operational state via SNMP or internal CMTS processes, however the policy ID is always overwritten upon receipt of a REG-REQ message.
+
+#### **11.4.5.6.4 Load balancing priorities**
+
+A load balancing priority is an index that defines a rank or level of importance, which is used to apply differential treatment between CMs in the CMTS's load balancing decision process.
+
+In general, a lower load balancing priority indicates a higher likelihood that a CM will be moved due to load balancing operations. The CMTS MAY take many factors into account when selecting a CM to move, of which priority is only one. When other factors are equal, the CMTS SHOULD preferentially move a CM with lower load balancing priority over one with higher load balancing priority.
+
+The CMTS MUST associate each cable modem with a load balancing priority. Priority may be assigned to a cable modem via the cable modem config file. The CMTS MUST assign the CM the load balancing priority provisioned in the config file and sent in the REG-REQ, if it exists. If a cable modem has not been assigned a priority, the cable modem is associated with the default (lowest) load balancing priority value of zero.
+
+The per-CM load balancing priority assignment can be modified at any time while the CM is in the operational state via SNMP or internal CMTS processes as dictated by a specific load balancing policy; however, the priority assignment is always overwritten upon receipt of a REG-REQ message.
+
+#### **11.4.5.6.5 Load balancing and multicast**
+
+The IGMP protocol requires hosts to suppress IGMP messages that are not necessary for the router to maintain multicast group membership state. Clause 5.3.1 extends these IGMP requirements to the DOCSIS access network by requiring CMs to suppress messages that are deemed to be superfluous for the CMTS. As a result, the CMTS is not guaranteed to be aware of multicast group membership on a per-CM basis. For an active multicast group, there could be any number of CMs that have group members and that are actively forwarding multicast traffic, but that have not sent a membership report to the CMTS. This lack of CMTS awareness can create a situation in which load balancing and multicast conflict.
+
+In order to efficiently manage multicast traffic and balance load across a load balancing group, it is reasonable to expect that the CMTS might attempt to reduce the amount of duplicated multicast traffic by consolidating all members for a specific multicast group to a single downstream channel in the load balancing group. More generally, a load balancing algorithm will perform more effectively if it takes into account both the unicast and multicast traffic load for each CM when making decisions on where and when to move CMs. This is made difficult when the CMTS is unaware of which CMs have multicast group members and which do not.
+
+If a CM with active multicast sessions is moved from its current downstream to a new downstream that is not carrying the multicast traffic, the session will be interrupted until the CM or CPE sends a membership report. In order to reduce the interruption of multicast service, CMs that implement active IGMP mode (see clause 5.3.1) SHOULD send a membership report for all active multicast groups upon completion of a DCC operation that involves a downstream channel change.
+
+The multicast issues are alleviated to some degree when BPI+ is enabled, and are alleviated further when multicast traffic is encrypted using dynamic security associations (see [DOCS8]).
+
+When BPI+ is enabled, a CM will, upon receiving an IGMP "join" message on its CPE interface, send a SA map request message to the CMTS. Since this message is only sent at the moment
+
+multicast group membership begins, it does not provide any indication of ongoing membership. Because multicast group membership can be transient, the past receipt of a map request for a particular multicast group, although necessary, is not a sufficient condition to alert the CMTS that the CM currently has members for that multicast group. The absence of a map request is sufficient evidence that the CM does not have members for the multicast group.
+
+If the multicast traffic for a particular multicast group is encrypted using a dynamic security association, the CMTS can monitor the reception of TEK key requests and gain knowledge of multicast group membership. Since it is optional functionality for a CM to stop the TEK state machine (and discontinue sending key requests) when there are no longer members for multicast groups mapped to a particular security association, the continued receipt of key requests by the CMTS does not necessarily indicate continued multicast group membership. The lack of continuing key requests, however, does indicate lack of members.
+
+#### 11.4.5.6.6 Examples demonstrating autonomous load balancing
+
+Figure 11-67 shows an example combining network which illustrates the definition of general load balancing groups and the use of restricted load balancing groups to resolve topological ambiguities.
+
+![Figure 11-67 – Example combining network 1. The diagram shows a CMTS on the left connected to four fibre nodes on the right. The CMTS contains a Downstream (DS) channel and six Upstream (US) channels (US0-US5). The DS channel is connected to a 4-way splitter (4w) which feeds all four fibre nodes. The US channels are connected to 2-way splitters (2w) which then connect to the fibre nodes. US0 connects to fibre node 1. US1 and US2 connect to fibre node 2. US3 and US4 connect to fibre node 3. US4 and US5 connect to fibre node 4. Each fibre node contains a High (H) and Low (L) band splitter. The diagram is labeled J.122(09)_F11-67.](2ffdb0621c4918479cd1ac7a531b1b92_img.jpg)
+
+Figure 11-67 – Example combining network 1. The diagram shows a CMTS on the left connected to four fibre nodes on the right. The CMTS contains a Downstream (DS) channel and six Upstream (US) channels (US0-US5). The DS channel is connected to a 4-way splitter (4w) which feeds all four fibre nodes. The US channels are connected to 2-way splitters (2w) which then connect to the fibre nodes. US0 connects to fibre node 1. US1 and US2 connect to fibre node 2. US3 and US4 connect to fibre node 3. US4 and US5 connect to fibre node 4. Each fibre node contains a High (H) and Low (L) band splitter. The diagram is labeled J.122(09)\_F11-67.
+
+**Figure 11-67 – Example combining network 1**
+
+In this example, there are six upstream channels (US0-US5) that are members of a single MAC domain. All six upstream channels are associated with a single downstream channel (DS). The downstream is split over all four fibre nodes, while the six upstreams return from the four nodes via the combining network shown, such that each upstream channel is not physically connected to each fibre node. In particular, fibre node 1 connects to US0 only, fibre node 2 connects to both US1 and US2, fibre node 3 connects to both US3 and US4, and fibre node 4 connects to both US4 and US5.
+
+In this situation, the load balancing groups could be defined as follows:
+
+Load balancing group 1:
+
+|                      |         |
+|----------------------|---------|
+| Group ID:            | 1       |
+| Type:                | General |
+| Downstream channels: | DS      |
+
+Upstream channels: US1, US2
+
+Load balancing group 2:
+
+Group ID: 2
+
+Type: Restricted
+
+Downstream channels: DS
+
+Upstream channels: US3, US4
+
+Load balancing group 3:
+
+Group ID: 3
+
+Type: Restricted
+
+Downstream channels: DS
+
+Upstream channels: US4, US5
+
+Note that a REG-REQ on either upstream channel US1 or US2 uniquely identifies the load balancing group to which a CM can be assigned, hence those two channels form the general load balancing group 1. Upstream channels US3-US5 have a more complex topology, since US4 is shared across two fibre nodes. To resolve the topological ambiguities that would arise by a REG-REQ received on US4, two restricted load balancing groups have been defined (Group IDs 2 and 3). In order to be load balanced, each CM that is attached to fibre node 3 would need to be provisioned to be a member of restricted load balancing group 2, while each CM attached to fibre node 4 would need to be provisioned into restricted load balancing group 3. If a CM were to register on one of these channels without having been provisioned into the appropriate restricted load balancing group, the CMTS would not associate the CM with any load balancing group (which results in the CM not being load balanced).
+
+Also, note that US0 is not a member of any load balancing group. CMs that register on that upstream channel will not be load balanced to another channel.
+
+Figure 11-68 shows a second example, in which two MAC domains are shared across two fibre nodes in a complex combining network. In this example, a pair of upstream channels (one from each MAC domain) are set aside for a particular customer group (e.g., business customers), a restricted load balancing group is formed to allow load balancing for those customers.
+
+![Diagram of an example combining network (Figure 11-68). On the left, a CMTS is shown with various channels: DS0, US00, US01, US02, US03, US13, US12, US11, US10, and DS1. These channels are connected to a series of optical components. US00 and US01 are connected to a 2-way splitter. US02 and US03 are connected to a 4-way splitter. US13 and US12 are connected to another 2-way splitter. US11 and US10 are connected to another 4-way splitter. The outputs of these splitters are connected to two fibre nodes, labeled 1 and 2. Each fibre node contains a high-power amplifier (H) and a low-power amplifier (L). The diagram also shows various optical components like isolators and couplers. A label 'J.122(09)_F11-68' is present in the bottom right corner of the diagram area.](bdef4f97fd2f24c6f723acd5d1cbd17c_img.jpg)
+
+Diagram of an example combining network (Figure 11-68). On the left, a CMTS is shown with various channels: DS0, US00, US01, US02, US03, US13, US12, US11, US10, and DS1. These channels are connected to a series of optical components. US00 and US01 are connected to a 2-way splitter. US02 and US03 are connected to a 4-way splitter. US13 and US12 are connected to another 2-way splitter. US11 and US10 are connected to another 4-way splitter. The outputs of these splitters are connected to two fibre nodes, labeled 1 and 2. Each fibre node contains a high-power amplifier (H) and a low-power amplifier (L). The diagram also shows various optical components like isolators and couplers. A label 'J.122(09)\_F11-68' is present in the bottom right corner of the diagram area.
+
+Figure 11-68 – Example combining network 2
+
+Load balancing group 1:
+
+Group ID: 1  
+ Type: General  
+ Downstream channels: DS0, DS1  
+ Upstream channels: US00, US01, US12  
+ Subgroup: DS0, US00, US01
+
+Load balancing group 2:
+
+Group ID: 2  
+ Type: General  
+ Downstream channels: DS0, DS1  
+ Upstream channels: US10, US11, US02  
+ Subgroup: DS1, US10, US11
+
+Load balancing group 3:
+
+Group ID: 3  
+ Type: Restricted  
+ Downstream channels: DS0, DS1  
+ Upstream channels: US03, US13
+
+## 11.5 Fault detection and recovery
+
+Fault detection and recovery occurs at multiple levels.
+
+- At the physical level, FEC is used to correct errors where possible – refer to clause 6 for details.
+- The MAC protocol protects against errors through the use of checksum fields across both the MAC header and the data portions of the packet – refer to clause 8 for details.
+- All MAC management messages are protected with a CRC covering the entire message, as defined in clause 8. Any message with a bad CRC MUST be discarded by the receiver.
+
+Table 11-2 shows the recovery process that MUST be taken following the loss of a specific type of MAC message.
+
+**Table 11-2 – Recovery process on loss of specific MAC messages**
+
+| Message name | Action following message loss                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
+|--------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| SYNC         | The CM can lose SYNC messages for a period of the lost SYNC interval (see Annex B) before it has lost synchronization with the network. A CM that has lost synchronization MUST NOT use the upstream and MUST try to re-establish synchronization.                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
+| UCD          | During CM initialization, the CM MUST receive a usable UCD <sup>a)</sup> before transmitting on the upstream. When in the "obtain upstream parameters" state of CM initialization process, if the CM does not receive a usable UCD within the T1 time-out period, the CM MUST NOT transmit on the upstream and MUST scan for another downstream channel. After receiving a usable UCD, whenever the CM receives an unusable UCD or a MAP with a UCD count that does not match the configuration change count of the last UCD received, the CM MUST NOT transmit on the upstream and MUST start the T1 timer. If the T1 timer expires under these circumstances, the CM MUST reset and re-initialize its MAC connection. |
+| MAP          | A CM MUST NOT transmit without a valid upstream bandwidth allocation. If a MAP                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
+
+**Table 11-2 – Recovery process on loss of specific MAC messages**
+
+| Message name       | Action following message loss                                                                                                                                                                                                                                                                                                                           |
+|--------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+|                    | is missed due to error, the CM MUST NOT transmit for the period covered by the MAP.                                                                                                                                                                                                                                                                     |
+| RNG-REQ<br>RNG-RSP | If a CM fails to receive a valid ranging response within a defined time-out period after transmitting a request, the request MUST be retried a number of times (as defined in Annex B). Failure to receive a valid ranging response after the requisite number of attempts MUST cause the modem to reset and reinitialize its MAC connection.           |
+| REG-REQ<br>REG-RSP | If a CM fails to receive a valid registration response within a defined time-out period after transmitting a request, the request will be retried a number of times (as defined in Annex B). Failure to receive a valid registration response after the requisite number of attempts will cause the modem to reset and reinitialize its MAC connection. |
+| UCC-REQ<br>UCC-RSP | If a CMTS fails to receive a valid upstream channel change response within a defined time-out period after transmitting a request, the request MUST be retried a number of times (as defined in Annex B). Failure to receive a valid response after the requisite number of attempts MUST cause the CMTS to consider the CM as unreachable.             |
+| <sup>a)</sup>      | A usable UCD is one that contains legal profiles that the modem can understand. The CM MAY also require that the UCD count of the MAPs received match the configuration change count field of the last received UCD before it considers the UCD as usable.                                                                                              |
+
+Annex D of [DOCS5] contains a list of error codes with more useful information as to the failure of the PHY and MAC layers. Refer to clause 8.2.8 for additional information.
+
+Messages at the network layer and above are considered to be data packets by the MAC sublayer. These are protected by the CRC field of the data packet and any packets with bad CRCs are discarded. Recovery from these lost packets is in accordance with the upper layer protocol.
+
+#### 11.5.1 Prevention of unauthorized transmissions
+
+A CM SHOULD include a means for terminating RF transmission if it detects that its own carrier has been on continuously for longer than the longest possible valid transmission.
+
+### 12 Supporting future new cable modem capabilities
+
+#### 12.1 Downloading cable modem operating software
+
+A CMTS SHOULD be capable of being remotely reprogrammed in the field via a software download over the network.
+
+The cable modem MUST be capable of being remotely reprogrammed in the field via a software download over the network. This software download capability MUST allow the functionality of the cable modem to be changed without requiring that cable system personnel physically revisit and reconfigure each unit. It is expected that this field programmability will be used to upgrade cable modem software to improve performance, accommodate new functions and features (such as enhanced class-of-service support), correct any design deficiencies discovered in the software, and to allow a migration path as the data-over-cable interface Recommendation evolves.
+
+The mechanism used for download MUST be TFTP file transfer. The mechanism by which transfers are secured and authenticated is in [DOCS8]. The transfer MUST be initiated in one of two ways:
+
+- An SNMP manager requests the CM to upgrade.
+
+- If the software upgrade file name in the CM's configuration file does not match the current software image of the CM, the CM MUST request the specified file via TFTP from the software server.
+
+NOTE – The software server IP address is a separate parameter. If present, the CM MUST attempt to download the specified file from this server. If not present, the CM MUST attempt to download the specified file from the configuration file server.
+
+The CM MUST verify that the downloaded image is appropriate for itself. If the image is appropriate, the CM MUST write the new software image to non-volatile storage. Once the file transfer is completed successfully, the CM MUST restart itself with the new code image.
+
+If the CM is unable to complete the file transfer for any reason, it MUST remain capable of accepting new software downloads (without operator or user interaction), even if power or connectivity is interrupted between attempts. The CM MUST log the failure and MAY report it asynchronously to the network manager.
+
+Following upgrade of the operational software, the CM MAY need to follow one of the procedures described above in order to change channels to use the enhanced functionality.
+
+If the CM is to continue to operate in the same upstream and downstream channels as before the upgrade, then it MUST be capable of interworking with other CMs that may be running previous software releases.
+
+Where software has been upgraded to meet a new version of the Recommendation, it is critical that it MUST interwork with the previous version in order to allow a gradual transition of units on the network.
+
+## Annex A
+
+### Well-known addresses
+
+(This annex forms an integral part of this Recommendation)
+
+#### A.1 MAC addresses
+
+MAC addresses described here are defined using the Ethernet/ISO/IEC 8802-3 convention as bit-little-endian.
+
+The following multicast address MUST be used to address the set of all CM MAC sublayers; for example, when transmitting allocation map PDUs:
+
+01-E0-2F-00-00-01
+
+The addresses in the range
+
+01-E0-2F-00-00-02 through 01-E0-2F-00-00-0F
+
+are reserved for future definition. Frames addressed to any of these addresses SHOULD NOT be forwarded out of the MAC-sublayer domain.
+
+#### A.2 MAC service IDs
+
+The following MAC service IDs have assigned meanings. Those not included in this table are available for assignment, either by the CMTS or administratively.
+
+##### A.2.1 All CMs and no CM service IDs
+
+The following service IDs are used in MAPs for special purposes or to indicate that any CM can respond in the corresponding interval.
+
+0x0000 is addressed to no CM. This address is typically used when changing upstream burst parameters so that CMs have time to adjust their modulators before the new upstream settings take effect. This is also the "initialization SID" used by the CM during initial ranging.
+
+0x3FFF is addressed to all CMs. It is typically used for broadcast request intervals or initial maintenance intervals.
+
+##### A.2.2 Well-known multicast service IDs
+
+The following service IDs are only used for request/data IEs. They indicate that any CM can respond in a given interval, but that the CM must limit the size of its transmission to a particular number of mini-slots (as indicated by the particular multicast SID assigned to the interval).
+
+0x3FF1-0x3FFE is addressed to all CMs. IDs in this range are available for small data PDUs as well as requests (used only with request/data IEs). The last digit indicates the frame length and transmission opportunities as follows:
+
+- 0x3FF1: Within the interval specified, a transmission may start at any mini-slot, and must fit within one mini-slot.
+- 0x3FF2: Within the interval specified, a transmission may start at every other mini-slot, and must fit within two mini-slots (e.g., a station may start transmission on the first mini-slot within the interval, the third mini-slot, the fifth, etc.).
+- 0x3FF3: Within the interval specified, a transmission may start at any third mini-slot, and must fit within three mini-slots (e.g., starts at first, fourth, seventh, etc.).
+- 0x3FF4: Starts at first, fifth, ninth, etc.
+- 0x3FFD: Starts at first, fourteenth (14th), twenty-seventh (27th), etc.
+
+- 0x3FFE: Within the interval specified, a transmission may start at any 14th mini-slot, and must fit within 14 mini-slots.
+
+### **A.2.3 Priority request service IDs**
+
+The following service IDs (0x3Exx) are reserved for request IEs (refer to clause C.2.2.5.1, "traffic priority").
+
+- If 0x01 bit is set, priority zero can request.
+- If 0x02 bit is set, priority one can request.
+- If 0x04 bit is set, priority two can request.
+- If 0x08 bit is set, priority three can request.
+- If 0x10 bit is set, priority four can request.
+- If 0x20 bit is set, priority five can request.
+- If 0x40 bit is set, priority six can request.
+- If 0x80 bit is set, priority seven can request.
+
+Bits can be combined as desired by the CMTS upstream scheduler for any request IUCs.
+
+### **A.3 MPEG PID**
+
+All DOCS data MUST be carried in MPEG-2 packets with the header PID field set to 0x1FFE.
+
+## Annex B
+
+### Parameters and constants
+
+(This annex forms an integral part of this Recommendation)
+
+| System     | Name                                   | Time reference                                                                                                                     | Minimum value                           | Default value | Maximum value        |
+|------------|----------------------------------------|------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------|---------------|----------------------|
+| CMTS       | Sync interval                          | Nominal time between transmission of SYNC messages (see clause 8.3.2)                                                              |                                         |               | 200 ms               |
+| CMTS       | UCD interval                           | Time between transmission of UCD messages (see clause 8.3.3, "upstream channel descriptor (UCD)")                                  |                                         |               | 2 s                  |
+| CMTS       | Max MAP pending                        | The number of mini-slots that a CMTS is allowed to map into the future (see clause 8.3.4)                                          |                                         |               | 4096 mini-slot times |
+| CMTS       | Ranging interval                       | Time between transmission of broadcast ranging requests (see clause 9.3.3)                                                         |                                         |               | 2 s                  |
+| CM         | Lost sync interval                     | Time since last received sync message before synchronization is considered lost                                                    |                                         |               | 600 ms               |
+| CM         | Contention ranging retries             | Number of retries on contention ranging requests (see clause 11.2.4)                                                               |                                         | 16            |                      |
+| CM<br>CMTS | Invited ranging retries                | Number of retries on inviting ranging requests (see clause 11.2.4)                                                                 |                                         | 16            |                      |
+| CM         | Request retries                        | Number of retries on bandwidth allocation requests                                                                                 |                                         | 16            |                      |
+| CM<br>CMTS | Registration request/ response retries | Number of retries on registration requests/responses                                                                               |                                         | 3             |                      |
+| CM         | Data retries                           | Number of retries on immediate data transmission                                                                                   |                                         | 16            |                      |
+| CMTS       | CM MAP processing time                 | Time provided between arrival of the last bit of a MAP at a CM and effectiveness of that MAP (see clause 9.1.5)                    | $(200 + M/5.12)$ μs (see clause 6.2.17) |               |                      |
+| CMTS       | CM ranging response processing time    | Minimum time allowed for a CM following receipt of a ranging response before it is expected to reply to an invited ranging request | 1 ms                                    |               |                      |
+| CMTS       | CM configuration                       | The maximum time allowed for a CM, following receipt of a configuration file, to send a registration request to a CMTS             | 30 s                                    |               |                      |
+
+| System     | Name                                      | Time reference                                                                                                                                                       | Minimum value           | Default value | Maximum value                  |
+|------------|-------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------|---------------|--------------------------------|
+| CM         | T1                                        | Wait for UCD time-out                                                                                                                                                |                         |               | 5 × UCD interval maximum value |
+| CM         | T2                                        | Wait for broadcast ranging time-out                                                                                                                                  |                         |               | 5 × ranging interval           |
+| CM         | T3                                        | Wait for ranging response                                                                                                                                            | 50 ms                   | 200 ms        | 200 ms                         |
+| CM         | T4                                        | Wait for unicast ranging opportunity. If the pending-till-complete field was used earlier by this modem, then the value of that field must be added to this interval | 30 s                    |               | 35 s                           |
+| CMTS       | T5                                        | Wait for upstream channel change response                                                                                                                            |                         |               | 2 s                            |
+| CM<br>CMTS | T6                                        | Wait for REG-RSP and REG-ACK                                                                                                                                         |                         |               | 3 s                            |
+| CM<br>CMTS | Mini-slot size for 1.x channels           | Size of mini-slot for upstream transmission. For channels that support DOCS 1.x CMs                                                                                  | 32 modulation intervals |               |                                |
+| CM<br>CMTS | Mini-slot size for DOCS 2.0 Only Channels | Size of mini-slot for upstream transmission. For channels that do not support DOCS 1.x CMs                                                                           | 16 symbols              |               |                                |
+| CM<br>CMTS | Timebase tick                             | System timing unit                                                                                                                                                   | 6.25 µs                 |               |                                |
+| CM<br>CMTS | DSx request retries                       | Number of time-out retries on DSA/DSC/DSD requests                                                                                                                   | 3                       |               |                                |
+| CM<br>CMTS | DSx response retries                      | Number of timeout retries on DSA/DSC/DSD responses                                                                                                                   | 3                       |               |                                |
+| CM<br>CMTS | T7                                        | Wait for DSA/DSC/DSD response timeout                                                                                                                                |                         |               | 1 s                            |
+| CM<br>CMTS | T8                                        | Wait for DSA/DSC acknowledge timeout                                                                                                                                 |                         |               | 300 ms                         |
+| CM         | TFTP backoff start                        | Initial value for TFTP backoff                                                                                                                                       | 1 s                     |               |                                |
+| CM         | TFTP backoff end                          | Last value for TFTP backoff                                                                                                                                          | 16 s                    |               |                                |
+| CM         | TFTP request retries                      | Number of retries on TFTP request                                                                                                                                    | 16                      |               |                                |
+| CM         | TFTP download retries                     | Number of retries on entire TFTP downloads                                                                                                                           | 3                       |               |                                |
+| CM         | TFTP wait                                 | The wait between TFTP retry sequences                                                                                                                                | 10 min                  |               |                                |
+| CM         | ToD retries                               | Number of retries per ToD retry period                                                                                                                               | 3                       |               |                                |
+| CM         | ToD retry period                          | Time period for ToD retries                                                                                                                                          | 5 min                   |               |                                |
+
+| System     | Name                   | Time reference                                                                                                                                                                    | Minimum value | Default value | Maximum value |
+|------------|------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|---------------|
+| CMTS       | T9                     | Registration timeout, the time allowed between the CMTS sending a RNG-RSP (success) to a CM, and receiving a REG-REQ from that same CM                                            | 15 min        | 15 min        |               |
+| CM<br>CMTS | T10                    | Wait for transaction end timeout                                                                                                                                                  |               |               | 3 s           |
+| CMTS       | T11                    | Wait for a DCC response on the old channel                                                                                                                                        |               |               | 300 ms        |
+| CM         | T12                    | Wait for a DCC acknowledge                                                                                                                                                        |               |               | 300 ms        |
+| CMTS       | T13                    | Maximum holding time for QoS resources for DCC on the old channel                                                                                                                 |               |               | 1 s           |
+| CM         | T14                    | Minimum time after a DSx reject-temp-DCC and the next retry of DSx command                                                                                                        | 2 s           |               |               |
+| CMTS       | T15                    | Maximum holding time for QoS resources for DCC on the new channel                                                                                                                 | 2 s           |               | 35 s          |
+| CM         | T16                    | Maximum length of time CM remains in test mode after receiving TST-REQ message                                                                                                    |               |               | 30 min        |
+| CM         | T17                    | Maximum time that CM MUST inhibit transmissions on a channel in response to its ranging class ID matching a bit value in the ranging hold-off priority field                      |               |               | 300 s         |
+| CMTS       | DCC-REQ retries        | Number of retries on dynamic channel change request                                                                                                                               | 3             |               |               |
+| CM         | DCC-RSP retries        | Number of retries on dynamic channel change response                                                                                                                              | 3             |               |               |
+| CM         | Lost DCI-REQ interval  | Time from sending DCI-REQ and not receiving a DCI-RSP                                                                                                                             |               |               | 2 s           |
+| CM         | DCI-REQ retry          | Number of retries of DCI-REQ before rebooting                                                                                                                                     |               |               | 16            |
+| CM         | DCI backoff start      | Initial value for DCI backoff                                                                                                                                                     | 1 s           |               |               |
+| CM         | DCI backoff end        | Last value for DCI backoff                                                                                                                                                        | 16 s          |               |               |
+| CMTS       | CM UCD processing time | Time between the transmission of the last bit of a UCD with a new change count and the transmission time of the first bit of the first MAP using the new UCD (see clause 11.3.2). | 1 ms          |               |               |
+
+## Annex C
+
+### Common radio frequency interface encodings
+
+(This annex forms an integral part of this Recommendation)
+
+#### C.1 Encodings for configuration and MAC-layer messaging
+
+The following type/length/value encodings MUST be used in both the configuration file (see Annex D), in CM registration requests and in dynamic service messages. All multi-octet quantities are in network-byte order, i.e., the octet containing the most-significant bits is the first transmitted on the wire.
+
+The following configuration settings MUST be supported by all CMs which are compliant with this Recommendation.
+
+##### C.1.1 Configuration file and registration settings
+
+These settings are found in the configuration file and, if present, MUST be forwarded by the CM to the CMTS in its registration request.
+
+###### C.1.1.1 Downstream frequency configuration setting
+
+The receive frequency to be used by the CM unless a downstream channel list is present. It is an override for the channel selected during scanning. This is the centre frequency of the downstream channel in Hz stored as a 32-bit binary number.
+
+| Type | Length | Value        |
+|------|--------|--------------|
+| 1    | 4      | Rx frequency |
+
+Valid range: The receive frequency MUST be a multiple of 62'500 Hz.
+
+###### C.1.1.2 Upstream channel ID configuration setting
+
+The Upstream Channel ID that the CM MUST use. The CM MUST listen on the defined downstream channel until an upstream channel description message with this ID is found. It is an override for the channel selected during initialization.
+
+| Type | Length | Value      |
+|------|--------|------------|
+| 2    | 1      | Channel ID |
+
+###### C.1.1.3 Network access control object
+
+If the value field is a 1, CPEs attached to this CM are allowed access to the network, based on CM provisioning. If the value of this field is a 0, the CM MUST NOT forward traffic from attached CPE to the RF MAC network, but MUST continue to accept and generate traffic from the CM itself. The value of this field does not affect CMTS service flow operation and does not affect CMTS data forwarding operation.
+
+| Type | Length | On/off |
+|------|--------|--------|
+| 3    | 1      | 1 or 0 |
+
+The intent of "NACO = 0" is that the CM does not forward traffic from any attached CPE onto the cable network (a CPE is any client device attached to that CM, regardless of how that attachment is implemented). However, with "NACO = 0", management traffic to the CM is not restricted. Specifically, with NACO off, the CM remains manageable, including sending/receiving management traffic such as (but not limited to):
+
+- ARP: Allow the modem to resolve IP addresses, so it can respond to queries or send traps.
+- DHCP: Allow the modem to renew its IP address lease.
+- ICMP: Enable network troubleshooting for tools such as "ping" and "traceroute."
+- ToD: Allow the modem to continue to synchronize its clock after boot.
+- TFTP: Allow the modem to download either a new configuration file or a new software image.
+- SYSLOG: Allow the modem to report network events.
+- SNMP: Allow management activity
+
+In DOCS v1.1, with NACO off, the primary upstream and primary downstream service flows of the CM remain operational only for management traffic to and from the CM. With respect to DOCS v1.1 provisioning, a CMTS should ignore the NACO value and allocate any service flows that have been authorized by the provisioning server.
+
+#### C.1.1.4 DOCS 1.0 class-of-service configuration setting
+
+This field defines the parameters associated with a DOCS 1.0 class of service. Any CM registering with a DOCS 1.0 class-of-service configuration setting MUST be treated as a DOCS 1.0 CM. Refer to clause 8.3.8, "registration response (REG-RSP)".
+
+This field defines the parameters associated with a class of service. It is somewhat complex in that it is composed from a number of encapsulated type/length/value fields. The encapsulated fields define the particular class-of-service parameters for the class of service in question. Note that the type fields defined are only valid within the encapsulated class-of-service configuration setting string. A single class-of-service configuration setting is used to define the parameters for a single service class. Multiple class definitions use multiple class-of-service configuration setting sets.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 4    | n      |       |
+
+##### C.1.1.4.1 Class ID
+
+The value of the field specifies the identifier for the Class of Service to which the encapsulated string applies.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 4.1  | 1      |       |
+
+Valid range: The class ID MUST be in the range 1 to 16.
+
+##### C.1.1.4.2 Maximum downstream rate configuration setting
+
+For a single-SID modem, the value of this field specifies the maximum downstream rate in bits per second that the CMTS is permitted to forward to CPE unicast MAC addresses learned or configured as mapping to the registering modem.
+
+For a multiple-SID modem, the aggregate value of these fields specifies the maximum downstream rate in bits per second that the CMTS is permitted to forward to CPE unicast MAC addresses learned or configured as mapping to the registering modem.
+
+This is the peak data rate for packet PDU data (including destination MAC address and the CRC) over a one-second interval. This does not include MAC packets addressed to broadcast or multicast MAC addresses. The CMTS MUST limit downstream forwarding to this rate. The CMTS MAY delay, rather than drop, over-limit packets.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 4.2  | 4      |       |
+
+NOTE – This is a limit, not a guarantee that this rate is available.
+
+#### C.1.1.4.3 Maximum upstream rate configuration setting
+
+The value of this field specifies the maximum upstream rate in bits per second that the CM is permitted to forward to the RF network.
+
+This is the peak data rate for packet PDU data (including destination address and the CRC) over a one-second interval. The CM MUST limit all upstream forwarding (both contention and reservation-based), for the corresponding SID, to this rate. The CM MUST include packet PDU data packets addressed to broadcast or multicast addresses when calculating this rate.
+
+The CM MUST enforce the maximum upstream rate. It SHOULD NOT discard upstream traffic simply because it exceeds this rate.
+
+The CMTS MUST enforce this limit on all upstream data transmissions, including data sent in contention. The CMTS SHOULD generate an alarm if a modem exceeds its allowable rate.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 4.3  | 4      |       |
+
+NOTE 1 – The purpose of this parameter is for the CM to perform traffic shaping at the input to the RF network and for the CMTS to perform traffic policing to ensure that the CM does not exceed this limit.
+
+The CMTS could enforce this limit by any of the following methods:
+
+- discarding over-limit requests;
+- deferring (through zero-length grants) the grant until it is conforming to the allowed limit;
+- discarding over-limit data packets;
+- reporting to a policy monitor (for example, using the alarm mechanism) that is capable of incapacitating errant CMs.
+
+NOTE 2 – This is a limit, not a guarantee that this rate is available.
+
+#### C.1.1.4.4 Upstream channel priority configuration setting
+
+The value of the field specifies the relative priority assigned to this service class for data transmission in the upstream channel. Higher numbers indicate higher priority.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 4.4  | 1      |       |
+
+Valid range: 0-7.
+
+#### C.1.1.4.5 Guaranteed minimum upstream channel data rate configuration setting
+
+The value of the field specifies the data rate in bit/s which will be guaranteed to this service class on the upstream channel.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 4.5  | 4      |       |
+
+#### C.1.1.4.6 Maximum upstream channel transmit burst configuration setting
+
+The value of the field specifies the maximum transmit burst (in bytes) that this service class is allowed on the upstream channel. A value of zero means there is no limit.
+
+NOTE – This value does not include any physical layer overhead.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 4.6  | 2      |       |
+
+#### C.1.1.4.7 Class-of-service privacy enable
+
+This configuration setting enables/disables baseline privacy on a provisioned CoS.
+
+| Type                  | Length | Enable/Disable |
+|-----------------------|--------|----------------|
+| 4.7 (= CoS_BP_ENABLE) | 1      | 1 or 0         |
+
+**Table C.1 – Sample DOCS 1.0 class-of-service encoding**
+
+| Type | Length | Value (sub)type | Length | Value      |                                                           |
+|------|--------|-----------------|--------|------------|-----------------------------------------------------------|
+| 4    | 28     | 1               | 1      | 1          | Class-of-service configuration setting<br>Service class   |
+|      |        | 2               | 4      | 10'000'000 | Max. downstream rate of 10 Mbit/s                         |
+|      |        | 3               | 4      | 300'000    | Max. upstream rate of 300 kbit/s                          |
+|      |        | 4               | 1      | 5          | Return path priority of 5                                 |
+|      |        | 5               | 4      | 64'000     | Min. guaranteed 64 kbit/s                                 |
+|      |        | 6               | 2      | 1518       | Max. Tx burst of 1518 bytes                               |
+|      |        |                 |        |            |                                                           |
+| 4    | 28     | 1               | 1      | 2          | Class-of-service configuration setting<br>Service class 2 |
+|      |        | 2               | 4      | 5'000'000  | Max. forward rate of 5 Mbit/s                             |
+|      |        | 3               | 4      | 300'000    | Max. return rate of 300 Mbit/s                            |
+|      |        | 4               | 1      | 3          | Return path priority of 3                                 |
+|      |        | 5               | 4      | 32'000     | Min. guaranteed 32 kbit/s                                 |
+|      |        | 6               | 2      | 1518       | Max. Tx burst of 1518 bytes                               |
+|      |        |                 |        |            |                                                           |
+
+#### C.1.1.5 CM message integrity check (MIC) configuration setting
+
+The value field contains the CM message integrity check code. This is used to detect unauthorized modification or corruption of the configuration file.
+
+| Type | Length | Value          |
+|------|--------|----------------|
+| 6    | 16     | d1, d2,... d16 |
+
+#### C.1.1.6 CMTS message integrity check (MIC) configuration setting
+
+The value field contains the CMTS message integrity check code. This is used to detect unauthorized modification or corruption of the configuration file.
+
+| Type | Length | Value           |
+|------|--------|-----------------|
+| 7    | 16     | d1, d2, ... d16 |
+
+#### C.1.1.7 Maximum number of CPEs
+
+The maximum number of CPEs that can be granted access through a CM during a CM epoch. The CM epoch is (from clause 5.1.2.3.1) the time between start-up and hard reset of the modem. The maximum number of CPEs MUST be enforced by the CM.
+
+NOTE 1 – This parameter should not be confused with the number of CPE addresses a CM may learn. A modem may learn Ethernet MAC addresses up to its maximum number of CPE addresses (from clause 5.1.2.3.1). The maximum number of CPEs that are granted access through the modem is governed by this configuration setting.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 18   | 1      |       |
+
+The CM MUST interpret this value as an unsigned integer. The non-existence of this option, or the value 0, MUST be interpreted as the default value of 1.
+
+NOTE 2 – This is a limit on the maximum number of CPEs a CM will grant access to. Hardware limitations of a given modem implementation may require the modem to use a lower value.
+
+#### C.1.1.8 TFTP server timestamp
+
+The sending time of the configuration file in seconds. The definition of time is as in [RFC 868].
+
+| Type | Length | Value                                    |
+|------|--------|------------------------------------------|
+| 19   | 4      | Number of seconds since 00:00 1 Jan 1900 |
+
+NOTE – The purpose of this parameter is to prevent replay attacks with old configuration files.
+
+#### C.1.1.9 TFTP server provisioned modem address
+
+The IP address of the modem requesting the configuration file.
+
+| Type | Length | Value      |
+|------|--------|------------|
+| 20   | 4      | IP address |
+
+NOTE – The purpose of this parameter is to prevent IP spoofing during registration.
+
+#### C.1.1.10 Upstream packet classification configuration setting
+
+This field defines the parameters associated with one entry in an upstream traffic classification list. Refer to clause C.2.1.1.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 22   | n      |       |
+
+#### C.1.1.11 Downstream packet classification configuration setting
+
+This field defines the parameters associated with one classifier in a downstream traffic classification list. Refer to clause C.2.1.2.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 23   | n      |       |
+
+#### C.1.1.12 Upstream service flow encodings
+
+This field defines the parameters associated with upstream scheduling for one service flow. Refer to clause C.2.2.1.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 24   | n      |       |
+
+#### C.1.1.13 Downstream service flow encodings
+
+This field defines the parameters associated with downstream scheduling for one service flow. Refer to clause C.2.2.2.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 25   | n      |       |
+
+#### C.1.1.14 Payload header suppression
+
+This field defines the parameters associated with payload header suppression.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 26   | n      |       |
+
+#### C.1.1.15 Maximum number of classifiers
+
+This is the maximum number of classifiers associated with admitted or active upstream service flows that the CM is allowed to have. Both active and inactive classifiers are included in the count.
+
+This is useful when using deferred activation of provisioned resources. The number of provisioned service flows may be high and each service flow might support multiple classifiers. Provisioning represents the set of service flows the CM can choose between. The CMTS can control the QoS resources committed to the CM by limiting the number of service flows that are admitted. However, it may still be desirable to limit the number of classifiers associated with the committed QoS resources. This parameter provides that limit.
+
+| Type | Length | Value                                                                                                       |
+|------|--------|-------------------------------------------------------------------------------------------------------------|
+| 28   | 2      | Maximum number of active and inactive classifiers associated with admitted or active upstream service flows |
+
+The default value MUST be 0: No limit.
+
+#### C.1.1.16 Privacy enable
+
+This configuration setting enables/disables baseline privacy [DOCS8] on the primary service flow and all other service flows for this CM. If a DOCS 2.0 CM receives this setting in a configuration file, the CM is required to forward this setting as part of the registration request (REG-REQ) as specified in clause 8.3.7, regardless of whether the configuration file is DOCS 1.1-style or not, while this setting is usually contained only in a DOCS 1.1-style configuration file with DOCS 1.1 service flow TLVs.
+
+| Type | Length | Value                   |
+|------|--------|-------------------------|
+| 29   | 1      | 0: Disable<br>1: Enable |
+
+The default value of this parameter MUST be 1: privacy enabled.
+
+#### C.1.1.17 DOCSIS extension field
+
+The DOCSIS extension field is used to extend the capabilities of the DOCSIS specification, through the use of new and/or vendor-specific features.
+
+The DOCSIS extension field MUST be encoded using TLV 43 and MUST include the vendor ID field (refer to clause C.1.3.2) to indicate whether the DOCSIS extension field applies to all devices, or only to devices from a specific vendor. The vendor ID MUST be the first TLV embedded inside the DOCSIS extension field. If the first TLV inside the DOCSIS extension field is not a vendor ID, then the TLV MUST be discarded. In this context, the vendor ID of 0xFFFFF is reserved to signal that this DOCSIS extension field contains general extension information (see clause C.1.1.17.1), otherwise the DOCSIS extension field contains vendor-specific information (see clause C.1.1.17.2).
+
+This configuration setting MAY appear multiple times. This configuration setting MAY be nested inside a packet classification configuration setting, a service flow configuration setting, or a service flow response. The same vendor ID MAY appear multiple times. However, there MUST NOT be more than one vendor ID TLV inside a single TLV 43.
+
+The CM MUST ignore any DOCSIS extension field that it cannot interpret, but MUST still include the TLV in the REG-REQ message. The CM MUST NOT initiate the DOCSIS extension field TLVs.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 43   | n      |       |
+
+##### C.1.1.17.1 General extension information
+
+When using the DOCSIS extension field (TLV 43) to encode general extension information, the vendor ID of 0xFFFFF MUST be used as the first sub-TLV inside TLV 43.
+
+| Type | Length | Value                                                    |
+|------|--------|----------------------------------------------------------|
+| 43   | n      | 8, 3, 0xFFFFF, followed by general extension information |
+
+The following sub-TLVs are defined only as part of the general extension information. The type values may be re-defined for any purpose as part of a vendor-specific information encoding.
+
+###### C.1.1.17.1.1 CM load balancing policy ID
+
+The CMTS load balancing algorithm uses this config file setting as the CM load balancing policy ID. If present, this value overrides the default group policy assigned by the CMTS (see clause 11.4.5.6). This configuration setting should only appear once in a configuration file. This configuration setting MUST only be used in configuration files and REG-REQ messages, and MUST NOT be nested inside a packet classification configuration setting, a service flow configuration setting, or a service flow response.
+
+| Type | Length | Value     |
+|------|--------|-----------|
+| 43.1 | 4      | Policy ID |
+
+#### C.1.1.17.1.2 CM load balancing priority
+
+This config file setting is the CM load balancing priority to be used by the CMTS load balancing algorithm. If present, this value overrides the default priority assigned by the CMTS (see clause 11.4.5.6). This configuration setting should only appear once in a configuration file. This configuration setting MUST only be used in configuration files and REG-REQ messages, and MUST NOT be nested inside a packet classification configuration setting, a service flow configuration setting, or a service flow response.
+
+| Type | Length | Value    |
+|------|--------|----------|
+| 43.2 | 4      | Priority |
+
+#### C.1.1.17.1.3 CM load balancing group ID
+
+This config file setting is the restricted load balancing group ID defined at the CMTS. If present, this value overrides the general load balancing group. If no restricted load balancing group is defined that matches this group ID, the value is ignored by the CMTS (see clause 11.4.5.6). This configuration setting should only appear once in a configuration file. This configuration setting MUST only be used in configuration files and REG-REQ messages, and MUST NOT be nested inside a packet classification configuration setting, a service flow configuration setting, or a service flow response.
+
+| Type | Length | Value    |
+|------|--------|----------|
+| 43.3 | 4      | Group ID |
+
+#### C.1.1.17.1.4 CM ranging class ID extension
+
+This config file setting is the CM ranging class ID extension to be defined by the MSO. These bits will be prepended to the CM's default ranging class ID as the most significant bits of the 32-bit ranging class ID value. These bits will be sent in the REG-REQ as part of the CM's ranging class ID in the modem capabilities field. If the TLV is not included in the configuration file, the CM will use zero for this value. These bits allow the user to define special device classes that could be used to give those devices, or service types, preferential treatment with respect to ranging after a massive outage. After successful registration, the CM MUST store the entire 32-bit value in a non-volatile memory and use it for ranging decisions after a reboot or a re-init MAC event.
+
+| Type | Length | Value       |
+|------|--------|-------------|
+| 43.4 | 2      | Extended ID |
+
+#### C.1.1.17.1.5 L2VPN encoding
+
+The L2VPN encoding parameter is a multi-part encoding that configures how the CMTS performs layer 2 virtual private network bridging for CPE packets. The subtypes of the L2VPN encoding are specified in [L2VPN]. The CMTS MAY support the DOCSIS Layer 2 Virtual Private Network feature as defined in [L2VPN]. If the L2VPN feature is not supported, the CMTS MUST ignore the information in the L2VPN configuration setting.
+
+GEI-Encapsulated L2VPN encoding:
+
+| Type | Length | Value                                      |
+|------|--------|--------------------------------------------|
+| 43.5 | n      | L2VPN encoding subtype/length/value tuples |
+
+### C.1.1.17.2 Vendor-specific information
+
+Vendor-specific configuration information, if present, is encoded in the DOCSIS extension field (code 43) using the vendor ID field (refer to clause C.1.3.2) to specify which TLV tuples apply to which vendor's products.
+
+| Type | Length | Value                 |
+|------|--------|-----------------------|
+| 43   | n      | Per vendor definition |
+
+Example:
+
+Configuration with vendor A specific fields and vendor B specific fields:
+
+VSIF (43) + n (number of bytes inside this VSIF)  
+8 (vendor ID type) + 3 (length field) + vendor ID of vendor A  
+Vendor A – specific type #1 + length of the field + value #1  
+Vendor A – specific type #2 + length of the field + value #2  
+VSIF (43) + m (number of bytes inside this VSIF)  
+8 (vendor ID type) + 3 (length field) + vendor ID of vendor B  
+Vendor B – specific type + length of the field + value
+
+### C.1.1.18 Subscriber management TLVs
+
+The information in these TLVs is not used by the CM; rather, the information is used by the CMTS to populate the subscriber management MIB for this CM.
+
+If present in the configuration file, the CM MUST include these TLVs in the subsequent REG-REQ to be used by the CMTS to populate the subscriber management MIB for this CM. If present in the configuration file, the CM MUST include these TLVs in the CMTS MIC.
+
+#### C.1.1.18.1 Subscriber management control
+
+This three-byte field provides control information to the CMTS for the subscriber management MIB. The first two bytes represent the number of IP addresses permitted behind the CM. The third byte is used for control fields.
+
+| Type | Length | Value                                                                                                                                                                                                        |
+|------|--------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 35   | 3      | Byte 1, 2: docsSubMgtCpeControlMaxCpeIP (low-order 10 bits)<br>Byte 3, bit 0: docsSubMgtCpeControlActive<br>Byte 3, bit 1: docsSubMgtCpeControlLearnable<br>Byte 3, bits #2-7: reserved, must be set to zero |
+
+#### C.1.1.18.2 Subscriber management CPE IP table
+
+This field lists the IP addresses used to populate docsSubMgtCpeIpTable in the subscriber management MIB at the CMTS.
+
+| Type | Length            | Value                  |
+|------|-------------------|------------------------|
+| 36   | N (multiple of 4) | Ipa1, Ipa2, Ipa3, Ipa4 |
+
+### C.1.1.18.3 Subscriber management filter groups
+
+The subscriber management MIB allows an upstream and downstream filter group to be assigned to a CM and its associated CPEs and one or more embedded service/application functional entities (eSAFEs). These filter groups are encoded in the configuration file in a single TLV as follows:
+
+| Type | Length                   | Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
+|------|--------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 37   | N (multiples of 4 bytes) | Bytes 1, 2: docsSubMgtSubFilterDownstream group<br>Bytes 3, 4: docsSubMgtSubFilterUpstream group<br>Bytes 5, 6: docsSubMgtCmFilterDownstream group<br>Bytes 7, 8: docsSubMgtCmFilterUpstream group<br>Bytes 9, 10: docsSubMgtPsFilterDownstream group<br>Bytes 11, 12: docsSubMgtPsFilterUpstream group<br>Bytes 13, 14: docsSubMgtMtaFilterDownstream group<br>Bytes 15, 16: docsSubMgtMtaFilterUpstream group<br>Bytes 17, 18: docsSubMgtStbFilterDownstream group<br>Bytes 19, 20: docsSubMgtStbFilterUpstream group |
+
+### C.1.1.19 Enable 2.0 mode
+
+This configuration setting enables/disables DOCS 2.0 mode for a CM registering with a DOCS 2.0 CMTS.
+
+The default value of this parameter MUST be 1: 2.0 mode enabled.
+
+| Type | Length | Value                   |
+|------|--------|-------------------------|
+| 39   | 1      | 0: Disable<br>1: Enable |
+
+### C.1.1.20 Enable test modes
+
+This configuration setting enables/disables certain test modes for a CM which supports test modes. The definition of the test modes is beyond the scope of this Recommendation.
+
+If this TLV is not present, the default value MUST be 0: Test modes disabled.
+
+| Type | Length | Value                   |
+|------|--------|-------------------------|
+| 40   | 1      | 0: Disable<br>1: Enable |
+
+### C.1.1.21 Downstream channel list
+
+A list of receive frequencies to which the CM is allowed to tune during scanning operations. When the downstream channel list is provided in a configuration file, the CM MUST NOT attempt to establish communications using a downstream channel that is absent from this list unless specifically directed to do so by the CMTS. When both the downstream channel list and the downstream frequency configuration setting (clause C.1.1.1) are included in the configuration file, the CM MUST ignore the downstream frequency configuration setting. This list can override the last operational channel stored in NVRAM as defined in clause 11.2.1. The CM MUST retain and employ this list of channels whenever the CM performs a re-initialize MAC or continue scanning operation. The CM MUST replace or remove the list by subsequent config file downloads. Upon
+
+power cycle, the CM MUST NOT enforce a previously learned downstream channel list. The CM MAY, however, remember this list as an aid to downstream channel acquisition.
+
+| Type | Length | Value                          |
+|------|--------|--------------------------------|
+| 41   | n      | List of allowed Rx frequencies |
+
+The list of allowed downstream frequencies is composed of an ordered series of sub-TLVs (single downstream channel, downstream frequency range, and default scanning) as defined below. When scanning for a downstream channel (except after a power-cycle), the CM MUST scan through this ordered list and attempt to establish communications on the specified channel(s). The scanning is initialized as follows:
+
+- If the CM is in an operational state, and then undergoes a re-initialize MAC operation (except due to a dynamic channel change), it MUST first scan the last operational frequency and then restart scanning at the beginning of the ordered list.
+- If, while scanning this ordered list, the CM fails to become operational and is forced to re-initialize MAC, the CM MUST continue scanning from the next applicable frequency in the ordered list.
+- If it reaches the default scanning TLV (TLV 41.3) in the config file, the CM begins its default scanning algorithm, completing initial ranging and DHCP and receiving a new config file via TFTP on the first valid frequency it sees. If the new config file does not contain TLV 41, the CM MUST continue with registration. If the new config file contains TLV 41, the CM MUST confirm that the current downstream frequency is explicitly listed in the downstream channel list. If the current downstream channel is not explicitly listed in the downstream channel list, the CM MUST NOT register on the current downstream channel and MUST restart scanning according to the downstream channel list contained in the configuration file.
+
+Upon reaching the end of the list, the CM MUST begin again with the first sub-TLV in the list. The CM MUST be capable of processing a downstream channel list that contains up to 16 sub-TLVs.
+
+This configuration setting MAY appear multiple times. If this configuration setting appears multiple times, all sub-TLVs MUST be considered part of a single downstream channel list in the order in which they appear in the configuration file. In other words, the sub-TLVs from the first instance of this configuration setting would comprise the first entries in the ordered series, the second instance would comprise the next entries, etc.
+
+#### C.1.1.21.1 Single downstream channel
+
+Upon reaching this sub-TLV in the downstream channel list, the CM MUST attempt to acquire a downstream signal on the specified frequency for a period of time specified by timeout. If a signal is acquired, and it is determined to be unusable by the CM, the CM MAY move on to the next sub-TLV in the downstream channel list without waiting for the timeout to expire.
+
+The CM MUST be capable of processing a downstream channel list that contains multiple single downstream frequency TLVs.
+
+| Type | Length  | Value |
+|------|---------|-------|
+| 41.1 | 6 or 10 |       |
+
+##### C.1.1.21.1.1 Single downstream channel timeout
+
+Timeout is specified in seconds (unsigned). A value of 0 for timeout means no timeout, i.e., the CM attempts to acquire a signal on the specified frequency and if unsuccessful moves immediately to
+
+the next sub-TLV in the downstream channel list. This is an optional parameter in a single downstream channel TLV. If the single downstream channel timeout is omitted, the CM MUST use a default time out of 0.
+
+| Type   | Length | Value   |
+|--------|--------|---------|
+| 41.1.1 | 2      | Timeout |
+
+#### C.1.1.21.1.2 Single downstream channel frequency
+
+Single downstream channel frequency is a required parameter in each single downstream channel TLV; the CM MUST ignore any single downstream channel TLV which lacks this parameter. The DSFrequency MUST be a multiple of 62'500 Hz.
+
+| Type   | Length | Value       |
+|--------|--------|-------------|
+| 41.1.2 | 4      | DSFrequency |
+
+#### C.1.1.21.2 Downstream frequency range
+
+Upon reaching this sub-TLV in the downstream channel list, the CM MUST begin scanning with DSFrequencyStart and progress in steps as indicated by DSFrequencyStepSize until reaching DSFrequencyEnd, and then repeat for a period of time specified by timeout. If the value of timeout is less than the time necessary for the CM to complete one full scan of all channels in the downstream frequency range, the CM MUST complete one full scan and then move on to the next sub-TLV in the downstream channel list. Note, DSFrequencyEnd may be less than DSFrequencyStart, which indicates scanning in the downward direction. If a signal has been acquired on all available channels between DSFrequencyStart and DSFrequencyEnd (inclusive), and all channels have been determined to be unusable by the CM, the CM MAY move on to the next sub-TLV in the downstream channel list without waiting for the Timeout to expire.
+
+The CM MUST be capable of processing a downstream channel list that contains multiple downstream frequency range TLVs.
+
+| Type | Length   | Value |
+|------|----------|-------|
+| 41.2 | 18 or 22 |       |
+
+##### C.1.1.21.2.1 Downstream frequency range timeout
+
+Timeout is specified in seconds (unsigned). A value of 0 for timeout means no timeout, i.e., the CM attempts to acquire a signal once on each frequency within the defined range, and if unsuccessful moves immediately to the next sub-TLV in the downstream channel list. This is an optional parameter in a downstream frequency range TLV. If the downstream frequency range timeout is omitted, the CM MUST use a default time out of 0.
+
+| Type   | Length | Value   |
+|--------|--------|---------|
+| 41.2.1 | 2      | Timeout |
+
+##### C.1.1.21.2.2 Downstream frequency range start
+
+Downstream frequency range start is a required parameter in each downstream frequency range TLV; the CM MUST ignore any downstream frequency range TLV that lacks this parameter. Downstream frequency range start MUST be a multiple of 62'500 Hz.
+
+| Type   | Length | Value            |
+|--------|--------|------------------|
+| 41.2.2 | 4      | DSFrequencyStart |
+
+#### C.1.1.21.2.3 Downstream frequency range end
+
+Downstream frequency range end is a required parameter in each downstream frequency range TLV; the CM MUST ignore any downstream frequency range TLV that lacks this parameter. Downstream frequency range end MUST be a multiple of 62'500 Hz.
+
+| Type   | Length | Value          |
+|--------|--------|----------------|
+| 41.2.3 | 4      | DSFrequencyEnd |
+
+#### C.1.1.21.2.4 Downstream frequency range step size
+
+Downstream frequency range step size is a required parameter in each downstream frequency range TLV; the CM MUST ignore any downstream frequency range TLV which lacks this parameter. Downstream frequency range step size specifies the increments in Hz by which the CM MUST scan through the downstream frequency range.
+
+The CM MUST support a minimum downstream frequency step size of 6'000'000 Hz. The CM MAY support downstream frequency step sizes less than 6'000'000 Hz.
+
+| Type   | Length | Value               |
+|--------|--------|---------------------|
+| 41.2.4 | 4      | DSFrequencyStepSize |
+
+#### C.1.1.21.3 Default scanning
+
+Upon reaching this sub-TLV in the downstream channel list, the CM MUST begin scanning according to its default scanning algorithm (which may be vendor-dependent), and repeat for a period of time specified by timeout. When the CM reaches a valid downstream frequency during default scanning, the CM completes initial ranging and DHCP, and receives a new config file, via TFTP. If the config file does not contain TLV 41, the CM continues with registration. If the config file contains TLV 41 and the current downstream channel is not explicitly listed in the downstream channel list, the CM restarts scanning according to the downstream channel list contained in the configuration file.
+
+Timeout is specified in seconds (unsigned). If the value of timeout is less than the time necessary for the CM to complete one full scan of all channels in the default scanning algorithm, the CM MUST complete one full scan and move on to the next sub-TLV in the downstream channel list. A value of 0 for timeout means no timeout, i.e., the CM scans all available frequencies once, then moves to the next sub-TLV in the downstream channel list.
+
+The CM MUST be capable of processing a downstream channel list that contains multiple default scanning TLVs.
+
+| Type | Length | Value   |
+|------|--------|---------|
+| 41.3 | 2      | Timeout |
+
+#### C.1.1.21.4 Examples illustrating usage of the downstream channel list
+
+Assume that a modem has been provisioned to receive a config file with a downstream channel list consisting of several single downstream channel (TLV 41.1) entries, a downstream frequency range (TLV 41.2) entry, a default scanning (TLV 41.3) entry, and no timeout entries.
+
+When the modem first boots up, it locks onto the first downstream channel it can find and goes through initial ranging. After completing the ranging process, the modem downloads the config file with the downstream channel list. The modem then checks its current downstream frequency against the frequencies explicitly listed in the single downstream channel (TLV 41.1) entries and the downstream frequency range entry (TLV 41.2) of the downstream channel list, ignoring the default scan (TLV 41.3) entry at this point. If the current channel is not explicitly in the single downstream channel entries in the list or within the downstream frequency range entry in the list, the modem moves to the first sub-TLV in the TLV 41 list and attempts to lock onto that channel. If the modem is able to lock onto that frequency, it again tries to range and download a config file. Assuming that the modem receives the same config file, the modem would then proceed with registration.
+
+If the modem is not able to lock on the first sub-TLV in the downstream channel list, it moves onto the next entry in the list and so on. If it reaches the downstream frequency range TLV, it will begin scanning at the downstream frequency range start, incrementing the frequency by the downstream frequency step size, and ending at the downstream frequency range end. If the CM finds a valid downstream frequency within the downstream frequency range, the modem ranges and downloads a config file. Assuming that the config file has not changed, the modem continues with registration on that channel.
+
+However, if it reaches the default scanning sub-TLV without successfully registering, the modem starts its "default scan" process. If, during the course of its default scan, the modem finds a DS channel that it can lock onto, is able to complete ranging, and is able to download a config file, it will do so. However, at that point, the modem once again checks which downstream channels are explicitly in the list and acts accordingly.
+
+As a second, less likely example, assume that a modem has been provisioned to receive a config file with a downstream channel list containing only a default scanning (TLV 41.3) entry. When the modem first boots up, it locks onto the first downstream channel it can find and goes through initial ranging. After completing the ranging process, the modem downloads the config file with the downstream channel list. Since the default scanning is the only parameter in the downstream channel list, the downstream frequency on which the CM locked is not explicitly included, so the CM continues to scan according to its algorithm. The CM will not register on a channel until it receives a config file with a downstream frequency explicitly listed in the downstream channel list or a config file with no downstream channel list.
+
+#### C.1.1.22 Downstream unencrypted traffic (DUT) filtering encoding
+
+This parameter enables the CM to perform downstream unencrypted traffic filtering as described in the DOCSIS layer 2 virtual private network specification [L2VPN]. If the CM does not support the DUT filtering capability, it MUST ignore the DUT filtering encoding TLV.
+
+DUT filtering encoding:
+
+| Type | Length                                       | Value |
+|------|----------------------------------------------|-------|
+| 45   | Length/value tuples are specified in [L2VPN] |       |
+
+### C.1.2 Configuration-file-specific settings
+
+These settings are found only in the configuration file. They MUST NOT be forwarded to the CMDS in the registration request.
+
+#### C.1.2.1 End-of-data marker
+
+This is a special marker for end of data. It has no length or value fields.
+
+| Type |
+|------|
+| 255  |
+
+#### C.1.2.2 Pad configuration setting
+
+This has no length or value fields and is only used following the end of data marker to pad the file to an integral number of 32-bit words.
+
+| Type |
+|------|
+| 0    |
+
+#### C.1.2.3 Software upgrade filename
+
+The filename of the software upgrade file for the CM. The filename is a fully qualified directory-path name. The file is expected to reside on a TFTP server identified in a configuration setting option defined in clause D.2.2. See also clause 12.1.
+
+| Type | Length | Value     |
+|------|--------|-----------|
+| 9    | n      | File name |
+
+#### C.1.2.4 SNMP write-access control
+
+This object makes it possible to disable SNMP "set" access to individual MIB objects. Each instance of this object controls access to all of the writeable MIB objects whose object ID (OID) prefix matches. This object may be repeated to disable access to any number of MIB objects.
+
+| Type | Length | Value                        |
+|------|--------|------------------------------|
+| 10   | n      | OID prefix plus control flag |
+
+Where n is the size of the ASN.1 basic encoding rules [ITU-T X.690] encoding of the OID prefix plus one byte for the control flag.
+
+The control flag may take values:
+
+- 0: Allow write-access;
+- 1: Disallow write-access.
+
+Any OID prefix may be used. The null OID 0.0 may be used to control access to all MIB objects. (The OID 1.3.6.1 will have the same effect.)
+
+When multiple instances of this object are present and overlap, the longest (most specific) prefix has precedence. Thus, one example might be
+
+- someTable: Disallow write-access;
+- someTable.1.3: Allow write-access.
+
+This example disallows access to all objects in someTable except for some Table.1.3.
+
+### C.1.2.5 SNMP MIB object
+
+This object allows arbitrary SNMP MIB objects to be set via the TFTP-Registration process.
+
+| Type | Length | Value            |
+|------|--------|------------------|
+| 11   | n      | Variable binding |
+
+The value is an SNMP VarBind as defined in [RFC 1157]. The VarBind is encoded in ASN.1 basic encoding rules, just as it would be if part of an SNMP set request.
+
+The cable modem MUST treat this object as if it were part of an SNMP set request with the following caveats:
+
+- It MUST treat the request as fully authorized (it cannot refuse the request for lack of privilege).
+- SNMP write-control provisions (see previous clause) do not apply.
+- No SNMP response is generated by the CM.
+
+This object MAY be repeated with different VarBinds to "set" a number of MIB objects. All such sets MUST be treated as if simultaneous.
+
+Each VarBind MUST be limited to 255 bytes.
+
+### C.1.2.6 CPE Ethernet MAC address
+
+This object configures the CM with the Ethernet MAC address of a CPE device (see clause 5.1.2.3.1). This object may be repeated to configure any number of CPE device addresses.
+
+| Type | Length | Value                       |
+|------|--------|-----------------------------|
+| 14   | 6      | Ethernet MAC address of CPE |
+
+### C.1.2.7 Software upgrade TFTP server
+
+The IP address of the TFTP server on which the software upgrade file for the CM resides. See clauses 12.1 and C.1.2.3.
+
+| Type | Length | Value              |
+|------|--------|--------------------|
+| 21   | 4      | ip1, ip2, ip3, ip4 |
+
+### C.1.2.8 SnmpV3 kickstart value
+
+Compliant CMs MUST understand the following TLV and its sub-elements and be able to kickstart SNMPv3 access to the CM regardless of whether the CMs are operating in 1.0 mode or 1.1 mode.
+
+| Type | Length | Value     |
+|------|--------|-----------|
+| 34   | n      | Composite |
+
+Up to 5 of these objects may be included in the configuration file. Each results in an additional row being added to the usmDHKickstartTable and the usmUserTable and results in an agent public number being generated for those rows.
+
+#### C.1.2.8.1 SnmpV3 kickstart security name
+
+| Type | Length | Value                      |
+|------|--------|----------------------------|
+| 34.1 | 2-16   | UTF8 encoded security name |
+
+For the ASCII character set, the UTF8 and the ASCII encodings are identical. Normally, this will be specified as one of the DOCSIS built-in USM users, e.g., "docsisManager", "docsisOperator", "docsisMonitor", "docsisUser". The security name is NOT zero terminated. This is reported in the usmDHKickStartTable as usmDHKickStartSecurityName and in the usmUserTable as usmUserName and usmUserSecurityName.
+
+#### C.1.2.8.2 SnmpV3 kickstart manager public number
+
+| Type | Length | Value                                                              |
+|------|--------|--------------------------------------------------------------------|
+| 34.2 | n      | Manager's Diffie-Helman public number expressed as an octet string |
+
+This number is the Diffie-Helman public number derived from a privately generated (by the manager or operator) random number and transformed according to [RFC 2786]. This is reported in the usmDHKickStartTable as usmKickStartMgrPublic. When combined with the object reported in the same row as usmKickStartMyPublic, it can be used to derive the keys in the related row in the usmUserTable.
+
+#### C.1.2.9 Manufacturer code verification certificate
+
+The manufacturer code verification certificate (M-CVC) for secure software downloading specified by Appendix D of [DOCS8]. The CM config file MUST contain this M-CVC and/or C-CVC defined in clause C.1.2.10 in order to allow the 1.1-compliant CM to download the code file from the TFTP server whether or not the CM is provisioned to run with BPI, BPI+, or none of them. See Appendix D of [DOCS8] for details.
+
+| Type | Length | Value                                |
+|------|--------|--------------------------------------|
+| 32   | n      | Manufacturer CVC (DER-encoded ASN.1) |
+
+If the length of the M-CVC exceeds 254 bytes, the M-CVC MUST be fragmented into two or more successive type 32 elements. Each fragment, except the last, MUST be 254 bytes in length. The CM reconstructs the M-CVC by concatenating the contents (value of the TLV) of successive type 32 elements in the order in which they appear in the configuration file. For example, the first byte following the length field of the second type 32 element is treated as if it immediately follows the last byte of the first type 32 element.
+
+#### C.1.2.10 Co-signer code verification certificate
+
+The co-signer code verification certificate (C-CVC) for secure software downloading specified by Appendix D of [DOCS8]. The CM configuration file MUST contain this C-CVC and/or M-CVC defined in clause C.1.2.9 in order to allow the 1.1-compliant CM to download the code file from TFTP server whether or not the CM is provisioned to run with BPI, BPI+, or none of them. See Appendix D of [DOCS8] for details.
+
+| Type | Length | Value                             |
+|------|--------|-----------------------------------|
+| 33   | n      | Co-signer CVC (DER-encoded ASN.1) |
+
+If the length of the C-CVC exceeds 254 bytes, the C-CVC MUST be fragmented into two or more successive type 33 elements. Each fragment, except the last, MUST be 254 bytes in length. The CM reconstructs the C-CVC by concatenating the contents (value of the TLV) of successive type 33 elements in the order in which they appear in the config file. For example, the first byte following the length field of the second Type 33 element is treated as if it immediately follows the last byte of the first Type 33 element.
+
+#### C.1.2.11 SNMPv3 notification receiver
+
+This TLV specifies a network management station that will receive notifications from the modem when it is in co-existence mode. Up to 10 of these elements may be included in the configuration file.
+
+| Type | Length | Value     |
+|------|--------|-----------|
+| 38   | n      | Composite |
+
+##### C.1.2.11.1 SNMPv3 notification receiver IP address
+
+This sub-TLV specifies the IP address of the notification receiver.
+
+| Type | Length | Value              |
+|------|--------|--------------------|
+| 38.1 | 4      | ip1, ip2, ip3, ip4 |
+
+##### C.1.2.11.2 SNMPv3 notification receiver UDP port number
+
+This sub-TLV specifies the UDP port number of the notification receiver. If this sub-TLV is not present, the default value of 162 should be used.
+
+| Type | Length | Value           |
+|------|--------|-----------------|
+| 38.2 | 2      | UDP port number |
+
+##### C.1.2.11.3 SNMPv3 notification receiver trap type
+
+| Type | Length | Value     |
+|------|--------|-----------|
+| 38.3 | 2      | Trap type |
+
+This sub-TLV specifies the type of trap to send. The trap type may take values:
+
+- 1 = SNMP v1 trap in an SNMP v1 packet;
+- 2 = SNMP v2c trap in an SNMP v2c packet;
+- 3 = SNMP inform in an SNMP v2c packet;
+- 4 = SNMP v2c trap in an SNMP v3 packet;
+- 5 = SNMP inform in an SNMP v3 packet.
+
+##### C.1.2.11.4 SNMPv3 notification receiver timeout
+
+This sub-TLV specifies the timeout value to use when sending an inform message to the notification receiver.
+
+| Type | Length | Value                |
+|------|--------|----------------------|
+| 38.4 | 2      | Time in milliseconds |
+
+#### C.1.2.11.5 SNMPv3 notification receiver retries
+
+This sub-TLV specifies the number of times to retry sending an inform message if an acknowledgement is not received.
+
+| Type | Length | Value             |
+|------|--------|-------------------|
+| 38.5 | 2      | Number of retries |
+
+#### C.1.2.11.6 SNMPv3 notification receiver filtering parameters
+
+This sub-TLV specifies the ASN.1 formatted object identifier of the snmpTrapOID value that identifies the notifications to be sent to the notification receiver. SNMP V3 allows the specification of which trap OIDs are to be sent to a trap receiver. This object specifies the OID of the root of a trap filter sub-tree. All traps with a trap OID contained in this trap filter sub-tree MUST be sent to the trap receiver. This object starts with the ASN.1 universal type 6 (object identifier) byte, then the ASN.1 length field, then the ASN.1 encoded object identifier components.
+
+| Type | Length | Value      |
+|------|--------|------------|
+| 38.6 | n      | Filter OID |
+
+#### C.1.2.11.7 SNMPv3 notification receiver security name
+
+This sub-TLV specifies the V3 security name to use when sending a V3 notification. This sub-TLV is only used if trap type is set to 4 or 5. This name must be a name specified in a configuration file TLV Type 34 as part of the DH kickstart procedure. The notifications will be sent using the authentication and privacy keys calculated by the modem during the DH kickstart procedure.
+
+This sub-TLV is not required for trap type = 1, 2 or 3 above. If it is not supplied for a trap type of 4 or 5, then the V3 notification will be sent in the noAuthNoPriv security level using the security name "@config".
+
+| Type | Length | Value         |
+|------|--------|---------------|
+| 38.7 | n      | Security name |
+
+#### C.1.2.12 Multicast MAC address
+
+This object configures the CM with a static multicast MAC address that is being provisioned into the CM. This object may be repeated to configure any number of static multicast MAC addresses. The CM MUST support a minimum of 10 static multicast MAC addresses. The CM MUST forward any multicast frames that match the static multicast MAC address from the cable network to the CMCI subject to the provisions of clause 5.1.2.3.2. IGMP has no impact on this forwarding.
+
+| Type | Length | Value                        |
+|------|--------|------------------------------|
+| 42   | 6      | Static multicast MAC address |
+
+### C.1.3 Registration request/response-specific encodings
+
+These encodings are not found in the configuration file, but are included in the registration request and option 60 of the DHCP request. Some encodings are also used in the registration response.
+
+The CM MUST include all modem capabilities encodings that are subject to negotiation with the CMTS in its registration request. Modem capabilities encodings that are not subject to negotiation with the CMTS are explicitly stated in the description of the particular modem capability. The CMTS MUST include modem capabilities in the registration response.
+
+### C.1.3.1 Modem capabilities encoding
+
+The value field describes the capabilities of a particular modem, i.e., implementation-dependent limits on the particular feature or number of features that the modem can support. It is composed from a number of encapsulated type/length/value fields. The encapsulated subtypes define the specific capabilities for the modem in question. Note that the subtype fields defined are only valid within the encapsulated capabilities configuration setting string.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 5    | n      |       |
+
+The set of possible encapsulated fields is described below.
+
+All these capabilities are to be included in both the registration request and option 60 of the DHCP request unless the description of the capability explicitly prohibits this.
+
+#### C.1.3.1.1 Concatenation support
+
+If the value field is a 1, the CM requests concatenation support from the CMTS.
+
+| Type | Length | On/Off |
+|------|--------|--------|
+| 5.1  | 1      | 1 or 0 |
+
+#### C.1.3.1.2 DOCS version
+
+DOCS version of this modem.
+
+| Type | Length | Value                                                           |
+|------|--------|-----------------------------------------------------------------|
+| 5.2  | 1      | 0: DOCS v1.0<br>1: DOCS v1.1<br>2: DOCS v2.0<br>3-255: Reserved |
+
+If this tuple is absent, the CMTS MUST assume DOCS v1.0 operation. The absence of this tuple or the value 'DOCSIS 1.0' does not necessarily mean the CM only supports DOCS 1.0 functionality – the CM MAY indicate it supports other individual capabilities with other modem capability encodings (refer to clause G.2). This capability is provided by the CM for the benefit of the CMTS, the operation of the CM is not affected by the value returned by the CMTS.
+
+#### C.1.3.1.3 Fragmentation support
+
+If the value field is a 1, the CM requests fragmentation support from the CMTS.
+
+| Type | Length | Value  |
+|------|--------|--------|
+| 5.3  | 1      | 1 or 0 |
+
+#### C.1.3.1.4 Payload header suppression support
+
+If the value field is a 1, the CM requests payload header suppression support from the CMTS.
+
+| Type | Length | Value  |
+|------|--------|--------|
+| 5.4  | 1      | 1 or 0 |
+
+#### C.1.3.1.5 IGMP support
+
+If the value field is a 1, the CM supports DOCS 1.1-compliant IGMP.
+
+| Type | Length | Value  |
+|------|--------|--------|
+| 5.5  | 1      | 1 or 0 |
+
+NOTE – This CM capability is not subject to negotiation with the CMTS. The CM MUST include this capability in the DHCP request, but MUST NOT include this capability in the registration request. If a CMTS does receive this capability with in a registration request it MUST return the capability with the same value in the registration response.
+
+#### C.1.3.1.6 Privacy support
+
+The value indicates the BPI support of the CM.
+
+| Type | Length | Value                                                    |
+|------|--------|----------------------------------------------------------|
+| 5.6  | 1      | 0: BPI support<br>1: BPI plus support<br>2-255: reserved |
+
+#### C.1.3.1.7 Downstream SAID support
+
+This field shows the number of downstream SAIDs the modem can support.
+
+| Type | Length | Value                                         |
+|------|--------|-----------------------------------------------|
+| 5.7  | 1      | Number of downstream SAIDs the CM can support |
+
+If the number of SAIDs is 0, the modem can support only 1 SAID.
+
+#### C.1.3.1.8 Upstream SID support
+
+This field shows the number of upstream SIDs the modem can support.
+
+| Type | Length | Value                                      |
+|------|--------|--------------------------------------------|
+| 5.8  | 1      | Number of upstream SIDs the CM can support |
+
+If the number of SIDs is 0, that means the modem can support only 1 SID.
+
+#### C.1.3.1.9 Optional filtering support
+
+This field shows the optional filtering support in the modem.
+
+| Type | Length | Value                                                                                                                             |
+|------|--------|-----------------------------------------------------------------------------------------------------------------------------------|
+| 5.9  | 1      | Packet filtering support array<br>bit #0: 802.1P filtering<br>bit #1: 802.1Q filtering<br>bit #2-7: Reserved, MUST be set to zero |
+
+NOTE – This CM capability is not subject to negotiation with the CMTS. The CM MUST include this capability in the DHCP request, but MUST NOT include this capability in the registration request. If a
+
+CMTS does receive this capability with in a registration request, it MUST return the capability with the same value in the registration response.
+
+#### C.1.3.1.10 Transmit equalizer taps per modulation interval
+
+This field shows the maximal number of pre-equalizer taps per modulation interval T supported by the CM.
+
+NOTE – All CMs MUST support T-spaced equalizer coefficients. CM support of 2 or 4 taps per modulation interval is optional. If this tuple is missing, it is implied that the CM only supports T-spaced equalizer coefficients. A CM MUST include this capability in the registration request and its value MUST be 1.
+
+| Type | Length | Value     |
+|------|--------|-----------|
+| 5.10 | 1      | 1, 2 or 4 |
+
+#### C.1.3.1.11 Number of transmit equalizer taps
+
+This field shows the number of equalizer taps that are supported by the CM.
+
+NOTE – All CMs MUST support an equalizer length of at least 8 symbols. CM support of up to 64 T-spaced, T/2-spaced or T/4-spaced taps is optional. If this tuple is missing, it is implied that the CM only supports an equalizer length of 8 taps. A CM MUST include this capability in the registration request and its value MUST be 24.
+
+| Type | Length | Value   |
+|------|--------|---------|
+| 5.11 | 1      | 8 to 64 |
+
+#### C.1.3.1.12 DCC support
+
+The value is the DCC support of the CM.
+
+| Type | Length | Value                                          |
+|------|--------|------------------------------------------------|
+| 5.12 | 1      | 0: DCC is not supported<br>1: DCC is supported |
+
+#### C.1.3.1.13 IP filters support
+
+This field shows the number of IP filters that are supported by the CM.
+
+| Type | Length | Value    |
+|------|--------|----------|
+| 5.13 | 2      | 16-65535 |
+
+NOTE – This CM capability is not subject to negotiation with the CMTS. The CM MUST include this capability in the DHCP request, but MUST NOT include this capability in the registration request. If a CMTS does receive this capability in a registration request it MUST return the capability with the same value in the registration response.
+
+#### C.1.3.1.14 LLC filters support
+
+This field shows the number of LLC filters that are supported by the CM.
+
+| Type | Length | Value    |
+|------|--------|----------|
+| 5.14 | 2      | 10-65535 |
+
+NOTE – This CM capability is not subject to negotiation with the CMTS. The CM MUST include this capability in the DHCP request, but MUST NOT include this capability in the registration request. If a
+
+CMTS does receive this capability in a registration request it MUST return the capability with the same value in the registration response.
+
+#### C.1.3.1.15 Expanded unicast SID space
+
+Indicates if the CM can support the expanded unicast SID space.
+
+| Type | Length | Value                                                                                        |
+|------|--------|----------------------------------------------------------------------------------------------|
+| 5.15 | 1      | 0: Expanded unicast SID space is not supported<br>1: Expanded unicast SID space is supported |
+
+#### C.1.3.1.16 Ranging hold-off support
+
+The CM indicates support for the ranging hold-off feature by reporting its ranging class ID in the value field. The low order 16 bits of the ranging class ID is comprised of a static bit map that indicates the device type. The CM sets the bits of the devices to 1 in the bit map. Only a stand-alone cable modem will set Bit #0. For example, a standalone CM would report a value of 1; a CM with a CableHome PS would report a value of 2; a CM with a PacketCable MTA, and an ePS would report a value of 6; an eSTB would report a value of 8 although it contained an eCM. Bits 16 through 31 are derived from the configuration file as described in clause C.1.1.17.1.4. The ranging class ID is not negotiable. The value field in the REG-RSP is ignored by the CM.
+
+| Type | Length | Value                                                                                                                                                                          |
+|------|--------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 5.16 | 4      | Ranging class ID (bitmap)<br>Bit #0: CM<br>Bit #1: ePS<br>Bit #2: eMTA<br>Bit #3: DSG/eSTB<br>Bits 4 through 15: Reserved<br>Bits 16 through 31: CM ranging class ID extension |
+
+#### C.1.3.1.17 L2VPN capability
+
+This capability indicates whether the CM is compliant with the DOCSIS layer 2 virtual private network feature as defined in [L2VPN]. The CM MAY support the DOCSIS layer 2 virtual private network feature as defined in [L2VPN].
+
+| Type | Length                                       | Value |
+|------|----------------------------------------------|-------|
+| 5.17 | Length/value tuples are specified in [L2VPN] |       |
+
+#### C.1.3.1.18 L2VPN eSAFE host capability
+
+This capability encoding informs the CMTS of the type and MAC address of an eSAFE host embedded with a CM that supports the L2VPN feature. A CM MUST NOT include L2VPN eSAFE host capability TLV in the registration request or DHCP option 60 if it does not indicate support for [L2VPN] via the L2VPN capability encoding.
+
+| Type | Length                                       | Value |
+|------|----------------------------------------------|-------|
+| 5.18 | Length/value tuples are specified in [L2VPN] |       |
+
+#### C.1.3.1.19 Downstream unencrypted traffic (DUT) filtering
+
+This capability indicates whether the CM supports the DUT filtering feature as defined in the DOCSIS layer 2 virtual private network specification [L2VPN]. The CM MAY support DUT filtering.
+
+| Type | Length                                       | Value |
+|------|----------------------------------------------|-------|
+| 5.19 | Length/value tuples are specified in [L2VPN] |       |
+
+#### C.1.3.2 Vendor ID encoding
+
+The value field contains the vendor identification specified by the three-byte vendor-specific organization unique identifier of the CM MAC address.
+
+The vendor ID MUST be used in a registration request, but MUST NOT be used as a stand-alone configuration file element. It MAY be used as a sub-field of the vendor-specific information field in a configuration file. When used as a sub-field of the vendor-specific information field, this identifies the vendor ID of the CMs that are intended to use this information. When the vendor ID is used in a registration request, then it is the vendor ID of the CM sending the request.
+
+| Type | Length | Value      |
+|------|--------|------------|
+| 8    | 3      | v1, v2, v3 |
+
+#### C.1.3.3 Modem IP address
+
+For backward compatibility with DOCS v 1.0. Replaced by 'TFTP server provisioned modem address'.
+
+| Type | Length | Value      |
+|------|--------|------------|
+| 12   | 4      | IP address |
+
+#### C.1.3.4 Service(s) not available response
+
+This configuration setting MUST be included in the registration response message if the CMTS is unable or unwilling to grant any of the requested classes of service that appeared in the registration request. Although the value applies only to the failed service class, the entire registration request MUST be considered to have failed (none of the class-of-service configuration settings are granted).
+
+| Type | Length | Value                             |
+|------|--------|-----------------------------------|
+| 13   | 3      | Class ID, type, confirmation code |
+
+Class ID is the class-of-service class from the request that is not available.
+
+Type is the specific class-of-service object within the class that caused the request to be rejected.
+
+Confirmation code (refer to clause C.4).
+
+### C.1.3.5 Vendor-specific capabilities
+
+Vendor-specific data about the CM that is to be included in the REG-REQ, but which is not part of the configuration file, if present, MUST be encoded in the vendor-specific capabilities (VSC) (code 44) using the vendor ID field (refer to clause C.1.3.2) to specify which TLV tuples apply to which vendors products. The vendor ID MUST be the first TLV embedded inside VSC. If the first TLV inside VSIF is not a vendor ID, then the TLV MUST be discarded.
+
+This configuration setting MAY appear multiple times. The same vendor ID MAY appear multiple times. There MUST NOT be more than one vendor ID TLV inside a single VSC.
+
+| Type | Length | Value                 |
+|------|--------|-----------------------|
+| 44   | n      | Per vendor definition |
+
+Example:
+
+Configuration with vendor A-specific fields and vendor B-specific fields:
+
+VSC (44) + n (number of bytes inside this VSC)
+
+8 (vendor ID type) + 3 (length field) + vendor ID of vendor
+
+Vendor-specific type #1 + length of the field + value #1
+
+Vendor-specific type #2 + length of the field + value #2
+
+### C.1.4 Dynamic-service-message-specific encodings
+
+These encodings are not found in the configuration file, nor in the registration request/response signalling. They are only found in DSA-REQ, DSA-RSP, DSA-ACK, DSC-REQ, DSC-RSP, DSC-ACK and DSD-REQ messages (see clauses 8.3.12 through 8.3.18).
+
+#### C.1.4.1 HMAC-Digest
+
+The HMAC-Digest setting is a keyed message digest. If privacy is enabled, the HMAC-digest attribute MUST be the final attribute in the dynamic service message's attribute list. The message digest is performed over the all of the dynamic service parameters (starting immediately after the MAC management message header and up to, but not including, the HMAC digest setting), other than the HMAC-digest, in the order in which they appear within the packet.
+
+Inclusion of the keyed digest allows the receiver to authenticate the message. The HMAC-Digest algorithm, and the upstream and downstream key generation requirements are documented in [DOCS8].
+
+This parameter contains a keyed hash used for message authentication. The HMAC algorithm is defined in [RFC 2104]. The HMAC algorithm is specified using a generic cryptographic hash algorithm. Baseline privacy uses a particular version of HMAC that employs the secure hash algorithm (SHA-1), defined in [FIPS 180-1].
+
+A summary of the HMAC-digest attribute format is shown below. The fields are transmitted from left to right.
+
+| Type | Length | Value                               |
+|------|--------|-------------------------------------|
+| 27   | 20     | A 160-bit (20-octet) keyed SHA hash |
+
+#### C.1.4.2 Authorization block
+
+The authorization block contains an authorization "hint". The specifics of the contents of this "hint" are beyond the scope of this Recommendation, but include [ITU-T J.163].
+
+The authorization block MAY be present in CM-initiated DSA-REQ and DSC-REQ messages, and CMTS-initiated DSA-RSP and DSC-RSP messages. This parameter MUST NOT be present in CMTS-initiated DSA-REQ and DSC-REQ messages, nor CM-initiated DSA-RSP and DSC-RSP messages.
+
+The authorization block information applies to the entire content of the message. Thus, only a single authorization block per message MAY be present. The authorization block, if present, MUST be passed to the authorization module in the CMTS. The authorization block information is only processed by the authorization module.
+
+| Type | Length | Value                |
+|------|--------|----------------------|
+| 30   | n      | Sequence of n octets |
+
+#### C.1.4.3 Key sequence number
+
+The value shows the key sequence number of the BPI+ authorization key that is used to calculate the HMAC-digest in case that the privacy is enabled.
+
+| Type | Length | Value                           |
+|------|--------|---------------------------------|
+| 31   | 1      | Auth key sequence number (0-15) |
+
+### C.2 Quality-of-service-related encodings
+
+#### C.2.1 Packet classification encodings
+
+The following type/length/value encodings MUST be used in both the configuration file, registration messages and dynamic service messages to encode parameters for packet classification and scheduling. All multi-octet quantities are in network-byte order, i.e., the octet containing the most-significant bits is the first transmitted on the wire.
+
+A classifier MUST contain at least one encoding from clause C.2.1.5, "IP packet classification encodings", clause C.2.1.6, "Ethernet LLC packet classification encodings", or C.2.1.7, "IEEE 802.1P/Q packet classification encodings".
+
+The following configuration settings MUST be supported by all CMs that are compliant with this Recommendation. All CMTSs MUST support classification of downstream packets based on IP header fields (see clause C.2.1.5).
+
+##### C.2.1.1 Upstream packet classification encoding
+
+This field defines the parameters associated with an upstream classifier.
+
+Note that the same subtype fields defined are valid for both the encapsulated upstream and downstream packet classification configuration setting string. These type fields are not valid in other encoding contexts.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 22   | n      |       |
+
+##### C.2.1.2 Downstream packet classification encoding
+
+This field defines the parameters associated with a downstream classifier.
+
+Note that the same subtype fields defined are valid for both the encapsulated upstream and downstream flow classification configuration setting string. These type fields are not valid in other encoding contexts.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 23   | n      |       |
+
+### C.2.1.3 General packet classifier encodings
+
+#### C.2.1.3.1 Classifier reference
+
+The value of the field specifies a reference for the classifier. This value is unique per dynamic service message, configuration file or registration request message.
+
+| Type      | Length | Value |
+|-----------|--------|-------|
+| [22/23].1 | 1      | 1-255 |
+
+#### C.2.1.3.2 Classifier identifier
+
+The value of the field specifies an identifier for the classifier. This value is unique to per service flow. The CMTS assigns the packet classifier identifier.
+
+| Type      | Length | Value    |
+|-----------|--------|----------|
+| [22/23].2 | 2      | 1-65'535 |
+
+#### C.2.1.3.3 Service flow reference
+
+The value of the field specifies a service flow reference that identifies the corresponding service flow.
+
+In all packet classifier TLVs that occur in any message where the service flow ID is not known (e.g., CM-initiated DSA-REQ and REG-REQ), this TLV MUST be included. In all packet classifier TLVs that occur in a DSC-REQ and CMTS-initiated DSA-REQ messages, the service flow reference MUST NOT be specified.
+
+| Type      | Length | Value    |
+|-----------|--------|----------|
+| [22/23].3 | 2      | 1-65'535 |
+
+#### C.2.1.3.4 Service flow identifier
+
+The value of this field specifies the service flow ID that identifies the corresponding service flow.
+
+In packet classifier TLVs where the service flow ID is not known, this TLV MUST NOT be included (e.g., CM-initiated DSA-REQ and REG-REQ). In packet classifier TLVs that occur in a DSC-REQ and CMTS-initiated DSA-REQ message, the service flow ID MUST be specified.
+
+| Type      | Length | Value           |
+|-----------|--------|-----------------|
+| [22/23].4 | 4      | 1-4'294'967'295 |
+
+#### C.2.1.3.5 Rule priority
+
+The value of the field specifies the priority for the classifier, which is used for determining the order of the classifier. A higher value indicates higher priority.
+
+Classifiers that appear in configuration files and registration messages MAY have priorities in the range 0-255 with the default value 0. Classifiers that appear in DSA/DSC message MUST have priorities in the range 64-191, with the default value 64.
+
+| Type      | Length | Value |
+|-----------|--------|-------|
+| [22/23].5 | 1      |       |
+
+#### C.2.1.3.6 Classifier activation state
+
+The value of this field specifies whether this classifier should become active in selecting packets for the service flow. An inactive classifier is typically used with an AdmittedQosParamSet to ensure resources are available for later activation. The actual activation of the classifier depends both on this attribute and on the state of its service flow. If the service flow is not active, then the classifier is not used, regardless of the setting of this attribute.
+
+| Type      | Length | Value                    |
+|-----------|--------|--------------------------|
+| [22/23].6 | 1      | 0: Inactive<br>1: Active |
+
+The default value is 1: Activate the classifier.
+
+#### C.2.1.3.7 Dynamic service change action
+
+When received in a dynamic service change request, this indicates the action that should be taken with this classifier.
+
+| Type      | Length | Value                                                                          |
+|-----------|--------|--------------------------------------------------------------------------------|
+| [22/23].7 | 1      | 0: DSC add classifier<br>1: DSC replace classifier<br>2: DSC delete classifier |
+
+#### C.2.1.4 Classifier error encodings
+
+This field defines the parameters associated with classifier errors.
+
+| Type      | Length | Value |
+|-----------|--------|-------|
+| [22/23].8 | n      |       |
+
+A classifier error encoding consists of a single classifier error parameter set, which is defined by the following individual parameters: errored parameter, confirmation code and error message.
+
+The classifier error encoding is returned in REG-RSP, DSA-RSP and DSC-RSP messages to indicate the reason for the recipient's negative response to a classifier establishment request in a REG-REQ, DSA-REQ or DSC-REQ message.
+
+On failure, the REG-RSP, DSA-RSP or DSC-RSP MUST include one classifier error encoding for at least one failed classifier requested in the REG-REQ, DSA-REQ or DSC-REQ message. A classifier error encoding for the failed classifier MUST include the confirmation code and errored parameter and MAY include an error message. If some classifier sets are rejected but other classifier sets are accepted, then classifier error encodings MUST be included for only the rejected classifiers. On success of the entire transaction, the RSP or ACK message MUST NOT include a classifier error encoding.
+
+Multiple classifier error encodings may appear in a REG-RSP, DSA-RSP or DSC-RSP message, since multiple classifier parameters may be in error. A message with even a single classifier error encoding MUST NOT contain any other protocol classifier encodings (e.g., IP, 802.1P/Q).
+
+A classifier error encoding MUST NOT appear in any REG-REQ, DSA-REQ or DSC-REQ messages.
+
+#### C.2.1.4.1 Errored parameter
+
+The value of this parameter identifies the subtype of a requested classifier parameter in error in a rejected classifier request. A classifier error parameter set MUST have exactly one errored parameter TLV within a given classifier error encoding.
+
+| Subtype     | Length | Value                                |
+|-------------|--------|--------------------------------------|
+| [22/23].8.1 | n      | Classifier encoding subtype in error |
+
+If the length is one, then the value is the single-level subtype where the error was found, e.g., 7 indicates an invalid change action. If the length is two, then the value is the multi-level subtype where the error was found, e.g., 9-2 indicates an invalid IP protocol value.
+
+#### C.2.1.4.2 Error code
+
+This parameter indicates the status of the request. A non-zero value corresponds to the confirmation code as described in clause C.4. A classifier error parameter set MUST have exactly one error code within a given classifier error encoding.
+
+| Subtype     | Length | Value             |
+|-------------|--------|-------------------|
+| [22/23].8.2 | 1      | Confirmation code |
+
+A value of okay (0) indicates that the classifier request was successful. Since a classifier error parameter set applies only to errored parameters, this value MUST NOT be used.
+
+#### C.2.1.4.3 Error message
+
+This subtype is optional in a classifier error parameter set. If present, it indicates a text string to be displayed on the CM console and/or log that further describes a rejected classifier request. A classifier error parameter set MAY have zero or one error message subtypes within a given classifier error encoding.
+
+| Subtype     | Length | Value                                      |
+|-------------|--------|--------------------------------------------|
+| [22/23].8.3 | n      | Zero-terminated string of ASCII characters |
+
+NOTE 1 – The length n includes the terminating zero.
+
+NOTE 2 – The entire classifier encoding message MUST have a total length of less than 256 characters.
+
+### C.2.1.5 IP packet classification encodings
+
+This field defines the parameters associated with IP packet classification.
+
+| Type      | Length | Value |
+|-----------|--------|-------|
+| [22/23].9 | n      |       |
+
+#### C.2.1.5.1 IP type of service range and mask
+
+The values of the field specify the matching parameters for the IP ToS byte range and mask. An IP packet with IP ToS byte value "ip-tos" matches this parameter if  $tos-low \leq (ip-tos \text{ AND } tos-mask) \leq tos-high$ . If this field is omitted, then comparison of the IP packet ToS byte for this entry is irrelevant.
+
+| Type        | Length | Value                       |
+|-------------|--------|-----------------------------|
+| [22/23].9.1 | 3      | tos-low, tos-high, tos-mask |
+
+### C.2.1.5.2 IP protocol
+
+The value of the field specifies the matching value for the IP protocol field [b-RFC 1700]. If this parameter is omitted, then comparison of the IP header protocol field for this entry is irrelevant.
+
+There are two special IP protocol field values: "256" matches traffic with any IP protocol value, and "257" matches both TCP and UDP traffic. An entry that includes an IP protocol field value greater than 257 MUST be invalidated for comparisons (i.e., no traffic can match this entry).
+
+| Type        | Length | Value        |
+|-------------|--------|--------------|
+| [22/23].9.2 | 2      | prot1, prot2 |
+
+Valid range: 0-257
+
+### C.2.1.5.3 IP source address
+
+The value of the field specifies the matching value for the IP source address. An IP packet with IP source address "ip-src" matches this parameter if  $src = (ip\text{-}src \text{ AND } smask)$ , where "smask" is the parameter from clause C.2.1.5.4. If this parameter is omitted, then comparison of the IP packet source address for this entry is irrelevant.
+
+| Type        | Length | Value                  |
+|-------------|--------|------------------------|
+| [22/23].9.3 | 4      | src1, src2, src3, src4 |
+
+### C.2.1.5.4 IP source mask
+
+The value of the field specifies the mask value for the IP source address, as described in clause C.2.1.5.3. If this parameter is omitted, then the default IP source mask is 255.255.255.255.
+
+| Type        | Length | Value                          |
+|-------------|--------|--------------------------------|
+| [22/23].9.4 | 4      | smask1, smask2, smask3, smask4 |
+
+### C.2.1.5.5 IP destination address
+
+The value of the field specifies the matching value for the IP destination address. An IP packet with IP destination address "ip-dst" matches this parameter if  $dst = (ip\text{-}dst \text{ AND } dmask)$ , where "dmask" is the parameter from clause C.2.1.5.6. If this parameter is omitted, then comparison of the IP packet destination address for this entry is irrelevant.
+
+| Type        | Length | Value                  |
+|-------------|--------|------------------------|
+| [22/23].9.5 | 4      | dst1, dst2, dst3, dst4 |
+
+### C.2.1.5.6 IP destination mask
+
+The value of the field specifies the mask value for the IP destination address, as described in clause C.2.1.5.5, "IP destination address". If this parameter is omitted, then the default IP destination mask is 255.255.255.255.
+
+| Type        | Length | Value                          |
+|-------------|--------|--------------------------------|
+| [22/23].9.6 | 4      | dmask1, dmask2, dmask3, dmask4 |
+
+### C.2.1.5.7 TCP/UDP source port start
+
+The value of the field specifies the low-end TCP/UDP source port value. An IP packet with TCP/UDP port value "src-port" matches this parameter if  $sportlow \leq src\text{-}port \leq sporthigh$ . If this
+
+parameter is omitted, then the default value of sportlow is 0. This parameter is irrelevant for non-TCP/UDP IP traffic.
+
+| Type        | Length | Value                |
+|-------------|--------|----------------------|
+| [22/23].9.7 | 2      | sportlow1, sportlow2 |
+
+#### C.2.1.5.8 TCP/UDP source port end
+
+The value of the field specifies the high-end TCP/UDP source port value. An IP packet with TCP/UDP port value "src-port" matches this parameter if sportlow  $\leq$  src-port  $\leq$  sporthigh. If this parameter is omitted, then the default value of sporthigh is 65'535. This parameter is irrelevant for non-TCP/UDP IP traffic.
+
+| Type        | Length | Value                  |
+|-------------|--------|------------------------|
+| [22/23].9.8 | 2      | sporthigh1, sporthigh2 |
+
+#### C.2.1.5.9 TCP/UDP destination port start
+
+The value of the field specifies the low-end TCP/UDP destination port value. An IP packet with TCP/UDP port value "dst-port" matches this parameter if dportlow  $\leq$  dst-port  $\leq$  dporthigh. If this parameter is omitted, then the default value of dportlow is 0. This parameter is irrelevant for non-TCP/UDP IP traffic.
+
+| Type        | Length | Value                |
+|-------------|--------|----------------------|
+| [22/23].9.9 | 2      | dportlow1, dportlow2 |
+
+#### C.2.1.5.10 TCP/UDP destination port end
+
+The value of the field specifies the high-end TCP/UDP destination port value. An IP packet with TCP/UDP port value "dst-port" matches this parameter if dportlow  $\leq$  dst-port  $\leq$  dporthigh. If this parameter is omitted, then the default value of dporthigh is 65'535. This parameter is irrelevant for non-TCP/UDP IP traffic.
+
+| Type         | Length | Value                  |
+|--------------|--------|------------------------|
+| [22/23].9.10 | 2      | dporthigh1, dporthigh2 |
+
+### C.2.1.6 Ethernet LLC packet classification encodings
+
+This field defines the parameters associated with Ethernet LLC packet classification.
+
+| Type       | Length | Value |
+|------------|--------|-------|
+| [22/23].10 | n      |       |
+
+#### C.2.1.6.1 Destination MAC address
+
+The values of the field specifies the matching parameters for the MAC destination address. An Ethernet packet with MAC destination address "etherdst" matches this parameter if dst = (etherdst AND msk). If this parameter is omitted, then comparison of the Ethernet MAC destination address for this entry is irrelevant.
+
+| Type         | Length | Value                                                                  |
+|--------------|--------|------------------------------------------------------------------------|
+| [22/23].10.1 | 12     | dst1, dst2, dst3, dst4, dst5, dst6, msk1, msk2, msk3, msk4, msk5, msk6 |
+
+### C.2.1.6.2 Source MAC address
+
+The value of the field specifies the matching value for the MAC source address. If this parameter is omitted, then comparison of the Ethernet MAC source address for this entry is irrelevant.
+
+| Type         | Length | Value                              |
+|--------------|--------|------------------------------------|
+| [22/23].10.2 | 6      | src1, src2, src3, src4, src5, src6 |
+
+### C.2.1.6.3 Ethertype/DSAP/MacType
+
+Type, eprot1 and eprot2 indicate the format of the layer 3 protocol ID in the Ethernet packet as follows:
+
+If type = 0, the rule does not use the layer 3 protocol type as a matching criterion. If type = 0, then eprot1, eprot2 are ignored when considering whether a packet matches the current rule.
+
+If type = 1, the rule applies only to frames which contain an Ethertype value. Ethertype values are contained in packets using the DEC-Intel-Xerox (DIX) encapsulation or the RFC 1042 subnetwork access protocol (SNAP) encapsulation formats. If type = 1, then eprot1, eprot2 gives the 16-bit value of the Ethertype that the packet must match in order to match the rule.
+
+If type = 2, the rule applies only to frames using the IEEE 802.2 encapsulation format with a destination service (DSAP) other than 0xAA (which is reserved for SNAP). If type = 2, the lower 8 bits of the eprot1, eprot2, MUST match the DSAP byte of the packet in order to match the rule.
+
+If type = 3, the rule applies only to MAC management messages (FC field 1100001x) with a "type" field of its MAC management message header (see clause 6.3.1) between the values of eprot1 and eprot2, inclusive. As exceptions, the following MAC management message types MUST NOT be classified, and are always transmitted on the primary service flow:
+
+- Type 4: RNG-REQ;
+- Type 6: REG-REQ;
+- Type 7: REG-RSP;
+- Type 14: REG-ACK.
+
+If type = 4, the rule is considered a "catch-all" rule that matches all data PDU packets. The rule does not match MAC management messages. The values of eprot1 and eprot2 are ignored in this case.
+
+If the Ethernet frame contains an 802.1P/Q tag header (i.e., Ethertype 0x8100), this object applies to the embedded Ethertype field within the 802.1P/Q header.
+
+Other values of type are reserved. If this TLV is omitted, then comparison of either the Ethertype or IEEE 802.2 DSAP for this rule is irrelevant.
+
+| Type         | Length | Value                |
+|--------------|--------|----------------------|
+| [22/23].10.3 | 3      | type, eprot1, eprot2 |
+
+### C.2.1.7 IEEE 802.1P/Q packet classification encodings
+
+This field defines the parameters associated with IEEE 802.1P/Q packet classification.
+
+| Type       | Length | Value |
+|------------|--------|-------|
+| [22/23].11 | n      |       |
+
+#### C.2.1.7.1 IEEE 802.1P user\_priority
+
+The values of the field specify the matching parameters for the IEEE 802.1P user\_priority bits. An Ethernet packet with IEEE 802.1P user\_priority value "priority" matches these parameters if  $\text{pri-low} \leq \text{priority} \leq \text{pri-high}$ . If this field is omitted, then comparison of the IEEE 802.1P user\_priority bits for this entry is irrelevant.
+
+If this parameter is specified for an entry, then Ethernet packets without IEEE 802.1Q encapsulation MUST NOT match this entry. If this parameter is specified for an entry on a CM that does not support forwarding of IEEE 802.1Q-encapsulated traffic, then this entry MUST NOT be used for any traffic.
+
+| Type         | Length | Value             |
+|--------------|--------|-------------------|
+| [22/23].11.1 | 2      | pri-low, pri-high |
+
+Valid range: 0-7 for pri-low and pri-high.
+
+#### C.2.1.7.2 IEEE 802.1Q vlan\_ID
+
+The value of the field specify the matching value for the IEEE 802.1Q vlan\_id bits. Only the first (i.e., most-significant) 12 bits of the specified vlan\_id field are significant; the final four bits MUST be ignored for comparison. If this field is omitted, then comparison of the IEEE 802.1Q vlan\_id bits for this entry is irrelevant.
+
+If this parameter is specified for an entry, then Ethernet packets without IEEE 802.1Q encapsulation MUST NOT match this entry. If this parameter is specified for an entry on a CM that does not support forwarding of IEEE 802.1Q-encapsulated traffic, then this entry MUST NOT be used for any traffic.
+
+| Type         | Length | Value              |
+|--------------|--------|--------------------|
+| [22/23].11.2 | 2      | vlan_id1, vlan_id2 |
+
+#### C.2.1.7.3 Vendor-specific classifier parameters
+
+This allows vendors to encode vendor-specific classifier parameters using the DOCSIS extension field. The vendor ID MUST be the first TLV embedded inside vendor-specific classifier parameters. If the first TLV inside vendor-specific classifier parameters is not a vendor ID, then the TLV MUST be discarded (refer to clause C.1.1.17).
+
+| Type       | Length | Value |
+|------------|--------|-------|
+| [22/23].43 | n      |       |
+
+### C.2.2 Service flow encodings
+
+The following type/length/value encodings MUST be used in the configuration file, registration messages, and dynamic service messages to encode parameters for service flows. All multi-octet quantities are in network-byte order, i.e., the octet containing the most-significant bits is the first transmitted on the wire.
+
+The following configuration settings MUST be supported by all CMs which are compliant with this Recommendation.
+
+### C.2.2.1 Upstream service flow encodings
+
+This field defines the parameters associated with upstream scheduling for a service flow. It is somewhat complex in that it is composed from a number of encapsulated type/length/value fields.
+
+Note that the encapsulated upstream and downstream service flow configuration setting strings share the same subtype field numbering plan, because many of the subtype fields defined are valid for both types of configuration settings. These type fields are not valid in other encoding contexts.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 24   | n      |       |
+
+### C.2.2.2 Downstream service flow encodings
+
+This field defines the parameters associated with downstream scheduling for a service flow. It is somewhat complex in that it is composed from a number of encapsulated type/length/value fields.
+
+Note that the encapsulated upstream and downstream flow classification configuration setting strings share the same subtype field numbering plan, because many of the subtype fields defined are valid for both types of configuration settings except service flow encodings. These type fields are not valid in other encoding contexts.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 25   | n      |       |
+
+### C.2.2.3 General service flow encodings
+
+#### C.2.2.3.1 Service flow reference
+
+The service flow reference is used to associate a packet classifier encoding with a service flow encoding. A service flow reference is only used to establish a service flow ID. Once the service flow exists and has assigned a service flow ID, the service flow reference MUST no longer be used. The service flow reference is unique per configuration file, registration message exchange, or dynamic service add message exchange.
+
+| Type      | Length | Value    |
+|-----------|--------|----------|
+| [24/25].1 | 2      | 1-65'535 |
+
+#### C.2.2.3.2 Service flow identifier
+
+The service flow identifier is used by the CMTS as the primary reference of a service flow. Only the CMTS can issue a service flow identifier. It uses this parameterization to issue service flow identifiers in CMTS-initiated DSA-Requests and in its REG/DSA-Response to CM-initiated REG/DSA-Requests. The CM specifies the SFID of a service flow using this parameter in a DSC-REQ message. Both the CM and CMTS MAY use this TLV to encode service flow IDs in a DSD-REQ.
+
+The configuration file MUST NOT contain this parameter.
+
+| Type      | Length | Value           |
+|-----------|--------|-----------------|
+| [24/25].2 | 4      | 1-4'294'967'295 |
+
+#### C.2.2.3.3 Service identifier
+
+The value of this field specifies the service identifier assigned by the CMTS to a service flow with a non-null AdmittedQosParamSet or ActiveQosParamSet. This is used in the bandwidth allocation
+
+MAP to assign upstream bandwidth. This field MUST be present in CMTS-initiated DSA-REQ or DSC-REQ message related to establishing an admitted or active upstream service flow. This field MUST also be present in REG-RSP, DSA-RSP and DSC-RSP messages related to the successful establishment of an admitted or active upstream service flow. This field MUST NOT be present in settings related to downstream service flows; the service identifier only applies to upstream service flows.
+
+Even though a service flow has been successfully admitted or activated (i.e., has an assigned service ID) the service flow ID MUST be used for subsequent DSx message signalling as it is the primary handle for a service flow. If a service flow is no longer admitted or active (via DSC-REQ) its service ID MAY be reassigned by the CMTS.
+
+| Subtype   | Length | Value                   |
+|-----------|--------|-------------------------|
+| [24/25].3 | 2      | SID (low-order 14 bits) |
+
+#### C.2.2.3.4 Service class name
+
+The value of the field refers to a predefined CMTS service configuration to be used for this service flow.
+
+| Type      | Length  | Value                                      |
+|-----------|---------|--------------------------------------------|
+| [24/25].4 | 2 to 16 | Zero-terminated string of ASCII characters |
+
+NOTE – The length includes the terminating zero.
+
+When the service class name is used in a service flow encoding, it indicates that all the unspecified QoS parameters of the service flow need to be provided by the CMTS. It is up to the operator to synchronize the definition of service class names in the CMTS and in the configuration file.
+
+#### C.2.2.3.5 Quality of service parameter set type
+
+This parameter MUST appear within every service flow encoding, with the exception of service flow encodings in the DSD-REQ where the quality of service parameter set type has no value. It specifies the proper application of the QoS parameter set or service class name: to the provisioned set, the admitted set, and/or the active set. When two QoS parameter sets are the same, a multi-bit value of this parameter MAY be used to apply the QoS parameters to more than one set. A single message MAY contain multiple QoS parameter sets in separate type 24/25 service flow encodings for the same service flow. This allows specification of the QoS parameter sets when their parameters are different. Bit 0 is the LSB of the value field.
+
+For every service flow that appears in a registration request or registration response message, there MUST be a service flow encoding that specifies a ProvisionedQosParamSet. This service flow encoding, or other service flow encoding(s), MAY also specify an admitted and/or active set.
+
+Any service flow encoding that appears in a dynamic service message MUST NOT specify the ProvisionedQosParamSet.
+
+| Type      | Length | Value                                                                 |
+|-----------|--------|-----------------------------------------------------------------------|
+| [24/25].6 | 1      | Bit #0: Provisioned set<br>Bit #1: Admitted set<br>Bit #2: Active set |
+
+**Table C.2 – Values used in REG-REQ and REG-RSP messages**
+
+| Value | Messages                                                                                                                                         |
+|-------|--------------------------------------------------------------------------------------------------------------------------------------------------|
+| 001   | Apply to provisioned set only                                                                                                                    |
+| 011   | Apply to provisioned and admitted set; and perform admission control                                                                             |
+| 101   | Apply to provisioned and active sets; perform admission control on admitted set in separate service flow encoding; and activate the service flow |
+| 111   | Apply to provisioned, admitted and active sets; perform admission control; and activate this service flow                                        |
+
+**Table C.3 – Values used in REG-REQ, REG-RSP and dynamic service messages**
+
+| Value | Messages                                                                                                                                               |
+|-------|--------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 010   | Perform admission control and apply to admitted set                                                                                                    |
+| 100   | Check against admitted set in separate service flow encoding; perform admission control if needed; activate this service flow; and apply to active set |
+| 110   | Perform admission control and activate this service flow; apply parameters to both admitted and active sets                                            |
+
+The value 000 is used only in dynamic service change messages. It is used to set the active and admitted sets to Null (see clause 10.1.7.4).
+
+A CMTS MUST handle a single update to each of the active and admitted QoS parameter sets. The ability to process multiple service flow encodings that specify the same QoS parameter set is NOT required, and is left as a vendor-specific function. If a DSA/DSC contains multiple updates to a single QoS parameter set and the vendor does not support such updates, then the CMTS MUST reply with error code 2, reject-unrecognized-configuration-setting.
+
+#### C.2.2.4 Service flow error encodings
+
+This field defines the parameters associated with service flow errors.
+
+| Type      | Length | Value |
+|-----------|--------|-------|
+| [24/25].5 | n      |       |
+
+A service flow error encoding consists of a single service flow error parameter set that is defined by the following individual parameters: errored parameter, confirmation code and error message.
+
+The service flow error encoding is returned in REG-RSP, DSA-RSP and DSC-RSP messages to indicate the reason for the recipient's negative response to a service flow establishment request in a REG-REQ, DSA-REQ or DSC-REQ message.
+
+The service flow error encoding is returned in REG-ACK, DSA-ACK and DSC-ACK messages to indicate the reason for the recipient's negative response to the expansion of a service class name in a corresponding REG-RSP, DSA-RSP or DSC-RSP.
+
+On failure, the REG-RSP, DSA-RSP or DSC-RSP MUST include one service flow error encoding for at least one failed service flow requested in the REG-REQ, DSA-REQ or DSC-REQ message. On failure, the REG-ACK, DSA-ACK or DSC-ACK MUST include one service flow error encoding for at least one failed service class name expansion in the REG-RSP, DSA-RSP or DSC-RSP message. A service flow error encoding for the failed service flow MUST include the confirmation code and errored parameter and MAY include an error message. If some service flow parameter sets are rejected but other service flow parameter sets are accepted, then service flow error encodings MUST be included for only the rejected service flow.
+
+On success of the entire transaction, the RSP or ACK message MUST NOT include a service flow error encoding.
+
+Multiple service flow error encodings MAY appear in a REG-RSP, DSA-RSP, DSC-RSP, REG-ACK, DSA-ACK or DSC-ACK message, since multiple service flow parameters may be in error. A message with even a single service flow error encoding MUST NOT contain any QoS parameters.
+
+A service flow error encoding MUST NOT appear in any REG-REQ, DSA-REQ or DSC-REQ messages.
+
+#### C.2.2.4.1 Errored parameter
+
+The value of this parameter identifies the subtype of a requested service flow parameter in error in a rejected service flow request or service class name expansion response. A service flow error parameter set MUST have exactly one errored parameter TLV within a given service flow error encoding.
+
+| Subtype     | Length | Value                                  |
+|-------------|--------|----------------------------------------|
+| [24/25].5.1 | 1      | Service flow encoding subtype in error |
+
+#### C.2.2.4.2 Error code
+
+This parameter indicates the status of the request. A non-zero value corresponds to the confirmation code as described in clause C.4. A service flow error parameter set MUST have exactly one error code within a given service flow error encoding.
+
+| Subtype     | Length | Value             |
+|-------------|--------|-------------------|
+| [24/25].5.2 | 1      | Confirmation code |
+
+A value of okay (0) indicates that the service flow request was successful. Since a service flow error parameter set only applies to errored parameters, this value MUST NOT be used.
+
+#### C.2.2.4.3 Error message
+
+This subtype is optional in a service flow error parameter set. If present, it indicates a text string to be displayed on the CM console and/or log that further describes a rejected service flow request. A service flow error parameter set MAY have zero or one error message subtypes within a given service flow error encoding.
+
+| Subtype     | Length | Value                                      |
+|-------------|--------|--------------------------------------------|
+| [24/25].5.3 | n      | Zero-terminated string of ASCII characters |
+
+NOTE 1 – The length n includes the terminating zero.
+
+NOTE 2 – The entire service flow encoding message MUST have a total length of less than 256 characters.
+
+### C.2.2.5 Common upstream and downstream quality-of-service parameter encodings
+
+The remaining type 24 and 25 parameters are QoS parameters. Any given QoS parameter type MUST appear zero or one times per service flow encoding.
+
+#### C.2.2.5.1 Traffic priority
+
+The value of this parameter specifies the priority assigned to a service flow. Given two service flows identical in all QoS parameters besides priority, the higher priority service flow SHOULD be given lower delay and higher buffering preference. For otherwise non-identical service flows, the
+
+priority parameter SHOULD NOT take precedence over any conflicting service flow QoS parameter. The specific algorithm for enforcing this parameter is not mandated here.
+
+For upstream service flows, the CMTS SHOULD use this parameter when determining precedence in request service and grant generation, and the CM MUST preferentially select contention request opportunities for priority request service IDs (refer to clause A.2.3) based on this priority and its request/transmission policy (refer to clause C.2.2.6.3).
+
+| Type      | Length | Value                                            |
+|-----------|--------|--------------------------------------------------|
+| [24/25].7 | 1      | 0 to 7 – Higher numbers indicate higher priority |
+
+NOTE – The default priority is 0.
+
+#### C.2.2.5.2 Maximum sustained traffic rate
+
+This parameter is the rate parameter R of a token-bucket-based rate limit for packets. R is expressed in bits per second, and MUST take into account all MAC frame data PDU of the service flow from the byte following the MAC header HCS to the end of the CRC<sup>28</sup>. The number of bytes forwarded (in bytes) is limited during any time interval T by Max(T), as described in equation C.1:
+
+$$\text{Max}(T) = T \times (R/8) + B \quad (\text{C.1})$$
+
+where the parameter B (in bytes) is the maximum traffic burst configuration setting (refer to clause C.2.2.5.3).
+
+NOTE 1 – This parameter does not limit the instantaneous rate of the service flow.
+
+NOTE 2 – The specific algorithm for enforcing this parameter is not mandated here. Any implementation that satisfies the above equation is conformant.
+
+NOTE 3 – If this parameter is omitted or set to zero, then there is no explicitly enforced traffic rate maximum. This field specifies only a bound, not a guarantee that this rate is available.
+
+##### C.2.2.5.2.1 Upstream maximum sustained traffic rate
+
+For an upstream service flow, the CM MUST NOT request bandwidth exceeding the Max(T) requirement in equation C.1 during any interval T because this could force the CMTS to fill MAPs with deferred grants.
+
+The CM MUST defer upstream packets that violate equation C.1 and "rate shape" them to meet the expression, up to a limit as implemented by vendor buffering restrictions.
+
+The CMTS MUST enforce equation C.1 on all upstream data transmissions, including data sent in contention. The CMTS MAY consider unused grants in calculations involving this parameter. The CMTS MAY enforce this limit by any of the following methods:
+
+- discarding over-limit requests;
+- deferring (through zero-length grants) the grant until it is conforming to the allowed limit;  
+or
+- discarding over-limit data packets.
+
+A CMTS MUST report this condition to a policy module. If the CMTS is policing by discarding either packets or requests, the CMTS MUST allow a margin of error between the CM and CMTS algorithms.
+
+| Type | Length | Value                  |
+|------|--------|------------------------|
+| 24.8 | 4      | R (in bits per second) |
+
+<sup>28</sup> The payload size includes every PDU in a concatenated MAC frame.
+
+#### C.2.2.5.2.2 Downstream maximum sustained traffic rate
+
+For a downstream service flow, this parameter is only applicable at the CMTS. The CMTS MUST enforce equation C.1 on all downstream data transmissions. The CMTS MUST NOT forward downstream packets that violates equation C.1 in any interval T. The CMTS SHOULD "rate shape" the downstream traffic by enqueueing packets arriving in excess of equation C.1, and delay them until the equation can be met.
+
+This parameter is not intended for enforcement on the CM.
+
+| Type | Length | Value                  |
+|------|--------|------------------------|
+| 25.8 | 4      | R (in bits per second) |
+
+#### C.2.2.5.3 Maximum traffic burst
+
+The value of this parameter specifies the token bucket size B (in bytes) for this service flow as described in equation C.1. This value is calculated from the byte following the MAC header HCS to the end of the CRC<sup>28</sup>.
+
+The minimum value of B is 1522 bytes. If this parameter is omitted, the default value for B is 3044 bytes. This parameter has no effect unless a non-zero value has been provided for the maximum sustained traffic rate parameter. For an upstream service flow, if B is sufficiently less than the maximum concatenated burst parameter, then enforcement of the rate limit equation will limit the maximum size of a concatenated burst.
+
+| Type      | Length | Value     |
+|-----------|--------|-----------|
+| [24/25].9 | 4      | B (bytes) |
+
+The specific algorithm for enforcing this parameter is not mandated here. Any implementation that satisfies the above equation is conformant.
+
+NOTE – The value of this parameter effects the trade-off between the data latency perceived by an individual application and the traffic engineering requirements of the network. A large value will tend to reduce the latency introduced by rate limiting for applications with bursty traffic patterns. A small value will tend to spread out the bursts of data generated by such applications, which may benefit traffic engineering within the network.
+
+#### C.2.2.5.4 Minimum reserved traffic rate
+
+This parameter specifies the minimum rate, in bit/s, reserved for this service flow. The CMTS SHOULD be able to satisfy bandwidth requests for a service flow up to its minimum reserved traffic rate. If less bandwidth than its minimum reserved traffic rate is requested for a service flow, the CMTS MAY reallocate the excess reserved bandwidth for other purposes. The aggregate minimum reserved traffic rate of all service flows MAY exceed the amount of available bandwidth. This value of this parameter is calculated from the byte following the MAC header HCS to the end of the CRC<sup>28</sup>. If this parameter is omitted, then it defaults to a value of 0 bit/s (i.e., no bandwidth is reserved for the flow by default).
+
+This field is only applicable at the CMTS and MUST be enforced by the CMTS.
+
+| Type       | Length | Value |
+|------------|--------|-------|
+| [24/25].10 | 4      |       |
+
+<sup>28</sup> The payload size includes every PDU in a concatenated MAC frame.
+
+NOTE – The specific algorithm for enforcing the value specified in this field is not mandated here.
+
+#### C.2.2.5.5 Assumed minimum reserved rate packet size
+
+The value of this field specifies an assumed minimum packet size (in bytes) for which the minimum reserved traffic rate will be provided. This parameter is defined in bytes and is specified as the bytes following the MAC header HCS to the end of the CRC<sup>28</sup>. If the service flow sends packets of a size smaller than this specified value, such packets will be treated as being of the size specified in this parameter for calculating the minimum reserved traffic rate.
+
+The CMTS MUST apply this parameter to its minimum reserved traffic rate algorithm. This parameter is used by the CMTS to estimate the per-packet overhead of each packet in the service flow.
+
+If this parameter is omitted, then the default value is CMTS implementation-dependent.
+
+| Type       | Length | Value |
+|------------|--------|-------|
+| [24/25].11 | 2      |       |
+
+#### C.2.2.5.6 Timeout for active QoS parameters
+
+The value of this parameter specifies the maximum duration resources remain unused on an active service flow. If there is no activity on the service flow within this time interval, the CMTS MUST change the active and admitted QoS parameter sets to null. The CMTS MUST signal this resource change with a DSC-REQ to the CM.
+
+| Type       | Length | Value   |
+|------------|--------|---------|
+| [24/25].12 | 2      | Seconds |
+
+This parameter MUST be enforced at the CMTS and SHOULD NOT be enforced at the CM. The parameter is processed by the CMTS for every QoS set contained in registration messages and dynamic service messages. If the parameter is omitted, the default of 0 (i.e., infinite time-out) is assumed. The value specified for the active QoS set must be less than or equal to the corresponding value in the admitted QoS set, which must be less than or equal to the corresponding value in the provisioned/authorized QoS set. If the requested value is too large, the CMTS MAY reject the message or respond with a value less than that requested. If the registration or dynamic service message is accepted by the CMTS and acknowledged by the CM, the active MQoS time-out timer is loaded with the new value of the time-out. The timer is activated if the message activates the associated service flow. The timer is deactivated if the message sets the active QoS set to null.
+
+#### C.2.2.5.7 Timeout for admitted QoS parameters
+
+The value of this parameter specifies the duration that the CMTS MUST hold resources for a service flow's admitted QoS parameter set while they are in excess of its active QoS parameter set. If there is no DSC-REQ to activate the admitted QoS parameter set within this time interval, and there is no DSC to refresh the QoS parameter sets and restart the timeout (see clause 10.1.5.2), the resources that are admitted but not activated MUST be released, and only the active resources retained. The CMTS MUST set the admitted QoS parameter set equal to the active QoS parameter set for the service flow and initiate a DSC-REQ exchange with the CM to inform it of the change.
+
+| Type       | Length | Value   |
+|------------|--------|---------|
+| [24/25].13 | 2      | Seconds |
+
+<sup>28</sup> The payload size includes every PDU in a concatenated MAC frame.
+
+This parameter MUST be enforced at the CMTS and SHOULD NOT be enforced at the CM. The parameter is processed by the CMTS for every QoS set contained in registration messages and dynamic service messages. If the parameter is omitted, the default of 200 seconds is assumed. A value of 0 means that the service flow can remain in the admitted state for an infinite amount of time and MUST NOT be timed out due to inactivity. However, this is subject to policy control by the CMTS. The value specified for the active QoS set must be less than or equal to the corresponding value in the admitted QoS set, which must be less than or equal to the corresponding value in the provisioned/authorized QoS set. If the requested value is too large, the CMTS MAY reject the message or respond with a value less than that requested. If the registration or dynamic service message containing this parameter is accepted by the CMTS and acknowledged by the CM, the admitted QoS timeout timer is loaded with the new value of the timeout. The timer is activated if the message admits resources greater than the active set. The timer is deactivated if the message sets the active QoS set and admitted QoS set equal to each other.
+
+#### C.2.2.5.8 Vendor-specific QoS parameters
+
+This allows vendors to encode vendor-specific QoS parameters using the DOCSIS extension field. The vendor ID MUST be the first TLV embedded inside vendor-specific QoS parameters. If the first TLV inside vendor-specific QoS parameters is not a vendor ID, then the TLV MUST be discarded (refer to clause C.1.1.17).
+
+| Type       | Length | Value |
+|------------|--------|-------|
+| [24/25].43 | n      |       |
+
+#### C.2.2.6 Upstream-specific QoS parameter encodings
+
+##### C.2.2.6.1 Maximum concatenated burst
+
+The value of this parameter specifies the maximum concatenated burst (in bytes) that a service flow is allowed. This parameter is calculated from the FC byte of the concatenation MAC header to the last CRC in the concatenated MAC frame.
+
+A value of 0 means there is no limit. If this parameter is omitted, the default value is 1522.
+
+This field is only applicable at the CM. If defined, this parameter MUST be enforced at the CM.
+
+NOTE 1 – This value does not include any physical layer overhead.
+
+| Type  | Length | Value |
+|-------|--------|-------|
+| 24.14 | 2      |       |
+
+NOTE 2 – This applies only to concatenated bursts. It is legal and, in fact it may be useful, to set this smaller than the maximum Ethernet packet size. Of course, it is also legal to set this equal to or larger than the maximum Ethernet packet size.
+
+NOTE 3 – The maximum size of a concatenated burst can also be limited by the enforcement of a rate limit, if the maximum traffic burst parameter is small enough, and by limits on the size of data grants in the UCD message.
+
+##### C.2.2.6.2 Service flow scheduling type
+
+The value of this parameter specifies which upstream scheduling service is used for upstream transmission requests and packet transmissions. If this parameter is omitted, then best effort service MUST be assumed.
+
+This parameter is only applicable at the CMTS. If defined, this parameter MUST be enforced by the CMTS.
+
+| Type                                                                                                                                         | Length | Value                                                                                                                                                                                                                                                                                                              |
+|----------------------------------------------------------------------------------------------------------------------------------------------|--------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 24.15                                                                                                                                        | 1      | 0: Reserved<br>1: For undefined (CMTS implementation-dependent <sup>a)</sup> )<br>2: For best effort<br>3: For non-real-time polling service<br>4: For real-time polling service<br>5: For unsolicited grant service with activity detection<br>6: For unsolicited grant service<br>7-255: Reserved for future use |
+| <sup>a)</sup> The specific implementation-dependent scheduling service type could be defined in the 24.43 vendor-specific information field. |        |                                                                                                                                                                                                                                                                                                                    |
+
+### C.2.2.6.3 Request/transmission policy
+
+The value of this parameter specifies which IUC opportunities the CM uses for upstream transmission requests and packet transmissions for this service flow, whether requests for this service flow may be piggybacked with data and whether data packets transmitted on this service flow can be concatenated, fragmented or have their payload headers suppressed. For UGS, it also specifies how to treat packets that do not fit into the UGS grant. See clause 10.2 for requirements related to settings of the bits of this parameter for each service flow scheduling type.
+
+This parameter is required for all service flow scheduling types except best effort. If omitted in a best effort service flow QoS parameter set, the default value of zero MUST be used. Bit #0 is the LSB of the value field. Bits are set to 1 to select the behaviour defined below:
+
+| Type  | Length | Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
+|-------|--------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 24.16 | 4      | Bit #0: The service flow MUST NOT use "all CMs" broadcast request opportunities.<br>Bit #1: The service flow MUST NOT use priority request multicast request opportunities (refer to clause A.2.3).<br>Bit #2: The service flow MUST NOT use request/data opportunities for requests.<br>Bit #3: The service flow MUST NOT use request/data opportunities for data.<br>Bit #4: The service flow MUST NOT piggyback requests with data.<br>Bit #5: The service flow MUST NOT concatenate data.<br>Bit #6: The service flow MUST NOT fragment data.<br>Bit #7: The service flow MUST NOT suppress payload headers<br>Bit #8: The service flow MUST drop packets that do not fit in the unsolicited grant size <sup>a) b)</sup><br>All other bits are reserved. |
+
+<sup>a)</sup> This bit only applies to service flows with the unsolicited grant service flow scheduling type, if this bit is set on any other service flow scheduling type it MUST be ignored.
+
+<sup>b)</sup> Packets that classify to an unsolicited grant service flow and are larger than the grant size associated with that service flow are normally transmitted on the primary service flow. This parameter overrides that default behaviour.
+
+NOTE – Data grants include both short and long data grants.
+
+#### C.2.2.6.4 Nominal polling interval
+
+The value of this parameter specifies the nominal interval (in units of microseconds) between successive unicast request opportunities for this service flow on the upstream channel. This parameter is typically suited for real-time and non-real-time polling service.
+
+The ideal schedule for enforcing this parameter is defined by a reference time,  $t_0$ , with the desired transmission times  $t_i = t_0 + i \times \text{interval}$ . The actual poll times,  $t'_i$ , MUST be in the range  $t_i \leq t'_i \leq (t_i + \text{jitter})$ , where interval is the value specified with this TLV, and jitter is tolerated poll jitter. The accuracy of the ideal poll times,  $t_i$ , are measured relative to the CMTS master clock used to generate timestamps (refer to clause 9.3).
+
+This field is only applicable at the CMTS. If defined, this parameter MUST be enforced by the CMTS.
+
+| Type  | Length | Value         |
+|-------|--------|---------------|
+| 24.17 | 4      | $\mu\text{s}$ |
+
+#### C.2.2.6.5 Tolerated poll jitter
+
+The value in this parameter specifies the maximum amount of time that the unicast request interval may be delayed from the nominal periodic schedule (measured in microseconds) for this service flow.
+
+The ideal schedule for enforcing this parameter is defined by a reference time,  $t_0$ , with the desired poll times  $t_0 + i \times \text{interval}$ . The actual poll,  $t'_i$ , MUST be in the range  $t_i \leq t'_i \leq t_i + \text{jitter}$ , where jitter is the value specified with this TLV and interval is the nominal poll interval. The accuracy of the
+
+ideal poll times,  $t_i$ , are measured relative to the CMTS master clock used to generate timestamps (refer to clause 9.3).
+
+This parameter is only applicable at the CMTS. If defined, this parameter represents a service commitment (or admission criteria) at the CMTS.
+
+| Type  | Length | Value         |
+|-------|--------|---------------|
+| 24.18 | 4      | $\mu\text{s}$ |
+
+#### C.2.2.6.6 Unsolicited grant size
+
+The value of this parameter specifies the unsolicited grant size in bytes. The grant size includes the entire MAC frame data PDU from the frame control byte to the end of the MAC frame.
+
+This parameter is applicable at the CMTS and MUST be enforced at the CMTS.
+
+| Type  | Length | Value |
+|-------|--------|-------|
+| 24.19 | 2      |       |
+
+NOTE – For UGS, this parameter should be used by the CMTS to compute the size of the unsolicited grant in mini-slots.
+
+#### C.2.2.6.7 Nominal grant interval
+
+The value of this parameter specifies the nominal interval (in units of microseconds) between successive data grant opportunities for this service flow. This parameter is required for unsolicited grant and unsolicited grant with activity detection service flows.
+
+The ideal schedule for enforcing this parameter is defined by a reference time,  $t_0$ , with the desired transmission times  $t_i = t_0 + i \times \text{interval}$ . The actual grant times,  $t'_i$ , MUST be in the range  $t_i \leq t'_i \leq t_i + \text{jitter}$ , where interval is the value specified with this TLV, and jitter is the tolerated grant jitter. When multiple grants per interval are requested, all grants MUST be within this interval, thus the nominal grant interval and tolerated grant jitter MUST be maintained by the CMTS for all grants in this service flow. The accuracy of the ideal grant times,  $t_i$ , are measured relative to the CMTS master clock used to generate timestamps (refer to clause 9.3).
+
+This field is mandatory for unsolicited grant and unsolicited grant with activity detection scheduling types. This field is only applicable at the CMTS, and MUST be enforced by the CMTS.
+
+| Type  | Length | Value         |
+|-------|--------|---------------|
+| 24.20 | 4      | $\mu\text{s}$ |
+
+#### C.2.2.6.8 Tolerated grant jitter
+
+The values in this parameter specifies the maximum amount of time that the transmission opportunities may be delayed from the nominal periodic schedule (measured in microseconds) for this service flow.
+
+The ideal schedule for enforcing this parameter is defined by a reference time,  $t_0$ , with the desired transmission times  $t_i = t_0 + i \times \text{interval}$ . The actual transmission opportunities,  $t'_i$ , MUST be in the range  $t_i \leq t'_i \leq t_i + \text{jitter}$ , where jitter is the value specified with this TLV and interval is the nominal grant interval. The accuracy of the ideal grant times,  $t_i$ , are measured relative to the CMTS master clock used to generate timestamps (refer to clause 9.3).
+
+This field is mandatory for unsolicited grant and unsolicited grant with activity detection scheduling types. This field is only applicable at the CMTS, and MUST be enforced by the CMTS.
+
+| Type  | Length | Value |
+|-------|--------|-------|
+| 24.21 | 4      | μsec  |
+
+#### C.2.2.6.9 Grants per interval
+
+For unsolicited grant service, the value of this parameter indicates the actual number of data grants per nominal grant interval. For unsolicited grant service with activity detection, the value of this parameter indicates the maximum number of active grants per nominal grant interval. This is intended to enable the addition of sessions to an existing unsolicited grant service flow via the dynamic service change mechanism, without negatively impacting existing sessions.
+
+The ideal schedule for enforcing this parameter is defined by a reference time,  $t_0$ , with the desired transmission times  $t_i = t_0 + i \times \text{interval}$ . The actual grant times,  $t'_i$ , MUST be in the range  $t_i \leq t'_i \leq t_i + \text{jitter}$ , where interval is the nominal grant interval, and jitter is the tolerated grant jitter. When multiple grants per interval are requested, all grants MUST be within this interval, thus the nominal grant interval and tolerated grant jitter MUST be maintained by the CMTS for all grants in this service flow.
+
+This field is mandatory for unsolicited grant and unsolicited grant with activity detection scheduling types. This field is only applicable at the CMTS, and MUST be enforced by the CMTS.
+
+| Type  | Length | Value       | Valid range |
+|-------|--------|-------------|-------------|
+| 24.22 | 1      | # of grants | 0-127       |
+
+#### C.2.2.6.10 IP type of service overwrite
+
+The CMTS MUST overwrite IP packets with IP ToS byte value "orig-ip-tos" with the value "new-ip-tos", where  $\text{new-ip-tos} = ((\text{orig-ip-tos AND tos-and-mask}) \text{ OR tos-or-mask})$ . If this parameter is omitted, then the IP packet ToS byte is not overwritten.
+
+This parameter is only applicable at the CMTS. If defined, this parameter MUST be enforced by the CMTS.
+
+| Type  | Length | Value                     |
+|-------|--------|---------------------------|
+| 24.23 | 2      | tos-and-mask, tos-or-mask |
+
+#### C.2.2.6.11 Unsolicited grant time reference
+
+For unsolicited grant service and unsolicited grant service with activity detection, the value of this parameter specifies a reference time,  $t_0$ , from which can be derived the desired transmission times  $t_i = t_0 + i \times \text{interval}$ , where interval is the nominal grant interval (refer to clause C.2.2.6.7). This parameter is applicable only for messages transmitted from the CMTS to the CM, and only when a UGS or UGS-AD service flow is being made active. In such cases, this is a mandatory parameter.
+
+| Type | Length | Value          | Valid range     |
+|------|--------|----------------|-----------------|
+| 24.2 | 4      | CMTS timestamp | 0-4'294'967'295 |
+
+The timestamp specified in this parameter represents a count state of the CMTS 10.24 MHz master clock. Since a UGS or UGS-AD service flow is always activated before transmission of this parameter to the modem, the reference time,  $t_0$ , is to be interpreted by the modem as the ideal time of the next grant only if  $t_0$  follows the current time. If  $t_0$  precedes the current time, the modem can calculate the offset from the current time to the ideal time of the next grant according to:
+
+$$\text{interval} - (((\text{current time} - t_0)/10.24) \text{ modulus interval})$$
+
+where interval is in units of microseconds, and current time and  $t_0$  are in 10.24-MHz units.
+
+### C.2.2.7 Downstream-specific QoS parameter encodings
+
+#### C.2.2.7.1 Maximum downstream latency
+
+The value of this parameter specifies the maximum latency between the reception of a packet by the CMTS on its NSI and the forwarding of the packet to its RF interface.
+
+If defined, this parameter represents a service commitment (or admission criteria) at the CMTS and MUST be guaranteed by the CMTS. A CMTS does not have to meet this service commitment for service flows that exceed their minimum downstream reserved rate.
+
+| Type  | Length | Value         |
+|-------|--------|---------------|
+| 25.14 | 4      | $\mu\text{s}$ |
+
+#### C.2.2.8 Payload header suppression
+
+This field defines the parameters associated with payload header suppression.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 26   | n      |       |
+
+NOTE – The entire payload header suppression TLV MUST have a length of less than 255 characters.
+
+##### C.2.2.8.1 Classifier reference
+
+The value of the field specifies a classifier reference that identifies the corresponding classifier (refer to clause C.2.1.3.1).
+
+| Type | Length | Value |
+|------|--------|-------|
+| 26.1 | 1      | 1-255 |
+
+##### C.2.2.8.2 Classifier identifier
+
+The value of the field specifies a classifier identifier that identifies the corresponding classifier (refer to clause C.2.1.3.2).
+
+| Type | Length | Value    |
+|------|--------|----------|
+| 26.2 | 2      | 1-65'535 |
+
+##### C.2.2.8.3 Service flow reference
+
+The value of the field specifies a service flow reference that identifies the corresponding service flow (refer to clause C.2.2.3.1).
+
+| Type | Length | Value    |
+|------|--------|----------|
+| 26.3 | 2      | 1-65'535 |
+
+##### C.2.2.8.4 Service flow identifier
+
+The value of this field specifies the service flow identifier that identifies the service flow to which the PHS rule applies.
+
+| Type | Length | Value           |
+|------|--------|-----------------|
+| 26.4 | 4      | 1-4'294'967'295 |
+
+#### C.2.2.8.5 Dynamic service change action
+
+When received in a dynamic service change request, this indicates the action that MUST be taken with this payload header suppression byte string.
+
+| Type | Length | Value                                                                               |
+|------|--------|-------------------------------------------------------------------------------------|
+| 26.5 | 1      | 0: Add PHS rule<br>1: Set PHS rule<br>2: Delete PHS rule<br>3: Delete all PHS rules |
+
+The "set PHS rule" command is used to add specific TLVs to a partially defined payload header suppression rule. A PHS rule is partially defined when the PHSF and PHSS values are not both known. A PHS rule becomes fully defined when the PHSF and PHSS values are both known. Once a PHS rule is fully defined, "set PHS rule" MUST NOT be used to modify existing TLVs.
+
+The "Delete all PHS Rules" command is used to delete all PHS rules for a specified service flow. See clause 8.3.15 for details on DSC-REQ required PHS parameters when using this option.
+
+NOTE – An attempt to add a PHS rule that already exists is an error condition.
+
+#### C.2.2.9 Payload header suppression error encodings
+
+This field defines the parameters associated with payload header suppression errors.
+
+| Type | Length | Value |
+|------|--------|-------|
+| 26.6 | n      |       |
+
+A payload header suppression error encoding consists of a single payload header suppression error parameter set which is defined by the following individual parameters: Errored parameter, confirmation code and error message.
+
+The payload header suppression error encoding is returned in REG-RSP, DSA-RSP and DSC-RSP messages to indicate the reason for the recipient's negative response to a payload header suppression rule establishment request in a REG-REQ, DSA-REQ or DSC-REQ message.
+
+On failure, the REG-RSP, DSA-RSP or DSC-RSP MUST include one payload header suppression error encoding for at least one failed payload header suppression rule requested in the REG-REQ, DSA-REQ or DSC-REQ message. A payload header suppression error encoding for the failed payload header suppression rule MUST include the confirmation code and errored parameter and MAY include an error message. If some payload header suppression rule sets are rejected but other payload header suppression rule sets are accepted, then payload header suppression error encodings MUST be included for only the rejected payload header suppression rules. On success of the entire transaction, the RSP or ACK message MUST NOT include a payload header suppression error encoding.
+
+Multiple payload header suppression error encodings MAY appear in a REG-RSP, DSA-RSP or DSC-RSP message, since multiple payload header suppression parameters may be in error. A message with even a single payload header suppression error encoding MUST NOT contain any other protocol payload header suppression encodings (e.g., IP, 802.1P/Q).
+
+A payload header suppression error encoding MUST NOT appear in any REG-REQ, DSA-REQ or DSC-REQ messages.
+
+### C.2.2.9.1 Errored parameter
+
+The value of this parameter identifies the subtype of a requested payload header suppression parameter in error in a rejected payload header suppression request. A payload header suppression error parameter set MUST have exactly one errored parameter TLV within a given payload header suppression error encoding.
+
+| Subtype | Length | Value                                                |
+|---------|--------|------------------------------------------------------|
+| 26.6.1  | 1      | Payload header suppression encoding subtype in error |
+
+### C.2.2.9.2 Error code
+
+This parameter indicates the status of the request. A non-zero value corresponds to the confirmation code as described in clause C.4. A payload header suppression error parameter set MUST have exactly one error code within a given payload header suppression error encoding.
+
+| Subtype | Length | Value             |
+|---------|--------|-------------------|
+| 26.6.2  | 1      | Confirmation code |
+
+A value of okay (0) indicates that the payload header suppression request was successful. Since a payload header suppression error parameter set only applies to errored parameters, this value MUST NOT be used.
+
+### C.2.2.9.3 Error message
+
+This subtype is optional in a payload header suppression error parameter set. If present, it indicates a text string to be displayed on the CM console and/or log that further describes a rejected payload header suppression request. A payload header suppression error parameter set MAY have zero or one error message subtypes within a given payload header suppression error encoding.
+
+| Subtype | Length | Value                                      |
+|---------|--------|--------------------------------------------|
+| 26.6.3  | n      | Zero-terminated string of ASCII characters |
+
+NOTE 1 – The length n includes the terminating zero.
+
+NOTE 2 – The entire payload header suppression encoding message MUST have a total length of less than 256 characters.
+
+## C.2.2.10 Payload header suppression rule encodings
+
+### C.2.2.10.1 Payload header suppression field (PHSF)
+
+The value of this field are the bytes of the headers that MUST be suppressed by the sending entity, and MUST be restored by the receiving entity. In the upstream, the PHSF corresponds to the string of PDU bytes starting with the first byte after the MAC header checksum. For the downstream, the PHSF corresponds to the string of PDU bytes starting with the 13th byte after the MAC header checksum. This string of bytes is inclusive of both suppressed and unsuppressed bytes of the PDU header. The value of the unsuppressed bytes within the PHSF is implementation-dependent.
+
+The ordering of the bytes in the value field of the PHSF TLV string MUST follow the sequence:
+
+*Upstream*
+
+MSB of PHSF value = 1st byte of PDU
+
+2nd MSB of PHSF value = 2nd byte of PDU
+
+...
+
+nth byte of PHSF (LSB of PHSF value) = nth byte of PDU
+
+*Downstream*
+
+MSB of PHSF value = 13th byte of PDU
+
+2nd MSB of PHSF value = 14th byte of PDU
+
+...
+
+nth byte of PHSF (LSB of PHSF value) = (n + 13)th byte of PDU
+
+| Type | Length | Value                      |
+|------|--------|----------------------------|
+| 26.7 | n      | String of bytes suppressed |
+
+The length n MUST always be the same as the value for PHSS.
+
+#### C.2.2.10.2 Payload header suppression index (PHSI)
+
+The payload header suppression index (PHSI) has a value between 1 and 255 that uniquely references the suppressed byte string. The index is unique per service flow in the upstream direction and unique per CM in the downstream direction. The upstream and downstream PHSI values are independent of each other.
+
+| Type | Length | Value       |
+|------|--------|-------------|
+| 26.8 | 1      | Index value |
+
+#### C.2.2.10.3 Payload header suppression mask (PHSM)
+
+The value of this field is used to interpret the values in the payload header suppression field. It is used at both the sending and receiving entities on the link. The PHSM allows fields such as sequence numbers or checksums, that vary in value, to be excluded from suppression with the constant bytes around them suppressed.
+
+| Type | Length | Value                                                                                                                                                                                                                                                                                                                                                                      |
+|------|--------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 26.9 | n      | bit 0: 0 = Do not suppress first byte of the suppression field.<br>1 = Suppress first byte of the suppression field.<br>bit 1: 0 = Do not suppress second byte of the suppression field.<br>1 = Suppress second byte of the suppression field.<br>bit x: 0 = Do not suppress (x + 1) byte of the suppression field.<br>1 = Suppress (x + 1) byte of the suppression field. |
+
+The length n is ceiling (PHSS/8). Bit 0 is the MSB of the value field. The value of each sequential bit in the PHSM is an attribute for the corresponding sequential byte in the PHSF.
+
+If the bit value is a "1" (and verification passes or is disabled), the sending entity MUST suppress the byte, and the receiving entity MUST restore the byte from its cached PHSF. If the bit value is a "0", the sending entity MUST NOT suppress the byte, and the receiving entity MUST restore the byte by using the next byte in the packet.
+
+If this TLV is not included, the default is to suppress all bytes.
+
+#### C.2.2.10.4 Payload header suppression size (PHSS)
+
+The value of this field is the total number of bytes in the payload header suppression field (PHSF) for a service flow that uses payload header suppression.
+
+| Type  | Length | Value                                     |
+|-------|--------|-------------------------------------------|
+| 26.10 | 1      | Number of bytes in the suppression string |
+
+This TLV is used when a service flow is being created. For all packets that get classified and assigned to a service flow with payload header suppression enabled, suppression MUST be performed over the specified number of bytes as indicated by the PHSS and according to the PHSM. If this TLV is included in a service flow definition with a value of 0 bytes, then payload header suppression is disabled. A non-zero value indicates payload header suppression is enabled. Until the PHSS value is known, the PHS rule is considered partially defined, and suppression will not be performed. A PHS rule becomes fully defined when both PHSS and PHSF are known.
+
+#### C.2.2.10.5 Payload header suppression verification (PHSV)
+
+The value of this field indicates to the sending entity whether or not the packet header contents are to be verified prior to performing suppression. If PHSV is enabled, the sender MUST compare the bytes in the packet header with the bytes in the PHSF that are to be suppressed as indicated by the PHSM.
+
+| Type  | Length | Value                         |
+|-------|--------|-------------------------------|
+| 26.11 | 1      | 0: Verify<br>1: Do not verify |
+
+If this TLV is not included, the default is to verify. Only the sender MUST verify suppressed bytes. If verification fails, the payload header MUST NOT be suppressed (refer to clause 10.4.3).
+
+#### C.2.2.10.6 Vendor-specific PHS parameters
+
+This allows vendors to encode vendor-specific PHS parameters using the DOCSIS extension field. The vendor ID MUST be the first TLV embedded inside vendor-specific PHS parameters. If the first TLV inside vendor-specific PHS parameters is not a vendor ID, then the TLV MUST be discarded (refer to clause C.1.1.17).
+
+| Type  | Length | Value |
+|-------|--------|-------|
+| 26.43 | n      |       |
+
+### C.3 Encodings for other interfaces
+
+#### C.3.1 Telephone settings option
+
+This configuration setting describes parameters that are specific to telephone return systems. It is composed from a number of encapsulated type/length/value fields (see [DOCS6]).
+
+| Type             | Length | Value |
+|------------------|--------|-------|
+| 15 (= TRI_CFG01) | n      |       |
+
+#### C.3.2 Baseline privacy configuration settings option
+
+This configuration setting describes parameters that are specific to baseline privacy. It is composed from a number of encapsulated type/length/value fields (see [DOCS8]).
+
+| Type          | Length | Value |
+|---------------|--------|-------|
+| 17 (= BP_CFG) | n      |       |
+
+#### C.4 Confirmation code
+
+The confirmation code (CC) provides a common way to indicate failures for registration response, registration ack, dynamic service addition response, dynamic service addition ack, dynamic service delete response, dynamic service change response, dynamic service change ack and dynamic channel change response MAC management messages. The confirmation codes in this clause are used both as message confirmation codes and as error codes in error set encodings that may be carried in these messages.
+
+Confirmation code is one of the following:
+
+- okay/success (0);
+- reject-other (1);
+- reject-unrecognized-configuration-setting (2);
+- reject-temporary/reject-resource (3);
+- reject-permanent/reject-admin (4);
+- reject-not-owner (5);
+- reject-service-flow-not-found (6);
+- reject-service-flow-exists (7);
+- reject-required-parameter-not-present (8);
+- reject-header-suppression (9);
+- reject-unknown-transaction-id (10);
+- reject-authentication-failure (11);
+- reject-add-aborted (12);
+- reject-multiple-errors (13);
+- reject-classifier-not-found (14);
+- reject-classifier-exists (15);
+- reject-PHS-rule-not-found (16);
+- reject-PHS-rule-exists (17);
+- reject-duplicate-reference-ID-or-index-in-message (18);
+- reject-multiple-upstream-service-flows (19);
+- reject-multiple-downstream-service-flows (20);
+- reject-classifier-for-another-service-flow (21);
+- reject-PHS-for-another-service-flow (22);
+- reject-parameter-invalid-for-context (23);
+- reject-authorization-failure (24);
+- reject-temporary-DCC (25).
+
+The confirmation codes MUST be used in the following way:
+
+- Okay or success (0) means the message was received and successful.
+- Reject-other (1) is used when none of the other reason codes apply.
+- Reject-unrecognized-configuration-setting (2) is used when a configuration setting is not recognized or when its value is outside of the specified range.
+- Reject-temporary (3), also known as reject-resource, indicates that the current loading of the CMTS or CM prevents granting the request, but that the request might succeed at another time
+
+- Reject-permanent (4), also known as reject-admin, indicates that, for policy, configuration or capabilities reasons, the request would never be granted unless the CM/TS or CM were manually reconfigured or replaced.
+- Reject-not-owner (5) the requester is not associated with this service flow.
+- Reject-service-flow-not-found (6) the service flow indicated in the request does not exist.
+- Reject-service-flow-exists (7) the service flow to be added already exists.
+- Reject-required-parameter-not-present (8) a required parameter has been omitted.
+- Reject-header-suppression (9) the requested header suppression cannot be supported for whatever reason.
+- Reject-unknown-transaction-id (10) the requested transaction continuation is invalid because the receiving end-point does not view the transaction as being 'in process' (i.e., the message is unexpected or out of order).
+- Reject-authentication-failure (11) the requested transaction was rejected because the message contained an invalid HMAC-Digest, CM/TS-MIC, provisioned IP address or timestamp.
+- Reject-add-aborted (12) the addition of a dynamic service flow was aborted by the initiator of the dynamic service addition.
+- Reject-multiple-errors (13) is used when multiple errors have been detected.
+- Reject-classifier-not-found (14) is used when the request contains an unrecognized classifier ID.
+- Reject-classifier-exists (15) indicates that the ID of a classifier to be added already exists.
+- Reject-PHS-rule-not-found (16) indicates that the request contains an SFID/classifier ID pair for which no PHS rule exists.
+- Reject-PHS-rule-exists (17) indicates that the request to add a PHS rule contains an SFID/classifier ID pair for which a PHS rule already exists.
+- Reject-duplicate-reference-ID-or-index-in-message (18) indicates that the request used an SFR, classifier reference, SFID or classifier ID twice in an illegal way.
+- Reject-multiple-upstream-service-flows (19) is used when DSA/DSC contains parameters for more than one upstream flow.
+- Reject-multiple-downstream-service-flows (20) is used when DSA/DSC contains parameters for more than one downstream flow.
+- Reject-classifier-for-another-service-flow (21) is used in DSA-RSP when the DSA-REQ includes classifier parameters for a SF other than the new SF(s) being added by the DSA.
+- Reject-PHS-for-another-service-flow (22) is used in DSA-RSP when the DSA-REQ includes a PHS rule for a SF other than the new SF(s) being added by the DSA.
+- Reject-parameter-invalid-for-context (23) indicates that the parameter supplied cannot be used in the encoding in which it was included, or that the value of a parameter is invalid for the encoding in which it was included.
+- Reject-authorization-failure (24) the requested transaction was rejected by the authorization module.
+- Reject-temporary-DCC (25) indicates that the requested resources are not available on the current channels at this time, and the CM should re-request them on new channels after completing a channel change in response to a DCC command which the CM/TS will send. If no DCC is received, the CM must wait for a time of at least T14 before re-requesting the resources on the current channels.
+
+#### C.4.1 Confirmation codes for dynamic channel change
+
+The CM may return in the DCC-RSP message an appropriate rejection code from clause C.4. It may also return one of the following confirmation codes, which are unique to DCC-RSP. The confirmation codes MUST be used in the following way:
+
+- depart (180) indicates the CM is on the old channel and is about to perform the jump to the new channel.
+- arrive (181) indicates the CM has performed the jump and has arrived at the new channel.
+- reject-already-there (182) indicates that the CMTS has asked the CM to move to a channel that it is already occupying.
+- reject-20-disable (183) indicates that the CMTS has asked a CM with 2.0 mode disabled to move to a type 3 channel that it cannot use and a UCD substitution was sent in the corresponding DCC-REQ.
+
+#### C.4.2 Confirmation codes for major errors
+
+These confirmation codes MUST be used only as message confirmation codes in REG-ACK, DSA-RSP, DSA-ACK, DSC-RSP or DSC-ACK messages, or as the response code in REG-RSP messages for 1.1 CMs. In general, the errors associated with these confirmation codes make it impossible either to generate an error set that can be uniquely associated with a parameter set in the REG-REQ, DSA-REQ or DSC-REQ message, or to generate a full RSP message.
+
+- reject-major-service-flow-error (200);
+- reject-major-classifier-error (201);
+- reject-major-PHS-rule-error (202);
+- reject-multiple-major-errors (203);
+- reject-message-syntax-error (204);
+- reject-primary-service-flow-error (205);
+- reject-message-too-big (206);
+- reject-invalid-modem-capabilities (207).
+
+The confirmation codes MUST be used only in the following way:
+
+- Reject-major-service-flow-error (200) indicates that the REQ message did not have either a SFR or SFID in a service flow encoding, and that service flow major errors were the only major errors.
+- Reject-major-classifier-error (201) indicates that the REQ message did not have a classifier reference, or did not have both a classifier ID and a service flow ID, and that classifier major errors were the only major errors.
+- Reject-major-PHS-rule-error (202) indicates that the REQ message did not have a both a service flow reference/identifier and a classifier reference/identifier, and that PHS rule major errors were the only major errors.
+- Reject-multiple-major-errors (203) indicates that the REQ message contained multiple major errors of types 200, 201, 202.
+- Reject-message-syntax-error (204) indicates that the REQ message contained syntax error(s) (e.g., a TLV length error) resulting in parsing failure.
+- Reject-primary-service-flow-error (205) indicates that a REG-REQ or REG-RSP message did not define a required primary service flow, or a required primary service flow was not specified active.
+- Reject-message-too-big (206) is used when the length of the message needed to respond exceeds the maximum allowed message size.
+
+- Reject-invalid-modem-capabilities (207) indicates that the REG-REQ contained either an invalid combination of modem capabilities or modem capabilities that are inconsistent with the services in the REG-REQ.
+
+## Annex D
+
+### CM configuration interface specification
+
+(This annex forms an integral part of this Recommendation)
+
+#### D.1 CM IP addressing
+
+##### D.1.1 DHCP fields used by the CM
+
+The following fields MUST be present in the DHCP request from the CM and MUST be set as described below:
+
+- The hardware type (htype) MUST be set to 1 (Ethernet).
+- The hardware length (hlen) MUST be set to 6.
+- The client hardware address (chaddr) MUST be set to the 48-bit MAC address associated with the RF interface of the CM.
+- The "client identifier" option MUST be included, with the hardware type set to 1, and the value set to the same 48 bit MAC address as the chaddr field.
+- Option code 60 (vendor class identifier) – To allow for the differentiation between DOCS 2.0 and DOCS 1.x CM requests, a compliant CM MUST send the following ASCII-coded string in option code 60, "docsis2.0:xxxxxxx". Where xxxxxxx MUST be an ASCII representation of the hexadecimal encoding of the modem capabilities; refer to clause C.1.3.1. For example, the ASCII encoding for the first two TLVs (concatenation and DOCS version) of a DOCS 2.0 modem would be 05nn010101020102. Note that many more TLVs are required for a DOCS2.0 modem and the field "nn" will contain the length of all the TLVs. This example shows only two TLVs for simplicity.
+- The "parameter request list" option MUST be included. The option codes that MUST be included in the list are:
+  - Option code 1 (subnet mask);
+  - Option code 2 (time offset);
+  - Option code 3 (router option);
+  - Option code 4 (time server option);
+  - Option code 7 (log server option).
+
+The following fields are expected in the DHCP response returned to the CM. Fields identified as critical MUST be present in the DHCP response, and fields identified as non-critical SHOULD be present. The CM MUST configure itself with the critical fields from the DHCP response, and, if present, with the non-critical fields.
+
+- The IP address to be used by the CM (yiaddr) (critical).
+- The IP address of the TFTP server for use in the next phase of the bootstrap process (siaddr) (critical).
+- If the DHCP server is on a different network (requiring a relay agent), then the IP address of the relay agent (giaddr).  
+NOTE – This may differ from the IP address of the first hop router (non-critical).
+- The name of the CM configuration file to be read from the TFTP server by the CM (file) (critical).
+- The subnet mask to be used by the CM (subnet mask, option 1) (non-critical).
+
+- The time offset of the CM from universal coordinated time (UTC) (time offset, option 2). This is used by the CM to calculate the local time for use in timestamping error logs (non-critical).
+- A list of addresses of one or more routers to be used for forwarding CM-originated IP traffic (router option, option 3). The CM is not required to use more than one router IP address for forwarding, but MUST use at least one (non-critical).
+- A list of [RFC 868] time-servers from which the current time may be obtained (time server option, option 4) (non-critical).
+- A list of SYSLOG servers to which logging information may be sent (log server option, option 7); see [DOCS5] (non-critical).
+
+If a critical field is missing, or is invalid in the DHCP response during initialization, the CM MUST log an error and re-initialize its MAC and continue channel scanning.
+
+If a non-critical field is missing or is invalid in the DHCP response during initialization, the CM MUST log a warning, ignore the field and go operational, with the following considerations:
+
+- If the subnet mask is missing or is invalid, the CM MUST use the default for the IP of class A, B or C as defined in [RFC 791].
+- If the time server is missing or is invalid, the CM MUST initialize the time for the events to Jan 1, 1970, 0h00.
+
+If the IP address field is missing or is invalid in the DHCP response during renew or rebind, the CM MUST log an error and re-initialize its MAC and continue channel scanning.
+
+If any other critical or non-critical field is missing or is invalid in the DHCP response during renew or rebind, the CM MUST log a warning, ignore the field if it is valid, and stay operational.
+
+To assist the DHCP server in differentiating a CM discovery request from a CPE-side LAN discovery request, a CMTS MUST implement the following:
+
+- All CMTSs MUST support the DHCP relay agent information option [RFC 3046]. Specifically, the CMTS MUST include the 48-bit MAC address of the RF side interface of the CM generating or bridging the DHCP discovery request in the agent remote ID sub-option field before relaying the discovery to a DHCP server.
+- If the CMTS is a router, it MUST use a giaddr field to differentiate between CM and CPE side stations if they are provisioned to be in different IP subnets. Bridging CMTSs SHOULD also provide this functionality.
+
+## D.2 CM configuration
+
+### D.2.1 CM binary configuration file format
+
+The CM-specific configuration data MUST be contained in a file which is downloaded to the CM via TFTP. This is a binary file in the same format defined for DHCP vendor extension data [RFC 2132].
+
+It MUST consist of a number of configuration settings (1 per parameter) each of the form:
+
+Type/Length/Value
+
+Type is a single-octet identifier which defines the parameter.
+
+Length is a single octet containing the length of the value field in octets (not including type and length fields).
+
+Value is from one to 254 octets containing the specific value for the parameter.
+
+The configuration settings MUST follow each other directly in the file, which is a stream of octets (no record markers).
+
+Configuration settings are divided into three types:
+
+- standard configuration settings which MUST be present;
+- standard configuration settings which MAY be present;
+- DOCSIS extension field configuration settings.
+
+CMs MUST be capable of processing all standard configuration settings. CMs MUST ignore any configuration setting present in the configuration file that it cannot interpret. To allow uniform management of CMs conformant to this Recommendation, conformant CMs MUST support a 8192-byte configuration file at a minimum.
+
+Authentication of the provisioning information is provided by two message integrity check (MIC) configuration settings, CM MIC and CMTS MIC.
+
+- CM MIC is a digest which ensures that the data sent from the provisioning server were not modified en route. This is NOT an authenticated digest (it does not include any shared secret).
+- CMTS MIC is a digest used to authenticate the provisioning server to the CMTS during registration. It is taken over a number of fields, one of which is a shared secret between the CMTS and the provisioning server.
+
+Use of the CM MIC allows the CMTS to authenticate the provisioning data without needing to receive the entire file.
+
+Thus the file structure is of the form shown in Figure D.1:
+
+![Figure D.1 – Binary configuration file format diagram](bba553bb36568927a49fc400dd51d21a_img.jpg)
+
+The diagram shows a horizontal sequence of six rectangular boxes representing fields in a configuration file. From left to right, the labels are: 'Configuration setting 1', 'Configuration setting 2', an empty box with a dashed border, 'Configuration setting n', 'CM MIC', and 'CMTS MIC'. The dashed box indicates that there can be multiple configuration settings between the second and the nth setting.
+
+Figure D.1 – Binary configuration file format diagram
+
+J.122\_FD.2.1
+
+**Figure D.1 – Binary configuration file format**
+
+## D.2.2 Configuration file settings
+
+The following configuration settings MUST be included in the configuration file and MUST be supported by all CMs. The CM MUST NOT send a REG-REQ based on a configuration file that lacks these mandatory items:
+
+- Network access configuration setting;
+- CM MIC configuration setting;
+- CMTS MIC configuration setting;
+- End configuration setting;
+- DOCS 1.0 class of service configuration setting.
+
+or:
+
+- Upstream service flow configuration setting;
+- Downstream service flow configuration setting.
+
+NOTE 1 – A DOCS 1.0 CM must be provided with a DOCS 1.0 class of service configuration. A CM conformant with this Recommendation should only be provisioned with DOCS 1.0 class of service configuration information if it is to behave as a DOCS 1.0 CM; otherwise, it should be provisioned with service flow configuration settings.
+
+The following configuration settings MAY be included in the configuration file and if present MUST be supported by all CMs:
+
+- downstream frequency configuration setting;
+- upstream channel id configuration setting;
+- baseline privacy configuration setting;
+- software upgrade filename configuration setting;
+- upstream packet classification setting;
+- downstream packet classification setting;
+- SNMP write-access control;
+- SNMP MIB object;
+- software server IP address;
+- CPE Ethernet MAC address;
+- maximum number of CPEs;
+- maximum number of classifiers;
+- privacy enable configuration setting;
+- payload header suppression;
+- TFTP server timestamp;
+- TFTP server provisioned modem address;
+- pad configuration setting;
+- SNMPv3 notification receiver;
+- enable 2.0 mode;
+- enable test modes;
+- static multicast MAC address.
+
+The following configuration setting MAY be included in the configuration file and, if present and applicable to this type of modem, MUST be supported:
+
+- telephone settings option.
+
+The following configuration settings MAY be included in the configuration file and, if present, MAY be supported by a CM.
+
+- DOCSIS extension field configuration settings.
+
+NOTE 2 – There is a limit on the size of registration request and registration response frames (see clause 8.2.5.2). The configuration file should not be so large as to require the CM or CMTS to exceed that limit.
+
+### D.2.3 Configuration file creation
+
+The sequence of operations required to create the configuration file is as shown in Figures D.2 through D.5.
+
+- 1) Create the type/length/value entries for all the parameters required by the CM.
+
+|                                   |
+|-----------------------------------|
+| Type length value for parameter 1 |
+| Type length value for parameter 2 |
+|                                   |
+| Type length value for parameter n |
+
+**Figure D.2 – Create TLV entries for parameters required by the CM**
+
+- 2) Calculate the CM message integrity check (MIC) configuration setting as defined in clause D.2.3.1 and add to the file following the last parameter using code and length values defined for this field.
+
+|                                   |
+|-----------------------------------|
+| Type length value for parameter 1 |
+| Type length value for parameter 2 |
+|                                   |
+| Type length value for parameter n |
+| Type length value for CM MIC      |
+
+**Figure D.3 – Add CM MIC**
+
+- 3) Calculate the CMTS message integrity check (MIC) configuration setting as defined in clause D.3.1 and add to the file following the CM MIC using code and length values defined for this field.
+
+|                                   |
+|-----------------------------------|
+| Type length value for parameter 1 |
+| Type length value for parameter 2 |
+|                                   |
+| Type length value for parameter n |
+| Type length value for CM MIC      |
+| Type length value for CMTS MIC    |
+
+**Figure D.4 – Add CMTS MIC**
+
+- 4) Add the end-of-data marker.
+
+|                                   |
+|-----------------------------------|
+| Type length value for parameter 1 |
+| Type length value for parameter 2 |
+|                                   |
+| Type length value for parameter n |
+| Type length value for CM MIC      |
+| Type length value for CMTS MIC    |
+| End-of-data marker                |
+
+**Figure D.5 – Add end-of-data marker**
+
+**D.2.3.1 CM MIC calculation**
+
+The CM message integrity check configuration setting MUST be calculated by performing an MD5 digest over the bytes of the configuration setting fields. It is calculated over the bytes of these settings as they appear in the TFTPed image, without regard to TLV ordering or contents. There are two exceptions to this disregard of the contents of the TFTPed image:
+
+- 1) The bytes of the CM MIC TLV itself are omitted from the calculation. This includes the type, length, and value fields.
+- 2) The bytes of the CMTS MIC TLV are omitted from the calculation. This includes the type, length, and value fields.
+
+On receipt of a configuration file, the CM MUST recompute the digest and compare it to the CM MIC configuration setting in the file. If the digests do not match then the configuration file MUST be discarded.
+
+### **D.3 Configuration verification**
+
+It is necessary to verify that the CM's configuration file has come from a trusted source. Thus, the CMTS and the configuration server share an authentication string that they use to verify portions of the CM's configuration in the registration request.
+
+#### **D.3.1 CMTS MIC calculation**
+
+The CMTS message integrity check configuration setting **MUST** be calculated by performing an MD5 digest over the following configuration setting fields, when present in the configuration file, in the order shown:
+
+- downstream frequency configuration setting;
+- upstream channel id configuration setting;
+- network access configuration setting;
+- DOCS 1.0 class-of-service configuration setting;
+- baseline privacy configuration setting;
+- DOCSIS extension field configuration settings;
+- CM MIC configuration setting;
+- maximum number of CPEs;
+- TFTP server timestamp;
+- TFTP server provisioned modem address;
+- upstream packet classification setting;
+- downstream packet classification setting;
+- upstream service flow configuration setting;
+- downstream service flow configuration setting;
+- maximum number of classifiers;
+- privacy enable configuration setting;
+- payload header suppression;
+- subscriber management control;
+- subscriber management CPE IP table;
+- subscriber management filter groups;
+- enable test modes.
+
+The bulleted list specifies the order of operations when calculating the CMTS MIC over configuration setting type fields. The CMTS **MUST** calculate the CMTS MIC over TLVs of the same type in the order they were received. Within type fields, the CMTS **MUST** calculate the CMTS MIC over the subtypes in the order they were received. To allow for correct CMTS MIC calculation by the CMTS, the CM **MUST NOT** reorder configuration file TLVs of the same type or subtypes within any given type in its registration request message.
+
+All configuration setting fields **MUST** be treated as if they were contiguous data when calculating the CM MIC.
+
+The digest **MUST** be added to the configuration file as its own configuration setting field using the CMTS MIC configuration setting encoding.
+
+The authentication string is a shared secret between the provisioning server (which creates the configuration files) and the CMTS. It allows the CMTS to authenticate the CM provisioning. The authentication string is to be used as the key for calculating the keyed CMTS MIC digest as stated in clause D.3.1.1.
+
+The mechanism by which the shared secret is managed is up to the system operator.
+
+On receipt of a configuration file, the CM MUST forward the CMTS MIC as part of the registration request (REG-REQ).
+
+On receipt of a REG-REQ, the CMTS MUST recompute the digest over the included fields and the authentication string and compare it to the CMTS MIC configuration setting in the file. If the digests do not match, the registration request MUST be rejected by setting the authentication failure result in the registration response status field.
+
+#### **D.3.1.1 Digest calculation**
+
+The CMTS MIC digest field MUST be calculated using HMAC-MD5 as defined in [RFC 2104].
+
+## Annex E
+
+### The data-over-cable spanning tree protocol
+
+(This annex forms an integral part of this Recommendation)
+
+Clause 5.1.2.1 requires the use of the spanning tree protocol on CMs that are intended for commercial use and on bridging CMTSs. This annex describes how the IEEE 802.1D spanning tree protocol is adapted to work for data-over-cable systems.
+
+#### E.1 Background
+
+A spanning tree protocol is frequently employed in a bridged network in order to deactivate redundant network connections; i.e., to reduce an arbitrary network mesh topology to an active topology that is a rooted tree that spans all of the network segments. The spanning tree algorithm and protocol should not be confused with the data-forwarding function itself; data forwarding may follow transparent learning bridge rules, or may employ any of several other mechanisms. By deactivating redundant connections, the spanning tree protocol eliminates topological loops, which would otherwise cause data packets to be forwarded forever for many kinds of forwarding devices.
+
+A standard spanning tree protocol [b-ISO/IEC 10038] is employed in most bridged local area networks. This protocol was intended for private LAN use and requires some modification for cable data use.
+
+#### E.2 Public spanning tree
+
+To use a spanning tree protocol in a public-access network such as data-over-cable, several modifications are needed to the basic IEEE 802.1D process. Primarily, the public spanning tree must be isolated from any private spanning tree networks to which it is connected. This is to protect both the public cable network and any attached private networks. Figure E.1 illustrates the general topology.
+
+![Diagram illustrating the spanning tree topology for data-over-cable systems. A central horizontal bus line connects a CMTS (Cable Modem Termination System) on the left to three Cable modems. The top Cable modem is connected to a Bridged private network (represented by an oval). The bottom two Cable modems are connected to another Bridged private network (represented by an oval). The diagram is labeled J.122_FE-1.](1240ac770bfb4a7805029c473fdaadd6_img.jpg)
+
+```
+graph TD; CMTS[CMTS] --- Bus[ ]; Bus --- CM1[Cable modem]; Bus --- CM2[Cable modem]; Bus --- CM3[Cable modem]; CM1 --- BPN1([Bridged private network]); CM2 --- BPN2([Bridged private network]); CM3 --- BPN2;
+```
+
+Diagram illustrating the spanning tree topology for data-over-cable systems. A central horizontal bus line connects a CMTS (Cable Modem Termination System) on the left to three Cable modems. The top Cable modem is connected to a Bridged private network (represented by an oval). The bottom two Cable modems are connected to another Bridged private network (represented by an oval). The diagram is labeled J.122\_FE-1.
+
+Figure E.1 – Spanning tree topology
+
+The task for the public spanning tree protocol, with reference to Figure E.1, is to:
+
+- Isolate the private bridged networks from each other. If the two private networks merge spanning trees then each is subject to instabilities in the other's network. Also, the combined tree may exceed the maximum allowable bridging diameter.
+- Isolate the public network from the private networks' spanning trees. The public network must not be subject to instabilities induced by customers' networks; nor should it change the spanning tree characteristics of the customers' networks.
+- Disable one of the two redundant links into the cable network, so as to prevent forwarding loops. This should occur at the cable modem, rather than at an arbitrary bridge within the customer's network.
+
+The spanning tree protocol must also serve the topology illustrated in Figure E.2:
+
+![Figure E.2: Spanning tree across CMTSs. The diagram shows a 'Switched/Bridged Headend Network' on the left connected to two 'CMTS (bridge)' units. Each CMTS is connected to a 'Cable Modem', which in turn is connected to a 'Bridged Private Network' on the right. A link labeled 'Link-X' connects the headend network to the top CMTS. A label 'J.122_E-2' is present in the bottom right corner of the diagram area.](fb0319c4dcc4ab3fe727d783a67a355a_img.jpg)
+
+Figure E.2: Spanning tree across CMTSs. The diagram shows a 'Switched/Bridged Headend Network' on the left connected to two 'CMTS (bridge)' units. Each CMTS is connected to a 'Cable Modem', which in turn is connected to a 'Bridged Private Network' on the right. A link labeled 'Link-X' connects the headend network to the top CMTS. A label 'J.122\_E-2' is present in the bottom right corner of the diagram area.
+
+**Figure E.2 – Spanning tree across CMTSs**
+
+In Figure E.2, in normal operation, the spanning tree protocol should deactivate a link at one of the two cable modems. It should not divert traffic across the private network. Note that in some circumstances, such as deactivation of link-X, spanning tree will divert traffic onto the private network (although limits on learned MAC addresses will probably throttle most transit traffic). If this diversion is undesirable, then it must be prevented by means external to spanning tree; for example, by using routers.
+
+### **E.3 Public spanning tree protocol details**
+
+The data-over-cable spanning tree algorithm and protocol is identical to that defined in [b-ISO/IEC 10038], with the following exceptions:
+
+- When transmitting configuration bridge protocol data units (BPDUs), the data-over-cable spanning tree multicast address 01-E0-2F-00-00-03 MUST be used rather than that defined in IEEE 802.1D. These BPDUs will be forwarded rather than recalculated by ordinary IEEE 802.1D bridges.
+- When transmitting configuration BPDUs, the SNAP header AA-AA-03-00-E0-2F-73-74 MUST be used rather than the LLC 42-42-03 header employed by IEEE 802.1D. This is to further differentiate these BPDUs from those used by IEEE 802.1D bridges, in the event that some of those bridges do not correctly identify multicast MAC addresses<sup>29</sup>.
+- IEEE 802.1D BPDUs MUST be ignored and silently discarded.
+
+<sup>29</sup> It is likely that there are a number of spanning tree bridges deployed that rely solely on the LSAPs to distinguish 802.1D packets. Such devices would not operate correctly if the data-over-cable BPDUs also used LSAP = 0x42.
+
+- Topology change notification (TCN) PDUs MUST NOT be transmitted (or processed). TCNs are used in IEEE networks to accelerate the aging of the learning database when the network topology may have changed. Since the learning mechanism within the cable network typically differs, this message is unnecessary and may result in unnecessary flooding.
+- CMTSs operating as bridges must participate in this protocol and must be assigned higher priorities (more likely to be root) than cable modems. The NSI interface on the CMTS SHOULD be assigned a port cost equivalent to a link speed of at least 100 Mbit/s. These two conditions, taken together, should ensure that:
+  - 1) a CMTS is the root; and
+  - 2) any other CMTS will use the headend network rather than a customer network to reach the root.
+- The MAC forwarder of the CMTS MUST forward BPDUs from upstream to downstream channels, whether or not the CMTS is serving as a router or a bridge.
+
+Note that CMs with this protocol enabled will transmit BPDUs onto subscriber networks in order to identify other CMs on the same subscriber network. These public spanning tree BPDUs will be carried transparently over any bridged private subscriber network. Similarly, bridging CMTSs will transmit BPDUs on the NSI as well as on the RFI interface. The multicast address and SNAP header defined above are used on all links.
+
+## E.4 Spanning tree parameters and defaults
+
+Clause 4.10.2 of [b-ISO/IEC 10038] specifies a number of recommended parameter values. Those values should be used, with the exceptions listed below:
+
+### E.4.1 Path cost
+
+In [b-ISO/IEC 10038], the following formula is used:
+
+$$\text{Path\_Cost} = 1000 / \text{Attached\_LAN\_speed\_in\_Mbit/s}$$
+
+For CMs, this formula is adapted as:
+
+$$\text{Path\_Cost} = 1000 / (\text{Upstream\_modulation\_rate} \times \text{bits\_per\_symbol\_for\_long\_data\_grant})$$
+
+That is, the modulation type (QPSK or 16QAM) for the long data grant IUC is multiplied by the raw modulation rate to determine the nominal path cost. Table E.1 provides the derived values.
+
+**Table E.1 – CM path cost**
+
+| Modulation rate | Default path cost |       |
+|-----------------|-------------------|-------|
+|                 | QPSK              | 16QAM |
+| kHz             |                   |       |
+| 160             | 3125              | 1563  |
+| 320             | 1563              | 781   |
+| 640             | 781               | 391   |
+| 1280            | 391               | 195   |
+| 2560            | 195               | 98    |
+
+For CMTSs, this formula is:
+
+$$\text{Path\_Cost} = 1000 / (\text{Downstream\_symbol\_rate} \times \text{bits\_per\_symbol})$$
+
+#### **E.4.2 Bridge priority**
+
+The bridge priority for CMs SHOULD default to 36 864 (0x9000). This is to bias the network so that the root will tend to be at the CMs. The CMs SHOULD default to 32 768, as per [b-ISO/IEC 10038].
+
+Note that both of these recommendations affect only the *default* settings. These parameters, as well as others defined in [b-ISO/IEC 10038], SHOULD be manageable throughout their entire range through the bridge MIB ([b-RFC 1493]) or other means.
+
+## Annex F
+
+### European specification additions
+
+(This annex forms an integral part of this Recommendation)
+
+This annex applies to the second technology option referred to in clause 1.1, "scope".
+
+This annex describes the physical layer specifications required for what are generally called Euro-DOCSIS cable modems. This is an optional annex and in no way affects certification of North American DOCSIS 1.x and DOCSIS 2.0 modems.
+
+The numbering of the clauses has been made so that the suffix after the F refers to the part of the specification that has changed. As a consequence, some clauses are missing in this annex because no change is required.
+
+#### F.1 Scope and purpose
+
+Refer to clause 1.
+
+#### F.2 References
+
+Refer to clause 2.
+
+#### F.3 Glossary
+
+Refer to clause 3.
+
+#### F.4 Functional assumptions
+
+This clause describes the characteristics of cable television plants to be assumed for the purpose of operating a data-over-cable system. It is not a description of CMTS or CM parameters. The data-over-cable system MUST be interoperable with the environment described in this clause.
+
+##### F.4.1 Broadband access network
+
+A coaxial-based broadband access network is assumed. This may take the form of either an all-coax or hybrid-fibre/coax (HFC) network. The generic term "cable network" is used here to cover all cases.
+
+A cable network uses a shared-medium, tree-and-branch architecture with analogue transmission. The key functional characteristics assumed in this annex are the following:
+
+- two-way transmission;
+- a maximum optical/electrical spacing between the CMTS and the most distant customer terminal of 160 km (route metres);
+- a maximum differential optical/electrical spacing between the CMTS and the closest and most distant modems of 160 km (route metres).
+
+##### F.4.2 Equipment assumptions
+
+###### F.4.2.1 Frequency plan
+
+In the downstream direction, the cable system is assumed to have a passband with a typical lower edge between 47 and 87.5 MHz and an upper edge which is implementation-dependent but is typically in the range of 300 to 862 MHz. Within that passband, PAL/SECAM analogue television signals in 7/8 MHz channels, FM-radio signals, as well as other narrow-band and wideband digital signals are assumed to be present.
+
+In the upstream direction, the cable system is assumed to have a passband with a lower edge at 5 MHz and an upper edge which is implementation-dependent but is typically in the range of 25 to 65 MHz.
+
+#### F.4.2.2 Compatibility with other services
+
+Refer to clause 4.2.2.
+
+#### F.4.2.3 Fault isolation impact on other users
+
+Refer to clause 4.2.3.
+
+#### F.4.2.4 Cable system terminal devices
+
+Compliance with EMC requirements is not covered by this Recommendation. The protection requirements with respect to electromagnetic compatibility are contained in harmonized standards published in the official journal of the European communities.
+
+Any reference in this Recommendation to the transmission of television in the forward channel that is not consistent with [b-EN 300 429] is outside the normative scope, as only [b-EN 300 429] is used for digital multi-program TV distribution by cable in European applications.
+
+Requirements for safety are outside the scope of this Recommendation. Safety standards for European applications are published by CENELEC.
+
+NOTE 1 – Examples of such CENELEC product safety standards are [b-EN 60950] and [b-EN 50083-1].
+
+NOTE 2 – For CENELEC safety categories of interfaces, see [b-EG 201 212].
+
+### F.4.3 RF channel assumptions
+
+Refer to 4.3.
+
+#### F.4.3.1 Transmission downstream
+
+The RF channel transmission characteristics of the cable network in the downstream direction, assumed for the purposes of minimal operating capability, are described in Table F.1. This assumes nominal analogue video carrier level (peak envelope power) in a 7/8 MHz channel bandwidth. All conditions are present concurrently.
+
+**Table F.1 – Assumed downstream RF channel transmission characteristics for analogue TV and sound signals**
+
+| Parameter                                                                              | Value                                                                                                                                                                                                                                                                                                                             |
+|----------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Frequency range                                                                        | Cable system normal downstream operating range is from 47 MHz to as high as 862 MHz. However, the operating range for data communication is from 108 to 862 MHz. The use of frequencies between 108 and 136 MHz may be forbidden due to national regulation with regard to interference with aeronautical navigation frequencies. |
+| RF channel spacing (design bandwidth)                                                  | 7/8 MHz. Only 8-MHz channels are used for data communication                                                                                                                                                                                                                                                                      |
+| Transit delay from headend to most distant customer                                    | $\leq 0.800$ ms (typically much less)                                                                                                                                                                                                                                                                                             |
+| Carrier-to-noise ratio in a 8 MHz band (analogue video level)                          | Not less than 44 dB (Note 4)                                                                                                                                                                                                                                                                                                      |
+| Carrier-to-interference ratio for total power (discrete and broadband ingress signals) | Not less than 52 dB within the design bandwidth                                                                                                                                                                                                                                                                                   |
+
+**Table F.1 – Assumed downstream RF channel transmission characteristics  
+for analogue TV and sound signals**
+
+| Parameter                                                                                            | Value                                                                                                                                   |
+|------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------|
+| Composite triple beat distortion for analogue modulated carriers                                     | Not greater than –57 dBc within the design bandwidth (Note 6 a)                                                                         |
+| Composite second-order distortion for analogue modulated carriers                                    | Not greater than –57 dBc within the design bandwidth (Note 6 b)                                                                         |
+| Cross-modulation level                                                                               | Under consideration                                                                                                                     |
+| Amplitude ripple (maximum)                                                                           | 2.5 dB in 8 MHz                                                                                                                         |
+| Group delay ripple in the spectrum occupied by the CMTS                                              | 100 ns over frequency range 0.5-4.43 MHz                                                                                                |
+| Micro-reflections bound for dominant echo                                                            | –10 dBc @ $\leq 0.5 \mu\text{s}$ , –15 dBc @ $\leq 1.0 \mu\text{s}$<br>–20 dBc @ $\leq 1.5 \mu\text{s}$ , –30 dBc @ $> 1.5 \mu\text{s}$ |
+| Carrier hum modulation                                                                               | Not greater than –46 dBc (0.5%)                                                                                                         |
+| Burst noise                                                                                          | Not longer than 25 $\mu\text{s}$ at a 10-Hz average rate                                                                                |
+| Seasonal and diurnal signal level variation                                                          | 8 dB                                                                                                                                    |
+| Signal level slope, 85-862 MHz                                                                       | Maximum slope of 12 dB in either the positive or negative direction                                                                     |
+| Maximum analogue video carrier level at the system outlet, inclusive of above signal level variation | 77 dB $\mu$ V (Note 6 c)                                                                                                                |
+| Lowest analogue video carrier level at the system outlet, inclusive of above signal level variation  | 60 dB $\mu$ V (Note 6 d)                                                                                                                |
+
+NOTE 1 – Transmission is from the headend combiner to the CM input at the customer location.  
+NOTE 2 – For measurements above, the normal downstream operating frequency band (except hum), impairments are referenced to the highest-frequency PAL/SECAM carrier level.  
+NOTE 3 – For hum measurements above, the normal downstream operating frequency band, a continuous-wave carrier is sent at the test frequency at the same level as the highest-frequency PAL/SECAM carrier.  
+NOTE 4 – This presumes that the average digital carrier is operated at the analogue peak carrier power level. When the digital carrier is operated below the analogue peak carrier level, this C/N may be less.  
+NOTE 5 – Measurements methods are defined in [b-EN 50083-7]  
+NOTE 6 – For SECAM systems, the following values apply:  
+a) Not greater than –52 dBc within the design bandwidth.  
+b) Not greater than –52 dBc within the design bandwidth.  
+c) 74 dB $\mu$ V.  
+d) 57 dB $\mu$ V.
+
+#### F.4.3.2 Transmission upstream
+
+The RF channel transmission characteristics of the cable network in the upstream direction, assumed for the purposes of minimal operating capability, are described in Table F.2. All conditions are present concurrently.
+
+**Table F.2 – Assumed upstream RF channel transmission characteristics**
+
+| Parameter                                                                                                                                                                   | Value                                                                                                             |
+|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------|
+| Frequency range                                                                                                                                                             | 5 up to 65 MHz edge to edge                                                                                       |
+| Transit delay from the most distant CM to the nearest CM or CMTS                                                                                                            | $\leq 0.800$ ms (typically much less)                                                                             |
+| Carrier-to-noise ratio in active channel                                                                                                                                    | Not less than 22 dB                                                                                               |
+| Carrier-to-ingress power (the sum of discrete and broadband ingress signals) ratio in active channel                                                                        | Not less than 22 dB (Note 2)                                                                                      |
+| Carrier-to-interference (the sum of noise, distortion, common-path distortion and cross-modulation) ratio in active channel                                                 | Not less than 22 dB                                                                                               |
+| Carrier hum modulation                                                                                                                                                      | Not greater than $-23$ dBc (7.0%)                                                                                 |
+| Burst noise                                                                                                                                                                 | Not longer than $10$ $\mu\text{s}$ at a 1-kHz average rate for most cases (Notes 3 and 4)                         |
+| Amplitude ripple (maximum)                                                                                                                                                  | 5-65 MHz: 2.5 dB in 2 MHz                                                                                         |
+| Group delay ripple (maximum)                                                                                                                                                | 5-65 MHz: 300 ns in 2 MHz                                                                                         |
+| Micro-reflections (maximum) single echo                                                                                                                                     | $-10$ dBc @ $\leq 0.5$ $\mu\text{s}$<br>$-20$ dBc @ $\leq 1.0$ $\mu\text{s}$<br>$-30$ dBc @ $> 1.0$ $\mu\text{s}$ |
+| Seasonal and diurnal signal level variation                                                                                                                                 | Not greater than 12 dB min. to max.                                                                               |
+| NOTE 1 – Transmission is from the CM output at the customer location to the headend.                                                                                        |                                                                                                                   |
+| NOTE 2 – Ingress avoidance or tolerance techniques MAY be used to ensure operation in the presence of time-varying discrete ingress signals that could be as high as 0 dBc. |                                                                                                                   |
+| NOTE 3 – Amplitude and frequency characteristics sufficiently strong to partially or wholly mask the data carrier.                                                          |                                                                                                                   |
+| NOTE 4 – Impulse noise levels more prevalent at lower frequencies ( $< 15$ MHz).                                                                                            |                                                                                                                   |
+
+**F.4.3.2.1 Availability**
+
+Refer to clause 4.3.2.1.
+
+**F.4.4 Transmission levels**
+
+The nominal average power level of the downstream CMTS QAM signal(s) within an 8-MHz channel is targeted to be in the range  $-13$  dBc to  $0$  dBc relative to the analogue peak video carrier level and will normally not exceed the analogue peak video carrier level (typically between  $-10$  to  $-6$  dBc for 64QAM, and between  $-6$  to  $-4$  dBc for 256QAM). The nominal power level of the upstream CM signal(s) will be as low as possible to achieve the required margin above noise and interference. Uniform power loading per unit bandwidth is commonly followed in setting upstream signal levels, with specific levels established by the cable network operator to achieve the required carrier-to-noise and carrier-to-interference ratios.
+
+**F.4.5 Frequency inversion**
+
+Refer to clause 4.5.
+
+**F.5 Communication protocols**
+
+Refer to clause 5.
+
+## **F.6 Physical media dependent sublayer specification**
+
+### **F.6.1 Scope**
+
+This clause applies to the second technology option referred to in clause 1.1, "scope". In those cases where the requirement for both technology options are identical, a reference is provided to the main text.
+
+Whenever any reference in this clause to spurious emissions conflicts with any legal requirement for the area of operation, the latter shall take precedence.
+
+### **F.6.2 Upstream**
+
+#### **F.6.2.1 Overview**
+
+Refer to clause 6.2.1.
+
+#### **F.6.2.2 Signal processing requirements**
+
+Refer to clause 6.2.2.
+
+#### **F.6.2.3 Modulation formats**
+
+Refer to clause 6.2.3.
+
+#### **F.6.2.4 R-S encode**
+
+##### **F.6.2.4.1 R-S encode modes**
+
+Refer to clause 6.2.4.1.
+
+##### **F.6.2.4.2 R-S bit-to-symbol ordering**
+
+Refer to clause 6.2.4.2.
+
+#### **F.6.2.5 R-S frame structure**
+
+Refer to clause 6.2.5.
+
+##### **F.6.2.5.1 R-S codeword length**
+
+Refer to clause 6.2.5.1.
+
+###### **F.6.2.5.1.1 Burst size**
+
+Refer to clause 6.2.5.1.1.
+
+###### **F.6.2.5.1.2 Fixed codeword length**
+
+Refer to clause 6.2.5.1.2.
+
+###### **F.6.2.5.1.3 Shortened last codeword**
+
+Refer to clause 6.2.5.1.3.
+
+##### **F.6.2.5.2 R-S FEC disabled**
+
+Refer to clause 6.2.5.2.
+
+#### **F.6.2.6 TDMA byte interleaver**
+
+Refer to clause 6.2.6.
+
+##### **F.6.2.6.1 Byte interleaver parameters**
+
+Refer to clause 6.2.6.1.
+
+### **F.6.2.6.2 Interleaver operating modes**
+
+Refer to clause 6.2.6.2.
+
+#### **F.6.2.6.2.1 Fixed mode**
+
+Refer to clause 6.2.6.2.1.
+
+#### **F.6.2.6.2.2 Dynamic mode**
+
+Refer to clause 6.2.6.2.2.
+
+##### **F.6.2.6.2.2.1 Dynamic mode calculations**
+
+Refer to clause 6.2.6.2.2.1.
+
+### **F.6.2.7 Scrambler (randomizer)**
+
+Refer to clause 6.2.7.
+
+### **F.6.2.8 TCM encoder**
+
+Refer to clause 6.2.8.
+
+#### **F.6.2.8.1 Bytes to TCM symbol mapping**
+
+Refer to clause 6.2.8.1.
+
+### **F.6.2.9 Preamble prepend**
+
+Refer to clause 6.2.9.
+
+### **F.6.2.10 Modulation rates**
+
+Refer to clause 6.2.10.
+
+### **F.6.2.11 S-CDMA framer and interleaver**
+
+Refer to clause 6.2.11.
+
+#### **F.6.2.11.1 S-CDMA framing considerations**
+
+Refer to clause 6.2.11.1.
+
+#### **F.6.2.11.2 Mini-slot numbering**
+
+Refer to clause 6.2.11.2.
+
+##### **F.6.2.11.2.1 Mini-slot numbering parameters in UCD**
+
+Refer to clause 6.2.11.2.1.
+
+##### **F.6.2.11.2.2 Mini-slot numbering examples**
+
+Refer to clause 6.2.11.2.2.
+
+#### **F.6.2.11.3 Transmission time**
+
+Refer to clause 6.2.11.3.
+
+#### **F.6.2.11.4 Latency considerations**
+
+Refer to clause 6.2.11.4.
+
+#### **F.6.2.11.5 Spreader-off bursts for maintenance on S-CDMA channel**
+
+Refer to clause 6.2.11.5.
+
+#### **F.6.2.11.6 Limiting the number of codes assigned to a CM**
+
+Refer to clause 6.2.11.6.
+
+#### **F.6.2.12 S-CDMA framer**
+
+Refer to clause 6.2.12.
+
+##### **F.6.2.12.1 Subframe definition**
+
+Refer to clause 6.2.12.1.
+
+##### **F.6.2.12.2 Framer operation**
+
+Refer to clause 6.2.12.2.
+
+###### **F.6.2.12.2.1 Rules for preamble and coded TCM symbols**
+
+Refer to clause 6.2.12.2.1.
+
+###### **F.6.2.12.2.2 Rules for uncoded symbols and the uncoded TCM subsymbols**
+
+Refer to clause 6.2.12.2.2.
+
+###### **F.6.2.12.2.3 Subframe example**
+
+Refer to clause 6.2.12.2.3.
+
+###### **F.6.2.12.2.4 Frame transmission**
+
+Refer to clause 6.2.12.2.4.
+
+#### **F.6.2.13 Symbol mapping**
+
+Refer to clause 6.2.13.
+
+#### **F.6.2.14 S-CDMA spreader**
+
+Refer to clause 6.2.14.
+
+##### **F.6.2.14.1 Code hopping**
+
+Refer to clause 6.2.14.1.
+
+#### **F.6.2.15 Transmit pre-equalizer**
+
+Refer to clause 6.2.15.
+
+#### **F.6.2.16 Spectral shaping**
+
+Refer to clause 6.2.16.
+
+##### **F.6.2.16.1 Upstream frequency agility and range**
+
+The upstream PMD sublayer MUST support operation over the frequency range of 5-65 MHz edge to edge.
+
+Offset frequency resolution MUST be supported, having a range of  $\pm 32$  kHz (increment = 1 Hz; implement within  $\pm 10$  Hz).
+
+##### **F.6.2.16.2 Spectrum format**
+
+Refer to clause 6.2.16.2.
+
+#### **F.6.2.17 Relative processing delays**
+
+Refer to clause 6.2.17.
+
+#### F.6.2.18 Transmit power requirements
+
+The CM MUST support varying the amount of transmit power. Requirements are presented for:
+
+- 1) range of reported transmit power;
+- 2) step size of power commands;
+- 3) step size accuracy (actual change in output power compared to commanded change); and
+- 4) absolute accuracy of CM output power.
+
+The protocol by which power adjustments are performed is defined in clause 11.2.4. Such adjustments by the CM MUST be within the ranges of tolerances described below. A CM MUST confirm that the transmit power limits are met after a RNG-RSP is received or after a UCD change.
+
+Transmit power is defined as the average RF power in the occupied bandwidth (channel width) transmitted in the data symbols of a burst, assuming equally likely QAM symbols, measured at the F-connector of the CM.
+
+Maximum and minimum transmit power level requirements refer to the CM's target transmit power level, defined as the CM's estimate of its actual transmit power. The actual transmitted power MUST be within  $\pm 2$  dB of the target power. The target transmit power MUST be variable over the range specified in Table F.5.
+
+Transmit power as reported by the CM in the MIB is referenced to the 64QAM constellation. When transmitting with other constellations, a slightly different transmit power will result, depending on the constellation gain in Table F.3 (see clause 6.2.13). As an example, if the reported power is 90 dB $\mu$ V, 64QAM will be transmitted with a target power of 90 dB $\mu$ V, while QPSK will be transmitted with 88.82 dB $\mu$ V.
+
+**Table F.3 – Constellation gains and power limits**
+
+| Constellation | Constellation Gain $G_{const}$ relative to 64QAM (dB) | $P_{min}$ (dB $\mu$ V) | $P_{max}$ (dB $\mu$ V) TDMA | $P_{max}$ (dB $\mu$ V) S-CDMA | $P_{min} - G_{const}$ (dB $\mu$ V) | $P_{max} - G_{const}$ (dB $\mu$ V) TDMA | $P_{max} - G_{const}$ (dB $\mu$ V) S-CDMA |
+|---------------|-------------------------------------------------------|------------------------|-----------------------------|-------------------------------|------------------------------------|-----------------------------------------|-------------------------------------------|
+| QPSK          | -1.18                                                 | 68                     | 118                         | 113                           | 69.18                              | 119.18                                  | 114.18                                    |
+| 8QAM          | -0.21                                                 | 68                     | 115                         | 113                           | 68.21                              | 115.21                                  | 113.21                                    |
+| 16QAM         | -0.21                                                 | 68                     | 115                         | 113                           | 68.21                              | 115.21                                  | 113.21                                    |
+| 32QAM         | 0.00                                                  | 68                     | 114                         | 113                           | 68.00                              | 114.00                                  | 113.00                                    |
+| 64QAM         | 0.00                                                  | 68                     | 114                         | 113                           | 68.00                              | 114.00                                  | 113.00                                    |
+| 128QAM        | 0.05                                                  | 68                     | N/A                         | 113                           | 67.95                              | N/A                                     | 112.95                                    |
+
+The actual transmitted power within a burst MUST be constant to within 0.1 dB peak to peak. This excludes the amplitude variation theoretically present due to QAM amplitude modulation, pulse shaping, pre-equalization and for S-CDMA, spreading and varying number of allocated codes.
+
+The CM MUST support the transmit power calculations defined in clauses F.6.2.18.1 and F.6.2.18.2
+
+##### F.6.2.18.1 TDMA transmit power calculations
+
+In TDMA mode, the CM determines its target transmit power  $P_t$  as follows. Define:
+
+$P_r$  = Reported power level (dB $\mu$ V) of CM in MIB (refers to 64QAM constellation)
+
+$\Delta P$  = Power level adjustment (dB); for example, as commanded in ranging response message
+
+$G_{const}$  = Constellation gain (dB) relative to 64QAM constellation (see Table F.3)
+
+|           |   |                                                                                              |
+|-----------|---|----------------------------------------------------------------------------------------------|
+| $P_{min}$ | = | Minimum target transmit power permitted for the CM per clause 6.2.21.1 (see Table F.3)       |
+| $P_{max}$ | = | Maximum target transmit power permitted for the CM per clause 6.2.21.1 (see Table F.3)       |
+| $P_{hi}$  | = | $\min(P_{max} - G_{const})$ over all burst profiles used by the CM (see Table F.3)           |
+| $P_{low}$ | = | $\max(P_{min} - G_{const})$ over all burst profiles used by the CM (see Table F.3)           |
+| $P_t$     | = | Target transmit power level (dB $\mu$ V) of CM (actual transmitted power as estimated by CM) |
+
+The CM updates its reported power by the following steps:
+
+- 1)  $P_r = P_r + \Delta P$  //Add power level adjustment to reported power level
+- 2)  $P_r = \min[P_r, P_{hi}]$  //Clip at max power limit
+- 3)  $P_r = \max[P_r, P_{low}]$  //Clip at min power limit
+
+The CM then transmits with target power  $P_t = P_r + G_{const}$ , i.e., the reported power plus the constellation gain.
+
+Usually the reported power level is a relatively constant quantity, while the transmitted power level varies dynamically as different burst profiles, with different constellation gains, are transmitted. A CM's target transmit power MUST never be below  $P_{min}$  or above  $P_{max}$ . This implies that, in some cases, the extreme transmit power levels (e.g., 118 dB $\mu$ V for QPSK and 68 dB $\mu$ V) may not be permitted if burst profiles with multiple constellations are active. Also, if only QPSK is used, the reported power may be greater than 118 dB $\mu$ V, although the target transmit power will not exceed 118 dB $\mu$ V.
+
+For example, if only QPSK and 64QAM burst profiles are active,  $P_{hi} = 114$  dB $\mu$ V and  $P_{low} = 69.2$  dB $\mu$ V. The maximum permitted QPSK transmitted power is  $114 - 1.2 = 112.8$  dB $\mu$ V, the minimum QPSK power is  $69.2 - 1.2 = 68$  dB $\mu$ V, the maximum 64QAM power is 114 dB $\mu$ V, and the minimum 64QAM power is 69.2 dB $\mu$ V.
+
+## F.6.2.18.2 S-CDMA transmit power calculations
+
+Refer to clause 6.2.18.2.
+
+### F.6.2.18.2.1 S-CDMA transmit power calculations with maximum scheduled codes not enabled
+
+In S-CDMA mode, when maximum scheduled codes is not enabled, the CM determines its target transmit power  $P_t$  as follows. Define:
+
+|           |   |                                                                                                                                                                                          |
+|-----------|---|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| $P_r$     | = | reported power level (dBmV) of CM in MIB (refers to 64QAM constellation and all active codes transmitted)                                                                                |
+| $P_{hi}$  | = | $\min[P_{max} - G_{const}]$ over all burst profiles used by the CM (see Table F.3)                                                                                                       |
+| $P_{low}$ | = | $\max[P_{min} - G_{const}] + 10 \log(\text{number\_active\_codes}/\text{number\_of\_codes\_per\_mini-slot})$ where the maximum is over all burst profiles used by the CM (see Table F.3) |
+
+The CM updates its reported power by the following steps:
+
+- 1)  $P_r = P_r + \Delta P$  //Add power level adjustment to reported power level
+- 2)  $P_r = \min[P_r, P_{hi}]$  //Clip at max power limit
+- 3)  $P_r = \max[P_r, P_{low}]$  //Clip at min power limit
+
+In a spreader-on frame, the CM then transmits each code  $i$  with target power:
+
+$$P_{t,i} = P_r + G_{const,i} - 10 \log(\text{number\_active\_codes})$$
+
+i.e., the reported power plus the constellation gain  $G_{const,i}$  of that code, less a factor taking into account the number of active codes. The total transmit power  $P_t$  in a frame is the sum of the individual transmit powers  $P_{t,i}$  of each code, where the sum is performed using absolute power quantities (non-dB domain).
+
+In a spreader-off frame, the CM target transmit power is  $P_t = P_r + G_{const}$ .
+
+The transmitted power level varies dynamically as the number of allocated codes varies, and as different burst profiles, with different constellation gains, are transmitted. A CM's target transmit power MUST never be below  $P_{min}$  or above  $P_{max}$ , including over all numbers of allocated codes and all burst profiles. This implies that in some cases the extreme transmit power levels (e.g., 68 and 113 dB $\mu$ V) may not be permitted. Also if, for example, only QPSK is used, the reported power may be greater than 113 dB $\mu$ V, although the target transmit power will not exceed 113 dB $\mu$ V.
+
+If, for example, QPSK and 64QAM burst profiles are active, the number of active codes is 128 and the number of codes per mini-slot is 2, then  $P_{hi} = 113$  dB $\mu$ V and  $P_{low} = 87.24$  dB $\mu$ V. The maximum permitted QPSK transmitted power is  $113 - 1.18 = 111.82$  dB $\mu$ V when all active codes are transmitted, the minimum QPSK power is  $87.24 - 1.18 - 10\log(128) + 10\log(2) = 68$  dB $\mu$ V when one mini-slot is transmitted. The last term in the sum is the result of summing the individual powers over 2 codes. Similarly, the maximum 64QAM power is 113 dB $\mu$ V when all active codes are transmitted, and the minimum 64QAM power is  $87.24 - 10\log(128) + 10\log(2) = 69.18$  dB $\mu$ V with one mini-slot transmitted. The minimum QPSK power permitted while transmitting, for example, 2 mini-slots is 71 dB $\mu$ V, and the minimum 64QAM power permitted while transmitting 2 mini-slots is 72.2 dB $\mu$ V.
+
+The CM needs to implement some form of clipping on the transmitted waveform at the higher output powers in order to prevent peak to average ratio (PAR) issues.
+
+The power received at the CMTS in a spreader-on frame will sometimes be less than the nominal power of a spreader-off frame because of such factors as:
+
+- 1) broadcast opportunities not used by any CM;
+- 2) unicast grants not used by one or more CMs; or
+- 3) mini-slots assigned to the NULL SID.
+
+#### F.6.2.18.2.2 S-CDMA transmit power calculations with maximum scheduled codes enabled
+
+In S-CDMA mode on channels on which maximum scheduled codes is enabled, the CM determines its target transmit power  $P_t$  as follows. Define:
+
+$$\begin{aligned}
+ P_r &= \text{reported power level (dBmV) of CM in MIB (operational transmit power of the spreader-off ranging burst referenced to 64QAM modulation)} \\
+ P_{hi\_S} &= \min[113 - G_{const}] \text{ over all spreader-on burst profiles used by the CM (see Table F.3)} \\
+ P_{low\_S} &= \max[68 - G_{const}] + 10 \log(\text{number\_active\_codes} / \text{number\_of\_codes\_per\_mini-slot}) \text{ where the maximum is over all burst profiles used by the CM (see Table F.3)} \\
+ P_{max\_T} &= \text{maximum target transmit power permitted for the CM in TDMA mode (see Table F.3) for the constellation used in ranging.} \\
+ P_{hi\_T} &= \min[P_{max\_T} - G_{const}] \text{ over all spreader-off burst profiles used by the CM (see Table F.3)} \\
+ P_{on} &= P_r \text{ clipped at the maximum spreader-on limit} \\
+ P_{sf} &= \text{CM power shortfall} \\
+ P_{hr} &= \text{S-CDMA power headroom} \\
+ \Delta P &= \text{power level adjustment in dB sent from CMTS to CM}
+ \end{aligned}$$
+
+The CM updates its reported power by the following steps:
+
+- 1)  $P_r = P_r + \Delta P$  //Add power level adjustment to reported power level
+- 2)  $P_r = \min[P_r, P_{hi\_T}]$  //Clip at max TDMA power limit
+- 3)  $P_r = \max[P_r, P_{low\_S}]$  //Clip at min S-CDMA power limit
+- 4)  $P_{on} = \min[P_r, P_{hi\_S}]$  //Clip at max S-CDMA power limit
+
+In spreader-off frames, the CM transmits with target power
+
+$$P_t = P_r + G_{const}$$
+
+Based on the spreader-off transmit power, the CM updates its power shortfall according to the following steps:
+
+- 1)  $P_{sf} = P_r + \max[G_{const,i}] - 113$  //Difference between spreader-off reported and max spreader-on target powers
+- 2)  $P_{sf} = \max[P_{sf}, 0]$  //Set  $P_{sf}$  to 0 if  $P_t$  is less than 113 dB $\mu$ V
+
+In spreader-on frames, the CM transmits each code i with target power
+
+$$P_{t,i} = P_{on} + G_{const,i} - 10 \log(\text{number\_active\_codes}) + P_{hr}$$
+
+i.e., the clipped reported power plus the constellation gain  $G_{const,i}$  of that code, less a factor taking into account the number of active codes, plus the power headroom  $P_{hr}$ .  $P_{hr}$  is the power (in dB) added to account for CMs that have a maximum scheduled codes limit and can transmit additional power per code. The total transmit power  $P_t$  in a frame is the sum of the individual transmit powers  $P_{t,i}$  of each code, where the sum is performed over all  $N_{alloc}$  allocated codes using absolute power quantities (non-dB domain).
+
+$$P_t = 10 \log \sum_{i=1}^{N_{alloc}} 10^{P_{t,i}/10}$$
+
+If, for example, the burst profile contains QPSK for IUCs 1, 2, 3 and 4 and 64QAM for IUCs 9 and 10, the number of active codes is 128, and the number of codes per mini-slot is 2, then  $P_{hi\_S} = 113$  dB $\mu$ V,  $P_{low\_S} = 87.24$  dB $\mu$ V, and  $P_{hi\_T} = 118$  dB $\mu$ V. Assume the CM ranges at spreader-off target transmit power of 117 dB $\mu$ V. The CM reports  $P_{sf} = 117$  dB $\mu$ V - 113 dB $\mu$ V = 4 dB. The CMTS uses  $P_{sf}$  to set (using its vendor-specific algorithm)  $\text{max\_scheduled\_codes} = 32$  and  $P_{hr} = 6$  dB (the S-CDMA power headroom may differ from the power shortfall, at the discretion of the CMTS). The CM sets its transmitted power per code to:
+
+$$\begin{aligned} P_{ti} &= P_{on} + G_{const,i} - 10 \log(\text{number\_active\_codes}) + P_{hr} \\ &= 113 \text{ dB}\mu\text{V} + 0 \text{ dB} - 21 \text{ dB} + 6 \text{ dB} \quad \text{//For a code with 64QAM modulation} \\ &= 98 \text{ dB}\mu\text{V} \end{aligned}$$
+
+A parameter that may be used to illustrate the effect of increased power per code is the effective transmit power,  $P_{eff}$ , the power that would result hypothetically if all  $N_{act}$  active codes were transmitted. It is computed as:
+
+$$\begin{aligned} P_{eff} &= 10 \log \sum_{i=1}^{N_{act}} 10^{P_{t,i}/10} \\ &= P_{on} + P_{hr} + 10 \log \frac{1}{N_{act}} \sum_{i=1}^{N_{act}} 10^{G_{const,i}/10} \end{aligned}$$
+
+where the last term is the average constellation gain.
+
+For a reference case with all codes transmitted using 64QAM modulation ( $G_{const} = 0$  dB), the effective transmit power reduces to:
+
+$$P_{eff} = P_{on} + P_{hr}$$
+
+Continuing the above example, the result is:
+
+$$\begin{aligned} P_{eff} &= 113 \text{ dB}\mu\text{V} + 6 \text{ dB} \\ &= 119 \text{ dB}\mu\text{V} \end{aligned}$$
+
+Limiting the number of codes has given the CM an enhanced effective power of 119 dB $\mu$ V, which is 6 dB above the normal maximum of 113 dB $\mu$ V, and 2 dB above the ranging power of 117 dB $\mu$ V. In this example, the CMTS used its discretion to ask for 2 dB more enhancement than was needed ( $P_{hr} = 6$  dB vs  $P_{sf} = 4$  dB), perhaps due to some known impairment in the channel.
+
+The effective SNR is an SNR estimate for a given code corresponding to the effective transmit power. It is defined as the measured SNR at the last station maintenance, minus the CM power shortfall, plus the power headroom, plus the difference in constellation gain between the ranging burst and the code under consideration. Its equation is:
+
+$$effective\_SNR = measured\_SNR - P_{sf} + P_{hr} + (G_{const, i} - G_{const, ranging})$$
+
+where  $G_{const, ranging}$  is the constellation gain of the ranging burst that resulted in the SNR measurement. In the MIB, *effective\_SNR* corresponds to a reference case with 64QAM modulation ( $G_{const, i} = 0$  dB):
+
+$$effective\_SNR = measured\_SNR - P_{sf} + P_{hr} - G_{const, ranging}$$
+
+Continuing the example, if the measured SNR in the last station maintenance was 17 dB using QPSK modulation ( $G_{const, ranging} = -1.18$  dB), then the effective SNR referenced to 64QAM modulation is:
+
+$$effective\_SNR = 17 \text{ dB} - 4 \text{ dB} + 6 \text{ dB} + 1.18 \text{ dB} = 20.18 \text{ dB}$$
+
+### F.6.2.18.3 Transmit power step size
+
+The step resolution in transmit power MUST be 1 dB or less. When a CM is commanded with finer resolution than it can implement, it MUST round to the nearest supported step size. If the commanded step is halfway between two supported step sizes, the CM MUST choose the smaller step. For example, with a supported step resolution of 1 dB, a command to step  $\pm 0.5$  dB would result in no step, while a command to step  $\pm 0.75$  dB would result in a  $\pm 1$  dB step.
+
+The step size accuracy MUST be within  $\pm 0.4$  dB. For example, the actual power increase resulting from a command to increase the power level by 1 dB in a CM's next transmitted burst MUST be between 0.6 dB and 1.4 dB.
+
+A relaxation in step size accuracy to  $\pm 1.4$  dB is allowed for one gain change when changing the power throughout the full power control range in either direction (from low-end to high-end power and vice versa). The locations of these two gain changes with relaxed accuracy MUST be at least 2 dB apart, thus enabling the use of large step attenuators in the coverage of the full power control range (hysteresis effect).
+
+### F.6.2.19 Burst profiles
+
+The transmission characteristics are separated into three portions:
+
+- a) channel parameters;
+- b) burst profile attributes; and
+- c) user-unique parameters.
+
+The channel parameters include:
+
+- i) the modulation rate (six rates from 160 ksymb/s to 5.12 Msymb/s in octave steps);
+- ii) the centre frequency (Hz);
+- iii) the 1536-bit preamble superstring; and
+- iv) the S-CDMA channel parameters.
+
+The channel parameters are further described in Table 8-18; these characteristics are shared by all users on a given channel. The burst profile attributes are listed in Table F.4 and are further described in Table 8-19; these parameters are the shared attributes corresponding to a burst type. The user-unique parameters may vary for each user even when using the same burst type on the same channel as another user (for example, power level), and are listed in Table F.5.
+
+**Table F.4 – Burst profile attributes**
+
+| Burst profile attributes                                             | Configuration settings                                                               |
+|----------------------------------------------------------------------|--------------------------------------------------------------------------------------|
+| Modulation                                                           | QPSK, 8QAM, 16QAM, 32QAM, 64QAM, 128QAM (TCM only)                                   |
+| Differential encoding                                                | On/off                                                                               |
+| TCM encoding                                                         | On/off                                                                               |
+| Preamble length                                                      | 0-1536 bits (see clause F.6.2.9)                                                     |
+| Preamble value offset                                                | 0 to 1534                                                                            |
+| R-S FEC error correction (T)                                         | 0 to 16 (0 implies no R-S FEC. The number of codeword parity bytes is $2 \times T$ ) |
+| R-S FEC codeword information bytes (k)                               | Fixed: 16 to 253 (assuming R-S FEC on)<br>Shortened: 16 to 253 (assuming R-S FEC on) |
+| Scrambler seed                                                       | 15 bits                                                                              |
+| Maximum burst length (mini-slots) <sup>a)</sup>                      | 0 to 255                                                                             |
+| Guard time                                                           | 4 to 255 modulation intervals<br>There is no guard time in S-CDMA                    |
+| Last codeword length                                                 | Fixed, shortened                                                                     |
+| Scrambler on/off                                                     | On/off                                                                               |
+| Interleaver width ( $N_r$ ) (R-S codeword length, $k + 2 \times T$ ) | 18 to 255                                                                            |
+| Byte interleaver depth ( $I_r$ ) <sup>b)</sup>                       | 0 to floor $(2048/N_r)^{c)}$                                                         |
+| Byte interleaver block size ( $B_r$ ) <sup>d)</sup>                  | $2 \times N_r$ to 2048                                                               |
+| Interleaver packet size ( $N_f$ ), (in bytes, including FEC)         | $\geq 18$ bytes                                                                      |
+| Preamble type                                                        | QPSK0/QPSK1                                                                          |
+| S-CDMA spreader <sup>e)</sup>                                        | On/off                                                                               |
+| S-CDMA codes per subframe <sup>e)</sup>                              | 1 to 128                                                                             |
+
+**Table F.4 – Burst profile attributes**
+
+| Burst profile attributes                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Configuration settings                   |
+|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------|
+| S-CDMA interleaver step <sup>e)</sup>                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | 1 to (spreading intervals per frame – 1) |
+| <sup>a)</sup> A burst length of 0 mini-slots in the channel profile means that the burst length is variable on that channel for that burst type. The burst length, while not fixed, is granted explicitly by the CMTS to the CM in the MAP.<br><sup>b)</sup> If depth = 1, no interleaving; if depth = 0, dynamic mode.<br><sup>c)</sup> $N_r$ is the R-S codeword size $k + 2T$ as defined in clause F.6.2.1.<br><sup>d)</sup> Used only in dynamic mode.<br><sup>e)</sup> Used only for S-CDMA channels. |                                          |
+
+**Table F.5 – User-unique burst parameters**
+
+| User-unique parameter                                                            | Adjustment command                                                                                                                                                                                                                                                       |                                                                                                                                                                                                               |
+|----------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Power level                                                                      | 8-bit two's complement, resolution = 0.25 dB                                                                                                                                                                                                                             | TDMA:<br>+68 to +114 dB $\mu$ V (32QAM, 64QAM)<br>+68 to +115 dB $\mu$ V (8QAM, 16QAM)<br>+68 to +118 dB $\mu$ V (QPSK)<br>S-CDMA:<br>+68 to +113 dB $\mu$ V (all modulations)<br>Resolution + 1 dB or better |
+| Offset frequency (Note)                                                          | Range = $\pm 32$ kHz, resolution = 1 Hz                                                                                                                                                                                                                                  | Frequency range per clause F.6.2.16.1 frequency agility and range                                                                                                                                             |
+| Ranging offset                                                                   | Integer part: 32-bit two's complement, resolution = $(1/10.24 \text{ MHz}) = 6.25 \text{ } \mu\text{s}/64 = 97.65625 \text{ ns}$<br>Fractional part: unsigned 8-bit fractional extension, resolution = $6.25 \text{ } \mu\text{s}/(64*256) = 0.3814697265625 \text{ ns}$ | Range: sufficient for maximum cable plant length per clause F.4.1, broadband access network<br>Resolution: TDMA $6.25 \mu\text{s}/64$ . S-CDMA: $6.25 \mu\text{s}/(64*256)$                                   |
+| Burst Length (mini-slots) if variable on this channel (changes burst-to-burst)   | N/A                                                                                                                                                                                                                                                                      | 1 to 255 mini-slots                                                                                                                                                                                           |
+| Transmit equalizer coefficients<br>(See clause F.6.2.15, transmit pre-equalizer) | DOCSIS 2.0 mode: 24 complex coefficients, 4 bytes per coefficient (2 real and 2 imaginary), load and convolve modes<br>DOCSIS 1.1 mode: up to 64 complex coefficients, 4 bytes per coefficient (2 real and 2 imaginary), convolve mode only                              | DOCSIS 2.0 mode: 24 complex coefficients<br>DOCSIS 1.1 mode: up to 64 complex coefficients                                                                                                                    |
+
+The CM MUST generate each burst at the appropriate time as conveyed in the mini-slot grants provided by the CMTS MAPs (see clause 8.3.4).
+
+The CM MUST support all burst profiles commanded by the CMTS via the burst descriptors in the UCD (see clause 8.3.3), and subsequently assigned for transmission in a MAP (see clause 8.3.4).
+
+#### **F.6.2.19.1 Ranging offset**
+
+Ranging offset is the time difference between the CM upstream frame time base and the CMTS upstream frame time base. It is an advancement equal to roughly the round-trip delay between the CM and the CMTS, and is needed to synchronize upstream transmissions in the TDMA and S-CDMA schemes. The CMTS MUST provide the CM with feedback adjustments of this offset, based on reception of one or more successfully received bursts (i.e., satisfactory result from each technique employed: error correction and/or CRC). The CMTS sends these timing adjust commands to the CM in the ranging response MAC message, where a negative value implies the ranging offset is to be decreased, resulting in later times of transmission at the CM.
+
+For TDMA channels, the CM MUST implement the timing adjust command with resolution of at most 1 symbol duration (of the symbol rate in use for a given burst), and (other than a fixed bias) with accuracy within  $\pm 0.25 \mu\text{s}$  plus  $\pm 1/2$  symbol owing to resolution. As an example, for the maximum symbol rate of 5.12 Msymb/s, the corresponding symbol period would be 195 ns, the corresponding maximum resolution for the timing adjust MUST be 195 ns, and the corresponding minimum accuracy MUST be  $\pm 348 \text{ ns}$ . The accuracy of CM burst timing of  $\pm 0.25 \mu\text{s}$  plus  $\pm 1/2$  symbol is relative to the mini-slot boundaries derivable at the CM based on an ideal processing of the timestamp signals received from the CMTS.
+
+The resolution of the integer part of the timing adjust parameter, which is used for TDMA channels, is  $(1/10.24 \text{ MHz}) = 6.25 \mu\text{s}/64 \approx 97.66 \text{ ns}$ . For S-CDMA channels, the CMTS provides an additional fractional field in the timing adjust command, with resolution of  $1/16384$  of the frame tick increment  $= 6.25 \mu\text{s}/(64*256) \approx 0.3814 \text{ ns}$ .
+
+For S-CDMA channels, the CM MUST implement the timing adjust to within  $\pm 0.01$  of the nominal chip period. As an example, for the maximum chip rate of 5.12 Mchips/s, the corresponding maximum resolution for implementation of the timing correction would be  $(\pm 0.01)*195 \text{ ns}$  or roughly  $\pm 2 \text{ ns}$ .
+
+#### **F.6.2.19.2 TDMA reconfiguration times**
+
+Refer to clause 6.2.19.2.
+
+#### **F.6.2.19.3 S-CDMA reconfiguration times**
+
+Refer to clause 6.2.19.3.
+
+#### **F.6.2.19.4 CM timing offsets when changing modulation rate**
+
+Refer to clause 6.2.19.4.
+
+#### **F.6.2.20 Burst timing convention**
+
+Refer to clause 6.2.20.
+
+#### **F.6.2.21 Fidelity requirements**
+
+The following requirements assume that any pre-equalization is disabled unless otherwise noted.
+
+##### **F.6.2.21.1 Spurious emissions**
+
+The spurious emissions specifications are separated into two regions based on the transmit power. Region 1 is defined to have a power range of  $+74 \text{ dB}\mu\text{V}$  to  $(P_{max} - 3)$ , i.e., the central region. Region 2 is defined from  $+68 \text{ dB}\mu\text{V}$  to  $+74 \text{ dB}\mu\text{V}$  and  $(P_{max} - 3)$  to  $P_{max}$ , i.e., the low and high ends of the transmit power.  $P_{max}$  depends on the modulation order, per Table F.5, as follows: for TDMA,  $+118 \text{ dB}\mu\text{V}$  for QPSK,  $+115 \text{ dB}\mu\text{V}$  for 8QAM/16QAM,  $+114 \text{ dB}\mu\text{V}$  for 32QAM/64QAM, and  $+113 \text{ dB}\mu\text{V}$  for all modulations of S-CDMA.
+
+For S-CDMA mode, when a modem is transmitting fewer than 4 spreading codes, the region 2 specifications are used for all transmit power levels. Otherwise, for all other numbers of spreading codes (e.g., 4 to 128) or for TDMA mode, the spurious emissions specifications are used according to the power ranges defined for regions 1 and 2 above.
+
+In addition, for S-CDMA, the spurious emission specifications for S-CDMA MUST be met for any *number\_allocated\_codes*, as defined in clause F.6.2.19.
+
+The noise and spurious power MUST NOT exceed the levels given in Tables F.6, F.7 and F.8.
+
+**Table F.6 – Spurious emissions**
+
+| Parameter                                                                                                                                          | Transmitting Burst                                                                                                                            | Between Bursts                                                     |
+|----------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------|
+| Inband                                                                                                                                             | –40 dBc                                                                                                                                       | The greater of –72 dBc or +1 dBμV                                  |
+| Adjacent band                                                                                                                                      | See Table F.7                                                                                                                                 | The greater of –72 dBc or +1 dBμV                                  |
+| 3 or fewer carrier-related frequency bands (such as second harmonic, if <65 MHz)                                                                   | Region 1: –50 dBc for transmitted modulation rate = 320 kHz and above; –47 dBc for transmitted modulation rate = 160 kHz<br>Region 2: –47 dBc | The greater of –72 dBc or +1 dBμV                                  |
+| Bands within 5 to 65 MHz (excluding assigned channel, adjacent channels and carrier-related channels)                                              | See Table F.8                                                                                                                                 | The greater of –72 dBc or +1 dBμV                                  |
+| CM integrated spurious emissions limits (all in 250 kHz, includes discretes)<br>87.5 to 108 MHz                                                    | 30 dBμV                                                                                                                                       | 1 dBμV                                                             |
+| CM integrated spurious emissions limits (all in 4.75 MHz, includes discretes <sup>a)</sup> )<br>65 to 87.5 MHz<br>108 to 136 MHz<br>136 to 862 MHz | max –40 dBc, 34 dBμV<br>20 dBμV<br>15 dBμV                                                                                                    | 34 dBμV<br>15 dBμV<br>max (15 dBμV, –40 dB ref d/s <sup>b)</sup> ) |
+| CM discrete spurious emissions limits <sup>c)</sup> )<br>65 to 87.5 MHz<br>108 to 862 MHz                                                          | max –50 dBc, 24 dBμV<br>10 dBμV                                                                                                               | 24 dBμV<br>10 dBμV                                                 |
+
+<sup>a)</sup> The frequencies from 108 to 136 MHz may be forbidden due to national regulations.
+
+<sup>b)</sup> "dB ref d/s" is relative to the received downstream signal level. Some spurious outputs are proportional to the receive signal level.
+
+<sup>c)</sup> These specification limits exclude a single discrete spur related to the tuned received channel; this single discrete spur MUST NOT be greater than 20 dBμV.
+
+**Table F.7 – Adjacent channel spurious emissions relative to the transmitted burst power level**
+
+| Transmitted carrier modulation rate | Specification in the interval, region 1 | Specification in the interval, region 2 | Measurement interval and distance from carrier edge | Adjacent channel carrier modulation rate |
+|-------------------------------------|-----------------------------------------|-----------------------------------------|-----------------------------------------------------|------------------------------------------|
+| All modulation rates                | –47 dBc                                 | –45 dBc                                 | 20 kHz to 180 kHz                                   | 160 ksymb/s                              |
+|                                     | –47 dBc                                 | –45 dBc                                 | 40 kHz to 360 kHz                                   | 320 ksymb/s                              |
+|                                     | –46 dBc                                 | –45 dBc                                 | 80 kHz to 720 kHz                                   | 640 ksymb/s                              |
+|                                     | –45 dBc                                 | –44 dBc                                 | 160 kHz to 1440 kHz                                 | 1280 ksymb/s                             |
+|                                     | –44 dBc                                 | –41 dBc                                 | 320 kHz to 2880 kHz                                 | 2560 ksymb/s                             |
+|                                     | –42 dBc                                 | –38 dBc                                 | 640 kHz to 5760 kHz                                 | 5120 ksymb/s                             |
+
+**Table F.8 – Spurious emissions in 5 to 65 MHz relative to the transmitted burst power level**
+
+| Possible modulation rate in this interval | Specification in the interval, region 1 | Specification in the interval, region 2 | Initial measurement interval and distance from carrier edge |
+|-------------------------------------------|-----------------------------------------|-----------------------------------------|-------------------------------------------------------------|
+| 160 ksymb/s                               | –54 dBc                                 | –53 dBc                                 | 220 kHz to 380 kHz                                          |
+| 320 ksymb/s                               | –52 dBc                                 | –50 dBc                                 | 240 kHz to 560 kHz                                          |
+| 640 ksymb/s                               | –50 dBc                                 | –47 dBc                                 | 280 kHz to 920 kHz                                          |
+| 1280 ksymb/s                              | –48 dBc                                 | –44 dBc                                 | 360 kHz to 1640 kHz                                         |
+| 2560 ksymb/s                              | –46 dBc                                 | –41 dBc                                 | 520 kHz to 3080 kHz                                         |
+| 5120 ksymb/s                              | –44 dBc                                 | –38 dBc                                 | 840 kHz to 5960 kHz                                         |
+
+In Table F.6, inband spurious includes noise, carrier leakage, clock lines, synthesizer spurious products and other undesired transmitter products. It does not include ISI. The measurement bandwidth for inband spurious is equal to the modulation rate (e.g., 160 to 5120 kHz). All requirements expressed in dBc are relative to the actual transmit power that the CM emits.
+
+The measurement bandwidth for the three (or fewer) carrier-related frequency bands (below 65 MHz) is 160 kHz, with up to three 160 kHz bands, each with no more than the value given in Table F.6, allowed to be excluded from the bands within 5 to 65 MHz transmitting burst specifications of Table F.8. Carrier-related spurious emissions include all products whose frequency is a function of the carrier frequency of the upstream transmission such as, but not limited to, carrier harmonics.
+
+The measurement bandwidth is also 160 kHz for the between bursts specifications of Table F.6 below 65 MHz.
+
+The transmitting burst specifications apply during the mini-slots granted to the CM (when the CM uses all or a portion of the grant) and for 32 modulation intervals before and after the granted mini-slots. The between bursts specifications apply except during a used grant of mini-slots, and the 32 modulation intervals before and after the used grant.
+
+In TDMA mode, a mini-slot may be as short as 32 modulation intervals, or 6.25 microseconds at the 5.12 Msymb/s rate, or as short as 200 microseconds at the 160 ksymb/s rate.
+
+These specification limits exclude three or fewer discrete spurs. Such spurs must not be greater than 20 dB $\mu$ V.
+
+#### F.6.2.21.1.1 Adjacent channel spurious emissions
+
+Spurious emissions from a transmitted carrier may occur in an adjacent channel that could be occupied by a carrier of the same or different modulation rate. Table F.7 lists the required adjacent channel spurious emission levels for all combinations of transmitted carrier modulation rates and adjacent channel modulation rates. The measurement is performed in an adjacent channel interval that is of appropriate bandwidth and distance from the transmitted carrier based on the modulation rates of the transmitted carrier and the carrier in the adjacent channel.
+
+#### F.6.2.21.1.2 Spurious emissions in 5 to 65 MHz
+
+Spurious emissions, other than those in an adjacent channel or carrier-related emissions listed above, may occur in intervals (frequency bands) that could be occupied by other carriers of the same or different modulation rates. To accommodate these different modulation rates and associated bandwidths, the spurious emissions are measured in an interval equal to the bandwidth corresponding to the modulation rate of the carrier that could be transmitted in that interval. This interval is independent of the current transmitted modulation rate.
+
+Table F.8 lists the possible modulation rates that could be transmitted in an interval, the required spurious level in that interval, and the initial measurement interval at which to start measuring the spurious emissions. Measurements should start at the initial distance and be repeated at increasing distance from the carrier until the upstream band edge, 5 MHz or 65 MHz, is reached. Measurement intervals should not include the three or fewer carrier related emission bands excluded above.
+
+#### F.6.2.21.2 Spurious emissions during burst on/off transients
+
+Each transmitter MUST control spurious emissions, prior to and during ramp-up and during and following ramp-down, before and after a burst.
+
+On/off spurious emissions, such as the change in voltage at the upstream transmitter output due to enabling or disabling transmission, MUST be no more than 100 mV, and such a step MUST be dissipated no faster than 2  $\mu\text{s}$  of constant slewing. This requirement applies when the CM is transmitting at +115 dB $\mu\text{V}$  or more; at backed-off transmit levels, the maximum change in voltage MUST decrease by a factor of 2 for each 6-dB decrease of power level from +115 dB $\mu\text{V}$ , down to a maximum change of 7 mV at +91 dB $\mu\text{V}$  and below. This requirement does not apply to CM power-on and power-off transients.
+
+#### F.6.2.21.3 Modulation error ratio (MER)
+
+Refer to clause 6.2.21.3.
+
+##### F.6.2.21.3.1 Definitions
+
+Refer to clause 6.2.21.3.1.
+
+##### F.6.2.21.3.2 Requirements
+
+Unless otherwise stated, the MER MUST meet or exceed the following limits over the full transmit power range of Table 6-8 for each modulation, each modulation rate, and over the full carrier frequency range, and for S-CDMA, over any valid number of active and allocated codes. The 5-65 MHz carrier frequency range refers more precisely to  $[5 \text{ MHz} + \text{modulation rate} \times 1.25/2]$  to  $[65 \text{ MHz} - \text{modulation rate} \times 1.25/2]$ . At the break points between regions, the higher MER specification applies.
+
+##### Case 1: Flat channel, transmit equalization OFF
+
+Case 1a: For modulation rates 2.56 MHz and below:
+
+$\text{MER}_{\text{symb}} \geq 30 \text{ dB}$  over 15 to 47 MHz carrier frequency
+
+$\text{MER}_{\text{symb}} \geq 27 \text{ dB}$  over 10 to 15 MHz and 47 to 54 MHz carrier frequency
+
+$\text{MER}_{\text{symb}} \geq 23 \text{ dB}$  over 5 to 10 MHz and 54 to 65 MHz carrier frequency
+
+Case 1b: For modulation rate 5.12 MHz:
+
+$\text{MER}_{\text{symb}} \geq 27 \text{ dB}$  over 15 to 47 MHz carrier frequency
+
+$\text{MER}_{\text{symb}} \geq 24 \text{ dB}$  over 10 to 15 MHz and 47 to 54 MHz carrier frequency
+
+$\text{MER}_{\text{symb}} \geq 20 \text{ dB}$  over 5 to 10 MHz and 54 to 65 MHz carrier frequency
+
+### **Case 2: Flat channel, transmit equalization ON**
+
+Case 2a: For TDMA/QPSK,  $\text{MER}_{\text{symb}} \geq 30 \text{ dB}$ .
+
+Case 2b: For S-CDMA and all TDMA modulations except QPSK,  $\text{MER}_{\text{symb}} \geq 35 \text{ dB}$ .
+
+Case 2c: For S-CDMA,  $\text{MER}_{\text{chip}} \geq 33 \text{ dB}$ .
+
+### **Case 3: Echo channel, transmit equalization ON**
+
+Case 3a: In the presence of a single echo selected from the channel micro-reflections defined in Table 4-2, the measured  $\text{MER}_{\text{symb}}$  MUST be  $\geq 33 \text{ dB}$  for TDMA/QPSK, and  $\geq 33 \text{ dB}$  for S-CDMA and all TDMA modulations except QPSK.
+
+Case 3b: In the presence of two or three of the echoes defined in Table 4-2 (at most one of each specified magnitude and delay), the measured  $\text{MER}_{\text{symb}}$  MUST be  $\geq 29 \text{ dB}$ .
+
+Since the table does not bound echo delay for the  $-30 \text{ dBc}$  case, for testing purposes it is assumed that the time span of the echo at this magnitude is less than or equal to  $1.5 \text{ }\mu\text{s}$ .
+
+The CMTS MUST provide a test mode in which it:
+
+- Accepts equalizer coefficients via an external interface, e.g., Ethernet.
+- Sends the coefficients to the CM's pre-equalizer via ranging response message (both set and convolve modes).
+- Does not adjust the CM's frequency, timing or power.
+
+#### **F.6.2.21.4 Filter distortion**
+
+Refer to clause 6.2.21.4.
+
+##### **F.6.2.21.4.1 Amplitude**
+
+Refer to clause 6.2.21.4.1.
+
+##### **F.6.2.21.4.2 Phase**
+
+Refer to clause 6.2.21.4.2.
+
+#### **F.6.2.21.5 Carrier phase noise**
+
+Refer to clause 6.2.21.5.
+
+#### **F.6.2.21.6 Channel frequency accuracy**
+
+Refer to clause 6.2.21.6.
+
+#### **F.6.2.21.7 Modulation rate accuracy**
+
+Refer to clause 6.2.21.7.
+
+#### **F.6.2.21.8 Modulation timing jitter**
+
+##### **F.6.2.21.8.1 Symbol timing jitter for asynchronous operation**
+
+Refer to clause 6.2.21.8.1.
+
+#### F.6.2.21.8.2 Chip timing jitter for synchronous operation
+
+All jitter specifications assume a downstream input to the CM per clauses F.6.3.5, F.6.3.6, F.6.3.7.2, F.6.3.7.3, F.6.3.9 and F.6.3.10.
+
+For S-CDMA mode, upstream chip clock timing error (with the mean error subtracted out) relative to the CM-CTS master clock MUST be less than 0.005 RMS of the chip period over a 35-second measurement interval. This applies:
+
+- 1) to the worst-case jitter and frequency drift specified for the CM-CTS master clock and the CM-CTS downstream symbol clock in the requirements above; and
+- 2) for any round-trip propagation delay up to the maximum allowed.
+
+The CM upstream chip clock SHOULD track the jitter components below 10 Hz in the input downstream symbol clock with an error transfer function below -25 dB. The CM upstream chip clock SHOULD attenuate the jitter components in the input downstream symbol clock above 200 Hz.
+
+The CM MUST provide a test mode in which:
+
+- A continuous (non-bursted) upstream signal is transmitted at the commanded carrier frequency, modulation rate and level.
+- The chip sequence at the spreader output is replaced with an alternating binary sequence (1, -1, 1, -1, 1, -1, ...) at nominal amplitude, equal on both I and Q.
+- The CM tracks the downstream symbol clock and uses it to generate upstream symbol clock as in normal synchronous operation.
+
+#### F.6.2.22 Upstream demodulator input power characteristics
+
+The maximum total input power to the upstream demodulator MUST NOT exceed 95 dB $\mu$ V in the 5-65 MHz frequency range of operation.
+
+The intended received power in each carrier MUST be within the values shown in Table F.9.
+
+**Table F.9 – Maximum range of commanded nominal receive power in each carrier**
+
+| Modulation rate (ksymb/s) | Maximum range (dB $\mu$ V) |
+|---------------------------|----------------------------|
+| 160                       | +44 to +74                 |
+| 320                       | +47 to +77                 |
+| 640                       | +50 to +80                 |
+| 1280                      | +53 to +83                 |
+| 2560                      | +56 to +86                 |
+| 5120                      | +59 to +89                 |
+
+The demodulator MUST operate within its defined performance specifications with received bursts within  $\pm 6$  dB of the nominal commanded received power.
+
+#### F.6.2.23 Upstream electrical output from the CM
+
+The CM MUST output an RF modulated signal with the characteristics delineated in Table F.10.
+
+**Table F.10 – Electrical output from CM**
+
+| Parameter                 | Value                                                                                                                                                                                    |
+|---------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Frequency                 | 5 to 65 MHz edge to edge                                                                                                                                                                 |
+| Level range (one channel) | TDMA:<br>+68 to +114 dB $\mu$ V (32QAM, 64QAM)<br>+68 to +115 dB $\mu$ V (8QAM, 16QAM)<br>+68 to +118 dB $\mu$ V (QPSK)<br>S-CDMA:<br>+68 to +113 dB $\mu$ V (all modulations of S-CDMA) |
+| Modulation type           | QPSK, 8QAM, 16QAM, 32QAM, 64QAM and 128QAM                                                                                                                                               |
+| Modulation rate (nominal) | TDMA: 160, 320, 640, 1280, 2560 and 5120 ksymb/s<br>S-CDMA: 1280, 2560 and 5120 ksymb/s                                                                                                  |
+| Channel bandwidth         | TDMA: 200, 400, 800, 1600, 3200 and 6400 kHz<br>S-CDMA: 1600, 3200 and 6400 kHz                                                                                                          |
+| Nominal output impedance  | 75 ohms                                                                                                                                                                                  |
+| Output return loss        | >6 dB (5-65 MHz)                                                                                                                                                                         |
+| Connector                 | F connector per [IEC 60169-24] (common with the input)                                                                                                                                   |
+
+### F.6.3 Downstream
+
+This DOCSIS 2.0 downstream specification applies only to a CMTS supporting exactly one QAM channel per RF output port. A CMTS supporting more than one QAM channel per RF output port would instead conform to the European technology option of the DOCSIS downstream radio frequency interface as specified in Annex A of [DOCS9] in lieu of this clause.
+
+#### F.6.3.1 Downstream protocol
+
+The downstream PMD sublayer MUST conform to [b-EN 300 429].
+
+#### F.6.3.2 Interleaving
+
+The downstream PMD sublayer MUST support the interleaver with the characteristics defined in Table F.11. This interleaver mode fully complies with [b-EN 300 429].
+
+**Table F.11 – Interleaver characteristics**
+
+| I<br>(number of taps) | J<br>(increment) | Burst protection<br>64QAM/256QAM | Latency<br>64QAM/256QAM |
+|-----------------------|------------------|----------------------------------|-------------------------|
+| 12                    | 17               | 18 $\mu$ s/14 $\mu$ s            | 0.43 ms/0.32 ms         |
+
+#### F.6.3.3 Downstream frequency plan
+
+The downstream frequency plan will include all centre frequencies between 112 and 858 MHz on 250 kHz increments. It is up to the operator to decide which frequencies to use to meet national and network requirements.
+
+#### F.6.3.4 CMTS electrical output
+
+The CMTS MUST output an RF modulated signal with the following characteristics defined in Table F.12.
+
+**Table F.12 – CMTS output**
+
+| Parameter                                                              | Value                                                                                                                                                                                                                                     |
+|------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Centre frequency ( $f_c$ )                                             | 112 to 858 MHz $\pm$ 30 kHz                                                                                                                                                                                                               |
+| Level                                                                  | Adjustable over the range 110 to 121 dB $\mu$ V                                                                                                                                                                                           |
+| Modulation type                                                        | 64QAM and 256QAM                                                                                                                                                                                                                          |
+| Symbol rate (nominal)<br>64QAM<br>256QAM                               | 6.952 Msymb/s<br>6.952 Msymb/s                                                                                                                                                                                                            |
+| Nominal channel spacing                                                | 8 MHz                                                                                                                                                                                                                                     |
+| Frequency response<br>64QAM<br>256QAM                                  | $\sim$ 0.15 square root raised cosine shaping<br>$\sim$ 0.15 square root raised cosine shaping                                                                                                                                            |
+| Total discrete spurious inband<br>( $f_c \pm 4$ MHz)                   | $< -57$ dBc                                                                                                                                                                                                                               |
+| Inband spurious and noise<br>( $f_c \pm 4$ MHz)                        | $< -46.7$ dBc; where channel spurious and noise includes all discrete spurious, noise, carrier leakage, clock lines, synthesizer products and other undesired transmitter products. Noise within $\pm 50$ kHz of the carrier is excluded. |
+| Adjacent channel<br>( $f_c \pm 4.0$ MHz)<br>to ( $f_c \pm 4.75$ MHz)   | $< -58$ dBc in 750 kHz                                                                                                                                                                                                                    |
+| Adjacent channel<br>( $f_c \pm 4.75$ MHz)<br>to ( $f_c \pm 12$ MHz)    | $< -60.6$ dBc in 7.25 MHz, excluding up to three spurs, each of which must be $< -60$ dBc when each is measured with 10 kHz bandwidth.                                                                                                    |
+| Next adjacent channel<br>( $f_c \pm 12$ MHz)<br>to ( $f_c \pm 20$ MHz) | Less than the greater of $-63.7$ dBc or $49.3$ dB $\mu$ V in 8 MHz, excluding up to three discrete spurs. The total power in the spurs must be $< -60$ dBc when each is measured with 10 kHz bandwidth.                                   |
+| Other channels<br>(80 MHz to 1000 MHz)                                 | $< 49.3$ dB $\mu$ V in each 8-MHz channel, excluding up to three discrete spurs. The total power in the spurs must be $< -60$ dBc when each is measured with 10 kHz bandwidth.                                                            |
+| Phase noise                                                            | 1 kHz-10 kHz: $-33$ dBc double-sided noise power<br>10 kHz-50 kHz: $-51$ dBc double-sided noise power<br>50 kHz-3 MHz: $-51$ dBc double-sided noise power                                                                                 |
+| Output impedance                                                       | 75 ohms                                                                                                                                                                                                                                   |
+| Output return loss                                                     | $> 14$ dB within an output channel up to 750 MHz; $> 13$ dB in an output channel above 750 MHz                                                                                                                                            |
+| Connector                                                              | F connector per [IEC 60169-24]                                                                                                                                                                                                            |
+
+### F.6.3.5 Downstream electrical input to CM
+
+The CM MUST accept an RF modulated signal with the following characteristics (see Table F.13).
+
+**Table F.13 – Electrical input to CM**
+
+| Parameter                      | Value                                                                                                                          |
+|--------------------------------|--------------------------------------------------------------------------------------------------------------------------------|
+| Centre frequency               | 112 to 858 MHz $\pm$ 30 kHz                                                                                                    |
+| Level range (one channel)      | 43 to 73 dB $\mu$ V for 64QAM<br>47 to 77 dB $\mu$ V for 256QAM                                                                |
+| Modulation type                | 64QAM and 256QAM                                                                                                               |
+| Symbol rate (nominal)          | 6.952 Msymb/s (64QAM) and 6.952 Msymb/s (256QAM)                                                                               |
+| Bandwidth                      | 8 MHz (alpha = 0.15 square root raised cosine shaping for 64QAM and alpha = 0.15 square root raised cosine shaping for 256QAM) |
+| Total input power (80-862 MHz) | <90 dB $\mu$ V                                                                                                                 |
+| Input (load) impedance         | 75 ohms                                                                                                                        |
+| Input return loss              | >6 dB (85 to 862 MHz)                                                                                                          |
+| Connector                      | F connector per [IEC 60169-24] (common with the output)                                                                        |
+
+### F.6.3.6 CM BER performance
+
+The bit-error-rate performance of a CM MUST be as described in this clause. The requirements apply to the I = 12, J = 17 mode of interleaving.
+
+#### F.6.3.6.1 64QAM
+
+##### F.6.3.6.1.1 64QAM CM BER performance
+
+Implementation loss of the CM MUST be such that the CM achieves a post-FEC BER less than or equal to  $10^{-8}$  when operating at a carrier to noise ratio ( $E_s/N_0$ ) of 25.5 dB or greater.
+
+##### F.6.3.6.1.2 64QAM image rejection performance
+
+Performance as described in clause F.6.3.6.1.1 MUST be met with an analogue or digital signal at +10 dBc in any portion of the RF band other than the adjacent channels.
+
+##### F.6.3.6.1.3 64QAM adjacent channel performance
+
+Performance as described in clause F.6.3.6.1.1 MUST be met with a digital signal at 0 dBc in the adjacent channels.
+
+Performance as described in clause F.6.3.6.1.1 MUST be met with an analogue signal at 10 dBc in the adjacent channels.
+
+Performance as described in clause F.6.3.6.1.1, with an additional 0.2-dB allowance, MUST be met with a digital signal at +10 dBc in the adjacent channels.
+
+#### F.6.3.6.2 256QAM
+
+##### F.6.3.6.2.1 256QAM CM BER performance
+
+Implementation loss of the CM MUST be that the CM achieves a post-FEC BER less than or equal to  $10^{-8}$  when operating at a carrier to noise ratio ( $E_s/N_0$ ) as shown in Table F.14.
+
+**Table F.14 – 256QAM CM BER performance**
+
+| <b>Input receive signal level</b> | <b><math>E_s/N_0</math></b> |
+|-----------------------------------|-----------------------------|
+| 47 dB $\mu$ V to 54 dB $\mu$ V    | 34.5 dB                     |
+| >54 to +77 dB $\mu$ V             | 31.5 dB                     |
+
+**F.6.3.6.2.2 256QAM image rejection performance**
+
+Performance as described in clause F.6.3.6.2.1 MUST be met with an analogue or digital signal at +10 dBc in any portion of the RF band other than the adjacent channels.
+
+**F.6.3.6.2.3 256QAM adjacent channel performance**
+
+Performance as described in clause F.6.3.6.2.1 MUST be met with an analogue or digital signal at 0 dBc in the adjacent channels.
+
+Performance as described in clause F.6.3.6.2.1, with an additional 0.5-dB allowance, MUST be met with an analogue signal at +10 dBc in the adjacent channels.
+
+Performance as described in clause F.6.3.6.2.1, with an additional 1.0-dB allowance, MUST be met with a digital signal at +10 dBc in the adjacent channels.
+
+**F.6.3.6.2.4 Additional specifications for QAM**
+
+The following additional specifications are given for the QAM modulation.
+
+| <b>Parameter</b>        | <b>Specification</b> |
+|-------------------------|----------------------|
+| I/Q phase offset        | <1.0°                |
+| I/Q crosstalk           | –50 dB               |
+| I/Q amplitude imbalance | 0.05 dB max          |
+| I/Q timing skew         | <3.0 ns              |
+
+**F.6.3.7 CMTS timestamp jitter**
+
+Refer to clause 6.3.7.
+
+**F.6.3.7.1 CMTS master clock jitter for asynchronous operation**
+
+Refer to clause 6.3.7.1.
+
+**F.6.3.7.2 CMTS master clock jitter for synchronous operation**
+
+Refer to clause 6.3.7.2.
+
+**F.6.3.7.3 CMTS master clock frequency drift for synchronous operation**
+
+Refer to clause 6.3.7.3.
+
+**F.6.3.8 CMTS clock generation**
+
+The CMTS has the following three options related to the synchronization of the CMTS master clock and the downstream symbol clock:
+
+- 1) Not locked.
+- 2) Downstream symbol clock locked to CMTS master clock.
+- 3) CMTS master clock locked to downstream symbol clock.
+
+For S-CDMA operation, the master clock and the downstream symbol clock MUST be locked using either option 2 or 3.
+
+Let  $f_b'$  represent the rate of the downstream symbol clock, which is locked to the CMTS master clock, and let  $f_m'$  represent the rate of the CMTS master clock locked to the downstream symbol clock. Let  $f_b$  represent the nominal specified downstream symbol rate and let  $f_m$  represent the nominal CMTS master clock rate (10.24 MHz).
+
+With the downstream symbol clock locked to the CMTS master clock, the following equation MUST hold:
+
+$$f_b' = f_m \times M/N$$
+
+With the CMTS master clock locked to the downstream symbol clock, the following equation MUST hold:
+
+$$f_m' = f_b \times N/M$$
+
+M and N MUST be unsigned integer values, each capable of being represented in 16 bits. (These are specified in the channel TLV parameters of the UCD). When the downstream symbol clock and the CMTS master clock are not locked together (sync mode = 0), the values of M and N are not valid and are ignored by the CM.
+
+The values of M and N MUST result in a value of  $f_b'$  or  $f_m'$ , which is not more than  $\pm 1$  ppm from its specified nominal value. Table F.15 lists the downstream modes of operation, their associated nominal symbol rates,  $f_b$ , example values for M and N, the resulting synchronized clock rates, and their offsets from their nominal values.
+
+**Table F.15 – Downstream symbol rates and example parameters for synchronization with the CMTS master clock**
+
+| Downstream mode                   | Nominal specified symbol rate, $f_b$ (MHz) | M/N      | CMTS master clock rate, $f_m'$ (MHz) | Downstream symbol rate, $f_b'$ (MHz) | Offset from nominal |
+|-----------------------------------|--------------------------------------------|----------|--------------------------------------|--------------------------------------|---------------------|
+| Annex A, 64QAM and 256QAM (8 MHz) | 6.952                                      | 869/1280 | 10.24                                | 6.952                                | 0 ppm               |
+
+### F.6.3.9 Downstream symbol clock jitter for synchronous operation
+
+The downstream symbol clock MUST meet the following double sideband phase noise requirements over the following frequency ranges:
+
+- $< [-50 + 20 \times \log(f_{DS}/6.952)]$  dBc (i.e.,  $< 0.07$  ns RMS) 10 Hz to 100 Hz
+- $< [-50 + 20 \times \log(f_{DS}/6.952)]$  dBc (i.e.,  $< 0.07$  ns RMS) 100 Hz to 1 kHz
+- $< [-50 + 20 \times \log(f_{DS}/6.952)]$  dBc (i.e.,  $< 0.07$  ns RMS) 1 kHz to 10 kHz
+- $< [-33 + 20 \times \log(f_{DS}/6.952)]$  dBc (i.e.,  $< 0.5$  ns RMS) 10 kHz to 100 kHz
+- $< [-27 + 20 \times \log(f_{DS}/6.952)]$  dBc (i.e.,  $< 1$  ns RMS) 100 kHz to ( $f_{DS}/2$ )
+
+where  $f_{DS}$  is the frequency of the measured clock in MHz. The value of  $f_{DS}$  MUST be an integral multiple or divisor of the downstream symbol clock. For example, an  $f_{DS} = 27.808$ -MHz clock may be measured if there is no explicit 6.952 MHz clock available.
+
+The CMTS MUST provide a test mode in which:
+
+- the downstream QAM symbol sequence is replaced with an alternating binary sequence (1, -1, 1, -1, 1, -1, ...) at nominal amplitude, on both I and Q;
+- the CMTS generates the downstream symbol clock from the 10.24-MHz reference clock as in normal synchronous operation.
+
+If an explicit downstream symbol clock that is capable of meeting the above phase noise requirements is available (e.g., a smooth clock without clock domain jitter), this test mode is not required.
+
+#### F.6.3.10 Downstream symbol clock drift for synchronous operation
+
+Refer to clause 6.3.10.
+
+### F.7 Downstream transmission convergence sublayer
+
+#### F.7.1 Introduction
+
+Refer to clause 7.1.
+
+#### F.7.2 MPEG packet format
+
+Refer to clause 7.2.
+
+#### F.7.3 MPEG header for Euro-DOCSIS data-over-cable
+
+The format of the MPEG transport stream header is defined in clause 2.4 of [ITU-T H.222.0]. The particular field values that distinguish data-over-cable MAC streams are defined in Table F.16. Field names are from [ITU-T H.222.0].
+
+The MPEG header consists of 4 bytes that begin the 188-byte MPEG packet. The format of the header for use on an Euro-DOCSIS data-over-cable PID is restricted to that shown in Table F.16. The header format conforms to the MPEG standard, but its use is restricted in this Recommendation to NOT ALLOW inclusion of an adaptation\_field in the MPEG packets.
+
+**Table F.16 – MPEG Header format for Euro-DOCSIS data-over-cable packets**
+
+| Field                        | Length (bits) | Description                                                                                                                                                                     |
+|------------------------------|---------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| sync_byte                    | 8             | 0x47; MPEG packet sync byte                                                                                                                                                     |
+| transport_error_indicator    | 1             | Indicates an error has occurred in the reception of the packet. This bit is reset to zero by the sender, and set to one whenever an error occurs in transmission of the packet. |
+| payload_unit_start_indicator | 1             | A value of one indicates the presence of a pointer_field as the first byte of the payload (fifth byte of the packet)                                                            |
+| transport_priority           | 1             | Reserved; set to zero                                                                                                                                                           |
+| PID                          | 13            | Euro-DOCSIS data-over-cable well-known PID (0x1FFE)                                                                                                                             |
+| transport_scrambling_control | 2             | Reserved; set to '00'                                                                                                                                                           |
+| adaptation_field_control     | 2             | '01'; use of the adaptation_field is NOT ALLOWED on the Euro-DOCSIS PID                                                                                                         |
+| continuity_counter           | 4             | Cyclic counter within this PID                                                                                                                                                  |
+
+#### F.7.4 MPEG payload for Euro-DOCSIS data-over-cable
+
+The MPEG payload portion of the MPEG packet will carry the Euro-DOCSIS MAC frames. The first byte of the MPEG payload will be a 'pointer\_field' if the payload\_unit\_start\_indicator (PUSI) of the MPEG header is set.
+
+#### **F.7.4.1 stuff\_byte**
+
+This Recommendation defines a stuff\_byte pattern having a value (0xFF) that is used within the Euro-DOCSIS payload to fill any gaps between the Euro-DOCSIS MAC frames. This value is chosen as an unused value for the first byte of the Euro-DOCSIS MAC frame. The 'FC' byte of the MAC header will be defined to never contain this value (FC\_TYPE = '11' indicates a MAC-specific frame, and FC\_PARM = '11111' is not currently used and, according to this Recommendation, is defined as an illegal value for FC\_PARM).
+
+#### **F.7.4.2 pointer\_field**
+
+The pointer\_field is present as the fifth byte of the MPEG packet (first byte following the MPEG header) whenever the PUSI is set to one in the MPEG header. The interpretation of the pointer\_field is as follows.
+
+The pointer\_field contains the number of bytes in this packet that immediately follow the pointer\_field that the CM decoder must skip past before looking for the beginning of a Euro-DOCSIS MAC frame. A pointer field MUST be present if it is possible to begin a data-over-cable MAC Frame in the packet, and MUST point to either:
+
+- 1) the beginning of the first MAC frame to start in the packet; or
+- 2) any stuff\_byte preceding the MAC frame.
+
+#### **F.7.5 Interaction with the MAC sublayer**
+
+Refer to clause 7.5.
+
+#### **F.7.6 Interaction with the physical layer**
+
+The MPEG-2 packet stream MUST be encoded according to [b-EN 300 429].
+
+#### **F.7.7 MPEG header synchronization and recovery**
+
+The MPEG-2 packet stream SHOULD be declared "in frame" (i.e., correct packet alignment has been achieved) when five consecutive correct sync bytes, each 188 bytes from the previous one, have been received.
+
+The MPEG-2 packet stream SHOULD be declared "out of frame", and a search for correct packet alignment started, when nine consecutive incorrect sync bytes are received.
+
+The format of MAC frames is described in detail in clause 8.
+
+### **F.8 Media access control specification**
+
+#### **F.8.1 Introduction**
+
+Refer to clause 8.1.
+
+#### **F.8.2 MAC frame formats**
+
+Refer to clause 8.2.
+
+#### **F.8.3 MAC management messages**
+
+##### **F.8.3.1 MAC management message header**
+
+Refer to clause 8.3.1.
+
+##### **F.8.3.2 Time synchronization (SYNC)**
+
+Time synchronization (SYNC) MUST be transmitted by CMTS at a periodic interval to establish MAC sublayer timing. The message MUST use an FC field with FC\_TYPE = MAC-specific header
+
+and FC\_PARM = timing MAC header. This MUST be followed by a frame PDU in the format shown in Figure F.1.
+
+![Diagram of packet PDU format showing MAC Management Message Header and CMTS timestamp fields with bit positions 0, 8, 16, 24, 31.](7e349f38358d54134f1edb301cf18ae8_img.jpg)
+
+The diagram illustrates the structure of a packet PDU. It consists of two stacked rectangular fields. The top field is labeled 'MAC Management Message Header' and the bottom field is labeled 'CMTS timestamp'. Above the diagram, bit positions are indicated: 'Bit 0', '8', '16', '24', and '31'. The '0' is at the left edge, '8' is at the first byte boundary, '16' is at the second byte boundary, '24' is at the third byte boundary, and '31' is at the right edge of the 32-bit timestamp. There are break symbols (two wavy lines) at the left and right ends of the top field, indicating it may be longer than shown. The label 'J.122\_FF-1' is located at the bottom right of the diagram.
+
+Diagram of packet PDU format showing MAC Management Message Header and CMTS timestamp fields with bit positions 0, 8, 16, 24, 31.
+
+**Figure F.1 – Format of packet PDU following the timing header**
+
+The parameters shall be as defined below.
+
+**CMTS timestamp:** The count state of an incrementing 32-bit binary counter clocked with the CMTS 10.24-MHz master clock.
+
+The CMTS timestamp represents the count state at the instant that the first byte (or a fixed time offset from the first byte) of the time synchronization MAC management message is transferred from the downstream transmission convergence sublayer to the downstream physical media dependent sublayer as described in clause 6.3.7. A CMTS MUST always put the SYNC-message at the start of an MPEG-packet. This is required for compatibility with certain CM implementations.
+
+## Annex G
+
+### DOCS 2.0 and 1.0/1.1 interoperability
+
+(This annex forms an integral part of this Recommendation)
+
+DOCS 2.0 is the third generation of the DOCS Recommendation. The terms DOCS 2.0, DOCS 1.1, and DOCS 1.0 refer to these three different Recommendations.
+
+The DOCS 2.0 Recommendation primarily aims at enhancing the limited upstream physical layer performance of a DOCS 1.0- or 1.1-based cable access system. Two new MAC management message types have been defined, and several new parameter encodings have been defined in the existing MAC messages. A DOCS 2.0 CMTS is capable of supporting a higher upstream throughput for a given channel bandwidth as well as increased tolerance to noise experienced in the upstream.
+
+As well as supporting DOCS 2.0-capable CMs, the DOCS 2.0 CMTS must be backwards compatible with DOCS 1.0 and DOCS 1.1 CMs. Furthermore, it is necessary for a DOCS 2.0 CM to function like a 1.0 CM when interoperating with a 1.0 CMTS and to function like a 1.1 CM when interoperating with a 1.1 CMTS.
+
+This annex describes the interoperability issues and trade-offs involved when the operator wishes to support DOCS 1.0 and/or DOCS 1.1 CMs as well as DOCS 2.0 CMs on the same cable access channel.
+
+#### G.1 General interoperability issues
+
+This clause addresses the general DOCS 1.x/2.0 interoperability issues that do not depend on the modulation type used for the upstream channel.
+
+##### G.1.1 Provisioning
+
+The parameters of the TFTP configuration file for a DOCS 2.0 CM are (except for the addition of one optional TLV) identical to those for a DOCS 1.1 CM, and are a superset of those for a DOCS 1.0 CM. Configuration-file editors that support DOCS 1.1 may need to be modified to support the new TLV defined in DOCS 2.0.
+
+A TFTP configuration file containing class of service TLVs is considered a "DOCS 1.0 style" configuration file. A TFTP configuration file containing service flow TLVs is considered a "DOCS 1.1/2.0 style" configuration file. A TFTP configuration file containing both class of service and service flow TLVs will be rejected by the CMTS (see clause 11.2.9).
+
+If a DOCS 2.0 CM is provisioned with a DOCS 1.0-style TFTP configuration file, it will register as specified in clause G.1.2, although in the REG-REQ it MUST still specify "DOCS 2.0" in the DOCS version modem capability and MAY specify additional advanced (i.e., DOCS 1.1) modem capabilities that it supports. Thus, a DOCS 2.0 CM can be provisioned to work seamlessly on either a DOCS 1.0, a DOCS 1.1 or a DOCS 2.0 network. However, a DOCS 2.0 modem on a DOCS 1.x network would be clearly unable to support any DOCS 2.0-specific features.
+
+If a DOCSIS 2.0 CM operating on an S-CDMA channel with the maximum scheduled codes feature enabled (see clause 8.3.3), and provisioned with a DOCSIS 1.0-style configuration file, SHOULD support fragmentation and indicate that support in the modem capabilities encoding in the REG-REQ message. If a DOCS 2.0 CM supports certain advanced capabilities when registered as a DOCS 1.0 CM (as indicated by the modem capabilities encoding), those features MUST function according to the requirements defined in the DOCS 2.0 Recommendations.
+
+On the other hand, DOCS 1.0 CMs do not recognize (and ignore) many of the new TLVs in a DOCS 1.1/2.0 style configuration file, and will be unable to register successfully if provisioned
+
+with a DOCS 1.1/2.0 configuration file. To prevent any functionality mismatches, a DOCS 2.0 CMTS MUST reject any registration request with DOCS 1.1/2.0-specific configuration parameters that are not supported by the associated modem capabilities encoding in the REG-REQ (see clause C.1.3.1).
+
+### **G.1.2 Registration**
+
+A DOCS 2.0 CMTS is designed to handle the registration TLVs from DOCS 1.0 CMs as well as the TLVs from DOCS 1.1 (TLV types 22 to 38) or DOCS 2.0 (TLV types 22 to 39) CMs. Furthermore, a DOCS 2.0 CM can handle any TLV in a configuration file usable by a DOCS 1.0 CM.
+
+There is a slight difference in the registration-related messaging procedure when the DOCS 2.0 CMTS is responding to a DOCS 1.1 or 2.0 CM as opposed to a DOCS 1.0 CM (or a DOCS 1.1 CM using a 1.0-style configuration file). There is a further difference in the way a DOCS 2.0 CMTS handles registration from a DOCS 2.0 CM using a DOCS 1.0-style configuration file, depending on whether the upstream on which the registration is occurring has DOCS 2.0 features.
+
+A DOCS 1.1 or 2.0 CM could be configured to use the service class name, which is statically defined at the CMTS, instead of explicitly asking for the service class parameters. When the DOCS 2.0 CMTS receives such a registration request, it encodes the actual parameters of that service class in the registration response and expects the registration acknowledge MAC message from the CM. If the detailed capabilities in the registration response message exceed those the CM is capable of supporting, the CM is required to indicate this to the CMTS in its registration acknowledge.
+
+When a DOCS 1.0 CM (or a 1.1 CM using a DOCS 1.0-style configuration file) registers with the same CMTS, the absence of service class names eliminates the need for the DOCS 2.0 CMTS to explicitly specify the service class parameters in the registration response using DOCS 1.1 or 2.0 TLVs. The registration request from a DOCS 1.0 CM explicitly requests all non-default service class parameters in the registration request per its provisioning information. When a DOCS 2.0 CMTS receives a registration request containing DOCS 1.0 class of service encodings, it will respond with the DOCS 1.0-style registration response and, if the CM is a DOCS 1.x CM, not expect the CM to send the registration acknowledge MAC message. A DOCS 1.0 CM can be further identified by the absence of the "DOCS version" modem capabilities encoding in the registration request.
+
+In the case where a DOCS 2.0 CM is using a DOCS 1.0-style configuration file, there is an additional consideration. This is because in the case where the upstream is a type 2 upstream (see clause 11.2.2), and therefore supports both TDMA and A-TDMA features, the registration acknowledge message is also used to synchronize switching from TDMA (DOCS 1.x) operation to A-TDMA (DOCS 2.0) operation. It is important that this switch be coordinated correctly between the CM and the CMTS in order for the CMTS to be able to correctly interpret bandwidth requests from the CM (see clause 11.2.9). Therefore, when a DOCS 2.0 CM registers using a DOCS 1.0-style configuration file on a type 2 or type 3 upstream, it transmits a registration acknowledgment with a confirmation code of OK/SUCCESS (since DOCS 1.0-style registration does not allow for the CM to reject the registration response). The CMTS knows to expect this because the modem capabilities field in the registration request indicated that the CM was a DOCS 2.0 CM. Table G.1 summarizes registration behaviour for all cases involving a DOCS 2.0 CM.
+
+**Table G.1 – Registration behaviour for a DOCS 2.0 CM**
+
+| <b>Configuration file</b>                                                 | <b>DOCS 1.0 CMTS</b>                                                                          | <b>DOCS 2.0 CMTS with a type 1 upstream or a DOCS 1.1 CMTS</b>                                           | <b>DOCS 2.0 CMTS with a type 2 or type 3 upstream</b>                                                                                                |
+|---------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------|
+| DOCS 1.1/2.0-style configuration file that does not disable DOCS 2.0 mode | N/A                                                                                           | CM sends DOCS 1.1/2.0-style REG-REQ. CMTS sends DOCS 1.1/2.0-style REG-RSP and CM responds with REG-ACK. | CM sends DOCS 1.1/2.0-style REG-REQ. CMTS sends DOCS 1.1/2.0-style REG-RSP and CM responds with REG-ACK.                                             |
+| DOCS 1.0-style configuration file that does not disable DOCS 2.0 mode     | CM sends DOCS 1.0-style REG-REQ. CMTS sends DOCS 1.0-style REG-RSP. CM MUST NOT send REG-ACK. | CM sends DOCS 1.0-style REG-REQ. CMTS sends DOCS 1.0-style REG-RSP. CM MUST NOT send REG-ACK.            | CM sends DOCS 1.0-style REG-REQ. CMTS sends DOCS 1.0-style REG-RSP. CM MUST send REG-ACK with SUCCESS confirmation code. CMTS MUST wait for REG-ACK. |
+| DOCS 1.1/2.0-style configuration file that disables DOCS 2.0 mode         | N/A                                                                                           | CM sends DOCS 1.1/2.0-style REG-REQ. CMTS sends DOCS 1.1/2.0-style REG-RSP and CM responds with REG-ACK. | CM sends DOCS 1.1/2.0-style REG-REQ. CMTS sends DOCS 1.1/2.0-style REG-RSP and CM responds with REG-ACK.                                             |
+| DOCS 1.0-style configuration file that disables DOCS 2.0 mode             | CM sends DOCS 1.0-style REG-REQ. CMTS sends DOCS 1.0-style REG-RSP. CM MUST NOT send REG-ACK. | CM sends DOCS 1.0-style REG-REQ. CMTS sends DOCS 1.0-style REG-RSP. CM MUST NOT send REG-ACK.            | CM sends DOCS 1.0-style REG-REQ. CMTS sends DOCS 1.0-style REG-RSP. CM MUST NOT send REG-ACK.                                                        |
+
+Another minor issue is that a DOCS 1.0 CM will request a bidirectional (with upstream/downstream parameters) service class from the CMTS using a class of service configuration setting.
+
+Since a DOCS 2.0 CMTS typically operates with unidirectional service classes, it can easily translate a DOCS 1.0 class of service configuration setting into DOCS 1.1 or 2.0 service flow encodings for setting up unidirectional service classes in local QoS implementation. However, for DOCS 1.0 modems, the DOCS 2.0 CMTS MUST continue to maintain the QosProfile table (with bidirectional class parameters) for backward compatibility with the DOCS 1.0 MIB.
+
+Thus, if properly provisioned, a DOCS 1.0, a DOCS 1.1 and a DOCS 2.0 CM can all successfully register with the same DOCS 2.0 CMTS, and a DOCS 2.0 CM can register with a 1.0 CMTS. Furthermore, a DOCS 2.0 CM can use a DOCS 1.0-style configuration file, register on a DOCS 2.0 CMTS and still use DOCS 2.0 enhanced physical-layer features with DOCS 1.0 class of service features.
+
+### **G.1.3 Dynamic service establishment**
+
+There are 8 MAC messages that relate to dynamic service establishment. A DOCS 1.0 CM will never send them to any CMTS since they are unsupported. A DOCS 1.1 or 2.0 CM will never send them to a DOCS 1.0 CMTS because:
+
+- to register successfully it has to be provisioned as a DOCS 1.0 CM; and
+- when provisioned as a DOCS 1.0 CM, it acts identically.
+
+When a DOCS 1.1 or 2.0 CM is connected to a DOCS 1.1 or 2.0 CMTS, these messages work as expected.
+
+#### **G.1.4 Fragmentation**
+
+Fragmentation is initiated by the CMTS. Thus, a DOCS 1.0 CMTS will never initiate fragmentation since it knows nothing about it. A DOCS 1.1 or 2.0 CMTS can only initiate fragmentation for DOCS 1.1 or 2.0 CMs. A DOCS 1.1 or 2.0 CMTS MUST NOT attempt to fragment transmissions from a DOCS 1.0 CM that has not indicated a modem capabilities encoding for fragmentation support with a value of 1.
+
+#### **G.1.5 Multicast support**
+
+It is mandatory for DOCS 1.0 CMs to support forwarding of multicast traffic. However, the Recommendation is silent on IGMP support. The only standard mechanism for controlling IP-multicast on DOCS 1.0 CMs is through SNMP and packet filters. Designers of DOCS 1.0 networks will have to deal with these limitations and expect no different from DOCS 1.0 CMs on a DOCS 2.0 network.
+
+DOCSIS 2.0 CMs in 1.0 mode MUST still comply with the requirements for IGMP and the forwarding of multicast traffic as per clauses 5.1.2.3.2 and 5.3.1.
+
+#### **G.1.6 Changing upstream channels**
+
+A DOCS 2.0 CMTS is capable of specifying the level of re-ranging to be performed only when it issues a DCC-Request to the CM. This re-ranging technique parameter is specified by the DOCS 2.0 CMTS using a TLV in the DCC-Request MAC message.
+
+DOCS 1.1 or 2.0 CMs can benefit by only re-ranging to the level specified by this TLV. This can help in reducing the re-initialization time following a DCC for the DOCS 1.1 or 2.0 CM carrying a voice call. A DOCS 2.0 CMTS is aware of the type of CM to which it is issuing the channel change request. It MUST refrain from sending a DCC-Request for DOCS 1.0 CMs, instead choosing to send a UCC-Request. If a DOCS 2.0 CMTS sends the UCC-Request, the DOCS 1.0 CMs will perform the default DOCS 1.0 re-ranging from start (initial ranging) with its existing non-zero primary SID.
+
+### **G.2 Hybrid devices**
+
+Some DOCS 1.0 CM designs may be capable of supporting individual DOCS 1.1 features via a software upgrade. Similarly, some DOCS 1.0 CMTSs may be capable of supporting individual DOCS 1.1 features. To facilitate these "hybrid" devices, the majority of DOCS 1.1 features are individually enumerated in the modem capabilities.
+
+DOCS 1.0 hybrid CMs MAY request DOCS 1.1 features via this mechanism. However, unless a CM is fully DOCS 1.1-compliant (i.e., not a hybrid), it MUST NOT send a "DOCS version" modem capability that indicates DOCS 1.1. Similarly, unless a CM is fully DOCS 2.0-compliant, it MUST NOT send a "DOCS version" modem capability which indicates DOCS 2.0.
+
+If a hybrid CM intends to request such DOCS 1.1 capabilities from the CMTS during registration, it MUST send the ASCII coded string in option code 60 of its DHCP request, "docsis1.0:xxxxxxx", where xxxxxxx MUST be an ASCII representation of the hexadecimal encoding of the modem capabilities. Refer to clauses C.1.3.1 and D.1.1 for details. The DHCP server MAY use such information to determine what configuration file the CM is to use.
+
+In order to control the hybrid operation of modems, if a DOCS 2.0 CMTS receives a DOCS 1.0-style registration request message from a CM, the CMTS MUST, by default, force the modem to operate in a "pure" DOCS 1.0 mode with respect to certain features by disabling those features via the modem capabilities encoding in the registration response. Specifically, the CMTS MUST support the six default values given in square brackets in Table G.2. The CMTS MAY
+
+provide switches, as indicated in Table G.2, for the operator to selectively allow certain hybrid features to be enabled. As an exception to these defaults, the DOCSIS 2.0 CMTS SHOULD allow the use of fragmentation for DOCSIS 2.0 CMs registering in DOCSIS 1.0 mode on an S-CDMA channel that has the maximum scheduled codes feature (see clause 8.3.3) enabled.
+
+**Table G.2 – Hybrid mode controls**
+
+|                                     | <b>Concatenation Support</b> | <b>Fragmentation Support</b> | <b>Privacy Support</b> |
+|-------------------------------------|------------------------------|------------------------------|------------------------|
+| DOCS 1.0 CM                         | Allow/[deny]                 | Allow/[deny]                 | Allow BPI+/[force BPI] |
+| DOCS 1.1 or 2.0 CM in DOCS 1.0 mode | Allow/[deny]                 | Allow/[deny]                 | Allow BPI+/[force-BPI] |
+
+Normally, a DOCS 1.0 CMTS sets all unknown modem capabilities to "off" in the registration response indicating that these features are unsupported and MUST NOT be used by the CM. A DOCS 1.0 hybrid CMTS MAY leave supported modem capabilities set to "on" in the registration response. However, unless a CMTS is fully DOCS 1.1- or 2.0-compliant (i.e., not a hybrid), it MUST still set all "DOCS version" modem capabilities to DOCS 1.0.
+
+As always, any modem capability set to "off" in the registration response must be viewed as unsupported by the CMTS and MUST NOT be used by the CM.
+
+### **G.3 DOCS 2.0 TDMA interoperability**
+
+#### **G.3.1 Mixed-mode operation with TDMA**
+
+In mixed-mode operation with both DOCS 1.x and DOCS 2.0 TDMA, a single channel is defined with a single UCD that contains both type 4 and type 5 burst descriptors. DOCS 1.x and 2.0 modems use the type 4 burst descriptors; DOCS 2.0 modems MUST also use the type 5 burst descriptors. DOCS 2.0 modems will use IUCs 9 and 10.
+
+The following rules of operation apply:
+
+- 1) Prior to and during registration, a DOCS 2.0 TDMA-capable modem operating on a channel of type 1 or 2 (refer to clause 11.2.2) MUST calculate its request size based on DOCS 1.x IUC parameters, and the CMTS MUST make all grants using DOCS 1.x IUCs.
+- 2) On a type 2 channel, a DOCS 2.0 TDMA CM MUST switch to DOCS 2.0 TDMA mode after transmission of the registration acknowledgement (REG-ACK) message. If the CM receives a registration response (REG-RSP) message after transmission of the REG-ACK message, the CM MUST switch back to DOCS 1.1 mode before it continues with the registration process (see Figure 11-12).
+- 3) A CM in DOCS 2.0 TDMA mode MUST calculate its request size based on IUC types 9 and 10. The CMTS MUST make grants of IUC types 9 and 10 to that CM after it receives the registration acknowledgement message from the CM (see clause 11.2.9).
+- 4) On a type 2 channel, the CM MUST ignore grants with IUCs that are in conflict with its operational mode (e.g., the CM receives a grant with IUC 5 when it is in DOCS 2.0 TDMA mode).
+- 5) On a type 3 channel, the CMTS MUST use type 5 burst descriptors in order to prevent DOCS 1.x modems from attempting to use the channel. All data grants are in IUC types 9 and 10.
+- 6) On a type 2 channel, only advanced PHY short (IUC 9) and advanced PHY long (IUC 10) bursts may be classified as burst descriptor type 5.
+
+- 7) A DOCS 1.x modem that does not find appropriate type 4 burst descriptors for long or short data grant intervals MUST consider the UCD, and the associated upstream channel, unusable.
+
+### **G.3.2 Interoperability and performance**
+
+This clause addresses the issue of performance impact on the upstream channel when DOCS 1.x CMs are provisioned to share the same upstream MAC channel as DOCS 2.0 TDMA CMs.
+
+Since the initial maintenance, station maintenance, request and request/data IUCs are common to both DOCS 2.0 TDMA and DOCS 1.x CMs, the overall channel will experience reduced performance compared to a dedicated DOCS 2.0 TDMA upstream channel. This is due to broadcast/contention regions not being capable of taking advantage of improved physical layer parameters.
+
+## **G.4 DOCS 2.0 S-CDMA interoperability**
+
+### **G.4.1 Mixed-mode operation with S-CDMA**
+
+In mixed-mode operation with both TDMA and S-CDMA, two logically separate upstream channels are allocated by the CMTS, one for TDMA modems, and another for DOCS 2.0 modems operating in S-CDMA mode. Each channel has its own upstream channel ID, and its own UCD. However, these two channels are both allocated the same RF centre frequency on the same cable plant segment. The CMTS controls allocation to these two channels in such a way that the channel is shared between the two groups of modems. This can be accomplished by reserving bandwidth through the scheduling of data grants to the NULL SID on all channels other than the channel that is to contain the potential transmit opportunity. Using this method, an upstream channel can support a mixture of differing physical layer DOCS modems, with each type capitalizing on their individual strengths. The channel appears as a single physical channel that provides transmission opportunities for both DOCS 1.x and 2.0 modems. The mixed-mode configuration of the channel will be transparent to the CMs.
+
+The following rule of operation applies:
+
+- The CMTS MUST use only type 5 burst descriptors on the S-CDMA channel in order to prevent DOCS 1.x modems from attempting to use the channel.
+
+### **G.4.2 Interoperability and performance**
+
+This clause addresses the issue of performance impact on the S-CDMA upstream channel when the upstream centre frequency is shared with an upstream TDMA channel.
+
+Due to the lack of ability to share the upstream transmit opportunities, the channels will not experience the statistical multiplexing benefits during contention regions across the CMs. Dedicated initial maintenance regions will be required on both logical MAC channels slightly reducing the overall performance available. Request and request/data regions will also not be capable of being shared although an intelligent CMTS scheduler will be able to reduce most performance impact.
+
+## Annex H
+
+### The DOCS MAC/PHY interface (DMPI)
+
+(This annex forms an integral part of this Recommendation)
+
+#### H.1 Scope
+
+Integrated circuit (IC) chip sets with separate MAC and PHY chips used in the implementation of a CMTS SHOULD implement DMPI. DMPI does not apply to IC chip sets which integrate MAC and PHY components together into one chip.
+
+Any usage of "MUST", "SHOULD", or "MAY" within the DMPI specification applies only if DMPI is implemented.
+
+#### H.2 Conventions
+
+##### H.2.1 Terminology
+
+Throughout this annex, the terms "MAC" and "PHY" are used extensively. MAC is used to refer to the device which provides the interface between the PHY devices and the system. The term "PHY" refers to the device which performs the physical layer processing for a single RF channel. It is important to note that both of these terms refer to physical devices as opposed to layers in the IP protocol stack. For the purposes of this Recommendation, integrated circuit chips that handle multiple RF channels simultaneously are considered to contain multiple PHY devices.
+
+##### H.2.2 Ordering of bits and bytes
+
+The following rules control the order of transmission of bits and bytes over all the interfaces specified in this Recommendation. In all cases, fields of data blocks are transmitted in the order in which they appear in the data block format description.
+
+- Multibyte quantities are transmitted most significant byte first (big-endian byte ordering). This byte ordering applies regardless of the width of the interface (byte, nibble, single bit).
+- On nibble-wide interfaces, the most significant nibble (bits 7:4) is transmitted first.
+- On bit-wide interfaces, the most significant bit of each field is transmitted first.
+
+##### H.2.3 Signal naming conventions
+
+Signal names that end with an "\_N" are active low. Signals without this suffix are active high.
+
+##### H.2.4 Active clock edge
+
+All signals are driven and sampled on the rising edge of the clock except where otherwise noted.
+
+##### H.2.5 Timing specifications
+
+The timing specifications for DMPI use the following terminology (see Table H.1):
+
+**Table H.1 – Timing parameters**
+
+| Parameter                   | Symbol    | Description                                                                       |
+|-----------------------------|-----------|-----------------------------------------------------------------------------------|
+| Clock frequency             | $f$       | The frequency of the interface clock                                              |
+| Clock low pulse width       | $t_{lpw}$ | The low time of the interface clock                                               |
+| Clock high pulse width      | $t_{hpw}$ | The high time of the interface clock                                              |
+| Clock rise/fall time        | $t_{rf}$  | The transition time of the clock                                                  |
+| Input setup time to clock   | $t_{su}$  | From when an interface signal is valid to the following rising clock edge         |
+| Input hold time from clock  | $t_h$     | From the rising clock edge to when an interface signal becomes invalid            |
+| Clock to signal valid delay | $t_{cq}$  | From the rising edge of the interface clock to an interface signal becoming valid |
+
+Following are some usage notes for these timing parameters:
+
+- Set-up and hold time specifications are given from the point of view of the DMPI interface and not from the point of view of a device on the DMPI interface. The clock to output, on the other hand, specifies the timing requirement of a DMPI device.
+- The  $t_{su}$  parameter specifies the minimum guaranteed amount of set-up time provided by the DMPI interface measured at the receiving device. Therefore, inputs on DMPI devices should require no more than this amount of set-up time.
+- The  $t_h$  parameter specifies the minimum guaranteed amount of hold time provided by the DMPI interface measured at the receiving device. Therefore, inputs on DMPI devices should require no more than this amount of hold time.
+- The  $t_{cq}$  parameter specifies the minimum and maximum clock to output time at the driving device. The purpose of the minimum specification is to allow for clock skew between the driving and receiving DMPI device. For example, a 1-ns minimum specification and a 0-ns DMPI hold time requirement allows for at most 1-ns of clock skew between devices. The maximum specification is to allow for the settling time of signals from the driving device to the receiving device and clock skew between devices.
+
+### H.3 Overview
+
+This annex describes the DOCS MAC/PHY interface (DMPI). DMPI is used to connect a DOCS MAC device to DOCS downstream and upstream PHY devices. While DMPI is a single interface, for the purposes of clarity, DMPI signals have been grouped into four separate groups. Each group serves a specific purpose and is independent of the others. For this reason, each group of signals is also referred to as an interface.
+
+A downstream PHY MUST include a downstream data interface and an SPI bus interface. An upstream PHY must include an upstream data interface, an upstream control interface, and an SPI bus interface. PHY chips that integrate multiple PHYs into a single package MUST have one set of interfaces for each PHY that has been integrated, with the following exception:
+
+An integrated PHY device MAY use a single select and a single SPI bus for all internal PHYs (using the SPI bus protocol described in clause H.8.4). An integrated upstream PHY device MAY have only one TS\_CLK input and only one US\_CLK input.
+
+A MAC MUST include one downstream data interface for each downstream PHY it supports and one set of upstream interfaces (upstream data and upstream control) for each upstream PHY it supports. It MUST include at least one SPI bus interface.
+
+DMPI has been defined with the following goals in mind:
+
+- vendor independence;
+- flexibility for future growth and vendor differentiation;
+- minimization of PHY-specific logic in the MAC.
+
+Figure H.1 shows an example application of DMPI. Note that this figure shows the connections required for a single DS PHY and a single US PHY. Obviously, other applications with multiple DS and US PHYs are possible.
+
+![Block diagram of DMPI application showing connections between MAC, DS PHY, and US PHY blocks.](f34d4741036e8407888cd90a70d1a624_img.jpg)
+
+```
+
+graph LR
+    subgraph MAC
+        M[MAC]
+    end
+    subgraph PHYs
+        DSP[DS PHY]
+        USP[US PHY]
+    end
+
+    %% MAC to DS PHY signals
+    M -- DS_DATA[3:0] --> DSP
+    M -- DS_DATAP --> DSP
+    M -- DS_VALID_N --> DSP
+    M -- DS_MSYNC_N --> DSP
+    DSP -- DS_CLK --> M
+    DSP -- INT_N --> M
+    M -- SPI_MOSI --> DSP
+    DSP -- SPI_MISO --> M
+    M -- SPI_SS0_N --> DSP
+
+    %% MAC to US PHY signals
+    USP -- UD_DATA[3:0] --> M
+    USP -- UD_DATAP --> M
+    USP -- UD_SOB_N --> M
+    USP -- UD_DV_N --> M
+    M -- TS_FS_N --> USP
+    M -- UC_DATA --> USP
+    M -- UC_DV_N --> USP
+    USP -- UC_RDY_N --> M
+    USP -- INT_N --> M
+    M -- SPI_SS1_N --> USP
+
+    %% Shared SPI/Clock signals
+    SPI_CLK --o M
+    SPI_CLK --o DSP
+    SPI_CLK --o USP
+    TS_CLK --o M
+    TS_CLK --o USP
+    US_CLK --o M
+    US_CLK --o USP
+
+```
+
+The diagram illustrates the DMPI application interface between a MAC block and two PHY blocks: DS PHY (Downstream Physical Layer) and US PHY (Upstream Physical Layer).
+
+**MAC Block (Left):** A large vertical rectangle labeled "MAC".
+
+**DS PHY Block (Top Right):** A rectangle labeled "DS PHY". Signals between MAC and DS PHY include: DS\_DATA[3:0], DS\_DATAP, DS\_VALID\_N, DS\_MSYNC\_N (MAC to PHY); DS\_CLK, INT\_N, SPI\_MISO (PHY to MAC); SPI\_MOSI, SPI\_SS0\_N (MAC to PHY).
+
+**US PHY Block (Bottom Right):** A rectangle labeled "US PHY". Signals between MAC and US PHY include: UD\_DATA[3:0], UD\_DATAP, UD\_SOB\_N, UD\_DV\_N (PHY to MAC); TS\_FS\_N, UC\_DATA, UC\_DV\_N (MAC to PHY); UC\_RDY\_N, INT\_N (PHY to MAC); SPI\_SS1\_N (MAC to PHY).
+
+**Clock Signals:** Three external clock lines enter from the bottom left: SPI\_CLK, TS\_CLK, and US\_CLK. SPI\_CLK connects to MAC, DS PHY, and US PHY. TS\_CLK connects to MAC and US PHY. US\_CLK connects to MAC and US PHY.
+
+**Reference:** J.122\_FH-1
+
+Block diagram of DMPI application showing connections between MAC, DS PHY, and US PHY blocks.
+
+**Figure H.1 – DMPI application**
+
+### **H.3.1 Downstream data**
+
+The downstream data interface carries data from the MAC to the PHY for transmission on the downstream. All signals on the interface are synchronous with respect to a clock driven by the PHY and received by the MAC. Four bits of data are transferred on each clock. The frequency of this clock is proportional to the downstream bit rate. Its precise frequency is a function of the downstream symbol rate, the modulation type (64QAM or 256QAM), and the physical layer framing in use (see Annex A or B of [ITU-T J.83]).
+
+### **H.3.2 Upstream data**
+
+The upstream data interface carries data from the PHY to the MAC which has been received on the upstream. The interface is synchronous to a dedicated interface clock whose frequency is not directly related to the upstream bit rate.
+
+Data is transferred over the interface using a mixture of TLVs and TVs (a TLV for which the length is implied by the type). Along with the DOCS burst data, certain status information about the burst is also transferred to the MAC. There is also a TLV which allows the PHY to indicate that it did not receive a burst when one was expected.
+
+### **H.3.3 Upstream control**
+
+The upstream control interface is used for two purposes. The first is to initialize the PHY's timestamp counter, frame counter and mini-slot counter, and to check that the PHY's timestamp counter remains synchronized to the MAC's during operation. The second is to allow the MAC to pass information to the PHY regarding upcoming bursts.
+
+This interface uses two clocks. The clock used for the counter synchronization is the 10.24 MHz CMTS master clock. A single signal, that is synchronized to this clock, is used to perform this counter synchronization. The other clock used for this interface is shared with the upstream data interface and has a frequency unrelated to the upstream modulation clock or the 10.24 MHz CMTS master clock. This clock, along with an associated set of signals, is used to transfer descriptions of future bursts.
+
+### **H.3.4 SPI bus**
+
+The serial peripheral interconnect (SPI) bus is used to read and write registers in the PHYs. The system MAY use one or more SPI buses to provide register access to the PHYs. The number of SPI buses in the system is a function of the system's SPI bus performance requirements. Each SPI bus has a single master device which MAY be the MAC. Alternatively, an SPI bus master MAY be some other device in the system (e.g., a microprocessor). References to the SPI bus in this recommendation assume that the MAC is the master. The PHYs MUST only be slave devices. Each PHY MUST have one SPI bus interface. Multiple PHYs MAY share the same SPI bus.
+
+The SPI bus definition includes an interrupt signal (INT\_N). Each PHY MUST drive an interrupt. The interrupt signals MAY be received by an SPI bus master or they MAY be received by some other device in the system that provides the ability to monitor their state.
+
+## **H.4 Signals**
+
+### **H.4.1 Downstream data**
+
+The signals used for the downstream data interface are defined in Table H.2.
+
+**Table H.2 – Downstream data interface signals**
+
+| Signal       | Description                                                                                                                                                                                                                                                          |
+|--------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| DS_CLK       | DS transmit clock<br>Driven by the downstream PHY<br>See clauses H.5.1 and H.5.2 for detailed requirements for this clock                                                                                                                                            |
+| DS_MSYNC_N   | Downstream MPEG sync<br>Driven by the MAC<br>Marks first nibble of sync byte; active low                                                                                                                                                                             |
+| DS_VALID_N   | Downstream data valid<br>Driven by the MAC<br>Indicates that valid data is present on DS_DATA                                                                                                                                                                        |
+| DS_DATA[3:0] | DS transmit data<br>Driven by the MAC                                                                                                                                                                                                                                |
+| DS_DATAP     | Downstream parity<br>Driven by the MAC<br>Even parity for DS-DATA (the number of 1s across DS_DATA and DS_DATAP is even)<br>DS_DATA and its corresponding DS_DATAP are driven on the same clock.<br>Parity is not delayed a clock cycle as it is in some interfaces. |
+
+#### H.4.2 Upstream data
+
+The signals used for the upstream data interface are defined in Table H.3.
+
+**Table H.3 – Upstream data interface signals**
+
+| Signal       | Description                                                                                                                                                                                                                                                                        |
+|--------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| US_CLK       | Upstream data/control clock<br>Driven by external clock source (input to MAC and PHY)                                                                                                                                                                                              |
+| UD_SOB_N     | Upstream data start of data block<br>Driven by upstream PHY asserted when the first nibble or first byte of the data block is on UD_DATA                                                                                                                                           |
+| UD_DV_N      | Upstream data valid<br>Driven by upstream PHY indicates valid data on UD_DATA                                                                                                                                                                                                      |
+| UD_DATA[3:0] | Upstream data<br>Driven by upstream PHY                                                                                                                                                                                                                                            |
+| UD_DATAP     | Upstream data parity<br>Driven by upstream PHY<br>Even parity for UD_DATA (the number of 1s across UD_DATA and UD_DATAP is even)<br>UD_DATA and its corresponding UD_DATAP are driven on the same clock.<br>Parity is not delayed a clock cycle as it is in some other interfaces. |
+
+### H.4.3 Upstream control
+
+Table H.4 lists the signals that are used for the upstream control interface.
+
+**Table H.4 – Upstream control interface signals**
+
+| Signal   | Description                                                                                                               |
+|----------|---------------------------------------------------------------------------------------------------------------------------|
+| US_CLK   | Upstream clock<br>Driven by external clock source (input to MAC and PHY)                                                  |
+| UC_DV_N  | Upstream control data valid<br>Driven by the MAC<br>Indicates valid upstream control message data on UC_DATA              |
+| UC_DATA  | Upstream control data<br>Driven by the MAC                                                                                |
+| UC_RDY_N | Upstream control ready<br>Driven by the PHY<br>Indicates that the PHY is ready to receive an interval description message |
+| TS_CLK   | 10.24-MHz master clock<br>Driven by external clock source (input to MAC and PHY)                                          |
+| TS_FS_N  | Timestamp frame sync<br>Driven by the MAC                                                                                 |
+
+### H.4.4 SPI bus
+
+**Table H.5 – SPI bus signals**
+
+| Signal name | Description                                                                                                                                                                                                                                                                                        |
+|-------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| SPI_CLK     | SPI bus clock<br>Driven by a source external to the MAC and PHY or driven by the MAC                                                                                                                                                                                                               |
+| SPI_MOSI    | Master out/slave in<br>Serial data from the MAC to the PHY                                                                                                                                                                                                                                         |
+| SPI_MISO    | Slave out/master in<br>Serial data from the PHY to the MAC<br>MAY be driven by the PHY from the falling edge of SPI_CLK                                                                                                                                                                            |
+| SPI_SSx_N   | Slave select<br>Selects a slave for a transaction.<br>One slave select signal is provided by the MAC for each PHY (x = 1 to N).<br>Addressing of devices within a package is provided by the protocol layer described in clause H.8.4.<br>MAY be sampled by the PHY on the falling edge of SPI_CLK |
+| INT_N       | Interrupt<br>Driven by PHYs<br>Open drain                                                                                                                                                                                                                                                          |
+
+### H.4.5 Parity
+
+The downstream data, upstream data, and upstream control interfaces use parity to maintain data integrity on the interface. Parity SHOULD be implemented.
+
+The SPI bus does not have parity.
+
+Parity is even and covers only the data lines of the interface. Specific rules for parity checking are detailed in the following clauses.
+
+#### **H.4.5.1 Downstream data**
+
+Parity must be checked by the downstream PHY and covers DS\_DATA. Since the downstream transmit data is protected (DOCS frame HCS and CRC), detection of a parity error is not considered fatal and MUST NOT cause the processing of transmit data to halt. The PHY must generate an interrupt to the system when it detects a parity error so that the system can be made aware of its occurrence. Parity checking on this interface provides a way to distinguish between data errors on the interface and those in other parts of the data path.
+
+#### **H.4.5.2 Upstream data**
+
+Parity is checked by the MAC and covers UD\_DATA. Since the upstream receive data is protected (DOCS frame HCS and CRC), detection of a parity error is not considered fatal and MUST NOT cause the processing of receive data to halt. The MAC must generate an interrupt to the system when it detects a parity error so that the system can be made aware of its occurrence. Parity checking on this interface provides a way to distinguish between data errors on the interface and those in other parts of the data path.
+
+#### **H.4.5.3 Upstream control**
+
+Parity is checked by the upstream PHY and covers the entire upstream control message. A parity error on this interface is considered a fatal error. The PHY MUST NOT process the upstream control message which was received with a parity error as well as any subsequently received message. The PHY MAY process any upstream control messages received prior to the occurrence of the parity error. This processing MAY include the passage of various types of upstream data blocks to the MAC.
+
+### **H.4.6 Interrupts**
+
+Various places in this Recommendation make reference to the assertion of an interrupt by the PHY. The characteristics of this interrupt MUST be as follows:
+
+- one active low interrupt line of level type;
+- driven open drain;
+- cause of interrupt line assertion determined by software read(s) of PHY register(s) that contains one bit for each interrupt source;
+- no hardware prioritization of interrupt sources;
+- each interrupt source separately cleared by software write(s) to PHY register(s);
+- asserted until all interrupt source bits are cleared (interrupt line is a simple OR of all interrupt sources).
+
+## **H.5 Protocol**
+
+### **H.5.1 Downstream data (ITU-T Rec. J.83 Annex A)**
+
+Figure H.2 shows the protocol for ITU-T Rec. J.83 Annex A operation.
+
+![Timing diagram for Downstream data J.83 Annex A protocol. It shows five signal lines: DS_CLK (a constant frequency square wave), DS_MSYNC_N (a signal that goes low during data transfer), DS_VALID_N (a signal that goes low during data transfer), DS_DATA (a stream of data packets with fields: SYNCH, SYNCL, IH, IL, 2H, 2L, followed by a break, then 187H, 187L, then SYNCH, SYNCL), and DS_DATAP (a stream of data packets with fields: SYNCH, followed by a break, then data, then SYNCH). The diagram includes break symbols (double slashes) to indicate gaps in the timing sequence. The label J.122_FH-2 is in the bottom right corner.](228db097d546afebf934a1befb86a0a6_img.jpg)
+
+Timing diagram for Downstream data J.83 Annex A protocol. It shows five signal lines: DS\_CLK (a constant frequency square wave), DS\_MSYNC\_N (a signal that goes low during data transfer), DS\_VALID\_N (a signal that goes low during data transfer), DS\_DATA (a stream of data packets with fields: SYNCH, SYNCL, IH, IL, 2H, 2L, followed by a break, then 187H, 187L, then SYNCH, SYNCL), and DS\_DATAP (a stream of data packets with fields: SYNCH, followed by a break, then data, then SYNCH). The diagram includes break symbols (double slashes) to indicate gaps in the timing sequence. The label J.122\_FH-2 is in the bottom right corner.
+
+**Figure H.2 – Downstream data J.83 Annex A protocol**
+
+The following behaviour of DS\_CLK and DS\_VALID\_N is required:
+
+- DS\_CLK MUST NOT be gapped (it must have a constant frequency).
+- DS\_CLK frequency MUST be 1/4 of the downstream line rate. The DS line rate is the data rate including the ITU-T Rec. J.83 Annex A framing overhead.
+- The MAC MUST assert DS\_VALID\_N for the entire 188-byte MPEG packet transfer and then MUST de-assert it for exactly 32 clocks following the transfer of the last nibble of the MPEG packet.
+
+### H.5.2 Downstream data (ITU-T Rec. J.83 Annex B)
+
+Figure H.3 shows the protocol used to transfer data across this interface for ITU-T Rec. J.83 Annex B operation.
+
+![Timing diagram for Downstream data signal protocol for J.83 Annex B operation. It shows five signal lines: DS_CLK (a constant frequency square wave), DS_MSYNC_N (a signal that goes low during data transfer), DS_VALID_N (a signal that goes low during data transfer), DS_DATA (a stream of data packets with fields: SYNCH, SYNCL, IH, IL, 2H, 2L, followed by a break, then 187H, 187L, then SYNCH, SYNCL), and DS_DATAP (a stream of data packets with fields: SYNCH, followed by a break, then data, then SYNCH). The diagram includes break symbols (double slashes) to indicate gaps in the timing sequence. The label J.122_FH-3 is in the bottom right corner.](c8a6d227d5677de3c6aeb11eade9ea84_img.jpg)
+
+Timing diagram for Downstream data signal protocol for J.83 Annex B operation. It shows five signal lines: DS\_CLK (a constant frequency square wave), DS\_MSYNC\_N (a signal that goes low during data transfer), DS\_VALID\_N (a signal that goes low during data transfer), DS\_DATA (a stream of data packets with fields: SYNCH, SYNCL, IH, IL, 2H, 2L, followed by a break, then 187H, 187L, then SYNCH, SYNCL), and DS\_DATAP (a stream of data packets with fields: SYNCH, followed by a break, then data, then SYNCH). The diagram includes break symbols (double slashes) to indicate gaps in the timing sequence. The label J.122\_FH-3 is in the bottom right corner.
+
+**Figure H.3 – Downstream data signal protocol for J.83 Annex B operation**
+
+The following behaviour of DS\_CLK and DS\_VALID\_N is required:
+
+- DS\_CLK MUST NOT be gapped (it must have a constant frequency).
+- DS\_CLK frequency MUST be 1/4 of the downstream payload rate. The downstream payload rate is the data rate excluding the ITU-T Rec. J.83 Annex B framing overhead.
+- The MAC MUST keep DS\_VALID\_N always asserted.
+
+### H.5.3 Upstream data
+
+Figure H.4 shows the signalling protocol for this interface.
+
+![Timing diagram for the Upstream data protocol showing five signal lines over time. US_CLK is a periodic square wave. UD_SOB_N is a signal that goes low to indicate the start of a data block. UD_DV_N is a signal that goes low to indicate valid data. UD_DATA shows a sequence of nibbles: four 'X's, B0H, B0L, four 'X's, B1H, four 'X's, B1L, followed by a break, then BNH, BNL, B0H, B0L, and four 'X's. UD_DATAP shows a similar sequence but with empty boxes instead of nibbles. The diagram is labeled J.122_FH-4 in the bottom right corner.](b57a7a090805d3dfef36a0130a473432_img.jpg)
+
+Timing diagram for the Upstream data protocol showing five signal lines over time. US\_CLK is a periodic square wave. UD\_SOB\_N is a signal that goes low to indicate the start of a data block. UD\_DV\_N is a signal that goes low to indicate valid data. UD\_DATA shows a sequence of nibbles: four 'X's, B0H, B0L, four 'X's, B1H, four 'X's, B1L, followed by a break, then BNH, BNL, B0H, B0L, and four 'X's. UD\_DATAP shows a similar sequence but with empty boxes instead of nibbles. The diagram is labeled J.122\_FH-4 in the bottom right corner.
+
+**Figure H.4 – Upstream data protocol**
+
+It is a very simple protocol in which the upstream PHY indicates the presence of valid data on UD\_DATA by asserting UD\_DV\_N. The MAC has no ability to control the flow of data and is required to sample UD\_DATA on every rising clock edge on which UD\_DV\_N is asserted. The start of a data block is indicated by the PHY's assertion of UD\_SOB\_N. This signal MUST be asserted when the first nibble of the first byte of the data block is driven onto UD\_DATA.
+
+The MAC MUST keep track of length of each data block as it relates to the assertion of UD\_SOB\_N. If UD\_SOB\_N is asserted before the entire previous data block has been transferred, the MAC MUST drop the associated burst and generate an interrupt.
+
+If the FIRST\_STATUS byte indicates the absence of a PHY\_STATUS data block but the PHY transfers one, the PHY\_STATUS data block MUST be discarded by the MAC and an error MUST be signalled to the system.
+
+## H.5.4 Upstream control
+
+### H.5.4.1 Counter synchronization
+
+The master timestamp counter MUST reside in the MAC. The master mini-slot counter and master frame counter MUST reside in the PHY. The PHY MUST capture a timestamp snapshot on every frame boundary. When the system needs a timestamp snapshot for a UCD, it MUST read this snapshot using a single SPI bus transaction. The PHY MUST ensure that the timestamp snapshot does not change during the SPI bus read transaction.
+
+A common timestamp clock, TS\_CLK, MUST be externally provided to the upstream PHYs and the MACs. The frequency of this timestamp clock MUST be 10.24 MHz  $\pm 5$  ppm. The MAC MUST synchronize all PHYs to the timestamp value of the MAC. To accomplish this, the MAC MUST provide a frame sync pulse, TS\_FS\_N, to the PHYs that is synchronous to the positive edge of TS\_CLK and has a pulse width equal to one period of TS\_CLK.
+
+The 32-bit timestamp counter consists of a group of upper bits and a group of lower bits. The MAC and PHY MUST provide at least the following choices of upper and lower bit boundaries shown in Table H.6.
+
+**Table H.6 – Timestamp counter initialization options**
+
+| Upper bits | Lower bits | Frame sync interval |
+|------------|------------|---------------------|
+| 8          | 24         | 1638.4 ms           |
+| 9          | 23         | 819.2 ms            |
+| 10         | 22         | 409.6 ms            |
+| 11         | 21         | 204.8 ms            |
+| 12         | 20         | 102.4 ms            |
+
+Figure H.5 shows an example of the proper assertion of the TS\_FS\_N signal. Note that the TIMESTAMP is shown for reference and is not part of the upstream control interface. In this example, upper bits = 8.
+
+![Timing diagram showing TS_CLK, TS_FS_N, and TIMESTAMP signals. TS_CLK is a periodic square wave. TS_FS_N is a signal that goes low for two clock cycles. TIMESTAMP shows a sequence of values: XXFFF8, XXFFF9, XXFFFA, XXFFFB, XXFFFC, XXFFFD, XXFFFE, XXFFFF, XX0000, XX0001. The transition of TS_FS_N occurs between the XXFFFE and XXFFFF timestamp values.](65dfb5b0cce768997b08d0030d483f76_img.jpg)
+
+J.122\_FH-5
+
+Timing diagram showing TS\_CLK, TS\_FS\_N, and TIMESTAMP signals. TS\_CLK is a periodic square wave. TS\_FS\_N is a signal that goes low for two clock cycles. TIMESTAMP shows a sequence of values: XXFFF8, XXFFF9, XXFFFA, XXFFFB, XXFFFC, XXFFFD, XXFFFE, XXFFFF, XX0000, XX0001. The transition of TS\_FS\_N occurs between the XXFFFE and XXFFFF timestamp values.
+
+**Figure H.5 – Counter synchronization**
+
+The MAC MUST assert TS\_FS\_N two 10.24-MHz clock periods prior to the lower bits of the MAC timestamp counter equalling all zeros. The MAC SHOULD provide some sort of maskable indication to the system when TS\_FS\_N occurs so that the system will have time to programme the registers of the PHYs prior to the next assertion of TS\_FS\_N. The period of TS\_FS\_N is a function of the timestamp bit time and the number of lower bits from Table H.6. The variation of the TS\_FS\_N period is to allow the system designer to trade off system response time versus the time available to initialize a PHY chip.
+
+The PHY MUST provide all combinations of the following three initialization options when TS\_FS\_N is asserted:
+
+- The upper bits of the timestamp counter are specified and the lower bits are set to zero.
+- The full 8 bits of the frame counter are specified.
+- The full 32 bits of the mini-slot counter are specified.
+
+The specification of these counters is supplied across the SPI bus prior to the next frame sync pulse. Two TS\_CLK clock cycles after TS\_FS\_N occurs, the PHY chip MUST initialize the specified counters. These counters are loaded at configuration time, and not on every assertion of TS\_FS\_N. A single PHY may be re-initialized without the need to re-initialize or otherwise interrupt the operation of other PHYs or the MAC.
+
+During normal operation, the PHY MUST check that the lower bits of the PHY timestamp counter are exactly all zeros two 10.24-MHz clock cycles following every assertion of TS\_FS\_N. If the check is negative, the PHY MUST generate an interrupt and MUST provide status accessible over the SPI bus.
+
+#### H.5.4.2 Upstream control messages
+
+Figure H.6 shows a sample transaction.
+
+![Timing diagram for upstream control message transfer. It shows four signals: US_CLK (a periodic clock), UC_DV_N (asserted low during the transfer), UC_DATA (a burst of data), and UC_RDY_N (de-asserted high during the transfer). The diagram includes break symbols (//) to indicate time gaps.](16ad86204c0dc2490315c856c101159e_img.jpg)
+
+J.122\_FH-6
+
+Timing diagram for upstream control message transfer. It shows four signals: US\_CLK (a periodic clock), UC\_DV\_N (asserted low during the transfer), UC\_DATA (a burst of data), and UC\_RDY\_N (de-asserted high during the transfer). The diagram includes break symbols (//) to indicate time gaps.
+
+**Figure H.6 – Upstream control message transfer**
+
+The upstream control interface is used to transfer time-critical configuration information (messages) to the PHY. The most common type of message is an interval description message. This message informs the PHY of the arrival time and characteristics of an upcoming burst. The protocol of this interface is very simple. Following is a description of how this interface works:
+
+A transaction transfers a single upstream control message.
+
+- UC\_DV\_N MUST remain asserted for the entire duration of the upstream control message transfer.
+- The length of each upstream control message is inferred by its type.
+- UC\_DV\_N MUST be de-asserted for a minimum of one US\_CLK clock period to indicate the end of a transaction.
+- UC\_RDY\_N MAY be used to stop and start the flow of interval description messages. UC\_RDY\_N does not affect the transfer of other message types. If the PHY is receiving an interval description and does not want to receive a subsequent interval description, the PHY MUST de-assert UC\_RDY\_N at least two clock cycles of US\_CLK prior to the end of the current interval description. This de-assertion behaviour is shown in Figure H.6. The MAC MUST transfer a new interval description message within 10 US\_CLK periods of the assertion of UC\_RDY\_N if a new interval description message is available.
+
+### H.5.5 SPI bus
+
+Figure H.7 shows a SPI bus transaction.
+
+![Timing diagram for a SPI bus transaction. It shows four signals: SPI_CLK (a periodic clock), SPI_SSx_N (asserted low to select a slave), SPI_MOSI (Master Out Slave In data), and SPI_MISO (Master In Slave Out data). The diagram includes break symbols (//) to indicate time gaps.](5a4e859b13c7bb1cdd27378d12027bcd_img.jpg)
+
+J.122\_FH-7
+
+Timing diagram for a SPI bus transaction. It shows four signals: SPI\_CLK (a periodic clock), SPI\_SSx\_N (asserted low to select a slave), SPI\_MOSI (Master Out Slave In data), and SPI\_MISO (Master In Slave Out data). The diagram includes break symbols (//) to indicate time gaps.
+
+**Figure H.7 – SPI bus transaction**
+
+A transaction proceeds as follows:
+
+- The master asserts the select (SPI\_SSx\_N) of the desired slave device.
+- The master drives SPI\_MOSI with the appropriate command and data as described in clause H.8.4.
+
+- For write commands, the first byte of data driven on SPI\_MOSI is written to the register specified by the address in the command. The second byte of data (if it exists), is written to the next higher numbered address. Writes continue in this way until the master terminates the transaction by de-asserting SPI\_SSx\_N.
+- For read commands, the slave drives the read data on SPI\_MISO which is indicated by the address in the command. The first bit of this read data is driven one clock after the last bit of the command has been sampled. Read data from consecutively numbered addresses is driven until the master terminates the transaction by de-asserting SPI\_SSx\_N.
+
+SPI\_CLK MUST be driven (oscillate) for at least one clock period prior to the assertion of SPI\_SSx\_N, during the entire SPI bus transaction, and for one clock after the de-assertion of SPI\_SSx\_N. SPI\_CLK MAY be driven high or low at all other times.
+
+## H.6 Electrical specifications
+
+### H.6.1 DC specifications
+
+Devices which connect to DMPI must meet the requirements listed in Table H.7. Note that output high voltage and output high current specifications do not apply to the INT\_N output as it is open drain.
+
+**Table H.7 – DC characteristics**
+
+| Parameter           | Symbol          | Min | Max | Units | Comments |
+|---------------------|-----------------|-----|-----|-------|----------|
+| Input capacitance   |                 |     | 10  | pF    |          |
+| Input low voltage   | V <sub>il</sub> |     | 0.8 | V     |          |
+| Input high voltage  | V <sub>ih</sub> | 2.0 |     | V     |          |
+| Output low voltage  | V <sub>ol</sub> |     | 0.4 | V     |          |
+| Output high voltage | V <sub>oh</sub> | 2.4 |     | V     |          |
+| Output low current  | I <sub>ol</sub> | 4   |     | mA    |          |
+| Output high current | I <sub>oh</sub> | -4  |     | mA    |          |
+
+## H.7 Timing specifications
+
+### H.7.1 Downstream data
+
+**Table H.8 – Downstream data interface timing**
+
+| Parameter                    | Symbol           | Min. | Max.  | Units |
+|------------------------------|------------------|------|-------|-------|
+| DS_CLK frequency             | f                |      | 25    | MHz   |
+| DS_CLK low pulse width       | t <sub>lpw</sub> | 10   |       | ns    |
+| DS_CLK high pulse width      | t <sub>hpw</sub> | 10   |       | ns    |
+| DS_CLK rise/fall time        | t <sub>rf</sub>  |      | 4     | ns    |
+| DS_CLK jitter                | t <sub>j</sub>   |      | 97.66 | ns    |
+| Input set-up time to DS_CLK  | t <sub>su</sub>  | 10   |       | ns    |
+| Input hold time from DS_CLK  | t <sub>h</sub>   | 0    |       | ns    |
+| DS_CLK to signal valid delay | t <sub>eq</sub>  | 1    | 15    | ns    |
+
+## H.7.2 Upstream data
+
+**Table H.9 – Upstream data interface timing**
+
+| Parameter                    | Symbol           | Min. | Max.  | Units |
+|------------------------------|------------------|------|-------|-------|
+| US_CLK frequency             | f                | 33   | 40.96 | MHz   |
+| US_CLK low pulse width       | t <sub>lpw</sub> | 6.5  |       | ns    |
+| US_CLK high pulse width      | t <sub>hpw</sub> | 6.5  |       | ns    |
+| US_CLK rise/fall time        | t <sub>rf</sub>  |      | 1.5   | ns    |
+| Input set-up time to US_CLK  | t <sub>su</sub>  | 6    |       | ns    |
+| Input hold time from US_CLK  | t <sub>h</sub>   | 0    |       | ns    |
+| US_CLK to signal valid delay | t <sub>cq</sub>  | 1    | 9     | ns    |
+
+## H.7.3 Upstream control
+
+**Table H.10 – Upstream control interface timing**
+
+| Parameter                    | Symbol          | Min. | Max. | Units |
+|------------------------------|-----------------|------|------|-------|
+| Input set-up time to US_CLK  | t <sub>su</sub> | 6    |      | ns    |
+| Input hold time from US_CLK  | t <sub>h</sub>  | 0    |      | ns    |
+| US_CLK to signal valid delay | t <sub>cq</sub> | 1    | 9    | ns    |
+| Input set-up time to TS_CLK  | t <sub>su</sub> | 10   |      | ns    |
+| Input hold time from TS_CLK  | t <sub>h</sub>  | 0    |      | ns    |
+| TS_CLK to signal valid delay | t <sub>cq</sub> | 1    | 15   | ns    |
+
+## H.7.4 SPI bus
+
+**Table H.11 – SPI bus timing**
+
+| Parameter                                   | Symbol           | Min. | Max.  | Units |
+|---------------------------------------------|------------------|------|-------|-------|
+| SPI_CLK frequency                           | f                |      | 10.24 | MHz   |
+| SPI_CLK low pulse width                     | t <sub>lpw</sub> | 43.9 |       | ns    |
+| SPI_CLK high pulse width                    | t <sub>hpw</sub> | 43.9 |       | ns    |
+| SPI_CLK rise/fall time                      | t <sub>rf</sub>  |      | 4     | ns    |
+| SPI_MOSI or SPI_MISO set-up time to SPI_CLK | t <sub>su</sub>  | 15   |       | ns    |
+| SPI_MOSI or SPI_MISO hold time from SPI_CLK | t <sub>h</sub>   | 0    |       | ns    |
+| SPI_SSx_N set-up time to SPI_CLK rising     | t <sub>su</sub>  | 50   |       | ns    |
+| SPI_SSx_N setup time to SPI_CLK falling     | t <sub>su</sub>  | 25   |       | ns    |
+| SPI_SSx_N hold time from SPI_CLK            | t <sub>h</sub>   | 0    |       | ns    |
+| SPI_CLK to signal valid delay               | t <sub>cq</sub>  | 1    | 12    | ns    |
+
+## H.8 Data format and usage
+
+### H.8.1 Downstream data
+
+The data that passes from the MAC to the PHY is a stream of MPEG packets. The start of the SYNC byte is indicated by the assertion of the DS\_MSYNC\_N signal. Including the SYNC byte, each MPEG packet is 188 bytes in length.
+
+The MAC MUST generate NULL MPEG packets when there are no DOCS frames to be transmitted.
+
+### H.8.2 Upstream data
+
+#### H.8.2.1 Block format
+
+Data is passed from the upstream PHY to the MAC using a combination of variable sized units called upstream data blocks. Each of these data blocks has the generic format described in Table H.12 (except for the CHANNEL data block type as indicated in clause H.8.2.8.5).
+
+**Table H.12 – Upstream data block format**
+
+| Size (bytes) | Name         | Description                                                                   |
+|--------------|--------------|-------------------------------------------------------------------------------|
+| 1            | Block type   | Identifies the type of block                                                  |
+| 2            | Block length | Length of block data field in bytes (N)<br>Not present for CHANNEL block type |
+| N            | Block data   | Block data                                                                    |
+
+As can be seen from this table, each data block starts with a data block type. This type is used by the MAC to determine which type of data block data is being transferred. The data block length field contains the length in bytes of the data block data and is used by the MAC to find the end of the data block data field. In most cases, the data block type determines the format of the data block data field. The exception to this is the PHY\_STATUS type where the format of the data block data field is PHY-specific.
+
+Table H.13 gives a complete list of all block types.
+
+**Table H.13 – Upstream data block types**
+
+| Type      | Name        | Description                                                                                |
+|-----------|-------------|--------------------------------------------------------------------------------------------|
+| 0x00      | Reserved    | Reserved                                                                                   |
+| 0x01      | FIRST_DATA  | First data of burst contains 7 bytes of fixed-format status data and first data of burst   |
+| 0x02      | MIDDLE_DATA | Middle data of burst                                                                       |
+| 0x03      | LAST_DATA   | Last data of burst contains 4 bytes of fixed format status data and last data of burst     |
+| 0x04      | PHY_STATUS  | Status that should be passed to software<br>The maximum length of this block is 128 bytes. |
+| 0x05      | NO_BURST    | Indicates that no burst was received during a transmit opportunity                         |
+| 0x06      | CHANNEL     | Used to indicate the channel to which the next data block belongs.                         |
+| 0x07-0xff | Reserved    | Reserved                                                                                   |
+
+### H.8.2.2 FIRST\_DATA block
+
+Table H.14 shows the format of the FIRST\_DATA block.
+
+The FIRST\_DATA block is used by the PHY to transfer the beginning of a received burst. This block MUST contain the seven bytes of status information defined in the table. It MAY contain burst data as well. The block length of the FIRST\_DATA block MUST NOT be less than seven. Note that N = 7 is allowed.
+
+**Table H.14 – FIRST\_DATA data format**
+
+| Size (bytes) | Name           | Description                                                                                                                                                                                                                                     |
+|--------------|----------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 1            | FIRST_STATUS   | Bit 7:6, reserved, MUST be zero<br>Bit 5, new UCD, 1 ≥ First burst received on new UCD<br>Bit 4, PHY_STATUS data block present, 1 ≥ PHY_STATUS data block present<br>Bit 3:0, IUC, taken from the upstream control interval description message |
+| 2            | SID            | Bit 15:14, reserved, MUST be zero<br>Bit 13:0, SID, taken from the upstream control interval description message                                                                                                                                |
+| 4            | START_MINISLOT | Derived from the upstream control interval description message parameters                                                                                                                                                                       |
+| N – 7        | BURST_DATA     | First data of burst                                                                                                                                                                                                                             |
+
+### H.8.2.3 MIDDLE\_DATA block
+
+Table H.15 shows the format of the MIDDLE\_DATA block. The MIDDLE\_DATA block is used to transfer burst data.
+
+**Table H.15 – MIDDLE\_DATA data format**
+
+| Size (bytes) | Name       | Description          |
+|--------------|------------|----------------------|
+| N            | BURST_DATA | Middle data of burst |
+
+### H.8.2.4 LAST\_DATA block
+
+Table H.16 shows the format of the LAST\_DATA block. The LAST\_DATA block is used to transfer burst data. This block MUST contain the four bytes of status information defined in the table. It MAY also contain burst data. The block length of the LAST\_DATA block MUST NOT be less than four. Note that N = 4 is allowed.
+
+**Table H.16 – LAST\_DATA data format**
+
+| Size (bytes) | Name            | Description                                                                                                                                                                                                                                                                                      |
+|--------------|-----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| N – 4        | BURST_DATA      | Last data of burst                                                                                                                                                                                                                                                                               |
+| 1            | LAST_STATUS     | Bit 7:3, reserved, must be zero<br>Bit 2, internal PHY error, 1 ≥ internal PHY error<br>Bit 1, low energy; indicates that the burst power was below the desired threshold, 1 ≥ low energy<br>Bit 0, high energy; indicates that the burst power was above the desired threshold, 1 ≥ high energy |
+| 1            | GOOD_FEC        | The number of good FEC blocks in the burst;<br>must stop incrementing when count reaches 255;<br>must be zero if FEC is disabled for associated interval                                                                                                                                         |
+| 1            | CORRECTED_FEC   | The number of corrected FEC blocks in the burst;<br>must stop incrementing when count reaches 255;<br>must be zero if FEC is disabled for associated interval                                                                                                                                    |
+| 1            | UNCORRECTED_FEC | The number of uncorrected FEC blocks in the burst;<br>must stop incrementing when count reaches 255;<br>must be zero if FEC is disabled for associated interval                                                                                                                                  |
+
+#### H.8.2.5 PHY\_STATUS block
+
+Table H.17 shows the format of the PHY\_STATUS block. The PHY\_STATUS block is used to transfer PHY unique status to the MAC. The contents of this block are vendor-unique and are unrestricted.
+
+**Table H.17 – PHY\_STATUS data format**
+
+| Size (bytes) | Name       | Description                                                                                                                         |
+|--------------|------------|-------------------------------------------------------------------------------------------------------------------------------------|
+| N            | PHY_STATUS | PHY-specific status information such as channel characteristics (e.g., timing error, power error, frequency error, EQ coefficients) |
+
+#### H.8.2.6 NO\_BURST block
+
+Table H.18 shows the format of the NO\_BURST block. This block is used by the PHY to indicate that a valid burst was not received when one was expected. Absence of a valid burst may be caused by either no transmitter, multiple transmitters or a noise-corrupted transmission. DMPI does not specify the criteria by which the PHY distinguishes between these cases.
+
+**Table H.18 – NO\_BURST data format**
+
+| Size (bytes) | Name           | Description                                                                                                                                                   |
+|--------------|----------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 2            | SID_STATUS     | Bit 15, collision, collision occurred<br>Bit 14, no energy, no energy detected<br>Bit 13:0, SID, taken from the upstream control interval description message |
+| 4            | START_MINISLOT | Derived from the upstream control interval description message parameters                                                                                     |
+
+**Table H.18 – NO\_BURST data format**
+
+| Size (bytes) | Name   | Description                                                                                                                                                                                                       |
+|--------------|--------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 1            | IUC    | Bit 7:5, reserved, must be zero<br>Bit 4, new UCD, 1=> first NO_BURST block received on new UCD<br>Bit 3:0, IUC, taken from the upstream control interval description message                                     |
+| 2            | LENGTH | Taken from the upstream control interval description message<br>Note that for contention intervals, this is the length of the interval and not the length of each individual transmit opportunity in the interval |
+
+**H.8.2.7 CHANNEL block**
+
+Table H.19 shows the format of the CHANNEL block. The CHANNEL block is used by the PHY to indicate to which logical channel subsequent blocks belong.
+
+**Table H.19 – CHANNEL data format**
+
+| Size (bytes) | Name    | Description                                                |
+|--------------|---------|------------------------------------------------------------|
+| 1            | CHANNEL | Bit 7:3, reserved, must be zero<br>Bit 2:0, channel number |
+
+**H.8.2.8 Block usage****H.8.2.8.1 Overview**
+
+At least one data block MUST be transferred for every transmit opportunity. If a burst is received during a transmit opportunity, the appropriate series of data blocks MUST be transferred to the MAC (FIRST\_DATA, MIDDLE\_DATA, LAST\_DATA, PHY\_STATUS). If no burst is received, a NO\_BURST data block MUST be transferred unless the region was allocated to a SID that the system has reserved for no CM (e.g., the null SID as defined in clause A.2.1). Note that since contention regions have multiple transmit opportunities, more than one set of data blocks will likely be transferred to over the interface for each region (interval).
+
+The minimum amount of payload in a data block (the length of the block data field) MUST be 16 bytes with the following exceptions:
+
+- data blocks for bursts that are less than 16 bytes in length;
+- any LAST\_DATA data block.
+
+The upstream PHY SHOULD minimize the number of data blocks required to transfer a burst so as to minimize the amount of overhead on DMPI. However, nothing specific other than what is mentioned above is required.
+
+For non-contention intervals, the START\_MINISLOT MUST be equal to the START\_MINISLOT that was passed to the PHY in the corresponding interval description message (described in clause H.8.3). For contention intervals (IE types REQ and REQ/data), the PHY MUST calculate an accurate START\_MINISLOT value and return it in the appropriate data block (FIRST\_DATA or NO\_BURST). In general terms, this means that PHY MUST calculate the START\_MINISLOT for each data block by taking into account the number of mini-slots that have passed since the start of the interval. Specifically, the upstream PHY SHOULD use the IUC and SID in the upstream control interval description message to calculate a burst start offset from the original START\_MINISLOT
+
+value received in this message. The offset is then added to this START\_MINISLOT and returned to the MAC as the START\_MINISLOT in the appropriate upstream data block.
+
+#### **H.8.2.8.2 Burst data transfer**
+
+The transfer of a burst MUST be accomplished by transferring the following data blocks in the following order:
+
+- one FIRST\_DATA block;
+- zero to N MIDDLE\_DATA blocks;
+- one LAST\_DATA block;
+- zero or one PHY\_STATUS block.
+
+The only data block type that MAY be transferred after a FIRST\_DATA data block and before a LAST\_DATA data block is a MIDDLE\_DATA data block. Any other data block transferred between these two data blocks MUST be discarded by the MAC.
+
+In general, each data block will contain one FEC block of data. However, there is no specific requirement as to which data block types contain which parts of the burst data. The data MAY be distributed between the various data block types at the discretion of the PHY as long as the data block ordering shown above is maintained and the minimum block length requirements are respected. A data block type with a length of zero is also allowed. Every burst, regardless of size, MUST be transferred to the MAC using at least a FIRST\_DATA block and a LAST\_DATA data block. The PHY\_STATUS data block is optional with its presence indicated in the FIRST\_STATUS byte in the FIRST\_DATA data block. The MIDDLE\_DATA data block is optional.
+
+Typically, there will be some arbitrary delay between the transfer of one data block and the transfer of the next. It is the PHY's responsibility to assure that these delays do not interfere with the PHY's ability to keep up with the incoming data rate.
+
+Note that this series of data blocks is passed to the MAC any time a burst is received, regardless of the type of interval in which the burst was received (contention or non-contention).
+
+#### **H.8.2.8.3 No burst status transfer**
+
+It is sometimes useful for the system to know when no usable burst was received during a transmit opportunity. This can happen when there is no transmitter (no energy) in the opportunity, there is more than one transmitter (a collision), or noise corrupted a transmission. For a contention region, knowledge of unused opportunities or those with collisions helps software optimize its scheduling of contention regions (their duration and frequency). For non-contention regions, these same events could be an indication of a problem with a CM, or they could be a result of illegal or malicious use of the US bandwidth.
+
+The NO\_BURST data block contains two status bits. The one called "collision" indicates that a collision occurred during the transmit opportunity. The other, called "no energy", indicates that there was no energy detected during the transmit opportunity. If neither is set, it means that there was energy but that no preamble was found. Both of these bits must not be set at the same time.
+
+#### **H.8.2.8.4 UCD change indication**
+
+In order to allow the system to properly size grants for bandwidth requests that were received prior to a UCD change but are granted after such a UCD change, the MAC needs to be notified that a new UCD is in effect. This notification is achieved via "new UCD" status bits in the NO\_BURST and FIRST\_DATA data blocks. The PHY MUST set the new UCD bit of the first data block sent to the MAC after a UCD change (FIRST\_DATA or NO\_BURST, whichever is sent first). The new UCD bit of these data blocks MUST be zero at all other times.
+
+#### H.8.2.8.5 Logical channel support
+
+For upstream PHYs that support multiple logical channels, a data block type called CHANNEL is used to specify to that logical channel each data block belongs. This data block contains a single byte of payload that is the channel number (zero to seven inclusive). Since the data block is a fixed length and is potentially required for every other data block transferred, the length bytes are omitted from the normal data block format and only the data block type and block data are transferred. So, a CHANNEL block is always two bytes long (including the type byte).
+
+It is important to note that the channel data block is only used to distinguish between data received on logical channels within the same RF channel. Since each PHY has its own DMPI interface, the RF channel to which data belongs is inferred by the PHY's connection to the MAC.
+
+The CHANNEL data block is used as follows:
+
+- The CHANNEL data block sets the "current" channel for transmitted data blocks. After reset, the MAC must set the current channel to zero.
+- The current channel is always the channel number contained in the most recently transmitted CHANNEL data block. For this reason, transmission of a CHANNEL data blocks is only required when a change in the current channel is desired.
+
+Since the MAC sets the current channel to zero prior to receipt of any CHANNEL data blocks, PHYs that support a single channel are not required to support this data block type. In cases where multiple CHANNEL data blocks are transferred in succession, the last one received prior to the transfer of one of the other data blocks will be considered valid and the others that preceded it will be ignored. NO\_BURST data blocks may be preceded by a CHANNEL data block. If a series of NO\_BURST data blocks for the same channel are transmitted to the MAC, only one CHANNEL data block is required (transferred prior to the first NO\_BURST data block).
+
+All data blocks associated with a single burst MUST be transferred contiguously over the upstream data interface. Specifically, this would mean that FIRST\_DATA, MIDDLE\_DATA, LAST\_DATA, PHY\_STATUS would all be transferred for a given burst of a given channel before any other data blocks were transferred for another channel. A CHANNEL data block MUST precede the first data block (NO\_BURST or FIRST\_DATA) that belongs to a channel that is different than the one which preceded it. The PHY MAY transfer a CHANNEL data block prior to the FIRST\_DATA block of every burst. CHANNEL data blocks MUST NOT be transferred immediately before any of the other data block associated with a burst.
+
+#### H.8.3 Upstream control
+
+The upstream control interface carries two different messages. One of them is used to describe upcoming bursts. The other is used to indicate UCD changes.
+
+The format of an upstream control message is shown in Table H.20.
+
+**Table H.20 – Upstream control message format**
+
+| Size (bits) | Name    | Description                                                                                                            |
+|-------------|---------|------------------------------------------------------------------------------------------------------------------------|
+| 3           | TYPE    | Message type                                                                                                           |
+| 3           | CHANNEL | Logical channel number                                                                                                 |
+| N           | PAYLOAD | Payload of message                                                                                                     |
+| 1           | PARITY  | Even parity for all bits in the message (the number of 1s across all bits in {TYPE, CHANNEL, PAYLOAD, PARITY} is even) |
+
+Table H.21 shows the message type encoding.
+
+**Table H.21 – Upstream message types**
+
+| Type    | Name                 | Description                         |
+|---------|----------------------|-------------------------------------|
+| 0x0     | INTERVAL_DESCRIPTION | Describes an interval               |
+| 0x1     | UCD_CHANGE           | Indicates a UCD change has occurred |
+| 0x2-0x7 | Reserved             | Reserved                            |
+
+**H.8.3.1 Interval description message**
+
+Table H.22 describes the format of the interval description message PAYLOAD.
+
+**Table H.22 – Upstream control burst description PAYLOAD format**
+
+| Size (bits) | Name           | Description                                                      |
+|-------------|----------------|------------------------------------------------------------------|
+| 14          | SID            | Expected SID from MAP IE                                         |
+| 4           | IUC            | IUC from MAP IE                                                  |
+| 14          | LENGTH         | Length in mini-slots                                             |
+| 32          | START_MINISLOT | Starting mini-slot of interval (alloc start time + offset of IE) |
+| 3           | PSC            | PHY_STATUS control                                               |
+
+The MAC builds these interval description messages from the information present in the DOCS MAPs that have been generated for the logical channels that the PHY is servicing. The MAC MUST transfer only one interval description message to the PHY for an interval allocation that might describe an interval that has more than one transmit opportunity (e.g., a REQ, REQ/DATA). The MAC MAY generate interval description messages for interval allocations to the NULL SID, but MUST NOT generate interval description messages for interval allocations for the NULL SID if they overlap with interval allocations for non-NULL SIDs on other logical channels being serviced by the same PHY. Interval description messages for the NULL SID MAY be associated with any currently active logical channel. In contrast to MAP messages, the set of all interval description messages from the MAC taken together need not describe every mini-slot on the logical channels in question; the MAC MAY refrain from sending interval description messages to describe inactive time periods on any or all logical channels. So as to minimize the complexity and buffering requirements of the PHY, the MAC MUST sort the interval descriptions from all logical channels, put them into chronological order, and deliver them to the PHY in this order. Note that interval description messages MUST NOT be transferred for the NULL IE, data acknowledgement IEs, or data grants pending (since none of these is an interval allocation).
+
+The system is allowed to schedule the initial maintenance regions of all logical channels of a physical channel to occur simultaneously. This type of overlap MUST be handled as follows:
+
+- The MAC MUST transfer an interval description for only one of the logical channels.
+- The interval description that is transferred MUST be the one with the earliest start time. If more than one interval description has the earliest start time, the MAC MAY choose any of these overlapping interval descriptions to pass to the PHY.
+- The PHY MUST accept any of the logical channel numbers it supports for this interval description.
+
+The system software is responsible for knowing that bursts received during initial ranging could be from CMs on any of the logical channels.
+
+It is possible for there to be illegal overlap of intervals for the logical channels. An illegal overlap is defined to be an overlap of intervals other than initial maintenance. The PHY MAY detect these
+
+illegal overlaps. If the PHY performs this function, it MUST generate an interrupt to alert the system of such an event. It MUST capture the illegally overlapped interval description and hold it in SPI bus-accessible registers until software acknowledges its receipt.
+
+The PSC field of the interval description message is used to control the contents of the PHY\_STATUS block. The usage of this field is summarized below:
+
+- If PSC = 000, the contents of the PHY\_STATUS block is determined through PHY programmable registers.
+- If PSC is any other value, the contents of the PHY\_STATUS block are vendor-specific.
+
+The MAC and PHY MUST support PSC = 000.
+
+The MAC and PHY MAY support other values.
+
+### H.8.3.2 UCD change message
+
+Table H.23 describes the format of the UCD change message PAYLOAD.
+
+**Table H.23 – UCD change PAYLOAD format**
+
+| Size (bits) | Name | Description                             |
+|-------------|------|-----------------------------------------|
+| 8           | CCC  | Configuration change count from the MAP |
+
+The MAC MUST send this message before sending the first interval description message after a UCD change. This message MUST NOT be sent at any other time.
+
+### H.8.4 SPI bus
+
+In order to perform an SPI bus transaction, the master MUST drive SPI\_MOSI with a bitstream of the following format:
+
+**Table H.24 – SPI bus transaction format**
+
+| Size (bits) | Name         | Description                   |
+|-------------|--------------|-------------------------------|
+| 4           | DEVICE_ID    | Device ID                     |
+| 3           | RSVD         | Reserved                      |
+| 1           | WRITE        | 1 = write, 0 = read           |
+| 16          | REGISTER_ADD | Register address              |
+| N × 8       | WRITE_DATA   | Write data; ignored for reads |
+
+The DEVICE\_ID is used to address PHY devices that are integrated into the same physical package and share a single SPI select. DEVICE\_ID MUST be zero for accesses to single PHY devices.
+
+## **Annex I**
+
+### **(Set aside)**
+
+NOTE – This annex is left blank intentionally to avoid any possible confusion with Appendix I.
+
+## **Annex J**
+
+### **Japan specification additions**
+
+(This annex forms an integral part of this Recommendation)
+
+This annex applies to the third technology option referred to in clause 1.1, "scope".
+
+This annex describes the physical layer MAC layer specifications required for what are generally called Japan-DOCS cable-modems. This is an optional annex and in no way affects certification of North American and European DOCS 1.x and DOCS 2.0 modems.
+
+The numbering of the clauses has been made so that the suffix after the J refers to the part of the specification which has changed. As a consequence, some clauses are missing in this annex because no change is required.
+
+#### **J.1 Scope and purpose**
+
+See clause 1.
+
+#### **J.2 References**
+
+See clause 2.
+
+#### **J.3 Glossary**
+
+See clause 3.
+
+#### **J.4 Functional assumptions**
+
+See clause 4.
+
+##### **J.4.1 Broadband access network**
+
+A coaxial-based broadband access network is assumed. This may take the form of either an all-coax or hybrid-fibre/coax (HFC) network. The generic term "cable network" is used here to cover all cases.
+
+A cable network uses a shared-medium, tree-and-branch architecture with analogue transmission. The key functional characteristics assumed in this annex are the following:
+
+- two-way transmission;
+- a maximum optical/electrical spacing between the CMTS and the most distant CM of 160 km, although typical maximum separation may be 16 to 24 km;
+- a maximum differential optical/electrical spacing between the CMTS and the closest and most distant modems of 160 km, although this would typically be limited to 24 km.
+
+## **J.4.2 Equipment assumptions**
+
+### **J.4.2.1 Frequency plan**
+
+In the downstream direction, the cable system is assumed to have a passband with a lower edge 90 MHz and an upper edge that is implementation-dependent but is typically in the range of 350 MHz to 770 MHz. Within that passband, NTSC analogue television signals in 6-MHz channels are assumed to be present on the standard Japan frequency plans, as well as other narrow-band and wideband digital signals.
+
+In the upstream direction, the cable system MAY have a subsplit (10 MHz to 55 MHz) passband. NTSC analogue television signals in 6 MHz channels MAY be present, as well as other signals.
+
+### **J.4.2.2 Compatibility with other services**
+
+Refer to clause 4.2.2.
+
+### **J.4.2.3 Fault isolation impact on other users**
+
+Refer to clause 4.2.3.
+
+### **J.4.2.4 Cable system terminal devices**
+
+The CM MUST meet and SHOULD exceed all applicable regulations for cable system termination devices and cable ready consumer equipment as defined in voluntary control council for interference by information technology equipment (VCCI). None of these specific requirements may be used to relax any of the specifications contained elsewhere within VCCI. The CMTS SHOULD meet and exceed all applicable regulations for Class-B ITE as well.
+
+## **J.4.3 RF channel assumptions**
+
+Refer to clause 4.3.
+
+### **J.4.3.1 Transmission downstream**
+
+The RF channel transmission characteristics of the cable network in the downstream direction are described in Table J.4-1. These numbers assume total average power of a digital signal in a 6 MHz channel bandwidth for carrier levels unless indicated otherwise. For impairment levels, the numbers in Table J.4-1 assume average power in a bandwidth in which the impairment levels are measured in a standard manner for cable TV system. For analogue signal levels, the numbers in Table J.4-1 assume peak envelope power in a 6-MHz channel bandwidth. All conditions are present concurrently. No combination of the following parameters will exceed any stated interface limit defined elsewhere in this Recommendation.
+
+**Table J.4-1 – Assumed downstream RF channel transmission characteristics  
+(see Note 1)**
+
+| <b>Parameter</b>                                                                                                                                  | <b>Value</b>                                                                                                  |
+|---------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------|
+| Frequency range                                                                                                                                   | Cable system normal downstream operating range is from 90 MHz to as high as 770 MHz.                          |
+| RF channel spacing (design bandwidth)                                                                                                             | 6 MHz                                                                                                         |
+| Transit delay from headend to most distant customer                                                                                               | ≤0.800 ms (typically much less)                                                                               |
+| Carrier-to-noise ratio in a 6-MHz band                                                                                                            | Not less than 26 dBrms (@ 5.274 MHz) for 64QAM<br>Not less than 33 dBrms (@ 5.274 MHz) for 256QAM<br>(Note 2) |
+| Carrier-to-composite triple beat distortion ratio                                                                                                 | Not less than 40 dBrms for 64QAM<br>Not less than 51 dBrms for 256QAM<br>(Note 2)                             |
+| Carrier-to-any other discrete interference (ingress)                                                                                              | Not less than 26 dBrms for 64QAM<br>Not less than 33 dBrms for 256QAM<br>(Note 2)                             |
+| Amplitude ripple                                                                                                                                  | 3 dB within the design bandwidth                                                                              |
+| Micro reflections bound for dominant echo                                                                                                         | Figure J.4-1                                                                                                  |
+| Maximum analogue video carrier level at the CM input                                                                                              | 85 dB $\mu$ V peak                                                                                            |
+| Maximum number of carriers                                                                                                                        | 111 (770 MHz system)                                                                                          |
+| NOTE 1 – Transmission is from the headend combiner to the CM input at the customer location.                                                      |                                                                                                               |
+| NOTE 2 – Measured relative to a QAM signal level (rms) that is –10 dB for 64QAM, –4 dB for 256QAM to the nominal video level (peak) in the plant. |                                                                                                               |
+
+![Figure J.4-1: Micro reflections bound for dominant echo. A line graph showing Micro reflection level (dB) on the y-axis (from -35 to 0) versus Micro reflection time (μs) on the x-axis (logarithmic scale from 0.1 to 10). The graph shows a downward-sloping line starting at -15 dB at 0.1 μs, reaching -30 dB at 1.5 μs, and then leveling off. Two horizontal lines are shown at -30 dB and -32 dB, labeled '-30 for 64QAM' and '-32 for 256QAM' respectively. A vertical dashed line is at 0.25 μs and a solid vertical line is at 1.5 μs.](f17a2bc8b89089561fc93cee086daf84_img.jpg)
+
+Figure J.4-1: Micro reflections bound for dominant echo. A line graph showing Micro reflection level (dB) on the y-axis (from -35 to 0) versus Micro reflection time (μs) on the x-axis (logarithmic scale from 0.1 to 10). The graph shows a downward-sloping line starting at -15 dB at 0.1 μs, reaching -30 dB at 1.5 μs, and then leveling off. Two horizontal lines are shown at -30 dB and -32 dB, labeled '-30 for 64QAM' and '-32 for 256QAM' respectively. A vertical dashed line is at 0.25 μs and a solid vertical line is at 1.5 μs.
+
+J.122\_FJ-4-1
+
+**Figure J.4-1 – Micro reflections bound for dominant echo**
+
+### J.4.3.2 Transmission upstream
+
+The RF channel transmission characteristics of the cable network in the upstream direction assumed for the purposes of minimal operating capability are described in Table J.4-2. All conditions are present concurrently.
+
+**Table J.4-2 – Assumed upstream RF channel transmission characteristics (see Note 1)**
+
+| Parameter                                                                                                                                                                                             | Value                                                                        |
+|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------|
+| Frequency range                                                                                                                                                                                       | 10 MHz to 55 MHz edge to edge                                                |
+| Transit delay from the most distant CM to the nearest CM or CMTS                                                                                                                                      | ≤0.800 ms (typically much less)                                              |
+| Carrier-to-interference plus ingress (the sum of noise, distortion, common path distortion and cross modulation, and the sum of discrete and broadband ingress signals, impulse noise excluded) ratio | Not less than 25 dB (Note 2)                                                 |
+| Carrier hum modulation                                                                                                                                                                                | Not greater than -23 dBc (7.0 %)                                             |
+| Burst noise                                                                                                                                                                                           | Not longer than 10 μs at a 1-kHz average rate for most cases (Notes 3 and 4) |
+| Amplitude ripple 10 MHz to 55 MHz                                                                                                                                                                     | 0.5 dB/MHz                                                                   |
+| Group delay ripple 10 MHz to 55 MHz                                                                                                                                                                   | 200 ns/MHz                                                                   |
+
+**Table J.4-2 – Assumed upstream RF channel transmission characteristics  
+(see Note 1)**
+
+| Parameter                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Value                                                                                              |
+|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------|
+| Micro reflections – single echo                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | –10 dB @ $\leq 0.5 \mu\text{s}$<br>–20 dB @ $\leq 1.0 \mu\text{s}$<br>–30 dB @ $> 1.0 \mu\text{s}$ |
+| Seasonal and diurnal reverse gain (loss) variation                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         | Not greater than 14 dB min. to max.                                                                |
+| NOTE 1 – Transmission is from the CM output at the customer location to the headend.<br>NOTE 2 – Ingress avoidance or tolerance techniques may be used to ensure operation in the presence of time-varying discrete ingress signals that could be as high as 10 dBc. The ratios are guaranteed only within the digital carrier channels.<br>NOTE 3 – Amplitude and frequency characteristics sufficiently strong to partially or wholly mask the data carrier.<br>NOTE 4 – Impulse noise levels more prevalent at lower frequencies ( $<15 \text{ MHz}$ ). |                                                                                                    |
+
+#### J.4.3.2.1 Availability
+
+Refer to clause 4.3.2.1.
+
+#### J.4.4 Transmission levels
+
+The nominal power level of the downstream CMTS signal(s) within a 6 MHz channel is targeted to be in the range –10 dBc to –6 dBc relative to the analogue video carrier level and will normally not exceed the analogue video carrier level. The 256QAM downstream carrier level SHOULD be carefully chosen for two reasons. One is to avoid any interference to the adjacent analogue video carrier, the other is to maintain required carrier-to-noise ratio. Normally the 256QAM downstream signal MAY NOT be allocated to any channels that are adjacent to the analogue video carrier.
+
+The nominal power level of the upstream CM signal(s) will be as low as possible to achieve the required margin above noise and interference. Uniform power loading per unit bandwidth is commonly followed in setting upstream signal levels, with specific levels established by the cable network operator to achieve the required carrier-to-noise and carrier-to-interference ratios.
+
+#### J.4.5 Frequency inversion
+
+Refer to clause 4.5.
+
+### J.5 Communication protocols
+
+Refer to clause 5.
+
+### J.6 Physical media dependent sublayer specification
+
+#### J.6.1 Scope
+
+This clause applies to the third technology option referred to in clause 1.1, "scope". In those cases where the requirements for three technology options are identical, a reference is provided to the main text.
+
+Whenever any reference in this clause to spurious emissions conflicts with any legal requirement for the area of operation, the latter shall take precedence.
+
+## J.6.2 Upstream
+
+### J.6.2.1 Overview
+
+The upstream physical media dependent (PMD) sublayer uses an FDMA/TDMA (herein called TDMA mode) or FDMA/TDMA/S-CDMA (herein called S-CDMA mode) burst type format, which provides six modulation rates and multiple modulation formats. The use of TDMA or S-CDMA mode is configured by the CMTS via MAC messaging.
+
+FDMA (frequency division multiple access) indicates that multiple RF channels are assigned in the upstream band. A CM transmits on a single RF channel unless reconfigured to change channels. TDMA (time division multiple access) indicates that upstream transmissions have a burst nature. A given RF channel is shared by multiple CMs via the dynamic assignment of time slots. S-CDMA (synchronous code division multiple access) indicates that multiple CMs can transmit simultaneously on the same RF channel and during the same TDMA time slot, while being separated by different orthogonal codes.
+
+In this Recommendation, the following naming conventions are used. For TDMA, the term "modulation rate" refers to the RF channel symbol rate (144 to 4608 ksymb/s). For S-CDMA, the term "chip rate", which is the modulation rate (1152 to 4608 kHz) of a single bit of the S-CDMA spreading code, may be used interchangeably with "modulation rate". The "modulation interval" is the symbol period (TDMA mode) or chip period (S-CDMA mode) and is the reciprocal of the modulation rate. At the output of the spreader, a group of 128 chips, which comprise a single S-CDMA spreading code and are the result of spreading a single information (QAM constellation) symbol, is referred to as a "spread symbol". The period of a spread symbol (128 chips) is called a "spreading interval". A "burst" is a physical RF entity that contains a single preamble plus data, and (in the absence of preceding and following bursts) exhibits RF energy ramp-up and ramp-down.
+
+In some cases, logical zeros are used to pad data blocks; this indicates data with zero-valued binary bits, which result in non-zero transmitted RF energy. In other cases, a numerical zero is used; this denotes, for example, symbols that result in zero transmitted RF energy (after ramp-up and ramp-down are taken into account).
+
+The modulation format includes pulse shaping for spectral efficiency, is carrier-frequency agile, and has selectable output power levels.
+
+Each burst supports a flexible modulation order, modulation rate, preamble, randomization of the payload, and programmable FEC encoding.
+
+All of the upstream transmission parameters associated with burst transmission outputs from the CM are configurable by the CMTS via MAC messaging. Many of the parameters are programmable on a burst-by-burst basis.
+
+The PMD sublayer can support a near-continuous mode of transmission, wherein ramp-down of one burst MAY overlap the ramp-up of the following burst, so that the transmitted envelope is never zero. In TDMA mode, the system timing of the TDMA transmissions from the various CMs MUST provide that the centre of the last symbol of one burst and the centre of the first symbol of the preamble of an immediately following burst are separated by at least the duration of five symbols. The guard time MUST be greater than or equal to the duration of five symbols plus the maximum timing error. Timing error is contributed by both the CM and CMTS. CM timing performance is specified in clause 6.2.19. Maximum timing error and guard time may vary with CMTSs from different vendors.
+
+The PMD sublayer also supports a synchronous mode of transmission when using S-CDMA, wherein ramp-down of one burst MAY completely overlap the ramp-up of the following burst, so that the transmitted envelope is never zero. The system timing of the S-CDMA transmissions from the various CMs MUST provide adequate timing accuracy so that different CMs do not appreciably
+
+interfere with each other. S-CDMA utilizes precise synchronization so that multiple CMs can transmit simultaneously.
+
+The upstream modulator is part of the cable modem that interfaces with the cable network. The modulator contains the electrical-level modulation function and the digital signal-processing function; the latter provides the FEC, preamble prepend, symbol mapping and other processing steps.
+
+At the demodulator, similar to the modulator, there are two basic functional components: the demodulation function and the signal processing function. The demodulator resides in the CMTS and there is one demodulation function (not necessarily an actual physical demodulator) for each carrier frequency in use. The demodulation function receives all bursts on a given frequency.
+
+The demodulation function of the demodulator accepts a varying-level signal centred around a commanded power level and performs symbol timing and carrier recovery and tracking, burst acquisition and demodulation. Additionally, the demodulation function provides an estimate of burst timing relative to a reference edge, an estimate of received signal power, may provide an estimate of signal-to-noise ratio, and may engage adaptive equalization to mitigate the effects of:
+
+- a) echoes in the cable plant;
+- b) narrow-band ingress; and
+- c) group delay.
+
+The signal-processing function of the demodulator performs the inverse processing of the signal-processing function of the modulator. This includes accepting the demodulated burst data stream and decoding, etc. The signal-processing function also provides the edge-timing reference and gating-enable signal to the demodulators to activate the burst acquisition for each assigned burst slot. The signal-processing function may also provide an indication of successful decoding, decoding error, or fail-to-decode for each codeword and the number of corrected Reed-Solomon symbols in each codeword. For every upstream burst, the CMTS has a prior knowledge of the exact burst length in modulation intervals (see clauses 6.2.19, 6.2.5.1, and A.2).
+
+#### **J.6.2.2 Signal processing requirements**
+
+Refer to clause 6.2.2.
+
+#### **J.6.2.3 Modulation formats**
+
+The modulation formats listed here specify requirements for J.122-compliant equipment. Cable operators are free to configure the modulation format to best address their system characteristics and application requirements.
+
+The upstream modulator MUST provide QPSK and 16QAM differential encoded modulations for TDMA.
+
+The upstream modulator MUST provide QPSK, 8QAM, 16QAM, 32QAM and 64QAM modulations for TDMA and S-CDMA channels.
+
+The upstream modulator MUST provide QPSK, 8QAM, 16QAM, 32QAM, 64QAM and 128QAM TCM encoded modulations for S-CDMA channels.
+
+The upstream demodulator MAY support QPSK and 16QAM differential modulation for TDMA.
+
+The upstream demodulator MUST support QPSK, 16QAM and 64QAM modulations for TDMA and S-CDMA channels.
+
+The upstream demodulator MAY support 8QAM and 32QAM modulation for TDMA and S-CDMA channels.
+
+The upstream demodulator MAY support QPSK, 8QAM, 16QAM, 32QAM, 64QAM and 128QAM TCM encoded modulations for S-CDMA channels.
+
+#### **J.6.2.4 R-S encode**
+
+Refer to clause 6.2.4.
+
+#### **J.6.2.5 R-S frame structure**
+
+Refer to clause 6.2.5.
+
+#### **J.6.2.6 TDMA byte interleaver**
+
+Refer to clause 6.2.6.
+
+#### **J.6.2.7 Scrambler (randomizer)**
+
+Refer to clause 6.2.7.
+
+#### **J.6.2.8 TCM encoder**
+
+Refer to clause 6.2.8.
+
+#### **J.6.2.9 Preamble prepend**
+
+Refer to clause 6.2.9.
+
+#### **J.6.2.10 Modulation rates**
+
+In TDMA mode, the CM upstream modulator MUST provide all modulations at 144, 288, 576, 1152, 2304 and 4608 ksymb/s. In S-CDMA mode, the CM upstream modulator MUST provide all modulations at 1152, 2304 and 4608 ksymb/s.
+
+In TDMA mode, the CMTS upstream demodulator MUST be able to support demodulation at 144, 288, 576, 1152, 2304 and 4608 ksymb/s. In S-CDMA mode, the CMTS upstream demodulator MUST be able to support demodulation at 1152, 2304 and 4608 ksymb/s.
+
+This variety of modulation rates, and flexibility in setting upstream carrier frequencies, permits operators to position carriers in gaps in the pattern of narrow-band ingress, as discussed in Annex G.
+
+The modulation rate for each upstream channel is defined in an upstream channel descriptor (UCD) MAC message. All CMs using that upstream channel MUST use the defined modulation rate for upstream transmissions.
+
+#### **J.6.2.11 S-CDMA framer and interleaver**
+
+##### **J.6.2.11.1 S-CDMA framing considerations**
+
+Refer to clause 6.2.11.1.
+
+##### **J.6.2.11.2 Mini-slot numbering**
+
+In normal operation, the MAC will request the PHY to transmit a burst of length  $n$  mini-slots, starting at mini-slot  $m$ , as defined by the MAP. All CMs and the CMTS MUST have a common protocol of how mini-slots are numbered, and how they are mapped onto the physical layer framing structure. This common protocol is obtained from information in the SYNC and upstream channel descriptor (UCD) messages (these messages are described in clause 8.3.2, "time synchronization (SYNC)", and clause 8.3.3, "upstream channel descriptor (UCD)").
+
+Mini-slots are mapped onto frames starting at the first active code (usually code number 0), are numbered sequentially through the remainder of the frame (code number 127), and then wrap to the next sequential frame. Mini-slots are mapped onto a group of consecutive codes.
+
+The CMTS and the CMs require a common protocol for mini-slot numbering. For operation on a TDMA channel, this is achieved solely through recovery of the timestamp. Since the time duration of an S-CDMA frame is not necessarily a power-of-2 multiple of the 9.216-MHz reference, the
+
+timestamp rollover (at  $2^{32}$  counts) is not necessarily at an S-CDMA frame boundary. Therefore, an additional synchronization step is required.
+
+The CMTS MUST identify frame boundaries relative to the timestamp counter on a periodic basis. This is called the timestamp snapshot and must be sent in the UCD for each upstream S-CDMA channel.
+
+The CMTS MUST maintain a frame counter and a mini-slot counter, and MUST sample these values along with the timestamp, on a frame boundary, as shown in Figure J.6-5. The CMTS MUST obtain a new sample prior to sending each UCD message.
+
+![Figure J.6-5 – Timestamp snapshot. The diagram illustrates the timing and data structure for a timestamp snapshot in an S-CDMA system. It shows a grid of mini-slots across multiple codes (0-127) over three frames (f, f+1, f+2). Codes 127 and 126 have mini-slots at m+62, m+125, and m+188. Codes 3, 2, and 1 have mini-slots at m, m+63, and m+126. Code 0 is shaded. A timeline at the bottom shows timestamp counts t1, t2, t3, t4. Arrows point from the mini-slot at m+63 in Code 2 to a 'Timestamp snapshot' box containing 'Timestamp count' (32 bits), 'Mini-slot number' (32 bits), and 'Frame number' (8 bits). This box is labeled 'Included in UCD'. The entire snapshot is labeled 'Timestamp snapshot'.](fdc14f5fb012540451a6e7d2f890062f_img.jpg)
+
+The diagram shows a grid of mini-slots across multiple codes (0-127) over three frames (f, f+1, f+2). The top part of the diagram shows the mini-slot structure for several codes: Code 127 and Code 126 have mini-slots at  $m+62$ ,  $m+125$ , and  $m+188$ . Code 3, Code 2, and Code 1 have mini-slots at  $m$ ,  $m+63$ , and  $m+126$ . Code 0 is shaded. The mini-slots are grouped into  $K$  spreading intervals. Below the grid, a timeline shows timestamp counts  $t_1$ ,  $t_2$ ,  $t_3$ ,  $t_4$ . Arrows point from the mini-slot at  $m+63$  in Code 2 to a 'Timestamp snapshot' box. This box contains three fields: 'Timestamp count' (32 bits), 'Mini-slot number' (32 bits), and 'Frame number' (8 bits). An arrow points from this box to the text 'Included in UCD'. The entire snapshot is labeled 'Timestamp snapshot'.
+
+Figure J.6-5 – Timestamp snapshot. The diagram illustrates the timing and data structure for a timestamp snapshot in an S-CDMA system. It shows a grid of mini-slots across multiple codes (0-127) over three frames (f, f+1, f+2). Codes 127 and 126 have mini-slots at m+62, m+125, and m+188. Codes 3, 2, and 1 have mini-slots at m, m+63, and m+126. Code 0 is shaded. A timeline at the bottom shows timestamp counts t1, t2, t3, t4. Arrows point from the mini-slot at m+63 in Code 2 to a 'Timestamp snapshot' box containing 'Timestamp count' (32 bits), 'Mini-slot number' (32 bits), and 'Frame number' (8 bits). This box is labeled 'Included in UCD'. The entire snapshot is labeled 'Timestamp snapshot'.
+
+J.122\_FJ-6-5
+
+**Figure J.6-5 – Timestamp snapshot**
+
+Each CM MUST maintain a timestamp counter, mini-slot counter and frame counter functionally identical to the CMTS.
+
+From the UCD message, the CM receives the CMTS timestamp snapshot and parameters from which it can calculate the number of time counts per S-CDMA frame. Using modulo arithmetic, the CM can then calculate accurate values for timestamp, mini-slot and frame counters at any point into the future.
+
+The CM can then update its local mini-slot and frame counters at an appropriate timestamp counter value. At this point, the CM representation of mini-slots and frames are aligned with those in the CMTS.
+
+The CMTS and CM MUST implement a 32-bit timestamp counter, a 32-bit mini-slot counter, and an 8-bit frame counter, as follows:
+
+- The mini-slot counter MUST contain the value of the first mini-slot of the frame when it is sampled. It MAY be incremented by the number of mini-slots per frame, once per frame interval. The mini-slot counter will use all 32 bits and mini-slot numbers will therefore range from 0 to  $2^{32} - 1$ .
+- The only specified function for the frame counter is to reset the code-hopping sequence at the frame 0 (modulo 256) boundary, as defined in clause 6.2.14.1, "code hopping".
+
+The frame structure above relates to the entire upstream and not necessarily to the transmission from a single CM. The codes are resources that are allocated to CMs over each S-CDMA frame. The assignment of codes to CMs is performed by the framer as it assigns a burst of symbols a particular order in the two-dimensional matrix of codes and time. This symbol sequencing is described in detail in clause 6.2.12.
+
+#### **J.6.2.11.2.1 Mini-slot numbering parameters in UCD**
+
+Refer to clause 6.2.11.2.1.
+
+#### **J.6.2.11.2.2 Mini-slot numbering examples**
+
+Refer to clause 6.2.11.2.2.
+
+#### **J.6.2.11.3 Transmission time**
+
+Refer to clause 6.2.11.3.
+
+#### **J.6.2.11.4 Latency considerations**
+
+S-CDMA frame timing is derived directly from (is phase-locked to) the 9.216-MHz CMTS master clock. Based on the allowable signalling rates and the fact that there are 128 signalling periods in a spreading interval, the S-CDMA frame time MUST always be a multiple of 27.7 µs.
+
+Selecting the number of spreading intervals per frame and the signalling rate therefore exactly define the S-CDMA frame duration. As a specific example, a burst profile defined with 10 spreading intervals per frame with a signalling rate of 2.304 Mbaud would result in a frame duration of 555.5 µs.
+
+The amount of additional upstream latency added by the use of S-CDMA mode is approximately one S-CDMA frame with the exact value described in clause 6.2.17.
+
+#### **J.6.2.11.5 Spreader-off bursts for maintenance on S-CDMA channel**
+
+Refer to clause 6.2.11.5.
+
+#### **J.6.2.12 S-CDMA framer**
+
+Refer to clause 6.2.12.
+
+#### **J.6.2.13 Symbol mapping**
+
+Refer to clause 6.2.13.
+
+#### **J.6.2.14 S-CDMA spreader**
+
+Refer to clause 6.2.14.
+
+#### **J.6.2.15 Transmit pre-equalizer**
+
+Refer to clause 6.2.15.
+
+#### J.6.2.16 Spectral shaping
+
+The upstream transmitter MUST approximate a Nyquist square-root raised-cosine pulse-shaping filter with roll-off factor  $\alpha = 0.25$ . The  $-30$  dB transmitted bandwidth MUST NOT exceed the channel width values in Table J.6-1. The channel width values are given analytically by:
+
+$$\text{ChannelWidth} = \text{ModulationRate} \times (1 + \alpha)$$
+
+The occupied spectrum MUST NOT exceed the channel widths shown in Table J.6-1.
+
+**Table J.6-1 – Maximum channel width**
+
+| Modulation rate (kHz) | Channel width (kHz) | Recommended channel spacing (kHz) |
+|-----------------------|---------------------|-----------------------------------|
+| 144                   | 180                 | 187.5                             |
+| 288                   | 360                 | 375                               |
+| 576                   | 720                 | 750                               |
+| 1152                  | 1440                | 1500                              |
+| 2304                  | 2880                | 3000                              |
+| 4608                  | 5760                | 6000                              |
+
+##### J.6.2.16.1 Upstream frequency agility and range
+
+The upstream PMD sublayer MUST support operation over the frequency range of 10-55 MHz edge to edge.
+
+Offset frequency resolution MUST be supported having a range of  $\pm 32$  kHz (increment 1 Hz; implement within  $\pm 10$  Hz).
+
+##### J.6.2.16.2 Spectrum format
+
+Refer to clause 6.2.16.2.
+
+#### J.6.2.17 Relative processing delays
+
+The CM MAP processing delay is the time provided between arrival of the last bit of a MAP message at a CM and the effectiveness of this MAP. During this time, the CM should process the MAP message and fill its interleavers (or its framer, in S-CDMA mode) with encoded data. The CMTS MUST transmit the MAP message early enough to allow the CM MAP processing delay specified below.
+
+The CM MAP processing delay,  $D_p$ , is given by the equations:
+
+$$D_p = 200 + \frac{M}{4.608} \mu\text{s},$$
+
+$$M = \begin{cases} I_r N_r, & I_r \neq 0 \\ B_r, & I_r = 0 \end{cases}$$
+
+where  $M$  is the number of elements in the CM interleavers (in the case of TDMA), or framer (in the case of S-CDMA). In DOCS 1.x mode,  $M = 0$ . Note that in the above equations, the values for  $B_r$ , and  $I_r \times N_r$ , are taken to be the maximum from all of the specified burst types in a particular UCD.
+
+In S-CDMA mode,  $M = 128 (K + 1)$ , where  $K$  is the number of spreading intervals per frame. This is the time required for processing an S-CDMA frame plus an extra spreading interval. For
+
+example, in the case of  $K = 32$ , which corresponds to the maximum framer size, the CM MAP processing time is 1117  $\mu\text{s}$ , assuming a modulation rate of 4.608 MHz.
+
+NOTE 1 – The CM MAP processing delay does not include downstream FEC de-interleaving delay.
+
+NOTE 2 – The "effectiveness of the MAP" relates to the beginning of the burst frame at the RF output of the CM. In the S-CDMA mode, "effectiveness of the MAP" relates to the beginning (at the RF output of the CM) of the first spreading interval of the S-CDMA frame which contains the burst.
+
+#### J.6.2.18 Transmit power requirements
+
+The CM MUST support varying the amount of transmit power. Requirements are presented for:
+
+- 1) range of reported transmit power;
+- 2) step size of power commands;
+- 3) step size accuracy (actual change in output power compared to commanded change); and
+- 4) absolute accuracy of CM output power.
+
+The protocol by which power adjustments are performed is defined in clause 11.2.4, "ranging and automatic adjustments". Such adjustments by the CM MUST be within the ranges of tolerances described below. A CM MUST confirm that the transmit power limits are met after a RNG-RSP is received or after a UCD change.
+
+Transmit power is defined as the average RF power in the occupied bandwidth (channel width) transmitted in the data symbols of a burst, assuming equally likely QAM symbols, measured at the F-connector of the CM.
+
+Maximum and minimum transmit power level requirements refer to the CM's target transmit power level, defined as the CM's estimate of its actual transmit power. The actual transmitted power MUST be within  $\pm 2$  dB of the target power. The target transmit power MUST be variable over the range specified in Table J.6-4.
+
+Transmit power, as reported by the CM in the MIB, is referenced to the 64QAM constellation. When transmitting with other constellations, a slightly different transmit power will result, depending on the constellation gain in Table J.6-2 (see clause 6.2.13). As an example, if the reported power is 90 dB $\mu\text{V}$ , 64QAM will be transmitted with a target power of 90 dB $\mu\text{V}$ , while QPSK will be transmitted with 88.82 dB $\mu\text{V}$ .
+
+**Table J.6-2 – Constellation gains and power limits**
+
+| Constellation | Constellation gain $G_{\text{const}}$ relative to 64QAM (dB) | $P_{\text{min}}$ (dB $\mu\text{V}$ ) | $P_{\text{max}}$ (dB $\mu\text{V}$ ) TDMA | $P_{\text{max}}$ (dB $\mu\text{V}$ ) S-CDMA | $P_{\text{min}}$ (dB $\mu\text{V}$ ) | $P_{\text{max}}$ (dB $\mu\text{V}$ ) TDMA | $P_{\text{max}}$ (dB $\mu\text{V}$ ) S-CDMA |
+|---------------|--------------------------------------------------------------|--------------------------------------|-------------------------------------------|---------------------------------------------|--------------------------------------|-------------------------------------------|---------------------------------------------|
+| QPSK          | -1.18                                                        | 68                                   | 118                                       | 113                                         | 69.18                                | 119.18                                    | 114.18                                      |
+| 8QAM          | -0.21                                                        | 68                                   | 115                                       | 113                                         | 68.21                                | 115.21                                    | 113.21                                      |
+| 16QAM         | -0.21                                                        | 68                                   | 115                                       | 113                                         | 68.21                                | 115.21                                    | 113.21                                      |
+| 32QAM         | 0.00                                                         | 68                                   | 114                                       | 113                                         | 68.00                                | 114.00                                    | 113.00                                      |
+| 64QAM         | 0.00                                                         | 68                                   | 114                                       | 113                                         | 68.00                                | 114.00                                    | 113.00                                      |
+| 128QAM        | 0.05                                                         | 68                                   | N/A                                       | 113                                         | 67.95                                | N/A                                       | 112.95                                      |
+
+The actual transmitted power within a burst MUST be constant to within 0.1 dB peak to peak. This excludes the amplitude variation theoretically present due to QAM amplitude modulation, pulse shaping, pre-equalization and, for S-CDMA, spreading and varying number of allocated codes.
+
+### J.6.2.18.1 TDMA transmit power calculations
+
+In TDMA mode, the CM determines its target transmit power  $P_t$  as follows. Define:
+
+$P_r$  = Reported power level (dB $\mu$ V) of CM in MIB (refers to 64QAM constellation)
+
+$\Delta P$  = Power level adjustment (dB); for example, as commanded in ranging response message
+
+$G_{const}$  = Constellation gain (dB) relative to 64QAM constellation (see Table J.6-2)
+
+$P_{min}$  = Minimum target transmit power permitted for the CM per clause 6.2.21.1 (see Table J.6-2)
+
+$P_{max}$  = Maximum target transmit power permitted for the CM per clause 6.2.21.1 (see Table J.6-2)
+
+$P_{hi}$  =  $\min(P_{max} - G_{const})$  over all burst profiles used by the CM (see Table J.6-2)
+
+$P_{low}$  =  $\max(P_{max} - G_{const})$  over all burst profiles used by the CM (see Table J.6-2)
+
+$P_t$  = Target transmit power level (dB $\mu$ V) of CM (actual transmitted power as estimated by CM)
+
+The CM updates its reported power by the following steps:
+
+- 1)  $P_r = P_r + \Delta P$  //Add power level adjustment to reported power level
+- 2)  $P_r = \min[P_r, P_{hi}]$  //Clip at max power limit
+- 3)  $P_r = \max[P_r, P_{low}]$  //Clip at min power limit
+
+The CM then transmits with target power  $P_t = P_r + G_{const}$ , i.e., the reported power plus the constellation gain.
+
+Usually, the reported power level is a relatively constant quantity, while the transmitted power level varies dynamically as different burst profiles, with different constellation gains, are transmitted. A CM's target transmit power MUST never be below  $P_{min}$ , or above  $P_{max}$ . This implies that, in some cases, the extreme transmit power levels (e.g., 118 dB $\mu$ V for QPSK and 68 dB $\mu$ V) may not be permitted if burst profiles with multiple constellations are active. Also, if only QPSK is used, the reported power may be greater than 118 dB $\mu$ V, although the target transmit power will not exceed 118 dB $\mu$ V.
+
+For example, if only QPSK and 64QAM burst profiles are active,  $P_{hi} = 114$  dB $\mu$ V and  $P_{low} = 69.2$  dB $\mu$ V. The maximum permitted QPSK transmitted power is  $114 - 1.2 = 112.8$  dB $\mu$ V, the minimum QPSK power is  $69.2 - 1.2 = 68$  dB $\mu$ V, the maximum 64QAM power is 114 dB $\mu$ V, and the minimum 64QAM power is 69.2 dB $\mu$ V.
+
+### J.6.2.18.2 S-CDMA transmit power calculations
+
+In S-CDMA mode, the CM determines its target transmit power  $P_t$  as follows. Define:
+
+$P_{hi}$  =  $\min[P_{max} - G_{const}]$  over all burst profiles used by the CM (see Table J.6-2)
+
+$P_{low}$  =  $\max[P_{min} - G_{const}] + 10 \log(\text{number\_active\_codes} / \text{number\_of\_codes\_per\_mini-slot})$  where the maximum is over all burst profiles used by the CM (see Table J.6-2)
+
+The CM updates its reported power by the following steps:
+
+- 1)  $P_r = P_{min} + \Delta P$  //Add power level adjustment to reported power level
+- 2)  $P_r = \min[P_r, P_{hi}]$  //Clip at max power limit
+- 3)  $P_r = \max[P_r, P_{low}]$  //Clip at min power limit
+
+In a spreader-on frame, the CM then transmits each code  $i$  with target power
+
+$$P_{t,i} = P_r + G_{const,i} - 10 \log(\text{number\_active\_codes})$$
+
+i.e., the reported power plus the constellation gain  $G_{const,i}$  of that code, less a factor taking into account the number of active codes. The total transmit power  $P_t$  in a frame is the sum of the individual transmit powers  $P_{t,i}$  of each code, where the sum is performed using absolute power quantities (non-dB domain).
+
+In a spreader-off frame, the CM target transmit power is  $P_t = P_r + G_{const}$ .
+
+The transmitted power level varies dynamically as the number of allocated codes varies, and as different burst profiles, with different constellation gains, are transmitted. A CM's target transmit power MUST never be below  $P_{min}$  or above  $P_{max}$  including over all numbers of allocated codes and all burst profiles. This implies that, in some cases, the extreme transmit power levels (e.g., 68 and 113 dB $\mu$ V) may not be permitted. Also if, for example, only QPSK is used, the reported power may be greater than 113 dB $\mu$ V, although the target transmit power will not exceed 113 dB $\mu$ V.
+
+If, for example, QPSK and 64QAM burst profiles are active,  $P_{hi} = 113$  dB $\mu$ V and  $P_{low} = 69.2$  dB $\mu$ V. The maximum permitted QPSK transmitted power is  $113 - 1.2 = 111.8$  dB $\mu$ V when all active codes are transmitted, the minimum QPSK power is  $69.2 - 1.2 = 68$  dB $\mu$ V when one mini-slot is transmitted, the maximum 64QAM power is 113 dB $\mu$ V when all active codes are transmitted, and the minimum 64QAM power is 69.2 dB $\mu$ V with one mini-slot transmitted. The minimum QPSK power permitted while transmitting, for example, 2 mini-slots is 71 dB $\mu$ V, and the minimum 64QAM power permitted while transmitting 2 mini-slots is 72.2 dB $\mu$ V.
+
+The CM needs to implement some form of clipping on the transmitted waveform at the higher output powers in order to prevent peak to average ratio (PAR) issues.
+
+The power received at the CMTS in a spreader-on frame will sometimes be less than the nominal power of a spreader-off frame because of such factors as:
+
+- 1) broadcast opportunities not used by any CM;
+- 2) unicast grants not used by one or more CMs; or
+- 3) mini-slots assigned to the NULL SID.
+
+### J.6.2.18.3 Transmit power step size
+
+Refer to clause 6.2.18.3.
+
+### J.6.2.19 Burst profiles
+
+The transmission characteristics are separated into three portions:
+
+- a) channel parameters;
+- b) burst profile attributes; and
+- c) user-unique parameters.
+
+The channel parameters include:
+
+- i) the modulation rate (six rates from 144 ksymb/s to 4.608 Msymb/s in octave steps);
+- ii) the centre frequency (Hz);
+- iii) the 1536-bit preamble superstring; and
+- iv) the S-CDMA channel parameters.
+
+The channel parameters are further described in Table 8-18; these characteristics are shared by all users on a given channel. The burst profile attributes are listed in Table J.6-3 and are further described in Table 8-19; these parameters are the shared attributes corresponding to a burst type. The user-unique parameters may vary for each user even when using the same burst type on the same channel as another user (for example, power level), and are listed in Table J.6-4.
+
+The CM MUST generate each burst at the appropriate time as conveyed in the mini-slot grants provided by the CMTS MAPs (see clause 8.3.4).
+
+The CM MUST support all burst profiles commanded by the CMTS via the burst descriptors in the UCD (see clause 8.3.3), and subsequently assigned for transmission in a MAP (see clause 8.3.4).
+
+**Table J.6-3 – Burst profile attributes**
+
+| <b>Burst profile attributes</b>                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | <b>Configuration settings</b>                                                        |
+|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------|
+| Modulation                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | QPSK, 8QAM, 16QAM, 32QAM, 64QAM, 128QAM (TCM only)                                   |
+| Differential encoding                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | On/off                                                                               |
+| TCM encoding                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | On/off                                                                               |
+| Preamble length                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 0 to 1536 bits (see clause J.6.2.9)                                                  |
+| Preamble value offset                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | 0 to 1534                                                                            |
+| R-S FEC error correction (T)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 0 to 16 (0 implies no R-S FEC. The number of codeword parity bytes is $2 \times T$ ) |
+| R-S FEC codeword information bytes (k)                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | Fixed: 16 to 253 (assuming R-S FEC on)<br>Shortened: 16 to 253 (assuming FEC on)     |
+| Scrambler seed                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 15 bits                                                                              |
+| Maximum burst length (mini-slots) <sup>a)</sup>                                                                                                                                                                                                                                                                                                                                                                                                                                                             | 0 to 255                                                                             |
+| Guard time                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | 5 to 255 modulation intervals<br>1 for S-CDMA channels                               |
+| Last codeword length                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        | Fixed, shortened                                                                     |
+| Scrambler on/off                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | On/off                                                                               |
+| Byte interleaver depth ( $I_r$ ) <sup>b)</sup>                                                                                                                                                                                                                                                                                                                                                                                                                                                              | 0 to floor ( $2048/N_r$ ) <sup>c)</sup>                                              |
+| Byte interleaver block size ( $B_r$ ) <sup>d)</sup>                                                                                                                                                                                                                                                                                                                                                                                                                                                         | $2 \times N_r$ to 2048                                                               |
+| S-CDMA spreader <sup>e)</sup>                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | On/off                                                                               |
+| S-CDMA codes per subframe <sup>e)</sup>                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | 1 to 128                                                                             |
+| S-CDMA interleaver step <sup>e)</sup>                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | 1 to (spreading intervals per frame – 1)                                             |
+| <sup>a)</sup> A burst length of 0 mini-slots in the channel profile means that the burst length is variable on that channel for that burst type. The burst length, while not fixed, is granted explicitly by the CMTS to the CM in the MAP.<br><sup>b)</sup> If depth = 1, no interleaving; if depth = 0, dynamic mode.<br><sup>c)</sup> $N_r$ is the R-S codeword size: $k + 2T$ as defined in clause 6.2.6.1.<br><sup>d)</sup> Used only in dynamic mode.<br><sup>e)</sup> Used only for S-CDMA channels. |                                                                                      |
+
+**Table J.6-4 – User-unique burst parameters**
+
+| User-unique parameter                                                                                                                                                                          | Configuration settings                                                                                                                                                                           |
+|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Power level                                                                                                                                                                                    | TDMA:<br>+68 to +114 dBμV (32QAM, 64QAM)<br>+68 to +115 dBμV (8QAM, 16QAM)<br>+68 to +118 dBμV (QPSK)<br>S-CDMA:<br>+68 to +113 dBμV (all modulations)<br>1-dB steps                             |
+| Offset frequency <sup>a)</sup>                                                                                                                                                                 | Range = ±32 kHz; increment = 1 Hz; implement within ±10 Hz                                                                                                                                       |
+| Ranging offset                                                                                                                                                                                 | Integer part: 0 to (2 <sup>16</sup> –1), increments of 6.94 <sub>4</sub> μs/64<br>Fractional part: unsigned 8-bit fractional extension, units of 6.94 <sub>4</sub> μs/(64 × 256) = 0.42385525 ns |
+| Burst length (mini-slots) if variable on this channel (changes burst-to-burst)                                                                                                                 | 1 to 255 mini-slots                                                                                                                                                                              |
+| Transmit equalizer coefficients                                                                                                                                                                | Up to 64 coefficients; 4 bytes per coefficient: 2 real, 2 imaginary                                                                                                                              |
+| <sup>a)</sup> Values in this table apply for this given channel and modulation rate.<br>NOTE – Underlined digit represents an infinite series of the same digit: 6.94 <sub>4</sub> = 6.9444... |                                                                                                                                                                                                  |
+
+The CM MUST implement the offset frequency to within ±10 Hz.
+
+#### J.6.2.19.1 Ranging offset
+
+Ranging offset is the delay correction applied by the CM to the CMTS upstream frame time derived at the CM. It is an advancement equal to roughly the round-trip delay of the CM from the CMTS, and is needed to synchronize upstream transmissions in the TDMA and S-CDMA schemes. The CMTS MUST provide feedback correction for this offset to the CM, based on reception of one or more successfully received bursts (i.e., satisfactory result from each technique employed: error correction and/or CRC), with resolution of 1/16384 of the frame tick increment (6.94<sub>4</sub> μs/(64 × 256) = 0.42385525 ns). The CMTS sends adjustments to the CM, where a negative value implies the ranging offset is to be decreased, resulting in later times of transmission at the CM.
+
+For TDMA channels the CM MUST implement the correction with resolution of at most 1 symbol duration (of the symbol rate in use for a given burst), and (other than a fixed bias) with accuracy within ±0.25 μs plus ±1/2 symbol owing to resolution. As an example, for the maximum symbol rate of 4608 ksymb/s, the corresponding symbol period would be 217 ns, the corresponding maximum resolution for the timing correction MUST be 217 ns, and the corresponding minimum accuracy MUST be ±359 ns. The accuracy of CM burst timing of ±0.25 μs plus ±1/2 symbol is relative to the mini-slot boundaries derivable at the CM based on an ideal processing of the timestamp signals received from the CMTS.
+
+For S-CDMA channels, the CM MUST implement the ranging offset correction to within ±0.01 of the nominal chip period. As an example, for the maximum chip rate of 4608 kHz, the corresponding maximum resolution for the timing correction would be 217 ns × (±0.01) or roughly ±2 ns.
+
+#### J.6.2.19.2 TDMA reconfiguration times
+
+Refer to clause 6.2.19.2.
+
+#### J.6.2.19.3 S-CDMA reconfiguration times
+
+Refer to clause 6.2.19.3.
+
+#### J.6.2.20 Burst timing convention
+
+Refer to clause 6.2.20.
+
+#### J.6.2.21 Fidelity requirements
+
+The following requirements assume that any pre-equalization is disabled unless otherwise noted.
+
+##### J.6.2.21.1 Spurious emissions
+
+The spurious emissions MUST NOT exceed the values shown in Table J.6-5.
+
+**Table J.6-5 – Spurious emissions**
+
+| Frequency                                                                                                                    | Active Period                                                                                        | Inactive Period                                                                                   |
+|------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------|
+| 10 to 55 MHz, inband                                                                                                         | Less than $-40 \text{ dBc}^{\text{b) c)}}$                                                           | Less than the greater of $-72 \text{ dBc}^{\text{2,4}}$ or $+1 \text{ dB}\mu\text{V}^{\text{d)}}$ |
+| 10 to 55 MHz, outband including adjacent band, carrier-related band and other noise powers within 10 to 55 MHz <sup>a)</sup> | Less than $-45 \text{ dBc}^{\text{b) c)}}$                                                           |                                                                                                   |
+| 55 to 70 MHz                                                                                                                 | Less than the greater of $-45 \text{ dBc}^{\text{b) c)}}$ or $+35 \text{ dB}\mu\text{V}^{\text{e)}}$ | Less than $+35 \text{ dB}\mu\text{V}^{\text{e)}}$                                                 |
+| 70 to 90 MHz                                                                                                                 | Less than $+35 \text{ dB}\mu\text{V}^{\text{e)}}$                                                    | Less than $+25 \text{ dB}\mu\text{V}^{\text{e)}}$                                                 |
+| 90 to 770 MHz                                                                                                                | Less than $+25 \text{ dB}\mu\text{V}^{\text{e)}}$                                                    |                                                                                                   |
+
+<sup>a)</sup> The out-of-band spurious emissions are measured starting from the neighbouring  $-3 \text{ dB}$  response frequencies of the adjacent channels at symbol rate  $R$ . To maintain 6-MHz upstream channelization, this frequency offset is given as the transmitted channel centre frequency  $\pm \Delta f$ , where  $\Delta f = [(1 + 2\alpha)/2 + 240'000/4'608'000] \times R \text{ Hz} = 0.8 R \text{ Hz}$  for roll-off factor  $\alpha = 0.25$ .
+
+<sup>b)</sup> The modulated carrier power is measured within the occupied bandwidth of the data signal, which is equal to 1.25 times the upstream transmission symbol rate.
+
+<sup>c)</sup> The total spurious emissions power is measured within the Nyquist bandwidth of the transmitted signal, which is equal to the upstream transmission symbol rate.
+
+<sup>d)</sup> The total spurious emissions power is measured within the Nyquist bandwidth of the lowest transmitted symbol rate, which is equal to 144 kHz. For any other symbol rate  $B \text{ Hz}$ , this value is adjusted by  $10 \log (B/144,000) \text{ dB}$ .
+
+<sup>e)</sup> The total spurious emissions power is measured within the NTSC bandwidth, which is equal to 4.0 MHz.
+
+##### J.6.2.21.1.1 Adjacent channel spurious emissions
+
+Clause 6.2.21.1.1 is not applicable to Annex J.
+
+##### J.6.2.21.1.2 Spurious emissions in 5 to 42 MHz
+
+Clause 6.2.21.1.2 is not applicable to Annex J.
+
+##### J.6.2.21.2 Spurious emissions during burst on/off transients
+
+Clause 6.2.21.2 is not applicable to Annex J.
+
+##### J.6.2.21.3 Modulation error ratio (MER)
+
+MER measures the cluster variance caused by the transmit waveform. It includes the effects of ISI, spurious, phase noise and all other transmitter degradations.
+
+### J.6.2.21.3.1 Definitions
+
+**Symbol MER:**  $MER_{\text{symb}}$  is defined as follows for TDMA or S-CDMA symbols. The transmitted RF waveform (after appropriate downconversion) is applied to the ideal receive symbol matched filter and is sampled once per symbol. For TDMA, the matched filter is a square-root raised cosine filter with  $\alpha = 0.25$ . For S-CDMA, the matched filter is a square-root raised cosine filter with  $\alpha = 0.25$ , convolved with the time-reversed spreading code sequence (in this convolution, the spreading code sequence is expressed as a weighted impulse train spaced at the chip period). No external noise (AWGN) is added to the signal. The carrier frequency offset, carrier phase offset, symbol timing and gain may be adjusted during each burst to maximize  $MER_{\text{symb}}$ . Equalization of the received waveform is not permitted. For cases where the CM transmit equalizer is ON, the transmit equalizer coefficients may be adjusted to maximize  $MER_{\text{symb}}$ .  $MER_{\text{symb}}$  is defined at the F connector of the CM, except that when an echo channel is inserted,  $MER_{\text{symb}}$  is defined at the output of the echo channel.  $MER_{\text{symb}}$  is computed by the formula:
+
+$$MER_{\text{symb}}(\text{dB}) = 10 \times \log_{10} \left( \frac{E_{av}}{\frac{1}{N} \sum_{j=1}^N |e_j|^2} \right)$$
+
+where:
+
+$E_{av}$  is the average constellation energy for equally likely symbols (see clause J.6.2.13 and Figure 6-18)
+
+$N$  is the number of symbols averaged
+
+$e_j$  is the error vector from the  $j$ th received symbol to the ideal transmitted QAM symbol on the grid of Figure 6-18
+
+For S-CDMA,  $MER_{\text{symb}}$  is averaged over all active codes.
+
+**MER of composite chips:**  $MER_{\text{chip}}$  is specified for composite S-CDMA chips to ensure that high SNR is maintained, especially for a small number of allocated codes, to prevent noise funnelling effects when many modems transmit simultaneously. A composite S-CDMA chip is defined as the output of the spreader during one chip interval, that is, an element of the transmission vector  $\overline{P}_k$  defined in clause J.6.2.14, "S-CDMA spreader".
+
+$MER_{\text{chip}}$  is defined as follows. The transmitted RF waveform (after appropriate downconversion) is applied to the ideal receive chip matched filter and is sampled once per chip. The matched filter is a square-root raised cosine filter with  $\alpha = 0.25$ . No external noise (AWGN) is added to the signal. The carrier frequency offset, carrier phase offset, timing and gain may be adjusted during each burst to maximize  $MER_{\text{chip}}$ . Equalization of the received waveform is not permitted. For cases where the CM transmit equalizer is ON, the transmit equalizer coefficients may be adjusted to maximize  $MER_{\text{chip}}$ .  $MER_{\text{chip}}$  is defined at the F connector of the CM.  $MER_{\text{chip}}$  is computed by the formula:
+
+$$MER_{\text{chip}}(\text{dB}) = 10 \times \log_{10} \left( \frac{\sum_{j=1}^N |p_j|^2}{\sum_{j=1}^N |p_j - r_j|^2} \right)$$
+
+where:
+
+$p_j$  is the  $j$ th ideal transmitted composite chip
+
+$r_j$  is the  $j$ th received composite chip
+
+$N$  is the number of composite chips observed
+
+#### **J.6.2.21.3.2 Requirements**
+
+Unless otherwise stated, the MER MUST meet or exceed the following limits over the full transmit power range of Table J.6-4 for each modulation, each modulation rate, and over the full carrier frequency range, and for S-CDMA, over any valid number of active and allocated codes. The 10-55 MHz carrier frequency range refers more precisely to  $[10 \text{ MHz} + \text{modulation rate} \times 1.25/2]$  to  $[55 \text{ MHz} - \text{modulation rate} \times 1.25/2]$ . At the break points between regions, the higher MER specification applies.
+
+##### **Case 1: Flat channel, transmit equalization OFF**
+
+Case 1a: for modulation rates 2.304 MHz and below:
+
+$\text{MER}_{\text{symb}} \geq 30 \text{ dB}$  over 20 to 41 MHz carrier frequency.
+
+$\text{MER}_{\text{symb}} \geq 27 \text{ dB}$  over 15 to 20 MHz and 41 to 47 MHz carrier frequency.
+
+$\text{MER}_{\text{symb}} \geq 23 \text{ dB}$  over 10 to 15 MHz and 47 to 55 MHz carrier frequency.
+
+Case 1b: for modulation rate 4.608 MHz:
+
+$\text{MER}_{\text{symb}} \geq 27 \text{ dB}$  over 20 to 41 MHz carrier frequency.
+
+$\text{MER}_{\text{symb}} \geq 24 \text{ dB}$  over 15 to 20 MHz and 41 to 47 MHz carrier frequency.
+
+$\text{MER}_{\text{symb}} \geq 20 \text{ dB}$  over 10 to 20 MHz and 47 to 55 MHz carrier frequency.
+
+##### **Case 2: Flat channel, transmit equalization ON**
+
+Case 2a: For TDMA/QPSK,  $\text{MER}_{\text{symb}} \geq 30 \text{ dB}$ .
+
+Case 2b: For S-CDMA and all TDMA modulations except QPSK,  $\text{MER}_{\text{symb}} \geq 35 \text{ dB}$ .
+
+Case 2c: For S-CDMA,  $\text{MER}_{\text{chip}} \geq 33 \text{ dB}$ .
+
+##### **Case 3: Echo channel, transmit equalization ON**
+
+Case 3a: In the presence of a single echo selected from the channel micro-reflections defined in Figure J.4-1, the measured  $\text{MER}_{\text{symb}}$  MUST be  $\geq 30 \text{ dB}$  for TDMA/QPSK, and  $\geq 33 \text{ dB}$  for S-CDMA and all TDMA modulations except QPSK.
+
+Case 3b: In the presence of two or three of the echoes defined in Figure J.4-1 (at most one of each specified magnitude and delay), the measured  $\text{MER}_{\text{symb}}$  MUST be  $\geq 29 \text{ dB}$ .
+
+The CMTS MUST provide a test mode in which it:
+
+- accepts equalizer coefficients via an external interface, e.g., Ethernet;
+- sends the coefficients to the CM's pre-equalizer via ranging response message (both set and convolve modes);
+- does not adjust the CM's frequency, timing or power.
+
+#### **J.6.2.21.4 Filter distortion**
+
+Refer to clause 6.2.21.4.
+
+#### **J.6.2.21.5 Carrier phase noise**
+
+Refer to clause 6.2.21.5.
+
+#### **J.6.2.21.6 Channel frequency accuracy**
+
+Refer to clause 6.2.21.6.
+
+#### J.6.2.21.7 Modulation rate accuracy
+
+Refer to clause 6.2.21.7.
+
+#### J.6.2.21.8 Modulation timing jitter
+
+Refer to clause 6.2.21.8.
+
+#### J.6.2.22 Upstream demodulator input power characteristics
+
+The maximum total input power to the upstream demodulator MUST NOT exceed 95 dB $\mu$ V in the 10-55 MHz frequency range of operation.
+
+The intended received power in each carrier MUST be within the values shown in Table J.6-6.
+
+**Table J.6-6 – Maximum range of commanded nominal receive power in each carrier**
+
+| Modulation rate (kHz) | Maximum range (dB $\mu$ V) |
+|-----------------------|----------------------------|
+| 144                   | +44 to +72                 |
+| 288                   | +47 to +75                 |
+| 576                   | +50 to +78                 |
+| 1152                  | +53 to +81                 |
+| 2304                  | +56 to +84                 |
+| 4608                  | +59 to +87                 |
+
+The demodulator MUST operate within its defined performance specifications with received bursts within  $\pm 6$  dB of the nominal commanded received power.
+
+#### J.6.2.23 Upstream electrical output from the CM
+
+The CM MUST output an RF modulated signal with the characteristics delineated in Table J.6-7.
+
+**Table J.6-7 – Electrical output from the CM**
+
+| Parameter                 | Value                                                                                                                                                                                    |
+|---------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Frequency                 | 10 to 55 MHz edge to edge                                                                                                                                                                |
+| Level range (one channel) | TDMA:<br>+68 to +114 dB $\mu$ V (32QAM, 64QAM)<br>+68 to +115 dB $\mu$ V (8QAM, 16QAM)<br>+68 to +118 dB $\mu$ V (QPSK)<br>S-CDMA:<br>+68 to +113 dB $\mu$ V (all modulations of S-CDMA) |
+| Modulation type           | QPSK, 8QAM, 16QAM, 32QAM, 64QAM and 128QAM                                                                                                                                               |
+| Modulation rate (nominal) | TDMA: 144, 288, 576, 1152, 2304 and 4608 kHz<br>S-CDMA: 1152, 2304 and 4608 kHz                                                                                                          |
+| Bandwidth                 | TDMA: 187.5, 375, 750, 1500, 3000 and 6000 kHz<br>S-CDMA: 1500, 3000 and 6000 kHz                                                                                                        |
+| Output impedance          | 75 ohms                                                                                                                                                                                  |
+| Output return loss        | >6 dB (10-55 MHz)                                                                                                                                                                        |
+| Connector                 | F connector per [IEC 60169-24] (common with the input)                                                                                                                                   |
+
+### J.6.3 Downstream
+
+#### J.6.3.1 Downstream protocol
+
+The downstream PMD sublayer MUST conform to Annex C of [ITU-T J.83].
+
+#### J.6.3.2 Interleaving
+
+The interleave method for 64QAM MUST be compliant with Annex C of [ITU-T J.83]. The interleave method for 256QAM is equal to Annex C of [ITU-T J.83] except for interleave depth values. The interleave depth  $I = 12$  MUST be supported by the CM and CMTS. The CM and CMTS MAY support interleaver depths of  $I = 34$  or  $I = 204$ . Table J.6-8 shows the interleaver characteristics at 5.274 Msymb/s.
+
+**Table J.6-8 – Interleaver characteristics (@ 5.274 Msymb/s)**
+
+| <b>I<br/>(number of taps)</b> | <b>J<br/>(increment)</b> | <b>Burst protection<br/>64QAM/256QAM</b> | <b>Latency<br/>64QAM/256QAM</b> |
+|-------------------------------|--------------------------|------------------------------------------|---------------------------------|
+| 12                            | 17                       | 24 $\mu\text{s}$ /18 $\mu\text{s}$       | 0.57 ms/0.43 ms                 |
+| 34                            | 6                        | –/51 $\mu\text{s}$                       | –/1.28 ms                       |
+| 204                           | 1                        | –/300 $\mu\text{s}$                      | –/7.85 ms                       |
+
+#### J.6.3.3 Downstream frequency plan
+
+The downstream channel MUST support a 90 MHz to 770 MHz frequency range edge to edge.
+
+#### J.6.3.4 CMTS electrical output
+
+The transmission signal level at CMTS output connector MUST be adjustable over the range of +100 to +120 dB $\mu$ Vrms.
+
+##### J.6.3.4.1 Modulation method
+
+The modulation method MUST be 64QAM and 256QAM for downstream.
+
+##### J.6.3.4.2 Signal constellation diagram
+
+The signal constellation diagram and phase shift rule for 64QAM MUST be compliant with Annex C of [ITU-T J.83]. 256QAM signal constellation diagram MUST be compliant with Figure J.6-6, when the interleave depth  $I = 12$  is selected. In case that the interleaver depth  $I = 34$  or 204 is selected, the signal constellation diagram and phase shift rule MUST be as shown in Figure J.6-7.
+
+![Block diagram of the 256QAM mapping process. Six bits b0 through b5 are input to an 'IQ mapping' block. A differential encoding block takes Bk = b6 and Ak = b7(MSB) as inputs and produces Qk and Ik as outputs. These four signals (Ik, Qk, b0-b5) are then processed by the 'IQ mapping' block to produce the final I and Q outputs.](24ca424ca19ebeeafb6a9249dcd7bcfa_img.jpg)
+
+Block diagram of the 256QAM mapping process. Six bits b0 through b5 are input to an 'IQ mapping' block. A differential encoding block takes Bk = b6 and Ak = b7(MSB) as inputs and produces Qk and Ik as outputs. These four signals (Ik, Qk, b0-b5) are then processed by the 'IQ mapping' block to produce the final I and Q outputs.
+
+$$I_k = (A_k \oplus B_k) \cdot (A_k \oplus I_{k-1}) + (A_k \oplus B_k) \cdot (A_k \oplus Q_{k-1})$$
+
+$$Q_k = (A_k \oplus B_k) \cdot (B_k \oplus Q_{k-1}) + (A_k \oplus B_k) \cdot (B_k \oplus I_{k-1})$$
+
+![256QAM signal constellation diagram and phase shift rule. The diagram shows a grid of 256 points in the I-Q plane. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'. The grid is divided into four quadrants based on the values of Ik and Qk. The top-right quadrant is labeled 'Ik Qk = 00'. The other three quadrants show phase shifts: 'Ik Qk = 10' (Rotate 90 degrees), 'Ik Qk = 11' (Rotate 180 degrees), and 'Ik Qk = 01' (Rotate 270 degrees). The grid points are labeled with 6-bit binary values b5 b4 b3 b2 b1 b0. The diagram is signed 'J.122_FJ-6-6'.](723d2f8c4e582206a0929413e12c00fe_img.jpg)
+
+256QAM signal constellation diagram and phase shift rule. The diagram shows a grid of 256 points in the I-Q plane. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'. The grid is divided into four quadrants based on the values of Ik and Qk. The top-right quadrant is labeled 'Ik Qk = 00'. The other three quadrants show phase shifts: 'Ik Qk = 10' (Rotate 90 degrees), 'Ik Qk = 11' (Rotate 180 degrees), and 'Ik Qk = 01' (Rotate 270 degrees). The grid points are labeled with 6-bit binary values b5 b4 b3 b2 b1 b0. The diagram is signed 'J.122\_FJ-6-6'.
+
+Figure J.6-6 – 256QAM signal constellation diagram and phase shift rule (I = 12)
+
+![Figure J.6-7 – 256QAM signal constellation diagram and phase shift rule (I = 34 or 204). The diagram shows a 16x16 grid of 256 points in the I-Q plane. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'. The points are labeled with 6-bit binary sequences b5 b4 b3 b2 b1 b0. The origin is labeled Ik Qk = 00. The diagram also shows phase shift rules: Rotate 90 degrees (Ik Qk = 10), Rotate 180 degrees (Ik Qk = 11), Rotate 270 degrees (Ik Qk = 01). The diagram is labeled J.122_FJ-6-7.](b4869fe05a0f31bb206f729f5081d6a8_img.jpg)
+
+Figure J.6-7 – 256QAM signal constellation diagram and phase shift rule (I = 34 or 204). The diagram shows a 16x16 grid of 256 points in the I-Q plane. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'. The points are labeled with 6-bit binary sequences b5 b4 b3 b2 b1 b0. The origin is labeled Ik Qk = 00. The diagram also shows phase shift rules: Rotate 90 degrees (Ik Qk = 10), Rotate 180 degrees (Ik Qk = 11), Rotate 270 degrees (Ik Qk = 01). The diagram is labeled J.122\_FJ-6-7.
+
+**Figure J.6-7 – 256QAM signal constellation diagram and phase shift rule (I = 34 or 204)**
+
+#### J.6.3.4.3 Symbol rate, bandwidth and roll off
+
+The symbol rate MUST be 5.274 Msymb/s. Bandwidth MUST be 6 MHz. The roll-off factor MUST be  $\alpha = 0.13$ . Other parameters related to symbol rate, bandwidth and roll-off SHOULD be compliant with Annex C of [ITU-T J.83].
+
+#### J.6.3.4.4 Frame structure
+
+The frame structure SHOULD be compliant with Annex C of [ITU-T J.83].
+
+#### J.6.3.4.5 Error correction
+
+Error correction functionality SHOULD be considered for the noise environment in the cable television network. Code length and information byte length MUST be in accordance with Annex C of [ITU-T J.83].
+
+The original Reed-Solomon code is defined as follows:
+
+- Primitive polynomial:  $P(x) = x^8 + x^4 + x^3 + x^2 + 1$
+- Generator polynomial:  $G(x) = (x + \alpha^0)(x + \alpha^1) \cdots (x + \alpha^{2t-1})$
+
+where  $t$  is the error-correcting capability of a Reed-Solomon code and  $\alpha$  is 02H and one of roots of equation  $P(x) = 0$ .
+
+#### J.6.3.4.6 Randomization
+
+A randomization function MUST be provided. The generator polynomial MUST be compliant with Annex C of [ITU-T J.83].
+
+#### **J.6.3.4.7 Transmission signal level**
+
+The transmission signal level at the CMTS output connector MUST be adjustable over the range of +100 to +120 dB $\mu$ Vrms.
+
+#### **J.6.3.4.8 Transmission spurious level**
+
+Transmission spurious level at the CMTS output connector MUST be less than -55 dBc over the range of 90 MHz to 770 MHz.
+
+#### **J.6.3.4.9 Channel frequency accuracy**
+
+Channel frequency accuracy MUST be within  $\pm 20$  kHz over a temperature range of 0 to 40° C.
+
+#### **J.6.3.4.10 Symbol rate accuracy**
+
+Symbol rate accuracy MUST be within  $\pm 20$  ppm over a temperature range of 0 to 40° C.
+
+#### **J.6.3.4.11 Impedance, return loss and connector**
+
+Impedance, return loss and connector at the CMTS output and CMTS input MUST meet the requirements shown in Table J.6-9.
+
+**Table J.6-9 – Impedance, return loss and connector type**
+
+|             | <b>Impedance</b> | <b>Return loss</b>            | <b>Connector type</b> |
+|-------------|------------------|-------------------------------|-----------------------|
+| CMTS Output | 75 $\Omega$      | More than 14 dB<br>90-770 MHz | F-type, female        |
+| CMTS Input  | 75 $\Omega$      | More than 6 dB<br>10-55 MHz   | F- type, female       |
+
+#### **J.6.3.5 Downstream electrical input to CM**
+
+##### **J.6.3.5.1 Receiving signal level**
+
+CM MUST be able to operate at the level within a range of +45 to +75 dB $\mu$ Vrms for 64QAM, +51 to +81 dB $\mu$ Vrms for 256QAM at CM Input connector.
+
+##### **J.6.3.5.2 Impedance, return loss and connector**
+
+Impedance, return loss and connector at CM in/output MUST meet the requirements shown in Table J.6-10.
+
+**Table J.6-10 – Impedance, return loss and connector type**
+
+|              | <b>Impedance</b> | <b>Return loss</b>                     | <b>Connector type</b> |
+|--------------|------------------|----------------------------------------|-----------------------|
+| CM in/output | 75 $\Omega$      | More than 6 dB<br>10-55 and 90-770 MHz | F-type, female        |
+
+#### **J.6.3.6 CM BER performance**
+
+The bit-error-rate performance of a CM MUST be as described in this clause. The requirements apply to the I = 12, J = 17 mode of interleaving.
+
+##### **J.6.3.6.1 64QAM**
+
+###### **J.6.3.6.1.1 64QAM CM BER performance**
+
+Bit error rate MUST be less than  $10^{-8}$  at CNR (Nyquist bandwidth) of 26 dB $\text{rms}$  for 64QAM with error correction.
+
+#### **J.6.3.6.1.2 64QAM image rejection performance**
+
+Performance as described in clause J.6.3.6.1.1 MUST be met with an analogue or digital signal at +10 dBc in any portion of the RF band other than the adjacent channels.
+
+#### **J.6.3.6.1.3 64QAM adjacent channel performance**
+
+Performance as described in clause J.6.3.6.1.1 MUST be met with a digital signal at 0 dBc in the adjacent channels.
+
+Performance as described in clause J.6.3.6.1.1 MUST be met with an analogue signal at +10 dBc in the adjacent channels.
+
+Performance as described in clause J.6.3.6.1.1, with an additional 0.2-dB allowance, MUST be met with a digital signal at +10 dBc in the adjacent channels.
+
+#### **J.6.3.6.2 256QAM**
+
+##### **J.6.3.6.2.1 256QAM CM BER performance**
+
+Bit error rate MUST be less than  $10^{-8}$  at CNR (Nyquist bandwidth) of 33 dBrms for 256QAM with error correction.
+
+##### **J.6.3.6.2.2 256QAM image rejection performance**
+
+Performance as described in clause J.6.3.6.2.1 MUST be met with an analogue or digital signal at +10 dBc in any portion of the RF band other than the adjacent channels.
+
+##### **J.6.3.6.2.3 256QAM adjacent channel performance**
+
+Refer to clause J.4.4.
+
+#### **J.6.3.7 CMTS timestamp jitter**
+
+The CMTS timestamp jitter MUST be less than 500 ns peak-to-peak at the output of the downstream transmission convergence sublayer. This jitter is relative to an ideal downstream transmission convergence sublayer that transfers the MPEG packet data to the downstream physical media dependent sublayer with a perfectly continuous and smooth clock at the MPEG packet data rate. Downstream physical media dependent sublayer processing MUST NOT be considered in timestamp generation and transfer to the downstream physical media dependent sublayer.
+
+Thus, any two timestamps N1 and N2 ( $N2 > N1$ ) which were transferred to the downstream physical media dependent sublayer at times T1 and T2, respectively, must satisfy the following relationship:
+
+$$|(N2 - N1)/f_{\text{CMTS}} - (T2 - T1)| < 500 \times 10^{-9}$$
+
+In the equation, the value of  $(N2 - N1)$  is assumed to account for the effect of roll-over of the timebase counter, and T1 and T2 represent time in seconds.  $f_{\text{CMTS}}$  is the actual frequency of the CMTS master timebase and may include a fixed frequency offset from the nominal frequency of 9.216 MHz. This frequency offset is bounded by a requirement further below in this clause.
+
+The jitter includes inaccuracy in timestamp value and the jitter in all clocks. The 500 ns allocated for jitter at the downstream transmission convergence sublayer output MUST be reduced by any jitter that is introduced by the downstream physical media dependent sublayer.
+
+The CM is expected to meet the burst timing accuracy requirements in clause 6.2.19 when the timestamps contain this worst-case jitter.
+
+NOTE – Jitter is the error (i.e., measured) relative to the CMTS master clock (the CMTS master clock is the 9.216-MHz clock used for generating the timestamps).
+
+#### J.6.3.7.1 CMTS master clock jitter for asynchronous operation
+
+The CMTS 9.216-MHz master clock MUST have frequency accuracy of  $\leq \pm 5$  ppm, drift rate:  $\leq 10^{-8}$  per second, and edge jitter of:  $\leq 10$  ns peak-to-peak ( $\pm 5$  ns) over a temperature range of 0 to 40 degrees C up to ten years from date of manufacture<sup>30</sup>. (The drift rate and jitter requirements on the CMTS master clock implies that the duration of two adjacent segments of 9 216 000 cycles will be within 30 ns, due to 10-ns jitter on each segment's duration, and 10 ns due to frequency drift. Durations of other counter lengths also may be deduced: adjacent 9 216 000 segments,  $\leq 21$  ns; 9 216 000 length segments separated by one 92 160 000 cycle segment,  $\leq 30$  ns; adjacent 921 600 000 segments,  $\leq 120$  ns. The CMTS master clock MUST meet such test limits in 99% or more measurements.)
+
+#### J.6.3.7.2 CMTS master clock jitter for synchronous operation
+
+In addition to the requirements in clause 6.3.7.1, the 9.216-MHz CMTS master clock MUST meet the following double sideband phase noise requirements over the specified frequency ranges:
+
+- $< [-50 + 20 \times \log(f_{MC}/9.216)]$  dBc (i.e.,  $< 0.05$  ns RMS) 10 Hz to 100 Hz
+- $< [-58 + 20 \times \log(f_{MC}/9.216)]$  dBc (i.e.,  $< 0.02$  ns RMS) 100 Hz to 1 kHz
+- $< [-50 + 20 \times \log(f_{MC}/9.216)]$  dBc (i.e.,  $< 0.05$  ns RMS) 1 to 10 kHz
+- $< [-50 + 20 \times \log(f_{MC}/9.216)]$  dBc (i.e.,  $< 0.05$  ns RMS) 10 kHz to  $f_{MC}/2$
+
+where  $f_{MC}$  is the frequency of the measured master clock in MHz. The value of  $f_{MC}$  MUST be either an integral multiple or divisor of 9.216 MHz. For example, if a 18.432-MHz oscillator is used as the master clock frequency source, and there is no explicit 9.216-MHz clock to test, the 18.432-MHz clock may be used with  $f_{MC}$  equal to 18.432 in the above expressions.
+
+#### J.6.3.7.3 CMTS master clock frequency drift for synchronous operation
+
+Refer to clause 6.3.7.3.
+
+#### J.6.3.8 CMTS clock generation
+
+The CMTS has the following three options related to the synchronization of the CMTS master clock and the downstream symbol clock:
+
+- 1) not locked;
+- 2) downstream symbol clock locked to cmts master clock;
+- 3) CMTS master clock locked to downstream symbol clock.
+
+For S-CDMA operation, the master clock and the downstream symbol clock MUST be locked using either option 2 or 3.
+
+Let  $f_b'$  represent the rate of the downstream symbol clock which is locked to the CMTS master clock, and let  $f_m'$  represent the rate of the CMTS master clock locked to the downstream symbol clock. Let  $f_b$  represent the nominal specified downstream symbol rate, and let  $f_m$  represent the nominal CMTS master clock rate (9.216 MHz).
+
+With the downstream symbol clock locked to the CMTS master clock, the following equation MUST hold:
+
+$$f_b' = f_m \times M/N$$
+
+---
+
+<sup>30</sup> This Recommendation MAY also be met by synchronizing the CMTS master clock oscillator to an external frequency reference source. If this approach is used, the internal CMTS master clock MUST have frequency accuracy of  $\pm 20$  ppm over a temperature range of 0 to 40 degrees C up to ten years from date of manufacture when no frequency reference source is connected. The drift rate and edge jitter MUST be as specified above.
+
+With the CMTS master clock locked to the downstream symbol clock, the following equation MUST hold:
+
+$$f_m' = f_b \times N/M$$
+
+M and N MUST be unsigned integer values each representable in 16 bits (these are specified in the channel TLV parameters of the UCD). When the downstream symbol clock and the CMTS master clock are not locked together (sync mode = 0), the values of M and N are not valid and are ignored by the CM.
+
+The values of M and N MUST result in a value of  $f_b'$  or  $f_m'$ , which is not more than  $\pm 1$  ppm from its specified nominal value. Table J.6-11 lists the downstream modes of operation, their associated nominal symbol rates,  $f_b$ , example values for M and N, the resulting synchronized clock rates, and their offsets from their nominal values.
+
+**Table J.6-11 – Downstream symbol rates and example parameters for synchronization with the CMTS master clock**
+
+| Downstream mode  | Nominal specified symbol rate, $f_b$ (MHz) | M/N     | CMTS master clock rate, $f_m'$ (MHz) | Downstream symbol rate, $f_b'$ (MHz) | Offset from nominal |
+|------------------|--------------------------------------------|---------|--------------------------------------|--------------------------------------|---------------------|
+| 64QAM and 256QAM | 5.274                                      | 293/512 | 9.216                                | 5.274                                | 0 ppm               |
+
+### J.6.3.9 Downstream symbol clock jitter for synchronous operation
+
+The downstream symbol clock MUST meet the following double sideband phase noise requirements over the following frequency ranges:
+
+- $< [-53 + 20 \times \log(f_{DS}/5.274)]$  dBc (i.e.,  $< 0.07$  ns rms) 10 to 100 Hz
+- $< [-53 + 20 \times \log(f_{DS}/5.274)]$  dBc (i.e.,  $< 0.07$  ns rms) 100 Hz to 1 kHz
+- $< [-53 + 20 \times \log(f_{DS}/5.274)]$  dBc (i.e.,  $< 0.07$  ns rms) 1 to 10 kHz
+- $< [-36 + 20 \times \log(f_{DS}/5.274)]$  dBc (i.e.,  $< 0.5$  ns rms) 10 to 100 kHz
+- $< [-30 + 20 \times \log(f_{DS}/5.274)]$  dBc (i.e.,  $< 1$  ns rms) 100 kHz to ( $f_{DS}/2$ )
+
+where  $f_{DS}$  is the frequency of the measured clock in MHz. The value of  $f_{DS}$  MUST be an integral multiple or divisor of the downstream symbol clock. For example, an  $f_{DS} = 21.096$ -MHz clock may be measured if there is no explicit 5.274-MHz clock available.
+
+The CMTS MUST provide a test mode in which:
+
+- the downstream QAM symbol sequence is replaced with an alternating binary sequence (1, -1, 1, -1, 1, -1, ...) at nominal amplitude, on both I and Q;
+- the CMTS generates the downstream symbol clock from the 9.216-MHz reference clock as in normal synchronous operation.
+
+If an explicit downstream symbol clock that is capable of meeting the above phase noise requirements is available (e.g., a smooth clock without clock domain jitter), this test mode is not required.
+
+### J.6.3.10 CMTS downstream symbol clock drift for synchronous operation
+
+Refer to clause 6.3.10.
+
+## J.7 Downstream transmission convergence sublayer
+
+### J.7.1 Introduction
+
+In order to improve demodulation robustness, facilitate common receiving hardware for both video and data, and provide an opportunity for the possible future multiplexing of video and data over the PMD sublayer bitstream defined in clause 6, a sublayer is interposed between the downstream PMD sublayer and the data-over-cable MAC sublayer.
+
+The downstream bitstream is defined as a continuous series of 188-byte MPEG [ITU-T H.222.0] packets. These packets consist of a 4-byte header followed by 184 bytes of payload. The header identifies the payload as belonging to the data-over-cable MAC. Other values of the header may indicate other payloads. the mixture of MAC payloads and those of other services is optional and is controlled by the CMTS.
+
+Figure J.7-1 illustrates the interleaving of data-over-cable (DOC) MAC bytes with other digital information (digital video in the example shown).
+
+|                |                       |
+|----------------|-----------------------|
+| Header = DOC   | DOC MAC payload       |
+| Header = video | Digital video payload |
+| Header = video | Digital video payload |
+| Header = DOC   | DOC MAC payload       |
+| Header = video | Digital video payload |
+| Header = DOC   | DOC MAC payload       |
+| Header = video | Digital video payload |
+| Header = video | Digital video payload |
+| Header = video | Digital video payload |
+
+Figure J.7-1 – Example of interleaving MPEG packets in downstream
+
+### J.7.2 MPEG packet format
+
+Refer to clause 7.2.
+
+### J.7.3 MPEG header for DOCS data-over-cable
+
+Refer to clause 7.3.
+
+### J.7.4 MPEG payload for DOCS data-over-cable
+
+Refer to clause 7.4.
+
+### J.7.5 Interaction with the MAC sublayer
+
+Refer to clause 7.5.
+
+### J.7.6 Interaction with the physical layer
+
+The MPEG-2 packet stream MUST be encoded according to Annex C of [ITU-T J.83].
+
+### J.7.7 MPEG header synchronization and recovery
+
+Refer to clause 7.7.
+
+## J.8 Media access control specification
+
+Refer to clause 8, except for the following changes:
+
+- Time tick 6.25 µs MUST change to 6.94 µs.
+- Master clock 10.24 MHz MUST change to 9.216 MHz.
+- Base rate 160 KHz MUST change to 144 KHz.
+
+#### J.8.3.20.1.2.3 Downstream symbol rate
+
+This TLV specifies the symbol rate that is used on the new downstream channel.
+
+| Subtype | Length | Value                                                                                                 |
+|---------|--------|-------------------------------------------------------------------------------------------------------|
+| 2.3     | 1      | 0: 5.056941 Msymb/s<br>1: 5.360537 Msymb/s<br>2: 6.952 Msymb/s<br>3: 5.274 Msymb/s<br>4-255: reserved |
+
+The CMTS SHOULD include this sub-TLV. The CM SHOULD observe this sub-TLV.
+
+### J.9 Media access control protocol operation
+
+#### J.9.3.4 Timing units and relationships
+
+The SYNC message conveys a time reference with a resolution of 6.94/64 microseconds (9.216 MHz) to allow the CM to track the CMTS clock with a small phase offset. Since this timing reference is decoupled from particular upstream channel characteristics, a single SYNC time reference may be used for all upstream channels associated with the downstream channel.
+
+The bandwidth allocation MAP uses time units of "mini-slots". A mini-slot represents the time needed for transmission of a fixed number of symbols. For some modulations (e.g., QPSK), an integer number of bytes can be transmitted in a mini-slot. For these channels, the mini-slot is expected to represent 16 byte-times, although other values could be chosen.
+
+A "mini-slot" is the unit of granularity for upstream transmission opportunities; there is no implication that any PDU can actually be transmitted in a single mini-slot.
+
+##### J.9.3.4.1.1 Mini-slot capacity
+
+On TDMA channels, the size of the mini-slot, expressed as a multiple of the SYNC time reference, is carried in the upstream channel descriptor. The example in Table J.9-1 relates mini-slots to the SYNC time ticks (assuming QPSK modulation):
+
+**Table J.9-1 – Example relating mini-slots to time ticks**
+
+| Parameter              | Example value                            |
+|------------------------|------------------------------------------|
+| Time tick              | 6.94 microseconds                        |
+| Bytes per mini-slot    | 16 (nominal, when using QPSK modulation) |
+| Symbols/byte           | 4 (assuming QPSK)                        |
+| Symbols/second         | 2 304 000                                |
+| Mini-slots/second      | 36'000                                   |
+| Microseconds/mini-slot | 27.7                                     |
+| Ticks/mini-slot        | 4                                        |
+
+Note that the symbols/byte is a characteristic of an individual burst transmission, not of the channel. A mini-slot in this instance could represent a minimum of 16 or a maximum of 48 bytes, depending on the modulation choice.
+
+In a channel allocated exclusively to DOCS 2.0 TDMA modems, the mini-slot size field of the UCD MAY take on the value 0, in which case the mini-slot size is 1 timebase tick. If a channel is to
+
+be accessible to both DOCS 1.x and 2.0 TDMA cable modems, the UCD MUST follow the DOCS 1.x requirements for timing units and relationships.
+
+#### J.9.3.4.2.1 Mini-slot capacity
+
+On S-CDMA channels, the size of the mini-slot is dependent on the modulation rate, the codes per mini-slot, and the spreading intervals per frame, which are all carried in the upstream channel descriptor. The timing units and relationships for S-CDMA are covered in detail in clause 6.2.11, "S-CDMA framer and interleaver". An example of the timing relationships (assuming 64QAM modulation) is shown in Table J.9-2:
+
+**Table J.9-2 – Example of mini-slot capacity in S-CDMA mode**
+
+| Parameter                     | Example value                             |
+|-------------------------------|-------------------------------------------|
+| Spreading intervals per frame | 10                                        |
+| Active code length            | 128                                       |
+| Codes per mini-slot           | 4                                         |
+| Mini-slots per frame          | 32                                        |
+| Symbols per mini-slot         | 40                                        |
+| Bytes per mini-slot           | 30 (nominal, when using 64QAM modulation) |
+| Bits/symbol                   | 6 (assuming 64QAM)                        |
+| Symbols/second                | 4'608'000                                 |
+| Mini-slots/second             | 115'200                                   |
+| Microseconds/mini-slot        | 8.680 <u>5</u>                            |
+
+#### J.9.5 Data link encryption support
+
+Refer to clause 9.5
+
+#### J.10 Quality of service and fragmentation
+
+Refer to clause 10.
+
+#### J.11 Cable modem – CMTS interaction
+
+##### J.11.2.10 Baseline privacy initialization
+
+Following registration, if the CM is provisioned to run baseline privacy, the CM MUST initialize baseline privacy operations, as described in [DOCS8]. A CM is provisioned to run baseline privacy if the privacy enable TLV (see clause C.1.1.16) in the DOCS 1.1-style configuration file is explicitly/implicitly set to enable or the baseline privacy configuration setting (see clause C.3.2) is contained in the DOCS 1.0-style configuration file as specified in clauses A.1.1 and C.2 of the BPI+ spec [DOCS8]. Note that the secure software download is required regardless of whether the CM is provisioned to run baseline privacy or not, as specified in Appendix D of the BPI+ spec [DOCS8].
+
+In order to ease operations and reduce cost, the manufacturer CA certificate of the CM MAY be self-signed.
+
+#### J.C Common radio frequency interface encodings
+
+##### J.C.2.2.6.11 Unsolicited grant time reference
+
+For unsolicited grant service and unsolicited grant service with activity detection, the value of this parameter specifies a reference time  $t_0$  from which can be derived the desired transmission times
+
+$t_i = t_0 + i \times \text{interval}$ , where interval is the nominal grant interval (refer to clause C.2.2.6.7). This parameter is applicable only for messages transmitted from the CMTS to the CM, and only when a UGS or UGS-AD service flow is being made active. In such cases, this is a mandatory parameter.
+
+| Type  | Length | Value          | Valid range     |
+|-------|--------|----------------|-----------------|
+| 24.24 | 4      | CMTS timestamp | 0-4'294'967'295 |
+
+The timestamp specified in this parameter represents a count state of the CMTS 9.216-MHz master clock. Since a UGS or UGS-AD service flow is always activated before transmission of this parameter to the modem, the reference time  $t_0$  is to be interpreted by the modem as the ideal time of the next grant only if  $t_0$  follows the current time. If  $t_0$  precedes the current time, the modem can calculate the offset from the current time to the ideal time of the next grant according to:
+
+$$\text{interval} - (((\text{current time} - t_0)/9.216) \bmod \text{interval})$$
+
+where interval is in units of microseconds, and current time and  $t_0$  are in 9.216-MHz units.
+
+## J.E The data-over-cable spanning tree protocol
+
+### J.E.4.1 Path cost
+
+In [b-ISO/IEC 10038], the following formula is used:
+
+$$\text{Path\_Cost} = 1000/\text{Attached\_LAN\_speed\_in\_Mb/s}$$
+
+For CMs, this formula is adapted as:
+
+$$\text{Path\_Cost} = 1000/(\text{Upstream\_modulation\_rate} \times \text{bits\_per\_Symbol\_for\_long\_data\_grant})$$
+
+That is, the modulation type (QPSK or 16QAM) for the long data grant IUC is multiplied by the raw modulation rate to determine the nominal path cost. Table J.E-1 provides the derived values.
+
+**Table J.E-1 – CM path cost**
+
+| Modulation rate | Default path cost |       |
+|-----------------|-------------------|-------|
+|                 | QPSK              | 16QAM |
+| kHz             |                   |       |
+| 144             | 3472              | 1736  |
+| 288             | 1736              | 868   |
+| 596             | 868               | 434   |
+| 1152            | 434               | 217   |
+| 2304            | 217               | 108   |
+
+For CMTSs, this formula is:
+
+$$\text{Path\_Cost} = 1000/(\text{Downstream\_symbol\_rate} \times \text{bits\_per\_symbol})$$
+
+# Appendix I
+
+## MAC service definition
+
+(This appendix does not form an integral part of this Recommendation)
+
+This appendix is informative. In case of conflict between this appendix and any normative section of this Recommendation, the normative section takes precedence.
+
+### I.1 MAC service overview
+
+The DOCS MAC provides a protocol service interface to upper-layer services. Examples of upper-layer services include a DOCS bridge, embedded applications (e.g., IPCablecom/VoIP), a host interface (e.g., NIC adapter with NDIS driver), and layer three routers (e.g., IP router).
+
+The MAC service interface defines the functional layering between the upper-layer service and the MAC. As such it defines the functionality of the MAC which is provided by the underlying MAC protocols. This interface is a protocol interface, not a specific implementation interface.
+
+The following data services are provided by the MAC service interface:
+
+- A MAC service exists for classifying and transmitting packets to MAC service flows.
+- A MAC service exists for receiving packets from MAC service flows. Packets may be received with suppressed headers.
+- A MAC service exists for transmitting and receiving packets with suppressed headers. The headers of transmitted packets are suppressed based upon matching classifier rules. The headers of received suppressed packets are regenerated based upon a packet header index negotiated between the CM and CMTS.
+- A MAC service exists for synchronization of grant timing between the MAC and the upper-layer service. This clock synchronization is required for applications such as embedded IPCablecom VoIP clients in which the packetization period needs to be synchronized with the arrival of scheduled grants from the CMTS.
+- A MAC service exists for synchronization of the upper-layer clock with the CMTS controlled master clock.
+
+It should be noted that a firewall and policy based filtering service may be inserted between the MAC layer and the upper-layer service, but such a service is not modelled in this MAC service definition.
+
+The following control services are provided by the MAC service interface:
+
+- A MAC service exists for the upper layer to learn of the existence of provisioned service flows and QoS traffic parameter settings at registration time.
+- A MAC service exists for the upper layer to create service flows. Using this service, the upper layer initiates the admitted/activated QoS parameter sets, classifier rules and packet suppression headers for the service flow.
+- A MAC service exists for the upper layer to delete service flows.
+- A MAC service exists for the upper layer to change service flows. Using this service, the upper layer modifies the admitted/activated QoS parameter sets, classifier rules and packet suppression headers.
+- A MAC service exists for controlling the classification of and transmission of PDUs with suppressed headers. At most, a single suppressed header is defined for a single classification rule. The upper-layer service is responsible for defining both the definition of suppressed headers (including wild-card do-not-suppress fields) and the unique
+
+classification rule that discriminates each header. In addition to the classification rule, the MAC service can perform a full match of all remaining header bytes to prevent generation of false headers if so configured by the upper-layer service.
+
+- A MAC service exists for controlling two-phase control of QoS traffic resources. Two-phase activation is controlled by the upper-layer service to provide both admitted QoS parameters and active QoS parameters within the appropriate service request. Upon receipt of an affirmative indication, the upper-layer service knows that the admitted QoS parameter set has been reserved by the CMTS, and that the activated QoS parameter set has been activated by the CMTS. Barring catastrophic failure (such as resizing of the bandwidth of the upstream PHY), admitted resources will be guaranteed to be available for activation, and active resources will be guaranteed to be available for use in packet transmission.
+
+A control function for locating an unused service flow and binding it, or a specific identified service flow, to a specific upper-layer service may also exist. The details of such a function are not specified and are implementation-dependent.
+
+Other control functions may exist at the MAC service interface, such as functions for querying the status of active service flows and packet classification tables, or functions from the MAC service to the upper-layer service to enable the upper-layer service to authorize service flows requested by the peer MAC layer service, but those functions are not modelled in this MAC service definition.
+
+Other MAC services that are not service flow-related also exist, such as functions for controlling the MAC service MAC address and SAID multicast filtering functions, but those functions are not modelled in this MAC service definition.
+
+### **I.1.1 MAC service parameters**
+
+The MAC service utilizes the following parameters. For a full description of the parameters, consult the theory of operation and other relevant clauses within the body of the RFI Recommendation.
+
+- Service flow QoS traffic parameters
+
+MAC activate-service-flow and change-service-flow primitives allow common, upstream and downstream QoS traffic parameters to be provided. When such parameters are provided, they override whatever values were configured for those parameters at provisioning time or at the time the service flow was created by the upper-layer service.
+
+- Active/admitted QoS traffic parameters
+
+If two-phase service flow activation is being used, then two complete sets of QoS traffic parameters are controlled. The admitted QoS parameters state the requirements for reservation of resources to be authorized by the CMTS. The activated QoS parameters state the requirements for activation of resources to be authorized by the CMTS. Admitted QoS parameters may be activated at a future time by the upper-layer service. Activated QoS parameters may be used immediately by the upper-layer service.
+
+- Service flow classification filter rules
+
+Zero or more classification filter rules may be provided for each service flow that is controlled by the upper-layer service. Classifiers are identified with a classifier identifier.
+
+- Service flow PHS suppressed headers
+
+Zero or more PHS suppressed header strings with their associated verification control and mask variables may be defined for each service flow. When such headers are defined, they are associated 1-to-1 with specific classification rules. In order to regenerate packets with suppressed headers, a payload header suppression index is negotiated between the CM and CMTS.
+
+## I.2 MAC data service interface
+
+MAC services are defined for transmission and reception of data to and from service flows. Typically, an upper-layer service will utilize service flows for mapping of various classes of traffic to different service flows. Mappings to service flows may be defined for low priority traffic, high priority traffic and multiple special traffic classes such as constant bit-rate traffic that is scheduled by periodic grants from the CMTS at the MAC layer.
+
+The following specific data service interfaces are provided by the MAC service to the upper-layer service. These represent an abstraction of the service provided and do not imply a particular implementation:
+
+- MAC\_DATA.request;
+- MAC\_DATA.indicate;
+- MAC\_GRANT\_SYNCHRONIZE.indicate;
+- MAC\_CMTS\_MASTER\_CLOCK\_SYNCHRONIZE.indicate;
+- MAC\_DATA.request.
+
+Issued by the upper-layer service to request classification and transmission of an IEEE 802.3 or DIX-formatted PDU to the RF.
+
+### Parameters
+
+- PDU – IEEE 802.3 or DIX-encoded PDU including all layer-2 header fields and optional FCS. PDU is the only mandatory parameter.
+- Padding – Used when the PDU is less than 60 bytes and it is desired to maintain ISO/IEC 8802-3 transparency.
+- ServiceFlowID – If included, the MAC service circumvents the packet classification function and maps the packet to the specific service flow indicated by the ServiceFlowID value.
+- ServiceClassName, RulePriority – If included, this tuple identifies the service class name of an active service flow to which the packet is to be mapped so long as a classifier does not exist at a rule priority higher than the rule priority supplied.
+
+### Expanded service description
+
+Transmit a PDU from upper-layer service to MAC/PHY. The only mandatory parameter is PDU. PDU contains all layer-2 headers, layer-3 headers, data and (optional) layer-2 checksum.
+
+If PDU is the only parameter, the packet is subjected to the MAC packet classification filtering function in order to determine how the packet is mapped to a specific service flow. The results of the packet classification operation determine on which service flow the packet is to be transmitted and whether or not the packet should be transmitted with suppressed headers.
+
+If the parameter ServiceFlowID is supplied, the packet can be directed to the specifically-identified service flow.
+
+If the parameter tuple ServiceClassName, RulePriority is supplied, the packet is directed to the first active service flow that matches the service class name so long as a classifier does not exist at a rule priority higher than the rule priority supplied. This service is used by upper-layer policy enforcers to allow zero or more dynamic rules to be matched for selected traffic (e.g., voice) while all other traffic is forced to a service flow within the named service flow class. If no active service flow with the service class name exists, then the service performs normal packet classification.
+
+In all cases, if no classifier match is found, or if none of the combinations of parameters maps to a specific service flow, the packet will be directed to the primary service flow.
+
+The following pseudo-code describes the intended operation of the MAC\_DATA.request service interface.
+
+### I.2.1 MAC\_DATA.request
+
+```
+PDU
+[ServiceFlowID]
+[ServiceClassName, RulePriority]
+```
+
+FIND\_FIRST\_SERVICE\_FLOW\_ID (ServiceClassName) returns ServiceFlowID of first service flow whose ServiceClassName equals the parameter of the procedure or NULL if no matching service flow is found.
+
+SEARCH\_CLASSIFIER\_TABLE (PriorityRange) searches all rules within the specified priority range and returns either the ServiceFlowID associated with the rule or NULL if no classifier rule is found.
+
+```
+TxServiceFlowID = NULL
+IF (ServiceFlowID DEFINED)
+    TxServiceFlowID = MAC_DATA.ServiceFlowID
+ELSEIF (ServiceClassName DEFINED and RulePriority DEFINED)
+    TxServiceFlowID = FIND_FIRST_SERVICE_FLOW_ID (ServiceClassName)
+    SearchID = SEARCH_CLASSIFIER_TABLE (All Priority Levels)
+    IF (SearchID not NULL and ClassifierRule.Priority >=
+MAC_DATA.RulePriority)
+        TxServiceFlowID = SearchID
+ELSE [PDU only]
+    TxServiceFlowID = SEARCH_CLASSIFIER_TABLE (All Priority Levels)
+IF (TxServiceFlowID = NULL)
+    TRANSMIT_PDU (PrimaryServiceFlowID)
+ELSE
+    TRANSMIT_PDU (TxServiceFlowID)
+```
+
+### I.2.2 MAC\_DATA.indicate
+
+Issued by the MAC to indicate reception of an IEEE 802.3 or DIX PDU for the upper-layer service from the RF.
+
+#### Parameters
+
+- PDU – IEEE 802.3 or DIX-encoded PDU including all layer-2 header fields and FCS.
+
+### I.2.3 MAC\_GRANT\_SYNCHRONIZE.indicate
+
+Issued by the MAC service to the upper-layer service to indicate the timing of grant arrivals from the CTMS. It is not stated how the upper layer derives the latency, if any, between the reception of the indication and the actual arrival of grants (within the bounds of permitted grant jitter) from the CMTS. It should be noted that in UGS applications it is expected that the MAC layer service will increase the grant rate or decrease the grant rate based upon the number of grants per interval QoS traffic parameter. It should also be noted that as the number of grants per interval is increased or decreased, the timing of grant arrivals will change also. It should also be noted that when synchronization is achieved with the CMTS downstream master clock, this indication may only be required once per active service flow. No implication is given as to how this function is implemented.
+
+#### Parameters
+
+- ServiceFlowID – Unique identifier value for the specific active service flow receiving grants.
+
+#### **I.2.4 MAC\_CMTS\_MASTER\_CLOCK\_SYNCHRONIZE.indicate**
+
+Issued by the MAC service to the upper-layer service to indicate the timing of the CMTS master clock. No implication is given as to how often or how many times this indication is delivered by the MAC service to the upper-layer service. No implication is given as to how this function is implemented.
+
+##### **Parameters**
+
+- No parameters specified.
+
+#### **I.3 MAC control service interface**
+
+A collection of MAC services are defined for control of MAC service flows and classifiers. It should be noted that an upper-layer service may use these services to provide an upper-layer traffic construct such as "connections" or "subflows" or "micro-flows". However, except for the ability to modify individual classifiers, no explicit semantics is defined for such upper layer models. Thus, control of MAC service flow QoS parameters is specified in the aggregate.
+
+The following specific control service interface functions are provided by the MAC service to the upper-layer service. These represent an abstraction of the service provided and do not imply a particular implementation:
+
+- MAC\_REGISTRATION\_RESPONSE.indicate;
+- MAC\_CREATE\_SERVICE\_FLOW.request/response/indicate;
+- MAC\_DELETE\_SERVICE\_FLOW.request/response/indicate;
+- MAC\_CHANGE\_SERVICE\_FLOW.request/response/indicate.
+
+##### **I.3.1 MAC\_REGISTRATION\_RESPONSE.indicate**
+
+Issued by the DOSCIS MAC to the upper-layer service to indicate the complete set of service flows and service flow QoS traffic parameters that have been provisioned and authorized by the registration phase of the MAC. Subsequent changes to service flow activation state or addition and deletion of service flows are communicated to the upper-layer service with indications from the other MAC control services.
+
+##### **Parameters**
+
+- Registration TLVs – Any and all TLVs that are needed for service flow and service flow parameter definition including provisioned QoS parameters. See the normative body of this Recommendation for more details.
+
+##### **I.3.2 MAC\_CREATE\_SERVICE\_FLOW.request**
+
+Issued by the upper-layer service to the MAC to request the creation of a new service flow within the MAC service. This primitive is not issued for service flows that are configured and registered, but rather for dynamically-created service flows. This primitive may also define classifiers for the service flow and supply admitted and activated QoS parameters. This function invokes DSA signalling.
+
+##### **Parameters**
+
+- ServiceFlowID – Unique ID value for the specific service flow being created.
+- ServiceClassName – service flow class name for the service flow being created.
+- Admitted QoS parameters – Zero or more upstream, downstream and common traffic parameters for the service flow.
+- Activated QoS parameters – Zero or more upstream, downstream and common traffic parameters for the service flow.
+
+- Service flow payload header suppression rules – Zero or more PHS rules for each service flow that is controlled by the upper-layer service.
+- Service flow classification filter rules – Zero or more classification filter rules for each service flow that is controlled by the upper-layer service. Classifiers are identified with a classifier identifier.
+
+### **I.3.3 MAC\_CREATE\_SERVICE\_FLOW.response**
+
+Issued by the MAC service to the upper-layer service to indicate the success or failure of the request to create a service flow.
+
+#### **Parameters**
+
+- ServiceFlowID – Unique identifier value for the specific service flow being created.
+- ResponseCode – Success or failure code.
+
+### **I.3.4 MAC\_CREATE\_SERVICE\_FLOW.indicate**
+
+Issued by the MAC service to notify the upper-layer service of the creation of a new service flow within the MAC service. This primitive is not issued for service flows that have been administratively pre-configured, but rather for dynamically defined service flows. In this Recommendation, this notification is advisory only.
+
+#### **Parameters**
+
+- ServiceFlowID – Unique ID value for the specific service flow being created.
+- ServiceClassName – service flow class name for the service flow being created.
+- Admitted QoS parameters – Zero or more upstream, downstream and common traffic parameters for the service flow.
+- Activated QoS parameters – Zero or more upstream, downstream and common traffic parameters for the service flow.
+- Service flow payload header suppression rules – Zero or more PHS rules for each service flow that is controlled by the upper-layer service.
+- Service flow classification filter rules – Zero or more classification filter rules for each service flow that is controlled by the upper-layer service. Classifiers are identified with a classifier identifier.
+
+### **I.3.5 MAC\_DELETE\_SERVICE\_FLOW.request**
+
+Issued by the upper-layer service to the MAC to request the deletion of a service flow and all QoS parameters including all associated classifiers and PHS rules. This function invokes DSD signalling.
+
+#### **Parameters**
+
+- ServiceFlowID(s) – Unique identifier value(s) for the deleted service flow(s).
+
+### **I.3.6 MAC\_DELETE\_SERVICE\_FLOW.response**
+
+Issued by the MAC service to the upper-layer service to indicate the success or failure of the request to delete a service flow.
+
+#### **Parameters**
+
+- ResponseCode – Success or failure code.
+
+### **I.3.7 MAC\_DELETE\_SERVICE\_FLOW.indicate**
+
+Issued by the MAC service to notify the upper-layer service of deletion of a service flow within the MAC service.
+
+### Parameters
+
+- ServiceFlowID(s) – Unique identifier value(s) for the deleted service flow(s).
+
+### I.3.8 MAC\_CHANGE\_SERVICE\_FLOW.request
+
+Issued by the upper-layer service to the MAC to request modifications to a specific created and acquired service flow. This function is able to define both the complete set of classifiers and incremental changes to classifiers (add/remove). This function defines the complete set of admitted and active QoS parameters for a service flow. This function invokes DSC MAC-layer signalling.
+
+### Parameters
+
+- ServiceFlowID – Unique identifier value for the specific service flow being modified.
+- Zero or more packet classification rules with add/remove semantics and LLC, IP and 802.1PQ parameters.
+- Admitted QoS parameters – Zero or more upstream, downstream and common traffic parameters for the service flow.
+- Activated QoS parameters – Zero or more upstream, downstream and common traffic parameters for the service flow.
+- Service flow payload header suppression rules – Zero or more PHS rules for each service flow that is controlled by the upper-layer service.
+
+### I.3.9 MAC\_CHANGE\_SERVICE\_FLOW.response
+
+Issued by the MAC service to the upper-layer service to indicate the success or failure of the request to change a service flow.
+
+### Parameters
+
+- ServiceFlowID – Unique identifier value for the specific service flow being released.
+- ResponseCode – Success or failure code.
+
+### I.3.10 MAC\_CHANGE\_SERVICE\_FLOW.indicate
+
+Issued by the DOSCIS MAC service to notify upper-layer service of a request to change a service flow. In this Recommendation, the notification is advisory only and no confirmation is required before the service flow is changed. Change-service-flow indications are generated based upon DSC signalling. DSC signalling can be originated based upon change-service-flow events between the peer upper-layer service and its MAC service, or based upon network resource failures such as a resizing of the total available bandwidth at the PHY layer. How the upper-layer service reacts to forced reductions in admitted or reserved QoS traffic parameters is not specified.
+
+### Parameters
+
+- ServiceFlowID – Unique identifier for the service flow being activated.
+- Packet classification rules with LLC, IP and 802.1PQ parameters, and with zero or more PHS\_CLASSIFIER\_IDENTIFIERS.
+- Admitted QoS parameters – Zero or more upstream, downstream and common traffic parameters for the service flow.
+- Activated QoS parameters – Zero or more upstream, downstream and common traffic parameters for the service flow.
+- Service flow payload header suppression rules – Zero or more PHS rules for each service flow that is controlled by the upper-layer service.
+
+## I.4 MAC service usage scenarios
+
+Upper-layer entities utilize the services provided by the MAC in order to control service flows and in order to send and receive data packets. The partition of function between the upper-layer service and the MAC service is demonstrated by the following scenarios.
+
+### I.4.1 Transmission of PDUs from upper-layer service to MAC DATA service
+
+- Upper-layer service transmits PDUs via the MAC\_DATA service.
+- MAC\_DATA service classifies transmitted PDUs using the classification table, and transmits the PDUs on the appropriate service flow. The classification function may also cause the packet header to be suppressed according to a header suppression template stored with the classification rule. It is possible for the upper-layer service to circumvent this classification function.
+- MAC\_DATA service enforces all service flow-based QoS traffic shaping parameters.
+- MAC\_DATA service transmits PDUs on DOCS RF as scheduled by the MAC layer.
+
+### I.4.2 Reception of PDUs to upper-layer service from MAC DATA service
+
+PDUs are received from the DOCS RF.
+
+If a PDU is sent with a suppressed header, the header is regenerated before the packet is subjected to further processing.
+
+In the CMTS, the MAC\_DATA service classifies the PDU's ingress from the RF using the classification table and then polices the QoS traffic shaping and validates addressing as performed by the CM. In the CM, no per-packet service flow classification is required for traffic ingress from the RF.
+
+Upper-layer service receives PDUs from the MAC\_DATA.indicate service.
+
+### I.4.3 Sample sequence of MAC control and MAC data services
+
+A possible CM-oriented sequence of MAC service functions for creating, acquiring, modifying and then using a specific service flow is as follows:
+
+- MAC\_REGISTER\_RESPONSE.indicate  
+Learn of any provisioned service flows and their provisioned QoS traffic parameters.
+- MAC\_CREATE\_SERVICE\_FLOW.request/response  
+Create new service flow. This service interface is utilized if the service flow was learned as not provisioned by the MAC\_REGISTER\_RESPONSE service interface. Creation of a service flow invokes DSA signalling.
+- MAC\_CHANGE\_SERVICE\_FLOW.request/response  
+Define admitted and activated QoS parameter sets, classifiers and packet suppression headers. Change of a service flow invokes DSC signalling.
+- MAC\_DATA.request  
+Send PDUs to MAC service for classification and transmission.
+- MAC\_DATA.indication  
+Receive PDUs from MAC service.
+- MAC\_DELETE\_SERVICE\_FLOW.request/response  
+Delete service flow. Would likely be invoked only for dynamically-created service flows, not provisioned service flows. Deletion of a service flow uses DSD signalling.
+
+## Appendix II
+
+### Example preamble sequence
+
+(This appendix does not form an integral part of this Recommendation)
+
+#### II.1 Introduction
+
+A programmable preamble superstring, up to 1536 bits long, is part of the channel-wide profile or attributes, common to the all-burst profiles on the channel (see Table 8-18), but with each burst profile able to specify the start location within this sequence of bits and the length of the preamble (see Table 8-19). The first bit of the preamble pattern is designated by the preamble value offset as described in Table 8-19. The first bit of the preamble pattern is the first bit into the symbol mapper (Figure 6-2, "TDMA upstream transmission processing" and Figure 6-3, "S-CDMA upstream transmission processing"), and is the first symbol of the burst (see clause 6.2.13, "symbol mapping"). As an example, per Table 8-19, for preamble offset value = 100, the 101st bit of the preamble superstring is the first bit into the symbol mapper, and the 102nd bit is the second bit into the mapper, and is mapped to Q1, and so. An example 1536-bit-long preamble superstring is given in clause II.2.
+
+#### II.2 Example preamble sequence
+
+The following is the example 1536-bit preamble sequence:
+
+##### Bits 1 through 128:
+
+1100 0011 1111 0000 0011 0011 1111 1100 0011 0011 0000 0011 1100 0000 0011 0000  
+0000 1110 1101 0001 0001 1110 1110 0101 0010 0101 0010 0101 1110 1110 0010 1110
+
+##### Bits 129 through 256:
+
+0010 1110 1110 0010 0010 1110 1110 1110 1110 1110 0010 0010 0010 1110 1110 0010  
+1110 1110 1110 0010 1110 0010 1110 0010 0010 0010 0010 1110 0010 0010 1110 0010
+
+##### Bits 257 through 384:
+
+0010 1010 0110 0110 0110 1110 1110 1110 0010 1110 0010 1110 0010 1110 0110 1010  
+0010 1110 1110 1010 0110 1110 0110 0010 0110 1110 1010 1110 0010 1010 0110 0010
+
+##### Bits 385 through 512:
+
+0010 1110 0110 1110 0010 1010 1010 0110 0010 1110 0110 0110 1110 0010 0010 0110  
+0010 1110 0010 1010 0010 1110 0110 0010 0010 1010 0010 0110 0010 1010 0010 1010
+
+##### Bits 513 through 640:
+
+0010 1110 0110 1110 0110 0110 1110 0010 0110 1010 0110 0010 1110 1110 1010 0010  
+1110 1110 0010 1110 1110 1110 0010 1110 1110 0010 1110 0010 0010 1110 0010 0010
+
+##### Bits 641 through 768:
+
+1110 1110 1110 0010 0010 0010 1110 0010 1110 1110 1110 1110 0010 0010 1110 0010  
+1110 0010 0010 0010 1110 1110 0010 0010 0010 0010 1110 0010 0010 0010 0010 1110
+
+##### Bits 769 through 896:
+
+0011 0000 1111 1100 0000 1100 1111 1111 0000 1100 1100 0000 1111 0000 0000 1100  
+0000 0000 1111 1111 1111 0011 0011 0011 1100 0011 1100 1111 1100 1111 0011 0000
+
+##### Bits 897 through 1024:
+
+1100 0011 1111 0000 0011 0011 1111 1100 0011 0011 0000 0011 1100 0000 0011 0000  
+0000 1110 1101 0001 0001 1110 1110 0101 0010 0101 0010 0101 1110 1110 0010 1110
+
+##### Bits 1025 through 1152:
+
+0010 1110 1110 0010 0010 1110 1110 1110 1110 1110 0010 0010 0010 1110 1110 0010  
+1110 1110 1110 0010 1110 0010 1110 0010 0010 0010 0010 1110 0010 0010 1110 0010
+
+##### Bits 1153 through 1280:
+
+0010 0010 1110 1110 1110 1110 1110 1110 0010 1110 0010 1110 0010 1110 1110 0010  
+0010 1110 1110 0010 1110 1110 1110 0010 1110 1110 0010 1110 0010 0010 1110 0010
+
+**Bits 1281 through 1408:**
+
+1100 1100 1111 0000 1111 1111 1100 0000 1111 0011 1111 0011 0011 0000 0000 1100  
+0011 0000 0011 1111 1111 1100 1100 1100 1111 0000 1111 0011 1111 0011 1100 1100
+
+**Bits 1409 through 1536:**
+
+0011 0000 1111 1100 0000 1100 1111 1111 0000 1100 1100 0000 1111 0000 0000 1100  
+0000 0000 1111 1111 1111 0011 0011 0011 1100 0011 1100 1111 1100 1111 0011 0000
+
+## Appendix III
+
+### Multiple upstream channels
+
+(This appendix does not form an integral part of this Recommendation)
+
+This appendix is informative. In case of conflict between this appendix and any normative part of this Recommendation, the normative part takes precedence.
+
+Clause 7.2, "MPEG packet format", describes support for multiple upstream and multiple downstream channels within a DOCS domain. The permutations that a CM may see on the cable segment it is attached to include:
+
+- single downstream and single upstream per cable segment;
+- single downstream and multiple upstreams per cable segment;
+- multiple downstreams and single upstream per cable segment;
+- multiple downstreams and multiple upstreams per cable segment.
+
+A typical application that will require one upstream and one downstream per CM is web browsing. Web browsing tends to have asymmetrical bandwidth requirements that match closely to the asymmetrical bandwidth of DOCS.
+
+A typical application that will require access to one of multiple upstreams per CM is IP telephony. IP telephony tends to have symmetrical bandwidth requirements. If there is a large concentration of CMs in a geographical area all served by the same fibre node, more than one upstream may be required in order to provide sufficient bandwidth and prevent call blocking.
+
+A typical application that will require access to one of multiple downstreams per CM is IP streaming video. IP streaming video tends to have extremely large downstream bandwidth requirements. If there is a large concentration of CMs in a geographical area, all served by the same fibre node, more than one downstream may be required in order to provide sufficient bandwidth and to deliver multiple IP video streams to multiple CMs.
+
+A typical application that will require multiple downstreams and multiple upstreams is when the above applications are combined, and it is more economical to have multiple channels than it is to physically subdivide the HFC network.
+
+The role of the CM in these scenarios would be to be able to move between multiple upstreams and between multiple downstreams. The role of the CMTS would be to manage the traffic load to all attached CMs, and balance the traffic between the multiple upstreams and downstreams by dynamically moving the CMs based upon their resource needs and the resources available.
+
+This appendix looks at the implementation considerations for these cases. Specifically, the first and last application are profiled. These examples are meant to illustrate one topology and one implementation of that topology.
+
+#### III.1 Single downstream and single upstream per cable segment
+
+This clause presents an example of a single downstream channel and four upstream channels. In Figure III.1, the four upstream channels are on separate fibres serving four geographical communities of modems. The CMTS has access to the one downstream and all four upstreams, while each CM has access to the one downstream and only one upstream.
+
+![Diagram of a single downstream and single upstream channels per CM topology. On the left, a CMTS is connected to a 'Downstream laser and upstream receiver'. The downstream path (f_D0) is a shared fibre that branches to four 'Fibre nodes'. Each fibre node has a downstream laser and an upstream receiver. The upstream paths (f_U0, f_U1, f_U2, f_U3) are individual fibres from each fibre node's upstream receiver back to the CMTS. Each fibre node is connected to a 'CM' (Cable Modem) via a coaxial cable. The diagram is labeled with 'Coax', 'Fibre', and 'Coax' at the bottom, and 'J.122_FIII-1' in the bottom right corner.](1130851355a5fcae4ddb250196fe9092_img.jpg)
+
+Diagram of a single downstream and single upstream channels per CM topology. On the left, a CMTS is connected to a 'Downstream laser and upstream receiver'. The downstream path (f\_D0) is a shared fibre that branches to four 'Fibre nodes'. Each fibre node has a downstream laser and an upstream receiver. The upstream paths (f\_U0, f\_U1, f\_U2, f\_U3) are individual fibres from each fibre node's upstream receiver back to the CMTS. Each fibre node is connected to a 'CM' (Cable Modem) via a coaxial cable. The diagram is labeled with 'Coax', 'Fibre', and 'Coax' at the bottom, and 'J.122\_FIII-1' in the bottom right corner.
+
+**Figure III.1 – Single downstream and single upstream channels per CM**
+
+In this topology, the CMTS transmits upstream channel descriptors (UCDs) and MAPs for each of the four upstream channels related to the shared downstream channel.
+
+Unfortunately, each CM cannot determine which fibre branch it is attached to because there is no way to convey the geographical information on the shared downstream channel. At initialization, the CM randomly picks a UCD and its corresponding MAP. The CM then chooses an initial maintenance opportunity on that channel and transmits a ranging request.
+
+The CMTS will receive the ranging request and will redirect the CM to the appropriate upstream channel identifier by specifying the upstream channel ID in the ranging response. The CM MUST then use the channel ID of the ranging response, not the channel ID on which the ranging request was initiated. This is necessary only on the first ranging response received by the CM. The CM SHOULD continue the ranging process normally and proceed to wait for station maintenance IEs.
+
+From then on, the CM will be using the MAP that is appropriate to the fibre branch to which it is connected. If the CM ever has to redo initial ranging, it may start with its previous known UCD instead of choosing one at random.
+
+A number of constraints are imposed by this topology:
+
+- All initial maintenance opportunities across all fibre nodes must be aligned. If there are multiple logical upstreams sharing the same spectrum on a fibre, then the initial maintenance opportunities for each of the logical upstreams MUST align with the initial maintenance opportunity of at least one logical upstream with the same centre frequency on each fibre node. When the CM chooses a UCD to use and then subsequently uses the MAP for that channel, the CMTS must be prepared to receive a ranging request at that initial maintenance opportunity. Note that only the initialization intervals must be aligned. Once the CM is successfully ranged on an upstream channel, its activities need only be aligned
+
+with other users on the same upstream channel. In Figure III.1, ordinary data transmission and requests for bandwidth may occur independently across the four upstream channels.
+
+- All of the upstream channels on different nodes should operate at the same frequency or frequencies unless it is known that no other upstream service will be impacted due to a CM transmission of a ranging request on a "wrong" frequency during an initial maintenance opportunity. If the CM chooses an upstream channel descriptor arbitrarily, it could transmit on the wrong frequency if the selected UCD applied to an upstream channel on a different fibre node. This could cause initial ranging to take longer. However, this might be an acceptable system trade-off in order to keep spectrum management independent between cable segments.
+- All of the upstream channels may operate at different modulation rates. However, there is a trade-off involved between the time it takes to acquire ranging parameters and flexibility of upstream channel modulation rate. If upstream modulation rates are not the same, the CMTS would be unable to demodulate the ranging request if it was transmitted at the wrong modulation rate for the particular upstream receiver of the channel. The result would be that the CM would retry as specified in the RFI Recommendation and then would eventually try other upstream channels associated with the currently used downstream. Increasing the probability of attempting ranging on multiple channels increases CM initialization time but using different modulation rates on different fibre nodes allows flexibility in setting the degree of burst noise mitigation.
+- All initial maintenance opportunities on different channels may use different burst characteristics so that the CMTS can demodulate the ranging request. Again, this is a trade-off between time to acquire ranging and exercising flexibility in setting physical-layer parameters among different upstream channels. If upstream burst parameters for initial maintenance are not the same, the CMTS would be unable to demodulate the ranging request if it was transmitted with the wrong burst parameters for the particular channel. The result would be that the CM would retry the ranging request as specified in the RFI Recommendation and then would eventually try other upstream channels associated with the currently used downstream. Increasing the probability of attempting ranging on multiple channels increases CM initialization time but using different burst parameters for initial maintenance on different fibre nodes allows the ability to set parameters appropriate for plant conditions on a specific node.
+
+## III.2 Multiple downstreams and multiple upstreams per cable segment
+
+This clause presents a more complex set of examples of CMs that are served by several downstream channels and several upstream channels and where those upstream and downstream channels are part of one MAC domain. The interaction of initial ranging, normal operation and dynamic channel change are profiled, as well as the impact of the multiple downstreams using synchronized or unsynchronized timestamps.
+
+Synchronized timestamps refer to both downstream paths transmitting a time stamp that is derived from a common clock frequency and have common time bases. The timestamps on each downstream do not have to be transmitted at the same time in order to be considered synchronized.
+
+### III.2.1 Topologies
+
+Suppose two downstream channels are used in conjunction with four upstream channels as shown in Figure III.2. In all three topologies, there are two geographical communities of modems, both served by the same two downstream channels. The difference in the topologies is found in their upstream connectivity.
+
+![Three diagrams showing different network topologies (Topology #1, #2, and #3) for multiple downstream and upstream channels per CM. Each diagram shows a CMTS on the left, fibre nodes in the middle, and CMs on the right, connected by coax and fibre cables. Topology #1 shows dedicated upstream paths. Topology #2 shows a shared upstream path. Topology #3 shows a different shared upstream path configuration.](7215f3487199c803ab7df25c889fbbaf_img.jpg)
+
+The diagram illustrates three network topologies (Topology #1, #2, and #3) for multiple downstream and multiple upstream channels per CM. The components are arranged horizontally: CMTS (Coax), Downstream laser and upstream receiver (Fibre), Fibre nodes (Fibre), and CM (Coax).
+
+- Topology #1:** The CMTS has six ports. Downstream channels  $f_{D0}$  and  $f_{D1}$  are connected to the first two downstream lasers. Upstream channels  $f_{U0}$ ,  $f_{U1}$ ,  $f_{U2}$ , and  $f_{U3}$  are connected to the first four upstream receivers. Each fibre node contains two upstream receivers and two downstream lasers. One fibre node is connected to  $f_{D0}$  and  $f_{U0}$ , and the other to  $f_{D1}$  and  $f_{U1}$ . Each fibre node is connected to a CM.
+- Topology #2:** Similar to Topology #1, but the upstream channels  $f_{U0}$  and  $f_{U1}$  are combined into a single upstream receiver in the CMTS. The fibre nodes remain the same.
+- Topology #3:** Similar to Topology #1, but the upstream channels  $f_{U2}$  and  $f_{U3}$  are combined into a single upstream receiver in the CMTS. The fibre nodes remain the same.
+
+Labels at the bottom indicate the cable types: Coax, Fibre, and Coax. A reference code J.122\_FIII-2 is present in the bottom right.
+
+Three diagrams showing different network topologies (Topology #1, #2, and #3) for multiple downstream and upstream channels per CM. Each diagram shows a CMTS on the left, fibre nodes in the middle, and CMs on the right, connected by coax and fibre cables. Topology #1 shows dedicated upstream paths. Topology #2 shows a shared upstream path. Topology #3 shows a different shared upstream path configuration.
+
+**Figure III.2 – Multiple downstream and multiple upstream channels per CM**
+
+Topology No. 1 has the return path from each fibre node connected to a dedicated set of upstream receivers. A CM will see both downstream channels, but only one upstream channel that is associated with one of the two downstream channels.
+
+Topology No. 2 has the return path from each fibre node combined and then split across all upstream receivers. A CM will see both downstream channels and all four upstream channels in use with both downstream channels.
+
+Topology No. 3 has the return path from each fibre node split and then sent to multiple upstream receivers, each associated with a different downstream channel. A CM will see both downstream channels, and one upstream channel associated with each of the two downstream channels.
+
+Topology No. 1 is the typical topology in use. Movement between downstreams can only occur if the timestamps on both downstreams are synchronized. Topology No. 2 and Topology No. 3 are to compensate for downstreams that have unsynchronized timestamps, and allow movement between downstream channels as long as the upstream channels are changed at the same time.
+
+The CMs are capable of single frequency receive and single frequency transmit.
+
+### III.2.2 Normal operation
+
+Table III.1 lists MAC messages that contain channel IDs.
+
+**Table III.1 – MAC messages with channel IDs**
+
+| MAC message | Downstream channel ID | Upstream channel ID |
+|-------------|-----------------------|---------------------|
+| UCD         | Yes                   | Yes                 |
+| MAP         | No                    | Yes                 |
+| RNG-REQ     | Yes                   | No                  |
+| RNG-RSP     | No                    | Yes                 |
+| DCC-REQ     | Yes                   | Yes                 |
+
+With unsynchronized timestamps:
+
+- Since upstream synchronization relies on downstream timestamps, each upstream channel must be associated with the time stamp of one of the downstream channels.
+- The downstream channels should only transmit MAP messages and UCD messages that pertain to their associated upstream channels.
+
+With synchronized timestamps:
+
+- Since upstream synchronization can be obtained from either downstream channel, all upstreams can be associated with any downstream channel.
+- All MAPs and UCDs for all upstream channels should be sent on all downstream channels. The UCD messages contains a downstream channel ID so that the CMTS can determine with the RNG-REQ message which downstream channel the CM is on. Thus the UCD messages on each downstream will contain different downstream channel IDs even though they might contain the same upstream channel ID.
+
+### III.2.3 Initial ranging
+
+When a CM performs initial ranging, the topology is unknown and the timestamp consistency between downstreams is unknown. Therefore, the CM chooses either downstream channel and any one of the UCDs sent on that downstream channel.
+
+In both cases:
+
+- The upstream channel frequencies within a physical upstream or combined physical upstreams must be different.
+- The constraints specified in clause III.1 apply.
+
+### **III.2.4 Dynamic channel change**
+
+With unsynchronized timestamps:
+
+- When a DCC-REQ is given, it must contain new upstream and new downstream frequency pairs that are both associated with the same timestamp.
+- When the CM resynchronizes to the new downstream, it must allow for timestamp resynchronization without re-ranging unless instructed to do so with the DCC-REQ command.
+- Topology No. 1 will support channel changes between local upstream channels present within a cable segment, but will not support changes between downstream channels. Topology No. 2 and No. 3 will support upstream and downstream channel changes on all channels within the fibre node as long as the new upstream and downstream channel pair are associated with the same timestamp.
+
+With synchronized timestamps:
+
+- Downstream channel changes and upstream channel changes are independent of each other.
+
+Topologies No. 1, No. 2, and No. 3 will support changes between all upstream and all downstream channels present within the cable segment.
+
+## Appendix IV
+
+### DOCS transmission and contention resolution
+
+(This appendix does not form an integral part of this Recommendation)
+
+#### IV.1 Introduction
+
+This appendix clarifies how the DOCS transmission and contention-resolution algorithms work. It contains a few minor simplifications and assumptions, but should be useful to help clarify this area of the Recommendation.
+
+The simplifications include:
+
+- The text does not explicitly discuss packet arrivals while deferring or waiting for pending grants, nor the sizing of piggyback requests.
+- The CM always sends a piggyback request for the next frame in the last fragment and not inside one of the headers of the original frame.
+- Much of this applies to concatenation, but no attempt is made to address all the subtleties of that situation.
+
+The assumptions include, among others:
+
+- The assumption is made that a request always fits in any request/data region.
+- When a piggyback request is sent with a contention data packet, the state machine only checks for the grant to the request and assumes the data ack for the contention data packet was supplied by the CMTS.
+
+![Transmission and deference state transition diagram showing four states: Idle, Deferring, Data ack pending, and Grant pending. Transitions are triggered by various conditions like queue status, retries, or specific data types (reserved, fragmented, or requested).](cf6b2e5b134aeadae43f0ba8d04dea2f_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> Idle
+    Idle --> Idle : !Queue_Empty
+    Idle --> Deferring : Tx resv. data w/o piggyback
+    Idle --> Data ack pending : Data ack'ed OR too many retries OR map lost
+    Idle --> Grant pending : Tx resv. data w/o piggyback OR too many retries OR (TX frag w/o piggyback && Last)
+    Deferring --> Idle : Map: defer
+    Deferring --> Data ack pending : Tx cont. data w/o piggyback
+    Deferring --> Grant pending : TX Frag w/piggyback OR (TX frag w/o piggyback && !Last) OR Tx request OR Tx resv./cont. data W/piggyback OR grant pending
+    Data ack pending --> Idle : Data ack'ed OR too many retries OR map lost
+    Data ack pending --> Deferring : Retry
+    Grant pending --> Idle : Tx resv. data w/o piggyback OR too many retries OR (TX frag w/o piggyback && Last)
+    Grant pending --> Deferring : Retry
+    Grant pending --> Data ack pending : Tx resv. request
+    Grant pending --> [*] : Tx resv. data w/piggyback
+    Grant pending --> [*] : Grant pending
+  
+```
+
+Transmission and deference state transition diagram showing four states: Idle, Deferring, Data ack pending, and Grant pending. Transitions are triggered by various conditions like queue status, retries, or specific data types (reserved, fragmented, or requested).
+
+**Figure IV.1 – Transmission and deference state transition diagram**
+
+#### IV.2 Variable definitions
+
+|             |                                                                     |
+|-------------|---------------------------------------------------------------------|
+| Start       | Data backoff start field from map "currently in effect"             |
+| End         | Data backoff end field from map "currently in effect"               |
+| Window      | Current backoff window                                              |
+| Random[n]   | Random number generator that selects a number between 0 and $n - 1$ |
+| Defer       | Number of transmit opportunities to defer before transmitting       |
+| Retries     | Number of transmissions attempted without resolution                |
+| Tx_time     | Saved time of when request or request/data was transmitted          |
+| Ack_time    | Ack time field from current map                                     |
+| Piggyback   | Flag set whenever a piggyback REQ is added to a transmit packet     |
+| Queue_Empty | Flag set whenever the data queue for this SID is empty              |
+| Lost_Map    | Flag set whenever a MAP is lost while in state data ack pending     |
+| my_SID      | Service ID of the queue that has a packet to transmit               |
+
+pkt size        Data packet size including MAC and physical-layer overhead (including piggyback if used)
+
+frag\_size      Size of the fragment
+
+Tx\_Mode       {Full\_Pkt; First\_Frag; Middle\_Frag; Last\_Frag}
+
+min\_frag      Size of the minimum fragment
+
+### IV.3 State examples
+
+#### IV.3.1 Idle – Waiting for a packet to transmit
+
+```
+Window = 0;
+Retries = 0;
+
+Wait for !Queue_Empty; /* Packet available to transmit */
+CalcDefer();
+go to Deferring
+```
+
+#### IV.3.2 Data ack pending – Waiting for data ack only
+
+```
+Wait for next Map;
+
+if (Data Acknowledge SID == my_SID)    /* Success! CMDS received data packet */
+    go to state Idle;
+else if (Ack_time > Tx_time)            /* COLLISION!!! or Pkt Lost or Map Lost */
+{
+    if (Lost_Map)
+        go to state Idle; /* Assume pkt was ack'ed to avoid sending
+duplicates */
+    else
+        Retry();
+}
+
+stay in state Data Ack Pending;
+```
+
+#### IV.3.3 Grant pending – Waiting for a grant
+
+```
+Wait for next Map;
+
+while (Grant SID == my_SID)
+    UtilizeGrant();
+
+if (Ack_time > Tx_time)    /* COLLISION!!!! or Request denied/lost or Map Lost */
+    Retry();
+stay in state Grant Pending
+```
+
+#### IV.3.4 Deferring – Determine proper transmission timing and transmit
+
+```
+if (Grant SID == my_SID)                    /* Unsolicited Grant */
+{
+    UtilizeGrant();
+}
+else if (unicast Request SID == my_SID)    /* Unsolicited Unicast Request */
+{
+    transmit Request in reservation;
+    Tx_time = time;
+
+    go to state Grant Pending;
+}
+else
+{
+    for (each Request or Request/Data Transmit Opportunity)
+    {
+```
+
+```
+
+        if (Defer != 0)
+            Defer = Defer - 1; /* Keep deferring until Defer = 0 */
+        else
+        {
+            if (Request/Data tx_op) and (Request/Data size >= pkt size)
+                /* Send data in contention */
+                {
+                    transmit data pkt in contention;
+                    Tx_time = time;
+
+                    if (Piggyback)
+                        go to state Grant Pending;
+                    else
+                        go to state Data Ack Pending;
+                }
+            else                /* Send Request in contention */
+                {
+                    transmit Request in contention;
+                    Tx_time = time;
+
+                    go to state Grant Pending;
+                }
+        }
+    }
+}
+
+```
+
+Wait for next Map;  
+STAY IN STATE DEFERRING
+
+## IV.4 Function examples
+
+### IV.4.1 CalcDefer() – Determine defer amount
+
+```
+
+if (Window < Start)
+    Window = Start;
+
+if (Window > End)
+    Window = End;
+
+Defer = Random[2^Window];
+
+```
+
+### IV.4.2 UtilizeGrant() – Determine best use of a grant
+
+```
+
+if (Grant size >= pkt size)                /* CM can send full pkt */
+{
+    transmit packet in reservation;
+    Tx_time = time;
+    Tx_mode = Full_pkt;
+
+    if (Piggyback)
+        go to state Grant Pending;
+    else
+        go to state Idle;
+}
+else if (Grant size < min_frag && Grant Size > Request size)
+    /* Can't send fragment, but can send a Request */
+{
+    transmit Request in reservation;
+    Tx_time = time;
+    go to state Grant Pending;
+}
+else if (Grant size == 0)                /* Grant Pending */
+    go to state Grant Pending;
+else
+{
+
+```
+
+```
+
+while (pkt_size > 0 && Grant SID == my_SID)
+{
+    if (Tx_mode == Full_Pkt)
+        Tx_mode = First_frag;
+    else
+        Tx_mode = Middle_frag;
+
+    pkt_size = pkt_size - frag_size;
+    if (pkt_size == 0)
+        Tx_mode = Last_frag;
+
+    if (another Grant SID == my_SID) /* multiple grant mode */
+        piggyback_size = 0
+    else
+        piggyback_size = pkt_size    /* piggyback mode */
+
+    if (piggyback_size > 0)
+        transmit fragment with piggyback request for remainder of packet
+in reservation
+    else
+        transmit fragment in reservation;
+}
+go to state Grant Pending;
+}
+
+```
+
+#### IV.4.3 Retry()
+
+```
+
+Retries = Retries + 1;
+if (Retries > 16)
+{
+    discard pkt, indicate exception condition
+    go to state Idle;
+}
+
+Window = Window + 1;
+
+CalcDefer();
+
+go to state Deferring;
+
+```
+
+## Appendix V
+
+### IGMP example
+
+(This appendix does not form an integral part of this Recommendation)
+
+Clause 5.3.1 defines the requirements for CMTS and CM support of IGMP signalling. This appendix provides an example CM passive-mode state machine for maintaining membership of a single multicast group.
+
+![State machine diagram for IGMP support - CM passive mode. The diagram shows three states: Idle (no members), Joining, and Joined. Transitions are labeled with events and actions (E/A).](dae67d96f5906c2a1ab09497840f2df8_img.jpg)
+
+```
+stateDiagram-v2
+    [*] --> Idle
+    Idle --> Joining : E1/A1
+    Joining --> Idle : E6/A7
+    Joining --> Joined : E4/A6
+    Joined --> Idle : E5/A7
+    Joined --> Joining : E2/A4
+    Joined --> Idle : E6/A7
+    Joined --> Joining : E1/A3
+    Joined --> Idle : E3/A5
+    Joining --> Joining : E1/A2
+```
+
+The diagram illustrates a state machine with three states: Idle (no members), Joining, and Joined. Transitions are labeled with events and actions (E/A). The Idle state is the initial state. Transitions from Idle to Joining are triggered by E1/A1. Transitions from Joining to Idle are triggered by E6/A7. Transitions from Joining to Joined are triggered by E4/A6. Transitions from Joined to Idle are triggered by E5/A7, E6/A7, and E3/A5. Transitions from Joined to Joining are triggered by E2/A4 and E1/A3. There is a self-loop transition on the Joining state triggered by E1/A2.
+
+State machine diagram for IGMP support - CM passive mode. The diagram shows three states: Idle (no members), Joining, and Joined. Transitions are labeled with events and actions (E/A).
+
+Figure V.1 – IGMP support – CM passive mode
+
+#### V.1 Events
+
+E1: MR received on CPE I/f
+
+E2: M1 timer expired
+
+E3: MQ received on RF I/f
+
+E4: MR received on RF I/f
+
+E5: M2 timer expired
+
+E6: Auth failure<sup>31</sup>
+
+<sup>31</sup> SA-MAP response returns an error code of 7, "not authorized for requested downstream traffic flow".
+
+## V.2 Actions
+
+- A1: MQI = 125 s; QRI = 10 s; start M1 timer with random value between 0 and 3 s; start M2 timer =  $2 \times \text{MQI} + \text{QRI}$ ; start TEK machine, if necessary<sup>32</sup>; add multicast addr to multicast filter
+- A2: Discard MR packet
+- A3: Reset M2 timer =  $2 \times \text{MQI} + \text{QRI}$ ; start M1 timer with random value between 0 and 3 s
+- A4: Transmit MR on RF I/f; set I = current time
+- A5: Recompute MQI =  $\text{MAX}(125, \text{current time} - I)$ ; set I = current time, forward MQ on CPE I/f
+- A6: Cancel M1 timer
+- A7: Delete multicast addr from multicast filter
+
+---
+
+<sup>32</sup> If the multicast traffic is encrypted, a TEK machine needs to be started to decrypt the encrypted multicast packets. To determine whether the multicast is encrypted, the CM makes a SA-MAP request to the CMTS to get the associated SAID of the multicast group address. If the SA-MAP response returns an SAID, then a TEK machine is started. No TEK machine is necessary if the SA-MAP response indicates that the multicast traffic is not encrypted. The SA-MAP response may also indicate that the CM is not authorized to receive this multicast traffic. In such a case, the CM terminates the multicast state machine and stops forwarding the multicast traffic.
+
+## Appendix VI
+
+### Unsolicited grant services
+
+(This appendix does not form an integral part of this Recommendation)
+
+This appendix discusses the intended use of the unsolicited grant service (UGS) and unsolicited grant service with activity detection (UGS-AD) and includes specific examples.
+
+#### VI.1 Unsolicited grant service (UGS)
+
+##### VI.1.1 Introduction
+
+Unsolicited grant service is an upstream flow scheduling service type that is used for mapping constant bit rate (CBR) traffic onto service flows. Since the upstream is scheduled bandwidth, a CBR service can be established by the CMTS scheduling a steady stream of grants. These are referred to as unsolicited because the bandwidth is predetermined, and there are no ongoing requests being made.
+
+The classic example of a CBR application of interest is voice over Internet Protocol (VoIP) packets. Other applications are likely to exist as well.
+
+Upstream flow scheduling services are associated with service flows, each of which is associated with a single service ID (SID). Each service flow may have multiple classifiers. Each classifier may be associated with a unique CBR media stream. Classifiers may be added and removed from a service flow. Thus, the semantics of UGS must accommodate single or multiple CBR media streams per SID.
+
+For the discussion within this appendix, a subflow will be defined as the output of a classifier. Since a VoIP session is identified with a classifier, a subflow in this context refers to a VoIP session.
+
+##### VI.1.2 Configuration parameters
+
+- Nominal grant interval.
+- Unsolicited grant size.
+- Tolerated grant jitter.
+- Grants per interval.
+
+Explanations of these parameters and their default values are provided in Annex C.
+
+##### VI.1.3 Operation
+
+When a service flow is provisioned for UGS, the nominal grant interval is chosen to equal the packet interval of the CBR application. For example, VoIP applications with 10-ms packet sizes will require a nominal grant interval of 10 ms. The size of the grant is chosen to satisfy the bandwidth requirements of the CBR application and relates directly to the length of the packet.
+
+When multiple subflows are assigned to a UGS service, multiple grants per interval are issued. There is no explicit mapping of subflows to grants. The multiple grants per interval form a pool of grants in which any subflow can use any grant.
+
+It is assumed in this operational example the default UGS case of no concatenation and no fragmentation.
+
+##### VI.1.4 Jitter
+
+Figure VI.1 shows the relationship between grant interval and tolerated grant jitter, and shows an example of jitter on subflows.
+
+![Figure VI.1: Example jitter with multiple grants per SID. The diagram shows three consecutive nominal grant intervals. Each interval has a 'Max tolerated jitter' window. Grants are represented by black bars. In the first interval, grants 1, 2, and 3 are shown. In the second interval, grants 1 and 2 are shown, with grant 1 occurring at t_i' and grant 2 at t_i + jitter. In the third interval, grants 4, 1, and 2 are shown. The time axis is marked with t_0, t_i, t_i', and t_i + jitter. The label J.122_FVI-1 is in the bottom right corner.](67f1290c75b9e4a4a36af1afacbb7932_img.jpg)
+
+Figure VI.1: Example jitter with multiple grants per SID. The diagram shows three consecutive nominal grant intervals. Each interval has a 'Max tolerated jitter' window. Grants are represented by black bars. In the first interval, grants 1, 2, and 3 are shown. In the second interval, grants 1 and 2 are shown, with grant 1 occurring at t\_i' and grant 2 at t\_i + jitter. In the third interval, grants 4, 1, and 2 are shown. The time axis is marked with t\_0, t\_i, t\_i', and t\_i + jitter. The label J.122\_FVI-1 is in the bottom right corner.
+
+**Figure VI.1 – Example jitter with multiple grants per SID**
+
+For only one grant per interval, the tolerated grant jitter is the maximum difference between the actual grant time ( $t_i'$ ) and the nominal grant time ( $t_i$ ). For multiple grants per interval, the tolerated grant jitter is the maximum difference between the actual time of the last grant in the group of grants and the nominal grant time ( $t_i$ ). If the arrival of any grant is at  $t_i'$ , then  $t_i \leq t_i' \leq t_i + \text{jitter}$ .
+
+Figure VI.1 demonstrates how a subflow will be jittered even though the individual grants may not move from their relative position. During the first interval, three VoIP sessions are established, and they happen to fall on the three grants. In the second interval, VoIP session 3 has been torn down. Since the CMTS does not know which subflow is associated with which grant, it decides to remove the first grant. The remaining two calls shift to the other two grants. In the third interval, a new VoIP session 4 and a new grant have been added. The new call happens to fall on the new grant. The net effect is that the subflows may move around within their jitter interval.
+
+The advantage of a small jitter interval is that the VoIP receive jitter buffer may be kept small. The disadvantage is that this places a scheduling constraint on the CMTS.
+
+The boundary of a nominal grant interval is arbitrary and is not communicated between the CMTS and the CM.
+
+NOTE – More dramatic events, like the loss of a downstream MAP or the frequency hopping of an upstream, may cause subflows to jitter outside of this jitter window.
+
+### VI.1.5 Synchronization issues
+
+There are two synchronization problems that occur when carrying CBR traffic such as VoIP sessions across a network. The first is a frequency mismatch between the source clock and the destination clock. This is managed by the VoIP application, and is beyond the scope of this Recommendation. The second is the frequency mismatch between the CBR source/sinks, and the bearer channel that carries them.
+
+Specifically, if the clock that generates the VoIP packets towards the upstream is not synchronized with the clock at the CMTS that is providing the UGS service, the VoIP packets may begin to accumulate in the CM. This could also occur if a MAP was lost, causing packets to accumulate.
+
+When the CM detects this condition, it asserts the queue indicator in the service flow EH element. The CMTS will respond by issuing an occasional extra grant so as to not exceed 1% of the provisioned bandwidth (this corresponds to a maximum of one extra grant every one hundred grants). The CMTS will continue to supply this extra bandwidth until the CM deasserts this bit.
+
+A similar problem occurs in the downstream. The far-end transmitting source may not be frequency-synchronized to the clock that drives the CMTS. Thus, the CMTS SHOULD police at a rate slightly higher than the exact provisioned rate to allow for this mismatch and to prevent delay buildup or packet drops at the CMTS.
+
+## **VI.2 Unsolicited grant service with activity detection (UGS-AD)**
+
+### **VI.2.1 Introduction**
+
+Unsolicited grant service with activity detection (UGS-AD) is an upstream flow scheduling service type. This clause describes one application of UGS-AD, which is the support for voice activity detection (VAD). VAD is also known as silence suppression and is a voice technique in which the transmitting CODEC sends voice samples only when there is significant voice energy present. The receiving CODEC will compensate for the silence intervals by inserting silence or comfort noise equal to the perceived background noise of the conversation.
+
+The advantage of VAD is the reduction of network bandwidth required for a conversation. It is estimated that 60% of a voice conversation is silence. With that silence removed, that would allow a network to handle substantially more traffic.
+
+Subflows in this context will be described as active and inactive. Both of these states are within the MAC layer QOS state known as active.
+
+### **VI.2.2 MAC configuration parameters**
+
+The configuration parameters include all of the normal UGS parameters, plus:
+
+- nominal polling interval;
+- tolerated poll jitter.
+
+Explanation of these parameters and their default values are provided in Annex C.
+
+### **VI.2.3 Operation**
+
+When there is no activity, the CMTS sends polled requests to the CM. When there is activity, the CMTS sends unsolicited grants to the CM. The CM indicates the number of grants per interval that it currently requires in the active grant field of the UGSH in each packet of each unsolicited grant. The CM may request up to the maximum active grants per interval. The CM constantly sends this state information so that no explicit acknowledgment is required from the CMTS.
+
+It is left to the implementation of the CM to determine activity levels. Implementation options include:
+
+- Having the MAC layer service provide an activity timer per classifier. The MAC layer service would mark a subflow inactive if packets stopped arriving for a certain time, and mark a subflow active the moment a new packet arrived. The number of grants requested would equal the number of active subflows.
+- Having a higher layer service entity, such as an embedded media client, which indicates activity to the MAC layer service.
+
+When the CM is receiving polled requests and it detects activity, the CM requests enough bandwidth for one grant per interval. If activity is for more than one subflow, the CM will indicate this in the active grant field of the UGSH beginning with the first packet it sends.
+
+When the CM is receiving unsolicited grants, then detects new activity, and asks for one more grant, there will be a delay in time before it receives the new grant. During that delay, packets may build up at the CM. When the new unsolicited grant is added, the CMTS will burst extra grants to clear out the packet buildup.
+
+When the CM is receiving unsolicited grants, then detects inactivity on a subflow and asks for one less grant, there will be a delay in time before the reduction in grants occurs. If there has been any build up of packets in the upstream transmit queue, the extra grants will reduce or empty the queue. This is fine, and keeps system latency low. The relationship of which subflow is getting which specific grant will also change. This effect appears as low-frequency jitter that the far end must manage.
+
+When the CM is receiving unsolicited grants and detects no activity on any of its subflows, it will send one packet with the active grants field of the UGSH set to zero grants, and then cease transmission. The CMTS will switch from UGS mode to real time polling mode. When activity is again detected, the CM sends a request in one of these polls to resume delivery of unsolicited grants. The CMTS ignores the size of the request and resumes allocating grant size grants to the CM.
+
+It is not necessary for the CMTS to separately monitor packet activity since the CM does this already. In the worst case, if the CMTS misses the last packet that indicated zero grants, the CMTS and CM would be back in sync at the beginning of the next talk spurt. Because of this scenario, when the CM goes from inactive to active, the CM must be able to restart transmission with either polled requests or unsolicited grants.
+
+#### VI.2.4 Example
+
+![Figure VI.2 – VAD start-up and stop. A timeline diagram showing the sequence of events for a voice call. The horizontal axis represents time in milliseconds (ms) from 0 to 50. The vertical axis lists several components: Voice, G.711 CODEC, Tx queue, Polled requests, Unsolicited grants, Data on upstream, and Playout. The diagram illustrates the start-up phase where voice packets are generated, queued, and then granted for transmission. The Playout section shows the first packet being played out after a 20 ms jitter buffer is filled.](dfff128799eae85af7d5ba537f31d560_img.jpg)
+
+The diagram illustrates the VAD start-up and stop process over a 50 ms timeline. 
+   
+• **Voice:** A continuous bar from 0 ms to approximately 30 ms.
+   
+• **G.711 CODEC:** Shows three packets generated at 0, 10, and 20 ms. The first packet (0-10 ms) is shaded.
+   
+• **Tx queue:** Shows three packets entering the queue at 10, 20, and 30 ms.
+   
+• **Polled requests:** A series of vertical lines representing polling intervals. The first poll is at approximately 15 ms.
+   
+• **Unsolicited grants:** Grants are issued at 30, 35, 40, and 45 ms.
+   
+• **Data on upstream:** Packets are shown arriving at the upstream at 30, 35, 40, and 45 ms.
+   
+• **Playout:** The first packet (0-10 ms) is played out starting at 30 ms. The second packet (10-20 ms) is played out starting at 35 ms. The third packet (20-30 ms) is played out starting at 40 ms. The first packet is shaded in the playout section.
+   
+A label 'J.122\_FVI-2' is present in the bottom right corner of the diagram area.
+
+Figure VI.2 – VAD start-up and stop. A timeline diagram showing the sequence of events for a voice call. The horizontal axis represents time in milliseconds (ms) from 0 to 50. The vertical axis lists several components: Voice, G.711 CODEC, Tx queue, Polled requests, Unsolicited grants, Data on upstream, and Playout. The diagram illustrates the start-up phase where voice packets are generated, queued, and then granted for transmission. The Playout section shows the first packet being played out after a 20 ms jitter buffer is filled.
+
+**Figure VI.2 – VAD start-up and stop**
+
+Figure VI.2 shows an example of a single G.711 (64 kbit/s) voice call with a packet size of 10 ms, and a receive jitter buffer that requires a minimum of 20 ms of voice (thus, 2 packets) before it will begin playout.
+
+Assume voice begins at time zero. After a nominal processing delay and a 10-ms packetization delay, the DSP CODEC generates voice packets that are then transferred to the upstream transmit queue. The next polled request is used, which results in the start of the unsolicited grants some time later. Additional unsolicited grants are immediately issued to clear out the upstream queue.
+
+These packets traverse the network and arrive at the receive jitter buffer. The 20-ms minimum jitter buffer is met when the second packet arrives. Because the packets arrive close together, only an additional few milliseconds of latency is been added. After a nominal processing delay, playout begins.
+
+When the voice spurt ends, the CM sends one remaining packet with no payload and with the active grants field of the UGSH set to zero grants. Some time later, UGS stops, and real-time polling begins.
+
+### VI.2.5 Talk spurt grant burst
+
+The extra burst of unsolicited grants when a flow becomes active is necessary because the jitter buffer at the receiving CODEC typically waits to have a minimum amount of voice samples before beginning the playout. Any delay between the arrival of these initial packets will add to the final latency of the phone call. Thus, the sooner the CMTS recognizes that the CM has packets to send and can empty the CM's buffer, the sooner those packets will reach the receiver, and the lower the latency that will be incurred in the phone call.
+
+It is an indeterminate problem as to how many grants must be burst. When the CM makes its request for an additional grant, one voice packet has already accumulated. The CM has no idea how many extra grants to request as it has no idea of the round-trip response time it will receive from the CMTS, and thus how many packets may accumulate. The CMTS has a better idea, although it does not know the far-end jitter buffer requirements.
+
+The solution is for the CMTS to choose the burst size, and burst these grants close together at the beginning of the talk spurt. This occurs when moving from real-time polling to UGS, and when increasing the number of UGS grants per interval.
+
+A typical start-up latency that will be introduced by the request to grant response time is shown in Table VI.1.
+
+**Table VI.1 – Example request to grant response time**
+
+| Variable |                                                                                                                       | Example value |
+|----------|-----------------------------------------------------------------------------------------------------------------------|---------------|
+| 1        | The time taken from the voice packet being created to the time that voice packet arrives in the CM upstream queue.    | 0-1 ms        |
+| 2        | The time until a polled request is received. The worst case time is the polled request interval.                      | 0-5 ms        |
+| 3        | The request-grant response time of the CMTS. This value is affected by MAP length and the number of outstanding MAPS. | 5-15 ms       |
+| 4        | The round-trip delay of the HFC plant, including the downstream interleaving delay.                                   | 1-5 ms        |
+| Total    |                                                                                                                       | 6-26 ms       |
+
+This number will vary between CMTS implementations, but a reasonable number of extra grants to expect from the example above would be:
+
+**Table VI.2 – Example extra grants for new talk spurts**
+
+| UGS interval | Extra grants for new talk spurts |
+|--------------|----------------------------------|
+| 10 ms        | 2                                |
+| 20 ms        | 1                                |
+| 30 ms        | 0                                |
+
+Once again, it is worth noting that the CMTS and CM cannot and do not associate individual subflows with individual grants. That means that when current subflows are active and a new subflow becomes active, the new subflow will immediately begin to use the existing pool of grants. This potentially reduces the start-up latency of new talk spurts, but increases the latency of the other subflows. When the burst of grants arrives, it is shared with all the subflows, and restores or even reduces the original latency. This is a jitter component. The more subflows that are active, the less impact that adding a new subflow has.
+
+### **VI.2.6 Admission considerations**
+
+Note that when configuring the CMTS admission control, the following factors must be taken into account.
+
+VAD allows the upstream to be over-provisioned. For example, an upstream that might normally handle 24 VoIP sessions might be over-provisioned by as much as 36 (50%) or even 48 (100%). Whenever there is over-provisioning, there exists the statistical possibility that all upstream VoIP sessions may become active. At that time, the CMTS may be unable to schedule all the VoIP traffic. Additionally, the talk spurt grant bursts would be stretched out. CM implementations of VAD should recognize this possibility, and set a limit as to how many packets they will allow to accumulate on its queue.
+
+Occasional saturation of the upstream during VAD can be eliminated by provisioning the maximum number of permitted VoIP sessions to be less than the maximum capacity of the upstream with all voice traffic (24 in the previous example). VAD would cause the channel usage to drop from 100% to around 40% for voice, allowing the remaining 60% to be used for data and maintenance traffic.
+
+## Appendix VII
+
+### S-CDMA framing
+
+(This appendix does not form an integral part of this Recommendation)
+
+This appendix is informative. In case of conflict between this appendix and any normative part of this Recommendation, the normative part takes precedence.
+
+Please note that the pseudo-code below is specific to the case of a single burst using all spreading codes.
+
+#### VII.1 Coded subsymbol numbering
+
+The following code sample contains a short algorithmic description of the operation of the address generator for the coded subsymbols. The address generator for the coded subsymbols fills rows first using the interleaver step size parameter (step in the listing) to step through the spreading intervals within a row. Each step is performed using a modified modulo algorithm that allows the use of interleaver step size and spreading intervals per frame with common divisors. After each row is filled, the next row is begun with the first spreading interval. In the following listings, the index "i" is initialized to the value "1" and coded\_col0 is defined as "0".
+
+```
+for( row = FIRST_ROW; row <= LAST_ROW; row++ )
+{
+    coded_col = 0;
+    store_coded( row, coded_col );
+    /* Store the coded portion of the symbol (or preamble) to (row,coded_col)
+*/
+    for( i = 1; i < framelen; i++ )
+    {
+        coded_col = coded_col + Interleaver_step_size;
+
+        if( mod( i, framelen / gcd( step, framelen ) ) == 0 )
+            coded_col = coded_col + 1; /* gcd is greatest common divisor */
+
+        coded_col = mod( coded_col, framelen );
+        store_coded( row, coded_col );
+        /* Store the coded portion of the symbol (or preamble) to
+(row,coded_col) */
+    }
+}
+```
+
+#### VII.2 Uncoded subsymbol numbering
+
+The following is a short algorithmic description of the operation of the address generator for uncoded subsymbols. The generator fills columns within a subframe first. The row index increments by one for each uncoded subsymbol. At the end of the subframe, the column index is incremented and the row index set to the first row of the subframe. After completing a subframe, the next subframe begins with the next uncoded subsymbol.
+
+```
+uncoded_col = 0;
+UNCODED_ROW = FIRST_ROW;
+while( uncoded_row <= LAST_ROW )
+{
+    if( ( uncoded_row + R ) > LAST_ROW )
+        Rprime = LAST_ROW - uncoded_row + 1;
+    else
+        Rprime = R;
+
+    for( i = 0; i < Rprime; i++ )
+```
+
+```
+
+{
+    /* Check whether (uncoded_row,uncoded_col) is a preamble location.
+     * If it is, go to next location */
+    if( not_preamble( uncoded_row, uncoded_col ) )
+        store_uncoded( uncoded_row, uncoded_col, unc_sym );
+    uncoded_row = uncoded_row + 1;
+}
+
+uncoded_row = uncoded_row - Rprime;
+uncoded_col = uncoded_col + 1;
+if (uncoded_col >= framelen)
+{
+    uncoded_col = 0;
+    uncoded_row = uncoded_row + R;
+}
+}
+
+```
+
+FIRST\_ROW and LAST\_ROW are, respectively, the first and last row (i.e., code) in each frame spanned by the grant. FIRST\_ROW can be between 0 and 127 in the first frame of the allocation and is 0 in any other frames that the grant may span (if any). LAST\_ROW can be between 0 to 127 in the last frame of the burst and is 127 for any other frame (if any).
+
+### VII.3 Framer output numbering
+
+The following code sample contains a short algorithmic description of the operation of the address generator for the output symbols. The address generator for the output symbols is used to access both the coded and uncoded subsymbol memories. The output address generator accesses all of the rows (codes) of a spreading interval first followed by subsequent spreading intervals.
+
+```
+
+for( col=0; col < framelen; col++ )
+    for( row=0; row < ACTIVE_CODES; row++ )
+        outsym = get_data( row, col );
+
+```
+
+### VII.4 Comments
+
+In all of the samples, the number of iterations for the loop is not always correct since an allocation can be less than the number of codes. In clause VII.2, the listing supports the case of a shortened subframe.
+
+## Appendix VIII
+
+### Ambient temperature and wind loading effects
+
+(This appendix does not form an integral part of this Recommendation)
+
+This appendix discusses possible ambient temperature change and dynamic wind loading effects relevant to operating a system with DOCS 2.0 CMs and CMTSs. The intent of this appendix is to describe possible approaches for dealing with these issues. The relationships between the timing variation of the received upstream signal and the rate of change of these ambient plant conditions are discussed. However, measured field data providing the statistics of the ambient conditions used in these relationships is not available, so it is not possible at the time of writing to determine the magnitude or frequency of occurrence of these conditions on operational cable systems. This appendix is not intended to be an exhaustive discussion of either these issues or solutions.
+
+The following issues are discussed in this appendix:
+
+- synchronization tolerances to plant delay variations;
+- changes in propagation delay due to temperature changes;
+- changes in propagation delay due to wind, in the case of aerial cable plant.
+
+#### VIII.1 Synchronization tolerances to plant delay variations
+
+The CMTS receiver synchronization requirements for S-CDMA and advanced TDMA are identical for the same signal constellation and symbol rates. However, for S-CDMA, burst synchronization is accomplished to a fine degree through the ranging process, while for TDMA, burst synchronization is accomplished to a coarse degree through the ranging process and then to a fine degree through a receiver burst timing recovery process. In both cases, the degree of timing accuracy required in the receiver is tighter for higher symbol rates and higher-order constellations.
+
+Because S-CDMA requires a fine degree of timing accuracy to be accomplished solely by the ranging process, it is more sensitive to changes in the propagation delay of the cable plant between ranging intervals, which can be as much as 30 seconds apart. Table VIII.1 lists plant delay variations that can be accommodated in S-CDMA and TDMA modes for a 1-dB degradation under example conditions.
+
+**Table VIII.1 – Allowable plant timing drift**
+
+| Constellation     | $E_s/N_0$ for 1e-8 BER (dB) | Allowable peak-to-peak plant delay variation (ns) S-CDMA mode | Allowable peak-to-peak plant delay variation (ns) TDMA mode |
+|-------------------|-----------------------------|---------------------------------------------------------------|-------------------------------------------------------------|
+| Fully-coded QPSK  | 5                           | 90                                                            | 800                                                         |
+| TCM QPSK          | 9                           | 79                                                            | N/A                                                         |
+| TCM 8QAM          | 12                          | 57                                                            | N/A                                                         |
+| Uncoded QPSK      | 15                          | 38                                                            | 800                                                         |
+| Fully-coded 64QAM | 17.7                        | 24                                                            | 800                                                         |
+| TCM 32QAM         | 19                          | 18                                                            | N/A                                                         |
+| Uncoded 16QAM     | 22                          | 9                                                             | 800                                                         |
+| Uncoded 32QAM     | 25                          | 6                                                             | 800                                                         |
+| TCM 128QAM        | 25                          | 6                                                             | N/A                                                         |
+| Uncoded 64QAM     | 28                          | 2                                                             | 800                                                         |
+
+Defined conditions:
+
+- 1 dB degradation at 1e-8 BER;
+- uniform ranging offset over  $\pm 1/64$  chip;
+- 63 CMs, each with 2 codes;
+- $E_s/N_0$  numbers are ideal theoretical values, not including implementation effects;
+- 5.12 MHz modulation rate;
+- Timing variation over 30-second period;
+- TDMA receiver accepts  $\pm 2$  symbol coarse timing offset (implementation-dependent).
+
+This channel impairment should be considered along with all of the other upstream channel characteristics highlighted in Table 4-2.
+
+DOCS requires station maintenance at least every 30 seconds (T4 time-out has a maximum value of 35 seconds). For S-CDMA at a given modulation and symbol rate, if there exists a rapid propagation delay variation such that the resulting delay change cannot be tracked by station maintenance, then one or more of the following performance trade-offs and/or system changes may be enacted:
+
+- 1) decrease the station maintenance period;
+- 2) decrease the constellation order;
+- 3) decrease the modulation rate;
+- 4) apply additional error correction;
+- 5) apply some combination of 1 through 4; or
+- 6) change the channel to operate in advanced TDMA mode.
+
+The following clauses discuss the relationship of temperature changes and wind loading on the propagation delay in coaxial and HFC cable plants.
+
+## **VIII.2 Change in propagation delay due to temperature changes**
+
+### **VIII.2.1 Fibre delay changes due to temperature**
+
+In HFC plant design, the number of amplifiers in cascade in the coax portion is kept low in order to keep signal degradation to an acceptable level. As a result, long runs of cable plant are mainly comprised of fibre. A typical value for propagation delay variation due to temperature change of the fibre is 44 picoseconds per km per degree C [b-TRISCHITTA]. The delay variation comes mostly from the change in refractive index of the glass with temperature, not the change in fibre length.
+
+It is assumed that changes in optical cable length due to stretching or expansion will be a negligible factor because optical cables are built to isolate the fibre from stresses in the cable itself. The fibre usually sits loosely in a tube inside the cable and considerable relative movement is possible. This construction allows normal cable handling and aerial deployment without resulting in high stress on the optical fibre.
+
+Assuming 44 picoseconds per km per degree C, any product of optical cable length and temperature change that equals 50 results in approximately a 2-nanosecond change in the fibre propagation delay. For example, 25-km fibre and a 2-degree temperature change will result in a 2-ns change in propagation delay. For the maximum distance between CMTS and CM specified in DOCS of 100 miles, or roughly 160 km, the temperature change needed for a 2-ns second change in one-way propagation delay is 0.3 degree C.
+
+Obviously, the issue is how fast the cable core (where the fibre is) will heat up under ambient temperature changes. For buried or underground cable, there is no issue. For aerial cable, solar loading changes should be considered. Black sheathed cable has interior temperatures considerably
+
+higher than ambient temperatures in sunlight, but data is currently unavailable. When the rising sun hits aerial cable on a cold morning, one would expect a temperature change. Similarly, sunlight appearing out of cloud cover may have a similar impact, although the size of the shadow of the cloud moving out of the way has to be considered. The numerical examples above suggest that only long aerial cable runs may have a problem under some combinations of time-of-day and weather.
+
+### **VIII.2.2 Coaxial cable delay changes due to temperature**
+
+The coaxial cable has a blown foam between the centre conductor and the solid shield, and nominal propagation velocity is about 87% of free space velocity according to one manufacturer. Propagation velocity does not vary markedly with temperature.
+
+Given the relatively short lengths of coaxial cable in most HFC plant (a few miles), this seems unlikely to be a significant source of delay variation.
+
+### **VIII.2.3 Delay change due to wind**
+
+Aerial cable stretches with wind loading, so it is possible to estimate a propagation delay from the change in length under various wind loads. As mentioned, the construction of optical cable makes it tolerant of stretching, so it is assumed that optical cable stretching due to wind loading can be ignored. Wind loading will affect aerial coaxial cables.
+
+Wind loading is difficult to deal with analytically because it is unlikely to be uniform along the cable. A delay model derived from a significant body of measured data is needed to investigate this further. Wind loading may be a source of fast delay variation and station maintenance may not occur at intervals small enough for the ranging mechanism to track this variation accurately.
+
+The effects of wind loading on typical cable was investigated with a programme from a coaxial cable manufacturer. These calculations showed that length changes in the range 0.01% to 0.05% are possible for various amounts of wind loading. This converts to significant propagation delay variation. As an example, with 5 miles (8 km) and 0.02% length variation, the change in propagation delay is:
+
+$$\frac{8 \text{ km}}{3 \times 10^5 \text{ km/s}} \times \frac{1}{0.87} \times 2 \times 10^{-4} = 6 \text{ ns}$$
+
+This is a peak value, but the length of coax is quite short and the wind load is moderate. While the time duration over which this delay variation occurs is unspecified, it may be noted that wind gust data is readily available for most cities, and wind gust will be the primary mechanism for wind-based timing changes on cable plants. For example, in New York City at the time of writing, wind gusts of up to 40 mph are reported, while average wind speed is about 10 mph. Hence, over a period of 1 to 4 seconds (the typical wind gust measurement interval), the wind speed changes by 30 mph. Much stronger wind gusts are frequently measured in locations prone to windy conditions.
+
+## Bibliography
+
+- [b-Cab 960702] CableLabs SP-CMTS-NSII01-960702 (1996), *Data-Over-Cable Service Interface Specifications: Cable Modem Termination System – Network Side Interface Specification*.
+- [b-Cab 010829] CableLabs SP-CMCI-I06-010829 (2001), *Data-Over-Cable Service Interface Specifications: Cable Modem to Customer Premise Equipment Interface Specification*.
+- [b-ETSI EG 201 212] ETSI EG 201 212 (1998), *Electrical safety; Classification of interfaces for equipment to be connected to telecommunication networks*. (Also available from CENELEC as ROBT-002.)
+- [b-EN 50081-1] CENELEC EN 50081-1 (1992), *Electromagnetic compatibility – Generic emission standard – Part 1: Residential, commercial, and light industry*.
+- [b-EN 50082-1] CENELEC EN 50082-1 (1997), *Electromagnetic compatibility – Generic immunity standard – Part 1: Residential, commercial, and light industry*.
+- [b-EN 50083-1] CENELEC EN 50083-1 (1993), *Cabled networks for television signals, sound signals, and interactive services – Part 1: Safety requirements*.
+- [b-EN 50083-2] CENELEC EN 50083-2 (1995), *Cabled networks for television signals, sound signals, and interactive services – Part 2: Electromagnetic compatibility for equipment*.
+- [b-EN 50083-7] CENELEC EN 50083-7 (1996), *Cabled networks for television signals, sound signals, and interactive services – Part 7: System performance*.
+- [b-EN 50083-10] CENELEC EN 50083-10 (1999), *Cabled networks for television signals, sound signals, and interactive services – Part 10: System performance for return paths*.
+- [b-EN 60950] CENELEC EN 60950 (1992), *Specification for safety of information technology equipment*.
+- [b-US 47CFR 18.305] *Code of Federal Regulations*, Title 47, Parts 15 and 76, October 2000.
+- [b-CommScope] CommScope catalog for Parameter III cable (QR cable is listed as 88%).
+- [b-ISO/IEC 10038] ISO/IEC 10038:1993, *Information Technology – Telecommunications and information exchange between systems – Local area networks – Media access control (MAC) bridges*.
+- [b-RFC 1700] IETF RFC 1700 (1994), *Assigned Numbers*.
+- [b-RFC 2210] IETF RFC 2210 (1997), *The Use of RSVP with the IETF Integrated Services*.
+- [b-RFC 2211] IETF RFC 2211 (1997), *Specification of the Controlled-Load Network Element Service*.
+- [b-TRISCHITTA] TRISCHITTA (P.R.), VARMA (E.L.): *Jitter in Digital Transmission Systems*, Artech House, Norwood, MA, 1989.
+
+- [b-SpanMaster] SpanMaster: available at  
+[www.commscope.com/html/community\\_access\\_cable.shtml](http://www.commscope.com/html/community_access_cable.shtml).
+- [b-VCCI-1] Voluntary Control Council for Interference by Information Technology Equipment (VCCI-1):  
+[http://www.vcci.or.jp/vvci\\_e/index.html](http://www.vcci.or.jp/vvci_e/index.html).
+- [b-Ethernet] Ethernet Protocol Version 2.0, Digital, Intel, Xerox, 1982.
+
+
+
+## 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.126**
+
+(12/2007)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Interactive systems for digital television distribution
+
+# --- **Embedded Cable Modem device specification**
+
+ITU-T Recommendation J.126
+
+
+
+## ITU-T Recommendation J.126
+
+# Embedded Cable Modem device specification
+
+## Summary
+
+ITU-T Recommendation J.126 defines additional features that must be added to a Cable Modem for implementations that embed the Cable Modem with another application, such as an IPCablecom multimedia terminal adapter (MTA).
+
+## Source
+
+ITU-T Recommendation J.126 was approved on 14 December 2007 by ITU-T Study Group 9 (2005-2008) under the ITU-T Recommendation A.8 procedure.
+
+## History
+
+| Edition |       | Approval   |
+|---------|-------|------------|
+| 1.0     | J.126 | 2004-04-22 |
+| 2.0     | J.126 | 2007-12-14 |
+
+## 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2008
+
+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    |
+| 2.1 Normative references.....                                                              | 1    |
+| 2.2 Informative references.....                                                            | 2    |
+| 3 Definitions .....                                                                        | 3    |
+| 4 Abbreviations and conventions.....                                                       | 4    |
+| 4.1 Abbreviations .....                                                                    | 4    |
+| 4.2 Conventions.....                                                                       | 6    |
+| 5 Embedded cable modem.....                                                                | 6    |
+| 5.1 Device interface reference model.....                                                  | 6    |
+| 5.2 eDOCSIS requirements .....                                                             | 14   |
+| Annex A – SLED MIB definition.....                                                         | 39   |
+| Annex B – eSAFE MIB Definition.....                                                        | 44   |
+| Annex C – Format and content for eCM/eSTB event, SYSLOG, and SNMP trap<br>extensions ..... | 55   |
+
+
+
+# Embedded Cable Modem device specification
+
+# 1 Scope
+
+This Recommendation defines additional features that must be added to a Cable Modem for implementations that embed the Cable Modem with another application, such as an IPCablecom MTA.
+
+NOTE – The structure and content of this Recommendation have been organized for ease of use by those familiar with the original source material; as such, the usual style of ITU-T Recommendations has not been applied.
+
+# 2 References
+
+## 2.1 Normative 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.
+
+- [BB] ITU-T Recommendation J.199 (2006), *Battery backup for cable-based devices*.
+- [BPI+] ITU-T Recommendation J.125 (2004), *Link privacy for cable modem implementations*.
+- [DOCSIS0-OSSI] ANSI/SCTE 22-3 2002, *Data-Over-Cable Service Interface Specification DOCSIS 1.0 Part 3: Operations Support System Interface (OSSI)*.
+- [DOCSIS0-RFI] ANSI/SCTE 22-1 2002, *Data-Over-Cable Service Interface Specification DOCSIS 1.0 Radio Frequency Interface (RFI)*.
+- [DOCSIS1-OSSI] ANSI/SCTE 23-3 2005, *DOCSIS 1.1 Part 3: Operations Support System Interface*.
+- [DOCSIS1-RFI] ITU-T Recommendation J.112 Annex B (2004), *Data-over-cable service interface specifications: Radio-frequency interface specification*.
+- [DOCSIS2-OSSI] ANSI/SCTE 79-2 2002, *DOCS 2.0 Operations Support System Interface*.
+- [DOCSIS2-RFI] ITU-T Recommendation J.122 (2007), *Second-generation transmission systems for interactive cable television services – IP cable modems*.
+- [DOCSIS3-MULPI] ITU-T Recommendation J.222.2 (2007), *Third-generation transmission systems for interactive cable television services – IP cable modems: MAC and upper layer protocols*.
+- [DOCSIS3-OSSI] ANSI/SCTE 135-4 2007, *DOCSIS 3.0 Operations Support System Interface*.
+- [DOCSIS-OSSI] Refers to [DOCSIS1-OSSI], [DOCSIS2-OSSI] and [DOCSIS3-OSSI].
+- [DOCSIS-RFI/MULPI] Refers to [DOCSIS1-RFI], [DOCSIS2-RFI] and [DOCSIS3-MULPI].
+
+- [DSG] ITU-T Recommendation J.128 (2005), *Set-top gateway specification for transmission systems for interactive cable television services.*
+- [eRouter] ITU-T Recommendation J.218 (2007), *Cable modem IPv4 and IPv6 eRouter specification.*
+- [IETF RFC 768] IETF RFC 768 (1980), *User Datagram Protocol.*
+- [IETF RFC 791] IETF RFC 791 (1981), *Internet Protocol – DARPA Internet Program – Protocol Specification.*
+- [IETF RFC 1493] IETF RFC 1493 (1993), *Definitions of Managed Objects for Bridges.*
+- [IETF RFC 2011] IETF RFC 2011 (1996), *SNMPv2 Management Information Base for the Internet Protocol using SMIv2.*
+- [IETF RFC 2131] IETF RFC 2131 (1997), *Dynamic Host Configuration Protocol.*
+- [IETF RFC 2132] IETF RFC 2132 (1997), *DHCP Options and BOOTP Vendor Extensions.*
+- [IETF RFC 2863] IETF RFC 2863 (2000), *The Interfaces Group MIB.*
+- [IETF RFC 3396] IETF RFC 3396 (2002), *Encoding Long Options in the Dynamic Host Configuration Protocol (DHCPv4).*
+- [IETF RFC 3418] IETF RFC 3418 (2002), *Management Information Base (MIB) for the Simple Network Management Protocol (SNMP).*
+- [IETF RFC 4293] IETF RFC 4293 (2006), *Management Information Base for the Internet Protocol (IP).*
+
+## 2.2 Informative references
+
+- [CableHome] CableLabs (<http://www.cablelabs.com/projects/cablehome/>).
+- [CANN-DHCP] *CableLabs DHCP Options Registry*, CL-SP-CANN-DHCP-Reg-I01-070119, January 19, 2007, Cable Television Laboratories, Inc.
+- [CCIF 2.0] *CableCARD™ Interface 2.0 Specification*, OC-SP-CCIF2.0-I09-070105, January 5, 2007, Cable Television Laboratories, Inc.
+- [CH10] ITU-T Recommendation J.191 (2004), *IP feature package to enhance cable modems.*
+- [CH11] ITU-T Recommendation J.192 (2004), *A residential gateway to support the delivery of cable data services.*
+- [DOCSIS] CableLabs (<http://www.cablemodem.com/specifications/>).
+- [HOST2.0] *OpenCable Host Device 2.0 Core Functional Requirements*, OC-SP-HOST2.0-CFR-I14-070615, June 15, 2007, Cable Television Laboratories, Inc.
+- [IETF RFC 2578] IETF RFC 2578 (1999), *Structure of Management Information Version 2 (SMIv2).*
+- [PacketCable] CableLabs (<http://www.packetcable.com/specifications/>).
+- [PC10-MTA] ITU-T Recommendation J.167 (2001), *Media terminal adapter (MTA) device provisioning requirements for the delivery of real-time services over cable television networks using cable modems.*
+- [PC10-MIB] ITU-T Recommendation J.166 (2001), *IPCablecom Management Information Base (MIB) framework.*
+
+# 3 Definitions
+
+This Recommendation defines the following terms:
+
+**3.1 CableHome:** This is a Cable Television Laboratories, Inc. ("CableLabs") specification (see <http://www.cablelabs.com/projects/cablehome/>) for the interfaces necessary to extend high-quality cable-based services to network devices within the home. The CableHome project addresses issues such as device interoperability, QoS (Quality of Service), and network management. This term is also used for a system or device that is compliant with the CableHome specifications [CH10] or [CH11].
+
+**3.2 DOCSIS:** The term for a system or device compliant with any one of the Cable Television Laboratories, Inc. ("CableLabs") series of specifications located at: <http://www.cablemodem.com/specifications/>.
+
+**3.3 CableModem base specifications:** There are currently four versions of what are in this Recommendation referred to as the CableModem Base Specifications. The original CableModem is specified in SCTE 22-1 2002: *DOCSIS 1.0 Radio Frequency Interface* and SCTE 22-3. SCTE 22-1 is J.112 (1998) with some corrections and minor additions. The second specification is J.112 with SCTE 23-3, the third specification is J.122 with SCTE 79-2, and the fourth specification is J.222.
+
+**3.4 eCM:** An eCM is an embedded Cable Modem, i.e., one that has been enhanced with the features of this Recommendation.
+
+**3.5 eDOCSIS:** eDOCSIS is a CableLabs specification that defines the interface between the eCM and an eSAFE. The international version of the specification is this Recommendation.
+
+**3.6 eDOCSIS device:** An eDOCSIS device is one that includes an eCM entity, one or more eSAFEs and supports a single software image using a CableModem secured software download mechanism.
+
+**3.7 embedded multimedia terminal adapter (eMTA):** An embedded version of an MTA.
+
+**3.8 embedded MTA device (e-MTA):** An eDOCSIS device that contains both an eMTA and an eCM.
+
+**3.9 embedded portal service element (ePS):** An IPCable2Home-compliant eSAFE that provides management and network address translation functions between the cable data network and the home network.
+
+**3.10 logical CPE interface:** A bidirectional, data-only 802.3/Ethernet MAC frame interface between eCM and an eSAFE.
+
+**3.11 multimedia terminal adapter (MTA):** An IPCablecom device that contains the interface to a physical voice device, a network interface, CODECs, and all signalling and encapsulation functions required for VoIP transport, class features signalling and QoS signalling.
+
+**3.12 embedded service/application functional entity (eSAFE):** An embedded version of a specified application, such as an IPCablecom multimedia terminal adapter (MTA), that provides a service using the CableModem IP platform, or a function or set of functions, such as the IPCable2Home Portal Service logical element, that supports the delivery of one or more services over an IP platform.
+
+**3.13 PacketCable:** PacketCable is a CableLabs specification located at: <http://www.packetcable.com/specifications/>. The PacketCable specifications are interoperable interface specifications for delivering advanced, real-time multimedia services over a two-way cable plant. Built on top of the industry's highly successful cable modem infrastructure,
+
+PacketCable networks uses Internet Protocol (IP) technology to enable a wide range of multimedia services, such as IP telephony, multimedia conferencing, interactive gaming, and general multimedia applications. This term is also applicable to a system or device that is compliant to the PacketCable specifications. The international version of PacketCable is standardized in ITU-T J-series Recommendations J.160 to J.179.
+
+**3.14 point of deployment (POD) module:** A removable conditional access module which, when inserted into certain eSTB implementations, enables delivery of digital video programming and other services. POD module functionality includes copy protection and signal demodulation. The interface between the POD module and the eSTB is specified by [CCIF 2.0].
+
+**3.15 eRouter:** DOCSIS Embedded Router. An eSAFE that is compliant with [eRouter], providing version 4 and/or version 6 Internet Protocol-formatted data forwarding, address configuration, and Domain Name services to Internet Protocol host devices connected to the cable modem in a customer's premises.
+
+**3.16 embedded set-top box (eSTB):** An eSAFE that is compliant with [DSG], providing video, audio and data services. An example OpenCable-compliant eSTB is further specified in [HOST2.0].
+
+**3.17 embedded TDM emulator adapter (eTEA):** An eSAFE that is compliant with [TEI], providing T1 and E1 Circuit transport over IP.
+
+**3.18 monolithic firmware image:** A single firmware image containing one or more code images for the entire eDOCSIS device. For eDOCSIS devices, the Monolithic Firmware Image contains both the eCM code image as well as the applicable eSAFE code image. As an example for an eDOCSIS device containing an eSTB, the Monolithic Firmware Image contains the eCM code image as well as the eSTB code image (which may also be composed of multiple eSTB code images).
+
+**3.19 network virtual terminal (NVT):** As defined in the Telnet Protocol. NVT was a bidirectional character device, representing characters as 7-bit ASCII codes, using an 8-bit field.
+
+**3.20 OpenCable host eSTB:** An eSTB device built to CableLabs OpenCable Host specifications.
+
+**3.21 embedded security eSTB:** An eSTB with integrated security functions.
+
+**3.22 secure microprocessor:** The security element in a device that supports downloadable conditional access.
+
+**3.23 set-top device:** An eDOCSIS device that contains an eSTB.
+
+**3.24 time division multiplexing (TDM):** The means by which multiple digital signals can be carried on a single transmission path by interleaving portions of each signal in time.
+
+# 4 Abbreviations and conventions
+
+## 4.1 Abbreviations
+
+This Recommendation uses the following abbreviations:
+
+|       |                                                      |
+|-------|------------------------------------------------------|
+| ASCII | American Standard Code for Information Interchange   |
+| BSOD  | Business Services over DOCSIS                        |
+| CATV  | Community Access Television, Cable Television        |
+| CM    | Cable Modem                                          |
+| CMCI  | Cable Modem to Customer Premises Equipment Interface |
+| CMTS  | Cable Modem Termination System                       |
+
+|         |                                                  |
+|---------|--------------------------------------------------|
+| CVC     | Code Verification Certificate                    |
+| DHCP    | Dynamic Host Configuration Protocol              |
+| DIX     | Digital Intel Xerox                              |
+| DNS     | Domain Name Server                               |
+| DOCSIS  | Data-Over-Cable Service Interface Specifications |
+| DSG     | DOCSIS Set-top Gateway                           |
+| eCM     | embedded Cable Modem                             |
+| eDOCSIS | embedded DOCSIS                                  |
+| eMTA    | embedded Multimedia Terminal Adapter             |
+| ePS     | embedded Portal Services Element                 |
+| eSTB    | embedded Set-Top Box                             |
+| eSAFE   | embedded Service/Application Functional Entity   |
+| eTEA    | embedded T1/E1 TDM Emulation Adapter (TEA)       |
+| FCS     | Frame Check Sequence                             |
+| FQDN    | Fully Qualified Domain Name                      |
+| IP      | Internet Protocol                                |
+| LCI     | Logical CPE Interface                            |
+| LLC     | Logical Link Control                             |
+| MAC     | Media Access Control                             |
+| MIC     | Message Integrity Check                          |
+| MTA     | Multimedia Terminal Adapter                      |
+| OCAP    | Open Cable Application Platform                  |
+| PS      | Portal Service                                   |
+| RF      | Radio Frequency                                  |
+| ROM     | Read-Only Memory                                 |
+| SAFE    | Service/Application Functional Entity            |
+| SLED    | Software Loopback for eDOCSIS                    |
+| SNMP    | Simple Network Management Protocol               |
+| SW      | Software                                         |
+| SSD     | Secure Software Download                         |
+| TDM     | Time Division Multiplexing                       |
+| TFTP    | Trivial File Transfer Protocol                   |
+| TLV     | Type/Length/Value                                |
+| UDP     | User Datagram Protocol                           |
+| UPS     | Uninterrupted Power Supply                       |
+| USB     | Universal Serial Bus                             |
+| WAN     | Wide Area Network                                |
+
+## 4.2 Conventions
+
+Throughout this Recommendation, the words that are used to define the significance of particular requirements are capitalized. These words are:
+
+- MUST** This word or the adjective "REQUIRED" means that the item is an absolute requirement of this Recommendation.
+- MUST NOT** This phrase means that the item is an absolute prohibition of this Recommendation.
+- SHOULD** This word or the adjective "RECOMMENDED" means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighed before choosing a different course.
+- SHOULD NOT** This phrase means that there may exist valid reasons in particular circumstances when the listed behaviour is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behaviour described with this label.
+- MAY** This word or the adjective "OPTIONAL" means that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product; for example, another vendor may omit the same item.
+
+# 5 Embedded cable modem
+
+The goals for this Recommendation are:
+
+- to preserve functional separation of the Cable Modem entity from eSAFEs within the eDOCSIS device, so that existing cable plant integrity, cable modem configuration, management and provisioning security are not compromised;
+- to isolate Cable Modem functionality so that compliance can be tested for the eCM component independent of eSAFEs;
+- to enable the service provider to enable or disable forwarding traffic between each eSAFE and the eCM within the eDOCSIS Device;
+- to maximize compatibility with existing back-office management/provisioning infrastructure so that new services enabled by eDOCSIS devices can be deployed rapidly;
+- to architect eDOCSIS devices in such a way as to scale to new services and applications, and to take advantage of technology innovations to achieve low cost and high functionalities.
+
+## 5.1 Device interface reference model
+
+As per Figure 5-1, an eDOCSIS device consists of an embedded cable modem (eCM) and one or more embedded service/application functional entities (eSAFEs). An eDOCSIS device may also have one or more physically exposed interfaces. In addition, only a single secured software image download is used for the entire eDOCSIS device.
+
+eSAFEs include:
+
+- ePS: embedded IPCable2Home portal services logical element [CH10].
+- eMTA: embedded IPCablecom multimedia terminal adapter [PC10-MTA] and [PC10-MIB].
+
+- eSTB: embedded set-top box: An eSAFE that is compliant with [DSG], providing video, audio and data services. An example OpenCable-compliant eSTB is further specified in [HOST2.0].
+- eTEA: embedded T1/E1 TDM Emulation Adapter (eTEA) [TEI].
+- eRouter: An eSAFE that is compliant with [eRouter], providing Internet Protocol data forwarding, address configuration, and Domain Name services.
+
+Within an eDOCSIS device, each eSAFE interfaces to the eCM via a point-to-point logical CPE interface.
+
+Figure 5-2 presents a typical IPCable2Home Home Access eDOCSIS Device reference model.
+
+Figure 5-3 presents a logical view of protocol stacks for an eCM to ePS interface.
+
+Figure 5-4 presents a typical IPCablecom E-MTA eDOCSIS Device reference model.
+
+Figure 5-5 presents a logical view of protocol stacks for an eCM to eMTA interface.
+
+Figure 5-6 presents a typical OpenCable Host 2.0 eDOCSIS Device reference model where the Host provides DSG Flow, Socket Flow and IP Flow support.
+
+NOTE 1 – The POD module may support Socket Flow or IP Flow or both, but neither is supported simultaneously by the Host.
+
+Figure 5-7 presents a logical view of protocol stacks for an OpenCable Host 2.0 eCM to eSTB to POD module interface where the Host provides DSG Flow, Socket Flow and IP Flow support.
+
+NOTE 2 – The POD module may support Socket Flow or IP Flow or both, but neither is supported simultaneously by the Host.
+
+Figure 5-8 presents a typical embedded security STB eDOCSIS device reference model.
+
+Figure 5-9 presents a logical view of protocol stacks for an eCM to eSTB interface (embedded security STB).
+
+Figure 5-10 presents a typical T1/E1 TDM emulation adapter (TEA) eDOCSIS device reference model.
+
+Figure 5-11 presents a logical view of protocol stacks for an eCM to eTEA interface (embedded TDM emulation adapter).
+
+Figure 5-12 presents a typical DOCSIS eRouter eDOCSIS device reference model.
+
+Figure 5-13 presents a logical view of protocol stacks for an eCM to IPv4 eRouter interface.
+
+Figure 5-14 presents a logical view of protocol stacks for an eCM to IPv6 eRouter interface.
+
+![Figure 5-1: eDOCSIS reference model diagram. The diagram shows an 'eDOCSIS device' containing an 'eCM' and a 'SLED'. The 'eCM' is connected to an 'RF' input and contains 'Downstream PHY', 'Upstream PHY', 'DOCSIS MAC', 'SF Classifiers', and 'MAC Bridge and Filters'. The 'MAC Bridge and Filters' are connected to 'Logical CPE interface for PS', 'Logical CPE interface for MTA', 'Logical CPE interface for eSAFEs', and 'Physical CPE interfaces'. The 'SLED' is connected to the 'eCM' and contains 'embedded Service/Application Functional Entities' which include 'ePS', 'eMTA', and 'eSAFEs'. The 'ePS' is connected to 'Home Network (Ethernet, USB, 802.11, etc.)'. The 'eMTA' is connected to 'Phone(s) (RJ11)'. The 'eSAFEs' are connected to 'Other interfaces'. The 'Physical CPE interfaces' are connected to 'Other CPEs'. A label 'J.126(07)_F5-1' is in the bottom right corner.](4801720824e4b5e2361a5564f91cfb70_img.jpg)
+
+Figure 5-1: eDOCSIS reference model diagram. The diagram shows an 'eDOCSIS device' containing an 'eCM' and a 'SLED'. The 'eCM' is connected to an 'RF' input and contains 'Downstream PHY', 'Upstream PHY', 'DOCSIS MAC', 'SF Classifiers', and 'MAC Bridge and Filters'. The 'MAC Bridge and Filters' are connected to 'Logical CPE interface for PS', 'Logical CPE interface for MTA', 'Logical CPE interface for eSAFEs', and 'Physical CPE interfaces'. The 'SLED' is connected to the 'eCM' and contains 'embedded Service/Application Functional Entities' which include 'ePS', 'eMTA', and 'eSAFEs'. The 'ePS' is connected to 'Home Network (Ethernet, USB, 802.11, etc.)'. The 'eMTA' is connected to 'Phone(s) (RJ11)'. The 'eSAFEs' are connected to 'Other interfaces'. The 'Physical CPE interfaces' are connected to 'Other CPEs'. A label 'J.126(07)\_F5-1' is in the bottom right corner.
+
+Figure 5-1 – eDOCSIS reference model
+
+![Figure 5-2: IPCable2Home home access eDOCSIS device reference model diagram. The diagram shows an 'IP Cable2Home home access device' containing an 'eCM' and an 'ePS'. The 'eCM' is connected to an 'RF' input and is connected to the 'ePS' via a dotted line. The 'ePS' is connected to a 'Home network CMCI' output. A label 'J.126(07)_F5-2' is in the bottom right corner.](4ee27dbf5ef12e7b58b0ef0937bc5a5e_img.jpg)
+
+Figure 5-2: IPCable2Home home access eDOCSIS device reference model diagram. The diagram shows an 'IP Cable2Home home access device' containing an 'eCM' and an 'ePS'. The 'eCM' is connected to an 'RF' input and is connected to the 'ePS' via a dotted line. The 'ePS' is connected to a 'Home network CMCI' output. A label 'J.126(07)\_F5-2' is in the bottom right corner.
+
+Figure 5-2 – IPCable2Home home access eDOCSIS device reference model
+
+![Protocol stack diagram for IPCable2Home home access device showing eCM and ePS layers.](33ed1f9b27c7c21c797aa928b0f06851_img.jpg)
+
+The diagram illustrates the protocol stacks for the **IP Cable2Home home access device**, divided into two main components: **eCM** (Embedded Cable Modem) and **ePS** (Embedded Packet Switch).
+
+- eCM Stack (Left):**
+  - Top layer: DHCP, TFTP, ToD, SNMP
+  - Second layer: UDP
+  - Third layer: IP, ICMP, ARP (1 private IP address)
+  - Fourth layer: MAC mgmt, 802.2 LLC
+  - Fifth layer: 802.3 framing, MAC bridge and filters
+  - Sixth layer: DOCSIS link security
+  - Seventh layer: DOCSIS MAC
+  - Eighth layer: MPEG (d/s only)
+  - Ninth layer: DOCSIS PHY
+- ePS Stack (Right):**
+  - Top layer: DHCP, TFTP, ToD, DNS, SYSLOG, SNMP, Kerb-cros
+  - Second layer: UDP
+  - Third layer: IP, ICMP, ARP (1 public/private IP address)
+  - Fourth layer: Firewall
+  - Fifth layer: MAC bridge
+- Central Component:** CAT / CAPT (0 or more Public IP addresses)
+- Right Stack (LAN side):**
+  - Top layer: DNS server, DHCP server
+  - Second layer: UDP
+  - Third layer: IP, ICMP, ARP (1 public/private address)
+  - Fourth layer: Firewall
+  - Fifth layer: MAC bridge/switch
+  - Sixth layer: Home LAN data link(s)
+  - Seventh layer: Home LAN PHY(s)
+- Interfaces:**
+  - RF:** Radio Frequency interface on the far left.
+  - Logical CPE interface:** A bidirectional arrow between the eCM's 802.3 framing layer and the ePS's MAC bridge.
+  - Home network(s):** Connection point on the far right.
+
+J.126(07)\_F5-3
+
+Protocol stack diagram for IPCable2Home home access device showing eCM and ePS layers.
+
+**Figure 5-3 – eCM-ePS protocol stacks**
+
+![Block diagram of IPCablecom E-MTA/DOCSIS CM showing eCM, eMTA, RF, RJ11(s), and CMCI interfaces.](724c7777b608e53be38b12b6fb3c43bc_img.jpg)
+
+The diagram shows the **IP Cablecom E-MTA/DOCSIS CM** block diagram. It consists of two main internal components: **eCM** and **eMTA**, connected by a dashed line.
+
+- RF:** Radio Frequency input on the left side.
+- eCM:** Embedded Cable Modem component.
+- eMTA:** Embedded Media Terminal Adapter component.
+- RJ11(s):** Output interface on the right side.
+- CMCI:** Cable Modem Control Interface, shown as a line connecting the bottom of the eCM/eMTA block to the external environment.
+
+J.126(07)\_F5-4
+
+Block diagram of IPCablecom E-MTA/DOCSIS CM showing eCM, eMTA, RF, RJ11(s), and CMCI interfaces.
+
+**Figure 5-4 – IPCablecom E-MTA (with DOCSIS CM)  
+eDOCSIS reference model**
+
+![](fa859e4e468bfb2710a94527f2c504af_img.jpg)
+
+**IP Cablecom E-MTA device**
+
+| <b>eCM</b>                            |      |     |      | <b>eMTA</b>                                 |      |                                    |                |          |                      |
+|---------------------------------------|------|-----|------|---------------------------------------------|------|------------------------------------|----------------|----------|----------------------|
+| DHCP                                  | TFTP | ToD | SNMP | NCS                                         | SNMP | DHCP, TFTP,<br>NTP, DNS,<br>SYSLOG | Kerb-<br>beros | RTP/RTCP |                      |
+| UDP                                   |      |     |      | UDP/TCP (RSVP+)                             |      |                                    |                |          | MTA0<br><br>CODEC(s) |
+| IP, ICMP, ARP<br>1 private IP address |      |     |      | IP, ICMP, ARP, IPSEC<br>1 public IP address |      |                                    |                |          |                      |
+| MAC mgmt<br>802.2 LLC                 |      |     |      | MAC/LLC                                     |      |                                    |                |          |                      |
+| 802.3 framing                         |      |     |      | MAC bridge<br>and filters                   |      |                                    |                |          | TR909                |
+| DOCSIS link<br>security               |      |     |      |                                             |      |                                    |                |          |                      |
+| DOCSIS MAC                            |      |     |      |                                             |      |                                    |                |          |                      |
+| MPEG (d/s only)                       |      |     |      |                                             |      |                                    |                |          |                      |
+| DOCSIS PHY                            |      |     |      |                                             |      |                                    |                |          |                      |
+
+Logical CPE interface
+
+RF
+
+RJ11  
+ POTS
+
+J.126(07)\_F5-5
+
+**Figure 5-5 – eCM-eMTA protocol stacks**
+
+![](0f985b39edc1d52ba3600c438bc8f0a5_img.jpg)
+
+**OpenCable Host 2.0 STB/DOCSIS CM**
+
+RF
+
+eCM
+eSTB
+
+A/V
+
+J.126(07)\_F5-6
+
+CableCard
+
+**Figure 5-6 – OpenCable Host 2.0 eDOCSIS reference model**
+
+![Figure 5-7: eCM-eSTB protocol stacks – OpenCable Host 2.0 – Unicast IP flow. This diagram shows the protocol stacks for an eCM (Embedded Cable Modem) and a Host/eSTB (Embedded STB). The eCM stack includes layers for Prov/Mgmt Apps, UDP, IP, ICMP, ARP (1 address only), 802.2 LLC, 802.3 Framing, MAC bridge and filters, DOCSIS Link Security, DOCSIS MAC with DSG Support, MPEG (d/s only), and DOCSIS PHY. The Host/eSTB stack includes Prov/Mgmt Apps, OCAP Apps, Card IP Sockets Flow Support, TCP/UDP, IP, ICMP, ARP, eSTB MAC (802.2 LLC), DSG Support, CARD MAC (802.2 LLC), and CARD IP Flow Support. A MAC bridge is shown between the eCM and Host/eSTB. Below the Host/eSTB is a CHI (Cable Home Interface) block containing OpenCable CableCARD IF & Control, IP, TCP and/or UDP**, Other, and DSG Client. Arrows indicate various data flows: DSG Ex. Channel (red dashed), IP Ex. Channel (red solid), Ethernet/IP (black solid), CCIF APDUs (blue dashed), and DSG (black dashed).](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg)
+
+Figure 5-7: eCM-eSTB protocol stacks – OpenCable Host 2.0 – Unicast IP flow. This diagram shows the protocol stacks for an eCM (Embedded Cable Modem) and a Host/eSTB (Embedded STB). The eCM stack includes layers for Prov/Mgmt Apps, UDP, IP, ICMP, ARP (1 address only), 802.2 LLC, 802.3 Framing, MAC bridge and filters, DOCSIS Link Security, DOCSIS MAC with DSG Support, MPEG (d/s only), and DOCSIS PHY. The Host/eSTB stack includes Prov/Mgmt Apps, OCAP Apps, Card IP Sockets Flow Support, TCP/UDP, IP, ICMP, ARP, eSTB MAC (802.2 LLC), DSG Support, CARD MAC (802.2 LLC), and CARD IP Flow Support. A MAC bridge is shown between the eCM and Host/eSTB. Below the Host/eSTB is a CHI (Cable Home Interface) block containing OpenCable CableCARD IF & Control, IP, TCP and/or UDP\*\*, Other, and DSG Client. Arrows indicate various data flows: DSG Ex. Channel (red dashed), IP Ex. Channel (red solid), Ethernet/IP (black solid), CCIF APDUs (blue dashed), and DSG (black dashed).
+
+\* Prov/Mgmt Apps include: DHCP, TFTP, DNS, SNMP, ToD, etc., as dictated by the relevant specification.
+
+\*\* CableLabs places no requirements on the TCP/UDP layer of the CableCARD as such, the actual inclusion of the said protocols is at the discretion of the CableCARD provider.
+
+J.126(07)\_F5-7
+
+**Figure 5-7 – eCM-eSTB protocol stacks – OpenCable Host 2.0 – Unicast IP flow**
+
+![Figure 5-8: Embedded security STB eDOCSIS reference model. This diagram shows a reference model for an Embedded security STB. It features an 'Embedded security STB/DOCSIS CM' block containing an 'eCM' and an 'eSTB' with 'Embedded security'. The eCM is connected to an 'RF' input and a 'CMCI' output. The eSTB is connected to an 'A/V' output. There is a bidirectional connection between the eCM and the eSTB.](33a8f3f01dfa8bce75d23017855a13c5_img.jpg)
+
+Figure 5-8: Embedded security STB eDOCSIS reference model. This diagram shows a reference model for an Embedded security STB. It features an 'Embedded security STB/DOCSIS CM' block containing an 'eCM' and an 'eSTB' with 'Embedded security'. The eCM is connected to an 'RF' input and a 'CMCI' output. The eSTB is connected to an 'A/V' output. There is a bidirectional connection between the eCM and the eSTB.
+
+J.126(07)\_F5-8
+
+**Figure 5-8 – Embedded security STB eDOCSIS reference model**
+
+![Protocol stack diagram for Embedded security STB showing eCM and eSTB layers.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg)
+
+The diagram illustrates the protocol stacks for an Embedded security STB, divided into two main components: eCM and eSTB, connected by logical CPE interfaces.
+
+**eCM Stack (Left):**
+
+- Top layer: DHCP, TFTP, ToD, SNMP
+- Second layer: UDP
+- Third layer: IP, ICMP, ARP (1 IP address only)
+- Fourth layer: 802.2 LLC
+- Fifth layer: 802.3 framing, MAC bridge and filters
+- Sixth layer: DOCSIS link security
+- Seventh layer: DOCSIS MAC with DSG support
+- Eighth layer: MPEG (d/s only)
+- Ninth layer: DOCSIS PHY
+- Bottom: RF interface
+
+**eSTB Stack (Right):**
+
+- Top layer: DHCP/TFTP/DNS, SNMP, others, DSG
+- Second layer: UDP/TCP
+- Third layer: IP, ICMP, ARP (1 IP address only)
+- Fourth layer: 802.2 LLC
+
+**Connections:**
+
+- A dashed double-headed arrow labeled "Logical CPE interfaces" connects the MAC bridge and filters in the eCM stack to the 802.2 LLC layer in the eSTB stack.
+- The RF interface at the bottom of the eCM stack is connected to an external RF source.
+
+J.126(07)\_F5-9
+
+Protocol stack diagram for Embedded security STB showing eCM and eSTB layers.
+
+**Figure 5-9 – eCM-eSTB protocol stacks – Embedded security STB**
+
+![BSOD eTEA (with DOCSIS CM) eDOCSIS reference model diagram.](dfe556fea00682b09a59427aaf72051c_img.jpg)
+
+The diagram shows the BSoD eTEA (with DOCSIS CM) eDOCSIS reference model. It features a central block labeled "BSoD E-TEA/DOCSIS CM" containing two sub-components: "eCM" and "TEA".
+
+- The "eCM" component is connected to an external "RF" interface on its left.
+- A dashed line connects the "eCM" component to the "TEA" component.
+- The "TEA" component is connected to two external "TDM interfaces" on its right.
+- A "CMCI" interface is shown at the bottom, connected to the "eCM" component.
+
+J.126(07)\_F5-10
+
+BSOD eTEA (with DOCSIS CM) eDOCSIS reference model diagram.
+
+**Figure 5-10 – BSoD eTEA (with DOCSIS CM) eDOCSIS reference model**
+
+![Figure 5-11: eCM-eTEA protocol stacks diagram. It shows two protocol stacks, eCM and eTEA, within a BSoD E-TEA device. The eCM stack includes DHCP, TFTP, ToD, SNMP, UDP, IP/ICMP/ARP with a private IP address, MAC mgmt, 802.2 LLC, 802.3 framing, MAC bridge and filters, DOCSIS link security, DOCSIS MAC, MPEG (d/s only), and DOCSIS PHY. The eTEA stack includes SNMP, DHCP/TFTP, RTP, UDP, IP/ICMP/ARP/IPSEC with a public IP address, and MAC/LLC. A 'Logical CPE interface: bridge port' connects the two stacks. The eCM stack connects to an RF interface, and the eTEA stack connects through an IWF Framer LIU and a TDM I/F to a T1/E1 interface. Reference J.126(07)_F5-11 is noted.](9c6461e1e94afae4dec455e69a2ce152_img.jpg)
+
+Figure 5-11: eCM-eTEA protocol stacks diagram. It shows two protocol stacks, eCM and eTEA, within a BSoD E-TEA device. The eCM stack includes DHCP, TFTP, ToD, SNMP, UDP, IP/ICMP/ARP with a private IP address, MAC mgmt, 802.2 LLC, 802.3 framing, MAC bridge and filters, DOCSIS link security, DOCSIS MAC, MPEG (d/s only), and DOCSIS PHY. The eTEA stack includes SNMP, DHCP/TFTP, RTP, UDP, IP/ICMP/ARP/IPSEC with a public IP address, and MAC/LLC. A 'Logical CPE interface: bridge port' connects the two stacks. The eCM stack connects to an RF interface, and the eTEA stack connects through an IWF Framer LIU and a TDM I/F to a T1/E1 interface. Reference J.126(07)\_F5-11 is noted.
+
+Figure 5-11 – eCM-eTEA protocol stacks
+
+![Figure 5-12: DOCSIS eRouter eDOCSIS device reference model diagram. It shows a DOCSIS eRouter device containing an eCM and an eRouter connected by a dotted line. The eCM is connected to an RF interface on the left, and the eRouter is connected to a Home network CMCI on the right. Reference J.126(07)_F5-12 is noted.](2b3a967f6ce4f23649be995a353e39f8_img.jpg)
+
+Figure 5-12: DOCSIS eRouter eDOCSIS device reference model diagram. It shows a DOCSIS eRouter device containing an eCM and an eRouter connected by a dotted line. The eCM is connected to an RF interface on the left, and the eRouter is connected to a Home network CMCI on the right. Reference J.126(07)\_F5-12 is noted.
+
+Figure 5-12 – DOCSIS eRouter eDOCSIS device reference model
+
+![Figure 5-13: DOCSIS IPv4 eRouter eDOCSIS device reference model. This diagram shows the internal architecture of a DOCSIS eRouter eDOCSIS device. On the left, the eCM (Embedded Cable Modem) stack includes layers for DHCP, TFTP, ToD, and SNMP; UDP; IP, ICMP, and ARP with one private IP address; MAC Management and 802.2 LLC; 802.3 framing; MAC bridge and filters; DOCSIS link security; MPEG (downstream only); and DOCSIS PHY. The eCM connects via an RF interface. The central part is the IPv4 eRouter, which contains a DHCPv4 client, SNMP, and DNS components at the top. Below these are UDP and ICMPv4 layers. The IPv4 layer includes one IP address, a NAPT (Network Address Translation) component for 0 or 1 public IP address, and another IPv4 layer with one private IP address. ARP is shown on both sides of the NAPT. The IPv4 eRouter connects to a central MAC bridge via an Operator-facing interface. The MAC bridge connects to a MAC bridge/switch via a Customer-facing interface. The MAC bridge/switch is connected to Home LAN data link(s) and Home LAN data PHY(s), which in turn connect to Home network(s). The IPv4 eRouter also includes a DHCPv4 server and a Customer-facing management interface.](b6671cfafda3820aafe9a24fa7a4d8c7_img.jpg)
+
+Figure 5-13: DOCSIS IPv4 eRouter eDOCSIS device reference model. This diagram shows the internal architecture of a DOCSIS eRouter eDOCSIS device. On the left, the eCM (Embedded Cable Modem) stack includes layers for DHCP, TFTP, ToD, and SNMP; UDP; IP, ICMP, and ARP with one private IP address; MAC Management and 802.2 LLC; 802.3 framing; MAC bridge and filters; DOCSIS link security; MPEG (downstream only); and DOCSIS PHY. The eCM connects via an RF interface. The central part is the IPv4 eRouter, which contains a DHCPv4 client, SNMP, and DNS components at the top. Below these are UDP and ICMPv4 layers. The IPv4 layer includes one IP address, a NAPT (Network Address Translation) component for 0 or 1 public IP address, and another IPv4 layer with one private IP address. ARP is shown on both sides of the NAPT. The IPv4 eRouter connects to a central MAC bridge via an Operator-facing interface. The MAC bridge connects to a MAC bridge/switch via a Customer-facing interface. The MAC bridge/switch is connected to Home LAN data link(s) and Home LAN data PHY(s), which in turn connect to Home network(s). The IPv4 eRouter also includes a DHCPv4 server and a Customer-facing management interface.
+
+Figure 5-13 – DOCSIS IPv4 eRouter eDOCSIS device reference model
+
+![Figure 5-14: DOCSIS IPv6 eRouter eDOCSIS device reference model. This diagram shows the internal architecture of a DOCSIS eRouter eDOCSIS device for IPv6. The eCM stack on the left is identical to the IPv4 model. The central part is the IPv6 eRouter, which contains DHCPv6 client, SNMP, IGMPv3, and DNS components at the top. Below these are UDP, ND (Neighbor Discovery), DAD (Duplicate Address Detection), and ICMPv6 layers. The IPv6 layer includes one IP address, an IPv6 router component, and another IPv6 layer with one IP address. The IPv6 eRouter connects to a central MAC bridge via an Operator-facing interface. The MAC bridge connects to a MAC bridge/switch via a Customer-facing interface. The MAC bridge/switch is connected to Home LAN data link(s) and Home LAN data PHY(s), which in turn connect to Home network(s). The IPv6 eRouter also includes a DHCPv6 server and a Customer-facing management interface.](5445597cceefaca1ac89e710fe339325_img.jpg)
+
+Figure 5-14: DOCSIS IPv6 eRouter eDOCSIS device reference model. This diagram shows the internal architecture of a DOCSIS eRouter eDOCSIS device for IPv6. The eCM stack on the left is identical to the IPv4 model. The central part is the IPv6 eRouter, which contains DHCPv6 client, SNMP, IGMPv3, and DNS components at the top. Below these are UDP, ND (Neighbor Discovery), DAD (Duplicate Address Detection), and ICMPv6 layers. The IPv6 layer includes one IP address, an IPv6 router component, and another IPv6 layer with one IP address. The IPv6 eRouter connects to a central MAC bridge via an Operator-facing interface. The MAC bridge connects to a MAC bridge/switch via a Customer-facing interface. The MAC bridge/switch is connected to Home LAN data link(s) and Home LAN data PHY(s), which in turn connect to Home network(s). The IPv6 eRouter also includes a DHCPv6 server and a Customer-facing management interface.
+
+Figure 5-14 – DOCSIS IPv6 eRouter eDOCSIS device reference model
+
+## 5.2 eDOCSIS requirements
+
+### 5.2.1 General requirements
+
+The eCM will provide an SNMP agent which is logically separated from any SNMP agent provided by an eSAFE.
+
+Except for MIB objects that are explicitly allowed to be shared, the CableModem-specified MIBs MUST only be accessible through the Management IP address of the eCM. The eSAFE-specified MIBs MUST NOT be accessible through the Management IP address of the eCM.
+
+The MIB objects that MAY be shared are:
+
+- An eDOCSIS device MAY share MIB objects from [IETF RFC 3418]. As an exception, the eDOCSIS device MUST share the sysDescr MIB object<sup>1</sup> and report its value as defined in DOCSIS OSS.
+- An eDOCSIS device MAY share MIB objects from UDP-MIB and IP-MIB. However, the eDOCSIS device MUST not share MIB objects from IP-MIB that define per-interface management information (e.g., ipNetToMediaTable or IpNetToPhysicalTable; see clause 5.2.3.2).
+- An eDOCSIS device MAY share MIB objects rooted under snmpV2 [IETF RFC 2578].
+
+The eCM MUST act as an entity distinct from, and MUST have logical CPE interfaces to, the eSAFEs.
+
+All messages coming from the DOCSIS data network (labelled RF in the diagrams) destined for eSAFEs MUST be processed through the eCM first.
+
+The eCM MUST be the only interface to the DOCSIS data network.
+
+In addition, only a single secured software image download MUST be used for the entire eDOCSIS device and it MUST be controlled by the eCM.
+
+For an eDOCSIS device containing an eSTB, the eCM MUST implement DSG client support functionality including one-way DOCSIS and DCD MAC message as specified in DSG.
+
+An eDOCSIS device MUST NOT implement both an ePS and an eRouter simultaneously.
+
+An eCM MUST meet the requirements of an equivalent stand-alone cable modem as specified in the applicable CableModem Base Specifications. In case any requirement in this Recommendation conflicts with a requirement in the CableModem Base Specifications, the requirement in this Recommendation takes precedence for any eDOCSIS device.
+
+### 5.2.2 Interface requirements
+
+The bridging function between RF port and the CPE interfaces (logical or physical) MUST be equivalent to that of a multi-port learning bridge. Each CPE interface MUST comply with the CM Forwarding Rules defined in [DOCSIS-RFI]. In particular:
+
+- MAC addresses of each eSAFE MUST be counted toward the total allowed by the Maximum Number of CPEs configuration setting.
+
+Note that an OpenCable Host STB, where the POD module opens an IP Flow, will have at least 2 MAC addresses, one for the eSTB and one for the POD module. In this case, both MAC Addresses are counted toward the total allowed by the Maximum Number of CPEs configuration setting.
+
+- The DSG tunnel MAC addresses associated with ifIndex=18 MUST NOT be counted in the MaxCPE count of the eCM configuration file.
+- Packet forwarding and filtering rules defined in [DOCSIS-RFI] specification MUST apply to both logical and physical interfaces to eSAFE as defined in this Recommendation and in [DOCSIS-OSSI].
+
+---
+
+<sup>1</sup> In order to associate one unique image to an eDOCSIS device, the sysDescr MIB value is shared among eCM and eSAFEs. This is defined with the purpose of providing a mechanism to properly associate a firmware image with the eDevice vendor name and hardware model.
+
+- Data forwarding through the interfaces to all eSAFEs with the exception of the interface to the DSG Client (ifIndex 18) MUST obey the Network Access Control Object as defined in [DOCSIS-RFI]. NACO state does not affect the forwarding of DSG traffic (through ifIndex 18) in an eDOCSIS device containing an eSTB.
+
+### 5.2.3 Operations support requirements
+
+#### 5.2.3.1 ifTable requirements
+
+The eCM MUST represent the logical interface to each eSAFE with an entry in the ifTable with ifType other(1) as described in [DOCSIS-OSSI] and as detailed below.
+
+If the eCM is embedded into a device which contains an active (i.e., not disabled) ePS, or an eRouter, then:
+
+- the eCM MUST use ifIndex 1 (the Primary CPE interface) to represent the logical interface between the eCM and the ePS or between the eCM and the eRouter;
+- the eCM MUST NOT report in the ifTable the physically exposed interfaces associated with the ePS or with the eRouter;
+- the eCM MUST NOT report the MIB Module extensions associated with ePS or eRouter interfaces exposed to customer premises (e.g., EtherLike-MIB and USB-MIB).
+
+If the eCM is embedded into a device that contains an eRouter that is disabled, the eCM MUST report in the eCM's ifTable the physical CPE interfaces that would be associated with the eRouter if the eRouter was not disabled.
+
+NOTE – The ifIndex range allowed for CPE interfaces is described in Table 5-1.
+
+If the eCM is embedded into a device which contains an eMTA, then:
+
+- the eCM MUST use ifIndex 16 to represent the logical interface between the eCM and the eMTA;
+- the eCM MUST NOT report in the ifTable the MTA endpoints (ifType = 198).
+
+If the CM is embedded into a device which contains an eSTB, then:
+
+- The eCM MUST use ifIndex 17 to represent the logical interface between the eCM and the eSTB for the interactive IP traffic.
+- The eCM MUST use ifIndex 18 to represent the logical interface between the eCM and the eSTB for the one-way DSG tunnel traffic.
+- The eCM MUST NOT report in the ifTable any other interfaces on the eSTB (such as POD module, DSG Clients, and A/V interfaces, etc.) which are not directly and physically connected to the eCM.
+
+If the eCM is embedded into a device which contains an eTEA, then:
+
+- The eCM MUST use ifIndex 19 to represent the logical interface between the eCM and the eTEA.
+- The eCM MUST NOT report in the ifTable the eTEA interfaces (ifType = ds1(18), ds0Bundle(82), etc.).
+
+The ifXTable MUST be supported in accordance with [IETF RFC 2863]. The default value of ifLinkUpDownTrapEnable MUST be enabled(1) for logical interfaces to eSAFEs.
+
+The ifStackTable MUST be supported in accordance with [IETF RFC 2863]. The logical interface to an eSAFE MUST NOT contain any sub-layers.
+
+Table 5-1 summarizes the eCM assignment of ifIndexes to its connected interfaces. Table 5-2 defines the details of the ifTable entries that MUST be supported by ePS, eRouter, eMTA, eSTB, and eTEA.
+
+**Table 5-1 – eDOCSIS ifTable interface designations**
+
+| Interface | Type                                                                                                                |
+|-----------|---------------------------------------------------------------------------------------------------------------------|
+| 1         | Primary CPE interface (IPCable2Home ePS WAN interface or eRouter Operator-Facing Interface, when eRouter is enable) |
+| 2         | CATV-MAC                                                                                                            |
+| 3         | RF-downstream channel                                                                                               |
+| 4         | RF-upstream channel                                                                                                 |
+| 5-15      | Other CPE interfaces                                                                                                |
+| 16        | Reserved for IPCablecom/eMTA                                                                                        |
+| 17        | Reserved for eSTB-IP                                                                                                |
+| 18        | Reserved for eSTB-DSG                                                                                               |
+| 19        | Reserved for eTEA                                                                                                   |
+| 20-31     | Reserved for other eDOCSIS interfaces                                                                               |
+
+An eDOCSIS compliant eCM can have zero, one or multiple CPE interfaces, as well as interfaces to one or multiple eSAFEs. When multiple CPE interfaces are present, if filter(s) (IP, LLC, or NmAccess) are applied to the eCM's "Primary CPE Interface" (ifIndex 1), the eCM MUST also apply the same filter(s) to its "Other CPE Interfaces" (ifIndexes 5 through 15). Moreover, filters are never used to limit traffic between the CPE interfaces ("Primary CPE Interface" and "Other CPE Interfaces") within the eCM. However, if IP, LLC, or NmAccess filters are applied to the eCM's "Primary CPE Interface" (ifIndex 1), the eCM MUST NOT apply these filters to ifIndex 16 through 31, which are reserved as interfaces to eSAFEs.
+
+The above defined mechanism provides granular, independent control of filters applied to the CPE interfaces versus those applied to the interface to each eSAFE. In addition, the eCM MUST have the ability to filter traffic at a particular interface to an eSAFE, regardless of the origination point of that traffic. This granular filter control provides the ability for the eCM to filter traffic sourced by one eSAFE that is destined to another eSAFE within the same device.
+
+**Table 5-2 – [IETF RFC 2863] ifTable, MIB-Object details for eDOCSIS device interfaces**
+
+| RFC 2863 MIB-Object details for eCM-eSAFE Interfaces                                            | ePS or eRouter                                                                              | eMTA                             | eSTB                                |                                      | eTEA                          |
+|-------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------|----------------------------------|-------------------------------------|--------------------------------------|-------------------------------|
+|                                                                                                 |                                                                                             |                                  | eSTB-IP                             | eSTB-DSG                             |                               |
+| ifIndex                                                                                         | 1                                                                                           | 16                               | 17                                  | 18                                   | 19                            |
+| ifDescr: MUST match the text                                                                    | "CableHome Embedded Interface" for the ePS, or "eRouter Embedded Interface" for the eRouter | "PacketCable Embedded Interface" | "Set-Top Box Embedded IP Interface" | "Set-Top Box Embedded DSG Interface" | "BSOD Embedded TEA Interface" |
+| ifType                                                                                          | other(1)                                                                                    | other(1)                         | other (1)                           | other (1)                            | other(1)                      |
+| ifMtu                                                                                           | 0                                                                                           | 0                                | 0                                   | 0                                    | 0                             |
+| ifSpeed                                                                                         | 0                                                                                           | 0                                | 0                                   | 0                                    | 0                             |
+| ifPhysAddress                                                                                   | <empty-string>                                                                              | <empty-string>                   | <empty-string>                      | <empty-string>                       | <empty-string>                |
+| ifAdminStatus: Only up/down controls are required for this interface. Other values are optional | up(1), down(2)                                                                              | up(1), down(2)                   | up(1), down(2)                      | up(1), down(2)                       | up(1), down(2)                |
+| ifOperStatus: Only up/down controls are required for this interface. Other values are optional  | up(1), down(2)                                                                              | up(1), down(2)                   | up(1), down(2)                      | up(1), down(2)                       | up(1), down(2)                |
+| ifLastChange                                                                                    | <per RFC 2863>                                                                              | <per RFC 2863>                   | <per RFC 2863>                      | <per RFC 2863>                       | <per RFC 2863>                |
+| ifInOctets                                                                                      | (n)                                                                                         | (n)                              | (n)                                 | Deprecated                           | (n)                           |
+| ifInUCastPkts                                                                                   | (n)                                                                                         | (n)                              | (n)                                 | Deprecated                           | (n)                           |
+| ifInNUCastPkts                                                                                  | Deprecated                                                                                  | Deprecated                       | Deprecated                          | Deprecated                           | Deprecated                    |
+| ifInDiscards                                                                                    | 0                                                                                           | 0                                | 0                                   | 0                                    | 0                             |
+| ifInErrors                                                                                      | 0                                                                                           | 0                                | 0                                   | 0                                    | 0                             |
+| ifUnknownProtos                                                                                 | 0                                                                                           | 0                                | 0                                   | 0                                    | 0                             |
+| ifOutOctets                                                                                     | (n)                                                                                         | (n)                              | (n)                                 | (n)                                  | (n)                           |
+| ifOutUCastPkts                                                                                  | (n)                                                                                         | (n)                              | (n)                                 | (n)                                  | (n)                           |
+| ifOutNUCastPkts                                                                                 | Deprecated                                                                                  | Deprecated                       | Deprecated                          | Deprecated                           | Deprecated                    |
+| ifOutDiscards                                                                                   | 0                                                                                           | 0                                | 0                                   | 0                                    | 0                             |
+| ifOutErrors                                                                                     | 0                                                                                           | 0                                | 0                                   | 0                                    | 0                             |
+| ifOutQlen                                                                                       | Deprecated                                                                                  | Deprecated                       | Deprecated                          | Deprecated                           | Deprecated                    |
+| ifSpecific                                                                                      | Deprecated                                                                                  | Deprecated                       | Deprecated                          | Deprecated                           | Deprecated                    |
+
+#### 5.2.3.2 ipNetToMediaTable requirements
+
+Table 5-3 shows the details of the ipNetToMediaTable entries that MUST be supported by an ePS and eMTA.
+
+**Table 5-3 – [IETF RFC 2011] ipNetToMedia MIB-Object details for eDOCSIS device interfaces**
+
+| <b>RFC 2011 MIB-Object details for eCM-eSAFE interfaces</b> | <b>ePS</b>                                      | <b>eMTA</b>                                 | <b>eSTB-IP</b>                                 | <b>eTEA</b>                                    |
+|-------------------------------------------------------------|-------------------------------------------------|---------------------------------------------|------------------------------------------------|------------------------------------------------|
+| ipNetToMediaIfIndex                                         | 1                                               | 16                                          | 17                                             | 19                                             |
+| ipNetToMediaPhysAddress                                     | WAN-Man MAC Address                             | MTA MAC Address                             | STB MAC Address                                | TEA MAC Address                                |
+| ipNetToMediaNetAddress                                      | WAN-Man Address, if acquired; otherwise 0.0.0.0 | MTA Address, if acquired; otherwise 0.0.0.0 | STB IP Address, if acquired; otherwise 0.0.0.0 | TEA IP Address, if acquired; otherwise 0.0.0.0 |
+| ipNetToMediaType                                            | static(4)                                       | static(4)                                   | static(4)                                      | static(4)                                      |
+
+If implemented in an eDOCSIS device, eSAFE elements ePS, eMTA, eSTB, and/or eTEA SHOULD support the ipNetToPhysicalTable [IETF RFC 4293] as described in Table 5-4. The eRouter MUST support the ipNetToPhysicalTable [IETF RFC 4293] as described in Table 5-4.
+
+**Table 5-4 – ipNetToPhysical MIB-Object details for eDOCSIS device interfaces**
+
+| <b>MIB Object Name</b>        | <b>ePS or eRouter</b>                                                                                                        | <b>eMTA</b>                                                 | <b>eSTB-IP</b>                                              | <b>eTEA</b>                                                 |
+|-------------------------------|------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------|-------------------------------------------------------------|-------------------------------------------------------------|
+| ipNetToPhysicalIfIndex        | 1                                                                                                                            | 16                                                          | 17                                                          | 19                                                          |
+| ipNetToPhysicalPhysAddress    | WAN-Man MAC Address for the ePS or operator-facing interface MAC Address for the eRouter                                     | MTA MAC Address                                             | STB MAC Address                                             | TEA MAC Address                                             |
+| ipNetToPhysicalNetAddressType | ipv4(1) or ipv6(2), as applicable                                                                                            | ipv4(1) or ipv6(2), as applicable                           | ipv4(1) or ipv6(2), as applicable                           | ipv4(1) or ipv6(2), as applicable                           |
+| ipNetToPhysicalNetAddress     | WAN-Man IP Address for the ePS, or eRouter operator-facing interface IP address, if acquired; otherwise a zero-length string | MTA IP Address, if acquired; otherwise a zero-length string | STB IP Address, if acquired; otherwise a zero-length string | TEA IP Address, if acquired; otherwise a zero-length string |
+| ipNetToPhysicalLastUpdated    | <refer to RFC 4293>                                                                                                          | <refer to RFC 4293>                                         | <refer to RFC 4293>                                         | <refer to RFC 4293>                                         |
+| ipNetToPhysicalType           | static(4)                                                                                                                    | static(4)                                                   | static(4)                                                   | static(4)                                                   |
+| ipNetToPhysicalState          | <refer to RFC 4293>                                                                                                          | <refer to RFC 4293>                                         | <refer to RFC 4293>                                         | <refer to RFC 4293>                                         |
+| ipNetToPhysicalRowStatus      | 'active'                                                                                                                     | 'active'                                                    | 'active'                                                    | 'active'                                                    |
+
+#### 5.2.3.3 IETF RFC 1493 requirements
+
+The eCM MUST add ports associated with eSAFEs to its [IETF RFC 1493] dot1dBasePortTable.
+
+The eCM MUST support all bridge statistics of the [IETF RFC 1493] dot1dTpPortTable for all ports associated with eSAFEs.
+
+The eCM MUST create a row entry in its dot1dTpFdbTable for each active eSAFE MAC address within the eDOCSIS device. Note that an eSAFE could have more than one active MAC address. In the case of an eCM embedded into a device that contains an OpenCable Host, both the Host and the POD module could have active MAC addresses.
+
+Within each dot1dTpFdbTable entry for an eSAFE, the dot1dTpFdbAddress value MUST be the corresponding eSAFE MAC address, the dot1dTpFdbPort value MUST be the port associated with the ifIndex of that eSAFE from the dot1dBasePortTable, and the dot1dTpFdbStatus value MUST be mgmt(5). The eCM MUST prevent row entries for eSAFEs from being aged-out or overwritten.
+
+##### 5.2.3.3.1 IETF RFC 1493 requirements for the eSTB
+
+An eDOCSIS device containing an eSTB MUST implement the objects from the [IETF RFC 1493] dot1dStaticTable with a MAX-ACCESS of read-only.
+
+In an eDOCSIS device containing an eSTB, the eCM will acquire the DSG MAC addresses from the eSTB in an implementation-dependent manner. For each DSG MAC address acquired by the eCM, the eCM MUST create a corresponding row entry in the dot1dStaticTable.
+
+For a dot1dStaticTable row entry for a DSG MAC address, the dot1dStaticAddress value MUST be the DSG MAC address, the dot1dStaticReceivePort value MUST be the port associated with ifIndex 2 (CATV-MAC interface) from the dot1dBasePortTable, the dot1dStaticAllowedToGoTo value MUST be the port associated with the ifIndex 18 (interface to the DSG Client of the eSTB) from the dot1dBasePortTable, and the dot1dStaticStatus value MUST be deleteOnReset(4).
+
+**Table 5-5 – dot1dStaticTable entries for DSG MAC addresses**
+
+| MIB object               | Value                                                 |
+|--------------------------|-------------------------------------------------------|
+| dot1dStaticAddress       | DSG MAC Address                                       |
+| dot1dStaticReceivePort   | port associated with ifIndex 2 in dot1dBasePortTable  |
+| dot1dStaticAllowedToGoTo | port associated with ifIndex 18 in dot1dBasePortTable |
+| dot1dStaticStatus        | deleteOnReset(4)                                      |
+
+Each row entry in the dot1dStaticTable describes a bridging rule in which the eCM only bridges a frame with a destination address of the value of dot1dStaticAddress – that is received from the port represented by the value of dot1dStaticReceivePort – if the frame is to be bridged out a port included in the value of dot1dStaticAllowedToGoTo.
+
+An eCM MUST NOT bridge a frame having a destination address equal to an active DSG MAC address if that frame was received from any port other than the one associated with ifIndex 2 (CATV-MAC).
+
+An eCM MUST NOT bridge a frame having a destination address equal to an active DSG MAC address to any port other than the one associated with ifIndex 18 (the interface to the DSG Client of the eSTB).
+
+If a CPE MAC address is acquired by the eCM via the eCM Configuration File or via the address learning process, and the eCM is later informed that the same address is a DSG tunnel MAC address, the eCM SHOULD remove the DSG tunnel MAC address from its list of acquired CPE MAC addresses.
+
+Also, the eCM SHOULD NOT populate a CPE MAC address from the eCM Configuration File into its list of acquired CPE MAC addresses if that MAC address matches that of a DSG tunnel MAC address already established via DSG operation.
+
+##### 5.2.3.3.2 IETF RFC 1493 requirements for the eTEA
+
+An eCM MUST NOT bridge a frame having a destination address equal to an active eTEA MAC address if that frame was received from any port other than the one associated with ifIndex 19.
+
+An eCM MUST NOT bridge a frame having a destination address equal to an active eTEA MAC address to any port other than the one associated with ifIndex 19 (the interface to the eTEA).
+
+If a CPE MAC address is acquired by the eCM via the eCM Configuration File or via the address learning process, and the eCM is later informed that the same address is an eTEA MAC address, the eCM SHOULD remove the eTEA MAC address from its list of acquired CPE MAC addresses.
+
+#### **5.2.3.4 Battery backup UPS MIB requirements**
+
+eSAFE specifications can require support for the Battery Backup UPS MIB, if Battery Backup is supported in the containing eDOCSIS device. For more information, please refer to the Battery Backup MIB specification [BB].
+
+For an eDOCSIS device meeting the requirements specified in [BB], the eCM MUST implement the Battery Backup UPS MIB specified in [BB].
+
+### **5.2.4 DHCP option 43 syntax requirements**
+
+In order to facilitate device provisioning, all eDOCSIS devices operating with IPv4 will use DHCP [IETF RFC 2131] Option 43 during registration process for providing vendor class identification, embedded component and vendor specific capability enumerations. Requirements in this clause apply only to cable modems operating with IPv4 and do not apply to cable modems not operating with an IPv4 protocol stack, such as a DOCSIS 3.0 or greater cable modem operating with only an IPv6 protocol stack.
+
+#### **5.2.4.1 General requirements**
+
+Each eCM DHCP DISCOVER and DHCP REQUEST MUST use option 43 and its sub-options 2 through 10 for vendor-specific information to identify embedded components as specified in Table 5-6.
+
+Similarly, each eSAFE MAY issue its own DHCP DISCOVER and DHCP REQUEST with Option 43 after eCM has been successfully registered and operational; details are specified in each eSAFE's specification.
+
+#### **5.2.4.2 DHCP option 43 syntax**
+
+DHCP option 43 provides device specific information through the use of sub-options. Sub-options 1 through 10 are specified by this Recommendation, sub-options 11-127 are reserved for future definition, and sub-options 128 and above are reserved for vendor use.
+
+The eCM MUST implement the vendor-specific information option (DHCP option 43) as specified in Table 5-6. Details of DHCP option 43 and its sub-options for eDOCSIS are further defined below. The definitions of DHCP option 43 sub-options MUST conform to requirements imposed by [IETF RFC 2132].
+
+The option begins with a type octet with the value of number 43, followed by a length octet. The length octet is followed by the number of octets of data equal to the value of the length octet. The value of the length octet does not include the two octets specifying the tag and length.
+
+DHCP option 43 in eDOCSIS is a compound option. The content of option 43 is composed of one or more sub-options. Supported DHCP option 43 sub-options in eDOCSIS is in the range 1-254. A sub-option begins with a tag octet containing the sub-option code, followed by a length octet which indicates the total number of octets of data. The value of the length octet does not include itself or the tag octet. The length octet is followed by "length" octets of sub-option data.
+
+#### **5.2.4.3 DHCP option 43 sub-option encoding**
+
+The encoding of each option 43 sub-option is defined below. See Table 5-6 for the intended purpose of each sub-option.
+
+The eCM MAY include option 43 sub-option 1 in DHCP DISCOVER and DHCP REQUEST messages. If DHCP option 43 sub-option 1 is included in these DHCP client messages, the eCM MUST encode this sub-option by the number of octets equal to the value of the length octet of this
+
+sub-option, with each octet codifying a requested sub-option. If the length octet of this sub-option is 0 (because there are no requested sub-options), this sub-option SHOULD be omitted from DHCP option 43. The eCM MUST encode each of the DHCP option 43 sub-options 2, 3, 4, 5, 6, 7, 8, 9 and 10 as a character string consisting of characters from the NVT ASCII character set, with no terminating NULL.
+
+An eCM MUST send DHCP option 43 sub-option 2 containing the character string "ECM" (without the quotation marks).
+
+An eCM MUST send DHCP option 43 sub-option 3 containing a colon-separated list of all eSAFE types in the eDOCSIS device, including at a minimum the colon-separated character string "ECM:<eSAFE>" (without the quotation marks).
+
+Defined eSAFEs are: "EPS" for IPCable2Home embedded Portal Services Element, "EMTA" for IPCablecom embedded MTA, "ESTB" for embedded set-top box, and "ETEA" for embedded TDM emulation adapter.
+
+An eCM MUST send DHCP option 43 sub-option 4 containing the device serial number as in MIB object docsDevSerialNumber.
+
+An eCM MUST send DHCP option 43 sub-option 5 containing the Hardware version number, identical to the value as reported in <Hardware version> field in MIB object sysDescr.
+
+An eCM MUST send DHCP option 43 sub-option 6 containing the Software version number, identical to the value as reported in <Software version> field in MIB object sysDescr.
+
+An eCM MUST send DHCP option 43 sub-option 7 containing the Boot ROM version number, identical to the value as reported in <Boot ROM version> field in MIB object sysDescr.
+
+An eCM MUST send DHCP option 43 sub-option 8 containing a 6-octet, hexadecimally-encoded, vendor-specific organization unique identifier (OUI) that uniquely identifies the eCM manufacturer. A vendor MAY use the same OUI as in the eCM's MAC address, and MAY use a single OUI to identify all its eDOCSIS products.
+
+An eCM MUST send DHCP option 43 sub-option 9 containing the Model number, identical to the value as reported in <Model number> field in MIB object sysDescr.
+
+An eCM MUST send DHCP option 43 sub-option 10 containing the Vendor name, identical to the value as reported in <Vendor name> field in MIB object sysDescr.
+
+If an eCM is embedded with one or more eSAFEs that utilize eCM Config File Encapsulation, the eCM MUST send DHCP option 43 sub-option 15 containing the list of eSAFEs that support this feature.
+
+If an eCM is embedded in a device containing an eSTB, the eCM MUST send DHCP option 43 sub-option 18 containing the type of video security element in the device.
+
+In eDOCSIS, DHCP option 43 sub-options 11-127 are reserved for future definition and MUST NOT be used for other purposes.
+
+In eDOCSIS, DHCP option 43 sub-options 128-254 are reserved for vendors and MAY be used by vendors.
+
+If the total number of octets in all DHCP option 43 sub-options exceeds 255 octets, the eCM MUST follow [IETF RFC 3396] to split the option into multiple smaller options.
+
+**Table 5-6 – DHCP option 43 syntax**
+
+| eCM DHCP Option 43 | Value                                                                  | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
+|--------------------|------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Sub-option 1       |                                                                        | The request sub-option vector is a list of sub-options (within option 43) to be returned to client by the server upon reply to the request. None defined.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
+| Sub-option 2       | "ECM"                                                                  | Device type of the component making the DHCP request. For DOCSIS, this is:<br>"ECM"= embedded Cable Modem (as specified by DOCSIS 1.0, 1.1, 2.0, or 3.0 Base Specifications)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
+| Sub-option 3       | "ECM: <eSAFE <sub>1</sub> :eSAFE <sub>2</sub> ... SAFE <sub>n</sub> >" | Colon-separated list of eCM and eSAFE(s) contained in the complete eDOCSIS device. First on the list MUST be "ECM" for eCM. <eSAFE <sub>x</sub> > can be "EMTA", "EPS", "EROUTER", "ESTB", or "ETEA" corresponding to embedded MTA, embedded Portal Services Element, embedded Router, embedded STB, and embedded TDM Emulation Adapter, respectively.<br>For example:<br>"ECM:EMTA" = A PacketCable/Embedded MTA<br>"ECM:EPS" = A CableHome/Embedded Portal Services Element<br>"ECM:EROUTER" = A DOCSIS Embedded Router<br>"ECM:ESTB" = An Embedded STB<br>"ECM:ETEA" = An Embedded TEA<br>"ECM:EMTA:EPS" = An Embedded MTA and Embedded Portal Services Element                                        |
+| Sub-option 4       | "<device serial number>"                                               | Device serial number as in MIB object docsDevSerialNumber<br>e.g., "123456"                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
+| Sub-option 5       | "<Hardware version>"                                                   | Hardware version number. Identical to value as reported in the <Hardware version> field in MIB object sysDescr.<br>e.g., "v.3.2.1"                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
+| Sub-option 6       | "<Software version>"                                                   | Software version number. Identical to value as reported in the <Software version> field in MIB object sysDescr.<br>e.g., "v.1.0.2"                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
+| Sub-option 7       | "<Boot ROM version>"                                                   | Boot ROM version. Identical to value as reported in the <Boot ROM version> field in MIB object sysDescr.<br>e.g., "Bv4.5.6"                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
+| Sub-option 8       | "<OUI>"                                                                | A 6-octet, hexadecimally-encoded, vendor-specific organization unique identifier (OUI) that may match the OUI in eCM's MAC address.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
+| Sub-option 9       | "<Model number>"                                                       | Device model number. Identical to value as reported in the <Model number> field in MIB object sysDescr.<br>e.g., "T3000"                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
+| Sub-option 10      | "<Vendor name>"                                                        | Vendor name or ID. Identical to value as reported in the <Vendor name> field in MIB object sysDescr.<br>e.g., "XYZ Corp"                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
+| Sub-option 15      | "<eSAFE <sub>1</sub> :eSAFE <sub>2</sub> ... SAFE <sub>n</sub> >"      | Colon-separated list of eSAFEs contained in the eDOCSIS device that supports eCM Config File Encapsulation. The list could contain "EMTA", "EPS", "ESTB", "ETEA" or "EROUTER". The requirements for support of eCM Config File Encapsulation by each eSAFE type (and hence the requirements for the contents of this sub-option) can be found in the relevant eSAFE specification.<br>If no eSAFE supports eCM Config File Encapsulation, then the eCM MUST either not populate this sub-option, or set the sub-option length to zero.<br>For example:<br>"ESTB" = An Embedded STB with eCM eSAFE config file TLV support (or absence of sub-option 15) = no eSAFE supports the eCM eSAFE config file TLV |
+
+**Table 5-6 – DHCP option 43 syntax**
+
+| <b>eCM DHCP Option 43</b> | <b>Value</b>             | <b>Description</b>                                                                                                                                                                                                                                                                                                                           |
+|---------------------------|--------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Sub-option 18             | "<VideoSecurityElement>" | Video Security Type<br>Only present if the device contains an eSTB. This sub-option takes one of the following values:<br>"CARD" corresponds to an eSTB with a POD module as its security element.<br>"SM" corresponds to an eSTB with a Secure Microprocessor as its security element.<br>"EMBED" corresponds to an embedded security eSTB. |
+
+#### **5.2.4.4 Examples (informative)**
+
+##### **5.2.4.4.1 DOCSIS cable modem with embedded IPCablecom 1.0 MTA example**
+
+Table 5-7 shows the syntax for DHCP option 43 for the eCM in an E-MTA.
+
+**Table 5-7 – Example eDOCSIS device: E-MTA**
+
+| <b>DHCP DISCOVER options</b> | <b>Value</b>                            | <b>Description</b>                                                                         |
+|------------------------------|-----------------------------------------|--------------------------------------------------------------------------------------------|
+| <b>eCM DHCP DISCOVER</b>     |                                         |                                                                                            |
+| eCM Option 43 sub-option 1   | N/A (omitted because the list is empty) | List of sub-options (within option 43) to be returned by server                            |
+| eCM Option 43 sub-option 2   | "ECM"                                   | Embedded cable modem                                                                       |
+| eCM Option 43 sub-option 3   | "ECM:EMTA"                              | ECM followed by a list of embedded components (eSAFEs)                                     |
+| eCM Option 43 sub-option 4   | "123456"                                | Device serial number as in MIB object <code>docsDevSerialNumber</code>                     |
+| eCM Option 43 sub-option 5   | "V1.2.3"                                | Hardware version number as in <Hardware version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 6   | "V3.2.1"                                | Software version number as in <Software version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 7   | "Boot 4.5.6"                            | Boot ROM version number as in <Boot ROM version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 8   | "0204DF"                                | 6-octet OUI as Vendor ID                                                                   |
+| eCM Option 43 sub-option 9   | "Xman200"                               | Device model number as in <Model number> field in MIB object <code>sysDescr</code>         |
+| eCM Option 43 sub-option 10  | "XYZ Broadband"                         | Vendor name as in <Vendor name> field in MIB object <code>sysDescr</code>                  |
+
+##### **5.2.4.4.2 DOCSIS cable modem with embedded IPCable2Home 1.1 PS example**
+
+Table 5-8 shows the syntax for DHCP options 43 for the eCM in an IPCable2Home 1.1 ePS device.
+
+**Table 5-8 – Example eDOCSIS device: DOCSIS 1.1 IPCable2Home/ePS**
+
+| DHCP DISCOVER options       | Value           | Description                                                                                |
+|-----------------------------|-----------------|--------------------------------------------------------------------------------------------|
+| <b>eCM DHCP DISCOVER</b>    |                 |                                                                                            |
+| eCM Option 43 sub-option 1  | "<null>"        | List of sub-options (within option 43) to be returned by server                            |
+| eCM Option 43 sub-option 2  | "ECM"           | Embedded cable modem                                                                       |
+| eCM Option 43 sub-option 3  | "ECM:EPS"       | ECM followed by a list of embedded components (eSAFEs)                                     |
+| eCM Option 43 sub-option 4  | "123456"        | Device serial number as in MIB object <code>docsDevSerialNumber</code>                     |
+| eCM Option 43 sub-option 5  | "V1.2.3"        | Hardware version number as in <Hardware version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 6  | "V3.2.1"        | Software version number as in <Software version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 7  | "Boot 4.5.6"    | Boot ROM version number as in <Boot ROM version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 8  | "0204DF"        | 6-octet OUI as Vendor ID                                                                   |
+| eCM Option 43 sub-option 9  | "Xman200"       | Device model number as in <Model number> field in MIB object <code>sysDescr</code>         |
+| eCM Option 43 sub-option 10 | "XYZ Broadband" | Vendor name as in <Vendor name> field in MIB object <code>sysDescr</code>                  |
+
+##### 5.2.4.4.3 DOCSIS cable modem with embedded STB example
+
+Table 5-9 illustrates the syntax for DHCP options 43 for the eCM with an embedded STB.
+
+**Table 5-9 – Example eDOCSIS device: DOCSIS 1.1 embedded STB**
+
+| DHCP DISCOVER & REQUEST Options        | Options Value                           | Description                                                                                                                                                           |
+|----------------------------------------|-----------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| <b>eCM DHCP DISCOVER &amp; REQUEST</b> |                                         |                                                                                                                                                                       |
+| eCM Option 43 sub-option 1             | N/A (omitted because the list is empty) | List of sub-options (within option 43) to be returned by server.                                                                                                      |
+| eCM Option 43 sub-option 2             | "ECM"                                   | Device type of the entity making the DHCP request. For DOCSIS, this is:<br>"ECM" = embedded Cable Modem (as specified by DOCSIS 1.0, 1.1, or 2.0 Base Specifications) |
+| eCM Option 43 sub-option 3             | "ECM:ESTB"                              | Colon-separated list of eCM and eSAFE(s) contained in the device. First on the list MUST be "ECM".<br>"ECM" = embedded CM<br>"ESTB" = embedded STB                    |
+| eCM Option 43 sub-option 4             | e.g., "123456"                          | Device serial number from MIB object <code>docsDevSerialNumber</code>                                                                                                 |
+| eCM Option 43 sub-option 5             | e.g., "V1.2.3"                          | Hardware version number from <Hardware version> field in MIB object <code>sysDescr</code>                                                                             |
+| eCM Option 43 sub-option 6             | e.g., "V3.2.1"                          | Software version number from <Software version> field in MIB object <code>sysDescr</code>                                                                             |
+| eCM Option 43 sub-option 7             | "Boot 4.5.6"                            | Boot ROM version number from <Boot ROM version> field in MIB object <code>sysDescr</code>                                                                             |
+| eCM Option 43 sub-option 8             | "0204DF"                                | A 6-octet, hexadecimally-encoded, vendor-specific organization unique identifier (OUI) that may match the OUI in the eCM's MAC address                                |
+
+**Table 5-9 – Example eDOCSIS device: DOCSIS 1.1 embedded STB**
+
+| DHCP DISCOVER & REQUEST Options        | Options Value   | Description                                                                       |
+|----------------------------------------|-----------------|-----------------------------------------------------------------------------------|
+| <b>eCM DHCP DISCOVER &amp; REQUEST</b> |                 |                                                                                   |
+| eCM Option 43 sub-option 9             | "Xman200"       | Device model number from <Model number> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 10            | "XYZ Broadband" | Vendor name as in <Vendor name> field in MIB object <code>sysDescr</code>         |
+| eCM Option 43 sub-option 15            | "ESTB"          | eSTB supports eCM eSAFE Config file TLVs                                          |
+| eCM Option 43 sub-option 18            | "EMBED"         | This device contains an embedded security eSTB.                                   |
+
+##### 5.2.4.4.4 DOCSIS Cable Modem with embedded IPCablecom MTA and IPCable2Home PS
+
+Table 5-10 shows the syntax for DHCP option 43 for the eCM in an eDOCSIS device that contains the following embedded components: a DOCSIS 2.0 eCM, an IPCablecom 1.0 eMTA and an IPCable2Home 1.1 ePS.
+
+**Table 5-10 – Example eDOCSIS device containing DOCSIS 2.0 eCM, eMTA and ePS**
+
+| DHCP DISCOVER options       | Value           | Description                                                                                |
+|-----------------------------|-----------------|--------------------------------------------------------------------------------------------|
+| <b>eCM DHCP DISCOVER</b>    |                 |                                                                                            |
+| eCM Option 43 sub-option 1  | "<null>"        | List of sub-options (within option 43) to be returned by server                            |
+| eCM Option 43 sub-option 2  | "ECM"           | Embedded cable modem                                                                       |
+| eCM Option 43 sub-option 3  | "ECM:EMTA:EPS"  | ECM followed by a list of embedded components (eSAFEs)                                     |
+| eCM Option 43 sub-option 4  | "123456"        | Device serial number as in MIB object <code>docsDevSerialNumber</code>                     |
+| eCM Option 43 sub-option 5  | "V1.2.3"        | Hardware version number as in <Hardware version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 6  | "V3.2.1"        | Software version number as in <Software version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 7  | "Boot 4.5.6"    | Boot ROM version number as in <Boot ROM version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 8  | "0204DF"        | 6-octet OUI as Vendor ID                                                                   |
+| eCM Option 43 sub-option 9  | "Xman200"       | Device model number as in <Model number> field in MIB object <code>sysDescr</code>         |
+| eCM Option 43 sub-option 10 | "XYZ Broadband" | Vendor name as in <Vendor name> field in MIB object <code>sysDescr</code>                  |
+
+##### 5.2.4.4.5 DOCSIS cable modem with embedded TEA
+
+Table 5-11 shows the syntax for DHCP option 43 for the eCM with an embedded TEA.
+
+**Table 5-11 – Example eDOCSIS device: DOCSIS 1.1 TEA**
+
+| DHCP DISCOVER Options       | Value                                   | Description                                                                                |
+|-----------------------------|-----------------------------------------|--------------------------------------------------------------------------------------------|
+| <b>eCM DHCP DISCOVER</b>    |                                         |                                                                                            |
+| eCM Option 43 sub-option 1  | N/A (omitted because the list is empty) | List of sub-options (within option 43) to be returned by server                            |
+| eCM Option 43 sub-option 2  | "ECM"                                   | Embedded cable modem                                                                       |
+| eCM Option 43 sub-option 3  | "ECM:ETEA"                              | ECM followed by a list of embedded components (eSAFEs)                                     |
+| eCM Option 43 sub-option 4  | "123456"                                | Device serial number as in MIB object <code>docsDevSerialNumber</code>                     |
+| eCM Option 43 sub-option 5  | "V1.2.3"                                | Hardware version number as in <Hardware version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 6  | "V3.2.1"                                | Software version number as in <Software version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 7  | "Boot 4.5.6"                            | Boot ROM version number as in <Boot ROM version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 8  | "0204DF"                                | 6-octet OUI as Vendor ID                                                                   |
+| eCM Option 43 sub-option 9  | "Xman200"                               | Device model number as in <Model number> field in MIB object <code>sysDescr</code>         |
+| eCM Option 43 sub-option 10 | "XYZ Broadband"                         | Vendor name as in <Vendor name> field in MIB object <code>sysDescr</code>                  |
+
+##### **5.2.4.4.6 DOCSIS cable modem with embedded router**
+
+Table 5-12 shows the syntax for DHCP Option 43 for the eCM with an embedded router.
+
+**Table 5-12 – DOCSIS cable modem with embedded router**
+
+| DHCP DISCOVER Options       | Value                                   | Description                                                                                |
+|-----------------------------|-----------------------------------------|--------------------------------------------------------------------------------------------|
+| <b>eCM DHCP DISCOVER</b>    |                                         |                                                                                            |
+| eCM Option 43 sub-option 1  | N/A (omitted because the list is empty) | List of sub-options (within option 43) to be returned by server                            |
+| eCM Option 43 sub-option 2  | "ECM"                                   | Embedded cable modem                                                                       |
+| eCM Option 43 sub-option 3  | "ECM:EROUTER"                           | ECM followed by a list of embedded components (eSAFEs)                                     |
+| eCM Option 43 sub-option 4  | "123456"                                | Device serial number as in MIB object <code>docsDevSerialNumber</code>                     |
+| eCM Option 43 sub-option 5  | "V1.2.3"                                | Hardware version number as in <Hardware version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 6  | "V3.2.1"                                | Software version number as in <Software version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 7  | "Boot 4.5.6"                            | Boot ROM version number as in <Boot ROM version> field in MIB object <code>sysDescr</code> |
+| eCM Option 43 sub-option 8  | "0204DF"                                | 6-octet OUI as Vendor ID                                                                   |
+| eCM Option 43 sub-option 9  | "Xman200"                               | Device model number as in <Model number> field in MIB object <code>sysDescr</code>         |
+| eCM Option 43 sub-option 10 | "XYZ Broadband"                         | Vendor name as in <Vendor name> field in MIB object <code>sysDescr</code>                  |
+| eCM Option 43 sub-option 15 | "EROUTER"                               | eRouter supports eCM eSAFE Config file TLVs                                                |
+
+### 5.2.5 DHCPv6 vendor-specific option syntax requirements
+
+In order to facilitate provisioning, all eDOCSIS devices implementing a DOCSIS 3.0 or greater CM and operating with IPv6 will include vendor-specific information options during the CM IPv6 registration process [DOCSIS3-MULPI]. Vendor-specific information options include configuration file location and name information, syslog server information, device identifier information, and cable modem capabilities. Refer to [CANN-DHCP].
+
+#### 5.2.5.1 eDOCSIS device information in DHCPv6 vendor-specific options
+
+An eCM operating with IPv6 provides device-specific information through the use of the DHCPv6 vendor-specific information options. This information, which is carried in option 43 sub-options in the case of an eCM or eSAFE using IPv4, provides the provisioning system with details about the eDOCSIS device, including implemented CableLabs specification, hardware revision, software revision, and number and type of implemented eSAFEs. Refer to clause 5.2.4.3 for more information about DHCPv4 option 43 requirements.
+
+An eCM operating with IPv6 MUST include the DHCPv6 vendor-specific option codes listed below in DHCPv6 solicit messages:
+
+- Option Code 2: Embedded Cable Modem Identifier
+- Option Code 3: List of Implemented eSAFEs
+- Option Code 4: Device Serial Number
+- Option Code 5: Hardware Version Number
+- Option Code 6: Software Version Number
+- Option Code 9: Model Number
+- Option Code 10: Vendor Identifier
+
+The format of the DHCPv6 vendor specific option codes 2-6 and 9-10 listed above generally follow the format of other vendor-specific options described in [CANN-DHCP]. The specific format of each of the required Option Codes listed above is described below.
+
+##### Option Code 2: Embedded Cable Modem Identifier
+
+Option code 2 contains the string ECM, indicating to the provisioning system that the DHCP client is implemented on an embedded cable modem.
+
+![](1841f348dfa81a3438d4e1f8465d9ac7_img.jpg)
+
+```
+
+      0                     1                     2                     3
+      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |  CL_OPTION_ECM_ID             | 3                             |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+      |  E      |  C      |  M      |
+      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+  
+```
+
+##### Option Code 3: List of Implemented eSAFEs
+
+This option is a colon-separated list of eSAFEs implemented in the eDOCSIS device. The CM MUST list in the List of Implemented eSAFEs option the abbreviation for each eSAFE implemented in the device, beginning with ECM and separated with a colon. Defined eSAFE abbreviations are listed in the Description field for DHCPv4 Option 43, sub-option 3 in Table 5-6.
+
+| 0                                  |   |   |   |   |   |   |   | 1 |   |   |   |   |   |   |   | 2          |   |   |   |   |   |   |   | 3 |   |   |   |   |   |   |   |
+|------------------------------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
+| 0                                  | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6          | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 |
+| CL_OPTION_EMBEDDED_COMPONENTS_LIST |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   | option-len |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| E                                  |   |   |   |   |   |   |   | C |   |   |   |   |   |   |   | M          |   |   |   |   |   |   |   | : |   |   |   |   |   |   |   |
+| eSAFE_1:                           |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| eSAFE_2:                           |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| eSAFE_n                            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+
+An example of the List of Implemented eSAFEs for a hypothetical product implementing an eCM, eMTA, and eSTB follows:
+
+| 0 |   |   |   |   |   |   |   | 1 |   |   |   |   |   |   |   | 2    |   |   |   |   |   |   |   | 3 |   |   |   |   |   |   |   |
+|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
+| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6    | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 |
+| 3 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   | 0x0E |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| E |   |   |   |   |   |   |   | C |   |   |   |   |   |   |   | M    |   |   |   |   |   |   |   | : |   |   |   |   |   |   |   |
+| E |   |   |   |   |   |   |   | M |   |   |   |   |   |   |   | T    |   |   |   |   |   |   |   | A |   |   |   |   |   |   |   |
+| : |   |   |   |   |   |   |   | E |   |   |   |   |   |   |   | S    |   |   |   |   |   |   |   | T |   |   |   |   |   |   |   |
+| B |   |   |   |   |   |   |   | : |   |   |   |   |   |   |   |      |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+
+### Option Code 4: Device Serial Number
+
+The Device Serial Number option contains the eDOCSIS device's serial number.
+
+| 0                              |   |   |   |   |   |   |   | 1 |   |   |   |   |   |   |   | 2          |   |   |   |   |   |   |   | 3 |   |   |   |   |   |   |   |
+|--------------------------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
+| 0                              | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6          | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 |
+| CL_OPTION_DEVICE_SERIAL_NUMBER |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   | option-len |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| Serial Number                  |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+
+### Option Code 5: Hardware Version Number
+
+The Hardware Version Number option contains the eDOCSIS device's hardware version number.
+
+| 0                                 |   |   |   |   |   |   |   | 1 |   |   |   |   |   |   |   | 2          |   |   |   |   |   |   |   | 3 |   |   |   |   |   |   |   |
+|-----------------------------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
+| 0                                 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6          | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 |
+| CL_OPTION_HARDWARE_VERSION_NUMBER |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   | option-len |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| Hardware Version Number           |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+
+ITU-T Rec. J.126 (12/2007) 29
+
+##### Option Code 6: Software Version Number
+
+The Software Version Number option contains the vendor-assigned version number of the software implemented in the device.
+
+![Diagram of Option Code 6: Software Version Number. It shows a header with CL_OPTION_SOFTWARE_VERSION_NUMBER and option-len, followed by the Software Version Number field.](1142ba0197b158bb198186fe8baccc32_img.jpg)
+
+Diagram illustrating the structure of Option Code 6: Software Version Number. The diagram shows a header with two fields: CL\_OPTION\_SOFTWARE\_VERSION\_NUMBER and option-len, followed by the Software Version Number field. The header is 4 bytes long, with the first byte containing the option code (0x06) and the remaining three bytes containing the option length. The Software Version Number field is variable in length.
+
+|                                   |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+|-----------------------------------|---|---|---|---|---|---|---|---|---|------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
+| 0                                 | 1 |   |   |   |   |   |   |   | 2 |            |   |   |   |   |   |   | 3 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| 0                                 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0          | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 |
+| CL_OPTION_SOFTWARE_VERSION_NUMBER |   |   |   |   |   |   |   |   |   | option-len |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| Software Version Number           |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| ...                               |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+
+Diagram of Option Code 6: Software Version Number. It shows a header with CL\_OPTION\_SOFTWARE\_VERSION\_NUMBER and option-len, followed by the Software Version Number field.
+
+##### Option Code 9: Device Model Number
+
+The Device Model Number option contains the model number of the eDOCSIS device.
+
+![Diagram of Option Code 9: Device Model Number. It shows a header with CL_OPTION_MODEL_NUMBER and option-len, followed by the Device Model Number field.](fcbc3c31776721edc98ceb1944ec438f_img.jpg)
+
+Diagram illustrating the structure of Option Code 9: Device Model Number. The diagram shows a header with two fields: CL\_OPTION\_MODEL\_NUMBER and option-len, followed by the Device Model Number field. The header is 4 bytes long, with the first byte containing the option code (0x09) and the remaining three bytes containing the option length. The Device Model Number field is variable in length.
+
+|                        |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+|------------------------|---|---|---|---|---|---|---|---|---|------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
+| 0                      | 1 |   |   |   |   |   |   |   | 2 |            |   |   |   |   |   |   | 3 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| 0                      | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0          | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 |
+| CL_OPTION_MODEL_NUMBER |   |   |   |   |   |   |   |   |   | option-len |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| Device Model Number    |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| ...                    |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+
+Diagram of Option Code 9: Device Model Number. It shows a header with CL\_OPTION\_MODEL\_NUMBER and option-len, followed by the Device Model Number field.
+
+##### Option Code 10: Vendor Identifier
+
+The Vendor Identifier option contains the name or other identifier of the vendor who manufactures and/or sells the eDOCSIS device.
+
+![Diagram of Option Code 10: Vendor Identifier. It shows a header with CL_OPTION_VENDOR_OUI and option-len, followed by the Vendor Identifier field.](409498e57b1f988b2b604d12cd997002_img.jpg)
+
+Diagram illustrating the structure of Option Code 10: Vendor Identifier. The diagram shows a header with two fields: CL\_OPTION\_VENDOR\_OUI and option-len, followed by the Vendor Identifier field. The header is 4 bytes long, with the first byte containing the option code (0x0A) and the remaining three bytes containing the option length. The Vendor Identifier field is variable in length.
+
+|                      |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+|----------------------|---|---|---|---|---|---|---|---|---|------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
+| 0                    | 1 |   |   |   |   |   |   |   | 2 |            |   |   |   |   |   |   | 3 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| 0                    | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0          | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 |
+| CL_OPTION_VENDOR_OUI |   |   |   |   |   |   |   |   |   | option-len |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| Vendor Identifier    |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| ...                  |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+
+Diagram of Option Code 10: Vendor Identifier. It shows a header with CL\_OPTION\_VENDOR\_OUI and option-len, followed by the Vendor Identifier field.
+
+##### Option Code 15: eCM Config File Encapsulation
+
+The eCM Config File Encapsulation option indicates the list of eSAFE devices that support this feature.
+
+![Diagram of Option Code 15: eCM Config File Encapsulation. It shows a header with CL_OPTION_ECM_CFG_ENCAPS and option-len, followed by the eCM Config File Encapsulation field.](f1cbfa3fc27f58581615654fec4335d8_img.jpg)
+
+Diagram illustrating the structure of Option Code 15: eCM Config File Encapsulation. The diagram shows a header with two fields: CL\_OPTION\_ECM\_CFG\_ENCAPS and option-len, followed by the eCM Config File Encapsulation field. The header is 4 bytes long, with the first byte containing the option code (0x0F) and the remaining three bytes containing the option length. The eCM Config File Encapsulation field is variable in length.
+
+|                               |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+|-------------------------------|---|---|---|---|---|---|---|---|---|------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
+| 0                             | 1 |   |   |   |   |   |   |   | 2 |            |   |   |   |   |   |   | 3 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| 0                             | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0          | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 |
+| CL_OPTION_ECM_CFG_ENCAPS      |   |   |   |   |   |   |   |   |   | option-len |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| eCM Config File Encapsulation |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+| ...                           |   |   |   |   |   |   |   |   |   |            |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+
+Diagram of Option Code 15: eCM Config File Encapsulation. It shows a header with CL\_OPTION\_ECM\_CFG\_ENCAPS and option-len, followed by the eCM Config File Encapsulation field.
+
+### 5.2.6 Testability requirements
+
+In order to verify conformance to this Recommendation and to the DOCSIS Base Specifications, a mechanism to generate and receive traffic bridged through the eCM is required. eDOCSIS devices that have a physically exposed CMCI (e.g., 10BaseT or USB) can be tested by using external packet generation equipment connected to that interface.
+
+For cost, security, or other reasons, however, certain eDOCSIS devices may not have an exposed CMCI, necessitating an alternative mechanism.
+
+Additionally, an eDOCSIS device MAY have multiple eSAFEs, each with a logical CPE interface (LCI) to the eCM. This Recommendation places requirements on the LCIs as well as the bridging of traffic among eCM and eSAFEs.
+
+To this end, a software loopback for eDOCSIS (SLED) is specified below.
+
+#### 5.2.6.1 General requirements
+
+An eCM SHOULD implement SLED. An eCM without an externally accessible CMCI port, or a physical interface configured to be equivalent to a CMCI port, MUST implement SLED.
+
+#### 5.2.6.2 SLED protocol description
+
+##### 5.2.6.2.1 General description
+
+SLED is an embedded test function residing in an eCM enabling DOCSIS and eDOCSIS conformance testing coverage, particularly when an exposed CMCI is not available.
+
+The SLED test functions are controlled via SLED MIB objects as specified in Annex A. The SLED MIB objects MUST be associated with the SNMP stack of the eCM. The SLED MIB objects MUST NOT be accessible through the CMCI.
+
+To prevent unintended activation of SLED, all SLED functions MUST be disabled by default. SLED functions MUST only be enabled if the MIB object *sledGlobalEnable* is set to 'true' prior to eCM registration; *sledGlobalEnable* MAY be set to 'true' via inclusion in TLV-11 of the eCM's configuration file.
+
+The SLED MIB values revert to power-on values when the CM de-registers or loses Operational state; the *sledGlobalEnable* will revert to 'false' and in-progress packet generation or loopback will be stopped.
+
+Figure 5-15 illustrates the SLED reference model.
+
+![Figure 5-15 – SLED reference model diagram](a9bd36d25444d896e8d6941ff59d8f2d_img.jpg)
+
+```
+
+graph LR
+    subgraph Test_station [Test station]
+        PS[Packet sniffer]
+        PG[Packet generator]
+    end
+
+    subgraph CMTS_Block [CMTS]
+        NSI[NSI]
+        RFI[RFI]
+        NSI --- RFI
+    end
+
+    subgraph eDOCSIS_device [eDOCSIS device]
+        subgraph eCM [eCM]
+            MIB[(SLED MIB)]
+        end
+        LCI[LCI]
+        eSAFE[eSAFE]
+        subgraph SLED_Block [SLED]
+            Loopback[Loopback]
+            PacketGen[Packet Gen]
+        end
+    end
+
+    PG --> NSI
+    NSI --> PS
+    RFI <--> eCM
+    eCM <--> LCI
+    LCI <--> eSAFE
+    eCM --> Loopback
+    Loopback --> eCM
+    PacketGen --> eSAFE
+
+```
+
+The diagram illustrates the SLED reference model. A 'Test station' containing a 'Packet sniffer' and 'Packet generator' connects via an 'NSI' to a 'CMTS'. The 'CMTS' connects via an 'RFI' to an 'eDOCSIS device'. Inside the 'eDOCSIS device', an 'eCM' (containing a 'SLED MIB') connects to an 'eSAFE' via an 'LCI'. A 'SLED' functional block within the device contains 'Loopback' (interfacing with the 'eCM') and 'Packet Gen' (interfacing with the 'eSAFE'). Bidirectional arrows indicate traffic flow between the CMTS and the eCM, and between the eCM, LCI, and eSAFE.
+
+Figure 5-15 – SLED reference model diagram
+
+Figure 5-15 – SLED reference model
+
+The SLED functionality supports:
+
+###### 1) *Packet loopback*
+
+The primary purpose of the Packet loopback protocol is to enable verification of the receipt of packets across the LCI by the eSAFE. Once enabled by the SLED MIB object, all packets that are forwarded to the indicated LCI are encapsulated into a predefined packet header (Ethernet DIX frame header + IP header + UDP header) and reflected back across the LCI to the eCM for forwarding to the final destination. Typically, the looped-back packets will be addressed to, and captured by, a test station residing in the network side interface (NSI) of the CMTS.
+
+###### 2) *Packet generation*
+
+SLED MIB objects are defined to enable setting up of Ethernet framing and payload transmission for packet generation and transmission through the LCI to the eCM. The SLED MIB objects described below control the packet transmission with parameters such as Ethernet packet header, packet rate, and the number of packets.
+
+3) Packet loopback and packet generation SLED functions MUST be able to be controlled independently.
+
+4) The packet loopback and packet generation SLED functions MUST NOT disrupt network connectivity to or from the eSAFE. When SLED loopback is enabled, a packet transmitted across the LCI in the eCM-to-eSAFE direction, MUST be forwarded to both the eSAFE and the SLED loopback function. When SLED functions are enabled, packets to/from the eSAFE MUST continue to be bridged across the LCI.
+
+##### 5.2.6.2.2 Loopback protocol
+
+An eCM implementing SLED MUST implement the following loopback protocol:
+
+1) The SLED packet loopback function is attached to the LCI associated with the eSAFE by setting SLED MIB *sledLoopbackInterface* to the eCM's ifIndex number associated with the LCI (per Table 5-1).
+
+2) The SLED MIB object *sledLoopbackPktHdr* is configured with the 42-byte loopback Ethernet packet/IP/UDP headers (14-byte Ethernet header + 20-byte IPv4 header + 8-byte UDP header).
+
+3) As an example, the following loopback header parameters could be used:
+
+- a) Ethernet MAC source address = eSAFE MAC address;
+- b) Ethernet MAC destination address = test station MAC address;
+- c) IP source address = eSAFE Management IP address;
+- d) IP destination address = test station IP address;
+- e) UDP source port number = 7;
+- f) UDP destination port number = 7.
+
+4) When the SLED MIB object *sledLoopbackInterface* is set to an ifIndex associated with an LCI which supports SLED, *sledLoopbackPktHdr* contains a 42-byte octet string, and *sledLoopbackEnable* is set to 'true', the SLED MUST operate in a loopback mode.
+
+5) When operating in loopback mode, all Ethernet packets forwarded across the indicated LCI by the eCM will be processed as follows:
+
+- a) If the received Ethernet packet is greater than 1472 octets, the Ethernet packet MUST be split into two fragments according to IP fragmentation scheme as described in [IETF RFC 791], the first consisting of the first 1472 octets of the Ethernet packet and the second containing the remaining octets, resulting in two payloads that are processed as described below.
+
+- b) If the received Ethernet packet is less than or equal to 1472 octets, the entire packet MUST be processed as a single payload.
+  - c) Each payload generated in step 5a or 5b MUST be prepended with the contents of *sledLoopbackPktHdr*.
+  - d) The mutable fields within *sledLoopbackPktHdr* MUST be recomputed. The mutable fields are IP Header Checksum, IP Total Length per [IETF RFC 791], and UDP Checksum, UDP Length per [IETF RFC 768].
+  - e) If the Ethernet packet is fragmented as defined in step 5a, the appropriate IP header fields MUST be updated to indicate IP fragmentation. The IP fragmentation header values will differ depending on if this is the first or second fragment being processed (per [IETF RFC 791]). Further, the final 8-bytes of *sledLoopbackPktHdr* (the UDP header) MUST NOT be prepended to the second fragment.
+  - f) The Ethernet FCS MUST be computed and appended.
+  - g) The resulting Ethernet packet MUST be transmitted to the LCI toward the eCM.
+- 6) When the SLED MIB object *sledLoopbackEnable* is set to 'false', the SLED loopback function MUST be disabled.
+- 7) While the SLED loopback function is enabled, the eCM MUST reject changes to *sledLoopbackInterface* or *sledLoopbackPktHdr*.
+
+Figure 5-16 illustrates the SLED packet loopback encapsulation.
+
+![Diagram of SLED packet loopback encapsulation showing the outer packet structure and a detailed view of the 42-octet loopback encapsulation header.](47a7beddcb8a1b7abdca746967e32bb4_img.jpg)
+
+The diagram illustrates the SLED packet loopback encapsulation. The top part shows the overall packet structure: a 42-octet Loopback encapsulation header, a payload of 64-1518 octets (containing a Downstream Ethernet/802 MAC frame, which may be fragmented into 2 IP fragments if greater than 1472 octets), and a 4-octet FCS. The bottom part provides a detailed view of the 42-octet Loopback encapsulation header, which is composed of five fields: Ethernet MAC Dest Addr (6 octets, set to test station), Ethernet MAC Src. Addr (6 octets, set to eSAFE), Type (2 octets, set to 0800), IP header (20 octets, with Src IP Addr = eSAFE and Dest IP Addr = test station), and UDP header (8 octets). Dashed lines connect the 42-octet header in the top diagram to its constituent fields in the bottom diagram. A small label 'J.126(07)\_F5-16' is present in the bottom right corner.
+
+|                               |  |                                                                                                                  |  |  |          |
+|-------------------------------|--|------------------------------------------------------------------------------------------------------------------|--|--|----------|
+| 42 octets                     |  | 64-1518 octets                                                                                                   |  |  | 4 octets |
+| Loopback encapsulation header |  | <i>Payload: Downstream Ethernet/802 MAC frame<br/>(fragment into 2 IP fragments if greater than 1472 octets)</i> |  |  | FCS      |
+
+  
+
+|                                       |                                |             |                                                                 |            |
+|---------------------------------------|--------------------------------|-------------|-----------------------------------------------------------------|------------|
+| 6 octets                              | 6 octets                       | 2 octets    | 20 octets                                                       | 8 octets   |
+| Ethernet MAC Dest Addr = test station | Ethernet MAC Src. Addr = eSAFE | Type = 0800 | IP header<br>Src IP Addr = eSAFE<br>Dest IP Addr = test station | UDP header |
+
+J.126(07)\_F5-16
+
+Diagram of SLED packet loopback encapsulation showing the outer packet structure and a detailed view of the 42-octet loopback encapsulation header.
+
+**Figure 5-16 – SLED packet loopback encapsulation**
+
+Figure 5-17 illustrates an example of the SLED loopback sequence.
+
+![Sequence diagram showing SLED loopback and packet generation sequences between a Test station, CMTS, and an eDOCSIS device.](67114ecf6da13c97a89aeff0d86885d5_img.jpg)
+
+The diagram illustrates two sequences of interactions between a Test station, a CMTS, and an eDOCSIS device. The eDOCSIS device contains an eCM, LCI, eSAFE, SLED MIB, SLED, Loopback, and Packet Gen components.
+
+**SLED Loopback Sequence:**
+
+- The CMTS sends an **Enable SLED via TLV-11** message to the eDOCSIS device. A note indicates `sledGlobalEnable = 'true'` included in TLV-11 of configuration file.
+- The Test station sends an **Select loopback LCI** message (SNMP SET sledLoopbackInterface to ifIndex of eSAFE LCI) to the eDOCSIS device.
+- The Test station sends a **Set up filters** message (Config. file or SNMP) to pass UDP traffic to LCI to the eDOCSIS device.
+- The Test station sends a **Set up encapsulation** message (Ethernet/UDP header using SLED MIB sledLoopbackPktHdr) to the eDOCSIS device.
+- The Test station sends an **Enable Loopback** message (SNMP SET sledLoopbackEnable='true') to the eDOCSIS device.
+- The eDOCSIS device responds with **Loopback enabled**.
+- The Test station sends a **send packet** message to the eDOCSIS device.
+- The eDOCSIS device responds with **Encapsulate & transmit Ethernet packet received**.
+- If the packet is greater than 1472 octets, the eDOCSIS device sends a message to **Encapsulate and transmit 2nd fragment**.
+- The Test station sends a **Disable Loopback** message (SNMP SET sledLoopbackEnable='false') to the eDOCSIS device.
+- The eDOCSIS device responds with **Loopback disabled**.
+
+**SLED Packet Generation Sequence:**
+
+- The Test station sends a **Select packet gen. LCI** message (SNMP SET sledPktGenInterface to ifIndex of eSafe LCI) to the eDOCSIS device.
+- The Test station sends a **Set up packet payload, packet rate and number of packets** via SNMP SET: sledPktGenPayload, sledPktGenRate, and sledPktGenNumPkts to the eDOCSIS device.
+- The Test station sends a **Start packet transmission** message (SNMP SET sledPktGenTrigger='start') to the eDOCSIS device.
+- The eDOCSIS device responds with `sledPktGenLastTrigger = sysUptime`.
+- The eDOCSIS device sends **Xmit packet #1** to the Test station.
+- The eDOCSIS device sends **Xmit packet #2** to the Test station.
+- The Test station sends an **Abort packet transmission** message (SNMP SET sledPktGenTrigger='stop') to the eDOCSIS device.
+- The eDOCSIS device sends **Xmit last packet** to the Test station.
+- The eDOCSIS device responds with **Packet gen. completed**.
+
+J.126(07)\_F5-17
+
+Sequence diagram showing SLED loopback and packet generation sequences between a Test station, CMTS, and an eDOCSIS device.
+
+Figure 5-17 – SLED packet loopback and generation sequences
+
+##### 5.2.6.2.3 Packet generation protocol
+
+An eDOCSIS device implementing SLED MUST implement the following packet generator protocol:
+
+- 1) The SLED packet generation function is attached to the eCM's LCI associated with the eSAFE by setting SLED MIB *sledPktGenInterface* to the ifIndex number associated with the LCI (per Table 5-1).
+- 2) The SLED MIB object *sledPktGenPayload* is set up to be a complete Ethernet (DIX/802 MAC) packet, including FCS trailer, for transmission across the LCI. The FCS is set to be correct for the packet as specified, and MAY be recalculated by the eCM as required for upstream processing; the SLED is not required to validate the FCS, and a packet with an invalid FCS MAY be transmitted with a corrected FCS.
+- 3) The SLED MIB objects *sledPktGenRate* and *sledPktGenNumPkts* are set to non-zero values.
+- 4) When *sledPktGenInterface* is set to an ifIndex associated with an LCI which supports SLED, *sledPktGenRate* and *sledPktGenNumPkts* are both set to non-zero values, the SLED Packet Generator MUST start to send generated Ethernet packets to the LCI in within 250 ms after *sledPktGenTrigger* is set to 'start'; the SLED SHOULD start to transmit packets to the LCI as soon as possible in order to minimize the amount of time it takes to run tests that use the SLED Packet Generator.
+- 5) When *sledPktGenTrigger* is set to 'start', the SLED Packet Generator MUST set the SLED MIB *sledPktGenLastTrigger* to the current value of the system MIB *sysUptime*.
+- 6) The packets generated by the SLED Packet Generator MUST be the exact copies of the Ethernet packet specified by the SLED MIB *sledPktGenPayload*. The average rate of generated packets MUST be as specified by the SLED MIB *sledPktGenRate*.
+- 7) The packet generation MUST be continued until the total number of generated packets reaches the limit as specified by the SLED MIB *sledPktGenNumPkts*, unless terminated by setting *sledPktGenTrigger* to 'stop'. If *sledPktGenTrigger* is set to 'stop' while packets are being generated, the SLED SHOULD stop packet generation within 1 second.
+- 8) While the previous sequence of SLED packets is still in progress, the eCM MUST reject changes to *sledPktGenInterface*, *sledPktGenPayload*, *sledPktGenNumPkts* or *sledPktGenRate*.
+
+Refer to Figure 5-17 for an illustration of the SLED packet loopback and generation sequences.
+
+### 5.2.7 Firmware download
+
+All eDOCSIS devices MUST support a single secured firmware image download that is used for the entire eDOCSIS device.
+
+With the exception of eDOCSIS devices that contain eSTBs, the download MUST be controlled by the eCM using the DOCSIS secure software download (SSD) mechanisms as specified in [BPI+], [DOCSIS2-RFI] and DOCSIS OSS.
+
+Firmware download for an eDOCSIS device that contains an eSTB (referred to as a Set-top Device) is defined in the following subclauses.
+
+#### 5.2.7.1 Set-top device firmware download
+
+There are two firmware download methods for an eDOCSIS device that contains an eSTB:
+
+- 1) DSM-CC data carousel methods as defined in [CCIF 2.0],
+- 2) DOCSIS secure software download (SSD) mechanisms as defined in [DOCSIS-RFI], [BPI+] and [DOCSIS-OSSI].
+
+Note that OpenCable host 2.0 Set-top devices support the above firmware download methods as specified in [HOST2.0] and [CCIF 2.0].
+
+All other Set-top Devices that do not comply with HOST 2.0 MUST support a mechanism for firmware download. Examples are 1) all the DSM-CC Data Carousel methods [CCIF 2.0], and 2) the DOCSIS SSD method.
+
+Firmware downloads can be triggered either via the eCM or the eSTB depending upon implementation. When a Set-top Device firmware download is triggered via the eCM logical element, the eCM MUST report the status of the firmware download as described in clause 5.2.7.2. When a set-top device firmware download is triggered via the eSTB logical element, the eCM MUST report the status of the firmware download as indicated in clause 5.2.7.3.
+
+#### **5.2.7.2 OSS requirements for firmware downloads initiated by the eCM**
+
+If the Set-top Device supports DOCSIS SSD, then it MUST report the status of a firmware download initiated by the eCM in accordance with the CM requirements in DOCSIS OSS.
+
+If the Set-top Device does not implement DOCSIS SSD mechanisms, its eCM MUST set the docsDevSwOperStatus to other(5). The Set-top Device responds to an attempt to trigger a TFTP upgrade (initiated through SNMP or Configuration File) as follows:
+
+- The Set-top Device MUST ignore DOCSIS SSD triggers through SNMP or Config File TLVs.
+- The Set-top Device MUST remain capable of accepting new software through the non-DOCSIS firmware download mechanism.
+- The Set-top Device MUST report the attempt to trigger a TFTP firmware upgrade by logging the appropriate event at the eCM (via an entry in the docsDevEvTable).
+- The docsDevSwOperStatus MUST remain other(5).
+
+If the Set-top Device does not implement DOCSIS SSD mechanisms, then all the download-related requirements as specified in [BPI+] do not apply. Additionally the eCM in this type of Set-top Device MUST support the BPI+ MIB docsBpi2CodeDownloadControl objects with the following constraints (other objects within docsBpi2CodeDownloadControl are as defined within the MIB):
+
+- docsBpi2CodeDownloadStatusCode always reports other(7);
+- docsBpi2CodeDownloadStatusString always returns the string "DOCSIS SSD not supported".
+
+#### **5.2.7.3 OSS requirements for firmware downloads initiated by the eSTB**
+
+During a firmware download for the Set-top Device which is initiated by the eSTB, the eCM MUST set its MIB objects as follows:
+
+- docsDevSwServer to 0.0.0.0.
+- docsDevSwFilename to the filename of the image the eSTB is downloading.
+- docsDevSwAdminStatus to ignoreProvisioningUpgrade(3).
+- docsDevSwOperStatus to inProgress(1).
+- docsDevSwCurrentVers to the current version of the eDOCSIS device code.
+- docsBpi2CodeDownloadStatusCode to other(7).
+- docsBpi2CodeDownloadStatusString to the string "Set-top Device code file download initialized by the eSTB".
+
+During the download of an image for the Set-top Device which is initiated by the eSTB, the eCM MUST ignore any change to the docsDevSwAdminStatus MIB object. Note that by setting docsDevSwAdminStatus to ignoreProvisioningUpgrade and by fixing this value, the eCM will
+
+ignore any firmware download triggers through the eCM configuration file while a firmware download initiated by the eSTB is taking place. Note also that setting docsDevSwAdminStatus to ignoreProvisioningUpgrade and by fixing this value, the eCM effectively ignores firmware download triggers through SNMP while a firmware download initiated by the eSTB is taking place.
+
+After the download process finishes, the eCM MUST set its MIB objects as follows:
+
+- docsDevSwServer to 0.0.0.0.
+- docsDevSwFilename to the filename of the image that the eSTB intended to download.
+- docsDevSwAdminStatus to ignoreProvisioningUpgrade(3) if the eDOCSIS device firmware download initiated by the eSTB succeeded, or to the value present before the download was initiated if the eDOCSIS device firmware download initiated by the eSTB failed.
+- docsDevSwOperStatus to failed(4) if the eDOCSIS device firmware download initiated by the eSTB failed, or to other(5) if it succeeded.
+- docsDevSwCurrentVers to the current version of the eDOCSIS device code.
+- docsBpi2CodeDownloadStatusCode to codeFileVerified(5) if the eDOCSIS device could verify the firmware download, or codeFileRejected(6) if the eDOCSIS device could not verify the firmware download and therefore rejected it, or to other(7) in any other case.
+- docsBpi2CodeDownloadStatusString to the string "Firmware Download initiated by the eSTB successful" if the eDOCSIS device firmware download initiated by the eSTB succeeded, or "Firmware Download initiated by the eSTB failed".
+
+In the case where the CVC distributed to the Set-top Device through the eSTB fails verification checks (e.g., those defined in OpenCable), the eCM MUST set its MIB objects as follows:
+
+- docsBpi2CodeDownloadStatusCode to other(7).
+- docsBpi2CodeDownloadStatusString to the string "Set-top Device CVC validation failure for CVC distributed through eSTB".
+
+### 5.2.8 eSAFE configuration
+
+It is within the scope of each eSAFE specification to define the configuration mechanisms for each type of eSAFE device. eDOCSIS provides two methods for the direct configuration of eSAFE features via the eCM. Either of these two methods may be used by an eSAFE, both may be used, or neither may be used, as defined in the relevant eSAFE specification. The two methods are:
+
+- eSAFE-MIB Configuration – The eSAFE-MIB can provide eCM MIB objects that can be used to configure a particular type of eSAFE (see Annex B). Such MIB objects can be set via the CM configuration file, or by direct SNMP access to the eCM.
+- eCM Config File Encapsulation – The eCM configuration file can contain eSAFE specific configuration parameters, the details of which are defined by the eSAFE specification. These configuration parameters are encapsulated in the eCM configuration file via the "eCM eSAFE Configuration File TLVs", and are passed to the eSAFE upon validation of the configuration file.
+
+#### 5.2.8.1 eCM config file encapsulation
+
+If the eCM is embedded with one or more eSAFEs that utilize eCM Config File Encapsulation, the eCM MUST recognize the corresponding eCM eSAFE Configuration TLVs as listed in Table 5-13.
+
+**Table 5-13 – eCM eSAFE TLVs**
+
+| Type     | Length | Applies to eSAFE type |
+|----------|--------|-----------------------|
+| 201      | n      | ePS                   |
+| 202      | n      | eRouter               |
+| 203..215 |        | <reserved>            |
+| 216      | n      | eMTA                  |
+| 217      | n      | eSTB                  |
+| 218      |        | <reserved>            |
+| 219      | n      | eTEA                  |
+| 220..231 |        | <reserved>            |
+
+Upon successful validation of the CM MIC, the eCM MUST pass the contents of the appropriate eCM eSAFE Configuration File TLVs to each eSAFE that supports eCM Config File Encapsulation.
+
+The eCM MUST silently ignore eCM eSAFE Configuration File TLVs for eSAFEs that do not exist or that do not support eCM Config File Encapsulation.
+
+The mechanism used to pass eCM eSAFE Configuration File TLVs to the eSAFE is vendor specific. It is in the scope of each eSAFE specification to define the encoding of configuration parameters within the corresponding eSAFE TLV and the rules in case the contents are longer than the 254-octet maximum length of each eCM configuration file TLV instance.
+
+## Annex A
+
+## SLED MIB definition
+
+(This annex forms an integral part of this Recommendation)
+
+An eCM implementing SLED MUST implement the following SLED MIB objects.
+
+```
+SLED-MIB DEFINITIONS ::= BEGIN
+IMPORTS
+    MODULE-IDENTITY,
+    Integer32,
+    OBJECT-TYPE      FROM SNMPv2-SMI
+    TruthValue,
+    Timestamp        FROM SNMPv2-TC
+    OBJECT-GROUP,
+    MODULE-COMPLIANCE FROM SNMPv2-CONF
+    clabProjDocsis  FROM CLAB-DEF-MIB
+    InterfaceIndex  FROM IF-MIB
+;
+
+sledMib MODULE-IDENTITY
+    LAST-UPDATED      "2003123000000Z" -- December 30, 2003
+    ORGANIZATION      "eDOCSIS Working Group"
+    CONTACT-INFO
+        "John Eng
+        Postal:      Cable Television Laboratories, Inc
+        400 Centennial Parkway
+        Louisville, CO 80027
+        U.S.A.
+        Phone:  +1 303-661-9100
+        Fax:    +1 303-661-9199
+        E-mail: mibs@cablelabs.com"
+    DESCRIPTION
+        "This MIB module provides the management objects necessary
+        to configure and invoke the Software Loopback Application
+        for eDOCSIS (SLED) functionality."
+    REVISION      "2003123000000Z" -- December 30, 2003
+    DESCRIPTION
+        "Initial version of the ITU-T eDOCSIS SLED MIB module.
+
+        Acknowledgement:
+        Greg Nakanishi of Motorola, Inc.
+        "
+
+    ::= { clabProjDocsis 13 }
+-- Administrative assignments
+sledNotifications      OBJECT IDENTIFIER ::= { sledMib 0 }
+sledMibObjects         OBJECT IDENTIFIER ::= { sledMib 1 }
+sledMibNotificationsObjects OBJECT IDENTIFIER ::= { sledMib 2 }
+sledMibConformance     OBJECT IDENTIFIER ::= { sledMib 3 }
+
+-- Object Groups
+sledGlobal             OBJECT IDENTIFIER ::= { sledMibObjects 1 }
+sledLoopback           OBJECT IDENTIFIER ::= { sledMibObjects 2 }
+sledPktGen             OBJECT IDENTIFIER ::= { sledMibObjects 3 }
+
+--
+-- The following group describes the objects that apply to
+-- both loopback and packet generator SLED functionality
+--
+```
+
+```
+
+sledGlobalEnable OBJECT-TYPE
+SYNTAX      TruthValue
+MAX-ACCESS  read-write
+STATUS      current
+DESCRIPTION
+    "This object allows the SLED functionality to be enabled/disabled.
+
+    This object may only be updated prior to device registration. If
+    the device has completed registration, any attempt to update
+    the value of this object returns 'notWritable'.
+
+    Prior to registration, if the value of this object is set to
+    'true', the SLED functionality is enabled and access to this MIB is
+    allowed.
+
+    Prior to registration, if the value of this object is set to
+    'false', the SLED functionality is disabled and any attempt to
+    update other objects in this MIB returns 'noAccess'.
+    "
+    DEFVAL {false}
+    ::= { sledGlobal 1 }
+
+--
+-- The following group describes the loopback objects
+--
+sledLoopbackInterface OBJECT-TYPE
+    SYNTAX      InterfaceIndex
+    MAX-ACCESS  read-write
+    STATUS      current
+    DESCRIPTION
+        "The index of the logical CPE interface (LCI) that the SLED
+        loopback function is attached to. If the index does not
+        correspond to a LCI supported by this device, 'wrongValue'
+        is returned.
+
+        Any attempt to set this object while sledLoopbackEnable is
+        set to 'true' returns 'notWritable'."
+        ::= { sledLoopback 1 }
+
+sledLoopbackEnable OBJECT-TYPE
+    SYNTAX      TruthValue
+    MAX-ACCESS  read-write
+    STATUS      current
+    DESCRIPTION
+        "Setting this object to 'true' enables the loopback function.
+        Setting this object to 'false' disables the loopback function.
+        When enabled, all Ethernet packets received by the SLED from the
+        LCI are processed as follows:
+
+        1. If the received Ethernet packet is greater than 1472 octets,
+           the Ethernet packet is split into two fragments, the first
+           consisting of the first 1472 octets of the Ethernet packet
+           and the second containing the remaining octets, resulting in
+           two payloads that are processed as described below. If
+           the received Ethernet packet is less than or equal to 1472
+           octets, the entire packet will be processed as a single payload.
+        2. For each payload generated in step 1, the payload is appended to
+           the contents of sledLoopbackPktHdr.
+        3. The mutable fields within sledLoopbackPktHdr MUST be recomputed.
+           The mutable fields are IP Header Checksum, IP Total Length, UDP
+           Checksum, and UDP Length.
+        4. If the Ethernet packet was fragmented in step 1, the appropriate
+           IP header fields (Flags and Fragment Offset) are updated to
+           indicate IP fragmentation.
+        "
+
+```
+
+- These IP fragmentation header values will differ depending on if this is the first or second fragment being processed.
+5. The Ethernet FCS is computed and appended.
+  6. The resulting Ethernet packet is transmitted to the LCI."
+
+```
+DEFVAL {false}
+::= { sledLoopback 2 }
+```
+
+```
+sledLoopbackPktHdr OBJECT-TYPE
+  SYNTAX      OCTET STRING (SIZE(42))
+  MAX-ACCESS  read-write
+  STATUS      current
+  DESCRIPTION
+    "A properly formatted Ethernet(DIX)+IP+UDP header for use in
+    SLED loopback processing as described in sledLoopbackEnable.
+    The object value contains mutable fields that are recomputed:
+    the IP Header Checksum, IP Total Length, UDP Length,and
+    UDP Checksum. Any attempt to set this object while
+    sledLoopbackEnable is set to 'true' returns 'notWritable'."
+  ::= { sledLoopback 3 }
+```
+
+```
+--
+-- The following group describes the packet generation objects
+--
+```
+
+```
+sledPktGenInterface OBJECT-TYPE
+  SYNTAX      InterfaceIndex
+  MAX-ACCESS  read-write
+  STATUS      current
+  DESCRIPTION
+    "The index of the logical CPE interface (LCI) that the SLED
+    packet generation function is attached to. If the index does
+    not correspond to a LCI supported by the device, 'wrongValue'
+    is returned. Any attempt to set this object while
+    sledPktGenTrigger is set to 'start' returns 'notWritable'."
+  ::= { sledPktGen 1 }
+```
+
+```
+sledPktGenPayload OBJECT-TYPE
+  SYNTAX      OCTET STRING (SIZE(64..1518))
+  MAX-ACCESS  read-write
+  STATUS      current
+  DESCRIPTION
+    "The properly formatted Ethernet packet payload to be generated.
+    Any attempt to set this object while sledPktGenTrigger is set
+    to 'start' returns 'notWritable'."
+  ::= { sledPktGen 2 }
+```
+
+```
+sledPktGenRate OBJECT-TYPE
+  SYNTAX      Integer32
+  MAX-ACCESS  read-write
+  STATUS      current
+  DESCRIPTION
+    "The packet rate (in packets per second) that the SLED is to
+    transmit the packet specified in the sledPktGenPayload. Any
+    attempt to set this object while sledPktGenTrigger is set to
+    'start' returns 'notWritable'."
+  DEFVAL {10}
+  ::= { sledPktGen 3 }
+```
+
+```
+sledPktGenNumPkts OBJECT-TYPE
+  SYNTAX      Integer32
+  MAX-ACCESS  read-write
+  STATUS      current
+```
+
+```
+
+DESCRIPTION
+    "Number of packets to be generated at the rate specified by
+    sledPktGenRate. Any attempt to set this object while
+    sledPktGenTrigger has been set to 'start' will return
+    'notWritable'."
+    DEFVAL {1}
+    ::= { sledPktGen 4 }
+
+sledPktGenTrigger OBJECT-TYPE
+    SYNTAX      INTEGER {
+        start(1),
+        stop(2)
+    }
+    MAX-ACCESS  read-write
+    STATUS      current
+    DESCRIPTION
+        "This object controls the packet generation. Setting this object
+        to 'start' causes the packet generation to begin. Reading this
+        object will return 'start' if a packet generation is in progress,
+        otherwise it will return 'stop'. Setting this object to 'stop'
+        while packet generation is in progress aborts the packet
+        generation. Setting this object to 'start' while packet
+        generation is in progress, 'wrongValue' is returned."
+        DEFVAL {stop}
+        ::= { sledPktGen 5 }
+
+sledPktGenLastTrigger OBJECT-TYPE
+    SYNTAX      TimeStamp
+    MAX-ACCESS  read-only
+    STATUS      current
+    DESCRIPTION
+        "Value of sysUptime when the packet generation was
+        last triggered."
+        ::= { sledPktGen 6 }
+
+-- Conformance information *****
+
+sledMibCompliances OBJECT IDENTIFIER ::= { sledMibConformance 1 }
+sledMibGroups      OBJECT IDENTIFIER ::= { sledMibConformance 2 }
+
+-- Compliance statements
+
+sledMibCompliance MODULE-COMPLIANCE
+    STATUS      current
+    DESCRIPTION
+        "The compliance statement for SLED."
+    MODULE
+
+-- unconditionally mandatory groups
+
+    MANDATORY-GROUPS {
+        sledMibBaseGroup
+    }
+
+    ::= { sledMibCompliances 1 }
+
+sledMibBaseGroup OBJECT-GROUP
+    OBJECTS {
+        sledGlobalEnable,
+        sledLoopbackInterface,
+        sledLoopbackEnable,
+        sledLoopbackPktHdr,
+        sledPktGenInterface,
+    }
+
+```
+
+```
+        sledPktGenPayload,
+        sledPktGenRate,
+        sledPktGenNumPkts,
+        sledPktGenTrigger,
+        sledPktGenLastTrigger
+    }
+    STATUS    current
+    DESCRIPTION
+        "Group of object in SLED MIB"
+        ::= { sledMibGroups 1 }
+END
+```
+
+## Annex B
+
+## eSAFE MIB Definition
+
+(This annex forms an integral part of this Recommendation)
+
+An eCM in an eDOCSIS device implementing an embedded CableHome portal services logical element (ePS) and/or embedded PacketCable multimedia terminal adapter (eMTA) logical element as an eSAFE MUST implement the following eSAFE MIB.
+
+```
+ESAFE-MIB DEFINITIONS ::= BEGIN
+IMPORTS
+    MODULE-IDENTITY,
+    Unsigned32,
+    OBJECT-TYPE                FROM SNMPv2-SMI  --RFC 2578
+    OBJECT-GROUP,
+    MODULE-COMPLIANCE          FROM SNMPv2-CONF  -- RFC 2580
+
+    TruthValue,
+    DateAndTime,
+    PhysAddress                FROM SNMPv2-TC  -- RFC 2579
+
+    SnmpAdminString            FROM SNMP-FRAMEWORK-MIB --RFC 3411
+
+    ifIndex                    FROM IF-MIB --RFC 2863
+
+    clabProjDocsis           FROM CLAB-DEF-MIB
+
+;
+
+esafeMib MODULE-IDENTITY
+    LAST-UPDATED "200702230000Z" -- February 23, 2007
+    ORGANIZATION "Cable Television Laboratories, Inc."
+    CONTACT-INFO
+        "Postal: Cable Television Laboratories, Inc.
+        858 Coal Creek Circle
+        Louisville, CO 80027
+        U.S.A.
+        Phone: +1 303-661-9100
+        Fax: +1 303-661-9199
+        E-mail: mibs@cablelabs.com"
+    DESCRIPTION
+        "This MIB module provides the management objects necessary
+        to configure functionality of eSAFE components of a device
+        implementing an eDOCSIS compliant cable modem and one or
+        more eSAFE elements.
+
+        Copyright 1999-2007 Cable Television Laboratories, Inc.
+        All rights reserved."
+    REVISION "200702230000Z" -- February 23, 2007
+    DESCRIPTION
+        "This revision is published as CM-SP-eDOCSIS-I11."
+
+    REVISION "200607280000Z" -- July 28, 2006
+    DESCRIPTION
+        "This revision is published as CM-SP-eDOCSIS-I09."
+    ::= { clabProjDocsis 14 }
+
+-- Administrative assignments
+
+-- esafeNotifications OBJECT IDENTIFIER ::= { esafeMib 0 }
+esafeMibObjects      OBJECT IDENTIFIER ::= { esafeMib 1 }
+esafeBase            OBJECT IDENTIFIER ::= { esafeMibObjects 1 }
+```
+
+```
+
+esafePsMibObjects OBJECT IDENTIFIER ::= { esafeMibObjects 2 }
+esafeMtaMibObjects OBJECT IDENTIFIER ::= { esafeMibObjects 3 }
+esafeStbMibObjects OBJECT IDENTIFIER ::= { esafeMibObjects 4 }
+esafeErouterMibObjects OBJECT IDENTIFIER ::= { esafeMibObjects 5 }
+
+```
+
+Object Groups
+
+eSAFE Base Objects
+
+```
+
+esafeProvisioningStatusTable OBJECT-TYPE
+    SYNTAX      SEQUENCE OF EsafeProvisioningStatusEntry
+    MAX-ACCESS  not-accessible
+    STATUS      current
+    DESCRIPTION
+        "This table contains the current provisioning
+        status of each implemented eSAFE, and information
+        about the last failure or exception condition in
+        the eSAFE provisioning process, if applicable."
+    ::= { esafeBase 1 }
+
+```
+
+```
+
+esafeProvisioningStatusEntry OBJECT-TYPE
+    SYNTAX      EsafeProvisioningStatusEntry
+    MAX-ACCESS  not-accessible
+    STATUS      current
+    DESCRIPTION
+        "An entry in this table is created for
+        each eSAFE implemented in the eDOCSIS
+        compliant device."
+    INDEX { ifIndex }
+    ::= { esafeProvisioningStatusTable 1 }
+
+```
+
+```
+
+EsafeProvisioningStatusEntry ::= SEQUENCE
+{
+    esafeProvisioningStatusProgress      INTEGER,
+    esafeProvisioningStatusFailureFound  TruthValue,
+    esafeProvisioningStatusFailureFlow   SnmpAdminString,
+    esafeProvisioningStatusFailureEventID  Unsigned32,
+    esafeProvisioningStatusFailureErrorText  SnmpAdminString,
+    esafeProvisioningStatusLastUpdate  DateAndTime
+}
+
+```
+
+```
+
+esafeProvisioningStatusProgress OBJECT-TYPE
+    SYNTAX      INTEGER {
+        notInitiated(1),
+        inProgress(2),
+        finished(3)
+    }
+    MAX-ACCESS  read-only
+    STATUS      current
+    DESCRIPTION
+        "The current state of the eSAFE provisioning process.
+
+        notInitiated(1) indicates that the eSAFE has not yet
+        begun its provisioning process.
+
+        inProgress(2) indicates that the eSAFE is in the process
+        of provisioning.
+
+        finished(3) indicates that the eSAFE completed
+        its provisioning process. Provisioning success
+        or failure information is provided by other
+        objects, including
+
+```
+
+```
+
+        esafeProvisioningStatusFailureFound and
+        cabhPsDevProvState."
+    ::= { esafeProvisioningStatusEntry 1 }
+
+esafeProvisioningStatusFailureFound OBJECT-TYPE
+    SYNTAX      TruthValue
+    MAX-ACCESS  read-only
+    STATUS      current
+    DESCRIPTION
+        "true(1) indicates that the eSAFE encountered
+        an error condition during the provisioning
+        process. An eSAFE could start a looping process
+        from a previous flow step after a failure,
+        therefore this value is retained until the
+        flow step that initially failed eventually
+        passes or is updated with another error
+        condition.
+
+        The eSAFE device needs to reflect in the value of
+        'esafePsProvisioningStatusFailureFound' any recognized
+        errors even if it is still in the process of
+        provisioning, i.e., when
+        esafeProvisioningStatusProgress has a value of
+        inProgress(2)."
+    REFERENCE
+        "PacketCable Provisioning specification,
+        Provisioning Overview section; CableHome
+        specification, Provisioning Processes
+        section, BSoD TDM Emulation Interface Specification,
+        Provisioning section."
+    ::= { esafeProvisioningStatusEntry 2 }
+
+esafeProvisioningStatusFailureFlow OBJECT-TYPE
+    SYNTAX      SnmpAdminString
+    MAX-ACCESS  read-only
+    STATUS      current
+    DESCRIPTION
+        "If esafeProvisioningStatusFailureFound
+        is true(1), this object contains the
+        label for the provisioning flow step
+        in which the error condition was
+        encountered, otherwise an empty value
+        is reported.
+
+        The value of this object corresponds to
+        the provisioning sequence 'Flow Step'
+        designator for the associated eSAFE, as
+        defined in the eSAFE specification. For
+        example, an ePS will report a value like
+        CHPSWMD-1, an eMTA will report a value
+        such as MTA-1, and a TEA will report a value
+        such as eTEA-1."
+    REFERENCE
+        "PacketCable Provisioning specification,
+        Provisioning Overview section; CableHome
+        specification, Provisioning Processes
+        section; BSoD TDM Emulation Interface Specification,
+        provisioning section."
+    ::= { esafeProvisioningStatusEntry 3 }
+
+esafeProvisioningStatusFailureEventID OBJECT-TYPE
+    SYNTAX      Unsigned32 (0..4294967295)
+    MAX-ACCESS  read-only
+    STATUS      current
+
+```
+
+### DESCRIPTION
+
+"If esafeProvisioningStatusFailureFound is true(1), this object contains the eSAFE log error Event Identifier defined in the eSAFE specification, otherwise it returns a value '0'. For an eMTA type eSAFE, this object reports the PacketCable EventID value from the Provisioning Events table, e.g., 65535. For an ePS type eSAFE, this object reports the EventID value from the Defined Events for CableHome table, e.g., 68000100. For an eTEA type eSAFE, this object reports the Event ID value from the 'Event ID' column of the DOCSIS Events Extensions table for BSoD TDM Emulation Interface Specification, e.g., 8000100."
+
+### REFERENCE
+
+"PacketCable Provisioning specification, Appendix I Provisioning Events; CableHome specification, Appendix II Format and Content for Event, SYSLOG, and SNMP Trap; BSoD TDM Emulation Interface Specification, Annex A Event, SYSLOG, and SNMP Trap Extensions."
+
+::={ esafeProvisioningStatusEntry 4 }
+
+### esafeProvisioningStatusFailureErrorText OBJECT-TYPE
+
+SYNTAX SnmpAdminString
+
+MAX-ACCESS read-only
+
+STATUS current
+
+### DESCRIPTION
+
+"If esafeProvisioningStatusFailureFound is true(1), this object contains the eSAFE log error messages based on the eSAFE specification, otherwise it returns an empty value. For an eMTA type eSAFE, this object reports the value from the 'Comments' column of the Provisioning Events table, e.g., 'The DNS Response from the DNS server did not resolve the TFTP FQDN.' For an ePS type eSAFE this object reports the value from the 'Event Text' column of the Defined Events for CableHome table, e.g., 'DHCP Failed - Discover sent, no offer received. For an eTEA type eSAFE, this object reports the value from the 'Event Message' column of the DOCSIS Events Extensions table for BSoD TDM Emulation Interface Specification, e.g., 'TFTP config file download error (eTEA-6).'"
+
+### REFERENCE
+
+"PacketCable Provisioning specification, PacketCable Management Event Mechanism specification; CableHome specification, Appendix II Format and Content for Event, SYSLOG, and SNMP Trap; BSoD TDM Emulation Interface Specification, DOCSIS Events Extensions Annex for Event, SYSLOG, and SNMP Trap Extensions."
+
+::={ esafeProvisioningStatusEntry 5 }
+
+### esafeProvisioningStatusLastUpdate OBJECT-TYPE
+
+SYNTAX DateAndTime
+
+MAX-ACCESS read-only
+
+STATUS current
+
+```
+
+DESCRIPTION
+    "The value of the eCM docsDevDateTime when
+    this row entry was last updated."
+    ::= { esafeProvisioningStatusEntry 6 }
+
+esafeDevStatusTable OBJECT-TYPE
+    SYNTAX      SEQUENCE OF EsafeDevStatusEntry
+    MAX-ACCESS  not-accessible
+    STATUS      current
+    DESCRIPTION
+        "This table contains entries that provide the SNMP manager
+        with status information pertaining to each implemented
+        eSAFE device. While this table MUST be implemented by all
+        eDOCSIS devices, the support for reporting such information
+        and the status conditions supported will be determined by
+        the corresponding eSAFE specifications. It is highly
+        recommended that the eSAFE MIBs themselves have objects
+        to specify more detailed information."
+        ::= { esafeBase 2 }
+
+esafeDevStatusEntry OBJECT-TYPE
+    SYNTAX      EsafeDevStatusEntry
+    MAX-ACCESS  not-accessible
+    STATUS      current
+    DESCRIPTION
+        "An entry in this table MUST be created for each eSAFE
+        device behind the eCM. The index needs to be the
+        corresponding index in the ifTable for the associated
+        eSAFE device."
+    INDEX { ifIndex }
+    ::= { esafeDevStatusTable 1 }
+
+esafeDevStatusEntry ::=SEQUENCE
+{
+    esafeDevServiceIntImpact INTEGER,
+    esafeDevServiceIntImpactInfo SnmpAdminString
+}
+
+esafeDevServiceIntImpact OBJECT-TYPE
+    SYNTAX      INTEGER {
+        significant(1),
+        none(2),
+        unsupported(3)
+    }
+    MAX-ACCESS  read-only
+    STATUS      current
+    DESCRIPTION
+        "The value of this MIB object indicates the service
+        interruption impact assessment of the corresponding eSAFE
+        device as determined by the current status of the eSAFE
+        device, in accordance with the directives provided in the
+        eSAFE specification.
+
+        If esafeDevServiceIntImpact is set to significant (1), it
+        indicates that the corresponding eSAFE device (as per the
+        eSAFE specification) identifies a significant impact on the
+        active services at the given point in time. This impact
+        level is highly recommended for critical or real-time
+        services, though the impact assessment is left to the
+        directives provided by the associated eSAFE specification.
+    "
+}
+
+```
+
+If esafeDevServiceIntImpact is set to none (2), it indicates that the corresponding eSAFE device (as per the eSAFE specification) identifies no significant impact on the services offered at the given point in time.
+
+If esafeDevServiceIntImpact is unsupported(3), it indicates that the corresponding eSAFE device has no known interfaces to support this feature or the eSAFE specification does not recommend this feature.
+
+If the eSAFE specification specifies the use of this mechanism, then it MUST define definitive states for the impacts (significant or none) and the value of unsupported(3) MUST not be used by the eDOCSIS device for that eSAFE interface.
+
+However, if the corresponding eSAFE specification does not provide any directives, then the value MUST be set to unsupported(3).
+
+If there exists multiple services being offered by an eSAFE device (Either multiple services or multiple instances of the same service), this MIB MUST indicate the highest possible impact and other impact information SHOULD be populated in the associated esafeDevServiceIntImpactInfo table."
+
+::={ esafeDevStatusEntry 1 }
+
+esafeDevServiceIntImpactInfo OBJECT-TYPE
+
+SYNTAX SnmpAdminString
+
+MAX-ACCESS read-only
+
+STATUS current
+
+DESCRIPTION
+
+"This object provides more information to the SNMP Managers regarding the condition reported in esafeDevServiceIntImpact. The eSAFE device vendor could use this to fill in specific vendor strings or values that could add value or provide more information related to the status.
+
+Examples:
+
+For eMTA devices:
+
+Lines 1 and 3 have active connections, Line 2 is not provisioned.
+
+<Value of the corresponding MIB object in the eMTA MIBs, if applicable>
+
+For other eSAFE devices:
+
+Critical video streaming in progress, please wait for 5.30 minutes
+
+<Value of the corresponding MIB object in the eSAFE MIBs, if applicable>.
+
+The device MUST report 'No Additional Information' in case the associated eSAFE vendor cannot obtain information from the eSAFE device."
+
+::={ esafeDevStatusEntry 2 }
+
+--
+
+-- Objects that apply to an eCM with an ePS type eSAFE.
+
+--
+
+```
+
+esafePsCableHomeModeControl OBJECT-TYPE
+    SYNTAX      INTEGER {
+        disabledMode(1),
+        provSystem(2),
+        dormantCHMode(3)
+    }
+    MAX-ACCESS  read-write
+    STATUS      current
+    DESCRIPTION
+        "This object provides control over the mode of
+        operation of the CableHome ePS eSAFE element
+        of the eDOCSIS compliant device.
+
+        When this object is set to disabledMode(1), the
+        ePS eSAFE element is instructed to switch to
+        CableHome Disabled Mode operation.
+
+        When this object is set to provSystem(2), the ePS
+        eSAFE element restarts its provisioning process.
+
+        When this object is set to dormantCHMode(3), the ePS
+        eSAFE element is instructed to switch to CableHome
+        Dormant Mode operation. In this mode, the ePS restarts
+        its provisioning process omitting CableHome-specific
+        DHCP Options 60 and 43 in the DHCP DISCOVER and
+        DHCP REQUEST messages, acquires an IP address lease from
+        the cable operator's DHCP server, and operates in unmanaged
+        Dormant CableHome Mode regardless of the values of the file
+        and siaddr fields or of the values of DHCP options that
+        might otherwise configure the ePS to operate in DHCP
+        Provisioning Mode or in SNMP Provisioning Mode.
+
+        The value of this object MUST persist across cable modem
+        resets."
+    REFERENCE
+        "CableHome specifications, CableHome Operational
+        Modes section."
+    DEFVAL { dormantCHMode }
+    ::= { esafePsMibObjects 1 }
+
+esafePsCableHomeModeStatus OBJECT-TYPE
+    SYNTAX      INTEGER {
+        disabledMode(1),
+        dormantCHMode(2),
+        cableHomeMode(3)
+    }
+    MAX-ACCESS  read-only
+    STATUS      current
+    DESCRIPTION
+        "This object provides visibility to the current
+        mode of operation of the CableHome ePS eSAFE
+        element of the eDOCSIS compliant device.
+
+        If the value of this object is disabledMode(1), the
+        ePS eSAFE element is currently operating in CableHome
+        Disabled Mode.
+
+        If the value of this object is dormantCHMode(2), the
+        ePS is currently operating in Dormant CableHome Mode.
+
+        If the value of this object is cableHomeMode(3), the ePS
+        is currently operating in CableHome mode."
+
+```
+
+### REFERENCE
+
+"CableHome specification, CableHome Operational Models section."
+
+::= { esafePsMibObjects 2 }
+
+--
+
+-- Objects that apply to an eCM with an eRouter type eSAFE.
+
+--
+
+### esafeErouterAdminMode OBJECT-TYPE
+
+SYNTAX INTEGER {
+
+disabled(1),  
+ipv4Only(2),  
+ipv6Only(3),  
+ipv4AndIpv6(4)
+
+}
+
+MAX-ACCESS read-only
+
+STATUS current
+
+### DESCRIPTION
+
+"This object provides visibility to the mode of operation to which the DOCSIS eRouter eSAFE element was set via TLV in the cable modem configuration file.
+
+If the value of this object is disabled(1), the eRouter was configured via TLV in the cable modem configuration file to not initialize as described in the eRouter Initialization section of the CableLabs IPv4 and IPv6 eRouter Specification.
+
+If the value of this object is ipv4Only(2), the eRouter was configured via TLV in the cable modem configuration file to operate with an IPv4 network address and with the IPv4 stack operational and to operate without an IPv6 network address and to not run an IPv6 protocol stack.
+
+If the value of this object is ipv6Only(3), the eRouter was configured via TLV in the cable modem configuration file to operate with an IPv6 network address and with the IPv6 stack operational and to operate without an IPv4 network address and to not run an IPv4 protocol stack.
+
+If the value of this object is ipv4AndIpv6(4), the eRouter was configured via TLV in the cable modem configuration file to operate with an IPv4 network address and an IPv6 network address and to run both IPv4 and IPv6 protocol stacks."
+
+### REFERENCE
+
+"DOCSIS IPv4 and IPv6 eRouter Specification, CM-SP-eRouter-I02-070223."
+
+::= { esafeErouterMibObjects 1 }
+
+### esafeErouterOperMode OBJECT-TYPE
+
+SYNTAX INTEGER {
+
+disabled(1),  
+ipv4OnlyFwding(2),  
+ipv6OnlyFwding(3),  
+ipv4AndIpv6Fwding(4),  
+noIpv4AndNoIpv6Fwding(5)
+
+}
+
+MAX-ACCESS read-only
+
+STATUS current
+
+### DESCRIPTION
+
+"This object provides visibility to the current mode of operation of the DOCSIS eRouter eSAFE element of the eDOCSIS compliant device.
+
+If the value of this object is disabled(1), the eRouter eSAFE element has been administratively Disabled. The eDOCSIS device will bridge traffic according to the configuration of the DOCSIS embedded cable modem (eCM)
+
+If the value of this object is ipv4OnlyFwding(2), the eRouter eSAFE element is currently operating with the IPv4 protocol stack operational, is forwarding IPv4 traffic, and is not running an IPv6 protocol stack and not forwarding IPv6 traffic.
+
+If the value of this object is ipv6OnlyFwding(3), the eRouter eSAFE element is currently operating with the IPv6 protocol stack operational, is forwarding IPv6 traffic, and is not running an IPv4 protocol stack and not forwarding IPv4 traffic.
+
+If the value of this object is ipv4AndIpv6Fwding(4), the eRouter eSAFE element is currently operating with both the IPv4 protocol stack and IPv6 protocol stack operational, and is forwarding IPv4 and IPv6 traffic.
+
+If the value of this object is noIpv4AndNoIpv6Fwding(5), the eRouter is currently operating with neither the IPv4 nor IPv6 protocol stack running. The eRouter is unable to pass traffic between the Operator-Facing Interface and the Customer-Facing Interface. "
+
+### REFERENCE
+
+"DOCSIS IPv4 and IPv6 eRouter Specification,  
+CM-SP-eRouter-I02-070223."  
+::= { esafeErouterMibObjects 2 }
+
+### esafeErouterPhysAddress OBJECT-TYPE
+
+SYNTAX PhysAddress
+
+MAX-ACCESS read-only
+
+STATUS current
+
+### DESCRIPTION
+
+"The physical address of the operator-facing interface of the DOCSIS eRouter eSAFE element."  
+::= { esafeErouterMibObjects 3 }
+
+### -- Conformance information
+
+esafeMibConformance OBJECT IDENTIFIER ::= { esafeMib 2 }  
+esafeMibCompliances OBJECT IDENTIFIER ::= { esafeMibConformance 1 }  
+esafeMibGroups OBJECT IDENTIFIER ::= { esafeMibConformance 2 }
+
+### -- Compliance statements
+
+### esafeMibBasicCompliance MODULE-COMPLIANCE
+
+STATUS current
+
+### DESCRIPTION
+
+"The compliance statement for eSAFE MIB objects."
+
+MODULE -- eSAFE-MIB
+
+```
+
+-- unconditionally mandatory groups
+
+MANDATORY-GROUPS {
+    esafeBaseGroup
+}
+
+-- conditionally mandatory groups
+
+GROUP esafePsMibGroup
+    DESCRIPTION
+        "This group is implemented only by eDOCSIS devices
+        that implement an embedded Portal Services logical
+        element (ePS) compliant with CableLabs
+        CableHome specifications."
+
+GROUP esafeERouterMibGroup
+    DESCRIPTION
+        "This group is implemented only by eDOCSIS devices
+        that implement a DOCSIS embedded router (eRouter)
+        element compliant with CableLabs DOCSIS eRouter
+        specifications."
+    ::= { esafeMibCompliances 1 }
+
+-- eSAFE Base Group Declarations
+
+esafeBaseGroup OBJECT-GROUP
+    OBJECTS {
+        esafeProvisioningStatusProgress,
+        esafeProvisioningStatusFailureFound,
+        esafeProvisioningStatusFailureFlow,
+        esafeProvisioningStatusFailureEventID,
+        esafeProvisioningStatusFailureErrorText,
+        esafeProvisioningStatusLastUpdate,
+        esafeDevServiceIntImpact,
+        esafeDevServiceIntImpactInfo
+    }
+    STATUS        current
+    DESCRIPTION
+        "Group of eSAFE Base objects in the eSAFE MIB."
+    ::= { esafeMibGroups 1 }
+
+-- PS MIB Group
+
+esafePsMibGroup OBJECT-GROUP
+    OBJECTS {
+        esafePsCableHomeModeControl,
+        esafePsCableHomeModeStatus
+    }
+    STATUS        current
+    DESCRIPTION
+        "Group of embedded PS-specific objects
+        in the eSAFE MIB."
+    ::= { esafeMibGroups 2 }
+
+-- eRouter MIB Group
+
+esafeERouterMibGroup OBJECT-GROUP
+    OBJECTS {
+        esafeERouterAdminMode,
+        esafeERouterOperMode,
+        esafeERouterPhysAddress
+    }
+}
+
+```
+
+```
+STATUS      current
+DESCRIPTION
+    "Group of embedded Router-specific objects
+     in the eSAFE MIB."
+:: = { esafeMibGroups 3 }
+```
+
+```
+END
+```
+
+# Annex C
+
+## Format and content for eCM/eSTB event, SYSLOG, and SNMP trap extensions
+
+(This annex forms an integral part of this Recommendation)
+
+To facilitate device provisioning and fault management, the eCM of a Set-top Device MUST support the DOCSIS Event extensions defined in this annex.
+
+This annex is an extension of Annex D Format and Content for Event, SYSLOG, and SNMP Trap (normative) of [DOCSIS2-OSSI].
+
+**Table C.1 – eDOCSIS events extensions**
+
+| Set-top device software upgrade |                            |             |                                                                            |                           |                |          |                               |
+|---------------------------------|----------------------------|-------------|----------------------------------------------------------------------------|---------------------------|----------------|----------|-------------------------------|
+| Process                         | Sub-process                | CM priority | Event message                                                              | Message notes and details | Error code set | Event ID | Trap name                     |
+| SW Upgrade                      | SW Upgrade General Failure | Notice      | DOCSIS SSD not supported                                                   |                           | H01.1          | 72000101 |                               |
+| SW Upgrade                      | Verification of CVC        | Error       | Set-top Device CVC validation failure for CVC distributed through the eSTB |                           | H01.2          | 72000102 | docsDevCmSwUpgradeCVCFailTrap |
+| SW Upgrade                      | SW Upgrade Init            | Notice      | Set-top Device code file download initialized through the eSTB             |                           | H01.3          | 72000103 | docsDevCmSwUpgradeInitTrap    |
+| SW Upgrade                      | SW Upgrade General Failure | Error       | Set-top Device code file download through the eSTB failed                  |                           | H01.4          | 72000104 | docsDevCmSwUpgradeFailTrap    |
+| SW Upgrade                      | SW Upgrade Success         | Notice      | Set-top Device code file successfully downloaded through the eSTB          |                           | H01.5          | 72000105 | docsDevCmSwUpgradeSuccessTrap |
+
+
+
+
+
+## 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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@@ -0,0 +1,541 @@
+
+
+![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
+
+**J.127**
+
+(06/2004)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Interactive systems for digital television distribution
+
+---
+
+**Transmission protocol for multimedia  
+webcasting over TCP/IP networks**
+
+ITU-T Recommendation J.127
+
+---
+
+
+
+# **ITU-T Recommendation J.127**
+
+# **Transmission protocol for multimedia webcasting over TCP/IP networks**
+
+# **Summary**
+
+This Recommendation defines a transmission protocol for multimedia webcasting over TCP/IP networks. The protocol consists of a presentation description and session control. The presentation description is based on the XHTML format, and it specifies properties of the media such as URI, content type, content size, accounting information, and so on. First of all, a terminal receives the presentation description, and sets up in accordance with the description. Then the terminal starts transmission of the media in accordance with the session control, which is based on HTTP. The session control supports starting the session, retrieving the media data and ending the session. In addition, a remote camera control scheme is also defined in the session control. Since the protocol defined in this Recommendation is similar to the WWW browsing system, problems related to the UDP/IP streaming such as the Firewall issue are resolved by this Recommendation, and the implementation will have less affect.
+
+## **Source**
+
+ITU-T Recommendation J.127 was approved on 29 June 2004 by ITU-T Study Group 9 (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 2004
+
+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 |
+| 2.1 | Normative references.....                  | 1 |
+| 2.2 | Informative references.....                | 1 |
+| 3   | Terms and definitions .....                | 1 |
+| 4   | Abbreviations.....                         | 2 |
+| 5   | Presentation Description.....              | 2 |
+| 5.1 | XHTML Presentation Description Format..... | 2 |
+| 5.2 | <object> Element .....                     | 3 |
+| 5.3 | <param> Element .....                      | 4 |
+| 6   | Session control.....                       | 6 |
+| 6.1 | Retrieval of the content size .....        | 6 |
+| 6.2 | Data transmission .....                    | 7 |
+| 6.3 | Normal termination .....                   | 8 |
+| 6.4 | Abnormal termination .....                 | 8 |
+| 6.5 | Camera control .....                       | 9 |
+
+
+
+# ITU-T Recommendation J.127
+
+## Transmission protocol for multimedia webcasting over TCP/IP networks
+
+# 1 Scope
+
+This Recommendation defines a transmission protocol for multimedia webcasting of various media format over TCP/IP networks. Such formats include J.123 and J.124 as well as other media formats. However, the protocol defined in this Recommendation is independent from the media format, which is outside the scope of this Recommendation.
+
+The protocol consists of a presentation description and session control. The presentation description is based on the XHTML format, and the session control is based on HTTP. Issues not especially specified here shall comply with XHTML and HTTP.
+
+# 2 References
+
+## 2.1 Normative 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] W3C Recommendation, XHTML 1.0: *The Extensible HyperText Markup Language*.
+- [2] IETF RFC 2068 (1997), *Hypertext Transfer Protocol – HTTP/1.1*.
+
+## 2.2 Informative references
+
+- [3] ITU-T Recommendation J.123 (2002), *Multiplexing format for webcasting on TCP/IP network*.
+- [4] ITU-T Recommendation J.124 (2004), *Multiplexing format for multimedia webcasting over TCP/IP networks*.
+
+# 3 Terms and definitions
+
+This Recommendation defines the following terms:
+
+- 3.1 file downloading:** Program transmission method whereby the program starts playing after the entire data has been downloaded.
+- 3.2 live transmission:** Program transmission method whereby the program starts playing after a certain amount of data has been buffered while receiving subsequent data in the background, where the program is fed in real time by the content provider.
+- 3.3 VoD transmission:** Program transmission method whereby the program starts playing after a certain amount of data has been buffered while receiving subsequent data in the background, where the program is completely created by the content provider.
+
+# 4 Abbreviations
+
+This Recommendation uses the following abbreviations:
+
+HTTP Hypertext Transfer Protocol
+
+MIME Multipurpose Internet Mail Extensions
+
+VoD Video-on-Demand
+
+XHTML Extensible HyperText Markup Language
+
+# 5 Presentation Description
+
+## 5.1 XHTML Presentation Description Format
+
+The overall program and the properties of the media shall be defined by a presentation description in XHTML [1]. The presentation description may be obtained by the receiver using HTTP or other means such as e-mail and may not necessarily be stored on the server.
+
+The presentation description contains a description of the media streams making up the program, including their location, title, encoding types, data size, and other parameters that enable the receiver to start retrieving the most appropriate media.
+
+The presentation description is written by the <object> element with the <param> elements of XHTML.
+
+An example is shown below. Elements defined by this Recommendation are written with bold letters.
+
+```
+<?xml version="1.0" ?>
+<!DOCTYPE html
+  PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
+<head>
+<title>Webcasting Test Page</title>
+</head>
+<body>
+  <object data="http://www.webcasting.org/media.mp4" type="video/MP2T"
+    copyright="no" standby="Click Here">
+    <param name="disposition" value="devmpzz" valuetype="data" />
+    <param name="duration" value="30000" valuetype="data" />
+    <param name="size" value="240000" valuetype="data" />
+    <param name="title" value="Preview of the movie" valuetype="data" />
+    <param name="ac" value="Jc5gUxzTqJ9ebM3U18GEWdKgtiTWR6Fe" valuetype="data" />
+  </object>
+</body>
+</html>
+```
+
+Elements used in the presentation description are summarized in Table 1. In Table 1, M/O stands for "Mandatory" or "Optional", respectively.
+
+**Table 1/J.127 – Elements defined in this Recommendation**
+
+| Element | Attribute                                              | M/O | Value          | Description                                                                                              |
+|---------|--------------------------------------------------------|-----|----------------|----------------------------------------------------------------------------------------------------------|
+| object  | data                                                   | M   | URI String     | Actual location of the media file.                                                                       |
+| object  | type                                                   | M   | MIME Type      | MIME type of the media.                                                                                  |
+| object  | copyright                                              | O   | "yes"   "no"   | Copyright control.                                                                                       |
+| object  | standby                                                | M   | String         | The displayed text of the link.                                                                          |
+| param   | name="ac"<br>value="...."<br>valuetype="data"          | O   | String         | Access Ticket.                                                                                           |
+| param   | name="bitrate"<br>value="...."<br>valuetype="data"     | O   | Numeric String | Bit rate of the content in bit/s.                                                                        |
+| param   | name="camctl"<br>value="...."<br>valuetype="data"      | O   | Numeric String | Camera control capability.                                                                               |
+| param   | name="disposition"<br>value="...."<br>valuetype="data" | M   | String         | Types of the content distribution, which stands for downloading, VoD transmission, or live transmission. |
+| param   | name="duration"<br>value="...."<br>valuetype="data"    | O   | Numeric String | Duration of the content in milliseconds.                                                                 |
+| param   | name="size"<br>value="...."<br>valuetype="data"        | O   | Numeric String | File size of the content in bytes. This field is effective for downloading and VoD streaming.            |
+| param   | name="title"<br>value="...."<br>valuetype="data"       | M   | String         | Title text of the content.                                                                               |
+
+## 5.2 <object> Element
+
+The following attributes for the <object> element are defined in this Recommendation.
+
+### 5.2.1 data
+
+This is a mandatory attribute that specifies the URI of the media to be transmitted. In this Recommendation, since the media is transmitted by HTTP, the scheme of the URI shall be http, or the URI shall start with "http://".
+
+### 5.2.2 type
+
+This is a mandatory attribute that specifies the MIME type of the media to be transmitted. For example, "video/MP2T" is specified for MPEG-2 Transport Stream.
+
+### 5.2.3 copyright
+
+This attribute takes "yes" or "no", and this is optional. The default value is "no". The copyright attribute takes effect as follows.
+
+yes: The content is protected from storing. The media data cannot be stored in the device after playing.
+
+no: The media data can be stored in the device after playing.
+
+If this attribute is not specified, the terminal shall handle the file as storing allowed.
+
+### 5.2.4 standby
+
+This is a mandatory attribute that specifies the displayed text of the link to the media. It will typically be "Click Here" or the name of the content.
+
+## 5.3 <param> Element
+
+Parameters of the media are specified with the <param> element in the HTML description. The following parameters are defined in this Recommendation. Each parameter is identified by the name attribute and the value is specified by the value attribute. For the all parameters, valuetype="data" shall be included in each <param> element.
+
+The terminal shall ignore unknown parameters.
+
+### 5.3.1 ac
+
+This is an optional parameter and the value attribute specifies the access ticket. The maximum length of the value is 512 bytes. The terminal that obtained the access ticket from the ac parameter in the presentation description shall use this ticket when the terminal carries out the session control as "ac=" parameter in the HTTP request. See also clause 6.
+
+This is used for identification of fee collection.
+
+### 5.3.2 bitrate
+
+This is an optional parameter. It specifies the total bit rate of the media in bits per second. If the media has video and audio track, the bitrate value will be the sum of the bit rate of each track.
+
+If the media has multiple bit rates for adaptive bit rate changing, all the values are specified with ':' separator. For example,
+
+<param name="bitrate" value="64000:128000:256000" valuetype="data" />
+
+### 5.3.3 camctl
+
+This is an optional parameter that shows the camera control capability of the content. The value consists of 8-numeric letters and each digit shows the capability of each camera control. The following table explains the camera control value (= "XYZABCDE"), where the left-most digit is firstly described.
+
+**Table 2/J.127 – Camera control parameters**
+
+| No. | Value  | Description                                      |
+|-----|--------|--------------------------------------------------|
+| 1   | 0 or 1 | If the value is 1, panning control is supported. |
+| 2   | 0 or 1 | If the value is 1, tilting control is supported. |
+| 3   | 0 or 1 | If the value is 1, zooming control is supported. |
+| 4   | 0      | Reserved                                         |
+| 5   | 0      | Reserved                                         |
+| 6   | 0      | Reserved                                         |
+| 7   | 0      | Reserved                                         |
+| 8   | 0      | Reserved                                         |
+
+For example, the following shows the case where the content supports the pan and the zoom control.
+
+**<param name="camctl" value="10100000" valuetype="data" />**
+
+- The "camctl" parameter is effective only for the camera control enabled content, which is specified by the "disposition" parameter described below.
+- The terminal shall recognize the content has camera control capability only when the "camctl" parameter exists and the value has an appropriate setting.
+- The terminal shall recognize the content has no camera control capability if the value is not specified or the value is "00000000".
+- The terminal shall recognize the content has no camera control capability if the value has more than eight digits or less than eight digits.
+- The terminal shall recognize the content has no camera control capability if the value contains any digits other than 0 or 1.
+- The terminal shall ignore the "camctl" parameter if any reserved field contains a non-zero.
+
+Actual actions for the camera control are described in 6.5.
+
+### 5.3.4 disposition
+
+The disposition parameter defines the content type, its application, distribution scheme, and so on. The existence of the disposition parameter is mandatory. In this Recommendation, the disposition parameter itself is not defined, but what the parameter specifies is defined as follows.
+
+- Category of the content: Video (including Video and Audio), Audio, Voice, MIDI, Still Image, Animation, Application Program (e.g., JAVA), etc.
+- Transmission scheme of the content: File downloading, VoD transmission, Live transmission.
+- Purpose of the content: Just viewing, Storing, Particular use (Wallpaper, Screensaver, Alarm, etc.).
+
+### 5.3.5 duration
+
+This is an optional parameter. It specifies the duration of the media in milliseconds. If the media has different duration of video and audio track, the value is the longest duration in the tracks.
+
+### 5.3.6 size
+
+This is an optional parameter. It specifies the data size of the media in bytes, which helps the terminal to obtain the content size in advance of transmitting. Regarding the file downloading and the VoD transmission, the file is already created before transmitting. Therefore, the value of the size parameter is the same as the size of the file.
+
+In addition, if the media has multiple bit rates for adaptive bit rate changing, each size corresponding to each bit rate is specified with ':' separator. For example,
+
+**<param name="size" value="240000:480000:960000" valuetype="data" />**
+
+If this parameter is not specified in the presentation description, the terminal shall require the content size from the server at the beginning of the transmission. This is carried out with the HEAD request of HTTP. Details are described in 6.1.
+
+For the live transmission, the file size cannot be estimated before transmission. In this case, the size value indicates the maximum size of the stream that is continuously transmitted. For example, if the size is 1572864 for the live transmission, the connection will be closed after receiving 1.5 MB of the content.
+
+### 5.3.7 title
+
+This is a mandatory parameter that describes the title of the content. The maximum length of the value is 40 bytes. The title may be shown on the terminal when the content is playing.
+
+# 6 Session control
+
+In this Recommendation, all session controls are based on HTTP. Some commands are embedded in the HTTP-URI query part and some are sent to the server in the HTTP request header.
+
+After retrieving the presentation description, the terminal issues the HTTP request in order to start the session. The following defines the session control in this Recommendation.
+
+## 6.1 Retrieval of the content size
+
+For the file downloading and the VoD streaming, the terminal shall obtain the size of the content unless the size parameter exists in the presentation description. This is done with the HEAD method of HTTP as follows.
+
+Syntax:
+
+**HEAD /URI?ac=xxxx&br=128000&ts=1 HTTP/1.1**
+
+| Item           | M/O | Description                                                           |
+|----------------|-----|-----------------------------------------------------------------------|
+| Method         | M   | HEAD                                                                  |
+| URI            | M   | URI obtained from the presentation description.                       |
+| URI Parameters | ac  | O Access ticket obtained from the presentation description.           |
+|                | br  | O Bit rate selection in accordance with the presentation description. |
+|                | ts  | M 1<br>This parameter shall exist if ac is contained.                 |
+
+M/O stands for "Mandatory" or "Optional" respectively.
+
+The following defines the response expected to the request.
+
+**HTTP/1.1 200 OK**
+
+**Content-Length:**
+
+| Item        | M/O            | Description                |
+|-------------|----------------|----------------------------|
+| Status Code | M              | 200 OK                     |
+| Header      | Content-Length | M The size of the content. |
+
+The Content-Length header shall be returned only when the status is successful (200 OK). Other headers might be embedded in the response. The terminal shall ignore unknown headers.
+
+Status codes other than those described above are defined in HTTP [2].
+
+## 6.2 Data transmission
+
+Request of the data transmission is defined as follows.
+
+| Item           |                              | M/O | Description                                                                                                                             |
+|----------------|------------------------------|-----|-----------------------------------------------------------------------------------------------------------------------------------------|
+| Method         |                              | M   | GET                                                                                                                                     |
+| URI            |                              | M   | URI obtained from the presentation description.                                                                                         |
+| URI Parameters | data                         | O   | None: File downloading<br>evdo-2: Live transmission<br>evdo-4: VoD transmission                                                         |
+|                | ac                           | O   | Access Ticket obtained from the presentation description.                                                                               |
+|                | br                           | O   | Bit rate selection in accordance with the presentation description.                                                                     |
+|                | st                           | O   | Specifies the start position of the transmission in milliseconds.<br>Effective only for the initial transmission request, where ts = 2. |
+|                | ts                           | M   | 2: The beginning of the transmission<br>3: Continuous transmission<br>This parameter shall exist if ac is contained.                    |
+| Header         | Range                        | M   | bytes = 0-XXXXX (The beginning of the transmission)<br>bytes = YYYYY-ZZZZZ (Subsequent transmission)                                    |
+|                | x-up-devcap-streaming-camctl | O   | See 6.5.<br>get_control: Camera control ticket is requested with the HTTP request.<br>pan±X, tilt±X, zoom±X: Camera control commands.   |
+
+M/O stands for "Mandatory" or "Optional" respectively.
+
+Response to the data transmission request is defined as follows.
+
+| Item        |                    | M/O | Description                                                                                                                                                |
+|-------------|--------------------|-----|------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Status Code |                    | M   | 206 Partial Content                                                                                                                                        |
+| Parameters  | Content-Range      | M   | bytes = xxxx-xxxx/xxxxxx<br>The size transmitted                                                                                                           |
+|             | x-streaming-camctl | O   | See 6.5.<br>XXX (digits, in seconds)<br>Valid period of the camera control ticket. Maximum value is 999 (seconds).                                         |
+|             | x-streaming-campos | O   | See 6.5.<br>pan±X, tilt±X, zoom±X<br>If the camera control parameter is contained in the request, the current camera position is returned in the response. |
+
+Regarding the Range parameter, the start bytes shall correspond to the actual bytes received at the previous request. The following table shows an example. Note that the Range parameter does not specify an actual position of the content in the server but specifies the number of bytes expected through the transmission.
+
+| The request number | Specified bytes in the request | Actual bytes in the response |
+|--------------------|--------------------------------|------------------------------|
+| 1                  | 0-96767                        | 48000                        |
+| 2                  | 48000-144767                   | 52000                        |
+| 3                  | 100000-196767                  | 50000                        |
+
+Consequently, the request syntax is shown as follows.
+
+**GET /URI?data=evdo-4&ac=xxxx&br=128000&ts=2 HTTP/1.1 (The first request)**  
+**Range:bytes=0-96767**
+
+The following is the response expected to the request.
+
+**HTTP/1.1 206 Partial Content**  
+**Content-Range: bytes 0-48000/1572864**
+
+The subsequent request will be as follows.
+
+**GET /URI?data=evdo-4&ac=xxxx&br=128000&ts=3 HTTP/1.1 (The subsequent request)**  
+**Range:bytes=48000-144767**
+
+The following is the response to the subsequent request.
+
+**HTTP/1.1 206 Partial Content**  
+**Content-Range: bytes 48000-96000/1572864**
+
+Request and response are repeated until the media data is completely received.
+
+## 6.3 Normal termination
+
+For the VoD transmission and the live transmission, the terminal shall issue the termination request after receiving data of the requested size.
+
+Syntax:
+
+**GET /URI?ac=xxxx&ts=4 HTTP/1.1**
+
+| Item   | M/O | Description                                               |
+|--------|-----|-----------------------------------------------------------|
+| Method | M   | GET                                                       |
+| URI    | M   | URI obtained from the presentation description.           |
+| ac     | O   | Access Ticket obtained from the presentation description. |
+| ts     | M   | 4<br>This parameter shall exist if ac is contained.       |
+
+- For the file downloading, it is not necessary to send the termination request.
+- When the terminal receives the response to this request, the VoD/live transmission is finished. The response will be "200 OK" or similar, and the terminal should ignore it.
+
+## 6.4 Abnormal termination
+
+For the VoD transmission and the live transmission, the terminal shall issue the abnormal termination request when a transmission error occurs. For example, the case is regarded as a transmission error where the expected size of the content cannot be received during VoD transmission or live transmission.
+
+Syntax:
+
+**GET /URI?ac=xxxx&ts=5 HTTP/1.1**
+
+| Item   | M/O | Description                                                 |
+|--------|-----|-------------------------------------------------------------|
+| Method | M   | GET                                                         |
+| URI    | M   | URI obtained from the presentation description.             |
+|        | ac  | O Access Ticket obtained from the presentation description. |
+|        | ts  | M 5<br>This parameter shall exist if ac is contained.       |
+
+- For the file downloading, it is not necessary to send the abnormal termination request.
+- When the terminal receives the response to this request, the VoD/live transmission is finished. The response will be "200 OK" or similar, and the terminal should ignore it.
+
+## 6.5 Camera control
+
+This clause describes camera control functions. If the "camctl" attribute is specified in the presentation description, the terminal shall recognize the content as camera control enabled. The camera control is carried out in accordance with the following procedure:
+
+- request the camera control ticket;
+- retrieve the ticket;
+- send the camera control command;
+- receive the notification of completion;
+
+Details are defined in the following subclauses.
+
+### 6.5.1 Request of the camera control ticket
+
+The request of the camera control ticket is issued with the data transmission request. This is done by adding a header to the HTTP request. The following shows the format of the header.
+
+**x-up-devcap-streaming-camctl: get\_control**
+
+If the ticket is successfully retrieved, the following header will be embedded in the HTTP response of the data transmission.
+
+**x-streaming-camctl: XXX**
+
+where XXX is the period of validity in seconds of the camera control assigned to the terminal. The range of the XXX is 0 to 999.
+
+If the XXX is less than zero or if the header is not contained in the HTTP response, the camera control ticket request has been rejected by the server.
+
+The following shows an example of the request and the response with the camera control ticket retrieval.
+
+*(Request)*
+
+**GET /URI?data=evdo-4&ac=xxxx&br=128000&ts=3 HTTP/1.1**
+
+**Range:bytes=48000-144767**
+
+**x-up-devcap-streaming-camctl: get\_control**
+
+*(Response)*
+
+**HTTP/1.1 206 Partial Content**
+
+**Content-Range: bytes 48000-96000/1572864**
+
+**x-streaming-camctl: 30**
+
+Note that if the terminal receives the "x-streaming-camctl" header without sending the request of the camera control ticket, it shall be ignored.
+
+### 6.5.2 Send the camera control command
+
+The request of the camera control is issued with the data transmission request as well as the ticket request. This is done by adding a header to the HTTP request during the ticket validation period. The following shows the format of the header.
+
+x-up-devcap-streaming-camctl: pan $\pm$ X, tilt $\pm$ X, zoom $\pm$ X
+
+where X is relative camera position, which is an integer value from 0 to 5. Adaptation of the value to the actual camera position is outside the scope of this Recommendation. Only the supported parameter shall be sent. The supported parameter is specified by the "camctl" attribute in the presentation description. See 5.3.3. Parameters that are not changed do not have to be sent. In this case, making X to 0 is also accepted.
+
+If the control is successfully performed, the following header will be embedded in the HTTP response of the data transmission.
+
+x-streaming-campos: pan+3, tilt-1, zoom+2
+
+where each parameter is an actual camera position as a consequence of the camera control.
+
+The following shows an example of the request and the response with the camera control parameters.
+
+*(Request)*
+
+**GET /URI?data=evdo-4&ac=xxxx&br=128000&ts=3 HTTP/1.1**
+
+**Range:bytes=96000-192767**
+
+**x-up-devcap-streaming-camctl: pan+1,tilt-1,zoom+2**
+
+*(Response)*
+
+**HTTP/1.1 206 Partial Content**
+
+**Content-Range: bytes 96000-134000/1572864**
+
+**x-streaming-campos: pan+3,tilt+0,zoom+1**
+
+Note that if the terminal receives the "x-streaming-campos" header without sending the request of the camera control ticket, it shall be ignored. If the server receives the "x-up-devcap-streaming-camctl" parameter without a valid ticket, it shall be ignored. The terminal shall not re-send the "x-up-devcap-streaming-camctl" parameter unless the terminal receives the "x-streaming-campos" response.
+
+
+
+# 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                                                                                            |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b>                             |
+| 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 and general software aspects for telecommunication systems                                                           |
\ No newline at end of file
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@@ -0,0 +1,342 @@
+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.1301**
+
+(01/2021)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Cloud-based converged media services for IP and  
+broadcast cable television
+
+---
+
+**Specification of a cloud-based converged media  
+service to support Internet protocol and  
+broadcast cable television – Requirements**
+
+Recommendation ITU-T J.1301
+
+
+
+# Recommendation ITU-T J.1301
+
+# Specification of a cloud-based converged media service to support Internet protocol and broadcast cable television – Requirements
+
+## Summary
+
+Recommendation ITU-T J.1301 specifies functional requirements for a cloud-based converged media service (CBCMS) to support Internet protocol (IP) and broadcast cable television (TV). With the development of cloud-native technology, CBCMS can be quickly deployed by cable TV operators. This Recommendation forms part of a series and specifies requirements for function, architecture, interface and security for CBCMSs to support IP and broadcast cable TV.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T J.1301   | 2021-01-13 | 9           | <a href="http://handle.itu.int/11.1002/1000/14585">11.1002/1000/14585</a> |
+
+## Keywords
+
+CBCMS, converged media, requirements.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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 .....                           | 1    |
+| 3.1 Terms defined elsewhere .....             | 1    |
+| 3.2 Terms defined in this Recommendation..... | 1    |
+| 4 Abbreviations and acronyms .....            | 2    |
+| 5 Conventions .....                           | 2    |
+| 6 Overview .....                              | 3    |
+| 7 General requirements.....                   | 4    |
+| 7.1 Functional requirements .....             | 4    |
+| 7.2 Architecture requirements .....           | 5    |
+| 7.3 Interface requirements .....              | 5    |
+| 7.4 Security requirements .....               | 6    |
+| Bibliography.....                             | 7    |
+
+## **Introduction**
+
+This Recommendation is part 1 of a multi-part deliverable covering the requirements for cloud-based converged media service to support IP and broadcast cable TV, as identified below:
+
+## **Part 1: Requirements.**
+
+Part 2: System architecture.
+
+Part 3: System specification on collaboration between production media cloud and cable service cloud.
+
+# Recommendation ITU-T J.1301
+
+## Specification of a cloud-based converged media service to support Internet protocol and broadcast cable television – Requirements
+
+## 1 Scope
+
+This Recommendation specifies requirements for cloud-based converged media services (CBCMSs) to support Internet protocol (IP) and broadcast cable television (TV). The CBCMS is intended to be deployed in the service cloud of cable TV operators, which enables rapid innovation and deployment of new services, flexible expansion of online services, smart adaptation of service origins or paths to meet the distribution needs for different terminal types and network status.
+
+## 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 J.205] Recommendation ITU-T J.205 (2012), *Requirements for an application control framework using integrated broadcast and broadband digital television*.
+
+[ITU-T J.295] Recommendation ITU-T J.295 (2012), *Functional requirements for a hybrid cable set-top box*.
+
+## 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 infrastructure as a service (IaaS)** [b-ITU-T Y.3500]: Cloud service category in which the cloud capabilities type provided to the cloud service customer is an infrastructure capabilities type.
+
+**3.1.2 platform as a service (PaaS)** [b-ITU-T Y.3500]: Cloud service category in which the cloud capabilities type provided to the cloud service customer is a platform capabilities type.
+
+**3.1.3 software as a service (SaaS)** [b-ITU-T Y.3500]: Cloud service category in which the cloud capabilities type provided to the cloud service customer is an application capabilities type.
+
+**3.1.4 integrated broadcast and broadband (IBB) DTV service** [ITU-T J.205]: A service that simultaneously provides an integrated experience of broadcasting and interactivity relating to media content, data and applications from multiple sources, where the interactivity is sometimes associated with broadcasting programmes.
+
+### 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 cloud-based converged media service (CBCMS)**: A service intended for deployment by cable television operators and to support the requirements of rapid service innovation and deployment, which enables media services to be developed by separate vendors according to standard application programming interfaces, where appropriate.
+
+**3.2.2 microservice:** An architectural and organizational approach to software development where software is composed of small independent microservices that communicate over well-defined application programming interfaces. Microservice architecture makes applications easier to scale and faster to develop, enabling innovation and accelerating time-to-market for new features.
+
+**3.2.3 cloud digital video recorder (DVR):** A recorder that saves television (TV) shows in the cloud data centre of a service provider rather than in the DVR or set-top box near the TV. Cloud DVRs enable customers to store more content and record more shows that are broadcast at the same time.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|        |                                     |
+|--------|-------------------------------------|
+| AI     | Artificial Intelligence             |
+| API    | Application Programming Interface   |
+| CA     | Conditional Access                  |
+| CBCMS  | Cloud-Based Converged Media Service |
+| DevOps | Development and Operations          |
+| DRM    | Digital Rights Management           |
+| DTV    | Digital Television                  |
+| DVB    | Digital Video Broadcasting          |
+| DVR    | Digital Video Recorder              |
+| IaaS   | Infrastructure as a Service         |
+| IBB    | Integrated Broadcast and Broadband  |
+| PaaS   | Platform as a Service               |
+| PPV    | Pay Per View                        |
+| QAM    | Quadrature Amplitude Modulation     |
+| SaaS   | Software as a Service               |
+| TV     | Television                          |
+| VOD    | Video On Demand                     |
+
+## 5 Conventions
+
+In this Recommendation:
+
+The phrase "**is required to**" indicates a requirement that must be strictly followed and from which no deviation is permitted if conformity to this Recommendation is to be claimed.
+
+The phrase "**is recommended**" indicates a requirement that is recommended but which is not absolutely required. Thus this requirement need not be present to claim conformity.
+
+The phrase "**is prohibited from**" indicates a requirement that must be strictly followed and from which no deviation is permitted if conformity to this Recommendation is to be claimed.
+
+The phrase "**can optionally**" indicates an optional requirement that is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator or service
+
+provider. Rather, it means the vendor may optionally provide the feature and still claim conformity with this Recommendation.
+
+In the body of this Recommendation and its annexes, the words *shall*, *shall not*, *should*, and *may* sometimes appear, in which case they are to be interpreted, respectively, as *is required to*, *is prohibited from*, *is recommended*, and *can optionally*. The appearance of such phrases or keywords in an appendix or in material explicitly marked as *informative* are to be interpreted as having no normative intent.
+
+## 6 Overview
+
+CBCMS is a service that provides various capabilities according to practical development requirements, including service abstraction, encapsulation, registration, control and open methods of various services. CBCMS will be deployed by cable TV operators and is intended to support rapid service innovation and deployment of interoperable IP-based cable TV systems. The general architecture of CBCMS is depicted in Figure 1.
+
+![Figure 1 – Cloud-based converged media service general architecture diagram](7a0db9703b68b3d06cdaeefc084c0006_img.jpg)
+
+The diagram illustrates the general architecture of CBCMS, showing a stack of layers. At the top is a blue box labeled 'Service abilities encapsulation and aggregation'. Below this is the SaaS layer, which contains several boxes: 'Service ability 1', 'Service ability 2', 'Service ability 3', an ellipsis '...', and 'Service ability N'. To the right of these boxes is a bracket labeled 'SaaS'. Below the SaaS layer is the PaaS layer, represented by a blue box labeled 'Libraries of microservices'. To the right of this box is a bracket labeled 'PaaS'. Below the PaaS layer is the IaaS layer, which consists of two blue boxes: 'Resources configuration/control' and 'Resources assurance/monitoring'. To the right of these boxes is a bracket labeled 'IaaS'. At the bottom of the stack is a dashed box labeled 'Cloud platform'. The entire stack is labeled 'J.1301(21)\_F01' at the bottom right.
+
+Figure 1 – Cloud-based converged media service general architecture diagram
+
+**Figure 1 – Cloud-based converged media service general architecture**
+
+Based on the cloud platform, the CBCMS has three layers: IaaS, PaaS and SaaS.
+
+The IaaS layer is required to do system cloud orchestration, virtual and physical cloud resources configuration, and assurance.
+
+The PaaS layer is required to provide libraries of CBCMS microservices that implement the key building blocks to be used by CBCMS service abilities.
+
+The SaaS layer is required to be composed of various service abilities that comprise all aspects of the IP-based video service. The SaaS layer also includes service abilities encapsulation and aggregation, which provide a common application programming interface (API) for use by all IP-based video devices.
+
+The details of the standard microservices that comprise the PaaS layer and especially all TV services that are included within the SaaS are under study.
+
+## **7 General requirements**
+
+### **7.1 Functional requirements**
+
+This Recommendation includes IP and broadcast cable TV services known at the time of drafting; however, this Recommendation is a framework that allows new services to be easily added in the future.
+
+#### **7.1.1 Cable digital television service**
+
+A CBCMS is required to support playback of the content provided by broadcast digital television (DTV) services as specified in [ITU-T J.295]. See also [b-GB-SEP] and [b-ETSI EN 301 192].
+
+#### **7.1.2 Integrated broadcast and broadband digital television service**
+
+A CBCMS is required to support playback of the content provided by IBB DTV services as specified in [ITU-T J.205]. See also [b-ETSI TS 102 809].
+
+#### **7.1.3 Internet protocol linear and time-shifting service**
+
+A CBCMS is required to support live and time-shifting TV programming and other video content using the IP.
+
+#### **7.1.4 Video-on-demand service**
+
+A CBCMS is required to support playback of the content provided by IP-based video on demand (VOD) and pay-per-view (PPV) services as specified in [ITU-T J.295], and shall support playback of the content provided by IP VOD services based on quadrature amplitude modulation (QAM).
+
+#### **7.1.5 Cloud digital video recorder service**
+
+A CBCMS is required to support a cloud DVR that saves TV shows in the cloud data centre of a service provider rather than in the DVR or set-top box near the TV. Cloud DVRs enable customers to store more content and record more shows that are broadcast at the same time.
+
+#### **7.1.6 Service integration**
+
+A CBCMS is required to support media services, such as linear, time-shifting, VOD or cloud DVR, with various capabilities according to practical development requirements, including service abstraction, encapsulation, registration and control.
+
+#### **7.1.7 Service adaptation**
+
+A CBCMS is required to support service coordination and adaptation to meet distribution needs for different service scenarios (e.g., different terminal types and different network conditions), which allows users to consume content both by terminal devices connected to a digital video broadcasting (DVB) cable distribution network and by terminal devices via an IP network.
+
+#### **7.1.8 Media content integration**
+
+A CBCMS is required to support the integration and enhancement of media content resources from different platforms, such as self-media and social media, which provide original material for service innovation.
+
+#### **7.1.9 Media processing**
+
+A CBCMS is required to support a variety of media processing tools such as non-linear editing, video rendering, special effects production, and video and audio transcoding, to facilitate media content production, integration and service release.
+
+#### **7.1.10 Media artificial intelligence service**
+
+A CBCMS is recommended to support media artificial intelligence (AI) services, such as intelligent processing, identification, analysis and decision making, which enable video tags, video fingerprints, video search, content moderation, etc.
+
+#### **7.1.11 Operating support capabilities**
+
+A CBCMS is required to support unified authentication, identity management, authorization management, business management and other back-end support functionalities that enable rapid service deployment with an open capability engine.
+
+#### **7.1.12 Data integration and analysis**
+
+A CBCMS is required to support data integration and analysis of services, products, customers, markets, services, management, etc., which assist the service design, deployment, operation and decision-making process.
+
+#### **7.1.13 Security**
+
+A CBCMS is required to support security mechanisms, such as content encryption, digital rights management (DRM) and conditional access (CA) and comply with security requirements of systems deployed in the cloud. CBCMS is recommended to support multi-dimensional data analysis to strengthen security.
+
+#### **7.1.14 Scaling**
+
+A CBCMS is required to support secure auto-scaling and resource optimization. Each service scales independently.
+
+#### **7.1.15 Test environment**
+
+A CBCMS is recommended to support management systems, such as an application development test environment and developer community on an open platform.
+
+### **7.2 Architecture requirements**
+
+The deployment of CBCMS is required to refer to the cloud-native architecture designed as loosely coupled microservices, the resiliency core, lightweight orchestrated containers and agile development and operations (DevOps). Typically, it consists of five layers devoted to: application, ability, infrastructure, management and security.
+
+The application layer provides a high-level architecture listing all converged media services, corresponding functionalities and APIs which fulfil the aforementioned requirements.
+
+The ability layer provides the core capabilities of converged media services. It includes functions such as content aggregation, content processing, content distribution, load balancing, big data, AI and DevOps support.
+
+The infrastructure layer is required to support elastic computing, storage, network and security sources, which are able to be quickly expanded or decreased to meet changing demand.
+
+The management layer is composed of a series of components, which is required to register and orchestrate microservices, and manage basic functions and other components for the whole architecture.
+
+The security layer is required to comply with clause 7.4.
+
+### **7.3 Interface requirements**
+
+To provide ease of service development and extension, CBCMS is required to include APIs and capability interfaces. CBCMS APIs are used to provide a common application environment for the
+
+implementation of various services. CBCMS capability interfaces are used to expand microservice capabilities. Protocols used for APIs are required to be lightweight.
+
+### **7.4 Security requirements**
+
+CBCMS security is required to provide the following security aspects: security architecture, fundamental security capabilities and basic functionalities.
+
+CBCMS security architecture should determine how CBCMS fundamental security capabilities can be built and expanded based on the CBCMS software architecture and security mechanism.
+
+CBCMS fundamental security capabilities shall include hardware security, software security, network security and data security. The hardware security capability shall include a secure storage area.
+
+CBCMS basic functionalities shall include content security, service security and payment security. CBCMS basic functionalities shall also include a secure upgrade. CBCMS basic functionalities shall be able to continuously be enhanced and expanded through the improvement of fundamental capabilities and addition of more secure functional components.
+
+## Bibliography
+
+- [b-ITU-T Y.3500] Recommendation ITU-T Y.3500 (2014), *Information technology – Cloud computing – Overview and vocabulary*.
+- [b-ETSI EN 301 192] European Standard ETSI EN 301 192 V1.6.1 (2015), *Digital video broadcasting (DVB); DVB specification for data broadcasting*.
+- [b-ETSI TS 102 809] Technical Specification ETSI TS 102 809 V1.3.1 (2017), *Digital video broadcasting (DVB); Signalling and carriage of interactive applications and services in hybrid broadcast/broadband environments*.
+- [b-GB-SEP] GB/T 28160-2011, 数字电视广播电子节目指南规范 [Specification of electronic programme guide for digital television broadcasting].
+
+
+
+
+
+## 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                                                                                                                       |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b>                                                        |
+| 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
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+
+
+# Recommendation
+
+## **ITU-T J.1311 (06/2024)**
+
+SERIES J: Cable networks and transmission of television, sound programme and other multimedia signals
+
+Cloud-based services for IP delivery over integrated broadband cable network
+
+## --- **Technical requirements for cloud gaming service platforms**
+
+![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 grid lines and the letters 'ITU' in a bold, blue, sans-serif font.
+
+ITU logo
+
+## ITU-T J-SERIES RECOMMENDATIONS
+
+# **Cable networks and transmission of television, sound programme and other multimedia signals**
+
+|                                                                                                 |                      |
+|-------------------------------------------------------------------------------------------------|----------------------|
+| GENERAL RECOMMENDATIONS                                                                         | J.1-J.9              |
+| GENERAL SPECIFICATIONS FOR ANALOGUE SOUND-PROGRAMME TRANSMISSION                                | J.10-J.19            |
+| PERFORMANCE CHARACTERISTICS OF ANALOGUE SOUND-PROGRAMME CIRCUITS                                | J.20-J.29            |
+| EQUIPMENT AND LINES USED FOR ANALOGUE SOUND-PROGRAMME CIRCUITS                                  | J.30-J.39            |
+| DIGITAL ENCODERS FOR ANALOGUE SOUND-PROGRAMME SIGNALS - PART 1                                  | J.40-J.49            |
+| DIGITAL TRANSMISSION OF SOUND-PROGRAMME SIGNALS                                                 | J.50-J.59            |
+| CIRCUITS FOR ANALOGUE TELEVISION TRANSMISSION                                                   | J.60-J.69            |
+| ANALOGUE TELEVISION TRANSMISSION OVER METALLIC LINES AND INTERCONNECTION WITH RADIO-RELAY LINKS | J.70-J.79            |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS                                                      | J.80-J.89            |
+| ANCILLARY DIGITAL SERVICES FOR TELEVISION TRANSMISSION                                          | J.90-J.99            |
+| OPERATIONAL REQUIREMENTS AND METHODS FOR TELEVISION TRANSMISSION                                | J.100-J.109          |
+| INTERACTIVE SYSTEMS FOR DIGITAL TELEVISION DISTRIBUTION (DOCSIS FIRST AND SECOND GENERATIONS)   | J.110-J.129          |
+| TRANSPORT OF MPEG-2 SIGNALS ON PACKETIZED NETWORKS                                              | J.130-J.139          |
+| MEASUREMENT OF THE QUALITY OF SERVICE - PART 1                                                  | J.140-J.149          |
+| DIGITAL TELEVISION DISTRIBUTION THROUGH LOCAL SUBSCRIBER NETWORKS                               | J.150-J.159          |
+| IPCABLECOM (MGCP-BASED) - PART 1                                                                | J.160-J.179          |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS - PART 1                                             | J.180-J.189          |
+| CABLE MODEMS AND HOME NETWORKING                                                                | J.190-J.199          |
+| APPLICATION FOR INTERACTIVE DIGITAL TELEVISION - PART 1                                         | J.200-J.209          |
+| INTERACTIVE SYSTEMS FOR DIGITAL TELEVISION DISTRIBUTION (DOCSIS THIRD TO FIFTH GENERATIONS)     | J.210-J.229          |
+| MULTI-DEVICE SYSTEMS FOR CABLE TELEVISION                                                       | J.230-J.239          |
+| MEASUREMENT OF THE QUALITY OF SERVICE - PART 2                                                  | J.240-J.249          |
+| DIGITAL TELEVISION DISTRIBUTION THROUGH LOCAL SUBSCRIBER NETWORKS                               | J.250-J.259          |
+| IPCABLECOM (MGCP-BASED) - PART 2                                                                | J.260-J.279          |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS - PART 2                                             | J.280-J.289          |
+| CABLE SET-TOP BOX                                                                               | J.290-J.299          |
+| APPLICATION FOR INTERACTIVE DIGITAL TELEVISION - PART 2                                         | J.300-J.309          |
+| MEASUREMENT OF THE QUALITY OF SERVICE - PART 3                                                  | J.340-J.349          |
+| IPCABLECOM2 (SIP-BASED) - PART 1                                                                | J.360-J.379          |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS - PART 3                                             | J.380-J.389          |
+| MEASUREMENT OF THE QUALITY OF SERVICE - PART 4                                                  | J.440-J.449          |
+| IPCABLECOM2 (SIP-BASED) - PART 2                                                                | J.460-J.479          |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS - PART 4                                             | J.480-J.489          |
+| TRANSPORT OF LARGE SCREEN DIGITAL IMAGERY                                                       | J.600-J.699          |
+| SECONDARY DISTRIBUTION OF IPTV SERVICES                                                         | J.700-J.799          |
+| MULTIMEDIA OVER IP IN CABLE                                                                     | J.800-J.899          |
+| TRANSMISSION OF 3-D TV SERVICES                                                                 | J.900-J.999          |
+| CONDITIONAL ACCESS AND PROTECTION                                                               | J.1000-J.1099        |
+| SWITCHED DIGITAL VIDEO OVER CABLE NETWORKS                                                      | J.1100-J.1119        |
+| SMART TV OPERATING SYSTEM                                                                       | J.1200-J.1209        |
+| IP VIDEO BROADCAST                                                                              | J.1210-J.1219        |
+| CABLE SET-TOP BOX - PART 2                                                                      | J.1290-J.1299        |
+| CLOUD-BASED CONVERGED MEDIA SERVICES FOR IP AND BROADCAST CABLE TELEVISION                      | J.1300-J.1309        |
+| <b>CLOUD-BASED SERVICES FOR IP DELIVERY OVER INTEGRATED BROADBAND CABLE NETWORK</b>             | <b>J.1310-J.1319</b> |
+| TELEVISION TRANSPORT NETWORK AND SYSTEM DEPLOYMENT IN DEVELOPING COUNTRIES                      | J.1400-J.1409        |
+| ARTIFICIAL INTELLIGENCE (AI) ASSISTED CABLE NETWORKS                                            | J.1600-J.1649        |
+
+For further details, please refer to the list of ITU-T Recommendations.
+
+# Recommendation ITU-T J.1311
+
+## Technical requirements for cloud gaming service platforms
+
+## Summary
+
+Recommendation ITU-T J.1311 describes the cloud gaming service platform basic components and functional element requirements including resource layer, capability layer, business layer and client access layer.
+
+This Recommendation is intended to provide a reference for game service developers and operators to build and operate a cloud gaming service.
+
+## History\*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T J.1311   | 2024-06-29 | 9           | 11.1002/1000/15971 |
+
+## Keywords
+
+Cloud gaming, requirements, service platform.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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 .....                                   | 1    |
+| 3.1 Terms defined elsewhere .....                     | 1    |
+| 3.2 Terms defined in this Recommendation.....         | 1    |
+| 4 Abbreviations and acronyms .....                    | 1    |
+| 5 Conventions .....                                   | 1    |
+| 6 Cloud gaming service platform basic components..... | 2    |
+| 6.1 Resource layer .....                              | 2    |
+| 6.2 Capability layer .....                            | 2    |
+| 6.3 Business layer.....                               | 3    |
+| 6.4 Client access layer .....                         | 3    |
+| Bibliography.....                                     | 4    |
+
+
+
+# Recommendation ITU-T J.1311
+
+## Technical requirements for cloud gaming service platforms
+
+# 1 Scope
+
+This Recommendation mainly specifies the basic components and required functional elements of cloud gaming service platforms for cable network operators, and presents the corresponding technical requirements for each layer of cloud gaming service platforms.
+
+## 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.
+
+None.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following term defined elsewhere:
+
+**3.1.1 cloud gaming** [b-ITU-T F.743.17]: A way of playing the game on a cloud server. In the "cloud gaming" mode, game storage, computing, rendering, and so on are completed in the cloud, players can experience high-quality games through any terminal, anytime anywhere.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following term:
+
+**3.2.1 game instance**: An independent virtual computing environment provided to users in the cloud that can run games.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|     |                          |
+|-----|--------------------------|
+| CPU | Central Processing Unit  |
+| GPU | Graphics Processing Unit |
+| IDC | Internet Data Centre     |
+| SDK | Software Development Kit |
+
+# 5 Conventions
+
+In this Recommendation:
+
+The phrase "**is required to**" indicates a requirement that must be strictly followed and from which no deviation is permitted if conformity with this document is to be claimed.
+
+The phrase "**is recommended**" indicates a requirement that is recommended but which is not absolutely required. Thus, this requirement needs not be present to claim conformity.
+
+The phrase "**is prohibited from**" indicates a requirement that must be strictly followed and from which no deviation is permitted if conformity with this document is to be claimed.
+
+The phrase "**can optionally**" indicates an optional requirement that is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformity with this Recommendation.
+
+In this Recommendation the words *shall*, *shall not*, *should*, and *may* sometimes appear, in which case they are to be interpreted, respectively, as *is required to*, *is prohibited from*, *is recommended*, and *can optionally*. The appearance of such phrases or keywords in an appendix or in material explicitly marked as *informative* are to be interpreted as having no normative intent.
+
+# 6 Cloud gaming service platform basic components
+
+The cloud gaming service platform includes resource layer, capability layer, business layer and client access layer.
+
+![Diagram of Cloud gaming service platform architecture showing four layers: Business layer, Client access layer, Capability layer, and Resource layer.](5860ad6bd2a2dd8d1ab12864b8f90f37_img.jpg)
+
+The diagram illustrates the architecture of a cloud gaming service platform. It consists of four layers arranged vertically. The top layer is divided into two side-by-side boxes labeled "Business layer" and "Client access layer". Below this top layer is a single box labeled "Capability layer". At the bottom is another single box labeled "Resource layer". The layers are stacked, with the "Business layer" and "Client access layer" on top of the "Capability layer", which is on top of the "Resource layer".
+
+J.1311(24)
+
+Diagram of Cloud gaming service platform architecture showing four layers: Business layer, Client access layer, Capability layer, and Resource layer.
+
+**Figure 1 – Cloud gaming service platform architecture**
+
+## 6.1 Resource layer
+
+The resource layer is equipped with basic capabilities such as configuration, management, monitoring and automated fault handling of data centres and network resources. It provides support for large-scale distributed systems and serves as an interface for the capability layer, supporting the configuration and scheduling of basic resources for the capability layer. The basic capabilities required for the resource layer of cloud gaming include:
+
+[CGSP-01] Game instance device is required to have powerful, flexibly allocatable rendering capabilities based on dedicated graphics processors (graphics processing units (GPUs)).
+
+[CGSP-02] Game instance device is required to have efficient video hardware encoding capabilities.
+
+[CGSP-03] Both game instance device and Internet data centre (IDC) are required to have large-capacity downstream network bandwidth.
+
+[CGSP-04] Game instance device is required to support virtualization technology to virtualize central processing unit (CPU) and GPU, enabling flexible adjustment of CPU and GPU resources allocated to individual instances.
+
+## 6.2 Capability layer
+
+The capability layer provides configuration, management, monitoring and fault handling capabilities for application resources, user resources, running instances, intermediate processes and bidirectional data flows between instances and terminals, and provides service interfaces for the business layer.
+
+[CGSP-05] The cloud gaming capability layer is required to have game instance management capabilities, mainly including adding instances, identifying instances, configuring instances, instance upgrades and instance allocation.
+
+[CGSP-06] The capability to put games on the shelf is required to include acquiring game packages, storing them and configuring games within the system.
+
+[CGSP-07] The cloud gaming service platform is required to have the ability to adjust audio and video streaming metrics for different scenarios.
+
+[CGSP-08] The cloud gaming service platform is required to detect network fluctuations and take automatic response measures.
+
+[CGSP-09] The cloud gaming service platform is required to support game operations by users on different terminals.
+
+## **6.3 Business layer**
+
+The business layer refers to the platform that provides customers with customized cloud gaming business capabilities and management.
+
+[CGSP-10] The business layer is required to provide functional interfaces for service subscription and unsubscription, supporting customers to subscribe to or unsubscribe from specific services, or to decrease or increase the number of subscriptions.
+
+[CGSP-11] The business layer is required to provide interfaces for game on/off shelf and cloud gaming parameter configuration.
+
+[CGSP-12] Instruction compatibility configuration is required to mapping user input operations to game instructions through configuration.
+
+[CGSP-13] The business layer is required provide pricing and billing functions to support accounting and charging for various cloud gaming services.
+
+## **6.4 Client access layer**
+
+The cloud gaming service platform needs to provide software development kits (SDKs) that support access to various types of terminals (common terminals include portable terminals, computers and television sets) to assist customers in accessing cloud gaming.
+
+[CGSP-14] Before accessing the global navigation service, it is required to perform user identity verification on the client side to verify the legitimacy of user requests and prevent malicious requests from occupying service resources.
+
+[CGSP-15] The access layer is required to collect input instructions from terminal devices to support game operations and transmit these input instructions to the capability layer through the instruction transmission service provided by the capability layer.
+
+[CGSP-16] The access layer is required to upload the above information to the cloud gaming service platform.
+
+## Bibliography
+
+[b-ITU-T F.743.17] Recommendation ITU-T F.743.17 (2022), *Requirements for cloud gaming 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                                                                                                                       |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b>                                                        |
+| 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
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+
+
+![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**
+
+**J.14**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**TELEVISION AND SOUND TRANSMISSION**
+
+---
+
+**RELATIVE LEVELS AND IMPEDANCES ON  
+AN INTERNATIONAL SOUND - PROGRAMME  
+CONNECTION**
+
+**ITU-T Recommendation J.14**
+
+(Extract from the *Blue Book*)
+
+---
+
+# NOTES
+
+1 ITU-T Recommendation J.14 was published in Fascicle III.6 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.
+
+## **RELATIVE LEVELS AND IMPEDANCES ON AN INTERNATIONAL SOUND-PROGRAMME CONNECTION**
+
+*(former Recommendation J.13; amended at Geneva, 1972, 1976 and 1980, and at Melbourne, 1988)*
+
+### **1 Level adjustment on an international sound-programme connection**
+
+The CCITT recommends the use of the *constant voltage* method. If, to a zero relative level point of the international sound-programme connection, a zero absolute voltage level is applied (sine-wave signal of 0.775 volts r.m.s.) at the reference frequency 0.8 or 1 kHz, the absolute voltage level at the output of each sound-programme circuit (Points B, C, D . . . F of Figure 3/J.13) should be + 6 dB (i.e. 1.55 volts r.m.s.). Therefore these points have to be regarded as relative level points of + 6 dBrs according to Recommendations J.21, J.22 and J.23.
+
+The zero relative level point is, in principle, the origin of the international sound-programme connection (Point A in Figure 3/J.13). Different conventions may be agreed between the telephone Administration and the broadcast organization within a country, provided that the levels on the international sound-programme link are unchanged.
+
+A zero relative level point is, in principle, a point at which the sound-programme signals correspond exactly with those at the origin of the international sound-programme connection. At a point of zero relative levels, signals have been controlled in level by the broadcasting organization such that the peak levels very rarely exceed +9 dB relative to the peak values reached by a sine-wave signal of 0.775 volts r.m.s. (for a 600-ohm resistor load, when levels are expressed in terms of dBm).
+
+In Recommendation 645, CCIR has defined test signals to be used on international sound-programme connections based on existing CCITT Recommendations.
+
+## **2 Diagram of signal levels on an international sound-programme connection**
+
+All signal levels are expressed in terms of r.m.s. values of sine-wave signals with reference to 0.775 volts.
+
+The voltage level diagram for an international sound-programme connection, however made up, should be such that the voltage levels shown will not exceed the maximum undistorted power which an amplifier can deliver to a sound-programme link when a peak voltage (i.e. +9 dB) is applied to a zero relative level point on the international sound-programme connection.
+
+With these conditions, +6 dB is the nominal voltage level at the output of the terminal amplifiers of the sound-programme circuits making up the international sound-programme link (Points B, C, D . . . F of Figure 3/J.13).
+
+Considering that rare excursions of the permitted maximum signal level may occur, and that adjustment errors and maintenance tolerance have to be taken into account, sound-programme circuits need a definite overload margin. The amount of this margin is still under study.
+
+If a sound-programme circuit which is part of the international sound-programme link is set up on a group in a carrier system, the objective for a new design of equipment is that the relative level of the sound-programme circuit, with respect to the relative level of the telephone channel, should be chosen such that the mean value and the peak value of the load presented by the sound-programme channel should be no higher than that of the telephone channels which are replaced by the sound-programme channel. The effects of pre-emphasis and compandors should, where present, be taken into consideration.
+
+It is recognized that this condition may not be observed in all cases, particularly in certain existing types of equipments. It is recommended that in those cases the zero relative level points of the sound-programme circuit and of the telephone channels should coincide.
+
+It might be as well, however, if the equipment could, where possible, tolerate a maximum difference of  $\pm 3$  dB between the relative levels of the sound-programme and telephone transmissions, so that the best adjustment can be obtained, depending on any noise or intermodulation present, but at the same time observing the constraints imposed by the considerations on loading.
+
+*Note* – The relative level at which the modulated sound-programme signal is applied to the group link is given in Recommendations J.31 for 15 kHz-type circuits, J.34 for 7 kHz-type circuits and in the Annex to Recommendation J.22 for 10 kHz-type circuits.
+
+### 3 Definitions and abbreviations for new sound-programme signals
+
+Definitions and symbols are in current use to define relative levels for telephony. However, additional definitions and symbols are necessary for the absolute and relative levels in respect of sound-programme signals. The corresponding definitions and symbols for telephony and sound-programme signals are given below.
+
+#### 3.1 **dBm0<sup>1)</sup>**
+
+The absolute signal power level, in decibels, referred to a point of zero relative level.
+
+#### 3.2 **dB<sup>1)</sup>**
+
+The relative power level, in decibels.
+
+#### 3.3 **dBm0s**
+
+The absolute signal power level, in decibels, referred to a point of zero relative sound-programme level.
+
+#### 3.4 **dBrs**
+
+The relative (power) level, in decibels, with respect to sound- programme signals. (This abbreviation is only applicable at points in a sound-programme circuit where the signals can nominally be related to the input by a simple scaling factor.)
+
+*Note* – The use of level definitions is given in CCIR Recommendation 574.
+
+---
+
+1) These symbols traditionally relate to telephony relative levels.
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+
+
+![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
+
+**J.151**
+
+(10/2000)
+
+SERIES J: TRANSMISSION OF TELEVISION, SOUND  
+PROGRAMME AND OTHER MULTIMEDIA SIGNALS
+
+Digital television distribution through local subscriber  
+networks
+
+---
+
+**RF remodulator interface for digital television**
+
+ITU-T Recommendation J.151
+
+(Formerly CCITT Recommendation)
+
+---
+
+# ITU-T J-SERIES RECOMMENDATIONS
+
+# TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS
+
+|                                                                                                 |                    |
+|-------------------------------------------------------------------------------------------------|--------------------|
+| General Recommendations                                                                         | J.1–J.9            |
+| General specifications for analogue sound-programme transmission                                | J.10–J.19          |
+| Performance characteristics of analogue sound-programme circuits                                | J.20–J.29          |
+| Equipment and lines used for analogue sound-programme circuits                                  | J.30–J.39          |
+| Digital encoders for analogue sound-programme signals                                           | J.40–J.49          |
+| Digital transmission of sound-programme signals                                                 | J.50–J.59          |
+| Circuits for analogue television transmission                                                   | J.60–J.69          |
+| Analogue television transmission over metallic lines and interconnection with radio-relay links | J.70–J.79          |
+| Digital transmission of television signals                                                      | J.80–J.89          |
+| Ancillary digital services for television transmission                                          | J.90–J.99          |
+| Operational requirements and methods for television transmission                                | J.100–J.109        |
+| Interactive systems for digital television distribution                                         | J.110–J.129        |
+| Transport of MPEG-2 signals on packetised networks                                              | J.130–J.139        |
+| Measurement of the quality of service                                                           | J.140–J.149        |
+| <b>Digital television distribution through local subscriber networks</b>                        | <b>J.150–J.159</b> |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# **RF remodulator interface for digital television**
+
+## **Summary**
+
+With the advent of digital television (DTV) there is now a need for a simple and cost-effective interconnect between the various digital signal sources and the DTV receiver. Digital video and audio are now available from digital VCRs (DVCR), terrestrial broadcasts, digital video disks (DVD), cable TV, satellite systems and digital camcorders. The RF remodulator in this Recommendation is an economical and practical digital interconnect for the new consumer digital video devices. The RF remodulator, is a one way throughput device with a data rate of 19.3 Mbit/s, which is suitable for most connections. The interface transmits MPEG (Moving Picture Experts Group) data for compressed digital video and audio and an OSD (on-screen display) overlay. The RF remodulator uses a simple coaxial cable to interconnect devices in a way with which consumers are most familiar.
+
+## **Source**
+
+ITU-T Recommendation J.151 was prepared by ITU-T Study Group 9 (1997-2000) and approved by the World Telecommunication Standardization Assembly (Montreal, 27 September – 6 October 2000).
+
+## 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     | Scope.....                                                          | 1    |
+| 2     | Normative references .....                                          | 1    |
+| 3     | Abbreviations.....                                                  | 1    |
+| 4     | System overview .....                                               | 3    |
+| 5     | DTV remodulator RF output specifications.....                       | 5    |
+| 5.1   | Selectable output channel frequency.....                            | 5    |
+| 5.2   | Nominal RMS output level .....                                      | 5    |
+| 5.3   | Pilot phase noise .....                                             | 5    |
+| 5.3.1 | Pilot phase noise – 8 VSB trellis .....                             | 5    |
+| 5.3.2 | Pilot phase noise – 16 VSB .....                                    | 5    |
+| 5.4   | Error vector magnitude (EVM).....                                   | 5    |
+| 5.4.1 | EVM – 8 VSB trellis .....                                           | 5    |
+| 5.4.2 | EVM – 16 VSB.....                                                   | 5    |
+| 5.4.3 | EVM definition.....                                                 | 5    |
+| 5.5   | Connector.....                                                      | 6    |
+| 5.6   | Side-band output .....                                              | 6    |
+| 5.7   | Roll-off specification .....                                        | 6    |
+| 5.8   | Data and clock rates .....                                          | 7    |
+| 6     | On-screen display (OSD) support .....                               | 7    |
+| 6.1   | OSD encapsulation .....                                             | 7    |
+| 6.1.1 | PES encapsulation .....                                             | 8    |
+| 6.1.2 | Syntax and semantics for PES packets carrying OSD information ..... | 8    |
+| 6.1.3 | Maximum transmission rate for OSD data .....                        | 9    |
+| 6.1.4 | OSD retransmission.....                                             | 10   |
+| 7     | OSD data.....                                                       | 10   |
+| 7.1   | Format of OSD data .....                                            | 10   |
+| 7.1.1 | Subframe types .....                                                | 10   |
+| 7.1.2 | Subframe typeCode .....                                             | 11   |
+| 7.1.3 | Subframe processing.....                                            | 11   |
+| 7.1.4 | Subframe syntax and definition .....                                | 11   |
+| 7.2   | Alignment of OSD with video .....                                   | 19   |
+| 8     | Capability profiles.....                                            | 20   |
+| 9     | DTV RF remodulator input specifications.....                        | 20   |
+| 9.1   | Input overview .....                                                | 20   |
+
+|      | <b>Page</b>                               |
+|------|-------------------------------------------|
+| 9.2  | Input from remodulator to source ..... 21 |
+| 9.3  | Input from source to remodulator ..... 21 |
+| 10   | Monitor mode ..... 22                     |
+| 10.1 | Monitor mode overview..... 22             |
+| 10.2 | Monitor mode conditions..... 22           |
+| 10.3 | Monitor mode practices ..... 23           |
+| 11   | Measurement..... 24                       |
+
+# **RF remodulator interface for digital television**
+
+# **1 Scope**
+
+This ITU-T Recommendation defines an RF remodulator interface for digital television with an advanced on-screen display (OSD) overlay capability. This Recommendation defines minimum specifications for a one-way data path utilizing an 8 VSB trellis (8T VSB) or a 16 VSB remodulator in compliance with Annex D/J.83 (System D) (ATSC Standard A/53, Annex D). The advanced overlay uses the same OSD syntax as ITU-T J.117 and allows signal service providers their incremental revenue from programme guides and supplemental services. The RF remodulator also facilitates conditional access required by service providers.
+
+This Recommendation applies to any type of device used to connect to a J.83 System D compliant digital television receiver. Devices meeting this Recommendation should interoperate with any J.83 System D compliant receiver that also supports "monitor mode."
+
+This Recommendation addresses RF output specifications, on-screen display (OSD) capabilities, and capability profiles for a DTV remodulator and recommendations concerning input to the remodulator.
+
+This Recommendation is derived from several standards of the Electronic Industries Alliance (EIA).
+
+# **2 Normative 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 published regularly.
+
+- ITU-R BT.601-5 (1995), *Studio encoding parameters of digital television for standard 4:3 and wide-screen 16:9 aspect ratios.*
+- ITU-R BT.709-4 (2000), *Parameter values for the HDTV standards for production and international programme exchange.*
+- ITU-T J.83 (1997), *Digital multi-programme systems for television, sound and data services for cable distribution, Annex D.*
+- IEC 60169-24 (1991), *Radio-frequency connectors – Part 24: Radio-frequency coaxial connectors with screw coupling, typically for use in 75 ohm cable distribution systems (Type F).*
+
+# **3 Abbreviations**
+
+This Recommendation uses the following abbreviations:
+
+ATSC Advanced Television Systems Committee
+
+A/V Audio/Video
+
+CEA Consumer Electronics Association
+
+CLUT Colour Look-Up Table  
+CPU Central Processing Unit  
+CVCT Cable Virtual Channel Table  
+D/A Digital-to-Analogue  
+DTV Digital Television: ATSC compliant receiving device  
+DVCR Digital Video Cassette Recorder  
+DVD Digital Video Disk  
+EIA Electronic Industries Alliance  
+EIT Event Information Table  
+EVM Error Vector Magnitude  
+HDTV High Definition TeleVision  
+IEC International Electrotechnical Commission  
+IEEE Institute of Electrical and Electronics Engineers  
+IF Intermediate Frequency  
+IRC Interface Reference Clock  
+ITU International Telecommunication Union  
+MPEG Moving Picture Experts Group  
+NTSC National Television Systems Committee  
+OSD On-Screen Display  
+PAT Program Association Table  
+PES Program Elementary Stream  
+PID Program Identifier  
+PMT Program Map Table  
+PSIP Program and System Information Protocol  
+RF Radio Frequency  
+SDTV Standard Definition Television  
+STB Set-Top Box  
+TSID Transport Stream Identification  
+TVCT Terrestrial Virtual Channel Table  
+UHF Ultra High Frequency  
+VCR Video Cassette Recorder  
+VCT Virtual Channel Table  
+VHF Very High Frequency  
+VSB Vestigial SideBand
+
+# 4 System overview
+
+A typical NTSC analogue system with an RF remodulator appears in Figure 1. The figure shows a typical VCR block diagram but could be a cable set top box (STB) or satellite receiver. The consumer connects the RF signal from the antenna or cable feed to the VCR or STB. The VCR or other receiving device connects to the television receiver via the RF output jack. If the VCR or receiving device is not in use, it simply passes the entire RF spectrum through to the TV. If the VCR or receiving device is active in the play mode, it remodulates the video and audio signals to an unused RF channel for display by the television set. The VCR, STB or satellite receiver can overlay its own on-screen display for user control or added features. The connection is made with an inexpensive coaxial cable.
+
+![Block diagram of a typical NTSC system showing signal flow from antenna and cable feed through a splitter, tuner, overlay, RF remodulator, and RF switch to a TV. It also includes a CPU, menu system, and remote control.](562f471e8153729557e6a4ee6343c32c_img.jpg)
+
+```
+graph TD; Antenna --> Splitter; CableFeed[Cable Feed] --> Splitter; Splitter -- RF Pass Through --> RFSwitch[RF Switch]; Splitter --> Tuner[Tuner/IF or Tape Source]; Tuner -- Composite Video --> Overlay; Tuner --> CPU; MenuConst[Menu Const.] --> BitBuffer[Bit Buffer]; BitBuffer --> NTSC[NTSC Encoder]; NTSC --> Overlay; MenuFonts[Menu Fonts] --> MenuConst; CPU --> MenuConst; CPU --> BitBuffer; CPU --> MenuFonts; CPU --> Remote[Remote]; Overlay --> RFRemod[RF Remod]; RFRemod --> RFSwitch; RFSwitch -- RF to TV --> TV[TV];
+```
+
+The diagram illustrates the signal flow in a typical NTSC system. It starts with an 'Antenna' and 'Cable Feed' entering a 'Splitter'. The 'Splitter' has two outputs: 'RF Pass Through' which goes to an 'RF Switch', and a signal that goes to a 'Tuner/IF or Tape Source'. The 'Tuner/IF or Tape Source' outputs 'Composite Video' to an 'Overlay' block and also connects to a 'CPU'. The 'CPU' is connected to a 'Menu Const.' block, which in turn connects to a 'Bit Buffer' and then to an 'NTSC Encoder'. The 'NTSC Encoder' outputs to the 'Overlay' block. The 'CPU' also connects to 'Menu Fonts' and a 'Remote' control. The 'Overlay' block receives signals from the 'Tuner/IF or Tape Source' and the 'NTSC Encoder' and outputs to an 'RF Remod' block. The 'RF Remod' block outputs to the 'RF Switch'. The 'RF Switch' receives the 'RF Pass Through' signal and the output from the 'RF Remod' block and outputs 'RF to TV'.
+
+Block diagram of a typical NTSC system showing signal flow from antenna and cable feed through a splitter, tuner, overlay, RF remodulator, and RF switch to a TV. It also includes a CPU, menu system, and remote control.
+
+Figure 1/J.151 – Typical NTSC system
+
+The system of Figure 1 can be extended to the digital receiving device and digital TV receiver (DTV) by using the RF Remodulator as depicted in Figure 2. This Recommendation defines a specification for an RF digital interface to a DTV receiver that provides a level of functionality that is similar to the analogue system. This solution is very practical, cost-effective, and introduces no picture or sound degradation. The RF Remodulator has the added advantage of no cable length limitation as do some baseband digital interfaces such as the type in ITU-T J.117.
+
+![Block diagram of an Equivalent DTV system showing signal flow from various sources through a remodulator and coax cable to a digital TV receiver.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg)
+
+The diagram illustrates the signal flow in an equivalent DTV system. It is divided into two main sections: the source side (left) and the digital TV receiver side (right), connected by a coaxial cable.
+
+**Source Side (Left):**
+
+- An **Analogue A/V Source** (dashed box) connects to an **Overlay** (dashed box).
+- A **Resident or Downloaded Application** connects to an **OSD Gen.** (On-Screen Display Generator).
+- The **OSD Gen.** connects to a **Mux.** (Multiplexer).
+- An **ATSC Transport Stream Source** (labeled **MPEG-2**) also connects to the **Mux.**
+- The **Mux.** output connects to a **16 VSB RF Remod.** (Remodulator).
+- An optional **D/A** (Digital-to-Analog) converter connects the **ATSC Transport Stream Source** to the **Overlay**.
+- An optional **Analogue A/V** (oval) interface connects the **Overlay** to the **Compositor/Format Conversion** block in the receiver.
+
+The entire source section is labeled **Cable, Terrestrial, DVCR, Satellite or DVD Source**.
+
+**Transmission:**
+
+- The **16 VSB RF Remod.** output connects to the **Digital TV Receiver** via an **Antenna Terminal** and a **Coax Cable**.
+
+**Digital TV Receiver Side (Right):**
+
+- The **Coax Cable** input connects to a **16 VSB RF Demod.** (Demodulator).
+- The **16 VSB RF Demod.** output connects to a **Demux.** (Demultiplexer).
+- The **Demux.** output connects to an **SDTV & HDTV MPEG Decode** block.
+- The **SDTV & HDTV MPEG Decode** block connects to **Audio Processing** and **Compositor/Format Conversion**.
+- The **Compositor/Format Conversion** block also receives input from the optional **Analogue A/V** interface and connects to the **Display**.
+- An **OSD Interpreter** block is connected between the **Demux.** and the **Compositor/Format Conversion**.
+
+The entire receiver section is labeled **Digital TV Receiver**. A small code **T0909450-00** is present in the bottom right corner.
+
+Block diagram of an Equivalent DTV system showing signal flow from various sources through a remodulator and coax cable to a digital TV receiver.
+
+----- Support for the analogue interface is optional
+
+**Figure 2/J.151 – Equivalent DTV system**
+
+Figure 2 depicts a digital audio/video receiving device connected to a DTV receiver with a 75-ohm coaxial cable. The figure also shows an optional analogue baseband connection. The OSD data is multiplexed with the source material before the remodulator. This allows for extended features like on-screen programming guides or on-screen display capability for operating the VCR, STB or other signal-receiving device. If no OSD information is required, this system can deliver two HD signals to the DTV receiver using the 16VSB mode.
+
+Users of this Recommendation should note that future copy protection systems or standards will be implemented and content traversing this DTV RF interface will be required to comply with these future systems or standards.
+
+# **5 DTV remodulator RF output specifications**
+
+The entire transport modulation system should be compliant with Annex D/J.83, System D.
+
+## **5.1 Selectable output channel frequency**
+
+The channel output frequency is user selectable to one of two adjacent VHF or UHF channels. The system designer should choose output channels appropriate for the market or country where the product will be implemented. In addition, the channel frequency tolerance should be  $\pm 10$  kHz. All devices equipped with RF modulators should be clearly marked indicating the available output channels.
+
+## **5.2 Nominal RMS output level**
+
+The Nominal RMS Output level should be  $-3$  dBmV ( $+6/-3$  dB) at 75 ohms.
+
+NOTE – Nominal output signal is based on a reduction of 3 to 6 dB from typical NTSC levels. The value of  $-3$  dBmV at 75 ohms is equivalent to  $-51.8$  dBm in the entire VSB signal (which includes 0.3 dB for the pilot), or  $-119.4$  dBm/Hz in the data portion of the spectrum.
+
+## **5.3 Pilot phase noise**
+
+This clause addresses pilot phase noise for 8 VSB trellis and 16 VSB.
+
+### **5.3.1 Pilot phase noise – 8 VSB trellis**
+
+Pilot Phase Noise should be less than  $-90$  dBc at 20 kHz for 8 VSB trellis.
+
+NOTE – The specification is 12 dB better than the demonstrated threshold of  $-78$  dBc at 20 kHz for 8 VSB (trellis coded) reception.
+
+### **5.3.2 Pilot phase noise – 16 VSB**
+
+Pilot Phase Noise should be less than  $-90$  dBc at 20 kHz for 16 VSB.
+
+NOTE – The specification is 7 dB better than the demonstrated threshold of  $-83$  dBc at 20 kHz for 16 VSB reception.
+
+## **5.4 Error vector magnitude (EVM)**
+
+### **5.4.1 EVM – 8 VSB trellis**
+
+The EVM, in instances without equalization, should be at least 18 dB below the measured output power for 8 VSB trellis. The specification is set to allow simple filtering without phase correction in the remodulator, while leaving sufficient tolerance for additional linear distortion due to home wiring. The EVM, in instances with equalization, should be at least 24 dB below the measured output power. The specification effectively sets a limit on non-linear distortions in the remodulator.
+
+### **5.4.2 EVM – 16 VSB**
+
+The EVM, in instances without equalization, should be at least 18 dB below the measured output power for 16 VSB. The specification is set to allow simple filtering without phase correction in the remodulator, while leaving sufficient tolerance for additional linear distortion due to home wiring. The EVM, in instances with equalization, should be at least 34 dB below the measured output power for 16 VSB. The specification effectively sets a limit on non-linear distortions in the remodulator.
+
+### **5.4.3 EVM definition**
+
+EVM is a measure of performance of the received and demodulated 8 or 16 VSB constellation. EVM will quantify the in-band distortions.
+
+$$EVM = \sqrt{(I_{ref} - I_{meas})^2 + (Q_{ref} - Q_{meas})^2} \quad (5.1)$$
+
+![Figure 3/J.151 – Error vector magnitude. A vector diagram in the I-Q plane. The vertical axis is labeled 'I' and the horizontal axis is labeled 'Q'. A vector labeled 'EVM' originates from the origin and points into the first quadrant. The diagram is labeled 'T0909460-00'.](398674b42e3466add6d47f420c136494_img.jpg)
+
+Figure 3/J.151 – Error vector magnitude. A vector diagram in the I-Q plane. The vertical axis is labeled 'I' and the horizontal axis is labeled 'Q'. A vector labeled 'EVM' originates from the origin and points into the first quadrant. The diagram is labeled 'T0909460-00'.
+
+**Figure 3/J.151 – Error vector magnitude**
+
+In theory the VSB signal has no Q component, Q reference = 0. However, non-linear effects can cause phase distortion which could transfer the vector into the Q domain.
+
+$$EVM(dB) = 10 \log \left[ \frac{\text{Signal Energy}}{\frac{1}{n} \sum_{i=1}^n [EVM_{(n)}/n]} \right] \quad (5.2)$$
+
+## 5.5 Connector
+
+The connector should be an F-type female connector per IEC 60169-24 (1991-11).
+
+## 5.6 Side-band output
+
+A double side-band output is acceptable.
+
+## 5.7 Roll-off specification
+
+All spurious signals that are greater than 12 MHz from the pilot of the desired channel's output signal should be more than 30 dB down from the actual signal level. See Figure 4.
+
+![Figure 4/J.151 – Roll-off. A graph showing the roll-off of a channel filter. The horizontal axis represents frequency offset from the pilot, with markers at -12 MHz, -6 MHz, Band Edge, +6 MHz, and +12 MHz. The vertical axis represents attenuation, with a marker at -30 dB. A dashed line shows the filter's roll-off, and a solid line shows the transmitted channel. The 'Unused Lower Side-band' is indicated between -6 MHz and the Band Edge. The 'Transmitted Channel 6 MHz BW' is indicated between the Band Edge and +6 MHz. The pilot is marked at the Band Edge. The diagram is labeled 'T0909470-00'.](c8cbc7250125f5d48395f1885ef248d9_img.jpg)
+
+Channel Filter Bandwidth =  $\pm 12$  MHz  
+from transmitted pilot
+
+Attenuation @  $\pm 12$  MHz =  $-30$  dB  
+from average transmitted power
+
+$-30$  dB
+
+$-12$  MHz  $-6$  MHz Band Edge  $+6$  MHz  $+12$  MHz
+
+Unused Lower Side-band
+
+Pilot
+
+Transmitted Channel 6 MHz BW
+
+T0909470-00
+
+Figure 4/J.151 – Roll-off. A graph showing the roll-off of a channel filter. The horizontal axis represents frequency offset from the pilot, with markers at -12 MHz, -6 MHz, Band Edge, +6 MHz, and +12 MHz. The vertical axis represents attenuation, with a marker at -30 dB. A dashed line shows the filter's roll-off, and a solid line shows the transmitted channel. The 'Unused Lower Side-band' is indicated between -6 MHz and the Band Edge. The 'Transmitted Channel 6 MHz BW' is indicated between the Band Edge and +6 MHz. The pilot is marked at the Band Edge. The diagram is labeled 'T0909470-00'.
+
+**Figure 4/J.151 – Roll-off**
+
+## 5.8 Data and clock rates
+
+Data and clock rates should be as indicated in Table 1.
+
+**Table 1/J.151 – Data and clock rates**
+
+| VSB Mode      | IRC (Interface Reference Clock) | Input data rate bits per second (bit/s) <sup>1</sup> | Input data rate bytes per second (byte/s) <sup>2</sup> |
+|---------------|---------------------------------|------------------------------------------------------|--------------------------------------------------------|
+| 16 VSB        | 5 381 118                       | 38 785 317                                           | 4 848 164                                              |
+| 8 VSB Trellis | 2 690 559                       | 19 392 658                                           | 2 424 082                                              |
+
+# 6 On-screen display (OSD) support
+
+Figure 5 illustrates a typical OSD system.
+
+![Figure 5/J.151 – Typical OSD system illustration. The diagram shows a Source Device (DVCR, DVD, Satellite Box, Cable Box, etc.) and a DTV Receiver. In the Source Device, a Valid ATSC Transport Stream and an OSD Generator are input to a Mux. The output of the Mux is input to a Remod. The output of the Remod is input to a Demod in the DTV Receiver. The output of the Demod is input to a Demux. The output of the Demux is split into a Valid ATSC Transport Stream and an OSD Interpreter. The diagram is labeled T0909480-00.](ddc7460821484f1ae2835c67955c554c_img.jpg)
+
+Figure 5/J.151 – Typical OSD system illustration. The diagram shows a Source Device (DVCR, DVD, Satellite Box, Cable Box, etc.) and a DTV Receiver. In the Source Device, a Valid ATSC Transport Stream and an OSD Generator are input to a Mux. The output of the Mux is input to a Remod. The output of the Remod is input to a Demod in the DTV Receiver. The output of the Demod is input to a Demux. The output of the Demux is split into a Valid ATSC Transport Stream and an OSD Interpreter. The diagram is labeled T0909480-00.
+
+**Figure 5/J.151 – Typical OSD system illustration**
+
+## 6.1 OSD encapsulation
+
+OSD data should be encapsulated in PES packets, which are then converted to MPEG-2 transport stream packets. See Figure 6.
+
+<sup>1</sup> Includes MPEG2-TS packet sync byte (0 × 47). The effective bit rate, not including MPEG2-TS sync byte is 19 289 506 bit/s and 38 579 012 bit/s.
+
+<sup>2</sup> The input data rate is not an integral number of byte/s. The actual byte/s is derived from the bit rate. The values in this table have been rounded.
+
+![Diagram illustrating OSD data packet encapsulation. At the top, an OSD packet is shown with 'OSD Header' and 'OSD Data'. This is divided into two partitions: 'Partition #1' and 'Partition #2'. Each partition is encapsulated into a PES packet with a 'PES H' header. These PES packets are then segmented into Transport Stream (TS) packets. 'Partition #1' is shown as three TS packets, each with a 'TS H' header. 'Partition #2' is shown as four TS packets: the first has a 'TS H' header, the second has a 'Fill' field, the third has a 'TS H' header, and the fourth has a 'TS H' header. The label 'Transport Stream packets' is at the bottom. A small code 'T0909490-00' is in the bottom right corner of the diagram area.](4801720824e4b5e2361a5564f91cfb70_img.jpg)
+
+Diagram illustrating OSD data packet encapsulation. At the top, an OSD packet is shown with 'OSD Header' and 'OSD Data'. This is divided into two partitions: 'Partition #1' and 'Partition #2'. Each partition is encapsulated into a PES packet with a 'PES H' header. These PES packets are then segmented into Transport Stream (TS) packets. 'Partition #1' is shown as three TS packets, each with a 'TS H' header. 'Partition #2' is shown as four TS packets: the first has a 'TS H' header, the second has a 'Fill' field, the third has a 'TS H' header, and the fourth has a 'TS H' header. The label 'Transport Stream packets' is at the bottom. A small code 'T0909490-00' is in the bottom right corner of the diagram area.
+
+**Figure 6/J.151 – OSD data packet illustration**
+
+### 6.1.1 PES encapsulation
+
+The following restrictions should apply:
+
+- a) **stream\_id** is defined as 0xBF to indicate that this stream should be of type private\_stream\_2.
+- b) OSD data should be carried as the payload of PES packets identified by PID 0x1ABC.
+- c) Each OSD subframe should start a new PES packet.
+- d) The OSD subframe may be transported in more than one PES packet.
+
+In addition, the Transport Stream packets that result from PES segmentation should conform to the following constraints:
+
+- a) **transport\_scrambling\_control** bits should have the value '00'.
+- b) **adaptation\_field\_control** bits should have the value '01'.
+
+For a detailed description of PES encapsulation, see ITU-T H.222.0 | ISO/IEC 13818-1, as constrained by Annex D/J.83.
+
+### 6.1.2 Syntax and semantics for PES packets carrying OSD information
+
+The syntax and semantics for a PES packet carrying OSD information should be as defined in Table 2.
+
+**Table 2/J.151 – PES packet definition for carrying OSD information**
+
+|                               | Bits | Format |
+|-------------------------------|------|--------|
+| <b>OSD_PES_packet() {</b>     |      |        |
+| <b>Start_code_prefix</b>      | 24   | Bslbf  |
+| <b>stream_id</b>              | 8    | 0xBF   |
+| <b>PES_packet_length</b>      | 16   | Uimsbf |
+| <b>Total_partitions</b>       | 8    | Uimsbf |
+| <b>partition_number</b>       | 8    | Uimsbf |
+| <b>version_control</b>        | 5    | Uimsbf |
+| <b>protocol_id</b>            | 3    | Uimsbf |
+| <b>additional_info_length</b> | 8    | Uimsbf |
+| <b>additional_info()</b>      | var  |        |
+| <b>OSD_data()</b>             | var  |        |
+| <b>Reserved</b>               | 32   | rpchof |
+| <b>}</b>                      |      |        |
+
+where:
+
+**start\_code\_prefix**: is a 24-bit field that identifies the beginning of a packet. Its value should be set to 0x000001.
+
+**stream\_id**: is an 8-bit field that should be set to 0xBF (private\_stream\_2) to indicate that the format of the OSD PES packets follows a privately defined protocol.
+
+**PES\_packet\_length**: is a 16-bit field specifying the number of bytes in the PES packet immediately following this field to the end of the PES packet. The value of this field should not exceed 65 529 (equivalently, the maximum size for an OSD PES packet is 65 535 bytes).
+
+**total\_partitions**: is an 8-bit field that specifies the total number of partitions required to carry the OSD datagram using fixed length PES packets. The range for this field should be between 1 and 255 (inclusive).
+
+**partition\_number**: is an 8-bit field that specifies the OSD partition carried in this PES packet. The range for this field should be between 1 and 255 (inclusive).
+
+**version\_control**: is a 5-bit field that identifies the version number of the transmitted OSD. Its value increases by one every time a new OSD subframe is generated and transmitted. If the same subframe is retransmitted, then this value is not incremented. Upon reaching the value 31, it wraps around to 0.
+
+**protocol\_id**: is a 3-bit field that is currently defined as '000'. All other values are reserved for future eventual additions and/or restructuring of the OSD protocol.
+
+**additional\_info\_length**: is an 8-bit field the value of which corresponds to the length in bytes of the **additional\_info** field.
+
+**additional\_info**: is a field designated to contain additional information that may be added eventually in the future. Currently, no additional information exists and therefore the value of the field **additional\_info\_length** is 0x00.
+
+**OSD\_data**: is a subframe header. It may contain data if necessary.
+
+### 6.1.3 Maximum transmission rate for OSD data
+
+The maximum transmission rate for OSD data should not exceed 19.29 Mbit/s<sup>3</sup> averaged over any 100 ms interval. This rate should be further constrained by the requirement that the solid colour fill region subframes should not be transmitted more frequently than fully expanded subframes. Further,
+
+<sup>3</sup> This value does not include the MPEG2-TS packet sync byte (0 × 47). See ITU-T Annex D/J.83, System D.
+
+the OSD source should pause between transmission of a solid colour fill region subframe and the next subframe to permit the subframe to be expanded. Even though the solid colour fill region subframe may be smaller in size than the fully expanded subframe, the processing time required in the OSD consumer is the same. The time in seconds ( $T_s$ ) required to transmit the fully expanded subframe may be calculated as follows:
+
+Step 1: Subframe Width  $\times$  Subframe<sup>4</sup> Height  $\times$  # bits/pixel =  $T_b$
+
+Step 2:  $T_b/19.29$  Mbit/s =  $T_s$
+
+where:
+
+$T_s$  = time in seconds
+
+$T_b$  = total bits to be transmitted
+
+Example calculations follow:
+
+a) A  $640 \times 480$ , 4-bit solid colour fill region subframe
+
+Step 1:  $640 \times 480 \times 4 = 1.23$  Mbit
+
+Step 2:  $1.23$  Mbit/ $19.29$  Mbit/s =  $63.8$  ms
+
+Therefore the OSD source should pause  $63.8$  ms after the transmission of the first solid colour fill region subframe before another subframe is transmitted.
+
+b) A  $300 \times 200$ , 16-bit solid colour fill region subframe
+
+Step 1:  $300 \times 200 \times 16 = 0.96$  Mbit
+
+Step 2:  $0.96$  Mbit/ $19.29$  Mbit/s =  $49.8$  ms
+
+Therefore the OSD source should pause  $49.8$  ms after the transmission of the first solid colour fill region subframe before another subframe is transmitted.
+
+If the OSD producer is making use of the double buffering feature, then it should not assume a frame rate faster than 24 frames per second.
+
+### 6.1.4 OSD retransmission
+
+The consumer device should retransmit the OSD within 1 second, if there has been no change to the OSD.
+
+# 7 OSD data
+
+## 7.1 Format of OSD data
+
+In this clause the source of the OSD signal is called the OSD Producer and the DTV Display is called the OSD Consumer.
+
+### 7.1.1 Subframe types
+
+The defined subframe types are:
+
+**Set\_OSD\_pixel\_format:** Establishes the format of the basic 16-bit pixels that make up the data definition to follow, and the size and colour depth of the OSD grid. For OSD grid formats with either 4- or 8-bit colour depths, the subframe should contain either a 4- or 8-bit Colour Look-up Table (CLUT).
+
+---
+
+<sup>4</sup> All references in this Recommendation to resolutions, such as  $640 \times 480$ , are termed as width  $\times$  height.
+
+**4\_bit\_OSD\_data:** Defines 4-bit pixels in a rectangular region. Each 4-bit pixel represents a colour/alpha blend value derived by indirection through the 4-bit CLUT.
+
+**8\_bit\_OSD\_data:** Defines 8-bit pixels in a rectangular region. Each 8-bit pixel represents a colour/alpha blend value derived by indirection through the 8-bit CLUT.
+
+**Uncompressed\_16\_bit\_data:** Defines raw uncompressed 16-bit OSD data in a rectangular region.
+
+**Fill\_region\_with\_constant:** Defines a rectangular region to fill with a 16-bit constant with a format defined by **pixel\_format**.
+
+**Clear\_OSD:** Should load the complete OSD with a transparent value.
+
+### 7.1.2 Subframe typeCode
+
+The type of each subframe is identified by a **typeCode** field, as defined in Table 3. All subframes in this protocol, as well as ones defined in future extensions, are formatted with the 8-bit **typeCode** and 24-bit **dataLength** in the first quadlet. OSD Consumer equipment that encounters a subframe with an unknown **typeCode** should use the **dataLength** to skip that subframe.
+
+**Table 3/J.151 – typeCode coding**
+
+| <b>typeCode</b> | <b>Meaning</b>                   |
+|-----------------|----------------------------------|
+| 0               | Reserved                         |
+| 1               | <b>Set_OSD_pixel_format</b>      |
+| 2               | <b>4_bit_OSD_data</b>            |
+| 3               | <b>8_bit_OSD_data</b>            |
+| 4               | <b>Uncompressed_16_bit_data</b>  |
+| 5               | <b>Fill_region_with_constant</b> |
+| 6               | <b>Clear_OSD</b>                 |
+| 7-255           | Reserved for future use          |
+
+### 7.1.3 Subframe processing
+
+The DTV should process subframes in the order received. A DTV may not have buffer space sufficient to hold a complete frame of OSD data; if that is the case, processing of subframes as they arrive will be necessary. In any case, the DTV should process each subframe as it arrives.
+
+### 7.1.4 Subframe syntax and definition
+
+#### 7.1.4.1 Set OSD pixel format subframe
+
+The OSD Producer device should use the **Set\_OSD\_pixel\_format** subframe to set the pixel format, colour depth, and CLUT (if applicable) for subsequent delivery of OSD data.
+
+The **Set\_OSD\_pixel\_format** subframe should be formatted as shown in Figure 7 when **OSD\_layout** specifies a 16-bit colour depth.
+
+![Figure 7/J.151 – Set OSD pixel format subframe, 16-bit colour depth. A diagram showing a 16-bit word structure. The first byte is 'typeCode'. The second byte is 'OSD_layout'. The third byte is 'overlay_format'. The fourth byte is 'pixel_format'. The fifth byte is split into nibbles: '0', 'cs', 'buf', 'sw'. The sixth byte is 'mix'. The seventh byte is 'fill_value'. The eighth byte is 'reserved'. MSB (first) is at the top left, LSB is at the bottom right. Reference code T0909500-00 is at the bottom right.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg)
+
+Figure 7/J.151 – Set OSD pixel format subframe, 16-bit colour depth. A diagram showing a 16-bit word structure. The first byte is 'typeCode'. The second byte is 'OSD\_layout'. The third byte is 'overlay\_format'. The fourth byte is 'pixel\_format'. The fifth byte is split into nibbles: '0', 'cs', 'buf', 'sw'. The sixth byte is 'mix'. The seventh byte is 'fill\_value'. The eighth byte is 'reserved'. MSB (first) is at the top left, LSB is at the bottom right. Reference code T0909500-00 is at the bottom right.
+
+Figure 7/J.151 – Set OSD pixel format subframe, 16-bit colour depth
+
+The **Set\_OSd\_pixel\_format** subframe should be formatted as shown in Figure 8 when **OSD\_layout** specifies a 4-bit colour depth.
+
+![Figure 8/J.151 – Set OSD pixel format subframe, 4-bit colour depth. A diagram showing a 16-bit word structure. The first byte is 'typeCode'. The second byte is 'OSD_layout'. The third byte is 'overlay_format'. The fourth byte is 'pixel_format'. The fifth byte is split into nibbles: '0', 'cs', 'buf', 'sw'. The sixth byte is 'mix'. The seventh byte is 'fill_value'. The eighth byte is 'reserved'. The ninth byte is 'CLUT[0]'. The tenth byte is 'CLUT[1]'. The eleventh byte is '...'. The twelfth byte is 'CLUT[14]'. The thirteenth byte is 'CLUT[15]'. MSB (first) is at the top left, LSB is at the bottom right. Reference code T0909510-00 is at the bottom right.](4356776ca004ecba5d599667a155d7d4_img.jpg)
+
+Figure 8/J.151 – Set OSD pixel format subframe, 4-bit colour depth. A diagram showing a 16-bit word structure. The first byte is 'typeCode'. The second byte is 'OSD\_layout'. The third byte is 'overlay\_format'. The fourth byte is 'pixel\_format'. The fifth byte is split into nibbles: '0', 'cs', 'buf', 'sw'. The sixth byte is 'mix'. The seventh byte is 'fill\_value'. The eighth byte is 'reserved'. The ninth byte is 'CLUT[0]'. The tenth byte is 'CLUT[1]'. The eleventh byte is '...'. The twelfth byte is 'CLUT[14]'. The thirteenth byte is 'CLUT[15]'. MSB (first) is at the top left, LSB is at the bottom right. Reference code T0909510-00 is at the bottom right.
+
+Figure 8/J.151 – Set OSD pixel format subframe, 4-bit colour depth
+
+The **Set\_OSd\_pixel\_format** subframe should be formatted as shown in Figure 9 when **OSD\_layout** specifies an 8-bit colour depth.
+
+![Figure 9/J.151 – Set OSD pixel format subframe, 8-bit colour depth. A diagram showing a 16-bit word structure. The first byte is 'typeCode'. The second byte is 'OSD_layout'. The third byte is 'overlay_format'. The fourth byte is 'pixel_format'. The fifth byte is split into nibbles: '0', 'cs', 'buf', 'sw'. The sixth byte is 'mix'. The seventh byte is 'fill_value'. The eighth byte is 'reserved'. The ninth byte is 'CLUT[0]'. The tenth byte is 'CLUT[1]'. The eleventh byte is '...'. The twelfth byte is 'CLUT[254]'. The thirteenth byte is 'CLUT[255]'. MSB (first) is at the top left, LSB is at the bottom right. Reference code T0909520-00 is at the bottom right.](8592a32c2fdf17c1e562f0ba6b7e8e1a_img.jpg)
+
+Figure 9/J.151 – Set OSD pixel format subframe, 8-bit colour depth. A diagram showing a 16-bit word structure. The first byte is 'typeCode'. The second byte is 'OSD\_layout'. The third byte is 'overlay\_format'. The fourth byte is 'pixel\_format'. The fifth byte is split into nibbles: '0', 'cs', 'buf', 'sw'. The sixth byte is 'mix'. The seventh byte is 'fill\_value'. The eighth byte is 'reserved'. The ninth byte is 'CLUT[0]'. The tenth byte is 'CLUT[1]'. The eleventh byte is '...'. The twelfth byte is 'CLUT[254]'. The thirteenth byte is 'CLUT[255]'. MSB (first) is at the top left, LSB is at the bottom right. Reference code T0909520-00 is at the bottom right.
+
+Figure 9/J.151 – Set OSD pixel format subframe, 8-bit colour depth
+
+The source should send the **Set\_OSD\_pixel\_format** subframe prior to the initial delivery of OSD data to establish the format for the data to follow. The subframe should also be sent prior to delivery of OSD data in a different pixel format. Note that it is not possible to define one OSD image as a mixture of different pixel formats (**pixel\_format** 0 and 1, for example).
+
+The **Set\_OSD\_pixel\_format** subframe also selects one of possibly several OSD buffer formats offered by the OSD Consumer.
+
+**typeCode** for the **Set\_OSD\_pixel\_format** subframe is 01<sub>16</sub>.
+
+**dataLength** should reflect the number of bytes in the subframe following the **dataLength** field itself, either 8, 40, or 520, depending upon the colour depth defined in **OSD\_layout**.
+
+**OSD\_layout** specifies the OSD frame buffer dimensions and colour depth and should be as specified in Table 4.
+
+**Table 4/J.151 – OSD layout coding**
+
+| <b>OSD_layout</b> | <b>Meaning</b>             |
+|-------------------|----------------------------|
+| 0                 | $640 \times 480 \times 4$  |
+| 1                 | $640 \times 480 \times 8$  |
+| 2                 | $640 \times 480 \times 16$ |
+| 3-255             | Reserved for future use    |
+
+**overlay\_format** specifies the way the OSD Consumer should overlay the selected grid format over decoded video. Table 5 defines coding for **overlay\_format**. Support for formats 1 and 2 is optional. All devices should support format 0.
+
+**Table 5/J.151 – Overlay format coding**
+
+| <b>overlay_format</b> | <b>Meaning</b>               |
+|-----------------------|------------------------------|
+| 0                     | no stretch requested         |
+| 1                     | Stretch horizontally to 14:9 |
+| 2                     | Stretch horizontally to 16:9 |
+| 3-255                 | Reserved for future use      |
+
+**pixel\_format** should be as specified in Table 6. The format for the 16 bit pixel for each pixel format is as shown in Figure 10.
+
+**Table 6/J.151 – Pixel format coding**
+
+| <b>pixel_format</b> | <b>Meaning</b>          |
+|---------------------|-------------------------|
+| 0                   | $Y:C_b:C_r = 6:5:5$     |
+| 1                   | $a:Y:C_b:C_r = 2:6:4:4$ |
+| 2                   | $a:Y:C_b:C_r = 4:6:3:3$ |
+| 3-255               | Reserved for future use |
+
+A zero value for Y indicates lowest luminance (most black). A maximum value for Y (all ones) indicates highest luminance level. Y is related to primary colour signals (R, G, B) in accordance with the colourimetry clauses of ITU-R BT.709-2, the standard for DTV, or ITU-R BT.601-4, the
+
+standard for NTSC. An OSD consumer may only support one of the standards; as the complexity of requiring support for both was deemed excessive for the improvement in quality that would result.  $C_r$  and  $C_b$  are chrominance vectors related to primary colour signals (R, G, B) in accordance with ITU-R BT.709-2 or ITU-R BT.601-4.
+
+For **pixel\_format** 0 only, any pixel with a Y value of zero should be transparent. Pixels with non-zero values of Y should be opaque.
+
+![Diagram showing pixel format bit fields for pixel_format 0, 1, and 2. Each format is shown as a horizontal bar with MSB on the left and LSB on the right. pixel_format 0 contains Y, Cb, and Cr. pixel_format 1 contains alpha, Y, Cb, and Cr. pixel_format 2 contains alpha, Y, Cb, and Cr. A small code T0909530-00 is at the bottom right.](5445597cceefaca1ac89e710fe339325_img.jpg)
+
+The diagram illustrates the bit field structure for three pixel formats. Each format is represented by a horizontal bar with 'MSB' (Most Significant Bit) at the left and 'LSB' (Least Significant Bit) at the right. The fields are labeled as follows:
+
+- pixel\_format 0:** Contains three fields: Y,  $C_b$ , and  $C_r$ .
+- pixel\_format 1:** Contains four fields:  $\alpha$ , Y,  $C_b$ , and  $C_r$ .
+- pixel\_format 2:** Contains four fields:  $\alpha$ , Y,  $C_b$ , and  $C_r$ .
+
+A small code 'T0909530-00' is located at the bottom right of the diagram.
+
+Diagram showing pixel format bit fields for pixel\_format 0, 1, and 2. Each format is shown as a horizontal bar with MSB on the left and LSB on the right. pixel\_format 0 contains Y, Cb, and Cr. pixel\_format 1 contains alpha, Y, Cb, and Cr. pixel\_format 2 contains alpha, Y, Cb, and Cr. A small code T0909530-00 is at the bottom right.
+
+Figure 10/J.151 – Pixel format bit fields
+
+**a** is an alpha level associated with pixels in **pixel\_format** 1 or 2. **a** values for **pixel\_format** 1 are defined in Table 7. For **pixel\_format** 2, values in between 0 and all-ones indicate the mix weight between the OSD pixel and decoded video for each pixel. A zero value for **a** indicates transparent. The all-ones value indicates opaque. The interpolation between zero and all ones should be approximately linear.
+
+The **mix** parameter in the **Set\_OSD\_pixel\_format** subframe is used with **pixel\_format** 1 to specify the alpha-blend value to use for pixels that are neither transparent nor opaque. Table 7 should define the interpretation of the 2-bit alpha field in pixels formatted as **pixel\_format** 1. The **mix** parameter should be ignored in an OSD Consumer for pixel formats 0 and 2.
+
+Table 7/J.151 – A field interpretation for pixel\_format 1
+
+| pixel a | Meaning                                                                               |
+|---------|---------------------------------------------------------------------------------------|
+| 0       | Opaque                                                                                |
+| 1       | Mix with video using <b>mix</b> parameter in the <b>Set_OSD_pixel_format</b> subframe |
+| 2       | Transparent                                                                           |
+| 3       | Reserved for future use                                                               |
+
+**cs** defines the chrominance standard used in the OSD Producer, and acts to notify the OSD Consumer that it should interpret Y-Cb-Cr data in accordance with the referenced standard, if possible. **cs** is defined in Table 8.
+
+**Table 8/J.151 – Colourimetry standards**
+
+| <b>cs</b> | <b>Colour Standard</b> |
+|-----------|------------------------|
+| 0         | ITU-R BT.709-2         |
+| 1         | ITU-R BT.601-4         |
+
+**buf** indicates whether data is placed into the buffer currently being used for output (**buf** = 0) or into a buffer that is not currently being used for output (**buf** = 1). The **buf** and **sw** bits together specify how the data update will take place as shown in Table 9.
+
+When double buffering is not supported in the OSD consumer, **buf** = 1 has no meaning. In this case the OSD consumer may ignore subframes with **buf** = 1.
+
+**Table 9/J.151 – buf/sw coding**
+
+| <b>buf</b> | <b>sw</b> | <b>Rule</b>                                                                                                                              |
+|------------|-----------|------------------------------------------------------------------------------------------------------------------------------------------|
+| 0          | 0         | Should put data into the active buffer immediately                                                                                       |
+| 0          | 1         | Should start to put data into the active buffer synchronized with the start of the next vertical retrace                                 |
+| 1          | 0         | Should put data into an off-screen buffer                                                                                                |
+| 1          | 1         | Should put data into an off-screen buffer and then swap with the active buffer, synchronized with the start of the next vertical retrace |
+
+**sw** indicates when the data update will take place. The **buf** and **sw** bits together specify how the data update will take place as shown in Table 9.
+
+**fill\_value** is formatted according to **OSD\_Layout** as shown in Table 10.
+
+**Table 10/J.151 – fill\_value coding**
+
+| <b>OSD_layout</b> | <b>fill_value format</b>                 |
+|-------------------|------------------------------------------|
+| 0                 | 4 bits (right justified)                 |
+| 1                 | 8 bits (right justified)                 |
+| 2                 | as defined by <b>pixel_format</b> Coding |
+| 3-255             | Reserved                                 |
+
+For Set\_OSD\_pixel\_format purposes, Set OSD pixel format subframe, Item 1 below states "Processing the first **Set\_OSD\_pixel\_format** subframe after establishing the OSD connection should have the effect of setting the OSD frame buffers to the fill pixel value provided in the command." For purposes of compliance with this Recommendation, the condition "...after establishing the OSD connection...", should mean "...after an OSD producer has been selected...".
+
+Processing within the OSD Consumer of the **Set\_OSD\_pixel\_format** subframe should conditionally cause the OSD frame buffers to be initialized to the **fill\_value** value provided:
+
+- 1) Processing the first **Set\_OSD\_pixel\_format** subframe after establishing the OSD connection should have the effect of setting the OSD frame buffers to the fill pixel value provided in the command.
+- 2) Processing a subsequent **Set\_OSD\_pixel\_format** subframe that changes the **pixel\_format** or **OSD\_layout**, the DTV should initialize the OSD buffers to the fill pixel value provided.
+
+Processing a subsequent **Set\_OSD\_pixel\_format** subframe that changes only the **mix** field or CLUT data, previously defined pixel data values do not change.
+
+**CLUT[N]** is a colour look-up table entry. CLUT entries are 16-bits, formatted according to the pixel format defined in **pixel\_format**.
+
+#### 7.1.4.2 4-bit OSD data subframe
+
+Figure 11 defines the format of the **4\_bit\_OSD\_data** subframe, used to deliver 4-bit pixels from A/V Source to display.
+
+![Diagram of the 4-bit OSD data subframe format. The diagram shows a sequence of fields: typeCode (0, buf, sw), dataLength, X_loc (0016), Y_loc, width, height, pixel[0] through pixel[N], zeroPad1, and zeroPad2. The diagram is labeled MSB (first) at the top left and LSB at the top right. A bracket on the right side indicates the end of the subframe. The identifier T0909540-00 is at the bottom right.](e180f2b5fcbe8001554a7c0677cd3f82_img.jpg)
+
+The diagram illustrates the structure of a 4-bit OSD data subframe. It begins with the **typeCode** field, which includes sub-fields **0**, **buf**, and **sw**. This is followed by the **dataLength** field. The **X\_loc** field is shown as **00<sub>16</sub>**. The **Y\_loc** field follows. The **width** and **height** fields are then present. The pixel data is represented by **pixel[0]**, **pixel[1]**, **pixel[2]**, **pixel[3]**, an ellipsis, **pixel[N]**, and another ellipsis. The subframe ends with **zeroPad1** and **zeroPad2** padding fields. The diagram is labeled **MSB (first)** at the top left and **LSB** at the top right. A bracket on the right side indicates the end of the subframe. The identifier **T0909540-00** is at the bottom right.
+
+Diagram of the 4-bit OSD data subframe format. The diagram shows a sequence of fields: typeCode (0, buf, sw), dataLength, X\_loc (0016), Y\_loc, width, height, pixel[0] through pixel[N], zeroPad1, and zeroPad2. The diagram is labeled MSB (first) at the top left and LSB at the top right. A bracket on the right side indicates the end of the subframe. The identifier T0909540-00 is at the bottom right.
+
+Figure 11/J.151 – 4-bit OSD data subframe format
+
+**typeCode** should be set to value 02<sub>16</sub>, indicating the **4\_bit\_OSD\_data** subframe format.
+
+The 24-bit **dataLength** field should be set to indicate the number of data bytes in the remainder of the subframe. The subframe should be padded so that the next subframe address is quadlet aligned. Based on the height and width parameters (if both are odd numbers), the least significant 4 bits in the last data byte may be unused.
+
+**X\_loc** is the 12-bit X-coordinate (column number) within the image buffer in the buffer indicated by **buf**. The coordinate system is defined with 0,0 in the upper left corner.
+
+**Y\_loc** is the 12-bit Y-coordinate (row number) within the image buffer in the buffer indicated by **buf**.
+
+![Figure 12/J.151 – Pixel data display order. A diagram showing a 4x6 grid of pixels labeled P0 through P23. The grid is defined by X_loc (top-left corner), width (6 pixels), and height (4 pixels). The pixels are displayed in scan order: left-to-right, top-to-bottom. Row 1: P0, P1, P2, P3, P4, P5. Row 2: P6, P7, P8, P9, P10, P11. Row 3: P12, P13, P14, P15, P16, P17. Row 4: P18, P19, P20, P21, P22, P23. Arrows indicate the flow from P0 to P23. A label 'T0909550-00' is at the bottom right.](c914f51f4427bc672dd0526cfc90ebe9_img.jpg)
+
+Figure 12/J.151 – Pixel data display order. A diagram showing a 4x6 grid of pixels labeled P0 through P23. The grid is defined by X\_loc (top-left corner), width (6 pixels), and height (4 pixels). The pixels are displayed in scan order: left-to-right, top-to-bottom. Row 1: P0, P1, P2, P3, P4, P5. Row 2: P6, P7, P8, P9, P10, P11. Row 3: P12, P13, P14, P15, P16, P17. Row 4: P18, P19, P20, P21, P22, P23. Arrows indicate the flow from P0 to P23. A label 'T0909550-00' is at the bottom right.
+
+Figure 12/J.151 – Pixel data display order
+
+**buf** and **sw** are the same as defined in 7.1.4.1, **Set\_OSD\_pixel\_format** subframe.
+
+**width** is a 16-bit unsigned integer number representing the width, in pixels, of the OSD region being defined. Value zero is undefined.
+
+**height** is a 16-bit unsigned integer number representing the height, in pixels, of the OSD region being defined. Value zero is undefined.
+
+**pixel[0]** through **pixel[N]** are 4-bit pixel values. The pixels should be listed in a scan order that is left to right and top to bottom. An illustration of the order is shown in Figure 12. In this particular example **width** has a value of 6 and **height** has a value of 4. The display values for each should be expanded through the 4-bit to 16-bit CLUT defined in the most recently received **Set\_OSD\_pixel\_format** subframe.
+
+#### 7.1.4.3 8-bit OSD data subframe
+
+Figure 13 defines the format of the **8\_bit\_OSD\_data** subframe, used to deliver 8-bit pixels from an OSD Producer to an OSD Consumer.
+
+![Figure 13/J.151 – 8-bit OSD data subframe format. A diagram showing the structure of an 8-bit OSD data subframe. The subframe is divided into fields: typeCode (bits 0, buf, sw), X_loc, dataLength (0016), Y_loc, width, height, pixel[0], pixel[1], pixel[2], pixel[3], ..., pixel[N], and zeroPad1. The diagram shows the MSB (first) on the left and LSB on the right. A label 'T0909560-00' is at the bottom right.](6f31cdb576d2f15c35c3f266e5f59211_img.jpg)
+
+Figure 13/J.151 – 8-bit OSD data subframe format. A diagram showing the structure of an 8-bit OSD data subframe. The subframe is divided into fields: typeCode (bits 0, buf, sw), X\_loc, dataLength (0016), Y\_loc, width, height, pixel[0], pixel[1], pixel[2], pixel[3], ..., pixel[N], and zeroPad1. The diagram shows the MSB (first) on the left and LSB on the right. A label 'T0909560-00' is at the bottom right.
+
+Figure 13/J.151 – 8-bit OSD data subframe format
+
+**typeCode** should be set to value 03<sub>16</sub>, indicating the **8\_bit\_OSD\_data** subframe format.
+
+The definitions for **dataLength**, **X\_loc**, **Y\_loc**, **width** and **height** are the same as for the **4\_bit\_OSD\_data** subframe.
+
+The definitions for **buf** and **sw** are the same as defined in 7.1.4.1, **Set\_OSD\_pixel\_format** subframe.
+
+**pixel[0]** through **pixel[N]** are 8-bit pixel values. The display values for each should be derived by indirection through the 8-bit CLUT defined in the last received **Set\_OSD\_pixel\_format** subframe. The pixels should be listed in a scan order as shown in Figure 12.
+
+#### 7.1.4.4 Uncompressed 16-bit data subframe
+
+Figure 14 defines the format of the **Uncompressed\_16\_bit\_data** subframe, used to deliver uncompressed 16-bit pixels from A/V Source to display.
+
+![Figure 14/J.151 – Uncompressed 16-bit data subframe format diagram. The diagram shows a subframe structure with fields: typeCode, dataLength, X_loc, Y_loc, width, height, pixel[0], pixel[1], pixel[N], zeroPad1, and zeroPad2. It is divided into MSB (first) and LSB sections.](171115f072e42b379238ed0dd438e9d7_img.jpg)
+
+The diagram illustrates the layout of an Uncompressed 16-bit data subframe. It is divided into two main sections: MSB (first) on the left and LSB on the right. The fields are arranged as follows:
+
+- typeCode**: Located in the MSB section, containing sub-fields 0, buf, and sw.
+- dataLength**: Located in the MSB section, containing sub-fields 00<sub>16</sub> and Y\_loc.
+- X\_loc**: Located in the MSB section.
+- width**: Located in the MSB section.
+- height**: Located in the LSB section.
+- pixel[0]**: Located in the MSB section.
+- pixel[1]**: Located in the LSB section.
+- ...**: Ellipsis indicating intermediate pixel values.
+- pixel[N]**: Located in the MSB section.
+- zeroPad1**: Located in the LSB section.
+- zeroPad2**: Located in the LSB section.
+
+A dashed line separates the pixel data from the zero-padding. An arrow points from the end of pixel[N] to the start of zeroPad1.
+
+Figure 14/J.151 – Uncompressed 16-bit data subframe format diagram. The diagram shows a subframe structure with fields: typeCode, dataLength, X\_loc, Y\_loc, width, height, pixel[0], pixel[1], pixel[N], zeroPad1, and zeroPad2. It is divided into MSB (first) and LSB sections.
+
+Figure 14/J.151 – Uncompressed 16-bit data subframe format
+
+**typeCode** should be set to value 04<sub>16</sub>, indicating the **Uncompressed\_16\_bit\_data** subframe format.
+
+The definitions for **dataLength**, **X\_loc**, **Y\_loc**, **width** and **height** are the same as for the **4\_bit\_OSD\_data** subframe.
+
+The definitions for **buf** and **sw** are the same as defined in 7.1.4.1, **Set\_OSD\_pixel\_format** subframe.
+
+**pixel[0]** through **pixel[N]** are 16-bit pixel values. The format of each pixel (in terms of luminance, chrominance, and optional alpha level) are as defined by the **Set\_OSD\_pixel\_format** subframe. The pixels should be listed in a scan order as shown in Figure 12.
+
+#### 7.1.4.5 Fill region with constant subframe
+
+Figure 15 defines the format of the **Fill\_region\_with\_constant** subframe, used to direct the display to fill a rectangular area in the display image buffer with a constant value.
+
+![](7133ccf78043568ca62ecbcd43628a4a_img.jpg)
+
+|             |     |    |  |  |  |            |  |  |  |  |  |                  |  |  |       |  |  |  |  |  |  |  |  |
+|-------------|-----|----|--|--|--|------------|--|--|--|--|--|------------------|--|--|-------|--|--|--|--|--|--|--|--|
+| MSB (first) |     |    |  |  |  |            |  |  |  |  |  | LSB              |  |  |       |  |  |  |  |  |  |  |  |
+| typeCode    |     |    |  |  |  | dataLength |  |  |  |  |  |                  |  |  |       |  |  |  |  |  |  |  |  |
+| 0           | buf | sw |  |  |  | X_loc      |  |  |  |  |  | 00 <sub>16</sub> |  |  | Y_loc |  |  |  |  |  |  |  |  |
+| width       |     |    |  |  |  |            |  |  |  |  |  | height           |  |  |       |  |  |  |  |  |  |  |  |
+| fill_value  |     |    |  |  |  |            |  |  |  |  |  | reserved         |  |  |       |  |  |  |  |  |  |  |  |
+
+T0909580-00
+
+Figure 15/J.151 – Fill region with constant subframe format
+
+**typeCode** should be set to value 05<sub>16</sub>, indicating the **Fill\_region\_with\_constant** subframe format.
+
+The 24-bit **dataLength** field should be set to 12 for this subframe type.
+
+The definitions for **dataLength**, **X\_loc**, **Y\_loc**, **width** and **height** are the same as for the **4\_bit\_OSD\_data** subframe.
+
+The definitions for **buf** and **sw** are the same as defined in 7.1.4.1, **Set\_OSD\_pixel\_format** subframe.
+
+**Fill\_Value** indicates the constant value to be filled. The format of **fill\_value** should be as defined by Table 10.
+
+Some implementations of DTVs may provide a feature that allows the colour of the area surrounding the defined OSD grid to be defined. The OSD Producer may specify the fill colour for the surrounding area by setting the **width** and **height** fields to FF<sub>16</sub>.
+
+#### 7.1.4.6 Clear OSD subframe
+
+Figure 16 defines the format of the **Clear\_OSD** subframe, used to direct the display to fill the display image buffer with a zero (Transparent) value.
+
+![](303fadfb9def251d1575d6221199b158_img.jpg)
+
+|             |  |  |  |  |  |            |  |  |  |  |  |     |  |  |  |  |  |  |  |  |  |  |  |
+|-------------|--|--|--|--|--|------------|--|--|--|--|--|-----|--|--|--|--|--|--|--|--|--|--|--|
+| MSB (first) |  |  |  |  |  |            |  |  |  |  |  | LSB |  |  |  |  |  |  |  |  |  |  |  |
+| typeCode    |  |  |  |  |  | dataLength |  |  |  |  |  |     |  |  |  |  |  |  |  |  |  |  |  |
+
+T0909590-00
+
+Figure 16/J.151 – Clear\_OSD subframe format
+
+**typeCode** should be set to value 06<sub>16</sub>, indicating the **Clear\_OSD** subframe format.
+
+The 24-bit **dataLength** field should be set to 0 for this subframe type.
+
+## 7.2 Alignment of OSD with video
+
+A Square pixel aspect ratio is desirable. The OSD consumer should align the 640 × 480 display grid with video according to the constraints:
+
+- a) The 640 × 480 grid should be centered horizontally within the visible display area.
+- b) The 640 × 480 grid should be centered vertically within the visible display area, or cover it completely.
+
+# 8 Capability profiles
+
+This clause defines the capability profiles for the RF DTV interface. At present, two profiles are defined. Future extensions to this protocol may define additional profiles.
+
+All OSD consumers using OSDs should have the capabilities defined in Profile 1 of Table 11 and the OSD capabilities defined in Profile 1 of Table 12. Profile 1 is intended to define the capabilities for near-term designs. Profile 2 is intended to identify prospective capabilities for future designs.
+
+**Table 11/J.151 – Capability profiles**
+
+| Capability                                                | Profile 1 | Profile 2 |
+|-----------------------------------------------------------|-----------|-----------|
+| RF Demodulator 8 VSB (trellis coded)                      | ✓         | ✓         |
+| RF Demodulator 16 VSB                                     | ✓         | ✓         |
+| Decodes All Video Formats                                 | ✓         | ✓         |
+| Delivery Format Supports Region-Based Updating            | ✓         | ✓         |
+| Pixel transparency support (Transparent or Opaque Pixels) | ✓         | ✓         |
+| Double Buffering                                          |           | ✓         |
+
+**Table 12/J.151 – OSD capability profiles**
+
+| Capability                                                                                                                                                                                                                                                                                              | Profile 1 | Profile 2   |
+|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------|-------------|
+| 640 × 480 × 4 OSD grid, 4-bit to 16-bit CLUT format:<br>$\alpha$ , YC <sub>B</sub> C <sub>R</sub> , 2:6:4:4, transparent, opaque or per-screen alpha value<br>$\alpha$ , YC <sub>B</sub> C <sub>R</sub> , 4:6:3:3, transparent, opaque or alpha value per pixel                                         | ✓         | ✓<br>✓      |
+| 640 × 480 × 8 OSD grid, 8-bit to 16-bit CLUT format:<br>$\alpha$ , YC <sub>B</sub> C <sub>R</sub> , 2:6:4:4, transparent, opaque or per-screen alpha value<br>$\alpha$ , YC <sub>B</sub> C <sub>R</sub> , 4:6:3:3, transparent, opaque or alpha value per pixel<br>YC <sub>B</sub> C <sub>R</sub> 6:5:5 |           | ✓<br>✓<br>✓ |
+| 640 × 480 × 16 OSD grid, pixel format:<br>$\alpha$ , YC <sub>B</sub> C <sub>R</sub> , 2:6:4:4, transparent, opaque or per-screen alpha value<br>$\alpha$ , YC <sub>B</sub> C <sub>R</sub> , 4:6:3:3, transparent, opaque or alpha value per pixel<br>YC <sub>B</sub> C <sub>R</sub> 6:5:5               |           | ✓<br>✓<br>✓ |
+
+# 9 DTV RF remodulator input specifications
+
+## 9.1 Input overview
+
+An overview of input to the DTV remodulator is provided in Figure 17. If the device is partitioned as indicated in Figure 17, then it is expected (in general) that:
+
+- The remodulator should support transport streams for both the 16 VSB high data rate transmission mode and the 8 VSB (trellis coded) transmission mode.
+- The remodulator should support 3.3V Process TTL Logic Levels.
+- The f(sym) is equal to 10 762 238 Hz.  $(4.5E6 \times 684/286) \pm 10$  ppm.
+
+![Figure 17/J.151 – Remodulator system diagram. The diagram shows a 'Baseband Data Source (or) Input Buffer' on the left and a 'Remodulator' on the right. 'Valid Transport Streams' enter the source from the left. The source outputs 'In_Data[7..0]' and 'Data_Valid' to the remodulator. The remodulator outputs 'Data Request' and 'Interface Reference Clock (IRC)' back to the source. A 'Master Clock' is shown connected to the remodulator. The identifier 'T0909600-00' is present near the remodulator.](aaf3e6e44cdeabd6d1df869c5f392ea1_img.jpg)
+
+```
+
+graph LR
+    VTS[Valid Transport Streams] --> BDS[Baseband Data Source  
+(or)  
+Input Buffer]
+    BDS -- In_Data[7..0] --> REM[Remodulator]
+    BDS -- Data_Valid --> REM
+    REM -- Data Request --> BDS
+    REM -- IRC[Interface Reference Clock (IRC)] --> BDS
+    MC[Master Clock] --> REM
+    T0909600-00 --- REM
+  
+```
+
+Figure 17/J.151 – Remodulator system diagram. The diagram shows a 'Baseband Data Source (or) Input Buffer' on the left and a 'Remodulator' on the right. 'Valid Transport Streams' enter the source from the left. The source outputs 'In\_Data[7..0]' and 'Data\_Valid' to the remodulator. The remodulator outputs 'Data Request' and 'Interface Reference Clock (IRC)' back to the source. A 'Master Clock' is shown connected to the remodulator. The identifier 'T0909600-00' is present near the remodulator.
+
+**Figure 17/J.151 – Remodulator system**
+
+## 9.2 Input from remodulator to source
+
+In general
+
+- The **IRC... (Interface Reference Clock)** is generated from the Master Clock to provide the frequency reference.
+- The **Data\_Request...** is generated to provide timing for the data pull from the source device. (Active High for 188 cycles).
+- The first byte of packet is the  $0 \times 47$  MPEG Sync.
+- There are 313 packet cycles, 312 with Data\_Request active and 1 with Data\_Request inactive.
+
+## 9.3 Input from source to remodulator
+
+In general
+
+- The **In\_Data...** is an 8 bit Parallel (Byte Wide) data bus.
+- The **Data\_Valid...** is active high (for 188 cycles) starting at packet sync ( $0 \times 47$ ). See Figure 18.
+- There are 313 packet cycles, 312 with Data\_Valid active and 1 with Data\_Valid inactive.
+
+Figure 18 provides a detailed illustration of the preceding three points.
+
+![Timing diagram for Data_Valid signal. The diagram shows four waveforms: Byte_Clk (top), In_Data[7..0] (second from top), Data_Valid (third from top), and IRC (bottom). Byte_Clk is a periodic square wave. In_Data[7..0] shows data segments: 47H, D[0], D[1], D[184], D[185], D[186]. Data_Valid is high for 188 cycles, starting 3 1/2 cycles after the first data segment begins. Data_Request is also high for 188 cycles, starting at the same time as Data_Valid. IRC is a periodic square wave.](8c348bf9c2c81b018017ae1d19506a9a_img.jpg)
+
+Timing diagram for Data\_Valid signal. The diagram shows four waveforms: Byte\_Clk (top), In\_Data[7..0] (second from top), Data\_Valid (third from top), and IRC (bottom). Byte\_Clk is a periodic square wave. In\_Data[7..0] shows data segments: 47H, D[0], D[1], D[184], D[185], D[186]. Data\_Valid is high for 188 cycles, starting 3 1/2 cycles after the first data segment begins. Data\_Request is also high for 188 cycles, starting at the same time as Data\_Valid. IRC is a periodic square wave.
+
+**Figure 18/J.151 – Data\_Valid timing**
+
+# 10 Monitor mode
+
+## 10.1 Monitor mode overview
+
+In this system, the DTV receiver tunes according to the PSIP tables present in the transport stream. The PSIP tables contain the virtual channel identification information (the major and minor channel number) and actual frequency on which the digital signal is transmitted, as well as other data such as time and programming information. In some situations, a "monitor" mode may be needed in DTV receivers.
+
+In a remodulator system, a source unit produces a transport stream that is intended to be sent to the DTV receiver via an RF cable to the terrestrial RF input. The manufacturer may choose a separate RF input for the monitor mode, however the separate RF input should have the same characteristics as the terrestrial RF input to the DTV. Since the remodulator outputs on the frequency of the selected RF channel, any frequency related PSIP data, which is part of the transport stream, should be ignored, if present. A source unit may already be performing some modification of the transport stream prior to output, but a source unit such as a digital VCR (DVCR) may simply record the entire transport stream of a particular input program and replay it at a later time through the remodulator. The remodulator system should accommodate both types of source units. A remodulator system, permits proper display of a program without a specific change to the PSIP content of the transport stream, thus enabling an extremely simple and low complexity source unit using a remodulator to properly interface with a DTV.
+
+## 10.2 Monitor mode conditions
+
+The following conditions are applied concerning the "monitor mode":
+
+- A unique<sup>5</sup> transport stream payload is serviced by the DTV receiver at a time. In principle, any RF channel can be monitored, and therefore this process is referred to as "***setting the DTV receiver to monitor mode N***" where *N* is the monitored RF channel number<sup>6</sup>.
+- A requirement to have a unique transport stream payload to carry a valid Program Association Table (PAT), Program Map Table (PMT), and PSIP information
+
+<sup>5</sup> Unique means that there is no need to compose aggregated channel maps for devices connected to the DTV unit since each unit is serviced one at a time.
+
+<sup>6</sup> A statement such as "tune to channel 3 for VCR operation" is no longer valid in DTV. Instead, the concept of monitor mode *N* permits similar functionality. Future digital VCR manuals may carry a statement like "set your DTV to monitor mode 3 for VCR operation".
+
+- The DTV receiver relies on PSIP data to identify the virtual channels present in the transport stream. The channel map in PSIP may be a Terrestrial Virtual Channel Table (TVCT) or a Cable Virtual Channel Table (CVCT) and receivers should be prepared to understand both<sup>7</sup>.
+- In monitor mode, there may be one or more virtual channels in the monitored transport stream and the DTV receiver may use software and on-screen menus to provide navigation and/or option selection for display or for other use.
+
+## 10.3 Monitor mode practices
+
+Based on the monitor mode conditions, the following practices are established to engineer DTV receivers capable of utilizing RF unidirectional interfacing:
+
+- The channel mapping described by PSIP defines the use of virtual channels identified by their major and minor numbers. These numbers are, in general, independent of the actual RF channel that carries the data payload. For this reason, direct tuning to an RF channel in digital television is not recommended. Therefore, standard navigation and access devices (such as remote control units, on-screen menus, or buttons on the DTV receiver) for DTV receivers should be engineered with special controls to switch operation to **monitor mode N**.
+- In monitor mode, the channel mapping, via the Virtual Channel Table (VCT), and its parameters may change completely at a given time. For example, these changes will occur when a recorded segment in a digital VCR follows another segment with different channels and programs. Accordingly, the TSID of the monitored transport stream will also change with different recording segments. In normal DTV operation, the TSID for a given transport stream does not change, therefore DTV receivers should be engineered to operate under variable conditions for the monitoring mode.
+- In the VCT, some fields are no longer relevant for the operation of a DTV receiver in monitor mode. The fields that should be ignored include, but are not limited to the following: the carrier frequency, the modulation mode, the path-select field, and the out-of-band field.
+- In monitor mode, the major and minor numbers, as well as the short and extended channel names may be used to provide navigation for services carried within the monitored transport stream. In the case of digital VCRs, major and minor channel numbers also give reference to the original channels from which programs were recorded.
+- All time of day clock references explicitly or implicitly<sup>8</sup> defined in PSIP tables obtained from monitored transport streams should be considered relative to decoded System Time Tables (STT) rather than the local clock of the DTV receiver.
+- The set of tables identified as EIT-0 give necessary program guide information about services found in the monitored transport stream. Future Event Information Tables (EIT) (EIT-1 to EIT-127), although still valid and applicable, should be considered mostly in an informative sense since, according to the practice of bullet 2 described above, there is no guarantee of the constancy of the transport stream.
+
+<sup>7</sup> The most important difference is the location of audiovisual PIDs. For a TVCT, these are carried as part of the TVCT within the service\_location\_descriptor, while for a CVCT these are entries listed in the PMT.
+
+<sup>8</sup> An explicit time reference in PSIP is, for example, the start time field for events in the EIT. An implicit time reference is the definition of the time segment for which an EIT is applicable.
+
+- When navigating the transport stream in monitor mode, PSIP may identify programs that are not in the current transport stream. Accessing such channels is beyond the scope of this Recommendation. The transport stream ID (TSID) can be used to make this distinction. Virtual channels with channel\_TSID values different than that indicated in the transport\_stream\_ID field of the virtual channel table (VCT) may be ignored.
+
+# 11 Measurement
+
+Measurement of the values specified herein should be with respect to an impedance of 75 ohms  $\pm 1\%$ . This tolerance has no other applicability.
+
+# Bibliography
+
+ATSC Standard A/54 (1995), *Guide to the Use of the ATSC Digital Television Standard*.
+
+ATSC Standard A/64 (1997), *Transmission Measurement and Compliance for Digital Television*.
+
+ATSC Standard A/65 (1997), *Program and System Information Protocol for Terrestrial Broadcast and Cable*.
+
+EIA-761-A (1998), *DTV Remodulator Specification with Enhanced OSD Capability*.
+
+EIA-799 (1999), *On-Screen Display Specification*.
+
+EIA CEB5 (1998), *Recommended Practice for DTV Receiver "Monitor" Mode Capability*.
+
+ITU-T H.222.0 (2000) | ISO/IEC 13818-1:2000, *Information Technology – Generic coding of moving pictures and associated audio information: Systems*.
+
+# **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                                                                                       |
+| <b>Series G</b> | <b>Transmission systems and media, digital systems and networks</b>                                                            |
+| 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
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+
+
+![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**
+
+**J.16**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**TELEVISION AND SOUND TRANSMISSION**
+
+---
+
+**MEASUREMENT OF WEIGHTED NOISE  
+IN SOUND - PROGRAMME CIRCUITS**
+
+**ITU-T Recommendation J.16**
+
+(Extract from the *Blue Book*)
+
+---
+
+# NOTES
+
+1 ITU-T Recommendation J.16 was published in Fascicle III.6 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.
+
+# **MEASUREMENT OF WEIGHTED NOISE IN SOUND-PROGRAMME CIRCUITS**
+
+*(Geneva, 1972; amended at Geneva, 1976 and 1980)*
+
+The noise objectives for sound-programme circuits are defined in terms of psophometrically weighted noise power levels at a zero relative level point. Psophometric weighting is used to ensure that the objectives and the results of measurements are directly related to the disturbing effect of the noise on the human ear. The psophometric weighting for sound-programme circuits consists of two operations:
+
+- a frequency-dependent weighting of the noise signal, and
+- a weighting of the time function of the noise signal to take account of the disturbing effect of noise peaks.
+
+To achieve results which are comparable, it is recommended that for the measurement of noise in sound-programme circuits, a measuring set be used which conforms to the characteristics laid down in CCIR Recommendation 468 which is reproduced at the end of this Recommendation.
+
+Annex A gives symbols and definitions used in noise measurements.
+
+## **ANNEX A**
+
+(to Recommendation J.16)
+
+### **Symbols and definitions used in noise measurements**
+
+A clear distinction should be made between measurements performed with equipment conforming to the Recommendation cited in [1] and those with equipment conforming to CCIR Recommendation 468.
+
+It is recommended that the definitions and symbols in Table A-1/J.16 be used.
+
+TABLE A-1/J.16
+
+### **Definitions and symbols for the specification of noise measured on sound-programme circuits**
+
+| Definitions                                                                                                                                                                   | Symbols |
+|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------|
+| Unweighted noise level, measured with a quasi-peak measuring instrument complying with CCIR Recommendation 468 and referred to a point of zero relative sound-programme level | dBq0s   |
+| Weighted noise level, measured with a quasi-peak measuring instrument complying with CCIR Recommendation 468 and referred to a point of zero relative sound-programme level   | dBq0ps  |
+
+### **Reference**
+
+- [1] CCITT Recommendation *Psophometers (apparatus for the objective measurement of circuit noise)*, Green Book, Vol. V, Rec. P.53, Part B, ITU, Geneva, 1973.
+
+# **MEASUREMENT OF AUDIO-FREQUENCY NOISE VOLTAGE LEVEL IN SOUND BROADCASTING**
+
+(Question 50/10)
+
+(1970 – 1974 – 1978 – 1982 – 1986)
+
+The CCIR,
+
+## CONSIDERING
+
+- (a) that it is desirable to standardize the methods of measurement of audio-frequency noise in broadcasting, in sound-recording systems and on sound-programme circuits;
+- (b) that such measurements of noise should provide satisfactory agreement with subjective assessments,
+
+# UNANIMOUSLY RECOMMENDS
+
+that the noise voltage level be measured in a quasi-peak and weighted manner, using the measurement system defined below:
+
+## **1. Weighting network**
+
+The nominal response curve of the weighting network is given in Fig. 1 b which is the theoretical response of the passive network shown in Fig. 1 a. Table I gives the values of this response at various frequencies.
+
+The permissible differences between this nominal curve and the response curve of the measuring equipment, comprising the amplifier and the network, are shown in the last column of Table I and in Fig. 2.
+
+*Note 1.* – When a weighting filter conforming to § 1 is used to measure audio-frequency noise, the measuring device should be a quasi-peak meter conforming to § 2. Indeed, the use of any other meter (e.g. an r.m.s. meter) for such a measurement would lead to figures for the signal-to-noise ratio that are not directly comparable with those obtained by using the characteristics that are described in the present Recommendation.
+
+*Note 2.* – The whole instrument is calibrated at 1 kHz (see § 2.6).
+
+![Circuit diagram of a passive weighting network (Figure 1a). It consists of a 600 Ω resistor in series with a network of inductors and capacitors, followed by an amplifier with an input impedance Z = 600 Ω. The components are: a 600 Ω resistor in series with a 12.88 mH inductor; a 13.85 nF capacitor in shunt; a 26.82 nF capacitor in shunt; a 33.06 nF capacitor in series; a 9.21 nF capacitor in shunt; a 26.49 mH inductor in series; a 31.47 nF capacitor in shunt; and finally an amplifier with Z = 600 Ω input impedance. The diagram is labeled CCITT-15680.](86f61404a19a384d06a7b0b2c4e6937a_img.jpg)
+
+Circuit diagram of a passive weighting network (Figure 1a). It consists of a 600 Ω resistor in series with a network of inductors and capacitors, followed by an amplifier with an input impedance Z = 600 Ω. The components are: a 600 Ω resistor in series with a 12.88 mH inductor; a 13.85 nF capacitor in shunt; a 26.82 nF capacitor in shunt; a 33.06 nF capacitor in series; a 9.21 nF capacitor in shunt; a 26.49 mH inductor in series; a 31.47 nF capacitor in shunt; and finally an amplifier with Z = 600 Ω input impedance. The diagram is labeled CCITT-15680.
+
+FIGURE 1 a — *Weighting network, simple form*
+
+(A constant-resistance realization is described in Annex I)
+
+(A tolerance of at most 1% on component values and a *Q*-factor of at least 200 at 10 000 Hz are sufficient to meet the tolerances given in Table I.)  
+ (The difference between the responses at 1000 Hz and 6300 Hz may be adjusted more precisely by a small adjustment of the 33.06 nF capacitor, or by a different approach using an active filter [CCIR, 1982-86a])
+
+![Frequency response graph showing Response (dB) vs Frequency (Hz) on a semi-logarithmic scale. The curve rises from -30 dB at 30 Hz to a peak of 12 dB at 8 kHz, then falls sharply to -48 dB at 20 kHz. CCITT - 15680 label is present.](de6e8b740c69dac308cce9edfec3eff4_img.jpg)
+
+The graph shows the frequency response of a weighting network. The vertical axis represents 'Response (dB)' from -48 to 12 in 4 dB increments. The horizontal axis represents 'Frequency (Hz)' on a logarithmic scale with major markers at 2, 5, 10<sup>2</sup>, 2, 5, 10<sup>3</sup>, 2, 5, 10<sup>4</sup>, 2, 5. A curve with data points shows a rise from -30 dB at 30 Hz to a peak of 12 dB at 8 kHz, followed by a sharp decline to -48 dB at 20 kHz. The label 'CCITT - 15680' is located at the bottom right of the graph area.
+
+| Frequency (Hz) | Response (dB) |
+|----------------|---------------|
+| 30             | -30           |
+| 40             | -26           |
+| 50             | -22           |
+| 60             | -18           |
+| 80             | -14           |
+| 100            | -10           |
+| 150            | -6            |
+| 200            | -2            |
+| 300            | 0             |
+| 400            | 2             |
+| 500            | 4             |
+| 700            | 6             |
+| 1000           | 8             |
+| 1500           | 10            |
+| 2000           | 11            |
+| 3000           | 12            |
+| 4000           | 12            |
+| 5000           | 12            |
+| 6000           | 12            |
+| 7000           | 12            |
+| 8000           | 12            |
+| 9000           | 11            |
+| 10000          | 10            |
+| 12000          | 0             |
+| 14000          | -6            |
+| 16000          | -12           |
+| 18000          | -22           |
+| 20000          | -48           |
+
+Frequency response graph showing Response (dB) vs Frequency (Hz) on a semi-logarithmic scale. The curve rises from -30 dB at 30 Hz to a peak of 12 dB at 8 kHz, then falls sharply to -48 dB at 20 kHz. CCITT - 15680 label is present.
+
+FIGURE 1b – Frequency response of the weighting network shown in Fig. 1 a
+
+TABLE I
+
+| Frequency (Hz) | Response (dB) | Proposed tolerance (dB)                           |
+|----------------|---------------|---------------------------------------------------|
+| 31.5           | -29.9         | $\pm 2.0$                                         |
+| 63             | -23.9         | $\pm 1.4^{(1)}$                                   |
+| 100            | -19.8         | $\pm 1.0$                                         |
+| 200            | -13.8         | $\pm 0.85^{(1)}$                                  |
+| 400            | -7.8          | $\pm 0.7^{(1)}$                                   |
+| 800            | -1.9          | $\pm 0.55^{(1)}$                                  |
+| 1 000          | 0             | $\pm 0.5$                                         |
+| 2 000          | +5.6          | $\pm 0.5$                                         |
+| 3 150          | +9.0          | $\pm 0.5^{(1)}$                                   |
+| 4 000          | +10.5         | $\pm 0.5^{(1)}$                                   |
+| 5 000          | +11.7         | $\pm 0.5$                                         |
+| 6 300          | +12.2         | 0                                                 |
+| 7 100          | +12.0         | $\pm 0.2^{(1)}$                                   |
+| 8 000          | +11.4         | $\pm 0.4^{(1)}$                                   |
+| 9 000          | +10.1         | $\pm 0.6^{(1)}$                                   |
+| 10 000         | +8.1          | $\pm 0.8^{(1)}$                                   |
+| 12 500         | 0             | $\pm 1.2^{(1)}$                                   |
+| 14 000         | -5.3          | $\pm 1.4^{(1)}$                                   |
+| 16 000         | -11.7         | $\pm 1.6^{(1)}$                                   |
+| 20 000         | -22.2         | $\pm 2.0$                                         |
+| 31 500         | -42.7         | $\begin{cases} +2.8^{(1)} \\ -\infty \end{cases}$ |
+
+1) This tolerance is obtained by a linear interpolation on a logarithmic graph on the basis of values specified for the frequencies used to define the mask, i.e. 31.5, 100, 1000, 5000, 6300 and 20 000 Hz.
+
+![Figure 2: A log-log plot showing the maximum tolerances for the frequency response of the weighting network and the amplifier. The x-axis is Frequency (Hz) from 2 to 5, with major ticks at 10^2, 10^3, and 10^4. The y-axis is Tolerance (dB) from -8 to 4, with major ticks every 2 dB. Two lines are plotted: an upper line representing the upper tolerance limit and a lower line representing the lower tolerance limit. The upper line starts at 2 dB at 20 Hz, decreases to 0.5 dB at 100 Hz, remains flat until 5000 Hz, then rises to 3 dB at 50000 Hz. The lower line starts at -2 dB at 20 Hz, increases to -1 dB at 100 Hz, remains flat until 5000 Hz, then drops to -2 dB at 20000 Hz and remains flat until 50000 Hz.](4086a572c080354982c11f1de4d6921d_img.jpg)
+
+| Frequency (Hz) | Upper Tolerance (dB) | Lower Tolerance (dB) |
+|----------------|----------------------|----------------------|
+| 20             | 2                    | -2                   |
+| 100            | 0.5                  | -1                   |
+| 1000           | 0.5                  | -1                   |
+| 5000           | 0.5                  | -1                   |
+| 20000          | 2                    | -2                   |
+| 50000          | 3                    | -2                   |
+
+Figure 2: A log-log plot showing the maximum tolerances for the frequency response of the weighting network and the amplifier. The x-axis is Frequency (Hz) from 2 to 5, with major ticks at 10^2, 10^3, and 10^4. The y-axis is Tolerance (dB) from -8 to 4, with major ticks every 2 dB. Two lines are plotted: an upper line representing the upper tolerance limit and a lower line representing the lower tolerance limit. The upper line starts at 2 dB at 20 Hz, decreases to 0.5 dB at 100 Hz, remains flat until 5000 Hz, then rises to 3 dB at 50000 Hz. The lower line starts at -2 dB at 20 Hz, increases to -1 dB at 100 Hz, remains flat until 5000 Hz, then drops to -2 dB at 20000 Hz and remains flat until 50000 Hz.
+
+FIGURE 2 — *Maximum tolerances for the frequency response of the weighting network and the amplifier*
+
+## 2. Characteristics of the measuring device
+
+A quasi-peak value method of measurement shall be used. The required dynamic performance of the measuring set may be realized in a variety of ways (see Note). It is defined in the following sections. Tests of the measuring equipment, except those for § 2.4, should be made through the weighting network.
+
+*Note* — After full wave rectification of the input signal, a possible arrangement would consist of two peak rectifier circuits of different time constants connected in tandem [CCIR, 1974-78].
+
+### 2.1 *Dynamic characteristic in response to single tone-bursts*
+
+#### *Method of measurement*
+
+Single bursts of 5 kHz tone are applied to the input at an amplitude such that the steady signal would give a reading of 80% of full scale. The burst should start at the zero-crossing of the 5 kHz tone and should consist of an integral number of full periods. The limits of reading corresponding to each duration of tone burst are given in Table II.
+
+The tests should be performed both without adjustment of the attenuators, the readings being observed directly from the instrument scale, and also with the attenuators adjusted for each burst duration to maintain the reading as nearly constant at 80% of full scale as the attenuator steps will permit.
+
+TABLE II
+
+| Burst duration<br>(ms)                                         | 1 <sup>(1)</sup> | 2              | 5           | 10          | 20          | 50          | 100         | 200         |
+|----------------------------------------------------------------|------------------|----------------|-------------|-------------|-------------|-------------|-------------|-------------|
+| Amplitude reference<br>steady signal<br>reading<br>(%)<br>(dB) | 17.0<br>– 15.4   | 26.6<br>– 11.5 | 40<br>– 8.0 | 48<br>– 6.4 | 52<br>– 5.7 | 59<br>– 4.6 | 68<br>– 3.3 | 80<br>– 1.9 |
+| Limiting values:                                               |                  |                |             |             |             |             |             |             |
+| – lower limit<br>(%)<br>(dB)                                   | 13.5<br>– 17.4   | 22.4<br>– 13.0 | 34<br>– 9.3 | 41<br>– 7.7 | 44<br>– 7.1 | 50<br>– 6.0 | 58<br>– 4.7 | 68<br>– 3.3 |
+| – upper limit<br>(%)<br>(dB)                                   | 21.4<br>– 13.4   | 31.6<br>– 10.0 | 46<br>– 6.6 | 55<br>– 5.2 | 60<br>– 4.4 | 68<br>– 3.3 | 78<br>– 2.2 | 92<br>– 0.7 |
+
+<sup>(1)</sup> The Administration of the USSR intends to use burst durations  $\geq 5$  ms.
+
+### 2.2 Dynamic characteristic in response to repetitive tone-bursts
+
+#### Method of measurement
+
+A series of 5 ms bursts of 5 kHz tone starting at zero-crossing is applied to the input at an amplitude such that the steady signal would give a reading of 80% of full scale. The limits of the reading corresponding to each repetition frequency are given in Table III.
+
+The tests should be performed without adjustment of the attenuators but the characteristic should be within tolerance on all ranges.
+
+TABLE III
+
+| Number of bursts per second                                 | 2           | 10          | 100          |
+|-------------------------------------------------------------|-------------|-------------|--------------|
+| Amplitude reference<br>steady signal reading<br>(%)<br>(dB) | 48<br>– 6.4 | 77<br>– 2.3 | 97<br>– 0.25 |
+| Limiting values:                                            |             |             |              |
+| – lower limit<br>(%)<br>(dB)                                | 43<br>– 7.3 | 72<br>– 2.9 | 94<br>– 0.5  |
+| – upper limit<br>(%)<br>(dB)                                | 53<br>– 5.5 | 82<br>– 1.7 | 100<br>– 0.0 |
+
+### 2.3 *Overload characteristics*
+
+The overload capacity of the measuring set should be more than 20 dB with respect to the maximum indication of the scale at all settings of the attenuators. The term “overload capacity” refers both to absence of clipping in linear stages and to retention of the law of any logarithmic or similar stage which may be incorporated.
+
+#### *Method of measurement*
+
+Isolated 5 kHz tone-bursts of 0.6 ms duration starting at zero-crossing are applied to the input at an amplitude giving full scale reading using the most sensitive range of the instrument. The amplitude of the tone-bursts is decreased in steps by a total of 20 dB while the readings are observed to check that they decrease by corresponding steps within an overall tolerance of  $\pm 1$  dB. The test is repeated for each range.
+
+### 2.4 *Reversibility error*
+
+The difference in reading when the polarity of an asymmetrical signal is reversed shall not be greater than 0.5 dB.
+
+#### *Method of measurement*
+
+1 ms rectangular d.c. pulses with a pulse repetition rate of 100 pulses per second or less are applied to the input in the unweighted mode, at an amplitude giving an indication of 80% of full scale. The polarity of the input signal is reversed and the difference in indication is noted.
+
+### 2.5 *Overswing*
+
+The reading device shall be free from excessive overswing.
+
+#### *Method of measurement*
+
+1 kHz tone is applied to the input at an amplitude giving a steady reading of 0.775 V or 0 dB (see § 2.6). When this signal is suddenly applied there shall be less than 0.3 dB momentary excess reading.
+
+### 2.6 *Calibration*
+
+The instrument shall be calibrated such that a steady input signal of 1 kHz sine-wave at 0.775 V r.m.s., having less than 1% total harmonic distortion, shall give a reading of 0.775 V, 0 dB. The scale should have a calibrated range of at least 20 dB with the indication corresponding to 0.775 V (or 0 dB) between 2 and 10 dB below full scale.
+
+### 2.7 *Input impedance*
+
+The instrument should have an input impedance  $\geq 20$  k $\Omega$  and if an input termination is provided then this should be  $600 \Omega \pm 1\%$ .
+
+## 3. **Presentation of results**
+
+Noise voltage levels measured according to this Recommendation are expressed in units of dBbps.
+
+*Note 1* – If, for technical reasons, it is desirable to measure unweighted noise, the method described in Annex II should be used.
+
+*Note 2* – The influence of the weighting network on readings obtained with different spectra of random noise is discussed in Report 496.
+
+## REFERENCES
+
+## *CCIR Documents*
+
+[1974-78]: 10/28 (United Kingdom).
+
+[1982-86]: a. 10/248 (Australia).
+
+## BIBLIOGRAPHY
+
+BBC [1968] Research Department Report No. EL-17. The assessment of noise in audio-frequency circuits.
+
+DEUTSCHE NORMEN DIN 45 405.
+
+STEFFEN, E. [1972] Untersuchungen zur Geräuschspannungsmessung (Investigations into the measurement of noise voltage).  
+*Techn. Mitt. RFZ*, Heft 3.
+
+WILMS, H. A. O. [December, 1970] Subjective or psophometric audio noise measurement: A review of standards. *J. Audio Eng. Soc.*, Vol. 18, 6.
+
+*CCIR Documents*
+
+[1978-82]: 10/9 (EBU); 10/31 (L M Ericsson); 10/38 (OIRT); 10/225 (German Democratic Republic).
+
+## ANNEX I
+
+### CONSTANT RESISTANCE REALIZATION OF WEIGHTING NETWORK
+
+![Circuit diagram of a constant resistance realization of a weighting network. The diagram shows an input section with a voltage source, resistors R0 and 1/2 R0, capacitors 2C1, and inductors L1A and L1B. A switch S connects the input to a balanced/unbalanced section containing a transformer with windings L2A, L2B, L3A+B, and L3C. The output section includes resistors R1, R2, R3, capacitors C2 through C7, and inductors L4 through L7, terminating in a load Z = 600 Ω. The diagram is labeled CCITT-85730.](1eadbbe42cfcac5c0023577110aec5e3_img.jpg)
+
+Circuit diagram of a constant resistance realization of a weighting network. The diagram shows an input section with a voltage source, resistors R0 and 1/2 R0, capacitors 2C1, and inductors L1A and L1B. A switch S connects the input to a balanced/unbalanced section containing a transformer with windings L2A, L2B, L3A+B, and L3C. The output section includes resistors R1, R2, R3, capacitors C2 through C7, and inductors L4 through L7, terminating in a load Z = 600 Ω. The diagram is labeled CCITT-85730.
+
+FIGURE 3
+
+Constant resistance realization of weighting network
+
+| R (Ω)                  | C (nF)                 | L (mH)                                                                                                                           |
+|------------------------|------------------------|----------------------------------------------------------------------------------------------------------------------------------|
+| R <sub>0</sub> : 600   | 2C <sub>1</sub> : 83.7 | L <sub>1</sub> : 12.70 (for both windings in series)                                                                             |
+| ½ R <sub>0</sub> : 300 | C <sub>2</sub> : 35.28 | L <sub>2</sub> : 15.06 (for each of two windings separated by electrostatic shield)                                              |
+| R <sub>1</sub> : 912   | C <sub>3</sub> : 38.4  | L <sub>3A+B</sub> : 16.73 (two equal windings in series)                                                                         |
+| R <sub>2</sub> : 3340  | C <sub>4</sub> : 7.99  | L <sub>3C</sub> : 4.18 (one winding, turns half L <sub>3A+B</sub> , can have large d.c. resistance, absorbed in R <sub>3</sub> ) |
+| R <sub>3</sub> : 941   | C <sub>5</sub> : 23.8  | L <sub>4</sub> : 20.1 (can have large d.c. resistance, absorbed in R <sub>3</sub> )                                              |
+|                        | C <sub>6</sub> : 13.94 | L <sub>5</sub> : 31.5 (with tap 20.1 at 0.798 of total turns)                                                                    |
+|                        | C <sub>7</sub> : 35.4  | L <sub>6</sub> : 13.29                                                                                                           |
+|                        |                        | L <sub>7</sub> : 8.00                                                                                                            |
+
+A: unbalanced  
+S: balanced
+
+### BIBLIOGRAPHY
+
+AUSTRALIAN BROADCASTING COMMISSION Engineering Development Report No. 106 – Constant resistance realization of CCIR noise weighting network, Recommendation 468.
+
+## ANNEX II
+
+### UNWEIGHTED MEASUREMENT
+
+It is recognized that unweighted measurements outside the scope of this Recommendation may be required for specific purposes. A standard response for unweighted measurements is included here for guidance.
+
+#### Frequency response
+
+The frequency response shall be within the limits given in Fig. 4.
+
+This response serves to standardize the measurement and ensure consistent readings of noise distributed across the useful spectrum. When out-of-band signals, e.g. carrier leaks, are present at a sufficient amplitude, they may produce readings that are inconsistent between measuring equipments whose responses are different but still fall within the tolerance template of Fig. 4.
+
+![Figure 4: Frequency response graph showing Level (dB) vs Frequency (Hz and kHz). The graph shows a flat response between 22.4 Hz and 22.4 kHz with a tolerance of ±0.5 dB. The response rolls off at 12 dB/octave below 22.4 Hz and 18 dB/octave above 22.4 kHz.](b712e7522f1bb7135730c7d1abb46d43_img.jpg)
+
+The graph shows the frequency response in dB versus frequency. The y-axis is labeled 'Level (dB)' and ranges from -70 to 10. The x-axis is labeled 'Frequency (Hz)' and 'Frequency (kHz)'. The frequency scale is logarithmic, with major markings at 1, 2, 5, 10, 2, 5, 10<sup>2</sup>, 2, 5, 10<sup>3</sup>, 2, 5, 10<sup>4</sup>, 2, 5, 10<sup>5</sup> Hz, and 22.4 Hz, 31.5 Hz, 16 kHz, and 22.4 kHz. The response is flat at 0 dB between 22.4 Hz and 22.4 kHz, with a tolerance of ±0.5 dB. Below 22.4 Hz, the response rolls off at 12 dB/octave. Above 22.4 kHz, the response rolls off at 18 dB/octave.
+
+Figure 4: Frequency response graph showing Level (dB) vs Frequency (Hz and kHz). The graph shows a flat response between 22.4 Hz and 22.4 kHz with a tolerance of ±0.5 dB. The response rolls off at 12 dB/octave below 22.4 Hz and 18 dB/octave above 22.4 kHz.
+
+FIGURE 4
+
+## BIBLIOGRAPHY
+
+CCIR Documents
+
+[1978-82]: 10/76 (CMTT/14) (Canada).
\ No newline at end of file
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+
+
+International Telecommunication Union
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.170**
+
+(11/2005)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+IPCablecom
+
+---
+
+**IPCablecom security specification**
+
+Recommendation ITU-T J.170
+
+![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a globe with a red lightning bolt striking it, symbolizing global communication. The text "ITU" is prominently displayed in blue, with "International Telecommunication Union" written in smaller blue text to the right.
+
+ITU logo
+
+
+
+# **Recommendation ITU-T J.170**
+
+# **IPCablecom security specification**
+
+# **Summary**
+
+This Recommendation defines authentication, access control, signalling and media content integrity, confidentiality, and non-repudiation security services for each of the network element interfaces.
+
+IPCablecom security spans the entire IPCablecom architecture. The IPCablecom architectural framework Recommendation (ITU-T Rec. J.160) defines the overall IPCablecom architecture, as well as the system elements, interfaces, and functional requirements for the entire IPCablecom network.
+
+## **Source**
+
+Recommendation ITU-T J.170 was approved on 29 November 2005 by ITU-T Study Group 9 (2005-2008) under Recommendation ITU-T A.8 procedures.
+
+# 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2010
+
+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 and introduction .....                       | 1   |
+| 1.1 | Scope .....                                        | 1   |
+| 1.2 | Introduction .....                                 | 1   |
+| 2   | References.....                                    | 2   |
+| 2.1 | Normative references.....                          | 2   |
+| 2.2 | Informative references.....                        | 3   |
+| 3   | Terms and definitions .....                        | 4   |
+| 4   | Abbreviations, acronyms and conventions .....      | 5   |
+| 4.1 | Abbreviations and acronyms .....                   | 5   |
+| 4.2 | Conventions .....                                  | 8   |
+| 5   | Architectural overview of IPCablecom security..... | 9   |
+| 5.1 | IPCablecom reference architecture.....             | 9   |
+| 5.2 | Threats .....                                      | 13  |
+| 5.3 | Security architecture .....                        | 19  |
+| 6   | Security mechanisms .....                          | 26  |
+| 6.1 | IPsec .....                                        | 26  |
+| 6.2 | Internet Key Exchange (IKE).....                   | 28  |
+| 6.3 | SNMPv3 .....                                       | 30  |
+| 6.4 | Kerberos/PKINIT .....                              | 31  |
+| 6.5 | Kerberized key management .....                    | 55  |
+| 6.6 | End-to-end security for RTP .....                  | 76  |
+| 6.7 | End-to-end security for RTCP.....                  | 76  |
+| 6.8 | BPI+.....                                          | 77  |
+| 6.9 | TLS .....                                          | 78  |
+| 7   | Security profile .....                             | 80  |
+| 7.1 | Device and service provisioning .....              | 81  |
+| 7.2 | Quality of Service (QoS) signalling .....          | 93  |
+| 7.3 | Billing system interfaces .....                    | 95  |
+| 7.4 | Call signalling.....                               | 97  |
+| 7.5 | PSTN Gateway interface .....                       | 104 |
+| 7.6 | Media stream .....                                 | 106 |
+| 7.7 | Audio Server services.....                         | 126 |
+| 7.8 | Electronic surveillance interfaces.....            | 129 |
+| 7.9 | CMS provisioning .....                             | 133 |
+| 8   | IPCablecom certificates .....                      | 134 |
+| 8.1 | Generic structure .....                            | 134 |
+| 8.2 | Certificate trust hierarchy .....                  | 135 |
+
+|                                                                           | Page |
+|---------------------------------------------------------------------------|------|
+| 9 Cryptographic algorithms .....                                          | 145  |
+| 9.1 AES.....                                                              | 145  |
+| 9.2 DES.....                                                              | 145  |
+| 9.3 Block termination .....                                               | 146  |
+| 9.4 RSA signature.....                                                    | 151  |
+| 9.5 HMAC-SHA-1 .....                                                      | 151  |
+| 9.6 Key derivation .....                                                  | 151  |
+| 9.7 The MMH-MAC .....                                                     | 152  |
+| 9.8 Random number generation .....                                        | 154  |
+| 10 Physical security .....                                                | 154  |
+| 10.1 Protection for MTA key storage.....                                  | 154  |
+| 10.2 MTA key encapsulation .....                                          | 157  |
+| 11 Secure software upgrade.....                                           | 157  |
+| Annex A – Oakley groups.....                                              | 158  |
+| Annex B – Kerberos Network Authentication Service .....                   | 159  |
+| Annex C – PKINIT specification.....                                       | 159  |
+| Appendix I – IPCablecom administration guidelines and best practices..... | 160  |
+| I.1 Routine CMS service key refresh.....                                  | 160  |
+| Appendix II – Example of MMH algorithm implementation.....                | 161  |
+
+# IPCablecom security specification
+
+# 1 Scope and introduction
+
+## 1.1 Scope
+
+Authentication, access control, signalling and media content integrity, confidentiality, and non-repudiation security services must be provided as defined herein for each of the network element interfaces.
+
+IPCablecom security spans the entire IPCablecom architecture. The IPCablecom architectural framework Recommendation (ITU-T Rec. J.160) defines the overall IPCablecom architecture, as well as the system elements, interfaces, and functional requirements for the entire IPCablecom network.
+
+## 1.2 Introduction
+
+### 1.2.1 Goals
+
+This Recommendation describes the security relationships between the elements on the IPCablecom network. The general goals of this IPCablecom network security Recommendation and any implementations that encompass the requirements defined herein should be:
+
+- **Secure network communications:** The IPCablecom network security must define a security architecture, methods, algorithms and protocols that meet the stated security service requirement. All media packets and all sensitive signalling communication across the network must be safe from eavesdropping. Unauthorized message modification, insertion, deletion and replays anywhere in the network must be easily detectable and must not affect proper network operation.
+- **Reasonable cost:** The IPCablecom network security must define security methods, algorithms and protocols that meet the stated security service requirements such that a reasonable implementation can be manifested with reasonable cost and implementation complexity.
+- **Network element interoperability:** All of the security services for any of the IPCablecom network elements must interoperate with the security services for all of the other IPCablecom network elements. Multiple vendors may implement each of the IPCablecom network elements as well as multiple vendors for a single IPCablecom network element.
+- **Extensibility:** The IPCablecom security architecture, methods, algorithms and protocols must provide a framework into which new security methods and algorithms may be incorporated as necessary.
+
+### 1.2.2 Assumptions
+
+The following assumptions are made relative to the current scope of the IPCablecom security Recommendation:
+
+- Embedded Media Terminal Adaptors (MTAs) are within the current scope. Stand-alone MTAs will be addressed in later phases and security issues for stand-alone MTAs are thus for future study.
+- Network Call Signalling (NCS) is the only call signalling method, on the access network, addressed in this Recommendation.
+- This version of the IPCablecom security Recommendation specifies security for a single administrative domain and the communications between domains.
+
+- Security for chained RADIUS servers is not currently in the scope.
+
+This Recommendation also does not include requirements for associated security operational issues (e.g., site security), back-office or inter/intra back-office security, service authorization policies or secure database handling. Record Keeping Servers (RKS), Network Management Systems, File Transfer Protocol (FTP) servers and Dynamic Host Configuration Protocol (DHCP) servers are all considered to be unique to any service provider's implementation and are beyond the scope of this Recommendation.
+
+# 2 References
+
+## 2.1 Normative 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.
+
+- Recommendation ITU-T J.112 (1998), *Transmission systems for interactive cable television services*.
+- Recommendation ITU-T J.122 (2002), *Second-generation transmission systems for interactive cable television services – IP cable modems*.
+- Recommendation ITU-T J.125 (2004), *Link privacy for cable modem implementations*.
+- Recommendation ITU-T J.126 (2004), *Embedded Cable Modem device specification*.
+- Recommendation ITU-T J.162 (2005), *Network call signalling protocol for the delivery of time-critical services over cable television networks using cable modems*.
+- Recommendation ITU-T J.166 (2005), *IPCablecom Management Information Base (MIB) framework*.
+- Recommendation ITU-T J.167 (2005), *Media terminal adapter (MTA) device provisioning requirements for the delivery of real-time services over cable television networks using cable modems*.
+- Recommendation ITU-T X.509 (2000) | ISO/IEC 9594-8:2001, *Information technology – Open Systems Interconnection – The Directory: Public-key and attribute certificate frameworks*.
+- Recommendation ITU-T X.690 (2002) | ISO/IEC 8825-1:2002, *Information technology – ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER)*.
+- IETF RFC 1889 (1996), *RTP: A Transport Protocol for Real-Time Applications*.
+- IETF RFC 1890 (1996), *RTP Profile for Audio and Video Conferences with Minimal Control*.
+- IETF RFC 2104 (1997), *HMAC: Keyed-Hashing for Message Authentication*.
+- IETF RFC 2246 (1999), *The TLS Protocol Version 1.0*.
+- IETF RFC 2367 (1998), *PF\_KEY Key Management API, Version 2*.
+- IETF RFC 2401 (1998), *Security Architecture for the Internet Protocol*.
+
+- IETF RFC 2403 (1998), *The Use of HMAC-MD5-96 within ESP and AH.*
+- IETF RFC 2404 (1998), *The Use of HMAC-SHA-1-96 within ESP and AH.*
+- IETF RFC 2406 (1998), *IP Encapsulating Security Payload (ESP).*
+- IETF RFC 2407 (1998), *The Internet IP Security Domain of Interpretation for ISAKMP.*
+- IETF RFC 2409 (1998), *The Internet Key Exchange (IKE).*
+- IETF RFC 2437 (1998), *PKCS#1: RSA Cryptography Specification Version 2.0.*
+- IETF RFC 2451 (1998), *The ESP CBC-Mode Cipher Algorithms.*
+- IETF RFC 2459 (1999), *Internet X.509 Public Key Infrastructure Certificate and CRL Profile.*
+- IETF RFC 2630 (1999), *Cryptographic Message Syntax.*
+- IETF RFC 3261 (2002), *SIP: Session Initiation Protocol.*
+- IETF RFC 3412 (2002), *Message Processing and Dispatching for the Simple Network Management Protocol (SNMP).*
+- IETF RFC 3414 (2002), *User-based Security Model (USM) for Version 3 of the Simple Network Management Protocol (SNMPv3).*
+- IETF RFC 4120 (2005), *The Kerberos Network Authentication Service (V5).*
+- IETF RFC 4556 (2006), *Public Key Cryptography for Initial Authentication in Kerberos (PKINIT).*
+- FIPS PUB 81 (1980), *DES Modes of Operation.*
+- FIPS PUB 180-1 (1995), *Secure Hash Algorithm (SHS).*
+- FIPS PUB 197 (2001), *Advanced Encryption Standard (AES).*
+
+## 2.2 Informative references
+
+- Recommendation ITU-T J.160 (2005), *Architectural framework for the delivery of time-critical services over cable television networks using cable modems.*
+- Recommendation ITU-T J.161 (2001), *Audio codec requirements for the provision of bidirectional audio service over cable television networks using cable modems.*
+- Recommendation ITU-T J.163 (2005), *Dynamic quality of service for the provision of real-time services over cable television networks using cable modems.*
+- Recommendation ITU-T J.164 (2005), *Event message requirements for the support of real-time services over cable television networks using cable modems.*
+- Recommendation ITU-T J.171.x (2005), *IPCablecom Trunking Gateway Control Protocol (TGCP).*
+- Recommendation ITU-T J.175 (2002), *Audio server protocol.*
+- Recommendation ITU-T J.178 (2005), *IPCablecom CMS to CMS signalling.*
+- FIPS PUB 140-1 (1994), *Security Requirements for Cryptographic Modules.*
+- IETF RFC 1750 (1994), *Randomness Recommendations for Security.*
+- IETF RFC 2327 (1998), *SDP: Session Description Protocol.*
+- IETF RFC 2782 (2000), *A DNS RR for specifying the location of services (DNS SRV).*
+
+- IETF RFC 3268 (2002), *Advanced Encryption Standard (AES) Ciphersuites for Transport Layer Security (TLS)*.
+- HALEVI [S.], KRAWCZYK [H.]: MMH: Software Message Authentication in the Gbit/Second Rates, *Proceedings of the 4th Workshop on Fast Software Encryption*, Vol. 1267 Springer-Verlag, pp. 172-189, 1997.
+- KILIAN [J.], ROGAWAY [P.]: How to Protect DES Against Exhaustive Key Search, *Edited version presented at Proceedings of Crypto '96*, July 1997.
+- SCHNEIER [B.]: *Applied Cryptography*, John Wiley & Sons, Inc., Second edition, 1996.
+
+# 3 Terms and definitions
+
+This Recommendation defines the following terms:
+
+**3.1 access control:** Limiting the flow of information from the resources of a system only to authorized persons, programs, processes or other system resources on a network.
+
+**3.2 audio server:** An Audio Server plays informational announcements in IPCablecom network. Media announcements are needed for communications that do not complete and to provide enhanced information services to the user. The component parts of Audio Server services are Media Players and Media Player Controllers.
+
+**3.3 authentication:** The process of verifying the claimed identity of an entity to another entity.
+
+**3.4 authenticity:** The ability to ensure that the given information is without modification or forgery and was in fact produced by the entity that claims to have given the information.
+
+**3.5 authorization:** The act of giving access to a service or device if one has the permission to have the access.
+
+**3.6 cipher:** An algorithm that transforms data between plaintext and ciphertext.
+
+**3.7 ciphersuite:** A set, which must contain both an encryption algorithm and a message authentication algorithm (e.g., a MAC or an HMAC). In general, it may also contain a key management algorithm, which does not apply in the context of IPCablecom.
+
+**3.8 confidentiality:** A way to ensure that information is not disclosed to any one other than the intended parties. Information is encrypted to provide confidentiality. Also known as privacy.
+
+**3.9 cryptanalysis:** The process of recovering the plaintext of a message or the encryption key without access to the key.
+
+**3.10 downstream:** The direction from the head-end toward the subscriber location.
+
+**3.11 encryption:** A method used to translate information in plaintext into ciphertext.
+
+**3.12 endpoint:** A Terminal, Gateway or MCU.
+
+**3.13 event message:** Message capturing a single portion of a connection.
+
+**3.14 gateway:** Devices bridging between the IPCablecom Voice Communication world and the PSTN. Examples are the Media Gateway which provides the bearer circuit interfaces to the PSTN and transcodes the media stream, and the Signalling Gateway which sends and receives circuit switched network signalling to the edge of the IPCablecom network.
+
+**3.15 header:** Protocol control information located at the beginning of a protocol data unit.
+
+**3.16 integrity:** A way to ensure that information is not modified except by those who are authorized to do so.
+
+**3.17 Kerberos:** A secret-key network authentication protocol that uses a choice of cryptographic algorithms for encryption and a centralized key database for authentication.
+
+- 3.18 key:** A mathematical value input into the selected cryptographic algorithm.
+- 3.19 key exchange:** The swapping of public keys between entities to be used to encrypt communication between the entities.
+- 3.20 key management:** The process of distributing shared symmetric keys needed to run a security protocol.
+- 3.21 non-repudiation:** The ability to prevent a sender from denying later that he or she sent a message or performed an action.
+- 3.22 privacy:** A way to ensure that information is not disclosed to any one other than the intended parties. Information is usually encrypted to provide confidentiality. Also known as "confidentiality".
+- 3.23 private key:** The key used in public key cryptography that belongs to an individual entity and must be kept secret.
+- 3.24 proxy:** A facility that indirectly provides some service or acts as a representative in delivering information thereby eliminating the need for a host to support the service.
+- 3.25 public key:** The key used in public key cryptography that belongs to an individual entity and is distributed publicly. Other entities use this key to encrypt data to be sent to the owner of the key.
+- 3.26 public key certificate:** A binding between an entity's public key and one or more attributes relating to its identity, also known as a digital certificate.
+- 3.27 public key cryptography:** A procedure that uses a pair of keys, a public key and a private key for encryption and decryption, also known as an asymmetric algorithm. A user's public key is publicly available for others to use to send a message to the owner of the key. A user's private key is kept secret and is the only key that can decrypt messages sent encrypted by the user's public key.
+- 3.28 root private key:** The private signing key of the highest-level Certification Authority. It is normally used to sign public key certificates for lower-level Certification Authorities or other entities.
+- 3.29 X.509 certificate:** A public key certificate specification developed as part of the ITU-T Rec. X.500 standards directory.
+
+# **4 Abbreviations, acronyms and conventions**
+
+## **4.1 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+- |      |                                                                                                                                                                                               |
+|------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| AES  | Advanced Encryption Standard                                                                                                                                                                  |
+| AH   | Authentication Header is an IPsec security protocol that provides message integrity for complete IP packets, including the IP header.                                                         |
+| ASD  | Application-Specific Data. An application-specific field in the IPsec header that along with the destination IP address provides a unique number for each SA.                                 |
+| BPI+ | Baseline Privacy Interface Plus is the security portion of ITU-T Rec. J.112 that runs on the MAC layer.                                                                                       |
+| CBC  | Cipher-block Chaining mode is an option in block ciphers that combine (XOR) the previous block of ciphertext with the current block of plaintext before encrypting that block of the message. |
+
+|         |                                                                                                                                                                                                                                            |
+|---------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| CA      | Certification Authority. A trusted organization that accepts certificate applications from entities, authenticates applications, issues certificates and maintains status information about certificates.                                  |
+| CA      | Call Agent. The part of the CMS that maintains the communication state, and controls the line side of the communication.                                                                                                                   |
+| CM      | Cable Modem                                                                                                                                                                                                                                |
+| CMS     | Cryptographic Message Syntax                                                                                                                                                                                                               |
+| CMS     | Call Management Server. Controls the audio connections. Also called a Call Agent in MGCP/SGCP terminology. This is one example of an Application Server.                                                                                   |
+| CMTS    | Cable Modem Termination System                                                                                                                                                                                                             |
+| CNAME   | Canonical Name                                                                                                                                                                                                                             |
+| COPS    | Common Open Policy Service                                                                                                                                                                                                                 |
+| CRL     | Certificate Revocation List                                                                                                                                                                                                                |
+| CSR     | Customer Service Record                                                                                                                                                                                                                    |
+| DES     | Data Encryption Standard                                                                                                                                                                                                                   |
+| DF      | Delivery Function                                                                                                                                                                                                                          |
+| DH      | Diffie-Hellman                                                                                                                                                                                                                             |
+| DHCP    | Dynamic Host Configuration Protocol                                                                                                                                                                                                        |
+| DNS     | Domain Name Server                                                                                                                                                                                                                         |
+| DNS SRV | A DNS RR for specifying the location of services                                                                                                                                                                                           |
+| DOCSIS  | Data-Over-Cable Service Interface Specification                                                                                                                                                                                            |
+| DQoS    | Dynamic Quality of Service                                                                                                                                                                                                                 |
+| DSCP    | DiffServ Code Point. A field in every IP packet that identifies the DiffServ Per-Hop Behavior. In IP version 4, the TOS byte is redefined to be the DSCP. In IP version 6, the Traffic Class octet is used as the DSCP. See IETF RFC 4556. |
+| DTMF    | Dual-Tone Multifrequency (tones)                                                                                                                                                                                                           |
+| ESP     | IPsec Encapsulating Security                                                                                                                                                                                                               |
+| FQDN    | Fully Qualified Domain Name. Refer to IETF RFC 821 for details.                                                                                                                                                                            |
+| GW      | Gateway                                                                                                                                                                                                                                    |
+| HFC     | Hybrid-Fibre/Coax                                                                                                                                                                                                                          |
+| HMAC    | Hashed Message Authentication Code. A message authentication algorithm, based on either SHA-1 or MD5 hash and defined in IETF RFC 2104.                                                                                                    |
+| IKE     | Internet Key Exchange is a key management mechanism used to negotiate and derive keys for SAs in IPsec.                                                                                                                                    |
+| IKE     | A notation defined to refer to the use of IKE with pre-shared keys for authentication.                                                                                                                                                     |
+| INA     | Interactive Network Adapter                                                                                                                                                                                                                |
+| IPsec   | Internet Protocol Security                                                                                                                                                                                                                 |
+| ISAKMP  | Internet Security Association and Key Management Protocol                                                                                                                                                                                  |
+| ISTP    | Internet Signalling Transport Protocol                                                                                                                                                                                                     |
+
+|         |                                                                                                                                                                                                                                                   |
+|---------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| IVR     | Interactive Voice Response                                                                                                                                                                                                                        |
+| KDC     | Key Distribution Centre                                                                                                                                                                                                                           |
+| MAC     | Message Authentication Code. A fixed-length data item that is sent together with a message to ensure integrity; also known as a MIC.                                                                                                              |
+| MAC     | Media Access Control. It is a sublayer of the Data Link Layer. It normally runs directly over the physical layer.                                                                                                                                 |
+| MD5     | Message Digest 5                                                                                                                                                                                                                                  |
+| MG      | Media Gateway                                                                                                                                                                                                                                     |
+| MGC     | Media Gateway Controller                                                                                                                                                                                                                          |
+| MGCP    | Media Gateway Control Protocol                                                                                                                                                                                                                    |
+| MIB     | Management Information Base                                                                                                                                                                                                                       |
+| MMH     | Multilinear Modular Hash                                                                                                                                                                                                                          |
+| MSB     | Most Significant Bit                                                                                                                                                                                                                              |
+| MTA     | Media Terminal Adapter                                                                                                                                                                                                                            |
+| NCS     | Network Call Signalling                                                                                                                                                                                                                           |
+| NVRAM   | Non-Volatile Random Access Memory                                                                                                                                                                                                                 |
+| OID     | Object Identification                                                                                                                                                                                                                             |
+| OSS     | Operations Support Systems. The back-office software used for configuration, performance, fault, accounting, and security management.                                                                                                             |
+| PKCS    | Public Key Cryptography Standards                                                                                                                                                                                                                 |
+| PKI     | Public Key Infrastructure. A process for issuing public key certificates, which includes standards, Certification Authorities, communication between authorities and protocols for managing certification processes.                              |
+| PKCROSS | Utilizes PKINIT for establishing the inter-realm keys and associated inter-realm policies to be applied in issuing cross-realm service tickets between realms and domains in support of Intradomain and Interdomain CMS-to-CMS signalling (CMSS). |
+| PSTN    | Public Switched Telephone Network                                                                                                                                                                                                                 |
+| QoS     | Quality of Service                                                                                                                                                                                                                                |
+| RADIUS  | Remote Authentication Dial-In User Service                                                                                                                                                                                                        |
+| RC4     | A variable key length stream cipher offered in the ciphersuite, used to encrypt the media traffic in IPCablecom.                                                                                                                                  |
+| RFI     | Radio Frequency Interface                                                                                                                                                                                                                         |
+| RKS     | Record Keeping Server. The device which collects and correlates the various Event Messages.                                                                                                                                                       |
+| RSIP    | Realm Specific IP                                                                                                                                                                                                                                 |
+| RSVP    | Resource Reservation Protocol                                                                                                                                                                                                                     |
+| RTCP    | Real-Time Control Protocol                                                                                                                                                                                                                        |
+| RTO     | Retransmission Timeout                                                                                                                                                                                                                            |
+| RTP     | Real-Time Protocol                                                                                                                                                                                                                                |
+
+|      |                                                                                                                                                                                                                                                               |
+|------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| SA   | Security Association                                                                                                                                                                                                                                          |
+| SDP  | Session Description Protocol                                                                                                                                                                                                                                  |
+| SG   | Signalling Gateway. A SG is a signalling agent that receives/sends SCN native signalling at the edge of the IP network. In particular, the SS7 SG function translates variants ISUP and TCAP in an SS7-Internet Gateway to a common version of ISUP and TCAP. |
+| SIP  | Session Initiation Protocol. An application-layer control (signalling) protocol for creating, modifying, and terminating sessions with one or more participants.                                                                                              |
+| SIP+ | Session Initiation Protocol Plus. An extension to SIP.                                                                                                                                                                                                        |
+| SNMP | Simple Network Management Protocol                                                                                                                                                                                                                            |
+| SRV  | Server                                                                                                                                                                                                                                                        |
+| SS7  | Signalling System No. 7. An architecture and set of protocols for performing out-of-band call signalling with a telephone network.                                                                                                                            |
+| SSL  | Secure Sockets Layer                                                                                                                                                                                                                                          |
+| TCAP | Transaction Capabilities Application Protocol. A protocol within the SS7 stack that is used for performing remote database transactions with a Signalling Control Point.                                                                                      |
+| TD   | Timeout for Disconnect                                                                                                                                                                                                                                        |
+| TFTP | Trivial File Transfer Protocol                                                                                                                                                                                                                                |
+| TGS  | Ticket Granting Server. A sub-system of the KDC used to grant Kerberos tickets.                                                                                                                                                                               |
+| TLS  | Transport Layer Security                                                                                                                                                                                                                                      |
+| UDP  | User Datagram Protocol                                                                                                                                                                                                                                        |
+| UNI  | User-Network Interface                                                                                                                                                                                                                                        |
+| VCI  | Virtual Channel Identifier                                                                                                                                                                                                                                    |
+| VPI  | Virtual Path Identifier                                                                                                                                                                                                                                       |
+
+## 4.2 Conventions
+
+If this Recommendation is implemented, the keywords "MUST" and "SHALL" as well as "REQUIRED" are to be interpreted as indicating a mandatory aspect of this Recommendation.
+
+The keywords indicating a certain level of significance of a particular requirements that are used throughout this Recommendation are summarized below:
+
+"MUST" This word or the adjective "REQUIRED" means that the item is an absolute requirement of this Recommendation.
+
+"MUST NOT" This phrase means that the item is an absolute prohibition of this Recommendation.
+
+"SHOULD" This word or the adjective "RECOMMENDED" means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighed before choosing a different course.
+
+"SHOULD NOT" This phrase means that there may exist valid reasons in particular circumstances when the listed behaviour is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behaviour described with this label.
+
+"MAY"
+
+This word or the adjective "OPTIONAL" means that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product, for example; another vendor may omit the same item.
+
+# 5 Architectural overview of IPCablecom security
+
+## 5.1 IPCablecom reference architecture
+
+Security requirements have been defined for every signalling and media link within the IPCablecom network. In order to understand the security requirements and specifications for IPCablecom, one must first understand the overall architecture. This clause presents a brief overview of the IPCablecom architecture. For a more detailed specification, refer to the IPCablecom architecture Recommendation (ITU-T Rec. J.160).
+
+### 5.1.1 HFC network
+
+In Figure 1, the access network between the MTAs and the CMTS is an HFC network, which employs J.112/J.122 physical layer and MAC layer protocols. J.125 enhanced security (see 6.8) and QoS protocols are enabled over this link.
+
+![Figure 1 – IPCablecom single zone architecture diagram](bffdddb47fced140f8d17fdc2a29f592_img.jpg)
+
+The diagram illustrates the IPCablecom single zone architecture. At the center is a 'Managed IP backbone' represented by a large cloud. To the left, two 'Embedded MTA' units, each containing an 'MTA' and a 'Cable Modem', are connected to an 'HFC access network (J.112)', which in turn connects to an 'AN' (Access Network) node. Both 'AN' nodes are connected to the central 'Managed IP backbone'. Above the backbone is a 'Call Management Server'. To the right of the backbone, a stack of three 'Media Servers' is connected, with labels for 'Announcement servers', 'Conference mixing bridges', and 'J.170\_F01'. Below the media servers, a dashed box contains three stacked components: 'Media Gateway', 'Media Gateway Controller', and 'Signalling Gateway'. This entire stack is connected to the 'Managed IP backbone' and also to a 'PSTN' cloud on the far right. Below the dashed box is an 'OSS Back-office' unit, which is also connected to the 'Managed IP backbone' and has labels for 'Billing', 'Provisioning', 'Problem resolution', 'DHCP servers', and 'TFTP servers'.
+
+Figure 1 – IPCablecom single zone architecture diagram
+
+Figure 1 – IPCablecom single zone architecture
+
+### 5.1.2 Call Management Server
+
+In the context of voice communications applications, a central component of the system is the Call Management Server (CMS). It is involved in both call signalling and the establishment of Dynamic Quality of Service (DQoS). The CMS also performs queries at the PSTN Gateway for LNP (Local Number Portability) and other services necessary for voice communications, including interfacing with the PSTN.
+
+As described in the IPCablecom Architecture Framework, the CMS is divided into the following functional components:
+
+- Call Agent (CA) – The Call Agent maintains network intelligence and call state and controls the media gateway. Most of the time Call Agent is synonymous for Call Management Server.
+- Gate Controller (GC) – The Gate Controller is a logical QoS management component that is typically part of the CMS. The GC coordinates all quality of service authorization and control on behalf of the application service – e.g., voice communications.
+- Media Player Controller (MPC) – The MPC initiates and manages all announcement services provided by the Media Player. The MPC accepts requests from the CMS and arranges for the MP to provide the announcement in the appropriate stream so that the user hears the announcement.
+- Media Gateway Controller (MGC) – The Media Gateway Controller maintains the gateway's portion of call state for communications traversing the Gateway.
+
+A particular CMS can contain any subset of the above listed functional components.
+
+### 5.1.3 Functional categories
+
+The IPCablecom Architecture Framework identifies the following functional categories within the architecture:
+
+- MTA device provisioning;
+- quality of Service (HFC access network and managed IP Backbone);
+- billing interface security;
+- security (specified herein);
+- network call signalling (NCS);
+- PSTN interconnectivity;
+- CODEC functionality and media stream mapping;
+- Audio Server services;
+- electronic surveillance (DF interfaces).
+
+In most cases, each functional category corresponds to a particular IPCablecom Recommendation.
+
+#### 5.1.3.1 Device and service provisioning
+
+During MTA provisioning, the MTA gets its configuration with the help of the DHCP and TFTP servers, as well as the OSS.
+
+Provisioning interfaces need to be secured and have to configure the MTA with the appropriate security parameters (e.g., customer X.509 certificate signed by the Service Provider). This Recommendation specifies the steps in MTA provisioning, but provides detailed specifications only for the security parameters. Refer to ITU-T Rec. J.167 for a full specification on MTA provisioning and customer enrolment.
+
+#### 5.1.3.2 Dynamic Quality of Service
+
+IPCablecom provides guaranteed Quality of Service (QoS) for each voice communication within a single zone with Dynamic QoS (ITU-T Rec. J.163).
+
+DQoS is controlled by the Gate Controller function within the CMS and can guarantee Quality of Service within a single administrative domain. The Gate Controller utilizes the Common Open Policy Service (COPS) protocol to download QoS policy into the CMTS. After that, the QoS reservation is established via J.112/J.122 QoS messaging between the MTA and the CMTS on both sides of the connection.
+
+#### 5.1.3.3 Billing system interfaces
+
+The CMS, CMTS and the PSTN Gateway are all required to send out billing event messages to the Record Keeping Server (RKS). This interface is specified to be RADIUS. Billing information should be checked for integrity and authenticity as well as kept private. This Recommendation defines security requirements and specifications for the communication with RKS.
+
+#### 5.1.3.4 Call signalling
+
+The call signalling architecture defined within IPCablecom is network-based call signalling (NCS) per ITU-T Rec. J.162. The CMS is used to control call set-up, termination and most other call signalling functions. In the NCS architecture, the Call Agent function within the CMS is used in call signalling and utilizes the MGCP protocol.
+
+#### 5.1.3.5 PSTN interconnectivity
+
+The PSTN interface to the voice communications capabilities of the IPCablecom network is through the Signalling and Media Gateways (SG and MG). Both of these gateways are controlled with the MGC (Media Gateway Controller). The MGC may be standalone or combined with a CMS. For further detail on PSTN Gateways, refer to ITU-T Rec. J.171.x-series.
+
+All communications between the MGC and the SG and MG may be over the same-shared IP network and is subject to similar threats (e.g., privacy, masquerade, denial-of-service) that are encountered in other links in the same network. This Recommendation defines the security requirements and specifications for the PSTN Gateway links.
+
+When communications from an MTA to a PSTN phone are made, bearer channel traffic is passed directly between an MTA and an MG. The protocols used in this case are RTP and RTCP, as in the MTA-to-MTA case. Both security requirements and specifications are very similar to the MTA-to-MTA bearer requirements and are fully defined in this Recommendation. After a voice communication enters the PSTN, the security requirements as well as specifications are the responsibility of the PSTN.
+
+#### 5.1.3.6 CODEC functionality and media stream mapping
+
+The media stream between two MTAs or between an MTA and a PSTN Gateway utilizes the RTP protocol. Although ITU-T J.125 provides for privacy over the HFC network, the potential threats within the rest of the voice communications network require that the RTP packets be encrypted end-to-end<sup>1</sup>.
+
+In addition to RTP, there is an accompanying RTCP protocol, primarily used for reporting of RTCP statistics. In addition, RTCP packets may carry CNAME – a unique identifier of the sender of RTP packets. RTCP also defines a BYE message<sup>2</sup> that can be used to terminate an RTP session. These two additional RTCP functions raise privacy and denial-of-service threats. Due to these threats, RTCP security requirements are the same as the requirements for all other end-to-end (SIP+) signalling and are addressed in the same manner.
+
+---
+
+<sup>1</sup> In general, it is possible for an MTA-to-MTA or MTA-to-PSTN connection to cross the networks of several different Service Providers. In the process, this path may cross a PSTN network. This is an exception to the rule, where all RTP packets are encrypted end-to-end. The media traffic inside a PSTN network does not utilize RTP and has its own security requirements. Thus, in this case the encryption would not be end-to-end and would terminate at the PSTN Gateway on both sides of the intermediate PSTN network.
+
+<sup>2</sup> The RTCP BYE message should not be confused with the SIP+ BYE message that is also used to indicate the end of a voice communication within the network.
+
+In addition to MTAs and PSTN Gateways, Media Servers may also participate in the media stream flows. Media Servers are network-based components that operate on media flows to support various voice communications service options. Media Servers perform audio bridging, play terminating announcements, provide interactive voice response services, and so on. Both media stream and signalling interfaces to a Media Server are the same as the interfaces to an MTA. For more information on Codec functionality, see ITU-T Rec. J.161.
+
+#### **5.1.3.7 Audio Server services**
+
+Audio Server interfaces provide a suite of signalling protocols for providing announcement and audio services in an IPCablecom network.
+
+##### **5.1.3.7.1 Media Player Controller (MPC)**
+
+The Media Player Controller (MPC) initiates and manages all announcement services provided by the Media Player. The MPC accepts requests from the CMS and arranges for the MP to provide the announcement in the appropriate stream so that the user hears the announcement. The MPC also serves as the termination for certain calls routed to it for IVR services. When the MP collects information from the end-user, the MPC is responsible for interpreting this information and managing the IVR session accordingly. The MPC manages call state.
+
+##### **5.1.3.7.2 Media Player (MP)**
+
+The Media Player (MP) is a media resource server. It is responsible for receiving and interpreting commands from the MPC and for delivering the appropriate announcement(s) to the MTA. The MP provides the media stream with the announcement contents. The MP also is responsible for accepting and reporting user inputs (e.g., DTMF tones). The MP functions under the control of the MPC.
+
+#### **5.1.3.8 Electronic surveillance**
+
+The event interface between the CMS and the DF provides descriptions of calls, necessary to perform wiretapping. This information includes the media stream encryption key and the corresponding encryption algorithm. This event interface uses RADIUS and is similar to the CMS-RKS interface.
+
+The COPS interface between the CMS and the CMTS is used to signal the CMTS to start/stop duplicating media packets to the DF for a particular call. This is the same COPS interface that is used for (DQoS) Gate Authorization messages.
+
+## 5.2 Threats
+
+Figure 2 contains the interfaces that were analysed for security.
+
+![Figure 2 – IPCablecom secured interfaces. A network diagram showing various nodes and their interfaces. Nodes include TFTP server, OSS / Prov server, MSO KDC, Telephony KDC, EBP, MPC, MTA, CMS, MP, RKS, CMTS, DF, Remote MTA, CM, MG, and MGC. Interfaces are labeled with packet types such as TFTP, SNMP, PKINIT, NCS, RADIUS*, RTP, RTCP, DOCSIS 1.1, TGCP, and CMSS.](2b3a967f6ce4f23649be995a353e39f8_img.jpg)
+
+```
+
+graph TD
+    TFTP_server((TFTP server)) -- "pkt-s1: TFTP" --> OSS_Prov_server((OSS / Prov server))
+    OSS_Prov_server -- "pkt-s26: MTA FQDN" --> MSO_KDC((MSO KDC))
+    OSS_Prov_server -- "pkt-s0: SNMP" --> MTA((MTA))
+    OSS_Prov_server -- "pkt-s12: PKINIT" --> Telephony_KDC((Telephony KDC))
+    OSS_Prov_server -- "pkt-s13: PKINIT" --> CMS((CMS))
+    Telephony_KDC -- "pkt-s27: HTTP" --> CMS
+    EBP1((EBP)) -- "pkt-s16: CMSS" --> EBP2((EBP))
+    EBP2 -- "pkt-s16: CMSS" --> CMS2((CMS))
+    CMS2 -- "pkt-s16: CMSS" --> DF2((DF))
+    DF2 -- "pkt-s24: RADIUS*" --> DF1((DF))
+    DF1 -- "pkt-s23: RADIUS*" --> MGC((MGC))
+    MGC -- "pkt-s10: TGCP" --> MG((MG))
+    MG -- "pkt-s32: DOCSIS 1.1" --> CM((CM))
+    CM -- "pkt-s25: RADIUS*" --> CMTS((CMTS))
+    CMTS -- "pkt-s22: RADIUS*" --> DF
+    DF -- "pkt-s21: RADIUS*" --> CMS
+    CMS -- "pkt-s16: CMSS" --> CMS2
+    CMS -- "pkt-s6: RADIUS*" --> RKS((RKS))
+    RKS -- "pkt-s7: RADIUS*" --> CMTS
+    RKS -- "pkt-s8: CORP" --> CMS
+    MTA -- "pkt-s5: NCS" --> CMS
+    MTA -- "pkt-s1: TFTP" --> TFTP_server
+    MTA -- "pkt-s20: ASP" --> MPC((MPC))
+    MTA -- "pkt-s3: RTP" --> Remote_MTA((Remote MTA))
+    MTA -- "pkt-s4: RTCP" --> Remote_MTA
+    MTA -- "pkt-s3: RTP" --> MP((MP))
+    MTA -- "pkt-s4: RTCP" --> MP
+    MTA -- "pkt-s25: RADIUS*" --> CMTS
+  
+```
+
+Figure 2 – IPCablecom secured interfaces. A network diagram showing various nodes and their interfaces. Nodes include TFTP server, OSS / Prov server, MSO KDC, Telephony KDC, EBP, MPC, MTA, CMS, MP, RKS, CMTS, DF, Remote MTA, CM, MG, and MGC. Interfaces are labeled with packet types such as TFTP, SNMP, PKINIT, NCS, RADIUS\*, RTP, RTCP, DOCSIS 1.1, TGCP, and CMSS.
+
+Figure 2 – IPCablecom secured interfaces
+
+There are additional interfaces identified in IPCablecom but for which protocols are not specified. In those cases, the corresponding security protocols are also not specified, and those interfaces are not listed in Figure 2.
+
+As well, the interfaces for which security is not required in IPCablecom are not listed.
+
+The following clause summarizes general threats and the corresponding attacks that are relevant in the context of IP voice communications. This list of threats is not based on the knowledge of the specific protocols or security mechanisms employed in the network. A more specific summary of threats that are based on the functionality of each network element is listed in 5.2.6.
+
+Some of the outlined threats cannot be addressed purely by cryptographic means – physical security and/or fraud management should also be used. These threats may be important, but cannot be fully addressed within the scope of IPCablecom. How vendors and cable operators implement fraud management and physical security will differ and in this case a standard is not required for interoperability.
+
+### **5.2.1 Theft of network services**
+
+In the context of voice communications, the main services that may be stolen are:
+
+- long-distance service;
+- local (subscription) voice communications service;
+- video conferencing;
+- network-based three-way calling;
+- Quality of Service.
+
+#### **5.2.1.1 MTA clones**
+
+One or more MTAs can masquerade as another MTA by duplicating its permanent identity and keys. The secret cryptographic keys may be obtained by either breaking the physical security of the MTA or by employing cryptanalysis.
+
+When an MTA is broken into, the perpetrator can steal voice communications service and charge it all to the original owner. The feasibility of such an attack depends on where an MTA is located. This attack must be seriously considered in the cases when an MTA is located in an office or apartment building, or on a street corner.
+
+An owner might break into his or her own MTA in at least one instance – after a false account with the cable operator providing the voice communications service had been set up. The customer name, address, and Social Security number may all be invalid or belong to someone else. The provided credit card number may be stolen. In that case, the owner of the MTA would not mind giving out the MTA cryptographic identity to others – he or she would not have to pay for service anyway.
+
+In addition to cloning of the permanent cryptographic keys, temporary (usually symmetric) keys may also be cloned. Such an attack is more complex, since the temporary keys expire more often and have to be frequently redistributed. The only reason why someone would attempt this attack is if the permanent cryptographic keys are protected much better than the temporary ones, or if the temporary keys are particularly easy to steal or discover with cryptanalysis.
+
+#### **5.2.1.2 Other clones**
+
+It is conceivable that the cryptographic identity of another network element, such as a CMTS or a CMS, may be cloned. Such an attack is most likely to be mounted by an insider such as a corrupt or disgruntled employee.
+
+#### **5.2.1.3 Subscription fraud**
+
+A customer sets up an account under false information.
+
+#### **5.2.1.4 Non-payment for voice communications services**
+
+A customer stops paying his or her bill, but continues to use the MTA for voice communications service. This can happen if the network does not have an automated method to revoke the customer's access to the network.
+
+#### **5.2.1.5 Protocol attacks against an MTA**
+
+A weakness in the protocol can be manipulated to allow an MTA to authenticate to a network server with a false identity or hijack an existing voice communication. This includes replay and man-in-the-middle attacks.
+
+#### **5.2.1.6 Protocol attacks against other network elements**
+
+A perpetrator might employ similar protocol attacks to masquerade as a different network element, such as a CMTS or a CMS. Such an attack may be used in collaboration with cooperating MTAs to steal service.
+
+#### **5.2.1.7 Theft of services provided by the MTA**
+
+Services such as the support for multiple MTA ports, 3-way calling and call waiting may be implemented entirely in the MTA, without any required interaction with the network.
+
+##### **5.2.1.7.1 Attacks**
+
+MTA code to support these services may be downloaded illegally by an MTA clone, in which case the clone has to interact with the network to get the download. In that case, this threat is no different from the network service theft described in the previous clause.
+
+Alternatively, downloading an illegal code image using some illegal out-of-band means can also enable these services. Such service theft is much harder to prevent (a secure software environment within the MTA may be required). On the other hand, in order for an adversary to go through this trouble, the price for these MTA-based services has to make the theft worthwhile.
+
+An implication of this threat is that valuable services cannot be implemented entirely inside the MTA without a secure software environment in addition to tamper-proof protection for the cryptographic keys. (While a secure software environment within an MTA adds significant complexity, it is an achievable task.)
+
+#### **5.2.1.8 MTA moved to another network**
+
+A leased MTA may be reconfigured and registered with another network, contrary to the intent and property rights of the leasing company.
+
+### **5.2.2 Bearer channel information threats**
+
+This class of threats is concerned with the breaking of privacy of voice communications over the IP bearer channel. Threats against non-VoIP communications are not considered here and assumed to require additional security at the application layer.
+
+#### **5.2.2.1 Attacks**
+
+Clones of MTAs and other network elements, as well as protocol manipulation attacks, also apply in the case of bearer channel information threats. These attacks are already described under the Service Theft threats.
+
+MTA cloning attacks mounted by the actual owner of the MTA are less likely in this case, but not inconceivable. An owner of an MTA may distribute clones to unsuspecting victims, so that he or she can later spy on them.
+
+##### **5.2.2.1.1 Off-line cryptanalysis**
+
+Bearer channel information may be recorded and then analysed over a period of time, until the encryption keys are discovered through cryptanalysis. The discovered information may be of value even after a relatively long time has passed.
+
+### **5.2.3 Signalling channel information threats**
+
+Signalling information, such as the caller identity and the services to which each customer subscribes, may be collected for marketing purposes. The caller identity may also be used illegally to locate a customer that wishes to keep his or her location private.
+
+#### **5.2.3.1 Attacks**
+
+Clones of MTAs and other network elements, as well as protocol manipulation attacks, also apply in the case of the signalling channel information threats. These attacks are already described in the clause on Service Theft threats.
+
+MTA cloning attacks mounted by the actual owner of the MTA is theoretically possible in this case. An owner of an MTA may distribute clones to the unsuspecting victims, so that he or she can monitor their signalling messages (e.g., for information with marketing value). The potential benefits of such an attack seem unjustified, however.
+
+##### **5.2.3.1.1 Caller ID**
+
+A number of a party initiating a voice communication is revealed, even though a number is not generally available (i.e., is "unlisted") and the owner of that number enabled ID blocking.
+
+##### **5.2.3.1.2 Information with marketing value**
+
+Dialled numbers and the type of service customers use may be gathered for marketing purposes by other corporations.
+
+### **5.2.4 Service disruption threats**
+
+This class of threats is aimed at disrupting the normal operation of voice communications. The motives for denial-of-service attacks may be malicious intent against a particular individual or against the service provider; or, perhaps a competitor wishes to degrade the performance of another service provider and use the resulting problems in an advertising campaign.
+
+#### **5.2.4.1 Attacks**
+
+##### **5.2.4.1.1 Remote interference**
+
+A perpetrator is able to manipulate the protocol to close down ongoing voice communications. This might be achieved by masquerading as an MTA involved in such an ongoing communication. The same effect may be achieved if the perpetrator impersonates another network element, such as a gate controller or an edge router during either call set-up or voice packet routing.
+
+Depending on the signalling protocol security, it might be possible for the perpetrator to mount this attack from the MTA, in the privacy of his or her own home.
+
+Clones of MTAs and other network elements, as well as protocol manipulation attacks, also apply in the case of the service disruption threats. These attacks are described under Service Theft threats.
+
+MTA cloning attacks mounted by the actual owner of the MTA can theoretically be used in service disruption against unsuspecting clone owners. However, since there are so many other ways to cause service disruption, such an attack cannot be taken seriously in this context.
+
+### 5.2.5 Repudiation
+
+In a network where masquerading (using the above-mentioned cloning and protocol manipulation techniques) is common or easily achievable, a customer may repudiate a particular communication (and, thus deny responsibility for paying for it) on that basis.
+
+In addition, unless public key-based digital signatures are employed on each message, the source of each message cannot be absolutely proven. If a signature over a message that originated at an MTA is based on a symmetric key that is shared between that MTA and a network server (e.g., the CMS), it is unclear if the owner of the MTA can claim that the service provider somehow falsified the message.
+
+However, even if each message were to carry a public key-based digital signature and if each MTA were to employ stringent physical security, the customer can still claim in court that someone else initiated that communication without his or her knowledge, just as a customer of a telecommunications carrier on the PSTN can claim, e.g., that particular long distance calls made from the customer's telephone were not authorized by the customer. Such telecommunications carriers commonly address this situation by establishing contractual and/or tariffed relationships with customers in which customers assume liability for unauthorized use of the customer's service. These same contractual principles are typically implemented in service contracts between information services providers such as ISPs and their subscribers. For these reasons, the benefits of non-repudiation seem dubious at best and do not appear to justify the performance penalty of carrying a public key-based digital signature on every message.
+
+### 5.2.6 Threat summary
+
+This clause provides a summary of the above threats and attacks and a brief assessment of their relative importance.
+
+#### 5.2.6.1 Primary threats
+
+– **Theft of Service:** Attacks are:
+
+- **Subscription fraud:** This attack is prevalent in today's telephony systems (i.e., the PSTN) and requires little economic investment. It can only be addressed with a Fraud Management system.
+- **Non-payment for services:** Within the PSTN, telecommunications carriers usually do not prosecute the offenders, but simply shut down their accounts. Because prosecution is expensive and not always successful, it is a poor counter to this attack. Methods such as debit-based billing and device authorization (pay as you play), increasingly common in the wireless sector of the PSTN, might be a possible solution for this attack in the IPCablecom context. This threat can also be minimized with effective Fraud Management systems.
+- **MTA clones:** This threat requires more technical knowledge than the previous two threats. A technically-knowledgeable adversary or underground organization might offer cloning services for profit. This threat is most effective when combined with subscription fraud, where an MTA registered under a fraudulent account is cloned. This threat can be addressed with both Fraud Management and physical security inside the MTA, or a combination of both.
+- **Impersonation of a network server:** With proper cryptographic mechanisms, authorization and procedural security in place, this attack is unlikely, but has the potential for great damage.
+- **Protocol manipulation:** Can occur only when security protocols are flawed or when not enough cryptographic strength is in place.
+
+- **Bearer Channel Information Disclosure:** Attacks are:
+  - Simple snooping: This would happen if voice packets were sent in the clear over some segment of the network. Even if that segment appears to be protected, an insider may still compromise it. This is the only major attack on privacy. The bearer channel privacy attacks listed below are possible but are all of secondary importance.
+  - MTA clones: Again, this threat requires more technical knowledge but can be offered as a service by an underground organization. A most likely variation of this attack is when a publicly accessible MTA (e.g., in an office or apartment building) is cloned.
+  - Protocol manipulation: A flawed protocol may somehow be exploited to discover bearer channel encryption keys.
+  - Off-line cryptanalysis: Even when media packets are protected with encryption, they can be stored and analysed for long periods of time, until the decryption key is finally discovered. Such an attack is not likely to be prevalent, since it is justified only for particularly valuable customer-provided information (IPCablecom security is not required to protect data). This attack is more difficult to perform on voice packets (as opposed to data). Still, customers are very sensitive to this threat and it can serve as the basis for a negative publicity campaign by competitors.
+- **Signalling Information Disclosure:** This threat is listed as primary only due to potential for bad publicity and customer sensitivity to keeping their numbers and location private. All of the attacks listed below are similar to those for bearer channel privacy and are not described here:
+  - Simple snooping;
+  - MTA clones;
+  - Protocol manipulation;
+  - Off-line cryptanalysis;
+  - Service disruption.
+
+#### 5.2.6.2 Secondary threats
+
+- **Theft of MTA-based services:** Based on the voice communications services that are planned for the near future, this threat does not appear to have potential for significant economic damage. This could possibly change with the introduction of new value-added services in the future.
+- **Illegally registering a leased MTA with a different Service Provider:** Leased MTAs can normally be tracked. Most likely, this threat is combined with the actual theft of a leased MTA. Thus, this threat does not appear to have potential for widespread damage.
+
+## 5.3 Security architecture
+
+### 5.3.1 Overview of security interfaces
+
+Figure 3 summarizes all of the IPCablecom security interfaces, including key management.
+
+![A complex network diagram showing security interfaces between various components like TFTP server, MPC, MP, Remote MTA, MG, CM, MTA, OSS/Prov server, MSO KDC, Telephony KDC, EBP, CMS, RKS, CMTS, DF, and MGC. Each interface is labeled with a packet type (e.g., pkt-s1, pkt-s2) and security protocols (e.g., TFTP, Hash & Encryption, Kerberos, PKINIT, NCS, RADIUS, COPS, DOCSIS 1.1, TGCP).](26d664119ad25250780f554633444e54_img.jpg)
+
+The diagram illustrates the security architecture and interfaces for IPCablecom. It features a central **MTA** connected to various external and internal components. The interfaces are defined by packet types and associated security protocols:
+
+- MTA to TFTP server:** pkt-s1: TFTP (Hash & Encryption)
+- MTA to OSS/Prov server:** pkt-s26: MTA FQDN (Kerberos), pkt-s12: PKINIT (Issue Kerberos tickets)
+- MTA to MSO KDC:** pkt-s13: PKINIT (Issue Kerberos tickets)
+- MTA to Telephony KDC:** pkt-s27: HTTP (IPsec/IKE/Kerb)
+- MTA to EBP (top right):** pkt-s16: CMSS (TLS)
+- MTA to CMS (middle right):** pkt-s16: CMSS (TLS)
+- MTA to RKS:** pkt-s5: NCS (IPsec/Kerberos + PKINIT), pkt-s6: RADIUS\* (IPsec/IKE/Kerb)
+- MTA to CMTS:** pkt-s25: RADIUS\* (IPsec/IKE/Kerb), pkt-s7: RADIUS\*\* (IPsec/IKE/Kerb), pkt-s8: COPS (IPsec/IKE/Kerb)
+- MTA to DF (bottom right):** pkt-s21: RADIUS\* (IPsec/IKE/Kerb)
+- MTA to MGC:** pkt-s10: TGCP (IPsec/IKE/Kerb)
+- MTA to CM:** pkt-s2: DOCSIS 1.1 (BPI+ BPIKM)
+- MTA to MG:** pkt-s3: RTP (Cipher + HMAC/CMS-based KM), pkt-s4: RTCP (Cipher + HMAC/CMS-based KM), pkt-s3: RTP (Cipher + HMAC/CMS-based KM), pkt-s4: RTCP (Cipher + HMAC/CMS-based KM)
+- MTA to Remote MTA:** pkt-s3: RTP (Cipher + HMAC/CMS-based KM), pkt-s4: RTCP (Cipher + HMAC/CMS-based KM)
+- MTA to MP:** pkt-s20: ASP
+- MTA to MPC:** pkt-s1: TFTP (Hash & Encryption), pkt-s9: SNMP (SNMPv3 Security)
+- CMS to EBP (bottom right):** pkt-s16: CMSS (TLS)
+- CMS to CMS (bottom right):** pkt-s16: CMSS (TLS)
+- CMS to DF:** pkt-s24: RADIUS\* (IPsec/IKE+)
+- DF to DF (bottom right):** pkt-s23: RADIUS\* (IPsec/IKE/Kerb)
+
+J.170\_F03
+
+A complex network diagram showing security interfaces between various components like TFTP server, MPC, MP, Remote MTA, MG, CM, MTA, OSS/Prov server, MSO KDC, Telephony KDC, EBP, CMS, RKS, CMTS, DF, and MGC. Each interface is labeled with a packet type (e.g., pkt-s1, pkt-s2) and security protocols (e.g., TFTP, Hash & Encryption, Kerberos, PKINIT, NCS, RADIUS, COPS, DOCSIS 1.1, TGCP).
+
+Figure 3 – IPCablecom security interfaces with key management
+
+In Figure 3, each interface label is of the form:
+
+**<label>: <protocol> { <security protocol>/<key management protocol> }**
+
+If the key management protocol is missing, it is not needed for that interface. IPCablecom interfaces that do not require security are not shown in Figure 3.
+
+Table 1 briefly describes each of the interfaces shown in Figure 3.
+
+**Table 1 – IPCablecom security interfaces table**
+
+| Interface | Components        | Description                                                                                                                                                                                                                                                                                                                                                         |
+|-----------|-------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| pkt-s0    | MTA-PS/OSS        | Immediately after the DHCP sequence in the Secure Provisioning Flow, the MTA performs Kerberos-based key management with the Provisioning Server to establish SNMPv3 keys. The MTA bypasses Kerberized SNMPv3 and uses SNMPv2c in the Basic and Hybrid Flows.                                                                                                       |
+| pkt-s1    | MTA-TFTP          | MTA Configuration file download. When the Provisioning Server in the Secure Provisioning Flow sends an SNMP Set command to the MTA, it includes both the configuration name and the hash of the file. Later, when the MTA downloads the file, it authenticates the configuration file using the hash value. The configuration file may be optionally encrypted.     |
+| pkt-s2    | CM-CMTS           | J.112: This interface should be secured with BPI+ using BPI key management. BPI+ privacy layer on the HFC link.                                                                                                                                                                                                                                                     |
+| pkt-s3    | MTA-MTA<br>MTA-MG | RTP: End-to-end media packets between two MTAs, or between MTA and MG. RTP packets are encrypted directly with the chosen cipher. Message integrity is optionally provided by an HMAC (Hashed Message Authentication Code). Keys are randomly generated, and exchanged by the two endpoints inside the signalling messages via the CMS or other application server. |
+| pkt-s4    | MTA-MTA<br>MTA-MG | RTCP: RTCP control protocol for RTP. Message integrity and encrypted by selected cipher. The RTCP keys are derived using the same secret negotiated during the RTP key management. No additional key management messages are needed or utilized.                                                                                                                    |
+| pkt-s5    | MTA-CMS           | NCS: Message integrity and privacy via IPsec. Key management is with Kerberos with PKINIT (public key initial authentication) extension.                                                                                                                                                                                                                            |
+| pkt-s6    | RKS-CMS           | RADIUS: IPsec is used for both message integrity, as well as privacy. Key management is IKE or Kerberos.                                                                                                                                                                                                                                                            |
+| pkt-s7    | RKS-CMTS          | RADIUS: IPsec is used for both message integrity, as well as privacy. Key management is IKE or Kerberos.                                                                                                                                                                                                                                                            |
+| pkt-s8    | CMS-CMTS          | COPS: COPS protocol between the GC and the CMTS, used to download QoS authorization to the CMTS. Security is provided with IPsec for message integrity, as well as privacy. Key management is IKE or Kerberos.                                                                                                                                                      |
+| pkt-s9    |                   | This interface has been removed from the IPCablecom architecture.                                                                                                                                                                                                                                                                                                   |
+| pkt-s10   | MGC-MG            | TGCP: IPCablecom interface to the PSTN Media Gateway. IPsec is used for both message integrity and privacy. Key management is IKE or Kerberos.                                                                                                                                                                                                                      |
+| pkt-s11   |                   | This interface has been removed from the IPCablecom architecture.                                                                                                                                                                                                                                                                                                   |
+
+**Table 1 – IPCablecom security interfaces table**
+
+| Interface | Components                                                        | Description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
+|-----------|-------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| pkt-s12   | MTA-MSO<br>KDC                                                    | PKINIT: An AS-REQ message is sent to the KDC with public-key cryptography used for authentication. The KDC verifies the certificate and issues either a service ticket or a ticket granting ticket (TGT), depending on the contents of the AS Request. The AS Reply returned by the KDC contains a certificate chain and a digital signature that are used by the MTA to authenticate this message. In the case that the KDC returns a TGT, the MTA then sends a TGS Request to the KDC to which the KDC replies with a TGS Reply containing a service ticket. The TGS Request/Reply messages are authenticated using a symmetric session key inside the TGT. |
+| pkt-s13   | MTA-telephony<br>KDC                                              | PKINIT: See pkt-s12 above.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+| pkt-s14   |                                                                   | This interface has been removed from the IPCablecom architecture.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
+| pkt-s15   |                                                                   | This interface has been removed from the IPCablecom architecture.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
+| pkt-s16   | CMS-CMS<br>CMS-MGC<br>CMS-EBP<br>EBP-EBP                          | SIP: TLS is used for both message integrity and privacy. Certificates are used for mutual authentication during the TLS handshake.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
+| pkt-s17   |                                                                   | This interface has been removed from the IPCablecom architecture.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
+| pkt-s18   |                                                                   | This interface has been removed from the IPCablecom architecture.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
+| pkt-s19   |                                                                   | This interface has been removed from the IPCablecom architecture.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
+| pkt-s20   | MPC-MP                                                            | ASP: IPsec is used for both message integrity and privacy. Key management is IKE or Kerberos.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
+| pkt-s21   | DF-CMS                                                            | RADIUS: IPsec is used for both message integrity and privacy. Key management is IKE or Kerberos.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
+| pkt-s22   | DF-CMTS                                                           | RADIUS: IPsec is used for both message integrity and privacy. Key management is IKE or Kerberos.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
+| pkt-s23   | DF-MGC                                                            | RADIUS: IPsec is used for both message integrity and privacy. Key management is IKE or Kerberos.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
+| pkt-s24   | DF-DF                                                             | RADIUS: IPsec is used for both message integrity and privacy. Key management is IKE+.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+| pkt-s25   | RKS-MGC                                                           | RADIUS: IPsec is used for both message integrity, as well as privacy. Key management is IKE or Kerberos.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
+| pkt-s26   | OSS/Prov Serv<br>– MSO KDC<br>OSS/Prov Serv<br>– Telephony<br>KDC | The KDC uses Kerberos to map the MTA's MAC address to its FQDN for the purpose of authenticating the MTA before issuing it a ticket.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
+| pkt-s27   | CMS-PS/OSS                                                        | HTTP: IPsec is used for both message integrity and privacy. Key management is IKE or Kerberos.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
+
+### **5.3.2 Security assumptions**
+
+#### **5.3.2.1 CMTS downstream messages are trusted**
+
+As mentioned previously, it is assumed that CMTS downstream messages cannot be easily modified in transit and a CMTS can be impersonated only at great expense.
+
+Most messages secured in this Recommendation either move over the shared IP network in addition to the J.112 path, or do not go over J.112 at all.
+
+In one case – the case of J.112 QoS messages exchanged between the CMTS and the CM – this assumption does not apply. Although J.112 QoS messages (both upstream and downstream) include an integrity check, the corresponding (BPI+) key management does not authenticate the identity of the CMTS. The CM is unable to cryptographically know that the network element it has connected to is the true CMTS for that network. However, even if a CMTS could be impersonated, it would allow only limited denial-of-service attacks. This vulnerability is not considered to be worth the effort and the expense of impersonating a CMTS.
+
+#### **5.3.2.2 Non-repudiation not supported**
+
+Non-repudiation, in this Recommendation, means that an originator of a message cannot deny that he or she sent that message. In this voice communications architecture, non-repudiation is not supported for most messages, with the exception of the top key management layer. This decision was based on the performance penalty incurred with each public key operation. The most important use for non-repudiation would have been during communications set up – to prove that a particular party had initiated that particular communication. However, due to very strict requirements on the set-up time, it is not possible to perform public key operations for each communication.
+
+#### **5.3.2.3 Root Private Key compromise protection**
+
+The cryptographic mechanisms defined in this Recommendation are based on a Public Key Infrastructure (PKI). As is the case with most other architectures that are based on a PKI, there is no automated recovery path from a compromise of a Root Private Key. However, with proper safeguards, the probability of this happening is very low, to the point that the risk of a Root Private Key compromise occurring is outweighed by the benefits of this architecture.
+
+The corresponding Root Public Key is stored as a read-only parameter in many components of this architecture. Once the Root Private Key has been compromised, each manufacturer's certificate would have to be manually reconfigured.
+
+Due to this limitation of a PKI, the Root Private Key must be very carefully guarded with procedural and physical security. And, it must be sufficiently long so that its value cannot be discovered with cryptographic attacks within the expected lifetime of the system.
+
+#### **5.3.2.4 Limited prevention of denial-of-service attacks**
+
+This Recommendation does not attempt to address all or even most denial-of-service attacks. The cryptographic mechanisms defined in this Recommendation prevent some denial-of-service attacks that are particularly easy to mount and are hard to detect. For example, they will prevent a compromised MTA from masquerading as other MTAs in the same upstream HFC segment and interrupting ongoing communications with illicit HANGUP messages.
+
+This Recommendation will also prevent more serious denial-of-service attacks, such as an MTA masquerading as a CMS in a different network domain that causes all communications set-up requests to fail.
+
+On the other hand, denial-of-service attacks where a router is taken out of service or is bombarded with bad IP packets are not addressed. In general, denial-of-service attacks that are based on damaging one of the network components can only be solved with procedural and physical security, which is out of the scope of this Recommendation.
+
+Denial-of-service attacks where network traffic is overburdened with bad packets cannot be prevented in a large network (although procedural and physical security helps), but can usually be detected. Detection of such an attack and of its cause is out of scope of this Recommendation.
+
+For example, denial-of-service attacks where a router is taken out of order or is bombarded with bogus IP packets cannot be prevented.
+
+### **5.3.3 Susceptibility of network elements to attack**
+
+This clause describes the amount and the type of trust that can be assumed for each element of the voice communications network. It also describes the specific threats that are possible if each network component is compromised. These threats are based on the functionality specified for each component. The general categories of threats are described in 5.2.
+
+Both the trust and the specific threats are described with the assumption that no cryptographic or physical security has been employed in the system, with the exception of the security per ITU-T Rec. J.125 that is on the HFC J.112 links. The goal of this security Recommendation is to address threats that are relevant to this voice communications system.
+
+#### **5.3.3.1 Managed IP network**
+
+It is assumed that the same IP network may be shared between multiple, possibly competing service providers. It is also assumed that the service provider may provide multiple services on the same IP network, e.g., Internet connectivity. No assumptions can be made about the physical security of each link in this IP network. An intruder can pop up at any location with the ability to monitor traffic, perform message modification and to reroute messages.
+
+#### **5.3.3.2 MTA**
+
+The MTA is considered to be an untrusted network element. It is operating inside customer premises, considered to be a hostile environment. It is assumed that a hostile adversary has the ability to open up the MTA and make software and even hardware modifications to fit his or her needs. This would be done in the privacy of the customer's home.
+
+The MTA communicates with the CMTS over the shared J.112 path and has access to downstream and upstream messages from other MTAs within the same HFC segment.
+
+An MTA is responsible for:
+
+- initiating and receiving communications to/from another MTA or the PSTN;
+- negotiating QoS.
+
+A compromise of an MTA can result in:
+
+- MTA clones that are capable of:
+  - accessing basic service and any enhanced features in the name of another user's account;
+  - violating privacy of the owner of the compromised MTA that does not know that the keys were stolen;
+  - identity fraud;
+- an MTA running a bad code image that disrupts communications made by other MTAs or degrades network performance.
+
+#### 5.3.3.3 CMTS
+
+The CMTS communicates both over the J.112 path and over the shared IP network. When the CMTS sends downstream messages over the J.112 path, it is assumed that a perpetrator cannot modify them or impersonate the CMTS. Implementing ITU-T Rec. J.125 over that path provides for privacy.
+
+However, when the CMTS is communicating over the shared IP network (e.g., with the CMS or another CMTS), no such assumptions can be made.
+
+While the CMTS, as well as voice communications network servers, are more trusted than the MTAs, they cannot be trusted completely. There is always a possibility of an insider attack.
+
+Insider attacks at the CMTS should be addressed by cryptographic authentication and authorization of the CMTS operators, as well as by physical and procedural security, which are all out of the scope of the IPCablecom Recommendations.
+
+A CMTS is responsible for:
+
+- reporting billing-related statistics to the RKS;
+- QoS allocation for MTAs over the J.112 path;
+- implementation of BPI+ (MAC layer security) and corresponding key management.
+
+A compromise of a CMTS may result in:
+
+- service theft by reporting invalid information to the RKS;
+- unauthorized levels of QoS;
+- loss of privacy, since the CMTS holds J.112 keys. This may not happen if additional encryption is provided above the MAC layer;
+- degraded performance of some or all MTAs in that HFC segment;
+- some or all of the MTAs in one HFC segment completely taken out of service.
+
+#### 5.3.3.4 Voice communications network servers are untrusted network elements
+
+Application servers used for voice communications (e.g., CMS, RKS, Provisioning, OSS, DHCP and TFTP servers) reside on the network and can potentially be impersonated or subjected to insider attacks. The main difference would be in the damage that can be incurred in the case a particular server is impersonated or compromised.
+
+Threats that are associated with each network element are discussed in the following subclauses. To summarize those threats, a compromise or impersonation of each of these servers can result in a wide-scale service theft, loss of privacy, and in highly damaging denial-of-service attacks.
+
+In addition to authentication of all messages to and from these servers (specified in this Recommendation), care should be taken to minimize the likelihood of insider attacks. They should be addressed by cryptographic authentication and authorization of the operators, as well as by stringent physical and procedural security, which are all out of scope of the IPCablecom Recommendations.
+
+##### 5.3.3.4.1 CMS
+
+The Call Management Server is responsible for:
+
+- authorizing individual voice communications by subscribers;
+- QoS allocation;
+- initializing the billing information in the CMTS;
+
+- distributing per communication keys for MTA-MTA signalling, bearer channel, and DQoS messages on the MTA-CMTS and CMTS-CMTS links;
+- interface to PTSN gateway.
+
+A compromised CMS can result in:
+
+- free voice communications service to all of the MTAs that are located in the same network domain (up to 100 000). This may be accomplished by:
+  - allowing unauthorized MTAs to create communications;
+  - uploading invalid or wrong billing information to the CMTS;
+  - combination of both of the above;
+- loss of privacy, since the CMS distributes bearer channel keys;
+- unauthorized allocation of QoS;
+- unauthorized disclosure of customer identity, location (e.g., IP address), communication patterns, and a list of services to which the customer subscribes.
+
+##### 5.3.3.4.2 RKS
+
+The RKS is responsible for collecting billing events and reporting them to the billing system. A compromised RKS may result in:
+
+- free or reduced-rate service due to improper reporting of statistics;
+- billing to a wrong account;
+- billing customers for communications that were never made, i.e., fabricating communications;
+- unauthorized disclosure of customer identity, personal information, service usage patterns, and a list of services to which the customer subscribes.
+
+##### 5.3.3.4.3 OSS, DHCP & TFTP servers
+
+The OSS system is responsible for:
+
+- MTA and service provisioning;
+- MTA code downloads and upgrades;
+- handling service change requests and dynamic reconfiguration of MTAs.
+
+A compromise of the OSS, DHCP or TFTP server can result in:
+
+- MTAs running illegal code, which may:
+  - intentionally introduce bugs or render the MTA completely inoperable;
+  - degrade voice communications performance on the IPCablecom or HFC network;
+  - configure the MTA with features to which the customer is not entitled;
+- MTAs configured with an identity and keys of another customer;
+- MTAs configured with service options for which the customer did not pay;
+- MTAs provisioned with a bad set of parameters that would make them perform badly or not perform at all.
+
+#### 5.3.3.5 PSTN Gateways
+
+##### 5.3.3.5.1 Media Gateway
+
+The MG is responsible for:
+
+- passing media packets between the IPCablecom network and the PSTN;
+
+- reporting statistics to the RKS.
+
+A compromise of the MG may result in:
+
+- service theft by reporting invalid information to the RKS;
+- loss of privacy on communications to/from the PSTN.
+
+##### **5.3.3.5.2 Signalling Gateway**
+
+The SG is responsible for translating call signalling between the IPCablecom network and the PSTN.
+
+A compromise of the SG may result in:
+
+- incorrect MTA identity reported to the PSTN;
+- unauthorized services enabled within the PSTN;
+- loss of PSTN connectivity;
+- unauthorized disclosure of customer identity, location (e.g., IP address), usage patterns and a list of services to which the customer subscribes.
+
+# **6 Security mechanisms**
+
+Unless explicitly stated otherwise, the following requirements apply to messages described by this Recommendation:
+
+- ASN.1 encoded messages and objects MUST conform to the Distinguished Encoding Rules per ITU-T Rec. X.690.
+- FQDNs used as components of principal names and principal identifiers MUST be rendered in lower case.
+- FQDNs MUST NOT include the root domain (i.e., they MUST NOT include a trailing dot).  
+All Kerberos messages in IPCablecom MUST utilize only UDP/IP.
+
+## **6.1 IPsec**
+
+### **6.1.1 Overview**
+
+IPsec provides network-layer security that runs immediately above the IP layer in the protocol stack. It provides security for the TCP or UDP layer and above. It consists of two protocols, IPsec ESP and IPsec AH, as specified in RFC 2401.
+
+IPsec ESP provides confidentiality and message integrity, IP header not included. IPsec AH provides only message integrity, but that includes most of the IP header (with the exception of some IP header parameters that can change with each hop). IPCablecom utilizes only the IPsec ESP protocol per RFC 2406, since authentication of the IP header does not significantly improve security within the IPCablecom architecture.
+
+Each protocol supports two modes of use: transport mode and tunnel mode. IPCablecom only utilizes IPsec ESP transport mode. For more detail on IPsec and these two modes, refer to RFC 2401. Note that in RFC 2401, all implementations of ESP are required to support the concept of Security Associations (SAs). RFC 2401 also provides a general model for processing IP traffic relative to SAs. Although particular IPsec implementations need not follow the details of this general model, the external behavior of any IPsec implementation must match the external behavior of the general model. This ensures that components do not accept traffic from unknown addresses and do not send or accept traffic without security (when security is required). IPCablecom components that implement IPsec are expected to provide behavior that matches the general model described in RFC 2401.
+
+### 6.1.2 IPCablecom profile for IPsec ESP (Transport mode)
+
+#### 6.1.2.1 IPsec ESP Transform Identifiers
+
+IPsec Transform Identifier (1 byte) is used by IKE to negotiate an encryption algorithm that is used by IPsec. A list of available IPsec Transform Identifiers is specified in RFC 2407. Within IPCablecom, the same Transform Identifiers are used by all IPsec key management protocols: IKE, Kerberos and application layer (embedded in IP signalling messages).
+
+Table 2 describes the IPsec Transform Identifiers (all of which use the CBC mode specified in RFC 2451) supported by IPCablecom.
+
+**Table 2 – IPsec ESP Transform Identifiers**
+
+| Transform ID | Value (Hex) | Key size (in bits) | MUST support | Description                                 |
+|--------------|-------------|--------------------|--------------|---------------------------------------------|
+| ESP_3DES     | 0x03        | 192                | Yes          | 3-DES in CBC mode                           |
+| ESP_RC5      | 0x04        | 128                | No           | RC5 in CBC mode                             |
+| ESP_IDEA     | 0x05        | 128                | No           | IDEA in CBC mode                            |
+| ESP_CAST     | 0x06        | 128                | No           | CAST in CBC mode                            |
+| ESP_BLOWFISH | 0x07        | 128                | No           | BLOWFISH in CBC mode                        |
+| ESP_AES      | 0x08        | 128                | No           | AES-128 in CBC mode with 128-bit block size |
+| ESP_NULL     | 0x0B        | 0                  | Yes          | Encryption turned off                       |
+
+The ESP\_3DES and ESP\_NULL Transform IDs MUST be supported. ESP\_AES is included as an optional encryption algorithm. For all of the above transforms, the CBC Initialization Vector (IV) is carried in the clear inside each ESP packet payload per RFC 2451. AES-128 (FIPS PUB 197) MUST be used in CBC mode with a 128-bit block size and a randomly generated Initialization Vector (IV). AES-128 requires 10 rounds of cryptographic operations.
+
+IKE allows negotiation of the encryption key size. Other IPsec key management protocols used by IPCablecom do not allow key size negotiation, and so for consistency a single key size is listed for each Transform ID. If in the future it is desired to increase the key size for one of the above algorithms, IKE will use the built-in key-size negotiation, while other key management protocols will utilize a new Transform ID for the larger key size.
+
+#### 6.1.2.2 IPsec ESP authentication algorithms
+
+The IPsec authentication algorithm (1 byte) is used by IKE to negotiate a packet-authentication algorithm that is used by IPsec. A list of available IPsec authentication algorithms is specified in RFC 2406. Within IPCablecom, the same authentication algorithms are used by all IPsec key management protocols: IKE, Kerberos, and application-layer (embedded in IP signalling messages).
+
+IPCablecom supports the IPsec authentication algorithms in Table 3.
+
+**Table 3 – IPsec authentication algorithms**
+
+| Authentication algorithm | Value (Hex) | Key size (in bits) | MUST support                    | Description                      |
+|--------------------------|-------------|--------------------|---------------------------------|----------------------------------|
+| HMAC-MD5                 | 0x01        | 128                | Yes (also required by RFC 2407) | First 12 bytes of the MD5 HMAC   |
+| HMAC-SHA                 | 0x02        | 160                | Yes                             | First 12 bytes of the SHA-1 HMAC |
+
+The HMAC-MD5-96 and HMAC-SHA-1-96 authentication algorithms MUST be supported.
+
+#### 6.1.2.3 Replay protection
+
+In general, IPsec provides an optional replay-protection service (anti-replay service). An IPsec sequence number outside of the current anti-replay window is flagged as a replay and the packet is rejected. When the anti-replay service is turned on, an IPsec sequence number cannot overflow and roll over to 0. Before that happens, a new Security Association must be created as specified in RFC 2406.
+
+Within IPCablecom Security Specification, the IPsec anti-replay service MUST be turned on at all times. This is regardless of which key management mechanism is used with the particular IPsec interface.
+
+#### 6.1.2.4 Key management requirements
+
+Within IPCablecom, IPsec is used on a number of different interfaces with different security and performance requirements. Because of this, several different key management protocols have been chosen for different IPCablecom interfaces. On some interfaces it is IKE (see 6.2), on other interfaces it is Kerberos/PKINIT (see 6.4.3.1).
+
+When IKE is not used for key management, an alternative key management protocol needs an interface to the IPsec layer in order to create/update/delete IPsec Security Associations. IPsec Security Associations (SAs) MUST be automatically established or re-established as required. This implies that the IPsec layer also needs a way to signal a key management application when a new Security Association needs to be set up (e.g., the old SA is about to expire or there is no SA on a particular interface).
+
+In addition, some network elements are required to run multiple key management protocols. In particular, the Application Server (such as a CMS) and the MTA MUST support multiple key management protocols. The MTA MUST support Kerberos/PKINIT on the MTA-CMS signalling interface. IKE MUST be supported on the CMS-CMTS and CMS-RKS interfaces.
+
+The PF\_KEY interface (see RFC 2367) SHOULD be used for IPsec key management within IPCablecom and would satisfy the above-listed requirements. For example, PF\_KEY permits multiple key management applications to register for rekeying events. When the IPsec layer detects a missing Security Association, it signals the event to all registered key management applications. Based on the Identity Extension associated with that Security Association, each key management application decides if it should handle the event.
+
+## 6.2 Internet Key Exchange (IKE)
+
+### 6.2.1 Overview
+
+IPCablecom utilizes RFC 2409 (IKE) as one of the key management protocols for IPsec. It is utilized on interfaces where:
+
+- there is not a very large number of connections;
+- the endpoints on each connection know about each other's identity in advance.
+
+Within IPCablecom, IKE key management is completely asynchronous to call signalling messages and does not contribute to any delays during communications set-up. The only exception would be some unexpected error, where a Security Association is unexpectedly lost by one of the endpoints.
+
+IKE is a peer-to-peer key management protocol. It consists of two phases. In the first phase, a shared secret is negotiated via a Diffie-Hellman key exchange. It is then used to authenticate the second IKE phase. The second phase negotiates another secret, used to derive keys for the IPsec ESP protocol.
+
+### **6.2.2 IPCablecom profile for IKE**
+
+#### **6.2.2.1 First IKE phase**
+
+There are several modes defined for authentication during the first IKE phase.
+
+##### **6.2.2.1.1 IKE authentication with signatures**
+
+In this mode, both peers MUST be authenticated with X.509 certificates and digital signatures. IPCablecom utilizes this IKE authentication mode on some IPsec interfaces. Whenever this mode is utilized, both sides MUST exchange X.509 certificates (although this is optional in RFC 2409).
+
+##### **6.2.2.1.2 IKE authentication with public-key encryption**
+
+IP Cablecom MUST NOT utilize this IKE authentication with public key encryption. In order to perform this mode of IKE authentication, the initiator must already have the responder's public key, which is not supported by IPCablecom.
+
+##### **6.2.2.1.3 IKE authentication with pre-shared keys**
+
+A key derived by some out-of-band (e.g., manual) mechanism is used to authenticate the exchange. IPCablecom utilizes this IKE authentication mode on some IPsec interfaces. IPCablecom does not specify the out-of-band method for deriving pre-shared keys.
+
+When using pre-shared keys, the strength of the system is dependent upon the strength of the shared secret. The goal is to keep the shared secret from being the weak link in the chain of security. This implies that the shared secret needs to contain as much entropy (randomness) as the cipher being used. In other words, the shared secret should have at least 128-160 bits of entropy. This means if the shared secret is just a string of random 8-bit bytes, then the key can be 16-20 bytes. If the shared secret is derived from a passphrase that is a string of random alpha-numerics (a-zA-Z0-9/+), then it should be at least 22-27 characters. This is because there are only 64 characters (6 bits) instead of 256 characters (8 bits) per 8-bit byte, which implies an expansion of 4/3 the length for the same amount of entropy. Both random 8-bit bytes and random 6-bit bytes assume truly random numbers. If there is any structure in the password/passphrase, like deriving from English, then even longer passphrases are necessary. A passphrase composed of English would need on the order of 60-100 characters, depending on mixing of case. Using English (or any language, for that matter) passphrases creates the problem that, if an attacker knows the language of the passphrase then they have less space to search. It is less random. This implies fewer bits of entropy per character, so a longer passphrase is required to maintain the same level of entropy.
+
+#### **6.2.2.2 Second IKE phase**
+
+In the second IKE phase, an IPsec ESP SA is established, including the IPsec ESP keys and ciphersuites. It is possible to establish multiple Security Associations with a single second-phase IKE exchange.
+
+First, a shared second-phase secret is established, and then all the IPsec keying material is derived from it using the one-way function specified in RFC 2409.
+
+The second-phase secret is built from encrypted nonces that are exchanged by the two parties. Another Diffie-Hellman exchange may be used in addition to the encrypted nonces. Within IPCablecom, IKE MUST NOT perform a Diffie-Hellman exchange in the second IKE phase in order to avoid the associated performance penalties.
+
+The second IKE phase is authenticated using a shared secret that was established in the first phase. Supported authentication algorithms are the same as those specified for IPsec in 6.1.2.2.
+
+#### 6.2.2.3 Encryption algorithms for IKE exchanges
+
+Both phase 1 and phase 2 IKE exchanges include some symmetrically-encrypted messages. The encryption algorithms supported as part of the IPCablecom profile for IKE MUST be the same algorithms identified in the IPCablecom profile for IPsec ESP in Table 2.
+
+#### 6.2.2.4 Diffie-Hellman groups
+
+IKE defines specific sets of Diffie-Hellman parameters (i.e., prime and generator) that may be used for the phase 1 IKE exchanges. These are called groups in RFC 2409. The use of Diffie-Hellman groups within IPCablecom IKE is identical to that specified in RFC 2409. Note that this is different from the requirements pertaining to the IPCablecom use of groups in PKINIT described in 6.4.2.1.1. Annex A provides details of the first and second Oakley groups.
+
+## 6.3 SNMPv3
+
+Any mention of SNMP in this Recommendation without a specific reference to the SNMP protocol version must be interpreted as SNMPv3.
+
+IPCablecom supports use of SNMPv2c coexistence for network management operations for devices provisioned under the Basic Flow or the Hybrid Flow. It also supports the SNMPv3/v2c coexistence for network management operations when the device is provisioned under the Secure Flow. Refer to the provisioning specification (ITU-T Rec. J.167) for the use of SNMP coexistence in IPCablecom. For any interface within the IPCablecom architecture utilizing SNMPv3 authentication MUST be turned on at all times and SNMPv3 privacy MAY also be utilized.
+
+In order to establish SNMPv3 keys, all IPCablecom SNMP interfaces SHOULD utilize Kerberized SNMPv3 key management (as specified in 6.5.4). In addition, SNMPv3 key management techniques specified in RFC 3414 MAY also be used.
+
+### 6.3.1 SNMPv3 Transform Identifiers
+
+The SNMPv3 Transform Identifier (1 byte) is used by Kerberized key management to negotiate an encryption algorithm for use by SNMPv3.
+
+For IPCablecom, the SNMPv3 Transform Identifiers in Table 4 MUST be supported.
+
+**Table 4 – SNMPv3 Transform Identifiers**
+
+| Transform ID | Value (Hex) | Key size (in bits) | MUST be supported | Description                                                                                            |
+|--------------|-------------|--------------------|-------------------|--------------------------------------------------------------------------------------------------------|
+| SNMPv3_DES   | 0x21        | 128                | Yes               | DES in CBC mode The first 64 bits are used as the DES Key and the remaining 64 are used as the pre-IV. |
+| SNMPv3_NULL  | 0x20        | 0                  | Yes               | Encryption turned off                                                                                  |
+
+The SNMPv3\_DES and the SNMPv3\_NULL Transform IDs MUST be supported. The DES encryption transform for SNMPv3 is specified in RFC 3414. Note that DES encryption does not provide strong privacy but is currently the only encryption algorithm specified by the SNMPv3 standard.
+
+### 6.3.2 SNMPv3 authentication algorithms
+
+SNMPv3 authentication algorithm (1 byte) is used by Kerberized key management to negotiate an SNMPv3 message authentication algorithm.
+
+For IPCablecom, the SNMPv3 authentication algorithms in Table 5 are supported (both of which are specified in RFC 3414):
+
+**Table 5 – SNMPv3 authentication algorithms**
+
+| Authentication algorithm | Value (Hex) | Key size (in bits) | MUST be supported               | Description |
+|--------------------------|-------------|--------------------|---------------------------------|-------------|
+| SNMPv3_HMAC-MD5          | 0x21        | 128                | Yes (also required by RFC 3414) | MD5 HMAC    |
+| SNMPv3_HMAC-SHA-1        | 0x22        | 160                | No (SHOULD be supported)        | SHA-1 HMAC  |
+
+The SNMPv3\_HMAC-MD5 authentication algorithm MUST be supported. The SNMPv3\_HMAC-SHA-1 authentication algorithm SHOULD be supported.
+
+## 6.4 Kerberos/PKINIT
+
+### 6.4.1 Overview
+
+IPCablecom utilizes the concept of Kerberized IPsec for signalling between an Application Server, such as the CMS, and the MTA. This refers to the ability to create IPsec security associations using keys derived from the subkeys exchanged using the Kerberos AP Request/AP Reply messages. On this interface, Kerberos (see IETF RFC 4120) is utilized with the PKINIT public key extension (also see IETF RFC 4556).
+
+Kerberized IPsec consists of three distinct phases:
+
+- 1) A client SHOULD obtain a TGT (Ticket Granting Ticket) from the KDC (Key Distribution Centre). Once the client obtains the TGT, it MUST use the TGT in the subsequent phase to authenticate to the KDC and obtain a ticket for the specific Application Server, e.g., a CMS.
+
+In Kerberos, tickets are symmetric authentication tokens encrypted with a particular server's key. (For a TGT, the server is the KDC.) Tickets are used to authenticate a client to a server. A PKI equivalent of a ticket would be an X.509 certificate. In addition to authentication, a ticket is used to establish a session key between a client and a server, where the session key is contained in the ticket.
+
+The logical function within the KDC that is responsible for issuing TGTs is referred to as an Authentication Server or AS.
+
+- 2) A client obtains a ticket from the KDC for a specific Application Server. In this phase, a client can authenticate with a TGT obtained in the previous phase. A client can also authenticate to the KDC directly using a digital certificate or a password-derived key, bypassing phase 1.
+
+The logical function within the KDC that is responsible for issuing Application Server tickets based on a TGT is referred to as the Ticket Granting Server (TGS). When the TGT is bypassed, it is the Authentication Server that issues the Application Server tickets.
+
+- 3) A client utilizes the ticket obtained in the previous phase to establish a pair of Security Parameters (one to send and one to receive) with the server. This is the only key management phase that is not already specified in an IETF standard. The previous two phases are part of standard Kerberos, while this phase defines new messages that tie together Kerberos key management and IPsec.
+
+Figure 4 illustrates the three phases of Kerberos-based key management for IPsec.
+
+![Sequence diagram showing the three phases of Kerberos-based key management for IPsec involving a Client, KDC, and Application Server.](7f5df81190b8dc50dad2604562ae0715_img.jpg)
+
+```
+
+sequenceDiagram
+    participant Client
+    participant KDC
+    participant AS as Application Server
+
+    Note left of Client: Phase 1
+    Client->>KDC: (Request a TGT)  
+AS Request
+    KDC-->>Client: (Return TGT)  
+AS Reply
+
+    Note left of Client: Phase 2
+    Client->>KDC: (Request an Application Server ticket) with:  
+TGS Request
+    Note right of Client: or
+    Client->>KDC: AS Request (if phase 1 is skipped)
+    KDC-->>Client: (Return Application Server ticket) with:  
+TGS Reply
+    Note right of Client: or
+    KDC-->>Client: AS Reply
+
+    Note left of Client: Phase 3
+    Client->>AS: AP Request
+    AS-->>Client: AP Reply
+  
+```
+
+The diagram illustrates the three phases of Kerberos-based key management for IPsec. It involves three main entities: Client, KDC (Key Distribution Center), and Application Server. Phase 1 involves the Client sending an AS Request (Request a TGT) to the KDC, which responds with an AS Reply (Return TGT). Phase 2 involves the Client sending a TGS Request (Request an Application Server ticket) to the KDC, which responds with a TGS Reply (Return Application Server ticket). Alternatively, if Phase 1 is skipped, the Client sends an AS Request to the KDC, which responds with an AS Reply. Phase 3 involves the Client sending an AP Request to the Application Server, which responds with an AP Reply. The diagram is labeled J.170\_F04 at the bottom right.
+
+Sequence diagram showing the three phases of Kerberos-based key management for IPsec involving a Client, KDC, and Application Server.
+
+**Figure 4 – Kerberos-based key management for IPsec**
+
+During the AS Request/AS Reply exchange (that can occur in either phase 1 or phase 2), the client and the KDC perform mutual authentication. In standard Kerberos, a client key that is shared with the KDC is used for this authentication (see 6.4.2.2). The same AS Request/AS Reply exchange may also be authenticated with digital signatures and certificates when the PKINIT public key extension is used (see 6.4.2). Both the TGT and the Application Server tickets used within IPCablecom have a relatively long lifetime (days or weeks). This is acceptable as 3-DES, a reasonably strong symmetric algorithm, is required by IPCablecom.
+
+IPCablecom utilizes the concept of a TGT (Ticket Granting Ticket), used to authenticate subsequent requests for Application Server tickets. The use of a TGT has two main advantages:
+
+- It limits the exposure of the relatively long-term client key (that is in some cases reused as the service key). This consideration does not apply to clients that use PKINIT.
+- It reduces the number of public key operations that are required for PKINIT clients.
+
+The Application Server ticket contains a symmetric session key, which MUST be used in phase 3 to establish a set of keys for the IPsec ESP protocol. The keys used by IPsec MUST expire after a configurable time-out period (e.g., 10 minutes). Normally, the same Application Server ticket SHOULD be used to automatically establish a new IPsec SA. However, there are instances where it is desirable to drop IPsec sessions after a Security Association time out and establish them on-demand later. This allows for improved system scalability, since an application server (e.g., CMS) does not need to maintain a SA for every client (e.g., MTA) that it controls. It also is possible that a group of application servers (e.g., CMS clusters) may control the same subset of clients (e.g., MTAs) for load balancing. In this case, the MTA is not required to maintain an SA with each CMS in that group. This clause provides specifications for how to automatically establish
+
+a new IPsec SA right before an expiration of the old one and how to establish IPsec SAs on-demand, when a signalling message needs to be sent.
+
+IPCablecom also utilizes the Kerberos protocol to establish SNMPv3 keys between the MTAs and the Provisioning Server. Kerberized SNMPv3 key management is very similar to the Kerberized IPsec key management and consists of the same phases that were explained above for Kerberized IPsec. Each MTA again utilizes the PKINIT extension to Kerberos to authenticate itself to the KDC with X.509 certificates.
+
+Once an MTA obtains its service ticket for the Provisioning Server, it utilizes the same protocol that is used for Kerberized IPsec to authenticate itself to the Provisioning Server and to generate SNMPv3 keys. The key management protocol is specified to allow application-specific data that has different profiles for SNMPv3 and IPsec. The only exception is the Rekey exchange that is specified for IPsec in order to optimize the MTA hand-off between the members of a CMS cluster. The Rekey exchange is not utilized for SNMPv3 key management.
+
+A recipient of any Kerberos message that does not fully comply with the IPCablecom requirements MUST reject the message.
+
+#### **6.4.1.1 Kerberos ticket storage**
+
+Kerberos clients that store tickets in persistent storage will be able to re-use the same Kerberos ticket after a reboot. In the event that PKINIT is used, this avoids the need to perform public key operations.
+
+A Kerberos client MUST NOT obtain a new TGT upon reboot if it possesses a valid service ticket.
+
+An MTA MUST store the Provisioning Server service ticket in persistent storage. An MTA MUST be capable of storing a minimum of  $\text{pktcMtaDevEndPntCount}+1$  CMS service tickets in persistent storage, where  $\text{pktcMtaDevEndPntCount}$  is the MIB object specifying the number of physical endpoints on the MTA. An MTA MUST store all CMS service tickets that correspond to active endpoints. This means that an MTA that reaches the maximum number of CMS service tickets that can be stored in persistent storage will not over-write CMS service tickets that correspond to active endpoints.
+
+Kerberos clients other than MTAs SHOULD retain service tickets in persistent storage.
+
+Note that Kerberos clients will need to store additional information in order to use and validate the ticket, such as the session key information, the client IP address, and the ticket validity period. Refer to 7.1 for additional information on re-using stored tickets.
+
+### **6.4.2 PKINIT exchange**
+
+Figure 5 illustrates how a client may use PKINIT to either obtain a TGT (phase 1) or a Kerberos ticket for an Application Server (phase 2).
+
+![Sequence diagram of PKINIT exchange between MTA and KDC. The MTA sends a PKINIT Request to the KDC, which includes the MTA & KDC or Application Server name, time, nonce, Diffie-Hellman parameters, signature, and MTA certificate. The KDC responds with a PKINIT Reply containing the TGT or service Ticket, KDC certificate, Diffie-Hellman parameters + nonce + signature, and session key + key validity period encrypted with DH key. The MTA then stores the Ticket and Session Key. A 'Service Key' is shown on the KDC side, and a 'Ticket, Session Key' is shown on the MTA side. The diagram is labeled J.170_05.](5eb69662cc4fa7d0d49b4eb22951c204_img.jpg)
+
+```
+
+sequenceDiagram
+    participant MTA
+    participant KDC
+    Note right of KDC: { Service Key }
+    MTA->>KDC: PKINIT Request:  
+MTA & KDC or Application Server name, time, nonce,  
+Diffie-Hellman parameters, signature,  
+MTA certificate
+    KDC-->>MTA: PKINIT Reply:  
+TGT or service Ticket,  
+KDC certificate  
+Diffie-Hellman parameters + nonce + signature,  
+session key + key validity period  
+encrypted with DH key
+    Note left of MTA: { Ticket, Session Key }
+    Note right of KDC: J.170_05
+  
+```
+
+Sequence diagram of PKINIT exchange between MTA and KDC. The MTA sends a PKINIT Request to the KDC, which includes the MTA & KDC or Application Server name, time, nonce, Diffie-Hellman parameters, signature, and MTA certificate. The KDC responds with a PKINIT Reply containing the TGT or service Ticket, KDC certificate, Diffie-Hellman parameters + nonce + signature, and session key + key validity period encrypted with DH key. The MTA then stores the Ticket and Session Key. A 'Service Key' is shown on the KDC side, and a 'Ticket, Session Key' is shown on the MTA side. The diagram is labeled J.170\_05.
+
+**Figure 5 – PKINIT exchange**
+
+The PKINIT Request is carried as a Kerberos pre-authenticator field inside an AS Request and the PKINIT Reply is a pre-authenticator inside the AS Reply. The syntax of the Kerberos AS Request/Reply messages and how pre-authenticators plug in is specified in IETF RFC 4120.
+
+In this clause, the PKINIT client is referred to as an MTA, as it is currently the only IPCablecom element that authenticates itself to the KDC with the PKINIT protocol. If in the future other IPCablecom elements will also utilize the PKINIT protocol, the same specifications will apply. IPCablecom use of the AS Request/AS Reply exchange without PKINIT is covered in 6.4.3.
+
+Figure 5 lists several important parameters in the PKINIT Request and Reply messages. These parameters are:
+
+#### **PKINIT Request**
+
+- MTA (Kerberos principal) name – found in the KDC-REQ-BODY Kerberos structure (see IETF RFC 4120). For the format used in IPCablecom, see 6.4.7.
+- KDC or Application Server (Kerberos principal) name – found in the KDC-REQ-BODY Kerberos structure (see IETF RFC 4120). For the format used in IPCablecom, see 6.4.6.
+- Time – found in the PKAuthenticator structure, specified by PKINIT (IETF RFC 4556).
+- Nonce – found in the PKAuthenticator structure, specified by PKINIT (IETF RFC 4556). There is also a second nonce in the KDC-REQ-BODY Kerberos structure.
+- Diffie-Hellman parameters, signature and MTA certificate – these are all specified by PKINIT (IETF RFC 4556) and their use in IPCablecom is specified in 6.4.2.1.1.
+
+#### **PKINIT Reply**
+
+- TGT or Application Server Ticket – found in the KDC-REP Kerberos structure (see IETF RFC 4120).
+- KDC Certificate, Diffie-Hellman parameters, signature – these are all specified by PKINIT (see IETF RFC 4556) and their use in IPCablecom is specified in 6.4.2.1.2.
+
+- Nonce – found in the KdcDHKeyInfo structure, specified by PKINIT (IETF RFC 4556). This nonce must be the same as the one found in the PKAuthenticator structure of the PKINIT Request. There is another nonce in EncKDCRepPart Kerberos structure (see IETF RFC 4120). This nonce must be the same as the one found in the KDC-REQ-BODY of the PKINIT Request.
+- Session key, key validity period – found in the EncKDCRepPart Kerberos structure (see IETF RFC 4120).
+
+In Figure 5, the PKINIT exchange is performed at long intervals, in order to obtain an (intermediate) symmetric session key. This session key is shared between the MTA and the server via the server's ticket, where the application server may be the KDC (in which case the ticket is the TGT).
+
+#### 6.4.2.1 PKINIT profile for IPCablecom
+
+A particular MTA implementation MUST utilize the PKINIT exchange to either obtain Application Server tickets directly, or obtain a TGT first and then use the TGT to obtain Application Server tickets. An MTA implementation MAY also support both uses of PKINIT, where the decision to get a TGT first or not is local to the MTA and is dependent on a particular MTA implementation. On the other hand, the KDC MUST be capable of processing PKINIT requests for both a TGT and for Application Server tickets.
+
+The PKINIT exchange occurs independent of the signalling protocol, based on the current Ticket Expiration Time (Ticket<sub>EXP</sub>) and on the PKINIT Grace Period (PKINIT<sub>GP</sub>). If the PKINIT client is an MTA and the ticket it currently possesses corresponds to the Provisioning Server in the MIB, a KDC for a REALM that currently exists in the REALM table, or a CMS that currently exists in the CMS table, the MTA MUST initiate the PKINIT exchange at the time: Ticket<sub>EXP</sub> – PKINIT<sub>GP</sub>. If the PKINIT client is an MTA and the ticket it currently possesses does not correspond to the Provisioning Server in the MIB, a KDC for a REALM that currently exists in the REALM table, or a CMS that currently exists in the CMS table, the MTA MUST NOT initiate a PKINIT exchange. On the interfaces where PKINIT<sub>GP</sub> is not defined, the MTA SHOULD perform PKINIT exchanges on-demand.
+
+In the case where PKINIT is used to obtain an Application Server ticket directly, the use of the grace period accounts for a possible clock skew between the MTA and the CMS or other application server. If the MTA is late with the PKINIT exchange, it still has until Ticket<sub>EXP</sub> before the Application Server starts rejecting the ticket. Similarly, if PKINIT is used to obtain a TGT, the grace period accounts for a possible clock skew between the MTA and the KDC.
+
+The PKINIT exchange stops after the MTA obtains a new ticket, and therefore does not affect existing security parameters between the MTA and the CMS or other application server. Synchronizing the PKINIT exchange with the AP Request/Reply exchange is not required as long as the AS Request/Reply exchange results in a valid, non-expired Kerberos ticket.
+
+The PKINIT Request/Reply messages contain public key certificates, which make them longer than a normal size of a UDP packet. In this case, large UDP packets MUST be sent using IP fragmentation.
+
+A KDC server SHOULD be implemented on a separate host, independent of the Application Server. This would mean that frequent PKINIT operations from some MTAs will not affect the performance of any of the application servers or the performance of those MTAs that do not require frequent PKINIT exchanges.
+
+Kerberos tickets MUST NOT be issued for a period of time that is longer than 7 days. The MTA clock MUST NOT drift more than 2.5 minutes within that period (7 days). The PKINIT Grace Period (PKINIT<sub>GP</sub>) MUST be at least 15 minutes.
+
+##### 6.4.2.1.1 PKINIT Request
+
+The PKINIT Request message (PA-PK-AS-REQ) in IETF RFC 4556 is defined as:
+
+```
+PA-PK-AS-REQ ::= SEQUENCE {  
+    signedAuthPack    [0] ContentInfo  
+    trustedCertifiers [1] SEQUENCE OF TrustedCas OPTIONAL,  
+    kdcCert         [2] IssuerAndSerialNumber OPTIONAL  
+    encryptionCert  [3] IssuerAndSerialNumber OPTIONAL  
+}
+```
+
+The following fields MUST be present in PA-PK-AS-REQ for IPCablecom (and all other fields MUST NOT be present):
+
+- `signedAuthPack` – a signed authenticator field, needed to authenticate the client. It is defined in Cryptographic Message Syntax identified by the `SignedData` OID:
+
+```
+{iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs7(7) 2}.
+```
+
+`SignedData` is defined as:
+
+```
+SignedData ::= SEQUENCE {  
+    version           CMSVersion,  
+    digestAlgorithms  DigestAlgorithmIdentifiers,  
+    encapContentInfo  EncapsulatedContentInfo,  
+    certificates      [0] IMPLICIT CertificateSet OPTIONAL,  
+    crls              [1] IMPLICIT CertificateRevocationLists OPTIONAL,  
+    signerInfos       SignerInfos  
+}
+```
+
+- `digestAlgorithms` – for now MUST contain an algorithm identifier for SHA-1. Other digest algorithms may optionally be supported in the future.
+- `encapContentInfo` – is of type `EncapsulatedContentInfo` that is defined by Cryptographic Message Syntax as:
+
+```
+EncapsulatedContentInfo ::= SEQUENCE {  
+    eContentType        eContentTypeContentType,  
+    eContent            [0] EXPLICIT OCTET STRING OPTIONAL  
+}
+```
+
+Here `eContentType` indicates the type of data and for PKINIT must be set to:
+
+```
+{iso(1) org(3) dod(6) internet(1) security(5) kerberosv5(2) pkinit(3)  
+    pkauthdata(1)}
+```
+
+`eContent` is a data structure of type `AuthPack` encoded inside an OCTET STRING:
+
+```
+AuthPack ::= SEQUENCE {  
+    pkAuthenticator     [0] PKAuthenticator,  
+    clientPublicValue   [1] SubjectPublicKeyInfo OPTIONAL  
+}
+```
+
+The optional `clientPublicValue` parameter inside the `AuthPack` MUST always be present for IPCablecom. (This parameter specifies the client's Diffie-Hellman public value.)
+
+```
+PKAuthenticator ::= SEQUENCE {  
+    cusec           [0] INTEGER,  
+                    -- for replay prevention as in RFC 4120  
+    ctime           [1] KerberosTime,  
+                    -- for replay prevention as in RFC 4120  
+    nonce           [2] INTEGER,  
+                    -- zero only if client will accept  
+                    -- cached DH parameters from KDC;  
+                    -- must be non-zero otherwise  
+}
+```
+
+```
+
+pachecksum      [3]  Checksum
+                    -- Checksum over KDC-REQ-BODY
+                    -- Defined by Kerberos spec
+}
+
+```
+
+The pachecksum field MUST use the Kerberos checksum type rsa-md5, a plain MD5 checksum over the KDC-REQ-BODY.
+
+The nonce field MUST be non-zero, indicating that the client does not support the caching of Diffie-Hellman values and their expiration.
+
+- certificates – required by IPCablecom. This field MUST contain an MTA Device Certificate and an MTA Manufacturer Certificate. This field MUST NOT contain any other certificates. All IPCablecom certificates are X.509 certificates for RSA Public keys as specified in clause 8.
+- crls – MUST NOT be filled in by the MTA.
+- signerInfos – MUST be a set with exactly one member that holds the MTA signature. This signature is a part of a SignerInfo data structure defined within the Cryptographic Message Syntax. All optional fields in this data structure MUST NOT be used in IPCablecom. The digestAlgorithm MUST be set to SHA-1:
+
+```
+iso(1) identified-organization(3) oiw(14) secsig(3) algorithm(2) 26
+```
+
+and the signatureAlgorithm MUST be set to rsaEncryption:
+
+```
+iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 1
+```
+
+PKINIT allows an Ephemeral-Ephemeral Diffie-Hellman exchange as part of the PKINIT Request/Reply sequence. (Ephemeral-Ephemeral means that both parties during each exchange randomly generate the Diffie-Hellman private exponents.) The Kerberos session key is returned to the MTA in the PKINIT Reply, encrypted with a secret that is derived from the Diffie-Hellman exchange. Within IPCablecom, the Ephemeral-Ephemeral Diffie-Hellman MUST be supported.
+
+The IKE specification in RFC 2409 defines Diffie-Hellman parameters as Oakley groups. Within the IPCablecom PKINIT profile the 2nd Oakley group MUST be supported and the 1st Oakley group MAY also be supported. Annex A provides details of the first and second Oakley groups.
+
+When generating Diffie-Hellman private keys, a device MUST generate a key of length at least 144 bits when the first Oakley group is used and MUST generate a key of length at least 164 bits when the second Oakley group is used.
+
+For further details of PKINIT, please refer to IETF RFC 4556.
+
+Additionally, PKINIT supports a Static-Ephemeral Diffie-Hellman exchange, where the client is required to possess a Diffie-Hellman certificate in addition to an RSA certificate. This mode MUST NOT be used within IPCablecom.
+
+PKINIT also allows a single client RSA key to be used both for digital signatures and for encryption – wrapping the Kerberos session key in the PKINIT Reply. This mode MUST NOT be used within IPCablecom.
+
+PKINIT has an additional option for a client to use two separate RSA keys – one for digital signatures and one for encryption. This mode MUST NOT be used within IPCablecom.
+
+Upon receipt of a PA-PK-AS-REQ, the KDC MUST:
+
+- 1) check the validity of the certificate chain (MTA Device Certificate, MTA Manufacturer Certificate, MTA Root Certificate);
+- 2) check the validity of the signature in the (single) SignerInfo field;
+- 3) check the validity of the checksum in the PKAuthenticator.
+
+##### 6.4.2.1.2 PKINIT Reply
+
+The PKINIT Reply message (PA-PK-AS-REP) in IETF RFC 4556 is defined as follows:
+
+```
+PA-PK-AS-REP ::= CHOICE {  
+    dhSignedData [0] ContentInfo,  
+    encKeyPack   [1] ContentInfo,  
+}
+```
+
+IPCablecom MUST use only the dhSignedData choice, which is needed for a Diffie-Hellman exchange.
+
+The value of the Kerberos session key is not present in PA-PK-AS-REP. It is found in the encrypted portion of the AS Reply message that is specified in IETF RFC 4556. The AS Reply MUST be encrypted with 3-DES CBC, where the corresponding Kerberos etype value MUST be des3-cbc-md5. Other encryption types may be supported in the future.
+
+The client MUST use PA-PK-AS-REP to determine the encryption key used on the AS Reply. This PKINIT Reply contains the KDC's Diffie-Hellman public value that is used to generate a shared secret (part of the key agreement). This shared secret is used to encrypt/decrypt the private part of the AS Reply.
+
+- dhSignedData – dhSignedData is identified by the SignedData oid:
+
+```
+{iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs7(7) 2}
+```
+
+Within SignedData (specified in 6.4.2.1.1):
+
+- digestAlgorithms for now MUST contain an algorithm identifier for SHA-1. Other digest algorithms may optionally be supported in the future.
+- encapContentInfo is of type pkdhkeydata, where eContentType contains the following OID value:
+
+```
+{iso(1) org(3) dod(6) internet(1) security(5) kerberosv5(2) pkinit(3)  
+    pkdhkeydata(2)}
+```
+
+eContent is of type KdcDHKeyInfo (encoded inside an OCTET STRING):
+
+```
+KdcDHKeyInfo ::= SEQUENCE {  
+    subjectPublicKey [0] BIT STRING, -- used only when utilizing Diffie-Hellman  
+                                     -- Equals public exponent (g^a mod p)  
+                                     -- INTEGER encoded as payload of  
+                                     -- BIT STRING  
+    nonce          [1] INTEGER,     -- Binds response to the request  
+                                     -- Exception: Set to zero when KDC  
+                                     -- is using a cached DH value  
+    dhKeyExpiration [2] KerberosTime OPTIONAL  
+                                     -- Expiration time for KDC's cached  
+                                     -- DH value
+```
+
+The nonce MUST be the same nonce that was passed in by the client in the PKINIT Request.
+
+- The subjectPublicKey MUST be the Diffie-Hellman public value generated by the KDC. The Diffie-Hellman-derived key is used to directly encrypt part of the AS Reply. The requirements on the length of the Diffie-Hellman private exponent are as defined in 6.4.2.1.1.
+- The dhKeyExpiration MUST not be present as caching of Diffie-Hellman values is not permitted.
+
+- certificates – required by IPCablecom. This field MUST contain a KDC certificate. If a Local System CA issued the KDC certificate, then the corresponding Local System CA Certificate MUST also be present. The Service Provider CA Certificate MUST also be present in this field. This field MAY contain the Service Provider Root CA certificate (refer to 8.2.1 for validating the Service Provider Root CA certificate if it is included in the PKINIT Reply). This field MUST NOT contain any other certificates. If the MTA is configured with a specific service provider name, it MUST verify that the Service Provider name is identical to the value of the OrganizationName attribute in the subjectName of the Service Provider certificate. If the Local System Certificate is present, then the MTA MUST verify that the Service Provider name is identical to the value of the OrganizationName attribute in the subjectName of the Local System Certificate. In addition to standard certificate verification rules specified in RFC 2459, an MTA MUST verify that the KDC certificate includes a subjectAltName extension in the format specified in 8.2.3.4.1. The MTA MUST verify that the extension contains a valid KDC principal name and that the KDC realm in this extension is identical to the server realm name in the encrypted portion of the AS Reply message (EncKDCRepPart).
+- crls – this optional field MAY be filled in by the KDC.
+- signerInfos – MUST be a set with exactly one member that holds the KDC signature. This signature is a part of a SignerInfo data structure defined within the Cryptographic Message Syntax. All optional fields in this data structure MUST NOT be used in IPCablecom. The digestAlgorithm MUST be set to SHA-1:
+
+```
+iso(1) identified-organization(3) oiw(14) secsig(3) algorithm(2) 26
+```
+
+The signatureAlgorithm MUST be set to rsaEncryption:
+
+```
+iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs-1(1) 1
+```
+
+Upon receipt of a PA-PK-AS-REP, the client MUST:
+
+- 1) check the value of the nonce in the eContent field;
+- 2) check the validity of the KDC certificate;
+- 3) check the validity of the signature in the SignerInfo field.
+
+###### 6.4.2.1.2.1 PKINIT error messages
+
+In the case that a PKINIT Request is rejected, instead of a PKINIT Reply the KDC MUST return a Kerberos error message of type KRB\_ERROR, as defined in IETF RFC 4556. Any error code that is defined in IETF RFC 4556 for PKINIT MAY be returned.
+
+- The KRB\_ERROR MUST use typed-data of REQ-NONCE to bind the error message to the nonce from the KDC-REQ-BODY portion of the AS-REQ message. This error message MUST NOT include the optional e-cksum member that would contain a keyed checksum of the error reply. The use of this field is not possible during the PKINIT exchange, since the client and the KDC do not share a symmetric key.
+
+When a client receives an error message from the KDC, in some cases this Recommendation calls for the client to take some recovery steps and then send a new AS Request or TGS Request. When a client is responding to an error message, it is not a retry and MUST NOT be considered to be part of the client's back-off and retry procedure specified in 6.4.8. The client MUST reset its timers accordingly, to reflect that the new request in response to an error message is not a retry.
+
+Although this Recommendation calls for a KDC to return some specific error codes under certain error conditions, in the case when a KDC is repeatedly getting the same error from the same client IP address, it MAY at some point choose to stop sending back any further replies (errors or otherwise) to this client.
+
+###### 6.4.2.1.2.1.1 Clock skew error
+
+When the KDC clock and the client clock are off by more than the limit for a clock skew, an error code KRB\_AP\_ERR\_SKEW MUST be returned. The value for the maximum clock skew allowed by the KDC MUST NOT exceed 5 minutes. The optional client's time in the KRB\_ERROR MUST be filled out, and the client MUST compute the difference (in seconds) between the two clocks based upon the client and server time contained in the KRB\_ERROR message. The client SHOULD store this clock difference in non-volatile memory and MUST use it to adjust Kerberos timestamps in subsequent KDC request messages (AS Request and TGS Request) by adding the clock skew to its local clock value each time. The client MUST maintain a separate clock skew value for each realm. The clock skew values are intended for uses only within the Kerberos protocol and SHOULD NOT otherwise affect the value of the local clock (since a clock skew is likely to vary from realm to realm).
+
+In the case that a KDC request fails due to a clock skew error, a client MUST immediately retry after adjusting the Kerberos timestamp inside the KDC Request message.
+
+In addition, the MTA MUST validate the time offset returned in the clock skew error, to make sure that it does not exceed a maximum allowable amount. This maximum time offset MUST NOT exceed 1 hour. This MTA check against a maximum time offset protects against an attack in which a rogue KDC attempts to fool an MTA into accepting an expired KDC certificate.
+
+##### 6.4.2.1.3 Pre-authenticator for Provisioning Server Location
+
+An AS Request sent by the MTA MUST include this PROV-SRV-LOCATION pre-authenticator that the KDC can use to locate the Provisioning Server.
+
+The pre-authenticator type MUST be -1 (according to IETF RFC 4120, the negative type is used for application-specific pre-authenticators). Its ASN.1 encoding is specified as:
+
+```
+PROV-SRV-LOCATION ::= GeneralString
+                    -- Provisioning Server's FQDN
+```
+
+#### 6.4.2.2 Profile for the Kerberos AS Request/AS Reply messages
+
+As mentioned earlier, the PKINIT Request and Reply are pre-authenticator fields embedded into the AS Request/AS Reply messages. The IPCablecom-specific PROV-SRV-LOCATION pre-authenticator MUST be used in combination with PKINIT. All other pre-authenticators MUST NOT be used in combination with PKINIT.
+
+The optional fields enc-authorization-data, additional-tickets and rtime in the KDC-REQ-BODY MUST NOT be present in the AS Request. All other optional fields in the AS Request MAY be present for IPCablecom. The client MUST NOT set any of the KDCOptions in the AS-REQUEST, except that the DISABLE-TRANSITED-CHECK option MAY be set.
+
+The MTA MUST include its IP address in the optional addresses field of the KDC-REQ-BODY. The KDC MUST verify that the addresses field in the KDC-REQ-BODY contains exactly one IP address and that it is identical to the IP address in the IP header of the AS Request. After the KDC validates the addresses field, it MUST include it in the caddr fields of the issued ticket and the AS Reply. The KDC MUST reject an AS Request that does not include the MTA's IP address. In this case the KDC MUST return a KDC\_ERR\_POLICY error code.
+
+If a KDC receives an AS-REQ message in which any of the KDCOptions are set, except for the DISABLE-TRANSITED-CHECK option, the KDC MUST return an error with the error code KDC\_ERR\_POLICY.
+
+In the AS Reply, key-expiration, starttime, and renew-till optional fields MUST NOT be present. The session key contained in the AS-REPLY (which MUST be identical to the session key in the ticket) MUST be etype des3-cbc-md5.
+
+The encrypted part of the AS Reply is of the type EncryptedData. The ASN.1 definition of EncryptedData that is used inside multiple Kerberos objects is missing from the Kerberos revisions IETF RFC 4120. In all cases, EncryptedData MUST be DER-encoded with EXPLICIT tags as the following ASN.1 structure:
+
+```
+EncryptedData ::= SEQUENCE {  
+    etype [0] INTEGER, -- EncryptionType  
+    kvno [1] INTEGER OPTIONAL, -- service key  
+    -- version number  
+    cipher [2] OCTET STRING -- ciphertext  
+}
+```
+
+When EncryptedData contains ciphertext that is encrypted with a service key, the 'kvno' element MUST be present and MUST identify the version of the service key that was used to encrypt the data. When EncryptedData contains ciphertext that is encrypted with a Kerberos session key or with a reply key derived from a PKINIT pre-authenticator, the 'kvno' element MUST NOT be present. This is the case for the encrypted portion of the AS Reply.
+
+The encryption type for an encrypted portion of the AS Reply MUST be set to des3-cbc-md5. In order to generate the value of the 'cipher' element of the EncryptedData, the following data MUST be concatenated and processed in the following sequence before being encrypted with 3-DES CBC, IV=0:
+
+- 8-byte random byte sequence, called a confounder;
+- an MD5 checksum, which is the MD5 hash of the concatenation of the three quantities (the confounder + sixteen NULL octets + the text to be encrypted [not including any padding]);
+- AS Reply part that is to be encrypted;
+- random padding up to a multiple of 8.
+
+Upon receipt of an AS-REPLY, the client MUST check the validity of the checksum in the encrypted portion of the AS-REPLY.
+
+#### 6.4.2.3 Profile for Kerberos tickets
+
+In Kerberos tickets, authorization-data, starttime and renew-till optional fields MUST NOT be present. The optional caddr field MUST be present when requested in an AS-REQUEST or when present in a TGT of a TGS Request (see IETF RFC 4120). The only ticket flags that are currently supported within IPCablecom are the INITIAL, PRE-AUTHENT and TRANSITED-POLICY-CHECKED flags. If the KDC receives any request that would otherwise cause it to set any other flag, it MUST return an error with the error code KDC\_ERR\_POLICY. The KDC MUST NOT generate tickets with any other flags set. The session key contained in the ticket (which MUST be identical to the session key in the AS-REPLY) MUST be etype des3-cbc-md5. Since the transited encoding information normally required by PKINIT is not used in IPCablecom, a KDC MAY choose to leave as a null string the 'contents' field of the TransitedEncoding portion of a ticket issued in response to a PKINIT request.
+
+The encrypted part of the Kerberos ticket MUST be encrypted with the encryption type set to des3-cbc-md5, using the same procedure as described in 6.4.2.2.
+
+Upon receipt of a ticket for a service, the server MUST:
+
+- 1) check the validity of the checksum in the encrypted portion of the ticket;
+- 2) check that the ticket has not expired.
+
+Currently, all the service keys are pre-shared using an out-of-band mechanism between the KDC and the device providing the service. In the future, IPCablecom may support a method that does not require these keys to be pre-shared.
+
+### 6.4.3 Symmetric Key AS Request/AS Reply exchange
+
+In IPCablecom, a Kerberos client MAY use standard symmetric-key authentication (with a client key) during the AS Request/AS Reply exchange. Also, in IPCablecom, a client not utilizing PKINIT is, at the same time, an Application Server for which other clients might obtain tickets. This means that an IPCablecom entity may utilize the same symmetric key for both client authentication and for decrypting its service tickets.
+
+The Kerberos AS Request/AS Reply exchange, in general, is allowed to occur with no client authentication. The client, in those cases, would authenticate itself later by proving that it is able to decrypt the AS Reply with its symmetric key and make use of the session key.
+
+Such use of Kerberos is not acceptable within IPCablecom. This approach would allow a rogue client to continuously generate AS Requests on behalf of other clients and receive the corresponding AS Replies. Although this rogue client would be unable to decrypt each AS Reply, it will know some of the fields that it should contain. This, and the availability of the matching encrypted AS Replies, would aid an attacker in the discovery of another client's key with cryptanalysis.
+
+Therefore, IPCablecom requires that whenever an AS Request is not using a PKINIT pre-authenticator, it MUST instead use a different pre-authenticator, of type PA-ENC-TS-ENC. This pre-authenticator is specified as:
+
+```
+PA-ENC-TS-ENC ::= SEQUENCE {  
+    patimestamp      [0]  KerberosTime,  
+                        -- client's time  
+    pausec           [1]  INTEGER OPTIONAL  
+    pachecksum       [2]  CheckSum OPTIONAL  
+                        -- keyed checksum of  
+                        -- KDC-REQ-BODY  
+}
+```
+
+The PA-ENC-TS-ENC pre-authenticator MUST be encrypted with the client key using the encryption type des3-cbc-md5, as described in 6.4.2.2. All optional fields inside PA-ENC-TS-ENC MUST be present for IPCablecom. The pachecksum field MUST be a keyed checksum of type des3-cbc-md5 and MUST be validated by the KDC. The encrypted timestamp is used by the KDC to authenticate the client. At the same time, the timestamp inside this pre-authenticator is used to prevent replays. The KDC checks for replays upon the receipt of this pre-authenticator; this is similar to the checking performed by an Application Server upon receipt of an AP Request message.
+
+If the timestamp in the PA-ENC-TS-ENC pre-authenticator differs from the current KDC time by more than pktcKdcToMtaMaxClockSkew then KDC MUST reply with a clock skew error message and the client MUST respond to this error message as specified in 6.4.2.1.2.1.1.
+
+If the realm, target server name (e.g., the name of the KDC), along with the client name, time and microsecond fields from the PA-ENC-TS-ENC pre-authenticator match any recently-seen such tuples, the KRB\_AP\_ERR\_REPEAT error MUST be returned. The KDC MUST remember any such pre-authenticator presented within acceptable clock skew period, so that a replay attempt is guaranteed to fail.
+
+If the Application Server loses track of any authenticator presented within acceptable clock skew period, it MUST reject all requests until the acceptable clock skew interval has passed.
+
+Symmetric-key AS Request/AS Reply exchange is illustrated in Figure 6.
+
+![Sequence diagram of Symmetric-key AS Request/AS Reply exchange between a Client and a KDC.](ae0a735d106290c594b0bafb1f5e72e7_img.jpg)
+
+The diagram illustrates the interaction between a Client and a KDC for symmetric-key AS Request/AS Reply exchange. The Client sends an AS Request to the KDC, which includes the client name, KDC name or other server name, a nonce, and a PA-ENC-TS-ENC pre-authenticator (client time encrypted with the client key). The KDC responds with an AS Reply containing a TGT or other server ticket, a nonce + session key + key validity period, all encrypted with the client key. The Client then extracts the Ticket and Session Key. A Service Key is also shown as being associated with the KDC.
+
+```
+
+sequenceDiagram
+    participant Client
+    participant KDC
+    Note right of KDC: { Service Key }
+    Client->>KDC: AS Request:
+        client name
+        KDC name or other server name,
+        nonce,
+        PA-ENC-TS-ENC pre-authenticator:
+        client time encrypted with the client key
+    KDC-->>Client: AS Reply:
+        TGT or other server ticket,
+        nonce + session key + key validity period
+        encrypted with the client key
+    Note left of Client: { Ticket, Session Key }
+    Note right of KDC: J.170_F06
+  
+```
+
+Sequence diagram of Symmetric-key AS Request/AS Reply exchange between a Client and a KDC.
+
+**Figure 6 – Symmetric-key AS Request/AS Reply exchange**
+
+#### 6.4.3.1 Profile for the Symmetric-key AS Request/AS Reply exchanges
+
+The content of the AS Request/AS Reply messages is the same as in the case of the PKINIT pre-authentication (see 6.4.2.2) with the exception of the type of the pre-authenticator that is used.
+
+In general, clients using a symmetric-key form of the AS Request/AS Reply exchange are not required to always possess a valid TGT or a valid Application Server ticket. A client MAY obtain both a TGT and Application Server tickets on demand, as they are needed for the key management with the Application Server.
+
+However, there may be cases where a client is required to quickly switch between servers for load balancing and the additional symmetric-key exchanges with the KDC are undesirable. In those cases, a client MAY be optimized to obtain tickets in advance, so that the key management would take only a single round trip (AP Request/AP Reply exchange).
+
+In the case that the KDC rejects the AS Request, it returns a KRB\_ERROR message instead of the AS Reply, as specified in IETF RFC 4120. The KRB\_ERROR MUST use typed-data of REQ-NONCE to bind the error message to the nonce from the AS-REQ message. This error message MUST include the optional e-cksum member that would contain an rsa-md5-des3 keyed checksum of the error reply, unless pre-authentication failed to prove knowledge of the shared symmetric key in which case the e-cksum MUST NOT be used.
+
+The rsa-md5-des3 checksum MUST be computed as follows:
+
+- 1) Prepend the message with an 8-byte random byte sequence, called a confounder.
+- 2) Take an MD5 hash of the result of step 1.
+- 3) Prepend the hash with the same 8-byte confounder.
+- 4) Take the 3DES session key from the ticket and XOR each byte with F0.
+
+- 5) Use 3DES in CBC mode to encrypt the result of step 3, using the key in step 4 and with IV (initialization vector) = 0.
+
+Once a client receives an AS Reply, it SHOULD save both the obtained ticket and the session key information (found in the enc-part member of the reply) in non-volatile memory. Thus, the client will be able to reuse the same Kerberos ticket after a reboot, avoiding the need to perform the AS Request again.
+
+Kerberos tickets MUST NOT be issued for a period of time that is longer than 7 days (same as for PKINIT exchanges).
+
+Upon receipt of a KRB\_ERROR that contains an e-cksum field, the recipient MUST verify the validity of the checksum.
+
+### 6.4.4 Kerberos TGS Request/TGS Reply exchange
+
+In the cases where a client obtained a TGT, that TGT is then used in the TGS Request/TGS Reply exchange to obtain a specific Application Server ticket. This is part of the Kerberos standard, as specified in IETF RFC 4120.
+
+A TGS Request includes a KRB\_AP\_REQ data structure (the same structure used in an AP Request: see 6.4.4.1). This data structure contains the TGT as well as an authenticator that is used by the client to prove the possession of the corresponding session key. The TGS Reply has the same format as an AS Reply, except that it is encrypted using a different key – the session key from the TGT.
+
+Figure 7 illustrates the TGS Request/TGS Reply exchange:
+
+![Sequence diagram of Kerberos TGS Request/TGS Reply exchange between a Client and a KDC.](5c3dd31372f59e15250f0ab1613ca485_img.jpg)
+
+The diagram illustrates the interaction between a Client and a KDC for the TGS Request/TGS Reply exchange. At the top, the Client holds a TGT and TGT Session Key, while the KDC holds the TGS Service Key and Target Service Key. The Client sends a TGS Request to the KDC, containing the target server name and realm, a nonce, and a KRB\_AP\_REQ pre-authenticator. The pre-authenticator includes the TGT and a client name + time + hash encrypted with the TGT session key. The KDC responds with a TGS Reply containing the Target server ticket, nonce + target srv sess key + key validity period, encrypted with the TGT session key. The Client then receives the Target Server Ticket and Target Server Session Key. The diagram is labeled J.170\_F07 at the bottom right.
+
+```
+
+sequenceDiagram
+    participant Client
+    participant KDC
+    Note left of Client: { TGT, TGT Session Key }
+    Note right of KDC: { TGS Service Key, Target Service Key }
+    Client->>KDC: TGS Request: target server name and realm, nonce, KRB_AP_REQ pre-authenticator (TGT, client name + time + hash encrypted with TGT session key)
+    KDC-->>Client: TGS Reply: Target server ticket, nonce + target srv sess key + key validity period encrypted with the TGT session key
+    Note left of Client: { Target Server Ticket, Target Server Session Key }
+  
+```
+
+Sequence diagram of Kerberos TGS Request/TGS Reply exchange between a Client and a KDC.
+
+Figure 7 – Kerberos TGS Request/TGS Reply exchange
+
+Figure 7 lists several important parameters in the TGS Request and Reply messages. These parameters are:
+
+#### **TGS Request**
+
+- Target server (principal) name and realm, nonce – found in the KDC-REQ-BODY Kerberos structure (see IETF RFC 4120).
+- TGS pre-authenticator – found in the KDC-REQ Kerberos structure, inside the padata field (see IETF RFC 4120). The pre-authenticator type in this case is PA-TGS-REQ.
+- KRB\_AP\_REQ – the value of the pre-authenticator of type PA-TGS-REQ.
+- TGT – inside the KRB\_AP\_REQ.
+- Client name, time – inside the Kerberos Authenticator structure, which is embedded in an encrypted form in the KRB\_AP\_REQ.
+
+#### **TGS Reply**
+
+- Target server ticket – found in the KDC-REP Kerberos structure (see IETF RFC 4120).
+- Target server session key, nonce, key validity period – found in the EncKDCRepPart Kerberos structure (see IETF RFC 4120).
+
+In general, the TGS Request/Reply exchange may be performed on-demand – whenever an Application Server ticket is needed to establish Security Parameters. If the client is an MTA and a ticket it currently possesses corresponds to the Provisioning Server in the MIB or a CMS that currently exists in the CMS table, it **MUST** initiate the TGS Request/Reply exchange at the time:  $\text{Ticket}_{\text{EXP}} - \text{TGS}_{\text{GP}}$ . Here,  $\text{Ticket}_{\text{EXP}}$  is the expiration time of the current Application Server ticket and  $\text{TGS}_{\text{GP}}$  is the TGS Grace Period. If the client is an MTA and the ticket it currently possesses does not correspond to the Provisioning Server in the MIB or a CMS that currently exists in the CMS table, the MTA **MUST NOT** initiate a PKINIT exchange.
+
+The validity of the Application Server tickets **MUST NOT** extend beyond the expiration time of the TGT that was used to obtain the server ticket.
+
+#### **6.4.4.1 TGS Request profile**
+
+The optional padata element in the KDC-REQ data structure **MUST** consist of exactly one element – a pre-authenticator of type PA-TGS-REQ. The value of this pre-authenticator is the KRB\_AP\_REQ data structure. Within KRB\_AP\_REQ:
+
+- 1) options in the ap-options field **MUST NOT** be present;
+- 2) the ticket is the TGT;
+- 3) the encrypted authenticator **MUST** contain the checksum field – an MD5 checksum of the ASN.1 encoding of the KDC-REQ-BODY data structure. It **MUST NOT** contain any other optional fields;
+- 4) the authenticator **MUST** be encrypted using 3-DES CBC with the following Kerberos etype: value des3-cbc-md5 as specified in 6.4.2.2.
+
+The optional fields from enc-authorization-data, additional-tickets and rtime in the KDC-REQ-BODY **MUST NOT** be present in the TGS Request. The optional field cname **SHOULD NOT** be present. All other optional fields in the TGS Request **MAY** be present for IPCablecom. The KDC **MUST** reject a TGT that has any ticket flags set, apart from the flags INITIAL, PRE-AUTHENT or TRANSITED-POLICY-CHECKED. If the KDC receives any request that would otherwise cause it to set any flag in the service ticket, apart from the PRE-AUTHENT and TRANSIT-POLICY-CHECKED flags, it **MUST** return an error with the error code KDC\_ERR\_POLICY. The KDC **MUST NOT** generate TGT-based service tickets with any other flags set.
+
+If the TGT contains a caddr field, the KDC MUST verify that it is a single IP address and that it is identical to the IP address in the IP header of the TGS Request. The KDC MUST reject TGS Requests from an MTA with a TGT that does not include the MTA's IP address, returning a KDC\_ERR\_POLICY error code (refer to 6.4.4.3)
+
+Upon receipt of a TGS Request, the KDC MUST:
+
+- 1) check the validity of the TGT;
+- 2) check the validity of the checksum in the authenticator.
+
+#### 6.4.4.2 TGS Reply profile
+
+In the TGS Reply, key-expiration, starttime, and renew-till optional fields MUST NOT be present. The encrypted part of the TGS Reply MUST be encrypted with the encryption type set to des3-cbc-md5, using the same procedure as described in 6.4.2.2.
+
+Upon receipt of a TGS Reply, the client MUST:
+
+- 1) use the value of the nonce to bind the reply to the corresponding TGS Request;
+- 2) check the validity of the checksum in the encrypted portion of the TGS Reply.
+
+#### 6.4.4.3 Error reply
+
+If the KDC is able to successfully parse the TGS Request and the TGT that is inside of it, but the TGS Request is rejected, it MUST return a Kerberos error message of type KRB\_ERROR, as defined in IETF RFC 4120. The error message MUST include the optional e-cksum member, which is the keyed hash over the KRB\_ERROR message. The checksum type MUST be rsa-md5-des3, calculated using the procedure described in 6.4.3.1.
+
+The KRB\_ERROR MUST also include typed-data of REQ-NONCE to bind the error message to the nonce from the TGS-REQ message.
+
+Upon receipt of a KRB\_ERROR, the client MUST check the validity of the checksum.
+
+### 6.4.5 Kerberos server locations and naming conventions
+
+#### 6.4.5.1 Kerberos realms
+
+A realm name MAY use the same syntax as a domain name, however Kerberos Realms MUST be in all capitals. For a full specification of Kerberos realms, refer to IETF RFC 4120.
+
+#### 6.4.5.2 KDC
+
+Kerberos principal identifier for the local KDC when it is in a role of issuing tickets is always: krbtgt/<realm>@<realm>, where <realm> is the Kerberos realm corresponding to the particular IPCablecom zone. This is the service name listed inside a TGT.
+
+A Kerberos client MUST query KDC FQDNs for a particular realm name using DNS SRV records, as specified in RFC 2782 and as shown below:
+
+<Service Name>.<Protocol>.<Name> TTL Class SRV Priority Weight Port Target
+
+where:
+
+- the Service Name for Kerberos in IPCablecom MUST be "\_kerberos";
+- the Protocol for Kerberos in IPCablecom MUST be "\_udp";
+- the Name MUST be the Kerberos realm name that this record corresponds to;
+- TTL, Class, SRV, Priority, Weight, Port, and Target have the standard meaning as defined in RFC 2782.
+
+For example, assume the presence of a realm, PACKETCABLE.COM, with two KDCs: kdc1.packetcable.com and kdc2.packetcable.com. These KDCs have different priorities. The DNS SRV records in this case would be:
+
+```
+_kerberos._udp.PACKETCABLE.COM.      86400      IN      SRV      0      0      88
+kdc1.packetcable.com.
+_kerberos._udp.PACKETCABLE.COM.      86400      IN      SRV      1      0      88
+kdc2.packetcable.com.
+```
+
+To obtain records pertaining to the realm PACKETCABLE.COM, the MTA would send a DNS SRV request for:
+
+```
+kerberos._udp.PACKETCABLE.COM
+```
+
+The client, upon receiving a response for a DNS SRV request, MUST consider the priority/weight as described in the algorithm in RFC 2782 and contact the servers in that order. A client MUST contact the next server based on priority/weight and so on, till all possible server FQDNs and the corresponding IPs are exhausted, if it fails to get a suitable response from the first server listed (refer to 6.4.8 for timeout procedures).
+
+For example, after the above DNS SRV records are retrieved, the client will try kdc1.packetcable.com first, based on its priority. (Priority for kdc1.packetcable.com is 0, while priority for kdc2.packetcable.com is 1: a lower priority number means a higher priority.)
+
+When an IPCablecom KDC is requesting information from a Provisioning Server (e.g., the mapping of an MTA MAC address to its corresponding FQDN) it MUST use a principal name of type NT-PRINCIPAL (1) with a single component "kdcquery" (without quotes).
+
+In an ASCII representation, the principal identifier is as follows:
+
+```
+kdcquery@<realm>
+```
+
+where <realm> is the Kerberos realm of the KDC.
+
+#### 6.4.5.3 CMS
+
+A CMS Kerberos principal identifier MUST be constructed from the CMS FQDN as follows:
+
+```
+cms/<FQDN>@<realm>
+```
+
+where <FQDN> is the CMS's FQDN (in lower case) and <realm> is its Kerberos realm.
+
+For example, a CMS with an FQDN 'iptel-cms1.company1.com' and with a realm name 'COMPANY1.COM' would have the principal identifier:
+
+```
+'cms/iptel-cms1.company1.com@COMPANY1.COM'
+```
+
+The Kerberos PrincipalName data structure (inside the Kerberos messages) is defined as follows:
+
+```
+PrincipalName ::= SEQUENCE {
+    name-type      [0]  INTEGER,
+    name-string  [1]  SEQUENCE OF GeneralString
+}
+```
+
+Within this data structure, name-type MUST be NT-SRV-HST (which has the value of 3 according to the Kerberos specification). The name-string element of the data structure MUST have exactly two components, where the first component has the string value "cms" (without the quotes) and the second component is the CMS's FQDN in lower case.
+
+For the full syntax of Kerberos principal names, refer to IETF RFC 4120.
+
+For the purpose of setting up an IPsec connection between the CMS and RKS, the first component of the CMS principal name MUST be of the form "cms:<ElementID", where the <ElementID> is described in 6.4.5.5.
+
+In the case of a combined network element that integrates the functions of multiple logical elements within the PacketCable reference architecture (e.g., a single network element that provides both CMS and MGC functionality), the principal name may include all server functions as specified in 6.4.5.5.
+
+#### 6.4.5.4 Provisioning Server
+
+When an IPCablecom MTA Provisioning Server is acting in the role of an SNMP manager, it MUST use a principal name of type NT-SRV-HST (3) with the following two components:
+
+- 1) "mtaprovsrvr" (without quotes);
+- 2) the FQDN of the Provisioning Server (in lower case).
+
+In ASCII representation, the Provisioning Server's principal identifier MUST be as follows:
+
+`mtaprovsrvr /<Prov Server FQDN>@<realm>`
+
+where <realm> is the Kerberos realm of the Provisioning Server.
+
+When an IPCablecom Provisioning Server is providing a service (to the KDC) that maps each MTA MAC address to its corresponding FQDN, it MUST use a principal name of type NT-SRV-HST (3) with the following two components:
+
+- 1) "mtafqdnmap" (without quotes);
+- 2) the FQDN of the Provisioning Server (in lower case).
+
+In ASCII representation, the principal identifier MUST be as follows:
+
+`mtafqdnmap/<Prov Server FQDN>@<realm>`
+
+where <realm> is the Kerberos realm of the Provisioning Server.
+
+#### 6.4.5.5 Names of other Kerberized services
+
+All Kerberized services within IPCablecom except for the KDC krbtgt service (see 6.4.5.2), MUST be assigned a service principal name of type KRB\_NT\_SRV\_HST (Value=3), which has the following form according to the Kerberos specification: <service name>/<FQDN>.
+
+This means that the first component of the service principal name is the service name in lower case, and the last is either an FQDN in lower case or an IP address of the corresponding host. If a specific host has an assigned FQDN, its principal name includes an FQDN and not an IP address. When a KDC receives a ticket request for a service on this host with an IP address instead of an FQDN as the second component of the service principal name, the KDC MUST reject such a request.
+
+When a KDC database contains a service with a principal name that has an IP address as the second component, all ticket requests for this service MUST use the same service principal name with the same IP address as the second component. When a KDC receives a ticket request for this service with an FQDN as the second component of the service principal name, the KDC MUST reject such a request. (This scenario could happen if a service principal is defined in the KDC database at the time when the corresponding host does not have an FQDN, and then later an FQDN for this host is defined as well.)
+
+When an IP address is used, it MUST be formatted as follows:
+
+`[A.B.C.D]`
+
+where A, B, C and D are components of an IPv4 address expressed as decimal numbers. The components of an IP address MUST be separated by a period '.' and the IP address MUST be surrounded by square brackets.
+
+The following is an example of a principal name based on an IP address:
+
+`df/[192.35.65.4]`
+
+Figure 3 shows a number of interfaces for which the necessary security is provided by IPsec. In addition to supplying the required key management using IKE with pre-shared keys, some vendors may choose to implement, and operators to deploy, a Kerberized key management scheme for these interfaces.
+
+This Recommendation requires that the RKS verifies billing event messages by ensuring that the Element ID contained in the message matches correctly the IP address at the far end of the IPsec Security Associations. In order to ensure that the RKS is able to maintain this mapping when Kerberized key management is used to generate the Security Associations, devices that communicate with the RKS include their Element ID in their principal name. This information is then passed to the RKS in the cname field of the ticket that the KDC issues; this ticket is passed to the RKS in the AP-REQ that is used to initiate the IPsec Security Associations.
+
+The first component of the principal name for the various IPCablecom devices MUST be as follows:
+
+- 1) BP: bp[:<ElementID>]
+- 2) CMTS: cmts[:<ElementID>]
+- 3) DF: df[:<ElementID>]
+- 4) MG: mg[:<ElementID>]
+- 5) MGC: mgc[:<ElementID>]
+- 6) MP: mp[:<ElementID>]
+- 7) MPC: mpc[:<ElementID>]
+- 8) RKS: rks[:<ElementID>]
+- 9) SG: sg[:<ElementID>]
+
+where:
+
+<ElementID> is the identifier that appears in billing event messages and it MUST be included in a principal name of every server that is capable of generating event messages.
+
+Element ID is defined as an 5-octet right-justified, space-padded ASCII-encoded numerical string (J.164). When converting the Element ID for use in a principal name, any spaces MUST be converted to ASCII zeros (0x48).
+
+For example, a CMTS that has the Element ID "311" will have a principal name whose first component is "cmts:00311". Similarly, a DF with no Element ID will have a principal name whose first component is "df".
+
+Components that contain combined elements (such as a CMS with an integrated MGC) MUST indicate this in the principal name by including all component names, joined with the character "&", in the first component of the principal name. The following is an example of a principal name for a combined CMS and MGC with a single IP address:
+
+`cms:00210&mgc:00211/[192.35.65.4]`
+
+If the combined component uses a single ElementID, the principal name would be:
+
+`cms:00210&mgc:00210/[192.35.65.4]`
+
+### 6.4.6 MTA principal names
+
+An MTA principal name MUST be of type NT-SRV-HST with exactly two components, where the first component MUST be the string "mta" (not including the quotes) and the second component MUST be the FQDN of the MTA: mta /<MTA FQDN>, where <MTA FQDN> is the FQDN of the MTA in lower case.
+
+For example, if an MTA FQDN is "mta12345.mso1.com" and its realm is "MSO1.COM", the principal identifier would be: mta/mta12345.mso1.com@MSO1.COM.
+
+### 6.4.7 Mapping of MTA MAC address to MTA FQDN
+
+The MTA authenticates itself with the MTA Device Certificate in the AS Request, where the certificate contains the MTA MAC address but not its FQDN. In order to authenticate the MTA principal name (containing the FQDN), the KDC MUST map the MTA MAC address (from the MTA Device certificate) to the MTA FQDN, in order to verify the principal name in the AS Request.
+
+The protocol for retrieving the MTA FQDNs is Kerberos-based. The Provisioning Server MUST listen for the request on UDP port 2246 and MUST return the response to the UDP port from which the request was transmitted on the client:
+
+- 1) MTA FQDN Request – sent from the KDC to the Provisioning Server, containing the MTA MAC address and the hash of the MTA public key. This message consists of the Kerberos KRB\_AP\_REQ concatenated with KRB\_SAFE.
+- 2) MTA FQDN Reply – a reply to the KDC by the Provisioning Server, containing the MTA FQDN. This message consists of the Kerberos KRB\_AP REP concatenated with KRB\_SAFE.
+- 3) MTA FQDN Error Reply – an error reply in response to the MTA FQDN Request. This message is the Kerberos KRB\_ERROR.
+
+The format of each of these messages is specified in the clauses below.
+
+#### 6.4.7.1 MTA FQDN Request
+
+The KDC MUST first verify the digital signature and certificate chain in the PKINIT Request, before sending out an MTA FQDN Request message to determine the MTA MAC address to FQDN mapping.
+
+In the case where the PKINIT Request and certificate signatures are all valid but the manufacturer certificate is revoked, the KDC MAY still proceed with the MTA FQDN Request. In this case, the KDC MUST provide the revocation time in the MTA FQDN Request.
+
+The MTA FQDN Request MUST be formatted as in Table 6.
+
+**Table 6 – MTA FQDN Request format**
+
+| Field name | Length   | Description                                     |
+|------------|----------|-------------------------------------------------|
+| KRB_AP_REQ | Variable | DER-encoded. The length is in the ASN.1 header. |
+| KRB_SAFE   | Variable | DER-encoded                                     |
+
+In the KRB\_AP\_REQ, only the following option is supported:
+
+- MUTUAL-REQUIRED – mutual authentication required. This option MUST always be set.
+- All other options are not supported.
+
+The encrypted authenticator in the KRB\_AP\_REQ MUST contain the following field, which is optional in Kerberos:
+
+- seq-number: random value generated by the KDC
+
+All other optional fields within the encrypted authenticator are not supported within IPCablecom. In 6.5.2.2 there is a requirement that the recipient of a KRB\_AP\_REQ accepts certain negative values of seq-number; that requirement does not apply when processing the KRB\_AP\_REQ embedded in a received MTA FQDN message. The authenticator itself MUST be encrypted using
+
+3-DES CBC with the Kerberos etype value des3-cbc-md5 with the session key from the ticket that is contained in this KRB\_AP\_REQ object. The encryption method for des3-cbc-md5 is specified in 6.4.2.2.
+
+KRB\_SAFE MUST contain the following field, which is optional in Kerberos:
+
+- seq-number: same value as in the KRB\_AP\_REQ, to tie KRB\_SAFE to KRB\_AP\_REQ and avoid replay attacks.
+
+All other optional fields within KRB\_SAFE are not supported within IPCablecom. The keyed checksum within KRB\_SAFE MUST be of type rsa-md5-des3 and MUST be computed with the session key in the accompanying KRB\_AP\_REQ. The method for computing an rsa-md5 des3 keyed checksum is specified in 6.4.3.1.
+
+The data that is wrapped inside KRB\_SAFE MUST be formatted as in Table 7:
+
+**Table 7 – KRB\_SAFE format**
+
+| Field name                        | Length   | Description                                                                                                                                   |
+|-----------------------------------|----------|-----------------------------------------------------------------------------------------------------------------------------------------------|
+| Message Type                      | 1 byte   | 1 = MTA FQDN Request                                                                                                                          |
+| Enterprise Number                 | 4 bytes  | Network byte order, MSB first.<br>1 = IPCablecom                                                                                              |
+| Protocol Version                  | 1 byte   | 2 for this version                                                                                                                            |
+| MTA MAC Address                   | 6 bytes  | MTA MAC Address                                                                                                                               |
+| MTA Pub Key Hash                  | 20 bytes | SHA-1 hash of DER-encoded SubjectPublicKeyInfo.                                                                                               |
+| Manufacturer Cert Revocation Time | 4 bytes  | 0 = MTA Manufacturer cert not revoked<br>Otherwise, this is UTC time, number of seconds since midnight of Jan 1, 1970, in network byte order. |
+
+Once the KDC has sent an MTA FQDN Request, it MUST save the nonce value that was contained in the seq-number field in order to validate a matching MTA FQDN Reply.
+
+If the KDC times out before getting a reply it MUST give up and simply drop the PKINIT request with no error code returned. The KDC MUST NOT retry in this case, since it would still have to handle retries of PKINIT Request from the MTA. At the same time, after a time out the KDC SHOULD increase its time out value on the next request to the same Provisioning Server using an exponential back-off algorithm.
+
+The Provisioning Server receiving this message MUST validate the KRB\_AP\_REQ and verify that it is not a replay using the procedure specified in the Kerberos standard (see IETF RFC 4120), also described in 6.5.2. After the KRB\_AP\_REQ has been validated, the Provisioning Server MUST also verify the KRB\_SAFE component: that the checksum keyed with the session key is valid and that the seq-number field matches the KRB\_AP\_REQ.
+
+If the Manufacturer Cert Revocation Time field is 0 and the Provisioning Server supports the storage of MTA public key hashes, then it MUST update the MTA public key hash in its database. If the public key hash has changed or is saved for the first time, the Provisioning Server MUST also record the time this update (to the MTA public key hash) is performed.
+
+- If the Manufacturer Cert Revocation Time field is non-zero, the Provisioning Server MUST validate that the public key hash has not changed from the previous update and that the revocation time is after the last update to the MTA public key hash. If not, the error code KRB\_MTAMA\_ERR\_PUBKE\_NOT\_TRUSTED MUST be returned. If the Provisioning Server does not support storage of MTA public key hashes and the Manufacturer Cert Revocation Time field is non-zero, the same error code MUST be returned.
+
+#### 6.4.7.2 MTA FQDN reply
+
+The MTA FQDN Reply MUST be formatted as in Table 8:
+
+**Table 8 – MTA FQDN format**
+
+| Field name | Length   | Description                                     |
+|------------|----------|-------------------------------------------------|
+| KRB_AP_REP | Variable | DER-encoded. The length is in the ASN.1 header. |
+| KRB_SAFE   | Variable | DER-encoded                                     |
+
+The encrypted part of the KRB\_AP\_REP MUST contain the following field, which is optional in Kerberos:
+
+- seq-number: echoes the value in the KRB\_AP\_REQ
+
+All other optional fields within the encrypted part of the KRB\_AP\_REP are not supported within IPCablecom. It MUST be encrypted using 3-DES CBC with the Kerberos etype value des3-cbc-md5 and MUST be computed with the session key from the preceding KRB\_AP\_REQ. The encryption method for des3-cbc-md5 is specified in 6.4.2.2.
+
+KRB\_SAFE MUST contain the following field, which is optional in Kerberos:
+
+- seq-number: same value as in the KRB\_AP\_REP, to tie KRB\_SAFE to KRB\_AP\_REP and avoid replay attacks.
+
+All other optional fields within KRB\_SAFE are not supported within IPCablecom. The keyed checksum within KRB\_SAFE MUST be of type rsa-md5-des3 and MUST be computed with the session key from the preceding KRB\_AP\_REQ. The method for computing an rsa-md5-des3 keyed checksum is specified in 6.4.3.1.
+
+The data that is wrapped inside KRB\_SAFE MUST be formatted as in Table 9:
+
+**Table 9 – KRB\_SAFE data format**
+
+| Field name        | Length   | Description                                     |
+|-------------------|----------|-------------------------------------------------|
+| Message Type      | 1 byte   | 2 = MTA FQDN Reply                              |
+| Enterprise Number | 4 bytes  | Network byte order, MSB first<br>1 = IPCablecom |
+| Protocol Version  | 1 byte   | 2 for this version                              |
+| MTA FQDN          | variable | MTA FQDN                                        |
+| MTA IP Address    | 4 bytes  | MTA-IP Address (MSB first)                      |
+
+After the KDC receives this reply message, it MUST validate the integrity of both the KRB\_AP\_REP and KRB\_SAFE objects (see IETF RFC 4120) and MUST also verify that the value of the seq-number field is the same for both. If this integrity check fails, the KDC MUST immediately discard the reply and proceed as if the message had never been received (e.g., if the KDC was waiting for a valid MTA FQDN Reply, it should continue to do so).
+
+The Provisioning Server MAY set the MTA IP Address field of the MTA FQDN Reply to zero. If the KDC receives an MTA FQDN REPLY with a non-zero MTA IP Address field, it MUST compare it to the IP address contained in the AS Request. If this check fails, then the KDC MUST NOT respond to the AS Request.
+
+#### 6.4.7.3 MTA FQDN error
+
+If the Provisioning Server is able to successfully parse the KRB\_AP\_REQ and the ticket that is inside of it, but the MTA FQDN Request is rejected, it MUST return an error message.
+
+All errors MUST be returned as a KRB\_ERROR message, as specified in IETF RFC 4120. It MUST include typed-data of REQ-SEQ to bind the error message to the sequence number from the authenticator in the KRB\_AP\_REQ. Also, the error message MUST include the optional e-cksum member, which is the keyed hash over the KRB\_ERROR message. The checksum type MUST be rsa-md5-des3 and MUST be computed with the session key from the preceding KRB\_AP\_REQ as specified in 6.4.3.1.
+
+In the case that the client time field inside KRB\_AP\_REQ differs from the Provisioning Server's clock by more than the maximum allowable clock skew, a clock skew error MUST be handled as specified in 6.5.2.3.2.
+
+If the error is application-specific (not a Kerberos-related error), then KRB\_ERROR MUST include typed-data of type TD-APP-DEFINED-ERROR (value 106). The value of this typed-data is specified in IETF RFC 4120 as follows:
+
+```
+AppSpecificTypedData ::= SEQUENCE {  
+    oid           [0] OPTIONAL OBJECT IDENTIFIER,  
+                        -- identifies the application  
+    data-value    [1] OCTET STRING  
+                        -- application-specific data  
+}
+```
+
+Inside AppSpecificTypedData, the oid field MUST be set to:
+
+```
+enterprises (1.3.6.1.4.1) cableLabs (4491) clabProjects (2) clabProjPacketCable  
+(2) pktcSecurity (4) errorCodes (1) FQDN (3)
+```
+
+The data-value field MUST correspond to the following typed-data value:
+
+```
+pktcKrbMtaMappingError ::= SEQUENCE {  
+    e-code[0] INTEGER,  
+    e-text[1] GeneralString OPTIONAL,  
+    e-data[2] OCTET STRING OPTIONAL  
+}
+```
+
+The e-code field MUST correspond to one of the following error code values:
+
+|                                   |   |                                   |
+|-----------------------------------|---|-----------------------------------|
+| KRB_MTAMAP_ERR_NOT_FOUND          | 1 | MTA MAC Address not found         |
+| KRB_MTAMAP_ERR_PUBKEY_NOT_TRUSTED | 2 | MTA public key is not trusted     |
+| KRB_MTAMAP_VERSION_UNSUP          | 3 | Unsupported Version Number        |
+| KRB_MTAMAP_MSGTYPE_UNKNOWN        | 4 | Unrecognized Message Type         |
+| KRB_MTAMAP_ENTERPRISE_UNKNOWN     | 5 | Unrecognized Enterprise<br>Number |
+| KRB_MTAMAP_NOT_YET_VALID          | 6 | MTA not yet valid                 |
+| KRB_MTAMAP_ERR_GENERIC            | 7 | Generic MTA name<br>mapping error |
+
+The optional e-text field can be used for informational purposes (i.e., logging, network troubleshooting) and the optional e-data field is reserved for future use to transport any application data associated with a specific error.
+
+Upon receipt of a KRB\_ERROR from the Provisioning Server, the KDC MUST check the validity of the checksum. If the KRB\_ERROR passes the validity check, the KDC MUST send a corresponding KRB\_ERROR to the MTA (as specified in 6.4.2.1.2), in response to the PKINIT Request. The application specific MAC-FQDN error codes MUST be mapped to Kerberos error codes in the error reply to the MTA according to Table 10.
+
+**Table 10 – Mapping of KRB\_MTAMAP\_ERR to KRB\_ERR**
+
+|                                   |                             |
+|-----------------------------------|-----------------------------|
+| KRB_MTAMAP_ERR_NOT_FOUND          | KDC_ERR_C_PRINCIPAL_UNKNOWN |
+| KRB_MTAMAP_ERR_PUBKEY_NOT_TRUSTED | KDC_ERR_CLIENT_REVOKED      |
+| KRB_MTAMAP_VERSION_UNSUP          | KRB_ERR_GENERIC             |
+| KRB_MTAMAP_MSGTYPE_UNKNOWN        | KRB_ERR_GENERIC             |
+| KRB_MTAMAP_ENTERPRISE_UNKNOWN     | KRB_ERR_GENERIC             |
+| KRB_MTAMAP_NOT_YET_VALID          | KDC_ERR_CLIENT_NOTYET       |
+| KRB_MTAMAP_ERR_GENERIC            | KRB_ERR_GENERIC             |
+
+### **6.4.8 Server key management time-out procedure**
+
+The Kerberos client MUST implement a retransmission strategy using exponential back-off with configurable initial and maximum retransmission timer values for any KDC or application server requests that have not been acknowledged by the server. The Kerberos client MUST update the client timestamp field with the current time-of-day reading for each such retry. During an exponential back-off, when a previous time out value was  $T_i$ , then the next time out value, value  $T_{i+1}$ , MUST satisfy the following criteria:
+
+$$1.5 \times T_i \leq T_{i+1} \leq 2.5 \times T_i$$
+
+After successfully processing an AS Request or TGS Request and generating a corresponding reply, the KDC MUST save:
+
+- the AS Request or TGS Request (e.g., the full AS Request/TGS Request or a hash of the AS Request/TGS Request);
+- the full KDC reply.
+
+The KDC MUST maintain this information for all requests with the client time field that is within the time window  $(T - \Delta T_{MAX}, T + \Delta T_{MAX})$ , where  $T$  is the current time and  $\Delta T_{MAX}$  is the maximum clock skew that is allowed by the KDC policy.
+
+The KDC MAY also save:
+
+- the client principal identifier;
+- the information that uniquely identifies the client pre-authentication field in the AS Request (PKINIT or encrypted timestamp in the case of non-public key AS Request) or TGS Request (PA-TGS-REQ).
+
+The KDC MAY maintain this information for all requests with the client time field that is within the time window  $(T - \Delta T_{MAX}, T + \Delta T_{MAX})$ , where  $T$  is the current time and  $\Delta T_{MAX}$  is the maximum clock skew that is allowed by the KDC policy. If the AS Request or TGS Request is identical to the one previously received, the KDC MUST respond with the same reply message. If only the principal name and pre-authenticator (PKINIT, encrypted timestamp or PA-TGS-REQ) match, then the KDC MUST perform one of the following:
+
+- If the received AS Request or TGS Request passes all other error checks, the KDC may reply with a cached reply message.
+- Reject this message as a replay.
+
+The MTA may have learned several IP addresses for a KDC or application server (refer to 6.4.5.2 for more information on obtaining IP addresses from Realm Names and forming a local list of IP addresses based on prioritization). If the number of retransmissions for a KDC IP address has reached its maximum configured value and there are more IP addresses for the same KDC that have not been tried, then the MTA MUST direct the retransmissions to the remaining alternate addresses in its local list. Each time that the MTA switches to a new KDC IP address for retransmissions, it MUST start a new exponential back-off procedure. If there are no more KDC IP addresses to try,
+
+then the MTA SHOULD actively query the name server in order to detect the possible change of KDC network interfaces, regardless of the Time To Live (TTL) associated with the DNS record to see if any other IP addresses have become available. If there are new IP Addresses discovered, the MTA MUST go through the retransmission strategy again for the newly discovered IP Addresses.
+
+For Kerberized key management with application servers, when an application layer is informed that key management with a particular IP address failed, it is normally up to the application layer to select the next IP address. The switch-over algorithm between multiple IP addresses mapped to the same FQDN is specified by each corresponding application protocol. For example, in the case of the Kerberized key management between the MTA and the CMS, refer to the NCS specification (ITU-T Rec. J.162). There are also cases when key management is performed independent of the application layer, e.g., to pre-establish security associations during MTA initialization. In those cases, it is up to a specific MTA implementation to decide if to failover and how to failover to another application server IP address.
+
+An application server may not respond to application messages (e.g., NCS messages) from the MTA. This may occur if the MTA has valid security parameters with the application server, but the security parameters on the server have been lost or corrupted (e.g., the CMS rebooted and lost all IPsec Security Associations).
+
+In the case of NCS signalling, an MTA MUST no longer use any previously established IPsec SAs with a particular CMS each time the NCS back-off and retry algorithm places an MTA endpoint controlled by that CMS into a DISCONNECTED state. After an MTA endpoint has moved to a DISCONNECT state, it will start sending RSIP/disconnect NCS messages which will need to be protected by newly established IPsec SAs.
+
+### 6.4.9 Service key versioning
+
+The service key that is shared between a KDC and an application server, to encrypt/decrypt service tickets, is a versioned key (refer to IETF RFC 4120). This key may be changed either due to a routine key refresh, or because it was compromised. When the service key is changed, the application server MUST retain the older key for a period of time that is at least as long as the ticket lifetime used when issuing service tickets (i.e., up to 7 days). In the case of a routine service key change, the application server MUST accept any ticket that is encrypted with an older key that it has retained and is still valid (not compromised). This key versioning on the application server will prevent against many MTAs from suddenly flooding a KDC with PKINIT Requests for new tickets.
+
+If a service key is changed because it has been compromised, the application server MUST flag all older key versions it has retained as invalid and reject any AP Request that contains a ticket that is encrypted with one of these invalid keys. When rejecting the AP Request, the application server MUST respond as specified in IETF RFC 4120 with a KRB\_AP\_ERR\_BADKEYVER error. The application server MUST still decrypt the rejected ticket, using the invalid service key, in order to extract the session key. This session key is needed to securely bind the KRB\_ERROR reply message to the AP Request message using a keyed checksum (see 6.5.2.3.1). Note that this step is necessary in order to prevent denial-of-service attacks, which could otherwise occur if the MTA was unable to verify the authenticity of the KRB\_ERROR message.
+
+Upon receiving this error reply, the MTA MUST discard the service ticket which is no longer valid and fetch a new one from its KDC.
+
+## 6.5 Kerberized key management
+
+### 6.5.1 Overview
+
+This clause specifies how Kerberos tickets are used to perform key management between a client and an Application Server, where a client is able to get a Kerberos ticket for the server but not the other way around.
+
+The same protocol described here applies in a symmetric case – where both sides of a key management interface are able to get a ticket for each other, i.e., each side is both a client and a server. In the symmetric case, only the AP Request and AP Reply messages apply.
+
+The Kerberos session key is used in the AP Request and AP Reply messages that are exchanged in order to re-establish security parameters. The sub-key from the AP-REQ and AP-REP are used to derive all of the secret keys used for both directions. The AP Request and AP Reply messages are small enough to fit into a standard UDP packet, not requiring fragmentation.
+
+A Kerberos AP Request/Reply exchange MAY occur periodically, to ensure that there are always valid security parameters between the client and the Application Server. It MAY also occur on demand, where the security parameters are allowed to time out and are re-established the next time that application traffic needs to be sent over a secure link.
+
+The UDP port used for all key management messages between the client and the Application Server MUST be 1293 (on both devices).
+
+A recipient of any Kerberized Key Management message that does not fully comply with the IPCablecom requirements MUST reject the message.
+
+### 6.5.2 Kerberized key management messages
+
+Figure 8 illustrates an AP Request/AP Reply exchange:
+
+![Sequence diagram of Kerberos AP Request/AP Reply exchange between MTA and Application Server.](107c8e1abcb7033ad244e30e7a910045_img.jpg)
+
+The diagram illustrates the interaction between an MTA and an Application Server for Kerberos AP Request/AP Reply exchange. The sequence of messages is as follows:
+
+- 1) Wake Up<sup>a)</sup>:** The Application Server sends a message to the MTA containing a Server-nonce and the Application Server Kerberos Principal Identifier. The MTA has a { Ticket, Session Key } and the Application Server has a { Service Key }.
+- 2) AP Request:** The MTA sends a message to the Application Server containing a Service Ticket, MTA name + time + hash (encrypted with session key), Server-nonce, Application-specific data (e.g., SPI for IPsec), a list of available ciphersuites, a Re-establish flag, and a SHA-1 HMAC.
+- 3) AP Reply:** The Application Server sends a message to the MTA containing time + subkey (encrypted with session key), Application-specific data (e.g., SPI for IPsec), selected ciphersuite, SA lifetime, Grace period, Re-establish flag, ACK required flag, and a SHA-1 HMAC. The MTA has { subkey → security parameters } and the Application Server has { subkey → security parameters }.
+- 4) Security Parameter Recovered<sup>b)</sup>:** The MTA sends a message to the Application Server.
+
+Following the exchange, a **secure session** is established between the MTA and the Application Server. The diagram is labeled J.170\_F08.
+
+Sequence diagram of Kerberos AP Request/AP Reply exchange between MTA and Application Server.
+
+- a) This message is sent whenever key management is initiated by an Application Server.
+- b) This message is optional, sent whenever the ACK-required flag is set in the preceding AP Reply.
+
+**Figure 8 – Kerberos AP Request/AP Reply exchange**
+
+- 1) Wake Up – An Application Server sends this message when it initiates a new key management exchange.
+
+To prevent denial-of-service attacks, this message includes a Server-nonce field – a random value generated by the Application Server. The client includes the exact value of this Server-nonce in the subsequent AP Request.
+
+This message also contains the Server Kerberos principal identifier, used by the client to find or to obtain a correct Kerberos ticket for that Application Server.
+
+The Wake Up message MUST be formatted as the concatenation of the following fields:
+
+- Key Management Message ID – 1-byte value. Always set to 0x01.
+- Domain of Interpretation (DOI) – 1-byte value. Specifies the target protocol for which security parameters are established.
+
+| <b>Domain of Interpretation (DOI) values</b> |                        |
+|----------------------------------------------|------------------------|
+| <b>Value</b>                                 | <b>Target protocol</b> |
+| 1                                            | IPsec                  |
+| 2                                            | SNMPv3                 |
+
+- Protocol Version – 1 byte. The high-order nibble is the major version number, and the lower-order nibble is the minor version number. For IPCablecom, the major number MUST be 1, and the minor number MUST be 0.
+- Server-nonce: a 4-byte random binary string. Its value MUST NOT be all 0s.
+- Server Kerberos principal identifier: a printable, null-terminated ASCII string, representing a fully qualified Kerberos Principal identifier of the Application Server, as defined in 6.4.5.
+
+Once the Application Server has sent a Wake Up, it MUST save the Server-nonce. The Application Server MUST keep this nonce in order to validate a matching AP Request. In the case of a time-out, the Application Server MUST adhere to the exponential retry back-off procedure described in 6.4.8. The Application Server MUST begin each retry by re-sending a Wake Up message with a new server-nonce value. When the "Timeout Procedure" has completed without success, the Application Server MUST discard the server-nonce from the last retry, after which it will no longer accept a matching AP Request.
+
+- 2) AP Request – MUST be sent by the client in order to establish a new set of security parameters. Any time the client receives a Wake Up message from a valid application server that is listed as part of client configuration data, it MUST respond with the AP Request message specified below. If a client receives a Wake Up message from an unknown application server, the client MUST NOT respond.
+
+In addition, this Recommendation specifies the use of this message by the client to periodically establish a new set of security parameters with the Application Server – see 6.5.4.2. It also specifies the use of this message by the client to establish a new set of security parameters with the Application Server, when the client somehow loses the security parameters (e.g., after a reboot) – see 6.5.3.5.
+
+The client starts out with a valid Kerberos ticket, previously obtained during a PKINIT exchange. The Application Server starts out with its Service Key that it can use to decrypt and validate Kerberos tickets.
+
+The client sends an AP Request that includes a ticket and an authenticator, encrypted with the session key. The Application Server gets the session key out of the ticket and uses it to decrypt and then validate the authenticator.
+
+The AP Request includes the Kerberos KRB\_AP\_REQ message along with some additional information, specific to IPCablecom. It MUST consist of the concatenation of the following fields:
+
+- Key Management Message ID – 1-byte value. Always set to 0x02.
+- Domain of Interpretation (DOI) – 1-byte value. Specifies the target protocol for which security parameters are established. See the table of DOI values above.
+
+- Protocol Version – 1 byte. The high-order nibble is the major version number, and the lower-order nibble is the minor version number. For IPCablecom, the major number MUST be 1, and the minor number MUST be 0.
+- KRB\_AP\_REQ – DER encoding of the KRB\_AP\_REQ Kerberos message, as specified in IETF RFC 4120.
+- Server-nonce – a 4-byte random binary string. If this AP Request is in response to a Wake Up, then the value MUST be identical to that of the Server-nonce field in the Wake Up message. If this AP Request is in response to a Rekey (see 6.5.2.1), then the value MUST be identical to that of the Server-nonce field in the Rekey message. Otherwise, the value MUST be all 0s.
+- Application-specific data – additional information that must be communicated by the client to the server, dependent on the target protocol for which security is being established (e.g., IPsec or SNMPv3).
+- List of ciphersuites available at the client:  
+ Number of entries in this list (1 byte)  
+ Each entry has the following format:
+
+|                                          |                                         |
+|------------------------------------------|-----------------------------------------|
+| <b>Authentication Algorithm (1 byte)</b> | <b>Encryption Transform ID (1 byte)</b> |
+|------------------------------------------|-----------------------------------------|
+
+The actual values of the authentication algorithms and encryption transform IDs are dependent on the target protocol.
+
+- Re-establish flag – a 1-byte Boolean value. When the value is TRUE (1), the client is making an attempt to automatically establish a new set of Security Parameters before the old one expires. Otherwise, the value is FALSE (0).
+- SHA-1 HMAC (20 bytes) over the contents of this message, not including this field. The 20-byte key for this HMAC is determined by taking a SHA-1 hash of the session key.
+- Whenever the AP Request is received (by the Application Server), it MUST verify the value of this HMAC. If this integrity check fails, the Application Server MUST immediately discard the AP Request and proceed as if the message had never been received (e.g., if the Application Server was waiting for a valid AP Request, it should continue to do so).
+
+Once the client has sent an AP Request, it MUST save the nonce value that was contained in the seq-number field (a different nonce from the server-nonce specified above) along with the server Kerberos principal identifier in order to validate a matching AP Reply. If the client generated this AP Request on its own, it MUST adhere to the exponential retry backoff procedure described in 6.4.8.
+
+If the AP Request was generated in response to a message sent by the Application Server (Wake Up or Rekey), then the client MUST save the nonce and Server Kerberos Principal Identifier until the time specified by the appropriate Key Management MIB variables (pktcMtaDevProvSolicitedKeyTimeout for Prov Server, pktcMtaDevCmsSolicitedKeyTimeout for CMS). After the timeout has been exceeded or when the "Timeout Procedure" has completed without success, the client MUST discard this (nonce, server Kerberos principal identifier) pair, after which it will no longer accept a matching AP Reply.
+
+If the MTA generated an AP Request on its own and has reached the maximum number of retries with a particular application server IP address failing to get an AP Reply, it must retry with alternate application server IP addresses as specified in 6.4.8.
+
+In the case that the Server-nonce is 0 (not filled in), and the Application Server is currently waiting for a reply to a Wake Up or Rekey message from a client at this IP address, it MUST reject the AP Request and not reply to the client. If the Application Server is not waiting for a reply to a Wake Up or Rekey message, it MUST verify that this AP Request is not a replay using the procedure specified in the Kerberos standard (IETF RFC 4120):
+
+- If the timestamp in the AP Request differs from the current Application Server time by more than the acceptable clock skew then the Application Server MUST reply with an error message specified in 6.5.2.3.2.
+- If the realm, Application Server name, along with the client name, time and microsecond fields from the Kerberos Authenticator (in the AP Request) match any recently-seen such tuples, the KRB\_AP\_ERR\_REPEAT error MAY be returned.
+
+The Application Server MUST remember any authenticator presented within acceptable clock skew, so that a replay attempt is guaranteed to fail.
+
+- If the Application Server loses track of any authenticator presented within pktcSrvrToMtaMaxClockSkew, it MUST reject all requests until the clock skew interval has passed.
+
+In the case that the Server-nonce is not 0, the Application Server MAY follow the above procedure in order to fully conform with the Kerberos specification (IETF RFC 4120). In this case, the above procedure is not required because matching the Server-nonce in the Wake Up or Rekey message against the Server-nonce in the AP Request also prevents replays.
+
+#### 3) AP Reply – Sent by the Application Server in response to AP Request.
+
+The AP Reply MUST include a randomly generated sub-key (inside the Kerberos KRB\_AP\_REP message), encrypted with the same session key.
+
+The AP Reply includes the Kerberos KRB\_AP\_REP message along with some additional information, specific to IPCablecom. It MUST consist of the concatenation of the following fields:
+
+- Key Management Message ID – 1-byte value. Always set to 0x03.
+- Domain of Interpretation (DOI) – 1-byte value. Specifies the target protocol for which security parameters are established. See the table of DOI values in this clause.
+- Protocol Version – 1 byte. The high-order nibble is the major version number, and the lower-order nibble is the minor version number. For IPCablecom, the major number MUST be 1, and the minor number MUST be 0.
+- KRB\_AP\_REP – DER encoding of the KRB\_AP\_REP Kerberos message, as specified in IETF RFC 4120.
+- Application-specific data – additional information that must be communicated by the server to the client, dependent on the target protocol for which security is being established (e.g., IPsec or SNMPv3).
+- Selected ciphersuite for the target protocol, using the same format as defined for AP Request. The number of entries in the list MUST be one.
+- Security parameters lifetime – a 4-byte value, MSB first, indicating the number of seconds from now, when these security parameters are due to expire.
+- Grace period – a 4-byte value in seconds, MSB first. This indicates to the client to start creating a new set of security parameters (with a new AP Request/AP Reply exchange) when the timer gets to within this period of their expiration time.
+
+- Re-establish flag – a 1-byte Boolean value. When the value is TRUE (1), a new set of security parameters MUST be established before the old one expires. When the value is FALSE (0), the old set of security parameters MUST be allowed to expire.
+- ACK-required flag – a 1-byte Boolean value. When the value is TRUE (1), the AP Reply message requires an acknowledgement, in the form of the Security Parameter Recovered message.
+- SHA-1 HMAC (20 bytes) over the contents of this message, not including this field. The 20-byte key for this HMAC is determined by taking a SHA-1 hash of the session key.
+
+Whenever the AP Reply is received (by the client), it MUST:
+
+- verify the value of this HMAC. If this integrity check fails, the client MUST immediately discard the AP Reply;
+- verify that the AP Reply Source IP Address matches the AP Request Destination IP Address in the list of outstanding AP Requests. The Client MUST immediately discard the AP Reply, which cannot be matched for the corresponding AP Request;
+- verify that the nonce value contained in the seq-number field in AP Reply matches the one in the corresponding AP Request. The Client MUST immediately discard the AP Reply if seq-number field value in AP Reply does not match.
+
+If the AP Reply is discarded, the Client MUST proceed as if the message had never been received (e.g., if the client was waiting for a valid AP Reply, it should continue to do so). Once the Application Server has sent an AP Reply with the ACK-required flag set, it MUST compute the expected value in the Security Parameter Recovered message and save it for an appropriate timeout period during which it will accept a matching Security Parameter Recovered Message. Once the appropriate timeout period is exceeded, the Application Server MUST discard the saved values and no longer accept a matching Security Parameter Recovered Message
+
+Each time the Application Server times out waiting for the Security Parameter Recovered message, it MUST continue with the exponential back-off algorithm until all retries have been exhausted, as specified in clause 6.4.8. The Application Server MUST begin each retry by re-sending a Wake Up message with a new server-nonce value.
+
+- 4) Security Parameter Recovered – Sent by the client to the Application Server to acknowledge that it received an AP Reply and successfully set up new Security Parameters. This message is only sent when ACK-required flag is set in the AP Reply.
+
+This message MUST consist of the concatenation of the following:
+
+- Key Management Message ID – 1-byte value. Always set to 0x04.
+- Domain of Interpretation (DOI) – 1-byte value. Specifies the target protocol for which security parameters are established. See the table of DOI values in this clause.
+- Protocol Version – 1 byte. The high-order nibble is the major version number, and the lower-order nibble is the minor version number. For IPCablecom, the major number MUST be 1, and the minor number MUST be 0.
+- HMAC – a 20-byte SHA-1 HMAC of the preceding AP Reply message. The 20-byte key for this HMAC is determined by taking a SHA-1 hash of the sub-key from the AP Reply.
+
+If the receiver (Application Server) gets a bad Security Parameter Recovered message that does not match an AP Reply, the Application Server MUST discard it and proceed as if this Security Parameter Recovered message was never received.
+
+#### 6.5.2.1 Rekey messages
+
+The Rekey message replaces the Wake Up message and provides better performance, whenever a receiver (Application Server) wants to trigger the establishment of a Security Parameter with a specified client. The Rekey message requires the availability of the shared Server Authentication Key, which is not always available. Thus, support for the Wake Up message is still required.
+
+The Rekey message was added specifically for use with the NCS-based clustered Call Agents, potentially consisting of multiple IP addresses and multiple hosts. Any IP address or host within one cluster needs the ability to quickly establish a new Security Parameter with a client, without a significant impact to the ongoing voice communication.
+
+The use of the Rekey message eliminates the need for the AP Reply message, thus reducing the key management overhead to a single round trip. This is illustrated in Figure 9.
+
+![Sequence diagram showing the Rekey message exchange between MTA and CMS to establish a security parameter. The diagram includes two main messages: (1) Rekey and (2) AP Request. It also shows the initial key sets and the resulting IPSEC ESP keys.](343e05a9fd8a8c8743428fa4ae6e2736_img.jpg)
+
+The diagram illustrates the interaction between an MTA (left) and a CMS (right) to establish a security parameter. At the top, two key sets are shown in curly braces:   
+ Left: { Ticket, Session Key, Server Auth Key }   
+ Right: { Service Key, Server Auth Key }
+
+(1) Rekey:   
+ A message from CMS to MTA containing:   
+ - CMS nonce   
+ - CMS Kerberos Principal Identifier   
+ - timestamp   
+ - IPsec parameters:   
+   list of available ciphersuites   
+   SA lifetime   
+   IPsec grace period   
+   Re-establish flag   
+ - SHA-1 HMAC
+
+(2) AP Request:   
+ A message from MTA to CMS containing:   
+ - CMS ticket,   
+ - MTA name + time + subkey + hash   
+   encrypted with the session key   
+ - CMS nonce   
+ - IPsec parameters:   
+   ASD   
+   selected ciphersuite   
+ - SHA-1 HMAC
+
+At the bottom, two key derivation sets are shown in curly braces:   
+ Left: { sub-key → IPSEC ESP Keys }   
+ Right: { sub-key → IPSEC ESP Keys }
+
+A double-headed arrow at the bottom is labeled "IPSEC ESP". The diagram is signed "J.170\_F09" in the bottom right corner.
+
+Sequence diagram showing the Rekey message exchange between MTA and CMS to establish a security parameter. The diagram includes two main messages: (1) Rekey and (2) AP Request. It also shows the initial key sets and the resulting IPSEC ESP keys.
+
+**Figure 9 – Rekey message to establish a security parameter**
+
+The messages listed in Figure 9 are defined as follows:
+
+- 1) Rekey – Sent by the Application Server to establish a new set of security parameters. It MUST be a concatenation of the following:
+  - Key Management Message ID – 1-byte value. Always set to 0x05.
+  - Domain of Interpretation (DOI) – 1-byte value. Specifies the target protocol for which security parameters are established. See the table of DOI values in this clause.
+
+- Protocol Version – 1 byte. The high-order nibble is the major version number, and the lower-order nibble is the minor version number. For IPCablecom, the major number MUST be 1, and the minor number MUST be 0.
+- Server-nonce – a 4-byte random binary string. Its value MUST NOT be all 0s.
+- Server Kerberos principal identifier – a printable, null-terminated ASCII string, representing a fully qualified Kerberos principal identifier of the Application Server, as defined in 6.4.5. This allows the client to both find the right Server Authentication Key and to pick the right Kerberos ticket for the subsequent AP Request message.
+- Timestamp – a string of the format YYMMDDhhmmssZ, representing UTC time. This string is not NULL-terminated.
+- Application-specific data – additional information that must be communicated by the server to the client, dependent on the target protocol for which security is being established (e.g., IPsec).
+- List of ciphersuites available at the server – see above specification for the AP Request message.
+- Security parameters lifetime – a 4-byte value, MSB first. This indicates the number of seconds from now, when this set of security parameters is due to expire.
+- Grace period – a 4-byte value in seconds, MSB first. This indicates to the client to start creating a new set of security parameters (with a new AP Request/AP Reply exchange) when the timer gets to within this period of their expiration time.
+- Re-establish flag – a 1-byte Boolean value. When the value is TRUE (1), a new set of security parameters MUST be established before the old one expires. When the value is FALSE (0), the old set of security parameters MUST be allowed to expire.
+- SHA-1 HMAC over the concatenation of all of the above-listed fields.
+
+The Server Authentication Key used for this HMAC is uniquely identified by the following name pair (client principal name, server principal name). This key MUST be updated at the Application Server right after it sends an AP Reply message. It MUST be set to a (20-byte) SHA-1 hash of the Kerberos session key used in that AP Reply. The client MUST also update this key as soon as it receives the AP Reply. (Note that multiple AP Replies will continue using the same Kerberos session key, until it expires. That means that the derived Server Authentication Key may have the same value as the old one.)
+
+It is possible that the Application Server sends a Rekey message as soon as it sends an AP Reply (from another IP address), and before the client is able to derive the new Server Authentication Key. In that case, the client will not authenticate the Rekey message and the Application Server will have to retry.
+
+Similarly, after sending an AP Reply the Application Server might immediately send an IP packet using the just established Security Parameter, when the client is not yet ready to receive it. In this case, the client will reject the packet and the Application Server will have to retransmit.
+
+Both of these error cases could be completely avoided with a 3-way handshake (a client acknowledging an AP Reply with a Security Association Recovered message).
+
+Whenever the Rekey message is received (by the client), it MUST verify the value of this HMAC. If this integrity check fails, the client MUST immediately discard this message and proceed as if the message had never been received.
+
+Once the Application Server has sent a Rekey, it MUST save the server-nonce in order to validate a matching AP Request. In the case of a time-out, the Application Server MUST adhere to the exponential retry backoff procedure described in 6.4.8. The Application Server MUST begin each retry by re-sending a Rekey message with a new server-nonce
+
+value. When the "Time-out Procedure" has completed without success, the Application Server MUST discard the server-nonce from the last retry, after which it will no longer accept a matching AP Request.
+
+When this Rekey message is received and validated by the client, all previously existing outgoing Security Parameters with this Application Server IP address MUST be removed at this time. If the client previously had a timer set for automatic refresh of Security Parameters with this Application Server IP address, that automatic refresh MUST be reset or disabled.
+
+The client MUST verify that this Rekey message is not a replay using the procedure similar to the one for AP Request in the Kerberos standard (IETF RFC 4120):
+
+- If  $|T_{CMS} - (T_{MTA} + \text{Skew})| > \text{The acceptable Clock Skew}$ , then the client MUST drop the message. Here,  $T_{CMS}$  is the timestamp in the Rekey message and  $T_{MTA}$  is the reading of the MTA local clock. Skew is the saved difference between the Application Server and MTA clock. PktcSrvrToMtaMaxClockSkew is currently in the MTA MIB (see ITU-T Rec. J.166) as the variable pktcMtaDevCmsMaxClockSkew.
+- If the Server-nonce, principal name and timestamp fields match any recently seen (within the pktcSrvrToMtaMaxClockSkew) Rekey messages, then the client MUST drop the message.
+
+- 2) AP Request – MUST be sent by the client as a response to a Rekey message. Unlike the AP Request message described above, this one MUST also include the sub-key (inside KRB\_AP\_REQ ASN.1 structure). KRB\_AP\_REQ will have a Kerberos flag set, indicating that an AP Reply MUST NOT follow.
+
+The format of the AP Request is as specified above in 6.5.2. The only difference is that the list of ciphersuites here MUST contain exactly one entry – the ciphersuite selected by the client from the list provided in the Rekey message.
+
+Right before the client sends out this AP Request, it MUST establish the security parameters with the corresponding server IP address. If the corresponding Rekey message had the Re-establish flag set, the client MUST be prepared to automatically re-establish new security parameters, as specified in 6.5.
+
+Once this AP Request is received and verified by the Application Server, the server MUST also establish the security parameters.
+
+#### 6.5.2.2 IPCablecom profile for KRB\_AP\_REQ/KRB\_AP\_REP messages
+
+In the KRB\_AP\_REQ, only the following option is supported:
+
+- MUTUAL-REQUIRED – mutual authentication required. When this option is set, the server MUST respond with an AP Reply message. When this option is not set, the AP Reply message MUST NOT be sent in reply.
+- All other options MUST NOT be set. If an application server receives a request containing the unsupported option USE-SESSION-KEY, it MUST return an error with the error code KRB\_AP\_ERR\_METHOD. If an application server receives a request containing any other unsupported options, it MUST return an error with the error code KRB\_ERR\_GENERIC. When MUTUAL-REQUIRED is set, the encrypted authenticator in the KRB\_AP\_REQ MUST contain the following field, which is optional in Kerberos:
+  - seq-number – MUST contain a pseudo-random number generated by the client (to be used as a nonce).
+
+The server MUST accept otherwise-valid KRB-AP-REQ messages that contain a seq-number in the range  $-2^{31}$  to  $-1$ .
+
+When MUTUAL-REQUIRED is not set, the encrypted authenticator MUST contain the following field that is optional in Kerberos:
+
+- sub-key – used to generate security parameters for the target protocol. The sub-key type MUST be set to  $-1^3$ . The actual sub-key length is dependent on the target protocol.
+
+When MUTUAL-REQUIRED is set, the target protocol is IPsec and the client is an MTA, the client MAY include the subkey field; in the case that the target protocol is IPsec and the client is other than an MTA, the client SHOULD include the subkey field. For IPsec, the subkey, if present, MUST contain a pseudo-random number of length 46 octets generated by the client.
+
+Other optional fields in the authenticator MUST NOT be present. If the authenticator contains the authorization-data field, the application server MUST return an error with the error code KRB\_ERR\_GENERIC. If the authenticator contains any other optional fields (apart from subkey and authorization-data), the application server MUST ignore those fields.
+
+The negative key type is used to indicate that it is application-specific and not defined in the Kerberos specification. When the Kerberos specification is updated to include this key type, the IPCablecom spec will be updated accordingly.
+
+The authenticator itself MUST be encrypted using 3-DES CBC with the Kerberos etype value: des3-cbc-md5 as specified in 6.4.2.2.
+
+In the encrypted part of the KRB\_AP\_REP, the optional sub-key field MUST be used for IPCablecom. Its type and format MUST be the same as when it appears in the KRB\_AP\_REQ (see above).
+
+The optional seq-number MUST be present, and MUST echo the value that was sent by the client in the KRB\_AP\_REQ. In this context, the seq-number field is used as a random nonce. The encrypted part of the KRB\_AP\_REP MUST be encrypted with the Kerberos etype value: des3-cbc-md5 as specified in 6.4.2.2.
+
+#### 6.5.2.3 Error handling
+
+##### 6.5.2.3.1 Error Reply
+
+If the Application Server is able to successfully parse the AP Request and the ticket that is inside of it, but the AP Request is rejected, it MUST return an error message. This error message MUST be formatted as the concatenation of the following fields:
+
+- Key Management Message ID – 1-byte value. Always set to 0x06.
+- Protocol Version – 1-byte value. The high-order nibble is the major version number and the lower-order nibble is the minor version number. For IPCablecom the major version number MUST be 1 and the minor version number MUST be 0.
+- Domain of Interpretation (DOI) – 1-byte value. Specifies the target protocol for which security parameters are established. See the table of DOI values in 6.5.2.
+- KRB\_ERROR – Kerberos error message as specified in IETF RFC 4120. It MUST include typed-data of REQ-SEQ to bind the error message to the sequence number from the authenticator in the AP-REQ message. The value encapsulated by the REQ-SEQ typed data MUST be the same as the value of the seq-number that was sent by the client in the KRB\_AP\_REQ. Also, the error message MUST include the optional e-cksum member, which is the keyed hash over the KRB\_ERROR message. The checksum type MUST be rsa-md5-des3, as specified in 6.4.3.1.
+
+---
+
+<sup>3</sup> The negative key type is used to indicate that it is application-specific and not defined in the Kerberos specification. When the Kerberos specification is updated to include this key type, the IPCablecom spec will be updated accordingly.
+
+If the error is application-specific (not a Kerberos-related error), then the KRB\_ERROR MUST include typed-data of type TD-APP-DEFINED-ERROR (value 106). The value of this typed-data is the following ASN.1 encoding (specified in IETF RFC 4120):
+
+```
+AppSpecificTypedData ::= SEQUENCE {  
+    oid           [0] OPTIONAL OBJECT IDENTIFIER,  
+                        -- identifies the application  
+    data-value    [1] OCTET STRING  
+                        -- application-specific data  
+}
+```
+
+Both the oid and the data-value fields inside AppSpecificTypedData are specified separately for each DOI.
+
+- Upon receiving this error reply, the client MUST verify both the keyed checksum and the REQ-SEQ field, to make sure that they match the seq-number field from the authenticator in the AP Request.
+
+If the Application Server is not able to successfully parse the AP Request and the ticket, it MUST drop the request and it MUST NOT return any response to the client. In case of a line error, the client will time out and re-send its AP Request. If the verification has failed, then the MTA MUST ignore this error message and continue waiting for the reply as if the error message was never received.
+
+When a client receives an error message, in some cases this Recommendation calls for the client to take some recovery steps and then send a new AP Request message. When a client is responding to an error message, it is not a retry and MUST NOT be considered to be part of the client's back-off and retry procedure specified in 6.4.8. The client MUST reset its timers accordingly, to reflect that the AP Request in response to an error message is not a retry.
+
+Although this Recommendation calls for an application server to return some specific error codes under certain error conditions, in the case when a server is repeatedly getting the same error from the same client IP address, it MAY at some point choose to stop sending back any further replies (errors or otherwise) to this client.
+
+##### 6.5.2.3.2 Clock skew error
+
+When the Application Server clock and the client clock are off by more than the limit for a clock skew, an error code KRB\_AP\_ERR\_SKEW MUST be returned. The value for the maximum clock skew allowed by the Application Server MUST NOT exceed 5 minutes. The optional client's time in the KRB\_ERROR MUST be filled out, and the client MUST compute the difference (in seconds) between the two clocks based upon the client and server time contained in the KRB\_ERROR message. The client SHOULD store this clock difference in non-volatile memory and MUST use it to adjust Kerberos timestamps in subsequent AP Request messages by adding the clock skew to its local clock value each time. The client MUST maintain a separate clock skew value for each realm and MAY share the same clock skew between the KDC and various application servers within that realm. The clock skew values are intended for uses only within the Kerberos protocol and SHOULD NOT otherwise affect the value of the local clock (since a clock skew is likely to vary from realm to realm).
+
+In the case that an AP Request failed due to a clock skew error, a client MUST immediately retry after adjusting the Kerberos timestamp inside the AP Request message.
+
+Additionally, the client MUST validate the time offset returned in the clock skew error, to make sure that it does not exceed a maximum allowable amount. This maximum time offset MUST not exceed 1 hour. This client check against a maximum time offset protects against an attack, where a rogue KDC attempts to fool an client into accepting an expired KDC certificate (later, during the next PKINIT exchange).
+
+##### **6.5.2.3.3 Handling ticket errors after a Wake Up**
+
+###### **6.5.2.3.3.1 KRB\_AP\_ERR\_BADKEYVER after a Wake Up**
+
+This clause addresses a scenario when an application server sends a Wake Up to a client and subsequently receives an AP Request that contains a ticket that is encrypted using an obsolete service key (results in the KRB\_AP\_ERR\_BADKEYVER error code). This error normally requires the client to get another ticket and retry, but in this particular scenario the client has to retry in the middle of a key management transaction.
+
+In this scenario, the application server MUST reply to the invalid AP Request with the KRB\_ERROR message with the KRB\_AP\_ERR\_BADKEYVER error code. Subsequent to the reply, the server MUST wait for another AP Request and MUST use the same time-out value that it would normally use when waiting for an AP Request. The client, upon getting back the above error code, MUST attempt to obtain a new ticket from the KDC (if the client has not done so already while waiting for server's reply) and if successful, MUST send another AP Request to the application server. If the client is unsuccessful in obtaining another ticket, it MUST not reply. If the server times out waiting for the second AP Request, it MUST proceed as if it timed out waiting for the original AP Request.
+
+If the application server is able to validate the second AP Request, it MUST then proceed as specified in 6.5.3. If the second AP Request again results in the KRB\_AP\_ERR\_BADKEYVER error, the server MUST abort key management with this client and not reply.
+
+###### **6.5.2.3.3.2 KRB\_AP\_ERR\_SKEW after a Wake Up**
+
+An application server is not required to check for a clock skew in this case, but if it does generate the KRB\_AP\_ERR\_SKEW, the same procedure MUST be followed as in 6.5.2.3.3.1, except that the client MUST retry after adjusting the timestamp (see 6.5.2.3.2) instead of getting a new ticket.
+
+### **6.5.3 Kerberized IPsec**
+
+This clause specifies the Kerberized key management profile specific to IPsec ESP in transport mode. IPsec uses the term "Security Association" (SA) to refer to a set of security parameters. IPsec Security Associations are always unidirectional and they MUST always be established in pairs within IPCablecom.
+
+An MTA MUST establish SAs with the IP address from where the corresponding Kerberized IPsec key management message (AP-REP or REKEY) has been received. Note that a CMS can notify an MTA that it is listening for NCS messages on a different port. Also, both the CMS and the MTA can send NCS messages from different ports, and the response must be sent to the port from which the message was sent. Kerberized Key Management does not allow for the negotiation of source or destination ports. Therefore SAs established to protect NCS signalling need to support multiple ports. One way to accomplish this is to establish two separate policies, outbound and inbound, in the IPsec Security Policy Database (see RFC 2367). Table 11 illustrates an example policy that would support changes in port numbers. Note that this table only illustrates inbound and outbound policies for NCS signalling between a specific MTA and a specific CMS. Table 11 is not a complete IPsec Security Policy Database. Other entries would be required to support communications over different protocols with the same host (e.g., Kerberized Key Management), communications with other hosts, or default policies for unknown hosts.
+
+**Table 11 – Example IPsec Security Policy Database Entries  
+for NCS Signalling between MTA and CMS**
+
+| <b>Direction</b>                                  | <b>Policy</b>   | <b>Source IP</b>  | <b>Source Port</b>                                     | <b>Destination IP</b> | <b>Destination Port</b>                                                                            |
+|---------------------------------------------------|-----------------|-------------------|--------------------------------------------------------|-----------------------|----------------------------------------------------------------------------------------------------|
+| Inbound – this applies to messages being received | Apply IPsec ESP | Remote IP address | Wildcard – any port                                    | Local IP address      | Bind to local port(s) that NCS messages will be sent from, and the provisioned NCS listening port. |
+| Outbound – this applies to messages being sent    | Apply IPsec ESP | Local IP address  | Bind to local port(s) that messages will be sent from. | Remote IP address     | Wildcard – any port                                                                                |
+
+The DOI value for IPsec MUST be set to 1.
+
+The ASD (Application-Specific Data) field in the AP Request key management message MUST be the SPI (Security Parameter Index) for the client's inbound Security Associations. It is a 4-byte integer value, MSB first.
+
+The ASD field in the AP Reply and Rekey key management messages MUST be the SPI for the server's inbound Security Associations. It is a 4-byte integer value, MSB first.
+
+The sub-key for IPsec MUST be a 46-byte value defined as follows:
+
+- If the AP-REQ does not include a sub-key, the 46-octet sub-key from AP-REP is taken as the subkey for IPsec.
+- If the AP-REQ does include a sub-key but no AP-REP (in the case of Rekey) is sent, then the 46-octet AP-REQ sub-key is used as the sub-key for IPsec.
+- Otherwise, both the AP-REQ and the AP-REP messages include 46-octet sub-keys, and their bit-by-bit XOR is the 46-byte sub-key for IPsec.
+
+An MTA MUST NOT perform Kerberized Key Management or establish IPsec Security Associations with a CMS when the pktcMtaDevCmsIpsecCtrl flag for that CMS is set to FALSE in the pktcMtaDevCmsTable. Note that this flag may only be set in the MTA configuration file and cannot be updated using SNMPv3. In the case of an NCS Redirect or any other dynamic method for associating a new CMS with an MTA endpoint where there is not an entry in the pktcMtaDevCmsTable for the new CMS, the MTA MUST perform Kerberized Key Management and establish IPsec Security Associations with the new CMS.
+
+The CMS MUST be capable of disabling its Kerberized Key Management interface. The CMS MUST NOT perform Kerberized Key Management or establish IPsec Security Associations when so configured.
+
+#### **6.5.3.1 Derivation of IPsec keys**
+
+After the Application Server sends out an AP Reply message, it is ready to derive a new set of IPsec keys. Similarly, after the client receives this AP Reply, it is ready to derive the same set of keys for IPsec. This clause specifies how the IPsec keys are derived from the Kerberos sub-key.
+
+The size of the Kerberos sub-key MUST be 46 bytes – the same as with the Secure Sockets Layer (SSL) or Transport Layer Security (TLS) pre-master secret.
+
+The IPsec ESP keys MUST be derived in the following order:
+
+- 1) Message authentication key for Client → Application Server messages;
+- 2) Encryption key for Client → Application Server messages;
+- 3) Message authentication key for Application Server → Client messages;
+
+- 4) Encryption key for Application Server → Client messages.
+
+For specific authentication and encryption algorithms that may be used by IPCablecom for IPsec, refer to 6.1.2.
+
+The derivation of the required keying material MUST be based on running a one-way pseudo-random function  $F(S, \text{"IPsec Security Association"})$  recursively until the right number of bits has been generated. Here,  $S$  is the Kerberos sub-key and the ASCII string "IPsec Security Association" is taken without quotes and without a terminating null character.  $F$  is defined in 9.6.
+
+#### 6.5.3.2 Periodic re-establishment of IPsec Security Associations
+
+An IPsec SA is defined with an expiration time  $T_{\text{EXP}}$  and a grace period  $GP_{\text{IPsec}}$ . The subclauses below specify how both the client and the Application Server handle the re-establishment of IPsec Security Associations (re-establish flag was TRUE in the AP Reply). When the re-establishment of IPsec SAs is required, there MUST always be at least one SA available for each direction and there MUST NOT be an interruption in the call signalling.
+
+##### 6.5.3.2.1 Periodic re-establishment of IPsec SAs at the client
+
+If the re-establish flag is set, the client MUST attempt to establish a new set of IPsec SAs (one for each direction) starting at the time  $T_{\text{EXP}} - GP_{\text{IPsec}}$ . At this time, the client MUST send an AP Request as specified in 6.5. The destination IP Address of the AP Request message MUST be the destination IP Address of the outbound IPsec SA that is about to expire. After the client receives an AP Reply, it MUST perform the following steps:
+
+- 1) Create new IPsec SAs, based on the negotiated ciphersuite, SPIs and on the established Kerberos subkey, from which the IPsec keys are derived as specified in 6.5. The expiration time for the outgoing SA MUST be set to  $T_{\text{EXP}}$ , while the expiration time for the incoming SA MUST be set to  $T_{\text{EXP}} + GP_{\text{IPsec}}$ .
+- 2) From this point forward, the new SA MUST be used for sending messages to the Application Server. The old SA that the client used for sending signalling messages to the Application Server MAY be explicitly removed at this time, or it MAY be allowed to expire (using an IPsec timer) at the time  $T_{\text{EXP}}$ .
+- 3) Continue accepting incoming signalling messages from the Application Server on both the old and the new incoming SAs, until the time  $T_{\text{EXP}} + GP_{\text{IPsec}}$ . After this time, the old incoming SA MUST expire. If a client receives a signalling message from the Application Server using a new incoming SA at an earlier time, it MAY at that time remove the old incoming SA.
+
+If the client fails to get any reply from the server and has to retry one or more times with another AP Request, the re-establish flag MUST be set to FALSE in each retry. This implies that when CMS processes a retry, it will remove any existing outgoing IPsec SAs, including the ones that may have been created after the processing of the initial AP Request, and proceed as if it is processing the SAs on demand (see 6.5.3.5.1).
+
+##### 6.5.3.2.2 Periodic re-establishment of IPsec SAs at the Application Server
+
+When an AP Request message is received with re-establish flag set, the Application Server MUST perform the applicable processing steps in 6.5.2. If the client is an MTA, the Application Server MUST also verify that the source IP address in the received datagram of the AP Request message is the same IP address as was used when the initial SA was established. The Application Server MUST ignore the AP Request if the IP addresses do not match.
+
+In addition, the Application Server MUST perform the following steps, in the specified order immediately before an AP Reply is returned.
+
+- 1) Create new IPsec SAs, based on the negotiated ciphersuite, SPIs and on the established Kerberos sub-key, from which the IPsec keys are derived as specified in 6.5.
+- 2) Send back an AP Reply.
+- 3) Continue sending signalling messages to the client using an old outgoing SA until the time  $T_{\text{EXP}}$ . During the same period, accept incoming messages from either the old or the new incoming SA.
+- 4) At the time  $T_{\text{EXP}}$  both the old incoming and the old outgoing SAs MUST expire. At the time  $T_{\text{EXP}}$ , the Application Server MUST switch to the new SA for outgoing signalling messages to the client. If for some reason the new IPsec SAs were not established successfully, there would not be any IPsec SAs that are available after this time.
+
+#### 6.5.3.3 Expiration of IPsec SAs
+
+An IPsec SA is defined with an expiration time  $T_{\text{EXP}}$  and a grace period  $GP_{\text{IPsec}}$ . This clause specifies how both the client and the Application Server MUST handle the expiration of IPsec Security Associations (re-establish flag was FALSE in the AP Reply).
+
+At the Client:
+
+- Outgoing SA expires at  $T_{\text{EXP}}$
+- Incoming SA expires at  $T_{\text{EXP}} + GP_{\text{IPsec}}$
+
+At the Application Server:
+
+- Outgoing SA expires at  $T_{\text{EXP}}$
+- Incoming SA expires at  $T_{\text{EXP}} + GP_{\text{IPsec}}$
+
+Whenever an IPsec SA has been expired and a signalling message needs to be sent by either the client or the Application Server, the key management layer MUST be signalled to establish a new IPsec SA. It is established using the same procedures as the ones specified in 6.5.3.5.
+
+#### 6.5.3.4 Initial establishment of IPsec SAs
+
+When a client is rebooted, it does not have any current IPsec SAs established with the Application Server, since IPsec SAs are not saved in non-volatile memory. In order to re-establish them, it MUST go through the recovery procedure that is described in 6.5.3.5.
+
+#### 6.5.3.5 On-demand establishment of IPsec SAs
+
+This clause describes the recovery steps that MUST be taken in the case that an IPsec SA is somehow lost and needs to be re-established.
+
+##### 6.5.3.5.1 Client loses an outgoing IPsec SA
+
+If a client attempts to send a signalling message to the Application Server without a valid IPsec SA, the IPsec layer in the client will realize the SA is missing and returns an error back to the signalling application<sup>4</sup>. In this case, the following recovery steps MUST be taken at the key management layer:
+
+- 1) The client first makes sure that it has a valid Kerberos ticket for the Application Server. If not, it must first perform a PKINIT exchange as specified in 6.4.2.
+
+---
+
+<sup>4</sup> In this case, there are no actual messages exchanged between the MTA and the application server (e.g., CMS).
+
+- 2) Client sends a new AP Request to the Application Server and gets back an AP Reply, as specified in 6.5.2. After the receipt of an AP Reply, the client MUST:
+  - create new IPsec SAs;
+  - remove any old outgoing IPsec SAs;
+  - be prepared to use both of the newly created IPsec SAs.
+- 3) If the Kerberos ticket includes the optional caddr field and the caddr does not contain a matching source IP address for the AP Request datagram, the Application Server MUST ignore the request.
+- 4) The Application Server also MUST NOT set the ACK-required flag in the AP Reply. Right after sending out an AP Reply, the Application Server MUST be prepared to both send and receive messages on the newly created SAs.
+- 5) After receiving this AP Request (with Re-establish flag = FALSE), the Application Server MUST remove any existing outgoing IPsec SAs that it might already have for this client.
+
+The key management application running on the client MUST send an explicit signal to the signalling application, when it completes the re-establishment of the IPsec SAs.
+
+##### 6.5.3.5.2 Client loses an incoming IPsec SA
+
+When the client receives an IP packet from an Application Server on an unrecognized IPsec SA, the client MUST ignore this error and the packet MUST be dropped.
+
+##### 6.5.3.5.3 Application Server loses an outgoing IPsec SA
+
+When an Application Server attempts to send a signalling message to the client, and the IPsec layer in the Application Server realizes a valid SA is missing, the IPsec layer MUST return an error back to the signalling application<sup>5</sup>. In this case, the following recovery steps MUST be taken at the key management layer:
+
+- 1) Application Server sends a Wake Up message to the client.
+- 2) The client makes sure that it has a valid Kerberos ticket for the Application Server. If not, it MUST first obtain it from the KDC.
+- 3) Client sends a new AP Request to the Application Server, as specified in 6.5.2. If the Kerberos ticket includes the optional caddr field and the caddr does not contain a matching source IP address for the AP Request datagram, the Application Server MUST ignore the request.
+- 4) For each AP Request, the client generates a nonce and puts it into the seq-number field. As specified in 6.5.2, the client will save this nonce for a period of time specified by the pktcMtaDevCmsSolicitedKeyTimeout MIB object, and wait for a matching AP Reply (this is not the same nonce as the Server-nonce received in the Wake Up). However, after this time-out, the client MUST NOT retry and MUST abort an attempt to establish a IPsec SA in response to a received Wake Up.
+
+Once the client gets back a matching AP Reply, it will be in the format specified in 6.5.2. The ACK-required flag in the AP Reply MUST be set, to insure that the client replies with the SA Recovered message in the following step. If this client previously had any outgoing IPsec SAs with this Application Server IP address, they MUST be removed at this time. If the client previously had a timer set for automatic refresh of IPsec SAs with this Application Server IP address, that automatic refresh MUST be reset or disabled. The client MAY start using both of the newly created SAs. If the AP Reply had the Re-establish flag
+
+<sup>5</sup> In this case, there are no actual messages exchanged between the MTA and the CMS or other application server.
+
+set, the client MUST be prepared to automatically re-establish new IPsec SAs, as specified in 6.5.3.2.
+
+- 5) The Application Server can receive signalling messages from the client on the new incoming SA, but cannot yet start using an outgoing SA for sending messages to the client.
+- 6) Immediately after the client establishes the new IPsec SAs, it MUST send a SA Recovered message to the Application Server.
+- 7) Upon receipt of this message, the Application Server MUST immediately activate the new outgoing SA for sending signalling messages to the client.
+
+The key management application running on the Application Server MUST send an explicit signal to the signalling application when it completes the re-establishment of the IPsec SAs.
+
+##### 6.5.3.5.4 Application Server loses an incoming IPsec SA
+
+When the Application Server receives an IP packet from a client on an unrecognized IPsec SA, the Application Server MUST ignore this error and the packet MUST be dropped. In this case, any attempt at recovery (e.g., establishing a new SA) is prone to denial-of-service attacks.
+
+#### 6.5.3.6 IPsec-specific errors returned in KRB\_ERROR
+
+Inside AppSpecificTypedData the oid field MUST be set to:
+
+```
+enterprises (1.3.6.1.4.1) cableLabs (4491) clabProjects (2) clabProjPacketCable  
+(2) pktcSecurity (4) errorCodes (1) ipSec (1)
+```
+
+The data-value field MUST correspond to the following typed-data value:
+
+```
+pktcKrbIpsecError ::= SEQUENCE {  
+    e-code    [0]      INTEGER,  
+    e-text    [1]      GeneralString OPTIONAL,  
+    e-data    [2]      OCTET STRING OPTIONAL  
+}
+```
+
+The e-code field MUST correspond to one of the following error code values:
+
+|                         |    |                                           |
+|-------------------------|----|-------------------------------------------|
+| KRB_IPSEC_ERR_NO_POLICY | 1  | No IPsec policy defined for request       |
+| KRB_IPSEC_ERR_NO_CIPHER | 2  | No support for requested ciphersuites     |
+| KRB_IPSEC_NO_SA_AVAIL   | 3  | No IPsec SA available (i.e., SAD is full) |
+| KRB_IPSEC_ERROR_GENERIC | 16 | Generic KRB IPsec error                   |
+
+The optional e-text field can be used for informational purposes (i.e., logging, network troubleshooting) and the optional e-data field is reserved for future use to transport any application data associated with a specific error.
+
+### 6.5.4 Kerberized SNMPv3
+
+This clause specifies the Kerberized key management profile specific to SNMPv3; see RFC 3414. In the case of SNMPv3, the security parameters are associated with the usmUserName (SNMPv3 user name), the agent's usmUserEngineID (SNMPv3 engine ID) and the manager's usmUserEngineID.
+
+Multiple SNMP managers on different hosts but with the same user name are considered as unique Kerberos principals. Still, the SNMPv3 keys generated by any one of these SNMP managers MUST be shared across all the managers – as long as they apply to the same SNMPv3 user name and the same SNMPv3 engine ID (of the agent).
+
+The security parameters consist of a single authentication key, a single privacy (encryption) key, SNMPv3 boot count and engine time. SNMPv3 privacy can be turned off by selecting a NULL encryption transform.
+
+The DOI value for SNMPv3 MUST be set to 2.
+
+The ASD field in the AP Request message MUST be set to the concatenation of the fields as shown in Table 12:
+
+**Table 12 – Required format for data in the AP Request**
+
+| Attribute                   | Length                      |
+|-----------------------------|-----------------------------|
+| Agent's snmpEngineID Length | 1 byte                      |
+| Agent's snmpEngineID        | Variable                    |
+| Agent's snmpEngineBoots     | 4 bytes, network byte order |
+| Agent's snmpEngineTime      | 4 bytes, network byte order |
+| usmUserName Length          | 1 byte                      |
+| usmUserName                 | Variable                    |
+
+The ASD field in the AP Reply message MUST be set to the concatenation of the fields as shown in Table 13:
+
+**Table 13 – Required format for data in the AP Reply**
+
+| Attribute                     | Length                      |
+|-------------------------------|-----------------------------|
+| Manager's snmpEngineId Length | 1 byte                      |
+| Manager's snmpEngineId        | Variable                    |
+| Manager's snmpEngineBoots     | 4 bytes, network byte order |
+| Manager's snmpEngineTime      | 4 bytes, network byte order |
+| usmUserName Length            | 1 byte                      |
+| usmUserName                   | Variable                    |
+
+For IPCablecom MTAs, the usmUserName contains in it the MTA MAC address (see ITU-T Rec. J.167). The manager MUST verify that this MAC address and the MTA FQDN specified in the MTA principal name match. The manager MUST also verify that any SNMP INFORM message containing a MAC address, from the MTA contains a correct MAC address – the same one that is in the usmUserName.
+
+The usmUserName field inside the Application-specific data field in the AP Reply MUST be the same as the one in the preceding AP Request.
+
+The Rekey message is not used for SNMPv3 key management.
+
+The sub-key for SNMPv3 MUST be a 46-byte value.
+
+#### **6.5.4.1 Derivation of SNMPv3 keys**
+
+After the server sends out an AP Reply message, it is ready to derive a new set of SNMPv3 keys. Similarly, after the client receives this AP Reply, it is ready to derive the same set of keys for SNMPv3. This clause specifies how the SNMPv3 keys are derived from the Kerberos sub-key.
+
+The size of the Kerberos sub-key MUST be 46 bytes.
+
+The derived SNMPv3 Keys MUST be as follows, in the specified order:
+
+- SNMPv3 authentication key;
+- SNMPv3 privacy key.
+
+For specific authentication and encryption algorithms that may be used by IPCablecom for SNMPv3, refer to 6.3.
+
+The derivation of the required keying material MUST use a one-way pseudo-random function  $F(S, \text{"SNMPv3 Keys"})$  recursively until the right number of bits has been generated. Here,  $S$  is the subkey and the string "SNMPv3 Keys" is taken without quotes and without a terminating null character.  $F$  is defined in 9.6.
+
+#### **6.5.4.2 Periodic re-establishment of SNMPv3 keys**
+
+Periodic re-establishment of SNMPv3 keys, where the next set of keys is created before the old one expired, is currently not supported by IPCablecom. The re-establish flag in the AP Reply key management message MUST be set to FALSE.
+
+#### **6.5.4.3 Expiration of SNMPv3 keys**
+
+Expiration of SNMPv3 keys is currently not supported by IPCablecom. The values of the Security Parameters Lifetime and Grace Period fields in the AP Reply MUST be set to 0.
+
+#### **6.5.4.4 Initial establishment of SNMPv3 keys**
+
+When a client is rebooted, it may not have any saved SNMPv3 keys established with the SNMP Manager. In order to re-establish them, it goes through the recovery procedure that is described in 6.5.4.5.1.
+
+#### **6.5.4.5 Error recovery**
+
+This clause describes the recovery steps that must be taken in the case that SNMPv3 keys are somehow lost and need to be re-established.
+
+##### **6.5.4.5.1 SNMP agent wishes to send with missing SNMPv3 keys**
+
+In the case of SNMP, an SNMP agent is not responsible for re-establishing SNMPv3 keys because it does not send unsolicited requests to the Provisioning Server after the initial provisioning is done. Still, an SNMP agent could attempt to re-establish SNMPv3 keys after it gets an SNMPv3 authentication error back from the SNMP manager. If the SNMP agent determines that it has incorrect SNMPv3 keys, it MUST perform the following steps before it is able to send out an SNMP message:
+
+- 1) The agent first makes sure that it has a valid Kerberos ticket for the Application Server. If not, it must first obtain it as specified in 6.5.2.
+- 2) The agent sends a new AP Request to the manager and gets back an AP Reply, as specified in 6.5.2. After the receipt of the AP Reply the agent is prepared to use the newly created SNMPv3 keys. In this scenario, the SNMP manager MUST NOT set an ACK-required flag in the AP Reply. Right after sending out an AP Reply, the manager is prepared to both send and receive messages with the new SNMPv3 keys. After receiving this AP Request (with Re-establish flag = FALSE), the manager MUST remove its previous set of SNMPv3 keys that it might already have for this agent (and for this SNMPv3 user name).
+
+It is possible that the SNMP manager already initiated key management (with a Wake Up) but instead receives an unsolicited AP Request from the agent (with server-nonce = 0). This unlikely scenario might occur if the manager and the agent decide to initiate key management at about the same time. In this case, the SNMP manager MUST ignore the unsolicited AP Request message and continue waiting for the one that is in response to a Wake Up.
+
+##### **6.5.4.5.2 SNMP agent receives with missing SNMPv3 keys**
+
+If the SNMP agent receives a request from a SNMP manager and is unable to find SNMPv3 keys for the specified USM User Name, the agent MUST process the SNMP message according to RFC 3414 and RFC 3412.
+
+##### 6.5.4.5.3 SNMP manager wishes to send with missing SNMPv3 keys
+
+SNMP manager attempts to send a message to the agent and does not find the desired user's SNMPv3 keys (or considers the existing SNMPv3 keys invalid or compromised). In this case, the following recovery steps MUST be taken at the key management layer:
+
+- 1) The manager sends a Wake Up message to the agent.
+- 2) The agent makes sure that it has a valid Kerberos ticket for the manager. If not, it MUST first obtain it from the KDC.
+- 3) The agent sends a new AP Request to the manager, as specified in 6.5.2. For each AP Request, the agent generates a nonce and puts it into the seq-number field. As specified in 6.5.3.5.3, the agent will save this nonce for a period of time specified by the pktcMtaDevProvSolicitedKeyTimeout MIB object and wait for a matching AP Reply (this is not the same nonce as the server-nonce received in the Wake Up). However, after this time-out, the agent MUST NOT retry and MUST abort an attempt to establish SNMPv3 keys in response to a received Wake Up.
+
+Once the agent gets back a matching AP Reply, it will be in the format specified in 6.5.2. The ACK-required flag in the AP Reply MUST be set, to ensure that the agent replies with the SA Recovered message in the following step. If this agent previously had SNMPv3 keys for the specified SNMPv3 user, they MUST be removed at this time.
+
+- 4) After the receipt and validation of the AP Reply, the agent sends an SA Recovered message to the manager. At this time the agent will be ready to use the new SNMPv3 keys and will enable SNMPv3 security.
+- 5) Upon receipt of the SA Recovered message, the manager will immediately activate the new set of SNMPv3 keys and will enable SNMPv3 security.
+
+It is possible that the SNMP agent already initiated key management (with an unsolicited AP Request) but instead receives a Wake Up from the manager. This unlikely scenario might occur if the manager and the agent decide to initiate key management at about the same time. In this case, the SNMP agent MUST abort waiting for the reply to the unsolicited AP Request message and instead generate a new AP Request in response to the Wake Up.
+
+If an SNMP agent receives a second Wake Up message from a different SNMP manager (FQDN or IP address) before the first key management session has been completed, the SNMP agent MUST ignore the second Wake Up message.
+
+#### 6.5.4.6 SNMPv3-specific errors returned in KRB\_ERROR
+
+Inside AppSpecificTypedData, the oid field MUST be set to:
+
+enterprises (1.3.6.1.4.1) cableLabs (4491) clabProjects (2) clabProjPacketCable (2) pktcSecurity (4) errorCodes (1) snmpv3 (2)
+
+The data-value field MUST correspond to the following typed-data value:
+
+```
+pktcKrbSnmpv3Error ::= SEQUENCE {  
+    e-code [0] INTEGER,  
+    e-text [1] GeneralString OPTIONAL,  
+    e-data [2] OCTET STRING OPTIONAL  
+}
+```
+
+The e-code field MUST correspond to one of the following error code values:
+
+|                          |    |                                       |
+|--------------------------|----|---------------------------------------|
+| KRB_SNMPV3_ERR_USER_NAME | 1  | Unrecognized SNMPv3 user name         |
+| KRB_SNMPV3_ERR_NO_CIPHER | 2  | No support for requested ciphersuites |
+| KRB_SNMPV3_ERR_ENGINE_ID | 3  | Invalid SNMPv3 Engine ID specified    |
+| KRB_SNMPV3_ERROR_GENERIC | 16 | Generic KRB SNMPv3 error              |
+
+The optional e-text field can be used for informational purposes (i.e., logging, network troubleshooting) and the optional e-data field is reserved for future use to transport any application data associated with a specific error.
+
+## 6.6 End-to-end security for RTP
+
+RTP security is currently fully specified in 7.6.2.1. Key management for RTP requires that both the (encryption) Transform ID and the Authentication Algorithm are specified, analogous to the IPsec key management. This clause lists in Tables 14 and 15, respectively, the Transform IDs and Authentication Algorithms that are available for RTP security.
+
+**Table 14 – RTP Packet Transform Identifiers**
+
+| Transform ID    | Value   | Key size (in bits) | MUST support | Description                                 |
+|-----------------|---------|--------------------|--------------|---------------------------------------------|
+| RTP_ENCR_NULL   | 0x50    | NA                 | Yes          | Encryption turned off                       |
+| RTP_AES         | 0x51    | 128                | Yes          | AES-128 in CBC mode with 128-bit block size |
+| RTP_XDESX_CBC   | 0x53    | 192                | No           | DESX-XEX-CBC                                |
+| RTP_DES_CBC_PAD | 0x54    | 128                | No           | DES-CBC-PAD                                 |
+| RTP_3DES_CBC    | 0x56    | 128                | No           | 3DES-EDE-CBC                                |
+| Reserved        | 0x57-59 | –                  | –            |                                             |
+
+The RTP\_AES and RTP\_ENCR\_NULL Transform IDs MUST be supported. AES-128 MUST be used in CBC mode with a 128-bit block size and an Initialization Vector (IV) generated in accordance with 7.6.2.1.2.2.2. AES-128 requires 10 rounds of cryptographic operations (see FIPS PUB 197).
+
+**Table 15 – RTP IPCablecom Authentication Algorithms**
+
+| Authentication Algorithm | Value | Key size (in bits)              | MUST support | Description               |
+|--------------------------|-------|---------------------------------|--------------|---------------------------|
+| AUTH_NULL                | 0x60  | 0                               | Yes          | Authentication turned off |
+| Reserved                 | 0x61  | –                               | –            |                           |
+| RTP_MMH_2                | 0x62  | Variable<br>(see 7.6.2.1.2.1.1) | Yes          | 2-byte MMH MAC            |
+| Reserved                 | 0x63  | –                               | –            |                           |
+| RTP_MMH_4                | 0x64  | Variable<br>(see 7.6.2.1.2.1.1) | Yes          | 4-byte MMH MAC            |
+| Reserved                 | 0x65  | –                               | –            |                           |
+
+The Authentication Algorithms AUTH\_NULL, RTP\_MMH\_2 and RTP\_MMH\_4 MUST be supported.
+
+## 6.7 End-to-end security for RTCP
+
+RTCP security is currently fully specified in 7.6.2.2. Key management for RTCP requires that both the (encryption) Transform ID and the Authentication Algorithm be specified. This clause lists in Tables 16 and 17, respectively, the Transform IDs and Authentication Algorithms that are available for RTCP security.
+
+**Table 16 – RTCP Packet Transform Identifiers**
+
+| <b>Transform ID</b> | <b>Value</b> | <b>Key size (in bits)</b> | <b>MUST support</b> | <b>Description</b>                          |
+|---------------------|--------------|---------------------------|---------------------|---------------------------------------------|
+| RTCP_ENCR_NULL      | 0x70         | –                         | Yes                 | Encryption turned off.                      |
+| AES-CBC             | 0x71         | 128                       | Yes                 | AES-128 in CBC mode with 128-bit block size |
+| XDESX-CBC           | 0x72         | 192                       | No                  | DESX-XEX-CBC                                |
+| DES-CBC-PAD         | 0x73         | 128                       | No                  | DES-CBC-PAD                                 |
+| 3DES-CBC            | 0x74         | 128                       | No                  | 3DES-EDE-CBC                                |
+| Reserved            | 0x75-7f      | –                         | –                   |                                             |
+
+The AES-CBC and RTCP\_ENCR\_NULL Transform IDs MUST be supported. AES-128 MUST be used in CBC mode with a 128-bit block size and a randomly generated Initialization Vector (IV). AES-128 requires 10 rounds of cryptographic operations (see FIPS PUB 197).
+
+**Table 17 – RTCP Authentication Algorithms**
+
+| <b>Transform ID</b> | <b>Value</b> | <b>Key size (in bits)</b> | <b>MUST support</b> | <b>Description</b>                           |
+|---------------------|--------------|---------------------------|---------------------|----------------------------------------------|
+| RTCP_AUTH_NULL      | 0x80         | N/A                       | Yes                 | Authentication turned off.                   |
+| HMAC-SHA1-96        | 0x81         | 160                       | Yes                 | First 12 bytes of the HMAC-SHA1 per RFC 2404 |
+| HMAC-MD5-96         | 0x82         | 128                       | No                  | First 12 bytes of the HMAC-MD5 per RFC 2403  |
+| Reserved            | 0x83-8f      | –                         | –                   |                                              |
+
+The HMAC-SHA1-96 and RTCP\_AUTH\_NULL authentication algorithms MUST be supported.
+
+## 6.8 BPI+
+
+All E-MTAs and S-MTAs MUST use J.112-compliant cable modems and MUST implement BPI+ (ITU-T Rec. J.125). Baseline Privacy Plus (BPI+) provides security services to the J.112 data link layer traffic flows running across the cable access network, i.e., between CM and CMTS. These services are message confidentiality and access control. The BPI+ security services operating in conjunction with J.112 provide cable modem users with data privacy across the cable network and protect cable operators from theft of service.
+
+The protected J.112 MAC data communication services fall into three categories:
+
+- best-effort, high-speed, IP data services;
+- QoS (e.g., constant bit rate) data services; and
+- IP multicast group services.
+
+When employing BPI+, the CMTS protects against unauthorized access to these data transport services by:
+
+- 1) enforcing encryption of the associated traffic flows across the cable network; and
+- 2) authenticating the J.112 MAC management messages that CMs use to establish QoS service flows.
+
+BPI+ employs a client/server key management protocol in which the CMTS (the server) controls distribution of keying material to client CMs. The key management protocol ensures that only authorized CMs receive the encryption and authentication keys needed to access the protected services.
+
+Baseline Privacy Plus has two component protocols:
+
+- An encapsulation protocol for encrypting packet data across the cable network. This protocol defines:
+  - 1) the frame format for carrying encrypted packet data within J.112 MAC frames;
+  - 2) a set of supported *cryptographic suites*, i.e., pairings of data encryption and authentication algorithms; and
+  - 3) the rules for applying those algorithms to a J.112 MAC frame's packet data.
+- A key management protocol (Baseline Privacy Key Management, or "BPKM") provides the secure distribution of keying data from CMTS to CMs. Through this key management protocol, CM and CMTS synchronize keying data; in addition, the CMTS uses the protocol to enforce conditional access to network services.
+
+Baseline Privacy Plus does not provide any security services beyond the J.112 cable access network. The majority of IPCablecom's signalling and media traffic flows, however, take paths that traverse the managed IP "backhaul" networks, which lie behind CMTSs. Since J.112 and IPCablecom service providers typically will not guarantee the security of their managed IP backhaul networks, the IPCablecom security architecture defines end-to-end security mechanisms for all these flows. End-to-end security is provided at the Network layer through IPsec, or, in the case of Client media flows, at the application/transport layer through RTP application layer security. Thus, IPCablecom does not rely on BPI+ to provide security services to its component protocol interfaces.
+
+## 6.9 TLS
+
+### 6.9.1 Overview
+
+The TLS protocol (RFC 2246) provides privacy and data integrity over a reliable transport layer protocol such as TCP. The protocol is composed of two layers: the TLS Record Protocol and the TLS Handshake Protocol. The TLS Record Protocol is used to securely encapsulate upper layer protocols, while the TLS Handshake Protocol provides the key management functionality required to establish TLS sessions.
+
+In IPCablecom, TLS is used to secure SIP-based signalling between SIP endpoints such as the CMS and EBPs.
+
+### 6.9.2 IPCablecom profile for TLS with SIP
+
+Unless specified within this Recommendation, IPCablecom SIP interfaces requiring TLS MUST be compliant with the TLS specification (RFC 2246) and any requirements specified in RFC 3261 relating to its usage in SIP.
+
+TLS supports the negotiation and use of compression methods. However, since these methods are not specified within TLS, compression MUST NOT be used in IPCablecom.
+
+#### 6.9.2.1 TLS ciphersuites
+
+In TLS, the ciphersuite includes the authenticated key agreement (AKE) method used in the TLS handshake, as well as encryption and authentication ciphers used to secure the record layer. Ciphersuites are negotiated with the TLS client presenting a list of supported ciphersuites in the Client Hello message, and the server responding with the selected ciphersuite in the Server Hello message.
+
+Table 18 describes the TLS ciphersuites defined in RFC 2246 and RFC 3268 supported by IPCablecom:
+
+**Table 18 – TLS ciphersuites**
+
+| <b>TLS Ciphersuite</b>            | <b>Support</b> | <b>AKE method</b>                                         | <b>Encryption</b> | <b>Auth.</b> |
+|-----------------------------------|----------------|-----------------------------------------------------------|-------------------|--------------|
+| TLS_RSA_WITH_AES_128_CBC_SHA      | MUST           | RSA                                                       | AES-128<br>CBC    | SHA          |
+| TLS_DHE_RSA_WITH_AES_128_CBC_SHA  | MUST           | Ephemeral<br>Diffie-<br>Hellman<br>with RSA<br>signatures | AES-128<br>CBC    | SHA          |
+| TLS_RSA_WITH_3DES_EDE_CBC_SHA     | SHOULD         | RSA                                                       | 3DES CBC          | SHA          |
+| TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA | SHOULD         | Ephemeral<br>Diffie-<br>Hellman<br>with RSA<br>signatures | 3DES CBC          | SHA          |
+
+#### **6.9.2.2 IPCablecom TLS Certificates**
+
+TLS is a client-server based protocol with optional client authentication. However, in IPCablecom, mutual authentication using RSA-based certificates MUST be used. The TLS server MUST send a Certificate Request to the client. Both the TLS client and server certificates MUST conform to the IPCablecom Server Certificate as specified in 8.2.3.4.3.
+
+IP Cablecom Server Certificates include a server identifier (based on FQDN or IP address) embedded within the CN of the Subject Name field. Before accepting or continuing with a TLS connection, the TLS server or client MUST validate the remote server identifier to ensure it matches the IP address used for the TCP/TLS connection, in addition to any other local policy (i.e., provisioned list of allowed remote TLS endpoints based on FQDN or IP address).
+
+In addition to the CableLabs Service Provider Root certificate, a TLS implementation MAY support a list of trusted CAs (Certificate Authorities) to facilitate inter-working between IPCablecom domains (i.e., between Server Providers).
+
+#### **6.9.2.3 Connection persistence and re-use**
+
+Since TCP connection and TLS session establishment (which relies on TCP) can be quite costly both in terms of performance and network latency, they are not suited for on-demand SIP signalling. As such, TLS sessions SHOULD be kept persistent as much as possible and SIP connection re-use SHOULD be supported.
+
+#### **6.9.2.4 Session caching**
+
+In TLS, it is possible to resume a previous session if it has been cached on both the TLS client and server. Resuming sessions drastically speeds up the session establishment, as fewer messages are exchanged and authentication is based on symmetric key cryptography.
+
+In IPCablecom, TLS session caching SHOULD be supported. A TLS client initiating a TLS session MUST attempt to resume a cached session if it has retained a session for the remote server. The duration for which a TLS client or server must retain a cached session is a local policy and implementation specific.
+
+# 7 Security profile
+
+The IPCablecom architecture defines over half a dozen networked components and the protocol interfaces between them. These networked components include the media terminal adapter (MTA), call management server (CMS), signalling gateway (SG), media gateway (MG) and a variety of OSS systems (DHCP, TFTP and DNS servers, network management systems, provisioning servers, etc.). IPCablecom security addresses the security requirements of each constituent protocol interface by:
+
+- identifying the threat model specific to each constituent protocol interface;
+- identifying the security services (authentication, authorization, confidentiality, integrity, non-repudiation) required to address the identified threats;
+- for each constituent protocol interface, specifying the particular security mechanism providing the required security services.
+
+Clause 5.2 summarizes the threat models applicable to IPCablecom's protocol interfaces. In this clause, we identify the security service requirements of each protocol interface and security mechanisms providing those services.
+
+The security mechanisms include both the security protocol (e.g., IPsec, RTP-layer security, SNMPv3 security) and the supporting key management protocol (e.g., IKE, PKINIT/Kerberos).
+
+The security analysis in 5.3.3 is organized by functional categories. For each functional category, we identify the constituent protocol interfaces, the security services required by each interface, and the particular security mechanism employed to deliver those security services. Each per-protocol security description includes the detailed information sufficient to ensure interoperability. This includes cryptographic algorithms and cryptographic parameters (e.g., key lengths).
+
+As a convenient reference, each functional category's security analysis includes a summary security profile matrix of the following form (Media security profile matrix shown) in Table 19:
+
+**Table 19 – RTP – RTCP Security Profile Matrix**
+
+|                     | <b>RTP (MTA-MTA,<br/>MTA-PSTN GW)</b>                                                                                                                                                                                                                 | <b>RTCP (MTA-MTA,<br/>MTA-MG, MG-MG)</b>                                                                                                                                                                                                                                                                                                                    |
+|---------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Authentication      | Optional (indirect)                                                                                                                                                                                                                                   | Optional (indirect)                                                                                                                                                                                                                                                                                                                                         |
+| Access control      | Optional                                                                                                                                                                                                                                              | Optional                                                                                                                                                                                                                                                                                                                                                    |
+| Integrity           | Optional                                                                                                                                                                                                                                              | Yes                                                                                                                                                                                                                                                                                                                                                         |
+| Confidentiality     | Yes                                                                                                                                                                                                                                                   | Yes                                                                                                                                                                                                                                                                                                                                                         |
+| Non-repudiation     | No                                                                                                                                                                                                                                                    | No                                                                                                                                                                                                                                                                                                                                                          |
+| Security mechanisms | Application Layer Security via RTP<br>IPCablecom Security Profile keys distributed over secured MTA-CMS links<br>AES-128 encryption algorithm<br>Optional 2-byte or 4-byte MAC based on MMH algorithm<br>IPCablecom supports ciphersuite negotiation. | Application Layer Security via RTCP<br>IPCablecom Security Profile keys distributed over secured MTA-CMS links<br>RTCP ciphersuites are negotiated separately from the RTP ciphersuites and include both encryption and message authentication algorithms.<br>Keys are derived from the end-end secret using the same mechanism as used for RTP encryption. |
+
+Each matrix column corresponds to a particular protocol interface. All but the last row corresponds to a particular security service; the cell contents in these rows indicate whether the protocol interface requires the corresponding security service. The final row summarizes the security mechanisms selected to provide the required services.
+
+Note that the protocol interface column headings not only identify the protocol, but also indicate the network components the protocols run between.
+
+## **7.1 Device and service provisioning**
+
+Device provisioning is the process by which an MTA is configured to support voice communications service. The MTA provisioning process is specified in ITU-T Rec. J.167.
+
+Figure 10 illustrates only the flows involved with the Secure provisioning processes. The provisioning Recommendation lays out in detail these Secure Provisioning flows along with two non-secure MTA provisioning flows called Basic and Hybrid. The Secure Provisioning flows involving security mechanisms are described in this clause. Refer to ITU-T Rec. J.167 for the non-secure flows.
+
+![](e8f5117fb031f413a836525061addd61_img.jpg)
+
+| Flows                                               | CM / MTA | AN                                                                                   | J.112 DHCP | J.112 TFTP | J.112 ToD | Prov Server | PKT DHCP | PKT DNS | PKT TFTP | MSO KDC          | CMS | Telephony Provider KDC | SYSLOG |
+|-----------------------------------------------------|----------|--------------------------------------------------------------------------------------|------------|------------|-----------|-------------|----------|---------|----------|------------------|-----|------------------------|--------|
+| <b>Start with J.112 Initialization/Registration</b> |          |                                                                                      |            |            |           |             |          |         |          |                  |     |                        |        |
+| CM-1                                                |          | DHCP Broadcast Discover (Option Code 60 w/ MTA device identifier)                    |            |            |           |             |          |         |          |                  |     |                        |        |
+| CM-2                                                |          | DHCP Offer (Option Code 177 w/ Telephony Service Provider's DHCP server address)     |            |            |           |             |          |         |          |                  |     |                        |        |
+| CM-3                                                |          | DHCP Request (device ID, e.g., MAC Address)                                          |            |            |           |             |          |         |          |                  |     |                        |        |
+| CM-4                                                |          | DHCP ACK (CM IP, ftp srv addr, CM Configuration filename)                            |            |            |           |             |          |         |          |                  |     |                        |        |
+| CM-5                                                |          | J.112 CM config file request                                                         |            |            |           |             |          |         |          |                  |     |                        |        |
+| CM-6                                                |          | J.112 config file                                                                    |            |            |           |             |          |         |          |                  |     |                        |        |
+| CM-7                                                |          | ToD Request                                                                          |            |            |           |             |          |         |          |                  |     |                        |        |
+| CM-8                                                |          | ToD Response                                                                         |            |            |           |             |          |         |          |                  |     |                        |        |
+| CM-9                                                |          | CM registration with AN                                                              |            |            |           |             |          |         |          |                  |     |                        |        |
+| CM-10                                               |          | AN Registration ACK                                                                  |            |            |           |             |          |         |          |                  |     |                        |        |
+| <b>Complete J.112 Initialization/Registration</b>   |          |                                                                                      |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-1                                               |          | DHCP Broadcast Discover (Option Code 60 w/ MTA device identifier)                    |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-2                                               |          | DHCP Offer (Option Code 177 w/ name of provisioning realm)                           |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-3                                               |          | DHCP Request                                                                         |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-4                                               |          | DHCP ACK                                                                             |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-5                                               |          | DNS Request                                                                          |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-6                                               |          | DNS SRV (KDC host name associated with the provisioning realm)                       |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-7                                               |          | DNS Request                                                                          |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-8                                               |          | DNS Response (KDC IP Address)                                                        |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-9                                               |          | AS Request                                                                           |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-9a                                              |          |                                                                                      |            |            |           |             |          |         |          | MTA FQDN Request |     |                        |        |
+| MTA-9b                                              |          |                                                                                      |            |            |           |             |          |         |          | MTA FQDN Reply   |     |                        |        |
+| MTA-10                                              |          | AS Reply                                                                             |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-11                                              |          | TGS Request                                                                          |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-12                                              |          | TGS Reply                                                                            |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-13                                              |          | AP Request                                                                           |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-14                                              |          | AP Reply                                                                             |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-15                                              |          | SNMP Inform                                                                          |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-16                                              |          | SNMP Get Request(s) for MTA device capabilities (optional/iterative)                 |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-17                                              |          | SNMP Get Response(s) containing MTA device capabilities (optional/iterative)         |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-18                                              |          |                                                                                      |            |            |           |             |          |         |          | MTA config file  |     |                        |        |
+| MTA-19                                              |          | SNMP Set with URL encoded file download access method (TFTP or HTTP) and filename    |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-20                                              |          | Resolve TFTP server FQDN                                                             |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-21                                              |          | TFTP server IP address                                                               |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-22                                              |          | Telephony config file request                                                        |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-23                                              |          | Telephony config file                                                                |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-24                                              |          | MTA sends telephony service provider SYSLOG a notification of provisioning completed |            |            |           |             |          |         |          |                  |     |                        |        |
+| MTA-25                                              |          | Notify completion of telephony provisioning (MTA MAC address, ESN, pass/fail)        |            |            |           |             |          |         |          |                  |     |                        |        |
+| SEC-1                                               |          | DNS Request                                                                          |            |            |           |             |          |         |          |                  |     |                        |        |
+| SEC-2                                               |          | DNS SRV (KDC host name associated with the telephony realm)                          |            |            |           |             |          |         |          |                  |     |                        |        |
+| SEC-3                                               |          | DNS Request                                                                          |            |            |           |             |          |         |          |                  |     |                        |        |
+| SEC-4                                               |          | DNS Response (MSO KDC IP Address)                                                    |            |            |           |             |          |         |          |                  |     |                        |        |
+| SEC-5                                               |          | AS Request (PKINIT) (MTA Device Cert, MTA Manufacturer Cert, MTA FQDN, Prov CMS ID)  |            |            |           |             |          |         |          |                  |     |                        |        |
+| SEC-5a                                              |          |                                                                                      |            |            |           |             |          |         |          | MTA FQDN Request |     |                        |        |
+| SEC-5b                                              |          |                                                                                      |            |            |           |             |          |         |          | MTA FQDN Reply   |     |                        |        |
+| SEC-6                                               |          | AS Reply (PKINIT) (TGT with MTA service provider FQDN)                               |            |            |           |             |          |         |          |                  |     |                        |        |
+| SEC-7                                               |          | TGS Request (CMS Kerberos ticket)                                                    |            |            |           |             |          |         |          |                  |     |                        |        |
+| SEC-8                                               |          | TGS Reply (CMS Kerberos ticket)                                                      |            |            |           |             |          |         |          |                  |     |                        |        |
+
+J.170\_F10
+
+Figure 10 – IPCablecom provisioning flows
+
+As part of the provisioning process, the MTA performs Kerberos key management (AS Request/AS Reply and AP Request/AP Reply, and optional TGS Request/TGS Reply).
+
+Table 20 describes the execution of the Kerberos key management step during MTA provisioning:
+
+**Table 20 – Kerberos key management during MTA provisioning**
+
+| Flow step                                                                   | Security requirement                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | Lifetime                                                                                | Step bypass permitted                                                                                                                                                                                                                                                                                                                                                                  |
+|-----------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| <i>MTA-9/MTA-10</i><br>AS Request/AS<br>Response (see 6.4.1)                | TGT ticket if using TGS<br>Request; Provisioning<br>Server Ticket if otherwise                                                                                                                                                                                                                                                                                                                                                                                                                                   | Max. 7 days                                                                             | This step <b>MUST NOT</b> be<br>performed if the MTA<br>already possesses a valid<br>ticket for the<br>Provisioning Server.                                                                                                                                                                                                                                                            |
+| <i>MTA-9a/MTA-9b</i> –<br>MTA FQDN<br>Request/MTA FQDN<br>Reply (see 6.4.7) | MTA FQDN Request and<br>Reply are protected using<br>Kerberos tickets                                                                                                                                                                                                                                                                                                                                                                                                                                            |                                                                                         | These steps will not<br>occur if MTA-9 is<br>skipped. Otherwise, this<br>step cannot be bypassed.                                                                                                                                                                                                                                                                                      |
+| <i>MTA-11/MTA 12</i><br>TGS Request/TGS<br>Response (see 6.4.4)             | Applies when a TGT is<br>used. Obtains a Provisioning<br>Server Ticket.                                                                                                                                                                                                                                                                                                                                                                                                                                          | Lifetime is set to<br>expire no later than<br>the expiration time<br>of the TGT ticket. | This step <b>MUST NOT</b> be<br>performed if the MTA<br>already possesses a valid<br>ticket for the<br>Provisioning Server.                                                                                                                                                                                                                                                            |
+| <i>MTA-13/MTA-14</i><br>AP Request/AP Reply<br>(see 6.5.2 and 6.5.4)        | Initial SNMPv3<br>authentication and privacy<br>keys for the MTA. The user<br>name for the MTA is<br>specified as "MTA-Prov-<br>xx:xx:xx:xx:xx:xx", where<br>xx:xx:xx:xx:xx:xx<br>represents the MAC address<br>of the MTA.<br>AP Req/AP Rep messages<br>do not specify the SNMPv3<br>key expiration time in the<br>protocol, but the SNMP<br>Manager may still set up<br>expiration time locally; after<br>the keys expire, the manager<br>can send a Wake Up<br>message to create a new set<br>of SNMPv3 keys. | Expiration is not<br>supported by<br>IP Cablecom.                                       | None. New SNMPv3<br>keys and User Ids are<br>created each time the<br>MTA is re-initialized. It<br>is assumed that SNMPv3<br>keys and User IDs are<br>not saved in NVRAM.<br>Also note that this step is<br>used for Engine ID<br>determination and<br>SNMPv3 time<br>synchronization – the<br>two sides exchange<br>initial values for<br>SNMPv3 boots and<br>engine time parameters. |
+
+An MTA **MUST** get a new ticket before performing Kerberized Key Management with a particular Application Server if the ticket(s) it currently possesses is not valid. A ticket would no longer be valid if the KDC REALM or Application Server FQDN changes, if the MTA's IP address has changed, or if the current time, adjusted by the time offset for that REALM or Application Server, does not fall within the ticket validity period.
+
+The PKINIT<sub>GP</sub> for the Provisioning Server's realm is specified in the MTA MIB inside the realm table. When the MTA implementation requests a TGT in an AS Request and when the MTA needs to obtain tickets for one or more CMSs in the same realm as the Provisioning Server, the PKINIT<sub>GP</sub> value specified in the MIB **MUST** be used to refresh the TGT. In all other cases, the AS Request for the TGT in the Provisioning Server's realm or for the Provisioning Server's ticket directly **MAY** be issued on demand.
+
+The TGS Grace Period is not specified for the key management between the MTA and the Provisioning Server. The TGS Request for the Provisioning Server's ticket **MAY** be issued on demand.
+
+### 7.1.1 Device provisioning
+
+Device provisioning occurs when an MTA device is inserted into the network. A provisioned MTA device that is not yet associated with a billing record MAY have minimal voice communications service available.
+
+Device provisioning involves the MTA making itself visible to the network, obtaining its IP configuration and downloading its configuration data.
+
+The IPCablecom architecture supports three provisioning flows:
+
+- Basic Flow;
+- Hybrid Flow;
+- Secure Flow.
+
+The Basic and Hybrid Flows are completely insecure flows (i.e., there are no mechanisms in the flows that would prevent a user from provisioning their own MTA). The Basic and Hybrid Flows also do not provide a means to secure the SNMP management interface on the MTA. Service providers that choose to deploy MTAs with one of these insecure flows must accept that there are security risks. For example, a Denial-of-Service attack could be mounted by sending SNMP TRAPs and INFORMs to the operator's management system. The management system would have to process them, even though they are unauthenticated. Unfortunately, the inclusion of these insecure flows also poses security risks for Service Providers that choose to deploy MTAs with the Secure Flow.
+
+MTAs that support the insecure flows may be provisioned by a user, even if the service provider is using the Secure Flows. Unauthorized provisioning of an MTA allows a user to provide their own configuration file. The MTA could then be used to communicate normally with a CMS. Alternatively, un-authorized provisioning of an MTA could be used to bypass service provider controls on secure software download (in the case of the S-MTA) and provide a software image that has some perceived value (such as a security vulnerability).
+
+With respect to the Secure Flow, support for SNMPv2c coexistence for network management operations also introduces vulnerabilities to service providers that use the Secure Flow (unauthenticated TRAPs and INFORMs could be sent). The best way to address these vulnerabilities is to disable SNMPv2c coexistence.
+
+Therefore it is recommended, as always, that service providers use multiple layers of security to ensure that their CMSs and back-office systems are protected against rogue MTAs.
+
+#### 7.1.1.1 Security services
+
+##### 7.1.1.1.1 MTA-DHCP server
+
+Authentication and Message Integrity is desirable on this interface, in order to prevent denial-of-service attacks that cause an MTA to be improperly configured. Securing DHCP is considered an operational issue to be evaluated by each network operator. It is possible to use access control through the local DHCP relay inside the local loop. IPsec can be used for security between the DHCP relay and the DHCP server.
+
+##### 7.1.1.1.2 MTA-SNMP manager
+
+This clause applies to all SNMPv3 messages between the MTA and an SNMPv3 Manager. Within the IPCablecom architecture, the Provisioning Server includes the SNMPv3 Manager function, although SNMPv3 traffic occurs both during and after the provisioning phase.
+
+*Authentication:* the identity of the MTA that is sending configuration parameters and faults to the SNMP manager must be authenticated, to prevent denial of service attacks. For example, the Provisioning Server may be tricked into continuously creating bogus configuration files or into creating a configuration file based on incorrect MTA capabilities that in effect disable that MTA.
+
+Also, during the provisioning sequence the MTA is told (via an SNMP Set) the parameters needed to find, authenticate and decrypt its configuration file. If this SNMP Set were forged, it would disrupt the MTA provisioning sequence.
+
+*Message Integrity:* required to prevent denial-of-service attacks at the OSS and at the MTA – see the above description of the denial-of-service attacks under authentication.
+
+*Confidentiality:* may be used to protect sensitive MTA configuration data. IPCablecom currently does not specify any such sensitive MTA parameters and so confidentiality is optional.
+
+*Access Control:* write access to the MTA configuration parameters must be allowed only to the authorized OSS users, to prevent denial of service/misconfiguration attacks. Read access can be enforced in conjunction with confidentiality, which is optional (see above on confidentiality).
+
+Note that DHCP is used to configure the MTA with the Kerberos realm name, which points it to a particular KDC. DHCP also configures the MTA with the location of the Provisioning Server. Since IPCablecom currently does not specify DHCP security, by faking DHCP responses it is possible to point MTAs to a wrong Provisioning Server and to a wrong KDC that permits security establishment with that Provisioning Server. (The MTA would only authenticate that wrong KDC if the CableLabs Service Provider Root CA signed the KDC certificate.) So, it is possible to bypass access control, but the attack has to be orchestrated by another MSO that had also been certified by IPCablecom.
+
+##### **7.1.1.1.3 MTA-Provisioning Server, via TFTP Server**
+
+*Authentication:* required to prevent denial-of-service attacks, that cause an MTA to be improperly configured.
+
+*Message integrity:* required to prevent denial-of-service attacks that cause an MTA to be either improperly configured or configured with old configuration data that was replayed.
+
+*Confidentiality:* optional; it is up to the Provisioning Server to decide whether or not to encrypt the file.
+
+*Access control:* not required at the TFTP Server. If needed, MTA configuration file is encrypted with the Provisioning Server-MTA shared key.
+
+*Non-repudiation:* is not required.
+
+#### **7.1.1.2 Cryptographic mechanisms**
+
+##### **7.1.1.2.1 Call flows MTA-15, 16, 17: MTA-SNMP Manager: SNMP Inform/Get Requests/Responses**
+
+All SNMP traffic between the MTA and the SNMP Manager in both directions is protected with SNMPv3 security per RFC 3414 during the Secure Provisioning process. IPCablecom requires that SNMPv3 message authentication is always turned on with privacy being optional (see 6.3). The only SNMPv3 encryption algorithm is currently DES-CBC. This is the limitation of the SNMPv3 IETF standard, although stronger encryption algorithms are desirable. See 6.3. for the list of SNMPv3 cryptographic algorithms supported by IPCablecom.
+
+##### 7.1.1.2.2 Call Flow MTA-18: Provisioning Server-TFTP Server: Create MTA Configuration file
+
+This clause describes the MTA Config file creation in the Secure Provisioning Flow. In this flow, the Provisioning Server builds a MTA device configuration file. This file MUST contain the following configuration info for each endpoint (port) in the MTA:
+
+- CMS name (FQDN format);
+- Kerberos realm for this CMS;
+- Telephony Service Provider Organization Name;
+- PKINIT Grace Period.
+
+This file MUST be authenticated and MAY be encrypted. If the configuration file is encrypted, then the SNMPv3 privacy MUST be used in order to transport the configuration file encryption key securely. Once the Provisioning Server builds the configuration file, it will perform the following steps:
+
+- 1) The provisioning Server decides to encrypt the file, it creates a configuration file encryption key and encrypts the file with this key. The encryption algorithm MUST be the same as the one that is used for SNMPv3 privacy. It then stores the key and the cipher. The file MUST be encrypted using the following procedure:
+  - a) prepend the file contents with a random byte sequence, called a confounder. The size of the confounder MUST be the same as the block size for the encryption algorithm. In the case of DES it is 8 bytes;
+  - b) append random padding to the result in a). The output of this step is of length that is a multiple of the block size for the encryption algorithm;
+  - c) encrypt the result in b) using IV = 0. The output of this step is the encrypted configuration file.
+- 2) It creates a SHA-1 hash of the configuration file and stores it. If the file was encrypted, the hash is taken over the encrypted file.
+- 3) It sends the following items to the MTA in the SNMP SET in the flow MTA-19.
+  - a) pktcMtaDevConfigKey, which is the configuration file encryption key MIB variable generated in step 1.
+  - b) pktcMtaDevConfigHash, which is the SHA-1 of the configuration file MIB variable generated in step 2.
+  - c) Name and location of the configuration file.
+
+Steps 1 and 2 MUST occur only when a configuration file is created or an existing file is modified. If the pktcMtaDevConfigKey is set, then the MTA MUST use this key to decrypt the configuration file. Otherwise, MTA MUST assume that the file is not encrypted. SNMPv3 provides authentication when the pktcMtaDevConfigHash is set and therefore the configuration file is authenticated indirectly via SNMPv3.
+
+In the event that SNMPv3 privacy is selected during the key management phase, but is using a different algorithm than the one that was selected to encrypt the configuration file (or the configuration file was previously in the clear), the configuration file MUST be re-encrypted and the TFTP server directory MUST be updated with the new file. Similarly, if the Provisioning Server decides not to encrypt the file this time, after it was previously encrypted, the TFTP server directory MUST be updated with the new file.
+
+MTA endpoints MAY also be configured for IP Telephony service while the MTA is operational. In that case the same information that is normally assigned to an endpoint in a configuration file MUST be assigned with SNMP Set commands.
+
+##### 7.1.1.2.3 Call flows MTA-19, 20 and 21: Establish TFTP server location
+
+This set of call flows is used to establish the IP address of the TFTP server from where the MTA will retrieve its configuration file. Although flow MTA-19 is authenticated via SNMPv3, MTA-20 and 21 are not authenticated.
+
+Flow MTA-21 allows for denial-of-service attacks, where the MTA is pointed to a wrong TFTP server (IP address). The MTA cannot be fooled in accepting the wrong configuration file since checking the hash of the file authenticates the file – this denial-of-service attack will result in failed MTA provisioning.
+
+The denial-of-service threats, where responses to DNS queries are forged, are currently not addressed by IPCablecom. It is mainly because DNS security (DNSSEC) is not yet available as a commercial product and would cause significant operational difficulty in the conversion of the DNS databases.
+
+##### 7.1.1.2.4 Call flows MTA-22, 23: MTA-TFTP Server: TFTP Get/Get Response
+
+The TFTP get request is not authenticated and thus anyone can request an MTA configuration file. This file does not contain any sensitive data and may be encrypted with the Provisioning Server-MTA shared key if the Provisioning Server chooses to. In this case no one except the MTA can make use of this file.
+
+This flow is open for a denial-of-service attack, where the TFTP server is made busy with useless TFTP get requests. This denial-of-service attack is not addressed at this time.
+
+The TFTP get response retrieves a configuration file from the TFTP server. The contents of the configuration file are listed in 7.1.1.2.2.
+
+##### 7.1.1.2.5 Security flows
+
+For each CMS specified in the pktcMtaDevCmsTable table with pktcMtaDevCmsIpsecCtrl value set to TRUE and assigned to a provisioned MTA endpoint, the MTA MUST perform the following security flows in Table 21 after the provisioning process and prior to any NCS message exchange. For each CMS specified in pktcMtaDevCmsTable with pktcMtaDevCmsIpsecCtrl set to FALSE, the MTA MUST NOT perform the following flows and MUST send and receive NCS messages without IPsec (i.e., NCS packets are sent in the "clear").
+
+**Table 21 – Post-MTA provisioning security flows**
+
+| Security flow                                                                  | Flow description                                                                                                                                                                                                                                                    | If step fails, proceed here |
+|--------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------|
+| Get Kerberos tickets associated with each CMS with which the MTA communicates. |                                                                                                                                                                                                                                                                     |                             |
+| SEC-1                                                                          | <i>DNS SRV Request</i><br>The MTA requests the Telephony KDC host name for the Kerberos realm.<br>This step MUST NOT be performed if the MTA already possesses a valid ticket for the CMS.                                                                          | SEC-1                       |
+| SEC-2                                                                          | <i>DNS SRV Reply</i><br>Returns the Telephony KDC host name associated with the provisioning realm. If the KDC's IP Address is included in the Reply, proceed to SEC-5.<br>This step MUST NOT be performed if the MTA already possesses a valid ticket for the CMS. | SEC-1                       |
+
+**Table 21 – Post-MTA provisioning security flows**
+
+| Security flow | Flow description                                                                                                                                                                                                                                                                                                                                | If step fails, proceed here                                                               |
+|---------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------|
+| SEC-3         | <i>DNS Request</i><br>The MTA now requests the IP Address of the Telephony KDC. This step MUST NOT be performed if the MTA already possesses a valid ticket for the CMS.                                                                                                                                                                        | SEC-1                                                                                     |
+| SEC-4         | <i>DNS Reply</i><br>The DNS Server returns the IP Address of the Telephony KDC. This step MUST NOT be performed if the MTA already possesses a valid ticket for the CMS.                                                                                                                                                                        | SEC-1                                                                                     |
+| SEC-5         | <i>AS Request</i><br>For each different CMS assigned to voice communications endpoints, the MTA requests a TGT or a Kerberos ticket for the CMS by sending a PKINIT REQUEST message to the KDC containing the MTA Device Certificate and the MTA FQDN. This step MUST NOT be performed if the MTA already possesses a valid ticket for the CMS. | Report alarm. Abort establishment of signalling security.                                 |
+| SEC-5a        | <i>MTA FQDN Request</i><br>The KDC requests the MTA's FQDN from the Provisioning Server.<br>This step will not occur if the MTA skips SEC-5.                                                                                                                                                                                                    |                                                                                           |
+| SEC-5b        | <i>MTA FQDN Reply</i><br>The Provisioning Server replies to the KDC request with the MTA's FQDN.<br>This step will not occur if the MTA skips SEC-5.                                                                                                                                                                                            |                                                                                           |
+| SEC-6         | <i>AS Reply</i><br>The KDC sends the MTA a PKINIT REPLY message containing the requested Kerberos ticket. This step MUST NOT be performed if the MTA already possesses a valid ticket for the CMS.                                                                                                                                              | Proceed to SEC-5 or abort signalling security depending upon error conditions.            |
+| SEC-7         | <i>TGS Request</i><br>In the case where the MTA obtained a TGT in SEC-6, it now obtains the Kerberos ticket for the TGS request message. This step MUST NOT be performed if the MTA already possesses a valid ticket for the CMS.                                                                                                               | Report alarm. Abort establishment of signalling security.                                 |
+| SEC-8         | <i>TGS Reply</i><br>Response to TGS Request containing the requested CMS Kerberos ticket. This step MUST NOT be performed if the MTA already possesses a valid ticket for the CMS.                                                                                                                                                              | Proceed here to SEC-7/SEC-5 or abort signalling security depending upon error conditions. |
+
+**Table 21 – Post-MTA provisioning security flows**
+
+| Security flow | Flow description                                                                                                                                                                                                                   | If step fails, proceed here                                                                     |
+|---------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------|
+| SEC-9         | <i>AP Request</i><br>The MTA requests a pair of IPsec simplex Security Associations (inbound and outbound) with the assigned CMS by sending the assigned CMS an AP REQUEST message containing the CMS Kerberos ticket.             | Report alarm. Abort establishment of signalling security.                                       |
+| SEC-10        | <i>AP Reply</i><br>The CMS establishes the Security Associations and then sends an AP REPLY message with the corresponding IPsec parameters. The MTA derives IPsec keys from the subkey in the AP Reply and establishes IPsec SAs. | Proceed here to SEC-9/SEC-7/SEC-5 or abort signalling security depending upon error conditions. |
+
+Several tables in the MTA MIB are used to control security flows SEC-1 through SEC-10 (see Table 21).
+
+The CMS table (pktcMtaDevCmsTable) and the realm table (pktcMtaDevRealmTable) are used for managing the MTA security signalling. The realm table defines the domains for the CMSs. The CMS table defines the CMSs within the domains. An endpoint is associated with one CMS at any given time. The following restrictions MUST be adhered to:
+
+- a) The realm table in the configuration file MUST at a minimum include an entry for the realm that is identified in DHCP option 122, suboption 6.
+- b) There MUST be a realm table entry for each CMS table entry. Multiple CMS table entries MAY utilize the same realm table entry.
+- c) Each MTA endpoint defined in the NCS endpoint table (pktcNcsEndPntConfigTable) MUST be configured with a CMS FQDN (pktcNcsEndPntConfigCallAgentId) that is also present in the CMS table (pktcMtaDevCmsFqdn).
+- d) All members of a CMS cluster defined by the same FQDN MUST use the same configuration for establishing security associations as defined in the pktcMtaDevCmsTable.
+- e) If NCS signalling selects a CMS (with an N: parameter selection) that is not defined by an entry in the CMS table, the same realm and CMS parameters, with the exception of the CMS FQDN and pktcMtaDevCmsIpsecCtrl, are used as defined in the current CMS table entry. The pktcMtaDevCmsIpsecCtrl flag for the new CMS MUST be set to TRUE.
+
+The use of the security-relevant MIB tables immediately following step MTA-25 is as follows:
+
+- 1) The MTA finds a list of CMSs with which it needs to establish IPsec SAs. This list MUST include every CMS that is assigned to a configured endpoint, as specified by the NCS MIB table pktcNcsEndPointConfigTable. This list of CMSs MUST include only CMSs that are listed in the pktcMtaDevCmsTable.
+- 2) For each CMS in the above list, the MTA MUST attempt to establish IPsec security associations as follows:
+  - a) Find the corresponding CMS table entry.
+  - b) If the MTA does not already possess a valid ticket for the specified CMS, use the pktcMtaDevCmsKerbRealmName parameter in the CMS table entry to index into the pktcMtaDevRealmTable. Then, using the parameters associated with that realm, perform steps SEC-1 through SEC-6 and optionally SEC-7 and SEC-8 in order to obtain the desired CMS ticket.
+
+- c) Perform IPsec key management according to flows SEC-9 and SEC-10. This step MAY occur at any time after step b above, but it must occur before any signalling messages are exchanged with that CMS.
+
+The CMS table entry contains various timing parameters used in steps SEC-9 and SEC-10. In the case of time-outs or other errors, the MTA may retry using the timing parameters specified in the CMS table entry.
+
+The above steps MUST also apply when an additional MTA endpoint is activated (see ITU-T Rec. J.167) or when an endpoint is configured (via SNMP sets) for a new CMS in the NCS MIB (see ITU-T Rec. J.166).
+
+- 3) Any time before an MTA endpoint sends a signalling message to a particular CMS, it MUST ensure that the respective security association is present. If the MTA is unable to establish IPsec SAs with a CMS that is associated with a configured endpoint (by the NCS MIB), it MUST set the NCS MIB variable `pktcNcsEndPntStatusError` to `noSecurityAssociation` (2).
+
+After the initial establishment of the IPsec security associations for CMSs, the MTA MIB is utilized in subsequent key management as follows:
+
+When the MTA receives a Wake Up message, it MUST respond with an AP Request when the corresponding CMS FQDN is found in the `pktcMtaDevCmsTable` and MUST NOT respond otherwise.
+
+Note that establishment of IPsec security associations due to a Wake Up does not result in any call signalling traffic between the MTA and the CMS.
+
+###### **7.1.1.2.5.1 Call flows SEC-5, 6: Get a Kerberos ticket for the CMS**
+
+The MTA uses PKINIT protocol to get a Kerberos ticket for the specified CMS (see 6.4.3). After the KDC receives a ticket request, it retrieves the MTA FQDN from the provisioning server so that it can verify the request before replying with a ticket. The Telephony KDC issues the Kerberos ticket for a group of one or more CMSs uniquely identified with the pair (Kerberos Realm, CMS Principal Name).
+
+In the event that different MTA ports are configured for a different group of CMSs, the MTA MUST obtain multiple Kerberos tickets by repeating these call flows for each CMS. Note that there is no requirement that the MTA obtain all the tickets from a single KDC.
+
+###### **7.1.1.2.5.2 Call flows SEC-7, 8, 9: Establish IPsec SAs with the CMS**
+
+The MTA uses the Kerberos ticket to establish a pair of simplex IPsec Security Associations with the given CMS. In the event that different MTA ports are configured with different CMS (FQDN) names, multiple pairs of SAs will be established (one set for each CMS).
+
+When a single Kerberos ticket is issued for clustered Call Agents, it is used to establish more than one pair of IPsec SAs.
+
+A CMS FQDN MAY translate into a list of multiple IP addresses, as would be the case with the NCS clustered Call Agents. In those cases, the MTA MUST initiate Kerberized key management with one of the IP addresses returned by the DNS Server. The MTA MAY also establish SAs with the additional CMS IP addresses.
+
+Additional IPsec SAs with the other IP addresses MAY be established later, as needed (e.g., the current CMS IP address does not respond).
+
+#### **7.1.1.3 Key management**
+
+##### **7.1.1.3.1 MTA-SNMP manager**
+
+Key management for the MTA-Provisioning SNMPv3 user MUST use the Kerberized key management protocol as it is specified in 6.5.4. The MTA and the Provisioning Server MUST support this key management protocol. Additional SNMPv3 users MAY be created with the standard SNMPv3 cloning method per RFC 3414 or with the same Kerberized key management protocol.
+
+In order to perform Kerberized key management, the MTA must first locate the KDC. It retrieves the provisioning realm name from DHCP and then uses a DNS SRV record lookup to find the KDC FQDN(s) based on the realm name (see 6.4.5.1). When there is more than one KDC (DNS SRV record) found, DNS assigns a priority (and possibly a weighting) to each one. The MTA will choose a KDC based on the DNS priority and weight labelling and will go through the list until it finds a KDC that is able to respond.
+
+##### **7.1.1.3.2 MTA-TFTP server**
+
+The optional encryption key for the MTA configuration file is passed to the MTA with an SNMP Set command (by the Provisioning Server) shown in the provisioning flow MTA-19. SNMPv3 security is utilized to provide message integrity and privacy. In the event that SNMPv3 privacy is not enabled, the MTA configuration file MUST NOT be encrypted and the file encryption key MUST NOT be passed to the MTA.
+
+The encryption algorithm used to encrypt the file MUST be the same as the one used for SNMPv3 privacy. The same file encryption key MAY be re-used on the same configuration file while the MTA configuration file contents are unchanged. However, if the MTA configuration file changes or if a different encryption algorithm is selected for SNMPv3 privacy, the Provisioning Server MUST generate a new encryption key, MUST re-encrypt the configuration file and MUST update the TFTP server with the re-encrypted file.
+
+#### **7.1.1.4 MTA embedded keys**
+
+The MTA device MUST be manufactured with a public/private RSA key pair and an X.509 device certificate that MUST be different from the BPI+ device certificate.
+
+#### **7.1.1.5 Summary security profile matrix – Device provisioning**
+
+The following matrix in Table 22 applies only to the Secure Provisioning Flow and SNMPv3.
+
+**Table 22 – Security profile matrix – MTA device provisioning**
+
+|                     | SNMP                                                                                                                                                               | TFTP (MTA-TFTP server)                                                                                                                                                                                             |
+|---------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Authentication      | Yes                                                                                                                                                                | Yes: authentication of source of configuration data.                                                                                                                                                               |
+| Access control      | Yes: write access to MTA configuration is limited to authorized SNMP users.<br>Read access can also be limited to the valid users when confidentiality is enabled. | Yes: write access to the TFTP server must be limited to the Provisioning Server but is out of scope for IPCablecom. Read access can be optionally indirectly enabled when the MTA configuration file is encrypted. |
+| Integrity           | Yes                                                                                                                                                                | Yes                                                                                                                                                                                                                |
+| Confidentiality     | Optional                                                                                                                                                           | Optional (of MTA configuration information during the TFTP-get).                                                                                                                                                   |
+| Non-repudiation     | No                                                                                                                                                                 | No                                                                                                                                                                                                                 |
+| Security mechanisms | SNMPv3 authentication and privacy. Kerberized key management protocol defined by IPCablecom.                                                                       | Hash of the MTA configuration file is sent to the MTA over SNMPv3, providing file authentication. When the file is encrypted, the key is also sent to the MTA over SNMPv3 (with SNMPv3 encryption turned on).      |
+
+### 7.1.2 Subscriber enrolment
+
+The subscriber enrolment process establishes a permanent customer billing account that uniquely identifies the MTA to the CMS via the endpoint ID, which contains the MTA's FQDN. The billing account is also used to identify the services subscribed to by the customer for the MTA.
+
+Subscriber enrolment MAY occur in-band or out-of-band. The actual specification of the subscriber enrolment process is out of scope for IPCablecom and may be different for each Service Provider. The device provisioning procedure described in the previous clause allows the MTA to establish IPsec Security Associations with one or more Call Agents, regardless of whether or not the corresponding subscriber had been enrolled.
+
+As a result, when subscriber enrolment is performed in-band, a communication to a Customer Service Record (CSR) (or to an automated subscriber enrolment system) is protected using the same security mechanisms that are used to secure all other voice communication.
+
+During each communication set-up (protected with IPsec ESP), the CMS MUST check the identity of an MTA against its authorization database to validate which voice communications services are permitted. If that MTA does not yet correspond to an enrolled subscriber, it will be restricted to permitting a customer to contact the service provider to establish service ("customer enrolment"). Some additional services, such as communications with emergency response organizations (e.g., 911), may also be permitted in this case. Since in-band customer enrolment is based on standard security provided for call signalling and media streams, no further details are provided in this clause. Refer to 7.6 and 6.6 on media streams.
+
+## 7.2 Quality of Service (QoS) signalling
+
+### 7.2.1 Dynamic Quality of Service (DQoS)
+
+#### 7.2.1.1 Reference architecture for embedded MTAs
+
+![Diagram of QoS Signalling interfaces in the IPCablecom network. The diagram shows a symmetrical architecture with two MTAs (yellow) at the top, each connected to a CM (grey). Each CM is connected to a CMTS (grey), which is in turn connected to a Record Keeping Server (yellow). The two Record Keeping Servers are connected to each other. The two CMTSs are connected to two CMS/Gate Controllers (yellow), which are also connected to each other. The two CMS/Gate Controllers are connected to the two MTAs. Various packet types are labeled: pkt-q1 (MTA to CM), pkt-q2 (CM to CMTS), pkt-q3 (MTA to CMS/Gate Controller), pkt-q4 (CM to CMS/Gate Controller), pkt-q5 (CMTS to CMS/Gate Controller), pkt-q6 (CMTS to Record Keeping Server), and pkt-q7 (CMS/Gate Controller to CMS/Gate Controller). A small database icon is shown next to each CM.](a963ca41bde1669b18a4b783616f228b_img.jpg)
+
+Diagram of QoS Signalling interfaces in the IPCablecom network. The diagram shows a symmetrical architecture with two MTAs (yellow) at the top, each connected to a CM (grey). Each CM is connected to a CMTS (grey), which is in turn connected to a Record Keeping Server (yellow). The two Record Keeping Servers are connected to each other. The two CMTSs are connected to two CMS/Gate Controllers (yellow), which are also connected to each other. The two CMS/Gate Controllers are connected to the two MTAs. Various packet types are labeled: pkt-q1 (MTA to CM), pkt-q2 (CM to CMTS), pkt-q3 (MTA to CMS/Gate Controller), pkt-q4 (CM to CMS/Gate Controller), pkt-q5 (CMTS to CMS/Gate Controller), pkt-q6 (CMTS to Record Keeping Server), and pkt-q7 (CMS/Gate Controller to CMS/Gate Controller). A small database icon is shown next to each CM.
+
+J.170\_F11
+
+Figure 11 – QoS Signalling interfaces in the IPCablecom network
+
+#### 7.2.1.2 Security services
+
+##### 7.2.1.2.1 CM-CMTS J.112 QoS messages
+
+Refer to ITU-T Rec. J.112.
+
+##### 7.2.1.2.2 Gate Controller – CMTS COPS messages
+
+*Authentication, access control and message integrity:* required to prevent QoS theft and denial-of-service attacks.
+
+*Confidentiality:* required to keep customer information private.
+
+#### 7.2.1.3 Cryptographic mechanisms
+
+##### 7.2.1.3.1 CM-CMTS J.112 QoS messages
+
+The J.112 QoS messages are specified in the radio-frequency interface (RFI) specification in ITU-T Rec. J.112.
+
+###### 7.2.1.3.1.1 QoS service flow
+
+A service flow is a J.112 MAC-layer transport service that provides unidirectional transport of packets either to upstream packets transmitted by the CM or to downstream packets transmitted by the CMTS. A service flow is characterized by a set of QoS Parameters such as latency, jitter, and throughput assurances. In order to standardize operation between the CM and CMTS, these attributes include details of how the CM requests mini-slots and the expected behavior of the CMTS upstream scheduler.
+
+ITU-T J.112 defines a Classifier, which consists of some packet matching criteria (IP source address, for example), a classifier priority, and a reference to a service flow. If a packet matches the specified packet matching criteria, it is then delivered on the referenced service flow.
+
+Downstream Classifiers are applied by the CMTS to packets it is transmitting, and Upstream Classifiers are applied at the CM and may be applied at the CMTS to police the classification of upstream packets.
+
+The network can be vulnerable to IP packet attacks; i.e., attacks stemming from an attacker using another MTA's IP source address and flooding the network with the packets intended for another MTA's destination address. A CMTS controlling downstream service flows will limit an MTA's downstream bandwidth according to QoS allocations. If the CMTS is flooded from the backbone network with extra packets intended for one of its MTAs, packets for that MTA may be dropped to limit the downstream packet rate to its QoS allocation. The influx of the attacker's packets may result in the dropping of good packets intended for the destination MTA.
+
+To thwart this type of network attack, access to the backbone network should be controlled at the entry point. This can be accomplished using a variety of QoS classifiers, but is most effective when the packet source is verified by its source IP address. This will limit the ability of a rogue source to flood the network with unauthorized IP packets.
+
+To address J.112 CMTS accesses to the network, the CMTS SHOULD apply upstream classifiers to police upstream packets from its network, including the verification of the source IP address.
+
+For more information regarding the use of packet classifiers, refer to the J.112 CMTS-CMS Gate Coordination Messages (over UDP).
+
+##### 7.2.1.3.2 Gate Controller – CMTS COPS messages
+
+To download a QoS policy for a particular communications connection, the Gate Controller function in the CMS MUST send COPS messages to the CMTS. These COPS messages MUST be both authenticated and encrypted with IPsec ESP. Refer to 6.1 on the details of how IPsec ESP is used within IPCablecom and for the list of available ciphersuites.
+
+#### 7.2.1.4 Key management
+
+##### 7.2.1.4.1 Gate Controller – CMTS COPS messages
+
+Key management for this COPS interface is either IKE or Kerberos. Implementations MUST support IKE with pre-shared keys. Implementations MAY support IKE with X.509 certificates and they MAY support Kerberos using symmetric keys. For more information on the IPCablecom use of IKE, refer to 6.2.2. For more information on the IPCablecom use of Kerberos with symmetric keys, refer to 6.4.3 and 6.5.
+
+When the Gate Controller detects a failure of all COPS connections associated with a particular outgoing IPsec SA, it MUST delete all associated SAs (IKE and IPsec SAs if IKE is used as the Key management protocol or only IPsec SAs if Kerberos is used as the Key management protocol).
+
+Subsequently, every N times ( $1 \leq N \leq 10$ ) that the Gate Controller tries to recover the connection, the SAs MUST be removed.
+
+##### 7.2.1.4.2 Security profile matrix summary
+
+**Table 23 – Security profile matrix – DQoS**
+
+|                     | <b>COPS<br/>(CMTS-CMS)</b>                                      |
+|---------------------|-----------------------------------------------------------------|
+| Authentication      | Yes                                                             |
+| Access control      | Yes                                                             |
+| Integrity           | Yes                                                             |
+| Confidentiality     | Yes                                                             |
+| Non-repudiation     | No                                                              |
+| Security mechanisms | IPsec with encryption and message integrity.<br>IKE or Kerberos |
+
+## 7.3 Billing system interfaces
+
+### 7.3.1 Security services
+
+#### 7.3.1.1 CMS-RKS interface
+
+*Authentication, access control and message integrity:* required to prevent service theft and denial-of-service attacks. Want to ensure that the billing events reported to the RKS are not falsified.
+
+*Confidentiality:* required to protect subscriber information and communication patterns.
+
+#### 7.3.1.2 CMTS-RKS interface
+
+*Authentication, access control and message integrity:* required to prevent service theft and denial-of-service attacks. Want to ensure that the billing events reported to the RKS are not falsified.
+
+*Confidentiality:* required to protect subscriber information and communication patterns. Also, effective QoS information and network performance is kept secret from competitors.
+
+#### 7.3.1.3 MGC-RKS interface
+
+*Authentication, access control and message integrity:* required to prevent service theft and denial-of-service attacks. Want to ensure that the billing events reported to the RKS are not falsified.
+
+*Confidentiality:* required to protect subscriber information and communication patterns.
+
+### 7.3.2 Cryptographic mechanisms
+
+Both message integrity and privacy MUST be provided by IPsec ESP, using any of the ciphersuites that are listed in 6.1.2.
+
+RADIUS itself defines MD5-based keyed MAC for message integrity at the application layer. And, there does not appear to be a way to turn off this additional integrity check at the application layer. For IPCablecom, the key for this RADIUS MAC MUST always be hardcoded to the value of 16 ASCII 0s. This, in effect, turns the RADIUS keyed MAC into an MD5 hash that can be used to protect against transmission errors but does not provide message integrity. No key management is needed for RADIUS MACs.
+
+Billing event messages contain an 8-octet binary Element ID of the CMS, CMTS or the MGC. The RKS MUST verify each billing event by ensuring that the specified Element ID correctly corresponds to the IP address. This check is done via a lookup into a map of IP addresses to Element IDs. Refer to 7.3.3 on how this map is maintained. A combined element (such as a combined CMS/MGC) MAY use the same IP address and Security Association to convey Event Messages from both elements. Additionally, both elements may use the same Element ID. Refer to 7.3.3.1 for information on how to maintain a map of multiple elements and Element IDs.
+
+#### 7.3.2.1 RADIUS server chaining
+
+RADIUS servers may be chained. This means that when the local RADIUS server that is directly talking to the CMS or CMTS client is not able to process a message, it forwards it to the next server in the chain.
+
+IPCablecom specifies security mechanisms only on the links to the local RADIUS server. IPCablecom also requires authentication, access control, message integrity and privacy on the interfaces between the chained RADIUS servers, but the corresponding specifications are outside of the scope of IPCablecom.
+
+Key management (in the following clause) applies to the local RADIUS server/RKS only.
+
+### **7.3.3 Key management**
+
+#### **7.3.3.1 CMS-RKS interface**
+
+The CMS and the RKS MUST negotiate a shared secret (CMS-RKS Secret) using IKE or Kerberos with symmetric keys (implementations MUST support IKE with pre-shared keys; they MAY support IKE with X.509 certificates and they MAY support Kerberos using symmetric keys). For more information on the IPCablecom use of IKE, refer to 6.2.2. For more information on the IPCablecom use of Kerberos with symmetric keys, refer to 6.4.3 and 6.5.
+
+The key management protocol MUST run asynchronous to the billing event generation and will guarantee that there is always a valid, non-expired CMS-RKS Secret.
+
+An RKS MUST maintain a mapping between an IP address and an Element ID for each host with which it has IPsec Security Associations. How this mapping is created depends on the IPsec key management protocol:
+
+- 1) IKE with Pre-Shared Keys. One way to implement this mapping is to provide a local database of which Element ID(s) are associated with the source IP address.
+- 2) IKE with Certificates. As specified in 8.2.3.4.3, a certificate of a server that sends billing event messages to an RKS contains its Element ID(s) in the CN attribute of the distinguished name. During IKE phase 1, the RKS MUST save a mapping between the IP address and its Element ID(s) that is contained in the certificate.
+- 3) Kerberized Key Management. As specified in 6.4.5.5, a principal name of each server that reports billing event messages to the RKS includes its Element ID(s). After an RKS receives and validates an AP Request message, it MUST save a mapping between the IP address and its Element ID(s) that is contained in the principal name.
+
+When an event message arrives at the RKS, the RKS MUST retrieve a source IP address based on the Element ID, using the mapping established during key management. The RKS MUST ensure that this address is the same as the source IP address in the IP packet header.
+
+Later, when a billing event arrives at the RKS, it MUST be able to query the database of IPsec Security Associations and retrieve a source IP address, based on the Element ID. The RKS MUST ensure that it is the same as the source IP address in the IP packet header.
+
+#### **7.3.3.2 CMTS-RKS interface**
+
+CMTS and RKS MUST negotiate a shared secret (CMTS-RKS Secret) using IKE or Kerberos (implementations MUST support IKE with pre-shared keys; they MAY support IKE with X.509 certificates and they MAY support Kerberos using symmetric keys). For more information on the IPCablecom use of IKE, refer to 6.2.2. For more information on the IPCablecom use of Kerberos with symmetric keys, refer to 6.4.3 and 6.5.
+
+The key management protocol MUST be running asynchronous to the billing event generation and will guarantee that there is always a valid, non-expired CMTS-RKS Secret.
+
+An RKS maintains a mapping between an IP address and an Element ID for each host with which it has IPsec Security Associations, as specified in 7.3.3.1. This includes the CMTS.
+
+When a billing event arrives at the RKS, it MUST retrieve a source IP address, based on the Element ID using the mapping established during key management. The RKS MUST ensure that it is the same as the source IP address in the IP packet header.
+
+#### **7.3.3.3 MGC-RKS interface**
+
+MGC and RKS MUST negotiate a shared secret (MGC-RKS Secret) using IKE or Kerberos (implementations MUST support IKE with pre-shared keys; they MAY support IKE with X.509 certificates and they MAY support Kerberos using pre-shared keys). For more information on the
+
+IPCablecom use of IKE, refer to 6.2.2. For more information on the IPCablecom use of Kerberos with symmetric keys, refer to 6.4.3 and 6.5.
+
+The key management protocol MUST be running asynchronous to the billing event generation and will guarantee that there is always a valid, non-expired MGC-RKS Secret.
+
+An RKS maintains a mapping between an IP address and an Element ID for each host with which it has IPsec Security Associations, as specified in 7.3.3.1. This includes the MGC.
+
+When an event arrives at the RKS, it MUST retrieve a source IP address, based on the Element ID based on the mapping established during key management. The RKS MUST ensure that it is the same as the source IP address in the IP packet header.
+
+### 7.3.4 Billing system summary security profile matrix
+
+Table 24 – Security profile matrix – RADIUS
+
+|                     | RADIUS Accounting<br>(CMS-RADIUS<br>Server/RKS)                                                  | RADIUS Accounting<br>(CMTS-RADIUS<br>Server/RKS)                                                 | RADIUS Accounting<br>(MGC-RADIUS<br>Server/RKS)                                                  |
+|---------------------|--------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------|
+| Authentication      | Yes                                                                                              | Yes                                                                                              | Yes                                                                                              |
+| Access control      | Yes                                                                                              | Yes                                                                                              | Yes                                                                                              |
+| Integrity           | Yes                                                                                              | Yes                                                                                              | Yes                                                                                              |
+| Confidentiality     | Yes                                                                                              | Yes                                                                                              | Yes                                                                                              |
+| Non-repudiation     | No                                                                                               | No                                                                                               | No                                                                                               |
+| Security mechanisms | IPsec ESP with encryption and message integrity enabled.<br>Key management using IKE or Kerberos | IPsec ESP with encryption and message integrity enabled.<br>Key management using IKE or Kerberos | IPsec ESP with encryption and message integrity enabled.<br>Key management using IKE or Kerberos |
+
+## 7.4 Call signalling
+
+### 7.4.1 Network Call Signalling (NCS)
+
+#### 7.4.1.1 Reference architecture
+
+Figure 12 shows the network components and the various interfaces to be discussed in this clause.
+
+![Figure 12 – NCS reference architecture diagram showing CMS a, CMS b (Call agent cluster), Remote CMS, MTA, and Remote MTA connected via various interfaces labeled pkt-s5: NCS, pkt-s16: CMSS, pkt-s3: RTP, and pkt-s4: RTCP.](f087d3f5d298b3b1634d13ff17879e41_img.jpg)
+
+The diagram illustrates the NCS reference architecture. On the left, a box labeled 'CMS a' is connected to a box labeled 'MTA' via an interface labeled 'pkt-s5: NCS'. In the center, a box labeled 'CMS b (Call agent cluster)' contains three smaller boxes and is also connected to the 'MTA' via the 'pkt-s5: NCS' interface. To the right, a box labeled 'Remote CMS' is connected to the 'CMS b' box via an interface labeled 'pkt-s16: CMSS'. Below the 'Remote CMS' box is a box labeled 'Remote MTA'. The 'MTA' box is connected to the 'Remote MTA' box via two interfaces labeled 'pkt-s3: RTP' and 'pkt-s4: RTCP'. The label 'J.170\_F12' is located at the bottom right of the diagram.
+
+Figure 12 – NCS reference architecture diagram showing CMS a, CMS b (Call agent cluster), Remote CMS, MTA, and Remote MTA connected via various interfaces labeled pkt-s5: NCS, pkt-s16: CMSS, pkt-s3: RTP, and pkt-s4: RTCP.
+
+Figure 12 – NCS reference architecture
+
+Figure 12 shows a CMS containing a cluster of Call Agents, which are identifiable by one CMS FQDN. It also shows, even though this is not a likely scenario in early deployments, that different CMSs could potentially manage different endpoints in a single MTA.
+
+The security aspects of interfaces pkt-s3 and pkt-s4 (RTP bearer channel and RTCP) are described in 6.6. The protocol interface pkt-s16 (CMS to CMS) is SIP, with IPCablecom extensions, as specified in ITU-T Rec. J.178.
+
+When a call is made between two endpoints in different zones, the call signalling has to traverse the path between two different CMSs. The signalling protocol between CMSs is SIP with IPCablecom specific extensions. See ITU-T Rec. J.178 for more details. Initially, the initiating CMS may not have a direct signalling path to a terminating CMS. The call routing table of the initiating CMS may point it to an intermediate SIP proxy. That SIP proxy, in turn, may point to another SIP proxy. In general, we make no assumptions about the number of SIP proxies in the signalling path between the CMSs. Once the two CMSs have discovered each other's location, they have the option to continue SIP signalling directly between each other. The SIP proxies that route traffic between domains are called Exterior Border Proxies (EBPs). EBPs enforce access control on all signalling messages routed between domains. They also provide application level security on sensitive information contained within SIP messages. While not depicted in Figure 12, CMSS may also be used between a CMS and an MGC.
+
+As SIP proxies and CMSs may be in different PacketCable domains (and consequently different trust domains), there must be a signalling path and trust relationship between two domains, before any direct SIP signalling can take place. IPCablecom Server certificates are used for TLS mutual authentication in CMSS and provide the trust infrastructure for SIP signalling. A CMS or EBP may be configured to trust only specific Service Provider CA certificates and/or FQDNs (i.e., access list) of external CMSs and EBPs. Generally, trust between different Service Provider domains is provided by the EBPs.
+
+#### 7.4.1.2 Security services
+
+The same set of requirements applies to both CMS-MTA and CMS-CMS signalling interfaces.
+
+*Authentication:* Signalling messages should be authenticated in order to prevent a third party masquerading as either an authorized MTA, CMS, MGC or SIP Proxy.
+
+*Confidentiality:* NCS messages carry dialled numbers and other customer information, which must not be disclosed to a third party. Thus, confidentiality of signalling messages should be required. The signalling messages carry media stream keying material that must be kept private on each signalling hop, and should also be kept private end-to-end between the initiating and target CMSs, to avoid exposure at SIP signalling proxies. There is no standard well-supported mechanism to support end-to-end privacy of keying material, however, so only hop-by-hop confidentiality is supported in IPCablecom.
+
+*Message integrity:* This should be assured in order to prevent tampering with signalling messages – e.g., changing the dialled numbers.
+
+*Access control:* Services enabled by the NCS signalling should be made available only to authorized users – thus, access control is required at the CMS.
+
+#### 7.4.1.3 Cryptographic mechanisms
+
+IPsec ESP MUST be used to secure the NCS signalling between the CMS and MTA. IPsec keys MUST be derived using the mechanism described in 6.5.3.1.
+
+TLS MUST be used to secure the SIP signalling (CMSS) between CMSs and between CMSs and SIP proxies (EBPs).
+
+The first SIP signalling round trip between the initiating and target CMSs may transit through any number of intermediate SIP signalling proxies. Since TLS is applied separately on each signalling hop, the contents of the SIP signalling message is decrypted and re-encrypted at each SIP signalling proxy. The full contents of the SIP signalling message, including media stream keying material, are available in the clear at each intermediate SIP signalling proxy.
+
+##### **7.4.1.3.1 MTA-CMS interface**
+
+Each signalling message coming from the MTA and containing the MTA domain name (included in the NCS endpoint ID field) must be authenticated by the CMS. This domain name is an application-level NCS identifier that will be used by the Call Agent to associate the communication with a paying subscriber. In order to perform this authentication, the CMS MUST maintain an IP address to FQDN map for each MTA IP address that has a current SA. This map MUST be built during the key management process described in the following clause and does not need to reside in permanent storage.
+
+##### **7.4.1.3.2 CMS-CMS, CMS-MGC, CMS-SIP Proxy and SIP Proxy-SIP Proxy interfaces**
+
+When a CMS, MGC or a SIP Proxy receives a SIP signalling message, it SHOULD map the source IP address to the identity (FQDN) of the CMS or SIP Proxy and to the local policy associated with that FQDN. This lookup would utilize an IP address FQDN map for all MGCs and SIP Proxies that have current TLS sessions with this host. This map is built during key management described in the following clause and does not need to reside in permanent storage.
+
+#### **7.4.1.4 Key management**
+
+##### **7.4.1.4.1 MTA-CMS key management**
+
+The MTA MUST use Kerberos with PKINIT to obtain a CMS service ticket (see 6.4.3). The MTA SHOULD first obtain a TGT (Ticket Granting Ticket) via the AS Request/AS Reply exchange with the KDC (authenticated with PKINIT). In the case that the MTA obtained a TGT, it performs a TGS Request/TGS Reply exchange to obtain the CMS service ticket (see 6.4.4).
+
+After the MTA has obtained a CMS ticket, it MUST execute a Kerberized key management protocol (that utilizes the CMS ticket) with the CMS to create SAs for the pkt-s10 interface. This Kerberized key management protocol is specified in 6.5. Clause 6.5 also describes the mechanism to be deployed to handle timed-out IPsec keys and Kerberos tickets. The mechanism for transparently handling key switch-over from one key lifetime to another key lifetime is also defined.
+
+The key distribution and time-out mechanism is not linked to any specific NCS message. Rather, the MTA will obtain the Kerberos ticket from the KDC when started and will refresh it based on the time-out parameter. Similarly, the MTA will obtain the sub-key (and thus IPsec ESP keys) based on the IPsec time-out parameters. In addition, when the IPsec ESP keys are timed out and the MTA needs to transmit data to the CMS, it will perform key management with the CMS and obtain the new keys. It is also possible for the IPsec SAs to expire at the CMS while it has data to send to the MTA. In this case, clause 6.5.3.5.3 describes the technique for the CMS to initiate key management and establish new security associations.
+
+###### **7.4.1.4.1.1 Call Agent clustering**
+
+At the time that the CMS receives a Kerberos ticket for establishing an IPsec SA, it MUST extract the MTA FQDN from the MTA principal name in the ticket and map it to the IP address. This map is later used to authenticate the MTA endpoint ID in the NCS signalling messages.
+
+In the case a CMS, or an application server, is constructed as a cluster of Call Agents with different IP addresses, all Call Agents should share the same service key for decrypting a Kerberos ticket. Thus, the MTA will need to execute a single PKINIT Request/Reply sequence with the KDC and
+
+multiple AP Request/Reply sequences for each Call Agent in the cluster. The Kerberos messages are specified in 6.4.4.
+
+Optimized key management is specified for the case when, in the middle of a communication, a clustered Call Agent sends a message to an MTA from a new IP address, where it does not yet have an IPsec SA with that MTA (see 6.5.2.1).
+
+In this optimized approach, the CMS sends a Rekey message instead of the Wake Up. This Rekey message is authenticated with a SHA-1 HMAC, using a Server Authentication Key, derived from a session key used to encrypt the last AP Reply sent from the same CMS (or another CMS with the same Kerberos Principal Name).
+
+Additionally, the Rekey message includes IPsec parameters, to avoid the need for the AP Reply message. The MTA responds with a different version of the AP Request that includes the MTA-CMS Secret, normally sent by the CMS in the AP Reply. As a result, after the MTA responds with the AP Request, a new IPsec SA can be established with no further messages. The total price for establishing a new SA with this optimized approach is a single round-trip time. This is illustrated in Figure 13.
+
+![Sequence diagram illustrating key management for NCS clusters. The diagram shows interactions between an MTA and a Call Agent cluster containing nodes IP1, IP2, and IP3. A Server Authentication Key K_SRA is shared across the cluster. The sequence of messages is: 1) AP Request from MTA to IP1; 2) AP Reply from IP1 to MTA (includes K_SRA); 3) RSIP (NCS over IPsec) from IP1 to MTA; 4) Rekey + new IPsec SA params + HMAC from IP3 to MTA; 5) AP Request from MTA to IP3 (includes MTA-CMS Secret); 6) NCS Signalling message (over IPsec) from IP3 to MTA. A note indicates that both MTA and CMS (at IP3) generate IPsec keys needed to establish security association SA3.](af90aabfe3c8c65617da060d82bf99c5_img.jpg)
+
+```
+
+sequenceDiagram
+    participant MTA
+    subgraph Call Agent cluster
+        IP1[IP1]
+        IP2[IP2]
+        IP3[IP3]
+    end
+    Note right of Call Agent cluster: Server Authentication Key KSRA shared across the cluster
+
+    MTA->>IP1: 1) AP Request
+    IP1-->>MTA: 2) AP Reply (includes KSRA)
+    IP1-->>MTA: 3) RSIP (NCS over IPsec)
+    IP3-->>MTA: 4) Rekey + new IPsec SA params + HMAC
+    MTA->>IP3: 5) AP Request (includes MTA-CMS Secret)
+    Note over MTA, IP3: Both MTA and CMS (at IP3) generate IPsec keys needed to establish security association SA3.
+    IP3-->>MTA: 6) NCS Signalling message (over IPsec)
+
+```
+
+Sequence diagram illustrating key management for NCS clusters. The diagram shows interactions between an MTA and a Call Agent cluster containing nodes IP1, IP2, and IP3. A Server Authentication Key K\_SRA is shared across the cluster. The sequence of messages is: 1) AP Request from MTA to IP1; 2) AP Reply from IP1 to MTA (includes K\_SRA); 3) RSIP (NCS over IPsec) from IP1 to MTA; 4) Rekey + new IPsec SA params + HMAC from IP3 to MTA; 5) AP Request from MTA to IP3 (includes MTA-CMS Secret); 6) NCS Signalling message (over IPsec) from IP3 to MTA. A note indicates that both MTA and CMS (at IP3) generate IPsec keys needed to establish security association SA3.
+
+**Figure 13 – Key management for NCS clusters**
+
+In Figure 13, an NCS clustered Call Agent suddenly decides to send an NCS message from a new IP address that did not previously have any SA established with that MTA.
+
+The first security association  $SA_1$  with CMS at  $IP_1$  was established with a basic AP Request/AP Reply exchange. HMAC key  $K_{SRA}$  for authenticating Rekey message from the CMS was derived from the session key used to encrypt the AP Reply (as shown in steps 1 through 3 in Figure 13).
+
+When a new SA<sub>3</sub> needs to be established between the MTA and CMS at IP<sub>3</sub>, the key management is as follows in steps 4 and 5 in Figure 13:
+
+- 4) The CMS at IP<sub>3</sub> sends a Rekey message, similar in functionality to the Wake Up message, but with a significantly different content. It contains:
+  - IPsec parameters (also found in the AP Reply): SPI, selected ciphersuite, SA lifetime, grace period, and re-establish flag. The purpose of adding these IPsec parameters to Rekey is to eliminate the need for the subsequent AP Reply message.
+  - SHA-1 HMAC using K<sub>SRA</sub>.
+- 5) AP Request that includes the MTA-CMS secret, normally sent in the AP Reply message. This is a legal Kerberos mode, where the key is contained in the AP Request and AP Reply is not used at all.
+
+For more details, refer to 6.5.3.
+
+###### **7.4.1.4.1.2 MTA controlled by multiple CMSs**
+
+In the case a single MTA is controlled by multiple CMSs and each CMS is associated with a different Kerberos realm, the MTA will need to execute multiple PKINIT Request/Reply exchanges with the KDC, one for each realm, optionally followed by a TGS Request/Reply exchange. Then, an MTA would execute multiple AP Request/Reply exchanges in order to create the security association with the individual CMSs.
+
+###### **7.4.1.4.1.3 Transferring from one CMS to another via NCS signalling**
+
+When control of an MTA endpoint is transferred from one CMS to another via NCS signalling, the following steps are taken:
+
+- 1) The new CMS might not have been included in the CMS table. In that case, the corresponding table entry MUST be locally created. Refer to 7.1.1.2.5 for instructions on how to create the new CMS table entry.
+- 2) If the MTA does not already have IPsec SAs established with this CMS (e.g., via an earlier Wake Up), it MUST attempt to establish them at this time.
+- 3) If the MTA now possesses valid IPsec security associations with the new CMS, the NCS signalling software is notified and the security association can be utilized. Further signalling traffic for this affected endpoint related to the prior CMS security association MUST NOT be sent.
+
+##### **7.4.1.4.2 CMS-CMS, CMS-MGC, CMS-SIP Proxy, SIP Proxy-SIP Proxy key management**
+
+When a CMS MGC, or a SIP Proxy has data to send to another CMS, MGC, or SIP Proxy and does not already have a TLS session with that host, it MUST first establish a TLS session with the other CMS, MGC, or SIP Proxy (see 6.9).
+
+A CMS or a SIP Proxy SHOULD create TLS sessions ahead of time (before they are needed) whenever possible and maintain persistent connections.
+
+###### **7.4.1.4.2.1 Example of inter-domain Call Set-up with TLS sessions**
+
+Figure 14 depicts a typical SIP signalling flow for an inter-domain call set-up in which EBPs are used (refer to ITU-T Rec. J.178 for further details on CMSS call flows). It illustrates several points in the End-End call set-up where different TLS sessions and TCP connections may be required and also emphasizes the importance of connection persistence and re-use to minimize TCP connection and TLS session establishment during the call set-up (i.e., in order to minimize performance impacts and call set-up delays). It should be noted that a peering relationship between two SIP User Agents (i.e., CMSs and/or EBPs) often results in two TCP connections, one for SIP transactions initiated in each direction. This is due to the fact most TCP connections are initiated using
+
+ephemeral source ports, and SIP transactions are initiated by sending SIP requests to a User Agent's well-known SIP port. As for securing each TCP connection with TLS, TLS clients typically cache TLS sessions based on specific remote IP address and port pairs; therefore, it is unlikely that TLS session caching using a common TLS master key can be used for both of the TLS sessions.
+
+The inter-domain signalling flow begins with CMS "A" sending an INVITE to EBP "A" (CMS "A" is initiating a SIP INVITE transaction and will signal the well-known SIP port on EBP "A"). A TLS session is required and may need to be established for the TCP connection if one does not already exist (which can be re-used) for this new transaction. Similarly, a TLS session is required for each hop in this INVITE transaction, and may require a TLS session to be established between EBP "A" and EBP "B", and also between EBP "B" and CMS "B".
+
+The 183 (Session Progress) response from CMS "B" is routed back through the EBPs to CMS "A" using the previously established TLS sessions. Once CMS "A" receives this 183 response, it sends a PRACK (Provisional ACK) directly to CMS "B". This PRACK is a SIP request which initiates a new transaction, and requires that a TLS session be established with CMS "B"'s well-known SIP port. CMS "B" sends a 200 OK response back to CMS "A" (using the same TLS session and TCP connection) as the final response to this PRACK transaction. Upon receiving a response to its initial INVITE, CMS "A" will also send an UPDATE request to CMS "B" over the previously established TLS session, to indicate that resource reservation has been completed. CMS "B" will respond with a 200 OK, completing this UPDATE transaction.
+
+Upon receiving the UPDATE, CMS "B" reserves any necessary resource and sends back a 180 (Ringing) provisional response to CMS "A" over the previously established TLS session. This provisional response will also initiate PRACK/200 OK transaction between the two CMSs, over the same TLS session.
+
+Once the terminating end answers the call, CMS "B" sends the 200 OK final response to the INVITE. However, this response is sent back via the EBPs using the same TLS sessions used for the INVITE. CMS "A" will acknowledge receipt of this 200 OK response by sending an ACK (a SIP request) directly to CMS "B". This ACK is sent using the previously established TLS session used for the first PRACK.
+
+Once the call is established, the example illustrates the case where the terminating end goes on hook. CMS "B" initiates a BYE/200 OK transaction by sending a BYE (SIP request) to CMS "A". As this BYE request is sent to the well-known SIP signalling port of CMS "A", it is very likely that CMS "B" will need to use a different TCP connection and TLS session than the ones used for sending SIP requests from CMS "A" to CMS "B" (assuming CMS "A" is using an ephemeral port for its TCP connection to CMS "B").
+
+As can be seen from this example, two TCP connections with two distinct TLS sessions may be required between two CMSs. It is important to support persistent and re-usable connections and TLS session caching in order to minimize impacts on CMS performance and call latency.
+
+![Sequence diagram titled 'Figure 14 – CMS – CMS Signalling Flow with Security'. It shows the interaction between two domains, A and B, for call setup. Domain A includes MTA A, CMTS A, CMS A, EBP A, KDC A, and DNS Server. Domain B includes KDC B, EBP B, CMS B, CMTS B, and MTA B. The sequence starts with 'Offhook and dial' at MTA A, followed by NTIFY, 200+CRX, and 200+SDP messages. CMS A sends an INVITE to EBP A, which is forwarded to EBP B and then to CMS B. CMS B sends a GateSet message to CMTS B and a TGS-Req to KDC B. KDC B performs a series of DNS lookups (CMS A FODN, CMS A Realm, KDC A FODN, KDC A IP Address) and a PKCROSS exchange with KDC A. KDC B returns a TGS-Rep to CMS B. CMS B then sends an AP Req to KDC B, which returns an AP Rep. CMS B sends a 183 SDP to EBP B, which is forwarded to EBP A and then to CMS A. CMS A sends a GateSet message to CMTS A and a PRACK to CMS B. CMS B returns a 200 OK to CMS A. Finally, CMS A sends an MDCX+SDP to MTA A, which returns a 100 response. CMS B sends an MDCX(reserve) to MTA B, which returns a 100 response. The diagram is labeled J.170_F14 at the bottom right.](c93c4b33a2b42c8dd6d82a354f2f89f1_img.jpg)
+
+Sequence diagram titled 'Figure 14 – CMS – CMS Signalling Flow with Security'. It shows the interaction between two domains, A and B, for call setup. Domain A includes MTA A, CMTS A, CMS A, EBP A, KDC A, and DNS Server. Domain B includes KDC B, EBP B, CMS B, CMTS B, and MTA B. The sequence starts with 'Offhook and dial' at MTA A, followed by NTIFY, 200+CRX, and 200+SDP messages. CMS A sends an INVITE to EBP A, which is forwarded to EBP B and then to CMS B. CMS B sends a GateSet message to CMTS B and a TGS-Req to KDC B. KDC B performs a series of DNS lookups (CMS A FODN, CMS A Realm, KDC A FODN, KDC A IP Address) and a PKCROSS exchange with KDC A. KDC B returns a TGS-Rep to CMS B. CMS B then sends an AP Req to KDC B, which returns an AP Rep. CMS B sends a 183 SDP to EBP B, which is forwarded to EBP A and then to CMS A. CMS A sends a GateSet message to CMTS A and a PRACK to CMS B. CMS B returns a 200 OK to CMS A. Finally, CMS A sends an MDCX+SDP to MTA A, which returns a 100 response. CMS B sends an MDCX(reserve) to MTA B, which returns a 100 response. The diagram is labeled J.170\_F14 at the bottom right.
+
+**Figure 14 – CMS – CMS Signalling Flow with Security**
+
+Figure 14 illustrates the beginning of an inter-domain call set-up. In this example, the signalling between the two CMSs is routed through two EBPs (Exterior Border Proxies). After one round-trip between the CMSs (after the 183 SDP message is received by CMS "A"), the rest of the CMS-CMS signalling is done directly, without the involvement of the intermediate EBPs.
+
+Figure 14 assumes that there are no prior SAs between the two CMSs and that CMS "B" does not possess a service ticket for CMS "A". It shows the key management flows necessary to establish the necessary SAs for this call.
+
+CMS "B" sends a TGS Request to its local KDC (KDC "B") to get a ticket for CMS "A". This TGS Request is sent at the same time as the Gate-Set message to the local CMTS. The key management flows continue in parallel with the subsequent DQoS flows (Gate-Set ACK) and also in parallel with some NCS signalling flows (CRCX from CMS "B" to MTA "B" and the 200+SDP response from MTA "B"). After the 200+SDP response, no more parallelism is possible.
+
+The next signalling message that CMS "B" sends out is the 183 SDP to EBP "B" that has to wait until CMS "B" obtains a ticket for CMS "A", in order to encrypt the media stream keying material inside SDP. To ensure synchronization, CMS "B" also waits until it establishes IPSec SAs with CMS "B", before sending the 183 SDP. This guarantees that when CMS "A" later sends a signalling message (PRACK) directly to CMS "B", IPSec SAs will already be established.
+
+Since CMS "A" is in a different realm (and not in KDC "B's" database), the TGS Request from CMS "B" causes KDC "B" to perform a DNS lookup to retrieve CMS "A's" realm name. After the DNS lookup is complete, KDC "B" will attempt to locate a ticket for KDC "A" in its local ticket cache. If it finds that ticket, it will immediately return to CMS "B" the cross-realm TGT needed to authenticate to KDC "A". If (in a rare circumstance) KDC "B" does not currently have a ticket for KDC "A", it will first have to perform DNS lookups to locate it and then perform a PKCROSS exchange with KDC "A" to obtain the KDC ticket.
+
+Once CMS "B" finally receives a cross-realm TGT for KDC "A", it has to send another TGS Request for KDC "A" and then finally obtain the service ticket for CMS "A". In order for CMS "B" to contact KDC "A", it will first have to perform two more DNS queries (one to get the KDC "A's" FQDN and another to get its IP address).
+
+After CMS "B" had obtained a ticket for CMS "A", it will initiate Kerberized IPsec key management with CMS "A" in order to set up SAs. After IPsec SAs are established, CMS "B" continues with signalling by sending 183 SDP SIP message to CMS "A", via the external border proxy EBP "B". The keying material inside 183 SDP is encrypted as specified in 7.4.1.4.2.1. Further SIP signalling between the two CMSes is sent directly, without the participation of the border proxies and using the just established IPsec SAs.
+
+### 7.4.2 Call Signalling Security Profile Matrix
+
+**Table 25 – Security profile matrix – Network call signalling**
+
+|                     | MTA-CMS                                                                                                                                                                                                             | CMS-CMS                                                                                                                                 | CMS-SIP Proxy/<br>SIP Proxy-SIP Proxy                                                                                                   |
+|---------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------|
+| Authentication      | Optional                                                                                                                                                                                                            | Yes                                                                                                                                     | Yes                                                                                                                                     |
+| Access control      | Optional                                                                                                                                                                                                            | Yes                                                                                                                                     | Yes                                                                                                                                     |
+| Integrity           | Optional                                                                                                                                                                                                            | Yes                                                                                                                                     | Yes                                                                                                                                     |
+| Confidentiality     | Optional                                                                                                                                                                                                            | Yes                                                                                                                                     | Yes                                                                                                                                     |
+| Non-repudiation     | No                                                                                                                                                                                                                  | No                                                                                                                                      | No                                                                                                                                      |
+| Security mechanisms | IPsec ESP with encryption and message integrity enabled<br>Authentication via Kerberos with PKINIT<br>Kerberized key management defined by IPCablecom<br>Security may be disabled through the provisioning process. | TLS with encryption and message integrity<br>Authentication via X.509 certificates (or symmetric keys when TLS session caching is used) | TLS with encryption and message integrity<br>Authentication via X.509 certificates (or symmetric keys when TLS session caching is used) |
+
+## 7.5 PSTN Gateway interface
+
+### 7.5.1 Reference architecture
+
+An IPCablecom PSTN Gateway consists of three functional components:
+
+- a Media Gateway Controller (MGC) which may or may not be part of the CMS;
+- a Media Gateway (MG); and
+- a Signalling Gateway (SG).
+
+These components are described in detail in ITU-T Rec. J.171.x.
+
+#### 7.5.1.1 Media Gateway Controller
+
+The Media Gateway Controller (MGC) is the PSTN gateway's overall controller. The MGC receives and mediates call-signalling information between the IPCablecom and the PSTN domains (from the SG), and it maintains and controls the overall state for all communications.
+
+#### 7.5.1.2 Media Gateway
+
+Media Gateways (MG) provide the bearer connectivity between the PSTN and the IPCablecom network.
+
+#### 7.5.1.3 Signalling Gateway
+
+IPCablecom provides support for SS7 signalling gateways. The SG contains the SG to MGC interface. Refer to ITU-T Rec. J.171.x for more detail on signalling gateways.
+
+The SS7 Signalling Gateway performs the following security-related functions:
+
+- Isolates the SS7 network from the IP network. Guards the SS7 network from threats such as information leakage, integrity violation, denial-of-service, and illegitimate use.
+- Provides mechanisms for certain trusted entities ("TCAP Users") within the IPCablecom network, such as Call Agents, to query external PSTN databases via TCAP messages sent over the SS7 network.
+
+### 7.5.2 Security services
+
+#### 7.5.2.1 MGC-MG interface
+
+*Authentication:* Both the MG and the MGC must be authenticated, in order to prevent a third party masquerading as either an authorized MGC or MG.
+
+*Access control:* MG resources should be made available only to authorized users – thus, access control is required at the MG.
+
+*Integrity:* must be assured in order to prevent tampering with the TGCP signalling messages – e.g., changing the dialled numbers.
+
+*Confidentiality:* TGCP signalling messages carry dialled numbers and other customer information, which must not be disclosed to a third party. Thus, confidentiality of the TGCP signalling messages is required.
+
+### 7.5.3 Cryptographic mechanisms
+
+#### 7.5.3.1 MGC-MG interface
+
+IPsec ESP MUST be used to both authenticate and encrypt the messages from MGC to MG and vice versa. Refer to 6.1 for details of how IPsec ESP is used within IPCablecom and for the list of available ciphersuites.
+
+### 7.5.4 Key management
+
+#### 7.5.4.1 MGC-MG interface
+
+Key management for MGC-MG interface is either IKE or Kerberos. Implementations MUST support IKE with pre-shared keys. Implementations MAY support IKE with X.509 certificates and they MAY support Kerberos using symmetric keys. For more information on the IPCablecom use of IKE, refer to 6.2.2. For more information on the IPCablecom use of Kerberos with symmetric keys, refer to 6.4.3 and 6.5.
+
+The key management protocol ensures that there is always a valid, non-expired MGC-MG Secret.
+
+### 7.5.5 MGC-MG summary security profile matrix
+
+**Table 26 – Security profile matrix – TCAP/IP and TGCP**
+
+|                     | <b>TGCP<br/>(MG-MGC)</b> |
+|---------------------|--------------------------|
+| Authentication      | Yes                      |
+| Access control      | Yes                      |
+| Integrity           | Yes                      |
+| Confidentiality     | Yes                      |
+| Non-repudiation     | No                       |
+| Security mechanisms | IPsec, IKE or Kerberos   |
+
+## 7.6 Media stream
+
+This security Recommendation allows for end-to-end ciphersuite negotiation so that the communicating parties can choose their preferred encryption and authentication algorithms for the particular communication.
+
+### 7.6.1 Security services
+
+#### 7.6.1.1 RTP
+
+*Authentication:* End-to-end authentication cannot be required, because the initiating party may want to keep their identity private. Optional end-to-end exchanges for both authentication and additional key negotiation are possible but are outside of the scope for IPCablecom.
+
+*Encryption:* The media stream between MTAs and/or MGs should be encrypted for privacy. Without encryption, the stream is vulnerable to eavesdropping at any point in the network.
+
+Key Distribution via the CMS, a trusted third party, assures the MTA (or MG) that the communication was established through valid signalling procedures, and with a valid subscriber. All this guarantees confidentiality (but not authentication).
+
+*Message integrity:* It is desirable to provide each packet of the media stream with a message authentication code (MAC). A MAC ensures the receiver that the packet came from the legitimate sender and that it has not been tampered with en route. A MAC defends against a variety of potential known attacks, such as replay, clogging, etc. It also may defend against as-yet-undiscovered attacks. Typically, a MAC consists of 8 or more octets appended to the message being protected. In some situations, where data bandwidth is limited, a MAC of this size is inappropriate. As a tradeoff between security and bandwidth utilization, a short MAC consisting of 2 or 4 octets is specified and selectable as an option to protect media stream packets. Use of the MAC during an end-to-end connection is optional; whether it is used or not is decided during the end-to-end ciphersuite negotiation (see 7.6.2.3.1).
+
+*Low complexity:* Media stream security must be easy to implement. Of particular concern is a PSTN gateway, which may have to apply security to thousands of media streams simultaneously. The encryption and MAC algorithms used with the PSTN gateway must be of low complexity so that it is practical to implement them on such a scale.
+
+#### 7.6.1.2 RTCP
+
+*Authentication:* See the above clause.
+
+*Encryption:* Within IPCablecom, RTCP messages are not permitted to contain the identity of the RTCP termination endpoint. Snooping on RTCP messages, therefore, does not reveal any subscriber-specific information but may reveal network usage and reliability statistics. RTCP encryption is optional.
+
+*Message integrity:* RTCP signalling messages (e.g., BYE) can be manipulated to cause denial-of-service attacks and alteration of reception statistics. To prevent these attacks, message integrity should be used for RTCP.
+
+### 7.6.2 Cryptographic mechanisms
+
+MTAs and MGs MUST have an ability to negotiate a particular encryption and authentication algorithm. If media security parameters are negotiated and RTP encryption is on (Transform ID is not RTP\_ENCR\_NULL), each media RTP packet MUST be encrypted for privacy. If RTP encryption is on, encryption MUST be applied to the RTP payload and MUST NOT be applied to the RTP header. Security MUST NOT be applied to RTP packets if the negotiated RTP ciphersuite is AUTH\_NULL and RTP\_ENCR\_NULL.
+
+Each RTP packet MAY include an optional message authentication code (MAC). The MAC algorithm can also be negotiated. The MAC computation MUST span the packet's unencrypted header and encrypted payload. The receiver MUST perform the same computation as the sender and it MUST discard the received packet if the value in the MAC field does not match the computed value.
+
+Keys for the encryption and MAC calculation MUST be derived from the End-End secret, which is exchanged between sending and receiving MTAs as described in 7.6.2.3.1.
+
+#### 7.6.2.1 RTP messages
+
+Figure 15 shows the format of an encoded RTP packet. IPCablecom MUST adhere to the RTP packet format as defined by RFC 1889 and RFC 1890 after being authenticated and decrypted (where the MAC bytes, if included, are stripped off as part of the authentication).
+
+The packet's header consists of 12 or more octets, as described in RFC 1889. The only field of the header that is relevant to the encoding process is the timestamp field.
+
+The RTP header has the format (RFC 1889) as shown in Figure 15.
+
+| 0                                        |   |   |   |    |   |   |   | 1 |    |   |   |   |   |   |   |   | 2               |   |   |   |   |   |   |   | 3 |   |   |   |   |   |   |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
+|------------------------------------------|---|---|---|----|---|---|---|---|----|---|---|---|---|---|---|---|-----------------|---|---|---|---|---|---|---|---|---|---|---|---|---|---|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--|
+| 0                                        | 1 | 2 | 3 | 4  | 5 | 6 | 7 | 8 | 9  | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7               | 8 | 9 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 0 | 1 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
+| V=2                                      |   | P | X | CC |   |   |   | M | PT |   |   |   |   |   |   |   | Sequence Number |   |   |   |   |   |   |   |   |   |   |   |   |   |   |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
+| Timestamp                                |   |   |   |    |   |   |   |   |    |   |   |   |   |   |   |   |                 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
+| Synchronization Source (SSRC) Identifier |   |   |   |    |   |   |   |   |    |   |   |   |   |   |   |   |                 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
+| Contributing Source (CSRC) Identifier    |   |   |   |    |   |   |   |   |    |   |   |   |   |   |   |   |                 |   |   |   |   |   |   |   |   |   |   |   |   |   |   |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
+
+**Figure 15 – RTP packet header format**
+
+The first twelve octets are present in every RTP packet, while the list of CSRC identifiers is present only when inserted by a mixer. See Figure 16.
+
+![Diagram of an encoded RTP packet structure. The packet is shown as a vertical stack of fields. From top to bottom: a variable-length CSRC identifier list (labeled '...', '(4 octets)'), a 'Timestamp' field (4 octets), another variable-length CSRC identifier list (labeled '...', '(4 or more octets)'), a 'Payload' field (0 or more octets), and an 'Optional MAC' field (4 octets). A vertical double-headed arrow on the left labeled 'Header' spans the first three fields. A vertical double-headed arrow in the middle labeled 'Encrypted' spans the 'Payload' field. A vertical double-headed arrow on the right labeled 'Authenticated' spans the 'Timestamp', the second CSRC list, the 'Payload', and the 'Optional MAC' field. The label 'J.170_F16' is at the bottom right.](633fb609c4b7e841224c558b9db215bf_img.jpg)
+
+Diagram of an encoded RTP packet structure. The packet is shown as a vertical stack of fields. From top to bottom: a variable-length CSRC identifier list (labeled '...', '(4 octets)'), a 'Timestamp' field (4 octets), another variable-length CSRC identifier list (labeled '...', '(4 or more octets)'), a 'Payload' field (0 or more octets), and an 'Optional MAC' field (4 octets). A vertical double-headed arrow on the left labeled 'Header' spans the first three fields. A vertical double-headed arrow in the middle labeled 'Encrypted' spans the 'Payload' field. A vertical double-headed arrow on the right labeled 'Authenticated' spans the 'Timestamp', the second CSRC list, the 'Payload', and the 'Optional MAC' field. The label 'J.170\_F16' is at the bottom right.
+
+**Figure 16 – Format of encoded RTP packet**
+
+In IPCablecom, an RTP packet will carry compressed audio from the sender's voice codec, or it will carry a message describing one or more events such as a DTMF tone, trunk or line signalling, etc. For simplicity, the former is referred to as a "voice packet" and the latter as an "event packet".
+
+A voice packet's payload consists of compressed audio from the sender's voice codec. The length of the payload is variable and depends on the voice codec as well as the number of codec frames carried by the packet.
+
+An event packet's payload consists of a message describing the relevant event or events. The format of the message is outside the scope of this Recommendation. The length of the payload is variable, but it will not exceed a known maximum value.
+
+For either type of packet, the payload **MUST** be encrypted. If the optional MAC is selected, the MAC field is appended to the end of the packet after the payload.
+
+Parameters representing RTP packet characteristics are defined as follows:
+
+- $N_c$ : the number of octets in one frame of compressed audio. Each codec has a well-defined value of  $N_c$ . In the case of a codec that encodes silence using short frames,  $N_c$  refers to the number of octets in a non silent frame.
+- $N_u$ : the number of speech samples in one frame of uncompressed audio. The number of speech samples represented by a voice packet is an integral multiple of  $N_u$ .
+- $N_f$ : the frame number. The first frame of the sender's codec has a value of zero for  $N_f$ . Subsequent frames increment  $N_f$  by one.  $N_f$  increments regardless of whether a frame is actually transmitted or discarded as silent.
+
+- $M_f$ : the maximum number of frames per packet.  $M_f$  is determined by the codec's frame rate and by the sender's packetization rate. The packetization rate is specified during communications set-up. For NCS signalling, it is a parameter in the LocalConnectionOptions – see ITU-T Rec. J.162.
+
+For example, suppose the speech sample rate is 8000 samples/s, the frame rate is 10 ms, the packetization rate is 30 ms, and the compressed audio rate is 16 000 bits/s. Then  $N_c = 20$ ,  $N_u = 80$ ,  $M_f = 3$ , and  $N_f$  counts the sequence 0, 1, 2.
+
+- $N_e$ : the maximum number of bytes that might be sent within the duration of one codec frame. It is assumed that an event packet can have a payload as large as that of a voice packet, but no longer. In the case of a block cipher, the cryptographic keys do not change after midstream codec changes. When a codec change does not require a corresponding key change, the value of  $N_e$  MUST be calculated as follows:
+
+$$N_e = \text{MAX} \{ N_{eK} \} \text{ for } K = 1, \dots, N$$
+
+where  $N_1, N_2, \dots, N_K$  are the different frame sizes for codecs that are supported by a particular endpoint.
+
+Otherwise,  $N_e = N_c$ , where  $N_c$  is the frame size for the current codec.
+
+- $N_m$ : the number of MAC octets. This value is 0, if the optional MAC is not selected; or 2 or 4, representing the MAC size if the optional MAC is selected.
+
+![Diagram illustrating RTP packet profile characteristics. It shows the hierarchy from an RTP packet down to an uncompressed frame. The RTP packet contains Header, Timestamp, CSCI, Payload, and MMH MAC (Nm bytes). The Payload contains multiple frames (Mf frames/packet), labeled Frame N (N-1), Frame N (1), and Frame N (N+1). Each frame is a Compressed frame consisting of octets (Ne octets/frame). The Compressed frame is mapped to an Uncompressed frame consisting of samples (Nu samples).](912a57b374babddd0201eecb2e9e1e4b_img.jpg)
+
+The diagram illustrates the structure of an RTP packet and its relationship to compressed and uncompressed frames. At the top, an RTP packet is shown with fields: Header, Timestamp, CSCI, Payload, and MMH MAC (Nm bytes). The Payload contains multiple frames, labeled as Mf (Frames/Packet). Below this, three frames are shown: Frame N (N-1), Frame N (1), and Frame N (N+1). Each frame is a Compressed frame consisting of octets, labeled as Ne (Octets/Frames). The Compressed frame is then shown as an Uncompressed frame consisting of samples, labeled as Nu (samples). The diagram uses lines and arrows to show the hierarchical relationship between these elements.
+
+Diagram illustrating RTP packet profile characteristics. It shows the hierarchy from an RTP packet down to an uncompressed frame. The RTP packet contains Header, Timestamp, CSCI, Payload, and MMH MAC (Nm bytes). The Payload contains multiple frames (Mf frames/packet), labeled Frame N (N-1), Frame N (1), and Frame N (N+1). Each frame is a Compressed frame consisting of octets (Ne octets/frame). The Compressed frame is mapped to an Uncompressed frame consisting of samples (Nu samples).
+
+**Figure 17 – RTP packet profile characteristics**
+
+##### 7.6.2.1.1 RTP timestamp
+
+According to RFC 1889, the timestamp field is a 32-bit value initially chosen at random. To IPCablecom, the timestamp MUST increment according to the codec sampling frequency. The timestamp in the RTP header MUST reflect the sampling instant of the first octet in each RTP packet presented as offset from the initial random timestamp value. The timestamp field MAY be used by the receiver to synchronize its decryption process to the encryption process of the sender.
+
+Based on the definition of the timestamp and the packet parameters described in the previous clause, the timestamp MUST equate to the value:  $((N_f \times N_u) + (\text{RTP initial timestamp})) \bmod 2^{32}$ , where  $N_f$  is the frame number of the first frame included in the packet.
+
+##### 7.6.2.1.2 Packet encoding requirements
+
+Prior to encoding the packets of an RTP stream, the sending MTA MUST derive the keys and parameters from the End-End Secret it shares with the receiving MTA, as specified in 7.6.2.3.3.
+
+An MTA MUST derive two distinct sets of these quantities, one set for processing outgoing packets and another set for processing incoming packets.
+
+###### 7.6.2.1.2.1 Encryption and MMH MAC option
+
+###### 7.6.2.1.2.1.1 Deriving an MMH MAC Key
+
+The MMH MAC Key size MUST be determined before generating the MMH MAC Key. The following algorithm specifies how to derive the MMH MAC Key when being used with block ciphers:
+
+$$\text{MMH MAC key size} = (M_f \times N_e) + N_h + N_m - 2 + P$$
+
+where:
+
+$M_f$  is the maximum number of frames per packet
+
+$N_e$  is maximum number of octets in one frame of compressed audio
+
+$N_h$  is the maximum number of octets in the RTP header, as defined in 7.6.2.1
+
+$N_m$  is the number of octets in the MAC
+
+Therefore,  $(M_f \times N_e) + N_h$  represents the maximum size of an RTP packet, and  $N_m - 2$  represents the additional two octets that are added to the key size when a four-octet MMH MAC is used. (The key size is the same as the maximum RTP packet size when a two-octet MMH MAC is used.)  $P$  is 0 or 1, as needed to make the MMH MAC key size an even number so that it is a multiple of the word size (2 bytes) used in the MMH MAC algorithm.
+
+The number of octets in the RTP header ranges from 12 to 72, inclusive, depending on the number of CSRC identifiers that are included (see RFC 1889). An implementation MUST choose  $N_h$  at least as large as required to accommodate the maximum number of CSRC identifiers that may occur during a session. An implementation MUST set  $N_h$  to 72 if the maximum number of CSRC identifiers is otherwise unknown.
+
+Since the key derivation procedure generates the MMH MAC key last (see 7.6.2.3.3.1), it is not necessary to generate a complete MMH MAC key at the start of the RTP session. Implementations MAY generate less than the full MMH MAC key and generate the rest later, as needed. For example, instead of using a value of  $N_e$  that reflects all possible codecs supported by an endpoint, an implementation might initially derive an MMH key of size  $(M_f \times N_c) + N_h + N_m - 2 + P$ , where  $N_c$  is the frame size for the currently selected codec. Later, after a codec change that results in a larger value of  $N_c$ , additional bytes for the MMH key may be generated.
+
+###### 7.6.2.1.2.1.2 RTP timestamp wrap-around
+
+Let us say that the initial RTP timestamp value is  $T_0$ . A timestamp wrap-around occurs when:
+
+- an RTP packet with sequence number  $i$  has a timestamp value  $2^{32} - \xi_1$  for  $0 < \xi_1 \leq \Delta T_{\text{MAX}}$ , where  $\Delta T_{\text{MAX}}$  is the maximum difference between two consecutive RTP timestamps;
+- an RTP packet with a sequence number  $i+1$  has a timestamp value  $\xi_2$  for  $0 \leq \xi_2 < \Delta T_{\text{MAX}}$ .
+
+The wrap-around point is between the RTP packets  $i$  and  $i+1$ .
+
+Each endpoint MUST keep a count  $N_{\text{WRAP}}$  of RTP timestamp wrap-arounds, with a range from 0 to  $2^{16} - 1$  and initialized to zero at the start of the connection.  $N_{\text{WRAP}}$  MUST be incremented by the sender right after the wrap-around point.  $N_{\text{WRAP}}$  MUST also be incremented by the receiver before it decrypts any RTP packets after the wrap-around point.
+
+###### 7.6.2.1.2.2 Block cipher encryption of RTP packets
+
+The AES block cipher must be supported for encryption of RTP packets. The following subclauses specify how to support any block cipher, including AES.
+
+###### 7.6.2.1.2.2.1 Block termination
+
+If an implementation supports block ciphers, residual block termination (RBT) MUST be used to terminate streams that end with less than a full block of data to encrypt (see 9.3).
+
+###### 7.6.2.1.2.2.2 Initialization Vector
+
+An Initialization Vector (IV) is required when using a block cipher in CBC mode to encrypt RTP packet payloads. The size of an IV is the same as the block size for the particular block cipher. For example, the IV size for DESX and 3-DES is 64 bits, while for AES-CBC it is 128 bits. In order to calculate the IV, each endpoint MUST keep track of  $N_{\text{WRAP}}$  – the count of timestamp wrap-arounds during this RTP session; see 7.6.2.1.2.1.2. The IV MUST be calculated new for each RTP packet as specified below:
+
+- 1) Take the first N bits of the header, where  $N = \min(\text{cipher block size}, \text{RTP header size})$ .
+- 2) In the result of the previous step, replace the first 16 bits of the header with the 16-bit value of  $N_{\text{WRAP}}$ , MSB first.
+- 3) Pad the result of previous step with 0s on the right, so that the resulting bit string is equal in size to the cipher block size.
+- 4) XOR the result of the previous step with the RTP Initialization Key (defined in 7.6.2.3.3.1). The size of the RTP Initialization Key is the same as the cipher block size.
+- 5) Encrypt the result of the previous step using the same block cipher that is used to encrypt RTP packets, but in ECB mode. The result of this step is the Initialization Vector for this RTP packet.
+
+###### 7.6.2.1.2.2.3 MMH-MAC pad derivation when using a block cipher
+
+The MMH-MAC algorithm requires a one-time pad for each RTP packet. The MMH-MAC Pad MUST be derived by performing the MMH Function on the Block Cipher's IV. For a 2-byte MMH-MAC, use the MMH Function described in 9.7.1.1; for a 4-byte MMH-MAC, use the MMH Function described in 9.7.1.2.
+
+The IV value is calculated according to 7.6.2.1.2.2.2 for block ciphers that require an IV. Even if the block cipher does not require an IV, one MUST be derived according to 7.6.2.1.2.2.2 and used as the basis of the MMH-MAC pad derivation.
+
+A key is also required by the MMH digest function in order to calculate the pad. The MMH MAC key derived in 7.6.2.3.3.1 MUST be truncated according to 9.7.2.2 and MUST then be used as the key to the MMH digest. Accordingly, the MMH MAC key is truncated to:
+
+$$\langle \text{size of IV} \rangle + N_m - 2$$
+
+Where  $\langle \text{size of IV} \rangle$  is 16 bytes for AES,  $N_m$  is the size of the MMH MAC in bytes, as defined in 7.6.2.1, and  $N_m - 2$  represents the additional two octets that are added to the key size when a four-octet MMH MAC is used. (The truncated key size is the same as the IV size when a two-octet MMH MAC is used.)
+
+##### 7.6.2.1.3 Packet decoding requirements
+
+Prior to decoding the packets of an RTP stream, the receiving MTA MUST derive the keys and parameters from the End-End Secret it shares with the sending MTA, as specified in 7.6.2.3.3.
+
+The derived quantities MUST match the corresponding quantities at the sending MTA.
+
+###### 7.6.2.1.3.1 Timestamp tolerance check
+
+Before processing a received packet, the receiver SHOULD perform a sanity check on the timestamp value in the RTP header, consisting of the items 1 and 2 below:
+
+- 1) Beginning with the RTP timestamp in the first packet received from a sender, the receiver calculates an expected value for the timestamp of the sender's next RTP packet based on timestamps received in the sender's previous packets for the session.
+- 2) The next packet is rejected without being processed if its timestamp value is outside a reasonable tolerance of the expected value. (Timestamps from rejected packets are not to be used to predict future packets). The tolerance value is defined to be:
+  - a) sufficiently tight to ensure that an invalid timestamp value cannot derail the receiver's state so much that it cannot quickly recover to decrypting valid packets;
+  - b) able to account for known differences in the expected and received timestamp values, such as might occur at call startup, codec switch-over and due to sender/receiver clock drift.
+
+If the timestamp value in the RTP headers from a sender never comes back within the acceptable range, the receiver discontinues the session.
+
+At the receipt of each packet, the receiver adjusts its time relationship with the sender within the acceptable tolerance range of estimated values.
+
+###### 7.6.2.1.3.2 Packet authentication
+
+If authentication is used on an RTP packet stream, verification of the MAC MUST be the first step in the packet decoding process. When the timestamp tolerance check is performed, the MAC MAY be verified on packets with valid RTP timestamps immediately after the check is completed.
+
+If the MAC does not verify, the packet MUST be rejected.
+
+#### 7.6.2.2 RTCP messages
+
+##### 7.6.2.2.1 RTCP format
+
+RFC 1889 defines the packet format of RTCP messages as in Figure 18.
+
+| v=2  | p | count | pkt type | Length |
+|------|---|-------|----------|--------|
+| SSRC |   |       |          |        |
+|      |   |       |          |        |
+|      |   |       |          |        |
+
+Figure 18 – RTCP packet format
+
+The RTCP packet type could be SR (sender reports), RR (receiver reports), SDES (source description), BYE (leaving conference), and APP (application-specific function). The length varies depending on the message type, but generally around 40 bytes.
+
+##### 7.6.2.2.2 RTCP encryption
+
+The RTCP messages MUST always be encrypted in their entirety when the negotiated encryption algorithm is a block cipher in CBC mode. RTCP messages MUST NOT be encrypted when the negotiated encryption algorithm is RTCP\_ENCR\_NULL. However, the encoded RTCP messages MUST still be formatted according to 7.6.2.2.2 when RTCP\_ENCR\_NULL is selected in conjunction with a non-NULL authentication algorithm (e.g., HMAC-SHA1-96 or HMAC-MD5-96). Security MUST NOT be applied to RTCP packets if the negotiated RTCP ciphersuite is RTCP\_AUTH\_NULL and RTCP\_ENCR\_NULL. After the message is encrypted, an
+
+additional header and MAC (Message Authentication Code) are added. The result packet has the format in Figure 19.
+
+![](708e7ef81dbf726e558047afe57d6ff7_img.jpg)
+
+|                           |
+|---------------------------|
+| Sequence number (4 bytes) |
+| IV                        |
+| Encrypted RTCP message    |
+| MAC                       |
+
+**Figure 19 – RTCP encrypted packet format**
+
+The first 4 bytes MUST be the sequence number, MSB first. The initial sequence number for each direction of traffic MUST be 0. Afterwards, the sequence number for each direction MUST be incremented by 1. Generally, one RTCP message is sent every 5 seconds for each channel. Thus, 32 bits for the sequence number field would be big enough for any connections without wrapping around.
+
+The IV (Initialization Vector) MUST immediately follow the sequence number. The IV MUST be randomly generated by the sender for each RTCP message and the IV size MUST be the same as the block size for the selected block cipher. The Initialization Vector (IV) MUST NOT be included when RTCP\_ENCR\_NULL is used.
+
+The original cleartext RTCP message encrypted in its entirety MUST immediately follow the IV. The MAC (Message Authentication Code) computed over the concatenation of the sequence number, the IV, and the encrypted message MUST follow the encrypted RTCP message. The size of the MAC is algorithm-dependent.
+
+##### 7.6.2.2.3 Sequence numbers
+
+The receiver of RTCP messages SHOULD keep a sliding window of the RTCP sequence numbers. The size of the sliding window  $W_{\text{RTCP}}$  depends on the reliability of the UDP transport and is locally configured at each endpoint.  $W_{\text{RTCP}}$  SHOULD be 32 or 64. The sliding window is most efficiently implemented with a bit mask and bit shift operations.
+
+When the receiver is first ready to receive RTCP packets, the first sequence number in this window MUST be 0 and the last MUST be  $W_{\text{RTCP}} - 1$ . All sequence numbers within this window MUST be accepted the first time but MUST be rejected when they are repeated. All sequence numbers that are smaller than the "left" edge of the window MUST be rejected.
+
+When an authenticated RTCP packet with a sequence number that is larger than the "right" edge of the window is received, that sequence number is accepted and the "right" edge of the window is replaced with this sequence number. The "left" edge of the window is updated in order to maintain the same window size.
+
+When for a window  $(S_{\text{right}} - W_{\text{RTCP}} + 1, S_{\text{right}})$ , sequence number  $S_{\text{new}}$  is received and  $S_{\text{new}} > S_{\text{right}}$ , then the new window becomes:
+
+$$(S_{\text{new}} - W_{\text{RTCP}} + 1, S_{\text{new}})$$
+
+##### 7.6.2.2.4 Block termination
+
+Residual block termination (RBT) MUST be used to terminate RTCP messages that end with less than a full block of data to encrypt (see 9.3).
+
+##### 7.6.2.2.5 RTCP message encoding
+
+Each RTCP message MUST be encoded using the following procedure:
+
+- 1) A random IV is generated.
+- 2) The entire RTCP message is encrypted with the selected block cipher and the just generated IV.
+- 3) The current sequence number, the IV, and the encrypted RTCP message are concatenated in that order.
+- 4) The MAC is computed (using the selected MAC algorithm) over the result in step 3) and appended to the message.
+
+##### 7.6.2.2.6 RTCP message decoding
+
+Each RTCP message MUST be decoded using the following procedure:
+
+- 1) Regenerate the MAC code and compare with the received value. If the two do not match, the message is dropped.
+- 2) The sequence number is verified based on the sliding window approach specified in 7.6.2.2.3. If the sequence number is rejected, the message is dropped. The sliding window is also updated as specified in 7.6.2.2.3.
+- 3) The RTCP message is decrypted with the shared encryption key and with the IV that is specified in the message header.
+
+#### 7.6.2.3 Key management
+
+The key management specified here for end-to-end communication is identical in the cases of the MTA-to-PSTN and MTA-to-MTA communications. In the case of the MTA-to-PSTN communications, one of the MTAs is replaced by a MG (Media Gateway).
+
+The descriptions below refer to MTA-to-MTA communications only for simplicity. In this context, an MTA actually means a communication endpoint, which can be an MTA or a MG. In the case that the endpoint is a MG, it is controlled by an MGC instead of a CMS.
+
+During call set-up  $MTA_0$  (the initiating MTA) and  $MTA_1$  (the terminating MTA) exchange randomly generated keying material, carried inside the call signalling messages. Call signalling messages are themselves protected by IPsec ESP or TLS at each hop. This keying material is then used to generate the AES-CBC keys used to protect both RTP and RTCP messages between the two MTAs.
+
+$MTA_0$  generates two randomly generated values: End-End  $Secret_0$  (46-bytes) and  $Pad_1$  (46-bytes).
+
+$MTA_1$  generates two randomly generated values: End-End  $Secret_1$  (46-bytes) and  $Pad_0$  (46-bytes).
+
+$MTA_0$  uses End-End  $Secret_1$  and  $Pad_1$  to derive encryption and authentication keys to be applied to its outbound traffic and used by  $MTA_1$  to decrypt and authenticate it.
+
+$MTA_1$  uses End-End  $Secret_0$  and  $Pad_0$  to derive encryption and authentication keys to be applied to its outbound traffic, and used by  $MTA_0$  to decrypt and authenticate it. As a result, both  $MTA_0$  and  $MTA_1$  contribute randomly generated bytes to all of the keying material for both RTP and RTCP traffic.
+
+The distribution of the end-to-end keying material is specific to the call signalling from ITU-T Rec. J.162 and is described in the following subclauses.
+
+##### 7.6.2.3.1 Key management over NCS
+
+Figure 20 shows the actual NCS messages that are used to carry out the distribution of end-to-end keys. Each NCS message that is involved in the end-to-end key management is labelled with a number of the corresponding key management interface.
+
+The name of each NCS message is in bold. Below the NCS message name is the information needed in the NCS message, in order to perform end-to-end key distribution. Messages between the CMSs are labelled as SIP+ messages.
+
+![Sequence diagram showing end-end secret distribution over NCS between Source MTA or MG (MTA0), Source CMS or MGC (CMS0), Dest CMS or MGC (CMS1), and Dest MTA or MG (MTA1).](da85343976fdbb19f866d9ddbdad0eae_img.jpg)
+
+The diagram illustrates the sequence of messages for end-end secret distribution over NCS. It involves four entities: Source MTA or MG ( $MTA_0$ ), Source CMS or MGC ( $CMS_0$ ), Dest CMS or MGC ( $CMS_1$ ), and Dest MTA or MG ( $MTA_1$ ).
+
+Key management interfaces are numbered 1) through 7):
+
+- 1) CRCX**: From  $CMS_0$  to  $MTA_0$ . Content: List of RTP ciphersuites, List of RTCP ciphersuites.
+- 2) ACK**: From  $MTA_0$  to  $CMS_0$ . Content: Endpoint Connection ID, End-End Secret<sub>0</sub>Pad<sub>1</sub>, List of RTP ciphersuites, List of RTCP ciphersuites.
+- 3) INVITE (no-ring)**: From  $CMS_0$  to  $CMS_1$ . Content: End-End Secret<sub>0</sub>Pad<sub>1</sub>, List of RTP ciphersuites, List of RTCP ciphersuites.
+- 4) CRCX**: From  $CMS_1$  to  $MTA_1$ . Content: End-End Secret<sub>0</sub>Pad<sub>1</sub>, List of RTP ciphersuites, List of RTCP ciphersuites.
+- 5) ACK**: From  $MTA_1$  to  $CMS_1$ . Content: End-End Secret<sub>1</sub>Pad<sub>0</sub>, List of RTP ciphersuites, List of RTCP ciphersuites.
+- 6) 2000 OK**: From  $CMS_1$  to  $CMS_0$ . Content: End-End Secret<sub>1</sub>Pad<sub>0</sub>, List of RTP ciphersuites, List of RTCP ciphersuites.
+- 7) MDCX**: From  $CMS_0$  to  $MTA_0$ . Content: Endpoint Connection ID, End-End Secret<sub>1</sub>Pad<sub>0</sub>, List of RTP ciphersuites, List of RTCP ciphersuites.
+
+Other messages shown in the sequence include:
+
+- NTFY (digits)**: From  $MTA_0$  to  $CMS_0$ .
+- ACK**: From  $MTA_0$  to  $CMS_0$ .
+- MDCX**: From  $MTA_0$  to  $CMS_0$ .
+- ACK**: From  $MTA_0$  to  $CMS_0$ .
+- RQNT (ring)**: From  $CMS_1$  to  $MTA_1$ .
+- NTFY**: From  $MTA_1$  to  $CMS_1$ .
+- MDCX**: From  $MTA_1$  to  $CMS_1$ .
+- ACK**: From  $MTA_1$  to  $CMS_1$ .
+
+IPsec ESP messages are indicated by dashed arrows between  $MTA_0$  and  $CMS_0$ ,  $CMS_0$  and  $CMS_1$ , and  $CMS_1$  and  $MTA_1$ .
+
+Legend:
+
+- AKS: Acknowledge
+- CRCX: Create Connection
+- MDCX: Modify Connection
+- NTFY: Notify
+- RQNT: Request for Notification
+
+J.170\_F20
+
+Sequence diagram showing end-end secret distribution over NCS between Source MTA or MG (MTA0), Source CMS or MGC (CMS0), Dest CMS or MGC (CMS1), and Dest MTA or MG (MTA1).
+
+Figure 20 – End-End secret distribution over NCS
+
+Figure 20 shows that before the start of this scenario, both the source and destination MTAs had already established an IPsec ESP session with their local CMS. It is also assumed that CMS-CMS signalling is secure.
+
+This allows the End-End Secrets to be distributed securely, with privacy, integrity and anti-replay mechanisms already in place. The CMSs have access to this keying material but are trusted by the MTAs.
+
+###### **7.6.2.3.1.1 NULL ciphersuite combinations and ordering**
+
+RTP\_ENCR\_NULL MUST only be used in conjunction with AUTH\_NULL. RTP packets, with authentication but no encryption, are not allowed.
+
+RTCP\_AUTH\_NULL MUST only be used in conjunction with RTCP\_ENCR\_NULL. RTCP messages with encryption and without authentication are not allowed.
+
+Both RTP and RTCP security must be enabled or disabled together. The following five combinations MUST NOT be generated.
+
+- RTP NULL encryption and RTP non-NULL authentication;
+- RTCP non-NULL encryption & RTCP NULL authentication;
+- RTP non-NULL encryption and RTCP NULL authentication;
+- RTP NULL encryption and RTCP non-NULL authentication;
+- RTP NULL encryption and RTCP non-NULL encryption.
+
+If the MTA receives LocalConnectionOptions parameter that meet the above combinations, the MTA MUST return the error code 524 (Internal inconsistency in LocalConnectionOptions). Otherwise, if the MTA receives RemoteConnectionDescriptor parameter that meet the above combinations, then the MTA MUST return the error code 505 (Unsupported RemoteConnectionDescriptor).
+
+For both RTP and RTCP ciphersuite lists exchanged during ciphersuite negotiation, the combination of NULL encryption and NULL authentication algorithms MUST always be included last. For example, the list of RTP ciphersuites "60/50;62/51;64/51" is not allowed, while the list of RTP ciphersuites "62/51;64/51;60/50", or "60/50" is allowed. If the list of ciphersuites in LocalConnectionOptions includes the NULL authentication and NULL encryption combination (60/50 for RTP, and 80/70 for RTCP), but this combination is not the last in the list, the MTA MUST return error code 524 (Internal inconsistency in LocalConnectionOptions). Otherwise, if this combination is not last in a RemoteConnectionDescriptor, error code 505 (Unsupported RemoteConnectionDescriptor) MUST be returned.
+
+###### **7.6.2.3.1.2 Ciphersuite negotiation for MTAs**
+
+This Recommendation only defines security for RTP/RTCP media streams; therefore, ciphersuite negotiation applies only to RTP/RTCP media streams. Use of security for any other type of media streams is not specified.
+
+An MTA MUST perform RTP and RTCP ciphersuite negotiation when processing any of the following:
+
+- a CreateConnection command;
+- a ModifyConnection command with a RemoteConnectionDescriptor parameter;
+- a ModifyConnection command where the LocalConnectionOptions parameter includes ciphersuite fields.
+
+An MTA MUST NOT perform ciphersuite negotiation in any other case. The steps involved in ciphersuite negotiation are the following:
+
+- 1) An approved list of ciphersuites is formed by taking the intersection of the internal list of ciphersuites and ciphersuites allowed by the LocalConnectionOptions parameter, subject to the constraints specified in 7.6.2.3.1.1. The internal list of ciphersuites contains the ciphersuites that the MTA supports and which this Recommendation requires. If the LocalConnectionOptions parameter was not included, or if the ciphersuite fields were not provided in the LocalConnectionOptions parameter, the approved list of ciphersuites contains the previously agreed upon approved list, or if no such list exists, the internal list of ciphersuites.
+- 2) If the approved list of ciphersuites is empty, an error response MUST be generated, error code 532 (Unsupported value(s) in LocalConnectionOptions).
+- 3) Otherwise, a negotiated list of ciphersuites is formed by taking the intersection of the approved list of ciphersuites and ciphersuites allowed by the RemoteConnectionDescriptor parameter (if present), subject to the constraints specified in 7.6.2.3.1.1. If a RemoteConnectionDescriptor was not provided, the negotiated list of ciphersuites thus contains the approved list of ciphersuites. If a RemoteConnectionDescriptor parameter is provided without fields containing the RTP and RTCP ciphersuite lists, then the RTP AUTH\_NULL/RTP\_ENCR\_NULL and RTCP\_AUTH\_NULL/RTCP\_ENCR\_NULL ciphersuites are assumed for the remote endpoints, and the regular ciphersuite negotiation process continues (i.e., the negotiated list of ciphersuites is formed by taking the intersection of the approved list of ciphersuites and the RTP AUTH\_NULL/RTP\_ENCR\_NULL and RTCP\_AUTH\_NULL/RTCP\_ENCR\_NULL ciphersuites).
+- 4) If the negotiated list of ciphersuites is empty, a ciphersuite negotiation failure has occurred and an error response MUST be generated. If a RemoteConnectionDescriptor parameter was provided, two different error codes can be returned:
+  - a) If the endpoint does not support any of the ciphersuites allowed by the RemoteConnectionDescriptor, error code 505 (Unsupported RemoteConnectionDescriptor) MUST be used.
+  - b) If the endpoint does support at least one of the ciphersuites, but the negotiated list of ciphersuites ended up being empty, error code 506 (Unable to satisfy both LocalConnectionOptions and RemoteConnectionDescriptor) MUST be used.
+- 5) Otherwise, ciphersuite negotiation has succeeded, and the negotiated list of ciphersuites is returned in the LocalConnectionDescriptor parameter. Note that both LocalConnectionOptions and the RemoteConnectionDescriptor parameters can contain a list of ciphersuites that MUST be ordered by preference provided by the CMS in the RemoteConnectionDescriptor parameter. When both are supplied, the MTA SHOULD adhere to the preferences provided by the CMS in the RemoteConnectionDescriptor parameter, and otherwise, the MTA SHOULD adhere to the preferences provided in the LocalConnectionOptions parameter. If the MTA receives a RemoteConnectionDescriptor parameter with AUTH\_NULL/RTP\_ENCR\_NULL for RTP or RTCP\_AUTH\_NULL/RTCP\_ENCR\_NULL for RTCP that is not last in the list, it MUST return the error code 505 (Unsupported RemoteConnectionDescriptor).
+
+The following requirements apply during ciphersuite negotiation:
+
+- A CMS MUST be capable of sending the allowable lists of ciphersuites for RTP and/or RTCP in the LocalConnectionOptions parameter of a CreateConnection command (CRCX) or a ModifyConnection command (MDCX) in the order of preference specified by the operator subject to the constraints specified in 7.6.2.3.1.1.
+
+- Whenever possible, a MTA SHOULD select the first supported ciphersuite for RTP and the first supported ciphersuite for RTCP in the RemoteConnectionDescriptor parameter. This allows the MTA to immediately start sending RTP and RTCP packets to the other MTA. An MTA MAY instead select alternate ciphersuites specified by the other MTA.
+- When returning a LocalConnectionDescriptor and the negotiated list of RTP and RTCP ciphersuites is NULL, an MTA MUST NOT include an End-End Secret or Pad.
+- When returning a LocalConnectionDescriptor and the negotiated list of RTP and RTCP ciphersuites contains at least one non-NULL selection each, an MTA MUST include an End-End Secret (for incoming RTP and RTCP packets) and MAY include a Pad value (for outgoing RTP and RTCP packets). The following rules apply:
+  - 1) The MTA MUST generate a new End-End Secret when responding to a CreateConnection command.
+  - 2) The MTA MUST generate a new End-End Secret when responding to a ModifyConnection command if the remote connection address (e.g., IP Address) or the remote transport address (e.g., port) are not identical to what was previously assigned.
+  - 3) The MTA MUST use the existing End-End Secret when responding to a ModifyConnection command where there was no previous RemoteConnectionDescriptor provided.
+  - 4) The MTA MUST generate a new Pad when responding to a CreateConnection command without a RemoteConnectionDescriptor.
+  - 5) The MTA MUST generate a new Pad when generating a new End-End Secret in response to a ModifyConnection command without a RemoteConnectionDescriptor.
+  - 6) If not otherwise required, the MTA MAY generate a new Pad when generating a new End-End Secret.
+  - 7) The MTA MUST NOT generate a new Pad when not generating a new End-End Secret.
+- If, in response to a CreateConnection command, the list of ciphersuites selected for RTP contains at least one non-NULL encryption or authentication algorithm, before sending the response message, an MTA MUST:
+  - 1) Establish inbound RTP security based on the preferred (first) RTP ciphersuite, its End-End Secret (which it generated), and a Pad value (if included in the RemoteConnectionDescriptor), as described in 7.6.2.3.3.1.
+  - 2) If a RemoteConnectionDescriptor was included and it contains media security attributes, establish outbound RTP security based on the selected RTP ciphersuite, End-End Secret (generated by the other MTA), and a Pad value (which it may have generated) as described in 7.6.2.3.3.1.
+  - 3) If connection mode allows, be ready to receive RTP packets, which may arrive any time after the Response message is sent.
+- If, in response to a CreateConnection command, the list of ciphersuites for RTCP contains at least one non-NULL encryption algorithm, before sending the response message, an MTA MUST:
+  - 1) Establish inbound RTCP security based on the preferred (first) RTCP ciphersuite, its End-End Secret (which it generated), and a Pad value (if included in the RemoteConnectionDescriptor), as described in 7.6.2.3.3.1.
+  - 2) If a RemoteConnectionDescriptor was included and it contained media security attributes, establish outbound RTCP security based on the selected RTCP ciphersuite, End-End Secret (generated by the far-end MTA), and a Pad value (which it may have generated) as described in 7.6.2.3.3.1.
+
+3) Be ready to receive RTCP packets, which may arrive any time after the Response message is sent.
+
+- If, in response to a ModifyConnection command that includes a RemoteConnectionDescriptor, and negotiated lists of ciphersuites for RTP and RTCP contain at least one non-NULL encryption or authentication algorithm each, before sending the response message, an MTA MUST:
+
+- 1) If a Pad was included in the RemoteConnectionDescriptor and it is different from a Pad that may have previously been received, remove any existing inbound RTP keys and generate new ones, based on the keys that are generated from both the End-End Secret (generated locally) and the Pad (generated by the other MTA). The MTA MUST re-initialize the RTP timestamp if new keys are generated The ciphersuites used for these inbound keys are taken from the RemoteConnectionDescriptor parameter just received from the CMS.
+- 2) If a Pad was included in the RemoteConnectionDescriptor and it is different from a Pad that may have previously been received, remove any existing inbound RTCP keys and generate new ones, based on the keys that are generated from both the End-End Secret (generated locally) and the Pad (generated by the other MTA). The MTA MUST re-initialize RTCP sequence numbers if new keys are generated. The ciphersuites used for these inbound keys are taken from the RemoteConnectionDescriptor parameter just received from CMS.
+- 3) If the RemoteConnectionDescriptor parameter was received without a Pad, check if the first RTP ciphersuite field in the RemoteConnectionDescriptor parameter differs from the one that the MTA originally selected. Also, check to see if a Pad had been previously received. If the ciphersuites differ, or if a Pad had been previously received, perform the following steps:
+  - a) Remove any existing inbound RTP key.
+  - b) If the new RTP ciphersuite is non-NULL, generate new inbound RTP keys and RTP timestamp from the same End-End Secret (generated locally) as the last time, as specified in 7.6.2.3.3.1.
+- 4) If the RemoteConnectionDescriptor parameter was received without a Pad, check if the first RTCP ciphersuite field in the RemoteConnectionDescriptor parameter differs from the one that the MTA originally selected. Also, check to see if a Pad had been previously received. If the ciphersuites differ, or if a Pad had been previously received, perform the following steps:
+  - a) Remove any existing inbound RTCP key.
+  - b) If the new RTCP ciphersuite is non-NULL, generate new inbound RTCP keys from the same End-End Secret (generated locally) as the last time, as specified in 7.6.2.3.3.1, and reset the RTCP sequence number to 0.
+- 5) If the End-End Secret included in the RemoteConnectionDescriptor has changed or the negotiated RTP ciphersuite has changed, perform the following steps:
+  - a) Remove any existing outbound RTP keys.
+  - b) If the new list of RTP ciphersuites is non-NULL, generate new outbound RTP keys, based on the End-End Secret (generated by the other MTA) and the Pad (generated locally), and generate a new RTP timestamp.
+
+- 6) If the End-End Secret included in the RemoteConnectionDescriptor has changed or the negotiated RTCP ciphersuite has changed, perform the following steps:
+    - a) Remove any existing outbound RTCP keys
+    - b) If the new list of RTCP ciphersuites is non-NULL, generate new outbound RTCP keys, based on the End-End Secret (generated by the other MTA) and the Pad (generated locally), and reset the RTCP sequence number to 0.
+  - 7) Be ready to send RTCP messages to and receive RTCP messages from the remote MTA. If connection mode allows, be ready to send and receive RTP messages with the remote MTA. If the list of ciphersuites for RTP was sent within a ModifyConnection command, the CMS MAY send an inactive directive to the MTA in the same command. The MTA should be returned to active status only when the new ciphersuite negotiation is complete.
+- If, in response to a ModifyConnection command that does not include a RemoteConnectionDescriptor, and negotiated lists of ciphersuites for RTP and RTCP contain at least one non-NULL encryption or authentication algorithm each, before sending the response message, an MTA MUST:
+    - 1) If the first RTP ciphersuites field in the negotiated list differs from the one that the MTA previously selected, then perform the following steps:
+      - a) Remove any existing inbound RTP keys.
+      - b) Generate new inbound RTP keys from the previous End-End Secret (locally generated) and Pad (generated by the other MTA), and generate a new RTP timestamp.
+    - 2) If the first RTCP ciphersuites field in the negotiated list differs from the one that the MTA previously selected, then perform the following steps:
+      - a) Remove any existing inbound RTCP keys.
+      - b) Generate new inbound RTCP keys from the previous End-End Secret (locally generated) and Pad (generated by the other MTA), and reset the RTCP sequence number to 0.
+    - 3) Be ready to send RTCP messages to and receive RTCP messages from the remote MTA. If connection mode allows, be ready to send and receive RTP messages with the remote MTA. If the list of ciphersuites for RTP was sent within a ModifyConnection command, the CMS MAY send an inactive directive to the MTA in the same command. The MTA should be returned to active status only when the new ciphersuite negotiation is complete.
+  - If an MTA receives a ModifyConnection command, and the resulting intersection of ciphersuites results in NULL encryption and authentication algorithms for RTP and RTCP, then the MTA MUST remove any existing RTP and RTCP keys and do not perform security on the RTP and RTCP packets.
+  - If an MTA returns a LocalConnectionDescriptor parameter, it MUST return the latest negotiated list of ciphersuites.
+
+The following message flow is informative. Each of the numbered flows in Figure 20 is described below:
+
+- 1) CMS<sub>0</sub> → MTA<sub>0</sub>
+
+CMS<sub>0</sub> may send the allowable lists of ciphersuites for the new communication to MTA<sub>0</sub> in the CreateConnection (CRCX) command, inside the LocalConnectionOptions parameter, if the CMS has been configured to do so. The ciphersuites are provided in the order of preference specified by the operator subject to the constraints specified in 7.6.2.3.1.1. There
+
+can be two lists of ciphersuites, one list for RTP security and one for RTCP security. Each of these two lists may be included to specify the list of allowable ciphersuites, however ciphersuite negotiation will take place for both RTP and RTCP irrespective of whether the lists are included or not.
+
+If RTP and/or RTCP ciphersuites are included but do not adhere to the rules provided in 7.6.2.3.1.1, the MTA returns an error, e.g., 524 (Internal inconsistency in LocalConnectionOptions).
+
+###### 2) $MTA_0 \rightarrow CMS_0$
+
+$MTA_0$  performs ciphersuite negotiation according to the ciphersuite negotiation procedure described above, and returns a non-empty list of RTP ciphersuites in the response message. This list contains the list of  $MTA_0$ 's list of allowed ciphersuites in the order of preference specified by  $CMS_0$  if the LocalConnectionOptions ciphersuites parameter(s) is included in step 1, as specified above. If RTP or RTCP ciphersuite negotiation fails,  $MTA_0$  returns an error code as specified above.
+
+If the lists of negotiated ciphersuites for RTP and RTCP contain at least one non-NULL combination each,  $MTA_0$  generates the End-End  $Secret_0$  and  $Pad_1$  value and returns them along with the ciphersuites in the LocalConnectionDescriptor parameter. For further details on the NCS message syntax, refer to ITU-T Rec. J.162. Note that the NULL authentication and NULL encryption combinations will be at the end of each ciphersuite list.
+
+The response message also includes the ConnectionId and the EndpointId for  $MTA_0$  as described in ITU-T Rec. J.162. The pair (ConnectionId EndpointId) uniquely identifies this connection, where the EndpointId is an NCS identifier for  $MTA_0$ .
+
+If the list of ciphersuites for RTP contains at least one non-NULL encryption or authentication algorithm, before sending the response message,  $MTA_0$  must:
+
+- a) establish inbound RTP security based on its preferred (first) RTP ciphersuite and End-End  $Secret_0$ , as described in 7.6.2.3.3.1;
+- b) if connection mode allows, be ready to receive RTP packets, which may arrive any time after this message is sent by the  $MTA_0$ . If the list of ciphersuites for RTP was sent within a ModifyConnection command, the CMS may send an inactive directive to the MTA in the same command. The MTA should be returned to active status only when the new ciphersuite negotiation is complete.
+
+If the list of ciphersuites for RTCP contains at least one non-NULL encryption algorithm, before sending the response message,  $MTA_0$  must:
+
+- a) establish inbound RTCP security based on its preferred (first) RTCP ciphersuite and End-End  $Secret_0$ , as described in 7.6;
+- b) be ready to receive RTCP packets, which may arrive any time after this message is sent by  $MTA_0$ .
+
+If  $MTA_1$  decides to use an alternate ciphersuite listed by  $MTA_0$ ,  $MTA_0$  will later have to update its RTP and RTCP keys. If  $MTA_1$  decides to send  $MTA_0$  packets before ciphersuite negotiation had completed, processing on those packets at  $MTA_0$  will fail (since it assumed a different ciphersuite). If media stream security is disabled (AUTH\_NULL/RTP\_ENCR\_NULL ciphersuite list for RTP and RTCP\_AUTH\_NULL/RTCP\_ENCR\_NULL for RTCP),  $MTA_0$  will later have to discard its keys and send and receive RTP and RTCP packets without any security.
+
+###### 3) $CMS_0 \rightarrow CMS_1$
+
+$CMS_0$  must send End-End  $Secret_0$  (if included),  $Pad_1$  (if included) and the list of RTP and RTCP ciphersuites to  $CMS_1$  (local to  $MTA_1$ ) as selected by  $MTA_0$ .  $CMS_1$  will later forward this information to  $MTA_1$ . Note that End-End  $Secret_0$  and  $Pad_1$  will not be included if the
+
+RTP and RTCP ciphersuites lists both contain only the NULL authentication and NULL encryption combination.
+
+###### 4) $CMS_1 \rightarrow MTA_1$
+
+$CMS_1$  sends a CreateConnection to  $MTA_1$ .  $CMS_1$  may provide lists of approved RTP and RTCP ciphersuites, if the CMS has been configured to do so. The ciphersuites are provided in the order of preference specified by the operator subject to the constraints specified in 7.6.2.3.3.1. The RemoteConnectionDescriptor must be included in this CRCX command. It must contain End-End Secret<sub>0</sub> (if sent in step 3) and Pad<sub>1</sub> (if sent in step 3) received from  $MTA_0$  (via  $CMS_0$ ). It must also contain the ciphersuites preferred by  $MTA_0$ .
+
+###### 5) $MTA_1 \rightarrow CMS_1$
+
+$MTA_1$  has received a CRCX message that contains both LocalConnectionOptions and RemoteConnectionDescriptor parameters and must follow the ciphersuite negotiation procedure described above to negotiate RTP and RTCP ciphersuites. This list will consist of  $MTA_1$ 's allowed ciphersuites in the order of preference specified by  $CMS_1$  if the LocalConnectionOptions ciphersuites parameter is included in step 4. If RTP and RTCP ciphersuite negotiation succeeds and there is at least one RTP ciphersuite and at least one RTCP ciphersuite, then  $MTA_1$  returns the negotiated list of ciphersuites in the subsequent response message, in the LocalConnectionDescriptor parameter, in the form of SDP attributes. Note that if media stream security is being disabled, the NULL authentication and NULL encryption combination will be the only entry in both the RTP and RTCP ciphersuites lists. If RTP or RTCP ciphersuite negotiation fails,  $MTA_1$  must return an error code as specified above.
+
+In the event that  $MTA_1$  receives SDP in the RemoteConnectionDescriptor parameter without ciphersuites media attributes,  $MTA_1$  assumes that the lists of RTP and RTCP ciphersuites supported by the remote endpoint is RTP AUTH\_NULL/RTP\_ENCR\_NULL and RTCP\_AUTH\_NULL/RTCP\_ENCR\_NULL.
+
+If the RTP and RTCP ciphersuites provided do not adhere to the rules provided in 7.6.2.3.1.1, the MTA returns an error, e.g., 524 (Internal inconsistency in LocalConnectionOptions).
+
+Whenever possible,  $MTA_1$  SHOULD select the first supported ciphersuite for RTP and the first supported ciphersuite for RTCP in the RemoteConnectionDescriptor parameter. This allows  $MTA_1$  to immediately start sending RTP and RTCP packets to  $MTA_0$ .  $MTA_1$  MAY instead select alternate ciphersuites specified by  $MTA_0$ .
+
+$MTA_1$  returns a response message, which includes lists of the selected ciphersuites inside the LocalConnectionDescriptor parameter, in the form of SDP attributes. The first ciphersuite in each list (one for RTP and one for RTCP) must be the one that was selected by  $MTA_1$ . Additional ciphersuites in each list are alternatives in a prioritized order. If at any time  $MTA_0$  wants to switch to one of the alternatives that were selected by  $MTA_1$ , it would have to go through a new key negotiation. The response message must also include the ConnectionId (generated by  $MTA_1$ ) as specified in ITU-T Rec. J.162. Thus, both End-End Secret<sub>0</sub> and End-End Secret<sub>1</sub> are now associated with a pair (EndpointId, ConnectionId).
+
+If the lists of ciphersuites for RTP and RTCP contain at least one non-NULL selection each, then  $MTA_1$  must generate the End-End Secret<sub>1</sub> for the incoming RTP and RTCP packets, and return it along with the ciphersuite list in the LocalConnectionDescriptor. If the lists of ciphersuites for RTP and RTCP contain at least one non-NULL selection each,  $MTA_1$  should also generate Pad<sub>0</sub> and return it in the same LocalConnectionDescriptor parameter.
+
+Although the option of not generating Pad<sub>0</sub> is provided in order to better support early media flows from  $MTA_1$ , it results in  $MTA_1$  using a send key that is completely dependent
+
+on a random value generated by  $MTA_0$ . In other words, privacy of the media stream generated by  $MTA_1$  in this case depends on the strength of  $MTA_0$ 's random number generator.
+
+If the list of ciphersuites for RTP contains at least one non-NULL encryption or authentication algorithm, before sending the response message,  $MTA_1$  must:
+
+- a) establish inbound RTP security based on its selected RTP ciphersuite, End-End  $Secret_1$  and  $Pad_1$ , as described in 7.6.2.3.3.1;
+- b) establish outbound RTP security based on its selected RTP ciphersuite and End-End  $Secret_0$ , as described in 7.6.2.3.3.1. If  $Pad_0$  was generated by  $MTA_1$ , the outbound RTP security will also be based on  $Pad_0$ ;
+- c) if connection mode allows, be ready to receive RTP packets, which may arrive from  $MTA_0$  any time after this message is sent.
+
+If the list of ciphersuites for RTCP contains at least one non-NULL encryption or authentication algorithm, before sending the response message,  $MTA_1$  must:
+
+- a) establish inbound RTCP security based on its selected RTCP ciphersuite, End-End  $Secret_1$  and  $Pad_1$  as described in 7.6.2.3.3.1;
+- b) establish outbound RTCP security, based on its selected RTCP ciphersuite and End-End  $Secret_0$ , as described in 7.6.2.3.3.1. If  $Pad_0$  was generated by  $MTA_1$ , the outbound RTCP security will also be based on  $Pad_0$ ;
+- c) be ready to receive RTCP messages, which may arrive from  $MTA_0$  any time after this message is sent by.
+
+Any time after sending this response message to the  $CMS_1$ ,  $MTA_1$  may begin sending RTP and RTCP packets to  $MTA_0$ . However, in the case that  $MTA_1$  generated  $Pad_0$  or selected a different ciphersuite from the one preferred by  $MTA_0$ ,  $MTA_0$  will not be able to decrypt packets from  $MTA_1$ , until  $MTA_0$  has received  $MTA_1$ 's SDP.
+
+###### 6) $CMS_1 \rightarrow CMS_0$
+
+$CMS_1$  must forward the End-End  $Secret_1$  (if included),  $Pad_0$  (if included) and the selected ciphersuites sent from  $MTA_1$  to  $CMS_0$ . Note that End-End  $Secret_0$  and  $Pad_1$  will not be included if the RTP and RTCP ciphersuites lists both contain only the NULL authentication and NULL encryption algorithm combination.
+
+###### 7) $CMS_0 \rightarrow MTA_0$
+
+$CMS_0$  may send to  $MTA_0$  in the ModifyConnection (MDCX) command, inside the LocalConnectionOptions parameter, the lists of allowed RTP and RTCP ciphersuites. These ciphersuites should be what  $CMS_0$  policy allows. (The reason that  $CMS_0$  is not required to send the lists of ciphersuites is because it might have already sent them to  $MTA_0$  in a CreateConnection (CRCX) command.  $CMS_0$  would send the ciphersuites again for consistency.)
+
+In the event that  $MTA_0$  receives SDP in the RemoteConnectionDescriptor parameter without fields containing ciphersuites media attributes,  $MTA_0$  assumes that the RTP and RTCP ciphersuite lists supported by the remote endpoint are AUTH\_NULL/RTP\_ENCR\_NULL for RTP and RTCP\_AUTH\_NULL/RTCP\_ENCR\_NULL for RTCP.
+
+In the event that  $CMS_0$  received SDP from  $MTA_1$ , the RemoteConnectionDescriptor parameter must be included in this ModifyConnection command. If present, it must contain the RTP and RTCP ciphersuites (and alternatives) selected by  $MTA_1$ . If ciphersuites are included in LocalConnectionOptions parameter or a RemoteConnectionDescriptor parameter is included with the ModifyConnection command,  $MTA_0$  must perform ciphersuite negotiation as described above.
+
+If the RemoteConnectionDescriptor is not sent in this MDCX command, MTA<sub>0</sub> will still be able to receive RTP and RTCP messages but will be unable to send anything to MTA<sub>1</sub>.
+
+After receiving this message, MTA<sub>0</sub> must:
+
+- a) if Pad<sub>0</sub> was received, remove its inbound RTP keys and replace them with new ones, based on the keys that are generated from both End-End Secret<sub>0</sub> and Pad<sub>0</sub>. MTA<sub>0</sub> MUST re-initialize the RTP timestamp for the new keys. The ciphersuites used for these inbound keys are taken from the RemoteConnectionDescriptor just received from CMS<sub>0</sub>;
+- b) if Pad<sub>0</sub> was received, remove its inbound RTCP keys and replace them with new ones, based on the keys that are generated from both End-End Secret<sub>0</sub> and Pad<sub>0</sub>. Re-initialize RTCP sequence numbers for the new keys. The ciphersuites used for these inbound keys are taken from the RemoteConnectionDescriptor just received from CMS<sub>0</sub>;
+- c) if the RemoteConnectionDescriptor was received without Pad<sub>0</sub>, check if the first RTP ciphersuite in the RemoteConnectionDescriptor differs from the one that MTA<sub>0</sub> selected in step b. If they differ, perform the following steps:
+  - Remove the inbound RTP key.
+  - If the new RTP ciphersuite is non NULL, generate new inbound RTP keys and RTP timestamp from the same End-End Secret<sub>0</sub> as the last time, as specified in 7.6.2.3.3.1;
+- d) if the RemoteConnectionDescriptor parameter was received without Pad<sub>0</sub>, check if the first RTCP ciphersuite field in the RemoteConnectionDescriptor parameter differs from the one that MTA<sub>0</sub> selected in step b. If they differ, perform the following steps:
+  - Remove the inbound RTCP key.
+  - If the new RTCP ciphersuite is non NULL, generate a new key based on the key generated from the same End-End Secret<sub>0</sub> as the last time, but for the new authentication and/or encryption algorithms;
+- e) if the RemoteConnectionDescriptor parameter was received, establish outbound RTP keys, based on End-End Secret<sub>1</sub> and Pad<sub>1</sub>;
+- f) if the RemoteConnectionDescriptor parameter was received, establish outbound RTCP keys, based on End-End Secret<sub>1</sub> and Pad<sub>1</sub>;
+- g) be ready to send and receive RTCP messages with MTA<sub>1</sub>. If connection mode allows, be ready to send and receive RTP messages with MTA<sub>1</sub>.
+
+For the full syntax of the NCS messages, please refer to the NCS signalling Recommendation (ITU-T Rec. J.162).
+
+##### 7.6.2.3.2 Ciphersuite format
+
+Each ciphersuite for both RTP security and RTCP security MUST be represented as follows:
+
+|                                                                                                                    |                                                                                                                   |
+|--------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------|
+| <b>Authentication Algorithm</b> (1 byte) –<br>represented by 2 ASCII hex characters<br>(using characters 0-9, A-F) | <b>Encryption Transform ID</b> (1 byte) –<br>represented by 2 ASCII hex characters<br>(using characters 0-9, A-F) |
+|--------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------|
+
+For the list of available transforms and their values, refer to 6.6 for RTP security, and to 6.7 for RTCP security. For the exact syntax of how the Authentication Algorithm and the Encryption Transform ID are included in the signalling messages, refer to ITU-T Rec. J.162 for NCS.
+
+##### 7.6.2.3.3 Derivation of end-to-end keys
+
+###### 7.6.2.3.3.1 Initial key derivation
+
+The End-End Secrets MUST be 46 bytes long. The Pad parameters MUST be 46 bytes long.
+
+Keys are independently derived by each MTA from either just the End-End Secret or from the End-End Secret and Pad concatenated together. The Pad may or may not be available – see the call flow details specified in 7.6.2.3.1.
+
+The keys derived from one End-End Secret (and possibly a Pad) MUST be used to secure RTP and RTCP messages directed to only one of the MTAs. There is a separate End-End Secret and a separate Pad value for each direction, negotiated through NCS signalling. The keys MUST be derived as follows, in the specified order:
+
+- 1) RTP (media stream security). Derive a set of the following keys with the derivation function  $F(S, \text{"End-End RTP Security Association"})$ . Here,  $S$  is concatenation of the following binary values, each in MSB-first order:
+  - a) End-End Secret;
+  - b) Pad (optional, if it was negotiated through signalling).
+
+The string "End-End RTP Security Association" is taken without quotes and without a terminating null character. Function  $F$  (specified in 9.6) is used to recursively generate enough random bytes to produce all of the keys and other parameters that are specified below, in the listed order:
+
+- a) RTP privacy key.
+  - b) RTP Initial Timestamp (integer value, 4 octets, Big-Endian byte order).
+  - c) RTP Initialization Key (required when using a block cipher to encrypt the RTP payload). The length MUST be the same as the selected cipher's block size. This value is used to derive the IV according to 7.6.2.1.2.2. The resulting IV is used for the block cipher in CBC mode (if applicable) and for the random pad used to calculate the MMH MAC.
+  - d) RTP packet MAC key (if MAC option is selected). The requirements for the MMH MAC key can be found in 7.6.2.1.2.1.1
+- 2) RTCP security. Derive a set of the following keys in the specified order with the derivation function  $F(S, \text{"End-End RTCP Control Protocol Security Association"})$ . Here,  $S$  is concatenation of the following binary values:
+  - a) End-End Secret.
+  - b) Pad (optional, if it was negotiated through signalling).
+
+Function  $F$  (specified in 9.6) is used to recursively generate enough random bytes to produce all of the keys that are specified below, in the listed order:
+
+- a) RTCP authentication key.
+- b) RTCP encryption key.
+
+#### 7.6.2.4 RTP-RTCP summary security profile matrix
+
+**Table 27 – Security profile matrix – RTP and RTCP**
+
+|                     | <b>RTP (MTA-MTA,<br/>MTA-MG)</b>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | <b>RTCP (MTA-MTA,<br/>MTA-MG, MG-MG)</b>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+|---------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Authentication      | Optional (indirect) (Note)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     | Optional (indirect)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
+| Access control      | Optional                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | Optional                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+| Integrity           | Optional                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | Optional                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+| Confidentiality     | Optional                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       | Optional                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+| Non-repudiation     | No                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             | No                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
+| Security mechanisms | <p>Application Layer Security via RTP IPCablecom Security Profile</p> <p>End-to-End Secret distributed over secured MTA-CMS links. Final keys derived from this secret.</p> <p>AES-128 in CBC mode encryption algorithm</p> <p>Optional 2-byte or 4-byte MAC based on MMH algorithm.</p> <p>RTP encryption and authentication can be optionally turned off with the selection of NULL encryption and NULL authentication algorithms. RTP security and RTCP security are disabled together.</p> <p>IPCablecom requires support for ciphersuite negotiation.</p> | <p>RTCP messages are secured by RTCP application layer security mechanisms specified in the profile.</p> <p>RTCP ciphersuites are negotiated separately from the RTP ciphersuites and include both encryption and message authentication algorithms.</p> <p>RTCP encryption can be optionally turned off with the selection of a null encryption algorithm.</p> <p>Both RTCP encryption and authentication can be optionally turned off with the selection of NULL encryption and NULL authentication algorithms. RTCP security and RTP security are disabled together.</p> <p>Keys are derived from the End-End Secret using the same mechanism as used for RTP encryption.</p> |
+
+NOTE – MTAs do not authenticate directly. Authentication refers to the authentication of identity.
+
+## 7.7 Audio Server services
+
+### 7.7.1 Reference architecture
+
+Figure 21 shows the network components and the various interfaces to be discussed in this clause; see ITU-T Rec. J.175.
+
+![Figure 21: Audio Server components and interfaces. The diagram shows a network-based Media Player (MP) architecture. On the left, an MTA (Media Terminal Adapter) is connected to a CMS (Content Management System) via interface Ann-1. The MTA is also connected to a PSTN (Public Switched Telephone Network) via interface Ann-4. The CMS is connected to a Media Gateway Controller (MGC) via interface Ann-3. The MGC is connected to a Media Gateway (MG) via interface Ann-1. The MG is connected to the PSTN. The CMS is also connected to an Audio Server (AS) via interface Ann-3. The AS contains a Media Player Controller (MPC) and a Media Player (MP). The MPC is connected to the MP via interface Ann-2. The MTA is also connected to the MP via interface Ann-4. The diagram is labeled J.170_F21.](199607ec43a5b7ad43b1896e152e742b_img.jpg)
+
+```
+
+graph TD
+    subgraph AS [Audio Server AS]
+        MPC[Media Player Controller MPC]
+        MP[Media Player MP]
+        MPC --- Ann2[Ann-2] --- MP
+    end
+    MTA[MTA] --- Ann1[Ann-1] --- CMS[CMS]
+    MTA --- Ann4[Ann-4] --- MP
+    CMS --- Ann3[Ann-3] --- MPC
+    CMS --- Ann3[Ann-3] --- MGC[Media Gateway Controller MGC]
+    MGC --- Ann1[Ann-1] --- MG[Media Gateway MG]
+    MG --- PSTN((PSTN))
+    MTA --- Ann4[Ann-4] --- PSTN
+    style AS fill:none,stroke-dasharray: 5 5
+    style MG fill:none,stroke-dasharray: 5 5
+    style MGC fill:none,stroke-dasharray: 5 5
+    style PSTN fill:none,stroke:none
+  
+```
+
+Figure 21: Audio Server components and interfaces. The diagram shows a network-based Media Player (MP) architecture. On the left, an MTA (Media Terminal Adapter) is connected to a CMS (Content Management System) via interface Ann-1. The MTA is also connected to a PSTN (Public Switched Telephone Network) via interface Ann-4. The CMS is connected to a Media Gateway Controller (MGC) via interface Ann-3. The MGC is connected to a Media Gateway (MG) via interface Ann-1. The MG is connected to the PSTN. The CMS is also connected to an Audio Server (AS) via interface Ann-3. The AS contains a Media Player Controller (MPC) and a Media Player (MP). The MPC is connected to the MP via interface Ann-2. The MTA is also connected to the MP via interface Ann-4. The diagram is labeled J.170\_F21.
+
+**Figure 21 – Audio Server components and interfaces**
+
+Figure 21 shows a network-based Media Player (MP). It has an optional Audio Server Protocol (ASP) interface (Ann-2) to the Media Player Controller (MPC), in the case that MPC and MP are not integrated into a single physical entity. Security on this interface is specified in this clause.
+
+There is also an NCS signalling interface (Ann-1) between the MTA and CMS and between the Media Gateway Controller (MGC) and the Media Gateway (MG). Refer to 7.4.1 for NCS signalling security. There is also a signalling interface (Ann-3) between the CMS and the MPC and the CMS and the MGC. This interface is proprietary for IPCablecom, and thus the corresponding security interface is not specified (although this clause lists recommended security services for Ann-3).
+
+Finally, there is a media stream (RTP and RTCP) interface (Ann-4) between the MTA and the MP. This is a standard media stream interface, for which security is defined in 6.6.
+
+The Audio Server architecture also allows local playout of announcements at the MTA. In those cases, an announcement is initiated with NCS signalling between the MTA and the CMS (interface Ann-1). No other interfaces are needed for MTA-based announcement services.
+
+### 7.7.2 Security services
+
+#### 7.7.2.1 MTA-CMS NCS signalling (Ann-1)
+
+Refer to the security services in NCS signalling in 7.4.1.2.
+
+#### 7.7.2.2 MPC-MP Signalling (Ann-2)
+
+*Authentication:* All signalling messages must be authenticated, in order to prevent a third party masquerading as either an authorized MPC or MP. A rogue MPC could configure the MP to play obscene or inappropriate messages. A rogue MP could likewise play obscene or inappropriate messages that the MPC did not intend it to play. If MP is unable to authenticate to the MPC, the MPC should not pass it the key for media packets, preventing unauthorized announcement playout.
+
+*Confidentiality:* If a snooper is able to monitor ASP signalling messages on this interface, he or she might determine which services are used by a particular subscriber or which destinations a
+
+subscriber is communicating to. This information could then be sold for marketing purposes or simply used to spy on other subscribers. Thus, confidentiality is required on this interface.
+
+*Message integrity:* must be assured in order to prevent tampering with signalling messages. This could lead to playout of obscene or inappropriate messages – see authentication above.
+
+*Access control:* An MPC should keep a list of valid Media Players and which announcements each supports. Along with authentication, this ensures that wrong announcements are not played out.
+
+#### **7.7.2.3 MTA-MP (Ann-4)**
+
+Security services on this media packet interface are listed in 7.6.1.
+
+### **7.7.3 Cryptographic mechanisms**
+
+#### **7.7.3.1 MTA-CMS NCS signalling (Ann-1)**
+
+Refer to the cryptographic mechanisms in NCS signalling in 7.4.1.3.
+
+#### **7.7.3.2 MPC-MP signalling (Ann-2)**
+
+IPsec ESP MUST be used to both authenticate and encrypt the messages from MPC to MP and vice versa. Refer to 6.1 for details of how IPsec ESP is used within IPCablecom and for the list of available ciphersuites.
+
+#### **7.7.3.3 MTA-MP (Ann-4)**
+
+Cryptographic mechanisms on this media packet interface are specified in 7.6.2.
+
+### **7.7.4 Key management**
+
+#### **7.7.4.1 MTA-CMS NCS signalling (Ann-1)**
+
+Refer to the key management in NCS signalling in 7.4.1.
+
+#### **7.7.4.2 MPC-MP signalling (Ann-2)**
+
+The MPC and the MP negotiate a shared secret (MPC-MP Secret) using IKE or Kerberos (implementations MUST support IKE with pre-shared keys; they MAY support IKE with X.509 certificates and they MAY support Kerberos using symmetric keys). For more information on the use of IKE, refer to 6.2.2. For more information on the use of Kerberos with symmetric keys, refer to 6.4.3 and 6.5.
+
+The key management protocol MUST be running asynchronous to the signalling messages and will guarantee that there is always a valid, non-expired MPC-MP Secret. This shared secret MUST be unique to this particular MPC and MP.
+
+#### **7.7.4.3 MTA-MP (Ann-4)**
+
+Key management on the media packet interface is specified in 7.6.2.3. This case is very similar to the key management for the MTA-MG media interface. The flow of signalling messages and the syntax of carrying keys and ciphersuites MUST be the same, except that here MG is replaced with the MP and MGC (which delivers the key to MG) is replaced with MPC (which delivers the key to MP).
+
+### **7.7.5 MPC-MP summary security profile matrix**
+
+The CMS to MPC protocol is not defined in IPCablecom and thus is outside the scope of this Recommendation. The corresponding column in the matrix in Table 28 provides only the security requirements on that interface. Security specifications on that interface will be added in future revisions of this Recommendation.
+
+**Table 28 – Security profile matrix – Audio Server services**
+
+|                     | <b>Ann-1: NCS<br/>(MTA-CMS) &amp;<br/>(MG-MGC)</b>                                                                                                                                | <b>Ann-2:<br/>ASP<br/>(MPC-<br/>MP)</b> | <b>Ann-3:<br/>Unspecified<br/>(CMS-MPC) &amp;<br/>(CMS-MGC)<br/>interface security<br/>requirements<br/>(Note)</b> | <b>Ann-4: RTP<br/>(MTA-MP)</b>                                                                                                                                                                                   | <b>Ann-4:<br/>RTCP<br/>(MTA-MP)</b>                                                                                                                                                                |
+|---------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------|--------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Authentication      | Yes                                                                                                                                                                               | Yes                                     | Yes                                                                                                                | Yes (indirect)                                                                                                                                                                                                   | Yes (indirect)                                                                                                                                                                                     |
+| Access control      | Yes                                                                                                                                                                               | Yes                                     | Yes                                                                                                                | Optional                                                                                                                                                                                                         | Optional                                                                                                                                                                                           |
+| Integrity           | Yes                                                                                                                                                                               | Yes                                     | Yes                                                                                                                | Optional                                                                                                                                                                                                         | Yes                                                                                                                                                                                                |
+| Confidentiality     | Yes                                                                                                                                                                               | Yes                                     | Yes                                                                                                                | Yes                                                                                                                                                                                                              | Yes                                                                                                                                                                                                |
+| Non-repudiation     | No                                                                                                                                                                                | No                                      | No                                                                                                                 | No                                                                                                                                                                                                               | No                                                                                                                                                                                                 |
+| Security mechanisms | IPsec ESP in transport mode<br>Encryption and message integrity both enabled<br>Kerberos with PKINIT key management for MTA-CMS interface<br>IKE or Kerberos for MG-MGC interface | IPsec IKE or Kerberos                   |                                                                                                                    | Application Layer Security via RTP Packet Cable Security Profile keys distributed over secured MTA-CMS and MP-MPC links<br>AES-128 encryption algorithm<br>Optional 2-byte or 4-byte MAC based on MMH algorithm. | RTCP messages are secured by RTCP application layer security mechanisms specified in the profile.<br>Keys are derived from the End-End Secret using the same mechanism as used for RTP encryption. |
+
+NOTE – Although (CMS-MPC) is a proprietary interface, these are security requirements for the CMS-MPC interface.
+
+## 7.8 Electronic surveillance interfaces
+
+### 7.8.1 Reference architecture
+
+The IPCablecom system for electronic surveillance consists of elements and interfaces, as shown in Figure 22.
+
+![Diagram of electronic surveillance security interfaces showing elements CMS, CMS/MGC, CMTS, DF, and MG and their connections.](e2180bd000d9ae6dea6b38d1cc79755b_img.jpg)
+
+```
+
+graph TD
+    CMS[CMS] -- Signalling --> CMS/MGC[CMS/MGC]
+    CMS -- COPS --> CMTS[CMTS]
+    CMS -- Events --> DF1[DF]
+    CMS/MGC -- Events --> DF2[DF]
+    CMS/MGC -- TGCP --> MG[MG]
+    CMTS -- Events --> DF1
+    CMTS -- Content --> DF1
+    DF1 -- Events --> DF2
+    DF1 -- Content --> DF2
+    DF2 -- Content --> MG
+    
+```
+
+The diagram illustrates the reference architecture for electronic surveillance security interfaces. It features five main elements: CMS (Central Management System), CMS/MGC (CMS/Media Gateway Controller), CMTS (Cable Modem Termination System), DF (Distribution Function), and MG (Media Gateway). The CMS is connected to the CMS/MGC via a 'Signalling' interface. The CMS is also connected to the CMTS via a 'COPS' interface and to the first DF via 'Events'. The CMS/MGC is connected to the MG via a 'TGCP' interface and to the second DF via 'Events'. The CMTS is connected to the first DF via 'Events' and 'Content' interfaces. The first DF is connected to the second DF via 'Events' and 'Content' interfaces. The second DF is connected to the MG via a 'Content' interface. The label 'J.170\_F22' is present in the bottom right corner of the diagram.
+
+Diagram of electronic surveillance security interfaces showing elements CMS, CMS/MGC, CMTS, DF, and MG and their connections.
+
+**Figure 22 – Electronic surveillance security interfaces**
+
+The DF (Delivery Function) in Figure 22 is responsible for redirecting duplicated media packets to law enforcement, for the purpose of wiretapping.
+
+The event interface between the CMS or the MGC and the DF provides descriptions of calls, which is necessary to perform wiretapping. That information includes the media stream encryption key and the corresponding encryption algorithm. This event interface uses RADIUS and is similar to the CMS-RKS interface.
+
+The COPS interface between the CMS and the CMTS is used to signal the CMTS to start/stop duplicating media packets to the DF for a particular call. This is the same COPS interface that is used for (DQoS) Gate Authorization messages. For the corresponding security services, refer to 7.2.1.2.2, 7.2.1.3.2 and 7.2.1.4.1.
+
+The TGCP signalling interface between the MGC and MG is used to signal the MG to start/stop duplicating media packets to the DF for a particular call. This is the same TGCP signalling interface that is used during call set-up on the PSTN Gateway side. For the corresponding security services, refer to 7.8.2.1, 7.8.3.1 and 7.8.4.1.
+
+The event interface between the CMTS and DF is needed to tell the DF when the actual call begins and when it ends. In IPCablecom, the start and end of the actual call is signalled with RADIUS event messages generated by the CMTS.
+
+The interface between the CMTS and DF for call content is where the CMTS encapsulates copies of the RTP media packets – including the original IP header – inside UDP and forwards them to the DF. Since the original media packets are already encrypted (and optionally authenticated), no additional security is defined on this interface. Similarly, there is no additional security applied to the call content interface between the MG and DF: the MG simply encapsulates copies of the encrypted RTP packets inside UDP and forwards them to the DF.
+
+The event interface between the two DFs is used to forward call information in the case where a wiretapped call is forwarded to another location that is wiretapped using a different DF. This interface utilizes the RADIUS protocol – the same as all other event message interfaces.
+
+The interface between the two DFs for call content is used to forward media packets (including the original IP header) in the case where a wiretapped call is forwarded to another location that is wiretapped using a different DF. Since the original media packets are already encrypted (and optionally authenticated), no additional security is defined on this interface.
+
+### 7.8.2 Security services
+
+#### 7.8.2.1 Event interfaces CMS-DF, MGC-DF, CMTS-DF and DF-DF
+
+*Authentication, Access control and Message integrity:* required to prevent service theft and denial-of-service attacks. There is a need to ensure that the DF (law enforcement) has the right parameters for wiretapping (prevent denial-of-service). Also, there is a need to authenticate the DF, to make sure that the copy of the media stream is directed to the right place (protect privacy).
+
+*Confidentiality:* required to protect subscriber information and communication patterns.
+
+#### 7.8.2.2 Call content interfaces CMTS-DF, MG-DF and DF-DF
+
+*Authentication and Access control:* already performed during the phase of key management for protection of event messages – see the above clause. In order to protect privacy, a party that is not properly authorized should not receive the call content decryption key.
+
+*Message integrity:* optional for voice packets, since it is generally hard to make undetected changes to voice packets. No additional security is required here – an optional integrity check would be placed into the media packets by the source (MTA or MG).
+
+*Confidentiality:* required to protect call content from unauthorized snooping.
+
+However, no additional security is required in this case – the packets had been previously encrypted by the source (MTA or MG).
+
+### **7.8.3 Cryptographic mechanisms**
+
+#### **7.8.3.1 Interface between CMS and DF**
+
+This interface MUST be protected with IPsec ESP in transport mode, where each packet is both encrypted and authenticated – identical to the security for the CMS-RKS interface specified in 7.3.3.1.
+
+As with the CMS-RKS interface, the MAC value normally used to authenticate RADIUS messages is not used (message integrity is provided with IPsec). The key for this RADIUS MAC MUST always be hardcoded to 16 ASCII 0s.
+
+#### **7.8.3.2 Interface between CMTS and DF for Event Messages**
+
+This interface MUST be protected with IPsec ESP in transport mode, where each packet is both encrypted and authenticated – identical to the security for the CMTS-RKS interface specified in 7.3.3.2.
+
+As with the CMTS-RKS interface, the MAC value normally used to authenticate RADIUS messages is not used (message integrity is provided with IPsec). The key for this RADIUS MAC MUST always be hardcoded to 16 ASCII 0s.
+
+#### **7.8.3.3 Interface between DF and DF for event messages**
+
+This interface MUST be protected with IPsec ESP in transport mode, where each packet is both encrypted and authenticated – identical to the security for the CMS-RKS interface specified in 7.3.3.1.
+
+As with the CMS-RKS interface, the MAC value normally used to authenticate RADIUS messages is not used (message integrity is provided with IPsec). The key for this RADIUS MAC MUST always be hardcoded to 16 ASCII 0s.
+
+#### **7.8.3.4 Interface between MGC and DF**
+
+This interface MUST be protected with IPsec ESP in transport mode, where each packet is both encrypted and authenticated – identical to the security for the MGC-RKS interface specified in 7.3.3.3.
+
+As with the MGC-RKS interface, the MAC value normally used to authenticate RADIUS messages is not used (message integrity is provided by IPsec). The key for this RADIUS MAC MUST always be hardcoded to 16 ASCII 0s.
+
+### **7.8.4 Key management**
+
+#### **7.8.4.1 Interface between CMS and DF**
+
+CMS and DF MUST negotiate a pair of IPsec SAs (inbound and outbound) using IKE or Kerberos (implementations MUST support IKE with pre-shared keys; they MAY support IKE with X.509 certificates and they MAY support Kerberos using symmetric keys).
+
+#### **7.8.4.2 Interface between CMTS and DF**
+
+The CMTS and the DF MUST negotiate a pair of SAs (inbound and outbound) using IKE or Kerberos (implementations MUST support IKE with pre-shared keys; they MAY support IKE with X.509 certificates and they MAY support Kerberos using symmetric keys).
+
+The key management protocol will be running asynchronous to the event message generation and will guarantee that there is always a valid, non-expired pair of SAs.
+
+#### 7.8.4.3 Interface between DF and DF
+
+The two DF hosts MUST negotiate a shared secret (DF-DF Secret) using IKE with certificates. The IPCablecom profile for IKE with certificates is specified in 6.2.2. IKE will be running asynchronous to the event message generation. In the case where an event message needs to be sent to a DF with which there is not a valid SA, the IPsec layer MUST automatically signal IKE to proceed with the key management exchanges and build a pair of IPsec SAs (inbound and outbound).
+
+Not all interfaces between the same pair of DFs will require IPsec. For example, the call content interface does not run over IPsec. In order for the IPsec SAs to be established only for the DF-DF event message interface, each DF MUST allocate a set of UDP ports on which it will both send and receive DF-DF event messages. IPsec policy database for each DF MUST specify either an enumeration or a range of local UDP ports for which IPsec is enabled and which will be used exclusively for DF-DF event messages. If there are multiple calls that are simultaneously wiretapped and forwarded between the same pair of DFs (on different UDP ports) – they MUST all be protected with a single pair of IPsec SAs (inbound-outbound). Whenever a DF attempts to send on one of those UDP ports, it will either use an existing IPsec SA for a particular destination DF, or it will trigger IKE to establish a pair of SAs (inbound-outbound) for the specific target DF. When the CMS tells a DF to forward event messages to another DF, it specifies the destination DF with an IP address. This means that the DF identity that needs authentication during an IKE exchange is the IP address. An IKE certificate for a DF contains the IP address of that DF. This IP address in the certificate MUST be used by IKE to validate the DF's IP address – to prevent IP address spoofing attacks.
+
+After a pair of DF-DF SAs has been idle for some period of time, a DF MAY decide to remove it. In this case, the DF MUST send an ISAKMP Delete message to the other DF – to notify the other side of the SA deletion. Upon receiving a Delete message, the other DF MUST also remove that pair of SAs.
+
+It will still be possible (with very small probability) that a DF uses an IPsec SA to send an event message to another DF; but when the event message arrives, the target DF has already deleted the corresponding SA and has to drop the message. If there is still a problem after several timeouts and retries (e.g., ISAKMP Delete message was lost in transit), the sending DF MUST remove all of the corresponding IPsec SAs and re-run IKE to set up new SAs.
+
+#### 7.8.4.4 Interface between MGC and DF
+
+MGC and the DF MUST negotiate a pair of IPsec SAs (inbound and outbound) using IKE with pre-shared keys.
+
+IKE will be running asynchronous to the event message generation and will guarantee that there is always a valid, non-expired pair of SAs.
+
+At the DF, MGC Element IDs MUST somehow be associated with the corresponding IP addresses. One possibility is to associate each pre-shared key directly with the Element ID. IKE negotiations will use an ISAKMP identity payload of type ID\_KEY\_ID to identify the pre-shared key. The value in that identity payload will be the Element ID used in event messages.
+
+Later, when an event message arrives at the DF, it will be able to query the database of SAs and retrieve a source IP address, based on the Element ID. The DF will make sure that it is the same as the source IP address in the IP packet header. One way to query this database is through SNMP, using an IPsec MIB.
+
+### 7.8.5 Electronic surveillance security profile matrix
+
+Table 29 – Security profile matrix – Electronic surveillance
+
+|                     | CMS-DF events,<br>MGC-DF events &<br>CMTS-DF events                                      | DF-DF events                                                                                   | CMTS-DF content &<br>MG-DF content                                            | DF-DF content                                                                 |
+|---------------------|------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------|-------------------------------------------------------------------------------|
+| Authentication      | Yes                                                                                      | Yes                                                                                            | Yes (indirect)                                                                | Yes (indirect)                                                                |
+| Access control      | Yes                                                                                      | Yes                                                                                            | Optional                                                                      | Optional                                                                      |
+| Integrity           | Yes                                                                                      | Yes                                                                                            | Optional                                                                      | Optional                                                                      |
+| Confidentiality     | Yes                                                                                      | Yes                                                                                            | Yes                                                                           | Yes                                                                           |
+| Non-repudiation     | No                                                                                       | No                                                                                             | No                                                                            | No                                                                            |
+| Security mechanisms | IPsec with encryption and message integrity enabled<br>Key management is IKE or Kerberos | IPsec with encryption and message integrity enabled<br>Key management is IKE with certificates | RTP packets are already encrypted and authenticated by the source (MTA or MG) | RTP packets are already encrypted and authenticated by the source (MTA or MG) |
+
+## 7.9 CMS provisioning
+
+### 7.9.1 Reference Architecture
+
+Provisioning is defined as the operations necessary to provide a specified service to a customer. IPCablecom service provisioning can be viewed as two distinct operations: MTA provisioning and CMS subscriber provisioning. CMS provisioning refers to the interface between the Provisioning Server and the CMS.
+
+### 7.9.2 Security Services
+
+*Authentication:* provisioning Server needs to be authenticated to prevent a third party from masquerading as a provisioning server to enable services for unauthorized MTAs. CMS needs to be authenticated to prevent someone from impersonating the CMS to receiving provisioning messages, thereby compromising privacy and deny service to provisioned MTAs.
+
+*Access Control:* required along with authentication to prevent unauthorized access to provisioning data as well as denial-of-service.
+
+*Integrity:* must be assured to disallow tampering with provisioning messages, in order to prevent a class of denial-of-service attacks.
+
+*Confidentiality:* provisioning messages contains private customer information, thus confidentiality is required.
+
+### 7.9.3 Cryptographic mechanisms
+
+IPsec ESP MUST be used to both authenticate and encrypt the messages from CMS to Provisioning Server and vice versa. Refer to 6.1.2 for details of how IPsec ESP is used within IPCablecom and for the list of available ciphersuites.
+
+### 7.9.4 Key management
+
+Key management for the CMS-Provisioning Server interface is either IKE or Kerberos. Implementations MUST support IKE with pre-shared keys. Implementations MAY support IKE with X.509 certificates and they MAY support Kerberos using symmetric keys. For more information on the IPCablecom use of IKE, refer to 6.2.2. For more information on the IPCablecom use of Kerberos with symmetric keys, refer to 6.4.3 and 6.5
+
+### 7.9.5 Provisioning Server – CMS summary security profile matrix
+
+**Table 30 – Security profile matrix – CMS provisioning**
+
+|                     | CMS-Provisioning Server  |
+|---------------------|--------------------------|
+| Authentication      | Yes                      |
+| Access control      | Yes                      |
+| Integrity           | Yes                      |
+| Confidentiality     | Yes                      |
+| Non-repudiation     | No                       |
+| Security mechanisms | IPsec<br>IKE or Kerberos |
+
+# 8 IPCablecom certificates
+
+IP Cablecom uses digital certificates, which comply with ITU-T Rec. X.509 and RFC 2459.
+
+## 8.1 Generic structure
+
+### 8.1.1 Version
+
+The version of the certificates MUST be v3. All certificates MUST comply with RFC 2459 except where the non-compliance with the RFC is explicitly stated in this clause.
+
+### 8.1.2 Public Key type
+
+RSA Public Keys are used throughout the hierarchy. The subjectPublicKeyInfo.algorithm.algorithm Object Identifier (OID) used MUST be 1.2.840.113549.1.1.1 (rsaEncryption).
+
+The public exponent for all RSA IPCablecom keys MUST be F4 – 65537.
+
+### 8.1.3 Extensions
+
+The following four extension MUST be used as specified in the subclauses below. Any other certificate extensions MAY also be included, but must be marked as non-critical.
+
+#### 8.1.3.1 subjectKeyIdentifier
+
+The subjectKeyIdentifier extension included in all IPCablecom CA certificates as required by RFC 2459 (e.g., all certificates except the device and ancillary certificates) MUST include the keyIdentifier value composed of the 160-bit SHA-1 hash of the value of the BIT STRING subjectPublicKey (excluding the tag, length and number of unused bits from the ASN.1 encoding) (see RFC 2459).
+
+#### 8.1.3.2 authorityKeyIdentifier
+
+The authorityKeyIdentifier extension MUST be included in all IPCablecom certificates with the exception of root certificates, and MUST include a keyIdentifier value that is identical to the subjectKeyIdentifier in the CA certificate.
+
+#### 8.1.3.3 keyUsage
+
+The keyUsage extension MUST be used for all IPCablecom CA certificates and MUST be marked as critical with a value of keyCertSign and cRLSign. A KeyUsage extension MAY be included in end-entity certificates and SHOULD be marked as critical if included as specified in RFC 2459.
+
+#### 8.1.3.4 basicConstraints
+
+The basicConstraints extension MUST be used for all IPCablecom CA certificates and MUST be marked as critical. The values for each certificate for basicConstraints MUST be marked as specified in each of the certificate description tables.
+
+### 8.1.4 Signature algorithm
+
+The signature mechanism used MUST be SHA-1 with RSA encryption. The specific OID is 1.2.840.113549.1.1.5.
+
+### 8.1.5 SubjectName and IssuerName
+
+If a string cannot be encoded as a PrintableString, it MUST be encoded as a UTF8String (tag [UNIVERSAL 12]).
+
+When encoding an X.500 Name:
+
+- 1) each RelativeDistinguishedName (RDN) MUST contain only a single element in the set of X.500 attributes;
+- 2) the order of the RDNs in an X.500 name MUST be the same as the order in which they are presented in this Recommendation.
+
+It should be noted that ITU-T Rec. X.509 and RFC 2459 define constraints (i.e., upper bounds) on the length of the attribute values. For example, the maximum length for common name (CN), organization name (O) and organizational unit (OU) name values is 64 characters. Where this Recommendation mandates the inclusion of a static string in one of these values (i.e., CN=<Company> System Operator CA), companies MUST ensure that the addition of their identifying information does not cause the total length of the value to exceed the upper bound. In the case where a company's name causes the length of the value to exceed the upper bound, the vendor MUST truncate or abbreviate their information to ensure the total length does not exceed the upper bound.
+
+### 8.1.6 Certificate profile notation
+
+The tables below use the following notation:
+
+- Extension details are specified by [c:critical, n:non-critical; m:mandatory, o:optional].
+- Optional subject naming attributes are surrounded by square brackets (e.g., [L = <city>]).
+- Variable naming attribute values are surrounded by angle brackets. (e.g., CN = <Company Name> IPCablecom CA). Values not surrounded by angle brackets are static and cannot be modified.
+
+## 8.2 Certificate trust hierarchy
+
+There are two distinct certificate hierarchies used in IPCablecom: the MTA Device Certificate Hierarchy and the IPCablecom Telephony Certificate Hierarchy (see Figure 23).
+
+![Figure 23 – IPCablecom certificate hierarchy. The diagram shows two certificate hierarchies. The left hierarchy, 'MTA device hierarchy', consists of three stacked boxes: 'MTA Root' at the top, 'MTA Manufacturer' in the middle, and 'MTA' at the bottom. The right hierarchy, 'IPCablecom telephony hierarchy', consists of 'IP Telephony Root' at the top, 'Telephony Service Provider' in the middle, and a dashed box labeled 'Local System Operator' below it. From the bottom of the 'Local System Operator' box, two lines branch out to two separate boxes at the bottom: 'KDC' on the left and 'DF' on the right. The label 'J.170_F23' is located at the bottom right of the diagram.](beda549cc2a4e2b9ac7f74fe9ed72b67_img.jpg)
+
+Figure 23 – IPCablecom certificate hierarchy. The diagram shows two certificate hierarchies. The left hierarchy, 'MTA device hierarchy', consists of three stacked boxes: 'MTA Root' at the top, 'MTA Manufacturer' in the middle, and 'MTA' at the bottom. The right hierarchy, 'IPCablecom telephony hierarchy', consists of 'IP Telephony Root' at the top, 'Telephony Service Provider' in the middle, and a dashed box labeled 'Local System Operator' below it. From the bottom of the 'Local System Operator' box, two lines branch out to two separate boxes at the bottom: 'KDC' on the left and 'DF' on the right. The label 'J.170\_F23' is located at the bottom right of the diagram.
+
+**Figure 23 – IPCablecom certificate hierarchy**
+
+### 8.2.1 Certificate validation
+
+Within IPCablecom, certificate validation, in general, involves validation of a whole chain of certificates. As an example, when the Provisioning Server validates an MTA Device Certificate, the actual chain of three certificates is validated:
+
+MTA Root Certificate + MTA Manufacturer Certificate + MTA Device Certificate
+
+The signature on the MTA Manufacturer Certificate is verified with the MTA Root Certificate and the signature on the MTA Device Certificate is verified with the MTA Manufacturer Certificate. The MTA Root Certificate is self-signed and is known in advance to the Provisioning Server. The public key present in the MTA Root Certificate is used to validate the signature on this same certificate.
+
+Usually, the first certificate in the chain is not explicitly included in the certificate chain that is sent over the wire. In the cases where the first certificate is explicitly included it **MUST** already be known to the verifying party ahead of time and **MUST NOT** contain any changes to the certificate with the possible exception of the certificate serial number, validity period and the value of the signature. If changes other than the certificate serial number, validity period and the value of the signature, exist in the IP Telephony Root certificate that was passed over the wire in comparison to the known IP Telephony Root certificate, the device making the comparison **MUST** fail the certificate verification.
+
+The exact rules for certificate chain validation must fully comply with RFC 2459, where they are referred to as "Certificate Path Validation". In general, X.509 certificates support a liberal set of rules for determining if the issuer name of a certificate matches the subject name of another. The rules are such that two name fields may be declared to match even though a binary comparison of the two name fields does not indicate a match. RFC 2459 recommends that certificate authorities restrict the encoding of name fields so that an implementation can declare a match or mismatch using simple binary comparison. IPCablecom security follows this recommendation. Accordingly, the DER-encoded `tbsCertificate.issuer` field of an IPCablecom certificate **MUST** be an exact match to the DER-encoded `tbsCertificate.subject` field of its issuer certificate. An implementation **MAY** compare an issuer name to a subject name by performing a binary comparison of the DER-encoded `tbsCertificate.issuer` and `tbsCertificate.subject` fields.
+
+The clauses below specify the required certificate chain, which must be used to verify each certificate that appears at the leaf node (i.e., at the bottom) in the IPCablecom certificate trust hierarchy illustrated in Figure 23.
+
+Validity period nesting is not checked and intentionally not enforced. Thus, the validity period of a certificate need not fall within the validity period of the certificate that issued it.
+
+### 8.2.2 MTA Device certificate hierarchy
+
+The device certificate hierarchy is rooted in an IPCablecom MTA Root certificate, which is used as the issuing certificate of a set of manufacturer's certificates. The manufacturer's certificates are used to sign the individual device certificates.
+
+The information contained in Table 31 contains the IPCablecom specific values for the required fields according to RFC 2459. These IPCablecom specific values MUST be followed according to Table 31, except that Validity Periods SHOULD be as given in the tables. If a required field is not specifically listed for IPCablecom, then the guidelines in RFC 2459 MUST be followed.
+
+#### 8.2.2.1 MTA Root Certificate
+
+This certificate MUST be verified as part of a certificate chain containing the MTA Root Certificate, MTA Manufacturer Certificate and the MTA Device Certificate.
+
+**Table 31 – MTA Root Certificate**
+
+|                   |                                                                                                                                                                                          |
+|-------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Subject name form | C=US, O=CableLabs, OU=PacketCable, CN=PacketCable Root Device Certificate Authority                                                                                                      |
+| Intended usage    | This certificate is used to sign MTA Manufacturer Certificates and is used by the Provisioning Server. This certificate is not used by the MTAs and thus does not appear in the MTA MIB. |
+| Signed by         | Self-signed                                                                                                                                                                              |
+| Validity period   | 20+ years. It is intended that the validity period be long enough so that this certificate is never re-issued.                                                                           |
+| Modulus length    | 2048                                                                                                                                                                                     |
+| Extensions        | KeyUsage[c,m](keyCertSign, cRLSign), subjectKeyIdentifier, basicConstraints[c,m](cA=true, pathLenConstraint=1)                                                                           |
+
+#### 8.2.2.2 MTA Manufacturer Certificate
+
+This certificate MUST be verified as part of a certificate chain containing the MTA Root Certificate, MTA Manufacturer Certificate (see Table 32) and the MTA Device Certificate.
+
+The state/province, city and manufacturer's facility are optional attributes. A manufacturer may have more than one manufacturer's certificate, and there may exist one or more certificates per manufacturer. All certificates for the same manufacturer MUST be provided to each MTA either at manufacture time or during a field update. The MTA MUST select an appropriate certificate for its use by matching the issuer name in the MTA Device Certificate with the subject name in the MTA Manufacturer Certificate. If present, the authorityKeyIdentifier of the device certificate MUST be matched to the subjectKeyIdentifier of the manufacturer certificate as described in RFC 2459.
+
+The <CompanyName> field that is present in O and CN MAY be different in the two instances.
+
+**Table 32 – MTA Manufacturer Certificate**
+
+|                   |                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+|-------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Subject name form | C=<country>, O=<CompanyName>, [S=<state/province>], [L=<city>],<br>OU=PacketCable, [OU=<Manufacturer's Facility>], CN=<CompanyName><br>PacketCable CA                                                                                                                                                                                                                                                                              |
+| Intended usage    | This certificate is issued to each MTA manufacturer and can be provided to each MTA as part of the secure code download as specified by this Recommendation (either at manufacture time, or during a field update). This certificate appears as a read-only parameter in the MTA MIB.<br>This certificate along with the MTA Device Certificate is used to authenticate the MTA device identity (MAC address) during provisioning. |
+| Signed by         | MTA Root Certificate CA                                                                                                                                                                                                                                                                                                                                                                                                            |
+| Validity period   | 20 years                                                                                                                                                                                                                                                                                                                                                                                                                           |
+| Modulus length    | 2048                                                                                                                                                                                                                                                                                                                                                                                                                               |
+| Extensions        | keyUsage[c,m](keyCertSign, cRLSign), subjectKeyIdentifier,<br>authorityKeyIdentifier basicConstraints[c,m](cA=true, pathLenConstraint=0)                                                                                                                                                                                                                                                                                           |
+
+#### **8.2.2.3 MTA Device Certificate**
+
+This certificate MUST be verified as part of a certificate chain containing the MTA Root Certificate, MTA Manufacturer Certificate and the MTA Device Certificate (see Table 33).
+
+The state/province, city and manufacturer's facility are optional attributes. The Manufacturer's Facility OU field, (if present) MAY be different from the Manufacturer's Facility OU field (if present) in the MTA Manufacturer certificate.
+
+The MAC address MUST be expressed as six pairs of hexadecimal digits separated by colons, e.g., "00:60:21:A5:0A:23". The alpha hex characters (A-F) MUST be expressed as uppercase letters.
+
+The MTA device certificate should not be replaced or renewed.
+
+**Table 33 – MTA Device Certificate**
+
+|                   |                                                                                                                                                                                                                                                                                                                   |
+|-------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Subject name form | C=<country>, O=<Company Name>, [S=<state/province>], [L=<city>],<br>OU=PacketCable, [OU=<Product Name>], [OU=<Manufacturer's Facility>],<br>CN=<MAC Address>                                                                                                                                                      |
+| Intended usage    | This certificate is issued by the MTA manufacturer and installed in the factory. The provisioning server cannot update this certificate. This certificate appears as a read-only parameter in the MTA MIB.<br>This certificate is used to authenticate the MTA device identity (MAC address) during provisioning. |
+| Signed by         | MTA Manufacturer Certificate CA                                                                                                                                                                                                                                                                                   |
+| Validity period   | At least 20 years                                                                                                                                                                                                                                                                                                 |
+| Modulus length    | 1024, 1536 or 2048                                                                                                                                                                                                                                                                                                |
+| Extensions        | keyUsage[n,o](digitalSignature, keyEncipherment),<br>authorityKeyIdentifier[n,m](keyIdentifier=<subjectKeyIdentifier value from CA certificate>)                                                                                                                                                                  |
+
+### **8.2.3 IPCablecom Telephony Certificate Hierarchy**
+
+The Service Provider Certificate Hierarchy is rooted in an IP Telephony Root certificate. That certificate is used as the issuing certificate of a set of service provider's certificates. The service provider's certificates are used to sign an optional local system certificate. If the local system
+
+certificate exists, then that is used to sign the ancillary equipment certificates; otherwise, the ancillary certificates are signed by the Service Provider's CA.
+
+The information contained in Table 34 contains the IPCablecom specific values for the required fields according to RFC 2459. These IPCablecom specific values **MUST** be followed according to Table 34 except that Validity Periods **SHOULD** be as given in the tables. If a required field is not specifically listed for IPCablecom, then the guidelines in RFC 2459 **MUST** be followed.
+
+#### 8.2.3.1 IP Telephony Root Certificate
+
+Before any Kerberos key management can be performed, an MTA and a KDC need to perform mutual authentication using the PKINIT extension to the Kerberos protocol. An MTA authenticates a KDC after it receives a PKINIT Reply message containing a KDC certificate chain. In authenticating the KDC, the MTA verifies the KDC certificate chain, including KDC's Service Provider Certificate signed by the IP Telephony Root CA.
+
+**Table 34 – IP Telephony Root Certificate**
+
+|                   |                                                                                                                                                                                                                                                                                                                                                              |
+|-------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Subject name form | C=US, O=CableLabs, OU=PacketCable, CN=PacketCable Root IP Telephony Certificate Authority                                                                                                                                                                                                                                                                    |
+| Intended usage    | This certificate is used to sign Telephony Service Provider certificates. This certificate is installed into each MTA at the time of manufacture or with a secure code download as specified by this Recommendation and cannot be updated by the Provisioning Server. Neither this root certificate nor the corresponding public key appears in the MTA MIB. |
+| Signed by         | Self-signed                                                                                                                                                                                                                                                                                                                                                  |
+| Validity period   | 20+ years. It is intended that the validity period be long enough so that this certificate is never re-issued.                                                                                                                                                                                                                                               |
+| Modulus length    | 2048                                                                                                                                                                                                                                                                                                                                                         |
+| Extensions        | keyUsage[c,m](keyCertSign, cRLSign), subjectKeyIdentifier, basicConstraints[c,m](cA=true, pathLenConstraint=2)                                                                                                                                                                                                                                               |
+
+#### 8.2.3.2 Telephony Service Provider Certificate
+
+This is the certificate (see Table 35) held by the telephony service provider, signed by the IP Telephony Root CA. It is verified as part of a certificate chain that includes the IP Telephony Root Certificate, Telephony Service Provider Certificate, optional Local System Certificate and an end-entity server certificate. The authenticating entities normally already possess the IP Telephony Root Certificate and it is not transmitted with the rest of the certificate chain.
+
+The fact that a Telephony Service Provider CA Certificate is always explicitly included in the certificate chain allows a Service Provider the flexibility to change its certificate without requiring re-configuration of each entity that validates this certificate chain (e.g., MTA validating a PKINIT Reply). Each time the Service Provider CA Certificate changes, its signature **MUST** be verified with the IP Telephony Root Certificate. However, a new certificate for the same Service Provider **MUST** preserve the same value of the OrganizationName attribute in the SubjectName.
+
+The <Company> field that is present in O and CN **MAY** be different in the two instances.
+
+**Table 35 – Telephony Service Provider Certificate**
+
+|                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
+|-------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Subject name form | C=<country>, O=<Company>, OU=PacketCable, CN=<Company> PacketCable System Operator CA                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |
+| Intended usage    | <p>This certificate corresponds to a top-level Certification Authority within a domain of a single Service Provider. In order to make it easy to update this certificate, each network element is configured with the OrganizationName attribute of the Service Provider Certificate SubjectName. This is the only attribute in the certificate that must remain constant.</p> <p>In the case of an MTA, there is a read-write parameter in the MIB that identifies the OrganizationName attribute for each Kerberos realm (that may be shared among multiple MTA endpoints). The MTA does not accept Service Provider certificates that do not match this value of the OrganizationName attribute in the SubjectName.</p> <p>An MTA needs to perform the first PKINIT exchange with the MSO KDC right after a reboot, at which time its MIB tables are not yet configured. At that time, the MTA MUST accept any Service Provider OrganizationName attribute, but it MUST later check that the value added into the MIB for this realm is the same as the one in the initial PKINIT Reply.</p> |
+| Signed by         | Signed by IP Telephony Root Certificate                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+| Validity period   | 20 years                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
+| Modulus length    | 2048                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
+| Extensions        | keyUsage[c,m](keyCertSign, cRLSign), subjectKeyIdentifier[n,m], authorityKeyIdentifier[n,m](keyIdentifier=<subjectKeyIdentifier value from CA certificate>), basicConstraints[c,m](cA=true, pathLenConstraint=1)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
+
+#### **8.2.3.3 Local System CA Certificate**
+
+This is the certificate (see Table 36) held by the local system. The existence of this certificate is optional, as the Telephony Service Provider CA may be used to directly sign all network server end-entity certificates. A certificate chain with a Local System Certificate MUST consist of the IP Telephony Root CA Certificate, Service Provider CA Certificate, Local System CA Certificate and an end-entity certificate.
+
+The <Company> field that is present in O and CN MAY be different in the two instances.
+
+**Table 36 – Local System Certificate**
+
+|                   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
+|-------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Subject name form | C=<Country>, O=<Company>, OU=PacketCable, OU=<Local System Name>, CN=<Company> PacketCable Local System CA                                                                                                                                                                                                                                                                                                                                                                               |
+| Intended usage    | <p>Telephony Service Provider CA may delegate the issuance of certificates to a regional Certification Authority called Local System CA (with the corresponding Local System Certificate).</p> <p>Network servers are allowed to move freely between regional Certification Authorities of the same Service Provider. Therefore, the MTA MIB does not contain any information regarding a Local System Certificate (which might restrict an MTA to KDCs within a particular region).</p> |
+| Signed by         | Telephony Service Provider Certificate                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
+| Validity period   | 20 years                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
+| Modulus length    | 1024, 1536, 2048                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+| Extensions        | keyUsage[c,m](keyCertSign, cRLSign), subjectKeyIdentifier-[n,m], authorityKeyIdentifier-[n,m](keyIdentifier=<subjectKeyIdentifier value from CA certificate>), basicConstraints[c,m](cA=true, pathLenConstraint=0)                                                                                                                                                                                                                                                                       |
+
+#### 8.2.3.4 Operational ancillary certificates
+
+All of these are signed by either the Local System CA or by the Telephony Service Provider CA. Other ancillary certificates may be added to this Recommendation at a later time.
+
+##### 8.2.3.4.1 Key Distribution Centre Certificate
+
+This certificate (see Table 37) MUST be verified as part of a certificate chain containing the IP Telephony Root Certificate, Service Provider Certificate and the Ancillary Device Certificates.
+
+The PKINIT specification in IETF RFC 4556 requires the KDC certificate to include the subjectAltName v3 certificate extension, the value of which must be the Kerberos principal name of the KDC.
+
+**Table 37 – Key Distribution Centre Certificate**
+
+|                   |                                                                                                                                                                                                                                                              |
+|-------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Subject name form | C=<Country>, O=<Company>, OU=PacketCable, OU=[<Local System Name>], OU= Key Distribution Center, CN=<DNS Name>                                                                                                                                               |
+| Intended usage    | To authenticate the identity of the KDC server to the MTA during PKINIT exchanges. This certificate is passed to the MTA inside the PKINIT replies and is therefore not included in the MTA MIB and cannot be updated or queried by the Provisioning Server. |
+| Signed by         | Telephony Service Provider Certificate or Local System Certificate                                                                                                                                                                                           |
+| Validity period   | 20 years                                                                                                                                                                                                                                                     |
+| Modulus length    | 1024, 1536 or 2048                                                                                                                                                                                                                                           |
+| Extensions        | keyUsage[n,o](digitalSignature), authorityKeyIdentifier<br>The keyUsage tag is optional. When it is used it SHOULD be marked as critical.<br>subjectAltName[n,m](see PKINIT Spec)                                                                            |
+
+##### 8.2.3.4.2 Delivery Function (DF) Certificate
+
+This certificate (see Table 38) MUST be verified as part of a certificate chain containing the IP Telephony Root Certificate, Service Provider Certificate and the Ancillary Device Certificates.
+
+This certificate is used to sign phase 1 IKE intra-domain exchanges between DFs (which are used in Electronic Surveillance). Although Local System Name is optional, it is REQUIRED when the Local System CA signs this certificate. The IP address MUST be specified in standard dotted-quad notation, e.g., 245.120.75.22.
+
+**Table 38 – DF Certificate**
+
+|                   |                                                                                                                                                                                                                                                                                                           |
+|-------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Subject name form | C=<Country>, O=<Company>, OU=[<Local System Name>], OU=IPCablecom Electronic Surveillance, CN=<IP address>                                                                                                                                                                                                |
+| Intended usage    | To authenticate IKE key management, used to establish IPsec Security Associations between pairs of DFs. These Security Associations are used when a subject that is being legally wiretapped forwards the call and event messages containing call info have to be forwarded to a new wiretap server (DF). |
+| Signed by         | Telephony Service Provider Certificate or Local System Certificate                                                                                                                                                                                                                                        |
+| Validity period   | 20 years                                                                                                                                                                                                                                                                                                  |
+| Modulus length    | 2048                                                                                                                                                                                                                                                                                                      |
+| Extensions        | KeyUsage[n,o](digitalSignature),<br>authorityKeyIdentifier[n,m](keyIdentifier=<subjectKeyIdentifier value from CA certificate>)<br>subjectAltName[n,m](dNSName=<DNSName>)<br>extendedKeyUsage[n,m](iKEIntermediate)                                                                                       |
+
+##### 8.2.3.4.3 IPCablecom Server Certificates
+
+These certificates MUST be verified as part of a certificate chain containing the Service Provider Root Certificate, Service Provider Certificate, Local System Operator Certificate (if used) and the Ancillary Device Certificates.
+
+These certificates are used to identify various servers in the IPCablecom system. For example, they may be used to sign phase 1 IKE exchanges or to authenticate a PKINIT exchange. Although the Local System Name is optional, it is REQUIRED when the Local System CA signs this certificate. IP address values MUST be specified in standard dotted decimal notation: e.g., 245.120.75.22. DNS Name values MUST be specified as a fully qualified domain name (FQDN): e.g., device.packetcable.com.
+
+**Table 39 – IPCablecom Server Certificates**
+
+| <b>IP Cablecom Server Certificates</b> |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+|----------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Subject name form                      | <p>C=&lt;Country&gt;<br/>O=&lt;Company&gt;<br/>OU=PacketCable<br/>OU=[&lt;Local System Name&gt;]<br/>OU=&lt;Sub-System Name&gt; [&amp;&lt;Sub-System Name&gt;]<br/>CN=&lt;Server Identifier&gt;]</p> <p>or</p> <p>CN=[&lt;Element ID&gt;][&amp;&lt;Element ID&gt;]</p> <p>The CN will contain either a &lt;Server Identifier&gt; or one or more &lt;Element ID&gt;s. If the CN contains a &lt;Server Identifier&gt;, the value of &lt;Server Identifier&gt; MUST be the server's FQDN or its IP address, optionally followed by a colon (:) and an Element ID with no white space either before or after the colon.</p> <p>&lt;Element ID&gt; is the identifier that appears in billing event messages; it MUST be included in a certificate of every server that is capable of generating event messages. This includes a CMS, CMTS and MGC. There MAY be multiple &lt;Element ID&gt; fields, each separated by the character "&amp;". ITU-T Rec. J.164 defines the Element ID as a 5-octet right-justified, space-padded ASCII-encoded numerical string. When converting the Element ID for use in a certificate, any spaces MUST be converted to ASCII zeroes (0x30).</p> <p>For example, a CMTS that has the Element ID "311" will have a common name "00311".</p> <p>The value of &lt;Sub-System Name&gt; MUST be one of the following:</p> <ul style="list-style-type: none"><li>– for Border Proxy: bp</li><li>– for Cable Modem Termination System: cmts</li><li>– for Call Management Server: cms</li><li>– for Media Gateway: mg</li><li>– for Media Gateway Controller: mgc</li><li>– for Media Player: mp</li><li>– for Media Player Controller: mpc</li><li>– for Provisioning Server: ps</li><li>– for Record Keeping Server: rks</li><li>– for Signalling Gateway: sg</li></ul> <p>Components that contain combined elements (such as a CMS with an integrated MGC) MUST indicate this in the Subject Name by including all Sub-System Names, joined with the character "&amp;", in the OU field. In the case of combined elements, a single Element ID or multiple Element IDs may be used. If multiple Element IDs are used, all Element IDs MUST be included in the CN, and the order of these Element IDs MUST correspond to the order of the Sub-System Name fields in the OU. The following is an example OU and CN for a combined CMS and MGC. The CMS with Element ID "311" and a MGC with Element ID "312".</p> |
+
+**Table 39 – IPCablecom Server Certificates**
+
+| <b>IP Cablecom Server Certificates</b> |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
+|----------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Subject name form                      | OU=cms&mgc<br>CN=00311&00312<br>The following is an example OU and CN for a combined CMS and MGC. In this case, the CMS and MGC share a single Element ID of "311".<br>OU=cms&mgc<br>CN=00311&00311                                                                                                                                                                                                                                                                                                                                                                                                                              |
+| Intended usage                         | These certificates are used to identify various servers in the IPCablecom system. For example they may be used to sign phase 1 IKE exchanges or to authenticate a device in a PKINIT exchange.                                                                                                                                                                                                                                                                                                                                                                                                                                   |
+| Signed by                              | Telephony Service Provider Certificate or Local System Certificate                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
+| Validity period                        | Set by MSO policy                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
+| Modulus length                         | 2048                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
+| Extensions                             | keyUsage[c,o](digitalSignature, keyEncipherment)<br>authorityKeyIdentifier[n,m](keyIdentifier=<subjectKeyIdentifier value from CA cert>)<br>subjectAltName[n,o](dNSName=<DNSName>   iPAAddress=<IP Address Name>)<br>The keyUsage tag is optional. When it is used it MUST be marked as critical.<br>The subjectAltName extension MUST be included for all servers that are capable of generating event messages.<br>For all other servers, the subjectAltName extension MAY be included. If the subjectAltName extension is included, it MUST include the corresponding name value as specified in the CN field of the subject. |
+
+##### **8.2.3.4.4 TLS Certificates**
+
+These certificates MUST be verified as part of a certificate chain containing the Service Provider Root Certificate, Service Provider Certificate, Local System Operator Certificate (if used) and the Ancillary Device Certificates.
+
+These certificates are used to authenticate TLS handshake exchanges (and encrypt when using RSA key exchange). Although the Local System Name is optional, it is REQUIRED when the Local System CA signs this certificate. DNS Name values MUST be specified as a fully qualified domain name (FQDN): e.g., device.packetcable.com.
+
+**Table 40 – TLS Certificates**
+
+| <b>Server Certificates</b> |                                                                                                                                                                                                                                   |
+|----------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Subject name form          | C=<Country><br>O=<Company><br>OU=[<Local System Name>]<br>OU= IPCablecom<br>CN=[<Server Identifier>]<br>The value of <Server Identifier> MUST be the server's FQDN. Note that only a single FQDN can be included in the CN field. |
+| Intended usage             | These certificates are used to authenticate TLS handshake exchanges (and encrypt when using RSA key exchange).                                                                                                                    |
+| Signed by                  | Telephony Service Provider Certificate or Local System Certificate                                                                                                                                                                |
+| Validity period            | Set by operator policy                                                                                                                                                                                                            |
+| Modulus length             | 1024, 1536, 2048                                                                                                                                                                                                                  |
+| Extensions                 | KeyUsage[c,m](digitalSignature, keyEncipherment)<br>extendedKeyUsage[n,m] (id-kp-serverAuth, id-kp-clientAuth)<br>authorityKeyIdentifier[n,m](keyIdentifier=<subjectKeyIdentifier value from CA cert>)                            |
+
+### 8.2.4 Certificate revocation
+
+For future study.
+
+# 9 Cryptographic algorithms
+
+This clause describes the cryptographic algorithms used in the IPCablecom security Recommendation. When a particular algorithm is used, the algorithm MUST follow the corresponding specification.
+
+## 9.1 AES
+
+AES-128 is a 128-bit block cipher that MUST be implemented according to the Advanced Encryption Standard (AES) proposal specified in AES – The Rijndael Block Cipher. AES-128 is used in CBC mode with a 128-bit block size in IPCablecom. AES-128 requires 10 rounds of cryptographic operations in encryption or decryption. The Initialization Vector for CBC mode is specified for each use of AES in IPCablecom.
+
+In 1997, the National Institute of Standards and Technology (NIST) initiated a process to select a symmetric-key encryption algorithm to be used to protect sensitive (unclassified) Federal information in furtherance of NIST's statutory responsibilities. In 1998, NIST announced the acceptance of fifteen candidate algorithms and requested the assistance of the cryptographic research community in analysing the candidates. This analysis included an initial examination of the security and efficiency characteristics for each algorithm. NIST reviewed the results of this preliminary research and selected MARS, RC6(TM), Rijndael, Serpent and Twofish as finalists. Having reviewed further public analysis of the finalists, NIST has decided to propose Rijndael as the Advanced Encryption Standard.
+
+## 9.2 DES
+
+The Data Encryption Standard (DES) is specified in FIPS PUB 81. For Media Stream encryption, IPCablecom does not require error checking on the DES key, and the full 64 bits of key provided to the DES algorithm will be generated according to 7.6.2.3.3.1.
+
+### 9.2.1 XDESX
+
+An option for the encryption of RTP packets is DESX-XEX. XDESX, or DESX, has been proven as a viable method for overcoming the weaknesses in DES while not greatly adding to the implementation complexity. The strength of DESX against key search attacks is presented in FIPS PUB 81. The CBC mode of DESX-XEX is shown in Figure 24 below, where DESX-XEX is executed within the block called "block cipher". Inside the block, DESX-XEX is performed as shown in Figure 26 below using a 192-bit key. K1 is the first 8 bytes of the key, and K2 represents the second 8 bytes of the key; and K3 the third 8 bytes of the key.
+
+### 9.2.2 DES-CBC-PAD
+
+This variant of DES is also based on the analysis of DESX presented in *How to protect DES Against Exhaustive Key Search*. When using DESX in CBC mode, an optimized architecture is possible. It can be described in terms of the DES-CBC configuration plus the application of a random pad on the final DES-CBC output blocks. This configuration uses 128 bits of keying material, where 64 bits are applied to the DES block according to FIPS PUB 81, and an additional 64 bits of keying material are applied as the random pad on the final DES-CBC output blocks.
+
+In this case, the same IV used to initialize the CBC mode is used as keying material for the random pad. Each block of DES-CBC encrypted output is XORed with the 64-bit Initialization Vector that was used to start the CBC operation. If a short block results from using residual block termination (see 9.3), the left-most-bits of the IV are used in the final XOR padding operation. This mode of DES-CBC is shown in Figure 25 below, where DES is executed in the block called "block cipher". A 64-bit key value is used.
+
+### 9.2.3 3DES-EDE
+
+Another option for the encryption of RTP packets for IPCablecom is 3DES-EDE-CBC. The CBC mode of 3DES-EDE is shown in Figure 24 below, where 3DES-EDE is executed within the block called "block cipher." Inside the block, 3DES-EDE is performed as shown in Figure 27 below using a 128-bit key. K1 is the first 8 bytes of the key, and K2 represents the second 8 bytes of key; and K3 = K1.
+
+## 9.3 Block termination
+
+If block ciphers are supported, a short block ( $n \text{ bits} < \text{block size}$ , depending on the cipher algorithms) MUST be terminated by residual block termination as shown in Figure 28. Residual block termination (RBT) is executed as follows:
+
+Given a final block having  $n$  bits, where  $n$  is less than the block size, the  $n$  bits are padded up to a block by appending  $(\text{block size} - n)$  bits of arbitrary value to the right of the  $n$ -bits. The resulting block is encrypted using  $B$ -bit CFB mode, with the next-to-last ciphertext block serving as the initialization vector for the CFB operation (see B. Schneier's *Applied Cryptography*). Here,  $B$  stands for the cipher-specific block size. The leftmost  $n$  bits of the resulting ciphertext are used as the short cipher block. In the special case where the complete payload is less than the cipher block size, the procedure is the same as for a short final block, with the provided initialization vector serving as the initialization vector for the operation. Residual block termination is illustrated in Figure 28 for both encryption and decryption operations.
+
+### **CBC encryption architecture**
+
+![Diagram of CBC encryption architecture showing three blocks. Each block consists of an XOR gate followed by a 'Block cipher'. The first block takes plaintext P_i and an Initialization Vector (IV) as input to the XOR gate. The output of the XOR gate is passed to the 'Block cipher', which produces ciphertext C_i. The ciphertext C_i is then passed as input to the XOR gate of the second block along with plaintext P_{i+1}. The second block produces ciphertext C_{i+1}, which is passed to the third block along with plaintext P_{i+2}. The third block produces ciphertext C_{i+2}.](e4e0e43b969b09f3ef8ed29722d4d427_img.jpg)
+
+The diagram illustrates the CBC encryption process. It shows three sequential blocks. Each block contains an XOR gate (represented by a circle with a plus sign) and a 'Block cipher' (represented by a rectangle).  
+1. The first block takes plaintext  $P_i$  and an Initialization Vector (IV) as input to the XOR gate. The output of the XOR gate is passed to the 'Block cipher', which produces ciphertext  $C_i$ .  
+2. The ciphertext  $C_i$  is passed as input to the XOR gate of the second block along with plaintext  $P_{i+1}$ . The output of this XOR gate is passed to the 'Block cipher', which produces ciphertext  $C_{i+1}$ .  
+3. The ciphertext  $C_{i+1}$  is passed as input to the XOR gate of the third block along with plaintext  $P_{i+2}$ . The output of this XOR gate is passed to the 'Block cipher', which produces ciphertext  $C_{i+2}$ .
+
+Diagram of CBC encryption architecture showing three blocks. Each block consists of an XOR gate followed by a 'Block cipher'. The first block takes plaintext P\_i and an Initialization Vector (IV) as input to the XOR gate. The output of the XOR gate is passed to the 'Block cipher', which produces ciphertext C\_i. The ciphertext C\_i is then passed as input to the XOR gate of the second block along with plaintext P\_{i+1}. The second block produces ciphertext C\_{i+1}, which is passed to the third block along with plaintext P\_{i+2}. The third block produces ciphertext C\_{i+2}.
+
+### **CBC decryption architecture**
+
+![Diagram of CBC decryption architecture showing three blocks. Each block consists of a 'Block cipher' followed by an XOR gate. The first block takes ciphertext C_i as input to the 'Block cipher', which produces an intermediate value. This intermediate value is then passed to the XOR gate along with the Initialization Vector (IV) to produce plaintext P_i. The ciphertext C_i is also passed as input to the XOR gate of the second block along with ciphertext C_{i+1}. The output of this XOR gate is passed to the 'Block cipher', which produces plaintext P_{i+1}. The ciphertext C_{i+1} is also passed as input to the XOR gate of the third block along with ciphertext C_{i+2}. The output of this XOR gate is passed to the 'Block cipher', which produces plaintext P_{i+2}. A label J.170_F24 is present near the final output.](09797d4289ec96309d21a9a993153dab_img.jpg)
+
+The diagram illustrates the CBC decryption process. It shows three sequential blocks. Each block contains a 'Block cipher' (represented by a rectangle) and an XOR gate (represented by a circle with a plus sign).  
+1. The first block takes ciphertext  $C_i$  as input to the 'Block cipher', which produces an intermediate value. This intermediate value is then passed to the XOR gate along with the Initialization Vector (IV) to produce plaintext  $P_i$ .  
+2. The ciphertext  $C_i$  is also passed as input to the XOR gate of the second block along with ciphertext  $C_{i+1}$ . The output of this XOR gate is passed to the 'Block cipher', which produces plaintext  $P_{i+1}$ .  
+3. The ciphertext  $C_{i+1}$  is also passed as input to the XOR gate of the third block along with ciphertext  $C_{i+2}$ . The output of this XOR gate is passed to the 'Block cipher', which produces plaintext  $P_{i+2}$ . A label  $J.170\_F24$  is present near the final output.
+
+Diagram of CBC decryption architecture showing three blocks. Each block consists of a 'Block cipher' followed by an XOR gate. The first block takes ciphertext C\_i as input to the 'Block cipher', which produces an intermediate value. This intermediate value is then passed to the XOR gate along with the Initialization Vector (IV) to produce plaintext P\_i. The ciphertext C\_i is also passed as input to the XOR gate of the second block along with ciphertext C\_{i+1}. The output of this XOR gate is passed to the 'Block cipher', which produces plaintext P\_{i+1}. The ciphertext C\_{i+1} is also passed as input to the XOR gate of the third block along with ciphertext C\_{i+2}. The output of this XOR gate is passed to the 'Block cipher', which produces plaintext P\_{i+2}. A label J.170\_F24 is present near the final output.
+
+**Figure 24 – CBC Mode**
+
+### **CBC-PAD encryption architecture**
+
+![Diagram of CBC-PAD encryption architecture showing three blocks. For each block i, plaintext P_i is XORed with the IV (or previous ciphertext C_i) and then passed through a 'Block cipher' using a key. The output is ciphertext C_i. The IV for the next block is set to the current ciphertext C_i.](d24991add1927bb17af2ee171454a31f_img.jpg)
+
+The diagram illustrates the CBC-PAD encryption process across three blocks. 
+   
+Block 1: Plaintext  $P_i$  is input to an XOR gate along with the Initialization Vector (IV). The output of the XOR gate is passed to a 'Block cipher' block. The 'Block cipher' also takes a key (labeled 'Key = IV') as input. The output of the 'Block cipher' is ciphertext  $C_i$ .
+   
+Block 2: Plaintext  $P_{i+1}$  is input to an XOR gate along with the previous ciphertext  $C_i$  (which serves as the IV for this block). The output is passed to a 'Block cipher' block with key 'Key = IV', resulting in ciphertext  $C_{i+1}$ .
+   
+Block 3: Plaintext  $P_{i+2}$  is input to an XOR gate along with the previous ciphertext  $C_{i+1}$ . The output is passed to a 'Block cipher' block with key 'Key = IV', resulting in ciphertext  $C_{i+2}$ .
+   
+Arrows indicate the flow of data:  $P_i, P_{i+1}, P_{i+2}$  enter their respective XOR gates; IV enters the first XOR gate;  $C_i, C_{i+1}$  are passed to the next XOR gates; and the final outputs are  $C_i, C_{i+1}, C_{i+2}$ .
+
+Diagram of CBC-PAD encryption architecture showing three blocks. For each block i, plaintext P\_i is XORed with the IV (or previous ciphertext C\_i) and then passed through a 'Block cipher' using a key. The output is ciphertext C\_i. The IV for the next block is set to the current ciphertext C\_i.
+
+### **CBC-PAD decryption architecture**
+
+![Diagram of CBC-PAD decryption architecture showing three blocks. For each block i, ciphertext C_i is XORed with the key (IV) and then passed through a 'Block cipher'. The output is then XORed with the IV (or previous ciphertext C_i) to produce plaintext P_i. The IV for the next block is set to the current ciphertext C_i.](893d65bf826925a7283359b1672010a0_img.jpg)
+
+The diagram illustrates the CBC-PAD decryption process across three blocks. 
+   
+Block 1: Ciphertext  $C_i$  is input to an XOR gate along with a key (labeled 'Key = IV'). The output is passed to a 'Block cipher' block. The output of the 'Block cipher' is then input to another XOR gate along with the IV, resulting in plaintext  $P_i$ .
+   
+Block 2: Ciphertext  $C_{i+1}$  is input to an XOR gate along with the key 'Key = IV'. The output is passed to a 'Block cipher' block. The output is then input to an XOR gate along with the previous ciphertext  $C_i$  (which serves as the IV), resulting in plaintext  $P_{i+1}$ .
+   
+Block 3: Ciphertext  $C_{i+2}$  is input to an XOR gate along with the key 'Key = IV'. The output is passed to a 'Block cipher' block. The output is then input to an XOR gate along with the previous ciphertext  $C_{i+1}$ , resulting in plaintext  $P_{i+2}$ .
+   
+Arrows indicate the flow of data:  $C_i, C_{i+1}, C_{i+2}$  enter their respective first XOR gates; the key 'Key = IV' enters each first XOR gate; the outputs of the 'Block cipher' blocks enter the second XOR gates; IV enters the first second XOR gate;  $C_i, C_{i+1}$  are passed to the subsequent second XOR gates; and the final outputs are  $P_i, P_{i+1}, P_{i+2}$ . A small label 'J.170\_F25' is present at the bottom right.
+
+Diagram of CBC-PAD decryption architecture showing three blocks. For each block i, ciphertext C\_i is XORed with the key (IV) and then passed through a 'Block cipher'. The output is then XORed with the IV (or previous ciphertext C\_i) to produce plaintext P\_i. The IV for the next block is set to the current ciphertext C\_i.
+
+**Figure 25 – CBC Pad Mode**
+
+**Encryption**
+
+![Encryption diagram showing a block cipher structure with XOR and DES Encrypt components.](61474739fd197587cfea52af9b6a3885_img.jpg)
+
+The encryption diagram shows a vertical flow of data. It starts with an input arrow pointing to a box labeled "Block cipher". To the right of this box is a large right-pointing arrow. Further right is a large rectangular box containing a vertical sequence of operations: an XOR gate (circle with a plus sign), a "DES Encrypt" box, and another XOR gate. The input data enters the top XOR gate from above. Key K1 is input to this XOR gate from the left. The output of the first XOR gate enters the "DES Encrypt" box. Key K2 is input to the "DES Encrypt" box from the left. The output of the "DES Encrypt" box enters the second XOR gate. Key K3 is input to this XOR gate from the left. The final output of the second XOR gate exits the bottom of the large rectangular box.
+
+Encryption diagram showing a block cipher structure with XOR and DES Encrypt components.
+
+**Decryption**
+
+![Decryption diagram showing a block cipher structure with XOR and DES Decrypt components.](137bcfed81ada68ca5162ca5afed35c7_img.jpg)
+
+The decryption diagram shows a vertical flow of data. It starts with an input arrow pointing to a box labeled "Block cipher". To the right of this box is a large right-pointing arrow. Further right is a large rectangular box containing a vertical sequence of operations: an XOR gate (circle with a plus sign), a "DES Decrypt" box, and another XOR gate. The input data enters the top XOR gate from above. Key K3 is input to this XOR gate from the left. The output of the first XOR gate enters the "DES Decrypt" box. Key K2 is input to the "DES Decrypt" box from the left. The output of the "DES Decrypt" box enters the second XOR gate. Key K1 is input to this XOR gate from the left. The final output of the second XOR gate exits the bottom of the large rectangular box. To the right of the bottom of the large rectangular box is the text "J.170\_F26".
+
+Decryption diagram showing a block cipher structure with XOR and DES Decrypt components.
+
+**Figure 26 – DESX-XEX as Block Cipher**
+
+![Diagram of 3DES-EDE encryption process Diagram of 3DES-EDE decryption process](af4f213abb5ad1891a43425e0d758021_img.jpg)
+
+**Encryption**
+
+The encryption diagram shows a vertical sequence of three DES blocks: 'DES Encrypt', 'DES Decrypt', and 'DES Encrypt'. The first 'DES Encrypt' block receives an input from above and key K1 from the left. Its output goes to the 'DES Decrypt' block, which receives key K2 from the left. The output of 'DES Decrypt' goes to the final 'DES Encrypt' block, which receives key K3 from the left. The output of this final block is enclosed in a box and points down. To the left of this box is a 'Block cipher' box with a large hollow arrow pointing from the 3DES sequence to it. The 'Block cipher' box has an input from above and an output pointing down.
+
+**Decryption**
+
+The decryption diagram shows a vertical sequence of three DES blocks: 'DES Decrypt', 'DES Encrypt', and 'DES Decrypt'. The first 'DES Decrypt' block receives an input from above and key K3 from the left. Its output goes to the 'DES Encrypt' block, which receives key K2 from the left. The output of 'DES Encrypt' goes to the final 'DES Decrypt' block, which receives key K1 from the left. The output of this final block is enclosed in a box and points down. To the left of this box is a 'Block cipher' box with a large hollow arrow pointing from the 3DES sequence to it. The 'Block cipher' box has an input from above and an output pointing down. The label 'J.170\_F27' is located at the bottom right of the diagram.
+
+Diagram of 3DES-EDE encryption process Diagram of 3DES-EDE decryption process
+
+**Figure 27 – 3DES-EDE as Block Cipher**
+
+![Diagram of CBC encryption with residual block termination. It shows three 'Block cipher' units. The first takes IV and P_i as input to an XOR gate, then the output goes to a 'Block cipher' to produce C_i. The second takes C_i and P_{i+1} as input to an XOR gate, then the output goes to a 'Block cipher' to produce C_{i+1}. The third takes C_{i+1} and a 'Select leftmost j-bits' of C_{i+1} as input to an XOR gate, then the output goes to a 'Block cipher' to produce C_{i+2}. Finally, P_{i+2} and the 'Select leftmost j-bits' of C_{i+2} are XORed to produce the final output. Diagram of CBC decryption with residual block termination. It shows three 'Block cipher' units. The first takes C_i and IV as input to an XOR gate, then the output goes to a 'Block cipher' to produce P_i. The second takes P_i and C_{i+1} as input to an XOR gate, then the output goes to a 'Block cipher' to produce P_{i+1}. The third takes P_{i+1} and a 'Select leftmost j-bits' of P_{i+1} as input to an XOR gate, then the output goes to a 'Block cipher' to produce P_{i+2}. Finally, C_{i+2} and the 'Select leftmost j-bits' of P_{i+2} are XORed to produce the final output, labeled J.170_F28.](43f7b6b61db9a2f3e3920740a9527d97_img.jpg)
+
+**Encryption**  
+**CBC w/ residual block termination**
+
+**Decryption**  
+**CBC w/ residual block termination**
+
+Diagram of CBC encryption with residual block termination. It shows three 'Block cipher' units. The first takes IV and P\_i as input to an XOR gate, then the output goes to a 'Block cipher' to produce C\_i. The second takes C\_i and P\_{i+1} as input to an XOR gate, then the output goes to a 'Block cipher' to produce C\_{i+1}. The third takes C\_{i+1} and a 'Select leftmost j-bits' of C\_{i+1} as input to an XOR gate, then the output goes to a 'Block cipher' to produce C\_{i+2}. Finally, P\_{i+2} and the 'Select leftmost j-bits' of C\_{i+2} are XORed to produce the final output. Diagram of CBC decryption with residual block termination. It shows three 'Block cipher' units. The first takes C\_i and IV as input to an XOR gate, then the output goes to a 'Block cipher' to produce P\_i. The second takes P\_i and C\_{i+1} as input to an XOR gate, then the output goes to a 'Block cipher' to produce P\_{i+1}. The third takes P\_{i+1} and a 'Select leftmost j-bits' of P\_{i+1} as input to an XOR gate, then the output goes to a 'Block cipher' to produce P\_{i+2}. Finally, C\_{i+2} and the 'Select leftmost j-bits' of P\_{i+2} are XORed to produce the final output, labeled J.170\_F28.
+
+**Figure 28 – CBC with Residual Block Termination**
+
+## 9.4 RSA signature
+
+All public key signatures for IPCablecom MUST be generated and verified using the RSA signature algorithm described in RFC 2437. The format for all IPCablecom RSA signatures MUST be compliant with the Cryptographic Message Syntax of RFC 2630.
+
+## 9.5 HMAC-SHA-1
+
+The keyed hash employed by the HMAC-Digest Attribute MUST use the HMAC message authentication method per RFC 2104 with the SHA-1 hash algorithm per FIPS PUB 180-1.
+
+## 9.6 Key derivation
+
+Key derivation clauses in this Recommendation refer to a function  $F(S, \text{seed})$ , where  $S$  is a shared secret from which keying material is derived, and  $\text{seed}$  is a constant string of bytes. Below is the specification of  $F(S, \text{seed})$ , borrowed from TLS (RFC 2246):
+
+$$F(S, \text{seed}) = \text{HMAC\_SHA-1}(S, A(1) + \text{seed}) + \text{HMAC\_SHA-1}(S, A(2) + \text{seed}) + \text{HMAC\_SHA-1}(S, A(3) + \text{seed}) + \dots$$
+
+where  $+$  indicates concatenation.
+
+$A(0)$  is defined as:  $A(0) = \text{seed}$   
+ $A(i) = \text{HMAC\_SHA-1}(S, A(i - 1))$
+
+$F(S, \text{seed})$  is iterated as many times as is necessary to produce required quantity of data. Unused bytes at the end of the last iteration will be discarded.
+
+## 9.7 The MMH-MAC
+
+In this clause the MMH Function and the MMH Message Authentication Code (MAC) are described. The MMH-MAC is the message authentication code option for the media flows. As discussed in 7.6.2, the MMH-MAC is computed over the RTP header and the payload is generated by the codec. The MMH Function will be described next, followed by a description of the MMH-MAC.
+
+### 9.7.1 The MMH Function
+
+The Multilinear Modular Hash (MMH) Function described below is a variant of the MMH Function described in *MMH: Software Message Authentication in Gbit/second Rates*. Some of the computations described below use signed arithmetic whereas the computations in *MMH: Software Message Authentication in Gbit/second Rates* use unsigned arithmetic. The signed arithmetic variant described here was selected for its computational efficiency when implemented on DSPs. All of the properties shown for the MMH function in *MMH: Software Message Authentication in Gbit/second Rates* continue to hold for the signed variant.
+
+The MMH Function has three parameters: the word size, the number of words of input, and the number of words of output.  $\text{MMH}[\omega, s, t]$  specifies the hash function with word size  $\omega$ ,  $s$  input words, and  $t$  output words. For IPCablecom the word size is fixed to 16 bits:  $\omega = 16$ . The number of output words will be either 1 or 2:  $t \in \{1, 2\}$ . The MMH Hash Function will first be described for  $t = 1$ , i.e., one output word.
+
+#### 9.7.1.1 MMH[16, s, 1]
+
+For the remainder of this clause,  $\text{MMH}[16, s, 1]$  is denoted by  $H$ . In addition to  $s$  words of input,  $H$  also takes as input a key of  $s$  words. When  $H$  is used in computing the MMH-MAC, the key is randomly generated and remains fixed for several inputs as described in 9.7.2. The key is denoted by  $k$  and the  $i$ th word of the key by  $k_i$ :  $k = k_1, k_2, \dots, k_s$ . Likewise the input message is denoted by  $m$  and the  $i$ th word of the input message by  $m_i$ :  $m = m_1, m_2, \dots, m_s$ .
+
+To describe  $H$ , the following definitions are needed. For any even positive integer  $n$ ,  $S_n$  is defined to be the following set of  $n$  integers:  $\{-n/2, \dots, 0, \dots, (n/2) - 1\}$ . For example,  $S_{2^{16}} = \{-2^{15}, \dots, 0, \dots, 2^{15} - 1\}$  is the set of signed 16-bit integers. For any integer  $z$ ,  $z \bmod n$  is the unique element  $\omega$  of  $S_n$  such that  $z \equiv \omega \pmod{n}$ . For example, if  $z$  is a 32-bit signed integer in 32-bit twos complement representation, then  $z \bmod 2^{16}$  can be computed by taking the 16 least significant bits of  $z$  and interpreting those bits in 16-bit twos complement representation.
+
+For any positive integer  $q$ ,  $Z_q$  denotes the following set of  $q$  integers:  $\{0, 1, \dots, q - 1\}$ .
+
+As described above,  $H$  takes as input a key of  $s$  words. Each of the  $s$  words is interpreted as a 16-bit signed integer, i.e., an element of  $S_{2^{16}}$ .  $H$  also takes as input a message of  $s$  words. Each of the  $s$  words is interpreted as a 16-bit signed integer, i.e., an element of  $S_{2^{16}}$ . The output of  $H$  is an unsigned 16-bit integer, i.e., an element of  $Z_{2^{16}}$ . Alternatively, the range of  $H$  is  $S_{2^{16}}^S \times S_{2^{16}}^S$  and the domain is  $Z_{2^{16}}$ .
+
+$H$  is defined by a series of steps. For  $k, m \in S_{2^{16}}^S$ :
+
+- 1) define  $H_1$  as  $H_1(k, m) = \sum_{i=1}^S k_i \cdot m_i \bmod 2^{32}$ ;
+- 2) define  $H_2$  as  $H_2(k, m) = H_1(k, m) \bmod p$  where  $p$  is the prime number  $p = 2^{16} + 1$ ;
+
+3) define  $H$  as  $H(k,m) = H_2(k,m) \bmod 2^{16}$ .
+
+Equivalently:
+
+$$H(k,m) = \left( \left( \left( \sum_{i=1}^s k_i \cdot m_i \right) \bmod 2^{32} \right) \bmod p \right) \bmod 2^{16}$$
+
+Each step is discussed in detail below.
+
+**Step 1)**  $H_1(k,m)$  is the inner product of two vectors each of  $s$  16-bit signed integers. The result of the inner product is taken  $\bmod 2^{32}$  to yield an element of  $S_{2^{32}}$ <sup>6</sup>. That is, if the inner product is in twos complement representation of 32 or more bits, the 32 least significant bits are retained and the resulting integer is interpreted in 32-bit twos complement representation.
+
+**Step 2)** This step consists of taking an element  $x$  of  $S_{2^{32}}$  and reducing it  $\bmod p$  to yield an element of  $Z_p$ . If  $x$  is represented in 32-bit twos complement notation, then this reduction can be accomplished very simply as follows. Let  $a$  be the unsigned integer given by the 16 most significant bits of  $x$ . Let  $b$  be the unsigned integer given by the 16 least significant bits of  $x$ . There are two cases depending upon whether  $x$  is negative.
+
+Case i) If  $x$  is non-negative then  $x = a2^{16} + b$  where  $a \in \{0, \dots, 2^{15} - 1\}$  and  $b \in \{0, \dots, 2^{16} - 1\}$ .
+
+From the modular equation:
+
+$$a2^{16} + b \equiv a2^{16} + b - a(2^{16} + 1) \pmod{2^{16} + 1}$$
+
+it follows that  $x \equiv b - a \pmod{p}$ . The quantity  $b - a$  is in the range  $\{-2^{15} + 1, \dots, 2^{16} - 1\}$ . Therefore if  $b - a$  is non-negative then  $x \bmod p = b - a$ . If  $b - a$  is negative then  $x \bmod p = b - a + p$ .
+
+Case ii) If  $x$  is negative then  $x = a2^{16} + b - 2^{32}$  where  $a \in \{2^{15}, \dots, 2^{16} - 1\}$  and  $b \in \{0, \dots, 2^{16} - 1\}$ . From the modular equation:
+
+$$a2^{16} + b - 2^{32} \equiv b + a2^{16} - a(2^{16} + 1) - 2^{32} + 2^{16}(2^{16} + 1) \pmod{2^{16} + 1}$$
+
+it follows that  $x \equiv (b - a + 2^{16}) \pmod{p}$ . The quantity  $b - a + 2^{16}$  is in the range  $\{2^{15} + 1, \dots, 2^{17} - 1\}$ . Therefore, if  $b - a < p$  then  $x \bmod p = b - a$ . If  $b - a \geq p$  then  $x \bmod p = b - a - p$ .
+
+**Step 3)** This step takes an element of  $Z_p$  and reduces it  $\bmod 2^{16}$ . This is equivalent to taking the 16 least significant bits.
+
+#### 9.7.1.2 MMH[16,s,2]
+
+This clause describes the MMH Function with an output length of two words, which in this case is 32 bits. For convenience, let  $H' = \text{MMH}[16,s,2]$ .  $H'$  takes a key of  $s + 1$  words. Let  $k = k_1, \dots, k_{s+1}$ . Furthermore, define  $k^{(1)}$  to be the  $s$  words of  $k$  starting with  $k_1$ , i.e.,  $k^{(1)} = k_1, \dots, k_s$ . Define  $k^{(2)}$  to be the  $s$  words of  $k$ , starting with  $k_2$ , i.e.,  $k^{(2)} = k_2, \dots, k_{s+1}$ . For any  $k \in S_{2^{16}}^{s+1}$  and any  $m \in S_{2^{16}}^s$ ,  $H'(k,m)$  is computed by first computing  $H(k^{(1)},m)$  and then  $H(k^{(2)},m)$  and concatenating the results. That is,  $H'(k,m) = H(k^{(1)},m) \circ H(k^{(2)},m)$ .
+
+<sup>6</sup> The entire sum need not be computed before performing the  $\bmod 2^{32}$  operation. The  $\bmod 2^{32}$  operation can be computed on partial sums since  $(x + y) \bmod 2^{32} = (x \bmod 2^{32} + y \bmod 2^{32}) \bmod 2^{32}$ .
+
+### 9.7.2 The MMH-MAC
+
+This clause describes the MMH-MAC. The MMH-MAC has three parameters: the word size, the number of words of input, and the number of words of output. MMH-MAC[ $\omega, s, t$ ] specifies the message authentication code with word size  $\omega$ ,  $s$  input words and  $t$  output words. For IPCablecom the word size is fixed to 16 bits:  $\omega = 16$ . The number of output words will be either 1 or 2:  $t \in \{1, 2\}$ .
+
+For convenience, let  $M = \text{MMH-MAC}[16, s, t]$ . When using  $M$ , a sender and receiver share a key  $k$  of  $s + t - 1$  words. In addition, they share a sequence of key streams of  $t$  words each, one one-time pad for each message sent. Let  $r^{(i)}$  be the key stream used for the  $i$ th message sent and received. For the  $i$ th message,  $m^{(i)}$ , the message authentication code is computed as:
+
+$$M(k, r^{(i)}, m^{(i)}) = H(k, m^{(i)}) + r^{(i)}$$
+
+Here  $H = \text{MMH}[16, s, t]$ ,  $r^{(i)}$  is in  $Z_{2^{16}}$  and addition is mod  $2^{16}$ .
+
+#### 9.7.2.1 MMH-MAC when using a block cipher
+
+When calculating the MMH-MAC when encryption is performed by one of the available block ciphers, the block cipher is used to calculate the  $t$  words of  $r^{(i)}$  key stream (pad) as defined in 7.6.2.1.2.2.3.
+
+#### 9.7.2.2 Handling variable-size data
+
+In order to handle data of all possible sizes up to a maximum value, the following rules MUST be followed for computing an MMH function:
+
+- If the data is not a multiple of the word size, pad the data up to a multiple of the word size (16 bits) with zero-bytes. In other words, if the length of message  $m$  is not a multiple of word size  $w$ , but rather of length  $b$  octets,  $b = n \times w + r$  with  $n \geq 0$  and  $0 < r < w$ , then pad message  $m$  at the end with  $w - r$  zero-bytes before passing it as the input to  $M$ .
+- If the key is larger than what is needed for a particular message, truncate the key. In other words, if a message  $m$  is not of length  $s$  words, but rather of length  $v < s$  words, then truncate the value of the key  $k$  to  $v + t - 1$  words before it is used to calculate the MMH hash. (For MMH hash with 1 word output,  $t = 1$  and  $k$  is truncated to  $v$  words. For 2-word output,  $t = 2$  and  $k$  is truncated to  $v + 1$  words.)
+
+## 9.8 Random number generation
+
+Good random number generation is vital to most cryptographic mechanisms. Implementations SHOULD do their best to produce true-random seeds; they should also use cryptographically strong pseudo-random number generation algorithms. RFC 1750 gives some suggestions; other possibilities include use of a per-MTA secret installed at manufacture time and used in the random number generation process.
+
+# 10 Physical security
+
+## 10.1 Protection for MTA key storage
+
+An MTA MUST maintain in permanent write-once memory an RSA key pair. An MTA SHOULD deter unauthorized physical access to this keying material.
+
+The level of physical protection of keying material required by this Recommendation for an MTA is specified in terms of the security levels defined in FIPS PUBS 140-2, *Security Requirements for Cryptographic Modules*. An MTA SHOULD, at a minimum, meet FIPS PUBS 140-2 Security Level 1 requirements.
+
+This Recommendation's minimal physical security requirements for an MTA will not, in normal practice, jeopardize a customer's data privacy. Assuming the subscriber controls the access to the MTA with the same diligence they would protect a cellular phone, physical attacks on that MTA to extract keying data are likely to be detected by the subscriber.
+
+An MTA's weak physical security requirements, however, could undermine the cryptographic protocol's ability to meet its main security objective: to provide a service operator with strong protection from theft of high value network.
+
+This Recommendation specifies requirements to protect against unauthorized access to these network services by enforcing an end-to-end message integrity and encryption of signalling flows across the network and by employing an authenticated key management protocol. If an attacker is able to legitimately subscribe to a set of services and also gain physical access to an MTA containing keying material, then in the absence of strong physical protection of this information, the attacker can extract keying material from the MTA, and redistribute the keys to other users running modified illegitimate MTAs, effectively allowing theft of network services.
+
+There are two distinct variations of "active attacks" involving the extraction and redistribution of cryptographic keys. These include the following:
+
+- 1) An "RSA active clone" would actively participate in IPCablecom key exchanges. An attacker must have some means by which to remove the cryptographic keys that enable services from the clone master, and install these keys into a clone MTA. An active clone would work in conjunction with an active clone master to passively obtain the clone master's keying material and then actively impersonate the clone master. A single active clone may have numerous active clone master identities from which to select to obtain access to network services. This attack allows, for example, the theft of non-local voice communications.
+- 2) An DH active clone would also actively participate in the IPCablecom key exchanges and like the RSA active clone, would require an attacker to extract the cryptographic keys that enable the service from the clone master and install these keys into a clone MTA. However, unlike the RSA active clone, the DH active clone must obtain the clone master's random number through alternate means or perform the key exchange and risk detection. Like an RSA active clone, an DH active clone may have numerous clone master identities from which to select to obtain access to the network services.
+- 3) An "active black box" MTA, holding another MTA's session or IPsec keys, would use the keys to obtain access to network-based services or traffic flows similar to the RSA active clone. Since both session keys and IPsec keys change frequently, such clones have to be periodically updated with the new keying material, using some out-of-band means.
+
+An active RSA clone, for example, could operate on a cable access network within whatever geographic region the cloned parent MTA was authorized to operate in. Depending upon the degree to which a service operator's subscriber authorization system restricted the location from which the MTA could operate, the clone's scope of operation could extend well beyond a single J.112 MAC domain.
+
+An active clone attack may be detectable by implementing the appropriate network controls in the system infrastructure. Depending on the access fraud detection methods that are in place, a service operator has a good probability of detecting a clone's operation should it attempt to operate within the network. The service operator could then take defensive measures against the detected clone. For example, in the case of an active RSA clone, it could block the device's future network access by including the device certificate on the certificate hot list. Also, the service operator's subscriber authorization system could limit the geographic region over which a subscriber, identified by its cryptographic credentials, could operate. Additionally, the edge router functionality in the CMTS
+
+could limit any access based upon the IP address. These methods would limit the region over which an active RSA clone could operate and reduce the financial incentive for such an attack.
+
+The architectural guidelines for IPCablecom security are determined by balancing the revenues that could be lost due to the classes of active attacks against the cost of the methods to prevent the attack. At the extreme side of preventive methods available to thwart attacks, both physical security equivalent to FIPS PUB 140-1 Security Level 3 and network-based fraud detection methods could be used to limit the access fraud that allows theft of network-based services. The network-based intrusion detection of active attacks allows operators to consider operational defenses as an alternative to increased physical security. If the revenues threatened by the active attacks increase significantly to the point where additional protective mechanisms are necessary, the long-term costs of operational defenses would need to be compared with the costs of migrating to MTAs with stronger physical security. The inclusion of physical security should be an implementation- and product-differentiation-specific decision.
+
+Although the scope of the current IPCablecom Recommendations do not specifically define requirements for MTAs to support any requirements other than voice communications, the goal of the IPCablecom effort is to provide for the eventual inclusion of integrated services. Part of these integrated services may include the "multicast" of high-value content or extremely secure multicast corporate videoconference sessions.
+
+Two additional attacks enabling a compromise of these types of services are defined:
+
+- 1) An "RSA passive clone" passively monitors the parent MTA's key exchanges and, having a copy of the parent MTA's RSA private key, is able to obtain the same traffic keying material the parent MTA has access to. The clone then uses the keying material to decrypt downstream traffic flows it receives across the shared medium. This attack is limited in that it only allows snooping, but if the traffic were of high value, the attack could facilitate the theft of high-value multicast traffic.
+- 2) A "Passive black box" MTA, holding another MTA's short-term (relative to the RSA key) keys, uses the keying material to gain access to encrypted traffic flows similar to the RSA passive clone.
+
+The passive attacks, unlike the active attacks, are not detectable using network-based intrusion detection techniques since these units never make themselves known to the network while performing the attack. However, this type of service theft has unlimited scale since the passive clones and black boxes, even though they operate on different cable access networks (sometimes referred to as the same J.112 MAC domain) as the parent MTA from whom the keys were extracted, gain access to the protected data the parent MTA is currently receiving since the encryption of the data most likely occurred at the source. (These are general IP multicast services, not to be confused with the specific J.112/BPI+ multicast implementation, where passive clones would be restricted to a single downstream CMTS segment.) The snooping of the point-to-point data is limited to the J.112 MAC domain of the parent MTA. Passive attacks may be prevented by ensuring that the cryptographic keys that are used to enable the services cannot be tampered with in any manner.
+
+In setting goals and guidelines for the IPCablecom security architecture, an assessment has to be made of the value of the services and content that can be stolen or monitored by key extraction and redistribution to passive MTAs. The cost of the solution should not be greater than the lost revenue due to theft of the service or subscribers terminating the service due to lack of privacy. However at this time, there is no clear cost that can be attributed to either the lost revenue from high-value multicast services or the loss of subscribers due to privacy issues unique to this type of network. Therefore, it was concluded that passive key extraction and redistribution attacks would pose an indeterminate financial risk to service operators, and that the cost of protection (i.e., incorporation of stronger physical security into the MTA) should be balanced against the value of the risk. As with the active attacks, the decision to include additional functionality to implement physical
+
+security in the MTA should be left as an implementation and product differentiation issue and not be mandated as a requirement of this Recommendation.
+
+## **10.2 MTA key encapsulation**
+
+As stated in the previous clause, FIPS PUB 140-2 Security Level 1 specifies very little actual physical security and that an MTA **MUST** deter unauthorized "physical" access to its keying material. This restricted access also includes any ability to directly read the keying material using any of the MTA interfaces.
+
+One of the (many) requirements of FIPS PUB 140-2 Security Level 3 is that "the entry or output of plaintext Critical Security Parameters (CSPs) be performed using ports that are physically separated from other ports or interfaces that are logically separated using a trusted path from other interfaces. Plaintext CSPs may be entered into or output from the cryptographic module in encrypted form (in which case they may travel through enclosing or intervening systems)". As also mentioned in the previous clause, this Recommendation is not requiring compliance with any of the FIPS PUB 140-2 Security Level 3 requirements.
+
+However, it is strongly recommended that any persistent keying material **SHOULD** be encapsulated such that there is no way to extract the keying material from the MTA using any of the MTA interfaces (either required in the IPCablecom specifications or proprietary provided by the vendor) without modifications to the MTA.
+
+In particular, an MTA subscriber may also be connected to the Internet via a cable modem (which may be embedded in the same MTA). In that case, hackers may potentially exploit any weakness in the configuration of the subscriber's local network and steal MTA's secret and private keys over the network. If instead, the MTA subscriber is connected to a company Intranet, the same threat still exists, although from a smaller group of people.
+
+# **11 Secure software upgrade**
+
+IPCablecom includes only Embedded MTAs. E-MTAs are embedded with J.112/J.122 cable modems (including J.125 BPI+). Embedded MTAs **MUST** have their software upgraded by the cable modem according to the J.112/J.122 and J.125 requirements.
+
+# Annex A
+
+## Oakley groups
+
+PKINIT states that DH parameters SHOULD be taken from the first or second Oakley groups as defined in RFC 2409. Additionally, this Recommendation requires that DH groups are used exactly as defined in RFC 2409.
+
+RFC 2409 defines several so-called "Oakley groups." Only the first two are relevant to this Recommendation. RFC 2409 requires implementations to support the first group, and recommends that they support the second. This annex is included because RFC 2409 does not give values of  $q$  (the  $p-1$  factor) for the groups, and these are necessary in order to encode the dhpublicnumber type used in the subjectPublicKeyInfo data structure in PKINIT.
+
+The first two Oakley groups are defined as follows:
+
+First Oakley Group:
+
+Prime (p):
+
+FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1  
+29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD  
+EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245  
+E485B576 625E7EC6 F44C42E9 A63A3620 FFFFFFFF FFFFFFFF
+
+Generator (g or b):
+
+2.
+
+Factor (q):
+
+7FFFFFFF FFFFFFFF E487ED51 10B4611A 62633145 C06E0E68  
+94812704 4533E63A 0105DF53 1D89CD91 28A5043C C71A026E  
+F7CA8CD9 E69D218D 98158536 F92F8A1B A7F09AB6 B6A8E122  
+F242DABB 312F3F63 7A262174 D31D1B10 7FFFFFFF FFFFFFFF
+
+Second Oakley Group:
+
+Prime (p):
+
+FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1  
+29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD  
+EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245  
+E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED  
+EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE65381  
+FFFFFFFF FFFFFFFF
+
+Generator (g or b):
+
+2.
+
+Factor (q):
+
+7FFFFFFF FFFFFFFF E487ED51 10B4611A 62633145 C06E0E68  
+94812704 4533E63A 0105DF53 1D89CD91 28A5043C C71A026E  
+F7CA8CD9 E69D218D 98158536 F92F8A1B A7F09AB6 B6A8E122  
+F242DABB 312F3F63 7A262174 D31BF6B5 85FFAE5B 7A035BF6  
+F71C35FD AD44CFD2 D74F9208 BE258FF3 24943328 F67329C0  
+FFFFFFFF FFFFFFFF
+
+# **Annex B**
+
+## **Kerberos Network Authentication Service**
+
+See IETF RFC 4120 (2005).
+
+# **Annex C**
+
+## **PKINIT specification**
+
+See IETF RFC 4556 (2006).
+
+# Appendix I
+
+## IPCablecom administration guidelines and best practices
+
+This appendix describes various administration guidelines and best practices recommended by IPCablecom. These are included to help facilitate network administration and/or strengthen overall security in the IPCablecom network.
+
+## I.1 Routine CMS service key refresh
+
+IPCablecom recommends that the CMS service keys be routinely changed (refreshed) at least once every 90 days in order to reduce the risk of key compromises. The refresh period should be a provisioned parameter that can be used in one of the following ways:
+
+- In the case of manual key changes, an administrator is prompted or reminded to manually change a CMS service key.
+- In the case of autonomous key changes (using Kerberos Set/Change Password), it will define the refresh period.
+
+Note that in the case of autonomous key refreshes, whereby administrative overhead and scalability are not an issue, it may be desirable to use a refresh period that is less than 90 days (but at least the maximum ticket lifetime). This may further reduce the risk of key compromise.
+
+# Appendix II
+
+## Example of MMH algorithm implementation
+
+This appendix gives an example implementation of the MMH MAC algorithm. There may be other implementations that have advantages over this example in particular operating environments. This example is for informational purposes only and is meant to clarify the Recommendation.
+
+The example implementation uses the term "MMH16" for the case where the MAC length is 2 octets and "MMH32" for the case where the length is 4 octets.
+
+A main program is included for exercising the example implementation. The output produced by the program is included.
+
+```
+/*
+  Demo of IPCablecom MMH16 and MMH32 MAC algorithms.
+
+  This program has been tested using Microsoft C/C++ Version 5.0.
+  It is believed to port easily to other compilers, but this has
+  not been tested. When porting, be sure to pick the definitions
+  for int16, int32, uint16, and uint32 carefully.
+*/
+#include <stdio.h>
+/*
+  Define signed and unsigned integers having 16 and 32 bits.
+  This is machine/compiler dependent, so pick carefully.
+*/
+typedef short int16;
+typedef unsigned short uint16;
+typedef int int32;
+typedef unsigned int uint32;
+/*
+  Define this symbol to see intermediate values.
+  Comment it out for clean display.
+*/
+#define VERBOSE
+int32 reduceModF4(int32 x) {
+  /*
+    Routine to reduce an int32 value modulo F4, where F4 = 0x10001.
+    Result is in range [0, 0x10000].
+  */
+  int32 xHi, xLo;
+  /* Range of x is [0x80000000, 0x7fffffff]. */
+  /*
+    If x is negative, add a multiple of F4 to make it non-negative.
+    This loop executes no more than two times.
+  */
+  while (x < 0) x += 0x7fff7fff;
+  /* Range of x is [0, 0x7fffffff]. */
+  /* Subtract high 16 bits of x from low 16 bits. */
+  xHi = x >> 16;
+  xLo = x & 0xffff;
+  x = xLo - xHi;
+  /* Range of x is [0xffff8001, 0x0000ffff]. */
+  /* If x is negative, add F4. */
+  if (x < 0) x += 0x10001;
+  /* Range of x is [0, 0x10000]. */
+  return x;
+}
+
+uint16 mmh16(
+  unsigned char *message,
+  unsigned char *key,
+```
+
+```
+
+unsigned char *pad,
+int msgLen) {
+/*
+Compute and return the MMH16 MAC of the message using the indicated key and
+pad.
+The length of the message is msgLen bytes; msgLen must be even.
+The length of the key must be at least msgLen bytes.
+The length of the pad is two bytes. The pad must be freshly picked from a
+secure random source.
+*/
+int16 x, y;
+uint16 u, v;
+int32 sum;
+int i;
+sum = 0;
+for (i=0; i<msgLen; i+=2) {
+    /* Build a 16-bit factor from the next two message bytes. */
+    x = *message++;
+    x <<= 8;
+    x |= *message++;
+    /* Build a 16-bit factor from the next two key bytes. */
+    y = *key++;
+    y <<= 8;
+    y |= *key++;
+    /* Accumulate product of the factors into 32-bit sum */
+    sum += (int32)x * (int32)y;
+    #ifdef VERBOSE
+        printf(" x %04x y %04x sum %08x\n", x & 0xffff, y & 0xffff, sum);
+    #endif
+}
+/* Reduce sum modulo F4 and truncate to 16 bits. */
+u = (uint16) reduceModF4(sum);
+#ifdef VERBOSE
+    printf(" sum mod F4, truncated to 16 bits: %04x\n", u & 0xffff);
+#endif
+/* Build the pad variable from the two pad bytes */
+v = *pad++;
+v <<= 8;
+v |= *pad;
+#ifdef VERBOSE
+    printf(" pad variable: %04x\n", v & 0xffff);
+#endif
+/* Accumulate pad variable, truncate to 16 bits */
+u = (uint16) (u + v);
+#ifdef VERBOSE
+    printf(" mmh16 value: %04x\n", u & 0xffff);
+#endif
+return u;
+}
+
+uint32 mmh32(
+unsigned char *message,
+unsigned char *key,
+unsigned char *pad,
+int msgLen) {
+/*
+Compute and return the MMH32 MAC of the message using the indicated key and
+pad.
+
+The length of the message is msgLen bytes; msgLen must be even.
+The length of the key must be at least (msgLen + 2) bytes.
+The length of the pad is four bytes. The pad must be freshly picked from a
+secure random source.
+*/
+uint16 x, y;
+uint32 sum;
+
+```
+
+```
+
+    x = mmh16(message, key, pad, msgLen);
+    y = mmh16(message, key+2, pad+2, msgLen);
+    sum = x;
+    sum <<= 16;
+    sum |= y;
+    return sum;
+}
+
+void show(char *name, unsigned char *src, int nbytes)
+{
+    /*
+    Routine to display a byte array, in normal or reverse order
+    */
+    int i;
+    enum { BYTES_PER_LINE = 16 };
+    if (name) printf("%s", name);
+    for (i=0; i<nbytes; i++) {
+        if ((i % BYTES_PER_LINE) == 0) printf("\n");
+        printf("%02x ", src[i]);
+    }
+    printf("\n");
+}
+
+int main()
+{
+    uint16 mac16;
+    uint32 mac32;
+    unsigned char message[] = {
+        0x4e, 0x6f, 0x77, 0x20, 0x69, 0x73, 0x20, 0x74, 0x68,
+        0x65, 0x20, 0x74, 0x69, 0x6d, 0x65, 0x2e,
+    };
+    unsigned char key[] = {
+        0x35, 0x2c, 0xcf, 0x84, 0x95, 0xef, 0xd7, 0xdf, 0xb8,
+        0xf5, 0x74, 0x05, 0x95, 0xeb, 0x98, 0xd6, 0xeb, 0x98,
+    };
+    unsigned char pad16[] = {
+        0xae, 0x07,
+    };
+    unsigned char pad32[] = {
+        0xbd, 0xe1, 0x89, 0x7b,
+    };
+    unsigned char macBuf[4];
+    printf("Example of MMH16 computation\n");
+    show("message", message, sizeof(message));
+    show("key", key, sizeof(message));
+    show("pad", pad16, 2);
+    mac16 = mmh16(message, key, pad16, sizeof(message));
+    macBuf[1] = (unsigned char)mac16; mac16 >>= 8;
+    macBuf[0] = (unsigned char)mac16;
+    show("MMH16 MAC", macBuf, 2);
+    printf("\n");
+    printf("Example of MMH32 computation\n");
+    show("message", message, sizeof(message));
+    show("key", key, sizeof(message)+2);
+    show("pad", pad32, 4);
+    mac32 = mmh32(message, key, pad32, sizeof(message));
+    macBuf[3] = (unsigned char)mac32; mac32 >>= 8;
+    macBuf[2] = (unsigned char)mac32; mac32 >>= 8;
+    macBuf[1] = (unsigned char)mac32; mac32 >>= 8;
+    macBuf[0] = (unsigned char)mac32;
+    show("MMH32 MAC", macBuf, 4);
+    printf("\n");
+    return 0;
+}
+
+```
+
+Here is the output produced by the program:
+
+```
+Example of MMH16 computation
+message
+4e 6f 77 20 69 73 20 74 68 65 20 74 69 6d 65 2e
+key
+35 2c cf 84 95 ef d7 df b8 f5 74 05 95 eb 98 d6
+pad
+ae 07
+x 4e6f y 352c sum 104a7614
+x 7720 y cf84 sum f9bac294
+x 6973 y 95ef sum ce0a23f1
+x 2074 y d7df sum c8f3d4fd
+x 6865 y b8f5 sum abfb55a6
+x 2074 y 7405 sum bab087ea
+x 696d y 95eb sum 8f00bff9
+x 652e y 98d6 sum 663aa46d
+sum mod F4, truncated to 16 bits: 3e33
+pad variable: ae07
+mmh16 value: ec3a
+MMH16 MAC
+ec 3a
+Example of MMH32 computation
+message
+4e 6f 77 20 69 73 20 74 68 65 20 74 69 6d 65 2e
+key
+35 2c cf 84 95 ef d7 df b8 f5 74 05 95 eb 98 d6
+eb 98
+pad
+bd e1 89 7b
+x 4e6f y 352c sum 104a7614
+x 7720 y cf84 sum f9bac294
+x 6973 y 95ef sum ce0a23f1
+x 2074 y d7df sum c8f3d4fd
+x 6865 y b8f5 sum abfb55a6
+x 2074 y 7405 sum bab087ea
+x 696d y 95eb sum 8f00bff9
+x 652e y 98d6 sum 663aa46d
+sum mod F4, truncated to 16 bits: 3e33
+pad variable: bde1
+mmh16 value: fc14
+x 4e6f y cf84 sum f125323c
+x 7720 y 95ef sum bfca091c
+x 6973 y d7df sum af427949
+x 2074 y b8f5 sum a640e84d
+x 6865 y 7405 sum d590b646
+x 2074 y 95eb sum c81e04c2
+x 696d y 98d6 sum 9da1dde0
+x 652e y eb98 sum 95912b30
+sum mod F4, truncated to 16 bits: 959f
+pad variable: 897b
+mmh16 value: 1f1a
+MMH32 MAC
+fc 14 1f 1a
+```
+
+
+
+# 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.179**
+
+(11/2005)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+IPCablecom
+
+---
+
+**IPCablecom support for multimedia**
+
+ITU-T Recommendation J.179
+
+
+
+# IPCablecom support for multimedia
+
+# Summary
+
+This Recommendation describes the deployment of general Multimedia services by providing a technical definition of several IP-based signalling interfaces that leverage core QoS and policy management capabilities native to CableModems. Multimedia services are defined as IP-based services (e.g., online gaming, videoconferencing, streaming media, etc.) requiring QoS-based network resources (as contrasted with services such as web browsing, email, instant messaging and file-sharing that are commonly provided using best-effort flows). While telephony or voice-based services are not specifically excluded from this definition, the IPCablecom-T set of Recommendations provide coverage specific to this type of service delivery and, therefore, those Recommendations should be consulted as appropriate.
+
+## Source
+
+ITU-T Recommendation J.179 was approved on 29 November 2005 by ITU-T Study Group 9 (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    |
+| 2.1 | Normative references.....                                          | 1    |
+| 2.2 | Informative references.....                                        | 1    |
+| 3   | Terms and Definitions .....                                        | 2    |
+| 4   | Abbreviations, acronyms and conventions .....                      | 2    |
+| 4.1 | Abbreviations and acronyms .....                                   | 2    |
+| 4.2 | Conventions .....                                                  | 4    |
+| 5   | Technical overview.....                                            | 4    |
+| 5.1 | QoS background .....                                               | 4    |
+| 5.2 | Architecture .....                                                 | 8    |
+| 6   | Authorization interface description .....                          | 16   |
+| 6.1 | Gates: The framework for QoS control .....                         | 17   |
+| 6.2 | Gate transitions .....                                             | 23   |
+| 6.3 | COPS profile for IPCablecom multimedia.....                        | 29   |
+| 6.4 | Gate control protocol message formats .....                        | 31   |
+| 6.5 | Gate control protocol operation.....                               | 55   |
+| 7   | Event messaging interface description .....                        | 64   |
+| 7.1 | Introduction .....                                                 | 64   |
+| 7.2 | Record keeping server requirements .....                           | 66   |
+| 7.3 | General IPCablecom multimedia network element requirements.....    | 66   |
+| 7.4 | Event messages for IPCablecom multimedia .....                     | 68   |
+| 7.5 | Event messaging attributes for IPCablecom multimedia .....         | 73   |
+| 7.6 | RADIUS accounting protocol .....                                   | 81   |
+| 8   | Security requirements .....                                        | 83   |
+| 8.1 | CMTS – CM QoS interface (pkt-mm-1) .....                           | 83   |
+| 8.2 | Policy server – CMTS COPS interface (pkt-mm-2).....                | 83   |
+| 8.3 | Application manager – Policy server COPS interface (pkt-mm-3)..... | 84   |
+| 8.4 | Policy Server – RKS Event Message Interface (pkt-mm-4) .....       | 84   |
+| 8.5 | CMTS – RKS Event Message Interface (pkt-mm-5) .....                | 85   |
+| 9   | Mapping a FlowSpec traffic profile to DOCSIS .....                 | 85   |
+| 9.1 | Mapping FlowSpecs to DOCSIS scheduling types .....                 | 85   |
+| 9.2 | Mapping FlowSpecs to DOCSIS traffic parameters .....               | 86   |
+| 9.3 | DOCSIS upstream parameters.....                                    | 88   |
+| 9.4 | DOCSIS downstream parameters.....                                  | 91   |
+
+|                                                               | Page |
+|---------------------------------------------------------------|------|
+| 10 Message flows .....                                        | 93   |
+| 10.1 Basic message sequence .....                             | 94   |
+| 10.2 Detailed message sequence .....                          | 96   |
+| 11 Issues for future study.....                               | 115  |
+| Appendix I – Background information .....                     | 116  |
+| I.1 Introduction .....                                        | 116  |
+| I.2 IPCablecom multimedia objectives and scope .....          | 117  |
+| I.3 IPCablecom multimedia framework.....                      | 119  |
+| I.4 Proxied QoS with policy push (Scenario 1) .....           | 124  |
+| I.5 Client-requested QoS with policy-push (Scenario 2).....   | 132  |
+| I.6 Client-requested QoS with policy-pull (Scenario 3) .....  | 139  |
+| I.7 Comparison of IPCablecom-T and IPCablecom multimedia..... | 141  |
+| Appendix II – Guidelines for version number assignment .....  | 145  |
+
+# IPCablecom support for multimedia
+
+# 1 Scope
+
+This Recommendation supports the deployment of general Multimedia services by providing a technical definition of several IP-based signalling interfaces that leverage core QoS and policy management capabilities native to CableModems. Multimedia services are defined as IP-based services (e.g., online gaming, videoconferencing, streaming media, etc.) requiring QoS-based network resources (as contrasted with services such as web browsing, e-mail, instant messaging and file-sharing that are commonly provided using best-effort flows). While telephony or voice-based services are not specifically excluded from this definition, the IPCablecom-T set of Recommendations provides coverage specific to this type of service delivery and, therefore, those Recommendations should be consulted as appropriate.
+
+# 2 References
+
+## 2.1 Normative 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 J.112 Annex B (2004), *Data-over-cable service interface specifications: Radio-frequency interface specification*.
+- [2] IETF RFC 1305 (1992), *Network Time Protocol (Version 3) Specification, Implementation and Analysis*.
+- [3] IETF RFC 2210 (1997), *The Use of RSVP with IETF Integrated Services*.
+- [4] IETF RFC 2211 (1997), *Specification of the Controlled-Load Network Element Service*.
+- [5] IETF RFC 2212 (1997), *Specification of Guaranteed Quality of Service*.
+- [6] IETF RFC 2474 (1998), *Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers*.
+- [7] IETF RFC 2748 (2000), *The COPS (Common Open Policy Service) Protocol*.
+- [8] IETF RFC 2866 (2000), *RADIUS Accounting*.
+- [9] ITU-T Recommendation J.163 (2005), *Dynamic quality of service for the provision of real-time services over cable television networks using cable modems*.
+- [10] ITU-T Recommendation J.164 (2005), *Event message requirements for the support of real-time services over cable television networks using cable modems*.
+- [11] ITU-T Recommendation J.170 (2005), *IPCablecom security specification*.
+- [12] ITU-T Recommendations J.125 (2004), *Link privacy for cable modem implementations*.
+
+## 2.2 Informative references
+
+- [13] IETF RFC 1633 (1994), *Integrated Services in the Internet Architecture: An Overview*.
+
+- [14] IETF RFC 2205 (1997), *Resource ReSerVation Protocol (RSVP) – Version 1 Functional Specification*.
+- [15] IETF RFC 2216 (1997), *Network Element Service Specification Template*.
+- [16] IETF RFC 2475 (1998), *An Architecture for Differentiated Services*.
+- [17] IETF RFC 2670 (1999), *Radio Frequency (RF) Interface Management Information Base for MCNS/DOCSIS Compliant RF Interfaces*.
+- [18] IETF RFC 2753 (2000), *A Framework for Policy-based Admission Control*.
+- [19] IETF RFC 3084 (2001), *COPS Usage for Policy Provisioning (COPS-PR)*.
+- [20] IETF RFC 3175 (2001), *Aggregation of RSVP for IPv4 and IPv6 Reservations*.
+- [21] CableLabs (<http://www.cablemodem.com/specifications>).
+- [22] IETF RFC 2751 (2000), *Signaled Preemption Priority Policy Element*.
+
+# 3 Terms and Definitions
+
+This Recommendation defines the following terms:
+
+**3.1 client type 1:** Client type 1 represents existing "legacy" endpoints (e.g., PC applications, gaming consoles) which lack specific QoS awareness or signalling capabilities. This Client knows nothing about CableModem, IPCable2Home, or IPCablecom messaging, and hence no related requirements can be placed upon it. Such clients may range from simple analog audio and video presentation devices to complex networked peripherals and consumer electronics, such as set-top boxes or gaming consoles. This Client communicates with an Application Manager to request service, and does not request QoS resources directly from the operator access network. This Recommendation supports only client type 1.
+
+**3.2 client type 2:** Client type 2 is similar to an IPCablecom-T telephony MTA in that it supports QoS signalling based on IPCablecom DQoS. This Client is aware of IPCablecom Multimedia QoS, and communicates with an Application Manager to request service and obtain a token for access-network resources. The client then presents this token when requesting QoS resources from the access network (pkt-mm-1, pkt-mm-6). This Recommendation's support for client type 2 remains for further study.
+
+**3.3 client type 3:** Client type 3 requests QoS based on RSVP without Application Manager interaction. This Client is aware of IETF standards-based RSVP and uses this protocol to request QoS resources from the access network directly from the CMTS. This Recommendation's support for client type 3 remains for further study.
+
+**3.4 DOCSIS:** Describes a specific CableModem technology as developed by Cable Television Laboratories, Inc. ("CableLabs") located at: <http://www.cablemodem.com/specifications/>. The international version is defined in Annex B/J.112.
+
+**3.5 IPCablecom-T:** The suite of IPCablecom ITU-T Recommendations that support telephone service.
+
+# 4 Abbreviations, acronyms and conventions
+
+## 4.1 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations:
+
+AM                      Application Manager (a system that interfaces to Policy Server(s) for requesting QoS-based service on behalf of an end-user or network management system)
+
+|                 |                                                                                                                                                                        |
+|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| BCID            | Billing Correlation ID (defined in the IPCablecom Event Messaging Recommendation)                                                                                      |
+| CM              | Cable Modem                                                                                                                                                            |
+| CMS             | Call Management Server                                                                                                                                                 |
+| CMTS            | Cable Modem Termination System                                                                                                                                         |
+| COPS            | Common Open Policy Service (defined in RFC 2748)                                                                                                                       |
+| DQoS            | Dynamic Quality-of-Service                                                                                                                                             |
+| DSx (Messaging) | J.112 Annex B QoS signalling mechanism providing Dynamic Service Add, Change and Delete semantics                                                                      |
+| FQDN            | Fully Qualified Domain Name                                                                                                                                            |
+| HFC             | Hybrid Fibre/Coax                                                                                                                                                      |
+| IETF            | Internet Engineering Task Force                                                                                                                                        |
+| IP              | Internet Protocol                                                                                                                                                      |
+| KDC             | Key Distribution Centre                                                                                                                                                |
+| MG              | Media Gateway                                                                                                                                                          |
+| MGC             | Media Gateway Controller                                                                                                                                               |
+| MTA             | Multimedia Terminal Adapter                                                                                                                                            |
+| NAT             | Network Address Translation                                                                                                                                            |
+| PDP             | Policy Decision Point (defined in RFC 2753)                                                                                                                            |
+| PEP             | Policy Enforcement Point (defined in RFC 2753)                                                                                                                         |
+| PS              | Policy Server                                                                                                                                                          |
+| PSTN            | Public Switched Telephone Network                                                                                                                                      |
+| QoS             | Quality of Service                                                                                                                                                     |
+| RADIUS          | Remote Authentication Dial-In User Service (defined in RFC 2138 and RFC 2139)                                                                                          |
+| RAP             | Resource Allocation Protocol (Working Group in the IETF – responsible for the definition and maintenance of the COPS protocol)                                         |
+| RCD             | Resource Control Domain                                                                                                                                                |
+| RFC             | Request for Comments (technical policy documents approved by the IETF which are available at <a href="http://www.ietf.org/rfc.html">http://www.ietf.org/rfc.html</a> ) |
+| RFI             | Radio Frequency Interface (specification defining MAC and Physical layer interfaces between CMTS and CM network elements)                                              |
+| RKS             | Record Keeping Server                                                                                                                                                  |
+| RSVP            | Resource ReSerVation Protocol (defined in RFC 2205)                                                                                                                    |
+| RSVP+           | IPCablecom profile and extension of RSVP (defined in the IPCablecom DQoS Recommendation)                                                                               |
+| SCD             | Session Control Domain                                                                                                                                                 |
+| S-MTA           | Standalone MTA (a single node that contains an MTA and a non-DOCSIS MAC (e.g., Ethernet))                                                                              |
+
+|        |                                                                                                                        |
+|--------|------------------------------------------------------------------------------------------------------------------------|
+| TCP    | Transmission Control Protocol                                                                                          |
+| TLV    | Type-Length-Value (technique used in formatting protocol elements)                                                     |
+| UDP    | User Datagram Protocol (a connectionless protocol built upon Internet Protocol (IP))                                   |
+| UGS    | Unsolicited Grant Service (Annex B/J.112 QoS scheduling type used for constant bit rate services (e.g., voice codecs)) |
+| UGS/AD | Unsolicited Grant Service with Activity Detection                                                                      |
+| VoIP   | Voice over IP                                                                                                          |
+| VPN    | Virtual Private Network                                                                                                |
+
+## 4.2 Conventions
+
+Throughout this Recommendation, the words that are used to define the significance of particular requirements are capitalized. These words are:
+
+|              |                                                                                                                                                                                                                                                                                 |
+|--------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| "MUST"       | This word or the adjective "REQUIRED" means that the item is an absolute requirement of this Recommendation.                                                                                                                                                                    |
+| "MUST NOT"   | This phrase means that the item is an absolute prohibition of this Recommendation.                                                                                                                                                                                              |
+| "SHOULD"     | This word or the adjective "RECOMMENDED" means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighed before choosing a different course.                            |
+| "SHOULD NOT" | This phrase means that valid reasons may exist, in particular circumstances, when the listed behaviour is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behaviour described with this label. |
+| "MAY"        | This word, or the adjective "OPTIONAL", means that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product, for example; another vendor may omit the same item.                  |
+
+# 5 Technical overview
+
+This clause consists of background material which some readers may find to be a useful context for the detailed protocol interface Recommendations that follow. The intent in this clause is to provide a high-level overview of the IPCablecom Multimedia architecture and the fundamental technologies upon which it is based. For more details on Multimedia architecture, see Appendix I.
+
+## 5.1 QoS background
+
+As noted throughout this Recommendation, one of the primary features of the IPCablecom Multimedia service framework lies in the fact that it provides IP-layer access to sophisticated QoS capabilities defined in Annex B/J.112 and IPCablecom-T. This subclause provides a brief overview of these capabilities as preparatory background for the detailed QoS policy and resource management discussion that follows.
+
+### 5.1.1 Annex B/J.112 QoS summary
+
+The Annex B/J.112 RFI Recommendation [1] defines a set of QoS facilities based on a fundamental network resource management construct known as a Service Flow. A Service Flow is defined as "a MAC-layer transport service which:
+
+- 1) provides unidirectional transport of packets from the upper layer service entity to the RF; and
+- 2) shapes, polices, and prioritizes traffic according to QoS traffic parameters defined for the flow."
+
+In addition to this primary abstraction facilitating the reservation and scheduling of shared access network resources on a per-flow basis, a number of tangible supporting constructs are defined and used to manage these resources. Two of these are:
+
+- Service Flow Encodings: type-length-value (TLV) encoded parameters used to define QoS parameters associated with a Service Flow.
+- Classifier: type-length-value (TLV) encoded IP, Ethernet and IEEE802.1p/q parameters used to define and limit the scope of a flow in terms of originating and terminating endpoints.
+
+While Annex B/J.112 supports provisioned (i.e., static, long-lived Service Flows that are established during the CM registration process) and dynamic (i.e., transient Service Flows that are added, modified and deleted on an as-needed basis) QoS models, the IPCablecom Multimedia framework is primarily concerned with the dynamic variety as this allows for optimal network resource management through statistical multiplexing as service requirements demand.
+
+Service Flow management is performed through MAC-layer DOCSIS Dynamic Service Add/Change/Delete (DSA/DSC/DSD) messaging, which may be initiated either by the CM or by the CMTS. DSA and DSC transactions take the form of a three-way exchange in which a request (REQ) is followed by a response (RSP) which is then acknowledged (ACK). DSD messages are simple two-way exchanges. A specific attribute known as a Confirmation Code is provided in each DSx response message and indicates the success or failure status of a transaction.
+
+One important point to note in reviewing the QoS capabilities provided in Annex B/J.112 is that upstream and downstream Service Flows receive fundamentally different treatment at the CMTS. This is a result of the fact that upstream RF channels are contentious, shared-access mediums, taking the topological form of a many-to-one relationship between multiple CMs and a single CMTS. Conversely, the downstream RF channel behaves much more akin to a traditional IP router in which packets arrive (either from the access network or over backbone trunks), are queued, and are forwarded to one or more destinations. Consequently, distinct QoS mechanisms are applied depending upon whether a particular unidirectional Service Flow is oriented in the upstream or downstream direction.
+
+Upstream Service Flows may be defined with one of five service flow scheduling types:
+
+- Best-Effort: a standard contention-based resource management strategy in which transmit opportunities are granted on a first-come-first-served basis, albeit under the coordination of the CMTS scheduler. This scheduling type may be supplemented with QoS characteristics in which, for example, maximum rate limits are applied to a particular Service Flow.
+- Non-Real-Time Polling: a reservation-based resource management strategy in which a particular CM is polled on a fixed interval to determine whether data has been queued for transmission on a particular service flow, and, if so, a transmission opportunity or grant for that service flow is provided by the scheduler.
+- Real-Time Polling: analogous to the Non-Real-Time-Polling scheduling type, except that the fixed polling interval is typically very short (<500 ms). Polling scheduling types are
+
+most suitable for variable-bit-rate traffic that has inflexible latency and throughput requirements.
+
+- Unsolicited Grant: a reservation-based resource management strategy in which a fixed-size grant is provided to a particular Service Flow at (nearly) fixed intervals without additional polling or interaction. This scheduling type is most suitable for constant bit-rate traffic and eliminates much of the protocol overhead associated with the polling types.
+- Unsolicited Grant with Activity Detection: a reservation-based resource management strategy that represents a hybrid of the polling and unsolicited grant scheduling types in which fixed grants are provided at (nearly) fixed intervals so long as data is queued for transmission. During periods of inactivity, this scheduling type reverts to a polling mode in order to conserve unused bandwidth.
+
+Due to the unique nature and specialized characteristics of each of these scheduling types, specific QoS parameters are associated with each. These parameters are outlined in detail in the following clause.
+
+Downstream Service Flows are defined using the same set of QoS parameters that are associated with the Best-Effort scheduling type on the upstream.
+
+Regardless of the orientation of the flow or the particular scheduling type requested, all dynamic Service Flows proceed through three logical states, summarized below. While certain optimized signalling scenarios allow for a so-called "single-phase" commit operation, the request still proceeds logically through all three phases as it is serviced at the CMTS.
+
+- Authorized: requests are authenticated and network policy rules are applied resulting in an authorization envelope forming the boundary of subsequent reservation requests.
+- Admitted (or Reserved): an inactive Service Flow is constructed and resources are reserved by the scheduler so that subsequent activation requests are guaranteed to succeed; reserved resources may be used by best-effort traffic (from the same or different CMs) until committed.
+- Active (or Committed): the Service Flow is activated, along with corresponding Classifiers; QoS-enhanced packets are now able to traverse the flow.
+
+NOTE – In a literal sense, DOCSIS does not define "states", but, rather, "attributes" of Service Flows which are completely replaced with each DSC transaction. The states described here are a logical construct used in a conceptual model describing the resource management process performed on the CMTS. Also, the DOCSIS RFI Recommendation standardizes upon the terms "admitted" and "active" in defining the attributes of a service flow, while IPCablecom has adopted the equivalent terms "reserved" and "committed" in characterizing Gate states.
+
+While DOCSIS does not define a specific authorization procedure to be applied to DSx messages, it does provide protocol support through a facility known as an Authorization Block for service-specific authorization schemes. Any credentials or authorization tokens that are presented via the Authorization Block are forwarded to an appropriate authorization module prior to the processing of the DSx request on the CMTS. IPCablecom makes extensive use of this authorization mechanism as described below.
+
+### 5.1.2 IPCablecom-T QoS Summary
+
+While the Annex B/J.112 RFI Recommendation defines the fundamental QoS mechanisms that form the core of the IPCablecom DQoS model, the IPCablecom DQoS Recommendation [9] augments these capabilities with a COPS-based policy management framework. Just as the Service Flow represents the primary abstraction in the Annex B/J.112 QoS model, the Gate plays a comparably significant role in the IPCablecom DQoS scheme. A Gate defines a resource authorization envelope consisting of IP-level QoS parameters as well as classifiers defining the scope of Service Flows that may be established against the Gate. In accordance with the
+
+Annex B/J.112 authorization mechanisms described above, only DSx requests which conform to the following general relation on a parameter-by-parameter basis will be granted:
+
+$$\text{Authorized Envelope} \geq \text{Reserved Envelope} \geq \text{Committed Envelope}$$
+
+Based on this policy management model, IPCablecom-T defines a pre-authorization scheme in which network resources are authorized in advance of DSx messaging that requests establishment of a corresponding Service Flow. Consequently, the COPS interface used to install and manage Gates corresponds more closely with the COPS-PR model defined in RFC 3084 [19] than with the standard COPS scheme specified in RFC 2748 [7]. Also, in order to install and manage these Gates, the IPCablecom DQoS Recommendation defines a set of COPS client-specific objects which constitute the primitives of a Gate Control signalling interface between the CMS and the CMTS.
+
+Specifically, the CMS may be logically decomposed into a Call Agent, responsible for telephony call-state maintenance, and a Gate Controller, which receives authorization requests from the Call Agent (through an internal interface) and installs policy decisions in the form of Gates on the CMTS. In the IPCablecom Multimedia model, this decomposition is formalized through two separate network elements, the Policy Server (analogous to the IPCablecom-T Gate Controller) and the Application Manager (defining service-specific functionality similar to the Call Agent in the IPCablecom-T model).
+
+As an illustration of this pre-authorization model and the use of the Gate Control interface on the CMTS, a typical single-zone (i.e., using a single CMS) on-net IPCablecom-T call flow proceeds as follows (some of these steps would normally happen in parallel):
+
+- E-MTA<sub>o</sub> boots, provisions and registers with CMS;
+- CMS issues request to E-MTA<sub>o</sub> for notification of off-hook event and dialed-digits;
+- E-MTA<sub>t</sub> boots, provisions and registers with CMS;
+- CMS issues request to E-MTA<sub>t</sub> for notification of off-hook event and dialed-digits;
+- E-MTA<sub>o</sub> goes off-hook, notifies CMS and delivers dialed-digits;
+- CMS issues a request to E-MTA<sub>o</sub> to create a new logical connection and retrieves SDP<sub>o</sub>;
+- CMS issues a request to E-MTA<sub>t</sub> to create a new logical connection and retrieves SDP<sub>t</sub>;
+- CMS installs a Gate on CMTS<sub>o</sub> and retrieves corresponding GateID<sub>o</sub> token;
+- CMS installs a Gate on CMTS<sub>t</sub> and retrieves corresponding GateID<sub>t</sub> token;
+- CMS issues a request (with GateID<sub>o</sub>) to E-MTA<sub>o</sub> to reserve resources and play ringback;
+- E-MTA<sub>o</sub> issues a DSA-REQ to CMTS<sub>o</sub> to establish service flows and reserve resources;
+- CMS issues a request (with GateID<sub>t</sub>) to E-MTA<sub>t</sub> to reserve resources and play an alerting tone;
+- E-MTA<sub>t</sub> issues a DSA-REQ to CMTS<sub>t</sub> to establish service flows and reserve resources;
+- E-MTA<sub>t</sub> goes off-hook and notifies CMS;
+- CMS issues a request to E-MTA<sub>o</sub> to stop playing ringback, commit resources and cut-through media path;
+- E-MTA<sub>o</sub> issues a DSC-REQ to CMTS<sub>o</sub> to commit resources;
+- CMS issues a request to E-MTA<sub>t</sub> to commit resources and cut-through media path;
+- E-MTA<sub>t</sub> issues a DSC-REQ to CMTS<sub>t</sub> to commit resources;
+- Call proceeds.
+
+In contrast to the IPCablecom model in which the client device (i.e., E-MTA) initiates the resource reservation and activation procedures, the IPCablecom Multimedia resource management model allows for the proxying of these steps on behalf of the endpoint through an enhanced Gate Control interface.
+
+This concludes this brief review of Annex B/J.112 and IPCablecom QoS fundamentals. For further details related to either of these considerably complex topics, please consult the respective primary sources [1] and [9]. The next clause provides a summary overview of the IPCablecom Multimedia architecture including each of the primary network elements and associated interfaces as further preparation for the technical protocol Recommendation that follows.
+
+## 5.2 Architecture
+
+Appendix I describes an architecture framework and reference model for IPCablecom Multimedia. This Recommendation applies the model contained in the architectural framework and adds normative requirements to provide a scaleable, interoperable solution suitable for deploying IPCablecom Multimedia services.
+
+### 5.2.1 Client types
+
+The IPCablecom Multimedia technical report defines three kinds of client types:
+
+- Client Type 1, which represents existing "legacy" endpoints (e.g., PC applications, gaming consoles) that lack specific QoS awareness or signalling capabilities. This client has no awareness of CableModem, IPCable2Home, or IPCablecom messaging, and hence no related requirements can be placed upon it. Client Type 1 communicates with an Application Manager to request service, and does not (cannot) request QoS resources directly from the cable operator access network.
+- Client Type 2 is similar to an IPCablecom-T telephony MTA in that it supports QoS signalling based on the IPCablecom DQoS Recommendation.
+- Client Type 3 directly requests QoS treatment from the access network without Application Manager interaction. This client is aware of IETF standards-based RSVP and uses this protocol to request access network QoS resources directly from the CMTS.
+
+In this version of the Recommendation support is limited to Client Type 1. Consequently, this release of this Recommendation supports only Scenario 1, the "Proxied QoS with Policy Push" scenario, described in Appendix I. Under this scenario, the Application Manager is responsible for requesting QoS resources on behalf of the client, and a Policy Server pushes the request down to the CMTS, which is the device actually responsible for setting up and managing the DOCSIS service flows required by the application.
+
+### 5.2.2 IPCablecom multimedia devices
+
+In addition to the client (which typically resides at a subscriber's premises), IPCablecom Multimedia requires several network elements residing in, or accessible to and trusted by, the cable operator's network. In the process of describing these network elements throughout this Recommendation we borrow heavily from standard IETF terminology and concepts. For a more thorough treatment of the overall IPCablecom Multimedia architecture, including a discussion of underlying requirements and objectives, please refer to Appendix I.
+
+Since COPS [7] and COPS-PR [19] each use the terms Policy Enforcement Point (PEP) and Policy Decision Point (PDP) in substantially different interaction scenarios, and since IPCablecom Multimedia adds further nuances to these concepts (particularly in the definition of the Policy Server), it is occasionally confusing to think solely in terms of PEPs and PDPs to understand the responsibilities of the various components of the IPCablecom Multimedia architecture. To attempt to alleviate this confusion, portions of this Recommendation employ the notion of a Service Control Domain and a Resource Control Domain to draw distinctions in the type of policy that is being defined and enforced.
+
+The Resource Control Domain (RCD) may be defined as a logical grouping of elements that provide connectivity and network resource level policy management along the packet forwarding
+
+paths to and from an end host. The RCD consists of CMTS and Policy Server entities whose responsibilities include management of resources along the packet forwarding paths.
+
+The Service Control Domain (SCD) is defined as a logical grouping of elements that offer applications and content to service subscribers. The Application Manager resides in the SCD. Note that there may be one or more SCDs related to a single RCD. Conversely, each RCD may interact with one or more SCDs.
+
+![Diagram of Session and resource control domains showing the hierarchy from SCD to RCD to CMTS.](724c7777b608e53be38b12b6fb3c43bc_img.jpg)
+
+The diagram illustrates the relationship between the Service Control Domain (SCD) and the Resource Control Domain (RCD). The SCD is represented by a dashed box at the top, containing an 'Application manager' which in turn contains an 'App state controller' and a 'PDP'. The RCD is represented by a dashed box below the SCD, containing a 'Policy server' which contains a 'PEP' and a 'PDP'. Below the RCD is a box for 'CMTS' which contains a 'PEP' and 'J.112 QoS'. Double-headed arrows indicate bidirectional communication between the Application manager and the Policy server, and between the Policy server and the CMTS. The label 'J.179\_F01' is located at the bottom right of the diagram.
+
+Diagram of Session and resource control domains showing the hierarchy from SCD to RCD to CMTS.
+
+**Figure 1/J.179 – Session and resource control domains**
+
+In the IPCablecom Multimedia architecture, the fundamental role of the Application Manager is to maintain an application's session-level state and to enforce any Service Control Domain (SCD) policies against client-driven session requests. If the client's session requests pass the Application Manager's SCD policy checks, the Application Manager converts the session request into a resource request and passes it on to the Policy Server for Resource Control Domain (RCD) policy checks. If the resource request fails the RCD policy check the Policy Server denies the resource request and the Application Manager consequently denies the client's session request. If, however, the resource request passes the Policy Server's RCD checks, the Policy Server forwards the request on to the CMTS for network-level admission control.
+
+Fundamentally, the roles of the various IPCablecom Multimedia components are:
+
+- The Application Manager is responsible for application or session-level state and for applying SCD policy.
+- The Policy Server is responsible for applying RCD policy and for managing relationships between Application Managers and CMTSs.
+- The CMTS is responsible for performing admission control and managing network resources through DOCSIS Service Flows.
+
+It may be useful here to clarify our use of the terms "admission control" and "policy authorization". For the purposes of this Recommendation, admission control is generally understood as the process of managing a finite pool of network-level resources (e.g., access network bandwidth, scheduler DOCSIS minislots, or CMTS resources supporting Gates and timers, etc.) and admitting requests against this pool. For performance reasons, admission control is usually performed directly on network elements managing the packet forwarding path (such as the CMTS), though some sophisticated Policy Server implementations may choose to maintain the state associated with network resources, thus supplementing and contributing to the admission control process.
+
+In contrast, policy authorization is used here to describe higher-level aggregate usage policies (e.g., number of concurrent authorizations for a particular subscriber or service) which constitute a cable operator's network management strategy. Policy authorization is almost always defined and enforced at the Policy Server.
+
+The rest of this clause describes each of these architectural components and their associated interfaces in more detail.
+
+#### **5.2.2.1 Application Manager (AM)**
+
+As noted in the preceding summary, the Application Manager is a network entity that defines SCD policies, coordinates subscriber-initiated requests for application sessions with access to the resources needed to meet those requests, and maintains application-level state.
+
+The AM may reside on the cable operator's network or it may reside outside this domain and interact with the cable operator network via a particular trust relationship (typically defined by and enforced on the basis of a Service Level Agreement). Similarly, the AM may be under the direct control of the operator or it may be controlled by a third party. Any given Application Manager may communicate with one or more Policy Servers on the operator's network; likewise, one or more Application Managers may communicate with any given Policy Server on the operator's network (so long as an appropriate trust relationship exists).
+
+In most anticipated service deployment scenarios, the Application Manager will communicate with a client via a signalling protocol that is beyond the scope of this Recommendation. Using this unspecified protocol, the AM authenticates and authorizes client requests based on Service Control Domain policies. For client requests that pass these checks, the AM determines the particular QoS parameters necessary to deliver the service to the client, based on its knowledge of the requested service. It then sends a request for these resources to the appropriate Policy Server, which may deny the request based on network or RCD policy or may pass the request on to the CMTS for admission control and enforcement.
+
+#### **5.2.2.2 Policy Server (PS)**
+
+As discussed in RFC 2753 [18], the policy management framework underlying IPCablecom Multimedia is based on the work of the IETF's Resource Allocation Protocol (RAP) working group. Since the Policy Server is situated between the Application Manager and the CMTS, it simultaneously plays a dual role as a "proxy" for AM-initiated session requests and as a "sentry" for defining and enforcing Resource Control Domain policy.
+
+As described in [18] and in keeping with the IPCablecom-T DQoS model, the Policy Server serves as Policy Decision Point (PDP) in relation to the CMTS in that the Policy Server implements cable operator-defined authorization and resource-management procedures. Conversely, the Policy Server assumes the role of Policy Enforcement Point (PEP) in relation to the Application Manager as it proxies Gate Control messages to and from the CMTS element.
+
+To revisit the interaction scenario, the Application Manager issues policy requests to the Policy Server. The Policy Server acts as a "sentry" for these requests, and applies a set of policy rules that have been pre-provisioned by the cable operator. Upon passing the checks, the Policy Server then acts as a "proxy" with respect to the Application Manager and the CMTS, forwarding the policy request and returning any associated response. Each policy request transaction must be processed individually.
+
+Policy decisions may be based on a number of factors, such as:
+
+- Parameters associated with the request and the status of available resources;
+- Identity of the particular client and associated profile information;
+- Application parameters;
+- Security considerations;
+- Time-of-day.
+
+The primary functions of the Policy Server include:
+
+- A policy decision request mechanism, invoked by Application Managers;
+- A policy decision request 'policing' mechanism, enforcing installed Policy Rules;
+- A policy decision delivery mechanism, used to install policy decisions on the CMTS;
+- A mechanism to allow for the proxying of QoS management messages to the CMTS on behalf of the Application Manager;
+- An event recording interface to a Record Keeping Server that is used to log policy requests, which may in turn be correlated with network resource usage records.
+
+Since the Policy Server functions as a proxy between the AM and CMTS elements (with complementary client and server interfaces), some cable operators may elect to deploy multiple layers of Policy Servers and to delegate certain policy decisions among these servers in order to satisfy requirements associated with scalability and fault-tolerance.
+
+##### **5.2.2.2.1 Stateful and stateless policy servers**
+
+There are two basic classes of Policy Servers; Stateful and Stateless. A Stateless Policy Server is a slight misnomer since it does maintain enough state information to map Application Manager requests to the proper CMTS and maintains COPS session state, while a pure Stateless Policy Server maintains no state on any of the media sessions. Stateful Policy Servers come in several varieties: some participate in admission control and thus monitor the QoS attributes of active media sessions, some leave QoS and admission control to the CMTS but monitor time-based or volume-based service requests from the Application Manager, and some Policy Servers are somewhere between these extremes.
+
+The reason there is a variety of Policy Server types is that there is a variety of environments that operators are trying to support. For example, some operators may wish to support IPCablecom Multimedia over the same CMTSs that they use for IPCablecom telephony, and they may want a single CMS/Policy Server that has a more global view of the network resources being used. On the other hand, some operators may wish to run an IPCablecom Multimedia-only environment, or they may utilize simpler CMTS-driven mechanisms for partitioning IPCablecom Multimedia and telephony resources. These simpler configurations have more modest requirements on the amount of state that a Policy Server maintains.
+
+Policy Server state requirements can also be driven by the level of trust between the Policy Server and Application Manager; a Stateful Policy Server can more readily police Application Manager session control behaviour than can a Stateless Policy Server. So, a Stateful Policy Server may be more appropriate for operators supporting third party Application Managers. Other operators may rely on economics to enforce their trust relationships with Application Managers, or they may control the Application Managers themselves. In such cases, a Stateless Policy Server may be more appropriate.
+
+Since it is impossible to categorize all the various components of media session and network QoS state that a Policy Server is maintaining, the protocol is designed to be independent of this complexity. A Stateful Policy Server gleans IPCablecom Multimedia media session information from the Application Manager requests that it proxies; any other information it requires is gathered
+
+via mechanisms that are outside the scope of this Recommendation. The CMTS and the Application Manager make no distinction as to the type of Policy Server to which they are connected, and the protocol is designed in such a manner that the type of Policy Server is transparent to the end point. The type of Policy Server is only of importance to the operator.
+
+Since some types of Policy Servers attempt to assist with admission control and may have a larger view of the network and its resources, additional state synchronization issues may arise in design in a network which contains more than one of these types of Policy Servers. It is the responsibility of the operator to ensure that the efforts of these Policy Servers are not undermined by a network that includes other autonomous Policy Servers.
+
+##### **5.2.2.2.2 Modification of requests and responses by policy servers**
+
+Although nominally a part of the Resource Control Domain, the Policy Server can be an intermediary between the Service and the Resource Control Domains, in addition to its normal role of implementing operator-defined authorization and resource management procedures. In either of these capacities it may modify the incoming request before forwarding it to the CMTS.
+
+In acting as an intermediary between the SCD and RCD, the Policy Server may translate fields from formats or scales used in the SCD into formats or scales used in the RCD. For example, the Policy Server may modify the "priority" of a request coming from an Application Manager (especially important to do so for an AM outside of the MSO network) so that this priority field uses a consistent scale throughout the operator's RCD. In its capacity as an intermediary, the Policy Server may use bidirectional translation – in other words, it should translate requests from the AM to the CMTS and "untranslate" the responses from the CMTS to the AM. This capability can be supported by stateful policy servers by remembering the original request, and it can be supported by stateless Policy Servers if the translation function is invertible.
+
+Modification of certain objects, specifically the Classifier and Traffic Profile objects, may cause operational problems in the originating AM. As such, these objects **MUST NOT** be modified by the policy server. Aside from these exceptions, all other objects may be policed and modified at the PS's discretion, based on provisioned policy rules.
+
+#### **5.2.2.3 Cable Modem Termination System (CMTS)**
+
+In describing the role of the CMTS network element, it is important to consider the relation among CableModem, IPCablecom-T and IPCablecom Multimedia functionality. While each of these suites of Recommendations addresses a specific set of functional requirements, each has also been defined in such a way that corresponding implementations may be constructed in a modular manner; either IPCablecom-T or IPCablecom Multimedia Gate Control may be layered on top of an Annex B/J.112 CMTS foundation, with the option of adding additional, complementary functionality as business indicates. Further, it should be emphasized that it is a significant asset of the IPCablecom architecture that both telephony and Multimedia variants employ considerable architectural similarity, leading to potential reuse in the underlying Gate management models.
+
+The IPCablecom Multimedia CMTS is a generalized version of the IPCablecom-T CMTS that has been defined in order to deliver telephony services in IPCablecom-T networks. The CMTS is responsible for fulfilling requests for QoS that are received from one or more Policy Servers. It performs this function by installing Gates, which are similar to the Gates defined in [9]; Gates allow the subscriber's cable modem to request network resources from the CMTS through the creation of dynamic DOCSIS flows with guaranteed levels of QoS. The CMTS also sends Event Messages detailing actual usage of QoS resources to the Record Keeping Server.
+
+#### 5.2.2.4 Record Keeping Server (RKS)
+
+The IPCablecom Multimedia Record Keeping Server fulfils a similar role to the RKS in IPCablecom-T [10]. It receives Event Messages pertaining to policy decisions from the Policy Server and Event Messages pertaining to QoS resource usage from the CMTS.
+
+In the IPCablecom Multimedia architecture, the Record Keeping Server does not receive messages directly from the Application Manager. However, the Application Manager can embed opaque data in messages that it sends to the Policy Server, and these data can then be included in Event Messages that are subsequently sent to the RKS.
+
+### 5.2.3 IPCablecom multimedia interfaces
+
+IPCablecom Multimedia builds on the IPCablecom-T suite of Recommendations. Where an IPCablecom Multimedia interface has a corollary in IPCablecom-T, IPCablecom Multimedia uses the same protocol, or an extension of the same protocol.
+
+![Diagram of IPCablecom multimedia architectural framework showing components and interfaces.](898fb89a50d9ec1dfb4e425c816976a7_img.jpg)
+
+The diagram illustrates the IPCablecom multimedia architectural framework. It features several components and their interconnections:
+
+- Client**: The primary user device, connected to a Cable modem and having direct connections to the Application manager (mm-7), CMTS (pkt-mm-6), Policy server (mm-9), and the Cable operator-managed IP network (mm-10).
+- Cable modem**: Positioned between the Client and the CMTS, connected via the pkt-mm-1 interface.
+- CMTS (Cable Modem Termination System)**: The central hub for the client's data, connected to the Cable modem (pkt-mm-1), Policy server (pkt-mm-2), Record keeping server (pkt-mm-5), and the Cable operator-managed IP network (mm-9).
+- Policy server**: Responsible for policy decisions, connected to the CMTS (pkt-mm-2), Record keeping server (pkt-mm-4), Application manager (pkt-mm-3), and the Cable operator-managed IP network (mm-9).
+- Record keeping server**: Stores records of events, connected to the CMTS (pkt-mm-5), Policy server (pkt-mm-4), and the Application manager (pkt-mm-3).
+- Application manager**: The central management component, connected to the Client (mm-7), Policy server (pkt-mm-3), Record keeping server (pkt-mm-3), and the Cable operator-managed IP network (mm-8).
+- Cable operator-managed IP network**: Represented by a cloud, it connects to the Client (mm-10), CMTS (mm-9), Policy server (mm-9), and the Application manager (mm-8).
+
+Interfaces are labeled as follows:
+
+- mm-7: Client to Application manager
+- pkt-mm-1: Cable modem to CMTS
+- pkt-mm-2: CMTS to Policy server
+- pkt-mm-3: Application manager to Policy server and Record keeping server
+- pkt-mm-4: Policy server to Record keeping server
+- pkt-mm-5: CMTS to Record keeping server
+- pkt-mm-6: Client to CMTS
+- mm-8: Application manager to Cable operator-managed IP network
+- mm-9: Client to Policy server and CMTS to Cable operator-managed IP network
+- mm-10: Client to Cable operator-managed IP network
+
+J.179\_F02
+
+Diagram of IPCablecom multimedia architectural framework showing components and interfaces.
+
+Figure 2/J.179 – IPCablecom multimedia architectural framework
+
+**Table 1/J.179 – IPCablecom multimedia interfaces**
+
+| Interface | Description                              | Notes                                                                                                                                                                                                                                                                                                                                                                                                  |
+|-----------|------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| pkt-mm-1  | CMTS – CM                                | The Cable Modem (CM) may request QoS from the CMTS via Annex B/J.112 DSx signalling. Alternatively, the CMTS may instruct the CM to set up, tear down or change a DOCSIS service flow in order to satisfy a QoS request, again via DSx signalling.                                                                                                                                                     |
+| pkt-mm-2  | PS – CMTS                                | This interface is fundamental to the policy-management framework. It controls policy decisions, which may be:<br>a) pushed by the Policy Server (PS) onto the CMTS; or<br>b) pulled from the PS by the CMTS.<br>The interface also allows for proxied QoS requests on behalf of a client. In some scenarios, this interface may also be used to inform the PS when QoS resources have become inactive. |
+| pkt-mm-3  | AM – PS                                  | The Application Manager (AM) may request that the PS install a policy decision on the CMTS on behalf of the client.<br>This interface may also be used to inform the AM of changes in the status of QoS resources.                                                                                                                                                                                     |
+| pkt-mm-4  | PS – RKS                                 | The PS sends event messages to the Record Keeping Server (RKS) to track policy decisions related to QoS.                                                                                                                                                                                                                                                                                               |
+| pkt-mm-5  | CMTS – RKS                               | The CMTS sends the RKS event messages to track requests for and usage of QoS (e.g., service flow additions, changes, deletions, and volume metrics).                                                                                                                                                                                                                                                   |
+| pkt-mm-6  | Client – CMTS                            | The client may use this interface to directly request and manage QoS network resources. If authorized, these resources are provided by the CMTS.                                                                                                                                                                                                                                                       |
+| mm-7      | Client – AM                              | This interface may be used by the client to interact with the AM and to request and manage QoS resources indirectly. This interface is out of the scope of this version of this Recommendation.                                                                                                                                                                                                        |
+| mm-8      | AM – Peer                                | The AM may use this interface to interact with some other entity that is part of the application in question. This interface is out of the scope of this version of this Recommendation.                                                                                                                                                                                                               |
+| mm-9      | CMTS – cable operator-Managed IP Network | This interface on the CMTS may be used in support of end-to-end QoS requests beyond the access network. This interface is out of the scope of this version of this Recommendation.                                                                                                                                                                                                                     |
+| mm-10     | Client – Peer                            | The Client may use this interface to interact with some other entity that is part of the application in question. This interface is out of the scope of this version of this Recommendation.                                                                                                                                                                                                           |
+
+#### 5.2.3.1 Client and application manager interface (mm-7)
+
+The interface between the client and the Application Manager is out of the scope of this Recommendation. Typically, the Application Manager will, through some means beyond the scope of this Recommendation, authenticate the client and ensure that the client is entitled to the Multimedia service. For example, the client may login to a web page and request service by providing a username and password. However it is accomplished, the Application Manager must be able to identify unambiguously the cable modem(s) to which service is to be delivered, since this information must be made available to the network operator before QoS can be delivered.
+
+#### **5.2.3.2 Application manager and policy server interface (pkt-mm-3)**
+
+This interface corresponds to the IPCablecom-T interface between a Call Agent and a Gate Controller. In IPCablecom-T this is a hidden, non-testable interface, and so there are no pre-existing protocol requirements on this interface.
+
+IPCablecom Multimedia requires the use of COPS [7] on this interface. In order to simplify the architecture and to allow for multiple levels of Policy Server elements between the Application Manager and CMTS, this interface mirrors as far as possible the interface between the Policy Server and the CMTS. Although the Application Manager is the one requesting resource authorization from the Policy Server, it actually issues this request in a COPS Decision message, instead of a COPS Request message. This allows the interface between the Application Manager and the Policy Server to appear identical to the interface between the Policy Server and the CMTS. The Application Manager is the PDP relative to the Policy Server, and the Policy Server is the PEP relative to the Application Manager.
+
+When an Application Manager agrees to provide service to a client, it sends a COPS Decision that contains (at least) the following information in the form of COPS objects:
+
+- Identity of the Application Manager making the request;
+- Identity of the client(s) to whom service is to be provided;
+- RSVP FlowSpec(s) specifying traffic envelope(s) for the session.
+
+In the reply from the Policy Server, the server includes an authorization token, the Gate-ID, which is provided to it by the CMTS.
+
+#### **5.2.3.3 Policy server and CMTS interface (pkt-mm-2)**
+
+This interface is essentially identical to the equivalent interface (between CMTS and Gate Controller) in IPCablecom-T. As in IPCablecom-T, COPS is used to transfer policy information between the Policy Server and the CMTS. The CMTS acts as a COPS PEP and the Policy Server acts as a COPS PDP. Following the IPCablecom-T model, the Policy Server initiates communication for a Multimedia session by sending a DQoS Gate-Set message (which is an unsolicited COPS DECISION message) to the CMTS.
+
+This message contains (at least):
+
+- Application Manager ID;
+- Subscriber ID;
+- GateSpec;
+- FlowSpec(s);
+- Classifier.
+
+The CMTS responds, as in DQoS, with either Gate-Set-Ack or Gate-Set-Err (both of which are COPS REPORT messages).
+
+If the CMTS responds positively (i.e., with a Gate-Set-Ack), it includes a GateID. As in IPCablecom-T, the GateID acts as an authorization token. Unlike IPCablecom-T, the token is not ultimately passed to the client (since Client Type 1 endpoints have no knowledge of IPCablecom); instead it is held by the Policy Server (if stateful) and by the Application Manager, thus allowing them to issue commands pertaining to this session of the CMTS, either directly in the case of the Policy Server, or indirectly via the Policy Server in the case of the Application Manager.
+
+#### **5.2.3.4 Record keeping server and policy server interface (pkt-mm-4) and record keeping server and CMTS interface (pkt-mm-5)**
+
+The interfaces into the Record Keeping Server from the Policy Server and the CMTS are identical to the equivalent interfaces (from CMS and CMTS, respectively) in IPCablecom-T (see [10]).
+
+These interfaces are used to carry IPCablecom Event Messages, which use RADIUS formatting. In IPCablecom Multimedia, Event Messages carry detailed information pertaining to the service delivered, including the exact time that service flows are created and deleted and (optionally) the amount of traffic that passed over the service flow while it was in existence.
+
+### **5.2.4 State information**
+
+In this clause, we provide an overview of state location in an IPCablecom Multimedia system. In addition to maintaining detailed state information, devices send information about state transitions to the Record Keeping Server for purposes such as billing, fraud detection, session reconstruction, etc.
+
+#### **5.2.4.1 Application state**
+
+The Application Manager is at all times responsible for maintaining detailed knowledge of the state of the application media session. How it does so in detail is beyond the scope of this Recommendation, but it is important to recognize that no devices other than the Application Manager are required or expected to maintain any knowledge of the application state.
+
+The Application Manager may, however, report session state by proxying such information via the Policy Server to the Record Keeping Server. In addition, some coarse state information (such as the fact that resources have been requested) is automatically sent from the Policy Server to the Record Keeping Server.
+
+#### **5.2.4.2 QoS resource state**
+
+The CMTS naturally is aware of the detailed state of flows that it manages. The Policy Server (if it is a stateful Policy Server) may also maintain a notion of the state of QoS resources on a single CMTS; it may also collate the state information over several CMTSs so that it (and only it) knows the QoS state of the entire system. This may be important, for example, if an operator has instituted a policy whereby a particular application is not to be permitted to consume more than a specified percentage of the total system resources. In a network with only stateless Policy Servers, the CMTSs are the only devices to maintain QoS state information. Since stateless Policy Servers do not maintain GateIDs, they cannot even interrogate a CMTS to obtain information about a particular Multimedia session.
+
+Whenever a QoS Resource transitions from one state to another, and whenever a QoS Resource is deleted, a corresponding Event Message is sent from the CMTS to the Record Keeping Server.
+
+# **6 Authorization interface description**
+
+This clause describes the interface between the Application Manager and the Policy Server, and the interface between the Policy Server(s) and the CMTS.
+
+The interface between the Application Manager and the Policy Server is translationally symmetric to the interface between the Policy Server and the CMTS. The interfaces are used to pass authorization, reservation and activation information to the CMTS, to provide state information from the CMTS to the Policy Server, and from the Policy Server to the Application Manager.
+
+The Application Manager is the PDP for the Service Control Domain. The Policy Server is the PEP with respect to the Application Manager and applies Resource Control Domain policies. The Policy Server is a PDP with respect to the CMTS, and the CMTS is the PEP with respect to the Policy Server and lies in the actual packet forwarding path.
+
+This clause describes the use of the COPS protocol to transport IPCablecom QoS messages between the Application Manager and Policy Server, and between the Policy Server and CMTS.
+
+## 6.1 Gates: The framework for QoS control
+
+An IPCablecom Multimedia Gate is a logical representation of a policy decision that has been installed on the CMTS. A Gate is used to control access by a single IP flow to enhanced QoS Services provided by an Annex B/J.112 cable network. Gates are unidirectional; a single Gate controls access to a flow in either the upstream or the downstream direction, but not both. For a bidirectional IP session, two Gates are required, one for upstream and one for downstream, each identified by a unique GateID. It is important to recognize that this is a fundamental difference from IPCablecom-T, in which a single GateID may reference both an upstream and a downstream Gate.
+
+In IPCablecom Multimedia, each Gate has a separate GateID. The Gate defines the authorization, reservation and committed envelopes to be used by the CMTS to perform authorization, reservation and commit operations.
+
+In all Scenarios, the CMTS MUST perform admission control checks of the envelopes to make sure that the committed envelope is less than or equal to the reserved envelope, and the reserved envelope is less than or equal to the authorized envelope. (See [1] for specific DOCSIS admission control requirements.)
+
+In the 'Proxied QoS Policy Push' (Scenario 1) model, the information in a Gate is used by the CMTS to create the Annex B/J.112 Service Flow directly, after the CMTS performs the necessary admission control checks of the envelopes. In the other two models outlined in Appendix I, 'Client requested QoS with Policy Push' (Scenario 2) and 'Client requested QoS Policy Pull' (Scenario 3), the CMTS uses the Gate information to perform admission control of the client requested resources; the CMTS does not initiate creation of the flows. The Application Manager is responsible for issuing Gate messages to the Policy Server and the Policy Server is responsible for applying policy rules, and then issuing Gate Control messages to the CMTS.
+
+A Gate consists of the following elements, which are described later in this clause:
+
+- GateID;
+- AMID;
+- SubscriberID;
+- GateSpec;
+- Classifier;
+- Traffic Profile;
+- Event Generation Info (optional);
+- Time-Based Usage Limit (optional);
+- Volume-Based Usage Limit (optional);
+- Opaque Data (optional).
+
+GateID is the handle for the Gate. The GateID is assigned by the CMTS and is used by the Application Manager, Policy Server and client to reference the Gate.
+
+AMID is the handle that identifies the Application Manager.
+
+SubscriberID uniquely identifies the Client for which the policy is being set.
+
+GateSpec describes specific authorization parameters defining a Gate (i.e., QoS limits, timers, etc.)
+
+Classifier describes the IP flow(s) that will be mapped to the DOCSIS Service Flow.
+
+Traffic Profile describes the QoS attributes of the Service Flow used to support the IP flow.
+
+Event Generation Information contains information used by the CMTS for the purpose of accounting and usage reporting.
+
+Volume-Based Usage Limit defines a volume cap for traffic traversing the flow associated with the Gate.
+
+Time-Based Usage Limit describes a time cap limiting the duration of the flow associated with the Gate.
+
+Opaque Data represents a general-purpose object that remains opaque to the CMTS and PS elements, but which may contain data that is significant to the AM. This optional object, if provided by the AM, is retained at the CMTS and returned in all associated responses (see 6.4.2.11).
+
+These elements are communicated to the Policy Server and the CMTS via COPS objects and are described in greater detail later in this clause. During the installation of the Gate, the information above is communicated to the CMTS. After the installation is complete, a DOCSIS Service Flow can be created. After the creation of the DOCSIS Service Flow, the Gate has associated with it an additional element, the DOCSIS Service Flow. There is a strict one-to-one mapping between a DOCSIS Service Flow and a Gate.
+
+A Gate transitions through multiple states. In Scenarios 2 and 3, where the client entity is responsible for reserving and then activating the DOCSIS Service Flows, a Multimedia Gate behaves in a manner very similar to an IPCablecom-T DQoS Gate. When the Policy Server installs the Gate onto the CMTS, the Gate is said to be in an 'Authorized' state. It remains in this state until explicitly deleted by the Policy Server (or, less likely, it is deleted for some reason by the CMTS itself), or until a dynamic flow request from the client arrives.
+
+When the client requests that a dynamic Service Flow be added, it presents the GateID as an authorization token. The CMTS uses the GateID to perform admission control on the DOCSIS dynamic flow against the authorized envelope defined by the Gate. In Scenario 1, the Policy Server instructs the CMTS to transition between the states on behalf of the Application Manager, and the CMTS is the entity responsible for initiating and tearing down DOCSIS Service Flows. The State Transition clause in this Recommendation describes this behaviour. When the CMTS is instructed to tear down a DOCSIS Service Flow, its associated Gate remains until explicitly deleted by the PS/AM or until it times out and its resources are reclaimed by the CMTS (see 6.5.8). In contrast, however, when the PS/AM deletes a Gate, the CMTS will delete the associated DOCSIS Service Flow.
+
+### 6.1.1 Gate identification (GateID)
+
+A GateID is an identifier that is locally allocated by the CMTS where the Gate resides. A GateID MUST be associated with only one Gate. Whereas the IPCablecom-T DQoS Gate Control model generally assumed a pair of unidirectional Gates (one upstream and one downstream) per GateID in support of a typical two-way voice session, here the Gate/GateID relationship is explicitly one-to-one, so that it is easier to support a wide range of Multimedia services.
+
+When the Application Manager issues a Gate-Set request, this triggers the Policy Server to issue a Gate-Set message to the CMTS. When the CMTS responds with an acknowledgment containing the GateID, the Policy Server forwards this response including the GateID back to the Application Manager. Note that since there can be a many-to-many relationship between a PS and CMTS, the GateID assigned by one CMTS cannot be guaranteed to be unique across the network, so the PSs may use the AMID of the AM along with the SubscriberID and GateID in order to uniquely identify the Gate.
+
+An algorithm that may be used to assign values of GateIDs is as follows. Partition the 32-bit word into two parts, an index part, and a random part. The index part identifies the Gate by indexing into a small table, while the random part provides some level of obscurity to the value. Regardless of the algorithm chosen, the CMTS SHOULD attempt to minimize the possibility of GateID ambiguities by ensuring that no GateID gets reused within three minutes of its prior closure or deletion. For the
+
+algorithm suggested, this could be accomplished by simply incrementing the index part for each consecutively assigned GateID, wrapping around to zero when the maximum integer value of the index part is reached.
+
+### 6.1.2 Application manager identification (AMID)
+
+Each Application Manager is pre-provisioned with an AMID that is unique within the universe of a single service provider; the Application Manager includes this identifier in all messages that it issues to the Policy Server. The Policy Server transparently passes this information to the CMTS via Gate Control messages. The CMTS MUST return the AMID associated with the Gate to the Policy Server. The Policy Server uses this information to associate Gate messages with a particular Application Manager.
+
+The AMID MUST be a globally unique value assigned to the Application Manager by the service provider. The Application Manager MUST use the assigned AMID in all its interactions with Policy Servers. Note that since the Application Manager may be operated by a third party, and a single Application Manager could interact with multiple service provider operators, a single physical Application Manager may be provisioned with multiple AMIDs.
+
+### 6.1.3 Subscriber identification (SubscriberID)
+
+The SubscriberID, consisting of the IP address of either the client CPE device or CM, identifies the user requesting the service. In complex network environments, this address may be used to route Gate Control messages between a number of Policy Servers and to determine which CMTS is providing service to a particular endpoint. In addition to the IP address, a subscriber may also be identified via a FQDN or some opaque data (object defined below) relevant to the service in question.
+
+### 6.1.4 Gate specification (GateSpec)
+
+The GateSpec describes some high level attributes of the Gate, and contains information regarding the treatment of other objects specified in the Gate message. Information contained in a GateSpec is outlined below:
+
+- GateID;
+- SessionClassID;
+- Direction;
+- Authorized Timer;
+- Reserved Timer;
+- Committed Timer;
+- Committed Recovery Timer;
+- DSCP/TOS Override.
+
+GateID uniquely identifies the Gate for which the operation should be performed.
+
+SessionClassID provides a way for the Application Manager and the Policy Server to group Gates into different classes with different authorization characteristics. For example, one could use the SessionClassID to represent some prioritization or preemption scheme that would allow either the Policy Server or the CMTS to preempt a pre-authorized Gate in favor of allowing a new Gate with a higher priority to be authorized.
+
+Direction indicates whether the Gate is for an upstream or downstream flow. Depending on this direction, the CMTS MUST reserve and activate the DOCSIS flows accordingly.
+
+Authorized Timer limits the amount of time the authorization must remain valid before it is reserved (see 6.2).
+
+Reserved Timer limits the amount of time the reservation must remain valid before the resources are committed (see 6.2).
+
+Committed Timer limits the amount of time a committed service flow may remain idle.
+
+Committed Recovery Timer limits the amount of time that a committed service flow can remain without a subsequent refresh message from the PS/AM once the PS/AM has been notified of inactivity (see 6.2).
+
+DSCP/TOS Override field can be used to override the DSCP/TOS field of packets associated with the DOCSIS Service Flow that corresponds to the Gate. This field MAY be unspecified in which case the DSCP/TOS field in the packet is not over-written by the CMTS. This field MAY be used in both the upstream and downstream directions.
+
+### 6.1.5 Classifier
+
+A Classifier MUST be defined for a Gate. Additional Classifiers may be included in the original Gate-Set. Classifiers may be added or deleted in a subsequent Gate-Set. Compliant implementations MUST be able to support a minimum of four Classifiers when processing a Gate-Set message. The Classifier identifies the IP flow that will be mapped to the DOCSIS service flow associated with the Gate. The Classifier used to construct a Service Flow MUST match the Classifier specified for the Gate. In Scenario 1, when the CMTS creates the dynamic flow, it MUST use the Gate Classifier as the Classifier for the DOCSIS Service Flow.
+
+A classifier is an eight-tuple:
+
+- Protocol;
+- Source IP;
+- Source Port;
+- Destination IP;
+- Destination Port;
+- Priority;
+- DSCP/TOS Mask.
+
+Protocol field identifies the type of protocol (e.g., IP, ICMP, etc).
+
+Source IP is the IP address (as seen at the CMTS) of the originator of the IP flow, while Destination IP is the termination point for the IP flow.
+
+Source Port and Destination Port specify the UDP or TCP ports for the IP flow.
+
+Priority may be used to distinguish between multiple Classifiers which match a particular packet. This is typically set to a default value since Classifiers are generally intended to be unique.
+
+DSCP/TOS field identifies the DSCP/TOS field that must be matched for packets to be classified onto the IP flow. To provide for maximum flexibility in defining a network management strategy, an accompanying mask is defined which determines which bits in the DSCP/TOS byte are to be used as filters in classifying packets. This allows for both DiffServ and TOS strategies (which each define and use separate bits within this byte).
+
+A Classifier MAY have wild-carded fields (indicated by zeroed fields), but care must be taken so that multiple IP flows do not unintentionally match the same Classifier, which can lead to unexpected results.
+
+### 6.1.6 Traffic profile
+
+There are three basic ways to express the Traffic Profile for a Gate:
+
+- 1) FlowSpec;
+- 2) DOCSIS Service Class Name; or
+- 3) DOCSIS-Specific Parameterization.
+
+The Policy Server or Application Manager MUST define the Traffic Profile for a Gate using one of the following:
+
+- 1) the FlowSpec;
+- 2) DOCSIS Service Class Names; or
+- 3) DOCSIS-Specific Parameters.
+
+All envelopes used in a Traffic Profile MUST be the same type, i.e., either FlowSpec, DOCSIS Service Class Names, or DOCSIS-Specific Parameters.
+
+There MUST be at least one set of Traffic Profile parameters specified when the Gate is first being installed. The Policy Server and Application Manager MAY specify a second set to represent the reserved envelope, and a third set to represent the committed envelope. If the CMTS is told to immediately create a dynamic flow upon receipt of a Gate-Set message (via the presence of the reserved or committed envelopes), the CMTS MUST use the reserved and committed envelope Traffic Profile parameters to perform the Annex B/J.112 messaging to create the flow, in the direction specified by the Direction field in the GateSpec (provided the request is authorized and sufficient resources exist to satisfy the request). When told to transition into the Committed state, the CMTS MUST use the Traffic Profile to activate the DOCSIS Service Flow. As an optimization, the Policy Server MAY tell the CMTS to perform all three actions (authorize, reserve and commit) on behalf of the Application Manager via a single Gate Control message. Alternatively, the PS/AM MAY issue separate Gate-Set messages to tell the CMTS to authorize and reserve and then to commit via a subsequent Gate-Set message.
+
+#### 6.1.6.1 FlowSpec
+
+The FlowSpec object contains RSVP FlowSpecs that are used to describe the Traffic Profile of the IP flow. The FlowSpec object can contain multiple RSVP FlowSpecs:
+
+- FlowSpec that defines the authorization resource envelope against which future reservations can be made.
+- FlowSpec that defines the reserved envelope against which future commit requests can be made.
+- FlowSpec that defines the resources to be committed.
+
+RSVP FlowSpecs support two types of services: controlled load [4] and guaranteed [5]. The main difference between the two types of services is discussed in clause 8. The two types of services are distinguished based on the FlowSpec Service number, which is specified in the RSVP FlowSpec. Service number 5 is for controlled load, and Service number 2 is for guaranteed. A controlled load service MUST contain only the TSpec token bucket parameters, and not the RSpec. A guaranteed service MUST contain both the TSpec and the RSpec.
+
+Please refer to clause 8 for information on how to explicitly map RSVP parameters into DOCSIS parameters. When deriving the DOCSIS parameters using the RSVP FlowSpec parameters, there are some DOCSIS parameters that are highly approximated. If the approximations do not give the Policy Server or Application Manager the control it desires, the PS/AM MAY use the other methods of defining the Traffic Profile, which includes the ability to define some DOCSIS-specific parameters. These parameters allow the Policy Server or Application Manager to fine-tune the standard mapping of FlowSpecs to DOCSIS parameters.
+
+#### **6.1.6.2 DOCSIS service class name**
+
+The DOCSIS Service Class Name indicates the DOCSIS Service Class to be used to describe the QoS attributes. A CMTS MUST support DOCSIS Service Class Names.
+
+DOCSIS Service Class Name enables one to use pre-provisioned DOCSIS QoS parameters on the CMTS. On the CMTS, one can configure DOCSIS Named Service Classes with different DOCSIS QoS profiles, then reference the DOCSIS Service Class Name in the Gate to indirectly associate a QoS profile with a particular Gate. DOCSIS also allows the parameters to be modified through the use of TLVs. Within IPCablecom Multimedia, DOCSIS Service Class Name QoS parameters MUST NOT be modified through the use of TLVs. A CMTS MUST return error "Undefined Service Class Name" if modifications to the Service Class Name QoS parameters are requested (see 6.4.2.14).
+
+For more information on DOCSIS Service Classes please refer to B.10.1.3/J.112 [1].
+
+#### **6.1.6.3 DOCSIS specific parameterization**
+
+The third way of defining the Traffic Profile consists of using DOCSIS-specific Traffic Profile; this allows the Application Manager to explicitly specify the DOCSIS parameters of the DOCSIS flow. If the Application Manager wishes to use this third way of defining a Traffic Profile, it MUST include an object containing the DOCSIS Specific Parameters.
+
+All DOCSIS Service Flow Scheduling types are supported via several different Traffic Profile S-Types. Each S-Type has a different encoding of the DOCSIS-specific parameters relevant to that Service Flow Scheduling type. For further details regarding DOCSIS-specific parameterization refer to 6.4.2.7.
+
+### **6.1.7 Event generation info**
+
+This object contains information relevant to the CMTS in support of accounting and billing functions. Attributes include:
+
+- Primary Address: Port of the Primary Record Keeping Server to which the CMTS MUST send event records.
+- Secondary Address: Port of the Secondary Record Keeping Server, the CMTS MUST use as specified in [10] if the primary is unavailable.
+- Flag indicating whether the CMTS MUST send Event Messages to the Record Keeping Server in real-time, or whether the CMTS MUST batch Event Messages and send them at periodic intervals.
+- BillingCorrelationID, which the CMTS MUST pass to the Record Keeping Server with each event record.
+
+Omission of the Event Generation Info object indicates that the CMTS MUST NOT generate Event Messages for a specific Gate.
+
+### **6.1.8 Time-based usage limit**
+
+This object specifies amount of time a Gate can remain committed before meeting the time-limit threshold for this Gate. This object is opaque to the CMTS. The CMTS is not responsible for enforcing time-limits, but MUST store this object and return it upon request.
+
+### **6.1.9 Volume-based usage limit**
+
+The Application Manager uses the Volume-Based Usage Limit to signal the CMTS to generate a Gate Control message when the specified amount of data has traversed the Gate. The CMTS is not responsible for enforcing volume limits, but MUST signal to the PS/AM when a volume limit is reached.
+
+### **6.1.10 Opaque data**
+
+Opaque Data consists of general information that a Policy Server or Application Manager can store on a CMTS. This data remains opaque to the CMTS, but contains information useful for the PS or AM. If provided by the PS/AM, the CMTS will return this object in all responses (see 6.4.2.11).
+
+### **6.1.11 Gate time info**
+
+Gate Time Info contains a timestamp representing the time the Gate was committed. This may be queried and used by a Policy Server or Application Manager to enforce time-based network policy.
+
+### **6.1.12 Gate usage info**
+
+Gate Usage Info consists of an octet counter indicating the number of bytes of data transmitted over this Gate (see 6.4.2.13). Analogous to the Gate Time Info object, this information may be used by a Policy Server or Application Manager to enforce volume-based network policy.
+
+## **6.2 Gate transitions**
+
+As briefly outlined earlier, a Gate may reside in the following logical states:
+
+- Authorized – a Policy Server has authorized the flow with resource limits defined;
+- Reserved – resources have been reserved for the flow;
+- Committed – resources are active and are being used;
+- Committed-Recovery – inactivity has been detected on the flow; resource recovery pending.
+
+For the state machine depicted in Figure 3, the CMTS MUST complete the triggering event with a successful outcome before it transitions a gate from one state to another. For Gate Control events, the CMTS MUST not change state until the request has been fully processed (including any resulting flow transitions) and the CMTS has determined that a success acknowledgement is to be transmitted.
+
+![State transition diagram for Gate states: Start, Authorized, Reserved, Committed, and End. Transitions are triggered by Gate-Set messages (Authorize, Reserve, Commit, Delete) and timer expiries (T1, T2, T3).](11edb7fcedf09ac6a817f8d7b8c61eec_img.jpg)
+
+```
+
+stateDiagram-v2
+    [*] --> Authorized : Gate-Set: Authorize/ Start timer T1
+    Authorized --> Authorized : Gate-Set: Authorize/ (Mid-session change), Reset T1
+    Authorized --> End : Gate-Delete/ Stop timer T1, Send Gate-Delete-Ack
+    Authorized --> End : T1 timer expiry/ Send Gate-Report-State
+    Authorized --> Reserved : Gate-Set: Reserve/ Stop timer T1, Start timer T2
+    Reserved --> Authorized : Gate-Set: Authorize/ Stop timer T2, Start timer T1
+    Reserved --> Reserved : Gate-Set: Reserve/ (Mid-session change), Reset T2
+    Reserved --> End : Gate-Delete/ Stop timer T2, Send Gate-Delete-Ack
+    Reserved --> End : T2 timer expiry/ Send Gate-Report-State
+    Reserved --> End : Flow release/ Stop timer T2, Send Gate-Report-State
+    Reserved --> Committed : Gate-Set: Commit/ Stop timer T2, Start timer T3
+    Committed --> Authorized : T3 timer expiry/ Send Gate-Report-State, Reset T1
+    Committed --> Reserved : Gate-Set: Reserve/ Stop timer T3, Start timer T2
+    Committed --> End : Flow Release/ Stop timer T3, Send Gate-Report-State
+    Committed --> End : Gate-Delete/ Stop timer T3, Send Gate-Delete-Ack
+    Committed --> Committed : Gate-Set: Commit/ (Mid-session change) or Service Flow Activity, Reset T3
+  
+```
+
+State transition diagram for Gate states: Start, Authorized, Reserved, Committed, and End. Transitions are triggered by Gate-Set messages (Authorize, Reserve, Commit, Delete) and timer expiries (T1, T2, T3).
+
+**Figure 3/J.179 – Gate state transitions**
+
+The CMTS MUST support Gate states and transitions as shown in Figure 3 and described in this clause. The CMTS MUST also implement transitions for protocol error processing.
+
+In this clause we describe the state transitions of the Gate in the CMTS that result from external events (Gate Control messages from the Policy Server), as well as transitions that result from internal events (e.g., timer expiration). Note that the Policy Server is not the source of the external events; instead the Policy Server is merely acting as a proxy for the Application Manager, which is the trigger for the events.
+
+### 6.2.1 Authorized
+
+A Gate is created in the CMTS by a Gate-Set command from the Policy Server. The CMTS allocates a unique identifier called a GateID. The Gate is now said to be in the Authorized state and the CMTS MUST start Timer T1. Timer T1 limits the amount of time the authorization remains valid.
+
+A Gate in the Authorized state MUST be deleted upon receipt of a Gate-Delete message. When this happens, the CMTS MUST respond with a Gate-Delete-Ack message and MUST stop Timer T1.
+
+The CMTS is REQUIRED to support the following state transitions while a Gate is in the Authorized state:
+
+Authorized State Transitions:
+
+- Authorized Loopback to Authorized: Modify Authorized Envelope;
+- Authorized to Reserved (defines Reserved Envelope  $\leq$  Authorized Envelope);
+- Authorized to End (deletes Authorized Envelope).
+
+The CMTS MUST NOT support any other state transitions for a Gate in the Authorized state, but a number of separate stimuli may result in the transitions described.
+
+When the Gate is installed, it is said to be in an Authorized State. While in the Authorized state, the Policy Server MAY modify any of the parameters associated with a Gate (e.g., Traffic Profile, Classifier, etc). If in an Authorized state a Gate-Set message is received which does not transition the Gate to the Reserved or Committed states, then the CMTS MUST restart timer T1.
+
+While in the Authorized state, the CMTS MUST transition the Gate into the Reserved state upon successful request of the Policy Server. The CMTS MUST transition the Gate into the End state upon receipt of a Gate-Delete from the Policy Server or upon T1 timer expiration.
+
+### 6.2.2 Reserved
+
+A Gate in the Authorized state is expecting the client to attempt to reserve resources. In Scenario 1, the Policy Server reserves the resources on the client's behalf. To reserve resources, the Policy Server MUST issue a subsequent Gate-Set message with a Traffic Profile that includes the Reserved Envelope. On receipt of this reserve request, the CMTS MUST verify the request is within the authorization limits established for the Gate and perform admission control procedures.
+
+If the Reserve request does not arrive before Timer T1 expires, the CMTS MUST delete the Gate, and notify the Policy Server of the state change. If admission control succeeds and only resource reservation was requested, the CMTS MUST put the Gate in the Reserved state. Simultaneously, the CMTS MUST also stop timer T1 and start timer T2 (Reserved Timer). If admission control procedures are not successful, the CMTS MUST maintain the Gate in the Authorized state and provide a Gate-Set-Err response to the PS.
+
+The CMTS is REQUIRED to support the following state transitions while a Gate is in the Reserved state:
+
+Reserved State Transitions:
+
+- Reserved Loopback to Reserved: Modify Authorized Envelope ( $\geq$  Reserved Envelope);
+- Reserved Loopback to Reserved: Modify Reserved Envelope ( $\leq$  Authorized Envelope);
+- Reserved to Committed (defines Committed Envelope  $\leq$  Reserved Envelope);
+- Reserved to End (deletes Reserved and Authorized Envelopes).
+
+The CMTS MUST NOT support any other state transitions for a Gate in the Reserved state, but a number of separate stimuli may result in the transitions described.
+
+From the Authorized state, the CMTS MUST transition the Gate into the Reserved state, if requested by the Policy Server as long as the Reserved envelope is less than or equal to the Authorized envelope, the request passes admission control, and the flow is successfully reserved. Once in the Reserved state, the Gate's Authorized envelope MAY be modified via a Gate-Set message. The Gate's Reserved envelope can also be modified in the Reserved State (see 6.5.6). If in a Reserved state a Gate-Set message is received which does not transition the Gate to the Authorized or Committed states, then the CMTS MUST restart timer T2.
+
+If the Commit request does not arrive before timer T2 expires, the CMTS MUST delete the Gate, and notify the Policy Server of the state change.
+
+The Reserved envelope MUST always be less than or equal to the Authorized envelope. In the Reserved state, for a CMTS to transition a Gate to the Committed state, the Committed Envelope MUST be less than or equal to the Reserved Envelope (see 6.5.3).
+
+While in the Reserved state, the Policy Server may modify the Authorized envelope by specifying a new Traffic Profile in a Gate-Set message. The new Traffic Profile will define a modified Authorized envelope, and the same Reserved Envelope that was used previously to transition the Gate into the Reserved state. However, all requests to modify Authorized, Reserved or Committed envelopes MUST conform to the general rule:
+
+$$\text{Authorized Envelope} \geq \text{Reserved Envelope} \geq \text{Committed Envelope}$$
+
+The Policy Server MAY delete a Gate in the Reserved state by issuing a Gate-Delete message.
+
+### 6.2.3 Committed
+
+In the Reserved state the Gate is expecting the client to commit resources, and thereby activate them. In Scenario 1, the Policy Server commits the resources on the client's behalf. To commit resources, the Policy Server MUST issue a Gate-Set command with a Traffic Profile that includes the Committed Envelope. The CMTS MUST again authorize the requested QoS against the Reserved envelope. If the authorization succeeds, the CMTS MUST start timer T3, and either stop timer T2 if the Authorized envelope equals the Committed envelope, or restart timer T2 if the Authorized Envelope is greater than the Committed Envelope. If the authorization fails, the CMTS MUST reset timer T2.
+
+Note that once the DOCSIS Service Flow has been activated, the CMTS MUST refresh timer T3 when data is transferred over the flow. If there is no activity on the flow for time equal to T3, the CMTS MUST notify the Policy Server of the state change. Likewise, the Policy Server MUST notify the Application Manager of the state change.
+
+In the Committed state, the Application Manager MAY delete the Gate by issuing a Gate-Delete message to the Policy Server, which in turn MUST relay the message onto the CMTS. If the Policy Server issues a Gate-Delete message to the CMTS, the CMTS MUST delete the Gate and the corresponding Service Flow and stop timers T2 and T3 if they are running.
+
+The CMTS is REQUIRED to support the following state transitions while a Gate is in the Committed state:
+
+Committed State Transitions:
+
+- Committed Loopback to Committed: Modify Authorized Envelope ( $\geq$  Reserved Envelope);
+- Committed Loopback to Committed: Modify Reserved Envelope ( $\geq$  Committed Envelope) and  $\leq$  Authorized Envelope);
+- Committed Loopback to Committed: Modify Committed Envelope ( $\leq$  Reserved Envelope);
+- Committed to Reserved (deletes Committed Envelope);
+- Committed to Committed-Recovery: (initiate resource recovery process);
+- Committed to End (deletes Committed, Reserved and Authorized Envelopes).
+
+The CMTS MUST NOT support any other state transitions for a Gate in the Committed state, but a number of separate stimuli may result in the transitions described.
+
+While in the Reserved State, the CMTS MUST transition a Gate to the Committed state, if requested by the Policy Server as long as the Committed Envelope is less than or equal to the Reserved Envelope (see 6.5.3). While in the Committed state, the Policy Server MAY modify the Authorized Envelope of the Gate via a Gate-Set message, as long as the Authorized Envelope is greater than or equal to the Reserved Envelope. In this state, the Policy Server MAY also modify the Reserved envelope, as long as the reserved envelope is greater than or equal to the Committed Envelope. In this state, the Policy Server MAY even modify the Committed envelope, as long as the new envelope is less than or equal to the Reserved Envelope. If a request is received to de-commit all resources (but keep them reserved) while the Gate is in the Committed state, the CMTS MUST stop timer T3, (re-)start timer T2, and transition back to the Reserved state. In Scenario 1, the Policy Server MAY request this action by issuing a Gate-Set message with the a Traffic Profile that includes the Authorized and Reserved Envelopes, but does not include a Committed Envelope.
+
+While in the Committed state, the CMTS MUST transition a Gate to the End state upon receiving a Gate-Delete message from the Policy Server. While in the Committed state, the Policy Server MAY modify the Authorized or Reserved envelope by simply specifying the new Traffic Profile; the new Traffic Profile MUST contain modified Authorized or Reserved envelopes, and the same Committed Envelope that was used previously to transition the Gate into the Committed state.
+
+When (re-)entering the Committed state due to the receipt of a Gate-Set message, the CMTS MUST (re-)start timer T2 if the Reserved Envelope is greater than the Committed Envelope, or MUST stop timer T2 if it was previously running and the Reserved Envelope is now equal to the Committed Envelope.
+
+While in the Committed state:
+
+- 1) If the timer T2 expires the Gate MUST remain in the Committed state and the CMTS MUST send a Gate-Report-State with Reason code 9 (Gate state unchanged, but T2 timer expiration caused reservation reduction) to the Policy Server indicating the reduction in reserved resources;
+- 2) If a Gate-Set transitions the Gate back to the Reserved state the timer T2 MUST be started if it was not running and restarted if had previously been running; and
+- 3) If a transition to the End state occurs both the timer T2 and T3 MUST be stopped if they are running.
+
+As an optimization, for Scenario 1, the Policy Server MAY Authorize, Reserve and Commit at the same time by issuing a Gate-Set message with the Traffic Profile that includes all three envelopes set such that the CMTS is told to execute all three actions sequentially without any further interaction from the Policy Server: that is, they must all succeed (if so, the CMTS MUST indicate this by a Gate-Set-Ack) or fail (if so, the CMTS MUST indicate this by a Gate-Set-Err).
+
+From the Committed state, the Gate transition to the Committed Recovery state due to the expiration of the T3 timer. If the CMTS detects that there has been no activity on the associated flow for a duration of T3, the CMTS MUST start the T4 timer, generate a Gate-Report-State message to the Policy Server indicating that the flow has been inactive for time duration defined by T3 and transition to the Committed-Recovery state, while leaving the associated flow in the activated state. The Policy Server MUST relay the Gate-Report State message to the Application Manager. The Application Manager MUST either refresh the policy by issuing a Gate-Set message, or remove the Gate by issuing a Gate-Delete message.
+
+Certain applications may not wish to be notified when activity on the flow ceases. In this case, the Application Manager may set the T3 timer (which corresponds to the DOCSIS Active Timer) to 0. As specified in [1], a value of 0 for the DOCSIS Active Timer indicates that activity detection on
+
+the CMTS is turned off for that flow. Thus, the Gate will remain in the Committed state forever until either a Gate-Delete is received or the CM goes offline.
+
+### 6.2.4 Committed-recovery
+
+In the Committed state the flow associated with the Gate is active. If the CMTS detects that the flow is unused for a time in excess of the T3 timer, the CMTS notifies the PS (who notifies the AM) that the service-flow associated with the gate has been unused, starts the T4 timer and transitions the Gate to the Committed-Recovery state.
+
+NOTE – If the T2 timer is running it will continue running. It MUST NOT be reset.
+
+The AM must decide to either refresh the policy by issuing a Gate-Set message to the PS or delete the Gate by issuing a Gate-Delete message to the PS. The Policy Server MUST forward the Gate-Set message or Gate-Delete message to the CMTS.
+
+If, while in the Committed-Recovery state, the CMTS receives a Gate-Set message for the Gate before the timer T4 expires, then the CMTS MUST stop the T4 timer, restart the T3 timer, transition the Gate back to the Committed state and (re-)start the T2 timer if the Reserved Envelope is greater than the Committed Envelope or stop the T2 timer if it is running and the new Reserved Envelope is equal to the Committed Envelope.
+
+If, while in the Committed-Recovery state, the CMTS receives a Gate-Delete message before the timer T4 expires, then the CMTS MUST stop the T4 Timer, delete the Gate and the corresponding service flow, and stop the T2 timer if it is running.
+
+If the timer T4 expires while in the Committed-Recovery state, then the CMTS MUST send a Gate-Report-State message to the PS, stop the T2 timer if it is running, tear down the service flow associated with the Gate, and then delete the Gate. Likewise, the Policy Server MUST notify the Application Manager of the state change.
+
+If the timer T2 expires while in the Committed-Recovery state, then the Gate MUST remain in the Committed-Recovery state and the CMTS MUST send a Gate-Report-State with Reason code 9 (Gate state unchanged, but T2 timer expiration caused reservation reduction) to the Policy Server indicating the reduction in reserved resources.
+
+The CMTS MUST support the following state transitions while a Gate is in the Committed-Recovery state:
+
+Committed-Recovery State Transitions:
+
+- Committed-Recovery to Committed: (policy has been refreshed);
+- Committed-Recovery to End (deletes Committed, Reserved and Authorized Envelopes);
+- Committed-Recovery to Committed-Recovery (Timer T2 Expiry; send Gate-Report-State).
+
+The CMTS MUST NOT support any other state transitions for a Gate in the Committed-Recovery state, but a number of separate stimuli may result in the transitions described.
+
+There may be applications that do not wish to keep a Gate once inactivity has been detected. In this instance, the AM may set the T4 timer to 0. When T4 is set to zero, essentially no time is spent in the Committed-Recovery state and the Gate (and flow) MUST be deleted when the T3 timer expires.
+
+## 6.3 COPS profile for IPCablecom multimedia
+
+As defined earlier, admission control involves the process of managing QoS resource requests based on administrative policies and available resources. High-level operational modules associated with this process are depicted in Appendix I. Under this model, administrative policies are stored in a policy database and controlled by the Policy Server.
+
+![Diagram of QoS admission control layout showing the interaction between Application Manager, Policy Server, CMTS, and Network equipment.](dcc2d5a5b39f780e7a224bb01ba1ef6e_img.jpg)
+
+The diagram illustrates the QoS admission control layout. At the top, an 'Application state database' (oval) is connected to an 'Application Manager' (rectangle) labeled '(PDP wrt Police Server)'. Below this, a 'COPS interface via TCP/IP' (double-headed arrow) connects to a 'Policy Server' (rectangle) labeled '(PEP wrt Application Manager)' and '(PDP wrt CMTS)'. The 'Policy Server' is connected to a 'Policy database' (oval). Below the Policy Server, another 'COPS interface via TCP/IP' (double-headed arrow) connects to a 'CMTS' (rectangle) labeled '(PEP wrt Policy Server)'. The 'CMTS' is connected to 'Network equipment' (oval), which has an 'Ingress interface' on the left and an 'Egress interface' on the right. The label 'J.179\_F04' is in the bottom right corner.
+
+Diagram of QoS admission control layout showing the interaction between Application Manager, Policy Server, CMTS, and Network equipment.
+
+**Figure 4/J.179 – QoS admission control layout**
+
+Admission control decisions made by the Policy Server MUST be communicated to the CMTS or Application Manager using COPS. The CMTS MAY make QoS Admission Control requests to the COPS Server based on network events triggered by either the QoS signalling protocol, or via data flow detection mechanisms. The network event can also be in need of QoS bandwidth management, e.g., a new QoS capable interface becomes operational.
+
+QoS policy decisions made by the Policy Server MAY be pushed to the CMTS based on a request from the Application Manager. The CMTS MAY access that decision information to make policy enforcement decisions on incoming session requests received at the CMTS. The CMTS MUST NOT support CM-initiated DSx messages in IPCablecom Multimedia. The CMTS MUST treat a CM-initiated DSx message as a request with an invalid GateID.
+
+A COPS client/server configuration supporting QoS Admission Control is specified in the IETF's COPS protocol [7]. This protocol includes the following operations:
+
+- Client-Open (OPN)/Client-Accept (CAT)/Client-Close (CC). The COPS client (PEP) sends an OPN message to initiate a connection with the COPS server (PDP), and the server responds with a CAT message to accept the connection. The server or client sends a CC message to terminate the connection.
+- Request (REQ). The client sends a REQ message to the server to request admission control decision information or device configuration information. The REQ message may contain client-specific information that the server uses, together with data in the session admission policy database, to make policy-based decisions.
+- Decision (DEC). The server responds to REQs by sending a DEC back to the client that initiated the original request. DEC messages may be sent immediately in response to a REQ
+
+(i.e., a solicited DEC) or at any time after to change or update a previous decision (i.e., an unsolicited DEC).
+
+- Report-State (RPT). The client sends a RPT message to the server indicating changes to the request state in the client. The client sends this to inform the server of the actual resource reserved after the server has granted admission. The client can also use Report-State to periodically inform the server of the current state of the client.
+- Delete-Request-State (DRQ). The client sends a DEL message to the server to request state cleanup. This may be the result of QoS resource release by the client.
+- Keep-Alive (KA). Sent by both the client and server for communication failure detection.
+- Synchronize-State-Request (SSQ)/Synchronize-State-Complete (SSC). The server sends the SSQ message to the client requesting current state information. The client re-issues request queries to the server to perform the synchronization, then sends a SSC message to indicate the completion of the synchronization event. A Policy Server MAY support SSQ/SSC synchronization functions if necessary for the Policy Server to acquire or rebuild state from the CMTS. The CMTS MUST support the SSQ/SSC synchronization functions.
+
+Within the IPCablecom Multimedia architecture, the PDP-PEP relations are as follows:
+
+- The Application Manager is a COPS Policy Decision Point (PDP) relative to the Policy Server.
+- The Policy Server is a PEP relative to the Application Manager.
+- The Policy Server is a PDP relative to the CMTS.
+- The CMTS is a PEP relative to the Policy Server.
+
+Although the content of COPS messages required for IPCablecom Multimedia are consistent with the COPS protocol, there is a slight difference in the way the COPS session starts and a relaxation of response ordering requirements. RFC 2748 [7] states:
+
+"The COPS protocol uses a single persistent TCP connection between the PEP and a remote PDP. One PDP implementation per server MUST listen on a well-known TCP port number (COPS=3288 [IANA]). The PEP is responsible for initiating the TCP connection to a PDP."
+
+The last line of the statement says that the PEP is responsible for initiating the TCP connection. In contrast, in the IPCablecom model, the CMTS (PEP) is the one that listens on the assigned port 3918, and it is the Policy Server that MUST initiate the TCP connection to the CMTS. This is the opposite of the model described in the RFC. However, once the TCP connection is in place, the CMTS behaves in a manner consistent with the client, or PEP, in the COPS protocol. Similarly, the Policy Server (PEP) listens on the assigned port 3918 and it is the Application Manager that MUST initiate the TCP connection to the Policy Server.
+
+Note that IPCablecom Multimedia and IPCablecom-T DQoS listen on different ports so that the CMTS may initiate the COPS session with the proper Client-Type.
+
+RFC 2748 also states:
+
+"RPT messages solicited by decisions for a given Client Handle MUST set the Solicited Message flag and MUST be sent in the same order as their corresponding Decision messages were received."
+
+The COPS protocol uses the order of RPT and Decision messages to match requests to responses. In contrast, PacketCable Multimedia implementations MUST use the TransactionID object to match responses with requests and SHOULD send RPT messages as soon as they are ready.
+
+The details of the COPS protocol are provided in RFC 2748. This IETF RFC provides a description of the base COPS protocol, independent of Client-Type. The IPCablecom architecture is also aligned with IETF RFC 3084 [19]. COPS-PR states:
+
+"In COPS-PR, policy requests describe the PEP and its configurable parameters (rather than an operational event). If a change occurs in these basic parameters, an updated request is sent. Hence, requests are issued quite infrequently. Decisions are not necessarily mapped directly to requests, and are issued mostly when the PDP responds to external events or PDP events (policy updates)."
+
+When this concept is mapped to the IPCablecom Multimedia architecture, the PEP issues a Request to the PDP, specifying a Client-Handle. This Client-Handle is then used in all future Decision messages from the PDP to the PEP. These Decision messages carry the Gate Control messages (i.e., Gate-Set, Gate-Info and Gate-Delete) defined for the DQoS and Multimedia Client-Types. The Client-Handle is used to uniquely identify the PDP-PEP association.
+
+In the IPCablecom Multimedia architecture, there can be multiple Application Managers interacting with one or more Policy Servers. There is a single instance of an IPCablecom Multimedia COPS session per TCP connection; where an IPCablecom Multimedia COPS session refers to the Gate messages between the PDP and PEP associated with a single Client-Handle. This means there is one COPS-TCP connection between an Application Manager and a Policy Server. Similarly, there can be one or more Policy Servers talking to one or more CMTSs. When connected to multiple PDPs, the PEP MUST ensure that the Client-Handle used is unique per association.
+
+## 6.4 Gate control protocol message formats
+
+Protocol messages for Gate Control MUST be transported within the COPS protocol messages. The PDP and PEP MUST establish and use a TCP connection for communication, and utilize the mechanisms specified in [11] to secure the communication path.
+
+### 6.4.1 COPS common message format
+
+Each COPS message consists of the COPS header followed by a number of typed objects. The Application Manager, Policy Server and CMTS MUST use the COPS Common Message format as defined below as the message format for all message exchanges. In the object specifications that follow, each row represents a 4-byte word as all objects align on 4-byte word boundaries.
+
+| 0              |       | 1       | 2 | 3           |
+|----------------|-------|---------|---|-------------|
+| Version        | Flags | Op-Code |   | Client-Type |
+| Message Length |       |         |   |             |
+
+Version is a 4-bit field giving the current COPS version number. This field MUST be set to 1.
+
+Flags is a 4-bit field. The least significant bit is the solicited message flag. When a COPS message is sent in response to another message (e.g., a solicited decision sent in response to a request) this flag MUST be set to 1. In other cases (e.g., an unsolicited decision) the flag MUST NOT be set (value = 0). In keeping with the DQoS model, the first Decision message sent in response to a Request message is a solicited response and its solicited message flag MUST be set. All other Decision messages are unsolicited and the solicited message flag MUST be cleared. All other flags MUST be set to zero.
+
+Op-code is a 1-byte unsigned integer field that gives the COPS operation to be performed. COPS operations used in this IPCablecom Recommendation are:
+
+- 1 = Request (REQ);
+- 2 = Decision (DEC);
+- 3 = Report-State (RPT);
+
+- 4 = Delete Request State (DRQ);
+- 5 = Synchronize State Request (SSQ);
+- 6 = Client-Open (OPN);
+- 7 = Client-Accept (CAT);
+- 8 = Client-Close (CC);
+- 9 = Keep-Alive (KA);
+- 10 = Synchronize State Complete (SSC).
+
+Client-Type is a 2-byte unsigned integer identifier. For IPCablecom Multimedia use, the Client-Type MUST be set to IPCablecom Multimedia client (0x800A). For Keep-Alive messages (Op-code = 9), the Client-Type MUST be set to zero as the KA is used for connection verification rather than per-client session verification.
+
+Message Length is a 4-byte unsigned integer value giving the size of the overall message in octets. Messages MUST be aligned on 4-byte boundaries, so the length MUST be a multiple of four.
+
+Following the COPS common header are one or more objects. All the objects MUST conform to the same object format where each object consists of one or more 4-byte words with a four-octet header, using the following format.
+
+|                 |   |       |        |
+|-----------------|---|-------|--------|
+| 0               | 1 | 2     | 3      |
+| Length          |   | C-Num | C-Type |
+| Object Contents |   |       |        |
+
+Length is a 2-byte unsigned integer value that MUST give the number of bytes (including the header) that compose the object. If the original length in octets is not a multiple of four, padding MUST be added to the end of the object so that it is aligned to the next 4-byte boundary.
+
+C-Num identifies the class of information contained in the object, and the C-Type identifies the subtype or version of the information contained in the object. Standard COPS objects (as defined in [7]) used in this Recommendation, and their C-Num values, are:
+
+- 1 = Handle;
+- 2 = Context;
+- 6 = Decision;
+- 8 = Error;
+- 9 = Client Specific Info;
+- 10 = Keep-Alive-Timer;
+- 11 = PEP Identification;
+- 12 = Report Type.
+
+Each of these objects MUST conform to the format and rules relating to the individual object as defined in RFC 2748.
+
+### 6.4.2 Additional COPS objects for gate control
+
+As with the COPS-PR and COPS-RSVP profiles, the IPCablecom Client-Type defines a number of additional object formats. These objects MUST be placed inside a Decision object, C-Num = 6, C-Type = 4 (Client Specific Decision Data) when carried from PDP to PEP in a Decision message. They MUST also be placed in a ClientSI object, C-Num = 9, C-Type = 1 (Signalled ClientSI) when carried from the PEP to the PDP in a Report State message or Client Open message.
+
+These objects are encoded similarly to the client-specific objects for COPS-PR and as in COPS-PR these objects are numbered using a client-specific number space, which is independent of the
+
+top-level COPS object number space. For this reason, the object numbers and types are given as S-Num and S-Type, respectively. S-Num and S-Type MUST be one octet. The COPS Length field MUST be two octets. Additional COPS objects are defined for use by IPCablecom Multimedia in the following clauses.
+
+#### 6.4.2.1 TransactionID
+
+TransactionID is a 2-byte unsigned integer quantity, which contains a token that is used by the Application Manager to match responses from the Policy Server and by the Policy Server to match responses from the CM-ITS to the previous requests. The TransactionID MUST also contain the command type that identifies the action to be taken or response. The TransactionID Object MUST conform to the following format.
+
+|                        |                   |            |
+|------------------------|-------------------|------------|
+| Length = 8             | S-Num = 1         | S-Type = 1 |
+| Transaction Identifier | Gate Command Type |            |
+
+The Transaction Identifier MUST be set to 0 when included in a Gate-Report-State message.
+
+Gate Command Type is a 2-byte unsigned integer value which identifies the Gate Control message type and MUST be one of the following:
+
+|                   |     |
+|-------------------|-----|
+| <Reserved>        | 1-3 |
+| Gate-Set          | 4   |
+| Gate-Set-Ack      | 5   |
+| Gate-Set-Err      | 6   |
+| Gate-Info         | 7   |
+| Gate-Info-Ack     | 8   |
+| Gate-Info-Err     | 9   |
+| Gate-Delete       | 10  |
+| Gate-Delete-Ack   | 11  |
+| Gate-Delete-Err   | 12  |
+| <Reserved>        | 13  |
+| <Reserved>        | 14  |
+| Gate-Report-State | 15  |
+
+#### 6.4.2.2 AMID
+
+AMID, the Application Manager ID, is a 4-byte unsigned integer value which identifies the Application Manager responsible for handling the session. The Application Manager MUST include this object in all messages it issues to the Policy Server. The Policy Server MUST include the received AMID in all messages it issues down to the CM-ITS in response to the messages it receives from the Application Manager. The CM-ITS MUST include the received AMID object in all messages it issues to the Policy Server and likewise, the Policy Server MUST include the received AMID to the Application Manager. The Policy Server may use the AMID in messages from the CM-ITS to resolve the Application Manager to which it may need to generate a message. The AMID object MUST conform to the following format.
+
+|            |           |            |
+|------------|-----------|------------|
+| Length = 8 | S-Num = 2 | S-Type = 1 |
+| AMID       |           |            |
+
+#### 6.4.2.3 SubscriberID
+
+SubscriberID is a 4-byte value giving the IPv4 address (represented as four concatenated octet values) of the subscriber for this service request. This address may be the actual IP address of the subscriber CPE device requesting service (if this address is routable and visible from the head-end) or this address may be the IP address of the CM serving this subscriber (if NAT is performed behind the CM). This object is used to route Gate Control messages within a complex network of PS and CMTS elements. It may also be used in the definition and enforcement of per-subscriber policy rules. The SubscriberID object MUST conform to the following format.
+
+|                                     |           |            |
+|-------------------------------------|-----------|------------|
+| Length = 8                          | S-Num = 3 | S-Type = 1 |
+| SubscriberID (4-octet IPv4 Address) |           |            |
+
+#### 6.4.2.4 GateID
+
+GateID is a 4-byte unsigned integer value which identifies the Gate referenced in the command message, or referenced by the CMTS for a response message. The CMTS MUST ensure the GateID is unique. If the CMTS also supports IPCablecom-T, the GateID MUST NOT duplicate an IPCablecom-T GateID currently in use. The GateID object MUST conform to the following format.
+
+|            |           |            |
+|------------|-----------|------------|
+| Length = 8 | S-Num = 4 | S-Type = 1 |
+| GateID     |           |            |
+
+#### 6.4.2.5 GateSpec
+
+GateSpec defines a specific set of attributes associated with a Gate. The GateSpec object MUST conform to the following format.
+
+|             |                |               |                |
+|-------------|----------------|---------------|----------------|
+| Length = 16 |                | S-Num = 5     | S-Type = 1     |
+| Flags       | DSCP/TOS Field | DSCP/TOS Mask | SessionClassID |
+| Timer T1    |                | Timer T2      |                |
+| Timer T3    |                | Timer T4      |                |
+
+Flags is a 1-byte bit-field value defined as follows:
+
+- Bit 0: direction bit, MUST be either zero for a downstream Gate, or one for an upstream Gate.
+- Bit 1: DSCP/TOS enable bit, MUST be either zero to disable DSCP overwrite, or one to enable.
+- Bits 2-7: reserved, MUST be zero.
+
+SessionClassID is a 1-byte unsigned integer value which identifies the proper admission control policy or parameters to be applied for this Gate. The SessionClassID is a bit field, defined as follows:
+
+- Bit 0-2: Priority, a number from 0 to 7, where 0 is low priority and 7 is high.
+- Bit 3: Preemption, set to enable preemption of bandwidth allocated to lower priority sessions if necessary (if supported).
+- Bit 4-7: Configurable, default to 0.
+
+The priority field describes the relative importance of the session as compared to other sessions generated by the same PDP. The PEP MAY use this value to both implement priority-based admission (in conjunction with the Preemption bit), and to defend the resulting flow from being preempted (see RFC 2751 [22] "defending priority"). The priority granularity of a CMTS may be smaller than the 8 available values. In this case the CMTS SHOULD distribute its levels across the entire priority range. For example, if the CMTS defines 2 priority levels, then it should interpret values 0 to 3 as low priority and values 4 to 7 as high priority. The Policy Server SHOULD normalize or otherwise transform this value to ensure a coherent priority system across the operator's CMTSs, but respond to any AM requests with the original priority value.
+
+The preemption bit is used by a PDP to direct the PEP to apply a priority-based admission control. Preemption support is optional; a PEP MAY ignore this bit. If preemption is not requested by the PDP or not implemented by the PEP, then admission control policy will be on a first-come, first-served basis. If the PEP decides to preempt, it MUST preempt bandwidth from sessions whose priority is lower than this session's priority, beginning with the lowest priority session(s). This bit is not used to control which sessions are preemptable; instead, an unpreemptable session is requested by using the highest priority. If a lower priority session is terminated as a result of preemption, the PEP MUST send a Gate-Report-State message to the PDP with a GateState object Reason field of 1 "Close initiated by CMTS due to reservation reassignment" and transition the gate to the "end" state.
+
+Application Managers that provide novel services MAY use the Configurable field to specify new session classes. The Policy Server MAY support configurable policies based on this value and MAY rewrite this field before forwarding the message to the CMTS. A CMTS MAY implement a novel session class metric using these bits, but the value 0 MUST map to a reasonable default for a PDP that is uninterested in this metric.
+
+The DSCP/TOS Field is a 1-byte bit field [6] defined by the following alternative structures, depending upon network management strategy. This field, combined with the 1-byte DSCP/TOS Mask is used to identify particular bits within the IPv4 DSCP/TOS byte.
+
+| 0                                         | 1 | 2 | 3 | 4 | 5 | 6           | 7           |
+|-------------------------------------------|---|---|---|---|---|-------------|-------------|
+| Differentiated Services Code Point (DSCP) |   |   |   |   |   | Not<br>Used | Not<br>Used |
+
+| 0             | 1 | 2 | 3      | 4 | 5 | 6 | 7           |
+|---------------|---|---|--------|---|---|---|-------------|
+| IP Precedence |   |   | IP TOS |   |   |   | Not<br>Used |
+
+If the 'Enable' bit in the GateSpec Flags field is set, then the CMTS MUST mark the packets traversing the CMTS DSCP/TOS value. If the 'Enable' bit is cleared, then the CMTS MUST NOT perform any marking.
+
+Timers T1, T2, T3 and T4 are 2-byte unsigned integers specified in seconds, and MUST be used as outlined in the Gate Transition Diagram as described in 6.2. A value of zero for T1 indicates that the CMTS provisioned value for the timer MUST be used. T2 corresponds to the DOCSIS Admitted timer and T3 corresponds to the DOCSIS Active timer. All corresponding DOCSIS requirements apply to these timers. Specifically, a zero value for either of these timers indicates that the corresponding timer MUST be disabled.
+
+#### 6.4.2.6 Classifier
+
+The Classifier object specifies the packet matching rules associated with a Gate. As defined in clauses 6.4.3.1 and 6.4.3.2, multiple Classifier objects may be included in the Gate-Set to allow for complex classifier rules. The Classifier object MUST conform to the following format.
+
+|                                   |                  |               |
+|-----------------------------------|------------------|---------------|
+| Length = 24                       | S-Num = 6        | S-Type = 1    |
+| Protocol ID                       | DSCP/TOS Field   | DSCP/TOS Mask |
+| Source IP Address (4-octets)      |                  |               |
+| Destination IP Address (4-octets) |                  |               |
+| Source Port                       | Destination Port |               |
+| Priority                          | Reserved         |               |
+
+Source IP Address and Destination IP Address MUST be a pair of 4-octet IPv4 addresses, or zero for no match (i.e., a wildcard specification that will match any packet).
+
+Source Port and Destination Port MUST be a pair of 2-byte unsigned integer values, or zero for no match.
+
+Protocol ID MUST conform to clause B.C.2.1.5.2 of [1], or zero for no match.
+
+DSCP/TOS Field is a 1-byte bit field which MUST conform to the following alternative structures:
+
+|                                           |   |   |   |   |   |          |        |
+|-------------------------------------------|---|---|---|---|---|----------|--------|
+| 0                                         | 1 | 2 | 3 | 4 | 5 | 6        | 7      |
+| Differentiated Services Code Point (DSCP) |   |   |   |   |   | Not Used | Enable |
+
+|               |   |   |        |   |   |   |        |
+|---------------|---|---|--------|---|---|---|--------|
+| 0             | 1 | 2 | 3      | 4 | 5 | 6 | 7      |
+| IP Precedence |   |   | IP TOS |   |   |   | Enable |
+
+DSCP/TO Mask is a 1-byte bit field providing a bit mask used to select relevant bits from the accompanying DSCP/TO Field value.
+
+If the 'Enable' bit is set, then the CMTS MUST use these values to construct the IP TOS Range and Mask field specified in its DSx messaging. If the 'Enable' bit is cleared, then the CMTS MUST omit the IP TOS Range and Mask values from its DSx messaging and exclude the IP TOS byte from the packet classification process.
+
+Priority is a 1-byte field that allows differentiation between classifiers that might overlap. A default value of 64 SHOULD be used if a specific priority value is not required. For further discussion of the Priority field, refer to B.C.2.1.3.5 of [1].
+
+#### 6.4.2.7 Traffic profiles
+
+There are three different ways to express a traffic profile. The traffic profile can be expressed via a FlowSpec, a DOCSIS Service Class Name, or DOCSIS-specific parameters. The three methods are distinguished via a different S-Type value in the Traffic Profile (S-Num = 7) object. S-Type of 1 indicates the object contains a traffic profile specified in RSVP FlowSpec format. S-Type of 2 indicates the object contains a traffic profile specified in DOCSIS Service Class Name format. S-Type of 3 or greater indicates the object contains a traffic profile that is specified via DOCSIS-specific parameters.
+
+All Traffic Profiles utilize "replace" semantics, meaning that the envelopes present in this Traffic Profile replace all existing envelopes associated with the Gate and corresponding Service Flow. Thus, all traffic parameters associated with a given Gate MUST be included in every message that includes a Traffic Profile.
+
+All Traffic Profiles share a common field known as the Envelope Field. This field is a bit field that signals the envelope types (i.e., Authorized, Reserved, and Committed) that are present in the object. A value of 1 in a given bit field indicates that the envelope type is present in the Traffic Profile.
+
+- Bit 0: Authorized Envelope.
+- Bit 1: Reserved Envelope.
+- Bit 2: Committed Envelope.
+
+Thus a bit pattern of 001 (or 0x01) indicates the presence of only the Authorized Envelope, while a value of 111 (or 0x7) indicates the presence of all three envelopes. Only the following values are legal: 001, 011 and 111; the Envelope Field MUST be set to one of these three legal values. Further limitations on the value of the Envelope Field may be a function of the current state of the Gate. Refer to 6.2 for more information.
+
+For the Traffic Profile formats that allow multiple sets of envelope parameters, the mapping of envelope parameter sets follows one of the following methods:
+
+If all of the envelope types that are indicated in the envelope field share a common set of envelope parameters, then the PDP SHOULD ensure that exactly one set of envelope parameters are present in the traffic profile. This allows for the most efficient transmission and processing of the Traffic Profile throughout the system.
+
+Otherwise, the PDP MUST ensure that exactly one set of envelope parameters is included for each of the envelope types that are indicated in the envelope field. The proper order of the envelope parameter sets is shown in the appropriate message diagram in clauses 6.4.2.7.1 and 6.4.2.7.3 thru 6.4.2.7.8.
+
+While all Traffic Profiles end up providing QoS on the access network, it is important to note several subtle differences between the signalling mechanisms. As noted previously, the conversion of a FlowSpec (S-Type 1) to DOCSIS parameters by the CMTS is generally less efficient than specifying the DOCSIS parameters themselves. That said, specifying DOCSIS parameters explicitly (S-Types 3-7) is not a panacea either, the QoS MIB only logs QoS information about named Service Flows in its ServiceFlowLogTable. Thus, only flows created via S-Type 2 will have logged QoS information in this table. For some this may not be a major issue but, for debugging and just general operational tracking, this subtlety should be taken into account by operators and Application Manager vendors evaluating the Traffic Profile signalling alternatives provided by this Recommendation.
+
+##### 6.4.2.7.1 Flow spec
+
+The FlowSpec object defines the Traffic Profile associated with a Gate through an RSVP-like parameterization scheme. The mapping of these parameters to DOCSIS parameters is specified in clause 8. The FlowSpec object MUST conform to the following specification:
+
+|                                                    |                |           |            |
+|----------------------------------------------------|----------------|-----------|------------|
+| Length = 36 or 64 or 92                            |                | S-Num = 7 | S-Type = 1 |
+| Envelope                                           | Service Number | Reserved  | Reserved   |
+| Authorized Envelope                                |                |           |            |
+| Token Bucket Rate [r] (IEEE floating point number) |                |           |            |
+| Token Bucket Size [b] (IEEE floating point number) |                |           |            |
+| Peak Data Rate (p) (IEEE floating point number)    |                |           |            |
+| Minimum Policed Unit [m] (integer)                 |                |           |            |
+| Maximum Packet Size [M] (integer)                  |                |           |            |
+| Rate [R] (IEEE floating point number)              |                |           |            |
+| Slack Term [S] (integer)                           |                |           |            |
+| Reserved Envelope (optional)                       |                |           |            |
+| Token Bucket Rate [r] (IEEE floating point number) |                |           |            |
+| Token Bucket Size [b] (IEEE floating point number) |                |           |            |
+| Peak Data Rate (p) (IEEE floating point number)    |                |           |            |
+| Minimum Policed Unit [m] (integer)                 |                |           |            |
+| Maximum Packet Size [M] (integer)                  |                |           |            |
+| Rate [R] (IEEE floating point number)              |                |           |            |
+| Slack Term [S] (integer)                           |                |           |            |
+| Committed Envelope (optional)                      |                |           |            |
+| Token Bucket Rate [r] (IEEE floating point number) |                |           |            |
+| Token Bucket Size [b] (IEEE floating point number) |                |           |            |
+| Peak Data Rate (p) (IEEE floating point number)    |                |           |            |
+| Minimum Policed Unit [m] (integer)                 |                |           |            |
+| Maximum Packet Size [M] (integer)                  |                |           |            |
+| Rate [R] (IEEE floating point number)              |                |           |            |
+| Slack Term [S] (integer)                           |                |           |            |
+
+The Service Number field corresponds to the RSVP FlowSpec service number as defined in [3]. If Service Number is set to five, this indicates Controlled Load service and the CMTS MUST utilize only the TSpec values (i.e., token bucket parameters) to perform the necessary authorization, reservation and commit operations. For Controlled Load service, the CMTS MUST ignore the RSpec R and S fields.
+
+If Service Number is set to two, this signals Guaranteed service and the CMTS MUST utilize both the TSpec and RSpec values to perform the necessary authorization, reservation and commit operations.
+
+The values r, b, p, m, M, R, and s are defined and described in clause 9.
+
+##### 6.4.2.7.2 DOCSIS service class name
+
+The DOCSIS Service Class Name object defines the preconfigured Service Class Name associated with a Gate. The DOCSIS Service Class Name object MUST conform to the following specification:
+
+|                               |          |           |            |
+|-------------------------------|----------|-----------|------------|
+| Length = 12 or 16 or 20 or 24 |          | S-Num = 7 | S-Type = 2 |
+| Envelope                      | Reserved | Reserved  | Reserved   |
+| Service Class Name            |          |           |            |
+| -----                         |          |           |            |
+| -----                         |          |           |            |
+| -----                         |          |           |            |
+
+The Service Class Name MUST be 2-16 bytes of null-terminated ASCII string. (Refer to B.C.2.2.3.4 of [1]). This name MUST be padded with null bytes to align on a 4-byte boundary.
+
+Note that unlike a FlowSpec Traffic Profile which allows for different parameters to be associated with each Envelope, the DOCSIS Service Class Name Traffic Profile supports different Gate states as specified by the Envelope field, but each Envelope is defined by the same associated DOCSIS Service Class Name. This allows for having two-phase commit operations utilizing the DOCSIS Service Class Names, but each Envelope must be identical. Also note, that it is possible to change the DOCSIS Service Class Name associated with a Gate, but that such a change applies to all Envelopes associated with a given Gate.
+
+##### 6.4.2.7.3 Best effort service
+
+The Best Effort object defines the Traffic Profile associated with a Gate through an upstream DOCSIS-specific parameterization scheme. The Best Effort object MUST conform to the following specification:
+
+|                                                   |          |           |            |  |  |  |
+|---------------------------------------------------|----------|-----------|------------|--|--|--|
+| Length = 32, 56 or 80                             |          | S-Num = 7 | S-Type = 3 |  |  |  |
+| Envelope                                          | Reserved | Reserved  | Reserved   |  |  |  |
+| Authorized Envelope                               |          |           |            |  |  |  |
+| Traffic Priority                                  | Reserved |           |            |  |  |  |
+| Request Transmission Policy                       |          |           |            |  |  |  |
+| Maximum Sustained Traffic Rate                    |          |           |            |  |  |  |
+| Maximum Traffic Burst                             |          |           |            |  |  |  |
+| Minimum Reserved Traffic Rate                     |          |           |            |  |  |  |
+| Assumed Minimum Reserved Traffic Rate Packet Size | Reserved |           |            |  |  |  |
+| Reserved Envelope (optional)                      |          |           |            |  |  |  |
+| Traffic Priority                                  | Reserved |           |            |  |  |  |
+| Request Transmission Policy                       |          |           |            |  |  |  |
+| Maximum Sustained Traffic Rate                    |          |           |            |  |  |  |
+| Maximum Traffic Burst                             |          |           |            |  |  |  |
+| Minimum Reserved Traffic Rate                     |          |           |            |  |  |  |
+| Assumed Minimum Reserved Traffic Rate Packet Size | Reserved |           |            |  |  |  |
+| Committed Envelope (optional)                     |          |           |            |  |  |  |
+| Traffic Priority                                  | Reserved |           |            |  |  |  |
+| Request Transmission Policy                       |          |           |            |  |  |  |
+| Maximum Sustained Traffic Rate                    |          |           |            |  |  |  |
+| Maximum Traffic Burst                             |          |           |            |  |  |  |
+| Minimum Reserved Traffic Rate                     |          |           |            |  |  |  |
+| Assumed Minimum Reserved Traffic Rate Packet Size | Reserved |           |            |  |  |  |
+
+Traffic Priority is a 1-byte unsigned integer field specifying the relative priority assigned to the Service Flow in comparison with other flows. This field is fully defined in B.C.2.2.5.1 of [1]. A default Traffic Priority of 0 SHOULD be used if a specific Traffic Priority value is not required.
+
+Request/Transmission Policy is a 4-byte bit field as defined in B.C.2.2.6.3 of [1]. A default Request/Transmission policy of 0 SHOULD be used if a specific Request/Transmission Policy value is not required.
+
+Maximum Sustained Traffic Rate is a 4-byte unsigned integer field specifying the rate parameter, in bits/s, for a token-bucket-based rate limit for this Service Flow. This field is fully defined in B.C.2.2.5.2 of [1]. A value of 0 indicates that no explicitly-enforced Maximum Sustained Rate is requested. A default Maximum Sustained Traffic Rate of 0 SHOULD be used if a specific Maximum Sustained Traffic Rate is not required.
+
+Maximum Traffic Burst is a 4-byte unsigned integer field specifying the token bucket size, in bytes, for a token-bucket-based rate limit for this Service Flow. This field is fully defined in B.C.2.2.5.3 of [1]. A default Maximum Traffic Burst of 3044 bytes SHOULD be used if a specific Maximum Traffic Burst is not required. The value of this parameter has no effect unless a non-zero value has been provided for the Maximum Sustained Traffic Rate parameter.
+
+Minimum Reserved Traffic Rate is a 4-byte unsigned integer field specifying the minimum rate, in bits/s, reserved for this Service Flow. This field is fully defined in B.C.2.2.5.4 of [1]. A default Minimum Reserved Traffic Rate of 0 SHOULD be used if a specific Minimum Reserved Traffic Rate is not required.
+
+Assumed Minimum Reserved Traffic Rate Packet Size is a 2-byte unsigned integer field specifying an assumed minimum packet size, in bytes, for which the Minimum Reserved Traffic Rate will be provided for this flow. This field is fully defined in B.C.2.2.5.5 of [1]. A default Assumed Minimum Reserved Traffic Rate Packet Size of 0 SHOULD be used if a specific Assumed Minimum Reserved Traffic Rate Packet size is not required. Upon receipt of a value of 0 the CMTS MUST utilize its implementation-specific default size for this parameter, not 0 bytes.
+
+##### 6.4.2.7.4 Non-real-time polling service
+
+The Non-Real-Time Polling object defines the Traffic Profile associated with an upstream Gate through a DOCSIS-specific parameterization scheme. The Non-Real-Time Polling object MUST conform to the following specification:
+
+|                                                   |          |           |            |  |  |  |
+|---------------------------------------------------|----------|-----------|------------|--|--|--|
+| Length = 36, 64 or 92                             |          | S-Num = 7 | S-Type = 4 |  |  |  |
+| Envelope                                          | Reserved | Reserved  | Reserved   |  |  |  |
+| Authorized Envelope                               |          |           |            |  |  |  |
+| Traffic Priority                                  | Reserved |           |            |  |  |  |
+| Request Transmission Policy                       |          |           |            |  |  |  |
+| Maximum Sustained Traffic Rate                    |          |           |            |  |  |  |
+| Maximum Traffic Burst                             |          |           |            |  |  |  |
+| Minimum Reserved Traffic Rate                     |          |           |            |  |  |  |
+| Assumed Minimum Reserved Traffic Rate Packet Size | Reserved |           |            |  |  |  |
+| Nominal Polling Interval                          |          |           |            |  |  |  |
+| Reserved Envelope (optional)                      |          |           |            |  |  |  |
+| Traffic Priority                                  | Reserved |           |            |  |  |  |
+| Request Transmission Policy                       |          |           |            |  |  |  |
+| Maximum Sustained Traffic Rate                    |          |           |            |  |  |  |
+| Maximum Traffic Burst                             |          |           |            |  |  |  |
+| Minimum Reserved Traffic Rate                     |          |           |            |  |  |  |
+| Assumed Minimum Reserved Traffic Rate Packet Size | Reserved |           |            |  |  |  |
+| Nominal Polling Interval                          |          |           |            |  |  |  |
+| Committed Envelope (optional)                     |          |           |            |  |  |  |
+| Traffic Priority                                  | Reserved |           |            |  |  |  |
+| Request Transmission Policy                       |          |           |            |  |  |  |
+| Maximum Sustained Traffic Rate                    |          |           |            |  |  |  |
+| Maximum Traffic Burst                             |          |           |            |  |  |  |
+| Minimum Reserved Traffic Rate                     |          |           |            |  |  |  |
+| Assumed Minimum Reserved Traffic Rate Packet Size | Reserved |           |            |  |  |  |
+| Nominal Polling Interval                          |          |           |            |  |  |  |
+
+Traffic Priority is a 1-byte unsigned integer field specifying the relative priority assigned to the Service Flow in comparison with other flows. This field is fully defined in B.C.2.2.5.1 of [1]. A default Traffic Priority of 0 SHOULD be used if a specific Traffic Priority value is not required.
+
+Request/Transmission Policy is a 4-byte bit field as defined in B.C.2.2.6.3 of [1].
+
+NOTE – For this Service Flow Scheduling Type there is no default value for Request/Transmission Policy and all values (including 0) have meaning in DOCSIS.
+
+Maximum Sustained Traffic Rate is a 4-byte unsigned integer field specifying the rate parameter, in bits/s, for a token-bucket-based rate limit for this Service Flow. This field is fully defined in B.C.2.2.5.2 of [1]. A value of 0 indicates that no explicitly-enforced Maximum Sustained Rate is requested. A default Maximum Sustained Traffic Rate of 0 SHOULD be used if a specific Maximum Sustained Traffic Rate is not required.
+
+Maximum Traffic Burst is a 4-byte unsigned integer field specifying the token bucket size, in bytes, for a token-bucket-based rate limit for this Service Flow. This field is fully defined in B.C.2.2.5.3 of [1]. A default Maximum Traffic Burst of 3044 bytes SHOULD be used if a specific Maximum Traffic Burst is not required. The value of this parameter has no effect unless a non-zero value has been provided for the Maximum Sustained Traffic Rate parameter.
+
+Minimum Reserved Traffic Rate is a 4-byte unsigned integer field specifying the minimum rate, in bits/s, reserved for this Service Flow. This field is fully defined in B.C.2.2.5.4 of [1]. A default Minimum Reserved Traffic Rate of 0 SHOULD be used if a specific Minimum Reserved Traffic Rate is not required.
+
+Assumed Minimum Reserved Traffic Rate Packet Size is a 2-byte unsigned integer field specifying an assumed minimum packet size, in bytes, for which the Minimum Reserved Traffic Rate will be provided for this flow. This field is fully defined in B.C.2.2.5.5 of [1]. A default Assumed Minimum Reserved Traffic Rate Packet Size of 0 SHOULD be used if a specific Assumed Minimum Reserved Traffic Rate Packet size is not required. Upon receipt of a value of 0 the CMTS MUST utilize its implementation-specific default size for this parameter, not 0 bytes.
+
+Nominal Polling Interval is a 4-byte unsigned integer field specifying the nominal interval (in units of microseconds) between successive unicast request opportunities for this Service Flow on the upstream channel. This field is fully defined in B.C.2.2.6.4 of [1]. A default Nominal Polling Interval of 0 SHOULD be used if a specific Nominal Polling Interval is not required. Upon receipt of a value of 0 the CMTS MUST utilize its implementation-specific default size for this parameter – not 0 microseconds.
+
+##### 6.4.2.7.5 Real-time polling service
+
+The Real-Time Polling object defines the Traffic Profile associated with an upstream Gate through a DOCSIS-specific parameterization scheme. The Real-Time Polling object MUST conform to the following specification:
+
+|                                                   |          |           |            |  |  |
+|---------------------------------------------------|----------|-----------|------------|--|--|
+| Length = 36, 64 or 92                             |          | S-Num = 7 | S-Type = 5 |  |  |
+| Envelope                                          | Reserved | Reserved  | Reserved   |  |  |
+| Authorized Envelope                               |          |           |            |  |  |
+| Request Transmission Policy                       |          |           |            |  |  |
+| Maximum Sustained Traffic Rate                    |          |           |            |  |  |
+| Maximum Traffic Burst                             |          |           |            |  |  |
+| Minimum Reserved Traffic Rate                     |          |           |            |  |  |
+| Assumed Minimum Reserved Traffic Rate Packet Size |          | Reserved  |            |  |  |
+| Nominal Polling Interval                          |          |           |            |  |  |
+| Tolerated Poll Jitter                             |          |           |            |  |  |
+| Reserved Envelope (optional)                      |          |           |            |  |  |
+| Request Transmission Policy                       |          |           |            |  |  |
+| Maximum Sustained Traffic Rate                    |          |           |            |  |  |
+| Maximum Traffic Burst                             |          |           |            |  |  |
+| Minimum Reserved Traffic Rate                     |          |           |            |  |  |
+| Assumed Minimum Reserved Traffic Rate Packet Size |          | Reserved  |            |  |  |
+| Nominal Polling Interval                          |          |           |            |  |  |
+| Tolerated Poll Jitter                             |          |           |            |  |  |
+| Committed Envelope (optional)                     |          |           |            |  |  |
+| Request Transmission Policy                       |          |           |            |  |  |
+| Maximum Sustained Traffic Rate                    |          |           |            |  |  |
+| Maximum Traffic Burst                             |          |           |            |  |  |
+| Minimum Reserved Traffic Rate                     |          |           |            |  |  |
+| Assumed Minimum Reserved Traffic Rate Packet Size |          | Reserved  |            |  |  |
+| Nominal Polling Interval                          |          |           |            |  |  |
+| Tolerated Poll Jitter                             |          |           |            |  |  |
+
+Request/Transmission Policy is a 4-byte bit field as defined in B.C.2.2.6.3 of [1].
+
+NOTE – For this Service Flow Scheduling Type there is no default value for Request/Transmission Policy and all values (including 0) have meaning in DOCSIS.
+
+Maximum Sustained Traffic Rate is a 4-byte unsigned integer field specifying the rate parameter, in bits/s, for a token-bucket-based rate limit for this Service Flow. This field is fully defined in B.C.2.2.5.2 of [1]. A value of 0 indicates that no explicitly-enforced Maximum Sustained Rate is requested. A default Maximum Sustained Traffic Rate of 0 SHOULD be used if a specific Maximum Sustained Traffic Rate is not required.
+
+Maximum Traffic Burst is a 4-byte unsigned integer field specifying the token bucket size, in bytes, for a token-bucket-based rate limit for this Service Flow. This field is fully defined in B.C.2.2.5.3 of [1]. A default Maximum Traffic Burst of 3044 bytes SHOULD be used if a specific
+
+Maximum Traffic Burst is not required. The value of this parameter has no effect unless a non-zero value has been provided for the Maximum Sustained Traffic Rate parameter.
+
+Minimum Reserved Traffic Rate is a 4-byte unsigned integer field specifying the minimum rate, in bits/s, reserved for this Service Flow. This field is fully defined in B.C.2.2.5.4 of [1]. A default Minimum Reserved Traffic Rate of 0 SHOULD be used if a specific Minimum Reserved Traffic Rate is not required.
+
+Assumed Minimum Reserved Traffic Rate Packet Size is a 2-byte unsigned integer field specifying an assumed minimum packet size, in bytes, for which the Minimum Reserved Traffic Rate will be provided for this flow. This field is fully defined in B.C.2.2.5.5 of [1]. A default Assumed Minimum Reserved Traffic Rate Packet Size of 0 SHOULD be used if a specific Assumed Minimum Reserved Traffic Rate Packet size is not required. Upon receipt of a value of 0 the CMTS MUST utilize its implementation-specific default size for this parameter, not 0 bytes.
+
+Nominal Polling Interval is a 4-byte unsigned integer field specifying the nominal interval (in units of microseconds) between successive unicast request opportunities for this Service Flow on the upstream channel. This field is fully defined in B.C.2.2.6.4 of [1]. For this Service Flow Scheduling Type there is no default value for Nominal Polling Interval.
+
+Tolerated Polling Jitter is a 4-byte unsigned integer field specifying the maximum amount of time that the unicast request interval may be delayed from the nominal periodic schedule (measured in microseconds). This field is fully defined in B.C.2.2.6.5 of [1]. A default Tolerated Polling Jitter of 0 SHOULD be used if a specific Tolerated Polling Jitter is not required. Upon receipt of a value of 0 the CMTS MUST utilize its implementation-specific default size for this parameter, not 0 microseconds.
+
+##### 6.4.2.7.6 Unsolicited grant service
+
+The Unsolicited Grant object defines the Traffic Profile associated with an upstream Gate through a DOCSIS-specific parameterization scheme. The Unsolicited Grant object MUST conform to the following specification:
+
+|                               |          |                 |            |
+|-------------------------------|----------|-----------------|------------|
+| Length = 24, 40, or 56        |          | S-Num = 7       | S-Type = 6 |
+| Envelope                      | Reserved | Reserved        | Reserved   |
+| Authorized Envelope           |          |                 |            |
+| Request Transmission Policy   |          |                 |            |
+| Unsolicited Grant Size        |          | Grants/Interval | Reserved   |
+| Nominal Grant Interval        |          |                 |            |
+| Tolerated Grant Jitter        |          |                 |            |
+| Reserved Envelope (optional)  |          |                 |            |
+| Request Transmission Policy   |          |                 |            |
+| Unsolicited Grant Size        |          | Grants/Interval | Reserved   |
+| Nominal Grant Interval        |          |                 |            |
+| Tolerated Grant Jitter        |          |                 |            |
+| Committed Envelope (optional) |          |                 |            |
+| Request Transmission Policy   |          |                 |            |
+| Unsolicited Grant Size        |          | Grants/Interval | Reserved   |
+| Nominal Grant Interval        |          |                 |            |
+| Tolerated Grant Jitter        |          |                 |            |
+
+Request/Transmission Policy is a 4-byte bit field as defined in B.C.2.2.6.3 of [1].
+
+NOTE – For this Service Flow Scheduling Type there is no default value for Request/Transmission Policy and all values (including 0) have meaning in DOCSIS.
+
+Unsolicited Grant Size is a 2-byte unsigned integer field specifying the grant size (in bytes) as defined in B.C.2.2.6.6 of [1]. There is no default value of Unsolicited Grant Size.
+
+Grants per Interval is a 1-byte unsigned integer field specifying the number of grants per Nominal Grant Interval as defined in B.C.2.2.6.9 of [1]. There is no default value of Grants per Interval, but a value of 1 is recommended.
+
+Nominal Grant Interval is a 4-byte unsigned integer field specifying the nominal time between successive data grant opportunities for this Service Flow (in units of microseconds) as defined in B.C.2.2.6.7 of [1]. There is no default value of Nominal Grant Interval.
+
+Tolerated Grant Jitter is a 4-byte unsigned integer field specifying the maximum amount of time that transmission opportunities may be delayed from the nominal periodic schedule (in units of microseconds) as defined in B.C.2.2.6.8 of [1]. There is no default value for Tolerated Grant Jitter.
+
+##### 6.4.2.7.7 Unsolicited grant service with activity detection
+
+The Unsolicited Grant with Activity Detection object defines the Traffic Profile associated with an upstream Gate through a DOCSIS-specific parameterization scheme. The Unsolicited Grant with Activity Detection object MUST conform to the following specification:
+
+|                               |          |                 |            |
+|-------------------------------|----------|-----------------|------------|
+| Length = 32, 56 or 80         |          | S-Num = 7       | S-Type = 7 |
+| Envelope                      | Reserved | Reserved        | Reserved   |
+| Authorized Envelope           |          |                 |            |
+| Request Transmission Policy   |          |                 |            |
+| Unsolicited Grant Size        |          | Grants/Interval | Reserved   |
+| Nominal Grant Interval        |          |                 |            |
+| Tolerated Grant Jitter        |          |                 |            |
+| Nominal Polling Interval      |          |                 |            |
+| Tolerated Poll Jitter         |          |                 |            |
+| Reserved Envelope (optional)  |          |                 |            |
+| Request Transmission Policy   |          |                 |            |
+| Unsolicited Grant Size        |          | Grants/Interval | Reserved   |
+| Nominal Grant Interval        |          |                 |            |
+| Tolerated Grant Jitter        |          |                 |            |
+| Nominal Polling Interval      |          |                 |            |
+| Tolerated Poll Jitter         |          |                 |            |
+| Committed Envelope (optional) |          |                 |            |
+| Request Transmission Policy   |          |                 |            |
+| Unsolicited Grant Size        |          | Grants/Interval | Reserved   |
+| Nominal Grant Interval        |          |                 |            |
+| Tolerated Grant Jitter        |          |                 |            |
+| Nominal Polling Interval      |          |                 |            |
+| Tolerated Poll Jitter         |          |                 |            |
+
+Request/Transmission Policy is a 4-byte bit field as defined in B.C.2.2.6.3 of [1].
+
+NOTE – For this Service Flow Scheduling Type there is no default value for Request/Transmission Policy and all values (including 0) have meaning in DOCSIS.
+
+Unsolicited Grant Size is a 2-byte unsigned integer field specifying the grant size (in bytes) as defined in B.C.2.2.6.6 of [1]. There is no default value of Unsolicited Grant Size.
+
+Grants per Interval is a 1-byte unsigned integer field specifying the number of grants per Nominal Grant Interval as defined in B.C.2.2.6.9 of [1]. There is no default value of Grants per Interval, but a value of 1 is recommended.
+
+Nominal Grant Interval is a 4-byte unsigned integer field specifying the nominal time between successive data grant opportunities for this Service Flow (in units of microseconds) as defined in B.C.2.2.6.7 of [1]. There is no default value of Nominal Grant Interval.
+
+Tolerated Grant Jitter is a 4-byte unsigned integer field specifying the maximum amount of time that transmission opportunities may be delayed from the nominal periodic schedule (in units of microseconds) as defined in B.C.2.2.6.8 of [1]. There is no default value of Tolerated Grant Jitter.
+
+Nominal Polling Interval is a 4-byte unsigned integer field specifying the nominal interval (in units of microseconds) between successive unicast request opportunities for this Service Flow on the upstream channel. This field is fully defined in B.C.2.2.6.4 of [1]. There is no default value of Nominal Polling Interval.
+
+Tolerated Polling Jitter is a 4-byte unsigned integer field specifying the maximum amount of time that the unicast request interval may be delayed from the nominal periodic schedule (measured in microseconds). This field is fully defined in B.C.2.2.6.5 of [1]. Upon receipt of a value of 0 the CMTS MUST utilize its implementation-specific default size for this parameter, not 0 microseconds.
+
+##### 6.4.2.7.8 Downstream service
+
+The Downstream object defines the Traffic Profile associated with a Gate through a downstream DOCSIS-specific parameterization scheme. The Downstream object MUST conform to the following specification:
+
+|                                                   |          |           |            |  |  |  |  |  |
+|---------------------------------------------------|----------|-----------|------------|--|--|--|--|--|
+| Length = 32, 56 or 80                             |          | S-Num = 7 | S-Type = 8 |  |  |  |  |  |
+| Envelope                                          | Reserved | Reserved  | Reserved   |  |  |  |  |  |
+| Authorized Envelope                               |          |           |            |  |  |  |  |  |
+| Traffic Priority                                  | Reserved |           |            |  |  |  |  |  |
+| Maximum Sustained Traffic Rate                    |          |           |            |  |  |  |  |  |
+| Maximum Traffic Burst                             |          |           |            |  |  |  |  |  |
+| Minimum Reserved Traffic Rate                     |          |           |            |  |  |  |  |  |
+| Assumed Minimum Reserved Traffic Rate Packet Size |          | Reserved  |            |  |  |  |  |  |
+| Maximum Downstream Latency                        |          |           |            |  |  |  |  |  |
+| Reserved Envelope (optional)                      |          |           |            |  |  |  |  |  |
+| Traffic Priority                                  | Reserved |           |            |  |  |  |  |  |
+| Maximum Sustained Traffic Rate                    |          |           |            |  |  |  |  |  |
+| Maximum Traffic Burst                             |          |           |            |  |  |  |  |  |
+| Minimum Reserved Traffic Rate                     |          |           |            |  |  |  |  |  |
+| Assumed Minimum Reserved Traffic Rate Packet Size |          | Reserved  |            |  |  |  |  |  |
+| Maximum Downstream Latency                        |          |           |            |  |  |  |  |  |
+| Committed Envelope (optional)                     |          |           |            |  |  |  |  |  |
+| Traffic Priority                                  | Reserved |           |            |  |  |  |  |  |
+| Maximum Sustained Traffic Rate                    |          |           |            |  |  |  |  |  |
+| Maximum Traffic Burst                             |          |           |            |  |  |  |  |  |
+| Minimum Reserved Traffic Rate                     |          |           |            |  |  |  |  |  |
+| Assumed Minimum Reserved Traffic Rate Packet Size |          | Reserved  |            |  |  |  |  |  |
+| Maximum Downstream Latency                        |          |           |            |  |  |  |  |  |
+
+Traffic Priority is a 1-byte unsigned integer field specifying the relative priority assigned to the Service Flow in comparison with other flows. This field is fully defined in B.C.2.2.5.1 of [1]. A default Traffic Priority of 0 SHOULD be used if a specific Traffic Priority value is not required.
+
+Maximum Sustained Traffic Rate is a 4-byte unsigned integer field specifying the rate parameter, in bits/s, for a token-bucket-based rate limit for this Service Flow. This field is fully defined in B.C.2.2.5.2 of [1]. A value of 0 indicates that no explicitly-enforced Maximum Sustained Rate is requested. A default Maximum Sustained Traffic Rate of 0 SHOULD be used if a specific Maximum Sustained Traffic Rate is not required.
+
+Maximum Traffic Burst is a 4-byte unsigned integer field specifying the token bucket size, in bytes, for a token-bucket-based rate limit for this Service Flow. This field is fully defined in B.C.2.2.5.3 of [1]. A default Maximum Traffic Burst of 3044 bytes SHOULD be used if a specific Maximum Traffic Burst is not required. The value of this parameter has no effect unless a non-zero value has been provided for the Maximum Sustained Traffic Rate parameter.
+
+Minimum Reserved Traffic Rate is a 4-byte unsigned integer field specifying the minimum rate, in bits/s, reserved for this Service Flow. This field is fully defined in B.C.2.2.5.4 of [1]. A default
+
+Minimum Reserved Traffic Rate of 0 SHOULD be used if a specific Minimum Reserved Traffic Rate is not required.
+
+Assumed Minimum Reserved Traffic Rate Packet Size is a 2-byte unsigned integer field specifying an assumed minimum packet size, in bytes, for which the Minimum Reserved Traffic Rate will be provided for this flow. This field is fully defined in B.C.2.2.5.5 of [1]. A default Assumed Minimum Reserved Traffic Rate Packet Size of 0 SHOULD be used if a specific Assumed Minimum Reserved Traffic Rate Packet size is not required. Upon receipt of a value of 0 the CMTS MUST utilize its implementation-specific default size for this parameter, not 0 bytes.
+
+Maximum Downstream Latency is a 4-byte unsigned integer field specifying the maximum latency between reception of a packet on the CMTS's NSI and the forwarding of the packet on its RF interface as defined in B.C.2.2.7.1 of [1]. A default Maximum Downstream Latency of 0 SHOULD be used if a specific Maximum Downstream Latency is not required. Upon receipt of a value of 0, the CMTS MUST NOT include this parameter in its DOCSIS signalling for this Service Flow.
+
+#### 6.4.2.8 Event generation info
+
+The Event Generation Info object contains all the information necessary to support the event messages as specified and required in ITU-T Rec. J.164. The Event Generation Info object MUST conform to the following specification:
+
+|                                                       |           |            |  |  |
+|-------------------------------------------------------|-----------|------------|--|--|
+| Length = 44                                           | S-Num = 8 | S-Type = 1 |  |  |
+| Primary-Record-Keeping-Server-IP-Address (4-octets)   |           |            |  |  |
+| Primary-Record-Keeping-Server-Port                    | Reserved  |            |  |  |
+| Secondary-Record-Keeping-Server-IP-Address (4-octets) |           |            |  |  |
+| Secondary-Record-Keeping-Server-Port                  | Reserved  |            |  |  |
+| Billing-Correlation-ID (24-bytes)                     |           |            |  |  |
+| -----                                                 |           |            |  |  |
+| -----                                                 |           |            |  |  |
+| -----                                                 |           |            |  |  |
+| -----                                                 |           |            |  |  |
+| -----                                                 |           |            |  |  |
+
+Primary-Record-Keeping-Server-IP-Address is a 4-byte field which MUST contain the IPv4 address of the primary RKS to whom event records are to be sent.
+
+Primary-Record-Keeping-Server-Port field is a 2-byte unsigned integer which MUST contain the port number on the primary RKS where event records are to be sent.
+
+Secondary-Record-Keeping-Server-IP-Address is a 4-byte field which MUST contain the IPv4 address of the secondary RKS to whom records are to be sent if the primary RKS is unavailable.
+
+Secondary-Record-Keeping-Server-Port is a 2-byte unsigned integer which MUST contain the port number on the secondary RKS where event records are to be sent.
+
+Billing-Correlation-ID is a 24-byte field which MUST contain the identifier assigned by the AM or PS for all records related to this session. See [10] for the definition and format of this attribute.
+
+#### 6.4.2.9 Volume-based usage limit
+
+The Volume-Based Usage Limit object specifies the amount of data that can be transmitted over this Gate before meeting a volume threshold. This object is OPTIONAL in a Gate-Set and Gate-Info-Ack message. It MUST NOT be used in any other messages. The Volume-Based Usage Limit object MUST conform to the following specification:
+
+|             |           |            |
+|-------------|-----------|------------|
+| Length = 12 | S-Num = 9 | S-Type = 1 |
+| Usage Limit |           |            |
+
+Usage Limit is a 8-byte unsigned integer defined in units of kilobytes. A value of zero indicates no volume limit is imposed. The bytes counted towards the limit are from the byte after the DOCSIS MAC Header HCS to the end of the CRC for all packets transmitted on the Service Flow associated with this Gate.
+
+#### 6.4.2.10 Time-based usage limit
+
+The Time-Based Usage Limit object specifies the amount of time a Gate can remain committed before meeting a time-limit threshold. The Time-Based Usage Limit object MUST conform to the following specification:
+
+|            |            |            |
+|------------|------------|------------|
+| Length = 8 | S-Num = 10 | S-Type = 1 |
+| Time-Limit |            |            |
+
+Time-Limit is a 4-byte unsigned integer defined in units of seconds. This is the limit on the amount of time a Gate can be in a committed state. This object is OPTIONAL in a Gate-Set message. If included in a Gate-Set this object MUST be stored by the CMTS and provided in response to any subsequent Gate queries. While the Application Manager is REQUIRED to delete Gates associated with a media session that has exceeded its Time-Based Usage Limit, the CMTS or Policy Server MAY use this object to police Application Manager enforcement of Time-Based Usage Limits. The Application Manager or Policy Server MAY also query for this object as part of a failure recovery or other mechanism.
+
+A value of zero indicates no time-limit for the associated Gate.
+
+#### 6.4.2.11 Opaque data
+
+The Opaque Data object contains information that a Policy Server or Application Manager MAY store on a CMTS that remains opaque to the CMTS. The opaque data object is OPTIONAL in a Gate-Set message. It MUST NOT be used in any other messages issued by the PDP to the PEP. If the object is present, the CMTS MUST store the Opaque Data locally, and include it in all messages it generates to the Policy Server associated with the Gate.
+
+If the Opaque Data object is included in a Gate-Set message from the Application Manager to a Policy Server, the Policy Server MUST forward this object to the CMTS. The length of the Opaque Data is fixed at 8 bytes.
+
+|             |            |            |
+|-------------|------------|------------|
+| Length = 12 | S-Num = 11 | S-Type = 1 |
+| Opaque Data |            |            |
+| -----       |            |            |
+
+#### 6.4.2.12 Gate time info
+
+The Gate Time Info object contains the total amount of time the Gate has been in the Committed and Committed Recovery states. This counter MUST be stopped upon the Gate transitioning out of the Committed or Committed Recovery states to either the Reserved state or Authorized state. If the Gate subsequently transitions back to the Committed state, this counter MUST be restarted where it last stopped, i.e., when transitioning out of the Committed or Committed Recovery states. The Gate Time Info object MUST conform to the following specification:
+
+|                |            |            |
+|----------------|------------|------------|
+| Length = 8     | S-Num = 12 | S-Type = 1 |
+| Time Committed |            |            |
+
+Time Committed is a 4-byte unsigned integer indicating the number of seconds this Gate has been in either the Committed state or the Committed Recovery state.
+
+NOTE – This is intended to be identical to docsQosServiceFlowTimeActive from the QoS MIB [17].
+
+#### 6.4.2.13 Gate usage info
+
+The Gate Usage Info object contains a counter indicating the number of kilobytes transmitted over this Gate. The Gate Usage Info object MUST conform to the following specification:
+
+|             |            |            |
+|-------------|------------|------------|
+| Length = 12 | S-Num = 13 | S-Type = 1 |
+| Octet Count |            |            |
+
+Octet Count is a 4-byte unsigned integer which represents the number of bytes (counted from the DOCSIS MAC Header HCS to the end of the CRC) which have traversed the Service Flow associated with the Gate in units of 1024 bytes.
+
+#### 6.4.2.14 IPCablecom error
+
+The IPCablecom Error object contains information on the type of error that has occurred. The error is generated in response to a Gate Control command and is contained in Gate-Set-Err, Gate-Info-Err and Gate-Delete-Err messages. The IPCablecom Error object MUST conform to the following specification:
+
+|            |               |            |
+|------------|---------------|------------|
+| Length = 8 | S-Num = 14    | S-Type = 1 |
+| Error-Code | Error-Subcode |            |
+
+Error-Code is a 2-byte unsigned integer representing a specific error and MUST be one of the following:
+
+- 1 = Insufficient Resources;
+- 2 = Unknown GateID;
+- 6 = Missing Required Object;
+- 7 = Invalid Object;
+- 8 = Volume-Based Usage Limit Exceeded;
+- 9 = Time-Based Usage Limit Exceeded;
+- 10 = Session Class Limit Exceeded;
+- 11 = Undefined Service Class Name;
+
+- 12 = Incompatible Envelope;
+- 13 = Invalid SubscriberID;
+- 14 = Unauthorized AMID;
+- 15 = Number of Classifiers Not Supported;
+- 127 = Other, Unspecified Error.
+
+Error-Subcode is a 2-byte unsigned integer field used to provide further information about the error. In the case of Error-Codes 6 and 7, this 16-bit field MUST contain, as two 8-bit values the S-Num and S-Type of the object that is missing or in error. The order of the S-Num and S-Type values within the Error-Subcode MUST be the same as in the original message. In cases where multiple valid alternatives exist for the S-Type of a missing object, this portion of the Error-Subcode MUST be set to zero. In the case of Error-Code 15, the Error-Subcode field MUST contain the number of Classifiers supported per Gate.
+
+Error-Codes 8, 9 and 10 are generated as a result of a Policy Request failing to meet the requirements of a Policy Server's authorization. When the Application Manager issues a Gate-Set message with a volume or time-based limit to the Policy Server, the Policy Server MAY reject the request based on policy rules installed on the Policy Server. For example, such a policy rule may state that if a volume limit request exceeds a maximum value, the Policy Server must reject the request.
+
+#### 6.4.2.15 Gate state
+
+The information in the Gate State object reflects the current state of the Gate. The CMTS MUST include the Gate State object in any unsolicited messages that it sends to the Policy Server. The Policy Server may use this information to report state to the Application Manager, or for enforcing complex rules that might require state knowledge of the Gate.
+
+Typically, the Policy Server is aware of state transitions since it usually provides the stimulus for these transitions to the CMTS, but in some cases the Gate may transition locally on the CMTS without the Policy Server's involvement. In these cases, the CMTS MUST report the state transition to the Policy Server via unsolicited Gate-Report-State messages. When issuing Gate-Report-State messages, the PEP MUST make sure the Solicited Flag in the COPS message header is cleared, and the Report Type in the header is set to Accounting. The Gate State object MUST conform to the following specification:
+
+|            |            |            |
+|------------|------------|------------|
+| Length = 8 | S-Num = 15 | S-Type = 1 |
+| State      | Reason     |            |
+
+State is a 2-byte unsigned integer field which MUST indicate one of the following states:
+
+- 1 = Idle/Closed;
+- 2 = Authorized;
+- 3 = Reserved;
+- 4 = Committed;
+- 5 = Committed-Recovery.
+
+Reason is a 2-byte unsigned integer field which MUST indicate one of the following reasons for this update:
+
+- 1 = Close initiated by CMTS due to reservation reassignment;
+- 2 = Close initiated by CMTS due to lack of DOCSIS MAC-layer responses;
+- 3 = Close initiated by CMTS due to timer T1 expiration;
+
+- 4 = Close initiated by CMTS due to timer T2 expiration;
+- 5 = Inactivity timer expired due to Service Flow inactivity (timer T3 expiration);
+- 6 = Close initiated by CMTS due to lack of Reservation Maintenance;
+- 7 = Gate state unchanged, but volume limit reached;
+- 8 = Close initiated by CMTS due to timer T4 expiration;
+- 9 = Gate state unchanged, but timer T2 expiration caused reservation reduction;
+- 65535 = Other.
+
+#### 6.4.2.16 Version info
+
+The Version Info object is used to enable Multimedia applications to adapt their interactions with other devices so that interoperability can be achieved between products supporting different protocol versions. Both the Major Version Number and the Minor Version Number are 2 byte unsigned integers. Both the PDP and the PEP must include this object as specified in 6.5.1.
+
+|                      |                      |            |
+|----------------------|----------------------|------------|
+| Length = 8           | S-Num = 16           | S-Type = 1 |
+| Major Version Number | Minor Version Number |            |
+
+### 6.4.3 Gate control messages
+
+There are two separate profiles for Gate Control messages: one for messages exchanged between the Application Manager and the Policy Server, and one for messages between the Policy Server and the CMTS. While similar, these two profiles do exhibit some minor differences.
+
+The following statements describe the PCMM message formats, covering both COPS and PCMM objects. These statements specify the content of messages, but do not imply a particular ordering of objects within each message. In particular, any ordering of PCMM objects MUST be accepted as valid (and may be generated), and the order of COPS objects MUST be as specified in RFC 2748. Note that since PCMM objects only exist inside COPS objects, the distinction between these two sets is clear. This containment model also ensures that there are no issues with the relative order of COPS and PCMM objects.
+
+#### 6.4.3.1 Profile for application manager to policy server interface
+
+Messages that perform gate control between the Application Manager and Policy Server are defined and MUST be formatted as follows.
+
+Note that messages from the Application Manager to Policy Server MUST be formatted as COPS Decision messages, and messages from Policy Server to Application Manager MUST be formatted as COPS Report-State messages.
+
+```
+
+<Client Open> = <COPS Common Header> <COPS PEPID> <ClientSI Info>
+<ClientSI Info> = <COPS Client SI Header> <MM Version Info>
+<Gate Control Command> = <COPS Common Header> <Client Handle> <Context>
+                    <Decision Flags> <ClientSI Data>
+<ClientSI Data> = <Gate-Set> | <Gate-Info> | <Gate-Delete>
+<Gate Control Response> = <COPS Common Header> <Client Handle> <Report Type>
+                    <ClientSI Object>
+<ClientSI Object> = <Gate-Set-Ack> | <Gate-Set-Err> | <Gate-Info-Ack>
+                    | <Gate-Info-Err> | <Gate-Delete-Ack> | <Gate-Delete-Err>
+                    | <Gate-State-Report>
+<Gate-Set> = <Decision Header> <TransactionID> <AMID> <SubscriberID> [<GateID>]
+
+```
+
+```
+
+<GateSpec> <Traffic Profile> <Classifier> [<Classifier>]
+[<Event Generation Info>]
+[<Volume-Based Usage Limit>] [ <Time-Based Usage Limit> ] [<Opaque
+Data>]
+<Gate-Set-Ack> = <ClientSI Header> <TransactionID> <AMID> <SubscriberID>
+    <GateID>
+    [<Opaque Data>]
+<Gate-Set-Err> = <ClientSI Header> <TransactionID> <AMID> <SubscriberID>
+    <IPCablecom Error> [<Opaque Data>]
+<Gate-Info> = <Decision Header> <TransactionID> <AMID> <SubscriberID><GateID>
+<Gate-Info-Ack> = <ClientSI Header> <TransactionID> <AMID> <SubscriberID>
+    <GateID>
+    [<Event Generation Info>] <GateSpec> <GateState> <Classifier>
+    <Classifier> <Traffic Profile> <Gate Time Info>
+    <Gate Usage Info> [<Volume-Based Usage Limit>]
+    [<Time-Based Usage Limit>] [<Opaque Data>]
+<Gate-Info-Err> = <ClientSI Header> <TransactionID> <AMID> <GateID>
+    <IPCablecomErr>
+    [<Opaque Data>]
+<Gate-Delete> = <Decision Header> <TransactionID> <AMID> <SubscriberID> <GateID>
+<Gate-Delete-Ack> = <ClientSI Header> <TransactionID> <AMID> <GateID> [<Opaque
+Data>]
+<Gate-Delete-Err> = <ClientSI Header> <TransactionID> <AMID> <GateID>
+    <IPCablecom Error> [<Opaque Data>]
+<Gate-Report-State> = <ClientSI Header> <TransactionID> <AMID> <SubscriberID>
+    <GateID> <GateState>
+    <Gate Time Info> <Gate Usage Info> [<Opaque Data>]
+
+```
+
+#### 6.4.3.2 Profile for policy server to CMTS interface
+
+Messages that perform Gate Control between the Policy Server and CMTS are defined and MUST be formatted as follows.
+
+Note that messages from Policy Server to CMTS MUST be formatted as COPS Decision messages, and messages from CMTS to Policy Server MUST be formatted as COPS Report-State messages.
+
+```
+
+<Client Open> = <COPS Common Header> <COPS PEPID> <ClientSI Info>
+<ClientSI Info> = <COPS Client SI Header> <MM Version Info>
+<Gate Control Command> = <COPS Common Header> <Client Handle> <Context>
+    <Decision Flags> <ClientSI Data>
+<ClientSI Data> = <Gate-Set> | <Gate-Info> | <Gate-Delete>
+<Gate Control Response> = <COPS Common Header> <Client Handle> <Report Type>
+    <ClientSI Object>
+<ClientSI Object> = <Gate-Set-Ack> | <Gate-Set-Err> | <Gate-Info-Ack>
+    | <Gate-Info-Err> |
+    <Gate-Delete-Ack> | <Gate-Delete-Err> | <Gate-Report-State>
+<Gate-Set> = <Decision Header> <TransactionID> <AMID> <SubscriberID> [<GateID>]
+    <GateSpec> <Traffic Profile> <Classifier> [<Classifier>] [<Event Generation
+    Info>]
+
+```
+
+```
+
+    [<Volume-Based Usage Limit>] [<Time-Based Usage Limit>] [<Opaque Data>]
+<Gate-Set-Ack> = <ClientSI Header> <TransactionID> <AMID> <SubscriberID>
+    <GateID>
+    [<Opaque Data>]
+<Gate-Set-Err> = <ClientSI Header> <TransactionID> <AMID> <SubscriberID>
+    <IPCablecom Error> [<Opaque Data>]
+<Gate-Info> = <Decision Header> <TransactionID> <AMID> <SubscriberID> <GateID>
+<Gate-Info-Ack> = <ClientSI Header> <TransactionID> <AMID> <SubscriberID>
+    <GateID>
+    [<Event Generation Info>] <Gate-Spec> <Classifier> <Classifier>
+    <Traffic Profile> <Gate Time Info> <Gate Usage Info> [<Volume-Based Usage Limit>]
+    [<Time-Based Usage Limit>] [<Opaque Data>] <Gate State>
+<Gate-Info-Err> = <ClientSI Header> <TransactionID> <AMID> <GateID>
+    <IPCablecomErr>
+    [<Opaque Data>]
+<Gate-Delete> = <Decision Header> <TransactionID> <AMID> <SubscriberID> <GateID>
+<Gate-Delete-Ack> = <ClientSI Header> <TransactionID> <AMID> <GateID> [<Opaque Data>]
+<Gate-Delete-Err> = <ClientSI Header> <TransactionID> <AMID> <GateID>
+    <IPCablecom Error> [<Opaque Data>]
+<Gate-Report-State> = <ClientSI Header> <TransactionID> <AMID> <SubscriberID>
+    <GateID> <GateState>
+<Gate Time Info> <Gate Usage Info> [<Opaque Data>]
+
+```
+
+There are three basic Gate Control command messages: Gate-Set, Gate-Info, and Gate-Delete. These messages are embedded in the Client-Specific Decision Data in a COPS Decision message. For Gate Control command messages, the Context object (C-Num = 2, C-Type = 1) in the COPS Decision message MUST have the R-Type (Request Type Flag) value set to 0x08 (Configuration Request) and the M-Type set to zero. The Command-Code field in the mandatory Decision-Flags object (C-Num = 6, C-Type = 1) MUST be set to 1 (Install Configuration). Other values MUST cause the CMTS to generate a Report-State message indicating failure. The flags subfield MAY be set to any value and MUST be ignored by the PEP. The Gate Command Type field in the TransactionID object distinguishes the type of command being issued.
+
+There are seven Gate Control response messages: Gate-Set-Ack, Gate-Set-Err, Gate-Info-Ack, Gate-Info-Err, Gate-Delete-Ack, Gate-Delete-Err, and Gate-Report-State. The first six Gate Control response messages are solicited responses to Gate Control command messages. The seventh, Gate-Report-State, is an unsolicited response to the PS from the CMTS to inform of a state change.
+
+These messages are embedded in the Client-Specific Information Object in COPS Report-State messages. The Report-Type object (C-Num = 12, C-Type = 1) included in the COPS Report-State message for Gate Control responses MUST have the Report-Type field set to 1 (Success) or 2 (Failure) depending on the outcome of the Gate Control command. Report-State messages in response to a Gate Control command MUST have the solicited message flag bit set in the COPS header. The Gate Command Type field in the TransactionID object distinguishes the type of response being issued.
+
+The CMTS generates the Gate-Report-State message when there is a state transition on the Gate that is not due to a Decision message, or when some policy limit has been reached. For the
+
+Gate-Report-State message, the Report-Type field MUST be set to 3 (Accounting), and the solicited flag field in the common header MUST be cleared.
+
+If an object that is received in a Gate Control message contains an S-Num or S-Type that is not recognized, that object MUST be ignored. The presence of such an object within a Gate Control message MUST NOT be treated as an error provided that after such parameter is dropped, all required objects are present in the message.
+
+## 6.5 Gate control protocol operation
+
+### 6.5.1 Initialization sequence
+
+When a PEP (Policy Server or CMTS) boots, it MUST listen for incoming COPS connections on the IANA-assigned TCP port number 3918. Any Application Manager or Policy Server (PDP) with a need to contact a PEP MUST initiate a TCP connection to the PEP on that port. It is expected that multiple Application Managers will establish COPS connections with multiple Policy Servers, and multiple Policy Servers will establish COPS connections with multiple CMTSs. When the TCP connection between the PEP and the PDP is established, the PEP MUST send information about itself to the PDP in the form of a Client-Open message. This message MUST include the Multimedia Version Info object, which will inform the PDP of the currently supported Multimedia protocol version used on the PEP.
+
+Upon successful receipt of the Client-Open message, the PDP MUST send a Client-Accept message if the protocol version specified in the Version Info object is supported. This message MUST include the Keep-Alive-Timer object, which tells the PEP the maximum interval between Keep-Alive messages.
+
+If the protocol version supplied by the PEP is not supported, the PDP MUST send a Client-Close message with a COPS Error Object specifying error code 4 (Unable to process). After sending the Client-Close, the PDP MUST retain the TCP connection and security association with the PEP so that the PEP can reattempt the COPS initialization without reestablishing the TCP connection and security association. After receiving a Client-Close message from the PDP, which includes a COPS Error Object specifying error code 4, the PEP MAY reattempt initialization of the COPS connecting by sending another Client-Open message with another version number in the Version Info Object. This process MAY continue until the PEP has either received a Client-Accept message from the PDP, or has exhausted all available protocol versions. Once the PEP has tried all the protocol versions it supports, the PEP MUST send a Client-Open message with a Major Version Number of 0 and a Minor Version Number of 0 to indicate that it has unsuccessfully completed the version negotiation process. The PDP MUST then send a Client-Close message to the PEP to acknowledge that protocol negotiation has failed. On receipt of the Client-Close, the PEP MUST close the TCP connection. At this point, the PDP MAY periodically attempt to re-establish the connection.
+
+Devices compliant with this specification MUST use a version of 1.0, i.e., a Version Info Object with a Major Version Number of 1 and a Minor Version Number of 0.
+
+Upon successful receipt of the Client-Accept message, the PEP MUST send a Request message, including the Client-Handle and Context objects. The Context object (C-Num = 2, C-Type = 1) MUST have the R-Type (Request Type Flag) value set to 0x08 (Configuration Request) and M-Type set to zero. The Client-Handle object contains a value that MUST be chosen by the PEP. The only requirement imposed on this value is that a PEP MUST NOT use the same value for two different Requests on a single TCP connection. This completes the initialization sequence, which is visually depicted below.
+
+![Sequence diagram for COPS connection establishment between PDP and PEP.](7e14467740b2570a44379b347a697921_img.jpg)
+
+```
+
+sequenceDiagram
+    participant PDP
+    participant PEP
+    Note right of PEP: J.179_F05
+    PDP->>PEP: TCP connection to multimedia port
+    PEP-->>PDP: COPS OPN
+    PDP->>PEP: COPS CAT
+    PDP->>PEP: COPS REQ
+    PEP-->>PDP: COPS connection is initialized
+  
+```
+
+The diagram illustrates the sequence of messages for COPS connection establishment. It starts with a solid arrow from PDP to PEP labeled "TCP connection to multimedia port". This is followed by a dashed return arrow from PEP to PDP labeled "COPS OPN". Then, a solid arrow from PDP to PEP labeled "COPS CAT", followed by another solid arrow from PDP to PEP labeled "COPS REQ". Finally, a dashed return arrow from PEP to PDP labeled "COPS connection is initialized". The diagram is labeled "J.179\_F05" at the bottom right.
+
+Sequence diagram for COPS connection establishment between PDP and PEP.
+
+**Figure 5/J.179 – COPS connection establishment**
+
+Periodically, the PEP MUST send a COPS Keep-Alive (KA) message to the PDP. Upon receipt of the COPS KA message, the PDP MUST echo a COPS KA message back to the PEP. This transaction is shown below and is fully documented in [7]. The PEP MUST send a Keep-Alive message at least as often as specified in the Keep-Alive-Timer object returned in the Client-Accept message. The Keep-Alive message MUST be sent with Client-Type set to zero and the solicited flag cleared.
+
+![Sequence diagram for COPS keep-alive exchange between PDP and PEP.](56a5265d174ce056c1dbe5e7a60839fc_img.jpg)
+
+```
+
+sequenceDiagram
+    participant PDP
+    participant PEP
+    Note right of PEP: J.179_F06
+    PEP->>PDP: COPS KA
+    PDP-->>PEP: COPS KA
+  
+```
+
+The diagram illustrates the sequence of messages for COPS keep-alive exchange. It starts with a solid arrow from PEP to PDP labeled "COPS KA". This is followed by a dashed return arrow from PDP to PEP labeled "COPS KA". The diagram is labeled "J.179\_F06" at the bottom right.
+
+Sequence diagram for COPS keep-alive exchange between PDP and PEP.
+
+**Figure 6/J.179 – COPS keep-alive exchange**
+
+### 6.5.2 Operation sequence
+
+The protocol between the PDP and PEP is used for purposes of resource control and resource allocation policy. The Application Manager requests policy decisions from the Policy Server, and the Policy Server authorizes the requests and install them on the CMTS for enforcement through the use of Gates.
+
+Messages that MAY be initiated by the Application Manager and Policy Server include Gate-Set, Gate-Info and Gate-Delete. The CMTS MAY initiate Gate-Report-State messages. The procedures for these messages are described in the following clauses. All messages from the PDP to the PEP MUST be sent using Client-Specific objects within the Decision object of a COPS Decision message. Solicited responses from the PEP MUST be sent as a Report-State message with Client-Specific objects in the ClientSI object, and the solicited flag MUST be set. Gate-Report-State messages from the CMTS MUST be sent as unsolicited Report-State messages via Client-Specific objects in the ClientSI object.
+
+The Decision messages and Report-State messages MUST contain the same Client-Handle as provided in the initial Request sent by the CMTS when the COPS connection was initiated.
+
+Gate-Set initializes and modifies all the policy and traffic parameters for the Gate and establishes billing information. Gate-Set may also be used to control and update the state of a Gate on the CMTS.
+
+Gate-Info is a mechanism by which the Policy Server may query all the current state and parameter settings of an existing Gate.
+
+Gate-Delete allows a Policy Server to delete a specific Gate and any associated Service Flow.
+
+Gate-Report-State allows the CMTS to inform the Policy Server that the Gate has transitioned into a new state. Gate-Report-State messages MUST be generated when the state transition happens asynchronously (i.e., not as a response to a Gate-Set message). Gate-Report-State messages MUST NOT be generated when the state transition happens synchronously.
+
+The PEP MUST periodically send a Keep-Alive (KA) message to the PDP to facilitate the detection of TCP connection failures. The PDP MUST keep track of when KAs are received. If the PEP has not received a KA from the PDP in the time interval specified in [7] or the PDP has not received an error indication from the TCP connection, then the PDP MUST tear down the TCP connection and attempt to re-establish the TCP connection.
+
+The following rules are used to route Gate Control messages through the IPCablecom Multimedia framework. In particular, provisions are provided for passing Gate Control messages forward (i.e., AM-to-PS-to-CMTS) and backward (i.e., CMTS-to-PS-to-AM) through a complex layered network in which multiple instances of each element are interacting with elements in the adjoining layer(s).
+
+As described in 6.4.3.1, each Gate Control request that is initiated by an AM (i.e., Gate-Set, Gate-Info, and Gate-Delete) MUST include (in addition to other mandatory objects) both AMID and SubscriberID objects.
+
+Upon receipt of a Gate Control message from an AM, a PS will apply any provisioned policy rules and determine whether to admit or reject the request. If the request is successfully admitted, the PS MUST route the message to the appropriate CMTS based on the SubscriberID included in the message. This SubscriberID-to-CMTS mapping MAY be performed dynamically based on a query to the OSS infrastructure or MAY reflect pre-provisioned routing information related to the range(s) of IP subnets that are associated with each CMTS.
+
+If a Gate Control request is rejected by the PS, an error response MUST be returned to the issuing AM over the connection on which the original request was received. If a failure is detected on this connection between the time that a request is received and the response is delivered, the PS MUST discard the response.
+
+Upon receiving a Gate Control message from a PS, a CMTS will execute the requested operation. If this operation is successful involving either a Gate-Set or Gate-Info operation, the CMTS MUST record the AMID and SubscriberID included in the message and maintain an association with the referenced Gate. This information must be used to ensure that only the AM which originally created the Gate is allowed to query or modify it. Any Gate Control messages that reference a Gate but which contain an AMID other than the one associated with the Gate MUST be rejected by the CMTS with error "Unauthorized AMID". Finally, Gate-Report-State messages MUST be delivered to the PS element, identified through its IP address, that originally created the Gate. If a connection to this PS is not available, then the CMTS MUST suppress Gate-Report-State messages.
+
+When a PS receives a Gate-Report-State message from a CMTS, the PS MUST forward this message to the AM associated with the AMID included in the message. In order to maintain a level of abstraction between non-adjacent layers and to hide information related to network topology from the AM layer, the PS MUST NOT include information directly identifying a particular CMTS to the AM layer.
+
+### 6.5.3 Procedures for validating resource envelopes
+
+The set of data service flow characteristics that are important for the purposes of providing enhanced Quality of Service is known as the envelope. An IPCablecom Multimedia Gate contains up to three envelopes: one that indicates the Authorized resources, one that indicates the Reserved resources, and one that indicates the Committed resources for the service flow corresponding to the Gate. At any one point in time, the Committed envelope MUST fit within the Reserved Envelope which MUST fit within the Authorized envelope.
+
+When a CMTS receives a Gate-Set message, it MUST validate the relation between the Committed, Reserved, and Authorized envelopes of the Gate. If the envelope relation is invalid, the CMTS MUST reply with a Gate-Set-Err message with an IPCablecom Error-Code of "Incompatible Envelope".
+
+The CMTS MUST also perform admission control whenever a change (including an addition) of the reserved envelope is requested. Admission control is the process of assigning resources for the flow corresponding to the gate. If the resources cannot be assigned, the CMTS MUST reply with a Gate-Set-Err message with an IPCablecom Error-Code of "Insufficient Resources".
+
+#### 6.5.3.1 Flow spec
+
+In Table 2, The second column indicates the operation that should be used to compare a parameter of A's envelope to a corresponding parameter in B's envelope. In other words, envelope A fits within envelope B if each of A's parameters meets the criteria specified in the table.
+
+**Table 2/J.179 – Envelope comparison rules**
+
+| Parameter                | A {OP} B |
+|--------------------------|----------|
+| Token Bucket Rate [r]    | $\leq$   |
+| Token Bucket Size [b]    | $\leq$   |
+| Peak Data Rate [p]       | $\leq$   |
+| Minimum Policed Unit [m] | $\geq$   |
+| Maximum Packet Size [M]  | $\leq$   |
+| Rate [R]                 | $\leq$   |
+| Slack Term [S]           | $\geq$   |
+
+#### 6.5.3.2 DOCSIS service class name
+
+For traffic profiles in the form of a Service Class Name, the Service Class Name string MUST exactly match the pre-existing Service Class Name on the CMTS. No envelope comparison is necessary as all three envelopes must share the same envelope parameters.
+
+#### 6.5.3.3 DOCSIS service flow parameters
+
+##### 6.5.3.3.1 Upstream encodings
+
+In Table 3, the second column indicates the operation that should be used to compare a parameter of A's envelope to a corresponding parameter in B's envelope. In other words, envelope A fits within envelope B if each of A's parameters meets the criteria specified in the table.
+
+**Table 3/J.179 – Upstream envelope comparison**
+
+| <b>Parameter</b>                                                    | <b>A {OP} B</b>                |
+|---------------------------------------------------------------------|--------------------------------|
+| Traffic Priority (BE & NRTPS)                                       | $\leq$                         |
+| Request Transmission Policy (all)                                   | $=$                            |
+| Maximum Sustained Traffic Rate (BE, NRTPS, RTPS)                    | $\leq$                         |
+| Maximum Traffic Burst (BE, NRTPS, RTPS)                             | $\leq$                         |
+| Minimum Reserved Traffic Rate (BE, NRTPS, RTPS)                     | $\leq$                         |
+| Assumed Minimum Reserved Traffic Rate Packet Size (BE, NRTPS, RTPS) | $\geq$                         |
+| Nominal Polling Interval (NRTPS, RTPS, UGS/AD)                      | See interval description below |
+| Tolerated Poll Jitter (RTPS, UGS/AD)                                | $\geq$                         |
+| Unsolicited Grant Size (UGS & UGS/AD)                               | $\leq$                         |
+| Grants per Interval (UGS & UGS/AD)                                  | $\leq$                         |
+| Nominal Grant Interval (UGS & UGS/AD)                               | See interval description below |
+| Tolerated Grant Jitter (UGS & UGS/AD)                               | $\geq$                         |
+
+Intervals – A is a subset of B if the parameter in A is an integer multiple of the same parameter in B.
+
+##### 6.5.3.3.2 Downstream encodings
+
+In Table 4, the second column indicates the operation that should be used to compare a parameter of A's envelope to a corresponding parameter in B's envelope. In other words, envelope A fits within envelope B if each of A's parameters meets the criteria specified in the table.
+
+**Table 4/J.179 – Downstream envelope comparison**
+
+| <b>Parameter</b>                                  | <b>A {OP} B</b> |
+|---------------------------------------------------|-----------------|
+| Traffic Priority                                  | $\leq$          |
+| Maximum Sustained Traffic Rate                    | $\leq$          |
+| Maximum Traffic Burst                             | $\leq$          |
+| Minimum Reserved Traffic Rate                     | $\leq$          |
+| Assumed Minimum Reserved Traffic Rate Packet Size | $\geq$          |
+| Maximum Downstream Latency                        | $\geq$          |
+
+### 6.5.4 Procedures for authorizing resources through a gate
+
+The Gate-Set message MAY be sent by the PDP to the PEP to initialize or modify the operational parameters of a Gates. Figure 7 provides an example of Gate-Set signalling.
+
+NOTE – As an example, the "Start Session" message can be used to indicate to the Client that the resources have been authorized.
+
+![Sequence diagram showing the signalling of gate-set between a Client, PEP, and PDP. The Client sends a GATE-SET message to the PDP. The PDP responds with a GATE-SET-ACK to the PEP. The PEP then sends a Start Session message to the Client. The diagram is labeled J.179_F07.](fd8f5da2b60cdca94896f3cde8ee81f0_img.jpg)
+
+```
+
+sequenceDiagram
+    participant Client
+    participant PEP
+    participant PDP
+    Note right of PDP: J.179_F07
+    PDP->>PEP: GATE-SET
+    PEP->>PDP: GATE-SET-ACK
+    PEP->>Client: Start Session
+  
+```
+
+Sequence diagram showing the signalling of gate-set between a Client, PEP, and PDP. The Client sends a GATE-SET message to the PDP. The PDP responds with a GATE-SET-ACK to the PEP. The PEP then sends a Start Session message to the Client. The diagram is labeled J.179\_F07.
+
+**Figure 7/J.179 – Sample signalling of gate-set**
+
+If a GateID object is present in the Gate-Set message, then the request is to modify an existing Gate. If the GateID object is missing from the Gate-Set message, then it is a request to allocate a new Gate. The Gate-Set message MUST contain exactly one GateSpec object, describing one upstream or downstream Gate.
+
+The Gate-Set message also contains the SubscriberID. The CMTS MUST use this IP address (i.e., the SubscriberID) to determine the servicing CM and MUST use the MAC address of the CM for subsequent MAC-layer messaging.
+
+The PEP MUST respond to a Gate-Set message with either a Gate-Set-Ack, indicating success, or a Gate-Set-Err, indicating failure. The TransactionID in the response MUST match the TransactionID in the request. Errors in allocating or authorizing Gates MUST be reported by a Gate-Set-Err response. Refer to 6.4.2.14.
+
+In Scenario 1, the Policy Server MAY specify the Authorized, Reserved and Committed Envelopes via a Traffic Profile sent in the Gate-Set message. It MAY simultaneously instruct the CMTS to authorize, reserve and commit resources.
+
+Upon the receipt of a Gate-Set, the CMTS must first meet the requirements specified in 6.5.3 and then perform the requested actions. Upon successful completion of the actions requested in the Gate-Set (e.g., creation of a DOCSIS Service Flow), the CMTS MUST respond with a Gate-Set-Ack. The CMTS MUST NOT respond with a Gate-Set-Ack until it has completed sufficient steps to ensure that any subsequent requests to Admit or Commit the Gate will not fail due to a lack of resources.
+
+A CMTS MAY perform complex authorization based not only on the requested QoS and the Gate's authorized FlowSpec, but also based on the SessionClassID specified in the GateSpec. The CMTS MAY have provisioned policies that define the amount of resources allocated exclusively to the particular Session Class, as well as 'borrow' and 'preemption' rules that apply to the use of the resources. The specifics of these types of policies and rules on the CMTS are out of scope of this Recommendation.
+
+Upon receipt of a Gate-Set-Ack or Gate-Set-Err from a CMTS, the Policy Server MUST forward the message to the Application Manager corresponding to the AMID in the Gate-Set-Ack. The Policy Server MUST NOT transmit a Gate-Set-Ack to an Application Manager prior to receiving a Gate-Set-Ack from the CMTS. If the Application Manager requests a service that does not pass the Policy Server's policy checks, however, the Policy Server MUST NOT send the Gate-Set to the CMTS and MUST send a Gate-Set-Err to the Application Manager with the appropriate errors set.
+
+### 6.5.5 Procedures for querying a gate
+
+When a Policy Server or Application Manager wishes to query the current parameter settings of a Gate, it sends to the CMTS a Gate-Info message. The CMTS MUST respond to a Gate-Info message with either a Gate-Info-Ack, indicating success, or a Gate-Info-Err, indicating failure. A
+
+Gate-Info-Ack MUST contain information on the Gate associated with the GateID in the Gate-Info message. If the Gate being queried has an existing Volume-Based and/or Time-Based Usage Limit, then the CMTS MUST include these objects in the Gate-Info-Ack. A PS or AM can utilize this information to recover Gate state information from the CMTS for policing, error recovery or other purpose. The TransactionID in the response MUST match the TransactionID in the request.
+
+Errors in querying gates MUST be reported by a Gate-Info-Err response. The Error object in a Gate-Info-Err message MUST contain one of the following Error-Codes:
+
+2 = Unknown GateID;
+
+127 = Other, Unspecified Error.
+
+### **6.5.6 Procedures for modifying a gate**
+
+To modify the Traffic Profile associated with an existing Gate, an Application Manager MAY send a Gate-Set message with the GateID of the Gate to be modified and the new Traffic Profile. If the Gate-Set fails the Policy Server's checks, the Policy Server MUST send a Gate-Set-Err to the Application Manager and MUST NOT send a Gate-Set to the CMTS. However, if the Gate-Set passes the Policy Server's policy checks, the Policy Server MUST send the Gate-Set to the CMTS. The TransactionID in the Policy Server Gate-Set MUST match the TransactionID in the Application Manager Gate-Set.
+
+Upon receipt of a Gate-Set, the CMTS must first meet the requirements specified in 6.5.3 and then perform the requested actions. As with the creation of a new Gate, upon successful completion of the actions requested in the Gate-Set (e.g., modification of a DOCSIS service flow), the CMTS MUST respond with a Gate-Set-Ack. The CMTS MUST NOT respond with a Gate-Set-Ack until it has completed a sufficient number of steps to ensure that any subsequent requests to Admit or Commit the Gate will not fail due to lack of resources.
+
+Upon receipt of a Gate-Set-Ack or Gate-Set-Err from the CMTS, the Policy Server MUST forward the response to the Application Manager.
+
+To modify the Usage Limits associated with an existing Gate, an Application Manager MAY send a Gate-Set message with the GateID of the Gate to be modified. If the Traffic Profile in the Gate-Set is different from the Traffic Profile currently associated with the Gate, then the previous rules apply. In either case, if the Time-Based Usage Limit or Volume-Based Usage Limit of the flow is present, then the existing limits associated with this/these parameter(s) MUST be replaced with the new parameter(s) and any existing counters or timers MUST be reset. However, the absence of these parameters from a Gate-Set message indicates that even if the Traffic Profile for the Gate is being modified, the existing Time-Based or Volume-Based Usage Limit(s) of the Gate still apply. If these parameters are not present in a Gate-Set message, the existing limits MUST be maintained and their associated counters/timers MUST continue from their current value without resetting.
+
+### **6.5.7 Procedures for supporting usage limits**
+
+The Application Manager, Policy Server and CMTS all have a role in enforcing Usage Limits. There are subtle differences between Time-Based and Volume-Based Limits so each of these is described separately.
+
+#### **6.5.7.1 Procedures upon reaching a volume-based usage limit**
+
+Since the CMTS is the only trusted IPCablecom Multimedia device in the packet path, it is the only device capable of accurately tracking the usage of individual Gates. Thus, the CMTS MUST track the usage of all Gates regardless of whether or not they have an associated Volume-Based Usage Limit. The CMTS MUST report the amount of data transferred via a Gate in all Gate-Info-Ack and all Gate-Report-State messages.
+
+If the Gate has an associated Volume-Based Usage Limit when the amount of data that has traversed the Gate equals the Volume-Based Usage Limit, the CMTS MUST send a Gate-Report-State message with the Solicited bit set to 0. The Gate-State-Report message MUST include a Gate State object with the Reason set to 7 (Gate state unchanged, but volume limit reached). Upon receipt of a Gate-Report-State message, the behaviour of a PDP depends upon its role; a Policy Server MUST either forward the Gate-Report-State message to the Application Manager or handle the report itself. The Policy Server SHOULD only handle the report if it caused the report to be generated by modifying the original gate set. In other words, the Policy Server's actions should be transparent to the Application Manager. The Application Manager MUST handle received reports. A PDP handles a Gate-Report-State message with the Reason set to 7, by performing one of the following actions:
+
+- Send a Gate-Set message with a new Volume-Based Usage Limit object, which the CMTS must use to 'restart' accounting for this Gate;
+- Send a Gate-Set message with a Volume-Based Usage Limit set to 0 to disable the feature and allow the CMTS to continue giving service to the session;
+- Close the Gate by issuing a Gate-Delete command.
+
+#### 6.5.7.2 Procedures upon reaching a time-based usage limit
+
+While it is a desirable design goal to keep the Volume-Based and Time-Based Usage Limit procedures as similar as possible, the number of CMTS interrupts required to support enforcement of Time-Based Usage Limits by the CMTS makes this approach impossible. Thus, the Application Manager MUST enforce the Time-Based Usage Limit of the Gate. Upon receiving the Gate-Set-Ack for a Gate with a Time-Based Usage Limit, the AM MUST start an application timer. When the application timer is equal to the Time-Based Usage Limit, the Application Manager MUST respond by performing one of the following actions:
+
+- Send a Gate-Set message with a new Time-Based Usage Limit object and reset its application timer;
+- Send a Gate-Set message with a Time-Based Usage Limit set to 0 to disable the feature;
+- Close the Gate by issuing a Gate-Delete command.
+
+NOTE – In some ways it makes more sense for the Application Manager to enforce Usage Limits, since the Time-Based Usage Limit and Volume-Based Usage Limit are a reflection of the service being offered and are the responsibility of the Service Control Domain. It is really the Volume-Based Usage Limit procedure which is unusual, but the CMTS is the only device that can accurately enforce this limit.
+
+#### 6.5.7.3 Resource and error recovery
+
+While it is required that the Application Manager perform one of several actions when a Gate's Usage Limit has been reached, there is always the possibility that the Application Manager will not respond appropriately. In this case, the RKS will still be recording the usage of this Gate so this activity will still be billable but, in some instances, it may be useful to recover the resources that are being used 'illegally' by the Application Manager. A Policy Server MAY glean the fact that the Volume-Based or Time-Based Usage Limit of a Gate has been exceeded based on the messages it is proxying between the AM and CMTS. Using the 'gleaning' technique implies that the Policy Server is stateful, but a Policy Server that is not stateful can still recover resources via a second technique described below.
+
+Alternatively, a Policy Server MAY occasionally query the CMTS with a Gate-Info message. The response will contain any associated Volume-Based Usage Limit and Gate Usage Info (or Time-Based Usage Limit and Gate Time Info). The Policy Server can then compare these values. Regardless of how a Policy Server gains the knowledge that a Gate is over-limit, it MAY issue a Gate-Delete for over-limit Gates. Upon receipt of the Gate-Set-Ack (or Gate-Set-Err) from the CMTS, the Policy Server MUST send the message to the Application Manager.
+
+Similarly, while not required to recover resources from over-limit Gates, a CMTS MAY perform the same comparisons itself and MAY delete over-limit Gates. Additional requirements for this scenario are described in 6.5.8.
+
+#### **6.5.7.4 Tracking time-based and volume-based usage limits**
+
+IPCablecom Multimedia Gates can be committed and uncommitted multiple times (to support, for example, a 'pause' function on a game or streaming media). Since a subscriber cannot transmit/receive data while the Gate is not in a committed state, these periods should not be counted against them. For Volume-Based Limits, this requirement has no effect – there are no packets that might be over-counted since no packets can be sent if a Gate is not committed. However, for Time-Based Usage Limits the CMTS MUST stop its Gate Time Info timer when the Gate is not in either the Committed State or the Committed Recovery State. If the Gate is re-Committed without changes to the Time-Based Limit, the Gate Time Info timer MUST be restarted from its stopped count. If changes are made to the Time-Based Limit, the Gate Time Info timer MUST be reset to 0 and restarted when the Gate is re-committed.
+
+NOTE – The Application Manager is required to maintain a timer independent of the CMTS timer to enforce the Time-Based Usage Limit. Since this timer is separated from the CMTS itself, messaging delays could cause discrepancies between these two timers. For applications that require a high-degree of time accuracy, the AM MAY query the CMTS for its Gate Time Info object after it moves a Gate into or out of a committed state.
+
+### **6.5.8 Procedures for deleting a gate**
+
+Normally, when a Multimedia session ends, the Application Manager tells the Policy Server that the session has ended, and the Policy Server in turn instructs the CMTS to remove the Gate via a Gate-Delete message. The CMTS MUST respond to a Gate-Delete message with a Gate-Delete-Ack, indicating success, or a Gate-Delete-Err, indicating failure. The TransactionID in the response MUST match the TransactionID in the request.
+
+Errors in deleting Gates MUST be reported by a Gate-Delete-Err response. The Error object MUST contain one of the following Error-Codes:
+
+2 = Unknown GateID;
+
+127 = Other, Unspecified Error.
+
+At the CMTS, if timer T1, T2 (only when in the Reserved state), or T4 expires, the Gate MUST be deleted. When a CMTS deletes a Gate without being solicited by the Policy Server, the CMTS MUST send a Gate-Report-State message (with the Solicited bit set to 0) to the Policy Server indicating that the Gate was deleted. If the T2 timer expires while in the Reserved state, the CMTS MUST delete the DOCSIS flow through DOCSIS mechanisms (i.e., a DSD message), and issue a Gate-Report-State message (with the Solicited bit set to 0) to the PS informing it of this state transition. Note, if the T2 timer expires while in the Committed or Committed-Recovery state then the CMTS must send a DSC as defined in DOCSIS to free the reserved resources that are in excess of the active resources, issue a Gate-Report-State message to the PS informing it of the reduction in reservation resources, and remain in the same state. Upon receipt of a Gate-Report-State message, the Policy Server MUST forward it to the Application Manager.
+
+### **6.5.9 Procedure for committing a gate**
+
+In Scenario 1, the Policy Server is responsible for committing a Gate through a Traffic Profile containing a Committed Envelope. The CMTS commits the Gate and activates the DOCSIS Service Flow using the parameters passed down to it by the Policy Server.
+
+### **6.5.10 Termination sequence**
+
+When the PEP is shutting down its TCP connection to the PDP, it MAY first send a Delete-Request-State (DRQ) message (including the Handle object used in the initial Request message). If
+
+the PEP chooses to send the DRQ message, the PEP MUST use COPS reason code 4 (Tear). The PEP MAY follow that with a Client-Close message. The PDP in response MUST automatically delete any state associated with the PEP when the TCP connection is terminated. When the PDP is going to shutdown, it SHOULD send a COPS Client-Close message to the PEP. In the COPS Client-Close message, the PDP SHOULD NOT send the PDP redirect address object PDPRedirAddr. If the PEP receives a COPS Client-Close message from the PDP with a PDPRedirAddr object, the PEP MUST ignore the PDPRedirAddr while processing the COPS Client-Close message.
+
+The PS and CMTS MUST NOT remove gates as a result of a failed COPS connection.
+
+### 6.5.11 Procedures for state synchronization
+
+When a Policy Server wants to synchronize its state with that of a CMTS, it MAY send a State-Synchronization-Request (SSQ) message. This SSQ MAY contain the Client-Handle of the Policy Server. If the optional Client-Handle is present, only state associated with this handle is synchronized. If the CMTS does not recognize the requested handle, it MUST immediately send a DRQ message to the Policy Server for the handle that was specified in the SSQ message. If no Client-Handle is specified in the SSQ message, all active states for clients with the IPCablecom Multimedia Client-Type MUST be synchronized with the PDP.
+
+The CMTS performs state synchronization by issuing Request messages for Gates associated with the Client-Handle (if included in the SSQ) or for all known Gates (if no Client-Handle is provided). When synchronization is complete, the CMTS MUST issue a Synchronize-State-Complete (SSC) message to the PDP. If the initiating SSQ contained a Client-Handle, then the corresponding SSC MUST also contain the Client-Handle.
+
+# 7 Event messaging interface description
+
+## 7.1 Introduction
+
+As in the IPCablecom-T architecture, event messages within IPCablecom Multimedia provide detailed information regarding QoS resource utilization, such as reservation, activation, and release. New for the IPCablecom Multimedia framework is the need to track status of policy decisions (requests, updates, deletions). Also, since use of network resources falls outside the profiles within IPCablecom-T (constant usage over time), there is the need to report volume-based and time-based usage information.
+
+Event messages, as defined in this framework, are generated by network elements and stored on the Record Keeping Server (RKS). These EMs are then correlated by the RKS or other back-office system to record a single instance of a service. These records may be used to derive service billing information, network resource usage patterns, capacity planning, etc. EMs are not, however, intended for fault monitoring.
+
+Currently, only the CMTS and Policy Server, which are part of the cable operator's network and considered trusted entities, generate EMs within the Multimedia framework. Other elements of the network, such as the various client types, are considered untrusted. In the case of the Application Manager, this element may or may not be part of the cable operator's network, and hence does not directly provide EMs to the RKS. The AM may, however, provide supplementary information as part of opaque data fields to the PS which would then be included in EMs generated by the PS.
+
+IPCablecom event messages for Multimedia represent a simplification and modification of IPCablecom-T event messages. Telephony-specific events such as Call\_Answer and Call\_Disconnect are considered optional, as are telephony service-specific event messages (e.g., Service Instance y). The intent is to leverage existing EM implementations as much as possible while providing sufficient abstraction mechanisms to support general Multimedia services.
+
+Specifically, of the fourteen EM message types defined in support of IPCablecom-T voice services, four will be required in IPCablecom Multimedia, including QoS\_Reserve, QoS\_Commit, QoS\_Release, and Time\_Change. Three new EM message types relating to policy decisions are defined: Policy\_Request, Policy\_Delete, and Policy\_Update. Table 5 provides a summary overview of the IPCablecom Multimedia EM message types.
+
+**Table 5/J.179 – IPCablecom multimedia EM message types**
+
+| Event message ID | Event message  | Originating element | Description                                                                                                                                                                                                           |
+|------------------|----------------|---------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 7                | QoS_Reserve    | CMTS                | Indicates the time at which the CMTS reserves bandwidth on the IPCablecom access network. The CMTS must also generate this event if the reserved bandwidth changes.                                                   |
+| 8                | QoS_Release    | CMTS                | Indicates the time at which the CMTS released its bandwidth commitment on the IPCablecom access network.                                                                                                              |
+| 17               | Time_Change    | PS, CMTS            | Captures an instance of a time change. Whenever the (IPCablecom) clock on a trusted network element (PS, and CMTS) is changed by more than 200 milliseconds, the network element MUST generate a Time_Change message. |
+| 19               | QoS_Commit     | CMTS                | Indicates the time at which the CMTS commits bandwidth on the IPCablecom access network. The CMTS must also generate this event if the committed bandwidth changes.                                                   |
+| 31               | Policy_Request | PS                  | Indicates the time at which the Policy Server receives a new policy request from the AM.                                                                                                                              |
+| 32               | Policy_Delete  | PS                  | Indicates the time at which the Policy Server deletes a policy.                                                                                                                                                       |
+| 33               | Policy_Update  | PS                  | Indicates the time at which the Policy Server receives a request to update a policy.                                                                                                                                  |
+
+Although IPCablecom Multimedia event messages are based upon IPCablecom-T, telephony-specific events are optional for IPCablecom Multimedia and are listed below. For further details on these events and associated attributes see ITU-T Rec. J.164 [10].
+
+**Table 6/J.179 – IPCablecom-T telephony EM message types**
+
+| Event message ID | Event message      | Description                                                                                                                                                              |
+|------------------|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 1                | Signaling_Start    | Indicates the time at which signalling starts.                                                                                                                           |
+| 2                | Signaling_Stop     | Indicates the time at which signalling terminates.                                                                                                                       |
+| 3                | Database_Query     | Indicates the time at which a one-time request/response transaction or database dip is completed by an intelligent peripheral (e.g., 800 number database, LNP database). |
+| 6                | Service_Instance   | Indicates the time at which the CMS provides an instance of a call control/feature service (e.g., call hold, call waiting).                                              |
+| 9                | Service_Activation | Indicates the time at which the CMS records an attempt to activate a service (e.g., call forwarding, call waiting).                                                      |
+
+**Table 6/J.179 – IPCablecom-T telephony EM message types**
+
+| <b>Event message ID</b> | <b>Event message</b> | <b>Description</b>                                                                                                                                                                                                                        |
+|-------------------------|----------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 10                      | Service_Deactivation | Indicates the time at which the CMS records an attempt to deactivate a service (e.g., call forwarding, call waiting).                                                                                                                     |
+| 13                      | Interconnect_Start   | Indicates the time at which the start of network interconnect signalling occurs.                                                                                                                                                          |
+| 14                      | Interconnect_Stop    | Indicates the termination of bandwidth between the IPCablecom network and the PSTN.                                                                                                                                                       |
+| 15                      | Call_Answer          | Indicates that the media connection is open because an answer event has occurred.                                                                                                                                                         |
+| 16                      | Call_Disconnect      | Indicates the time at which the media connection is closed because the calling party has terminated the call by going on-hook, or that the destination party has gone on-hook and the called-party's call-continuation timer has expired. |
+| 20                      | Media_Alive          | Indicates that service is active due to the continued existence of a bearer connection. This message may be generated by any trusted IPCablecom network element (CMS, MGC, and CMTS) as the vendor sees fit.                              |
+
+## 7.2 Record keeping server requirements
+
+The Record Keeping Server (RKS) is a trusted network element function. The RKS is generally depicted in this Recommendation as a distinct standalone element, but this Recommendation does not preclude some other application from performing the functions of an RKS, providing that the application conforms to the requirements herein.
+
+The RKS is the mediation layer between the IPCablecom Multimedia network and the back-office applications. The RKS is expected to process the data received from the IPCablecom Multimedia network and to present it to the back-office applications in the format and within the time constraints deemed necessary by the cable operator. The RKS, therefore, acts as a demarcation point between the IPCablecom network and the back-office applications.
+
+The RKS **MUST** be capable of receiving and processing Event Messages formatted in accordance with this Recommendation.
+
+The RADIUS messages, inside which Event Messages are encapsulated, are transported over UDP which does not guarantee reliable delivery of messages; hence the request/response nature of the protocol defined herein. When an RKS receives and successfully records all the IPCablecom Event Messages contained in a RADIUS Accounting-Request message, it **MUST** transmit an Accounting-Response message to the client. The RKS **MUST NOT** transmit an Accounting-Response reply if it fails to record successfully all the Event Messages in a RADIUS Accounting-Request message.
+
+The RKS **SHOULD** ignore Event Messages where the IPCablecom "Event Message type" is unrecognizable. The RKS **SHOULD** also ignore IPCablecom event attributes where the Event Attribute ID is unrecognizable.
+
+## 7.3 General IPCablecom multimedia network element requirements
+
+This clause lists requirements placed on the IPCablecom Multimedia network elements.
+
+### 7.3.1 Element ID
+
+Each IPCablecom network element that generates an Event Message MUST identify itself with a static, unique element ID. The Element ID is a statically configured element number, unique within an IPCablecom domain, which MUST be in the range 0 to 99 999.
+
+### 7.3.2 Timing
+
+It is important for elements that generate Event Messages to remain closely synchronized with one another and with a standard clock. The requirements in this clause ensure that such elements maintain this synchronization and report events with timestamps that are both accurate and precise.
+
+Elements that generate Event Messages MUST use the Network Time Protocol as defined in [2]. Elements MUST operate in mode 3 (Client mode). The value of NTP.MAXPOLL MUST NOT exceed eleven, which corresponds to 2048 seconds.
+
+Event Messages MUST include timestamps with a precision of one millisecond.
+
+### 7.3.3 Primary and secondary RKS considerations
+
+IPCablecom Multimedia supports an architecture that consists of a primary and secondary RKS. The secondary RKS is used as a fallback RKS when a network element (PS, CMTS) is unable to successfully send a message to the primary RKS. IPCablecom Multimedia network elements MUST support event message transport to a primary RKS and failover to a secondary RKS when communication with the primary RKS fails. Once a network element fails over to the secondary RKS, the secondary becomes the primary for the duration of that session or gate. The Policy Server is provisioned with primary and secondary RKSs as required for the applications it supports. The PS MUST provide the IP address and port of the primary RKS and optionally the secondary RKS to the CMTS in policy decision messages (Gate-Set). The PS MUST support multiple sets of primary and secondary RKSs.
+
+In order to guarantee the reliable transfer of the data the network elements should implement a user configurable retry time interval and the number of times the client needs to retransmit the event. The time interval should be configurable (suggested: 10 ms to 10 s), the number of retries should be configurable (suggested: 0 to 9). The number of retries should be attempted on both the primary RKS and secondary RKS. After exhausting the number of retries the event message should be written to an error file, and the event message can then be deleted from the network element.
+
+If the IPCablecom network element does not receive an Accounting-Response within the configured retry interval, it MUST continue resending the Accounting-Request until it receives an Accounting-Response from an RKS or the maximum number of retries is reached. The IPCablecom network element MUST re-send the same Accounting Request to the primary RKS and if the retry limit is reached, re-send the same Accounting Request to the secondary RKS.
+
+All Network Elements MUST store Event Messages until they have received an Acknowledgement (Accounting Response) from an RKS that the data was correctly received and stored, or until the maximum number of retries has been reached. Only when an Ack is received or the maximum retries reached are the network elements allowed to delete these Event Messages.
+
+Once a Network Element succeeds in sending event messages to the secondary RKS, a failover to the secondary RKS occurs. This is a non-revertive failover, meaning that the secondary RKS becomes active, and is the new primary RKS. All subsequent event messages for the session MUST be sent to the now active secondary RKS. For all new sessions, the PDP MUST instruct the PEP to use the new active RKS as the primary (i.e., the previous secondary RKS becomes the new primary for subsequent session). Note that it is possible under certain circumstances that one element, PS or CMTS, may be able to communicate with the primary RKS, while the other element may not, for the same session. In such cases, it is expected that the RKS be able to reconcile event messages between the primary and secondary RKS.
+
+### 7.3.4 Interaction with PacketCable RKS
+
+An Application Manager MAY provide an optional Event Generation Info object in a Gate-Set message. If present, this object MUST contain a valid BCID which can be used by the AM, PS, and CMTS to correlate billing information for the flow. If an Application Manager provides a BCID to the PS and the AM is trusted by the PS, the PS MAY use the BCID provided by the Application Manager.
+
+If an Application Manager provides an optional Event Generation Info object which specifies primary and secondary RKS IP Addresses that the Policy Server does not have knowledge of, the Policy Server MUST send the Event Messages for that transaction to the default primary RKS IP Address except in failover circumstances, in which case, the Event Messages MUST be sent to the default secondary RKS IP Address.
+
+The Application Manager MAY specify a primary RKS IP address in the optional Event Generation Info object or the Application Manager MAY allow the Policy Server to use its default primary and secondary RKS IP Addresses. If the AM specifies a primary RKS IP Address, it MAY also specify a secondary RKS IP Address. The Application Manager indicates that an RKS is not specified by setting the primary and secondary RKS IP address and port to zero.
+
+Regardless of what the Policy Server may receive from the Application Manager, the PS MUST direct the CMTS to use the same BCID and Primary/Secondary RKS IP Addresses and Ports which the Policy Server chooses to use. The PS should decide which RKS pair to send, based on AMID.
+
+## 7.4 Event messages for IPCablecom multimedia
+
+This clause provides a detailed description and definition of each of the Event Messages defined for IPCablecom Multimedia.
+
+### 7.4.1 Policy events
+
+The Policy Event Messages are new for IPCablecom Multimedia. They indicate the time at which the Policy Server receives a request for a policy action and serve to bracket the ensuing set of Event Messages for any resource usage associated with the various instances of a service. Policy event messages are used to indicate the initial policy request, an update to the policy, and the deletion of a policy.
+
+The PS MUST timestamp the Policy Event Messages upon receiving a policy request message from the AM. Immediately upon receiving an initial policy request, the PS MUST create a Billing Correlation ID (BCID). Each generated BCID MUST conform to the Billing Correlation ID (BCID) Attribute Structure format requirements in Table 17.
+
+The PS MUST include the BCID in the EM header for all subsequently generated Policy Event Messages associated with this request. Also, the PS MUST include the BCID in the Gate-Set message sent to the CMTS.
+
+The PS MUST generate policy event messages immediately after determining the result of a policy request. The result may be based upon PS internal authorization and admission control mechanisms or, upon receiving a response to its Gate-Set and Gate-Delete messages from the CMTS. The PS creates a timestamp for an event message when it receives a request from the AM but does not generate the event until it knows the outcome of the request.
+
+#### 7.4.1.1 Policy\_Request
+
+The Policy Server MUST send a Policy\_Request event message to the RKS if a request to create a new policy is received. The PS MUST set the Policy\_Decision\_Status to either Approved (1) or Declined (2), based upon the outcome of authorization and admission control.
+
+NOTE – Because the PS does not send the Policy\_Request event message until after the CMTS responds to the Gate-Set message, it is possible that QoS event messages from the CMTS may arrive at the RKS prior to a Policy-Request event message.
+
+**Table 7/J.179 – Policy\_Request event message**
+
+| Attribute name         | Required or optional | Comment                                                                                                                                                                                              |
+|------------------------|----------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Event_Message_Header   | R                    | See Table 16                                                                                                                                                                                         |
+| Application_Manager_ID | R                    | Contains the network wide unique identifier of the AM                                                                                                                                                |
+| Subscriber_ID          | R                    | Subscriber IPv4 address                                                                                                                                                                              |
+| Policy_Decision_Status | R                    | 1 – Policy Approved<br>2 – Policy Denied                                                                                                                                                             |
+| Policy_Denied_Reason   | O                    | Required when Policy_Decision_Status = 2 (Policy Denied)<br>1 – Policy Server admission control failure<br>2 – Insufficient resources<br>3 – Unknown subscriber<br>127 – Other                       |
+| FEID                   | R                    | Financial Entity ID. Identifies the paying entity. Supplied by the PS.                                                                                                                               |
+| AM_Opaque_Data         | O                    | If the Application Manager includes this object (ClientSI: Opaque-Data) in the "Policy Request" (COPS DEC), then the Policy Server MUST include this in the Policy-Event Event Message.              |
+| Volume_Usage_Limit     | O                    | If the Application manager includes this object (ClientSI: Volume-Based-Usage-Limit) in the "Policy Request" (COPS DEC), then the Policy Server MUST include this in the Policy-Event Event Message. |
+| Time_Usage_Limit       | O                    | If the Application manager includes this object (ClientSI: Time-Based-Usage-Limit) in the "Policy Request" (COPS DEC), then the Policy Server MUST include this in the Policy-Event Event Message.   |
+
+#### 7.4.1.2 Policy\_Delete
+
+The Policy Server MUST send a Policy\_Delete Event Message to the RKS when it receives a Gate-Delete from the AM indicating that the resources are no longer needed for a session, a Gate-Delete-Ack from the CMTS in response to a PS initiated Gate-Delete, or a Gate-Report-State from the CMTS indicating that the resources are no longer available for a session. The PS MUST always generate a Policy\_Delete Event Message to close a session if it has previously generated a Policy-Request Event Message to open the session.
+
+**Table 8/J.179 – Policy\_Delete event message**
+
+| Attribute name         | Required or optional | Comment                                               |
+|------------------------|----------------------|-------------------------------------------------------|
+| Event_Message_Header   | R                    | See Table 16                                          |
+| Application_Manager_ID | R                    | Contains the network wide unique identifier of the AM |
+| Subscriber_ID          | R                    | Subscriber IPv4 address                               |
+
+**Table 8/J.179 – Policy\_Delete event message**
+
+| Attribute name        | Required or optional | Comment                                                                                                                                                                                 |
+|-----------------------|----------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Policy_Deleted_Reason | R                    | 1 – Application Manager request<br>2 – CMTS decision<br>127 – Other                                                                                                                     |
+| FEID                  | R                    | Financial Entity ID. Identifies the paying entity. Supplied by the PS.                                                                                                                  |
+| AM_Opaque_Data        | O                    | If the Application Manager includes this object (ClientSI: Opaque-Data) in the "Policy Request" (COPS DEC), then the Policy Server MUST include this in the Policy-Event Event Message. |
+
+#### 7.4.1.3 Policy\_Update
+
+The Policy Server MUST send a Policy\_Update Event Message to the RKS if a request to change the traffic profile, classifier, volume limit, time limit, or opaque data of a gate is received from the AM.
+
+**Table 9/J.179 – Policy\_Update event message**
+
+| Attribute name         | Required or optional | Comment                                                                                                                                                                                                                                                                  |
+|------------------------|----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Event Message Header   | R                    | See Table 16                                                                                                                                                                                                                                                             |
+| Application_Manager_ID | R                    | Contains the network wide unique identifier of the AM                                                                                                                                                                                                                    |
+| SubscriberID           | R                    | SubscriberID                                                                                                                                                                                                                                                             |
+| Policy_Decision_Status | R                    | 1 – Policy Approved<br>2 – Policy Denied                                                                                                                                                                                                                                 |
+| Policy_Denied_Reason   | O                    | Required when Policy_Decision_Status = 2 (Policy Denied)<br>1 – Policy Server admission control failure<br>2 – Insufficient resources<br>3 – Unknown subscriber<br>4 – Unauthorized AMID<br>5 – Undefined Service Class Name<br>6 – Incompatible Envelope<br>127 – Other |
+| Policy_Update_Reason   | R                    | 1 – Traffic Profile<br>2 – Classifier<br>3 – Volume Limit<br>4 – Time Limit<br>5 – Opaque data<br>6 – Multiple Updates (combination of 1-5)<br>127 – Other                                                                                                               |
+
+**Table 9/J.179 – Policy\_Update event message**
+
+| Attribute name     | Required or optional | Comment                                                                                                                                                                                              |
+|--------------------|----------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| FEID               | R                    | Financial Entity ID. Identifies the paying entity. Supplied by the PS.                                                                                                                               |
+| AM_Opaque_Data     | O                    | If the Application Manager includes this object (ClientSI: Opaque-Data) in the "Policy Request" (COPS DEC), then the Policy Server MUST include this in the Policy-Event Event Message.              |
+| Volume_Usage_Limit | O                    | If the Application Manager includes this object (ClientSI: Volume-Based-Usage-Limit) in the "Policy Request" (COPS DEC), then the Policy Server MUST include this in the Policy-Event Event Message. |
+| Time_Usage_Limit   | O                    | If the Application Manager includes this object (ClientSI: Time-Based-Usage-Limit) in the "Policy Request" (COPS DEC), then the Policy Server MUST include this in the Policy-Event Event Message.   |
+
+### 7.4.2 QoS\_Reserve
+
+This Event Message indicates the time at which the CMTS reserves bandwidth on the IPCablecom access Network. The CMTS MUST also generate this event if the Reserved bandwidth changes.
+
+The CMTS MUST timestamp this message immediately upon transmission of a DSA-ACK or DSC-ACK acknowledging a successful DSA-RSP or DSC-RSP to the CM which completes a transaction reserving resources.
+
+If the DSA-RSP or DSC-RSP confirmation code from the CM is not successful, the CMTS MUST NOT generate this message.
+
+**Table 10/J.179 – QoS\_Reserve event message**
+
+| Attribute name         | Required or optional | Comment                                                |
+|------------------------|----------------------|--------------------------------------------------------|
+| Event Message Header   | R                    | See Table 16                                           |
+| QoS_Descriptor         | R                    | None                                                   |
+| SF_ID                  | R                    | None                                                   |
+| Flow_Direction         | R                    | None                                                   |
+| Element_Requesting_QoS | R                    | 0 = Client<br>1 = Policy Server<br>2 = Embedded Client |
+
+### 7.4.3 QoS\_Commit
+
+The QoS\_Commit Event Message indicates the time at which the CMTS commits bandwidth on the IPCablecom access Network. The CMTS MUST also generate this event if the Committed bandwidth changes.
+
+The CMTS MUST timestamp this message immediately upon transmission of a DSA-ACK or DSC-ACK acknowledging a successful DSA-RSP or DSC-RSP to the CM which completes a transaction committing resources.
+
+If the DSA-RSP or DSC-RSP confirmation code from the CM is not successful, the CMTS MUST NOT generate this message.
+
+**Table 11/J.179 – QoS\_Commit event message**
+
+| Attribute name       | Required or optional | Comment      |
+|----------------------|----------------------|--------------|
+| Event Message Header | R                    | See Table 16 |
+| QoS_Descriptor       | R                    | None         |
+| SF ID                | R                    | None         |
+| Flow_Direction       | R                    | None         |
+
+### 7.4.4 QoS\_Release
+
+The QoS\_Release Event Message indicates the time at which the CMTS releases its reservation and/or bandwidth commitment on the IPCablecom access network.
+
+The CMTS MUST timestamp this message immediately upon Transmission of a DSD-REQ that indicates the request to delete bandwidth.
+
+**Table 12/J.179 – QoS\_Release event message**
+
+| Attribute name       | Required or optional | Comment                                                                                                                                                                                                                 |
+|----------------------|----------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Event Message Header | R                    | See Table 16                                                                                                                                                                                                            |
+| SF ID                | R                    | None                                                                                                                                                                                                                    |
+| Flow_Direction       | R                    | None                                                                                                                                                                                                                    |
+| QoS_Release_Reason   | R                    | 1 – Gate Closed by PS<br>2 – Inactivity resource recovery (T4) timer expiration<br>3 – CM Failure<br>4 – Pre-Empted<br>5 – RSVP PathTear request<br>6 – CM request<br>7 – Admitted (T2) timer expiration<br>127 – Other |
+| Gate_Usage_Info      | R                    | None                                                                                                                                                                                                                    |
+| Gate_Time_Info       | R                    | None                                                                                                                                                                                                                    |
+
+### 7.4.5 Time\_Change
+
+This event captures an instance of a time change. Whenever the (IPCablecom) clock on the network element (PS or CMTS) is changed by more than 200 milliseconds, the network element MUST generate a Time Change message. This includes time shift events (Daylight savings time), step adjustments to synchronize with the NTP reference clock and manual time setting changes. The Event\_Time attribute in the Event Message header MUST reflect the new (adjusted) notion of time. Note that Time\_Change message is not required for slew adjustments performed by NTP.
+
+The network element (PS and CMTS) MUST send the Time\_Change event message to the active (current primary) RKS. The Time\_Change event message MUST be generated when a gate(s) is currently present in the CMTS. The Time\_Change event message need not be generated when there
+
+are no gates in the CMTS. Only one Time\_Change event message is sent to each primary RKS regardless of how many gates may exist on the CMTS. In other words, if the CMTS has several gates, all of which point to the same RKS, then only one Time\_Change event message should be sent to that RKS.
+
+The BCID in the Event Message Header of the Time\_Change event message MUST be generated locally by the network element at the time of the event. The BCID is not associated with any session related BCID, it is a unique BCID for this event.
+
+**Table 13/J.179 – Time\_Change event message**
+
+| Attribute name       | Required or optional | Comment      |
+|----------------------|----------------------|--------------|
+| Event Message Header | R                    | See Table 16 |
+| Time_Adjustment      | R                    | None         |
+
+## 7.5 Event messaging attributes for IPCablecom multimedia
+
+This clause describes and defines the IPCablecom attributes included in the IPCablecom Event Messages.
+
+Table 14 provides a mapping between each of the IPCablecom Event Messages and their associated attributes. Table 15 offers a detailed description of each of these attributes.
+
+**Table 14/J.179 – IPCablecom attributes mapped to IPCablecom MM event messages**
+
+| EM attribute ID | EM attribute name      | 7 – QoS_Reserve | 8 – QoS_Release | 17 – Time_Change | 19 – QoS_Commit | 31 – Policy_Request | 32 – Policy_Delete | 33 – Policy_Update |
+|-----------------|------------------------|-----------------|-----------------|------------------|-----------------|---------------------|--------------------|--------------------|
+| 1               | Event_Message_Header   | X               | X               | X                | X               | X                   | X                  | X                  |
+| 30              | SF_ID                  | X               | X               |                  | X               |                     |                    |                    |
+| 32              | QoS_Descriptor         | X               |                 |                  | X               |                     |                    |                    |
+| 38              | Time_Adjustment        |                 |                 | X                |                 |                     |                    |                    |
+| 49              | FEID                   |                 |                 |                  |                 | X                   | X                  | X                  |
+| 50              | Flow_Direction         | X               | X               |                  | X               |                     |                    |                    |
+| 61              | AM_Opaque_Data         |                 |                 |                  |                 | X                   | X                  | X                  |
+| 62              | Subscriber_ID          |                 |                 |                  |                 | X                   | X                  | X                  |
+| 63              | Volume_Usage_Limit     |                 |                 |                  |                 | X                   |                    | X                  |
+| 64              | Gate_Usage_Info        |                 | X               |                  |                 |                     |                    |                    |
+| 65              | Element_Requesting_Qos | X               |                 |                  |                 |                     |                    |                    |
+| 66              | QoS_Release_Reason     |                 | X               |                  |                 |                     |                    |                    |
+| 67              | Policy_Denied_Reason   |                 |                 |                  |                 | X                   |                    | X                  |
+| 68              | Policy_Deleted_Reason  |                 |                 |                  |                 |                     | X                  |                    |
+| 69              | Policy_Update_Reason   |                 |                 |                  |                 |                     |                    | X                  |
+
+**Table 14/J.179 – IPCablecom attributes mapped to IPCablecom MM event messages**
+
+| EM attribute ID | EM attribute name      | 7 – QoS_Reserve | 8 – QoS_Release | 17 – Time_Change | 19 – QoS_Commit | 31 – Policy_Request | 32 – Policy_Delete | 33 – Policy_Update |
+|-----------------|------------------------|-----------------|-----------------|------------------|-----------------|---------------------|--------------------|--------------------|
+| 70              | Policy_Decision_Status |                 |                 |                  |                 | X                   |                    | X                  |
+| 71              | Application_Manager_ID |                 |                 |                  |                 | X                   | X                  | X                  |
+| 72              | Time_Usage_Limit       |                 |                 |                  |                 | X                   |                    | X                  |
+| 73              | Gate_Time_Info         |                 | X               |                  |                 |                     |                    |                    |
+
+Table 15 provides a detailed definition of each of the IPCablecom Event Message attributes. A data value of an attribute may either be represented by a simple data format (one data field) or by a more complex data structure.
+
+**Table 15/J.179 – IPCablecom MM event message attributes**
+
+| EM attribute ID | EM attribute length   | EM attribute name | EM attribute value type        | Attribute data description                                                                                                                                                                                                                                                                      |
+|-----------------|-----------------------|-------------------|--------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 1               | 76 bytes              | EM_Header         | Data structure<br>See Table 16 | Common data required on every IPCablecom Event Message                                                                                                                                                                                                                                          |
+| 30              | 4 bytes               | SF_ID             | Unsigned integer               | Service Flow ID, a 32-bit integer assigned by the CMTS to each DOCSIS Service Flow defined within a DOCSIS RF MAC domain. SFIDs are considered to be in either the upstream direction (USFID) or downstream direction (DSFID). USFIDs and DSFIDs are allocated from the same SFID number space. |
+| 32              | Variable; Min 8 bytes | QoS_Desccriptor   | Data structure<br>See Table 19 | QoS parameters data                                                                                                                                                                                                                                                                             |
+| 38              | 8 bytes               | Time_Adjustment   | Signed integer                 | Time adjustment of an element's (PS, CMTS) clock.<br><br>This time is in milliseconds, detailing the amount of the time change.                                                                                                                                                                 |
+
+**Table 15/J.179 – IPCablecom MM event message attributes**
+
+| <b>EM attribute ID</b> | <b>EM attribute length</b>            | <b>EM attribute name</b> | <b>EM attribute value type</b> | <b>Attribute data description</b>                                                                                                                                                                                                                                                                                                                  |
+|------------------------|---------------------------------------|--------------------------|--------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 49                     | Variable length, maximum of 247 bytes | FEID                     | ASCII character string.        | Financial Entity ID. The first 8 bytes constitute cable operator defined data. By default, the first 8 bytes are zero filled. From the 9th byte on the field contains the cable operator's domain name which uniquely identifies the cable operator for billing and settlement purposes. The cable operator's domain name is limited to 239 bytes. |
+| 50                     | 2 bytes                               | Flow Direction           | Unsigned integer               | Flow direction:<br>0 = Reserved<br>1 = Upstream<br>2 = Downstream                                                                                                                                                                                                                                                                                  |
+| 61                     | 8 bytes                               | AM_Opaque_Data           | Unsigned integer               | Opaque data passed from Application Manager.                                                                                                                                                                                                                                                                                                       |
+| 62                     | 4 bytes                               | Subscriber_ID            | Unsigned integer               | 4 concatenated byte values representing an IPv4 address                                                                                                                                                                                                                                                                                            |
+| 63                     | 8 bytes                               | Volume_Usage_Limit       | Unsigned integer               | Volume limit in octets set by the AM                                                                                                                                                                                                                                                                                                               |
+| 64                     | 8 bytes                               | Gate_Usage_Info          | Unsigned integer               | The number of octets transmitted on the DOCSIS RF network from the byte after the MAC header HCS to the end of the CRC                                                                                                                                                                                                                             |
+| 65                     | 2 bytes                               | Element_Requesting_QoS   | Unsigned integer               | 0 = Client<br>1 = Policy Server<br>2 = Embedded Client                                                                                                                                                                                                                                                                                             |
+| 66                     | 2 bytes                               | QoS_Release_Reason       | Unsigned integer               | 1 – Gate Closed by PS<br>2 – Inactivity resource recovery (T4) timer expiration<br>3 – CM Failure<br>4 – Pre-Empted<br>5 – RSVP PathTear request<br>6 – CM request<br>7 – Admitted (T2) timer expiration<br>127 – Other                                                                                                                            |
+
+**Table 15/J.179 – IPCablecom MM event message attributes**
+
+| <b>EM attribute ID</b> | <b>EM attribute length</b> | <b>EM attribute name</b> | <b>EM attribute value type</b> | <b>Attribute data description</b>                                                                                                                                                                            |
+|------------------------|----------------------------|--------------------------|--------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 67                     | 2 bytes                    | Policy_Denied_Reason     | Unsigned integer               | 1 – Policy Server admission control failure<br>2 – Insufficient resources<br>3 – Unknown subscriber<br>4 – Unauthorized AMID<br>5 – Undefined Service Class Name<br>6 – Incompatible Envelope<br>127 – Other |
+| 68                     | 2 bytes                    | Policy_Deleted_Reason    | Unsigned integer               | 1 – Application Manager request<br>2 – CMTS decision<br>127 – Other                                                                                                                                          |
+| 69                     | 2 bytes                    | Policy_Update_Reason     | Unsigned integer               | 1 – Traffic Profile<br>2 – Classifier<br>3 – Volume Limit<br>4 – Time Limit<br>5 – Opaque data<br>6 – Multiple Updates (combination of 1-5)<br>127 – Other                                                   |
+| 70                     | 2 bytes                    | Policy_Decision_Status   | Unsigned integer               | 1 – Policy Approved<br>2 – Policy Denied                                                                                                                                                                     |
+| 71                     | 4 bytes                    | Application_Manager_ID   | Unsigned integer               | Network-wide unique identifier assigned to the Application Manager.                                                                                                                                          |
+| 72                     | 4 bytes                    | Time_Usage_Limit         | Unsigned integer               | Time limit in seconds set by the AM                                                                                                                                                                          |
+| 73                     | 4 bytes                    | Gate_Time_Info           | Unsigned integer               | The number of seconds a gate has been in either the Committed or Committed Recovery state                                                                                                                    |
+
+### 7.5.1 EM\_Header attribute structure
+
+Table 16 contains a detailed description of the fields in the EM\_Header attribute structure. This Event Message Header attribute MUST be the first attribute in every IPCablecom Event Message.
+
+**Table 16/J.179 – EM\_Header attribute structure**
+
+| Field name         | Semantics                                                                                                                                                                                                                                                                                                                                      | Value type                                           | Length            |
+|--------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------|-------------------|
+| Version ID         | Identifies version of this EM Header structure.<br>1 = IPCablecom 1.0<br>2 = IPCablecom 1.1<br>3 = IPCablecom Multimedia<br>NOTE – A value of 2 or 3 indicates the Event_Object field in this header is used.<br>The PS and CMTS network elements MUST set the value of the Version_ID to 3.                                                   | Unsigned integer                                     | 2 bytes           |
+| BCID               | Unique identifier for a transaction within a network.                                                                                                                                                                                                                                                                                          | Data Structure<br>See Table 17                       | 24 bytes          |
+| Event Message Type | Identifies the type of Event Message.                                                                                                                                                                                                                                                                                                          | Unsigned integer                                     | 2 bytes           |
+| Element Type       | Identifies Type of Originating Element:<br>0 = Reserved<br>1 = Reserved<br>2 = CMTS<br>3 = Reserved<br>4 = Policy Server                                                                                                                                                                                                                       | Unsigned integer                                     | 2 bytes           |
+| Element ID         | Network-wide unique identifier<br>5 digits (statically configured element number unique within an IPCablecom domain in the range of 0-99999)                                                                                                                                                                                                   | Right justified, space padded ASCII Character String | 8 bytes           |
+| Time Zone          | Identifies daylight savings time and offset from universal time (UTC).<br>Daylight Savings Time:<br>0 = Standard Time<br>1 = Daylight Savings<br>UTC offset + HHMMSS<br>The offset is reported from the network element (PS, CMTS) point of view; not based on the subscriber point of view.                                                   | ASCII character string                               | 1 byte<br>7 bytes |
+| Sequence Number    | Each network element MUST assign a unique and monotonically increasing unsigned integer for each Event Message sent to a given RKS. For the purpose of this Recommendation, monotonically increasing is to be interpreted as increasing by 1. This is used by the RKS to determine if Event Messages are missing from a given network element. | Unsigned integer                                     | 4 bytes           |
+
+**Table 16/J.179 – EM\_Header attribute structure**
+
+| Field name      | Semantics                                                                                                                                                                                                                                                                                                                                                       | Value type             | Length   |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------|----------|
+| Event_time      | Event generation time and date. Millisecond granularity.<br>Format: yyyymmddhhmmss.mmm                                                                                                                                                                                                                                                                          | ASCII character string | 18 bytes |
+| Status          | Status indicators                                                                                                                                                                                                                                                                                                                                               | See Table 18           | 4 bytes  |
+| Priority        | Indicates the importance to assign relative to other event messages.<br>255 = highest priority<br>0 = lowest priority<br>128 = default.                                                                                                                                                                                                                         | Unsigned integer       | 1 byte   |
+| Attribute Count | Indicates the number of attributes that follow (or are appended to) this header in the current Event Message                                                                                                                                                                                                                                                    | Unsigned integer       | 2 bytes  |
+| Event Object    | The Event_Object field allows for a grouping of services.<br>0 = Accounting Event Message<br>1 = Reserved<br>The PS and CMTS network elements MUST set the value of the Event_Object field to 0 if the EM_Header Version_ID is 3 (IPCablecom Multimedia Event Message to the RKS).<br>The RKS MUST discard EM messages when the Event_Object field is set to 1. | Unsigned integer       | 1 byte   |
+
+### 7.5.2 Billing correlation ID (BCID) field structure
+
+Table 17 describes the Billing Correlation ID field (BCID). The RKS, or some other back-office application, uses the BCID to correlate Event Messages that are generated for a single transaction. It is one of the fields in the Event Message Header Attribute. The BCID is unique for each transaction in the network. All Event Messages from the same network element with the same BCID MUST be sent to the same primary RKS except in failover circumstances in which case the Event Messages MUST be sent to secondary RKS.
+
+**Table 17/J.179 – BCID field description**
+
+| Field name    | Semantics                                                                                                                                                                                                                                                                                         | Value type                                           | Length            |
+|---------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------|-------------------|
+| Timestamp     | High-order 32 bits of NTP time reference                                                                                                                                                                                                                                                          | Unsigned integer                                     | 4 bytes           |
+| Element_ID    | Network-wide unique identifier<br>5 digits (statically configured element number unique within an IPCablecom domain in the range of 0-99999)                                                                                                                                                      | Right justified, space padded ASCII character string | 8 bytes           |
+| Time Zone     | Identifies daylight savings time and offset from universal time (UTC).<br>Daylight Savings Time:<br>0 = Standard Time<br>1 = Daylight Savings<br>UTC offset: $\pm$ HHMMSS<br>The offset is reported from the network element (PS, CMTS) point of view; not based on the subscriber point of view. | ASCII character string                               | 1 byte<br>7 bytes |
+| Event Counter | Monotonically increasing for each Transaction                                                                                                                                                                                                                                                     | Unsigned integer                                     | 4 bytes           |
+
+### **7.5.3 Status field structure**
+
+The Status field of the Event Message Header Attribute is a 32-bit mask. Bit 0 is the low-order bit; the field is treated as a 4-byte unsigned integer. Table 18 presents Status field description.
+
+**Table 18/J.179 – Status field description**
+
+| Start bit | Semantics                                                                                                                                                     | Bit count |
+|-----------|---------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------|
+| 0-1       | Error Indicator:<br>0 = No Error<br>1 = Possible Error<br>2 = Known Error<br>3 = Reserved                                                                     | 2         |
+| 2         | Event Origin:<br>0 = Trusted Element<br>1 = Untrusted Element                                                                                                 | 1         |
+| 3         | Event Message Proxied:<br>0 = Not proxied, all data known by sending element<br>1 = proxied, data sent by a trusted element on behalf of an untrusted element | 1         |
+| 4-31      | Reserved. The Status field bits 4 to 31 MUST be set to 0.                                                                                                     | 28        |
+
+### 7.5.4 QoS descriptor attribute structure
+
+Table 19 describes the QoS Descriptor Data Structure.
+
+**Table 19/J.179 – QoS descriptor data structure**
+
+| Field name          | Semantics                                              | Value type                                           | Length                                            |
+|---------------------|--------------------------------------------------------|------------------------------------------------------|---------------------------------------------------|
+| Status_Bitmask      | Bitmask describing structure contents. (See Table 20)  | Bit map                                              | 4 bytes                                           |
+| Service_Class_Name  | Service profile name                                   | Right justified, space padded ASCII character string | 16 bytes                                          |
+| QoS_Parameter_Array | QoS Parameters. Contents determined by Status Bitmask. | Unsigned integer array                               | Variable length array of 32-bit unsigned integers |
+
+Table 20 describes the QoS Status Bitmask field of the QoS Descriptor attribute. Bits 2-17 describe the contents of the QoS\_Parameter\_Array. Each of these bits indicates the presence (bit = 1) or absence (bit = 0) of the named QoS parameter in the array. The location of a particular QoS parameter in the array matches the order in which that parameter's bit is encountered in the bitmask, starting from the low-order bit.
+
+Each QoS parameter present in the QoS\_Parameter\_Array must occupy four bytes. The definition and encoding of the QoS parameters can be found in Annex C of the DOCSIS RFI Recommendation. QoS parameters whose definition specifies less than four bytes must be right-justified (where the 4 bytes are to be treated as an unsigned integer) in the four bytes allocated for the array element.
+
+**Table 20/J.179 – QoS status bitmask**
+
+| Start bit | Semantics                                                                                                                                   | Bit count |
+|-----------|---------------------------------------------------------------------------------------------------------------------------------------------|-----------|
+| 0         | State Indication:<br>0 = Illegal Value<br>1 = Resource Reserved but not Activated<br>2 = Illegal Value<br>3 = Resource Reserved & Activated | 2         |
+| 2         | Service Flow Scheduling Type                                                                                                                | 1         |
+| 3         | Nominal Grant Interval                                                                                                                      | 1         |
+| 4         | Tolerated Grant Jitter                                                                                                                      | 1         |
+| 5         | Grants Per Interval                                                                                                                         | 1         |
+| 6         | Unsolicited Grant Size                                                                                                                      | 1         |
+| 7         | Traffic Priority                                                                                                                            | 1         |
+| 8         | Maximum Sustained Rate                                                                                                                      | 1         |
+| 9         | Maximum Traffic Burst                                                                                                                       | 1         |
+| 10        | Minimum Reserved Traffic Rate                                                                                                               | 1         |
+| 11        | Minimum Packet Size                                                                                                                         | 1         |
+| 12        | Maximum Concatenated Burst                                                                                                                  | 1         |
+| 13        | Request/Transmission Policy                                                                                                                 | 1         |
+
+**Table 20/J.179 – QoS status bitmask**
+
+| Start bit | Semantics                   | Bit count |
+|-----------|-----------------------------|-----------|
+| 14        | Nominal Polling Interval    | 1         |
+| 15        | Tolerated Poll Jitter       | 1         |
+| 16        | IP Type of Service Override | 1         |
+| 17        | Maximum Downstream Latency  | 1         |
+
+## 7.6 RADIUS accounting protocol
+
+This clause specifies the protocol used between the IPCablecom network elements that generate Event Messages (PS, CMTS) and the Record Keeping Server (RKS). These network elements MUST support RADIUS Accounting (RFC 2866) [8] with IPCablecom extensions as defined in this Recommendation.
+
+The RADIUS Accounting protocol is a client/server protocol that consists of two message types: Accounting-Request and Accounting-Response. IPCablecom network elements that generate Event Messages are RADIUS clients that send Accounting-Request messages to the RKS. The RKS is a RADIUS server that sends Accounting-Response messages back to the IPCablecom network elements indicating that it has successfully received and stored the Event Message.
+
+The Event Messages are formatted as RADIUS Accounting-Request and Accounting-Response packets as specified in [8].
+
+### 7.6.1 Authentication and confidentiality
+
+Refer to clause 8 for details concerning the use of IPsec to provide both authentication and confidentiality of the RADIUS messages, and the details of the correct usage of the RADIUS shared secret.
+
+### 7.6.2 Standard RADIUS attributes
+
+Each RADIUS message starts with the standard RADIUS header shown in Table 21.
+
+**Table 21/J.179 – RADIUS message header**
+
+| Field name    | Semantics                                                            | Field length |
+|---------------|----------------------------------------------------------------------|--------------|
+| Code          | Accounting-Request = 4<br>Accounting-Response = 5                    | 1 byte       |
+| Identifier    | Used to match accounting-request and accounting-response messages.   | 1 byte       |
+| Length        | Total length of RADIUS message<br>min value = 20<br>max value = 4096 | 2 bytes      |
+| Authenticator | Computed as per RADIUS Specification                                 | 16 bytes     |
+
+Two standard RADIUS attributes MUST follow the RADIUS Message Header: NAS-IP-Address and Acct\_Status\_Type. These two fields are included to improve interoperability with existing RADIUS server implementations since they are mandatory attributes in a RADIUS Accounting-Request packet.
+
+The NAS-IP-Address indicates the originator of the Accounting-Request message and MUST contain the IP address of the originating IPCablecom network element.
+
+The Acct-Status-Type attribute typically indicates whether the Accounting-Request marks the beginning of the user service (Start) or the end (Stop). An IPCablecom Accounting-Request message may contain the beginning, end, or update of the user service. For this reason, an Acct-Status-Type value of Interim-Update is used to represent IPCablecom Event Messages.
+
+**Table 22/J.179 – Mandatory RADIUS attributes**
+
+| Name             | Type | Length | Value                                                |
+|------------------|------|--------|------------------------------------------------------|
+| NAS-IP-Address   | 4    | 6      | IP address of originating IPCablecom network element |
+| Acct-Status-Type | 40   | 6      | Interim-Update=3                                     |
+
+**Table 23/J.179 – RADIUS Acct\_Status\_Type**
+
+| Type | Length  | Value              |
+|------|---------|--------------------|
+| 40   | 6 bytes | Interim-Update = 3 |
+
+IPCablecom attributes are encoded in the RADIUS Vendor Specific Attributes (VSA) structure as described in this clause. Additional IPCablecom or vendor-specific attributes can be added to existing Event Messages by adding additional RADIUS VSAs to the message.
+
+The Vendor-Specific attribute includes a field to identify the vendor, and the Internet Assigned Numbers Authority (IANA) has assigned IPCablecom an SMI Network Management Private Enterprise Number of 4491 for the encoding of these attributes.
+
+**Table 24/J.179 – Radius VSA structure for IPCablecom attributes**
+
+| Field name              | Semantics                                                   | Field length                                              |
+|-------------------------|-------------------------------------------------------------|-----------------------------------------------------------|
+| Type                    | Vendor Specific = 26                                        | 1 byte                                                    |
+| Length                  | Total Attribute Length<br>NOTE – Value is Vendor Length + 8 | 1 byte                                                    |
+| Vendor ID               | CableLabs = 4491                                            | 4 bytes                                                   |
+| Vendor Attribute Type   | IPCablecom Attribute Type                                   | 1 byte (see Table 15)                                     |
+| Vendor Attribute Length | IPCablecom Attribute Length                                 | 1 byte (see Table 15)<br>NOTE – Value is Vendor Length +2 |
+| Vendor Attribute Value  | IPCablecom Attribute Value                                  | Vendor Length bytes                                       |
+
+### 7.6.3 IPCablecom RADIUS accounting-request packet syntax
+
+```
+<<RADIUS Accounting-Request> ::=
+  <RADIUS message Header>
+  <RADIUS NAS-IP-Address Attribute>
+  <RADIUS Acct-Status-Type Attribute>
+  <Packet Cable EM>
+<Packet Cable EM> ::=
+  <RADIUS VSA for IPCablecom EM Header Attribute>
+  <IPCablecom EM Attribute List>
+```
+
+```
+
+<IPCablecom EM Attribute List> ::=
+  <RADIUS VSA for IPCablecom EM Attribute> |
+  <IPCablecom EM Attribute List>
+  <RADIUS VSA for Packet Cable EM Attribute>>
+
+```
+
+The Event Message Header is the first attribute within a given Event Message. The order of the Event Message attributes which follow the Event Message Header is arbitrary.
+
+IPCablecom extends RADIUS Accounting, by introducing new attributes and new values for existing attributes. Since the RADIUS protocol is extendable in this manner, it is expected that existing RADIUS server implementations will require minimal modifications to support the batch collection of IPCablecom Event Messages.
+
+# 8 Security requirements
+
+Security for IPCablecom Multimedia interfaces utilizes security mechanisms defined in [11] as well as in [1]. Table 25 provides a summary of security mechanisms for each of the IPCablecom Multimedia interfaces.
+
+**Table 25/J.179 – Multimedia security interfaces**
+
+| Interface | Description                              | Security mechanisms                                   |
+|-----------|------------------------------------------|-------------------------------------------------------|
+| pkt-mm-1  | CMTS – CM                                | HMAC-based authentication defined by Annex B/J.112.   |
+| pkt-mm-2  | PS – CMTS                                | IPsec ESP using IKE or Kerberos-based key management. |
+| pkt-mm-3  | AM – PS                                  | IPsec ESP using IKE or Kerberos-based key management. |
+| pkt-mm-4  | PS – RKS                                 | IPsec ESP using IKE or Kerberos-based key management. |
+| pkt-mm-5  | CMTS – RKS                               | IPsec ESP using IKE or Kerberos-based key management. |
+| pkt-mm-6  | Client – CMTS                            | Out of scope for this version of this Recommendation. |
+| pkt-mm-7  | Client – AM                              | Out of scope for this version of this Recommendation. |
+| pkt-mm-8  | AM – Peer                                | Out of scope for this version of this Recommendation. |
+| pkt-mm-9  | CMTS – cable operator-Managed IP Network | Out of scope for this version of this Recommendation. |
+| pkt-mm-10 | Client – Peer                            | Out of scope for this version of this Recommendation. |
+
+The following clauses describe security that is applied to each IPCablecom Multimedia interface and specify additional requirements or extensions whenever necessary.
+
+## 8.1 CMTS – CM QoS interface (pkt-mm-1)
+
+Annex B/J.112 QoS messages are authenticated using an HMAC (Hash Message Authentication Code), which is a keyed cryptographic hash. Calculation of the HMAC attribute that must be included in Annex B/J.112 QoS messages is specified in B.C.1.4.1 of [1].
+
+## 8.2 Policy server – CMTS COPS interface (pkt-mm-2)
+
+The Policy Server – CMTS COPS interface MUST be secured using the IPsec ESP protocol, as specified in 7.2.1.3.2 of [11]. The key management requirements for this interface MUST comply with 7.2.1.4.1 of [11]. For this interface, Policy Server MUST comply with all the Gate Controller requirements listed in 7.2.1.3.2 and 7.2.1.4.1 of [11]. IKE with pre-shared keys is required to implement, while IKE with certificates and Kerberized IPsec are both optional to implement.
+
+In the case that Kerberized IPsec is utilized, clause 6.4.5 of [11] defines principal names of various Kerberized services. The first component of a principal name is unique for each type of a
+
+Kerberized service. Clause 6.4.5 of [11] already specifies the first component of the CMTS's principal name. The first component of Policy Server's principal name MUST be:
+
+policyserver:<ElementID>
+
+where <ElementID> is defined in 6.4.5 of [11].
+
+In the case that IKE with certificates is utilized, the subject name in a server certificate has the following attribute defined in 8.2.3.4.3 of [11]:
+
+OU=<Sub-System Name>
+
+The value of <Sub-System Name> identifies a server type. The value of <Sub-System Name> for a CMTS is already specified in 8.2.3.4.3 of [11]. The value of <Sub-System Name> for a Policy Server MUST be the following string: policyserver.
+
+## 8.3 Application manager – Policy server COPS interface (pkt-mm-3)
+
+The Application Manager – Policy Server COPS interface MUST be secured using the IPsec ESP protocol, as specified in 7.2.1.3.2 of [11]. The key management requirements for this interface MUST comply with 7.2.1.4.1 of [11]. For this interface, Application Manager MUST comply with all the Gate Controller requirements listed in 7.2.1.3.2 and 7.2.1.4.1 of [11]. IKE with pre-shared keys is required to implement, while IKE with certificates and Kerberized IPsec are both optional to implement.
+
+In the case that Kerberized IPsec is utilized, clause 6.4.5 of [11] defines principal names of various Kerberized services. The first component of a principal name is unique for each type of a Kerberized service. The first component of Policy Server's principal name is specified in 8.2/J.170. The first component of Application Manager's principal name MUST be:
+
+am:<ElementID>
+
+where <ElementID> is defined in 6.4.5 of [11].
+
+In the case that IKE with certificates is utilized, the subject name in a server certificate has the following attribute defined in 8.2.3.4.3 of [11]:
+
+OU=<Sub-System Name>
+
+The value of <Sub-System Name> identifies a server type. The value of <Sub-System Name> for a Policy Server is specified in 8.2/J.170. The value of <Sub-System Name> for an Application Manager MUST be the following 2-character string: am.
+
+## 8.4 Policy Server – RKS Event Message Interface (pkt-mm-4)
+
+The Policy Server – RKS Event Message interface MUST be secured using the IPsec ESP protocol, as specified in 7.3.2 of [11]. The key management for this interface MUST be identical to the one specified for a CMTS-RKS interface in 7.3.3.2 of [11]. IKE with pre-shared keys is required to implement, while IKE with certificates and Kerberized IPsec are both optional to implement.
+
+In the case that Kerberized IPsec is utilized, clause 6.4.5 of [11] defines principal names of various Kerberized services. The first component of a principal name is unique for each type of a Kerberized service. Clause 6.4.5 of [11] already specifies the first component of the RKS's principal name. The first component of Policy Server's principal name is specified in 8.2/J.170.
+
+In the case that IKE with certificates is utilized, the subject name in a server certificate has the following attribute defined in 8.2.3.4.3 of [11]:
+
+OU=<Sub-System Name>
+
+The value of <Sub-System Name> identifies a server type. The value of <Sub-System Name> for an RKS is already specified in 8.2.3.4.3 of [11]. The value of <Sub-System Name> for a Policy Server is specified in 8.2 of [11].
+
+## 8.5 CMTS – RKS Event Message Interface (pkt-mm-5)
+
+The CMTS – RKS Event Message interface MUST be secured using the IPsec ESP protocol, as specified in 7.3.2 of [11]. The key management for this interface is specified in 7.3.3.2 of [11]. IKE with pre-shared keys is required to implement, while IKE with certificates and Kerberized IPsec are both optional to implement.
+
+# 9 Mapping a FlowSpec traffic profile to DOCSIS
+
+A Traffic Profile defines the QoS attributes of the IP flow or the Annex B/J.112 Service Flow to be used in performing authorization, reservation and commit operations. A Traffic Profile can be defined via one of the following methods:
+
+- FlowSpec;
+- DOCSIS Service Class Name;
+- DOCSIS Specific Parameterization.
+
+This clause describes the mapping procedures for deriving the DOCSIS-specific QoS parameters from the various Traffic Profile representations. A Traffic Profile may include the authorization, reservation or commit envelopes. As defined in [3], a FlowSpec consists of a TSPEC and an optional RSpec.
+
+## 9.1 Mapping FlowSpecs to DOCSIS scheduling types
+
+FlowSpecs support two types of services: Controlled Load and Guaranteed. Controlled Load services provide minimum bandwidth guarantees, but not latency/delay guarantees. Guaranteed services provide both bandwidth and latency/delay guarantees. Guaranteed service may be closely approximated through DOCSIS Real-Time Polling and UGS scheduling types. Controlled Load service may be closely approximated through the DOCSIS Best-Effort scheduling type. The FlowSpec service number in the FlowSpec definition distinguishes between Controlled Load and Guaranteed services. Service number 5 indicates the definition is for Controlled Load service, and service number 2 indicates the definition is for Guaranteed service. Further, Controlled Load service contains only the TSPEC token bucket parameters, but not the RSpec. Guaranteed service MUST contain both the TSPEC and the RSpec.
+
+For latency and jitter-sensitive applications such as voice, MPEG video or gaming, one could request Guaranteed service. The CMTS can then use the traffic profile parameters specified in the FlowSpec to select one of the two types of DOCSIS scheduling types that could provide Guaranteed service: RTPS and UGS. For other applications that are not latency sensitive, one could request Controlled Load service which can be used to provide minimum bandwidth guarantees. Table 26 summarizes the choices.
+
+**Table 26/J.179 – Mapping FlowSpecs types**
+
+| DOCSIS scheduling type           | FlowSpec service number | Application example       |
+|----------------------------------|-------------------------|---------------------------|
+| Unsolicited Grant Service (UGS)  | 2 (Guaranteed)          | Voice over IP             |
+| Real-Time Polling Service (RTPS) | 2 (Guaranteed)          | VPN                       |
+| Best Effort (BE)                 | 5 (Controlled Load)     | Best Effort Internet Data |
+
+The general FlowSpec-to-DOCSIS mapping procedure for upstream service flows is as follows:
+
+- Upon receipt of a Gate-Set message with a FlowSpec the CMTS MUST analyse the TSpec Service Header to determine whether Controlled load or Guaranteed service is being requested.
+- If Controlled Load Service, then the CMTS MUST use only the TSpec parameters to resolve the DOCSIS scheduling parameters to define the DOCSIS Traffic Parameters for a DOCSIS Best-Effort Scheduling type.
+- If Guaranteed Service, the CMTS MUST examine the TSpec parameter's values for Reserved Rate (R) and Bucket Rate (r). If the two values are equal, then the CMTS MUST use the TSpec and the RSpec to define the DOCSIS Traffic Parameters for a DOCSIS UGS scheduling type.
+- If the Reserved Rate (R) and Bucket Rate (r) are not equal, then the CMTS MUST use the TSpec and the RSpec to define the DOCSIS Traffic Parameters for a DOCSIS Real-Time Polling scheduling type.
+
+Note that two other types of DOCSIS scheduling types are not mentioned above. These are:
+
+- Unsolicited Grant Service with Activity Detection;
+- Non-Real-Time Polling Service.
+
+If the Application Manager wishes to request either one of these services, it can only do so by using either the Service Class Name or the DOCSIS-specific parameterization method of defining the Traffic Profile.
+
+## 9.2 Mapping FlowSpecs to DOCSIS traffic parameters
+
+The FlowSpec is made up of two parts, the TSpec and the RSpec. The TSpec describes the traffic for the flow, and the RSpec describes the desired service; note that for a controlled load service, the RSpec is not used. The RSpec parameters MUST be specified for a guaranteed service. The CMTS MUST ignore the RSpec parameters for a controlled load service. The RSpec is used to provide latency guarantees for guaranteed services. Please refer to RFCs 2210 [3], 1305 [2], 2211 [4], and 2212 [5] for more information on how these parameters should be used by Application Managers to specify the traffic profile. Note that the IPCablecom Multimedia interpretation of Flowspecs differs from the RFCs in the following respects:
+
+- Guaranteed Service as defined in [5] controls Layer 3 queuing delay (i.e., the delays associated with packet scheduling), whereas in IPCablecom Multimedia we are primarily concerned with controlling the access delay of the DOCSIS MAC layer. Consequently, we reserve bandwidth resources according to the TSpec's *r* parameter rather than the RSpec's *R*.
+- As defined in [4], Controlled Load service defines only a guaranteed minimum rate for a flow. IPCablecom Multimedia's Controlled Load service facilitates definition of the maximum rate for a flow, as well as definition of flows without a guaranteed minimum rate.
+- The Guaranteed Service Slack Term parameter is not needed in IPCablecom Multimedia, so the field is redefined to enable control of DOCSIS polling jitter.
+
+TSpec Parameters:
+
+- Bucket Depth (b), bytes;
+- Bucket Rate (r), bytes/second;
+- Maximum Datagram Size (M), bytes;
+- Minimum Policed Unit (m), bytes;
+- Peak Rate (p), bytes/second.
+
+RSpec Parameters:
+
+- Reserved Rate (R), bytes/second;
+- Slack Term (S), microseconds.
+
+The parameter mapping, roughly approximated, involves the following associations for DOCSIS upstream BE (Best-Effort) and downstream Controlled Load Service Flows. The actual mapping procedure would involve normalizing these parameters to account for Layer 2 and Layer 3 header considerations.
+
+- TSpec Bucket Depth (b)  $\sim=$  DOCSIS Maximum Traffic Burst;
+- TSpec Maximum Datagram Size (M)  $\sim=$  <not required by DOCSIS>;
+- TSpec Minimum Policed Unit (m)  $\sim=$  DOCSIS Assumed Minimum Reserved Rate Packet Size;
+- TSpec Bucket Rate (r)  $\sim=$  DOCSIS Minimum Reserved Rate;
+- TSpec Peak Rate (p)  $\sim=$  DOCSIS Maximum Sustained Rate for Controlled Load service.
+
+For downstream Guaranteed service flows, the RSpec parameters are added to provide latency and reservation guarantees.
+
+- TSpec Bucket Depth (b)  $\sim=$  DOCSIS Maximum Traffic Burst;
+- TSpec Maximum Datagram Size (M)  $\sim=$  <not required by DOCSIS>;
+- TSpec Minimum Policed Unit (m)  $\sim=$  DOCSIS Assumed Minimum Reserved Rate Packet Size;
+- TSpec Bucket Rate (r)  $\sim=$  DOCSIS Minimum Reserved Rate;
+- RSpec Reserved Rate (R)  $\sim=$  DOCSIS Maximum Sustained Rate for Guaranteed service;
+- RSpec Slack Term  $\sim=$  DOCSIS Downstream Latency.
+
+The parameter mapping, roughly approximated, involves the following associations for DOCSIS UGS Service Flows.
+
+- TSpec Bucket Depth (b) = TSpec Maximum Datagram Size (M) = TSpec Minimum Policed Unit (m)  $\sim=$  DOCSIS Unsolicited Grant Size;
+- TSpec Bucket Rate (r) = TSpec Peak Rate (p) = RSpec Reserved Rate (R)  $\sim=$  <not required by DOCSIS>;
+- RSpec Slack Term  $\sim=$  DOCSIS Tolerated Grant Jitter.
+
+Similarly, the following associations apply for DOCSIS Real-Time Polling Service Flows:
+
+- TSpec Bucket Depth (b)  $\sim=$  DOCSIS Maximum Traffic Burst;
+- TSpec Maximum Datagram Size (M)  $\sim=$  <not required by DOCSIS>;
+- TSpec Bucket Rate (r)  $\sim=$  DOCSIS Maximum Sustained Rate for Guaranteed Service;
+- RSpec Reserved Rate (R)  $\sim=$  used to calculate the Polling Interval;
+- RSpec Slack Term  $\sim=$  Tolerated Polling Jitter.
+
+This abstraction model allows standards-based RSVP implementations (as anticipated in Scenarios 2 and 3) to request and receive controlled load or guaranteed service from the network without necessarily requiring DOCSIS-specific info.
+
+In some situations, where the Application Manager and the Policy Server is acutely aware of DOCSIS, it MAY specify the Traffic Profile for the Gate using the DOCSIS Service Class Name or the DOCSIS-specific parameterization format.
+
+Note that there are several DOCSIS Service Flow parameters that cannot be directly resolved from the FlowSpecs; in these cases, the IPCablecom Multimedia Recommendation defines defaults for
+
+those Service Flow parameters. If the Application Manager/Policy Server wishes to set those Service Flow parameters to something other than the defaults specified by this Recommendation, the Application Manager/Policy Server MUST use either the Service Class Names or the DOCSIS-specific parameterization formats to define the traffic profile.
+
+For Guaranteed Service, the Minimum Reserved Rate and the Maximum Sustained Rates are set to the same value, and are based on the Bucket Rate, 'r'. This is because Guaranteed Service provides latency guarantees, and this means a flow cannot be sustained at a rate greater than the rate at which the source has agreed to generate (when the reservation was initially made). A reservation made with a Traffic Profile specifying a Bucket Rate 'r' means that the source will not sustain a traffic flow greater than 'r'. Thus, it would be incorrect to use the Reserved Rate 'R' to represent any DOCSIS sustained rate (either minimum or maximum), in the Guaranteed service case.
+
+For real-time polling Scheduling however, the CMTS uses the Reserved Rate R to calculate the polling interval, so that traffic sources can burst at the rate of R without increasing the delay that the packets experience waiting for a DOCSIS upstream transmission opportunity. Although the traffic source may generate traffic at rate 'R' in this case, the CMTS will ensure the sustained rate does not violate 'r' over time.
+
+For Controlled Load Service, because there are no latency guarantees and because we want to enable one to use the DOCSIS-specific concepts of guaranteed minimum as well as maximum sustained rates, the TSpec Bucket Rate 'r' is mapped to the DOCSIS minimum rate, and the TSpec Peak Rate 'p' is mapped to the DOCSIS Maximum Sustained Rate. If a zero or infinite value is indicated for 'r', then the DOCSIS Minimum Reserved Rate parameter MUST be omitted. If a zero or infinite value is indicated for 'p', then the DOCSIS Maximum Sustained Rate parameter MUST be omitted.
+
+If a syntactic or semantic conflict exists between the DOCSIS RFI specification and this specification the DOCSIS RFI specification MUST take precedence unless otherwise noted.
+
+## 9.3 DOCSIS upstream parameters
+
+For all of the upstream packet size calculations, the following formula must be used unless otherwise specified: The packet PDU MUST be calculated from the first byte following the DOCSIS MAC HCS to the end of the CRC. This value includes the Ethernet header overhead of 18 bytes (6 bytes for source address, 6 bytes for destination address, 2 bytes for length, and 4 bytes for CRC). The value also incorporates DOCSIS MAC layer overhead, including the DOCSIS base header (6 bytes), the UGS extended header (3 bytes), and the BPI+ extended header (5 bytes).
+
+In the equations used in all subsequent clauses, the following variables apply:
+
+ENET = Ethernet overhead (18 or 22-bytes), a default of 18-bytes MUST be used unless otherwise indicated (how the CMTS determines to use 22-bytes is outside the scope of this Recommendation). In the case of a UGS flow, packets using extended Ethernet headers that are not accounted for will result in the packets being dropped (packets exceeding the Grant size must be dropped). In the case of a RTPS flow, packets using extended Ethernet headers that are not accounted for will result in the packets being sent on the primary (best effort) service flow.
+
+DOCSIS = DOCSIS header = 6 bytes
+
+BPI = DOCSIS BPI header = 5 bytes
+
+UGS = DOCSIS UGS extended header = 3 bytes
+
+### 9.3.1 Unsolicited Grant Scheduling (UGS)
+
+Unsolicited Grant Scheduling MUST be used when the Service Number is 2 (Guaranteed), the Peak Rate, Bucket Rate, and the Reserved Rate are all equal, and Maximum Datagram Size is equal to Minimum Policed Unit.
+
+The DOCSIS upstream objects MUST be set as stated below. All service flow quality of service TLV encodings that are not defined here MUST be given their default values as indicated by DOCSIS.
+
+The DOCSIS Unsolicited Grant Size incorporates DOCSIS MAC layer overhead in addition to the packet PDU size calculated using the formula specified in 9.3. The DOCSIS MAC layer overhead includes the DOCSIS base header (6 bytes), the UGS extended header (3 bytes), and optionally the BPI+ extended header (5 bytes).
+
+$$\text{DOCSIS Unsolicited Grant Size} = M + \text{ENET} + \text{DOCSIS} + \text{UGS} + \text{BPI}$$
+
+The example above assumes that BPI+ [12] is enabled.
+
+The DOCSIS Maximum Sustained Traffic Rate and DOCSIS Assumed Minimum Reserved Rate Packet Size parameters MUST NOT be used for upstream flows.
+
+The DOCSIS Grants per Interval parameter MUST be set to 1.
+
+The DOCSIS Nominal Grant Interval parameter MUST be set to the Maximum Datagram Size divided by the Reserved Rate converted to microseconds.
+
+$$\text{DOCSIS Nominal Grant Interval} = M/R \times 1\,000\,000.$$
+
+The DOCSIS Tolerated Grant Jitter parameter MUST be set to Slack Term. If the value is less than the duration of a DOCSIS minislot, then the minislot duration MUST be used instead. If a value of zero is specified, then the default value of 800  $\mu\text{s}$  MUST be used.
+
+The DOCSIS Nominal Polling Interval parameter MUST NOT be specified in the Traffic Profile for UGS service flows. The DOCSIS Tolerated Polling Jitter parameter MUST NOT be specified in the Traffic Profile for UGS service flows.
+
+The DOCSIS Request/Transmission Policy parameter is a bitmask; bits 0-6 and 8 MUST be set for UGS service flows.
+
+### 9.3.2 Real-time polling scheduling
+
+Real-Time Polling Scheduling MUST be used when the Service Number is 2 (Guaranteed Service) and Peak Rate is not equal to Bucket Rate or Maximum Datagram Size is not equal to Minimum Policed Unit.
+
+The DOCSIS upstream objects MUST be set as stated below. All service flow quality of service TLV encodings that are not defined here MUST be given their default values as indicated by DOCSIS.
+
+The DOCSIS Maximum Sustained Traffic Rate parameter is given in bits per second, and includes Ethernet layer overhead. The conversion from IP-specific parameters involves first determining the packetization rate by dividing the Bucket Rate by the Minimum Policed Unit. This value is then multiplied by the packet size, Minimum Policed Unit, including MAC layer overhead, and the entire product is scaled from bytes to bits.
+
+$$\text{DOCSIS Maximum Sustained Traffic Rate} = r/m \times (m + \text{ENET}) \times 8$$
+
+The DOCSIS Maximum Traffic Burst parameter MUST be set to the greater of:
+
+- 1) Bucket Depth including the Ethernet overhead calculated using the Minimum Policed Unit; or
+
+2) the DOCSIS specified minimum value of 1522.
+
+$$\text{DOCSIS Maximum Traffic Burst} = \max ( (\text{Bucket Depth} / m) \times (m + \text{ENET}), 1522)$$
+
+The DOCSIS Minimum Reserved Traffic Rate parameter is the same as the DOCSIS Maximum Sustained Traffic Rate.
+
+$$\text{DOCSIS Minimum Reserved Traffic Rate} = r/m \times (m + \text{ENET}) \times 8$$
+
+The DOCSIS Request/Transmission Policy parameter is a bitmask; the recommended default value should be 0x1F.
+
+The DOCSIS Nominal Polling Interval parameter MUST be set to Minimum Policed Unit divided by Reserved Rate converted to microseconds.
+
+$$\text{DOCSIS Nominal Polling Interval} = m/R \times 1\,000\,000$$
+
+The DOCSIS Tolerated Polling Jitter parameter MUST be set to Slack Term. If the value is non-zero but less than the duration of a minislot, then it MUST be set to the duration of a minislot. If a value of zero is specified, then the DOCSIS Tolerated Polling Jitter must default to a value of 800  $\mu\text{s}$ .
+
+$$\text{DOCSIS Nominal Polling Jitter} = S$$
+
+### 9.3.3 Best effort scheduling
+
+Best Effort Scheduling MUST be used when the Service Number is 5 (Controlled-Load).
+
+The DOCSIS upstream objects MUST be set as stated below. All service flow quality of service TLV encodings that are not defined here MUST be given their default values as indicated by DOCSIS.
+
+The DOCSIS Traffic Priority MUST be set to 5.
+
+The DOCSIS Maximum Sustained Traffic Rate parameter is given in bits per second, including Ethernet layer overhead. The conversion from IP-specific parameters involves first determining the packetization rate by dividing the Peak Rate by the Minimum Policed Unit. This value is then multiplied by the packet size, Minimum Policed Unit, amended to include Ethernet layer overhead, and the entire product is scaled from bytes to bits. The DOCSIS Maximum Sustained Traffic Rate MUST be converted from the Minimum Policed Unit.
+
+$$\text{DOCSIS Maximum Sustained Traffic Rate} = p/m \times (m + \text{ENET}) \times 8$$
+
+The DOCSIS Maximum Traffic Burst parameter MUST be set to the greater of:
+
+- 1) Bucket Depth including the Ethernet overhead calculated using the Minimum Policed Unit; or
+- 2) the DOCSIS specified minimum value of 1522.
+
+$$\text{DOCSIS Maximum Traffic Burst} = \max ( (\text{Bucket Depth} / m) \times (m + \text{ENET}), 1522)$$
+
+The DOCSIS Minimum Reserved Traffic Rate parameter is calculated in a manner similar to the DOCSIS Maximum Sustained Traffic Rate, except that instead of using the Peak Rate parameter, the Bucket Rate is used.
+
+$$\text{DOCSIS Minimum Reserved Traffic Rate} = r/m \times (m + \text{ENET}) \times 8$$
+
+### 9.3.4 Upstream packet classification encodings
+
+#### 9.3.4.1 DOCSIS upstream packet classification requests
+
+The DOCSIS upstream objects MUST be set as stated below. All classification TLV encodings that are not defined here MUST be given their default values as indicated by DOCSIS.
+
+The DOCSIS Classifier Identifier parameter MUST be used.
+
+The DOCSIS Service Flow Identifier parameter MUST be used.
+
+The DOCSIS Rule Priority parameter MUST be set to the Priority value in the Classifier object.
+
+The DOCSIS Classification Activation State parameter MUST be set to active (1) when the Gate utilizing the service flow is committed, and for all the other cases it MUST be set to inactive (0).
+
+The DOCSIS Dynamic Service Change Action MAY use the DSC Add Classifier (0), DSC Replace Classifier (1) and DSC Delete Classifier (2) operations per the DOCSIS RFI Recommendation.
+
+The DOCSIS IP Protocol parameter MUST be set to the Protocol ID value specified in the Classifier object if the value is non-zero, and omitted otherwise.
+
+The DOCSIS IP Source Address parameter MUST be set to the same address as that in the Classifier object, so long as a non-zero value is provided. If the address specified in the Classifier object is zero, this parameter MUST be omitted.
+
+The DOCSIS IP Source Mask parameter MUST be omitted.
+
+The DOCSIS IP Source Port Start and DOCSIS IP Source Port End parameters MUST be set to the same port value as the Classifier object so long as a non-zero value is provided. If the value specified in the Classifier object is zero, both the DOCSIS IP Source Port Start and DOCSIS IP Source Port End parameters MUST be omitted.
+
+The DOCSIS IP Destination Address parameter MUST be set to the same address as that in the Classifier object, so long as a non-zero value is provided. If the address specified in the Classifier object is zero, this parameter MUST be omitted.
+
+The DOCSIS IP Destination Mask parameter MUST be omitted.
+
+The DOCSIS IP Destination Port Start and DOCSIS IP Destination Port End parameters MUST be set to the same port value as the Classifier object, so long as a non-zero value is provided. If the value specified in the Classifier object is zero, both the DOCSIS IP Destination Port Start and DOCSIS IP Destination Port End parameters MUST be omitted.
+
+The DOCSIS Ethernet LLC Packet Classification Encodings parameters MUST be omitted.
+
+The DOCSIS 802.1P/Q Packet Classification Encodings parameters MUST be omitted.
+
+## **9.4 DOCSIS downstream parameters**
+
+### **9.4.1 Downstream QoS encodings for guaranteed service**
+
+The DOCSIS downstream service flow quality-of-service TLV encodings MUST be set as stated below. All service flow quality of service TLV encodings that are not defined here MUST be given their default values as indicated by DOCSIS.
+
+The downstream DOCSIS parameters are calculated using DOCSIS MAC header from the byte following the HCS to the end of the CRC. This value includes the Ethernet header overhead.
+
+Based on this overhead, the DOCSIS Assumed Minimum Reserved Rate Packet Size parameter MUST be calculated as:
+
+$$\text{DOCSIS Assumed Minimum Reserved Rate Packet Size} = m + \text{ENET}$$
+
+The DOCSIS Maximum Sustained Traffic Rate parameter is given in bits per second, including MAC layer overhead. The conversion from IP-specific parameters involves first determining the packetization rate by dividing the Bucket Rate by the Minimum Policed Unit. This value is then multiplied by the packet size, Minimum Policed Unit, amended to include MAC layer overhead, and the entire product is scaled from bytes to bits. The DOCSIS Maximum Sustained Traffic Rate MUST be calculated as:
+
+$$\text{DOCSIS Maximum Sustained Traffic Rate} = r/m \times (m + \text{ENET}) \times 8$$
+
+The DOCSIS Minimum Reserved Traffic Rate is equal to the DOCSIS Maximum Sustained Traffic Rate.
+
+Note that the DOCSIS Maximum Sustained Traffic Rate and the DOCSIS Minimum Reserved Traffic Rate are calculated slightly differently in IPCablecom Multimedia and IPCablecom DQoS. IPCablecom Multimedia is based on  $r$  and IPCablecom DQoS is based on  $p$ . This is due to the fact that in DQoS  $r = p$ , while in Multimedia, these values differ (in which case  $r$  is the proper rate value to use).
+
+The DOCSIS Maximum Traffic Burst parameter MUST be set to the greater of:
+
+- 1) Bucket Depth including the DOCSIS overhead calculated using the Minimum Policed Unit; or
+- 2) the DOCSIS specified minimum value of 1522.
+
+$$\text{DOCSIS Maximum Traffic Burst} = \max ( (\text{Bucket Depth} / m) \times (m + \text{ENET}), 1522)$$
+
+The DOCSIS Traffic Priority parameter MUST be set to 5.
+
+The DOCSIS Downstream Latency parameter MUST be set to Slack Term, if Slack Term is non-zero. If Slack Term is zero, this parameter MUST NOT be populated.
+
+### 9.4.2 Downstream QoS encodings for controlled load service
+
+The DOCSIS downstream service flow quality of service TLV encodings MUST be set as stated below. All service flow quality of service TLV encodings that are not defined here MUST be given their default values as indicated by DOCSIS.
+
+The downstream DOCSIS parameters are calculated using the DOCSIS MAC header from the byte following the HCS to the end of the CRC. This value includes the Ethernet header overhead.
+
+Based on this overhead, the DOCSIS Assumed Minimum Reserved Rate Packet Size parameter MUST be calculated as:
+
+$$\text{DOCSIS Assumed Minimum Reserved Rate Packet Size} = m + \text{ENET}$$
+
+The DOCSIS Maximum Sustained Traffic Rate parameter is given in bits per second, including MAC layer overhead. The conversion from IP-specific parameters involves first determining the packetization rate by dividing the Peak Rate by the Minimum Policed Unit. This value is then multiplied by the packet size, Minimum Policed Unit, amended to include MAC layer overhead, and the entire product is scaled from bytes to bits. The DOCSIS Maximum Sustained Traffic Rate MUST be calculated as:
+
+$$\text{DOCSIS Maximum Sustained Traffic Rate} = p/m \times (m + \text{ENET}) \times 8$$
+
+The DOCSIS Minimum Reserved Traffic Rate parameter is calculated in a manner similar to the DOCSIS Maximum Sustained Traffic Rate, except that instead of using the Peak Rate, the Bucket Rate is used.
+
+$$\text{DOCSIS Minimum Reserved Traffic Rate} = r/m \times (m + \text{ENET}) \times 8$$
+
+The DOCSIS Maximum Traffic Burst parameter MUST be set to the greater of:
+
+- 1) Bucket Depth including the DOCSIS overhead calculated using the Maximum Datagram Size; or
+- 2) the DOCSIS specified minimum value of 1522.
+
+$$\text{DOCSIS Maximum Traffic Burst} = \max ( (\text{Bucket Depth} / M) \times (M + \text{ENET}), 1522)$$
+
+The DOCSIS Traffic Priority parameter MUST be set to 5.
+
+The DOCSIS Downstream Latency parameter MUST NOT be populated.
+
+### **9.4.3 Downstream packet classification encodings**
+
+#### **9.4.3.1 DOCSIS downstream packet classification requests**
+
+The DOCSIS downstream classification objects MUST be set as stated below. All classification TLV encodings that are not defined here MUST be given their default values as indicated by DOCSIS.
+
+The DOCSIS Classifier Identifier parameter MUST be used.
+
+The DOCSIS Service Flow Identifier parameter MUST be used.
+
+The DOCSIS Rule Priority parameter MUST be set to Priority value specified in the Classifier object.
+
+The DOCSIS Classification Activation State parameter MUST be set to active (1) when the Gate utilizing the service flow is committed, and for all the other cases it MUST be set to inactive (0).
+
+The DOCSIS Dynamic Service Change Action MAY use the DSC Add Classifier (0), DSC Replace Classifier (1) and DSC Delete Classifier (2) operations per the DOCSIS RFI Recommendation.
+
+The DOCSIS IP Protocol parameter MUST be set to the Protocol ID value specified in the Classifier object if the value is non-zero and omitted otherwise.
+
+The DOCSIS IP Source Address parameter MUST be set to the source address provided in the Classifier object, so long as a non-zero value is provided. If the address specified in the Classifier object is zero, this parameter MUST be omitted.
+
+The DOCSIS IP Source Mask parameter MUST be omitted.
+
+The DOCSIS IP Source Port Start and DOCSIS IP Source Port End parameters MUST be set to the same port value as the Classifier object, so long as a non-zero value is provided. If the value specified in the Classifier object is zero, both the DOCSIS IP Source Port Start and DOCSIS IP Source Port End parameters MUST be omitted.
+
+The DOCSIS IP Destination Address parameter MUST be set to the destination address provided in the Classifier object, so long as a non-zero value is provided. If the address specified in the Classifier object is zero, this parameter MUST be omitted.
+
+The DOCSIS IP Destination Mask parameter MUST be omitted.
+
+The DOCSIS IP Destination Port Start and DOCSIS IP Destination Port End parameters MUST be set to the same port value as the Classifier object, so long as a non-zero value is provided. If the value specified in the Classifier object is zero, both the DOCSIS IP Destination Port Start and DOCSIS IP Destination Port End parameters MUST be omitted.
+
+The DOCSIS Ethernet LLC Packet Classification Encodings MUST be omitted.
+
+The DOCSIS 802.1P/Q Packet Classification Encodings MUST be omitted.
+
+# **10 Message flows**
+
+This clause provides two interaction scenarios between the various network elements previously introduced in this Recommendation. The first interaction outlines at a relatively high-level the basic message exchanges that take place within the IPCablecom Multimedia framework in order to authorize, reserve and commit access network resources under Scenario 1. The second interaction provides a very detailed breakout of each message and attribute involved in the IPCablecom Multimedia QoS and EM interfaces.
+
+## 10.1 Basic message sequence
+
+![Sequence diagram illustrating the basic message sequence between a Client, CM, Application Manager, CM/TS, and Policy Server. The diagram shows eight numbered message exchanges: 1) Client to Application Manager, 2) Application Manager to Policy Server, 3) Policy Server to CM/TS, 4) CM to CM/TS, 5) CM/TS to CM, 6) CM/TS to Policy Server, 7) Policy Server to Application Manager, and 8) Application Manager to Client. The diagram includes labels for 'Application manager 'n'', 'Application Manager 1', 'Policy server 'm'', 'Policy server 1', and 'J.179_F08'.](7c3ecd751b69a0fc7b08633a84822f42_img.jpg)
+
+```
+
+sequenceDiagram
+    participant Client
+    participant CM
+    participant AM as Application Manager 1
+    participant AM_n as Application manager 'n'
+    participant CM/TS
+    participant PS as Policy server 1
+    participant PS_m as Policy server 'm'
+
+    Note right of AM_n: Application manager 'n'
+    Note right of PS_m: Policy server 'm'
+
+    Client->>AM: 1
+    AM-->>Client: 8
+    AM->>PS: 2
+    PS-->>AM: 7
+    PS->>CM/TS: 3
+    CM/TS-->>PS: 6
+    CM->>CM/TS: 5
+    CM/TS-->>CM: 4
+  
+```
+
+Sequence diagram illustrating the basic message sequence between a Client, CM, Application Manager, CM/TS, and Policy Server. The diagram shows eight numbered message exchanges: 1) Client to Application Manager, 2) Application Manager to Policy Server, 3) Policy Server to CM/TS, 4) CM to CM/TS, 5) CM/TS to CM, 6) CM/TS to Policy Server, 7) Policy Server to Application Manager, and 8) Application Manager to Client. The diagram includes labels for 'Application manager 'n'', 'Application Manager 1', 'Policy server 'm'', 'Policy server 1', and 'J.179\_F08'.
+
+Figure 8/J.179 – Basic message sequence
+
+- 1) Client issues a session setup request to the Application Manager via Application Layer signalling. The client may authenticate itself to the Application Manager during this step.
+- 2) Before the Application Manager activates the session, the Application Manager issues a Gate-Set (in a COPS DECISION message) and sends it to Policy Server in order to determine if the session setup request should be allowed to proceed. Message includes:
+  - i) AMID;
+  - ii) SubscriberID;
+  - iii) TransactionID;
+  - iv) Classifier;
+  - v) Traffic Profile for Flow;
+  - vi) Gate Spec.
+- 3) Upon receiving the request, the Policy Server checks the request against the policy rules and if the request is approved, sends a Gate-Set to the CM/TS. Message includes:
+  - i) AMID;
+  - ii) SubscriberID;
+  - iii) TransactionID;
+  - iv) Classifier;
+  - v) Traffic Profile for Flow (Authorized, Reserved and Committed);
+  - vi) Gate Spec.
+- 4) CM/TS uses the classifier and Traffic Profile information to trigger the activation of the flow by issuing the appropriate DOCSIS DSx messages.
+- 5) CM acknowledges with the appropriate DSx messaging.
+- 6) CM/TS issues a Gate-Set-Ack to the Policy Server in response to the Gate-Set message received in Step 3. Message includes:
+  - i) AMID;
+  - ii) TransactionID;
+  - iii) GateID;
+  - iv) Subscriber ID.
+
+- 7) In response the Policy Server will generate a Gate-Set-Ack to the AM; this tells the AM that the Policy Request has been admitted and the client's request can proceed, and the necessary resources in the underlying network have been reserved. Message includes:
+  - i) AMID;
+  - ii) TransactionID;
+  - iii) GateID;
+  - iv) Subscriber ID.
+- 8) The Application Manager, upon receiving the Gate-Set-Ack will inform the client that the session establishment can proceed.
+
+## 10.2 Detailed message sequence
+
+![Sequence diagram showing message exchanges between Client, CM, CM/TS, PS, RKS, and AM for session setup and teardown.](4cf20a1cc0755dff37937135bda4e2c6_img.jpg)
+
+The diagram illustrates a detailed message sequence for a session, divided into two main parts: session setup and session teardown, separated by a 'Session in progress' phase.
+
+**Participants:** Client, CM, CM/TS, PS, RKS, AM.
+
+**Session Setup:**
+
+- (1) Application signalling: Client → AM
+- (2) Gate-Set: AM → PS
+- (3) Gate-Set: PS → CM/TS
+- (4) DSA-REQ: CM/TS → CM
+- (5) DSA-RSP: CM → CM/TS
+- (6a) DSA-ACK: CM/TS → CM
+- (6b) Gate-Set-Ack: CM/TS → PS
+- (6c) QoS Reserve: CM/TS → RKS
+- (6d) QoS Commit: CM/TS → RKS
+- (7a) QoS Reserve Ack: RKS → CM/TS
+- (7b) QoS Commit Ack: RKS → CM/TS
+- (7c) Gate-Set-Ack: PS → AM
+- (7d) Policy Request: PS → RKS
+- (8) Policy Request Ack: RKS → PS
+- (9) Application signalling: AM → Client
+
+**Session in progress**
+
+**Session Teardown:**
+
+- (10) Application signalling: Client → AM
+- (11) Gate-Delete: AM → PS
+- (12) Gate-Delete: PS → CM/TS
+- (13) DSD-REQ: CM/TS → CM
+- (14) DSD-RSP: CM → CM/TS
+- (15a) Gate-Del-Ack: CM/TS → PS
+- (15b) QoS Release: CM/TS → RKS
+- (16a) QoS Release Ack: RKS → CM/TS
+- (16b) Gate-Del-Ack: PS → AM
+- (16c) Policy Delete: PS → RKS
+- (17) Policy Delete Ack: RKS → PS
+
+J.179\_F09
+
+Sequence diagram showing message exchanges between Client, CM, CM/TS, PS, RKS, and AM for session setup and teardown.
+
+**Figure 9/J.179 – Detailed message sequence**
+
+The pages that follow describe in detail the messages that are being exchanged in an example IPCablecom Multimedia session. The bandwidth numbers are purely examples, and do not correlate to any particular service. Only the upstream access network resources are being reserved and committed for clarity. Also, BPI-related TLVs have been left out of the DOCSIS messages for clarity.
+
+- 1) The client initializes the session by querying an Application Manager for the necessary resources to use the application. An example of this would be a software-based video game,
+
+asking for resources to play an online game. This signalling is out of the scope of this Recommendation.
+
+- 2) After receiving the application signalling from the client, the Application Manager issues a Gate-Set to the Policy Server, requesting the needed resources for this session.
+
+| 0                                                         |                        | 1                                 |  | 2                      |  | 3 |  |  |  |  |  |  |  |
+|-----------------------------------------------------------|------------------------|-----------------------------------|--|------------------------|--|---|--|--|--|--|--|--|--|
+| COPS Header                                               |                        |                                   |  |                        |  |   |  |  |  |  |  |  |  |
+| Version<br>0x1                                            | Flags<br>0x0           | Op-Code<br>0x02                   |  | Client-Type<br>0x800A  |  |   |  |  |  |  |  |  |  |
+| Message Length<br>0x00000088                              |                        |                                   |  |                        |  |   |  |  |  |  |  |  |  |
+| COPS Handle Object                                        |                        |                                   |  |                        |  |   |  |  |  |  |  |  |  |
+| Length<br>0x0008                                          |                        | C-Num<br>0x01                     |  | C-Type<br>0x01         |  |   |  |  |  |  |  |  |  |
+| Handle<br>0x00001234                                      |                        |                                   |  |                        |  |   |  |  |  |  |  |  |  |
+| COPS Context Object                                       |                        |                                   |  |                        |  |   |  |  |  |  |  |  |  |
+| Length<br>0x0008                                          |                        | C-Num<br>0x02                     |  | C-Type<br>0x01         |  |   |  |  |  |  |  |  |  |
+| Request Type (R-Type)<br>0x0008 (Configuration Request)   |                        | Message Type (M-Type)<br>0x0000   |  |                        |  |   |  |  |  |  |  |  |  |
+| COPS Decision Flag Object                                 |                        |                                   |  |                        |  |   |  |  |  |  |  |  |  |
+| Length<br>0x0008                                          |                        | C-Num<br>0x06                     |  | C-Type<br>0x01         |  |   |  |  |  |  |  |  |  |
+| Command Code<br>0x0001 (Install Configuration)            |                        | Flags<br>0x0000                   |  |                        |  |   |  |  |  |  |  |  |  |
+| COPS Decision Client-Specific Decision Data Object Header |                        |                                   |  |                        |  |   |  |  |  |  |  |  |  |
+| Length<br>0x00A0                                          |                        | C-Num<br>0x06                     |  | C-Type<br>0x04         |  |   |  |  |  |  |  |  |  |
+| Multimedia TransactionID Object                           |                        |                                   |  |                        |  |   |  |  |  |  |  |  |  |
+| Length<br>0x0008                                          |                        | S-Num<br>0x01                     |  | S-Type<br>0x01         |  |   |  |  |  |  |  |  |  |
+| TransactionID<br>0x9999                                   |                        | Gate Command<br>0x0004 (Gate-Set) |  |                        |  |   |  |  |  |  |  |  |  |
+| Multimedia AMID Object                                    |                        |                                   |  |                        |  |   |  |  |  |  |  |  |  |
+| Length<br>0x0008                                          |                        | S-Num<br>0x02                     |  | S-Type<br>0x01         |  |   |  |  |  |  |  |  |  |
+| AMID<br>0x00005678                                        |                        |                                   |  |                        |  |   |  |  |  |  |  |  |  |
+| Multimedia SubscriberID Object                            |                        |                                   |  |                        |  |   |  |  |  |  |  |  |  |
+| Length<br>0x0008                                          |                        | S-Num<br>0x03                     |  | S-Type<br>0x01         |  |   |  |  |  |  |  |  |  |
+| SubscriberID<br>0x01010101                                |                        |                                   |  |                        |  |   |  |  |  |  |  |  |  |
+| Multimedia GateSpec Object                                |                        |                                   |  |                        |  |   |  |  |  |  |  |  |  |
+| Length<br>0x0010                                          |                        | S-Num<br>0x05                     |  | S-Type<br>0x01         |  |   |  |  |  |  |  |  |  |
+| Flags<br>0x01                                             | DSCP/TOS Field<br>0x00 | DSCP/TOS Mask<br>0x00             |  | SessionClassID<br>0x00 |  |   |  |  |  |  |  |  |  |
+| Timer T1<br>0x00C8 (200 seconds)                          |                        | Timer T2<br>0x012C (300 seconds)  |  |                        |  |   |  |  |  |  |  |  |  |
+| Timer T3<br>0x003C (60 seconds)                           |                        | Timer T4<br>0x001E (30 seconds)   |  |                        |  |   |  |  |  |  |  |  |  |
+
+| 0                                                                                   | 1                           | 2                          | 3                     |
+|-------------------------------------------------------------------------------------|-----------------------------|----------------------------|-----------------------|
+| Multimedia FlowSpec Object                                                          |                             |                            |                       |
+| Length<br>0x0024                                                                    |                             | S-Num<br>0x07              | S-Type<br>0x01        |
+| Envelope<br>0x07                                                                    | Service Number<br>0x02      | Reserved                   | Reserved              |
+| Combined Authorized Reserved and Committed Envelopes                                |                             |                            |                       |
+| Token Bucket Rate [r] (encoded as IEEE floating point)<br>0x461C4000 (10 000 bit/s) |                             |                            |                       |
+| Token Bucket Size [b] (encoded as IEEE floating point)<br>0x43480000 (200 bytes)    |                             |                            |                       |
+| Peak Data Rate [p] (encoded as IEEE floating point)<br>0x461C4000 (10 000 bit/s)    |                             |                            |                       |
+| Minimum Policed Unit [m]<br>0x000000C8 (200 bytes)                                  |                             |                            |                       |
+| Maximum Packet Size [M]<br>0x000000C8 (200 bytes)                                   |                             |                            |                       |
+| Rate [R] (encoded as IEEE floating point)<br>0x461C4000 (10 000 bit/s)              |                             |                            |                       |
+| Slack Term [S]<br>0x00000320 (800 µs)                                               |                             |                            |                       |
+| ⋮                                                                                   |                             |                            | ⋮                     |
+| Multimedia Classifier Object                                                        |                             |                            |                       |
+| Length<br>0x0018                                                                    |                             | S-Num<br>0x06              | S-Type<br>0x01        |
+| Reserved                                                                            | ProtocolID<br>0x11 (17 UDP) | DSCP/TOS Field<br>0x00     | DSCP/TOS Mask<br>0x00 |
+| Source IP Address<br>0x01010101                                                     |                             |                            |                       |
+| Destination IP Address<br>0x02020202                                                |                             |                            |                       |
+| Source Port<br>0x1234                                                               |                             | Destination Port<br>0x9876 |                       |
+| Priority<br>0x0040 (64)                                                             |                             | Reserved                   |                       |
+
+- 3) After the PS receives the Gate-Set from the Application Manager, it checks to see if the request is authorized, and if so, sends a Gate-Set to the CMTS.
+
+| 0                                                       | 1            | 2                               | 3                     |
+|---------------------------------------------------------|--------------|---------------------------------|-----------------------|
+| COPS Header                                             |              |                                 |                       |
+| Version<br>0x1                                          | Flags<br>0x0 | Op-Code<br>0x02                 | Client-Type<br>0x800A |
+| Message Length<br>0x000000B4                            |              |                                 |                       |
+| COPS Handle Object                                      |              |                                 |                       |
+| Length<br>0x0008                                        |              | C-Num<br>0x01                   | C-Type<br>0x01        |
+| Handle<br>0x00005678                                    |              |                                 |                       |
+| COPS Context Object                                     |              |                                 |                       |
+| Length<br>0x0008                                        |              | C-Num<br>0x02                   | C-Type<br>0x01        |
+| Request Type (R-Type)<br>0x0008 (Configuration Request) |              | Message Type (M-Type)<br>0x0000 |                       |
+
+| 0                                                                                   | 1                      | 2                                 | 3                      |
+|-------------------------------------------------------------------------------------|------------------------|-----------------------------------|------------------------|
+| COPS Decision Flags Object                                                          |                        |                                   |                        |
+| Length<br>0x0008                                                                    |                        | C-Num<br>0x06                     | C-Type<br>0x01         |
+| Command Code<br>0x0001 (Install Configuration)                                      |                        | Flags<br>0x0000                   |                        |
+| COPS Decision Client Specific Decision Data Object Header                           |                        |                                   |                        |
+| Length<br>0x00CC                                                                    |                        | C-Num<br>0x06                     | C-Type<br>0x04         |
+| Multimedia TransactionID Object                                                     |                        |                                   |                        |
+| Length<br>0x0008                                                                    |                        | S-Num<br>0x01                     | S-Type<br>0x01         |
+| TransactionID<br>0x0001                                                             |                        | Gate Command<br>0x0004 (Gate-Set) |                        |
+| Multimedia AMID Object                                                              |                        |                                   |                        |
+| Length<br>0x0008                                                                    |                        | S-Num<br>0x02                     | S-Type<br>0x01         |
+| AMID<br>0x00005678                                                                  |                        |                                   |                        |
+| Multimedia SubscriberID Object                                                      |                        |                                   |                        |
+| Length<br>0x0008                                                                    |                        | S-Num<br>0x03                     | S-Type<br>0x01         |
+| SubscriberID<br>0x01010101                                                          |                        |                                   |                        |
+| Multimedia GateSpec Object                                                          |                        |                                   |                        |
+| Length<br>0x0010                                                                    |                        | S-Num<br>0x05                     | S-Type<br>0x01         |
+| Direction<br>0x01                                                                   | DSCP/TOS Field<br>0x00 | DSCP/TOS Mask<br>0x00             | SessionClassID<br>0x00 |
+| Timer T1<br>0x00C8 (200 seconds)                                                    |                        | Timer T2<br>0x012C (300 seconds)  |                        |
+| Timer T3<br>0x003C (60 seconds)                                                     |                        | Timer T4<br>0x001E (30 seconds)   |                        |
+| Multimedia FlowSpec Object                                                          |                        |                                   |                        |
+| Length<br>0x0024                                                                    |                        | S-Num<br>0x07                     | S-Type<br>0x01         |
+| Envelope<br>0x07                                                                    | Service Number<br>0x02 | Reserved                          | Reserved               |
+| Combined Authorized Reserved and Committed Envelopes                                |                        |                                   |                        |
+| Token Bucket Rate [r] (encoded as IEEE floating point)<br>0x461C4000 (10 000 bit/s) |                        |                                   |                        |
+| Token Bucket Size [b] (encoded as IEEE floating point)<br>0x43480000 (200 Bytes)    |                        |                                   |                        |
+| Peak Data Rate [p] (encoded as IEEE floating point)<br>0x461C4000 (10 000 bit/s)    |                        |                                   |                        |
+| Minimum Policed Unit [m]<br>0x000000C8 (200 Bytes)                                  |                        |                                   |                        |
+| Maximum Packet Size [M]<br>0x000000C8 (200 Bytes)                                   |                        |                                   |                        |
+| Rate [R] (encoded as IEEE floating point)<br>0x461C4000 (10 000 bit/s)              |                        |                                   |                        |
+| Slack Term [S]<br>0x00000320 (800 µs)                                               |                        |                                   |                        |
+
+| 0                                                         | 1                  | 2                          | 3                     |  |  |
+|-----------------------------------------------------------|--------------------|----------------------------|-----------------------|--|--|
+| Multimedia Classifier Object                              |                    |                            |                       |  |  |
+| Length<br>0x0018                                          |                    | S-Num<br>0x06              | S-Type<br>0x01        |  |  |
+| Reserved                                                  | ProtocolID<br>0x11 | DSCP/TOS Field<br>0x00     | DSCP/TOS Mask<br>0x00 |  |  |
+| Source IP Address<br>0x01010101                           |                    |                            |                       |  |  |
+| Destination IP Address<br>0x02020202                      |                    |                            |                       |  |  |
+| Source Port<br>0x1234                                     |                    | Destination Port<br>0x9876 |                       |  |  |
+| Priority<br>0x0040 (64)                                   |                    | Reserved                   |                       |  |  |
+| Multimedia Event Generation Info Object                   |                    |                            |                       |  |  |
+| Length<br>0x002C                                          |                    | S-Num<br>0x08              | S-Type<br>0x01        |  |  |
+| Primary RKS Address<br>0x03030303                         |                    |                            |                       |  |  |
+| Primary RKS Port<br>0x1111                                |                    | Reserved                   |                       |  |  |
+| Secondary RKS Address<br>0x04040404                       |                    |                            |                       |  |  |
+| Secondary RKS Port<br>0x1111                              |                    | Reserved                   |                       |  |  |
+| BCID<br>0x3e4812082020202020313436302d303530303000003db77 |                    |                            |                       |  |  |
+| -----                                                     |                    |                            |                       |  |  |
+| -----                                                     |                    |                            |                       |  |  |
+| -----                                                     |                    |                            |                       |  |  |
+| -----                                                     |                    |                            |                       |  |  |
+| -----                                                     |                    |                            |                       |  |  |
+
+- 4) If CMTS admission control succeeds, the CMTS will initiate reserving and committing the access network resources by issuing a DSA to the Cable Modem.
+
+| 0                        | 1                       | 2                           | 3              |
+|--------------------------|-------------------------|-----------------------------|----------------|
+| MAC Management Header    |                         |                             |                |
+| -----                    |                         |                             |                |
+| -----                    |                         |                             |                |
+| -----                    |                         |                             |                |
+| -----                    |                         |                             |                |
+| TransactionID<br>0x0007  |                         | US Service Flow<br>0x18     | Length<br>0x29 |
+| Service Flow ID<br>0x02  | Length<br>0x04          | Value<br>0x0000             |                |
+| Value (cont.)<br>0001    |                         | Service ID<br>0x03          | Length<br>0x02 |
+| Value<br>0x0001          |                         | QoS Param Set<br>0x06       | Length<br>0x01 |
+| Value<br>0x06 (Ad.+Act.) | Scheduling Type<br>0x0F | Length<br>0x01              | Value<br>0x06  |
+| UGS Size<br>0x13         | Length<br>0x02          | Value<br>0x00E8 (232 Bytes) |                |
+
+| 0                                 | 1                         | 2                           | 3                         |
+|-----------------------------------|---------------------------|-----------------------------|---------------------------|
+| Nom. Grant Int.<br>0x14           | Length<br>0x04            | Value<br>0x0000             |                           |
+| Value (cont.)<br>4E20 (20 000 µs) |                           | Grants Per Interval<br>0x16 | Length<br>0x01            |
+| Value<br>0x01                     | RX/TX Policy<br>0x10      | Length<br>0x04              | Value<br>0x00             |
+| Value (cont.)<br>00017F           |                           |                             | Tol. Grant Jitter<br>0x15 |
+| Length<br>0x04                    | Value<br>0x000003         |                             |                           |
+| Value (cont.)<br>20 (800 µs)      | US Pkt. Clfr.<br>0x16     | Length<br>0x02B             | Clfr. ID<br>0x02          |
+| Length<br>0x02                    | Value<br>0x0001           |                             | Service Flow ID<br>0x04   |
+| Length<br>0x04                    | Value<br>0x000000         |                             |                           |
+| Value (cont.)<br>01               | Rule Priority<br>0x05     | Length<br>0x01              | Value<br>0x40             |
+| Clfr. Act. State<br>0x06          | Length<br>0x01            | Value<br>0x01 (Active)      | IP Pkt Clfr 0x09          |
+| Length<br>0x001A                  | IP Protocol<br>0x02       | Length<br>0x02              | Value<br>0x00             |
+| Value (cont.)<br>11 (17 UDP)      | IP Src. Addr<br>0x03      | Length<br>0x04              | Value<br>0x01             |
+| Value (cont.)<br>010101           | IP Src Port Start<br>0x07 |                             |                           |
+| Length<br>0x02                    | Value<br>0x1234           | IP Src Port End<br>0x08     |                           |
+| Length<br>0x02                    | Value<br>0x1234           | IP Dest Port Start<br>0x09  |                           |
+| Length<br>0x02                    | Value<br>0x9876           | IP Dest Port End<br>0x0A    |                           |
+| Length<br>0x02                    | Value<br>0x9876           |                             |                           |
+
+5) The CM responds to the CMTS with a DSA-RSP.
+
+| 0                       | 1 | 2                     | 3 |
+|-------------------------|---|-----------------------|---|
+| MAC Management Header   |   |                       |   |
+| -----                   |   |                       |   |
+| -----                   |   |                       |   |
+| -----                   |   |                       |   |
+| -----                   |   |                       |   |
+| TransactionID<br>0x0007 |   | Confirm. Code<br>0x00 |   |
+
+6a) The CMTS completes the transaction with a DSA-ACK.
+
+| 0                       | 1 | 2                     | 3 |
+|-------------------------|---|-----------------------|---|
+| MAC Management Header   |   |                       |   |
+| -----                   |   |                       |   |
+| -----                   |   |                       |   |
+| -----                   |   |                       |   |
+| -----                   |   |                       |   |
+| TransactionID<br>0x0007 |   | Confirm. Code<br>0x00 |   |
+
+- 6b) Once a DSA-RSP is received by the CMTS from the CM confirming a successful transaction, the CMTS will send a Gate-Set-Ack to the Policy Server.
+
+| 0                                        | 1            | 2                                     | 3                     |
+|------------------------------------------|--------------|---------------------------------------|-----------------------|
+| COPS Header                              |              |                                       |                       |
+| Version<br>0x1                           | Flags<br>0x1 | Op-Code<br>0x03                       | Client-Type<br>0x800A |
+| Message Length<br>0x0000003C             |              |                                       |                       |
+| COPS Handle Object                       |              |                                       |                       |
+| Length<br>0x0008                         |              | C-Num<br>0x01                         | C-Type<br>0x01        |
+| Handle<br>0x00005678                     |              |                                       |                       |
+| COPS Report-Type Object                  |              |                                       |                       |
+| Length<br>0x0008                         |              | C-Num<br>0x12                         | C-Type<br>0x01        |
+| Report Type (R-Type)<br>0x0001 (Success) |              | Reserved                              |                       |
+| COPS ClientSI Object Header              |              |                                       |                       |
+| Length<br>0x0024                         |              | C-Num<br>0x09                         | C-Type<br>0x01        |
+| Multimedia TransactionID Object          |              |                                       |                       |
+| Length<br>0x0008                         |              | S-Num<br>0x01                         | S-Type<br>0x01        |
+| TransactionID<br>0x0001                  |              | Gate Command<br>0x0005 (Gate-Set-Ack) |                       |
+| Multimedia AMID Object                   |              |                                       |                       |
+| Length<br>0x0008                         |              | S-Num<br>0x02                         | S-Type<br>0x01        |
+| AMID<br>0x00005678                       |              |                                       |                       |
+| Multimedia SubscriberID Object           |              |                                       |                       |
+| Length<br>0x0008                         |              | S-Num<br>0x03                         | S-Type<br>0x01        |
+| SubscriberID<br>0x01010101               |              |                                       |                       |
+| Multimedia GateID Object                 |              |                                       |                       |
+| Length<br>0x0008                         |              | S-Num<br>0x04                         | S-Type<br>0x01        |
+| GateID<br>0x12345678                     |              |                                       |                       |
+
+6c) The CMTS will also send a QoS\_Reserve Event message to signal to the RKS that the access network resources have been reserved.
+
+| 0                                                                                                                                                                                                   | 1                         | 2                                           | 3                    |
+|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------|---------------------------------------------|----------------------|
+| Accounting-Request Radius Header                                                                                                                                                                    |                           |                                             |                      |
+|                                                                                                                                                                                                     |                           |                                             |                      |
+|                                                                                                                                                                                                     |                           |                                             |                      |
+|                                                                                                                                                                                                     |                           |                                             |                      |
+| Radius Ven. Spec.<br>0x1A                                                                                                                                                                           | Length<br>0x54            | Vendor ID<br>0x0000                         |                      |
+| Vendor ID (cont.)<br>118B                                                                                                                                                                           |                           | Type (EM Header)<br>0x01                    | Length<br>0x4E       |
+| Version<br>0x0003                                                                                                                                                                                   |                           | BCID<br>0x3D48                              |                      |
+| BCID (cont.)<br>12082020202020313436302D303530303030303DB77                                                                                                                                         |                           |                                             |                      |
+|                                                                                                                                                                                                     |                           |                                             |                      |
+|                                                                                                                                                                                                     |                           |                                             |                      |
+|                                                                                                                                                                                                     |                           |                                             |                      |
+|                                                                                                                                                                                                     |                           | Event Message Type<br>0x0007 (QoS-Reserver) |                      |
+| Element Type<br>0x0002 (CMTS)                                                                                                                                                                       |                           | Element ID<br>0x2020202031323334            |                      |
+|                                                                                                                                                                                                     |                           | Time Zone<br>0x302D303530303030             |                      |
+|                                                                                                                                                                                                     |                           | Sequence Number<br>0x0000                   |                      |
+| Sequence Number (cont.)<br>0001                                                                                                                                                                     |                           | Event Time<br>0x3230                        |                      |
+| Event Time (cont.)<br>303331323036303030303030302E303030                                                                                                                                            |                           |                                             |                      |
+|                                                                                                                                                                                                     |                           |                                             |                      |
+|                                                                                                                                                                                                     |                           |                                             |                      |
+|                                                                                                                                                                                                     |                           |                                             |                      |
+| Status<br>0x00000000                                                                                                                                                                                |                           |                                             |                      |
+| Priority<br>0x80 (128)                                                                                                                                                                              | Attribute Count<br>0x0004 |                                             | Event Object<br>0x00 |
+| Radius Ven. Spec.<br>0x1A                                                                                                                                                                           | Length<br>0x5C            | Vendor ID<br>0x0000                         |                      |
+| Vendor ID (cont.)<br>118B                                                                                                                                                                           |                           | Type<br>0x20                                | Length<br>0x56       |
+| QoS_Descriptor<br>0x0003FFFD00000000000000000000000000000000000000000600004e200000032000000001000000e8<br>000000000000000000BE40000040000000000000005F20000017F000186A0000007D000FF0000<br>00000000 |                           |                                             |                      |
+|                                                                                                                                                                                                     |                           |                                             |                      |
+|                                                                                                                                                                                                     |                           |                                             |                      |
+|                                                                                                                                                                                                     |                           |                                             |                      |
+|                                                                                                                                                                                                     |                           |                                             |                      |
+
+**ITU-T Rec. J.179 (11/2005)** 103
+
+| 0                                   | 1              | 2                                                | 3              |
+|-------------------------------------|----------------|--------------------------------------------------|----------------|
+|                                     |                |                                                  |                |
+|                                     |                |                                                  |                |
+|                                     |                |                                                  |                |
+|                                     |                |                                                  |                |
+|                                     |                |                                                  |                |
+|                                     |                |                                                  |                |
+|                                     |                |                                                  |                |
+|                                     |                |                                                  |                |
+|                                     |                |                                                  |                |
+| Radius Ven. Spec.<br>0x1A           | Length<br>0x0C | Vendor ID<br>0x0000                              |                |
+| Vendor ID (cont.)<br>118B           |                | Type<br>0x1E                                     | Length<br>0x06 |
+| SF_ID<br>0x00000001                 |                |                                                  |                |
+| Radius Ven. Spec.<br>0x1A           | Length<br>0x0A | Vendor ID<br>0x0000                              |                |
+| Vendor ID (cont.)<br>118B           |                | Type<br>0x32                                     | Length<br>0x04 |
+| Flow Direction<br>0x0001 (Upstream) |                | Radius Ven. Spec.<br>0x1A                        | Length<br>0x0A |
+| Vendor ID<br>0x0000118B             |                |                                                  |                |
+| Type<br>0x37                        | Length<br>0x04 | Element_Requesting_QoS<br>0x0001 (Policy Server) |                |
+
+6d) Immediately after sending the QoS\_Reserve Event Message to the RKS, the CMTS will send the QoS\_Commit Event Message to the RKS. This is due to the fact that the access network resources are being reserved and committed in one step.
+
+| 0                                                            | 1              | 2                                         | 3              |
+|--------------------------------------------------------------|----------------|-------------------------------------------|----------------|
+| Accounting-Request Radius Header                             |                |                                           |                |
+|                                                              |                |                                           |                |
+|                                                              |                |                                           |                |
+|                                                              |                |                                           |                |
+| Radius Ven. Spec.<br>0x1A                                    | Length<br>0x54 | Vendor ID<br>0x0000                       |                |
+| Vendor ID (cont.)<br>118B                                    |                | Type (EM Header)<br>0x01                  | Length<br>0x4E |
+| Version<br>0x0003                                            |                | BCID<br>0x3E48                            |                |
+| BCID (cont.)<br>12082020202020313436302D3035303030300003DB77 |                |                                           |                |
+|                                                              |                |                                           |                |
+|                                                              |                |                                           |                |
+|                                                              |                |                                           |                |
+|                                                              |                | Event Message Type<br>0x0013 (QoS-Commit) |                |
+| Element Type<br>0x0002 (CMTS)                                |                | Element ID<br>0x2020202031323334          |                |
+
+104 ITU-T Rec. J.179 (11/2005)
+
+| 0                                                                                                                                                                                                       | 1                         | 2                               | 3                    |
+|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------|---------------------------------|----------------------|
+|                                                                                                                                                                                                         |                           | Time Zone<br>0x302d303530303030 |                      |
+|                                                                                                                                                                                                         |                           | Sequence Number<br>0x0000       |                      |
+| Sequence Number (cont.)<br>0002                                                                                                                                                                         |                           | Event Time<br>0x3230            |                      |
+| Event Time (cont.)<br>3033313230363030303030302E303030                                                                                                                                                  |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+| Status<br>0x00000000                                                                                                                                                                                    |                           |                                 |                      |
+| Priority<br>0x80 (128)                                                                                                                                                                                  | Attribute Count<br>0x0003 |                                 | Event Object<br>0x00 |
+| Radius Ven. Spec.<br>0x1A                                                                                                                                                                               | Length<br>0x5C            | Vendor ID<br>0x0000             |                      |
+| Vendor ID (cont.)<br>118B                                                                                                                                                                               |                           | Type<br>0x20                    | Length<br>0x56       |
+| QoS_Descriptor<br>0x0003FFFD0000000000000000000000000000000000000000600004e200000032000000001000000e8<br>0000000000000000000000BE400000040000000000000005F20000017F000186A0000007D000FF0000<br>00000000 |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+|                                                                                                                                                                                                         |                           |                                 |                      |
+| Radius Ven. Spec.<br>0x1A                                                                                                                                                                               | Length<br>0x0C            | Vendor ID<br>0x0000             |                      |
+| Vendor ID (cont.)<br>118B                                                                                                                                                                               |                           | Type<br>0x1E                    | Length<br>0x06       |
+| SF_ID<br>0x00000001                                                                                                                                                                                     |                           |                                 |                      |
+| Radius Ven. Spec.<br>0x1A                                                                                                                                                                               | Length<br>0x0A            | Vendor ID<br>0x0000             |                      |
+| Vendor ID (cont.)<br>118B                                                                                                                                                                               |                           | Type<br>0x32                    | Length<br>0x04       |
+| Flow Direction<br>0x0001 (Upstream)                                                                                                                                                                     |                           |                                 |                      |
+
+**ITU-T Rec. J.179 (11/2005)**     105
+
+7a) After receiving and recording the QoS\_Reserve Event Message, the RKS acknowledges the message.
+
+| 0                                 | 1 | 2 | 3 |
+|-----------------------------------|---|---|---|
+| Accounting-Response Radius Header |   |   |   |
+| -----                             |   |   |   |
+| -----                             |   |   |   |
+| -----                             |   |   |   |
+
+7b) After receiving and recording the QoS\_Commit Event Message, the RKS acknowledges the message.
+
+| 0                                 | 1 | 2 | 3 |
+|-----------------------------------|---|---|---|
+| Accounting-Response Radius Header |   |   |   |
+| -----                             |   |   |   |
+| -----                             |   |   |   |
+| -----                             |   |   |   |
+
+7c) As a result of receiving a Gate-Set-Ack from the CMDS, the Policy Server will send a Gate-Set-Ack to the Application Manager to complete the transaction.
+
+| 0                                        | 1            | 2                      | 3                     |
+|------------------------------------------|--------------|------------------------|-----------------------|
+| COPS Header                              |              |                        |                       |
+| Version<br>0x1                           | Flags<br>0x1 | Op-Code<br>0x03        | Client-Type<br>0x800A |
+| Message Length<br>0x0000003C             |              |                        |                       |
+| COPS Handle Object                       |              |                        |                       |
+| Length<br>0x0008                         |              | C-Num<br>0x01          | C-Type<br>0x01        |
+| Handle<br>0x00001234                     |              |                        |                       |
+| COPS Report-Type Object                  |              |                        |                       |
+| Length<br>0x0008                         |              | C-Num<br>0x12          | C-Type<br>0x01        |
+| Report Type (R-Type)<br>0x0001 (Success) |              | Reserved               |                       |
+| COPS ClientSI Object Header              |              |                        |                       |
+| Length<br>0x0024                         |              | C-Num<br>0x09          | C-Type<br>0x01        |
+| Multimedia TransactionID Object          |              |                        |                       |
+| Length<br>0x0008                         |              | S-Num<br>0x01          | S-Type<br>0x01        |
+| TransactionID<br>0x9999                  |              | Gate Command<br>0x0005 |                       |
+| Multimedia AMID Object                   |              |                        |                       |
+| Length<br>0x0008                         |              | S-Num<br>0x02          | S-Type<br>0x01        |
+| AMID<br>0x00005678                       |              |                        |                       |
+| Multimedia SubscriberID Object           |              |                        |                       |
+| Length<br>0x0008                         |              | S-Num<br>0x03          | S-Type<br>0x01        |
+| SubscriberID<br>0x01010101               |              |                        |                       |
+
+| 0                        | 1             | 2 | 3              |
+|--------------------------|---------------|---|----------------|
+| Multimedia GateID Object |               |   |                |
+| Length<br>0x0008         | S-Num<br>0x04 |   | S-Type<br>0x01 |
+| GateID<br>0x12345678     |               |   |                |
+
+7d) The Policy Server will also send a Policy\_Request Event Message to the RKS to track the Policy Request and associated outcome.
+
+| 0                                                            | 1                         | 2                                             | 3                    |  |  |
+|--------------------------------------------------------------|---------------------------|-----------------------------------------------|----------------------|--|--|
+| Accounting-Request Radius Header                             |                           |                                               |                      |  |  |
+| -----                                                        |                           |                                               |                      |  |  |
+| -----                                                        |                           |                                               |                      |  |  |
+| -----                                                        |                           |                                               |                      |  |  |
+| Radius Ven. Spec.<br>0x1A                                    | Length<br>0x54            | Vendor ID<br>0x0000                           |                      |  |  |
+| Vendor ID (cont.)<br>118B                                    |                           | Type (EM Header)<br>0x01                      | Length<br>0x4E       |  |  |
+| Version<br>0x0001                                            |                           | BCID<br>0x3E48                                |                      |  |  |
+| BCID (cont.)<br>12082020202020313436302D3035303030300003DB77 |                           |                                               |                      |  |  |
+| -----                                                        |                           |                                               |                      |  |  |
+| -----                                                        |                           |                                               |                      |  |  |
+| -----                                                        |                           |                                               |                      |  |  |
+| -----                                                        |                           |                                               |                      |  |  |
+|                                                              |                           | Event Message Type<br>0x0015 (Policy_Request) |                      |  |  |
+| Element Type<br>0x0004 (Policy Server)                       |                           | Element ID<br>0x2020202035363738              |                      |  |  |
+| -----                                                        |                           |                                               |                      |  |  |
+|                                                              |                           | Time Zone<br>0x302E303530303030               |                      |  |  |
+| -----                                                        |                           |                                               |                      |  |  |
+|                                                              |                           | Sequence Number<br>0x0000                     |                      |  |  |
+| Sequence Number (cont.)<br>0001                              |                           | Event Time<br>0x3230                          |                      |  |  |
+| -----                                                        |                           |                                               |                      |  |  |
+| Event Time (cont.)<br>30333132303630303030302E323130         |                           |                                               |                      |  |  |
+| -----                                                        |                           |                                               |                      |  |  |
+| -----                                                        |                           |                                               |                      |  |  |
+| -----                                                        |                           |                                               |                      |  |  |
+| Status<br>0x00000000                                         |                           |                                               |                      |  |  |
+| Priority<br>0x80 (128)                                       | Attribute Count<br>0x0004 |                                               | Event Object<br>0x00 |  |  |
+| Radius Ven. Spec.<br>0x1A                                    | Length<br>0x0C            | Vendor ID<br>0x0000                           |                      |  |  |
+| Vendor ID (cont.)<br>118B                                    |                           | Type<br>0x3D                                  | Length<br>0x06       |  |  |
+| Application_Manager_ID<br>0x00005678                         |                           |                                               |                      |  |  |
+| Radius Ven. Spec.<br>0x1A                                    | Length<br>0x0C            | Vendor ID<br>0x0000                           |                      |  |  |
+
+| 0                                                                                                 | 1              | 2                         | 3              |
+|---------------------------------------------------------------------------------------------------|----------------|---------------------------|----------------|
+| Vendor ID (cont.)<br>118B                                                                         |                | Type<br>0x34              | Length<br>0x06 |
+| Subscriber_ID<br>0x01010101                                                                       |                |                           |                |
+| Radius Ven. Spec.<br>0x1A                                                                         | Length<br>0x0A | Vendor ID<br>0x0000       |                |
+| Vendor ID (cont.)<br>118B                                                                         |                | Type<br>0x3C              | Length<br>0x04 |
+| Policy_Decision_Status<br>0x0001 (Policy Approved)                                                |                | Radius Ven. Spec.<br>0x1A | Length<br>0x1C |
+| Vendor ID<br>0x0000118B                                                                           |                |                           |                |
+| Type<br>0x31                                                                                      | Length<br>0x16 | FEID<br>0x0000            |                |
+| -----<br>FEID (cont.)<br>000000000000005061636B65744361626C65<br>-----<br>-----<br>-----<br>----- |                |                           |                |
+
+- 8) After receiving and recording the Policy\_Request Event Message, the RKS acknowledges the message.
+
+| 0                                 | 1 | 2 | 3 |
+|-----------------------------------|---|---|---|
+| Accounting-Response Radius Header |   |   |   |
+| -----                             |   |   |   |
+| -----                             |   |   |   |
+| -----                             |   |   |   |
+
+- 9) The Application Manager will reply to the client to inform the client that it can now play the game. This signalling is out of the scope of this Recommendation.
+- 10) When the client has finished with the application, it will notify the Application Manager. This signalling is out of the scope of this Recommendation.
+- 11) The Application Manager will terminate the session by sending a Gate-Delete to the Policy Server.
+
+| 0                                                       | 1            | 2                               | 3                     |
+|---------------------------------------------------------|--------------|---------------------------------|-----------------------|
+| COPS Header                                             |              |                                 |                       |
+| Version<br>0x1                                          | Flags<br>0x0 | Op-Code<br>0x02                 | Client-Type<br>0x800A |
+| Message Length<br>0x00000044                            |              |                                 |                       |
+| COPS Handle Object                                      |              |                                 |                       |
+| Length<br>0x0008                                        |              | C-Num<br>0x01                   | C-Type<br>0x01        |
+| Handle<br>0x00001234                                    |              |                                 |                       |
+| COPS Context Object                                     |              |                                 |                       |
+| Length<br>0x0008                                        |              | C-Num<br>0x02                   | C-Type<br>0x01        |
+| Request Type (R-Type)<br>0x0008 (Configuration Request) |              | Message Type (M-Type)<br>0x0000 |                       |
+
+| 0                                                         | 1                                    | 2             | 3              |
+|-----------------------------------------------------------|--------------------------------------|---------------|----------------|
+| COPS Decision Flags Object                                |                                      |               |                |
+| Length<br>0x0008                                          |                                      | C-Num<br>0x06 | C-Type<br>0x01 |
+| Command Code<br>0x0001 (Install Configuration)            | Flags<br>0x0000                      |               |                |
+| COPS Decision Client Specific Decision Data Object Header |                                      |               |                |
+| Length<br>0x0014                                          |                                      | C-Num<br>0x06 | C-Type<br>0x04 |
+| Multimedia TransactionID Object                           |                                      |               |                |
+| Length<br>0x0008                                          |                                      | S-Num<br>0x01 | S-Type<br>0x01 |
+| TransactionID<br>0x9998                                   | Gate Command<br>0x000A (Gate-Delete) |               |                |
+| Multimedia AMID Object                                    |                                      |               |                |
+| Length<br>0x0008                                          |                                      | S-Num<br>0x02 | S-Type<br>0x01 |
+| AMID<br>0x00005678                                        |                                      |               |                |
+| Multimedia SubscriberID Object                            |                                      |               |                |
+| Length<br>0x0008                                          |                                      | S-Num<br>0x03 | S-Type<br>0x01 |
+| SubscriberID<br>0x01010101                                |                                      |               |                |
+| Multimedia GateID Object                                  |                                      |               |                |
+| Length<br>0x0008                                          |                                      | S-Num<br>0x04 | S-Type<br>0x01 |
+| GateID<br>0x12345678                                      |                                      |               |                |
+
+12) The Policy Server will instruct the CMTS to tear down the session by sending a Gate-Delete.
+
+| 0                                                         | 1                               | 2               | 3                     |
+|-----------------------------------------------------------|---------------------------------|-----------------|-----------------------|
+| COPS Header                                               |                                 |                 |                       |
+| Version<br>0x1                                            | Flags<br>0x0                    | Op-Code<br>0x02 | Client-Type<br>0x800A |
+| Message Length<br>0x00000044                              |                                 |                 |                       |
+| COPS Handle Object                                        |                                 |                 |                       |
+| Length<br>0x0008                                          |                                 | C-Num<br>0x01   | C-Type<br>0x01        |
+| Handle<br>0x00005678                                      |                                 |                 |                       |
+| COPS Context Object                                       |                                 |                 |                       |
+| Length<br>0x0008                                          |                                 | C-Num<br>0x02   | C-Type<br>0x01        |
+| Request Type (R-Type)<br>0x0008 (Configuration Request)   | Message Type (M-Type)<br>0x0000 |                 |                       |
+| COPS Decision Flags Object                                |                                 |                 |                       |
+| Length<br>0x0008                                          |                                 | C-Num<br>0x06   | C-Type<br>0x01        |
+| Command Code<br>0x0001 (Install Configuration)            | Flags<br>0x0000                 |                 |                       |
+| COPS Decision Client Specific Decision Data Object Header |                                 |                 |                       |
+| Length<br>0x0014                                          |                                 | C-Num<br>0x09   | C-Type<br>0x01        |
+
+| 0                               | 1 | 2                                    | 3              |
+|---------------------------------|---|--------------------------------------|----------------|
+| Multimedia TransactionID Object |   |                                      |                |
+| Length<br>0x0008                |   | S-Num<br>0x01                        | S-Type<br>0x01 |
+| TransactionID<br>0x0002         |   | Gate Command<br>0x000A (Gate-Delete) |                |
+| Multimedia AMID Object          |   |                                      |                |
+| Length<br>0x0008                |   | S-Num<br>0x02                        | S-Type<br>0x01 |
+| AMID<br>0x00005678              |   |                                      |                |
+| Multimedia SubscriberID Object  |   |                                      |                |
+| Length<br>0x0008                |   | S-Num<br>0x03                        | S-Type<br>0x01 |
+| SubscriberID<br>0x01010101      |   |                                      |                |
+| Multimedia GateID Object        |   |                                      |                |
+| Length<br>0x0008                |   | S-Num<br>0x04                        | S-Type<br>0x01 |
+| GateID<br>0x12345678            |   |                                      |                |
+
+13) The CMTS will tear down the access network resources by sending a DSD-REQ to the CM.
+
+| 0                       | 1 | 2        | 3 |
+|-------------------------|---|----------|---|
+| MAC Management Header   |   |          |   |
+| -----                   |   |          |   |
+| -----                   |   |          |   |
+| -----                   |   |          |   |
+| TransactionID<br>0x0008 |   | Reserved |   |
+| SFID<br>0x00000001      |   |          |   |
+
+14) The CM will acknowledge the session deletion with a DSD-RSP.
+
+| 0                       | 1 | 2                     | 3        |
+|-------------------------|---|-----------------------|----------|
+| MAC Management Header   |   |                       |          |
+| -----                   |   |                       |          |
+| -----                   |   |                       |          |
+| -----                   |   |                       |          |
+| TransactionID<br>0x0008 |   | Confirm. Code<br>0x00 | Reserved |
+
+15a) The CMTS will complete the Gate-Control transaction with a Gate-Delete-Ack.
+
+| 0                            | 1            | 2               | 3                     |
+|------------------------------|--------------|-----------------|-----------------------|
+| COPS Header                  |              |                 |                       |
+| Version<br>0x1               | Flags<br>0x1 | Op-Code<br>0x03 | Client-Type<br>0x800A |
+| Message Length<br>0x00000034 |              |                 |                       |
+
+| 0                               | 1 | 2                        | 3      |
+|---------------------------------|---|--------------------------|--------|
+| COPS Handle Object              |   |                          |        |
+| Length                          |   | C-Num                    | C-Type |
+| 0x0008                          |   | 0x01                     | 0x01   |
+| Handle                          |   |                          |        |
+| 0x00005678                      |   |                          |        |
+| COPS Report Type Object         |   |                          |        |
+| Length                          |   | C-Num                    | C-Type |
+| 0x0008                          |   | 0x12                     | 0x01   |
+| Report Type (R-Type)            |   | Reserved                 |        |
+| 0x0001                          |   |                          |        |
+| COPS ClientSI Object Header     |   |                          |        |
+| Length                          |   | C-Num                    | C-Type |
+| 0x001C                          |   | 0x09                     | 0x01   |
+| Multimedia TransactionID Object |   |                          |        |
+| Length                          |   | S-Num                    | S-Type |
+| 0x0008                          |   | 0x01                     | 0x01   |
+| TransactionID                   |   | Gate Command             |        |
+| 0x0002                          |   | 0x000B (Gate-Delete-Ack) |        |
+| Multimedia AMID Object          |   |                          |        |
+| Length                          |   | S-Num                    | S-Type |
+| 0x0008                          |   | 0x02                     | 0x01   |
+| AMID                            |   |                          |        |
+| 0x00005678                      |   |                          |        |
+| Multimedia GateID Object        |   |                          |        |
+| Length                          |   | S-Num                    | S-Type |
+| 0x0008                          |   | 0x04                     | 0x01   |
+| GateID                          |   |                          |        |
+| 0x12345678                      |   |                          |        |
+
+15b) Also upon the receipt of the DSD-RSP, the CMTS will inform the RKS that the network access resources have been freed by sending a QoS\_Release.
+
+| 0                                              | 1      | 2                    | 3      |
+|------------------------------------------------|--------|----------------------|--------|
+| Accounting-Request Radius Header               |        |                      |        |
+|                                                |        |                      |        |
+|                                                |        |                      |        |
+|                                                |        |                      |        |
+| Radius Ven. Spec.                              | Length | Vendor ID            |        |
+| 0x1A                                           | 0x54   | 0x0000               |        |
+| Vendor ID (cont.)                              |        | Type (EM Header)     | Length |
+| 118B                                           |        | 0x01                 | 0x4E   |
+| Version                                        |        | BCID                 |        |
+| 0x0001                                         |        | 0x3E48               |        |
+| BCID (cont.)                                   |        |                      |        |
+| 1208202020202020313436302D3035303030300003DB77 |        |                      |        |
+|                                                |        |                      |        |
+|                                                |        |                      |        |
+|                                                |        |                      |        |
+|                                                |        | Event Message Type   |        |
+|                                                |        | 0x0008 (QoS_Release) |        |
+
+ITU-T Rec. J.179 (11/2005) 111
+
+| 0                                                    | 1                                | 2                                                | 3 |  |  |  |
+|------------------------------------------------------|----------------------------------|--------------------------------------------------|---|--|--|--|
+| Element Type<br>0x0002 (CMTS)                        | Element ID<br>0x2020202031323334 |                                                  |   |  |  |  |
+|                                                      | Time Zone<br>0x302D303530303030  |                                                  |   |  |  |  |
+|                                                      | Sequence Number<br>0x0000        |                                                  |   |  |  |  |
+| Sequence Number (cont.)<br>0003                      | Event Time<br>0x3230             |                                                  |   |  |  |  |
+| Event Time (cont.)<br>30323132303630303030302E333030 |                                  |                                                  |   |  |  |  |
+| Status<br>0x00000000                                 |                                  |                                                  |   |  |  |  |
+| Priority<br>0x80 (128)                               | Attribute Count<br>0x0005        | Event Object<br>0x00                             |   |  |  |  |
+| Radius Ven. Spec.<br>0x1A                            | Length<br>0x0C                   | Vendor ID<br>0x0000                              |   |  |  |  |
+| Vendor ID (cont.)<br>118B                            | Type<br>0x1E                     | Length<br>0x06                                   |   |  |  |  |
+| SF_ID<br>0x00000001                                  |                                  |                                                  |   |  |  |  |
+| Radius Ven. Spec.<br>0x1A                            | Length<br>0x0A                   | Vendor ID<br>0x0000                              |   |  |  |  |
+| Vendor ID (cont.)<br>118B                            | Type<br>0x32                     | Length<br>0x04                                   |   |  |  |  |
+| Flow_Direction<br>0x0001 (Upstream)                  | Radius Ven. Spec.<br>0x1A        | Length<br>0x0A                                   |   |  |  |  |
+| Vendor ID<br>0x0000118B                              |                                  |                                                  |   |  |  |  |
+| Type<br>0x38                                         | Length<br>0x04                   | QoS_Release_Reason<br>0x0001 (Gate Closed by PS) |   |  |  |  |
+| Radius Ven. Spec.<br>0x1A                            | Length<br>0x0C                   | Vendor ID<br>0x0000                              |   |  |  |  |
+| Vendor ID (cont.)<br>118B                            | Type<br>0x36                     | Length<br>0x06                                   |   |  |  |  |
+| QoS_Usage_Info<br>0x77777777 (bytes)                 |                                  |                                                  |   |  |  |  |
+| Radius Ven. Spec.<br>0x1A                            | Length<br>0x0C                   | Vendor ID<br>0x0000                              |   |  |  |  |
+| Vendor ID (cont.)<br>118B                            | Type<br>0x3F                     | Length<br>0x06                                   |   |  |  |  |
+| QoS_Time_Info<br>0x77777777 (seconds)                |                                  |                                                  |   |  |  |  |
+
+16a) After receiving and recording the QoS\_Release Event Message, the RKS acknowledges the message.
+
+| 0                                 | 1 | 2 | 3 |
+|-----------------------------------|---|---|---|
+| Accounting-Response Radius Header |   |   |   |
+
+16b) After receiving the Gate-Delete-Ack from the CMTS, the Policy Server will send a Gate-Delete-Ack to complete the Gate-Control transaction.
+
+| 0                                        | 1            | 2                                        | 3                     |
+|------------------------------------------|--------------|------------------------------------------|-----------------------|
+| COPS Header                              |              |                                          |                       |
+| Version<br>0x1                           | Flags<br>0x1 | Op-Code<br>0x03                          | Client-Type<br>0x800A |
+| Message Length<br>0x00000034             |              |                                          |                       |
+| COPS Handle Object                       |              |                                          |                       |
+| Length<br>0x0008                         |              | C-Num<br>0x01                            | C-Type<br>0x01        |
+| Handle<br>0x00001234                     |              |                                          |                       |
+| COPS Report-Type Object                  |              |                                          |                       |
+| Length<br>0x0008                         |              | C-Num<br>0x12                            | C-Type<br>0x01        |
+| Report Type (R-Type)<br>0x0001 (Success) |              | Reserved                                 |                       |
+| COPS ClientSI Object Header              |              |                                          |                       |
+| Length<br>0x001C                         |              | C-Num<br>0x09                            | C-Type<br>0x01        |
+| Multimedia TransactionID Object          |              |                                          |                       |
+| Length<br>0x0008                         |              | S-Num<br>0x01                            | S-Type<br>0x01        |
+| TransactionID<br>0x9998                  |              | Gate Command<br>0x000B (Gate-Delete-Ack) |                       |
+| Multimedia AMID Object                   |              |                                          |                       |
+| Length<br>0x0008                         |              | S-Num<br>0x02                            | S-Type<br>0x01        |
+| AMID<br>0x00005678                       |              |                                          |                       |
+| Multimedia GateID Object                 |              |                                          |                       |
+| Length<br>0x0008                         |              | S-Num<br>0x04                            | S-Type<br>0x01        |
+| GateID<br>0x12345678                     |              |                                          |                       |
+
+16c) The Policy Server sends a Policy\_Delete Event Message to the RKS to complete the entire process.
+
+| 0                                | 1              | 2                        | 3              |
+|----------------------------------|----------------|--------------------------|----------------|
+| Accounting-Request Radius Header |                |                          |                |
+| -----                            |                |                          |                |
+| -----                            |                |                          |                |
+| -----                            |                |                          |                |
+| Radius Ven. Spec.<br>0x1A        | Length<br>0x54 | Vendor ID<br>0x0000      |                |
+| Vendor ID (cont.)<br>118B        |                | Type (EM Header)<br>0x01 | Length<br>0x4E |
+| Version<br>0x0001                |                | BCID<br>0x3E48           |                |
+| -----                            |                |                          |                |
+
+| 0                                          | 1               | 2                      | 3            |  |  |
+|--------------------------------------------|-----------------|------------------------|--------------|--|--|
+| BCID (cont.)                               |                 |                        |              |  |  |
+| 12082020202020313436302D30353030300003DB77 |                 |                        |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+|                                            |                 | Event Message Type     |              |  |  |
+|                                            |                 | 0x0016 (Policy_Delete) |              |  |  |
+| Element Type                               |                 | Element ID             |              |  |  |
+| 0x0004 (Policy Server)                     |                 | 0x2020202035363738     |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+|                                            |                 | Time Zone              |              |  |  |
+|                                            |                 | 0x302D303530303030     |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+|                                            |                 | Sequence Number        |              |  |  |
+|                                            |                 | 0x0000                 |              |  |  |
+| Sequence Number (cont.)                    |                 | Event Time             |              |  |  |
+| 0002                                       |                 | 0x3230                 |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+| Event Time (cont.)                         |                 |                        |              |  |  |
+| 30323132303630303030302E343030             |                 |                        |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+| Status                                     |                 |                        |              |  |  |
+| 0x00000000                                 |                 |                        |              |  |  |
+| Priority                                   | Attribute Count |                        | Event Object |  |  |
+| 0x80                                       | 0x0004          |                        | 0x00         |  |  |
+| Radius Ven. Spec.                          | Length          | Vendor ID              |              |  |  |
+| 0x1A                                       | 0x0C            | 0x0000                 |              |  |  |
+| Vendor ID (cont.)                          |                 | Type                   | Length       |  |  |
+| 118B                                       |                 | 0x3D                   | 0x06         |  |  |
+| Application_Manager_ID                     |                 |                        |              |  |  |
+| 0x00005678                                 |                 |                        |              |  |  |
+| Radius Ven. Spec.                          | Length          | Vendor ID              |              |  |  |
+| 0x1A                                       | 0x0C            | 0x0000                 |              |  |  |
+| Vendor ID (cont.)                          |                 | Type                   | Length       |  |  |
+| 118B                                       |                 | 0x34                   | 0x06         |  |  |
+| Subscriber_ID                              |                 |                        |              |  |  |
+| 0x01010101                                 |                 |                        |              |  |  |
+| Radius Ven. Spec.                          | Length          | Vendor ID              |              |  |  |
+| 0x1A                                       | 0x0A            | 0x0000                 |              |  |  |
+| Vendor ID (cont.)                          |                 | Type                   | Length       |  |  |
+| 118B                                       |                 | 0x3A                   | 0x04         |  |  |
+| Policy_Deleted_Reason                      |                 | Radius Ven. Spec.      | Length       |  |  |
+| 0x0001 (Application Manager Request)       |                 | 0x1A                   | 0x1C         |  |  |
+| Vendor ID                                  |                 |                        |              |  |  |
+| 0x0000118B                                 |                 |                        |              |  |  |
+| Type                                       | Length          | FEID                   |              |  |  |
+| 0x31                                       | 0x16            | 0x0000                 |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+| FEID (cont.)                               |                 |                        |              |  |  |
+| 000000000000005061636B65744361626C65       |                 |                        |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+| -----                                      |                 |                        |              |  |  |
+
+- 17) After receiving and recording the Policy\_Delete Event Message, the RKS acknowledges the message.
+
+| 0                                 | 1 | 2 | 3 |
+|-----------------------------------|---|---|---|
+| Accounting-Response Radius Header |   |   |   |
+| -----                             |   |   |   |
+| -----                             |   |   |   |
+
+# 11 Issues for future study
+
+The following issues have been identified as topics for future study.
+
+- Error-handling requirements (i.e., mandate specific error codes for specific conditions).
+- Gate Control message routing within the Multimedia framework.
+- State synchronization requirements (i.e., granularity, scope, frequency, etc.) and protocol mechanism.
+- Protocol support for failover and redundancy strategies. Also, how gates should be handled in the event of a failed COPS connection.
+- Policy Server rule format and provisioning mechanism: CMS provisioning with Multimedia-specific XML DTD.
+- Support for Payload Header Suppression (PHS).
+- Gate Control message delivery for failed connections (currently these messages are suppressed).
+
+# Appendix I
+
+## Background information
+
+## I.1 Introduction
+
+This appendix describes an architecture which provides an IP-based platform to support a variety of multimedia applications and services requiring QoS treatment over CableModem access networks. This architecture defines functional components and protocol interfaces that will enable each cable operator to deliver the QoS-enhanced multimedia services that meet their unique business requirements.
+
+Because the architecture is agnostic of the application-level details of particular multimedia offerings, specific provisioning, signalling and operations support system (OSS) functions required to provide a particular service are out of the scope of this Recommendation. Rather, the focus of IPCablecom Multimedia centres on the delivery of reliable QoS over the access network, specifically addressing the technical issues of policy authorization, QoS signalling, resource accounting, and security.
+
+### I.1.1 IPCablecom overview
+
+The IPCablecom project is aimed at defining interface specifications used by the vendor community to develop interoperable equipment capable of providing IP-based voice, video and other high-speed multimedia services over hybrid fibre coax (HFC) cable systems which conform to the CableModem broadband access network Recommendations.
+
+Voice over IP (VoIP) was the first such service identified for delivery over the IPCablecom platform. The current set of IPCablecom Recommendations, known collectively as IPCablecom-T, define an IPCablecom architecture optimized for the delivery of residential VoIP services. See ITU-T Rec. J.160.
+
+### I.1.2 IPCablecom multimedia motivation
+
+Like VoIP, most popular multimedia applications (e.g., online gaming, streaming media, real-time video communication) are sensitive to transmission delay within the network. Further, as new applications emerge that are designed to take advantage of broadband networks, they, too, will present unique bandwidth and latency requirements.
+
+Currently, broadband customers receive multimedia services via best-effort data delivery. This results in an inconsistent online experience that varies in quality based on bandwidth availability and congestion in the network. A network that is able to reserve resources and deliver bandwidth on demand, as service requirements dictate, will be positioned to provide a wide variety of new services for their customers.
+
+In order to address these needs for VoIP services, IPCablecom currently defines dynamic Quality of Service (DQoS) signalling mechanisms that allow voice applications to request and obtain bandwidth from the CableModem data link layer. The current DQoS framework also supports secure session establishment through endpoint authentication and authorization and a QoS-based usage tracking model. Based on these core capabilities, the IPCablecom architecture is well positioned to support existing and future QoS-enhanced applications and services beyond telephony.
+
+The primary objective of IPCablecom Multimedia is to define the core architectural framework required to support QoS-based multimedia applications. At the heart of this framework are the Quality of Service mechanisms defined in the CableModem and IPCablecom DQoS Specifications. Successful completion of this initiative will provide a strong technical foundation to support specific multimedia service offerings going forward.
+
+## **I.2 IPCablecom multimedia objectives and scope**
+
+The main objective of IPCablecom Multimedia is to develop a general-purpose architecture that:
+
+- Supports a wide range of QoS-enabled services, beyond-voice;
+- Is based on existing mechanisms defined in IPCablecom-T and CableModem Recommendations;
+- Requires a minimal set of extensions beyond IPCablecom-T;
+- Reduces development complexity by eliminating telephony-specific requirements where not applicable (e.g., PSTN interconnect, electronic surveillance, telephony billing models, etc.);
+- Co-exists with the IPCablecom-T architecture in such a way that:
+  - IPCablecom Multimedia requirements are sufficient to support a QoS-based multimedia service delivery platform;
+  - IPCablecom Multimedia requirements may be added to relevant existing IPCablecom-T functional components;
+  - IPCablecom-T requirements may be added to relevant IPCablecom Multimedia functional components;
+- Supports IPCablecom-T MTAs as "Client Type 2" devices (defined within) in the IPCablecom Multimedia architecture;
+- Interoperates with the IPCable2Home (ITU-T Rec. J.191) and CableModem (ITU-T Recs J.112 and J.122) architectures.
+
+This clause describes the requirements which have been identified in order to satisfy the above objectives and outlines the scope of the work that will be addressed by the architecture.
+
+### **I.2.1 Requirements**
+
+This architecture outlines the interaction of a variety of network elements, including Client Devices, Application Managers, Policy Servers, CMTSs and Cable Modems. These network elements are formally defined in the Multimedia Framework clause of this appendix. However, specific assumptions regarding management authority and trust relationships have made about some of these network elements, and these assumptions are captured below as IPCablecom Multimedia requirements. High-level requirements addressing QoS signalling, resource management, event messaging and security are also included in this clause.
+
+IP Cablecom Multimedia is application signalling protocol-agnostic concerning interaction between the Client Device and Application Manager. It is understood that the Client Device and Application Manager may support a variety of application and signalling protocols (e.g., HTTP, SIP, H.323, DCS, NCS, etc.).
+
+Client Devices in the IPCablecom Multimedia architecture:
+
+- 1) reside directly on the operator access network, or within the home;
+- 2) may be standalone devices or may contain an embedded CableModem; and
+- 3) are considered untrusted network elements and, as such, some form of authentication of the user, application, or application messaging may be required by the operator network.
+
+Application Managers in the IPCablecom Multimedia architecture:
+
+- 1) reside on the operator-managed network;
+- 2) are managed by the operator; and
+- 3) are responsible for ensuring that clients requesting service from the operator network are authorized to receive that service.
+
+Policy Servers in the IPCablecom Multimedia architecture:
+
+- 1) reside in the operator-managed network
+- 2) are managed by the operator; and
+- 3) are responsible for making QoS-related policy decisions based on operator-defined policy rules.
+
+CMTSs in the IPCablecom Multimedia architecture are responsible for enforcing QoS-related policy decisions.
+
+#### **QoS signalling and resource management requirements:**
+
+- Dynamic resource request mechanisms must be defined, including:
+  - Access to all CableModem QoS scheduling models;
+  - Time-restricted resource requests;
+  - Volume-restricted resource requests.
+- Single-phase and two-phase resource reservation models must be supported.
+- Unidirectional reservations must be supported; support for bidirectional reservations should be allowed.
+- Application Managers may initiate QoS reservation requests on behalf of Client Devices.
+- The architecture must provide a means to detect client and/or server failures and reclaim associated resources.
+
+#### **Event message information collection requirements:**
+
+- A comprehensive set of event messages must be defined to track per-flow resource usage, including:
+  - Policy event denoting a request for access-network resources, subject to operator-defined policy rules;
+  - Policy event denoting the release of access-network resources;
+  - QoS events denoting reservation, commitment, and release of QoS resources;
+  - Additional event(s) supporting per-flow resource usage based on volume (metered packet counts).
+- The following information should be contained in the messages:
+  - Source of request (e.g., subscriber or service provider);
+  - Characteristics of the requested resources;
+  - Policy authorization decision.
+
+#### **Security requirements:**
+
+- Security is required and must be defined for relevant interfaces.
+- Clients that initiate QoS signalling may require some form of authentication of the user or the application.
+
+### **I.2.2 Scope**
+
+The following items outline the current, initial phase scope of the IPCablecom Multimedia initiative:
+
+- The architecture will address network elements that reside:
+  - 1) on the access network; or
+  - 2) within a single operator's managed IP network.
+
+- The architecture will define the protocols and interfaces necessary to support policy authorization, QoS admission control, resource accounting, and security mechanisms.
+- The architecture will not address application-specific issues (e.g., service provisioning, signalling, billing, etc).
+- The architecture will not address provisioning and OSS requirements for IPCablecom Multimedia network elements.
+- The architecture will focus on QoS management between the CMTS and CM.
+- The architecture will not preclude the delivery of multicast services, even though it will not explicitly address multicast considerations.
+- The architecture will not address Network Address Translation (NAT) traversal and interoperability requirements at the present time.
+- The architecture will not define end-to-end QoS requirements in the present phase.
+- The architecture will provide support for "Client Type 1" and "Scenario 1" (as defined within) in the present phase. For completeness and in anticipation of future elaboration, this appendix describes all three client types and all three service scenarios.
+- The architecture will not provide dynamic topology discovery (i.e., relationships among Application Managers, Policy Servers, CMTSs, RKSs, etc.) in the present phase.
+- The architecture will not address Client authentication by the Application Manager.
+- The architecture will not address specific mechanisms by which the Policy Server obtains and manages policy rules.
+- The architecture will not support the collection of application or service-specific events for incorporation into the resource usage audit trail.
+
+## I.3 IPCablecom multimedia framework
+
+To facilitate the delivery of quality broadband multimedia applications requiring QoS guarantees, the multimedia framework offers general-purpose QoS functionality based on mechanisms defined in the core IPCablecom-T specifications. In support of this objective, several key network elements have been identified and profiled. Figure I.1 presents the IPCablecom Multimedia components which reside within the operator's managed IP network.
+
+![Diagram of Operator multimedia network elements showing various servers connected to a central cloud representing the operator-managed IP environment, which is also connected to a CMTS.](3ec35c497a0765a1a885c85f214b1bef_img.jpg)
+
+```
+
+graph LR
+    subgraph Servers
+        AM[Application Manager (AM)]
+        MS[Media Server (Optional)]
+        PS[Policy Server (PS)]
+        RKS[Record Keeping Server (RKS)]
+        SS[Security Server]
+        OSS[Operations Support Systems (OSS)]
+    end
+    AM --- OME((Operator-managed IP environment))
+    MS --- OME
+    PS --- OME
+    RKS --- OME
+    SS --- OME
+    OSS --- OME
+    OME --- CMTS[CMTS]
+    J179_FI.1[J.179_FI.1]
+  
+```
+
+The diagram illustrates the architecture of operator multimedia network elements. On the left, six rectangular boxes represent different network elements: Application Manager (AM), Media Server (Optional), Policy Server (PS), Record Keeping Server (RKS), Security Server, and Operations Support Systems (OSS). Each of these boxes has a line connecting it to a central cloud-shaped element labeled "Operator-managed IP environment". To the right of the cloud, a line connects it to a rectangular box labeled "CMTS". Below the CMTS box, the text "J.179\_FI.1" is present.
+
+Diagram of Operator multimedia network elements showing various servers connected to a central cloud representing the operator-managed IP environment, which is also connected to a CMTS.
+
+**Figure I.1/J.179 – Operator multimedia network elements**
+
+In addition to a CMTS facilitating parameter-based QoS capabilities, the operator multimedia network architecture consists of a server farm which may be further divided into the following areas:
+
+- An Application Manager and (optional) Media Server hosting a QoS-enabled application;
+- A policy administration framework providing QoS authorization and admission control in support of per-flow network resource management;
+- An event messaging subsystem used to monitor and record resource usage information.
+
+Operations support systems to perform provisioning, network management, and monitoring functions may also be included in the operator multimedia network configuration, though these elements fall outside the scope of the current architecture.
+
+### 1.3.1 IPCablecom multimedia architecture reference model
+
+In addition to the elements residing within the operator head-end network, a number of client devices located on the customer premises have also been defined in order to complete the model. Figure I.2 shows the IPCablecom Multimedia architectural framework and identifies key interfaces between the components. These interfaces have been tagged with identifiers which will be referenced in the discussion that follows.
+
+![Diagram of the IPCablecom multimedia architectural framework showing the flow of data and control signals between a Client, Cable modem, CMTS, Policy server, Record keeping server, Application manager, and Operator-managed IP network.](868ee7df1ec851f132ccf8c390de76a8_img.jpg)
+
+The diagram illustrates the IPCablecom multimedia architectural framework. It shows the following components and their interconnections:
+
+- Client**: Connected to a **Cable modem**. It has an interface labeled **mm-7\*** to the **Application manager** and **pkt-mm-6** to the **CMTS**.
+- Cable modem**: Connected to the **Client** and the **CMTS**. It has an interface labeled **pkt-mm-1** to the **CMTS**.
+- CMTS**: Connected to the **Cable modem** and the **Policy server**. It has interfaces labeled **pkt-mm-2** to the **Policy server**, **pkt-mm-5** to the **Record keeping server**, and **mm-10\*** to the **Operator-managed IP network**.
+- Policy server**: Connected to the **CMTS** and the **Record keeping server**. It has an interface labeled **pkt-mm-3** to the **Record keeping server** and **mm-9\*** to the **Operator-managed IP network**.
+- Record keeping server**: Connected to the **Policy server** and the **Application manager**. It has an interface labeled **pkt-mm-4** to the **Application manager**.
+- Application manager**: Connected to the **Record keeping server** and the **Operator-managed IP network**. It has an interface labeled **mm-8\*** to the **Operator-managed IP network**.
+- Operator-managed IP network**: Represented by a cloud, it is connected to the **Application manager**, **CMTS**, and **Policy server**.
+
+Interfaces marked with an asterisk (\*) indicate they are out of scope.
+
+Diagram of the IPCablecom multimedia architectural framework showing the flow of data and control signals between a Client, Cable modem, CMTS, Policy server, Record keeping server, Application manager, and Operator-managed IP network.
+
+**Figure I.2/J.179 – IPCablecom multimedia architectural framework**
+
+In this architecture, Clients may or may not support the IPCablecom Multimedia framework. Clients that support the framework and its QoS signalling mechanisms explicitly issue requests for network resources on their own behalf, which are authorized at the head-end by the Policy Server. Clients that do not support the QoS signalling mechanisms have network resource requests proxied on their behalf by an Application Manager, with which they interact.
+
+Regardless of the QoS signalling method, access-network resource requests are always subject to policy control, which is enforced at the Cable Modem Termination System (CMTS) serving as a Policy Enforcement Point (PEP) and defined at the Policy Server (PS), serving as a Policy Decision Point (PDP).
+
+- Policy decisions may be pulled from the Policy Server by the CMTS. In this case, the CMTS typically issues a policy request as the result of a currently unauthorized, yet
+
+conformant QoS resource request. Based on the resulting decision, the original QoS request is serviced or rejected.
+
+- Alternatively, policy decisions may be pushed to the CMTS by the Policy Server. In this case, the Policy Server shall install a policy decision in advance of a QoS resource request based on a policy request originating from an Application Manager. An Application Manager generates such a request, based on Client interaction (through some unspecified signalling mechanism).
+
+Both the Policy Server and the CMTS generate event messages to track QoS requests and usage. These event messages are sent to a Record Keeping Server (RKS) where they may be used for billing or other accounting purposes.
+
+Table I.1 summarizes the interfaces presented in Figure I.2. Interfaces that are defined by this Recommendation are labelled "pkt-mm-x", while other interfaces, which are included for completeness, are labelled "mm-x".
+
+**Table I.1/J.179 – IPCablecom multimedia interfaces**
+
+| Interface | Description   | Notes                                                                                                                                                                                                                                                                                                                                                                                                             |
+|-----------|---------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| pkt-mm-1  | CMTS – CM     | The CM may request QoS from the CMTS via CableModem DSx signalling. Alternatively, the CMTS may instruct the Cable Modem (CM) to set up, tear down or change a CableModem service flow in order to satisfy a QoS request, again via DSx signalling.                                                                                                                                                               |
+| pkt-mm-2  | PS – CMTS     | This interface is fundamental to the policy-management framework. It controls policy decisions, which may be:<br>a) pushed by the Policy Server (PS) onto the CMTS, or<br>b) pulled from the PS by the CMTS.<br><br>The interface also allows for proxied QoS requests on behalf of a client.<br><br>In some scenarios, this interface may also be used to inform the PS when QoS resources have become inactive. |
+| pkt-mm-3  | AM – PS       | The Application Manager (AM) may request that the PS install a policy decision on the CMTS. Additionally, the AM may also request that the PS proxy QoS requests to the CMTS on behalf of the client.<br><br>This interface may also be used to inform the AM of changes in the status of QoS resources.                                                                                                          |
+| pkt-mm-4  | PS – RKS      | The PS sends event messages to the Record Keeping Server (RKS) to track policy decisions related to QoS.                                                                                                                                                                                                                                                                                                          |
+| pkt-mm-5  | CMTS – RKS    | The CMTS sends the RKS event messages to track requests for and usage of QoS (e.g., service flow adds, changes, deletes, and volume metrics).                                                                                                                                                                                                                                                                     |
+| pkt-mm-6  | Client – CMTS | The client may use this interface to directly request and manage QoS network resources. If authorized, these resources are provided by the CMTS.                                                                                                                                                                                                                                                                  |
+| mm-7      | Client – AM   | This interface may be used by the client to interact with the AM and to indirectly request and manage QoS resources. This interface is out of the scope of this appendix.                                                                                                                                                                                                                                         |
+
+**Table I.1/J.179 – IPCablecom multimedia interfaces**
+
+| Interface | Description                        | Notes                                                                                                                                                                  |
+|-----------|------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| mm-8      | AM – Peer                          | The AM may use this interface to interact with some other entity that is part of the application in question. This interface is out of the scope of this appendix.     |
+| mm-9      | CMTS – operator-Managed IP Network | This interface on the CMTS may be used in support of end-to-end QoS requests beyond the access network. This interface is out of the scope of this appendix.           |
+| mm-10     | Client – Peer                      | The Client may use this interface to interact with some other entity that is part of the application in question. This interface is out of the scope of this appendix. |
+
+### I.3.2 Multimedia components
+
+In this clause, we expand on the previous discussion regarding the architectural framework by providing additional detail for each of the network elements.
+
+#### I.3.2.1 Client
+
+A multimedia client is a logical entity that may send or receive data. IPCablecom Multimedia defines three different client types, which differ in how the client signals QoS and how the policy decisions associated with the QoS are installed in the CMTS.
+
+Client Type 1 represents existing "legacy" endpoints (e.g., PC applications, gaming consoles) which lack specific QoS awareness or signalling capabilities. This Client knows nothing about CableModem, IPCable2Home, or IPCablecom messaging, and hence no related requirements can be placed upon it. Such clients may range from simple analog audio and video presentation devices to complex networked peripherals and consumer electronics, such as set-top boxes or gaming consoles. This Client communicates with an Application Manager to request service, and does not request QoS resources directly from the operator access network.
+
+Client Type 2 is similar to an IPCablecom-T telephony MTA in that it supports QoS signalling based on IPCablecom DQoS. This Client is aware of IPCablecom Multimedia QoS, and communicates with an Application Manager to request service and obtain a token for access-network resources. The client then presents this token when requesting QoS resources from the access network (pkt-mm-1, pkt-mm-6).
+
+Client Type 3 requests QoS based on RSVP without Application Manager interaction. This Client is aware of IETF standards-based RSVP and uses this protocol to request QoS resources from the access network directly from the CMTS.
+
+#### I.3.2.2 Policy server
+
+The policy-management framework for the IPCablecom Multimedia initiative is based upon the work of the IETF's Resource Allocation Protocol (RAP) working group. As defined and described in RFC 2753, the Policy Server (PS) network element implements operator-defined authorization and resource-management procedures. In addition to the requested resource parameters and the status of available resources, policy decisions may involve client identity and associated profile information, application parameters, security considerations, time-of-day, etc. Also, particular operators may elect to deploy multiple Policy Servers and delegate certain policy decisions among these servers in order to satisfy scalability and fault-tolerance requirements.
+
+The main functions of the Policy Server include:
+
+- A policy decision request mechanism, invoked by Application Managers (pkt-mm-3, push model) or CMTSs (pkt-mm-2, pull model);
+
+- A policy decision delivery mechanism, used to install policy decisions on the CMTS (pkt-mm-2);
+- A mechanism to allow for the proxying of QoS management messages to the CMTS on behalf of the Application Manager (for clients who do not have native QoS signalling capabilities);
+- An event recording interface to a Record Keeping Server (pkt-mm-4) used to log policy requests, which may also be correlated with network resource usage records.
+
+The Policy Server may support two different models for installing policy decisions on the CMTS:
+
+- The Policy Server may install (push) a policy decision on the CMTS before a QoS reservation request arrives at the CMTS.
+- The CMTS may request (pull) a policy decision from the Policy Server when a QoS reservation request arrives at the CMTS.
+
+Policy rules may contain the following information:
+
+- Rules defining resources authorized by the policy server:
+  - Per-service;
+  - Per-subscriber;
+  - Bandwidth (specified using token-bucket parameters);
+  - Latency guarantees;
+  - Policy expiration times;
+  - Policy volume limits.
+- Rules defining scarcity/value of bandwidth based on time of day.
+- Pre-emption rules.
+
+At a minimum, under the "push" scenario the policy server must perform the following functions:
+
+- Authenticate and verify policy messages from Application Managers;
+- Process policy messages based on operator-defined rules;
+- Resolve the correct identity of the CMTS to which policy is to be pushed;
+- Communicate policy decisions and other messages securely with the CMTS;
+- Send event messages tracking these requests to the RKS.
+
+At a minimum, under the "pull" scenario the policy server must perform the following functions:
+
+- If an Application Manager is involved in the service, authenticate and verify policy messages from the Application Manager;
+- Communicate policy decisions and other messages securely with the CMTS;
+- Process policy messages based on operator-defined rules;
+- Send event messages tracking these requests to the RKS.
+
+The policy server may perform the following additional functions:
+
+- Track resource usage based on internally-maintained state information (e.g., timers);
+- Track authorized resources on per-user, per-service, or aggregate basis.
+
+#### **I.3.2.3 Cable modem termination system**
+
+IPCablecom Multimedia provides access to the full set of CMTS upstream scheduling algorithms as defined in the CableModem Recommendations. Specifically, the architecture defines an IPCablecom Multimedia "Traffic Profile" that provides a layer of abstraction from associated CableModem Scheduling Types (UGS, UGS/AD, etc.). Further, the telephony-specific features and
+
+assumptions found in the IPCablecom-T DQoS specification will be generalized to provide a QoS infrastructure that can be used by multiple types of clients and applications.
+
+The CMTS supports both single and two-phase reservation models for managing access-network resources. In the two-phase model, access-network resources are initially reserved, then committed for use as they are required at a later time. The CMTS also supports a single-phase reservation model in which access-network resources are simultaneously reserved and committed for immediate use.
+
+The CMTS sets up the relevant service flow(s) on the CableModem access network via pkt-mm-1. The CMTS sends event messages for QoS resource reservations and usage to a Record Keeping Server via pkt-mm-5 interface identifier. Finally, the CMTS monitors QoS-based service flows and accounts for them as defined in the (optional) Account Management subsystem in the CableModem Recommendations.
+
+#### **I.3.2.4 Application manager**
+
+The Application Manager plays a coordinating role involving application signalling and semantics as well as interaction with the IPCablecom Multimedia policy framework, as outlined during the previous discussion of the Policy Server element. Note that an Application Manager may be co-hosted with a Media Server or, under a divided model, the two elements may exist separately.
+
+The Application Manager interfaces with a client via mm-7. Based on its knowledge of particular service offerings, the Application Manager must infer or define the particular QoS parameters necessary to deliver the service to Client Type 1. Once this information has been ascertained, the Application Manager sends a policy request to the Policy Server via pkt-mm-3. If necessary, the Application Manager may use mm-8 to synchronize with a Media Server.
+
+Client Type 2 also interacts with the Application Manager and communicates service request information via mm-7. Again, the Application Manager must infer the QoS parameters necessary to deliver the service to Client Type 2. The Application Manager sends a policy request to the Policy Server via pkt-mm-3. Upon successful authorization, the Application Manager receives a token from the Policy Server and sends the token to the Client via mm-7. If necessary, the Application Manager may use mm-8 to synchronize with a Media Server.
+
+Client Type 3 does not require an Application Manager, although the presence of an Application Server in sophisticated service delivery scenarios is quite likely.
+
+#### **I.3.2.5 Record keeping server**
+
+The Record Keeping Server (RKS) receives event messages indicating the usage of access-network QoS resources. The RKS interfaces with the Policy Server (pkt-mm-4) and the CMTS (pkt-mm-5). The RKS does not receive application-specific information directly from the Application Manager. Instead, application-specific information may be included in an event message as opaque data sent from the Application Manager to the Policy Server and embedded in the policy request event message to the RKS.
+
+## **I.4 Proxied QoS with policy push (Scenario 1)**
+
+As noted above, three architectural scenarios have been identified in support of the three client types. The "proxied-QoS with policy-push" authorization model (Scenario 1) supports Client Type 1, which does not itself support native QoS signalling mechanisms. A high-level overview of the element interaction involved in this scenario is shown in Figure I.3.
+
+The Client requests an application-specific service by sending a "Service Request" to the Application Manager. Upon receipt of this request, the Application Manager determines the QoS needs of the requested service and sends a "Policy Request" to the Policy Server. The Policy Server in turn validates the "Policy Request" against the operator-defined policy rules and, if the decision
+
+is affirmative, sends a "Policy Set" message to the CMTS. The CMTS performs admission control on the requested QoS envelope (verifying that adequate resources are available to satisfy this request), installs the policy decision, and (eventually) establishes the service flow(s) with the requested QoS levels.
+
+It should be noted that the actual management of the service flow(s) (i.e., add, change, delete requests) may be closely controlled and monitored by the Application Manager through extensions to the basic signalling mechanisms outlined here for the installation of the policy decision. In Scenario 1, there is no direct communication between the Client and the CMTS.
+
+Note that the interface between the Client and Application Manager, including the details of the "Service Request," are out of the scope of this Recommendation. It is possible that the Client has no knowledge of QoS and simply requests service (e.g., the user wants to play a multi-player game with a friend) from the Application Manager in the "Service Request" message. It is also possible that the Client has full knowledge of its QoS requirements (e.g., the user requests guaranteed 128 kbit/s service for access to his corporate VPN, secured by IPSec) and communicates this additional information in the "Service Request". The mechanism by which the Application Manager determines the QoS requirements for the requested service is out of the scope of this architecture.
+
+![Diagram of the Authorization framework for Scenario 1. It shows four entities: Application manager, Policy server, CMTS, and Client. The flow is: Client sends a 'Service request' to the Application manager. The Application manager sends a 'Policy request' to the Policy server. The Policy server sends a 'Policy set' to the CMTS.](245166735676c675f98f535bc4c6f0a1_img.jpg)
+
+```
+graph LR; Client -- "Service request" --> Application_manager[Application manager]; Application_manager -- "Policy request" --> Policy_server[Policy server]; Policy_server -- "Policy set" --> CMTS;
+```
+
+J.179\_FI.3
+
+Diagram of the Authorization framework for Scenario 1. It shows four entities: Application manager, Policy server, CMTS, and Client. The flow is: Client sends a 'Service request' to the Application manager. The Application manager sends a 'Policy request' to the Policy server. The Policy server sends a 'Policy set' to the CMTS.
+
+**Figure I.3/J.179 – Authorization framework for Scenario 1**
+
+Under Scenario 1, the CMTS supports a single-phase resource reservation model, as shown in Figure I.4, to enable immediate activation and usage of access-network resources by the Client. (A two-phase resource reservation model is also supported under this scenario as outlined later in this clause.)
+
+![Sequence diagram for single-phase resource reservation model for Scenario 1. The diagram shows interactions between Client type 1, Application manager, Policy server, Cable Modem Termination System (CMTS), Cable Modem (CM), and RKS. The sequence is: (1) Service request from Client type 1 to Application manager; (2) Policy Request from Application manager to Policy server; (3) Policy set from Policy server to CMTS; (4) DOCSIS service flow messaging from CMTS to CM; (5) QoS event (reserve/commit) from CMTS to RKS; (6) Policy event from Policy server to RKS. Connections are labeled IP between Policy server and CMTS, and HFC between CMTS and CM. A label J.179_F1.4 is near the CM box.](4ef412e08808c40e0beb7808d36b9379_img.jpg)
+
+Sequence diagram for single-phase resource reservation model for Scenario 1. The diagram shows interactions between Client type 1, Application manager, Policy server, Cable Modem Termination System (CMTS), Cable Modem (CM), and RKS. The sequence is: (1) Service request from Client type 1 to Application manager; (2) Policy Request from Application manager to Policy server; (3) Policy set from Policy server to CMTS; (4) DOCSIS service flow messaging from CMTS to CM; (5) QoS event (reserve/commit) from CMTS to RKS; (6) Policy event from Policy server to RKS. Connections are labeled IP between Policy server and CMTS, and HFC between CMTS and CM. A label J.179\_F1.4 is near the CM box.
+
+**Figure I.4/J.179 – Single-phase resource reservation model for Scenario 1**
+
+Based on this single-phase messaging sequence, Table I.2 provides a high-level summary of each of these messages. Details specific to protocol messages and objects have been deferred to the respective IPCablecom Multimedia specifications.
+
+**Table I.2/J.179 – Single-phase resource reservation message details for Scenario 1**
+
+| Message             | Function                                                            | Fields                                                                                                                           | Protocol candidate                        | Comments                                                                                                                                                                                                                       |
+|---------------------|---------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| (1) Service Request | The Client requests service from the Application Manager.           | <none>                                                                                                                           | Out of the scope of IPCablecom Multimedia | This protocol should support the authentication of both Client and Application Manager. Also, the protocol should provide sufficient information for the Application Manager to convey the QoS needs of the requested service. |
+| (2) Policy Request  | The Application Manager requests QoS setup on behalf of the client. | IP Cablecom MM QoS Type, IP Cablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint | Gate-Control (COPS)                       | The Policy Server uses operator-managed policy rules to allow or disallow the request.                                                                                                                                         |
+
+**Table I.2/J.179 – Single-phase resource reservation message details for Scenario 1**
+
+| <b>Message</b>           | <b>Function</b>                                                                                                          | <b>Fields</b>                                                                                                                                                                                        | <b>Protocol candidate</b> | <b>Comments</b>                                                                                                                                                                                             |
+|--------------------------|--------------------------------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| (3) Policy Set           | The Policy Server sends a message to the CMTS, installing its policy decision and requesting service flow establishment. | IPCablecom MM QoS Type, IPCablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint (for both AM and PS)                                                  | Gate-Control (COPS)       | Under the single-phase model, this request is for authorization, reservation and commitment of the QoS resources.                                                                                           |
+| (4) CableModem Messaging | The CMTS establishes QoS-enhanced service flows.                                                                         | CableModem Scheduling Type, Bandwidth and Latency Parameters, Traffic Classifier                                                                                                                     | CableModem DSx Messaging  | The QoS functions here are based on the mechanisms defined in the CableModem RFI specification.                                                                                                             |
+| (5) QoS Event            | The CMTS generates the proper event message, indicating QoS usage and other billing parameters                           | IPCablecom MM QoS Type, IPCablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint (for both AM and PS) Policy Decision, Service Usage Data, Time-of-Day | Event-Messaging (RADIUS)  | This message should contain sufficient constructs to allow for a reconstruction of the event(s) and decision(s) made with regard to a particular service for the purposes of support and/or reconciliation. |
+| (6) Policy Event         | The Policy Server generates the proper event message, indicating the Policy Request and action taken.                    | IPCablecom MM QoS Type, IPCablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint (for both AM and PS), Policy Decision                                 | Event-Messaging (RADIUS)  | This message should contain sufficient constructs to allow for a reconstruction of the event(s) and decision(s) made with regard to a particular service for the purposes of support and/or reconciliation. |
+
+The information summarized in the Fields column in Table I.2 is intended to provide an example of the type of information carried by each message. The details of each protocol message have been deferred to the appropriate specification documents.
+
+Scenario 1 also supports a two-phase resource reservation model, as shown in Figure I.5. Here, the Application Manager first asks for access-network QoS resources to be authorized and reserved. Once these resources have been reserved, the Application Manager may continue its dialogue with the Client concerning the service. When appropriate, the Application Manager asks for access-network QoS resources to be committed. This two-phase reserve/commit model guarantees that access-network resources are available before offering service to the Client.
+
+Note that acknowledgements for each of the messages shown are not explicitly included, but are implied. Each acknowledgement message can only be sent once the final outcome of the corresponding request is known. This is particularly important in the sequencing of acknowledgements of messages 5 (DOCSIS Reserve), 3 (Policy Set), and 2 (Policy Request) since the Application manager will likely wait for successful confirmation of the reservation phase before continuing its dialog with the Client and eventually committing the resources.
+
+![Sequence diagram of the two-phase resource reservation model for Scenario 1. The diagram shows interactions between Client type 1, Application manager, Policy server, Cable Modem Termination System (CMTS), Cable Modem (CM), and RKS. The sequence starts with a Service request (1) from Client type 1 to Application manager. The Application manager sends a Policy request (2) to the Policy server. The Policy server responds with a Policy set (3) to the Application manager. The Application manager sends a QoS commit (7) to the Policy server. The Policy server sends a Policy event (6) and a Commit event (11) to the RKS. The RKS sends a QoS event (Reserve) (5) and a QoS event (Commit) (10) to the CMTS. The CMTS sends a QoS commit (proxied) (8) to the Policy server. The CMTS sends a DOCSIS reserve (4) and a DOCSIS commit (9) to the CM. The CM sends a J.179_FL5 message to the CMTS. The CMTS is connected to the Policy server via IP and to the CM via HFC.](cf03eff1218a8cc1be6b05de892162de_img.jpg)
+
+Sequence diagram of the two-phase resource reservation model for Scenario 1. The diagram shows interactions between Client type 1, Application manager, Policy server, Cable Modem Termination System (CMTS), Cable Modem (CM), and RKS. The sequence starts with a Service request (1) from Client type 1 to Application manager. The Application manager sends a Policy request (2) to the Policy server. The Policy server responds with a Policy set (3) to the Application manager. The Application manager sends a QoS commit (7) to the Policy server. The Policy server sends a Policy event (6) and a Commit event (11) to the RKS. The RKS sends a QoS event (Reserve) (5) and a QoS event (Commit) (10) to the CMTS. The CMTS sends a QoS commit (proxied) (8) to the Policy server. The CMTS sends a DOCSIS reserve (4) and a DOCSIS commit (9) to the CM. The CM sends a J.179\_FL5 message to the CMTS. The CMTS is connected to the Policy server via IP and to the CM via HFC.
+
+**Figure I.5/J.179 – Two-phase resource reservation model for Scenario 1**
+
+A summary of the messages outlined in Figure I.5 is provided in Table I.3 below. Note that messages (7-10) are added in support of the commit signalling phase.
+
+**Table I.3/J.179 – Two-phase resource reservation message details for Scenario 1**
+
+| Message             | Function                                                  | Fields | Protocol candidate                        | Comments                                                                                                                                                                                                                  |
+|---------------------|-----------------------------------------------------------|--------|-------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| (1) Service Request | The Client requests service from the Application Manager. | <none> | Out of the scope of IPCablecom Multimedia | This protocol should support the authentication of Client and Application Manager. Also, the protocol should provide sufficient information for the Application Manager to convey the QoS needs of the requested service. |
+
+**Table I.3/J.179 – Two-phase resource reservation message details for Scenario 1**
+
+| Message            | Function                                                                                                               | Fields                                                                                                                                                                                                 | Protocol candidate       | Comments                                                                                                                                                                                                    |
+|--------------------|------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| (2) Policy Request | The Application Manager requests QoS setup on behalf of the client.                                                    | IP Cablecom MM QoS Type, IP Cablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint                                                                       | Gate-Control (COPS)      | The Policy Server uses operator-managed policy rules to allow or disallow the request.                                                                                                                      |
+| (3) Policy Set     | The Policy Server sends a message to the CMTS, installing its policy decision and requesting service flow reservation. | IP Cablecom MM QoS Type, IP Cablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint (for both AM and PS)                                                  | Gate-Control (COPS)      | Under the two-phase model, this request is for authorization and reservation of the QoS resources.                                                                                                          |
+| (4) DOCSIS Reserve | The CMTS establishes QoS-enhanced service flows and places them in an "admitted" state.                                | CableModem Scheduling Type, Bandwidth and Latency Parameters, Traffic Classifier                                                                                                                       | CableModem DSx Messaging | The QoS functions here are based on the mechanisms defined in the CableModem RFI specification. Reserved resources remain inactive and may be used by best-effort traffic on other flows until committed.   |
+| (5) QoS Event      | The CMTS generates the proper event message, indicating the QoS reservation and other billing parameters.              | IP Cablecom MM QoS Type, IP Cablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint (for both AM and PS) Policy Decision, Service usage data, Time-of-day | Event-Messaging (RADIUS) | This message should contain sufficient constructs to allow for a reconstruction of the event(s) and decision(s) made with regard to a particular service for the purposes of support and/or reconciliation. |
+| (6) Policy Event   | The Policy Server generates the proper event message, indicating the Policy Request and action taken.                  | IP Cablecom MM QoS Type, IP Cablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint (for both AM and PS) Policy Decision                                  | Event-Messaging (RADIUS) | This message should contain sufficient constructs to allow for a reconstruction of the event(s) and decision(s) made with regard to a particular service for the purposes of support and/or reconciliation. |
+
+**Table I.3/J.179 – Two-phase resource reservation message details for Scenario 1**
+
+| Message                  | Function                                                                                            | Fields                                                                                                                                                                                                 | Protocol candidate       | Comments                                                                                                                                                                                                    |
+|--------------------------|-----------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| (7) QoS Commit           | The AM signals to commit the QoS resources.                                                         | IP Cablecom MM QoS Type, IP Cablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Policy Identifier                                                                         | Gate-Control (COPS)      | The AM commitment may depend on further messaging with the client.                                                                                                                                          |
+| (8) QoS Commit (Proxied) | The Policy Server receives the AM request and proxies to the CMTS.                                  | IP Cablecom MM QoS Type, IP Cablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Policy Identifier                                                                         | Gate-Control (COPS)      | Even though the PS may apply policy rules during the commit phase, it is generally assumed that the reserved bandwidth may be committed at any time by the AM.                                              |
+| (9) DOCSIS Commit        | The CMTS places the service flow in the "active" state.                                             | CableModem Scheduling Type, Bandwidth and Latency Parameters, Traffic Classifier, Service Flow ID                                                                                                      | CableModem DSx Messaging | The QoS functions here are based on the mechanisms defined in the CableModem RFI specification.                                                                                                             |
+| (10) QoS Event (Commit)  | The CMTS generates the proper event message, indicating the QoS usage and other billing parameters. | IP Cablecom MM QoS Type, IP Cablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint (for both AM and PS) Policy Decision, Service usage data, Time-of-day | Event Messaging (RADIUS) | This message should contain sufficient constructs to allow for a reconstruction of the event(s) and decision(s) made with regard to a particular service for the purposes of support and/or reconciliation. |
+| (11) Commit Event        | The Policy Server generates the proper event message, indicating the QoS commit and action taken.   | IP Cablecom MM QoS Type, IP Cablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Policy Identifier                                                                         | Event Messaging (RADIUS) | This message should contain sufficient constructs to allow for a reconstruction of the event(s) and decision(s) made with regard to a particular service for the purposes of support and/or reconciliation. |
+
+Once QoS resources have been successfully authorized, reserved, and committed on the access network, these resources are monitored for activity at the CMTS. In general, a soft-state model is used in which periodic refresh messages are required during periods of inactivity on reserved and committed service flows. If activity timers expire without a refresh, the associated resources may be recovered by the CMTS. This provides for network resilience in the case of a failed endpoint.
+
+A more standard resource recovery sequence is also provided under this scenario in which the Application Manager signals the Policy Server when the service session has ended. The Policy
+
+Server responds by generating an event message, which is sent to the RKS, and issuing a directive to the CMTS to tear-down the associated service flow(s) and recover associated resources. Regardless of whether a service flow times-out due to inactivity or is explicitly deleted, a robust audit trail is maintained, tracking actual resource usage via event messages produced at the CMTS and sent to the RKS.
+
+### **I.4.1 Example: Web-based bandwidth on demand**
+
+One example of how the mechanisms in Scenario 1 may be applied in a service delivery context is the case of an operator-hosted secure website which would allow subscribers to request bandwidth reservations on-demand.
+
+Assume, for example, that a subscriber's normal service is rate limited to 128 kbit/s downstream and 128 kbit/s upstream. While this level of service may be adequate for most usage, there may be times when the application the subscriber is using requires more bandwidth or has different QoS needs. If the user decides to use the bandwidth on-demand service to make temporary changes to their normal service level, they would simply login to the operator's website (Application Manager) and request a temporary service upgrade.
+
+One possible motivation for such a request would be the desire to stream high bit rate media files from a content provider. In this case, the subscriber might explicitly request 512 kbit/s downstream minimum reserved rate service for the next three hours. Alternatively, the exact QoS needs of the application might be opaque to the subscriber, who might simply request a given three-hour video clip (which, unbeknownst to the subscriber, happens to be encoded at 512 kbit/s). Either way, this exchange represents the subscriber's "Service Request" to the Application Manager.
+
+In the either case, the Application Manager would present a "Policy Request" for 512 kbit/s minimum reserved rate service for three hours to the Policy Server on behalf of the subscriber. The Policy Server would then apply its own authorization criteria and, if the request was approved, ask the CMTS (through a "Policy Set") to provide the bandwidth for the subscriber. The CMTS would, in turn, perform internal admission control and establish the QoS using the CableModem messaging, tracking this process through a QoS event message.
+
+### **I.4.2 Example: Online gaming via networked consoles**
+
+Alternatively, consider a case in which two gaming consoles wish to engage one another via a network tunnel. In this example, two users may typically network their consoles only if they are co-located. However, special software installed on each user's Personal Computer, collocated on a local network and serving as a proxy for the remote console, enables networking such that two gaming consoles no longer need to be co-located. The only problem with this novel approach is that the resulting tunnel requires sufficient QoS so that the gaming consoles can be played as if they were co-located on a high-speed network.
+
+In this scenario, the user(s) would connect to the Application Manager via the PC(s) that tunnel their packets. Through application-specific messaging, they authenticate themselves and indicate their request to play a game with one another. The Application Manager grants the request, and generates the "Policy Request(s)" on behalf of the user(s). The Policy Server makes its decision and relays the message as a "Policy Set" to the CMTS. The CMTS performs admission control and enables access network QoS between the PCs for the gaming tunnel using CableModem messaging. From this point on, the gaming consoles may exchange packets without knowing that they are not co-located. Note that Event Messaging has been omitted from this example for simplicity.
+
+In this hypothetical example, if the users reside on separate HFC nodes, it is the operator's responsibility to ensure that backbone QoS to and from the CMTS is handled properly at the level that their policy and service agreements require. Figure I.6 provides a graphical illustration of this example for the simplified case in which both users receive service from a single CMTS.
+
+![Diagram illustrating the network architecture for gaming consoles connected via a QoS-enhanced IP tunnel. Two PCs, each connected to a Gaming console, are linked by a 'Gaming tunnel' through a central CMTS. The PCs send 'Game request' messages to an 'Application manager', which in turn sends a 'Policy request' to a 'Policy server'. The 'Policy server' sends a 'Policy set' to the 'CMTS'. The 'CMTS' then sends 'Gaming packets' to the PCs, which are then passed to the Gaming consoles. The diagram is labeled J.179_F1.6.](143c8ee1010bf7669caabfbed815df1b_img.jpg)
+
+```
+
+graph TD
+    subgraph LeftSide [ ]
+        PC1[PC]
+        Console1[Gaming console]
+        PC1 -- "Gaming packets" --> Console1
+    end
+    subgraph RightSide [ ]
+        PC2[PC]
+        Console2[Gaming console]
+        PC2 -- "Gaming packets" --> Console2
+    end
+    PC1 -- "Game request" --> AM[Application manager]
+    PC2 -- "Game request" --> AM
+    AM <--> "Policy request" --> PS[Policy server]
+    PS <--> "Policy set" --> CMTS[CMTS]
+    CMTS -- "Gaming tunnel" --> PC1
+    CMTS -- "Gaming tunnel" --> PC2
+    style LeftSide fill:none,stroke:none
+    style RightSide fill:none,stroke:none
+  
+```
+
+Diagram illustrating the network architecture for gaming consoles connected via a QoS-enhanced IP tunnel. Two PCs, each connected to a Gaming console, are linked by a 'Gaming tunnel' through a central CMTS. The PCs send 'Game request' messages to an 'Application manager', which in turn sends a 'Policy request' to a 'Policy server'. The 'Policy server' sends a 'Policy set' to the 'CMTS'. The 'CMTS' then sends 'Gaming packets' to the PCs, which are then passed to the Gaming consoles. The diagram is labeled J.179\_F1.6.
+
+**Figure I.6/J.179 – Gaming consoles networked via a QoS-enhanced IP tunnel**
+
+## I.5 Client-requested QoS with policy-push (Scenario 2)
+
+Scenario 2's "client-requested QoS with policy-push" model supports Client Type 2, which is capable of signalling and managing its own QoS resources but requires prior authorization of these requests via an Application Manager. In this scenario, the policy authorization and QoS reservation model closely resembles the IPCablecom-T telephony model defined in the DQoS specification. The Policy Server pushes policy to the CMTS in a manner similar to that in which the Gate Controller sends policy to the CMTS via COPS. Client Type 2 uses either CableModem DSx or RSVP+ messaging similar to MTA devices in IPCablecom-T.
+
+A high-level overview of Scenario 2 is shown in Figure I.7. Note the similarities to the authorization framework outlined for Scenario 1. Here again, the client requests an application-specific service by sending a "Service Request" to the Application Manager. The Application Manager then determines the QoS needs of the requested service and sends a "Policy Request" to the Policy Server. The "Policy Request" contains the "authorized envelope" or maximum QoS allowed for the client. The Policy Server in turn validates the "Policy Request" against the operator-defined policy rules and, if the decision is affirmative, sends a "Policy Set" to the CMTS. The CMTS performs admission control over the requested QoS and installs the policy authorization. As in Scenario 1, event messages are generated by the Policy Server and the CMTS and sent to the RKS. The Policy Server records an event any time it makes a decision, or updates its state, and the CMTS tracks QoS resource maintenance and usage.
+
+In Scenario 2 and unlike Scenario 1, there is direct communication between the Client and the CMTS in order to add, change and delete resource reservations. After the CMTS receives the "Policy Set" message from the Policy Server, the Client may request QoS directly from the CMTS using the previously noted QoS signalling mechanisms. The Client may also change the QoS dynamically as long as the requested QoS is within the "authorized envelope" approved by the Policy Server. The advantage of this method is that the Application Manager does not have to negotiate Client bandwidth utilization, which is a very useful factor when the Client's QoS needs change dynamically.
+
+![Figure I.7/J.179 – Authorization framework for Scenario 2. A block diagram showing four entities: Application manager, Policy server, CMTS, and Client. Arrows indicate the flow of messages: Service request (Client to Application manager), Policy request (Application manager to Policy server), Policy set (Policy server to CMTS), and QoS request (CMTS to Client).](9b6977f95ef47e2c87cd4979c09a7edb_img.jpg)
+
+```
+
+graph LR
+    Client -- "Service request" --> Application_manager["Application manager"]
+    Application_manager -- "Policy request" --> Policy_server["Policy server"]
+    Policy_server -- "Policy set" --> CMTS
+    CMTS -- "QoS request" --> Client
+    style Client stroke-width:1px
+    style Application_manager stroke-width:1px
+    style Policy_server stroke-width:1px
+    style CMTS stroke-width:1px
+
+```
+
+J.179\_FI.7
+
+Figure I.7/J.179 – Authorization framework for Scenario 2. A block diagram showing four entities: Application manager, Policy server, CMTS, and Client. Arrows indicate the flow of messages: Service request (Client to Application manager), Policy request (Application manager to Policy server), Policy set (Policy server to CMTS), and QoS request (CMTS to Client).
+
+**Figure I.7/J.179 – Authorization framework for Scenario 2**
+
+As in the previous scenario, Scenario 2 (as shown in Figure I.8) supports a single-phase resource reservation model to enable immediate activation and usage of access-network resources by the client.
+
+![Figure I.8/J.179 – Single-phase resource reservation model for Scenario 2. A block diagram showing the interaction between Application manager, Client type 2, Policy server, Cable Modem Termination System (CMTS), Cable Modem (CM), and RKS. Numbered steps show the sequence of requests and events for resource reservation.](93bd00a00fa28558486f0664550699b1_img.jpg)
+
+```
+
+graph TD
+    Client_type_2["Client type 2"] -- "(1) Service request" --> Application_manager["Application manager"]
+    Application_manager -- "(2) Policy request" --> Policy_server["Policy server"]
+    Policy_server -- "(3) Policy set" --> CMTS["Cable Modem Termination System (CMTS)"]
+    Policy_server -- "(4) Policy event" --> RKS
+    Client_type_2 -- "(5) QoS request (reserve/commit)" --> CMTS
+    CMTS -- "(6) DOCSIS service flow messaging" --> CM["Cable Modem (CM)"]
+    CMTS -- "(7) QoS event (reserve/commit)" --> RKS
+    Policy_server -- "IP" --- CMTS
+    CMTS -- "HFC" --- CM
+    style Client_type_2 stroke-width:1px
+    style Application_manager stroke-width:1px
+    style Policy_server stroke-width:1px
+    style CMTS stroke-width:1px
+    style CM stroke-width:1px
+    style RKS stroke-width:1px
+
+```
+
+J.179\_FI.8
+
+Figure I.8/J.179 – Single-phase resource reservation model for Scenario 2. A block diagram showing the interaction between Application manager, Client type 2, Policy server, Cable Modem Termination System (CMTS), Cable Modem (CM), and RKS. Numbered steps show the sequence of requests and events for resource reservation.
+
+**Figure I.8/J.179 – Single-phase resource reservation model for Scenario 2**
+
+Based on this single-phase messaging sequence, Table I.4 provides a high-level summary of each of these messages.
+
+**Table I.4/J.179 – Single-phase resource reservation message details for Scenario 2**
+
+| Message                          | Function                                                                                              | Fields                                                                                                                                                              | Protocol candidate                        | Comments                                                                                                                                                                                                                  |
+|----------------------------------|-------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| (1) Service Request              | The Client requests service from the Application Manager.                                             | <none>                                                                                                                                                              | Out of the scope of IPCablecom Multimedia | This protocol should support the authentication of Client and Application Manager. Also, the protocol should provide sufficient information for the Application Manager to convey the QoS needs of the requested service. |
+| (2) Policy Request               | The Application Manager requests QoS authorization on behalf of the Client.                           | IPCablecom MM QoS Type, IPCablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint                                      | Gate-Control (COPS)                       | The Policy Server uses operator-managed policy rules to allow or disallow the request.                                                                                                                                    |
+| (3) Policy Set                   | The Policy Server sends a message to the CMTS, installing its policy decision.                        | IPCablecom MM QoS Type, IPCablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint (for both AM and PS)                 | Gate-Control (COPS)                       | In this scenario, this request is for authorization only.                                                                                                                                                                 |
+| (4) Policy Event                 | The Policy Server generates the proper event message, indicating the Policy Request and action taken. | IPCablecom MM QoS Type, IPCablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint (for both AM and PS) Policy Decision | Event-Messaging (RADIUS)                  | This message should contain sufficient constructs to allow for a reconstruction of the event(s) and decision(s) made with regard to a particular service for the purposes of support and/or reconciliation.               |
+| (5) QoS Request (Reserve/Commit) | The Client requests that QoS resources are reserved and immediately committed for use.                | Bandwidth and Latency Parameters, Traffic Classifier                                                                                                                | CableModem DSx or RSVP+                   | The Client may directly establish CableModem service flows via DSx messaging or may issue RSVP+ messages to establish these flows.                                                                                        |
+
+**Table I.4/J.179 – Single-phase resource reservation message details for Scenario 2**
+
+| <b>Message</b>       | <b>Function</b>                                                                                     | <b>Fields</b>                                                                                                                                                                                        | <b>Protocol candidate</b> | <b>Comments</b>                                                                                                                                                                                                                                                                             |
+|----------------------|-----------------------------------------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| (6) DOCSIS Messaging | The CMTS establishes QoS-enhanced service flows and places them in an "active" state.               | CableModem Scheduling Type, Bandwidth and Latency Parameters, Traffic Classifier                                                                                                                     | CableModem DSx Messaging  | This step is only necessary if RSVP+ signalling was provided to the CMTS in the previous message, otherwise service flows have already been setup and activated via CableModem DSx messaging. The QoS functions here are based on the mechanisms defined in the CableModem Recommendations. |
+| (7) QoS Event        | The CMTS generates the proper event message, indicating the QoS usage and other billing parameters. | IPCablecom MM QoS Type, IPCablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint (for both AM and PS) Policy Decision, Service usage data, Time-of-day | Event-Messaging (RADIUS)  | This message should contain sufficient constructs to allow for a reconstruction of the event(s) and decision(s) made with regard to a particular service for the purposes of support and/or reconciliation.                                                                                 |
+
+The CMTS also supports a two-phase resource reservation model, as shown in Figure I.9. In this model, the Client first asks for access-network QoS resources to be reserved. Once these resources have been reserved, the Client then signals for these QoS resources to be committed. The two-phase reserve/commit model guarantees that access-network resources are available before offering services to the client.
+
+![Sequence diagram showing the two-phase resource reservation model for Scenario 2. The diagram involves four main entities: Application manager, Client type 2, Policy server, and Cable Modem Termination System (CMTS), and Cable Modem (CM). The sequence of messages is: (1) Service request from Client type 2 to Application manager; (2) Policy request from Application manager to Policy server; (3) Policy set from Policy server to CMTS; (4) Policy event from Policy server to RKS; (5) QoS request (Reserve) from Client type 2 to CMTS; (6) DOCSIS reserve from CM to CMTS; (7) QoS event (Reserve) from CMTS to RKS; (8) QoS request (Commit) from Client type 2 to CMTS; (9) DOCSIS commit from CM to CMTS; (10) QoS event (Commit) from CMTS to RKS. Connections are labeled IP between Policy server and CMTS, and HFC between CMTS and CM.](beda549cc2a4e2b9ac7f74fe9ed72b67_img.jpg)
+
+Sequence diagram showing the two-phase resource reservation model for Scenario 2. The diagram involves four main entities: Application manager, Client type 2, Policy server, and Cable Modem Termination System (CMTS), and Cable Modem (CM). The sequence of messages is: (1) Service request from Client type 2 to Application manager; (2) Policy request from Application manager to Policy server; (3) Policy set from Policy server to CMTS; (4) Policy event from Policy server to RKS; (5) QoS request (Reserve) from Client type 2 to CMTS; (6) DOCSIS reserve from CM to CMTS; (7) QoS event (Reserve) from CMTS to RKS; (8) QoS request (Commit) from Client type 2 to CMTS; (9) DOCSIS commit from CM to CMTS; (10) QoS event (Commit) from CMTS to RKS. Connections are labeled IP between Policy server and CMTS, and HFC between CMTS and CM.
+
+J.179\_F1.9
+
+**Figure I.9/J.179 – Two-phase resource reservation model for Scenario 2**
+
+**Table I.5/J.179 – Two-phase resource reservation message details for Scenario 2**
+
+| Message             | Function                                                                       | Fields                                                                                                                                              | Protocol Candidate                        | Comments                                                                                                                                                                                                                  |
+|---------------------|--------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| (1) Service Request | The Client requests service from the Application Manager.                      | <none>                                                                                                                                              | Out of the scope of IPCablecom Multimedia | This protocol should support the authentication of Client and Application Manager. Also, the protocol should provide sufficient information for the Application Manager to convey the QoS needs of the requested service. |
+| (2) Policy Request  | The Application Manager requests QoS authorization on behalf of the Client.    | IPCablecom MM QoS Type, IPCablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint                      | Gate-Control (COPS)                       | The Policy Server uses operator-managed policy rules to allow or disallow the request.                                                                                                                                    |
+| (3) Policy Set      | The Policy Server sends a message to the CMTS, installing its policy decision. | IPCablecom MM QoS Type, IPCablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint (for both AM and PS) | Gate-Control (COPS)                       | In this scenario, this request is for authorization only.                                                                                                                                                                 |
+
+**Table I.5/J.179 – Two-phase resource reservation message details for Scenario 2**
+
+| Message                   | Function                                                                                              | Fields                                                                                                                                                                                                  | Protocol Candidate       | Comments                                                                                                                                                                                                                                                                                    |
+|---------------------------|-------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| (4) Policy Event          | The Policy Server generates the proper event message, indicating the Policy Request and action taken. | IPCablecom MM QoS Type, IPCablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint (for both AM and PS)<br>Policy Decision                                  | Event-Messaging (RADIUS) | This message should contain sufficient constructs to allow for a reconstruction of the event(s) and decision(s) made with regard to a particular service for the purposes of support and/or reconciliation.                                                                                 |
+| (5) QoS Request (Reserve) | The Client requests that QoS resources are reserved.                                                  | Bandwidth and Latency Parameters, Traffic Classifier                                                                                                                                                    | CableModem DSx or RSVP+  | The Client may directly establish CableModem service flows via DSx messaging or may issue RSVP+ messages to establish these flows.                                                                                                                                                          |
+| (6) DOCSIS (Reserve)      | The CMTS establishes QoS-enhanced service flows and places them in an "admitted" state.               | CableModem Scheduling Type, Bandwidth and Latency Parameters, Traffic Classifier                                                                                                                        | CableModem DSx Messaging | This step is only necessary if RSVP+ signalling was provided to the CMTS in the previous message, otherwise service flows have already been setup and activated via CableModem DSx messaging. The QoS functions here are based on the mechanisms defined in the CableModem Recommendations. |
+| (7) QoS Event (Reserve)   | The CMTS generates the proper event message, indicating the QoS usage and other billing parameters.   | IPCablecom MM QoS Type, IPCablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint (for both AM and PS)<br>Policy Decision, Service usage data, Time-of-day | Event-Messaging (RADIUS) | This message should contain sufficient constructs to allow for a reconstruction of the event(s) and decision(s) made with regard to a particular service for the purposes of support and/or reconciliation.                                                                                 |
+
+**Table I.5/J.179 – Two-phase resource reservation message details for Scenario 2**
+
+| Message                  | Function                                                                                            | Fields                                                                                                                                                                                                      | Protocol Candidate       | Comments                                                                                                                                                                                                                                                                                    |
+|--------------------------|-----------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| (8) QoS Request (Commit) | The Client requests that QoS resources are committed.                                               | Bandwidth and Latency Parameters, Traffic Classifier                                                                                                                                                        | CableModem DSx or RSVP+  | The Client may directly establish CableModem service flows via DSx messaging or may issue RSVP+ messages to establish these flows.                                                                                                                                                          |
+| (9) DOCSIS (Commit)      | The CMTS places the service flows in an "active" state.                                             | CableModem Scheduling Type, Bandwidth and Latency Parameters, Traffic Classifier, Service Flow ID                                                                                                           | CableModem DSx Messaging | This step is only necessary if RSVP+ signalling was provided to the CMTS in the previous message, otherwise service flows have already been setup and activated via CableModem DSx messaging. The QoS functions here are based on the mechanisms defined in the CableModem Recommendations. |
+| (10) QoS Event (Commit)  | The CMTS generates the proper event message, indicating the QoS usage and other billing parameters. | IPCablecom MM QoS Type, IPCablecom MM Session Class, Bandwidth and Latency Parameters, Traffic Classifier, Opaque Billing Hint (for both AM and PS)<br><br>Policy Decision, Service usage data, Time-of-day | Event Messaging (RADIUS) | This message should contain sufficient constructs to allow for a reconstruction of the event(s) and decision(s) made with regard to a particular service for the purposes of support and/or reconciliation.                                                                                 |
+
+As in the previous scenario, two alternatives are possible with regard to QoS resource teardown and recovery. The resources may timeout (as detected at the CMTS) due to inactivity without a signalled timer refresh, or they may be explicitly deleted by the Client at the conclusion of a service session. The mechanism provided to explicitly signal service flow deletion is a component of the QoS protocol defined for Client Device 2. The only variation between the resource recovery sequence defined for Scenario 1 and that of Scenario 2 is that service flow deletion is signalled directly via the Client versus being proxied through the Application Manager in the second scenario.
+
+### I.5.1 Example: Online gaming via networked consoles
+
+The networked gaming console example outlined for Scenario 1 in I.4.2, may easily be altered to conform to the QoS resource management model presented in Scenario 2. In this case, the consoles would still coordinate with an Application Manager in order to locate one another and establish application-specific signalling. In addition, the Application Manager would submit a Resource Request to the Policy Server requesting authorization for necessary QoS resources. However, upon successful installation of this authorization decision on the CMTS, the Application Manager would simply return an affirmative acknowledgement containing an authorization token to each PC proxy. This token could then be used by the PCs in their QoS signalling to the CMTSs in order to reserve, commit, and delete the service flows required by the gaming tunnel.
+
+## I.6 Client-requested QoS with policy-pull (Scenario 3)
+
+The third scenario, with its "client-requested QoS with policy-pull" authorization model, supports Client Type 3. Scenario 3 defines a model in which policy authorization decisions are not pre-established and pushed to the CMTS via the Application Manager and Policy Server mechanisms outlined in the previous scenarios, but are requested on demand by the CMTS from the Policy Server as incoming reservation requests dictate. This allows for a very flexible and dynamic resource reservation model stimulated by the Client, while maintaining authoritative operator control at the head-end for all resource requests.
+
+In this scenario, the CMTS receives a QoS request from the Client prior to a policy decision being installed by the Policy Server. Included with this QoS request are credentials that enable the client to be authenticated. The CMTS constructs a policy request which it sends to the Policy Server. At the Policy Server, the request is authenticated and an authorization decision is made based upon operator-specified criteria (e.g., resource availability, customer profile, credit rating, service class, interaction with other network elements, etc.). If the policy authorization is successful, the resource reservation is allowed to proceed on the CMTS and the appropriate CableModem service flow are established based on the QoS requested. IPCablecom Multimedia interfaces (defined in I.3.1) involved in this interaction include: pkt-mm-1, pkt-mm-2, pkt-mm-4, pkt-mm-5, pkt-mm-6, and mm-9. The pkt-mm-3 interface may be used as well as specific application signalling requirements dictate, but it is not assumed to be in use.
+
+Figure I.10 illustrates the information flow between the core access-network elements for Scenario 3. Table I.6, following Figure I.10, provides further description of each message. In the example shown below, QoS is only established in the upstream direction between the CM and CMTS. A similar flow would be required in order to establish symmetric downstream QoS.
+
+![Diagram illustrating the authorization framework for Scenario 3. The diagram shows five components: Client type 3, Cable Modem (CM), Cable Modem Termination System (CMTS), Policy server, and Far end. The flow is as follows: (1) QoS request (Reserve/Commit) from Client type 3 to CMTS; (2) Policy request (w/ client credentials) from CMTS to Policy server; (3) Policy set from Policy server to CMTS; (4) Unidirectional QoS from CMTS to Far end; (5) DOCSIS service flow establishment from CMTS to Cable Modem (CM). Connections are labeled HFC between CM and CMTS, and IP between CMTS and Policy server.](8cef27a53d545bdb1676ae33150e73af_img.jpg)
+
+```
+graph LR; Client[Client type 3] -- "(1) QoS request (Reserve/Commit)" --> CMTS[Cable Modem Termination System (CMTS)]; CMTS -- "(2) Policy request (w/ client credentials)" --> Policy[Policy server]; Policy -- "(3) Policy set" --> CMTS; CMTS -.-> FarEnd[Far end]; FarEnd -.-> CMTS; CMTS -- "(5) DOCSIS service flow establishment" --> CM[Cable Modem (CM)]; CM ---|HFC| CMTS; CMTS ---|IP| Policy;
+```
+
+Diagram illustrating the authorization framework for Scenario 3. The diagram shows five components: Client type 3, Cable Modem (CM), Cable Modem Termination System (CMTS), Policy server, and Far end. The flow is as follows: (1) QoS request (Reserve/Commit) from Client type 3 to CMTS; (2) Policy request (w/ client credentials) from CMTS to Policy server; (3) Policy set from Policy server to CMTS; (4) Unidirectional QoS from CMTS to Far end; (5) DOCSIS service flow establishment from CMTS to Cable Modem (CM). Connections are labeled HFC between CM and CMTS, and IP between CMTS and Policy server.
+
+Figure I.10/J.179 – Authorization framework for Scenario 3
+
+**Table I.6/J.179 – Message details for Scenario 3**
+
+| <b>Message</b>                            | <b>Function</b>                                                          | <b>Fields</b>                                                                                     | <b>Protocol candidate</b> | <b>Comments</b>                                                                               |
+|-------------------------------------------|--------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------|---------------------------|-----------------------------------------------------------------------------------------------|
+| (1) QoS Request (Reserve/Commit)          | Client requests resource reservation from CMTS.                          | Bandwidth and Latency Parameters, Traffic Classifier, Authentication Credentials                  | RSVP                      | This scenario assumes RFC 2205 capabilities exist on the client.                              |
+| (2) Policy Request                        | CMTS solicits policy authorization decision from Policy Server.          | Bandwidth and Latency Parameters, Traffic Classifier, Authentication Credentials                  | COPS                      | RFC 2748                                                                                      |
+| (3) Policy Set                            | Policy Server installs authorization on CMTS.                            | Bandwidth and Latency Parameters, Traffic Classifier                                              | COPS                      | RFC 2748                                                                                      |
+| (4) Unidirectional QoS                    | CMTS forwards far-end RSVP signalling.                                   | Bandwidth and Latency Parameters, Traffic Classifier, Authentication Credentials                  | RSVP                      | RFC 2205                                                                                      |
+| (5) CableModem Service Flow Establishment | CMTS negotiates CableModem scheduled service flow establishment with CM. | CableModem Scheduling Type, Bandwidth and Latency Parameters, Traffic Classifier, Service Flow ID | CableModem DSx Messaging  | The QoS functions here are based on the mechanisms defined in the CableModem Recommendations. |
+
+One of the primary distinguishing characteristics of this scenario is its support for RSVP, a standard-based QoS signalling mechanism. Whereas Scenario 1 addresses Clients with no native QoS signalling capabilities, and Scenario 2 defines an IPCablecom-specific QoS signalling mechanism (based upon RSVP, but including proprietary extensions), this scenario is based on an IETF standard itself. This will provide for interoperability with standard-based Clients which have subscribed to operator QoS services and have a means of securely authenticating themselves on the access network. It also does not require applications to push policy decisions ahead of time, and hence does not impose architectural constraints on application signalling.
+
+Scenario 3 assumes that RSVP messaging is exchanged between the Client and the far end. Note however, that this does not require that all of the network elements between the Client and the far end need to support RSVP, nor does it imply the use of an integrated services (IntServ [13]) end-to-end QoS strategy. For example, differentiated services (DiffServ [16]) or another QoS scheme may be used beyond the CMTS. Also, intermediate routers that do not wish to support RSVP may simply pass the RSVP messages without processing. Alternatively, if QoS guarantees can be obtained by other means, such routers can be defined as aggregation regions and hence pass RSVP messages transparently, as defined in RFC 3175 [20].
+
+NOTE – RFC 3175 requires implementation of this aggregation function on both the near and far-end edge router.
+
+Furthermore, it should be noted that the use of RSVP in this scenario conforms closely to standard (i.e., RFC 2205) RSVP operation, and, hence, resource reservations on the access network are unidirectional. Thus, the Client reserves upstream resources, and the far-end is responsible for reserving downstream resources.
+
+Successful resource reservations are maintained similarly to reservations in the other scenarios via soft-state refreshes. RSVP clients must periodically send messages to maintain their reservations or they will timeout and be reclaimed at the CMTS.
+
+Finally, specific mechanisms are included in the RSVP protocol to allow for either the transmitting or receiving endpoint to signal the termination and tear-down of a service flow. Based on the unidirectional nature of RSVP reservations, an endpoint maintaining multiple service flows is responsible for explicitly deleting each of these flows at the conclusion of a service session.
+
+Given this model, authentication of far-end request in order to enable downstream resource reservation needs special consideration. One solution is to require that the Policy Server can authenticate both the near-end and the far-end Clients. Other solutions are possible as well, but security implications and, in particular, the potential for theft of service, must be considered carefully.
+
+### I.6.1 Example: Online gaming via native QoS signalling
+
+One potential service which may take advantage of Scenario 3 is online gaming. In this example, all that would be required is integrated, standard-based RSVP support on the Client. That is, the online game could be designed to work either with or without an Application Server.
+
+When a Client wishes to join a game, they would simply send an application-specific message to the far-end, and then proceed in requesting network QoS by sending an RSVP message, again addressed to the remote endpoint. When the CMTS receives this message, it would send a request to the Policy Server in order to authenticate the Client and decide if the QoS should be granted or not. Successful authorization would result in a unidirectional QoS reservation.
+
+Similarly, the far-end would send an RSVP message addressed to the Client. Again, when received at the CMTS, this message would be sent to the Policy Server to determine if the QoS should be granted. Upon successful authorization and servicing, the Client would then have QoS in both directions and could proceed with the online game.
+
+## I.7 Comparison of IPCablecom-T and IPCablecom multimedia
+
+This clause describes, at a high level, the main differences between the IPCablecom-T and IPCablecom Multimedia architectures. Consider that most of the specific protocol characteristics and functional details of IPCablecom Multimedia have yet to be defined as of this writing. See Table I.7, summarizing known differences for quick reference.
+
+**Table I.7/J.179 – Contrast of IPCablecom-T and IPCablecom multimedia**
+
+|                    | <b>IPCablecom-T</b>                                                                          | <b>IPCablecom multimedia</b>                                                                                                   |
+|--------------------|----------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------|
+| Services Supported | Residential Telephony<br>Basic residential telephony features<br>Extended telephony features | Multimedia Services<br>Client-based (Peer-to-Peer)<br>Server-based                                                             |
+| Event Messaging    | Robust audit trail for all policy and QoS events<br>Supports PSTN billing model              | Robust audit trail for all policy and QoS events<br>Supports QoS-based accounting<br>Supports time and volume-based accounting |
+
+**Table I.7/J.179 – Contrast of IPCablecom-T and IPCablecom multimedia**
+
+|                  | IPCablecom-T                                                                                                                                                                                                                                                                                                                       | IPCablecom multimedia                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+|------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| QoS Capabilities | <p>CableModem QoS scheduling algorithms</p> <p>Unsolicited Grant Service</p> <p>Unsolicited Grant Service with Activity Detection</p> <p>Bandwidth Characteristics</p> <p>Constant Bit Rate</p> <p>Symmetric upstream/downstream</p> <p>Level of QoS Guaranteed</p> <p>Client-to-Client (i.e., end-to-end via segmented model)</p> | <p>CableModem QoS scheduling algorithms</p> <p>Unsolicited Grant Service</p> <p>Unsolicited Grant Service with Activity Detection:</p> <ul style="list-style-type: none"> <li>• Real-Time Polling</li> <li>• Non-Real-Time Polling</li> <li>• Best-Effort with or without Priority</li> </ul> <p>Bandwidth Characteristics:</p> <ul style="list-style-type: none"> <li>• Constant bit rate</li> <li>• Variable bit rate</li> <li>• Symmetric upstream/downstream</li> <li>• Asymmetric upstream/downstream</li> </ul> <p>Level of QoS Guaranteed:</p> <ul style="list-style-type: none"> <li>• CM-CTS-to-CM (i.e., access network)</li> </ul> |
+| Security         | <p>Secure signalling and media</p> <p>Secure device provisioning and configuration management</p>                                                                                                                                                                                                                                  | <p>COPS and RADIUS secured via IPsec; key management via IKE with pre-shared key authentication (IKE with certificates or Kerberized Key Management are optional).</p> <p>Client signalling is out of the scope of this appendix, thus there is no security defined for the client signalling interface.</p>                                                                                                                                                                                                                                                                                                                                  |
+
+### I.7.1 DQoS
+
+The primary focus of IPCablecom-T is residential telephony services. As a part of this effort, the Dynamic Quality of Service (DQoS) specification was developed, defining the mechanisms necessary to deliver QoS on the CableModem-based access portion of the IP network. That is, IPCablecom-T adopts a segmented approach (dividing the end-to-end media and signalling path into near and far access networks joined by a backbone network) under which DQoS specifically addresses resource reservations on the access segment, not backbone or the end-to-end QoS.
+
+IPCablecom Multimedia is targeted toward more general multimedia applications, which transcend voice support. However, it builds on some fundamental IPCablecom-T DQoS mechanisms in order to provide QoS-enhanced services for these applications.
+
+#### I.7.1.1 Access-network elements
+
+IPCablecom-T supports the following network elements: MTA, CM, CM-CTS, CMS (logically composed of a Call Agent and Gate Controller) and RKS. In the IPCablecom Multimedia architecture, the Call Agent may functionally be mapped to an Application Manager, and the Gate Controller may functionally be mapped to the Policy Server. In the IPCablecom Multimedia architecture, additional network elements may be introduced, including, for example, a Media Server. The Application Manager and Media Server may physically reside in the same equipment, or they may be deployed separately.
+
+#### **I.7.1.2 DQoS architecture**
+
+The IPCablecom DQoS [9] architecture is based on CableModem, RSVP+, and QoS policies installed on the CMTS by the CMS (Gate Controller).
+
+As described throughout the course of this Recommendation, the IPCablecom Multimedia architecture is also based on these technologies. In addition, the multimedia effort has an objective to support a more standard-based RSVP signalling model (Scenario 3) with the intent that this capability will make QoS-enhanced services available to a larger consumer base.
+
+The CMTS in the IPCablecom-T DQoS architecture serves as the policy enforcement point for QoS policies. The CMTS will perform a similar function in the IPCablecom Multimedia architecture. In addition to servicing client-originated QoS requests, the CMTS may also receive proxied QoS requests from the Policy Server (Scenario 1). This differs from the IPCablecom-T DQoS architecture, where only the standalone MTA or the embedded MTA may initiate the activation of QoS.
+
+#### **I.7.1.3 QoS interfaces**
+
+In the IPCablecom-T architecture, signalling interfaces have been defined between all of the network elements, as well as between CMTSs for on-net to on-net calls supporting Gate Coordination. In summary, the primary signalling protocol between the MTA and the Call Agent is NCS, between the embedded MTA and the CMTS is CableModem, and between a standalone MTA and the CMTS is RSVP+. Signalling from the GC to CMTS is COPS-based Gate Control messaging.
+
+IPCablecom Multimedia builds on these signalling interfaces and additionally supports signalling interfaces between the Application Manager and the Policy Server. Recall that any application-specific signalling occurring between the Application Manager and its clients is out of the scope of this architecture.
+
+#### **I.7.1.4 Framework for IPCablecom QoS**
+
+In the IPCablecom-T QoS architecture, "a QoS defined construct called a Gate provides the control point for the connection of access networks to high quality backbone service." (See DQoS specification [14].) The Gate represents a QoS authorization that is installed on the CMTS for policy enforcement purposes. IPCablecom Multimedia defines a similar QoS policy construct, and it is anticipated that the IPCablecom-T DQoS Gate construct will be leveraged to provide the policy function in IPCablecom Multimedia. Changes to the existing IPCablecom-T Gate Control mechanisms may be required to provide attenuated QoS control (e.g., in support of Scenario 1).
+
+#### **I.7.1.5 Requirements of access-network resource management**
+
+The IPCablecom-T architecture "aims to provide a high degree of generality with the intention of enabling new services and future evolution of network architectures". The goal leads to several requirements for a viable QoS architecture in the following areas (note that each of these QoS-related capabilities is clearly defined and discussed in the IPCablecom DQoS specification):
+
+- Resource changes during a session;
+- Dynamic binding of resources;
+- Session class (priority designation);
+- Two-phase resource commitment;
+- Segmented resource assignment;
+- Backbone QoS support ;
+- Preventing theft of service.
+
+The IPCablecom Multimedia architecture will also support a single phase resource reservation model. Initially, the multimedia architecture will not address backbone QoS support, although this functionality may be formally addressed as operator needs dictate. For more information on the existing IPCablecom-T DQoS requirements please refer to the IPCablecom-T DQoS specification [14].
+
+#### **I.7.1.6 Theory of operation**
+
+IPCablecom-T DQoS involves distinct reserve and commit phases for obtaining access-network resources. At the end of the reserve phase, resources are set aside but not yet active or available to the MTA. At the end of the second phase, the resources are committed and made available for use. Under the traditional telephony model, billing begins during the commit phase.
+
+In the embedded MTA model, RSVP+ is not required between the MTA and the CMTS. Instead, the E-MTA may signal resource reservation and commitment via CableModem DSx messaging. In the standalone MTA model, RSVP+ messaging is used to perform these steps. The CM and the CMTS then coordinate via CableModem DSx messaging to schedule required service flows on the access network.
+
+As outlined in this appendix, IPCablecom Multimedia supports a model similar to IPCablecom-T, and additionally supports a more standard usage of RSVP. It also provides a proxied QoS request model, where the Application Manager manages QoS on behalf of the Client. These models are detailed in the scenarios clause of this appendix. The existing IPCablecom-T model maps to Scenario 2. The other two models are supported in the IPCablecom Multimedia architecture to provide more flexibility in the way multimedia services may be deployed in the operator's network.
+
+### **I.7.2 Event messages for billing**
+
+IPCablecom Event Messages are designed to be flexible and extensible in order to carry information about network usage for a wide variety of services delivered over the IPCablecom architecture. The IPCablecom-T Event Message specification defines the general Event Message architecture as well as the specific requirements to support IPCablecom-T voice service. The IPCablecom Event Message specification (ITU-T Rec. J.164) details a transport protocol-independent Event Message TLV format, an Event Message file format, and mandatory and optional transport protocols.
+
+These messages contain sufficient per-session information to support customer billing for service. The information contained in the Event Messages supports a wide variety of billing and settlement models. IPCablecom does not mandate the use of specific billing or settlement models as these models are defined by and based on the specific business requirements of the individual cable operator. IPCablecom neither mandates nor precludes the use of a clearinghouse for settlements.
+
+IPCablecom Event Messages are based on a model where a session or service is divided into an originating half and a terminating half. The originating CMS or MGC must generate a unique Billing Correlation ID (BCID) to identify all Event Messages associated with the originating half of the session. The terminating CMS or MGC must generate a unique BCID to identify all Event messages associated with the terminating half of the session. For each half of the session or service, the set of IPCablecom network elements that generate Event Messages (CMS, MGC, CMTS) must provide all necessary information required for billing and/or settlements as appropriate based on the service. The information generated by the originating half must be sent to the RKS supporting the originating half. The information generated by the terminating half must be sent to the RKS supporting the terminating half.
+
+A limited set of Event Messages are required for IPCablecom Multimedia services. These messages include:
+
+- Signal\_Start for "enhanced QoS service" generated by the Policy Server indicating the time at which the Policy Server receives a request for access-network QoS;
+- Signal\_Stop for "enhanced QoS service" generated by the Policy Server indicating the time at which the Policy Server receives notification that network QoS usage has terminated;
+- QoS\_Reserve, QoS\_Commit, QoS\_Stop generated by the CMTS. These messages indicate the time at which the CMTS reserves, commits or releases access-network QoS.
+
+### I.7.3 Security
+
+The IPCablecom-T security architecture defines the mechanisms, algorithms and protocols that meet security service requirements. The IPCablecom Multimedia interfaces are secured using identical mechanisms for the corresponding interfaces.
+
+# Appendix II
+
+## Guidelines for version number assignment
+
+Interoperability between different protocol versions is based on the following principles:
+
+### **Robustness Principle:**
+
+RFC 791 defines the general "robustness principle" for the Internet Protocol as follows:
+
+- "An implementation must be conservative in its sending behaviour and liberal in its receiving behaviour".
+- Following such a robustness principle, it is possible to permit minor changes in the protocol while still maintaining backwards compatibility.
+
+The general rule for protocol version numbering within PacketCable Multimedia Gate Control Protocol is as follows:
+
+- Protocol versions within the same major version number MUST be backwards compatible. Versions with different Major Version Number are not expected to be backwards compatible.
+- It is crucial that the PacketCable Multimedia Specification team examine all protocol changes to be included in a new version of the protocol and select a protocol version number based on the change with the largest impact. If any of the changes satisfy the criteria for a major protocol version change, then the major version must be incremented.
+
+Examples of protocol changes which would result in a change to the minor version number:
+
+- The introduction of a new optional object so long as the inclusion of the new object in a message does not introduce new mandatory functional requirements on the network element receiving the message such that the object could be safely ignored.
+- The deprecation of an optional object.
+
+Examples of protocol changes which would result in a change to the major version number:
+
+- The introduction of a new message.
+- A change in the format of a given object.
+- A grammar change which prohibited the inclusion of a given object in a given message.
+- A grammar change which made an object mandatory in a given message.
+- A grammar change which made an object optional in a message in which it was previously mandatory.
+- The introduction of a new optional object which when included in a message introduces new mandatory functional requirements on the network element receiving the message such that the new object could not be safely ignored.
+- A semantic change to the protocol related algorithms or states (such as the gate state machine) that could result in a state inconsistency between devices running the new and old protocol versions.
+
+Some changes, such as those which introduce new functionality, are difficult to classify. For example, one could imagine a change which introduced a new object and functional requirements on the network element receiving the object in a message. If the network element receiving the object was operating on a lower version of the protocol in which the new object was not defined, then the default behaviour would be that the object would be ignored and consequently the behaviour implied by the new object would not be performed. If the new behaviour that is not performed due to the object being ignored was local to the receiving network element, one could argue that in this case, the two network elements are successfully interoperating at the lower version of the protocol. If, on the other hand, the presence of the new object in a message required the receiving network element to send a new response or to modify an existing response based on the new object, then to ignore the new object might prevent interoperability. In the latter case, a major version change would be required.
+
+Other changes, such as those which change the status of an object within a message from mandatory to optional or vice versa, could result in interoperable implementations based on the behaviour of the sender. However, since the behaviour of a sender with respect to optional parameters cannot be guaranteed, such changes should be classified a major changes.
+
+Given that many types of protocol changes would require a major protocol version change, it makes sense to group changes to the protocol such that major version changes occur infrequently and new versions provide significant value which justifies their implementation.
+
+
+
+# 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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/J/T-REC-J.18-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg b/marked/J/T-REC-J.18-198811-I_PDF-E/2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg
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+size 7392
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@@ -0,0 +1,273 @@
+
+
+![ITU logo](2dfa6ac3edfe874f68aa0cbccaa42322_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a globe with a lightning bolt striking across it, and the letters 'ITU' superimposed on the globe.
+
+ITU logo
+
+INTERNATIONAL TELECOMMUNICATION UNION
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.180**
+
+(05/2000)
+
+SERIES J: TRANSMISSION OF TELEVISION, SOUND  
+PROGRAMME AND OTHER MULTIMEDIA SIGNALS
+
+---
+
+**User requirements for statistical multiplexing of  
+several programmes on a transmission channel**
+
+ITU-T Recommendation J.180
+
+(Formerly CCITT Recommendation)
+
+---
+
+# ITU-T J-SERIES RECOMMENDATIONS
+
+# **TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS**
+
+|                                                                                                 |             |
+|-------------------------------------------------------------------------------------------------|-------------|
+| General Recommendations                                                                         | J.1–J.9     |
+| General specifications for analogue sound-programme transmission                                | J.10–J.19   |
+| Performance characteristics of analogue sound-programme circuits                                | J.20–J.29   |
+| Equipment and lines used for analogue sound-programme circuits                                  | J.30–J.39   |
+| Digital encoders for analogue sound-programme signals                                           | J.40–J.49   |
+| Digital transmission of sound-programme signals                                                 | J.50–J.59   |
+| Circuits for analogue television transmission                                                   | J.60–J.69   |
+| Analogue television transmission over metallic lines and interconnection with radio-relay links | J.70–J.79   |
+| Digital transmission of television signals                                                      | J.80–J.89   |
+| Ancillary digital services for television transmission                                          | J.90–J.99   |
+| Operational requirements and methods for television transmission                                | J.100–J.109 |
+| Interactive systems for digital television distribution                                         | J.110–J.129 |
+| Transport of MPEG-2 signals on packetised networks                                              | J.130–J.139 |
+| Measurement of the quality of service                                                           | J.140–J.149 |
+| Digital television distribution through local subscriber networks                               | J.150–J.159 |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# **User requirements for statistical multiplexing of several programmes on a transmission channel**
+
+## **Summary**
+
+This Recommendation specifies the user requirements that should be considered for the statistical multiplexing of television and/or sound programmes as well as data programmes in order to improve the efficiency in case of utilizing a constant bit-rate digital transmission channel. It also provides a brief outline of statistical multiplexing techniques.
+
+## **Source**
+
+ITU-T Recommendation J.180 was prepared by ITU-T Study Group 9 (1997-2000) and approved under the WTSC Resolution 1 procedure on 18 May 2000.
+
+## 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 Conference (WTSC), 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 WTSC 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 Scope.....                                           | 1    |
+| 2 Informative References .....                         | 1    |
+| 3 Terms and definitions .....                          | 1    |
+| 4 Abbreviations.....                                   | 1    |
+| 5 User requirements for statistical multiplexing.....  | 1    |
+| 5.1 Functional and operational requirements.....       | 2    |
+| 5.1.1 Number of programmes.....                        | 2    |
+| 5.1.2 Range of variable bit rate.....                  | 2    |
+| 5.1.3 Compatibility .....                              | 2    |
+| 5.1.4 Interoperability.....                            | 2    |
+| 5.1.5 Flexibility.....                                 | 2    |
+| 5.1.6 Extensibility.....                               | 2    |
+| 5.1.7 Implementation .....                             | 2    |
+| 5.2 Performance requirement.....                       | 2    |
+| 5.2.1 Picture quality .....                            | 2    |
+| 5.2.2 Recovery time.....                               | 2    |
+| 5.2.3 Acquisition time .....                           | 2    |
+| 5.2.4 Relative sound/vision delay.....                 | 3    |
+| 5.2.5 Delay.....                                       | 3    |
+| 5.2.6 Error performance.....                           | 3    |
+| Appendix I – Statistical multiplexing techniques ..... | 3    |
+| I.1 Introduction.....                                  | 3    |
+| I.2 Joint coding control scheme .....                  | 3    |
+| I.3 Picture quality .....                              | 4    |
+
+# **Introduction**
+
+Statistical multiplexing is a technique that can be applied to a multiplex of television and/or sound programmes, in order that the maximum benefit may be achieved, in terms of average improvement in subjective picture and sound (and data) quality of the programmes in the multiplex, while at the same time minimizing the risk of an undue reduction of the instantaneous bit rate allocated to each programme. Such a reduction may cause the appearance of annoying instantaneous artifacts in that programme (or even in other programmes carried in the multiplex) if the bit rate required by the programme suddenly peaks as a function of its content. When introducing such techniques in digital transmission, user requirements should be established.
+
+## User requirements for statistical multiplexing of several programmes on a transmission channel
+
+# 1 Scope
+
+This Recommendation is focused on the user requirements for new multiplexing techniques that resort to statistical multiplexing in order to improve the efficiency of the utilization of a constant bit-rate digital transmission channel used to carry television and/or sound programme signals. It also provides a brief outline of statistical multiplexing techniques.
+
+These techniques measure the quasi-instantaneous bit rate requirements of each programme component in the multiplex to be transmitted, and they allocate the total bit rate available in the channel to the various components of the multiplex in a dynamic way.
+
+This approach allows to exploit the overall statistical redundancy of the information in the multiplex and its result is a benefit to all channels carried in it, since it amounts to a higher average allocation of bit rate to each multiplex component than would be possible to allocate, if each component were treated separately.
+
+# 2 Informative References
+
+- [1] ITU-T H.222.0 (2000) | ISO/IEC 13818-1:2000, *Information technology – Generic coding of moving pictures and associated audio information: Systems*.
+- [2] ITU-T H.262 (2000) | ISO/IEC 13818-2:2000, *Information technology – Generic coding of moving pictures and associated audio information: Video*.
+- [3] ITU-R draft new Recommendation [Doc.11/106], *User requirements for coding for multi-programme transmission*.
+
+# 3 Terms and definitions
+
+This Recommendation defines the following terms:
+
+- 3.1 **bouquet**: A collection of services multiplexed in a single data stream.
+- 3.2 **MPEG-2**: Refer to ISO/IEC 13818, where System is defined in [1], Video coding is defined in [2] and Audio coding is defined in 13818-3.
+
+# 4 Abbreviations
+
+This Recommendation uses the following abbreviation:
+
+MPEG      Moving Picture Experts Group
+
+# 5 User requirements for statistical multiplexing
+
+The following user requirements should govern the specification, design and testing of systems for statistical multiplexing in digital transmission.
+
+## **5.1 Functional and operational requirements**
+
+### **5.1.1 Number of programmes**
+
+The number of programmes to be multiplexed should be more than one. Maximum is not specified.
+
+### **5.1.2 Range of variable bit rate**
+
+Because a range of bit rates which can be varied would affect the size of the buffer, the coding-decoding delay and synchronisation, it should be restricted to an appropriate range to allow decoding by MPEG-2 compliant decoders.
+
+### **5.1.3 Compatibility**
+
+The techniques should allow decoding by an MPEG-2 compliant decoder. The structure of an MPEG data stream has to be taken into account in order to define an appropriate control scheme for multi-programme transmission.
+
+### **5.1.4 Interoperability**
+
+The techniques should be independent of transmission media and should allow a flexible combination of programmes inside a bouquet.
+
+### **5.1.5 Flexibility**
+
+Broadcasters or system operators should be able to reassign dynamically the configuration of services such as: the number of multiplexed programs, the target quality of each program and the picture format, as required to meet their instantaneous needs. The technique used should allow decoders to follow such changes without manual intervention by the user. The ability to provide additional data services should be retained.
+
+### **5.1.6 Extensibility**
+
+Any upgrade to the joint coding technique should be downwards compatible with existing techniques. The use of scalable transmission schemes for graceful degradation and compatible services should not be prevented by introducing the techniques.
+
+### **5.1.7 Implementation**
+
+Consideration should be given to operating a joint coding scheme when the encoders and multiplexers are at separate locations. Consideration should also be given to a re-multiplexing of primary distribution with secondary distribution in a transmission chain.
+
+## **5.2 Performance requirement**
+
+### **5.2.1 Picture quality**
+
+Overall picture quality obtained by the techniques should be superior to that obtained by conventional constant bit-rate coding. Because the resultant picture quality of a programme is affected by the complexities of other programmes in addition to its own, it is necessary to restrict the influence to an appropriate level.
+
+### **5.2.2 Recovery time**
+
+Introduction of the techniques should not increase the recovery time.
+
+### **5.2.3 Acquisition time**
+
+Introduction of the techniques should not increase the acquisition time.
+
+### **5.2.4 Relative sound/vision delay**
+
+The relative sound-video delay should be kept below the level of perceptibility.
+
+### **5.2.5 Delay**
+
+Coding delay should be close to that of a conventional coder.
+
+### **5.2.6 Error performance**
+
+Introduction of the techniques should not degrade error performance.
+
+# **APPENDIX I**
+
+## **Statistical multiplexing techniques**
+
+## **I.1 Introduction**
+
+In digital broadcasting it is highly desirable to use the available channel capacity in an effective way. In order to achieve this goal several programmes are compressed, multiplexed and transmitted over a single channel. Normally the channel capacity will be divided among these programmes in a pre-determined way, which means that each programme is allocated a fixed bit rate. Due to the fact that the bit rate required to obtain a desired picture quality depends on picture content, a constant bit rate coding leads to large variations of picture quality, and an inefficient use of the channel capacity. This suggests that a variable bit rate compression scheme that allows the channel capacity to be dynamically allocated among programmes would result in improved overall picture quality or bandwidth savings. In order to perform bit allocation across programmes, a control mechanism known as joint coding control has to be introduced. This technique is sometimes referred to as statistical multiplexing, although in conventional statistical multiplexing there is no global control mechanism.
+
+The MPEG-2 encoders available on the market today are designed to support a variable output data rate, e.g. for SDTV material in the range between 2 Mbit/s and 15 Mbit/s. In a multi-programme environment the data rates of several multiplexed programmes can be jointly controlled in such a way that the desired picture quality of each programme is achieved by using a variable bit rate encoding scheme, while maintaining the aggregate bit rate constant at the channel rate.
+
+## **I.2 Joint coding control scheme**
+
+Under the assumption that the programmes to be encoded use an MPEG-2 encoding scheme, the encoders already produce a variable output data rate that is smoothed in the output buffer of the system if a transmission over a fixed rate channel is desired. Instead of controlling the bit rate for each individual programme, a joint coding control scheme provides a variable bit rate for each programme under the assumption that the total bit rate of the system is constant and is in the optimum case the equivalent to the channel capacity. In order to control the total bit rate, the joint coding control mechanism adjusts the appropriate encoding parameters in such a way that the more complex programmes will be allocated more bits than the less complex programmes. This scheme reduces the fluctuations of the picture quality of within programmes and among the programmes transmitted in the same channel. Alternatively, the same picture quality can be achieved at a lower average bit rate per channel.
+
+This coding control scheme needs a bidirectional link between the encoders and the channel multiplexer. An example of such a control scheme is shown in Figure I.1.
+
+Another example could have the coding control in a master encoder controlling other encoders at the same location, thus avoiding a control link from the channel multiplexer to the encoders. However, this necessitates links between encoders.
+
+![Schematic for a joint coding control system showing multiple video encoders connected to a central MPEG-2 MUX.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg)
+
+The diagram illustrates a joint coding control system. On the left, multiple video inputs (Video 1, Video 2, ..., Video n) are fed into individual encoders (Encoder 1, Encoder 2, ..., Encoder n). Each encoder outputs three types of data to a central MPEG-2 MUX (incl. Coding Control): Auxiliary Data (labeled Auxiliary Data 1, Auxiliary Data 2, ..., Auxiliary Data n), main Data (labeled Data 1, Data 2, ..., Data n), and Coder Control (labeled Coder Control 1, Coder Control 2, ..., Coder Control n). The MPEG-2 MUX then outputs a single stream to the transmission channel. A vertical ellipsis between Encoder 2 and Encoder n indicates additional encoders. The identifier T0909240-00 is shown at the bottom right of the diagram.
+
+Schematic for a joint coding control system showing multiple video encoders connected to a central MPEG-2 MUX.
+
+**Figure I.1/J.180 – Schematic for a joint coding control system**
+
+## I.3 Picture quality
+
+According to some published papers, for the same average bit rate, statistical multiplexing provides an equivalent average picture quality to constant bit rate coding. However, statistical multiplexing significantly reduces the probability of lower video quality. Consequently statistical multiplexing allows a lower average bit rate per programmes to be used for the same probability of lower quality.
+
+# 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                                                                                            |
+| <b>Series J</b> | <b>Transmission of television, sound programme and other multimedia signals</b>                                                |
+| 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
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@@ -0,0 +1,885 @@
+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.185**
+
+(06/2012)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Digital transmission of television signals
+
+---
+
+**Transmission equipment for transferring  
+multi-channel television signals over optical  
+access networks by frequency modulation  
+conversion**
+
+Recommendation ITU-T J.185
+
+
+
+# **Recommendation ITU-T J.185**
+
+# **Transmission equipment for transferring multi-channel television signals over optical access networks by frequency modulation conversion**
+
+## **Summary**
+
+Recommendation ITU-T J.185 describes a transmission method for transferring multi-channel television signals over optical access networks. ITU-T J.185 transmission equipment is capable of realizing multi-channel AM-VSB, 64-QAM, and 256-QAM video signal transmission through the use of frequency modulation conversion.
+
+## **History**
+
+| Edition | Recommendation | Approval   | Study Group |
+|---------|----------------|------------|-------------|
+| 1.0     | ITU-T J.185    | 2002-02-13 | 9           |
+| 2.0     | ITU-T J.185    | 2012-06-13 | 9           |
+
+## 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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  |
+| 3.2           | Terms defined in this Recommendation.....                                                      | 2  |
+| 4             | Abbreviations and acronyms .....                                                               | 2  |
+| 5             | Conventions .....                                                                              | 3  |
+| 6             | System description.....                                                                        | 4  |
+| 7             | Performance of analogue and/or digital video transmission system .....                         | 4  |
+| 7.1           | Specified transmission quality for analogue video signal .....                                 | 4  |
+| 7.2           | Specified transmission quality for digital video signal .....                                  | 4  |
+| Annex A –     | Multi-channel video broadcast system over optical access network: system A....                 | 6  |
+| A.1           | System description.....                                                                        | 6  |
+| A.2           | TX.....                                                                                        | 8  |
+| A.3           | V-OLT .....                                                                                    | 11 |
+| A.4           | V-ONT.....                                                                                     | 12 |
+| Annex B –     | Multi-channel video broadcast system with cascaded V-OLTs: system B .....                      | 14 |
+| B.1           | System description.....                                                                        | 14 |
+| B.2           | TX.....                                                                                        | 16 |
+| B.3           | V-OLT .....                                                                                    | 19 |
+| B.4           | V-ONT.....                                                                                     | 20 |
+| Appendix I –  | FM frequency deviation and minimum received optical power for CATV band of 47 to 864 MHz.....  | 23 |
+| Appendix II – | FM frequency deviation and minimum received optical power for CATV band of 47 to 2100 MHz..... | 25 |
+|               | Bibliography.....                                                                              | 27 |
+
+
+
+# Transmission equipment for transferring multi-channel television signals over optical access networks by frequency modulation conversion
+
+# 1 Scope
+
+This Recommendation describes a method of transmitting multi-channel television signals over an optical access network that utilizes frequency modulation (FM) conversion. In this FM transmission system, multi-channel frequency-division multiplexing (FDM) television signals are simultaneously converted into one single wideband FM signal. This FM signal is then transmitted through the optical access network by using the intensity modulation technique. The video-optical network terminal (V-ONT) at the customer premises converts the received single FM signal into the original multi-channel FDM video signals, i.e., coaxial cable television (CATV) signals. The interface for this FM transmission system is the same as that of the amplitude modulation sub-carrier multiplexing (AM-SCM) system. Therefore, the FM transmission system can replace the AM-SCM system. The FM transmission system is required to have an FM converter, i.e., frequency modulator and frequency demodulator, in addition to the AM-SCM transmission system's equipment. However, it has a better efficiency than the AM-SCM transmission system against the noise deterioration caused by optical transmission/splitter loss and optical reflections.
+
+In the SCM technique, the main carrier is the optical frequency signal carrier; the sub-carriers transfer the electrically multiplexed FDM video signals in the optical sideband.
+
+This system can be added to the ITU-T G.983.1 series B-PON system by using ITU-T G.983.3 wavelength-division multiplexing (WDM) technology, to the ITU-T G.984 series G-PON system and ITU-T G.987 series XG-PON system by using ITU-T G.984.5 WDM technology, and to the IEEE 802.3ah/802.3av EPON systems. This integration would allow the system to offer broadcast services and also data and voice communication services over the same optical access network. By using the bidirectional data PON system, upstream signals, e.g., control functionality and upstream data indicating the user's requirements, can be transmitted as well.
+
+# 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 J.83] Recommendation ITU-T J.83 (2007), *Digital multi-programme systems for television, sound and data services for cable distribution*.
+- [ITU-R BO.1408-1] Recommendation ITU-R BO.1408-1 (2002), *Transmission system for advanced multimedia services provided by integrated services digital broadcasting in a broadcasting-satellite channel*.
+- [ITU-R BT.1306-3] Recommendation ITU-R BT.1306-3 (2006), *Error-correction, data framing, modulation and emission methods for digital terrestrial television broadcasting*.
+- [IEC 60728-1] IEC 60728-1 (2007), *Cable networks for television signals, sound signals and interactive services-Part 1; System performance of forward paths*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 access network** [b-ITU-T K.44]: That part of the overall telecommunication network that is located between a telecommunication centre and the customer premises building.
+
+**3.1.2 carrier** [b-ITU-R V.662-3]: An oscillation or wave, usually periodic, some characteristic of which is intended to be constrained by modulation to follow the values of a signal or of another oscillation.
+
+**3.1.3 sub-carrier multiplexing** [b-ITU-T G.982]: Multiplexing multiple electrical frequencies onto a single fibre at a single wavelength to provide an individual frequency to each multipoint-to-point path.
+
+**3.1.4 trunk network** [b-ITU-T K.44]: That part of the telecommunication system that is located between two telecommunication centres and that provides the communication between the centres.
+
+## 3.2 Terms defined in this Recommendation
+
+None.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|           |                                               |
+|-----------|-----------------------------------------------|
+| AC        | Alternating Current                           |
+| AM-SCM    | Amplitude Modulation Sub-Carrier Multiplexing |
+| AM-VSB    | Amplitude Modulation Vestigial Sideband       |
+| AMP/BRC-U | Amplifier and Branch Unit                     |
+| APD       | Avalanche Photo Diode                         |
+| BER       | Bit Error Rate                                |
+| B-PON     | Broadband Passive Optical Network             |
+| CATV      | Cable Television                              |
+| CNR       | Carrier-to-Noise Ratio                        |
+| CSO       | Composite Second Order distortion             |
+| CTB       | Composite Triple Beat distortion              |
+| DC        | Direct Current                                |
+| DI        | Discrete Interference                         |
+| D/U       | Desired-to-Undesired signal ratio             |
+| E/O       | Electrical to Optical converter               |
+| EPON      | Ethernet Passive Optical Network              |
+| FEC       | Forward Error Correction                      |
+| FDM       | Frequency-Division Multiplexing               |
+| FM        | Frequency Modulation                          |
+| G-PON     | Gigabit Passive Optical Network               |
+
+|        |                                                        |
+|--------|--------------------------------------------------------|
+| IF     | Intermediate Frequency                                 |
+| IM     | Intensity Modulated                                    |
+| ISDB-T | Integrated Services Digital Broadcasting – Terrestrial |
+| MER    | Modulation Error Rate                                  |
+| NTSC   | National Television System Committee                   |
+| OFDM   | Orthogonal Frequency Division Multiplexing             |
+| OMI    | Optical Modulation Index                               |
+| PAL    | Phase Alternating Line                                 |
+| PIN-PD | p-i-n Photo Diode                                      |
+| PON    | Passive Optical Network                                |
+| PSK    | Phase Shift Keying                                     |
+| QAM    | Quadrature Amplitude Modulation                        |
+| QPSK   | Quadrature Phase Shift Keying                          |
+| RA     | Repeater Amplifier                                     |
+| RF     | Radio Frequency                                        |
+| RIN    | Relative Intensity Noise                               |
+| RMS    | Root Mean Square                                       |
+| SBS    | Stimulated Brillouin Scattering                        |
+| SCM    | Sub-Carrier Multiplexing                               |
+| SECAM  | Séquentiel couleur à mémoire                           |
+| STB    | Set-Top Box                                            |
+| TC8PSK | Trellis-Coded Eight Phase Shift Keying                 |
+| TX     | Transmitter                                            |
+| V-OLT  | Video-Optical Line Terminal                            |
+| V-ONT  | Video-Optical Network Terminal                         |
+| VSWR   | Voltage Standing Wave Ratio                            |
+| WDM    | Wavelength-Division Multiplexing                       |
+| XG-PON | 10-Gigabit Passive Optical Network                     |
+| XM     | Cross Modulation distortion                            |
+
+# 5 Conventions
+
+In this Recommendation:
+
+The keywords "is required to" indicate a requirement which must be strictly followed and from which no deviation is permitted, if conformance to this Recommendation is to be claimed.
+
+The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely required. Thus, this requirement need not be present to claim conformance.
+
+The keywords "can optionally" indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's
+
+implementation must provide the option, and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with this Recommendation.
+
+# 6 System description
+
+Figure 1 is a system description of multi-channel television signals transmission employing frequency modulation (FM) conversion. Video signal from the headend is input to the transmitter (TX) and E/O converted, and then transmitted to the video-optical network terminal (V-ONT) via the video-optical line terminal (V-OLT). For actual installations, this system covers not only the optical access network, but also the optical trunk network with cascaded V-OLTs.
+
+![Figure 1: System configuration of an FM-converted multi-channel television signal transmission system. The diagram shows a linear sequence of four components connected by lines: Headend, TX, V-OLT, and V-ONT.](e6df2733626a85205c1db682e6259c46_img.jpg)
+
+```
+
+graph LR
+    Headend[Headend] --- TX[TX]
+    TX --- V-OLT[V-OLT]
+    V-OLT --- V-ONT[V-ONT]
+  
+```
+
+Figure 1: System configuration of an FM-converted multi-channel television signal transmission system. The diagram shows a linear sequence of four components connected by lines: Headend, TX, V-OLT, and V-ONT.
+
+**Figure 1 – System configuration of an FM-converted multi-channel television signal transmission system**
+
+# 7 Performance of analogue and/or digital video transmission system
+
+## 7.1 Specified transmission quality for analogue video signal
+
+Table 1 shows specified transmission quality for the amplitude modulation vestigial sideband (AM-VSB) analogue video signal. The carrier power of the analogue video signal is measured as the peak envelope power.
+
+**Table 1 – Specified transmission quality for analogue video signal**
+
+| TV system                      | M-system<br>NTSC        | B, G-system<br>PAL | L-system<br>SECAM |
+|--------------------------------|-------------------------|--------------------|-------------------|
+| Noise bandwidth                | 4.0 MHz                 | 4.75 MHz           | 5.0 MHz           |
+| CNR                            | $\geq 43$ dB<br>(Note)  | $\geq 44$ dB       | $\geq 44$ dB      |
+| CSO                            | $\leq -53$ dB           | $\leq -52$ dB      | $\leq -52$ dB     |
+| CTB                            | $\leq -54$ dB           | $\leq -52$ dB      | $\leq -52$ dB     |
+| XM                             | $\leq -46$ dB           | $\leq -46$ dB      | $\leq -46$ dB     |
+| DI                             | $\leq -57$ dB<br>(Note) | Not specified      | Not specified     |
+| NOTE – Refer to [IEC 60728-1]. |                         |                    |                   |
+
+## 7.2 Specified transmission quality for digital video signal
+
+Tables 2 and 3 show specified transmission quality for the digital video signal.
+
+**Table 2 – Specified transmission quality for the digital video signal**
+
+|              | 64-QAM signal                |                              |                           | 256-QAM signal               |                              |
+|--------------|------------------------------|------------------------------|---------------------------|------------------------------|------------------------------|
+|              | Annex A of [ITU-T J.83]      | Annex B of [ITU-T J.83]      | Annex A of [ITU-T J.83]   | Annex B of [ITU-T J.83]      | Annex A of [ITU-T J.83]      |
+| Symbol rate  | Not specified                | 5.057 Mbaud                  | 5.274 Mbaud               | 5.36 Mbaud                   | 5.274 Mbaud                  |
+| CNR (Note 4) | $\geq 27$ dB<br>(Notes 1, 2) | $\geq 27$ dB<br>(Notes 1, 2) | $\geq 26$ dB<br>(Note 2)  | $\geq 40$ dB<br>(Notes 1, 2) | $\geq 34$ dB<br>(Notes 1, 2) |
+| MER          | Not specified                | Not specified                | Not specified             | $\geq 32$ dB<br>(Note 1)     | Not specified                |
+| CSO/CTB      | Not specified                | Not specified                | $\leq -39$ dB<br>(Note 3) | $\leq -47$ dB<br>(Note 3)    | $\leq -45$ dB<br>(Note 3)    |
+| Pre-FEC BER  | Not specified                | $1 \times 10^{-5}$           | Not specified             | $1 \times 10^{-9}$           | Not specified                |
+| Post-FEC BER | Not specified                | $1 \times 10^{-12}$          | Not specified             | $1 \times 10^{-15}$          | Not specified                |
+
+NOTE 1 – This value includes the simultaneous presence of all impairments in the 6-MHz channel bandwidth, including composite distortion or other discrete interference.  
+NOTE 2 – The carrier power is measured as the average root mean square (RMS) signal power.  
+NOTE 3 – These undesired signals are caused by interference among AM-VSB channels.  
+NOTE 4 – Noise bandwidth is defined by symbol rate.
+
+**Table 3 – Specified transmission quality for the digital video signal**
+
+|                 | QPSK signal (Note 5)     | TC8PSK signal (Note 5)    | ISDB-T (Note 6)           |
+|-----------------|--------------------------|---------------------------|---------------------------|
+| Noise bandwidth | 28.86 MHz                | 28.86 MHz                 | 5.6 MHz                   |
+| CNR (Note 4)    | $\geq 8$ dB (Notes 1, 2) | $\geq 11$ dB (Notes 1, 2) | $\geq 24$ dB (Notes 1, 2) |
+| CSO/CTB         | Not specified            | Not specified             | $\leq -45$ dB (Note 3)    |
+
+NOTE 1 – This value includes the simultaneous presence of all impairments in the 6-MHz channel bandwidth, including composite distortion or other discrete interference.  
+NOTE 2 – The carrier power is measured as the average RMS signal power.  
+NOTE 3 – These undesired signals are caused by interference among AM-VSB channels.  
+NOTE 4 – Noise bandwidth is defined by symbol rate.  
+NOTE 5 – Refer to [ITU-R BO.1408-1].  
+NOTE 6 – Refer to [ITU-R BT.1306-3].
+
+## Annex A
+
+## Multi-channel video broadcast system over optical access network: system A
+
+(This annex forms an integral part of this Recommendation.)
+
+### A.1 System description
+
+#### A.1.1 System configuration
+
+Figure A.1 shows a block diagram of the equipment needed to transmit multi-channel television signals over optical access networks by FM conversion. This system consists of TX, V-OLT, and V-ONT. FDM multi-channel AM-VSB analogue and 64-/256-QAM digital video electrical signals output from the headend are converted into a single, electrical super-wideband FM signal by an FM converter, and then converted into an intensity modulated (IM) optical signal by the electrical/optical converter (E/O) in TX.
+
+![Block diagram of the system configuration for an FM-converted multi-channel video signal transmission system. The diagram shows a Headend connected to a TX, which is connected via an optical fiber to a V-OLT. The V-OLT contains cascaded AMP/BRC-U units, each with an Opt. Amp. and an Operation interface function. The V-OLT is connected to an Operation and management network. The V-OLT output is connected via an optical fiber to an Optical splitter, which is connected to a V-ONT. The V-ONT is connected to an STB and TV set. A legend indicates that Opt. Amp. stands for Optical Amplifier.](08441fa90c5fd11994626f662ac13f19_img.jpg)
+
+The diagram illustrates the system configuration for an FM-converted multi-channel video signal transmission system. It starts with a 'Headend' block connected to a 'TX' (Transmitter) block. An optical fiber connects the TX to a 'V-OLT' (Video Optical Line Terminal) block. Inside the V-OLT, there are two 'AMP/BRC-U' (Amplifier/Branch-Unit) blocks, labeled '#1' and '#n', indicating they are cascaded. Each AMP/BRC-U block contains an 'Opt. Amp.' (Optical Amplifier) and an 'Operation interface function' block. The V-OLT is connected to an 'Operation and management network' block via its operation interface. The output of the V-OLT is connected to an 'Optical splitter' block via an optical fiber. The output of the optical splitter is connected to a 'V-ONT' (Video Optical Network Terminal) block via an optical fiber. The V-ONT is connected to an 'STB and TV set' (Set-Top Box and Television set) block. A legend at the bottom left indicates that 'Opt. Amp.' stands for 'Optical Amplifier'. A small code 'T0914400-02' is visible near the STB and TV set block.
+
+Block diagram of the system configuration for an FM-converted multi-channel video signal transmission system. The diagram shows a Headend connected to a TX, which is connected via an optical fiber to a V-OLT. The V-OLT contains cascaded AMP/BRC-U units, each with an Opt. Amp. and an Operation interface function. The V-OLT is connected to an Operation and management network. The V-OLT output is connected via an optical fiber to an Optical splitter, which is connected to a V-ONT. The V-ONT is connected to an STB and TV set. A legend indicates that Opt. Amp. stands for Optical Amplifier.
+
+Opt. Amp. Optical Amplifier
+
+**Figure A.1 – System configuration of an FM-converted multi-channel video signal transmission system**
+
+V-OLT consists of cascaded amplifier/branch-units (AMP/BRC-U), which amplify and branch the optical signal output by the TX. The operation interface collects alarms from the whole system and transmits them to the operation and management network. AMP/BRC-U can be cascaded in several stages provided the specified relative intensity noise (RIN) degradation is not exceeded. The optical signal output by V-OLT is further branched by optical splitters and transmitted to the V-ONT in the customer's premises.
+
+The V-ONT converts the optical input signal into a single electrical super-wideband FM signal in the optical/electrical converter, and the electric signal is then demodulated into FDM multi-channel video signals by the frequency demodulator. The demodulated signal output by the V-ONT is input to the STB and the TV set.
+
+Table A.1 summarizes the functions of each device.
+
+**Table A.1 – Functions of each device**
+
+| Device                       | Functions                                                                                                                                                                                                                                                                                                                          |
+|------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| TX                           | TX converts frequency-division multiplexed AM-VSB analogue and 64-/256-QAM digital video signals into one single electrical super-wideband FM signal, and then converts this FM signal into an intensity-modulated optical signal.<br>Alarm signals are transmitted from TX to V-OLT through metallic pairs by using a data modem. |
+| AMP/BRC-U                    | AMP/BRC-U amplifies and branches input optical signal.                                                                                                                                                                                                                                                                             |
+| Operation interface function | Operation interface function collects alarms from TX and V-OLT and transfers them to the operation and management network.                                                                                                                                                                                                         |
+| V-ONT                        | V-ONT converts input optical signal to a single electrical super-wideband FM signal, and then demodulates it to frequency-division multiplexed AM-VSB analogue and 64-/256-QAM digital video signals.                                                                                                                              |
+
+#### A.1.2 Main characteristics
+
+Table A.2 shows the main characteristics of the FM-converted multi-channel video signal transmission system.
+
+**Table A.2 – Main characteristics of FM-converted multi-channel video signal transmission system**
+
+| Item and parameter                                                    | Limit                         |
+|-----------------------------------------------------------------------|-------------------------------|
+| Frequency of transmitted FDM video signals, $F_{tr}$                  | $47 \leq F_{tr} \leq 864$ MHz |
+| Relative intensity noise of the optical fibre between TX and V-OLT    | $\leq -153$ dB/Hz             |
+| Relative intensity noise of the optical fibre between V-OLT and V-ONT | $\leq -152$ dB/Hz             |
+
+NOTE – Frequency band of transmitted FDM video signals,  $47 \leq F_{tr} \leq 864$  MHz, includes regional CATV bands of 54 to 864 MHz for North America, 47 to 862 MHz for Europe, and 90 to 770 MHz for Japan.
+
+#### A.1.3 Total number of FDM carriers and their frequency deviation
+
+The total number of carriers and their FM frequency deviation is required to comply with the following formula:
+
+$$\sqrt{\sum_j^N \Delta F_j^2} \leq 0.41 \times (2500 - f_{max})$$
+
+where:
+
+$N$  Total number of FDM carriers
+
+$\Delta F_j$  FM frequency deviation of  $j$ th carrier, MHz<sub>0-p</sub>/carrier
+
+$f_{max}$  Maximum carrier frequency, MHz
+
+### A.2 TX
+
+#### A.2.1 Configuration of TX
+
+Figure A.2 provides a block diagram of a typical TX. The FM converter multiplexes the pilot signal with the FDM video signals input via the RF IN port, and then converts them to a single super-wideband FM signal with emphasis. The emphasis compensates the triangular noise generated by FM conversion. This FM signal is converted into an IM optical signal by an electrical/optical converter (E/O). The IM optical signal is input to a dispersion compensation fibre, and then amplified by an optical amplifier. The amplified optical signal from OPT OUT is transmitted to the V-OLT. The dispersion compensation fibre compensates the chromatic dispersion of the primary transmission fibre from TX to V-OLT.
+
+![Block diagram of the TX configuration showing signal flow from RF IN through FM converter, Electrical/optical converter, Dispersion compensation fiber, and Optical amplifier to OPT OUT. It also shows monitoring points RF MON and FM MON, a Pilot signal generator, an Alarm administration function, and a DC power supplier connected to AC IN.](a33da0f14e456f92539ce3e9b7d81f9a_img.jpg)
+
+The diagram illustrates the internal configuration of a transmitter (TX). The main signal path starts at the **RF IN** port, which splits: one branch goes to the **RF MON** (Radio Frequency Monitor) port, and the other enters the **FM converter**. The **FM converter** also receives input from a **Pilot signal generator**. The output of the FM converter is connected to the **Electrical/optical converter**, which outputs to the **FM MON** (Frequency Modulation Monitor) port. The signal then passes through a **Dispersion compensation fiber** and an **Optical amplifier** to the **OPT OUT** (Optical Output) port. Below the main signal path, a **Pilot signal generator** is connected to an **Alarm administration function**. This function also receives inputs from the **Electrical/optical converter** and the **Dispersion compensation fiber**. The **Alarm administration function** outputs to the **ALM OUT** (Alarm Output) port. A **DC power supplier** is connected to the **AC IN** (AC Input) port and provides power to the **Alarm administration function** and the **Optical amplifier**. The reference code T0914410-02 is shown in the bottom right corner.
+
+Block diagram of the TX configuration showing signal flow from RF IN through FM converter, Electrical/optical converter, Dispersion compensation fiber, and Optical amplifier to OPT OUT. It also shows monitoring points RF MON and FM MON, a Pilot signal generator, an Alarm administration function, and a DC power supplier connected to AC IN.
+
+**Figure A.2 – Configuration of TX**
+
+The pilot signal is used in order to confirm that signal transmission was normal. It is possible to modulate the pilot signal with angular modulation if necessary.
+
+The RF MON port is the RF signal monitor port used for measuring the input RF signal quality and its level during system operation.
+
+The input RF signal is divided with the appropriate splitting ratio in order to output the RF monitor signal from the RF MON port. The ratio is small so that the splitting does not degrade the main RF signal.
+
+The alarm administration function collects the alarms generated by each function. When an alarm is collected, it is transferred from ALM OUT to the operation interface function of the V-OLT.
+
+#### A.2.2 Main characteristics of TX
+
+Main characteristics of TX are shown in Table A.3. Figure A.3 shows how to measure the electrical phase noise level. Electrical phase noise is measured at the frequency of  $f_{meas}$  MHz far from IF when video modulation is not applied.
+
+**Table A.3 – Main characteristics of TX**
+
+| Item and parameter                                              |                               | Limit                                                                                                          | Meaning and condition                                                                                     |
+|-----------------------------------------------------------------|-------------------------------|----------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------|
+| Electrical input signal                                         | Reference level               | 85 dB $\mu$ V/carrier                                                                                          | Carrier level of AM-VSB signal.                                                                           |
+|                                                                 | Impedance of RF IN port       | 75 $\Omega$ unbalanced                                                                                         |                                                                                                           |
+| FM frequency deviation                                          |                               | $70.0 \times 10^{\frac{12.9-(f-47)}{16340}} \times 10^{\frac{V_{in}-85\pm 1}{20}}$ MHz <sub>0-p</sub> /carrier | When carrier frequency is $f$ MHz, and signal input level is $V_{in}$ dB $\mu$ V/ch.                      |
+| Emphasis level difference for triangular noise of FM modulation |                               | $12.9 \pm 1.0$ dB                                                                                              | For input RF frequencies from 47 MHz to 864 MHz.                                                          |
+| Output optical signal                                           | Optical spectrum              | Single longitudinal mode                                                                                       |                                                                                                           |
+|                                                                 | Wavelength                    | $1555 \pm 5$ nm                                                                                                |                                                                                                           |
+|                                                                 | Output power                  | $\geq +12$ dBm                                                                                                 |                                                                                                           |
+| Output optical signal                                           | Optical modulation index, OMI | $70 \leq \text{OMI} \leq 95\%$                                                                                 |                                                                                                           |
+|                                                                 | Relative intensity noise, RIN | $\leq -140$ dB/Hz                                                                                              | RIN of optical output signal from TX.                                                                     |
+| Electrical phase noise                                          |                               | $\leq 10 \log_{10} \left( \frac{50 \times 10^{-9}}{2\pi f_{meas}} \right)^2$ dB/Hz                             | See Figure A.3.                                                                                           |
+| Harmonic distortion                                             | Second-order                  | $\leq -27$ dBc                                                                                                 | Electrical level comparison against $J_0$ component at IF frequency when video modulation is not applied. |
+|                                                                 | Third-order                   | $\leq -19$ dBc                                                                                                 |                                                                                                           |
+| FM carrier frequency, IF                                        |                               | $3.0 \pm 0.50$ GHz                                                                                             |                                                                                                           |
+| Drift range of IF frequency                                     |                               | $\leq 0.15$ GHz                                                                                                | Drift for 5 minutes.                                                                                      |
+| Suppression level of residual AM components                     |                               | $\geq 50$ dB                                                                                                   | See Figure A.4.                                                                                           |
+| Pilot signal                                                    | Frequency accuracy            | $\leq 50$ ppm                                                                                                  | Video modulation not applied.                                                                             |
+|                                                                 | Amplitude                     | $82 \pm 0.5$ dB $\mu$ V                                                                                        | Converted value as a signal input level from the "RF IN" port.                                            |
+
+![Figure A.3: TX output spectrum when no video modulation is applied. The graph shows a sharp peak at the Intermediate Frequency (IF) labeled 'J0 component of FM signal'. The peak height is C0. At a frequency offset fmeas MHz from the IF, the noise level is Nph. The phase noise level is defined as Nph/C0. The x-axis is labeled 'Frequency' and has a reference code T0914420-02.](ad29805cd4f64ad2828e14feb66de664_img.jpg)
+
+Figure A.3 shows the TX output spectrum when no video modulation is applied. The graph displays a sharp peak at the Intermediate Frequency (IF) labeled  $J_0$  component of FM signal. The peak height is  $C_0$ . At a frequency offset  $f_{meas}$  MHz from the IF, the noise level is  $N_{ph}$ . The phase noise level is defined as  $N_{ph}/C_0$ . The x-axis is labeled Frequency and has a reference code T0914420-02.
+
+Figure A.3: TX output spectrum when no video modulation is applied. The graph shows a sharp peak at the Intermediate Frequency (IF) labeled 'J0 component of FM signal'. The peak height is C0. At a frequency offset fmeas MHz from the IF, the noise level is Nph. The phase noise level is defined as Nph/C0. The x-axis is labeled 'Frequency' and has a reference code T0914420-02.
+
+TX output spectrum when no video modulation is applied.
+
+**Figure A.3 – Definition of electrical phase noise level**
+
+![Figure A.4: Definition of suppression level of residual AM component. The graph compares two spectra: 'Spectrum without video modulation' (a dashed line with a sharp peak C0) and 'With video modulation' (a solid line with a broader peak). The suppression level of the residual AM component is defined as C0/CrAM, where CrAM is the amplitude of the residual AM component at the IF. The x-axis is labeled 'Frequency' and has a reference code T0914430-02.](cbc4516eb885829fe8c9dabc0946dcbe_img.jpg)
+
+Figure A.4 shows the definition of suppression level of residual AM component. The graph compares two spectra: Spectrum without video modulation (dashed line) and With video modulation (solid line). The suppression level of residual AM component is defined as  $C_0/C_{rAM}$ , where  $C_{rAM}$  is the amplitude of the residual AM component at the IF. The x-axis is labeled Frequency and has a reference code T0914430-02.
+
+Figure A.4: Definition of suppression level of residual AM component. The graph compares two spectra: 'Spectrum without video modulation' (a dashed line with a sharp peak C0) and 'With video modulation' (a solid line with a broader peak). The suppression level of the residual AM component is defined as C0/CrAM, where CrAM is the amplitude of the residual AM component at the IF. The x-axis is labeled 'Frequency' and has a reference code T0914430-02.
+
+**Figure A.4 – Definition of suppression level of residual AM component**
+
+#### A.2.3 Alarm administration items of TX
+
+Alarm administration items that are recommended to be observed by the TX are shown in Table A.4.
+
+**Table A.4 – Alarm administration items of TX**
+
+| Alarm administration item             | Symbol  | Alarm occurrence condition                                                                     |
+|---------------------------------------|---------|------------------------------------------------------------------------------------------------|
+| Video transmission signal input alarm | REC     | When input signal level is less than that of a single carrier.                                 |
+| MOD output alarm                      | MOD OUT | When FM converter output signal is abnormal.                                                   |
+| E/O output alarm                      | E/O OUT | When optical output power level is abnormal.                                                   |
+| Optical amplifier alarm               | AMP OUT | When pump light power level is abnormal.<br>When optical input/output power level is abnormal. |
+| Power supply alarm                    | PWR ALM | When an error is found at the power supply.                                                    |
+| AC power input interruption           | AC DWN  | When an error is found in AC power input.                                                      |
+| Fan alarm                             | FAN     | When an error is found in FAN.                                                                 |
+
+### A.3 V-OLT
+
+#### A.3.1 Main characteristics of V-OLT
+
+Table A.5 shows the main characteristics of V-OLT.
+
+**Table A.5 – Main characteristics of V-OLT**
+
+|                   | Item and parameter                                | Limits              | Meaning and condition                                                                |
+|-------------------|---------------------------------------------------|---------------------|--------------------------------------------------------------------------------------|
+| Optical amplifier | Input/output optical signal wavelength, $\lambda$ | $1555 \pm 5$ nm     |                                                                                      |
+|                   | Output power                                      | $\geq +14$ dBm      |                                                                                      |
+|                   | Relative intensity noise, RIN                     | $\leq -137.7$ dB/Hz | Input power is $-8$ dBm.<br>Includes RIN degradation caused by opening of connector. |
+|                   | The number of AMP accommodated in the V-OLT       | Not specified       |                                                                                      |
+|                   | The number of output ports                        | Not specified       |                                                                                      |
+
+#### A.3.2 Alarm administration items
+
+Alarm administration items of V-OLT are shown in Table A.6.
+
+**Table A.6 – Alarm administration items of V-OLT**
+
+| Name of the function       | Alarm administration item       | Symbol  | Alarm occurrence conditions                                                              |
+|----------------------------|---------------------------------|---------|------------------------------------------------------------------------------------------|
+| Optical amplifier function | Optical input alarm             | REC     | When optical input power level is abnormal.                                              |
+|                            | Optical output alarm            | OUT     | When pump light power level is abnormal.<br>When optical output power level is abnormal. |
+|                            | Power supply alarm              | PWR ALM | When an error is found in the power supply.                                              |
+| TX monitor function        | Pilot alarm                     | PIL     | When the power level of pilot signal that is transmitted from TX is abnormal.            |
+|                            | Alarm administration line alarm | MODEM   | When alarm administration line between TX and V-OLT is interrupted.                      |
+|                            | Power supply alarm              | PWR ALM | When an error is found in the power supply.                                              |
+| Common                     | FUSE alarm                      | FUSE    | When fuse of equipment is out.                                                           |
+
+### A.4 V-ONT
+
+#### A.4.1 Configuration of V-ONT
+
+Figure A.5 shows a block diagram of V-ONT. The optical signal output by V-OLT is converted into a single electrical super-wideband FM signal by the optical/electrical converter, and then converted into the original FDM video signals by the FM demodulator. The demodulated signal is output after it is amplified to the appropriate level by the electrical amplifier.
+
+![Block diagram of V-ONT configuration showing signal flow from OPT IN through Optical/electrical converter, FM demodulator, and Electrical amplifier to RF OUT. Power source, G, and ALM output are also shown.](4356776ca004ecba5d599667a155d7d4_img.jpg)
+
+The diagram illustrates the internal configuration of a V-ONT. On the left, an 'OPT IN' terminal connects to an 'Optical/electrical converter' block. This block is connected to an 'FM demodulator' block, which in turn connects to an 'Electrical amplifier' block. The output of the electrical amplifier is connected to an 'RF OUT' terminal on the right. Below the main signal path, a 'Power supplier' block is connected to a 'Power source' terminal. A common ground line, labeled 'G', connects the 'Power source', the 'Electrical amplifier', and an 'Alarm administration function' block. The 'Alarm administration function' block is also connected to an 'ALM output' terminal. The entire system is enclosed in a rectangular frame. A small label 'T0914440-02' is located at the bottom right of the diagram.
+
+Block diagram of V-ONT configuration showing signal flow from OPT IN through Optical/electrical converter, FM demodulator, and Electrical amplifier to RF OUT. Power source, G, and ALM output are also shown.
+
+Figure A.5 – Configuration of V-ONT
+
+Pilot signal level is observed by the alarm administration function. An alarm is output when the pilot signal level does not meet the specified value. This alarm indicates whether there is transmission signal error or not.
+
+#### A.4.2 Main characteristics of V-ONT
+
+Table A.7 shows the main characteristics of V-ONT.
+
+Table A.7 – Main characteristics of V-ONT
+
+| Item and parameter |                       | Limit and specification | Meaning and condition                                   |
+|--------------------|-----------------------|-------------------------|---------------------------------------------------------|
+| Optical input      | Minimum input power   | $\leq -15$ dBm          |                                                         |
+|                    | Wavelength, $\lambda$ | $1555 \pm 5$ nm         |                                                         |
+| Electrical output  | Power level           | $\geq 75$ dB $\mu$ V    | When signal input level of TX is 85 dB $\mu$ V/carrier. |
+|                    | VSWR                  | $\leq 2.5$              |                                                         |
+|                    | Impedance             | 75 $\Omega$ unbalanced  |                                                         |
+
+#### A.4.3 Alarm administration items of V-ONT
+
+Table A.8 lists the alarm item of V-ONT.
+
+**Table A.8 – Alarm administration item of V-ONT**
+
+| <b>Alarm administration item</b> | <b>Symbol</b> | <b>Alarm occurrence conditions</b>                                     | <b>Remark</b>                            |
+|----------------------------------|---------------|------------------------------------------------------------------------|------------------------------------------|
+| Output alarm                     | OUT           | When the power level of pilot signal is lower than the specified value | Pilot signal is measured at RF OUT port. |
+
+## Annex B
+
+## Multi-channel video broadcast system with cascaded V-OLTs: system B
+
+(This annex forms an integral part of this Recommendation.)
+
+### B.1 System description
+
+#### B.1.1 System configuration
+
+Figure B.1 shows a block diagram of the equipment needed to transmit multi-channel video signals over optical trunk and access networks by FM conversion. This system consists of TX, V-OLT, and V-ONT. Frequency-division multiplexing (FDM) multi-channel AM-VSB analogue and 64-/256-QAM, OFDM, PSK, and TC8PSK digital video electrical signals output from the headend are converted into a single, electrical super-wideband FM signal by an FM converter, and then converted into an intensity modulated (IM) optical signal by the electrical/optical converter (E/O) in TX.
+
+![Block diagram of the system configuration for an FM-converted multi-channel video signal transmission system. The diagram shows a sequence of components: Head-end, TX, Optical trunk network, V-OLT, Optical trunk network, V-OLT, and Optical trunk network (indicated by a dashed line). Each V-OLT is connected to an Optical access network, which in turn connects to a V-ONT. The V-ONTs are shown with ellipses indicating multiple units.](2eb23c2210154279f8013a1594fbcc5a_img.jpg)
+
+```
+graph LR; Headend[Head-end] --> TX[TX]; TX --> OTN1(Optical trunk network); OTN1 --> VOLT1[V-OLT]; VOLT1 --> OTN2(Optical trunk network); VOLT1 --> OAN1(Optical access network); OAN1 --> VONT1[V-ONT]; OTN2 --> VOLT2[V-OLT]; VOLT2 --> OTN3(Optical trunk network); VOLT2 --> OAN2(Optical access network); OAN2 --> VONT2[V-ONT];
+```
+
+Block diagram of the system configuration for an FM-converted multi-channel video signal transmission system. The diagram shows a sequence of components: Head-end, TX, Optical trunk network, V-OLT, Optical trunk network, V-OLT, and Optical trunk network (indicated by a dashed line). Each V-OLT is connected to an Optical access network, which in turn connects to a V-ONT. The V-ONTs are shown with ellipses indicating multiple units.
+
+J.185(12)\_FB.1
+
+**Figure B.1 – System configuration of an FM-converted multi-channel video signal transmission system**
+
+V-OLT consists of a repeater amplifier unit (RA-U) and amplifier/branch-units (AMP/BRC-U). The RA amplifies the optical signal from the TX and launches its optical output to the trunk network to the next V-OLT or to the AMP/BRC-U. The operation interface collects alarms from the whole system and transmits them to the operation and management network. AMP/BRC-U can be cascaded in several stages provided the specified RIN degradation is not exceeded. The optical signal output from V-OLT is further branched by optical splitters and transmitted to the V-ONT in the customer's premises.
+
+The V-ONT converts the optical input signal into a single electrical super-wideband FM signal in the optical/electrical converter, and the electric signal is then demodulated into FDM multi-channel video signals by the frequency demodulator. The demodulated signal output by the V-ONT is input to the STB and the TV set.
+
+Table B.1 summarizes the functions of each device.
+
+**Table B.1 – Functions of each device**
+
+| Device | Functions                                                                                                                                                                                                                                                                                                              |
+|--------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| TX     | TX converts frequency-division multiplexed AM-VSB analogue and digital video signals into one single electrical super-wideband FM signal, and then converts this FM signal into an intensity-modulated optical signal.<br>Alarm signals are transmitted from TX to V-OLT through metallic pairs by using a data modem. |
+| V-OLT  | The V-OLT amplifies the optical input signal from the TX or the precedent V-OLT and launches the optical output power to the following optical trunk network or the optical access network.                                                                                                                            |
+| V-ONT  | V-ONT converts input optical signal to a single electrical super-wideband FM signal, and then demodulates it to frequency-division multiplexed AM-VSB analogue and digital video signals.                                                                                                                              |
+
+#### B.1.2 Main characteristics
+
+Table B.2 shows the main characteristics of the FM-converted multi-channel video signal transmission system.
+
+**Table B.2 – Main characteristics of FM-converted multi-channel video signal transmission system**
+
+| Item and parameter                                                          | Limit                                                             |
+|-----------------------------------------------------------------------------|-------------------------------------------------------------------|
+| Frequency of transmitted FDM video signals, $F_{tr}$                        | $47 \leq F_{tr} \leq 864$ MHz<br>$1000 \leq F_{tr} \leq 2150$ MHz |
+| Relative intensity noise due to optical fibre transmission from TX to V-ONT | $\leq -136$ dB/Hz                                                 |
+
+NOTE – Frequency band of transmitted FDM video signals,  $47 \leq F_{tr} \leq 2150$  MHz, includes regional CATV bands of 54 to 864 MHz for North America, 47 to 862 MHz for Europe, and 90 to 770 MHz and 1000 to 2150 MHz for Japan.
+
+#### B.1.3 Total number of FDM carriers and their frequency deviation
+
+The total number of carriers and their FM frequency deviation is required to comply with the following formula:
+
+$$\sqrt{\sum_j^N \Delta F_j^2} \leq 700$$
+
+where:
+
+$N$  Total number of FDM carriers
+
+$\Delta F_j$  FM frequency deviation of  $j$ th carrier, MHz<sub>0-p</sub>/carrier
+
+### B.2 TX
+
+#### B.2.1 Configuration of TX
+
+Figure B.2 provides a block diagram of a typical TX. The FM converter multiplexes the optional pilot signal with the FDM video signals input via one or more RF IN ports, and then converts them to a single super-wideband FM signal with emphasis. The emphasis compensates the triangular noise generated by FM conversion. This FM signal is converted into an IM optical signal by an electrical/optical converter (E/O). The IM optical signal is input to an optional dispersion compensation fibre and then amplified by an optional optical amplifier, if necessary. The amplified optical signal from OPT OUT is transmitted to the V-OLT. The dispersion compensation fibre compensates the chromatic dispersion of the primary transmission fibre from TX to V-OLT.
+
+![Block diagram of the TX configuration showing signal flow from RF inputs through an FM converter, E/O converter, dispersion compensation fibre, and optical amplifier to the OPT OUT. It also shows a pilot signal generator, alarm administration function, and power supply connections.](e180f2b5fcbe8001554a7c0677cd3f82_img.jpg)
+
+The diagram illustrates the internal configuration of a Transmitter (TX). On the left, two RF input ports are shown: 'RF IN (PSK-FDM)' and 'RF IN (analogue and QAM-FDM)'. Both inputs feed into an 'FM converter' block. An 'optional pilot signal generator' also feeds into the 'FM converter'. The output of the 'FM converter' goes to an 'Electrical/optical converter' block. This block's output goes to a 'Dispersion compensation fibre (optional)' block, which in turn connects to an 'Optical amplifier (optional)' block. The final output is 'OPT OUT'. Below the main signal path, an 'Alarm administration function' block receives status inputs from the 'FM converter', 'Electrical/optical converter', 'Dispersion compensation fibre (optional)', and 'Optical amplifier (optional)'. This block has an 'ALM OUT' terminal at the bottom. A 'DC power supply' block is connected to the 'Alarm administration function' and has an 'AC IN' terminal at the bottom. The diagram is labeled 'J.185(12)\_B.2' in the bottom right corner.
+
+Block diagram of the TX configuration showing signal flow from RF inputs through an FM converter, E/O converter, dispersion compensation fibre, and optical amplifier to the OPT OUT. It also shows a pilot signal generator, alarm administration function, and power supply connections.
+
+**Figure B.2 – Configuration of TX**
+
+The pilot signal is used in order to confirm that signal transmission to V-OLT and V-ONT was normal. It is possible to modulate the pilot signal with angular modulation if necessary. Alternatively, total RF power can be used for these purposes, thereby eliminating the need for a pilot signal.
+
+A variety of signal monitoring ports is optionally provided, including the RF input signal, the FM converted signal, and the optical output signal for measuring the signal quality during system operation.
+
+The alarm administration function collects the alarms generated by each function. When an alarm is collected, it is transferred from ALM OUT to the operation interface function of the V-OLT.
+
+#### B.2.2 Main characteristics of TX
+
+Main characteristics of TX are shown in Table B.3. Figure B.3 shows how to measure the electrical phase noise level. Electrical phase noise is measured at the frequency offset of  $f_{meas}$  MHz from IF when video modulation is not applied.
+
+**Table B.3 – Main characteristics of TX**
+
+| Item and parameter                                              |                               | Limit                                                                                     | Meaning and condition                                                                                     |
+|-----------------------------------------------------------------|-------------------------------|-------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------|
+| Electrical input signal                                         | Reference level               | Not specified                                                                             |                                                                                                           |
+|                                                                 | Impedance of RF IN port       | 75 Ω unbalanced                                                                           |                                                                                                           |
+| Total deviation of RF carriers                                  |                               | 700 MHz                                                                                   |                                                                                                           |
+| Emphasis level difference for triangular noise of FM modulation |                               | $12.9 \pm 1.0$ dB                                                                         | For input RF frequencies from 47 MHz to 864 MHz.                                                          |
+|                                                                 |                               | $8.4 \pm 1.0$ dB                                                                          | For input RF frequencies from 1000 to 2150 MHz.                                                           |
+| Output optical signal                                           | Optical spectrum              | Single longitudinal mode                                                                  |                                                                                                           |
+|                                                                 | Wavelength                    | $1555 \pm 5$ nm                                                                           |                                                                                                           |
+|                                                                 | Output power                  | $\geq +0$ dBm                                                                             | When optical amplifier is not used.                                                                       |
+|                                                                 | Optical modulation index, OMI | $70 \leq \text{OMI} \leq 95\%$                                                            |                                                                                                           |
+|                                                                 | Relative intensity noise, RIN | $\leq -140$ dB/Hz                                                                         | RIN of optical output signal from TX.                                                                     |
+|                                                                 | SBS tolerance                 | +12 dBm                                                                                   | Launch into 65 km ITU-T G.652 fibre.                                                                      |
+| Electrical phase noise                                          |                               | $\leq 10 \log_{10} \left( \frac{50 \times 10^{-9}}{2\pi f_{\text{meas}}^2} \right)$ dB/Hz | See Figure B.3.                                                                                           |
+| Harmonic distortion                                             | Second-order                  | $\leq -27$ dBc                                                                            | Electrical level comparison against $J_0$ component at IF frequency when video modulation is not applied. |
+|                                                                 | Third-order                   | $\leq -19$ dBc                                                                            |                                                                                                           |
+| FM carrier frequency, IF                                        |                               | $3.0 \pm 0.50$ GHz                                                                        |                                                                                                           |
+| Drift range of IF frequency                                     |                               | $\leq 0.15$ GHz                                                                           | Drift for 5 minutes.                                                                                      |
+| Suppression level of residual AM components                     |                               | $\geq 50$ dB                                                                              | See Figure B.4.                                                                                           |
+
+![Figure B.3: TX output spectrum when no video modulation is applied. The graph shows a sharp peak labeled 'J₀ component of FM signal' with a height of C₀. At a frequency offset f_meas MHz from the center IF, the noise level is N_ph. The phase noise level is defined as N_ph/C₀. The x-axis is labeled 'Frequency' and has a reference code T0914420-02.](9ce50bc10864dc86e1cdee4be08f1897_img.jpg)
+
+Figure B.3: TX output spectrum when no video modulation is applied. The graph shows a sharp peak labeled 'J₀ component of FM signal' with a height of C₀. At a frequency offset f\_meas MHz from the center IF, the noise level is N\_ph. The phase noise level is defined as N\_ph/C₀. The x-axis is labeled 'Frequency' and has a reference code T0914420-02.
+
+TX output spectrum when no video modulation is applied.
+
+**Figure B.3 – Definition of electrical phase noise level**
+
+![Figure B.4: Definition of suppression level of residual AM component. The graph compares two spectra: 'Spectrum without video modulation' (a dashed line with a sharp peak C₀) and 'With video modulation' (a solid line with a broader peak). The suppression level of the residual AM component is defined as C₀/C_rAM, where C_rAM is the amplitude of the residual AM component at the IF. The x-axis is labeled 'Frequency' and has a reference code T0914430-02.](45329c7d9aa2bd1290af5b2027f08d7e_img.jpg)
+
+Figure B.4: Definition of suppression level of residual AM component. The graph compares two spectra: 'Spectrum without video modulation' (a dashed line with a sharp peak C₀) and 'With video modulation' (a solid line with a broader peak). The suppression level of the residual AM component is defined as C₀/C\_rAM, where C\_rAM is the amplitude of the residual AM component at the IF. The x-axis is labeled 'Frequency' and has a reference code T0914430-02.
+
+**Figure B.4 – Definition of suppression level of residual AM component**
+
+#### B.2.3 Alarm administration items of TX
+
+Alarm administration items that are recommended to be observed by the TX are shown in Table B.4.
+
+**Table B.4 – Alarm administration items of TX**
+
+| Alarm administration item             | Symbol  | Alarm occurrence condition                                     |
+|---------------------------------------|---------|----------------------------------------------------------------|
+| Video transmission signal input alarm | REC     | When input signal level is less than that of a single carrier. |
+| MOD output alarm                      | MOD OUT | When FM converter output signal is abnormal.                   |
+| E/O output alarm                      | E/O OUT | When optical output power level is abnormal.                   |
+| Power supply alarm                    | PWR ALM | When an error is found in the power supply.                    |
+
+### B.3 V-OLT
+
+#### B.3.1 Configuration of V-OLT
+
+Figure B.5 shows a block diagram of the V-OLT. The optical input signal to the V-OLT travels through optional dispersion compensation fibre (DCF) which compensates the optical chromatic dispersion of the trunk network before the V-OLT. The optical signal is then amplified by an optical repeater amplifier (RA). One or more of the RA output ports are followed by the optical trunk network to the next V-OLTs, and other output ports by cascaded distribution amplifiers and branches (AMP/BRCs). The optical output signal from the AMP/BRC is launched into the optical access network. Note that the detailed arrangement of the V-OLT is variable. For example, when a V-OLT does not accommodate optical access networks and is used only to extend the optical trunk network, the AMP/BRC can be removed. When the system does not cover the optical trunk network, the RA can be removed.
+
+The alarm administration function collects the alarms generated by each function and transfers them to the operation interface.
+
+![Block diagram of V-OLT configuration showing signal flow from input to next stage V-OLT and access line, with power supply and alarm administration components.](2734e7f9be3e1dc046f14be2e6c9a085_img.jpg)
+
+The diagram illustrates the internal configuration of a V-OLT. An optical input signal enters from the left, labeled 'From TX or previous stage V-OLT'. This signal passes through a 'Dispersion compensation fibre (optional)' block. The output of this block then splits: one path goes to a 'Repeater amplifier (RA)' block, and the other goes to an 'Alarm administration function' block. The 'Repeater amplifier (RA)' has multiple output ports on the right. The top output is labeled 'To next stage V-OLT', and the bottom output is labeled 'To access line'. Below the 'Repeater amplifier (RA)' is a 'Distribution amplifiers and branches (AMP/BRC)' block, which also has multiple output ports on the right, labeled 'To access line'. A 'DC power supply' block is connected to the 'Alarm administration function' block. The 'DC power supply' has an 'AC IN' input at the bottom left. The 'Alarm administration function' has an 'ALM OUT' output at the bottom center. The entire V-OLT unit is enclosed in a rectangular box labeled 'V-OLT' at the top left. The diagram is labeled 'J.185(12)\_B.5' at the bottom right.
+
+Block diagram of V-OLT configuration showing signal flow from input to next stage V-OLT and access line, with power supply and alarm administration components.
+
+**Figure B.5 – Configuration of V-OLT**
+
+#### B.3.2 Main characteristics of V-OLT
+
+Table B.5 shows the main characteristics of V-OLT.
+
+**Table B.5 – Main characteristics of V-OLT**
+
+|         | Item and parameter                                | Limits                  | Meaning and condition                                                                |
+|---------|---------------------------------------------------|-------------------------|--------------------------------------------------------------------------------------|
+| RA      | Input/output optical signal wavelength, $\lambda$ | $1555 \pm 5$ nm         |                                                                                      |
+|         | Input power                                       | $\geq -8$ dBm           |                                                                                      |
+|         | Output power                                      | MAX +21.3 dBm<br>(Note) |                                                                                      |
+|         | Noise figure                                      | $\leq 6$ dB             | Input power is $-8$ dBm.                                                             |
+|         | Relative intensity noise, RIN                     | $\leq -141$ dB/Hz       | Input power is $-8$ dBm.<br>Includes RIN degradation caused by opening of connector. |
+|         | The number of output ports                        | Not specified           |                                                                                      |
+| AMP/BRC | Input/output optical signal wavelength, $\lambda$ | $1555 \pm 5$ nm         |                                                                                      |
+|         | Input power                                       | $\geq +5$ dBm           |                                                                                      |
+|         | Output power                                      | MAX +21.3 dBm<br>(Note) |                                                                                      |
+|         | Noise figure                                      | $\leq 13$ dB            | Input power is $+5$ dBm.                                                             |
+|         | Relative intensity noise, RIN                     | $\leq -148$ dB/Hz       | Input power is $+5$ dBm.                                                             |
+|         | The number of output ports                        | Not specified           |                                                                                      |
+
+NOTE – Output power of trunk network and access network is less than SBS suppression level.
+
+#### B.3.3 Alarm administration items
+
+Alarm administration items of V-OLT are shown in Table B.6.
+
+**Table B.6 – Alarm administration items of V-OLT**
+
+| Name of the function       | Alarm administration item | Symbol  | Alarm occurrence conditions                                                              |
+|----------------------------|---------------------------|---------|------------------------------------------------------------------------------------------|
+| Optical amplifier function | Optical input alarm       | REC     | When optical input power level is abnormal.                                              |
+|                            | Optical output alarm      | OUT     | When pump light power level is abnormal.<br>When optical output power level is abnormal. |
+|                            | Power supply alarm        | PWR ALM | When an error is found in the power supply.                                              |
+
+### B.4 V-ONT
+
+#### B.4.1 Configuration of V-ONT
+
+Figure B.6 shows a block diagram of V-ONT. The optical signal output from V-OLT is converted into a single electrical super-wideband FM signal by the optical/electrical converter, and then converted into the original FDM video signals by the FM demodulator. The demodulated signal is
+
+output after it is amplified to the appropriate level by the electrical amplifier. Note that in many applications, the V-ONT is integrated into the digital ONT, even to the extent that the optics of both units are integrated into a single 'triplelexer'.
+
+![Figure B.6 – Configuration of V-ONT. The diagram shows a block diagram of the V-ONT. On the left, 'OPT IN' connects to an 'Optical/electrical converter'. This converter is connected to an 'FM demodulator', which is connected to an 'Electrical amplifier'. The 'Electrical amplifier' outputs to 'RF OUT' on the right. Below the main signal path, a 'Power supplier' is connected to 'Power source', 'G' (ground), and 'ALM output'. An 'Alarm administration function' block is connected to the 'ALM output' and also receives input from the 'Electrical amplifier'.](043e64d41a3368d138ace3816fd26469_img.jpg)
+
+Figure B.6 – Configuration of V-ONT. The diagram shows a block diagram of the V-ONT. On the left, 'OPT IN' connects to an 'Optical/electrical converter'. This converter is connected to an 'FM demodulator', which is connected to an 'Electrical amplifier'. The 'Electrical amplifier' outputs to 'RF OUT' on the right. Below the main signal path, a 'Power supplier' is connected to 'Power source', 'G' (ground), and 'ALM output'. An 'Alarm administration function' block is connected to the 'ALM output' and also receives input from the 'Electrical amplifier'.
+
+**Figure B.6 – Configuration of V-ONT**
+
+Pilot signal level or total RF signal power level is observed by the alarm administration function. An alarm is output when the pilot signal level or total RF power level does not meet the specified value. This alarm indicates whether there is a transmission signal error or not.
+
+#### B.4.2 Main characteristics of V-ONT
+
+Table B.7 shows main characteristics of V-ONT.
+
+**Table B.7 – Main characteristics of V-ONT**
+
+| Item and parameter |                            | Limit and specification | Meaning and condition                                                     |
+|--------------------|----------------------------|-------------------------|---------------------------------------------------------------------------|
+| Optical input      | Minimum input power (Note) | $\leq -15$ dBm          | When an O/E device is APD.                                                |
+|                    |                            | $\leq -12$ dBm          | When an O/E device is PIN-PD.                                             |
+|                    | Wavelength, $\lambda$      | $1555 \pm 5$ nm         |                                                                           |
+| Electrical output  | Power level                | $\geq 80$ dB $\mu$ V    | Levels are for analogue channels. Digital channels will be 6-10 dB lower. |
+|                    | VSWR                       | $\leq 2.5$              |                                                                           |
+|                    | Impedance                  | $75 \Omega$ unbalanced  |                                                                           |
+
+NOTE – When the V-ONT is integrated in the digital ONT with a single 'triplelexer', optical loss of the triplelexer is recommended to be considered.
+
+#### **B.4.3 Alarm administration items of V-ONT**
+
+Table B.8 lists the alarm item of V-ONT.
+
+**Table B.8 – Alarm administration item of V-ONT**
+
+| <b>Alarm administration item</b> | <b>Symbol</b> | <b>Alarm occurrence conditions</b>                                                                   |
+|----------------------------------|---------------|------------------------------------------------------------------------------------------------------|
+| Output alarm                     | OUT           | When the optical input power level is lower than the specified value or output RF level is abnormal. |
+
+# Appendix I
+
+## FM frequency deviation and minimum received optical power for CATV band of 47 to 864 MHz
+
+(This appendix does not form an integral part of this Recommendation.)
+
+The acceptable level of FM frequency deviation depends on the minimum received optical power, required CNR, and noise bandwidth. The last two values depend on the modulation format of the video signal. In the FM conversion system, which is specified in this Recommendation, the transmitted signals are given an amplitude tilt of 12.9 dB to compensate the triangular noise created by FM modulation. Therefore, the FM frequency deviation of the  $j$ th carrier is given by Equation I.1.
+
+NOTE – The tilt amplitude of 12.9 dB corresponds to the CATV band of 47 to 864 MHz.
+
+$$\Delta F_j = \Delta F_C \times 10^{\frac{12.9(f_j-f_c)}{16340}} \text{ [MHz}_{0-p}\text{/carrier]} \quad (I.1)$$
+
+Here,  $\Delta F_C$  [MHz] is the FM frequency deviation of the carrier, which has centre frequency of  $f_c$  [MHz].  $f_j$  [MHz] is the frequency of the  $j$ th carrier. Substituting these assumed values and Equation I.1 into the formula described in clause A.1.3 yields the formula shown below.
+
+$$\sqrt{\sum_j^N \Delta F_j^2} = \Delta F_C \sqrt{\sum_j^N 10^{\frac{12.9(f_j-f_c)}{8170}}} \leq 717.5 \quad \text{[MHz}_{0-p}\text{]} \quad (I.2)$$
+
+$$\Rightarrow \Delta F_C \leq \frac{717.5}{\sqrt{\sum_j^N 10^{\frac{12.9(f_j-f_c)}{8170}}}} \quad \text{[MHz}_{0-p}\text{/carrier]}$$
+
+Required minimum received optical power,  $P_{min}$ , is given by Equation I.3.
+
+$$P_{min} = \frac{e + \sqrt{e^2 + \alpha \times (2eI_{do} + N_{th}^2)}}{\alpha \times R} \quad \text{[W]} \quad (I.3)$$
+
+Here,  $e$  is the charge of the electron,  $R$  is the quantum efficiency of the photo detector in V-ONT,  $I_{do}$  is the dark current,  $N_{th}$  is the thermal noise.  $\alpha$  is given by Equation I.4.
+
+$$\alpha = \frac{(m \times \Delta F_C)^2}{4B_W f_C^2 \times CNR_{req}} - \frac{\Delta \nu \times m^2}{4\pi f_C^2} - RIN \quad \text{[s]} \quad (I.4)$$
+
+Here,  $m$  is the modulation index of the transmitted FM signal,  $B_W$  is noise bandwidth,  $CNR_{req}$  is required CNR,  $\Delta \nu$  is the FM signal spectrum line width, and  $RIN$  is the relative intensity noise of optical signal launched into V-ONT. In Equation I.4, the carrier power of  $CNR_{req}$  is measured as peak envelope power. The assumed values for all these parameters are the following:
+
+$$\begin{aligned} \Delta \nu & 50 \text{ kHz} \\ RIN & -135.5 \text{ dB/Hz} \\ I_{do} & 100 \text{ nA} \\ R & 0.8 \text{ A/W} \\ N_{th} & 15 \text{ pA}/\sqrt{\text{Hz}} \\ m & 0.7 \end{aligned}$$
+
+The following conditions are assumed:
+
+|                                         |                                            |
+|-----------------------------------------|--------------------------------------------|
+| Modulation format of transmitted signal | 64-QAM of Annex B of [ITU-T J.83]          |
+| Carrier frequency                       | Ranges from 93 MHz to 747 MHz, 6 MHz steps |
+| Number of carriers, $N$                 | 110                                        |
+| Centre carrier frequency, $f_C$         | 420 MHz                                    |
+
+By substituting these values into Equation I.2, 61.0 [MHz<sub>0-p</sub>/carrier] is determined to be the maximum FM frequency deviation ( $\Delta F_C$ ). Therefore, the  $\Delta F_j$  of this condition is given by Equation I.5.
+
+$$\Delta F_j = 61.0 \times 10^{\frac{12.9(f_j - 420)}{16340}} \text{ [MHz}_{0\text{-p}}\text{/carrier]} \quad (\text{I.5})$$
+
+Thus, the required minimum received optical power,  $P_{min}$ , is calculated to be  $-14.7$  dBm.
+
+# Appendix II
+
+## FM frequency deviation and minimum received optical power for CATV band of 47 to 2100 MHz
+
+(This appendix does not form an integral part of this Recommendation.)
+
+The acceptable level of FM frequency deviation depends on the minimum received optical power, required CNR, and noise bandwidth. The last two values depend on the modulation format of the video signal. In the FM conversion system specified in this Recommendation, the transmitted signals are given an amplitude tilt of 12.9 dB and 8.4 dB to compensate the triangular noise created by FM modulation. Therefore, the FM frequency deviation of the  $j$ th carrier is given by Equations II.1 and II.2.
+
+NOTE – The tilt amplitude of 12.9 dB and 8.4 dB corresponds to the CATV band of 47 MHz to 864 MHz and satellite intermediate frequency band of 1000 MHz to 2150 MHz, respectively.
+
+$$\Delta F_j = \Delta F_C \times 10^{\frac{12.9(f_j-f_C)}{16340}} \text{ [MHz}_{0\text{-p}}\text{/carrier]} \quad (\text{II.1})$$
+
+$$\Delta F_j = \Delta F_{SAT} \times 10^{\frac{8.4(f_j-f_{SAT})}{23000}} \text{ [MHz}_{0\text{-p}}\text{/carrier]} \quad (\text{II.2})$$
+
+Here,  $\Delta F_C$  [MHz] is the FM frequency deviation of the carrier, which has centre frequency of  $f_C$  [MHz] for 47 to 864 MHz, and  $\Delta F_{SAT}$  [MHz] is the FM frequency deviation of the carrier, which has lowest frequency of  $f_{SAT}$  for 1000 MHz to 2150 MHz.  $f_j$  [MHz] is the frequency of the  $j$ th carrier.  $\Delta F_{SAT}$  is obtained with Equation II.1 by substituting  $f_{SAT}$  for  $f_j$  and adjusting the difference in required CNR with peak power and noise bandwidth from 64QAM, by 11.3 dB. Substituting these assumed values and Equations II.1 and II.2 into the formula described in clause B.1.3 yields the formula shown below.
+
+$$\begin{aligned} \sqrt{\sum_j^N \Delta F_j^2} &= \Delta F_C \sqrt{\sum_j^{N_1} 10^{\frac{12.9(f_j-f_C)}{8170}} + 10^{\frac{-11.3}{10}} \sum_j^{N_2} 10^{\frac{8.4(f_j-f_{SAT})}{11500}}} \leq 700 \quad \text{[MHz}_{0\text{-p}}\text{]} \\ \Rightarrow \Delta F_C &\leq \frac{700}{\sqrt{\sum_j^{N_1} 10^{\frac{12.9(f_j-f_C)}{8170}} + 10^{\frac{-11.3}{10}} \sum_j^{N_2} 10^{\frac{8.4(f_j-f_{SAT})}{11500}}}} \quad \text{[MHz}_{0\text{-p}}\text{/carrier]} \end{aligned} \quad (\text{II.3})$$
+
+$N_1$  and  $N_2$  are the number of carriers for 47 MHz to 864 MHz band and for 1000 MHz to 2150 MHz band, respectively.
+
+Required minimum received optical power,  $P_{min}$ , is given by Equation II.4.
+
+$$P_{min} = \frac{e + \sqrt{e^2 + \alpha \times (2eI_{do} + N_{th}^2)}}{\alpha \times R} \quad \text{[W]} \quad (\text{II.4})$$
+
+Here,  $e$  is the charge of the electron,  $R$  is the quantum efficiency of the photo detector in V-ONT,  $I_{do}$  is the dark current,  $N_{th}$  is the thermal noise.  $\alpha$  is given by Equation II.5.
+
+$$\alpha = \frac{(m \times \Delta F_C)^2}{4B_W f_C^2 \times CNR_{req}} - \frac{\Delta v \times m^2}{4\pi f_C^2} - RIN \quad \text{[s]} \quad (\text{II.5})$$
+
+Here,  $m$  is the modulation index of the transmitted FM signal,  $B_W$  is noise bandwidth,  $CNR_{req}$  is required CNR,  $\Delta\nu$  is the FM signal spectrum line width, and  $RIN$  is the relative intensity noise of optical signal launched into V-ONT. In Equation II.5, the carrier power of  $CNR_{req}$  is measured as peak envelope power. The assumed values for these parameters are as follows:
+
+$$\Delta\nu \quad 50 \text{ kHz}$$
+
+$$RIN \quad -136 \text{ dB/Hz}$$
+
+$$I_{do} \quad 100 \text{ nA}$$
+
+$$R \quad 0.9 \text{ A/W}$$
+
+$$N_{th} \quad 15 \text{ pA}/\sqrt{\text{Hz}}$$
+
+$$m \quad 0.7$$
+
+The following conditions are assumed:
+
+Modulation format of transmitted signal    64-QAM of Annex B of [ITU-T J.83] and TC8PSK
+
+Carrier frequency    Ranges from 93 MHz to 747 MHz, 6 MHz steps for 64QAM, and from 1049.48 MHz to 1471.44 MHz, 38.38 MHz steps and from 1613 MHz to 2053 MHz, 40 MHz steps for TC8PSK based on the intermediate frequency allocation of the digital satellite video signals in Japan
+
+Number of carriers,  $N$     110 for 64QAM and 24 for TC8PSK
+
+Centre carrier frequency of 64 QAM,  $f_c$     420 MHz
+
+By substituting these values into Equation II.3, 51.5 [MHz<sub>0-p</sub>/carrier] is determined to be the maximum FM frequency deviation ( $\Delta F_C$ ). Therefore, the  $\Delta F_j$  for 64 QAM and TC8PSK of this condition is given by Equations II.6 and II.7.
+
+$$\Delta F_j = 51.5 \times 10^{\frac{12.9(f_j-420)}{16340}} \text{ [MHz}_{0\text{-p}}\text{/carrier]} \quad (\text{II.6})$$
+
+$$\Delta F_j = 44.0 \times 10^{\frac{8.4(f_j-1049.48)}{23000}} \text{ [MHz}_{0\text{-p}}\text{/carrier]} \quad (\text{II.7})$$
+
+Thus, the required minimum received optical power,  $P_{min}$ , is calculated to be  $-14.6 \text{ dBm}$ .
+
+# Bibliography
+
+- [b-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.*
+- [b-ITU-T G.983.1] Recommendation ITU-T G.983.1 (2005), *Broadband optical access systems based on Passive Optical Networks (PON).*
+- [b-ITU-T G.983.3] Recommendation ITU-T G.983.3 (2001), *A broadband optical access system with increased service capability by wavelength allocation; Amendment 1 (2005).*
+- [b-ITU-T G.984.1] Recommendation ITU-T G.984.1 (2008), *Gigabit-capable Passive Optical Networks (G-PON): General characteristics.*
+- [b-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; Amendment 1 (2006).*
+- [b-ITU-T G.984.3] Recommendation ITU-T G.984.3 (2008), *Gigabit-capable Passive Optical Networks (G-PON): Transmission convergence layer specification.*
+- [b-ITU-T G.984.5] Recommendation ITU-T G.984.5 (2007), *Gigabit-capable Passive Optical Networks (G-PON): Enhancement band.*
+- [b-ITU-T G.987.1] Recommendation ITU-T G.987.1 (2010), *10-Gigabit-capable passive optical networks (XG-PON): General requirements.*
+- [b-ITU-T G.987.2] Recommendation ITU-T G.987.2 (2010), *10-Gigabit-capable passive optical networks (XG-PON): Physical media dependent (PMD) layer specification.*
+- [b-ITU-T K.44] Recommendation ITU-T K.44 (2011), *Resistibility tests for telecommunication equipment exposed to overvoltages and overcurrents – Basic Recommendation.*
+- [b-ITU-R V.662-3] Recommendation ITU-R V.662-3 (2000), *Terms and definitions.*
+- [b-IEEE 802.3] IEEE Standard 802.3 (2008), *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-IEEE 802.3av] IEEE Standard 802.3av (2009), *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 Amendment 1: Physical Layer Specifications and Management Parameters for 10 Gb/s Passive Optical 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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/J/T-REC-J.19-198811-I_PDF-E/raw.md b/marked/J/T-REC-J.19-198811-I_PDF-E/raw.md
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index 0000000000000000000000000000000000000000..a122d033ba4e73cbc2d45d030c1654ccc71f1478
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+++ b/marked/J/T-REC-J.19-198811-I_PDF-E/raw.md
@@ -0,0 +1,167 @@
+
+
+![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**
+
+**J.19**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**TELEVISION AND SOUND TRANSMISSION**
+
+---
+
+**A CONVENTIONAL TEST SIGNAL  
+SIMULATING SOUND - PROGRAMME SIGNALS  
+FOR MEASURING INTERFERENCE IN OTHER  
+CHANNELS**
+
+**ITU-T Recommendation J.19**
+
+(Extract from the *Blue Book*)
+
+---
+
+# NOTES
+
+1 ITU-T Recommendation J.19 was published in Fascicle III.6 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.
+
+## A CONVENTIONAL TEST SIGNAL SIMULATING SOUND-PROGRAMME SIGNALS FOR MEASURING INTERFERENCE IN OTHER CHANNELS<sup>2)</sup>
+
+(Geneva, 1980)
+
+The CCITT,
+
+*considering*
+
+- (a) that on FDM systems non-linear crosstalk may cause mutual interference between the several types of transmission channels;
+- (b) that the interference depends on the total loading of the FDM system;
+- (c) that the interference in a channel can be measured as a noticeable deterioration of the signal-to-noise ratio;
+- (d) that for setting realistic performance limits of interference, a conventional test signal imitating the sound-programme channel loading is desirable,
+
+*unanimously recommends*
+
+that for simulating sound-programme signals a conventional test signal with the following parameters should be used:
+
+- (1) a uniform spectrum energizing signal covering the frequency band up to at least 15 kHz shall be shaped according to the nominal insertion loss/frequency shown in Table 1/J.19 and Figure 1/J.19;
+
+![Figure 1/J.19: Insertion loss (a in dB) versus frequency (f in Hz). The graph is a semi-logarithmic plot. The vertical axis represents insertion loss 'a' in dB, ranging from -10 at the top to 60 at the bottom. The horizontal axis represents frequency 'f' in Hz on a logarithmic scale from 10 to 10^5. The curve starts at approx 15 dB at 20 Hz, rises to a peak of 0 dB at 200 Hz, stays relatively flat until 1000 Hz, then drops sharply to 55 dB at 100,000 Hz.](9ccd03fe518c562a3fe2d3119f50935e_img.jpg)
+
+| Frequency $f$ (Hz) | Insertion loss $a$ (dB) |
+|--------------------|-------------------------|
+| 20                 | 15                      |
+| 50                 | 5                       |
+| 100                | 2                       |
+| 200                | 0                       |
+| 500                | 3                       |
+| 1000 ( $10^3$ )    | 10                      |
+| 2000               | 12                      |
+| 5000               | 25                      |
+| 10000 ( $10^4$ )   | 35                      |
+| 20000              | 45                      |
+| 50000              | 55                      |
+
+Figure 1/J.19: Insertion loss (a in dB) versus frequency (f in Hz). The graph is a semi-logarithmic plot. The vertical axis represents insertion loss 'a' in dB, ranging from -10 at the top to 60 at the bottom. The horizontal axis represents frequency 'f' in Hz on a logarithmic scale from 10 to 10^5. The curve starts at approx 15 dB at 20 Hz, rises to a peak of 0 dB at 200 Hz, stays relatively flat until 1000 Hz, then drops sharply to 55 dB at 100,000 Hz.
+
+FIGURE 1/J.19  
+**Insertion local frequency**
+
+- (2) the conventional test signal can be produced from a Gaussian white noise generator associated with a shaping network conforming with Figure 2/J.19;
+
+1) This Recommendation corresponds to CCIR Recommendation 571.
+
+2) For the definitions of absolute power, relative power and noise levels, see CCIR Recommendation 574
+
+(3) the total test signal power applied to a sound-programme circuit under test shall be cyclically changed in level according to Table 2/J.19.
+
+*Note* – This Recommendation is derived from studies given in Report 497.
+
+![Circuit diagram of a sound-programme circuit model. It shows a source on the left connected to a network of resistors, capacitors, and inductors. The source is represented by a circle with a sine wave symbol, in series with a 600 Ω resistor. The network consists of a 2.0 μF capacitor, a 10 Ω resistor, a 0.05 H inductor, an 80 Ω resistor, a 0.5 H inductor, a 0.1 μF capacitor, a 600 Ω resistor, a 27 Ω resistor, a 10.0 μF capacitor, and a 600 Ω load resistor on the right. Vertical dashed lines indicate the input and output ports. The diagram is labeled CCITT-38960.](9e6062272bbe3ddbb7c0606721d64cf0_img.jpg)
+
+Circuit diagram of a sound-programme circuit model. It shows a source on the left connected to a network of resistors, capacitors, and inductors. The source is represented by a circle with a sine wave symbol, in series with a 600 Ω resistor. The network consists of a 2.0 μF capacitor, a 10 Ω resistor, a 0.05 H inductor, an 80 Ω resistor, a 0.5 H inductor, a 0.1 μF capacitor, a 600 Ω resistor, a 27 Ω resistor, a 10.0 μF capacitor, and a 600 Ω load resistor on the right. Vertical dashed lines indicate the input and output ports. The diagram is labeled CCITT-38960.
+
+FIGURE 2/J.19
+
+TABLE 1/J.19
+
+| Frequency<br>(Hz) | Relative insertion-loss<br>(dB) | Tolerance<br>( $\pm$ dB) |
+|-------------------|---------------------------------|--------------------------|
+| 31.5              | 10.9                            | 0.5                      |
+| 63                | 3.4                             | 0.3                      |
+| 100               | 0.4                             | 0.2                      |
+| (122)             | (0.0)                           | (0)                      |
+| 200               | 1.5                             | 0.2                      |
+| 400               | 5.7                             | 0.3                      |
+| 800               | 8.7                             | 0.3                      |
+| 1 000             | 9.2                             | 0.3                      |
+| 2 000             | 10.6                            | 0.5                      |
+| 3 150             | 13.0                            | 0.5                      |
+| 4 000             | 15.7                            | 0.5                      |
+| 5 000             | 18.8                            | 0.5                      |
+| 6 300             | 22.5                            | 0.5                      |
+| 7 100             | 24.6                            | 0.5                      |
+| 8 000             | 26.6                            | 0.5                      |
+| 9 000             | 28.6                            | 0.5                      |
+| 10 000            | 30.4                            | 1.0                      |
+| 12 500            | 34.3                            | 1.0                      |
+| 14 000            | 36.3                            | 1.0                      |
+| 16 000            | 38.6                            | 1.0                      |
+| 20 000            | 42.5                            | 1.0                      |
+| 31 500            | 50.4                            | 1.0                      |
+
+TABLE 2/J.19
+
+| Step | Level     | Time for which signal is applied |
+|------|-----------|----------------------------------|
+| 1    | - 4 dBm0s | 4 s                              |
+| 2    | + 3 dBm0s | 2 s                              |
+| 3    | no signal | 2 s                              |
+
+## ANNEX A
+
+(to Recommendation J.19)
+
+Study Group XV of the CCITT had put some questions as regards CCIR Recommendation 571 and the CMTT has worked out their answers. As those questions and the answers may be helpful for anyone who applies the conventional test signal for carrying out measurements of any kind, they are given below:
+
+### *Question*
+
+- a) For the measurement of crosstalk from a sound-programme circuit to a telephone circuit, could the signal described in CCIR Recommendation 571 be used, considering the different bandwidth and possible frequency shift?
+
+### *Reply:*
+
+- The intelligible crosstalk ratio is based on selective measurements in the telephone circuit when the sinusoidal signals are transmitted in the sound-programme circuit within the frequency range of 0.3 to 3.4 kHz. In Recommendation J.21 a minimum ratio of 65 dB is defined.
+- The unintelligible crosstalk ratio should be ascertained by measuring the increase of noise in the telephone circuit by loading the disturbing sound-programme with the simulated test signal defined in CCIR Recommendation 571. As for this increase no tolerable values are recommended up to now, the CMTT proposes such values based on a maximum noise contribution produced by interference of -65 dBm0p. Depending on the basic noise level in the telephone circuit the following increased values can be tolerated:
+
+TABLE A-1/J.19
+
+|                                        |      |      |      |      |      |      |
+|----------------------------------------|------|------|------|------|------|------|
+| Basic noise level (dBm0p)              | - 75 | - 70 | - 65 | - 60 | - 55 | - 50 |
+| Tolerable increase of noise level (dB) | 10.4 | 6.2  | 3    | 1.2  | 0.4  | 0.1  |
+
+### *Question*
+
+- b) What is the equivalent value for 65 dB ratio (given in Recommendations J.21, J.22 and J.23) using sinusoidal tones, when measuring with the recommended new test signal?
+
+### *Reply:*
+
+The answer to this question is included in the proposal for the measurement of the ratio for the total crosstalk caused by intermodulation given in the answer to Question a).
+
+### *Question*
+
+- c) Can the signal defined in Table 2/J.19, from the point of view of the mean loading it would impose on transmission systems and in the light of Recommendations N.12 and N.13, be regarded as acceptable for unrestricted use over complete sound-programme circuits of any constitution?
+
+### *Reply:*
+
+The conventional test signal simulating sound-programme signals defined in CCIR Recommendation 571/Recommendation J.19 in all aspects can be regarded as acceptable for unrestricted use over sound-programme circuits of any constitution.
\ No newline at end of file
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+
+
+# Recommendation**ITU-T J.195.1 (03/2024)**
+
+SERIES J: Cable networks and transmission of television,  
+sound programme and other multimedia signals
+
+Cable modems and home networking
+
+## --- **Functional requirements for first-generation HiNOC**
+
+![ITU logo](0538daaa5583c23e17db3a12f2281a55_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 J-SERIES RECOMMENDATIONS
+
+# **Cable networks and transmission of television, sound programme and other multimedia signals**
+
+|                                                                                                 |                    |
+|-------------------------------------------------------------------------------------------------|--------------------|
+| GENERAL RECOMMENDATIONS                                                                         | J.1-J.9            |
+| GENERAL SPECIFICATIONS FOR ANALOGUE SOUND-PROGRAMME TRANSMISSION                                | J.10-J.19          |
+| PERFORMANCE CHARACTERISTICS OF ANALOGUE SOUND-PROGRAMME CIRCUITS                                | J.20-J.29          |
+| EQUIPMENT AND LINES USED FOR ANALOGUE SOUND-PROGRAMME CIRCUITS                                  | J.30-J.39          |
+| DIGITAL ENCODERS FOR ANALOGUE SOUND-PROGRAMME SIGNALS - PART 1                                  | J.40-J.49          |
+| DIGITAL TRANSMISSION OF SOUND-PROGRAMME SIGNALS                                                 | J.50-J.59          |
+| CIRCUITS FOR ANALOGUE TELEVISION TRANSMISSION                                                   | J.60-J.69          |
+| ANALOGUE TELEVISION TRANSMISSION OVER METALLIC LINES AND INTERCONNECTION WITH RADIO-RELAY LINKS | J.70-J.79          |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS                                                      | J.80-J.89          |
+| ANCILLARY DIGITAL SERVICES FOR TELEVISION TRANSMISSION                                          | J.90-J.99          |
+| OPERATIONAL REQUIREMENTS AND METHODS FOR TELEVISION TRANSMISSION                                | J.100-J.109        |
+| INTERACTIVE SYSTEMS FOR DIGITAL TELEVISION DISTRIBUTION (DOCSIS FIRST AND SECOND GENERATIONS)   | J.110-J.129        |
+| TRANSPORT OF MPEG-2 SIGNALS ON PACKETIZED NETWORKS                                              | J.130-J.139        |
+| MEASUREMENT OF THE QUALITY OF SERVICE - PART 1                                                  | J.140-J.149        |
+| DIGITAL TELEVISION DISTRIBUTION THROUGH LOCAL SUBSCRIBER NETWORKS                               | J.150-J.159        |
+| IPCABLECOM (MGCP-BASED) - PART 1                                                                | J.160-J.179        |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS - PART 1                                             | J.180-J.189        |
+| <b>CABLE MODEMS AND HOME NETWORKING</b>                                                         | <b>J.190-J.199</b> |
+| APPLICATION FOR INTERACTIVE DIGITAL TELEVISION - PART 1                                         | J.200-J.209        |
+| INTERACTIVE SYSTEMS FOR DIGITAL TELEVISION DISTRIBUTION (DOCSIS THIRD TO FIFTH GENERATIONS)     | J.210-J.229        |
+| MULTI-DEVICE SYSTEMS FOR CABLE TELEVISION                                                       | J.230-J.239        |
+| MEASUREMENT OF THE QUALITY OF SERVICE - PART 2                                                  | J.240-J.249        |
+| DIGITAL TELEVISION DISTRIBUTION THROUGH LOCAL SUBSCRIBER NETWORKS                               | J.250-J.259        |
+| IPCABLECOM (MGCP-BASED) - PART 2                                                                | J.260-J.279        |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS - PART 2                                             | J.280-J.289        |
+| CABLE SET-TOP BOX                                                                               | J.290-J.299        |
+| APPLICATION FOR INTERACTIVE DIGITAL TELEVISION - PART 2                                         | J.300-J.309        |
+| MEASUREMENT OF THE QUALITY OF SERVICE - PART 3                                                  | J.340-J.349        |
+| IPCABLECOM2 (SIP-BASED) - PART 1                                                                | J.360-J.379        |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS - PART 3                                             | J.380-J.389        |
+| MEASUREMENT OF THE QUALITY OF SERVICE - PART 4                                                  | J.440-J.449        |
+| IPCABLECOM2 (SIP-BASED) - PART 2                                                                | J.460-J.479        |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS - PART 4                                             | J.480-J.489        |
+| TRANSPORT OF LARGE SCREEN DIGITAL IMAGERY                                                       | J.600-J.699        |
+| SECONDARY DISTRIBUTION OF IPTV SERVICES                                                         | J.700-J.799        |
+| MULTIMEDIA OVER IP IN CABLE                                                                     | J.800-J.899        |
+| TRANSMISSION OF 3-D TV SERVICES                                                                 | J.900-J.999        |
+| CONDITIONAL ACCESS AND PROTECTION                                                               | J.1000-J.1099      |
+| SWITCHED DIGITAL VIDEO OVER CABLE NETWORKS                                                      | J.1100-J.1119      |
+| SMART TV OPERATING SYSTEM                                                                       | J.1200-J.1209      |
+| IP VIDEO BROADCAST                                                                              | J.1210-J.1219      |
+| CLOUD-BASED CONVERGED MEDIA SERVICES FOR IP AND BROADCAST CABLE TELEVISION                      | J.1300-J.1309      |
+| TELEVISION TRANSPORT NETWORK AND SYSTEM DEPLOYMENT IN DEVELOPING COUNTRIES                      | J.1400-J.1409      |
+| ARTIFICIAL INTELLIGENCE (AI) ASSISTED CABLE NETWORKS                                            | J.1600-J.1649      |
+
+For further details, please refer to the list of ITU-T Recommendations.
+
+# Recommendation ITU-T J.195.1
+
+## Functional requirements for first-generation HiNOC
+
+## Summary
+
+Recommendation ITU-T J.195.1 specifies the functional requirements of high performance network over coax (HiNoC) for high-speed data transmission over coaxial networks in the cable industry. Internet protocol (IP) technology is one of the foreseeable trends of the next generation broadcasting network, which needs to fully support triple-play services and the rapidly increasing bandwidth demands for multichannel video services. Therefore, it is necessary to define the functional requirements of HiNoC. This Recommendation contains descriptions of functional requirements for the general system, physical layer (PHY) and medium access control (MAC) layer functions over coaxial networks connected with fibre to the building.
+
+This Recommendation also provides a HiNoC operation-deployment scenario and HiNoC use cases.
+
+Edition 3.0 only updates the title of this and other HiNOC Recommendations without introducing any technical changes.
+
+## History\*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T J.195.1  | 2013-03-01 | 9           | 11.1002/1000/11879 |
+| 2.0     | ITU-T J.195.1  | 2016-03-15 | 9           | 11.1002/1000/12765 |
+| 3.0     | ITU-T J.195.1  | 2024-03-26 | 9           | 11.1002/1000/15879 |
+
+## Keywords
+
+Coaxial network, HiNoC.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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 .....                                       | 1    |
+| 3.1 Terms defined elsewhere .....                         | 1    |
+| 3.2 Terms defined in this Recommendation.....             | 1    |
+| 4 Abbreviations and acronyms .....                        | 2    |
+| 5 Conventions .....                                       | 3    |
+| 6 Architecture .....                                      | 4    |
+| 7 Functional requirements .....                           | 5    |
+| 7.1 General requirements.....                             | 5    |
+| 7.2 System requirements of the PHY layer .....            | 5    |
+| 7.3 System requirements of the MAC layer .....            | 6    |
+| Appendix I – Scenario for HiNoC operation-deployment..... | 7    |
+| Appendix II – Use cases of HiNoC.....                     | 9    |
+| Appendix III – Operational notes.....                     | 10   |
+| Bibliography.....                                         | 11   |
+
+## Introduction
+
+Recommendation ITU-T J.195.1 defines one solution, namely high performance network over coax (HiNoC), to address high-density small office, home office (SOHO) end-user requirements by using fibre to the building (FTTB) infrastructure and coax architecture. HiNoC is layered into the medium access control (MAC) layer and the physical layer (PHY) to fully utilize the unassigned spectrum of the "last 100 m" coaxial network in order to provide more bandwidth and improve the spectral efficiency. HiNoC also supports the operations of existing TV broadcasting services.
+
+###### Recommendation ITU-T J.195.1
+
+## Functional requirements for first-generation HiNOC
+
+# 1 Scope
+
+This Recommendation defines the functional requirements of high performance network over coax (HiNoC) for high-speed data transmission over coaxial networks connected with fibre to the building (FTTB). The functionalities described in this Recommendation are based on FTTB + coax architecture. HiNoC provides more bandwidth with the unassigned spectrum of the last 100 m coaxial network. HiNoC also supports the operations of existing TV broadcasting services.
+
+# 2 References
+
+None.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 access network** [b-ITU-T Q.1742.1]: Network that connects access technologies (such as a radio access network) to the core network.
+
+**3.1.2 data encryption** [b-ITU-T J.191]: Data encryption prevents the unauthorized disclosure/access of data. Data encryption does an excellent job at providing data confidentiality and protection against theft of service. Encryption prevents making data unable to read without the correct decrypting key; however, it does not validate the source/receiving entities and it does not provide copy protection after the data has been decrypted. It also does not prevent DoS attacks.
+
+**3.1.3 dynamic channel allocation** [b-ITU-T F.723]: The principle of allocating in a flexible way the available channel capacity between various types of data, comprising audio, video, control information, still pictures and other application specific data to maximize the quality of service.
+
+**3.1.4 key management** [b-ITU-T J.160]: The process of distributing shared symmetric keys needed to run a security protocol.
+
+**3.1.5 out-of-band attenuation** [b-ITU-T G.671]: The minimum attenuation (in dB) of channels that fall outside of the operating wavelength range.
+
+**3.1.6 packet classification** [b-ITU-T Y.1222]: The process of distinguishing Ethernet frames for the purpose of applying appropriate traffic control and congestion control mechanisms is called Ethernet frame classification.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 address learning**: A process that establishes the mapping between higher layer protocol data unit (PDU) addresses and high performance network over coax (HiNoC) node addresses.
+
+**3.2.2 centralized distribution structure**: A physical structure of a passive coaxial access network and a multiple stage power distribution network realized by splitters only.
+
+**3.2.3 constellation mapping**: The process of mapping data bits to the constellation symbol.
+
+**3.2.4 link maintenance:** The function of estimating and exchanging parameters of links between a master node and client nodes to adapt to the variation of channel characteristics and maintain the steady working of the system.
+
+**3.2.5 node quitting/deletion:** The function to support a client node quitting a high performance network over coax (HiNoC) system or a master node deleting a client node from a HiNoC system.
+
+**3.2.6 package filter:** The process of analysing and selecting a data packet according to the established rule set.
+
+**3.2.7 packing:** A procedure of combining multiple Ethernet medium access control (MAC) frames with the same destination and priority to form a high performance network over coax (HiNoC) MAC frame.
+
+**3.2.8 passive coaxial access network:** An access network composed of a coaxial network and passive power distribution components such as splitters and taps.
+
+**3.2.9 service priority mapping:** A function whereby the medium access control (MAC) layer maps the service stream matching the message features into the assignment priority queue of the quality of service (QoS) level and simultaneously re-labels the priority level of the service stream.
+
+**3.2.10 stream classification:** The process of distinguishing higher layer protocol data units (PDUs) in order to apply appropriate traffic and congestion control mechanisms.
+
+**3.2.11 tree distribution structure:** A physical structure of a passive coaxial access network and a multiple stage power distribution network realized by splitters and taps or by taps only.
+
+**3.2.12 unpacking:** A procedure of dividing a high performance network over coax (HiNoC) medium access control (MAC) frame into individual Ethernet MAC frames; the opposite of packing.
+
+# **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|       |                                         |
+|-------|-----------------------------------------|
+| 3DTV  | three Dimensional Television            |
+| 3G    | third Generation                        |
+| 4G    | fourth Generation                       |
+| AP    | Access Point                            |
+| AWGN  | Additive White Gaussian Noise           |
+| BER   | Bit Error Rate                          |
+| CPS   | Common Part Sublayer                    |
+| CS    | Convergence Sublayer                    |
+| DBA   | Dynamic Bandwidth Allocation            |
+| EMC   | Electromagnetic Compatibility           |
+| FEC   | Forward Error Correction                |
+| FTTB  | Fibre To The Building                   |
+| GSM   | Global System for Mobile communications |
+| HB    | HiNoC Bridge                            |
+| HiNoC | High performance Network over Coax      |
+| HM    | HiNoC Modem                             |
+| IP    | Internet Protocol                       |
+
+|          |                                            |
+|----------|--------------------------------------------|
+| IPv4     | Internet Protocol version 4                |
+| IPv6     | Internet Protocol version 6                |
+| MAC      | Medium Access Control                      |
+| MSO      | Multiple Systems Operator                  |
+| OFDM     | Orthogonal Frequency Division Multiplexing |
+| OLT      | Optical Line Terminal                      |
+| ONU      | Optical Network Unit                       |
+| PDU      | Protocol Data Unit                         |
+| PHY      | Physical layer                             |
+| PON      | Passive Optical Network                    |
+| QoS      | Quality of Service                         |
+| SAP      | Service Access Point                       |
+| SD/HD TV | Signal Degrade/High Definition Television  |
+| SOHO     | Small Office, Home Office                  |
+| SS       | Security Sublayer                          |
+| STB      | Set-Top Box                                |
+| TDD      | Time Division Duplexing                    |
+| TV       | Television                                 |
+| UHDTV    | Ultra High-Definition Television           |
+| VoIP     | Voice over Internet Protocol               |
+| Wi-Fi    | Wireless Fidelity                          |
+
+# 5 Conventions
+
+In this Recommendation:
+
+The keywords "**is required to**" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+
+The keywords "**is recommended**" indicate a requirement which is recommended but which is not absolutely required. Thus this requirement need not be present to claim conformance.
+
+The keywords "**is prohibited from**" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed.
+
+The keywords "**can optionally**" indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+In the body of this Recommendation, the words shall, shall not, should, and may sometimes appear, in which case they are to be interpreted, respectively, as is required to, is prohibited from, is recommended, and can optionally. The appearance of such phrases or keywords in an appendix or in material explicitly marked as informative are to be interpreted as having no normative intent.
+
+# 6 Architecture
+
+The logical architecture model of HiNoC is shown in Figure 1. The model includes two parts: a master node and client nodes. The master node links the passive optical network (PON) and the client nodes link home terminals.
+
+![Figure 1 – HiNoC logical architecture diagram](cfda9df1319e04207eb28bcefd1dab7b_img.jpg)
+
+The diagram illustrates the logical architecture of HiNoC. On the left, a horizontal line labeled 'Data 1/2/3' enters a dashed oval containing a 'Master node'. From the master node, a line labeled 'Data 1/2/3' branches out to three 'Client node' boxes stacked vertically. Each client node is connected to an external line labeled 'Data 1', 'Data 2', and 'Data 3' respectively. The entire system is enclosed in a dashed oval. A label 'J.195.1(13)\_F01' is at the bottom right.
+
+Figure 1 – HiNoC logical architecture diagram
+
+**Figure 1 – HiNoC logical architecture**
+
+A master node supports several registered client nodes and may have an upper limit for the number of registered client nodes. In a network there may be one or several master nodes.
+
+The master node manages the allocation of global coaxial network resources and matches the uplink PON transmission capacity. With reference to the uplink bandwidth availability, the master node assigns each client's upstream and downstream bandwidth based on the balance between the client's bandwidth requests and the dynamic bandwidth allocation (DBA)/quality of service (QoS)/priority configuration. The master node detects and maintains the linkage with clients.
+
+The client node communicates with the master node and provides bandwidth to the connected terminals. The client node identifies the requests of the service flows supported by the terminal and negotiates with the master node for the upstream and downstream bandwidth.
+
+The protocol stack of HiNoC is defined in Figure 2. The protocol stack includes the physical layer (PHY) and medium access control (MAC) layer.
+
+![Figure 2 – HiNoC protocol architecture diagram](54fabc351eda5228d2fa28cd9ba07971_img.jpg)
+
+The diagram shows the HiNoC protocol stack. At the top is the 'Upper ethernet layer'. Below it is a dashed oval labeled 'SAP'. The next section is the 'MAC' layer, which contains three sublayers: 'Convergence sublayer', 'Common part sublayer', and 'Security sublayer'. Each sublayer is separated by a dashed oval labeled 'SAP'. Below the MAC layer is the 'PHY' layer. A vertical double-headed arrow on the left is labeled 'HiNoC', and another on the right is labeled 'MAC' for the upper part and 'PHY' for the lower part. A label 'J.195.1(13)\_F02' is at the bottom right.
+
+Figure 2 – HiNoC protocol architecture diagram
+
+**Figure 2 – HiNoC protocol architecture**
+
+The PHY layer frames the data fed from the MAC layer, modulates the frame after the appropriate channel coding and transmits into the coaxial network, and vice versa.
+
+The MAC layer provides two functions: one is medium access control and the other is service adaptation, and includes the common part sublayer (CPS) and convergence sublayer (CS), and may also include a security sublayer (SS).
+
+The CS provides the adaptation between the CPS and the higher layer including address learning, packet forwarding table generation, service priority mapping and data frame packing/unpacking functions.
+
+The CPS provides MAC, channel and bandwidth allocation, node registration and abortion and linkage maintenance functions.
+
+The SS provides identity authentication, data encryption and key management functions.
+
+# **7 Functional requirements**
+
+## **7.1 General requirements**
+
+[HiNoC-Gen-1] HiNoC is required to be applied to the passive coaxial access network in the premises.
+
+[HiNoC-Gen-2] HiNoC is required to support any IP-based services such as signal degrade/high definition television (SD/HD TV), three dimensional television (3DTV), ultra high-definition television (UHDTV), interactive services, voice over Internet protocol (VoIP) and Internet access.
+
+[HiNoC-Gen-3] HiNoC is required not to affect the adjacent channels which provide services and deployments such as analogue broadcasting, digital broadcasting and data services.
+
+[HiNoC-Gen-4] HiNoC is required to support the tree distribution structure and centralized distribution structure of the coaxial cable access network.
+
+[HiNoC-Gen-5] HiNoC is recommended to be applicable below the 1.2 GHz frequency band on a coaxial network.
+
+[HiNoC-Gen-6] HiNoC is required to be robust enough to resist the interference and micro-reflection in a short-range coaxial environment.
+
+[HiNoC-Gen-7] HiNoC is required to allocate downstream/upstream bandwidth flexibly (symmetrical/asymmetrical scenario).
+
+[HiNoC-Gen-8] HiNoC is required to support 16 MHz bandwidth per channel.
+
+[HiNoC-Gen-9] HiNoC is required to support channel bonding to provide more transmission rate.
+
+[HiNoC-Gen-10] HiNoC is required to be able to schedule the time-slot for the master node and client node to send or receive.
+
+[HiNoC-Gen-11] HiNoC is required to support the end-to-end OAM integration with PON.
+
+[HiNoC-Gen-12] HiNoC is required to avoid spectrum overlap to existing cable services.
+
+[HiNoC-Gen-13] The screening attenuation of the coaxial cable to connect HiNoC system is required to be higher than 60 dB.
+
+## **7.2 System requirements of the PHY layer**
+
+[HiNoC-PHY-1] HiNoC PHY is required to be based on the orthogonal frequency division multiplexing (OFDM) modulation.
+
+[HiNoC-PHY-2] HiNoC PHY is required to support the adaptive constellation mapping function for each OFDM sub-carrier in accordance with channel conditions in the coaxial network.
+
+[HiNoC-PHY-3] HiNoC PHY is required to support the flexible forward error correction (FEC) encoding rate in accordance with channel conditions in the coaxial network.
+
+[HiNoC-PHY-4] HiNoC PHY is required to satisfy out-of-band attenuation to reduce the adjacent channel interference in the coaxial network.
+
+[HiNoC-PHY-5] HiNoC PHY is required to perform channel estimation in the connections between the master node and client nodes.
+
+## **7.3 System requirements of the MAC layer**
+
+### **7.3.1 System requirements of the CS layer**
+
+[HiNoC-MAC-1] HiNoC MAC is required to support the address learning function.
+
+[HiNoC-MAC-2] HiNoC MAC is required to support the packing/unpacking of data frames function.
+
+[HiNoC-MAC-3] HiNoC MAC is required to support Internet protocol version 4 (IPv4) and Internet protocol version 6 (IPv6).
+
+[HiNoC-MAC-4] HiNoC MAC is required to support the DBA function.
+
+[HiNoC-MAC-5] HiNoC MAC is required to support the service priority mapping function.
+
+[HiNoC-MAC-6] HiNoC MAC is required to support the stream classification function.
+
+[HiNoC-MAC-7] HiNoC MAC is required to support the QoS control function.
+
+[HiNoC-MAC-8] HiNoC MAC is recommended to support the multicast services management and packet filter function.
+
+### **7.3.2 System requirements of the CPS layer**
+
+[HiNoC-MAC-9] HiNoC MAC is required to support the channel allocation function.
+
+[HiNoC-MAC-10] HiNoC MAC is required to support the node quitting/deletion function.
+
+[HiNoC-MAC-11] HiNoC MAC is required to support the link maintenance function.
+
+### **7.3.3 System requirements of the SS layer**
+
+[HiNoC-MAC-12] HiNoC MAC is required to support the identity function.
+
+[HiNoC-MAC-13] HiNoC MAC is required to support the authentication function.
+
+[HiNoC-MAC-14] HiNoC MAC is required to support the data encryption function.
+
+[HiNoC-MAC-15] HiNoC MAC is required to support the key management function.
+
+## Appendix I
+
+## Scenario for HiNoC operation-deployment
+
+(This appendix does not form an integral part of this Recommendation.)
+
+Cable operators around the world are interested in deploying triple-play services over cable television systems while supporting existing analogue or digital TV broadcasting services. Most triple-play services with video content require a very high-speed access network.
+
+In high-density residential or office areas, FTTB and coax solutions have been introduced. A typical network scenario is shown in Figure I.1. The FTTB + coax network can be realized by the PON system in the distribution network and the HiNoC system in a coaxial network. Services such as analogue or digital TV, VoIP, Internet access and interactive services can be transferred over the network.
+
+![Diagram of FTTB + coax network architecture showing Service, Backbone, Distribution, and Coax in building sections.](410562339ce067fdc6fa41940c118658_img.jpg)
+
+The diagram illustrates the network architecture for FTTB + coax. It is divided into four main sections by vertical dashed lines: Service, Backbone, Distribution, and Coax in building.
+
+- Service:** Includes icons for Analogue/Digital TV, Interactive service, VoIP, and Internet.
+- Backbone:** A cloud labeled "Backbone" connected to the Service section.
+- Distribution:** Contains an OLT (Optical Line Terminal) connected to the Backbone. A fibre optic cable runs from the OLT through an Optical splitter to an ONU (Optical Network Unit). This section is labeled "PON" at the bottom.
+- Coax in building:** The ONU connects to a Coax network via a HiNoC Bridge (HB). The Coax network includes Tap(s) and Coaxial splitter(s). Inside a building, the network connects to multiple HiNoC Modems (HM) and an Access Point (AP). These devices provide services to various endpoints: Internet access (laptop), Telephony (phone), Digital TV, and Analogue TV (two instances shown). This section is labeled "HiNoC" at the bottom.
+
+The diagram is labeled "J.195.1(16)\_FI.1" in the bottom right corner.
+
+Diagram of FTTB + coax network architecture showing Service, Backbone, Distribution, and Coax in building sections.
+
+**Figure I.1 – FTTB + coax**
+
+HiNoC is a broadband access technology over coax. It is designed to provide high performance bidirectional data transmission by improving the spectral efficiency of the cable.
+
+The intended services such as IP traffic can be transferred transparently and bidirectionally over a passive coaxial access network. The overall transmission paths between the head-end and the customers are realized by the HiNoC system, which includes the HiNoC bridge (HB) at the head-end and HiNoC modem (HM) on the customer side. With reference to Figure 1, an HB is the device form of the master node and an HM is the device form of the client nodes.
+
+As shown in Figure I.1, the coaxial distribution network deployed in the building can be composed of tap(s), distributor(s) and coaxial cable, which are all passive components. A wide frequency band of up to the 1.2 GHz frequency band can be used. The attenuation is limited due to the short-range transmission within a building.
+
+Another channel characteristic in the coaxial network is the multipath reflection caused by the open branches and impedance mismatching, which results in deep fading points in the frequency domain. OFDM technology, which is employed in HiNoC systems, is suitable in this scenario because of its immunity to the multipath effects.
+
+There are several interference sources in the coaxial network, such as narrow-band interference, impulse interference and consumer electrical device interference. These interference noises originate from the home electricity or wireless signal crosstalk. As a result, in addition to the additive white Gaussian noise (AWGN) and the impulse noise, it is necessary to take the test results in the real coaxial network into account while building the channel model.
+
+Since the HiNoC services are multiplexed in the frequency domain with existing TV broadcasting services and IP data transmission services in the coaxial network, the transmit power density of HiNoC should satisfy the adjacent channel protection requirement. Several sub-carriers in the high frequency bands of each OFDM symbol are assigned as null to get better roll-off performance in the HiNoC technology. The out-band interference is therefore greatly reduced.
+
+There are three types of triple-play services (video, voice and data), each of which has its own specific performance requirements. For the video service, both broad bandwidth and low bit error rate (BER) are needed. However, for the voice service, real-time service is more important, which means lower latency and jitter and therefore the access system should be carefully designed to guarantee different QoS elements, such as priority, latency and jitter.
+
+Due to the diversity and uncertainty of the future service, the characteristics of the service flow and the requirements of the network-supporting capability are hard to predict. It is necessary for an access technology to make a real-time response dynamically according to the downstream and upstream bandwidth allocation. Therefore, time division duplexing (TDD) is the recommended solution.
+
+To meet the tough demands for dedicated network resources management and diversified service-specific transmission requirements, MAC mechanisms such as DBA and flow classifier should be adopted to ensure fulfilment of the various QoS requirements. Multicast is needed to save bandwidth costs. IPv4, IPv6 or both forms of IP addressing should also be supported in the HiNoC system.
+
+## Appendix II
+
+## Use cases of HiNoC
+
+(This appendix does not form an integral part of this Recommendation.)
+
+HiNoC networking use cases are presented in Figure II.1. In use case 1, a PON transmits TV signals and IP services in one physical channel and the HB connects only to the PON and supports the multi-services. In use case 2, the analogue/digital TV signal is from one physical channel and IP services are from another. In use case 2, the HB has two ports to access to the multi-services, one for analogue/digital TV and the other for IP services. HiNoC supports the point-to-point unicast service and point-to-multi-point multicast services.
+
+![Figure II.1 – HiNoC networking use cases. The diagram shows two use cases. Use case 1 shows a PON connected to an HB, which is connected to a coaxial cable with tap(s) and splitter(s), leading to two HM (Home Module) units. The PON provides Analogue/Digital TV and IP services. Use case 2 shows a PON connected to an HB, which is connected to a coaxial cable with tap(s) and splitter(s), leading to two HM (Home Module) units. The PON provides IP services, and an Optical Rx provides Analogue/Digital TV to the HB. The diagram is labeled J.195.1(16)_FII.1.](75f0cb39f1cd165dfe4a6aa6c4d9388d_img.jpg)
+
+The diagram illustrates two HiNoC networking use cases. In use case 1, a PON (Packet Optical Network) provides both Analogue/Digital TV and IP services to an HB (Home Box). The HB is connected to a coaxial cable that branches through tap(s) and splitter(s) to two HM (Home Module) units. In use case 2, the PON provides IP services to the HB, while an Optical Rx provides Analogue/Digital TV to the HB. The HB is connected to a coaxial cable that branches through tap(s) and splitter(s) to two HM (Home Module) units. The diagram is labeled J.195.1(16)\_FII.1.
+
+Figure II.1 – HiNoC networking use cases. The diagram shows two use cases. Use case 1 shows a PON connected to an HB, which is connected to a coaxial cable with tap(s) and splitter(s), leading to two HM (Home Module) units. The PON provides Analogue/Digital TV and IP services. Use case 2 shows a PON connected to an HB, which is connected to a coaxial cable with tap(s) and splitter(s), leading to two HM (Home Module) units. The PON provides IP services, and an Optical Rx provides Analogue/Digital TV to the HB. The diagram is labeled J.195.1(16)\_FII.1.
+
+Figure II.1 – HiNoC networking use cases
+
+HiNoC supports a 16 MHz bandwidth per channel and each channel can be deployed in any spectrum window below the 1.2 GHz frequency band and can be allocated beside or between the analogue TV, digital TV or data service channels. HiNoC signal transmission will not interfere with adjacent channels and supports channel bounding to provide a higher access rate. An HB supports up to 64 registered HMs.
+
+HiNoC has several possible equipment models. For instance, the HB can be a single device and can be situated in an optical network unit (ONU) of the PON as a module. The HM can also be a single transmission device and can be situated in a set-top box (STB) as a service terminal.
+
+## **Appendix III**
+
+## **Operational notes**
+
+(This appendix does not form an integral part of this Recommendation.)
+
+The possible interference from or to the wireless signal or radiocommunication services, such as terrestrial broadcast, global system for mobile communications (GSM), third/fourth generation (3G/4G), wireless fidelity (Wi-Fi) and aeronautical navigation, might cause the signal or service quality to deteriorate both in the coaxial cable and in air, and can even be risky to flight safety in the worst case scenario. Therefore, any multiple systems operator (MSO) which plans to deploy HiNoC should be cautious about spectrum allocation, coaxial cable mounting and maintenance, and equipment screening to minimize the risk from and to any other possible signal outside the coaxial cable. Specifically, any deployment of HiNoC should not to be closer than 1 km from any airport.
+
+Frequency planning, safety and electromagnetic compatibility (EMC) requirements are a national matter and are not covered by this Recommendation. Compliance remains the operators' responsibility; operators who need to calculate or estimate the EMC conditions of their network should refer to [b-ITU-R P.525-2], [b-ITU-R P.528-3] and [b-ITU-R P.1238-8].
+
+## Bibliography
+
+- [b-ITU-T F.723] Recommendation ITU-T F.723 (1996), *Videophone service in the Public Switched Telephone Network (PSTN)*.
+- [b-ITU-T G.671] Recommendation ITU-T G.671 (2012), *Transmission characteristics of optical components and subsystems*.
+- [b-ITU-T J.160] Recommendation ITU-T J.160 (2005), *Architectural framework for the delivery of time-critical services over cable television networks using cable modems*.
+- [b-ITU-T J.191] Recommendation ITU-T J.191 (2004), *IP feature package to enhance cable modems*.
+- [b-ITU-T Q.1742.1] Recommendation ITU-T Q.1742.1 (2002), *IMT-2000 references to ANSI-41 evolved core network with cdma2000 access network*.
+- [b-ITU-T Y.1222] Recommendation ITU-T Y.1222 (2007), *Traffic control and congestion control in Ethernet-based networks*.
+- [b-ITU-R P.525-2] Recommendation ITU-R P.525-2 (1994), *Calculation of free-space attenuation*.
+- [b-ITU-R P.528-3] Recommendation ITU-R P.528-3 (2012), *Propagation curves for aeronautical mobile and radionavigation services using the VHF, UHF and SHF bands*.
+- [b-ITU-R P.1238-8] Recommendation ITU-R P.1238-8 (2015), *Propagation data and prediction methods for the planning of indoor radiocommunication systems and radio local area networks in the frequency range 300 MHz to 100 GHz*.
+
+
+
+
+
+## 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                                                                                                                       |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b>                                                        |
+| 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
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+
+
+![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
+
+**J.2**
+
+(09/99)
+
+SERIES J: TRANSMISSION OF TELEVISION, SOUND  
+PROGRAMME AND OTHER MULTIMEDIA SIGNALS
+
+General Recommendations
+
+---
+
+**Guidelines on the use of some  
+ITU-T Recommendations in the J series**
+
+ITU-T Recommendation J.2
+
+(Previously CCITT Recommendation)
+
+---
+
+# ITU-T J-SERIES RECOMMENDATIONS
+
+## **TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS**
+
+| <b>General Recommendations</b>                                                                  | <b>J.1–J.9</b> |
+|-------------------------------------------------------------------------------------------------|----------------|
+| General specifications for analogue sound-programme transmission                                | J.10–J.19      |
+| Performance characteristics of analogue sound-programme circuits                                | J.20–J.29      |
+| Equipment and lines used for analogue sound-programme circuits                                  | J.30–J.39      |
+| Digital encoders for analogue sound-programme signals                                           | J.40–J.49      |
+| Digital transmission of sound-programme signals                                                 | J.50–J.59      |
+| Circuits for analogue television transmission                                                   | J.60–J.69      |
+| Analogue television transmission over metallic lines and interconnection with radio-relay links | J.70–J.79      |
+| Digital transmission of television signals                                                      | J.80–J.89      |
+| Ancillary digital services for television transmission                                          | J.90–J.99      |
+| Operational requirements and methods for television transmission                                | J.100–J.109    |
+| Interactive systems for digital television distribution                                         | J.110–J.129    |
+| Transport of MPEG-2 signals on packetised networks                                              | J.130–J.139    |
+| Measurement of the quality of service                                                           | J.140–J.149    |
+| Digital television distribution through local subscriber networks                               | J.150–J.159    |
+
+*For further details, please refer to ITU-T List of Recommendations.*
+
+## **ITU-T RECOMMENDATION J.2**
+
+## **GUIDELINES ON THE USE OF SOME ITU-T RECOMMENDATIONS IN THE J SERIES**
+
+### **Summary**
+
+This Recommendation is intended to provide guidance on the application of ITU-T Recommendations in the J series, in order that the reader may more readily identify those Recommendations that he should consult to obtain detailed information on the technical aspects of his specific interest.
+
+### **Source**
+
+ITU-T Recommendation J.2 was revised by ITU-T Study Group 9 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on 16 September 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 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
+
+|                                                                        | <i>Page</i> |
+|------------------------------------------------------------------------|-------------|
+| 1 Scope .....                                                          | 1           |
+| 2 References .....                                                     | 1           |
+| 3 Guidelines on the use of ITU-T Recommendations in the J series ..... | 1           |
+
+
+
+## **GUIDELINES ON THE USE OF SOME ITU-T RECOMMENDATIONS IN THE J SERIES**
+
+*(revised in 1999)*
+
+## **1 Scope**
+
+This Recommendation is intended to provide guidance on the application of ITU-T Recommendations in the J series, in order that the reader may more readily identify those Recommendations that he should consult to obtain detailed information on the technical aspects of his specific interest.
+
+## **2 References**
+
+The lists of those Recommendations in the J series that are covered in the present Recommendation, and guidelines on their application, are found in Supplement 5 to the J series of Recommendations; the lists give the number, the month and year of adoption, and the title for each Recommendation discussed.
+
+## **3 Guidelines on the use of ITU-T Recommendations in the J series**
+
+It is recommended that, in order to more readily identify the Recommendations in the J series that may be of his specific interest, the reader should consult the guidelines available at the ITU-T website.
+
+The same guidelines also appear in the form of Supplement 5 to the J series of Recommendations.
+
+
+
+## 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                                                                                            |
+| <b>Series J</b> | <b>Transmission of television, sound programme and other multimedia signals</b>                                                |
+| 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                                                           |
\ No newline at end of file
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.203**
+
+(06/2008)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Application for Interactive Digital Television
+
+---
+
+**Common core for digital video recorder platform**
+
+Recommendation ITU-T J.203
+
+
+
+# **Recommendation ITU-T J.203**
+
+## **Common core for digital video recorder platform**
+
+# **Summary**
+
+Recommendation ITU-T J.203 defines the APIs, semantic guarantees and system aspects of a harmonized digital video recorder platform.
+
+## **Source**
+
+Recommendation ITU-T J.203 was approved on 13 June 2008 by ITU-T Study Group 9 (2005-2008) under 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 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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    |
+| 2.1 Normative References .....                               | 1    |
+| 2.2 Informative References .....                             | 1    |
+| 3 Definitions .....                                          | 2    |
+| 4 Abbreviations.....                                         | 2    |
+| 5 Conventions .....                                          | 2    |
+| 6 Common platform definition of Digital Video Recorders..... | 2    |
+| Annex A – DVR/PVR Common Core APIs .....                     | 3    |
+| Appendix I – OCAP additional APIs.....                       | 4    |
+| Appendix II – MHP additional APIs .....                      | 5    |
+| Appendix III – Summary of API Changes.....                   | 6    |
+
+# **Introduction**
+
+This Recommendation is intended to harmonize an application environment for the digital video recorder extension to Recommendation ITU-T J.202.
+
+This work was carried out as a joint effort between DVB and CableLabs.
+
+# Recommendation ITU-T J.203
+
+## Common core for digital video recorder platform
+
+# 1 Scope
+
+The 2006 edition of Recommendation ITU-T J.203, Common core for digital video recorder platform was based on the work of the DVB and Cablelabs and was published as an informative document by the DVB. Since that time, ETSI has published a revised and updated version [1]. This Recommendation revises Recommendation ITU-T J.203 to align with [1].
+
+This Recommendation defines a modular extension to Recommendation ITU-T J.202, and updated as GEM [1], which defines how the recording and playback of digital video (and audio) content is integrated with the GEM [1] platform. This Recommendation is firstly intended to be used by entities writing terminal specifications and/or standards that extend a GEM [1] terminal specification with digital video (and audio) recording and playback. Secondly, it is intended for developers of GEM [1] applications that wish to use digital video (and audio) recording and playback. Implementers should consult the publisher of specifications which reference GEM [1] regarding conformance.
+
+NOTE 1 – This Recommendation defines the interfaces visible to applications. Application developers should not assume that any related interface is available unless it is specifically listed. Terminal standards or implementations may have other interfaces present. One of the primary goals of this Recommendation is to maximize the common aspects concerning the integration of digital video/audio recording between MHP [3] and the various GEM [1] terminal specifications.
+
+NOTE 2 – The structure and content of this Recommendation have been organized for ease of use by those familiar with the original source material; as such, the usual style of ITU-T Recommendations has not been applied.
+
+# 2 References
+
+## 2.1 Normative 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 published regularly. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [1] ETSI TS 102 817 V1.1.1 (2007-09), *Digital Video Broadcasting (DVB); Digital Recording Extension to Globally Executable Multimedia Home Platform (GEM)*.  
+([http://webapp.etsi.org/exchangefolder/ts\\_102817v010101p.pdf](http://webapp.etsi.org/exchangefolder/ts_102817v010101p.pdf))  
+([http://webapp.etsi.org/exchangefolder/ts\\_102817v010101p0.zip](http://webapp.etsi.org/exchangefolder/ts_102817v010101p0.zip))
+
+## 2.2 Informative references
+
+- [2] OC-SP-OCAP-DVR-I03-070509 (2007), *OCAP DVR Extension*.  
+(<http://www.opencable.com/specifications/ocap.html>)
+- [3] ETSI TS 102 816 V1.1.1 (2007-09), *Digital Video Broadcasting (DVB); Personal Video Recorder (PVR)/Personal Data Recorder (PDR) Extension to the Multimedia Home Platform*.  
+([http://webapp.etsi.org/exchangefolder/ts\\_102816v010101p.pdf](http://webapp.etsi.org/exchangefolder/ts_102816v010101p.pdf))  
+([http://webapp.etsi.org/exchangefolder/ts\\_102816v010101p0.zip](http://webapp.etsi.org/exchangefolder/ts_102816v010101p0.zip))
+
+# **3 Definitions**
+
+This Recommendation defines the following term:
+
+**3.1 synthesized timeline:** A timeline for a piece of content which was synthesized by the GEM recording terminal (as opposed to being included as part of the piece of content when it was transmitted).
+
+# **4 Abbreviations**
+
+This Recommendation uses the abbreviations given in clause 3 of [1].
+
+# **5 Conventions**
+
+This Recommendation includes the conventions of clause 4 in [1].
+
+# **6 Common platform definition of Digital Video Recorders**
+
+It is recommended to use [1] for common core for digital video recorder platform. The recommended platform definitions for the common core are defined in Annex A. Regional extensions are presented in Appendices I and II. Appendix III summarizes changes to the platform definitions presented in this Recommendation.
+
+# **Annex A**
+
+## **DVR/PVR Common Core APIs**
+
+(This annex forms an integral part of this Recommendation)
+
+The following APIs are defined by ETSI [1] and form the content of this annex.
+
+org.ocap.shared.dvr
+
+org.ocap.shared.dvr.navigation
+
+org.ocap.shared.media
+
+# **Appendix I**
+
+## **OCAP additional APIs**
+
+(This appendix does not form an integral part of this Recommendation)
+
+The following APIs are defined by OCAP [2] and form the content of this appendix.
+
+org.ocap.dvr
+
+org.ocap.dvr.event
+
+org.ocap.dvr.storage
+
+# **Appendix II**
+
+## **MHP additional APIs**
+
+(This appendix does not form an integral part of this Recommendation)
+
+The following APIs are defined by ETSI [3] and form the content of this appendix.
+
+org.dvb.pvr
+
+org.dvb.pvr.navigation
+
+# Appendix III
+
+## Summary of API changes
+
+(This appendix does not form an integral part of this Recommendation)
+
+- 1) Addition of two new states in org.ocap.shared.dvr.LeafRecording Request
+- 2) Modification of org.ocap.shared.dvr.LeafRecording Request.getService()
+- 3) Modification of some of the semantics of org.ocap.shared.dvr.LocatorRecordingSpec
+- 4) Modification of some of the semantics of org.ocap.shared.dvr.navigation.RecordingList
+- 5) Addition of org.ocap.shared.dvr.navigation.getCascadingFilter() method
+- 6) Modification of some of the semantics of org.ocap.shared.dvr.navigation.RecordingListIterator
+- 7) Modification of some of the semantics of org.ocap.shared.dvr.ParentRecordingRequest
+- 8) Modification of some of the semantics of org.ocap.shared.dvr.RecordedService
+- 9) Addition of new constructor to org.ocap.shared.dvr.RecordingChangeEvent and modification of some of the semantics
+- 10) Addition of new exceptions to org.ocap.shared.dvr.RecordingFailedException and modification of some of the semantics
+- 11) Modification of some of the semantics of org.ocap.shared.dvr.RecordingManager
+- 12) Modification of inheritance to org.ocap.shared.dvr.RecordingPermission and removal of a method
+- 13) Modification of some of the semantics of org.ocap.shared.dvr.RecordingRequest
+- 14) Modification of some of the semantics of org.ocap.shared.dvr.RecordingTerminatedEvent and correction of javadoc error
+- 15) Add org.ocap.shared.dvr.SegmentedRecordedService
+- 16) Modification of some of the semantics of org.ocap.shared.dvr.ServiceContextRecordingSpec
+- 17) Modification of some of the semantics of org.ocap.shared.dvr.ServiceRecordingSpec
+- 18) Modification of some of the semantics of org.ocap.shared.media.BeginningContentEvent
+- 19) Modification of some of the semantics of org.ocap.shared.media.EndOfContentEvent
+- 20) Add org.ocap.shared.dvr.media.FrameControl
+- 21) Modification of some of the semantics of org.ocap.shared.media.MediaTimeFactoryControl
+- 22) Modification of some of the semantics of org.ocap.shared.media.TimeLine
+- 23) Modification of some of the semantics of org.ocap.shared.media.TimeShiftControl
+
+
+
+# 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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/J/T-REC-J.204-200806-I_PDF-E/raw.md b/marked/J/T-REC-J.204-200806-I_PDF-E/raw.md
new file mode 100644
index 0000000000000000000000000000000000000000..809f7b2ad7473eccba143d4286fe3a20e544bddd
--- /dev/null
+++ b/marked/J/T-REC-J.204-200806-I_PDF-E/raw.md
@@ -0,0 +1,1107 @@
+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.204**
+
+(06/2008)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Application for Interactive Digital Television
+
+# --- **Metrics gathering specification**
+
+Recommendation ITU-T J.204
+
+![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) features a globe with a red lightning bolt striking it, symbolizing global communication. To the right of the globe, the text "International Telecommunication Union" is written in a blue, sans-serif font.
+
+ITU logo
+
+
+
+## **Recommendation ITU-T J.204**
+
+# **Metrics gathering specification**
+
+## **Summary**
+
+Recommendation ITU-T J.204 defines a data format and transmission protocol for the collection of service delivery metrics on customer premises equipment, such as digital cable set top boxes
+
+###### **Source**
+
+Recommendation ITU-T J.204 was approved on 13 June 2008 by ITU-T Study Group 9 (2005-2008) under 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 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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  |
+| 1.1  | Introduction and Purpose.....                   | 1  |
+| 2    | References.....                                 | 1  |
+| 2.1  | Normative References .....                      | 1  |
+| 2.2  | Informative References .....                    | 1  |
+| 3    | Terms and Definitions .....                     | 2  |
+| 4    | Abbreviations and acronyms .....                | 2  |
+| 5    | Overview .....                                  | 2  |
+| 5.1  | General Context.....                            | 2  |
+| 6    | Metrics Requirements.....                       | 3  |
+| 6.1  | Transmission Protocol.....                      | 3  |
+| 6.2  | Data Model .....                                | 5  |
+|      | Annex A – Metrics Data Model Schema .....       | 7  |
+|      | Annex B – Schema Data Element Requirements..... | 16 |
+| B.1  | protocolVersionMajor .....                      | 16 |
+| B.2  | protocolVersionMinor .....                      | 16 |
+| B.3  | hostID .....                                    | 16 |
+| B.4  | hostType .....                                  | 16 |
+| B.5  | createTime .....                                | 16 |
+| B.6  | transmitTime.....                               | 16 |
+| B.7  | privateData .....                               | 16 |
+| B.8  | serviceSelection.....                           | 16 |
+| B.9  | tuning.....                                     | 17 |
+| B.10 | SDV .....                                       | 17 |
+| B.11 | servicePresentation .....                       | 17 |
+| B.12 | segmentPresentation .....                       | 17 |
+| B.13 | DPI.....                                        | 17 |
+| B.14 | inputEvent.....                                 | 18 |
+| B.15 | applicationLoadRequested .....                  | 18 |
+| B.16 | applicationLoaded .....                         | 18 |
+| B.17 | applicationLifecycle .....                      | 18 |
+| B.18 | environmentSelection .....                      | 18 |
+| B.19 | applicationMode .....                           | 19 |
+| B.20 | application .....                               | 19 |
+
+
+
+# Metrics gathering specification
+
+# 1 Scope
+
+This Recommendation defines a data format and transmission protocol for the collection of service delivery metrics on customer premises equipment, such as digital cable set top boxes. Metrics are records generated by relevant service delivery events, such as a service selection event. Each metrics record includes a timestamp of the event. This technology provides a means to accurately and efficiently collect metrics for the purpose of measuring service delivery.
+
+NOTE – The structure and content of this Recommendation have been organized for ease of use by those familiar with the original source material; as such, the usual style of ITU-T Recommendations has not been applied.
+
+## 1.1 Introduction and Purpose
+
+The purpose of this Recommendation is to specify metrics collection and transmission mechanisms and interfaces on receiver platforms. The data formats and transmission protocols may also be adopted by proprietary systems.
+
+For the purposes of this Recommendation, the term "metrics" refers to specific data, defined herein, that is generated by a receiver and transmitted to a cable headend.
+
+Metrics, as defined in this Recommendation, are intended to complement other measurement systems that may be employed by cable operators.
+
+# 2 References
+
+## 2.1 Normative 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.
+
+- [ATIS] Usage Data Management For Packet-Based Services – Service-Neutral Protocol Specification For Billing Applications, ATIS-0300075.1.2006, August 2006.  
+<https://www.atis.org/docstore/product.aspx?id=22606>
+- [IPDR/SP] IPDR/SP Protocol Specification Version 2.2, August 25, 2006.  
+<http://www.ipdr.org/public/DocumentMap/SP2.2.pdf>
+- [IPDR/XDR] IPDR/XDR File Encoding Format, Version 3.5.1, November 2004.  
+<http://www.ipdr.org/public/DocumentMap/XDR3.5.1.pdf>
+
+## 2.2 Informative References
+
+- [OCAP 1.1] OpenCable Applications Platform, Profile 1.1, OC-SP-OCAP1.1-I01-061229, December 29, 2006, Cable Television Laboratories, Inc.  
+<http://www.opencable.com/downloads/specs/OC-SP-OCAP1.1-I01-061229.pdf>
+- [ETV] Enhanced TV Binary Interchange Format, OC-SP-ETV-BIF1.0-I04-070921, September 21, 2007, Cable Television Laboratories, Inc.  
+<http://www.cablelabs.com/specifications/OC-SP-ETV-BIF1.0-I04-070921.pdf>
+
+# 3 Terms and Definitions
+
+This Recommendation defines the following terms:
+
+- 3.1 authorized collector:** An Event Tracking API-compliant server that implements the receiving side of the IPDR Streaming Protocol, and which has been authorized to participate in the overall Collection System.
+- 3.2 data message:** A message transmitted between an IPDR Exporter and Collector across the Streaming Protocol, containing a common Streaming Protocol header and an optional payload consisting of control and Data Records.
+- 3.3 data record:** The binary encoding of an IPDR record.
+- 3.4 Internet Protocol Detail Record (IPDR):** The fundamental unit of data transferred between an Exporter and a Collector. It is defined by a Template and contains Fields.
+- 3.5 IPDR-Type:** A constraint on the value and format of an individual Field within a Data Record; e.g., dateTime.
+- 3.6 Internet Protocol Detail Record/Streaming Protocol (IPDR/SP):** The protocol used to transfer Data Messages and Data Records between Exporter and Collectors.
+- 3.7 IPDR/SP collector functionality:** An implementation on the data-receiving side of the IPDR/SP. It enables the reception and collection of Data Records from IPDR/SP Exporters. It is typically part of an OSS/BSS, or a mediation system.
+- 3.8 IPDR/SP exporter functionality:** An implementation on the data-producing side of the IPDR/SP. It enables formatting and sending of Data Records to an interested consumer system, e.g., at a cable headend using the IPDR/SP.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations:
+
+|         |                                                    |
+|---------|----------------------------------------------------|
+| CPE     | Customer Premises Equipment                        |
+| IPDR    | Internet Protocol Detail Record                    |
+| IPDR/SP | Internet Protocol Detail Record Streaming Protocol |
+
+# 5 Overview
+
+## 5.1 General Context
+
+Metrics are a set of well-defined data that are reported to a cable network by a receiver, for the purpose of measuring certain aspects of cable service delivery. This Recommendation specifies a data model and transmission protocol. Platforms that support this Recommendation are expected to define the semantics for the data points that are syntactically defined herein.
+
+The means for metrics collection on the receiver is composed of a log, which contains log records. A log and log records are created and stored in a format determined by an implementer. Log records are created by the receiver in response to well-defined events, such as operations performed by a receiver on behalf of applications, or generated directly by applications. A log and its log records are transmitted from the receiver in a well-known format, under control of logic implemented by the network operator.
+
+There are three logical metrics components: a so-called "metrics engine" implemented within a receiver; one or more privileged applications that configure and manage the metrics engine, collectively called the "metrics controller"; and any other "metrics logging" applications that interface with the metrics engine to generate application-specific log records.
+
+This Recommendation defines requirements for a metrics engine and the interface between a metrics engine and a cable headend. Metrics data is considered private to the cable network. Functions such as storage, aggregation, and reporting are the responsibility of a network operator. This interface provides a well-known data format and protocol to ensure that metrics are comparable across cable networks.
+
+The metrics engine is a component of the system software that includes the operating system and middleware, such as OCAP that communicates with the controller and logging applications as well as the cable headend (see Transmission Protocol clause below). The middleware (e.g., OCAP), is a logical software layer between the operating system and the applications that abstracts the functionality of the hardware and other functions and provides an interoperable application programming interface layer.
+
+The controller application informs the metrics engine which metrics data are of interest
+
+![Figure 1 – Logical Model of Metrics System. The diagram shows a CPE (Customer Premises Equipment) box containing a 'Controller application' and 'Logging applications'. These applications are connected via a 'Middleware API' to 'System software' which contains a 'Metrics engine'. The 'Metrics engine' is connected to an 'IPDR collector' via an 'IPDR/SP' protocol. The diagram is labeled J.204(08)_F01.](7a0db9703b68b3d06cdaeefc084c0006_img.jpg)
+
+```
+graph TD
+    subgraph CPE
+        CA[Controller application]
+        LA[Logging applications]
+        SS[System software]
+        ME[Metrics engine]
+        CA <--> SS
+        LA <--> SS
+    end
+    IPDR[IPDR collector] <--> |IPDR/SP| ME
+    CA <--> |Middleware API| SS
+```
+
+Figure 1 – Logical Model of Metrics System. The diagram shows a CPE (Customer Premises Equipment) box containing a 'Controller application' and 'Logging applications'. These applications are connected via a 'Middleware API' to 'System software' which contains a 'Metrics engine'. The 'Metrics engine' is connected to an 'IPDR collector' via an 'IPDR/SP' protocol. The diagram is labeled J.204(08)\_F01.
+
+**Figure 1 – Logical Model of Metrics System**
+
+Interfaces between metrics controller and logging applications and the metric engine are currently not defined within this Recommendation. We expect to include definition of a Java API for this purpose in a subsequent revision to this Recommendation.
+
+The metrics engine incorporates IPDR/SP Exporter functionality. A cable headend that supports metrics implements IPDR/SP Collector functionality. See <https://www.atis.org/docstore/product.aspx?id=22606>
+
+[IPDR/SP] for details.
+
+# 6 Metrics Requirements
+
+This clause defines requirements for metrics and the interface between a metrics engine and a cable headend.
+
+## 6.1 Transmission Protocol
+
+IPDR/SP is the protocol for transmitting metrics data to a cable headend. It is an American National Standard ATIS-0300075.1.2006 [ATIS]. The IPDR/SP utilizes a light-weight, session-oriented, real-time streaming protocol to quickly and reliably deliver metrics data, a.k.a. IPDRs, from an "Exporter" to a "Collector" (typically a type of mediation system). Receivers that support this
+
+metrics Recommendation SHALL implement IPDR/SP Exporter functionality. For brevity, the term "metrics engine" is to be understood to include IPDR/SP Exporter functionality. The "Collector" is an implementation on the data receiving side of the IPDR/SP and is typically part of a back-office system.
+
+The IPDR/SP utilizes a slightly augmented version of the XDR protocol, described in IETF RFC 1832, to encode IPDRs. IPDR/SP uses many of the primitive types defined by the IETF XDR protocol to encode as much information as possible in a compact binary representation.
+
+The IPDR/SP uses TCP as its transport layer protocol. The transport layer acknowledgements are used to ensure the reliable delivery of data packets and detection of lost Exporters. In addition, IPDR/SP allows another level of application reliability as described below.
+
+### 6.1.1 IPDR/SP Templates
+
+The IPDR/SP uses a highly-efficient encoding scheme, where only the values for each field of a particular type of IPDR are encapsulated and sent in a Data Message from the Exporter to the Collector. The field names, types, and lengths are not included in the IPDRs; instead, the field names, types, and lengths are specified indirectly by referring to a session-specific Template that describes contents of that type of IPDR.
+
+Within the IPDR/SP, IPDRs are always exchanged within the context of a particular session that exists between a particular Exporter and a particular Collector. During the session establishment phase, the Exporter provides the Collector with a list of Templates, where each Template describes the layout of a particular type of Data Record (a Data Record is a binary encoding of an IPDR record) that can be sent to the Collector. Data Records are always packaged into a Data Message before being sent to the Collector.
+
+Each Template definition contains a TemplateID, an IPDR-Type name, an explicit reference to the XML Schema which describes the IPDR-Type referred to by the Template, and an ordered list of triplets, where each triplet consists of a field name, field ID, and type. These field names and types must correspond to those defined in the corresponding IPDR Schema for the particular IPDR-Type referred to by the Template.
+
+A particular Template not only specifies an IPDR-Type and corresponding XML Schema, but also specifies the particular subset of fields, and the order in which those fields will be laid out within Data Records referencing that Template. A Template for a particular IPDR-Type does not have to contain all possible fields defined in the XML Schema for that IPDR-Type; it might exclude certain optional or conditional fields. As such, there could be multiple Templates referring to the same IPDR-Type within a particular session.
+
+Typically the Exporter sends a list of supported Templates to the Collector during the Session Establishment phase; however, the IPDR/SP also provides a mechanism whereby a Collector can negotiate with an Exporter regarding the Templates to be used during that session.
+
+Once a session has been established, Data Messages are sent from the Exporter to the Collector. Each Data Message contains a sequence number, a TemplateID, which points to the particular Template that describes the contents of the Data Record contained within this particular Data Message, followed by a Data Record (a binary-encoded IPDR). An active session can simultaneously support many different IPDR-Types and many different subsets of fields for a particular IPDR-Type.
+
+The use of Templates makes it possible for Exporters to deliver only the actual data values for each usage event without having to include any data descriptors in each Data Record. This significantly reduces the volume of information sent over communication links. The use of Templates also has the added advantage of enabling Data Records to contain only a pertinent subset of all fields for a particular IPDR-Type, thereby reducing the number of "empty" fields. This also reduces the volume of information sent over communication links.
+
+### 6.1.2 System level reliability
+
+During Session Establishment, the Exporter and the Collector agree on how often the Collector will send a Data Acknowledge Message back to the Exporter. Each Data Acknowledge Message refers to the sequence number of the most recently received and stored Data Message. By sending a Data Acknowledge Message, the Collector tells the Exporter that all Data Messages with sequence numbers less than or equal to the sequence number contained within the Data Acknowledge Message have been received and transferred to some type of persistent storage.
+
+Once the Collector has acknowledged receipt of a particular Data Message, the Exporter no longer needs to maintain the Data Record contained within that Data Message. If the Collector goes down, or if the connection between the Exporter and Collector is disrupted, the Exporter can compare its most recently generated Data Message sequence number with the last acknowledged sequence number to know which Data Messages and Data Records it needs to preserve and either resend to the Collector or send to alternate Collectors. The Exporter can continue to stream new Data Messages to a Collector, regardless of whether previous Data Messages have been acknowledged, as long as the Collector sends intermittent Data Acknowledge Messages at the frequency agreed to at the start of the session.
+
+A metrics engine SHALL adhere to the following requirements:
+
+- The metrics engine SHALL NOT attempt to connect to an unauthorized Collector.
+- The metrics engine SHALL NOT generate data elements unless connected to and configured to by an authorized Collector.
+
+This Recommendation does not place requirements on Collectors. The following guidelines may be used by cable operators in order to support metrics collection.
+
+- The Collectors SHOULD implement the IPDR/SP Collector functionality.
+- One or more redundant Collectors SHOULD be configured such that there MAY be more than one Collector connected to one Exporter. This configuration provides high availability and improved robustness of the collection system.
+
+## 6.2 Data Model
+
+Within the IPDR/SP, every IPDR refers to its particular IPDR-Type (or type of event message), which then defines the contents that an IPDR of that IPDR-Type is expected to contain. IPDR/SP requires that all IPDR-Types be specified using the XML schema language. Defining event messages within IPDR/SP is a relatively easy and straightforward process.
+
+[IPDR/SSDG] defines a human readable format for defining a generic data model, as an XML Schema. Annex A defines a data model for metrics using this format. Receivers that support metrics SHALL implement the data model defined in Annex A.
+
+The XML schema defining a particular IPDR-Type SHALL contain the type-name for that IPDR-Type and a list of all possible fields that MAY appear within an IPDR of that type. Each field has a name, type, and an attribute specifying whether that field is required, optional, or conditional. Additionally, each field MAY be annotated with supplemental textual information, explaining the nature of the data contained in that field.
+
+The IPDR/SP gives implementers nearly complete freedom to define the fields that are contained within a particular IPDR-Type.
+
+XML schema provides an easy way for cable operators and vendors to add their own extensions to the base event message types defined in this Recommendation. Extensions MAY be added simply by creating a new XML schema, defining a new IPDR-Type name, importing fields from pre-existing "standard" IPDR-Types, and then adding definitions only for any new implementation-specific fields.
+
+Since XML schema supports namespaces, there is a built-in mechanism for reducing the chances of field name collision, especially when using implementation-specific extensions, by placing implementation-specific fields into their own unique namespace. The "ipdr" namespace, which contains all of the IPDR defined fields, is managed by IPDR.org. Other entities are free to create their own namespaces, and place their fields within their own unique namespaces.
+
+IPDR/SP defines a mechanism for transforming the XML human readable data model into a binary format optimized for on-the-wire transmission, via XDR. As part of their requirement to implement an IPDR/SP Exporter, receivers that support metrics SHALL be able to transmit a binary representation of the data model defined in Annex A.
+
+Since XML schema is used to describe the contents of IPDRs, it is a simple exercise to translate an XDR encoded IPDR to an XML encoding, and vice versa. While it would be undesirable to send XML-encoded IPDRs over a high-traffic connection, once the IPDRs have arrived at a Collector there are circumstances where being able to translate those IPDRs from XDR to XML can be quite helpful for debugging, human readability, or translation to other encoding schemes.
+
+# Annex A
+
+## Metrics Data Model Schema
+
+(This annex forms an integral part of this Recommendation)
+
+```
+<?xml version="1.0" encoding="UTF-8"?>
+
+<schema xmlns="http://www.w3.org/2001/XMLSchema"
+  xmlns:OCAP="http://www.ipdr.org/namespaces/CableLabs(R)/OCAP(TM) "
+  xmlns:ipdr="http://www.ipdr.org/namespaces/ipdr"
+  targetNamespace="http://www.ipdr.org/namespaces/CableLabs(R)/OCAP(TM) " version="3.5-A.0"
+  elementFormDefault="qualified" attributeFormDefault="unqualified">
+  <import namespace="http://www.ipdr.org/namespaces/ipdr"
+    schemaLocation="http://www.ipdr.org/public/IPDRDoc3.5.1.xsd"/>
+  <include schemaLocation="http://www.ipdr.org/public/IPDRTypes.xsd"/>
+
+  <element name="protocolVersionMajor" type="byte">
+  </element>
+
+  <element name="protocolVersionMinor" type="byte">
+  </element>
+
+  <element name="hostID" type="string"/>
+
+  <element name="hostType">
+    <simpleType>
+      <restriction base="int">
+        <enumeration value="1">
+          <annotation>
+            <appinfo>
+              <ipdr:enumMeaning>
+                OCAP
+              </ipdr:enumMeaning>
+            </appinfo>
+          </annotation>
+        </enumeration>
+        <enumeration value="2">
+          <annotation>
+            <appinfo>
+              <ipdr:enumMeaning>
+                ETV
+              </ipdr:enumMeaning>
+            </appinfo>
+          </annotation>
+        </enumeration>
+        <enumeration value="3">
+          <annotation>
+            <appinfo>
+              <ipdr:enumMeaning>
+                other
+              </ipdr:enumMeaning>
+            </appinfo>
+          </annotation>
+        </enumeration>
+      </restriction>
+    </simpleType>
+  </element>
+
+  <element name="createTime" type="ipdr:dateTimeMsec">
+  </element>
+
+  <element name="transmitTime" type="ipdr:dateTimeMsec">
+  </element>
+
+  <element name="privateData" type="hexBinary">
+  </element>
+```
+
+```
+
+<element name="serviceSelection">
+  <complexType>
+    <sequence>
+      <element ref="createTime"/>
+      <element name="sourceID" type="int">
+      </element>
+    </sequence>
+  </complexType>
+</element>
+
+<element name="tuning">
+  <complexType>
+    <sequence>
+      <element ref="createTime"/>
+      <element name="tunerID" type="int">
+      </element>
+      <element name="frequency" type="int">
+      </element>
+      <element name="programNumber" type="int">
+      </element>
+    </sequence>
+  </complexType>
+</element>
+
+<element name="SDV">
+  <complexType>
+    <sequence>
+      <element ref="createTime"/>
+      <element name="sourceID" type="int">
+      </element>
+    </sequence>
+  </complexType>
+</element>
+
+<element name="servicePresentation">
+  <complexType>
+    <sequence>
+      <element ref="createTime"/>
+      <element name="sourceID" type="int">
+      </element>
+      <element name="aspectRatio">
+        <simpleType>
+          <restriction base="int">
+            <enumeration value="1">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    4:3
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+            <enumeration value="2">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    16:9
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+          </restriction>
+        </simpleType>
+      </element>
+      <element name="resolution" type="int">
+      </element>
+      <element name="audio">
+        <simpleType>
+          <restriction base="int">
+            <enumeration value="0">
+
+```
+
+```
+
+        <annotation>
+          <appinfo>
+            <ipdr:enumMeaning>
+              No audio
+            </ipdr:enumMeaning>
+          </appinfo>
+        </annotation>
+      </enumeration>
+      <enumeration value="1">
+        <annotation>
+          <appinfo>
+            <ipdr:enumMeaning>
+              Audio
+            </ipdr:enumMeaning>
+          </appinfo>
+        </annotation>
+      </enumeration>
+    </restriction>
+  </simpleType>
+</element>
+</sequence>
+</complexType>
+</element>
+
+<element name="segmentPresentation">
+  <complexType>
+    <sequence>
+      <element ref="createTime"/>
+      <element name="segmentID" type="int">
+      </element>
+    </sequence>
+  </complexType>
+</element>
+
+<element name="DPI">
+  <complexType>
+    <sequence>
+      <element ref="createTime"/>
+      <element name="sourceID" type="int">
+      </element>
+      <element name="replacementID" type="int">
+      </element>
+      <element name="replacementSource">
+        <simpleType>
+          <restriction base="int">
+            <enumeration value="1">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    In transport
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+            <enumeration value="2">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    Out of transport
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+            <enumeration value="3">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    From Memory
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+          </restriction>
+        </simpleType>
+      </element>
+    </sequence>
+  </complexType>
+</element>
+
+```
+
+```
+
+    </enumeration>
+  </restriction>
+</simpleType>
+</element>
+<element name="switchLevel" type="int">
+  <simpleType>
+    <restriction base="int">
+      <enumeration value="0">
+        <annotation>
+          <appinfo>
+            <ipdr:enumMeaning>
+              L0
+            </ipdr:enumMeaning>
+          </appinfo>
+        </annotation>
+      </enumeration>
+      <enumeration value="1">
+        <annotation>
+          <appinfo>
+            <ipdr:enumMeaning>
+              L1
+            </ipdr:enumMeaning>
+          </appinfo>
+        </annotation>
+      </enumeration>
+    </restriction>
+  </simpleType>
+</element>
+</sequence>
+</complexType>
+</element>
+
+<element name="inputEvent">
+  <complexType>
+    <sequence>
+      <element ref="createTime"/>
+      <element name="keyCode" type="int">
+      </element>
+    </sequence>
+  </complexType>
+</element>
+
+<element name="applicationLoadRequested">
+  <complexType>
+    <sequence>
+      <element ref="createTime"/>
+      <element name="appID" type="int">
+      </element>
+      <element name="appType">
+        <simpleType>
+          <restriction base="int">
+            <enumeration value="1">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    OCAP
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+            <enumeration value="2">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    ETV
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+            <enumeration value="3">
+              <annotation>
+
+```
+
+```
+
+        <appinfo>
+          <ipdr:enumMeaning>
+            other
+          </ipdr:enumMeaning>
+        </appinfo>
+      </annotation>
+    </enumeration>
+  </restriction>
+</simpleType>
+</element>
+</sequence>
+</complexType>
+</element>
+
+<element name="applicationLoaded">
+  <complexType>
+    <sequence>
+      <element ref="createTime"/>
+      <element name="appID" type="int">
+      </element>
+      <element name="appType">
+        <simpleType>
+          <restriction base="int">
+            <enumeration value="1">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    OCAP
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+            <enumeration value="2">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    ETV
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+            <enumeration value="3">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    other
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+          </restriction>
+        </simpleType>
+      </element>
+      <element name="numResourceFiles" type="int">
+      </element>
+      <element name="transportProtocol">
+        <simpleType>
+          <restriction base="int">
+            <enumeration value="1">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    IBOC
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+            <enumeration value="2">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+
+```
+
+```
+
+        OOB0C
+      </ipdr:enumMeaning>
+    </appinfo>
+  </annotation>
+</enumeration>
+<enumeration value="3">
+  <annotation>
+    <appinfo>
+      <ipdr:enumMeaning>
+        HTTP
+      </ipdr:enumMeaning>
+    </appinfo>
+  </annotation>
+</enumeration>
+</restriction>
+</simpleType>
+</element>
+<element name="controlCode">
+  <simpleType>
+    <restriction base="int">
+      <enumeration value="1">
+        <annotation>
+          <appinfo>
+            <ipdr:enumMeaning>
+              LOADED
+            </ipdr:enumMeaning>
+          </appinfo>
+        </annotation>
+      </enumeration>
+      <enumeration value="2">
+        <annotation>
+          <appinfo>
+            <ipdr:enumMeaning>
+              PAUSED
+            </ipdr:enumMeaning>
+          </appinfo>
+        </annotation>
+      </enumeration>
+      <enumeration value="3">
+        <annotation>
+          <appinfo>
+            <ipdr:enumMeaning>
+              RUNNING
+            </ipdr:enumMeaning>
+          </appinfo>
+        </annotation>
+      </enumeration>
+    </restriction>
+  </simpleType>
+</element>
+</sequence>
+</complexType>
+</element>
+
+<element name="applicationLifecycle">
+  <complexType>
+    <sequence>
+      <element ref=" createTime"/>
+      <element name="appID" type="int"/>
+      <element name="appType">
+        <simpleType>
+          <restriction base="int">
+            <enumeration value="1">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    OCAP
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+
+```
+
+```
+
+    <enumeration value="2">
+      <annotation>
+        <appinfo>
+          <ipdr:enumMeaning>
+            ETV
+          </ipdr:enumMeaning>
+        </appinfo>
+      </annotation>
+    </enumeration>
+    <enumeration value="3">
+      <annotation>
+        <appinfo>
+          <ipdr:enumMeaning>
+            other
+          </ipdr:enumMeaning>
+        </appinfo>
+      </annotation>
+    </enumeration>
+  </restriction>
+</simpleType>
+</element>
+<element name="lifecycleState">
+  <simpleType>
+    <restriction base="int">
+      <enumeration value="1">
+        <annotation>
+          <appinfo>
+            <ipdr:enumMeaning>
+              LAUNCHED
+            </ipdr:enumMeaning>
+          </appinfo>
+        </annotation>
+      </enumeration>
+      <enumeration value="2">
+        <annotation>
+          <appinfo>
+            <ipdr:enumMeaning>
+              PAUSED
+            </ipdr:enumMeaning>
+          </appinfo>
+        </annotation>
+      </enumeration>
+      <enumeration value="3">
+        <annotation>
+          <appinfo>
+            <ipdr:enumMeaning>
+              RESUMED
+            </ipdr:enumMeaning>
+          </appinfo>
+        </annotation>
+      </enumeration>
+      <enumeration value="4">
+        <annotation>
+          <appinfo>
+            <ipdr:enumMeaning>
+              TERMINATED
+            </ipdr:enumMeaning>
+          </appinfo>
+        </annotation>
+      </enumeration>
+    </restriction>
+  </simpleType>
+</element>
+</sequence>
+</complexType>
+</element>
+
+<element name="environmentSelection">
+  <complexType>
+    <sequence>
+      <element ref="createTime"/>
+    
+```
+
+```
+
+<element name="environment">
+  <simpleType>
+    <restriction base="int">
+      <enumeration value="1">
+        <annotation>
+          <appinfo>
+            <ipdr:enumMeaning>
+              Cable
+            </ipdr:enumMeaning>
+          </appinfo>
+        </annotation>
+      </enumeration>
+      <enumeration value="2">
+        <annotation>
+          <appinfo>
+            <ipdr:enumMeaning>
+              Non cable
+            </ipdr:enumMeaning>
+          </appinfo>
+        </annotation>
+      </enumeration>
+    </restriction>
+  </simpleType>
+</element>
+</sequence>
+</complexType>
+</element>
+
+<element name="applicationMode">
+  <complexType>
+    <sequence>
+      <element ref=" createTime"/>
+      <element name="appID" type="int"/>
+      <element name="appType"/>
+      <element name="mode">
+        <simpleType>
+          <restriction base="int">
+            <enumeration value="1">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    CROSS_ENVIRONMENT
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+            <enumeration value="2">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    BACKGROUND
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+            <enumeration value="3">
+              <annotation>
+                <appinfo>
+                  <ipdr:enumMeaning>
+                    NORMAL
+                  </ipdr:enumMeaning>
+                </appinfo>
+              </annotation>
+            </enumeration>
+          </restriction>
+        </simpleType>
+      </element>
+    </sequence>
+  </complexType>
+</element>
+
+```
+
+```
+
+<element name="application">
+  <complexType>
+    <sequence>
+      <element ref="createTime"/>
+      <element name="privateData" type="hexBinary">
+      </element>
+    </sequence>
+  </complexType>
+</element>
+
+<complexType name="OCAP-Type">
+  <complexContent>
+    <extension base="ipdr:IPDRType">
+      <sequence>
+        <element ref="protocolVersionMajor"/>
+        <element ref="protocolVersionMinor"/>
+        <element ref="hostID"/>
+        <element ref="hostType"/>
+        <element ref="createTime"/>
+        <element ref="transmitTime"/>
+        <element ref="privateData"/>
+        <element ref="serviceSelection" minOccurs="0" maxOccurs="unbounded"/>
+        <element ref="tuning" minOccurs="0" maxOccurs="unbounded"/>
+        <element ref="SDV" minOccurs="0" maxOccurs="unbounded"/>
+        <element ref="servicePresentation" minOccurs="0" maxOccurs="unbounded"/>
+        <element ref="segmentPresentation" minOccurs="0" maxOccurs="unbounded"/>
+        <element ref="DPI" minOccurs="0" maxOccurs="unbounded"/>
+        <element ref="inputEvent" minOccurs="0" maxOccurs="unbounded"/>
+        <element ref="applicationLoadRequested" minOccurs="0" maxOccurs="unbounded"/>
+        <element ref="applicationLoaded" minOccurs="0" maxOccurs="unbounded"/>
+        <element ref="applicationLifecycle" minOccurs="0" maxOccurs="unbounded"/>
+        <element ref="environmentSelection" minOccurs="0" maxOccurs="unbounded"/>
+        <element ref="applicationMode" minOccurs="0" maxOccurs="unbounded"/>
+        <element ref="application" minOccurs="0" maxOccurs="unbounded"/>
+      </sequence>
+    </extension>
+  </complexContent>
+</complexType>
+
+</schema>
+
+```
+
+# Annex B
+
+## Schema Data Element Requirements
+
+(This annex forms an integral part of this Recommendation)
+
+This Recommendation may be referenced by [ETV] or other platforms.
+
+Where semantics for the data elements of Annex A may be consistent across all platforms, they are defined in this annex.
+
+Where semantics for the data elements of Annex A are platform specific, a platform definition that includes this data model specification is expected to further define the element. In such cases, Platform Specific Semantics will further define an element.
+
+### **B.1 protocolVersionMajor**
+
+This 8-bit field SHALL indicate the major version of this Recommendation. This field SHALL have the value 1.
+
+### **B.2 protocolVersionMinor**
+
+This 8-bit field SHALL indicate the minor version of this Recommendation. This field SHALL have the value 0.
+
+### **B.3 hostID**
+
+This string field SHALL indicate a unique host identifier. This value SHALL be defined by Platform Specific Semantics.
+
+### **B.4 hostType**
+
+This enumerated integer field SHALL indicate the Host type. This value SHALL be one of: 1 for OCAP, 2 for ETV, or 3 for other, as selected by Platform Specific Semantics.
+
+### **B.5 createTime**
+
+This dateTimeMsec field SHALL indicate when the metrics log was created or last flushed by the platform.
+
+### **B.6 transmitTime**
+
+This dateTimeMsec field SHALL indicate when the metrics log was last transmitted to the headend by the platform.
+
+### **B.7 privateData**
+
+This hexBinary field MAY be generated by the platform for private use.
+
+### **B.8 serviceSelection**
+
+This complex field SHALL indicate the time when a new service has been selected, together with the integer Source ID of that new service.
+
+The *sourceID* value SHALL be defined by Platform Specific Semantics.
+
+### **B.9 tuning**
+
+This complex field SHALL indicate the time when an RF tuning action has been performed, together with the integer number of the tuner that performed the tuning operation, the integer frequency of the MPEG-2 transport stream tuned to, and the integer program number of the MPEG-2 transport stream tuned to.
+
+The *tunerID* value SHALL be defined by Platform Specific Semantics.
+
+The *frequency* value SHALL be equal to the RF frequency acquired by the receiver.
+
+The *programNumber* value SHALL be equal to the MPEG-2 Program Number acquired by the receiver.
+
+### **B.10 SDV**
+
+This complex field SHALL indicate the time when a new Switched Digital Service has been selected, and the integer Source ID of that new service.
+
+The *sourceID* value SHALL be defined by Platform Specific Semantics.
+
+### **B.11 servicePresentation**
+
+This complex field SHALL indicate the time when presentation of a new service has started, together with the integer Source ID of the service being presented, the enumerated integer aspect ratio of the display area of the presentation, the integer resolution of the display area of the presentation, and the enumerated integer indication of whether audio is on or off for the service being presented.
+
+The *sourceID* value SHALL be defined by Platform Specific Semantics.
+
+The *aspectRatio* value SHALL be one of: 1 for 4:3, 2 for 16:9.
+
+The *resolution* value SHALL be defined by Platform Specific Semantics.
+
+The *audio* value SHALL be one of: 0 for audio off, 1 for audio on.
+
+### **B.12 segmentPresentation**
+
+This complex field SHALL indicate the time when a new segmentation descriptor is detected within a presentation by the platform, together with the integer Segment ID of that new segment as taken from that descriptor. Presentations MAY be from broadcast, from a DVR recording, from SDV, or from an On-Demand session.
+
+The *segmentID* value SHALL be defined by Platform Specific Semantics.
+
+### **B.13 DPI**
+
+This complex field SHALL indicate the time when an existing service has been replaced by new Digital Program Insertion service, together with the integer Source ID of the service being replaced, the integer Source ID of the new destination service, the enumerated integer source of the replacement, and the integer switch level of the replacement.
+
+The *sourceID* and *replacementID* values SHALL be defined by Platform Specific Semantics.
+
+The *replacementSource* value SHALL be one of: 1 for In-transport, 2 for Out-of-transport, 3 for From-Memory.
+
+The *switchLevel* value SHALL be one of: 0 for L0 switch, 1 for L1 switch.
+
+### **B.14 inputEvent**
+
+This complex field SHALL indicate the time when a key click from a remote control or other input device has been detected by the platform, together with the integer *KeyCode* value itself.
+
+The *keyCode* value SHALL be defined by Platform Specific Semantics.
+
+### **B.15 applicationLoadRequested**
+
+This complex field SHALL indicate the time when the platform has received a request to load an application, together with an integer value that identifies the application and an enumerated integer application type.
+
+The *appID* value SHALL be defined by Platform Specific Semantics.
+
+The *appType* value SHALL be one of: 1 for OCAP, 2 for ETV, or 3 for other, as selected by Platform Specific Semantics.
+
+### **B.16 applicationLoaded**
+
+This complex field SHALL indicate the time when the platform has successfully loaded an application, together with an integer value that identifies the application, an enumerated integer application type, an integer value that specifies the number of resource files that have currently been loaded for the application, the enumerated integer transport load mechanism, and the enumerated initial state of the application.
+
+The *appID* value SHALL be defined by Platform Specific Semantics.
+
+The *appType* value SHALL be one of: 1 for OCAP, 2 for ETV, or 3 for other, as selected by Platform Specific Semantics.
+
+The *numResourceFiles* value SHALL be defined by Platform Specific Semantics.
+
+The *transportProtocol* value SHALL be one of: 1 for In-Band-Object-Carousel, 2 for Out-Of-Band-Object-Carousel, 3 for HTTP, as selected by Platform Specific Semantics.
+
+The *controlCode* value SHALL be one of: 1 for LOADED, 2 for PAUSED, 3 for RUNNING, as selected by Platform Specific Semantics.
+
+### **B.17 applicationLifecycle**
+
+This complex field SHALL indicate the time when the platform has modified the state of an application, together with an integer value that identifies the application and an enumerated integer application type.
+
+The *appID* value SHALL be defined by Platform Specific Semantics.
+
+The *appType* value SHALL be one of: 1 for OCAP, 2 for ETV, or 3 for other, as selected by Platform Specific Semantics.
+
+The *lifeCycleState* value SHALL be one of: 1 for LAUNCHED, 2 for PAUSED, 3 for RESUMED, 4 for TERMINATED, as selected by Platform Specific Semantics.
+
+### **B.18 environmentSelection**
+
+This complex field SHALL indicate the time when the platform has successfully switched to a new operating environment, together with the enumerated integer environment identifier.
+
+The *environment* value SHALL be one of: 1 for Cable, 2 for Non-Cable, as selected by Platform Specific Semantics.
+
+### **B.19 applicationMode**
+
+This complex field SHALL indicate the time when the platform has modified the mode of an application, together with an integer value that identifies the application and an enumerated integer application type.
+
+The *appID* value SHALL be defined by Platform Specific Semantics.
+
+The *appType* value SHALL be one of: 1 for OCAP, 2 for ETV, or 3 for other, as selected by Platform Specific Semantics.
+
+The *mode* value SHALL be one of: 1 for CROSS-ENVIRONMENT, 2 for BACKGROUND, 3 for NORMAL, as selected by Platform Specific Semantics.
+
+### **B.20 application**
+
+This complex field SHALL indicate the time when an application has conveyed a private data set to the platform, together with the binary data itself. The hexBinary *privateData* value SHALL be forwarded to the metrics collection without further interpretation.
+
+
+
+
+
+## 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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@@ -0,0 +1,980 @@
+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.206**
+
+(03/2013)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Application for Interactive Digital Television
+
+---
+
+**Architecture for an application control  
+framework using integrated broadcast and  
+broadband digital television**
+
+Recommendation ITU-T J.206
+
+
+
+# Recommendation ITU-T J.206
+
+# Architecture for an application control framework using integrated broadcast and broadband digital television
+
+## Summary
+
+Consumer electronics devices are more and more connected every day. This tendency has also reached digital television (DTV) receivers, Blu-ray players, personal video recorder (PVR) devices and even games consoles.
+
+Taking advantage of the increasing broadband availability, consumer electronics manufacturers are embedding in their products applications that are able to retrieve content from proprietary services available through the Internet. Additionally, computational capabilities and increasing persistent storage availability in these devices will allow end users to customize their devices by installing new applications; this is already occurring with mobile phones, tablets and games consoles.
+
+In the same way, DTV broadcasters are extending their systems in order to use broadband availability to improve their services by adding interactive non-linear and on-demand content to the services they traditionally offer.
+
+However, most of the current solutions are closed/proprietary solutions and focused on each industry's specific problems.
+
+In alignment with Recommendation ITU-T J.205, *Requirements for an application control framework using integrated broadcast and broadband digital television*, this contribution proposes a study on the architecture and implementation for an application control framework for DTV enabled devices. This framework would be responsible for managing and controlling the interactive content and applications available through DTV services, installed by the end user or embedded by the device manufacturer, and providing a unified execution environment for them.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group |
+|---------|----------------|------------|-------------|
+| 1.0     | ITU-T J.206    | 2013-03-01 | 9           |
+
+## 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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 .....                                                                                                                                                                  | 1    |
+| 3.1  | Terms defined elsewhere .....                                                                                                                                                      | 1    |
+| 3.2  | Terms defined in this Recommendation.....                                                                                                                                          | 3    |
+| 4    | Abbreviations and acronyms .....                                                                                                                                                   | 4    |
+| 5    | Conventions .....                                                                                                                                                                  | 4    |
+| 6    | Overall architecture .....                                                                                                                                                         | 4    |
+| 6.1  | The IBB application structure .....                                                                                                                                                | 5    |
+| 6.2  | Accessibility considerations .....                                                                                                                                                 | 6    |
+| 7    | IBB DTV receiver architecture.....                                                                                                                                                 | 6    |
+| 7.1  | High level architecture based on the ITU-T J.200-series of<br>Recommendations .....                                                                                                | 6    |
+| 8    | IBB DTV receiver behaviour.....                                                                                                                                                    | 9    |
+| 8.1  | Coexistence and backward compatibility with existing DTV receivers,<br>which adhere to Recommendations [ITU-T J.200], [b-ITU-T J.201],<br>[b-ITU-T H.761] and [b-ITU-T J.202]..... | 10   |
+| 8.2  | System expandability: plug-in support (optional) .....                                                                                                                             | 10   |
+| 8.3  | Support for delivering IBB applications using any combination of<br>delivery mechanisms .....                                                                                      | 10   |
+| 8.4  | Application life cycle model .....                                                                                                                                                 | 14   |
+| 8.5  | IBB application control .....                                                                                                                                                      | 15   |
+| 8.6  | The application catalogue user interface (AppCatUI).....                                                                                                                           | 16   |
+| 8.7  | IBB installable application management.....                                                                                                                                        | 18   |
+| 8.8  | Internet application repository.....                                                                                                                                               | 20   |
+| 8.9  | Ensuring DTV service integrity and IBB application permissions policy ....                                                                                                         | 21   |
+| 8.10 | Ensure user privacy and user data protection .....                                                                                                                                 | 23   |
+| 8.11 | User account management.....                                                                                                                                                       | 23   |
+| 8.12 | Location awareness (optional).....                                                                                                                                                 | 25   |
+| 8.13 | DTV service synchronization (stream events) .....                                                                                                                                  | 25   |
+| 8.14 | Media content streaming (optional).....                                                                                                                                            | 25   |
+| 8.15 | Cryptographic API.....                                                                                                                                                             | 25   |
+| 8.16 | Persistent storage .....                                                                                                                                                           | 26   |
+|      | Bibliography.....                                                                                                                                                                  | 27   |
+
+
+
+# Recommendation ITU-T J.206
+
+## Architecture for an application control framework using integrated broadcast and broadband digital television
+
+# 1 Scope
+
+This Recommendation defines a high-level architecture for an application control framework based on integrated broadcast and broadband (IBB) digital television (DTV) services intended to harmonize the behaviour and the interaction of a variety of types of applications, provided by network agnostic delivery mechanisms which include broadcast delivered, broadband delivered, pre-installed, delivered via application repository and home area network delivered.
+
+# 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 J.200] Recommendation ITU-T J.200 (2010), *Worldwide common core – Application environment for digital interactive television services*.
+
+[ITU-T J.205] Recommendation ITU-T J.205 (2012), *Requirements for an application control framework using integrated broadcast and broadband digital television*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 application** [ITU-T J.205]: Any active DTV service content aimed at end-user interaction.
+
+**3.1.2 application catalogue** [ITU-T J.205]: Data structure listing available applications (interactive content). This data structure is local to the IBB DTV receiver, and describes the IBB applications installed on the IBB DTV receiver.
+
+**3.1.3 application catalogue user interface** [ITU-T J.205]: A user interface functionality over the IBB DTV receiver, intended to allow the end user to browse the available applications in the application catalogue or to query application catalogues exposed by application repositories. Also, it lists applications that are currently available in the selected IBB DTV service or broadcast DTV service.
+
+**3.1.4 application component** [ITU-T J.205]: A block of data that forms part of an application. Application component types are: code, resources, metadata, control and user settings.
+
+**3.1.5 application control data structure** [ITU-T J.205]: Data structures transmitted within the integrated broadcast and broadband (IBB) DTV service to control IBB applications (e.g., AIT in [b-GINGA-J], [b-MHP]).
+
+**3.1.6 application installation package** [ITU-T J.205]: Application delivery mechanism in which several application components are bundled together in a single file.
+
+**3.1.7 application repository** [ITU-T J.205]: Entity, reachable through the broadband channel, that provides access to integrated broadcast and broadband (IBB) applications contained in it. These IBB applications can be downloaded and installed on the IBB DTV receiver, manually, by the end user, or, in case of being signalled within an IBB DTV service, launched or installed automatically under the IBB DTV service's control using the IBB application control mechanism. An application repository can be managed by IBB service providers, IBB DTV receiver manufacturers, or other third party entities.
+
+**3.1.8 bridge elements** [ITU-T J.200]: A mechanism for applications that allows bidirectional mapping between execution engine and presentation engine.
+
+**3.1.9 broadband channel** [ITU-T J.205]: A medium used to deliver interactive content. Usually this medium is based on the Internet and allows the delivery of non-linear and on-demand content. A broadband channel allows access to servers that may be located in the Internet.
+
+**3.1.10 broadcast channel** [ITU-T J.205]: A medium used to deliver digital television (DTV) services. Examples: free to air, satellite and cable.
+
+**3.1.11 broadcast DTV service** [ITU-T J.205]: Any digital television (DTV) service, delivered through a broadcast channel.
+
+**3.1.12 cable IBB DTV service** [ITU-T J.205]: An integrated broadcast and broadband digital television (DTV) service managed by cable operators.
+
+**3.1.13 DTV service** [ITU-T J.205]: This is the unit for delivering audio-visual content to the end users. In a more extensive definition (the one adopted in this Recommendation), this unit also comprehends the delivery of interactive content. It constitutes an editorially consistent whole and it is an aggregation of different kinds of service components.
+
+**3.1.14 DTV service component delivery mechanism** [ITU-T J.205]: Used to refer to any mechanism, channel or medium to deliver digital television (DTV) service components to an integrated broadcast and broadband (IBB) DTV receiver.
+
+**3.1.15 DTV service content** [ITU-T J.205]: Audio/visual/interactive components delivered within a digital television (DTV) service as single editorially consistent whole.
+
+**3.1.16 execution engine** [ITU-T J.200]: A subsystem in a receiver that evaluates and executes procedural applications consisting of computer language instructions and associated data and media content. An execution engine may be implemented with an operating system, computer language compilers, interpreters and application programming interfaces (APIs), which a procedural application may use to present audiovisual content, interact with a user, or execute other tasks that are not evident to the user. A common example of an execution engine is the JavaTV software environment, using the Java programming language and byte code interpreter, JavaTV APIs, and a Java virtual machine for program execution.
+
+**3.1.17 IBB application** [ITU-T J.205]: An application that is meant to be handled and executed within an integrated broadcast and broadband (IBB) application control framework defined by this Recommendation. Such applications can have their application contents delivered using different application component delivery mechanisms.
+
+**3.1.18 IBB application control mechanism** [ITU-T J.205]: A mechanism used by integrated broadcast and broadband (IBB) digital television (DTV) service providers to signal and control IBB applications associated to their respective IBB DTV services. The mechanism contemplates the transmission of an IBB DTV service's application control data structure within the IBB DTV service. Such data structure can support the signalling of IBB applications that are retrievable from the broadcast channel or through the broadband channel from HTTP servers or application repositories.
+
+- 3.1.19 IBB DTV receiver** [ITU-T J.205]: A device capable of receiving and displaying DTV services as well as integrated broadcast and broadband (IBB) DTV services.
+- 3.1.20 IBB DTV service** [ITU-T J.205]: A service that simultaneously provides an integrated experience of broadcasting and interactivity relating to media content, data and applications from multiple sources, where the interactivity is sometimes associated with broadcasting programmes.
+- 3.1.21 IBB DTV service provider** [ITU-T J.205]: An entity (i.e., broadcasters) making available and delivering IBB DTV services.
+- 3.1.22 IBB installable application** [ITU-T J.205]: An integrated broadcast and broadband (IBB) application that can be downloaded and saved onto the IBB DTV receiver's persistent storage for later usage.
+- 3.1.23 IBB resident application** [ITU-T J.205]: An integrated broadcast and broadband (IBB) application embedded into the IBB DTV receiver by the device manufacturer.
+- 3.1.24 presentation engine** [ITU-T J.200]: A subsystem in a receiver that evaluates and presents declarative applications consisting of content, such as audio, video, graphics, and text, primarily based on presentation rules defined in the presentation engine. A presentation engine also responds to formatting information, or "markup", associated with the content, to user inputs, and to script statements, which control presentation behaviour and initiate other processes in response to user input and other events. A common example of a presentation engine is an HTML browser, capable of displaying text and graphic content formatted in HTML [b-W3C HTML], with interactive behaviour programmed in ECMAScript [b-ECMAScript].
+- 3.1.25 remote application catalogue** [ITU-T J.205]: application catalogue exported from an application repository. This differs from the normal application catalogue in that, if the remote application catalogue is very large, there must be a mechanism for querying it and retrieving it in small parts that can be handled in an efficient way by the integrated broadcast and broadband (IBB) DTV receiver.
+- 3.1.26 service associated IBB application** [ITU-T J.205]: An application that is part of the integrated broadcast and broadband (IBB) DTV service tuned by the user at a given time.
+- 3.1.27 service exclusive IBB application** [ITU-T J.205]: An application that is listed as a component of an integrated broadcast and broadband (IBB) DTV service and its life cycle is strictly tied to the exhibition of such an IBB DTV service.
+- 3.1.28 service shared IBB application** [ITU-T J.205]: An application that is listed as a component of several different integrated broadcast and broadband (IBB) DTV services. Its life cycle is for as long as any of those IBB DTV services are being exhibited.
+- 3.1.29 stand-alone IBB application** [ITU-T J.205]: Resident or downloaded integrated broadcast and broadband (IBB) installable application that is not part of an IBB DTV service. Such an application can be created by an authorized IBB application provider, and typically delivered through the application repository.
+
+## **3.2 Terms defined in this Recommendation**
+
+This Recommendation defines the following terms:
+
+- 3.2.1 application descriptor file**: A file containing metadata information for an application.
+- 3.2.2 IBB application provider**: An organization that makes available an IBB application; in the most common case, it is the application developer.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|          |                                                             |
+|----------|-------------------------------------------------------------|
+| ACF      | Application Control Framework                               |
+| AIP      | Application Install Package                                 |
+| AIT      | Application Information Table                               |
+| API      | Application Programming Interface                           |
+| AppCatUI | Application Catalogue User Interface                        |
+| DAV      | Distributed Authoring and Versioning                        |
+| DRM      | Digital Right Management                                    |
+| DSMCC DC | Digital Storage Media Command and Control – Data Carousel   |
+| DSMCC OC | Digital Storage Media Command and Control – Object Carousel |
+| DTV      | Digital Television                                          |
+| EPG      | Electronic Programme Guide                                  |
+| HAN      | Home Area Network                                           |
+| HTTP     | Hyper Text Transfer Protocol                                |
+| HTTPS    | Secure Hyper Text Transfer Protocol                         |
+| IBB      | Integrated Broadcast and Broadband                          |
+| NFS      | Network File System                                         |
+| OSD      | On-Screen Display                                           |
+| PVR      | Personal Video Recorder                                     |
+| ROM      | Read-Only Memory                                            |
+| RTP      | Real Time Protocol                                          |
+| RTSP     | Real Time Streaming Protocol                                |
+| URL      | Universal Resource Locator                                  |
+
+# 5 Conventions
+
+None.
+
+# 6 Overall architecture
+
+Based on the system analysis described in clause 7 of [ITU-T J.205], a system covered by this Recommendation should implement the overall architecture shown in Figure 6-1.
+
+The DTV service provider broadcasts the DTV service in which IBB application components can be multiplexed for one or more IBB applications. At the same time, the DTV service provider can make available the same or different sets of IBB application components in a server or IBB application repository reachable through the Internet.
+
+In the same way, other entities can make available IBB application components, as well as IBB application repositories.
+
+The IBB DTV receiver has the capabilities to decode the DTV service and also support an implementation of the IBB application control framework (IBB ACF). The IBB ACF is the system's
+
+component in charge of collecting IBB application components from several possible sources and interpreting and/or executing them in the IBB DTV receiver.
+
+![Figure 6-1: Overview of the integrated broadcast and broadband system architecture. The diagram shows a DTV service provider (broadcaster) sending a DTV broadcast signal to an IBB DTV receiver. The IBB DTV receiver contains a DTV service decoder and an IBB application control framework. The IBB application control framework is connected to a broadband network, which in turn is connected to servers from manufacturers of IBB DTV receivers and third-party servers. The IBB application control framework is also connected to a home area network (HAN) containing a monitor, a tablet, and a smartphone. A legend at the bottom indicates that blue arrows represent DTV service components (video, audio, closed caption, etc.) and red arrows represent IBB application components (control, source, metadata, resources and settings).](5b4e774d63e0e0ed73801a9247755e5f_img.jpg)
+
+The diagram illustrates the system architecture. On the left, a 'DTV service provider (aka broadcaster)' box contains a 'DTV service' component and a 'Broadcaster's server'. An orange arrow labeled 'DTV broadcast signal' points from the 'DTV service' to the 'IBB DTV receiver' on the right. The 'IBB DTV receiver' box contains a 'DTV service decoder' and an 'IBB application control framework'. Below the broadcaster, 'Servers from manufacturers of IBB DTV receivers' and 'Third party servers' are shown. Red arrows point from these servers to a central 'Broadband network' (represented by a globe icon). From the 'Broadband network', red arrows point to the 'IBB application control framework' and to a 'Home area network' (represented by a house icon). The 'Home area network' contains a monitor, a tablet, and a smartphone. Blue arrows point from the 'DTV service decoder' to the 'IBB application control framework'. A legend at the bottom shows a blue line for 'DTV service components (video, audio, closed caption, etc.)' and a red line for 'IBB application components (control, source, metadata, resources and settings)'. The label 'J.206(13)\_F6-1' is in the bottom right corner.
+
+Figure 6-1: Overview of the integrated broadcast and broadband system architecture. The diagram shows a DTV service provider (broadcaster) sending a DTV broadcast signal to an IBB DTV receiver. The IBB DTV receiver contains a DTV service decoder and an IBB application control framework. The IBB application control framework is connected to a broadband network, which in turn is connected to servers from manufacturers of IBB DTV receivers and third-party servers. The IBB application control framework is also connected to a home area network (HAN) containing a monitor, a tablet, and a smartphone. A legend at the bottom indicates that blue arrows represent DTV service components (video, audio, closed caption, etc.) and red arrows represent IBB application components (control, source, metadata, resources and settings).
+
+**Figure 6-1 – Overview of the integrated broadcast and broadband system architecture**
+
+When the DTV service provider delivers the control type of the IBB application component, the IBB ACF will present the IBB application seamlessly integrated with the DTV service. In another case, if the user launches an IBB application that is not related to the DTV service (a stand-alone IBB application), the IBB ACF will handle the application in such a way that it is completely separate from the DTV service.
+
+Figure 6-1 also depicts how the IBB application components can be delivered to the IBB DTV receiver using different channels and shows that they can also be shared among devices in the same home area network (HAN). For more details, refer to clause 8.3.
+
+The architecture recommended in [ITU-T J.200] is used as a basis (FR-ACF-01 of [ITU-T J.205]) and extended by this Recommendation in order to fulfil additional requirements listed in this document.
+
+This Recommendation also defines extensions to the presentation and execution engines as proposed by [ITU-T J.200] and described in [b-ITU-T J.201], [b-ITU-T H.761] and [b-ITU-T J.202].
+
+## 6.1 The IBB application structure
+
+An IBB application usually consists of a set of IBB application components (see Figure 6-2) classified in any of the following types:
+
+- **Code:** compiled binary, byte code, script (etc.) executables.
+- **Resources:** data files, fonts, images or any other content consumed by the application during code execution.
+- **Metadata:** additional information associated with the application, containing information for the user and for application execution. Metadata can be classified as:
+
+- **Metadata (info)**: comprising application description (unique identification, version, name, icon, provider, language, settings, etc.), location for retrieving an application's components, how it should be presented (dimensions on the screen, position, states, etc.), minimal requirements (minimal middleware version, minimal receiver capabilities, etc.), etc.
+  - **Metadata (security)**: information used for application authentication, permissions declaration and authorization for access to the receiver's functionalities and/or DTV service integration (signature, certificates, policy files, etc.).
+- **Control**: signalling mechanism used by the IBB DTV service provider in order to control when and how the application must be active/inactive, installed/removed, available/unavailable, visible/hidden, etc., or even if control must be left completely to the end user.
+- **User settings**: configuration parameters that may define some application customization or store users' preferences for using this application. As an example, user settings can be used to customize the application user interface, the application behaviour and personal data of the user (name, age, gender, email, address, etc.).
+
+![Diagram of IBB application components showing a table with five columns: Code, Resources, Metadata, Control, and User settings.](007b053fe94a8348f75128a584503fd0_img.jpg)
+
+| IBB application |           |          |         |               |
+|-----------------|-----------|----------|---------|---------------|
+| Code            | Resources | Metadata | Control | User settings |
+
+Diagram of IBB application components showing a table with five columns: Code, Resources, Metadata, Control, and User settings.
+
+J.206(13)\_F6-2
+
+**Figure 6-2 – IBB application components**
+
+Unlike conventional DTV applications, IBB application components can be delivered by a combination of multiple delivery channels. Metadata or any other information of an IBB application should be aligned with its delivery scenario.
+
+## 6.2 Accessibility considerations
+
+The architecture defined in this Recommendation allows any applications to control, present and interact with users in any way the applications intend. Hence, any applications which are aware of accessibility can be built upon this architecture.
+
+# 7 IBB DTV receiver architecture
+
+This clause provides an overview of the IBB DTV receiver architecture consisting of diagrams and summary descriptions of each of its functional blocks and components.
+
+## 7.1 High level architecture based on the ITU-T J.200-series of Recommendations
+
+The ITU-T J.200-series of Recommendations already provides a major number of definitions for the functional requirements, architecture and application programming interface (API) that can also be used in the context of IBB applications and IBB DTV services.
+
+The architecture recommended in [ITU-T J.200] is used as a basis, and extended by this Recommendation in order to fulfil additional requirements listed in this document.
+
+This Recommendation also defines extensions to the presentation and execution engines proposed by [ITU-T J.200] and described in [b-ITU-T J.201], [b-ITU-T H.761] and [b-ITU-T J.202].
+
+Figure 7-1 illustrates the high-level architecture proposed for an IBB DTV receiver.
+
+![Proposed high-level architecture for an IBB DTV receiver diagram showing layers from User interaction down to Hardware.](af7916c89a458fdab6c3f443217388ae_img.jpg)
+
+The diagram illustrates the proposed high-level architecture for an IBB DTV receiver, organized into several layers:
+
+- User interaction:** The top layer, containing 'Plug-in', 'Plug-in', 'ITU-T J.200 application', 'ITU-T J.200 application', 'IBB application', and 'IBB application'.
+- ITU-T J.200:** A layer containing 'Execution engine ITU-T J.202', 'Bridge elements', and 'Presentation engine ITU-T J.201'. To the right is an 'Application catalogue user interface'.
+- IBB application control framework:** A layer containing 'Application life cycle control' and 'Presentation control'. Below this are 'DTV integration' (with 'Application transport', 'DTV presentation control', and 'Broadcast RT events'), 'Device integration', 'Cryptography', 'User account manager', 'Plug-in manager', 'Location awareness', 'Security and authentication', 'User settings manager', and 'Installed application manager'.
+- DTV subsystem:** Contains 'Front end', 'Transport decoder', 'Video decoder', 'Conditional access', 'Audio decoder', 'Subtitle decoder', and 'Service information'.
+- Support subsystem:** Contains 'Networking', 'Storage', 'Media support', 'PVR', 'Streaming', and 'DRM'.
+- User interface subsystem:** Located to the right of the DTV and Support subsystems.
+- Operating system / drivers:** A layer below the subsystems.
+- Hardware:** The bottom-most layer.
+
+Dashed line box: optional components  
+Solid line box: mandatory components
+
+Proposed high-level architecture for an IBB DTV receiver diagram showing layers from User interaction down to Hardware.
+
+J.206(13)\_F7-1
+
+**Figure 7-1 – Proposed high-level architecture for an IBB DTV receiver**
+
+- **Hardware:** physical components of the IBB DTV receiver, comprising processing and decoding units, memory, display, remote control, tuner, etc.
+- **Operating system/drivers:** basic software stack in charge of low-level tasks and low-level access to the hardware components.
+- **DTV subsystem:** stack of software components responsible for the reception and exhibition of the DTV service. Usually, these software components act as proxies for specific physical components in the hardware which do the actual work:
+  - **Front-end:** This is the component in charge of selecting and receiving a certain DTV service.
+  - **Transport decoder:** component that does the decoding of the transport signal and breaks it in separate DTV service components. For example, this can be an MPEG-2 system demultiplexer.
+  - **Conditional access:** security component that checks user credentials/permissions to access a certain DTV service. Also it descrambles scrambled signals (FR-ACF-16 of [ITU-T J.205]).
+  - **Video decoder:** component responsible for decoding the DTV service's video content.
+  - **Audio decoder:** component responsible for decoding the DTV service's audio content.
+
+- **Subtitle decoder:** component responsible for decoding the DTV service's subtitle or closed-caption contents.
+  - **Service information:** component in charge of decoding the information contained in the DTV service signal, such as the electronic programme guide and service structure description.
+- **User interface subsystem:** This subsystem handles low-level functions for the user's interaction. Among the components of this subsystem are the IBB DTV receiver's on-screen display (OSD), remote control handling, etc.
+- **Support subsystem:** This subsystem aggregates a series of general purpose components used by the IBB application control framework.
+  - **Networking:** handles access to IP networks, providing support for Internet access and home area networks.
+  - **Storage:** handles access to the persistent storage area in the device or any other external storage device (FR-ACF-24 of [ITU-T J.205]).
+  - **Media support:** provides decoding/encoding support for different kinds of media such as images, audio, video, text, etc. (FR-ACF-23 of [ITU-T J.205]).
+  - **PVR:** provides access to the personal video recording functionality that may be present in the IBB DTV receiver (FR-ACF-25 of [ITU-T J.205]).
+  - **Streaming:** provides capabilities for decoding streamed content from external sources or encoding and streaming out content (FR-ACF-26 of [ITU-T J.205]).
+  - **Digital right management (DRM):** support for decoding/re-encoding media (FR-ACF-16 of [ITU-T J.205]).
+- **Native applications:** This is a placeholder for any application that may be present in the IBB DTV receiver and that is not related to the IBB ACF.
+- **IBB application control framework:** The IBB ACF subsystem is composed of the following components:
+  - **DTV integration:** This component handles the integration of the IBB ACF with the DTV subsystem. It is sub-divided into the following components:
+    - **Application transport:** is responsible for decoding the IBB application components transmitted in the DTV service. An example of this component is a DSMCC Object Carousel decoder (FR-ACF-03 of [ITU-T J.205]).
+    - **DTV presentation control:** allows both the IBB ACF and the IBB applications running on top of it, to control the presentation of the DTV service components such as audio, video or subtitles.
+    - **Broadcast real time (RT) events:** support for decoding application-level signalling sent by the IBB DTV service provider in the DTV service signal. For example: DSMCC stream events (FR-ACF-22 of [ITU-T J.205]).
+  - **Installed application manager:** in charge of managing all the IBB application components installed in the IBB DTV receiver, updating such application components whenever applicable and handling the installation of new ones. This component answers requests from the application catalogue interface or the application life cycle control (FR-ACF-05, FR-ACF-07 and FR-ACF-08 of [ITU-T J.205]).
+  - **Plug-in manager:** This component manages the plug-ins installed in the IBB DTV receiver, making them available to the requesting IBB applications. Plug-in updating, installing and uninstalling are also functions in the scope of this component (FR-ACF-28 and FR-ACF-29 of [ITU-T J.205]).
+
+- **User accounts manager:** This component manages the access to the different user accounts that can be registered within the IBB DTV receiver, and securely handles all the user information and credentials associated with such accounts. This component enables the secure sharing of access to user information, data and services that can be present in other devices or servers. Refer to clause 8.11 for further details (FR-ACF-17 of [ITU-T J.205]).
+- **User settings manager:** manages the settings information stored by the IBB applications in order to allow user customization (FR-ACF-18 of [ITU-T J.205]).
+- **Cryptography:** component that provides cryptography services such as digital signature and encryption to any other component in the IBB ACF or the IBB applications (FR-ACF-27 of [ITU-T J.205]).
+- **Security and authentication:** responsible for verifying the authenticity and origin of the IBB application, identifying whether the application is provided by a trusted source and whether the application is granted permission by the IBB DTV service provider to be integrated with its DTV service. Having resolved the IBB application permissions, it is responsible for sandboxing the application, allowing access only to the functions that have been granted to it (FR-ACF-13, FR-ACF-14 and FR-ACF-15 of [ITU-T J.205]).
+- **Device integration:** This component is responsible for handling the discovering and interaction with other devices in the home area network (FR-ACF-20 of [ITU-T J.205]).
+- **Location awareness:** This is in charge of making available to the IBB application information related to the location of the IBB DTV receiver (FR-ACF-19 of [ITU-T J.205]).
+- **Application life cycle control:** This is the most important component in the IBB ACF. Its responsibility is to manage the life cycle and states of each one of the IBB applications that the IBB ACF is aware of at a given time (FR-ACF-09, FR-ACF-11 and FR-ACF-12 of [ITU-T J.205]).
+- **Presentation control:** This component manages the presentation and focus control between the different IBB applications that can be in execution, the application catalogue user interface and coordinates presentation with native applications. It acts as a synchronization agent between the IBB ACF, the user interface subsystem and other native applications that may require access to the screen and user input.
+- **Application catalogue user interface:** This is the user interface component provided by the IBB ACF intended for listing the available applications that can be launched by the user. It also allows the user to browse IBB application repositories, and install, update or uninstall IBB applications (FR-ACF-04 and FR-ACF-10 of [ITU-T J.205]).
+- **ITU-T J.200 components:** IBB applications execute on top of the execution engine or presentation engine, as defined by [ITU-T J.200] and described in [b-ITU-T J.201], [b-ITU-T H.761] and [b-ITU-T J.202] (FR-ACF-01 of [ITU-T J.205]).
+
+# 8 IBB DTV receiver behaviour
+
+This clause describes how the requirements defined in [ITU-T J.205] are achieved by the architecture described in clause 7.
+
+The following clauses detail the behaviour of the main architectural functional blocks, which should be implemented by an IBB DTV receiver that supports the proposed architecture for the IBB ACF.
+
+## 8.1 Coexistence and backward compatibility with existing DTV receivers, which adhere to Recommendations [ITU-T J.200], [b-ITU-T J.201], [b-ITU-T H.761] and [b-ITU-T J.202]
+
+The IBB DTV receivers should support seamless interoperability with conventional broadcast applications as supported in [ITU-T J.200], [b-ITU-T J.201], [b-ITU-T H.761] and [b-ITU-T J.202] and IBB applications (FR-ACF-02 of [ITU-T J.205]). Gradual evolution of existing DTV services to IBB DTV services must be possible in such a way that:
+
+1. IBB application components should be ignored or not detected by already deployed receivers intended for conventional DTV services and with no support for IBB applications. This also applies to IBB receivers that are not connected to a broadband connection.
+2. IBB receivers should be capable of exhibiting content and applications from conventional DTV services.
+
+![Diagram illustrating the interoperability of an IBB DTV receiver with conventional DTV applications. The diagram is split into two horizontal sections by a dashed line. The top section shows a 'DTV service provider' box containing a 'Conventional DTV service' (yellow) with an orange arrow pointing to an 'IBB DTV receiver' box containing an 'ITU-T J.200 application' (yellow). The bottom section shows a 'DTV service provider' box containing an 'IBB DTV service' (green) with a green arrow pointing to an 'IBB DTV receiver' box containing an 'IBB application' (green). A label 'J.206(13)_F8-1' is in the bottom right corner.](1a827b10290f33d4fec04d0e8ef7a897_img.jpg)
+
+J.206(13)\_F8-1
+
+Diagram illustrating the interoperability of an IBB DTV receiver with conventional DTV applications. The diagram is split into two horizontal sections by a dashed line. The top section shows a 'DTV service provider' box containing a 'Conventional DTV service' (yellow) with an orange arrow pointing to an 'IBB DTV receiver' box containing an 'ITU-T J.200 application' (yellow). The bottom section shows a 'DTV service provider' box containing an 'IBB DTV service' (green) with a green arrow pointing to an 'IBB DTV receiver' box containing an 'IBB application' (green). A label 'J.206(13)\_F8-1' is in the bottom right corner.
+
+**Figure 8-1 – IBB DTV receiver should support interoperability with conventional DTV applications (based on [ITU-T J.200])**
+
+The end-user experience when navigating through DTV services and IBB DTV services must be as transparent as possible (FR-ACF-02 of [ITU-T J.205]). See Figure 8-1.
+
+## 8.2 System expandability: plug-in support (optional)
+
+The ACF capabilities can be extended by the installation of plug-in modules into the IBB DTV receiver (FR-ACF-28 and FR-ACF-29 of [ITU-T J.205]).
+
+Plug-in modules should register themselves and the interfaces for the services they provide into the IBB DTV receiver's extensions registry.
+
+IBB applications can query the extensions registry looking for some specific functionality or interface, and then make use of such extended functionality.
+
+## 8.3 Support for delivering IBB applications using any combination of delivery mechanisms
+
+IBB application components from the same application can be delivered through different channels (FR-ACF-03 of [ITU-T J.205]).
+
+Delivery of an IBB application can be classified in the following cases:
+
+- a. All the IBB application's components are delivered by the broadcast channel.
+
+In this case, they can be transmitted using the mechanisms already provided by middleware specifications in conformance with [ITU-T J.200] such as [b-MHP], [b-ARIB B.24], [b-ARIB B.23], [b-GINGA-J] or [b-GINGA-NCL], for example:
+
+- Code and resources: delivered using DSMCC Carousel.
+- Metadata: delivered using DSMCC Carousel (e.g., signature and permission information), AIT table (e.g., application name, application arguments, application type, middleware version required, etc.) and/or DSMCC stream events.
+- Control: IBB application delivered using AIT table control\_code field or any other equivalent mechanism.
+
+b. All the IBB application's components are delivered by the broadband channel. In this case, these components can be retrieved as an AIP containing the code, resources and metadata. Alternatively files for code, resources and metadata can be retrieved individually from an HTTP server. Control may still be obtained from the broadcast signal or a network server through the broadband channel.
+
+c. Integrated delivery of an IBB application. This occurs when some parts of its components are retrieved from the broadcast channel and other parts from the broadband channel in any combination of the two previous cases.
+
+d. IBB installable applications. IBB DTV receivers may have a persistent storage space for installing IBB installable applications. Once installed, these applications are available to the user at any time. IBB installable applications can be downloaded into the receiver in the following ways:
+
+d.1. Automatically, when signalled in a selected service (broadcast or broadband), a special signalling mechanism can be used in order to indicate that the application is to be installed in the receiver. Such a mechanism is provided by the AIT's UNBOUND control code in [b-GINGA-J] or [b-GINGA-NCL]. In this case, application components delivery can happen in any of the modalities described in a, b or c. In the case of IBB installable applications, they are not required to be available to receivers or continuously transmitted in the broadcast signal during the time they are signalled as available by the IBB DTV service provider.
+
+d.2. Manually by the user (user installed application), through an AppCatUI provided by the receiver. In this case, the IBB installable application's sources can be diversified (i.e., an application repository, another device in the HAN, pluggable storage device, etc.).
+
+e. IBB resident applications. These are applications embedded in the IBB DTV receiver by its manufacturer (FR-ACF-08 of [ITU-T J.205]). Usually they are stored in the receiver's ROM, or bundled within the receiver's firmware. These applications may not be uninstalled by the end user. Installation, updating and removal of these applications should be exclusively the right of the IBB DTV receiver's manufacturer.
+
+In the case of the user settings, a default set of values can be transmitted with the application using any of the methods described above. For actual values (customized by the user), the following alternatives are possible:
+
+- stored in the receiver's persistent storage (most usual case); or
+- shared among several devices present in the HAN.
+
+Table 1 summarizes the above-described cases:
+
+**Table 1 – Application components and applicable delivery transports**
+
+| Application component | Delivery channel                                                                   |                                                                                                                                                 |                                                                                                 |                                                                                                                                                 |                                                                                                 |
+|-----------------------|------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------|
+|                       | Broadcast channel                                                                  | Broadband channel                                                                                                                               | Previously installed in the receiver's persistent storage                                       | Via application repository                                                                                                                      | Home area network (HAN)                                                                         |
+| Code                  | DSMCC DC/OC                                                                        | Delivered within AIP <sup>a)</sup>                                                                                                              | Storage mechanism is implementation dependent                                                   | Delivered within the AIP <sup>a)</sup>                                                                                                          | Delivered within the AIP <sup>b)</sup>                                                          |
+| Resources             | DSMCC DC/OC                                                                        | 1. Delivered within the AIP <sup>a)</sup><br>2. HTTP/HTTPS protocols in the case of single file<br>3. RTP/RTSP protocols in the case of streams | Storage mechanism is implementation dependent                                                   | 1. Delivered within the AIP <sup>a)</sup><br>2. HTTP/HTTPS protocols in the case of single file<br>3. RTP/RTSP protocols in the case of streams | 1. Delivered within the AIP <sup>b)</sup><br>2. Using the file sharing protocol defined for HAN |
+| Metadata (info)       | 1. AIT table<br>2. Application descriptor file in DSMCC Carousel                   | 1. Application descriptor file retrieved using HTTP protocol<br>2. Contained in the AIP <sup>a)</sup>                                           | Application descriptor file contained in the AIP must be stored together with other AIP content | Application descriptor file contained in the AIP                                                                                                | Application descriptor file contained in the AIP <sup>b)</sup>                                  |
+| Metadata (security)   | Application descriptor file and other files in DSMCC Carousel                      |                                                                                                                                                 |                                                                                                 |                                                                                                                                                 |                                                                                                 |
+| Control               | AIT as in [b-MHP], [b-GINGA-J] or [b-GINGA-NCL]; or any other equivalent mechanism | Service associated IBB applications                                                                                                             | Stand-alone IBB applications<br>Launched by the user from the AppCatUI                          |                                                                                                                                                 |                                                                                                 |
+| User settings         | –                                                                                  | See remote user settings                                                                                                                        | See user settings and user persistent storage                                                   | See remote user settings                                                                                                                        | User settings<br>Sharing protocol<br>Defined for HAN                                            |
+
+<sup>a)</sup> AIP is retrieved using the HTTP protocol.
+
+<sup>b)</sup> AIP is retrieved using an application sharing protocol defined for HAN.
+
+When using an AIP, code, resources and metadata would usually be bundled together in the same package.
+
+Table 2 provides a high-level mapping of which ACF functional blocks are responsible for handling each type of IBB application component.
+
+**Table 2 – Functional block map for handling of IBB application components**
+
+| IBB application component | ACF functional block                                                                           |
+|---------------------------|------------------------------------------------------------------------------------------------|
+| Code                      | Execution engine [b-ITU-T J.202]/Presentation engine [b-ITU-T J.201]                           |
+| Resources                 | IBB application in general. They can be used for many purposes, depending on the resource type |
+| Metadata (info)           | Application catalogue user interface, presentation control, application transport              |
+| Metadata (security)       | Security and authentication                                                                    |
+| Control                   | Application life cycle control, application catalogue user interface                           |
+| User settings             | User settings manager, user account manager                                                    |
+
+Figure 8-2 summarizes the several mechanisms available to deliver and store the IBB application's components.
+
+![Figure 8-2: IBB application component delivery and storage mechanisms. The diagram is divided into three main vertical sections: Broadcast channel, Broadband channel, and Receiver/HAN. Each section contains boxes representing different delivery mechanisms and the components they handle. A mouse cursor is visible over the AIT box in the Broadcast channel section.](8fa679f79a1bb1f527cba9f29e784e89_img.jpg)
+
+The diagram illustrates the delivery and storage mechanisms for IBB application components across three main categories:
+
+- Broadcast channel:**
+  - DSMCC OC:** Contains Code, Resources, Metadata (info), and Metadata (security).
+  - DSMCC stream events:** Contains Control.
+  - AIT:** Contains Metadata (info) and Control. A mouse cursor is pointing at this box.
+- Broadband channel:**
+  - HTTP:** Contains Code, Resources, Metadata (info), and Metadata (security).
+  - Application repository - Using AIP:** Contains Code, Resources, Metadata (info), and Metadata (security).
+  - RTP/RTSP:** Contains Resources.
+- Receiver:**
+  - Application catalogue user interface:** Contains Control.
+  - Persistent storage:** Contains Code, Resources, Metadata (info), Metadata (security), and User settings.
+  - USB/AIP:** Contains Code, Resources, Metadata (info), and Metadata (security).
+- HAN:**
+  - Application sharing protocol/AIP:** Contains Code, Resources, Metadata (info), and Metadata (security).
+  - User settings sharing protocol:** Contains User settings.
+
+Figure 8-2: IBB application component delivery and storage mechanisms. The diagram is divided into three main vertical sections: Broadcast channel, Broadband channel, and Receiver/HAN. Each section contains boxes representing different delivery mechanisms and the components they handle. A mouse cursor is visible over the AIT box in the Broadcast channel section.
+
+**Figure 8-2 – IBB application component delivery and storage mechanisms**
+
+#### 8.3.1 Application descriptor file
+
+In the case of IBB applications delivered through the broadcast channel some metadata (info) is contained in the broadcast data structures (e.g., the AIT or other equivalent signalling mechanism).
+
+On the other hand, when delivering the application through other delivery mechanisms, such metadata must be delivered in an application descriptor file. Optionally, it should be possible to use the application description file for delivering metadata through the broadcast channel, by including such a file within the DSMCC Carousel.
+
+Optionally, the metadata (security) may also be included in the application description file, allowing the delivery of all metadata in a single data structure.
+
+#### 8.3.2 Rules for choosing the service associated IBB application's source
+
+The same IBB application can be made available through different channels (or delivery mechanisms) at the same time. From the end-user viewpoint, the IBB application delivery mechanism should be as transparent as possible.
+
+Table 3 should be supported by the IBB DTV receiver:
+
+**Table 3 – Application source decision table**
+
+| <b>ACTION</b>                                                                                    | <b>Already<br/>INSTALLED<br/>or RESIDENT</b> | <b>Version of the<br/>installed IBB<br/>application is the<br/>same or newer</b> | <b>Is it an<br/>installable IBB<br/>application?</b> | <b>Is the IBB<br/>application<br/>transmitted in the<br/>current selected<br/>service?</b>                                                  |
+|--------------------------------------------------------------------------------------------------|----------------------------------------------|----------------------------------------------------------------------------------|------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------|
+| Download from the available source, avoiding interruption of the service exhibition              | No                                           | –                                                                                | No                                                   | No                                                                                                                                          |
+| Download from the current selected service                                                       | No                                           | –                                                                                | No                                                   | Yes                                                                                                                                         |
+| Download from the available source, avoiding interruption of the service exhibition, and install | No                                           | –                                                                                | Yes                                                  | No                                                                                                                                          |
+| Download from the current selected service and install                                           | No                                           | –                                                                                | Yes                                                  | Yes                                                                                                                                         |
+|                                                                                                  | Yes                                          | No and application is not resident                                               | Yes                                                  | Yes                                                                                                                                         |
+| Use the installed application                                                                    | Yes                                          | Yes                                                                              | Yes                                                  | –                                                                                                                                           |
+|                                                                                                  | Yes                                          | No or application is resident                                                    | Yes                                                  | No and service exhibition needs to be interrupted to download the latest version, or application is not currently available for downloading |
+| Download and install                                                                             | Yes                                          | No and application is not resident                                               | Yes                                                  | No. Service exhibition can continue for downloading the latest version                                                                      |
+
+## 8.4 Application life cycle model
+
+The IBB application life cycle model should support the models used by middleware implementations adherent to [ITU-T J.200]. For example, the Xlet life cycle model defined by [b-CDC] and adopted in [b-MHP], [b-ARIB B.23] and [b-GINGA-J] or also the application life cycle model used in [b-ARIB B.24] and [b-GINGA-NCL].
+
+As commonly defined by most of the middleware specifications conformant with [ITU-T J.200] ([b-MHP], [b-ETSI TS 102 728], [b-GINGA-J], [b-GINGA-NCL], [b-ACAP], [b-OCAP], [b-ARIB B.23]), applications can be signalled as being bounded to the service or not. Defined rules are:
+
+- Execution of service-exclusive (service bounded) applications must be terminated when the service exhibition is stopped.
+- In the case of service-shared (service unbounded) applications, execution should continue in the case of the same application being also signalled in the service that is selected next.
+
+Both service exclusive and service shared IBB applications are to be considered service associated IBB applications and must be terminated in the case of no longer being signalled within the currently selected IBB DTV service.
+
+## 8.5 IBB application control
+
+The IBB DTV service provider can control the execution, availability and visibility only of the service associated IBB applications, using the control component of the application (e.g., AIT) (FR-ACF-11 of [ITU-T J.205]).
+
+The ACF should allow that, in the case of the IBB application model, IBB applications could be launched in any of the conditions described in Table 4.
+
+**Table 4 – IBB application launching conditions**
+
+| Launching condition                                                        | Stand-alone IBB application | Service associated IBB application |                      |
+|----------------------------------------------------------------------------|-----------------------------|------------------------------------|----------------------|
+|                                                                            |                             | Service exclusive                  | Service shared       |
+| Signalled to be auto-started in the currently selected IBB DTV service     | Launch <sup>a)</sup>        | Launch                             | Launch               |
+| Started by an already existing application using a middleware-provided API | Launch <sup>b)</sup>        | Launch <sup>b)</sup>               | Launch <sup>b)</sup> |
+| User started from the AppCatUI                                             | Launch                      | Launch                             | Launch               |
+
+<sup>a)</sup> In some cases, the launch of stand-alone IBB applications may be allowed for resident and/or installable applications. Applications dedicated for an emergency situation are an example of this case.
+
+<sup>b)</sup> In some cases, the launched application may not be allowed to keep the original application's context.
+
+IBB application termination should occur according to the conditions described in Table 5.
+
+**Table 5 – IBB application termination conditions**
+
+| Launching condition                                                                                             | Stand-alone IBB application                                       | Service associated IBB application |                |
+|-----------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------|------------------------------------|----------------|
+|                                                                                                                 |                                                                   | Service exclusive                  | Service shared |
+| Signalled to be KILLed or DESTROYed in the current selected IBB DTV service                                     | –                                                                 | Terminate                          | Terminate      |
+| Has been removed from the service's AIT                                                                         | –                                                                 | Terminate                          | Terminate      |
+| Stopped by another service associated IBB application (with proper permissions) using a middleware-provided API | –                                                                 | Terminate                          | Terminate      |
+| User stopped from the AppCatUI                                                                                  | Kill, whenever the application has been started from the AppCatUI |                                    |                |
+
+**Table 5 – IBB application termination conditions**
+
+| Launching condition                                                                 | Stand-alone IBB application | Service associated IBB application |                                                                                                                              |
+|-------------------------------------------------------------------------------------|-----------------------------|------------------------------------|------------------------------------------------------------------------------------------------------------------------------|
+|                                                                                     |                             | Service exclusive                  | Service shared                                                                                                               |
+| Service change occurs                                                               | –                           | Terminate                          | Terminate if conditions to keep the application alive are not met (application is not signalled in the new selected service) |
+| The IBB application terminates itself by calling a specific middleware-provided API | Terminate                   |                                    |                                                                                                                              |
+| An exception is raised and it is not handled by the IBB application                 | Terminate                   |                                    |                                                                                                                              |
+| The IBB DTV receiver runs out of enough resources to execute the IBB application    | Terminate                   |                                    |                                                                                                                              |
+
+Most of these mechanisms are already defined in [b-MHP], [b-GINGA-J], [b-GINGA-NCL] and [b-ARIB B.23]. In such cases, the pre-existing definitions are adopted.
+
+The ACF framework should support two or more IBB applications to be executed simultaneously. The AppCatUI must allow the user to bring the different applications to focus. Additionally, the ACF must grant the isolation between the running applications within its scope, but the IBB DTV receiver must provide isolation from other platform applications. This is important for stand-alone IBB applications that may not be aware of other native applications executed in the system.
+
+The ACF must be capable of handling service associated and stand-alone IBB applications at the same time.
+
+In the case of service associated IBB applications, it should be possible for the ACF to handle both service exclusive and service shared IBB applications.
+
+## 8.6 The application catalogue user interface (AppCatUI)
+
+The application catalogue user interface (AppCatUI), see Figure 8-3, is a functionality provided by the IBB DTV receiver intended for listing the available applications that can be launched by the user (FR-ACF-10 of [ITU-T J.205]). This concept is already present in DTV middleware standards such as [b-GINGA-J], [b-GINGA-NCL] or [b-MHP]. As an extension to the concepts in current DTV middleware specifications, the AppCatUI in the ACF must include the following functionalities:
+
+- Listing applications available to the user including:
+  - Conventional DTV services' applications that can be launched by the user. For example: signalled with AIT control codes AUTOSTART ([b-MHP], [b-GINGA-Data Transmission]), PRESENT ([b-MHP], [b-GINGA-Data Transmission]), STORED ([b-GINGA-Data Transmission]), REMOTE ([b-GINGA-Data Transmission]), UNBOUND ([b-GINGA-Data Transmission]), etc., and the visibility flag enabled ([b-GINGA-Data Transmission], [b-MHP]).
+  - Service associated IBB applications meeting the same signalling requirements as for conventional DTV services' applications.
+  - Stand-alone IBB applications (both installed IBB applications and resident IBB applications).
+
+- Retrieving remote application catalogues from an application repository.
+- Allow the end user to launch any listed application.
+- Allow the end user to bring to focus any listed application already in execution.
+- Allow the end user to terminate any listed application already in execution.
+- Provide access to the available user-oriented application metadata (such as application name, provider, version, etc.).
+
+The list ordering of the applications in the AppCatUI should change dynamically, according to the following priority rules:
+
+- Firstly, the service associated IBB applications signalled within the IBB DTV service selected at current time must be shown differentiated and highlighted, so the user can clearly identify that such applications are part of the IBB DTV service content. Additionally, the user interface design should grant quicker access to these applications.
+- Secondly, the ordering within service associated IBB applications is defined by the order in which applications are declared in the IBB DTV service (e.g., AIT).
+- Stand-alone IBB applications available through the current selected IBB DTV service's application repository should be listed in second priority order. In this case, the installed applications should be listed first.
+- Finally, the stand-alone IBB applications installed in the IBB DTV receiver are listed, following the items above.
+
+![Figure 8-3 – Example of AppCatUI. The image shows a screenshot of a user interface for an application catalog. It features a vertical list of application entries. Each entry includes an 'Application icon' on the left, followed by metadata: '<Application name>', 'Status', '<Provider>', 'Version: <version>', '<Service associated | Stand-alone>', 'Source: <Service | Portal | Repository | Installed | HAN>', and '<Signed | Unsigned>'. Below the metadata is a '<Description>' field. The bottom of the screen contains a control panel with buttons for 'Launch', 'Kill', 'Focus' (grouped as 'Application control'), 'Buy', 'Install', 'Update', 'Uninstall', 'Share' (grouped as 'Installable application management'), and a status bar showing 'Available space: <## MB> External USB: <## MB>'.](a2c9fe78d22304889baddc26f4329ddf_img.jpg)
+
+Figure 8-3 – Example of AppCatUI. The image shows a screenshot of a user interface for an application catalog. It features a vertical list of application entries. Each entry includes an 'Application icon' on the left, followed by metadata: '', 'Status', '', 'Version: ', '', 'Source: ', and ''. Below the metadata is a '' field. The bottom of the screen contains a control panel with buttons for 'Launch', 'Kill', 'Focus' (grouped as 'Application control'), 'Buy', 'Install', 'Update', 'Uninstall', 'Share' (grouped as 'Installable application management'), and a status bar showing 'Available space: <## MB> External USB: <## MB>'.
+
+J.206(13)\_F8-3
+
+Figure 8-3 – Example of AppCatUI
+
+## 8.7 IBB installable application management
+
+IBB installable applications can be stored in the IBB DTV receiver. As described in clause 8.3, item d, installation could occur when indicated by the IBB DTV service provider or by a specific action from the user.
+
+IBB applications can be installed in the IBB DTV receiver's persistent storage in the following ways:
+
+- Automatically installed: when signalled in a selected DTV service, a special signalling must be used in order to indicate that the application is to be installed in the receiver.
+
+Such a mechanism is provided by the AIT's UNBOUND control code in [b-GINGA-Data Transmission]. Automatically installed applications may require confirmation from the end user.
+
+Other equivalent mechanisms can be used as well, especially when storing applications is used as a caching strategy. In this case, user confirmation is not required.
+
+- User installed application. In this case, the IBB installable application's origin can be:
+
+- a server reached through the broadband channel
+- an application repository
+- another device in the HAN
+- a pluggable storage device (such as USB stick or external hard disk), etc.
+
+In the case of the application repository, the installable application manager should retrieve a remote application catalogue from the application repository.
+
+In the case of another device in the HAN or pluggable storage device (such as a USB stick or external hard disk), the device should be inspected looking for AIPs and a list should be presented to the end user in order to choose which IBB applications to install.
+
+In all cases, for a user-installed application, the IBB application should be installed from an AIP.
+
+### 8.7.1 Rules for IBB installable application storage management
+
+The following rules for application storage management must be considered by the IBB DTV service provider and the IBB DTV receiver for handling IBB installable applications:
+
+- Under limited storage space conditions, in the case of automatically installed applications, the least recently used algorithm may be used for uninstalling IBB applications. If a user's confirmation was requested for installation, uninstalling would require another user's confirmation.
+- In the case of user installed applications, IBB DTV receivers should provide a mechanism for the user being able to request the uninstalling of the IBB application.
+- In both cases, when installing (updating to) a newer version of an IBB application, the older version must be removed.
+
+### 8.7.2 IBB application updating
+
+The IBB installable application management must also support the following application update mechanism:
+
+- Periodically checking the installation source (i.e., the application repository from which the application has been downloaded) looking for recent versions of the already installed applications.
+- Whenever a newer version of the application is being signalled in the selected IBB DTV service, the IBB DTV receiver should try to update it.
+
+- If the original application is signed by the IBB application provider, a new IBB application should be signed also by the same IBB application provider.
+
+If the user's confirmation was requested for installation, the updating of the IBB application will require another user's confirmation.
+
+#### 8.7.3 IBB application update criteria
+
+In order to identify that an installed IBB application requires updating, the IBB DTV receiver should use the following criteria:
+
+- match the Application\_ID and Application\_Provider\_ID;
+- ensure the application version field of the installed application should be lower than the version field of the IBB application being signalled or listed in the remote application catalogue retrieved from the application repository.
+
+#### 8.7.4 Organization of IBB installable applications (optional)
+
+The IBB installable application management subsystem may allow the end user to arrange the installed IBB applications in a customizable hierarchical directory structure or in groups. This may become a usability issue that implementations adherent to this Recommendation may need to address.
+
+### 8.7.5 IBB resident application updating (optional)
+
+The ACF is also intended to manage resident applications, which are embedded in the IBB DTV receiver and controlled by the manufacturer. Resident applications may also be subjected to updates. Manufacturers may adopt the same update mechanism provided for IBB installable applications, (e.g., defining an Internet application repository for making available new versions of the resident applications).
+
+Other mechanisms, such as firmware updates, may be applicable as well, but in these cases, the procedures to be used are not within the scope of this Recommendation.
+
+#### 8.7.6 Storage organization for IBB applications
+
+Figure 8-4 defines a high-level division of the IBB DTV receiver's storage, and highlights how this storage is managed:
+
+- ROM/FIRMWARE: This read-only memory stores the resident IBB applications. This is usually managed by the IBB DTV receiver manufacturer and usually updated by firmware updates.
+- PERSISTENT READ/WRITE: This is general purpose non-volatile memory:
+  - ACF managed storage: The ACF uses this area to store the automatically installed IBB application components and, optionally, do caching of service bounded IBB application components.
+  - User managed storage: This is the area used to store the user installed IBB applications.
+  - Application managed storage: This area is reserved for the applications to store files, settings and any other resource that may have been downloaded or created by the IBB application.
+- RAM FILE SYSTEM: This is a volatile storage used to temporarily store any data. This is mainly used for in-progress downloads of IBB application components.
+
+![Diagram of IBB DTV receiver's storage organization showing three storage cylinders: ROM/FIRMWARE, PERSISTENT READ/WRITE, and RAM FILE SYSTEM. A legend at the bottom identifies management types: Manufacturer managed (yellow), ACF managed (blue), User managed (green), and Application managed (orange).](cbdfdade780e677eb1c1aef3081ce9ef_img.jpg)
+
+The diagram illustrates the storage organization of an IBB DTV receiver, consisting of three main storage areas represented as cylinders:
+
+- ROM/FIRMWARE (Grey cylinder):** Contains **Resident IBB applications** (Yellow, Manufacturer managed).
+- PERSISTENT READ/WRITE (Pink cylinder):** Contains the following layers from top to bottom:
+  - Application downloaded resources** (Orange, Application managed)
+  - Custom settings** (Orange, Application managed)
+  - Cached service bounded IBB application components** (Blue, ACF managed)
+  - Automatically installed IBB applications** (Blue, ACF managed)
+  - User installed IBB applications** (Green, User managed)
+- RAM FILE SYSTEM (Purple cylinder):** Contains **In progress downloads of IBB application components** (Blue, ACF managed).
+
+**Legend:**
+
+- Yellow square: Manufacturer managed
+- Blue square: ACF managed
+- Green square: User managed
+- Orange square: Application managed
+
+J.206(13)\_F8-4
+
+Diagram of IBB DTV receiver's storage organization showing three storage cylinders: ROM/FIRMWARE, PERSISTENT READ/WRITE, and RAM FILE SYSTEM. A legend at the bottom identifies management types: Manufacturer managed (yellow), ACF managed (blue), User managed (green), and Application managed (orange).
+
+**Figure 8-4 – IBB DTV receiver's storage organization**
+
+## 8.8 Internet application repository
+
+Internet application repositories are Internet servers intended to distribute applications for on-demand installation (FR-ACF-06 of [ITU-T J.205]). Each Internet application repository must export a remote application catalogue. This catalogue is queried by the IBB DTV receiver in order to:
+
+- Allow the end user to browse and search through the applications available in the Internet application repository, using the application catalogue user interface (FR-ACF-04 of [ITU-T J.205]).
+  - The application catalogue user interface should display application information details such as name, a brief description, icon, screen shots, price, version, required storage space, vendor, etc. This information is contained in the remote application catalogue.
+- Allow the end user to choose applications to install in the IBB DTV receiver. In this case, the IBB DTV receiver would download an application installation package from the Internet application repository and install it.
+
+### **8.8.1 Internet application repository user account**
+
+Some Internet application repositories may require a user account to:
+
+- query the remote application catalogue and/or
+- download an application.
+
+In these cases, a session must be established using the authentication protocol.
+
+### **8.8.2 Application installation package (AIP) downloading protocol**
+
+For downloading the AIP, the HTTP1.1 or HTTPS1.1 protocols must be used. The downloaded AIP must be stored in the IBB DTV receiver's persistent storage in a special area not accessible by the applications.
+
+Once the AIP downloading has been completed, the IBB DTV receiver should install the application, making it ready for execution upon user request.
+
+Once the IBB application is installed, the IBB DTV receiver may choose to delete the AIP from its persistent storage or keep it for further sharing with other devices in the HAN (this second option is not a mandatory requirement but a highly recommended feature).
+
+### **8.8.3 Internet application repository application purchase (optional)**
+
+Some content may not be free; in this case, the end user should be able to purchase the application with credits previously charged to his/her user account. Once the payment is confirmed, the application should become available for installing.
+
+The ACF contemplates a user account identification mechanism that can be used as the basis for building custom payments and credit handling mechanisms at the IBB application level.
+
+## **8.9 Ensuring DTV service integrity and IBB application permissions policy**
+
+As previously defined, a DTV service is a unit for delivering audio-visual-interactive content to end users, and constitutes an editorially consistent whole.
+
+It is a requirement for the ACF to ensure that the DTV service is always consistent with the IBB DTV service provider editorial rules (FR-ACF-14 of [ITU-T J.205]).
+
+The IBB DTV receiver must implement a different handling for service associated IBB applications and stand-alone IBB applications.
+
+### **Service associated IBB applications**
+
+Service associated IBB applications are allowed to be displayed combined with other services' contents (audio, video, closed caption and other interactive content) belonging to the same DTV service and interact with them (the rationale behind this is that service associated IBB applications are part of the same editorial unit). In this case, application authentication and permission rules such as those defined by [b-MHP] or [b-JAVADTV] must be applied.
+
+### **Stand-alone IBB applications**
+
+When executing stand-alone IBB applications or IBB applications from other service providers with no explicit permissions granted from the currently selected IBB DTV service provider, the IBB DTV receiver can take four different actions:
+
+- the service exhibition can be stopped (video hidden, audio muted and any other service content hidden) as defined in [EBU-req]; or
+- the screen can be divided in such a way that the IBB DTV service content exhibition and the IBB application are displayed in different and non-overlapping regions. In these cases, separation of the IBB application and the IBB DTV service content must be very clear to the end user; or
+
+- the IBB application can be displayed on a secondary screen device associated with the IBB DTV receiver; or
+- the IBB application may not be allowed to use an IBB DTV receiver's resource that the DTV service is using.
+
+The above actions that can be taken by the IBB DTV receiver should follow the information that describes the IBB DTV service provider's intention for exhibition of stand-alone IBB applications, which may be delivered through the DTV service channel or should follow a predefined system design rule.
+
+IBB DTV service providers may desire to explicitly grant permissions to specific stand-alone IBB applications (such as installed IBB applications) or applications associated with different services in order behave as if they were part of the service. To achieve this, stand-alone IBB applications must be distributed with a signature from the IBB DTV service provider in the AIP.
+
+In this case, stand-alone IBB applications would be allowed to:
+
+- overlay over another service's contents such as the service's video or the other service's applications;
+- manage or change service exhibition such as video control (video freeze, stop, scaling, etc.), audio control (audio stop, volume level change, etc.) and starting or stopping any other service component (subtitles, closed captions, alternate audio, alternate video, etc.); and
+- interact, communicate or control (start/pause/destroy) other IBB applications in the DTV service.
+
+A stand-alone IBB application can be distributed with signatures from different IBB DTV service providers. In this case, IBB DTV receivers should grant those applications the same execution rights as IBB applications associated with each one of the IBB DTV services delivered by the signing IBB DTV service providers.
+
+![Diagram of a stand-alone IBB application structure showing Code, Resources, Metadata, Control, and User settings, with signatures from multiple service providers (A, B, C) and the application provider.](705ee99c3c44fd2a1ea6a3348ce8878f_img.jpg)
+
+The diagram illustrates the structure of a stand-alone IBB application. At the top, a box labeled "Stand-alone IBB application" contains five sub-components: "Code", "Resources", "Metadata", "Control", and "User settings". Below this, a large box contains the "Application provider's signature" and three boxes representing signatures from different service providers: "IBB DTV service provider A's signature", "IBB DTV service provider B's signature", and "IBB DTV service provider C's signature". At the bottom, a box labeled "Application installation package" is shown. A small label "J.206(13)\_F8-5" is visible to the right of the diagram.
+
+Diagram of a stand-alone IBB application structure showing Code, Resources, Metadata, Control, and User settings, with signatures from multiple service providers (A, B, C) and the application provider.
+
+**Figure 8-5 – Sample of distribution of stand-alone IBB applications signed by multiple IBB DTV service providers**
+
+In Figure 8-5 the given stand-alone IBB application must be granted the same executions rights as service associated IBB applications whenever any IBB DTV service from IBB DTV service providers A, B or C are selected by the IBB DTV receiver.
+
+## **8.10 Ensure user privacy and user data protection**
+
+Authentication mechanism and permissions policies should be considered for IBB applications in order to protect user privacy and data (FR-ACF-15 of [ITU-T J.205]). Only IBB applications signed by IBB application providers will be allowed to:
+
+- access user settings;
+- access the IBB DTV receiver's persistent storage;
+- access other devices in the HAN;
+- use an Internet connection or establish a connection with another device outside the IBB DTV receiver;
+- access resources from the broadband channel;
+- communicate or interact with other IBB applications.
+
+IBB applications not signed by their IBB application provider are strictly restricted to local execution, inside the IBB DTV receiver. It is strictly prohibited for them to communicate with other external entities through the broadband or HAN networks.
+
+## **8.11 User account management**
+
+The user account is to be associated with:
+
+- IBB application's custom user settings stored in an IBB DTV receiver device, other devices in the HAN or servers reached through the broadband channel;
+- access rights to a set of applications and services.
+
+At the application level, they can be associated with:
+
+- a credit account or payment information for accessing non-free content.
+- Other accounts used in Internet services (such as e-mail, social networks, instant messaging, voice and video calls, etc.).
+
+Many devices are usually shared among several users (e.g., a TV set shared by the members of a family). On the other hand, some devices are mostly used by a single person (tablet, mobile phone, etc.). The ACF must be aware of this and support the ability to handle several user accounts in a single device.
+
+From the IBB application viewpoint, it should only be possible to access resources and settings exclusively associated with the currently logged in account.
+
+#### **8.11.1 User identity**
+
+The user identity is a value (exposed as a user setting) that defines a unique universal identifier for the end user. This value must be used to unequivocally identify the user with any other entity within the system (i.e., application repository, any custom Internet service accessed by applications or even HAN devices). See Figure 8-6.
+
+![Diagram illustrating the user settings and resources associated by the user identity value across different entities connected via a broadband channel.](11edb7fcedf09ac6a817f8d7b8c61eec_img.jpg)
+
+The diagram shows a central vertical bar labeled "Broadband channel". To its left, three entities are stacked vertically, connected by double-headed arrows:
+ 
+
+- IBB DTV receiver**: Contains a "User account" box with:
+  - Identity
+  - IBB system settings
+  - General settings
+  - Application settings
+  - Preferred application list
+  - Resources
+- HAN**: A central connecting entity.
+- HAN device**: Contains a "User account" box with:
+  - Identity
+  - IBB system settings
+  - General settings
+  - Application settings
+  - Preferred application list
+  - Resources
+
+ To the right of the broadband channel, three entities are stacked vertically, each connected to the channel by a double-headed arrow:
+ 
+
+- Application portal**: Contains a "User account" box with:
+  - Identity
+  - Application portal specific settings
+  - Credits
+- HBB application Internet repository**: Contains a "User account" box with:
+  - Identity
+  - Application Internet repository settings
+  - Credits
+- Custom Internet service**: Contains a "User account" box with:
+  - Identity
+  - Custom Internet service specific settings
+  - Credits
+  - Resources
+
+ A small label "J.206(13)\_FB-6" is in the bottom right corner.
+
+Diagram illustrating the user settings and resources associated by the user identity value across different entities connected via a broadband channel.
+
+**Figure 8-6 – User settings and resources associated by the user identity value**
+
+A user authentication protocol should be used in order to establish a secure session with a remote entity such as an application repository, a custom Internet service or a HAN device.
+
+Once the secure session is established, IBB applications will be able to access remote stored settings, resources and other IBB applications.
+
+#### 8.11.2 Accessing settings and properties
+
+Only two kinds of settings are considered in this specification:
+
+- **IBB application settings**: This refers to a set of settings that constitute part of this specification and must be supported by any ACF compliant solution. Usually, these settings are stored in the IBB DTV receiver and can be shared among HAN devices using the HAN sharing settings protocol. The scope of these settings may be system wide: applied to all the IBB DTV receiver's users; or specific user settings; a different value must be stored for each user account.
+- **Custom settings**: Any other user settings not in the IBB application settings must be considered application settings (or custom settings). Applications may store any custom setting in the IBB DTV receiver indicating its scope: whether it is a system wide setting or a user account setting. Additionally, applications may retrieve custom settings from other HAN devices, using the HAN user setting sharing protocol, or from custom Internet service entities using the protocol for querying remote user settings.
+
+In every case, before retrieving user account settings from another device or entity, a secure session must be established for the user account.
+
+In every case, settings are exposed to IBB applications as a pair of strings (property\_name, value) in a table, indexed by the property\_name.
+
+#### 8.11.3 Accessing resources
+
+Resources are considered to be any file or stream accessed by any given IBB application. Some resources may require some kind of access restriction, and the user identity must be verified for granting access to such resources:
+
+- In the case of external resources in the application repository, custom Internet services or HAN devices, the user authentication protocol must be used to establish a secure session so the IBB application can access non-public resources from these types of sources. This specification does not define how these resources are to be handled internally by these remote entities.
+- In the case of resources stored in the IBB DTV receiver in the user account's exclusive persistent storage, access must be granted only to the resources stored in the exclusive persistent storage of the user account currently logged in the receiver. The same is required for saving resources or any other file in this storage space.
+
+Verification of user identity is not required to access or store resources in the IBB DTV receiver's general persistent storage.
+
+#### 8.11.4 Accessing non-public applications and the remote application catalogue
+
+Some IBB applications in application repositories can be non-public and require user authentication for listing or downloading.
+
+The ACF must establish a secure session with the application repositories, using the user authentication protocol for gaining access to this kind of non-public content.
+
+## 8.12 Location awareness (optional)
+
+IBB applications can retrieve information about the geographical location of the IBB DTV receiver through the properties defined in the IBB application settings (FR-ACF-19 of [ITU-T J.205]).
+
+## 8.13 DTV service synchronization (stream events)
+
+The ACF must follow recommendations and mechanisms from [b-MHP], [b-GINGA-NCL] and [b-GINGA-J] for providing a functionality that allows the synchronization of IBB applications with the IBB DTV service content (FR-ACF-22 of [ITU-T J.205]).
+
+## 8.14 Media content streaming (optional)
+
+The IBB DTV receiver can provide a video capture capability from different sources such as:
+
+- HAN device such as a connected webcam, tablet, smart phone, etc.
+- A video camera and microphone plugged or embedded into the IBB DTV receiver.
+
+Such a capability can be exposed to IBB applications as an API extension to [ITU-T J.200]. This would allow implementing IBB applications, such as VOIP and video calls, capable of capturing such input streams and forwarding them to external hosts (FR-ACF-26 of [ITU-T J.205]).
+
+Stream playback capabilities can also be exposed to the interactive content and applications as API extensions to [ITU-T J.200], allowing the implementation of client applications and players for services such as Internet multimedia content providers and content aggregators.
+
+## 8.15 Cryptographic API
+
+An API for cryptography and certificate management, such as defined in [b-ITU-T J.202] must be made available to IBB applications (FR-ACF-27 of [ITU-T J.205]). These also should include an API for accessing functionalities available in devices such as smart cards or cryptographic USB tokens.
+
+## **8.16 Persistent storage**
+
+A mechanism such as defined in [b-ITU-T J.202] must be used for IBB applications having read/write access to the IBB DTV receiver's persistent storage (FR-ACF-24 of [ITU-T J.205]).
+
+### **8.16.1 Resource downloading**
+
+By combining the usage of an API for remote resource access and persistent storage access, an application can download and store resources in the IBB DTV receiver's persistent storage.
+
+# Bibliography
+
+- [b-ITU-T H.761] Recommendation ITU-T H.761 (2009), *Nested Context Language (NCL) and Ginga-NCL for IPTV services.*
+- [b-ITU-T J.201] Recommendation ITU-T J.201 (2009), *Harmonization of declarative content format for interactive television applications.*
+- [b-ITU-T J.202] Recommendation ITU-T J.202 (2010), *Harmonization of procedural content formats for interactive TV applications.*
+- [b-ITU-R BT.1888] Recommendation ITU-R BT.1888 (2011), *Basic elements of file-based broadcasting systems.*
+- [b-GINGA-Data Coding] ABNT NBR 15606-1:2007, *Digital terrestrial television – Data coding and transmission specification for digital broadcasting – Part 1: Data coding specification.*
+- [b-GINGA-NCL] ABNT NBR 15606-2:2007, *Digital terrestrial television – Data coding and transmission specification for digital broadcasting – Part 2: Ginga-NCL for fixed and mobile receivers – XML application language for application coding.*
+- [b-GINGA-Data Transmission] ABNT NBR 15606-3:2007, *Digital terrestrial television – Data coding and transmission specification for digital broadcasting – Part 3: Data transmission specification.*
+- [b-GINGA-J] ABNT NBR 15606-4:2010, *Digital terrestrial television – Data coding and transmission specification for digital broadcasting – Part 4: Ginga-J – The environment for the execution of procedural applications.*  
+<<http://www.tvdi.inf.br/site/artigos/Normas%20ABNT/15606-4-Middleware.pdf>>
+- [b-JAVADTV] ABNT NBR 15606-6:2010, *Digital terrestrial television – Data coding and transmission specification for digital broadcasting – Part 6: Java DTV 1.3.*
+- [b-ARIB B.23] ARIB STD-B23 V1.1 (2004), *Application Execution Engine Platform for Digital Broad Casting.*  
+<[http://www.arib.or.jp/english/html/overview/archives/br/ARIB\\_STD-B23\\_v1.1\\_E1.pdf](http://www.arib.or.jp/english/html/overview/archives/br/ARIB_STD-B23_v1.1_E1.pdf)>
+- [b-ARIB B.24] ARIB STD-B24 V5.1 (2007), *Data Coding and Transmission Specifications for Digital Broadcasting.*  
+<[http://www.arib.or.jp/english/html/overview/archives/br/ARIB\\_STD-B24-1\\_v5.1\\_E1.pdf](http://www.arib.or.jp/english/html/overview/archives/br/ARIB_STD-B24-1_v5.1_E1.pdf)>
+- [b-ATSC] ATSC A/101 (2010), *Advanced Common Application Platform Certification Mark (ACAP).*  
+<<http://www.atsc.org/cms/index.php/policies/details/194-atsc-standard-a101-advanced-common-application-platform-certification-mark>>
+- [b-ECMAScript] Standard ECMA-262 (2000), 3rd Edition, *ECMAScript Language Specification.*
+- [b-ETSI ES 202 184] ETSI ES 202 184 V.1.1.1 (2004), *MHEG-5 Broadcast Profile.*  
+<[http://www.etsi.org/deliver/etsi\\_es/202100\\_202199/202184/01.01.01\\_50/es\\_202184v01010101m.pdf](http://www.etsi.org/deliver/etsi_es/202100_202199/202184/01.01.01_50/es_202184v01010101m.pdf)>
+- [b-MHP] ETSI TS 102 727 v1.1.1 (2010), *Digital Video Broadcasting (DVB); Multimedia Home Platform (MHP) Specification 1.2.2.*  
+[http://www.etsi.org/deliver/etsi\\_ts/102700\\_102799/102727/01.01.01\\_60/ts\\_102727v01010101p.pdf](http://www.etsi.org/deliver/etsi_ts/102700_102799/102727/01.01.01_60/ts_102727v01010101p.pdf)
+
+- [b-ETSI TS 102 728] ETSI TS 102 728 V1.1.1 (2010), *Digital Video Broadcasting (DVB); Globally Executable MHP (GEM) Specification 1.2.2 (including IPTV)*.  
+[<http://www.etsi.org/deliver/etsi\\_ts/102700\\_102799/102728/01.01.01\\_60/ts\\_102728v010101p.pdf>](http://www.etsi.org/deliver/etsi_ts/102700_102799/102728/01.01.01_60/ts_102728v010101p.pdf)
+- [b-IETF RFC 3926] IETF RFC 3926 (2004), *FLUTE – File Delivery over Unidirectional Transport*.  
+[<http://www.rfc-base.org/rfc-3926.html>](http://www.rfc-base.org/rfc-3926.html)
+- [b-IETF RFC 4918] IETF RFC 4918 (2007), *HTTP Extensions for Web Distributed Authoring and Versioning (WebDAV)*.  
+[<http://www.ietf.org/rfc/rfc4918.txt>](http://www.ietf.org/rfc/rfc4918.txt)
+- [b-PBP] Java Community Process (2006), *JSR 217 Personal Basis Profile 1.1*.  
+[<http://jcp.org/en/jsr/detail?id=217>](http://jcp.org/en/jsr/detail?id=217)
+- [b-CDC] JAVA Community Process (2006), *JSR 218: Connected Device Configuration (CDC) 1.1*.  
+[<http://jcp.org/en/jsr/detail?id=218>](http://jcp.org/en/jsr/detail?id=218)
+- [b-FP] JAVA Community Process (2006), *JSR 219: Foundation Profile 1.1*.  
+[<http://jcp.org/en/jsr/detail?id=219>](http://jcp.org/en/jsr/detail?id=219)
+- [b-JAVATV] JAVA Community Process (2008), *JSR 927: Java™ TV API 1.1*.  
+[<http://jcp.org/en/jsr/summary?id=927>](http://jcp.org/en/jsr/summary?id=927)
+- [b-EBU-req] Kozamernik, F. (2009), *HBB television Hybrid Broadcast Broadband TV – EBU Requirements*. Joint EBU/ETSI Workshop, 9 September 2009.  
+[<http://tech.ebu.ch/docs/events/hbbworkshop09/presentations/hbbworkshop09\\_kozamernik.pdf>](http://tech.ebu.ch/docs/events/hbbworkshop09/presentations/hbbworkshop09_kozamernik.pdf)
+- [b-OCAP] OCAP 1.0.1 (2007), *OCAP 1.0.1 Profile*.  
+[<http://www.cablelabs.com/specifications/OC-SP-OCAP1.0.1-070824.pdf>](http://www.cablelabs.com/specifications/OC-SP-OCAP1.0.1-070824.pdf)
+- [b-W3C HTML] W3C Recommendation (1999), *HTML 4.01 Specification*.  
+[<http://www.w3.org/TR/1999/REC-html401-19991224>](http://www.w3.org/TR/1999/REC-html401-19991224)
+
+
+
+## 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.212**
+
+(11/2006)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Interactive systems for digital television distribution
+
+---
+
+**Downstream external Physical layer interface  
+for modular cable modem termination systems**
+
+ITU-T Recommendation J.212
+
+
+
+# **ITU-T Recommendation J.212**
+
+# **Downstream external Physical layer interface for modular cable modem termination systems**
+
+## **Summary**
+
+This Recommendation defines an interface known as the Downstream External PHY Interface (DEPI) and associated protocol requirements for the transport of downstream user data between the "M-CMTS Core" and the EQAM. It describes the characteristics of the DEPI interface, provides requirements that must be met by the M-CMTS Core and the EQAM, and also describes various aspects of technical issues that are involved in the implementation and deployment of a DOCSIS system using the M-CMTS architecture.
+
+## **Source**
+
+ITU-T Recommendation J.212 was approved on 29 November 2006 by ITU-T Study Group 9 (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, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2007
+
+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  |
+| 2.1 | Normative references.....                             | 2  |
+| 2.2 | Informative references.....                           | 2  |
+| 2.3 | Reference acquisition .....                           | 3  |
+| 3   | Terms and definitions .....                           | 3  |
+| 4   | Abbreviations, acronyms and conventions.....          | 6  |
+| 4.1 | Abbreviations and acronyms .....                      | 6  |
+| 4.2 | Conventions .....                                     | 8  |
+| 5   | Technical overview.....                               | 9  |
+| 5.1 | System architecture .....                             | 9  |
+| 5.2 | Bonding services model .....                          | 13 |
+| 5.3 | Multiple services model .....                         | 13 |
+| 6   | DEPI architecture.....                                | 14 |
+| 6.1 | DEPI Data Path.....                                   | 14 |
+| 6.2 | Networking considerations.....                        | 18 |
+| 6.3 | System timing considerations.....                     | 20 |
+| 7   | DEPI control plane .....                              | 20 |
+| 7.1 | Topology.....                                         | 21 |
+| 7.2 | Addressing.....                                       | 21 |
+| 7.3 | Control message format.....                           | 23 |
+| 7.4 | Signalling.....                                       | 27 |
+| 7.5 | AVP definitions .....                                 | 33 |
+| 8   | DEPI forwarding plane .....                           | 47 |
+| 8.1 | L2TPv3 transport packet format.....                   | 47 |
+| 8.2 | DOCSIS MPT mode.....                                  | 50 |
+| 8.3 | PSP mode.....                                         | 51 |
+| 8.4 | DEPI latency measurement (DLM) sublayer header.....   | 52 |
+| 8.5 | M-CMTS core output rate .....                         | 53 |
+|     | Annex A – DEPI MTU .....                              | 54 |
+| A.1 | L2TPv3 lower layer payload size .....                 | 54 |
+| A.2 | Maximum frame size for DEPI .....                     | 54 |
+| A.3 | Path MTU discovery.....                               | 55 |
+|     | Annex B – Parameters and constants .....              | 55 |
+|     | Appendix I – DEPI and DOCSIS system performance ..... | 56 |
+| I.1 | Introduction .....                                    | 56 |
+| I.2 | Round-trip time and performance .....                 | 56 |
+
+|                                                                     | <b>Page</b>                                        |
+|---------------------------------------------------------------------|----------------------------------------------------|
+| I.3                                                                 | Elements of round-trip time..... 56                |
+| I.4                                                                 | CIN characteristics ..... 58                       |
+| I.5                                                                 | Queueing delays in network elements..... 59        |
+| I.6                                                                 | Traffic prioritization and network delays ..... 60 |
+| I.7                                                                 | Queue persistence in a DEPI flow..... 60           |
+| I.8                                                                 | PSP mode..... 62                                   |
+| Appendix II – Early adoption and evolving use of EQAM devices ..... | 63                                                 |
+| II.1                                                                | EQAM development: Category A (no DTI)..... 63      |
+| II.2                                                                | EQAM development: Category B (with DTI)..... 64    |
+| II.3                                                                | Possible M-CMTS feature phasing ..... 64           |
+| II.4                                                                | Optional UDP layer ..... 65                        |
+
+# **Downstream external Physical layer interface for modular cable modem termination systems**
+
+# **1 Scope**
+
+This Recommendation is part of the DOCSIS<sup>®</sup> family of Recommendations that define a Modular Cable Modem Termination System (M-CMTS<sup>™</sup>) architecture for head-end components that comply with DOCSIS.
+
+The DOCSIS Recommendations [J.122] define the requirements for the two fundamental components that comprise a high-speed data-over-cable system: the cable modem (CM) and the cable modem termination system (CMTS). The M-CMTS architecture was designed as an extension to the DOCSIS Recommendations to allow for flexibility and independent scaling of certain CMTS functions, and to allow operators to more efficiently use available network resources.
+
+One of the key elements of the M-CMTS architecture is the separation of the downstream physical layer QAM modulation and up-conversion functions from the CMTS, and the placement of that functionality into an "Edge-QAM" (EQAM) device. This separation allows for the development of EQAM products that support both video and DOCSIS, which in turn allows operators to use the same network resources to support multiple types of services such as data, voice and video.
+
+This Recommendation defines an interface known as the Downstream External PHY Interface (DEPI) and associated protocol requirements for the transport of downstream user data between the "M-CMTS Core" and the EQAM. It describes the characteristics of the DEPI interface, provides requirements that must be met by the M-CMTS Core and the EQAM, and also describes various aspects of technical issues that are involved in the implementation and deployment of a DOCSIS system using the M-CMTS architecture.
+
+Two different master clock frequency options are available within the M-CMTS architecture. The first option, a 10.24 MHz master clock is used in the Americas, Europe and other regions. The second option, a 9.216 MHz master clock is used in Japan. Compliance with this Recommendation requires compliance with the one or the other of these implementations, not with both. It is not required that equipment built to one option shall interoperate with equipment built to the other.
+
+A list of the documents in the Modular CMTS Interface Recommendations family is provided below.
+
+| <b>Designation</b> | <b>Title</b>                                                                                                              |
+|--------------------|---------------------------------------------------------------------------------------------------------------------------|
+| J.212              | Downstream External PHY Interface                                                                                         |
+| J.211              | DOCSIS Timing Interface                                                                                                   |
+| CM-SP-ERMI         | Edge Resource Manager Interface, CM-SP-ERMI-I02-051209, 9 December 2005, Cable Television Laboratories, Inc.              |
+| CM-SP-M-OSSI       | M-CMTS Operations Support System Interface, CM-SP-M-OSSI-I02-051209, 9 December 2005, Cable Television Laboratories, Inc. |
+
+# 2 References
+
+## 2.1 Normative 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.
+
+- [H.222.0] ITU-T Recommendation H.222.0 (2006) | ISO/IEC 13818-1:2007, *Information technology – Generic coding of moving pictures and associated audio information: Systems*.
+- [J.83] ITU-T Recommendation J.83 (1997), *Digital multi-programme systems for television, sound and data services for cable distribution*.
+- [J.122] ITU-T Recommendation J.122 (2002), *Second-generation transmission systems for interactive cable television services – IP cable modems*.
+- [J.210] ITU-T Recommendation J.210 (2006), *Downstream RF interface for Cable Modem Termination Systems*.
+- [J.211] ITU-T Recommendation J.211 (2006), *Timing interface for Cable Modem Termination Systems*.
+- [IANA-PORTS] IANA (2004), *Port Numbers*.
+- [IEEE-802.1Q] IEEE Std 802.1Q-2005, *IEEE Standard for Local and Metropolitan Area Networks – Virtual Bridged Local Area Networks*.
+- [IEEE-802.3] IEEE Std 802.3-2005, *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 Specification*.
+- [RFC-IP] IETF RFC 791 (1981), *Internet Protocol – DARPA Internet Program – Protocol specification*.
+- [RFC-L2TP-DSCP] IETF RFC 3308 (2002), *Layer Two Tunnelling Protocol (L2TP) Differentiated Services Extension*.
+- [RFC-L2TPv3] IETF RFC 3931 (2005), *Layer Two Tunnelling Protocol – Version 3 (L2TPv3)*.
+- [RFC-MTU] IETF RFC 1191 (1990), *Path MTU Discovery*.
+- [RFC-PHBID-AF] IETF RFC 2597 (1999), *Assured Forwarding PHB Group*.
+- [RFC-PHBID-EF] IETF RFC 3246 (2002), *An Expedited Forwarding PHB (Per-Hop Behaviour)*.
+- [RFC-UDP] IETF RFC 768 (1980), *User Datagram Protocol*.
+
+## 2.2 Informative references
+
+- [DVB-RF] ETSI EN 300 429 V1.2.1 (1998), *Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for cable systems*.
+
+|              |                                                                                                                                                                                                                                         |
+|--------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| [ERMI]       | <i>Edge Resource Manager Interface</i> , CM-SP-ERMI-I02-051209,<br>9 December 2005, Cable Television Laboratories, Inc.                                                                                                                 |
+| [ISO 8802-2] | ISO/IEC 8802-2:1998 (IEEE Std 802.2:1994) – <i>Information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Specific requirements – Part 2: Logical link control</i> . |
+| [MOSSI]      | <i>DOCSIS M-CMTS Operations Support Interface</i> , CM-SP-M-OSSI-I02-051209, 9 December 2005, Cable Television Laboratories, Inc.                                                                                                       |
+| [RFC-DSCP-1] | IETF RFC 2983 (2000), <i>Differentiated Services and Tunnels</i> .                                                                                                                                                                      |
+| [RFC-DSCP-2] | IETF RFC 3260 (2002), <i>New Terminology and Clarifications for Diffserv</i> .                                                                                                                                                          |
+| [VCCV]       | IETF draft-ietf-pwe3-vccv-12.txt, <i>Pseudo Wire Virtual Circuit Connectivity Verification (VCCV)</i> , January 2007.                                                                                                                   |
+
+## 2.3 Reference acquisition
+
+- Cable Television Laboratories, Inc., Internet: <http://www.cablelabs.com/>; <http://www.cablemodem.com/specifications/>
+- The Institute of Electrical and Electronics Engineers, Inc, Internet: <http://standards.ieee.org>
+- Internet Engineering Task Force (IETF), Internet: <http://www.ietf.org>
+- Internet Assigned Numbers Authority, IANA, Internet: <http://www.iana.org>
+- European Telecommunications Standards Institute, ETSI, <http://www.etsi.org>
+
+# 3 Terms and definitions
+
+This Recommendation defines the following terms:
+
+- 3.1 bonded channels:** A logical channel comprising multiple individual channels.
+- 3.2 cable modem (CM):** A modulator-demodulator at subscriber locations intended for use in conveying data communications on a cable television system.
+- 3.3 converged interconnect network:** The network (generally gigabit Ethernet) that connects an M-CMTS Core to an EQAM.
+- 3.4 customer premises equipment (CPE):** Equipment at the end user's premises; may be provided by the service provider.
+- 3.5 data rate:** Throughput, data transmitted in units of time usually in bits per second (bit/s).
+- 3.6 decibels (dB):** Ratio of two power levels expressed mathematically as  $\text{dB} = 10\log_{10}(P_{\text{OUT}}/P_{\text{IN}})$ .
+- 3.7 decibel-millivolt (dBmV):** Unit of RF power expressed in decibels relative to 1 millivolt, where  $\text{dBmV} = 20\log_{10}(\text{value in mV}/1\text{ mV})$ .
+- 3.8 downstream (DS):**
+- 1) Transmissions from CMTS to CM. This includes transmission from the M-CMTS Core to the EQAM as well as the RF transmissions from the EQAM to the CM.
+  - 2) RF spectrum used to transmit signals from a cable operator's headend or hub site to subscriber locations.
+- 3.9 edge QAM modulator (EQAM):** A headend or hub device that receives packets of digital video or data. It re-packetizes the video or data into an MPEG transport stream and digitally modulates the digital transport stream onto a downstream RF carrier using quadrature amplitude modulation (QAM).
+
+- 3.10 flow:** A stream of packets in DEPI used to transport data of a certain priority from the M-CMTS Core to a particular QAM channel of the EQAM. In PSP operation, there can exist several flows per QAM channel.
+- 3.11 GigE (GE):** Gigabit Ethernet (1 Gbit/s).
+- 3.12 hybrid fibre/coax (HFC) system:** A broadband bidirectional shared-media transmission system using optical fibre trunks between the headend and the fibre nodes, and coaxial cable distribution from the fibre nodes to the customer locations.
+- 3.13 Institute of Electrical and Electronics Engineers (IEEE):** A voluntary organization which, among other things, sponsors standards committees and is accredited by the American National Standards Institute (ANSI).
+- 3.14 Internet Engineering Task Force (IETF):** A body responsible for, among other things, developing standards used in the Internet.
+- 3.15 Internet Protocol (IP):** An Internet network-layer protocol.
+- 3.16 L2TP access concentrator (LAC):** If an L2TP Control Connection Endpoint (LCCE) is being used to cross-connect an L2TP session directly to a data link, we refer to it as an L2TP Access Concentrator (LAC). An LCCE may act as both an L2TP Network Server (LNS) for some sessions and LAC for others, so these terms must only be used within the context of a given set of sessions unless the LCCE is in fact single purpose for a given topology.
+- 3.17 L2TP attribute value pair (AVP):** The L2TP variable-length concatenation of a unique Attribute (represented by an integer), a length field, and a Value containing the actual value identified by the attribute.
+- 3.18 L2TP control connection:** An L2TP control connection is a reliable control channel that is used to establish, maintain, and release individual L2TP sessions as well as the control connection itself.
+- 3.19 L2TP control connection endpoint (LCCE):** An L2TP node that exists at either end of an L2TP control connection. May also be referred to as LAC or LNS, depending on whether tunnelled frames are processed at the data link (LAC) or network layer (LNS).
+- 3.20 L2TP control connection ID:** The Control Connection ID field contains the identifier for the control connection, a 32-bit value. The Assigned Control Connection ID AVP, Attribute Type 61, contains the ID being assigned to this control connection by the sender. The Control Connection ID specified in the AVP must be included in the Control Connection ID field of all control packets sent to the peer for the lifetime of the control connection. Because a Control Connection ID value of 0 is used in this special manner, the zero value must not be sent as an Assigned Control Connection ID value.
+- 3.21 L2TP control message:** An L2TP message used by the control connection.
+- 3.22 L2TP data message:** An L2TP message used by the data channel.
+- 3.23 L2TP endpoint:** A node that acts as one side of an L2TP tunnel.
+- 3.24 L2TP network server (LNS):** If a given L2TP session is terminated at the L2TP node and the encapsulated network layer (L3) packet processed on a virtual interface, we refer to this L2TP node as an L2TP Network Server (LNS). A given LCCE may act as both an LNS for some sessions and LAC for others, so these terms must only be used within the context of a given set of sessions unless the LCCE is in fact single purpose for a given topology.
+- 3.25 L2TP pseudowire (PW):** An emulated circuit as it traverses a packet-switched network. There is one Pseudowire per L2TP Session.
+
+- 3.26 L2TP pseudowire type:** The payload type being carried within an L2TP session. Examples include PPP, Ethernet, and Frame Relay.
+- 3.27 L2TP session:** An L2TP session is the entity that is created between two LCEs in order to exchange parameters for and maintain an emulated L2 connection. Multiple sessions may be associated with a single Control Connection.
+- 3.28 L2TP session ID:** A 32-bit field containing a non-zero identifier for a session. L2TP sessions are named by identifiers that have local significance only. That is, the same logical session will be given different Session IDs by each end of the control connection for the life of the session. When the L2TP control connection is used for session establishment, session IDs are selected and exchanged as Local Session ID AVPs during the creation of a session. The Session ID alone provides the necessary context for all further packet processing, including the presence, size, and value of the Cookie, the type of L2-Specific Sublayer, and the type of payload being tunnelled.
+- 3.29 MAC domain:** A grouping of layer 2 devices that can communicate with each other without using bridging or routing. In DOCSIS, it is the group of CMs that are using upstream and downstream channels linked together through a MAC forwarding entity.
+- 3.30 maximum transmission unit (MTU):** The layer 3 payload of a layer 2 frame.
+- 3.31 media access control (MAC):** Used to refer to the layer 2 element of the system which would include DOCSIS framing and signalling.
+- 3.32 modulation error ratio (MER):** The ratio of the average symbol power to average error power.
+- 3.33 physical media dependent (PMD) sublayer:** A sublayer of the Physical layer which is concerned with transmitting bits or groups of bits over particular types of transmission link between open systems and which entails electrical, mechanical and handshaking procedures.
+- 3.34 QAM channel (QAM ch):** Analog RF channel that uses quadrature amplitude modulation (QAM) to convey information.
+- 3.35 quadrature amplitude modulation (QAM):** A modulation technique in which an analog signal's amplitude and phase vary to convey information, such as digital data.
+- 3.36 radio frequency (RF):** In cable television systems, this refers to electromagnetic signals in the range 5 to 1000 MHz.
+- 3.37 radio frequency interface (RFI):** Term encompassing the downstream and the upstream radio frequency interfaces.
+- 3.38 request for comments (RFC):** A technical policy document of the IETF; these documents can be accessed on the World Wide Web at <http://www.rfc-editor.org/>.
+- 3.39 session:** An L2TP data plane connection from the M-CMTS Core to the QAM channel. There must be one session per QAM Channel. There is one DEPI pseudowire type per session. There may be one MPT flow or one or more PSP flows per session. Multiple sessions may be bound to a single control connection.
+- 3.40 StopCCN:** L2TPv3 Stop-Control-Connection-Notification message.
+- 3.41 upconverter:** A device used to change the frequency range of an analog signal, usually converting from a local oscillator frequency to an RF transmission frequency.
+- 3.42 upstream (US):**
+- 1) Transmissions from CM to CMTS. This includes transmission from the EQAM to M-CMTS Core as well as the RF transmissions from the CM to the EQAM.
+  - 2) RF spectrum used to transmit signals from a subscriber location to a cable operator's headend or hub site.
+
+**3.43 upstream channel descriptor (UCD):** The MAC Management Message used to communicate the characteristics of the upstream physical layer to the cable modems.
+
+**3.44 video-on-demand (VoD) system:** System that enables individuals to select and watch video content over a network through an interactive television system.
+
+# **4 Abbreviations, acronyms and conventions**
+
+## **4.1 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations:
+
+|                       |                                                  |
+|-----------------------|--------------------------------------------------|
+| ACK                   | L2TPv3 Explicit Acknowledgement message          |
+| AVP                   | L2TPv3 Attribute Value Pair                      |
+| CDN                   | L2TPv3 Call-Disconnect-Notify message            |
+| CIN                   | Converged Interconnect Network                   |
+| CLI                   | Command Line Interface                           |
+| CM                    | Cable Modem                                      |
+| CMCI                  | Cable Modem CPE Interface                        |
+| CMTS                  | Cable Modem Termination System                   |
+| CPE                   | Customer Premises Equipment                      |
+| CRC                   | Cyclic Redundancy Check                          |
+| CRC-16                | CRC of length 16                                 |
+| CSMA                  | Carrier Sense Multiple Access                    |
+| DEPI                  | Downstream External PHY Interface                |
+| DOCSIS                | Data-Over-Cable Service Interface Specifications |
+| DOCSIS-MPT<br>(D-MPT) | DOCSIS MPT Mode                                  |
+| DRFI                  | Downstream Radio Frequency Interface             |
+| DS                    | Downstream                                       |
+| DSCP                  | Differentiated Services Code Point               |
+| DTI                   | DOCSIS Timing Interface                          |
+| DTS                   | DOCSIS Time Stamp, 32 bits                       |
+| EQAM                  | Edge QAM                                         |
+| ERM                   | Edge Resource Manager                            |
+| ERMI                  | Edge Resource Manager Interface                  |
+| ETSI                  | European Telecommunications Standards Institute  |
+| FQDN                  | Fully Qualified Domain Name                      |
+| GE                    | Gigabit Ethernet (GigE)                          |
+| HELLO                 | L2TPv3 Hello message                             |
+| HFC                   | Hybrid Fibre/Coax                                |
+| ICCN                  | L2TPv3 Incoming-Call-Connected message           |
+
+|         |                                                                                                                                                                                                         |
+|---------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| ICRP    | L2TPv3 Incoming-Call-Reply message                                                                                                                                                                      |
+| ICRQ    | L2TPv3 Incoming-Call-Request message                                                                                                                                                                    |
+| IEEE    | Institute of Electrical and Electronics Engineers                                                                                                                                                       |
+| IETF    | Internet Engineering Task Force                                                                                                                                                                         |
+| IP      | Internet Protocol                                                                                                                                                                                       |
+| IPv4    | Internet Protocol version 4                                                                                                                                                                             |
+| ISO     | International Organization for Standardization                                                                                                                                                          |
+| ITU     | International Telecommunication Union                                                                                                                                                                   |
+| ITU-T   | International Telecommunication Union – Telecommunication Standardization Sector                                                                                                                        |
+| L2TP    | Layer 2 Transport Protocol                                                                                                                                                                              |
+| L2TPv3  | Layer 2 Transport Protocol – Version 3                                                                                                                                                                  |
+| L3      | Layer 3                                                                                                                                                                                                 |
+| LAC     | L2TP Access Concentrator                                                                                                                                                                                |
+| LCCE    | L2TP Control Connection Endpoint                                                                                                                                                                        |
+| LNS     | L2TP Network Server                                                                                                                                                                                     |
+| LSB     | Least Significant Bit                                                                                                                                                                                   |
+| M/N     | Relationship of integer numbers M,N that represents the ratio of the downstream symbol clock rate to the DOCSIS master clock rate                                                                       |
+| MAC     | Media Access Control                                                                                                                                                                                    |
+| M-CMTS  | Modular Cable Modem Termination System                                                                                                                                                                  |
+| MER     | Modulation Error Ratio                                                                                                                                                                                  |
+| MIB     | Management Information Base                                                                                                                                                                             |
+| MPEG    | Moving Picture Experts Group                                                                                                                                                                            |
+| MPEG-TS | Moving Picture Experts Group Transport Stream                                                                                                                                                           |
+| MPT     | MPEG-TS mode of DEPI                                                                                                                                                                                    |
+| MPTS    | Multi-Program Transport Stream                                                                                                                                                                          |
+| MSB     | Most Significant Bit                                                                                                                                                                                    |
+| MTU     | Maximum Transmission Unit                                                                                                                                                                               |
+| OSSI    | Operations Support System Interface                                                                                                                                                                     |
+| PCR     | Program Clock Reference. A time stamp in the Video Transport Stream from which decoder timing is derived.                                                                                               |
+| PHY     | Physical Layer                                                                                                                                                                                          |
+| PID     | Packet Identifier; PID (system): A unique integer value used to identify elementary streams of a program in a single or multi-program Transport Stream as described in 2.4.3 of [H.222.0   ISO 13818-1] |
+| PMD     | Physical Media Dependent Sublayer                                                                                                                                                                       |
+| PPP     | Point-to-Point Protocol                                                                                                                                                                                 |
+
+|         |                                                     |
+|---------|-----------------------------------------------------|
+| PSI     | Program Specific Information                        |
+| PSP     | Packet Streaming Protocol                           |
+| PW      | Pseudowire                                          |
+| QAM     | Quadrature Amplitude Modulation                     |
+| RF      | Radio Frequency                                     |
+| RFC     | Request For Comments                                |
+| RFI     | Radio Frequency Interface                           |
+| SCCCN   | L2TPv3 Start-Control-Connection-Connected message   |
+| SCCRP   | L2TPv3 Start-Control-Connection-Reply message       |
+| SCCRQ   | L2TPv3 Start-Control-Connection-Request message     |
+| S-CDMA  | Synchronous Code Division Multiple Access           |
+| SLI     | L2TPv3 Set Link Info message                        |
+| SPTS    | Single Program Transport Stream                     |
+| StopCCN | L2TPv3 Stop-Control-Connection-Notification message |
+| TSID    | MPEG2 Transport Stream ID                           |
+| UCD     | Upstream Channel Descriptor                         |
+| UDP     | User Datagram Protocol                              |
+| US      | Upstream                                            |
+| VoD     | Video-on-Demand                                     |
+
+## 4.2 Conventions
+
+In this Recommendation, the following convention applies any time a bit field is displayed in a figure. The bit field should be interpreted by reading the figure from left to right, then from top to bottom, with the MSB being the first bit so read and the LSB being the last bit so read.
+
+Throughout this Recommendation, the words that are used to define the significance of particular requirements are capitalized. These words are:
+
+**"MUST"** This word or the adjective **"REQUIRED"** means that the item is an absolute requirement of this Recommendation.
+
+**"MUST NOT"** This phrase means that the item is an absolute prohibition of this Recommendation.
+
+**"SHOULD"** This word or the adjective **"RECOMMENDED"** means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighed before choosing a different course.
+
+**"SHOULD NOT"** This phrase means that there may exist valid reasons in particular circumstances when the listed behaviour is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behaviour described with this label.
+
+**"MAY"** This word or the adjective **"OPTIONAL"** means that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product; for example, another vendor may omit the same item.
+
+# 5 Technical overview
+
+This clause is informative.
+
+## 5.1 System architecture
+
+![Figure 5-1/J.212 – Modular CMTS reference architecture diagram](7efae06af3af43ffe5d4b956a679cf54_img.jpg)
+
+The diagram illustrates the modular CMTS reference architecture. At the center is the **M-CMTS** (Modular Cable Modem Termination System) block, which contains the **M-CMTS core**, **Upstream receiver**, and **EQAM** (Edge QAM) components. The **M-CMTS core** is connected to the **Wide area network** via the **Network Side Interface (NSI)**. It also connects to the **DOCSIS timing server** via the **DOCSIS Timing Interface (DTI)**. The **EQAM** is connected to the **M-CMTS core** via the **Downstream External-PHY Interface (DEPI)**. The **EQAM** is connected to the **HE Combining / Hybrid Fiber-coax Network (HFC)** via the **Downstream RF Interface (DRFI)**. The **HFC** is connected to the **Cable Modem (CM)** via the **Radio Frequency Interface (RFI)**. The **CM** is connected to the **Customer Premises Equipment (CPE)** via the **Cable Modem to CPE Interface (CMCI)**. The **Operations support system** is connected to the **M-CMTS core** via the **Operations Support System Interface (OSSI)**. The **Edge resource manager** is connected to the **M-CMTS core** via the **Edge Resource Manager Interfaces (ERMI)**. A legend at the bottom left indicates that a double-headed arrow represents the **M-CMTS interface** and a single-headed arrow represents the **Other DOCSIS interface**. The reference number **J.212(06)\_F5-1** is shown in the bottom right corner.
+
+Figure 5-1/J.212 – Modular CMTS reference architecture diagram
+
+**Figure 5-1/J.212 – Modular CMTS reference architecture**
+
+In the M-CMTS architecture, a device referred to as the M-CMTS Core contains the DOCSIS MAC. This includes all signalling functions, downstream bandwidth scheduling, and DOCSIS framing. The EQAM box contains mainly PHY related circuitry, such as QAM modulators, and tunnelling logic, to connect to the M-CMTS Core.
+
+### 5.1.1 Reference architecture
+
+The reference architecture for a Modular CMTS system is shown in Figure 5-1. This architecture contains several pieces of equipment along with interfaces between those pieces of equipment. This clause will briefly introduce each device and interface.
+
+**The Edge QAM device**, or EQAM for short, has its origins in the VoD environment. This device typically has one or more gigabit Ethernet interfaces and multiple QAM modulators and RF upconverters. This EQAM is being adapted for use in a Modular CMTS environment. Each individual output of these devices is often referred to as QAM Channel rather than the combination "QAM Modulator and RF Upconverter".
+
+**The M-CMTS Core** contains everything a traditional CMTS does, except for functions performed in the EQAM. The M-CMTS Core contains the downstream MAC and all the initialization and operational DOCSIS related software.
+
+This diagram shows the Upstream Receivers of DOCSIS upstream channels located internally to the M-CMTS Core. However, there is nothing preventing an implementation of a Modular CMTS from using a proprietary external upstream receiver interface. In the future, an interface may be defined between the M-CMTS Core and external upstream receivers.
+
+**The DOCSIS Timing Interface (DTI) Server** provides a common master clock frequency and a DOCSIS timestamp to other M-CMTS elements.
+
+**DEPI**, the Downstream External PHY Interface, is the interface between the M-CMTS Core and the EQAM. More specifically, it is an IP Tunnel between the MAC and PHY in a Modular CMTS
+
+system which contains both a data path for DOCSIS frames, and a control path for setting up, maintaining, and tearing down sessions.
+
+**DRFI**, or Downstream Radio Frequency Interface, is intended to capture all the current and future RF requirements for the downstream direction for both integrated DOCSIS CMTS systems, Modular DOCSIS CMTS systems, and VoD EQAM systems.
+
+**DTI**, or DOCSIS Timing Interface, is a point-to-point interface from the DTI Server to other M-CMTS elements. The DTI Recommendation [J.211] defines DTI Server and DTI Client behaviours and protocols. The DTI Server is the Timing Signal Generator while each M-CMTS Core and EQAM has a DTI Client. The DTI Server distributes a DOCSIS master clock and a DOCSIS timestamp over unshielded twisted pair (UTP). The DTI protocol automatically compensates for cable length and ensures that all M-CMTS elements have the same sense of time and frequency.
+
+**ERMI**, or Edge Resource Manager Interface [ERMI], involves three interfaces: a registration interface between an EQAM and ERM (Edge Resource Manager), a control interface between an EQAM and an ERM, and a control interface between an M-CMTS Core and an ERM. The first interface is used to register and unregister EQAM resources (i.e., QAM channels) with an ERM. The second interface is used by an ERM to request QAM channel resources from an EQAM, and by an EQAM to deliver resources to an ERM. The third interface is used by the M-CMTS Core to request specific QAM channel resources from the ERM, and by the ERM to respond to such requests with the location of QAM channel resources.
+
+**MOSSI**, or Modular CMTS Operations Support System Interface [MOSSI], provides the management interface to each system component. This interface is an extension of the OSSI defined in the DOCSIS Recommendations for monitoring a management of CMTS functions. This interface could be used, in place of an ERM and the ERMI, to statically configure and associate QAM channel resources with M-CMTS Cores. This interface allows for the modification of a QAM channel's physical layer parameter by either the M-CMTS Core or the EQAM, and provides a mechanism by which the operator can "lock" certain parameters at the EQAM so that they can only be modified there. This Recommendation defines the mechanism to communicate these parameter settings to the other side.
+
+**NSI**, or the Network Side Interface, is unchanged, and is the physical interface the CMTS uses to connect to the backbone network. Today, this is typically 100 Mbit/s or 1 Gbit/s Ethernet.
+
+**CMCI**, or Cable Modem to Customer Premises Equipment Interface, is also unchanged, and is typically 10/100 Mbit/s Ethernet or USB.
+
+### 5.1.2 DEPI operation
+
+DEPI is an IP Tunnel that exists between the DOCSIS MAC in the M-CMTS Core and the DOCSIS PHY that exists in the EQAM. DEPI's job is to take either formatted DOCSIS frames or MPEG packets and transport them through a layer 2 or layer 3 network and deliver them to the EQAM for transmission.
+
+The base protocol that is used for the DEPI is the Layer 2 Tunnelling Protocol Version 3, or L2TPv3 for short [RFC-L2TPv3]. L2TPv3 is an IETF protocol that is a generic protocol for creating a pseudowire. A pseudowire is a mechanism to transparently transport a layer 2 protocol over a layer 3 network. Examples of protocols supported by L2TPv3 include ATM, HDLC, Ethernet, Frame Relay, PPP, etc.
+
+Clause 8.1 "L2TPv3 Transport Packet Format" shows the format of an L2TPv3 data packet. Each data packet contains a 32-bit session ID which is associated with a single QAM Channel on the EQAM. The UDP header is optional in the L2TPv3 protocol. In the DEPI protocol, both the EQAM and the M-CMTS core are required to support the ability to include the UDP header in both the control plane and the forwarding plane (see 7.3). Support for DEPI operation without the
+
+UDP header is optional for both the EQAM and M-CMTS core, and can be used if both ends support it, as described in clauses 7.3 and 8.
+
+L2TPv3 then permits a sub-header to exist whose definition is specific to the payload being carried. The control channel allows for signalling messages to be sent between the M-CMTS Core and EQAM. Typical control messages will set up a "control connection" between the M-CMTS Core and EQAM, and then set up multiple data sessions (one for each downstream QAM channel). Each session can utilize different DiffServ Code Points (DSCPs), and support different encapsulation protocols.
+
+There are two basic tunnelling techniques defined by DEPI. The first technique, known as D-MPT mode, transports multiple 188-byte MPEG-TS packets by placing them into the L2TPv3 payload with a unique sub-header which contains a sequence number so packet drops can be detected. The encapsulation of DOCSIS Frames into MPEG-TS packets is performed in the M-CMTS Core. The second technique, known as the Packet Streaming Protocol (PSP), transports DOCSIS Frames in the L2TPv3 payload. The DOCSIS Frames are then encapsulated in MPEG-TS packets within the EQAM. PSP mode allows DOCSIS frames to be both concatenated, to increase network performance, and fragmented, in case the tunnelled packets exceed the network MTU size.
+
+One of the technical considerations of the Modular CMTS architecture is its impact on the round trip request-grant delay time. The request-grant delay time is the time from when a CM requests bandwidth using an uncontended bandwidth request (REQ) to when it receives a MAP message with the granted transmit opportunity in it.
+
+To prevent the MAP from being slowed down by other traffic in the CIN, the DOCSIS traffic (or a subset containing the MAP messages) may be sent in an independent L2TPv3 flow that has a unique DSCP. This DSCP will have a "per hop behaviour (PHB)" that will give MAPs the highest priority and lowest latency service.
+
+### 5.1.3 EQAM Operation
+
+![EQAM block diagram showing four input interfaces on the left and one output interface on the right.](21ad58fee90f2be50708ff541d225507_img.jpg)
+
+The diagram shows a central rectangular block labeled "EQAM". To its left, four horizontal lines with arrowheads pointing into the block represent input interfaces, labeled from top to bottom: "Video over MPEG-TS", "DEPI: DOCSIS MPT", "DEPI: DOCSIS PSP", and "DTI". To the right of the block, a single horizontal line with an arrowhead pointing away from the block represents the output interface, labeled "DRFI". In the bottom right corner of the diagram, there is a small text label "J.212(06)\_F5-2".
+
+EQAM block diagram showing four input interfaces on the left and one output interface on the right.
+
+**Figure 5-2/J.212 – EQAM block diagram**
+
+Figure 5-2 shows a high level block diagram of an EQAM that is capable of handling either Video MPEG traffic or DOCSIS traffic. The expression "D-MPT" is an acronym for DOCSIS MPEG Transport.
+
+The first interface that is shown is the VoD transport. VoD SPTS or MPTS streams are received with a format of MPEG packets over UDP/IP. The video processing functions generally include de-jittering, re-multiplexing PID remapping, MPEG-2 PSI insertion, and PCR timestamp correction. These functions are not defined in this Recommendation.
+
+The next set of interfaces are the DEPI interfaces.
+
+The first interface defined is D-MPT. This is a mode where the EQAM must search the incoming D-MPT frames for DOCSIS SYNC messages and correct the timestamp value in these messages based upon the EQAM's internal DOCSIS timestamp which has been derived from DTI. The resulting D-MPT frames are then copied to the QAM channel without further interpretation or modification. This mode is intended for DOCSIS frames where the MAP is embedded into the stream and network latency or jitter is not a concern.
+
+Because D-MPT mode encapsulates all DOCSIS traffic into a single DEPI flow, it does not allow for QoS differentiation among various types of traffic either across the CIN or within the EQAM. For example, acceleration of MAPs relative to other DOCSIS data is not possible when D-MPT mode is used. This may still give acceptable performance when the delay and jitter introduced onto DEPI packets by the CIN and EQAM are determined by the operator to be sufficiently low.
+
+Certain network conditions and/or architectures may reduce network delay and/or jitter and make it more likely that DOCSIS MPT mode will give acceptable system performance. Some examples are:
+
+- networks with a very small number of hops (e.g., 1 or 2 hops), especially if these hops are all switches (which generally introduce less delay and jitter than routers);
+- networks which are largely shared with video traffic from VoD servers to EQAMs, on which most of the traffic is video and it is acceptable to prioritize all DEPI traffic on the network above all VoD traffic;
+- networks which are lightly loaded so that delays due to congestion are highly unlikely.
+
+Such conditions may exist on today's CINs. They may be less likely to occur as deployments become denser and total IP traffic increases. Evaluation of network conditions and decisions about acceptable performance levels with DOCSIS MPT mode are in the realm of operator discretion.
+
+The next interface is DOCSIS PSP. This interface transports DOCSIS Data and MAPs in separate flows which are streamed together in a uniform byte stream by the M-CMTS Core. The PSP re-assembly engine removes this overhead and recovers the DOCSIS Frames. The PSP scheduler then allows MAPs to be placed in order, ahead of data and SYNC messages. In PSP mode, the EQAM generates all SYNC messages as detailed in 6.1.1. The output is then delivered to a transmission convergence layer which converts the results to a DOCSIS MPEG stream.
+
+The last interface is the DTI interface which provides a common frequency and DOCSIS timestamp. The reference is used to synchronize the downstream symbol rate and DOCSIS timestamp for use with DOCSIS cable modems. The timestamp is used for the DOCSIS SYNC correction.
+
+The output from the EQAM consists of a stream of MPEG frames which carry video and/or DOCSIS data, and are modulated onto an RF carrier in accordance with the DRFI Recommendation [J.210].
+
+## 5.2 Bonding services model
+
+![Figure 5-3/J.212 – Bonding services model diagram](7f25db95ce3916c0e09803b861a2f7bc_img.jpg)
+
+The diagram illustrates the bonding services model. On the left, an 'M-CMTS core' contains two 'Bonding group' boxes. Arrows from each bonding group point to two separate 'EQAM' boxes. Each 'EQAM' box contains two 'QAM channel' boxes. All four 'QAM channel' boxes have arrows pointing to a single circular node labeled 'HFC plant'. The label 'J.212(06)\_F5-3' is located at the bottom right of the diagram.
+
+Figure 5-3/J.212 – Bonding services model diagram
+
+Figure 5-3/J.212 – Bonding services model
+
+Downstream Channel Bonding refers to the forwarding of a stream of DOCSIS frames across multiple QAM carriers.
+
+In the Modular CMTS architecture, the Downstream Channel Bonding is implemented in the M-CMTS Core. At the M-CMTS Core, packets from the IP backbone are placed in a DOCSIS frame. That DOCSIS frame is then sent to one of several QAM channels in a Bonding Group. The frame may be transported using D-MPT or PSP.
+
+In this system, the EQAM is unaware that it is doing bonding. It is also unaware of any of the details of the Bonding protocol.
+
+## 5.3 Multiple services model
+
+![Figure 5-4/J.212 – Multi-service mode diagram](12de9b926df0384ec07702671827c9cd_img.jpg)
+
+The diagram illustrates the multi-service mode. On the left, four input streams are shown: 'Video over MPEG-TS', 'Video over IP', 'Data over IP', and 'Voice over IP'. Arrows from 'Video over IP', 'Data over IP', and 'Voice over IP' point to an 'M-CMTS core (with DOCSIS MAC)' box. An arrow from 'Video over MPEG-TS' points to an 'Edge QAM (with DOCSIS PHY)' box. An arrow labeled 'DEPI' and 'Non-bonded and bonded DOCSIS traffic' points from the 'M-CMTS core' box to the 'Edge QAM' box. An arrow labeled 'DRFI' points from the 'Edge QAM' box to the right. The label 'J.212(06)\_F5-4' is located at the bottom right of the diagram.
+
+Figure 5-4/J.212 – Multi-service mode diagram
+
+Figure 5-4/J.212 – Multi-service mode
+
+The Modular CMTS (M-CMTS) architecture reflects an effort to merge the video-on-demand (VoD) and high speed data (HSD) applications. This effort is made in anticipation of achieving higher efficiencies than are possible with two separate transmission networks feeding into the cable plant. In particular, the M-CMTS effort has repartitioned the traditional CMTS architecture so that the transmission technology which is common to both the VoD environment and the HSD environment will be able to share the same EQAM devices.
+
+In a video delivery system, the EQAM is used to deliver video streams in MPEG-TS format to set top boxes at the subscribers' premises. This functionality will continue to be used in the future and operates independently of other processing which is described here. The M-CMTS architecture adds new interfaces which are unique to HSD service. These interfaces support both traditional DOCSIS and multichannel (bonded) DOCSIS payloads as received from the M-CMTS Core device.
+
+The M-CMTS Core provides the gateway functionality between the IP-based core network and the CIN. As such, the M-CMTS Core provides support for a multitude of services – including, but not limited to video over IP, voice-over-IP (VoIP), email, gaming, video telephony, etc.
+
+# 6 DEPI architecture
+
+This clause is normative.
+
+## 6.1 DEPI Data Path
+
+![Figure 6-1/J.212 – Downstream EQAM block diagram. The diagram illustrates the internal data path of the EQAM. It shows two main input paths: DEPI: DOCSIS MPT and DEPI: DOCSIS PSP. The DEPI: DOCSIS MPT path goes through a QoS queue and then to a SYNC correction block. The DEPI: DOCSIS PSP path goes through multiple PSP termination blocks, which then feed into a central switching block (X). From the X block, the data is distributed to multiple QoS queues and a SYNC insertion block. All these queues and the SYNC insertion block feed into a Packet scheduler. The Packet scheduler output goes to an MPEG-TS TC block. The MPEG-TS TC block output goes to a QAM modulator and upconverter, which produces the DRFI output. A Video over MPEG-TS path goes through a Video processing block and then to the QAM modulator and upconverter. A DEPI: DLM-EE-RP Return path is shown at the top left. A DTI path goes to a DOCSIS timing block, which provides timing information to the Packet scheduler and the QAM modulator and upconverter. A DEPI: DLM-EI-RP Return path is shown at the bottom left. The diagram is labeled J.212(06)_F6-1 at the bottom right.](523ab7b925beb555f88b2e1e1336974f_img.jpg)
+
+Figure 6-1/J.212 – Downstream EQAM block diagram. The diagram illustrates the internal data path of the EQAM. It shows two main input paths: DEPI: DOCSIS MPT and DEPI: DOCSIS PSP. The DEPI: DOCSIS MPT path goes through a QoS queue and then to a SYNC correction block. The DEPI: DOCSIS PSP path goes through multiple PSP termination blocks, which then feed into a central switching block (X). From the X block, the data is distributed to multiple QoS queues and a SYNC insertion block. All these queues and the SYNC insertion block feed into a Packet scheduler. The Packet scheduler output goes to an MPEG-TS TC block. The MPEG-TS TC block output goes to a QAM modulator and upconverter, which produces the DRFI output. A Video over MPEG-TS path goes through a Video processing block and then to the QAM modulator and upconverter. A DEPI: DLM-EE-RP Return path is shown at the top left. A DTI path goes to a DOCSIS timing block, which provides timing information to the Packet scheduler and the QAM modulator and upconverter. A DEPI: DLM-EI-RP Return path is shown at the bottom left. The diagram is labeled J.212(06)\_F6-1 at the bottom right.
+
+**Figure 6-1/J.212 – Downstream EQAM block diagram**
+
+A simplified logical block diagram of the internal data path of the EQAM is shown in Figure 6-1.
+
+It is recognized, but not specified by this Recommendation, that the EQAM may receive non-DOCSIS MPEG elementary streams which have been encapsulated in MPEG packets and placed in a UDP datagram. This Recommendation does not define requirements for transport of this type of traditional MPEG video. However, it is recognized that M-CMTS EQAM implementations may (and likely will) be capable of transporting traditional MPEG video (either interleaved with DOCSIS traffic on a single QAM channel, or on separate QAM channels within the same EQAM chassis).
+
+The M-CMTS Core MUST support PSP mode, D-MPT mode, or both. The EQAM MUST support PSP mode, D-MPT mode, or both.
+
+Within a session, the M-CMTS Core MUST support either one priority level of D-MPT or at least two priority levels of PSP, where each priority level would have a different DSCP. The M-CMTS Core MUST provide a mechanism to map DOCSIS traffic to the multiple priority levels of PSP. The M-CMTS Core MUST NOT attempt to establish a session which includes both PSP and D-MPT flows.
+
+Within a session, the EQAM MUST support either one priority level of D-MPT or at least two priority levels of PSP, where each priority level would have a different DSCP. The EQAM is not intended to simultaneously support D-MPT and PSP within a single session, and MUST reject any attempt to establish such a session. Each priority level for each DEPI type, maps to one or more DEPI flows. The EQAM MUST support the establishment of a single DEPI flow per priority level. The EQAM MAY support the establishment of more than one DEPI flow per priority level. The mapping of individual flows to priority levels (QoS Queues) is vendor-specific (see Figure 7-3). The mapping of flows will be done through the local EQAM Command Line Interface (CLI) configuration.
+
+For both D-MPT and PSP modes, the EQAM MUST insert null MPEG packets when it has no data to send. The EQAM SHOULD NOT insert a null MPEG packet if it has data to send. Note that MPEG null insertion should take place prior to the correction of the DOCSIS SYNC message (refer to 6.1.1).
+
+### 6.1.1 DOCSIS D-MPT data path
+
+The DEPI DOCSIS D-MPT flows contain DOCSIS frames using the format as described in 8.2. All DOCSIS frames, including packet based frames and MAC management based frames, are included within the one D-MPT flow. The EQAM searches the D-MPT payload for any DOCSIS SYNC messages and performs SYNC corrections as described in 6.1.3.2. It then forwards the D-MPT packet to the RF interface.
+
+The intent of D-MPT mode is that MPEG packets can be received by the EQAM and forwarded directly to the RF interface without having to terminate and regenerate the MPEG framing. The only manipulation of the D-MPT payload is the SYNC correction.
+
+### 6.1.2 PSP data path
+
+The Packet Stream Protocol (PSP) is a layer-3 convergence layer protocol, which allows packets to be consecutively streamed together and fragmented at arbitrary boundaries. The intent of the PSP mode is to facilitate Quality of Service. This mode is to be used for transporting traditional DOCSIS data and signalling messages which use one or more DSCP values. For example, in order to reduce Request-Grant latency, MAP MAC management messages may be sent using a different DSCP on a different PSP flow than the rest of the DOCSIS channel. Refer to 6.2.1 for more information. The EQAM MUST support a minimum of two PSP receivers per QAM modulator. The intent of two receivers is to permit the implementation of a higher latency PSP flow and a lower latency PSP flow.
+
+Each PSP flow is terminated, and the DOCSIS Frames within the flow are extracted. The DOCSIS frames are placed into corresponding output QoS queues. The output of the QoS queues go to a Packet Scheduler, which decides which queue is to be serviced based upon the PHB (negotiated between the M-CMTS Core and EQAM) of the PSP flow, which carried the DOCSIS frames. The Packet Scheduler is also responsible for inserting DOCSIS SYNC messages within the time interval specified by the DOCSIS SYNC Control AVP (see Figure 7-31). The Packet Scheduler SHOULD support a strict priority scheduler. The Packet Scheduler MAY support other queue scheduling disciplines.
+
+The phrase "packet scheduler" is a general term that describes a method of applying priorities to different queues as packets are moved from different input queues to the output queue. An example of a typical Packet Scheduling algorithm would be Weighted Fair Queuing (WFQ) where some streams are given priority over other streams, but only up to some limit. This should not be confused with the more complex DOCSIS upstream scheduler, which deals with requests and grants.
+
+The output of the Packet Scheduler goes to a Transmission Convergence engine which places the DOCSIS frames into MPEG packets according to the requirements in [J.210]. This includes the
+
+insertion of stuffing bytes and the DOCSIS SYNC message as described by 6.1.3. The output of Transmission Convergence (TC) engine is sent to the RF Interface.
+
+PSP mode primarily provides acceleration of MAPs through the network, in an attempt to reduce Request Grant latency. The PSP mode is most useful when all or most traffic has migrated to DOCSIS, and therefore, marking MAPs with higher QoS, when compared to other DOCSIS traffic that is needed in order to provide lower latency for MAPs, when traversing a fully subscribed network. Therefore, PSP has value in the long term and is included to address the case where most or all traffic is carried to the home via DOCSIS.
+
+### 6.1.3 DOCSIS SYNC message
+
+#### 6.1.3.1 SYNC message format
+
+The DOCSIS Time Synchronization (SYNC) MAC message is transmitted by a Modular CMTS system at a periodic interval to establish MAC sublayer timing in cable modems. This message MUST use an FC field with FC\_TYPE = MAC Specific Header and FC\_PARM = Timing MAC Header. This MUST be followed by a Packet PDU in the format shown in Figure 6-2.
+
+![Diagram of DOCSIS SYNC MAC message format showing fields: FC, MAC PARM, LENGTH, HCS, DA, SA, Message Length, DSAP, SSAP, Control, DOCSIS Version, DOCSIS Type, Reserved, Timestamp, and CRC. It is divided into DOCSIS Header (6 bytes), DOCSIS MAC Management Message Header (20 bytes), Payload (4 bytes), and CRC (4 bytes).](7d3d5fb5d09c0cd35a9d637be241651e_img.jpg)
+
+|                |  |                |  |             |    |          |      |    |  |                                                 |
+|----------------|--|----------------|--|-------------|----|----------|------|----|--|-------------------------------------------------|
+| 0              |  | 7              |  | 15          |    | 23       |      | 31 |  |                                                 |
+| FC             |  | MAC PARM       |  | LENGTH      |    |          |      |    |  | DOCSIS Header (6 bytes)                         |
+| HCS            |  |                |  |             |    |          |      |    |  |                                                 |
+| DA             |  |                |  |             |    |          |      |    |  | DOCSIS MAC Management Message Header (20 bytes) |
+| DA             |  |                |  |             | SA |          |      |    |  |                                                 |
+| SA             |  |                |  |             |    |          |      |    |  |                                                 |
+| Message Length |  |                |  | DSAP        |    |          | SSAP |    |  |                                                 |
+| Control        |  | DOCSIS Version |  | DOCSIS Type |    | Reserved |      |    |  |                                                 |
+| Timestamp      |  |                |  |             |    |          |      |    |  | Payload (4 bytes)                               |
+| CRC            |  |                |  |             |    |          |      |    |  | CRC (4 bytes)                                   |
+
+J.212(06)\_F6-2
+
+Diagram of DOCSIS SYNC MAC message format showing fields: FC, MAC PARM, LENGTH, HCS, DA, SA, Message Length, DSAP, SSAP, Control, DOCSIS Version, DOCSIS Type, Reserved, Timestamp, and CRC. It is divided into DOCSIS Header (6 bytes), DOCSIS MAC Management Message Header (20 bytes), Payload (4 bytes), and CRC (4 bytes).
+
+Figure 6-2/J.212 – Format of a DOCSIS SYNC MAC message
+
+The fields MUST be as defined below:
+
+**FC, MAC PARM, LEN, HCS:** Common MAC frame header with FC\_PARM field to indicate a timing header – refer to J.122 for details.
+
+**Destination Address (DA):** Set to the DOCSIS MAC multicast address of 01-E0-2F-00-00-01.
+
+**Source Address (SA):** The MAC address of the M-CMTS Core. In PSP Mode, the EQAM learns the appropriate M-CMTS Core MAC address via explicit signalling during L2TPv3 session setup.
+
+**Msg Length:** Length of the MAC message from DSAP to the end of the payload.
+
+**DSAP:** The LLC null destination SAP (00) as defined by [ISO 8802-2].
+
+**SSAP:** The LLC null source SAP (00) as defined by [ISO 8802-2].
+
+**Control:** Unnumbered information frame (03) as defined by [ISO 8802-2].
+
+**DOCSIS Version:** Set to 1.
+
+**DOCSIS Type:** Set to 1 to indicate a SYNC message.
+
+**CMTS Timestamp:** The count state of an incrementing 32-bit binary counter clocked with the master clock derived from [J.211].
+
+The CMTS timestamp represents the count state at the instant that the first byte (or a fixed time offset from the first byte) of the Time Synchronization MAC Management Message is transferred from the Downstream Transmission Convergence Sublayer, to the Downstream Physical Media Dependent Sublayer, as described in [J.210].
+
+#### 6.1.3.2 Correction and insertion
+
+The EQAM MUST derive a local DOCSIS timestamp from the DTI Client, specified in [J.211]. The EQAM MUST support either a 10.24 MHz master clock frequency or a 9.216 MHz master clock frequency depending on the region in which it will operate. In the D-MPT mode, the EQAM must be capable of correcting all embedded SYNC messages in the DOCSIS stream. For the DOCSIS PSP mode, the EQAM MUST be capable of inserting DOCSIS SYNC messages based upon its internal timestamp into the downstream MPEG-TS stream within the specifications in 6.1.3.3. In PSP Mode, the EQAM MUST insert the SYNC message starting at the 6th byte of the MPEG-TS frame (the fifth byte would be the MPEG pointer\_field). When referencing a timebase to use for SYNC timestamp insertion or correction, the EQAM MUST utilize a timebase that is delayed by no less than 0 and no more than 100 clock cycles (approximately 10  $\mu\text{s}$ ) of the master clock compared to the time communicated via the DTI Client Test Port output.
+
+This time difference between the time communicated via the DTI Client Test Port output and the time reference applied by an EQAM is expected to be essentially constant. All timing and jitter requirements that exist in this Recommendation and [J.210] still apply. The requirements here do not preclude an EQAM from taking longer than 100 clock cycles to process the DTI conveyed time, but in that case, the EQAM would need to internally adjust the applied timebase such that it is delayed between zero and 100 clock cycles from the DTI conveyed timebase.
+
+When using the D-MPT mode, the M-CMTS Core MUST generate SYNC messages and include them in the D-MPT payload. The M-CMTS Core MUST insert the SYNC message starting at the 6th byte of the MPEG-TS frame (the fifth byte would be the MPEG pointer\_field). This is intended to simplify the EQAM implementation by allowing the EQAM to check only the payload\_unit\_start\_indicator bit and the fifth and sixth byte (which together will contain 0x00C0) of the MPEG-TS packet to locate a DOCSIS SYNC message. Note that the CMTS Timestamp in the SYNC messages generated by the M-CMTS core is not required to accurately reflect the current timestamp received via a DTI Client in the M-CMTS Core. For example, it is permissible for the M-CMTS Core to use a value of zero for the CMTS Timestamp in all SYNC messages. When using the DOCSIS PSP mode, the M-CMTS Core MUST NOT generate SYNC messages as part of the PSP payload.
+
+#### 6.1.3.3 Timestamp jitter
+
+The DOCSIS timestamp jitter MUST be less than 500 ns peak-to-peak at the output of the Downstream Transmission Convergence Sublayer. This jitter is relative to an ideal Downstream Transmission Convergence Sublayer that transfers the MPEG packet data to the Downstream Physical Media Dependent Sublayer with a perfectly continuous and smooth clock at the MPEG packet data rate. Downstream Physical Media Dependent Sublayer processing MUST NOT be considered in timestamp generation and transfer to the Downstream Physical Media Dependent Sublayer.
+
+Thus, any two timestamps N1 and N2 ( $N2 > N1$ ) which were transferred to the Downstream Physical Media Dependent Sublayer at times T1 and T2 respectively must satisfy the following relationship:
+
+$$|(N2 - N1)/f_{\text{CMTS}} - (T2 - T1)| < 500 \times 10^{-9}$$
+
+In the equation, the value of  $(N2 - N1)$  is assumed to account for the effect of rollover of the timebase counter, and  $T1$  and  $T2$  represent time in seconds.  $f_{\text{CMTS}}$  is the actual frequency of the CMTS master timebase and may include a fixed frequency offset from the nominal master clock frequency. This frequency offset is bounded by a requirement further below in this clause.
+
+The jitter includes inaccuracy in timestamp value and the jitter in all clocks. The 500 ns allocated for jitter at the Downstream Transmission Convergence Sublayer output MUST be reduced by any jitter that is introduced by the Downstream Physical Media Dependent Sublayer.
+
+NOTE – Jitter is the error (i.e., measured) relative to the CMTS master clock.
+
+### 6.1.4 Latency and skew requirements
+
+#### 6.1.4.1 Latency
+
+For PSP DEPI sessions, latency is defined as the absolute difference in time from when the last bit of a DEPI packet containing the last bit of a single DOCSIS MAC frame enters the EQAM DEPI port to the time that the first bit of the DOCSIS MAC frame exits the EQAM RFI port. For D-MPT DEPI sessions, latency is defined as the absolute difference in time from when the last bit of a DEPI packet enters the EQAM DEPI port to the time that the first bit of the first MPEG packet contained within said DEPI packet exits the EQAM RFI port. At the EQAM input, the last bit of the arriving DEPI packet is used because the EQAM's layer 2 interface (e.g., GigE Ethernet port) must receive the entire packet before the EQAM can begin processing. At the EQAM output, the first bit of the first MPEG packet (in D-MPT mode) or DOCSIS frame (in PSP mode) inside the DEPI packet is used to guarantee that the data complies with the definition of "isolated packets" (see next paragraph). If this were not done, the measurement could be corrupted by delays incurred due to queuing of data behind other packets destined for the same RF interface. The EQAM SHOULD allow enough buffer memory per QAM channel to buffer at least 20 ms worth of traffic across all L2TPv3 sessions destined for that QAM channel.
+
+In PSP DEPI sessions, the multiple flows supported in the EQAM provide for prioritized access to the modulator. In the absence of higher priority traffic, and regardless of load of lower priority traffic, the EQAM MUST forward isolated packets in each DEPI flow with a latency of less than 500  $\mu\text{s}$  plus the delay of the interleaver. Isolated packets are spaced such that, at the nominal downstream data rate, the EQAM would complete transmission of the current packet before the arrival of the next packet.
+
+#### 6.1.4.2 Skew
+
+Skew is defined as the difference between the maximum latency and the minimum latency through the EQAM, as measured from two reference bits on the network interface to the same bits on two separate RF outputs. Skew is to be measured with the PHY parameters set equal on the QAM Channels under measurement.
+
+The skew between any two bonded QAM Channels within an EQAM MUST be less than 500  $\mu\text{s}$ . The skew requirements for the EQAM are implicitly met when the EQAM meets the latency requirements set out above in 6.1.4.1. This requirement is intended for the transmission of skew sensitive traffic such as bonded traffic.
+
+## 6.2 Networking considerations
+
+### 6.2.1 Per hop behaviour usage
+
+The Per Hop Behaviour Identifier (PHBID) is used by network devices to signal the correct Per Hop Behaviour (PHB) between one another. PHB permits Expedited Forwarding (EF) as described in [RFC-PHBID-EF], Assured Forwarding (AF) as described in [RFC-PHBID-AF], or best effort forwarding as described in [RFC-PHBID-AF] to be used. The M-CMTS Core MUST support the Expedited Forwarding PHBID for PSP mode. The M-CMTS Core MUST support the best effort
+
+PHBID for both DEPI modes. The EQAM MUST support the EF PHBID for PSP mode. The EQAM MUST support the best effort PHBID for both DEPI modes.
+
+The DEPI interface supports multiple traffic types including DOCSIS MAC and DOCSIS data traffic. Within both traffic types, there may be different levels of priority. For PSP operation, the M-CMTS Core SHOULD provide a mechanism to map traffic of different priorities to DEPI flows with different PHB values. The M-CMTS Core SHOULD NOT use the same PHB across multiple DEPI flows within a session.
+
+The CIN should provide the appropriate Per Hop Behaviour for the differentiated traffic types. The level of granularity provided for differentiated traffic is determined by the network operator, but at a minimum, it would be expected that DOCSIS MAP messages and VoIP data traffic are prioritized over best effort data traffic.
+
+The EQAM uses the PHB signalled in the establishment of the DEPI flow when scheduling multiple DEPI PSP flows onto one QAM Channel as described in 6.1.2.
+
+### 6.2.2 DiffServ code point usage
+
+The DSCP is a value located in the 6-bit DiffServ Field of the IP Header. The DSCP of the L2TPv3 packet SHOULD be assigned at the egress of the M-CMTS Core to provide Quality of Service for DEPI traffic within the CIN. The DSCP MAY be used at the ingress of the EQAM.
+
+The M-CMTS Core MUST tag all packets within a DEPI flow of an L2TPv3 session with the same DSCP.
+
+DOCSIS frames encapsulated in L2TPv3 packets may contain IP packets which also have a DSCP assigned. The EQAM is not required to schedule packets based upon the original DSCP contained within the DOCSIS frame.
+
+### 6.2.3 Packet sequencing
+
+For a stream of packets transmitted on a DEPI flow, the packet sequence number will be incremented by one for each packet sent, as described in 8.2 and 8.3. If the EQAM detects a discontinuity in the packet sequence numbers indicating that one or more packets were dropped or delayed, an error is logged and the EQAM SHOULD transfer the current packet to the QAM Channel without waiting for the missing packets. If the EQAM detects a discontinuity in the packet sequence numbers indicating that one or more packets have arrived late, then those packets SHOULD be discarded. The EQAM MUST NOT forward packets which were skipped due to a discontinuity in the sequence numbers. Storing and re-ordering of packets so that they can be delivered to the QAM Channel in the correct sequence is not prohibited by these requirements and the EQAM MAY perform such re-ordering as long as the latency requirements of clause 6.1.4 are met.
+
+### 6.2.4 Network MTU
+
+The network between the M-CMTS Core and the EQAM will have a certain Maximum Transmission Unit. If a maximum size DOCSIS frame were to be tunnelled from the M-CMTS Core to the EQAM without fragmentation, the size of the resulting packet may be greater than the CIN can handle. Both the D-MPT and PSP modes avoid this issue by offering streaming and fragmentation. As such, IP fragmentation is not required. IP fragmentation is also undesirable because the EQAM may forward packets based upon the destination UDP port, and the UDP port is only available in the first IP fragment.
+
+Determining the MTU to use for the L2TPv3 tunnel between the M-CMTS Core and the EQAM is a two-step process. The first step is done as part of L2TPv3 session establishment (see clause 7) using the DEPI MTU AVPs. When the M-CMTS Core starts the session establishment with an ICRQ message, it MUST supply the DEPI Local MTU AVP with a payload size that is the lesser of its receive capabilities and the receive capabilities defined by its lower layer. The receive
+
+capabilities of the M-CMTS Core are defined by its internal constraints, and any configured maximums. The receive capabilities defined by its lower layer is a calculation based on referencing the payload size constraints of the interface below which this tunnel is being created, as defined in A.1. The M-CMTS Core MUST support an MTU size of at least 1500 bytes. The EQAM MUST send L2TPv3 frames with a payload size less than or equal to this maximum. If the EQAM cannot meet this criterion, then it MUST fail session creation by generating a CDN message. The EQAM needs to consider the same criteria in calculating its MTU. The EQAM MUST support an MTU size of at least 1500 bytes, as calculated in A.1. The EQAM MUST insert the DEPI Remote MTU AVP in the ICRP message with its MTU size. The M-CMTS Core MUST send L2TPv3 frames with a payload size less than or equal to this maximum. If the M-CMTS Core cannot meet this criterion, then it MUST fail session creation by generating a CDN message.
+
+The second step is to determine the MTU of the path between the M-CMTS Core and the EQAM. The M-CMTS Core MUST support a mechanism to prevent sending packets larger than the network MTU. This SHOULD be done using Path MTU Discovery, as described in [RFC-MTU]. Clause A.3 gives a brief overview of the Path MTU discovery protocol. Alternatively, this MAY be done via a static configuration option. Both the M-CMTS Core and the EQAM MUST have a way to statically configure an MTU for each L2TPv3 session. To avoid IP fragmentation, the M-CMTS Core and the EQAM MUST set the Don't Fragment bit (DF) in the IPv4 header for all transmissions into the L2TPv3 pseudowire.
+
+## 6.3 System timing considerations
+
+To ensure proper system operation, the M-CMTS Core SHOULD utilize a timebase that is delayed by no less than 0 and no more than 100 clock cycles (approximately 10 µs) of the master clock compared to the time communicated via the DTI Client Test Port output. The M-CMTS Core MUST support either a 10.24 MHz master clock frequency or a 9.216 MHz master clock frequency depending on the region in which it will operate.
+
+This time difference between the time communicated via the DTI Client Test Port output and the time reference applied by an M-CMTS Core is expected to be essentially constant. The requirements here do not preclude an M-CMTS Core from taking longer than 100 clock cycles to process the DTI conveyed time, but in that case, the M-CMTS Core would need to internally adjust the applied timebase such that it is delayed between zero and 100 clock cycles from the DTI conveyed timebase.
+
+# 7 DEPI control plane
+
+NOTE – This clause is normative.
+
+The DEPI control plane is based upon L2TPv3 signalling. The intent of this Recommendation is to follow the provisions of [RFC-L2TPv3]. This clause includes some examples of how L2TPv3 signalling is used, and includes the extensions and interpretations of the [RFC-L2TPv3] specification as it applies to DOCSIS.
+
+All requirements from [RFC-L2TPv3] MUST be met by both the M-CMTS Core and the EQAM unless this Recommendation explicitly states that a particular requirement from [RFC-L2TPv3] is not required.
+
+## 7.1 Topology
+
+![Diagram of L2TP topology for modular CMTS showing the flow from a regional area network through an M-CMTS core and Edge QAM to a home network via a CM.](043e64d41a3368d138ace3816fd26469_img.jpg)
+
+The diagram illustrates the L2TP topology for a modular CMTS. It shows a sequence of components from left to right: a 'Regional area network' (cloud labeled 'L2 or L3'), an 'M-CMTS core' (containing a 'LAC'), a 'Converged interconnect network' (cloud labeled 'L2 or L3'), an 'Edge QAM' (containing a 'LAC'), a 'CM' (cable modem), and a 'Home network' (house icon). A 'Pseudo wire' is indicated by a double-headed arrow between the 'LAC' in the M-CMTS core and the 'LAC' in the Edge QAM. A 'DOCSIS service' is indicated by a single-headed arrow pointing from the 'Edge QAM' to the 'CM'. The diagram is labeled 'J.212(06)\_F7-1' in the bottom right corner.
+
+Diagram of L2TP topology for modular CMTS showing the flow from a regional area network through an M-CMTS core and Edge QAM to a home network via a CM.
+
+**Figure 7-1/J.212 – L2TP topology for modular CMTS**
+
+Figure 7-1 shows how the Modular CMTS architecture maps to L2TP topology. In L2TPv3 nomenclature, the M-CMTS Core and the EQAM are known as a L2TP Access Concentrator (LAC). The M-CMTS Core and the EQAM are considered as peers and may also be referred to as L2TP nodes or as L2TP Control Connection Endpoints (LCCE). For the purposes defined in this Recommendation, each LCCE is identified on the network by a single IP address. The connections between two LCCEs are known as Pseudo wires (PW).
+
+The L2TP supports both a data path and an inband control path. In L2TPv3 nomenclature, data messages are sent on the data channel, and control messages are sent on the control connection.
+
+First a control connection is established between the two LCCEs, then a session is established. An L2TP session is established before L2TP begins to forward session frames for data. Multiple sessions may be bound to a single control connection.
+
+## 7.2 Addressing
+
+The M-CMTS Core SHOULD use the IP Address of the EQAM and the TSID of the QAM Channel to uniquely identify a QAM Channel within an EQAM during initial configuration.
+
+The M-CMTS Core MUST establish at most one control connection for each LCCE pair. This control connection will manage all sessions between the M-CMTS Core and the EQAM. If the UDP Header is used, the control connection SHOULD use UDP port 1701.
+
+![Diagram illustrating the DEPI addressing hierarchy between an M-CMTS core and an EQAM. The M-CMTS core contains two sessions, Session A and Session B. Session A has two flows, flow 1 and flow 2. Session B also has two flows, flow 1 and flow 2. The EQAM contains two sessions, Session A and Session B. Session A has two flows, flow 1 and flow 2. Session B also has two flows, flow 1 and flow 2. Control connections (per LCCE pair) are shown between the M-CMTS core and the EQAM. DEPI sessions (per channel) are shown between the M-CMTS core and the EQAM. Data flows (DSCPx and DSCPy) are shown between the M-CMTS core and the EQAM. The EQAM is connected to two QAM channels.](8c348bf9c2c81b018017ae1d19506a9a_img.jpg)
+
+The diagram shows the hierarchy of DEPI addressing between an M-CMTS core and an EQAM. On the left, the M-CMTS core contains two sessions: Session A and Session B. Session A includes flow 1 and flow 2. Session B includes flow 1 and flow 2. On the right, the EQAM contains two sessions: Session A and Session B. Session A includes flow 1 and flow 2. Session B includes flow 1 and flow 2. A control connection (per LCCE pair) is shown between the M-CMTS core and the EQAM. DEPI sessions (per channel) are shown between the M-CMTS core and the EQAM. Data flows (DSCPx and DSCPy) are shown between the M-CMTS core and the EQAM. The EQAM is connected to two QAM channels, indicated by dashed arrows on the right side of the EQAM box. The text 'J.212(06)\_F7-2' is located at the bottom right of the diagram.
+
+Diagram illustrating the DEPI addressing hierarchy between an M-CMTS core and an EQAM. The M-CMTS core contains two sessions, Session A and Session B. Session A has two flows, flow 1 and flow 2. Session B also has two flows, flow 1 and flow 2. The EQAM contains two sessions, Session A and Session B. Session A has two flows, flow 1 and flow 2. Session B also has two flows, flow 1 and flow 2. Control connections (per LCCE pair) are shown between the M-CMTS core and the EQAM. DEPI sessions (per channel) are shown between the M-CMTS core and the EQAM. Data flows (DSCPx and DSCPy) are shown between the M-CMTS core and the EQAM. The EQAM is connected to two QAM channels.
+
+**Figure 7-2/J.212 – DEPI addressing hierarchy**
+
+The M-CMTS Core MUST support the creation of a single session per QAM channel. The EQAM MUST support a single session per QAM channel. Each DEPI session uses one of the Pseudowire types described in 7.5.1.1. Per [RFC-L2TPv3], both the M-CMTS Core and the EQAM assign a unique L2TPv3 session ID for each session. The M-CMTS Core MUST NOT attempt to create a session to a QAM channel for which the M-CMTS Core already has an active session. Unless specifically configured otherwise, the EQAM MUST reject an attempt to establish a session to a QAM channel for which a session has already been established.
+
+The M-CMTS Core MAY create multiple PSP flows per session. Different EQAM implementations may support different numbers of PSP flows on any given DEPI session, which is described further in 6.1. During L2TPv3 session setup, the EQAM MUST assign each flow a unique flow ID. Reassembly, if applicable, is done per flow ID at the EQAM. The EQAM MAY assign each flow a unique UDP Destination Port. The M-CMTS Core MUST address DEPI packets using the UDP Destination Port (if the UDP header is used), L2TPv3 Session ID, and flow ID assigned by the EQAM. This is shown in Figure 7-2 and in more detail in Figure 7-3.
+
+![Diagram of DEPI addressing hierarchy showing flows being reassembled into priority queues and then mapped to a QAM channel for transmission.](69b7bd65e85cdef6fdd7fb0a8194257c_img.jpg)
+
+The diagram illustrates the DEPI addressing hierarchy. On the left, multiple data flows are shown: Flow A (Dest. UDP L, DSCP X), Flow B (Dest. UDP M, DSCP Y), Flow C (Dest. UDP N, DSCP Z), and an Unused flow. Each flow has a corresponding 'Flow Receive/Reassemble Queue' (Queue #1, #2, #3, and #N). These queues feed into two 'Priority Queue' blocks. 'Priority Queue 1' handles Flow A and Flow B (UDP Ports: (L,M)). 'Priority Queue 2' handles Flow C (UDP Ports: (N)). Both priority queues feed into a large 'QAM Channel' block. Inside the QAM Channel, a dashed box lists 'QAM channel attributes': Pseudowire Type, Session ID (L2TPv3 Data Session), and TSID. The QAM Channel output goes to a 'Packet scheduler', which then connects to 'Transmission convergence', which finally outputs to 'DRFI'. The diagram is labeled 'J.212(06)\_F7-3' at the bottom right.
+
+Diagram of DEPI addressing hierarchy showing flows being reassembled into priority queues and then mapped to a QAM channel for transmission.
+
+**Figure 7-3/J.212 – DEPI addressing hierarchy**
+
+## 7.3 Control message format
+
+The format of a DEPI Control Packet, as shown in Figures 7-4 and 7-5, is based on [RFC-L2TPv3], with extensions for DOCSIS. The fields which are common with the DEPI Data Packet are described in 8.1. Fields which are used differently or are new are described below. Unless otherwise indicated, all values are shown in decimal notation.
+
+The choice of using or not using a UDP header is done through system configuration and is not a negotiated DEPI parameter. The UDP version of DEPI is intended for systems which use the UDP port to map flows to a QAM Channel within an EQAM. The non-UDP version of DEPI is intended for systems which use the L2TPv3 Session ID to map flows to a QAM Channel within an EQAM.
+
+The M-CMTS Core MUST support DEPI with a UDP header. The M-CMTS MAY support DEPI without a UDP header. The EQAM MAY support DEPI without a UDP header. The EQAM MUST support DEPI with a UDP header.
+
+### 7.3.1 Control message with a UDP header
+
+![](5414f65867392f05ba0063b208eeb5e1_img.jpg)
+
+0 7 15 23 31
+
+|             |  |  |  |  |  |  |  |    |  |  |  |  |  |  |  |
+|-------------|--|--|--|--|--|--|--|----|--|--|--|--|--|--|--|
+| DA          |  |  |  |  |  |  |  |    |  |  |  |  |  |  |  |
+| DA          |  |  |  |  |  |  |  | SA |  |  |  |  |  |  |  |
+| SA          |  |  |  |  |  |  |  |    |  |  |  |  |  |  |  |
+| Length/Type |  |  |  |  |  |  |  |    |  |  |  |  |  |  |  |
+
+Ethernet 802.3 Header (14 bytes)
+
+|               |      |                 |  |  |  |  |  |                        |  |  |  |  |  |  |  |
+|---------------|------|-----------------|--|--|--|--|--|------------------------|--|--|--|--|--|--|--|
+| User Priority | C FI | VLAN Identifier |  |  |  |  |  | MAC Client Length/Type |  |  |  |  |  |  |  |
+|---------------|------|-----------------|--|--|--|--|--|------------------------|--|--|--|--|--|--|--|
+
+Ethernet 802.1Q Optional Header (4 bytes)
+
+|                        |     |          |  |          |              |  |  |                 |                 |  |  |  |  |  |  |
+|------------------------|-----|----------|--|----------|--------------|--|--|-----------------|-----------------|--|--|--|--|--|--|
+| Version                | IHL | DS Field |  | ECN      | Total Length |  |  |                 |                 |  |  |  |  |  |  |
+| Identification         |     |          |  |          |              |  |  | Flags           | Fragment Offset |  |  |  |  |  |  |
+| Time to Live           |     |          |  | Protocol |              |  |  | Header Checksum |                 |  |  |  |  |  |  |
+| Source IP Address      |     |          |  |          |              |  |  |                 |                 |  |  |  |  |  |  |
+| Destination IP Address |     |          |  |          |              |  |  |                 |                 |  |  |  |  |  |  |
+
+IPv4 Header (20 bytes)
+
+|             |  |  |  |  |  |  |  |                  |  |  |  |  |  |  |  |
+|-------------|--|--|--|--|--|--|--|------------------|--|--|--|--|--|--|--|
+| Source Port |  |  |  |  |  |  |  | Destination Port |  |  |  |  |  |  |  |
+| Length      |  |  |  |  |  |  |  | Checksum         |  |  |  |  |  |  |  |
+
+UDP Header (8 bytes)
+
+|                       |   |   |   |   |   |   |   |    |   |     |        |  |  |  |  |
+|-----------------------|---|---|---|---|---|---|---|----|---|-----|--------|--|--|--|--|
+| T                     | L | X | X | S | X | X | X | X  | X | Ver | Length |  |  |  |  |
+| Control Connection ID |   |   |   |   |   |   |   |    |   |     |        |  |  |  |  |
+| Ns                    |   |   |   |   |   |   |   | Nr |   |     |        |  |  |  |  |
+
+L2TPv3 Control Header (12 bytes)
+
+|                              |   |      |  |        |  |  |  |                    |  |  |  |  |  |  |  |
+|------------------------------|---|------|--|--------|--|--|--|--------------------|--|--|--|--|--|--|--|
+| M                            | H | Resv |  | Length |  |  |  | Vendor ID          |  |  |  |  |  |  |  |
+| Attribute Type               |   |      |  |        |  |  |  | Attribute Value... |  |  |  |  |  |  |  |
+| ...(until length is reached) |   |      |  |        |  |  |  |                    |  |  |  |  |  |  |  |
+
+List of AVPs N \*(6+ bytes)
+
+|     |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
+|-----|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--|
+| CRC |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
+|-----|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--|
+
+CRC (4 bytes)
+
+J.212(06)\_F7-4
+
+Figure 7-4/J.212 – DEPI control packet with UDP
+
+### 7.3.2 Control message without a UDP header
+
+![Diagram of DEPI control packet without UDP header showing various headers and their bit/byte positions.](5d3455c6c2a37cb3aff761fedeb8644e_img.jpg)
+
+The diagram illustrates the structure of a DEPI control packet without a UDP header. It shows the following headers and their fields:
+
+- Ethernet 802.3 Header (14 bytes):** Contains DA (Destination Address), SA (Source Address), and Length/Type. Bit positions 0, 7, 15, 23, and 31 are marked at the top.
+- Ethernet 802.1Q Optional Header (4 bytes):** Contains User Priority, CFI, VLAN Identifier, and MAC Client Length/Type.
+- IPv4 Header (20 bytes):** Contains Version, IHL, DS Field, ECN, Total Length, Identification, Flags, Fragment Offset, Time to Live, Protocol (115), Header Checksum, Source IP Address, and Destination IP Address.
+- L2TPv3 Control Header (16 bytes):** Contains Session ID (0), a series of flags (T, L, X, S, X, X, X, X, X, X, X, X), Ver, Length, Control Connection ID, Ns, and Nr.
+- List of AVPs (N\*(6+ bytes)):** Contains M, H, Resv, Length, Vendor ID, Attribute Type, and Attribute Value... (until length is reached).
+- CRC (4 bytes):** Contains the CRC field.
+
+J.212(06)\_F7-5
+
+Diagram of DEPI control packet without UDP header showing various headers and their bit/byte positions.
+
+Figure 7-5/J.212 – DEPI control packet without UDP
+
+### 7.3.3 Common headers for control and data messages
+
+#### 7.3.3.1 Ethernet 802.3 header
+
+The Ethernet header is defined by [IEEE-802.3]. The Ethernet Destination Address is an individual address. Operation with DEPI over Ethernet group addresses is not specified at this time. The Ethernet Destination Address may be locally or globally administered.
+
+Upon transmission of this frame by the M-CMTS Core, the Ethernet Destination Address will be the Ethernet address of the EQAM or of the next hop router. Upon reception of this frame by the EQAM, the Ethernet Source Address will be the Ethernet address of the output port of the M-CMTS Core or of the previous hop router.
+
+If the networking interface is Ethernet, the M-CMTS Core MUST support the Ethernet header. If the networking interface is Ethernet, the EQAM MUST support the Ethernet header. If another physical layer interface is used instead of Ethernet, then the Ethernet headers would be replaced with the header format pertaining to that physical layer.
+
+#### 7.3.3.2 Ethernet 802.1Q header
+
+The Ethernet 802.1Q header is defined by [IEEE-802.1Q]. The use of this header is optional and provides frame prioritization and VLAN support at layer 2. The M-CMTS Core MUST be able to
+
+support the Ethernet 802.1Q header. The M-CMTS Core SHOULD support mapping of 802.1Q user priority of tunnelled packets based on the DSCP value of a tunnel's IP packet. The EQAM SHOULD support the Ethernet 802.1Q header.
+
+#### 7.3.3.3 IPv4 header
+
+The IP header is defined by [RFC-IP]. The IP Source Address is an IP address belonging to the M-CMTS Core. Currently, the IP Destination Address is unicast and is an IP Address belonging to the EQAM. Operation with DEPI over IP Multicast is not specified at this time.
+
+For implementation considerations and for coexistence with network policies that are not amenable to IP fragmentation, EQAMs are not required to perform IP reassembly. The M-CMTS Core MUST NOT use IP fragmentation. The M-CMTS Core MUST set the IP DF (don't fragment) bit.
+
+The M-CMTS Core MUST support a configurable 6-bit Differentiated Services Code Point (DSCP) to be used in the DS Field. The DS Field and DSCP are described in further detail by [RFC-DSCP-1] (RFC 2983) and [RFC-DSCP-2] (RFC 3260).
+
+The M-CMTS Core MUST support the IPv4 header. The EQAM MUST support the IPv4 header.
+
+#### 7.3.3.4 UDP header
+
+The UDP header is defined by [RFC-UDP]. The value of the UDP Source Port and the UDP Destination Port is determined through the L2TPv3 control plane between the M-CMTS Core and the EQAM. This value SHOULD conform to [IANA-PORTS].
+
+When transmitting packets, both the EQAM and M-CMTS Core MUST support the generation of UDP checksums as defined in [RFC-UDP]. The sender MAY choose to set the UDP checksum to 0 for L2TPv3 data messages. This value is reserved by [RFC-UDP] to mean no checksum has been calculated. The sender MUST NOT set the UDP checksum to 0 for L2TPv3 control messages. The receiver MUST support validation of the UDP checksum field, as per [RFC-UDP].
+
+The M-CMTS Core MUST support the UDP header. The EQAM MUST support the UDP header.
+
+#### 7.3.3.5 CRC
+
+The CRC is CRC-32 and is defined by [IEEE-802.3].
+
+The M-CMTS Core MUST support the CRC field. The EQAM MUST support the CRC field.
+
+### 7.3.4 Specific headers for control messages
+
+#### 7.3.4.1 L2TPv3 control header
+
+These fields are defined in [RFC-L2TPv3] and are repeated here for reference. The fields have the following significance:
+
+- T** Type bit. The T bit MUST be set to 1, indicating that this is a control message.
+- L** Length bit. The L bit MUST be set to 1, indicating that the Length field is present.
+- S** Sequence bit. The S bit MUST be set to 1 indicating that sequence numbers (Ns and Nr) are present.
+- X** Reserved bits. All reserved bits MUST be set to 0 on outgoing messages and ignored on incoming messages.
+- Ver** Version. 4 bits. Set to 3.
+- Length** 2 bytes. The Length field indicates the total length of the message in octets, always calculated from the start of the control message header itself, beginning with the T bit. It does not include the Session ID (shown in Figure 7-5) when present.
+- CCID** Control Connection Identifier. 4 bytes. Negotiated per control connection.
+
+**Ns** Sending Sequence Number. 2 bytes. Indicates sending sequence of this control message.
+
+**Nr** Received Sequence Number. 2 bytes. Indicates next expected received sequence number.
+
+#### 7.3.4.2 Attribute Value Pairs (AVP)
+
+There can be one or more attribute value pairs (AVPs) per DEPI control message. The fields have the following significance:
+
+**M** Mandatory bit. If this bit is set to a 1 and this AVP is rejected, the control connection or session setup in which the AVP is carried will be torn down.
+
+**H** Hidden bit. This bit is set to a 1 when the contents of the AVP message are encrypted and a 0 when the contents of the AVP message are not encrypted. Encryption of AVP messages is not required for DEPI.
+
+**Resv** Reserved. 4 bits. Set to all zeros on transmit. Ignored on receive.
+
+**Length** 10 bits. Equal to the length of the attribute value field plus 6 bytes.
+
+**Vendor ID** 2 bytes. For AVPs defined by [RFC-L2TPv3], this field is set to 0. For AVPs defined by this Recommendation, this field is set to the IANA assigned vendor ID of 4491 (0x118B). For AVPs defined outside the scope of this Recommendation, this field may be set to a vendor specific ID.
+
+**Attribute Type** 2 bytes.
+
+**Attribute Value** N bytes.
+
+**Reserved** 8 bits. If an AVP has a reserved field, the bits in this field should be set to 0 on transmit and ignored on the receive.
+
+If an LCCE receives an AVP with a Vendor ID that it does not recognize, it MUST silently discard the AVP or tear down the session depending on the value of the Mandatory bit.
+
+## 7.4 Signalling
+
+The supported L2TPv3 messages for the DEPI control plane are shown in Table 7-1:
+
+**Table 7-1/J.212 – DEPI control messages**
+
+| #                                    | Mnemonic | Name                                 |
+|--------------------------------------|----------|--------------------------------------|
+| <b>Control connection management</b> |          |                                      |
+| 1                                    | SCCRQ    | Start-Control-Connection-Request     |
+| 2                                    | SCCRP    | Start-Control-Connection-Reply       |
+| 3                                    | SCCCN    | Start-Control-Connection-Connected   |
+| 4                                    | StopCCN  | Stop-Control-Connection-Notification |
+| 6                                    | HELLO    | Hello                                |
+| 20                                   | ACK      | Explicit Acknowledgement             |
+| <b>Session management</b>            |          |                                      |
+| 10                                   | ICRQ     | Incoming-Call-Request                |
+| 11                                   | ICRP     | Incoming-Call-Reply                  |
+| 12                                   | ICCN     | Incoming-Call-Connected              |
+| 14                                   | CDN      | Call-Disconnect-Notify               |
+| 16                                   | SLI      | Set Link Info                        |
+
+L2TPv3 outgoing call messages (OCRQ, OCRP, OCCN) and the WAN-Error-Notify (WEN) messages are not required to be supported.
+
+There is a reliable control message delivery mechanism that is accomplished either by sending an Explicit Acknowledgement (ACK) message after any of the control messages or by piggybacking an acknowledgment with the Nr and Ns fields in a later control message. If Control Messages are not acknowledged within the time Control Message Timeout (refer to Annex B), then the Control Message MUST be retransmitted up to the value of Control Message Retry Count (refer to Annex B). For example, the Control Message must be retransmitted a total of 10 times using an exponential back-off value starting at 1 second and growing to a maximum value of 8 seconds.
+
+NOTE – There will be 7 intervals of 8 seconds in this scheme.
+
+Control message authentication MAY be supported. If Control Message Authentication is supported, the methods described in [RFC-L2TPv3], section 5.4.1, should be followed.
+
+The following flow diagrams show typical DEPI message exchanges along with the required AVPs from L2TPv3 and DEPI. Optional AVPs are not shown but may also be present.
+
+### 7.4.1 Control connection signalling
+
+#### 7.4.1.1 Control connection setup
+
+![Sequence diagram showing DEPI control connection setup between M-CMTS core and EQAM.](8658cfab6a458b4a80ab2e384c61ff89_img.jpg)
+
+```
+sequenceDiagram
+    participant M-CMTS core
+    participant EQAM
+    Note right of EQAM: J.212(06)_F7-6
+    M-CMTS core->>EQAM: SCCRQ {Message Type, Host Name, Router ID, Assigned Control Connection ID, Pseudowire Capabilities List}
+    EQAM-->>M-CMTS core: SCCRP {Message Type, Host Name, Router ID, Assigned Control Connection ID, Pseudowire Capabilities List}
+    M-CMTS core->>EQAM: SCCN {Message Type}
+```
+
+The diagram illustrates the control connection setup between an M-CMTS core and an EQAM. It consists of three message exchanges: 1. The M-CMTS core sends an SCCRQ message to the EQAM. 2. The EQAM responds with an SCCRP message. 3. The M-CMTS core sends an SCCN message to the EQAM. The messages contain various attributes like Message Type, Host Name, Router ID, Assigned Control Connection ID, and Pseudowire Capabilities List. A label 'J.212(06)\_F7-6' is present at the bottom right of the diagram.
+
+Sequence diagram showing DEPI control connection setup between M-CMTS core and EQAM.
+
+Figure 7-6/J.212 – DEPI control connection setup
+
+In order to tunnel DOCSIS frames over IP using L2TPv3, an L2TPv3 Control Connection is first established as described in [RFC-L2TPv3]. Establishment of the control connection involves an exchange of AVPs that identifies the peer and its capabilities. Each control connection has a Control Connection ID which is assigned by the recipient, and negotiated with Connection ID AVPs during the creation of a control connection.
+
+The M-CMTS Core MUST support the ability to initiate control connection signalling (L2TPv3 caller). The EQAM MUST support the ability to receive incoming control connection requests from the M-CMTS Core (L2TPv3 callee). Establishment of control connections by the EQAM is not required for DEPI and is outside the scope of this Recommendation.
+
+#### 7.4.1.2 Control connection teardown
+
+![](85e2327652d513a7fee8fdbf97ad06f1_img.jpg)
+
+```
+sequenceDiagram
+    participant M as M-CMTS core
+    participant E as EQAM
+    Note over M,E: Scenario 1: Initiated by M-CMTS core
+    M->>E: StopCCN {Message Type, Result Code, DEPI Result Code}
+    rect rgb(255, 255, 255)
+    Note right of M: Clean Up
+    Note left of E: Wait
+    Note left of E: Clean Up
+    end
+    Note over M,E: ------------------------------------------------------------------
+    Note over M,E: Scenario 2: Initiated by EQAM
+    E->>M: StopCCN {Message Type, Result Code, DEPI Result Code}
+    rect rgb(255, 255, 255)
+    Note right of M: Wait
+    Note right of M: Clean Up
+    Note left of E: Clean Up
+    end
+```
+
+J.212(06)\_F7-7
+
+**Figure 7-7/J.212 – DEPI control connection teardown**
+
+Control connection teardown may be initiated by either LCCE and is accomplished by sending a single StopCCN control message. An implementation may shut down an entire control connection and all sessions associated with the control connection by sending the StopCCN. Thus, it is not necessary to clear each session individually when tearing down the whole control connection. The peer receiving the StopCCN message MUST maintain session and control state for a period of time equal to StopCCN Timeout (Annex B) after acknowledging the StopCCN. This provision is for managing lost acknowledgments.
+
+#### 7.4.1.3 Control connection keep-alive
+
+![Sequence diagram for DEPI keep-alive between M-CMTS core and EQAM.](339be989b91d5b1e73e5ecdc8401ca75_img.jpg)
+
+The diagram illustrates the keep-alive mechanism for the control connection. It features two vertical lifelines: 'M-CMTS core' on the left and 'EQAM' on the right. A dashed horizontal line separates the two phases of the process. In the top phase, a box labeled 'Hello Timeout expires' is on the M-CMTS core lifeline, and an arrow labeled 'Hello {Message Type}' points from it to the EQAM lifeline. In the bottom phase, a box labeled 'Hello Timeout expires' is on the EQAM lifeline, and an arrow labeled 'Hello {Message Type}' points from it back to the M-CMTS core lifeline. The text 'J.212(06)\_F7-8' is located at the bottom right of the diagram.
+
+Sequence diagram for DEPI keep-alive between M-CMTS core and EQAM.
+
+Figure 7-8/J.212 – DEPI keep-alive
+
+A periodic keep-alive for the control connection is implemented by sending a Hello message if a period of time known as the Hello Timeout (refer to Annex A) has passed without receiving any message (data or control) from the peer.
+
+### 7.4.2 Session signalling
+
+#### 7.4.2.1 Session setup
+
+![Sequence diagram for DEPI session setup between M-CMTS core and EQAM.](ac31fdfebb9751f7f10416dfe33bc872_img.jpg)
+
+The diagram shows the session setup process between 'M-CMTS core' (left) and 'EQAM' (right). It consists of three message exchanges: 1) An arrow from M-CMTS core to EQAM labeled 'ICRQ {Message Type, Serial Number, Local Session ID, Remote Session ID, Remote End ID, Pseudowire Type, L2-Specific Sublayer, Circuit Status, DEPI Resource Allocation Request, DEPI Local MTU, DEPI SYNC Control}'. 2) A return arrow from EQAM to M-CMTS core labeled 'ICRP {Message Type, Local Session ID, Remote Session ID, L2-Specific Sublayer, Data Sequencing, Circuit Status, DEPI Resource Allocation Reply, EQAM Capabilities, DEPI Remote MTU, DEPI QAM Channel Parameters Read}'. 3) A final arrow from M-CMTS core to EQAM labeled 'ICCN {Message Type, Local Session ID, Remote Session ID, L2-Specific Sublayer, DEPI QAM Channel Parameters Write}'. The text 'J.212(06)\_F7-9' is at the bottom right.
+
+Sequence diagram for DEPI session setup between M-CMTS core and EQAM.
+
+Figure 7-9/J.212 – DEPI session setup
+
+After successful control connection establishment, individual sessions may be created. Each session corresponds to a single data stream between the two LCCes. In addition to the mandatory and optional AVPs in [RFC-L2TPv3], the following DEPI specific AVPs are used as part of the session setup.
+
+ICRQ contains the Remote End ID AVP which contains the TSID of the QAM Channel for which the session is intended.
+
+ICRP contains the Remote Session AVP which indicates the session ID that the EQAM wants to use. ICRP also contains a suite of QAM Channel AVPs (refer to 7.5.2) which indicate the EQAM's current configuration, which parameters can be changed, EQAM capabilities, and assigned values such as the UDP port values. If these values are not acceptable to the M-CMTS Core, the M-CMTS Core will return a CDN message with the appropriate error code.
+
+ICCN contains the parameters that the M-CMTS Core wants to change. If these parameters are acceptable to the EQAM, the EQAM will return an ACK (either explicit or implicit). If these parameters are not acceptable to the EQAM, the EQAM will return a CDN message with the appropriate error code.
+
+The receipt and processing of the ICCN triggers the initiation of data forwarding in the EQAM for the session. The EQAM MUST NOT transmit data on the QAM channel until the session is configured according to the parameters in the ICCN message. The EQAM SHOULD NOT buffer data while the session is being configured.
+
+The M-CMTS Core MUST support the ability to generate session establishment signalling. The EQAM MUST support the ability to receive incoming session establishment requests from the M-CMTS Core. Establishment of L2TP sessions by the EQAM is outside the scope of this Recommendation.
+
+#### 7.4.2.2 Session teardown
+
+![Sequence diagram of DEPI session teardown between M-CMTS core and EQAM.](fb18a83d10ebdad8e3e5ea2e86b36136_img.jpg)
+
+The diagram illustrates the sequence of messages for a DEPI session teardown between an M-CMTS core and an EQAM. The process is as follows:
+
+- The M-CMTS core sends a **CDN {Message Type, Result Code, Local Session ID, Remote Session ID, DEPI Result Code}** message to the EQAM.
+- Upon receiving the CDN message, both the M-CMTS core and the EQAM perform a **Clean Up** operation.
+- After the cleanup, the EQAM sends a **CDN {Message Type, Result Code, Local Session ID, Remote Session ID, DEPI Result Code}** message back to the M-CMTS core.
+- Upon receiving this second CDN message, both the M-CMTS core and the EQAM perform another **Clean Up** operation.
+
+A dashed horizontal line separates the two cleanup phases. The diagram is labeled J.212(06)\_F7-10 at the bottom right.
+
+Sequence diagram of DEPI session teardown between M-CMTS core and EQAM.
+
+Figure 7-10/J.212 – DEPI session teardown
+
+Session teardown may be initiated by either LCCE and is accomplished by sending a single CDN control message. An implementation may shut down an entire control connection and all sessions associated with the control connection by sending the StopCCN. Thus, it is not necessary to clear each session individually when tearing down the whole control connection.
+
+#### 7.4.2.3 Session updates
+
+![Sequence diagram showing DEPI session updates between M-CMTS core and EQAM.](02bb4edc0dbdf4f0749ffd3e0ea2805c_img.jpg)
+
+The diagram illustrates the interaction between the M-CMTS core and the EQAM for session updates. It is divided into two parts by a dashed horizontal line. In the top part, a box labeled 'Configuration change' is on the M-CMTS core side, and an arrow labeled 'SLI {Message Type, Local Session ID, Remote Session ID}' points from the M-CMTS core to the EQAM. In the bottom part, a box labeled 'Configuration change' is on the EQAM side, and an arrow labeled 'SLI {Message Type, Local Session ID, Remote Session ID}' points from the EQAM to the M-CMTS core. The text 'J.212(06)\_F7-11' is located at the bottom right of the diagram.
+
+Sequence diagram showing DEPI session updates between M-CMTS core and EQAM.
+
+Figure 7-11/J.212 – DEPI session updates
+
+If there is a configuration change to one of the EQAM parameters which is described by a DEPI AVP, the M-CMTS Core MUST send the updated AVP to the EQAM with the Set-Link-Info (SLI) message. If there is a configuration change to one of the EQAM parameters which is described by a DEPI AVP, the EQAM MUST send the updated AVP to the M-CMTS Core using an SLI message.
+
+### 7.4.3 Required and optional AVPs
+
+In addition to the mandatory and optional AVPs listed in [RFC-L2TPv3] and modified by Table 7-3, the following DEPI AVPs listed in Table 7-2 MUST be present in the DEPI control message if mandatory, and MAY be present in DEPI control messages if optional.
+
+**Table 7-2/J.212 – DEPI mandatory and optional AVPs**
+
+| <b>DEPI control message</b> | <b>DEPI mandatory AVPs</b>                                                                                                                                                                                                                                                       | <b>DEPI optional AVPs</b>                                                                                                                                                                                                                    |
+|-----------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| ICRQ                        | DEPI Resource Allocation Request<br>DEPI Local MTU<br>DS QAM Channel DOCSIS SYNC Control                                                                                                                                                                                         | Local UDP Port                                                                                                                                                                                                                               |
+| ICRP                        | DEPI Resource Allocation Reply<br>DEPI Remote MTU<br>EQAM Capabilities<br>DS QAM Channel Frequency<br>DS QAM Channel Power<br>DS QAM Channel Modulation<br>DS QAM Channel J.83 Annex<br>DS QAM Channel Symbol Rate<br>DS QAM Channel Interleaver Depth<br>DS QAM Channel RF Mute | Downstream QAM Channel TSID Group                                                                                                                                                                                                            |
+| ICCN                        |                                                                                                                                                                                                                                                                                  | DS QAM Channel Frequency<br>DS QAM Channel Power<br>DS QAM Channel Modulation<br>DS QAM Channel J.83 Annex<br>DS QAM Channel Symbol Rate<br>DS QAM Channel Interleaver Depth<br>DS QAM Channel RF Mute                                       |
+| CDN                         |                                                                                                                                                                                                                                                                                  | DEPI Result Code                                                                                                                                                                                                                             |
+| SLI                         |                                                                                                                                                                                                                                                                                  | DS QAM Channel DOCSIS SYNC Control<br>DS QAM Channel Frequency<br>DS QAM Channel Power<br>DS QAM Channel Modulation<br>DS QAM Channel J.83 Annex<br>DS QAM Channel Symbol Rate<br>DS QAM Channel Interleaver Depth<br>DS QAM Channel RF Mute |
+
+## 7.5 AVP definitions
+
+### 7.5.1 Conventional L2TPv3 AVPs
+
+The AVP types from [RFC-L2TPv3] and [RFC-L2TP-DSCP] that are supported as part of this Recommendation are shown in Table 7-3.
+
+**Table 7-3/J.212 – DEPI supported L2TPv3 AVPs**
+
+| Attribute type | Control, Session | Description                          | Required | Not required |
+|----------------|------------------|--------------------------------------|----------|--------------|
+| 0              | C, S             | Message Type                         | ●        |              |
+| 1              | S                | Result Code                          | ●        |              |
+| 5              | C, S             | Control/Session Tie Breaker          |          | ●            |
+| 7              | C                | Host Name                            | ●        |              |
+| 8              | C                | Vendor Name                          |          | ●            |
+| 10             | C                | Receive Window Size                  |          | ●            |
+| 15             | S                | Serial Number                        | ●        |              |
+| 25             | S                | Physical Channel ID                  |          | ●            |
+| 34             | S                | Circuit Errors                       |          | ●            |
+| 36             | C, S             | Random Vector                        |          | ●            |
+| 47             | C                | Control Connection DSCP              |          | ●            |
+| 48             | S                | Session DSCP                         |          | ●            |
+| 58             | C, S             | Extended Vendor ID AVP               |          | ●            |
+| 59             | C, S             | Message Digest                       |          | ●            |
+| 60             | C                | Router ID                            | ●        |              |
+| 61             | C                | Assigned Control Connection ID       | ●        |              |
+| 62             | C                | Pseudowire Capabilities List         | ●        |              |
+| 63             | S                | Local Session ID                     | ●        |              |
+| 64             | S                | Remote Session ID                    | ●        |              |
+| 65             | S                | Assigned Cookie                      |          | ●            |
+| 66             | S                | Remote End ID                        | ●        |              |
+| 68             | S                | Pseudowire Type                      | ●        |              |
+| 69             | S                | L2-Specific Sublayer                 | ●        |              |
+| 70             | S                | Data Sequencing                      | ●        |              |
+| 71             | S                | Circuit Status                       | ●        |              |
+| 72             | C                | Preferred Language                   |          | ●            |
+| 73             | C                | Control Message Authentication Nonce |          | ●            |
+| 74             | S                | Tx Connect Speed                     |          | ●            |
+| 75             | S                | Rx Connect Speed                     |          | ●            |
+
+Conventional AVPs whose usage is specific to DEPI are described below. A more complete description as well as requirements for the conventional AVPs is in [RFC-L2TPv3].
+
+#### 7.5.1.1 Message type (All messages)
+
+|                    |   |      |  |            |              |    |               |    |
+|--------------------|---|------|--|------------|--------------|----|---------------|----|
+| 0                  |   | 7    |  | 15         |              | 23 |               | 31 |
+| M                  | H | Resv |  | Length = 8 |              |    | Vendor ID = 0 |    |
+| Attribute Type = 0 |   |      |  |            | Message Type |    |               |    |
+
+**Figure 7-12/J.212 – Message type AVP**
+
+This identifies the particular L2TPv3 Control Message. It is always the first AVP.
+
+#### 7.5.1.2 Result code (StopCCN, CDN)
+
+![](95e259e8cb3519025066052af263f8c0_img.jpg)
+
+|                              |   |      |                       |  |               |  |                   |  |
+|------------------------------|---|------|-----------------------|--|---------------|--|-------------------|--|
+| 0                            | 7 |      | 15                    |  | 23            |  | 31                |  |
+| M                            | H | Resv | Length = 8 + N        |  | Vendor ID = 0 |  |                   |  |
+|                              |   |      | Attribute Type = 1    |  |               |  | Result Code       |  |
+|                              |   |      | Error Code (Optional) |  |               |  | Error Message ... |  |
+| ... Error Message (Optional) |   |      |                       |  |               |  |                   |  |
+
+**Figure 7-13/J.212 – Result code AVP**
+
+This message contains results codes, optional error codes, and optional error messages when tearing down a Control Connection or a Session.
+
+#### 7.5.1.3 Host name (SCCRQ, SCCRP)
+
+![](8c880d6b715587bd710a9ba8414469b1_img.jpg)
+
+|              |   |      |                    |  |               |  |          |  |
+|--------------|---|------|--------------------|--|---------------|--|----------|--|
+| 0            | 7 |      | 15                 |  | 23            |  | 31       |  |
+| M            | H | Resv | Length = 6 + N     |  | Vendor ID = 0 |  |          |  |
+|              |   |      | Attribute Type = 7 |  |               |  | Host ... |  |
+| ... Name ... |   |      |                    |  |               |  |          |  |
+
+**Figure 7-14/J.212 – Host name AVP**
+
+The host name is typically the fully qualified domain name (FQDN) of each device.
+
+#### 7.5.1.4 Vendor name (SCCRQ, SCCRP)
+
+![](f24f909d837b5476783e1bbea2dfc143_img.jpg)
+
+|              |   |      |                    |  |               |  |            |  |
+|--------------|---|------|--------------------|--|---------------|--|------------|--|
+| 0            | 7 |      | 15                 |  | 23            |  | 31         |  |
+| M            | H | Resv | Length = 6 + N     |  | Vendor ID = 0 |  |            |  |
+|              |   |      | Attribute Type = 8 |  |               |  | Vendor ... |  |
+| ... Name ... |   |      |                    |  |               |  |            |  |
+
+**Figure 7-15/J.212 – Vendor name AVP**
+
+The M-CMTS Core SHOULD identify itself with an ASCII Vendor ID string during the SCCRQ message. The EQAM SHOULD identify itself with an ASCII Vendor ID string during the SCCRP message. Note that this is an optional AVP in [RFC-L2TPv3].
+
+#### 7.5.1.5 Serial number (ICRQ, OCRQ)
+
+![](2dfd7b53bd3c518fc1f68921ed2bf441_img.jpg)
+
+|            |   |      |                     |  |               |  |            |  |
+|------------|---|------|---------------------|--|---------------|--|------------|--|
+| 0          | 7 |      | 15                  |  | 23            |  | 31         |  |
+| M          | H | Resv | Length = 10         |  | Vendor ID = 0 |  |            |  |
+|            |   |      | Attribute Type = 15 |  |               |  | Serial ... |  |
+| ... Number |   |      |                     |  |               |  |            |  |
+
+**Figure 7-16/J.212 – Serial number AVP**
+
+This number is assigned by the originator of the message and is similar in concept to a transaction ID. Its main use is to aid in debugging message flows.
+
+#### 7.5.1.6 Router ID (SCCRQ, SCCRP)
+
+| 0                   |   | 7    |  | 15          |            | 23            |  | 31 |  |  |  |  |  |  |  |  |  |
+|---------------------|---|------|--|-------------|------------|---------------|--|----|--|--|--|--|--|--|--|--|--|
+| M                   | H | Resv |  | Length = 10 |            | Vendor ID = 0 |  |    |  |  |  |  |  |  |  |  |  |
+| Attribute Type = 60 |   |      |  |             | Router ... |               |  |    |  |  |  |  |  |  |  |  |  |
+| ... ID              |   |      |  |             |            |               |  |    |  |  |  |  |  |  |  |  |  |
+
+**Figure 7-17/J.212 – Router ID AVP**
+
+The Router ID is typically the IP address of each endpoint.
+
+#### 7.5.1.7 Assigned control connection ID (SCCRQ, SCCRP, StopCCN)
+
+| 0                   |   | 7    |  | 15          |                        | 23            |  | 31 |  |  |  |  |  |  |  |  |  |
+|---------------------|---|------|--|-------------|------------------------|---------------|--|----|--|--|--|--|--|--|--|--|--|
+| M                   | H | Resv |  | Length = 10 |                        | Vendor ID = 0 |  |    |  |  |  |  |  |  |  |  |  |
+| Attribute Type = 61 |   |      |  |             | Control Connection ... |               |  |    |  |  |  |  |  |  |  |  |  |
+| ... ID              |   |      |  |             |                        |               |  |    |  |  |  |  |  |  |  |  |  |
+
+**Figure 7-18/J.212 – Control connection ID AVP**
+
+This is the control connection ID for DEPI. During SCCRQ, the M-CMTS Core uses this AVP to inform the EQAM what value of Control Connection ID to use in the L2TPv3 Control Header for control messages originated by the EQAM. During SCCRP, the EQAM uses this AVP to inform the M-CMTS Core what value of Control Connection ID to use in the L2TPv3 Control header for control messages originated by the M-CMTS Core. Since the M-CMTS Core has not been informed by the EQAM prior to the first SCCRQ message, the M-CMTS core uses a value of 0 for the control connection ID in the L2TPv3 Control Header of the SCCRQ message.
+
+#### 7.5.1.8 Pseudowire capabilities list (SCCRQ, SCCRP)
+
+| 0                   |   | 7    |  | 15              |                   | 23            |  | 31 |  |  |  |  |  |  |  |  |  |
+|---------------------|---|------|--|-----------------|-------------------|---------------|--|----|--|--|--|--|--|--|--|--|--|
+| M                   | H | Resv |  | Length = 6 + 2N |                   | Vendor ID = 0 |  |    |  |  |  |  |  |  |  |  |  |
+| Attribute Type = 62 |   |      |  |                 | Pseudowire Type 0 |               |  |    |  |  |  |  |  |  |  |  |  |
+| Pseudowire Type 1   |   |      |  |                 | Pseudowire Type N |               |  |    |  |  |  |  |  |  |  |  |  |
+
+**Figure 7-19/J.212 – Pseudowire capabilities list AVP**
+
+The Pseudowire Capabilities List indicates the capabilities of the M-CMTS Core and EQAM. There are two PW Types defined for DEPI. See Table 7-4.
+
+**Table 7-4/J.212 – Pseudowire types**
+
+| Pseudowire type                                                                        | Mnemonic | Value   |
+|----------------------------------------------------------------------------------------|----------|---------|
+| MPT Pseudowire                                                                         | MPTPW    | 0x000C* |
+| PSP Pseudowire                                                                         | PSPPW    | 0x000D* |
+| * These are to be considered temporary values, pending official assignments from IANA. |          |         |
+
+The M-CMTS Core MUST indicate its support for PSP and D-MPT mode by including one or both of the DEPI PW Types in the Pseudowire Capabilities List. The EQAM MUST indicate its support for PSP and D-MPT mode by including one or both of the DEPI PW Types in the Pseudowire Capabilities List.
+
+#### 7.5.1.9 Local session ID (ICRQ, ICRP, ICCN, CDN, SLI)
+
+![](bb4d2112ed07e2031c92fbff3494af9f_img.jpg)
+
+|                     |   |      |  |             |                   |               |  |    |  |
+|---------------------|---|------|--|-------------|-------------------|---------------|--|----|--|
+| 0                   |   | 7    |  | 15          |                   | 23            |  | 31 |  |
+| M                   | H | Resv |  | Length = 10 |                   | Vendor ID = 0 |  |    |  |
+| Attribute Type = 63 |   |      |  |             | Local Session ... |               |  |    |  |
+| ... ID              |   |      |  |             |                   |               |  |    |  |
+
+Figure 7-20/J.212 – Local session ID AVP
+
+When a session is established, the M-CMTS Core and EQAM each choose their own Session ID and advertise it to each other with this AVP. This means that a single session setup sets up two unidirectional sessions, one in each direction.
+
+#### 7.5.1.10 Remote session ID (ICRQ, ICRP, ICCN, CDN, SLI)
+
+![](9a14684f8ae1345c6efea6f5994c730c_img.jpg)
+
+|                     |   |      |  |             |                    |               |  |    |  |
+|---------------------|---|------|--|-------------|--------------------|---------------|--|----|--|
+| 0                   |   | 7    |  | 15          |                    | 23            |  | 31 |  |
+| M                   | H | Resv |  | Length = 10 |                    | Vendor ID = 0 |  |    |  |
+| Attribute Type = 64 |   |      |  |             | Remote Session ... |               |  |    |  |
+| ... ID              |   |      |  |             |                    |               |  |    |  |
+
+Figure 7-21/J.212 – Remote session ID AVP
+
+When the M-CMTS Core or EQAM sends a session message to each other, the Remote Session ID is set to the session ID learned previously from the Local Session ID. If the Remote Session ID is not yet known, it is set to 0.
+
+#### 7.5.1.11 Remote end ID (ICRQ)
+
+![](0908107b858fa3783d10d93b3a3444b2_img.jpg)
+
+|                     |   |      |  |            |                  |               |  |    |  |
+|---------------------|---|------|--|------------|------------------|---------------|--|----|--|
+| 0                   |   | 7    |  | 15         |                  | 23            |  | 31 |  |
+| M                   | H | Resv |  | Length = 8 |                  | Vendor ID = 0 |  |    |  |
+| Attribute Type = 66 |   |      |  |            | Remote ID = TSID |               |  |    |  |
+
+Figure 7-22/J.212 – Remote end ID AVP
+
+DEPI uses the TSID from the QAM Channel as the Remote End ID. The TSID is an unsigned two-octet integer and is used to bind a session to a QAM Channel.
+
+#### 7.5.1.12 Pseudowire type (ICRQ)
+
+![](5879500ca01e1a2521654beff6c289a4_img.jpg)
+
+|                     |   |      |  |            |                 |               |  |    |  |
+|---------------------|---|------|--|------------|-----------------|---------------|--|----|--|
+| 0                   |   | 7    |  | 15         |                 | 23            |  | 31 |  |
+| M                   | H | Resv |  | Length = 8 |                 | Vendor ID = 0 |  |    |  |
+| Attribute Type = 68 |   |      |  |            | Pseudowire Type |               |  |    |  |
+
+Figure 7-23/J.212 – Pseudowire type AVP
+
+DEPI uses the Pseudowire Type values defined in 7.5.1.8 to indicate the type of DEPI session requested.
+
+#### 7.5.1.13 L2-specific sublayer (ICRQ, ICRP, ICCN)
+
+![](ad91a8c592581096c346cdd7a2bdf9f1_img.jpg)
+
+|                     |   |      |  |            |                           |               |  |    |  |
+|---------------------|---|------|--|------------|---------------------------|---------------|--|----|--|
+| 0                   |   | 7    |  | 15         |                           | 23            |  | 31 |  |
+| M                   | H | Resv |  | Length = 8 |                           | Vendor ID = 0 |  |    |  |
+| Attribute Type = 69 |   |      |  |            | L2-Specific Sublayer Type |               |  |    |  |
+
+Figure 7-24/J.212 – L2-specific sublayer AVP
+
+The M-CMTS Core MUST include the L2-Specific Sublayer AVP in the ICRQ and ICCN messages, indicating the L2-Specific Sublayer Header Type consistent with the Pseudowire type for the DEPI flow. The EQAM MUST include the L2-Specific Sublayer AVP in the ICRP message, indicating the L2-Specific Sublayer Header Type consistent with the Pseudowire type for the DEPI flow.
+
+**Table 7-5/J.212 – L2-Specific sublayer types**
+
+| L2-specific sublayer type                                                              | Value |
+|----------------------------------------------------------------------------------------|-------|
+| MPT Specific Sublayer                                                                  | 3*    |
+| PSP Specific Sublayer                                                                  | 4*    |
+| * These are to be considered temporary values, pending official assignments from IANA. |       |
+
+#### 7.5.1.14 Data sequencing (ICRP)
+
+![](cf8bd014a50b7c69435e804f67f9617f_img.jpg)
+
+|   |   |                     |            |                           |
+|---|---|---------------------|------------|---------------------------|
+| 0 | 7 | 15                  | 23         | 31                        |
+| M | H | Resv                | Length = 8 | Vendor ID = 0             |
+|   |   | Attribute Type = 70 |            | Data Sequencing Level = 2 |
+
+**Figure 7-25/J.212 – Data sequencing AVP**
+
+The EQAM MUST include the Data Sequencing AVP in the ICRP message, indicating Data Sequencing Level 2 is required (all incoming data packets require sequencing).
+
+#### 7.5.1.15 Circuit status (ICRQ, ICRP, ICCN, SLI)
+
+![](09e20a17ecd8042b3d9b7fd462f2d9b4_img.jpg)
+
+|   |   |                     |            |               |
+|---|---|---------------------|------------|---------------|
+| 0 | 7 | 15                  | 23         | 31            |
+| M | H | Resv                | Length = 8 | Vendor ID = 0 |
+|   |   | Attribute Type = 71 |            | Reserved N A  |
+
+**Figure 7-26/J.212 – Circuit status AVP**
+
+**N** 1 bit – The New bit indicates whether the status indication is for a new DEPI session (1) or an existing DEPI session (0). The New bit SHOULD be set the first time the DEPI session is established after provisioning.
+
+**A** 1 bit – The Active bit indicates whether the DEPI session is up (1) or down (0). Once the M-CMTS Core is aware that the DEPI session is down, the M-CMTS Core MUST NOT attempt to pass data traffic on the DEPI session.
+
+DEPI uses the Circuit Status AVP to indicate whether the DEPI session is up and able to pass data traffic, or down and unable to pass data traffic. The Circuit Status ID does not control the RF output of the QAM Channel. Note that the Circuit Status AVP is sent by both the M-CMTS Core and the EQAM.
+
+### 7.5.2 DEPI specific AVPs
+
+The AVP types defined specifically for DEPI are shown in Table 7-6. The range of Attribute Types from 0-99 is reserved for DEPI Session Specific AVPs. These AVPs are only used in L2TP session messages.
+
+**Table 7-6/J.212 – DEPI defined general session AVPs**
+
+| Attribute type | Description                      |
+|----------------|----------------------------------|
+| 0              | Reserved                         |
+| 1              | DEPI Result Code                 |
+| 2              | DEPI Resource Allocation Request |
+| 3              | DEPI Resource Allocation Reply   |
+| 4              | DEPI Local MTU                   |
+| 5              | DOCSIS SYNC Control              |
+| 6              | EQAM Capability Bits             |
+| 7              | DEPI Remote MTU                  |
+| 8              | DEPI Local UDP Port              |
+
+#### 7.5.2.1 DEPI result and error code (CDN, SLI)
+
+![](8e80de0cac529b2c3775d677c5203133_img.jpg)
+
+|                              |   |      |                |    |                   |                  |  |    |  |
+|------------------------------|---|------|----------------|----|-------------------|------------------|--|----|--|
+| 0                            |   | 7    |                | 15 |                   | 23               |  | 31 |  |
+| M                            | H | Resv | Length = 8 + N |    |                   | Vendor ID = 4491 |  |    |  |
+| Attribute Type = 1           |   |      |                |    | Result Code       |                  |  |    |  |
+| Error Code (Optional)        |   |      |                |    | Error Message ... |                  |  |    |  |
+| ... Error Message (Optional) |   |      |                |    |                   |                  |  |    |  |
+
+**Figure 7-27/J.212 – DEPI result and error code AVP**
+
+The format of the field of this AVP is identical to the field in the standard L2TPv3 result and error code AVP except that the Vendor ID field has the value of 4491 rather than 0. The Result and Error Codes for this AVP are unique to DEPI, and are in addition to the standard Result and Error codes in [RFC-L2TPv3].
+
+The following new Result Codes, Error Codes, and Error Messages are required specifically for use with DEPI:
+
+| Result code | Result description                                                              |
+|-------------|---------------------------------------------------------------------------------|
+| 0           | Session not established – Bad DEPI AVP Reference                                |
+| 1           | Session not established – Bad PHY AVP Request                                   |
+| 2           | Session not established or disconnected for the reason indicated in Error Code. |
+
+| Error code                                                                                                                           | Error description                                            |
+|--------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------|
+| 0                                                                                                                                    | Device is not yet ready or configured properly.              |
+| 1                                                                                                                                    | Attempt to modify a locked PHY Parameter.                    |
+| 2                                                                                                                                    | Attempt to modify PHY Parameter failed – out of range value. |
+| 3                                                                                                                                    | Requested PSP Flow PHBIDs not supported.                     |
+| 4                                                                                                                                    | Incorrect pseudowire type used in session.                   |
+| NOTE – One cause of Error Code 0 would be if the EQAM did not have the values of M and N configured for the QAM Channel Symbol Rate. |                                                              |
+
+#### 7.5.2.2 DEPI resource allocation request (ICRQ)
+
+![](6cc85a2b62fd8a2a3faab29730f20e81_img.jpg)
+
+|                    |   |      |  |                |   |                  |  |    |         |
+|--------------------|---|------|--|----------------|---|------------------|--|----|---------|
+| 0                  |   | 7    |  | 15             |   | 23               |  | 31 |         |
+| M                  | H | Resv |  | Length = 6 + N |   | Vendor ID = 4491 |  |    |         |
+| Attribute Type = 2 |   |      |  | X              | X | PHBID 1          |  | X  | PHBID N |
+
+Figure 7-28/J.212 – DEPI resource allocation request AVP
+
+**M** 1 bit. The Mandatory bit MUST be set to a 1.
+
+**Length** 10 bits. 6 bytes plus one additional byte for each flow that is requested.
+
+**Attribute Type** 2 bytes. Set to 2.
+
+Each flow request entry consists of:
+
+**PHBID** 6 bits. Per Hop Behaviour Identifier being requested by the M-CMTS Core. Per hop behaviours identifiers are defined in 6.2.1.
+
+In the ICRQ message, the M-CMTS Core requests for a number of flows for a session. Each byte in the attribute payload represents a request for one unique flow. Each request contains the PHBID that will be used for that flow. For D-MPT mode operation, the M-CMTS Core MUST request a single flow.
+
+#### 7.5.2.3 DEPI resource allocation reply (ICRP)
+
+![](30a91d1c3ead5af4823f4f3330e4ac1e_img.jpg)
+
+|                    |   |         |  |                    |  |                  |  |                        |  |
+|--------------------|---|---------|--|--------------------|--|------------------|--|------------------------|--|
+| 0                  |   | 7       |  | 15                 |  | 23               |  | 31                     |  |
+| M                  | H | Resv    |  | Length = 8 + 4 * N |  | Vendor ID = 4491 |  |                        |  |
+| Attribute Type = 3 |   |         |  | Reserved           |  |                  |  |                        |  |
+| X                  | X | PHBID 1 |  | Reserved           |  | Flow ID 1        |  | UDP Destination Port 1 |  |
+| X                  | X | PHBID N |  | Reserved           |  | Flow ID N        |  | UDP Destination Port N |  |
+
+Figure 7-29/J.212 – DEPI resource allocation reply AVP
+
+**M** 1 bit. The Mandatory bit MUST be set to a 1.
+
+**Length** 10 bits. 8 bytes plus 4 additional bytes for each flow.
+
+**Attribute Type** 2 bytes. Set to 3.
+
+Each flow response entry consists of:
+
+**PHBID** 6 bits. Per Hop Behaviour Identifier that was requested by the M-CMTS Core. Per hop behaviours identifiers are defined in 6.2.1.
+
+**Flow ID** 3 bits. This is the flow ID assigned by the EQAM. The flow ID is unique within a session.
+
+**UDP Dest Port** 2 bytes. This is the UDP Destination Port as specified by the EQAM that the M-CMTS Core MUST use for the session header if the M-CMTS and EQAM have been configured to use a UDP header with L2TPv3. This value MUST be unique for each session. This value MAY be unique for each flow. If L2TPv3 has been configured to not use UDP headers, then this field MUST be set to all 0's by the EQAM and MUST be ignored by the M-CMTS Core.
+
+In the ICRP message, the EQAM responds by creating flows that match the flows requested. The EQAM specifies the Flow ID and the UDP Destination Port for each flow. The PHBID is unchanged from the flow request field. If the EQAM does not support a PHBID referenced in the request from the M-CMTS Core, the EQAM can signal that by not including the PHBID in this response. If the EQAM
+
+cannot support any of the PHBIDs requested by the M-CMTS Core, then the EQAM MUST tear down the session by issuing a CDN message.
+
+#### 7.5.2.4 DEPI local MTU (ICRQ)
+
+| 0                  |   | 7    |  | 15             |  | 23               |  | 31 |
+|--------------------|---|------|--|----------------|--|------------------|--|----|
+| M                  | H | Resv |  | Length = 8     |  | Vendor ID = 4491 |  |    |
+| Attribute Type = 4 |   |      |  | DEPI Local MTU |  |                  |  |    |
+
+**Figure 7-30/J.212 – DEPI local MTU AVP**
+
+**Length** 10 bits. Set to 8.
+
+**Attribute Type** 2 bytes. Set to 4.
+
+**DEPI Local MTU** 2 bytes. In the ICRQ message, this is the MTU (Maximum Transmission Unit) that the M-CMTS can receive from the EQAM on the CIN interface.
+
+The MTU is Layer 3 payload of a Layer 2 frame. For DEPI, the MTU would include the L2TPv3 header and payload, the UDP header if present, and the IP header, but would not include the Ethernet Header or CRC. For example, a 1518-byte Ethernet frame (1522 bytes if VLAN tags are present) would support an MTU of 1500 bytes.
+
+#### 7.5.2.5 Downstream QAM channel DOCSIS SYNC control (ICRQ, SLI)
+
+| 0                  |   | 7    |  | 15          |                      | 23               |  | 31 |
+|--------------------|---|------|--|-------------|----------------------|------------------|--|----|
+| M                  | H | Resv |  | Length = 14 |                      | Vendor ID = 4491 |  |    |
+| Attribute Type = 5 |   |      |  | E           | DOCSIS SYNC Interval |                  |  |    |
+| MAC SA             |   |      |  |             |                      |                  |  |    |
+| MAC SA             |   |      |  |             |                      |                  |  |    |
+
+**Figure 7-31/J.212 – DOCSIS SYNC AVP**
+
+**Length** 10 bits. Set to 14.
+
+**Attribute Type** 2 bytes. Set to 5.
+
+**E** 1 bit. SYNC Enable. Operation is described below.
+
+**Interval** 15 bits. Nominal interval between SYNC messages in 200 μs steps.
+
+**MAC SA** 48 bits. IEEE 802 MAC address to be used in the source address field.
+
+This AVP is used differently for D-MPT Mode and PSP Mode.
+
+In D-MPT Mode, if E = 0, then the EQAM MUST NOT modify the timestamp values in DOCSIS SYNC messages. If E = 1, then the EQAM MUST find and correct timestamp values in SYNC messages. The DOCSIS SYNC Interval field is set to all zeros by the M-CMTS Core and ignored by the EQAM. The M-CMTS Core SHOULD set the MAC SA field of this AVP to the MAC address of the DOCSIS interface it has associated with the session. The MAC SA field is ignored by the EQAM.
+
+In PSP Mode, if E = 0, then the EQAM MUST NOT transmit a DOCSIS SYNC message. If E = 1, then the EQAM MUST insert and send a DOCSIS SYNC message at a nominal interval specified by the Interval field and with a source MAC address specified by the MAC SA field. The EQAM MUST support DOCSIS SYNC Interval values between 0x000A (2 ms) and 0x03E8 (200 ms). Although the measured time between any two SYNC messages might vary depending on traffic, the measured time MUST be within ±2.5 ms of the nominal value, and MUST NOT exceed the maximum value defined in Annex B. The M-CMTS Core SHOULD set the MAC SA field of this
+
+AVP to the MAC address of the DOCSIS interface it has associated with the session. The EQAM MUST use the address in the MAC SA field as the source address in the MAC management header for all subsequent SYNC messages.
+
+The M-CMTS Core MUST use this AVP to convey the treatment of DOCSIS SYNC messages by the EQAM.
+
+#### 7.5.2.6 EQAM capabilities AVP (ICRQ)
+
+| 0                  |   | 7    |  | 15         |                         | 23               |  | 31 |  |
+|--------------------|---|------|--|------------|-------------------------|------------------|--|----|--|
+| M                  | H | Resv |  | Length = 8 |                         | Vendor ID = 4491 |  |    |  |
+| Attribute Type = 6 |   |      |  |            | EQAM Capabilities Field |                  |  |    |  |
+
+Figure 7-32/J.212 – EQAM capabilities AVP
+
+**Length** 10 bits. Set to 8.
+
+**Attribute Type** 2 bytes. Set to 6.
+
+**Capabilities** 2 bytes. EQAM Capabilities Field. Default value of all bits is 0.
+
+- Bit 0: A "1" indicates that the EQAM supports DLM-EE-RQ and DLM-EE-RP packets. A "0" indicates the EQAM does not support these two DLM packets.
+- Bits 1 through 15: Reserved. Sender must set to 0. Receiver must ignore.
+
+#### 7.5.2.7 DEPI remote MTU (ICRP)
+
+| 0                  |   | 7    |  | 15         |                 | 23               |  | 31 |  |
+|--------------------|---|------|--|------------|-----------------|------------------|--|----|--|
+| M                  | H | Resv |  | Length = 8 |                 | Vendor ID = 4491 |  |    |  |
+| Attribute Type = 7 |   |      |  |            | DEPI Remote MTU |                  |  |    |  |
+
+Figure 7-33/J.212 – DEPI remote MTU Max payload AVP
+
+**Length** 10 bits. Set to 8.
+
+**Attribute Type** 2 bytes. Set to 7.
+
+**DEPI MTU** 2 bytes. In the ICRP message, this is the MTU that the EQAM can receive from the M-CMTS Core on the CIN interface. The MTU is Layer 3 payload of a Layer 2 frame.
+
+#### 7.5.2.8 Local UDP port (ICRQ)
+
+| 0                  |   | 7    |  | 15         |                | 23               |  | 31 |  |
+|--------------------|---|------|--|------------|----------------|------------------|--|----|--|
+| M                  | H | Resv |  | Length = 8 |                | Vendor ID = 4491 |  |    |  |
+| Attribute Type = 8 |   |      |  |            | Local UDP Port |                  |  |    |  |
+
+Figure 7-34/J.212 – Local UDP port AVP
+
+**Length** 10 bits. Set to 8.
+
+**Attribute Type** 2 bytes. Set to 8.
+
+**Connect Speed** 16 bits. UDP port to be used for session packets that are being sent to the local LCP.
+
+The M-CMTS Core would issue this AVP during the session setup if UDP is enabled and if the M-CMTS Core wants a data session to use a different UDP port for sending session packets from
+
+the EQAM to the M-CMTS Core other than the UDP port that was negotiated during the Control Connection setup.
+
+The M-CMTS Core MAY support the Local UDP Port AVP. The EQAM MAY support the Local UDP Port AVP.
+
+### 7.5.3 QAM channel PHY AVPs
+
+The QAM Channel Physical Layer specific AVP types defined for DEPI are shown in Table 7-7. The range of Attribute Types from 100-199 is reserved for QAM Channel PHY AVPs. These AVPs are only used in L2TP session messages.
+
+**Table 7-7/J.212 – DEPI defined QAM channel PHY AVPs**
+
+| Attribute type | Description                              |
+|----------------|------------------------------------------|
+| 100            | Downstream QAM Channel TSID Group        |
+| 101            | Downstream QAM Channel Frequency         |
+| 102            | Downstream QAM Channel Power             |
+| 103            | Downstream QAM Channel Modulation        |
+| 104            | Downstream QAM Channel J.83 Annex        |
+| 105            | Downstream QAM Channel Symbol Rate       |
+| 106            | Downstream QAM Channel Interleaver Depth |
+| 107            | Downstream QAM Channel RF Mute           |
+
+These AVPs define the generic PHY parameters for a QAM Channel. These AVPs are sent from the EQAM to the M-CMTS Core to inform the M-CMTS Core of the EQAM current configuration and which values are allowed to be changed. This AVP is then sent from the M-CMTS Core to the EQAM to configure selected PHY level parameters.
+
+The following fields have a common meaning across this group of AVPs, and are described once here:
+
+**M** 1 bit. The Mandatory bit MUST be set to a 1 for both ICRP and ICCN (if applicable).
+
+**L** 1 bit. Lock bit. This bit allows the EQAM to indicate which elements of the configuration have been locked down in configuration. For ICRP (from EQAM to M-CMTS Core), a value of 0 indicates the parameter described in the Attribute Value field is Read-Only. A value of 1 indicates the parameter is Read/Write. For ICCN (M-CMTS Core to EQAM), this value is set to 0 by the M-CMTS Core and ignored by the EQAM.
+
+**TSID Group ID** 7 bits. If the referenced attribute is common to other QAM Channels, this field is set to a TSID Group as defined by a TSID Group AVP. Otherwise, this field is set to all zeros.
+
+The AVP programming options listed below in this Recommendation may not be available in all EQAM products. To be considered compliant to the DEPI Recommendation, a M-CMTS Core or an EQAM MUST support a particular QAM Channel AVP attribute only if that attribute represents a feature available on that particular platform. For example, if an EQAM does not support Annex C/J.83 as a feature, then it does not have to support the QAM Channel AVP Annex C attribute value.
+
+#### 7.5.3.1 Downstream QAM channel TSID group (ICRP)
+
+![](cc98b584f9b31fe69948e3fa65a3ba69_img.jpg)
+
+|                      |   |      |  |                 |         |                  |  |          |  |
+|----------------------|---|------|--|-----------------|---------|------------------|--|----------|--|
+| 0                    |   | 7    |  | 15              |         | 23               |  | 31       |  |
+| M                    | H | Resv |  | Length = 8 + 2N |         | Vendor ID = 4491 |  |          |  |
+| Attribute Type = 100 |   |      |  |                 | L       | TSID Group ID    |  | Reserved |  |
+| TSID #1              |   |      |  |                 | TSID #2 |                  |  |          |  |
+| TSID #3              |   |      |  |                 | TSID #N |                  |  |          |  |
+
+Figure 7-35/J.212 – TSID group AVP
+
+**Length** 10 bits. Variable. Set to  $(8 + 2 * \text{number of TSID entries})$ .
+
+**Attribute Type** 2 bytes. Set to 100.
+
+**L** 1 bit. Lock bit. Not used. Set to 0.
+
+**TSID Group ID** 7 bits. This is the TSID Group ID that the TSIDs in this list belong to.
+
+**TSID #1-N** 16 bits. List of TSIDs.
+
+Some PHY level attribute types may be common to more than one QAM Channel. As such, changing that attribute on one QAM Channel may change that attribute on other QAM Channels. The EQAM indicates this dependency by defining TSID groups. This AVP MAY be repeated to define more than one TSID Group. Each TSID group is associated with one or more PHY level parameters by including the TSID Group ID within the PHY parameter AVP.
+
+#### 7.5.3.2 Downstream QAM channel frequency (ICRP, ICCN, SLI)
+
+![](042af54276c75e7b7b48a3af1f0a84e5_img.jpg)
+
+|                      |   |      |  |             |   |                  |  |          |  |
+|----------------------|---|------|--|-------------|---|------------------|--|----------|--|
+| 0                    |   | 7    |  | 15          |   | 23               |  | 31       |  |
+| M                    | H | Resv |  | Length = 12 |   | Vendor ID = 4491 |  |          |  |
+| Attribute Type = 101 |   |      |  |             | L | TSID Group ID    |  | Reserved |  |
+| Frequency            |   |      |  |             |   |                  |  |          |  |
+
+Figure 7-36/J.212 – Frequency AVP
+
+**Length** 10 bits. Set to 12.
+
+**Attribute Type** 2 bytes. Set to 101.
+
+**Frequency** 4 bytes. This specifies the downstream frequency of a QAM Channel. This is the centre frequency of the downstream channel in Hz stored as a 32-bit binary number.
+
+#### 7.5.3.3 Downstream QAM channel power (ICRP, ICCN, SLI)
+
+![](8825e92f1c325d7393a17cdcdf31a292_img.jpg)
+
+|                      |   |      |  |             |   |                  |  |          |  |
+|----------------------|---|------|--|-------------|---|------------------|--|----------|--|
+| 0                    |   | 7    |  | 15          |   | 23               |  | 31       |  |
+| M                    | H | Resv |  | Length = 10 |   | Vendor ID = 4491 |  |          |  |
+| Attribute Type = 102 |   |      |  |             | L | TSID Group ID    |  | Reserved |  |
+| Power                |   |      |  |             |   |                  |  |          |  |
+
+Figure 7-37/J.212 – Power AVP
+
+**Length** 10 bits. Set to 10.
+
+**Attribute Type** 2 bytes. Set to 102.
+
+**Power** 2 bytes. TX Power in dBmV (unsigned 16-bit, 0.1 dB unit)
+
+#### 7.5.3.4 Downstream QAM channel modulation (ICRP, ICCN, SLI)
+
+![](3d6f5edac3d5e7113d960c2202f1b0fa_img.jpg)
+
+|                      |   |      |  |            |  |                  |               |    |                 |
+|----------------------|---|------|--|------------|--|------------------|---------------|----|-----------------|
+| 0                    |   | 7    |  | 15         |  | 23               |               | 31 |                 |
+| M                    | H | Resv |  | Length = 8 |  | Vendor ID = 4491 |               |    |                 |
+| Attribute Type = 103 |   |      |  |            |  | L                | TSID Group ID |    | Resv Modulation |
+
+Figure 7-38/J.212 – Modulation AVP
+
+**Length** 10 bits. Set to 8.
+
+**Attribute Type** 2 bytes. Set to 103.
+
+**Modulation** 4 bits. This indicates the modulation type of the downstream QAM Channel. The values of this field are:
+
+0 = 64 QAM
+
+1 = 256 QAM
+
+2-15 = reserved
+
+#### 7.5.3.5 Downstream QAM channel J.83 Annex (ICRP, ICCN, SLI)
+
+![](6584b95e34ea1f0b67144aa841db0863_img.jpg)
+
+|                      |   |      |  |            |  |                  |               |    |                 |
+|----------------------|---|------|--|------------|--|------------------|---------------|----|-----------------|
+| 0                    |   | 7    |  | 15         |  | 23               |               | 31 |                 |
+| M                    | H | Resv |  | Length = 8 |  | Vendor ID = 4491 |               |    |                 |
+| Attribute Type = 104 |   |      |  |            |  | L                | TSID Group ID |    | Resv J.83 Annex |
+
+Figure 7-39/J.212 – J.83 Annex AVP
+
+**Length** 10 bits. Set to 8.
+
+**Attribute Type** 2 bytes. Set to 104.
+
+**J.83** 4 bits. This indicates the Annex of [J.83] to be used on the downstream QAM Channel. The J.83 Annex defines the values of:
+
+- Alpha (which in turn is dependent upon the choice of modulation)
+- Forward Error Correction Frame Sync on/off
+- Forward Error Correction Parity Bytes
+- Trellis Coding enabled/disabled
+
+The values of this field are:
+
+0 = Annex A / DVB EN-300429
+
+1 = Annex B
+
+2 = Annex C
+
+3-15 = reserved
+
+Note that a particular EQAM might only support a subset of the attribute values listed above. For more information, refer to [J.210].
+
+#### 7.5.3.6 Downstream QAM channel symbol rate (ICRP, ICCN, SLI)
+
+![](3c6151f296d5800335472b7dc00ce423_img.jpg)
+
+|                      |   |      |  |                    |   |                  |  |          |  |
+|----------------------|---|------|--|--------------------|---|------------------|--|----------|--|
+| 0                    |   | 7    |  | 15                 |   | 23               |  | 31       |  |
+| M                    | H | Resv |  | Length = 8 + 4 * N |   | Vendor ID = 4491 |  |          |  |
+| Attribute Type = 105 |   |      |  |                    | L | TSID Group ID    |  | Reserved |  |
+| M                    |   |      |  |                    | N |                  |  |          |  |
+| M                    |   |      |  |                    | N |                  |  |          |  |
+
+Figure 7-40/J.212 – Symbol Rate AVP
+
+- Length** 10 bits. Set to 8 plus 4 times the number of M/N pairs.
+- Attribute Type** 2 bytes. Set to 105.
+- M** 2 bytes. Numerator of frequency to symbol coefficient.
+- N** 2 bytes. Denominator of frequency to symbol coefficient.
+
+The downstream symbol rate is set by choosing the appropriate values for M and N such that:
+
+$$\text{Symbol Rate (Msymbol/s)} = f * M/N$$
+
+where f denotes the system master clock frequency.
+
+In the ICRP message, the EQAM MUST list all the M and N value pairs that it has been configured to support. The EQAM MAY include a M/N pair, each with a value of 0xFFFF, to indicate that the EQAM has a variable symbol rate capability. In that case, the M-CMTS Core can request a value of M and N that the M-CMTS Core has been configured to use. Note that the lock bit is asserted when the M/N values are pre-configured, and de-asserted when a variable symbol rate capability is indicated.
+
+If the EQAM has not been configured with M and N values and does not support a variable symbol rate option, then the EQAM MUST reject the session setup, and return the appropriate error code.
+
+In the ICCN message, the M-CMTS Core MUST select one of those M and N pairs to indicate to the EQAM what symbol rate to use. The M-CMTS Core will subsequently use the values of M and N in the UCD MAC management message.
+
+It should be noted that in operational scenarios where multiple downstreams may be used as sources of synchronization for CMs that drive a common upstream, those multiple downstreams will have to provide the same M/N values since the single M-CMTS Core upstream receiver can only operate with one M/N value.
+
+#### 7.5.3.7 Downstream QAM channel interleaver depth (ICRP, ICCN, SLI)
+
+![](2c38051409fe1c92ed774b445a768886_img.jpg)
+
+|                      |   |      |  |             |   |                  |  |          |  |
+|----------------------|---|------|--|-------------|---|------------------|--|----------|--|
+| 0                    |   | 7    |  | 15          |   | 23               |  | 31       |  |
+| M                    | H | Resv |  | Length = 10 |   | Vendor ID = 4491 |  |          |  |
+| Attribute Type = 106 |   |      |  |             | L | TSID Group ID    |  | Reserved |  |
+| I                    |   | J    |  |             |   |                  |  |          |  |
+
+Figure 7-41/J.212 – Interleaver depth AVP
+
+- Length** 10 bits. Set to 10.
+- Attribute Type** 2 bytes. Set to 106.
+- I** 1 byte. This indicates the I value of the interleaver depth of the downstream QAM Channel.
+- J** 1 byte. This indicates the J value of the interleaver depth of the downstream QAM Channel.
+
+#### 7.5.3.8 Downstream QAM Channel RF mute (ICRP, ICCN)
+
+![](fc02903382cebe6fc11e4c0d74b5313f_img.jpg)
+
+|                      |   |      |  |            |   |                  |  |               |  |
+|----------------------|---|------|--|------------|---|------------------|--|---------------|--|
+| 0                    |   | 7    |  | 15         |   | 23               |  | 31            |  |
+| M                    | H | Resv |  | Length = 8 |   | Vendor ID = 4491 |  |               |  |
+| Attribute Type = 107 |   |      |  |            | L | TSID Group ID    |  | QAM Ch Status |  |
+
+Figure 7-42/J.212 – RF mute AVP
+
+**Length** 10 bits. Set to 8.
+
+**Attribute Type** 2 bytes. Set to 107.
+
+**QAM Ch Status** 1 byte. Bit 0 = 0 to unmute the RF output of the QAM Channel. Bit 0 = 1 to mute the RF output of the QAM Channel. Bits 7-1 are reserved. They should be set to 0 when transmitted and ignored when received.
+
+# 8 DEPI forwarding plane
+
+NOTE – This clause is normative.
+
+The DEPI protocol uses the L2TPv3 protocol over IP either with or without a UDP header. The choice of whether to use a UDP header is based upon system configuration and is the same choice for both the control messages and data messages.
+
+Within the L2TPv3 payload, there are two types of payloads used for DEPI. The first is a MPEG Transport Stream (D-MPT) based format and the second is a Packet Streaming Protocol (PSP) based format. The choice of which format to use is based upon the type of traffic being carried and the capabilities negotiated between the M-CMTS Core and the EQAM.
+
+## 8.1 L2TPv3 transport packet format
+
+This clause describes the various fields of the L2TPv3 packet as it applies to DEPI. The outer encapsulation of the L2TPv3 datagram is shown with a UDP header in Figure 8-1 and without a UDP header in Figure 8-2.
+
+### 8.1.1 Data message with a UDP header
+
+![Diagram of L2TPv3 data packet outer encapsulation with UDP. It shows the structure of the packet from byte 0 to 31, including Ethernet 802.3 Header, Ethernet 802.1Q Optional Header, IPv4 Header, UDP Header, L2TPv3 Data Header, L2TPv3 Sublayer Header, DEPI Payload, and CRC.](b898dcb574f08ea237dd3326abecd185_img.jpg)
+
+The diagram illustrates the structure of an L2TPv3 data packet with outer encapsulation using UDP. The packet is shown in bytes, with markers at 0, 7, 15, 23, and 31.
+
+- Ethernet 802.3 Header (14 bytes):** Contains DA (Destination Address), SA (Source Address), and Length/Type fields.
+- Ethernet 802.1Q Optional Header (4 bytes):** Contains User Priority, C (Canonical), FI (Format Indicator), VLAN Identifier, and MAC Client Length/Type fields.
+- IPv4 Header (20 bytes):** Contains Version, IHL, DS Field, ECN, Total Length, Identification, Flags, Fragment Offset, Time to Live, Protocol, Header Checksum, Source IP Address, and Destination IP Address fields.
+- UDP Header (8 bytes):** Contains Source Port, Destination Port, Length, and Checksum fields.
+- L2TPv3 Data Header (8 bytes):** Contains a 16-bit control field (T, X, X, X, X, X, X, X, X, X, X, X, Ver, Reserved) and Session ID.
+- L2TPv3 Sublayer Header (x bytes):** A variable-length header.
+- DEPI Payload (x bytes):** The variable-length payload.
+- CRC (4 bytes):** The final 4-byte cyclic redundancy check field.
+
+J.212(06)\_F8-1
+
+Diagram of L2TPv3 data packet outer encapsulation with UDP. It shows the structure of the packet from byte 0 to 31, including Ethernet 802.3 Header, Ethernet 802.1Q Optional Header, IPv4 Header, UDP Header, L2TPv3 Data Header, L2TPv3 Sublayer Header, DEPI Payload, and CRC.
+
+Figure 8-1/J.212 – L2TPv3 data packet outer encapsulation with UDP
+
+### 8.1.2 Data message without a UDP header
+
+![Diagram of L2TPv3 data packet outer encapsulation without UDP. The diagram shows a stack of headers: Ethernet 802.3 Header (14 bytes), Ethernet 802.1Q Optional Header (4 bytes), IPv4 Header (20 bytes), L2TPv3 Data Header (4 bytes), L2TPv3 Sublayer Header (x bytes), DEPI Payload (x bytes), and CRC (4 bytes). Bit positions 0, 7, 15, 23, and 31 are marked at the top. The IPv4 header details include Version, IHL, DS Field, ECN, Total Length, Identification, Flags, Fragment Offset, Time to Live, Protocol (115), Header Checksum, Source IP Address, and Destination IP Address. The L2TPv3 Data Header includes Session ID. The L2TPv3 Sublayer Header is a single field. The DEPI Payload is the main data section. The CRC is the final 4-byte field.](284768c5ee1a05aa1b9ce396f606a040_img.jpg)
+
+J.212(06)\_F8-2
+
+Diagram of L2TPv3 data packet outer encapsulation without UDP. The diagram shows a stack of headers: Ethernet 802.3 Header (14 bytes), Ethernet 802.1Q Optional Header (4 bytes), IPv4 Header (20 bytes), L2TPv3 Data Header (4 bytes), L2TPv3 Sublayer Header (x bytes), DEPI Payload (x bytes), and CRC (4 bytes). Bit positions 0, 7, 15, 23, and 31 are marked at the top. The IPv4 header details include Version, IHL, DS Field, ECN, Total Length, Identification, Flags, Fragment Offset, Time to Live, Protocol (115), Header Checksum, Source IP Address, and Destination IP Address. The L2TPv3 Data Header includes Session ID. The L2TPv3 Sublayer Header is a single field. The DEPI Payload is the main data section. The CRC is the final 4-byte field.
+
+Figure 8-2/J.212 – L2TPv3 data packet outer encapsulation without UDP
+
+### 8.1.3 Specific headers for data messages
+
+#### 8.1.3.1 L2TPv3 data header
+
+The L2TPv3 fields as defined by [RFC-L2TPv3] are used as follows:
+
+- T** Transport bit. 1 bit. Set to 0 to indicate that this is a data message.
+- X** Reserved bits. 11 bits. Set to 0 by M-CMTS Core; ignored by EQAM.
+- Version** Version Field. 4 bits. Set to 3.
+- Reservation** Reserved field. 16 bits. Not used. Set to 0 by M-CMTS Core; ignored by EQAM.
+- Session ID** Session Identifier. 32 bits. This value is negotiated by the L2TPv3 control plane.
+
+The L2TPv3 cookie field is not required to be supported in DEPI.
+
+The M-CMTS Core MUST support the L2TPv3 data header. The EQAM MUST support the L2TPv3 data header.
+
+#### 8.1.3.2 L2TPv3 DEPI sublayer header
+
+DEPI supports two pseudowire types. The first type, known as D-MPT, is used for transporting MPEG packets. The second type, known as PSP, is used for transporting DOCSIS frames. Each pseudowire type has a unique L2TPv3 DEPI sublayer header format. The fields of these sublayer headers are defined in 8.2 and 8.3. Additionally, both pseudowire types support a latency measurement sublayer header, the fields of which are defined in 8.4.
+
+The M-CMTS Core MUST use the appropriate DEPI Sublayer header for the pseudowire type of the DEPI session.
+
+The EQAM MUST accept packets from the M-CMTS Core that contain the appropriate DEPI sublayer header for the negotiated pseudowire type. The EQAM MUST send a CDN message to tear down a session in which packets are received with the wrong pseudowire type. The EQAM MUST ignore packets received that do not comply with these L2TPv3 DEPI sublayer header definitions.
+
+#### 8.1.3.3 DEPI payload
+
+The payload contains one or more segments. In D-MPT mode, each segment is a 188-byte MPEG packet. In PSP mode, a segment contains either a full DOCSIS frame or a partial DOCSIS frame.
+
+## 8.2 DOCSIS MPT mode
+
+![](0997dbaa9dfecedd60029d70b53327b8_img.jpg)
+
+**DEPI MPT**
+
+|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |        |          |            |   |          |    |                 |    |    |        |        |          |            |   |          |  |                 |  |                |                 |   |                |                 |                                                                                                                                                                                                                                                                                                      |
+|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|----------|------------|---|----------|----|-----------------|----|----|--------|--------|----------|------------|---|----------|--|-----------------|--|----------------|-----------------|---|----------------|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| <table border="1" style="width: 100%; text-align: center; border-collapse: collapse;"> <tr> <td colspan="5" style="border: none; text-align: left;">0</td> <td style="border: none; text-align: center;">7</td> <td style="border: none; text-align: center;">15</td> <td style="border: none; text-align: center;">23</td> <td style="border: none; text-align: right;">31</td> </tr> <tr> <td style="width: 4%;">V<br/>0</td> <td style="width: 4%;">S<br/>1</td> <td style="width: 8%;">H<br/>0 0</td> <td style="width: 12%;">Flow<br/>ID</td> <td style="width: 4%;">X</td> <td colspan="2" style="width: 34%;">Reserved</td> <td colspan="2" style="width: 34%;">Sequence Number</td> </tr> </table> <table border="1" style="width: 100%; text-align: center; border-collapse: collapse; margin-top: 5px;"> <tr><td>MPEG-TS Header</td></tr> <tr><td>MPEG-TS Payload</td></tr> <tr><td style="border: none;">⋮</td></tr> <tr><td>MPEG-TS Header</td></tr> <tr><td>MPEG-TS Payload</td></tr> </table> | 0      |          |            |   |          | 7  | 15              | 23 | 31 | V<br>0 | S<br>1 | H<br>0 0 | Flow<br>ID | X | Reserved |  | Sequence Number |  | MPEG-TS Header | MPEG-TS Payload | ⋮ | MPEG-TS Header | MPEG-TS Payload | <div style="border-left: 1px solid black; padding-left: 5px;">         L2TPv3<br/>DEPI MPT<br/>Sublayer<br/>Header<br/>(4 bytes)       </div><br><br><div style="border-left: 1px solid black; padding-left: 5px;">         1 to N<br/>MPEG-TS<br/>Packets<br/>(188 to<br/>N*188 bytes)       </div> |
+| 0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |        |          |            |   | 7        | 15 | 23              | 31 |    |        |        |          |            |   |          |  |                 |  |                |                 |   |                |                 |                                                                                                                                                                                                                                                                                                      |
+| V<br>0                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      | S<br>1 | H<br>0 0 | Flow<br>ID | X | Reserved |    | Sequence Number |    |    |        |        |          |            |   |          |  |                 |  |                |                 |   |                |                 |                                                                                                                                                                                                                                                                                                      |
+| MPEG-TS Header                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |        |          |            |   |          |    |                 |    |    |        |        |          |            |   |          |  |                 |  |                |                 |   |                |                 |                                                                                                                                                                                                                                                                                                      |
+| MPEG-TS Payload                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |        |          |            |   |          |    |                 |    |    |        |        |          |            |   |          |  |                 |  |                |                 |   |                |                 |                                                                                                                                                                                                                                                                                                      |
+| ⋮                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |        |          |            |   |          |    |                 |    |    |        |        |          |            |   |          |  |                 |  |                |                 |   |                |                 |                                                                                                                                                                                                                                                                                                      |
+| MPEG-TS Header                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |        |          |            |   |          |    |                 |    |    |        |        |          |            |   |          |  |                 |  |                |                 |   |                |                 |                                                                                                                                                                                                                                                                                                      |
+| MPEG-TS Payload                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |        |          |            |   |          |    |                 |    |    |        |        |          |            |   |          |  |                 |  |                |                 |   |                |                 |                                                                                                                                                                                                                                                                                                      |
+
+J.212(06)\_F8-3
+
+**Figure 8-3/J.212 – DOCSIS MPT sublayer header and payload**
+
+- V** 1 bit. VCCV bit. Set to 0. Reserved for compatibility with [VCCV].
+- S** 1 bit. Sequence bit. Set to 1 to indicate that the sequence number field is valid. Set to 0 to indicate that the sequence number field is not valid.
+- H** 2 bits. Extended Header bits. Set to '00' to indicate no extended header.
+- X** 1 bit. Reserved bit. Set to all zeros at the transmitter, ignored at the receiver.
+- Flow ID** 3 bits. Flow Identifier.
+- Reserved** 1 byte. Reserved field. Set to all zeros at the transmitter, ignored at the receiver.
+
+**Seq Num** 2 bytes. Sequence Number. The sequence number increments by one for each data packet sent, and may be used by the receiver to detect packet loss. The initial value of the sequence number SHOULD be random (unpredictable).
+
+The M-CMTS Core MUST NOT put stuffing bytes between the UDP header and the first MPEG-TS header or between consecutive MPEG-TS packets. The M-CMTS Core MUST support all bits in the MPT sublayer header.
+
+The EQAM MUST accept one to seven MPEG-TS packets in a L2TPv3 payload when the path MTU is 1500 bytes in length. The length of an Ethernet frame containing seven MPEG-TS packets with L2TPv3 with a D-MPT L2TPv3 sublayer, UDP, IPv4, 802.1Q headers is 1378 bytes. If the EQAM, the M-CMTS Core, and the network between them all allow larger MTU sizes, the M-CMTS Core MAY increase the total number of MPEG-TS packets transmitted per L2TP packet.
+
+The M-CMTS Core MAY insert null MPEG packets into the D-MPT stream. A null MPEG packet is 188 bytes in length with a reserved PID value of 0x1FFF as defined in [H.222.0]. The EQAM MAY discard these null MPEG packets. The EQAM is only required to support one flow for MPT mode.
+
+## 8.3 PSP mode
+
+![Diagram of DEPI PSP sublayer header and payload structure. The header consists of a 4-byte base header followed by a variable-length segment table. The base header includes fields for V, S, H, Flow ID, X, Segment Count, and Sequence Number. The segment table contains entries with B, E, and Segment Length fields. The payload follows the header and contains multiple segments (Segment X, Segment X+1, ..., Segment X+Y).](c419b566d720267c499087add1506018_img.jpg)
+
+|        |        |                |            |   |   |               |   |                 |  |    |                                                                             |
+|--------|--------|----------------|------------|---|---|---------------|---|-----------------|--|----|-----------------------------------------------------------------------------|
+| 0      |        | 7              |            |   |   | 15            |   | 23              |  | 31 | L2TPv3<br>DEPI PSP<br>Sublayer<br>Header<br>(4 + 2* segment<br>count) bytes |
+| V<br>0 | S<br>1 | H<br>0 0       | Flow<br>ID | X | X | Segment Count |   | Sequence Number |  |    |                                                                             |
+| B      | E      | Segment Length |            |   |   | B             | E | Segment Length  |  |    |                                                                             |
+| B      | E      | Segment Length |            |   |   |               |   |                 |  |    |                                                                             |
+
+Segment X
+
+Segment X+1
+
+Segment X+Y
+
+DEPI  
+PSP  
+Payload  
+(M bytes)
+
+J.212(06)\_F8-4
+
+Diagram of DEPI PSP sublayer header and payload structure. The header consists of a 4-byte base header followed by a variable-length segment table. The base header includes fields for V, S, H, Flow ID, X, Segment Count, and Sequence Number. The segment table contains entries with B, E, and Segment Length fields. The payload follows the header and contains multiple segments (Segment X, Segment X+1, ..., Segment X+Y).
+
+**Figure 8-4/J.212 – DEPI PSP sublayer header and payload**
+
+- V** 1 bit. VCCV bit. Set to 0. Reserved for compatibility with [VCCV].
+- S** 1 bit. Sequence bit. Set to 1 to indicate that the sequence number field is valid. Set to 0 to indicate that the sequence number field is not valid.
+- H** 2 bits. Extended Header bits. Set to '00' to indicate no extended header.
+- X** 1 bit. Reserved bit. Set to all zeros at the transmitter, ignored at the receiver.
+- Flow ID** 3 bits. Flow Identifier.
+- Segment Count** 7 bits. This is the number of segments in the DEPI PSP Payload, and this is also the number of 2 byte entries in the PSP Segment Table.
+- Seq Num** 2 bytes. Sequence Number. The sequence number increments by one for each data packet sent, and may be used by the receiver to detect packet loss. The initial value of the sequence number SHOULD be random (unpredictable).
+
+- B** Begin bit. 1 bit. Set to a 1 to indicate that the PSP Frame contains the beginning of a DOCSIS frame. Otherwise, set to 0.
+- E** End bit. 1 bit. Set to a 1 to indicate that the PSP Frame contains the end of a DOCSIS frame. Otherwise, set to 0.
+
+**Segment Length** 14 bits. Length of DEPI segment in bytes.
+
+The Packet Streaming Protocol can take a series of DOCSIS frames, assemble them into a stream of back to back DOCSIS frames, and then split that stream up into PSP PDUs. In doing so, the first and last DOCSIS frame of a PSP PDU may be split into segments across PSP PDUs. DOCSIS frames which are not the first or last frame in a PSP PDU will not be split. A DOCSIS frame may be split into more than two segments and therefore may be spread across more than two PSP PDUs.
+
+The Segment Table provides information on the contents in each of the subsequent PSP frames. This includes signifying if the frame is the beginning, middle, end, or an entire DOCSIS frame.
+
+## 8.4 DEPI latency measurement (DLM) sublayer header
+
+The DEPI Latency Measurement (DLM) Sublayer Header is used by the M-CMTS Core and the EQAM to measure the delay and latency of the CIN. This measurement is important as the transition network has the potential to affect the latency budgets already established in [J.122] for legacy DOCSIS 1.x and 2.0 devices. To perform this measurement, a packet is sent using the DEPI Latency Measurement Sublayer Header (shown in Figure 8-5) to which the receiver responds. This sublayer header is designed to be used within any active L2TPv3 session between the M-CMTS and the EQAM. It may be used with both MPT and PSP Pseudowire types. It is anticipated that this particular message exchange may occur between hardware mechanisms at either end of the DEPI interface.
+
+![Figure 8-5/J.212 – DLM sublayer header diagram showing a 32-bit header structure with fields for L2TPv3, DEPI Latency Measurement Sublayer Header, and DOCSIS Timestamps.](237b76118be454462fc9b4e96adaa6c7_img.jpg)
+
+|                        |         |    |          |            |                |
+|------------------------|---------|----|----------|------------|----------------|
+| 0                      | 7       | 15 | 23       | 31         |                |
+| V S H                  | Flow ID | X  | Reserved | Code Field | Transaction ID |
+| DOCSIS Timestamp Start |         |    |          |            |                |
+| DOCSIS Timestamp End   |         |    |          |            |                |
+
+Legend: V (1 bit), S (1 bit), H (2 bits), Flow ID (3 bits), X (1 bit), Reserved (1 byte), Code Field (1 byte), Transaction ID (4 bytes). The first 16 bits (V S H Flow ID X Reserved) are part of the L2TPv3 header. The remaining 16 bits (Code Field Transaction ID) are part of the DEPI Latency Measurement Sublayer Header (12 bytes). The DOCSIS Timestamp Start and DOCSIS Timestamp End are 8 bytes each.
+
+Figure 8-5/J.212 – DLM sublayer header diagram showing a 32-bit header structure with fields for L2TPv3, DEPI Latency Measurement Sublayer Header, and DOCSIS Timestamps.
+
+Figure 8-5/J.212 – DLM sublayer header
+
+- V** 1 bit. VCCV bit. Set to 0. Reserved for compatibility with [VCCV].
+- S** 1 bit. Sequence bit. Set to 0.
+- H** 2 bits. Extended Header bits. Set to '01' to indicate the presence of the latency measurement extended header.
+- X** 1 bit. Reserved bit. Set to all zeros at the transmitter, ignored at the receiver.
+- Flow ID** 3 bits. Flow Identifier.
+- Reserved** 1 byte. Reserved field. Set to all zeros at the transmitter, ignored at the receiver.
+- Code Field** 1 byte. The permitted values are described below:
+  - A value of 0 indicates a DLM-EI-RQ (DLM EQAM Ingress Request) packet originated by the M-CMTS Core requesting a measurement to be made at reference point adjacent to the DEPI ingress port of the EQAM.
+  - A value of 1 indicates a DLM-EI-RP (DLM EQAM Ingress Reply) packet originated by the EQAM with a Timestamp End value calculated at reference point adjacent to the DEPI ingress port of the EQAM.
+
+- A value of 2 indicates a DLM-EE-RQ (DLM EQAM Egress Request) packet originated by the M-CMTS core requesting a measurement to be made at reference point adjacent to the DEPI egress port of the EQAM.
+- A value of 3 indicates a DLM-EE-RP (DLM EQAM Egress Reply) packet originated by the EQAM with a Timestamp End value calculated at reference point adjacent to the DEPI egress port of the EQAM.
+- The values of 4 through 255 are reserved.
+
+**Transaction ID** 1 byte. This is a unique ID assigned by the sender and returned by receiver. The transaction ID is unique per session.
+
+**Timestamp Start** 4 bytes. Timestamp sent by sender.
+
+**Timestamp End** 4 bytes. Timestamp existing at the receiver.
+
+The M-CMTS Core MUST support the sending of a DLM-EI-RQ packet and the receiving of a DLM-EI-RP packet. The M-CMTS Core MAY support the sending of a DLM-EE-RQ packet and the receiving of a DLM-EE-RP packet. The CMTS Core (Sender) MUST send the DLM packet to the EQAM on an existing DEPI Session flow (either PSP or MPT). The M-CMTS Core MUST set the proper DSCP values for the DLM packet based on the DEPI Session being measured. The M-CMTS Core MUST provide a configuration mechanism to set the sampling interval through the M-CMTS Core MIB.
+
+The M-CMTS Core MUST report delta measurements that exceed a configured threshold through the M-CMTS Core MIB. The M-CMTS Core MUST NOT send a DLM-EI-RQ or DLM-EE-RQ packet to a particular DEPI session, if there is already a DLM-EI-RQ or DLM-EE-RQ outstanding for that session, or if a DOCSIS frame on that flow has been segmented and the complete DOCSIS frame has not been sent. The M-CMTS Core MUST place the current DOCSIS 32-bit timestamp value in the Timestamp Start field of the message. The M-CMTS Core SHOULD use a timestamp value that is accurate to within a 100 µs of the current timestamp as derived from DTI.
+
+The EQAM MUST support the receiving of a DLM-EI-RQ packet and the sending of a DLM-EI-RP packet. The EQAM MAY support the receiving of a DLM-EE-RQ packet and the sending of a DLM-EE-RP packet. The EQAM MUST support the use of the DLM packet within any active DEPI session. The EQAM is not required to support more than one concurrent latency measurement per session. The EQAM MUST ensure that timestamp value inserted in the Timestamp End field is accurate to within 100 µs of the current timestamp used for SYNC insertion/correction.
+
+For DLM-EI-RQ packets, the EQAM MUST perform the Timestamp insertion prior to queuing the DEPI frame on the MPT or PSP QoS queues. For DLM-EE-RQ packets, if supported, the EQAM MUST perform the Timestamp insertion at the point where the SYNC message is originated. This is outlined in Figure 6-1. The EQAM MUST send the completed Latency Measurement Packet back to the M-CMTS Core that originated the measurement request, and do so with the EQAM DLM Timer value specified in Annex B.
+
+An EQAM that does not support a DLM-EE-RQ packet MUST silently discard the DLM packet without generating a response packet.
+
+## 8.5 M-CMTS core output rate
+
+It is possible that if the M-CMTS Core was to send at data rate which exactly equalled the payload rate of the downstream QAM, and those packets were subject to jitter, that the EQAM would insert an MPEG-TS Null. Once the packets from the M-CMTS Core arrived, there would be an output queue delay that would equal the worst case jitter present at the DEPI input of the EQAM. That queuing delay would not be removed until the input to the EQAM was interrupted and the internal
+
+queue was drained. Further, the rate at which this delay is removed is related to the amount of jitter the input stream has, the peak input rate, and the maximum burst size of the input stream.
+
+The M-CMTS Core MUST be able to rate limit the aggregate of all DEPI sessions, including any null MPEG packets that the M-CMTS Core may have inserted, that are destined to the same QAM Channel within an EQAM. The peak rate of this aggregate MUST be configurable to be a percentage of the QAM Channel payload. The burst size of this aggregate MUST be configurable. The default burst size of the aggregate MUST be the equivalent of three frames per DEPI session. (For a frame size of 1522 bytes, this would be 4566 bytes.)
+
+# Annex A
+
+## DEPI MTU
+
+## A.1 L2TPv3 lower layer payload size
+
+Typically an interface calculates its default maximum payload size by asking the interface below it in the interface column what its maximum payload size and considering its own encapsulation. For example, by default, Ethernet has a frame size of 1518 (without VLANs). The Ethernet encapsulation is 18 bytes, leaving 1500 bytes of payload (MTU) to its upper layer. IP then subtracts the IP header size (typically 20 bytes) to arrive at 1480 bytes available to its upper layer. UDP must then subtract the UDP header size of 8 bytes, arriving at a payload of 1472 bytes. L2TPv3 must subtract the L2TPv3 Data Header size in bytes (8) and calculate its payload as the remainder (typically 1464). This remainder is the defined maximum payload size for an L2TPv3 session that would exist over Ethernet/IP/UDP.
+
+## A.2 Maximum frame size for DEPI
+
+This annex documents the maximum frame size of DEPI when a PSP Pseudowire is used without fragmenting or concatenation.
+
+Table A.1/J.212 – MTU of DEPI
+
+| Field                                                                                                                                                                                                           |                 |                 | Size            |  |  |  |
+|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|-----------------|-----------------|--|--|--|
+| DEPI frame                                                                                                                                                                                                      | Ethernet Header |                 | 14 bytes        |  |  |  |
+|                                                                                                                                                                                                                 | 802.1Q Header   |                 | 4 bytes         |  |  |  |
+|                                                                                                                                                                                                                 | DEPI MTU        | IPv4 Header*    | 20 bytes        |  |  |  |
+|                                                                                                                                                                                                                 |                 | UDP Header      | 8 bytes         |  |  |  |
+|                                                                                                                                                                                                                 |                 | L2TPv3 Header   | 8 bytes         |  |  |  |
+|                                                                                                                                                                                                                 |                 | DEPI-PSP Header | 6 bytes         |  |  |  |
+|                                                                                                                                                                                                                 |                 | DOCSIS frame    | DOCSIS Header   |  |  |  |
+|                                                                                                                                                                                                                 |                 |                 | 6-246 bytes     |  |  |  |
+|                                                                                                                                                                                                                 |                 |                 | Ethernet Header |  |  |  |
+|                                                                                                                                                                                                                 |                 |                 | 14 bytes        |  |  |  |
+|                                                                                                                                                                                                                 |                 |                 | 802.1Q Header   |  |  |  |
+|                                                                                                                                                                                                                 |                 |                 | 4 bytes         |  |  |  |
+|                                                                                                                                                                                                                 |                 |                 | Ethernet PDU    |  |  |  |
+|                                                                                                                                                                                                                 |                 |                 | 1500 bytes      |  |  |  |
+|                                                                                                                                                                                                                 |                 |                 | Ethernet CRC    |  |  |  |
+|                                                                                                                                                                                                                 |                 |                 | 4 bytes         |  |  |  |
+|                                                                                                                                                                                                                 | Ethernet CRC    |                 | 4 bytes         |  |  |  |
+| Total                                                                                                                                                                                                           |                 |                 | 1592-1832 bytes |  |  |  |
+| * Currently, this Recommendation only requires support for IPv4. If IPv6 were to be used for transport, then value should be increased by an additional 20 bytes plus the length of any IPv6 Extension Headers. |                 |                 |                 |  |  |  |
+
+## A.3 Path MTU discovery
+
+Path MTU Discovery relies on the fact that the network elements between the M-CMTS Core and the EQAM all support this protocol [RFC-MTU]. If these network elements do not support Path MTU Discovery, then this mechanism cannot be used and the static configuration option should be used instead.
+
+Path MTU Discovery works when the path between the M-CMTS Core and the EQAM is less than the total frame size generated when using the payload size negotiated during L2TPv3 session establishment. In this circumstance, when the M-CMTS Core sends packets larger than the network can support, then network elements between the M-CMTS Core and the EQAM will generate an ICMP Destination Unreachable message with the code "fragmentation needed and DF set", as per [RFC-IP], toward the source of the tunnelled packet. This error message includes the IP header and UDP header. The M-CMTS Core and the EQAM should have a way to map a UDP port to an L2TP Session ID. The M-CMTS Core and EQAM should reduce the Max Payload of the session referenced in the ICMP Destination Unreachable message to the size requested in the Next-Hop MTU field of the message. The M-CMTS Core and EQAM may periodically attempt to increase the Max Payload of the session to its negotiated maximum and restart this process in case the path through the network has changed and large MTUs are allowed. This technique is described in [RFC-MTU]. The Max Payload size learned through this process will never be greater than the negotiated maximum learned during session establishment.
+
+# Annex B
+
+## Parameters and constants
+
+Table B.1/J.212 – Parameters and constants
+
+| System            | Name                        | Time reference                                           | Minimum value | Default value | Maximum value                                                                                                     |
+|-------------------|-----------------------------|----------------------------------------------------------|---------------|---------------|-------------------------------------------------------------------------------------------------------------------|
+| M-CMTS Core, EQAM | SYNC Interval               | Nominal time between transmission of SYNC messages       |               |               | 200 ms                                                                                                            |
+| M-CMTS Core, EQAM | HELLO Timer                 | L2TPv3 section 4.4                                       |               | 60 s          |                                                                                                                   |
+| M-CMTS Core, EQAM | Control Message Timeout     | L2TPv3 section 4.2                                       |               |               | First attempt: 1 s,<br>then second attempt 2 s,<br>then third attempt: 4 s,<br>then each additional attempt: 8 s. |
+| M-CMTS Core, EQAM | Control Message Retry Count | L2TPv3 section 4.2                                       |               |               | 10                                                                                                                |
+| M-CMTS Core, EQAM | StopCCN Timeout             | L2TPv3 section 3.3.2                                     | 31 s          |               |                                                                                                                   |
+| EQAM              | EQAM DLM Timer              | Time between receipt and retransmission of a DLM packet. |               |               | 100 ms                                                                                                            |
+
+# Appendix I
+
+## DEPI and DOCSIS system performance
+
+## I.1 Introduction
+
+The M-CMTS architecture provides interoperability among different types of equipment performing various sub-functions of a complete CMTS. In previous architectures, all these functions were contained in a single physical card or chassis, so that the delays in communication between sub-functions were effectively zero. M-CMTS introduces non-zero delays between sub-functions. In some instances these delays may impact system performance. Specifically, interposing a CIN between the M-CMTS Core and the EQAM increases the *round-trip time* of the DOCSIS system.
+
+### I.2 Round-trip time and performance
+
+Broadly speaking, round-trip time is the time from a CM's request to the time the CM transmits the data corresponding to that request. The quicker all this happens, the sooner the CM can transmit another request (e.g., a piggyback request), thereby transmitting more data, etc.
+
+Round-trip time limits the performance of a single modem by limiting the number of grants the modem can receive in a given time. For instance, if the system round-trip time is 10 ms, it is not possible for a modem to receive more than 100 grants per second. If every grant were the size of the modem's allowed maximum burst size (as configured by, e.g., Maximum Concatenated Burst, [J.122]), an upper bound on the modem's performance could be found by the following simple calculation:
+
+$$\text{max throughput (bits/s)} = \text{max burst (bits)} \cdot 1/[\text{round trip time (s)}]$$
+
+In practice, due to the need to share bandwidth among many users and services, the maximum burst size must be limited to reasonable values, and the CMTS generally cannot grant the maximum burst size in every grant, even if a modem requests it.
+
+A longer round-trip time also increases the access latency seen by a single modem – i.e., the time it takes for a modem to gain access to the upstream to begin transmission of new data after an idle period. Conversely, if reducing round-trip time enables higher throughput to be achieved or speeds the opening of the TCP window, the modem's transactions (e.g., download of an FTP file or HTTP web page) may be completed more quickly (assuming plant bandwidth is available to do so). These factors may in turn affect the overall bandwidth efficiency of the system.
+
+### I.3 Elements of round-trip time
+
+It is convenient to begin measurement of round-trip time at the instant when a modem begins transmission of a request. Round-trip time can then be measured as the time from this initial request to the instant when the modem begins transmission of its next request. These events can easily be captured on a network sniffer.
+
+The elements of round-trip time may be categorized as follows:
+
+- *Upstream propagation delay*: Time occupied by plant delays in the upstream direction.
+- *Upstream reception and request parsing time*: Time from the start of burst arrival at the CMTS until reception and parsing of the request is complete. Some CMTSs require that the entire burst be received before it can be parsed. Others can recognize piggyback requests near the beginning of a burst, even if the end of that burst has not yet arrived. If FEC is enabled for the burst, at least one full FEC block must be received and decoded before any MAC-layer parsing can be performed.
+
+- *Scheduler queueing and processing delay:* Time from arrival of the request at the scheduler until completion of the MAP message containing a grant for the request. If the request arrives just after the scheduler has finished creating a MAP, the request is delayed by the time interval until the next MAP. On the other hand, if the request arrives just before the scheduler finishes creating a MAP, the request may see nearly zero delay. In general, the actual queueing delay is a random variable between zero and the maximum MAP interval. Under some lab conditions involving only one or a few CMs, this delay may appear to be constant, but this cannot generally be assumed in a real system. Some scheduler implementations may vary the MAP interval to optimize this delay.
+
+The time required for the scheduler to make scheduling decisions and actually create the MAP message is also included here. This factor is highly implementation-dependent.
+
+- *MAP delivery time (to the EQAM DOCSIS PHY layer):* The time from the completion of the MAP message creation, to delivery of the MAP to the PHY layer. This includes any time consumed by the M-CMTS Core's MAC function; encapsulation of the MAP into a DEPI packet; queueing and transmission of the DEPI packet at the egress of the M-CMTS Core; delay and jitter of the CIN; queueing and processing delays inside the EQAM; and any delay in inserting the MAP into the MPEG-encapsulated DOCSIS stream (e.g., due to the need to wait for a previous packet to complete transmission).
+- *Downstream physical-layer delays:* This includes the latency of the downstream modulator, downstream interleaver delay, and physical propagation delay between the EQAM and the CM.
+- *CM MAP processing time:* The time from arrival of the first bit of the MAP at the CM, until the MAP becomes effective. The minimum value is specified in the Relative Processing Delay clause of [J.122]. It accounts for all internal CM processing delays.
+- *Time until grant:* If the first grant in the MAP is not to this CM, the CM's actual transmission will be "delayed" until the actual time of the grant.
+- *Margin:* In practice, the CMTS cannot precisely control all delays to guarantee that MAPs arrive at the modem at exactly the right instant. Thus, the CMTS must add margin to account for worst-case propagation delays to the farthest modems, variations in MAP creation time and CIN delays, etc.
+
+Table I.1 lists example values for the round-trip time components described above. These values are given ONLY by way of example and should not be interpreted as typical values applying to any particular system and/or implementation.
+
+**Table I.1/J.212 – DOCSIS Request-Grant round trip worksheet**
+
+| Delay source:                                         | (All time values in usec) |                       | Remarks                                       |
+|-------------------------------------------------------|---------------------------|-----------------------|-----------------------------------------------|
+|                                                       | subtotal                  | total                 |                                               |
+| <b>Upstream propagation time</b>                      |                           | <b>800</b>            |                                               |
+| Physical HFC plant delay                              | 800                       |                       | apprx 100 miles                               |
+| <b>Upstream reception/parsing time</b>                |                           | <b>469</b>            |                                               |
+| upstream PHY processing time                          | 369                       |                       | time for 1 FEC block (236,200) at 5.12 Mbit/s |
+| upstream MAC processing time                          | 100                       |                       |                                               |
+| <b>Scheduler queueing and processing</b>              |                           | <b>1000</b>           |                                               |
+| <b>MAP delivery to PHY layer</b>                      |                           | <b>1338</b>           |                                               |
+| DEPI packetization at Core                            | 383                       | <b>plus CIN delay</b> | for MPT mode, transmit time of 7 MPEG packets |
+| CIN delay                                             | varies                    |                       |                                               |
+| EQAM latency                                          | 500                       |                       | per J.212                                     |
+| Queueing behind max-length packet during MPEG encaps. | 455                       |                       | transmit time of 1518 bytes (64QAM Annex B)   |
+| <b>Downstream transmission time</b>                   |                           | <b>1841</b>           |                                               |
+| MAP duration on wire                                  | 61                        |                       | 200B MAP at 64QAM                             |
+| downstream FEC/interleaver delay                      | 980                       |                       | (I, J) = (32,4) at 64QAM                      |
+| downstream prop. delay                                | 800                       |                       | apprx 100 miles                               |
+| <b>MAP Advance Margin</b>                             |                           | <b>500</b>            |                                               |
+| <b>CM processing time</b>                             |                           | <b>200</b>            | TDMA, no byte interleaving                    |
+| <b>Total round trip time</b>                          |                           | <b>6148</b>           |                                               |
+|                                                       |                           | <b>plus CIN delay</b> |                                               |
+
+### I.4 CIN characteristics
+
+In an M-CMTS system, the CIN adds delay which may be a noticeable contributor to the total system round-trip time. The CIN is configured and managed by the operator. Its extent may vary widely from one system to the next. It may be as simple as a short Ethernet cable between one M-CMTS Core and one EdgeQAM. Alternatively, it may be an IP network consisting of multiple switch and/or router hops which is shared with other (non-DEPI) traffic to and from other nodes (e.g., IP-encapsulated video from VoD servers).
+
+All but the most trivial of packet-based networks will experience variations in delay. These variations arise due to variability in length and arrival time of packets, changes in instantaneous loading, queuing of packets within network elements, differences in QoS parameters applied to different packets, and other factors. Thus, network delay is often modelled as a random variable.
+
+One common way of describing network delay is as a sum of two components: a "typical" delay which is treated as a constant, plus a "jitter" term which may differ from packet to packet. Another approach is to describe the network as having a "minimum" delay and a "maximum" or "worst-case" delay, with delays on individual packets distributed between the two extremes in some way. These approaches are often convenient ways of approximating network behaviour.
+
+One approach to rigorously modelling the network involves determining a Cumulative Distribution Function (CDF) of packet delays. This CDF is a function or graph in which the x-axis shows delay  $D_0$ , while the y-axis shows the probability that the actual delay  $D$  on any particular packet is less than  $D_0$ . To be useful, this CDF may be limited in scope: for example, it may be from some specified source node to a particular destination node and for a particular class of traffic. It can then be stated that a certain fraction of applicable packets will experience delay less than a particular amount (e.g., "99.995% of packets will experience delay less than 2 ms", or some similar statement). In some networks, it may be impossible to guarantee an upper bound on delay for 100% of all packets.
+
+In addition to the CIN itself, the "network" may include switching and/or queuing that occurs inside an M-CMTS Core or an EQAM. For example, an M-CMTS Core supporting multiple downstream QAM channels may have multiple Gigabit Ethernet output ports, and thus might include an internal "switch" to connect various DEPI flows to different output ports. If present, this switching function could also add implementation-dependent queuing delays which could be modelled as part of the CIN.
+
+To aid in characterizing the CIN, DEPI specifies the Latency Measurement Subheader (clause 8.4). This subheader takes advantage of the fact that both the M-CMTS Core and the EQAM contain a DTI interface which provides a common, high precision clock. The M-CMTS Core transmits a Latency Measurement Packet, on any given DEPI session, containing its current timestamp value. Upon receipt of this message, the EQAM adds its own timestamp value and returns both values to the M-CMTS Core. The result is a single measurement of CIN delay (plus any M-CMTS Core egress and EQAM input queueing delays in the path between timestamp insertion points) between the CMTS and the EQAM. The CMTS may make use of this information in several different ways including CDF calculations or adjusting specific DOCSIS network parameters.
+
+Oftentimes the design of the CIN is the one variable in the M-CMTS architecture that the operator has complete control over. Decisions made here regarding the size and number of network hops will have a direct effect on overall performance of the DOCSIS network.
+
+### 1.5 Queueing delays in network elements
+
+Many layer 2 and layer 3 switch products today support line-rate switching in a non-blocking fashion. "Non-blocking" means that packets being switched across particular source and destination ports will not interfere with packets being switched across different source and destination ports. If all traffic within the switch is non-blocking (as is typically the case in laboratory tests per IETF RFCs), switching will be very fast. (Exact values for this "intrinsic switch delay" are implementation-specific.) However, if packets simultaneously arriving from several different source ports are directed to a single destination port, these packets will suffer queueing delay within the switch.
+
+For very simple switched topologies where only DEPI traffic is present, worst-case queueing delay at a given destination port may be calculated as a function of packet size and number of source ports switching to that destination port. This calculation only applies to a single node within the network.
+
+If every source port delivered a packet to the destination port at the same instant, the last of these packets to actually exit the destination port would be delayed by the time required to transmit all preceding packets. The calculation is as follows:
+
+$$\text{Max delay (s)} = (\# \text{ of source ports} - 1) \cdot \text{packet size (bits)} / \text{line rate (bits/s)}$$
+
+The result of this calculation plus the intrinsic switch delay (which may, by way of example, be on the order of 10-100  $\mu\text{s}$ ) gives a reasonable upper bound on the total worst-case delay through the switch when the traffic at the source ports is rate-limited by the M-CMTS Core. As a result, the aggregate traffic out the destination port of the switch does not exceed the port's capacity. This would typically be the case for a switch internal to a CMTS or EQAM, or one that carries only DEPI traffic in a one- or two-hop network. For more complex systems, additional queue build-up could occur and the latency through the switch could easily exceed 1 ms. As such, it is important to apply QoS policies to any traffic that is latency sensitive so that it might bypass queue build-ups. More information on the use of QoS in the CIN is provided in the clauses below on "Traffic Prioritization" and "PSP Mode".
+
+In recent years products have evolved so that the distinction between a "switch" and a "router" is not always clear. A "switch" may incorporate extensive QoS functionality, while a "router" may perform large amounts of processing in hardware and be as fast as some switches. Thus, in more complex CIN topologies, delays may vary widely and do not readily lend themselves to calculation. Even routers or switches capable of line-rate performance are subject to congestion and internal queueing and processing delays which may vary depending on the load, traffic type, QoS functions supported, and many other conditions.
+
+### I.6 Traffic prioritization and network delays
+
+In general, it is possible to reduce network delay for certain packets by instructing routers and/or switches to give these packets higher priority than other packets. The mechanism for accomplishing this is usually the IEEE 802.1Q VLAN tag for Ethernet, or the DSCP field and associated per-hop behaviour for IP.
+
+In the simplest case, packets tagged as high priority are sent by the router or switch ahead of all other packets of lower priority which may already be queued within the device. More complex behaviours also exist, but fundamentally, they all reduce delay on the high-priority packets at the expense of lower-priority packets. In order for this to be effective, high-priority packets must represent a relatively small fraction of the total traffic on the network.
+
+In a CIN, traffic prioritization may be useful for reducing round-trip time when PSP mode is in use by prioritizing DEPI flows containing MAPs ahead of flows containing other types of data. This concept may be extended to add more priority levels (e.g., for voice vs best-effort data) if the M-CMTS Core and EQAM both support the desired number of PSP flows. In MPT mode, this approach cannot be used since all data for a given QAM channel, regardless of type or priority, are carried in a single flow.
+
+If the CIN also carries non-DEPI traffic, it may be possible to reduce DEPI delays by giving DEPI higher priority. However, this will result in increased delay on the non-DEPI packets. The consequences of this should be carefully considered by the operator.
+
+### I.7 Queue persistence in a DEPI flow
+
+DEPI requires the M-CMTS Core to rate-shape its output to match the rate of the EQAM's RF output. If the path between the two devices had fixed delay (i.e., zero jitter), DEPI data arriving at the EQAM would immediately be transmitted on the HFC network. In practice, a real DEPI path will always contain variable delays (i.e., jitter). The presence of jitter in this path requires data to be queued inside the EQAM.
+
+To see this, consider a simple example involving a single MPT-mode DEPI flow. Suppose that packets are being sent on a 1 Gbit/s Ethernet network. The flow itself occupies only about 40 Mbit/s and is rate-shaped, so there will be "space" on the network between packets. The interval on the CIN between the start of one packet and the start of the next packet will correspond to the same interval on the EQAM's RF output. As long as every packet is being delivered from M-CMTS Core to EQAM with constant delay  $D$ , each packet will arrive at the EQAM just as the EQAM completes transmission of the previous packet. However, suppose a single packet  $P_0$  experiences higher-than-normal delay  $D + J$ . The time on the network between this packet and the previous one (packet  $P_{-1}$ ) is extended, while the time between this packet and the following one (packet  $P_1$ ) is compressed (since  $P_1$  experiences only delay  $D$ ). Thus, the EQAM completes transmission of  $P_{-1}$  before  $P_0$  arrives. Since the EQAM now has no DOCSIS data to send, it must transmit MPEG Null packets until  $P_0$  arrives. At that time, it must complete the MPEG Null packet it is currently transmitting and then begin transmission of  $P_0$ . However, since the time between  $P_0$  and  $P_1$  has been shortened,  $P_1$  will arrive at the EQAM before transmission of  $P_0$  has completed.  $P_1$  must now be queued by the EQAM and will experience queueing delay  $J'$ , where:
+
+$$J' = \text{ceiling}(J/T_{\text{MPEG}}), \text{ where } T_{\text{MPEG}} = \text{duration of one MPEG packet}$$
+
+i.e., the amount of delay that was added to  $P_0$  due to jitter on the network rounded up to the next MPEG packet boundary. In addition, as long as the M-CMTS Core continues to output data at the exact rate of the EQAM's RF output, all subsequent packets in the flow will also experience queueing delay  $J'$ . This can be a serious problem for an M-CMTS system, since even if jitter  $J$  occurs very infrequently, once it does occur, the additional queueing delay could persist indefinitely.
+
+To prevent this infinite queue persistence, DEPI requires that the M-CMTS Core be capable of rate-shaping its output to some configurable fraction of the EQAM's actual output data rate. This does not prevent queueing delays from occurring due to network jitter events, but it does mean that, in the aggregate, the EQAM can drain the queue (by transmitting data) faster than it fills.
+
+It is possible to calculate the time  $T$  required for the queue depth to return to zero after a jitter event increases the delay on a single packet from  $D$  to  $D + J$ . Suppose that the CMTS is rate-shaping to a rate  $r$  which is some "rate-shaping ratio"  $\rho$  of the EQAM's output rate  $R$  (i.e.,  $\rho = r/R$ ). During time  $J'$ , it will send MPEG Null packets when, had the jitter event not occurred, it would have ordinarily received from the M-CMTS Core and immediately transmitted on the wire  $J' \cdot r$  bits of data. This number of bits will instead be queued inside the EQAM and, once available, transmitted and hence removed from the queue at rate  $R$ . Meanwhile, data continues to arrive and be added to the queue at rate  $r$ . Thus, over a time interval  $T$ , the total queue size decreases by  $T \cdot (R - r)$ . The queue size will return to zero when:
+
+$$J' \cdot r = T \cdot (R - r)$$
+
+Solving for  $T$  and expressing in terms of  $\rho$  (the ratio configured in the M-CMTS Core) gives:
+
+$$T = J' \cdot \rho / (1 - \rho)$$
+
+For example, if network jitter on a single packet results in 2 ms of queueing delay ( $J'$ ), and the M-CMTS Core continues to send traffic at a rate equal to 98% of the EQAM's actual output rate, the time to drain the resulting queue at the EQAM will be (2 ms)  $[0.98/(1 - 0.98)]$ , or 98 ms. This time will be reduced if the CMTS does not have enough downstream traffic available during this period to "fill the pipe" to 98% of nominal. Conversely, if another network jitter event occurs before this time has elapsed, the queue size will again suddenly increase. The impacts of continuous jitter is not additive. Rather, the worst-case queue build-up will equal the worst-case jitter. If network jitter events are frequent enough and traffic load remains relatively high, the queue may never completely drain.
+
+For MPT operation, a single flow contains all DOCSIS data for a given QAM channel, including MAP messages. The above calculation of  $T$  can be useful in estimating how many MAP messages will experience increased delay due to network jitter events. If a MAP interval is typically 2 ms, then during time  $T = 98$  ms, 49 MAP messages on each upstream channel will see increased delay as a result of each network jitter event adding  $J = 2$  ms delay to a single DEPI packet (whether or not that packet contains a MAP message). Note that this calculation may not be exact, since the CMTS may vary the MAP interval.
+
+Depending on how much MAP Advance margin the CMTS has provided (see round-trip time calculations in Clause I.3), some of these 49 MAPs may still be usable by CMs. To account for this, the amount of margin provided may be subtracted from  $J$  and the result used to calculate  $T$ , i.e., if margin is represented by  $\mu$ , then when a jitter event occurs which adds jitter  $J$ , the number of MAPs on each upstream channel which are delayed enough to be lost is given by:
+
+$$\# \text{ MAPs lost} = [(J - \mu) \cdot p / (1 - p)] / (\text{MAP interval})$$
+
+In the current example, if the CMTS has added 500  $\mu\text{s}$  of MAP Advance margin to each MAP, the queue would drain to the point where MAPs are usable by CMs after  $(J - 500 \mu\text{s}) \cdot [p / (1 - p)] = (1.5 \text{ ms}) (49) = 73.5 \text{ ms}$ . If the MAP interval is 2 ms, only 37 MAPs would be lost for each such network jitter event, as opposed to the 49 MAPs that would be lost if zero margin had been provided. These 37 lost MAPs translate into  $(37 \cdot 2 \text{ ms}) = 74 \text{ ms}$  of time during which CMs cannot transmit as a result.
+
+To minimize the number of MAPs lost due to network jitter when MPT mode is in use, the scheduler should add margin sufficient to give the desired reliability level, based on the CDF describing the network. For instance, suppose it has been determined that 99.9999% of the time (i.e.,  $1 - 10^{-6}$ ), the network delay will be less than  $D_1$ . The scheduler could then add a margin of  $D_1$  when creating MAPs. It could then be said that an event resulting in lost MAPs will occur once for every  $10^6$  packets sent. On a relatively loaded downstream carrying, e.g., 50,000 packets per second, this would result in a "lost MAP event" about once every 20 seconds. The number of MAPs lost for each event, and the corresponding time for which CMs cannot transmit due to missing MAPs, would depend on the amount by which the actual delay exceeded  $D_1$ . In the previous example, if the MAP Advance margin had been set to 2 ms to account for the worst case CIN jitter, then the 49 MAP messages that were delayed would all still be usable.
+
+The effect of this added margin is to increase system round-trip time by  $D_1$  for all packets. However, it helps to minimize the negative system impacts of frequently lost MAPs.
+
+### I.8 PSP mode
+
+DEPI provides PSP mode as a way of mitigating CIN delays affecting round-trip time. PSP mode does not reduce the delay of the network itself. Instead, it separates MAP messages into a separate DEPI flow and uses traffic prioritization (clause I.6) to minimize delay on this flow. PSP mode also allows the EQAM to transmit MAP messages ahead of lower-priority DOCSIS data, even if the lower-priority data is already queued within the EQAM. These two modifications in turn mean that, in PSP mode:
+
+- MAP messages are only delayed in the network by jitter events directly affecting packets containing MAPs; and
+- MAP messages can only be queued behind (and hence delayed by) other MAPs. Thus, the CDF for network delay for MAP messages in PSP mode may show significantly lower delays than a similar CDF for MPT mode on the same network.
+
+Use of PSP mode should be considered by the operator whenever the impact of the CIN on system round-trip time is a concern. More specifically, PSP mode should be considered if the amount of margin which must be added to round-trip time to give a low enough rate of lost MAPs is unacceptably large. What exactly constitutes "unacceptably large" depends on many factors and
+
+may be subjective. For example, a system in which the plant is physically short has less propagation delay and therefore may tolerate larger CIN delays. As another example, on a plant where high modem performance is desired but the presence of UGS traffic or other factors compel the use of a small maximum burst size, even relatively small CIN delays may degrade performance.
+
+In general, a very small CIN (one or possibly two switch hops) probably has little impact on system round-trip time, while a CIN which has multiple hops and/or on which non-DEPI traffic is present probably has a much more significant impact on system round-trip time. To accurately predict the actual improvement in round-trip time that can be gained by using PSP mode on a given CIN, it is necessary to characterize the delays of that CIN for different DSCPs.
+
+# Appendix II
+
+## Early adoption and evolving use of EQAM devices
+
+Prior to the development of the M-CMTS Recommendations, EQAM devices in existing HFC digital CATV systems were responsible for video processing functions such as multiplexing and modulation (QAM). The M-CMTS Recommendations place additional requirements on EQAM devices to support DOCSIS functionality.
+
+It is possible that certain EQAM devices may be able to support a subset of the DOCSIS functionality by adhering to parts of the M-CMTS Recommendations (including DEPI). These devices would not be considered M-CMTS compliant EQAMs, but nonetheless might be a valuable component of a transition strategy for operators.
+
+The development of initial M-CMTS EQAM devices that are first on the market (early adopters) will be divided into two categories. The first category (category A) is EQAM vendors with existing video-only EQAM products (no support for the DTI). These vendors may want to offer their customers a software upgrade path for already deployed EQAM products to support bonded DOCSIS channels that do not contain timing information (no SYNC messages). The second category (category B) is EQAM vendors that intend to initially offer new EQAM products that have fully M-CMTS capable hardware including the DTI, but where full support for M-CMTS features is not offered initially. In both categories, support for additional M-CMTS features would typically be added via software upgrade using a phased approach.
+
+### II.1 EQAM development: Category A (no DTI)
+
+Vendors falling into Category A will provide software upgrades to allow their existing deployed video EQAM products to be upgraded in the field to support bonded DOCSIS channels that do not contain DOCSIS timing information (no SYNC messages). This provides a level of investment protection for operators with already deployed EQAM products in the field. These upgraded video EQAM products would not support the DTI and would thus not be M-CMTS compliant, but they could be leveraged by operators when deploying DOCSIS channel bonding. This would help to minimize the number of new EQAM devices that the operators would be required to purchase when upgrading their systems to support DOCSIS channel bonding.
+
+Upgrade Phases for Category A (no DTI):
+
+- Phase 1: S/W upgrade existing "video" EQAM to support {L2TP control plane and DEPI MPT mode}
+- Phase 2: Add (to phase 1) support for L2TP data plane.
+- Phase 3: Add (to phase 2) support for ERMI.
+
+### **II.2 EQAM development: Category B (with DTI)**
+
+Vendors falling into Category B will initially develop EQAM devices with hardware that has the capability of achieving full M-CMTS compliance. This mainly includes the physical DTI interface hardware. Support for M-CMTS features will then be phased in by the vendor over time by offering software upgrades. This allows operators to purchase M-CMTS EQAM devices up front knowing that only software upgrades are required to eventually achieve full M-CMTS compliance. An EQAM with M-CMTS compliant hardware would support the DTI allowing it to operate in either SCDMA mode or ATDMA mode.
+
+Upgrade Phases for Category B (with DTI):
+
+- Phase 1: Support DTI, L2TP control plane, and DEPI MPT mode.
+- Phase 2: Add (to phase 1) support for L2TP data plane.
+- Phase 3: Add (to phase 2) support for ERMI.
+- Phase 4: Add (to phase 3) support for DEPI: PSP mode.
+
+### **II.3 Possible M-CMTS feature phasing**
+
+In order to minimize time to market, EQAM vendors will likely add in support for M-CMTS system features using a phased approach by offering software upgrades. In both development categories described above (A and B), the software upgrade path towards full M-CMTS compliance may be very similar.
+
+#### **Development: Phase 1**
+
+The initial M-CMTS products will support the L2TP control plane, and they will likely support the DEPI MPT mode only (not DEPI PSP mode). EQAMs with DTI hardware may or may not support the DTI. If the DTI is not supported, the EQAM can only be used for video applications and or to support DOCSIS bonded channels with no DOCSIS timing information.
+
+The L2TP control plane is required to allow the M-CMTS core to provision and configure the EQAM, so support for the L2TP control plane is mandatory. It is assumed that the L2TP control plane can be developed in software with no required hardware changes to either an existing "video" EQAM or an EQAM with M-CMTS capable hardware.
+
+Support for the L2TP data plane may require hardware assistance or more extensive software development than the L2TP control plane, so it is likely that EQAM vendors would defer support of the L2TP data plane until later phases. Existing network processors typically do not support the L2TP, so any L2TP data plane processing in early adopter EQAM products would require custom software development. It should also be noted that the M-CMTS core will always include the L2TP data plane, but since the L2TP layers are fixed length, an early adopter EQAM product could be designed to simply skip over the L2TP headers when receiving DEPI data. In this case the UDP layer is required to support the routing of data packets to the appropriate QAM channel outputs.
+
+It is likely that the early adopter EQAM devices will initially support the DEPI MPT mode, but not the DEPI PSP mode. The DEPI MPT mode delivers MPEG packets to the EQAM, and requires processing in the EQAM that is similar to the processing that is performed on video MPEG packets. The DEPI PSP mode requires the EQAM to perform additional functions such as transmission convergence (MPEG packetization) and DOCSIS SYNC insertion so it will likely be deferred to a later phase.
+
+#### **Development: Phase 2**
+
+It is likely that the next step (phase 2) after offering initial EQAM products as described above in phase 1 would be to offer support for the L2TP data plane. Support of the L2TP data plane could be realized in software, or network processors that support the L2TP could be leveraged if available.
+
+The use of L2TP capable network processors could be achieved via software upgrade and or an FPGA firmware upgrade, or hardware changes could be required.
+
+#### **Development: Phase 3**
+
+Support for the M-CMTS ERMI will also be phased in via software upgrade. The M-CMTS system is designed to function without an ERM (without the use of the ERMI) by relying on the L2TP control plane and static system configuration. In this case, EQAM resources are manually (and statically) assigned to the M-CMTS core. As a result, support for the ERMI in the EQAM can be deferred until a later phase.
+
+#### **Development: Phase 4**
+
+The final phase of M-CMTS EQAM development is likely to be software upgrades to support the DEPI PSP mode. The DEPI PSP mode requires the EQAM to perform DOCSIS specific functions such as transmission convergence (MPEG packetization) and DOCSIS SYNC insertion. In addition, the data plane processing for PSP mode is more complex than MPT mode in that it requires support of variable size PDUs with multiple DOCSIS frames per PDU. As a result, it is likely that support for DEPI PSP mode will be offered by EQAM vendors in late or final phases of development. Support for DEPI PSP mode would only be applicable to EQAM products that support the DTI (category B EQAM products).
+
+## **II.4 Optional UDP layer**
+
+The UDP layer is optional in the L2TP. It is desirable to use the L2TP protocol without the UDP layer since the L2TP provides built in mechanisms (session IDs) to bind payload data to software functions analogous to the use of a UDP port. If two devices that fully support the L2TP are communicating with each other (using L2TP), then there is no need to use a UDP layer below the L2TP layer since the session ID field provides the necessary data routing function. If one of the devices does not support the L2TP in the data plane, then the UDP layer can be used to provide the data routing function.
+
+Since off-the-shelf network processors that support the L2TP will likely not be available when EQAM vendor begin M-CMTS development, early adopter EQAM products will likely not support the L2TP in the data plane. As a result, early adopter EQAM products will likely make use of the UDP layer to provide the data routing function since existing network processors are capable of parsing packets up to and including the transport layer in hardware.
+
+Eventually, if/when L2TP capable network processors become available, or alternatively if EQAM vendors develop support for the L2TP layer in the data plane, the devices communicating via L2TP can stop using the UDP layer if desired.
+
+
+
+
+
+# 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.215**
+
+(12/2007)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Interactive systems for digital television distribution
+
+# --- **Client digital program insertion API**
+
+Recommendation ITU-T J.215
+
+
+
+## **Recommendation ITU-T J.215**
+
+# **Client digital program insertion API**
+
+## **Summary**
+
+The digital program insertion (DPI) Recommendations given in ITU-T J.181 and ITU-T J.280 have enabled cable operators to provide local ad insertion on digital content at a head-end level, using equipment available from multiple vendors. Recommendation ITU-T J.215 enables similar functionality for DPI including addressable commercials, or other content, to be inserted at a device level in the consumer premises equipment.
+
+## **Source**
+
+Recommendation ITU-T J.215 was approved on 14 December 2007 by ITU-T Study Group 9 (2005-2008) under the ITU-T Recommendation A.8 procedures.
+
+# 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2010
+
+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    |
+| 2.1 Normative References .....                          | 1    |
+| 2.2 Informative References .....                        | 1    |
+| 3 Definitions .....                                     | 1    |
+| 4 Acronyms.....                                         | 2    |
+| 5 Conventions .....                                     | 2    |
+| 6 DPI overview .....                                    | 3    |
+| 7 Requirements for digital program insertion (DPI)..... | 4    |
+| 7.1 DPI signalling.....                                 | 4    |
+| 7.2 Switch engine behaviour .....                       | 7    |
+| 7.3 Switch Engine API .....                             | 8    |
+| Annex A – OCAP 1.1 Digital Program Insertion API.....   | 12   |
+| A.1 SwitchEngineException class.....                    | 12   |
+| A.2 SwitchEngineListener interface.....                 | 13   |
+| A.3 SwitchEngineManager Class.....                      | 16   |
+| A.4 SwitchInstruction Class .....                       | 19   |
+
+
+
+## Recommendation ITU-T J.215
+
+# Client digital program insertion API
+
+# 1 Scope
+
+This Recommendation defines requirements for digital program insertion, henceforth referred to as DPI.
+
+This recommendation enables digital program insertion in host devices ("client devices") within customers' homes, enabling addressable commercials to be inserted and addressed at a household level (or even at an individual television set level).
+
+# 2 References
+
+## 2.1 Normative 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 J.202] Recommendation ITU-T J.202 (2005), *Harmonization of procedural content formats for interactive TV applications.*
+- [ITU-T J.280] Recommendation ITU-T J.280 (2005), *Digital Program Insertion: Splicing application program interface.*
+- [DVB-SAD] ETSI TS 102 823 v1.1.1 (2005), *Digital Video Broadcasting (DVB); Specification for the carriage of synchronized auxiliary data in DVB transport streams*, <<http://pda.etsi.org/pda/queryform.asp>>.
+- [ANSI/SCTE 138] ANSI/SCTE 138 (2009), *Stream Conditioning for Switching of Addressable Content in Digital Television Receivers.*
+
+## 2.2 Informative references
+
+- [ITU-T J.181] Recommendation ITU-T J.181 (2004), *Digital program insertion cueing message for cable television systems.*
+- [ITU-T J.201] Recommendation ITU-T J.201 (2004), *Harmonization of declarative content format for interactive television applications.*
+
+# 3 Definitions
+
+This Recommendation defines the following terms:
+
+**3.1 application:** An application is a functional implementation realized as software running in one or spread over several interplaying hardware entities.
+
+**3.2 application program interface (API):** An application program interface is the software interface to system services or software libraries. An API can consist of classes, function calls, subroutine calls, descriptive tags, etc.
+
+- 3.3 broadcast:** A broadcast is a service that is delivered to all customers. Each customer may select a particular broadcast channel out of many.
+- 3.4 broadcast application:** A broadcast application is an application running on the set-top converter that is loaded through in-band information, inserted either at the head-end or by a content provider farther upstream.
+- 3.5 client device:** The CPE that is connected to the cable network in the consumer's home, receives the television signals at the client's premises, and presents it for display on a display device.
+- 3.6 digital program insertion (DPI):** Insertion of alternative content into digitally encoded content in response to messaging in the stream.
+- 3.7 packet identifier (PID):** MPEG-2 assigns a PID to each data packet. Packets with the same PID belong to the same logical channel.
+- 3.8 program map table (PMT):** This is a MPEG-2 entity that contains all of the PIDs that make up a program.
+- 3.9 switch engine:** This term refers to the functionality that executes switching in the host device. This switching can either be seamless, or non-seamless. Because this functionality needs to be implemented in a real-time way, with predictable timing behaviour, the switching engine is implemented as part of an OpenCable Applications Platform (OCAP) implementation ("below the line"). It exposes an API to OCAP applications (targeting engines) to select which commercials are switched to/from. A switching engine can be implemented in hardware, software, or a combination of both.
+- 3.10 unicast advertising:** Advertising content directed at a single target or small group of targets.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations:
+
+|      |                                 |
+|------|---------------------------------|
+| API  | Application Program Interface   |
+| DPI  | Digital Program Insertion       |
+| OCAP | OpenCable Applications Platform |
+| PMT  | Program Map Table               |
+
+# 5 Conventions
+
+The following words are used throughout this Recommendation to define the significance of particular requirements:
+
+|            |                                                                                                                                                                                                                                                |
+|------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| SHALL      | This word, or the adjective REQUIRED, means that the item is an absolute requirement of this Recommendation.                                                                                                                                   |
+| SHALL NOT  | This phrase means that the item is an absolute prohibition of this Recommendation.                                                                                                                                                             |
+| SHOULD     | This word, or the adjective RECOMMENDED, means that valid reasons may exist in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighed before choosing a different course. |
+| SHOULD NOT | This phrase means that there may exist valid reasons in particular circumstances when the listed behaviour is acceptable or even useful, but the                                                                                               |
+
+full implications should be understood and the case carefully weighed before implementing any behaviour described with this label.
+
+MAY
+
+This word, or the adjective OPTIONAL, means that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product, for example; another vendor may omit the same item.
+
+# 6 DPI overview
+
+The digital program insertion (DPI) standards within [ITU-T J.181] and [ITU-T J.280] have enabled cable operators to provide local ad insertion on digital content at a head-end level, using equipment available from multiple vendors. This Recommendation enables similar functionality for DPI including addressable commercials, or other content, to be inserted at a device level.
+
+To allow for programmability by a cable operator as well as meet time sensitive insertion requirements, the DPI functionality is separated into two logical components: a 'switch engine' implemented as part of the J.201 platform that performs real-time functions of switching between programs and program elements, and one or more 'targeting engine' applications that control the behaviour of the switch engine.
+
+A switch engine performs switch operations to present inserted content. In the broadcast scenario, which is the only scenario defined herein, inserted content MAY be within the same MPEG-2 transport stream as the original program or broadcast within a different MPEG-2 transport stream. Other scenarios, such as those where the original or inserted content are available on a storage device, may be defined elsewhere.
+
+A switch engine implements two distinct types of switches; a Level 0 (L0) switch, which appears to the viewer as a channel change, and a Level 1 (L1) switch, which is totally invisible to the viewer. During an L0 switch, a switch engine may be required to tune to a different channel to access an insertion stream. An L1 switch never requires tuning; in this case, all of the insertion streams are within the same transport stream as the original program content.
+
+Requirements on content to enable L0 and L1 switches are defined by [ANSI/SCTE 138]. The switch engine behaviour is defined in clause 7.2. Detailed requirements on OCAP to perform L0 and L1 switches are defined in Annex A.
+
+An illustration of the logical components of the OCAP DPI capability is provided in Annex A.
+
+![Figure 1 – OCAP DPI overview diagram showing the logical components of the OCAP DPI capability within a Host device.](99bae07626f60f9ede10e2e387ef7051_img.jpg)
+
+The diagram illustrates the logical components of the OCAP DPI capability within a Host device. The Host device contains a CPE (Customer Premises Equipment) block, which is further divided into Applications and System software. The Applications block includes Targeting engine(s) and OCAP DPI API (1). The System software block includes the Switch engine. The CPE is connected to a Middleware API. The Middleware API is connected to DPI Signalling (2) and Content Feeds (3). The System software block is connected to Optional storage. The System software block is also connected to a large arrow pointing to the right, labeled 'To display'. A feedback loop labeled 'Application command and control (out of scope)' connects the Targeting engine(s) back to the Applications block. The diagram is labeled J.215(07)\_F01.
+
+Figure 1 – OCAP DPI overview diagram showing the logical components of the OCAP DPI capability within a Host device.
+
+Figure 1 – OCAP DPI overview
+
+Indicated as (1) in Figure 1, a targeting engine API is defined Annex A to enable applications to provide the switch engine with instructions and to receive status information on previously submitted instructions.
+
+Indicated as (2) in Figure 1, DPI signalling are messages that are processed by the switch engine. Signalling may be in the form of DPI triggers or timelines. See clause 7.1 below for detailed requirements on processing DPI signalling.
+
+Where instructed by a targeting engine, the switch engine performs a program insertion operation on receipt of a DPI trigger, or based on a timeline. The DPI API provides the mechanism by which a targeting engine application configures the switch engine to perform a switch operation. A switch operation occurs when the switch engine is properly configured by a targeting application through the DPI API, and the proper signalling is subsequently detected.
+
+Indicated as (3) in Figure 1, content feeds are MPEG-2 transport streams that carry program feeds and may contain other insertion feeds, such as advertising feeds. The program feeds (as well as the separate insertion feeds) may contain DPI signalling that is used by the switch engine to insert content, such as addressable commercials during addressable breaks. The program feeds and insertion feeds may be subject to certain encoding (and other) restrictions that make it easier for the switching engine to switch to and from insertion content, see [ANSI/SCTE 138].
+
+The command and control element shown in Figure 1 represents a hypothetical private communication channel between a targeting engine and an associated network component. Advanced advertising systems are expected to incorporate logical components within the cable network that manage both the insertion of DPI signalling and the actions of a targeting engine.
+
+No security model has been defined to protect signalling from detection by non-authorized users. Because of the extremely tight synchronization between signalling and video content needed to perform seamless L1 switches, signalling must be in-band, in the same program stream as the original content feed. Strategies for obfuscating signals may be developed, but none are described herein.
+
+# 7 Requirements for digital program insertion (DPI)
+
+## 7.1 DPI signalling
+
+This clause describes signaling used to enable a switch engine to perform its operations.
+
+Two signalling protocols are used to support DPI: DPI triggers and DPI timelines. DPI trigger messages embedded within a content segment indicate opportunities to perform a switch operation. DPI timelines are messages embedded within a content segment to enable the implementation to maintain a metadata timeline for a segment. Switch operations MAY be based on timelines.
+
+All DPI signalling is expected to be carried on a single data PID within the original content stream. This data stream SHALL be identified by DPI registration descriptor in a program's PMT.
+
+![Figure 2 – DPI signalling stream. A diagram showing a Program 1 with four PIDs: PMT (PID 1), Video (PID 2), Audio (PID 3), and DVB-SAD (PID 4). The DVB-SAD stream is shown as a sequence of segments over time. Key events are marked: 'SAD Timeline descriptor' (yellow), 'L0 Trigger SAD stream event' (red), and 'L1 Trigger pair SAD stream event' (green). Vertical lines indicate 'Insertion begin' and 'Insertion end'.](b10763be31553f31cbb795653b731a43_img.jpg)
+
+The diagram illustrates the structure of a DPI signalling stream within a Program 1. The program consists of four PIDs: PMT (PID 1), Video (PID 2), Audio (PID 3), and DVB-SAD (PID 4). The DVB-SAD stream is shown as a sequence of segments over time. Key events are marked: 'SAD Timeline descriptor' (yellow), 'L0 Trigger SAD stream event' (red), and 'L1 Trigger pair SAD stream event' (green). Vertical lines indicate 'Insertion begin' and 'Insertion end'.
+
+| Program   | Component | PID   |
+|-----------|-----------|-------|
+| Program 1 | PMT       | PID 1 |
+|           | Video     | PID 2 |
+|           | Audio     | PID 3 |
+|           | DVB-SAD   | PID 4 |
+
+Timeline markers: Insertion begin, Insertion end, Time.
+
+Event markers: SAD Timeline descriptor, L0 Trigger SAD stream event, L1 Trigger pair SAD stream event.
+
+Reference: J.215(07)\_F02
+
+Figure 2 – DPI signalling stream. A diagram showing a Program 1 with four PIDs: PMT (PID 1), Video (PID 2), Audio (PID 3), and DVB-SAD (PID 4). The DVB-SAD stream is shown as a sequence of segments over time. Key events are marked: 'SAD Timeline descriptor' (yellow), 'L0 Trigger SAD stream event' (red), and 'L1 Trigger pair SAD stream event' (green). Vertical lines indicate 'Insertion begin' and 'Insertion end'.
+
+Figure 2 – DPI signalling stream
+
+Figure 2 illustrates a hypothetical MPEG-2 program stream containing DPI signalling. The DVB-SAD PID contains a series of timeline descriptors, and examples of L0 and L1 triggers. The details of these descriptors and their placement are provided below.
+
+### 7.1.1 DPI Signalling descriptor
+
+The `dpi_signaling_descriptor` is defined for use in the elementary stream information loop of the PMT. This descriptor indicates that the associated elementary stream contains a DPI signalling stream, containing DPI triggers and timeline messages as defined below. Only one elementary stream signalled by the PMT SHALL contain a `dpi_signaling_descriptor`. In the event that more than one PMT entry contains a `dpi_signaling_descriptor`, the implementation SHALL ignore all but the first instance listed in the PMT's elementary stream information loop.
+
+A PMT entry with a `dpi_signaling_descriptor` MAY be associated with a `stream_type` of 0xC0 or 0x05.
+
+The `dpi_signaling_descriptor` is defined in Table 1.
+
+**Table 1 – DPI signalling descriptor syntax**
+
+| Syntax                                    | Bits | Mnemonic            |
+|-------------------------------------------|------|---------------------|
+| <code>dpi_signaling_descriptor() {</code> |      |                     |
+| <code>descriptor_tag</code>               | 8    | <code>uimsbf</code> |
+| <code>descriptor_length</code>            | 8    | <code>uimsbf</code> |
+| <code>For (i=0; i&lt;n; i++) {</code>     |      |                     |
+| <code>private_use</code>                  | 8    | <code>bs1bf</code>  |
+| <code>}</code>                            |      |                     |
+| <code>}</code>                            |      |                     |
+
+**descriptor\_tag** This 8-bit integer with value 0xA2 identifies this descriptor.
+
+**descriptor\_length** This 8-bit integer indicates the number of bytes following the descriptor length field.
+
+**private\_use** This field MAY be used to carry private data to a receiver which interprets this signalling stream. Its use is not defined by this Recommendation.
+
+### 7.1.2 DPI triggers
+
+The format for DPI triggers SHALL be the DVB-SAD synchronized event descriptor, see section 5.2.5 of [DVB-SAD]. When present in a content or insertion feed, the implementation SHALL process every instance of a DVB-SAD synchronized event descriptor.
+
+The use of DPI triggers is different for L0 and L1 switches. To signal an L0 switch, a single DPI trigger MAY be used to indicate the point in a stream at which the switch may occur. For L1 switches, a DPI trigger SHALL be present for each component that will be switched; typically, one for video and one for audio. For L1 switches, a set of DPI triggers SHALL be used to signal a single switch operation.
+
+The following semantics are defined for the DVB-SAD synchronized event descriptor (section 5.2.5 of [DVB-SAD]):
+
+**synchronized\_event\_context**: This field SHALL be encoded according to Table 2. If this field contains a value not defined below, the implementation SHALL ignore this descriptor.
+
+**Table 2 – synchronized\_event\_context**
+
+| Value | Description |
+|-------|-------------|
+| 10    | L1 video    |
+| 11    | L1 audio    |
+| 12    | L0          |
+
+**synchronized\_event\_id:** This field identifies a switch operation. The implementation SHALL use this value to associate a switch instruction with this trigger, if such an instruction has been received from an application.
+
+**synchronized\_event\_data\_byte:** This field SHALL be encoded according to Table 3. If this field is not conformant to Table 3, the implementation SHALL ignore this descriptor.
+
+**Table 3 – synchronized\_event\_data\_byte**
+
+| Syntax          | No. of bits | Identifier |
+|-----------------|-------------|------------|
+| set_size        | 8           | uimsbf     |
+| position_in_set | 8           | uimsbf     |
+
+**set\_size:** This field indicates the number of triggers signalling a switch. For an L0 switch, this value is 1, for an L1 switch, this value is at least 1 and is typically 2; one for video, one for audio.
+
+**position\_in\_set:** This field indicates the position of this trigger within a set of triggers, zero based.
+
+DPI triggers for L0 switches SHALL be present in a stream at a point TBD.
+
+DPI triggers for L1 switches SHALL be present in a stream at a point TBD. For more details on the structure of an L1 conditioned stream, see [DVB-SAD].
+
+### 7.1.3 DPI timelines
+
+A content segment MAY contain timeline messages that allow the implementation to maintain a timeline synchronized to the video and audio content. Timeline messages SHALL be in the DVB-SAD broadcast timeline descriptor format, see [DVB-SAD] clause 5.2.2 for a description of the broadcast timeline descriptor. When present within a content feed, the implementation SHALL process every instance of a DVB-SAD broadcast timeline descriptor to maintain an interpolated metadata timeline. [DVB-SAD] contains descriptions and references to definitions of timelines within several clauses. The reader should be familiar with [DVB-SAD] in its entirety.
+
+L0 switch operations MAY be performed when a point on a timeline is reached. In order to enable time-based switch scenarios in which a viewer may tune away, then tune back into a service during a switch opportunity, streams MAY contain a series of DPI timeline messages throughout the original program.
+
+Within a content feed that signals a timeline and supports L0 switches, a DPI timeline SHALL be continuous throughout the relevant segment. The associated insertion feeds SHALL signal a timeline that is proceeding at the same rate with the same values as the original feed.
+
+Within a content feed that signals a timeline and supporting L1 switches, the DPI signalling stream SHALL contain a continuously advancing timeline.
+
+The following semantics are defined for the DVB-SAD synchronized event descriptor:
+
+Where broadcast\_timeline\_type equals 0:
+
+**tick\_format:** This field SHALL have the value 0x11. See Table 6 of [DVB-SAD].
+
+## 7.2 Switch engine behaviour
+
+Switches may be trigger-based or time-based. A switch instruction MAY identify a set of triggers, and or identify a segment of time during which a switch may occur. A switch is either from an original program feed to an insertion feed, from an insertion feed to another insertion feed, or from an insertion feed back to the original feed. The switch engine SHALL maintain context such that the original feed may be presented in error cases or as default behaviour when the final insertion within a group is completed.
+
+On receipt of a DPI trigger, the implementation SHALL determine whether there is a switch instruction matching the trigger. To match a switch instruction with a trigger, the implementation SHALL determine whether there is a SwitchInstruction with the switchID attribute equal to the value in the synchronized\_event\_id field of the trigger.
+
+Insertions are often made in groups, as is the case when several ad spots make up an ad break. A switch instruction MAY indicate that if a previous insertion within a group is not made, then subsequent insertions should not take place, as might be the case if a service is selected after the first spot in an ad break. An instruction indicates that the entire group must be inserted when the insertionIndivisible attribute is non-zero, and indicates its position within a group via the groupSize and positionInGroup attributes. Where a matched instruction's insertionIndivisible attribute is non-zero, and all previous instructions within its group have not caused a switch, the implementation SHALL not perform a switch. Requirements defined below for performing switches assume this behaviour and do not repeat these statements.
+
+Where an instruction matches a trigger:
+
+- Where the value in the synchronized\_event\_context field of the trigger indicates an L0 trigger, the implementation SHALL perform an L0 switch.
+- Where the value in the synchronized\_event\_context field of the trigger indicates an L1 operation, the implementation SHALL perform an L1 switch.
+
+For time-based switches, the implementation will process DPI timeline messages if present and maintain a metadata timeline for the current service. See clause 7.1.3 for details. When the point on the metadata timeline is reached that is equal to or greater than the value of the switchStartTime (if non-zero) of any switch instruction for the service, and the triggerSwitch flag of the switch instruction is zero, the implementation SHALL perform an L0 switch.
+
+### 7.2.1 Requirements to perform an L0 switch
+
+The implementation SHALL present the program specified by the switch instruction destination field or by the default rules defined for the end of an insertion. Note that an L0 DPI switch is not a service selection, that is, an L0 switch does not affect the lifecycle of any applications associated with the selected service of the original channel, while it may cause the loading and launching of applications associated with the newly presenting program.
+
+### 7.2.2 Requirements to perform an L1 switch
+
+L1 switches are signalled by a set of DPI triggers, one for each component that will be replaced, i.e., one for video, one for audio, etc. L1 triggers are identified as such by the synchronized\_event\_context field of the trigger, see clause 7.1.2.
+
+When an L1 video trigger matching a switch instruction is received, the implementation SHALL discontinue processing the video component of the currently presenting program and begin processing the video component of the program indicated by the destination field of the instruction.
+
+When an L1 audio trigger matching a switch instruction is received, the implementation SHALL discontinue processing the audio component of the currently presenting program and begin processing the first audio component indicated in the PMT of the program indicated by the
+
+destination field of the instruction, or the audio component indicated by the instructions audioChannel attribute if non-zero.
+
+The latency between discontinuation of processing an original component and processing a destination component SHALL NOT be less than one millisecond and SHALL NOT exceed 30 milliseconds.
+
+When a set of video and audio triggers has been processed, the implementation SHALL process all data streams associated with the destination program. This is for the purpose of launching applications that may be associated with the destination program. Note that the destination program may be the original program in the case where the switch is from an insertion feed back to the original feed.
+
+### 7.2.3 Selecting a DPI enabled program
+
+The following requirements for maintaining timelines and performing time-based switches when a service is selected are to accommodate scenarios in which a viewer tunes away from a program and tunes back during an insertion opportunity.
+
+Where a metadata timeline has been established for a service, see clause 7.1.3, the implementation SHALL maintain the timeline if there is an instruction for the service with non-zero values for switchStartTime and switchEndTime and another service is selected. If a third service is selected, the implementation MAY discontinue maintaining the timeline for the original service. If the original service is not re-selected within an hour, the implementation MAY discontinue maintaining the timeline.
+
+If a service is selected and its timeline is active, and the value of the timeline is greater than or equal to the switchStartTime and less than or equal to the switchWindowEndTime, the implementation SHALL perform an L0 switch; an exception to this requirement is where switchWindowEndTime is within four seconds of the switchEndTime: the implementation SHALL not perform an L0 switch within four seconds of the switchEndTime.
+
+### 7.2.4 Switch engine events
+
+If a trigger is encountered and there is no corresponding instruction, an UNARMED\_TRIGGER event SHALL be propagated to any listening targeting engine. If an insertion feed is currently being presented, the switch engine SHALL revert to presenting the original feed.
+
+Where a switch occurs, an INSERTION\_START event SHALL be propagated to any listening targeting engine.
+
+If a viewer selects a DPI enabled service at a point between triggers within a set of L1 triggers, the receiver will not receive all of the triggers within the set, and therefore SHALL NOT perform a switch. Specifically, if the position\_in\_set field of a trigger is greater than or equal to two and a trigger has not been received on the service with position\_in\_set equal to 1, all triggers within the set SHALL be ignored. If not already presenting the original program, the implementation SHALL switch back to the original program and a MISSED\_TRIGGER event SHALL be propagated to any listening targeting engine.
+
+When a switch instruction expires (see Annex A), an INSTRUCTION\_EXPIRED event SHALL be propagated to any targeting engine, and the instruction SHALL be considered inactive.
+
+## 7.3 Switch Engine API
+
+This clause describes the functionality of an application programming interface to a switch engine. This description is provided in 'C' syntax, and can be adapted and implemented in any programming language.
+
+|                             |                                                 |
+|-----------------------------|-------------------------------------------------|
+| <b>SwitchEngineListener</b> | Represents a listener for Switch Engine events. |
+|-----------------------------|-------------------------------------------------|
+
+| Method Summary |                                                                                                                                                                                                                                                          |
+|----------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| void           | <b>notifySwitchEngineEvent</b> (SwitchInstruction SwitchInstruction, int Reason)<br>Method called by the Switch Engine implementation when a Switch Engine event occurs, if the Targeting Engine application has registered as a listener for the event. |
+
+|                            |                                                                                   |
+|----------------------------|-----------------------------------------------------------------------------------|
+| <b>SwitchEngineManager</b> | An application may use this object to control the behaviour of the switch engine. |
+|----------------------------|-----------------------------------------------------------------------------------|
+
+| Method Summary               |                                                                                                                                                                             |
+|------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| abstract void                | <b>addInstruction</b> (SwitchInstruction[] switchInstructions)<br>Add SwitchInstruction(s) to the Switch Engine active list.                                                |
+| static SwitchEngineManager   | <b>getInstance()</b><br>gets the singleton instance of the Switch Engine manager for use by a privileged application.                                                       |
+| abstract SwitchInstruction[] | <b>getInstruction</b> (int[] SwitchIDs, int SourceID)<br>The Switch Engine SHALL return the Switch Instruction(s) matching the passed in SwitchID and SourceID.             |
+| abstract void                | <b>removeInstruction</b> (SwitchInstruction[] switchInstructions)<br>The Switch Engine SHALL remove the passed in Switch Instruction(s) from the Switch Engine active list. |
+| abstract void                | <b>removeSwitchEngineListener</b> (SwitchEngineListener Listener)<br>Removes the previously added SwitchEngineListener.                                                     |
+| abstract void                | <b>setSwitchEngineListener</b> (SwitchEngineListener Listener, byte[] Filter)<br>Adds the listener for Switch Engine events.                                                |
+
+|                          |                                                                                                             |
+|--------------------------|-------------------------------------------------------------------------------------------------------------|
+| <b>SwitchInstruction</b> | A SwitchInstruction encapsulates the information needed by the switch engine to perform a switch operation. |
+|--------------------------|-------------------------------------------------------------------------------------------------------------|
+
+| Constructor Summary                                                                                                                                                                                                                                                                                                     |                                |
+|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------|
+| <b>SwitchInstruction()</b>                                                                                                                                                                                                                                                                                              | SwitchInstruction constructor. |
+| <b>SwitchInstruction</b> (int SourceID, javax.tv.locator.Locator[] Locator, int SwitchID, byte GroupSize, byte PositionInGroup, int SwitchStartTime, int SwitchEndTime, int SwitchWindowEndTime, int ExpirationTime, boolean TriggerSwitch, int InsertionOptions, boolean InsertionIndivisible, boolean EndOfInsertion) | SwitchInstruction constructor. |
+
+| Method Summary             |         |                                                                                                                       |
+|----------------------------|---------|-----------------------------------------------------------------------------------------------------------------------|
+|                            | byte[]  | <b>getEndOfInsertion()</b><br>Retrieve the attribute EndOfInsertion.                                                  |
+|                            | int     | <b>getExpirationTime()</b><br>Retrieve the attribute ExpirationTime.                                                  |
+|                            | byte    | <b>getGroupSize()</b><br>Retrieve the attribute GroupSize.                                                            |
+|                            | boolean | <b>getInsertionIndivisible()</b><br>Retrieve the attribute InsertionIndivisible.                                      |
+|                            | int     | <b>getInsertionOptions()</b><br>Retrieve the attribute InsertionOptions.                                              |
+| javax.tv.locator.Locator[] |         | <b>getLocator()</b><br>Retrieve the attribute Locator.                                                                |
+|                            | byte    | <b>getPositionInGroup()</b><br>Retrieve the attribute PositionInGroup.                                                |
+|                            | int     | <b>getSourceID()</b><br>Retrieve the attribute SourceID.                                                              |
+|                            | int     | <b>getSwitchEndTime()</b><br>Retrieve the attribute SwitchEndTime.                                                    |
+|                            | int     | <b>getSwitchID()</b><br>Retrieve the attribute SwitchID.                                                              |
+|                            | int     | <b>getSwitchStartTime()</b><br>Retrieve the attribute SwitchStartTime.                                                |
+|                            | int     | <b>getSwitchWindowEndTime()</b><br>Retrieve the attribute SwitchWindowEndTime.                                        |
+|                            | boolean | <b>getTriggerSwitch()</b><br>Get attribute TriggerSwitch.                                                             |
+|                            | void    | <b>setEndOfInsertion</b> (boolean EndOfInsertion)<br>Set attribute EndOfInsertion to specified parameter.             |
+|                            | void    | <b>setExpirationTime</b> (int ExpirationTime)<br>Set attribute ExpirationTime to specified parameter.                 |
+|                            | void    | <b>setGroupSize</b> (byte GroupSize)<br>Set attribute GroupSize to specified parameter.                               |
+|                            | void    | <b>setInsertionIndivisible</b> (boolean InsertionIndivisible)<br>Set attribute InsertionIndivisible to True or False. |
+|                            | void    | <b>setInsertionOptions</b> (int InsertionOptions)<br>Set attribute InsertionOptions to specified parameter.           |
+|                            | void    | <b>setLocator</b> (javax.tv.locator.Locator[] Locator)<br>Set attribute Locator to specified parameter.               |
+|                            | void    | <b>setPositionInGroup</b> (byte PositionInGroup)<br>Set attribute PositionInGroup to specified parameter.             |
+|                            | void    | <b>setSourceID</b> (int SourceID)<br>Set attribute SourceID to specified parameter.                                   |
+|                            | void    | <b>setSwitchEndTime</b> (int SwitchEndTime)<br>Set attribute SwitchEndTime to specified parameter.                    |
+|                            | void    | <b>setSwitchID</b> (int SwitchID)<br>Set attribute SwitchID to specified parameter.                                   |
+|                            | void    | <b>setSwitchStartTime</b> (int SwitchStartTime)<br>Set attribute SwitchStartTime to specified parameter.              |
+|                            | void    | <b>setSwitchWindowEndTime</b> (int SwitchWindowEndTime)<br>Set attribute SwitchWindowEndTime to specified parameter.  |
+|                            | void    | <b>setTriggerSwitch</b> (boolean TriggerSwitch)<br>Set attribute TriggerSwitch.                                       |
+
+|                              |                                                                                       |
+|------------------------------|---------------------------------------------------------------------------------------|
+| <b>SwitchEngineException</b> | Allows an exception to pass back the SwitchInstruction associated with the Exception. |
+|------------------------------|---------------------------------------------------------------------------------------|
+
+### | | |----------------------------| | <b>Constructor Summary</b> | |----------------------------|
+
+|                                      |  |
+|--------------------------------------|--|
+| <code>SwitchEngineException()</code> |  |
+|--------------------------------------|--|
+
+### | | |-----------------------| | <b>Method Summary</b> | |-----------------------|
+
+|                                  |                                                                                                    |
+|----------------------------------|----------------------------------------------------------------------------------------------------|
+| <code>SwitchInstruction[]</code> | <b>SwitchInstructionException()</b><br>Returns the SwitchInstruction(s) that caused the exception. |
+|----------------------------------|----------------------------------------------------------------------------------------------------|
+
+# Annex A
+
+## OCAP 1.1 Digital Program Insertion API
+
+(This annex forms an integral part of this Recommendation)
+
+This annex defines a Java application programming interface (API) for application command and control of device DPI functionality.
+
+### Package org.ocap.dpi
+
+- A.1 SwitchEngineException class
+- A.2 SwitchEngineListener Interface
+- A.3 SwitchEngineManager Class
+- A.4 SwitchInstruction Class
+
+### Package org.ocap.dpi
+
+| Interface Summary           |                                                            |
+|-----------------------------|------------------------------------------------------------|
+| <b>SwitchEngineListener</b> | This class represents a listener for Switch Engine events. |
+
+| Class Summary              |                                                                                                             |
+|----------------------------|-------------------------------------------------------------------------------------------------------------|
+| <b>SwitchEngineManager</b> | An application may use this class to control the behaviour of the switch engine.                            |
+| <b>SwitchInstruction</b>   | A SwitchInstruction encapsulates the information needed by the switch engine to perform a switch operation. |
+
+| Exception Summary            |                                                                                                                  |
+|------------------------------|------------------------------------------------------------------------------------------------------------------|
+| <b>SwitchEngineException</b> | Derived from Exception and allows an exception to pass back the SwitchInstruction associated with the Exception. |
+
+### A.1 SwitchEngineException class
+
+###### org.ocap.dpi
+
+#### Class SwitchEngineException
+
+```
+java.lang.Object
+└ java.lang.Throwable
+    └ java.lang.Exception
+        └ org.ocap.dpi.SwitchEngineException
+```
+
+#### All Implemented Interfaces:
+
+```
+java.io.Serializable
+```
+
+```
+public class SwitchEngineException
+extends java.lang.Exception
+```
+
+Derived from Exception and allows an exception to pass back the SwitchInstruction associated with the Exception.
+
+#### Constructor Summary
+
+**SwitchEngineException()**
+
+#### Method Summary
+
+|                     |                                                                                                    |
+|---------------------|----------------------------------------------------------------------------------------------------|
+| SwitchInstruction[] | <b>SwitchInstructionException()</b><br>Returns the SwitchInstruction(s) that caused the exception. |
+|---------------------|----------------------------------------------------------------------------------------------------|
+
+#### Methods inherited from class java.lang.Throwable
+
+fillInStackTrace, getCause, getLocalizedMessage, getMessage, getStackTrace, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString
+
+#### Methods inherited from class java.lang.Object
+
+equals, getClass, hashCode, notify, notifyAll, wait, wait, wait
+
+#### Constructor Detail
+
+#### SwitchEngineException
+
+```
+public SwitchEngineException()
+```
+
+#### Method Detail
+
+#### SwitchInstructionException
+
+```
+public SwitchInstruction[] SwitchInstructionException()
+```
+
+Returns the SwitchInstruction(s) that caused the exception.
+
+##### Returns:
+
+SwitchInstruction[] SwitchInstruction(s) that caused the Exception to be thrown.
+
+### A.2 SwitchEngineListener interface
+
+**org.ocap.dpi**
+
+**Interface SwitchEngineListener**
+
+#### All Superinterfaces:
+
+java.util.EventListener
+
+```
+public interface SwitchEngineListener
+extends java.util.EventListener
+```
+
+This class represents a listener for Switch Engine events.
+
+| Field Summary |                                                                                                                                                                                  |
+|---------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| static int    | <b>COMPONENT_START</b><br>For an L1 Switch a component switch has been completed.                                                                                                |
+| static int    | <b>INSERTION_START</b><br>Switch Instruction was successfully executed and an insertion was accomplished.                                                                        |
+| static int    | <b>INSTRUCTION_EXPIRED</b><br>Switch Instruction was removed because it has passed its valid time based on its ExpirationTime.                                                   |
+| static int    | <b>MISSED_TRIGGER</b><br>The Trigger is position_in_set = 2 or greater and the Switch Instruction's trigger with position_in_set = 1 has not been processed for this Switch set. |
+| static int    | <b>NO_TARGET</b><br>No target for insertion was found at the Locator included in the SwitchInstruction.                                                                          |
+| static int    | <b>UNARMED_TRIGGER</b><br>A Trigger was detected but no matching SwitchInstruction was found.                                                                                    |
+
+| Method Summary |                                                                                                                                                                                                                                                             |
+|----------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| void           | <b>notifySwitchEngineEvent</b> (SwitchInstruction SwitchInstruction,<br>int Reason)<br>Method called by the Switch Engine implementation when a Switch Engine event occurs, if the Targeting Engine application has registered as a listener for the event. |
+
+| Field Detail |  |
+|--------------|--|
+|--------------|--|
+
+#### UNARMED\_TRIGGER
+
+```
+static final int UNARMED_TRIGGER
+```
+
+A Trigger was detected but no matching SwitchInstruction was found.
+
+#### MISSED\_TRIGGER
+
+```
+static final int MISSED_TRIGGER
+```
+
+The Trigger is position\_in\_set = 2 or greater and the Switch Instruction's trigger with position\_in\_set = 1 has not been processed for this Switch set.
+
+#### NO\_TARGET
+
+```
+static final int NO_TARGET
+```
+
+No target for insertion was found at the Locator included in the SwitchInstruction.
+
+#### INSTRUCTION\_EXPIRED
+
+static final int INSTRUCTION\_EXPIRED
+
+Switch Instruction was removed because it has passed its valid time based on its ExpirationTime. This may not be an error if it is for a different source than has been tuned during the Insertion Group.
+
+#### INSERTION\_START
+
+static final int INSERTION\_START
+
+Switch Instruction was successfully executed and an insertion was accomplished.
+
+#### COMPONENT\_START
+
+static final int COMPONENT\_START
+
+For an L1 Switch a component switch has been completed.
+
+#### Method Detail
+
+#### notifySwitchEngineEvent
+
+void notifySwitchEngineEvent(SwitchInstruction SwitchInstruction,  
+int Reason)
+
+Method called by the Switch Engine implementation when a Switch Engine event occurs, if the Targeting Engine application has registered as a listener for the event.
+
+##### Parameters:
+
+SwitchInstruction – The SwitchInstruction that is associated with this Switch Engine event.
+
+Reason – The reason for the event notification.
+
+- UNARMED\_TRIGGER – A Trigger was detected but no matching SwitchInstruction was found.
+- MISSED\_TRIGGER – The Trigger is position\_in\_set = 2 or greater and the trigger where position\_in\_set = 1, has not been processed for this Switch Group.
+- NO\_TARGET – No target for insertion was found at the Locator(s) included in the SwitchInstruction.
+- INSTRUCTION\_EXPIRED – Switch Instruction was removed because it has passed its valid time based on its ExpirationTime.
+- INSERTION\_START – Switch has been accomplished.
+- COMPONENT\_START – For an L1 Switch, a component switch has been completed.
+
+### A.3 SwitchEngineManager Class
+
+###### org.ocap.dpi
+
+#### Class SwitchEngineManager
+
+java.lang.Object
+
+└ org.ocap.dpi.SwitchEngineManager
+
+```
+public abstract class SwitchEngineManager  
+extends java.lang.Object
+```
+
+An application may use this class to control the behaviour of the switch engine.
+
+| Method Summary                  |                                                                                  |                                                                                                        |
+|---------------------------------|----------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------|
+| abstract void                   | <b>addInstruction</b> (SwitchInstruction[]<br>switchInstructions)                | Add SwitchInstruction(s) to the Switch Engine active list.                                             |
+| static SwitchEngineManager      | <b>getInstance()</b>                                                             | gets the singleton instance of the Switch Engine manager for use by a privileged application.          |
+| abstract<br>SwitchInstruction[] | <b>getInstruction</b> (int[] SwitchIDs, int SourceID)                            | The Switch Engine SHALL return the Switch Instruction(s) matching the passed in SwitchID and SourceID. |
+| abstract void                   | <b>removeInstruction</b> (SwitchInstruction[]<br>switchInstructions)             | The Switch Engine SHALL remove the passed in Switch Instruction(s) from the Switch Engine active list. |
+| abstract void                   | <b>removeSwitchEngineListener</b> (SwitchEngineListener<br>Listener)             | Removes the previously added SwitchEngineListener.                                                     |
+| abstract void                   | <b>setSwitchEngineListener</b> (SwitchEngineListener<br>Listener, byte[] Filter) | Adds the listener for Switch Engine events.                                                            |
+
+#### Methods inherited from class java.lang.Object
+
+equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
+
+#### Method Detail
+
+##### getInstance
+
+```
+public static SwitchEngineManager getInstance()
+```
+
+Gets the singleton instance of the Switch Engine manager for use by a privileged application.
+
+##### Throws:
+
+java.lang.SecurityException – if the calling application does not have MonitorAppPermission("dpi").
+
+#### **setSwitchEngineListener**
+
+```
+public abstract void setSwitchEngineListener(SwitchEngineListener Listener,  
+                                                byte[] Filter)
+```
+
+Adds the listener for Switch Engine events.
+
+##### **Parameters:**
+
+**Listener** – Is an instance of a SwitchEngineListener whose SwitchEngineListener method SHALL be called when a Switch Engine event occurs.
+
+**Filter** – A byte array of filters enabling any or all of the following Switch Engine events.
+
+- UNARMED\_TRIGGER
+- MISSED\_TRIGGER
+- NO\_TARGET
+- INSTRUCTION\_EXPIRED
+- INSERTION\_START
+- COMPONENT\_START
+
+##### **Throws:**
+
+java.lang.IllegalArgumentException – Listener is null.
+
+##### **removeSwitchEngineListener**
+
+```
+public abstract void removeSwitchEngineListener(SwitchEngineListener Listener)
+```
+
+Removes the previously added SwitchEngineListener.
+
+##### **Parameters:**
+
+**Listener** – is the Switch Engine Listener to disable. Does nothing if it was never added, has been removed, or is null.
+
+#### **addInstruction**
+
+```
+public abstract void addInstruction(SwitchInstruction[] switchInstructions)
+```
+
+Add SwitchInstruction(s) to the Switch Engine active list.
+
+If TriggerSwitch is FALSE the Switch Engine SHALL perform an L0 Switch when time is at or past the SwitchStartTime in the SwitchInstruction. For all other SwitchInstructions, the Switch Engine SHALL store the Switch Instruction(s) in its active list. For any Switch Instruction that have an identical SwitchID and SourceID to an already existing Switch Instruction, the Switch Engine SHALL replace the Switch Instruction and a Duplicate Switch Instruction Exception is thrown.
+
+##### **Parameters:**
+
+**switchInstructions** –
+
+##### **Throws:**
+
+java.lang.SecurityException – Calling application does not have MonitorAppPermission("dpi")
+
+java.lang.IllegalArgumentException – If the BreakID and SourceID do not identify a SwitchInstruction.
+
+java.lang.IllegalArgumentException – Negative SourceID
+
+
+
+```
+java.lang.SecurityException - Calling application does not have
+MonitorAppPermission("dpi")
+```
+
+### A.4 SwitchInstruction Class
+
+###### org.ocap.dpi
+
+#### Class SwitchInstruction
+
+```
+java.lang.Object
+└ org.ocap.dpi.SwitchInstruction
+```
+
+```
+public class SwitchInstruction
+extends java.lang.Object
+```
+
+A SwitchInstruction encapsulates the information needed by the switch engine to perform a switch operation. A switch operation is performed according to the SwitchInstruction on receipt of a DPI trigger or when a point on a metadata timeline is reached.
+
+Switches may be trigger-based or time-based. A SwitchInstruction MAY identify a set of triggers, and/or identify a segment of time during which a switch may occur.
+
+A SwitchInstruction object MAY be instantiated by a targeting engine application and passed to the implementation via SwitchEngineManager.addInstruction().
+
+For the attributes of the SwitchInstruction, see the SwitchInstruction constructor parameter list.
+
+| Field Summary |                                                                                                          |
+|---------------|----------------------------------------------------------------------------------------------------------|
+| static int    | <b>GO_TO_BLACK</b><br>Go to black at SwitchEndTime even if insert program is not complete.               |
+| static int    | <b>PLAY_TO_COMPLETION</b><br>Play inserted program to completion under all circumstances.                |
+| static int    | <b>RETURN_TO_PROGRAM</b><br>Return to Program at SwitchEndTime even if inserted content is not complete. |
+
+| Constructor Summary                                                                                                                                                                                                                                                                                                     |                                |
+|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------|
+| <b>SwitchInstruction()</b>                                                                                                                                                                                                                                                                                              | SwitchInstruction constructor. |
+| <b>SwitchInstruction</b> (int SourceID, javax.tv.locator.Locator[] Locator, int SwitchID, byte GroupSize, byte PositionInGroup, int SwitchStartTime, int SwitchEndTime, int SwitchWindowEndTime, int ExpirationTime, boolean TriggerSwitch, int InsertionOptions, boolean InsertionIndivisible, boolean EndOfInsertion) | SwitchInstruction constructor. |
+
+| Method Summary |                                                                      |
+|----------------|----------------------------------------------------------------------|
+| byte[]         | <b>getEndOfInsertion()</b><br>Retrieve the attribute EndOfInsertion. |
+| int            | <b>getExpirationTime()</b><br>Retrieve the attribute ExpirationTime. |
+
+| Method Summary             |         |                                                                                                                       |
+|----------------------------|---------|-----------------------------------------------------------------------------------------------------------------------|
+|                            | byte    | <b>getGroupSize()</b><br>Retrieve the attribute GroupSize.                                                            |
+|                            | boolean | <b>getInsertionIndivisible()</b><br>Retrieve the attribute InsertionIndivisible.                                      |
+|                            | int     | <b>getInsertionOptions()</b><br>Retrieve the attribute InsertionOptions.                                              |
+| javax.tv.locator.Locator[] |         | <b>getLocator()</b><br>Retrieve the attribute Locator.                                                                |
+|                            | byte    | <b>getPositionInGroup()</b><br>Retrieve the attribute PositionInGroup.                                                |
+|                            | int     | <b>getSourceID()</b><br>Retrieve the attribute SourceID.                                                              |
+|                            | int     | <b>getSwitchEndTime()</b><br>Retrieve the attribute SwitchEndTime.                                                    |
+|                            | int     | <b>getSwitchID()</b><br>Retrieve the attribute SwitchID.                                                              |
+|                            | int     | <b>getSwitchStartTime()</b><br>Retrieve the attribute SwitchStartTime.                                                |
+|                            | int     | <b>getSwitchWindowEndTime()</b><br>Retrieve the attribute SwitchWindowEndTime.                                        |
+|                            | boolean | <b>getTriggerSwitch()</b><br>Get attribute TriggerSwitch.                                                             |
+|                            | void    | <b>setEndOfInsertion</b> (boolean EndOfInsertion)<br>Set attribute EndOfInsertion to specified parameter.             |
+|                            | void    | <b>setExpirationTime</b> (int ExpirationTime)<br>Set attribute ExpirationTime to specified parameter.                 |
+|                            | void    | <b>setGroupSize</b> (byte GroupSize)<br>Set attribute GroupSize to specified parameter.                               |
+|                            | void    | <b>setInsertionIndivisible</b> (boolean InsertionIndivisible)<br>Set attribute InsertionIndivisible to True or False. |
+|                            | void    | <b>setInsertionOptions</b> (int InsertionOptions)<br>Set attribute InsertionOptions to specified parameter.           |
+|                            | void    | <b>setLocator</b> (javax.tv.locator.Locator[] Locator)<br>Set attribute Locator to specified parameter.               |
+|                            | void    | <b>setPositionInGroup</b> (byte PositionInGroup)<br>Set attribute PositionInGroup to specified parameter.             |
+|                            | void    | <b>setSourceID</b> (int SourceID)<br>Set attribute SourceID to specified parameter.                                   |
+|                            | void    | <b>setSwitchEndTime</b> (int SwitchEndTime)<br>Set attribute SwitchEndTime to specified parameter.                    |
+|                            | void    | <b>setSwitchID</b> (int SwitchID)<br>Set attribute SwitchID to specified parameter.                                   |
+|                            | void    | <b>setSwitchStartTime</b> (int SwitchStartTime)<br>Set attribute SwitchStartTime to specified parameter.              |
+|                            | void    | <b>setSwitchWindowEndTime</b> (int SwitchWindowEndTime)<br>Set attribute SwitchWindowEndTime to specified parameter.  |
+|                            | void    | <b>setTriggerSwitch</b> (boolean TriggerSwitch)<br>Set attribute TriggerSwitch.                                       |
+
+#### Methods inherited from class java.lang.Object
+
+equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
+
+#### Field Detail
+
+##### **GO\_TO\_BLACK**
+
+```
+public static final int GO_TO_BLACK
+```
+
+Go to black at SwitchEndTime even if insert program is not complete.
+
+##### **RETURN\_TO\_PROGRAM**
+
+```
+public static final int RETURN_TO_PROGRAM
+```
+
+Return to Program at SwitchEndTime even if inserted content is not complete.
+
+##### **PLAY\_TO\_COMPLETION**
+
+```
+public static final int PLAY_TO_COMPLETION
+```
+
+Play inserted program to completion under all circumstances.
+
+#### Constructor Detail
+
+#### **SwitchInstruction**
+
+```
+public SwitchInstruction()
+```
+
+SwitchInstruction constructor. Can be used to Instantiate a SwitchInstruction w/o initializing the attributes.
+
+##### **SwitchInstruction**
+
+```
+public SwitchInstruction(int SourceID,  
+                        javax.tv.locator.Locator[] Locator,  
+                        int SwitchID,  
+                        byte GroupSize,  
+                        byte PositionInGroup,  
+                        int SwitchStartTime,  
+                        int SwitchEndTime,  
+                        int SwitchWindowEndTime,  
+                        int ExpirationTime,  
+                        boolean TriggerSwitch,  
+                        int InsertionOptions,  
+                        boolean InsertionIndivisible,  
+                        boolean EndOfInsertion)
+```
+
+SwitchInstruction constructor. Can be used to initialize all attributes in a SwitchInstruction in place of the set methods.
+
+###### **Parameters:**
+
+SourceID – The source id of the service on which this instruction may cause a switch.
+
+Locator – A Locator that identifies the component or program for insertion.
+
+SwitchID – Switch Identifier. Matches the trigger identifier within a set of DPI triggers (synchronized\_event\_id).
+
+GroupSize – Indicates the number of switches within a related group. A group corresponds to an advertising break, which may contain several ad spots.
+
+PositionInGroup – Indicates the position of this switch within a group of insertions, zero based.
+
+SwitchStartTime – Point on a metadata timeline at which an L0 switch may occur.
+
+SwitchEndTime – Point on a metadata timeline at which the insertion segment is over and the switch engine should present the Primary Service.
+
+SwitchWindowEndTime – Point on a metadata timeline at which an L0 switch may not occur. In the case where the service is selected at a point past the switchTimeStart, this value indicates the point when the switch should no longer occur.
+
+ExpirationTime – The time at which the instruction is no longer valid and SHALL NOT cause a switch to occur. The switch engine MAY remove the instruction at this time. The time is num seconds from receipt by switch engine of instruction.
+
+InsertionIndivisible – If true and the first trigger in an Insertion Group is missed then subsequent triggers in the Group SHALL be ignored. Used in conjunction with the GroupSize and PositionInGroup attributes.
+
+TriggerSwitch – boolean with the following meanings:
+
+- If TRUE – DPI Trigger initiates each switch.
+- If FALSE – Metadata time initiates each switch.
+
+NOTE – If TriggerSwitch = FALSE and time is past the SwitchStartTime when the SwitchInstruction is loaded and executed immediately. This assumes that the switch engine is tuned to a service and has established a valid metadata timeline.
+
+InsertionOptions – Options for insertion of content.
+
+- GO\_TO\_BLACK – Go to black at SwitchEndTime even if insert program is not complete.
+- RETURN\_TO\_PROGRAM – Return to Program at SwitchEndTime even if inserted content is not complete.
+- PLAY\_TO\_COMPLETION – Play inserted program to completion under all circumstances.
+
+EndOfInsertion – Identifies if the Switch Instruction should return to the Primary Service. Locator is a don't care.
+
+###### **Throws:**
+
+java.lang.IllegalArgumentException – Negative SourceID
+
+java.lang.IllegalArgumentException – ExpirationTime passed
+
+java.lang.IllegalArgumentException – Unknown InsertionOptions
+
+java.lang.IllegalArgumentException – SwitchEndTime is before SwitchStartTime
+
+java.lang.IllegalArgumentException – Duplicate SwitchID and SourceID.
+
+InvalidLocator – Locator is invalid
+
+InvalidLocator – Locator is null
+
+InvalidLocator – Locator not found
+
+#### Method Detail
+
+##### **setSwitchID**
+
+`public void setSwitchID(int SwitchID)`
+
+Set attribute SwitchID to specified parameter.
+
+###### **Parameters:**
+
+SwitchID – Switch Identifier.
+
+###### **Throws:**
+
+`java.lang.IllegalStateException` – this method is called when the SwitchInstruction is Active (Has been added with the addInstruction).
+
+##### **getSwitchID**
+
+`public int getSwitchID()`
+
+Retrieve the attribute SwitchID.
+
+###### **Returns:**
+
+SwitchID
+
+##### **setGroupSize**
+
+`public void setGroupSize(byte GroupSize)`
+
+Set attribute GroupSize to specified parameter.
+
+###### **Parameters:**
+
+GroupSize – Number of Switches within a group.
+
+###### **Throws:**
+
+`java.lang.IllegalStateException` – this method is called when the SwitchInstruction is Active (Has been added with the addInstruction).
+
+##### **getGroupSize**
+
+`public byte getGroupSize()`
+
+Retrieve the attribute GroupSize.
+
+###### **Returns:**
+
+GroupSize
+
+##### **setPositionInGroup**
+
+`public void setPositionInGroup(byte PositionInGroup)`
+
+Set attribute PositionInGroup to specified parameter.
+
+###### **Parameters:**
+
+PositionInGroup – Position of Switch within a group.
+
+###### **Throws:**
+
+java.lang.IllegalStateException – this method is called when the SwitchInstruction is Active (Has been added with the addInstruction).
+
+##### **getPositionInGroup**
+
+public byte **getPositionInGroup**()
+
+Retrieve the attribute PositionInGroup.
+
+###### **Returns:**
+
+PositionInGroup
+
+##### **setSourceID**
+
+public void **setSourceID**(int SourceID)
+
+Set attribute SourceID to specified parameter.
+
+###### **Parameters:**
+
+SourceID – source identifier.
+
+###### **Throws:**
+
+java.lang.IllegalStateException – this method is called when the SwitchInstruction is Active (Has been added with the addInstruction).
+
+##### **getSourceID**
+
+public int **getSourceID**()
+
+Retrieve the attribute SourceID.
+
+###### **Returns:**
+
+SourceID
+
+##### **setInsertionIndivisible**
+
+public void **setInsertionIndivisible**(boolean InsertionIndivisible)
+
+Set attribute InsertionIndivisible to True or False.
+
+###### **Parameters:**
+
+InsertionIndivisible – Indicator of whether a partial Insertion Period can be processed.
+
+###### **Throws:**
+
+`java.lang.IllegalStateException` – this method is called when the `SwitchInstruction` is Active (Has been added with the `addInstruction`).
+
+##### **getInsertionIndivisible**
+
+`public boolean getInsertionIndivisible()`
+
+Retrieve the attribute `InsertionIndivisible`.
+
+###### **Returns:**
+
+`InsertionIndivisible`
+
+##### **setTriggerSwitch**
+
+`public void setTriggerSwitch(boolean TriggerSwitch)`
+
+Set attribute `TriggerSwitch`.
+
+###### **Parameters:**
+
+`TriggerSwitch` – `boolean` with the following meanings:
+
+- `TRUE` – DPI Trigger initiated Break
+- `FALSE` – Metadata time initiated Break
+
+###### **Throws:**
+
+`java.lang.IllegalStateException` – this method is called when the `SwitchInstruction` is Active (Has been added with the `addInstruction`).
+
+##### **getTriggerSwitch**
+
+`public boolean getTriggerSwitch()`
+
+Get attribute `TriggerSwitch`.
+
+###### **Returns:**
+
+`TriggerSwitch`
+
+##### **setSwitchStartTime**
+
+`public void setSwitchStartTime(int SwitchStartTime)`
+
+Set attribute `SwitchStartTime` to specified parameter.
+
+###### **Parameters:**
+
+`SwitchStartTime` – Time insertion is to begin.
+
+###### **Throws:**
+
+`java.lang.IllegalStateException` – this method is called when the `SwitchInstruction` is Active (Has been added with the `addInstruction`).
+
+##### **getSwitchStartTime**
+
+`public int getSwitchStartTime()`
+
+Retrieve the attribute `SwitchStartTime`.
+
+###### **Returns:**
+
+`SwitchStartTime`
+
+##### **setSwitchEndTime**
+
+`public void setSwitchEndTime(int SwitchEndTime)`
+
+Set attribute `SwitchEndTime` to specified parameter.
+
+###### **Parameters:**
+
+`SwitchEndTime` – End of Insertion Period
+
+###### **Throws:**
+
+`java.lang.IllegalStateException` – this method is called when the `SwitchInstruction` is Active (Has been added with the `addInstruction`).
+
+##### **getSwitchEndTime**
+
+`public int getSwitchEndTime()`
+
+Retrieve the attribute `SwitchEndTime`.
+
+###### **Returns:**
+
+`SwitchEndTime`
+
+##### **setExpirationTime**
+
+`public void setExpirationTime(int ExpirationTime)`
+
+Set attribute `ExpirationTime` to specified parameter.
+
+###### **Parameters:**
+
+`ExpirationTime` – The time when the `Switch Instruction` is no longer valid for an Insertion and can be removed.
+
+###### **Throws:**
+
+`java.lang.IllegalStateException` – this method is called when the `SwitchInstruction` is Active (Has been added with the `addInstruction`).
+
+##### **getExpirationTime**
+
+`public int getExpirationTime()`
+
+Retrieve the attribute ExpirationTime.
+
+###### **Returns:**
+
+ExpirationTime
+
+##### **setSwitchWindowEndTime**
+
+`public void setSwitchWindowEndTime(int SwitchWindowEndTime)`
+
+Set attribute SwitchWindowEndTime to specified parameter.
+
+###### **Parameters:**
+
+SwitchWindowEndTime – point on a metadata timeline at which an L0 switch may not occur. In the case where the service is selected at a point past the switchStartTime, this value indicates the point when the switch should no longer occur.
+
+###### **Throws:**
+
+`java.lang.IllegalStateException` – this method is called when the SwitchInstruction is Active (Has been added with the addInstruction).
+
+##### **getSwitchWindowEndTime**
+
+`public int getSwitchWindowEndTime()`
+
+Retrieve the attribute SwitchWindowEndTime.
+
+###### **Returns:**
+
+SwitchWindowEndTime
+
+##### **setInsertionOptions**
+
+`public void setInsertionOptions(int InsertionOptions)`
+
+Set attribute InsertionOptions to specified parameter.
+
+###### **Parameters:**
+
+InsertionOptions – Options for insertion of content.
+
+- `GO_TO_BLACK` – Go to BLACK at SwitchEndTime even if insert program is not complete.
+- `RETURN_TO_PROGRAM` – Return to Program at SwitchEndTime even if insert program is not complete.
+- `PLAY_TO_COMPLETION` – Play inserted program to completion under all circumstances.
+
+###### **Throws:**
+
+`java.lang.IllegalStateException` – this method is called when the `SwitchInstruction` is Active (Has been added with the `addInstruction`).
+
+##### **getInsertionOptions**
+
+`public int getInsertionOptions()`
+
+Retrieve the attribute `InsertionOptions`.
+
+###### **Returns:**
+
+`InsertionOptions`
+
+##### **setLocator**
+
+`public void setLocator(javax.tv.locator.Locator[] Locator)`
+
+Set attribute `Locator` to specified parameter.
+
+###### **Parameters:**
+
+`Locator` – Identifies the component or program for insertion. `Locator` pointing to media content to switch to.
+
+###### **Throws:**
+
+`java.lang.IllegalStateException` – this method is called when the `SwitchInstruction` is Active (Has been added with the `addInstruction`).
+
+##### **getLocator**
+
+`public javax.tv.locator.Locator[] getLocator()`
+
+Retrieve the attribute `Locator`.
+
+###### **Returns:**
+
+`javax.tv.locator.Locator[]`
+
+##### **setEndOfInsertion**
+
+`public void setEndOfInsertion(boolean EndOfInsertion)`
+
+Set attribute `EndOfInsertion` to specified parameter.
+
+###### **Parameters:**
+
+`EndOfInsertion` – Identifies this as an end of Insertion Swtich Instruction that returns to the primary service.
+
+###### **Throws:**
+
+`java.lang.IllegalStateException` – this method is called when the `SwitchInstruction` is Active (Has been added with the `addInstruction`).
+
+##### **getEndOfInsertion**
+
+`public byte[] getEndOfInsertion()`
+
+Retrieve the attribute EndOfInsertion.
+
+###### **Returns:**
+
+EndOfInsertion
+
+
+
+
+
+## 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.280**
+
+(03/2013)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Digital transmission of television signals
+
+---
+
+**Digital program insertion: Splicing application  
+program interface**
+
+Recommendation ITU-T J.280
+
+
+
+# Recommendation ITU-T J.280
+
+# Digital program insertion: Splicing application program interface
+
+## Summary
+
+The splicing application program interface (API) focuses on the single server, single splicer configuration. This version of the Recommendation increases the value of Revision\_Num from 1 to 2.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                      |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------------|
+| 1.0     | ITU-T J.280    | 2004-03-15 | 9           | <a href="http://handle.itu.int/11.1002/1000/7204-en">11.1002/1000/7204-en</a>   |
+| 2.0     | ITU-T J.280    | 2005-12-14 | 9           | <a href="http://handle.itu.int/11.1002/1000/8668-en">11.1002/1000/8668-en</a>   |
+| 3.0     | ITU-T J.280    | 2013-03-01 | 9           | <a href="http://handle.itu.int/11.1002/1000/11829-en">11.1002/1000/11829-en</a> |
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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 .....                              | 1  |
+| 3.1  | Terms defined elsewhere .....                  | 1  |
+| 3.2  | Terms defined in this Recommendation.....      | 1  |
+| 4    | Abbreviations and acronyms .....               | 2  |
+| 5    | Conventions .....                              | 3  |
+| 6    | Requirements .....                             | 3  |
+| 6.1  | System block diagram .....                     | 3  |
+| 6.2  | Arbitration priorities.....                    | 5  |
+| 6.3  | Abnormal terminations.....                     | 6  |
+| 6.4  | Splicing requirements.....                     | 7  |
+| 6.5  | Communication .....                            | 7  |
+| 7    | API syntax .....                               | 7  |
+| 7.1  | Splicing_API_Message syntax.....               | 7  |
+| 7.2  | Conventions and requirements .....             | 9  |
+| 7.3  | Initialization.....                            | 10 |
+| 7.4  | Embedded cueing messages .....                 | 11 |
+| 7.5  | Splice messages .....                          | 12 |
+| 7.6  | Alive messages .....                           | 16 |
+| 7.7  | Extended data messages .....                   | 17 |
+| 7.8  | Abort messages.....                            | 18 |
+| 7.9  | Abort_Request message .....                    | 18 |
+| 7.10 | Abort_Response message.....                    | 18 |
+| 7.11 | TearDownFeed_Request message.....              | 18 |
+| 7.12 | TearDownFeed_Response message .....            | 19 |
+| 7.13 | Requesting configuration settings .....        | 19 |
+| 7.14 | General_Response message.....                  | 19 |
+| 8    | Additional structures.....                     | 19 |
+| 8.1  | Version .....                                  | 19 |
+| 8.2  | Hardware_Config .....                          | 20 |
+| 8.3  | splice_elementary_stream( ).....               | 23 |
+| 8.4  | time( ) field definition .....                 | 24 |
+| 8.5  | splice_API_descriptor( ) field definition..... | 25 |
+| 9    | Time synchronization .....                     | 32 |
+| 10   | System timing .....                            | 33 |
+| 10.1 | DPI splice signal flow .....                   | 33 |
+
+|                                                                                                          | <b>Page</b> |
+|----------------------------------------------------------------------------------------------------------|-------------|
+| 10.2 DPI splice initiation timeline.....                                                                 | 34          |
+| Appendix I – Result codes .....                                                                          | 36          |
+| Appendix II – Example use of Logical_Multiplex type 0x0006 and the<br>port_selection_descriptor( ) ..... | 39          |
+| II.1 Informative example 1 .....                                                                         | 39          |
+| II.2 Informative example 2.....                                                                          | 39          |
+| Appendix III – Frame rate codes.....                                                                     | 40          |
+| Bibliography.....                                                                                        | 41          |
+
+# Recommendation ITU-T J.280
+
+## Digital program insertion: Splicing application program interface
+
+# 1 Scope
+
+This application program interface (API) creates a standardized method of communication between servers and splicers for the insertion of content into any MPEG-2 output multiplex in the splicer. This API is flexible enough to support one or more servers attached to one or more splicers. Digital program insertion includes content such as spot advertisements of various lengths, program substitution, public service announcements or program material created by splicing portions of the program from a server.
+
+# 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 H.222.0] Recommendation ITU-T H.222.0 (2012) | ISO/IEC 13818-1:2012, *Information technology – Generic coding of moving pictures and associated audio information: Systems*.
+- [ITU-T H.262] Recommendation ITU-T H.262 (2012) | ISO/IEC 13818-2:2012, *Information technology – Generic coding of moving pictures and associated audio information: Video*.
+- [ANSI/SCTE 35] ANSI/SCTE 35 2012 (2012), *Digital Program Insertion Cueing Message for Cable*.
+- [ANSI/SCTE 54] ANSI/SCTE 54 2009 (2009), *Digital Video Service Multiplex and Transport System Standard for Cable Television*.
+- [ANSI/SCTE 128] ANSI/SCTE 128 2010a (2010), *AVC Video Systems and Transport Constraints for Cable Television*.
+
+# 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+None.
+
+### 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+- 3.2.1 API connection:** A TCP/IP socket connection between a server and a splicer for transferring API messages.
+- 3.2.2 back-to-back insertion:** Insertion of two or more temporally contiguous sessions without returning to the primary channel between sessions.
+- 3.2.3 channel:** A channel is a synonym for a "Service" in DVB terminology, or a "Program" in MPEG terminology.
+
+- 3.2.4 insertion channel:** The insertion multiplex channel(s) that replaces the primary channel in whole or in part of the duration for a splice event.
+- 3.2.5 insertion multiplex:** This is the source of the insertion channel. A multiplex produced by a server may under some circumstances exclude program specific information (PSI), thus it is understood that this multiplex may be a non-compliant MPEG-2 transport stream.
+- 3.2.6 multiplex:** A multiplex is a collection of one or more channel(s) that may include the associated service information. A multiplex is an MPEG-2 transport stream with the possible exception of an insertion multiplex.
+- 3.2.7 output channel:** The channel that is produced at the output of the splicer.
+- 3.2.8 output multiplex:** The MPEG-2 transport stream produced by multiplexing one or more output channels.
+- 3.2.9 primary channel:** The primary multiplex channel that is replaced in whole or in part. A single primary channel may result in multiple output channels.
+- 3.2.10 primary multiplex:** This is the source of the primary channel(s).
+- 3.2.11 server:** The device that originates the insertion channel(s) to be spliced into the primary channel(s). This device communicates with the splicer about when and what to splice.
+- 3.2.12 session:** A session is the insertion of content (such as spot advertisements of various lengths, program substitution, public service announcements, or program material created by splicing portions of the program from a server). Each session is identified by a unique SessionID.
+- 3.2.13 splice-in:** The splice at the start of the insertion. This happens at the time specified in the Splice\_Request message.
+- 3.2.14 splice-out:** The splice at the end of the insertion. The expected insertion end time is calculated by adding the start time and the duration specified in the Splice\_Request message; however, this may occur earlier due to error conditions.
+- 3.2.15 splicer:** The device that splices the insertion channel(s) into the primary channel(s). It may receive ANSI/SCTE 35 cue messages. This device also communicates with the server about when and what to splice.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|         |                                                         |
+|---------|---------------------------------------------------------|
+| API     | Application Program Interface                           |
+| DVB-ASI | Digital Video Broadcast – Asynchronous Serial Interface |
+| ID      | Identifier                                              |
+| MLD     | Multicast Listener Discovery                            |
+| MPEG    | Moving Picture Experts Group                            |
+| MPTS    | Multi-Program Transport Stream                          |
+| NTP     | Network Time Protocol                                   |
+| PAT     | Program Association Table                               |
+| PCR     | Program Clock Reference                                 |
+| PID     | Packet Identifier                                       |
+| PMT     | Program Map Table                                       |
+| PSI     | Program Specific Information                            |
+
+|         |                                                     |
+|---------|-----------------------------------------------------|
+| SPTS    | Single Program Transport Stream                     |
+| tcimsbf | twos complement integer, most significant bit first |
+| TCP/IP  | Transport Control Protocol/Internet Protocol        |
+| uimsbf  | unsigned integer, most significant bit first        |
+| UTC     | Coordinated Universal Time                          |
+
+# 5 Conventions
+
+None.
+
+# 6 Requirements
+
+### 6.1 System block diagram
+
+This API may be used with many different configurations of server(s) and splicer(s). This API focuses on the single server, single splicer configuration shown in Figure 6-1. However, this can be expanded to the multiple servers, multiple splicers configuration as shown in Figure 6-2.
+
+![Figure 6-1 – Single server/Single splicer. A block diagram showing a Splicer unit receiving Primary and Insertion Multiplex inputs, connected to a Server via a Network connection, and producing an Output Multiplex.](dbe553cf16dd14073b89a8263a428664_img.jpg)
+
+The diagram illustrates a 'Splicer' unit (enclosed in a dashed box) that receives two input multiplexes: 'Primary Multiplex (with or without embedded cue message)' and 'Insertion Multiplex'. Inside the splicer, these inputs are processed through 'Primary Channel' and 'Insertion Channel' respectively, which then converge into a 'TCP/IP socket'. The output of the socket is an 'Output Channel' that leads to an 'Output Multiplex'. A 'Server' block is connected to the 'TCP/IP socket' via a 'Network connection' (indicated by a double-headed arrow). The diagram is labeled 'J.280(13)\_F6-1' in the bottom right corner.
+
+Figure 6-1 – Single server/Single splicer. A block diagram showing a Splicer unit receiving Primary and Insertion Multiplex inputs, connected to a Server via a Network connection, and producing an Output Multiplex.
+
+Figure 6-1 – Single server/Single splicer
+
+![Diagram of Multiple servers/Multiple splicers architecture showing Splicer 1 and Splicer (K) connected via a network connection to multiple servers (Server 1 to Server N).](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg)
+
+The diagram illustrates a system architecture for multiple servers and multiple splicers. At the top, **Splicer 1** is shown within a dashed box. It has three input channels: a **Primary Channel** (receiving a **Primary Multiplex (with or without embedded cue message)**), and two **Insertion Channels** (receiving **Insertion Multiplex** signals). The **Primary Channel** and one **Insertion Channel** are connected to an internal switch. The output of this switch is an **Output Channel**, which leads to an **Output Multiplex**. A **TCP/IP socket** within **Splicer 1** is connected via a double-headed arrow to a central **Network connection** block. This network connection block contains a small icon representing a network interface. Below the network connection, another **TCP/IP socket** is connected to the same network connection. This socket is part of **Splicer (K)**, also shown within a dashed box. **Splicer (K)** has three input channels: two **Insertion Channels** (receiving **Insertion Multiplex** signals) and a **Primary Channel** (receiving a **Primary Multiplex (with or without embedded cue message)**). The output of its internal switch is an **Output Channel**, which leads to an **Output Multiplex**. To the left of the splicers, there are **Server 1** and **Server (N)**, each shown within a dashed box. Both servers are connected to the central **Network connection** block. **Server 1** has an arrow pointing to the first **Insertion Multiplex** input of **Splicer 1**. **Server (N)** has an arrow pointing to the second **Insertion Multiplex** input of **Splicer (K)**. The diagram is labeled **J.280(13)\_F6-2** in the bottom right corner.
+
+Diagram of Multiple servers/Multiple splicers architecture showing Splicer 1 and Splicer (K) connected via a network connection to multiple servers (Server 1 to Server N).
+
+**Figure 6-2 – Multiple servers/Multiple splicers**
+
+The model referenced in this API has one or more splicers with one or more multiplex inputs. The splicer logically separates the channel(s) in the multiplex(es) and presents these channel(s) to a switch. This switch is capable of mapping any input to any output channel. The initial configuration maps primary channel(s) to the output channel(s). The server may then direct the splicer to switch from a primary channel to an insertion channel for a specified duration. It may then direct the splicer to switch to another insertion channel following the initial switch. The splicer may then create an MPEG-2 transport stream produced by multiplexing one or more output channels that shall be compliant with [ANSI/SCTE 54].
+
+Logically, a splice involves two input channels and one output channel. The splicer is responsible for joining the various elementary streams (audio, video and data) together. The optimal splice point may occur at slightly different times for each elementary stream, so the splicer should perform the splice that will supply the best quality output. Splicing may not always be performed from the primary channel, i.e., programming network, to the insertion channel, i.e., spot advertisement, and back to the primary channel. The splicer may splice content that is stored solely on the server and arrives over a single input multiplex. It is possible to use this API in a situation where a server has one multi-program transport stream (MPTS) output that contains program and interstitial material and uses the splicer to create proper splices between the content.
+
+This API supports all combinations of single and multiple servers communicating with single and multiple splicers. A separate API connection is associated with each output channel.
+
+In some configurations, there can be either multiple servers or multiple channels within the insertion multiplex connected to a splicer. In these cases, the splicer will have multiple API connections associated with an output channel. When an ANSI/SCTE 35 cueing message is received in a primary channel, the **Cue\_Request** message must be sent to servers over all of the API connections that were made for the associated output channel(s). It is also possible that more than one API connection will transport a **Splice\_Request** message for the same insertion at the same time for an output channel.
+
+### 6.2 Arbitration priorities
+
+Different levels of access are used to ensure that the correct insertion channel is utilized. There are ten different levels of access, 0 to 9, with 9 being the highest priority which may override any lower priority connection. The **OverridePlaying** flag in the **Splice\_Request** message specifies whether an insertion request is honoured when the splicer is currently queueing or performing an insertion. If the flag is set to 1, then the higher priority insertion can interrupt the same or lower priority currently playing insertion. If the flag is set to 0, the splicer will not replace the insertion currently playing, even if the new request is of a higher priority.
+
+The **Splice\_Request** message should be sent at least three seconds before the splice time( ) in order to be valid. If the three-second minimum is not met, the outcome of the **Splice\_Request** message is not determined by this API. If multiple servers initiate splice requests for the same time with the same priority, the splicer will prioritize the requests on a first-come, first-served basis. All other requests will be denied and a collision error will be sent in the **Splice\_Response** message (unless the **OverridePlaying** flag is set).
+
+For example, during the period of time immediately preceding the initiation of an insertion, the following is true: if a priority 5 **Splice\_Request** is received for the same splice time as a priority 3 **Splice\_Request**, a collision error is returned for the priority 3 request. If a priority 7 **Splice\_Request** is later received for the same time, a collision error is returned for the priority 5 request and the priority 7 request is queued. If a second priority 7 request is received with the **OverridePlaying** flag set to 0, then the second priority 7 request would receive a collision error. However, if the **OverridePlaying** flag is set to 1 on the second priority 7 request, the original priority 7 request would receive a collision error and be overridden.
+
+In Figure 6-3, three splicer inputs are shown. The shaded areas indicate which input source will be directed to the output channel at any given moment.
+
+![Figure 6-3 – OverridePlaying flag operation. A timeline diagram showing three input channels (Primary Channel, Insertion Channel 1, and Insertion Channel 2) over time. The Primary Channel is a continuous line with shaded segments. Insertion Channel 1 has a shaded segment from t1 to t2, then a white segment from t2 to t3, then a shaded segment from t3 to t4, and finally a white segment from t4 to t5. Insertion Channel 2 has a shaded segment from t2 to t3, and another shaded segment from t4 to t6. Arrows indicate the flow of signals: from the Primary Channel to Insertion Channel 1 at t1, from Insertion Channel 1 to the Primary Channel at t2, from Insertion Channel 2 to the Primary Channel at t3, from the Primary Channel to Insertion Channel 1 at t4, and from Insertion Channel 1 to the Primary Channel at t5. A horizontal arrow at the bottom right indicates the direction of time.](8e14350b4b669119a3bdfca7869110ca_img.jpg)
+
+The diagram illustrates the arbitration of three input channels over time. The **Primary Channel** is shown as a continuous horizontal line. **Insertion Channel 1 (From Server 1)** and **Insertion Channel 2 (From Server 2)** are shown as horizontal bars above the Primary Channel. Shaded regions indicate active signal segments. Time points  $t1$  through  $t6$  are marked with vertical arrows. At  $t1$ , a signal from the Primary Channel enters Insertion Channel 1. At  $t2$ , a signal from Insertion Channel 1 enters the Primary Channel. At  $t3$ , a signal from Insertion Channel 2 enters the Primary Channel. At  $t4$ , a signal from the Primary Channel enters Insertion Channel 1. At  $t5$ , a signal from Insertion Channel 1 enters the Primary Channel. At  $t6$ , a signal from Insertion Channel 2 enters the Primary Channel. A horizontal arrow at the bottom right is labeled "time".
+
+Figure 6-3 – OverridePlaying flag operation. A timeline diagram showing three input channels (Primary Channel, Insertion Channel 1, and Insertion Channel 2) over time. The Primary Channel is a continuous line with shaded segments. Insertion Channel 1 has a shaded segment from t1 to t2, then a white segment from t2 to t3, then a shaded segment from t3 to t4, and finally a white segment from t4 to t5. Insertion Channel 2 has a shaded segment from t2 to t3, and another shaded segment from t4 to t6. Arrows indicate the flow of signals: from the Primary Channel to Insertion Channel 1 at t1, from Insertion Channel 1 to the Primary Channel at t2, from Insertion Channel 2 to the Primary Channel at t3, from the Primary Channel to Insertion Channel 1 at t4, and from Insertion Channel 1 to the Primary Channel at t5. A horizontal arrow at the bottom right indicates the direction of time.
+
+Figure 6-3 – OverridePlaying flag operation
+
+t1 – Server 1 issues a **Splice\_Request** message and begins its stream to the splicer. The splicer switches this insertion channel stream to the output channel. The **Splice\_Request** has requested an insertion duration from time t1 to time t5. The splicer shall send Server 1 a **SpliceComplete\_Response** message with the **SpliceType** flag set to Splice\_in and a result code set to 100, "Successful Response".
+
+t2 – Server 2 issues a **Splice\_Request**, with the **OverridePlaying** flag set to 1 and has an equal or higher priority. At the time specified by the **Splice\_Request**, Insertion Channel 2's stream is switched to the output channel (replacing the ongoing stream from Server 1). Server 2's **Splice\_Request** requests a duration from time t2 to time t3. The splicer shall send Server 1 a **SpliceComplete\_Response** message with the **SpliceType** flag set to Splice\_out and a result code set to 125, "Channel Override". The splicer shall send Server 2 a **SpliceComplete\_Response** message with the **SpliceType** flag set to Splice\_in and a result code set to 100, "Successful Response". If Server 1 determines that the channel override is an error, it may send an **Abort\_Request** and terminate its stream at this time. This behaviour is not shown in Figure 6-3.
+
+t3 – The insertion duration is completed and the splicer returns to the material from Server 1 to direct to the output channel. Note that the splicer did not return to the primary channel for direction to the output channel. The splicer shall send Server 1 a **SpliceComplete\_Response** message with the **SpliceType** flag set to Splice\_in and a result code set to 125, "Channel Override". The splicer shall send Server 2 a **SpliceComplete\_Response** message with the **SpliceType** flag set to Splice\_out and a result code set to 100, "Successful Response".
+
+t4 – Server 2 issues another **Splice\_Request**, with the **OverridePlaying** flag set to 1. At the time specified by the **Splice\_Request**, Insertion Channel 2's stream is switched to the output channel (replacing the still ongoing stream from Server 1). Server 2's **Splice\_Request** requests a duration from time t4 to time t6. The splicer shall send Server 1 a **SpliceComplete\_Response** message with the **SpliceType** flag set to Splice\_out and a result code set to 125, "Channel Override". The splicer shall send Server 2 a **SpliceComplete\_Response** message with the **SpliceType** flag set to Splice\_in and a result code set to 100, "Successful Response".
+
+t5 – Server 1's insertion stream ends with two portions of its duration having been played and two portions having been overridden by Server 2's stream.
+
+t6 – The final insertion duration is completed and the splicer returns to the material from the primary channel for direction to the output channel. The splicer shall send Server 2 a **SpliceComplete\_Response** message with the **SpliceType** flag set to Splice\_out and a result code set to 100, "Successful Response".
+
+It is also possible that multiple servers will need to split a **Cue\_Request** message; a 60-second duration splicing opportunity where one server will use the first 30 seconds and the second server will use the last 30 seconds, for example. Depending on the priorities and when the **Splice\_Request** messages are received, the splicer shall indicate a result code 109 (Splice Collision) if one exists. This API does not coordinate the ability of the two servers to be able to perform this functionality. This can be done by mutual agreement between the servers or by a server-to-server API.
+
+### 6.3 Abnormal terminations
+
+It is possible that an insertion will be overridden at some time during playback by a higher priority insertion. In this case, the splicer shall return to the overridden insertion at the end of the higher priority insertion. If the higher priority insertion is aborted by an **Abort\_Request** message, the splicer shall return to the overridden insertion. If the initial insertion channel is no longer available, then the splicer shall return to the primary channel if possible.
+
+If the server requests a splice on a primary channel that currently has no valid input, the splicer shall perform the splice and report a result code 111 (No Primary Channel Found) in the **SpliceComplete\_Response** to the server. Likewise, a splice from an insertion channel back to a primary channel that has no valid input shall complete with the result code 111 (No Primary Channel Found).
+
+The splicer vendor may consider adding software to ensure that the splicer always returns to the primary channel. It is highly desirable to have the splicer fail-safe to the primary channel on any error condition that would cause the output channel to stop transmitting.
+
+### 6.4 Splicing requirements
+
+The splicer requires information about the insertion channel before it can be spliced into the primary channel. Some of this information shall be sent in the API connection and some of it may be sent in the MPEG multiplex. All of the information is required before the splice.
+
+**ChannelName** is used for output channel identification. This is a unique name assigned to each output channel (e.g., CNN, Cable News Network) in the splicer set-up and is needed by the server to determine which primary channel shall be replaced by each insertion channel.
+
+The splicer needs to know which insertion channel to splice into the primary channel. This includes the insertion multiplex location and which channel in the insertion multiplex to use. This information is available in the **Splice\_Request** message.
+
+### 6.5 Communication
+
+The communication between the server and the splicer is conducted over one TCP/IP socket connection per output channel. Once this API connection is established it remains established until one of the devices terminates it, at which time re-initialization is required to splice again.
+
+All messages exchanged between the splicer and server share a common general format detailed in clause 7.1. Only messages adhering to this format shall be used for communication between the splicer and server. The format allows for a class of "User Defined" type messages that can be used as a template for private data messages between the server and splicer, but is beyond the scope of this Recommendation.
+
+All request messages require a response from either the splicer or the server, depending on which device is making the request. Most of the response messages only indicate a result and do not contain any other data, but are needed to ensure that the message was received and interpreted correctly by the requester. If there are errors, the message can be resent.
+
+# 7 API syntax
+
+### 7.1 Splicing\_API\_Message syntax
+
+Messages in this API all contain a general message structure that wraps the data for the specific message being sent. This is done so that when the message is received a common parsing routine can store the message, determine what the structure of the data is and ensure that the message is received correctly.
+
+**Table 7-1 – Splicing\_API\_Message**
+
+| Syntax                  | Bytes | Type   |
+|-------------------------|-------|--------|
+| Splicing_API_Message {  |       |        |
+| <b>MessageID</b>        | 2     | uimsbf |
+| <b>MessageSize</b>      | 2     | uimsbf |
+| <b>Result</b>           | 2     | uimsbf |
+| <b>Result_Extension</b> | 2     | uimsbf |
+| data()                  | *     | *      |
+| }                       |       |        |
+
+**MessageID** – An integer value that indicates what message is being sent. See Table 7-2.
+
+**MessageSize** – The size of the data( ) field being sent in bytes.
+
+**Result** – The results to the requested message. See Appendix I for details on the result codes. On request messages, this is set to 0xFFFF.
+
+**Result\_Extension** – This shall be set to 0xFFFF unless used to send additional result information in a response message.
+
+data( ) – Specific data structure for the message being sent. Details on each of the messages containing data are described below. The size of this field is equal to the **MessageSize** and is determined by the size of the data being added to the message. Not all messages utilize the data( ) field.
+
+**Table 7-2 – MessageID values**
+
+| MessageID | Message name            | Sent by           | Description                                                                                                    |
+|-----------|-------------------------|-------------------|----------------------------------------------------------------------------------------------------------------|
+| 0x0000    | General_Response        | Splicer or Server | Used to convey asynchronous information between the devices. There is no data( ) associated with this message. |
+| 0x0001    | Init_Request            | Server            | Initial message to the splicer on port 5168.                                                                   |
+| 0x0002    | Init_Response           | Splicer           | Initial response to the server on the established connection.                                                  |
+| 0x0003    | ExtendedData_Request    | Server            | Request for detailed playback information from the splicer.                                                    |
+| 0x0004    | ExtendedData_Response   | Splicer           | Vendor unique response of extended playback data from the requested playback event.                            |
+| 0x0005    | Alive_Request           | Server            | Sends an alive message to acquire current status.                                                              |
+| 0x0006    | Alive_Response          | Splicer           | Response to the alive message indicating current status.                                                       |
+| 0x0007    | Splice_Request          | Server            | Request to splice at a specific time.                                                                          |
+| 0x0008    | Splice_Response         | Splicer           | Response to indicate that the <b>Splice_Request</b> was received and that the splicer is preparing to splice.  |
+| 0x0009    | SpliceComplete_Response | Splicer           | Response at the splice in and splice out.                                                                      |
+| 0x000A    | GetConfig_Request       | Server            | Request to get the current splice configuration for this API connection.                                       |
+
+**Table 7-2 – MessageID values**
+
+| MessageID               | Message name          | Sent by | Description                                                                                                                        |
+|-------------------------|-----------------------|---------|------------------------------------------------------------------------------------------------------------------------------------|
+| 0x000B                  | GetConfig_Response    | Splicer | Contains all of the splice information for the API connection.                                                                     |
+| 0x000C                  | Cue_Request           | Splicer | Splicer sending the cue info section to the server.                                                                                |
+| 0x000D                  | Cue_Response          | Server  | Acknowledgment that the cue info section was received.                                                                             |
+| 0x000E                  | Abort_Request         | Server  | Request to immediately return to the primary channel or overridden insertion channel.                                              |
+| 0x000F                  | Abort_Response        | Splicer | Acknowledgment that the <b>Abort_Request</b> message was received. A SpliceComplete_Response shall also be generated if necessary. |
+| 0x0010                  | TearDownFeed_Request  | Server  | Request to delete an output channel created using the create_feed_descriptor( ).                                                   |
+| 0x0011                  | TearDownFeed_Response | Splicer | Response to indicate that the output channel has been deleted.                                                                     |
+| 0x0012-0x7FFF<br>0xFFFF | Reserved              |         | Range reserved for future standardization.                                                                                         |
+| 0x8000-0xFFFE           | User defined          |         | Range available for user-defined functions.                                                                                        |
+
+### 7.2 Conventions and requirements
+
+1. Each message that contains data is outlined with its data fields and types below. Additional structures are indicated as functions and are described in clause 8.
+2. All string lengths have space reserved for a null terminator character and must use null terminated strings. For example, a string that is defined as 16 characters can be at most 15 characters of data followed by a null (0x00) character immediately after the last data character. Once a null is encountered in scanning a string, the rest of the characters in the string are undefined. The size defined for the string is constant and will not vary depending on the length of the string. This specification uses 8-bit ASCII characters for strings.
+3. All time values are UTC.
+4. This specification uses all 1s for a DON'T CARE condition. For a 4-byte field, this value would be 0xFFFFFFFF.
+5. Response messages shall be sent out without unnecessary delay. The device expecting a response should consider no response within 5 seconds to indicate a timeout. When a server suspects a timeout, it shall send an Alive\_Request message. If the splicer does not answer as specified in this Recommendation, the connection for this channel shall be dropped and re-established.
+6. A server receiving a response message indicating a failure to parse a message (error code 123) shall send an Alive\_Request message. If it does not receive the appropriate Alive\_Response message, the connection for this channel shall be dropped and re-established.
+7. The Result field in the Splicing\_API\_Message is used to return a result code. Multiple response codes can be returned by sending multiple **General\_Response** messages at any time.
+
+8. If the splicer or server cannot parse the Request message, it shall return a **General\_Response** with the result code 123.
+
+### 7.3 Initialization
+
+The initial communication begins with the splicer listening on the predefined port 5168 and a server opening an API connection to the splicer. The server sends an **Init\_Request** message to the splicer. The server then listens for the response from the splicer on the established API connection. All further communication is done on this API connection. Either the splicer or server may terminate communications by closing this API connection. Each device is responsible for detecting and properly handling a closed API connection. When the splicer initializes the TCP listener on port 5168, it should allow for at least three times the number of insertion channels for API connections to the splicer. For example, if the splicer controls 70 channels of which 40 are "spliceable", then it should allow 120,  $(40 \times 3)$ , simultaneous API connections.
+
+#### 7.3.1 Init\_Request message
+
+The data( ) field for this message contains the Init\_Request\_Data structure outlined below.
+
+**Table 7-3 – Init\_Request\_Data**
+
+| Syntax                                                                                                                                                                                              | Bytes | Type |
+|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|------|
+| Init_Request_Data {<br>Version( )<br><b>ChannelName</b> 32          String<br><b>SplicerName</b> 32          String<br>Hardware_Config( )<br>for (i=0; i<N; i++)<br>splice_API_descriptor(<br>}<br> |       |      |
+
+**Version( )** – See clause 8.1.
+
+**ChannelName** – Logical name given to the output channel of this connection. This is also used to verify the correct API connection when the splicer responds to the server.
+
+**SplicerName** – Name of the splicing device if the server uses the API to communicate to a device that controls multiple splicers.
+
+**Hardware\_Config( )** – See clause 8.2.
+
+**splice\_API\_descriptor( )** – A descriptor that must follow the syntax defined in clause 8.5. The missing\_Primary\_Channel\_action\_descriptor( ) is a suitable descriptor for this request.
+
+#### 7.3.2 Init\_Response message
+
+After the **Init\_Request** is sent, the splicer sends an **Init\_Response** message on the opened API connection. The server verifies that the version sent by the splicer is supported and that it has an API connection to the correct primary channel.
+
+The data( ) field for this message contains the Init\_Response\_Data structure outlined below.
+
+**Table 7-4 – Init\_Response\_Data**
+
+| Syntax                                                        | Bytes | Type   |
+|---------------------------------------------------------------|-------|--------|
+| Init_Response_Data {<br>Version( )<br><b>ChannelName</b><br>} | 32    | String |
+
+Version( ) – See clause 8.1. The splicer shall respond with the highest version number of the API that it is capable of supporting.
+
+**ChannelName** – Returned to the server to indicate the correct connection was made.
+
+### 7.4 Embedded cueing messages
+
+Splicers may have the ability to receive embedded cue messages based upon [ANSI/SCTE 35]. Once these cue messages are received by the splicer, they need to be passed to the server. The **Cue\_Request** message is used to pass these cue messages to the server from the splicer. When a splicer receives a cue message it sends the entire splice\_info\_section( ) along with the splice time to the server. The server will acknowledge the message with a **Cue\_Response** message. The **Cue\_Response** message consists of just the Splicing\_API\_Message and has no associated data( ) but it may have a return code. The splicer will decrypt the splice\_info\_section( ) before sending it to the server if it is encrypted.
+
+If the splicer receives a cue message that has an invalid cyclic redundancy check (CRC), it shall send a **General\_Message** to the server with a result code of 117 (Invalid Cue Message). The splicer shall not send the **Cue\_Request** message in this case.
+
+It is suggested that the splicer be configurable as to which ANSI/SCTE 35 messages generate a Cue\_Request message. Configurations can include the:
+
+- ability to pass messages from newer versions of [ANSI/SCTE 35] that the splicer revision does not understand;
+- ability to not pass bandwidth reservation messages; this should be the default setting;
+- ability to not pass Splice\_Null messages unless they have descriptors attached;
+- ability to not pass messages that cannot be decrypted.
+
+#### 7.4.1 Cue\_Request message
+
+The data( ) field for this message contains the Cue\_Request\_Data structure outlined below.
+
+**Table 7-5 – Cue\_Request\_Data**
+
+| Syntax                                                       | Bytes | Type |
+|--------------------------------------------------------------|-------|------|
+| Cue_Request_Data {<br>time( )<br>splice_info_section( )<br>} |       |      |
+
+time( ) – This time is derived from the splice\_time( ) in the splice\_info\_section( ) of the ANSI/SCTE 35 cueing message by the splicer. If component splice mode is used in the ANSI/SCTE 35 splice\_info\_section, the time( ) will refer to the default splice time detailed in Section 7.5.2.1 of [ANSI/SCTE 35]. In the case where the splice\_info\_section( ) does not contain a pts\_time( ) that requires translation as in the splice\_schedule( ) command, then the time structure shall be filled with all 1 s to denote no time specified. It is up to the splicer to determine how to map
+
+the PTS time to UTC for communication with the server. This may vary for different splicers in order for them to properly manage their internal buffers. See clause 8.4 for the `time()` structure syntax.
+
+`splice_info_section()` – The details of the structure can be found in [ANSI/SCTE 35].
+
+### 7.5 Splice messages
+
+After initializing and configuring the splicer, the server can issue the **Splice\_Request** message to initiate a session. The two messages that are returned from the **Splice\_Request** message are the **Splice\_Response** message and the **SpliceComplete\_Response** message. The server shall send a **Splice\_Request** message at least 3 seconds prior to the `time()` in the **Splice\_Request** message. This allows the splicer to set up its configuration and prepare for the splice. The insertion channel stream for the session must start between 300 and 600 milliseconds before `time()` as measured at the splicer input. A program clock reference (PCR) must be sent on or before the first video access unit of the insertion channel stream. The video stream of the insertion content shall start with a sequence header and an I-Frame. The splicer shall allow a minimum of 10 queued **Splice\_Request** messages on a given API connection. If the splicer's message queue is full it will respond with the result code 114 (Splice Queue Full).
+
+The details of the physical connection are supplied in the **Init\_Request** message. There are two ways to indicate which channel in the insertion multiplex and which PIDs to use:
+
+- If the **ServiceID** is not 0xFFFF in the **Splice\_Request** message, the **ServiceID** field specifies the program number in the PAT which points to an associated PMT. The PAT and PMT must be stable in the insertion channel at least 200 ms before the **Splice\_Request** message is sent and must remain stable for the duration of the session. These must be legal MPEG tables with revision increments as appropriate.
+- If the **ServiceID** is 0xFFFF, use the `splice_elementary_stream()` structure (PCR, video, audio and data PIDs) in the **Splice\_Request** message.
+
+NOTE – If this method is used then the **ServiceID** shall be set to 0xFFFF. The splicer shall supply an MPEG-2 compliant transport stream to the output multiplex although the insertion multiplex need not include program specific information (PSI).
+
+The order in which splice messages are sent is important. The first message sent for a given sequence of back-to-back insertions shall utilize `time()`, while all of the other **Splice\_Request** messages may utilize **PriorSession**. The **PriorSession** number must reference an existing session that has not yet completed. In all other cases, an error code 123 is returned pointing to the **PriorSession** or `time()` field.
+
+The server chooses the PIDs of the elementary streams within an insertion multiplex. The PIDs may not be common between adjacent sessions from the same server via the same insertion multiplex. This is because the streams of adjacent sessions will occasionally overlap slightly in time, due to requirements in this API.
+
+#### 7.5.1 Splice\_Request message
+
+The `data()` field for this message contains the **Splice\_Request\_Data** structure outlined below.
+
+**Table 7-6 – Splice\_Request\_Data**
+
+| Syntax                      | Bytes | Type   |
+|-----------------------------|-------|--------|
+| Splice_Request_Data {       |       |        |
+| <b>SessionID</b>            | 4     | uimsbf |
+| <b>PriorSession</b>         | 4     | uimsbf |
+| time( )                     |       |        |
+| <b>ServiceID</b>            | 2     | uimsbf |
+| if (ServiceID = 0xFFFF)     |       |        |
+| {                           |       |        |
+| <b>PcrPID</b>               | 2     | uimsbf |
+| <b>PIDCount</b>             | 4     | uimsbf |
+| for (j=0; j<PidCount; j++)  |       |        |
+| splice_elementary_stream( ) |       |        |
+| }                           |       |        |
+| <b>Duration</b>             | 4     | uimsbf |
+| <b>SpliceEventID</b>        | 4     | uimsbf |
+| <b>PostBlack</b>            | 4     | uimsbf |
+| <b>AccessType</b>           | 1     | uimsbf |
+| <b>OverridePlaying</b>      | 1     | uimsbf |
+| <b>ReturnToPriorChannel</b> | 1     | uimsbf |
+| for (i=0; i<N; i++)         |       |        |
+| splice_API_descriptor( )    |       |        |
+| }                           |       |        |
+| }                           |       |        |
+
+**SessionID** – Identifier for the session. Used to distinguish this request from other requests that have been or are going to be issued. Multiple concurrent **Splice\_Request** messages with the same **SessionID** are not permitted. If the **ExtendedData\_Request** is used, an **ExtendedData\_Response** must be received for that **SessionID** before that **SessionID** is reused. This field shall not have the value of 0xFFFFFFFF. Early versions of this standard (with Revision\_Num = 0 or 1) allow the value 0xFFFFFFFF.
+
+**PriorSession** – This field allows a simplified method of performing back-to-back insertions. The value of this field contains the **SessionID** of the session that immediately precedes it. When the value of this field is 0xFFFFFFFF, it indicates that this session uses time( ) to initiate its insertion, rather than the **SessionID** of the preceding session. This field shall have a valid **SessionID** only when the immediately preceding session originated from the same server. The time( ) field- rather than the **PriorSession** field- must be used when creating back-to-back insertions from multiple servers.
+
+time( ) – The splice time for the event. This field will typically be the time( ) field from the **Cue\_Request** message being echoed back to the splicer. If the event was not triggered by a **Cue\_Request**, then this is the time that the server forces a splice event. This field is ignored if the **PriorSession** is not equal to 0xFFFFFFFF. If this value is not related to an ANSI/SCTE 35 cue message, there may be variation between splicers, depending on the buffer and splicing models of each, as to when the actual splice occurs. See clause 8.4 for the time( ) structure syntax.
+
+**ServiceID** – The program number of the channel in the insertion multiplex which will be spliced in place of the primary channel. If this is set to 0xFFFF the splice\_elementary\_stream( ) and **PIDCount** are required.
+
+**PCR** – Indicates the PCR PID.
+
+**PIDCount** – The number of PIDs in the insertion channel (not including the PCR PID).
+
+**Duration** – The number of 90 kHz clock ticks the server is requesting the splicer to insert. This field may override the ANSI/SCTE 35 duration value. This can be set to 0 to indicate that the splicer shall switch to the insertion channel until a new **Splice\_Request** or **Abort\_Request** arrives.
+
+**SpliceEventID** – This is used to relate this insertion event back to the ANSI/SCTE 35 cue message that may have caused this splice to happen. This shall be equivalent to the splice\_event\_id from the splice\_insert command of the associated ANSI/SCTE 35 cue message. This should be the same for all **Splice\_Request** messages pertaining to the same ANSI/SCTE 35 cue message. For an event that was not initiated by an ANSI/SCTE 35 cue message, this field will be set to 0xFFFFFFFF.
+
+**PostBlack** – Number of 90 kHz clock ticks of black video and muted audio to be played at the end of the insertion content playback. The **PostBlack** interval follows and is not included in the length of time specified by the **Duration**. If no **PostBlack** is requested then this field will be set to 0. **PostBlack** shall not be considered part of the currently playing insertion for the purposes of the **OverridePlaying** flag.
+
+**AccessType** – Indicates the type of access this connection has. This is an integer from 0 to 9 with 0 being low priority and 9 being the highest priority.
+
+**OverridePlaying** – When this flag is equal to 0, this **Splice\_Request** cannot override a currently playing insertion. If this flag is set to 1, then this **Splice\_Request** shall override any equal or lower priority currently playing insertion. A currently playing insertion occurs between the splice-in and the splice-out points.
+
+**ReturnToPriorChannel** – When this flag is equal to 0, the splicer shall not return to the primary channel or the overridden insertion channel at the completion of this **Splice\_Request**. It is expected that a new **Splice\_Request** will be issued before this insertion completes. If a new **Splice\_Request** is not received, then the splicer shall stop transmitting on this output channel. When this flag is equal to 1, it shall return to the prior channel unless a subsequent **Splice\_Request** is received to indicate otherwise.
+
+splice\_API\_descriptor( ) – A descriptor that must follow the syntax defined in clause 8.5. The playback\_descriptor( ) and muxpriority\_descriptor( ) are appropriate descriptors for this clause.
+
+#### 7.5.2 Splice\_Response message
+
+The data() field for the Splice\_Response message contains the **Splice\_Response\_Data** structure outlined below. The **Splice\_Response\_Message** may contain an error code if appropriate. The **Splice\_Offset** is used by the splicer to inform the server of a time offset for the delivery of the content for this message. This does not affect the point in the primary channel where the splice will occur.
+
+**Table 7-7 – Splice\_Response\_Data**
+
+| Syntax                                              | Bytes | Type    |
+|-----------------------------------------------------|-------|---------|
+| Splice_Response_Data {<br><b>Splice_Offset</b><br>} | 2     | tcimsbf |
+
+**Splice\_Offset** – This shall be set to zero unless used to send delay information. The offset information is in milliseconds. A negative value is a request for the insertion channel content to be delivered earlier; a positive value is a request for the insertion channel content to be delivered later.
+
+The **Splice\_Offset** field is expected to be used by splicing devices which achieve seamless operation by altering the primary channel propagation delay through the splicer. When such a device is commanded to splice in the absence of ANSI/SCTE 35 cue messages, the splicer does not have the opportunity to advance or retard the ad server's ad timing via alteration of the equation in converting pts\_time to UTC time (because there are no ANSI/SCTE 35 cue messages and hence no conversion and no cue request messages). In such a case, a splicer may utilize the new **Splice\_Offset** field to advance or retard the ad server to match the splicer's output service timing following each **Splice\_Request** message.
+
+#### 7.5.3 SpliceComplete\_Response message
+
+The **SpliceComplete\_Response** message is sent when the insertion starts and finishes. This is true for back-to-back insertions as well. For example, if two pieces of content play, four **SpliceComplete\_Response** messages are returned, one at the start of the first piece of content, one upon completion of the first piece of content, one upon the start of the second piece of content and one upon completion of the second piece of content. The result code in the header shall properly indicate the failure reason if the splice failed so that the server can take appropriate action. The splice-in and splice-out are separate events and shall be treated as such. If a splice between two pieces of content fails, the splice-out should indicate good status if the current piece of content is played in its entirety. The **SpliceComplete\_Response** message shall be sent immediately upon failure of any splice event and shall not wait until the expected duration of the inserted content.
+
+The data( ) field for this message contains the **SpliceComplete\_Response\_Data** structure outlined below.
+
+**Table 7-8 – SpliceComplete\_Response\_Data**
+
+| Syntax                          | Bytes | Type   |
+|---------------------------------|-------|--------|
+| SpliceComplete_Response_Data {  |       |        |
+| <b>SessionID</b>                | 4     | uimsbf |
+| <b>SpliceTypeFlag</b>           | 1     | uimsbf |
+| if ( <b>SpliceTypeFlag</b> = 0) |       |        |
+| {                               |       |        |
+| time( )                         |       |        |
+| } else                          |       |        |
+| {                               |       |        |
+| <b>Bitrate</b>                  | 4     | uimsbf |
+| <b>PlayedDuration</b>           | 4     | uimsbf |
+| }                               |       |        |
+| }                               |       |        |
+
+**SessionID** – The session ID that the **Splice\_Request** message used.
+
+**SpliceTypeFlag** – This field shall be a 0 to indicate a splice-in (start) and a 1 to indicate a splice-out (end).
+
+time( ) – The time that the splicer detected the first byte of the insertion stream from the server. The server may utilize this time( ) to adjust the arrival time at the splicer, of subsequent insertion channel content when the delivery mechanism is known to have a time varying latency.
+
+**Bitrate** – This is the average bit rate for the session. This field is in bits-per-second (bps) including transport packet overhead for this channel.
+
+**PlayedDuration** – This is the number of 90 kHz clock ticks actually played. This is exclusive of any post-black or transition frames.
+
+### 7.6 Alive messages
+
+Once the initialization is complete, the server can send **Alive\_Request** messages to ensure that the splicer is still up and running. Each **Alive\_Response** message contains a status from the splicer to the server. This status indicates the state of the device. If there has been no activity on the TCP/IP connection in the preceding 60 seconds, then an **Alive\_Request** message shall be sent.
+
+#### 7.6.1 Alive\_Request message
+
+The data( ) field for the **Alive\_Request** message contains the **Alive\_Request\_Data** structure outlined below.
+
+**Table 7-9 – Alive\_Request\_Data**
+
+| Syntax                             | Bytes | Type |
+|------------------------------------|-------|------|
+| Alive_Request_Data{<br>time()<br>} |       |      |
+
+time( ) – The current UTC time clock of the sending device checked as close as possible to the sending of the message. This is designed to be used by the splicer and the server to check on how well the two systems are time synchronized. It is not expected that this will allow the systems to synchronize well enough to allow reliable splicing to occur, but the implementers may use this as they wish. See clause 8.4 for the time( ) structure syntax.
+
+#### 7.6.2 Alive\_Response message
+
+The data( ) field for the **Alive\_Response** message contains the **Alive\_Response\_Data** structure outlined below.
+
+**Table 7-10 – Alive\_Response\_Data**
+
+| Syntax               | Bytes | Type   |
+|----------------------|-------|--------|
+| Alive_Response_Data{ |       |        |
+| <b>State</b>         | 4     | uimsbf |
+| <b>SessionID</b>     | 4     | uimsbf |
+| time( )              |       |        |
+| }                    |       |        |
+
+**State** – This describes the state of the output channel.
+
+**Table 7-11 – Alive\_Response message states**
+
+| State | Description          |
+|-------|----------------------|
+| 0x00  | No output            |
+| 0x01  | On primary channel   |
+| 0x02  | On insertion channel |
+
+**SessionID** – The **SessionID** of the currently playing insertion. Valid only for **State** = 0x02.
+
+**time()** – The current UTC time clock of the sending device checked as close as possible to the sending of the message. This is designed to be used by the splicer and the server to check on how well the two systems are time synchronized. It is not expected that this will allow the systems to synchronize well enough to allow reliable splicing to occur, but the implementers may use this as they wish. See clause 8.4 for the **time()** structure syntax.
+
+### 7.7 Extended data messages
+
+This is a splicer defined structure to send detailed data about the playback to the server. After the **SpliceComplete\_Response** has been received, then the extended data can be retrieved using the **ExtendedData\_Request**. The **SessionID** used in this message is the same as the **SessionID** used in setting up this session and in the **SpliceComplete\_Response**.
+
+#### 7.7.1 ExtendedData\_Request message
+
+The **data()** field for this message contains the **ExtendedData\_Request\_Data** structure outlined below.
+
+**Table 7-12 – ExtendedData\_Request\_Data**
+
+| Syntax                      | Bytes | Type   |
+|-----------------------------|-------|--------|
+| ExtendedData_Request_Data { |       |        |
+| <b>SessionID</b>            | 4     | uimsbf |
+| <b>ExtendedDataType</b>     | 4     | uimsbf |
+| }                           |       |        |
+
+**SessionID** – The **SessionID** of the completed session.
+
+**ExtendedDataType** – The requested response data type from the splicer to the **ExtendedData\_Response** message. This value may be set to 0xFFFFFFFF to indicate that the default data type is to be returned. This standard reserves 0x00000000 to 0x7FFFFFFF for future standardization. The range 0x80000000 to 0xFFFFFE is for vendor unique usage.
+
+#### 7.7.2 ExtendedData\_Response message
+
+The server shall use the **MessageSize** field to determine the amount of data it is required to read via the **ExtendedData\_Response** message.
+
+The **data()** field for this message contains the **ExtendedData\_Response\_Data** structure outlined below.
+
+**Table 7-13 – ExtendedData\_Response\_Data**
+
+| Syntax                         | Bytes | Type   |
+|--------------------------------|-------|--------|
+| ExtendedData_Response_Data {   |       |        |
+| <b>SessionID</b>               | 4     | uimsbf |
+| for(i=0;i<n;i++)               |       |        |
+| <b>splice_API_descriptor()</b> |       |        |
+| }                              |       |        |
+
+**SessionID** – The **SessionID** that these data are valid for.
+
+**splice\_API\_descriptor()** – A descriptor of the format defined in clause 8.5 that is splicer defined.
+
+### 7.8 Abort messages
+
+The server can send an **Abort\_Request** at any time which will cause the splicer to immediately revert to the overridden insertion channel or primary channel. The splicer shall send an **Abort\_Response** message to acknowledge the receipt of the **Abort\_Request**. A **SpliceComplete\_Response** with a result code 116 (Insertion Aborted) is sent if the **Abort\_Request** caused a splice-out of the insertion. If no splice-out was needed then no **SpliceComplete\_Response** message shall be reported.
+
+All pending back-to-back insertions linked via the **PriorSession** field of the **Splice\_Request** message to the **SessionID** of an **Abort\_Request** message shall also be aborted. An error message shall be returned for each aborted **SessionID**. Consider the following example: three insertions are cued to run sequentially within a block of time – the first event is time-based; the second event is linked to the first **SessionID** using the **PriorSession**; the third event is linked to the second **SessionID** using that **PriorSession**. In this example, if the first insertion event is aborted, the two subsequently cued insertion events will also be aborted. The abort message does not abort any insertions that use a different API connection from a server to a splicer. The next splice that occurs for the primary channel requires the **PriorSession** in the splice message to be 0xFFFFFFFF.
+
+### 7.9 Abort\_Request message
+
+The data( ) field for this message contains the **Abort\_Request\_Data** structure outlined below.
+
+**Table 7-14 – Abort\_Request\_Data**
+
+| Syntax                                        | Bytes | Type   |
+|-----------------------------------------------|-------|--------|
+| Abort_Request_Data {<br><b>SessionID</b><br>} | 4     | uimsbf |
+
+**SessionID** – The **SessionID** and all subsequent sessions linked through the **PriorSession** field that are to be aborted.
+
+### 7.10 Abort\_Response message
+
+The **Abort\_Response** indicates that the **Abort\_Request** message was received. This message may contain a result code if appropriate.
+
+The data( ) field for this message contains the **Abort\_Response\_Data** structure outlined below.
+
+**Table 7-15 – Abort\_Response\_Data**
+
+| Syntax                                         | Bytes | Type   |
+|------------------------------------------------|-------|--------|
+| Abort_Response_Data {<br><b>SessionID</b><br>} | 4     | uimsbf |
+
+**SessionID** – The **SessionID** and all subsequent sessions linked through the **PriorSession** field that were aborted.
+
+### 7.11 TearDownFeed\_Request message
+
+The **TearDownFeed\_Request** message contains no data and is only valid for the connection this message is sent over. This message is used to tear down feeds created by the **Init\_Request** message with the **create\_feed\_descriptor()**. This message is used to tear down only those feeds.
+
+### 7.12 TearDownFeed\_Response message
+
+The **TearDownFeed\_Response** message contains no data and indicates that the **TearDownFeed\_Request** message was received and the action occurred. This message may contain a result code if appropriate.
+
+### 7.13 Requesting configuration settings
+
+The current configuration settings for the API connection can be returned. This includes some of the information in the **Init\_Request**. The **GetConfig\_Request** contains no additional data.
+
+#### 7.13.1 GetConfig\_Request message
+
+The **GetConfig\_Request** message contains no data.
+
+#### 7.13.2 GetConfig\_Response message
+
+The **data()** field for this message contains the **GetConfig\_Response\_Data** structure outlined below.
+
+**Table 7-16 – GetConfig\_Response\_Data**
+
+| Syntax                                                                                                | Bytes | Type   |
+|-------------------------------------------------------------------------------------------------------|-------|--------|
+| GetConfig_Response_Data {<br><b>ChannelName</b><br>Hardware_Config()<br>TS_program_map_section()<br>} | 32    | String |
+
+**ChannelName** – Logical name given to the output channel of this connection.
+
+**Hardware\_Config()** – See clause 8.2 for the syntax of the **Hardware\_Config()** structure.
+
+**TS\_program\_map\_section()** – This is the entire PMT section for the output channel as defined in [ITU-T H.222.0]. If the splicer changes the PMT, it should signal this change to the server with a result code 128 in the **General\_Response** message.
+
+### 7.14 General\_Response message
+
+The **General\_Response** message is used to convey asynchronous information between the server and the splicer. There is no **data()** associated with this message. Any result code may be sent in this message. This message will typically be used to indicate output channel PMT changes or invalid request messages.
+
+# 8 Additional structures
+
+### 8.1 Version
+
+The "Version" structure is used to maintain the proper versioning within the API. It is expected that this API will evolve over time and to allow for this expansion, the version is specified in the **Init\_Request** and **Init\_Response** messages to ensure that the splicer supports the same version as the server.
+
+**Table 8-1 – Version( )**
+
+| Syntax                                | Bytes | Type   |
+|---------------------------------------|-------|--------|
+| Version {<br><b>Revision_Num</b><br>} | 2     | uimsbf |
+
+**Revision\_Num** – This field is two (2) in this version.
+
+The server and splicer should set and check this field to ensure that both components are capable of operating at the appropriate revision.
+
+### 8.2 Hardware\_Config
+
+This structure describes the hardware interface between the server and the splicer. It is important for the splicer to know exactly where the server is connected so that the splicer knows what multiplex is being referenced. An example of this link would be a DVB-ASI connection from the server to the splicer.
+
+**Table 8-2 – Hardware\_Config( )**
+
+| Syntax                        | Bytes | Type   |
+|-------------------------------|-------|--------|
+| Hardware_Config{              |       |        |
+| <b>Length</b>                 | 2     | uimsbf |
+| <b>Chassis</b>                | 2     | uimsbf |
+| <b>Card</b>                   | 2     | uimsbf |
+| <b>Port</b>                   | 2     | uimsbf |
+| <b>Logical_Multiplex_Type</b> | 2     | uimsbf |
+| <b>Logical_Multiplex( )</b>   |       | uimsbf |
+| }                             |       |        |
+
+**Length** – This gives the length in bytes of this structure following this field.
+
+**Chassis** – An integer indicating to which splicer chassis the server's insertion multiplex is connected. In cases where the card is labelled alphabetically the translation is made to an integer value (i.e., A – 1; B – 2, etc.).
+
+**Card** – An integer indicating the splicer card to which the server's insertion multiplex is connected. In cases where the card is labelled alphabetically the translation is made to an integer value (i.e., A – 1; B – 2, etc.).
+
+**Port** – The hardware port number where the server's insertion multiplex is connected.
+
+**Logical\_Multiplex\_Type** – A value from the following table:
+
+**Table 8-3 – Logical multiplex type**
+
+| Type   | Bytes    | Name         | Description                                                                                                                                      |
+|--------|----------|--------------|--------------------------------------------------------------------------------------------------------------------------------------------------|
+| 0x0000 | 0        | Not used     | The <b>Logical_Multiplex</b> field is not needed to identify the multiplex.                                                                      |
+| 0x0001 | Variable | User defined | The usage of the <b>Logical_Multiplex</b> field is not defined by this specification and must be agreed upon between the splicer and the server. |
+
+**Table 8-3 – Logical multiplex type**
+
+| Type          | Bytes    | Name                           | Description                                                                                                                                                                                                                                                                                                                                                                                                             |
+|---------------|----------|--------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 0x0002        | 6        | MAC address                    | The <b>Logical_Multiplex</b> field contains the IEEE Media Access Control address of the multiplex as a 6-byte address.                                                                                                                                                                                                                                                                                                 |
+| 0x0003        | 6        | IPv4 address                   | The most significant 4 bytes of the <b>Logical_Multiplex</b> field contain the Internet Protocol (IP) address of the multiplex, and the remaining 2 bytes contain the IP port number where the multiplex can be found.                                                                                                                                                                                                  |
+| 0x0004        | 18       | IPv6 address                   | The most significant 16 bytes of the <b>Logical_Multiplex</b> field contain the Internet Protocol (IPv6) address of the multiplex, and the remaining 2 bytes contain the IP port number where the multiplex can be found.                                                                                                                                                                                               |
+| 0x0005        | 5        | ATM address                    | The <b>Logical_Multiplex</b> field contains the coordinates of the asynchronous transfer mode (ATM) circuit over which the multiplex is carried. The most significant two bytes of the logical multiplex field contain the virtual path identifier (VPI) and the next two bytes contain the virtual channel identifier (VCI) of the circuit. The least significant byte contains the ATM adaptation layer (AAL) number. |
+| 0x0006        | Variable | IPv4 address with SPTS support | See description following this table.                                                                                                                                                                                                                                                                                                                                                                                   |
+| 0x0007        | Variable | IPv6 address with SPTS support | See description following this table.                                                                                                                                                                                                                                                                                                                                                                                   |
+| 0x0008-0xFFFF | Variable | Reserved                       | Reserved for future standardization.                                                                                                                                                                                                                                                                                                                                                                                    |
+
+#### **Type 0x0006 – IPv4 address with single program transport stream (SPTS) support**
+
+Type 0x0006 is utilized by VOD and ad servers where remapping of PIDs is impractical or undesirable. In these cases it is desirable to use an SPTS per UDP port.
+
+**Table 8-4 – Type 0x0006 structure**
+
+| Syntax                                                 | Bytes | Type   |
+|--------------------------------------------------------|-------|--------|
+| Type 0x0006 structure {                                |       |        |
+| <b>number_of_destination_ips</b>                       | 1     | uimsbf |
+| for (j=0; j< <b>number_of_destination_ips</b> ; j++) { |       |        |
+| <b>dest_ip_address</b>                                 | 4     | uimsbf |
+| }                                                      |       |        |
+| <b>number_of_source_ips</b>                            | 1     | uimsbf |
+| for (j=0; j< <b>number_of_source_ips</b> ; j++) {      |       |        |
+| <b>source_ip_address</b>                               | 4     | uimsbf |
+| }                                                      |       |        |
+| <b>base_port</b>                                       | 2     | uimsbf |
+| <b>number_of_ports</b>                                 | 1     | uimsbf |
+| }                                                      |       |        |
+
+**number\_of\_destination\_ips** – Specifies how many **dest\_ip\_address(es)** follow. The valid range is 1 to 32.
+
+**dest\_ip\_address** – The IPv4 address that the splicer shall use for the content associated with the splice.
+
+**number\_of\_source\_ips** – Specifies how many **source\_ip\_address(es)** follow. The valid range is 0-32.
+
+**source\_ip\_address** – The source IPv4 address(es) that the splicer may use in an IGMP V3 join for the associated multicast **dest\_ip\_address(es)**.
+
+**base\_port** – The initial UDP port that the splicer shall use for the content associated with a Splice\_Request with time( ) specified. The base UDP port range shall be assigned by IANA.
+
+**number\_of\_ports** – This byte contains the number of contiguous ports to reserve. The **number\_of\_ports** value may range from 1 to 4 and includes the base port. Allowed port numbers are determined, in order, by the base port, followed by base Port +1, followed by base Port +2, followed by base Port +3.
+
+All Splice\_Requests that use time( ) shall use the base IPv4 address:port unless the port\_selection\_descriptor( ) is used. The first Splice\_Request of an avail shall use time( ). Subsequent sessions of the same avail that also use time( ) shall also use the base IPv4 address:port unless the port\_selection\_descriptor( ) is used. The next and subsequent splice\_requests using PriorSession instead of time( ), shall use the base IP and port+1, then port+2 and so on until the requested number of ports is used and it shall then revert to the base port for the next splice\_request.
+
+The port\_selection\_descriptor( ) may be utilized in any Splice\_Request command that has a hardware config with Logical\_Multiplex type 0x0006 to alter the default operation of the ports.
+
+The port may be any valid unicast or multicast IPv4 address:port combination. The splicer shall perform an IGMP join on a multicast IP.
+
+**Logical\_Multiplex** – If the **Port** carries multiple insertion multiplexes on a single input, then this field allows the splicer to determine which to use when splicing from this server. The meaning and format of this field is defined by the **Logical\_Multiplex\_Type** field. In the event that a non-standard definition for the **Logical\_Multiplex** is required, the **Logical\_Multiplex\_Type** shall be set to 1 for user defined.
+
+#### **Type 0x0007 – IPv6 address with single program transport stream (SPTS) support**
+
+Type 0x0007 is utilized by VOD and ad servers where remapping of PIDs is impractical or undesirable. In these cases it is desirable to use an SPTS per UDP port.
+
+**Table 8-5 – Type 0x0007 structure**
+
+| Syntax                                               | Bytes | Type   |
+|------------------------------------------------------|-------|--------|
+| Type 0x0007 structure {                              |       |        |
+| <b>number_of_destination_ips</b>                     | 1     | uimsbf |
+| for (j=0; j< <b>number_of_destination_ips</b> ; j++) |       |        |
+| {                                                    |       |        |
+| <b>dest_ip_address</b>                               | 16    | uimsbf |
+| }                                                    |       |        |
+| <b>number_of_source_ips</b>                          | 1     | uimsbf |
+| for (j=0; j< <b>number_of_source_ips</b> ; j++) {    |       |        |
+
+**Table 8-5 – Type 0x0007 structure**
+
+| Syntax                   | Bytes | Type   |
+|--------------------------|-------|--------|
+| <b>source_ip_address</b> | 16    | uimsbf |
+| }                        |       |        |
+| <b>base_port</b>         | 2     | uimsbf |
+| <b>number_of_ports</b>   | 1     | uimsbf |
+| }                        |       |        |
+
+**number\_of\_destination\_ips** – Specifies how many **dest\_ip\_address(es)** follow. The valid range is 1 to 32.
+
+**dest\_ip\_address** – The IPv6 address that the splicer shall use for the content associated with the splice.
+
+**number\_of\_source\_ips** – Specifies how many **source\_ip\_address(es)** follow. The valid range is 0-32.
+
+**source\_ip\_address** – The source IPv6 address(es) that the splicer may use in an MLD V2 join for the associated multicast **dest\_ip\_address(es)**.
+
+**base\_port** – The initial UDP port that the splicer shall use for the content associated with a Splice\_Request with time( ) specified. The base UDP port range shall be assigned by IANA.
+
+**number\_of\_ports** – This byte contains the number of contiguous ports to reserve. The number\_of\_ports value may range from 1 to 4 and includes the base port. Allowed port numbers are determined, in order, by the base port, followed by base Port +1, followed by base Port +2, followed by base Port +3.
+
+All Splice\_Requests that use time( ) shall use the base IPv6 address:port unless the port\_selection\_descriptor( ) is used. The first Splice\_Request of an avail shall use time( ). Subsequent sessions of the same avail that also use time( ) shall also use the base IPv6 address:port unless the port\_selection\_descriptor( ) is used. The next and subsequent splice\_requests using PriorSession instead of time( ), shall use the base IP and port+1, then port+2 and so on until the requested number of ports is used and it shall then revert to the base port for the next splice\_request.
+
+The port\_selection\_descriptor( ) may be utilized in any Splice\_Request command that has a hardware config with Logical\_Multiplex type 0x0007 to alter the default operation of the ports.
+
+The port may be any valid unicast or multicast IPv6 address:port combination. The splicer shall perform an MLD join on a multicast IP.
+
+### **8.3 splice\_elementary\_stream( )**
+
+Packet identifiers (PIDs) are identifiers for parts of the transport stream, video, audio, data, etc. This structure is used to describe one of the elements in the program in the MPTS. The **Splice\_Request** message may contain a splice\_elementary\_stream( ) structure for each of the transport stream components (except for the PCR PID). The **StreamTypes** are based on the MPEG PMT table definitions.
+
+This specification has not defined how to map multiple audio/video/data PIDs to output PIDs. It has also not defined splicer behaviour when multiple audio tracks may be either present or missing in the insertion channel compared with the primary channel.
+
+**Table 8-6 – splice\_elementary\_stream( )**
+
+| Syntax                     | Bytes | Type   |
+|----------------------------|-------|--------|
+| splice_elementary_stream { |       |        |
+| <b>Length</b>              | 1     | uimsbf |
+| <b>PID</b>                 | 2     | uimsbf |
+| <b>StreamType</b>          | 2     | uimsbf |
+| <b>AvgBitrate</b>          | 4     | uimsbf |
+| <b>MaxBitrate</b>          | 4     | uimsbf |
+| <b>MinBitrate</b>          | 4     | uimsbf |
+| <b>HResolution</b>         | 2     | uimsbf |
+| <b>VResolution</b>         | 2     | uimsbf |
+| for(i=0;I<N;I++)           |       |        |
+| descriptor( )              |       |        |
+| }                          |       |        |
+
+The PCR PID is required.
+
+**Length** – Total length in bytes of the splice\_elementary\_stream( ) structure including this field.
+
+**PID** – The PID number that is being used. This is a 2-byte field (16 bits) and shall contain the 13-bit PID right aligned as a 16-bit integer. (0x0000 to 0x1FFF)
+
+**StreamType** – The type of PID (audio, video, etc.). This number corresponds with the PMT specification found in [ITU-T H.222.0].
+
+**AvgBitrate** – The bit rate for this PID averaged over the entire piece of content in bits-per-second (bps). This is set to 0xFFFFFFFF if the bit rate is not known.
+
+**MaxBitrate** – The maximum bit rate for this PID. This is set to 0xFFFFFFFF if the bit rate is not known.
+
+**MinBitrate** – The minimum bit rate for this PID. This is set to 0xFFFFFFFF if the bit rate is not known.
+
+**HResolution** – The width in number of pixels of the video pictures using this PID. If the PID does not contain video pictures or if the server cannot supply this value, it shall be set to 0xFFFF.
+
+**VResolution** – The height in number of pixels of the video pictures using this PID. If the PID does not contain video pictures or if the server cannot supply this value, it shall be set to 0xFFFF.
+
+descriptor( ) – Any valid descriptor used in a PMT. For multiple audio PIDs the language descriptors as defined in [ITU-T H.222.0] are required.
+
+### 8.4 time( ) field definition
+
+The time structure is used to define various times in this specification.
+
+**Table 8-7 – time( )**
+
+| Syntax              | Bytes | Type   |
+|---------------------|-------|--------|
+| time {              |       |        |
+| <b>Seconds</b>      | 4     | uimsbf |
+| <b>MicroSeconds</b> | 4     | uimsbf |
+| }                   |       |        |
+
+**Seconds** – Elapsed seconds since 12:00 AM January 1, 1970 UTC.
+
+**MicroSeconds** – Offset in microseconds of the **Seconds** field.
+
+### 8.5 splice\_API\_descriptor( ) field definition
+
+This is a template for adding descriptors in any message defined within this Recommendation. The **Splice\_Request**, **ExtendedData\_Response** and **Init\_Request** messages may use descriptors. The use of descriptors in messages defined by this standard is optional. The following table is the general format for descriptors used in this standard.
+
+**Table 8-8 – splice\_api\_descriptor( )**
+
+| Syntax                       | Bytes | Type   |
+|------------------------------|-------|--------|
+| splice_API_descriptor {      |       |        |
+| <b>Splice_Descriptor_Tag</b> | 1     | uimsbf |
+| <b>Descriptor_Length</b>     | 1     | uimsbf |
+| <b>Splice_API_Identifier</b> | 4     | uimsbf |
+| for (i=0;i<n;i++)            |       |        |
+| <b>Private Byte</b>          | 1     | uimsbf |
+| }                            |       |        |
+
+**Splice\_Descriptor\_Tag** – A value from 0x00 to 0xFF to denote the specific descriptor being used. Tag values 0x00 to 0xFF are reserved for use by this standard. The vendor may use a vendor unique **Splice\_API\_Identifier** to allow for a larger tag range and a more robust method of adding vendor unique descriptors.
+
+**Descriptor\_Length** – This gives the length in bytes of the descriptor following this field. Descriptors are limited to 256 bytes, so this value is limited to 254.
+
+**Splice\_API\_Identifier** – An identifier of the organization that has defined this descriptor. For all descriptors within this Recommendation, the identifier is 0x53415049 (ASCII "SAPT"). This has been chosen to not conflict with descriptors of any other known identifier.
+
+**Private Byte** – The remainder of the descriptor is dedicated to data fields as required by the descriptor being defined.
+
+#### 8.5.1 playback\_descriptor( ) field definitions
+
+The **playback\_descriptor( )** is an implementation of the **splice\_API\_descriptor( )** which is intended for use in the **Splice\_Request** message.
+
+The abort criteria examine the playback rate, defined as the output channel's bit rate averaged over a one second period. The sliding displacement of the averaging window is recommended to be one second or less.
+
+**Table 8-9 – playback\_descriptor( )**
+
+| Syntax                       | Bytes | Type   |
+|------------------------------|-------|--------|
+| playback_descriptor {        |       |        |
+| <b>Splice_Descriptor_Tag</b> | 1     | uimsbf |
+| <b>Descriptor_Length</b>     | 1     | uimsbf |
+| <b>Splice_API_Identifier</b> | 4     | uimsbf |
+| <b>BitrateRule</b>           | 1     | uimsbf |
+| <b>MinPlaybackRate</b>       | 4     | uimsbf |
+| }                            |       |        |
+
+**Splice\_Descriptor\_Tag** – 0x01.
+
+**Descriptor\_Length** – 0x09.
+
+**Splice\_API\_Identifier** – 0x53415049, ASCII "SAPI".
+
+**BitrateRule** – Flag used to indicate the rules for **MinPlaybackRate**.
+
+**Table 8-10 – BitrateRule values**
+
+| BitrateRule | Description                                                                                                                                                                                                                    |
+|-------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 0x00        | Ignore <b>MinPlaybackRate</b> .                                                                                                                                                                                                |
+| 0x01        | Return a result code 127 immediately using the <b>General_Response</b> message if the playback rate falls below the <b>MinPlaybackRate</b> but do not abort.                                                                   |
+| 0x02        | Abort if the playback rate falls below the <b>MinPlaybackRate</b> .                                                                                                                                                            |
+| 0x03        | Cancel the session prior to the splice-in if the splicer determines that the <b>MinPlaybackRate</b> will not be met. The splicer will send a <b>SpliceComplete_Response</b> or <b>General_Response</b> with a result code 127. |
+
+**MinPlaybackRate** – The minimum aggregate bit rate of the output channel averaged over one second for the duration of the splice that it can play at before the **BitrateRule** is triggered. Setting this value to 0 indicates there is no minimum rate.
+
+#### 8.5.2 muxpriority\_descriptor( ) field definitions
+
+The muxpriority\_descriptor( ) is an implementation of the splice\_API\_descriptor( ) which is intended for use in the **Splice\_Request** message.
+
+**Table 8-11 – muxpriority\_descriptor( )**
+
+| Syntax                       | Bytes | Type   |
+|------------------------------|-------|--------|
+| muxpriority_descriptor {     |       |        |
+| <b>Splice_Descriptor_Tag</b> | 1     | uimsbf |
+| <b>Descriptor_Length</b>     | 1     | uimsbf |
+| <b>Splice_API_Identifier</b> | 4     | uimsbf |
+| <b>MuxPriorityValue</b>      | 1     | uimsbf |
+| }                            |       |        |
+
+**Splice\_Descriptor\_Tag** – 0x02
+
+**Descriptor\_Length** – 0x05
+
+**Splice\_API\_Identifier** – 0x53415049, ASCII "SAPI".
+
+**MuxPriorityValue** – This number ranges from 1 to 10 (1 being the lowest, 5 is the average and 10 being the highest). This number modifies the stored **MuxPriorityValue** of the primary channel in the splicer. A **MuxPriorityValue** of 5 will not modify the output channel's priority. A **MuxPriorityValue** of less than 5 will subtract from the output channel's priority level and a **MuxPriorityValue** greater than 5 will add to the output channel's priority.
+
+Using the **MuxPriorityValue** will not ensure that the content is played with any specific level of quality. The actual effect of the **MuxPriorityValue** depends on the overall spliced multiplex configuration and how much the splicer needs to lower the total multiplex bit rate at any given time. This will also be dependent on how the splicer operates and as such will be a very splicer vendor dependent field.
+
+#### 8.5.3 missing\_Primary\_Channel\_action\_descriptor( ) field definitions
+
+The missing\_Primary\_Channel\_action\_descriptor( ) is an implementation of the splice\_API\_descriptor( ) which is intended for use in the **Init\_Request** message.
+
+If the primary channel has terminated for any reason during an insertion, the result at the decoder may be to display a freeze-frame of the last inserted frame at the conclusion of the insertion. This descriptor allows the splicer to be directed to insert black video and silent audio in order to clear the decoder's buffer, if the primary channel is no longer present when it would normally become the output audio/video source.
+
+**Table 8-12 – missing\_Primary\_Channel\_action\_descriptor ( )**
+
+| Syntax                                      | Bytes | Type   |
+|---------------------------------------------|-------|--------|
+| missing_Primary_Channel_action_descriptor { |       |        |
+| <b>Splice_Descriptor_Tag</b>                | 1     | uimsbf |
+| <b>Descriptor_Length</b>                    | 1     | uimsbf |
+| <b>Splice_Api_Identifier</b>                | 4     | uimsbf |
+| <b>MissingPrimaryChannelAction</b>          | 1     | uimsbf |
+| }                                           |       |        |
+
+**Splice\_Descriptor\_Tag** – 0x03
+
+**Descriptor\_Length** – 0x05
+
+**Splice\_API\_Identifier** – 0x53415049, ASCII "SAPI".
+
+**MissingPrimaryChannelAction** – This parameter has three possible values, 0, 1 and 2. A value of 0 means do nothing. A value of 1 means insert one black I frame and one frame of audio silence. A value of 2 means continue to transmit black and silence until the primary signal returns.
+
+#### 8.5.4 port\_selection\_descriptor( ) field definitions
+
+The port\_selection\_descriptor( ) is an implementation of the splice\_API\_descriptor( ) which shall only be used in the **Splice\_Request** message when the logical multiplex type 0x0006 or 0x0007 is used in the hardware configuration. If during a sequence of insertions the server sends a port\_selection\_descriptor( ), the server shall continue to send the port\_selection\_descriptor( ) until the next Splice\_Request based on time occurs.
+
+The port\_selection\_descriptor( ) may be utilized to alter the default operation of the ports or select a new dynamically set up IPv4 or IPv6 Address:Port combination.
+
+The splicer shall dynamically set up a destination port if the **ps\_ip\_address** was not defined in the hardware config. If the **ps\_ip\_address** is multicast, the splicer shall issue an IGMP join or an MLD join request within 400 milliseconds after the arrival of the Splice\_Request message. Latency for setting up a multicast group shall be less than 2 seconds, which is derived as follows:
+
+The 3 second arrival of the Splice\_Request message (clause 7.5).
+
+Less the 600 milliseconds stream start time (clause 7.5).
+
+Less the 400 milliseconds for the splicer to issue the IGMP join or the MLD join request.
+
+**Table 8-13 – IPv4 port\_selection\_descriptor ( )**
+
+| Syntax                                       | Bytes | Type   |
+|----------------------------------------------|-------|--------|
+| port_selection_descriptor {                  |       |        |
+| <b>Splice_Descriptor_Tag</b>                 | 1     | uimsbf |
+| <b>Descriptor_Length</b>                     | 1     | uimsbf |
+| <b>Splice_API_Identifier</b>                 | 4     | uimsbf |
+| <b>ps_ip_address</b>                         | 4     | uimsbf |
+| <b>ps_port</b>                               | 2     | uimsbf |
+| <b>ps_number_of_source_ip</b>                | 1     | uimsbf |
+| for (j=0; j< <b>ps_number_of_source_ip</b> ; |       |        |
+| j++) {                                       |       |        |
+| <b>ps_source_ip_address</b>                  | 4     | uimsbf |
+| }                                            |       |        |
+| }                                            |       |        |
+
+**Splice\_Descriptor\_Tag** – 0x04
+
+**Descriptor\_Length** – Variable. The length in bytes of the descriptor following this field.
+
+**Splice\_API\_Identifier** – 0x53415049, ASCII "SAPI".
+
+**ps\_ip\_address** – The IPv4 Internet protocol address that the splicer shall use for the content associated with the splice. If this address:port combination is different from the address in the Logical\_Mux\_Type 0x0006 table, it shall be considered a dynamic port set-up request.
+
+**ps\_port** – The UDP port that the splicer shall use for the content associated with the splice. This port number shall override the automatic port selection method of the Logical\_Multiplex\_Type 0x0006.
+
+**ps\_number\_of\_source\_ip** – Specifies how many **ps\_source\_ip\_address(es)** follow. The valid range is 0-32.
+
+**ps\_source\_ip\_address** – The source IPv4 address(es) that the splicer shall use in an IGMP V3 join for the associated multicast **ps\_ip\_address**.
+
+**Table 8-14 – IPv6 port\_selection\_descriptor ( )**
+
+| Syntax                                         | Bytes | Type   |
+|------------------------------------------------|-------|--------|
+| port_selection_descriptor {                    |       |        |
+| <b>Splice_Descriptor_Tag</b>                   | 1     | uimsbf |
+| <b>Descriptor_Length</b>                       | 1     | uimsbf |
+| <b>Splice_API_Identifier</b>                   | 4     | uimsbf |
+| <b>ps_ip_address</b>                           | 16    | uimsbf |
+| <b>ps_port</b>                                 | 2     | uimsbf |
+| <b>ps_number_of_source_ip</b>                  | 1     | uimsbf |
+| for (j=0; j< ps_number_of_source_ip;<br>j++) { |       |        |
+| <b>ps_source_ip_address</b>                    | 16    | uimsbf |
+| }                                              |       |        |
+| }                                              |       |        |
+
+**Splice\_Descriptor\_Tag** – 0x05
+
+**Descriptor\_Length** – Variable. The length in bytes of the descriptor following this field.
+
+**Splice\_API\_Identifier** – 0x53415049, ASCII "SAPI".
+
+**ps\_ip\_address** – The IPv6 Internet protocol address that the splicer shall use for the content associated with the splice. If this address:port combination is different from the address in the Logical\_Mux\_Type 0x0007 table, it shall be considered a dynamic port set-up request.
+
+**ps\_port** – The UDP port that the splicer shall use for the content associated with the splice. This port number shall override the automatic port selection method of the Logical\_Multiplex\_Type 0x0007.
+
+**ps\_number\_of\_source\_ip** – Specifies how many **ps\_source\_ip\_address(es)** follow. The valid range is 0-32.
+
+**ps\_source\_ip\_address** – The source IPv6 address(es) that the splicer shall use in an IGMP V3 join or an MLD join for the associated multicast **ps\_ip\_address**.
+
+#### **8.5.5 asset\_id\_descriptor( ) field definitions**
+
+The **asset\_id\_descriptor( )** is an implementation of the **splice\_API\_descriptor( )** which shall only be used in the **Splice\_Request** message. This descriptor is intended to be used when the asset playout is being performed by the splicer, but can be used to identify the asset being played also. It is suggested for advertising content that the spot id or other identifier be used rather than a fully qualified name. For long form VOD type content, a full asset name will probably be required. How the server and splicer manage the name format is not specified in this Recommendation.
+
+**Table 8-15 – asset\_id\_descriptor ( )**
+
+| Syntax                       | Bytes | Type   |
+|------------------------------|-------|--------|
+| asset_id_descriptor {        |       |        |
+| <b>Splice_Descriptor_Tag</b> | 1     | uimsbf |
+| <b>Descriptor_Length</b>     | 1     | uimsbf |
+| <b>Splice_Api_Identifier</b> | 4     | uimsbf |
+| <b>Asset_Upid_Type</b>       | 1     | uimsbf |
+| <b>Asset_Upid_Length</b>     | 1     | uimsbf |
+| <b>Asset_Upid( )</b>         |       | uimsbf |
+| }                            |       |        |
+
+**Splice\_Descriptor\_Tag** – 0x06
+
+**Descriptor\_Length** – Variable. The length in bytes of the descriptor following this field.
+
+**Splice\_API\_Identifier** – 0x53415049, ASCII "SAPI".
+
+**Asset\_Upid\_Type** – A value from the segmentation\_upid\_type table (Table 8-6 of [ANSI/SCTE 35]). When the type value from Table 8-6 of [ANSI/SCTE 35] is 0x09 (ADI), the requirements regarding this ADI-related value in section 8.3.3.1 of [ANSI/SCTE 35] shall form a part of this specification.
+
+**Asset\_Upid\_Length** – Length in bytes of the **Asset\_Upid** structure. The maximum value of this field is 245.
+
+**Asset\_Upid( )** – Length and identification from the segmentation\_upid\_type table (Table 8-6 of [ANSI/SCTE 35]). This structure's contents and length are determined by the **Asset\_Upid\_Type** and **Asset\_Upid\_Length** fields. An example is a type of 0x06 for V-ISAN and a length of 12 bytes. This field would then contain the V-ISAN identifier for the content to which this descriptor refers.
+
+#### 8.5.6 create\_feed\_descriptor( ) field definitions
+
+The **create\_feed\_descriptor( )** is an implementation of the **splice\_API\_descriptor( )** which shall only be used in the **Init\_Request** message. This descriptor will give the splicer enough information to create the output SPTS.
+
+The usage of this descriptor shall be as follows:
+
+1. The ad server shall open a new TCP connection to the splicer of the to-be-created feed.
+2. The ad server shall send an **Init\_Request** message with this descriptor on the newly-created TCP connection.
+3. The **ChannelName** field in the **Init\_Request** message shall reflect the name of the newly-created feed.
+4. The splicer shall create the feed according to the **Init\_Request** message. The newly-created feed shall be identical to the feed denoted by **OriginalChannelName** (see below). The identity shall encompass all PID values, types, descriptors, PCR PID and program number within the newly-created feed's PMT and PAT.
+5. The splicer shall send an **Init\_Response** message only after the new feed is created.
+
+**Table 8-16 – create\_feed\_descriptor ( )**
+
+| Syntax                                       | Bytes | Type   |
+|----------------------------------------------|-------|--------|
+| create_feed_descriptor {                     |       |        |
+| <b>Splice_Descriptor_Tag</b>                 | 1     | uimsbf |
+| <b>Descriptor_Length</b>                     | 1     | uimsbf |
+| <b>Splice_API_Identifier</b>                 | 4     | uimsbf |
+| <b>OriginalChannelName</b>                   | 32    | String |
+| <b>Create_Feed_Descriptor_Type</b>           | 1     | uimsbf |
+| if (Create_Feed_Descriptor_Type == 0) {      |       |        |
+| <b>IPV4_Dest_Address</b>                     | 4     | uimsbf |
+| <b>Destination_Port</b>                      | 2     | uimsbf |
+| }                                            |       |        |
+| else if (Create_Feed_Descriptor_Type == 1) { |       |        |
+| <b>IPV6_Dest_Address</b>                     | 16    | uimsbf |
+| <b>Destination_Port</b>                      | 2     | uimsbf |
+| }                                            |       |        |
+| }                                            |       |        |
+
+**Splice\_Descriptor\_Tag** – 0x07
+
+**Descriptor\_Length** – Variable. The length in bytes of the descriptor following this field.
+
+**Splice\_API\_Identifier** – 0x53415049, ASCII "SAPI".
+
+**OriginalChannelName** – The logical name of the output channel used as the template for the newly-created feed. This is a null-terminated string.
+
+**Create\_Feed\_Descriptor\_Type** – This field shall be a 0 to indicate that an IPv4 address is used and shall be a 1 to indicate that an IPv6 address is used.
+
+**IPV4\_Dest\_Address** – The destination IP address for the created output service. This is in the IPv4 format.
+
+**IPV6\_Dest\_Address** – The destination IP address for the created output service. This is in the IPv6 format.
+
+**Destination\_Port** – The destination UDP port for the created output service.
+
+#### **8.5.7 source\_info\_descriptor( ) field definitions**
+
+The source\_info\_descriptor( ) is an implementation of the splice\_API\_descriptor( ) which may be used in the **Cue\_Request** message. This descriptor will give the server enough information to match an insertion feed to the same type, resolution and frame rate as the primary channel. This descriptor shall only be used if the primary channel has one and only one video present.
+
+**Table 8-17 – source\_info\_descriptor ( )**
+
+| Syntax                       | Bytes | Type   |
+|------------------------------|-------|--------|
+| source_info_descriptor {     |       |        |
+| <b>Splice_Descriptor_Tag</b> | 1     | uimsbf |
+| <b>Descriptor_Length</b>     | 1     | uimsbf |
+| <b>Splice_API_Identifier</b> | 4     | uimsbf |
+| <b>StreamType</b>            | 1     | uimsbf |
+| <b>HResolution</b>           | 2     | uimsbf |
+| <b>VResolution</b>           | 2     | uimsbf |
+| <b>frame_rate_code</b>       | 1     | uimsbf |
+| <b>progressive_sequence</b>  | 1     | uimsbf |
+| }                            |       |        |
+
+**Splice\_Descriptor\_Tag** – 0x08
+
+**Descriptor\_Length** – 0x0A
+
+**Splice\_API\_Identifier** – 0x53415049, ASCII "SAPI".
+
+**StreamType** – This number corresponds with the PMT specification found in [ITU-T H.222.0].
+
+**HResolution** – The width in number of pixels of the video pictures.
+
+**VResolution** – The height in number of pixels of the video pictures.
+
+**frame\_rate\_code** – For MPEG-2 video, this parameter shall be coded as per the frame\_rate\_code from Table 6-4 of [ITU-T H.262]. For AVC video, this parameter shall be coded as per the frame\_rate\_code value from Table 6-4 of [ITU-T H.262] that matches the coded frame rate listed in Table 11 of [ANSI/SCTE 128]. Frame rate codes are shown in Appendix III.
+
+**progressive\_sequence** – For MPEG-2 video, this parameter shall be coded as per clause 6.3.5 of [ITU-T H.262]. For AVC video, this parameter shall be set to '1' when the letter 'P' in Table 11 of [ANSI/SCTE 128] is listed with the corresponding frame rate; otherwise, this parameter shall be set to '0'.
+
+# 9 Time synchronization
+
+Time synchronization is required due to the communication of time between the server and the splicer. The delay on a TCP/IP message is somewhat unpredictable and is affected by other machines on the network. By having the machines synchronized, time can be communicated between the two machines without concern for normal network delays keeping the splicing very accurate. One possible method is to use a network time protocol (NTP) to keep the server and the splicer in synchronization. It is likely that servers already keep some time synchronization, and thus could provide the NTP service and the splicer could be an NTP client. A network common host system NTP server could also be used since this also typically exists in a cable headend that has a network infrastructure.
+
+The time synchronization system must be able to keep the splicer and server within  $\pm 15$  ms of each other. The system may use the **Alive\_Request/Alive\_Response** messages to detect if the two devices have proper synchronization and to alert the operator if synchronization is lost.
+
+The bit stream representing the primary channel is subject to various delays, which may include upstream splicing, satellite links and other transmission and conditioning processes. These delays may total from milliseconds to seconds. However, these delays do not affect the accuracy of a cue
+
+message embedded in the primary channel. The cue message uses the PCR to indicate the correct time of insertion so that it retains its original accuracy relative to the content.
+
+The server providing the insertion channel content knows only about clock time (UTC) and the insertion windows with which it has been programmed are relative to clock time. However, it depends on the splicer to tell it the exact moment that it is to begin streaming that content.
+
+When the splicer receives the program bit stream, all delays to that stream have occurred. The splicer can take the PCR and relate it to the clock time, then send a message to the server that specifies the exact UTC at which it must begin streaming. The insertion channel from the server now arrives at the splicer exactly synchronized with the primary channel, and a perfect splice can be achieved. Any additional delays that occur within the splicer are irrelevant, since the input bit streams were synchronized.
+
+If all parts of a facility do not use UTC time, that is, parts use GPS-based time, then all splicing system implementations should consider the conversion from GPS-based time of day to UTC and consistently include or ignore the GPS to UTC offset in computing times.
+
+# 10 System timing
+
+### 10.1 DPI splice signal flow
+
+Figures 10-1 and 10-2 convey specific details regarding the usage and ordering of the various messages allowed by this API. The actual usage of API messages may not be limited to these examples.
+
+![Sequence diagram of DPI splice signal flow between Splicer and Server.](9f862801bce82634d3b5a1e0a195a799_img.jpg)
+
+The diagram illustrates the signal flow between a Splicer and a Server for a single event splice. The sequence of messages is as follows:
+
+- 1) The Splicer sends a **CRM** (Cue\_Request Message) to the Server.
+- 2) The Server responds with the **CRespM** (Cue\_Response Message).
+- 3) At least 3 seconds prior to the intended splice time, the Server sends the **SRM** (Splice\_Request Message) to the Splicer.
+- 4) The Splicer responds with the **SRespM** (Splice\_Response Message).
+- 5) Shortly after the insertion has begun, the Splicer sends a **SCM** (SpliceComplete\_Response Message).
+- 6) The Splicer sends another **SCM** (SpliceComplete\_Response Message) after the insertion has completed.
+
+The timeline is divided into three phases: **Splice In** (before the start of the insertion), **Insertion In Progress** (the period of the splice), and **Splice Out** (after the insertion has completed). The first four messages occur during the **Splice In** phase. The fifth message occurs at the start of the **Insertion In Progress** phase. The sixth message occurs during the **Splice Out** phase.
+
+Sequence diagram of DPI splice signal flow between Splicer and Server.
+
+Figure 10-1 – Single event splice
+
+![Sequence diagram showing multiple event splice initiation between a Splicer and a Server. The diagram includes message exchanges (CRM, CRespM, SRM, SRespM, SCM) and splice events (Splice In, Insertion In Progress, Splice Out).](5eb69662cc4fa7d0d49b4eb22951c204_img.jpg)
+
+The diagram illustrates the interaction between a Splicer and a Server for multiple event splices. The sequence of messages is as follows:
+
+- 1) CRM: Splicer to Server
+- 2) CRespM: Server to Splicer
+- 3) SRM1: Server to Splicer
+- 3a) SRespM1: Splicer to Server
+- 4) SRM2: Server to Splicer
+- 4a) SRespM2: Splicer to Server
+- 5) SRM3: Server to Splicer
+- 5a) SRespM3: Splicer to Server
+- 3b) SCM1 (in): Splicer to Server (during first splice)
+- 4b) SCM2 (in) and 4b) SCM1 (out): Splicer to Server (during second splice)
+- 5b) SCM3 (in) and 5b) SCM2 (out): Splicer to Server (during third splice)
+- 6) SCM3 (out): Splicer to Server (after third splice)
+
+Splice events are indicated by horizontal lines and labels:
+
+- Splice In**: Occurs after message 5a) SRespM3.
+- Insertion In Progress**: Occurs during the splice events (3b, 4b, 5b).
+- Splice Out**: Occurs before message 6) SCM3 (out).
+
+Sequence diagram showing multiple event splice initiation between a Splicer and a Server. The diagram includes message exchanges (CRM, CRespM, SRM, SRespM, SCM) and splice events (Splice In, Insertion In Progress, Splice Out).
+
+1) The Splicer sends a Cue\_Request Message to the Server shortly after the SCTE 35 message is received by the Splicer in the Primary Channel.
+
+2) The Server responds with the Cue\_Response Message.
+
+3) At least 3 seconds prior to the intended splice time, the Server sends the first Splice\_Request Message to the Splicer. (3a) The Splicer will respond with the first Splice\_Response Message. (3b) Once this first splice is made the Splicer will send the server the first SpliceComplete\_Response Message.
+
+4) For the next splice, the Splicer must receive the next Splice\_Request Message anywhere from just after the first Splice\_Request message up to 3 seconds prior to its designated splice. (4a) The Splicer responds with the second Splice\_Response Message. (4b) At the completion of the first splice the Splicer will send two SpliceComplete\_Response messages denoting the end of the first splice and the beginning of the second splice.
+
+5) For the third splice, the Splicer must receive the next Splice\_Request Message anywhere from just after the first and second Splice\_Request message up to 3 seconds prior to its designated splice. (5a) The Splicer responds with the second Splice\_Response Message. (5b) At the completion of the first splice the Splicer will send two SpliceComplete\_Response messages denoting the end of the second splice and the beginning of the third splice.
+
+6) Shortly after the third splice completes, the Splicer sends another SpliceComplete\_Response Message.
+
+Figure 10-2 – Multiple event splice
+
+### 10.2 DPI splice initiation timeline
+
+Figure 10-3 gives a timing example of the events leading up to the beginning of a program (or advertisement) insertion. Times in a real situation may vary from the timing shown in this figure. The interval of time shown is applicable to the discussion of priority arbitration as presented in clause 6.2. Operation in conjunction with ANSI/SCTE 35 cueing messages is also shown.
+
+In the figure, bold black lines indicate the flow of MPEG information on the primary channel line and on the insertion channel line. Thin black lines indicate that MPEG information is either not flowing at that moment or is unimportant (i.e., not selected to appear at the output channel).
+
+![DPI splice initiation timeline diagram showing Primary Channel, TCP/IP API Traffic, and Insertion Channel over NTP Time from -1.00 Sec to 3.50 Sec. The diagram illustrates the sequence of events for a DPI splice, including Cue Request/Response, Splice Request/Response, and Splice Complete Response, with various timing parameters like DTS, PTS, and VBV Delay.](32f80b2d70752613b6577797811f3a95_img.jpg)
+
+The diagram illustrates the DPI splice initiation timeline across three vertical axes representing different data streams over NTP Time from -1.00 Sec to 3.50 Sec.
+
+- Primary Channel:** The main data stream. At -1.00 Sec, a **DVS/253 Cue Message** is sent. At 0.00 Sec, a **Splice Request** is sent. At approximately 2.50 Sec, the **Splice Point in Stream** occurs, followed by **DTS**, **VBV Delay (variable)**, and **PTS** markers.
+- TCP/IP API Traffic:** The control plane. At -1.00 Sec, a **Cue Request** is sent. At 0.00 Sec, a **Splice Request** is sent. At 3.00 Sec, a **Splice Complete Response** is received.
+- Insertion Channel:** The new data stream. At -0.25 Sec, a **PAT/PMT Change** occurs. At 0.00 Sec, the new stream begins. At 3.00 Sec, the **Splice Complete Response** is received.
+
+Key timing intervals and parameters shown:
+
+- 3 Sec:** Duration from 0.00 Sec to 3.00 Sec.
+- 600ms:** Duration from 2.40 Sec to 3.00 Sec.
+- 300ms:** Duration from 2.70 Sec to 3.00 Sec.
+- 200ms:** Duration from -0.20 Sec to 0.00 Sec.
+
+DPI splice initiation timeline diagram showing Primary Channel, TCP/IP API Traffic, and Insertion Channel over NTP Time from -1.00 Sec to 3.50 Sec. The diagram illustrates the sequence of events for a DPI splice, including Cue Request/Response, Splice Request/Response, and Splice Complete Response, with various timing parameters like DTS, PTS, and VBV Delay.
+
+Figure 10-3 – DPI splice initiation timeline
+
+## Appendix I
+
+### Result codes
+
+(This appendix does not form an integral part of this Recommendation.)
+
+See the table on the following pages.
+
+| Result | Result Name                        | Description                                                                                                                                                         | Response Message                                                                |
+|--------|------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------|
+| 100    | Successful Response                |                                                                                                                                                                     | All                                                                             |
+| 101    | Unknown Failure                    |                                                                                                                                                                     | All                                                                             |
+| 102    | Invalid Version                    | Server and splicer are using different versions of this API.                                                                                                        | <b>Init_Response</b>                                                            |
+| 103    | Access Denied                      | Possible licence problem.                                                                                                                                           | <b>Init_Response</b><br><b>Splice_Response</b>                                  |
+| 104    | Invalid/Unknown <b>ChannelName</b> | Possible configuration error.                                                                                                                                       | <b>Init_Response</b>                                                            |
+| 105    | Invalid Physical Connection        | Possible configuration error.                                                                                                                                       | <b>Init_Response</b>                                                            |
+| 106    | No Configuration Found             | Splicer unable to determine the configuration for this connection.                                                                                                  | <b>GetConfig_Response</b>                                                       |
+| 107    | Invalid Configuration              | One or more of the parameters in the configuration for this connection is invalid.                                                                                  | <b>GetConfig_Response</b>                                                       |
+| 108    | Splice Failed – Unknown Failure    |                                                                                                                                                                     | <b>SpliceComplete_Response</b>                                                  |
+| 109    | Splice Collision                   | A higher or same priority is already set to splice.                                                                                                                 | <b>Splice_Response</b><br><b>SpliceComplete_Response</b>                        |
+| 110    | No Insertion Channel Found         | This error shall be returned if the insertion channel is missing.                                                                                                   | <b>SpliceComplete_Response</b>                                                  |
+| 111    | No Primary Channel Found           | This result shall be returned if the primary channel is missing at the splice-in or splice-out times.                                                               | <b>SpliceComplete_Response</b>                                                  |
+| 112    | <b>Splice_Request</b> Was Too Late | The <b>Splice_Request</b> message was not received early enough (3 seconds) for the splicer to initiate the splice.                                                 | <b>Splice_Response</b>                                                          |
+| 113    | No Splice Point Was Found          | The splicer was unable to find a valid point to splice in to the Primary Channel.                                                                                   | <b>SpliceComplete_Response</b>                                                  |
+| 114    | Splice Queue Full                  | Too many outstanding <b>Splice_Request</b> messages.                                                                                                                | <b>Splice_Response</b>                                                          |
+| 115    | Session Playback Suspect           | Splicer has detected video or audio discrepancies that may have affected playback.                                                                                  | <b>SpliceComplete_Response</b>                                                  |
+| 116    | Insertion Aborted                  | An <b>Abort_Request</b> message caused a splice-out.                                                                                                                | <b>SpliceComplete_Response</b>                                                  |
+| 117    | Invalid Cue Message                | The splicer or server could not parse the cue message.                                                                                                              | <b>General_Response</b><br><b>Cue_Response</b>                                  |
+| 118    | Splicing Device Does Not Exist     | <b>SplicerName</b> was not found.                                                                                                                                   | <b>Init_Response</b>                                                            |
+| 119    | <b>Init_Request</b> Refused        | The splicer refuses to allow the server to connect.                                                                                                                 | <b>Init_Response</b>                                                            |
+| 120    | Unknown <b>MessageID</b>           | Use <b>Splicing_API_Message</b> to send response to requester. Echo back the unknown <b>MessageID</b> .                                                             | All                                                                             |
+| 121    | Invalid <b>SessionID</b>           | The Splicer has no knowledge of the specified <b>SessionID</b> .                                                                                                    | <b>Splice_Response</b><br><b>Abort_Response</b><br><b>ExtendedData_Response</b> |
+| 122    | Session Did Not Complete           | Splicer was not able to play the complete duration. This includes the case where the server did not supply the sufficient content.                                  | <b>SpliceComplete_Response</b>                                                  |
+| 123    | Invalid Request Message data( )    | Splicer or server was not able to parse a field in the request message successfully. The invalid field position is returned in the <b>Result_Extension</b> field of | All                                                                             |
+
+|     |                                 |                                                                                                                                                                                                                                                       |                                                          |
+|-----|---------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------|
+| 124 | Descriptor Not Implemented      | The splicer does not currently understand or implement the requested descriptor.                                                                                                                                                                      | Responses to all messages that allow descriptors.        |
+| 125 | Channel Override                | This result code is used to indicate to the currently playing insertion that it has been overridden with a splice-out status or has been re-entered with a Splice_ in status.                                                                         | <b>SpliceComplete_Response</b>                           |
+| 126 | Insertion Channel Started Early | This error may be issued if the insertion channel started early and the splicer was not able to determine the correct start of the insertion stream.                                                                                                  | <b>SpliceComplete_Response</b>                           |
+| 127 | Playback Rate Below Threshold   | See playback_descriptor( ) for details.                                                                                                                                                                                                               | <b>SpliceComplete_Response</b>                           |
+| 128 | PMT changed                     | This is used to indicate to the server that the PMT for this primary channel has changed.                                                                                                                                                             | <b>General_Response</b>                                  |
+| 129 | Invalid message size            | The message was not the correct length as determined by this specification.                                                                                                                                                                           | All                                                      |
+| 130 | Invalid message syntax          | Fields defined by this specification are not within the valid range.                                                                                                                                                                                  | All                                                      |
+| 131 | Port Collision Error            | The splicer was not able to utilize the specified IP:port combination requested. The combination is either in use or not valid on this splicer.                                                                                                       | Init_Response                                            |
+| 132 | Splice Failed – EAS active      | This error shall be returned if the emergency alert system is active.                                                                                                                                                                                 | <b>SpliceComplete_Response</b><br><b>Splice_Response</b> |
+| 133 | Insertion Component Not Found   | One or more of the insertion stream components was not found. The result extension has the stream type of the first missing component.                                                                                                                | <b>SpliceComplete_Response</b>                           |
+| 134 | Resources Not Available         | Returned by a splicer which was requested to provide a service for which it had no resources. i.e. the create_feed_descriptor() in an Init_Request message could not be honoured by the splicer due to the splicer's output B/W being fully occupied. | Init_Response                                            |
+
+|                                                                            |                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                 |
+|----------------------------------------------------------------------------|--------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------|
+| 135                                                                        | Component Mismatch | <p>This code MAY be returned by a splicer when the Splice_Request fails to define an insertion channel component needed to match a primary channel component.</p> <p>Examples:</p> <ol style="list-style-type: none"> <li>1. The primary channel contains an AC-3 audio component, but the Splice_Request defines only an MPEG2 audio component.</li> <li>2. The primary channel contains an AVC video component, but the Splice_Request defines only an MPEG-2 video component.</li> </ol> | Splice_Response |
+| Note: All result codes may be used in the <b>General_Response</b> message. |                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |                 |
+
+## Appendix II
+
+### Example use of Logical\_Multiplex type 0x0006 and the port\_selection\_descriptor( )
+
+(This appendix does not form an integral part of this Recommendation.)
+
+### II.1 Informative example 1
+
+The following example illustrates the use of multiple Splice\_Requests in sequence and the incrementing of port numbers between the subsequent requests when port\_selection\_descriptors are not present. (See clause 8.2)
+
+All ports are statically set up on the Init\_Request.
+
+Base IP:Port = 192.168.134.9:2000
+
+Number of ports = 4
+
+The following events occur sequentially in time during a single avail.
+
+- 1) Splice\_Request with time( ) set, server uses port 2000
+- 2) Splice\_Request with PriorSession, server uses port 2001
+- 3) Splice\_Request with PriorSession, server uses port 2002
+- 4) Splice\_Request with PriorSession, server uses port 2003
+- 5) Splice\_Request with PriorSession, server uses port 2000
+- 6) Splice\_Request with PriorSession, port\_selection\_descriptor port = 2000, server uses port 2000
+- 7) Splice\_Request with PriorSession, port\_selection\_descriptor port = 2003, server uses port 2003.
+
+Next avail
+
+- 1) Splice\_Request with time( ) set, server uses port 2000.
+
+### II.2 Informative example 2
+
+Use of port\_selection\_descriptor( ) to dynamically set up a port. Base port is established statically in the Init\_Request message.
+
+Base IP:Port = 192.168.134.9:3000
+
+Number of ports = 1
+
+The following events occur sequentially in time during a single avail.
+
+- 1) Splice\_Request with time( ) set, server uses port 3000
+- 2) Splice\_Request with PriorSession, port\_selection\_descriptor IP = 192.168.134.9 port = 2010, server sets up and uses 192.168.134.9:2010
+- 3) Splice\_Request with PriorSession, port\_selection\_descriptor IP = 239.192.0.2 port = 2010, server sets up and uses 239.192.0.2:2010.
+
+Next avail
+
+- 1) Splice\_Request with time( ) set, server uses port 2000.
+
+## Appendix III
+
+### Frame rate codes
+
+(This appendix does not form an integral part of this Recommendation.)
+
+**Table III.1 – Frame rate codes**
+
+| Frame rate (Hz)      | frame_rate_code | AVC time_scale | AVC num_units_in_tick |
+|----------------------|-----------------|----------------|-----------------------|
+| 24/1.001 (23.976...) | '0001'          | 48000          | 1001                  |
+| 24                   | '0010'          | 48             | 1                     |
+| 30/1.001 (29.97...)  | '0100'          | 60000          | 1001                  |
+| 30                   | '0101'          | 60             | 1                     |
+| 60/1.001 (59.94...)  | '0111'          | 120000         | 1001                  |
+| 60                   | '1000'          | 120            | 1                     |
+
+## Bibliography
+
+- [b-ANSI/SCTE 67] ANSI/SCTE 67 (2010), *Recommended Practice for SCTE 35 Digital Program Insertion Cueing Message for Cable*. <[http://www.scte.org/documents/pdf/Standards/ANSI\\_SCTE%2067%202010.pdf](http://www.scte.org/documents/pdf/Standards/ANSI_SCTE%2067%202010.pdf)>
+- [b-IETF RFC 3810] IETF RFC 3810 (2004), *Multicast Listener Discovery Version 2 (MLDv2) for IPv6*. <<http://tools.ietf.org/html/rfc3810>>
+- [Cable Television Laboratories] Cable Television Laboratories (1997), *Cable Advertising*. White Paper. Louisville, CO, USA.
+- [Kar, Narasimhan, Prodan] Kar, M. Narasimhan S., and Prodan R. (2000), *Local Commercial Insertion in the Digital Headend*, In: Proceedings of the NCTA 2000 Conference. New Orleans, 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.287**
+
+(01/2014)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Digital transmission of television signals
+
+---
+
+**Automation system to compression system  
+communications application program interface**
+
+Recommendation ITU-T J.287
+
+
+
+# Recommendation ITU-T J.287
+
+## Automation system to compression system communications application program interface
+
+## Summary
+
+Recommendation ITU-T J.287 defines the communications applications program interface between an advanced advertising automation system and the associated stream compression system that will insert digital cueing message private sections into the outgoing transport stream.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T J.287    | 2014-01-13 | 9           | <a href="http://handle.itu.int/11.1002/1000/12103">11.1002/1000/12103</a> |
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+# 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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 .....                                                  | 1    |
+| 3.1 Terms defined elsewhere .....                                    | 1    |
+| 3.2 Terms defined in this Recommendation.....                        | 1    |
+| 4 Abbreviations and acronyms .....                                   | 4    |
+| 5 Conventions .....                                                  | 5    |
+| 6 Overview.....                                                      | 5    |
+| 7 Data communications .....                                          | 7    |
+| 7.1 Concerning data communications (informative) .....               | 7    |
+| 7.2 Data communications requirements for this API (normative) .....  | 8    |
+| 7.3 Conveyance quality of service considerations (informative) ..... | 8    |
+| 7.4 Unidirectional system considerations (informative) .....         | 9    |
+| 7.5 Proxy devices (normative).....                                   | 9    |
+| 8 Message formats .....                                              | 9    |
+| 8.1 Terminology (informative).....                                   | 9    |
+| 8.2 Message structures (normative).....                              | 10   |
+| 8.3 Operation types (normative).....                                 | 15   |
+| 8.4 Conventions and requirements .....                               | 21   |
+| 9 Automation system to injector communication.....                   | 22   |
+| 9.1 Initialization.....                                              | 22   |
+| 9.2 Alive ("Heartbeat") communications .....                         | 23   |
+| 9.3 Splice requests .....                                            | 24   |
+| 9.4 Encryption support (normative) .....                             | 28   |
+| 9.5 Component mode support.....                                      | 31   |
+| 9.6 Response messages.....                                           | 32   |
+| 9.7 ITU-T J.181 splice_schedule() support requests .....             | 34   |
+| 9.8 Miscellaneous requests .....                                     | 38   |
+| 10 PAMS to the automation system communications .....                | 44   |
+| 10.1 System design philosophy .....                                  | 44   |
+| 10.2 PAMS functionality.....                                         | 45   |
+| 10.3 Service continuity .....                                        | 46   |
+| 10.4 System initialization messages .....                            | 46   |
+| 10.5 Injector service notification .....                             | 48   |
+| 10.6 Failure notification messages (device or communications) .....  | 50   |
+| 10.7 PAMS to AS permanent "link alive" messages .....                | 52   |
+| 10.8 PAMS to AS common elements.....                                 | 52   |
+
+|              | Page                                                             |    |
+|--------------|------------------------------------------------------------------|----|
+| 11           | PAMS to injector communications (informative) .....              | 53 |
+| 11.1         | The PAMS implementation .....                                    | 53 |
+| 11.2         | Injector provisioning .....                                      | 53 |
+| 11.3         | PAMS structure .....                                             | 54 |
+| 11.4         | Support of multiple DPI PIDs .....                               | 54 |
+| 12           | Common elements .....                                            | 54 |
+| 12.1         | Values of splice_event_id used in this interface .....           | 54 |
+| 12.2         | Values of unique_program_id used in this interface .....         | 54 |
+| 12.3         | Minimum pre-roll time supported by this interface .....          | 54 |
+| 12.4         | time() definition .....                                          | 55 |
+| 12.5         | timestamp() definition .....                                     | 55 |
+| 13           | System architecture and provisioning (informative) .....         | 57 |
+| 13.1         | One-way protocol – automation system to injector .....           | 57 |
+| 13.2         | Two-way protocol – automation system to injector only .....      | 63 |
+| 13.3         | Two-way protocol – automation system to injector with PAMS ..... | 76 |
+| 14           | Result codes (normative) .....                                   | 83 |
+| Annex A      | – TCP/IP conveyance .....                                        | 87 |
+| Annex B      | – ANSI/TIA/EIA-232-F conveyance .....                            | 88 |
+| B.1          | The basic link layer syntax .....                                | 88 |
+| B.2          | The escape sequence .....                                        | 89 |
+| Annex C      | – Digital video system conveyance .....                          | 90 |
+| Annex D      | – Analogue video system conveyance .....                         | 91 |
+| Bibliography | .....                                                            | 92 |
+
+# Recommendation ITU-T J.287
+
+## Automation system to compression system communications application program interface
+
+# 1 Scope
+
+This Recommendation defines the communications API between an automation system and the associated compression system that will insert ITU-T J.181 private sections into the outgoing transport stream. This Recommendation serves as a companion to both [ITU-T J.181] and [ITU-T J.280].
+
+# 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 H.222.0] Recommendation ITU-T H.222.0 (2012), *Information technology – Generic coding of moving pictures and associated audio information: Systems*.
+- [ITU-T J.181] Recommendation ITU-T J.181 (2014), *Digital program insertion cueing message for cable television systems*.
+- [ITU-T J.280] Recommendation ITU-T J.280 (2013), *Digital program insertion: Splicing application program interface*.
+- [SMPTE ST 2010] SMPTE ST 2010 (2008), *Vertical Ancillary Data Mapping of ANSI/SCTE 104 Messages*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 analogue cue tone** [ITU-T J.181]: In an analogue system, a signal that is usually either a sequence of DTMF tones or a contact closure that denotes to ad insertion equipment that an advertisement avail is about to begin or end.
+
+**3.1.2 break** [ITU-T J.181]: An avail or an actual insertion in progress.
+
+**3.1.3 viewing event** [ITU-T J.181]: A television programme or a span of compressed material within a service as opposed to a splice event, which is a point in time.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 API connection**: A communications connection between an automation system and an injector for transferring API messages.
+
+**3.2.2 automation system**: A control system for a program origination facility which controls operation of the production facilities and devices.
+
+- 3.2.3 avail:** Time space provided to cable operators by cable programming services during a programme for use by the CATV operator; the time is usually sold to local advertisers or used for channel self-promotion.
+- 3.2.4 basic:** A category of request or response operation supported by this API. See clause 8.3.
+- 3.2.5 backoff:** A mechanism, commonly used in data communications, to randomize the interval between retries.
+- 3.2.6 Bslbf:** Bit string, left bit first, where "left" is the order in which bit strings are written in the Recommendation. Bit strings are written as a string of 1s and 0s within single quote marks, e.g., '1000 0001'. Blanks within a bit string are for ease of reading and have no significance. (See [ITU-T H.222.0].)
+- 3.2.7 command:** A single directive from the automation system to the compression system. A command is always carried within a multiple\_operation message. This term is also used to specify specific ITU-T J.181 commands.
+- 3.2.8 component splice mode:** A mode of the splice\_info\_section whereby the program\_splice\_flag is set to '0' and indicates that each PID/component that is intended to be spliced will be listed separately by the syntax that follows. Components not listed in the splice\_info\_section are not to be spliced.
+- 3.2.9 control:** A category of request operation supported by this API. See clause 8.3.
+- 3.2.10 control word:** A multiple key value used by the encryption mechanisms specified in [ITU-T J.181].
+- 3.2.11 cueing message:** See splice\_info\_section. A term used in [ITU-T J.181]; a "Cueing Message" is a Cueing Section in this document.
+- 3.2.12 deferred processing mode:** Processing of a multiple\_operation\_message() when the value of time\_type within timestamp() is non-zero.
+- 3.2.13 digital cue tone:** Widely used term to refer to an ITU-T J.181 splice\_info\_section().
+- 3.2.14 DPI cue message:** See splice\_info\_section. A term used in [ITU-T J.181]; a "DPI Cue Message" is a splice\_info\_section in this document.
+- 3.2.15 DPI PID:** A single PID carrying ITU-T J.181 splice\_info\_sections.
+- 3.2.16 event:** A splice event or a viewing event as defined below.
+- 3.2.17 GPI:** A general purpose interface which is commonly used to source or sink contact closures in video facilities.
+- 3.2.18 HANC:** Horizontal ancillary data space in digital video streams.
+- 3.2.19 HD-SDI:** Abbreviation for high definition serial digital interface (see [b-SMPTE ST 292-1]).
+- 3.2.20 immediate mode:** Processing of a multiple\_operation\_message() when the value of time\_type within timestamp() is 0.
+- 3.2.21 injector:** A device or combination of devices within the DCS capable of converting ITU-T J.287 message data into an ITU-T J.181 splice\_info\_section(), including a program-specific PCR splice time value, if necessary, and multiplexing the resulting section data along with the other program components into the eventual MPEG SPTS or MPTS.
+- 3.2.22 injector instance:** A specific instance of an injector, constrained to place a single DPI PID into a single MPEG program in a single transport stream.
+- 3.2.23 in point:** A point in the stream, suitable for entry, that lies on an access unit boundary.
+
+- 3.2.24 long form insertion:** Refers to insertions of material with a duration generally greater than 10 minutes, i.e., program length material.
+- 3.2.25 message:** In the context of this document a message is a single communication between the automation system and the compression system or between the automation system and the PAMS. A message may contain one or more operations.
+- 3.2.26 normal:** A category of request operation supported by this API. See clause 8.3.
+- 3.2.27 out point:** A point in the stream, suitable for exit, that lies on an access unit boundary.
+- 3.2.28 PID stream:** A stream of packets with the same PID within a transport stream.
+- 3.2.29 port:** See "socket". Refers to a bit-field defined in a TCP header. May also refer to a specific physical connector mounted on a device.
+- 3.2.30 presentation time:** The time that a presentation unit is presented in the system target decoder.
+- 3.2.31 program:** A collection of video, audio and data PID streams which share a common program number within a SPTS or MPTS.
+- 3.2.32 registration descriptor:** An MPEG-2 ([ITU-T H.222.0]) construct to uniquely and unambiguously identify formats of private data. As used in this context, it is carried in the PMT of a program to indicate the program's compliance with [ITU-T J.181]. (See clause 2.6.8 of [ITU-T H.222.0].)
+- 3.2.33 request:** A single directive, from either the automation system, the injector or the PAMS, to another portion of the overall system. "Request" and "Command" are used interchangeably. A request is always carried within a message. A request is normally answered by a response message.
+- 3.2.34 reserved:** The term "reserved", when used in the clauses defining the coded bit stream, indicates that the value may be used in the future for extensions to the Recommendation. Unless otherwise specified in this Recommendation, all reserved bits shall be set to '1'.
+- 3.2.35 response:** A reply message to a request directive from the other portion of the system. Responses are made by the automation system, the compression system, and the PAMS in reply to requests. A response is always carried within a single\_operation message.
+- 3.2.36 section:** A private\_section structure as defined by [ITU-T H.222.0] and (in this case) [ITU-T J.181]. As used here, the term is usually "splice\_info\_section". See clause 6.2 of [ITU-T J.181] and clause 2.4.4.10 of [ITU-T H.222.0].
+- 3.2.37 short form insertion:** Refers to insertions of material with a duration of generally less than 10 minutes, i.e., advertising or promotional material. At the time of writing, it is the primary use of DPI technology.
+- 3.2.38 simple profile:** A defined subset of the automation to injector messages in this API which supports all basic splicing functionality while excluding schedules, encryption and component mode. An implementer may choose to support only the "Simple Profile" or features beyond it. The implementer can then describe their implementation in common terms (for example "Simple Profile plus encryption").
+- 3.2.39 socket:** A TCP/IP mechanism used for connection-oriented communications. Sometimes it is also called "port" in an interchangeable manner.
+- 3.2.40 spot:** Term for the content of an advertisement, and sometimes also used to refer to an avail.
+- 3.2.41 splice event:** An opportunity to splice one or more PID streams.
+- 3.2.42 splice\_info\_section:** Basic ITU-T J.181 structure for carrying DPI commands in a TS to downstream equipment.
+
+**3.2.43 splice immediate mode:** A mode of the splice\_info\_section whereby the splicing device shall choose the nearest opportunity in the stream, relative to the splice\_info\_table, to splice. When not in this mode, the splice\_info\_section gives a "PTS\_time", which is a presentation time, for the intended splicing moment.
+
+**3.2.44 splice point:** A point in a PID stream that is either an out point or an in point.
+
+**3.2.45 supplemental:** A category of request operation supported by this API. See clause 8.3.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|        |                                                          |
+|--------|----------------------------------------------------------|
+| API    | Application Program Interface                            |
+| AS     | Automation System                                        |
+| BER    | Bit-Error Rate                                           |
+| CA     | Conditional Access                                       |
+| CRC    | Cyclic Redundancy Check                                  |
+| CW     | Control Word                                             |
+| dB     | Decibel                                                  |
+| DCS    | Digital Compression System                               |
+| DES    | Data Encryption Standard                                 |
+| DPI    | Digital Program Insertion                                |
+| GPI    | General Purpose Interface                                |
+| HANC   | Horizontal Ancillary data space in digital video streams |
+| HD-SDI | High Definition – Serial Digital Interface               |
+| IJ     | Injector                                                 |
+| MPTS   | Multi-Program Transport Stream                           |
+| MSB    | Most Significant Bit                                     |
+| NTP    | Network Time Protocol                                    |
+| OSI    | Open Systems Interconnection                             |
+| PAMS   | Provisioning and Alarm Management System                 |
+| PID    | Packet identifier                                        |
+| PMT    | Program Map Table                                        |
+| PPP    | Point-to-Point Protocol                                  |
+| PTS    | Presentation Time Stamp                                  |
+| SDI    | Serial Digital Interface                                 |
+| SNR    | Signal to Noise Ratio.                                   |
+| SNTP   | Simple Network Time Protocol                             |
+| SPTS   | Single Program Transport Stream                          |
+| TS     | Transport Stream                                         |
+| uimsbf | Unsigned integer, most significant bit first.            |
+
+|      |                                                        |
+|------|--------------------------------------------------------|
+| UTC  | Coordinated Universal Time                             |
+| VANC | Vertical Ancillary data space in digital video streams |
+| VITC | Vertical Interval Time Code                            |
+| WST  | World System Teletext                                  |
+
+# 5 Conventions
+
+None.
+
+# 6 Overview
+
+The block diagrams in Figures 6-1 and 6-2 are based on Figure 6-1 of [ITU-T J.280]. They show a single automation system, a single injector and a single splicer. In reality, the injector is part of an overall digital compression system (DCS), which includes several other injectors (for other channels), multiplexers and usually conditional access. Typically, this system will include redundancy, to prevent a single device failure from forcing the system offline. Splice\_info\_section injection may actually be done by encoders, multiplexers or other devices. As a result, the injecting device will be referred to in the rest of this document simply as an "injector".
+
+All of these components are under the watch of a master provisioning and alarm management system, or "PAMS". The primary task of the PAMS is to monitor device health within the DCS, to notify human operators of any failures, and to switch redundant units into service as directed by the operator. The secondary task of the PAMS is to provide provisioning for the equipment contained within the DCS. Provisioning is usually defined as setting service parameters for each device. The automation system, the digital compression system and the PAMS are frequently located at the program origination facility, sometimes referred to as the "uplink" facility.
+
+Note that TCP/IP networks for use with this Recommendation are intended as strictly private, closed networks for the use of the automation, compression and splicing systems. As a result, latency is not expected to be a major factor in system design. None of these should be connected to either the commercial Internet or any other LAN or WAN without appropriate routing and firewall systems in place to ensure exclusion of intrusive traffic, either planned (malicious) or unplanned (accidental).
+
+Latency in a moderately trafficked TCP/IP network should be much less than 1 video frame time (33.37 ms for 30/1.001 Hz systems and 40 ms for 25 Hz systems). As a result, the use of time-stamping is not mandatory, and thus is an optional portion of this API.
+
+The following two end-to-end system block diagrams are intended as informative high-level overviews of the components of systems compliant with this Recommendation. They illustrate both bidirectional (TCP/IP or serial) data communications, as well as unidirectional (video conveyed or serial) data communications.
+
+Actual system architectures are discussed in clause 13.
+
+In addition to TCP/IP, this API also supports data communications through other physical layers, such as unidirectional or bidirectional serial (ANSI/TIA/EIA-232-F) or unidirectional serial digital video (VANC). SMPTE has standardized carriage in VANC in [SMPTE ST 2010].
+
+![ITU-T J.181 overall system block diagram with bidirectional data communications. The diagram is divided into three main sections: 'Located at origination facility', 'Located at uplink (or origination facility)', and 'Located at cable head-end'. The first section includes Video/Audio sources, an Automation system (with TCP/IP socket), and a Human operator. The second section includes an Injector (with TCP/IP socket and MPEG-2 TS), a Network cloud, and a PAMS (with TCP/IP socket) connected to a Human operator. The third section includes a Digital compression system (DCS) with a Splicer, Primary and Insertion multiplexes, and an Output multiplex, connected to a Server via an SCTE 30 network connection. Arrows indicate the flow of data, including baseband video/audio, DPI trigger messages, AS to PAMS provisioning messages, and provisioning and alarms.](d4af765160d04ecef538e5066006dc77_img.jpg)
+
+The diagram illustrates the ITU-T J.181 overall system architecture, organized into three functional zones:
+
+- Located at origination facility:**
+  - Video/Audio sources** provide baseband video/audio to the **Injector** and send **DPI trigger messages** (carried by bi-directional data communications (TCP/IP or serial)) to the **Automation system**.
+  - Automation system** (containing a **TCP/IP socket**) provides **Automation control** to the sources and is connected to a **Human operator**.
+- Located at uplink (or origination facility):**
+  - Injector** (containing a **TCP/IP socket** and **MPEG-2 TS**) receives baseband video/audio and sends a **Transmission path** to the **Network interface or demodulator**.
+  - Network** cloud connects the **Automation system** and the **Injector** to the **PAMS**.
+  - AS to PAMS provisioning and redundancy messages** (carried by bi-directional data communications (TCP/IP or serial)) are sent from the **Automation system** to the **PAMS**.
+  - PAMS** (containing a **TCP/IP socket**) is connected to a **Human operator** and exchanges **Provisioning and alarms** with the **Injector**.
+- Located at cable head-end:**
+  - Network interface or demodulator** receives the transmission path and sends **Primary multiplex** and **Insertion multiplex** signals to the **Splicer**.
+  - Splicer** (containing a **TCP/IP socket**) combines the signals into an **Output channel**, which results in the **Output multiplex**.
+  - Server** is connected to the **Splicer** via an **SCTE 30 network connection**.
+
+ITU-T J.181 overall system block diagram with bidirectional data communications. The diagram is divided into three main sections: 'Located at origination facility', 'Located at uplink (or origination facility)', and 'Located at cable head-end'. The first section includes Video/Audio sources, an Automation system (with TCP/IP socket), and a Human operator. The second section includes an Injector (with TCP/IP socket and MPEG-2 TS), a Network cloud, and a PAMS (with TCP/IP socket) connected to a Human operator. The third section includes a Digital compression system (DCS) with a Splicer, Primary and Insertion multiplexes, and an Output multiplex, connected to a Server via an SCTE 30 network connection. Arrows indicate the flow of data, including baseband video/audio, DPI trigger messages, AS to PAMS provisioning messages, and provisioning and alarms.
+
+**Figure 6-1 – ITU-T J.181 overall system block diagram with bidirectional data communications**
+
+J.287(14)\_F6-1
+
+![Figure 6-2 – ITU-T J.181 overall system block diagram with unidirectional data communications. The diagram is divided into three horizontal sections: 'Located at origination facility', 'Located at uplink', and 'Located at cable head-end'. At the origination facility, 'Video/Audio sources' are connected to an 'Automation system' via 'Automation control'. The 'Automation system' is connected to a 'Human operator'. 'DPI trigger messages carried in VANC' are sent from the 'Automation system' to the 'Injector' at the uplink. The 'Injector' receives 'Baseband video/audio' from the sources and outputs an 'MPEG-2 TS' via a 'Transmission path'. At the uplink, the 'Injector' is connected to 'PAMS' via 'Provisioning and alarms'. 'PAMS' is connected to a 'Human operator'. The 'Transmission path' leads to a 'Network interface or demodulator' at the cable head-end. This is connected to a 'Primary multiplex' and an 'Insertion multiplex'. The 'Primary multiplex' and 'Insertion multiplex' are connected to a 'Splicer' via 'Primary channel' and 'Insertion channel' respectively. The 'Splicer' is connected to an 'Output channel' which leads to an 'Output multiplex'. A 'Server' is connected to the 'Splicer' via an 'SCTE 30 network connection' and a 'TCP/IP socket'.](af7916c89a458fdab6c3f443217388ae_img.jpg)
+
+```
+
+graph TD
+    subgraph OriginationFacility [Located at origination facility]
+        VAS[Video/Audio sources]
+        AS[Automation system]
+        HO1[Human operator]
+        VAS -- "Automation control" --> AS
+        AS <--> HO1
+    end
+
+    subgraph Uplink [Located at uplink]
+        I[Injector]
+        PAMS[PAMS]
+        HO2[Human operator]
+        I -- "Provisioning and alarms" --> PAMS
+        PAMS <--> HO2
+    end
+
+    subgraph CableHeadEnd [Located at cable head-end]
+        NID[Network interface or demodulator]
+        PM[Primary multiplex]
+        IM[Insertion multiplex]
+        S[Splicer]
+        OC[Output channel]
+        OM[Output multiplex]
+        S[Server]
+        subgraph SplicerInternal [ ]
+            direction TB
+            PC[Primary channel]
+            IC[Insertion channel]
+            TC[ ]
+            TC[TCP/IP socket]
+        end
+        style SplicerInternal fill:none,stroke:none
+        NID -- "Transmission path" --> PM
+        NID -- "Transmission path" --> IM
+        PM -- "Primary channel" --> S
+        IM -- "Insertion channel" --> S
+        S -- "Output channel" --> OM
+        S <--> |"SCTE 30 network connection"| S
+    end
+
+    VAS -- "Baseband video/audio" --> I
+    AS -- "DPI trigger messages carried in VANC" --> I
+    I -- "MPEG-2 TS" --> NID
+  
+```
+
+Figure 6-2 – ITU-T J.181 overall system block diagram with unidirectional data communications. The diagram is divided into three horizontal sections: 'Located at origination facility', 'Located at uplink', and 'Located at cable head-end'. At the origination facility, 'Video/Audio sources' are connected to an 'Automation system' via 'Automation control'. The 'Automation system' is connected to a 'Human operator'. 'DPI trigger messages carried in VANC' are sent from the 'Automation system' to the 'Injector' at the uplink. The 'Injector' receives 'Baseband video/audio' from the sources and outputs an 'MPEG-2 TS' via a 'Transmission path'. At the uplink, the 'Injector' is connected to 'PAMS' via 'Provisioning and alarms'. 'PAMS' is connected to a 'Human operator'. The 'Transmission path' leads to a 'Network interface or demodulator' at the cable head-end. This is connected to a 'Primary multiplex' and an 'Insertion multiplex'. The 'Primary multiplex' and 'Insertion multiplex' are connected to a 'Splicer' via 'Primary channel' and 'Insertion channel' respectively. The 'Splicer' is connected to an 'Output channel' which leads to an 'Output multiplex'. A 'Server' is connected to the 'Splicer' via an 'SCTE 30 network connection' and a 'TCP/IP socket'.
+
+**Figure 6-2 – ITU-T J.181 overall system block diagram with unidirectional data communications**
+
+# 7 Data communications
+
+The data communications system for this Recommendation can be described according to the "Open Systems Interconnection (OSI) Basic Reference Model" specified in [b-ITU-T X.200]. According to this functional model, information and services may be delivered from device to device by arranging the information into logical groupings or messages, delivering them to lower functional layers for transmission and, after reception, reconstituting the information into the proper form for use by the recipient.
+
+## 7.1 Concerning data communications (informative)
+
+In what follows, the names of the layers are those adopted by ISO and ITU in [b-ITU-T X.200], Open Systems Interconnection (OSI) – Basic Reference Model [b-ANSI/SCTE 67].
+
+Some of these names are also commonly used in broadcasting technology to express different concepts. This particularly applies to the terms "network" and "link" and care must be taken to avoid confusion. This is especially important to readers of this Recommendation, since concise usage of terminology may confuse others who are less familiar with this Recommendation and the OSI reference model.
+
+Readers unfamiliar with the OSI reference model are referred to the many tutorial websites available which explain these concepts in detail. The layers of the reference model are: Layer 1: Physical; Layer 2: Link; Layer 3: Network; Layer 4: Transport; Layer 5: Session; Layer 6: Presentation; and Layer 7: Application.
+
+## **7.2 Data communications requirements for this API (normative)**
+
+This Recommendation defines the application, presentation and session layers of the OSI basic reference model and relies upon other well-defined Recommendations to provide the lower-level layers necessary to function.
+
+The data communication requirements for this Recommendation are based on those of [ITU-T J.281], which expects a high quality of service, bidirectional, connection-oriented, end-to-end reliable communications system using TCP. These expectations should be understood as the norm for this API. In this case, TCP over IP will provide the bottom four layers of the OSI basic reference model.
+
+In addition to the above normative data communications system requirements, automation system to injector messages defined in this Recommendation may also be carried over a low noise, high quality of service, bidirectional point-to-point communications systems consisting of encapsulation within serial digital (SDI) video signal(s) in one or both directions (or a return path of suitable bandwidth capable of carrying TCP segments as per [b-IETF RFC 793]). Within SDI/HD-SDI video, the segments shall be carried in VANC as per [SMPTE ST 2010].
+
+A subset of the automation system to injector messages defined in this Recommendation may also be carried over a low noise, high quality of service, unidirectional, point-to-point communications system using encapsulation within a video signal. The physical conveyance shall be in VANC as per [SMPTE ST 2010] for serial digital component systems. In this case, these communications methods will provide the bottom four layers of the OSI basic reference model. A full set of these messages may be carried in VANC for a serial digital component system; however, a subset of them will not actually be used (see clause 13.1).
+
+It is also possible to construct a high quality of service, connection-oriented, bidirectional communications system with one direction conveyed within the video signal and responses via a different path. Such a system will take careful engineering and may have some additional risks. Such a system may be able to gracefully degrade to a standard unidirectional, connection-oriented communications system upon loss of the return path.
+
+## **7.3 Conveyance quality of service considerations (informative)**
+
+The fundamental requirement for all modes of operation under this Recommendation is to provide a high quality of service to the API messages. For TCP/IP communications, this may seem obvious. For video conveyance, the requirements are less obvious.
+
+Serial digital component video must have a signal loss in a link of less than 30 dB (see [b-SMPTE ST 259]), which translates into a maximum bit-error rate of  $2 \times 10^{-7}$  or a signal to noise ratio of better than 17.1 dB. This is actually marginal performance since it translates into an error per frame of video (most viewers will judge it to be noisy). A realistic performance of a link should be an SNR of better than 20 dB (a BER of  $8 \times 10^{-14}$ ) which in viewer's terms is one error a day.
+
+In analogue video terms, this level of performance requires ANSI/EIA/TIA-250-C "short haul" link performance, with a minimum analogue signal-to-noise ratio of 57 dB.
+
+It is recognized that all "real world" communications systems may be subject to periodic degradation from external sources ("rain fade") that temporarily add considerable noise to the link. As a result, the conveyance requirements outlined in this document will endeavour to add an extra link margin to their message designs.
+
+## **7.4 Unidirectional system considerations (informative)**
+
+The requirements for unidirectional conveyance in the video signal are reasonably straightforward. The messages will be inserted via an insertion unit designed for inserting signals in video.
+
+This Recommendation assumes correct delivery of each message. It must be understood that in a unidirectional, video conveyed system, the automation system may choose to operate in a "best effort is OK" manner, and retransmit messages at least twice to ensure they have been completely received. Such a system architecture may be desirable where the digital compression system is located some distance away from the origination facilities (and hence the automation system) and a no return path can be provided.
+
+## **7.5 Proxy devices (normative)**
+
+A proxy device is a device which accepts messages as per this API (as either TCP/IP or bidirectional serial data communications) and places the appropriate messages of this API into the VANC area of the associated serial digital video supplied to the injector as [SMPTE ST 2010]. Such a device should engage in all of the automation system to injector initialization "handshaking" specified in clause 9.1 of this Recommendation. Such handshaking should not be passed to the injector in VANC.
+
+All other messages for the injector should be passed in VANC, including the Alive ("heartbeat") messages specified in clause 9.2.
+
+The proxy device should respond to all messages in lieu of actual responses from the injector, using (where appropriate) the proxy response code defined in Table 13-1.
+
+In a unidirectional carriage in VANC, the proxy device implementation may choose to support the deferred processing mode as outlined in clause 13.1.2.3 of this document. In such cases, upon arrival of the triggering event, the proxy device must remove the `timestamp()` structure as presented by the AS and replace it with a single byte of 0, as per clause 12.5.1, change the `messageSize` value to reflect that change, and move the remainder of the bytes in the message forward to fill in as appropriate.
+
+NOTE – The above requirements facilitate redundancy switching of proxy devices connected to the serial digital video signals to injectors. In the case of a proxy device failure, the new proxy device can re-initialize with the automation system, which is then aware of the failure, and able to resend any splice commands it deems necessary.
+
+# **8 Message formats**
+
+Messages in this API all possess a general message structure that wraps the data for the specific requests or responses being sent. This is done so that when the message is received, a common parsing routine can store it, determine what the structure of the data is, and ensure that the request and/or response and associated data is processed correctly. The end result of the operations carried by this API are the placement of ITU-T J.181 transport stream (TS) private sections in the outgoing TS and transmission to downstream splicing equipment. Within this document, these private sections will be referred to as "splice\_info\_sections," using the specific terminology of [ITU-T J.181].
+
+## **8.1 Terminology (informative)**
+
+The following terms will be used to indicate which level of the communications structure is being discussed. A `splice_info_section` will indicate information in the resultant TS, on one or more PIDs designated for this purpose, which communicate with downstream splicing devices. A "message" will indicate information communicated between the automation system and the compression system via
+
+this API. A given "operation" may be termed a "request" or a "response," and will indicate an individual specific action to be taken by either the compression system or the automation system. Such action may result in a `splice_info_section` being generated.
+
+There are four different categories of operations (requests and responses) provided by this API. These are "Basic," "Normal," Control, and "Supplemental". Basic operations supply the base communications required to support the system. Normal operations supply the base DPI-related functions (splicing, schedules, etc.). Supplemental operations are modifiers of "Normal" operations. Control operations manage the control word database required for encryption support. Detail is provided in clause 8.3.1.
+
+## 8.2 Message structures (normative)
+
+Messages in this API are defined on the assumption that they will be carried via TCP/IP and all delivered as part of a single datagram.
+
+Messages in this API carried via TIA/EIA-232-F (or TIA/EIA-422-B) shall utilize the basic link layer syntax specified in Annex B.
+
+Messages in this API carried in analogue video shall also utilize the basic link layer syntax specified in Annex B. The implementation details are left to the system manufacturer. A discussion of the link layer requirements is found in Annex D.
+
+Messages in this API carried via serial digital video do not require any additional "wrapping". See Annex C.
+
+Where field lengths in the resulting ITU-T J.181 `splice_info_section` are less than a byte, they are padded on the MSB side to fill an even byte count for ease of debugging. The high-order byte in multiple byte fields is transmitted first, the lower order byte last. The injector can pull the required number of bits from the message in forming the resulting actual `splice_info_section` TS packet. Each message begins with an operation identifier field, followed by a length field.
+
+### 8.2.1 Addressing of particular items within a system
+
+Two variables are provided in each of the messages to ensure the ability to uniquely identify the origination and the destination of messages. For a request for section insertion into an output TS, **AS\_index** identifies the automation system generating the request and the specific programme component (**DPI\_PID\_index**) for which the resulting ITU-T J.181 `splice_info_section` is intended. For responses, this indicates the specific automation system (**AS\_index**) for which the response is intended.
+
+The presence of these variables within this API is not intended to require support of the generation of multiple DPI PIDs by a single injector, since the support of multiple DPI PIDs is optional (see clause 11.4).
+
+#### 8.2.1.1 AS\_index
+
+**AS\_index** uniquely identifies the source of the message (since it is possible to have several automation systems active at once). The number ranges from 0 to 255 and shall be zero if this index is not required. This variable takes the value returned by the "**AS\_index**" field of the `config_response` message (see clause 9.3.2). A redundant AS shall be assigned one single value of **AS\_index** which applies to both the primary and backup. Either the primary or the backup is active at a given time, but not both. An injector instance shall be connected to only one AS at a given time. If non-zero, **AS\_index** shall be unique within a single DCS.
+
+In systems where the PAMS to AS communications are not utilized, it is the operational responsibility of the digital compression system operator and the automation system operator to each assign values so that they are unique for each automation system communicating with a given injector instance through this API and that only one automation system at a time will communicate with a given
+
+injector instance (a single value of **DPI\_PID\_index** for that injector). The injector will ensure that messages received via the automation interface will only be used if authorized.
+
+#### 8.2.1.2 **DPI\_PID\_index**
+
+**DPI\_PID\_index** specifies the index to the DPI PID which will carry the resulting splice\_info\_sections. The number ranges from 0 to 65535. **DPI\_PID\_index** shall be zero if not required by the system architecture.
+
+The **DPI\_PID\_index** allows a given automation system to direct messages to a specific DPI PID within a specific MPEG program in a specific transport stream (TS) within the purview of the operational system (DCS). This is especially important when there are multiple DPI PIDs referenced by the PMT of a single MPEG program.
+
+**DPI\_PID\_index** is required only if multiple injector instances (logical injectors) are present for any physical connection or if one or more injector instances are generating more than one DPI PID. Examples of situations requiring non-zero values of **DPI\_PID\_index** are multiple injectors listening to the same physical connection, such as multiple injectors receiving the same video stream, or multiple injector instances located behind a single IP address and port number.
+
+Ordinarily, there shall be one value of **DPI\_PID\_index** for each DPI PID referenced by a program's PMT for each program within the purview of the DCS. The exception to the rule is the case where a single DPI PID is shared by more than one program within a single TS. In this case, more than one PMT may make reference to the same shared DPI PID via a common value for **DPI\_PID\_index**.
+
+Multiple language versions of the same movie are an example where this facility may be utilized. The AS is expected to know what these programs are and that the same value of **DPI\_PID\_index** may be assigned for each. In this example, the different programs share a video PID but have different audio PIDs for each language. The associated DPI PID for the video could be the same or different in this case.
+
+The AS may validate for shared PIDs before sending a provisioning\_response message (see clause 10.5.1.2).
+
+In all other circumstances, each value of **DPI\_PID\_index** shall be unique.
+
+This value is normally furnished to the AS by the PAMS during system initialization as part of the injector service notification (via the provisioning\_request message; see clause 9.4). In systems without PAMS to AS service, this value must be manually provided to the automation system.
+
+It is recommended that even trivial system architectures utilize non-zero values of **DPI\_PID\_index**.
+
+### 8.2.2 **Single operation message**
+
+This variable length structure carries a single instance of an operation (request or response as it will be normally termed) listed in Table 8-3 and whose structural details are provided in clauses 9 and 9.8.9.
+
+Operations listed in Table 8-3 shall use the single\_operation\_message() and shall not use multiple\_operation\_message().
+
+**Table 8-1 – Single operation message**
+
+| Syntax                       | Bytes | Type   |
+|------------------------------|-------|--------|
+| single_operation_message() { |       |        |
+| opID                         | 2     | uimsbf |
+| messageSize                  | 2     | uimsbf |
+| result                       | 2     | uimsbf |
+| result_extension             | 2     | uimsbf |
+| protocol_version             | 1     | uimsbf |
+| AS_index                     | 1     | uimsbf |
+| message_number               | 1     | uimsbf |
+| DPI_PID_index                | 2     | uimsbf |
+| data()                       | *     | Varies |
+| }                            |       |        |
+
+#### **8.2.2.1 Semantics of fields in single\_operation\_message()**
+
+**opID:** An integer value that indicates which message is being sent. See Table 8-3. It shall only take values whose "Usage" column entries are listed as "Basic Request" or "Basic Response".
+
+**messageSize:** The size of the entire single\_operation\_message() structure in bytes.
+
+**result:** The results to the requested message. See clause 14 for details on the result codes. For message usage types (as shown in the "Usage" column of Table 8-3) other than "Basic Response" messages, this shall be set to 0xFFFF.
+
+**result\_extension:** This shall be set to 0xFFFF unless used to send additional result information in a response message.
+
+**protocol\_version:** An 8-bit unsigned integer field whose function is to allow, in the future, this message type to carry parameters that may be structured differently to those defined in the current protocol. It shall be zero (0x00). Non-zero values of **protocol\_version** may be used by a future version of this Recommendation to indicate structurally different messages.
+
+**AS\_index:** This is defined in clause 8.2.1. Response messages return the value from the corresponding Request message.
+
+**message\_number:** The **message\_number** can be any number in the range 0 to 255. The **message\_number** must be unique for the life of a message within a given injector instance. The **message\_number** is used to identify an individual request.
+
+When multiple copies of the same message are sent, they can be identified because they have the same **message\_number**. If not in current use, the **message\_number** may freely vary over the range of 0 to 255.
+
+In a unidirectional system, the message number can be assumed to be available for reuse after the last copy of the message is sent and after the associated processing timestamp() time has passed.
+
+**DPI\_PID\_index:** This is defined in clause 8.2.1. Response messages return the value from the corresponding request message.
+
+**data():** Specific data structure for the message being sent. Details on each of the messages containing data are described below. The size of this field is equal to the **MessageSize** minus the size of the fixed portion of single\_operation\_message() and is determined by the size of the data being added to the message. Not all messages utilize the data() field.
+
+### 8.2.3 Multiple operation message
+
+This variable length structure carries one or more of the operations (or requests) listed in Table 8-4, which must be either "Normal", "Control" or "Supplemental" in the usage category and whose structural details are provided in clause 9 of this Recommendation. Each request in the data() structure includes an **opID** value (2 bytes) and a length (2 bytes). Thus the first 4 bytes of every request within the repeating structure is identical to easily permit a receive device to skip a request if the **opID** is unknown. This allows for extensions to the protocol in the future.
+
+Use of the multiple\_operation\_message() will normally result in the insertion of at least one ITU-T J.181 splice\_info\_section into the resultant TS, unless the injector (IJ) detects fatal errors in the message. In multiple byte fields the first byte received is the most significant byte. The value placed in the ITU-T J.181 splice\_info\_section variable named "**tier**" may be user specified by the insert\_tier\_data() request (see clause 9.8.9). In the absence of an insert\_tier\_data() request, the injector shall set "**tier**" to the default value 0xFFF.
+
+Note that the use of the multiple\_operation\_message() will result in a single\_operation message in response, since response messages are defined as "Basic Usage" responses (which, by definition, use the single\_operation\_message).
+
+#### 8.2.3.1 Order of request execution
+
+This structure permits multiple requests to be grouped together to permit transmission in one message (and execution as appropriate). Its use is permitted in both bidirectional (serial or TCP/IP-based) and unidirectional systems. The data() structure is populated with one or more of the request structures defined in clause 9 (within the constraints identified elsewhere in this document). The time of processing may be instantaneous or delayed, as required.
+
+All requests are executed in the order that they exist within the data() structure. If requests are time based, then the time is referenced to the start of the video frame that the last byte is received, not the frame in which it was actually processed.
+
+Requests listed in Table 8-3 shall not use the multiple\_operation\_message().
+
+Some requests are order dependant, such as the various supplemental requests. The supplemental request modifies the characteristics of a normal request, so they must be carried following the associated normal request. In this way, multiple normal requests with supplemental requests can be carried without confusing which supplemental request is associated with which normal request.
+
+Each instance of data() shall begin with a normal or a control request. A normal request may be followed by zero or more supplemental requests which modify or augment it. Unless otherwise specified, supplemental request operations may occur in any order, except that they must follow the normal operation to which they apply. It may then be followed by additional normal requests for which the AS requests time deferral. The placement of a new normal request shall indicate that the definition of the preceding normal request is complete and that the resulting ITU-T J.181 splice\_info\_section can be formatted and output at the time indicated by timestamp().
+
+As used here, the term "processed" refers to whatever operations the injector must accomplish to emit an ITU-T J.181 section or sections or change a CW database. Processing begins when the timestamp() time has expired and ends when the section or sections are placed in the TS or the database is updated.
+
+#### 8.2.3.2 Format of the multiple\_operation\_message() structure
+
+**Table 8-2 – Multiple operation message**
+
+| Syntax                         | Bytes | Type   |
+|--------------------------------|-------|--------|
+| multiple_operation_message() { |       |        |
+| Reserved                       | 2     | uimsbf |
+| messageSize                    | 2     | uimsbf |
+| protocol_version               | 1     | uimsbf |
+| AS_index                       | 1     | uimsbf |
+| message_number                 | 1     | uimsbf |
+| DPI_PID_index                  | 2     | uimsbf |
+| SCTE35_protocol_version        | 1     | uimsbf |
+| timestamp()                    | *     | Varies |
+| num_ops                        | 1     | uimsbf |
+| for (i=0; i < num_ops; i++ ) { |       |        |
+| opID                           | 2     |        |
+| data_length                    | 2     |        |
+| data()                         | *     | Varies |
+| }                              |       |        |
+| }                              |       |        |
+
+#### 8.2.3.3 Semantics of fields in multiple\_operation\_message()
+
+**Reserved:** This field shall be set to all ones (0xFFFF).
+
+**messageSize:** The size of the entire multiple\_operation\_message() structure in bytes.
+
+**protocol\_version:** An 8-bit unsigned integer field whose function is to allow, in the future, this message type to carry parameters that may be structured differently to those defined in the current protocol. It shall be zero (0x00). Non-zero values of **protocol\_version** may be used by a future version of this Recommendation to indicate structurally different messages.
+
+**AS\_index:** This is defined in clause 8.2.1.
+
+**message\_number:** An integer value that is used to identify an individual message. The **message\_number** variable must be unique for the life of a message. When multiple copies of the same message are sent, they can be identified because they have the same **message\_number**. This means that for messages that are to be processed in the future, the **message\_number** may not be reused until the message has been processed. If not in current use, the **message\_number** may freely vary over the range of 0 to 255.
+
+In a unidirectional system, the message number can be assumed to be available for reuse after the associated processing timestamp() time has passed.
+
+**DPI\_PID\_index:** This is defined in clause 8.2.1.
+
+**SCTE35\_protocol\_version:** This 8-bit unsigned integer field indicates the version of SCTE 35 protocol that the section which results from this message conforms to. Its function is to allow, in the future, this section type to carry parameters that may be structured differently to those defined in the current protocol. At present, the only valid value defined by [ITU-T J.181] is zero (0x00). Non-zero values of **SCTE35\_protocol\_version** may be used by a future version of this Recommendation to indicate structurally different sections.
+
+**timestamp()**: This field delivers the exact time to process all of the requests in this message (see clause 12.5). The **time\_type** field of **timestamp()** may be zero, indicating the messages are processed immediately. The **timestamp()** may contain either the UTC time or the VITC time specifying when to process the requests. The **timestamp()** may alternatively contain the number of the GPI to use for triggering the messages to be processed. Once the GPI is triggered, all requests associated with that edge of the GPI will be processed.
+
+**num\_ops**: An integer value that indicates the number of requests contained within the **data()** loop.
+
+**opID**: An integer value that indicates which request is being sent. See Table 8-4.
+
+**data\_length**: The size of the **data()** field being sent in bytes.
+
+**data()**: Specific data structure for the request being sent. Details on each of the requests containing data are described in clauses 9.3.1, 9.4, 9.5, 9.7 and 9.8. The size of this field is equal to **data\_length** and is determined by the size of the data being added to the **multiple\_operation\_message()** structure.
+
+#### 8.2.3.4 Detailed discussion of message syntax and semantics
+
+Note that each **opID** in Table 8-4 has an associated "Usage" column, which indicates the class of each request. Normal requests have no associations with other requests and (once the time value specified in the **timestamp()** structure is reached) are immediately formatted into the appropriate ITU-T J.181 message and dispatched. Each normal request may be followed by zero or more "Supplemental" requests. The supplemental requests must follow immediately after the normal request that they are modifying. Some supplemental requests are specific to a certain type of normal request. Others are a general supplemental request that can be associated with any normal request, when appropriate. The injector must ensure in processing any normal requests that it checks for the existence of associated supplemental requests before inserting the transport packet into the multiplex.
+
+For the control requests, only one request per control word index is permitted within a single **multiple\_operation\_message()**. It is permitted to send several requests in the same message, each operating on different control words. For example, update CW\_index 1 and delete CW\_index 2 in the same message is permitted. It would not be permitted to update CW\_index 1 and then delete CW\_index 1 within the same message.
+
+DPI schedules are potentially very large. The system is downloading a playlist of future ad avail periods, one splice point at a time. There is a single start message, and a single stop message, to frame the downloading of the data. Like other messages in this API, the schedules have normal and supplemental features. If supplemental features are required, they must be included in the same message as the basic schedule request, and immediately following the associated basic request.
+
+If multiple normal requests are present in a message, then the requests are processed in the same order that they appear in the message. If the **time\_type** field of **timestamp()** is zero, all normal request timing is relative to the arrival time of the last byte of the message. Please see clause 8.2.3.1 for additional information.
+
+## 8.3 Operation types (normative)
+
+Tables 8-3 and 8-4 contain the assigned values for each type of operation (request or response) supported by this API. Other columns in the tables list information identifying the normal originator and recipient, and other useful information.
+
+Those operations required for the simple profile appear in the column labelled "In Simple Profile", with an indication of "Y". An "N" indicates that support of the request is not required for compliance. "n/a" indicates "not applicable". With the sole exception of the "general\_response\_data()" message, compliant implementations may also omit support for those messages in Table 8-3 which show PAMS as either the "Sent By" or "Sent To" when the PAMS is not a constituent portion of the overall
+
+system. Systems with PAMS as the constituent portion of the overall system should indicate this as "Simple Profile with PAMS," or, if applicable (and as an example), "Simple Profile plus encryption with PAMS".
+
+**Table 8-3 – opID assigned values and meanings for single\_operation\_messages**
+
+| <b>opID assigned value</b> | <b>Operation name</b>           | <b>Sent by</b>               | <b>Sent to</b>               | <b>In simple profile</b> | <b>Description</b>                                                                                                                | <b>Usage</b>   |
+|----------------------------|---------------------------------|------------------------------|------------------------------|--------------------------|-----------------------------------------------------------------------------------------------------------------------------------|----------------|
+| 0x0000                     | general_response_data()         | PAMS, automation or injector | PAMS, automation or injector | Y                        | Used to convey asynchronous information between the devices. There is no data() associated with this message.                     | basic response |
+| 0x0001                     | init_request_data()             | Automation                   | Injector                     | Y                        | Initial message to the injector on predefined port                                                                                | basic request  |
+| 0x0002                     | init_response_data()            | Injector                     | Automation                   | Y                        | Initial response to automation on the established connection                                                                      | basic response |
+| 0x0003                     | alive_request_data()            | Automation                   | Injector                     | Y                        | Sends an alive message to acquire current status.                                                                                 | basic request  |
+| 0x0004                     | alive_response_data()           | Injector                     | Automation                   | Y                        | Response to the alive message indicating current status.                                                                          | basic response |
+| 0x0005 – 0x0006            | User defined                    |                              |                              | n/a                      | Receiving devices shall ignore these values. Used in legacy systems.                                                              |                |
+| 0x0007                     | inject_response_data()          | Injector                     | Automation                   | Y                        | Response to indicate that the request was received and that the injector is preparing to send an ITU-T J.181 message or messages. | basic response |
+| 0x0008                     | inject_complete_response_data() | Injector                     | Automation                   | Y                        | Response from the injector when all resultant ITU-T J.181 splice messages are sent.                                               | basic response |
+| 0x0009                     | config_request_data()           | Automation                   | PAMS                         | n/a                      | Automation sends PAMS its IP configuration                                                                                        | basic request  |
+| 0x000A                     | config_response_data()          | PAMS                         | Automation                   | n/a                      | Responds to Config_Request                                                                                                        | basic response |
+| 0x000B                     | provisioning_request_data()     | PAMS                         | Automation                   | n/a                      | PAMS notification of the injectors provisioned for DPI service                                                                    | basic request  |
+
+**Table 8-3 – opID assigned values and meanings for single\_operation\_messages**
+
+| <b>opID assigned value</b> | <b>Operation name</b>                           | <b>Sent by</b>     | <b>Sent to</b>   | <b>In simple profile</b> | <b>Description</b>                                                        | <b>Usage</b>   |
+|----------------------------|-------------------------------------------------|--------------------|------------------|--------------------------|---------------------------------------------------------------------------|----------------|
+| 0x000C                     | provisioning_response_data()                    | Automation         | PAMS             | n/a                      | Response from automation that the message is received and DPI is starting | basic response |
+| 0x000D – 0x000E            | Reserved                                        |                    |                  | n/a                      | Range reserved<br>Used in legacy systems.                                 |                |
+| 0x000F                     | fault_request_data()                            | Automation         | PAMS             | n/a                      | Automation discovered communication problem with an injector              | basic request  |
+| 0x0010                     | fault_response_data()                           | PAMS               | Automation       | n/a                      | Response from PAMS                                                        | basic response |
+| 0x0011                     | AS_alive_request_data()                         | PAMS               | Automation       | n/a                      | Maintain PAMS to AS communications                                        | basic response |
+| 0x0012                     | AS_alive_response_data()                        | Automation         | PAMS             | n/a                      | Maintain AS to PAMS communications                                        | basic response |
+| 0x0013 – 0x00FF            | Reserved for future basic requests or responses |                    |                  | n/a                      | Range reserved for future standardization.                                |                |
+| 0x0100 – 0x7FFF            | Reserved                                        |                    |                  | n/a                      | Range reserved for Table 8-4 uses                                         |                |
+| 0x8000 – 0xBFFF            | User defined                                    | Automation or PAMS | Injector or PAMS | n/a                      | Range available for user-defined functions.                               |                |
+| 0xC000 – 0xFFFE            | Reserved                                        |                    |                  |                          | Range reserved for user-defined Table 8-4 uses.                           |                |
+| 0xFFFF                     | Reserved                                        |                    |                  |                          | Reserved value                                                            |                |
+
+**Table 8-4 – opID assigned values and meanings for multiple\_operation\_messages**
+
+| opID assigned value | Operation name                                | Sent by    | Sent to  | In simple profile | Description                                                       | Usage        |
+|---------------------|-----------------------------------------------|------------|----------|-------------------|-------------------------------------------------------------------|--------------|
+| 0x0000 –0x00FF      | Reserved                                      |            |          | n/a               | Range reserved (see Table 8-3).                                   |              |
+| 0x0100              | inject_section_data_request()                 | Automation | Injector | Y                 | Generates an ITU-T J.181 section directly                         | Normal       |
+| 0x0101              | splice_request_data()                         | Automation | Injector | Y                 | Normally used request to send an ITU-T J.181 message or messages. | Normal       |
+| 0x0102              | splice_null_request_data()                    | Automation | Injector | Y                 | Generates an ITU-T J.181 splice_null operation                    | Normal       |
+| 0x0103              | start_schedule_download_request_data()        | Automation | Injector | N                 | Initiates schedule download                                       | Normal       |
+| 0x0104              | time_signal_request_data()                    | Automation | Injector | Y                 | Generates an ITU-T J.181 time_signal operation                    | Normal       |
+| 0x0105              | transmit_schedule_request_data()              | Automation | Injector | N                 | Initiates schedule transmission                                   | Normal       |
+| 0x0106              | component_mode_DPI_request_data()             | Automation | Injector | N                 | Adds component mode to a DPI request                              | Supplemental |
+| 0x0107              | encrypted_DPI_request_data()                  | Automation | Injector | N                 | Adds encryption to a DPI request                                  | Supplemental |
+| 0x0108              | insert_descriptor_request_data()              | Automation | Injector | Y                 | Adds a descriptor to another operation                            | Supplemental |
+| 0x0109              | insert_DTMF_descriptor_request_data()         | Automation | Injector | Y                 | Adds a DTMF descriptor to another operation                       | Supplemental |
+| 0x010A              | insert_avail_descriptor_request_data()        | Automation | Injector | Y                 | Adds an avail_descriptor to the ITU-T J.181 section               | Supplemental |
+| 0x010B              | insert_segmentation_descriptor_request_data() | Automation | Injector | Y                 | Adds a segmentation descriptor to another operation               | Supplemental |
+| 0x010C              | proprietary_command_request_data()            | Automation | Injector | Y                 | Adds a proprietary descriptor to another operation                | Normal       |
+| 0x010D              | schedule_component_mode_request_data()        | Automation | Injector | N                 | Adds component mode to an avail definition                        | Supplemental |
+
+**Table 8-4 – opID assigned values and meanings for multiple\_operation\_messages**
+
+| <b>opID assigned value</b> | <b>Operation name</b>              | <b>Sent by</b>     | <b>Sent to</b>   | <b>In simple profile</b> | <b>Description</b>                                                                            | <b>Usage</b> |
+|----------------------------|------------------------------------|--------------------|------------------|--------------------------|-----------------------------------------------------------------------------------------------|--------------|
+| 0x010E                     | schedule_definition_data() request | Automation         | Injector         | N                        | Single avail definition                                                                       | Supplemental |
+| 0x010F                     | insert_tier_data()                 | Automation         | Injector         | Y                        | Specifies tier data                                                                           | Supplemental |
+| 0x0110 -0x02FF             | Reserved                           |                    |                  | n/a                      | Range reserved for future standardization (additional "Normal" or "Supplemental" operations). |              |
+| 0x0300                     | delete_ControlWord_data() request  | Automation         | Injector         | N                        | Maintains CW database                                                                         | Control      |
+| 0x0301                     | update_ControlWord_data() request  | Automation         | Injector         | N                        | Maintains CW database                                                                         | Control      |
+| 0x0302 – 0x7FFF            | Reserved                           |                    |                  | n/a                      | Range reserved for future standardization (additional "Control" operations).                  |              |
+| 0x8000 – 0xBFFF            | Reserved                           |                    |                  | n/a                      | Range reserved (see Table 8-3).                                                               |              |
+| 0xC000 – 0xFFFE            | User defined                       | Automation or PAMS | Injector or PAMS | n/a                      | Range available for user-defined functions for multiple operation messages.                   |              |
+| 0xFFFF                     | Reserved                           |                    |                  |                          | Reserved value.                                                                               |              |
+
+### 8.3.1 Meaning of the Usage field in Tables 8-3 and 8-4
+
+The Usage field indicates the class of each request or response and the messages with which they may be used:
+
+- Basic requests or responses shall always use the `single_operation_message()` structure (see clause 8.2.2).
+- Normal requests shall have no linkage with other normal requests and are normally formatted into the appropriate ITU-T J.181 `splice_info_section` and dispatched. Normal requests shall use the `multiple_operation_message()` structure (see clause 8.2.3.2). While multiple normal requests may be grouped together into a single instance of `multiple_operation_message()`, they may not have any dependencies beyond the execution order (see clause 8.2.3.1).
+- Supplemental requests are also carried only by the `multiple_operation_message()` structure (see clause 8.2.3). Each supplemental request follows immediately after the normal request that they are modifying. Some supplemental requests are specific to a certain request. Others are a general request that can be associated with any normal request, when appropriate.
+- Control requests are also carried only by the `multiple_operation_message()` structure (see clause 8.2.3). Each control request shall be independent of any other contained within the same `data()` structure and shall be executed at the time specified in the `timestamp()`. Multiple control requests may be present within the `data()` structure. Supplemental requests do not modify control requests.
+
+## 8.4 Conventions and requirements
+
+1. Each message that contains data is outlined with its data fields and types below. Additional structures are indicated as functions and are described in clause 12.
+2. The injector shall retain the following data values while messages are being processed:
+  - `message_number`
+  - `splice_event_id`
+
+These are retained until the `inject_complete_response` message is sent to the AS. In addition, each injector which supports splice schedule messages must retain any descriptors defined via this API during the output of the individual ITU-T J.181 `splice_schedule()` sections which result from a single `schedule_definition` request (see clause 9.7).
+
+3. All string lengths have space reserved for a null terminator character (0x00) and shall use null terminated strings. The size defined for the string is constant and will not vary depending on the actual length of the string. As an example, a string that is defined as 16 characters can have at most 15 characters of data followed by a null character. Once a null is encountered in scanning a string, the rest of the characters in the string are undefined and ignored. This Recommendation uses 8 bit ASCII characters for strings.
+4. Response messages shall be sent out without unnecessary delay. The device expecting a response should consider no response within 5 seconds to indicate a timeout. When the automation system suspects a timeout, it shall send an `alive_request` message. If the injector does not answer as specified in this document, the connection for this channel shall be dropped and re-established.
+5. Initialization (or re-initialization) of the communications between the AS and the injector shall not cause interruption of any of the audio, video or DPI message insertions currently being processed by either the AS or the injector. Initialization can be safely conducted at any point in time. This includes changes to injector services or injectors themselves. These events may be expected to occur at random intervals.
+
+6. When a device is polling to start or restart communications, a suitable interval (30 to 60 seconds) may be left between attempts. Such an interval might be randomly determined, with exponential backoff, as is commonly used in Ethernet-based protocols.
+
+# 9 Automation system to injector communication
+
+## 9.1 Initialization
+
+The methods of initializing the TCP/IP communications parameters are discussed in clause 10.4.
+
+For TCP/IP, the initial communication begins with the injector listening on predefined port 5167 and the automation system opening an API connection to the injector via that socket. If another socket number has been furnished in the provisioning\_request message (via the injector\_socket\_number field), that socket should be used instead of the default socket 5167. The automation system sends an **init\_request** message to the injector. The automation system then listens for the response from the injector on the established API connection. All further communication is done on this API connection. Either the automation system or injector may terminate communications by closing this API connection. Each device is responsible for detecting and properly handling a closed API connection.
+
+The injector should support multiple automation system connections simultaneously, if provisioned to do so. When the injector initializes the TCP listener on port 5167 it should allow for the number of API connections it is provisioned for (see clause 11.4). No two automation systems may have an active connection to any given injector instance at any one time. The injector instance shall return a response of "Injector is already in use" (see Table 14-1) if this occurs.
+
+The **protocol\_version** fields in single\_operation\_message() and multiple\_operation\_message() permit the automation system and the digital compression system to "negotiate" at which level of the protocol the system will function. The lesser value shall be taken as the operating point for the system as initialized. Please note that this value may have implications upon the possible values for the **SCTE35\_protocol\_version** field (see clauses 8.2.2 and 8.2.3).
+
+In a unidirectional system, the AS and injector must both be configured to operate at a compatible protocol version.
+
+### 9.1.1 init\_request AS ==> IJ
+
+This basic usage request is sent by the automation system to the injector to initialize a TCP/IP connection. The appropriate value for the desired **protocol\_version** shall be furnished to the injector in this message.
+
+Table 9-1 – init\_request\_data
+
+| Syntax                    | Bytes | Type |
+|---------------------------|-------|------|
+| init_request_data(){<br>} |       |      |
+
+### 9.1.2 init\_response IJ ==> AS
+
+This basic usage response is sent by the injector to the automation system to indicate the receipt of the init\_request. The appropriate value for desired **protocol\_version** shall be furnished to the AS in this message. All devices supporting this API shall operate from this point forward at the lesser of the furnished **protocol\_version** values.
+
+**Table 9-2 – init\_response\_data**
+
+| Syntax                     | Bytes | Type |
+|----------------------------|-------|------|
+| init_response_data(){<br>} |       |      |
+
+A proxy device may respond to this message with a "Proxy Response" **result** code (see Table 14-1). This permits the automation system, should it desire to do so, to track whether or not a given injector is served by a proxy device or a direct connection.
+
+## 9.2 Alive ("Heartbeat") communications
+
+For bidirectional communications, once initialization is complete, then the automation system shall send **alive\_request** messages to ensure that the injector and the communications path remain up and running. Each **alive\_response** message (wrapped in the single\_operation\_message()) contains a **result** field that may be used to signal if DPI support has been stopped on the recipient's end. If there has been no activity on the connection in the preceding 60 seconds, then an **alive\_request** message shall be sent.
+
+If TCP/IP is being used and the user de-provisions DPI support in the injector, the injector will close the socket connection to the automation system without waiting for the next **alive\_request**.
+
+For unidirectional communications this message also serves to provide a mechanism that the receiving device shall use to verify a working connection to the automation computer. This message shall be sent at least once every 60 seconds. If the messages fail to arrive, then the receiving injector shall notify its PAMS or a human operator that communications may be lost.
+
+The second function is to provide clock synchronization for UTC or VITC time-stamped splice messages. The time () structure provides the time for the start of the associated video frame. This requires the sender and the receiver to both be examining synchronous video of the same frame rate. In multi-standard systems, this requirement is very important.
+
+The receiving device can synchronize to the vertical interval of its incoming video and the received time () value and thus maintain a local UTC or VITC time base to use with time-stamped messages.
+
+For TCP/IP-based systems, implementers may choose to use an external time standard to keep the internal clocks of the automation system and the injector in sync. This is not strictly necessary for the simplest implementation that meets the requirements of [ITU-T J.181].
+
+If the automation system has access to a facility master clock, and it makes sense to both parties, then the current value of facility time-of-day time code can be transmitted in the "**alive\_request**" messages from the automation system to the injector and conversely in the injector to the automation system "**alive\_response**" responses. Alternatively, facility time-of-day time samples may be conveyed to the injector in the video signal proper as VITC.
+
+### 9.2.1 alive\_request AS ==> IJ
+
+This basic request serves to ensure that the AS to injector communications path remains open and reliable. In addition it may be used to ensure the internal time within each is synchronized. If deferred requests are to be used with a time-value trigger, then it is vital that synchronization be maintained.
+
+**Table 9-3 – alive\_request\_data**
+
+| Syntax                               | Bytes | Type |
+|--------------------------------------|-------|------|
+| alive_request_data(){<br>time()<br>} |       |      |
+
+#### **9.2.1.1 Semantics of fields in alive\_request\_data()**
+
+**time():** This is an optional structure, unless the **time\_type** field of the timestamp() structure carried in multiple operation messages is non-zero. The current UTC time clock of the sending device is checked as close as possible to the sending of the message. This is designed to be used by the injector and the automation system to check on how well the two systems are time synchronized. See clause 12.4 for a definition of **time()**. If this time synchronization is not being used in a given system, the value of time() may be set to zero.
+
+### **9.2.2 alive\_response IJ ==> AS**
+
+This basic response serves to ensure that the AS to injector communications path remains open and reliable. In addition, it may be used to ensure the internal time within which each is synchronized. If deferred requests are to be used with a time-value trigger, then it is vital that synchronization be maintained.
+
+**Table 9-4 – alive\_response\_data**
+
+| Syntax                                | Bytes | Type |
+|---------------------------------------|-------|------|
+| alive_response_data(){<br>time()<br>} |       |      |
+
+A proxy device should respond to this message with a "Successful Response" **result** code (see Table 14-1) as if it were an injector.
+
+#### **9.2.2.1 Semantics of fields in alive\_response\_data()**
+
+**time():** This is an optional structure, unless the **time\_type** field of the timestamp() structure carried in multiple operation messages is non-zero. The current UTC time clock of the sending device is checked as close as possible to the sending of the message. This is designed to be used by the injector and the automation system to check on how well the two systems are time synchronized. See clause 12.4 for a definition of **time()**. If this time synchronization is not being used in a given system, the value of time() may be set to zero.
+
+## **9.3 Splice requests**
+
+After initializing communications with the injector, the automation system can issue (via a multiple operation message), one of the normal requests listed in the Usage column of Table 8-4. Typically a splice\_request is issued to initiate the placement of one or more ITU-T J.181 splice\_info\_sections into the outgoing TS. The automation system may choose to send any of the messages multiple times before the designated in-point (especially if return path communications is unavailable). The injector can detect that these are duplicates of one another by comparison of the **message\_number** fields.
+
+The two messages that are returned (in a bidirectional system) from the splice request messages are the inject\_response message and the inject\_complete\_response message. An inject\_response message is returned upon receipt of the splice request. An inject\_complete\_response message is returned once the ITU-T J.181 section has been generated.
+
+### 9.3.1 splice request AS ==> IJ
+
+This normal request is the usual carrier of splicing requests. It may be further elaborated upon by various supplemental type requests which may follow it within the data() structure of a multiple\_operation\_message.
+
+**Table 9-5 – splice\_request\_data**
+
+| Syntax                  | Bytes | Type   |
+|-------------------------|-------|--------|
+| splice_request_data() { |       |        |
+| splice_insert_type      | 1     | uimsbf |
+| splice_event_id         | 4     | uimsbf |
+| unique_program_id       | 2     | uimsbf |
+| pre_roll_time           | 2     | uimsbf |
+| break_duration          | 2     | uimsbf |
+| avail_num               | 1     | uimsbf |
+| avails_expected         | 1     | uimsbf |
+| auto_return_flag        | 1     | uimsbf |
+| }                       |       |        |
+
+#### 9.3.1.1 Semantics of fields in splice\_request\_data()
+
+**splice\_insert\_type**: An 8-bit unsigned integer defining the type of insertion operation desired. These will result in the generation of one or more ITU-T J.181 splice\_info() sections with a **splice\_command\_type** field value of splice\_insert with other inferred field values also being set within the resulting splice\_info() section. The other inferred field values are noted with the discussion of each assigned value. Please refer to clause 9.3.2 below for additional clarification of the inferred values.
+
+**Table 9-6 – splice\_insert\_type assigned values**
+
+| splice_insert_type    | Value assigned |
+|-----------------------|----------------|
+| reserved              | 0              |
+| spliceStart_normal    | 1              |
+| spliceStart_immediate | 2              |
+| spliceEnd_normal      | 3              |
+| spliceEnd_immediate   | 4              |
+| splice_cancel         | 5              |
+
+*spliceStart\_normal* section(s) occur at least once before a splice point. This interval should match the requirements of [ITU-T J.181] (clause 9.1) and serve to set up the actual insertion. It is recommended that if sufficient pre-roll time is given by the AS, the injector sends several succeeding ITU-T J.181 splice\_info\_section() sections (as per [ITU-T J.181] and [b-ANSI/SCTE 67]) in response to a single splice\_request message with a *spliceStart\_normal* **splice\_insert\_type** value. The minimum non-zero **pre\_roll\_time** is defined in clause 12.3.
+
+*spliceStart\_immediate* sections may come once at the splice point's exact location. The injector shall set the **splice\_immediate\_flag** to 1 and the **out\_of\_network\_indicator** to 1 in the resulting ITU-T J.181 splice\_info\_section() section. Usage of "immediate mode" signalling is not recommended by [ITU-T J.181] and may result in inaccurate splices.
+
+*spliceEnd\_normal* sections come to terminate a splice done without a duration specified. They may also be sent to ensure a splice has terminated on schedule. The injector sets the **out\_of\_network\_indicator** to 0. If they are to terminate a *spliceStart\_normal* with no duration specified, they should be sent prior to the minimum interval before the return point and carry a value for **pre\_roll\_time**, especially if terminating a long form insertion. The minimum non-zero **pre\_roll\_time** is defined in clause 12.3.
+
+*spliceEnd\_immediate* sections come to terminate a current splice before the splice point, or a splice in process earlier than expected. The injector sets the **out\_of\_network\_indicator** to 0 and the **splice\_immediate\_flag** to 1. The value of **pre\_roll\_time** is ignored.
+
+*splice\_cancel* sections come to cancel a recently sent *spliceStart\_normal* section. The AS must supply the correct value of **splice\_event\_id** for the section to be cancelled. The injector shall set the **splice\_event\_cancel\_indicator** to 1.
+
+**splice\_event\_id**: This is specified in [ITU-T J.181]. See the discussion in clause 11.1 for further details. The injector retains this value until the time indicated by the *timestamp()* is reached.
+
+**unique\_program\_id**: This is specified in [ITU-T J.181]. See the discussion in clause 12.2 for further details.
+
+**pre\_roll\_time**: A 16-bit field giving the time to the insertion point in milliseconds. This field is ignored for **splice\_insert\_type** values other than *spliceStart\_normal* and *spliceEnd\_normal*. If zero (and component mode is not in use), the injector should set the **splice\_immediate\_flag** to 1 in the resulting ITU-T J.181 *splice\_info\_section*. The minimum non-zero **pre\_roll\_time** is defined in clause 12.3.
+
+**break\_duration**: A 16-bit field giving the duration of the insertion in tenths of seconds. If zero, the injector will not set a duration. This field is ignored for **splice\_insert\_type** values other than *spliceStart\_normal* and *spliceStart\_immediate*.
+
+**avail\_num**: An 8-bit field giving identification for a specific *avail* within the current **unique\_program\_id**. The value follows the semantics specified in [ITU-T J.181] for this field. It may be zero to indicate its non-usage.
+
+**avails\_expected**: An 8-bit field giving a count of the expected number of individual *avails* within the current viewing event. If zero, it indicates that **avail\_num** has no meaning.
+
+**auto\_return\_flag**: If this field is non-zero and a non-zero value of **break\_duration** is present, then the **auto\_return** field in the resulting ITU-T J.181 section will be set to one. This field is ignored for **splice\_insert\_type** values other than *spliceStart\_normal* and *spliceStart\_immediate*.
+
+#### 9.3.1.2 Detailed discussion of message syntax and semantics
+
+The automation system will only need to send a single *splice\_request* message per splice unless there is a compelling reason to do so otherwise (such as video conveyance or cancellation). The injector, on the other hand, may generate several ITU-T J.181 *splice\_info\_sections* per splice on a normal basis. This is in keeping with the recommendations of [b-ANSI/SCTE 67]. To permit such action, the AS must send the single *splice\_request* message well in advance of the minimum **pre\_roll\_time** (for example, 10 seconds instead of the minimum 4).
+
+If a *spliceStart\_normal* request with a non-zero value of **pre\_roll\_time** which is less than the minimum allowed value is received, the injector shall issue the resultant ITU-T J.181 *splice\_info\_section* and return an error code of "pre-roll too small".
+
+If the AS has issued a *splice\_cancel* **splice\_insert\_type** request to the injector, and the indicated request was issued with a time delay, then the injector can use the **splice\_event\_id** field to determine if it should simply not issue the resulting ITU-T J.181 section related to that *message\_number*, or if it needs to issue a *splice\_insert()* section with the **splice\_event\_cancel\_indicator** set to '1'.
+
+If a splice is to be cancelled, then the **splice\_insert\_type** value would be *splice\_cancel*, the AS supplies the correct value for **splice\_event\_id** and the injector will set the **splice\_event\_cancel\_indicator** to 1 in the resulting splice\_info\_section. If a splice is to be cancelled, then the AS is responsible for ensuring that a cancellation is sent before the indicated insertion point is reached.
+
+If an early return is to be signalled, the **splice\_insert\_type** value would be *spliceEnd\_immediate*. The splice\_info\_section that the injector will send as a result has **out\_of\_network\_indicator** set to 0 and **splice\_immediate\_flag** set to 1.
+
+For long-form insertions where a duration is either not known or the return is to be explicitly signalled, the **break\_duration** field is set to 0 and a non-zero **pre\_roll\_time** value is given. At the return point, a *spliceEnd\_normal* request is sent, again with a non-zero value in the **pre\_roll\_time** field. In this case, the injector may also choose to send several return splice\_info\_sections in a manner analogous to *spliceStart\_normal*.
+
+### 9.3.2 Mapping of splice\_request fields into ITU-T J.181 splice\_insert() fields (informative)
+
+The following table summarizes the settings resulting from the combination of the **splice\_insert\_type** and the other parameters in the splice\_request\_data(). Duration\_flag is set to one if a non-zero **break\_duration** is given.
+
+**Table 9-7 – splice\_insert\_type corresponding splice\_insert() field settings (informative)**
+
+| This API              |       | Resulting ITU-T J.181 splice_insert() structure |                          |               |                       |                         |
+|-----------------------|-------|-------------------------------------------------|--------------------------|---------------|-----------------------|-------------------------|
+| splice_insert_type    | Value | splice_event_cancel_indicator                   | out_of_network_indicator | duration_flag | splice_immediate_flag | auto_return_flag (Note) |
+| Reserved              | 0     | n/a                                             | n/a                      | n/a           | n/a                   | n/a                     |
+| spliceStart_normal    | 1     | 0                                               | 1                        | 0 or 1        | 0                     | 0 or 1                  |
+| spliceStart_immediate | 2     | 0                                               | 1                        | 0 or 1        | 1                     | 0 or 1                  |
+| spliceEnd_normal      | 3     | 0                                               | 0                        | 0             | 0                     | n/a (0)                 |
+| spliceEnd_immediate   | 4     | 0                                               | 0                        | 0             | 1                     | n/a (0)                 |
+| splice_cancel         | 5     | 1                                               | n/a (0)                  | 0             | n/a (0)               | n/a (0)                 |
+
+NOTE – The auto\_return\_flag is within the ITU-T J.181 break\_duration() structure, not the splice\_insert() structure, in which all of the other parameters are defined.
+
+A more detailed drawing is shown below, illustrating the mapping between the fields contained in a single\_operation\_message() (with opID of splice\_request and the resulting ITU-T J.181 splice\_info\_section()).
+
+Please note that one or more descriptors are built in response to a splice\_request, to which the user may add by use of an insert\_avail\_descriptor request (see clause 9.8.4), insert\_descriptor request (see clause 9.8.5), an insert\_DTMF\_descriptor request (see clause 9.8.6), or an insert\_segmentation\_descriptor request (see clause 9.8.7).
+
+![](7ae836e598020d937ed1478c2ef13025_img.jpg)
+
+| SCTE 104                     |                                | SCTE 35                       |                        |
+|------------------------------|--------------------------------|-------------------------------|------------------------|
+| multiple_operation_message() |                                | splice_info_section() {       |                        |
+| Reserved                     | 0xFFFF                         | table_id                      | 0xFC                   |
+| messageSize                  |                                | section_syntax_indicator      | 0                      |
+| protocol_version             |                                | private_indicator             | 0                      |
+| AS_index                     |                                | section_length                |                        |
+| message_number               |                                | protocol_version              |                        |
+| DPI_PID_index                |                                | encrypted_packet              |                        |
+| SCTE35_protocol_version      | ←                              | encryption_algorithm          |                        |
+| timestamp()                  |                                | pts_adjustment                |                        |
+| num_ops                      | 1                              | cw_index                      |                        |
+| opID                         | 0x0101 = splice_request_data() | splice_command_length         |                        |
+| data_length                  |                                | splice_command_type           | 0x05 = splice_insert() |
+| splice_request_data() {      |                                | splice_insert() {             |                        |
+| splice_insert_type           | 0x01 = spliceStart_normal ←    | splice_event_id               |                        |
+| splice_event_id              | ←                              | splice_event_cancel_indicator |                        |
+| unique_program_id            | ←                              | out_of_network_indicator      |                        |
+| pre_roll_time                | ←                              | program_splice_flag           |                        |
+| break_duration               | ←                              | duration_flag                 | 1                      |
+| avail_num                    | ←                              | splice_immediate_flag         |                        |
+| avails_expected              | ←                              | splice_time() {               |                        |
+| auto_return_flag             | ←                              | time_specified_flag           | 1                      |
+| }                            |                                | pts_time                      |                        |
+|                              |                                | }                             |                        |
+|                              |                                | break_duration() {            |                        |
+|                              |                                | auto_return                   |                        |
+|                              |                                | duration                      |                        |
+|                              |                                | }                             |                        |
+|                              |                                | unique_program_id             |                        |
+|                              |                                | avail_num                     |                        |
+|                              |                                | avails_expected               |                        |
+|                              |                                | }                             |                        |
+|                              |                                | descriptor_loop_length        |                        |
+|                              |                                | avail_descriptor() {          |                        |
+|                              |                                | splice_descriptor_tag         |                        |
+|                              |                                | descriptor_length             |                        |
+|                              |                                | identifier                    |                        |
+|                              |                                | provider_avail_id             |                        |
+|                              |                                | }                             |                        |
+|                              |                                | for(i=0; i<N2; i++) {         |                        |
+|                              |                                | alignment_stuffing            |                        |
+|                              |                                | }                             |                        |
+|                              |                                | CRC_32                        |                        |
+|                              |                                | }                             |                        |
+
+J.287(14)\_F9-1
+
+**Figure 9-1 – multiple\_operation\_message() to ITU-T J.181 section field mapping (informative)**
+
+## 9.4 Encryption support (normative)
+
+The method provided by this API for the support of encrypted ITU-T J.181 splice\_info\_sections assumes that the encryption will be done by the injector. As a result, the PAMS will need to supply a number of additional items of provisioning data related to the encryption method to be used, such as the key information (which may also be provided by the AS using this API) and so forth. Please refer to clause 11 of [ITU-T J.181] for additional information.
+
+The injector which supports encryption shall contain 256 control word "slots". If a slot has been filled with a control word set (three 64-bit numbers), then encryption can take place. If the AS references a slot without a control word defined, then the entire generation of the associated splice\_info\_section shall be aborted and an error returned to the AS or an alarm raised by the injector.
+
+### 9.4.1 Encryption control word support
+
+The API specifies the basic messages to define and maintain the current (and next) control words. Compliant implementations which support encryption may choose not to support these messages (defined in clauses 9.4.3 and 9.4.4) and instead have the PAMS manage all control words.
+
+These AS requests carry sensitive security information. If these requests are used, then normal security precautions should be implemented (such as password protection on login screens and physical access restrictions to control areas). The assumption in using these messages is that the link used to carry the messages is secure and is not easily compromised. Further protection for these requests, such as encrypting the requests, is outside the scope of this Recommendation.
+
+### 9.4.2 The encrypted DPI request
+
+The encrypted DPI message is used for applications that wish to use the built-in security capabilities of [ITU-T J.181] under the direction of the automation system. This message is sent in the clear, and the resulting ITU-T J.181 section will be encrypted by the injector before being formatted and placed in the output multiplex.
+
+The actual control words to use by the injector must have been previously provisioned by the PAMS or by the AS (via the `update_ControlWord` request in clause 9.4.3) for the particular control word index, or the resulting ITU-T J.181 `splice_info_section()` will not be placed in the outgoing TS, the `data()` discarded, and an error code returned by the injector. In a unidirectional communication system, the error return path shall be notification of the PAMS operator.
+
+This is a supplemental usage request and must follow the associated `splice_request_data()` in the `data()` structure of the `multiple_operation_message()` (see clause 8.2.3) for which it applies. If `component_mode_DPI_data()` structures are also present in the `multiple_operation_message` `data()` structure, then the `encrypted_DPI_data()` follows the final occurrence of `component_mode_DPI_data()`. When this request is present, the **encrypted\_packet** bit shall be set in the resulting `splice_info_section()`.
+
+**Table 9-8 – encrypted\_DPI\_request\_data**
+
+| Syntax                                      | Bytes | Type   |
+|---------------------------------------------|-------|--------|
+| <code>encrypted_DPI_request_data() {</code> |       |        |
+| <code>encryption_algorithm</code>           | 1     | uimsbf |
+| <code>CW_index</code>                       | 1     | uimsbf |
+| <code>}</code>                              |       |        |
+
+#### 9.4.2.1 Semantics of fields in encrypted\_DPI\_request\_data()
+
+**encryption\_algorithm:** This field carries the value of the 6-bit field defined in [ITU-T J.181].
+
+**CW\_index:** An 8 bit unsigned integer which conveys which control word (key) is to be used to encrypt and decrypt the message.
+
+### 9.4.3 update\_controlWord request AS ==> IJ
+
+This is a control usage request, and serves to set up an authorization group. Changing the control words for a service is expected to be a relatively rare occurrence. This request allows the encryption group to be downloaded and then used by subsequent `encrypted_DPI` requests. This message will replace any existing control words in the specified index position.
+
+In some architectures, the control of encryption services may be done by the PAMS rather than the AS. In these cases, this message would not be used, since it would overwrite the control words downloaded by the system controller. The automation system may still need to know which messages
+
+are to be encrypted and which CW\_index to assign to specific messages. The mechanism for doing so is not defined in this Recommendation.
+
+**Table 9-9 – update\_ControlWord\_data**
+
+| Syntax                      | Bytes | Type   |
+|-----------------------------|-------|--------|
+| update_ControlWord_data() { |       |        |
+| CW_index                    | 1     | uimsbf |
+| CW_A                        | 8     | uimsbf |
+| CW_B                        | 8     | uimsbf |
+| CW_C                        | 8     | uimsbf |
+| }                           |       |        |
+
+#### 9.4.3.1 Semantics of fields in update\_ControlWord\_data()
+
+**CW Index:** This field specifies the control word index used to reference the control word database. This field may range from 0 to 255. The index sent indicates which of the 256 control word set should be replaced in the injector's control word database.
+
+Each control word set is 3 64-bit numbers. The two single DES encryption modes only use **CW\_A**, while Triple-DES requires all 3 64-bit control words. All 3 fields are always sent, but if Triple-DES is not used, **CW\_B** and **CW\_C** shall be zeros.
+
+**CW\_A:** ControlWord\_A, a 64-bit value which is always used. In the case of the two single DES encryption modes, **CW\_A** is used alone (**CW\_B** and **CW\_C** are zero filled), while Triple-DES requires all 3 64-bit control words.
+
+**CW\_B:** This is the second 64-bit number sent as a control word. This value is normally zero unless Triple-DES encryption is utilized, in which case it carries the second of the three control word values.
+
+**CW\_C:** This is the third 64-bit number sent as a control word. This value is normally zero unless Triple-DES encryption is utilized, in which case it carries the third of the three control word values.
+
+### 9.4.4 delete\_ControlWord request AS ==> IJ
+
+This is a control usage request. If an encryption group is no longer required, then this request can be sent to remove the control words from the injector's database. This is only really necessary if one wishes to prevent messages from being sent with this control word, since empty control word index slots result in an alarm if an attempt is made to use it.
+
+The injector shall not produce an alarm if an undefined control word is deleted. This allows the AS to delete all control words without actually knowing which control words are present, so the control word database can be reinitialized.
+
+In some architectures, the control of encryption services may be done by the PAMS rather than an automation controller. In these cases, this message would not be used, since it would delete the control words downloaded by the PAMS.
+
+**Table 9-10 – delete\_ControlWord\_data**
+
+| Syntax                      | Bytes | Type   |
+|-----------------------------|-------|--------|
+| delete_ControlWord_data() { |       |        |
+| CW_index                    | 1     | uimsbf |
+| }                           |       |        |
+
+#### 9.4.4.1 Semantics of fields in delete\_ControlWord\_data()
+
+**CW Index:** This field specifies the control word index used to reference the control word database. This field ranges from 0 to 255.
+
+## 9.5 Component mode support
+
+### 9.5.1 component mode DPI request
+
+The component mode DPI request is used for applications that wish to splice into some of the elementary streams of a program, and not others. This is an advanced method of DPI control that requires detailed knowledge of the structure of the program elements that exists in the same program as this DPI splice\_info\_section.
+
+It is a supplemental type request (see clause 8.3.1) and must follow the splice\_request\_data() for which it applies within the data() structure of the multiple\_operation\_message (see clause 8.2.3).
+
+The presence of this request changes fundamental syntactic elements in the resulting ITU-T J.181 splice\_info\_section() as the request will force component mode rather than program mode operation in the splicer.
+
+**Table 9-11 – component\_mode\_DPI\_request\_data**
+
+| Syntax                              | Bytes | Type   |
+|-------------------------------------|-------|--------|
+| component_mode_DPI_request_data() { |       |        |
+| for(i=0; i<N; i++) {                |       |        |
+| component_tag                       | 1     | uimsbf |
+| component_preroll                   | 2     | uimsbf |
+| }                                   |       |        |
+| }                                   |       |        |
+
+#### 9.5.1.1 Semantics of fields in component\_mode\_DPI\_request\_data()
+
+**component\_tag:** This field contains the associated component tag for one of the elementary streams to be spliced. The loop provides a complete list of spliced elementary streams and the time at which the splice should occur.
+
+**component\_preroll:** The overall request time stamp provides the exact time to process the message. In component mode, each component (i.e., elementary stream PID) has a unique time at which its splice is to occur. The actual ITU-T J.181 time stamp can be calculated by adding the pre-roll time to the timestamp() reference point.
+
+When operating in component mode splicing, the value of **pre\_roll\_time** given in the corresponding splice\_request message is not used.
+
+This field is expressed in milliseconds.
+
+## 9.6 Response messages
+
+### 9.6.1 general\_response message IJ ==> AS
+
+The **general\_response** message conveys back a **result** code. This is a basic message.
+
+**Table 9-12 – general\_response\_data**
+
+| Syntax                         | Bytes | Type |
+|--------------------------------|-------|------|
+| general_response_data() {<br>} |       |      |
+
+This response message is sent following the receipt of the following messages:
+
+**Table 9-13 – general responses**
+
+| Request             | Description                                                                                                              |
+|---------------------|--------------------------------------------------------------------------------------------------------------------------|
+| update_ControlWord  | This allows the AS to download a new CW for use in encrypted messages.                                                   |
+| delete_Control_Word | This allows the AS to delete an active CW. Once deleted, an injector can flag an error if any attempt is made to use it. |
+
+### 9.6.2 inject\_response message IJ ==> AS
+
+The **inject\_response** message conveys back the **message\_number** from the **multiple\_operation\_message()** structure (clause 8.2.3) to which it is responding. This message can contain a result code if appropriate. This is a basic message.
+
+A proxy device may respond with a "Proxy Response" **result** code (see Table 14-1). This permits the automation system, should it desire to do so, to track whether or not a given injector is served by a proxy device or a direct connection.
+
+**Table 9-14 – inject\_response data**
+
+| Syntax                                          | Bytes | Type   |
+|-------------------------------------------------|-------|--------|
+| inject_response_data() {<br>message_number<br>} | 1     | uimsbf |
+
+#### 9.6.2.1 Semantics of fields in inject\_response\_data()
+
+**message\_number:** The **message\_number** of the **multiple\_operation\_message()** that is being acknowledged.
+
+The **inject\_response** message is sent following the receipt of the following messages:
+
+**Table 9-15 – inject\_responses**
+
+| Request                         | Description                                                                                                            |
+|---------------------------------|------------------------------------------------------------------------------------------------------------------------|
+| splice_request                  | Acknowledgement for splice_request – returned to the AS immediately to acknowledge receipt of the command              |
+| time_signal_request             | Acknowledgement for a time signal request – returned to the AS immediately to acknowledge receipt of the command       |
+| splice_null_request             | Acknowledgement for a splice null request – returned to the AS immediately to acknowledge receipt of the command       |
+| proprietary_command_request     | Acknowledgement for proprietary command request – returned to the AS immediately to acknowledge receipt of the command |
+| start_schedule_download_request | Indicates to an injector that it should start collecting schedule information                                          |
+| schedule_definition_request     | Used to download a single schedule entry into the injector's database                                                  |
+| schedule_component_mode request | Used as a supplemental command for "Schedule Definition" to indicate that a component splice is being scheduled        |
+| transmit_schedule_request       | The automation system uses this command to tell an injector to send the accumulated schedule information.              |
+
+### 9.6.3 inject\_complete response IJ ==> AS
+
+The **inject\_complete\_response** message is sent once when the injector finishes issuing all ITU-T J.181 splice\_info\_sections for a given normal request operation and conveys back the **message\_number** from the multiple\_operation\_message() structure (clause 8.2.3) to which it is responding. If a normal request does not result in the issuing of any ITU-T J.181 splice\_info\_sections, then this response is not sent. The value of the **message\_number** variable is now free to be reused.
+
+A single **inject\_complete\_response** message is sent regardless of the number of operations contained within a given multiple\_operation\_message() structure. The **inject\_complete\_response** message contains a count which indicates the number of ITU-T J.181 splice\_info\_sections issued by an injector in response to the previous **splice\_request**. A result value of "Successful Response" will normally be expected for this message. See Table 14-1 for the various result codes.
+
+**Table 9-16 – inject\_complete response data**
+
+| Syntax                            | Bytes | Type   |
+|-----------------------------------|-------|--------|
+| inject_complete_response_data() { |       |        |
+| message_number                    | 1     | uimsbf |
+| cue_message_count                 | 1     | uimsbf |
+| }                                 |       |        |
+
+A proxy device may respond with a "Proxy Response" **result** code (see Table 14-1). This permits the automation system, should it desire to do so, to track whether or not a given injector is served by a proxy device or a direct connection.
+
+#### 9.6.3.1 Semantics of fields in inject\_complete\_response\_data()
+
+**message\_number:** The message number of the multiple\_operation\_message() that has completed processing.
+
+**cue\_message\_count:** This is an integer value that specifies the count of ITU-T J.181 splice\_info\_sections sent by an injector. This value may be logged by the automation system if
+
+desired. The injector will clear the **cue\_message\_count** after each inject\_complete\_response is sent to the automation system.
+
+The inject\_complete\_response message is sent following the injection of the ITU-T J.181 section in response to the following messages:
+
+**Table 9-17 – inject\_complete\_responses**
+
+| Request                     | Description                                                                                                                                                                                                                                                       |
+|-----------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| splice_request              | Acknowledgement for splice request – returned after the DPI message has been injected into the transport. May be returned immediately after the splice response if immediate mode timing is used. May be delayed if time-stamped processing is used.              |
+| time_signal_request         | Acknowledgement for time signal request – returned after the DPI message has been injected into the transport. May be returned immediately after the splice response if immediate mode timing is used. May be delayed if time-stamped processing is used.         |
+| splice_null_request         | Acknowledgement for splice null request – returned after the DPI message has been injected into the transport. May be returned immediately after the splice response if immediate mode timing is used. May be delayed if time-stamped processing is used.         |
+| proprietary_command_request | Acknowledgement for proprietary command request – returned after the DPI message has been injected into the transport. May be returned immediately after the splice response if immediate mode timing is used. May be delayed if time-stamped processing is used. |
+| transmit_schedule_request   | Indicates the schedule data has been injected into the transport                                                                                                                                                                                                  |
+
+## 9.7 ITU-T J.181 splice\_schedule() support requests
+
+The DPI schedule requests may exist in multiple sections within a transport. Each section contains a descriptor loop. All sections of a given schedule will contain the exact same descriptors.
+
+If the avail descriptor is to be present, then it is filled from the data provided in the start schedule download request. This allows each section to be built as the data is being downloaded.
+
+If other descriptors are to be present, those requests follow in data(), and the insert\_descriptor requests must be present in the same message that carries this request. Those descriptors will then be duplicated in each real section generated. The injector must have enough memory to hold the descriptors, as well as the schedule data.
+
+### 9.7.1 start schedule download request AS ==> IJ
+
+[ITU-T J.181] allows for a schedule of avail times to be broadcast. This request readies the injector to accept one or more schedule\_definition\_data() requests prior to transmission. Since a schedule can potentially have a large amount of data, provision has been made to download the data in smaller pieces.
+
+The start schedule download message permits the generation of an ITU-T J.181 avail\_descriptor. It is a normal type message. The injector must allocate sufficient memory to permit the accumulation of the maximum amount of section data specified by [ITU-T J.181]. A splice\_request is not required in conjunction with splice\_schedule.
+
+If the schedule request is intended to be encrypted before being sent, then the Encrypted\_DPI\_data() structure must be included in the same multiple\_operation\_message data() structure (see clause 8.2.3) as this start\_schedule\_download\_data() structure. In this case *ONLY*, it must be placed in the data() structure before the start\_schedule\_download\_data() structure is placed in the data() structure.
+
+By setting up the encryption before downloading the data, any intermediate sections that might be created can also be encrypted.
+
+The ITU-T J.181 `splice_info_section()` structure only allows one descriptor loop for an entire schedule `splice_info_section`. Therefore, any supplemental requests that generate descriptors must be attached to the start schedule request. These descriptors will then be inserted in all `splice_info_section` generated as a result of the schedule download.
+
+**Table 9-18 – start\_schedule\_download\_request\_data**
+
+| Syntax                                                   | Bytes | Type   |
+|----------------------------------------------------------|-------|--------|
+| <code>start_schedule_download_request_data() {</code>    |       |        |
+| <code>num_provider_avails</code>                         | 1     | uimsbf |
+| <code>for (i=0 ;i&lt; num_provider_avails; i++) {</code> |       |        |
+| <code>provider_avail_id</code>                           | 4     | uimsbf |
+| <code>}</code>                                           |       |        |
+| <code>}</code>                                           |       |        |
+
+#### 9.7.1.1 Semantics of fields in start\_schedule\_download\_request\_data()
+
+**num\_provider\_avails:** If this field is zero, then the provider avail id field is not being used and the value should be ignored and no `avail_descriptor` will be created.
+
+If this field is non-zero, then the provider avail id field(s) must contain valid data.
+
+**provider\_avail\_id:** This is an optional 32-bit number which will be inserted into the ITU-T J.181 `splice_info_section()` `avail_descriptor`.
+
+Please refer to clause 8.3.1 of [ITU-T J.181] for more information.
+
+### 9.7.2 schedule definition request AS ==> IJ
+
+This request allows a single `avail` definition to be collected by the injector. Using the overall message structure, it is possible to deliver multiple `splice point` definitions in the same resultant `splice_info_section()`. This request will be issued once per `splice` event to be included in that `splice_info_section()`.
+
+A `splice` definition being transmitted must be contained within an ITU-T J.181 `splice_info_section()` structure. This section has a limited size of 4096 bytes, although some implementations may have lower maximum sizes. If a schedule being transmitted exceeds the local maximum memory allocated, it is possible that the first resultant section could be formatted, packetized and placed in the transport stream before the `transmit_schedule` request is sent to force transmission and thus make space for more schedule data in the local memory of the injector.
+
+This is a supplemental request and must follow a `start_schedule_download_data()` in the `data()` structure of a `multiple_operation_message()`.
+
+**Table 9-19 – schedule\_definition\_data**
+
+| Syntax                       | Bytes | Type   |
+|------------------------------|-------|--------|
+| schedule_definition_data() { |       |        |
+| splice_schedule command      | 1     | uimsbf |
+| splice_event_id              | 4     | uimsbf |
+| time()                       | 4     |        |
+| unique_program_id            | 2     | uimsbf |
+| auto_return                  | 1     | uimsbf |
+| break_duration               | 2     | uimsbf |
+| avail_num                    | 1     | uimsbf |
+| avails_expected              | 1     | uimsbf |
+| }                            |       |        |
+
+#### 9.7.2.1 Semantics of fields in schedule\_definition\_data()
+
+**splice\_schedule command:** This field indicates if the associated ITU-T J.181 splice\_schedule() section generated will be a splice insert (away from the network) or a splice return to the network. A cancellation may also be signalled.
+
+**Table 9-20 – splice\_schedule command type assigned values**
+
+| splice_schedule_command_type | Value assigned |
+|------------------------------|----------------|
+| reserved                     | 0              |
+| splice_insert                | 1              |
+| reserved                     | 2              |
+| splice_return                | 3              |
+| reserved                     | 4              |
+| splice_cancel                | 5              |
+
+**splice\_event\_id:** This is a 32-bit number that will be coded into the splice\_event\_id in the final ITU-T J.181 splice\_info\_section.
+
+**time():** See clause 12.4. A 32-bit unsigned integer quantity representing the time of the signalled splice event as the number of seconds since 00 hours UTC, January 6, 1980, with the count of intervening leap seconds included. See [b-IETF RFC 1305] for further information.
+
+**unique\_program\_id:** This is a 16-bit field as defined by [ITU-T J.181].
+
+**auto\_return:** If this field is non-zero, then the **auto\_return** field in the resulting break\_duration() of the ITU-T J.181 section will be set to one.
+
+**break\_duration:** A 16-bit field giving the duration of the insertion in tenths of seconds. If **break\_duration** is set to zero, then the resulting ITU-T J.181 splice\_schedule() section will not include the break\_duration() and the flags **auto\_return** and **duration\_flag** will be set to zero.
+
+**avail\_num:** This is an 8-bit number indicating which avail within the program is currently being described (see [ITU-T J.181]). It will be coded as a decimal number from 1 to 255. A value of zero indicates that the avail fields are not being used. If this field is coded as zero, so should the **avails\_expected** field.
+
+**avails\_expected:** This is an 8-bit number indicating how many avails to expect within the program currently being described (see [ITU-T J.181]). It will be coded as a decimal number from 1 to 255. A
+
+value of 0 indicates that the avail fields are not being used. If this field is coded as zero, so should the **avail\_num** field.
+
+### 9.7.3 The schedule component mode request AS ==> IJ
+
+The **schedule\_component\_mode** request is used for applications that wish to splice into some of the elementary streams of a program, and not others. This is an advanced method of DPI control that requires detailed knowledge of the structure of the program elements that exist in the same program as this DPI message. If component mode is used for a specific avail, then this structure may be delivered along with the associated **schedule\_definition\_data()** structure to define the components that will be spliced in that avail.
+
+**Table 9-21 – schedule\_component\_request\_mode**
+
+| Syntax                                                                                                                         | Bytes          | Type   |
+|--------------------------------------------------------------------------------------------------------------------------------|----------------|--------|
+| <pre> schedule_component_mode_request_data() {     for(i=0; i&lt;N; i++) {         component_tag         time()     } } </pre> | <p>1<br/>*</p> | uimsbf |
+
+#### 9.7.3.1 Semantics of fields in schedule\_component\_mode\_request\_data()
+
+**component\_tag**: This field contains the associated component tag for one of the elementary streams to be spliced. The loop provides a complete list of spliced elementary streams and the time at which the splice should occur.
+
+**time()**: See clause 12.4. A 32-bit unsigned integer quantity representing the time of the signalled splice event as the number of seconds since 00 hours UTC, January 6, 1980, with the count of intervening leap seconds included. See [b-IETF RFC 1305] for further information.
+
+### 9.7.4 transmit\_schedule request
+
+This is a normal usage request. When this request is processed, any schedule data saved in local memory is packetized and transmitted at the time indicated.
+
+A downloaded schedule is not remembered after it has been transmitted, and the injector may immediately free up allocated local memory. The automation device is responsible for retransmitting up-to-date schedule information when required.
+
+**Table 9-22 – transmit\_schedule\_request\_data**
+
+| Syntax                                                       | Bytes | Type   |
+|--------------------------------------------------------------|-------|--------|
+| <pre> transmit_schedule_request_data() {     cancel } </pre> | 1     | uimsbf |
+
+#### 9.7.4.1 Semantics of fields in transmit\_schedule\_request\_data()
+
+**cancel**: This flag is used to cancel any downloaded data and abort the transmission of the schedule in progress. A value of zero is normal, and it indicates that the downloaded data can be transmitted at the time that the time stamp indicates. Any non-zero value indicates that the download should be cancelled.
+
+If this request is cancelled before being processed, then the entire schedule downloaded is also discarded. The effect is the same as if this request was sent with the cancel bit set.
+
+## 9.8 Miscellaneous requests
+
+### 9.8.1 time signal request AS ==> IJ
+
+This is a normal request which will be generated and transmitted at the time indicated by the `timestamp()` field of the `multiple_operation_message()` structure. This request will normally be accompanied by one or more `insert_descriptor` requests.
+
+**Table 9-23 – time\_signal\_request\_data**
+
+| Syntax                                                                | Bytes | Type   |
+|-----------------------------------------------------------------------|-------|--------|
+| <code>time_signal_request_data() {<br/>    pre-roll_time<br/>}</code> | 2     | uimsbf |
+
+#### 9.8.1.1 Semantics of fields in time\_signal\_request\_data()
+
+**pre-roll\_time:** The splice `splice_info_section` may be sent by the automation system well in advance of when it is required. In order to support the repeated sending of the same `splice_info_section` and to support multiple sections being outstanding simultaneously, this request supports the preloading of its parameters. The `timestamp()` indicates the time to process the `splice_info_section`. The `pre-roll` field indicates the amount of time, in milliseconds, after being processed that the action will occur. For the `time_signal_request()`, this is the pre-roll for the associated descriptors. If this request arrives after the indicated time, the `splice_info_section` is sent as soon as possible.
+
+The time stamp field can indicate immediate processing (and therefore uses relative timing) or delayed processing (which uses exact timing). In all cases, the signalling point is calculated relative to the time the request is processed. The `pre-roll` field determines the exact delay period for the splice point relative to the request being processed.
+
+If this request is processed immediately on arrival, then the physical insertion of the time signal request is as soon as it is received.
+
+In the case of an exact time stamp using a UTC time code, VITC time code<sup>1</sup> or GPI triggering<sup>2</sup>, the request is processed at the indicated time.
+
+In the case when a component mode request is used to modify this basic request, the overall `pre-roll` time is not used. That is, this field is only used when the DPI `splice_info_section` produced is for a program mode splice. For component mode splicing, each component will have its own time stamp.
+
+<sup>1</sup> VITC time code cannot be used to indicate the exact splice point. A common practice is to use the time code recorded with the programme rather than a 24-hour studio time code. This means that the VITC time code is discontinuous around the start/end of the program. It would be impossible to determine the proper splice point since one cannot simply subtract the `pre-roll` time from the desired VITC time. Doing so may bring the VITC time cross a discontinuity and would never match a time found on the input.
+
+<sup>2</sup> GPI (General purpose input) is generally used when co-timing to analogue cue tone systems. Using a third-party box, the analogue cue tone can be converted to a GPI pulse. This would occur at the insertion point of the cue tone, not the splice point. So, the pulse is occurring at the `pre-roll` time before the actual splice point.
+
+### 9.8.2 splice null request
+
+This is a normal usage request. When this request is processed, an ITU-T J.181 splice\_null() splice\_info\_section will be generated and transmitted at the time indicated by the time stamp field. This request will normally be accompanied by one or more insert\_descriptor requests.
+
+**Table 9-24 – splice\_null\_request\_data**
+
+| Syntax                            | Bytes | Type |
+|-----------------------------------|-------|------|
+| splice_null_request_data() {<br>} |       |      |
+
+### 9.8.3 inject section data request AS ==> IJ
+
+This is a normal usage request. When this request is processed, the image will be copied into the command structure of the associated ITU-T J.181 splice\_info\_section being created. Some supplemental requests, such as an insert descriptor request or encrypted\_DPI request may be used with this request.
+
+**Table 9-25 – inject\_section\_data\_request**
+
+| Syntax                          | Bytes | Type   |
+|---------------------------------|-------|--------|
+| inject_section_data_request() { |       |        |
+| SCTE35_command_length           | 2     | uimsbf |
+| SCTE35_protocol_version         | 1     | uimsbf |
+| SCTE35_command_type             | 1     | uimsbf |
+| SCTE35_command_contents()       | *     |        |
+| }                               |       |        |
+
+#### 9.8.3.1 Semantics of fields in inject\_section\_data\_request()
+
+**SCTE35\_command\_length:** This field encodes the number of bytes in the SCTE35\_command\_contents() structure.
+
+**SCTE35\_protocol\_version:** When the ITU-T J.181 splice\_info\_section() is created, the protocol version field in the splice info section will be filled in with this value. This could allow a compatible method of delivering commands defined in future revisions of [ITU-T J.181] using older versions of this protocol.
+
+**SCTE35\_command\_type:** This field will fill in the value of the **splice\_command\_type** field in the ITU-T J.181 splice\_info\_section() being created.
+
+**SCTE35\_command\_contents():** This is a complete binary image of the ITU-T J.181 splice\_info\_section() being created, following the **splice\_command\_type** field up to, but not including, the **descriptor\_loop\_length** field.
+
+### 9.8.4 insert\_avail\_descriptor request AS ==> IJ
+
+This is a supplemental usage request. When this request is processed, an avail\_descriptor() shall be added to the descriptor loop of the associated ITU-T J.181 splice\_info\_section being created. The normal request to which it applies must exist earlier in the same data() buffer.
+
+**Table 9-26 – insert\_avail\_descriptor\_request\_data**
+
+| Syntax                                                                                                                                     | Bytes                  | Type                             |
+|--------------------------------------------------------------------------------------------------------------------------------------------|------------------------|----------------------------------|
+| insert_avail_descriptor_request_data() {<br>num_provider_avails<br>for (i=0 ;i< num_provider_avails; i++) {<br>provider_avail_id<br>}<br>} | <br>1<br><br>4<br><br> | <br>uimsbf<br><br>uimsbf<br><br> |
+
+#### **9.8.4.1 Semantics of fields in insert\_avail\_descriptor\_request\_data()**
+
+**num\_provider\_avails:** If this field is zero, then the provider\_avail\_id field is not being used and the value shall be ignored.
+
+If this field is non-zero, then the **num\_provider\_avails** field is the repetition count for the **provider\_avail\_id** field. Also, the injector must include an avail\_descriptor() in the DPI splice\_info\_section created.
+
+**provider\_avail\_id:** This is an optional 32-bit field which may be inserted into the resulting ITU-T J.181 splice\_info\_section. If the value of **num\_provider\_avails** is zero, this field shall be ignored and no avail\_descriptor() shall be created.
+
+### **9.8.5 insert\_descriptor request AS ==> IJ**
+
+This is a supplemental usage request. When this request is processed, the descriptor image will be copied into the descriptor loop of the associated ITU-T J.181 splice\_info\_section being created. One of the normal requests must exist earlier in the same data() buffer and these descriptors will be added to any ITU-T J.181 section generated by that normal request.
+
+**Table 9-27 – insert\_descriptor\_request\_data**
+
+| Syntax                                                                                                                          | Bytes                  | Type                       |
+|---------------------------------------------------------------------------------------------------------------------------------|------------------------|----------------------------|
+| insert_descriptor_request_data() {<br>descriptor_count<br>for(i=0; i< descriptor_count ; i++) {<br>descriptor_image()<br>}<br>} | <br>1<br><br>*<br><br> | <br>uimsbf<br><br><br><br> |
+
+#### **9.8.5.1 Semantics of fields in insert\_descriptor\_request\_data()**
+
+**descriptor\_count:** This field encodes the number of descriptors following.
+
+**descriptor\_image:** This field carries a complete image of a standard ITU-T J.181 descriptor, which follows MPEG-2 rules and has its length as the second byte of the descriptor. This request is used to inject proprietary, or future standard descriptors into a request without the need for specific knowledge of the contents of the descriptor to be injected. For standard descriptors, the recommended method is to update this protocol to include a request for the new descriptor.
+
+### **9.8.6 insert\_DTMF\_descriptor request AS ==> IJ**
+
+This is a supplemental usage request. This request creates an image of the DTMF descriptor defined in [ITU-T J.181]. Refer to [ITU-T J.181] for details of each field in the descriptor.
+
+One specific note about this descriptor. The pre-roll field found in this descriptor is intended to be the same value as that used for the associated splice\_request. The DTMF descriptor allows for tenths of a second resolution, and the splice\_request allows millisecond resolution. One should ensure that both requests use the same pre-roll value to provide a consistent programme insertion on both analogue and digital systems.
+
+**Table 9-28 – insert\_DTMF\_descriptor\_request\_data**
+
+| Syntax                                  | Bytes | Type   |
+|-----------------------------------------|-------|--------|
+| insert_DTMF_descriptor_request_data() { |       |        |
+| pre-roll                                | 1     | uimsbf |
+| dtmf_length                             | 1     | uimsbf |
+| for(i=0; i<dtmf_length; i++) {          |       |        |
+| DTMF_char                               | 1     | uimsbf |
+| }                                       |       |        |
+| }                                       |       |        |
+
+#### 9.8.6.1 Semantics of fields in insert\_DTMF\_descriptor\_request\_data()
+
+**pre-roll:** Refer to [ITU-T J.181] for detailed usage of this field.
+
+The pre-roll time encodes the number of tenths of seconds before the splice\_point signalled in the resulting ITU-T J.181 section that a DTMF tone sequence should finish being emitted. To allow for processing time, the pre-roll signalled in the ITU-T J.181 message should be greater than this value.
+
+**dtmf\_length:** This indicates the length of the following loop in bytes.
+
+**DTMF\_char:** This field carries one character of a DTMF sequence to be output by an IRD. This field should contain one of the ASCII characters '0' to '9', '\*', '#', and 'A' to 'D'. Refer to [ITU-T J.181] for detailed usage of this field.
+
+### 9.8.7 insert\_segmentation\_descriptor request AS ==> IJ
+
+This is a supplemental usage request, and creates a segmentation descriptor defined in [ITU-T J.181]. Refer to [ITU-T J.181] for details of each field in the descriptor. The **program\_segmentation\_flag** shall be set to one in the resulting ITU-T J.181 splice\_info\_section(). If the user needs to support component mode segmentation, then an insert\_descriptor request should be used to directly format this descriptor.
+
+**Table 9-29 – insert\_segmentation\_descriptor\_request\_data**
+
+| Syntax                                          | Bytes  | Type   |
+|-------------------------------------------------|--------|--------|
+| insert_segmentation_descriptor_request_data() { |        |        |
+| segmentation_event_id                           | 4      | uimsbf |
+| segmentation_event_cancel_indicator             | 1      | uimsbf |
+| duration                                        | 2      | uimsbf |
+| segmentation_upid_type                          | 1      | uimsbf |
+| segmentation_upid_length                        | 1      | uimsbf |
+| segmentation_upid                               | varies | uimsbf |
+| segmentation_type_id                            | 1      | uimsbf |
+| segment_num                                     | 1      | uimsbf |
+| segments_expected                               | 1      | uimsbf |
+
+**Table 9-29 – insert\_segmentation\_descriptor\_request\_data**
+
+| Syntax                       | Bytes | Type   |
+|------------------------------|-------|--------|
+| duration_extension_frames    | 1     | uimsbf |
+| delivery_not_restricted_flag | 1     | uimsbf |
+| web_delivery_allowed_flag    | 1     | uimsbf |
+| no_regional_blackout_flag    | 1     | uimsbf |
+| archive_allowed_flag         | 1     | uimsbf |
+| device_restrictions          | 1     | uimsbf |
+| }                            |       |        |
+
+#### **9.8.7.1 Semantics of fields in insert\_segmentation\_descriptor\_request\_data()**
+
+**segmentation\_event\_id:** A 4 byte (32-bit) unique segmentation event identifier.
+
+**segmentation\_event\_cancel\_indicator:** A 1 byte flag that when set to '1' indicates that a previously sent segmentation event, identified by **segmentation\_event\_id**, has been cancelled.
+
+**duration:** A 2 byte (16-bit) field giving the duration of the program segment in whole seconds. A zero value is legal and results in the **segmentation\_duration\_flag** in the resulting ITU-T J.181 section being set to '0'. See **duration\_extension\_frames**.
+
+**segmentation\_upid\_type:** A 1 byte field that specifies the type of "UPID" utilized in this program. There are multiple types allowed to ensure that programmers will be able to use an id that their systems support. Refer to [ITU-T J.181] for full details.
+
+**segmentation\_upid\_length:** A 1 byte field that specifies the length in bytes of the **segmentation\_upid**.
+
+**segmentation\_upid:** A variable-length field that specifies the "UPID" value for this segment. Refer to [ITU-T J.181] for details.
+
+**segmentation\_type\_id:** A 1 byte field which designates the type of segmentation and takes the values specified in [ITU-T J.181].
+
+**segment\_num:** A 1 byte field that provides identification for a specific chapter within a **segmentation\_upid**. Refer to [ITU-T J.181] for full details.
+
+**segments\_expected:** A 1 byte field that provides a count of the expected number of individual chapters within the current segmentation event.
+
+**duration\_extension\_frames:** A 1 byte field that shall carry a value in the range from 0 to the value of the greatest integer less than frame rate, which shall be the number of frames in the fractional second not included in duration. The total duration of the program segment is duration seconds plus duration\_extension\_frames frame times. If duration is 0, this field carries no meaning.
+
+NOTE – In [ITU-T J.181], content length is described in terms of the number of ticks of a 90 kHz MPEG counter. A value in these units is calculated from duration and duration\_extension\_frames by converting duration using Section 4.1.1 of [b-SMPTE EG 40], converting duration\_extension\_frames using Section 4.2 of [b-SMPTE EG 40], and adding the resulting values.
+
+**delivery\_not\_restricted\_flag:** A 1 byte flag that when set to 1 indicates there is no need for external checks prior to delivery. A value of 0 indicates the content requires external checks. Refer to [ITU-T J.181] for full details.
+
+**web\_delivery\_allowed\_flag:** A 1 byte flag that when set to 1 indicates web delivery is allowed. Refer to [ITU-T J.181] for full details.
+
+**no\_regional\_blackout\_flag:** A 1 byte flag that when set to 1 indicates there is not a regional blackout. Refer to [ITU-T J.181] for full details.
+
+**archive\_allowed\_flag:** A 1 byte flag that when set to 1 indicates the content is archiveable. Refer to [ITU-T J.181] for full details.
+
+**device\_restrictions:** A 1 byte field which designates the type of segmentation and takes the values specified in [ITU-T J.181].
+
+### 9.8.8 proprietary\_command request AS ==> IJ
+
+This is a normal usage request, and allows for proprietary extension to the protocol. The **data\_length** field functions in the normal manner for the `data()` loop within the context of `multiple_operation_message()`.
+
+The **opID** variable for the `proprietary_command_data()` is one of the values defined in Table 8-3 for user-defined requests. In addition to using this **opID** value, each company that wishes to define proprietary ITU-T J.181 commands should register for a proprietary id value. This permits the company to create one or more proprietary commands that are uniquely theirs, each identified by their respective `proprietary_command_data()` structure.
+
+The **data\_length** field in `multiple_operation_message()` (see clause 8.2.3) must be correctly set to reflect the number of bytes utilized by the remainder of the request which follows the **data\_length** field itself. Failure to do so will result in the commands not being processed correctly.
+
+**Table 9-30 – proprietary\_command\_request\_data**
+
+| Syntax                                            | Bytes | Type   |
+|---------------------------------------------------|-------|--------|
+| <code>proprietary_command_request_data() {</code> |       |        |
+| <code>proprietary_id</code>                       | 4     | uimsbf |
+| <code>proprietary_command</code>                  | 1     | uimsbf |
+| <code>for (i=0; i&lt;data_length-5; i++) {</code> |       |        |
+| <code>proprietary_data()</code>                   | *     |        |
+| <code>}</code>                                    |       |        |
+| <code>}</code>                                    |       |        |
+
+#### 9.8.8.1 Semantics of fields in proprietary\_command\_request\_data()
+
+**proprietary\_id:** This number is a 32-bit identifier that has been registered for a specific company. The contents of the command and the definition of how to process the command are proprietary. All definitions are beyond the scope of this Recommendation.
+
+**proprietary\_command:** This is a field, similar to the **opID** tag, which identifies individual proprietary commands for each proprietary id. The meaning of this field is not defined, but it must follow the basic rules for the protocol.
+
+**proprietary\_data():** This is a variable length field that contains the data for the specific proprietary command. The amount of data contained in the command can be determined from the overall length field for this command.
+
+The definition for this data is not specified, but it must follow the basic rules for the protocol.
+
+### 9.8.9 insert\_tier\_data request AS ==> IJ
+
+This is a supplemental usage request. When this request is processed, the **tier** value shall be copied into the associated ITU-T J.181 `splice_info_section` being created. One of the normal requests shall be placed earlier in the same `data()` buffer and this value will be added to the ITU-T J.181 section
+
+generated by that normal request. If this request is missing, the injector shall insert the value of 0xFFF into the **tier** field in the associated ITU-T J.181 splice\_info\_section being created.
+
+**Table 9-31 – insert\_tier\_data**
+
+| Syntax                                 | Bytes | Type   |
+|----------------------------------------|-------|--------|
+| insert_tier_data() {<br>tier_data<br>} | 2     | uimsbf |
+
+#### 9.8.9.1 Semantics of fields in insert\_tier\_data()
+
+**tier\_data**: A field with the most significant nibble set to 0x0 and containing in the lower 12-bits, a value with semantics as specified in [ITU-T J.181] for "**tier**".
+
+# 10 PAMS to the automation system communications
+
+The PAMS to the automation system communications are an optional, but normative section of this Recommendation. The PAMS is defined in logical terms, and no particular implementation is expected. The reader is reminded that PAMS is an acronym for "Provisioning and Alarm Management System".
+
+The messages defined within this section supply the required standard mechanisms for a bidirectional data communication system to support the following functional requirements:
+
+- System initialisation and service discovery
+- Data communications channel maintenance (sometimes called "heartbeat")
+- System restart from maintenance or redundancy change
+- Injector provisioning and de-provisioning in real time
+- Service addition and subtraction in real time
+- Failure reporting
+- Appropriate reaction to failures
+
+Additional functionality may be added, provided the core messages are compliant and function as described.
+
+## 10.1 System design philosophy
+
+The data communications between the PAMS and the AS is expected to be truly "peer to peer". This translates as, in outline form, that these communications must be:
+
+- Best effort communications: if a link is down and no other path is available, notify a human operator, but do not treat the link as de-provisioned
+- Notification of outages is not expected
+- Restarts are expected
+- Non-volatile storage of system and API parameters is expected
+- Data communications channel maintenance messages are optional
+- Full-time availability is not required for all aspects of the system (only injector signalling and redundancy handling)
+- A wide variety of system implementations are possible
+
+- The PAMS may not be a full-time participant in the overall system operation – it may divide functions between AMS (alarm management), which is expected to be full-time (and possibly not implemented in devices which have direct user interfaces) and P (provisioning), which may be available only on an "as needed" basis, when the operations staff need to change a given device's specific provisioning.
+
+Unidirectional systems are not expected to utilize the messages specified in this section, and could accomplish all of the same logical functions via manual initialization and coordination. The necessary functions are outlined above.
+
+Bidirectional system implementers are free to choose to support these messages or not; however, they must all be supported if any are. The user can be advised simply "PAMS support" or "no PAMS support" as regards a particular implementation.
+
+### **10.1.1 TCP/IP data communications**
+
+In a bidirectional system utilizing TCP/IP, the communication shall be purely peer-to-peer. Some system operators may desire that a heartbeat remain active between the two. This is provided as an optional extension.
+
+If either the automation system or the PAMS fail, there is no need to notify the other (or distribute alarms). When the failed system is again ready to function, it should issue either a config\_request message (automation system) or a provisioning\_request message (PAMS). If one system attempts to communicate with the other and there is no response, it shall continue functioning based on the last available configuration. Periodic retries shall be done until the other system eventually responds and normal communications is again established.
+
+### **10.1.2 Bidirectional serial data communications**
+
+As with TCP/IP, the communication is also peer-to-peer. Failures must be tolerated with alarm notification to the appropriate operational staff and periodic retries if the sender has need to communicate with the receiver (a failure notification to deliver, for example).
+
+## **10.2 PAMS functionality**
+
+As outlined above, the basic functionality is divided into the areas outlined in detail below. Each of these will be considered briefly in order:
+
+### **10.2.1 System initialization and service discovery**
+
+Initialization should happen (ideally) once when a system is first commissioned, and then never again. It is recognized that this is naïve, and messages are provided for restarting both an AS and the PAMS.
+
+It is handled by the config\_request, config\_response, provisioning\_request and the provisioning\_response messages. Please refer to clauses 10.4.1, 10.4.2, 10.5.1 and 10.5.2.
+
+### **10.2.2 Data communications channel maintenance**
+
+Capabilities are provided for PAMS to AS "link alive" messages if desired by the end user.
+
+This is handled by the AS\_alive request and the AS\_alive response messages. Please refer to clauses 10.7.1 and 10.7.2.
+
+### **10.2.3 System restart from maintenance or redundancy change**
+
+Messages are provided for restarting both an AS and the PAMS.
+
+This is handled by the config\_request, config\_response, provisioning\_request and the provisioning\_response messages. Please refer to clauses 10.4.1, 10.4.2, 10.5.1 and 10.5.2.
+
+### **10.2.4 Injector provisioning and de-provisioning in real time**
+
+The specifics of provisioning and de-provisioning of injectors is dealt with in clause 11 and are not further specified, except from a logical viewpoint. Notification is handled via the provisioning\_request and the provisioning\_response messages. Please refer to clauses 10.5.1 and 10.5.2.
+
+### **10.2.5 Service addition and subtraction in real time**
+
+Handled by the provisioning\_request and the provisioning\_response messages. Please refer to clauses 10.5.1 and 10.5.2.
+
+### **10.2.6 Failure reporting**
+
+Failure reporting is defined in this clause and shall be present whenever the system is operational. A number of implementation architectures will meet this requirement.
+
+This is handled by the fault\_request and the fault\_response messages. Please refer to clauses 10.6.1 and 10.6.2.
+
+### **10.2.7 Appropriate reaction to failures**
+
+Injector replacement notification and action is defined in this clause and shall be present whenever the system is operational. A number of implementation architectures will meet this requirement.
+
+Notification is via the provisioning\_request and the provisioning\_response messages. Please refer to clauses 10.5.1 and 10.5.2.
+
+### **10.2.8 System initialization**
+
+System initialization is an infrequent event. This API defines messages to be utilized in bidirectional systems to permit system to system notification of events and changes in status. Both the AS and the PAMS shall expect notification messages from the other and process them in manners which do not disrupt DPI or other services.
+
+The definition of the PID or PIDs used for DPI service and their method of creation is beyond the scope of this Recommendation.
+
+## **10.3 Service continuity**
+
+Initialization (or re-initialization) of the communications between the AS and the PAMS shall not cause interruption of any of the audio, video or DPI services currently being processed by either the AS or the DCS. Initialization can be safely conducted at any point in time. This includes changes to injector services or injectors themselves. These events may be expected to occur at random intervals.
+
+## **10.4 System initialization messages**
+
+The manner in which the initial IP address for the PAMS is conveyed to the automation system is beyond the scope of this Recommendation.
+
+In a bidirectional system utilizing TCP/IP, the initial communication begins with the PAMS listening on predefined socket 5167 and the automation system opening an API connection to the PAMS via that socket. The automation system sends a config\_request to the PAMS. The automation system then listens for the response from the PAMS and closes the API connection. For all further PAMS-to-the automation system communication, the PAMS will use the IP address and port number supplied in the Config\_Request message. This message may also be used to notify the PAMS of the automation system redundancy switching.
+
+### 10.4.1 config\_request message AS ==> PAMS
+
+When the PAMS receives config\_request message, it will store the automation system configuration info for further use, and immediately respond with a config\_response message.
+
+This message shall be sent at system initialization, following AS downtime for whatever reason, and upon AS redundancy switch requiring the PAMS to connect to a new IP address.
+
+**Table 10-1 – config\_request\_data**
+
+| Syntax                         | Bytes | Type   |
+|--------------------------------|-------|--------|
+| config_request_data(){         |       |        |
+| AS_IP_address                  | 4     | uimsbf |
+| AS_socket_number               | 2     | uimsbf |
+| activeflag                     | 1     | uimsbf |
+| protocol_version               | 1     | uimsbf |
+| last_AS_index                  | 1     | uimsbf |
+| last_injectorcount             | 2     | uimsbf |
+| permanent_connection_requested | 1     | uimsbf |
+| }                              |       |        |
+
+#### 10.4.1.1 Semantics of fields in config\_request\_data()
+
+**AS\_IP\_address:** This is the IP address of the automation system. In a bidirectional serial communications system architecture, it shall be zero.
+
+**AS\_socket\_number:** This is the TCP port of the automation system, waiting for incoming communication from the PAMS. In a bidirectional serial communications system architecture, it shall be zero.
+
+**activeflag:** Boolean flag indicating if this AS instance acts as a primary or a backup. Zero indicates the AS is a backup, non-zero indicates the AS is a primary.
+
+**protocol\_version:** An 8-bit unsigned integer which indicates the version number of the protocol and which shall be 0x00.
+
+**last\_AS\_index:** Value of the **AS\_index** provided by the PAMS during a previous system initialization. If used, it ranges from 1 to 255. If not used, or this is the first system initialization, it is zero.
+
+**last\_injectorcount:** Value of the **injectorcount** last provided by the PAMS. Zero during the first system initialization.
+
+**permanent\_connection\_requested:** Non-zero indicates that maintaining a permanent TCP/IP link has been provisioned on the AS side. The PAMS will not close the TCP/IP socket after sending the provisioning\_request message and will supply heartbeat messages. A backup AS may request a permanent connection.
+
+#### 10.4.1.2 Detailed discussion of message syntax and semantics
+
+Under normal circumstances, the PAMS will communicate only with the automation system IP address with **activeflag** set to TRUE. The one exception is if the provisioning\_request message (see clause 10.5.1 for details) from the backup requests a permanent connection be maintained.
+
+When a backup AS instance takes over as primary, it shall send a config\_request message to the PAMS as a method of notifying the PAMS that a new IP address and socket must be connected to. In this case, the AS supplies the value for **AS\_index** initially furnished at system start-up.
+
+### 10.4.2 config\_response message PAMS ==> AS
+
+The config\_response message conveys back an index value later used to populate the **AS\_index** field in the single\_operation\_message() and multiple\_operation\_message() structures (clauses 8.2.2 and 8.2.3) and indicates that the config\_request message was received. This message can also contain a result code (see Table 14-1), if appropriate.
+
+For systems using TCP/IP data communications, once the PAMS sends this message, it will immediately close the socket and reopen TCP/IP communications using the **AS\_IP\_address** and **AS\_socket\_number** values from the config\_request message. It will then send a provisioning\_request message (see clause 10.5.1) to the AS.
+
+**Table 10-2 – config\_response\_data**
+
+| Syntax                         | Bytes | Type   |
+|--------------------------------|-------|--------|
+| config_response_data(){        |       |        |
+| AS_index                       | 1     | uimsbf |
+| permanent_connection_requested | 1     | uimsbf |
+| }                              |       |        |
+
+#### 10.4.2.1 Semantics of fields in config\_response\_data()
+
+**AS\_index**: This is the index provided by the PAMS, ranging from 0 to 255. See clause 8.2.1 for a complete discussion regarding usage of this value.
+
+When responding to a redundancy switch within a given AS, this shall be the same value contained in the **last\_AS\_index** in the config\_request message.
+
+**permanent\_connection\_requested**: Non-zero indicates that maintaining a permanent TCP/IP link has been provisioned on the PAMS side. If this is requested, the PAMS will not close the TCP/IP socket after sending the provisioning\_request message and will supply AS\_alive messages.
+
+## 10.5 Injector service notification
+
+The PAMS shall notify the AS of all active injectors at the time of system initialization or re-initialization and shall notify the AS of any new injectors as they are provisioned. In a similar manner, the PAMS shall notify the AS of any injectors which are de-provisioned.
+
+A provisioning\_request message is also sent by the PAMS upon re-initialization following either downtime for maintenance, non-redundant failure, or redundant switchover. If AS\_alive messages had been requested, they would then be resumed following the receipt of a provisioning\_response message.
+
+### 10.5.1 provisioning\_request message PAMS ==> AS
+
+PAMS will notify the automation system of all injectors ready for use in DPI service via the following structure. In some system architectures, the same IP address and socket may be shared by different services with the injector.
+
+**Table 10-3 – provisioning\_request\_data**
+
+| Syntax                                 | Bytes | Type   |
+|----------------------------------------|-------|--------|
+| provisioning_request_data(){           |       |        |
+| service_count                          | 1     | uimsbf |
+| for (i=0; i<service_count; i++) {      |       |        |
+| injector_IP_address                    | 4     | uimsbf |
+| injector_socket_number                 | 2     | uimsbf |
+| service_name                           | 32    | bslbf  |
+| number_of_DPI_PIDs                     | 1     | uimsbf |
+| for (i=0; i<number_of_DPI_PIDs; i++) { |       |        |
+| DPI_PID_index                          | 2     | uimsbf |
+| shared_PID                             | 1     | uimsbf |
+| cue_stream_type                        | 1     | uimsbf |
+| }                                      |       |        |
+| component_mode                         | 1     | uimsbf |
+| if (component_mode != 0){              |       |        |
+| injector_component_list()              |       |        |
+| }                                      |       |        |
+| }                                      |       |        |
+
+#### 10.5.1.1 Semantics of fields in provisioning\_request\_data()
+
+**service\_count:** This specifies the number of services defined within the following loop. Each iteration of the loop defines basic data for a given injector instance.
+
+**injector\_IP\_address:** This is a standard 32-bit IP address. This is the IP address of the injector. In systems not using TCP/IP communications, the value of this field shall be zero.
+
+**injector\_socket\_number:** This is a standard 16-bit socket number. In systems not using TCP/IP communications, the value of this field shall be zero.
+
+**service\_name:** A case sensitive string value, terminated by a 0x00 byte giving the service name. This value must be manually provisioned by both the AS and the PAMS and must match. It is used to unambiguously identify the service. There may be duplicate service\_names only for hot backups.
+
+**number\_of\_DPI\_PIDs:** Count of the number of DPI PIDs provisioned. This number shall range from 1 to the limit specified in [ITU-T J.181].
+
+**DPI\_PID\_index:** The PID index for each specific DPI service. The value is not an actual PID number, rather the index by which the AS may request the specific service identified by **cue\_stream\_type**. This value populates the **DPI\_PID\_index** variable in both the **single\_operation\_message()** and **multiple\_operation\_message()** structures (see clauses 8.2.2 and 8.2.3). It is normally assigned a unique value unless a shared PID situation is signalled by a non-zero value in **shared\_PID**. The rules for usage of **DPI\_PID\_index** are defined in clause 8.2.1.
+
+**shared\_PID:** A zero value indicates that the corresponding value of **DPI\_PID\_index** is unique. A value of one indicates that the corresponding value of **DPI\_PID\_index** is intentionally duplicated (typically the same video with different language audio tracks) and that the AS should only communicate with one instance of **DPI\_PID\_index**. This flag shall be set to one for all instances of the corresponding **DPI\_PID\_index**.
+
+**cue\_stream\_type**: It identifies the type of cue stream. The values are taken from Table 8-3 of [ITU-T J.181].
+
+**component\_mode**: This is the length of the injector\_services\_list (). A zero value indicates no services\_list is present.
+
+**injector\_component\_list ()**: See clause 10.8.1.
+
+#### 10.5.1.2 Detailed discussion of message syntax and semantics
+
+The PAMS will send this message whenever the configuration for an injector changes. This could be during provisioning, removal or reallocation after a failure. This approach allows the automation system to verify that its internal data structure is in sync with the PAMS injector configuration. If no injectors have been provisioned, then a zero InjectorCount message is sent. This confirms to the automation system that the PAMS is active, even if no injectors have been provisioned for DPI service.
+
+The AS is expected to check the consistency of the values assigned to **DPI\_PID\_index** and to send the provisioning\_response message with a **result** code of "Inconsistent value of DPI PID index found" (see Table 14-1). If an expected common value of **DPI\_PID\_index** is not found, then the AS should send the provisioning\_response message with a **result** code of "Shared value of DPI PID index not found" (see Table 14-1). If a common value of **DPI\_PID\_index** is found across physical injectors or in a situation where the AS is not expecting a shared PID, then the AS shall send the provisioning\_response message with a **result** code of "Illegal shared value of DPI PID index found" (see Table 14-1). Both the PAMS and the AS should produce alarms immediately upon sensing this condition to permit the operations staff to resolve the discontinuity.
+
+If the user changes an injector's **service\_name** value, then this message is sent again to the automation system.
+
+PAMS will send this message to both a primary and a backup automation system IP address if such are defined.
+
+The AS, the PAMS and the injectors shall all comply with the requirements of service continuity outlined in clause 10.3 when processing this message.
+
+### 10.5.2 provisioning\_response message AS ==> PAMS
+
+The provisioning\_response message contains no data and indicates that the provisioning\_request message was received. This message may return a result code (see clause 14) if appropriate. The AS is expected to return specific result codes in certain circumstances. Please refer to the discussion of **DPI\_PID\_index** uniqueness in clause 8.2.1.
+
+**Table 10-4 – provisioning\_response\_data**
+
+| Syntax                             | Bytes | Type |
+|------------------------------------|-------|------|
+| provisioning_response_data(){<br>} |       |      |
+
+## 10.6 Failure notification messages (device or communications)
+
+The messages in this section shall be utilized by either the AS or the PAMS to notify the other of failures in situations where the other system **must take action** in response to the notification. Such action may take the form of an automatic response (for example a change of injectors requiring a switch of IP addresses and an initialization of communications with the new injector) or notification of the system operator (for example, an apparent communications failure). The action taken in response to receipt of these messages may be operationally constrained; however, the minimal reaction of the recipient system shall be alarm notification to the system operator.
+
+Notification of the AS of an injector replacement shall utilize the provisioning\_request message defined in clause 10.5.1.
+
+Since the AS can sense an apparent injector failure, a message is provided for this specific notification. The PAMS must be ready to accept injector failure notification from the AS at any point, before, during or after it has processed any injector failures that it may have detected on its own. Operational procedures for handling such a failure will be system specific.
+
+### 10.6.1 fault\_request message AS ==> PAMS
+
+This message permits the AS to notify the PAMS of a possible failure of either an injector or the data communications link to that injector. Resultant action taken by the PAMS shall be configurable by the operations staff of the DCS site. When automatic replacement is desired by that staff, this message shall result in an automatic replacement of an injector. The minimum compliant response shall be the generation of an operator alarm.
+
+As a result of receipt of this message, the PAMS may (if configured to do so) automatically trigger a redundancy replacement of an injector (which shall result in it sending a provisioning\_request message after the switch). It may also notify the operator or request operator guidance. The specifics of the precise reaction to this message must be left to operational provisioning of the PAMS and the DCS.
+
+After sending a fault\_request message and receiving a fault\_response in return, the AS may logically expect to receive a provisioning\_request message at some point in the future to notify the AS of the injector change. In the meantime, until such a notification is given, the AS shall continue to periodically attempt to communicate with the injector, since the link failure may be only visible to the AS and operations personnel may restore the link based on the fault\_request notification. In such cases, the AS shall re-establish the communications and continue operating as if a failure had never been detected.
+
+**Table 10-5 – fault\_request\_data**
+
+| Syntax                 | Bytes | Type   |
+|------------------------|-------|--------|
+| fault_request_data(){  |       |        |
+| injector_IP_address    | 4     | uimsbf |
+| injector_socket_number | 2     | uimsbf |
+| injector_service_name  | 32    | bslbf  |
+| DPI_PID_index          | 2     | uimsbf |
+| }                      |       |        |
+
+#### 10.6.1.1 Semantics of fields in fault\_request\_data()
+
+**injector\_IP\_address:** This is a standard 32-bit IP address. It is zero if TCP/IP communications are not being used.
+
+**injector\_socket\_number:** This is a standard 16-bit socket number. It is zero if TCP/IP communications are not being used.
+
+**injector\_service\_name:** This is a string value, terminated by a 0x00 byte giving the injector service name. This value must match the name sent by the PAMS in the defining provisioning\_request message. It is used to unambiguously identify the service.
+
+**DPI\_PID\_index:** The PID index for the specific DPI service which appears to have failed. This field may be zero if the injector can be unambiguously identified by the other three fields in this message. The rules for usage of this field are defined in clause 8.2.1.
+
+### 10.6.2 fault\_response message PAMS ==> AS
+
+The fault\_response message contains no data and indicates that the fault request message was received. This message may return a result code (see Table 14-1) if appropriate, including an indication of "no fault found".
+
+**Table 10-6 – fault\_response\_data**
+
+| Syntax                      | Bytes | Type |
+|-----------------------------|-------|------|
+| fault_response_data(){<br>} |       |      |
+
+## 10.7 PAMS to AS permanent "link alive" messages
+
+Use of permanent "link alive" messages (also called a "heartbeat") between the PAMS and the AS is optional in usage, depending upon operational provisioning. All PAMS and AS which support messages within clause 9.8.9 of this document are expected to support this permanent "link alive" message functionality. Either system can request that this service is initiated and the other shall cooperate in maintaining it. Both TCP/IP and bidirectional serial systems shall support "link alive" messages.
+
+If loss of the link is detected by either the AS or the PAMS, it shall result in immediate operator notification.
+
+### 10.7.1 AS\_alive\_request PAMS ==> AS
+
+This basic request serves to ensure that the PAMS to AS communications path remains open and reliable. If there has been no activity on the connection in the preceding 60 seconds, then an **AS\_alive\_request** message shall be sent.
+
+**Table 10-7 – AS\_alive\_request\_data**
+
+| Syntax                        | Bytes | Type |
+|-------------------------------|-------|------|
+| AS_alive_request_data(){<br>} |       |      |
+
+### 10.7.2 AS\_alive\_response AS ==> PAMS
+
+This basic response serves to ensure that the AS to PAMS communications path remains open and reliable.
+
+**Table 10-8 – AS\_alive\_response\_data**
+
+| Syntax                         | Bytes | Type |
+|--------------------------------|-------|------|
+| AS_alive_response_data(){<br>} |       |      |
+
+## 10.8 PAMS to AS common elements
+
+### 10.8.1 injector\_component\_list() definition
+
+This structure defines the list of component services carried by a given injector instance. This is utilized only if component mode splicing is supported.
+
+**Table 10-9 – injector\_component\_list()**
+
+| Syntax                                                | Bytes | Type   |
+|-------------------------------------------------------|-------|--------|
+| injector_component_list {                             |       |        |
+| video_component_tag                                   | 1     | uimsbf |
+| number_of_audio_component_tags                        | 1     | uimsbf |
+| for (i=0; i<number_of_audio_component_tags;<br>i++) { |       |        |
+| audio_component_tag                                   | 1     | uimsbf |
+| }                                                     |       |        |
+| number_of_data_component_tags                         | 1     | uimsbf |
+| for (i=0; i<number_of_data_component_tags;<br>i++) {  |       |        |
+| data_component_tag                                    | 1     | uimsbf |
+| }                                                     |       |        |
+| }                                                     |       |        |
+
+#### 10.8.1.1 Semantic definition of fields in injector\_component\_list()
+
+**video\_component\_tag:** Component\_tag value of the video stream.
+
+**number\_of\_DPI\_PIDs:** count of the number of DPI PIDs provisioned.
+
+**number\_of\_audio\_component\_tags:** count of the audio component\_tags (hence the index of the component\_tag list).
+
+**audio\_component\_tag:** Component\_tag value of each specific audio stream.
+
+**number\_of\_data\_component\_tags:** count of the data component\_tags.
+
+**data\_component\_tag:** Component\_tag value of each specific data service.
+
+# 11 PAMS to injector communications (informative)
+
+The communications specifics between the injector and the PAMS can be expected to be proprietary and out of the scope of this Recommendation. This document will specify logical operations which are necessary to ensure this API functions properly as a system.
+
+## 11.1 The PAMS implementation
+
+It must be noted that the PAMS is a logical function which may be realized in real implementations in a variety of manners. This API does not dictate any particular implementation, rather it specifies the logical functions that the PAMS must realize. The only mandated function is that there be a method of alerting the system operator of injector or communications failures.
+
+This API does expect that the PAMS will store system configuration information in some non-volatile storage media to ensure continuity in cases of hardware failure which require the replacement of a/some component(s) of the PAMS hardware.
+
+## 11.2 Injector provisioning
+
+Injector provisioning will be done in response to operator input into the PAMS. Injector provisioning includes notifying the injector of the PID to be used for DPI splice\_info\_sections and possibly setting other injector parameters. Provisioning will also define the maximum number of socket connections that the injector must make available for multiple automation systems. Response by the injector to this provisioning includes placing the ITU-T J.181 registration descriptor in the PMT for that service.
+
+This API provides capabilities for multiple services per injector, as well as multiple AS. The **AS\_index** and **DPI\_PID\_index** fields in the various messages are utilized to ensure that in all cases the AS, the injector and the service on that injector can be uniquely identified. Implementations which do not support one or more of these aspects simply constrain the values of those fields to zero.
+
+## 11.3 PAMS structure
+
+The provisioning of injectors is dealt with in clause 11.2 and is not further specified, except from a logical viewpoint. The alarm management and the overall initialization aspects are within scope, and they are defined in this clause. Initialization should happen (ideally) once when a system is first commissioned, and then never again. The initialization aspect of the PAMS might then go offline. The alarm management aspect remains vigilant, however. A number of implementation architectures will meet this requirement. For more information see clause 11.1. There are requirements for service continuity specified in clause 10.3.
+
+## 11.4 Support of multiple DPI PIDs
+
+The attention of implementers must be drawn to the question of the DCS's support of multiple DPI PIDs. This refers to (1) multiple services per injector, (2) multiple PIDs per service, (3) multiple injector instances per data communications connection (i.e., per IP address or serial link), (4) a combination of these, or (5) multiple automation systems connecting to a single DCS. Please consult clause 8.2.1 for a comprehensive discussion of this topic.
+
+This API provides a mechanism for unambiguous request addressing in a system supporting multiple injector instances, namely the field named **DPI\_PID\_index** found in both **single\_operation\_message()** and **multiple\_operation\_message()**. The value for each injector instance is communicated by the PAMS to the automation system via the field named **DPI\_PID\_index**.
+
+Assuming that the implementers wish to support multiple services and that these are provisioned by the operational staff, the values returned in **DPI\_PID\_index** will be non-zero and provide the automation system an unambiguous method of identifying the desired service on a particular data communications link. Please see clause 8.2.1 for additional background information.
+
+# 12 Common elements
+
+The following are the common syntactic elements used throughout this API. They are listed here for ease of reference.
+
+## 12.1 Values of **splice\_event\_id** used in this interface
+
+Splicers use the **splice\_event\_id** to determine when multiple messages refer to the same event (insertion opportunity).
+
+AS implementers should be aware of the **splice\_event\_id** uniqueness discussion in Section 5.3 of [b-ANSI/SCTE 67].
+
+## 12.2 Values of **unique\_program\_id** used in this interface
+
+The usage of particular values for the **unique\_program\_id** field by servers and splicers is outside the scope of this Recommendation. Once set by the AS, the value of the field is relied upon for operations as defined by the syntax.
+
+## 12.3 Minimum pre-roll time supported by this interface
+
+In compliance with the requirements of [ITU-T J.181], and in keeping with the advice of [b-ANSI/SCTE 67], the minimum non-zero value of pre-roll time shall be 4000 milliseconds for a **splice\_request**. A zero value may be sent if **splice\_insert\_type** is *spliceStart\_immediate* or *spliceEnd\_immediate*. If the automation system is somehow notified of an event with less time than
+
+the minimum, it might count itself down to the trigger time and request a *spliceStart\_immediate* operation.
+
+*SpliceEnd\_normal* shall use a pre-roll, even though it has been common practice in the industry for a return command to be sent with zero pre-roll. *SpliceEnd\_immediate* sets the immediate bit which indicates an early return from a splice. It effectively aborts any content insertion currently in progress.
+
+NOTE – There is an important distinction between a pre-roll of zero and a splice return with the immediate bit set. A *spliceEnd\_normal* indicates that the content insertion should have ended approximately at the time indicated, with or without a pre-roll value. Common industry practice has been to ignore a normal return message in favour of finishing the playout of the content. Any receive device may choose to use a return message as a sanity check, and if it determines that the content will excessively exceed the time indicated, it may choose to return to the network early and flag an error.
+
+## 12.4 time() definition
+
+This structure serves to carry the current time of day sample of the sender.
+
+**Table 12-1 – time()**
+
+| Syntax       | Bytes | Type   |
+|--------------|-------|--------|
+| time() {     |       |        |
+| seconds      | 4     | uimsbf |
+| microseconds | 4     | uimsbf |
+| }            |       |        |
+
+### 12.4.1 Semantic definition of fields in time()
+
+**seconds:** These are the elapsed seconds since 12:00 AM UTC January 6, 1980 with the count of intervening leap seconds included.
+
+**microseconds:** This is the offset in microseconds of the **seconds** field.
+
+## 12.5 timestamp() definition
+
+This structure serves to carry both current and future time samples, as well as contact closure triggers.
+
+**Table 12-2 – timestamp()**
+
+| Syntax                 | Bytes | Type   |
+|------------------------|-------|--------|
+| timestamp(){           |       |        |
+| time_type              | 1     | uimsbf |
+| if( time_type == 1 ) { |       |        |
+| UTC_seconds            | 4     | uimsbf |
+| UTC_microseconds       | 2     | uimsbf |
+| }                      |       |        |
+| if( time_type == 2 ) { |       |        |
+| hours                  | 1     | uimsbf |
+| minutes                | 1     | uimsbf |
+| seconds                | 1     | uimsbf |
+| frames                 | 1     | uimsbf |
+| }                      |       |        |
+| if( time_type == 3 ) { |       |        |
+| GPI_number             | 1     | uimsbf |
+| GPI_edge               | 1     | uimsbf |
+| }                      |       |        |
+| }                      |       |        |
+
+### 12.5.1 Semantic definition of fields in timestamp()
+
+**time\_type:** If the value is set to 0, then there is no time required and the remainder of the structure is empty. A value of 1 indicates that the time field has been set up for UTC time for triggering a DPI splice\_info\_section. A value of 2 indicates that the time field has been set up for SMPTE VITC time code [b-SMPTE EG 40] for triggering a DPI splice\_info\_section. A value of 3 indicates that a GPI input is being used to trigger a DPI splice\_info\_section.
+
+NOTE – Non-zero values of **time\_type** that are not currently defined are reserved for future standardization. Any message received with a **time\_type** it does not understand should be ignored and an error code of "time type unsupported" returned to the requester. This error should not occur under normal circumstances, since the **protocol\_version** will need to be increased to support new definitions of time.
+
+**UTC\_seconds:** These are the elapsed seconds since 12:00 AM UTC January 6, 1980 UTC with the count of intervening leap seconds included.
+
+**UTC\_microseconds:** This is the offset in microseconds of the **UTC\_seconds** field.
+
+**hours:** This field encodes the hour of the day in 24-hour time. Values range from 0 to 23.
+
+**minutes:** This field encodes the minute of the hour. Values range from 0 to 59.
+
+**seconds:** This field encodes the seconds of the minute. Values range from 0 to 59.
+
+**frames:** This field encodes the frame within the current second. The range of values changes based upon whether the system is 30 Hz or 25 Hz based video and whether or not the frame rate is actually
+
+divided by 1.001. Typical values are 0 to 29 for 30 or 30/1.001 Hz systems, and 0 to 24 for 25 Hz systems<sup>3</sup>.
+
+**GPI\_number:** This field encodes a number from 0 to 255 and indicates the GPI to use for triggering the insertion of the DPI splice\_info\_section. The actual number of GPIs available, the GPI numbering and the edge used for triggering are details of implementation. The automation system should know these details in order to choose a proper value for this field. If the physical GPI does not exist, the injector should discard the request and raise an alarm to the operator.
+
+**GPI\_edge:** This field encodes the edge to use to trigger message processing. A value of 0 indicates a transition from open to closed. A value of 1 indicates a transition from closed to open.
+
+# 13 System architecture and provisioning (informative)
+
+## 13.1 One-way protocol – automation system to injector
+
+### 13.1.1 System architecture summary
+
+This architecture assumes that an automation system (AS) only connects with injectors over a one-way communication link. Figure 13-1 below shows the injector as a black box within the encoder. The protocol can use a link layer that is embedded in video (e.g., SDI VANC area) or a serial communications protocol (e.g., RS-232) directly connected to the encoder. The normal assumption for this type of system is that there is a single ITU-T J.181 PID (or DPI PID for short) generated for each encoder. This system is not limited to a single DPI PID however, but extra provisioning will be required to support multiple DPI PID streams.
+
+This system shows a simplified version of how SDI VANC embedding works. The automation system would maintain N serial outputs (4 in this example), one for each primary encoder. Each of the serial data channels would be directed to an embedder for the specific video channel that the DPI data is associated to. The SDI stream is then fed through a video switcher for redundancy. The video stream may be directed to either the primary encoder or one of the backup encoders as required. Since the DPI data stream is embedded within the video, the correct DPI commands for the video are always available to whichever device receives the video. The exact method of embedding DPI commands into the VANC area is standardized by [SMPTE ST 2010].
+
+---
+
+<sup>3</sup> One should be aware that SMPTE VITC time code allows dropped or repeated frames. If the automation system should give a time stamp that is lost because the source dropped that frame, then the message should be generated on the first frame following the dropped frame. Automation systems should avoid using time stamps near discontinuities in the time code. For example, if time code 23:59:59:29 was given, but the source dropped this frame, then the message would never be generated because it would never see a time code higher than the specified time code.
+
+![Figure 13-1: One-way protocol embedded in video with integrated injector. The diagram shows an AS (Automation System) connected to a 4x SDI embedder. The output of the embedder is connected to a Video switch. The Video switch is connected to six Enc/Injector blocks. These blocks are connected to a MUX. A PAMS (Packet Management System) is connected to the Video switch, the Enc/Injector blocks, and the MUX via dashed lines. The label J.287(14)_F13-1 is at the bottom right.](87c64bd7d33fca8b9b29228c80ddf175_img.jpg)
+
+Figure 13-1: One-way protocol embedded in video with integrated injector. The diagram shows an AS (Automation System) connected to a 4x SDI embedder. The output of the embedder is connected to a Video switch. The Video switch is connected to six Enc/Injector blocks. These blocks are connected to a MUX. A PAMS (Packet Management System) is connected to the Video switch, the Enc/Injector blocks, and the MUX via dashed lines. The label J.287(14)\_F13-1 is at the bottom right.
+
+**Figure 13-1 – One-way protocol embedded in video with integrated injector**
+
+Figure 13-2 shows the injector as a separate chassis. Each physical box contains one or more injector instances, one for each DPI PID that is to be generated by that injector. The automation system maintains one serial channel for each physical device, and can use the **DPI\_PID\_index** field to direct the traffic to the injector instance associated to that specific video stream. This diagram also shows multiple automation systems connected to each injector. The communication link of each automation system is multiplexed in a single physical input on the injector. This type of system will require the **AS\_index** field to distinguish traffic from each AS.
+
+This injector is assumed to output transport packets suitable for multiplexing into a standard transport stream. This diagram is still in a logical view, since there are many physical architectures that could work. Examples are separate boxes (as shown), the injector in the multiplexer, or all encoders, injectors, and the multiplexer in one chassis.
+
+![Figure 13-2: One-way protocol with multiple AS to external injector. The diagram shows two AS (Automation System) blocks connected to a central Injector block. The Injector block is connected to a MUX. The MUX is connected to six Encoder blocks. The Encoder blocks are connected to a PAMS (Packet Management System) via dashed lines. The label J.287(14)_F13-2 is at the bottom right.](1f1614411edea7edfc86c839a608e1fc_img.jpg)
+
+Figure 13-2: One-way protocol with multiple AS to external injector. The diagram shows two AS (Automation System) blocks connected to a central Injector block. The Injector block is connected to a MUX. The MUX is connected to six Encoder blocks. The Encoder blocks are connected to a PAMS (Packet Management System) via dashed lines. The label J.287(14)\_F13-2 is at the bottom right.
+
+**Figure 13-2 – One-way protocol with multiple AS to external injector**
+
+### 13.1.2 Automation system provisioning requirements
+
+The following system description gives the essential information required in both the AS and the injector to allow an automation system to communicate with a specific injector for a single service. This includes support for multiple injectors for the purpose of redundancy. It is expected that all of the information must be provided separately for every service in the system. In a number of cases, the provisioning of the AS and the injectors is the same as that described for the "Two-way protocol – Automation system to injector only" described in clause 13.2.
+
+#### 13.1.2.1 Service definition and DPI\_PID\_index
+
+For each physical connection there is a list of one or more MPEG services that may have a DPI PID stream produced from commands carried on that connection. Each MPEG service may have zero to eight DPI PIDs assigned to it. This assumes that a service with no DPI PIDs does not need to be provisioned to an injector. The automation system and injector must both have a common agreement on what content is contained on every service.
+
+The commands used to create a specific DPI message are the same for the one and two way protocols. If there is more than one DPI PID in the encoder, then a **DPI\_PID\_index** must be provisioned in both the automation system and the injector. In order to simplify the network, the **DPI\_PID\_index** should be unique in the entire DCS, if it is used at all. If there is at most one DPI PID generated per encoder, then it is acceptable to use a value of zero for all **DPI\_PID\_index** which indicate that this field is not required for proper operation.
+
+The reasons for using **DPI\_PID\_index**, and the methods to provision the value in both the AS and injector are the same as in the two-way protocol and will not be repeated here. This includes both component mode and non-component mode support (see clause 13.2.3).
+
+#### 13.1.2.2 Automation index (AS\_index field)
+
+When more than one automation system communicates to a single DPI PID on a single physical connection, each automation system should be provided with a unique **AS\_index** value. If there is only one automation system supplying information for a DPI component, the **AS\_index** can be set to zero, indicating that this parameter is not required for proper operation. Since **DPI\_PID\_index** is coordinated for the entire DCS, including multiple automation systems, the **AS\_index** is not required as long as there is a one-for-one relationship.
+
+If there are redundant automation systems and the **AS\_index** field is non-zero, then the same **AS\_index** should be assigned to both the primary and backup systems. It is the responsibility of the automation systems to coordinate between themselves which one is active at any one time. Only one of these redundant automation systems should communicate to the injector at any one time.
+
+The injector can use the **AS\_index** to distinguish between messages coming from different devices, and can provide some self-checks to ensure that control for a specific MPEG service is coming from the expected automation system. It is also used to ensure that the different automation system does not assign duplicate Event Ids, for example. Any cancel from one automation system will not cancel commands from the other automation system.
+
+#### 13.1.2.3 Time
+
+In a one-way system, the link layer may be of a lower bandwidth and would benefit from more time to process the commands. Using the delayed processing type will help provide more time for commands. In order to use the timestamp() feature of the messages, the time in both the injector and the automation system need to be coordinated within a few milliseconds of each other. The exact method of synchronization is a system design issue. It is expected that the alive request message will be used for synchronization.
+
+Other methods may be used if available, such as:
+
+- NTP
+- GPS
+- SMPTE time codes.
+
+If the system is designed to work in immediate processing mode, time synchronization is not necessary.
+
+If the system utilizes a proxy device in a delayed unidirectional mode, upon arrival of the triggering event, the proxy device shall remove the `timestamp()` structure as presented by the AS and replace it with a single byte of 0, as per clause 12.5.1, change the `messageSize` value to reflect that change, and move the remainder of the bytes in the message forward to fill in as appropriate. The message shall be placed into the VANC space of the next frame of video for delivery to the injector.
+
+#### 13.1.2.4 Encryption in the automation system
+
+Encryption is an optional component in ITU-T J.181 systems. If used, the encryption commands are used the same way as described for the two-way system in clause 13.2.7.
+
+#### 13.1.2.5 DTMF descriptors
+
+If the automation system wishes to control the output of analogue cue tones coincident with the digital cue tones, then it must be provisioned with the DTMF tone sequence and the pre-roll timing. If used, the DTMF descriptor information is provisioned and used the same way as described for the two-way system in clause 13.2.8.
+
+### 13.1.3 Automation system $\Leftrightarrow$ Injector messages
+
+#### 13.1.3.1 Supported messages
+
+The following table gives the various commands that can be used between the automation system and the injector in a one-way system. Note that the commands are identical in the AS to injector direction, and all responses are not used. For more detailed descriptions, one can refer to the information given for the two-way system.
+
+**Table 13-1 – Supported protocol messages**
+
+| Command                          | Type   | Direction                 | Description                                                                                                                                                                                                                                           |
+|----------------------------------|--------|---------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| <code>splice_request</code>      | Either | AS $\Rightarrow$ Injector | Sent any time a splice is to be signalled                                                                                                                                                                                                             |
+| <code>alive_request</code>       | Single | AS $\Rightarrow$ Injector | Sent periodically to ensure that the connection is active to the automation system.<br>May include the current time so that the AS and injector can maintain a synchronized timebase.                                                                 |
+| <code>time_signal_request</code> | Either | AS $\Rightarrow$ Injector | Generates an ITU-T J.181 time signal message. While either type may be used, time signal will normally have a descriptor associated with it, making the multiple command type the normal type.                                                        |
+| <code>splice_null request</code> | Single | AS $\Rightarrow$ Injector | Generates an ITU-T J.181 nullmessage. If the Nullmessage is used to generate a heartbeat message, the single command type is likely to be used.<br>If the Nullmessage is used to convey a private descriptor, the multiple command type must be used. |
+
+**Table 13-1 – Supported protocol messages**
+
+| Command                     | Type   | Direction                 | Description                                                                                                                                                                                  |
+|-----------------------------|--------|---------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| proprietary_command request | Either | AS $\Rightarrow$ Injector | A generic basic command. This is used for future support of standard commands or proprietary extension. Like other basic commands, one may attach advanced commands like the inject section. |
+
+**Table 13-2 – Unsupported protocol messages**
+
+| Command                  | Type   | Direction                 | Description                                                                                                                  |
+|--------------------------|--------|---------------------------|------------------------------------------------------------------------------------------------------------------------------|
+| init_request             | Single | AS $\Rightarrow$ Injector | Information contained is not useful in a one-way system. The alive_request serves as the initialization of a one-way system. |
+| init_response            | Single | AS $\Leftarrow$ Injector  | No return path.                                                                                                              |
+| inject_response          | Single | AS $\Leftarrow$ Injector  | No return path.                                                                                                              |
+| inject_complete_response | Single | AS $\Leftarrow$ Injector  | No return path.                                                                                                              |
+| alive_response           | Single | AS $\Leftarrow$ Injector  | No return path.                                                                                                              |
+
+#### 13.1.3.2 Optional commands
+
+Some features are deemed optional in an automation system:
+
+- Encryption
+- Component mode
+- DTMF descriptors.
+
+The following table lists all of the commands associated with these optional features. If the option is not implemented, the command is not required.
+
+**Table 13-3 – Optional protocol messages**
+
+| Command                         | Type     | Direction                 | Description                           |
+|---------------------------------|----------|---------------------------|---------------------------------------|
+| update_ControlWord request      | Single   | AS $\Rightarrow$ Injector | Database control of control words     |
+| delete_ControlWord request      | Single   | AS $\Rightarrow$ Injector | Database control of control words     |
+| start_schedule_download request | Single   | AS $\Rightarrow$ Injector | Used to support ITU-T J.181 schedules |
+| schedule_definition request     | Multiple | AS $\Rightarrow$ Injector | Used to support ITU-T J.181 schedules |
+| schedule_component_mode request | Multiple | AS $\Rightarrow$ Injector | Used to support ITU-T J.181 schedules |
+| transmit_schedule request       | Single   | AS $\Rightarrow$ Injector | Used to support ITU-T J.181 schedules |
+
+#### 13.1.3.3 Unused commands
+
+PAMS support is an optional part of this Recommendation. In a one-way system, there may be no TCP/IP connections available, so support of a PAMS is unlikely. If a system was designed with a
+
+connection between a PAMS and an automation system, these commands could be used. Refer to clause 13.3 for a detailed look at PAMS support if required.
+
+**Table 13-4 – Unused PAMS protocol messages**
+
+| Command               | Type   | Direction             | Description |
+|-----------------------|--------|-----------------------|-------------|
+| config_request        | Single | AS $\Rightarrow$ PAMS |             |
+| config_response       | Single | AS $\Leftarrow$ PAMS  |             |
+| provisioning_request  | Single | AS $\Leftarrow$ PAMS  |             |
+| provisioning_response | Single | AS $\Rightarrow$ PAMS |             |
+| fault_request         | Single | AS $\Leftarrow$ PAMS  |             |
+| fault_response        | Single | AS $\Rightarrow$ PAMS |             |
+| AS_alive_request      | Single | AS $\Leftarrow$ PAMS  |             |
+| AS_alive_response     | Single | AS $\Rightarrow$ PAMS |             |
+
+### 13.1.4 Flow diagrams
+
+Figure 13-3 shows a normal communication flow. It assumes that a one-way connection has been set up and both the automation system (AS) and injector have been provisioned manually.
+
+![Sequence diagram showing communication flow between AS, Injector, and TS. The diagram illustrates the exchange of messages for initialization, splicing, and timing synchronization. A dashed line at the top indicates 'Serial or embedded video'. The sequence starts with AS sending 'alive_request + time()' to Injector. Injector responds with 'Initialization complete'. AS then sends 'splice_request (spliceStart_normal)' to Injector. Injector responds with 'timestamp() time' and 'splice_info_section (OON=1)'. TS receives 'splice_info_section (OON=1)' and sends 'pre-roll time' back to Injector. AS then sends 'splice_request (spliceEnd_normal)' to Injector. Injector responds with 'timestamp() time' and 'splice_info_section (OON=0)'. TS receives 'splice_info_section (OON=0)' and sends 'pre-roll time' back to Injector. Vertical lines on the right indicate 'Splice point' and 'Avail duration'.](bfca6639dd4b8480f2d96d2b61c806d9_img.jpg)
+
+The diagram is a sequence diagram with three lifelines: AS (Automation System), Injector, and TS (Timing System). 
+   
+1. A dashed line at the top labeled 'Serial or embedded video' points to the Injector lifeline.
+   
+2. AS sends a message 'alive\_request + time()' to the Injector.
+   
+3. The Injector responds with 'Initialization complete'.
+   
+4. AS sends a message 'splice\_request (spliceStart\_normal)' to the Injector.
+   
+5. The Injector responds with a bracketed message ' $\Delta\tau \Rightarrow \text{timestamp() time}$ '.
+   
+6. The Injector then sends 'splice\_info\_section (OON=1)' to the TS.
+   
+7. The TS responds with ' $\Delta\tau \Rightarrow \text{pre-roll time}$ '.
+   
+8. AS sends a message 'splice\_request (spliceEnd\_normal)' to the Injector.
+   
+9. The Injector responds with a bracketed message ' $\Delta\tau \Rightarrow \text{timestamp() time}$ '.
+   
+10. The Injector then sends 'splice\_info\_section (OON=0)' to the TS.
+   
+11. The TS responds with ' $\Delta\tau \Rightarrow \text{pre-roll time}$ '.
+   
+12. Vertical lines on the right side of the TS lifeline indicate 'Splice point' and 'Avail duration'.
+
+Sequence diagram showing communication flow between AS, Injector, and TS. The diagram illustrates the exchange of messages for initialization, splicing, and timing synchronization. A dashed line at the top indicates 'Serial or embedded video'. The sequence starts with AS sending 'alive\_request + time()' to Injector. Injector responds with 'Initialization complete'. AS then sends 'splice\_request (spliceStart\_normal)' to Injector. Injector responds with 'timestamp() time' and 'splice\_info\_section (OON=1)'. TS receives 'splice\_info\_section (OON=1)' and sends 'pre-roll time' back to Injector. AS then sends 'splice\_request (spliceEnd\_normal)' to Injector. Injector responds with 'timestamp() time' and 'splice\_info\_section (OON=0)'. TS receives 'splice\_info\_section (OON=0)' and sends 'pre-roll time' back to Injector. Vertical lines on the right indicate 'Splice point' and 'Avail duration'.
+
+**Figure 13-3 – One-way flow diagram with delayed processing**
+
+As shown, the alive\_request command flows from the automation system to the injector at least once before any normal data flow may commence. This is necessary in order to synchronize the clocks in the injector to the reference clock in the automation system. This alive request is expected to be sent periodically to keep the two clocks in sync over time. Other than this requirement, the flow diagram looks very much like the flow diagram given for the two-way systems. The main difference is the
+
+lack of any response type commands, which cannot be generated, since there is no return path in this system.
+
+There is no diagram shown for immediate message processing. It is assumed that normal one-way systems will require the delay in processing. If a system is designed with a sufficiently high speed data link, then one can use the flow diagram as shown in Figure 13-9 and simply remove the response type flows.
+
+Figure 13-4 shows how an automation system can terminate an avail early, by using the `spliceEnd_Immediate` command type in the `splice_request` command. Similar diagrams for the cancellation type commands could be drawn based on Figures 13-11, 13-12 and 13-13 in the two-way system description, by removing all response type flows.
+
+![Sequence diagram for early return in a one-way system. Lifelines: AS (Automation System), Injector, and TS (Transport System). The diagram shows the interaction between AS and Injector for video splicing, with a return path to TS. A dashed line at the top indicates 'Serial or embedded video' flow from Injector to TS. The sequence of messages is: 1. AS sends 'alive_request + time()' to Injector. 2. Injector responds with 'Initialization complete'. 3. AS sends 'splice_request (spliceStart_normal)' to Injector. 4. Injector calculates a timestamp difference Δτ = timestamp() time and sends 'splice_info_section (OON=1)' to TS. 5. Injector calculates a pre-roll time Δτ = pre-roll time. 6. A dashed line marks the 'Splice point' on the TS lifeline. 7. AS sends 'splice_request (spliceEnd_immediate)' to Injector. 8. Injector sends 'splice_info_section (cancel bit set)' to TS. 9. A dashed line marks the 'Early return Splice point' on the TS lifeline. 10. A bracket on the TS lifeline between the first and second splice points is labeled 'Avail duration'. The diagram is labeled J.287(14)_F13-4 at the bottom right.](e2c120be98ede6deb60dd341f5a9803b_img.jpg)
+
+Sequence diagram for early return in a one-way system. Lifelines: AS (Automation System), Injector, and TS (Transport System). The diagram shows the interaction between AS and Injector for video splicing, with a return path to TS. A dashed line at the top indicates 'Serial or embedded video' flow from Injector to TS. The sequence of messages is: 1. AS sends 'alive\_request + time()' to Injector. 2. Injector responds with 'Initialization complete'. 3. AS sends 'splice\_request (spliceStart\_normal)' to Injector. 4. Injector calculates a timestamp difference Δτ = timestamp() time and sends 'splice\_info\_section (OON=1)' to TS. 5. Injector calculates a pre-roll time Δτ = pre-roll time. 6. A dashed line marks the 'Splice point' on the TS lifeline. 7. AS sends 'splice\_request (spliceEnd\_immediate)' to Injector. 8. Injector sends 'splice\_info\_section (cancel bit set)' to TS. 9. A dashed line marks the 'Early return Splice point' on the TS lifeline. 10. A bracket on the TS lifeline between the first and second splice points is labeled 'Avail duration'. The diagram is labeled J.287(14)\_F13-4 at the bottom right.
+
+Figure 13-4 – One-way flow diagram for early return
+
+## 13.2 Two-way protocol – automation system to injector only
+
+### 13.2.1 System architecture summary
+
+This architecture assumes that an automation system (AS) only connects with injectors over a two-way communication link. Figure 13-5 below shows the injector as a black box within the encoder, while Figure 13-6 shows multiple external boxes containing injector instances. The essential thing is that there is a one-for-one relationship with the injector and the service carrying the related video and audio content.
+
+This architecture will assume that the PAMS is not directly connected to the automation system, so there is no automatic provisioning of the automation system, nor any automated redundancy. Redundancy switching works by the automation system attempting to connect to backup systems it has been configured for. The PAMS is shown as present because it is assumed to provide the provisioning and redundancy control for the encoders, multiplexers and injectors. But, in this scenario, the automation system must be able to provide automation control to a hot standby continuously or discover a failure and switch automatically to a cold standby.
+
+![Figure 13-5: Two-way block diagram with internal injector. The diagram shows an AS (Automation System) block on the left connected to six 'Enc/Injector' blocks. These blocks are connected to a 'MUX' (Multiplexer) block on the right. Below the 'Enc/Injector' blocks is a 'PAMS' (Packet Assembly and Management System) block. Dashed arrows indicate data flow from the 'Enc/Injector' blocks to the 'MUX' block. Solid arrows indicate control flow from the 'AS' block to the 'Enc/Injector' blocks and from the 'PAMS' block to the 'Enc/Injector' blocks. The label 'J.287(14)_F13-5' is at the bottom right.](6a7ea9d5162b0a0cfbd8d77c6cac90d1_img.jpg)
+
+Figure 13-5: Two-way block diagram with internal injector. The diagram shows an AS (Automation System) block on the left connected to six 'Enc/Injector' blocks. These blocks are connected to a 'MUX' (Multiplexer) block on the right. Below the 'Enc/Injector' blocks is a 'PAMS' (Packet Assembly and Management System) block. Dashed arrows indicate data flow from the 'Enc/Injector' blocks to the 'MUX' block. Solid arrows indicate control flow from the 'AS' block to the 'Enc/Injector' blocks and from the 'PAMS' block to the 'Enc/Injector' blocks. The label 'J.287(14)\_F13-5' is at the bottom right.
+
+**Figure 13-5 – Two-way block diagram with internal injector**
+
+![Figure 13-6: Two-way block diagram with external injector. The diagram shows an AS (Automation System) block on the left connected to a group of 'Injector' blocks (two shown with vertical dots). These 'Injector' blocks are connected to a 'MUX' (Multiplexer) block on the right. Below the 'Injector' blocks are six 'Encoder' blocks. The 'Encoder' blocks are connected to the 'MUX' block. Below the 'Encoder' blocks is a 'PAMS' (Packet Assembly and Management System) block. Dashed arrows indicate data flow from the 'Encoder' blocks to the 'MUX' block. Solid arrows indicate control flow from the 'AS' block to the 'Injector' blocks and from the 'PAMS' block to the 'Encoder' blocks. The label 'J.287(14)_F13-6' is at the bottom right.](b35ea3e304aad7d350a9902270413930_img.jpg)
+
+Figure 13-6: Two-way block diagram with external injector. The diagram shows an AS (Automation System) block on the left connected to a group of 'Injector' blocks (two shown with vertical dots). These 'Injector' blocks are connected to a 'MUX' (Multiplexer) block on the right. Below the 'Injector' blocks are six 'Encoder' blocks. The 'Encoder' blocks are connected to the 'MUX' block. Below the 'Encoder' blocks is a 'PAMS' (Packet Assembly and Management System) block. Dashed arrows indicate data flow from the 'Encoder' blocks to the 'MUX' block. Solid arrows indicate control flow from the 'AS' block to the 'Injector' blocks and from the 'PAMS' block to the 'Encoder' blocks. The label 'J.287(14)\_F13-6' is at the bottom right.
+
+**Figure 13-6 – Two-way block diagram with external injector**
+
+### 13.2.2 Automation system provisioning requirements
+
+The following system description gives the essential information required in both the AS and the injector to allow an automation system to communicate with a specific injector for a single service. This includes support for multiple injectors for the purpose of redundancy. It is expected that all of the information must be provided separately for every service in the system.
+
+#### 13.2.2.1 IP address and port
+
+The AS must be set up with the IP address and port number of each injector that is configured for the service. In general, there is expected to be two such injectors at most, the primary and the hot backup. There is no reason why a certain network could not choose to have multiple backups, but this is not generally done.
+
+The AS is expected to output the same command to each IP address and port configured. This way, a hot backup is always available to be switched in. The PAMS could switch in a backup device and expect that no DPI messages would be lost.
+
+In an N:M backup system, where one injector backs up for multiple primary injectors, it is the responsibility of the injectors to support the messages from (possibly) multiple AS sources.
+
+### 13.2.3 Service definition and DPI\_PID\_index
+
+#### 13.2.3.1 Non-component mode support
+
+For each IP address there is a list of one or more MPEG services that are supplied with DPI messages. Each MPEG service may have zero to eight DPI PIDs assigned to it. This document assumes that a service with no DPI PIDs does not need to be provisioned to an injector. The automation system and injector must both have a common agreement on what content is contained on every service. The content determines the schedule of breaks and the automation system must be sure that a break it has scheduled aligns to an avail in the video of that service. A common method of identifying a service would be by the MPEG program number. Their program number is not used by [ITU-T J.181] directly, but the PMT for that program number will have one or more PIDs defined to carry the ITU-T J.181 message stream.
+
+Some systems may define multiple PIDs for a single service. In this case, the automation system must have a method of identifying which PID is carrying specific messages. Some reasons for carrying multiple PIDs have been identified:
+
+- a method of grouping DPI messages for specific regional groups
+- separate authorization can be applied to different PIDs
+- separate functionality, such as DPI messages and segmentation messages on different PIDs.
+
+In general, the purpose assigned to a specific PID is out of scope for this signalling Recommendation. It will be a proprietary and manual process to identify the type of DPI messaging for each PID of each service.
+
+The method used for coordinating the PID assignments is done using the **DPI\_PID\_index** field in the `single_operation_message()` and `multiple_operation_message()`. The **DPI\_PID\_index** is a unique value in the entire digital compression system (DCS). It is expected that a single value of the **DPI\_PID\_index** will be assigned to each DPI PID in the DCS. The automation system would then be provisioned with a list of DPI\_PID indexes for every service.
+
+There are some systems which are sufficiently simple that there is no need for a **DPI\_PID\_index**. If there is at most a single DPI PID per injector instance, and that injector instance can be uniquely identified, then the DPI PID used to carry DPI messages is well known (i.e., there is only one choice). In this system, there is no need to provision a **DPI\_PID\_index** and it can be set to a value of zero.
+
+#### 13.2.3.2 Component mode support
+
+In a system that supports component mode DPI messages, it is necessary to supply the automation system with a more complete service definition. Within an MPEG service, there are specific components (i.e., PIDs) defined. Each component must have a component tag assigned to it. The automation system will require knowledge of the type of PID (video, audio, data) and the relative pre-roll each component has relative to video.
+
+In the simplest system, component mode is used to simply splice into some PIDs and allow other PIDs (e.g., Internet traffic) to always flow through to the consumer's receive device all of the time. In a more complex system, an automation system could produce multiple splice commands so that each component is spliced at a different time. How the timing for each component is provisioned is out of scope for this Recommendation.
+
+### 13.2.4 Multiple injector instance support
+
+The field **DPI\_PID\_index** may also be used to route messages when multiple injector instances are present in a single physical device, as is shown in Figure 13-6. If there is a single injector per device (such as in Figure 13-5) or it can be resolved to a single injector instance (using a socket for example), then this field may not be required and can be assigned a value of zero. Please consult clause 8.2.1 for specifics.
+
+There are at least two ways that this Recommendation supports multiple injectors. The exact implementation can be chosen as best fits a specific implementation.
+
+#### 13.2.4.1 IP port segmentation
+
+In a TCP/IP type configuration, each injector instance can be assigned a unique port number, or in an extreme case, a unique IP address and port number. In this architecture, each injector instance can be treated as a physical injector, even though they are in the same chassis.
+
+This type of configuration may use too many resources. Each socket connection consumes memory and processing power. Some implementations may limit the total number of sockets, which would make this method of communication have limited usefulness.
+
+The **DPI\_PID\_index** can provide a limited socket-like functionality if multiple IP sockets are not available.
+
+#### 13.2.4.2 DPI\_PID index segmentation
+
+**DPI\_PID\_index** is a field, as described above, which provides a unique identification for a single DPI\_PID within the digital compression system (DCS). A device with multiple injectors could use **DPI\_PID\_index** to route messages to a specific injector instance. For this to work, an injector would need to maintain a complete list of DPI\_PID indexes being serviced by each injector instance. When a message arrives with a non-zero **DPI\_PID\_index** set, the main controller can forward the message to the injector instance configured to handle it.
+
+### 13.2.5 Automation index (AS\_index field)
+
+When more than one automation system communicates to a single DPI\_PID on a single physical connection, each automation system should be provided with a unique **AS\_index** value. If there is only one automation system supplying information for a DPI component, the **AS\_index** can be set to zero, indicating that this parameter is not required for proper operation.
+
+In a two-way system, an individual socket connection can be established for each automation system. Even if there are multiple automation systems communicating to a single injector, the communications path is one to one. Therefore, one would not expect to use the **AS\_index** in any system (broadcast or bidirectional) that uses the IP protocol, and **AS\_index** may be set to zero.
+
+### 13.2.6 Time
+
+If automation system messages are delayed processed, using the `timestamp()` feature of the messages, then the time in both the injector and the automation system need to be coordinated within a few milliseconds of each other. The exact method of synchronization is a system design issue. Some extra options are available to a system designer when a TCP/IP connection is available. Some examples for time synchronization are given below.
+
+- NTP/SNTP
+- GPS
+- SMPTE time codes
+- The Alive requestmessage.
+
+If the system is designed to work in immediate processing mode, time synchronization is not necessary.
+
+### 13.2.7 Encryption in the automation system
+
+Encryption is an optional component in ITU-T J.181 systems. If the system is not using encryption, then information in this section may be ignored.
+
+There are three methods of supporting the encryption of ITU-T J.181 messages.
+
+1. The automation system controls the encryption because there are requirements for targeting, event related changes, or full control of an external CA system.
+2. The injector (i.e., PAMS controlled) locally encrypts messages based upon a fixed definition of the control word and algorithm for every message in a service.
+3. Shared encryption control where the AS and injector agree that a specific CW index applies to a specific group of receivers. The injector is provided the control words locally and the AS only needs to direct any one DPI message to use the CW. The rules for defining what a CW means needs to be worked out for the system, so that the AS and injector have a common understanding of the groups.
+
+There are three commands used to support encryption:
+
+- Encrypt DPI Data
+- Update Control Word
+- Delete Control Word.
+
+In complex systems (Method 1), the encryption parameters could change on an event basis. Encryption could also be used as a form of targeting messages, so multiple messages could be generated per event, each with different encryption parameters. A different CW\_Index may be applied per message to determine how the message is encrypted.
+
+A device upstream of the injector should control access and/or targeting of DPI messages and would need to be provisioned to do so. It may not be an automation system per se, but it would use this protocol and it would appear to the injector as an automation system.
+
+NOTE – The database of control words is unique to an injector instance. Due to the potentially large size of the database, an injector may choose to limit the maximum number of control words that are stored simultaneously.
+
+In summary:
+
+If the AS implements the complete conditional access system (Method 1), it would use all of the encryption commands. If the AS implemented no conditional access (Method 2), then the AS should never send any of the commands. If the AS has only control of which messages are encrypted (Method 3), then only the "Encrypt DPI Data" command is ever sent by the AS.
+
+Access security is a concern. The environment between the AS and the injector should have physical security at a minimum.
+
+### 13.2.8 DTMF descriptors
+
+If the automation system wishes to control the output of analogue cue tones coincident with the digital cue tones, then it must be provisioned with the DTMF tone sequence and the pre-roll timing.
+
+In advanced applications, it is possible that each tone sequence is unique. An example might be a limited form of targeting using different digits sequences. The automation system needs to be the source of the DTMF information in order to provide such control.
+
+In simple systems that have a fixed relationship of the DTMF tone sequence and timing, the injector could be directly provisioned with this information and there would be no need for automation support.
+
+### 13.2.9 Automation system $\leftrightarrow$ Injector messages
+
+#### 13.2.9.1 Supported messages
+
+The following table gives the various commands that can be used between the automation system and the injector.
+
+**Table 13-5 – Supported protocol messages**
+
+| Command                  | Type   | Direction                 | Description                                                                                                                                                                                                                                                |
+|--------------------------|--------|---------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| init_request             | Single | AS $\Rightarrow$ Injector | Sent immediately after a socket connection has been established                                                                                                                                                                                            |
+| init_response            | Single | AS $\Leftarrow$ Injector  | Acknowledgement for the Init request                                                                                                                                                                                                                       |
+| splice_request           | Either | AS $\Rightarrow$ Injector | Sent any time a splice is to be signalled                                                                                                                                                                                                                  |
+| inject_response          | Single | AS $\Leftarrow$ Injector  | Acknowledgement for splice request – returned to immediately acknowledge receipt of the command                                                                                                                                                            |
+| inject_complete_response | Single | AS $\Leftarrow$ Injector  | Acknowledgement for splice request – returned after the DPI message has been injected into the transport.<br>May be returned immediately after the inject response if immediate mode timing is used.<br>May be delayed if time-stamped processing is used. |
+| alive_request            | Single | AS $\Rightarrow$ Injector | Sent periodically to keep the connection active.<br>May include the current time so that the AS and injector can maintain a synchronized timebase.                                                                                                         |
+| alive_response           | Single | AS $\Leftarrow$ Injector  | Acknowledgement for the alive request                                                                                                                                                                                                                      |
+| time_signal_request      | Either | AS $\Rightarrow$ Injector | Generates an ITU-T J.181 time signal message. While either type may be used, time signal will normally have a descriptor associated with it, making the multiple command type the normal type.                                                             |
+| inject_response          | Single | AS $\Leftarrow$ Injector  | Acknowledgement for time signal – returned to immediately acknowledge receipt of the command                                                                                                                                                               |
+| inject_complete_response | Single | AS $\Leftarrow$ Injector  | Acknowledgement for time signal – returned after the DPI message has been injected into the transport.<br>May be returned immediately after the splice response if immediate mode timing is used.<br>May be delayed if time-stamped processing is used.    |
+
+**Table 13-6 – Supported protocol messages**
+
+| <b>Command</b>              | <b>Type</b> | <b>Direction</b>          | <b>Description</b>                                                                                                                                                                                                                                                |
+|-----------------------------|-------------|---------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| splice_null request         | Single      | AS $\Rightarrow$ Injector | Generates an ITU-T J.181 nullmessage.                                                                                                                                                                                                                             |
+| inject_response             | Single      | AS $\Leftarrow$ Injector  | Acknowledgement for "Splice Null" – returned to immediately acknowledge receipt of the command.                                                                                                                                                                   |
+| inject_complete_response    | Single      | AS $\Leftarrow$ Injector  | Acknowledgement for "Splice Null" – returned after the DPI message has been injected into the transport.<br>May be returned immediately after the splice response if immediate mode timing is used.<br>May be delayed if time-stamped processing is used.         |
+| proprietary_command request | Either      | AS $\Rightarrow$ Injector | A generic normal command. This is used for future support of standard commands or proprietary extension. Like other basic commands, one may attach advanced commands like the inject section.                                                                     |
+| inject_response             | Single      | AS $\Leftarrow$ Injector  | Acknowledgement for "Proprietary Command" – returned to immediately acknowledge receipt of the command.                                                                                                                                                           |
+| inject_complete_response    | Single      | AS $\Leftarrow$ Injector  | Acknowledgement for "Proprietary Command" – returned after the DPI message has been injected into the transport.<br>May be returned immediately after the splice response if immediate mode timing is used.<br>May be delayed if time-stamped processing is used. |
+
+#### 13.2.9.2 Optional commands
+
+Some features are deemed optional in an automation system:
+
+- Encryption
+- Component mode
+- DTMF descriptors.
+
+The following table lists all of the commands associated with these optional features. If the option is not implemented, the command is not required.
+
+**Table 13-7 – Optional protocol messages**
+
+| Command                         | Type     | Direction                 | Description                                                                                                                                                                |
+|---------------------------------|----------|---------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| update_ControlWord request      | Single   | AS $\Rightarrow$ Injector | <ul style="list-style-type: none"> <li>This allows the AS to download a new CW for use in encrypted messages.</li> </ul>                                                   |
+| general_response                | Single   | AS $\Leftarrow$ Injector  |                                                                                                                                                                            |
+| delete_Control_Word request     | Single   | AS $\Rightarrow$ Injector | <ul style="list-style-type: none"> <li>This allows the AS to delete an active CW. Once deleted, an injector can flag an error if any attempt is made to use it.</li> </ul> |
+| general_response                | Single   | AS $\Leftarrow$ Injector  |                                                                                                                                                                            |
+| start_schedule_download request | Single   | AS $\Rightarrow$ Injector | <ul style="list-style-type: none"> <li>Indicates to an injector that it should start collecting schedule information.</li> </ul>                                           |
+| inject_response                 | Single   | AS $\Leftarrow$ Injector  |                                                                                                                                                                            |
+| schedule_definition request     | Multiple | AS $\Rightarrow$ Injector | <ul style="list-style-type: none"> <li>Used to download a single schedule entry into the injector's database.</li> </ul>                                                   |
+| inject_response                 | Single   | AS $\Leftarrow$ Injector  |                                                                                                                                                                            |
+| schedule_component_mode request | Multiple | AS $\Rightarrow$ Injector | <ul style="list-style-type: none"> <li>Used as a supplemental command for "Schedule Definition" to indicate that a component splice is being scheduled.</li> </ul>         |
+| inject_response                 | Single   | AS $\Leftarrow$ Injector  |                                                                                                                                                                            |
+| transmit_schedule request       | Single   | AS $\Rightarrow$ Injector | <ul style="list-style-type: none"> <li>The automation system uses this command to tell an injector to send the accumulated schedule information.</li> </ul>                |
+| inject_response                 | Single   | AS $\Leftarrow$ Injector  |                                                                                                                                                                            |
+| inject_complete_response        |          | AS $\Leftarrow$ Injector  | <ul style="list-style-type: none"> <li>Indicates the schedule data has been placed in the outgoing TS.</li> </ul>                                                          |
+
+#### 13.2.9.3 Unused commands
+
+With no PAMS supported, PAMS-related commands are not used.
+
+**Table 13-8 – Unused PAMS protocol messages**
+
+| Command               | Type   | Direction             | Description |
+|-----------------------|--------|-----------------------|-------------|
+| config_request        | Single | AS $\Rightarrow$ PAMS |             |
+| config_response       | Single | AS $\Leftarrow$ PAMS  |             |
+| provisioning_request  | Single | AS $\Leftarrow$ PAMS  |             |
+| provisioning_response | Single | AS $\Rightarrow$ PAMS |             |
+| fault_request         | Single | AS $\Rightarrow$ PAMS |             |
+| fault_response        | Single | AS $\Leftarrow$ PAMS  |             |
+| AS_alive_request      | Single | AS $\Leftarrow$ PAMS  |             |
+| AS_alive_response     | Single | AS $\Rightarrow$ PAMS |             |
+
+### 13.2.10 Flow diagrams
+
+Figure 13-7 shows how the initialization of a TCP/IP two-way connection is set up. The client (automation system) must first establish a socket to the server (injector). The init\_request() message is sent to establish the socket connection. In a system that is using keep\_alive() messages for time synchronization, the keep\_alive() message must also be sent to synchronize time before any normal message traffic that uses delay processing is sent.
+
+![Two-way flow diagram for initialization showing communication between AS (Client), Injector (Server), and TS. The diagram illustrates the sequence of messages for initialization, including socket opening, splice_init requests, and alive requests. It also shows periods of normal traffic between the AS, injector, and TS.](3bf1696c3034743b5ab07a0b5e398347_img.jpg)
+
+```
+
+sequenceDiagram
+    participant AS as AS (Client)
+    participant Injector as Injector (Server)
+    participant TS as TS
+
+    Note over AS, Injector: TCP/IP
+    AS->>Injector: Open a socket
+    AS->>Injector: splice_init_request
+    Injector-->>AS: splice_init_response
+    Note right of Injector: Initialization complete
+    AS->>Injector: alive_request
+    Injector-->>AS: alive_response
+    Note right of Injector: Required if time() needs synchronization
+    Note over AS, Injector, TS: Normal AS, injector and TS traffic
+    AS->>Injector: alive_request
+    Injector-->>AS: alive_response
+    Note right of Injector: Repeat as required
+    Note over AS, Injector, TS: Normal AS, injector and TS traffic
+  
+```
+
+J.287(14)\_F13-7
+
+Two-way flow diagram for initialization showing communication between AS (Client), Injector (Server), and TS. The diagram illustrates the sequence of messages for initialization, including socket opening, splice\_init requests, and alive requests. It also shows periods of normal traffic between the AS, injector, and TS.
+
+**Figure 13-7 – Two-way flow diagram for initialization**
+
+Figure 13-8 shows a normal communication flow. It assumes that a TCP/IP connection has been set up and both the automation system (AS) and injector have been provisioned manually. This diagram shows the system without any PAMS support for automatic provisioning of the automation system. For normal communications, a single message will produce a single MPEG section. For example, a splice request with a command type "spliceStart\_normal" will produce a splice\_info\_section containing a splice\_insert command with out\_of\_network (OON) set to a one. When an immediately processed command is sent that produces an MPEG section, there are two responses returned at the same time. They both may be returned in the same datagram if desired.
+
+![Sequence diagram showing the interaction between AS, Injector, and TS for a two-way flow with delayed processing. The diagram includes messages like splice_request (spliceStart_normal), splice_response, splice_complete_response, and splice_info_section (OON=1). It also shows timing intervals like Δτ => timestamp() time, Δτ => pre-roll time, and Δτ => avail duration, with splice points indicated on the TS timeline.](32d36dfe7dc75b7c63f8edf0f28e4009_img.jpg)
+
+```
+
+sequenceDiagram
+    participant AS
+    participant Injector
+    participant TS
+    Note over AS, Injector: TCP/IP
+    Note over AS, Injector: Initialization complete
+    AS->>Injector: splice_request (spliceStart_normal)
+    Injector->>AS: splice_response
+    Note right of Injector: Δτ => timestamp() time
+    Injector->>TS: splice_info_section (OON=1)
+    Note right of TS: Δτ => pre-roll time
+    TS->>TS: Splice point
+    Injector->>AS: splice_complete_response
+    AS->>Injector: splice_request (spliceEnd_normal)
+    Injector->>AS: splice_response
+    Note right of Injector: Δτ => timestamp() time
+    Note right of TS: Δτ => avail duration
+    Injector->>TS: splice_info_section (OON=0)
+    Note right of TS: Δτ => pre-roll time
+    TS->>TS: Splice point
+    Injector->>AS: splice_complete_response
+
+```
+
+The diagram illustrates a sequence of messages between three entities: AS (Application Server), Injector, and TS (Transport System). A dashed line at the top labeled 'TCP/IP' spans between AS and Injector. The sequence starts with 'Initialization complete' between AS and Injector. The first splice sequence begins with 'splice\_request (spliceStart\_normal)' from AS to Injector, followed by 'splice\_response' from Injector to AS. A bracket on the Injector's timeline indicates  $\Delta\tau \Rightarrow \text{timestamp() time}$ . The Injector then sends 'splice\_info\_section (OON=1)' to TS. A bracket on the TS timeline indicates  $\Delta\tau \Rightarrow \text{pre-roll time}$ , leading to a 'Splice point'. The Injector then sends 'splice\_complete\_response' to AS. The second splice sequence begins with 'splice\_request (spliceEnd\_normal)' from AS to Injector, followed by 'splice\_response' from Injector to AS. A bracket on the Injector's timeline indicates  $\Delta\tau \Rightarrow \text{timestamp() time}$ . The Injector then sends 'splice\_info\_section (OON=0)' to TS. A bracket on the TS timeline indicates  $\Delta\tau \Rightarrow \text{pre-roll time}$ , leading to another 'Splice point'. A bracket on the TS timeline between the two splice points indicates  $\Delta\tau \Rightarrow \text{avail duration}$ . The Injector then sends 'splice\_complete\_response' to AS. The diagram ends with the identifier 'J.287(14)\_F13-8'.
+
+Sequence diagram showing the interaction between AS, Injector, and TS for a two-way flow with delayed processing. The diagram includes messages like splice\_request (spliceStart\_normal), splice\_response, splice\_complete\_response, and splice\_info\_section (OON=1). It also shows timing intervals like Δτ => timestamp() time, Δτ => pre-roll time, and Δτ => avail duration, with splice points indicated on the TS timeline.
+
+**Figure 13-8 – Two-way flow diagram with delayed processing**
+
+The diagram shows the *splice\_request* for both a normal message that directs a splice to exit the network feed and the command to return to the network feed at the end of the *avail*. The *splice\_request* contains a *command\_type* field that gives the type of command, as defined in Table 9-6. Figure 13-8 shows a system that uses delayed processing for both the start and the end of the *avail* period. Figure 13-9 shows the same normal system flow diagram, but it uses the "process immediately" mode. These commands are identified by having a *time\_type* value of zero in the *timestamp()* field. This system assumes that the TCP/IP connection has relatively low latency and that the injector can output a *splice\_info\_section* in the same video frame as the command arrives.
+
+![Sequence diagram showing two-way flow with immediate processing between AS, Injector, and TS entities over a TCP/IP connection. The diagram illustrates two splice operations. In the first, AS sends a splice_request (spliceStart_normal) to Injector, which responds with splice_info_section (OON=1) to TS. TS returns splice_response and splice_complete_response to Injector, which then responds to AS. A time interval Δτ (pre-roll time) is marked between the response and the next splice point. The second operation follows a similar pattern but uses splice_end_normal and splice_info_section (OON=0). A time interval Δτ (avail duration) is marked between the two splice points. The diagram is labeled J.287(14)_F13-9.](c6212a3b14736d6a8c81ace75ae94ccf_img.jpg)
+
+```
+
+sequenceDiagram
+    participant AS
+    participant Injector
+    participant TS
+    Note over AS, Injector: TCP/IP
+    Note right of AS: Initialization complete
+    AS->>Injector: splice_request (spliceStart_normal)
+    Injector->>TS: splice_info_section (OON=1)
+    TS-->>Injector: splice_response
+    TS-->>Injector: splice_complete_response
+    Note right of TS: Δτ => pre-roll time
+    Injector-->>AS: splice_response
+    Injector-->>AS: splice_complete_response
+    Note right of Injector: Splice point
+    AS->>Injector: splice_request (splice_end_normal)
+    Injector->>TS: splice_info_section (OON=0)
+    TS-->>Injector: splice_response
+    TS-->>Injector: splice_complete_response
+    Note right of TS: Δτ => avail duration
+    Injector-->>AS: splice_response
+    Injector-->>AS: splice_complete_response
+    Note right of Injector: Splice point
+  
+```
+
+Sequence diagram showing two-way flow with immediate processing between AS, Injector, and TS entities over a TCP/IP connection. The diagram illustrates two splice operations. In the first, AS sends a splice\_request (spliceStart\_normal) to Injector, which responds with splice\_info\_section (OON=1) to TS. TS returns splice\_response and splice\_complete\_response to Injector, which then responds to AS. A time interval Δτ (pre-roll time) is marked between the response and the next splice point. The second operation follows a similar pattern but uses splice\_end\_normal and splice\_info\_section (OON=0). A time interval Δτ (avail duration) is marked between the two splice points. The diagram is labeled J.287(14)\_F13-9.
+
+**Figure 13-9 – Two-way flow diagram with immediate processing**
+
+These diagrams do not show the initialization sequence for the TCP/IP connection. Nor does it show the alive request and response which are exchanged periodically.
+
+Figure 13-10 shows a case of abnormal termination of an avail. It starts with a normal sequence (normal splice: out\_of\_network = 1) for the start of the avail using the delayed method of processing. If a network operator has detected some abnormal programming requirements, they can initiate an emergency return to network. This uses a splice\_request with a splice\_return\_early command type. Due to the emergency nature of this command, one would expect it to be sent with a zero for the time\_type field which forces an immediate processing of the early return. The receive device, when it detects a splice\_info\_section with the immediate bit set in a return to network message (return: out\_of\_network = 0), will abort any inserted content it is playing and return to the network immediately.
+
+![Sequence diagram for early return splice between AS, Injector, and TS.](f78d2e126f00fcc5d8d9797ca410cc09_img.jpg)
+
+```
+
+sequenceDiagram
+    participant AS
+    participant Injector
+    participant TS
+    Note over AS, Injector: TCP/IP
+    AS->>Injector: Initialization complete
+    AS->>Injector: splice_request (spliceStart_normal)
+    Injector->>AS: splice_response
+    Note right of Injector: Δτ ⇒ timestamp() time
+    Injector->>TS: splice_info_section (OON=1)
+    Injector->>AS: splice_complete_response
+    Note right of Injector: Δτ ⇒ pre-roll time
+    TS->>TS: Splice point
+    AS->>Injector: splice_request (spliceEnd_immediate)
+    Injector->>AS: splice_response
+    Note right of Injector: Δτ ⇒ avail duration
+    Injector->>TS: splice_info_section (OON=0)  
+(immediate bit set)
+    Injector->>AS: splice_complete_response
+    TS->>TS: Early return  
+Splice point
+
+```
+
+J.287(14) F 13-10
+
+Sequence diagram for early return splice between AS, Injector, and TS.
+
+**Figure 13-10 – Two-way flow diagram for early return**
+
+In some special circumstances, when a long `timestamp()` is used for delayed processing, or there is a long pre-roll, an operator may decide that a splice in progress needs to be cancelled. When the automation system wishes to cancel a command soon after it has been sent, it may not know if it has been processed or if a section has been sent in the output transport. In this case, it sends a `splice_cancel` as shown in Figures 13-11, 13-12 or Figure 13-13. If the automation system is sure that an insertion is in progress, they should send the `spliceEnd_Immediate` instead of the cancel command.
+
+Figure 13-11 shows a cancel that is sent before the `splice_info_section` is generated. In this case, the section generation is cancelled. Also, the `inject_complete_response` for the original message will not be returned.
+
+![Sequence diagram for Figure 13-11 showing two-way cancellation before being processed. The diagram involves three entities: AS, Injector, and TS. The AS and Injector communicate over TCP/IP. The AS sends an 'Initialization complete' message to the Injector. The AS sends a 'splice_request (spliceStart_normal)' to the Injector, which responds with 'splice_response'. Then the AS sends a 'splice_request (splice_cancel)' to the Injector, which responds with 'splice_response' and 'splice_complete_response'. A bracket indicates a time interval Δτ => timestamp() time between the two requests. A dashed arrow for 'splice_complete_response' and 'splice_info_section (OON=1)' indicates these are not sent. A note indicates that 'Normal traffic is never sent due to cancellation'. The diagram is labeled J.287(14)_F13-11.](e404de9a69c05473fbd6af28ee32311b_img.jpg)
+
+```
+
+sequenceDiagram
+    participant AS
+    participant Injector
+    participant TS
+    Note over AS, Injector: TCP/IP
+    AS->>Injector: Initialization complete
+    AS->>Injector: splice_request (spliceStart_normal)
+    Injector-->>AS: splice_response
+    Note right of Injector: Δτ => timestamp() time
+    AS->>Injector: splice_request (splice_cancel)
+    Injector-->>AS: splice_response
+    Injector-->>AS: splice_complete_response
+    Injector--xTS: splice_info_section (OON=1)
+    Injector--xAS: splice_complete_response
+    Note right of TS: Normal traffic is never sent due to cancellation
+
+```
+
+J.287(14)\_F13-11
+
+Sequence diagram for Figure 13-11 showing two-way cancellation before being processed. The diagram involves three entities: AS, Injector, and TS. The AS and Injector communicate over TCP/IP. The AS sends an 'Initialization complete' message to the Injector. The AS sends a 'splice\_request (spliceStart\_normal)' to the Injector, which responds with 'splice\_response'. Then the AS sends a 'splice\_request (splice\_cancel)' to the Injector, which responds with 'splice\_response' and 'splice\_complete\_response'. A bracket indicates a time interval Δτ => timestamp() time between the two requests. A dashed arrow for 'splice\_complete\_response' and 'splice\_info\_section (OON=1)' indicates these are not sent. A note indicates that 'Normal traffic is never sent due to cancellation'. The diagram is labeled J.287(14)\_F13-11.
+
+**Figure 13-11 – Two-way cancellation before being processed**
+
+Figure 13-12 shows a cancel command being sent after a splice\_info\_section has been placed in the output multiplex. In this case, the injector must create a splice\_info\_section formatted with the cancel bit set.
+
+![Sequence diagram for Figure 13-12 showing two-way cancellation after being processed. The diagram involves three entities: AS, Injector, and TS. The AS and Injector communicate over TCP/IP. The AS sends an 'Initialization complete' message to the Injector. The AS sends a 'splice_request (spliceStart_normal)' to the Injector, which responds with 'splice_response'. A bracket indicates Δτ => timestamp() time. The Injector sends a 'splice_info_section (OON=1)' to the TS. The Injector sends a 'splice_complete_response' to the AS. Then the AS sends a 'splice_request (splice_cancel)' to the Injector, which responds with 'splice_response' and 'splice_complete_response'. A bracket indicates a time interval Δτ => pre-roll time between the first and second splice_info_sections. The Injector sends a 'splice_info_section (cancel bit set)' to the TS. A note indicates 'Splice point cancelled'. The diagram is labeled J.287(14)_F13-12.](2f587210e4f97c32758c5972e2e83d20_img.jpg)
+
+```
+
+sequenceDiagram
+    participant AS
+    participant Injector
+    participant TS
+    Note over AS, Injector: TCP/IP
+    AS->>Injector: Initialization complete
+    AS->>Injector: splice_request (spliceStart_normal)
+    Injector-->>AS: splice_response
+    Note right of Injector: Δτ => timestamp() time
+    Injector->>TS: splice_info_section (OON=1)
+    Injector-->>AS: splice_complete_response
+    AS->>Injector: splice_request (splice_cancel)
+    Injector-->>AS: splice_response
+    Note right of Injector: Δτ => pre-roll time
+    Injector->>TS: splice_info_section (cancel bit set)
+    Injector-->>AS: splice_complete_response
+    Note right of TS: Splice point cancelled
+
+```
+
+J.287(14)\_F13-12
+
+Sequence diagram for Figure 13-12 showing two-way cancellation after being processed. The diagram involves three entities: AS, Injector, and TS. The AS and Injector communicate over TCP/IP. The AS sends an 'Initialization complete' message to the Injector. The AS sends a 'splice\_request (spliceStart\_normal)' to the Injector, which responds with 'splice\_response'. A bracket indicates Δτ => timestamp() time. The Injector sends a 'splice\_info\_section (OON=1)' to the TS. The Injector sends a 'splice\_complete\_response' to the AS. Then the AS sends a 'splice\_request (splice\_cancel)' to the Injector, which responds with 'splice\_response' and 'splice\_complete\_response'. A bracket indicates a time interval Δτ => pre-roll time between the first and second splice\_info\_sections. The Injector sends a 'splice\_info\_section (cancel bit set)' to the TS. A note indicates 'Splice point cancelled'. The diagram is labeled J.287(14)\_F13-12.
+
+**Figure 13-12 – Two-way cancellation after being processed**
+
+Figure 13-13 shows a cancel command being sent after a splice\_info\_section has been placed in the output multiplex and after the splice time indicated has passed. In this case, the injector must create a splice\_info\_section formatted as a spliceEnd\_immediate type command to abort the insertion that is in progress.
+
+![Sequence diagram showing a two-way flow for canceling a splice after the splice point. Lifelines: AS, Injector, TS. The sequence starts with Initialization complete, followed by splice_request (spliceStart_normal), splice_response, splice_info_section (OON=1), splice_complete_response, splice_request (splice_cancel), splice_response, and splice_complete_response. Time intervals Δτ are indicated between splice_info_section and splice point, and between splice point and early return splice point.](e9f6a9e6beb9ae97b392bf38b93ad748_img.jpg)
+
+```
+
+sequenceDiagram
+    participant AS
+    participant Injector
+    participant TS
+    Note over AS, Injector: TCP/IP
+    AS->>Injector: splice_request (spliceStart_normal)
+    Injector-->>AS: splice_response
+    Note right of Injector: Δτ => timestamp() time
+    Injector->>TS: splice_info_section (OON=1)
+    Note right of TS: Δτ => pre-roll time
+    TS-->>Injector: splice_complete_response
+    Note right of Injector: Splice point
+    AS->>Injector: splice_request (splice_cancel)
+    Injector-->>AS: splice_response
+    Injector->>TS: splice_info_section (OON=0 immediate)
+    TS-->>Injector: splice_complete_response
+    Note right of TS: Early return Splice point
+    Note right of TS: J.287(14)_F13-13
+  
+```
+
+Sequence diagram showing a two-way flow for canceling a splice after the splice point. Lifelines: AS, Injector, TS. The sequence starts with Initialization complete, followed by splice\_request (spliceStart\_normal), splice\_response, splice\_info\_section (OON=1), splice\_complete\_response, splice\_request (splice\_cancel), splice\_response, and splice\_complete\_response. Time intervals Δτ are indicated between splice\_info\_section and splice point, and between splice point and early return splice point.
+
+Figure 13-13 – Two-way flow diagram cancel after splice point
+
+## 13.3 Two-way protocol – automation system to injector with PAMS
+
+### 13.3.1 System architecture summary
+
+This architecture assumes that an automation system (AS) connects with injectors over a two-way communication link. The automation system also connects with a provisioning and alarm management system (PAMS) to be automatically provisioned with information about the services available in the network. The PAMS can also provide support for controlled redundancy of injectors and indicate to an automation system how to reconfigure to maintain service. Figure 13-14 below shows the injector as a black box within the encoder, while Figure 13-15 shows multiple external boxes containing injector instances. The essential thing is that there is a one-for-one relationship with the injector and the service carrying the related video and audio content.
+
+A failure of an injector in this system can be detected by either an AS or the PAMS. If the AS detects a failure it can notify the PAMS of this fact. If the PAMS detects a failure it can take corrective action immediately. In both cases, the PAMS is responsible for reprovisioning the injectors and informing the AS of the new configuration. The AS can then attempt to reconnect to the replacement injector.
+
+![Figure 13-14: Two-way block diagram with internal injector. The diagram shows an AS (Automation System) block on the left connected to a PAMS (Packet Management System) block at the bottom via a double-headed dashed arrow. Between AS and PAMS are six 'Enc/Injector' blocks. Each 'Enc/Injector' block has a solid arrow pointing to the AS and a dashed arrow pointing to a 'MUX' (Multiplexer) block on the right. The 'MUX' block has a dashed arrow pointing to the PAMS block. A small label 'J.287(14)_F13-14' is at the bottom right of the diagram.](0adfaa8c2562a9fe3a8a96165d7d59a3_img.jpg)
+
+Figure 13-14: Two-way block diagram with internal injector. The diagram shows an AS (Automation System) block on the left connected to a PAMS (Packet Management System) block at the bottom via a double-headed dashed arrow. Between AS and PAMS are six 'Enc/Injector' blocks. Each 'Enc/Injector' block has a solid arrow pointing to the AS and a dashed arrow pointing to a 'MUX' (Multiplexer) block on the right. The 'MUX' block has a dashed arrow pointing to the PAMS block. A small label 'J.287(14)\_F13-14' is at the bottom right of the diagram.
+
+**Figure 13-14 – Two-way block diagram with internal injector**
+
+![Figure 13-15: Two-way block diagram with external injector. The diagram shows an AS (Automation System) block on the left connected to a PAMS (Packet Management System) block at the bottom via a double-headed dashed arrow. Between AS and PAMS are six 'Encoder' blocks. Each 'Encoder' block has a dashed arrow pointing to a 'MUX' (Multiplexer) block on the right. The 'MUX' block has a dashed arrow pointing to the PAMS block. Above the 'Encoder' blocks is a box containing two 'Injector' blocks, with vertical dots between them. This box has a solid arrow pointing to the AS and a dashed arrow pointing to the 'MUX' block. A small label 'J.287(14)_F13-15' is at the bottom right of the diagram.](b1784a5cbeeb3d9fb9e60b333019c721_img.jpg)
+
+Figure 13-15: Two-way block diagram with external injector. The diagram shows an AS (Automation System) block on the left connected to a PAMS (Packet Management System) block at the bottom via a double-headed dashed arrow. Between AS and PAMS are six 'Encoder' blocks. Each 'Encoder' block has a dashed arrow pointing to a 'MUX' (Multiplexer) block on the right. The 'MUX' block has a dashed arrow pointing to the PAMS block. Above the 'Encoder' blocks is a box containing two 'Injector' blocks, with vertical dots between them. This box has a solid arrow pointing to the AS and a dashed arrow pointing to the 'MUX' block. A small label 'J.287(14)\_F13-15' is at the bottom right of the diagram.
+
+**Figure 13-15 – Two-way block diagram with external injector**
+
+### 13.3.2 Automation system provisioning requirements
+
+The following system description gives the essential information required in the AS to allow an automation system to communicate with a specific injector for a single service. This includes support for multiple injectors for the purpose of redundancy. It is expected that all of the information must be provided separately for every service in the system. The PAMS is expected to provide the detailed information on services and injector communications to the automation system.
+
+#### 13.3.2.1 IP address and port for PAMS
+
+The automation system will require the IP address and port for each PAMS in the system. A normal system is expected to have a single active PAMS controlling a set of encoders and matching injectors. Some systems may have a redundant PAMS available. In this case, the AS may wish to establish initial communications with the backup PAMS, but normal operation communications is with the currently active PAMS.
+
+The PAMS will supply the IP address and port information for all injectors after the initial connection has been established.
+
+#### 13.3.2.2 Service name
+
+The AS and injectors must agree on what DPI data is associated with what content and for which services that the content is being carried on. The only field available to synchronize the three devices (AS, PAMS and injector) is through the use of the text string **service\_name**.
+
+The automation system must be manually provisioned with a text service name that associates a list of splice times for the content it is controlling. The PAMS is also manually provisioned with a **service\_name** for each program number it is controlling. For each service, the PAMS supplies a list of **DPI\_PID\_index**, one for each DPI PID in the service. The PAMS may optionally supply a list of components contained in the service, by supplying the **component\_tags** for each elementary stream PID.
+
+One should note that it is possible to associate a video and audio with more than one service in some systems. It is also possible, by extension, to associate the same **DPI\_PID\_index** to multiple services. In a complete service definition, duplicate **DPI\_PID\_index** values may be present. If this is found, one must assume that it is also the exact same physical DPI PID stream and the AS need only send the AS to injector commands to each physical device once.
+
+It is also possible that the same **DPI\_PID\_index** value is found associated with multiple IP address and ports. The physical DPI PID stream is identical. In this case, the PAMS is indicating to the automation system that there are multiple "Hot Backup" injectors active. The AS cannot know which of these many devices is the active device, and must direct AS to injector commands to all physical devices.
+
+Note that in some systems, the **DPI\_PID\_index** is not required, and that **DPI\_PID\_index** will be set to zero in this special case. Therefore, the uniqueness requirement described above only applies when **DPI\_PID\_index** is non-zero. The service name must always be a unique text string. The text string is case sensitive.
+
+#### 13.3.2.3 Time
+
+If automation system messages are delayed processed in the injector by using the **timestamp()** feature of the messages, then the time in both the injector and the automation system needs to be coordinated within a few milliseconds of each other. The time can be synchronized using any of the methods described in clause 13.2.6.
+
+#### 13.3.2.4 Encryption in the automation system
+
+Encryption is an optional component in ITU-T J.181 systems. If the system is not using encryption, then information in this section may be ignored. The PAMS has no direct control over how encryption should be used. Therefore, encryption must be manually provisioned as described in clause 13.2.7.
+
+#### 13.3.2.5 DTMF descriptors
+
+If the automation system wishes to control the output of analogue cue tones coincident with the digital cue tones, then it must be provisioned with the DTMF tone sequence and the pre-roll timing. The PAMS has no direct control over how DTMF tones are used by the automation system. Therefore, they will need to be manually provisioned as described in clause 13.2.8.
+
+### 13.3.3 PAMS supplied information
+
+#### 13.3.3.1 Injector configuration
+
+The PAMS is the device that is aware of the network interconnections, such as which injector instance is associated with each physical device. Using this configuration information, the PAMS can supply the automation system with the exact IP address and port for each service in the system.
+
+#### 13.3.3.2 Multiple injector instance support
+
+Multiple physical injectors may require more than simply the IP address of the device to enable the correct routing of the AS to injector traffic. In this case, it is the PAMS that determines if the injector instance can be identified by IP address, **DPI\_PID\_index** or a combination of both fields.
+
+#### 13.3.3.3 Service information
+
+The PAMS must be aware of the exact configuration of each MPEG service in the system. If component mode is being used, it must also be aware of all of the components present and the associated component\_tags. This information must be supplied to the automation system so that it can direct the DPI commands to the correct injector instance.
+
+#### 13.3.3.4 Automation index (AS\_index field)
+
+When more than one automation system communicates to a single DPI PID on a single hardwired connection (such as serial or USB communications), each automation system should be provided with a unique **AS\_index** value. The PAMS can determine if an **AS\_index** is required and can inform the AS of the value of **AS\_index** that it should use when communicating to the injector. A value of zero can be used if **AS\_index** is not required for proper operation, for example when TCP/IP is used. In TCP/IP systems, each connection can have a unique instance of the socket to determine which automation system is supplying the command.
+
+### 13.3.4 Automation system ↔ Injector messages
+
+#### 13.3.4.1 Supported messages
+
+The messages exchanged between the automation system and the injector are the same as those used for the two-way system without PAMS support. Refer to Table 13-5 and Table 13-6 for a summary of the available commands.
+
+#### 13.3.4.2 Optional commands
+
+Some features are deemed optional in an automation system:
+
+- encryption
+- component mode
+- DTMF descriptors.
+
+The optional messages exchanged between the automation system and the injector are the same as those used for the two-way system without PAMS support. Refer to Table 13-7 for a summary of the available commands.
+
+### 13.3.5 Automation system ↔ PAMS messages
+
+With PAMS support, the PAMS-related commands are used as described in clause 9.8.9. The commands available are summarized in Table 13-9.
+
+**Table 13-9 – PAMS protocol messages**
+
+| Command               | Type   | Direction             | Description                                                                                                                                                                                            |
+|-----------------------|--------|-----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| config_request        | Single | AS $\Rightarrow$ PAMS | Used on initial connection of the automation system to a PAMS                                                                                                                                          |
+| config_response       | Single | AS $\Leftarrow$ PAMS  | Acknowledges the config_request                                                                                                                                                                        |
+| provisioning_request  | Single | AS $\Leftarrow$ PAMS  | This is sent on the reset of a PAMS, after a config_request, whenever there is a change in the service definitions, or a change in the service each injector has assigned to it.                       |
+| provisioning_response | Single | AS $\Rightarrow$ PAMS | Acknowledges the provisioning_request                                                                                                                                                                  |
+| fault_request         | Single | AS $\Rightarrow$ PAMS | This command is sent by the AS whenever it detects a failure of an injector. The PAMS should reconfigure the injectors and return a provisioning_request when the backup injector has been configured. |
+| fault_response        | Single | AS $\Leftarrow$ PAMS  | Acknowledges the fault_request                                                                                                                                                                         |
+| AS_alive_request      | Single | AS $\Leftarrow$ PAMS  | Sent periodically by the PAMS when a permanent connection has been established.                                                                                                                        |
+| AS_alive_response     | Single | AS $\Rightarrow$ PAMS | Acknowledges the AS_alive_request                                                                                                                                                                      |
+
+### **13.3.6 Flow diagrams AS $\Leftrightarrow$ Injector**
+
+The flow diagrams between an automation system and the injector are the same as for the non-PAMS system described in clause 13.2.10.
+
+### **13.3.7 Flow diagrams AS $\Leftrightarrow$ PAMS**
+
+Figure 13-16 shows how the initialization of a TCP/IP two-way connection is set up. The client (automation system) must first establish a socket to the server (PAMS). Then, the config\_request() message is sent to establish the socket connection.
+
+![Sequence diagram showing the initialization flow between AS (Client) and PAMS (Server) over TCP/IP. It depicts two socket sessions. In the first session, AS opens a socket, sends config_request, receives config_response, and closes the socket. In the second session, AS opens a socket, receives provisioning_request, sends provisioning_response, and closes the socket. A bracket on the right indicates 'Initialization complete' starting from the end of the first session through the end of the second.](1314748d1fff41b2d57a8ba9e9687c6a_img.jpg)
+
+```
+
+sequenceDiagram
+    participant AS as AS (Client)
+    participant PAMS as PAMS (Server)
+    Note over AS, PAMS: TCP/IP
+    AS->>PAMS: Open a socket
+    AS->>PAMS: config_request
+    PAMS-->>AS: config_response
+    AS->>PAMS: Close the socket
+    Note right of PAMS: Initialization complete
+    AS->>PAMS: Open a socket
+    PAMS-->>AS: provisioning_request
+    AS->>PAMS: provisioning_response
+    AS->>PAMS: Close the socket
+
+```
+
+J.287(14)\_F13-16
+
+Sequence diagram showing the initialization flow between AS (Client) and PAMS (Server) over TCP/IP. It depicts two socket sessions. In the first session, AS opens a socket, sends config\_request, receives config\_response, and closes the socket. In the second session, AS opens a socket, receives provisioning\_request, sends provisioning\_response, and closes the socket. A bracket on the right indicates 'Initialization complete' starting from the end of the first session through the end of the second.
+
+**Figure 13-16 – AS/PAMS flow diagram for initialization**
+
+In a system that is using a permanent connection, the AS\_keep\_alive() message should also be sent. The connection to the PAMS is not closed. This is shown in Figure 13-17.
+
+![Sequence diagram for PAMS two-way initialization of a permanent connection between AS (Client) and PAMS (Server).](5509e6ec160899dd306e462bb6a3643b_img.jpg)
+
+This sequence diagram illustrates the interaction between an AS (Client) and a PAMS (Server) over a TCP/IP connection. The process is divided into two main phases: Initialization and Periodic communication.
+
+- Initialization complete:**
+  - The AS sends an "Open a socket" message to the PAMS.
+  - The AS sends a "config\_request" message to the PAMS.
+  - The PAMS responds with a "config\_response" message.
+  - The AS sends a "Close the socket" message to the PAMS.
+- Periodic communication:**
+  - The AS sends an "Open a socket" message to the PAMS.
+  - The AS sends a "provisioning\_request" message to the PAMS.
+  - The PAMS responds with a "provisioning\_response" message.
+  - The AS sends an "AS\_alive\_request" message to the PAMS.
+  - The PAMS responds with an "AS\_alive\_response" message.
+
+The diagram is labeled J.287(14)\_F13-17.
+
+Sequence diagram for PAMS two-way initialization of a permanent connection between AS (Client) and PAMS (Server).
+
+**Figure 13-17 – PAMS two-way initialization of a permanent connection**
+
+Figures 13-18 and 13-19 show two ways that a failure may be detected as the system reconfigured in response.
+
+Figure 13-18<sup>4</sup> shows the PAMS detecting a failure that may not be apparent to an automation system. The PAMS will send a new configuration to the automation system by sending an updated provisioning\_request.
+
+![Sequence diagram for PAMS detecting an injector failure between AS and PAMS.](d0654bc33a544f31c1cb3e0cd77e0aab_img.jpg)
+
+This sequence diagram shows the interaction between an AS and a PAMS over a TCP/IP connection when a failure is detected by the PAMS.
+
+- The AS sends an "Open a socket" message to the PAMS.
+- The PAMS sends a "provisioning\_request" message to the AS.
+- The AS responds with a "provisioning\_response" message.
+- The AS sends a "Close the socket" message to the PAMS.
+
+The diagram is labeled J.287(14)\_F13-18.
+
+Sequence diagram for PAMS detecting an injector failure between AS and PAMS.
+
+**Figure 13-18 – PAMS detects an injector failure**
+
+Figure 13-19<sup>5</sup> shows the automation system detecting a failure that may not be detected by a PAMS (for example a cable being disconnected). The AS may then request that a new injector be assigned to replace the failed unit. Ultimately, it is the PAMS that determines if there is a replacement device
+
+<sup>4</sup> The OPEN and CLOSE socket actions shown in the figure are not required if the PAMS opens a permanent connection.
+
+<sup>5</sup> The OPEN and CLOSE socket actions shown in the figure are not required if the PAMS opens a permanent connection.
+
+available and will send a provisioning\_request when the replacement injector has been fully provisioned.
+
+![Sequence diagram showing AS detecting an injector failure via PAMS.](856f6b5a43a3ca2bf49b8446412dc6ae_img.jpg)
+
+The diagram illustrates a sequence of interactions between an Automation System (AS) and a PAMS (Packet Management System) over a TCP/IP connection. The sequence is as follows:
+
+- The AS sends a message "Open a socket" to the PAMS.
+- The AS sends a message "fault\_request" to the PAMS.
+- The PAMS responds with a message "fault\_response" to the AS.
+- The AS sends a message "Close the socket" to the PAMS.
+- After some time, the AS sends another message "Open a socket" to the PAMS.
+- The AS sends a message "provisioning\_request" to the PAMS.
+- The PAMS responds with a message "provisioning\_response" to the AS.
+- The AS sends a message "Close the socket" to the PAMS.
+
+The diagram is labeled "J.287(14)\_F13-19" at the bottom right.
+
+Sequence diagram showing AS detecting an injector failure via PAMS.
+
+**Figure 13-19 – AS detects an injector failure**
+
+When the PAMS adds or removes a service from an injector, it uses the provisioning\_request to change the service definition in the automation system. Similarly, if an injector is taken offline or replaced by a new physical device, the provisioning\_request is used to tell the automation system of the new configuration. In both cases, the diagram is essentially the same as that used for changes that result from a device failure, as shown in Figure 13-18.
+
+Figure 13-20 shows what happens when the automation system detects a failure with injector communications, but the PAMS has not detected a failure. The AS is expected to retry to establish a connection with the injector periodically until either it works or the PAMS reprovisions the system. The example shown has the PAMS ignoring the fault\_request sent by the AS. It is assumed that either the AS, the PAMS, or both report the fault to the operator for corrective action. If the AS retries and fails again, it should send another fault\_request to the PAMS. The PAMS can reprovision the system if enough failures occur to the same device.
+
+![Sequence diagram showing Injector, AS, and PAMS interactions. The Injector sends a 'Socket failed' message to the AS. The AS responds with 'Open a socket', 'fault_request', and 'fault_response'. The PAMS then sends 'Close the socket' to the AS. The AS then attempts to open a socket again, sending 'splice_init_request' to the Injector and receiving 'splice_init_response'. The PAMS determines no fault is found, and the AS retry timeout reconnect worked. The diagram is labeled J.287(14)_F13-20.](ec96d99a16edb981eb7defe41a79b57f_img.jpg)
+
+```
+
+sequenceDiagram
+    participant Injector
+    participant AS
+    participant PAMS
+    Note left of AS: TCP/IP
+    Note right of AS: TCP/IP
+    Injector->>AS: Socket failed
+    AS->>PAMS: Open a socket
+    AS->>PAMS: fault_request
+    PAMS->>AS: fault_response
+    AS->>PAMS: Close the socket
+    Note right of PAMS: PAMS determines  
+No fault found
+    Note right of AS: AS retry timeout  
+reconnect worked
+    AS->>Injector: AS tries to open a socket
+    AS->>Injector: splice_init_request
+    Injector->>AS: splice_init_response
+  
+```
+
+J.287(14)\_F13-20
+
+Sequence diagram showing Injector, AS, and PAMS interactions. The Injector sends a 'Socket failed' message to the AS. The AS responds with 'Open a socket', 'fault\_request', and 'fault\_response'. The PAMS then sends 'Close the socket' to the AS. The AS then attempts to open a socket again, sending 'splice\_init\_request' to the Injector and receiving 'splice\_init\_response'. The PAMS determines no fault is found, and the AS retry timeout reconnect worked. The diagram is labeled J.287(14)\_F13-20.
+
+**Figure 13-20 – Injector socket failed and recovered**
+
+# 14 Result codes (normative)
+
+**Table 14-1 – Result codes**
+
+| Result | Result name                                             | Description                                                                                                                                                      | Response message                    |
+|--------|---------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------|
+| 100    | Successful response                                     | This result code shall be sent to indicate that everything is fine, no problems, request handled completely.                                                     | All                                 |
+| 101    | Access denied - injector not authorized for DPI service | This result code shall be sent to indicate that the injector is not provisioned, does not support DPI, or that there are possible license problem (user defined) | init_response                       |
+| 102    | CW index does not have code word                        | This result code shall be sent to indicate that request points to a CW index without a code w                                                                    | general_response or inject_response |
+| 103    | DPI has been de-provisioned                             | This result code may be sent to indicate that the injector has been de-provisioned from DPI service.                                                             | alive_response                      |
+| 104    | DPI not supported                                       | This result code may be sent to indicate that the injector does not support DPI functionality                                                                    | init_response                       |
+| 105    | Duplicate service name                                  | This result code may be sent to indicate that the AS has found an invalid duplicate service name.                                                                | provisioning_response               |
+| 106    | Duplicate service name is OK                            | This result code may be sent to indicate that the AS has found a valid duplicate service name.                                                                   | provisioning_response               |
+
+**Table 14-1 – Result codes**
+
+| <b>Result</b> | <b>Result name</b>                             | <b>Description</b>                                                                                                                                                                             | <b>Response message</b> |
+|---------------|------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------|
+| 107           | Encryption not supported                       | This result code shall be sent to indicate that the injector does not support ITU-T J.181 message encryption                                                                                   | inject_response         |
+| 108           | Illegal shared value of DPI PID index found    | This result code may be sent to indicate that the AS does not understand the DPI PID values as properly shared. Both the PAMS and the AS should produce alarms as a result.                    | provisioning_response   |
+| 109           | Inconsistent value of DPI PID index found      | This result code may be sent to indicate that Duplicate value assigned to two or more DPI_PID_index without shared_PID being non-zero. Both PAMS and the AS should produce alarms as a result. | provisioning_response   |
+| 110           | Injector is already in use                     | This result code shall be sent to indicate that another AS is already connected to this injector.                                                                                              | init_response           |
+| 111           | Injector is not provisioned to service this AS | This result code may be sent to indicate that the injector has not been provisioned to service this particular AS.                                                                             | init_response           |
+| 112           | Injector is not provisioned for DPI            | This result code shall be sent to indicate that the injector at this IP address has not been provisioned for DPI operation (yet). Try again later.                                             | init_response           |
+| 113           | Injector will be replaced                      | This result code may be sent to indicate that the PAMS will replace the injector in the near future.                                                                                           | failure_response        |
+| 114           | Invalid Message Size                           | This result code shall be sent to indicate that the message was not the correct length as determined by this Recommendation.                                                                   | ALL                     |
+| 115           | Invalid Message Syntax                         | This result code shall be sent to indicate that fields defined by this Recommendation are not within the valid range.                                                                          | ALL                     |
+
+**Table 14-1 – Result codes**
+
+| <b>Result</b> | <b>Result name</b>                                        | <b>Description</b>                                                                                                                                                                                                | <b>Response message</b>  |
+|---------------|-----------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------|
+| 116           | Invalid Version                                           | This result code shall be sent to indicate that the automation system and injector are using totally incompatible versions of this API. The DPI system should produce a major alarm.                              | init_response            |
+| 117           | No fault found                                            | This result code may be sent to indicate that the PAMS cannot find a communications fault and will most likely not change injectors.                                                                              | failure_response         |
+| 118           | Service name is missing                                   | This result code may be sent to indicate that the service name is missing.                                                                                                                                        | provisioning_response    |
+| 119           | Shared value of DPI PID index not found                   | This result code may be sent to indicate that the AS knows of a common DPI PID between multiple programs. Not found in provisioning_request message data. Both PAMS and the AS should produce alarms as a result. | provisioning_response    |
+| 120           | Splice request failed – Unknown Failure                   | This result code shall be sent to indicate that the injector failed to insert a cue message                                                                                                                       | inject_complete response |
+| 121           | Splice request is rejected - Bad splice_request parameter | This result code shall be sent to indicate that splice request is rejected because of a bad splice_request parameter.                                                                                             | inject_response          |
+| 122           | Splice request was too late – pre-roll is too small       | This result code shall be sent to indicate that a pre-roll parameter of a splice request is too small (should be greater than 4 seconds).                                                                         | inject_response          |
+| 123           | Time type unsupported                                     | This result code shall be sent to indicate that a value for time_type in the timestamp() is unsupported.                                                                                                          | inject_response          |
+| 124           | Unknown failure                                           | This result code shall be sent to indicate that the injector has experienced a possible software failure or an attempt has been made to use an un-implemented functionality.                                      | All                      |
+| 125           | Unknown opID                                              | This result code shall be sent to indicate that an unknown opID is present in data(). Use the result_extension field to indicate which opID is at fault.                                                          | ALL                      |
+
+**Table 14-1 – Result codes**
+
+| <b>Result</b> | <b>Result name</b>              | <b>Description</b>                                                                                                                  | <b>Response message</b> |
+|---------------|---------------------------------|-------------------------------------------------------------------------------------------------------------------------------------|-------------------------|
+| 126           | Unknown value for DPI_PID_index | This result code shall be sent to indicate that the injector does not know of this value.                                           | ALL                     |
+| 127           | Version mismatch                | The message contains a protocol version number not yet supported by the injector.<br>Message features may not be fully implemented. | ALL                     |
+| 128           | Proxy response                  | This result code shall be sent to indicate that everything is fine, no problems, request handled completely by a proxy device.      | init_response           |
+
+# **Annex A****TCP/IP conveyance**
+
+(This annex forms an integral part of this Recommendation.)
+
+TCP/IP conveyance follows the paradigm of ITU-T J.280 communications between a splicer and a server. In this particular case (see Figure 6-1), the communications are primarily point-to-point messages between an automation system and an injector. There are also ancillary (but important) communications between the digital compression system's provisioning and alarm management system (PAMS) and the automation system.
+
+A number of necessary parameters, such as the assignment of IP addresses, are defined in a manner that is outside the scope of this Recommendation.
+
+The communication between the automation system and the injector is conducted over one TCP/IP socket connection per output channel (injector). Once this API connection is established it remains established until one of the devices terminates the API connection at which time re-initialization is needed to splice again. No multicasting or other broadcast communications mechanisms are to be utilized for messages defined by this Recommendation.
+
+All messages exchanged between the automation system and the injector share a common general format detailed in the message format section (see clause 8). The format divides messages into two classes, "single\_operation" and "multiple\_operation". Most traffic is expected to be of the "single\_operation" class. The "multiple\_operation" class will permit the full support of all ITU-T J.181 functions and it allows for a category of messages of the "User Defined" type. These can also be used as a mechanism for private data messages between the automation system and the splicer that are beyond the scope of this Recommendation.
+
+All request messages require a response from the recipient. Most of the response messages only indicate a result and do not contain any other data. They are needed to ensure the requester that the message was received and interpreted correctly. If there are errors, the message can be resent.
+
+"Heartbeat" messages (alive request/alive response) are also provided to ensure both systems that their partner remains connected, even though no splicing related traffic has been sent for a considerable time. Readers should keep in mind that in many distribution systems there may be as few as a single "avail" an hour.
+
+# Annex B ANSI/TIA/EIA-232-F conveyance
+
+(This annex forms an integral part of this Recommendation.)
+
+Data communications for a "classic" automation system utilized point-to-point EIA-422 or EIA-232 communications which required extra characters to provide message synchronization. Messages in this API which are carried either by TIA/EIA-232-F or TIA/EIA-422-B shall utilize the basic link layer syntax, as defined in clause B.1. The data is carried in a binary form on TIA/EIA-232-F or TIA/EIA-422-B. The link layer is used to convey the information from source to destination reliably.
+
+Messages in this API which are carried in video (analogue or digital) shall also utilize the basic link layer syntax, as defined in clause B.1. The implementation specifics are left to the system manufacturer.
+
+## B.1 The basic link layer syntax
+
+**Table B.1 – serial\_linklayer structure**
+
+| Syntax              | Bytes | Type   |
+|---------------------|-------|--------|
+| serial_linklayer(){ |       |        |
+| start_delimiter     | 1     | uimsbf |
+| message()           | *     |        |
+| message_CRC         | 4     | uimsbf |
+| end_delimiter       | 1     | uimsbf |
+| }                   |       |        |
+
+### B.1.1 Semantics of fields in serial\_linklayer()
+
+**start\_delimiter:** This is used to uniquely identify the start of a message. It shall be the value 0x02 (ASCII STX). This code shall not exist within the body of the message unless preceded by an ESC character (see clause B.2 below).
+
+**message():** This field carries the message as defined in clause 8.2.2 or 8.2.3. The message contents will be modified to include escape codes (ESC) to ensure the uniqueness of the start and end delimiters (see clause B.2 below).
+
+**message\_CRC:** This field carries the MPEG standard 32-bit CRC calculated on the original message bytes. One must ensure that the escape encoding is applied to the CRC after its calculation but before the final transmission of the message.
+
+**end\_delimiter:** This is used to uniquely identify the end of a message. It shall be the value 0x03 (ASCII ETX). This code shall not exist within the body of the message unless proceeded by an ESC character (see clause B.2 below).
+
+### B.1.2 Detailed discussion of message syntax and semantics
+
+As detailed below, the message content must be scanned for occurrences of ESC, STX or ETX characters, and if such are found, they are replaced by the escape sequence detailed below.
+
+The escape sequence is used to ensure unique start and end delimiters. By making the start and end unique, the system can reliably synchronize on the start of a message, as well as reliably locate the CRC and the completion of the message.
+
+## **B.2 The escape sequence**
+
+The basic escape code shall be the ASCII escape character 'ESC' (0x1B).
+
+In the "message" and the CRC, all instances of the reserved binary values (STX, ETX and ESC) will be replaced by the escape sequence (<ESC, STX>, <ESC, ETX> and <ESC, ESC> respectively).
+
+On the transmitter, the escape codes are added immediately before the start and end delimiters are added, but after the CRC is calculated and added to the message.
+
+The general rule on the receiver is that any instance of the ESC character is removed on reception and the character immediately following is retained but is not used in checking for synchronization. The CRC is checked after the ESC characters have been removed and the original message has been recreated.
+
+# **Annex C****Digital video system conveyance**
+
+(This annex forms an integral part of this Recommendation.)
+
+For certain specific system architectures, the ability to embed the requests in the vertical ancillary data areas (VANC) of a serial digital video signal is required. SMPTE has standardized the conveyance of the messages defined in this Recommendation in [SMPTE ST 2010].
+
+This method is supported by this Recommendation with some important limitations. The receiving injector must process the message and not replicate a digitized copy of the line(s) that carried it. If a vertical interval is being carried in the compressed stream, the line(s) must be replaced by black or not coded in the MPEG domain. Messages in VANC should be removed.
+
+# **Annex D****Analogue video system conveyance**
+
+(This annex forms an integral part of this Recommendation.)
+
+For certain specific system architectures, the ability to embed the requests in the vertical blanking interval of an analogue video signal is required. This method is supported by this Recommendation with some important limitations.
+
+The receiving injector must process the message and not replicate a digitized copy of the line(s) that carried it. If a vertical interval is being carried in the compressed stream, the line(s) must be replaced by black or not coded in the MPEG domain.
+
+For analogue signals, the transmission system signal-to-noise ratio must be sufficient to permit the CRC or Hamming-code recovery of corrupted characters in the message. Transmission of the message multiple times will help with this, but the users must take care to ensure high quality transmission links.
+
+The data may need to be coded using the escape sequence defined in clause B.2 to ensure proper parsing upon receipt.
+
+It is the implementer's responsibility to ensure that these details, along with many others not within the scope of this Recommendation, are defined before a compliant system can be constructed.
+
+# Bibliography
+
+- [b-ITU-T X.200] Recommendation ITU-T X.200 (1994), *Information Technology – Open Systems Interconnection – Basic Reference Model: The basic model.*
+- [ITU-R BT.653-3] Recommendation ITU-R BT.653-3 (1998), *Teletext systems.*
+- [b-ANSI/SCTE 67] ANSI/SCTE 67 (2010), *Digital Program Insertion Cueing Message for Cable – Interpretation for SCTE 35.*
+- [b-ANSI/TIA/EIA-232-F] ANSI/TIA/EIA-232-F (1997), *Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange.*  
+<<http://standards.globalspec.com/standards/detail?docid=1619487&familyid=JSPBFBAAAAAAA>>
+- [b-ANSI/EIA/TIA-250-C] ANSI/EIA/TIA-250-C (1989), *Electrical Performance for Television Transmission Systems.*  
+<<http://standards.globalspec.com/standards/detail?docid=1575525&familyid=ZACRHAAAAAA>>
+- [b-ATSC A/57B] ATSC A/57B (2008), *Content Identification and Labeling for ATSC transport, Revision B.*
+- [b-ATSC A/52:2010] ATSC A/52 (2010), *Digital Audio Compression Standard (AC-3, E-AC-3).*
+- [CEA 516] CEA-516 (R2008), *North American Basic Teletext Specification (NABTS).*
+- [ETSI ETS 300 706] ETSI ETS 300 706 (2003), *Enhanced Teletext specification.*
+- [ETSI ETS 300 708] ETSI ETS 300 708 (2003), *Television systems; Data transmission within Teletext.*
+- [b-ETSI TR 101 233] ETSI TR 101 233 (1998), *Code of practice for allocation of services in the Vertical Blanking Interval (VBI).*
+- [b-IETF RFC 793] IETF RFC 793 (1981), *Transmission Control Protocol.*
+- [b-IETF RFC 1305] IETF RFC 1305 (1992), *Network Time Protocol (Version 3), Specification, Implementation and Analysis.*
+- [b-IETF RFC 1661] IETF RFC 1661 (1994), *The Point-to-Point Protocol (PPP).*
+- [b-IETF RFC 2728] IETF RFC 2728 (1999), *The Transmission of IP Over the Vertical Blanking Interval of a Television Signal.*
+- [b-ISO/IEC 11172-3] ISO/IEC 11172-3 (1993), *Information Technology – Coding of moving pictures and associated audio for digital storage media at up to about 1.5 Mbit/s, Part 3: Audio.*
+- [b-SMPTE EG 40] SMPTE EG 40 (2002), *Conversion of Time Values Between SMPTE 12M Time Code, MPEG-2 PCR Time Base and Absolute Time.*
+- [b-SMPTE RP 168] SMPTE RP 168 (2009), *Definition of Vertical Interval Switching Point for Synchronous Video Switching.*
+- [b-SMPTE ST 12-1] SMPTE ST 12-1 (2008), *Time and Control Code.*
+- [b-SMPTE ST 259] SMPTE ST 259 (2008), *For Television — SDTV<sup>1</sup> Digital Signal/Data — Serial Digital Interface..*
+- [SMPTE ST 291] SMPTE ST 291 (2011), *Ancillary Data Packet and Space Formatting.*
+
+- [b-SMPTE ST 292-1] SMPTE ST 292-1 (2012), *1.5 Gb/s Signal/Data Serial Interface.*
+- [b-SMPTE ST 298] SMPTE ST 298 (2009), *Universal Labels for Unique Identification of Digital Data.*
+- [b-SMPTE ST 312] SMPTE ST 312 (2001), *Splice Points for MPEG-2 Transport Streams.*
+- [b-SMPTE ST 330] SMPTE ST 330 (2004), *Unique Material Identifier (UMID).*
+- [SMPTE ST 334-1] SMPTE ST 334-1 (2007), *Vertical Ancillary Data Mapping of Caption Data and Other Related Data.*
+
+# 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.295**
+
+(01/2012)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Cable modems
+
+# --- **Functional requirements for a hybrid cable set-top box**
+
+Recommendation ITU-T J.295
+
+
+
+# Recommendation ITU-T J.295
+
+# Functional requirements for a hybrid cable set-top box
+
+## Summary
+
+Recommendation ITU-T J.295 defines the functional requirements of a hybrid cable set-top box. The hybrid cable set-top box is equipped with reception functionalities for broadcasting services, as well as functionalities for IP-based interactive services. In addition, the hybrid cable set-top box supports many up-to-date functions to enable cable television operators to provide advanced services. Examples of primary functions are as a portal screen, as application software plug-ins, and as an interface device capability between cable television access networks and an in-home network.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group |
+|---------|----------------|------------|-------------|
+| 1.0     | ITU-T J.295    | 2012-01-13 | 9           |
+
+## 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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    | Terms and definitions .....                                        | 2  |
+| 3.1  | Terms defined elsewhere .....                                      | 2  |
+| 3.2  | Terms defined in this Recommendation.....                          | 2  |
+| 4    | Abbreviations and acronyms .....                                   | 4  |
+| 5    | Conventions .....                                                  | 5  |
+| 6    | General requirements.....                                          | 5  |
+| 6.1  | Services provided .....                                            | 6  |
+| 6.2  | Assumed cable network.....                                         | 6  |
+| 6.3  | Cross platform .....                                               | 7  |
+| 6.4  | Open software.....                                                 | 7  |
+| 6.5  | Multi-tasking support .....                                        | 7  |
+| 6.6  | CPU architectures.....                                             | 7  |
+| 6.7  | Security.....                                                      | 7  |
+| 6.8  | Adaptation for technical evolution and compatibility .....         | 7  |
+| 6.9  | Service enhancement .....                                          | 7  |
+| 6.10 | User interface (UI).....                                           | 7  |
+| 6.11 | Cable portal .....                                                 | 7  |
+| 6.12 | Content protection .....                                           | 7  |
+| 6.13 | Home network connections .....                                     | 8  |
+| 7    | Service requirements .....                                         | 8  |
+| 7.1  | General .....                                                      | 8  |
+| 7.2  | Requirements for content reception.....                            | 8  |
+| 8    | Broadcasting service.....                                          | 10 |
+| 8.1  | Navigation of a broadcasting service .....                         | 10 |
+| 8.2  | Reception of broadcasting content provided by the broadcaster..... | 10 |
+| 8.3  | Programme selection .....                                          | 10 |
+| 8.4  | Conditional access .....                                           | 10 |
+| 8.5  | Schedule recording .....                                           | 11 |
+| 8.6  | Programme recording .....                                          | 11 |
+| 8.7  | Notice of additional broadcast service .....                       | 11 |
+| 9    | IP interactive services.....                                       | 11 |
+| 9.1  | Network connection.....                                            | 11 |
+| 9.2  | Network connection setting.....                                    | 12 |
+| 9.3  | Delivery of IP interactive services .....                          | 12 |
+| 9.4  | Service navigation .....                                           | 13 |
+
+|      | Page                                                        |    |
+|------|-------------------------------------------------------------|----|
+| 9.5  | Multidevice support for IP interactive services.....        | 13 |
+| 9.6  | IP multimedia streaming.....                                | 13 |
+| 9.7  | Content selection .....                                     | 13 |
+| 9.8  | Conditional access for IP interactive services .....        | 13 |
+| 9.9  | Character input for an interactive service.....             | 13 |
+| 9.10 | Communication error and time-out .....                      | 13 |
+| 9.11 | Notice of additional IP interactive services.....           | 13 |
+| 10   | Display functions for a web/interactive service.....        | 14 |
+| 10.1 | Web browsing.....                                           | 14 |
+| 10.2 | Reception of broadcasting and IP interactive services ..... | 14 |
+| 10.3 | Cable portal .....                                          | 14 |
+| 10.4 | Customization of the cable portal.....                      | 14 |
+| 11   | RCU functions .....                                         | 14 |
+| 11.1 | Conventional remote .....                                   | 14 |
+| 11.2 | Connection method for RCU.....                              | 14 |
+| 11.3 | HN type RCU .....                                           | 15 |
+| 11.4 | Personalization of an HN type RCU screen .....              | 15 |
+| 11.5 | Update of HN type RCU software.....                         | 15 |
+| 11.6 | Internet type RCU.....                                      | 15 |
+| 12   | User interface (UI).....                                    | 15 |
+| 12.1 | General requirements for UI.....                            | 15 |
+| 12.2 | Broadcasting content presentation on the UI.....            | 15 |
+| 13   | Connection interface .....                                  | 15 |
+| 13.1 | Coaxial cable interface .....                               | 15 |
+| 13.2 | Wireless LAN (Wi-Fi) interface.....                         | 16 |
+| 13.3 | WAN interface.....                                          | 16 |
+| 13.4 | Wired LAN interface .....                                   | 16 |
+| 13.5 | Peripheral device interface .....                           | 16 |
+| 13.6 | RCU interface.....                                          | 16 |
+| 13.7 | Output interface .....                                      | 16 |
+| 13.8 | CA card interface.....                                      | 16 |
+| 14   | Authentication and authorization.....                       | 16 |
+| 14.1 | Device authentication and authorization .....               | 17 |
+| 14.2 | User authentication .....                                   | 17 |
+| 14.3 | Authorization of application execution .....                | 17 |
+| 15   | Hybrid broadcasting and web services .....                  | 17 |
+| 15.1 | Cable portal screen .....                                   | 17 |
+| 15.2 | Broadcasting content .....                                  | 18 |
+
+|                                                                                                 | Page |
+|-------------------------------------------------------------------------------------------------|------|
+| 15.3 Simultaneous display of IP interactive services and broadcasting content .....             | 18   |
+| 15.4 Overlaying information on the broadcasting content .....                                   | 18   |
+| 15.5 Services associated with EPG .....                                                         | 18   |
+| 16 Download function for system software/firmware update .....                                  | 18   |
+| 16.1 Download methods for system software/firmware.....                                         | 18   |
+| 16.2 Process in case of download failure .....                                                  | 19   |
+| 16.3 Scheduling of download and report of result .....                                          | 19   |
+| 16.4 Indication of system software/firmware version .....                                       | 19   |
+| 17 Download function for application software .....                                             | 19   |
+| 17.1 Operator initiated application download method .....                                       | 19   |
+| 17.2 User initiated application download method.....                                            | 19   |
+| 17.3 Indication of application software version .....                                           | 19   |
+| 17.4 Subscriber authentication and authorization for pay application software<br>download ..... | 20   |
+| 18 Home network connection.....                                                                 | 20   |
+| 18.1 Transport for HN .....                                                                     | 20   |
+| 18.2 Routing function.....                                                                      | 20   |
+| 18.3 Protocols.....                                                                             | 20   |
+| 19 Management functions.....                                                                    | 20   |
+| 19.1 Provisioning function .....                                                                | 20   |
+| 19.2 STB remote management .....                                                                | 20   |
+| 19.3 Management of subscriber information.....                                                  | 21   |
+| 19.4 Monitoring of reception quality.....                                                       | 21   |
+| 20 Power saving.....                                                                            | 21   |
+| 21 Mechanical requirements.....                                                                 | 21   |
+| Appendix I – Cable network and service delivery .....                                           | 22   |
+| I.1 Cable network architecture.....                                                             | 22   |
+| I.2 Type of service delivery .....                                                              | 22   |
+| Appendix II – Use case .....                                                                    | 24   |
+| II.1 Use case 1: seamless multi-device TV watching experience .....                             | 24   |
+| II.2 Use case 2: social media-assisted TV watching .....                                        | 25   |
+| II.3 Use case 3: livelihood support service .....                                               | 25   |
+| II.4 Use case 4: recommendation service.....                                                    | 26   |
+| Bibliography.....                                                                               | 28   |
+
+
+
+# Recommendation ITU-T J.295
+
+# Functional requirements for a hybrid cable set-top box
+
+# 1 Scope
+
+Recommendation ITU-T J.295 defines the functional requirements of a hybrid cable set-top box (STB) to enable cable television operators to provide advanced services to their subscribers. The hybrid cable set-top box is intended to apply to the services provided by cable television operators, where many types of access network technologies have been recently introduced, e.g., HFC, PON, RFoG. Cable television operators have the capability to provide both broadcasting and interactivity over its own network which was originally intended to distribute broadcasting television programmes, and the hybrid cable set-top box is a core device for the delivery of attractive advanced services.
+
+Functionalities to be implemented in the head-end systems of cable television operators are outside the scope of this Recommendation.
+
+The hybrid cable set-top box is primarily equipped with reception functionalities for broadcasting services and IP-based interactive services. In addition, the STB performs as an interface device between cable television access networks and in-home network devices by being equipped with wireless LAN and IP routing capabilities.
+
+In this Recommendation, portal screen support and application software plug-ins capability are also required by the STB to allow cable television operators to provide various types of services to their subscribers not only from their own service delivery platforms but also from other third-party platforms interconnected with cable operators' platforms.
+
+## 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 J.190] Recommendation ITU-T J.190 (2007), *Architecture of MediaHomeNet*.
+- [ITU-T J.205] Recommendation ITU-T J.205 (2012), *Requirements for an application control framework using integrated broadcast and broadband digital television*.
+- [ITU-T J.218] Recommendation ITU-T J.218 (2007), *Cable modem IPv4 and IPv6 eRouter specification*.
+- [ITU-T J.700] Recommendation ITU-T J.700 (2007), *IPTV service requirements and framework for secondary distribution*.
+- [ITU-T J.701] Recommendation ITU-T J.701 (2008), *Broadcast-centric IPTV terminal middleware*.
+- [ITU-T F.790] Recommendation ITU-T F.790 (2007), *Telecommunications accessibility guidelines for older persons and persons with disabilities*.
+- [ITU-T H.222.0] Recommendation ITU-T H.222.0 (2006) | ISO/IEC 13818-1:2007, *Information technology – Generic coding of moving pictures and associated audio information: Systems*.
+
+[ITU-T Y.1901] Recommendation ITU-T Y.1901 (2009), *Requirements for the support of IPTV services*.
+
+[BBF TR-069] Broadband Forum TR-069 (2007), *CPE WAN Management Protocol v1.1*.
+
+## 3 Terms and definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 integrated broadcast and broadband DTV service** [ITU-T J.205]: A service that simultaneously provides an integrated experience of broadcasting and interactivity relating to media content, data and applications from multiple sources, where the interactivity is sometimes associated with broadcasting programmes.
+
+**3.1.2 cable integrated broadcast and broadband DTV service** [ITU-T J.205]: An integrated broadcast and broadband DTV service managed by cable operators.
+
+### 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 cable platform**: This refers to the entire provision infrastructure of the cable business, including the service delivery platform (SDP), cable network, hybrid cable set-top box, home network and others.
+
+**3.2.2 cable television operator**: A service provider and/or network provider providing television programmes and other interactive services, via a cable television network with radio frequency (RF) signals through coaxial cables or digital light pulses through fixed optical fibres.
+
+**3.2.3 cloud terminal**: A terminal that has at least a client function, browser and Internet connectivity for cloud network connection.
+
+**3.2.4 content**: Information content transmitted via various media through the communication network, including the broadcasting network and IP.
+
+**3.2.5 cross platform**: A coordination service between platforms.
+
+**3.2.6 digital rights management (DRM)**: Digital rights management is for the protection of digital content.
+
+NOTE – In these requirements, use within a home network is assumed.
+
+**3.2.7 home network**: A network within a home compliant with Recommendation ITU-T J.190, consisting of IP-based transport including a wired LAN (Ethernet: IEEE 802.3) and wireless LAN (WiFi: IEEE 802.11a/b/g/n) and non-IP-based communication methods such as ZigBee (IEEE 802.15.4), where the hybrid cable set-top box is equipped with all of the HA, HB, HC and HD functionalities defined in Recommendation ITU-T J.190
+
+**3.2.8 home network (HN) type remote control unit (RCU)**: An RCU connected to the set-top box via an IP home network. Interactive operation is supported. In addition to communicating and controlling the set-top box, the HN type RCU can also access directly services provided by cable operators or other content and/or service providers.
+
+**3.2.9 hybrid cable set-top box (STB)**: An STB that satisfies the requirements defined in this Recommendation. Unless specifically noted, STB shall mean the hybrid cable STB in this Recommendation.
+
+**3.2.10 Internet type remote control unit (RCU):** A terminal with RCU functionalities that allow users to control the set-top box from a remote location via the Internet, e.g., remote setting of schedule recording. This type of RCU may be mobile phones (smart phones, feature phones, etc.), tablet devices, PCs, etc. In addition to communicating and controlling the set-top box, the Internet type RCU can also access directly services provided by cable operators or other content and/or service providers.
+
+**3.2.11 infrared rays (IR) type RCU:** An RCU operating on infrared rays. Only uni-directional operation is supported.
+
+**3.2.12 IP interactive service:** A type of service provided by the cable operator or service provider where the subscriber requests and/or responds to services.
+
+**3.2.13 multichannel video distribution:** A digital television distribution service over cable networks that provides a wide range of multichannel television programmes to subscribers.
+
+**3.2.14 multi-task:** A simultaneous process of live viewing or playback and one or multiple recordings of broadcasting content; the viewing of IP streaming content; and other applications such as games.
+
+**3.2.15 network:** A wired or wireless communication network for the provision of broadcasting and communication services. In this Recommendation, this shall include the in-house communications network, in addition to the access network operated by the cable operator.
+
+**3.2.16 operator:** The cable TV service operator.
+
+**3.2.17 personal information:** Recorded information about an identifiable individual.
+
+NOTE – This may include (1) name, address, email address, (2) race, nationality, ethnicity, origin, colour, religious or political beliefs or associations, (3) age, sex, sexual orientation, marital status, family status, (4) identifying number, code, symbol, (5) finger prints, blood type, inherited characteristics, (6) health care history including information on physical/mental disability, (7) educational, financial, criminal, employment history, (8) others' opinion about the individual, and (9) personal views except those about other individuals.
+
+**3.2.18 plug-in:** Software for displaying, installed independently from the browser.
+
+**3.2.19 provisioning:** Automated initial setting activity.
+
+**3.2.20 radio frequency (RF) type remote control unit (RCU):** An RCU using wireless technology such as RF4CE.
+
+**3.2.21 second screen:** This refers to a display screen of mobile phones or other network-enabled devices that show services associated with the television screen.
+
+**3.2.22 social television:** This is a general term for technology that supports communication and social interaction in either the context of watching television, or related to TV content. It includes the study of television-related social behaviour, devices and networks. Social television systems can for example integrate voice communication, text chat, presence and context awareness, TV recommendations, ratings, or video-conferencing with the TV content, either directly on the screen or by using ancillary devices
+
+**3.2.23 subscriber:** The registered subscriber (representative) to the cable TV service; shall include all persons in the household.
+
+**3.2.24 target advertising:** An advertising service from the operator that targets an individual, a viewer segment, specific markets, specific areas, or facilities, etc.
+
+**3.2.25 terminal:** Equipment consisting of hardware and software with communication means, and equipped with a user interface to enable the user to connect to the network.
+
+**3.2.26 transcoder:** An image conversion process to convert images to match the display capability of the terminal.
+
+**3.2.27 user:** The user of a device connected to a set-top box and a home network. This refers not only to human beings, but may also include logical elements for the communication and usage of applications between devices.
+
+**3.2.28 user interface (UI):** The basic UI is provided by the operating system and defines the display format of information to the user and the data input and operation methods by the user. These requirements assume the use of both character based UIs (CUI) and graphics based UIs (GUI).
+
+**3.2.29 viewer:** A subscriber who is receiving video, audio and/or other information services.
+
+## **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|        |                                                |
+|--------|------------------------------------------------|
+| API    | Application Program Interface                  |
+| CAS    | Conditional Access System                      |
+| CPE    | Customer Premises Equipment                    |
+| CPU    | Central Processing Unit                        |
+| DHCP   | Dynamic Host Configuration Protocol            |
+| DOCSIS | Data Over Cable System Interface Specification |
+| DTCP   | Digital Transmission Content Protection        |
+| EPG    | Electronic Programme Guide                     |
+| FEC    | Forward Error Correction                       |
+| FTTH   | Fibre To The Home                              |
+| HFC    | Hybrid Fibre/Coax                              |
+| HN     | Home Network                                   |
+| H-STB  | Hybrid Set-top box                             |
+| HTML   | Hypertext Markup Language                      |
+| IP     | Internet Protocol                              |
+| LAN    | Local Area Network                             |
+| MIB    | Management Information Base                    |
+| MVPD   | Multichannel Video Programming Distributor     |
+| OS     | Operating System                               |
+| PCM    | Pulse Code Modulation                          |
+| PPV    | Pay Per View                                   |
+| QoS    | Quality of Service                             |
+| RCU    | Remote Control Unit                            |
+| RF     | Radio Frequency                                |
+| SDK    | Software Development Kit                       |
+| SDP    | Service Delivery Platform                      |
+| SNMP   | Simple Network Management Protocol             |
+
+|      |                         |
+|------|-------------------------|
+| SNS  | Social Network Service  |
+| STB  | Set-top box             |
+| UI   | User Interface          |
+| UPnP | Universal Plug and Play |
+| VOD  | Video On Demand         |
+| WAN  | Wide Area Network       |
+
+## 5 Conventions
+
+In this Recommendation:
+
+The phrase "**is required to**" indicates a requirement which must be strictly followed and from which no deviation is permitted if conformity with this document is to be claimed.
+
+The phrase "**is recommended**" indicates a requirement which is recommended but which is not absolutely required. Thus this requirement needs not be present to claim conformity.
+
+The phrase "**is prohibited from**" indicates a requirement which must be strictly followed and from which no deviation is permitted if conformity with this document is to be claimed.
+
+The phrase "**can optionally**" indicates an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformity with this Recommendation.
+
+In the body of this document and its annexes, the words *shall*, *shall not*, *should*, and *may* sometimes appear, in which case they are to be interpreted, respectively, as *is required to*, *is prohibited from*, *is recommended*, and *can optionally*. The appearance of such phrases or keywords in an appendix or in material explicitly marked as *informative* are to be interpreted as having no normative intent.
+
+# 6 General requirements
+
+Figure 6-1 illustrates overall cable architecture which consists of a service delivery platform, a cable network, mobile network, home network and the hybrid cable STB as a core device for advanced cable services. Figure 6-1 also shows some service aspects and the collaboration of applications based on this architecture.
+
+![Figure 6-1: Overall cable architecture supported by the hybrid cable STB. The diagram illustrates a central 'Hybrid cable set-top box' connected to various external and internal components. Externally, it connects to the 'Internet' (via a globe icon), a 'Cable operator' (via a satellite dish icon), and a 'Mobile network' (via a smartphone/tablet icon). The 'Cable operator' is linked to a 'Service delivery platform (SDP)' cloud containing modules for 'App', 'Content', 'Meta data', 'Recommendation', 'ID management', 'Content search', and 'Accounting'. The 'Hybrid cable set-top box' is also connected to a 'Next generation portal' and 'Internet video Internet radio'. Internally, it connects to a 'Home network' via 'Wi-Fi', which includes a 'NAS', 'Multi room DVR', and a 'Remote UI (2nd screen)'. The 'Hybrid cable set-top box' is shown interacting with 'Smart-phone, tablet' devices through 'Multi-device collaboration applications', 'HTML5, open application', and 'Common applications'. Other labels include 'Content related widget', 'Target AD', and 'Content sharing'. A small code 'J.295(12)_F5-1' is visible in the bottom right of the diagram area.](4801720824e4b5e2361a5564f91cfb70_img.jpg)
+
+Figure 6-1: Overall cable architecture supported by the hybrid cable STB. The diagram illustrates a central 'Hybrid cable set-top box' connected to various external and internal components. Externally, it connects to the 'Internet' (via a globe icon), a 'Cable operator' (via a satellite dish icon), and a 'Mobile network' (via a smartphone/tablet icon). The 'Cable operator' is linked to a 'Service delivery platform (SDP)' cloud containing modules for 'App', 'Content', 'Meta data', 'Recommendation', 'ID management', 'Content search', and 'Accounting'. The 'Hybrid cable set-top box' is also connected to a 'Next generation portal' and 'Internet video Internet radio'. Internally, it connects to a 'Home network' via 'Wi-Fi', which includes a 'NAS', 'Multi room DVR', and a 'Remote UI (2nd screen)'. The 'Hybrid cable set-top box' is shown interacting with 'Smart-phone, tablet' devices through 'Multi-device collaboration applications', 'HTML5, open application', and 'Common applications'. Other labels include 'Content related widget', 'Target AD', and 'Content sharing'. A small code 'J.295(12)\_F5-1' is visible in the bottom right of the diagram area.
+
+**Figure 6-1 – Overall cable architecture supported by the hybrid cable STB**
+
+The hybrid cable STB assumes the following conditions in the actual deployment stage.
+
+### 6.1 Services provided
+
+The hybrid cable STB is required to support cable integrated broadcast and broadband DTV services.
+
+The STB is required to receive terrestrial and satellite broadcasting re-transmitted (by trans-modulation) over an RF (not over IP) on the cable access network. The STB is required to receive RF-based multichannel video programmes and can optionally support IP-based ones. The STB is also required to support interactivity such as VOD, voice over IP, TV telephony and electronic commerce.
+
+### 6.2 Assumed cable network
+
+The network where the hybrid cable STB is to be used shall be the fibre to the home (FTTH), hybrid fibre/coax (HFC) or interactive coaxial network, which is currently provided by cable operators. The network is required to be a content delivery network managed by the cable operator. The network assumes interoperability with the networks provided by other operators (broadcasting networks, mobile phone networks, etc.). The network is required to have an Internet connection capability. Furthermore, it is required to connect with the home network inside the subscriber's residence.
+
+### **6.3 Cross platform**
+
+The hybrid cable STB is required to provide services available not only on cable platforms but also on other platforms by coordination between the cable operator and other service providers operating those platforms.
+
+### **6.4 Open software**
+
+The hybrid cable STB is recommended to apply open technologies as much as possible. Attention is drawn to possible IPR implications, e.g., consistency with the ITU-T IPR policy and guidelines. Open-based OS, API, SDK (software development kit), etc. are recommended for the hybrid cable STB.
+
+### **6.5 Multi-tasking support**
+
+The hybrid cable STB is required to support multi-tasking at the CPU kernel level.
+
+### **6.6 CPU architectures**
+
+The hybrid cable STB is required to not depend on any specific type of CPU architecture.
+
+### **6.7 Security**
+
+The hybrid cable STB is required to be equipped with tampering check functions (including tampering prevention functions for the OS, firmware and middleware), application execution permission control, tamper resistance, etc. Enhancement of the CPU internal security is also required to protect it from software hacking by an open OS.
+
+### **6.8 Adaptation for technical evolution and compatibility**
+
+The hybrid cable STB is required to support the cable application framework to ensure backward compatibility and also to support an open platform to prepare for future technical evolution.
+
+### **6.9 Service enhancement**
+
+The hybrid cable STB is required to support service enhancement on the application layer.
+
+### **6.10 User interface (UI)**
+
+The TV screen (first screen) and terminal device screen (second screen) are required to have the capability to support the various implementations of the user interface (UI). The UI is required to provide an intuitive operation for the user with minimum delay of the operation. The UI is required to have the capability to promote advanced services. Personalization and customization of the UI are required to follow the intention of the cable operator. The hybrid cable STB is required to enable subscribers to customize the UI within the permissions given by the cable operator.
+
+### **6.11 Cable portal**
+
+The cable portal is the initial interactive presentation for the subscribers to access various services (TV broadcasting, VOD, web browsing, other interactive services, etc.) provided by the cable operator. It is required to enable the cable operator to customize the cable portal.
+
+### **6.12 Content protection**
+
+It is required for the hybrid cable STB to be equipped with the conventional conditional access system (CAS) to protect broadcasting content. The hybrid cable STB is also required to support a conventional copy protection system already deployed in the cable industry. If content is re-distributed from the STB (e.g., to the home network) after the conditional access has been removed,
+
+the hybrid cable STB is required to apply the content protection method (e.g., DTCP-IP or higher capability) approved by the broadcasting industry.
+
+### **6.13 Home network connections**
+
+The hybrid cable STB is required to support IP network connections in the home network. The hybrid cable STB is required to support both the dynamic host configuration protocol (DHCP) server and client functions, logically. A Digital Living Network Alliance (DLNA) connection is required for video and audio content delivery within the home. The hybrid cable STB can optionally support connections to non-IP devices for various home appliances.
+
+## **7 Service requirements**
+
+### **7.1 General**
+
+#### **7.1.1 Open software, open interface**
+
+The hybrid cable STB is recommended to support open software and open interfaces, especially for OS and middleware.
+
+#### **7.1.2 Compatibility with existing standards**
+
+The hybrid cable STB is required to follow existing domestic and international standards when it is applicable.
+
+#### **7.1.3 Connection to a home terminal device**
+
+The hybrid cable STB is required to support services described in clause 9.3 with home terminal devices connected to the home network.
+
+#### **7.1.4 Backward service compatibility**
+
+The hybrid cable STB is required to support limited functionalities of the software for future platforms without STB platform upgrade. The full functionalities can be realized by STB platform upgrading.
+
+### **7.2 Requirements for content reception**
+
+#### **7.2.1 Simultaneous viewing and recording**
+
+The hybrid cable STB is required to support simultaneously any combination of viewing including content delivery in-home and recording of at least two programmes on the same incoming broadcasting network. It is also required to support the simultaneous viewing of IP streaming content and the recording of a broadcasting programme.
+
+#### **7.2.2 Content quality monitoring**
+
+The hybrid cable STB is recommended to have a quality monitoring function to provide feedback to the cable operator.
+
+#### **7.2.3 Codec requirements**
+
+The hybrid cable STB is required to support the following codecs for broadcasting and interactive services in accordance with the regional broadcasting system requirements.
+
+- Video decoder
+  - Decode MPEG-2 video and MPEG-1 video streams.
+  - Support still-picture decoding on MPEG-1 I-frame.
+  - Decode ITU-T H.264 streams.
+
+- Audio decoder
+  - Decode MPEG-2 audio AAC stream.
+  - Decode MPEG-1/-2 audio layer 2 stream.
+  - Decode AC-3 stream.
+  - Decode DTS stream.
+  - Replay AIFF-C (Audio Interchange File Format – Compression) format, limited to the pulse code modulation (PCM) only.
+  - Support audio mixing method.
+  - Support audio mixing of MPEG-2 AAC and AIFF-C code.
+- Transcoder
+  - Support conversion of codec, bit rate and file format for the above-mentioned codecs is required. Real time conversion is required in the reception of broadcasting content, and the degradation of picture quality shall be minimum. Post conversion for stored content is also required.
+  - At least two simultaneous transcoding is required for the hybrid cable STB.
+  - For post conversion, the hybrid cable STB is required to support the appropriate transcoding scheduling for minimum delay viewing by a smart phone, tablet or PC via the DLNA connection.
+  - De-interlacing conversion is also required.
+- 3D broadcasting support
+  - Support of full HD quality 3D broadcasting is required.
+
+#### **7.2.4 Multiple content reception and its recording**
+
+The hybrid cable STB is required to receive at least two broadcast programmes simultaneously regardless of whether HDD is embedded in the STB or not.
+
+#### **7.2.5 Content selection**
+
+Regardless of the source or type of the content, the hybrid cable STB is required to provide a content selection means so that the subscriber can select content easily and intuitively.
+
+#### **7.2.6 Content sharing**
+
+Regardless of the source or type of content, the hybrid cable STB is required to have the function for content delivery among the terminal devices in the home network in accordance with the policy determined by the stake holders, i.e., cable operator, content originator, etc.
+
+#### **7.2.7 Remote UI**
+
+The hybrid cable STB is required to support a remote UI function on a terminal device connected in the home network or via a public telecommunication network. For example, scheduling a recording from outside the home via the network will be provided by the remote UI.
+
+#### **7.2.8 Social television service**
+
+The hybrid cable STB is required to support social television services such as exchanging social network information, voting for, ranking or comment indication from viewers.
+
+#### **7.2.9 Subscription control**
+
+The hybrid cable STB is required to have a subscription control function where the cable operator may control the delivery of the services based on the subscription status.
+
+#### **7.2.10 Device authentication and subscriber authentication**
+
+The hybrid cable STB is required to support the CAS system for the identification of the CAS module of the STB and/or the subscriber.
+
+## **8 Broadcasting service**
+
+### **8.1 Navigation of a broadcasting service**
+
+The hybrid cable STB is required to navigate broadcasting services via the portal screen on either the first screen or the second screen.
+
+### **8.2 Reception of broadcasting content provided by the broadcaster**
+
+The hybrid cable STB is required to receive television broadcasting content including related data (e.g., EPG) and 3D content.
+
+The hybrid cable STB is required to receive the following services:
+
+- Emergency alert information and special programmes.
+- Multi-view (e.g., several pictures on the same screen).
+- VOD, PPV.
+
+In particular, the hybrid cable STB is required to receive emergency alert information even in its stand-by state, then quickly turn to power-on state automatically, and to process the emergency alert signal. The behaviour for the emergency alert signal is required to be pre-configured by the subscriber.
+
+NOTE – Refer to the download function (clauses 16 and 17) for downloads.
+
+### **8.3 Programme selection**
+
+The hybrid cable STB is required to support the following methods of programme selection using an RCU and other tablet devices:
+
+- Switching broadcasting types (e.g., multichannel video and re-transmission).
+- Input of channel number (e.g., three-digit tuning).
+- Channel up/down.
+- Favourite channel list/short-cut button to favourite channel.
+- EPG.
+- Keyword search (matching of keywords, such as title, cast, genre, etc.).
+- Return to previous programme (previously viewed channel).
+
+It should be noted that the following control options for the programme will be available after programme selection:
+
+- Audio selection (including stereo/mono, main/sub, and language selection).
+- Caption on/off, language selection.
+
+### **8.4 Conditional access**
+
+The hybrid cable STB is required to support the CA module satisfying the requirements defined by the cable operator.
+
+The following provides examples of the functional requirements to the CA module:
+
+- To support the conditional access used in each region.
+- PPV system for each digital broadcast (including viewing history collection).
+
+- Viewing restrictions for each channel using a PIN (PPV).
+- To cope with copy control using an appropriate rights protection method.
+
+### **8.5 Schedule recording**
+
+The hybrid cable STB is required to support schedule recording as follows:
+
+- Support for both schedule recording and reminders.
+- Support for the schedule by date and time, and from the EPG.
+- Support for the checking or deletion of scheduled programmes using the screen.
+- If a scheduled recording has been specified using the EPG, and if the start and/or end time happens to change, the hybrid cable STB is required to perform the schedule recording as per the updated schedule of the programme.
+- A lock function is required to prevent the cancellation of a recording after the recording has started, unless the subscriber specifically intends to cancel the recording. A warning notification is required for such an action.
+
+### **8.6 Programme recording**
+
+The hybrid cable STB is required to record broadcasting content onto a storage device as follows:
+
+- A re-compression function of recorded content is recommended.
+- An intuitive user interface is recommended for recorded content management.
+
+The hybrid cable STB is required to support the following functions when it connects to the external storage device:
+
+- Recording onto the external storage device is only allowed if the functions for content rights protection and copy protection are properly provided.
+- When the external storage devices such as HDD or DVD are connected to the hybrid cable STB through a LAN, it is required to support the DTCP-IP connection.
+- When the hybrid cable STB records the content onto USB connected HDD, only that STB is allowed to playback the stored content. If the STB has been replaced due to machine trouble, it is required to move the stored content from the troubled STB to the new STB with the copy protection linked to the subscriber. USB 2.0 or higher is required.
+- The hybrid cable STB is required to support a copy control function which has been indicated by the original digital copy control information which is embedded in the content, when the STB records the programme onto an external HDD.
+
+### **8.7 Notice of additional broadcast service**
+
+The hybrid cable STB is required to support the functionality to notify subscribers when a broadcasting service has been added (e.g., addition of a community channel).
+
+## **9 IP interactive services**
+
+### **9.1 Network connection**
+
+The hybrid cable STB is required to have a dual-stack function to support both IPv4 and IPv6 as defined in [ITU-T J.218].
+
+### 9.2 Network connection setting
+
+The following setting is required to be configurable:
+
+- LAN communication (wired and wireless LAN, access point, IP address, DNS setting).
+- Cable modem or WAN port (IP address, DNS setting).
+
+Also the following setting is recommended:
+
+- Proxy server (address and port number to be set manually and automatically).
+
+### 9.3 Delivery of IP interactive services
+
+The hybrid cable STB is required to deliver IP interactive services using the browser and/or application download functions. It is recommended to, but not limited to, support the following services:
+
+- IP streaming service
+- IP-based VOD and PPV service
+- IP-based download service
+- Remote access for a scheduled recording manager
+- Multi device service (TV watching on a second screen device, multi-room viewing)
+- Video telephony
+- TV watching enhancement by social media (micro-blog, view ranking, etc.)
+- E-mail service
+- Online municipal or local government information service
+- E-commerce
+- Local information service
+- Targeted advertisements, content recommendations
+- Net supermarket
+- Electronic flyers
+- Online shopping
+- Ticket reservations and purchases
+- News, weather reports, stock market information
+- Remote banking
+- Games, network games
+- Karaoke
+- Internet radio
+
+Additionally the following services can be optionally supported:
+
+- Energy management (real time monitoring, indication, and automatic control of electricity, gas, water, etc.)
+- Interphone connection
+- Home security
+- Infant monitoring, pet monitoring
+- Healthcare
+- Senior person safety monitoring
+- Remote operation of home appliances
+
+### **9.4 Service navigation**
+
+Refer to clause 15.1.
+
+### **9.5 Multidevice support for IP interactive services**
+
+The hybrid cable STB is required to support IP interactive services including multimedia content viewing on a TV display, as well as other terminal devices. It is also required to support necessary copy control to the output signals, in accordance with content rights protection requirements given by content providers.
+
+### **9.6 IP multimedia streaming**
+
+The hybrid cable STB is required to receive unicast signals and recommended to receive multicast signals. As the transmission protocol, RTP/UDP is required, HTTP/TCP is optional. In the cable network, QoS control is required to suppress jitter and packet loss in transmission streaming. The hybrid cable STB is required to absorb the jitter by buffering in accordance with memory capacity, while a clock synchronization mechanism is also required for long term multimedia reception. It is also required to compensate packet loss with FEC.
+
+### **9.7 Content selection**
+
+The hybrid cable STB is required to provide content selection using an RCU and other tablet devices.
+
+### **9.8 Conditional access for IP interactive services**
+
+The hybrid cable STB can optionally support the conditional access to the content delivered by IP. When the STB supports conditional access, it is required to support the following functionalities:
+
+- Conditional access for broadcasting IP streaming
+- On-demand IP streaming
+- Access control on a channel basis or the browser using a password
+- Copy control in accordance with the content rights protection method.
+
+### **9.9 Character input for an interactive service**
+
+The hybrid cable STB is required to support the input of characters using the RCU or the soft keyboard of the HN terminal device defined in [ITU-T J.190].
+
+### **9.10 Communication error and time-out**
+
+The hybrid cable STB is required to notify communication errors and time-outs to the operator. The hybrid cable STB is required to provide a recovery functionality from the communication waiting status. Note that an application on the STB may notify errors to the users including communication problems.
+
+### **9.11 Notice of additional IP interactive services**
+
+The hybrid cable STB is required to support the functionality to notify subscribers when an IP interactive service has been added.
+
+## **10 Display functions for a web/interactive service**
+
+### **10.1 Web browsing**
+
+The hybrid cable STB and/or the second screen device are required to have the capability to display web pages. It is required to have a function to receive the URL input and other information from the search site on the web access screen indicated on the screen through the RCU or the software keyboard displayed on the screen. It is also required to support password control to restrict the direct input of URLs. The hybrid cable STB is required to support the latest version of browsers and protocols.
+
+### **10.2 Reception of broadcasting and IP interactive services**
+
+Either broadcasting services or IP interactive services are required to be selectable through the use of the RCU or icons on the second screen.
+
+### **10.3 Cable portal**
+
+The hybrid cable STB is required to display the cable portal when the STB is turned on or the STB receives an operational command from the RCU. It is required to be selectable by the subscriber and/or operator whether the STB primarily displays the cable portal or not. The appearance of a portal is required to be configurable by the subscriber through the application download.
+
+### **10.4 Customization of the cable portal**
+
+It is required to support the customization of the cable portal by the operator within the range listed in clause 10.3 (by age, generation, etc.) or by the subscriber.
+
+## **11 RCU functions**
+
+The advanced cable STB is required to have the capability to accept controls from the following four types of devices:
+
+- Conventional remote with IR
+- Conventional remote with radio access
+- Second screen terminals on a home network (HN)
+- Tablet and/or smart phone connected to the Internet
+
+The RCU described in this Recommendation is required to provide stress-free operation for subscribers. This clause gives descriptions for each type of RCU.
+
+### **11.1 Conventional remote**
+
+The conventional remote of the hybrid cable STB is required to have the minimum number of buttons for simple operation, by taking advantage of graphical navigation shown on the screen.
+
+### **11.2 Connection method for RCU**
+
+The hybrid cable STB is required to support multiple communication methods for an RCU. Multiple connection support is required for each transmission method.
+
+### **11.3 HN type RCU**
+
+The HN type RCU is required to connect to the STB via the HN and to display the cable portal screen. Through the portal screen, a user can operate the STB with the HN type RCU. In addition, the HN type RCU can access various applications or services provided by cable operators or content providers via the HN. A hardware or software based keyboard and graphical UI including a desktop icon are required for the RCU. It is recommended to implement microphone and voice recognition functions to realize voice input (programme selection, etc.).
+
+### **11.4 Personalization of an HN type RCU screen**
+
+An HN type RCU is required to have the capability to support personalization of the screen in accordance with the preference of subscribers or age groups within the family.
+
+### **11.5 Update of HN type RCU software**
+
+The HN type RCU is required to have the capability of upgrading its functions and application software (refer to clause 16).
+
+### **11.6 Internet type RCU**
+
+The Internet type RCU is required to connect to the STB via the Internet. In addition, the Internet type RCU can access various applications or services provided by cable operators or content providers via the Internet. A hardware or software-based keyboard and graphical UI including a desktop icon are required for the RCU.
+
+## **12 User interface (UI)**
+
+### **12.1 General requirements for UI**
+
+The hybrid cable STB is required to equip the UI with the following requirements:
+
+- 1) Quick response.
+- 2) Intuitive operation:
+  - 2.1) Effortless navigation to new services.
+  - 2.2) Literacy level agnostic operation.
+- 3) State-of-the-art graphical appearance.
+- 4) Telecommunications accessibility for older persons and persons with disabilities [ITU-T F.790].
+
+### **12.2 Broadcasting content presentation on the UI**
+
+The hybrid cable STB is required to allow cable operators to specify the position and the size of broadcasting content presentation on the UI.
+
+The hybrid cable STB is required to have the capability of ensuring that the broadcasting content presentation complies with the technical report [b-EBU-TR 013].
+
+## **13 Connection interface**
+
+### **13.1 Coaxial cable interface**
+
+To provide all the services described in this Recommendation for subscribers, the hybrid cable STB is required to equip a coaxial cable connector as an input terminal. In the hybrid cable STB, an RF tuner receives video signals and the DOCSIS cable modem sends and receives IP packets through this interface.
+
+### **13.2 Wireless LAN (Wi-Fi) interface**
+
+The hybrid cable STB is required to provide wireless LAN (Wi-Fi) functions. It is required to work selectively as an access point or client. The hybrid cable STB is recommended to embed this functionality, but can optionally support this functionality with an external USB Wi-Fi module.
+
+### **13.3 WAN interface**
+
+The hybrid cable STB is required to support an Ethernet WAN interface for non-HFC cable networks, where the embedded cable modem is not used.
+
+### **13.4 Wired LAN interface**
+
+In addition to the wireless LAN (Wi-Fi) interface described in clause 13.2, the hybrid cable STB is required to support wired LAN interface for the same purpose. This interface can also be used for WAN access when the LAN is accessible to the WAN network.
+
+### **13.5 Peripheral device interface**
+
+The hybrid cable STB is required to be equipped with at least two USB terminals for peripheral device support. The STB is required to support the following devices:
+
+- Storage (USB mass storage class)
+- Wi-Fi (USB wireless controller class)
+- Camera (USB video class)
+- Microphone (USB audio class)
+- Hub (USB hub class)
+
+The hybrid cable STB is required to allow applications to utilize these peripherals through the APIs.
+
+### **13.6 RCU interface**
+
+The hybrid cable STB is required to support the four types of RCU interfaces defined in clause 3, i.e., the IR type RCU uses an infrared interface; the RF type RCU uses a wireless interface e.g., RF4CE; the HN type RCU uses a wireless LAN interface e.g., IEEE 802.11n, and the Internet type RCU uses an IP access interface e.g., WAN or wired/wireless LAN. The first three interfaces are used for in-house operation, while the fourth interface is used for STB operation from outside the home.
+
+### **13.7 Output interface**
+
+The hybrid cable STB is required to be equipped with an HDMI interface for HD digital output. The HDMI interface is required to be HDMI 1.4a or higher. The STB is required to support power the on/off control of the external device (e.g., TV set) by HDMI-CEC. The STB is recommended to be equipped with an optical audio interface (IEC 60958). For legacy support, RCA composite with analogue audio (yellow, red, white) are required. The hybrid cable STB is prohibited to include any S terminal, analogue component or IEEE1394 interface.
+
+### **13.8 CA card interface**
+
+The hybrid cable STB is required to be equipped with a CA card interface that complies with the conditional access system used in each region.
+
+## **14 Authentication and authorization**
+
+The hybrid cable STB is required to support authentication and authorization mechanisms of the device and of the user that satisfy the requirements in this clause.
+
+### **14.1 Device authentication and authorization**
+
+The hybrid cable STB is required to support the following device authentication and authorization functions:
+
+- A CA card or downloadable CA is used to authorize broadcasting service reception by the STB.
+- DOCSIS authentication is used to authenticate the STB by the head-end.
+- DTCP-IP is used for device authentication between the hybrid cable STB and other DLNA-capable devices connected to the home network.
+- LLC-HDCP is used for device authentication between the hybrid cable STB and other HDMI devices such as a TV set.
+- The hybrid cable STB is required to support authentication mechanisms to authenticate external devices connected to the home network such as a smart phone or a tablet, where the STB is required to support both types of authentication, i.e., direct authentication between devices (e.g., DLNA remote UI) and authentication via a server (e.g., id and password controlled). After device authentication, authenticated devices will be linked to the STB.
+
+### **14.2 User authentication**
+
+The hybrid cable STB is required to be equipped with the following user authentication functions:
+
+- User authentication using ID and password.
+
+The following authentication methods can optionally be used to provide more advanced services:
+
+- User authentication using image recognition
+- User authentication using voice recognition
+- User authentication using fingerprint recognition
+
+### **14.3 Authorization of application execution**
+
+Considering the situation that subscribers will be able to obtain both applications developed specifically for cable television services and applications available on the open application markets, it is required to define functions that can be accessible only by the privileged applications from the security point of view such as service and content protection. Thus, the hybrid cable STB is required to be equipped with mechanisms to authorize the applications accessible to significant functions including broadcasting-related components.
+
+## **15 Hybrid broadcasting and web services**
+
+### **15.1 Cable portal screen**
+
+The cable portal screen is the initial screen, provided by the cable operator for subscribers to enter TV broadcasting, IP content delivery such as VOD and IP interactive services including web browsing, and hence it is very important for cable television services. The portal screen will also be applicable to various advertising services because it can show banner ads, picture ads, movie ads, etc. It will also provide customization of the portal screen used with personal devices to enable quick service navigation based on viewing history of the subscriber. Refer to clause 10 for the description of display functionalities and browsers.
+
+Although the cable portal screen is supposed to be initially displayed on the TV screen when the hybrid cable STB is turned on, the STB is required to allow the subscriber to choose whether to display the last channel initially or to show the cable portal screen at the time of turn-on of the STB.
+
+The hybrid cable STB is required to support the following installation methods of the cable portal function:
+
+- Pre-installation of the default portal function to the hybrid cable STB before delivery to the user.
+- Automatic download of the cable portal function from the head-end via the IP network after deployment of the STB.
+- Download of the cable portal function as intended by the cable operator's application server.
+
+### **15.2 Broadcasting content**
+
+The hybrid cable STB is required to use the full-screen mode when the STB only shows one broadcast.
+
+### **15.3 Simultaneous display of IP interactive services and broadcasting content**
+
+The hybrid cable STB is required to support the simultaneous display of broadcasting content and IP interactive services which may contain graphic elements such as buttons and icons. The size and position of the broadcasting content may be controlled by the IP interactive services, or by other means to separate their areas to distinguish their own context. However, the STB is required to comply with regulations and/or guidelines for simultaneous display defined by the authorities in each region to the extent defined by such regulations and/or guidelines according to their scope.
+
+### **15.4 Overlaying information on the broadcasting content**
+
+When any information is overlaid on the broadcasting content, the hybrid cable STB is required to comply with regulations and/or guidelines defined by authorities in each region to the extent defined by such regulations and/or guidelines according to their scope.
+
+### **15.5 Services associated with EPG**
+
+The hybrid cable STB is required to support services associated with an EPG. The STB is required to support the application software enabling search and display of related web information based on the attribute information obtained from the EPG.
+
+## **16 Download function for system software/firmware update**
+
+The hybrid cable STB is required to support the following download methods for the system software/firmware update:
+
+- Download via broadcasting RF signals.
+- Download via an IP network, i.e., wired LAN or wireless LAN.
+
+The STB is required to be capable of software download regardless of its power on/off state.
+
+### **16.1 Download methods for system software/firmware**
+
+If the software is downloaded by a broadcasting RF, the hybrid cable STB is required to have the capability to receive the elementary stream service defined in [ITU-T H.222.0] while the STB is in power-off state. The STB is required to support both global head-end insertion and local head-end insertion of the engineering stream. If the STB downloads the software in power-on state, the STB is required to show the warning to the user.
+
+If the system software/firmware is downloaded by an IP, the STB is required to support the download initiated by the cable operator (push download), and software download initiated by the customer support representative at subscriber's premises (pull download). The STB is also required to allow the customer support representative to put software image into the STB from the external storage (USB, etc.). After the system software/firmware update, the STB is required to show the proper notification for the necessary user action (e.g., power-off and on for reboot).
+
+The hybrid cable STB is required to allow the user to choose the behaviour of an operator-initiated download as follows:
+
+- Automatic downloading.
+- Showing notification for downloading each time.
+
+### **16.2 Process in case of download failure**
+
+The hybrid cable STB is required to stop the software update and rollback to the previous version when the software download is not completed normally.
+
+### **16.3 Scheduling of download and report of result**
+
+The hybrid cable STB is required to provide the scheduling of a download and report the result.
+
+It is required to schedule the download and report the result as logs of the STB. It is also required to allow users to see these logs. If the result is abnormal termination, and/or there is an error message with an error code, it is required to include this information in the log.
+
+### **16.4 Indication of system software/firmware version**
+
+The hybrid cable STB is required to allow subscribers to see the device manufacturer ID, model name, model number and software version on the TV screen.
+
+## **17 Download function for application software**
+
+There are two types of download methods for application software. One is the operator-initiated application download which is deployed to the multiple addressing by the cable operator, the other is the user initiated application download which is downloaded from the download server corresponding to the individual subscriber's request.
+
+### **17.1 Operator initiated application download method**
+
+The hybrid cable STB is required to support the automatic download of the application software without the user's awareness. A typical use case of this functionality is for the deployment of new services. After the download of a new service application, the STB is required to provide a notification on the service portal screen.
+
+### **17.2 User initiated application download method**
+
+When a subscriber accesses the application download site and selects the software from the catalogue, the hybrid cable STB is required to download the selected application. The STB is required to support the application with an expiry date and one time application in addition to the normal application. Regarding the download site, the hybrid cable STB is required to support the download from an operator's site, as well as from third party sites.
+
+### **17.3 Indication of application software version**
+
+The hybrid cable STB is required to enable the subscriber to easily confirm the software version on the TV screen.
+
+### **17.4 Subscriber authentication and authorization for pay application software download**
+
+In the case of pay software download, the hybrid cable STB is required to authorize the subscriber by coordination with the cable operator's platform. The subscriber will be authorized based on the individual contract between the cable operator and the subscriber. With the normal completion of the download, the billing process is conducted at the cable operator's platform. The STB is required to support the capability to clearly display billing transaction to the subscriber.
+
+## **18 Home network connection**
+
+The hybrid cable STB is required to support various services using the HN such as content sharing with terminal devices connected to the HN.
+
+### **18.1 Transport for HN**
+
+The hybrid cable STB is required to support wired and wireless IP transport methods, e.g., Ethernet, Wi-Fi (IEEE 802.11a/b/g/n). The STB is recommended to support RF-based transport methods to communicate with non-IP devices within the home, e.g., IEEE 802.15.4 [b-IEEE 802.15.4].
+
+### **18.2 Routing function**
+
+The hybrid cable STB is required to support an IP routing function between WAN and LAN.
+
+### **18.3 Protocols**
+
+The hybrid cable STB is required to support a universal plug and play (UPnP) connection among IP devices in the HN. The latest version of the DLNA standard is required to transfer multimedia within the HN. It is required to adopt the latest version of the DTCP-IP for device authentication and content protection. Proprietary protocols can be used optionally for the transmission of specific information with such devices in the HNs that only support non-IP protocols.
+
+## **19 Management functions**
+
+### **19.1 Provisioning function**
+
+The hybrid cable STB is required to provide a provisioning function in coordination with the head-end system. It is also required to support simple network management protocol (SNMP) and Broadband Forum TR-069 [BBF TR-069].
+
+### **19.2 STB remote management**
+
+The hybrid cable STB is required to enable the cable operator to manage terminal devices remotely in coordination with the head-end system by means of [BBF TR-069]. It is also required to apply SNMP using a cable specific management information base (MIB) to acquire and set parameters for STB specific information for backward compatibility with the existing cable network's management system.
+
+If the STB fails to operate properly, the hybrid cable STB is required to restore to normal operation, as much as possible, from the head-end by means of the [BBF TR-069] reset function.
+
+The STB is required to maintain broadcasting-related services such as watching, recording, scheduled recording regardless of failure, for example, communication function (DOCSIS, Ethernet and WiFi) and application platforms.
+
+### **19.3 Management of subscriber information**
+
+The hybrid cable STB is required to support a gathering function of the subscriber information including viewing history. The STB is also required to protect the collected information. The STB is required to protect transport for sending the collected information to the cable operator. It is also required that personal information can be easily eliminated either by the cable operator or the subscriber.
+
+### **19.4 Monitoring of reception quality**
+
+The hybrid cable STB is required to support a function for monitoring the reception signal quality and reporting the result to the head-end system.
+
+## **20 Power saving**
+
+The hybrid cable STB is recommended to have four power states: Power-on, Function stand-by, Stand-by, and Power-off for energy saving. The STB is required to enable the subscriber to set the power status. In the Function stand-by state, remote scheduled recording and the reception of emergency alert signals shall be supported. EPG information and RCU signal reception are also required in the Stand-by state.
+
+The hybrid cable STB is required to have a power ON/OFF communication function with the TV receiver. The STB is required to allow other external devices to control the power status of the STB via Wi-Fi/LAN within the HN.
+
+## **21 Mechanical requirements**
+
+The hybrid cable STB is recommended to have a mechanical structure for space saving, simple operation and cost reduction. The requirements are listed below:
+
+- External adapter type power source is recommended for space saving.
+- Card slots for conditional access shall be provided.
+- An LED shall be mounted for the indication of the being in operation stage. The hybrid cable STB is required to have at least one LED to indicate its status. The STB is also required to receive signals from an IR type RCU.
+- The meaning, method and colour of the LED shall be left to the manufacturer's product planning.
+- The following switches shall be provided for direct control of the STB Power on/off, hardware reset, channel up/down, selection of broadcast types (e.g., multichannel video reception or re-transmission).
+- The input and output interfaces listed in clause 13 shall be provided.
+- It is recommended to support both vertical and horizontal placement.
+
+# Appendix I
+
+## Cable network and service delivery
+
+(This appendix does not form an integral part of this Recommendation.)
+
+### I.1 Cable network architecture
+
+The cable network architecture including the hybrid cable STB is shown in Figure I.1. It is configured to distribute broadcasting and interactive services to the subscriber through the cable network where the transmission quality is guaranteed. However, if the source of the content is via the Internet, the quality cannot be guaranteed due to the best effort connection.
+
+![Figure I.1 – Cable network architecture diagram](7d2d1d3870cd224c4430d19334557716_img.jpg)
+
+The diagram illustrates the cable network architecture, divided into three main sections: External network, Cable network, and Home network.
+
+- External network:** On the left, various content sources are shown: Digital broadcasting contents (primary) connected to a Broadcasting network; ISP services connected to the Internet; IP contents, EPG services, and Other platforms connected to a Managed IP network; and VOD/PPV contents connected to the Internet.
+- Cable network:** The central part of the diagram. It features a **Cable head-end** which includes three management blocks: **Digital broadcasting system management** (Decryption, Multiplexing, Encryption (secondary)), **VOD/PPV system management**, and **IP services system management** (Streaming, IP telephone, mail, etc.). These are connected to a **CMTS or OLE** block. Above the head-end is an oval labeled **CableSDP** containing five boxes: **Certification**, **Charges**, **Contents**, **Services**, and **Location**. The CMTS or OLE connects to a **Cable delivery network** cloud.
+- Home network:** On the right, the Cable delivery network connects to a **CM or ONU**, which in turn connects to an **STB** (Set-Top Box). The STB is connected to a **TV**, a **Tablet**, and a **Smart-phone terminal**. Additionally, an **MTA** (Media Terminal Adapter) is connected to the STB and a **TEL SET** (Telephone Set).
+
+Figure I.1 – Cable network architecture diagram
+
+J.295(12)\_FI.1
+
+**Figure I.1 – Cable network architecture**
+
+### I.2 Type of service delivery
+
+Figure I.2 shows the type of service delivery using the hybrid cable STB:
+
+- 1) Multichannel, re-transmission of digital broadcasting and VOD/PPV service.
+- 2) Scheduled recording service linked with a mobile device.
+- 3) Distribution of cable content through the mobile communication network to the terminals of cable subscribers (this service bypasses the hybrid cable STB).
+- 4) Distribution of IP services through the Internet.
+- 5) Collaboration services with other platforms.
+
+![Diagram illustrating the types of service delivery. At the top, 'CableSDP' (Certification, Charges, Contents, Services) and 'Other SDP' (Certification, Advertisement, Charges, Contents, Services) are shown. Below them, 'Cable operators' handle 'Multi-channel', 'Retransmission', and 'VOD'. A 'Cable delivery network' connects these to 'STB' and 'TV'. 'Internet' (Video-sharing, Web search, Microblog, Smart TV, Auction) and 'Mobile communications network' (EC, Product sales, Education, Medical care, Game, Guide) also connect to 'Wifi devices'. Numbered arrows (1-5) show the flow of services from SDPs and networks to end devices.](c494cd874a082a97b50b3c4d3938f467_img.jpg)
+
+The diagram illustrates the flow of service delivery from various Service Delivery Platforms (SDPs) and networks to end-user devices. At the top, two SDPs are shown: **CableSDP** (containing Certification, Charges, Contents, Services) and **Other SDP** (containing Certification, Advertisement, Charges, Contents, Services). Below these, **Cable operators** manage **Multi-channel**, **Retransmission**, and **VOD** services. A **Cable delivery network** connects these operators to **STB** (Set-Top Box) and **TV**. The **Internet** (with services like Video-sharing, Web search, Microblog, Smart TV, and Auction) and **Mobile communications network** (with services like EC, Product sales, Education, Medical care, Game, and Guide) also connect to **Wifi devices**. Numbered arrows (1-5) indicate the flow of services: 1. From Cable delivery network to STB; 2. From Mobile to Cable operators; 3. From Other SDP to Wifi devices; 4. From Internet to Wifi devices; 5. From Cable operators to Wifi devices.
+
+Diagram illustrating the types of service delivery. At the top, 'CableSDP' (Certification, Charges, Contents, Services) and 'Other SDP' (Certification, Advertisement, Charges, Contents, Services) are shown. Below them, 'Cable operators' handle 'Multi-channel', 'Retransmission', and 'VOD'. A 'Cable delivery network' connects these to 'STB' and 'TV'. 'Internet' (Video-sharing, Web search, Microblog, Smart TV, Auction) and 'Mobile communications network' (EC, Product sales, Education, Medical care, Game, Guide) also connect to 'Wifi devices'. Numbered arrows (1-5) show the flow of services from SDPs and networks to end devices.
+
+**Figure I.2 – Type of service delivery**
+
+# Appendix II
+
+## Use case
+
+(This appendix does not form an integral part of this Recommendation.)
+
+Expected use cases for a hybrid cable STB are described below.
+
+## II.1 Use case 1: seamless multi-device TV watching experience
+
+This use case means seamless video content delivery without noticing the origin point of content or the delivery method between different devices through the collaboration of a VOD server, set-top box, smart phone and tablet devices in the cloud network.
+
+Let us suppose that a multichannel broadcast content server, streaming server for multi-device on the network side and a set-top box, smart phone and tablet devices in the home network are connected as shown in Figure II.1. If a user's information on viewing time, i.e., content resume point, becomes common in the network, it will be able to resume the content on the screen of a different device seamlessly without noticing the delivery route.
+
+In the case where a user is watching recorded content on a TV screen and then moves to another of the user's rooms to watch the remaining content on the display of a smart phone, the smart phone disseminates a request command to the set-top box. Upon receipt of the command, the set-top box begins trans-coding from the resume point then delivers content to the smart phone, which means a seamless video content delivery service. The resume point is shared in the network as the common information for each part of the content and each user. The content resume service will be available not only in home but also outside through the mobile network in which a streaming video service is available by smart phones or tablet devices. The associated services such as authentication between devices, parental lock, etc. shall be provided as a set of functions of a video delivery server under the viewing situation in which a common set-top box and multiple smart phones exist.
+
+In addition, a collaboration service will be available for audio content which means music programme delivery to the speakers on TV from a smart phone by a DLNA media transition.
+
+![Diagram illustrating the seamless multi-device TV watching experience. A Cable TV station and a Streaming server for multi-device are connected to a central Content resume sharing pointer. The pointer is connected to a Mobile network and a Home network. The Home network contains a TV, a set-top box (STB), and speakers. The Mobile network contains a smartphone and a tablet. Arrows show the flow of content: Multi-channel broadcast from the Cable TV station to the STB; VOD from the Streaming server to the STB; Streaming from the Streaming server to the Mobile network; Streaming from the STB to the Mobile network; and Audio streaming from the Mobile network to the speakers.](1c9a5a80a4ed18fdfda1c8ae915966bf_img.jpg)
+
+The diagram illustrates the seamless multi-device TV watching experience. At the top, a 'Cable TV station' and a 'Streaming server for multi-device' are shown. A green arrow labeled 'Multi-channel broadcast' points from the Cable TV station to a set-top box (STB). A red arrow labeled 'VOD' points from the Streaming server to the STB. Both the Cable TV station and the Streaming server have arrows pointing to a central box labeled 'Content resume sharing pointer'. From this pointer, a red arrow labeled 'Streaming' points into an orange oval representing the 'Mobile network', which contains a smartphone and a tablet. Another red arrow labeled 'Streaming from STB' points from the STB into a blue oval representing the 'Home network', which contains a TV and two speakers. A grey arrow labeled 'Audio streaming' points from the smartphone in the mobile network to the speakers in the home network. The TV, smartphone, and tablet all display the same video content. The text 'J.295(12)\_FII.1' is located in the bottom right corner of the diagram.
+
+Diagram illustrating the seamless multi-device TV watching experience. A Cable TV station and a Streaming server for multi-device are connected to a central Content resume sharing pointer. The pointer is connected to a Mobile network and a Home network. The Home network contains a TV, a set-top box (STB), and speakers. The Mobile network contains a smartphone and a tablet. Arrows show the flow of content: Multi-channel broadcast from the Cable TV station to the STB; VOD from the Streaming server to the STB; Streaming from the Streaming server to the Mobile network; Streaming from the STB to the Mobile network; and Audio streaming from the Mobile network to the speakers.
+
+Figure II.1 – Seamless multi device TV watching experience
+
+### II.2 Use case 2: social media-assisted TV watching
+
+This use case enables value-added services for content viewing, by showing a viewer's real-time impression and reputation regarding current programmes on the screen of a user's device (i.e., tablet device or smart phone) which has authentication-coupling with a set-top box. As shown in Figure II.2, a social media coordination server collects a user's impression and/or tendency of comments regarding a programme from a microblog, blog, social network service (SNS), etc., based on blog topics or hash-tags. In the user's home, a tablet device or smart phone catches the present channel information of the set-top box and gets comments and statistical data from a social media coordination server. During the programme these real-time comments and/or impressions are collected and displayed on the TV screen with statistical data.
+
+Other usage of social media is a text message transaction through a TV screen by sharing information (presence) of a programme that is being watched among the user's friends and family. This service enables a user to recommend the programme to a friend with VOD, while enabling them to share comments when viewing the programme.
+
+![Diagram of social media-assisted TV watching architecture.](b5335262987c819d7f71ce40f99cb71b_img.jpg)
+
+The diagram illustrates the architecture for social media-assisted TV watching. A 'Cable TV station' sends a 'Multi-channel broadcast' to a television set. The TV displays a 'Short message from friends'. Above the TV is a set-top box. A 'Home network' (indicated by a blue oval) contains a 'Smartphone' and a 'Tablet device', with a 'User' icon next to them. A 'Social media coordination server' is connected to the set-top box. The server receives 'Content metadata' from the Cable TV station and 'Collecting impression and reputation on content' from 'Microblog, blog, SNS'. The server sends 'Comments and statistics on the viewed programme' to the smartphone/tablet and 'Channel information about the viewed programme' to the set-top box. The set-top box then sends 'User access' information back to the smartphone/tablet. The diagram is labeled 'J.295(12)\_FII.2'.
+
+Diagram of social media-assisted TV watching architecture.
+
+Figure II.2 – Media assisted TV watching
+
+### II.3 Use case 3: livelihood support service
+
+This use case describes a livelihood support service utilizing the set-top box and cable television network. Figure II.3 shows a remote healthcare service using home healthcare devices. The data from a blood pressure monitor, the bathroom scales (weight) and pedometer are collected in the set-top box through WiFi or a Bluetooth system and presented to the user on a TV screen. At the same time the set-top box delivers the collected data to a hospital, pharmacy and health consultant that relate to the user through the personal data server. Based on the stored data in the server, various services such as health consultancy, remote diagnosis-aid will be available by utilizing a TV telephony system provided by the cable network.
+
+![Diagram of Livelihood support service – healthcare. A central 'Personal data server' cloud is connected to a 'Hospital', 'Pharmacy', and 'Health consultant'. Below the server, a 'Home network' (Wi-Fi, bluetooth) connects various devices (smartphone, tablet, smartwatch, glasses) to a 'Personal data server'. A monitor displays healthcare data (ECG, blood pressure) for 'Collection and analysis of healthcare data' and 'Presenting healthcare data for user and consultation'. The diagram is labeled JJ.295(12)_FII.3.](7ae836e598020d937ed1478c2ef13025_img.jpg)
+
+The diagram illustrates a healthcare livelihood support system. At the top, a cloud labeled 'Personal data server' is connected via double-headed arrows to three external entities: 'Hospital' (represented by a building and ambulance), 'Pharmacy' (represented by a person at a counter), and 'Health consultant' (represented by a person in a white coat). Below the server, a large blue oval labeled 'Home network' contains icons for a smartphone, tablet, smartwatch, and glasses. Arrows point from these devices to the 'Personal data server'. To the left of the home network, a monitor displays a video of a person and a graph of vital signs. Below the monitor is a set-top box. Text labels indicate 'Collection and analysis of healthcare data' (with a green arrow from the server to the monitor) and 'Presenting healthcare data for user and consultation' (pointing to the monitor). The diagram is labeled 'JJ.295(12)\_FII.3' in the bottom right corner.
+
+Diagram of Livelihood support service – healthcare. A central 'Personal data server' cloud is connected to a 'Hospital', 'Pharmacy', and 'Health consultant'. Below the server, a 'Home network' (Wi-Fi, bluetooth) connects various devices (smartphone, tablet, smartwatch, glasses) to a 'Personal data server'. A monitor displays healthcare data (ECG, blood pressure) for 'Collection and analysis of healthcare data' and 'Presenting healthcare data for user and consultation'. The diagram is labeled JJ.295(12)\_FII.3.
+
+**Figure II.3 – Livelihood support service – healthcare**
+
+### II.4 Use case 4: recommendation service
+
+This use case assumes that the cable operator will provide a recommendation service to the subscriber by acquiring and utilizing various pieces of information on the user, to recommend content and goods which are most suited to the subscriber (means personalized recommendation). It is also recommended to deliver the following services without using a subscriber's personal information, where the subscriber does not explicitly indicate the conditions of recommendation.
+
+- Ranking
+- Highly recommended by the shop
+- Goods recommendation linked to viewing history
+- Meta-data related content (director, artist, cast links, etc.)
+- Recommendation by friends
+- Recommendation from other users
+
+Based on the viewing history obtained from the hybrid cable STB which may include a subscriber's tastes, after keyword search and data aggregation by the search engine and weighting by the cable operator's business rules (e.g., delivery of new titles first), the recommendation service is distributed to the subscriber. Figures II.4, II.5 and II.6 show sample screens for content recommendations, and goods recommendations, respectively.
+
+![A diagram of a content recommendation screen layout. At the top is a 'Most popular' section with six red rectangular boxes in a row. Below that, on the left, is a large light blue 'Recommended' box. To its right is an 'Only for you' section with two green boxes stacked vertically. Next is a 'Ranking' section with five small purple boxes in a vertical column. On the far right is a 'From friends' section with five small orange boxes in a vertical column. A small identifier 'J.295(12)_FII.4' is at the bottom right.](24b549c0c4b79c515b244625cf4f4978_img.jpg)
+
+Recommended contents
+
+J.295(12)\_FII.4
+
+A diagram of a content recommendation screen layout. At the top is a 'Most popular' section with six red rectangular boxes in a row. Below that, on the left, is a large light blue 'Recommended' box. To its right is an 'Only for you' section with two green boxes stacked vertically. Next is a 'Ranking' section with five small purple boxes in a vertical column. On the far right is a 'From friends' section with five small orange boxes in a vertical column. A small identifier 'J.295(12)\_FII.4' is at the bottom right.
+
+**Figure II.4 – Sample screen of a content recommendation service**
+
+![A diagram of a book recommendation screen. The top left section is titled 'Recommendations from the viewing history' and contains five grey book icons. Below it is a section titled 'Customers who bought items in your recent history also bought' containing six green book icons. On the right side is a vertical section titled 'Best sellers Books : Top 3' containing three orange book icons numbered 1, 2, and 3. A small identifier 'J.295(12)_FII.5' is at the bottom right.](03498c9b76f980b32f2dfbb7c2e539d2_img.jpg)
+
+Recommended books
+
+J.295(12)\_FII.5
+
+A diagram of a book recommendation screen. The top left section is titled 'Recommendations from the viewing history' and contains five grey book icons. Below it is a section titled 'Customers who bought items in your recent history also bought' containing six green book icons. On the right side is a vertical section titled 'Best sellers Books : Top 3' containing three orange book icons numbered 1, 2, and 3. A small identifier 'J.295(12)\_FII.5' is at the bottom right.
+
+**Figure II.5 – Sample of a goods recommendation screen**
+
+![A diagram of a DVD recommendation screen. It features a grid with four columns: 'New arrival' (orange boxes), 'Soon to arrive' (light blue boxes), 'Ranking' (red boxes), and 'Recommended' (green boxes). Each column has three rows, with each row containing a colored box and a white text area to its right. A small identifier 'J.295(12)_FII.6' is at the bottom right.](9db774ce7e2ae9d89f439a41156214dd_img.jpg)
+
+Recommended DVD videos
+
+Recommendations from the viewing history
+
+J.295(12)\_FII.6
+
+A diagram of a DVD recommendation screen. It features a grid with four columns: 'New arrival' (orange boxes), 'Soon to arrive' (light blue boxes), 'Ranking' (red boxes), and 'Recommended' (green boxes). Each column has three rows, with each row containing a colored box and a white text area to its right. A small identifier 'J.295(12)\_FII.6' is at the bottom right.
+
+**Figure II.6 – Sample of a goods recommendation screen**
+
+# Bibliography
+
+- [b-IEEE 802.15.4] IEEE 802.15.4-2006, *IEEE Standard for Information technology – Telecommunications and information exchange between systems – Local and metropolitan area networks – Specific requirements Part 15.4: Wireless Medium Access Control (MAC) and Physical Layer (PHY) Specifications for Low-Rate Wireless Personal Area Networks (WPANs)*.
+- [b-EBU-TR 013] EBU-TR 013 (2011), *The Future of Terrestrial Broadcasting Version 1.1 (2011)*, EBU Technical Report.
+- [b-JCL SPEC-001] JCL Spec-001, Version 1.01 (2008), *Operational specifications for BS digital satellite broadcasting trans-modulation*.
+- [b-JCL SPEC-003] JCL Spec-003, Version 2.1 (2010), *Operational specifications for re-max digital broadcasting (independent broadcasting)*.
+- [b-JCL SPEC-004] JCL Spec-004, Version 2.1 (2010), *Operational specifications for re-max digital broadcasting (i-HITS)*.
+- [b-JCL SPEC-005] JCL Spec-005, Version 2.2 (2010), *Operational specifications for JC-HITS trans-modulation*.
+- [b-JCL SPEC-006] JCL Spec-006, Version 2.01 (2008), *Operational specifications for digital terrestrial television broadcasting pass through*.
+- [b-JCL SPEC-007] JCL Spec-007, Version 2.01 (2008), *Operational specifications for digital terrestrial television broadcasting trans-modulation*.
+
+
+
+## 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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+
+
+# Recommendation **ITU-T J.298 (06/2024)**
+
+SERIES J: Cable networks and transmission of television,  
+sound programme and other multimedia signals
+
+Cable set-top box
+
+---
+
+**Requirements and technical specifications of a  
+cable TV hybrid set-top box compatible with  
+terrestrial and satellite TV transport**
+
+![ITU logo](0538daaa5583c23e17db3a12f2281a55_img.jpg)
+
+The logo of the International Telecommunication Union (ITU), featuring the letters 'ITU' in blue inside a circle with a globe-like design.
+
+ITU logo
+
+## ITU-T J-SERIES RECOMMENDATIONS **Cable networks and transmission of television, sound programme and other multimedia signals**
+
+|                                                                                                 |                    |
+|-------------------------------------------------------------------------------------------------|--------------------|
+| GENERAL RECOMMENDATIONS                                                                         | J.1-J.9            |
+| GENERAL SPECIFICATIONS FOR ANALOGUE SOUND-PROGRAMME TRANSMISSION                                | J.10-J.19          |
+| PERFORMANCE CHARACTERISTICS OF ANALOGUE SOUND-PROGRAMME CIRCUITS                                | J.20-J.29          |
+| EQUIPMENT AND LINES USED FOR ANALOGUE SOUND-PROGRAMME CIRCUITS                                  | J.30-J.39          |
+| DIGITAL ENCODERS FOR ANALOGUE SOUND-PROGRAMME SIGNALS - PART 1                                  | J.40-J.49          |
+| DIGITAL TRANSMISSION OF SOUND-PROGRAMME SIGNALS                                                 | J.50-J.59          |
+| CIRCUITS FOR ANALOGUE TELEVISION TRANSMISSION                                                   | J.60-J.69          |
+| ANALOGUE TELEVISION TRANSMISSION OVER METALLIC LINES AND INTERCONNECTION WITH RADIO-RELAY LINKS | J.70-J.79          |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS                                                      | J.80-J.89          |
+| ANCILLARY DIGITAL SERVICES FOR TELEVISION TRANSMISSION                                          | J.90-J.99          |
+| OPERATIONAL REQUIREMENTS AND METHODS FOR TELEVISION TRANSMISSION                                | J.100-J.109        |
+| INTERACTIVE SYSTEMS FOR DIGITAL TELEVISION DISTRIBUTION (DOCSIS FIRST AND SECOND GENERATIONS)   | J.110-J.129        |
+| TRANSPORT OF MPEG-2 SIGNALS ON PACKETIZED NETWORKS                                              | J.130-J.139        |
+| MEASUREMENT OF THE QUALITY OF SERVICE - PART 1                                                  | J.140-J.149        |
+| DIGITAL TELEVISION DISTRIBUTION THROUGH LOCAL SUBSCRIBER NETWORKS                               | J.150-J.159        |
+| IPCABLECOM (MGCP-BASED) - PART 1                                                                | J.160-J.179        |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS - PART 1                                             | J.180-J.189        |
+| CABLE MODEMS AND HOME NETWORKING                                                                | J.190-J.199        |
+| APPLICATION FOR INTERACTIVE DIGITAL TELEVISION - PART 1                                         | J.200-J.209        |
+| INTERACTIVE SYSTEMS FOR DIGITAL TELEVISION DISTRIBUTION (DOCSIS THIRD TO FIFTH GENERATIONS)     | J.210-J.229        |
+| MULTI-DEVICE SYSTEMS FOR CABLE TELEVISION                                                       | J.230-J.239        |
+| MEASUREMENT OF THE QUALITY OF SERVICE - PART 2                                                  | J.240-J.249        |
+| DIGITAL TELEVISION DISTRIBUTION THROUGH LOCAL SUBSCRIBER NETWORKS                               | J.250-J.259        |
+| IPCABLECOM (MGCP-BASED) - PART 2                                                                | J.260-J.279        |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS - PART 2                                             | J.280-J.289        |
+| <b>CABLE SET-TOP BOX</b>                                                                        | <b>J.290-J.299</b> |
+| APPLICATION FOR INTERACTIVE DIGITAL TELEVISION - PART 2                                         | J.300-J.309        |
+| MEASUREMENT OF THE QUALITY OF SERVICE - PART 3                                                  | J.340-J.349        |
+| IPCABLECOM2 (SIP-BASED) - PART 1                                                                | J.360-J.379        |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS - PART 3                                             | J.380-J.389        |
+| MEASUREMENT OF THE QUALITY OF SERVICE - PART 4                                                  | J.440-J.449        |
+| IPCABLECOM2 (SIP-BASED) - PART 2                                                                | J.460-J.479        |
+| DIGITAL TRANSMISSION OF TELEVISION SIGNALS - PART 4                                             | J.480-J.489        |
+| TRANSPORT OF LARGE SCREEN DIGITAL IMAGERY                                                       | J.600-J.699        |
+| SECONDARY DISTRIBUTION OF IPTV SERVICES                                                         | J.700-J.799        |
+| MULTIMEDIA OVER IP IN CABLE                                                                     | J.800-J.899        |
+| TRANSMISSION OF 3-D TV SERVICES                                                                 | J.900-J.999        |
+| CONDITIONAL ACCESS AND PROTECTION                                                               | J.1000-J.1099      |
+| SWITCHED DIGITAL VIDEO OVER CABLE NETWORKS                                                      | J.1100-J.1119      |
+| SMART TV OPERATING SYSTEM                                                                       | J.1200-J.1209      |
+| IP VIDEO BROADCAST                                                                              | J.1210-J.1219      |
+| CABLE SET-TOP BOX - PART 2                                                                      | J.1290-J.1299      |
+| CLOUD-BASED CONVERGED MEDIA SERVICES FOR IP AND BROADCAST CABLE TELEVISION                      | J.1300-J.1309      |
+| CLOUD-BASED SERVICES FOR IP DELIVERY OVER INTEGRATED BROADBAND CABLE NETWORK                    | J.1310-J.1319      |
+| TELEVISION TRANSPORT NETWORK AND SYSTEM DEPLOYMENT IN DEVELOPING COUNTRIES                      | J.1400-J.1409      |
+| ARTIFICIAL INTELLIGENCE (AI) ASSISTED CABLE NETWORKS                                            | J.1600-J.1649      |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T J.298
+
+# Requirements and technical specifications of a cable TV hybrid set-top box compatible with terrestrial and satellite TV transport
+
+## Summary
+
+Recommendation ITU-T J.298 describes the requirements and technical specifications of a cable TV hybrid set-top box compatible with terrestrial and satellite TV transport. The main purpose of the Recommendation is to specify minimum and basic requirements for a hybrid set-top box (STB), which meets the requirements of all countries and regions. The hybrid set-top box has full functionalities for traditional cable broadcasting services based on Recommendation ITU-T J.83; at the same time, satellite or terrestrial broadcast receiving functions will also be implemented so that the STB is able to receive satellite or terrestrial broadcasting services. The basic functionalities for IP-based interactive video services are also required so that the STB is able to support the latest Internet protocol (IP) interactive services together with legacy cable and satellite/terrestrial services.
+
+## History \*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T J.298    | 2019-03-22 | 9           | 11.1002/1000/13834 |
+| 2.0     | ITU-T J.298    | 2024-06-29 | 9           | 11.1002/1000/15984 |
+
+## Keywords
+
+Set-top box, television transport.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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 .....                                       | 4  |
+| 3.1  | Terms defined elsewhere .....                           | 4  |
+| 3.2  | Terms defined in this Recommendation.....               | 4  |
+| 4    | Abbreviations and acronyms .....                        | 4  |
+| 5    | Conventions .....                                       | 7  |
+| 6    | Overview .....                                          | 7  |
+| 6.1  | Overview of hybrid video system.....                    | 7  |
+| 6.2  | The hybrid STB software architecture .....              | 9  |
+| 6.3  | The hybrid STB categories .....                         | 10 |
+| 7    | Requirements .....                                      | 11 |
+| 7.1  | System on a chip (SOC) platform and compatibility ..... | 11 |
+| 7.2  | AV decoders .....                                       | 11 |
+| 7.3  | Connectivity .....                                      | 11 |
+| 7.4  | Broadcasting service.....                               | 13 |
+| 7.5  | Channel search.....                                     | 13 |
+| 7.6  | Channel management .....                                | 14 |
+| 7.7  | Channel play .....                                      | 14 |
+| 7.8  | Electronic programme guide (EPG) .....                  | 14 |
+| 7.9  | Subtitles .....                                         | 15 |
+| 7.10 | Programme record and playback .....                     | 15 |
+| 7.11 | Multimedia player .....                                 | 15 |
+| 7.12 | IP streaming and service.....                           | 15 |
+| 7.13 | Browser.....                                            | 15 |
+| 7.14 | Security .....                                          | 16 |
+| 7.15 | System management.....                                  | 16 |
+| 7.16 | Maintenance .....                                       | 17 |
+| 8    | Technical specifications.....                           | 17 |
+| 8.1  | Minimum system .....                                    | 17 |
+| 8.2  | Decoder.....                                            | 17 |
+| 8.3  | Hardware interface .....                                | 19 |
+| 8.4  | Power supply .....                                      | 22 |
+| 8.5  | Software functions .....                                | 22 |
+| 8.6  | Security .....                                          | 24 |
+| 8.7  | OSD .....                                               | 24 |
+| 8.8  | System upgrade .....                                    | 25 |
+| 8.9  | RCU .....                                               | 25 |
+|      | Bibliography.....                                       | 26 |
+
+
+
+# Recommendation ITU-T J.298
+
+# Requirements and technical specifications of a cable TV hybrid set-top box compatible with terrestrial and satellite TV transport
+
+# 1 Scope
+
+This Recommendation describes the requirements and specifications for a hybrid cable set-top box (STB) compatible with terrestrial and satellite TV transport. By combining a mix-mode transmission platform with IP network, the STB can offer new interactive services to cable, satellite and terrestrial TV customers and operators.
+
+# 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 H.262] Recommendation ITU-T H.262 (2012), *Information technology – Generic coding of moving pictures and associated audio information: Video*.
+- [ITU-T H.264] Recommendation ITU-T H.264 (2021), *Advanced video coding for generic audiovisual services*.
+- [ITU-T H.265] Recommendation ITU-T H.265 (2023), *High efficiency video coding*.
+- [ITU-T H.266] Recommendation ITU-T H.266 (2023), *Versatile video coding*.
+- [ITU-T J.83] Recommendation ITU-T J.83 (2007), *Digital multi-programme systems for television, sound and data services for cable distribution*.
+- [ITU-R BT.1306-7] Recommendation ITU-R BT.1306-7 (2015), *Error-correction, data framing, modulation and emission methods for digital terrestrial television broadcasting*.
+- [ITU-R BT.1700] Recommendation ITU-R BT.1700 (2005), *Characteristics of composite video signals for conventional analogue television systems*.
+- [ARIB STD-B21] ARIB STD-B21, *Receiver for digital broadcasting (desirable specifications)*.
+- [ARIB STD-B24] ARIB STD-B24, *Data coding and transmission specification for digital broadcasting*.
+- [ARIB STD-B31] ARIB STD-B31, *Transmission system for digital terrestrial television broadcasting*.
+- [ATSC A/300] ATSC A/300:2023-03, *ATSC 3.0 system*.
+- [ATSC A/321] ATSC A/321:2023-03, *System discovery and signalling*.
+- [ATSC A/322] ATSC A/322:2023-03, *Physical layer protocol*.
+- [ATSC A/332] ATSC A/332:2023-03, *Service announcement*.
+- [ATSC A/342 Part 1] ATSC A/342:2023-03, Part 1, *Audio common elements*.
+
+|                     |                                                                                                                                                                                                                                                                           |
+|---------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| [ATSC A/342 Part 2] | ATSC A/342:2023-03, Part 2, <i>AC-4 system</i> .                                                                                                                                                                                                                          |
+| [ATSC A/342 Part 3] | ATSC A/342:2023-03, Part 3, <i>MPEG-H system</i> .                                                                                                                                                                                                                        |
+| [ATSC A/344]        | ATSC A/344:2023-05, <i>ATSC 3.0 Interactive content</i> .                                                                                                                                                                                                                 |
+| [ATSC A/53 Part 2]  | ATSC A/53, Part 2:2011, <i>RF/Transmission system characteristics</i> .                                                                                                                                                                                                   |
+| [ATSC A/53 Part 5]  | ATSC A/53, Part 5:2014, <i>AC-3 Audio system characteristics</i> .                                                                                                                                                                                                        |
+| [ATSC A/65]         | ATSC A/65C with Amendment No. 1:2013, <i>Program and system information protocol for terrestrial broadcast and cable</i> .                                                                                                                                                |
+| [ATSC A/70 Part 1]  | ATSC A/70, Part 1:2010, <i>Conditional access system for terrestrial broadcast</i> .                                                                                                                                                                                      |
+| [ATSC A/70 Part 2]  | ATSC A/70, Part 2:2011, <i>Conditional access system for terrestrial broadcast service protection using Simulcrypt for IP-delivered services</i> .                                                                                                                        |
+| [ETSI EN 300 421]   | ETSI EN 300 421 V1.1.2 (1997), <i>Framing structure, channel coding and modulation for 11/12 GHz satellite services</i> .                                                                                                                                                 |
+| [ETSI EN 300 468]   | ETSI EN 300 468 V1.17.1 (2022), <i>Specification for service information (SI) in DVB systems</i> .                                                                                                                                                                        |
+| [ETSI EN 300 706]   | ETSI EN 300 706 (2003), <i>Enhanced Teletext specification</i> .                                                                                                                                                                                                          |
+| [ETSI EN 300 743]   | ETSI EN 300 743 (2006), <i>Digital Video Broadcasting (DVB) – Subtitling systems</i> .                                                                                                                                                                                    |
+| [ETSI EN 300 744]   | ETSI EN 300 744 V1.4.1 (2000), <i>Digital video broadcasting (DVB); Framing structure, channel coding and modulation for digital terrestrial television</i> .                                                                                                             |
+| [ETSI EN 302 307-1] | ETSI EN 302 307-1 V1.4.1 (2014), <i>Digital video broadcasting (DVB); Second generation framing structure, channel coding and modulation systems for broadcasting, interactive services, news gathering and other broadband satellite applications; Part 1 (DVB-S2)</i> . |
+| [ETSI EN 302 755]   | ETSI EN 302 755 V1.4.1 (2015), <i>Digital video broadcasting (DVB); Frame structure channel coding and modulation for a second generation digital terrestrial television broadcasting system (DVB-T2)</i> .                                                               |
+| [ETSI TS 100 289]   | ETSI TS 100 289 V1.2.1 (2014), <i>Digital video broadcasting (DVB); Support for use of the DVB scrambling algorithm version 3 within digital broadcasting systems</i> .                                                                                                   |
+| [ETSI TS 102 006]   | ETSI TS 102 006 V1.4.1 (2015), <i>Digital video broadcasting (DVB); Specification for system software update (SSU) in DVB systems</i> .                                                                                                                                   |
+| [ETSI TS 102 366]   | ETSI TS 102 366 V1.4.1 (2017), <i>Digital audio compression (AC-3, Enhanced AC-3) Standard</i> .                                                                                                                                                                          |
+| [ETSI TS 103 190-1] | ETSI TS 103 190-1 V1.3.1 (2018-02), <i>Digital audio compression (AC-4) standard; Part 1: Channel based coding</i> .                                                                                                                                                      |
+| [ETSI TS 103 190-2] | ETSI TS 103 190-2 V1.2.1 (2018-02), <i>Digital audio compression (AC-4) standard; Part 2: Immersive and personalized audio</i> .                                                                                                                                          |
+| [IEC 60603-14]      | IEC 60603-14:1998, <i>Connectors for frequencies below 3 MHz for use with printed boards – Part 14: Detail specification for circular connectors for low-frequency audio and video applications such as audio, video and audio-visual equipment</i> .                     |
+
+|                   |                                                                                                                                                                                                      |
+|-------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| [IEC 61169-2]     | IEC 61169-2:2007, <i>Radio-frequency connectors – Part 2: Sectional specification – Radio frequency coaxial connectors of type 9,52.</i>                                                             |
+| [IEC 61169-24]    | IEC 61169-24:2019, <i>Radio-frequency connectors – Part 24: Sectional specification – Radio frequency coaxial connectors with screw coupling, typically for use in 75 Ω cable networks (type F).</i> |
+| [ISO/IEC 11172-3] | ISO/IEC 11172-3:1993, <i>Information technology – Coding of moving pictures and associated audio for digital storage media at up to about 1,5 Mbit/s – Part 3: Audio.</i>                            |
+| [ISO/IEC 13818-3] | ISO/IEC 13818-3:1998, <i>Information technology – Generic coding of moving pictures and associated audio information – Part 3: Audio.</i>                                                            |
+| [ISO/IEC 13818-7] | ISO/IEC 13818-7:2006, <i>Information technology, Generic coding of moving pictures and associated audio information, Part 7: Advanced Audio Coding (AAC).</i>                                        |
+| [ISO/IEC 14496-2] | ISO/IEC 14496-2:2004, <i>Information technology – Coding of audio-visual objects – Part 2: Visual</i>                                                                                                |
+| [ISO/IEC 14496-3] | ISO/IEC 14496-3:2019, <i>Information technology – Coding of audio-visual objects – Part 3: Audio.</i>                                                                                                |
+| [ISO/IEC 23001-7] | ISO/IEC 23001-7:2023, <i>Information technology – MPEG systems technologies – Part 7: Common encryption in ISO base media file format files.</i>                                                     |
+| [ISO/IEC 23003-3] | ISO/IEC 23003-3:2020, <i>Information technology – MPEG audio technologies – Part 3: Unified speech and audio coding.</i>                                                                             |
+| [ISO/IEC 23003-4] | ISO/IEC 23003-4:2020, <i>Information technology – MPEG audio technologies – Part 4: Dynamic range control.</i>                                                                                       |
+| [ISO/IEC 23008-2] | ISO/IEC 23008-2:2023, <i>Information technology – High efficiency coding and media delivery in heterogeneous environments – Part 2: High efficiency video coding.</i>                                |
+| [ISO/IEC 23008-3] | ISO/IEC 23008-3:2022, <i>Information technology – High efficiency coding and media delivery in heterogeneous environments – Part 3: 3D audio.</i>                                                    |
+| [ISO/IEC 60958-1] | ISO/IEC 60958-1:2004, <i>Digital audio interface – Part 1: General.</i>                                                                                                                              |
+| [ISO/IEC 8859-2]  | ISO/IEC 8859-2:1999, <i>Information technology – 8-bit single-byte coded graphic character sets, Part 2: Latin alphabet No. 2.</i>                                                                   |
+| [TR-069]          | Broadband Forum, 2013, <i>CPE WAN management protocol, Amendment 5.</i>                                                                                                                              |
+| [TR-106]          | Broadband Forum, 2010, <i>Data model template for TR-069-enabled devices, Amendment 5.</i>                                                                                                           |
+| [TR-135]          | Broadband Forum, 2010, <i>Data model for a TR-069 enabled STB, Amendment 1.</i>                                                                                                                      |
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 conditional access system** [b-ITU-T X.1193]: A component of a service and content protection system, the purpose of which is to prevent unauthorized (unentitled) access to a service or to content.
+
+**3.1.2 cable television** [b-ITU-T J.142]: Communications systems distributes broadcast and non-broadcast signals, as well as a multiplicity of satellite signals originating programming and other signals by means of coaxial cable and/or optical fibre.
+
+**3.1.3 electronic programme guide** [b-ITU-T J.90]: A structured multimedia database, intended to provide information on programmes to be broadcast or cablecast.
+
+**3.1.4 hypertext transfer protocol (HTTP)** [b-IETF RFC 2616]: An application-layer protocol used to transmit data over the World-Wide Web.
+
+**3.1.5 network** [b-ITU-T J.94]: A collection of MPEG-2 transport stream (TS) multiplexes transmitted on a single delivery system, e.g., all digital channels on a specific cable system.
+
+**3.1.6 service information (SI)** [b-ITU-T J.94]: Digital data describing the delivery system, content and scheduling/timing of broadcast data streams, etc. It includes MPEG-2 Programme Specific Information (PSI) together with independently defined extensions.
+
+**3.1.7 user interface** [b-ITU-T F.902]: Software and hardware components through which a user can interact with a system.
+
+**3.1.8 video on demand (VOD)** [b-ITU-T Y.1910]: A service in which the end user can, on demand, select and view video content and where the end user can control the temporal order in which the video content is viewed (e.g., the ability to start the viewing, pause, fast forward, rewind, etc.).
+
+**3.1.9 JavaScript** [b-ITU-T J.296]: JavaScript is a scripting language for a web browser. JavaScript is an implementation of the ECMAScript language standard and is primarily used in the form of client-side JavaScript, implemented as part of a web browser in order to provide enhanced-user interfaces and dynamic websites.
+
+**3.1.10 subtitle** [b-ITU-T J.296]: A service of superimposing related text on a TV video broadcast.
+
+**3.1.11 transport stream (TS)** [b-ITU-T J.296]: The broadcast transport stream is composed of MPEG-2 TS signals, which have multi-frame architecture using the same frame length as the orthogonal frequency-division multiplexing (OFDM) frame.
+
+## **3.2 Terms defined in this Recommendation**
+
+This Recommendation defines the following term:
+
+**3.2.1 hybrid set-top box:** A set-top box that uses multiple methods of receiving transmission signals with video and audio content.
+
+NOTE – For the purposes of this Recommendation, the dual streams will be IP-based via the Internet protocols and cable, satellite and terrestrial television, based on the [ITU-T J.83], DVB-S/S2, DVB-T/T2, ISDB-T/Tb, or ATSC 3.0 standards.
+
+# **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                                    |
+|------|----------------------------------------------------|
+| AES  | Advanced Encryption Standard                       |
+| ATIS | Alliance for Telecommunications Industry Solutions |
+| AVC  | Advanced Video Coding                              |
+| CA   | Conditional Access                                 |
+| CAS  | Conditional Access System                          |
+
+|        |                                                                  |
+|--------|------------------------------------------------------------------|
+| CGMS   | Copy Generation Management System                                |
+| CPE    | Customer Premise Equipment                                       |
+| CPU    | Central Processing Unit                                          |
+| CSA    | Common Scrambling Algorithm                                      |
+| CWMP   | Customer premise equipment Wide area network Management Protocol |
+| DC     | Direct Current                                                   |
+| DDR    | Double Data Rate                                                 |
+| DHCP   | Dynamic Host Configuration Protocol                              |
+| DiSEqC | Digital Satellite Equipment Control                              |
+| DMIPS  | Dhrystone Million Instructions Per Second                        |
+| DRM    | Digital Rights Management                                        |
+| EEPROM | Erasable Programmable Read-Only Memory                           |
+| EIT    | Event Information Table                                          |
+| EPG    | Electronic Programme Guide                                       |
+| FCC    | Fast Channel Change                                              |
+| GPU    | Graphics Processing Unit                                         |
+| HD     | High Definition                                                  |
+| HDCP   | High Definition Content Protection                               |
+| HDMI   | High-Definition Multimedia Interface                             |
+| HDR    | High Dynamic Range                                               |
+| HEVC   | High Efficiency Video Coding                                     |
+| HLS    | Hypertext transport protocolLive Streaming                       |
+| HTML   | Hypertext Markup Language                                        |
+| HTTP   | Hypertext Transport Protocol                                     |
+| ICMP   | Internet Control Messages Protocol                               |
+| IGMP   | Internet Group Management Protocol                               |
+| IP     | Internet Protocol                                                |
+| IPTV   | Internet Protocol Television                                     |
+| IPv4   | Internet Protocol version 4                                      |
+| IPv6   | Internet Protocol version 6                                      |
+| LAN    | Local Area Network                                               |
+| LCN    | Logical Channel Number                                           |
+| LNB    | Low Noise Block                                                  |
+| OS     | Operating System                                                 |
+| OSD    | On-Screen Display                                                |
+| OTA    | Over The Air                                                     |
+| OTT    | Over The Top                                                     |
+
+|      |                                     |
+|------|-------------------------------------|
+| PCM  | Pulse Code Modulation               |
+| PIN  | Personal Identification Number      |
+| PIP  | Picture In Picture                  |
+| PSU  | Power Supply Unit                   |
+| PVR  | Personal Video Recorder             |
+| QoE  | Quality of Experience               |
+| QoS  | Quality of Service                  |
+| RAM  | Random Access Memory                |
+| RCU  | Remote Control Unit                 |
+| RF   | Radio Frequency                     |
+| ROM  | Read-Only Memory                    |
+| RTCP | Real-Time Protocol Control Protocol |
+| RTP  | Real-Time Protocol                  |
+| RTSP | Real-Time Streaming Protocol        |
+| SDK  | Software Development Kit            |
+| SDR  | Standard Dynamic Range              |
+| SI   | Service information                 |
+| SOC  | System On a Chip                    |
+| SSU  | System Software Update              |
+| STB  | Set-Top Box                         |
+| TCP  | Transmission Control Protocol       |
+| TDES | Triple Data Encryption Standard     |
+| TP   | Transponder                         |
+| TS   | Transport Stream                    |
+| UA   | Unique Addressing                   |
+| UDP  | User Datagram Protocol              |
+| UHD  | Ultrahigh Definition                |
+| UI   | User Interface                      |
+| USB  | Universal Serial Bus                |
+| VC   | Viewing Card                        |
+| VOD  | Video On Demand                     |
+| VVC  | Versatile Video Coding              |
+| WAN  | Wide Area Network                   |
+
+# 5 Conventions
+
+In this Recommendation:
+
+The phrase "is required to" indicates a requirement which must be strictly followed and from which no deviation is permitted if conformity with this document is to be claimed.
+
+The phrase "is recommended" indicates a requirement which is recommended but which is not absolutely required. Thus this requirement needs not be present to claim conformity.
+
+The phrase "can optionally" indicates an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformity with this Recommendation.
+
+In the body of this Recommendation and its annexes, the words *shall*, *should*, and *may* sometimes appear, in which case they are to be interpreted, respectively, as *is required to*, *is recommended* and *can optionally*.
+
+# **6 Overview**
+
+## **6.1 Overview of hybrid video system**
+
+The overall outline of a content distribution system for a hybrid STB is shown in Figure 6-1. It contains the following parts:
+
+- Content;
+- Service headend;
+- Cable, terrestrial and satellite broadcast path;
+- Over the top (OTT) and Internet protocol television (IPTV) headend;
+- IP network;
+- Hybrid STB device.
+
+![Hybrid STB video system overview diagram showing two parallel video delivery paths: a traditional broadcast path and an IPTV/OTT path, both converging on a Hybrid STB connected to an IP network.](4801720824e4b5e2361a5564f91cfb70_img.jpg)
+
+The diagram illustrates the Hybrid STB video system overview, showing two parallel video delivery paths converging on a Hybrid STB connected to an IP network.
+
+**Content** (On-demand media and Live content) is input to both paths.
+
+**Service head-end** (left path) consists of an **Encoder**, **Multiplexer**, **CA** (Conditional Access), and **Modulator**. The output is **ITU-T J.83/DVB/ISDB broadcast** via **Satellite**, **Terrestrial**, and **Cable**. This path leads to the **Hybrid STB**.
+
+**IPTV/OTT head-end** (right path) consists of a **Decoder and encoder**, **DRM** (Digital Rights Management), **BOSS** (Broadcast Operations Support System), **Streaming server**, and **Middleware**. This path connects to the **IP network**, which is also connected to the **Hybrid STB**.
+
+The **Hybrid STB** is connected to the **IP network**.
+
+J.298(19)\_F6-1
+
+Hybrid STB video system overview diagram showing two parallel video delivery paths: a traditional broadcast path and an IPTV/OTT path, both converging on a Hybrid STB connected to an IP network.
+
+Figure 6-1 – Hybrid STB video system overview
+
+![Figure 6-2 – The hybrid STB hardware block diagram. The diagram shows a central 'Main Chipset' containing a DEMUX, Descrambler, Secure core, CPU, GPU, Decoder, and Display. Surrounding the chip are various modules: ITU-T J.83 frontend, DVB-T/T2 ISDB-T/Tb ATSC 3.0 frontend, DVB-S/S2 frontend, Ethernet LAN, and Wi-Fi module on the top; Flash, DDR, and EEPROM on the left; Analogue AV Out (Analogue audio, Analogue video) and Digital AV Out (HDMI, S/PDIF) on the right; and Power management, Front panel, USB connector, IR receiver, and Smart-card interface on the bottom. A label 'J.298(24)' is in the bottom right corner.](33ed1f9b27c7c21c797aa928b0f06851_img.jpg)
+
+Figure 6-2 – The hybrid STB hardware block diagram. The diagram shows a central 'Main Chipset' containing a DEMUX, Descrambler, Secure core, CPU, GPU, Decoder, and Display. Surrounding the chip are various modules: ITU-T J.83 frontend, DVB-T/T2 ISDB-T/Tb ATSC 3.0 frontend, DVB-S/S2 frontend, Ethernet LAN, and Wi-Fi module on the top; Flash, DDR, and EEPROM on the left; Analogue AV Out (Analogue audio, Analogue video) and Digital AV Out (HDMI, S/PDIF) on the right; and Power management, Front panel, USB connector, IR receiver, and Smart-card interface on the bottom. A label 'J.298(24)' is in the bottom right corner.
+
+J.298(24)
+
+**Figure 6-2 – The hybrid STB hardware block diagram**
+
+The basic hardware diagram for the hybrid STB is shown in Figure 6-2. It contains the following modules:
+
+- Main chipset, the core module of the STB, contains the central processing unit (CPU), graphics processing unit (GPU), audio and video decoder and all the relevant processors;
+- Memory, which is double data rate (DDR) for software execution and erasable programmable read-only memory (EEPROM) and flash for storage;
+- Frontends, which include at least one of ITU-T J.83, DVB-T/T2, DVB-S/S2, ISDB-T/Tb or ATSC 3.0;
+- Power management;
+- Ethernet interface;
+- USB interface;
+- Wi-Fi module;
+- Audio and video output interface;
+- Conditional access system (CAS) smart card interface;
+- Keyboard interface.
+
+## 6.2 The hybrid STB software architecture
+
+Figure 6-3 shows the basic software architecture for the hybrid STB which contains the following modules:
+
+- Hardware on which the software executes;
+- Software development kit (SDK) platform, which includes board configuration, low-level driver, operating system and driver interface;
+
+- Porting layer, which is the porting interface for all the driver and OS operation, and will be called by high-level applications;
+- Applications.
+
+![Diagram of the hybrid STB software architecture showing four layers: Application, API layer, Driver SDK, and Hardware.](5cab96b2d23174c25919840ecd50aa48_img.jpg)
+
+The diagram illustrates the hybrid STB software architecture, organized into four distinct layers separated by dashed lines:
+
+- Application Layer:** Labeled "Middleware application (Platform independently)". It contains two rows of components:
+  - Top row: UI, EPG, Channel management, PVR, Media player.
+  - Bottom row: DVB/ISDB/ATSC stack, CA, DRM, Browser, ...
+- API layer:** Labeled "API porting layer (Unified porting API for different platforms and chipset brands)". It contains two rows of components:
+  - Top row: Frontend, Transport, AV decoder, AV output, Encoder, IR and key.
+  - Bottom row: Media, Security, IO, SCI, Graphic, ...
+- Driver SDK Layer:** Contains two main components:
+  - Driver (light blue box).
+  - OS (FS, events, timers...) (dark grey box).
+- Hardware Layer:** Labeled "Hybrid STB Hardware (Main chipset, flash, DDR, frontend, Ethernet, peripheral)". It is represented by a single grey box at the bottom.
+
+J.298(24)
+
+Diagram of the hybrid STB software architecture showing four layers: Application, API layer, Driver SDK, and Hardware.
+
+**Figure 6-3 – The hybrid STB software architecture**
+
+## 6.3 The hybrid STB categories
+
+To adapt to requirements from different regions and operators, it is recommended to design the hybrid STB taking a modular approach such that different combinations can be supported with configuration changes as opposed to needing full re-design. For instance, DVB-T/T2 may be required in some regions while DVB-S/S2 or ISDB-T/Tb are required in other regions; therefore, the following combination patterns are recommended.
+
+- IP + ITU-T J.83 + DVB-T/T2;
+- IP + ITU-T J.83 + DVB-S/S2;
+- IP + ITU-T J.83 + ATSC 3.0;
+- IP + ITU-T J.83 + ATSC 3.0 + ATSC 1.0;
+- IP + DVB-T/T2;
+- IP + DVB-S/S2;
+- IP + ATSC 3.0;
+- IP + ATSC 3.0 + ATSC 1.0;
+- IP + ITU-T J.83;
+- IP + ITU-T J.83 + ISDB-T/Tb;
+- IP + ISDB-T/Tb;
+- IP + DVB-T/T2 + DVB-S/S2.
+
+# 7 Requirements
+
+The hybrid STB is required to receive and playback AV programmes via cable, satellite/terrestrial and IP transport. Programmes that are protected by CAS and digital rights management (DRM) systems shall be descrambled or decrypted by integrating CAS and DRM solutions from qualified CAS and DRM solution vendors.
+
+## 7.1 System on a chip (SOC) platform and compatibility
+
+The hybrid STB is required to be independent of any specific type of CPU architecture. Multitasking is required to be supported by the CPU.
+
+Embedded GPU hardware is recommended for supporting DirectFB or OpenGL.
+
+The selected system on a chip (SOC) platform is required to be certified by a CAS vendor.
+
+## 7.2 AV decoders
+
+The hybrid STB is required to support the following video coding technologies:
+
+- H.262/MPEG-2 [ITU-T H.262], H.264/MPEG-4AVC (advanced video coding also known as H.264) [ITU-T H.264], and H.265/HEVC (high efficiency video coding, also known as H.265) [ITU-T H.265].
+
+The hybrid STB is recommended to support the following video coding technologies:
+
+- VP9 [b-VP9], AV1 [b-AV1], and H.266/VVC (versatile video coding, also known as H.266) [ITU-T H.266].
+
+The hybrid STB is recommended to support the following audio coding technologies:
+
+- MPEG-1 and MPEG-2 audio as specified in [ISO/IEC 13818-3] and [ISO/IEC 13818-7];
+- MPEG-4 AAC and High Efficiency AAC as specified in [ISO/IEC 14496-3];
+- MPEG-H 3D audio as specified in [ISO/IEC 23008-3];
+- AC-3, E-AC-3 as specified in [ETSI TS 102 366];
+- AC-4 as specified in [ETSI TS 103 190-1] and [ETSI TS 103 190-2].
+
+The decoder is required to switch between an aspect ratio of 4:3 and 16:9 and to perform suitable conversion in a case where an anamorphic video is received.
+
+When ATSC 1.0 is supported in the hybrid STB, audio should conform as specified in [ATSC A/53 Part 5].<sup>1</sup>
+
+When ATSC 3.0 and MPEG-H 3D audio are supported in the hybrid STB, audio should conform as specified in [ATSC A/300], [ATSC A/342 Part 1] and [ATSC A/342 Part 3].
+
+When ATSC 3.0 and AC-4 audio are supported in the hybrid STB, audio should conform as specified in [ATSC A/300], [ATSC A/342 Part 1], and [ATSC A/342 Part 2].
+
+At least simultaneous dual video decoding is recommended for picture in picture (PIP) or fast channel change (FCC) applications.
+
+## 7.3 Connectivity
+
+### 7.3.1 Frontend
+
+The hybrid STB is required to integrate at least one tuner and demodulator for reception of ITU-T J.83, DVB-T, DVB-S, ISDB-T or ATSC 3.0 signals.
+
+---
+
+<sup>1</sup> ATSC A/53 describes the entire ATSC 1.0 system, and comprises multiple parts.
+
+##### **1) ITU-T J.83**
+
+In a case in which ITU-T J.83 frontend is applied in the hybrid STB, an input radiofrequency (RF) connector is required and one RF loop-out connector can be applied optionally.
+
+##### **2) DVB-T/T2**
+
+In a case in which DVB-T/T2 frontend is applied in the hybrid STB, the following requirements apply:
+
+- At least one tuner and demodulator for the reception of signals from terrestrial TV transmitters, with one RF input connector;
+- RF loop-out connector can be applied optionally.
+
+##### **3) ISDB-T/Tb**
+
+In a case in which ISDB-T/Tb frontend is applied in the hybrid STB, an input RF connector is required and one RF loop-out connector can be applied optionally.
+
+##### **4) DVB-S/S2**
+
+In a case in which DVB-S/S2 frontend is applied in the hybrid STB, the following requirements apply:
+
+- At least one tuner and demodulator for reception of signals from satellite TV transmitters, with one RF input connector;
+  - A low noise block (LNB) power supply is required for the RF input connector;
+- RF loop-out connector can be applied optionally.
+
+##### **5) ATSC 3.0**
+
+In a case in which ATSC 3.0 frontend or ATSC 1.0 frontend is applied in the hybrid STB, the following are required:
+
+- At least one tuner and demodulator for the reception of signals from terrestrial TV transmitters;
+- One RF input connector.
+
+In a case in which ATSC 3.0 frontend or ATSC 1.0 frontend is applied in the hybrid STB, the following are optional:
+
+- RF loop-out connector;
+- CTA-909-B Antenna Control Interface [b-CTA-909-B].
+
+#### **7.3.2 IP**
+
+The hybrid STB is required to integrate at least either one Ethernet interface of an RJ45 connector or one Wi-Fi module for wireless connection for network streaming and IP applications.
+
+### **7.3.3 USB**
+
+The hybrid STB is required to install at least one universal serial bus (USB) interface of version 2.0 or higher, for connecting external USB storage.
+
+In addition to one mandatory USB interface, one more USB 2.0 port or higher is recommended.
+
+#### **7.3.4 Key button**
+
+The necessary key buttons on the front panel are recommended, for instance "Power On/Off", "Up" and "Down" buttons, in case the remote control unit (RCU) is not available and so the user can still use the STB with basic operations.
+
+Consideration on additional buttons may be taken per implementation design dependent matters, e.g., "Left", "Right", "Select" and "Menu" buttons to allow navigation through a user interface (UI) and selecting the required parameters and also to select virtual keyboard characters to enter information.
+
+Accessibility considerations are recommended to be addressed by provision of, buttons e.g., closed captioning, teletext, subtitles, audio language selection, voice guided menu and braille buttons.
+
+#### **7.3.5 Infrared/RCU**
+
+The hybrid STB is required to integrate an infrared receiver for STB operation via RCU. RCU is required to have buttons for selection of input source, i.e., to select IP, satellite, terrestrial or cable.
+
+Accessibility considerations are recommended to be addressed by provision of buttons e.g., closed captioning, teletext, subtitles, audio language selection, voice guided menu and braille buttons.
+
+#### **7.3.6 Video output,**
+
+The hybrid STB is required to have at least one high-definition multimedia interface (HDMI) for transmitting HD and UHD with HDR/SDR video output.
+
+For better compatibility with legacy television, an analogue video output interface is recommended, it can be applied as one of the following forms [ITU-R BT.1700]:
+
+- Standard RCA connector for composite video signal;
+- 3.5 mm jack connector for composite video signal.
+
+#### **7.3.7 Audio output**
+
+Digital audio is required to be transmitted via an HDMI output interface.
+
+For better compatibility with legacy television, an analogue audio output interface is recommended, it can be applied as one of the following forms:
+
+- A pair of standard RCA connectors as stereo (L and R) analogue audio signal.
+- 3.5 mm jack connector for stereo analogue audio signal. Generally, it can be applied by sharing the same ear jack for analogue video signal as proposed in clause 7.3.6.
+
+The hybrid STB can optionally have digital audio output interface in coaxial or optical S/PDIF form.
+
+#### **7.3.8 Power supply**
+
+It is required that the power supply comply with the regional low power management standards, for example, Energy Star in the US and the EU code of conduct. The power supply can be an internal integrated module or an external power adaptor. The external power adaptor is recommended; with external power adaptor, the DC power connector is required.
+
+## **7.4 Broadcasting service**
+
+The hybrid STB is required to be able to receive broadcast content of hybrid services, including the following standards:
+
+- ITU-T J.83, DVB-T/T2, ISDB-T/Tb, DVB-S/S2, ATSC 3.0;
+- OTT or IPTV.
+
+## **7.5 Channel search**
+
+The hybrid STB is required to provide a channel searching procedure over the whole available frontend types and over its frequency range. The following requirements are the minimum:
+
+- Support to detect all available source signals: ITU-T J.83, DVB-T/S, ISDB-T/Tb or ATSC 3.0, and IP,
+- Support for automatic and manual channel search.
+- The progress of channel searching procedure is required to be present on an on-screen display (OSD) menu, with received programme information and current frequency being displayed.
+- Search all available tracks for each channel (subtitles, multi-language audios, etc.).
+
+- User can abort the searching process anytime during automatic or manual channel search.
+
+In a case where a DVB-T, ISDB-T/Tb, or ATSC 3.0 frontend is applied in the hybrid STB, a power supply for an antenna preamplifier and its associated configuration menu are required.
+
+In a case in which of DVB-S/S2 frontend is applied in the hybrid STB, the following requirements apply during the channel search process:
+
+- Support power supply for LNB and satellite switcher.
+- Support automatic search and detection of connected satellite networks through DiSEqC switcher. DVB-S/S2 shall be automatically detected.
+- The hybrid STB is available for the user to set up the satellite dish LNB configuration.
+- The hybrid STB will connect to the selected LNB and acquire the signal from the selected satellite automatically.
+
+## 7.6 Channel management
+
+The hybrid STB is required to build a list of all received channels and support a logical channel number (LCN) mechanism. In a case in which there is no LCN descriptor in the services sections of the transport stream, the hybrid STB is required to sort and numerate programmes according to the service ID. The channels from different signals (cable/satellite/terrestrial and IP) are required to be combined.
+
+The hybrid STB is required to support building a favourite channel list by the user; at least eight groups are required to support the favourite list.
+
+The hybrid STB is required to provide an appropriate method and OSD menu to the user for managing the channel list, including the following actions on channels in the channel list:
+
+- Sort and filter;
+- Add to favourite list;
+- Hide/unhide;
+- Lock.
+
+The services being broadcasted by headend of operators may be changed over time. To ensure that the user is always able to access the up-to-date service being broadcasted, the hybrid STB is required to detect and reflect to the user any change with minimal user involvement.
+
+## 7.7 Channel play
+
+The hybrid STB is required to play all the received programmes smoothly (without mosaic or frame freezing), with the following features:
+
+- The hybrid STB is required to display the last channel viewed when it is turned on from main-power or from standby;
+- Support to select and play channels with channel number or in sequence (channel up and channel down);
+- Support to select audio language in case multilanguage audio is available in the current channel;
+- Support to select subtitles language in case multilanguage subtitle is available in the current channel.
+
+## 7.8 Electronic programme guide (EPG)
+
+The hybrid STB is required to support a view of information about shows on programmes, parallel timetable of shows and detailed description of shows.
+
+The electronic programme guide (EPG) shall be implemented in accordance with SI standard [ETSI EN 300 468] when DVB-SI is supported.
+
+The hybrid STB is required to provide displaying EPG based on event information table (EIT) service information, for today, tomorrow and the next seven days (including current day).
+
+The hybrid STB is required to provide a display of the EPG based on [ATSC A/332] information when ATSC 3.0 is supported.
+
+The hybrid STB is required to provide a display of the EPG based on [ATSC A/65] information when ATSC 1.0 is supported.
+
+## **7.9 Subtitles**
+
+The hybrid STB is required to support the decoding and viewing of subtitles and teletext.
+
+## **7.10 Programme record and playback**
+
+The hybrid STB is recommended to support native programme record and playback features based on external USB storage, with the following functions:
+
+- The user is able to record content from the broadcast to the USB storage.
+- The user is able to trick play when an external storage device is connected.
+- Support of immediate recording, scheduled recording and simultaneous playback and recording.
+- Support to display the storage status in the settings menu (Memory usage, format option, etc.).
+- The recorded content shall be re-encrypted by a hardware advanced encryption standard (AES) engine with a chipset unique root key, to make sure the content can be played on the current STB only. Recorded content shall be stored in conformance with the DRM requirements necessary in that region.
+
+## **7.11 Multimedia player**
+
+The hybrid STB is required to support a multimedia player for playing local (via external USB storage) and cloud (via IP) media content.
+
+## **7.12 IP streaming and service**
+
+The hybrid STB is required to support at least one type of http adaptive streaming protocol, such as HLS, MPEG-DASH, Smooth Streaming, etc.; the exact selection will be defined by the operators and broadcasters. The hybrid STB is recommended to support both multicast network technologies for IPTV and unicast network technologies for OTT and support switching from multicast to unicast when necessary and allowed if security parameters are complied with.
+
+## **7.13 Browser**
+
+- a) The hybrid STB is required to integrate a browser which complies with the following:
+  - HTML5 profile compatible;
+  - Support for JavaScript.
+- b) The hybrid STB is required to support an appropriate runtime environment to extend the user experience.
+- c) The hybrid STB is required to support [ATSC A/344] when ATSC 3.0 is provided, and particularly W3C WebSockets [b-W3C-Spec] and the CTA-5000-B User Agent [b-CTA-5000-B].
+
+## 7.14 Security
+
+The hybrid STB is required to comply with all the security requirements of the CAS vendor, with at least the following features required to be applied:
+
+- Embedded advanced security CAS, which will be defined by CAS vendors and operators.
+- Embedded DRM client system for incoming and outgoing streams, which will be defined by operator and content broadcaster.
+- MPEG-CENC [ISO/IEC 23001-7], when ATSC 3.0 is provided.
+- A secure bootloader that shall be stored in the write-protected flash area and a secure boot process with signature verification shall be applied during boot up process; only the signed software can be executed.
+- Secure pairing of the STB with the VC or the UA number for cardless STBs.
+- Support of high-definition content protection (HDCP) copy protection of the latest version on HDMI output.
+- Support of CGMS-A copy protection on analogue video output of the latest version.
+- All content recorded to the USB storage shall be encrypted with a unique chipset root key.
+- Parental control shall be enabled with viewer age ratings and classifications.
+- Secure Wi-Fi connection for Wi-Fi enabled STB and Wi-Fi should connect only to the authorized networks or URL to ensure that it is not used for accessing CAS security keys from external unauthorized illegitimate sources.
+- Allow access to only those apps that are approved by the distribution platform and content provider.
+- STBs are recommended to have capability to support geoblocking.
+- The STBs are recommended to enable forensic watermarking, which is unique per STB at all times when output is available.
+- The STBs are recommended to display visible and unique finger printing per STB when triggered by the headend to enable operators or content providers to collect the subscriber information by such a method as telephone or other voice communication.
+
+## 7.15 System management
+
+### 7.15.1 First time installation
+
+The hybrid STB is required to provide a procedure for the user to set up the STB system configuration during the first power up. The following items are recommended to be included in the set up menu:
+
+- OSD language;
+- Time zone;
+- Aspect ratio;
+- Resolution;
+- Home transponder frequency (this is recommended to be preloaded by the operator for the ease of the consumer, or should be through software OTA downloads);
+- Network setting.
+
+### 7.15.2 System standby
+
+The hybrid STB is required to support a power standby function for better user experience and power efficiency At least one type of the following standby mode is required:
+
+- Active standby mode is required; in this mode, most parts of the hybrid STB are still working normally and the STB can be woken up to normal viewing mode in 3 seconds.
+
+- Passive standby mode is recommended; in this mode, most parts of the hybrid STB are powered down, the power consumption is much lower, while the wake-up time is similar to that of the normal power up process.
+
+## **7.16 Maintenance**
+
+### **7.16.1 Software upgrade**
+
+The hybrid STB is required to provide a software download mechanism for upgrading software modules.
+
+The hybrid STB is required to support at least one of the following upgrade methods:
+
+- OTA;
+- IP.
+
+### **7.16.2 Remote management and diagnostic**
+
+The hybrid STB is recommended to support CPE WAN management protocol (CWMP) according to [TR-069], it is also recommended to support [TR-106] and [TR-135] data models for troubleshooting and collecting the information of QoS/QoE statistics.
+
+# **8 Technical specifications**
+
+This clause defines the technical specification for the implementation of the hybrid STB. All the items in this specification are required to be included but not limited for the specific hybrid STB implementation.
+
+## **8.1 Minimum system**
+
+### **8.1.1 CPU**
+
+The CPU performance of the hybrid STB is required to be more than 2000 DMIPS for execution of the applications, sufficient computing power and a smooth user experience. The selection of CPU architecture is not limited and could be defined by the operators and the STB vendors.
+
+### **8.1.2 GPU**
+
+The hybrid STB is recommended to implement a 3D graphic accelerator supporting OpenGL ES2.0 or above.
+
+### **8.1.3 Memory**
+
+For the supporting web browser and IP related features, the following memory capacity of the hybrid STB is required:
+
+- Flash: 128 Mbytes as minimum;
+- DDR: 512 Mbytes as minimum.
+
+## **8.2 Decoder**
+
+### **8.2.1 Audio**
+
+The hybrid STB is required to support the following mainstream audio codecs:
+
+- PCM audio;
+- MPEG-1 Audio Layer I/II as specified in [ISO/IEC 11172-3];
+- MPEG-2 Audio as specified in [ISO/IEC 13818-3];
+- MPEG-4 High Efficiency AAC v2 Level 4 as specified in [ISO/IEC 14496-3].
+
+NOTE – An HE-AAC decoder will also decode an AAC bitstream.
+
+The hybrid STB is recommended to support the following mainstream audio codecs:
+
+- AC-3/E-AC-3 as specified in [ETSI TS 102 366];
+- AC-4 as specified in [ETSI TS 103 190-1] and [ETSI TS 103 190-2];
+- MPEG-D Extended High Efficiency AAC profile as specified in [ISO/IEC 23003-3], including loudness control profile and dynamic range control profile level 1 (or higher) as specified in [ISO/IEC 23003-4];
+- MPEG-H 3D audio as specified in [ISO/IEC 23008-3].
+
+Manual lip-sync delay up to 400 ms is recommended.
+
+Multichannel audio formats, before transferring to analogue audio output, are required to be converted to stereo format (down mix) and the hybrid STB is recommended to support down mix digital audio output as below for better compatibility:
+
+- AC-3 down mix to stereo for HDMI and S/PDIF;
+- E-AC-3 down mix to stereo for HDMI and S/PDIF;
+- E-AC-3 conversion to AC-3 for pass through HDMI and S/PDIF;
+- AC-4 down mix to stereo for HDMI and S/PDIF;
+- MPEG-H 3D audio down mix to stereo for HDMI and S/PDIF.
+
+The hybrid STB is required to support following output mode for digital audio
+
+- PCM (should be switched ON by default);
+- RAW bitstream.
+
+The STB is recommended to passthrough all audio formats to allow connectivity and decode with Home Theatre systems.
+
+The following audio output modes are required:
+
+- Mono;
+- Dual mono;
+- Stereo.
+
+### 8.2.2 Video
+
+- The hybrid STB is required to support the following mainstream video coding technology:
+  - H.262/MPEG-2: MP@ML, MP@HL [ITU-T H.262];
+  - H.264/MPEG-4 AVC: MP@L3, MP@L4.1, HiP@L4.1 [ITU-T H.264];
+  - H.265/HEVC: Main@L5.1, Main 10@L5.1 (or higher) [ITU-T H.265].
+- The Hybrid STB is recommended to support the following mainstream video coding technology:
+  - H.266/VVC: Main 10@L3.1 [ITU-T H.266];
+  - VP9 [b-VP9];
+  - AV1 [b-AV1].
+- The hybrid STB is required to support down scale HD video to SD display for analogue video output. In addition, if the STB supports UHD or HDR, downscale from UHD to HD and HDR to SDR is required to be supported.
+- The following video resolutions are required to be supported by the hybrid STB:
+  - 1080p;
+  - 1080i;
+  - 720p;
+
+- 576p;
+  - 576i.
+- e) The following video resolutions can optionally be supported by the hybrid STB:
+- 1440p;
+  - 2160p;
+  - 4320p;
+- f) The following aspect ratios are required to be supported:
+- 4:3 centre cut (cropped) 16:9;
+  - 4:3 letterboxed 16:9;
+  - 16:9 pillar boxed 4:3;
+  - 16:9 zoomed 4:3;
+  - Zoom.
+- g) STBs are recommended to support the "stretched to fit TV size" option also.
+
+#### 8.2.3 Picture
+
+The hybrid STB is required to support the following mainstream picture compression formats:
+
+- BMP;
+- GIF;
+- GIF with animation;
+- JPEG up to 8M pixels.
+
+## 8.3 Hardware interface
+
+### 8.3.1 ITU-T J.83 frontend
+
+In a case in which ITU-T J.83 frontend is integrated, the hybrid STB is required to integrate cable frontend in accordance with ITU-T J.83 and to apply the following specifications as well.
+
+- Have an input IEC female connector in accordance with one of the following:
+  - [IEC 61169-2] the characteristic impedance is 75 Ω;
+  - [IEC 61169-24], the characteristic impedance is 75 Ω.
+- Have a minimum frequency bandwidth on input from 50 MHz to 862 MHz.
+- Receive incoming RF signal whose level is in accordance with the defined bandwidth of signal level according to [b-IEC EN 60728-1].
+
+### 8.3.2 DVB-T/T2 frontend
+
+In a case in which the DVB-T/T2 frontend is integrated, the hybrid STB is required to follow the specifications defined in [ETSI EN 300 744] and [ETSI EN 302 755] and apply the following specifications as well:
+
+- Integrate an input IEC female connector in accordance with [IEC 61169-2], the characteristic impedance is 75 Ω;
+- Have a frequency range from 174 MHz to 862 MHz;
+- Support at least -47dBm of input signal;
+- Support 5V@100 mA as maximum DC power to an external antenna with amplifier. The DC power shall be protected against short circuit and there shall be an alternative in the menu system to turn the DC power supply on and off.
+
+### 8.3.3 ISDB-T/Tb frontend
+
+In a case in which ISDB-T/Tb frontend is integrated, the hybrid STB is required to follow the specifications defined in [ARIB STD-B21], [ARIB STD-B31] and [ITU-R BT.1306-7], and to apply the following specifications:
+
+- Integrate an input IEC female connector in accordance with [IEC 61169-2]; the characteristic impedance is 75 Ω.
+- Have a frequency range from 174 MHz to 862 MHz.
+- Support 5V@100 mA as maximum DC power to an external antenna with amplifier. The DC power shall be protected against short circuit and there shall be an alternative in the menu system to turn the DC power supply on and off.
+
+### 8.3.4 DVB-S/S2 frontend
+
+In a case in which the DVB-S/S2 frontend is integrated, the hybrid STB is required to follow the specifications defined in [ETSI EN 300 421] and [ETSI EN 302 307-1] and apply the following specifications:
+
+- Integrate an input IEC F-Type connector in accordance with IEC 169-24 female; the characteristic impedance is 75 Ω.
+- Frequency range from 950 MHz to 2150 MHz as minimum.
+- Signal level from -25 dBm to -65 dBm.
+
+The hybrid STB is required to support LNB control and protection with the following specifications:
+
+- DC power for vertical (13V) and horizontal (18V), capable of maximum 350 mA;
+- Short circuit and over temperature protection;
+- Remote shutdown via SOC;
+- DiSEqC 2.0 or higher;
+- Unicable;
+- 22 kHz tone
+
+### 8.3.5 ATSC 3.0 frontend
+
+In a case in which an ATSC 3.0 frontend is integrated, the hybrid STB is required to follow the specifications defined in [ATSC A/321] and [ATSC A/322] and the following considerations:
+
+- Support an input RF connector.
+- Support an external antenna with optional amplifier. The DC power shall be protected against short circuit and there shall be an alternative in the menu system to turn the DC power supply on and off.
+
+In a case in which the ATSC 3.0 and ATSC 1.0 frontend are integrated, the hybrid STB is required to follow the specifications defined in [ATSC A/321] and [ATSC A/322] and the above ATSC 3.0 frontend specifications, and the specifications defined in [ATSC A/53 Part 2].
+
+#### 8.3.6 HDMI
+
+The hybrid STB is required to integrate a HDMI connector for digital video and audio output; it shall be compliant with the following specifications:
+
+- Type-A (female);
+- HDMI version 1.4a or higher;
+- HDCP version 1.4 or higher.
+
+Content copy protection mechanism of the latest version at the time of production of STB is recommended.
+
+The HDMI CEC feature can be optionally applied in the hybrid STB.
+
+#### **8.3.7 S/PDIF**
+
+The hybrid STB can optionally integrate an S/PDIF interface (either an optical or coaxial connector) for digital audio output; it shall be compliant with [ISO/IEC 60958-1].
+
+### **8.3.8 RCA**
+
+The hybrid STB is recommended to integrate RCA connectors for stereo audio and composite video output. The analogue output is recommended to be enabled with content copy protection mechanisms such as CGMS-A.
+
+### **8.3.9 Ear jack**
+
+The hybrid STB can optionally integrate an ear jack connector for stereo audio and composite video output.
+
+#### **8.3.10 USB**
+
+The hybrid STB is required to integrate at least one USB connector with the following specifications:
+
+- USB Type-A connector, version 2.0 or above;
+- 5V@500 mA power supply as minimum;
+- Comply with USB specification v2.0 or above.
+
+### **8.3.11 Ethernet**
+
+The hybrid STB is required to integrate an Ethernet network interface with the following specifications [IEC 60603-14]:
+
+- RJ 45 connector;
+- IEEE 802.3 10/100Mbase-T;
+- IPv4 (mandatory) and IPv6 (recommended).
+
+The port is recommended to be configurable only by the operator through the remote management capability as defined in clause 7.16.2.
+
+#### **8.3.12 Wi-Fi**
+
+The hybrid STB is recommended to integrate a Wi-Fi network interface with the following specifications:
+
+- Compliant with IEEE 802.11 a/b/g/n standard as minimum;
+- With single band (2.4 GHz) Wi-Fi module as client mode.
+
+The port is recommended to be configurable only by the operator through the remote management capability as defined in clause 7.16.2.
+
+#### **8.3.13 Front panel**
+
+The hybrid STB is recommended to integrate a front panel with the following specifications:
+
+- Front panel buttons: Power On/Off, Up, Down;
+- Infrared receiver;
+- Led light to indicate power status.
+
+Consideration on additional buttons may be taken as per implementation design dependent matters, e.g., "Left", "Right", "Select" and "Menu" buttons to allow navigation through a UI and selecting the required parameters and also to select virtual keyboard characters to enter information
+
+Accessibility considerations are recommended by provision of, buttons e.g., closed captioning / teletext / subtitles, audio language selection, voice guided menu and braille buttons.
+
+## **8.4 Power supply**
+
+The hybrid STB is recommended to work with an external AC/DC power supply unit (PSU) adaptor, connected with a DC jack interface. The hybrid STB and PSU adaptor is required to comply with the following specifications:
+
+- Input voltage: AC 100V to 240V as minimum range;
+- AC frequency: 50/60 Hz.
+
+## **8.5 Software functions**
+
+### **8.5.1 Channel list**
+
+The capability of the channel list is required to support following specifications:
+
+- At least 3000 TV and radio services from the cable/satellite/terrestrial and IP frontend;
+- At least eight groups for favourite channel lists.
+
+The operations on channel list are recommended to have the SORT and FIND functions. The SORT is to sort channels in alphabetic order or FTA/scrambled.
+
+### **8.5.2 Dynamic update**
+
+The hybrid STB is required to support dynamic update as follows:
+
+- Changes in PSI/SI will be applied automatically.
+- All changes will be applied in hidden mode without any action from user.
+
+### **8.5.3 Subtitles**
+
+The hybrid STB is required to support subtitles with the following specifications:
+
+- [ITU-T J.83] Annex A (DVB-C) subtitle in accordance with [ETSI EN 300 743], including characters from code table ISO/IEC 8859-2;
+- [ITU-T J.83] Annex C subtitle in accordance with [ARIB STD-B24];
+- Teletext in accordance with [ETSI EN 300 706];
+- Closed captions in accordance with [b-CEA-608-E], [b-CEA-708-E] and [ARIB STD-B24];
+- Selection of subtitle languages and turning on/off of subtitles.
+
+### **8.5.4 Multiple languages**
+
+The hybrid STB is required to support multiple languages as specified below:
+
+- Support multi-language for OSD menu, audio track and subtitles;
+- Use the language setting to define the default audio track and subtitle language;
+- Support minimum two multilanguage tracks.
+
+#### **8.5.5 PVR and TimeShift**
+
+The hybrid STB is recommended to support personal video recorder (PVR) and TimeShift features, the following mechanisms are required as minimum when PVR and TimeShift are supported:
+
+- Recorded content will be stored as an encrypted transport stream.
+- Recording one channel while watching the other channels on the same carrier is possible.
+
+- The recorded content should include the channel name and programme title if available.
+- The recorded content should be able to be renamed, locked and deleted.
+- While in playback, the user is able to select any of multi-audio and subtitle streams if they are present in the recorded content.
+
+The hybrid STB is required to support the following specification of trick mode:
+
+- Fast forward/backward;
+- Slow forward/backward;
+- Pause and resume.
+
+#### 8.5.6 Media player
+
+The hybrid STB is recommended to implement a media player for playing both local and cloud media content with the following specifications.
+
+- In a case in which the media player is applied in the hybrid STB, the following features are required to be implemented:
+  - Play content from USB external storage devices;
+  - Play content from IP network interface;
+  - Media formats at least: AVI, MP4, TS;
+  - Video coding technology at least: H.262/MPEG-2, MPEG-4 Part 2 (ASP) [ISO/IEC 14496-2], H.264/MPEG-4 AVC;
+  - Audio codecs at least: MPEG-4 AAC, E-AC-3;
+  - Image formats at least: BMP, TIFF, PNG, JPEG.
+- In a case in which the media player is applied in the hybrid STB, the following codecs are recommended to be implemented:
+  - H.265/HEVC, H.266/VVC, AV1, VP9.
+
+#### 8.5.7 Network
+
+The hybrid STB is required to integrate a LAN interface; a Wi-Fi interface is recommended to be integrated.
+
+The hybrid STB is required to support Internet protocol as specified below:
+
+- IPv4, IPv6 (optional);
+- IGMP v1, v2 and v3;
+- ICMP;
+- UDP, TCP, RTP, RTSP/RTCP, HTTP, SSL2.0/3.0;
+- DHCP.
+
+#### 8.5.8 IP streaming
+
+The hybrid STB is required to support IP streaming as specified below:
+
+- Unicast;
+- Multicast.
+
+The hybrid STB is required to support at least one of the following dynamic adaptive streaming standards:
+
+- MPEG-DASH;
+- HLS;
+- Smooth streaming.
+
+## **8.6 Security**
+
+#### **8.6.1 General**
+
+The hybrid STB is required to implement the following general security specifications:
+
+- Memory to memory encryption and random access memory (RAM) scrambling is required.
+- AES-128 encryption and a triple data encryption standard (TDES) algorithm is required.
+- The main chipset of the hybrid STB is required to provide a unique hardware root key.
+- The algorithm of software signature and verification is required to support RSA 2048-bit keys.
+
+#### **8.6.2 CA**
+
+The hybrid STB is recommended to implement a CAS function by fully complying with the detailed specification of the selected CAS vendor.
+
+When DVB-SI is supported, the following basic standard is required for an encryption algorithm:
+
+- DVB-CSA-2/3, AES 128 (ATIS 0800006);
+- DVB-CSA2, which should be implemented in hardware on the chipset.
+
+When DVB-SI is supported, DVB-CSA3 [ETSI TS 100 289] is recommended and should be implemented in hardware on the chipset.
+
+When ATSC 3.0 is supported, the following basic standard is required for an encryption algorithm:
+
+- MPEG-CENC [ISO/IEC 23001-7].
+
+When ATSC 1.0 is supported, the following basic standard is required for an encryption algorithm:
+
+- [ATSC A/70 Part 1] and [ATSC A/70 Part 2].
+
+#### **8.6.3 DRM**
+
+At least one of the DRM standards is required for content protection of IP streaming; the detailed selection of DRM will be decided by the operator and the broadcaster.
+
+#### **8.6.4 Output protection**
+
+The hybrid STB is required to support output protection as follows:
+
+- HDCP (HDCP version 1.4 or above is recommended [b-HDCP]) for HDMI digital video and audio transmission.
+- CGMS-A for analogue video output protection, with [b-CEA-608], [b-CEA-805] standards.
+
+#### **8.6.5 Parental control**
+
+The hybrid STB is required to provide a PIN-controlled parental control feature to perform the following functions:
+
+- Setting age and PIN for viewing single events.
+- Activating or deactivating PIN checking.
+- The STB shall exercise parental control at event level if there is an EIT associated with it.
+
+## **8.7 OSD**
+
+### **8.7.1 User interface**
+
+The hybrid STB is required to support an OSD user interface to the following specifications:
+
+- Support resolution at least 720p;
+- Include system setting, installation, info bar, channel list, EPG;
+
+- Include CAS configuration menu;
+- Support view of system messages and CAS messages.
+
+### 8.7.2 EPG
+
+When DVB-SI is supported, the hybrid STB is required to support the EPG application based on DVB-SI according to [ETSI EN 300 468], and is required to support the following features:
+
+- Support UTF-8 character encoding;
+- Decode full EIT information with capability to display 7 days EPG information.
+
+When ATSC 3.0 is supported, the hybrid STB is required to support the EPG application based on [ATSC A/332] signalling information.
+
+When ATSC 1.0 is supported, the hybrid STB is required to support the EPG application based on [ATSC A/65].
+
+### 8.7.3 Information bar
+
+The hybrid STB is required to implement the information bar as defined in the following specification:
+
+- Showing channel name;
+- Showing now and next event details with time;
+- Showing multi-audio, icon to indicate the presence of subtitle and teletext, and video resolution.
+
+### 8.7.4 CA menu
+
+The hybrid STB is required to implement a CA service menu for presenting the current CAS status and subscriber information; the detailed specification is required to comply with the requirement of the selected CAS vendor.
+
+## 8.8 System upgrade
+
+When an OTA transport stream is used, the hybrid STB is recommended to implement over the air (OTA) system software update (DVB SSU) from the transport stream (TS) in accordance with [ETSI TS 102 006] and other relevant documents.
+
+## 8.9 RCU
+
+The hybrid STB is required to have one RCU, the minimum required keys are listed below:
+
+- Alphanumeric keys;
+- Navigation (up, down, left, right);
+- Power;
+- Menu, EPG, OK, Back, Exit, Colour keys.
+
+RCU is required to have buttons for the selection of the input source, i.e., to select IP, satellite, terrestrial or cable.
+
+Accessibility considerations are recommended by provision of, buttons e.g., for closed captioning/teletext/subtitles, audio language selection, voice guided menu and braille buttons.
+
+## Bibliography
+
+- [b-ITU-T F.902] Recommendation ITU-T F.902 (1995), *Interactive services design guidelines*.
+- [b-ITU-T J.90] Recommendation ITU-T J.90 (2000), *Electronic programme guides for delivery by digital cable television and similar methods – Reference operating scenario and requirements*.
+- [b-ITU-T J.94] Recommendation ITU-T J.94 (2016), *Service information for digital broadcasting in cable television systems*.
+- [b-ITU-T J.142] Recommendation ITU-T J.142 (2000), *Methods for the measurement of parameters in the transmission of digital cable television signals*.
+- [b-ITU-T J.296] Recommendation ITU-T J.296 (2012), *Specification for a hybrid cable set-top box*.
+- [b-ITU-T X.1193] Recommendation ITU-T X.1193 (2011), *Key management framework for secure internet protocol television (IPTV) services*.
+- [b-ITU-T Y.1910] Recommendation ITU-T Y.1910 (2008), *IPTV functional architecture*.
+- [b-AV1] de Rivaz, P., and Haughton, J. (2018), *AV Bitstream and Decoding Process specification*.
+- [b-CEA-608-E] Consumer Electronics Association 608-E-2008 (R2014) (ANSI), *Line 21 Data Services*.
+- [b-CEA-708-E] Consumer Electronics Association 708-E-2013 (ANSI), *Digital Television (DTV) Closed Captioning*.
+- [b-CEA-805] Consumer Electronics Association 805-E-2013 (ANSI), *Data Services on the Component Video Interfaces*.
+- [b-CTA-909-B] Consumer Electronics Association 909-B (R2021) (ANSI), *Antenna Control Interface*.
+- [b-CTA-5000-B] CTA Specification CTA-5000-B *Web Application Video Ecosystem – Web Media API Snapshot 2019*.
+- [b-HDCP] HDCP Interface Independent Adaptation Specification, Revision 2.2, October 16, 2012.
+- [b-IEC EN 60728-1] IEC 60728-1 ed 4.0 (2007), *Cable networks for television signals, sound signals and interactive services*.
+- [b-IETF RFC 2616] IETF RFC 2616 (1999), *Hypertext Transfer Protocol – HTTP/1.1*.
+- [b-VP9] VP9 Bitstream & Decoding Process Specification, Version 0.6 (2016).
+- [b-W3C-Spec] WHATWG: *HTML Living Standard*, Section 9.3 Web sockets, *Web Hypertext Application Technology Working Group*.
+
+
+
+## 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                                                                                                                       |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b>                                                        |
+| 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
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.360**
+
+(11/2006)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+IPCablecom
+
+---
+
+**IPCablecom2 architecture framework**
+
+ITU-T Recommendation J.360
+
+
+
+# **ITU-T Recommendation J.360**
+
+# **IPCablecom2 architecture framework**
+
+# **Summary**
+
+ITU-T Recommendation J.360 provides the architectural framework and technical overview for the expansion of IPCablecom into multimedia.
+
+## **Source**
+
+ITU-T Recommendation J.360 was approved on 29 November 2006 by ITU-T Study Group 9 (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, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2007
+
+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 and overview .....                                       | 1    |
+| 1.1        | Scope .....                                                    | 1    |
+| 1.2        | IPCablecom2 overview .....                                     | 1    |
+| 2          | References.....                                                | 2    |
+| 2.1        | Normative references.....                                      | 2    |
+| 2.2        | Informative references.....                                    | 2    |
+| 3          | Terms and definitions .....                                    | 3    |
+| 4          | Abbreviations and acronyms .....                               | 3    |
+| 5          | IPCablecom2 .....                                              | 5    |
+| 5.1        | Relationship with the 3GPP IMS .....                           | 5    |
+| 5.2        | Overview .....                                                 | 6    |
+| 5.3        | IPCablecom releases and organization.....                      | 10   |
+| 5.4        | IPCablecom2 design considerations.....                         | 13   |
+| 6          | IPCablecom functional components.....                          | 16   |
+| 6.1        | Local network.....                                             | 16   |
+| 6.2        | Access network.....                                            | 16   |
+| 6.3        | Edge.....                                                      | 16   |
+| 6.4        | Core .....                                                     | 17   |
+| 6.5        | IPCablecom multimedia .....                                    | 19   |
+| 6.6        | Application .....                                              | 19   |
+| 6.7        | Interconnect .....                                             | 20   |
+| 6.8        | Operational support systems.....                               | 20   |
+| 7          | Protocol interfaces and reference points.....                  | 22   |
+| 7.1        | Signalling and service control .....                           | 22   |
+| 7.2        | Subscriber data .....                                          | 23   |
+| 7.3        | Quality of service .....                                       | 24   |
+| 7.4        | Network address translation (NAT) and firewall traversal ..... | 26   |
+| 7.5        | Media coding and transport.....                                | 28   |
+| 7.6        | Provisioning, activation, configuration and management .....   | 28   |
+| 7.7        | Network accounting and usage.....                              | 30   |
+| 7.8        | Security.....                                                  | 32   |
+| 7.9        | Lawful intercept.....                                          | 34   |
+| 7.10       | Control point discovery .....                                  | 36   |
+| Appendix I | – SIP signalling overview .....                                | 37   |
+| I.1        | Introduction and purpose.....                                  | 37   |
+| I.2        | References .....                                               | 38   |
+| I.3        | Terms and definitions .....                                    | 39   |
+| I.4        | Abbreviations and acronyms .....                               | 40   |
+
+|                | <b>Page</b>                                              |     |
+|----------------|----------------------------------------------------------|-----|
+| I.5            | IPCablecom2 SIP signalling.....                          | 40  |
+| I.6            | IPCablecom2 IMS requirements .....                       | 46  |
+| Appendix II –  | Quality of service architecture technical overview ..... | 66  |
+| II.1           | Introduction .....                                       | 66  |
+| II.2           | References .....                                         | 66  |
+| II.3           | Terms and definitions .....                              | 67  |
+| II.4           | Abbreviations and acronyms .....                         | 67  |
+| II.5           | QoS requirements and scope .....                         | 67  |
+| II.6           | QoS architecture framework.....                          | 68  |
+| II.7           | Architecture description .....                           | 71  |
+| II.8           | Example procedures .....                                 | 74  |
+| Appendix III – | IPCablecom2 security overview.....                       | 77  |
+| III.1          | Introduction .....                                       | 77  |
+| III.2          | References .....                                         | 77  |
+| III.3          | Terms and definitions .....                              | 78  |
+| III.4          | Abbreviations and acronyms .....                         | 78  |
+| III.5          | IPCablecom2 security.....                                | 78  |
+| III.6          | IPCablecom security requirements.....                    | 89  |
+| Appendix IV –  | IPCablecom2 home subscriber server (HSS) overview .....  | 105 |
+| Appendix V –   | IPCablecom2 NAT and firewall traversal overview .....    | 105 |
+| V.1            | Introduction .....                                       | 105 |
+| V.2            | References .....                                         | 105 |
+| V.3            | Terms and definitions .....                              | 105 |
+| V.4            | Abbreviations and acronyms .....                         | 106 |
+| V.5            | IPCablecom2 NAT requirements and scope .....             | 106 |
+| V.6            | NAT background .....                                     | 107 |
+| V.7            | IPCablecom2 NAT architecture .....                       | 110 |
+| V.8            | Architecture description .....                           | 112 |
+| Appendix VI –  | IPCablecom2 IPv6 and IPv4 strategy overview .....        | 117 |
+
+# IPCablecom2 architecture framework
+
+# 1 Scope and overview
+
+## 1.1 Scope
+
+The initial release of IPCablecom [ITU-T J.160-J.178] provides for telephony. IPCablecom multimedia [ITU-T J.179] creates a bridge that allows for the expansion of IPCablecom into a full range of multimedia services. This Recommendation provides the architectural framework, technical background and project organization for the second release of the IPCablecom family of Recommendations providing for the extension into the multimedia domain.
+
+## 1.2 IPCablecom2 overview
+
+IPCablecom2 is a cable industry effort designed to support the convergence of voice, video, data and mobility technologies. There are tens of millions of cable broadband customers, and the capability of the network to provide innovative services beyond high-speed Internet access is ever-increasing. In particular, real-time communication services based on the IP protocols, such as Voice over Internet Protocol (VoIP), are rapidly evolving and consumers are embracing a wide-range of client devices and media types. It is expected that new technologies, such as Video over IP communications and the ability to display voice and video mail message notifications on a TV-set, will change the way communication and entertainment services are offered. These cutting edge technologies will present exciting new opportunities for cable operators to offer high-value services to consumers in a cost-effective manner.
+
+IPCablecom2 defines an architecture and a set of open interfaces that leverage emerging communications technologies, such as the IETF session initiation protocol (SIP) [IETF RFC 3261], to support the rapid introduction of new IP-based services onto the cable network. A modular approach allows operators to flexibly deploy network capabilities as required by their specific service offerings, while maintaining interoperability across a variety of devices from multiple suppliers. Intentionally non service-specific, the platform should provide the basic capabilities necessary for operators to deploy services in areas such as:
+
+- Enhanced Residential VoIP and IP Video Communications – Capabilities such as video telephony; call treatment based on presence, device capability, identity; and 'Click to dial' type of features.
+- Cross Platform Feature Integration – Capabilities such as caller's name and number identification on the TV and call treatment from the TV.
+- Mobility services and Integration with Cellular and Wireless Networks – Capabilities such as call handoff and roaming between IPCablecom VoIP over WiFi and wireless-cellular networks; voice-mail integration; and single E.164 number (e.g., telephone number).
+- Multimedia Applications – Capabilities such as QoS-enabled audio and video streaming.
+- Commercial Services Extensions – Capabilities such as PBX extension; IP Centrex Services to small to medium-sized businesses; and VoIP trunking for enterprise IP-PBXs.
+- Residential SIP Telephony Extensions – Capabilities such as traditional telephony features (e.g., call waiting, caller ID), operator services, and emergency services.
+
+As noted above, the architecture is designed to support a broad range of services. The IPCablecom2 set of Recommendations define a base architecture, and the components and generic requirements necessary to meet a large number of applications and services. Specific applications and services
+
+rely on this base architecture, but are specified in separate releases. The base specifications should be able to accommodate different applications and services with very few, if any, changes.
+
+This release of IPCablecom is based on Release 6 of the IP multimedia subsystem (IMS) as developed by the 3rd generation partnership project (3GPP). The IMS is a SIP-based architecture for providing multimedia services. IPCablecom2 defines enhancements to the IMS in order to ensure IPCablecom addresses requirements that are not already addressed by the IMS.
+
+It is an important objective of this work that interoperability between IPCablecom 2.0 and 3GPP IMS is provided. IPCablecom 2.0 is based upon 3GPP IMS, but includes additional functionality necessary to meet the requirements of cable operators. Recognizing developing converged solutions for wireless, wireline, and cable, it is expected that further development of IPCablecom 2.0 will continue to monitor and contribute to IMS developments in 3GPP, with the aim of alignment of 3GPP IMS and IPCablecom 2.0.
+
+IPCablecom2 leverages other open standards and specifications wherever possible.
+
+# 2 References
+
+## 2.1 Normative references
+
+*None.*
+
+## 2.2 Informative references
+
+- [ITU-T J.160] ITU-T Recommendation J.160 (2005), *Architectural framework for the delivery of time-critical services over cable television networks using cable modems.*
+- [ITU-T J.170] ITU-T Recommendation J.170 (2005), *IPCablecom security specification.*
+- [ITU-T J.171.1] ITU-T Recommendation J.171.1 (2005), *IPCablecom trunking gateway control protocol (TGCP): Profile 1.*
+- [ITU-T J.178] ITU-T Recommendation J.178 (2005), *IPCablecom CMS to CMS signalling.*
+- [ITU-T J.179 App.I] ITU-T Recommendation J.179 (2005), *IPCablecom support for multimedia. Appendix I: Background information.*
+- [ITU-T J.361] ITU-T Recommendation J.361 (2006), *IPCablecom2 codec media.*
+- [ITU-T J.362] ITU-T Recommendation J.362 (2006), *IPCablecom2 control point discovery.*
+- [ITU-T J.363] ITU-T Recommendation J.363 (2006), *IPCablecom2 data collection to support accounting.*
+- [ITU-T J.364] ITU-T Recommendation J.364 (2006), *IPCablecom2 provisioning, activation, configuration and management.*
+- [ITU-T J.365] ITU-T Recommendation J.365 (2006), *IPCablecom2 application manager interface.*
+- [ES-DCI] PacketCable Electronic Surveillance – *Delivery Function to Collection Function Interface Specification*, PKT-SP-ES-DCI-I01-060914 (2006), Cable Television Laboratories, Inc.
+- [ES-INF] PacketCable Electronic Surveillance – *Intra-Network Functions Specification*, PKT-SP-ES-INF-I01-060406, 6 April 2006, Cable Television Laboratories, Inc.
+- [IETF RFC 3261] IETF RFC 3261 (2002), *SIP: Session Initiation Protocol.*
+
+# 3 Terms and definitions
+
+This Recommendation uses the following terms and definitions:
+
+- 3.1 contact address:** The URI of a user agent on the network. Contact addresses, in the context of IPCablecom are often, but not always, addresses used to deliver requests to a specific user agent.
+- 3.2 E.164:** E.164 is an ITU-T Recommendation which defines the international public telecommunication numbering plan used in the PSTN and other data networks.
+- 3.3 headend:** The central location on the cable network that is responsible for injecting broadcast video and other signals in the downstream direction.
+- 3.4 IMS delta specifications:** Suite of 3GPP IMS specifications modified to reflect cable-specific deltas necessary to comply with IPCablecom.
+- 3.5 IPCablecom multimedia:** An application agnostic QoS architecture for services delivered over DOCSIS networks.
+- 3.6 private identity:** See private user identity.
+- 3.7 private user identity:** Used, for example, for registration, authorization, administration and accounting purposes. A private user identity is associated with one or more public user identities.
+- 3.8 public identity:** See public user identity.
+- 3.9 public user identity:** Used by any user for requesting communications to other users.
+- 3.10 SIP user agent:** Same as 'user agent'.
+- 3.11 server:** A network element that receives requests in order to service them and sends back responses to those requests. Examples of servers are proxies, user agent servers, redirect servers, and registrars.
+- 3.12 subscriber:** An entity (comprising one or more users) that is engaged in a subscription with a service provider.
+- 3.13 subscription:** A contract for service(s) between a user and a service provider.
+- 3.14 user:** A person who, in the context of this Recommendation, uses a defined service or invokes a feature on a UE.
+- 3.15 user agent (UA):** A SIP user agent as defined by [IETF RFC 3261].
+- 3.16 multimedia session:** A set of multimedia senders and receivers and the data streams flowing from senders to receivers. A multimedia conference is an example of a multimedia session.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                    |
+|------|------------------------------------|
+| 3GPP | 3rd Generation Partnership Project |
+| ALG  | Application Layer Gateway          |
+| AM   | Application Manager                |
+| AS   | Application Server                 |
+| BGCF | Breakout Gateway Control Function  |
+| CDF  | Charging Data Function             |
+| CDR  | Call Detail Record                 |
+
+|        |                                                                     |
+|--------|---------------------------------------------------------------------|
+| CM     | Cable Modem                                                         |
+| CMS    | Call Management Server                                              |
+| CMTS   | Cable Modem Termination System                                      |
+| CPE    | Customer Premises Equipment                                         |
+| CSCF   | Call Session Control Function                                       |
+| DHCP   | Dynamic Host Configuration Protocol                                 |
+| DNS    | Domain Name System                                                  |
+| DOCSIS | Data-Over-Cable Service Interface Specification                     |
+| EMS    | Element Management System                                           |
+| E-MTA  | Embedded Multimedia Terminal Adapter                                |
+| ENUM   | E.164 Number Mapping                                                |
+| ESP    | Encapsulating Security Payload                                      |
+| FQDN   | Fully Qualified Domain Name                                         |
+| FW     | Firewall                                                            |
+| GRUU   | Globally Routable User Agent URI                                    |
+| HSS    | Home Subscriber Server                                              |
+| HTTP   | Hyper Text Transfer Protocol                                        |
+| ICE    | Interactive Connectivity Establishment                              |
+| I-CSCF | Interrogating Call Session Control Function                         |
+| IMS    | IP Multimedia Subsystem                                             |
+| IP     | Internet Protocol                                                   |
+| IPSec  | Internet Protocol Security                                          |
+| MG     | Media Gateway                                                       |
+| MGC    | Media Gateway Controller                                            |
+| NA(P)T | Network Address and Port Translation; used interchangeably with NAT |
+| NAT    | Network Address Translation                                         |
+| NCS    | Network-based Call Signalling                                       |
+| NMS    | Network Management System                                           |
+| PAC    | Provisioning, Activation and Configuration element (PAC element)    |
+| PACM   | Provisioning, Activation, Configuration and Management              |
+| PAM    | IPCablecom Application Manager                                      |
+| P-CSCF | Proxy Call Session Control Function                                 |
+| PDS    | Profile Delivery Server                                             |
+| PSI    | Public Service Identity                                             |
+| PSTN   | Public Switched Telephone Network                                   |
+| QoS    | Quality of Service                                                  |
+
+|        |                                       |
+|--------|---------------------------------------|
+| RKS    | Record Keeping Server                 |
+| RTCP   | RTP Control Protocol                  |
+| RTP    | Real-time Transport Protocol          |
+| S-CSCF | Serving Call Session Control Function |
+| SDP    | Session Description Protocol          |
+| SG     | Signalling Gateway                    |
+| SIP    | Session Initiation Protocol           |
+| SLF    | Subscription Locator Function         |
+| SNMP   | Simple Network Management Protocol    |
+| SNTP   | Simple Network Time Protocol          |
+| SS7    | Signalling System No. 7               |
+| STUN   | Simple Traversal of UDP Through NAT   |
+| TCP    | Transmission Control Protocol         |
+| TGCP   | Trunking Gateway Control Protocol     |
+| TLS    | Transport Layer Security              |
+| TR     | Technical Report                      |
+| TURN   | Traversal Using Relay NAT             |
+| UA     | User Agent                            |
+| UDP    | User Datagram Protocol                |
+| UE     | User Equipment                        |
+| URI    | Uniform Resource Identifier           |
+| XCAP   | XML Configuration Access Protocol     |
+| XDS    | XCAP Data Server                      |
+
+# 5 IPCablecom2
+
+The IPCablecom2 architecture describes a set of functional groups and logical entities, as well as a set of interfaces (called reference points) that support the information flows exchanged between entities.
+
+This clause provides:
+
+- An overview of the architecture, including a description of the main functional groupings (e.g., local network, access network, edge, core) and logical entities (e.g., UE, P-CSCF, S-CSCF, HSS) within those groupings.
+- A set of design goals for the IPCablecom2 architecture and specifications.
+- A list of IPCablecom2 Recommendations.
+
+## 5.1 Relationship with the 3GPP IMS
+
+IPCablecom2 is based on Release 6 of the IP multimedia subsystem (IMS) as defined by the 3rd generation partnership project (3GPP). 3GPP is a collaboration agreement between various standards bodies. The scope of 3GPP is to produce Technical Specifications and Technical Reports for GSM and 3rd generation (3G) mobile system networks.
+
+The scope of 3GPP includes development of a SIP-based IP-communications architecture for mobile networks. The resulting architecture, dubbed the IP multimedia subsystem, defines how various protocols (e.g., SIP and DIAMETER) can be used in a system-level architecture to provide SIP-based communication services.
+
+Within the overall IPCablecom goal to leverage existing industry standards whenever possible is an objective to align with the IMS architecture and specifications being developed by 3GPP. Specifically, IPCablecom2 reuses many of the basic functional entities and reference points defined in the IMS. The primary motivation behind this design objective is to align with a set of standards that are widely supported by vendor products, and therefore, minimize the product development effort required to deploy IPCablecom networks.
+
+While many of the functional entities and reference points defined in the IMS have broad applicability in other industries, Release 6 of the IMS is a wireless-centric architecture designed to meet the business and operational needs of the wireless industry. Therefore, it does not meet all of the needs of the cable industry. IPCablecom2 enhances the IMS to support the unique technology requirements of the cable industry, and also addresses cable operator business and operating requirements.
+
+3GPP is developing newer releases of the IMS specifications. Future updates to IPCablecom will align with these newer releases as necessary.
+
+Refer to [TS 23.002] for additional information on the 3GPP IMS architecture.
+
+## 5.2 Overview
+
+The IPCablecom2 architecture is based on the IMS architecture, with some incremental extensions as noted in clause 5.1. Extensions include use of additional or alternate functional components compared with the IMS architecture, as well as enhancements to capabilities provided by the IMS functional components.
+
+Some of the major IPCablecom enhancements to the IMS include:
+
+- Support for Quality of Service (QoS) for IMS-based applications on DOCSIS access networks, leveraging the IPCablecom Multimedia architecture [ITU-T J.179 App.I].
+- Support for signalling and media traversal of network address translation (NAT) and firewall (FW) devices, based on IETF mechanisms.
+- Support for the ability to uniquely identify and communicate with an individual when multiple UEs are registered under the same public identity.
+- Support for additional access signalling security and UE authentication mechanisms.
+- Support for provisioning, activation, configuration and management of UEs.
+
+An overview of the IPCablecom2 architecture elements and functional groupings is illustrated in Figure 1.
+
+![Figure 1 – IPCablecom reference architecture diagram showing layers from Interconnect to Local network.](4e4be0bd8b235167902f2c03e41da651_img.jpg)
+
+The diagram illustrates the IPCablecom reference architecture, organized into several functional layers:
+
+- Interconnect Layer:**
+  - Peer network:** Connected to a **Border element** containing an **Interconnect proxy** and a **Media proxy**.
+  - PSTN:** Connected to a **PSTN GW** containing **SG**, **MGC**, and **MG**, which is also connected to a **BGCF**.
+  - PacketCable E-MTAs:** Connected to a **CMS**.
+- Operational support systems:** A group of systems including **DNS**, **DHCP**, **Time**, **ENUM**, **PAC**, **NMS & EMS**, and **CDF**.
+- Core Layer:** Contains **SLF**, **HSS**, **I-CSCF**, and **S-CSCF**.
+- Application Layer:** Contains a **Presence server** and an **Application server**.
+- IP Cablecom multimedia Layer:** Contains a **Policy server**.
+- Edge Layer:** Contains **TURN server**, **STUN server**, **P-CSCF**, and the **IP Cablecom application manager**.
+- Access network Layer:**
+  - Contains a **CMTS** connected to multiple **Cable modems** via **DOCSIS**.
+  - One **Cable modem** is connected to an **E-MTA** and another **Cable modem**.
+  - Another **Cable modem** is connected to a **NAT & firewall**.
+  - An **Other** category includes an **Access point**.
+- Local network Layer:**
+  - Contains five **UE** (User Equipment) blocks.
+  - Three UEs are connected directly to the **CMTS** via their respective **Cable modems**.
+  - One UE is connected to the **CMTS** via a **Cable modem** and a **NAT & firewall**.
+  - The fifth UE is connected to an **Access point** under the **Other** category.
+
+Figure 1 – IPCablecom reference architecture diagram showing layers from Interconnect to Local network.
+
+J.360\_F01
+
+**Figure 1 – IPCablecom reference architecture**
+
+The architecture provides a rich and modular platform upon which a variety of multimedia communication services can be built for a diverse set of UEs. Note the reference architecture depicts several different UE deployment scenarios (e.g., UE behind a CM, a NAT and firewall gateway between the UE and CM). These deployment scenarios are meant to illustrate the fact that UEs can be deployed in many different environments and configurations. The reference architecture does not provide an exhaustive set of deployment scenarios.
+
+IP Cablecom2 assumes a user model composed of users, public identities, UEs and devices. The potential relationships between users, public identities, UEs and devices are described in Appendix IV. For example, a user may have multiple user equipment (UE) devices, each of which may be registered to one or more public identities. A public identity can be an E.164 number or it can be an alphanumeric identifier that makes sense in the context of a SIP telephony service. Each public identity is generally associated with a user.
+
+The architecture is divided into several logical areas or functional groupings:
+
+- **Local network:** The local network is the network that the user equipment (UE) uses to connect to the access network. It may be Ethernet, WiFi, bluetooth, or any other technology
+
+used to network or connect UEs. There may be a NAT and firewall gateway between the local network and the access network. In some instances, the UE may include an access network component. In such instances, the local network is an internal interface within the UE. This is the case with a UE that has an embedded DOCSIS cable modem.
+
+A UE encompasses either a software-based application or a hardware-based device where service features are invoked, executed, or rendered for the subscriber. UEs all use the same basic SIP infrastructure to obtain real-time IP communication and multimedia services. An IPCablecom UE may be built in a modular fashion, and can contain varying levels of functionality based on the capabilities that it needs to support. For example, a UE may only support text-based instant messaging (IM), and thus will not need to support audio or video codecs. A NAT and firewall device may exist between a UE on a local network and the access network. As such, mechanisms are required to enable signalling and media traversal of NAT/FWs.
+
+- Access network: A UE may reside on or be connected to the DOCSIS access network, or they may obtain services from other access networks (including other cable access networks not under the control of the cable operator owns the IPCablecom subscription); this is especially important for a mobile UE such as a laptop, WiFi-enabled phone, etc. When a UE is in the cable access network, it can obtain access network QoS by interacting with the cable networks SIP signalling infrastructure, which in turn interacts with the IPCablecom multimedia infrastructure via the IPCablecom application manager and policy server to reserve resources in the cable access network.
+
+IPCablecom E-MTAs are included in the reference diagram for completeness.
+
+- Edge: This functional grouping encompasses reference points that are provided to a UE and the access network. A UE obtains access to the SIP Infrastructure through the proxy call session control function (P-CSCF). The P-CSCF proxies SIP messages between the UE and the rest of the architecture and maintains security associations with the UE. The P-CSCF may request access network QoS resources upon session initiation on behalf of the UE via the IPCablecom application manager. The IPCablecom application manager interfaces with the IPCablecom multimedia policy server, which pushes QoS policy to the cable access network components. IETF STUN and TURN servers are used to enable media access through NAT & FW devices (the P-CSCF uses a separate STUN server for signalling access through NAT & FW devices). IPCablecom E-MTAs are served by their CMS as described in IPCablecom 1.5 architecture framework technical report [ITU-T J.160].
+- Core: The core contains the basic components required to provide SIP services and subscriber data. The core functional grouping consists of the following functional components: Interrogating-CSCF (I-CSCF), Serving-CSCF (S-CSCF), subscription location function (SLF) and home subscriber server (HSS).
+- The I-CSCF is the initial entry point into the core for SIP. The I-CSCF cooperates with the HSS to determine the S-CSCF to be assigned to a public identity, and routes requests originated by a UE to the S-CSCF assigned to the originating UE's public identity. The I-CSCF also routes terminating SIP requests received from within the network or from outside networks. In this case, the I-CSCF consults the HSS to determine the S-CSCF that is assigned to a terminating public identity, and route the SIP request to that S-CSCF for processing. The I-CSCF can also provide topology hiding when communicating with outside networks.
+- The S-CSCF is responsible for SIP session processing. Calls or multimedia communication sessions initiated to and from public identities are sent to the assigned S-CSCF for authorization and processing. The S-CSCF has a service control framework that evaluates SIP requests against pre-defined filter criteria for a subscriber, or determines if the SIP request should be routed to an application server for processing. This enables an
+
+extensible architecture for rapid introduction of value-added features and services. The S-CSCF may route SIP messages to application servers, presence servers, other CSCFs, or breakout gateway control functions (BGCFs) as appropriate. The S-CSCF also includes the SIP registrar function, which maps public identities to their registered SIP contact addresses, assigns globally routable user agent URIs (GRUUs), and stores any other parameters associated with the registration, e.g., SIP user agent capabilities. The S-CSCF obtains subscription data from the HSS.
+
+- The HSS provides access to user profiles and other provisioned subscriber data to the S-CSCF and application servers. The HSS also maintains the assignment of a public identities to an S-CSCF. A subscription may be associated with multiple public identities. An HSS maps a subscription to a S-CSCF; meaning that all the public identities will be assigned to the same HSS.
+- S-CSCFs and application servers may store certain classes of data associated with subscriptions in the HSS.
+- The SLF is used to locate an HSS instance for a given identity when multiple HSSs are present.
+- Applications: The application server functional grouping defines application servers that may be invoked as part of originating or terminating request treatment on a S-CSCF for a given user, or they may be stand-alone application servers that can be invoked and operate independently. The presence server is a specialized application server that contains presence data for public identities. The presence data is obtained from a variety of sources in the network and provides a view of the willingness and availability of the user for communications. Privacy handling and subscription authorization of presence data is handled by the presence server as well.
+- Interconnect: The interconnect functional grouping enables connections with other networks. Interconnect with the PSTN is handled via the breakout gateway control function (BGCF), which determines the media gateway controller (MGC) to utilize for PSTN interconnect. The MGC controls media gateways (MG) which provide transport layer and bearer interconnect to the PSTN. Signalling gateways (SG) provide SS7 connectivity. The IPCablecom MGC, SG and MG are used to interconnect to the PSTN. Interconnect with peer Voice over IP (VoIP) networks may be achieved through a border element. The Border Element contains Interconnect Proxy functionality and optionally Media Proxy functionality that may be on separate platforms. The Interconnect Proxy may perform a variety of tasks, including protocol profile enforcement and signalling conversion, as needed to interwork with other networks. The Media Relay may relay media for the purposes of topology hiding. The IPCablecom CMS is located in the Interconnect functional grouping to indicate that E-MTAs that it serves can communicate with UEs.
+- Operational Support Systems: Operational Support Systems provide various functions like accounting and UE provisioning. The CDF collects accounting messages from various elements, DHCP helps with the distribution of IP addresses to UEs, ENUM and DNS aid in the resolution of URIs and FQDNs, PAC and XDS support provisioning and configuration of UEs, and EMSs and NMSs assist with monitoring and management functions.
+
+Note that the functional components described above are logical functions, which may be combined on common platforms.
+
+## 5.3 IPCablecom releases and organization
+
+### 5.3.1 IPCablecom releases
+
+The IPCablecom architecture continues to evolve as new capabilities are added, and as such is comprised of several releases.
+
+- Release 1.0 – This release provides support for a telephony application using E-MTAs; it is specified in the initial release of ITU-T Recs J.160-J.178.
+- Release 1.5 – This release provides incremental new capabilities and adds SIP for session management within and among IPCablecom networks; it is specified in the revisions to ITU-T Recs J.160-J.178.
+- Multimedia – This release separates out the QoS capabilities and defines a generic QoS architecture; it is specified in [ITU-T J.179].
+- Release 2 – This release adds support for SIP-based endpoints, and a SIP-based service platform that may be used to support a variety of services.
+
+Figure 2 illustrates the IPCablecom releases. Applications that make use of the SIP service platform will be defined in separate stand-alone releases and are not depicted in Figure 2.
+
+![Diagram illustrating the IPCablecom releases hierarchy. Release 2 is the outermost container, containing Release 1.5, which in turn contains Release 1.0. The Multimedia release is shown as a dashed box within Release 2, separate from the nested releases.](a83ba9e3e2c1e21dd69953a7b09e45b4_img.jpg)
+
+The diagram shows a hierarchy of releases. At the top level is a large grey rectangle labeled 'Release 2'. Inside this rectangle, at the top, is a dashed box labeled 'Multimedia'. Below the 'Multimedia' box is a solid grey rectangle labeled 'Release 1.5'. Inside the 'Release 1.5' rectangle is a white rectangle labeled 'Release 1.0'. The labels 'Release 2', 'Multimedia', 'Release 1.5', and 'Release 1.0' are centered within their respective boxes.
+
+J.360\_F02
+
+Diagram illustrating the IPCablecom releases hierarchy. Release 2 is the outermost container, containing Release 1.5, which in turn contains Release 1.0. The Multimedia release is shown as a dashed box within Release 2, separate from the nested releases.
+
+**Figure 2 – IPCablecom releases**
+
+### 5.3.2 IPCablecom organization
+
+The organization of this IPCablecom2 release is based upon the need to both align with and extend the IMS. Figure 3 illustrates the scope of the IPCablecom2 release.
+
+![Diagram illustrating the IPCablecom2 organization structure. The diagram shows four main components: Architecture framework Recommendation, Technical overview, Recommendations, and IMS delta Recommendation. The Architecture framework Recommendation is at the top, connected to the Technical overview and Recommendations. The Technical overview and Recommendations are connected to the IMS delta Recommendation. The IMS delta Recommendation is connected to External specification or standard (e.g., 3GPP, IETF). A legend indicates that the shaded area represents the scope of IPCablecom release 2, solid lines represent references to other IPCablecom documents, and dashed lines represent references to external specifications or standards.](2cde062fd82833415971a8bd1a2cafab_img.jpg)
+
+The diagram illustrates the organization of the IPCablecom2 release. It features four main components arranged in a hierarchical structure:
+
+- Architecture framework Recommendation** (at the top)
+- Technical overview** and **Recommendations** (below the Architecture framework Recommendation)
+- IMS delta Recommendation** (below the Technical overview and Recommendations)
+- External specification or standard (e.g., 3GPP, IETF)** (below the IMS delta Recommendation)
+
+Connections between components are as follows:
+
+- Solid lines connect the Architecture framework Recommendation to the Technical overview and Recommendations.
+- Solid lines connect the Technical overview and Recommendations to the IMS delta Recommendation.
+- Dashed lines connect the IMS delta Recommendation to the External specification or standard.
+
+A legend on the right side of the diagram defines the visual elements:
+
+- A shaded gray box represents the **Scope of IPCablecom release 2**.
+- A solid line represents a **Reference to other IPCablecom documents**.
+- A dashed line represents a **Reference to external specification or standard**.
+
+The diagram is labeled **J.360\_F03** at the bottom right.
+
+Diagram illustrating the IPCablecom2 organization structure. The diagram shows four main components: Architecture framework Recommendation, Technical overview, Recommendations, and IMS delta Recommendation. The Architecture framework Recommendation is at the top, connected to the Technical overview and Recommendations. The Technical overview and Recommendations are connected to the IMS delta Recommendation. The IMS delta Recommendation is connected to External specification or standard (e.g., 3GPP, IETF). A legend indicates that the shaded area represents the scope of IPCablecom release 2, solid lines represent references to other IPCablecom documents, and dashed lines represent references to external specifications or standards.
+
+**Figure 3 – IPCablecom2 organization**
+
+This architecture framework Recommendation describes the IPCablecom2 architecture at a high level. Individual functional areas (e.g., SIP, NAT and FW traversal, security, etc.) have dedicated appendices or Recommendations. The purpose of these documents is to capture architecture issues and expected usage of the IMS for cable. A document may be a specification if it documents normative requirements and defines reference points that are specific to IPCablecom, or if it includes a very small number of changes to an IMS specification (i.e., the number of changes made to an IMS specification was not sufficient to warrant releasing an IMS Delta specification).
+
+In some cases, these documents do not draw on any IMS architectural components or reference points. However, in general these documents are based upon the IMS and in some cases enhance the IMS. Documents that are based upon the IMS simply refer to IMS documents in the same way any other document is normatively referenced. Enhancements to the IMS are contained in IMS Delta specifications. IMS Delta specifications are republished IMS specifications that contain changes based upon cable-specific requirements. Depending on the way the IMS documents are organized, an IMS Delta specification may contain changes to accommodate a number of different IPCablecom specifications or TRs. For example, the IMS Delta Specification for 3GPP TS 24.229 contains changes for the functional areas of SIP, NAT & FW traversal, security and QoS.
+
+The goal is to introduce the IPCablecom enhancements to the IMS into the actual 3GPP specifications. As this occurs, IMS Delta specifications may be withdrawn and replaced with direct references to 3GPP IMS specifications.
+
+Table 1 contains a list of Recommendations.
+
+**Table 1 – IPCablecom2 Recommendations**
+
+| <b>IPCablecom2 Recommendations reference number</b> | <b>Document name</b>                                                             |
+|-----------------------------------------------------|----------------------------------------------------------------------------------|
+| J.360                                               | Architecture framework (this Recommendation)                                     |
+| Appendix I                                          | IPCablecom2 SIP Signalling Overview                                              |
+| Appendix II                                         | IPCablecom2 QoS Overview                                                         |
+| Appendix III                                        | IPCablecom2 Security Overview                                                    |
+| Appendix IV                                         | IPCablecom2 Home Subscriber Server (HSS) Overview                                |
+| Appendix V                                          | IPCablecom2 NAT and Firewall Traversal Overview                                  |
+| Appendix VI                                         | IPCablecom2 IPv6 and IPv4 Strategy Overview                                      |
+| <b>IPCablecom Recommendation reference number</b>   | <b>Recommendation name</b>                                                       |
+| J.362                                               | IPCablecom2 control point discovery                                              |
+| J.365                                               | IPCablecom2 application manager interface                                        |
+| J.364                                               | IPCablecom2 provisioning, activation, configuration and management               |
+| J.361                                               | IPCablecom2 codec media                                                          |
+| J.363                                               | IPCablecom2 data collection to support accounting                                |
+| <b>IMS delta specification reference number</b>     | <b>Document name</b>                                                             |
+| J.366.0                                             | Overview of IPCablecom2 IMS Delta Recommendations                                |
+| J.366.1                                             | IPCablecom2 Organization of Subscriber Data Specification 3GPP TS 23.008         |
+| J.366.2                                             | IPCablecom2 IP Multimedia Call Model Stage 2 Specification 3GPP TS 23.218        |
+| J.366.3                                             | IPCablecom2 IP Multimedia Subsystem Stage 2 Specification 3GPP TS 23.228         |
+| J.366.4                                             | IPCablecom2 SIP and SDP Stage 3 Specification 3GPP TS 24.229                     |
+| J.366.5                                             | IPCablecom2 Cx and Dx Interfaces Specification 3GPP TS 29.228                    |
+| J.366.6                                             | IPCablecom2 Cx and Dx Interfaces, Diameter Protocol Specification 3GPP TS 29.229 |
+| J.366.7                                             | IPCablecom2 Access Security for IP-Based Services Specification 3GPP TS 33.203   |
+| J.366.8                                             | IPCablecom2 Network Domain Security Specification 3GPP TS 33.210                 |
+| J.366.9                                             | IPCablecom2 Generic Authentication Architecture Specification 3GPP TS 33.220     |
+
+As described in clause 1.2, this IPCablecom2 release defines a base architecture upon which applications can be built. While these applications rely on the base architecture, they are independent of the base architecture and are specified in separate releases.
+
+## 5.4 IPCablecom2 design considerations
+
+In order to enable real-time IP communications across the cable network infrastructure, IPCablecom2 specifications define technical requirements and specify reference points in the following areas:
+
+- Signalling and service control.
+- Subscriber data.
+- Network address translation (NAT) and firewall traversal.
+- Quality of service.
+- Media stream transport and encoding.
+- Provisioning, activation, configuration and management.
+- Network accounting and usage.
+- Security.
+- Lawful intercept.
+
+### 5.4.1 Generic architecture goals
+
+The design goals of the IPCablecom2 architecture include:
+
+- Provide a service-independent architecture that allows new services to be added without impacting the underlying service control platform.
+- Provide a modular architecture, where architectural components can be combined in a variety of ways to support a wide range of features. For example, a UE could be built from a mix of basic building blocks such as SIP user agents, media endpoints, presence watchers, and event subscribers.
+- Support many-to-many relationships between users, endpoint devices and sessions.
+- Support a wide variety of UE devices, including soft or hard UEs, smart UEs, wired or wireless UEs.
+- Support IPv4 and IPv6 operation.
+- Support interworking with previous releases of IPCablecom.
+- Support UE mobility so that a UE can access services from any access network, not just the cable access network. In general, mobility within the context of IPCablecom means that a UE with IP connectivity can access IPCablecom services. While this is different than 3GPP-style roaming (i.e., the P-CSCF may be located in the visited network), the IPCablecom enhancements should not break the 3GPP roaming model.
+- Leverage existing standards and open protocols whenever possible. Most importantly, adopt the IMS architecture and define incremental extensions as necessary.
+
+### 5.4.2 Signalling and service control
+
+IPCablecom2 signalling and service control design goals include:
+
+- Support multiple service control models. These models include: control in the UE, control in the network, and shared control. It is up to each specific application that uses IPCablecom to define the service control model.
+- Support ability for users to establish communication sessions with other users in the same network, with users in peering networks, or with the PSTN.
+- Support unregistered UEs for emergency services and UE configuration.
+
+### 5.4.3 Subscriber data
+
+IPCablecom2 subscriber data design goals include:
+
+- Define a logical entity which is the central repository for end user or subscription information needed for the invocation or execution of services by CSCFs and application servers.
+- Allow for the centralized storage and distribution of persistent and semi-persistent data.
+
+### 5.4.4 Network address and port translation (NA(P)T) and firewall traversal
+
+IPCablecom2 NAT (NAT and NAPT are used interchangeably) and firewall traversal design goals include:
+
+- Not imposing any requirements on the NAT devices nor require the network to be aware of the presence of a NAT.
+- Support for multiple UEs behind a single NAT.
+- Ability to support both inbound requests from and outbound requests to UEs through NATs.
+- Ability to maintain bindings to multiple P-CSCFs to provide reliable inbound message delivery in the face of a P-CSCF failure.
+- Support the traversal of NATs between the UE and network (home NAT, visited network NAT).
+- Be application independent, meaning the solution should employ mechanisms that can be used by non-SIP-based applications. However, these solutions may require application support in order to use the defined mechanism.
+- Avoid unnecessarily long media paths due to media pinning.
+- Ability to re-establish communications in failure situations (e.g., the NAT/FW device re-boots and NAT bindings are lost).
+
+### 5.4.5 Quality of service
+
+IPCablecom2 QoS design goals include:
+
+- Leverage the IPCablecom Multimedia specification in order to provide QoS when a subscriber is accessing service through the DOCSIS network.
+- Support packet marking and classification from the access network such that a QoS mechanism like Differentiated Services (DiffServ) can be used in the backbone.
+- Provide a mechanism that does not require applications to be aware of access network topology.
+
+### 5.4.6 Media stream transport and encoding
+
+IPCablecom2 media stream transport and encoding design goals include:
+
+- Minimize the effects of latency, packet loss and jitter on sensitive media streams (e.g., voice and video) to ensure a quality level in the target environments (including audio/video telephony, IP video streaming and wireless).
+- Define a set of audio and video codecs and associated media transmission protocols that may be supported.
+- Accommodate emerging narrow-band and wideband voice codec technologies.
+- Accommodate emerging video codec technologies to provide support for applications like video telephony, IP video streaming, etc.
+- Specify minimum requirements for echo cancellation and voice activity detection.
+
+- Support transparent, error-free dual-tone multi frequency (DTMF) transmission.
+- Support for fax relay, modem relay, DTMF relay, and TTY.
+- Support calculation and reporting of voice quality metrics.
+
+### **5.4.7 Provisioning, activation, configuration and management (PACM)**
+
+IPCablecom2 PACM design goals include:
+
+- Support lightweight static and dynamic PACM models, considering both controlled (UE's local network under service provider's control) and uncontrolled environments (UE's local network not under service provider's control).
+- Support a non-DHCP based P-CSCF discovery mechanism.
+- Support a multi-layered PACM framework for UEs, services and users; allowing for separate PACM definitions for each layer.
+- Support for software upgrade methods for UEs.
+- Support multiple operational models (i.e., branded and unbranded).
+
+### **5.4.8 Network accounting and usage**
+
+IPCablecom2 network accounting and usage design goals include:
+
+- Enable the ability to account for network usage and activities in both real-time.  
+In this case, real-time is relative to when the events are sent to the central repository and does not imply when the final bill may be available to the customer nor that events are sent to indicate incremental usage of network resources (i.e., on-line charging).
+- Allow for multiple network elements to generate events which can be correlated to a given session or subscriber.
+- Support the correlation of accounting events across the signalling and bearer planes.
+- Facilitate the rapid introduction of features and services by minimizing the impact to other network elements and their need to signal feature and service related information.
+
+### **5.4.9 Security**
+
+IPCablecom2 security design goals include:
+
+- Support for confidentiality, authentication, integrity and access control mechanisms.
+- Protection of the network from various denial of service, network disruption, theft-of-service attacks.
+- Protection of the UEs from denial of service attacks, security vulnerabilities, unauthorized access (from network).
+- Support for end-user privacy through encryption and mechanisms that control access to subscriber data such as presence information.
+- Mechanisms for UE authentication, secure provisioning, secure signalling, secure media and secure software download.
+
+### **5.4.10 Lawful intercept**
+
+IPCablecom2 lawful intercept design goals include:
+
+- Support a service independent intercept architecture that is not tightly coupled to basic IPCablecom service capabilities.
+- Maximize transparency of the surveillance within the network.
+- Ensure the surveillance architecture does not constrain the design of applications.
+- Support for interception of calls that are executed across NCS and SIP.
+
+# **6 IPCablecom functional components**
+
+This clause provides additional detail on each of the functions in the IPCablecom architecture.
+
+## **6.1 Local network**
+
+### **6.1.1 User equipment (UE)**
+
+IP Cablecom supports NCS-based clients for telephony services. IPCablecom multimedia provides a service agnostic QoS and accounting framework. IPCablecom2 adds support for SIP-based clients with a variety of capabilities, e.g., soft and hard phones, smart phones, wireless and wired phones, instant messaging UEs, video communications terminals, etc. Consistent with IMS, IPCablecom clients are called user equipment (UE). All of the various UEs described previously use the same basic infrastructure to obtain multimedia services. UEs may be fixed or mobile devices such as laptops or WiFi-enabled phones. They may reside on the cable access network, or they may obtain services from other access networks. When UEs are in the cable access network, they can obtain access network QoS by interacting with the signalling infrastructure, which in turn interacts with the IPCablecom multimedia policy server.
+
+### **6.1.2 NAT and firewall**
+
+A NA(P)T (network address and port translation) and a firewall may be present between the local network and the access network. Since NAT may modify IP addresses and ports, and a firewall restricts access, the signalling and bearer planes need to behave differently when these elements are inserted between the UE and the P-CSCF.
+
+## **6.2 Access network**
+
+The UE connects to the Edge via the existing cable access network or via other available access networks (e.g., public WiFi access point, 3G cellular data network). The access network elements provide the IP connectivity and QoS resources needed by the UE to perform the IPCablecom services.
+
+### **6.2.1 Cable modem (CM)**
+
+The CM is the customer premises equipment (CPE) used in conjunction with the CMTS to provide broadband Internet access service. An E-MTA is an IPCablecom NCS-based client with an embedded cable modem. While the E-MTA does not communicate directly with the network, it is important to note that a NCS-based telephony service and SIP-based service may be provided through the same CM.
+
+### **6.2.2 Cable modem termination system (CMTS)**
+
+The CMTS resides in the cable operators headend, and, in conjunction with the CM, it is used to provide broadband Internet access service. Beginning with ITU-T Rec. J.112, DOCSIS defines a means to provide QoS on the access network. IPCablecom Multimedia defines a means for IP-enabled services to request QoS from the DOCSIS network. IPCablecom defines how QoS can be provided for SIP-based services via IPCablecom multimedia and DOCSIS.
+
+### **6.2.3 Access point**
+
+IP Cablecom may be used to provide service to UEs that receive IP connectivity through other kinds of access networks.
+
+## **6.3 Edge**
+
+### **6.3.1 Proxy call session control function (P-CSCF)**
+
+A UE accesses the SIP Infrastructure through a P-CSCF. The P-CSCF shields the SIP network from access network specific protocol details and provides scaling for the infrastructure by handling
+
+certain resource intensive tasks when interacting with the UE. It also represents the trust boundary for SIP between untrusted parts of the network (Access Network, Local Network) and trusted parts of the network (core, application, interconnect, operational support systems). The functions performed by the P-CSCF are:
+
+- Routing SIP messages from the UE to the I-CSCF or S-CSCF and vice versa.
+- Maintaining security associations between itself and the UE and asserting the identity of authenticated public identities.
+- Interacting with the IPCablecom application manager for QoS management.
+- Providing functionality to allow the UE to traverse NATs and maintain NAT bindings for SIP signalling.
+- Generation of accounting correlation IDs and accounting events.
+
+### 6.3.2 STUN and TURN servers
+
+A STUN server is an entity that receives STUN requests, and sends STUN responses. STUN requests are typically binding requests which are used to determine the bindings allocated by NATs. The UE sends a Binding Request to the server, over UDP. The server examines the source IP address and port of the request, and copies them into a response that is sent back to the UE.
+
+Two STUN servers are employed by the IPCablecom network, one employed as a functional component of the P-CSCF (not shown in Figure 1) and one as a stand-alone STUN server:
+
+- The STUN server as a functional component within the P-CSCF is used by SIP UEs in order to maintain the NAT bindings for signalling. These STUN messages may also act as a keep-alives, allowing the UE to determine P-CSCF availability and detect NAT reboots.
+- The external STUN server shown in Figure 1 is used to determine one of several possible candidate media addresses using the STUN protocol.
+
+In addition to the STUN servers, the architecture also contains a TURN server. A TURN server is an entity that receives TURN requests, and sends TURN responses. The server is capable of acting as a data relay, receiving data on the address it provides to UEs, and forwarding it to the UEs. This data relay functionality allows media to traverse NATs in cases when other NAT traversal techniques are insufficient.
+
+### 6.3.3 IPCablecom application manager
+
+The IPCablecom application manager is responsible for a variety of tasks. Most importantly it is responsible for determining the QoS resources needed for a session based on the received session descriptors and managing the QoS resources allocated for a session.
+
+Determining the QoS resources for a session involves interpreting the session descriptor and calculating the bandwidth necessary, determining the traffic scheduling type and populating the traffic classifiers. This also involves determining the number of flows necessary for the session (voice only vs voice and video) and managing the association of the flows to the session.
+
+## 6.4 Core
+
+### 6.4.1 Serving CSCF (S-CSCF)
+
+All SIP messages outside of a dialog that go to and from a given subscriber pass through the S-CSCF serving that subscriber. At a high level, the S-CSCF supports the following capabilities:
+
+- SIP registrar function, which provides a database that dynamically binds registered public identities (AORs) to a set of contact addresses, assigns GRUUs, as well as stores any other parameters associated with the registration, e.g., user agent capabilities and the address(es) of the P-CSCF which can be used to reach the contacts.
+
+- SIP user authentication and authorization.
+- Service selection and filtering.
+- Routing of messages to the P-CSCF of UEs serviced by the S-CSCF.
+- Routing of messages to an I-CSCF for Public User Identities not serviced by the S-CSCF.
+- Routing of messages to a BGCF for calls to the PSTN.
+- Origination Processing: processing of incoming dialog-initiating requests from SIP UAs contained in UEs or Application Servers served by the S-CSCF.
+- Terminating Processing: processing of outgoing SIP messages terminating to a Public Identity served by the S-CSCF. This includes support for forking of SIP messages for the case in which multiple contact addresses are registered for that Public Identity.
+- External routing queries to databases such as ENUM in order to determine where the call should be routed.
+- Network initiated release of sessions.
+- Generation of Accounting Events.
+
+There may be multiple S-CSCFs in the Core. At any one time, a Subscription (and all the Public Identities associated with it) can only be handled by a single S-CSCF.
+
+Subscriptions are associated with S-CSCFs. Subscription data is stored in one or more home subscriber servers (HSSs). The S-CSCF interacts with the SLF to identify the relevant HSSs to obtain user data for the users it serves. The S-CSCF may also interact with the HSS to store certain types of user data for the users it serves.
+
+GRUUs are supported by the endpoints and the S-CSCF. This allows endpoints to be assigned a GRUU during the registration process, which in turn enables endpoints to initiate a request to a specific contact instead of an AOR. This is important for various features such as call transfer and conferencing.
+
+### 6.4.2 Interrogating CSCF (I-CSCF)
+
+The I-CSCF supports:
+
+- Interacting with the HSS to determine the binding between a subscription (and associated public identities) and a S-CSCF.
+- Querying the HSS to obtain the S-CSCF and then routing SIP requests from another network operator to the correct S-CSCF.
+- Routing of messages to ASs using public service identities (PSIs).
+- Routing of messages to a border element for VoIP peering.
+
+### 6.4.3 Home subscriber server (HSS)
+
+The HSS is responsible for storing the following subscription-related information:
+
+- Association between a subscription and S-CSCF.
+- Subscription profile information (filter criteria).
+- Subscription security information.
+- Transparent or opaque data for usage by application servers.
+
+The HSS provides information storage, retrieval, and processing support to components of the network. It supports the following capabilities:
+
+- Session establishment – The HSS supports the session establishment procedures. For terminating traffic, it provides information on which S-CSCF is assigned to handle a public identity.
+
+- Security – The HSS supports various authentication schemes by storing security-related data and providing this data as required to support UE security procedures.
+- Service Provisioning – The HSS provides access to the service profile data for use by the S-CSCF. The HSS may also store application-specific data for application server.
+
+### 6.4.4 Subscription locator function (SLF)
+
+The SLF provides the name of the HSS containing the required subscriber specific data. The SLF is not needed in a single HSS environment.
+
+## 6.5 IPCablecom multimedia
+
+IP Cablecom multimedia defines an IP-based platform for delivering QoS-enhanced multimedia services over DOCSIS 1.1 (this Recommendation uses DOCSIS and assumes DOCSIS 1.1 or greater) access networks. This platform allows the core capabilities of IPCablecom (e.g., QoS authorization and admission control, event messages for billing and other back-office functions, and security) to support a wide range of IP-based services beyond telephony. That is, while the IPCablecom CMS is customized for the delivery of residential telephony services, the IPCablecom multimedia components offer a general-purpose platform for cable operators to deliver a variety of IP-based multimedia services that require QoS treatment.
+
+The IPCablecom multimedia architecture defines the interaction between a CMTS, policy server, and application manager. The CMTS is included as part of the access network and is described in clause 6.2.2. The application manager is specific to each application. IPCablecom defines an IPCablecom application manager which is described in clause 6.3.3. The policy server, which is a unique IPCablecom multimedia element that may communicate with a variety of application managers, is described below.
+
+### 6.5.1 Policy server
+
+The policy server primarily acts as an intermediary between application manager(s) and CMTS(s). It applies network policies to application manager requests and proxies messages between the application manager and CMTS.
+
+## 6.6 Application
+
+### 6.6.1 Application server (AS)
+
+An application server (AS) provides application-specific services. An AS may influence a SIP session based on its supported services. It may also host and execute services. An AS may initiate services or terminate services on behalf of a user.
+
+### 6.6.2 Presence server
+
+The presence server is a specialized application server. It acts as the focal point for connecting sources of presence information and interested parties.
+
+The presence server can obtain presence information in multiple ways, e.g.:
+
+- Using the SIP PUBLISH method: The PUBLISH request is addressed to a public identity, and then forwarded by the S-CSCF to the presence server in accordance with normal routing rules.
+- Using the SIP SUBSCRIBE method: the presence server may also act as a Watcher, using the SIP SUBSCRIBE method to subscribe to presence information that is available elsewhere, e.g., from a Registrar.
+
+Presence subscriptions by Watchers are addressed to a public identity and delivered by the S-CSCF to the presence server. The presence server manages the dialog for each subscription, and sends a
+
+SIP NOTIFY message to the Watcher(s) each time there is a change in the presence status for which the Watcher is subscribed and authorized.
+
+## **6.7 Interconnect**
+
+### **6.7.1 Border element**
+
+Interconnect with peer networks may be supported through a border element. The border element contains an interconnect proxy function, and may contain a media proxy function.
+
+Interconnect proxy functionality includes:
+
+- Protocol interworking.
+- SIP profile enforcement (translation, adaptation, or normalization).
+- Security-related services (e.g., maintaining a security association with the peer).
+- IP address management (peer networks with the same private IP address space).
+- Interworking between IPv6 and IPv4 networks.
+- Media proxies relay media between peer networks.
+
+IPCablecom does not define specific functional requirements that border elements must support. Instead, it is left to each operator to determine the need for and requirements on a border element.
+
+### **6.7.2 Breakout gateway control function (BGCF)**
+
+The BGCF provides network selection for routing to the PSTN and within its own network determines which MGC is used to connect to the PSTN.
+
+### **6.7.3 Public switched telephone network gateway (PSTN GW)**
+
+The PSTN GW consists of the signalling gateway (SG), media gateway controller (MGC) and the media gateway (MG). The SG, MGC and MG are defined in previous releases of IPCablecom, and are reused in this release of IPCablecom, with the addition of an IPCablecom reference point to the MGC. The SG, MGC and MG are logical components that may exist on separate platforms, or may be combined together onto a single platform.
+
+The SG performs signalling conversion at a transport layer between SS7-based transport and the IP-based transport used in the IPCablecom network. The SG does not interpret the application layer, but does interpret the layers needed for routing signalling messages.
+
+The MGC performs protocol conversion between SS7 ISUP messages and the IPCablecom call control protocols and provides connection control of the media channels in the MG.
+
+The MG provides bearer channel conversion between the circuit switched network and the IP RTP media streams in the IPCablecom network. The MG may introduce codecs and echo cancellers, etc. as needed to provide the bearer channel conversions.
+
+### **6.7.4 Call management server (CMS)**
+
+An IPCablecom call management server (CMS) provides support for telephony services for NCS clients (i.e., E-MTAs). The CMS provides most of the telephony features while interacting directly with application servers (e.g., unified messaging servers and conference servers) to provide additional applications to E-MTAs. It may not allow for features to operate transparently across E-MTAs and UEs owned by the same user.
+
+The IPCablecom CMS communicates with the CSCFs as a peer.
+
+## **6.8 Operational support systems**
+
+The IPCablecom network is expected to have the following servers as part of the operational support system.
+
+### **6.8.1 Dynamic host configuration protocol (DHCP) server**
+
+A DHCP server is used when the UE's local network is under the control of the service provider. It provides IP network participation information (e.g., IP address and DNS server information). UEs in environments that are not under the control of the service provider may not be able to use the services of the service provider's DHCP server. In such cases, it is assumed that the UE receives IP network participation information from the local network.
+
+### **6.8.2 Domain name system (DNS) server**
+
+A DNS server is used to resolve DNS entities (e.g., FQDNs, SRV records) into network addresses and vice versa. A service provider's DNS service is expected to be utilized by UEs and network components alike, for locating entities or routing of messages.
+
+### **6.8.3 ENUM server**
+
+An ENUM server is used to store and translate E.164 numbers to SIP URIs or name server (NS) records pointing to the name server for the operator with delegation for that particular E.164 number. More specifically, an ENUM server uses DNS to identify the owner (service provider or end user) of an E.164 number.
+
+### **6.8.4 Provisioning, activation and configuration (PAC) element**
+
+The PAC element is an IPCablecom-defined component responsible for the provisioning, activation and configuration of UEs. It is responsible for maintaining UE configuration information. The configuration data contains the information necessary for a UE to provide services. It is also the element that conveys runtime configuration changes from the network to the user or vice versa.
+
+The PAC element contains the logical components profile delivery server (PDS) and XCAP data server (XDS) and implements the associated reference points:
+
+- A PDS is the logical collection of the notifier and the server responsible for handling configuration subscription requests.
+- An XDS is as an XCAP server that stores, modifies and retrieves data between UEs and network elements, or between network elements.
+
+### **6.8.5 Element management and network management systems**
+
+An Element management system (EMS) or network management system (NMS) relates to one or more entities associated with monitoring and management of specific network elements or an entire network, respectively.
+
+While EMSs vary in functionality and may differ between network elements, they usually have interfaces to NMSs which are responsible for tracking and maintaining the health of a network.
+
+EMSs and NMSs require management reference points to various elements (e.g., UEs, PAC, application servers, S-CSCF). IPCablecom only defines monitoring and management reference points for UEs.
+
+### **6.8.6 Time server**
+
+A time server is used by UEs to obtain the time.
+
+### **6.8.7 Charging data function (CDF)**
+
+The charging data function (CDF) receives charging events from the various IPCablecom network elements via the IMS defined Rf reference point. It can then use the information contained in the charging events to construct call detail records (CDRs).
+
+Some IPCablecom elements deliver IPCablecom-defined event messages (EMs) to a record keeping server (RKS). The RKS may be used to support a CMS, CMTS, MGC and policy server. However, the RKS is not included in the reference architecture.
+
+# 7 Protocol interfaces and reference points
+
+IPCablecom2 defines a set of protocol interfaces, or reference points, in a number of areas. Many of these reference points are taken directly from the IMS and are enhanced as necessary. Some of the reference points are defined within IPCablecom2. These reference points are identified by their naming convention:
+
+- IMS: Two or three letters (e.g., Gm, ISC);
+- IPCablecom2 defined reference points: pkt-<functional area>-<reference point number>.
+
+Refer to the relevant TRs and specifications for a more complete description and protocol definition.
+
+It is possible that some of these reference points may not exist in a given vendor's product implementation. For example, if several functional IPCablecom2 components are integrated, then it is possible that some of these reference points are internal to the integrated device.
+
+## 7.1 Signalling and service control
+
+IPCablecom2 signalling and service control reference points are illustrated in Figure 4. Most reference points are IMS-defined, with appropriate deviations for IPCablecom as identified in various IPCablecom specifications. IPCablecom-specific reference points are also included.
+
+![Diagram of signalling reference points in IPCablecom2 architecture. The diagram shows various network elements and their interconnections via specific reference points. On the left, a PSTN is connected to a Border element and a PSTN block containing SG, MGC, and MG. The Border element connects to a BGCF via Mx. The PSTN block connects to a BGCF via pkt-sig-2 (from MGC) and pkt-sig-1 (from MG). The BGCF connects to an S-CSCF via Mi. The S-CSCF connects to an AS via ISC, to an I-CSCF via Mw, and to a P-CSCF via Mw. The I-CSCF connects to the P-CSCF via Mw. The P-CSCF connects to a UE via Gm. The CMS connects to the S-CSCF via pkt-sig-2. The AS connects to the I-CSCF via Ma. The I-CSCF connects to the Border element via Mx.](4af57aad638888edf2062306f8a54a6c_img.jpg)
+
+Diagram of signalling reference points in IPCablecom2 architecture. The diagram shows various network elements and their interconnections via specific reference points. On the left, a PSTN is connected to a Border element and a PSTN block containing SG, MGC, and MG. The Border element connects to a BGCF via Mx. The PSTN block connects to a BGCF via pkt-sig-2 (from MGC) and pkt-sig-1 (from MG). The BGCF connects to an S-CSCF via Mi. The S-CSCF connects to an AS via ISC, to an I-CSCF via Mw, and to a P-CSCF via Mw. The I-CSCF connects to the P-CSCF via Mw. The P-CSCF connects to a UE via Gm. The CMS connects to the S-CSCF via pkt-sig-2. The AS connects to the I-CSCF via Ma. The I-CSCF connects to the Border element via Mx.
+
+J.360\_F04
+
+Figure 4 – Signalling reference points
+
+The reference points depicted in Figure 4 are described in Table 2. All reference points are SIP-based except where noted.
+
+**Table 2 – Signalling reference point descriptions**
+
+| Reference point | IPCablecom network elements                                                | Reference point description                                                                                                                                                                                                                                                                                                |
+|-----------------|----------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Mx              | I-CSCF – Border element<br>S-CSCF – Border element                         | Allows an S-CSCF or I-CSCF to communicate with a border element when interworking with another network. For example, a session between the home and peer network could be routed via an IMS ALG function within the border element in order to provide interworking between IPv6 and IPv4 SIP networks.                    |
+| Mi              | S-CSCF – BGCF                                                              | Allows the S-CSCF to forward the session signalling to the BGCF for the purpose of interworking with the PSTN networks.                                                                                                                                                                                                    |
+| Mk              | BGCF – BGCF                                                                | Allows one BGCF to forward the session signalling to another BGCF.                                                                                                                                                                                                                                                         |
+| Mw              | P-CSCF – I-CSCF<br>P-CSCF – S-CSCF<br>I-CSCF – S-CSCF<br>S-CSCF – S-CSCF   | Allows the communication and forwarding of signalling messaging among CSCFs in support of registration and session control. It also allows the CMS to exchange SIP messages with the S-CSCF and I-CSCF for calls between E-MTAs and UEs.                                                                                   |
+| Ma              | I-CSCF – AS                                                                | Allows the I-CSCF to forward SIP requests destined to a public service identity hosted by an application server directly to the application server.                                                                                                                                                                        |
+| ISC             | S-CSCF – AS                                                                | Allows an S-CSCF to communicate with an AS in support of various applications.                                                                                                                                                                                                                                             |
+| Gm              | UE – P-CSCF                                                                | Allows the UE to communicate with the P-CSCF for registration and session control.                                                                                                                                                                                                                                         |
+| pkt-sig-1       | MGC – MG                                                                   | Trunking gateway control protocol (TGCP) interface as defined in the IPCablecom TGCP Specification [ITU-T J.171.1].                                                                                                                                                                                                        |
+| pkt-sig-2       | CMS – S-CSCF<br>CMS – I-CSCF<br>MGC – BGCF<br>MGC – S-CSCF<br>MGC – I-CSCF | CMSS protocol as defined in the IPCablecom CMS to CMS Signalling Specification [ITU-T J.178]. Allows IPCablecom E-MTAs to establish voice sessions with IPCablecom elements. Also allows the BGCF, I-CSCF, and S-CSCF to exchange session signalling with an IPCablecom MGC for the purpose of interworking with the PSTN. |
+
+Refer to the IPCablecom2 SIP signalling overview (Appendix I) for more information.
+
+## 7.2 Subscriber data
+
+IPCablecom subscriber data is stored in the HSS located within the home network. The HSS serves the S-CSCF, I-CSCF, and various application servers including the presence server. The appropriate HSS for a given subscriber can be located by querying the SLF.
+
+Figure 5 illustrates the reference points related to subscriber data services.
+
+![Diagram of subscriber data reference points showing HSS, I-CSCF, S-CSCF, Application server, and SLF with their interconnections labeled Cx, Sh, Dx, and Dh. HSS is at the top, connected to I-CSCF, S-CSCF, and Application server via Cx and Sh interfaces. I-CSCF, S-CSCF, and Application server are connected to SLF via Dx and Dh interfaces. S-CSCF is also connected to HSS via Cx and to SLF via Dx.](11edb7fcedf09ac6a817f8d7b8c61eec_img.jpg)
+
+```
+
+graph TD
+    HSS[HSS] -- Cx --> I_CSCF[I-CSCF]
+    HSS -- Cx --> S_CSCF[S-CSCF]
+    HSS -- Sh --> AS[Application server]
+    I_CSCF -- Dx --> SLF[SLF]
+    S_CSCF -- Dx --> SLF
+    AS -- Dh --> SLF
+  
+```
+
+Diagram of subscriber data reference points showing HSS, I-CSCF, S-CSCF, Application server, and SLF with their interconnections labeled Cx, Sh, Dx, and Dh. HSS is at the top, connected to I-CSCF, S-CSCF, and Application server via Cx and Sh interfaces. I-CSCF, S-CSCF, and Application server are connected to SLF via Dx and Dh interfaces. S-CSCF is also connected to HSS via Cx and to SLF via Dx.
+
+**Figure 5 – Subscriber data reference points**
+
+The reference points depicted in Figure 5 are described in Table 3.
+
+**Table 3 – Subscriber data reference point descriptions**
+
+| Reference point | IPCablecom network elements  | Reference point description                                                                                                                                                       |
+|-----------------|------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Cx              | I-CSCF – HSS<br>S-CSCF – HSS | Allows an I-CSCF and S-CSCF to fetch from the HSS information related to routing, authorization and authentication, subscriber profile and S-CSCF assignment.                     |
+| Sh              | AS – HSS                     | Allows an AS to communicate with the HSS in support of various applications.                                                                                                      |
+| Dx              | I-CSCF – SLF<br>S-CSCF – SLF | Allows an I-CSCF and S-CSCF to fetch the address of the HSS which hosts the subscription data for a given user. This reference point is not required in a single HSS environment. |
+| Dh              | AS – SLF                     | Allows an AS to fetch the address of the HSS which hosts the subscription data for a given user. This reference point is not required in a single HSS environment.                |
+
+Refer to the IPCablecom HSS Overview (Appendix IV) for more information.
+
+## 7.3 Quality of service
+
+The quality of service approach for IPCablecom2 is based on IPCablecom multimedia. In the original IPCablecom multimedia architecture, all service control domain functions were lumped into a single entity called the application manager (AM), of which there can be many. The IPCablecom2 architecture resolves this domain into more discrete elements with defined reference points. For the purposes of providing quality of service, an application manager (AM) serves as the interface between the IPCablecom SIP architecture and the IPCablecom multimedia architecture. Its function is to receive QoS messages from the P-CSCF and to formulate appropriate messages to the IPCablecom multimedia policy server. While this AM function could be integrated into an IPCablecom multimedia policy server, it should be considered as a separate function since it has
+
+unique requirements separate from those of the policy server, such as the resolution of a single session based QoS request into a series of individual QoS requests for each IP flow. The IPCablecom version of the AM is the IPCablecom application manager (PAM).
+
+Figure 6 illustrates the relationship between the application manager, the P-CSCF and the IPCablecom multimedia policy server. Note also that the application manager shown here as a distinct function may be packaged along with an IPCablecom multimedia policy server or, alternatively, with a P-CSCF.
+
+![Diagram of QoS reference points showing connections between PDF, P-CSCF, IPCablecom application manager, Policy server, CM, CMTS, UE, and GPRS network. Reference points include Gq, pkt-qos-1, pkt-mm-3, pkt-mm-2, pkt-qos-2, pkt-mm-1, and Gm.](dcf37c460c66ec011dbe6ca08de44ff9_img.jpg)
+
+```
+
+    graph TD
+      PDF[PDF] -- Gq --> P-CSCF[P-CSCF]
+      P-CSCF -- pkt-qos-1 --> AM[IPCablecom application manager]
+      AM -- pkt-mm-3 --> PS[Policy server]
+      PS -- pkt-mm-2 --> CMTS[CMTS]
+      CMTS -- pkt-mm-1 --> CM[CM]
+      CM --> UE[UE]
+      UE -- Gm --> P-CSCF
+      P-CSCF --> GPRS((GPRS network))
+      GPRS --> PDF
+      PS -- pkt-qos-2 --> CMTS
+  
+```
+
+Diagram of QoS reference points showing connections between PDF, P-CSCF, IPCablecom application manager, Policy server, CM, CMTS, UE, and GPRS network. Reference points include Gq, pkt-qos-1, pkt-mm-3, pkt-mm-2, pkt-qos-2, pkt-mm-1, and Gm.
+
+**Figure 6 – QoS reference points**
+
+As illustrated in Figure 6, the AM function provides the mapping between the session or dialog QoS requirements as indicated by the SIP signalling and the QoS state of each of the associated IP service flows in the cable access network.
+
+The reference points shown in Figure 6 are described in Table 4.
+
+**Table 4 – QoS reference point descriptions**
+
+| Reference point | IPCablecom network elements  | Reference point description                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
+|-----------------|------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Gm              | UE – P-CSCF                  | Refer to Table 2.                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
+| pkt-qos-1       | P-CSCF – Application manager | This is the IPCablecom multimedia web service interface, which enables the P-CSCF to make QoS-related service requests to the application manager, which in turn maps these service requests to policy requests via the pkt-mm-3 reference point. The QoS-related service requests are derived by the P-CSCF from the SIP messages carrying appropriate session descriptions. This reference point is defined in the IPCablecom application manager interface specification [ITU-T J.365]. |
+| pkt-qos-2       | Policy server – CMTS         | The policy server uses the control point discovery protocol [ITU-T J.362] to determine the serving CMTS in the network for a given UE.                                                                                                                                                                                                                                                                                                                                                     |
+
+**Table 4 – QoS reference point descriptions**
+
+| Reference point | IPCablecom network elements         | Reference point description                                                                                                                                                        |
+|-----------------|-------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| pkt-mm-1        | CM – CMTS                           | The CMTS instructs the CM to set up, tear down or change a DOCSIS service flow via DSx signalling. This reference point is defined in IPCablecom Multimedia [ITU-T J.179 App.I].   |
+| pkt-mm-2        | Policy server – CMTS                | Policy decisions are pushed by the policy server onto the CMTS, and the CMTS provides responses. This reference point is defined in IPCablecom multimedia [ITU-T J.179 App.I].     |
+| pkt-mm-3        | Application manager – Policy server | Allows the application manager to request the policy server to install policy decisions on the CMTS. This reference point is defined in IPCablecom multimedia [ITU-T J.179 App.I]. |
+
+Refer to the IPCablecom2 QoS Overview (Appendix II) for more information.
+
+## 7.4 Network address translation (NAT) and firewall traversal
+
+Network address translators (NATs) manipulate address and port information in the IP and transport header. This causes challenges to UEs in communicating with each other using SIP:
+
+- The UE advertises addresses required for media communications in SIP signalling (i.e., SDP). However, the local address available to the UE located behind a NAT may not be reachable by other UEs and network components.
+- NAT/firewall devices contain rules that may vary in terms of how the firewall can be traversed as well as how the NAT bindings are created (i.e., address independent mapping/filtering, address dependent mapping/filtering, or address and port dependent mapping/filtering).
+- Once communication is established, the NAT/firewall maintains state (i.e., firewall pin-holes and NAT bindings) based on timeouts. If the timeout expires, pin-holes are closed and NAT bindings are removed. Mechanisms have to be in place in order to maintain NAT bindings and keep pin-holes open for both signalling and media communications.
+
+The objectives of the NAT/firewall traversal solution are to provide a mechanism by which a UE can:
+
+- Obtain and advertise (e.g., via SDP) a reachable address. For cases, where multiple reachable addresses are possible, a "best" reachable address should be agreed upon.
+- Provide a means to open and maintain pin-holes and NAT bindings for both media and signalling.
+
+IPCablecom2 uses the ICE methodology to obtain and advertise the "best" reachable address and meet the design goals. This methodology makes use of STUN and TURN in order to obtain candidate addresses. These candidate addresses are then advertised by the UE using SDP attributes described in the ICE methodology. The UE then uses STUN to perform reachability tests, allowing it to pick the best address that uses the least network resources and results in the least network delay while maintaining the state in the UE (rather than in the network). It also allows for interworking with E-MTAs, since the address advertised in the media or connection lines of the SDP will always be a reachable address.
+
+The IPCablecom2 NAT and Firewall Traversal Overview (Appendix V) provides additional details on the ICE methodology including a description of how UEs locate STUN and TURN servers. It also describes how NAT bindings are opened and maintained.
+
+Note that one of the design goals is to provide a NAT and firewall traversal mechanism that works regardless of where NATs are located and whether or not they are nested. However, this may not be possible in all cases.
+
+Figure 7 shows the reference points related to NAT/firewall traversal.
+
+![Figure 7: NAT and FW traversal reference points diagram. The diagram shows a UE connected to a NAT & FW. The NAT & FW has three interfaces: X1:x1, X2:x2, and X3:x3. The UE has two interfaces: A1:a1 and A2:a2. The NAT & FW is connected to a P-CSCF via the Gm reference point. The P-CSCF is connected to an S-CSCF via the Mw reference point. The P-CSCF is also connected to an IPCablecom application manager, which is connected to a Policy server, which is connected to a CMTS. The CMTS is connected to a TURN server via the Z1:z1 reference point. The TURN server is connected to a STUN server via the Z2:z2 reference point. The NAT & FW is also connected to a STUN server via the pkt-nat-2 reference point. The NAT & FW is also connected to the CMTS via the pkt-nat-1 reference point.](318886a86a1dcc59e1fc83db6f157c60_img.jpg)
+
+Figure 7: NAT and FW traversal reference points diagram. The diagram shows a UE connected to a NAT & FW. The NAT & FW has three interfaces: X1:x1, X2:x2, and X3:x3. The UE has two interfaces: A1:a1 and A2:a2. The NAT & FW is connected to a P-CSCF via the Gm reference point. The P-CSCF is connected to an S-CSCF via the Mw reference point. The P-CSCF is also connected to an IPCablecom application manager, which is connected to a Policy server, which is connected to a CMTS. The CMTS is connected to a TURN server via the Z1:z1 reference point. The TURN server is connected to a STUN server via the Z2:z2 reference point. The NAT & FW is also connected to a STUN server via the pkt-nat-2 reference point. The NAT & FW is also connected to the CMTS via the pkt-nat-1 reference point.
+
+**Figure 7 – NAT and FW traversal reference points**
+
+The reference points depicted in Figure 7 are described in Table 5.
+
+**Table 5 – NAT and FW traversal reference point descriptions**
+
+| Reference point | IPCablecom network elements | Reference point description                                                                                                           |
+|-----------------|-----------------------------|---------------------------------------------------------------------------------------------------------------------------------------|
+| Gm              | UE – P-CSCF                 | Refer to Table 2.                                                                                                                     |
+| Mw              | P-CSCF – S-CSCF             | Refer to Table 2.                                                                                                                     |
+| pkt-nat-1       | UE – TURN server            | Allows the UE to access a TURN server in order to support the traversal of the NAT that does not perform Address Independent Mapping. |
+| pkt-nat-2       | UE – External STUN server   | Enables the UE to determine one of several possible candidate media addresses using STUN, in support of the ICE methodology.          |
+
+Refer to the IPCablecom NAT and firewall traversal overview (Appendix V) for more information.
+
+## 7.5 Media coding and transport
+
+IPCablecom2 uses RTP to transport most communication services (primarily voice and video). The primary media flows in the IPCablecom2 architecture are shown in Figure 8.
+
+![Figure 8 – Media stream reference points. A diagram showing various network elements connected to a central UE (User Equipment). The elements include a Border element (with Interconnect proxy and Media proxy) connected to a Peer network, a PSTN GW (with SG, MGC, and MG) connected to a PSTN, and an E-MTA. All these elements have 'Mb' reference points connecting them to the central UE. The UE also has 'Mb' reference points connecting it to an Application server (with a Media server) and another UE.](cfb98c691c1af5befe32ff9442eea511_img.jpg)
+
+Figure 8 – Media stream reference points. A diagram showing various network elements connected to a central UE (User Equipment). The elements include a Border element (with Interconnect proxy and Media proxy) connected to a Peer network, a PSTN GW (with SG, MGC, and MG) connected to a PSTN, and an E-MTA. All these elements have 'Mb' reference points connecting them to the central UE. The UE also has 'Mb' reference points connecting it to an Application server (with a Media server) and another UE.
+
+J.360\_F08
+
+**Figure 8 – Media stream reference points**
+
+The reference points depicted in Figure 8 are described in Table 6.
+
+**Table 6 – Media stream reference point descriptions**
+
+| Reference point | IPCablecom network elements                                        | Reference point description                                                                                                                                                                |
+|-----------------|--------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Mb              | UE – UE<br>UE – MG<br>UE – Border element<br>UE – AS<br>UE – E-MTA | Allows media-capable components to send and receive media data packets. Specifically, a UE can exchange media with another UE, a MG, an application server, a border element and an E-MTA. |
+
+The media that travels across the Mb reference point can be the audio traffic encoded narrow-band or wideband audio codecs, the video traffic encoded by video codecs, or the combination of both traffic types. The media may also be data in support of fax relay, modem relay, and DTMF relay.
+
+Audio quality monitoring on the Mb reference points is supported by RTCP. Metrics for video streams are not specified.
+
+Refer to the IPCablecom audio/video codecs specification [ITU-T J.361] for more information.
+
+## 7.6 Provisioning, activation, configuration and management
+
+IPCablecom2 defines a provisioning, activation, configuration and management (PACM) framework to aid the core business processes. The framework includes standard elements (e.g., DHCP), protocols (e.g., XCAP) and IPCablecom specific network elements (e.g., PAC).
+
+Further, the PACM framework is separated into the following areas and sub-areas:
+
+- Provisioning.
+- IP network participation (connectivity to the local network).
+- Service provider identification.
+- Provisioning flows.
+- Support for branded (i.e., tied to a specific operator) and unbranded (i.e., will work with any operator) models.
+- UE Activation, Configuration and Management Framework.
+- UE, Subscriber and Service Activation.
+- UE Configuration and Management Framework.
+- Data model.
+- Transport protocols.
+
+Figure 9 illustrates reference points associated with PACM.
+
+![Diagram of PACM reference points showing a central UE connected to various network elements: PAC (PDS and XDS), DNS, DHCP, Time, and EMS & NMS via reference points pkt-pacm-1 through pkt-pacm-6.](6e15fc9ea763541c5913d26f85072ae1_img.jpg)
+
+The diagram shows a central 'UE' (User Equipment) block connected to five external entities via reference points:
+ 
+
+- 'DHCP' is connected to the left of 'UE' via 'pkt-pacm-1'.
+- 'DNS' is connected to the top-left of 'UE' via 'pkt-pacm-2'.
+- 'PAC' (containing sub-blocks 'PDS' and 'XDS') is connected to the top of 'UE' via 'pkt-pacm-3' (from PDS) and 'pkt-pacm-4' (from XDS).
+- 'Time' is connected to the top-right of 'UE' via 'pkt-pacm-5'.
+- 'EMS & NMS' is connected to the right of 'UE' via 'pkt-pacm-6'.
+
+ A small label 'J:360\_F09' is present in the bottom right corner of the diagram area.
+
+Diagram of PACM reference points showing a central UE connected to various network elements: PAC (PDS and XDS), DNS, DHCP, Time, and EMS & NMS via reference points pkt-pacm-1 through pkt-pacm-6.
+
+**Figure 9 – PACM reference points**
+
+The reference points depicted in Figure 9 are described in Table 7.
+
+**Table 7 – PACM reference point descriptions**
+
+| Reference point | IPCablecom network elements | Reference point description                                                                                                                                                                                              |
+|-----------------|-----------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| pkt-pacm-1      | UE – DHCP                   | Provides network participation information (e.g., IP address, DNS server addresses). This reference point may be provided by the local network, or by an access network not operated by the IPCablecom service provider. |
+| pkt-pacm-2      | UE – DNS                    | Allows the UE to resolve DNS names for location of network elements or routing of messages.                                                                                                                              |
+
+**Table 7 – PACM reference point descriptions**
+
+| Reference point | IPCablecom network elements | Reference point description                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
+|-----------------|-----------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| pkt-pacm-3      | UE – PDS                    | <p>Through the use of SIP, this reference point enables UEs to subscribe to the status of configuration and feature data.</p> <p>This is a generic reference point that describes the interaction between the UE and the XDS. However, in reality, the PDS interacts with the rest of the SIP components as an application server. Therefore, PACM SIP messages will traverse the Gm, Ma, Mw and ISC interfaces.</p> <p>NOTE 1 – The PDS described here is used specifically for PACM. However, as a logical component it may be defined for use in other applications as well.</p> |
+| pkt-pacm-4      | UE – XDS                    | <p>This reference point is used to distribute and manage configuration and feature data.</p> <p>NOTE 2 – The XDS described here is used specifically for PACM. However, as a logical component it may be defined for use in other applications as well.</p>                                                                                                                                                                                                                                                                                                                         |
+| pkt-pacm-5      | UE-Time                     | Allows UEs to obtain the time.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
+| pkt-pacm-6      | UE – EMS & NMS              | Enables EMSs and NMSs to monitor and manage UEs.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
+
+Refer to the IPCablecom2 provisioning, activation, configuration and management specification [ITU-T J.364] for more information.
+
+## 7.7 Network accounting and usage
+
+The IMS defines reference points that allow it to support different types of IMS connectivity access networks (CANs). IPCablecom2 Accounting assumes the Cable HFC access network along with the IPCablecom multimedia subsystem define a new type of IP-CAN for incorporation into the overall IMS architecture.
+
+Figure 10 shows the main IPCablecom components involved with offline charging and the reference points between each of the components.
+
+![Figure 10 – Accounting reference points. A network diagram showing various nodes and their connections. Nodes include AS, S-CSCF, P-CSCF, UE, CDF, Application manager, CM, Policy server, CMTS, Billing system, and RKS. Reference points are labeled: ISC (AS to S-CSCF), Rf (AS to CDF, S-CSCF to CDF, P-CSCF to CDF), Mw (S-CSCF to P-CSCF), pkt-qos-1 (P-CSCF to Application manager), Gm (P-CSCF to UE), pkt-mm-1 (CM to CMTS), pkt-mm-2 (Policy server to CMTS), pkt-mm-3 (Application manager to Policy server), pkt-mm-4 (Policy server to RKS), and pkt-mm-5 (CMTS to RKS). There are also 'Undefined' connections between CDF and Billing system, and between Billing system and RKS. A label 'J.360_F10' is in the bottom right corner.](f57c7b37d7a05a99618104f390089f03_img.jpg)
+
+Figure 10 – Accounting reference points. A network diagram showing various nodes and their connections. Nodes include AS, S-CSCF, P-CSCF, UE, CDF, Application manager, CM, Policy server, CMTS, Billing system, and RKS. Reference points are labeled: ISC (AS to S-CSCF), Rf (AS to CDF, S-CSCF to CDF, P-CSCF to CDF), Mw (S-CSCF to P-CSCF), pkt-qos-1 (P-CSCF to Application manager), Gm (P-CSCF to UE), pkt-mm-1 (CM to CMTS), pkt-mm-2 (Policy server to CMTS), pkt-mm-3 (Application manager to Policy server), pkt-mm-4 (Policy server to RKS), and pkt-mm-5 (CMTS to RKS). There are also 'Undefined' connections between CDF and Billing system, and between Billing system and RKS. A label 'J.360\_F10' is in the bottom right corner.
+
+**Figure 10 – Accounting reference points**
+
+The reference points depicted in Figure 10 are described in Table 8.
+
+**Table 8 – Accounting reference point descriptions**
+
+| Reference point | IP Cablecom network elements        | Reference point description                                                                                                                                     |
+|-----------------|-------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Gm              | UE – P-CSCF                         | Refer to Table 2.                                                                                                                                               |
+| Mw              | P-CSCF – S-CSCF                     | Refer to Table 2.                                                                                                                                               |
+| ISC             | S-CSCF – AS                         | Refer to Table 2.                                                                                                                                               |
+| Rf              | CSCF – CDF                          | DIAMETER-based reference point from between the IMS nodes (P-CSCF, S-CSCF, and AS) to the charging data function (CDF).                                         |
+| pkt-qos-1       | P-CSCF – Application manager        | Refer to Table 4.                                                                                                                                               |
+| pkt-mm-1        | CM – CMTS                           | Refer to Table 4.                                                                                                                                               |
+| pkt-mm-2        | Policy server – CMTS                | Refer to Table 4.                                                                                                                                               |
+| pkt-mm-3        | Application manager – Policy server | Refer to Table 4.                                                                                                                                               |
+| pkt-mm-4        | PS – RKS                            | RADIUS-based reference point between the PS and the record keeping server (RKS). This reference point is defined in IP Cablecom multimedia [ITU-T J.179 App.I]. |
+| pkt-mm-5        | CMTS – RKS                          | RADIUS-based reference point between the CMTS and the RKS. This reference point is defined in IP Cablecom multimedia [ITU-T J.179 App.I].                       |
+
+Refer to the IPCablecom accounting specification [ITU-T J.363] for more information.
+
+## 7.8 Security
+
+The IPCablecom2 security architecture documents the security requirements reference points across the entire architecture. For the purpose of organizing the security reference points, three different trust domains have been defined.
+
+- Intra-Network Domain – Reference points in this domain connect network elements within a service provider's domain.
+- Inter-Network Domain – Reference points in this domain connect two domains. The domains can be different service providers, or the same provider.
+- Access Domain – Reference points in this domain allow UEs to connect to a service provider.
+
+These trust domains are used to decompose the IPCablecom architecture.
+
+Refer to the IPCablecom2 Security Overview (Appendix III) for more information.
+
+### 7.8.1 Access domain security
+
+![Diagram of Access domain reference points showing the flow of traffic from User Equipment (UE) through various network functions (NAT, PACM, Signalling, Media) to external servers (TURN, STUN, DHCP, DNS, PDS, XDS, Time, EMS & NMS, P-CSCF, Media server, Application server).](896e86ed12aff206d302c64f2e3091fa_img.jpg)
+
+The diagram illustrates the 'Access domain' architecture. On the left, two 'UE' (User Equipment) blocks are connected by a vertical line labeled 'Mb'. This connection leads into a central vertical stack of four main functional blocks, each containing specific reference points:
+
+- NAT**: Contains 'pkt-nat-1' and 'pkt-nat-2'. To its right are 'TURN server' and 'STUN server'.
+- PACM**: Contains 'pkt-pacm-1' through 'pkt-pacm-6'. To its right are 'DHCP', 'DNS', a group containing 'PDS' and 'XDS' (labeled 'PAC'), 'Time', and 'EMS & NMS'.
+- Signalling**: Contains 'Gm'. To its right is 'P-CSCF'.
+- Media**: Contains 'Mb'. To its right are 'Media server' and 'Application server'.
+
+A thick vertical line runs through the center of the four functional blocks, representing the main data path. The label 'Access domain' is at the top. The identifier 'J.360\_F11' is at the bottom right.
+
+Diagram of Access domain reference points showing the flow of traffic from User Equipment (UE) through various network functions (NAT, PACM, Signalling, Media) to external servers (TURN, STUN, DHCP, DNS, PDS, XDS, Time, EMS & NMS, P-CSCF, Media server, Application server).
+
+Figure 11 – Access domain reference points
+
+UE interactions with the network occur in the access domain. Access methods are varied, and include DOCSIS and wireless. Due to these characteristics, the access domain is home to a multitude of threats, as described in Appendix III. Table 9 provides a high-level overview of how the access domain reference points are secured.
+
+**Table 9 – Access domain reference point descriptions**
+
+| Reference point | IPCablecom network elements                                        | Reference point description                                                                                                  |
+|-----------------|--------------------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------|
+| pkt-nat-1       | UE – TURN server                                                   | TURN: TURN requests are authenticated and authorized within the TURN protocol itself.                                        |
+| pkt-nat-2       | UE – External STUN server                                          | STUN: Message integrity is provided by STUN mechanisms.                                                                      |
+| pkt-pacm-1      | UE – DHCP server                                                   | DHCP: IPCablecom does not define security for the DHCP protocol.                                                             |
+| pkt-pacm-2      | UE – DNS server                                                    | DNS: IPCablecom does not define security for the DNS protocol.                                                               |
+| pkt-pacm-3      | UE – PDS server                                                    | SIP: Message integrity and privacy via Internet Protocol Security (IPSec) or transport layer security (TLS).                 |
+| pkt-pacm-4      | UE – XDS server                                                    | XCAP: Message integrity and privacy via HTTP over TLS.                                                                       |
+| pkt-pacm-5      | UE – Time server                                                   | SNTP: IPCablecom does not define security for the SNTP protocol.                                                             |
+| pkt-pacm-6      | UE – EMS & NMS server                                              | Management interface security is out of scope for this Specification.                                                        |
+| Gm              | UE – P-CSCF                                                        | SIP: Message integrity and privacy via IPSec or TLS.<br>STUN: Message integrity is provided by STUN mechanisms.              |
+| Mb              | UE – UE<br>UE – MG<br>UE – Border element<br>UE – AS<br>UE – E-MTA | RTP: Media security is out of scope for this Specification.<br>NOTE – Figure 11 only shows a few representative media flows. |
+
+### 7.8.2 Intra-network domain security
+
+Intra-network domain reference points and components are contained within a service provider's network, and consequently, a holistic security policy. These reference points are generally secured using the Zb reference point. The Zb reference point uses IPSec encapsulating security payload (ESP). Zb reference points that support TCP may also use TLS.
+
+The following Intra-domain reference points define additional security requirements that may be applied in addition to, or in place of, the Zb reference point:
+
+- pkt-qos-2 – Cryptographic challenge mechanism defined by the control point discovery protocol.
+- pkt-laes-4 – Cryptographic mechanisms defined by SNMPv3.
+- pkt-laes-6 – Cryptographic challenge mechanism defined by the control point discovery protocol.
+
+### 7.8.3 Inter-network domain security
+
+The inter-network domain reference points consist of:
+
+- Border element – Peer network – Secured using the Za reference point, which uses IPSec ESP. Inter-domain traffic in the IMS is required to pass through a security gateway (SEG). The SEG supports the Za reference point and enforces security policy on inter-domain traffic flows. It is assumed that the border element includes the SEG functionality, but the SEG may be a separate element.
+- PSTN gateway – PSTN – PSTN security is not defined.
+- CMS – Endpoints – Security for the CMS reference point is defined in the IPCablecom security specification [ITU-T J.170].
+
+## 7.9 Lawful intercept
+
+The IPCablecom2 lawful intercept architecture is illustrated in Figure 12. IPCablecom call control elements, such as the CSCFs, form the set of potential call related data intercept access points. IPCablecom bearer plane elements, such as the CMTS and MG, form the set of potential call content intercept access points. The delivery function (DF) receives intercepted call related events and call content from the IPCablecom intercept access points, correlates them to a target subscriber service, and then delivers the result to the law agency collection function (CF) over a standard reference point defined by [ES-DCI]. Note that the DF is not part of the IPCablecom architecture, although IPCablecom specifies reference points to the DF needed for the lawful interception with IPCablecom networks. Call control elements such as the S-CSCF and P-CSCF assigned to a target subscriber report call related events to the DF. These control elements also dynamically provision peer elements for intercept during call redirects and third party call control scenarios. Border elements, such as the BGCF, I-CSCF and MGC report interconnection carrier information to the DF. The DF provisions the call content intercept access points by first discovering the access points via the control point discovery protocol and then provisioning intercept on the content access points with SNMPv3. The call content provisioning process is initiated when the DF first receives a call initiation event from the call control elements.
+
+The IPCablecom CMS is upgraded to interoperate with IPCablecom elements to support the interception of calls across NCS and SIP components. The IPCablecom MGC and MG elements may, as an option, be upgraded for the IPCablecom reference points in Figure 12.
+
+![Diagram of lawful intercept reference points showing various network elements connected to a central Delivery function.](9a5927586a691c4908aa2cf98bd47ebb_img.jpg)
+
+The diagram illustrates the lawful intercept reference points (pkt-laes-1 through pkt-laes-6) in a network architecture. A central 'Delivery function' block is connected to several other blocks representing different network elements or functions:
+
+- Top block:** 'Call-related data intercept access points: Application server, BGCF, CMS, I-CSCF, MGC, P-CSCF, S-CSCF'. It is connected to the Delivery function via 'pkt-laes-2' and to 'pkt-laes-3' via a line.
+- Left block:** 'Call-related data intercept access points: Application server, BGCF, CMS, I-CSCF, MGC, P-CSCF, S-CSCF'. It is connected to the Delivery function via 'pkt-laes-2'.
+- Bottom-left block:** 'Call content intercept access points: Aggregation router, CMTS, Media server, MG'. It is connected to the Delivery function via 'pkt-laes-4', 'pkt-laes-5', and 'pkt-laes-6'.
+- Right block:** 'Collection function'. It is connected to the Delivery function via 'pkt-laes-1'.
+
+Diagram of lawful intercept reference points showing various network elements connected to a central Delivery function.
+
+J.360\_F12
+
+**Figure 12 – Lawful intercept reference points**
+
+The reference points depicted in Figure 12 are described in Table 10.
+
+**Table 10 – Lawful intercept reference point descriptions**
+
+| Reference point | IPCablecom network elements                       | Reference point description                                                                                                                                                                                                                               |
+|-----------------|---------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| pkt-laes-1      | DF – CF                                           | Correlated call related data and call content are reported to the law agency collection function. Defined in [ES-DCI].                                                                                                                                    |
+| pkt-laes-2      | Session control element – DF                      | Intercept call related events are reported to the DF. This reference point is DIAMETER based.                                                                                                                                                             |
+| pkt-laes-3      | Session control element – Session control element | Allows session control elements to dynamically provision intercept in peer elements for calls where the targeted subject's assigned control elements are no longer involved in the call. Call redirect is one example. This reference point is SIP based. |
+| pkt-laes-4      | DF to content access points                       | The DF dynamically provisions content intercept points. This reference point is SNMPv3 based.                                                                                                                                                             |
+| pkt-laes-5      | Content access point to DF                        | Intercepted call content is reported to the DF. This reference point is media over UDP based.                                                                                                                                                             |
+| pkt-laes-6      | DF to content access points                       | The DF, as the Requestor, uses the control point discovery protocol [ITU-T J.362] to determine the appropriate call content IAPs, acting as control points, in the network for call content intercept.                                                    |
+
+Refer to the IPCablecom electronic surveillance – Intra-network functions specification [ES-INF] and the IPCablecom electronic surveillance – Delivery function to collection function interface specification [ES-DCI] for more information.
+
+### 7.10 Control point discovery
+
+The control point discovery reference point, shown in Figure 13, defines a network-based protocol that can be used to find the IP address needed in order to make requests for QoS as well as for content tapping for the purposes of lawful intercept (LI).
+
+For QoS requests, this applies to finding the IP address of the CMTS for DQoS and IPCablecom multimedia (PCMM). For LI it applies to discovering the IP address to use for content tapping at the CMTS as well as media gateways and aggregation routers/switches in front of media endpoints. In addition to providing the IP address, the response indicates the protocol to use and can also indicate the subnet that the requested destination address is contained within.
+
+![Figure 13 – Control point discovery reference point](8d5d12ba8fe7313bc891241275c64d20_img.jpg)
+
+```
+
+  graph LR
+    Requestor[Requestor] -- pkt-cpd-1 --> CP[Control point]
+    Endpoint[Endpoint] --- CP
+    CP --- MS[Media stream]
+  
+```
+
+**Figure 13 – Control point discovery reference point**
+
+Figure 13 – Control point discovery reference point
+
+The reference points depicted in Figure 13 are described in Table 11.
+
+**Table 11 – Control point discovery reference point description**
+
+| Reference point | IPCablecom network elements | Reference point description                                                                                                                                                                                     |
+|-----------------|-----------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| pkt-cpd-1       | Requestor – Control point   | The requestor uses the control point discovery protocol to determine the appropriate control point in the network for a given UE. Other reference points in the architecture are based on this reference point. |
+
+Refer to the IPCablecom2 Control Point Discovery Specification [ITU-T J.362] for more information.
+
+36 ITU-T Rec. J.360 (11/2006)
+
+# Appendix I
+
+# SIP signalling overview
+
+(This appendix does not form an integral part of this Recommendation)
+
+## I.1 Introduction and purpose
+
+This appendix provides an overview of the SIP signalling architecture and describes the high-level requirements to support SIP communications within the IPCablecom2 architecture.
+
+The primary focus of this appendix is to define how the IPCablecom2 functional elements involved in session signalling communicate based on the IETF SIP protocol and extensions, and to specify the enhancements made to 3GPP IMS.
+
+Since IPCablecom2 SIP signalling is closely aligned with IMS, the IPCablecom2 SIP signalling normative requirements are defined in IMS Delta specifications, which are 3GPP specifications enhanced to accommodate cable-specific requirements. The IPCablecom2 SIP signalling requirements are documented in three IMS Delta specifications, ITU-T Recs J.366.2, J.366.3 and [ITU-T J.366.4].
+
+### I.1.1 Relationship to IPCablecom features and services
+
+This appendix and its associated IMS Delta specifications serve as a SIP signalling foundation for support of a wide variety of IP-based communication services, ranging from legacy telephony features to new and enhanced communication applications and services. This SIP signalling base is service independent; and, therefore, requirements specific to each IPCablecom service and feature are out-of-scope for this appendix, and are defined separately. The relationship between this appendix, the base SIP signalling IMS Delta specifications, and the IPCablecom features and services is shown in Figure I.1.
+
+![Diagram illustrating the relationship between base SIP signalling and services. The diagram is divided into two main horizontal layers. The top layer, labeled 'Service-dependent SIP signalling', contains three boxes: 'Residential SIP telephony', 'Wireless and cellular integration', and 'Other services'. The bottom layer, labeled 'Base (service-independent) SIP signalling', contains a box for 'SIP signalling (this Recommendation)' and a sub-box for 'IMS-delta specifications' which includes three boxes: 'J.366.2', 'J.366.3', and 'J.366.4'. Arrows point from the bottom layer to the top layer, indicating that the base signalling supports the services. A label 'Cellular' is on the left side of the top layer. A small label 'J.360_F1.1' is in the bottom right corner.](0908107b858fa3783d10d93b3a3444b2_img.jpg)
+
+The diagram illustrates the relationship between base SIP signalling and services. It is structured as follows:
+
+- Top Layer: Service-dependent SIP signalling**
+  - Contains three boxes: **Residential SIP telephony**, **Wireless and cellular integration**, and **Other services**.
+  - A label **Cellular** is positioned to the left of this layer.
+- Bottom Layer: Base (service-independent) SIP signalling**
+  - Contains a box for **SIP signalling (this Recommendation)**.
+  - Contains a sub-box for **IMS-delta specifications**, which includes three boxes: **J.366.2**, **J.366.3**, and **J.366.4**.
+- Relationship:** Arrows point from the bottom layer to the top layer, indicating that the base signalling supports the services.
+- Small label:** J.360\_F1.1
+
+Diagram illustrating the relationship between base SIP signalling and services. The diagram is divided into two main horizontal layers. The top layer, labeled 'Service-dependent SIP signalling', contains three boxes: 'Residential SIP telephony', 'Wireless and cellular integration', and 'Other services'. The bottom layer, labeled 'Base (service-independent) SIP signalling', contains a box for 'SIP signalling (this Recommendation)' and a sub-box for 'IMS-delta specifications' which includes three boxes: 'J.366.2', 'J.366.3', and 'J.366.4'. Arrows point from the bottom layer to the top layer, indicating that the base signalling supports the services. A label 'Cellular' is on the left side of the top layer. A small label 'J.360\_F1.1' is in the bottom right corner.
+
+Figure I.1 – Relationship between base SIP signalling and services
+
+### I.1.2 Relationship to other IPCablecom2 specifications
+
+The IPCablecom2 base SIP signalling specifications together define the signalling requirements for the following general capabilities:
+
+- SIP message routing.
+- Registration.
+- Media session establishment.
+- Event-Notification framework.
+- Generic service control platform.
+- Identity assertion.
+
+Other IPCablecom2 specifications such as accounting, NAT traversal, and security, place additional requirements on SIP signalling; and therefore, impact the same IMS Delta specifications, specifically [ITU-T J.366.4]. Also, certain SIP signalling mechanisms impact non-SIP IMS Delta specifications such as [ITU-T J.366.5]. Finally, IPCablecom2 SIP signalling places requirements on [ITU-T J.178] to support IPCablecom2 UE to IPCablecom E-MTA interworking. The relationship among these various specifications is shown in Figure I.2.
+
+![Figure I.2 – SIP signalling specification relationships. This diagram illustrates the relationships between various specifications. On the left, 'Previous IPCablecom Recommendations' include 'J.160-J.178'. The central 'IPCablecom2 SIP signalling' box contains 'SIP signalling (this Recommendation)' which has arrows pointing to '3GPP 23.218 IM call model stage 2', 'J.366.4 3GPP 24.229 SIP stage 3', and 'J.366.3 3GPP 23.228 IMS stage 2'. These three are grouped under 'SIP IMS-delta specifications'. On the right, 'Other IPCablecom2 Recommendations' include 'Accounting', 'Security', and 'Codec and media'. 'Codec and media' points to 'Other IMS-delta specifications', which include 'J.366.5 3GPP 29.228 Cx and Dx interfaces'. Arrows (1) through (6) show dependencies: (1) from SIP signalling to 3GPP 23.218; (2) from SIP signalling to J.366.4; (3) from SIP signalling to J.366.3; (4) from J.160-J.178 to SIP signalling; (5) from SIP signalling to Codec and media; (6) from SIP signalling to Other IMS-delta specifications.](cf8bd014a50b7c69435e804f67f9617f_img.jpg)
+
+Figure I.2 – SIP signalling specification relationships. This diagram illustrates the relationships between various specifications. On the left, 'Previous IPCablecom Recommendations' include 'J.160-J.178'. The central 'IPCablecom2 SIP signalling' box contains 'SIP signalling (this Recommendation)' which has arrows pointing to '3GPP 23.218 IM call model stage 2', 'J.366.4 3GPP 24.229 SIP stage 3', and 'J.366.3 3GPP 23.228 IMS stage 2'. These three are grouped under 'SIP IMS-delta specifications'. On the right, 'Other IPCablecom2 Recommendations' include 'Accounting', 'Security', and 'Codec and media'. 'Codec and media' points to 'Other IMS-delta specifications', which include 'J.366.5 3GPP 29.228 Cx and Dx interfaces'. Arrows (1) through (6) show dependencies: (1) from SIP signalling to 3GPP 23.218; (2) from SIP signalling to J.366.4; (3) from SIP signalling to J.366.3; (4) from J.160-J.178 to SIP signalling; (5) from SIP signalling to Codec and media; (6) from SIP signalling to Other IMS-delta specifications.
+
+Figure I.2 – SIP signalling specification relationships
+
+## I.2 References
+
+This appendix uses the following additional informative references.
+
+- [ITU-T J.366.4] ITU-T Recommendation J.366.4 (2006), *IPCablecom2 IP Multimedia Subsystem (IMS): Session Initiation Protocol (SIP) and Session Description Protocol (SDP) – Stage 3 specification*. (3GPP TS 24.229)
+- [ITU-T J.366.5] ITU-T Recommendation J.366.5 (2007), *IP multimedia (IM) subsystem Cx and Dx interfaces; signalling flows and message contents specification*. (3GPP TS 29.228)
+
+- [IETF RFC 3261] IETF RFC 3261 (2002), *SIP: Session Initiation Protocol*.
+- [IETF RFC 3262] IETF RFC 3262 (2002), *Reliability of Provisional Responses in the Session Initiation Protocol (SIP)*.
+- [IETF RFC 3311] IETF RFC 3311 (2002), *The Session Initiation Protocol (SIP) UPDATE Method*.
+- [IETF RFC 3312] IETF RFC 3312 (2002), *Integration of Resource Management and Session Initiation Protocol (SIP)*.
+- [IETF RFC 3320] IETF RFC 3320 (2003), *Signaling Compression (SigComp)*.
+- [IETF RFC 3329] IETF RFC 3329 (2003), *Security Mechanism Agreement for the Session Initiation Protocol (SIP)*.
+- [IETF RFC 3455] IETF RFC 3455 (2003), *Private Header (P-Header) Extensions to the Session Initiation Protocol (SIP) for the 3rd-Generation Partnership Project (3GPP)*.
+- [IETF RFC 3486] IETF RFC 3486 (2003), *Compressing the Session Initiation Protocol (SIP)*.
+- [IETF RFC 3556] IETF RFC 3556 (2003), *Session Description Protocol (SDP) Bandwidth Modifiers for RTP Control Protocol (RTCP) Bandwidth*.
+- [IETF RFC 3680] IETF RFC 3680 (2004), *A Session Initiation Protocol (SIP) Event Package for Registrations*.
+- [IETF RFC 4032] IETF RFC 4032 (2005), *Update to the Session Initiation Protocol (SIP) Preconditions Framework*.
+
+## 1.3 Terms and definitions
+
+This appendix uses the following additional terms and definitions:
+
+**1.3.1 authorized identity:** An instance of an 'Authorized Identity' in an IPCablecom2 network is a representation of an allowed pairing between a Private Identity and a Public Identity.
+
+**1.3.2 core:** The core contains the basic components required to provide SIP services and subscriber data. The core functional grouping consists of the following functional components: Interrogating-CSCF (I-CSCF), serving-CSCF (S-CSCF), subscription locator function (SLF), and home subscriber server (HSS).
+
+**1.3.3 identity credentials:** A collection of the information needed to perform authentication of a private identity. The actual information depends on the authentication mechanism.
+
+**1.3.4 IPCablecom2 service provider:** A network operator, operating one or more independent IPCablecom2 Administrative Domains.
+
+**1.3.5 IPCablecom2 service provider DNS domain:** A DNS domain name that is owned and managed by an IPCablecom2 administrative domain. It is used to form SIP URIs that convey public identifiers.
+
+**1.3.6 proxy server:** An intermediary SIP entity that acts as both a server and a UE for the purpose of making requests on behalf of other UEs. A proxy server primarily plays the role of routing, which means its job is to ensure that a request is sent to another entity "closer" to the targeted user. Proxies are also useful for enforcing policy (for example, making sure a user is allowed to make a call). A proxy interprets, and, if necessary, rewrites specific parts of a request message before forwarding it.
+
+**1.3.7 public identifier:** An identifier used to reference a public identity.
+
+### I.4 Abbreviations and acronyms
+
+This appendix uses the following additional abbreviation:
+
+SIP UE User equipment that contains a SIP user agent
+
+### I.5 IPCablecom2 SIP signalling
+
+IPCablecom2 applications and services are controlled using session initiation protocol (SIP). IPCablecom2 aligns with a specific instance of the SIP architecture as defined by the IP multimedia subsystem (IMS) specifications being developed by the 3rd generation partnership project (3GPP). IPCablecom2 is based on Release 6 of IMS, and enhances IMS where necessary to support IPCablecom2 requirements.
+
+#### I.5.1 IPCablecom2 SIP signalling architecture and reference points
+
+IPCablecom2 signalling and service control reference points are illustrated in Figure I.3. Most reference points are IMS-standard, with appropriate deviations for IPCablecom2 as identified in various IPCablecom2 specifications. IPCablecom2-specific reference points are also included.
+
+![Figure I.3 – Call signalling reference points](930335a43c8196e391f87e6860db4d45_img.jpg)
+
+```
+
+    graph TD
+    BE[Border element] -- Mx --> BGCF1[BGCF]
+    BE -- Mx --> ICSCF[I-CSCF]
+    BGCF1 -- Mk --> BGCF2[BGCF]
+    BGCF2 -- Mi --> SCSCF[S-CSCF]
+    BGCF2 -- pkt-sig-2 --> PSTN_MGC[MGC]
+    SCSCF -- Mw --> ICSCF
+    SCSCF -- ISC --> AS[AS]
+    AS -- Ma --> ICSCF
+    ICSCF -- Mw --> PCSCF[P-CSCF]
+    SCSCF -- Mw --> PCSCF
+    PCSCF -- Gm --> UE[UE]
+    CMS[CMS] -- pkt-sig-2 --> SCSCF
+    CMS -- pkt-sig-2 --> PCSCF
+    PSTN_SG[SG] -- PSTN --> PSTN_EXT[PSTN]
+    PSTN_MGC -- pkt-sig-1 --> PSTN_MG[MG]
+    PSTN_MGC -- pkt-sig-2 --> SCSCF
+    PSTN_MG -- pkt-sig-2 --> PCSCF
+  
+```
+
+Detailed description: A network diagram showing the interconnection of various SIP functional entities. The Border element connects via Mx to BGCF and I-CSCF. BGCF connects to another BGCF via Mk, which then connects to S-CSCF via Mi. The S-CSCF connects to I-CSCF and P-CSCF via Mw, and to an Application Server (AS) via ISC. The AS connects to I-CSCF via Ma. The P-CSCF connects to the User Equipment (UE) via Gm. A Call Management Server (CMS) connects to S-CSCF and P-CSCF via pkt-sig-2. A PSTN gateway block contains SG, MGC, and MG; MGC connects to BGCF and S-CSCF via pkt-sig-2, and to MG via pkt-sig-1. MG connects to P-CSCF via pkt-sig-2.
+
+Figure I.3 – Call signalling reference points
+
+**Figure I.3 – Call signalling reference points**
+
+#### I.5.1.1 SIP signalling functional components
+
+##### I.5.1.1.1 User equipment (UE)
+
+IPCablecom2 supports SIP clients with a variety of forms and capabilities, e.g., soft and hard phones, smart phones, wireless and wired phones, instant messaging applications, video communications terminals, etc. Consistent with IMS, IPCablecom2 clients are called user equipment (UE). All of the various UEs use the same basic infrastructure to obtain multimedia
+
+40
+
+ITU-T Rec. J.360 (11/2006)
+
+services. UEs may be fixed or mobile devices such as laptops or WiFi-enabled phones. They may reside on the cable access network, or they may obtain services from other access networks.
+
+##### **1.5.1.1.2 Proxy call session control function (P-CSCF)**
+
+A UE accesses the SIP Infrastructure through a P-CSCF. The P-CSCF shields the SIP network from access network specific protocol details, and provides scaling for the infrastructure by handling resource intensive tasks when interacting with the UE. It also represents the trust boundary for SIP between untrusted parts of the network (access network, local network), and trusted parts of the network (core, application, interconnect, operational support). The P-CSCF provides the following functions:
+
+- Routes SIP messages from the UE to the I-CSCF or S-CSCF and vice versa.
+- Maintains security associations between itself and the UE and asserts the identity of authenticated public identities.
+- Tracks the registration status of public identities, and removes security association with the UE when a public identity is deregistered by the network.
+- Verifies the incoming messages data (e.g., verify the SIP route header).
+- Blocks service (e.g., ignores certain incoming requests from unregistered public identities).
+- Enforces policy (e.g., whether signalling security or compression is enabled or disabled).
+- Generates accounting events.
+
+##### **1.5.1.1.3 Serving SCSF (S-CSCF)**
+
+The S-CSCF is responsible for providing services to UE-based subscribers. The S-CSCF does not, however, provide services to IPCablecom E-MTAs. Rather, E-MTAs are served by their CMS as described in [ITU-T J.160].
+
+All SIP messages outside of a dialog that go to and from a given subscriber will pass through the S-CSCF serving that subscriber. At a high level, the S-CSCF provides:
+
+- SIP registrar function, which maintains data that dynamically binds registered public identifiers (AORs) to a set of contact addresses, assigns globally routable user agent URIs, as well as stores any other parameters associated with the registration; e.g., user agent capabilities and the address(es) of the P-CSCF which can be used to reach the contacts, distributes user registration status to entities that subscribe to the Reg-Event package.
+- SIP user authentication and authorization.
+- Service control platform: Applies filter criteria to incoming dialog initiating requests, and based on service point triggers, routes requests to appropriate application servers to provide features and services.
+- Routing of SIP messages to a P-CSCF for UEs served by the S-CSCF.
+- Routing of SIP messages to an I-CSCF for public user identities not serviced by the S-CSCF.
+- Routing of messages to a BGCF for calls to the PSTN.
+- Routing of messages to a peer I-CSCF for calls to a peer network.
+- Routing of messages to the home I-CSCF THIG for topology hiding for calls to a peer network.
+- Origination processing: Processing of incoming dialog-initiating requests from SIP UAs contained in UEs or application servers served by the S-CSCF.
+- Terminating processing: Processing of outgoing SIP messages terminating to a public identifier served by the S-CSCF. This includes support for forking of SIP messages for the case in which multiple contact addresses are registered for that public identifier.
+
+- May query external routing databases such as ENUM, local number portability (LNP) and 800 number databases in order to determine where the call should be routed.
+- Generation of accounting events.
+- Monitoring the health of active sessions, and releasing sessions if a component in the signalling path fails (for example, the S-CSCF can release active sessions associated with, and on behalf of a failed UE).
+- Network initiated release of sessions (e.g., due to administrative activity).
+
+There may be multiple S-CSCFs in the IPCablecom core. At any one time, a subscription (and all the public identifiers associated with it) can only be handled by a single S-CSCF.
+
+Public identifiers are assigned to an S-CSCF at registration time. Once a public identifier is assigned to an S-CSCF, all other registered instances of that public identifier must be assigned to the same S-CSCF. Also all public identifiers in the same subscription must be associated with the same S-CSCF. Subscription data is stored in one or more home subscriber server(s) (HSS). The S-CSCF interacts with the relevant HSSs to obtain user data for the users it serves. The S-CSCF may also interact with the HSS to store certain types of user data for the users it serves.
+
+Globally routable user agent URI (GRUU) are supported by the endpoints and the S-CSCF. This allows endpoints to be assigned a globally routable URI during the registration process, which in turn enables endpoints to initiate a request to a specific contact instead of an AOR. This is important for various features such as call transfer and conferencing.
+
+##### **I.5.1.1.4 Interrogating CSCF (I-CSCF)**
+
+The I-CSCF is responsible for routing incoming requests to the correct terminating S-CSCF. It also provides a topology hiding interworking gateway function (THIG) that can be used to hide the internal topology of the home network from a peer network, or from a home UE.
+
+- Routes incoming REGISTER messages received from the P-CSCF to the correct S-CSCF.
+- Routes incoming dialog-initiating requests received from an originating S-CSCF in the home network or originating S-CSCF in a peer network to the correct terminating S-CSCF.
+- Generation of accounting events.
+
+The I-CSCF is the routing point in the network for external requests from other networks that are destined for users in the home network. It communicates with the HSS to determine the binding between a Subscription (and associated public identities) and an S-CSCF.
+
+##### **I.5.1.1.5 Application server (AS)**
+
+An AS provides value-added IPCablecom services and resides in either the user's home network or in a third party location, which could be another network or a stand-alone AS. An AS may influence a SIP session on behalf of its supported services and it may host and execute services. An AS may initiate services or terminate services on behalf of a user.
+
+##### **I.5.1.1.6 Border element**
+
+Interconnect with peer networks may be supported through a border element. The border element contains an interconnect proxy function, and may contain a media proxy function. The border element can provide a variety of functions:
+
+- Protocol interworking.
+- SIP profile enforcement (translation, adaptation, or normalization).
+- Security-related services (e.g., maintaining a security association with the peer).
+- IP address management (peer networks with the same private IP address space).
+- Interworking between IPv6 and IPv4 networks.
+
+- Media relay between peer networks (e.g., for media security or codec interworking).
+- Address and topology hiding at the signalling level (e.g., acts as a signalling relay and provides obfuscation of address information in headers).
+
+##### **I.5.1.1.7 Breakout gateway control function (BGCF)**
+
+The BGCF provides network selection for routing to the PSTN and within its own network determines which MGC is used to connect to the PSTN. The BGCF may query external routing databases to determine where the call should be routed.
+
+##### **I.5.1.1.8 Public switched telephone network gateway (PSTN GW)**
+
+The PSTN GW consists of the signalling gateway (SG), media gateway controller (MGC) and the media gateway (MG). The SG, MGC and MG functional elements are defined in previous releases of IPCablecom, and are reused in this release of IPCablecom2, with the addition of an IPCablecom2 reference point to the MGC. The SG, MGC and MG are logical components that may exist on separate platforms, or may be combined together onto a single platform.
+
+The SG performs signalling conversion at a transport layer between SS7-based transport and the IP-based transport used in the IPCablecom network. The SG does not interpret the application layer, but does interpret the layers needed for routing signalling messages.
+
+The MGC performs protocol conversion between SS7 ISUP messages and the IPCablecom call control protocols and provides connection control of the media channels in the MG.
+
+The MG provides bearer channel conversion between the circuit switched network and the IP RTP media streams in the IPCablecom network. The MG may introduce codecs and echo cancellers, etc. as needed to provide the bearer channel conversions.
+
+##### **I.5.1.1.9 Call management server (CMS)**
+
+An IPCablecom call management server (CMS) provides support for telephony services for NCS clients (i.e., E-MTAs). In IPCablecom2 the CMS provides most of the telephony features while, interacting directly with application servers (unified messaging servers, conference servers, etc.) to provide additional applications to NCS endpoints. It does not allow, however, for features to operate transparently across E-MTAs and UEs owned by the same user.
+
+#### **I.5.1.2 SIP signalling reference points**
+
+The reference points depicted in Figure I.3 are described in Table I.1. All reference points are SIP-based except where noted.
+
+**Table I.1 – Call signalling reference points**
+
+| <b>Reference point</b> | <b>IPCablecom2 network elements</b>                | <b>Reference point description</b>                                                                                                                                                                                                                                                                      |
+|------------------------|----------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Mx                     | I-CSCF – Border element<br>S-CSCF – Border element | Allows an S-CSCF or I-CSCF to communicate with a border element when interworking with another network. For example, a session between the home and peer network could be routed via an IMS ALG function within the border element in order to provide interworking between IPv6 and IPv4 SIP networks. |
+| Mi                     | S-CSCF – BGCF                                      | Allows the S-CSCF to forward the session signalling to the BGCF for the purpose of interworking with the PSTN networks.                                                                                                                                                                                 |
+| Mk                     | BGCF – BGCF                                        | Allows one BGCF to forward the session signalling to another BGCF.                                                                                                                                                                                                                                      |
+
+**Table I.1 – Call signalling reference points**
+
+| Reference point | IPCablecom2 network elements                                               | Reference point description                                                                                                                                                                                                                                                   |
+|-----------------|----------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Mw              | P-CSCF – I-CSCF<br>P-CSCF – S-CSCF<br>I-CSCF – S-CSCF<br>S-CSCF – S-CSCF   | Allows the communication and forwarding of signalling messaging among CSCFs in support of registration and session control.                                                                                                                                                   |
+| Ma              | I-CSCF – AS                                                                | Allows the I-CSCF to forward SIP requests destined to a public service identity hosted by an application server directly to the application server.                                                                                                                           |
+| ISC             | S-CSCF – AS                                                                | Allows an S-CSCF to communicate with an AS in support of various applications.                                                                                                                                                                                                |
+| Gm              | UE – P-CSCF                                                                | Allows the UE to communicate with the P-CSCF for registration and session control.                                                                                                                                                                                            |
+| pkt-sig-1       | MGC – MG                                                                   | Trunking gateway control protocol (TGCP) interface as defined in the IPCablecom TGCP specification [ITU-T J.171.1].                                                                                                                                                           |
+| pkt-sig-2       | CMS – S-CSCF<br>CMS – I-CSCF<br>MGC – BGCF<br>MGC – S-CSCF<br>MGC – I-CSCF | Allows the S-CSCF and I-CSCF to exchange session signalling with the CMS to enable IPCablecom E-MTAs to establish voice sessions with UEs. Also allows the BGCF, I-CSCF and S-CSCF to exchange session signalling with the MGC for the purpose of interworking with the PSTN. |
+
+### I.5.2 IPCablecom2 enhancements to IMS
+
+While many of the components and interfaces defined in the IMS have broad applicability in other industries, Release 6 of the IMS is still a wireless-centric architecture, designed to meet the business and operational needs of the wireless industry. Therefore it does not meet all of the needs of the cable industry. IPCablecom2 enhances IMS to support the unique technology requirements of the cable industry, and also addresses cable operator business and operating requirements.
+
+3GPP is developing newer releases of the IMS specifications. Future updates to IPCablecom2 will align with these newer releases as necessary.
+
+#### I.5.2.1 Cable broadband access
+
+Radio access is typically limited by scarce resources and high latency. Therefore, IMS mandates support of special mechanisms and SIP extensions to mitigate these limitations. Since cable broadband access does not have the bandwidth resource or latency limitations typical of radio access, support of these capabilities is made optional for IPCablecom2.
+
+UE support of the following SIP extensions, which is mandatory for IMS Release 6, is made optional for IPCablecom2.
+
+##### I.5.2.1.1 Bandwidth modifiers for RTCP
+
+[IETF RFC 3556] adds SDP attributes to enable a UE to explicitly specify the maximum RTCP bandwidth it wishes to receive from the remote UE. This enables an IMS UE to reduce its radio access resource usage by specifying a low (may be zero) RTCP bandwidth value. For IPCablecom2, support of the RTCP bandwidth modifiers is optional at the UE. If the UE supports this extension, then it must honour the RTCP bandwidth attributes when received in order to support interworking with IMS UEs that use these parameters. Also, the UE must be able to send the RTCP bandwidth modifiers based on a locally configured value (the configured value may be based on the type of access network).
+
+##### **I.5.2.1.2 P-Associated-URI**
+
+[IETF RFC 3455] defines a P-Associated-URI header that is used as part of implicit registration to inform the UE of the multiple public identities in the implicit registration set. This reduces the registration message traffic, since multiple public identities can be registered with a single transaction. For IPCablecom2, support of P-Associated-URI header is optional at the UE.
+
+##### **I.5.2.1.3 SIP compression**
+
+[IETF RFC 3486] provides a SIP message compression capability that reduces signalling bandwidth usage and latency on the radio access network. Support of SIP compression at the UE is optional for IPCablecom2. The P-CSCF controls whether SIP compression is enabled or not, based on locally configured data, or on the access network type reported in the P-network-access-info header.
+
+##### **I.5.2.1.4 SIP timers**
+
+IMS modifies (lengthens) the SIP message timing intervals to reduce the signalling load on the access network, and to tolerate the increased latency of radio access. For IPCablecom2, the UE must conform to the standard SIP timing intervals specified in [IETF RFC 3261].
+
+#### **I.5.2.2 Modularity**
+
+IPCablecom2 is required to support modularity at the UE, to promote interworking with non-3GPP SIP endpoints, and to enable operators to tune deployments to specific service offerings. Therefore, some of the SIP extensions that are mandated by IMS Release 6 are made optional for IPCablecom2.
+
+##### **I.5.2.2.1 Reliable provisional response**
+
+[IETF RFC 3262] defines a SIP request called PRACK that is used to enable early 2-way media and to ensure reliable delivery of provisional responses. For IPCablecom2, support of PRACK is mandatory at the UE, and its use must be configurable to one of the following two modes:
+
+- 1) Required – The UE must include option tag "100rel" in SIP Require header of the INVITE request, so that it is able to establish sessions only with other UEs that also support PRACK.
+- 2) Negotiated – The UE must include option tag "100rel" in the SIP Supported header of the INVITE request so that it can negotiate whether PRACK is actually used or not based on whether or not it is also supported by the remote UE.
+
+##### **I.5.2.2.2 Update**
+
+[IETF RFC 3311] defines a SIP request called UPDATE that is used to update media sessions before answer (primarily for preconditions). Support of UPDATE in IPCablecom2 is mandatory at the UE (i.e., UE must always advertise in Allow header), but optional to use. For example, the UE can choose not to send UPDATE if it knows the remote UE does not support it based on what was received in the incoming Allow header.
+
+##### **I.5.2.2.3 Reg event package**
+
+[IETF RFC 3680] defines a new event package called Reg-Event that is used by the network to inform the UE that it has been de-registered. The network can use this event package to block a UE from gaining access to network services, or to trigger a UE to re-register for S-CSCF re-assignment. For IPCablecom2, support of the Reg event package is optional at the UE. If supported, the UE must provide configuration controls to disable its use.
+
+##### **I.5.2.2.4 P-access-network-info header**
+
+[IETF RFC 3455] defines a SIP header called P-access-network-info which enables the UE to inform the network of the access technology (e.g., radio, 802.11, DOCSIS). For IPCablecom2,
+
+support of the P-Access-Network-Info is optional at the UE. If this header is supported, then the UE will report P-Access-Network-Info only if it knows the type access technology that it is using. For example, an embedded MTA may know that its network access is over DOCSIS, while a soft client may not know whether its access is over DOCSIS or WiFi.
+
+##### **1.5.2.2.5 Disabling signalling security**
+
+IP Cablecom2 mandates support of signalling security for both the UE and the P-CSCF. However, the P-CSCF must support configuration parameters that enable signalling security between the UE and P-CSCF to be disabled. The P-CSCF must support three modes that apply to all UE signalling associations with the P-CSCF:
+
+- 1) Signalling security off – Signalling security is always off across all UEs served by the P-CSCF.
+- 2) Signalling security on – Signalling security is enabled for all UEs served by the P-CSCF.
+- 3) Signalling security negotiated – Signalling security is on for UEs that support it (note that signalling security support is mandatory for IP Cablecom2 UEs), and off for UEs that do not support it.
+
+#### **1.5.2.3 Services**
+
+The base IP Cablecom2 architecture needs to support some additional basic capabilities required by services such as residential SIP telephony and wireless and cellular integration that are not supported in IMS Release 6.
+
+##### **1.5.2.3.1 Tel URI number portability and carrier routing**
+
+For IP Cablecom2, support of number portability is optional for the S-CSCF and mandatory for the MGC. The BGCF may support addition of a network-wide pre-subscribed carrier. Support of these parameters is optional for the UE. Note that a UE that supports the Tel URI must support these parameters as well.
+
+##### **1.5.2.3.2 Globally routable user agent URI (GRUU)**
+
+GRUU defines a mechanism whereby a registrar can provide a globally routable contact address to a registering user agent. This is required by certain features such as call-transfer that require the ability to route a dialog-initiating request to a specific registered instance of an AOR, when multiple registered instances exist. For IP Cablecom2, support of GRUU is optional at the UE, but mandatory for the network components that are impacted by GRUU (e.g., S-CSCF). A UE that supports GRUU must resort to using the AOR as a contact address when interworking with remote UEs that do not support GRUU.
+
+##### **1.5.2.3.3 Internet-draft – GRUU Reg-event package**
+
+Implicit registration enables multiple public identities to register under a single REGISTER transaction. The response to REGISTER can carry only a single GRUU URI. Therefore, when both GRUU and implicit registration are supported, there needs to be a way to communicate multiple GRUUs to the UE. This is accomplished using an extension to the Reg event package that enables multiple GRUU URIs to be communicated in a NOTIFY to the Reg event package.
+
+## **I.6 IP Cablecom2 IMS requirements**
+
+This clause describes the requirements that are currently not supported in IMS Release 6, but that are needed in the IP Cablecom2 SIP signalling architecture.
+
+### **I.6.1 SIP secure signalling**
+
+IP Cablecom2 allows signalling security to be disabled between the UE and the P-CSCF. This clause first outlines the signalling security model defined in 3GPP for IMS communications and then
+
+describes the impacts to IMS for allowing access to IMS-services without secure SIP signalling between the UE and P-CSCF.
+
+#### **I.6.1.1 Description**
+
+The IMS security architecture [ITU-T J.366.7] is based on several mandatory security relationships, two of which are closely coupled with IMS registration procedures:
+
+- 1) Mutual authentication between the user and network.
+- 2) Security association between the UE and P-CSCF, which provides integrity protection and optional confidentiality protection of SIP signalling (i.e., signalling security).
+
+According to IMS registration procedures, the UE first sends an initial REGISTER request to the P-CSCF which routes the request to the S-CSCF serving the user. Since a security association has not yet been established between the UE and P-CSCF, the initial REGISTER request is sent unprotected. The S-CSCF determines that the received REGISTER request was sent unprotected by checking the "integrity-protected" parameter in the SIP authorization header. Because the REGISTER request was sent unprotected and the user is not already registered, the S-CSCF initiates the mutual authentication procedures by generating a 401 (Unauthorized) response to the unprotected REGISTER request, and the S-CSCF starts a reg-await-auth timer.
+
+After receiving the 401 (Unauthorized) response, the UE establishes a set of security associations with the P-CSCF. The UE then sends a second REGISTER request containing the authentication challenge response, which is sent protected over the newly established security association and routed to the same S-CSCF. Because the REGISTER request was sent protected and an authorization procedure is ongoing for this user (i.e., a reg-await-auth timer is running for this particular user), the S-CSCF authenticates the user by verifying the authentication challenge response. Once the S-CSCF successfully completes registration procedures, a 200 (OK) response is sent to the UE.
+
+With the exception of an initial REGISTER request, IMS requires all SIP messages to and from the UE to be sent protected over the security association. The security association also provides data origin authentication, which enables the P-CSCF to assert the identity of the UE.
+
+Signalling security is a mandatory capability of the UE in the IPCablecom2 SIP architecture. However, IPCablecom2 allows signalling security to be disabled in the following ways:
+
+- 1) the UE may be configured [ITU-T J.364] to have signalling security disabled; or
+- 2) the P-CSCF may be configured to have signalling security disabled for all UEs that access IMS services through that P-CSCF.
+
+In addition, there are certain requests that may not require signalling security. In IPCablecom2 IMS, the only such request is subscription to the ua-profile event package.
+
+#### **I.6.1.2 Impacted components**
+
+This clause describes the IMS components impacted by allowing access to IMS-services without secure SIP signalling between the UE and P-CSCF, as well as the nature of the impact on the component.
+
+NOTE – Additional security considerations for disabling signalling security are documented in Appendix III.
+
+##### **I.6.1.2.1 UE**
+
+An IPCablecom2 UE must support the negotiation and establishment of security associations as described in IMS. However, while disabling security is not recommended, an IPCablecom2 UE must be flexible to be able to interoperate in an operator environment where signalling security procedures have been disabled.
+
+In IPCablecom2, a security association is not initiated by the UE in the following scenarios:
+
+- The UE receives an indication from the P-CSCF during initial registration that signalling security is disabled.
+- The UE is configured to have signalling security disabled as described in [ITU-T J.364], and the UE has not received an indication from the P-CSCF during initial registration that signalling security is required.
+
+If the UE includes the "sec-agree" option tag in the Require header as defined in [IETF RFC 3329] when sending an initial REGISTER request and a 420 (Bad Extension) response is received with the "sec-agree" option tag value in the Unsupported header, the UE should resend the REGISTER request and not follow the procedures defined in [IETF RFC 3329].
+
+If the UE is configured to have signalling security disabled and the UE has not received a 494 (Security Agreement Required) response, the UE must not follow the procedures described in [IETF RFC 3329].
+
+If the UE successfully registers without having established a security association, then the following applies for any initial request or stand-alone transaction (excluding REGISTER):
+
+- If the UE supports the P-Preferred-Identity header, the UE must insert it and set its value to a registered public user identity of the user.
+- If the UE does not support the P-Preferred-Identity header, the UE shall ensure that the From header field is set to a registered public user identity of the user. In this case, privacy may not be supported.
+
+Subscription requests to the ua-profile event package may be allowed prior to registration, based on local policy. If the UE is not registered, then the following applies for SUBSCRIBE requests to the ua-profile event package:
+
+- The UE must include the From header and set its value to the public user identity derived as described in clause I.6.13: "Routing SUBSCRIBEs for configuration information".
+- If the UE supports the P-Preferred-Identity header, the UE must insert it and set its value to the same public user identity included in the From header field.
+
+##### **I.6.1.2.2 P-CSCF**
+
+In IPCablecom2, the P-CSCF must support signalling security requirements as defined in Appendix III.
+
+The P-CSCF may be configured to have signalling security "disabled" or "required" for all UEs that access IMS-services through that P-CSCF. The P-CSCF may also be configured to have signalling security "optional"; in this case, the P-CSCF determines whether signalling security is disabled for a particular UE based on an indication received from the UE during initial registration.
+
+If the P-CSCF is configured to have signalling security "optional" or "disabled", then the following applies:
+
+- The P-CSCF must accept REGISTER requests that do not contain the "sec-agree" option tag in the Require header as defined in [IETF RFC 3329]. In this case, the P-CSCF must ignore the security mechanism agreement related procedures specified in [ITU-T J.364].
+- The P-CSCF should allow unprotected non-REGISTER requests.
+
+If the P-CSCF is configured to have signalling security "disabled", then the following applies:
+
+- The P-CSCF must accept REGISTER requests that do not contain the "sec-agree" option tag in the Require header as defined in [IETF RFC 3329]. In this case, the P-CSCF must ignore the security mechanism agreement related procedures specified in [ITU-T J.366.4].
+- If the P-CSCF receives a REGISTER request from a UE that includes the "sec-agree" option tag in the Require header as defined in [IETF RFC 3329], the P-CSCF must reject the request with a 420 (Bad Extension) response and include the "sec-agree" option tag in the Unsupported header.
+- The P-CSCF should allow unprotected non-REGISTER requests.
+
+If the P-CSCF is configured to have signalling security "required", then the following applies:
+
+- If the P-CSCF receives a REGISTER request from a UE that does not contain the "sec-agree" option tag in the Require header as defined in [IETF RFC 3329], the P-CSCF shall reject the request with a 494 (Security Agreement Required) response.
+
+The P-CSCF should assert the identity of the request originator (i.e., insert a P-Asserted-Identity header), and remove the P-Preferred-Identity header, if present, only for non-REGISTER requests received over a security association.
+
+If the P-CSCF receives a non-REGISTER request that does not contain a Route header (i.e., a request from an unregistered user), the P-CSCF shall forward the request to the I-CSCF of the served user.
+
+##### **I.6.1.2.3 I-CSCF**
+
+In IPCablecom2, the I-CSCF must support signalling security requirements as defined in Appendix III.
+
+##### **I.6.1.2.4 S-CSCF**
+
+In IPCablecom2, the S-CSCF must support signalling security requirements as defined in Appendix III.
+
+The S-CSCF may be configured to have signalling security "required" for all UEs that access IMS-services through that S-CSCF. The S-CSCF may also be configured to have signalling security "optional"; in this case, the S-CSCF accepts unprotected REGISTER requests that are authenticated. The configuration of the S-CSCF and P-CSCF must be coordinated by the operator.
+
+If the S-CSCF and P-CSCF are configured to allow access to IMS-services without secure SIP signalling for one or more UE, then the following applies:
+
+- If the S-CSCF receives a REGISTER request and authentication is currently ongoing for this user (i.e., the timer reg-await-auth is running), then the S-CSCF shall perform the registration procedures specified in [ITU-T J.366.4] as if the "integrity-protected" parameter in the Authorization header was set to "yes".
+- While performing origination processing for a registered public user identity, if the S-CSCF receives a request that is missing a P-Asserted-Identity header that is otherwise required by [ITU-T J.366.4], then:
+  - The S-CSCF shall identify the originator based on the value contained in the P-Preferred-Identity header, if present, or the From header, if the P-Preferred-Identity header is absent.
+  - If the request contains a valid authentication response, the S-CSCF shall insert a P-Asserted-Identity header and remove the P-Preferred-Identity header, if present.
+  - If the request does not contain a valid authentication response, the S-CSCF should challenge the request by generating a 401 (Unauthorized) response.
+
+If the S-CSCF receives a SUBSCRIBE request to the ua-profile event package from an unregistered but known public user identity, the S-CSCF should perform origination processing as if the user was registered.
+
+#### **I.6.1.3 IPCablecom2 IMS Delta specification**
+
+The following IPCablecom2 IMS Delta specification contains the necessary requirements for SIP secure signalling: [ITU-T J.366.4].
+
+### **I.6.2 Support of IPv4 and IPv6**
+
+#### **I.6.2.1 Description**
+
+[ITU-T J.366.4] specifies that UEs and IMS subsystem entities are assigned IPv6 addresses. As part of the 3GPP IMS Release 7 support for "Fixed Broadband", this is being extended to allow UEs and IMS subsystems to be assigned IPv4 addresses, IPv6 addresses, or both. IPCablecom2 requires IPv4 support and both types of addresses must be supported by IPCablecom2 UEs and IMS components.
+
+Some procedures in [ITU-T J.366.4] are explicitly described as specific to IPv6. Such procedures are not applicable to IPv4 clients (i.e., "Change of IPv6 address due to privacy").
+
+#### **I.6.2.2 Impacted components**
+
+Changes required for support of IPv4 are incorporated into [ITU-T J.366.4]. This 3GPP change request includes the following relevant changes:
+
+- Changes for URI and address assignments, to allow IPv4, IPv6, or both to be assigned to IMS subsystem entities and UEs (clause 4.2 of [ITU-T J.366.4]).
+  - Use of IPv6 in IPCablecom2 is planned for further study. Use of IPv4 only is initially assumed. The change is included per the 3GPP changes.
+- Modifications of the S-CSCF procedures, by generalizing a procedure that checks for an IP address type in SDP, in an error scenario where the far end indicates the address type is not supported (clause 5.4.3.2 of [ITU-T J.366.4]).
+  - Interworking between an IPv4-based IPCablecom2 network and IPv6-based networks is planned for further study, but this change is included to incorporate all related changes from the 3GPP R7 CR.
+  - Modifications of the UE procedures for P-CSCF discovery to references relevant to IPv4 DHCP procedures (clause 9.2.1 of [ITU-T J.366.4]).
+  - This particular change is not relevant to IPCablecom2 since alternate procedures are used for P-CSCF discovery, but it is included to incorporate all related changes from the 3GPP R7 CR.
+
+#### **I.6.2.3 IPCablecom2 IMS Delta specification**
+
+The following IPCablecom2 IMS Delta specification contains the necessary requirements for Support of IPv4 and IPv6: clauses 4.2, 5.4.3.2 and 9.2.1 of [ITU-T J.366.4].
+
+### **I.6.3 SIP compression**
+
+#### **I.6.3.1 Description**
+
+3GPP IMS Release 6 [ITU-T J.366.4] mandates the UE and P-CSCF to support signalling compression (SigComp) as defined in [IETF RFC 3320] and SIP compression as defined in [IETF RFC 3486]. SIP compression is mandated to minimize delays over low bandwidth 3GPP access. For the cable broadband access part of IPCablecom2, this set of considerations does not apply. Note that, as part of the 3GPP IMS Release 7 support for "Fixed Broadband", the support and use of SIP compression is made optional for UEs using broadband access technology, and use
+
+of SIP compression by the P-CSCF (e.g., when supported by the client) is not required if the UE is using broadband access technology.
+
+IPCablecom2 incorporates these 3GPP IMS Release 7 changes for SIP compression: Support for signalling compression (SigComp) as defined in [IETF RFC 3320] and SIP compression as defined in [IETF RFC 3486] is optional for IPCablecom2 UE to implement and for P-CSCF to use.
+
+The implementation of the above requirement is dependent upon the knowledge that the UE is on a cable broadband network using a new value for the access type for the P-Access-Network-Info header, representing DOCSIS broadband access network technology. Refer to clause I.6.12.1.2 for further details.
+
+NOTE – The 3GPP IMS Release 7 solution may be subject to further study within 3GPP to determine if there are better ways to determine access delays and whether SIP compression should be utilized. As such, IPCablecom2 may re-align with any future changes made in this area.
+
+#### **I.6.3.2 Impacted components**
+
+The required changes are identified and incorporated into Release 7.
+
+##### **I.6.3.2.1 UE**
+
+Support of SigComp and SIP compression is optional for UEs that are intended for use on a broadband access network.
+
+If SigComp and SIP compression are supported by the UE, SigComp and SIP compression should not be utilized by the UE if the UE is on a broadband access network (based on access type in P-Access-Network-Info), or the UE is unaware of the access type.
+
+##### **I.6.3.2.2 P-CSCF**
+
+Support of SigComp and SIP compression is required for the P-CSCF deployed in a cable broadband access network but its actual use is optional.
+
+If SigComp is supported by the UE, the use of SIP compression should not be proposed by the P-CSCF if the UE is on a cable broadband access network (based on access type in P-Access-Network-Info), or if the access type is unknown.
+
+#### **I.6.3.3 IPCablecom2 IMS Delta specification**
+
+The following IPCablecom2 IMS Delta specification contains the necessary requirements for SIP compression: Clause 8 of [ITU-T J.366.4].
+
+### **I.6.4 Reliability of SIP provisional responses**
+
+#### **I.6.4.1 Description**
+
+The reliability of provisional response in the SIP protocol is an extension defined in [IETF RFC 3262] in support of multiple applications. First, it is necessary when establishing sessions using the SIP preconditions extension. Secondly, it enables an SDP offer/answer exchange as part of an INVITE request and initial provisional response, which is required to support early media (for example, in certain PSTN interworking scenarios). Finally, it guarantees that the action taken by a UE on receiving a provisional response does in fact occur (e.g., guarantees that an originating UE applies ring-back tone on receiving a 180 response to INVITE).
+
+3GPP IMS Release 6 mandates support of the reliability of provisional responses for the UE when initiating sessions, in support of the SIP preconditions extension. IPCablecom2 will update these requirements to enable the UE, based on configuration data, to interwork with non-3GPP UEs that do not support this SIP extension.
+
+#### **I.6.4.2 Impacted components**
+
+The impacts to enable a UE to interwork with endpoints that do not support the reliable provisional response SIP extension are localized to the UE itself.
+
+##### **I.6.4.2.1 UE**
+
+A UE that supports sessions must support the reliable provisional response extension as defined in [IETF RFC 3262].
+
+A UE can be configured to require support of the reliable provisional response extension. In this case, session establishment with another UE that does not support the same extension will fail.
+
+Alternatively, a UE can be configured to negotiate support of the reliable provisional response extension, so that the extension is used only if it is supported by both the initiating and terminating UE.
+
+#### **I.6.4.3 Impacted IMS Delta specifications**
+
+The following IPCablecom2 IMS Delta specification contains the necessary requirements for reliability of SIP provisional responses:
+
+See clause 5.1 and Table A.4 of [ITU-T J.366.4].
+
+### **I.6.5 SIP UPDATE**
+
+#### **I.6.5.1 Description**
+
+The SIP UPDATE extension method defined in [IETF RFC 3311] allows a SIP client to update the parameters of a session. In particular, it is used in support of SIP preconditions [IETF RFC 3312].
+
+3GPP IMS Release 6 mandates support of the UPDATE method as part of the preconditions extension. IPCablecom2 extends these requirements to enable optional use of UPDATE outside of preconditions. Specifically, an IPCablecom2 UE must support UPDATE, but should adopt procedures to maximize interworking with UEs that do not support UPDATE (e.g., substitute re-INVITE).
+
+#### **I.6.5.2 Impacted components**
+
+The impacts to enable a UE to interwork with endpoints that do not support the SIP UPDATE extension are localized to the UE itself.
+
+##### **I.6.5.2.1 UE**
+
+A UE must support UPDATE for sessions that are established using preconditions.
+
+A UE can also require support of UPDATE for sessions that are established without preconditions. In this case, session establishment with another UE that does not support UPDATE will fail.
+
+Alternatively, a UE can negotiate support of UPDATE for sessions that are established without preconditions, so that the extension is used only if it is supported by both the initiating and terminating UE.
+
+#### **I.6.5.3 IPCablecom2 impacted IMS Delta specifications**
+
+The following IPCablecom2 IMS Delta specification contains the necessary requirements for SIP UPDATE: See clause 5.1 and Table A.4 of [ITU-T J.366.4].
+
+### **I.6.6 SIP preconditions**
+
+#### **I.6.6.1 description**
+
+The support for preconditions in SIP, as defined in [IETF RFC 3312] and updated by [IETF RFC 4032], is an optional feature of the IPCablecom2 signalling architecture. Originally
+
+mandated by IMS, the requirements for SIP preconditions have been relaxed. SIP Preconditions are not mandatory anymore in 3GPP IMS Release 6. The changes will be incorporated in the next version of the IMS Release 6 specifications.
+
+#### **I.6.6.2 Impacted components**
+
+This clause describes the component impacts for optional UE support of the SIP preconditions extension.
+
+##### **I.6.6.2.1 UE**
+
+IP Cablecom2 UEs may support SIP preconditions. If supported, the UE must comply with [IETF RFC 3312] and [IETF RFC 4032].
+
+The IP Cablecom2 UE should negotiate the use of SIP pre-conditions. The UE should indicate its support for SIP preconditions in the appropriate SIP headers (Supported or Require) and it should be flexible in allowing the establishment of sessions with UEs that do not support preconditions. For example, a UE terminating a SIP dialog should include the "precondition" option tag in the Require header if the dialog-initiating request received from the originating UE contained an indication that SIP preconditions is supported with the "preconditions" option tag in the Supported header.
+
+#### **I.6.6.3 IPCablecom2 IMS Delta specification**
+
+The following IPCablecom2 IMS Delta specification contains the necessary requirements for SIP preconditions: See clauses 5.1.3, 5.1.4 and 6.1 of [ITU-T J.366.4].
+
+### **I.6.7 SDP bandwidth modifiers for RTCP**
+
+#### **I.6.7.1 Description**
+
+Standard SDP does not provide a mechanism to explicitly control RTCP bandwidth. Instead, RTCP bandwidth is implicitly fixed at 5% of the session bandwidth. [IETF RFC 3556] introduces two new SDP bandwidth modifiers for RTCP that can be used to explicitly set the RTCP bandwidth to any value independent of the RTP session bandwidth. IMS uses this mechanism to limit the RTCP bandwidth to a value less than 5% (possibly zero) in deployments where radio access is scarce and expensive.
+
+Since cable broadband access does not have the bandwidth resource restrictions of radio, there is no need to limit the RTCP bandwidth below the 5% default within the IPCablecom access network. However, there is value in having an IPCablecom2 UE support these bandwidth modifiers when received from an IMS UE, in order to avoid overrunning the RTCP bandwidth allocation in the IMS radio access network. Therefore, support of the RTCP bandwidth modifiers is made optional for IPCablecom2 UEs.
+
+#### **I.6.7.2 Impacted components**
+
+This clause describes the component impacts for optional UE support of the RTCP bandwidth modifiers.
+
+##### **I.6.7.2.1 UE**
+
+Support of [IETF RFC 3556] is optional for IPCablecom2 UEs deployed in a cable broadband access network.
+
+#### **I.6.7.3 IPCablecom2 IMS Delta specification**
+
+The following IPCablecom2 IMS Delta specification contains the necessary requirements for SDP bandwidth modifiers for RTCP:
+
+See clause 6 of [ITU-T J.366.4].
+
+### **I.6.8 Registration state event package**
+
+The SIP event package for registration-state is an optional function of the IPCablecom2 UE.
+
+#### **I.6.8.1 Description**
+
+When a UE successfully performs initial registration, registration state is created in a SIP registrar (i.e., S-CSCF) for a list of URIs associated with the public user identity that was registered. The list of URIs includes the public user identity that was explicitly registered (unless it is barred), the associated set of implicitly registered public user identities, and possibly other associated public user identities.
+
+The registration state of a URI in the list can change dynamically, for reasons such as:
+
+- Network-initiated deregistration: According to local administrator policy, the network may deregister a public user identity. This might occur, for example, due to non-payment of bills.
+- Network-initiated re-authentication: According to local administrator policy, the network may reduce the expiry time for a current registration, in order to force the UE to re-authenticate. This might occur, for example, when fraud is detected.
+- Registration from multiple devices: The contact addresses bound to any URI in the list can change, due to registrations from other devices.
+
+According to IMS registration procedures, the UE is required to subscribe to registration-state information after successful initial registration, and to maintain the subscription until all URIs in the list become deregistered. This subscription enables the SIP registrar to notify the UE of events such as changes to registration state (i.e., "active" to "terminated"), shortening of registration expiry timers, and modifications to contact address bindings.
+
+#### **I.6.8.2 Impacted components**
+
+This clause describes the component impacts for optional UE support of the Reg Event package.
+
+##### **I.6.8.2.1 UE**
+
+Support of "A SIP Event Package for Registrations" [IETF RFC 3680] is optional for the IPCablecom2 UE. If the UE does not support the registration-state event package described in [IETF RFC 3680], it does not perform procedures in [ITU-T J.366.4] related to subscription and notification of registration-state information.
+
+The primary implications of non-support for [IETF RFC 3680] are:
+
+- The UE does not receive explicit indication that additional AORs are implicitly registered, unless it supports the optional P-Associated-URI header (see clause I.6.12).
+- The UE may become unregistered without its knowledge. If this occurs, the UE will be unable to receive requests, and most non-REGISTER requests sent by the UE will either be dropped or rejected by the P-CSCF depending on whether a security association did or did not exist (see clause I.6.1).
+
+If the UE determines that it has been deregistered (e.g., a request is sent that times out or is rejected with an appropriate error code), the UE should attempt to recover using implementation specific procedures. As an example, the UE might perform network-initiated deregistration procedures as described in [ITU-T J.366.4].
+
+If the UE supports the registration-state event package, it should also support the P-Associated-URI header in order to determine if the public user identity used for registration is barred (see clause I.6.12.2.1).
+
+##### **I.6.8.2.2 P-CSCF**
+
+There is no impact to the P-CSCF. In IMS, it is already possible (e.g., as an abnormal case) that the P-CSCF receive requests from UE that have unknowingly become deregistered. Such requests may increase if the IPCablecom2 network performs network-initiated deregistration or re-authentication, and there are UEs which do not support the registration-state event package.
+
+### **I.6.9 Number portability**
+
+#### **I.6.9.1 Description**
+
+IPCablecom supports local number portability and equal access carrier routing. This clause describes how number portability and carrier routing data is obtained and used in an IPCablecom2 network.
+
+To support local number portability, the IPCablecom2 network should determine, when appropriate, whether or not the called number is ported. If the called number is ported to a PSTN destination, then the IPCablecom2 network should apply routing policy based on the LNP routing number, and also must pass the routing number and the LNP database dip indicator to the PSTN. The mechanism for obtaining the LNP data is out-of-scope and may vary based on the IPCablecom2 component that obtains the LNP data.
+
+Existing IMS procedures define that the S-CSCF resolves a Tel URI containing an E.164 address to a SIP URI using an ENUM/DNS mechanism. IPCablecom2 assumes that when such a Tel URI resolves to a SIP URI, an LNP Query is not required by the IPCablecom2 network. In this case, the request may be routed based on the SIP URI. As such, it is assumed that the ENUM/DNS Server containing the E.164 address to SIP URI mapping is synchronized with LNP porting procedures. The procedures/mechanisms for such synchronization are out of scope of this appendix.
+
+When a Tel URI containing an E.164 number cannot be resolved to a SIP URI, the IPCablecom2 network will obtain LNP data for the called number, where appropriate (for example, if the request is to be routed to an Inter-Exchange Carrier, the IPCablecom2 network is not required to perform the query. Rather, the "N – 1" carrier should typically perform the query).
+
+As a default, the LNP query, when required, is performed by the MGC, if an LNP query had not already occurred for the request (Note that since only "Local" porting is supported, it is reasonable that the request will be normally routed to an MGC that would be able to route appropriately based on the results of a query).
+
+The S-CSCF may also support LNP capabilities. If the S-CSCF supports LNP capabilities, the S-CSCF should be configurable to control whether or not these capabilities are to be utilized, to provide flexibility as to where the LNP query is performed. The mechanisms by which an S-CSCF obtains LNP data is out of scope of this appendix. (Mechanisms could include ENUM based mechanisms, including mechanisms by which LNP data is obtained from the E.164 to SIP URI resolution request.) Such mechanisms are the subject of currently evolving IETF Internet Drafts. Routing policies to handle the case where the S-CSCF resolves a Tel URI to a SIP URI, and also obtains LNP data associated with the Tel URI, are out of scope of this appendix.
+
+To support equal access carrier routing, the IPCablecom2 network selects the route to the PSTN based on the dialled or presubscribed carrier, and passes the carrier ID and the dial-around indicator to the PSTN. This implies that the Tel URI should support the "cic" and "dai" parameters, so the MGC can select the correct trunk group, and also pass the carrier id and dial-around-indicator to the PSTN.
+
+Note that current IPCablecom2 requirements do not call for support of a presubscribed carrier on a subscriber basis. Rather, a carrier may be presubscribed for all subscribers on a network basis. The BGCF may support addition of the network assigned carrier to the Tel URI via the "cic" parameter and also update the "dai" parameter. If supported, the BGCF adds these parameters based on routing
+
+policy/configuration. Note these parameters may have already been added by a prior network component, and hence should not be overwritten by the BGCF.
+
+The following responsibilities related to equal access are in the scope of an application server:
+
+- Setting/policing the dial around indicator for a carrier ID provided by a UE in a request.
+- Obtaining the carrier id for freephone calls.
+- Populating the carrier and dial around indicator for a presubscribed carrier, for the case where a presubscribed carrier has been configured for an individual subscriber.
+
+NOTE – As discussed previously, this is not a requirement currently, but should it be required, it could be supported in this fashion.
+
+IPCablecom2 supports the number portability and carrier routing requirements using the Tel URI LNP and carrier routing parameters and the dial-around-indicator parameter defined in [ITU-T J.178].
+
+#### **I.6.9.2 Impacted components**
+
+In order to support number portability and carrier routing, the number portability information must be carried in the SIP signalling. Specifically, the Tel URI needs to support the "rn", "cic", and the "npdi" parameters, and the "dai" parameter defined in [ITU-T J.178]. This information is used by the routing proxies (e.g., BGCF) to select the correct hop-off point to the PSTN, and by the PSTN gateway to communicate the correct routing information to the PSTN. These parameters can be carried in a native Tel URI, or the SIP equivalent of a Tel URI where user=phone.
+
+##### **I.6.9.2.1 UE**
+
+The only responsibility of the UE in support of carrier routing is to identify a user-dialled carrier to the network on an originating call. The UE does this by recognizing user-dialled carrier digits provisioned via a digit map, and identifying the carrier in the Tel URI "cic" parameter of the originating INVITE.
+
+Alternately, the digit map may specify that the UE must report all dialled digits, including the dialled carrier digits, in a SIP URI with user parameter of "user=dialstring". With this approach, an AS would be required to extract the CIC and normalize the Tel URI.
+
+Mechanisms to configure the digit map to control the UE behaviour are out of scope of this appendix.
+
+The UE does not play any other role in support of number portability.
+
+##### **I.6.9.2.2 S-CSCF**
+
+As specified in [ITU-T J.366.4], when the originating S-CSCF receives an originating request with a Request-URI of the Tel URI form, then it must attempt to resolve the E.164 address to a globally routable SIP URI using ENUM. If the resolution fails, then the S-CSCF assumes that the call is destined for the PSTN, and forwards the INVITE to the BGCF for further routing.
+
+IPCablecom2 enhances these requirements to support number portability. The S-CSCF may support number portability capabilities. If so, the S-CSCF should provide configuration controls that allow the operator to enable or disable the number-portability procedures. This will enable the operator to choose whether the LNP query is done by the S-CSCF, or by a downstream entity such as the MGC, or PSTN.
+
+If the S-CSCF has been configured to support number portability, then once it has determined that a call is destined for the PSTN, the originating S-CSCF must determine whether or not the called number is ported, and, if it is ported, then the actual routing number. How the S-CSCF gets this information is not specified (for example, it could be via an ENUM query). If the number is ported, then the originating S-CSCF must add an "rn" parameter to the request Tel URI to identify the
+
+routing number, and add an "npdi" parameter to indicate that the LNP database dip has been performed.
+
+If the S-CSCF is configured to not support number portability, then it will forward requests destined for the PSTN to the BGCF without populating the Tel URI number-portability parameters.
+
+Policies and procedures for handling scenarios where both a SIP URI, and Tel URI with number portability information, are obtained from an attempt to resolve an E.164 address to a SIP URI, (should this be possible with some mechanisms), are out of scope of this appendix.
+
+##### **I.6.9.2.3 BGCF**
+
+The BGCF receives INVITE requests from the S-CSCF and selects the best route to the PSTN based on locally configured routing policy. As specified in [ITU-T J.366.4], the input to the routing decision is the called telephone number identified in the Tel URI of the INVITE request URI. IPCablecom2 enhances the routing requirements to include the Tel URI "cic" and "rn" parameters, and as a result the BGCF may support use of these parameters in routing decision. How these parameters affect routing is not specified.
+
+The BGCF may support addition of the "cic" and "dai" parameters to the Tel URI, to support a network-wide presubscribed carrier. Addition of these parameters is based on routing policy. The attributes of the request being routed may determine whether a "cic" parameter is added. The BGCF shall allow for these parameters to have already been added to the request by another network component, and hence not overwrite the parameters if already provided.
+
+##### **I.6.9.2.4 MGC**
+
+The MGC receives requests from the BGCF for routing to the PSTN or from the PSTN for routing into the IPCablecom network.
+
+Requests from the BGCF may have a Tel URI that contains the carrier ("cic") and/or number portability ("npdi", "rn") parameters. Requests from the PSTN may also contain number portability parameters.
+
+The MGC will determine whether to make an LNP query based on local configuration, and the contents of the request, including the received number portability parameters.
+
+MGC routing policy includes routing based on carrier and number portability parameters. The details of MGC routing policy are outside the scope of this appendix.
+
+### **I.6.10 Globally routable user agent URI (GRUU)**
+
+#### **I.6.10.1 Description**
+
+The support of SIP globally routable user agent URI (GRUU) is optional for the UE in the IPCablecom2 SIP architecture. GRUU benefits IPCablecom2 by permitting certain call features, such as call transfer, to accurately target SIP requests to a particular SIP user agent instance of a UE. It also permits features to be defined to apply appropriately to requests that are intended for a particular SIP user agent instance of a UE rather than generally to a public user identity. For instance, when a request is targeted to a particular UE via a GRUU, it may be desirable to abstain from retargeting the request to voicemail.
+
+#### **I.6.10.2 Impacted components**
+
+This clause describes the component impacts for support of GRUU.
+
+##### **I.6.10.2.1 UE**
+
+An IPCablecom2 UE supporting GRUU will need to comply with the user agent requirements and guidelines under development.
+
+- The UE must request a GRUU when registering, and retrieve and retain the GRUU provided in the registration response.
+- If the registered public user identity is part of an implicit registration set, the UE must also obtain and retain the GRUU for each implicitly registered public user identity. (See clause I.6.10.3 for more information.)
+
+When sending SIP requests or responses that require a contact address, the UE should use a GRUU rather than the contact URI it registered.
+
+- In particular, the UE must use the corresponding retained GRUU as a contact address when sending SIP requests with a "From" header containing a registered public user identity.
+- The UE must also use the corresponding retained GRUU as a contact address when responding to SIP requests where the P-called-party is an implicitly registered public user identity.
+
+##### **I.6.10.2.2 S-CSCF**
+
+The S-CSCF needs to be capable of responding to registration requests that ask for GRUU URIs to be returned. In this case, it needs to construct and return a GRUU that is linked to the provided public user identity and instance ID.
+
+In addition to servicing requests addressed to public user identities it is responsible for, an S-CSCF must also service requests addressed to any GRUU that was previously assigned to a public user identity it is responsible for. This remains the case even when responsibility for a public user identity is transferred from one S-CSCF to another.
+
+To meet this need, by convention, the GRUU format for IPCablecom2 is defined as follows:
+
+- The GRUU associated with a public user identity in SIP or SIPS format is the same URI as the public user identity with the addition of a 'gruu' URI parameter and an 'opaque' parameter.
+- For a URI that contains a telephone number, a GRUU may be requested by using a SIP URI that includes a properly formatted telephone number in the user part of the SIP URI, together with the domain name of the provider and a 'user=phone' parameter. Indeed, a GRUU may not be requested for a public user identity in TEL URI because a URI following the tel format may not be registered. The resulting GRUU may be used for both the SIP and TEL forms of the public user identity.
+- The 'opaque' parameter of the GRUU returned by the S-CSCF consists of an "opaque=" parameter name followed by a value identical to the value of the 'sip.instance' parameter provided by the UE in the REGISTER request.
+
+When a request is addressed to a GRUU, the user profile must be able to differentiate which services are to be applied to the request based on the target of the request being a GRUU, or a public user identity. This may be achieved via a service point trigger (SPT) which tests the Request URI of the current request for the presence of a 'gruu' URI parameter.
+
+As described in the GRUU specification, when a SIP request is made to a URI with the GRUU property, the routing logic is dictated by the GRUU property. Therefore, the S-CSCF logic for translating the Request URI of a terminating request is different for a GRUU than a public user identity. For a GRUU, the only possible target is a contact registered with the public user identity and instance ID associated with the GRUU.
+
+#### **I.6.10.3 IPCablecom2 IMS Delta specification**
+
+The following IPCablecom2 IMS Delta specifications contain the necessary requirements for globally routable user agent URI (GRUU): ITU-T Recs J.366.2, J.366.3, [ITU-T J.366.4] and [ITU-T J.366.5].
+
+### **I.6.11 Registration state event package extension for GRUU**
+
+#### **I.6.11.1 Description**
+
+Additional extensions are defined to support the conveyance of GRUU URIs in the SIP registration event package. The registration-event package extension for GRUU must be supported if GRUU is supported by the IPCablecom2 elements (UE, S-CSCF and HSS). The support of registration-event package extension for GRUU is otherwise optional in the IPCablecom2 SIP signalling architecture.
+
+Reg-event package extension for GRUU support is optional in the IPCablecom2 SIP signalling architecture. It enhances the information provided by the reg event package to include a GRUU if one is assigned for a registered contact.
+
+This functionality is included in IPCablecom2 because it allows a UE to obtain all the GRUUs associated with an implicit registration set. Indeed, when a UE registers and requests the assignment of a GRUU, the response will contain the corresponding GRUU for the public user identity that was registered. However, if the public user identity is part of an implicit registration set, then registrations of the same contact are made to each of those public user identities. Each results in the assignment of a distinct GRUU, but there is no way to obtain those GRUUs in the response to the REGISTER. If the UE has a subscription to the registration event package, then the inclusion of the registration event package extension for GRUU means that the UE will receive the GRUUs associated with an implicit registration set in a notification.
+
+#### **I.6.11.2 Impacted components**
+
+This clause describes the component impacts for optional UE support of the Reg Event GRUU extension.
+
+##### **I.6.11.2.1 UE**
+
+If a UE has subscribed to the reg event package, and subsequently receives a notification indicating that an implicit registration has occurred for a contact the UE has registered, then the UE must retain the GRUU from the notification for future use. The manner in which this is used is covered by clause I.6.10.
+
+##### **I.6.11.2.2 S-CSCF**
+
+When sending notification for the reg event package, the S-CSCF must use the reg event package to include the GRUU for each registered Contact that has been assigned a GRUU.
+
+#### **I.6.11.3 IPCablecom2 IMS Delta specification**
+
+The following IPCablecom2 IMS Delta specification contains the necessary requirements for Registration state event package extension for GRUU: [ITU-T J.366.4].
+
+### **I.6.12 Private 3GPP headers**
+
+A set of private SIP headers for use by 3GPP is described in [IETF RFC 3455]. Of these, there are two p-headers whose requirements in IPCablecom2 differ from those of IMS.
+
+NOTE – P-headers described in [IETF RFC 3455] which are not identified in this clause are supported by IPCablecom2 without change.
+
+#### **I.6.12.1 Description**
+
+##### **I.6.12.1.1 P-Associated-URI header**
+
+The P-Associated-URI header is received by the UE in the 200 (OK) response to a REGISTER request. According to [ITU-T J.366.4], it contains the registered public user identity and its associated set of implicitly registered public user identities.
+
+NOTE – This differs from the description in [IETF RFC 3455].
+
+According to IMS registration procedures, the UE is required to support this header, which indicates to the UE the following information:
+
+- The set of implicitly registered public user identities.
+- The default public user identity, which will be asserted by the P-CSCF in the P-Asserted-Identity procedures if the UE does not include a P-Preferred-Identity header, or does not include a registered public user identity in the P-Preferred-Identity header.
+- Whether or not the public user identity used for registration is barred, since barred identities are not included in the P-Associated-URI header.
+
+In IPCablecom2, support for the P-Associated-URI header is optional for the UE.
+
+##### **I.6.12.1.2 P-Access-Network-Info header**
+
+According to IMS, the P-Access-Network-Info header must be included by the UE in any SIP message (with some exceptions) sent integrity protected. It identifies the access technology being used for IP-connectivity (i.e., IP-CAN), and is passed by the S-CSCF to trusted application servers as part of 3rd party registration.
+
+Its potential usages include:
+
+- emergency services, as described in clause 5.2.10 of [ITU-T J.366.4];
+- determination of whether SIP compression is needed between the UE and P-CSCF, as described in clause I.6.3;
+- optimization of the values of SIP timers, as described in clause I.6.14; and
+- optimization of services based on access network type.
+
+In IPCablecom2, the P-Access-Network-Info header is included by the UE only if the access technology is known.
+
+NOTE – New access-type value(s) for IPCablecom2 must be registered with the appropriate standards body.
+
+#### **I.6.12.2 Impacted components**
+
+This clause describes the component impacts for optional support of the P-Associated-URI and P-Access-Network-Info headers.
+
+##### **I.6.12.2.1 UE**
+
+If the P-Associated-URI header is not supported by the UE, the UE has no ways of knowing whether or not the user identity it used during registration is barred. Therefore, care must be taken that UEs not supporting the P-Associated-URI header do not register using a barred identity. Barred identities are not bound to the contact information, and cannot be used for identity assertion. The primary implications of non-support for the P-Associated-URI header are:
+
+- The UE does not receive explicit indication that additional AORs are implicitly registered unless it supports the optional registration-state event package (see clause I.6.8).
+- If the public user identity used for registration is barred, the UE will not be able to successfully subscribe to the registration-state event package, if there is no security association.
+
+- If a request is issued with a P-Preferred-Identity containing a barred public user identity, the P-CSCF will ignore it and insert a P-Asserted-Identity with a known default public user identity instead.
+
+The UE shall support the P-Access-Network-Info header procedures described in [ITU-T J.366.4], with the following clarification:
+
+- The P-Access-Network-Info header is inserted by the UE, only if the access network technology is known.
+
+##### **I.6.12.2.2 P-CSCF**
+
+If the P-CSCF receives a REGISTER request that does not contain a P-Access-Network-Info header and the P-CSCF has knowledge of the access technology being used at the UE, the P-CSCF shall insert the P-Access-Network-Info header.
+
+NOTE – Since the P-Access-Network-Info header may not be inserted by either the UE or P-CSCF (i.e., when neither have knowledge of the access technology), features and services that make use of the P-Access-Network-Info must appropriately handle its absence.
+
+##### **I.6.12.2.3 S-CSCF**
+
+If the P-Associated-URI header is not supported by the UE and signalling security is disabled or optional, the originating S-CSCF may receive non-REGISTER requests that contain a barred public user identity in the P-Preferred-Identity and/or From header. In this case, the S-CSCF shall reject the request by generating a 403 (Forbidden) response.
+
+### **I.6.13 Routing SUBSCRIBEs for configuration information**
+
+#### **I.6.13.1 Description**
+
+IPCablecom2 UEs obtain configuration information using the SIP protocol by subscribing to the ua-profile event package. The initial subscription for configuration is addressed to a special Request-URI that is device specific. The Request-URI is constructed by the UE from a UE-specific device identifier, combined with the domain name of the provider. The initial subscription request for configuration must be routed to an IPCablecom2 PAC element that is capable of providing a suitable device profile for the UE.
+
+It is important to differentiate between two classes of UEs for which the SUBSCRIBE requests for configuration information must be processed:
+
+- 1) UEs whose device URI is known to the system.
+- 2) UEs whose device URI is unknown to the system.
+
+The procedures described below allow the SUBSCRIBE requests for configuration information to be properly routed in either case.
+
+A UE may or may not be aware whether its device URI is known or unknown by the network. If it is unknown then it will not be able to register. The procedure it follows will work in either case. It sends a subscribe request for its profile before registering. This request is addressed to the device-specific URI. It includes a From header containing the device-specific URI, and should include a P-Preferred-Identity header also containing the device-specific URI. This follows the procedures of clause I.6.1.2.1 that apply when there is no security association between the UE and the P-CSCF and the UE has not registered.
+
+Because the UE has not registered, the P-CSCF has no basis for authenticating the request. Instead, it leaves the P-Preferred-Identity header in place, deferring authentication to a subsequent server. It uses the P-Preferred-Identity header if present, or absent that of the From header, to select an I-CSCF for subsequent processing, and forwards the request there.
+
+In the absence of a P-Asserted-Identity header, the I-CSCF uses the P-Preferred-Identity if present, or the From header if the P-Preferred-Identity header is also absent, to determine the target for routing the request for origination processing.
+
+If the device URI is known, there will be an explicit entry for it in the HSS, as a public user identity. The I-CSCF then routes the request to the S-CSCF serving this public user identity.
+
+The device URI for an unknown device is by definition unknown to the HSS, so no exact matching entry is present in the HSS. However, when support for unknown devices is desired, a wildcard PSI entry shall be present in the HSS that matches all desired unknown device URIs. For example, the following two values may be sufficient:
+
+sip:MAC%3a!.\*!@provider.net
+
+sip:urn%3aauuid%3a!.\*!@provider.net
+
+The HSS entry should identify a PAC element that handles unknown subscriptions from unknown devices. Subscriptions by unknown devices are thus routed by the I-CSCF to this server for "orig" processing.
+
+The PAC element is responsible for any authentication or authorization it chooses to make for unknown devices. The server then chooses to honour the request or to refuse it. It was invoked to perform origination processing, so the request might need to be routed elsewhere for termination processing. However, for IPCablecom2, the only applicable case is where the origination and termination addresses are the same. So the server may simply honour the request without further routing. It utilizes information in the subscription request (e.g., device type information) to select a suitable default configuration for the device – one that will allow the device to utilize whatever restricted capabilities the provider may choose to permit. Typically, this is only for the purpose of initial communication sufficient to establish a business relationship between the provider and the user of the device, after which the device will change status, becoming *known* to the system. For further information, see [ITU-T J.364].
+
+#### **I.6.13.2 Impacted components**
+
+This clause describes the component impacts to support subscription to the UA profile event package before registration.
+
+##### **I.6.13.2.1 UE**
+
+A UE should subscribe for the device profile, using the device-specific URI, without first registering using that URI. It shall do so following the procedures of clause I.6.1.2.1 on Signalling Security and the UE.
+
+##### **I.6.13.2.2 P-CSCF**
+
+See clause I.6.1.2.2 on Signalling Security and the P-CSCF.
+
+##### **I.6.13.2.3 I-CSCF**
+
+See clause I.6.1.2.3 on Signalling Security and the I-CSCF.
+
+##### **I.6.13.2.4 S-CSCF**
+
+See clause I.6.1.2.4 on Signalling Security and the S-CSCF.
+
+##### **I.6.13.2.5 HSS**
+
+The HSS must handle the case where a Request-URI matches two entries in the HSS – one for a wildcarded PSI and one for a public user identity. In this case, the entry for the public user identity shall take precedence over that for the wildcarded PSI.
+
+##### **I.6.13.2.6 PAC element**
+
+The PAC element for a known device URI shall operate as a terminating application server on behalf of the corresponding user. It may detect that the device is known by the presence of a P-Asserted-Identity header naming containing the device URI.
+
+The PAC element for an unknown device URI shall function as an originating PSI server. It may detect that the device is unknown by the absence of a P-Asserted-Identity header.
+
+#### **I.6.13.3 IPCablecom2 IMS Delta specification**
+
+The following IPCablecom2 IMS Delta specification contains the necessary requirements for Routing SUBSCRIBEs for configuration information: [ITU-T J.366.4].
+
+### **I.6.14 SIP timers**
+
+#### **I.6.14.1 Description**
+
+To accommodate 3GPP air interface processing and transmission delays, 3GPP IMS Release 6 [ITU-T J.366.4] specifies a modified set of SIP timer values (compared with those defined in [IETF RFC 3261]) to be applied by the P-CSCF towards the UE and the UE towards the P-CSCF. For broadband access, this consideration does not apply and standard [IETF RFC 3261] SIP timer values would apply. As part of the 3GPP IMS Release 7 support for "Fixed Broadband", UEs using broadband access technology, and a P-CSCF that interacts with such a UE, use the standard [IETF RFC 3261] SIP timer values.
+
+IP Cablecom2 incorporates these 3GPP IMS Release 7 changes for SIP timers.
+
+This solution is dependent on specification of a new access type for the P-Access-Network-Info header, representing IPCablecom2 broadband access network technology. Refer to clause I.6.12.1.2 for further details.
+
+Since the UE and P-CSCF need to use a consistent set of SIP timer values, if the UE does not provide a P-Access-Network-Info header, both the UE and P-CSCF use the standard [IETF RFC 3261] SIP timer values. Note that this is an incremental requirement over the existing 3GPP Release 7 changes.
+
+Note that the 3GPP IMS Release 7 solution may be subject to further study within 3GPP to determine if there are better ways to determine access delays and whether SIP timer values should be modified. As such, IPCablecom2 may realign with any future changes made in this area.
+
+#### **I.6.14.2 Impacted components**
+
+The required changes are identified and incorporated into Release 7.
+
+An incremental requirement is that since the UE and P-CSCF need to use a consistent set of SIP timer values, if the UE does not provide a P-Access-Network-Info header, both the UE and P-CSCF use the standard [IETF RFC 3261] SIP timer values.
+
+##### **I.6.14.2.1 UE**
+
+Only UEs using 3GPP wireless access technology uses the 3GPP-modified SIP timer values. Other UEs use standard [IETF RFC 3261] SIP timer values.
+
+##### **I.6.14.2.2 P-CSCF**
+
+The P-CSCF applies 3GPP-modified SIP timer values towards UEs on 3GPP wireless access technologies. For UEs on other access technologies, the P-CSCF applies standard [IETF RFC 3261] SIP timer values. The P-CSCF makes the determination based on the access type in P-Access-Network-Info. When no P-Access-Network-Info is provided by the UE, standard [IETF RFC 3261] timer values apply.
+
+#### **I.6.14.3 IPCablecom2 IMS Delta specification**
+
+The following IPCablecom2 IMS Delta specification contains the necessary requirements for SIP timers: See clause 7.7 of [ITU-T J.366.4].
+
+### **I.6.15 General changes**
+
+#### **I.6.15.1 Description**
+
+This clause describes a number of miscellaneous changes to IMS relevant to meet the IPCablecom2 requirements, including terminology clarifications, and the support of both IPv4 and IPv6 addressing.
+
+- [ITU-T J.366.4] uses terminology that implies access specific technology in some cases. The terms "mobile-originating", "mobile-originated", "mobile-terminating", "mobile-terminated" and "mobile-initiated" are used throughout TS 24.229. As part of the 3GPP IMS Release 7 support for "Fixed Broadband", the 3GPP specification, [ITU-T J.366.4] has been modified to correct the terminology, using the terms "UE-originating", "UE-originated", "UE-terminating", "UE-terminated" and "UE-initiated". IPCablecom2 implicitly assumes this change in terminology.
+- [ITU-T J.366.4] specifies procedures for derivation of public identity, private identity, and home network domain name when the UE contains a UICC but no ISIM. (Refer to clauses 4.2, 5.1.1.1A and Annex C of [ITU-T J.366.4]). Some UEs utilized in IPCablecom2 may have neither an UICC nor an ISIM. In such cases, the UE will be configured or provisioned with the required information. For more information regarding this case, please refer to Appendix III.
+
+The following should be recognized:
+
+- Some procedures in [ITU-T J.366.4] are explicitly described as pertaining to 3GPP Access. Such procedures are not applicable to broadband clients (Example: Clause 5.2.8.1 of [ITU-T J.366.4] "P-CSCF-Initiated call release" contains scenarios related to "radio coverage" and "radio interface resources").
+- [ITU-T J.366.4] also contains annexes that are explicitly targeted at GPRS access. Such annexes are self-evidently not applicable to IPCablecom2 broadband access, and corresponding material for IPCablecom2 may be contained in other IPCablecom2 specifications.
+
+#### **I.6.15.2 Impacted components**
+
+Changes required for generalization of access terminology (from "mobile-" to "UE") have been identified. These changes generalize [ITU-T J.366.4] but do not impact procedures. As such, no detailed breakdown of component impact is provided in this clause.
+
+#### **I.6.15.3 IPCablecom2 IMS Delta specification**
+
+The changes required for generalization of access terminology (from "mobile-" to "UE") are implicitly assumed and [ITU-T J.366.4] is not updated with these changes for simplicity.
+
+### **I.6.16 Interworking with previous IPCablecom releases**
+
+A UE must be able to establish voice sessions with endpoints supported in previous IPCablecom releases. For example, UEs and E-MTAs in the same operator's network must be able to call each other without having the calls routed through another IP carrier, or through the PSTN. Also, UEs must be able to establish calls to TGCP-based MG endpoints in order to interwork with the PSTN.
+
+Service control for UEs is not integrated in any way with service control for E-MTAs. UE service control is shared between the UE and its serving S-CSCF and associated application servers. E-MTA services are provided and controlled via NCS by the CMS. UEs and E-MTAs simply view each other as separate callable entities in the network.
+
+The ability to establish calls between UEs and other endpoints supported in previous IPCablecom releases is enabled by the SIP-based pkt-sig-2 interface that connects the S-CSCF, I-CSCF, and BGCF to the CMS and MGC (see Figure I.3). The requirements to support this interface on the CMS and MGC are defined in [ITU-T J.178].
+
+# Appendix II
+
+# Quality of service architecture technical overview
+
+(This appendix does not form an integral part of this Recommendation)
+
+## II.1 Introduction
+
+This appendix provides an overview of the IPCablecom2 quality of service (QoS) architecture. Specifically, it describes the way in which IPCablecom multimedia is used to provide QoS applications built on top of IPCablecom. To aid the reader in understanding the IPCablecom2 QoS architecture, the high level goals and specific logical components and interfaces defined are discussed in this appendix.
+
+### II.1.1 IPCablecom multimedia overview
+
+IPCablecom multimedia defines an IP-based platform for delivering QoS-enhanced multimedia services over DOCSIS 1.1 (ITU-T Rec. J.112) or greater (for the remainder of this appendix, references to DOCSIS assume DOCSIS 1.1 or greater) access networks. This platform expands on the core capabilities of IPCablecom (e.g., QoS authorization and admission control, event messages for billing and other back-office functions, and security) to support a wide range of IP-based services beyond telephony. That is, while the IPCablecom architecture is customized for the delivery of residential telephony services, the IPCablecom multimedia architecture offers a general-purpose platform for cable operators to deliver a variety of IP-based multimedia services that require QoS treatment. For this reason, specific services are not defined or addressed.
+
+Although the IPCablecom multimedia platform is based upon IPCablecom work, the full voice infrastructure defined in IPCablecom is not a prerequisite to the deployment of multimedia services. Rather, it is intended that a particular cable operator may choose to initially deploy either voice or multimedia services, with the assurance that these platforms will seamlessly integrate and interoperate if and when they are deployed in parallel.
+
+## II.2 References
+
+This appendix uses the following additional informative references:
+
+- [ITU-T J.163] ITU-T Recommendation J.163 (2005), *Dynamic quality of service for the provision of real-time services over cable television networks using cable modems*.
+- [ITU-T J.179 App.I] ITU-T Recommendation J.179 (2005), *IPCablecom support for multimedia. Appendix I: Background information*.
+- [ITU-T J.179] ITU-T Recommendation J.179 (2005), *IPCablecom support for multimedia*.
+- [ITU-T J.362] ITU-T Recommendation J.362 (2006), *IPCablecom2 control point discovery*.
+- [ITU-T J.365] ITU-T Recommendation J.365 (2006), *IPCablecom2 application manager interface*.
+- [ITU-T J.366.4] ITU-T Recommendation J.366.4 (2006), *IPCablecom2 IP Multimedia Subsystem (IMS): Session Initiation Protocol (SIP) and Session Description Protocol (SDP) – Stage 3 Specification*. (3GPP TS 24.229)
+- [IETF RFC 3264] IETF RFC 3264 (2002), *An Offer/Answer Model with the Session Description Protocol (SDP)*.
+- [IETF RFC 3890] IETF RFC 3890 (2004), *A Transport Independent Bandwidth Modifier for the Session Description Protocol (SDP)*.
+
+## **II.3 Terms and definitions**
+
+This appendix uses the following additional term:
+
+**II.3.1 IMS Release 6:** 3GPP IP multimedia subsystem suite of specifications – Approved version Release 6.
+
+## **II.4 Abbreviations and acronyms**
+
+This appendix uses the following additional abbreviations:
+
+|        |                                    |
+|--------|------------------------------------|
+| DQoS   | Dynamic Quality of Service         |
+| DSCP   | Differentiated Services Code Point |
+| P-CSCF | Proxy CSCF                         |
+| WS     | Web Services                       |
+
+## **II.5 QoS requirements and scope**
+
+The objective of this appendix is to provide an architecture definition for a UE device to obtain access to IPCablecom network resources. In particular, it describes a comprehensive mechanism for an IPCablecom network to request specific QoS resources required to support the media associated with SIP sessions over a DOCSIS network.
+
+This architecture also recognizes that IPCablecom will provide QoS for a wide variety of applications and services (voice, video, etc.); as such, it provides a generic mechanism to request access network resources and does not require applications to be aware of access network topology.
+
+### **II.5.1 Requirements**
+
+The following is a list of requirements that are considered essential for developing a general-purpose QoS architecture to satisfy the services envisioned for IPCablecom2:
+
+- The QoS architecture must service flow creation for UEs that are not QoS aware through a network-initiated policy push.
+- Define an IPCablecom2 application manager (IPAM), which will mediate QoS interaction between the P-CSCF and the Multimedia infrastructure.
+- Support packet marking and classification from the access network such that a QoS mechanism (e.g., Differentiated Services) can be used in the backbone network.
+- The IPAM must receive sufficient information from the P-CSCF regarding each flow which makes up a session such that it can:
+  - Construct an appropriate classifier while accommodating NAT traversal mechanisms.
+  - Construct a flow spec or alternative traffic profile which reflects the Least Upper Bound of the resource requirements of any alternative codec which may be permitted for the flow including bandwidth, packetization rate, and scheduling type.
+  - Determine the type of media so that it can select an appropriate differentiated services code point (DSCP).
+- The IPAM must receive sufficient information from the P-CSCF for each session such that it can:
+  - Construct a suitable correlation identifier for accounting records.
+  - Identify the subscriber for the purposes of accessing subscriber profile data.
+  - Recognize if the session must be given higher priority (e.g., an emergency call).
+- The interface must allow reservation and commitment of resources to occur in separate steps.
+
+### II.5.2 Scope
+
+The current scope of the IPCablecom QoS architecture is limited to the DOCSIS-based access portion of a cable operator's network and on how the IPCablecom network can request QoS resources from the IPCablecom Multimedia framework. Therefore, the architecture described in this appendix does not address the case of a roaming UE that may attach to the IPCablecom network from non DOCSIS-based access networks.
+
+Further, this architecture does not prohibit the use of the QoS capabilities in IPCable2Home enabled networks. However, providing QoS in IPCable2Home network is not within the scope of this appendix.
+
+## II.6 QoS architecture framework
+
+Within the overall goal to leverage existing industry standards whenever possible, a specific objective is to align with the IMS architecture and specifications being developed by 3GPP. Specifically, IPCablecom2 will align with IMS Release 6 and reuse many of the basic IMS components and reference points. Another equally important objective is to make use of the rich set of QoS capabilities provided by IPCablecom multimedia.
+
+IPCablecom2 must support a policy push model in order to interface with IPCablecom multimedia. Release 6 of the IMS provides two related mechanisms for providing the Quality of Service and charging for the IP service flows that make up multimedia sessions. Service-based local policy (SBLP) provides a mechanism for the authorization, establishment and modification of IP bearers using an authorization token similar to the IPCablecom Dynamic Quality of Service Architecture [ITU-T J.163]. As in DQoS, the establishment of PDP contexts using SBLP requires active involvement of a QoS aware user equipment.
+
+The second mechanism is flow-based charging (FBC). FBC provides a means to identify, police and charge for the IP flows that make up a session using a network-initiated push mechanism similar to IPCablecom multimedia. However, FBC does not provide a mechanism for the establishment of new bearers (or service flows). Neither SBLP nor FBC as defined in IMS Release 6 provides the complete information necessary to support the establishment of service flows using IPCablecom multimedia. Future alignment with the policy and charging control work being undertaken in IMS Release 7 is possible.
+
+### II.6.1 QoS architecture reference model
+
+The IPCablecom2 QoS architecture is illustrated in Figure II.1. The QoS infrastructure defined in IMS Release 6 is not sufficiently access agnostic to satisfy the requirements of IPCablecom2. Therefore, IPCablecom2 uses the IPCablecom multimedia components including the policy server, CMTS, and cable modem. The IPCablecom2 application manager is a specialized application manager which receives session level QoS requests via SOAP from the P-CSCF and creates and manages the IPCablecom multimedia gates for each flow in the session using the IPCablecom multimedia pkt-mm-3 interface.
+
+The QoS architecture does not prohibit the use of the IMS defined Gq reference point for those UEs that may access services over a GPRS network. Figure II.1 illustrates the coexistence of the IMS defined QoS architecture for GPRS based devices with the IPCablecom2 multimedia QoS architecture used for UEs accessing services via a DOCSIS network.
+
+![Figure II.1 – QoS signalling reference points. A block diagram showing network elements and their interconnections. On the left, a cloud labeled 'GPRS network' is connected to a 'UE' (User Equipment) box. The 'UE' is connected to a 'P-CSCF' box via a vertical line labeled 'Gm'. The 'P-CSCF' is connected to a 'PDF' box via a horizontal line labeled 'Gq'. The 'P-CSCF' is also connected to an 'IP Cablecom application manager' box via a horizontal line labeled 'pkt-qos-1'. The 'IP Cablecom application manager' is connected to a 'Policy server' box via a horizontal line labeled 'pkt-mm-3'. The 'Policy server' is connected to a 'CMTS' box via a vertical line labeled 'pkt-mm-2'. The 'CMTS' is connected to a 'CM' (Cable Modem) box via a vertical line labeled 'pkt-mm-1'. A horizontal line also connects the 'UE' to the 'CM'. A label 'J.360_FIL1' is at the bottom right of the diagram.](8c3eb53c927f55acd19723cfcd0c43b6_img.jpg)
+
+Figure II.1 – QoS signalling reference points. A block diagram showing network elements and their interconnections. On the left, a cloud labeled 'GPRS network' is connected to a 'UE' (User Equipment) box. The 'UE' is connected to a 'P-CSCF' box via a vertical line labeled 'Gm'. The 'P-CSCF' is connected to a 'PDF' box via a horizontal line labeled 'Gq'. The 'P-CSCF' is also connected to an 'IP Cablecom application manager' box via a horizontal line labeled 'pkt-qos-1'. The 'IP Cablecom application manager' is connected to a 'Policy server' box via a horizontal line labeled 'pkt-mm-3'. The 'Policy server' is connected to a 'CMTS' box via a vertical line labeled 'pkt-mm-2'. The 'CMTS' is connected to a 'CM' (Cable Modem) box via a vertical line labeled 'pkt-mm-1'. A horizontal line also connects the 'UE' to the 'CM'. A label 'J.360\_FIL1' is at the bottom right of the diagram.
+
+**Figure II.1 – QoS signalling reference points**
+
+Reference points pkt-mm-1 through pkt-mm-3 are defined by IPCablecom multimedia. IPCablecom2 introduces new QoS reference points pkt-qos-1 and pkt-qos-2. Table II.1 describes these interfaces briefly while Table II.2 provides a brief description of each network element.
+
+**Table II.1 – QoS reference points**
+
+| Reference point | IP Cablecom network elements | Reference point description                                                                                                                                                                                                                                                                                                                                     |
+|-----------------|------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| pkt-mm-1        | CMTS – CM                    | The CMTS uses DOCSIS defined DSX signalling to instruct the CM to set up, tear down, or change a DOCSIS service flow in order to satisfy a QoS request.                                                                                                                                                                                                         |
+| pkt-mm-2        | Policy server – CMTS         | The interface supports proxy QoS requests on behalf of a UE. This interface is fundamental to the policy-management framework. It controls policy decisions, which are pushed by the policy server (PS) onto the CMTS and is defined by [ITU-T J.179]. In some scenarios, this interface is also used to inform the PS when QoS resources have become inactive. |
+| pkt-mm-3        | IPAM-PS                      | This interface allows the IPCablecom application manager (IPAM), a specialized application manager defined in IPCablecom, to request that the PS install a policy decision on the CMTS on behalf of the UE and is defined by [ITU-T J.179]. This interface may also be used to inform the IPAM of changes in the status of QoS resources.                       |
+| Gm              | UE – P-CSCF                  | Allows the UE to communicate with the P-CSCF for registration and session control. This reference point is SIP-based and is described in [ITU-T J.366.4].                                                                                                                                                                                                       |
+| Mw              | CSCF – CSCF                  | Allows the communication and forwarding of signalling messaging among CSCFs in support of registration and session control. This reference point is SIP-based.                                                                                                                                                                                                  |
+
+**Table II.1 – QoS reference points**
+
+| Reference point | IPCablecom network elements | Reference point description                                                                                                                                                                                                                 |
+|-----------------|-----------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Gq              | P-CSCF – PDF                | The Gq interface is used for session based policy set-up information exchange between the policy decision function (PDF) and the P-CSCF.                                                                                                    |
+| pkt-qos-1       | P-CSCF – IPAM               | This SOAP/XML based interface between the P-CSCF and IPCablecom application manager conveys session level QoS information. The IPAM uses this information to form suitable messages for pkt-mm-3 interface and is defined by [ITU-T J.365]. |
+| pkt-qos-2       | Policy server – CMTS        | The policy server uses the control point discovery protocol to determine the serving CMTS in the network for a given UE. This reference point is based on IPCablecom specification [ITU-T J.362].                                           |
+
+**Table II.2 – QoS network elements**
+
+| IPCablecom network element            | Brief description                                                                                                                                                                                                                                                                                        |
+|---------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| UE                                    | A UE is a client and interacts with the network to access services and provides interfaces to users or entities.                                                                                                                                                                                         |
+| P-CSCF                                | The P-CSCF parses the SDP in SIP messages and implements the web service client interface to provide QoS by interacting with the application manager. It reserves, commits, and removes QoS on access network.                                                                                           |
+| IPCablecom application manager (IPAM) | The IPCablecom application manager is responsible for managing QoS resources in the access network as requested by the P-CSCF. The IPCablecom application manager receives session level QoS messages from the P-CSCF, and formulates and sends IPCablecom multimedia QoS messages to the policy server. |
+| Policy server (PS)                    | The policy server acts as an intermediary between application manager(s) and CMTS(s). It applies network policies to application manager messages and proxies then to the CMTS.                                                                                                                          |
+| Cable modem termination system (CMTS) | The CMTS is a device at a cable headend which implements the DOCSIS RFI MAC protocol and connects to CMs over an HFC network.                                                                                                                                                                            |
+| Cable modem (CM)                      | DOCSIS compliant cable modem.                                                                                                                                                                                                                                                                            |
+
+### II.6.2 Relationship with 3GPP IMS Release 6
+
+The IPCablecom<sup>2</sup> Recommendations include an enhanced version of 3GPP IMS Release 6 TS 24.229 to document the QoS requirements for the call control protocol using SIP and SDP. A summary of the modifications to TS 24.229 follows:
+
+- Added requirement to include the "b=" media descriptor and the "TIAS" bandwidth modifier defined in [IETF RFC 3890] to describe the bandwidth required for the session.
+- Additional SDP types are added to the SDP profile definition for user agents. The SDP types include:
+  - Packet time (a=ptime) – The type must be included by UEs to indicate the packetization time which the UE expects to receive traffic.
+
+- Maximum packet rate (a=maxprate) – This type must be included when the UE is using a non-well known IPCablecom codec.
+- NAT (a=Local-Turn) – This type must be included by the UE when it is using a TURN server to transverse a local NAT device.
+
+### II.6.3 Relationship with multimedia pkt-mm-11
+
+The IPCablecom multimedia architecture also defines a web services based interface to the application manager from an upstream application server. This interface is labeled pkt-mm-11 in the multimedia technical report [ITU-T J.179 App.I]. While this interface could be used by the P-CSCF to interface with the IPCablecom2 application manager, a new interface was developed to allow for more efficient P-CSCF operation. The multimedia defined interface would require a double translation of the session parameters resulting in extra overhead on the P-CSCF to translate the session parameters into a generic QoS request. The IPCablecom-defined interface allows the P-CSCF to simply pass the session parameters in whole to the IPCablecom AM, which is then responsible for the translation to a valid IPCablecom multimedia QoS message. This approach reduces the amount of translations required and allows the P-CSCF to maintain a more access network agnostic implementation.
+
+## II.7 Architecture description
+
+Clause II.6 described a set of logical network entities grouped by specific service functions (QoS), as well as a set of reference points that support the information flows exchanged between the functional groups and network entities. This clause provides a more detailed discussion of those logical elements and the associated reference points which are new to the IPCablecom architecture. It also provides an overview of other topics related to the QoS architecture that are not documented elsewhere.
+
+### II.7.1 Functional components
+
+In this clause, additional detail is provided on the IPCablecom2 application manager and P-CSCF and their role as related to the QoS architecture.
+
+#### II.7.1.1 P-CSCF
+
+In addition to its role in providing the UE connectivity to the IPCablecom network, the P-CSCF is also responsible for reserving, committing and releasing QoS resources for a given session. It is important to note that the P-CSCF does not actually determine the QoS resources necessary for the session, rather it simply proxies the session description information to the IPCablecom2 application manager and indicates whether to reserve or commit the resources for the session. While the architecture supports a two-phase commit operation (reserve followed by a commit), there are no requirements on the P-CSCF to follow this approach. A single-phase commit (reserve and commit resources in a single request) may be used.
+
+Once the session has ended, the P-CSCF releases the resources allocated to the session.
+
+#### II.7.1.2 IPCablecom2 application manager (IPAM)
+
+The IPCablecom2 application manager is primarily responsible for determining the QoS resources needed for the session based on the received session descriptors and managing the QoS resources allocated for a session.
+
+Determining the QoS resources for a session involves interpreting the session descriptor and calculating how much bandwidth is required, determining the traffic scheduling type, and populating the traffic classifiers. This also involves determining the number of flows necessary for the session (voice only vs voice and video session) and managing the association of the flows to the session.
+
+#### II.7.1.3 Relationship between P-CSCF and IPAM
+
+The IPCablecom multimedia architecture provides a well understood relationship between the IPAM and PS. The relationship between the P-CSCF and IPAM is described here. The QoS architecture was not developed with any pre-conceived relationship between the two network elements. While the choice of how to deploy P-CSCFs and IPAMs and their associated cardinality is mainly a deployment decision, Figures II.2 and II.3 represent what are believed to be the most popular deployment scenarios.
+
+![Diagram of a one-to-one relationship between P-CSCF and IPCablecom application manager.](66e89867f97592fd4bfab0e4f2b2054f_img.jpg)
+
+A diagram showing a one-to-one relationship. On the left is a rectangular box labeled "P-CSCF". On the right is a rectangular box labeled "IPCablecom application manager". A single horizontal line connects the two boxes. Below the right box is the text "J.360\_FII.2".
+
+Diagram of a one-to-one relationship between P-CSCF and IPCablecom application manager.
+
+**Figure II.2 – One to one**
+
+![Diagram of a many-to-one relationship between P-CSCF and IPCablecom application manager.](1ea7909aea2fb749a6fe98fbdb8cacae_img.jpg)
+
+A diagram showing a many-to-one relationship. On the left, there are two rectangular boxes, each labeled "P-CSCF", stacked vertically. On the right is a rectangular box labeled "IPCablecom application manager". Two lines originate from the right side of the two "P-CSCF" boxes and converge on the left side of the "IPCablecom application manager" box. Below the right box is the text "J.360\_FII.3".
+
+Diagram of a many-to-one relationship between P-CSCF and IPCablecom application manager.
+
+**Figure II.3 – Many to one**
+
+Figure II.2 illustrates a one-to-one relationship between the P-CSCF and the IPAM. Such a deployment scenario, while extremely simple to manage, may not be the most efficient use of resources. Figure II.3 illustrates a many-to-one relationship between the P-CSCF and the IPAM. This scenario maintains the simplicity of a one-to-one relationship (since the P-CSCF does not have to determine which IPAM to send its request to), but may more efficiently utilize IPAM resources.
+
+Another possible scenario not shown is a one-to-many relationship (or many to many). In this case the P-CSCF may communicate with multiple IPAMs. While such a scenario is supported, no guidance is provided on how the P-CSCF determines which IPAM to send its requests to. Such a scenario may become necessary as the network evolves and different application managers are invoked for different access networks or in certain roaming cases.
+
+### II.7.2 Protocol interfaces and reference points
+
+This appendix has identified several interfaces, or reference points, in the IPCablecom2 QoS architecture. The majority of these reference points are existing interfaces defined by IPCablecom multimedia. An overview of the P-CSCF to IPAM protocol interface is provided within this clause as it is the only interface defined by IPCablecom.
+
+It is possible that this interface may not exist in a given vendor's product implementation. For example, if a P-CSCF vendor chooses to integrate the IPAM within the P-CSCF, the P-CSCF to IPAM interface would be internal to that product.
+
+#### **II.7.2.1 P-CSCF – IPAM interface description**
+
+The P-CSCF to IPAM interface is based on web services. It allows the P-CSCF to request and delete Quality of Service resources within an IPCablecom multimedia enabled DOCSIS network.
+
+The IPCablecom2 application manager web services interface enables a P-CSCF to request QoS handling in the access network based on the session description protocol (SDP) parameters contained in the offer and answer as defined in [IETF RFC 3264]. The IPAM uses the IPCablecom multimedia pkt-mm-3 interface to communicate these requirements to an IPCablecom multimedia policy server.
+
+### **II.7.3 Application of QoS policy within IPCablecom**
+
+The term policy control has often been used to describe the process by which a new dynamic service flow or bearer is created in the access network at the request of an application. This makes sense since establishing a new service flow in the access network involves the installation of a new dynamic policy in the policy enforcement point. This dynamic policy determines the treatment of the packets which make up the new service flow within the access network throughout the duration of the session.
+
+The focus of this clause is higher levels of policy which may affect the disposition of a user request as it is processed within the network. Such policies could be implemented at several levels in the network in order to further the business needs of the network operators. Levels where policy can be applied include:
+
+- Application level: Applications may employ policy to constrain use of an application based on subscription or other information.
+- Signalling network level: For example, network or subscription based restrictions on the use of certain media parameters in an SDP offer may be enforced in an IPCablecom network by the P-CSCF or S-CSCF respectively by sending a negative response to the SIP message as described in clauses 6.2 and 6.3 of [ITU-T J.366.4].
+- Bearer network level: Each of the network elements in the bearer network (IPCablecom application manager, policy server and CMTS) serve unique roles as they relate to policy control. A more detailed discussion of the roles for each network element follows:
+  - The IPCablecom2 application manager is the entry point from the SIP network into the access network QoS system. The IPAM is in a position to apply policy which takes into consideration the limited service provided by the P-CSCF and potentially subscription based information.
+  - The Policy Server may receive messages from multiple application managers including but not limited to IPCablecom application managers. Policies applied at the PS can optimize the use of access network resources between multiple applications and traffic types.
+  - The CMTS is responsible for admission control and may have policies which control the allocation of resources between various types of traffic based on session class and possibly on the authorization model used such as IPCablecom and IPCablecom multimedia.
+
+In some cases, similar policy decisions could be made at more than one level in the network. The choice of at what level to implement a given policy will be based on such criteria as:
+
+- Access to required information.
+- Performance impacts of implementing policy at that level.
+- The ease of implementing policy at a given level.
+
+Ultimately, policy will be implemented at the level in the network which best furthers the business needs of the cable operator.
+
+### **II.7.4 Routing of QoS request**
+
+Assuming a P-CSCF to IPAM relationship as described in clause II.7.1.3, the routing of QoS requests is static, meaning that each P-CSCF is provisioned with a single AM (with the possibility of a secondary AM in the event of a failure) to which all its QoS requests are sent. If a multiple P-CSCF to multiple AM relationship is used, the routing of requests is outside the scope of this effort.
+
+The multimedia architecture is currently silent on how QoS requests are routed between the IPAM and PS and between the PS and CMTS. Given this gap, IPCablecom has defined a dynamic mechanism for PS to CMTS QoS message routing. This procedure is described in [ITU-T J.362] and is based on a path coupled query approach. Where a path coupled query approach is one where the query follows the same path through the network as any other packet destined for a given UE. This mechanism allows the PS to leverage the underlying routing protocols to ensure the proper CMTS is identified based on the IP address of the UE in question.
+
+The IPAM to PS routing of QoS requests is not defined in IPCablecom.
+
+## **II.8 Example procedures**
+
+This clause describes example operational behaviour based on the interfaces and requirements defined in IPCablecom. The Call flows provided in this clause are for reference only to facilitate understanding of the IPCablecom<sup>2</sup> QoS architecture.
+
+### **II.8.1 UE originated successful call**
+
+Figure II.4 illustrates a successful UE originated call flow. In the example below, the P-CSCF initiates the QoS process when it receives a SIP message with an SDP offer (usually an INVITE). The P-CSCF passes the SDP offer to the IPAM via the defined QoS interface. The IPAM is then able to translate the preliminary session needs into IPCablecom multimedia requests. This usually results in multiple IPCablecom multimedia gates being created (e.g., a standard audio call would have one upstream gate and one downstream gate).
+
+The IPAM generated IPCablecom multimedia request is then passed to the policy server for policy checks. These policy checks are usually done at the network level, meaning that the policy server ensures the request satisfies network based policies (the amount of resources being requested is within limits, the scheduling type is appropriate for the service, etc.). Once these requests pass the policy server checks, they are passed on to the CMTS for action.
+
+Upon receipt of the resource request, the CMTS is responsible for admission control and resource allocation. This process ensures that the CMTS has adequate resources to honour the request. Once the request has passed admission control and resource allocation, the CMTS installs the necessary flows and notifies the cable modem serving the UE via the DOCSIS defined dynamic service exchange (DSX) messaging interface. At this stage the resources are only reserved; they are not actually available for use. Rather, they have been allocated by the CMTS and can no longer be allocated to other services. Once the CM has been successfully notified of the resource allocation, the CMTS returns a flow identifier to the policy server, which then passes it back to the requesting IPAM.
+
+Once the P-CSCF receives the SDP answer, it has enough information about the remote party to commit the resources for the session. It does this by passing the SDP answer to the IPAM. The IPAM then (in conjunction with the SDP offer) translates this into a new IPCablecom multimedia request which updates the previously reserved resources. As long as the updated request is equal to or less than the reserved resources, it is essentially guaranteed to be granted.
+
+Once the resources are committed, the session can begin using the established flows and receive the desired QoS.
+
+Upon receipt of a BYE, the P-CSCF releases the resources associated with the session through a ReleaseQoSResources request.
+
+Figure II.4 illustrates an example of a UE originated successful call.
+
+![Sequence diagram showing a successful UE originated call with QoS reservation. Lifelines: UE A, CMTS, Policy server, IPAM, P-CSCF. The process involves INVITE, ReserveQoSRequest, Define connection parameters, Gate-Set*, ReserveQoSResponse, INVITE (SDP A), 180 RINGING, 200 OK (SDP B), CommitQoSRequest, Update connection parameters, Gate-Set* (Commit), Commit gate, CommitQoSResponse, 200 OK (SDP B), ACK, Two-way RTP media, BYE, ReleaseQoSRequest, Gate-Delete*, ReleaseQoSResponse, and BYE messages.](24ba47df8be44ae91945d88ce2232df5_img.jpg)
+
+```
+
+sequenceDiagram
+    participant UE A
+    participant CMTS
+    participant Policy server
+    participant IPAM
+    participant P-CSCF
+
+    Note right of Policy server: Define connection parameters
+    Note right of Policy server: Authorize gate
+    Note right of CMTS: Create gate
+    Note right of CMTS: Commit gate
+    Note right of CMTS: Delete gate
+
+    UE A->>P-CSCF: INVITE (SDP A)
+    P-CSCF->>IPAM: ReserveQoSRequest
+    IPAM->>Policy server: Define connection parameters
+    Policy server->>IPAM: Gate-Set* (reserve & authorize)
+    Policy server->>Policy server: Authorize gate
+    Policy server->>CMTS: Gate-Set* (reserve & authorize)
+    CMTS->>CMTS: Create gate
+    CMTS->>Policy server: Gate-Set-Ack*
+    Policy server->>IPAM: Gate-Set-Ack*
+    IPAM->>P-CSCF: ReserveQoSResponse
+    P-CSCF->>UE A: INVITE (SDP A)
+    P-CSCF->>UE A: 180 RINGING
+    P-CSCF->>UE A: 200 OK (SDP B)
+    P-CSCF->>IPAM: CommitQoSRequest
+    IPAM->>Policy server: Update connection parameters
+    Policy server->>IPAM: Gate-Set* (Commit)
+    Policy server->>CMTS: Gate-Set* (Commit)
+    CMTS->>CMTS: Commit gate
+    CMTS->>Policy server: Gate-Set-Ack*
+    Policy server->>IPAM: Gate-Set-Ack*
+    IPAM->>P-CSCF: CommitQoSResponse
+    P-CSCF->>UE A: 200 OK (SDP B)
+    P-CSCF->>UE A: ACK
+    P-CSCF->>UE A: Two-way RTP media
+    P-CSCF->>UE A: BYE
+    P-CSCF->>IPAM: ReleaseQoSRequest
+    IPAM->>Policy server: Gate-Delete*
+    Policy server->>CMTS: Gate-Delete*
+    CMTS->>CMTS: Delete gate
+    CMTS->>Policy server: Gate-Delete-Ack*
+    Policy server->>IPAM: Gate-Delete-Ack*
+    IPAM->>P-CSCF: ReleaseQoSResponse
+    P-CSCF->>UE A: BYE
+  
+```
+
+Sequence diagram showing a successful UE originated call with QoS reservation. Lifelines: UE A, CMTS, Policy server, IPAM, P-CSCF. The process involves INVITE, ReserveQoSRequest, Define connection parameters, Gate-Set\*, ReserveQoSResponse, INVITE (SDP A), 180 RINGING, 200 OK (SDP B), CommitQoSRequest, Update connection parameters, Gate-Set\* (Commit), Commit gate, CommitQoSResponse, 200 OK (SDP B), ACK, Two-way RTP media, BYE, ReleaseQoSRequest, Gate-Delete\*, ReleaseQoSResponse, and BYE messages.
+
+\* Indicates there may be one or more of these messages based on the session type.
+
+J.360\_FII.4
+
+**Figure II.4 – Example UE originated successful call**
+
+# Appendix III
+
+# IPCablecom2 security overview
+
+(This appendix does not form an integral part of this Recommendation)
+
+## III.1 Introduction
+
+The IPCablecom2 security architecture protects the data, interfaces and components that make up the IPCablecom2 architecture. This appendix describes the security relationships between the elements in the IPCablecom2 architecture.
+
+Design goals for the IPCablecom2 security architecture include:
+
+- Support for confidentiality, authentication, integrity, and access control mechanisms.
+- Protection of the network from denial of service, network disruption, theft-of-service attacks.
+- Protection of the UEs (i.e., clients) from denial of service attacks, security vulnerabilities, unauthorized access (from network).
+- Support for end-user privacy through encryption and mechanisms that control access to subscriber data such as presence information.
+- Mechanisms for device, UE, and user authentication, secure provisioning, secure signalling, and secure software download.
+- Leverage and extend the IMS security architecture in furtherance of the previously stated goals.
+
+## III.2 References
+
+This appendix uses the following additional informative references:
+
+- [ITU-T J.366.4] ITU-T Recommendation J.366.4 (2006), *IPCablecom2 IP Multimedia Subsystem (IMS): Session Initiation Protocol (SIP) and Session Description Protocol (SDP) – Stage 3 specification*. (3GPP TS 24.229)
+- [ITU-T J.366.7] ITU-T Recommendation J.366.7 (2006), *IPCablecom2 IP Multimedia Subsystem (IMS): Access security for IP-based services*. (3GPP TS 33.203)
+- [ITU-T J.366.8] ITU-T Recommendation J.366.8 (2006), *IPCablecom2 IP Multimedia Subsystem (IMS): Network domain security specification*. (3GPP TS 33.210)
+- [ITU-T J.366.9] ITU-T Recommendation J.366.9 (2006), *IPCablecom2 IP Multimedia Subsystem (IMS): Generic authentication architecture specification*. (3GPP TS 33.220)
+- [IETF RFC 1750] IETF RFC 1750 (1994), *Randomness Recommendations for Security*.
+- [IETF RFC 2246] IETF RFC 2246 (1999), *The TLS Protocol Version 1.0*.
+- [IETF RFC 2617] IETF RFC 2617 (1999), *HTTP Authentication: Basic and Digest Access Authentication*.
+- [IETF RFC 3268] IETF RFC 3268 (2002), *Advanced Encryption Standard (AES) Ciphersuites for Transport Layer Security (TLS)*.
+- [IETF RFC 3280] IETF RFC 3280 (2002), *Internet X.509 Public Key Infrastructure – Certificate and Certificate Revocation List (CRL) Profile*.
+
+|                   |                                                                                                                                                                                                                                               |
+|-------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| [IETF RFC 3310]   | IETF RFC 3310 (2002), <i>Hypertext Transfer Protocol (HTTP) Digest Authentication Using Authentication and Key Agreement (AKA)</i> .                                                                                                          |
+| [IETF RFC 3329]   | IETF RFC 3329 (2003), <i>Security Mechanism Agreement for the Session Initiation Protocol (SIP)</i> .                                                                                                                                         |
+| [IETF RFC 3489]   | IETF RFC 3489 (2003), <i>STUN – Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NATs)</i> .                                                                                                             |
+| [ID SIP-OUTBOUND] | <i>Managing Client Initiated Connections in the Session Initiation Protocol (SIP)</i> , <a href="http://www.ietf.org/internet-drafts/draft-ietf-sip-outbound-02.txt">http://www.ietf.org/internet-drafts/draft-ietf-sip-outbound-02.txt</a> . |
+| [ID TURN]         | <i>Obtaining Relay addresses from Simple Traversal of UDP Trough NAT (STUN)</i> , draft-ietf-behave-turn-00, March 2006.                                                                                                                      |
+| [TS 23.002]       | 3GPP TS 23.002 v6.10.0 (2005), <i>Network architecture</i> .                                                                                                                                                                                  |
+| [TS 33.222]       | 3GPP TS 33.222 v6.5.0 (2005), <i>Generic Authentication Architecture (GAA); Access to network application functions using Hypertext Transfer Protocol over Transport Layer Security (HTTPS)</i> .                                             |
+
+## III.3 Terms and definitions
+
+This appendix uses the following additional terms and definitions:
+
+**III.3.1 IM services identity module (ISIM):** The collection of IMS security data and functions on a UICC, may be a distinct application.
+
+**III.3.2 IPCablecom multimedia:** An application agnostic QoS architecture for services delivered over DOCSIS networks.
+
+## III.4 Abbreviations and acronyms
+
+This appendix uses the following additional abbreviations and acronyms:
+
+|        |                                      |
+|--------|--------------------------------------|
+| AKA    | Authentication and Key Agreement     |
+| BSF    | Bootstrapping Server Function        |
+| DDoS   | Distributed Denial of Service Attack |
+| DNSSEC | DNS Security                         |
+| DoS    | Denial of Service                    |
+| GBA    | Generic Bootstrapping Architecture   |
+| IDS    | Intrusion Detection System           |
+| MiM    | Man in the Middle                    |
+| PKI    | Public Key Infrastructure            |
+| SA     | Security Association                 |
+| UICC   | UMTS Integrated Circuit Card         |
+| USIM   | Universal Subscriber Identity Module |
+
+## III.5 IPCablecom2 security
+
+The IPCablecom2 security architecture describes the reference points and logical components and the data flows between these components.
+
+This clause provides:
+
+- A description of the relationship between IPCablecom2 and 3GPP IMS releases.
+
+- An overview of the IPCablecom2 architecture.
+- A description of the threats to the IPCablecom2 architecture.
+- A description of the IPCablecom2 security mechanisms.
+
+### III.5.1 Relationship with 3GPP IMS
+
+IP Cablecom2 is based on the IMS as defined by the 3rd Generation partnership Project (3GPP). 3GPP is a collaboration agreement between various standards bodies. The scope of 3GPP is to produce Technical Specifications and Technical Reports for GSM and 3rd generation (3G) mobile system networks.
+
+Within the overall IPCablecom goal to leverage existing industry standards whenever possible, there is a specific objective to align with the IMS architecture and specifications being developed by 3GPP. Specifically, IPCablecom2 will reuse many of the basic IMS functional entities and interfaces. Although this appendix discusses IMS, the main goal is to describe the enhancements and modifications to 3GPP specifications. Refer to [TS 23.002] for additional information on the 3GPP IMS architecture.
+
+### III.5.2 IPCablecom2 reference architecture
+
+An overview of the IPCablecom2 architecture elements and functional groupings is illustrated in Figure III.1.
+
+![A detailed block diagram of the IPCablecom2 reference architecture. The diagram is organized into several horizontal layers. At the top, the 'Interconnect' layer includes a 'Peer network' with a 'Border element' (containing an 'Interconnect proxy' and 'Media proxy'), a 'PSTN' connection via a 'PSTN GW' (with 'SG', 'MGC', 'MG' components) and 'BGCF', and 'PacketCable E-MTAs' connected to a 'CMS'. To the right, 'Operational support systems' include 'DNS', 'DHCP', 'Time', 'ENUM', 'PAC', 'NMS & EMS', and 'CDF'. The 'Core' layer contains 'SLF', 'HSS', 'I-CSCF', and 'S-CSCF'. The 'Application' layer includes a 'Presence server', 'Application server', and a 'Policy server' (part of the 'PacketCable multimedia server'). Below the core is the 'Edge' layer with 'TURN server', 'STUN server', 'P-CSCF', and 'PacketCable application manager'. The bottom 'Access network' layer features a 'CMTS' connected to a 'DOCSIS' network with multiple 'Cable modem' units. One modem connects to an 'E-MTA' and 'Cable modem' unit, which is further connected to a 'NAT & firewall' and then to a 'UE'. Other modems connect directly to 'UE' units. An 'Other' access point is also shown connected to a 'UE'. All 'UE' units are part of the 'Local network'.](86bd357c573c9696393f5bde4d4cce4f_img.jpg)
+
+A detailed block diagram of the IPCablecom2 reference architecture. The diagram is organized into several horizontal layers. At the top, the 'Interconnect' layer includes a 'Peer network' with a 'Border element' (containing an 'Interconnect proxy' and 'Media proxy'), a 'PSTN' connection via a 'PSTN GW' (with 'SG', 'MGC', 'MG' components) and 'BGCF', and 'PacketCable E-MTAs' connected to a 'CMS'. To the right, 'Operational support systems' include 'DNS', 'DHCP', 'Time', 'ENUM', 'PAC', 'NMS & EMS', and 'CDF'. The 'Core' layer contains 'SLF', 'HSS', 'I-CSCF', and 'S-CSCF'. The 'Application' layer includes a 'Presence server', 'Application server', and a 'Policy server' (part of the 'PacketCable multimedia server'). Below the core is the 'Edge' layer with 'TURN server', 'STUN server', 'P-CSCF', and 'PacketCable application manager'. The bottom 'Access network' layer features a 'CMTS' connected to a 'DOCSIS' network with multiple 'Cable modem' units. One modem connects to an 'E-MTA' and 'Cable modem' unit, which is further connected to a 'NAT & firewall' and then to a 'UE'. Other modems connect directly to 'UE' units. An 'Other' access point is also shown connected to a 'UE'. All 'UE' units are part of the 'Local network'.
+
+J.360\_FIII.1
+
+**Figure III.1 – IPCablecom reference architecture**
+
+The IPCablecom2 architecture is based on the IMS architecture, with the addition of some incremental extensions to support cable networks. These extensions include the use of additional or alternate components, as well as enhancements to capabilities provided by IMS functional components.
+
+Some of the major IPCablecom2 enhancements to the IMS include:
+
+- Support for quality of service for IMS-based applications on cable access networks, leveraging the IPCablecom multimedia architecture.
+- Support for signalling and media traversal of network address translation (NAT) and firewall (FW) devices, based on IETF mechanisms.
+- Support for the ability to uniquely identify and communicate with an individual when multiple UEs are registered under the same public identity.
+- Support for additional access signalling security and UE authentication mechanisms for IPCablecom UEs.
+- Support for provisioning, activation, configuration and management of IPCablecom UEs.
+
+IPCablecom2 includes both the existing IMS logical components and reference points, and logical elements and reference points added to support IPCablecom2 requirements.
+
+### **III.5.3 IPCablecom2 security threats**
+
+#### **III.5.3.1 General threats: Classification and analysis**
+
+Following is an overview of the general threats in the context of a generic IP multimedia communications architecture.
+
+##### **III.5.3.1.1 Trust domain threats**
+
+A trust domain is a logical grouping of network elements that are trusted to communicate in a manner consistent with a set of relevant security policies. Trust domains can be demarcated by physical or logical boundaries. Communication across trust domains must always be reviewed for authentication and authorization. Interfaces of interest for an IP multimedia infrastructure are:
+
+- Intra-network domain interfaces, which connect network elements within a service provider's domain. A compromise to any network element can be detrimental to the proper functioning of the network itself. Threats involve almost all the ones mentioned in this clause.
+- Inter-network domain interfaces, which connect two domains. The domains can be different service providers, or the same provider. Inter-domain trust levels can dictate the level of trust one can have within a domain (intra-domain), and hence, it is imperative that such interfaces be secured. Further, the security of two domains connected in such a manner relies on all the other connections established by each individual domain.
+- Access domain interfaces, which allow UEs to connect to a service provider. This set of interfaces is highly vulnerable to a multitude of security threats, largely due to the fact that access domains typically contain trusted as well as untrusted UEs and network elements. Strong authentication for any kind of network access would be vital for a service provider. If authentication is to be foregone, the services offered and the network elements to which such an unauthenticated access is provided should be minimized.
+
+##### **III.5.3.1.2 Theft of service**
+
+"Theft of Service" refers to a multitude of threats, including but not limited to:
+
+- Manipulation of the UE – UEs, especially software UEs, are vulnerable to Trojan attacks and manipulation of behaviour. Mitigation techniques include signed code and embedded UEs.
+
+- Protocol weakness exploitation – Exploitation of weak cryptographic measures can have a large impact, as it typically involves major redeployment. Mitigation techniques include defense in depth architecture.
+- Identity spoofing – The act of impersonating another user in order to gain access to services. This can lead to loss of credibility and revenue. Mitigation includes the use of strong authentication and user education.
+- UE cloning – The act of imitating a legitimate UE. This is typically an issue when UE identities are deemed sufficient to offer services, such as in architectures without the distinction of a 'user' and a 'client'. The recommendation would be to require UE credentials, to authenticate users before offering services, and to build infrastructures that can identify cloning and mitigate threats.
+- Subscription fraud and non-payment of services – Subscriptions established with falsified information and detection of non-payment are beyond the scope of this specification.
+
+##### III.5.3.1.3 Disruption and denial of service
+
+General DoS attacks aim to cause service interruption by crippling some or all service providing entities in the network. These attacks occur at layer 2 through layer 4 of the OSI reference model. Denial of service attacks focus on rendering a particular network element unavailable, using one of several different mechanisms. DoS attacks include:
+
+- Malformed message attacks – An attacker issues malformed messages that attempt to exploit a weakness in the robustness of a stack. Weaknesses include buffer overflows, or insufficient corner case and error handling. Mitigating this attack requires well-designed software protocol stacks and robustness testing.
+- Layer four depletion attacks – An attacker causes excessive state information to be consumed on a victim device, often in the context of state-aware protocol stacks. An example is a TCP-level attack such as a SYN flood, used to exhaust stack resources that keep track of session state. These attacks can be mitigated by intrusion detection systems (IDS) and firewalls, and by well-designed software protocol stacks and robustness testing.
+- Bearer-level flooding attacks – Denial of service attacks that focus on rendering a particular network element unavailable, usually by directing an excessive amount of media network traffic at its interfaces. Preventing this attack requires state-aware firewalls that open pinholes for media only if the trusted side of the firewall initiates the connection first. Flooding attacks often make use of spoofed source addresses to open firewall pinholes. Source address verification through 3-way handshakes can mitigate this threat. Quality of service (QoS) can also prevent excessive flows through a router.
+
+Flooding attacks generally make use of IP packets with spoofed source addresses. By preventing packets with spoofed addresses, some flooding attacks can be mitigated. There are several mechanisms to prevent address spoofing:
+
+- Use a challenge/response mechanism such as STUN or TURN.
+- Use of TCP makes source address verification easier (3-way handshake).
+- Unicast reverse path forwarding (uRPF) – Uses routing tables to determine whether the route to the source of the packet (the reverse path) is pointing to the interface the packet came in on.
+
+Zombie attacks consist of any type of denial of service attack that is launched from an authenticated endpoint. In addition, most zombie attacks make use of many zombies, resulting in a distributed denial of service attack (DDoS). Typically, a Trojan compromises an endpoint in order to leverage the endpoint's authentication. It is very difficult to defend against a zombie attack because the endpoint is authenticated and authorized. Zombie attacks can be thwarted by detecting anomalous traffic behaviour and filtering malicious traffic.
+
+##### **III.5.3.1.4 Signalling channel threats**
+
+In a multimedia environment such as a SIP architecture, signalling messages include data pertaining to identity, services, routing and other sensitive and critical data. Multimedia components such as proxies exist in the access domain, exposing them to a greater number of threats.
+
+Attacks on signalling security include:
+
+- Compromise of confidentiality – Signalling information, such as the caller identity and the services to which a customer subscribes may be vulnerable to discovery. The caller's identification information may also be used to locate the caller even if the caller wished to keep their location private.
+- Man in the middle (MiM) attacks – Attacks resulting from the interception and possible modification of traffic passing between two communication parties. These attacks are successful if the communicating parties cannot distinguish communications with the intended recipient from those of the attacker. Attacks, some of which are described in other clauses, include impersonating a proxy, undesired redirection, and loss of privacy due to MiM intervention.
+- Denial of service attacks – DoS attacks in the signalling channel range from the creation of bogus requests resulting in amplification attacks to falsifying routing headers. The use of multicast to transmit SIP requests greatly increases the potential for DoS attacks.
+
+Many of these threats can be mitigated by requiring mutual authentication, identity assertion, confidentiality, and integrity on the signalling plane.
+
+##### **III.5.3.1.5 Bearer channel threats**
+
+Threats to the bearer channel relate to the media traffic transferred between communicating parties.
+
+Attacks on bearer security include:
+
+- Compromise of confidentiality – Confidentiality in this sense is protection of the media messages themselves, which could be an audio session, instant messaging, or other multimedia message transfer. Depending on the security mechanism negotiated, end-to-end confidentiality may not be under the control of the sender.
+- Compromise of integrity – Modification, deletion, and replay are all possible attacks to the bearer channel.
+- Disruption attacks – As with any media technology, the ability of parties to communicate introduces unwanted communications. This category includes all the "normal" public switched telephone network (PSTN) attacks such as harassment, as well as some new threats relating to degradation and disruption of service in the IP model.
+
+Bearer channel attacks are mitigated by requiring mutual authentication, confidentiality and integrity on the bearer plane to prevent manipulation of data on the bearer plane, and ensuring privacy of sensitive information.
+
+##### **III.5.3.1.6 Reconnaissance**
+
+Well-planned attacks on service providers normally start with gaining reconnaissance on a network. Reconnaissance threats can be mitigated by using topology hiding mechanisms, including the introduction of border elements. Enforcing filtering techniques in the access domain allows for traffic policy enforcement at the edge of the network.
+
+##### **III.5.3.1.7 Roaming model considerations**
+
+Roaming models can minimize or add to security threats. UEs accessing services through alien environments can expose both the UE and the home network to greater risks. The trust relationship between the home and visited networks is enforced at the inter-domain security boundary.
+
+#### **III.5.3.2 Protocol specific security threats**
+
+The following clauses highlight threats to multimedia protocols. While this list does not include every multimedia protocol, it includes the major protocols discussed in the architecture and in later clauses.
+
+##### **III.5.3.2.1 SIP**
+
+Examples of attacks that can be performed from information gained by capturing SIP messages on the network include:
+
+- Tampering with message bodies (e.g., sending malformed SIP messages to disrupt a SIP network element; sending fake REGISTER messages to cause signalling messages to be redirected, rendering the hijacked UE unable to initiate or accept sessions).
+- Tearing down sessions (e.g., sending BYE or CANCEL messages to end a session prematurely).
+- Impersonating a server (e.g., sending false INVITEs).
+- Masquerading and faking server responses leading to service unavailability or denial of service (e.g., flooding the network with 302 Redirect or 401 Unauthorized messages).
+
+Some of the important vulnerabilities are explained in the following subclauses.
+
+###### **III.5.3.2.1.1 Registration hijacking**
+
+Registration hijacking involves a malicious endpoint that changes the registration of a different, existing endpoint, to point either back to the attacker, or to a different location. Registration hijacking can take several forms:
+
+- SIP endpoint cloning – An attacker user agent (UA) may attempt to register as an existing victim UE. The attacker UE becomes a "clone" of the victim UA, stealing the victim's identity.
+- Exploitation of weak identity – If a registrar assesses the identity of a UA, the 'From:' header of a SIP request can be arbitrarily modified and hence open to malicious registration.
+- Attackers could de-register some or all users in an administrative domain, thereby preventing these users from being invited to new sessions, resulting in a type of DoS attack.
+
+Refer to section 26.1.1 in [IETF RFC 3261] for more information about registration hijacking. The general method to prevent registration hijacking is to use secure identity assertion.
+
+###### **III.5.3.2.1.2 Faking user identity**
+
+Unless authenticated, SIP messages are vulnerable to identity spoofing. Fields such as 'From:' are not required to be filled and 'P-Asserted-Identity', unless populated by a trusted element securely, can be manipulated.
+
+Possible solutions to mitigate such a threat include:
+
+- Use strong credentials, and establish secure tunnels for message flows.
+- Use appropriate SIP Identity mechanism like "SIP identity" that supports cryptographically verifiable assertions.
+
+###### **III.5.3.2.1.3 Malformed SIP messages**
+
+An attacker can issue malformed SIP messages that attempt to exploit a weakness in the robustness of a SIP stack or the protocol itself. Weaknesses include unwarranted DoS initiation, buffer overflows, or insufficient corner case handling. Mitigating this attack requires stack robustness testing. Specific scenarios that lead to DoS attacks include:
+
+- Using falsified Via header fields identifying a targeted host as the originator of the request and then sending these requests to a large number of SIP network elements.
+- Using falsified Route headers in a request that identify the target host and then sending such messages to forking proxies that will amplify messaging sent to the target.
+
+SIP proxy servers by nature accept requests from varied IP endpoints, and are consequently exposed to an increased number of threats.
+
+###### **III.5.3.2.1.4 SIP message storms**
+
+SIP message storms can consist of sending random SIP messages so that memory or processing power is exhausted by exhausting state storage or requiring encryption steps, respectively. SIP message storms can happen either from within a network, or from the outside. Mitigation techniques to thwart such attacks include:
+
+- Debugging stacks for resource depletion.
+- Use of anti-replay countermeasures.
+- Avoiding multiple responses to a single event (e.g., multiple 401 messages for authentication challenge).
+- Detecting storms and using appropriate filters to shutdown misbehaving UEs.
+
+Message storms may arise from registration floods, where a large number of endpoints attempt to register, but fail authentication at the edge of the network and bog down the edge proxies. In addition, edge proxies may allow endpoints to register without authentication, and then defer the UE challenge to servers internal to the network, in which case the internal servers are susceptible to DoS floods. There are several ways to mitigate these types of attacks:
+
+- Require authentication at the edge proxies, to spread the load of authentication and better defend against registration DoS floods.
+- Impose flood-control measures – provide a nonce to UEs that authenticate for the first time, which can be used later, under less strict rate limiting.
+- Allow the P-CSCF to prioritize signalling, based on previously successful challenges from the same UE.
+
+###### **III.5.3.2.1.5 Session hijacking**
+
+Methods of launching a session hijacking attack include the following:
+
+- Modification of SDP information.
+- Using messages like "301 moved permanently" to redirect INVITEs to another location (assuming the attacker knows Call-ID, To, From, Cseq fields).
+
+The general method to prevent session hijacking is to require authentication of all SIP messages.
+
+###### **III.5.3.2.1.6 Impersonating a server**
+
+SIP servers may be impersonated in the network by an attacker. SIP server impersonation can result in a DoS or privacy breach. It presents a possibly greater problem when SIP mobility is considered. The general method to prevent impersonation is server authentication by UAs.
+
+Refer to section 26.1.2 in [IETF RFC 3261] for more information.
+
+###### **III.5.3.2.1.7 Tampering with message bodies**
+
+Refer to section 26.1.3 in [IETF RFC 3261] for more information.
+
+###### **III.5.3.2.1.8 Tearing down sessions**
+
+Refer to section 26.1.4 in [IETF RFC 3261] for more information.
+
+###### **III.5.3.2.1.9 Reconnaissance threats**
+
+Certain SIP messages and fields facilitate reconnaissance threats. Mitigation of such threats can be facilitated by preventing the usage of certain fields (e.g., OPTIONS) in messages.
+
+##### **III.5.3.2.2 STUN**
+
+In general, attacks on STUN can be classified into denial of service attacks and eavesdropping attacks. Denial of service attacks can be launched against a STUN server itself, or against other elements using the STUN protocol.
+
+Many of the attacks require the attacker to generate a response to a legitimate STUN request, in order to provide the UE with a faked MAPPED-ADDRESS. The attacks that can be launched using such a technique include:
+
+- DDoS against a target.
+- Silencing a UE.
+- Assuming the identity of a UE.
+- Eavesdropping.
+
+More detailed information on these attacks and how the threats are addressed by the STUN protocol itself can be found in [IETF RFC 3489].
+
+##### **III.5.3.2.3 TURN**
+
+A TURN server acts as a redirector, to funnel media streams through a NAT to a destination. A TURN server therefore has the potential to become a source for a DoS attack that utilizes high-bandwidth media streams. Critical to preventing misuse of a TURN server is a cryptographically verifiable way of establishing an authentication and authorization mechanism to allow recipients of media streams to authorize the TURN server to forward media.
+
+##### **III.5.3.2.4 TLS**
+
+Because transport layer security (TLS) is hop-by-hop, it may be compromised within a server that terminates and re-originates signalling.
+
+TLS also relies on a mechanism to establish trust between two communicating entities, such as a public key infrastructure (PKI) within an administrative domain. TLS establishment between servers should involve mutual authentication.
+
+TLS generally relies on transitive trust for hop-by-hop security. If each endpoint has its own local server, and the servers trust each other, then the endpoints can assume through transitive trust that the end-to-end communication is secure.
+
+##### **III.5.3.2.5 HTTP Digest**
+
+The primary threat posed to HTTP-Digest authentication involves a MiM (man in the middle) attack. HTTP Digest operates by verifying that a user has a pre-shared password. After the UE requests access to a resource, the server challenges the UE for a password. In the challenge, the server sends down a nonce in the clear that should be used by the UE to generate a securely formed hash of the password. The hashed password is sent to the server in the clear. This method of authentication is susceptible to a MiM using a dictionary attack, in an attempt to find a password
+
+that results in the same secure hash as the value sent back to the server. Consequently, HTTP Digest should be used over secure data paths.
+
+##### **III.5.3.2.6 DNS**
+
+The domain name system in general is insecure without the use of DNSSEC. Possible security threats include manipulation of request or response queries leading to redirection or denial of service, and usage of dynamic DNS functionality, if enabled, to manipulate DNS servers and reflect incorrect topologies.
+
+To mitigate some of these threats, DNS should only be used for general information and other configuration mechanisms, such as authentication, used to validate network elements.
+
+##### **III.5.3.2.7 Software-based UEs**
+
+IPCablecom support software-based UEs to authenticate and use network services. Software-based UEs present challenges that lead to vulnerabilities:
+
+- Even though software-based UEs may have a provision to connect to a secure hardware keystore, such as a smart card, they generally store credentials in unprotected storage.
+- The software image on a soft UE is not tamper-proof.
+- Applications on software-based UEs may store a user's password for later automated entry.
+
+### **III.5.4 IPCablecom2 security architecture overview**
+
+This clause describes the IPCablecom2 security architecture, including enhancements to the IMS. The trust domains described in clause III.5.3 are used to decompose the IPCablecom2 architecture. Each trust domain is discussed in further detail in the following clauses.
+
+#### **III.5.4.1 Access domain**
+
+UEs connect to the network through the access domain. Interfaces and components present in the access domain are shown in Figure III.2.
+
+![Diagram of Access domain reference points showing UE connections to various network elements through the Access domain. The diagram is divided into four main sections: NAT (pkt-nat-1, pkt-nat-2), PACM (pkt-pacm-1 to pkt-pacm-6), Signalling (Gm), and Media (Mb). Each section is connected to specific external servers: TURN and STUN for NAT; DHCP, DNS, PAC (PDS/XDS), Time, and EMS & NMS for PACM; P-CSCF for Signalling; and Media and Application servers for Media. Two User Equipment (UE) blocks are shown on the left, connected by an Mb interface.](9c80cf99954eb0142f694456d39fae4b_img.jpg)
+
+J.360\_FIII.2
+
+Diagram of Access domain reference points showing UE connections to various network elements through the Access domain. The diagram is divided into four main sections: NAT (pkt-nat-1, pkt-nat-2), PACM (pkt-pacm-1 to pkt-pacm-6), Signalling (Gm), and Media (Mb). Each section is connected to specific external servers: TURN and STUN for NAT; DHCP, DNS, PAC (PDS/XDS), Time, and EMS & NMS for PACM; P-CSCF for Signalling; and Media and Application servers for Media. Two User Equipment (UE) blocks are shown on the left, connected by an Mb interface.
+
+**Figure III.2 – Access domain reference points**
+
+UE interactions with the network occur in the access domain. Access methods are varied, and include DOCSIS and wireless. Due to these characteristics, the access domain is home to a multitude of threats, as described in clause III.5.3.
+
+Table III.1 provides a high-level overview of the security architecture that results from the IPCablecom2 enhancements to IMS. Each access domain reference point, along with the security mechanism employed for that interface, are included.
+
+**Table III.1 – Access domain reference points description**
+
+| Reference point | IPCablecom2 network elements | Reference point security description                                                  |
+|-----------------|------------------------------|---------------------------------------------------------------------------------------|
+| pkt-nat-1       | UE – TURN server             | TURN: TURN requests are authenticated and authorized within the TURN protocol itself. |
+| pkt-nat-2       | UE – External STUN server    | STUN: Message integrity is provided by STUN mechanisms.                               |
+| pkt-pacm-1      | UE – DHCP server             | DHCP: IPCablecom2 does not define security for the DHCP protocol.                     |
+| pkt-pacm-2      | UE – DNS server              | DNS: IPCablecom2 does not define security for the DNS protocol.                       |
+
+**Table III.1 – Access domain reference points description**
+
+| Reference point | IPCablecom2 network elements                          | Reference point security description                                                                                                                                                                                   |
+|-----------------|-------------------------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| pkt-pacm-3      | UE – PDS server                                       | SIP: Message integrity and privacy via IPSec or TLS.                                                                                                                                                                   |
+| pkt-pacm-4      | UE – XDS server                                       | XCAP: Message integrity and privacy via HTTP over TLS.                                                                                                                                                                 |
+| pkt-pacm-5      | UE – Time server                                      | SNTP: IPCablecom2 does not define security for the SNTP protocol.                                                                                                                                                      |
+| pkt-pacm-6      | UE – EMS & NMS server                                 | Management interface security is out of scope for this specification.                                                                                                                                                  |
+| Gm              | UE – P-CSCF                                           | SIP: Message integrity and privacy via IPSec or TLS.<br>STUN: Message integrity is provided by STUN mechanisms (as STUN requests are sent to the standard SIP port, P-CSCF must logically contain STUN functionality). |
+| Mb              | UE – UE<br>UE – Media server<br>UE – MG<br>UE – E-MTA | RTP: Media security is out of scope for this specification.                                                                                                                                                            |
+
+#### III.5.4.2 Intra-network domain
+
+Intra-domain reference points and components are contained within a service provider's network, and consequently, a holistic security policy.
+
+IMS defines the security of intra-domain connections with the Zb interface, as described in [ITU-T J.366.8]. Within IMS, integrity is required and confidentiality is optional when the Zb interface is implemented. IPSec ESP is used to provide security services for the Zb interface between intra-domain components.
+
+IPCablecom enhances the Zb interface by adding TLS to provide security services for intra-domain TCP data flows. Clause III.6.6 describes the Zb reference point TLS requirements.
+
+#### III.5.4.3 Inter-network domain
+
+Inter-domain reference points connect the operator security domain with external partners and networks. These connections provide interworking between the operator's network and other service providers and networks, including the PSTN. Figure III.3 shows the inter-domain trust boundary.
+
+![Diagram illustrating Inter-network domain reference points between Intra-domain and Inter-domain networks. A vertical line separates the two domains. On the Intra-domain side, there are three boxes: 'Border element' (containing 'Interconnect proxy' and 'Media proxy'), 'PSTN GW' (containing 'SGW', 'MGCF', and 'MGW'), and 'CMS'. On the Inter-domain side, there are labels 'IP', 'PSTN', and 'PacketCable' corresponding to the connections from the Intra-domain elements. The diagram is labeled J.360_FIII.3 at the bottom.](7ec36a0a9788e1cb33df5372695498c8_img.jpg)
+
+Diagram illustrating Inter-network domain reference points between Intra-domain and Inter-domain networks. A vertical line separates the two domains. On the Intra-domain side, there are three boxes: 'Border element' (containing 'Interconnect proxy' and 'Media proxy'), 'PSTN GW' (containing 'SGW', 'MGCF', and 'MGW'), and 'CMS'. On the Inter-domain side, there are labels 'IP', 'PSTN', and 'PacketCable' corresponding to the connections from the Intra-domain elements. The diagram is labeled J.360\_FIII.3 at the bottom.
+
+**Figure III.3 – Inter-network domain reference points**
+
+IMS defines the security of inter-domain connectivity with the Za interface, as described in [ITU-T J.366.8]. Both integrity and confidentiality are required for the Za interface, based on IPSec ESP. Inter-domain traffic in IMS is required to pass through a security gateway (SEG). The SEG terminates reference point Za IPSec tunnels and enforces security policy on inter-domain traffic flows. Figure III.3 shows an architecture including the SEG functionality in the border element, but the SEG may be a separate element.
+
+The PSTN gateway to PSTN reference point is secured using PSTN security mechanisms.
+
+IP Cablecom2 adds support for inter-networking to IP Cablecom networks. The call management server (CMS) provides translation for IP Cablecom messaging. Security for the CMS reference point is detailed in [ITU-T J.170].
+
+## III.6 IP Cablecom security requirements
+
+The following clauses describe the IP Cablecom2 enhancements to the IMS security architecture.
+
+### III.6.1 User and UE authentication
+
+3GPP IMS relies completely on credentials stored in a UMTS integrated circuit card (UICC) for access security. The UICC is a platform for security applications used for authentication and key agreement. IP Cablecom has a requirement to support multiple types of UEs, such as software UEs, which will not contain or have access to UICCs.
+
+[ITU-T J.366.7] describes the IMS approach to authentication and establishing transport security between the UE and the P-CSCF. The IMS uses a combination of IPSec for integrity and optional confidentiality, and IMS-AKA for authentication. To meet the IMS requirements of minimal round trips, the security elements of the negotiation "piggy-back" on the SIP register messaging flow. [IETF RFC 3329] is used to negotiate security between the UE and the P-CSCF, and IMS-AKA [IETF RFC 3310] is used between the UE and the S-CSCF to perform mutual authentication. [IETF RFC 2617] is extended to pass authentication data from the UE to the S-CSCF. The communications between the UE and the P-CSCF and the communications between the UE and the S-CSCF are related in that the keying material for the security associations between the UE and the P-CSCF are computed from the long-term shared secret stored in the home subscriber server (HSS)
+
+and the UICC in the UE. Figure III.4 shows the high-level message flows for authentication during registration. Some elements and messages are not displayed in order to simplify discussion.
+
+![Sequence diagram of IMS registration message flow between UE, P-CSCF, S-CSCF, and HSS.](6f46eccb86e008f8bc7af8ea3ab806a7_img.jpg)
+
+```
+
+sequenceDiagram
+    participant UE
+    participant P-CSCF
+    participant S-CSCF
+    participant HSS
+
+    Note left of UE: (1) Register
+    UE->>P-CSCF: Register
+    Note right of P-CSCF: Security-Client=ipsec-3gpp  
+Authorization: 'privateID'  
+Require: sec-agree
+    Note left of S-CSCF: (2) Register
+    P-CSCF->>S-CSCF: Register
+    Note right of S-CSCF: Security-Client, sec-agree stripped  
+Authorization: 'privateID', integrity-protected=no
+    Note left of HSS: (3) Cx
+    S-CSCF->>HSS: Cx
+    Note right of HSS: S-CSCF retrieves AV(s) for privateID, updates S-CSCF URI
+    Note left of S-CSCF: (4) Cx
+    HSS->>S-CSCF: Cx
+    Note left of P-CSCF: (5) 401 Unauthorized
+    S-CSCF->>P-CSCF: 401 Unauthorized
+    Note right of P-CSCF: www-authenticate: nonce, algorithm
+    Note left of UE: (6) 401 Unauthorized
+    P-CSCF->>UE: 401 Unauthorized
+    Note right of UE: Security-Server: ipsec-3gpp;  
+www-authenticate: nonce, algorithm  
+  
+Client computes CK/IK from RAND/AUTH (network authentication)
+    Note left of UE: IPsec SA
+    UE->>P-CSCF: IPsec SA
+    Note right of P-CSCF: IPsec SA
+    P-CSCF->>UE: IPsec SA
+    Note right of UE: Client computes RES for client authentication
+    Note left of UE: (7) Register
+    UE->>P-CSCF: Register
+    Note right of P-CSCF: Security-Verify=ipsec-3gpp  
+Authorization: 'privateID', nonce, RES  
+Require: sec-agree
+    Note left of S-CSCF: (8) Register
+    P-CSCF->>S-CSCF: Register
+    Note right of S-CSCF: Security-Client, sec-agree stripped  
+Authorization: 'privateID', integrity-protected=yes
+    Note left of HSS: (9) Cx
+    S-CSCF->>HSS: Cx
+    Note left of HSS: (10) Cx
+    HSS->>S-CSCF: Cx
+    Note left of P-CSCF: (11) 200 OK
+    S-CSCF->>P-CSCF: 200 OK
+    Note left of UE: (12) 200 OK
+    P-CSCF->>UE: 200 OK
+    Note right of P-CSCF: P-CSCF inserts P-Asserted-Identity in subsequent messages
+  
+```
+
+Sequence diagram of IMS registration message flow between UE, P-CSCF, S-CSCF, and HSS.
+
+J.360\_FIII.4
+
+**Figure III.4 – IMS registration message flow**
+
+For authentication during registration, the following basic steps occur:
+
+- 1) The UE sends a register request to the P-CSCF. The message includes an [IETF RFC 3329] security-client header which includes the security mechanisms the UE supports. IMS mandates 'ipsec-3gpp'. The message also includes an authorize header which includes the private identity of the subscriber.
+- 2) The P-CSCF strips the security agreement headers, inserts 'integrity-protected=no' in the authorized header, and forwards the register request to the appropriate I-CSCF, which forwards the request to the appropriate S-CSCF of the subscriber's home network.
+- 3) The S-CSCF contacts the HSS to update the S-CSCF URI for that user, and if necessary, requests one or more authentication vectors.
+- 4) The HSS returns one or more authentication vectors if requested. The authentication vectors provide the necessary data for the S-CSCF to create a www-authenticate header and challenge the user.
+
+- 5) The S-CSCF creates and sends a SIP 401 (Unauthorized) response, containing a www-authenticate header that includes a challenge. This response is routed back to the P-CSCF.
+- 6) The P-CSCF strips the integrity key (IK) and the confidentiality key (CK) from the 401 response to use for IPSec SAs between the P-CSCF and the UE, and sends the rest of the response to the UE.
+- 7) Upon receiving the challenge message, the UE determines the validity of the received authentication challenge. The UE sets up security associations with the P-CSCF using the IK and CK that was derived from the data sent by the HSS, utilizing the long-term shared key in its UICC. The UE then calculates a response (RES) and sends a second register request with an authorization header including the challenge response. This message includes Security-Verify headers as per [IETF RFC 3329].
+- 8) The P-CSCF strips the security agreement headers, inserts 'integrity-protected=yes' in the authorize header, and forwards to the appropriate I-CSCF which forwards to the appropriate S-CSCF.
+- 9) The S-CSCF compares the authentication challenge response received from the UE with the expected response received from the HSS. If they match, the S-CSCF updates HSS data using the Cx interface.
+- 10) The HSS provides the S-CSCF with subscriber data over the Cx interface, including service profiles, which contain initial filter criteria.
+- 11) The S-CSCF forwards a 200 OK response to the UE. The 200 OK contains a P-Associated-URI header which includes the list of public user identities that are associated to the public user identity under registration.
+- 12) The P-CSCF forwards the 200 OK to the UE. Because the user has now been authenticated and there is an existing security association between the P-CSCF and the UE, the P-CSCF inserts a P-Asserted-Identity header in all subsequent messages from that UE.
+
+IPCablecom has requirements to support UEs and authentication schemes not considered in the IMS architecture, as well as additional transport security mechanisms. IPCablecom2 enhances the IMS specifications in several areas in order to support these requirements.
+
+#### III.6.1.1 Description
+
+The IPCablecom2 architecture supports the following authentication mechanisms:
+
+- IMS AKA.
+- SIP digest authentication.
+- Certificate-based authentication.
+
+The architecture must also accommodate UEs with multiple authentication credentials. For example, a UE may have a certificate for accessing services while on a cable network, and a UICC for accessing services while on a cellular network.
+
+A subscriber may have multiple credentials for the same private identity. A subscriber may have multiple UEs, with different capabilities related to those credentials. For example, a subscriber may have an MTA with a certificate for home use, and a UICC-based UE for travelling.
+
+##### III.6.1.1.1 IMS AKA
+
+IMS AKA authentication with UICC credentials will continue to operate as described in 3GPP specifications.
+
+##### III.6.1.1.2 SIP digest authentication
+
+IPCablecom2 supports SIP authentication as described in [IETF RFC 3261]. SIP authentication uses a challenge-response framework for authentication of SIP messages and access to services. In this approach, a user is challenged to prove their identity, either during registration or during other SIP dialogues initiations.
+
+SIP authentication in IPCablecom2 is handled in a similar manner to IMS AKA, and follows [IETF RFC 3261] and [IETF RFC 2617]. This approach minimizes impact to the existing IMS authentication flow by maintaining existing headers and round trips. Unlike IMS AKA, however, challenges are not precomputed. In order to maximize the security of SIP digest authentication, cnonces and qop "auth-int" directives are used, which requires challenges to be computed in real-time at the S-CSCF.
+
+Figure III.5 shows the message flow for SIP based authentication during a registration.
+
+![Sequence diagram of SIP digest authentication during registration. The diagram shows four vertical lifelines: UE, P-CSCF, S-CSCF, and HSS. 1. UE sends (1) Register to P-CSCF with Authorization: 'privateID', algorithm=MD5. 2. P-CSCF forwards (2) Register to S-CSCF. 3. S-CSCF sends (3) MAR-Cx to HSS. 4. HSS retrieves AV(s) for privateID and updates S-CSCF URI, then sends (4) MAA-Cx back to S-CSCF with Authentication-scheme=HTTP_Digest_MD5, AV=nonce, domain, opaque, stale?, algorithm, QOP=auth/auth-int, HA1. 5. S-CSCF sends (5) 401 Unauthorized to P-CSCF with www-authenticate: realm, nonce, qop, opaque, algorithm. 6. P-CSCF forwards (6) 401 Unauthorized to UE. 7. UE computes digest response per RFC 2617 and sends (7) Register to P-CSCF with Authorization: 'privateID', nonce, qop, nc, cnonce, response, opaque. 8. P-CSCF forwards (8) Register to S-CSCF. 9. S-CSCF sends (9) SAR-Cx to HSS. 10. HSS sends (10) SAA-Cx to S-CSCF. 11. S-CSCF sends (11) 200 OK to P-CSCF with Authentication-info: qop, rspauth (equals response), cnonce, nc. 12. P-CSCF forwards (12) 200 OK to UE. 13. UE validates authentication-info values.](da06747b80ea0d71593cbbd4c2ea89aa_img.jpg)
+
+```
+
+sequenceDiagram
+    participant UE
+    participant P-CSCF
+    participant S-CSCF
+    participant HSS
+
+    UE->>P-CSCF: (1) Register
+    Note over UE,P-CSCF: Authorization: 'privateID',  
+algorithm=MD5
+    P-CSCF->>S-CSCF: (2) Register
+    Note over P-CSCF,S-CSCF: Authorization: 'privateID',  
+algorithm=MD5
+    S-CSCF->>HSS: (3) MAR-Cx
+    Note right of HSS: S-CSCF retrieves AV(s) for  
+privateID, updates S-CSCF URI
+    HSS->>S-CSCF: (4) MAA-Cx
+    Note over S-CSCF,HSS: Authentication-  
+scheme=HTTP_Digest_MD5,  
+AV=nonce, domain, opaque,  
+stale?, algorithm, QOP=auth/  
+auth-int, HA1
+    S-CSCF->>P-CSCF: (5) 401 Unauthorized
+    Note over P-CSCF,S-CSCF: www-authenticate: realm,  
+nonce, qop, opaque, algorithm
+    P-CSCF->>UE: (6) 401 Unauthorized
+    Note over UE,P-CSCF: www-authenticate: realm,  
+nonce, qop, opaque, algorithm
+    Note left of UE: Client computes digest  
+response per RFC 2617 for  
+client authentication
+    UE->>P-CSCF: (7) Register
+    Note over UE,P-CSCF: Authorization: 'privateID',  
+nonce, qop, nc, cnonce,  
+response, opaque
+    P-CSCF->>S-CSCF: (8) Register
+    Note over P-CSCF,S-CSCF: Authorization: 'privateID',  
+nonce, qop, nc, cnonce,  
+response, opaque
+    S-CSCF->>HSS: (9) SAR-Cx
+    HSS->>S-CSCF: (10) SAA-Cx
+    S-CSCF->>P-CSCF: (11) 200 OK
+    Note over P-CSCF,S-CSCF: Authentication-info: qop,  
+rspauth (equals response),  
+cnonce, nc
+    P-CSCF->>UE: (12) 200 OK
+    Note over UE,P-CSCF: Authentication-info: qop,  
+rspauth (equals response),  
+cnonce, nc
+    Note left of UE: Client validates  
+authentication-info values
+
+```
+
+Sequence diagram of SIP digest authentication during registration. The diagram shows four vertical lifelines: UE, P-CSCF, S-CSCF, and HSS. 1. UE sends (1) Register to P-CSCF with Authorization: 'privateID', algorithm=MD5. 2. P-CSCF forwards (2) Register to S-CSCF. 3. S-CSCF sends (3) MAR-Cx to HSS. 4. HSS retrieves AV(s) for privateID and updates S-CSCF URI, then sends (4) MAA-Cx back to S-CSCF with Authentication-scheme=HTTP\_Digest\_MD5, AV=nonce, domain, opaque, stale?, algorithm, QOP=auth/auth-int, HA1. 5. S-CSCF sends (5) 401 Unauthorized to P-CSCF with www-authenticate: realm, nonce, qop, opaque, algorithm. 6. P-CSCF forwards (6) 401 Unauthorized to UE. 7. UE computes digest response per RFC 2617 and sends (7) Register to P-CSCF with Authorization: 'privateID', nonce, qop, nc, cnonce, response, opaque. 8. P-CSCF forwards (8) Register to S-CSCF. 9. S-CSCF sends (9) SAR-Cx to HSS. 10. HSS sends (10) SAA-Cx to S-CSCF. 11. S-CSCF sends (11) 200 OK to P-CSCF with Authentication-info: qop, rspauth (equals response), cnonce, nc. 12. P-CSCF forwards (12) 200 OK to UE. 13. UE validates authentication-info values.
+
+J.360\_FIII.5
+
+**Figure III.5 – SIP digest authentication**
+
+For SIP digest authentication during registration, the following basic steps occur. [IETF RFC 3329] headers and other SIP header contents are not shown for simplicity.
+
+- 1) The UE sends a register request to the P-CSCF. The message includes an authorization header which includes the private identity of the subscriber. An example authorization header is shown below:
+
+```
+REGISTER sip:home.atlanta.com SIP/2.0
+Authorization: Digest username="alice_private@atlanta.com",
+               realm="atlanta.com", nonce="", uri="sip:home.atlanta.com",
+               response="", algorithm="MD5"
+```
+
+IP Cablecom adds the algorithm parameter to the initial IMS register message in order to inform the network what type of challenge to create. This is to support multiple credential types per user.
+
+- 2) The P-CSCF forwards the register request to the appropriate I-CSCF, which forwards the request to the appropriate S-CSCF of the subscriber's home network.
+- 3) The S-CSCF contacts the HSS using a MAR command towards the HSS on the Cx interface. The MAR message includes the private identity of the subscriber, the S-CSCF information, and the number of authentication vectors requested. This information is used by the HSS to update the S-CSCF URI for the private identity and to deliver the correct authentication vector information to the S-CSCF.
+- 4) The HSS returns a MAA message on the Cx interface. The MAA message includes the public identities and authentication vectors for that subscriber. The contents of the authentication vector for SIP digest are detailed in a later clause. The main differences are the lack of a CK and IK, and the contents of the SIP-Authenticate data element. Instead of AKA data, the SIP-Authenticate AVP contains data the S-CSCF requires for computing a Digest response, primarily HA1.
+- 5) The S-CSCF creates a SIP 401 (Unauthorized) response, which includes a challenge in the www-authenticate header field, and other [IETF RFC 3261] fields. An example header is shown below:
+
+```
+SIP/2.0 401 Unauthorized
+WWW-Authenticate: Digest realm="atlanta.com",
+                  nonce="CjPk9mRqNuT25eRkajM09uTl9nM09uTl9nMz5OX25PZz==",
+                  qop=auth,auth-int, opaque="5ccc069c403ebaf9f0171e9517f40e41",
+                  algorithm="MD5"
+```
+
+Details on nonce creation are described in a later clause. Based on local policy, the server sends back the qop parameters the client must choose from.
+
+- 6) This response is routed back to the P-CSCF, and then to the UE.
+- 7) Once the UE receives the challenge, the UE calculates the response based on items in the WWW-Authenticate header and additional items (e.g., cnonce) generated by the UE. The values in the Authorize header are calculated as per [IETF RFC 3261], and thus [IETF RFC 2617]. The qop value is selected from the choices provided by the S-CSCF. cnonce values are computed as described in a later clause. The UE sends a second register request with the Authorization header. An example Authorization header is shown below:
+
+```
+REGISTER sip:home.atlanta.com SIP/2.0
+Authorization: Digest
+               username="alice_private@atlanta.com", realm="atlanta.com",
+               nonce="CjPk9mRqNuT25eRkajM09uTl9nM09uTl9nMz5OX25PZz==",
+               uri="sip:home.atlanta.com", qop=auth-int, nc=00000001,
+               cnonce="0a4f113b",
+               response="6629fae49393a05397450978507c4ef1",
+               opaque="5ccc069c403ebaf9f0171e9517f40e41", algorithm="MD5"
+```
+
+- 8) The P-CSCF forwards the message to the appropriate I-CSCF which forwards to the appropriate S-CSCF.
+- 9) Upon receiving the second register from the UE, the S-CSCF calculates the challenge in the same manner as the UE, in order to compare the two results and thus authenticate the subscriber. Using parameters from the HSS such as HA1, and the parameters from the Authorization header such as cnonce, the S-CSCF computes the challenge response as per [IETF RFC 3261] and thus [IETF RFC 2617]. The computation is performed in a manner consistent with the qop parameter sent by the UE.
+
+If the two challenge results are identical, the S-CSCF performs a SAR procedure on the Cx interface, informing the HSS the user is registered and requesting the user profile.
+
+- 10) The HSS returns a SAA message to the S-CSCF containing the user profile, which includes, among other things, the collection of all the public user identities allocated for authentication of the private user identity, as well as the initial filter criteria.
+- 11) The S-CSCF sends a 200 OK response to the register request. The response includes an Authentication-Info header, which allows the UE to authenticate the network, or S-CSCF. The rspauth value is calculated per [IETF RFC 2617]. The header also includes a nextnonce value. The 200 OK message is forwarded to the UE. An example Authentication-Info header is shown below:
+
+```
+SIP/2.0 200 OK
+    Authentication-Info:
+    qop=auth-int, rspauth="7729fae49393a05397450978507c4ef1",
+    cnonce="0a4f113b", nc=00000001,
+    nextnonce="8829fae49393a05397450978507c4ef1"
+```
+
+- 12) The 200 OK is routed to the appropriate P-CSCF, and then to the UE.
+- 13) The UE validates the rspauth value, to authenticate the network, or S-CSCF.
+
+Because the user has now been authenticated and there is an existing security association between the P-CSCF and the UE, the P-CSCF inserts a P-Asserted-Identity header in all subsequent messages from that UE.
+
+Adding support for SIP digest impacts the IMS specifications in the following ways:
+
+- New digest algorithms are allowed to be present in the www-authenticate and authorization headers.
+- The HSS must compute and store new types of digest responses.
+- UEs must be able to support and compute new types of digest responses.
+- The home network (or S-CSCF) authenticates to the UE by including an Authentication-Info header in the 2xx response following a successful authentication of the UE.
+
+Impacts to specific components are discussed in clause III.6.1.2.
+
+##### III.6.1.1.3 Certificate-based
+
+Certificate-based authentication is out of scope for this version of this appendix.
+
+#### III.6.1.2 Impacted components
+
+The following clauses describe the impacts to IMS components in order to accommodate IPCablecom authentication requirements.
+
+##### III.6.1.2.1 UE
+
+In order to support new forms of authentication, IPCablecom UEs must send the appropriate 'algorithm' parameter in initial register requests.
+
+IP Cablecom UEs supporting digest authentication must conform to [IETF RFC 3261], and thus [IETF RFC 2617]. UEs must send the 'algorithm' parameter set to the appropriate digest algorithm in the initial register request. Upon receiving a challenge from the S-CSCF in a 401 Unauthorized message, UEs must create an authorization header including a challenge response as described in [IETF RFC 2617] based on the algorithm parameter in the www-Authenticate header. cnonce and nc parameters must be included in the challenge response. The cnonce should be 32 octets encoded as ASCII hexadecimal as per [IETF RFC 2617], following the guidelines of [IETF RFC 1750]. The qop value used for the response calculations and returned in the authorization header must be one of the values received in the 401 www-Authenticate header from the S-CSCF. UEs must be able to validate Authentication-Info header values returned from the S-CSCF with the 200 OK message.
+
+UEs must be able to securely store usernames and passwords in a manner that minimizes risk. UEs may optionally prompt users for username and password input.
+
+##### **III.6.1.2.2 S-CSCF**
+
+In order to support new forms of authentication, the S-CSCF must understand new values for the 'algorithm' parameter in the authorization headers sent by UEs. This value must then be used for the 'Authentication-Scheme' AVP in Cx procedures.
+
+In order to support SIP digest, the S-CSCF must be able to calculate digest responses as described in [IETF RFC 3261] and [IETF RFC 2617]. The S-CSCF will receive HA1 from the HSS over the Cx interface, and the S-CSCF must use this HA1 value to create the digest response for this private identity. This response is compared to the response received by the UE, so it must be calculated in the same manner. The qop value received from the UE must be used for the response calculation. If the S-CSCF calculated response is identical to the response received from the UE, the S-CSCF sends a 200 OK containing an Authentication-Info header per [IETF RFC 2617]. The nextnonce parameter must be used in the Authentication-Info header.
+
+Because the security of digest depends greatly on the calculation of the nonce, the S-CSCF must follow these guidelines when regarding nonce creation and use:
+
+- The nonce must be 32 octets encoded as ASCII hexadecimal as per [IETF RFC 2617].
+- The nonce must be generated following pseudo random number generation such as [IETF RFC 1750].
+- Nextnonce is always sent in Authentication-Info responses (e.g., 2xx responses) to successful authentication of the UE.
+
+Based on local policy, the S-CSCF should:
+
+- Accept a previously used nonce with a valid nonce-count, for example, to allow for PRACK and other types of requests received before a 2xx response.
+- Only accept a previously used nonce for a specific period of time. It is recommended to use a time value of 10 minutes or less.
+- Only accept a previously used nonce for a specific number of times. It is recommended to use a value of 5 times or less.
+- Accept an old nonce based on the above policy rules even if nextnonce was sent.
+
+The above policy rules are mainly related to the case where signalling security is disabled in the network.
+
+##### **III.6.1.2.3 HSS**
+
+In order to support new authentication schemes, the Cx interface and procedures must be extended. Digest authentication adds new parameters to the Cx interface, specifically the SIP-Auth-Data-Item AVP present in both MAR and MAA procedures. The authentication vector provides the S-CSCF
+
+with HA1 and other elements to allow the S-CSCF to compute responses. For further details, see Appendix IV.
+
+#### III.6.1.3 Signalling security
+
+The IMS defines IPSec for the secure signalling between UEs and edge proxies. The UICC provides credentials for authentication and IPSec. The security mechanism is negotiated using [IETF RFC 3329] SIP security agreement. However, the only mechanism allowed for negotiation in IMS is ipsec-3gpp.
+
+IPCablecom2 adds TLS as an option for signalling security between the UE and the P-CSCF. The use of TLS by the UE is optional, and is based on the following advantages:
+
+- TLS is the recommended security mechanism specified in [IETF RFC 3261].
+- There is a general shift towards the use of TCP to better handle longer messages.
+- TLS supports NAT traversal at the protocol layer.
+- TLS is implemented at the application level instead of the kernel level, which provides some advantages such as easier support in multiple environments.
+
+Adding support for TLS for signalling leads to the consideration of TLS credentials.
+
+- Mutually authenticated TLS – UE and server both provide certificates when establishing signalling security. The server must validate the UE certificate, and the UE must validate the server certificate. Mutual authentication provides a high degree of security.
+- Server side authentication – Only the server provides a certificate when establishing signalling security. This approach avoids the extra computational overhead of a PKI operation on the UE. Provides a medium level of security, with lower CPU requirements on the UE. May be used to secure HTTP digest sessions.
+
+Both of these models require the P-CSCF and the UE to support PKI features, such as certificate validation and certificate management.
+
+Adding support for TLS also leads to the consideration of TLS port assignments and TLS connection management. IPCablecom2 will use the standard SIP ports for UDP, TCP and TLS. UEs negotiating optional TLS before SIP messaging connect to the SIPS port of 5061. Otherwise, UEs use the standard SIP UDP/TCP port of 5060. Requests and responses are performed according to procedures in [ID SIP-OUTBOUND].
+
+IPCablecom2 supports an optional TLS session prior to SIP signalling, if the UE and P-CSCF support it. This provides security on the initial register message. [IETF RFC 3329] headers are still used during the registration process, to provide security against bid-down attacks and maintain consistency with the existing IMS registration message flow.
+
+Figure III.6 shows signalling security negotiation during a successful register dialogue. Only signalling security headers are shown for simplicity.
+
+![Sequence diagram illustrating Transport security negotiation between UE, P-CSCF, S-CSCF, and HSS. The diagram shows two paths: one for Optional TLS (SSA) and another for the main registration process. The Optional TLS path involves a direct exchange between UE and P-CSCF. The main registration process involves the UE sending a Register to the P-CSCF, which is then forwarded to the S-CSCF and HSS. The S-CSCF and HSS respond with Cx messages. The P-CSCF then sends a 401 Unauthorized to the UE, which responds with a 401 Unauthorized. The P-CSCF then sends a list of supported mechanisms to the UE, which responds with IPSec|TLS. The P-CSCF then sends a Register to the S-CSCF and HSS, which respond with Cx messages. The P-CSCF then sends a 200 OK to the UE, which responds with a 200 OK. The P-CSCF then inserts the P-Asserted-Identity in further messages.](21ea5add6a61cc951b5c43ddffefb3ff_img.jpg)
+
+```
+
+sequenceDiagram
+    participant UE
+    participant P-CSCF
+    participant S-CSCF
+    participant HSS
+
+    Note left of UE: Client sends list of supported security mechanisms
+    UE->>P-CSCF: Optional TLS (SSA)
+    Note right of P-CSCF: Server sends list of supported mechanisms  
+Security-Server: <ipsec-3gpp|tls>
+    P-CSCF->>UE: IPSec|TLS
+    Note left of UE: IPSec or TLS negotiated
+    UE->>P-CSCF: (1) Register
+    Note right of UE: Security-Client=<ipsec-3gpp|tls>  
+Require: sec-agree  
+Proxy-Require: sec-agree
+    P-CSCF->>S-CSCF: (2) Register
+    S-CSCF->>HSS: (3) Cx
+    HSS->>S-CSCF: (4) Cx
+    S-CSCF->>P-CSCF: (5) 401 Unauthorized
+    P-CSCF->>UE: (6) 401 Unauthorized
+    Note right of P-CSCF: Security-Verify=<must be same as Security-Server>  
+Require: sec-agree  
+Proxy-Require: sec-agree
+    UE->>P-CSCF: (7) Register
+    P-CSCF->>S-CSCF: (8) Register
+    S-CSCF->>HSS: (9) Cx
+    HSS->>S-CSCF: (10) Cx
+    S-CSCF->>P-CSCF: (11) 200 OK
+    P-CSCF->>UE: (12) 200 OK
+    Note right of P-CSCF: P-CSCF inserts P-Asserted-Identity in further messages
+  
+```
+
+Sequence diagram illustrating Transport security negotiation between UE, P-CSCF, S-CSCF, and HSS. The diagram shows two paths: one for Optional TLS (SSA) and another for the main registration process. The Optional TLS path involves a direct exchange between UE and P-CSCF. The main registration process involves the UE sending a Register to the P-CSCF, which is then forwarded to the S-CSCF and HSS. The S-CSCF and HSS respond with Cx messages. The P-CSCF then sends a 401 Unauthorized to the UE, which responds with a 401 Unauthorized. The P-CSCF then sends a list of supported mechanisms to the UE, which responds with IPSec|TLS. The P-CSCF then sends a Register to the S-CSCF and HSS, which respond with Cx messages. The P-CSCF then sends a 200 OK to the UE, which responds with a 200 OK. The P-CSCF then inserts the P-Asserted-Identity in further messages.
+
+**Figure III.6 – Transport security**
+
+To support TLS for signalling security between the UE and the P-CSCF, the IMS specifications must be enhanced to allow TLS as an optional SIP security mechanism to be negotiated. [IETF RFC 3329] includes TLS as a security mechanism that can be negotiated, thus the only change is to IMS specifications.
+
+As shown, TLS capable UEs may negotiate server side authenticated TLS before SIP messaging, for instance when a user requires privacy. [IETF RFC 3329] headers are used to negotiate signalling security during the SIP registration, to protect against bid-down attacks, and to maintain consistency with current IMS message flows.
+
+At a high-level, the impacts to IMS components are:
+
+- UE must support the ability to negotiate TLS using [IETF RFC 3329].
+- UE may establish TLS before SIP messaging.
+- P-CSCF must support the ability to negotiate TLS using [IETF RFC 3329].
+- P-CSCF may support TLS before SIP messaging.
+
+##### III.6.1.3.1 Impacted components
+
+The following clauses describe the impacts to IMS components in order to negotiate signalling security.
+
+###### III.6.1.3.1.1 UE
+
+In order to support the negotiation of signalling security, IPCablecom UEs must support TLS as defined in [IETF RFC 2246].
+
+UEs must support the construction and interpretation of [IETF RFC 3329] headers containing the mechanism-name of 'tls'.
+
+###### **III.6.1.3.1.2 P-CSCF**
+
+The P-CSCF must be able to establish TLS sessions based on a request from a UE. The P-CSCF should always request UE certificates, but if it receives none, should establish server side authenticated TLS. If mutually authenticated TLS is established, the P-CSCF must set integrity-protected=yes in Authorization headers. If mutually authenticated TLS is not established, the P-CSCF sets integrity-protected=no. These rules are in addition to the existing rules for IPSec establishment. While server side authenticated TLS provides integrity, mutually authenticated TLS more closely resembles the 3GPP case of IPSec combined with AKA.
+
+The P-CSCF must support the [IETF RFC 3329] mechanism-name of 'tls'. This may be negotiated as either mutual or server side authenticated TLS, depending on the capabilities of the UE. The same rules for assigning integrity-protected values apply as above.
+
+Certificates should be validated according to [IETF RFC 3280].
+
+###### **III.6.1.3.1.3 S-CSCF**
+
+The S-CSCF can challenge any SIP message. Messages containing Authorize headers with integrity-protected set to 'no' should always be challenged, as this flag indicates the lack of signalling security between the UE and the P-CSCF on non-initial register requests. If the S-CSCF successfully challenges a subscriber, the S-CSCF must insert the P-Asserted-Identity header in subsequent messages from that subscriber if the P-Asserted-Identity header does not exist.
+
+##### **III.6.1.3.2 Disabling signalling security**
+
+While not recommended, signalling security may be disabled at the P-CSCF. By disabling signalling security, UEs and the network are exposed to many of the threats described in clause III.5.3, especially when combined with a weaker form of authentication such as SIP digest.
+
+The IPCablecom2 SIP signalling (Appendix I) and the IPCablecom2 [ITU-T J.366.4] delta specification contain detailed information on the procedures for disabling signalling security. The major difference in procedures for disabling signalling security is that non-register dialog requests should now be challenged.
+
+### **III.6.2 Identity assertion**
+
+IP Cablecom environments require a way for trusted network elements to convey the identity of subscribers to other elements or services, and to remove the identity when communicating with untrusted networks. Identity assertion is the mechanism by which elements and services can trust the identity of a user.
+
+As described in [ITU-T J.366.4], IMS assigns the task of identity assertion to P-CSCFs for all SIP messages, based on the strict flow described in clause III.6.1. Once the IPSec security associations (SA) are established and the subscriber is authenticated, the P-CSCF asserts the identity of the subscriber. By monitoring SIP messaging towards the UE, the P-CSCF observes the 200 OK message from the subscribers S-CSCF. This information, plus the presence of SAs to the UE allow the P-CSCF to substantiate successful authentication of the UE.
+
+IP Cablecom2 enhances IMS with the following requirements:
+
+- A P-CSCF with an established TLS session with a UE that observes a 200 OK response from the S-CSCF for that subscriber can assert the identity of the public identity used by that UE.
+- A P-CSCF without an established TLS session that observes a 200 OK response from the UEs S-CSCF during SIP authentication cannot assert the identity of that UE. In this case, the S-CSCF asserts the identity after successful authentication of the subscriber.
+
+### III.6.3 NAT traversal security
+
+The following clauses describe STUN and TURN security.
+
+#### III.6.3.1 STUN
+
+The STUN protocol [IETF RFC 3489] defines the countermeasures for the attacks described in clause III.5.3.2.2. These include network architecture recommendations as well as message integrity mechanisms provided by STUN itself. No additional mechanisms are proposed for this version of this appendix.
+
+#### III.6.3.2 TURN
+
+The TURN server represents a network resource that is utilized for the duration of a connection, therefore security for this resource is an important consideration.
+
+The TURN protocol [ID TURN] defines the countermeasures for the attacks described in clause III.5.3.2.3. These include network architecture recommendations as well as message integrity mechanisms provided by TURN itself. No additional mechanisms are proposed.
+
+NOTE – Security for TURN is being updated. Details will be provided once the TURN draft becomes available.
+
+### III.6.4 Configuration security
+
+#### III.6.4.1 Generic bootstrapping architecture
+
+The 3GPP authentication infrastructure has been recognized for its ability to enable application functions in the network and on the user side to establish shared keys. Therefore, 3GPP designed the "bootstrapping of application security" to authenticate the subscriber by defining a generic bootstrapping architecture (GBA) based on the AKA protocol. GBA reference points and components are shown in Figure III.7.
+
+![Diagram of GBA reference points and components showing HSS, BSF, NAF (AP), and UE with interfaces Zh, Zn, Ub, and Ua.](2d863654cf3803cea82b686d9b3ebee8_img.jpg)
+
+The diagram illustrates the Generic Bootstrapping Architecture (GBA) components and reference points. It consists of four main entities: HSS (Home Subscriber Server), BSF (Bootstrapping Server Function), NAF (AP) (Network Application Function), and UE (User Equipment). The HSS is connected to the BSF via the Zh reference point. The BSF is connected to the NAF (AP) via the Zn reference point. The BSF is also connected to the UE via the Ub reference point. The UE is connected to the NAF (AP) via the Ua reference point. The reference points are indicated by a vertical bar on the connecting lines.
+
+J.360\_FIII.7
+
+Diagram of GBA reference points and components showing HSS, BSF, NAF (AP), and UE with interfaces Zh, Zn, Ub, and Ua.
+
+**Figure III.7 – GBA reference points and components**
+
+IMS currently describes the generic bootstrapping architecture (GBA) based on the AKA protocol. This architecture provides a means for a UE to bootstrap to a server, in order to receive configuration information, and to derive keys that can be used by the UE and application servers to secure communications on the Ua interface.
+
+According to [ITU-T J.366.9], a generic bootstrapping server function (BSF) and the UE shall mutually authenticate using the AKA protocol, and agree on session keys that are afterwards used between the UA and network application function (NAF). For this purpose, the BSF shall acquire the GBA user security settings (GUSS) from the HSS, and shall restrict the applicability of the key material to a specific NAF by using a key derivation procedure. As described in [ITU-T J.366.9], the IMS uses the GBA to authenticate and receive configuration information over IPSec. The IMS requires a UICC-based ISIM for this process, as it relies on IMS AKA for authentication and IPSec for secure transport.
+
+Because IPCablecom2 is extending IMS to support non-UICC deployment scenarios, the AKA protocol cannot be used by all IPCablecom clients to achieve mutual authentication between the UE and the BSF. Consequently, a new procedure is needed. IPCablecom adds an option for the Ub interface to support HTTP Digest over TLS for GBA authentication and key derivation.
+
+Note that in IPCablecom2, the NAF is an XCAP server, which provides the configuration to the UE.
+
+For UEs that do not support IPSec and AKA, when the UE starts communicating with the NAF, it must establish a TLS tunnel with the NAF. The NAF is authenticated to the UE by means of a public key certificate. The UE must verify that the server certificate corresponds to the FQDN of the NAF it established the tunnel with. No UE authentication is performed as part of TLS (i.e., there is no UE certificate necessary). The Zh, Zn and Ua are standard interfaces defined in [ITU-T J.366.9].
+
+The Ub interface uses the HTTP Digest mechanism to establish the credentials (e.g., session key(s)) between the UE and the BSF.
+
+The new bootstrapping exchange on the Ub interface is illustrated in Figure III.8.
+
+![Sequence diagram of GBA message flow between UE, BSF, and HSS. The flow consists of 8 steps: (1) TLS Mutual/SSA handshake between UE and BSF; (2) UE sends a Request to BSF with an Authorization header (private identity, algorithm); (3) BSF sends a Zh request to HSS; (4) HSS returns a 401 Unauthorized response to BSF, which includes a www-authenticate header (nonce, opaque, qop); (5) UE calculates a response and sends a Request to BSF with an Authorization header (private identity, algorithm, response, cnonce, qop, opaque); (6) BSF calculates a response and compares it to the value received from UE; (7) BSF sends a 200 OK response to UE, including B_TID and Ks lifetime; (8) UE and BSF calculate Ks_NAF. A note 'UE calculates response' is shown next to step 5. The diagram is labeled J.360_FIII.8 at the bottom right.](301f4a188198a15b1415d54545b07e0d_img.jpg)
+
+```
+
+sequenceDiagram
+    participant UE
+    participant BSF
+    participant HSS
+    Note left of UE: UE calculates response
+    UE->>BSF: (1) TLS (Mutual/SSA)
+    BSF-->>UE: (1) TLS (Mutual/SSA)
+    UE->>BSF: (2) Request  
+Authorization header: private identity, algorithm
+    BSF->>HSS: (3) Zh
+    HSS-->>BSF: (4) 401 Unauthorized  
+www-authenticate header: nonce, opaque, qop
+    BSF-->>UE: (4) 401 Unauthorized  
+www-authenticate header: nonce, opaque, qop
+    Note left of UE: UE calculates response
+    UE->>BSF: (5) Request  
+Authorization header: private identity, algorithm, response, cnonce, qop, opaque
+    BSF->>HSS: (6) BSF calculates response, compares to value received from UE
+    BSF-->>UE: (7) 200 OK  
+B_TID, Ks lifetime
+    Note left of BSF: (8) UE and BSF calculate Ks_NAF
+  
+```
+
+J.360\_FIII.8
+
+Sequence diagram of GBA message flow between UE, BSF, and HSS. The flow consists of 8 steps: (1) TLS Mutual/SSA handshake between UE and BSF; (2) UE sends a Request to BSF with an Authorization header (private identity, algorithm); (3) BSF sends a Zh request to HSS; (4) HSS returns a 401 Unauthorized response to BSF, which includes a www-authenticate header (nonce, opaque, qop); (5) UE calculates a response and sends a Request to BSF with an Authorization header (private identity, algorithm, response, cnonce, qop, opaque); (6) BSF calculates a response and compares it to the value received from UE; (7) BSF sends a 200 OK response to UE, including B\_TID and Ks lifetime; (8) UE and BSF calculate Ks\_NAF. A note 'UE calculates response' is shown next to step 5. The diagram is labeled J.360\_FIII.8 at the bottom right.
+
+**Figure III.8 – GBA message flow**
+
+The following steps describe the bootstrapping procedure for HTTP Digest over TLS.
+
+- 1) The UE starts the bootstrapping procedure by initiating a TLS session with the BSF. The UE and BSF negotiate server side authenticated TLS. The UE authenticates the BSF by the certificate presented by the BSF. The BSF does not require authentication from the UE at this point.
+- 2) The UE starts the bootstrapping procedure by sending an HTTP Request message to the BSF containing the private identity in an Authorization header. The UE indicates the algorithm it supports in the algorithm parameter of the Authorization header.
+- 3) The BSF sends a MAR command to the HSS to retrieve an authentication vector for that user. The HSS responds with the appropriate authentication vector for that user and algorithm in a MAA message. The authentication vector contents are enhanced as in SIP digest to allow the BSF to calculate a challenge to the UE as described in [IETF RFC 2617].
+
+NOTE 1 – In a multiple HSS environment, the BSF may have to obtain the address of the HSS where the subscription of the user is stored by querying the SLF, prior to step 3.
+
+- 4) The BSF responds to the UE request with a 401 Unauthorized message containing a www-authenticate header to force the UE to authenticate itself. The www-authenticate header includes a nonce, created following the guidelines described earlier in this appendix
+
+(i.e., 32 octets encoded in ASCII hexadecimal). The algorithm parameter informs the UE of the algorithm it should use to calculate its response.
+
+- 5) Upon receiving the challenge, the UE uses the data received in the www-authenticate header to create a second HTTP Request with the challenge response in an Authorization header. The challenge response is calculated per [IETF RFC 2617]. A cnonce must be included. The UE must select a qop value from the list of qop values sent by the BSF. The message is sent to the BSF over the TLS session.
+- 6) The BSF checks the validity of the challenge response sent from the UE by calculating the response on its own and comparing the values. The BSF calculates the response per [IETF RFC 2617]. It uses the HA1 value supplied by the HSS over the Zh reference point.
+- 7) If the challenge response sent by the UE is identical to the response calculated by the BSF, the BSF must send a 200 OK message including the B-TID to the UE to indicate successful authentication. In addition, in a 200 OK message, the BSF shall supply the lifetime of the key Ks.
+
+The B-TID value must be generated in the format of NAI by taking the base64 encoded nonce value from step 4, and the BSF server name, i.e., base64encode(nonce)@BSF\_servers\_domain\_name.
+
+NOTE 2 – Before base64 encoding the nonce from step 4, the nonce must first be converted from a hexadecimal ASCII-encoded value to a binary-encoded value.
+
+- 8) Both the UE and the BSF must use the TLS master secret from the existing TLS session for Ks. Both the UE and the BSF must use the Ks to derive the key material Ks\_NAF. Ks\_NAF must be used for securing the reference point Ua.
+
+Ks\_NAF is computed as  $Ks\_NAF = KDF(Ks, "gba-h", RAND, IMPI, NAF\_Id)$  where KDF is the key derivation function described in Annex B of [ITU-T J.366.9]. The binary-encoded nonce is substituted for the AKA-based RAND variable when calculating Ks\_NAF. Ks is the master secret from the existing TLS session.
+
+The UE and the BSF must store the key Ks with the associated B-TID for further use, until the lifetime of Ks has expired, or until the key is updated.
+
+The key Ks is used to derive keys for communications with application servers, such as the provisioning, activation and configuration (PAC) element, using the Ua reference point.
+
+#### **III.6.4.2 Secure software download**
+
+Secure software download is out-of-scope for this version of this appendix.
+
+### **III.6.5 Media security**
+
+Media security is out-of-scope for this version of this appendix.
+
+### **III.6.6 Using TLS for intra-domain security**
+
+As defined by IMS-delta specification [ITU-T J.366.8], the Zb reference point connects IMS components within the same trust domain in a secure manner. Implementation of the Zb interface is optional. If implemented, the Zb interface must use IPsec ESP for authentication and integrity. Confidentiality (encryption) is optional.
+
+IP Cablecom2 adds TLS support for intra-domain security, for the following reasons:
+
+- TLS is the recommended security mechanism specified in [IETF RFC 3261].
+- TLS supports NAT traversal at the protocol layer.
+- TLS is implemented at the application level instead of the kernel level, which provides some advantages such as easier support in multiple environments.
+
+IPCablecom2 components with SIP interfaces are required to support TLS for intra-domain security, in addition to IMS defined IPSec.
+
+Unless specified within this clause, SIP interfaces requiring TLS MUST be compliant with the TLS specification [IETF RFC 2246] and any requirements specified in [IETF RFC 3261] relating to its usage in SIP.
+
+TLS [IETF RFC 2246] supports the negotiation and use of compression methods. However, since these methods are not specified within TLS [IETF RFC 2246], compression MUST NOT be used.
+
+#### **III.6.6.1 TLS authentication algorithms**
+
+The HMAC-SHA-1 (with 160-bit key) algorithm must be supported in order to provide data origin authentication and data integrity services in TLS. AES-XCBC is not required.
+
+#### **III.6.6.2 Key exchange algorithms for TLS**
+
+The following are the requirements relating to methods for key exchange within the TLS protocol:
+
+- Rivest Shamir Adleman (RSA) must be supported.
+- Diffie Hellman (DH) must be supported.
+
+#### **III.6.6.3 Use of X.509 certificates in TLS**
+
+X.509 certificates are used for authentication in TLS, and all X.509 certificates should be signed by a trusted party. Self-signed certificates may be used.
+
+#### **III.6.6.4 Random number generator for TLS**
+
+Random number generation implementations tend to be a weak. Many semiconductor manufacturers are adding secure random number generators to their integrated circuits, which should be used if available. If no hardware is available, strong pseudo-random number generator software may optionally be used in keeping with [IETF RFC 1750].
+
+The following are the requirements relating to random number generation:
+
+- A hardware random number generator may be supported.
+- Pseudo random number generator software must be supported if a hardware random number generator is not supported.
+
+#### **III.6.6.5 TLS encryption algorithms**
+
+The following are the TLS client and TLS server requirements related to cryptographic algorithms for providing encryption services for TLS-SA:
+
+- 3DES CBC-mode (with 3 independent 56-bit keys) must be supported.
+- AES CBC (with 128-bit key) must be supported.
+- Null encryption may be supported.
+
+#### **III.6.6.6 Ciphersuites for TLS**
+
+TLS specifies various ciphersuites for use within the TLS protocol, as discussed in detail in [IETF RFC 3268]. Ciphersuites represent the recommended combinations of encryption authentication and key exchange algorithms to be used within the TLS.
+
+The following are the requirements related to Ciphersuites.
+
+- "TLS\_RSA\_WITH\_NULL\_SHA" may be supported.
+- "TLS\_RSA\_WITH\_3DES\_EDE\_CBC\_SHA" should be supported.
+- "TLS\_RSA\_WITH\_AES\_128\_CBC\_SHA" must be supported
+- "TLS\_DH\_RSA\_WITH\_3DES\_EDE\_CBC\_SHA" should be supported.
+
+- "TLS\_DH\_RSA\_WITH\_AES\_128\_CBC\_SHA" must be supported.
+
+#### **III.6.6.7 TLS authentication**
+
+TLS allows either unidirectional authentication where the server is authenticated to the client only, or bidirectional authentication where both client and server authenticate to each other. Unidirectional authentication is the usual method used in the public Internet; however, for network signalling and control applications, bidirectional authentication is mandatory to allow both parties to know they are communicating with the desired endpoint.
+
+The following are the requirements related to TLS authentication.
+
+- Bidirectional authentication for TLS applications must be supported.
+
+### **III.6.7 Certificate validation**
+
+[IETF RFC 3280] should be used for guidance on validation of certificates.
+
+### **III.6.8 Certificate revocation**
+
+Certificate revocation is out of scope for this version of this appendix.
+
+# Appendix IV
+
+# IPCablecom2 home subscriber server (HSS) overview
+
+(This appendix does not form an integral part of this Recommendation)
+
+*For further study.*
+
+# Appendix V
+
+# IPCablecom2 NAT and firewall traversal overview
+
+(This appendix does not form an integral part of this Recommendation)
+
+## V.1 Introduction
+
+This appendix provides an overview of how the IPCablecom2 architecture and associated UEs support the traversal of NA(P)T and firewall devices (commonly referred to as NAT) for media and signalling flows as well as for provisioning and management. To aid the reader in understanding the IPCablecom2 NAT traversal approach and methodologies, the high level goals and specific logical components and interfaces defined are discussed in this appendix.
+
+## V.2 References
+
+This appendix uses the following additional informative references.
+
+- [ITU-T J.179] ITU-T Recommendation J.179 (2005), *IPCablecom support for multimedia*.
+- [ITU-T J.364] ITU-T Recommendation J.364 (2006), *IPCablecom2 provisioning, activation, configuration and management*.
+- [IETF RFC 2663] IETF RFC 2663 (1999), *IP Network Address Translator (NAT) terminology and considerations*.
+- [ID BEHAVE] IETF draft, draft-ietf-behave-nat-udp-04, *Network Address Translation (NAT) Behavioural Requirements for Unicast UDP*, 6 September 2005.
+- [ID ICE] IETF draft, draft-ietf-mmusic-ice-07, *Interactive Connectivity Establishment (ICE): A Methodology for Network Address Translator (NAT) Traversal for Offer/Answer Protocols*, 6 March 2006.
+- [ID OUTBOUND] IETF draft, draft-ietf-sip-outbound-03, *Managing Client Initiated Connections in the Session Initiation Protocol (SIP)*, 20 March 2006.
+- [IETF RFC 3489] IETF RFC 3489 (2003), *Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NAT) (STUN)*.
+- [ID TURN] IETF draft, draft-ietf-behave-turn-00, *Obtaining Relay Addresses from Simple Traversal of UDP Through NAT (STUN)*, February 2005.
+
+## V.3 Terms and definitions
+
+Various terms related to NAT are defined in [IETF RFC 2663]; please refer to it for the general NAT terms and definitions not present below. In addition, this appendix uses the following terms:
+
+**V.3.1 ALG:** An Application layer gateway within a NAT device which attempts to sniff application signalling and modify application addresses appropriately in order to take care of changes caused by the NAT.
+
+**V.3.2 NAT; NAPT:** NATs perform IP address translation, typically interconnecting private and public address domains. NAPT devices also translate ports in order to save IP addresses. In this appendix, the term NAT also refers to NAPT devices.
+
+## **V.4 Abbreviations and acronyms**
+
+This appendix uses the following additional abbreviations:
+
+DQoS            Dynamic Quality of Service
+
+UDPTL          UDP Transport Layer
+
+VPN              Virtual Private Network
+
+## **V.5 IPCablecom2 NAT requirements and scope**
+
+The objective of this appendix is to provide an architecture definition for a UE to obtain access to the IPCablecom2 network in the presence of one or more NAT device(s). In particular, it outlines a comprehensive set of mechanisms for a UE to maintain both signalling and media bindings to ensure both media and signalling traffic destined for the UE is able to traverse the NAT as well as to allow the UE to be provisioned and managed when located behind a NAT.
+
+In addition, this architecture provides support for failover of signalling paths through a backup Proxy-CSCF (P-CSCF).
+
+Finally, this architecture recognizes that UEs will have to interwork with non-IP Cablecom2 devices that do not support the required NAT traversal mechanisms and provide for these cases.
+
+The following clause captures the set of architecture requirements necessary to achieve the objective.
+
+### **V.5.1 Requirements**
+
+The following list contains requirements that a general-purpose NAT traversal solution should satisfy to support the services envisioned for IPCablecom2:
+
+- Support multiple UEs (on one or more devices) behind a single NAT.
+- No requirements will be imposed on the NAT devices, nor require the network to be aware of the presence of a NAT.
+- Support both inbound and outbound requests to and from UEs through one or more NAT device(s).
+- Maintain bindings to multiple P-CSCFs to provide reliable inbound message delivery in the face of a P-CSCF failure.
+- Support the traversal of NATs between the UE and network (home NAT, visited network NAT).
+- Be Application independent: the solution should not employ application-specific mechanisms which could not be used by other non-SIP based solutions. The solutions, actually used, may require application support.
+- Avoid unnecessarily long media paths due to media pinning.
+- Re-establish communications in failure situations (e.g., the NAT device re-boots and NAT bindings are lost).
+
+### **V.5.2 Scope**
+
+The scope of the IPCablecom2 NAT traversal solution is limited to NATs within the access network. In the case of cable access, this implies NATs that are between the UE and CMTS. Note that IPCablecom E-MTAs are out of scope for this appendix. However, some additional requirements may be placed on IPCablecom E-MTAs in order to ensure they interoperate with
+
+IPCablecom2 UEs following the traversal procedures described in this appendix and other specifications.
+
+### V.5.3 Limitations
+
+This appendix does not address NAT and firewall traversal of ITU-T T.38 fax media streams over user datagram protocol transport layer (UDPTL).
+
+Operator call-back for emergency calls (such as 911) made without first registering is not currently supported.
+
+## V.6 NAT background
+
+Network address translators (NATs) translate addresses between one IP address realm and another. This mapping is most commonly done between a private Internet address space using addresses set aside for that purpose and a public Internet address space. This mapping is commonly referred to as a NAT binding as the NAT has bound together the tuple of PrivateIP:PrivatePort to PublicIP:PublicPort to allow the subsequent response packets from the external endpoint to be forwarded to the proper internal host. The term NAT in this appendix also refers to network address port translation (NAPT) devices which also translate port addresses in order to reduce the number of public addresses used on the public address side of the NAT (see [IETF RFC 2663] section 4 for more details).
+
+In addition to address translation, NAT devices also exhibit firewall characteristics. In other words, they block traffic coming across the NAT (from outside to inside the NAT/FW device) based on certain filtering rules.
+
+### V.6.1 Types of NA(P)T and firewall devices
+
+The following subclauses use the definitions from the IETF BEHAVE working group as defined in [ID BEHAVE].
+
+#### V.6.1.1 Types of NATs
+
+The definitions from [ID BEHAVE] are included here for convenience:
+
+**Endpoint independent mapping:** The NAT reuses the port mapping for subsequent packets sent from the same internal IP address and port to any external IP address and port.
+
+**Address dependent mapping:** The NAT reuses the port mapping for subsequent packets sent from the same internal IP address and port to the same external IP address, regardless of the external port. If the packets are sent to a different external IP address, the mapping will be different.
+
+**Address and port dependent mapping:** The NAT reuses the port mapping for subsequent packets sent from the same internal IP address and port to the same external address and port. If packets are sent to a different IP address and/or port, then a different mapping will be used.
+
+This address mapping behaviour is described in Table V.1 by making use of the illustration in Figure V.1.
+
+![Diagram illustrating NAT address mapping. A central NAT box is divided into 'Internal' and 'External' sides by a dashed vertical line. On the internal side, an endpoint 'X' with address 'X:x' is connected. On the external side, two endpoints, 'Y1' and 'Y2', are shown. Endpoint 'Y1' has address 'Y1:y1' and is connected to the NAT's external address 'X1:x1'. Endpoint 'Y2' has address 'Y2:y2' and is connected to the NAT's external address 'X2:x2'. The diagram shows how the same internal address 'X:x' is translated to different external addresses ('X1:x1' and 'X2:x2') depending on the destination endpoint.](f2a6c46fa05d5588ce4c6e1a3ee194c7_img.jpg)
+
+Diagram illustrating NAT address mapping. A central NAT box is divided into 'Internal' and 'External' sides by a dashed vertical line. On the internal side, an endpoint 'X' with address 'X:x' is connected. On the external side, two endpoints, 'Y1' and 'Y2', are shown. Endpoint 'Y1' has address 'Y1:y1' and is connected to the NAT's external address 'X1:x1'. Endpoint 'Y2' has address 'Y2:y2' and is connected to the NAT's external address 'X2:x2'. The diagram shows how the same internal address 'X:x' is translated to different external addresses ('X1:x1' and 'X2:x2') depending on the destination endpoint.
+
+**Figure V.1 – Types of NATs (Address mapping)**
+
+In Figure V.1, address  $X:x$  inside the NAT is translated to address  $X1:x1$  when communicating with  $Y1:y1$  outside the NAT. The same address  $X:x$  translates to  $X2:x2$  when communicating with  $Y2:y2$ .
+
+**Table V.1 – Types of NATs (Address mapping)**
+
+| Type of NAT                        | Mapping description                                     |
+|------------------------------------|---------------------------------------------------------|
+| Endpoint independent mapping       | $X1:x1$ always equals $X2:x2$ for all values of $Y2:y2$ |
+| Address dependent mapping          | $X1:x1$ equals $X2:x2$ only if $Y1$ equals $Y2$         |
+| Address and port dependent mapping | $X1:x1$ equals $X2:x2$ only if $Y1:y1$ equals $Y2:y2$   |
+
+Note that for small NATs (e.g., residential CPE NATs), a single IP address (usually from the public space) is normally assigned as the external IP address (i.e.,  $X1 = X2$ ). However, larger NATs will assign the external IP address from a pool of available IP addresses.
+
+#### V.6.1.2 Filtering behaviour
+
+Filtering behaviour in [ID BEHAVE] is described in terms of similar categories:
+
+- Endpoint independent filtering: sending packets from the internal side of the NAT to any external IP address is sufficient to allow any packets back to the internal endpoint.
+- Address dependent filtering: in order to receive packets from a specific external endpoint, it is necessary for the internal endpoint to send packets first to that specific external endpoint's IP address.
+- Address and port dependent filtering: receiving packets from a specific external endpoint, it is necessary for the internal endpoint to send packets first to that external endpoint's IP address and port.
+
+Table V.2 describes this filtering behaviour which can be described in terms of the examples shown in Figure V.1.
+
+**Table V.2 – Types of filtering behaviour**
+
+| Type of NAT                          | Filtering example                                                                                                                                               |
+|--------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Endpoint independent filtering       | Packets sent from X:x to Y1:y1 will enable packets from Y1:y1 or Y2:y2 to be received.                                                                          |
+| Address dependent filtering          | Packets sent from X:x to Y1:y1 will enable packets to be received from Y1:z for any port z but will not allow packets to be received from any other IP address. |
+| Address and port dependent filtering | Packets sent from X:x to Y1:y1 will only allow packets to be sent from Y1:y1 to X:x.                                                                            |
+
+### V.6.2 NA(P)T and firewall traversal considerations
+
+While NAT devices provide a rather simple solution to IP address exhaustion, the consequence is that these devices break many existing applications; in particular, applications and real-time communication protocols such as SIP, which depend on the exchange of addressing information within the protocol itself (sometimes in SIP header lines, or more generally, inside the SDP message body of some SIP messages). If the address within the protocol is unreachable, the recipient of the message will be unable to successfully respond resulting in failed sessions. Given the growing problem NAT devices present to communications protocols, several solutions have been used in the past and proposed for the future. The following list provides a snapshot of some of the more prevalent approaches and their drawbacks:
+
+- Application layer gateway (ALG): One solution is for the NAT device to contain an Application layer gateway which looks inside the protocol messages and modifies them based on the NAT bindings it has created. However, this requires constant update of the ALG as protocols evolve so that the expected operation is preserved. In addition, this approach fails when the protocol includes an integrity check or is encrypted.
+- Another approach is that proposed by the IETF MIDCOM group. In this approach, a signalling element directly controls the NAT device to open firewall pinholes for the media and to obtain the NAT binding information needed to update any IP addressing information (e.g., SDP) within the protocol. However, this requires NAT device support and requires that the signalling device is somehow able to determine which NAT device to control.
+- Other proposed solutions include directly inserting a media relay (an additional address translator) in the path or tunneling through the NAT device using VPN technology. Each of these methods has its pros and cons but the major disadvantage is that it forces the media along the same path as the signalling. This may not result in the most optimum media routing in certain circumstances.
+- The present short-term solution defined within the IETF is to make use of the ICE methodology [ID ICE], with STUN [IETF RFC 3489] and TURN [ID TURN] for media and outbound [ID OUTBOUND] for signalling. ICE allows an endpoint to discover, advertise and find the best address for communicating using the mechanisms described [ID ICE] while outbound allows the endpoint to actively manage its connectivity to the SIP network by creating and maintaining flows to its provisioned proxy(s) as described in the outbound [ID OUTBOUND].
+- Other solutions are being examined within the IETF BEHAVE working group. However, this involves longer-term modification of NAT behaviour in order to solve these problems.
+
+In addition to the problem of protocols which embed IP address information within their payload, NAT devices cause other problems such as:
+
+- NAT devices have timeouts associated with NAT bindings and firewall pinholes. For UDP based transports, these bindings tend to have rather short lifetimes; and if traffic is absent for a period of time, the bindings become invalid and pinholes close. To avoid this situation, mechanisms must be in place to maintain the bindings/pinholes for both media and signalling.
+- The IETF RTP protocol specifies that, for UDP and similar protocols, RTP should use an even destination port number and the corresponding RTCP stream should use the next higher (odd) destination port number. However, NAT translations will make this practice invalid since they typically do not maintain these port relationships across the NAT.
+- Another issue of concern is the routing of inbound signalling to UE devices. This signalling must be routed through the NAT over a connection for which there is an existing NAT binding.
+
+Given the requirements provided in clause V.5.1, the current IETF solution using ICE (for media) and OUTBOUND (for signalling) was chosen for IPCablecom2. Not only do these solutions satisfy the stated requirements, but they have the benefit of growing industry support.
+
+## V.7 IPCablecom2 NAT architecture
+
+Figure V.2 is a reference diagram showing key components and interfaces related to NAT/FW traversal in the IPCablecom2 architecture. The cable modem is not shown since it does not contain any functions specifically related to or impacted by NAT traversal.
+
+![Figure V.2 – NAT and FW traversal reference points. A block diagram showing the network architecture for NAT/FW traversal. On the left, a UE (User Equipment) is connected to a NAT & FW (Network Address Translation & Firewall) device. The UE has two interfaces: A1:a1 and A2:a2. The NAT & FW device has three interfaces: X1:x1, X2:x2, and X3:x3. The X1:x1 interface is connected to a Gm interface, which leads to a box containing a STUN server and a P-CSCF. The P-CSCF is connected via an Mw interface to an S-CSCF. The X2:x2 interface is connected to a CMTS (Cable Modem Termination System) via a path labeled pkt-nat-1. The CMTS is connected to a TURN server via a Z1:z1 interface. The TURN server has an output Z2:z2. The X3:x3 interface is connected to another STUN server via a path labeled pkt-nat-2. Between the P-CSCF and the CMTS, there is a vertical stack of components: an IPCablecom application manager, a Policy server, and a CM (Cable Modem). The label J.360_FV.2 is in the bottom right corner.](0bbbad069459da54c1cdef84c90b316a_img.jpg)
+
+Figure V.2 – NAT and FW traversal reference points. A block diagram showing the network architecture for NAT/FW traversal. On the left, a UE (User Equipment) is connected to a NAT & FW (Network Address Translation & Firewall) device. The UE has two interfaces: A1:a1 and A2:a2. The NAT & FW device has three interfaces: X1:x1, X2:x2, and X3:x3. The X1:x1 interface is connected to a Gm interface, which leads to a box containing a STUN server and a P-CSCF. The P-CSCF is connected via an Mw interface to an S-CSCF. The X2:x2 interface is connected to a CMTS (Cable Modem Termination System) via a path labeled pkt-nat-1. The CMTS is connected to a TURN server via a Z1:z1 interface. The TURN server has an output Z2:z2. The X3:x3 interface is connected to another STUN server via a path labeled pkt-nat-2. Between the P-CSCF and the CMTS, there is a vertical stack of components: an IPCablecom application manager, a Policy server, and a CM (Cable Modem). The label J.360\_FV.2 is in the bottom right corner.
+
+**Figure V.2 – NAT and FW traversal reference points**
+
+The network addresses shown in the Figure V.2 are of the form "IP\_address:port". Note that:
+
+- For UE devices, the same IP address is normally used for media and signalling: A1 = A2.
+- For residential CPE NAT/FW devices (e.g., deployed in residential environment), normally X1=X2=X3. For larger NATs, with large numbers of client devices, the external IP address may be selected from a pool of IP addresses.
+
+It is understood that there are other network topologies with NAT devices that may be encountered, such as a network NAT. These other networks are currently outside the scope of IPCablecom2 and thus are not addressed within this appendix. Some network topologies (such as points of interconnection) may be deemed in scope and covered in other documents.
+
+**Table V.3 – IPCablecom2 NAT reference points**
+
+| Reference points | IPCablecom2 network elements | Reference point description                                                                                                                                                                         |
+|------------------|------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Gm               | UE – P-CSCF                  | Allows the UE to communicate with the P-CSCF for registration and session control. This reference point is SIP-based and is defined in [ITU-T J.366.4]                                              |
+| Mw               | CSCF – CSCF                  | Allows the communication and forwarding of signalling messaging among CSCFs in support of registration and session control. This reference point is SIP-based and is defined in [ITU-T J.366.4]     |
+| pkt-nat-1        | UE – STUN server/P-CSCF      | A STUN-based interface defined by [IETF RFC 3489] and used by the UE to determine the IP address assigned to its serving NAT or to keep NAT bindings active to a P-CSCF via a keep-alive mechanism. |
+| pkt-nat-2        | UE – TURN server             | A TURN-based interface defined by [ID TURN] and used by the UE to request TURN server resources for relaying media packets to/from the requesting UE.                                               |
+
+### V.7.1 Relationship to IPCablecom multimedia
+
+Functional elements from the IPCablecom multimedia architecture [ITU-T J.179] are also shown in Figure V.2. This includes the application manager (AM) as well as the policy server (PS). Although this appendix does not impact IPCablecom multimedia operation, there is a requirement for the AM to supply appropriate packet classifier definitions for media flows to the CMTS.
+
+The AM builds packet classifiers for media flows using the default IP address and port as advertised in the "m=" and "c=" lines of the SDP. When a UE invokes the ICE procedure and gathers candidate addresses, it is required to use the TURN server assigned address and port as the default address in the SDP.
+
+When a TURN server is used, the default address advertised in the SDP as illustrated in Figure V.2 is "Z2:z2". However, this is of no value in defining a packet classifier, so some unique filter must be available in the SDP for describing the flows from addresses "X2:x2" and "Z1:z1". Since the client knows where to send the packets, it knows the value of "Z1:z1" and will need to supply this via SDP (a new SDP attribute defined in [ITU-T J.366.4]).
+
+### V.7.2 Relationship to 3GPP IMS Release 6
+
+IPCablecom2 is based on Release 6 of the IP multimedia subsystem (IMS) as defined by the 3rd generation partnership project (3GPP). 3GPP is a collaboration agreement between various standards bodies. The scope of 3GPP is to produce Technical Specifications and Technical Reports for GSM and 3rd generation (3G) mobile system networks.
+
+The current IMS Release 6 architecture does not provide support for NAT and firewall traversal. Given this limitation and the requirement for IPCablecom2 to support the traversal of NAT and firewall devices, IPCablecom2 has added the necessary requirements to the existing IMS Release 6 documents. The changes to IMS are confined to two Technical Specifications, ITU-T Rec. J.366.3 and [ITU-T J.366.4].
+
+The changes to ITU-T Rec. J.366.3 add requirements for supporting NAT and firewall traversal from the architecture perspective.
+
+The changes to [ITU-T J.366.4] document procedures related to both signalling and media traversal of NAT and firewall devices. These changes involve adding support for the IETF [ID OUTBOUND] for signalling and the IETF Interactive Connectivity Establishment [ID ICE] for media. Clause V.8 provides a high-level overview of the associated interfaces and network element roles as they relate to NAT traversal.
+
+### **V.7.3 Relationship to IPCablecom E-MTAs**
+
+This appendix does not apply to IPCablecom E-MTAs. However, the proposed solution does imply a requirement on IPCablecom E-MTAs to be able to accept an empty (no payload) RTP packet with a payload type of 20 as a keep-alive for maintaining NAT bindings for media.
+
+### **V.7.4 Provisioning and management**
+
+In addition to supporting the traversal of NAT devices for signalling and media, it is also imperative that the UE be able to be provisioned and managed when behind a NAT. Provisioning refers to the processes involved in the initialization of user attributes and resources on user equipment and network components to provide services to a user. Management refers to the protocols, methodologies, and interfaces that enable monitoring, regulating, and ensuring availability of offered services in a service provider network.
+
+#### **V.7.4.1 Provisioning**
+
+The IPCablecom2 provisioning process relies on standard SIP signalling, in particular the SUBSCRIBE/NOTIFY methods. The unique aspect of the provisioning process is that it happens prior to UE registration, which is when NAT bindings are typically created. Given this pre-registration procedure, the P-CSCF needs to leverage IETF Outbound concepts to ensure it can deliver the response to the Subscribe request and the subsequent Notification. This is most easily accomplished by requiring the P-CSCF to add a record route header and insert a flow token in the user portion of the URI used in the record route header field value. The flow token acts as an identifier for the flow over which the SUBSCRIBE was received. The flow allows the P-CSCF to identify the source IP address and port contained in the IP header of the SUBSCRIBE request.
+
+In addition, the UE needs to ensure that the NAT bindings remain active on the life of the subscription so that the associated NOTIFY can be delivered.
+
+#### **V.7.4.2 Management**
+
+UE management is currently out of scope and thus no procedures on how to manage a UE behind a NAT have been developed.
+
+## **V.8 Architecture description**
+
+Clause V.7 described a set of logical network entities grouped by specific service functions (NAT), as well as a set of interfaces that support the information flows exchanged between the functional groups and network entities. This clause provides a more detailed discussion of those logical elements and the associated interfaces to the IPCablecom2 architecture. It also provides an overview of other topics related to the NAT architecture that are not documented elsewhere.
+
+### **V.8.1 Functional components**
+
+In this clause, additional detail is provided on each of the functional elements in the IPCablecom2 architecture and their role in NAT and firewall traversal.
+
+#### **V.8.1.1 P-CSCF**
+
+The P-CSCF's primary role in NAT traversal is to ensure that requests and responses occur across a flow for which there is an existing NAT binding. When a registration occurs, the P-CSCF stores a flow identifier token in the SIP path header, so that for incoming requests that contain a URI with that flow identifier token, it can identify which flow to use.
+
+The P-CSCF also supports the rport extension to ensure that all responses to the UE including those from mid-dialog requests are sent to the same source IP address and port over which the request was received to ensure their ability to traverse the NAT.
+
+The P-CSCF also acts as a STUN server to allow the UE to use STUN for keep-alives and to check for changes in NAT bindings (e.g., to check for NAT re-boots that would result in removal of the flow).
+
+#### **V.8.1.2 S-CSCF/Registrar**
+
+The S-CSCF/Registrar is responsible for generating and assigning the globally routable user agent uniform resource identifier (GRUU) for the UE as well as the associated P-CSCF. The S-CSCF/Registrar stores the instance-id associated with the GRUU as well as the reg-id and path header and includes these as part of the contact information.
+
+#### **V.8.1.3 UE**
+
+The UE is responsible for managing the overall NAT discovery process and for invoking the various protocol mechanisms to implement the NAT traversal approach. Depending on the UE type (stand-alone, embedded, etc.), the following protocols or mechanisms are necessary:
+
+- Outbound for signalling.
+- STUN client and server for maintaining NAT bindings (signalling and media), connectivity checks (ICE) and candidate address gathering (ICE).
+- TURN client for media relay.
+- ICE methodology for media.
+
+Before the UE can receive inbound session requests (or responses to outbound session requests), it will need to invoke the procedures defined in [ID OUTBOUND] during the registration process to create a flow to its assigned P-CSCF. Once flows have been created, the UE can then initiate sessions and receive session requests through the NAT.
+
+During the session establishment process, the UE initiates the ICE methodology to gather, advertise and test candidate addresses.
+
+The UE also makes use of the rport extension parameter of the Via header as defined in IETF RFC 3581 for symmetric response routing of SIP messages.
+
+#### **V.8.1.4 STUN servers**
+
+STUN servers receive STUN binding requests and provide a response containing the source IP address and port contained in the IP header of the STUN binding request. Two STUN servers are shown in Figure V.2:
+
+- The STUN server shown as a functional component within the P-CSCF is used by the UE in order to maintain the NAT bindings for signalling. These STUN messages may also act as a keep-alive, allowing the UE to determine P-CSCF availability.
+
+- The external STUN server in the lower right hand corner of Figure V.2 is used as part of the ICE methodology [ID ICE] to determine one of several possible candidate media addresses using STUN [IETF RFC 3489]. For the example media stream shown with source IP address "A2:a2", the UE obtains translated address "X3:x3" via the STUN server.
+
+#### V.8.1.5 TURN server
+
+In addition to the STUN servers, the architecture also contains a TURN server. This may be required if the NAT device does not use endpoint independent mapping (see clause V.6.1.1). When used to transfer media, the TURN server acts as a media relay. The UE sends packets from address "A2:a2" to the TURN server address "Z1:z1". The source address of these packets is first translated by the NAT to "X2:x2" and then relayed by the TURN server so that the source address becomes "Z2:z2". The TURN server also relays media packets in the opposite direction, i.e., packets sent to "Z2:z2" will be sent to "X2:x2" and then via the NAT to "A1:a2". Note that the TURN server provides address independent filtering (see clause V.6.1.2), this retaining some of the filtering characteristics of a NAT, but does not maintain port restrictions, i.e., if traffic is sent to an IP address, it is allowed from that address regardless of what port from which it comes.
+
+Note that only a single example media stream is illustrated in Figure V.2. In fact there may be multiple media streams and each media stream may have an RTP stream as well as an RTCP control channel using RTCP. NAT translations and the corresponding mechanisms for communicating are relevant to both.
+
+### V.8.2 Protocol interfaces and reference points
+
+This appendix has identified several interfaces, or reference points, in the IPCablecom2 NAT traversal architecture. An overview of the various protocol interfaces is provided within this clause.
+
+#### V.8.2.1 NAT traversal for media
+
+UEs communicate via a network that provides signalling components as well as STUN and TURN servers to enable NAT traversal. UE support includes the STUN and TURN protocols as well as the ICE methodology. The associated requirements are provided in the following subclauses. The diagram in Figure V.3 illustrates an abstract view of the architecture.
+
+![Figure V.3 – Abstract reference diagram. The diagram shows two User Equipment (UE) blocks on the left and right, connected to a central 'Network' cloud. Each UE block contains three stacked components: 'STUN', 'TURN client', and 'ICE support'. The 'Network' cloud contains two circular components: 'Signalling components' (top) and 'STUN and TURN servers' (bottom). Arrows labeled 'Signalling' point from the UE blocks to the 'Signalling components' circle. Arrows labeled 'Media' point from the 'ICE support' components in the UE blocks to the 'STUN and TURN servers' circle. A small label 'J.360_FV.3' is in the bottom right corner of the diagram area.](fae02fa1dac97fc5f19a7b85d20df290_img.jpg)
+
+Figure V.3 – Abstract reference diagram. The diagram shows two User Equipment (UE) blocks on the left and right, connected to a central 'Network' cloud. Each UE block contains three stacked components: 'STUN', 'TURN client', and 'ICE support'. The 'Network' cloud contains two circular components: 'Signalling components' (top) and 'STUN and TURN servers' (bottom). Arrows labeled 'Signalling' point from the UE blocks to the 'Signalling components' circle. Arrows labeled 'Media' point from the 'ICE support' components in the UE blocks to the 'STUN and TURN servers' circle. A small label 'J.360\_FV.3' is in the bottom right corner of the diagram area.
+
+**Figure V.3 – Abstract reference diagram**
+
+##### V.8.2.1.1 ICE
+
+The ICE methodology [ID ICE] consists of the following steps:
+
+- Gathering candidate addresses for media communications.
+- Advertising the candidate addresses along with the active transport address in the m/c lines of the SDP.
+
+- Doing connectivity checks on the candidate addresses in order to select a suitable address for communications.
+- Depending on the results of the connectivity checks, one of the candidate addresses may be promoted to become the active transport address.
+- Maintaining the bindings for media.
+
+If one of the endpoints does not support ICE, that endpoint will ignore any of the "a=candidate" attributes and will not provide any of these attributes. In that case, the default value in the m/c lines will be used and connectivity checks will not be done.
+
+##### **V.8.2.1.2 PKT-NAT-1**
+
+Simple traversal of UDP through NAT (STUN) provides a toolkit of functions. These functions allow entities behind a NAT to learn the address bindings allocated by the NAT, to keep those bindings open, and communicate with other STUN-aware devices to validate connectivity. STUN requires no changes to NATs, and works with an arbitrary number of NATs in tandem between the application entity and the public Internet.
+
+STUN is a simple client-server protocol. A client sends a request to a server, and the server returns a response. There are two types of requests – Binding Requests, sent over UDP, and Shared Secret Requests, sent over TLS over TCP. Shared Secret Requests ask the server to return a temporary username and password. This username and password are used in a subsequent Binding Request and Binding Response, for the purposes of authentication and message integrity.
+
+Binding requests are used to determine the bindings allocated by NATs. The client sends a Binding Request to the server, over UDP. The server examines the source IP address and port of the request, and copies them into a response that is sent back to the client.
+
+Once the client learns the WAN address of its local NAT, it will advertise this learned address as a candidate address in the SDP for remote endpoints to try and reach through the ICE process.
+
+##### **V.8.2.1.3 PKT-NAT-2**
+
+TURN is useful for applications that require a client to place a transport address into a protocol message, with the expectation that the client will be able to receive packets from a single host that will send to this address. Examples of such protocols include SIP, which makes use of the session description protocol (SDP). SDP carries an IP address on which the client will receive media packets from its peer. TURN is a simple client-server protocol. It is identical in syntax and general operation to STUN, in order to facilitate a joint implementation of both. TURN defines a request message, called Allocate, which asks the TURN server to allocate a public IP address and port. TURN can run over UDP and TCP, as it allows for a client to request address/port pairs for receiving both UDP and TCP.
+
+A TURN client first discovers the address of a TURN server based on configuration (see [ITU-T J.364]). This can be preconfigured as an IP address, domain name, or FQDN. This will allow for different TURN servers for UDP and TCP. Once a TURN server is discovered, the client sends a TURN Allocate request to the TURN server. TURN provides a mechanism for mutual authentication and integrity checks for both requests and responses, based on a shared secret. Assuming the request is authenticated and has not been tampered with, the TURN server allocates a transport address to the TURN client, called the allocated transport address, and returns it in the response to the Allocate Request. Normally, the allocated transport address will be on one of the interfaces on the TURN server itself. However, it is also allowed for the TURN server to be behind a NAT, in which case the allocated transport address may correspond to the NAT, which is then mapped to the private address of the TURN server. Proper operation of the TURN server will require it to have many bindings established in the NAT ahead of time; the means for doing so are outside the scope of this appendix.
+
+Once the client is assigned a TURN address, it will advertise this address in the "c=" line of the SDP. As a result the TURN server will be the first used address until the other candidate address is found to be a better path through the ICE process.
+
+#### V.8.2.2 Gm (NAT traversal for signalling)
+
+This clause provides a high-level overview of the procedures defined in [ID OUTBOUND] and roles of the various IPCablecom2 network elements. Note that the term flow is used in [ID OUTBOUND] and in the following clauses to describe a network layer connection that uses the same IP addresses and ports (UDP or TCP) at either end of the connection.
+
+![Diagram illustrating NAT traversal for SIP signalling. A User Equipment (UE) connects to a NAT & FW box. From the NAT & FW box, multiple paths lead to different P-CSCF boxes, each containing a STUN server. All P-CSCF boxes then connect to a central S-CSCF/Registrar box. SIP signalling is shown entering the NAT & FW box from the UE.](c21bad844b5cb6026c067a1f43ce67c3_img.jpg)
+
+```
+
+graph LR
+    UE[UE] -- "SIP signalling" --> NAT_FW[NAT & FW]
+    NAT_FW --- P1[STUN server | P-CSCF]
+    NAT_FW --- P2[STUN server | P-CSCF]
+    NAT_FW -.-> P3[STUN server | P-CSCF]
+    P1 --- S[S-CSCF/Registrar]
+    P2 --- S
+    P3 --- S
+  
+```
+
+Diagram illustrating NAT traversal for SIP signalling. A User Equipment (UE) connects to a NAT & FW box. From the NAT & FW box, multiple paths lead to different P-CSCF boxes, each containing a STUN server. All P-CSCF boxes then connect to a central S-CSCF/Registrar box. SIP signalling is shown entering the NAT & FW box from the UE.
+
+J.360\_FV.4
+
+**Figure V.4 – NAT traversal for SIP signalling**
+
+As illustrated in Figure V.4, a UE may be able to connect to any number of P-CSCFs. However, in order for the UE to receive incoming calls, the signalling must follow a path for which there is an existing NAT binding. Several such bindings may exist over multiple flows to edge proxies (e.g., for redundancy purposes). The problems of NAT traversal for SIP signalling then involve:
+
+- Establishing an outbound connection: Setting up one or more signalling connections or flows to P-CSCF;
+- Maintaining the NAT bindings and keeping FW pinholes open for those flows; and
+- Inbound signalling: Being able to route the signalling to an appropriate P-CSCF and from there to the UE over a flow for which there is an existing NAT binding.
+
+##### V.8.2.2.1 Establishing an outbound connection
+
+SIP registration is used to set up an outbound connection and establish NAT bindings for that flow. During registration:
+
+- The UE establishes a unique instance-id that remains constant over re-boots.
+- The UE also uses a reg-id as described in [ID OUTBOUND] in order to identify each flow that is established with a P-CSCF. STUN is used to keep the flow (i.e., the NAT bindings and pin-holes) alive.
+- The UE includes the instance-id and the reg-id when it registers. If it registers over multiple flows, then it would use the same instance-id, but a different flow-id for that different flow.
+- The P-CSCF that forwards the REGISTER and includes a Path header [ID OUTBOUND] in order to establish a signalling path between P-CSCF that is terminating the specific connection/flow and the S-CSCF/Registrar. The P-CSCF includes within the user portion of
+
+a loose route in the path header a unique identifier to identify the flow over which the registration occurs. The P-CSCF then maps any future requests that include that identifier to that flow.
+
+The Registrar stores:
+
+- The instance-id and reg-id as part of the contact information in addition to the time the binding was last updated.
+- The Path header.
+
+Note that multiple registrations across alternative flows (different reg-ids) allow the UE to pre-establish redundant signalling channels.
+
+In the case where unregistered UEs are allowed to establish dialogs (e.g., emergency calls, subscribing to configuration profiles, etc.), any signalling during the life-time of that session must be maintained over the flow established for that session. This puts a requirement on the P-CSCF to record route and to ensure that signalling for that session occurs over that flow until the session ends.
+
+##### **V.8.2.2.2 Maintaining NAT bindings**
+
+As indicated above, STUN is used by the UE in order to:
+
+- maintain the NAT bindings and keeping FW pinholes open for the signalling;
+- determine if there is a failure of the connection; and
+- determine if the NAT binding has changed as a result of a NAT re-boot.
+
+The STUN server runs on the P-CSCF on the same port that is used for signalling for that flow. The UE makes STUN requests over the flow as a keep-alive mechanism for the flow as well as to determine if NAT bindings have changed as a result of a NAT re-boot.
+
+##### **V.8.2.2.3 Inbound signalling**
+
+Note that signalling in both directions must be established over a flow with existing NAT bindings. In the case of UDP, this implies that SIP messages are sent and received over the same UDP port.
+
+As a result of registrations, the S-CSCF/Registrar is able to maintain contact information (including reg-ids) and path headers in order to be able to access a given UE instance over one or more flows. Therefore, it can route an incoming call to a UE instance over a given flow; and if that fails, do a re-try over an alternative flow.
+
+# **Appendix VI**
+
+# **IPCablecom2 IPv6 and IPv4 strategy overview**
+
+(This appendix does not form an integral part of this Recommendation)
+
+*For further study.*
+
+
+
+
+
+## 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.366.0**
+
+(11/2006)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+IPCablecom
+
+---
+
+**IPCablecom2 IP Multimedia Subsystem (IMS):  
+Delta Recommendations overview**
+
+ITU-T Recommendation J.366.0
+
+
+
+# **ITU-T Recommendation J.366.0**
+
+# **IPCablecom2 IP Multimedia Subsystem (IMS): Delta Recommendations overview**
+
+## **Summary**
+
+This Recommendation is an overview document introducing the family of IMS delta Recommendations that adapt the wireless industries IMS initiative to the needs of the cable industry. A delta Recommendation references another document and then shows only the changes necessary to adapt the other document to the current needs.
+
+## **Source**
+
+ITU-T Recommendation J.366.0 was approved on 29 November 2006 by ITU-T Study Group 9 (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, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2007
+
+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    |
+| 2.1 Normative references.....      | 1    |
+| 2.2 Informative references.....    | 1    |
+| 3 Definitions .....                | 1    |
+| 4 Abbreviations and acronyms ..... | 1    |
+| 5 Introduction .....               | 1    |
+| 6 Recommendations .....            | 2    |
+
+
+
+# **IPCablecom2 IP Multimedia Subsystem (IMS): Delta Recommendations overview**
+
+# **1 Scope**
+
+This Recommendation is an overview document introducing the family of IMS delta Recommendations that adapt the wireless industries IMS initiative to the needs of the cable industry. A delta Recommendation references another document and then shows only the changes necessary to adapt the other document to the current needs.
+
+It is an important objective of this work that interoperability between IPCablecom 2.0 and 3GPP IMS is provided. IPCablecom 2.0 is based upon 3GPP IMS, but includes additional functionality necessary to meet the requirements of cable operators. Recognizing developing converged solutions for wireless, wireline, and cable, it is expected that further development of IPCablecom 2.0 will continue to monitor and contribute to IMS developments in 3GPP, with the aim of alignment of 3GPP IMS and IPCablecom 2.0.
+
+# **2 References**
+
+## **2.1 Normative references**
+
+None.
+
+## **2.2 Informative references**
+
+- ITU-T Recommendation J.360 (2006), *IPCablecom2 Architecture Framework – Main document*.
+- 3GPP TS 23.002, *Network architecture*.
+
+# **3 Definitions**
+
+This Recommendation does not define any terms.
+
+# **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms.
+
+|      |                                         |
+|------|-----------------------------------------|
+| 3GPP | Third Generation Partnership Project    |
+| GSM  | Global System for Mobile Communications |
+| IMS  | IP Multimedia Subsystem                 |
+| SIP  | Session Initiation Protocol             |
+| TS   | Technical Specification                 |
+
+# **5 Introduction**
+
+Interworking with other networks, particularly wireless networks, and reducing development cost are two of the main factors driving the choice of technologies for IPCablecom2. With these objectives in mind, it was agreed to base IPCablecom2 on Release 6 (the latest available at the time work started) of the IP Multimedia Subsystem (IMS) as defined by the 3rd Generation Partnership Project (3GPP). 3GPP is a collaboration agreement between various standards bodies. The scope of
+
+3GPP is to produce Technical Specifications and Technical Reports for GSM and 3rd Generation (3G) Mobile System networks.
+
+The scope of 3GPP includes development of a SIP-based IP-communications architecture for mobile networks. The resulting architecture, dubbed the IP Multimedia Subsystem, defines how various protocols (e.g., SIP and DIAMETER) can be used in a system-level architecture to provide SIP-based communication services.
+
+While many of the functional entities and reference points defined in the IMS have broad applicability in other industries, Release 6 of the IMS is a wireless-centric architecture, designed to meet the business and operational needs of the wireless industry. Therefore, it does not meet all of the needs of the cable industry. IPCablecom2 enhances the IMS to support the unique technology requirements of the cable industry, and also addresses cable operator business and operating requirements.
+
+3GPP is developing newer releases of the IMS specifications. Future updates to IPCablecom2 will align with these newer releases as necessary.
+
+Refer to 3GPP TS 23.002 (Network architecture) for additional information on the 3GPP IMS architecture and to ITU-T Rec. J.360 for additional information on IPCablecom2.
+
+Since the changes to the 3GPP specifications are relatively minor, the 3GPP specifications have been referenced with only the changes needed by the cable industry shown: hence the use of delta Recommendations.
+
+# 6 Recommendations
+
+| IMS Delta Recommendations | Document Name                                                                                                                                                |
+|---------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| J.366.0                   | IPCablecom2 IP Multimedia Subsystem (IMS): Delta Recommendations overview                                                                                    |
+| J.366.1                   | IPCablecom2 IP Multimedia Subsystem (IMS): Organization of subscriber data (3GPP TS 23.008)                                                                  |
+| J.366.2                   | IPCablecom2 IP Multimedia Subsystem (IMS): Session handling – IM call model – Stage 2 specification (3GPP TS 23.218)                                         |
+| J.366.3                   | IPCablecom2 IP Multimedia Subsystem (IMS): Stage 2 specification (3GPP TS 23.228)                                                                            |
+| J.366.4                   | IPCablecom2 IP Multimedia Subsystem (IMS): Session Initiation Protocol (SIP) and Session Description Protocol (SDP) – Stage 3 specification (3GPP TS 24.229) |
+| J.366.5                   | IPCablecom2 IP Multimedia Subsystem (IMS): Cx and Dx interfaces – Signalling flows and message contents (3GPP TS 29.228)                                     |
+| J.366.6                   | IPCablecom2 IP Multimedia Subsystem (IMS): Cx and Dx interfaces based on the Diameter protocol – Protocol details (3GPP TS 29.229)                           |
+| J.366.7                   | IPCablecom2 IP Multimedia Subsystem (IMS): Access security for IP-based services (3GPP TS 33.203)                                                            |
+| J.366.8                   | IPCablecom2 IP Multimedia Subsystem (IMS): Network domain security specification (3GPP TS 33.210)                                                            |
+| J.366.9                   | IPCablecom2 IP Multimedia Subsystem (IMS): Generic authentication architecture specification (3GPP TS 33.220)                                                |
+
+
+
+## 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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+
+
+**ITU-T**
+
+**J.366.8**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+(11/2006)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+IPCablecom
+
+---
+
+**IPCablecom2 IP Multimedia Subsystem (IMS):  
+Network domain security specification**
+
+ITU-T Recommendation J.366.8
+
+
+
+# **ITU-T Recommendation J.366.8**
+
+# **IPCablecom2 IP Multimedia Subsystem (IMS): Network domain security specification**
+
+## **Summary**
+
+This Recommendation introduces a new IPCablecom2 Recommendation to define the security architecture for the UMTS network domain IP-based control plane. The scope of the UMTS network domain control plane security is to cover the control signalling on selected interfaces between UMTS network elements.
+
+The Third Generation Partnership Project (3GPP) has developed the specification in a form optimized for the wireless environment. This Recommendation references the ETSI version of the 3GPP specification and specifies only the modifications necessary to optimize it for the cable environment.
+
+###### **Source**
+
+ITU-T Recommendation J.366.8 was approved on 29 November 2006 by ITU-T Study Group 9 (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, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2007
+
+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, symbols and abbreviations.....                                            | 1    |
+| 3.1 Definitions.....                                                                     | 1    |
+| 3.2 Symbols.....                                                                         | 1    |
+| 3.3 Abbreviations .....                                                                  | 2    |
+| 4 Overview over UMTS network domain security for IP based protocols .....                | 2    |
+| 4.1 Introduction.....                                                                    | 2    |
+| 4.2 Protection at the network layer .....                                                | 2    |
+| 4.3 Security for native IP-based protocols .....                                         | 2    |
+| 4.4 Security domains.....                                                                | 2    |
+| 4.5 Security Gateways (SEGs).....                                                        | 2    |
+| 5 Key management and distribution architecture for NDS/IP.....                           | 2    |
+| 5.1 Security services afforded to the protocols .....                                    | 2    |
+| 5.2 Security Associations (SAs) .....                                                    | 2    |
+| 5.3 Profiling of IPsec .....                                                             | 3    |
+| 5.4 Profiling of IKE .....                                                               | 3    |
+| 5.5 Security policy granularity.....                                                     | 3    |
+| 5.6 UMTS key management and distribution architecture for native IP based protocols..... | 3    |
+| 6 <a href="#">TLS Option for Protection of Intra-Network SIP</a> .....                   | 4    |
+| 6.1 <a href="#">TLS Authentication Algorithms</a> .....                                  | 4    |
+| 6.2 <a href="#">Key Exchange Algorithms for TLS</a> .....                                | 4    |
+| 6.3 <a href="#">Random Number Generator for TLS</a> .....                                | 4    |
+| 6.4 <a href="#">TLS Encryption Algorithms</a> .....                                      | 5    |
+| 6.5 <a href="#">Ciphersuites for TLS</a> .....                                           | 5    |
+| 6.6 <a href="#">TLS Authentication</a> .....                                             | 5    |
+| 6.7 <a href="#">TLS Certificate Profile</a> .....                                        | 6    |
+| 6.8 <a href="#">Certificate Validation</a> .....                                         | 6    |
+| 6.9 <a href="#">Certificate Revocation</a> .....                                         | 6    |
+| Annexes A-D.....                                                                         | 7    |
+
+
+
+# **IPCablecom2 IP Multimedia Subsystem (IMS): Network domain security specification**
+
+# **1 Scope**
+
+This Recommendation defines the security architecture for the UMTS network domain IP-based control plane. The scope of the UMTS network domain control plane security is to cover the control signalling on selected interfaces between UMTS network elements.
+
+The Third Generation Partnership Project (3GPP) has developed the specification in a form optimized for the wireless environment. This Recommendation references the ETSI version of the 3GPP specification and specifies only the modifications necessary to optimize it for the cable environment. Additions are shown in blue underline and deletions in ~~red strikethrough~~.
+
+It is an important objective of this work that interoperability between IPCablecom 2.0 and 3GPP IMS is provided. IPCablecom 2.0 is based upon 3GPP IMS, but includes additional functionality necessary to meet the requirements of cable operators. Recognizing developing converged solutions for wireless, wireline, and cable, it is expected that further development of IPCablecom 2.0 will continue to monitor and contribute to IMS developments in 3GPP, with the aim of alignment of 3GPP IMS and IPCablecom 2.0.
+
+The modifications to ETSI TS 133.210 V6.5 (2005-01) Network Domain Security Specification are listed below.
+
+# **2 References**
+
+<<Add the following references>>
+
+- [30] RFC 2246 "The TLS Protocol Version 1".
+- [31] RFC 3268 "AES Ciphersuites for TLS".
+- [32] RFC 3261 "SIP: Session Initiation Protocol".
+- [33] RFC 3546 "Transport Layer Security (TLS) Extensions".
+- [34] RFC 1750 "Randomness Recommendations for Security".
+- [35] RFC 3280 "Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile".
+
+# **3 Definitions, symbols and abbreviations**
+
+## **3.1 Definitions**
+
+<<No Change>>.
+
+## **3.2 Symbols**
+
+<<No Change>>.
+
+## **3.3 Abbreviations**
+
+<<Add the following abbreviations>>
+
+3DES Triple DES – a block cipher formed from the Data Encryption Standard (DES) cipher
+
+CA Certification Authority
+
+CBC Cipher Block Chaining
+
+CRL Certificate Revocation List
+
+DH Diffie-Hellman
+
+EDE A 3DES mode where the data is encrypted, decrypted and encrypted
+
+RSA An algorithm for public-key encryption invented by Ron Rivest, Adi Shamir and Len Adleman
+
+SHA Secure Hash Algorithm
+
+TLS Transport Layer Security
+
+# **4 Overview over UMTS network domain security for IP-based protocols**
+
+## **4.1 Introduction**
+
+<<No Change>>.
+
+## **4.2 Protection at the network layer**
+
+For native IP-based protocols, security shall be provided at the network layer. The security protocols to be used at the network layer are the IETF defined IPsec security protocols as specified in RFC 2401 [12]. Optionally, for the Zb interface, TLS may be used instead of or in addition to IPsec, as described in clause 6.
+
+## **4.3 Security for native IP-based protocols**
+
+<<No Change>>.
+
+## **4.4 Security domains**
+
+<<No Change>>.
+
+## **4.5 Security Gateways (SEGs)**
+
+<<No Change>>.
+
+# **5 Key management and distribution architecture for NDS/IP**
+
+## **5.1 Security services afforded to the protocols**
+
+<<No Change>>.
+
+## **5.2 Security Associations (SAs)**
+
+<<No Change>>.
+
+## 5.3 Profiling of IPsec
+
+<<No Change>>.
+
+## 5.4 Profiling of IKE
+
+<<No Change>>.
+
+## 5.5 Security policy granularity
+
+<<No Change>>.
+
+## 5.6 UMTS key management and distribution architecture for native IP-based protocols
+
+### 5.6.1 Network domain security architecture outline
+
+<<No Change>>.
+
+### 5.6.2 Interface description
+
+The following interfaces are defined for protection of native IP-based protocols:
+
+#### – Za-interface (SEG-SEG)
+
+The Za-interface covers all NDS/IP traffic between security domains. On the Za-interface, authentication/integrity protection is mandatory and encryption is recommended. ESP shall be used for providing authentication/integrity protection and encryption. The SEGs use IKE to negotiate, establish and maintain a secure ESP tunnel between them. The tunnel is subsequently used for forwarding NDS/IP traffic between security domain A and security domain B. Inter-SEG tunnels can be available at all times, but they can also be established as needed.
+
+One SEG of security domain A can be dedicated to only serve a certain subset of security domains that security domain A needs to communicate with. This will limit the number of SAs and tunnels that need to be maintained.
+
+All security domains compliant with this specification shall operate the Za-interface.
+
+#### – Zb-interface (NE-SEG / NE-NE)
+
+The Zb-interface is located between SEGs and NEs and between NEs within the same security domain. The Zb-interface is optional for implementation. If implemented, it shall implement ESP+IKE [or TLS](#).
+
+On the Zb-interface, ESP shall always be used with authentication/integrity protection. The use of encryption is optional. The ESP Security Association shall be used for all control plane traffic that needs security protection.
+
+Whether the Security Association is established when needed or *a priori* is for the security domain operator to decide. The Security Association is subsequently used for exchange of NDS/IP traffic between the NEs.
+
+NOTE 1 – The security policy established over the Za-interface may be subject to roaming agreements. This differs from the security policy enforced over the Zb-interface, which is unilaterally decided by the security domain operator.
+
+NOTE 2 – There is normally no NE-NE interface for NEs belonging to separate security domains. This is because it is important to have a clear separation between the security domains. This is particularly relevant when different security policies are employed ~~whithin~~[within](#) the security domain and towards external destinations.
+
+The restriction not to allow secure inter-domain NE-NE communication does not preclude a single physical entity to contain both NE and SEG functionality. It is observed that SEGs are responsible for enforcing security policies towards external destinations and that a combined NE/SEG would have the same responsibility towards external destinations. The exact SEG functionality required to allow for secure inter-domain NE $\leftrightarrow$ NE communication will be subject to the actual security policies being employed. Thus, it will be possible to have secure direct inter-domain NE $\leftrightarrow$ NE communication within the framework of NDS/IP if both NEs have implemented SEG functionality. If a NE and SEG is combined in one physical entity, the SEG functionality of the combined unit should not be used by other NEs towards external security domains.
+
+# **6 TLS Option for Protection of Intra-Network SIP**
+
+The use of TLS is optional. TLS may be supported on the Zb interface (see Figure 1) for security of intra-network TCP interfaces.
+
+The TLS protocol provides privacy and data integrity over a reliable transport layer protocol such as TCP. This means that UDP-based protocols will not be able to use TLS. The protocol is composed of two layers: the TLS Record Protocol and the TLS Handshake Protocol. The TLS Record Protocol is used to securely encapsulate upper layer protocols, while the TLS Handshake Protocol provides the key management functionality required to establish and manage TLS sessions.
+
+If TLS is supported, the NE shall implement the requirements specified in this clause. Unless specified within this clause, interfaces requiring TLS shall be compliant with the TLS specification [30]. Additionally, SIP interface that requires TLS shall comply with any requirements specified in [32] relating to the usage of TLS in SIP.
+
+TLS [30] supports the negotiation and use of compression methods. However, since these methods are not specified within TLS [30], compression shall not be used.
+
+Note that TLS is the IETF standardized successor to the Secure Socket Layer (SSL) protocol. TLS has security enhancements over the SSL protocol. See [30], [31], and [33].
+
+## **6.1 TLS Authentication Algorithms**
+
+The HMAC-SHA-1 (with 160-bit key) algorithm shall be supported in order to provide data origin authentication and data integrity services in TLS. AES-XCBC is not required.
+
+## **6.2 Key Exchange Algorithms for TLS**
+
+Following are the requirements relating to methods for key exchange within the TLS protocol:
+
+- RSA shall be supported;
+- Diffie-Hellman (DH) shall be supported.
+
+## **6.3 Random Number Generator for TLS**
+
+Random number generation implementations tend to be weak. Many semiconductor manufacturers are adding secure random number generators to their integrated circuits, which should be used if available. If no hardware is available, strong pseudo-random number generator software may optionally be used following the guidelines in [34].
+
+Following are the requirements relating to random number generation:
+
+- A hardware random number generator may be supported.
+- Pseudo-random number generator software shall be supported if a hardware random number generator is not supported.
+
+## **6.4 TLS Encryption Algorithms**
+
+Following are the TLS Client and TLS Server requirements related to encryption algorithms:
+
+- 3DES CBC-mode (with 3 independent 56-bit keys) shall be supported.
+- AES CBC (with 128-bit key) shall be supported.
+- Null encryption may be supported.
+
+## **6.5 Ciphersuites for TLS**
+
+TLS specifies various ciphersuites for use within the TLS protocol, as discussed in detail in [31]. Ciphersuites represent the recommended combinations of encryption, authentication, and key exchange algorithms to be used within the TLS protocol.
+
+Following are the requirements related to Ciphersuites for TLS:
+
+- "TLS\_RSA\_WITH\_AES\_128\_CBC\_SHA" shall be supported.
+- "TLS\_DH\_RSA\_WITH\_AES\_128\_CBC\_SHA" shall be supported.
+- "TLS\_RSA\_WITH\_3DES\_EDE\_CBC\_SHA" should be supported.
+- "TLS\_DH\_RSA\_WITH\_3DES\_EDE\_CBC\_SHA" should be supported.
+- "TLS\_RSA\_WITH\_NULL\_SHA" may be supported.
+
+## **6.6 TLS Authentication**
+
+TLS allows either unidirectional authentication where the server is authenticated to the client only, or bidirectional authentication where both client and server authenticate to each other. Unidirectional authentication is the usual method used in the public Internet; however, for network signalling and control applications, bidirectional authentication is mandatory to allow both parties to know they are communicating with the desired endpoint.
+
+Following is the requirement related to TLS authentication:
+
+- Bidirectional authentication for TLS applications shall be supported.
+
+## **6.7 TLS Certificate Profile**
+
+X.509 digital certificates [35] are used for authentication in TLS. All X.509 certificates should be signed by a trusted party.
+
+**Table 1a/J.366.8 – TLS Certificate Profile**
+
+| <b><u>Server Certificates</u></b> |                                                                                                                                                                                                                                                                                      |
+|-----------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| <u>Subject Name Form</u>          | <u>C=&lt;Country&gt;</u><br><u>O=&lt;Company&gt;</u><br><u>CN=&lt;FQDN&gt;</u><br><u>Additional fields may be present in the subject name.</u><br><u>FQDN is the server's fully qualified domain name (e.g., server.example.com). Only a single FQDN is allowed in the CN field.</u> |
+| <u>Intended Usage</u>             | <u>These certificates are used to authenticate TLS handshake exchanges (and encrypt when using RSA key exchange).</u>                                                                                                                                                                |
+| <u>Validity Period</u>            | <u>Set by operator policy</u>                                                                                                                                                                                                                                                        |
+| <u>Modulus Length</u>             | <u>1024, 1536, 2048</u>                                                                                                                                                                                                                                                              |
+| <u>Extensions</u>                 | <u>KeyUsage[critical](digitalSignature, keyEncipherment)</u><br><u>extendedKeyUsage[critical](id-kp-serverAuth, id-kp-clientAuth)</u><br><u>authorityKeyIdentifier[critical](keyIdentifier=&lt;subjectKeyIdentifier value from CA cert&gt;)</u>                                      |
+
+## **6.8 Certificate Validation**
+
+TLS certificates shall be verified as part of a certificate chain that chains up to a trusted Root certificate. The chain may contain intermediate Certification Authority (CA) certificates. Usually the first certificate in the chain is not explicitly included in the certificate chain that is sent over the wire. In the cases where the first certificate is explicitly included, it shall already be known to the verifying party ahead of time and shall not contain any changes to the certificate, with the possible exception of the certificate serial number, validity period and the value of the signature. If changes other than the certificate serial number, validity period and the value of the signature, exist in the root certificate that was passed over the wire in comparison to the known root certificate, the device making the comparison shall fail the certificate verification.
+
+The NE shall build the certificate chain and validate the TLS certificate according to the "Certificate Path Validation" procedures described in [35]. In general, X.509 certificates support a liberal set of rules for determining if the issuer name of a certificate matches the subject name of another. The rules are such that two name fields may be declared to match even though a binary comparison of the two name fields does not indicate a match. RFC 3280 [35] recommends that certificate authorities restrict the encoding of name fields so that an implementation can declare a match or mismatch using simple binary comparison. Accordingly, the DER-encoded tbsCertificate.issuer field of a certificate shall be an exact match to the DER-encoded tbsCertificate.subject field of its issuer certificate. An implementation may compare an issuer name to a subject name by performing a binary comparison of the DER-encoded tbsCertificate.issuer and tbsCertificate.subject fields.
+
+## **6.9 Certificate Revocation**
+
+Certificate Revocation Lists (CRLs) may be checked as part of certificate path validation. The CRL profile and how a NE obtains a CRL is not defined.
+
+# **Annexes A-D**
+
+<<No Changes>>.
+
+
+
+
+
+## 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.382**
+
+(03/2018)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Digital transmission of television signals – Part 3
+
+---
+
+**Advanced digital downstream transmission  
+systems for television, sound and data services  
+for cable distribution**
+
+Recommendation ITU-T J.382
+
+
+
+# Recommendation ITU-T J.382
+
+# Advanced digital downstream transmission systems for television, sound and data services for cable distribution
+
+## Summary
+
+Recommendation ITU-T J.382 provides specifications that should be considered for advanced digital cable downstream transmission technologies to provide high spectral efficiency schemes saving transmission resources for downstream in hybrid fibre coax (HFC) based networks.
+
+This Recommendation covers the common definition of framing structure, channel coding and modulation for television, sound and data services including high quality broadcast and multicast services distributed through HFC based networks.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T J.382    | 2014-01-13 | 9           | <a href="http://handle.itu.int/11.1002/1000/12104">11.1002/1000/12104</a> |
+| 2.0     | ITU-T J.382    | 2018-03-16 | 9           | <a href="http://handle.itu.int/11.1002/1000/13563">11.1002/1000/13563</a> |
+
+## Keywords
+
+Advanced transmission systems, cable distribution, DVB-C2, HFC, OFDM.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2018
+
+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 .....                                                                                                                                                  | 1    |
+| 5 Conventions .....                                                                                                                                                                 | 3    |
+| 6 Advanced digital downstream transmission systems for cable distribution.....                                                                                                      | 3    |
+| 6.1 System concept.....                                                                                                                                                             | 3    |
+| 6.2 Specifications of advanced digital downstream transmission systems .....                                                                                                        | 4    |
+| Appendix I – A digital video broadcasting (DVB); Frame structure channel coding and modulation for a second generation digital transmission system for cable systems (DVB-C2) ..... | 6    |
+| I.1 Introduction .....                                                                                                                                                              | 6    |
+| I.2 Main building blocks of a DVB-C2 modulator .....                                                                                                                                | 7    |
+| I.3 Summary of the key DVB-C2 features .....                                                                                                                                        | 9    |
+| I.4 Cable system concept .....                                                                                                                                                      | 10   |
+| Bibliography.....                                                                                                                                                                   | 12   |
+
+# Introduction
+
+As the demand for high quality broadcast and multicast services from the consumers' side is increasing, cable operators are diligently researching more efficient ways to transmit those services through hybrid fibre coax (HFC) based networks.
+
+Modulation and coding schemes for global use in cable industry are based on [b-ITU-T J.83], which was developed and deployed in the 1990s. These technologies, specified in [b-ITU-T J.83], can support up to 38 Mbit/s per 6 MHz channel when using a 256 quadrature amplitude modulation (QAM) modulation scheme and thus do not serve demands for advanced digital downstream transmission systems.
+
+In the near future, advanced digital transmission systems including enhanced coding and modulation, can replace digital cable transmission systems defined in [b-ITU-T J.83].
+
+## Recommendation ITU-T J.382
+
+## Advanced digital downstream transmission systems for television, sound and data services for cable distribution
+
+# 1 Scope
+
+The scope of this Recommendation is to define a globally common specification for framing structure, channel coding and modulation schemes for television, sound and data services including high quality broadcast and multicast services for downstream transmission distributed through hybrid fibre coax (HFC) based networks to provide high spectral efficiency. This Recommendation will contribute to the development of common products for cable broadcast and telecommunication downstream physical layer (PHY).
+
+The specifications included in this Recommendation are based on the requirements defined in [ITU-T J.381].
+
+# 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 J.381] Recommendation ITU-T J.381 (2012), *Requirements for advanced digital transmission technologies*.
+
+[ETSI EN 302 769] ETSI EN 302 769 V1.3.1 (2015), *Digital Video Broadcasting (DVB) – Frame structure channel coding and modulation for a second generation digital transmission system for cable systems (DVB-C2)*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following term defined elsewhere:
+
+**3.1.1 HFC-based networks** [ITU-T J.381]: HFC-based networks include legacy cable networks such as hybrid fibre coax; recent technology deployments such as radio frequency over glass (RFoG) and cable network technologies that may be deployed in the near future.
+
+## 3.2 Terms defined in this Recommendation
+
+None.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|         |                                         |
+|---------|-----------------------------------------|
+| 16-QAM  | 16-ary Quadrature Amplitude Modulation  |
+| 64-QAM  | 64-ary Quadrature Amplitude Modulation  |
+| 256-QAM | 256-ary Quadrature Amplitude Modulation |
+
+|          |                                                                        |
+|----------|------------------------------------------------------------------------|
+| 1024-QAM | 1024-ary Quadrature Amplitude Modulation                               |
+| 4096-QAM | 4096-ary Quadrature Amplitude Modulation                               |
+| ACM      | Adaptive Coding and Modulation                                         |
+| ADC      | Analogue-to-Digital Converter                                          |
+| AWGN     | Additive White Gaussian Noise                                          |
+| BB       | Baseband                                                               |
+| BCH      | Bose-Chaudhuri-Hocquenghem multiple error correction binary block code |
+| CCM      | Constant Coding and Modulation                                         |
+| CNR      | Carrier-to-Noise Ratio                                                 |
+| CRC      | Cyclic Redundancy Check                                                |
+| dB       | decibel                                                                |
+| DEMUX    | De-Multiplexer                                                         |
+| DS       | Data Slice                                                             |
+| DVB      | Digital Video Broadcasting                                             |
+| DVB-C    | DVB system for cable transmission                                      |
+| DVB-C2   | DVB system for second generation cable transmission                    |
+| FEC      | Forward Error Correction                                               |
+| FFT      | Fast Fourier Transform                                                 |
+| GI       | Guard Interval                                                         |
+| GSE      | Generic Stream Encapsulation                                           |
+| HFC      | Hybrid Fibre Coax                                                      |
+| IFFT     | Inverse Fast Fourier Transform                                         |
+| IP       | Internet Protocol                                                      |
+| LDPC     | Low Density Parity Check (codes)                                       |
+| MATV     | Master Antenna Television                                              |
+| Mbit     | $2^{20} = 1,048,576$ bits                                              |
+| Mbit/s   | Mbit per second                                                        |
+| MHz      | $10^6$ Hertz                                                           |
+| MPEG     | Moving Pictures Experts Group                                          |
+| OFDM     | Orthogonal Frequency Division Multiplex                                |
+| PAPR     | Peak to Average Power Ratio                                            |
+| PHY      | Physical Layer                                                         |
+| PLP      | Physical Layer Pipe                                                    |
+| QAM      | Quadrature Amplitude Modulation                                        |
+| QoS      | Quality of Service                                                     |
+| RFoG     | Radio Frequency over Glass                                             |
+| SMATV    | Satellite Master Antenna Television                                    |
+
+|     |                                |
+|-----|--------------------------------|
+| SNR | Signal-to-Noise Ratio          |
+| TDM | Time Division Multiplex        |
+| TI  | Time Interleaver               |
+| TS  | Transport Stream               |
+| VCM | Variable Coding and Modulation |
+
+# 5 Conventions
+
+None.
+
+# 6 Advanced digital downstream transmission systems for cable distribution
+
+## 6.1 System concept
+
+A downstream framer, capable of receiving multiple formats of streams, such as MPEG-2 transport streams and Ethernet packet streams, has the function of framing these streams for efficient transmission. A downstream forward error correction (FEC) encoder, followed by a downstream framer, adds an encoding function to protect information data from channel noise through HFC based networks. The downstream modulator covers functions for mapping the high order quadrature amplitude modulation (QAM) constellation in order to improve spectral efficiency, as well as interleaving mechanisms for the protection of information data from burst noise in the time and frequency domain.
+
+The basic block diagram of advanced digital transmission processing is shown in Figure 1.
+
+Input stream does not only represent a single stream, but instead can consist of multiple independent data streams, containing signals and components of advanced digital downstream transmission systems for television, sound and data services for cable distribution.
+
+The channel model of HFC-based networks is primarily a bandwidth-limited linear channel, with a balanced combination of white noise, interference and multi-path distortion. The orthogonal frequency division multiplex (OFDM) technique with channel coding can have advantages to minimize the loss due to typical channel distortions in HFC-based networks.
+
+The advanced digital downstream transmission system shall be fully transparent with respect to the different transmitter inputs and related receiver output signals.
+
+Upstream advanced digital transmission technologies are not covered by this Recommendation.
+
+![Figure 1: System concept for advanced digital downstream transmission system. The diagram shows a Transmitter and a Receiver connected via HFC based networks. The Transmitter consists of an Input stream (MPEG-TS or other streams) entering a Downstream framer, which then connects to a Downstream FEC encoder (LDPC/BCH), which in turn connects to a Downstream modulator (OFDM). The output of the modulator is sent to the HFC based networks. The Receiver consists of a Downstream demodulator receiving from the HFC based networks, which then connects to a Downstream FEC decoder, which finally connects to a Downstream deframer, producing the Output stream.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg)
+
+```
+
+graph LR
+    subgraph Transmitter
+        direction TB
+        T1[Downstream framer] --> T2[Downstream FEC encoder  
+(LDPC/BCH)]
+        T2 --> T3[Downstream modulator  
+(OFDM)]
+    end
+    Input[Input stream  
+MPEG-TS or  
+other streams] --> T1
+    T3 --> HFC((HFC based networks))
+    HFC --> R3[Downstream demodulator]
+    subgraph Receiver
+        direction BT
+        R3 --> R2[Downstream FEC decoder]
+        R2 --> R1[Downstream deframer]
+    end
+    R1 --> Output[Output stream]
+  
+```
+
+J.382(14)\_F01
+
+Figure 1: System concept for advanced digital downstream transmission system. The diagram shows a Transmitter and a Receiver connected via HFC based networks. The Transmitter consists of an Input stream (MPEG-TS or other streams) entering a Downstream framer, which then connects to a Downstream FEC encoder (LDPC/BCH), which in turn connects to a Downstream modulator (OFDM). The output of the modulator is sent to the HFC based networks. The Receiver consists of a Downstream demodulator receiving from the HFC based networks, which then connects to a Downstream FEC decoder, which finally connects to a Downstream deframer, producing the Output stream.
+
+**Figure 1 – System concept for advanced digital downstream transmission system**
+
+## 6.2 Specifications of advanced digital downstream transmission systems
+
+Advanced digital downstream transmission systems are required to support the following technical specifications regarding framing, channel coding and modulation. The fundamental framework is described in Table 1 and extended parameters are defined in Table 2.
+
+**Table 1 – PHY downstream specifications in summary form indicating fundamental framework**
+
+| Item                       | Specification                                                                                            |
+|----------------------------|----------------------------------------------------------------------------------------------------------|
+| Input signals              | MPEG-TS, any packetized or continuous stream                                                             |
+| Framing structure          | Two dimensional time division multiplex (TDM) structure: physical layer pipes (PLPs) and data slice (DS) |
+| Signalling method          | Embedded in the TDM framing structure                                                                    |
+| Modulation scheme          | OFDM                                                                                                     |
+| FFT size                   | 4096 for 8 MHz channel (2.232 kHz carrier spacing) or 4096 for 6 MHz channel (1.674 kHz carrier spacing) |
+| Number of payload carriers | 3408 for a 8 MHz channel                                                                                 |
+| Channel coding             |                                                                                                          |
+| Randomization              | FEC frame scrambling<br>(1 + X <sup>14</sup> + X <sup>15</sup> )                                         |
+| FEC                        | LDPC/BCH                                                                                                 |
+| Interleaving               | Bit-, time and frequency interleaving                                                                    |
+| Modulation                 |                                                                                                          |
+| Bandwidth                  | 6 or 8 MHz basis, flexibility for wider bandwidth (up to 450 MHz)                                        |
+| Constellation              | 16/64/256/1024/4096 – QAM                                                                                |
+| Pilots                     | Scattered, continual and edge-pilots                                                                     |
+| Guard interval (GI)        | 1/64 or 1/128                                                                                            |
+
+**Table 2 – Extended parameters**
+
+| Item           |                                      | Specification                                                                                                                                    |
+|----------------|--------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------|
+| Channel coding | Bit-Interleaving                     | Parity- and column twist Interleaving                                                                                                            |
+|                | Time-Interleaving                    | At data slice (DS) level: Block interleaving with 0, 4, 8, 16 symbols interleaving depth                                                         |
+|                | Frequency-Interleaving               | At DS level                                                                                                                                      |
+|                | Service-related robustness           | Robustness parameters (modulation scheme and FEC parameters) can be chosen per PLP                                                               |
+|                | Variable coding and modulation (VCM) | Modulation parameters may be changed each DVB-C2 Frame                                                                                           |
+|                | Adaptive coding and modulation (ACM) | Possible                                                                                                                                         |
+|                | Two layer multiplexing structure     | Physical layer pipe (PLP): individual modulation parameters data slice (DS): Group of PLPs with individual time-/frequency interleaving settings |
+| Modulation     | Byte to symbol mapping               | Depending on modulation scheme and FEC code rate                                                                                                 |
+|                | Roll-off factor                      | Not defined                                                                                                                                      |
+|                | Baseband filter characteristics      | Not defined                                                                                                                                      |
+|                | Pilots                               | Pilot density depending on guard interval (GI) choice                                                                                            |
+|                | Peak-to-average-power-ratio (PAPR)   | Reduction of PAPR is possible by reserved tones                                                                                                  |
+|                | Hooks for extensions                 | Available                                                                                                                                        |
+
+The frequency allocation is not specified in this Recommendation, however the system is recommended to allow flexibility in order to reflect each country's usage of the frequency space.
+
+The text of [ETSI EN 302 769] is applied with the modifications as given below:
+
+## **Un-numbered clauses "Intellectual Property Rights" and "Foreword"**
+
+The introductory clauses labelled "Intellectual Property Rights" and "Foreword" do not apply in the context of this Recommendation.
+
+# Appendix I
+
+## A digital video broadcasting (DVB); Frame structure channel coding and modulation for a second generation digital transmission system for cable systems (DVB-C2)
+
+(This appendix does not form an integral part of this Recommendation.)
+
+### I.1 Introduction
+
+This appendix derives from work done by the Digital Video Broadcasting (DVB) Project. The specification of the second generation DVB cable transmission system (i.e., DVB-C2) has been adopted by the Joint Technical Committee (JTC) of the European Broadcasting Union (EBU), the Comité Européen de Normalization Electrotechnique (CENELEC) and the European Telecommunications Standards Institute (ETSI) as European Norm [ETSI EN 302 769].
+
+DVB-C2 specifies the framing structure, channel coding and modulation for a second generation digital multi-programme television distribution by cable.
+
+Although the MPEG transport stream (TS) is still the favoured protocol used in digital broadcasting, DVB-C2 supports TS, any packetized and continuous input formats as well as the so called generic stream encapsulation (GSE). All input streams are multiplexed into a baseband (BB) frame format. The forward error correction (FEC) scheme is applied to these BB frames. In line with the other DVB-X2 systems, DVB-C2 uses a combination of low density parity check (LDPC) and BCH codes, which is a very powerful FEC method providing about a 6 dB improvement of signal-to-noise ratio (SNR) with reference to DVB-C. Appropriate bit-interleaving schemes optimise the overall robustness of the FEC system. Extended by a header, those frames are called physical layer pipes (PLPs). One or several of such PLPs are multiplexed into a data slice (DS). A two-dimensional interleaving (in time and frequency domain) is applied to each slice enabling the receiver to eliminate impacts of burst impairments and frequency selective interference such as single frequency ingress. One or several data slices (DSs) compose the payload of a C2-frame. The frame building process includes, inter alia, the insertion of continual and scattered pilots. The first symbol of a DVB-C2 frame, the so-called "Preamble", carries the signalling data. A DVB-C2 receiver will find all relevant configuration data about the structure and the technical parameters of the DVB-C2 signal in the signalling data block in the preamble as well as in the headers of the PLPs. In the following step the OFDM symbols are generated by means of an inverse fast Fourier transform (IFFT). A 4K-IFFT algorithm is applied generating a total of 4096 sub-carriers, 3409 of which are actively used for the transmission of data and pilots within a frequency band of 8 MHz. The guard interval (GI), used between the OFDM symbols, has a relative length of either 1/128 or 1/64 in reference to the symbol length (448  $\mu$ s).
+
+![High level block diagram of a DVB-C2 modulator](853f59c89931a666c07903b31d098277_img.jpg)
+
+The diagram illustrates the high-level architecture of a DVB-C2 modulator. It consists of four sequential processing blocks: 'Input processing' (light green), 'Bit interleaved coding and modulation' (yellow), 'Data slice + frame builder' (green), and 'OFDM generation' (blue). The process begins with 'TS or GSE inputs' entering the 'Input processing' block. The output of this block flows into the 'Bit interleaved coding and modulation' block. This block, along with the 'Data slice + frame builder' block, is enclosed within a dashed orange rectangle labeled 'C2 system'. The output of the 'Data slice + frame builder' block enters the 'OFDM generation' block, which produces the final 'DVB-C2 output'. A small label 'J.382(14)\_Fl.1' is located at the bottom right of the diagram.
+
+High level block diagram of a DVB-C2 modulator
+
+**Figure I.1 – High level block diagram of a DVB-C2 modulator**
+
+Figure I.1 shows the block diagram of a DVB-C2 modulator. The input processing block is able to process a traditional MPEG transport stream or any packetized or continuous input stream. The second block (identified as: Bit interleaved coding as modulation) adds the FEC information and maps the data into cells. The third block (identified as: Data slice + frame builder) covers the
+
+multiplexing of the different input components to the framing structure, whereas in the last block the final OFDM modulation and frequency up-conversion is performed.
+
+### I.2 Main building blocks of a DVB-C2 modulator
+
+The following clauses give a short overview of the functionalities available in the four building blocks identified in Figure I.1.
+
+#### I.2.1 DVB-C2 modulator input processing
+
+![Figure I.2: Building blocks of the input processing part. The diagram shows two main processing paths. The top path shows the overall flow: TS or GSE inputs enter an 'Input processing' block, which is part of a 'C2 system' containing 'Bit interleaved coding and modulation', 'Data slice + frame builder', and 'OFDM generation', leading to the 'DVB-C2 output'. The bottom path details the 'Input processing' steps: 'Input interface' -> 'Stream synchr.' -> 'Null packet deletion' -> 'CRC-8 encoder' -> 'BB header insertion' -> 'BB scrambler' -> 'BB frame'. A reference label J.382(14)_Fl.2 is present.](cab0834804fb031b43865554cc8d06ab_img.jpg)
+
+Figure I.2: Building blocks of the input processing part. The diagram shows two main processing paths. The top path shows the overall flow: TS or GSE inputs enter an 'Input processing' block, which is part of a 'C2 system' containing 'Bit interleaved coding and modulation', 'Data slice + frame builder', and 'OFDM generation', leading to the 'DVB-C2 output'. The bottom path details the 'Input processing' steps: 'Input interface' -> 'Stream synchr.' -> 'Null packet deletion' -> 'CRC-8 encoder' -> 'BB header insertion' -> 'BB scrambler' -> 'BB frame'. A reference label J.382(14)\_Fl.2 is present.
+
+Figure I.2 – Building blocks of the input processing part
+
+Figure I.2 shows the main building blocks of the input processing part for one input signal of a DVB-C2 modulator. Different types of input formats are possible: MPEG transport stream, GSE signals or any continuous or packetized signal format. The signal is synchronized and mapped into a baseband (BB) framing structure. Null packets are deleted in case of MPEG transport streams, a baseband frame header and a cyclic redundancy check (CRC) code are added and the frames are spectrum formed by a scrambler. A baseband (BB) frame is the payload of a physical layer pipe (PLP).
+
+#### I.2.2 Bit interleaved FEC processing and mapping
+
+![Figure I.3: Building blocks of the FEC processing part. The diagram shows two main processing paths. The top path is identical to Figure I.2, showing the overall flow from 'TS or GSE inputs' through the 'C2 system' to 'DVB-C2 output'. The bottom path details the FEC processing: 'BB frame' -> 'BCH FEC encoding' -> 'LDPC FEC encoding' -> 'Bit-interleaver' -> 'DEMUX bit to cell' -> 'Cell to constell. mapper' -> 'FEC frame header' -> 'PLP'. A reference label J.382(14)_Fl.3 is present.](4636adff5682a064f0ae5f13a1d464a6_img.jpg)
+
+Figure I.3: Building blocks of the FEC processing part. The diagram shows two main processing paths. The top path is identical to Figure I.2, showing the overall flow from 'TS or GSE inputs' through the 'C2 system' to 'DVB-C2 output'. The bottom path details the FEC processing: 'BB frame' -> 'BCH FEC encoding' -> 'LDPC FEC encoding' -> 'Bit-interleaver' -> 'DEMUX bit to cell' -> 'Cell to constell. mapper' -> 'FEC frame header' -> 'PLP'. A reference label J.382(14)\_Fl.3 is present.
+
+Figure I.3 – Building blocks of the FEC processing part
+
+Figure I.3 shows the main building blocks of the FEC processing part of a DVB-C2 modulator. Baseband frames are extended by both BCH and LDPC FEC data. The bit stream is de-multiplexed and mapped to QAM cells. A FEC-frame header is added. The output signal of this processing part is called a PLP. A DVB-C2 modulator is able to process multiple PLPs.
+
+#### I.2.3 Data slice and frame builder
+
+![Figure I.4: Building blocks of the data slice building part. The diagram shows two main paths. The top path, labeled 'C2 system', takes 'TS or GSE inputs' through 'Input processing', 'Bit interleaved coding and modulation', 'Data slice + frame builder', and 'OFDM generation' to produce a 'DVB-C2 output'. The bottom path takes multiple 'PLP' inputs (PLP 1, PLP 2, ..., PLP n) into a 'Data slice builder', which then passes through 'Time interleaving' and 'Frequency interleaving' to produce a 'Data slice'. A reference label 'J.382(14)_Fl.4' is present.](b9ecbc3baefab13719e000faa6e0c7eb_img.jpg)
+
+Figure I.4: Building blocks of the data slice building part. The diagram shows two main paths. The top path, labeled 'C2 system', takes 'TS or GSE inputs' through 'Input processing', 'Bit interleaved coding and modulation', 'Data slice + frame builder', and 'OFDM generation' to produce a 'DVB-C2 output'. The bottom path takes multiple 'PLP' inputs (PLP 1, PLP 2, ..., PLP n) into a 'Data slice builder', which then passes through 'Time interleaving' and 'Frequency interleaving' to produce a 'Data slice'. A reference label 'J.382(14)\_Fl.4' is present.
+
+**Figure I.4 – Building blocks of the data slice building part**
+
+Figure I.4 shows the data slice builder, which multiplexes different PLPs to one data slice. Per data slice (DS), time- and frequency interleaving is applied. A DVB-C2 modulator is able to process multiple data slices, as shown in Figure I.5. The frame builder multiplexes the different data slices (DSs) into a DVB-C2 frame. Furthermore, the frame builder adds pilot signals components and the preamble, which carries the DVB-C2 signalling data, the DVB-C2 frame.
+
+![Figure I.5: Building blocks of the frame building part. The top part shows the 'C2 system' block (Input processing, Bit interleaved coding and modulation, Data slice + frame builder, OFDM generation) taking 'TS or GSE inputs' and producing a 'DVB-C2 output'. The bottom part shows 'Data slice 1', 'Data slice 2', ..., 'Data slice m' entering a 'Frame Builder'. 'Pilot insertion' and 'Preamble insertion' blocks also feed into the 'Frame Builder', which outputs a 'C2-Frame'. A reference label 'J.382(14)_Fl.5' is present.](bd671b21db63e6fdb2196e9b18502aac_img.jpg)
+
+Figure I.5: Building blocks of the frame building part. The top part shows the 'C2 system' block (Input processing, Bit interleaved coding and modulation, Data slice + frame builder, OFDM generation) taking 'TS or GSE inputs' and producing a 'DVB-C2 output'. The bottom part shows 'Data slice 1', 'Data slice 2', ..., 'Data slice m' entering a 'Frame Builder'. 'Pilot insertion' and 'Preamble insertion' blocks also feed into the 'Frame Builder', which outputs a 'C2-Frame'. A reference label 'J.382(14)\_Fl.5' is present.
+
+**Figure I.5 – Building blocks of the frame building part**
+
+#### I.2.4 OFDM generation
+
+![Figure I.6: Building blocks of the OFDM generation part. The top part shows the 'C2 system' block (Input processing, Bit interleaved coding and modulation, Data slice + frame builder, OFDM generation) taking 'TS or GSE inputs' and producing a 'DVB-C2 output'. The bottom part shows the 'C2-Frame' passing through 'Inverse FFT', 'Reserved tone insertion', 'Guard interval insertion', and 'Digital to analogue converter' to produce a 'DVB-C2 to RF converter'. Reference labels 'J.382(14)_Fl.6' and 'J.382(14)_Fl.4' are present.](16c1175b5f05a4b55e6d396fc51b15b3_img.jpg)
+
+Figure I.6: Building blocks of the OFDM generation part. The top part shows the 'C2 system' block (Input processing, Bit interleaved coding and modulation, Data slice + frame builder, OFDM generation) taking 'TS or GSE inputs' and producing a 'DVB-C2 output'. The bottom part shows the 'C2-Frame' passing through 'Inverse FFT', 'Reserved tone insertion', 'Guard interval insertion', and 'Digital to analogue converter' to produce a 'DVB-C2 to RF converter'. Reference labels 'J.382(14)\_Fl.6' and 'J.382(14)\_Fl.4' are present.
+
+**Figure I.6 – Building blocks of the OFDM generation part**
+
+Figure I.6 shows the main building blocks of the OFDM generation unit of a DVB-C2 modulator. After the inverse fast Fourier transform (IFFT) processing, the guard interval is added and an analogue-to-digital conversion is carried out. In the unlikely event of high peak-to-average power ratio (PAPR), reserved tone symbols can be inserted.
+
+### **I.3 Summary of the key DVB-C2 features**
+
+#### **I.3.1 Single pipe versus multiple pipes and formats**
+
+The first generation transmission systems were designed to carry one MPEG transport stream. One key requirement for DVB-C2 was to implement significantly more flexibility in terms of supporting multiple input signals and in terms of supporting more packetized and even continuous input formats, including IP. The flexibility allows the integration of different input signals in physical layer pipes (PLPs) and to bundle PLPs in data slices (DSs). DVB-C2 provides a very flexible multiplexing scheme, capable of supporting future complex services.
+
+#### **I.3.2 Orthogonal frequency division multiplexing (OFDM) modulation**
+
+Although single carrier QAM-modulation was successful for many years in digital cable transmission systems, DVB has taken the decision to choose orthogonal frequency division multiplex (OFDM) because of its excellent spectrum efficiency and superb flexibility.
+
+#### **I.3.3 Low density parity check (LDPC) code for FEC**
+
+The chosen forward error correction (FEC) scheme is a combination of low density parity check (LDPC) code as the inner code and Bose Chaudhuri Hoquenghem (BCH) code as the outer code. The combination is both very powerful and efficient in relation to typical and relevant interference scenarios in cable networks. The excellent performance of the chosen FEC-scheme is the major reason for the significantly higher spectrum efficiency of DVB-C2. Those state of the art FEC codes are very complex. The LDPC-FEC processing part will require about half of the chip size of a DVB-C2 demodulator.
+
+#### **I.3.4 From 16-QAM to 4096-QAM constellations**
+
+The requirement and performance figures of cable networks cover a wide range from low cost master antenna TV (MATV) solutions to high quality professional HFC networks. DVB-C2 therefore offers a fine granularity of solutions from very robust modes up to the highest spectrum efficiency that is mainly limited by cost constraints of receiver analogue-to-digital converters (ADCs). Different FEC code rates and QAM-schemes allow the granularity of about 2 dB over the whole range from 15 to 35 dB carrier-to-noise ratio (CNR). Furthermore, higher modulation constellations may be introduced in the future in a backwards compatible way. Hooks are already available for future extensions of DVB-C2.
+
+#### **I.3.5 Fixed 8 MHz versus flexible bandwidth**
+
+Although DVB-C2 is perfectly in line with the European 8 MHz channel raster (and the 6 MHz United States raster) implemented in cable, one of the outstanding features of DVB-C2 is its flexibility in terms of bandwidth allocation. DVB-C2 allows increased spectrum efficiency and broader transmission signals entailing a higher gain for statistical multiplexing while maintaining the support for simple receivers with a fixed 8 MHz (6 MHz in the United States) receiving window for Europe. For the implementation of future broadband tuner concepts, DVB-C2 opens more options for all kinds of broadband applications.
+
+#### **I.3.6 Constant coding and modulation (CCM) versus variable and adaptive coding and modulation (VCM and ACM)**
+
+DVB-C2 offers another dimension of flexibility. Up to now the coding schemes for cable transmission systems were fixed. With DVB-C2 the modulation parameters may vary over time and this variation may even be related to individual services within a transmitted DVB-C2 signal. The first option is to vary the robustness over time. This may be required for different quality of service (QoS) levels. However, it is also possible to adapt the performance of a DVB-C2 transmission to individual requirements of a customer by means of adaptive coding and modulation. The receiving
+
+conditions of an individual customer may be used to adjust the robustness parameters of the DVB-C2 transmission.
+
+#### **I.3.7 Physical layer pipes (PLP), data slices and frames**
+
+In terms of broadband access and in the terms of video quality the end customer demand is permanently growing. From a cable network operator's point of view, bigger pipes are required to transmit the requested services over networks in an efficient way. The big differences between narrowband and broadband services require flexible multiplexing schemes. DVB-C2 therefore offers a two stage multiplexing scheme. Different input signals, converted to so called physical layer pipes (PLPs) are multiplexed to a data slice (DS) and different DSs are combined to a "DVB-C2 frame" in the second stage. So, in simple broadcasting applications a DVB-C2 transmission signal will consist of one PLP and one data slice (DS), in case a single MPEG transport stream has to be transmitted. However, in more complex services configurations DVB-C2 will allow the offering to be structured in PLPs and DSs and would even be able to provide service related robustness and allow that the payload capacity of those PLPs or DSs vary slightly over time.
+
+#### **I.3.8 Two dimensional interleaving in time and frequency domain**
+
+DVB-C2 offers both time and frequency interleaving, which are powerful tools to cope with critical interference scenarios in cable networks.
+
+#### **I.3.9 Signalling issues**
+
+The flexibility of DVB-C2 requires an appropriate signalling scheme, allowing a receiver a fast synchronisation and an easy access to all relevant parameters required to configure the demodulation and decoding of the requested service. All relevant signalling information is transported in the preamble, which is repeated for every DVB-C2 frame.
+
+#### **I.3.10 Backward compatibility**
+
+DVB-C2 is not backward compatible with the System B of [b-ITU-T J.83] (DVB-C) which had also been developed by the DVB consortium. However, it is assumed that all implementations of the second generation cable transmission system will support DVB-C2 and the first generation solutions in parallel. Such an approach would provide backward compatibility during the transition period to the second generation systems.
+
+### **I.4 Cable system concept**
+
+The DVB-C2 system provides a wide range of solutions for all kind of cable networks deployed worldwide. With 16-QAM modulation, very robust modulation schemes for very simple networks (e.g., satellite master antenna television (SMATV) networks) are available, whereas the 4096-QAM modulation scheme can be considered as headroom for future enhanced HFC infrastructures. The granularity of solutions of DVB-C2 is about 2 dB in the range from 12 dB SNR to 35 dB SNR.
+
+With the growing demand of cable customers for more bandwidth, cable operators are forced to upgrade their cable infrastructures. Fibre-based backbone systems are used for the core network. More and more network segments based on coaxial cable are replaced by fibre and so generally fibre gets closer and closer to the customers and coaxial cable is in many cases only used for the so called last mile. Those necessary network upgrades provide not only more available bandwidth per customer due to optimizations of the network topology, but also higher signal quality, which allows the cable operator to deploy a higher order of modulation for their digital services.
+
+The first generation digital cable transmission systems provided neither solutions with state of the art spectrum efficiency nor the flexibility and higher order modulation needed to optimize the throughput of digital data in those upgraded networks.
+
+DVB-C2 provides a fine granularity of solutions very close to the theoretical "Shannon Limit" for all kinds of cable networks, see Figure I.7.
+
+![Line graph showing Overall spectral efficiency [bit/s/Hz] vs Required signal-to-noise ratio [dB] for DVB-C2 performance in an AWGN channel. The graph includes a Theoretical Limit line and data points for 16QAM, 64QAM, 256QAM, 1024QAM, and 4096QAM. The Theoretical Limit is a straight red line. The data points for different QAM schemes show a step-like increase in spectral efficiency as the SNR increases, with 4096QAM achieving the highest efficiency at the highest SNR shown.](1d529a819ad929684331c55eed6673bb_img.jpg)
+
+| Required signal-to-noise ratio [dB] | Theoretical Limit [bit/s/Hz] | 16QAM [bit/s/Hz] | 64QAM [bit/s/Hz] | 256QAM [bit/s/Hz] | 1024QAM [bit/s/Hz] | 4096QAM [bit/s/Hz] |
+|-------------------------------------|------------------------------|------------------|------------------|-------------------|--------------------|--------------------|
+| 10                                  | 3.32                         | 3.32             | -                | -                 | -                  | -                  |
+| 12                                  | 3.97                         | 3.97             | -                | -                 | -                  | -                  |
+| 14                                  | 4.64                         | -                | 3.97             | -                 | -                  | -                  |
+| 16                                  | 5.32                         | -                | 4.64             | -                 | -                  | -                  |
+| 18                                  | 6.01                         | -                | 5.32             | -                 | -                  | -                  |
+| 20                                  | 6.70                         | -                | -                | 5.99              | -                  | -                  |
+| 22                                  | 7.40                         | -                | -                | 6.67              | -                  | -                  |
+| 24                                  | 8.10                         | -                | -                | 7.34              | 7.34               | -                  |
+| 26                                  | 8.81                         | -                | -                | -                 | 8.01               | -                  |
+| 28                                  | 9.52                         | -                | -                | -                 | 8.68               | -                  |
+| 30                                  | 10.23                        | -                | -                | -                 | -                  | 9.99               |
+| 32                                  | 10.94                        | -                | -                | -                 | -                  | 10.66              |
+| 34                                  | 11.66                        | -                | -                | -                 | -                  | 11.33              |
+| 36                                  | 12.37                        | -                | -                | -                 | -                  | -                  |
+
+Line graph showing Overall spectral efficiency [bit/s/Hz] vs Required signal-to-noise ratio [dB] for DVB-C2 performance in an AWGN channel. The graph includes a Theoretical Limit line and data points for 16QAM, 64QAM, 256QAM, 1024QAM, and 4096QAM. The Theoretical Limit is a straight red line. The data points for different QAM schemes show a step-like increase in spectral efficiency as the SNR increases, with 4096QAM achieving the highest efficiency at the highest SNR shown.
+
+**Figure I.7 – DVB-C2 performance in an AWGN channel**
+
+In summary, the key technical features of DVB-C2 are the combination of flexibility and efficiency. It is expected that the deployment of DVB-C2 will on one hand increase the downstream capacity of cable networks by 30% and for optimized networks up to 60%. On the other hand, DVB-C2 will allow network operators to utilize the available frequency resources in a more flexible way and allow the introduction of both enhanced services and bigger pipes, for all kinds of service containers, including the support of IP-based transport mechanisms.
+
+## Bibliography
+
+- [b-ITU-T H.222.0] Recommendation ITU-T H.222.0 (2012) | ISO/IEC 13818-1:2013, *Information technology – Generic coding of moving pictures and associated audio information: Systems.*
+- [b-ITU-T J.83] Recommendation ITU-T J.83 (2007), *Digital multi-programme systems for television, sound and data services for cable distribution.*
+- [b-ITU-T J.112] Recommendation ITU-T J.112 (2004), *Transmission systems for interactive cable television services.*
+- [b-ETSI TS 102 991] TS 102 991 v1.3.1 (2016): *Digital Video Broadcasting (DVB); Implementation Guidelines for a second generation digital cable transmission system (DVB-C2).*  
+[www.etsi.org/deliver/etsi\\_ts/102900\\_102999/102991/01.../ts\\_102991v010301p.pdf](http://www.etsi.org/deliver/etsi_ts/102900_102999/102991/01.../ts_102991v010301p.pdf)
+
+
+
+## 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                                                                                                                       |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b>                                                        |
+| 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
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@@ -0,0 +1,518 @@
+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.383**
+
+(01/2019)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Digital transmission of television signals - Part 3
+
+---
+
+**Conversion of type length value packet and  
+transport stream for advanced cable  
+transmission systems**
+
+Recommendation ITU-T J.383
+
+
+
+# Recommendation ITU-T J.383
+
+# Conversion of type length value packet and transport stream for advanced cable transmission systems
+
+## Summary
+
+Recommendation ITU-T J.383 describes the conversion schemes of the data structures defined in Recommendation ITU-R BO.2098-0 for cable television systems on the basis of Recommendation ITU-T J.382.
+
+Recommendation ITU-R BO.2098-0 specifies two data structures, MPEG-2 TS and TLV. MPEG-2 TS data packets are directly transmitted while any transmission control signals and service information are transmitted using a descriptor specified in ETSI TS 102 991. TLV packets are not directly transmitted in a TLV format but converted to the GSE 6 packet format specified in Recommendation ITU-T J.382.
+
+The emergency warning system control signal specified in Recommendation ITU-R BO.2098-0 is also converted into physical layer signalling specified in Recommendation ITU-T J.382, to wake up the receiver when the emergency warning system is activated.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T J.383    | 2019-01-13 | 9           | <a href="http://handle.itu.int/11.1002/1000/13836">11.1002/1000/13836</a> |
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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 Definitions .....                                                | 2    |
+| 3.1 Terms defined elsewhere .....                                  | 2    |
+| 3.2 Terms defined in this Recommendation.....                      | 2    |
+| 4 Abbreviations and acronyms .....                                 | 2    |
+| 5 Convention.....                                                  | 2    |
+| 6 System overview.....                                             | 3    |
+| 7 Conversion schemes .....                                         | 3    |
+| 7.1 Transmission of MPEG-2 TS .....                                | 3    |
+| 7.2 Conversion of TLV packets.....                                 | 4    |
+| 7.3 Retransmission of EWS control signal.....                      | 5    |
+| Appendix I – Example of conversion scheme .....                    | 8    |
+| I.1 Conversion of MPEG-2 TS transmission control signal .....      | 8    |
+| I.2 Conversion of TLV service information to LLC GSE packets ..... | 9    |
+
+
+
+# Recommendation ITU-T J.383
+
+## Conversion of type length value packet and transport stream for advanced cable transmission systems
+
+# 1 Scope
+
+The scope of this Recommendation is to define a conversion scheme for type length value (TLV), a data structure specified in [ITU-R BT.1869], and MPEG-2 transport stream (TS) defined in [ITU-R BO.1408-1], for their transmission over cable television systems designed on the basis of [ITU-T J.382].
+
+# 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 J.382] Recommendation ITU-T J.382 (2018), *Advanced digital downstream transmission systems for television, sound and data services for cable distribution*.
+- [ITU-R BO.1408-1] Recommendation ITU-R BO.1408-1 (2002), *Transmission system for advanced multimedia services provided by integrated services digital broadcasting in a broadcasting satellite channel*.
+- [ITU-R BO.2098-0] Recommendation ITU-R BO.2098-0 (2016), *Transmission system for UHDTV satellite broadcasting*.
+- [ITU-R BT.1869] Recommendation ITU-R BT.1869 (2010), *Multiplexing scheme for variable-length packets in digital multimedia broadcasting systems*.
+- [ITU-R BT.2074-1] Recommendation ITU-R BT.2074-1 (2017), *Service configuration, media transport protocol, and signalling information for MMT-based broadcasting systems*.
+- [ETSI EN 302 769] ETSI EN 302 769 V 1.2.1 (2015), *Digital Video Broadcasting (DVB); Frame structure channel coding and modulation for a second generation digital transmission system for cable systems (DVB-C2)*.
+- [ETSI TS 102 606-1] ETSI TS 102 606-1 V1.2.1 (2014), *Digital Video Broadcasting (DVB); Generic Stream Encapsulation (GSE); Part 1: Protocol*.
+- [ETSI TS 102 606-2] ETSI TS 102 606-2 V 1.2.1 (2016), *Digital Video Broadcasting (DVB); Generic Stream Encapsulation (GSE); Part 2: Logical Link Control*.
+- [ETSI TS 102 991] ETSI TS 102 991 V 1.3.1 (2016), *Digital Video Broadcasting (DVB); Implementation Guidelines for a second generation digital cable transmission system (DVB-C2)*.
+
+# **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:
+
+|         |                                                                        |
+|---------|------------------------------------------------------------------------|
+| AMT     | Address Map Table                                                      |
+| DVB-C2  | DVB system for second generation cable transmission                    |
+| EWS     | Emergency Warning System                                               |
+| GSE     | Generic Stream Encapsulation                                           |
+| ISDB-S3 | Integrated Services Digital Broadcasting for Satellite, 3rd generation |
+| LLC     | Logical Link Control                                                   |
+| MPEG-2  | Motion Picture Experts Group version 2                                 |
+| NIT     | Network Information Table                                              |
+| NPD     | Null Packet Deletion                                                   |
+| TLV     | Type Length Value                                                      |
+| TMCC    | Transmission and Multiplexing Configuration Control                    |
+| TS      | Transport Stream                                                       |
+
+# **5 Convention**
+
+In this Recommendation:
+
+The keywords "is required to" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+
+The keywords "is recommended" indicate a requirement which is recommended but which is not absolutely required. Thus this requirement need not be present to claim conformance.
+
+The keywords "is prohibited from" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this document is to be claimed.
+
+The keywords "can optionally" indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the Recommendation.
+
+In the body of this document and its annexes, the words shall, shall not, should, and may sometimes appear, in which case they are to be interpreted, respectively, as is required to, is prohibited from, is recommended, and can optionally. The appearance of such phrases or keywords in an appendix or in material explicitly marked as informative are to be interpreted as having no normative intent.
+
+# 6 System overview
+
+The system overview is shown in Figure 1.
+
+Satellite television systems on the basis of [ITU-R BO.2098-0] support two data structures, MPEG-2 TS and TLV packets. MPEG-2 TS can be directly transmitted over cable television systems on the basis of [ITU-T J.382]. Transport control signals are generated directly in the headend. On the other hand, TLV packets cannot be directly transmitted on the basis of [ITU-T J.382]. Therefore, TLV packets are converted to generic stream encapsulation (GSE) packets and the TLV service information is encapsulated to logical link control (LLC) GSE packets, specified in [ETSI TS 102 606-2].
+
+An EWS control signal in the transmission and multiplexing configuration control (TMCC) signal defined in [ITU-T BO.2098-0], which wakes up the receiver when the EWS is activated, is mapped onto the L1 signalling specified in [ETSI TS 102 991].
+
+![Figure 1 – System overview diagram showing the conversion of ITU-R BO.2098-0 signals to an ITU-T J.382 system via a Headend.](7a0db9703b68b3d06cdaeefc084c0006_img.jpg)
+
+The diagram illustrates the system overview. On the left, a block labeled 'ITU-R BO.2098-0' has three output arrows: 'MPEG-2 TS', 'TLV', and 'TMCC'. The 'MPEG-2 TS' arrow points directly to a block on the right labeled 'ITU-T J.382 system'. The 'TLV' arrow points into a dashed box labeled 'Headend', where it splits into two blocks: 'Conversion of TLV packets' and 'Conversion of TLV service information'. The 'Conversion of TLV packets' block outputs a 'GSE' signal to the 'ITU-T J.382 system'. The 'Conversion of TLV service information' block outputs an 'LLC GSE' signal to the 'ITU-T J.382 system'. The 'TMCC' arrow points into the 'Headend' to a block labeled 'Mapping of EWS control signal', which outputs an 'L1 signalling' signal to the 'ITU-T J.382 system'. Inside the 'Headend', there is also a block labeled 'Generation of transport control signal' which outputs an 'NIT' signal to the 'ITU-T J.382 system'.
+
+Figure 1 – System overview diagram showing the conversion of ITU-R BO.2098-0 signals to an ITU-T J.382 system via a Headend.
+
+J.383(19)\_F01
+
+Figure 1 – System overview
+
+# 7 Conversion schemes
+
+## 7.1 Transmission of MPEG-2 TS
+
+### 7.1.1 Transmission of MPEG-2 TS packets
+
+MPEG-2 TS packets shall be transmitted on the basis of [ITU-T J.382] Appendix I directly without any conversion.
+
+### 7.1.2 Generation of MPEG-2 TS transmission control signals
+
+Transmission control signals for MPEG-2 TS shall be transmitted on the basis of [ITU-T J.382] using the C2\_delivery\_system\_descriptor in the TS loop of the network information table (NIT) descriptor, specified in [ETSI TS 102 991]. The assignment of the descriptor\_tag is 0xF4 as shown in Table 1. The data structure for the C2\_delivery\_system\_descriptor is shown in Figure 2. The descriptor tag extension assigned for this descriptor is 0x00 and other values are reserved for future use.
+
+**Table 1 – Descriptor tag assignment value**
+
+| descriptor_tag | Assignment                    |
+|----------------|-------------------------------|
+| 0xF4           | C2_delivery_system_descriptor |
+
+![Data structure for transmission control signals descriptor diagram showing fields like Description tag, Description length, Description tag extension, PLP ID, Valid symbol length, Guard interval, Bundled channel, Reserved for future use, and a loop containing Data slice ID, Tune Freq., Tune Freq. Type, Outer-code, Modulation, Inner-code, and Reserved for future use. It also includes bit-level details for Description tag extension 0x00.](cfda9df1319e04207eb28bcefd1dab7b_img.jpg)
+
+The diagram illustrates the data structure of the C2\_delivery\_system\_descriptor. It consists of a main descriptor header followed by a loop of system information.
+
+**Descriptor Header:**
+
+| Description tag | Description length | Description tag extension | PLP ID | Valid symbol length | Guard interval | Bundled channel | Reserved for future use |
+|-----------------|--------------------|---------------------------|--------|---------------------|----------------|-----------------|-------------------------|
+| 8               | 8                  | 8                         | 8      | 3                   | 3              | 8               | 2                       |
+| 0xF4            |                    | 0x00                      |        |                     |                |                 |                         |
+
+**Description tag extension 0x00 details:**
+
+- Valid symbol length (3 bits):**
+  - 000 : 448 μs
+  - 001 : 597.33 μs
+  - Other : reserved
+  - 000 : 1/128
+  - 001 : 1/64
+  - Other : reserved
+- Guard interval (3 bits):**
+  - 00 : Centre Freq. to receive data slice
+  - 01 : Centre Freq. for C2 system
+  - 10 : Initial centre Freq. to decode L1
+  - Other : reserved
+
+**Loop (System Information):**
+
+| Data slice ID | Tune Freq. | Tune Freq. Type | Outer-code | Modulation | Inner-code | Reserved for future use |
+|---------------|------------|-----------------|------------|------------|------------|-------------------------|
+| 8             | 32         | 2               | 4          | 8          | 4          | 6                       |
+
+**Loop details:**
+
+- Tune Freq. (32 bits):** Tuning Frequency in Hz
+- Tune Freq. Type (2 bits):**
+  - 00 : Centre Freq. to receive data slice
+  - 01 : Centre Freq. for C2 system
+  - 10 : Initial centre Freq. to decode L1
+  - Other : reserved
+- Outer-code (4 bits):**
+  - 0000 : Undefined
+  - 0001 : No outer-code
+  - 0010 : RS(204, 188)
+  - 0011 : Hxx\_BS system (refer L1 signalling)
+  - Other : reserved
+- Modulation (8 bits):**
+  - 0x00 : Undefined
+  - 0x01 : 16QAM
+  - 0x02 : 32QAM
+  - 0x03 : 64QAM
+  - 0x04 : 128QAM
+  - 0x05 : 256QAM
+  - 0x06 : 1024QAM
+  - 0x80 : Hxx\_BS system (refer L1 signalling)
+  - Other : reserved
+- Inner-code (4 bits):**
+  - 0000 : Undefined
+  - 0001 : code 1/2
+  - 0010 : code 2/3
+  - 0011 : code 3/4
+  - 0100 : code 5/6
+  - 1000 : Hxx\_BS system (refer TMCC signalling)
+  - 1001 : Hxx\_BS system (refer L1 signalling)
+  - Other : reserved
+
+Data structure for transmission control signals descriptor diagram showing fields like Description tag, Description length, Description tag extension, PLP ID, Valid symbol length, Guard interval, Bundled channel, Reserved for future use, and a loop containing Data slice ID, Tune Freq., Tune Freq. Type, Outer-code, Modulation, Inner-code, and Reserved for future use. It also includes bit-level details for Description tag extension 0x00.
+
+J.383(19)\_F02
+
+**Figure 2 – Data structure for transmission control signals descriptor (Descriptor tag extension 0x00)**
+
+## 7.2 Conversion of TLV packets
+
+### 7.2.1 Conversion of TLV packets to GSE packets
+
+TLV packets, except for TLV service information, shall be converted to GSE packets by modifying the packet header and keeping the payload the same. This is more efficient than encapsulating a TLV packet in a GSE packet entirely. The detail of conversion from the TLV packet header to a GSE packet header is shown in Figure 3.
+
+TLV NULL packets shall not be converted to GSE packets. Instead, L1 padding as specified in [ETSI EN 302 769] should be used as necessary.
+
+The GSE profile used shall be decided based on the TLV packet payload size. The signalling of the NPD/GSE-Lite bit within the BBHeader, specified in [ETSI EN 302 769], depends on the GSE profile. The NPD/GSE-Lite bit shall be set equal to one for the GSE-Lite profile. Table 2 defines the relationship between the TLV packet payload size and GSE profile.
+
+![Diagram showing the conversion from a TLV packet to a GSE packet. The TLV header (4 bytes) consists of '01', 'Reserved for future use' (1 byte), 'Packet type' (1 byte), and 'Data length' (2 bytes). The 'Reserved for future use' field is marked 'Do not retransmit'. The Packet type and Data length fields are mapped to the GSE header. The GSE header (8 bytes) consists of 'S' (1 bit), 'E' (1 bit), 'LT' (1 bit), 'GSE length' (12 bits), 'Fragment ID' (1 byte), 'Total length' (2 bytes), and 'Protocol type' (2 bytes). The Packet type is mapped to the GSE length field, and the Data length is mapped to the Total length field. A table on the right shows the mapping of TLV packet types to GSE protocol types.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg)
+
+| TLV packet type                          | GSE protocol type   |
+|------------------------------------------|---------------------|
+| 0x01 (IPv4 packet)                       | 0x0800              |
+| 0x02 (IPv6 packet)                       | 0x86DD              |
+| 0x03 (IP packet with header compression) | 0x22F2              |
+| 0xFE (Signalling packet)                 | 0x0087              |
+| 0xFF (NULL packet)                       | (Do not retransmit) |
+| Other                                    | undefined           |
+
+Diagram showing the conversion from a TLV packet to a GSE packet. The TLV header (4 bytes) consists of '01', 'Reserved for future use' (1 byte), 'Packet type' (1 byte), and 'Data length' (2 bytes). The 'Reserved for future use' field is marked 'Do not retransmit'. The Packet type and Data length fields are mapped to the GSE header. The GSE header (8 bytes) consists of 'S' (1 bit), 'E' (1 bit), 'LT' (1 bit), 'GSE length' (12 bits), 'Fragment ID' (1 byte), 'Total length' (2 bytes), and 'Protocol type' (2 bytes). The Packet type is mapped to the GSE length field, and the Data length is mapped to the Total length field. A table on the right shows the mapping of TLV packet types to GSE protocol types.
+
+Figure 3 – Conversion from TLV packet to GSE packet
+
+Table 2 – Relationship between TLV payload size and GSE profile
+
+| TLV payload size     | GSE profile                 |
+|----------------------|-----------------------------|
+| Less than 1800 bytes | GSE-Lite                    |
+| Less than 4093 bytes | GSE (without fragmentation) |
+| More than 4094 bytes | GSE (fragmentation)         |
+
+### 7.2.2 Conversion of TLV service information to LLC GSE packets
+
+TLV service information shall be converted to LLC GSE packets, specified in [ETSI TS 102 606-2], with protocol type 0x0087. LLC GSE packets are GSE packets which contain signalling and transmission control signals. Particularly note that TLV-NIT and AMT packets shall be converted to GSE tables with table\_id 0xC0 and 0xC1 within the LLC GSE packet. The data structure for TLV-NIT and AMT tables, specified in [ITU-R BT.2074-0], are stored into table\_content\_byte. An index which gathers the table information in a packet is added to the beginning of the table. The LLC index table\_id value used is 0xB3.
+
+## 7.3 Retransmission of EWS control signal
+
+The EWS control signal is transmitted in the transmit/receive control information in the TMCC, specified in [ITU-R BO.2098-0]. Figure 4 shows the structure of TMCC, which contains the transmit/receive control information.
+
+| Order of change | Transmission mode/slot information | Stream type/relative number information | Packet format/relative stream number information | Relative stream number/slot information | Corresponding table between relative stream ID and transmission stream ID | Transmit/receive control information | Extension information |
+|-----------------|------------------------------------|-----------------------------------------|--------------------------------------------------|-----------------------------------------|---------------------------------------------------------------------------|--------------------------------------|-----------------------|
+| 8 bits          | 192 bits                           | 128 bits                                | 3 840 bits                                       | 480 bits                                | 256 bits                                                                  | 8 bits                               | 3 614 bits            |
+
+Figure 4 – Bit configuration of TMCC signal
+
+Figure 5 shows the structure of the transmit/receive control information. The first 1 bit is assigned as the EWS control signal.
+
+|                                                                         |                                                      |                                |                               |          |
+|-------------------------------------------------------------------------|------------------------------------------------------|--------------------------------|-------------------------------|----------|
+| IRD activation control signal for emergency warning broadcasting system | Frame indicator for up-link site diversity operation | Main up-link station indicator | Sub up-link station indicator | Reserved |
+| 1 bit                                                                   | 1 bit                                                | 1 bit                          | 1 bit                         | 4 bits   |
+
+J.383(19)\_F05
+
+**Figure 5 – Bit configuration of transmit/receive control information in the TMCC signal**
+
+Table 3 shows the structure of the L1 signalling part 2 data, specified in [ETSI EN 302 769]. The 1 bit EARLY\_WARNING\_SYSTEM (EWS) is used to retransmit the EWS control signal.
+
+**Table 3 – The signalling fields of L1 signalling part 2 data**
+
+| Field                       | Size (bits) |
+|-----------------------------|-------------|
+| NETWORK_ID                  | 16          |
+| C2_SYSTEM_ID                | 16          |
+| START_FREQUENCY             | 24          |
+| C2_BANDWIDTH                | 16          |
+| GUARD_INTERVAL              | 2           |
+| C2_FRAME_LENGTH             | 10          |
+| L1_PART2_CHANGE_COUNTER     | 8           |
+| NUM_DSLICE                  | 8           |
+| NUM_NOTCH                   | 4           |
+| for i=0..NUM_DSLICE-1 {     |             |
+| DSLICE_ID                   | 8           |
+| DSLICE_TUNE_POS             | 14 or 13    |
+| DSLICE_OFFSET_LEFT          | 9 or 8      |
+| DSLICE_OFFSET_RIGHT         | 9 or 8      |
+| DSLICE_TI_DEPTH             | 2           |
+| DSLICE_TYPE                 | 1           |
+| if(DSLICE_TYPE=='1' {       |             |
+| FEC_HEADER_TYPE             | 1           |
+| }                           |             |
+| DSLICE_CONST_CONF           | 1           |
+| DSLICE_LEFT_NOTCH           | 1           |
+| DSLICE_NUM_PLP              | 8           |
+| for i=0..DSLICE_NUM_PLP-1 { |             |
+| PLD_ID                      | 8           |
+| PLP_BUNLED                  | 1           |
+| PLP_TYPE                    | 2           |
+| PLP_PAYLOAD_TYPE            | 5           |
+| if PLP_TYPE=='00' or '01' { |             |
+| PLP_GROUP_ID                | 8           |
+| }                           |             |
+| }                           |             |
+| }                           |             |
+
+**Table 3 – The signalling fields of L1 signalling part 2 data**
+
+| Field                          | Size (bits) |
+|--------------------------------|-------------|
+| if DSLICE_TYPE=='0' {          |             |
+| PLP_START                      | 14          |
+| PLP_FEC_TYPE                   | 1           |
+| PLP_MOD                        | 3           |
+| PLP_COD                        | 3           |
+| }                              |             |
+| PSI/SI_REPROCESSING            | 1           |
+| if (PSI/SI_REPROCESSING=='0' { |             |
+| transport_stream_id            | 16          |
+| original_network_id            | 16          |
+| }                              |             |
+| RESERVED_1                     |             |
+| }                              |             |
+| RESERVED_2                     |             |
+| }                              |             |
+| for i=0..NUM_NOTCH-1 {         |             |
+| NOTCH_START                    | 14 or 13    |
+| NOTCH_WIDTH                    | 9 or 8      |
+| RESERVED_3                     | 8           |
+| }                              |             |
+| RESERVED_TONE                  | 1           |
+| EARLY_WARNING_SYSTEM (EWS)     | 1           |
+| C2_VERSION                     | 4           |
+| RESERVED_4                     | 11          |
+
+## Appendix I
+
+## Example of conversion scheme
+
+(This appendix does not form an integral part of this Recommendation.)
+
+### I.1 Conversion of MPEG-2 TS transmission control signal
+
+Conversion of the MPEG-2 TS transmission control signal to the C2\_delivery\_system\_descriptor is shown in Table I.1.
+
+**Table I.1 – Data syntax for transmission control signals (Descriptor tag extension 0x00)**
+
+| Syntax                            | No. of bits | Value  | Remarks                                                                                                                                                                                                                                                                            |
+|-----------------------------------|-------------|--------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| C2_delivery_system_descriptor (){ |             |        |                                                                                                                                                                                                                                                                                    |
+| descriptor_tag                    | 8           | 0xF4   |                                                                                                                                                                                                                                                                                    |
+| descriptor_length                 | 8           | –      |                                                                                                                                                                                                                                                                                    |
+| descriptor_tag_extension          | 8           | 0x00   |                                                                                                                                                                                                                                                                                    |
+| plp_id                            | 8           | –      |                                                                                                                                                                                                                                                                                    |
+| active_OFDM_symbol_duration       | 3           | '000'  | 000 : 448 us<br>001 : 597.33 us<br>Other : Reserved                                                                                                                                                                                                                                |
+| guard_interval                    | 3           | '000'  | 000 : 1/128<br>001 : 1/64<br>Other : Reserved                                                                                                                                                                                                                                      |
+| bundled_channel                   | 8           | –      |                                                                                                                                                                                                                                                                                    |
+| reserved_for_future_use           | 2           | 0x3    | undefined                                                                                                                                                                                                                                                                          |
+| for ( i = 0; i < N; ++ i ) {      |             |        |                                                                                                                                                                                                                                                                                    |
+| data_slice_id                     | 8           | –      |                                                                                                                                                                                                                                                                                    |
+| C2_tuning_frequency               | 32          | –      | Specify tuning frequency based on Tune Freq type (in Hz)                                                                                                                                                                                                                           |
+| C2_tuning_frequency_type          | 2           | '00'   | 00 : Centre frequency to receive Data Slice<br>01 : Centre frequency for C2 system<br>10 : Initial centre frequency to decode L1 when Data Slice cannot decode L1<br>Other: Reserved                                                                                               |
+| outer_code                        | 4           | '0011' | 0000 : Undefined<br>0001 : No Outer Code<br>0010 : RS(204, 188)<br>0011 : J.382 (refer L1 transmission control signals)                                                                                                                                                            |
+| modulation                        | 8           | 0x01   | 0x00 : Undefined<br>0x01 : 16QAM    0x04 : 128QAM<br>0x02 : 32QAM    0x05 : 256QAM<br>0x03 : 64QAM    0x07 : 1024QAM<br>0x80 : J.382 (refer L1 transmission control signals)                                                                                                       |
+| inner_code                        | 4           | '1001' | 0000 : Undefined    0011 : code rate 3/4<br>0001 : code rate 1/2    0100 : code rate 5/6<br>0010 : code rate 2/3    0101 : code rate 7/8<br>1000 : ISDB-S (refer TMCC signal)<br>1001 : J.382 (refer L1 transmission control signals)<br>1111 : No inner code<br>Other : Undefined |
+| reserved_for_future_use           | 6           | 0x3f   |                                                                                                                                                                                                                                                                                    |
+| }                                 |             |        |                                                                                                                                                                                                                                                                                    |
+
+### I.2 Conversion of TLV service information to LLC GSE packets
+
+Conversion of TLV service information to an LLC GSE packet is shown in Table I.2. An LLC GSE packet shall contain either or both TLV-NIT and AMT packet information.
+
+**Table I.2 – GSE packet structure when converting TLV service information to an LLC GSE packet**
+
+| Syntax                      | No. of bits | Value  | Remarks                    |
+|-----------------------------|-------------|--------|----------------------------|
+| GSE_Packet() {              |             |        |                            |
+| Start_Indicator             | 1           | 1      | Complete packet            |
+| End_Indicator               | 1           | 1      | Complete packet            |
+| Label_Type_Indicator        | 2           | '10'   | Broadcast (no label field) |
+| GSE_Length                  | 12          | –      |                            |
+| Protocol_Type               | 16          | 0x0087 | GSE Signalling packet      |
+| gse_table_structure() {     |             |        | Start Index                |
+| table_id                    | 8           | 0xB3   | LLC index                  |
+| interactive_network_id      | 16          | –      | Network ID                 |
+| Reserved                    | 2           | '11'   | Reserved                   |
+| version_number              | 5           | 1      | Version 1                  |
+| current_next_indicator      | 1           | 1      | Valid                      |
+| for (i=0; i<N; i++) {       |             |        |                            |
+| LLC_index {                 |             |        | Each table index           |
+| num_table_entries           | 8           | 2      | TLV-NIT and AMT            |
+| table_id                    | 8           | 0xC0   | TLV_NIT                    |
+| Reserved                    | 2           | '11'   | Reserved                   |
+| version                     | 5           | 1      | Version 1                  |
+| current_next_indicator      | 1           | 1      | Valid                      |
+| offset                      | 32          | –      |                            |
+| table_id                    | 8           | 0xC1   | AMT                        |
+| reserved                    | 2           | '11'   | Reserved                   |
+| version                     | 5           | 1      | Version 1                  |
+| current_next_indicator      | 1           | 1      | Valid                      |
+| offset                      | 32          | –      |                            |
+| } /* LLC_index */           |             |        |                            |
+| }                           |             |        |                            |
+| } /* gse_table_structure */ |             |        | End Index                  |
+| gse_table_structure() {     |             |        | Start Table 0              |
+| table_id                    | 8           | 0xC0   | TLV_NIT                    |
+| interactive_network_id      | 16          | –      | Network ID                 |
+| Reserved                    | 2           | '11'   | Reserved                   |
+| version_number              | 5           | 1      | Version 1                  |
+| current_next_indicator      | 1           | 1      | Valid                      |
+
+**Table I.2 – GSE packet structure when converting TLV service information to an LLC GSE packet**
+
+| Syntax                                                            | No. of bits | Value | Remarks       |
+|-------------------------------------------------------------------|-------------|-------|---------------|
+| for (i=0; i<N; i++) {<br>/* TLV_Network_Information_Table */<br>} |             |       | TLV-NIT       |
+| } /* gse_table_structure */                                       |             |       | End Table 0   |
+| gse_table_structure() {                                           |             |       | Start Table 1 |
+| table_id                                                          | 8           | 0xC1  | AMT           |
+| interactive_network_id                                            | 16          |       | Network ID    |
+| Reserved                                                          | 2           | '11'  | Reserved      |
+| version_number                                                    | 5           | 1     | Version 1     |
+| current_next_indicator                                            | 1           | 1     | Valid         |
+| for (i=0; i<N; i++) {<br>/* Address_Map_Table */<br>}             |             |       | AMT           |
+| } /* gse_table_structure */                                       |             |       | End Table 1   |
+| } /* GSE packet */                                                |             |       |               |
+
+
+
+## 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                                                                                                                       |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b>                                                        |
+| 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/J/T-REC-J.460.2-200806-I_PDF-E/raw.md b/marked/J/T-REC-J.460.2-200806-I_PDF-E/raw.md
new file mode 100644
index 0000000000000000000000000000000000000000..833087a48d1dd29a44304e6f8b2c5bab2e975288
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+++ b/marked/J/T-REC-J.460.2-200806-I_PDF-E/raw.md
@@ -0,0 +1,1045 @@
+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.460.2**
+
+(06/2008)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+---
+
+**IP Cablecom2 residential SIP telephony:  
+embedded digital voice adapter (E-DVA)  
+specification**
+
+Recommendation ITU-T J.460.2
+
+
+
+# **Recommendation ITU-T J.460.2**
+
+# **IPCablecom2 residential SIP telephony: embedded digital voice adapter (E-DVA) specification**
+
+## **Summary**
+
+Recommendation ITU-T J.460.2 defines the embedded Digital Voice Adaptor (E-DVA) requirements for the analog interface and for powering of the E-DVA. An embedded DVA is a DOCSIS cable modem (CM) integrated with an IPCablecom2 DVA. These requirements enable a sufficiently reliable service to meet assumed consumer expectations related to residential telephony.
+
+## **Source**
+
+Recommendation ITU-T J.460.2 was approved on 13 June 2008 by ITU-T Study Group 9 (2005-2008) under 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 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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  |
+| 2.1        | Normative References .....                         | 1  |
+| 2.2        | Informative References .....                       | 2  |
+| 2.3        | Reference Acquisition .....                        | 2  |
+| 3          | Terms and Definitions .....                        | 2  |
+| 4          | Abbreviations, acronyms and conventions .....      | 3  |
+| 4.1        | Abbreviations and Acronyms .....                   | 3  |
+| 4.2        | Conventions .....                                  | 4  |
+| 5          | Overview .....                                     | 4  |
+| 5.1        | IPCablecom2 Overview.....                          | 4  |
+| 5.2        | Service Goals.....                                 | 4  |
+| 5.3        | IPCablecom2 Reference Architecture .....           | 5  |
+| 5.4        | Embedded Digital Voice Adaptor .....               | 5  |
+| 6          | E-DVA power requirements .....                     | 5  |
+| 6.1        | Power Considerations.....                          | 6  |
+| 6.2        | Typical E-DVA Traffic Model.....                   | 6  |
+| 6.3        | Service Requirements Under AC Fail Conditions..... | 6  |
+| 6.4        | Local Powering with Battery Backup.....            | 6  |
+| 7          | E-DVA analog port requirements.....                | 6  |
+| 8          | Client requirement .....                           | 6  |
+| 8.1        | Provisioning.....                                  | 6  |
+| 8.2        | Security .....                                     | 7  |
+| 8.3        | NAT/Firewall Traversal .....                       | 7  |
+| 8.4        | Codecs .....                                       | 7  |
+| 8.5        | Loopback Test Capability.....                      | 8  |
+| 9          | E-DVA Monitoring requirements.....                 | 9  |
+| 9.1        | eCM Monitoring.....                                | 10 |
+| 9.2        | E-DVA Monitoring .....                             | 10 |
+| 9.3        | Battery-Backup Monitoring.....                     | 10 |
+| Appendix I | – Example of a power calculation.....              | 12 |
+| I.1        | Loop Start Signaling.....                          | 14 |
+| I.2        | General Supervision .....                          | 15 |
+| I.3        | General Ringing.....                               | 17 |
+| I.4        | Voice Grade Analog Transmission .....              | 18 |
+| I.5        | Out of Service Requirements.....                   | 22 |
+| I.6        | Message Waiting Indicator.....                     | 24 |
+
+
+
+# IPCablecom2 residential SIP telephony: embedded digital voice adapter (E-DVA) specification
+
+# 1 Scope
+
+This Recommendation defines the embedded Digital Voice Adaptor (E-DVA) requirements for the analog interface and for powering of the E-DVA. An embedded DVA is a DOCSIS cable modem (CM) integrated with an IPCablecom2 DVA.
+
+The purpose of this Recommendation is to define a set of requirements that will enable a sufficiently reliable service to meet assumed consumer expectations related to residential telephony. These assumed expectations include constant availability, including availability during power failure at the customer's premises, and access to emergency services (e.g., 121 or 911).
+
+It is an important objective of this work that interoperability between IPCablecom 2.0 and 3GPP IMS is provided. IPCablecom 2.0 is based upon 3GPP IMS, but includes additional functionality necessary to meet the requirements of cable operators. Recognizing developing converged solutions for wireless, wireline, and cable, it is expected that further development of IPCablecom 2.0 will continue to monitor and contribute to IMS developments in 3GPP, with the aim of alignment of 3GPP IMS and IPCablecom 2.0.
+
+NOTE – The structure and content of this Recommendation have been organized for ease of use by those familiar with the original source material; as such, the usual style of ITU-T recommendations has not been applied.
+
+# 2 References
+
+## 2.1 Normative 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.
+
+- [CODEC-MEDIA] Recommendation ITU-T J.361 (2006), *IPCablecom2 Codec Media*.
+- [DOCSIS OSSIV2.0] ANSI/SCTE 79-2 2002, *DOCS 2.0 Operations Support System Interface*.
+- [DOCSIS RFIV2.0] Recommendation ITU-T J.122 (2002), *Second-generation transmission systems for interactive cable television services – IP cable modems*.
+- [eDOCSIS] Recommendation ITU-T J.126 (2007), *Embedded Cable Modem device specification*.
+- [G.168] Recommendation ITU-T G.168 (2004), *Digital network echo cancellers*.
+- [G.711] Recommendation ITU-T G.711 (1988), *Pulse code modulation (PCM) of voice frequencies*.
+- [PKT 23.228] Recommendation ITU-T J.366.3 (Draft), *IPCablecom2 IP Multimedia Subsystem Stage 2 (3GPP TS 23.228)*.
+- [PKT 24.229] Recommendation ITU-T J.366.4 (Draft), *IPCablecom2 SIP and SDP Stage 3 (3GPP TS 24.229)*.
+
+|                 |                                                                                                                   |
+|-----------------|-------------------------------------------------------------------------------------------------------------------|
+| [PKT 33.203]    | Recommendation ITU-T J.366.7 (Draft), <i>IPCablecom2 Access Security for IP-Based Services (3GPP TS 33.203)</i> . |
+| [RFC 4330]      | IETF RFC 4330, <i>Simple Network Time Protocol version 4 for IPv6, IPv4, and OSI</i> , January, 2006.             |
+| [RSTF]          | Recommendation ITU-T J.460.1, <i>IPCablecom2 Residential SIP Telephony Feature Specification</i> .                |
+| [SEC1.5]        | Recommendation ITU-T J.170, <i>IPCablecom security specification</i> .                                            |
+| [RST E-UE Prov] | Recommendation ITU-T J.460.4 (draft) – <i>IPCablecom2 RST E-UE Provisioning Specification</i> .                   |
+
+## 2.2 Informative References
+
+This Recommendation uses the following informative references.
+
+|                      |                                                                                                                                                                                                                                                                                            |
+|----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| [ARCH-FRM TR]        | Recommendation ITU-T J.360, <i>IPCablecom2 Architecture Framework</i> .                                                                                                                                                                                                                    |
+| [ID MMUSIC LOOPBACK] | IETF Internet Draft, <i>An Extension to the Session Description Protocol (SDP) for Media Loopback</i> , draft-ietf-mmusic-media-loopback-04.txt, August 2006, <i>work in progress</i> .                                                                                                    |
+| [ID SIP ANSWERMODE]  | IETF Internet Draft, <i>Requesting Answering Modes for the Session Initiation Protocol (SIP)</i> , draft-ietf-sip-answermode-01, April 2006, <i>work in progress</i> .                                                                                                                     |
+| [Key Smith]          | P. Key and D. Smith (editors). 1999. <i>The Internet &amp; The Public Switched Telephone Network – A Troubled Marriage. In Teletraffic Engineering in a Competitive World</i> . Edinberg: Elsevier.                                                                                        |
+| [NFT TR]             | Recommendation ITU-T J.360, <i>IPCablecom2 Architecture Framework Appendix V NAT and Firewall Traversal</i> .                                                                                                                                                                              |
+| [V.25]               | Recommendation ITU-T V.25 (1996), <i>Automatic answering equipment and general procedures for automatic calling equipment on the general switched telephone network including procedures for disabling of echo control devices for both manually and automatically established calls</i> . |
+
+## 2.3 Reference Acquisition
+
+- IHS Standards Store, Internet: <http://global.ihs.com/>
+- Internet Engineering Task Force (IETF), Internet: <http://www.ietf.org/>
+
+NOTE – Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time.
+
+The list of current Internet-Drafts can be accessed at <http://www.ietf.org/ietf/1id-abstracts.txt>.
+
+# 3 Terms and Definitions
+
+This Recommendation defines the following terms:
+
+**3.1 customer premises equipment:** Usage of CPE within this Recommendation generically refers to the cable modem and E-DVA device that resides at the subscriber home, as well as any customer telephony equipment (telephones, answering machines, fax machines, etc.). Typically, CPE would refer to equipment that is beyond the service provider network interface, such as a
+
+telephone or personal computer. However, since the cable modem and E-DVA represent the service provider network interface device at the subscriber home, it is commonly referred to as CPE.
+
+**3.2 hybrid fibre coax:** Access network architecture consisting of fibre-optic feeders from the head end to nodes, at which point a coaxial cable is used for the final distribution to the subscribers.
+
+**3.3 uninterruptible power supply:** A power supply including a battery for backup power when AC input power fails.
+
+# **4 Abbreviations, acronyms and conventions**
+
+## **4.1 Abbreviations and Acronyms**
+
+This Recommendation uses the following abbreviations:
+
+|          |                                                                                   |
+|----------|-----------------------------------------------------------------------------------|
+| A/D      | Analog to Digital converter                                                       |
+| CCS      | One Hundred Call Seconds                                                          |
+| CM       | Cable Modem                                                                       |
+| CMS      | Call Management Server                                                            |
+| CMTS     | Cable Modem Termination System                                                    |
+| CPE      | Customer Premises Equipment                                                       |
+| CSCF     | Call Session Control Function                                                     |
+| D/A      | Digital to Analog converter                                                       |
+| DOCSIS®  | Data-Over-Cable System Interface Specifications                                   |
+| DTMF     | Dual Tone Multi Frequency                                                         |
+| DVA      | Digital Voice Adaptor                                                             |
+| eCM      | Embedded Cable Modem                                                              |
+| eDOCSIS™ | Embedded Data-Over-Cable System Interface Specification                           |
+| E-DVA    | Embedded Digital Voice Adaptor                                                    |
+| FITL     | Fibre In The Loop. A PSTN architecture consisting of a fibre-optic access network |
+| HFC      | Hybrid Fibre Coax                                                                 |
+| IP       | Internet Protocol. A network layer protocol                                       |
+| LEC      | Local Exchange Carrier                                                            |
+| NAT      | Network Address Translation                                                       |
+| NCS      | Network Call Signalling                                                           |
+| OSSI     | Operations Support System Interface                                               |
+| POTS     | Plain Old Telephone Service                                                       |
+| PSTN     | Public Switched Telephone Network                                                 |
+| RST      | Residential SIP Telephony                                                         |
+| RTCP     | Real Time Control Protocol                                                        |
+| RTCP XR  | Real Time Control Protocol Extended Reports                                       |
+| SDP      | Session Description Protocol                                                      |
+
+|      |                                                                                      |
+|------|--------------------------------------------------------------------------------------|
+| SIP  | Session Initiation Protocol                                                          |
+| STUN | Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators |
+| UDP  | User Datagram Protocol                                                               |
+| UPS  | Uninterruptible Power Supply                                                         |
+
+## 4.2 Conventions
+
+Throughout this Recommendation, the words that are used to define the significance of particular requirements are capitalized. These words are:
+
+|              |                                                                                                                                                                                                                                                                                     |
+|--------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| "MUST"       | This word means that the item is an absolute requirement of this Recommendation.                                                                                                                                                                                                    |
+| "MUST NOT"   | This phrase means that the item is an absolute prohibition of this Recommendation.                                                                                                                                                                                                  |
+| "SHOULD"     | This word means that there may exist valid reasons in particular circumstances to ignore this item, but the full implications should be understood and the case carefully weighed before choosing a different course.                                                               |
+| "SHOULD NOT" | This phrase means that there may exist valid reasons in particular circumstances when the listed behaviour is acceptable or even useful, but the full implications should be understood and the case carefully weighed before implementing any behaviour described with this label. |
+| "MAY"        | This word means that this item is truly optional. One vendor may choose to include the item because a particular marketplace requires it or because it enhances the product, for example; another vendor may omit the same item.                                                    |
+
+# 5 Overview
+
+## 5.1 IPCablecom2 Overview
+
+The IPCablecom2 project is aimed at defining interface Recommendations that can be used to develop interoperable equipment capable of providing packet-based voice, video, and other high-speed multimedia services over hybrid fibre coax (HFC) cable systems utilizing the Data-Over-Cable Interface Specification [DOCSIS RFIV2.0].
+
+## 5.2 Service Goals
+
+One application of the IPCablecom2 architecture is packet-based voice communications for cable system subscribers. The IPCablecom2 architecture as a whole enables voice communications, video, and data services based on bidirectional transfer of Internet Protocol (IP) traffic between the cable system headend and customer locations, over an all-coaxial or HFC cable network as shown in simplified form in Figure 1.
+
+![Diagram of Telephony Services Over the Data-Over-Cable System architecture.](1eadbbe42cfcac5c0023577110aec5e3_img.jpg)
+
+```
+
+graph LR
+    WAN((Wide Area Network)) <--> CMTS[CMTS]
+    CMTS <--> CN((Cable Network))
+    CN <--> E-DVA[E-DVA]
+    E-DVA <--> Phone[Phone]
+    E-DVA <--> Laptop[Laptop]
+  
+```
+
+The diagram illustrates the flow of data and services in an IPCablecom2 system. It starts with a cloud labeled 'Wide Area Network' connected via a bidirectional arrow to a 'CMTS' (Cable Modem Termination System) icon. The 'CMTS' is connected via a bidirectional arrow to a cloud labeled 'Cable Network'. The 'Cable Network' is connected via a bidirectional arrow to an 'E-DVA' (Ethernet Device) box. From the 'E-DVA', two bidirectional arrows lead to a telephone icon and a laptop icon, representing voice and data services respectively.
+
+Diagram of Telephony Services Over the Data-Over-Cable System architecture.
+
+Figure 1 – Telephony Services Over the Data-Over-Cable System
+
+The transmission path over the cable system is realized by a cable modem termination system (CMTS) and at each customer location by a cable modem (CM). The E-DVA includes an embedded cable modem and a Residential SIP Telephony (RST) client and analog ports for telephone devices. The E-DVA may include digital ports. The conversion between digital RST signaling and voice to analog telephone interfaces is accomplished within the E-DVA.
+
+## 5.3 IPCablecom2 Reference Architecture
+
+For a description of the IPCablecom2 architecture and Functional Components, please refer to [ARCH-FRM TR].
+
+## 5.4 Embedded Digital Voice Adaptor
+
+A Digital Voice Adaptor (DVA) is an IPCablecom2 client device that contains a subscriber-side interface to the subscriber's CPE (e.g., telephone) and a network-side signaling interface to call control elements in the network (e.g., P-CSCF, S-CSCF, Application servers, etc.). A DVA provides codecs and all signaling and encapsulation functions required for media transport and call signaling.
+
+DVAs reside at the customer side and are connected to other IPCablecom2 network elements via the HFC access network (DOCSIS). IPCablecom2 DVAs are required to support the SIP protocol as specified in IPCablecom2 Recommendation [RSTF].
+
+IPCablecom2 only defines support for an embedded DVA (E-DVA). An E-DVA is a single hardware device that incorporates a DOCSIS 1.1 or higher CM as well as an IPCablecom2 DVA component. Figure 2 shows a representative functional diagram of an E-DVA. Additional E-DVA functionality is further defined in [ARCH-FRM TR]. For the purposes of this Recommendation, DVA is interpreted to be identical to E-DVA.
+
+![Figure 2 – E-DVA Protocols. A block diagram showing the protocol stack for an E-DVA. At the top are 'Network interface (Ethernet)' and 'Telephone interfaces (RJ11)'. Below these is a layer containing 'DOCSIS bridge', 'DVA application (RST)', and 'XCAP'. The next layer contains 'SNMP/DHCP/...', 'RTP/RTCP', 'SIP', 'HTTP', and 'TLS'. Below that is a layer with 'UDP' and 'TCP'. The next layer is 'IP, IPsec, UDP encapsulated IPsec'. Below that is 'DOCSIS MAC', and at the bottom is 'DOCSIS PHYSICAL LAYER'. A 'DOCSIS FILTER' block is shown on the left, spanning the layers from 'DOCSIS bridge' down to 'IP, IPsec, UDP encapsulated IPsec'.](8e14350b4b669119a3bdfca7869110ca_img.jpg)
+
+Figure 2 – E-DVA Protocols. A block diagram showing the protocol stack for an E-DVA. At the top are 'Network interface (Ethernet)' and 'Telephone interfaces (RJ11)'. Below these is a layer containing 'DOCSIS bridge', 'DVA application (RST)', and 'XCAP'. The next layer contains 'SNMP/DHCP/...', 'RTP/RTCP', 'SIP', 'HTTP', and 'TLS'. Below that is a layer with 'UDP' and 'TCP'. The next layer is 'IP, IPsec, UDP encapsulated IPsec'. Below that is 'DOCSIS MAC', and at the bottom is 'DOCSIS PHYSICAL LAYER'. A 'DOCSIS FILTER' block is shown on the left, spanning the layers from 'DOCSIS bridge' down to 'IP, IPsec, UDP encapsulated IPsec'.
+
+J.460.2(08)\_F02
+
+**Figure 2 – E-DVA Protocols**
+
+# 6 E-DVA power requirements
+
+This clause defines the power requirements of the E-DVA. This includes power consumption and presents associated traffic models recommended for power consumption calculations.
+
+## **6.1 Power Considerations**
+
+Local power refers to utilizing the subscriber's home AC utility power as the supply for the E-DVA. A battery backup is utilized to provide telephony services when the utility power fails.
+
+## **6.2 Typical E-DVA Traffic Model**
+
+In order to properly dimension the power equipment, it is necessary to calculate long-term average power usage. Since these are likely to vary considerably from location to location, it is impossible to have a single answer. One method to estimate the average long-term power requirements is described in Appendix I.
+
+## **6.3 Service Requirements Under AC Fail Conditions**
+
+The E-DVA MUST remain operational during the switch between AC outage to battery backup. The E-DVA MUST also maintain provisioned services (operational means capable of originating calls, ringing, and terminating calls, if provisioned as in-service). When in battery mode, services will be offered as configured by the operator. This configuration may be different from the services when provided with AC power. The E-DVA MUST maintain established telephony calls across the switchover between AC power and battery backup. Since data traffic is not required for an IPCablecom2 service, the E-DVA data service MAY be de-activated immediately under local AC power fail conditions.
+
+## **6.4 Local Powering with Battery Backup**
+
+Local powering is accomplished utilizing a UPS that converts household AC power to DC power for the E-DVA. The UPS also provides battery backup to bridge E-DVA operation through typical local power outages. In addition, telemetry signals provide remote monitoring capability for local AC power and battery conditions. The indoor climate controlled environment is typically desired for battery placement to maximize battery life. E-DVAs MAY include an embedded UPS or utilize an external UPS.
+
+# **7 E-DVA analog port requirements**
+
+The E-DVA analog port represents an interface between the IPCablecom2/DOCSIS/IP (Internet protocol) network and devices designed to function when connected to the PSTN using standard PSTN interfaces. The subscriber side of this interface is an analog interface consistent with the PSTN, and the network side of this interface is a digital interface to the IP-based IPCablecom2 network, which rides on top of the DOCSIS transport. It is expected that many operators will choose to use the IPCablecom2 architecture to offer services to customers in residential dwellings. In such applications, the E-DVA will reside at the subscriber premises, typically as an interior unit with battery backup. Finally, because the network side of the port interface is digital, and the device resides close to the subscriber, the analog subscriber side of the port interface will only be required to support relatively short metallic (copper twisted pair) drops (i.e., 150 metres).
+
+Since there are many different analog port specifications in use throughout the world, this Recommendation will not specify one. The E-DVA MUST have an analog port that conforms to appropriate National practices. An example of such a port is given in Appendix I.
+
+# **8 Client requirement**
+
+## **8.1 Provisioning**
+
+The E-DVA MUST comply with the E-DVA provisioning requirements as specified in [RST E-UE-Prov].
+
+## 8.2 Security
+
+The security considerations for the E-DVA are based on those specified in [PKT 33.203], [PKT 23.228], [PKT 24.229], and [NFT TR]. The requirements specific to the E-DVA are provided below.
+
+### 8.2.1 Authentication
+
+As part of the SIP registration for each provisioned line, the E-DVA MUST support SIP-Digest-based authentication with the IPCablecom2 core network as detailed in [PKT 33.203] and [PKT 24.229], using the corresponding Private User Identity/Public User Identity pair and the User ID/Password pair obtained from the Authentication server during the bootstrapping process. The registration also allows the E-DVA to establish any necessary security associations for the SIP signaling security with the P-CSCF, as specified in [PKT 33.203].
+
+The E-DVA MAY support any other authentication procedure described in [PKT 33.203].
+
+### 8.2.2 Signaling Security
+
+The E-DVA MUST support TLS for the SIP-signaling security.
+
+The E-DVA MAY support other signaling-security protocols specified in [PKT 33.203].
+
+For both authentication and signaling security the E-DVA MUST use the X.509v3 certificate profile as follows.
+
+E-DVA certificates MUST follow the MTA Device certificate profile specified in [SEC1.5]. Existing IPCablecom certificates are being reused for IPCablecom2 Release 2.0. E-DVA certificates MUST be issued by MTA Manufacturer Certificate Authorities as specified in [SEC1.5].
+
+In order to perform authentication for secure configuration, the E-DVA MUST possess the CableLabs Service Provider Root CA certificate. This certificate is installed into each E-DVA at the time of manufacture or with a secure software download as specified in [SEC1.5] and MUST NOT be updated by the provisioning server.
+
+## 8.3 NAT/Firewall Traversal
+
+Even though there is no NAT/Firewall between the E-DVA and the CMTS, there may be a network-based NAT/Firewall behind the CMTS.
+
+The NAT/Firewall traversal requirements described in [PKT 23.228], [PKT 24.229], and [NFT TR] SHOULD be supported by the E-DVA.
+
+## 8.4 Codecs
+
+G.711  $\mu$ -law, G.711 A-law [G.711], T.38, V.152, and DTMF Relay MUST be supported by the E-DVA per the [CODEC-MEDIA] Recommendation. Both  $\mu$ -law and A-law MUST be offered at session establishment if G.711 is offered. The packet period of a G.711 payload is configured as shown in Table 1. The offering of T.38, V.152, and DTMF Relay at session establishment is determined based on the setting of their respective data element as described below. Table 1 provides a summary of the E-DVA data elements related to CODEC configuration.
+
+**Table 1 – E-DVA CODEC Provisioning**
+
+| Data                   | Type         | Persistence  | Scope     | Stored by      | Written by     | Read by           | Range | Increments | Default |
+|------------------------|--------------|--------------|-----------|----------------|----------------|-------------------|-------|------------|---------|
+| G.711 Packet           | Integer (ms) | Non-volatile | Per E-DVA | CONFIG. SERVER | CONFIG. SERVER | CONFIG. SERVER UE | 10-30 | 10         | 20      |
+| T.38                   | Boolean      | Non-volatile | Per E-DVA | CONFIG. SERVER | CONFIG. SERVER | CONFIG. SERVER UE | N/A   | N/A        | ON      |
+| V.152                  | Boolean      | Non-volatile | Per E-DVA | CONFIG. SERVER | CONFIG. SERVER | CONFIG. SERVER UE | N/A   | N/A        | ON      |
+| DTMF Relay             | Boolean      | Non-volatile | Per E-DVA | CONFIG. SERVER | CONFIG. SERVER | CONFIG. SERVER UE | N/A   | N/A        | ON      |
+| RTCP XR Publish_report | IP address   | Non-volatile | Per E-DVA | CONFIG. SERVER | CONFIG. SERVER | CONFIG. SERVER UE | N/A   | N/A        | n/a     |
+| RTCP XR                | Boolean      | Non-volatile | Per E-DVA | CONFIG. SERVER | CONFIG. ERVER  | CONFIG. SERVER UE | N/A   | N/A        | ON      |
+| RTCP_RATE              | Integer (s)  | Non-volatile | Per E-DVA | CONFIG. SERVER | CONFIG. SERVER | CONFIG. SERVER UE | 0-60  | 1          | 5       |
+
+A value of ON for T.38 enables fax relay on the E-DVA. The E-DVA MUST enable T.38 operation as provisioned via the T.38 data element.
+
+A value of ON for V.152 enables modem relay on the E-DVA. The E-DVA MUST enable V.152 operation as provisioned via the V.152 data element.
+
+A value of ON for DTMF Relay enables DTMF Relay on the E-DVA. The E-DVA MUST enable DTMF Relay operation as provisioned via the DTMF Relay data element.
+
+Publish\_report defines the network address that receives the call statistics report from the E-DVA. The E-DVA MUST send Publish reports at the end of each call.
+
+RTCP XR determines if extended reports for the sake of voice metrics are included within RTCP packets. A value of ON enables RTCP extended reports. Voice metrics can include network and audio metrics as defined in [CODEC-MEDIA].
+
+RTCP\_RATE sets the interval at which RTCP packets are sent from the E-DVA. A value of zero for RTCP\_RATE disables RTCP transmission. The E-DVA MUST send RTCP packets at the rate indicated in the RTCP\_RATE data element.
+
+If a voice call is switched to T.38 or V.152, the E-DVA MUST use the same packet period as the prior voice stream for transmitting data.
+
+## 8.5 Loopback Test Capability
+
+The IPCablecom2 network may initiate a test call to the E-DVA to request that the E-DVA then be set into loopback mode in order for the network to send RTP streams to the E-DVA, and receive the same stream back. This allows the network operator to test the voice path and, potentially, a number of voice/packet performance statistics.
+
+### 8.5.1 Test Call Request Encoding
+
+The IPCablecom2 network indicates, via a specific encoding scheme in the SIP INVITE, that the request will initiate a test call and enable RTP loopback.
+
+To indicate an RTP loopback test call, the INVITE received from the network MUST be encoded with:
+
+- A Require header containing the option tag 'answermode' (see [ID SIP ANSWERMODE]).
+- An Answermode header containing the parameters 'auto;require'.
+- SDP attribute 'loopback' indicating the specific loopback behavior required (see [ID MMUSIC LOOPBACK]).
+- SDP attribute 'loopback-source' indicating that the network is the source of the media that will be the subject of the RTP loopback.
+
+### 8.5.2 E-DVA Requirements on Reception of a Loopback Request
+
+On reception of an INVITE request encoded as defined in this clause, the E-DVA MUST:
+
+- Not alert the subscriber.w4
+- Provide a 200 OK final response to the INVITE
+- Encode the answer SDP provided in the 200 OK according to the rules defined in [ID MMUSIC LOOPBACK]
+
+On reception of RTP packets from the network, once a Loopback mode has been established, the action at the E-DVA is dependent on the contents of the 'loopback' attribute received in the offering SDP from the network.
+
+If the 'loopback' attribute was encoded as 'rtp-pkt-loopback', then E-DVA MUST NOT decode the received RTP packet and instead send the received packet back to the network. The destination IP address and port for the looped RTP is that given in the offering SDP in the initial INVITE.
+
+If the 'loopback' attribute was encoded as 'rtp-media-loopback', then the E-DVA MUST decode and then re-encode the received RTP payload before sending the received packet back to the network if the E-DVA supports media loopback mode. The destination IP address and port for the looped RTP is that given in the offering SDP in the initial INVITE. The E-DVA MUST reject the INVITE with the 'rtp-media-loopback' if the E-DVA does not support the media loopback mode.
+
+The Loopback test session ends upon reception of a BYE from the network on the dialog established by the initial INVITE.
+
+The E-DVA MUST reject an INVITE request encoded as defined in this clause if it has insufficient resources to meet the requirements of the loopback mode. For example, the E-DVA may already be involved in a 3-way call.
+
+The E-DVA SHOULD end the loopback mode with a BYE if the user's request for a 3-way call cannot be serviced due to resource limitations.
+
+# 9 E-DVA Monitoring requirements
+
+The E-DVA is a critical element in the IPCablecom2 architecture. It provides the customer's interface to the service provider's network, and is located outside the service provider's headend. As such, it is critical that the operational status of the E-DVA be monitored in order to provide the quickest information to the service provider. In particular, if the E-DVA fails and is not capable of providing the intended service, the service provider will need be aware in advance of this situation (preferably before the customer).
+
+The minimum goal of fault management should be to isolate failures to a field replaceable unit. Preferably, fault management should be able to identify the failed functional subsystem within the unit. This enables the service provider to dispatch service personnel with the appropriate equipment necessary to troubleshoot and resolve the problem in the least amount of time (i.e., minimize Mean Time To Replacement, or MTTR).
+
+This clause provides the E-DVA monitoring requirements in support of proper fault management. Specifically, it provides the monitoring requirements for three main functional subsystems of the E-DVA: the DOCSIS eCM, the IPCablecom2 E-DVA, and the battery-backup module.
+
+## **9.1 eCM Monitoring**
+
+The E-DVA functions as the customer premises network interface to the IPCablecom2 network and thus enables service to the customer. In particular, within the eDOCSIS-compliant E-DVA, the eCM provides the critical connection between the E-DVA and the IPCablecom2 network [eDOCSIS]. An eCM failure will affect the availability of the IPCablecom2 service.
+
+The E-DVA MUST support the eCM failure detection mechanisms defined by DOCSIS Recommendations [DOCSIS RFv2.0], [DOCSIS OSSIv2.0], and [eDOCSIS].
+
+For the report of the eCM failures, the E-DVA MUST support the event and alarm reporting mechanisms as defined in [RST E-UE Prov].
+
+## **9.2 E-DVA Monitoring**
+
+At the minimum, the E-DVA monitoring MUST utilize the eCM failure detection mechanisms defined by DOCSIS Recommendations [DOCSIS RFv2.0], [DOCSIS OSSIv2.0], and [eDOCSIS].
+
+Additional vendor-specific E-DVA monitoring mechanisms MAY be developed. Such mechanisms can include internal online diagnostics utilized to detect vendor-specific events.
+
+For the report of the E-DVA failures, the E-DVA MUST support the event and alarm reporting mechanisms as defined in [RST E-UE Prov].
+
+## **9.3 Battery-Backup Monitoring**
+
+To maintain operation during the utility AC power outage, the E-DVA MAY provide local power with uninterruptible power supply (UPS) battery backup. If the UPS is provided, the E-DVA MUST support the AC Fail, AC Restore, Replace Battery, Battery Good, Battery Missing, Battery Present, Battery Low, and Battery Not Low alarm state telemetry signals for the monitoring of the battery-backup module. For the report of these telemetry signals, the E-DVA MUST support the event and alarm reporting mechanisms as defined in [RST E-UE Prov].
+
+### **9.3.1 Telemetry Signal 1 – AC Fail**
+
+The active alarm state of this E-DVA signal MUST indicate an "AC Fail" condition, which means that the UPS has detected a failure of the utility AC power and is operating off its battery.
+
+The inactive alarm state of this E-DVA signal MUST indicate an "AC Restored" condition, which means that the UPS has detected the presence of utility AC power and is no longer operating off its battery.
+
+### **9.3.2 Telemetry Signal 2 – Replace Battery**
+
+The active alarm state of this E-DVA signal MUST indicate a "Replace Battery" condition, which means that the UPS, via internal test mechanisms outside the scope of this Recommendation, has determined that the battery can no longer maintain a charge sufficient enough to provide adequate battery backup and thus is failing and should be replaced with a new battery.
+
+The inactive alarm state of this E-DVA signal MUST indicate a "Battery Good" condition.
+
+### **9.3.3 Telemetry Signal 3 – Battery Missing**
+
+The active alarm state of this E-DVA signal MUST indicate a "Battery Missing" condition, which means that the UPS has detected that a battery is not present and a battery should be installed in the UPS.
+
+The inactive alarm state of this E-DVA signal MUST indicate a "Battery Present" condition.
+
+### **9.3.4 Telemetry Signal 4 – Battery Low**
+
+The active alarm state of this E-DVA signal MUST indicate a "Battery Low" condition, which means that the battery has sufficiently discharged to the point where a power source can only be maintained for a short while longer.
+
+The inactive alarm state of this E-DVA signal MUST indicate a "Battery Not Low" condition, which means that the battery has charged above the "battery low" threshold.
+
+# Appendix I
+
+## Example of a power calculation
+
+(This appendix does not form an integral part of this Recommendation)
+
+A projected "typical" E-DVA traffic model has been developed based on [GR 517] and [Key Smith] and inputs from cable operators. With this qualification, this model may be used to make an initial calculation of long-term average power.
+
+**Table I.1 – E-DVA Traffic Model**
+
+| Line Number                                                              | E-DVA Line 1   | E-DVA Line 2    | E-DVA Line 3   | E-DVA Line 4   | Cable Modem Data |
+|--------------------------------------------------------------------------|----------------|-----------------|----------------|----------------|------------------|
+| Assumed Use                                                              | Voice          | Modem/Voice     | Voice/Fax      | Voice          | High Speed Data  |
+| Usage (Erlangs)                                                          | .11            | .11             | .05            | .05            | .11              |
+| Line Penetration (Normalized by Penetration)                             | 100%           | 80%             | 50%            | 25%            | 25%              |
+| Average Ringing Period                                                   | 14 s           | 14 s            | 14 s           | 14 s           | n/a              |
+| Average call length<br>E-DVA w/o Data Service<br>E-DVA with Data Service | 5 min<br>5 min | 26 min<br>5 min | 5 min<br>5 min | 5 min<br>5 min | n/a<br>n/a       |
+| Average Data Rate to Subscriber                                          | n/a            | n/a             | n/a            | n/a            | 100 kbit/s       |
+| Average Data Rate From Subscriber                                        | n/a            | n/a             | n/a            | n/a            | 10 kbit/s        |
+
+The average cable modem data rates shown in Table I.1 assume that when a user is active on the system (i.e., .11 erlang), the user is interpreting or typing information during 90% of the active session, and no significant data is flowing through the data interface. Data interface rates of 1 Mbit/s to the subscriber and 100 kbit/s from the subscriber are assumed during the remaining 10% of the session. The averages are assumed to be long term and are considered over the entire domain of a power node (i.e., 100's of E-DVAs).
+
+## Example of an analog port requirement
+
+This Appendix uses the following additional informative references:
+
+- [ANSI T1.401] ANSI T1.401, *Network to Customer Installation Interfaces – Analog Voice grade Switched Access Lines Using Loop-Start or Ground Start Signaling with Line-Side answer supervision feature*, 2000.
+- [GR 30] Telcordia GR-30-CORE, *LSSGR: Voiceband Data Transmission Interface*, December 1998, FR-64.
+- [GR 57] Telcordia, GR-57-CORE, Issue 1, October 2001, *Functional Criteria for Digital Loop Carrier (DLC) Systems*.
+- [GR 303] Telcordia GR-303, Issue 4, *Integrated Digital Loop Carrier System Generic Requirements, Objectives, and Interface*, December 2002,
+- [GR 499] Telcordia GR-499-CORE, Issue 4, *Transport Systems Generic Requirements (TSGR): Common Requirements*, September 2004.
+- [GR 506] Telcordia GR-506-CORE, *LSSGR: Signaling for Analog Interfaces*, November, 1996, FR-64.
+
+- [GR 517] Telcordia (Bellcore) GR-517-CORE, Issue 1, *LEC Traffic Environment Characteristics*, December 1998.
+- [GR 909] Telcordia GR-909-CORE, Issue 2, *Generic Requirements and Objectives for Fiber in the Loop (FITL) Systems*, December 2004.
+- [GR 1089] Telcordia GR-1089-CORE, Issue 4, *Generic Requirements for Electronic Equipment Cabinets, Electromagnetic Compatibility and Electrical Safety Generic Criteria for Network Telecommunications Equipment*, June 2006.
+- [GR 1401] Telcordia GR 1401, *LSSGR: Visual Message Waiting Indicator Generic Requirements* (FSD 01-02-2000), June 2000, FR-64.
+- [SR-TSV-002476] Telcordia Special Report, SR-TSV-002476, *CPE Compatibility Considerations for the Voiceband Data Transmission Interface*, December 1992.
+- [EN 300 659-1] ETSI EN 300 659-1, *Access and Terminals (AT); Analogue access to the Public Switched Telephone Network (PSTN); Subscriber line protocol over the local loop for display (and related) services; Part 1: On-hook data transmission*, January 2001.
+- [EN 300 659-3] ETSI EN 300 659-3, *Access and Terminals (AT); Analogue access to the Public Switched Telephone Network (PSTN); Subscriber line protocol over the local loop for display (and related) services; Part 3: Data link message and parameter codings*, January 2001.
+- [ANSI T1.508] ANSI T1.508, *Network Performance – Loss Plan for Evolving Digital Networks*, 1998.
+- [TIA-912a] TIA-912a, *Telecommunication – IP Telephony Equipment – Voice Gateway Transmission Requirements*, August 2004.
+- [TSB-122a] TIA/EIA/TSB 122a, *Telecommunications – IP Telephony Equipment – Voice Router/Gateway loss and Level Plan Guidelines*, March 2001.
+
+This interface is similar to the FITL (fibre in the loop) interface described by Telcordia in [GR 909]. Thus GR-909-CORE has been used as the model for generating these requirements. For basic IPCablecom2 services, the requirements can be divided into four categories:
+
+- Loop Start Signaling
+- General Supervision
+- General Ringing
+- Voice Grade Analog Transmission
+
+The E-DVA analog 2-wire interface requirements are listed in the following clauses.
+
+For the purpose of this clause, the subscriber twisted pair copper wiring (typically the wiring inside the subscriber's premises) that is connected to the E-DVA analog port will be referred to as the "loop". Note that this usage is different from the way these terms may be used in the context of the PSTN, in which the "loop" is defined as the transmission path between a telephone company central office and a customer's premises. The "loop" referred to in this clause, in PSTN terms, would typically be referred to as "premises wire" or "inside wire". References here to "loops" and "transmission paths" should not be confused with links from customer premises to either a telephone company office or to a cable operator's headend.
+
+## **I.1 Loop Start Signaling**
+
+### **I.1.1 DC Supervisory Range**
+
+The DC supervisory range MUST meet:  $RDC \geq 450$  ohms. RDC is the DC supervisory range. The actual value of RDC depends on the resistance of the loop wire from the E-DVA (the subscriber's inside wiring). That is,  $RDC = 430$  ohms +  $Rloop$ . Note that this accommodates a drop of 150 metres of service wire at 65 degrees Celsius.
+
+Reference: section 4.1.1 of [GR 909].
+
+### **I.1.2 Idle State Voltage**
+
+The idle state is when the loop is open or on-hook. In this state, the idle voltage MUST:
+
+- be  $42.75 Vdc \leq VIDLE \leq 80 V DC$ ; and
+- comply with National electrical safety requirements.
+
+In this state, the idle voltage SHOULD:
+
+- have a Ring that is negative with respect to tip
+- have Ring-to-ground and tip-to-ground voltages that are  $< 0$
+
+Reference: section 4.1.2 of [GR 909].
+
+### **I.1.3 Loop Closure Detection**
+
+Loop closure is off-hook. Detection of loop closure in the E-DVA MUST meet:
+
+- Resistance  $\leq RDC$  between tip and ring is loop closure
+- Resistance  $\geq 10$  k ohms between tip and ring is not loop closure
+
+Reference: section 4.1.4 of [GR 909].
+
+### **I.1.4 Loop Open Detection**
+
+Loop open is on-hook. Detection of loop open in the E-DVA MUST meet:
+
+- Resistance  $\geq 10$  k ohms is loop open
+- Resistance  $\leq RDC + 380$  ohms is not loop open
+
+The E-DVA MUST be able to distinguish between a hit, dial pulse, flash, or disconnect.
+
+Reference: section 4.1.5 of [GR 909].
+
+### **I.1.5 Off-Hook Delay**
+
+The E-DVA MUST meet the timing requirements R11-33 of [GR 506] for detecting a subscriber origination request (off-hook).
+
+The E-DVA MUST be able to generate the local dial tone within 50 ms of detecting a subscriber origination request (off-hook).
+
+The E-DVA MUST be capable of establishing a 2-way voice signal transmission capability on the loop established within 50 ms of detecting the subscriber termination request (off-hook).
+
+Reference: section 4.1.7 of [GR 909].
+
+### **I.1.6 Flash Hook Delay**
+
+The E-DVA MUST meet the timing requirements in section 12 of [GR 506] for detecting a flash signal and a subscriber termination request (on-hook).
+
+The E-DVA MUST be able to signal to the network about a flash signal within 50 ms of detecting such an event.
+
+### **I.1.7 On-Hook Delay**
+
+The E-DVA MUST meet the timing requirements in section 12 of [GR 506] for detecting an on-hook signal and a subscriber termination request (on-hook).
+
+The E-DVA MUST be able to signal to the network about an on-hook signal or a subscriber termination request within 50 ms of detecting such an event.
+
+### **I.1.8 Ringsplash**
+
+When a feature requires one 500 ms ringsplash, the E-DVA MUST apply one  $500 \pm 50$  ms ring burst to the line.
+
+Reference: section 4.1.9 of [GR 909].
+
+### **I.1.9 Distinctive Alerting**
+
+Defined ring cadences MUST be applied to the drop within  $\pm 50$  ms resolution. The E-DVA MUST be able to apply any of the distinctive alerting patterns described in the IPCablecom2 Residential SIP Telephony Feature Recommendation [RSTF] on the line when signaled by the IPCablecom2 network.
+
+Reference: section 4.1.10 of [GR 909].
+
+### **I.1.10 Transmission Path**
+
+The E-DVA MUST support part-time on-hook transmission capabilities: part-time = within 400 ms after a ringsplash. On-hook transmission provides the capability of transmitting a voiceband signal in both directions on the loop when the loop is open (on-hook).
+
+Reference: section 4.1.15 of [GR 909].
+
+## **I.2 General Supervision**
+
+### **I.2.1 Off-Hook Loop Current**
+
+The E-DVA MUST provide at least 20 mA of loop current in the off-hook state. Loop voltage is such that the ring conductor is negative with respect to the tip conductor.
+
+Reference: section 4.2.1 of [GR 909].
+
+### **I.2.2 Immunity to Line Crosses**
+
+Shorts between tip-to-tip, tip-to-ring, or ring-to-ring involving two or more lines MUST NOT damage the E-DVA. Shorts between tip-to-ground or ring-to-ground involving one or more lines MUST NOT damage the E-DVA.
+
+Reference: section 4.4.3 of [GR 909].
+
+### **I.2.3 System Generated Open Intervals**
+
+When in the loop closure state (off-hook), interruptions to loop current feed on the E-DVA MUST NOT exceed 100 ms.
+
+Reference: section 4.4.5 of [GR 909].
+
+Network Disconnect (or Loop Current Feed Open) is signaled by the network side of a loop start interface when the distant end releases while the CPE is offhook. Typically, this signal is used to notify electronic equipment, such as answering machines, that the caller has hung up. When provisioned to do so via the NetDisc date element, the E-DVA MUST remove DC bias for 1 second  $\pm 400$  milliseconds when a call has been cleared by the network.
+
+**Table I.2 – E-DVA Network Disconnect Signaling Event**
+
+| Data    | Type         | Persistence  | Scope    | Stored by | Written by     | Read by               | Range     | Increments | Default |
+|---------|--------------|--------------|----------|-----------|----------------|-----------------------|-----------|------------|---------|
+| NetDisc | Integer (ms) | Non-volatile | Per Line | E-DVA     | CONFIG. SERVER | CONFIG. SERVER, E-DVA | 0 to 2000 | 100        | 1000    |
+
+NetDisc value of 0 indicates that the E-DVA MUST NOT remove DC bias when a call disconnects. The default value of NetDisc should be 1000 milliseconds. The default NetDisc for Answer Signal should be "off".
+
+### I.2.4 Open Switching Interval Distortion
+
+The following are the Open Switching Interval Distortion requirements. When in the loop closure state and providing loop current feed, E-DVA loop current feed open commands of duration, T MUST have resolution  $\pm 25$  ms for  $50 \leq T \leq 1000$  ms. When in the above state, the E-DVA MUST continue to maintain loop closure with no interruptions  $> 1$  ms.
+
+- Loop current feed open MUST NOT exceed 5 s in duration.
+- Loop current feed is an interruption of the loop current sourced on the drop.
+
+[GR 909] specifies that these closure requirements MUST be satisfied for both on-hook and off-hook.
+
+Reference: section 4.4.6 of [GR 909].
+
+### I.2.5 Answer Supervision Signal (AnsSup)
+
+Answer Supervision (also called battery reversal, reverse DC bias, or Reverse Loop Current Feed) is signaled when the distant end answers a call originated by the CPE. Typically, this signal is used to notify electronic equipment such as PBXs which have a local billing system that a call has been answered. When provisioned to do so via the AnsSup data element, the E-DVA MAY reverse DC bias when a call has been answered.
+
+**Table I.3 – E-DVA Answer Supervision Event**
+
+| Data   | Type    | Persistence  | Scope    | Stored by | Written by     | Read by               | Range  | Increments | Default |
+|--------|---------|--------------|----------|-----------|----------------|-----------------------|--------|------------|---------|
+| AnsSup | Boolean | Non-volatile | Per Line | E-DVA     | CONFIG. SERVER | CONFIG. SERVER, E-DVA | Off/On | N/A        | Off     |
+
+The default AnsSup value for Answer Signal should be "off".
+
+### I.2.6 Dial Pulsing
+
+Dial pulses MUST be collected at the E-DVA. The digits are gathered according to the digit map and all digits are sent in a single message. The E-DVA MUST support 8-12 pps with a 58-64% break.
+
+Reference: section 4.4.9 of [GR 909].
+
+### I.2.7 DTMF Signaling
+
+The E-DVA MUST support the use of DTMF for both dialed digits and for the relay of digits as part of an established session. When dialing the DTMF, signaling MUST be collected at the E-DVA. The digits are gathered according to the digit map and all digits are sent in a single message.
+
+The E-DVA MUST NOT amplitude overload at the maximum expected DTMF signal level per [ANSI T1.401]. ([ANSI T1.401] describes the maximum DTMF signal level.) Amplitude overload is any output frequency between 0-12 kHz at a power level greater than -28 dBm0, when the input frequency is between 600-1500 Hz at a power level equal to the maximum expected DTMF signal level.
+
+The E-DVA MUST apply DTMF tones to the audio path, or the E-DVA MUST generate DTMF relay per [CODEC-MEDIA] as dictated from the negotiated SDP associated with the session.
+
+The E-DVA MUST offer DTMF relay within SDP upon session origination as provisioned in the DTMF RELAY feature data element.
+
+**Table I.4 – DTMF Relay Offer**
+
+| Data       | Type    | Persistence  | Scope     | Stored by      | Written by     | Read by              | Range  | Increments | Default |
+|------------|---------|--------------|-----------|----------------|----------------|----------------------|--------|------------|---------|
+| DTMF RELAY | Boolean | Non-volatile | Per E-DVA | CONFIG. SERVER | CONFIG. SERVER | CONFIG. SERVER E-DVA | Off/On | N/A        | ON      |
+
+The default value of DTMF\_RELAY = ON instructs the E-DVA to offer DTMF relay within SDP upon session origination.
+
+### I.2.8 Dialtone Removal
+
+The E-DVA MUST remove dialtone within 250 ms of detecting the first dialed digit.
+
+Subsequent digit analysis in accordance with the digit map may result in re-application of dialtone by the E-DVA. The requirement for dialtone removal also applies to such a re-application of the dialtone.
+
+Note, however, that the act of re-applying the dialtone is a digit map action and independent of this requirement.
+
+## I.3 General Ringing
+
+### I.3.1 Alerting Signals
+
+The E-DVA MUST support unbalanced or balanced ringing. The applied cadence MUST be within ±50 ms of the defined cadence. Nominal cadence has a 6-s period with 1.7 to 2.1 s ringing and 3.1 to 5.5 s of silence.
+
+For Unbalanced Ringing, the alerting cadence is applied to ring with tip grounded. The DC component during ringing is such that the ring conductor is negative with respect to tip.
+
+For Balanced Ringing, the alerting cadence is applied to both tip and ring, typically 180° out of phase, with or without a DC component.
+
+Reference: section 4.5.2 of [GR 909]. Modified for IPCablecom2 for optional balanced ringing.
+
+### I.3.2 Ringing Delay
+
+Ringing MUST be applied within 200 ms of the E-DVA receiving SIP INVITE with SDP. The cadence MUST be used as per PACM configuration entered at any point (i.e., the cadence may start with the silent period).
+
+Reference: section 4.5.3 of [GR 909].
+
+### I.3.3 Ringing Source
+
+The E-DVA Ringing Source MUST meet the duration-limited source safety requirements of [GR 1089].
+
+- The E-DVA ringing frequency MUST be  $20 \pm 1$  Hz.
+- The E-DVA ringing source DC component (offset) MUST be  $\leq 75$  Vdc.
+- The E-DVA Ringing Source MUST meet  $1.2 \leq \text{peak-to-rms voltage ratio} \leq 1.6$ .
+- The E-DVA ringing source bridged C-weighted noise MUST be  $\leq 90$  dBrnC, when referenced to 900 ohms during ringing (i.e., the 20 Hz component  $< 0$  dBm), and the analog voiceband lead conducted emissions criteria of [GR 1089].
+
+Reference: section 4.5.4 of [GR 909].
+
+### **I.3.4 Ringing Capability**
+
+The minimum ringing voltage of the E-DVA MUST meet 40 Vrms across a 5 REN load on a drop with resistance  $\leq R_{DC} - 400$  ohms.
+
+Reference: section 4.5.5 of [GR 909].
+
+### **I.3.5 Ringing Capacity**
+
+The E-DVA MUST be capable of supporting 5 REN per analog line as described in [GR 909].
+
+Reference: section 4.5 of [GR 909].
+
+### **I.3.6 Ring Trip**
+
+The E-DVA Ringing MUST be removed within 200 ms of detecting loop closure.
+
+Reference: section 4.5.7 of [GR 909].
+
+### **I.3.7 Ring Trip Detect Delay**
+
+The E-DVA MUST be able to detect a ring trip within 300 ms.
+
+Reference: section 4.5.8 of [GR 909].
+
+### **I.3.8 Ring Trip Immunity**
+
+E-DVA Ringing MUST NOT be tripped when a termination of 10 k ohms in parallel with 6 uF is applied between tip and ring.
+
+E-DVA Ringing MUST NOT be tripped when a termination of 200 ohms is applied between tip and ring for  $\leq 12$  ms.
+
+Reference: section 4.5.9 of [GR 909].
+
+## **I.4 Voice Grade Analog Transmission**
+
+The IPCablecom2 system utilizes digital transmission of voice signals to and from the DVA. The DVA converts between the digital voice signal on the IP network and the analog voice signal on the tip and ring loop. System impairments in the digital network, such as packet loss, can affect the voice signal but are outside the control of the DVA. Therefore, this clause defines the analog voiceband requirements of the DVA and assumes an error-free digital network.
+
+These requirements are derived from the PSTN, which, in some cases, utilizes analog transmission from a headend central office switch to a customer. Typically, the reference point by which these requirements are measured is the middle of the switch (digital to analog). This reference point is referred to as the 0 Transmission Level Point (TLP) and could be thought of as any point in the digital portion of the network.
+
+Note that these are not end-to-end analog requirements since they apply to a single digital to analog conversion point (a typical voice call will be analog at each end with a digital network connecting the two ends). The 0 TLP of the IPCablecom2 system is any point in the digital IP network. The digital IP network, for voice signal transmission purposes, extends all the way to the DVA where
+
+the digital to analog conversion occurs. These requirements only apply to the G.711 audio codec as specified in [CODEC-MEDIA]. Transmission requirements for the other compression algorithms specified in [CODEC-MEDIA] are not yet defined.
+
+In general, all these requirements MUST be satisfied for both on-hook and off-hook parameters.
+
+### **I.4.1 Input Impedance**
+
+The E-DVA input impedance MUST meet:
+
+- 600 ohms nominal
+- ERL (echo return loss) > 26 dB (29 dB objective)
+- SRL (singing return loss) > 21 dB (24 dB objective)
+
+Reference: section 5.3.3 of [GR 909].
+
+### **I.4.2 Hybrid Balance**
+
+The E-DVA Hybrid Balance MUST meet, where LT1 is transmit loss and LR1 is receive loss at 1004 Hz:
+
+- ERL > 21 dB (26 dB objective)
+- SRL > 16 dB (21 dB objective)
+- ERL = 15 + LT1 + LR1
+- SRL = 10 + LT1 + LR1
+
+Reference: section 5.3.4 of [GR 909].
+
+### **I.4.3 Longitudinal Balance**
+
+The E-DVA Longitudinal Balance MUST meet:
+
+- 200 Hz: min > 45 dB, ave > 50 dB (ave > 61 dB objective)
+- 500 Hz: min > 45 dB, ave > 50 dB (ave > 58 dB objective)
+- 1000 Hz: min > 45 dB, ave > 50 dB (ave > 52 dB objective)
+- 3000 Hz: min > 40 dB, ave > 45 dB
+
+Reference: section 5.3.5 of [GR 909].
+
+### **I.4.4 E-DVA Loss**
+
+The E-DVA loss plan is part of a network loss plan, which considers not only the analog loss between end points, but also the end-to-end delay, the loopback delay, noise and echo cancellation. Guidance in setting the DVA loss can be found in [ANSI T1.508], [TSB-122a], and Table 1 of [TIA-912a], which defines various termination points across a network.
+
+Additional consideration must be taken due to the short analog loop architecture with the DVA. In this configuration, there is a potential risk of G.711 codec overload with DTMF signaling. In this configuration, it is recommended that an additional loss in each direction (D/A and A/D) be configured in the DVA.
+
+Additionally, variations in network deployments result in variations in the end-to-end and loopback delays. These delay variations must also be considered in setting the loss plan values.
+
+Due to these considerations, for each telephony line, the DVA MUST support two provisioned loss parameters, one for the D/A direction (towards the subscriber) and one for A/D direction (from the subscriber).
+
+The E-DVA MUST support a provisioning range of 0 dB to 12 dB of loss in 1 dB increments.
+
+**Table I.5 – E-DVA Provisioned Loss Plan**
+
+| <b>Data</b> | <b>Type</b>  | <b>Persistence</b> | <b>Scope</b> | <b>Stored by</b> | <b>Written by</b> | <b>Read by</b>        | <b>Range</b> | <b>Increments</b> | <b>Default</b> |
+|-------------|--------------|--------------------|--------------|------------------|-------------------|-----------------------|--------------|-------------------|----------------|
+| D/A Loss    | Integer (dB) | Non-volatile       | Per Line     | E-DVA            | CONFIG. SERVER    | CONFIG. SERVER, E-DVA | 0 to 12      | 1                 | 6              |
+| A/D Loss    | Integer (dB) | Non-volatile       | Per Line     | E-DVA            | CONFIG. SERVER    | CONFIG. SERVER, E-DVA | 0 to 12      | 1                 | 6              |
+
+NOTE – In loss planning, positive numbers represent loss and negative numbers represent gain.
+
+### **1.4.5 E-DVA Loss Tolerance**
+
+E-DVA Loss Tolerance MUST be within  $\pm 0.5$  dB of the provisioned loss.
+
+Reference: clause 6.5.4.1 of [TIA-912a].
+
+### **1.4.6 Frequency Response**
+
+The E-DVA Off-hook transmission loss between 400-2800 Hz MUST be within  $-0.5$  to  $+1$  dB of the loss at 1004 Hz using a 0 dBm0 signal.
+
+The E-DVA On-hook transmission loss between 400-2800 Hz MUST be within  $-1$  to  $+2$  dB of the loss at 1004 Hz using a 0 dBm0 signal (+ means more loss, – means less loss).
+
+Reference: section 6.1.9 of [GR 57].
+
+### **1.4.7 60 Hz Loss**
+
+The E-DVA transmission path loss at 60 Hz MUST be at least 20 dB greater than the off-hook transmission path loss at 1004 Hz. The intention is to limit the encoding of 60 Hz induction in the A/D direction.
+
+Reference: section 6.1.10 of [GR 57].
+
+### **1.4.8 Amplitude Tracking**
+
+The E-DVA deviation of a 1004 Hz off-hook transmission path loss relative to the loss of a 0 dBm0 input signal MUST meet:
+
+- $-37$  to  $+3$ -dBm0 input:  $\pm 0.5$  dB max ( $\pm 0.25$  dB ave)
+- $-50$  to  $-37$ -dBm0 input:  $\pm 1.0$  dB max ( $\pm 0.5$  dB ave)
+- $-55$  to  $-50$ -dBm0 input:  $\pm 3.0$  dB max ( $\pm 1.5$  dB ave)
+
+The E-DVA deviation of a 1004 Hz on-hook transmission path loss relative to the loss of a 0 dBm0 input signal MUST meet:
+
+- $-37$  to 0 dBm0:  $\pm 0.5$  dB max
+
+Reference: section 6.1.11 of [GR 57].
+
+### **1.4.9 Overload Compression**
+
+The increase in the E-DVA off-hook transmission path loss at 1004 Hz relative to the loss of a 0 dBm0 input signal MUST meet the following:
+
+- $+3$  dBm0 input:  $\leq 0.5$  dB increased loss
+- $+6$  dBm0 input:  $\leq 1.8$  dB increased loss
+- $+9$  dBm0 input:  $\leq 4.5$  dB increased loss
+
+This is to ensure the receiver off-hook signal can be transmitted.
+
+Reference: section 6.1.12 of [GR 57].
+
+### **1.4.10 Idle Channel Noise**
+
+The idle channel noise MUST NOT exceed 20 dBrnC at the output of the E-DVA (18 dBrnC objective).
+
+Reference: section 6.1.13 of [GR 57].
+
+### **1.4.11 Signal to Distortion**
+
+The E-DVA ratio of the output signal to output C-notched noise with a 1004 Hz input signal while providing an onhook and off-hook transmission path MUST meet:
+
+- 0 to -30-dBm0 input: >33-dB ratio
+- -30 to -40-dBm0 input: >27-dB ratio
+- -40 to -45-dBm0 input: >22-dB ratio
+
+Reference: section 5.3.15 of [GR 909] and section 6.1.14 of [GR 57].
+
+### **1.4.12 Impulse Noise**
+
+The E-DVA impulse noise MUST meet:
+
+- $\leq 15$  impulses in 15 minutes with no holding tone applied at a threshold of 47 dBrnC0.
+- $\leq 15$  impulses in 15 minutes with a -13 dBm0 tone at 1004 Hz at a threshold of 65 dBrnC0.
+
+These SHOULD be met for both the on-hook and off-hook transmission paths. For a line under test, other lines on the E-DVA SHOULD be active (off-hook, dialing, ringing, etc.).
+
+Reference: section 5.3.16 of [GR 909] and section 6.1.15 of [GR 57].
+
+### **1.4.13 Intermodulation Distortion**
+
+The E-DVA intermodulation distortion MUST meet:
+
+- $R2 > 43$  dB using a -13 dBm0 input signal
+- $R3 > 44$  dB using a -13 dBm0 input signal
+
+R2 and R3 are the 2nd and 3rd order intermodulation products measured using the IEEE 743-1984 4-tone method.
+
+Reference: section 6.1.16 of [GR 57].
+
+### **1.4.14 Single Frequency Distortion**
+
+The E-DVA single frequency distortion MUST meet:
+
+- Using a 0 dBm0 input signal between 0-12 kHz, the output between 0-12 kHz  $< -28$  dBm0
+- Using a 0 dBm0 input signal between 1004-1020 Hz, the output between 0-4 kHz  $< -40$  dBm0
+
+Reference: section 6.1.17 of [GR 57].
+
+### **1.4.15 Generated Tones**
+
+The E-DVA generated tones MUST meet:
+
+- $< -50$  dBm0 between 0-16 kHz.
+
+Reference: section 5.3.20 of [GR 909].
+
+### 1.4.16 Peak-to-Average Ratio
+
+The E-DVA peak-to-average ratio of transmission paths MUST meet:
+
+- P/AR > 90 with a -13 dBm0 input level. On-hook and off-hook transmission paths.
+
+Reference: section 6.1.19 of [GR 57].
+
+### 1.4.17 Channel Crosstalk
+
+With a 0-dBm0 signal between 200-3400 Hz applied to a line, other lines on the E-DVA MUST meet <-65 dBm0 C-message weighted output between 200-3400 Hz.
+
+Reference: section 5.3.22 of [GR 909] and section 6.1.20 of [GR 57].
+
+## 1.5 Out of Service Requirements
+
+Clause 7.1.7 of [RSTF], In-Service and out-of-service states, defines the conditions where the E-DVA determines a network availability state and uses one of several analog line supervisory tones (dial tone, re-order tone, etc.) to indicate to the end user or device the current network state when a connection is attempted (E-DVA off hook state).
+
+In addition to supervisory tones, some end user devices (security systems) also determine network connection likelihood by detecting the analog telephony DC bias at the E-DVA telephony termination point. This technique continuously monitors the DC bias and the loss of DC bias is interpreted by the security system as an alarm state. This type of alarm service, therefore, also requires mechanisms to manage the analog telephony DC bias signal both in the E-DVA on-hook and off-hook state to indicate the current network availability state.
+
+The goal must be to provide E-DVA telephony termination point conditions (DC bias and supervisory tone signals) consistent with historical PSTN services while also providing a method where planned or scheduled network or E-DVA operations (network maintenance, software downloads, reboots) do not cause unwanted or inappropriate security alarms.
+
+Due to the fact that end user alarms are subject to the E-DVA and network availability states, including short term, planned outages, it is required to allow the service provider to provision various parameters related to network availability state including planned outages, signaling types, timer durations etc. to properly signal the current system state to the end user and the end user devices.
+
+### 1.5.1 E-DVA On-Hook State
+
+In this E-DVA state, the DC bias is the signaling method to indicate the Network/E-DVA in/out-of-service state. The E-DVA MUST support provisioning of the On-Hook state DCbias. The Operator is able to provision planned, scheduled service times not to be signaled as an out-of-service state pending a maximum duration element.
+
+DCbiasSig element enables/disables the DCbias management per provisioned values on a per telephony port basis.
+
+The E-DVA MUST perform DCbias per DCbias provisioned elements with a DCbiasSign element value of 0.
+
+A value of 1 indicates that the DCbias is not controlled by the provisioned elements.
+
+DCbiasMax element sets the maximum period of time that a DCbias is to be maintained following an E-DVA reboot requiring an in-service State re-establishment per [RSTF]. The E-DVA MUST maintain DCbias following an E-DVA reboot requiring an in-service State re-establishment per [RSTF] for the time period indicated in the DCbiasMax element.
+
+Upon any reset or reboot, the E-DVA SHOULD NOT remove DCbias from the telephony termination point for more than the Network Disconnect Interval (typically 1 second  $\pm$
+
+400 milliseconds). The E-DVA MUST NOT remove DCbias for more than 5 seconds, as long as the operational AC or battery power supply to the E-DVA is maintained across such an initialization event. An E-DVA then MUST comply with the DCbiasMax element. Note that not every security system will accept a 5-second DCbias removal time without alarming. Therefore, it is important to minimize any outage time under any condition.
+
+If the Network/E-DVA fails to re-establish the in-service state per [RSTF] during the DCbiasMax duration, the E-DVA MUST remove the DCbias from the telephony port when the DCbiasMax duration expires.
+
+If the Network/E-DVA succeeds to re-establish the in-service state per [RSTF] during the DCbiasMax duration, the E-DVA MUST cancel the DCbiasMax resulting in the DCbias being maintained on the telephony port in support of normal telephony signaling requirements.
+
+DCbiasHold element sets the period of time that a DCbias is maintained following an out-of-service state per [RSTF]. The E-DVA MUST maintain DCbias following an out-of-service state per [RSTF] for the period of time indicated in the DCbiasHold element.
+
+If the DCbiasHold duration expires, the E-DVA MUST remove DCbias from the telephony port.
+
+If the Network/E-DVA succeeds to re-establish the in-service state per [RSTF] during the DCbiasHold duration, the E-DVA MUST cancel DCbiasHold resulting in the DCbias being maintained on the telephony port in support of normal telephony signaling requirements.
+
+DCbiasEnable element sets a delay time period prior to reapplying DCbias on the E-DVA telephony port following the re-establishment of the in-service state per [RSTF] and following a DCbias removal. This avoids "race" conditions between the Network/E-DVA transitions from inappropriately signaling to the end user security system. The E-DVA MUST reapply DCbias on the telephony port following the re-establishment of the in-service state per [RSTF] and following a DCbias removal after the delay time period indicated by the DCbiasEnable element.
+
+**Table I.6 – Network/E-DVA On Hook In/Out of Service**
+
+| Data         | Type              | Persistence  | Scope    | Stored by | Written by     | Read by                 | Range     | Default |
+|--------------|-------------------|--------------|----------|-----------|----------------|-------------------------|-----------|---------|
+| DCbiasSig    | Boolean           | Non-volatile | Per Line | E-DVA     | CONFIG. SERVER | CONFIG. SERVER<br>E-DVA | n/a       | false   |
+| DCbiasMax    | Integer (seconds) | Non-volatile | Per Line | E-DVA     | CONFIG. SERVER | CONFIG. SERVER<br>E-DVA | 0 to 2400 | 1200    |
+| DCbiasHold   | Integer (seconds) | Non-volatile | Per Line | E-DVA     | CONFIG. SERVER | CONFIG. SERVER<br>E-DVA | 0 to 1200 | 600     |
+| DCbiasEnable | Integer (seconds) | Non-volatile | Per Line | E-DVA     | CONFIG. SERVER | CONFIG. SERVER<br>E-DVA | 0 to 60   | 5       |
+
+#### **Considerations:**
+
+- 1) During call processing states, the E-DVA MUST NOT remove DCbias from the telephony termination point for longer than the Network Disconnect Interval (typically 1 second  $\pm$  400 milliseconds).
+- 2) The echo canceller in the E-DVA MUST be able to pass test 14 in [G.168] when a V-series low-speed (< 9.6 kbit/s) modem is used which does not send a 2100 Hz disable tone with phase reversals. This is not unique to E-DVA to home security systems but is reflective of compliance to ITU-T V.25 requirements for in band analog modem signaling.
+
+### **I.5.2 E-DVA Off Hook State**
+
+In this E-DVA state, In-Service and out-of-service states MUST be supported as per [RSTF].
+
+Some E-DVA telephony termination ports may be used by security systems which may require the removal of DCbias to signal an alarm state. The enabling of the DCbiasSig element which enables/disables the DCbias management per provisioned values on a per telephony port basis will provide selective management of the DCbias signaling on a per telephony port basis.
+
+All sub-elements of DCbiasSig MUST be supported if DCbiasSig is enabled.
+
+### **I.5.3 DTMF Signaling**
+
+Some Home Alarm systems use proprietary DTMF signaling protocols. These protocols assume DTMF decoders and encoders meet Telcordia or ETSI standards. This places specific requirements on the E-DVA with respect to DTMF relay. DTMF telephone-events MUST be fully played out by an egress gateway according to the duration specified in the event subject to an optional minimum play-out duration. The DTMF events MUST be provisioned on the E-DVA endpoint per the [CODEC-MEDIA] to reflect Telcordia [GR 506] section 15.4.8, DTMF Signal Duration R15-52. DTMF signals generated by an E-DVA MUST have a signal duration of 50 milliseconds.
+
+### **I.5.4 Expanded Network Service Outages**
+
+While services have been offered to provide operators with methods to minimize Home Security System alarms during scheduled or known periods of network un-availability, situations may still exist where it is desirable for the operator to further expand the DCbias durations beyond the provisioned values. Under these cases, the Operator may remotely direct the E-DVA to expand the current DCbias duration times for a single event so as to provide short-term maintenance flexibility while still maintaining Home Security System requirements.
+
+## **1.6 Message Waiting Indicator**
+
+The E-DVA MUST follow the general requirements on the Message Waiting Indicator (MWI) given in [RSTF].
+
+Upon receiving the NOTIFY message from the MWI Application Server, the E-DVA MUST present the corresponding MWI to the user's CPE device via a MWI tone, a MWI voice announcement, a MWI FSK signal, or a MWI DTMF signal, according to the provisioned UE MWI Tone Indication, UE MWI Voice Announcement Indication, UE MWI FSK Indication and UE MWI DTMF Indication data parameters in Table I.7. The following are additional requirements on MWI:
+
+- The MWI FSK or DTMF signal is presented to the user's CPE device through the analog port on the E-DVA when the CPE device is on-hook. In presenting these signals, the E-DVA MUST follow the corresponding requirements in [GR 30] section 2.3.2, [SR-TSV-002476], [GR 1401], [GR 506], [EN 300 659-1] clause 6.2, and [EN 300 659-3] clause 5.2.2.
+- The MWI tone or voice announcement MUST be presented to the user's CPE device through the analog port on the E-DVA when the CPE device goes off-hook.
+- If the MWI arrives while the line is busy, the E-DVA MUST delay the presentation until the line goes back to the idle state.
+
+The E-DVA can have built-in capabilities to present the MWI signals in a visual or audible format directly to the user. Such local capabilities are vendor-specific and are outside the scope of this Recommendation.
+
+**Table I.7 – MWI Signal Types**
+
+| <b>Data</b>                          | <b>Type</b> | <b>Persistence</b> | <b>Scope</b>       | <b>Stored by</b> | <b>Written by</b> | <b>Read by</b> | <b>Mandatory/Optional</b> |
+|--------------------------------------|-------------|--------------------|--------------------|------------------|-------------------|----------------|---------------------------|
+| UE MWI Tone Indication               | Boolean     | Non-volatile       | Per public user ID | CONFIG. SERVER   | CONFIG. SERVER    | UE             | Mandatory                 |
+| UE MWI Voice Announcement Indication | Boolean     | Non-volatile       | Per public user ID | CONFIG. SERVER   | CONFIG. SERVER    | UE             | Mandatory                 |
+| UE MWI FSK Indication                | Boolean     | Non-volatile       | Per public user ID | CONFIG. SERVER   | CONFIG. SERVER    | UE             | Mandatory                 |
+| UE MWI DTMF Indication               | Boolean     | Non-volatile       | Per public user ID | CONFIG. SERVER   | CONFIG. SERVER    | UE             | Mandatory                 |
+
+
+
+
+
+# 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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+
+
+![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
+
+**J.52**
+
+(07/96)
+
+SERIES J: TRANSMISSION OF SOUND-PROGRAMME  
+AND TELEVISION SIGNALS
+
+Digital transmission of sound-programme signals
+
+---
+
+**Digital transmission of high-quality  
+sound-programme signals using one, two or  
+three 64 kbit/s channels per mono signal (and  
+up to six per stereo signal)**
+
+ITU-T Recommendation J.52
+
+(Previously "CCITT Recommendation")
+
+---
+
+# ITU-T J-SERIES RECOMMENDATIONS **TRANSMISSION OF SOUND-PROGRAMME AND TELEVISION SIGNALS**
+
+|                                                                                                    |                  |
+|----------------------------------------------------------------------------------------------------|------------------|
+| General Recommendations                                                                            | J.1-J.9          |
+| General Recommendations concerning sound-programme transmissions                                   | J.10-J.19        |
+| Performance characteristics of sound-programme circuits                                            | J.20-J.29        |
+| Characteristics of equipment and lines used for setting up sound-programme circuits                | J.30-J.39        |
+| Characteristics of equipment for coding analogue sound-programme signals                           | J.40-J.49        |
+| <b>Digital transmission of sound-programme signals</b>                                             | <b>J.50-J.59</b> |
+| Characteristics of circuits for television transmissions                                           | J.60-J.69        |
+| Systems for television transmission over metallic lines and interconnection with radio-relay links | J.70-J.79        |
+| Digital transmission of television signals                                                         | J.80-J.89        |
+| Specific Recommendations for television transmission                                               | J.90-J.99        |
+| Transmission of signals with multiplexing of video, sound and data, and signals of new systems     | J.100-J.109      |
+| Interactive services                                                                               | J.110-J.119      |
+
+*For further details, please refer to ITU-T List of Recommendations.*
+
+## FOREWORD
+
+The ITU-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (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 (Helsinki, March 1-12, 1993).
+
+ITU-T Recommendation J.52 was revised by ITU-T Study Group 9 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on the 11th of July 1996.
+
+---
+
+## NOTE
+
+In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+© ITU 1997
+
+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
+
+|                                                                                                                              | <i>Page</i> |
+|------------------------------------------------------------------------------------------------------------------------------|-------------|
+| 0 Scope .....                                                                                                                | 1           |
+| 1 General features .....                                                                                                     | 1           |
+| 2 Network interface formats.....                                                                                             | 2           |
+| 3 Synchronization and frame alignment.....                                                                                   | 4           |
+| 4 Error control .....                                                                                                        | 12          |
+| 5 Transmission of data .....                                                                                                 | 21          |
+| Annex A – Digital transmission of medium-quality sound-programme signals using a 64 kbit/s channel (or a part thereof) ..... | 24          |
+| Appendix I – Performance of the forward error correction .....                                                               | 27          |
+
+# **SUMMARY**
+
+The system described in this Recommendation makes possible the transmission of sound signals, coded by new methods recommended by ITU-R Study Group 10 and standardized by ISO/IEC 11172-3, on 1 to 6 B-channels of the N-ISDN or on permanent connections with a 2048 kbit/s (or 1544 kbit/s) frame. In the case of transmission via the N-ISDN, Recommendation H.221 is used to aggregate up to six B-channels while maintaining the bit sequence integrity. The revised text contains clarifications that reflect experience gained in implementing the current version of this Recommendation, and a new chapter on transmission of program-associated data in the ancillary data field of the ISO frame.
+
+# **INTRODUCTION**
+
+The ISO and IEC have approved the international standard 11172-3 for the reduction of the bit rate of high-quality digital sound-programme signals. With this system, it is possible to transmit high-quality mono sound-programme signals with bit rates in the range of 64 to 192 kbit/s. Stereo signals are encoded in single bit streams with bit rates in the range 128 to 384 kbit/s. If sound signals coded by ISO/IEC 11172-3 have to be transmitted in telecommunication networks, the properties of the networks are to be taken into account. The ITU-T has approved some Recommendations which describe the structure and function of 64 kbit/s channels for audiovisual applications (Recommendation H.200 contains a list of such Recommendations).
+
+The N-ISDN allows the assembly of single channels with the bit rate of 64 kbit/s. If the bit rate is greater than 64 kbit/s (two times, three times etc.), measures are necessary to maintain the bit sequence. The equipment described in the following enables the transmission of source-coded sound signals on channels of N-ISDN or on connections with a 2048 kbit/s (or 1544 kbit/s) frame.
+
+
+
+# DIGITAL TRANSMISSION OF HIGH-QUALITY SOUND-PROGRAMME SIGNALS USING ONE, TWO OR THREE 64 kbit/s CHANNELS PER MONO SIGNAL (AND UP TO SIX PER STEREO SIGNAL)
+
+*(revised in 1996)*
+
+# 0 Scope
+
+The ITU-R Recommendation BS.1115 recommends, based on extensive tests carried out by ITU-R Study Group 10 for different applications of the transmission in a broadcast chain (contribution, distribution, emission, commentary), the bit rate reduction system according to ISO/IEC 11172-3. The encoding layers and bit rates (per mono channel) recommended by ITU-R SG 10 depend on the application and are in the range of 120 - 180 kbit/s using Layer II, except for commentary where 60 kbit/s using Layer III may be used. For details, see ITU-R BS.1115.
+
+For transmission of high-quality sound programmes and associated data it is desirable to use standardized 64 kbit/s channels or multiples thereof. This Recommendation defines formatter and reformatter for the transport of the bit rate reduced audio signals according to ISO/IEC 11172-3 and associated data on these standardized 64 kbit/s channels. The bit stream to be transmitted on 64 kbit/s channels could be protected optionally by means of error-correction measures.
+
+The ITU-R has not (before the end of 1995) made any recommendation for the use of the ISO/IEC 13818-3 *lower sampling frequencies*. **If and only if** the extension to *lower sampling frequencies* is to be implemented, the provisions in Annex A shall apply. The implementation of the *lower sampling frequency* modes is in no way mandatory as they inherently limit the bandwidth, and would therefore not permit the high-quality criteria to be met.
+
+## 1 General features
+
+### 1.1 Purpose of the equipment
+
+The purpose of the equipment is to process a bit rate reduced high-quality sound-programme signal for transmission on standardized 64 kbit/s channels. For this purpose, it is appropriate that the source encoder and the multiplexer form a unit with an output to the line interface (see Figure 1).
+
+![Block diagram showing the connection between an ISO 11172-3 encoder, a Mux, a Line interface, and a Transmission network. Inputs include Sound and Ancillary data. Control signals are shown between the encoder and Mux, and Clock signals between the Line interface and Transmission network.](e2c1c672349c10dccb2563eff6d8260e_img.jpg)
+
+```
+
+graph LR
+    Sound[Sound] --> Encoder[ISO 11172-3 encoder]
+    Ancillary[Ancillary data] --> Encoder
+    Encoder --> Mux[Mux]
+    Encoder -- Control --> Mux
+    Mux --> Line[Line interface]
+    Line -- Clock --> Network[Transmission network]
+    Network -- Clock --> Line
+    
+```
+
+T0902350-94/d01
+
+Block diagram showing the connection between an ISO 11172-3 encoder, a Mux, a Line interface, and a Transmission network. Inputs include Sound and Ancillary data. Control signals are shown between the encoder and Mux, and Clock signals between the Line interface and Transmission network.
+
+FIGURE 1/J.52  
+Connection between encoder, multiplexer and line interface
+
+### 1.2 Incoming signals (PCM level)
+
+The source encoder provides a bit stream according to ISO Standard 11172-3 (Layer I, Layer II or Layer III). Layer I is not recommended for broadcast applications, the block structure of Layers II and III with the block length 24 ms (in case of 48 kHz sampling frequency) is shown in Figure 2.
+
+![Figure 2/J.52: Block structure of the Layer II and Layer III bit streams. Diagram (a) shows the Layer II bit stream with fields: Header, CRC (optional), Bit allocation, SCF SI, Scale factors, Sub-band samples, and Ancillary data, all within a 24 ms block. Diagram (b) shows the Layer III bit stream with fields: Header (32 bits), CRC (optional) (16 bits), Side-info (Mono 136 bits else 256 bits), and Main data spectral values and ancillary data (length coded in side-info), all within a 24 ms block.](990567efebf979be51f56d1150012c9d_img.jpg)
+
+**a) Block structure of the Layer II bit stream**
+
+|        |                |                |        |               |                  |                |
+|--------|----------------|----------------|--------|---------------|------------------|----------------|
+| Header | CRC (optional) | Bit allocation | SCF SI | Scale factors | Sub-band samples | Ancillary data |
+|--------|----------------|----------------|--------|---------------|------------------|----------------|
+
+24 ms
+
+**b) Block structure of the Layer III bit stream**
+
+|        |                |           |                                              |
+|--------|----------------|-----------|----------------------------------------------|
+| Header | CRC (optional) | Side-info | Main data spectral values and ancillary data |
+|--------|----------------|-----------|----------------------------------------------|
+
+32 bits    16 bits    Mono 136 bits else 256 bits    Length coded in side-info
+
+24 ms
+
+T0903180-95/d02
+
+Figure 2/J.52: Block structure of the Layer II and Layer III bit streams. Diagram (a) shows the Layer II bit stream with fields: Header, CRC (optional), Bit allocation, SCF SI, Scale factors, Sub-band samples, and Ancillary data, all within a 24 ms block. Diagram (b) shows the Layer III bit stream with fields: Header (32 bits), CRC (optional) (16 bits), Side-info (Mono 136 bits else 256 bits), and Main data spectral values and ancillary data (length coded in side-info), all within a 24 ms block.
+
+FIGURE 2/J.52
+
+If possible, this bit stream has to be transmitted unchanged. In most cases, this is impossible for the following reasons:
+
+- additional framing bits are necessary for the transmission on the ISDN B-channels;
+- if it is necessary to include error control in order to correct the bit errors, another coding hierarchy level has to be used.
+
+Table 1 gives all frame lengths defined in ISO 11172-3.
+
+If the padding bit in the header is set, the frame contains an additional slot (1 byte for Layers II and III, 4 bytes for Layer I). The bit rate is encoded with 4 bits (bit rate index). The coding of the bit rate is different for the three layers (see ISO 11172-3). Layer I and sampling frequency 44.1 kHz are not recommended for broadcast applications.
+
+## 2 Network interface formats
+
+There is a distinction between dial-up connections (ISDN) and permanent connections. This distinction consists of the different routing of several B-channels constituting a virtual sound channel of more than 64 kbit/s, which requires a delay difference compensation in case of dial-up connections.
+
+Two transmission formats are required:
+
+- transmission of *one* mono/stereo signal using one to six 64 kbit/s channels or a single H<sub>0</sub> channel in a switched ISDN network;
+- transmission of *one or more* mono/stereo signals using, for example, H<sub>0</sub> or H<sub>1</sub> channels for permanent connections.<sup>1)</sup>
+
+<sup>1)</sup> For transmission of *one* mono/stereo signal at a bit rate of 1 to 6 × 64 kbit/s on permanent connections, the X.21 leased circuit option can be used. In this case, H.221 framing is optional.
+
+TABLE 1/J.52
+
+### **Possible frame lengths in bytes (without padding)**
+
+| Sampling Frequency (Hz) | 32 000 |      |      | 44 100 |      |      | 48 000 |      |     |
+|-------------------------|--------|------|------|--------|------|------|--------|------|-----|
+| Layer                   | I      | II   | III  | I      | II   | III  | I      | II   | III |
+| Bit rate (bit/s)        |        |      |      |        |      |      |        |      |     |
+| 32 000                  | 48     | 144  | 144  | 32     | 104  | 104  | 32     | 96   | 96  |
+| 40 000                  | –      | –    | 180  | –      | –    | 130  | –      | –    | 120 |
+| 48 000                  | –      | 216  | 216  | –      | 156  | 156  | –      | 144  | 144 |
+| 56 000                  | –      | 252  | 252  | –      | 182  | 182  | –      | 168  | 168 |
+| 64 000                  | 96     | 288  | 288  | 68     | 208  | 208  | 64     | 192  | 192 |
+| 80 000                  | –      | 360  | 360  | –      | 261  | 261  | –      | 240  | 240 |
+| 96 000                  | 144    | 432  | 432  | 104    | 313  | 313  | 96     | 288  | 288 |
+| 112 000                 | –      | 504  | 504  | –      | 365  | 365  | –      | 336  | 336 |
+| 128 000                 | 192    | 576  | 576  | 136    | 417  | 417  | 128    | 384  | 384 |
+| 160 000                 | 240    | 720  | 720  | 172    | 522  | 522  | 160    | 480  | 480 |
+| 192 000                 | 288    | 864  | 864  | 208    | 626  | 626  | 192    | 576  | 576 |
+| 224 000                 | 336    | 1008 | 1008 | 240    | 731  | 731  | 224    | 672  | 672 |
+| 256 000                 | 384    | 1152 | 1152 | 276    | 835  | 835  | 256    | 768  | 768 |
+| 288 000                 | 432    | –    | –    | 312    | –    | –    | 288    | –    | –   |
+| 320 000                 | 480    | 1440 | 1440 | 348    | 1044 | 1044 | 320    | 960  | 960 |
+| 352 000                 | 528    | –    | –    | 380    | –    | –    | 352    | –    | –   |
+| 384 000                 | 576    | 1728 | –    | 416    | 1253 | –    | 384    | 1152 | –   |
+| 416 000                 | 624    | –    | –    | 452    | –    | –    | 416    | –    | –   |
+| 448 000                 | 672    | –    | –    | 484    | –    | –    | 448    | –    | –   |
+
+NOTE – A dash “–” in the table means that the combination of sampling frequency, bit rate and layer is not specified in ISO/IEC 11172-3.
+
+### 2.1 Dial-up connections (switched ISDN network)
+
+According to Recommendation I.412 the following possibilities exist:
+
+- a) *B-channel interface structures*
+  - i) basic interface structure: 2 B-channels + 1 D-channel (16 kbit/s);
+  - ii) primary rate B-channel interface structures:
+    - 1544 kbit/s primary rate: 23 B + 1 D (64 kbit/s);
+    - 2048 kbit/s primary rate: 30 B + 1 D (64 kbit/s).
+- b) *H-channel interface structures*
+  - i) primary rate interface H<sub>0</sub>-channel structures:
+    - 1544 kbit/s primary rate: 4 H<sub>0</sub>;  
+3 H<sub>0</sub> + D.
+    - 2048 kbit/s primary rate: 5 H<sub>0</sub> + D.
+
+For the following parameters, appropriate means have to be provided:
+
+- clock synchronization between source coder and network;
+- time synchronization (delay difference compensation) between several B-channels.
+
+### 2.2 Permanent connections
+
+2048 kbit/s or 1544 kbit/s signals are used. Framing is according to Recommendation G.704.
+
+The following parameters need consideration:
+
+- clock synchronization between source coder and network;
+- octet sequence integrity within the same frame;
+- time slot allocation.
+
+## 3 Synchronization and frame alignment
+
+### 3.1 Dial-up connections
+
+For all 64 kbit/s channels of the basic interface structure in dial-up connections, the framing according to Recommendation H.221, in conjunction with Recommendation H.242, should be used. With the use of the H.221 framing there is a possibility to achieve both clock synchronization and time synchronization between up to six B-channels. This is permanently provided, also in case of a change of the routing during the transmission.
+
+Furthermore, the addition of H.221 framing to dial-up connections ( $H_0$  or 1 to 6 B-channels) provides a control channel harmonized with other N-ISDN audiovisual equipment.
+
+The procedure for **initialization** of the communication at the start of a call shall be according to Recommendation H.242, except that, if there is no requirement for intercommunication with 3 kHz speech terminals, it is not necessary to transmit G.711 audio during the period until Sequence A is completed. The capabilities to be transmitted during Sequence A include appropriate values from Table A.2/H.221, and a single command from that table introduces a mode switch to the required sound transmission mode.
+
+Particular attention is drawn to clause 13/H.242 for the cases of transmission within a restricted network (multiple 56 kbit/s channels) and of interworking between unrestricted and restricted networks. Terminals on both types of network shall transmit within their capability sets the relevant values from attribute (110) of Table A.1/H.221.
+
+#### 3.1.1 Basic interface structure
+
+To achieve the synchronization according to Recommendation H.221, an overhead [consisting of a Frame Alignment Signal (FAS) and Bit Rate Allocation Signal (BAS)] of 1.6 kbit/s is required per 64 kbit/s channel or in the first time slot of an  $H_0$  channel.
+
+For the transmission of bit rate reduced high-quality sound signals, Recommendation H.221 has been extended.
+
+#### 3.1.2 Realization of bit rates which are not explicitly listed in the bit rate table of the ISO/IEC 11172-3 Standard
+
+Figure 3 describes the different sections of the transmission system. The network provides data channels each with 64 kbit/s. If H.221 framing and an additional error protection is applied, the full channel capacity cannot be used by the ISO 11172-3 encoder for audio data.
+
+The ISO/IEC 11172-3 bit stream is sub-divided in audio frames corresponding to a sequence of 384 PCM audio samples for Layer I and 1152 PCM audio samples for Layers II and III. The audio frame length (see Table 1) is dependent on the bit rate index, the sampling frequency and the status of the padding bit, an information that is given in the audio frame header. The ISO/IEC 11172-3 Standard allows for 14 different, explicitly listed bit rates, indicated by the so-called bit rate index value. An additional format, the “free format”, i.e. a user-defined audio frame length, can be chosen by using the bit rate index “0000”.
+
+Two methods may be used in order to realize those bit rates that are not explicitly listed in the bit rate tables of the ISO/IEC 11172-3 Standard. These methods are:
+
+- using the ancillary data field (recommended for Layers I and II);
+- dynamic bit rate switching (recommended for Layer III).
+
+The use of free format is not recommended.
+
+![Block diagram of a transmission system with transport format and optional error control. The diagram shows a sequence of blocks: ISO 11172-3 encoder, Error correction encoding (optional), Formatter, H.221/H.242 encoder, Network, H.221/H.242 decoder, Reformatter, Error correction decoding (optional), and ISO 11172-3 decoder. Arrows indicate the flow of data and control signals between these blocks and a central Network block. Three horizontal lines at the bottom indicate different levels of data: PCM level (uncoded audio data), ISO 11172-3 coded level, and Transport level with or without error correction. A label 'Network level' is also present.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg)
+
+```
+
+graph LR
+    Input --> ISO_Enc[ISO 11172-3 encoder]
+    ISO_Enc --> EC_Enc[Error correction encoding optional]
+    EC_Enc --> Form[Formatter]
+    Form --> H_Enc[H.221/H.242 encoder]
+    H_Enc --> Net[Network]
+    Net --> H_Dec[H.221/H.242 decoder]
+    H_Dec --> Ref[Reformatter]
+    Ref --> EC_Dec[Error correction decoding optional]
+    EC_Dec --> ISO_Dec[ISO 11172-3 decoder]
+    ISO_Dec --> Output
+    
+    %% Control/Feedback loops
+    EC_Enc -.-> ISO_Enc
+    H_Enc -.-> EC_Enc
+    H_Dec -.-> EC_Dec
+    EC_Dec -.-> ISO_Dec
+
+```
+
+The diagram illustrates a transmission system architecture. The data flow proceeds from left to right through the following components:
+
+- ISO 11172-3 encoder**: Takes input and produces coded data.
+- Error correction encoding (optional)**: Adds error correction to the coded data.
+- Formatter**: Prepares the data for transport.
+- H.221/H.242 encoder**: Encapsulates the formatted data for network transmission.
+- Network**: The central transmission medium, with associated **Network level** signaling.
+- H.221/H.242 decoder**: Decapsulates data from the network.
+- Reformatter**: Adjusts the data format for further processing.
+- Error correction decoding (optional)**: Detects and corrects errors in the data.
+- ISO 11172-3 decoder**: Decodes the final output.
+
+Control and data levels are indicated by horizontal lines at the bottom:
+
+- PCM level (uncoded audio data)**: Spans from the input to the final output.
+- ISO 11172-3 coded level**: Spans from the ISO 11172-3 encoder to the ISO 11172-3 decoder.
+- Transport level with/or without error correction**: Spans from the Formatter to the Reformatter.
+
+T0903160-95/d03
+
+Block diagram of a transmission system with transport format and optional error control. The diagram shows a sequence of blocks: ISO 11172-3 encoder, Error correction encoding (optional), Formatter, H.221/H.242 encoder, Network, H.221/H.242 decoder, Reformatter, Error correction decoding (optional), and ISO 11172-3 decoder. Arrows indicate the flow of data and control signals between these blocks and a central Network block. Three horizontal lines at the bottom indicate different levels of data: PCM level (uncoded audio data), ISO 11172-3 coded level, and Transport level with or without error correction. A label 'Network level' is also present.
+
+FIGURE 3/J.52  
+**Transmission system with transport format and optional error control**
+
+##### 3.1.2.1 Using the ancillary data field (recommended for Layers I and II)
+
+The last field in a ISO/IEC 11172-3 frame is the “ancillary data” field, which consists of all bits that are not used for audio. A minimum length of this field can be guaranteed by constraining the bit allocation in the encoder. The desired bit rate can be obtained by selecting a bit rate higher than the desired bit rate, taking into account the constraining of the ISO/IEC Standard, and stripping off a number of bytes from each frame. The resulting frames are hereafter called “shortened frames”. After transmission, the correct number of zero-valued bytes is inserted again, in order to reconstitute compliant MPEG audio frames, hereafter called “long frames”.
+
+In the following, an exact method is described to obtain the length of the short frame for each ISO/IEC 11172-3 frame, given a certain desired bit rate and sampling frequency. An ISO/IEC 11172-3 frame always consists of an integer number of slots, being one byte in Layer II and four bytes in Layer I. The number of slots in a short frame has to be calculated using the following formulae:
+
+$$\text{Layer II: } N = 144 \frac{\text{desired bit rate}}{\text{sampling frequency}}$$
+
+$$\text{Layer I: } N = 12 \frac{\text{desired bit rate}}{\text{sampling frequency}}$$
+
+If the calculation above yields a non-integer number, the result is truncated, and padding is required. In this case, the number of slots in a frame will vary between  $N$  and  $N + 1$ . The padding bit is set to “0” if the number of slots equals  $N$ , and otherwise to “1”.
+
+The padding should be applied to the bit stream such that the accumulated length of the coded frames, after a certain number of audio frames, does not deviate by more than  $(+0, -1 \text{ slot})$  from the following computed value, where *bit rate* is the desired bit rate:
+
+$$\text{Accumulated frame length} = \sum_{\text{first frame}}^{\text{current frame}} \frac{(\text{frame size})(\text{bit rate})}{\text{sampling frequency}}$$
+
+where frame size equals 384 for Layer I, and 1152 for Layer II.
+
+The following method, described in C-syntax, can be used to determine whether or not to use padding:
+
+for 1st audio frame:
+
+rest = 0
+
+padding = no;
+
+for each subsequent audio frame:
+
+if (Layer = 1) dif = (12 \* bit rate) % sampling frequency;
+
+else dif = (144 \* bit rate) % sampling frequency;
+
+rest = rest - dif;
+
+if (rest < 0) {
+
+padding = yes;
+
+rest = rest + sampling frequency;
+
+}
+
+else padding = no;
+
+If the padding bit is modified (P1→P2 in Figure 4), the ISO-CRC has to be recalculated.
+
+Note that the resulting bit stream of short frames is very similar to an ISO/IEC 11172-3 free format bit stream. Exceptions are the value of the bit rate index (which is “0000” in free format mode) and the bit allocation tables for some combinations of sampling frequency and bit rate. It should be noted that in an integrated implementation of
+
+an MPEG audio encoder, formatter and H.221 encoder, it is possible to apply a special MPEG audio encoder that directly generates the short frames.
+
+At the receiving end, the output of the H.221 decoder will be the short frames. In order to regenerate long frames, the following procedure has to be applied. The number of slots and the padding sequence of the long frames have to be calculated in the same way as previously described for the short frames, but now with the bit rate which corresponds to the bit rate index in the ISO/IEC 11172-3 header. The padding bit in the short frames has to be overwritten with the calculated padding bit value for the long frame (this value will always be zero for 32 and 48 kHz sampling frequency), and the short frame has to be filled up with zero-valued slots to the full length of the long frame.
+
+If the padding bit has to be changed (P2→P3 in Figure 4), the following procedure has to be applied:
+
+- if the ISO-CRC verification shows no errors, the ISO-CRC has to be recalculated, based upon the padding bit of the regenerated long frame;
+- otherwise the ISO-CRC has to be transmitted as received.
+
+It should be noted that in an integrated implementation of H.221 decoder, reformatter and ISO decoder, it might not be necessary to rebuild the long frames, but to apply a special MPEG audio decoder that works directly on the short frames. If ancillary data, such as Programme Associated Data (PAD), error control data or scale factor CRCs, have to be transmitted along with the audio data, the bit allocation of the encoder has to be further constrained as to allow insertion of this data in the short frames.
+
+Figure 4 shows how not explicitly listed bit rates can be derived out of a compliant MPEG frame.
+
+##### 3.1.2.2 Dynamic bit rate switching (recommended for Layer III)
+
+For Layer III the audio frame length can be changed dynamically from frame to frame. Using this method, on average additional bit rates that are not listed in the bit rate table of the ISO/IEC 11172-3 Standard are supported. The sequence of frames with different bit rates called switching period (P) which is necessary to realize the required bit rate has to be determined in the encoder. Hereby, the following formula has to be considered:
+
+$$\text{Bit rate/kbit/s} = \text{Average frame length/bits} \times \text{Sampling frequency/kHz}/1152$$
+
+For example, for a bit rate of 62.4 kbit/s and a sampling frequency of 48 kHz, a sequence of one frame containing 168 bytes = 1344 bits (corresponding to a bit rate of 56 kbit/s) and four frames containing 192 bytes (corresponding to a bit rate of 64 kbit/s) has to be used. This sequence results in an average frame length of 187.2 bytes = 1497.6 bits. The switching period (P), the length of a short frame (L1) and a long frame (L2) is shown in Table 3. I1 and I2 are the number of frames with the length L1 or L2 respectively within a switching period P. In case of error control modes 2 and 3, the sum of the bits used for the H.221 coding and the error control has to be taken into account for the average bit rate.
+
+If a long frame is used, some bits can be stored in the internal buffer and used for the next frame if necessary, to achieve a constant average bit rate for the encoding.
+
+Example: Average bit rate 62.4 kbit/s, 48 kHz sampling frequency.
+
+| Bit rate index | Bits used for encoding | Bits put into/taken from the buffer |
+|----------------|------------------------|-------------------------------------|
+| “64 000”       | 1497                   | 39                                  |
+| “64 000”       | 1497                   | 39                                  |
+| “64 000”       | 1498                   | 38                                  |
+| “64 000”       | 1498                   | 38                                  |
+| “56 000”       | 1498                   | –154                                |
+
+A nearly arbitrary switching sequence has to be taken into account, especially in asynchronous operating mode.
+
+![Block diagram showing the ancillary data field method for realizing not explicitly listed bit rate. It includes stages: PCM Signal -> MPEG Encoder -> Formatter -> H.221 Encoder -> Network connection -> H.221 Decoder -> Reformatter -> MPEG Decoder -> PCM Signal. Bit rate control signals are shown between the stages and the frame structure diagram.](b9ecbc3baefab13719e000faa6e0c7eb_img.jpg)
+
+The diagram illustrates the flow of data through various encoding and decoding stages, with corresponding MPEG frame structures shown on the right.
+
+- PCM Signal** enters the **MPEG Encoder**.
+- The **MPEG Encoder** outputs an **ISO Bit rate according to bit rate index**.
+- This signal goes to the **Formatter**, which also receives a **Desired bit rate** input.
+- The **Formatter** outputs to the **H.221 Encoder**.
+- The **H.221 Encoder** outputs to the **Network connection**.
+- From the **Network connection**, the signal goes to the **H.221 Decoder**.
+- The **H.221 Decoder** outputs a **Desired bit rate** signal to the **Reformatter**.
+- The **Reformatter** outputs an **ISO Bit rate according to bit rate index** to the **MPEG Decoder**.
+- The **MPEG Decoder** outputs the final **PCM Signal**.
+
+On the right, the frame structures are shown:
+
+- Compliant MPEG Frame (Long Frame)**: Contains a **Header** (B, P<sub>1</sub>), **Available for Audio Data**, and **Ancillary Data**.
+- Non Compliant MPEG Frame (Shortened Frame)**: Contains a **Header** (B, P<sub>2</sub>) and **Available for Audio Data**. The **Ancillary Data** section is labeled **Slots to be stripped off**.
+- Compliant MPEG Frame (Long Frame)**: Contains a **Header** (B, P<sub>3</sub>), **Available for Audio Data**, and **Re-inserted Slots**.
+
+Control signals and padding bits are indicated:
+
+- Padding bit 1** and **Bit rate index** are shown in the header of the first frame.
+- Padding bit 2** and **Bit rate index (unchanged)** are shown in the header of the second frame.
+- Padding bit 3** and **Bit rate index (unchanged)** are shown in the header of the third frame.
+
+T0903170-95/d04
+
+Block diagram showing the ancillary data field method for realizing not explicitly listed bit rate. It includes stages: PCM Signal -> MPEG Encoder -> Formatter -> H.221 Encoder -> Network connection -> H.221 Decoder -> Reformatter -> MPEG Decoder -> PCM Signal. Bit rate control signals are shown between the stages and the frame structure diagram.
+
+FIGURE 4/J.52  
+**Ancillary data field method for realizing not explicitly listed bit rate**  
+(Mandatory for J.52)
+
+##### 3.1.2.3 Example
+
+Tables 2 and 3 list details for an adaption of the explicitly listed bit rates according to ISO/IEC 11172-3 to the available channel bit rate for the methods "Using the ancillary data field" and "Dynamic bit rate switching". The contents of these tables are:
+
+- *Channels:* Number of used 64 kbit/s channels.
+- *Mode:* Inband H.221 framing is used within each sub-channel.  
+Inband 56k H.221 framing is used within each 56 kbit/s channel.
+- *Desired bit rate:* Data rate available for the ISO 11172-3 audio data.
+
+The following values are given in Table 2:
+
+- L Length of long frame (as defined in ISO/IEC 11172-3);
+- S Length of a shortened frame.
+
+TABLE 2/J.52
+
+#### **Adaption of the explicitly listed bit rates according to ISO/IEC 11172-3 to the desired bit rate (examples for Layer II)**
+
+| Channels | Mode       | Desired data rate | Sampling frequency |      |          |      |        |      |
+|----------|------------|-------------------|--------------------|------|----------|------|--------|------|
+|          |            |                   | 32 kHz             |      | 44.1 kHz |      | 48 kHz |      |
+|          |            |                   | L                  | S    | L        | S    | L      | S    |
+| 1        | inband     | 62 400            | 192                | 187  | 208      | 203  | 288    | 280  |
+| 2        | inband     | 124 800           | 384                | 374  | 417      | 407  | 576    | 561  |
+| 3        | inband     | 187 200           | 576                | 561  | 626      | 611  | 864    | 842  |
+| 4        | inband     | 249 600           | 768                | 748  | 835      | 815  | 1152   | 1123 |
+| 5        | inband     | 312 000           | 960                | 936  | 1044     | 1018 | 1440   | 1404 |
+| 6        | inband     | 374 400           | 1152               | 1123 | 1253     | 1222 | 1728   | 1684 |
+| 2        | inband 56k | 108 800           | 336                | 326  | 365      | 355  | 504    | 489  |
+
+The following values are given in Table 3:
+
+- L1 Nominal frame length for a short frame (as defined in ISO/IEC 11172-3).
+- L2 Nominal frame length for a long frame (as defined in ISO/IEC 11172-3).
+- I1 Number of frames using L1.
+- I2 Number of frames using L2.
+- P Switching period of frame length.
+- dL Average frame length.
+
+Table 3 is valid for a sampling frequency of 48 kHz.
+
+### 3.2 Transmission on permanent connections
+
+The structure of a 2048 kbit/s frame consists of 32 Time Slots (TS) with a capacity of 64 kbit/s each. The structure of a 1544 kbit/s frame consists of 24 TS, also with the capacity of 64 kbit/s per TS.
+
+TABLE 3/J.52
+
+#### **Adaptation of the explicitly listed bit rates according to ISO/IEC 11172-3 to the desired bit rate (examples for Layer III)**
+
+| Channels | Mode      | Desired data rate | L1 (byte) | I1 | L2 (byte) | I2 | P  | dL    |
+|----------|-----------|-------------------|-----------|----|-----------|----|----|-------|
+| 1        | inband    | 62 400            | 168       | 1  | 192       | 4  | 5  | 187.2 |
+| 2        | inband    | 124 800           | 336       | 1  | 384       | 4  | 5  | 374.4 |
+| 3        | inband    | 187 200           | 480       | 3  | 576       | 17 | 20 | 561.6 |
+| 4        | inband    | 249 600           | 672       | 1  | 768       | 4  | 5  | 748.8 |
+| 5        | inband    | 312 000           | 768       | 1  | 960       | 7  | 8  | 936   |
+| 2        | inband 56 | 108 800           | 288       | 1  | 336       | 4  | 5  | 326.4 |
+
+TS 0 is used for frame alignment. For 2 Mbit/s frames, TS 16 is reserved for signalling and other network purposes. In case of channel-associated signalling, transmission of low speed data channels (associated with sound channels) in TS 16 is possible.
+
+In case of error control modes 1, 2 and 3, capacity for redundancy is necessary. This capacity either:
+
+- is taken from the ancillary data field (refer to 3.1.2.1); or
+- is provided by dynamic bit rate switching (refer to 3.1.2.2).
+
+In 2 Mbit/s (or 1.5 Mbit/s) connections there are two operation modes, a flexible multiplex mode and a fixed multiplex mode. In the flexible multiplex mode only time slot TS 1 has the H.221 framing, all other TS without are framing and can transmit the full capacity of 64 kbit/s. In the fixed multiplex mode all TS can transmit the full capacity of 64 kbit/s without H.221 framing. The channels are allocated in a fixed order.
+
+#### 3.2.1 Flexible multiplex
+
+In this flexible multiplex mode the Multiple Byte Extension (MBE) is used (see Recommendation H.221). TS 1 has a frame structure according to Recommendation H.221. It is not to be used for the transmission of sound signals, but contains FAS and BAS and can be used for the transmission of one G.722 channel and/or Low Speed Data (LSD). The audio signals are transmitted in the TS 2 to 15 and 17 to 31 for 32 TS systems, and in the TS 2 to 23 for 24 TS systems.
+
+Each TS except TS 1 is an unframed 64 kbit/s channel with full capacity, which means it is possible to transmit:
+
+- 64 kbit/s in one TS;
+- 128 kbit/s in two TS;
+- 192 kbit/s in three TS, etc.
+
+In case of transmission of more than 64 kbit/s, two or more TS constitute a virtual channel.
+
+In Recommendation H.221, the details for control and signalling purposes (capability exchange, command exchange) are indicated.
+
+#### 3.2.2 Fixed multiplex
+
+The fixed multiplex mode is established via 2048 kbit/s frames according to Recommendation G.704 and in principle the time slots could be allocated individually.
+
+In the case of transmission of more than 64 kbit/s, two or more time slots constitute a virtual channel.
+
+If the frame is in accordance with Recommendation G.735 or Recommendation G.737, the following time slot allocations are recommended (see Tables 4-1 and 4-2):
+
+TABLE 4-1/J.52
+
+|   | A      | B      | C      | D       | E       |
+|---|--------|--------|--------|---------|---------|
+| 1 | 1 – 17 | 4 – 20 | 7 – 23 | 10 – 26 | 13 – 29 |
+| 2 | 2 – 18 | 5 – 21 | 8 – 24 | 11 – 27 | 14 – 30 |
+| 3 | 3 – 19 | 6 – 22 | 9 – 25 | 12 – 28 | 15 – 31 |
+
+NOTE – The fifteen possible 128 kbit/s channels in a 2048 kbit/s stream are numbered A1 to E3. Preferably the channel pairs A1-A2, A2-A3, A3-B1, ... E2-E3 should be used for stereophonic transmission, or as a 256 kbit/s channel.
+
+TABLE 4-2/J.52
+
+|   | A            | B            | C            | D            | E            |
+|---|--------------|--------------|--------------|--------------|--------------|
+| a | 1 – 2 – 3    | 4 – 5 – 6    | 7 – 8 – 9    | 10 – 11 – 12 | 13 – 14 – 15 |
+| b | 17 – 18 – 19 | 20 – 21 – 22 | 23 – 24 – 25 | 26 – 27 – 28 | 29 – 30 – 31 |
+
+NOTE – The ten possible 192 kbit/s channels in a 2048 kbit/s stream are numbered Aa to Eb. Preferably the channel pairs Aa-Ab and Ba-Bb and Ca-Cb and Da-Db and Ea-Eb should be used for stereophonic transmission, or as a 384 kbit/s channel.
+
+If the frame is in accordance with Recommendation G.738, the following time slot allocations are recommended for establishing 320 kbit/s channels (see Table 4-3):
+
+TABLE 4-3/J.52
+
+| A                    | B                     | C                         | D                         | E                         | F                         |
+|----------------------|-----------------------|---------------------------|---------------------------|---------------------------|---------------------------|
+| 1 – 2 – 3 –<br>4 – 5 | 6 – 7 – 8 –<br>9 – 10 | 11 – 12 – 13 –<br>14 – 15 | 17 – 18 – 19 –<br>20 – 21 | 22 – 23 – 24 –<br>25 – 26 | 27 – 28 – 29 –<br>30 – 31 |
+
+### 3.3 Synchronization of the sampling frequencies to the clock frequency
+
+In real-time transmission systems, proper synchronization of encoder and decoder is a very important topic. A synchronous or an asynchronous operating mode can be used.
+
+#### 3.3.1 Synchronous operating mode
+
+Usually, the transmission system provides the master clock at both sides, i.e. the sampling clock at the input and output of the system is synchronized by the transmission clock (see Figure 5). Therefore, with digital audio inputs, either the audio source has to be synchronized to the transmission clock or a sample rate converter has to be used.
+
+#### 3.3.2 Asynchronous operating mode
+
+The sampling clock of the audio input is asynchronous to the network clock. The codec has to adapt the ratio between sampling frequency and bit rate to the network clock.
+
+![Block diagram of synchronous operating mode. An input signal (represented by a sine wave symbol) enters a 'Sampling Rate Converter'. The output of the converter goes to an 'Encoder'. A 'PLL' block is connected to the 'Sampling Rate Converter' and the 'Encoder'. A 'Network clock' is connected to the 'PLL' and the 'Encoder'. The 'Encoder' outputs 'Clock' and 'Data' signals to a 'Decoder'. The 'Decoder' is connected to a 'PLL' block, which is also connected to an 'AES/EBU Output' block. The 'AES/EBU Output' block is labeled T0902270-94/d05.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg)
+
+Block diagram of synchronous operating mode. An input signal (represented by a sine wave symbol) enters a 'Sampling Rate Converter'. The output of the converter goes to an 'Encoder'. A 'PLL' block is connected to the 'Sampling Rate Converter' and the 'Encoder'. A 'Network clock' is connected to the 'PLL' and the 'Encoder'. The 'Encoder' outputs 'Clock' and 'Data' signals to a 'Decoder'. The 'Decoder' is connected to a 'PLL' block, which is also connected to an 'AES/EBU Output' block. The 'AES/EBU Output' block is labeled T0902270-94/d05.
+
+FIGURE 5/J.52  
+Synchronous operating mode
+
+With Layer III, the use of any data rate is possible. Therefore, a completely asynchronous operation is feasible. The encoder counts the number of data bits that have been transmitted within a certain time interval and compares it with the target number (the nominal data rate, multiplied by the time interval). If the actual number of data bits is too small, the encoder has to use a frame with a smaller data rate for the next frame and vice versa. Using a similar approach, the decoder controls its sampling frequency to set it to the same value as in the encoder (see Figure 6).
+
+If H.221 framing is applied, asynchronous operating mode is also possible for Layer II using padding (except the data rate 320 kbit/s).
+
+![Block diagram of asynchronous operating mode. An input signal (represented by a sine wave symbol) enters an 'Encoder'. The 'Encoder' outputs 'Clock' and 'Data' signals to a 'Decoder'. A 'Network clock' is connected to the 'Encoder' and the 'Decoder'. The 'Decoder' is connected to a 'Digital Controlled Oscillator', which is also connected to an 'AES/EBU Output' block. The 'AES/EBU Output' block is labeled T0902280-94/d06.](9b9d2abd741ed4bafe7f78f89961c663_img.jpg)
+
+Block diagram of asynchronous operating mode. An input signal (represented by a sine wave symbol) enters an 'Encoder'. The 'Encoder' outputs 'Clock' and 'Data' signals to a 'Decoder'. A 'Network clock' is connected to the 'Encoder' and the 'Decoder'. The 'Decoder' is connected to a 'Digital Controlled Oscillator', which is also connected to an 'AES/EBU Output' block. The 'AES/EBU Output' block is labeled T0902280-94/d06.
+
+FIGURE 6/J.52  
+Asynchronous operating mode
+
+## 4 Error control
+
+The use of the ISO CRC in the source coded audio signal is mandatory for the transmission application. (The CRC bits allow error detection in the header and in the most important parts of the side information.)
+
+If Recommendation H.221 is applied, the CRC-4 procedure has to be used. Both ISO CRC and CRC-4 can be utilized to detect errors, but not to correct them. If necessary, error correction can be applied in addition.
+
+The following four error control modes are provided:
+
+- Mode 0: only ISO CRC
+- Mode 1: unequal error control typical redundancy  $r \approx 1.0\%$
+- Mode 2: low equal error control typical redundancy  $r \approx 2.5\%$
+- Mode 3: high equal error control typical redundancy  $r \approx 10\%$
+
+The error control is performed by:
+
+- error correction by a Reed-Solomon code;
+- error concealment with the CRC-16.
+
+If the Reed-Solomon code (RS code) is overloaded, then the error concealment based on the ISO CRC-16 should be applied. The error control modes 1, 2, 3 use the same coding scheme.
+
+- Symbol length:  $m = 8$  bits (1 byte)
+- Codeword length:  $N$  byte (variable)
+- Code dimension:  $K = N - 4$  bytes
+- Field generator polynomial:  $f(x) = x^8 + x^4 + x^3 + x^2 + 1$
+- Code generator polynomial: 
+$$g(x) = \prod_{i=1}^4 (x + \alpha^{125+i})$$
+
+$$= x^4 + \alpha^{201}x^3 + \alpha^{246}x^2 + \alpha^{201}x + 1$$
+
+A data byte  $(d_7, d_6, \dots, d_1, d_0)$  is identified with the element:
+
+$$d_7\alpha^7 + d_6\alpha^6 + \dots + d_1\alpha + d_0 \text{ in GF}(256).$$
+
+For the calculation of RS-code and transmission of redundancy, the most significant byte and the most significant bit of a byte ( $d_7$ ) are the first transmitted.
+
+### 4.1 Unequal error correction (only Layer II)
+
+In any frame, error correction applies to:
+
+- bits 16...31 of the header;
+- bits of CRC check;
+- bits of bit allocation;
+- the maximum number of bits in:
+  - scalefactor select information;
+  - scalefactors.
+
+Other parts of the signal are not protected.
+
+Single channel signals always use one Reed-Solomon codeword per frame. Stereo and dual channel signals at low bit rates use one and at high bit rates two Reed-Solomon codewords per frame (see Tables 5, 6 and 7).
+
+If there are two codewords, they are interleaved byte-by-byte according to the following scheme: The first transmitted byte is the first byte of codeword one, the second transmitted byte is the first byte of codeword two, the third transmitted byte is the second byte of codeword one, and so on. This means that the information itself is not interleaved.
+
+$$\begin{aligned} \text{Redundancy of code} \quad r_{\text{code}} &= \frac{4}{N} 100 (\%) \\ \text{Redundancy per frame} \quad r_{\text{frame}} &= 4 \frac{\text{codewords per frame}}{\text{byte per frame}} 100 (\%) \end{aligned}$$
+
+TABLE 5/J.52
+
+#### **Code parameters for a sampling frequency of 48 kHz (unequal error-control mode – mode 1 – for Layer II only)**
+
+| Bit rate<br>(kbit/s) | Bytes per<br>frame | Single channel      |              |                   |                    | Stereo or dual channel |              |                   |                    |
+|----------------------|--------------------|---------------------|--------------|-------------------|--------------------|------------------------|--------------|-------------------|--------------------|
+|                      |                    | No. of<br>codewords | K<br>(bytes) | $r_{code}$<br>(%) | $r_{frame}$<br>(%) | No. of<br>codewords    | K<br>(bytes) | $r_{code}$<br>(%) | $r_{frame}$<br>(%) |
+| 32                   | 96                 | 1                   | 28           | 12.5              | 4.2                | –                      | –            | –                 | –                  |
+| 48                   | 144                | 1                   | 28           | 12.5              | 2.8                | –                      | –            | –                 | –                  |
+| 56                   | 168                | 1                   | 83           | 4.6               | 2.4                | –                      | –            | –                 | –                  |
+| 64                   | 192                | 1                   | 83           | 4.6               | 2.1                | 1                      | 51           | 7.3               | 2.1                |
+| 80                   | 240                | 1                   | 83           | 4.6               | 1.7                | –                      | –            | –                 | –                  |
+| 96                   | 288                | 1                   | 83           | 4.6               | 1.4                | 1                      | 51           | 7.3               | 1.4                |
+| 112                  | 336                | 1                   | 83           | 4.6               | 1.2                | 2                      | 81           | 4.7               | 2.4                |
+| 128                  | 384                | 1                   | 83           | 4.6               | 1.0                | 2                      | 81           | 4.7               | 2.1                |
+| 160                  | 480                | 1                   | 83           | 4.6               | 0.8                | 2                      | 81           | 4.7               | 1.7                |
+| 192                  | 576                | 1                   | 83           | 4.6               | 0.7                | 2                      | 81           | 4.7               | 1.4                |
+| 224                  | 672                | –                   | –            | –                 | –                  | 2                      | 81           | 4.7               | 1.2                |
+| 256                  | 768                | –                   | –            | –                 | –                  | 2                      | 81           | 4.7               | 1.0                |
+| 320                  | 960                | –                   | –            | –                 | –                  | 2                      | 81           | 4.7               | 0.8                |
+| 384                  | 1152               | –                   | –            | –                 | –                  | 2                      | 81           | 4.7               | 0.7                |
+
+TABLE 6/J.52
+
+**Code parameters for a sampling frequency of 44.1 kHz  
+(unequal error-control mode – mode 1 – for Layer II only)**
+
+| Bit rate<br>(kbit/s) | Bytes per<br>frame | Single channel      |              |                   |                    | Stereo or dual channel |              |                   |                    |
+|----------------------|--------------------|---------------------|--------------|-------------------|--------------------|------------------------|--------------|-------------------|--------------------|
+|                      |                    | No. of<br>codewords | K<br>(bytes) | $r_{code}$<br>(%) | $r_{frame}$<br>(%) | No. of<br>codewords    | K<br>(bytes) | $r_{code}$<br>(%) | $r_{frame}$<br>(%) |
+| 32                   | 104.5              | 1                   | 28           | 12.5              | 3.8                | –                      | –            | –                 | –                  |
+| 48                   | 156.7              | 1                   | 28           | 12.5              | 2.6                | –                      | –            | –                 | –                  |
+| 56                   | 182.9              | 1                   | 83           | 4.6               | 2.2                | –                      | –            | –                 | –                  |
+| 64                   | 209.0              | 1                   | 83           | 4.6               | 1.9                | 1                      | 51           | 7.3               | 1.9                |
+| 80                   | 261.2              | 1                   | 83           | 4.6               | 1.5                | –                      | –            | –                 | –                  |
+| 96                   | 313.5              | 1                   | 91           | 4.2               | 1.3                | 1                      | 51           | 7.3               | 1.3                |
+| 112                  | 365.7              | 1                   | 91           | 4.2               | 1.1                | 2                      | 81           | 4.7               | 2.2                |
+| 128                  | 418.0              | 1                   | 91           | 4.2               | 1.0                | 2                      | 81           | 4.7               | 1.9                |
+| 160                  | 522.4              | 1                   | 91           | 4.2               | 0.8                | 2                      | 81           | 4.7               | 1.5                |
+| 192                  | 626.9              | 1                   | 91           | 4.2               | 0.6                | 2                      | 89           | 4.3               | 1.3                |
+| 224                  | 731.4              | –                   | –            | –                 | –                  | 2                      | 89           | 4.3               | 1.1                |
+| 256                  | 835.9              | –                   | –            | –                 | –                  | 2                      | 89           | 4.3               | 1.0                |
+| 320                  | 1044.9             | –                   | –            | –                 | –                  | 2                      | 89           | 4.3               | 0.8                |
+| 384                  | 1253.9             | –                   | –            | –                 | –                  | 2                      | 89           | 4.3               | 0.6                |
+
+TABLE 7/J.52
+
+**Code parameters for a sampling frequency of 32 kHz  
+(unequal error-control mode – mode 1 – for Layer II only)**
+
+| Bit rate<br>(kbit/s) | Bytes per<br>frame | Single channel      |              |                   |                    | Stereo or dual channel |              |                   |                    |
+|----------------------|--------------------|---------------------|--------------|-------------------|--------------------|------------------------|--------------|-------------------|--------------------|
+|                      |                    | No. of<br>codewords | K<br>(bytes) | $r_{code}$<br>(%) | $r_{frame}$<br>(%) | No. of<br>codewords    | K<br>(bytes) | $r_{code}$<br>(%) | $r_{frame}$<br>(%) |
+| 32                   | 144                | 1                   | 39           | 9.3               | 2.8                | –                      | –            | –                 | –                  |
+| 48                   | 216                | 1                   | 39           | 9.3               | 1.9                | –                      | –            | –                 | –                  |
+| 56                   | 252                | 1                   | 83           | 4.6               | 1.6                | –                      | –            | –                 | –                  |
+| 64                   | 288                | 1                   | 83           | 4.6               | 1.4                | 1                      | 74           | 5.1               | 1.4                |
+| 80                   | 360                | 1                   | 83           | 4.6               | 1.1                | –                      | –            | –                 | –                  |
+| 96                   | 432                | 1                   | 91           | 4.2               | 0.9                | 1                      | 74           | 5.1               | 0.9                |
+| 112                  | 504                | 1                   | 91           | 4.2               | 0.8                | 2                      | 81           | 4.7               | 1.6                |
+| 128                  | 576                | 1                   | 91           | 4.2               | 0.7                | 2                      | 81           | 4.7               | 1.4                |
+| 160                  | 720                | 1                   | 91           | 4.2               | 0.6                | 2                      | 81           | 4.7               | 1.1                |
+| 192                  | 864                | 1                   | 91           | 4.2               | 0.5                | 2                      | 89           | 4.3               | 0.9                |
+| 224                  | 1008               | –                   | –            | –                 | –                  | 2                      | 89           | 4.3               | 0.8                |
+| 256                  | 1152               | –                   | –            | –                 | –                  | 2                      | 89           | 4.3               | 0.7                |
+| 320                  | 1440               | –                   | –            | –                 | –                  | 2                      | 89           | 4.3               | 0.6                |
+| 384                  | 1728               | –                   | –            | –                 | –                  | 2                      | 89           | 4.3               | 0.5                |
+
+### 4.2 Equal error correction (only Layers II and III)
+
+The RS code defined above is used for protecting a complete frame. The more powerful error control of mode 3 is achieved by using more and shorter codewords per frame. The  $L$  codewords per frame are interleaved, in order to increase the error correction capability in case of burst errors. By this simple coding scheme only one encoder implementation, one decoder implementation and a flexible interleaver is required for all applications considered in this subclause. See Figure 7 for examples.
+
+![Diagram illustrating the coding scheme before interleaving for Mode 2 and Mode 3. At the top, a box represents a frame, with arrows indicating 1152 samples and 336 bytes (48 kHz). Below, Mode 2 is shown with two blocks of 168 codewords and one block of 2x4 codewords, totaling 2 (172, 168) codewords. Mode 3 is shown with eight blocks of 42 codewords and one block of 8x4 codewords, totaling 8 (46, 42) codewords. A small code T0902290-94/d07 is at the bottom right.](d734a6ea1b381280f043fcf70391b6db_img.jpg)
+
+The diagram illustrates the coding scheme before interleaving. At the top, a long horizontal rectangle represents a frame. Below it, two arrows indicate the frame duration: '1152 samples' and '336 bytes (48 kHz)'. Below this, two modes are shown. Mode 2 consists of three blocks: two blocks of 168 codewords and one block of  $2 \times 4$  codewords. An arrow below indicates a total of '2 (172, 168) codewords'. Mode 3 consists of nine blocks: eight blocks of 42 codewords and one block of  $8 \times 4$  codewords. An arrow below indicates a total of '8 (46, 42) codewords'. A small code 'T0902290-94/d07' is at the bottom right.
+
+Diagram illustrating the coding scheme before interleaving for Mode 2 and Mode 3. At the top, a box represents a frame, with arrows indicating 1152 samples and 336 bytes (48 kHz). Below, Mode 2 is shown with two blocks of 168 codewords and one block of 2x4 codewords, totaling 2 (172, 168) codewords. Mode 3 is shown with eight blocks of 42 codewords and one block of 8x4 codewords, totaling 8 (46, 42) codewords. A small code T0902290-94/d07 is at the bottom right.
+
+FIGURE 7/J.52  
+Examples for the coding scheme before interleaving
+
+For the sampling frequencies 48 kHz, 44.1 kHz and 32 kHz and for different bit rates, the code length  $N$  and the number  $L$  of codewords per frame are given in Tables 8, 9 and 10.
+
+In many cases two different code lengths  $N$  and  $N - 1$  are necessary in each frame. The number of codewords of length  $N$  is denoted by  $L_N$  and the number of codewords of length  $N - 1$  is denoted by  $L_{N-1}$ , where  $L = L_N + L_{N-1}$ . The redundancy is:
+
+$$r = \frac{4L}{\text{Number of bytes per frame}}$$
+
+For Layer III, the RS code is calculated based on the length of the ISO-frame taking into account the padding bit. If the padding bit is set, the following modifications occur:
+
+|                     |                     |                           |           |                   |
+|---------------------|---------------------|---------------------------|-----------|-------------------|
+| for $L_{N-1} > 0$ : | $L_N = L_N + 1$     | $L_{N-1} = L_{N-1} - 1$ , |           |                   |
+| or                  | for $L_{N-1} = 0$ : | $N = N + 1$               | $L_N = 1$ | $L_{N-1} = L - 1$ |
+
+For details of the performance, see Appendix I.
+
+TABLE 8/J.52
+
+#### **Code parameters for a sampling frequency of 48 kHz**
+
+| Bit rate (kbit/s) | Bytes per frame | N   | No. of codewords |                |                  | r (%) | N      | No. of codewords |                |                  | r (%) |
+|-------------------|-----------------|-----|------------------|----------------|------------------|-------|--------|------------------|----------------|------------------|-------|
+|                   |                 |     | L                | L <sub>N</sub> | L <sub>N-1</sub> |       |        | L                | L <sub>N</sub> | L <sub>N-1</sub> |       |
+| 32                | 96              | 100 | 1                | 1              | 0                | 4.17  | 52     | 2                | 2              | 0                | 8.33  |
+| 40                | 120             | 124 | 1                | 1              | 0                | 3.33  | 44     | 3                | 3              | 0                | 10.00 |
+| 48                | 144             | 148 | 1                | 1              | 0                | 2.78  | 52     | 3                | 3              | 0                | 8.33  |
+| 56                | 168             | 172 | 1                | 1              | 0                | 2.38  | 46     | 4                | 4              | 0                | 9.52  |
+| 64                | 192             | 196 | 1                | 1              | 0                | 2.08  | 43     | 5                | 2              | 3                | 10.42 |
+| 80                | 240             | 244 | 1                | 1              | 0                | 1.67  | 44     | 6                | 6              | 0                | 10.00 |
+| 96                | 288             | 148 | 2                | 2              | 0                | 2.78  | 46     | 7                | 1              | 6                | 9.72  |
+| 112               | 336             | 172 | 2                | 2              | 0                | 2.38  | 46     | 8                | 8              | 0                | 9.52  |
+| 128               | 384             | 196 | 2                | 2              | 0                | 2.08  | 47     | 9                | 6              | 3                | 9.38  |
+| 160               | 480             | 164 | 3                | 3              | 0                | 2.50  | 44     | 12               | 12             | 0                | 10.00 |
+| 192               | 576             | 196 | 3                | 3              | 0                | 2.08  | 46     | 14               | 2              | 12               | 9.72  |
+| 224               | 672             | 172 | 4                | 4              | 0                | 2.38  | 44     | 17               | 9              | 8                | 10.12 |
+| 256               | 768             | 158 | 5                | 3              | 2                | 2.60  | 45     | 19               | 8              | 11               | 9.09  |
+| 320               | 960             | 164 | 6                | 6              | 0                | 2.50  | 44     | 24               | 24             | 0                | 10.00 |
+| 384               | 1152            | 169 | 7                | 4              | 3                | 2.43  | 44     | 29               | 21             | 8                | 10.07 |
+| Mode 2            |                 |     |                  |                |                  |       | Mode 3 |                  |                |                  |       |
+
+TABLE 9/J.52
+
+#### **Code parameters for a sampling frequency of 44.1 kHz**
+
+| Bit rate (kbit/s) | Bytes per frame | N   | No. of codewords |                |                  | r (%) | N      | No. of codewords |                |                  | r (%) |
+|-------------------|-----------------|-----|------------------|----------------|------------------|-------|--------|------------------|----------------|------------------|-------|
+|                   |                 |     | L                | L <sub>N</sub> | L <sub>N-1</sub> |       |        | L                | L <sub>N</sub> | L <sub>N-1</sub> |       |
+| 32                | 104.4           | 108 | 1                | 1              | 0                | 3.83  | 56     | 2                | 2              | 0                | 7.66  |
+| 40                | 130.6           | 134 | 1                | 1              | 0                | 3.06  | 48     | 3                | 1              | 2                | 9.19  |
+| 48                | 156.7           | 160 | 1                | 1              | 0                | 2.55  | 43     | 4                | 4              | 0                | 10.21 |
+| 56                | 182.8           | 186 | 1                | 1              | 0                | 2.19  | 50     | 4                | 2              | 2                | 8.75  |
+| 64                | 208.9           | 212 | 1                | 1              | 0                | 1.91  | 46     | 5                | 3              | 2                | 9.57  |
+| 80                | 261.2           | 135 | 2                | 1              | 1                | 3.06  | 48     | 6                | 3              | 3                | 9.19  |
+| 96                | 313.4           | 161 | 2                | 1              | 1                | 2.55  | 44     | 8                | 1              | 7                | 10.21 |
+| 112               | 365.7           | 187 | 2                | 1              | 1                | 2.19  | 45     | 9                | 5              | 4                | 9.84  |
+| 128               | 417.9           | 213 | 2                | 1              | 1                | 1.91  | 46     | 10               | 7              | 3                | 9.57  |
+| 160               | 522.4           | 178 | 3                | 1              | 0                | 2.30  | 45     | 13               | 2              | 11               | 9.95  |
+| 192               | 626.9           | 161 | 4                | 2              | 2                | 2.55  | 46     | 15               | 11             | 4                | 9.57  |
+| 224               | 731.4           | 187 | 4                | 3              | 1                | 2.19  | 45     | 18               | 11             | 7                | 9.84  |
+| 256               | 835.9           | 171 | 5                | 5              | 0                | 2.39  | 44     | 21               | 16             | 5                | 10.05 |
+| 320               | 1044.8          | 178 | 6                | 6              | 0                | 2.30  | 45     | 26               | 4              | 22               | 9.95  |
+| 384               | 1253.8          | 161 | 8                | 5              | 3                | 2.55  | 45     | 31               | 13             | 18               | 9.89  |
+| Mode 2            |                 |     |                  |                |                  |       | Mode 3 |                  |                |                  |       |
+
+TABLE 10/J.52
+
+#### **Code parameters for a sampling frequency of 32 kHz**
+
+| Bit rate (kbit/s) | Bytes per frame | N   | No. of codewords |                |                  | r (%) | N      | No. of codewords |                |                  | r (%) |
+|-------------------|-----------------|-----|------------------|----------------|------------------|-------|--------|------------------|----------------|------------------|-------|
+|                   |                 |     | L                | L <sub>N</sub> | L <sub>N-1</sub> |       |        | L                | L <sub>N</sub> | L <sub>N-1</sub> |       |
+| 32                | 144             | 148 | 1                | 1              | 0                | 2.78  | 52     | 3                | 3              | 0                | 8.33  |
+| 40                | 180             | 184 | 1                | 1              | 0                | 2.22  | 49     | 4                | 4              | 0                | 8.89  |
+| 48                | 216             | 220 | 1                | 1              | 0                | 1.85  | 48     | 5                | 1              | 4                | 9.26  |
+| 56                | 252             | 130 | 2                | 2              | 0                | 3.17  | 46     | 6                | 6              | 0                | 9.52  |
+| 64                | 288             | 148 | 2                | 2              | 0                | 2.78  | 46     | 7                | 1              | 6                | 9.72  |
+| 80                | 360             | 184 | 2                | 2              | 0                | 2.22  | 44     | 9                | 9              | 0                | 10.00 |
+| 96                | 432             | 148 | 3                | 3              | 0                | 2.78  | 44     | 11               | 3              | 8                | 10.19 |
+| 112               | 504             | 172 | 3                | 3              | 0                | 2.38  | 46     | 12               | 12             | 0                | 9.52  |
+| 128               | 576             | 196 | 3                | 3              | 0                | 2.08  | 46     | 14               | 2              | 12               | 9.72  |
+| 160               | 720             | 184 | 4                | 4              | 0                | 2.22  | 44     | 18               | 18             | 0                | 10.00 |
+| 192               | 864             | 177 | 5                | 4              | 1                | 2.31  | 46     | 21               | 3              | 18               | 9.72  |
+| 224               | 1008            | 172 | 6                | 6              | 0                | 2.38  | 45     | 25               | 8              | 17               | 9.92  |
+| 256               | 1152            | 169 | 7                | 4              | 3                | 2.43  | 44     | 29               | 21             | 8                | 10.07 |
+| 320               | 1440            | 164 | 9                | 9              | 0                | 2.50  | 44     | 36               | 36             | 0                | 10.00 |
+| 384               | 1728            | 162 | 11               | 1              | 10               | 2.55  | 45     | 43               | 8              | 35               | 9.95  |
+| Mode 2            |                 |     |                  |                |                  |       | Mode 3 |                  |                |                  |       |
+
+#### **4.2.1 Computation of RS code for Layer II, by using the ancillary data field method**
+
+In this case some bit slots need to be reserved within the ISO frames capacity according to 3.1.2.1. See Figure 8.
+
+R<sub>h</sub> is the integer number of bytes to be stripped off for H.221 purposes and R<sub>rs</sub> is the integer number of bytes to be reserved for RS computation according to Tables 5, 6, 7, 8, 9 and 10. If H.221 framing is not used, R<sub>h</sub> = 0.
+
+![Diagram of an audio frame showing reserved slots for J.52 and FEC. The frame is a horizontal rectangle divided into three parts: a large left section, a middle section labeled R_h, and a right section labeled R_rs. A double-headed arrow below the frame indicates the total length L in bytes. The text 'T0903390-96/d08' is visible in the bottom right corner of the diagram area.](2734e7f9be3e1dc046f14be2e6c9a085_img.jpg)
+
+Diagram of an audio frame showing reserved slots for J.52 and FEC. The frame is a horizontal rectangle divided into three parts: a large left section, a middle section labeled R\_h, and a right section labeled R\_rs. A double-headed arrow below the frame indicates the total length L in bytes. The text 'T0903390-96/d08' is visible in the bottom right corner of the diagram area.
+
+FIGURE 8/J.52  
+**Audio frame with reserved slots for J.52 and FEC**
+
+RS code is computed according to the following procedure:
+
+- R<sub>h</sub> and R<sub>rs</sub> fields have to be set to zero;
+- Redundancy code is computed according to clause 4 for the words defined in Tables 5, 6, 7, 8, 9 and 10 on the whole frames including L bytes as defined in Table 2. L is the Length of the ISO-frame according to Table 2.
+
+Due to the differences between audio and H.221 frames' lengths, the padding bit is set from time to time according to the description made in clause 3.1.2.1.
+
+In case of setting the padding bit in the frame, in order to keep the parameters of the RS FEC equal to the parameters of frames not using the padding bit, the  $(R_{rs} + R_h) - 1$  slot (1 slot = 1 byte for Layer II and 4 bytes for Layer I) is set to zero at the end of the frame and the FEC on the whole frame (length = L bytes according to Table 2) is computed.
+
+In this case the extra slot belonging to the audio information is also protected.
+
+#### 4.2.2 Interleaving
+
+Block interleaving is proposed, where the first transmitted byte is the first byte of the first codeword, the second transmitted byte is the first byte of the second codeword, etc. The interleaving scheme is shown in Figure 9.
+
+Interleaving is accomplished in a way that the  $(i + k \cdot L)^{th}$  byte of each frame is the  $(k + 1)^{th}$  unaltered information byte of the  $i^{th}$  codeword with the following conventions:
+
+- i:  $i^{th}$  codeword ( $i = 1, 2, \dots, L$ ).
+- k:  $k^{th}$  bit of the codeword ( $k = 0, 1, \dots, N - 5$ ).
+- L: Number of codewords.
+- N: Length of the codeword.
+
+The encoding of each frame starts with encoding of the  $L_N$  codewords of length N byte.
+
+The effect of this block interleaving scheme and the systematic encoding is that the order and the values of the transmitted information bytes are not affected by the interleaving process and the encoding process, respectively. The additional  $4 L$  redundant bytes, derived in the RS-encoder, are transmitted at the end of each frame.
+
+Examples for this interleaving scheme are given in Figure 9.
+
+![Diagram illustrating the interleaving scheme for two different codeword configurations. The top part shows a frame length of 10 bytes, divided into 5 information bytes (1, 1, 1, 1, 1) and 5 redundancy bytes (2, 2, 2, 2, 2). The bottom part shows two examples: 1, 2: (9, 5) codewords, resulting in 4 information bytes (1, 1, 1, 1) and 8 redundancy bytes (2, 3, 2, 3, 2, 3, 2, 3); and 1: (8, 4) codewords and 2, 3: (7, 3) codewords, resulting in 4 information bytes (1, 1, 1, 1) and 8 redundancy bytes (2, 3, 2, 3, 2, 3, 2, 3).](f1fbb1287d999c7034742de35bdab836_img.jpg)
+
+Frame length 10 byte
+
+|   |   |   |   |   |   |   |   |   |   |
+|---|---|---|---|---|---|---|---|---|---|
+| 1 | 2 | 1 | 2 | 1 | 2 | 1 | 2 | 1 | 2 |
+|---|---|---|---|---|---|---|---|---|---|
+
+Information                      Redundancy
+
+1, 2: (9, 5) codewords
+
+|   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
+|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
+| 1 | 2 | 3 | 1 | 2 | 3 | 1 | 2 | 3 | 1 | 1 | 2 | 3 | 2 | 3 | 2 | 3 | 2 | 3 | 1 |
+|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
+
+Information                      Redundancy
+
+1: (8, 4) codewords  
+2, 3: (7, 3) codewords
+
+T0902300-94/d09
+
+Diagram illustrating the interleaving scheme for two different codeword configurations. The top part shows a frame length of 10 bytes, divided into 5 information bytes (1, 1, 1, 1, 1) and 5 redundancy bytes (2, 2, 2, 2, 2). The bottom part shows two examples: 1, 2: (9, 5) codewords, resulting in 4 information bytes (1, 1, 1, 1) and 8 redundancy bytes (2, 3, 2, 3, 2, 3, 2, 3); and 1: (8, 4) codewords and 2, 3: (7, 3) codewords, resulting in 4 information bytes (1, 1, 1, 1) and 8 redundancy bytes (2, 3, 2, 3, 2, 3, 2, 3).
+
+FIGURE 9/J.52  
+**Interleaving scheme**
+
+### 4.3 Position of redundancy
+
+In all cases, redundancy for error correction is inserted just before the header and corresponds to the following frame. Using the dynamic bit rate switching method, the length of the redundancy, located before the corresponding ISO-frame may vary from frame to frame. Only two different lengths are possible. To establish a proper synchronization both possible locations of the ISO syncword have to be tested. The decision is then made according to which length is proper for the following frame.
+
+## 5 Transmission of data
+
+The ancillary data field is defined by International Standard ISO/IEC 11172-3 to be the part of the frame, which is neither header nor audio data. For layers I and II the data field is at the end of the ISO frame, while for layer III the position is determined by pointers in the ISO-frame Side Information part. The International Standard does **not** define any structure or recommended use of the ancillary data field, but mutually incompatible application specific or proprietary formats exists.
+
+This Recommendation defines the structure for the ancillary data field. The use of this structure is optional. The decoder can detect whether this structure is in use by checking the pattern of the identification bit at the end of the ancillary data field (for further details see 5.2).
+
+The data format defined here is intended both for use with or without H.221 framing and/or FEC. The format supports a byte oriented transparent data channel, transmission of scalefactor CRCs, and other data.
+
+### 5.1 Types of data
+
+#### 5.1.1 Byte oriented transparent channel
+
+The transparent data channel allows for a byte oriented transfer of 8 bit characters, MSB first. The data bytes are put in reverse order in the bit stream, i.e. the last data byte in a frame corresponds to the first byte on the data interface. Applications should be tolerant to data loss.
+
+#### 5.1.2 Scalefactor CRC
+
+For detection of errors within the three MSB's of the scalefactors, CRC check words can optionally be inserted in the J.52 Layer I or Layer II frame. The CRC check words cover the scalefactors of the following subbands:
+
+- scfcrc0: subbands 0 ... 3 (subband group 0);
+- scfcrc1: subbands 4 ... 7 (subband group 1);
+- scfcrc2: subbands 8 ... 15 (subband group 2);
+- scfcrc3: subbands 16 and above (subband group 3).
+
+As the maximum number of subbands that can be allocated depends on the layer, sampling frequency and the bit rate per channel, the subband groups 2 and 3 can in some cases not have an allocation. Consequently, for those subband groups no scalefactor CRCs are contained in the bit stream:
+
+Layer I:
+
+for all combinations of sampling frequency and bit rate: 4 scfcrcs;
+
+Layer II:
+
+sblimit = 8: 2 scfcrcs (fs = 44.1 and 48 kHz, bit rate 32 and 48 kbit/s per channel);
+
+sblimit = 12: 3 scfcrcs (fs = 32 kHz, bit rate 32 and 48 kbit/s per channel);
+
+sblimit = 27 or 29 4 scfcrcs (fs = 32, 44.1 and 48 kHz, bit rate 56 kbit/s per channel or higher and free format).
+
+The error detection method used is “CRC-8”, whose generator polynomial is:
+
+$$G_2(x) = x^8 + x^4 + x^3 + x^2 + 1$$
+
+The bits included in the CRC-check are the three MSBs of all scalefactors of the corresponding subband group, in the order of their occurrence in the bit stream.
+
+The initial state of the scalefactor crc-register is binary “0000 0000”, i.e. all zeroes (note that the initial state for the crc-register defined by ISO/MPEG is binary “1111 1111 1111 1111” or hex \$FF FF. The ISO/MPEG CRC protects the bit allocation and scalefactor select information).
+
+The method for the calculation of the CRC is the same as for the ISO CRC, and can be found in ISO/IEC 11172-3.
+
+The scfcrcs are put in reverse order in the bit stream to keep the position of scfcrc0 and scfcrc1 independent from the sampling frequency and bit rate.
+
+The scfcrcs apply to the scalefactors in the following ISO frame. See Table 11.
+
+TABLE 11/J.52
+
+| Number of scfcrcs | Order in bit stream                |
+|-------------------|------------------------------------|
+| 2                 | scfcrc1, scfcrc0                   |
+| 3                 | scfcrc2, scfcrc1, scfcrc0          |
+| 4                 | scfcrc3, scfcrc2, scfcrc1, scfcrc0 |
+
+#### 5.1.3 Presentation time stamp
+
+Transmission of Presentation Time Stamps (PTSs) in each audio frame is possible by using a 5 byte data block in the ancillary data field. The 33 least significant bits represent the PTS, and the seven most significant bits are set to zero. The MSB is transmitted first. The PTS has a resolution of 90 kHz, and represents the time of the first sample in the following audio frame. For further details see 2.4.3.3 and 2.4.4.3 of ISO/IEC 11172-1.
+
+The transmission of PTS is optional on a frame-to-frame basis. The PTS can be recalculated by the decoder to other time code formats.
+
+### 5.2 J.52 data format
+
+The data format is self-identifying to allow easy coexistence with other pre-existing ancillary data formats, such as e.g. the PAD formats defined by Eureka 147 DAB or ADR. See Figure 10.
+
+If equal Error Protection is in use, the data channel is protected together with the rest of the ISO frame (or shortened frame in case H.221 framing is being used).
+
+| Available for audio data | Extension data | Extension header | $D_{L-1} \dots$ | Data | $\dots D_0$ | Data header   | X |
+|--------------------------|----------------|------------------|-----------------|------|-------------|---------------|---|
+| 1 byte (optional)        |                |                  | L bytes         |      |             | 1 ... 2 bytes |   |
+
+For Layer I and II, X denotes the header of the next ISO frame, or, in case FEC is used, the beginning of the FEC redundancy field. For Layer III, X denotes the beginning of the main data of the next ISO frame.  $D_0$  is the first byte and  $D_{L-1}$  the last byte received by the data interface.
+
+FIGURE 10/J.52
+
+### J.52 ancillary data format
+
+The data header is defined as follows for all layers as shown in Figure 11.
+
+![](69b7bd65e85cdef6fdd7fb0a8194257c_img.jpg)
+
+|                                          |    |    |    |    |    |   |   |                   |    |    |    |    |    |     |    |
+|------------------------------------------|----|----|----|----|----|---|---|-------------------|----|----|----|----|----|-----|----|
+| 15                                       | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7                 | 6  | 5  | 4  | 3  | 2  | 1   | 0  |
+| L                                        |    |    |    |    |    |   |   | L5                | L4 | L3 | L2 | L1 | L0 | ext | ID |
+| Optional (exists if L5...L0 = "11 1111") |    |    |    |    |    |   |   | Length indication |    |    |    |    |    |     |    |
+
+ID Identification, a serial bit channel. In subsequent frames, the pattern "00 0001" is repeated.
+
+ext extension, indicating whether more data than the transparent data channel is contained in the bit stream. Equals "0" if no extension data is present, "1" if extension data is present.
+
+L5 ... L0 Length indication, MSB first (number of data bytes). If L5 ... L0 = "11 1111", then there is an additional length byte (MSB first) which can indicate a length from 0 ... 255.
+
+If the "ext" bit in the data header equals "1", an extension header with the format shown in Figure 12 precedes the transparent data bytes.
+
+FIGURE 11/J.52
+
+### **J.52 Data header**
+
+![](55136bc716146672fc680fa05989f1d2_img.jpg)
+
+|  |    |     |     |     |     |     |    |    |
+|--|----|-----|-----|-----|-----|-----|----|----|
+|  | 7  | 6   | 5   | 4   | 3   | 2   | 1  | 0  |
+|  | Pr | Fu5 | Fu4 | Fu3 | Fu2 | Fu1 | PT | SC |
+
+SC To indicate whether Scalefactor CRCs are contained in the bit stream. Equals "0" if no Scalefactor CRCs are present, "1" if Scalefactor CRCs are present.
+
+PT To indicate whether presentation time stamp data are contained in the bit stream. Equals "0" if no PTS data are present, "1" if PTS data are present.
+
+Fu1 ... Fu5 Bits reserved for future use, not defined yet. Zero at present.
+
+Pr Bit for private use.
+
+FIGURE 12/J.52
+
+### **J.52 Data extension header**
+
+The extension data field has the format shown in Figure 13.
+
+![](db395493033edacd83e212049fd55715_img.jpg)
+
+|                         |                          |                  |
+|-------------------------|--------------------------|------------------|
+| Presentation Time Stamp | Scalefactor CRCs         | extension header |
+| 5 bytes (optional)      | 2 ... 4 bytes (optional) |                  |
+
+FIGURE 13/J.52
+
+### **J.52 Extension data**
+
+# Annex A
+
+## Digital transmission of medium-quality sound-programme signals using a 64 kbit/s channel (or a part thereof)
+
+(This annex forms an integral part of this Recommendation)
+
+### A.1 Introduction
+
+The International Standard ISO/IEC 13818-3 contains an extension of ISO/IEC 11172-3 to lower sampling frequencies. This extension provides an improved audio quality at the lowest bit rates, e.g. below 64 kbit/s per channel, at sampling frequencies which are half the sampling frequencies of ISO/IEC 11172-3 (16, 22.05 and 24 kHz).
+
+Although encoding to this part of ISO/IEC 13818-3 is not yet (end 1995) recommended by ITU-R Study Group 10, it is recognized that there is a demand from the market to transmit such signals over the transmission channels addressed in this Recommendation, and that this only requires minor modifications to this Recommendation. These adaptations are given in this annex. The implementation of the lower sample frequencies as such is not mandatory, but, when decided, must conform to this specification.
+
+### A.2 Possible bit rates
+
+See Table A.1.
+
+TABLE A.1/J.52
+
+| Bit rate index | Bit rate specified for $f_s = 16, 22.05, 24$ kHz (kbit/s) |                     |
+|----------------|-----------------------------------------------------------|---------------------|
+|                | Layer I                                                   | Layer II, Layer III |
+| "0000"         | free                                                      | free                |
+| "0001"         | 32                                                        | 8                   |
+| "0010"         | 48                                                        | 16                  |
+| "0011"         | 56                                                        | 24                  |
+| "0100"         | 64                                                        | 32                  |
+| "0101"         | 80                                                        | 40                  |
+| "0110"         | 96                                                        | 48                  |
+| "0111"         | 112                                                       | 56                  |
+| "1000"         | 128                                                       | 64                  |
+| "1001"         | 144                                                       | 80                  |
+| "1010"         | 160                                                       | 96                  |
+| "1011"         | 176                                                       | 112                 |
+| "1100"         | 192                                                       | 128                 |
+| "1101"         | 224                                                       | 144                 |
+| "1110"         | 256                                                       | 160                 |
+| "1111"         | forbidden                                                 | forbidden           |
+
+### A.3 Framelength
+
+For Layers I and II the framelength and padding sequence for the lower sampling frequencies (16, 22.05, 24 kHz) are to be calculated as in ISO/IEC 11172-3:
+
+$$\text{Layer I: framelength} = 12 \frac{\text{Bit rate}}{\text{Sampling frequency}} \text{ slots} \quad (\text{one slot equals 4 bytes})$$
+
+$$\text{Layer II: framelength} = 144 \frac{\text{Bit rate}}{\text{Sampling frequency}} \text{ slots} \quad (\text{one slot equals one byte})$$
+
+For Layer III, the framelength is to be calculated by:
+
+$$\text{Layer III: framelength} = 144 \frac{\text{Bit rate}}{2 (\text{Sampling frequency})} \text{ slots} \quad (\text{one slot equals one byte})$$
+
+### A.4 Realization of bit rates which are not explicitly listed in the bit rate table of the ISO/IEC 13818-3 Standard
+
+Adaptation of the explicitly listed bit rates accordingly to ISO/IEC 13818-3 Layer II to the available channel bit rate is done by using the ancillary data field method, as with the higher sampling frequencies. L and S are the length in bytes of a long frame and a short frame respectively, both without padding slot. See Table A.2.
+
+TABLE A.2/J.52
+
+Adaption of the explicit listed bit rates according to ISO/IEC 11172-3 to the desired bit rate (examples for Layer II)
+
+| Channels | Mode        | Useful data rate | Sampling frequency |      |           |     |        |     |
+|----------|-------------|------------------|--------------------|------|-----------|-----|--------|-----|
+|          |             |                  | 16 kHz             |      | 22,05 kHz |     | 24 kHz |     |
+|          |             |                  | L                  | S    | L         | S   | L      | S   |
+| 1        | in-band     | 62 400           | 576                | 561  | 417       | 407 | 384    | 374 |
+| 2        | in-band     | 124 800          | 1152               | 1123 | 835       | 815 | 768    | 748 |
+| 2        | in-band 56k | 108 800          | 1008               | 979  | 731       | 710 | 672    | 652 |
+
+Adaptation of the explicitly listed bit rates according to ISO/IEC 13818-3 Layer III to the available channel bit rate is done by using the dynamic bit rate switching method, as with the higher sampling frequencies. The tables for the sampling frequencies 32, 44.1 and 48 kHz in this Recommendation can also be used for the corresponding half sampling frequencies.
+
+### A.5 Error control
+
+For the lower sampling frequencies, Mode 1 (unequal error control) is currently not defined. Modes 2 and 3 (equal error control) are only defined for Layers II and III. The method is the same as for the higher sampling frequencies. Tables A.3, A.4 and A.5 apply for Layer II.
+
+TABLE A.3/J.52
+
+#### **Code parameters for a sampling frequency of 16 kHz (for Layer II)**
+
+| Bit rate<br>(kbit/s) | Bytes<br>per frame | N   | No. of codewords |                |                  | r (%) | N  | No. of codewords |                |                  | r (%) |
+|----------------------|--------------------|-----|------------------|----------------|------------------|-------|----|------------------|----------------|------------------|-------|
+|                      |                    |     | L                | L <sub>N</sub> | L <sub>N-1</sub> |       |    | L                | L <sub>N</sub> | L <sub>N-1</sub> |       |
+| 32                   | 288                | 148 | 2                | 2              | 0                | 2.78  | 46 | 7                | 1              | 6                | 9.72  |
+| 40                   | 360                | 184 | 2                | 2              | 0                | 2.22  | 44 | 9                | 9              | 0                | 10.00 |
+| 48                   | 432                | 148 | 3                | 3              | 0                | 2.78  | 48 | 10               | 2              | 8                | 9.26  |
+| 56                   | 504                | 172 | 3                | 3              | 0                | 2.38  | 46 | 12               | 12             | 0                | 9.52  |
+| 64                   | 576                | 148 | 4                | 4              | 0                | 2.78  | 46 | 14               | 2              | 12               | 9.72  |
+| 80                   | 720                | 148 | 5                | 5              | 0                | 2.78  | 44 | 18               | 18             | 0                | 10.00 |
+| 96                   | 864                | 148 | 6                | 6              | 0                | 2.78  | 46 | 21               | 3              | 18               | 9.72  |
+| 112                  | 1008               | 148 | 7                | 7              | 0                | 2.78  | 45 | 25               | 8              | 17               | 9.92  |
+| 128                  | 1152               | 148 | 8                | 8              | 0                | 2.78  | 46 | 28               |                | 28               | 9.72  |
+
+TABLE A.4/J.52
+
+#### **Code parameters for a sampling frequency of 22.05 kHz (for Layer II)**
+
+| Bit rate<br>(kbit/s) | Bytes<br>per frame | N   | No. of codewords |                |                  | r (%) | N  | No. of codewords |                |                  | r (%) |
+|----------------------|--------------------|-----|------------------|----------------|------------------|-------|----|------------------|----------------|------------------|-------|
+|                      |                    |     | L                | L <sub>N</sub> | L <sub>N-1</sub> |       |    | L                | L <sub>N</sub> | L <sub>N-1</sub> |       |
+| 32                   | 208                | 212 | 1                | 1              | 0                | 1.92  | 46 | 5                | 3              | 2                | 9.62  |
+| 40                   | 261                | 135 | 2                | 1              | 1                | 3.07  | 48 | 6                | 3              | 3                | 9.20  |
+| 48                   | 313                | 161 | 2                | 1              | 1                | 2.56  | 49 | 7                | 5              | 2                | 8.95  |
+| 56                   | 365                | 126 | 3                | 2              | 1                | 3.29  | 45 | 9                | 5              | 4                | 9.86  |
+| 64                   | 417                | 143 | 3                | 3              | 0                | 2.88  | 46 | 10               | 7              | 3                | 9.59  |
+| 80                   | 522                | 178 | 3                | 3              | 0                | 2.30  | 45 | 13               | 2              | 11               | 9.96  |
+| 96                   | 626                | 161 | 4                | 2              | 2                | 2.56  | 46 | 15               | 11             | 4                | 9.58  |
+| 112                  | 731                | 151 | 5                | 1              | 4                | 2.74  | 45 | 18               | 11             | 7                | 9.85  |
+| 128                  | 835                | 144 | 6                | 1              | 5                | 2.87  | 46 | 20               | 15             | 5                | 9.58  |
+
+TABLE A.5/J.52
+
+#### **Code parameters for a sampling frequency of 24 kHz (for Layer II)**
+
+| Bit rate<br>(kbit/s) | Bytes<br>per frame | N   | No. of codewords |                |                  | r (%) | N  | No. of codewords |                |                  | r (%) |
+|----------------------|--------------------|-----|------------------|----------------|------------------|-------|----|------------------|----------------|------------------|-------|
+|                      |                    |     | L                | L <sub>N</sub> | L <sub>N-1</sub> |       |    | L                | L <sub>N</sub> | L <sub>N-1</sub> |       |
+| 32                   | 192                | 196 | 1                | 1              | 0                | 2.08  | 52 | 4                | 4              | 0                | 8.33  |
+| 40                   | 240                | 124 | 2                | 2              | 0                | 3.33  | 44 | 6                | 6              | 0                | 10.00 |
+| 48                   | 288                | 148 | 2                | 2              | 0                | 2.78  | 46 | 7                | 1              | 6                | 9.72  |
+| 56                   | 336                | 172 | 2                | 2              | 0                | 2.38  | 46 | 8                | 8              | 0                | 9.52  |
+| 64                   | 384                | 196 | 2                | 2              | 0                | 2.08  | 47 | 9                | 6              | 3                | 9.38  |
+| 80                   | 480                | 164 | 3                | 3              | 0                | 2.50  | 44 | 12               | 12             | 0                | 10.00 |
+| 96                   | 576                | 148 | 4                | 4              | 0                | 2.78  | 46 | 14               | 2              | 12               | 9.72  |
+| 112                  | 672                | 139 | 5                | 2              | 3                | 2.98  | 46 | 16               | 16             | 0                | 9.52  |
+| 128                  | 768                | 158 | 5                | 3              | 2                | 2.60  | 45 | 19               | 8              | 11               | 9.90  |
+
+For Layer III, Tables 8, 9 and 10 for the sampling frequencies 32, 44.1 and 48 kHz in this Recommendation shall also be used for the corresponding half sampling frequencies.
+
+### A.6 Transmission of data
+
+The transmission of data is the same as for the higher sampling frequencies, except for the number of scalefactor CRCs (only Layers I and II). In the case of the lower sampling frequencies, there are 4 scalefactor CRCs, for all combinations of sampling frequency and bit rate.
+
+# Appendix I
+
+## Performance of the forward error correction
+
+(This appendix does not form an integral part of this Recommendation)
+
+Within each codeword, up to two ( $t < 2$ ) arbitrarily distributed byte errors can be corrected. The burst error correction capability  $b$  within each frame depends on the number  $L$  of codewords and the amount  $t$  of error correction:
+
+$$b \leq [(Lt - 1) 8 + 1] \text{ bits} \quad \text{for } t > 0$$
+
+In Figure I.1, the bit-error probability  $P_b$  after decoding is shown as a function of the number  $t$  of corrected symbol errors, the code length  $N$ , and the bit-error probability BER of the transmission channel, where statistically independent bit errors are assumed. For burst errors with the same BER within a frame, the performance is much better than shown in Figure I.1.
+
+The probability  $P_f$  of a falsely decoded word is shown in Figure I.2. The probability  $P_F$  of a falsely decoded frame (containing  $L$  codewords) is given by:
+
+$$P_F = 1 - (1 - P_f)^L$$
+
+It must be mentioned that even for  $t = 2$ , a high amount of uncorrectable error patterns can be detected by the RS-decoder. The reliability of error detection can further be increased by reducing  $t$ .
+
+![Log-log plot of Bit-error probability P_b vs BER for N = 44, 64, ..., 224 and t = 1, 2.](183007754364096b2d89f42200cf870f_img.jpg)
+
+This log-log plot shows the Bit-error probability  $P_b$  on the y-axis (ranging from  $10^{-14}$  to  $10^{-3}$ ) against the Bit Error Rate (BER) on the x-axis (ranging from  $10^{-8}$  to  $10^{-3}$ ). The plot contains multiple curves for different values of  $N$  (44, 64, ..., 224) and  $t$  (1, 2). The curves for  $t=1$  are higher than those for  $t=2$ . For each  $t$ , the curves are labeled with  $N=224$  and  $44$ . The curves show a linear increase on the log-log scale, indicating a power-law relationship between  $P_b$  and BER.
+
+Log-log plot of Bit-error probability P\_b vs BER for N = 44, 64, ..., 224 and t = 1, 2.
+
+T0902330-94/d10
+
+FIGURE I.1/J.52  
+**Bit-error probability  $P_b$  after decoding  $N = 44, 64, \dots, 224$**
+
+![Log-log plot of Falsely decoded word probability P_f vs BER for N = 44, 124, 224 and t = 0, 1, 2.](b9d879f357d5f15fac9ea8585b87d0a2_img.jpg)
+
+This log-log plot shows the Falsely decoded word probability  $P_f$  on the y-axis (ranging from  $10^{-11}$  to  $10^{-0}$ ) against the Bit Error Rate (BER) on the x-axis (ranging from  $10^{-8}$  to  $10^{-3}$ ). The plot contains multiple curves for different values of  $N$  (44, 124, 224) and  $t$  (0, 1, 2). The curves for  $t=0$  are the highest, followed by  $t=1$  and then  $t=2$ . For each  $t$ , the curves are labeled with  $N=224$ , 124, and 44. The curves show a linear increase on the log-log scale, indicating a power-law relationship between  $P_f$  and BER.
+
+Log-log plot of Falsely decoded word probability P\_f vs BER for N = 44, 124, 224 and t = 0, 1, 2.
+
+T0902340-94/d11
+
+FIGURE I.2/J.52  
+**Probability  $P_f$  of a falsely decoded codeword**
+
+# ITU-T RECOMMENDATIONS SERIES
+
+- Series A Organization of the work of the ITU-T
+- Series B Means of expression
+- Series C General telecommunication statistics
+- Series D General tariff principles
+- Series E Telephone network and ISDN
+- Series F Non-telephone telecommunication services
+- Series G Transmission systems and media
+- Series H Transmission of non-telephone signals
+- Series I Integrated services digital network
+- Series J Transmission of sound-programme and television signals**
+- Series K Protection against interference
+- Series L Construction, installation and protection of cables and other elements of outside plant
+- Series M 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
+- Series Q Switching and signalling
+- Series R Telegraph transmission
+- Series S Telegraph services terminal equipment
+- Series T Terminal equipments and protocols for telematic services
+- Series U Telegraph switching
+- Series V Data communication over the telephone network
+- Series X Data networks and open system communication
+- Series Z Programming languages
\ No newline at end of file
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+
+
+![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**
+
+**J.55**
+
+**(ex CMTT.718)**
+
+**(06/90)**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**TELEVISION AND SOUND TRANSMISSION**
+
+---
+
+**DIGITAL TRANSMISSION OF HIGH-QUALITY  
+SOUND-PROGRAMME SIGNALS ON  
+DISTRIBUTION CIRCUITS USING 480 kbit/s  
+(496 kbit/s) PER AUDIO CHANNEL**
+
+**ITU-T Recommendation J.55**
+
+(Formerly Recommendation ITU-R CMTT.718)
+
+---
+
+# 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 J.55 (formerly Recommendation ITU-R CMTT.718) was elaborated by the former ITU-R Study Group CMTT. See Note 1 below.
+
+# --- 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 (ITU-R).
+
+Conforming to a joint decision by the World Telecommunication Standardization Conference (Helsinki, March 1993) and the Radiocommunication Assembly (Geneva, November 1993), the ITU-R Study Group CMTT was transferred to ITU-T as Study Group 9, except for the satellite news gathering (SNG) study area which was transferred to ITU-R Study Group 4.
+
+2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+# **DIGITAL TRANSMISSION OF HIGH-QUALITY SOUND-PROGRAMME SIGNALS ON DISTRIBUTION CIRCUITS USING 480 kbit/s (496 kbit/s) PER AUDIO CHANNEL**
+
+(1990)
+
+The CCIR,
+
+## CONSIDERING
+
+- a) that the distribution of high-quality sound-programme signals from the studio to transmitters and users does not require further audio downstream processing;
+- b) that in general more than one high-quality sound-programme signal has to be conveyed over distribution circuits as in the case of DBS;
+- c) that a sampling frequency of 32 kHz is recommended for the digital transmission of high-quality sound-programme signals (Recommendation 606);
+- d) that some digital broadcasting applications may require system performances that go beyond those offered by equipment complying with CCIR Recommendation 660;
+- e) that the high-quality sound-programme signals should interface the ISDN at the H1 level as specified in CCITT Recommendation I.412,
+
+## UNANIMOUSLY RECOMMENDS
+
+- 1. that for distribution applications where a sampling frequency of 32 kHz is used and where a dynamic range corresponding to more than 14 bits is required the coding method described in § 1 of Annex I should be used on links providing a BER of less than  $10^{-5}$ ;
+- 2. that for transmission at H12 level, two stereophonic programmes or four monophonic programmes should be multiplexed according to the format described in § 2 of Annex I;
+- 3. that for cases where a higher ancillary data capacity is required and dedicated 2048 kbit/s links are available, the coding method and multiplexing format described in Annexe II should be used.
+
+*Note* – Exchange of international digital sound-programme signals on networks with other hierarchical rates (1544 kbit/s in North America) shall be made using Recommendation 660.
+
+---
+
+<sup>1)</sup> Formerly Recommendation ITU-R CMTT.718.
+
+# DIGITAL TRANSMISSION OF HIGH-QUALITY SOUND-PROGRAMME SIGNALS ON DISTRIBUTION CIRCUITS USING 480 kbit/s AUDIO CHANNEL
+
+## **1. Coding characteristics**
+
+### **1.1** *Sampling frequency*
+
+The sampling frequency shall be 32 kHz. The sampling frequency tolerance shall be  $\pm 5 \times 10^{-5}$ , as specified in CCITT Recommendations G.732 and G.733 for primary PCM multiplex equipment. This sampling frequency is consistent with that indicated in CCIR Recommendation 606.
+
+### **1.2** *Coding method*
+
+16/14-bit floating point companding with a 2 ms coding block length (i.e. 64 consecutive samples per block) and a 3-bit scale factor (transmitted by signalling in parity).
+
+The 16-bit samples of the sound signal are represented in a 2's complement format. The first bit of each word is the MSB (sign bit, 0 ~ +), and the last the LSB. Using a floating point system, the 16-bit samples are converted into 14-bit code words for transmission.
+
+A 3-bit scale factor applying to a block of 64 samples indicates how many of the bits (0 . . . 7) following the sign bit ( $y_1$ ) in all sampled words have the same value as the sign bit (Fig. 1a)). The redundancy indicated by the scale factor does not need to be transmitted. Instead, the samples and their relevant information must be shifted towards the sign bits (floating-point system). This allows the 15th and 16th bits of the source code words to be transmitted in the case of low signal amplitudes. The bits marked Z1 to Z5 have not yet been assigned (Fig. 1b)).
+
+At the receiving end the scale factor is used to shift the bits of the samples back to their original value. This yields 16-bit samples and limits the effects of unrecognizable bit errors to the amplitude range indicated by the scale factor.
+
+### **1.3** *Sample error-protection*
+
+After having applied the floating-point technique for reducing the bits per sample from 16 to 14, a parity bit is calculated on the seven most significant bits of each sample, such that the number of "1"s in the group of the seven protected bits and the parity bit is odd. Thus, the best protection against clicks due to bit errors is guaranteed provided concealment in the form of the arithmetic mean value of the samples adjacent to the faulty sample is performed at the receiving end. If the concealment is done after the 14/16 bit reconversion, errors in least significant bits can also be concealed in an optimum way.
+
+### **1.4** *Ancillary data*
+
+A data capacity of 4 kbit/s per channel is transmitted by signalling in parity.
+
+### **1.5** *Signalling in parity [Chambers, 1985]*
+
+Signalling in parity is achieved by transmitting the parity bits of an odd number of successive samples without inversion or after inversion, depending on the bit to be signalled. Inversion has to be done, if the bit to be transmitted is 1. The signalling technique used for the scale factor, its related parity bit, and the ancillary data is based on majority-decision logic at the receiver: for each channel, it processes twelve groups of five consecutive samples (three for the scale factor, one for its parity bit and eight for the ancillary data) to recognize simultaneously the odd or even parity of the sample and the data signalled in parity (see Fig. 2). A similar process is used to recognize the synchronization of the 2 ms frames through one group of four consecutive samples.
+
+### **1.6** *Total bit rate*
+
+With the parameters mentioned above the total bit rate required for one monophonic channel is 480 kbit/s [ $32 \text{ kHz} \times (14 + 1) \text{ bit}$ ].
+
+Scale factor
+
+|       |       |       |
+|-------|-------|-------|
+| 0     | 0     | 0     |
+| 0     | 0     | 1     |
+| 0     | 1     | 0     |
+| 0     | 1     | 1     |
+| 1     | 0     | 0     |
+| 1     | 0     | 1     |
+| 1     | 1     | 0     |
+| 1     | 1     | 1     |
+| 1     | 1     | 1     |
+| 1     | 1     | 0     |
+| 1     | 0     | 1     |
+| 1     | 0     | 0     |
+| 0     | 1     | 1     |
+| 0     | 1     | 0     |
+| 0     | 0     | 1     |
+| 0     | 0     | 0     |
+| $S_2$ | $S_1$ | $S_0$ |
+
+![Coding scheme diagram showing a grid of bits Y1-Y16 and Z1-Z5. A shaded region indicates the relevant sound signal code word range. The grid contains 0s and 1s in a staircase pattern, and Xs in the top and bottom right corners.](e394c2b5c61344f6a12397f430086072_img.jpg)
+
+*a) Coding scheme*
+
+Coding scheme diagram showing a grid of bits Y1-Y16 and Z1-Z5. A shaded region indicates the relevant sound signal code word range. The grid contains 0s and 1s in a staircase pattern, and Xs in the top and bottom right corners.
+
+a) Coding scheme
+
+![Transmission format diagram showing a grid mapping source bits Y1-Y16 and Z1-Z5 to transmission bits b0-b13. The grid shows which source bits are selected for each scale factor row.](53f1f7d17b3e7aae62169c41d2a88a77_img.jpg)
+
+*b) Transmission format*
+
+Transmission format diagram showing a grid mapping source bits Y1-Y16 and Z1-Z5 to transmission bits b0-b13. The grid shows which source bits are selected for each scale factor row.
+
+b) Transmission format
+
+FIGURE 1 — 16/14 bit floating-point method
+
+![Legend box with a dotted pattern representing the relevant sound signal code word range.](764bb8d7c93b090e205d908e1a8cade4_img.jpg)
+
+Legend box with a dotted pattern representing the relevant sound signal code word range.
+
+relevant sound signal code word range of the 16-bit source signal words
+
+![Legend box with 'X X' representing non-transmittable bits.](04519be9bd73b202914a1bb3da732edd_img.jpg)
+
+Legend box with 'X X' representing non-transmittable bits.
+
+non-transmittable bits of the 16-bit source signal words
+
+d01-sc
+
+![Diagram showing signalling in parity coding for one audio channel. It consists of three parts: a) Parity bits (P) for 64 samples, with bit positions 1, 5, 10, 15, 20, 25, 30, 50, 55, 60, 64 marked. b) Sync pattern (0101), scale factor (S0, S1, S2), parity bit, and ancillary data (Bit 1 to Bit 8). c) Modified parity bits. A 2 ms duration is indicated at the bottom.](547f726730e589392f239257a833ede3_img.jpg)
+
+Diagram showing signalling in parity coding for one audio channel. It consists of three parts: a) Parity bits (P) for 64 samples, with bit positions 1, 5, 10, 15, 20, 25, 30, 50, 55, 60, 64 marked. b) Sync pattern (0101), scale factor (S0, S1, S2), parity bit, and ancillary data (Bit 1 to Bit 8). c) Modified parity bits. A 2 ms duration is indicated at the bottom.
+
+FIGURE 2 – *Signalling in parity coding for one audio channel*
+
+- a) Parity bits (P denotes the parity bit associated to each individual audio sample).
+- b) Sync pattern, scale factor, parity bit for the scale factor and ancillary data bits. The parity bit for the scale factor should be even as shown in the example.
+- c) Modified parity bits.
+
+d02-sc
+
+## 2. Frame structure for transmission
+
+Within the ISDN, a usable bit rate of 1920 kbit/s for one multiplex frame is available according to CCITT Recommendation G.704.
+
+In order to ensure the compatibility between the signals transmitted at 480 kbit/s according to this Recommendation with those transmitted at 384 kbit/s according to CCITT Recommendation G.737, the bits of each audio channel should be allocated according to the present proposal depicted in Fig. 3. The bits of each audio channel should be transmitted as a group of 30 bits within a half-frame.
+
+Moreover, the bits of each sample are interleaved such that the most significant bit (MSB) is followed by the least significant bit (LSB), etc. (see Fig. 3). This arrangement of bits has proven to be a good protection against double errors, which otherwise cannot be recognized by a single parity bit and thus cannot be concealed.
+
+On this basis, channels using 480 kbit/s and 384 kbit/s can be combined according to Table I:
+
+TABLE I
+
+|     | Number of channels |            |
+|-----|--------------------|------------|
+|     | 480 kbit/s         | 384 kbit/s |
+| I   | 4                  | 0          |
+| II  | 3                  | 1          |
+| III | 2                  | 2          |
+| IV  | 1                  | 3          |
+| V   | 0                  | 5          |
+
+![Diagram showing five channel configurations (I-V) for audio transmission. At the top, two rows of bits are shown: the first row has bits b0 through b13, followed by parity bits P, then repeating b0 through b13 and P; the second row is an interleaved version with bits b13 down to b0, followed by P, MSB, LSB, and then repeating P, MSB, LSB. Below this, five channel diagrams (I-V) show how these bits are mapped. Channel I shows a 32-bit frame with bits 0-31, containing sub-channels D, C, B, A, and 16. Channel II shows a similar frame but with some bits marked as unusable (crossed out). Channels III, IV, and V show variations with different sub-channel combinations (a, b, c, d, e) and unusable bits.](fc46871d72c65d3381d9201646d23439_img.jpg)
+
+Diagram showing five channel configurations (I-V) for audio transmission. At the top, two rows of bits are shown: the first row has bits b0 through b13, followed by parity bits P, then repeating b0 through b13 and P; the second row is an interleaved version with bits b13 down to b0, followed by P, MSB, LSB, and then repeating P, MSB, LSB. Below this, five channel diagrams (I-V) show how these bits are mapped. Channel I shows a 32-bit frame with bits 0-31, containing sub-channels D, C, B, A, and 16. Channel II shows a similar frame but with some bits marked as unusable (crossed out). Channels III, IV, and V show variations with different sub-channel combinations (a, b, c, d, e) and unusable bits.
+
+FIGURE 3
+
+A, B, C, D: monophonic channel 480 kbit/s  
+ a, b, c, d, e: monophonic channel 384 kbit/s  
+ MSB: most significant bit  
+ LSB: least significant bit  
+
+Image: crossed out box symbol
+
+ : not usable for sound transmission
+
+d03-sc
+
+Two monophonic channels of the same coding scheme can be combined to form a stereophonic channel. In some realized systems for 384 kbit/s channels only the combinations a, b and c, d are possible to form stereophonic channels.
+
+## REFERENCES
+
+CHAMBERS, J. P. [1985] Signalling in parity: a brief history. British Broadcasting Corporation, BBC RD 1985/15.
+
+# DIGITAL TRANSMISSION OF HIGH-QUALITY SOUND-PROGRAMME SIGNAL ON DISTRIBUTION CIRCUITS USING 496 kbit/s PER AUDIO CHANNEL
+
+## 1. Coding characteristics
+
+### 1.1 Sampling frequency
+
+See Annex I.
+
+### 1.2 Coding method
+
+See Annex I.
+
+### 1.3 Sample error-protection
+
+See Annex I.
+
+### 1.4 Ancillary data
+
+12 kbit/s per channel are available for transmission of ancillary data.
+
+### 1.5 Signalling in parity [Chambers, 1985]
+
+Signalling in parity is achieved by transmitting the parity bits of an odd number of successive samples without inversion or after inversion, depending on the bit to be signalled. Inversion has to be done, if the bit to be transmitted is "1". The signalling technique used for the scale factor is based on majority-decision logic at the receiver: for each channel, it processes three groups of twenty-one consecutive samples to recognize simultaneously the odd or even parity of the sample and the data signalled in parity (see Fig. 4).
+
+![Diagram illustrating signalling in parity coding for one audio channel over a 2 ms time interval. The diagram is divided into three horizontal tracks: a) Parity bits (P), b) Scale factor bits (1 1 0), and c) Modified parity bits (P-bar). Track a) shows 64 samples, with parity bits P for each. Track b) shows 21 groups of 3 bits (1 1 0), with the first group labeled 1 2 3 4 5 6 7 8 9 and the last group labeled 17 18 19 20 21. Track c) shows the modified parity bits, which are inverted (P-bar) for some groups. The scale factor bits are also shown in track c) as S0 S1 S2.](740442c999390734911677f01af0316d_img.jpg)
+
+The diagram shows three horizontal tracks labeled a), b), and c) over a 2 ms time interval, divided into 64 sample slots. Track a) shows parity bits (P) for each sample. Track b) shows scale factor bits in groups of three (1 1 0), numbered 1 through 21. Track c) shows modified parity bits, which are inverted (P-bar) for some groups. The scale factor bits are also shown in track c) as S<sub>0</sub> S<sub>1</sub> S<sub>2</sub>.
+
+Diagram illustrating signalling in parity coding for one audio channel over a 2 ms time interval. The diagram is divided into three horizontal tracks: a) Parity bits (P), b) Scale factor bits (1 1 0), and c) Modified parity bits (P-bar). Track a) shows 64 samples, with parity bits P for each. Track b) shows 21 groups of 3 bits (1 1 0), with the first group labeled 1 2 3 4 5 6 7 8 9 and the last group labeled 17 18 19 20 21. Track c) shows the modified parity bits, which are inverted (P-bar) for some groups. The scale factor bits are also shown in track c) as S0 S1 S2.
+
+FIGURE 4 — Signalling in parity coding for one audio channel
+
+- a) Parity bits (P denotes the parity bit associated to each individual audio sample)
+- b) Scale factor bits
+- c) Modified parity bits
+
+d04-sc
+
+### 1.6 Synchronization
+
+4 kbit/s are used for synchronization of the floating point companding block.
+
+### 1.7 Total bit rate
+
+With the parameters mentioned above the total bit rate required for one monophonic channel is 496 kbit/s [32 kHz × (14 + 1) bits + 12 kbit/s + 4 kbit/s].
+
+## 2. Frame structure for transmission
+
+The frame structure for transmission is based on an interface operating at 1024 kbit/s.
+
+Two of the 496 kbit/s channels are combined with a frame alignment signal to form a multiplexed signal of 1024 kbit/s, which constitutes the bit rate of the interface. The structure of the frame is almost the same as that specified in CCITT Recommendation G.704 for the primary hierarchical level of 2048 kbit/s. It should be noted that the frame repetition rate is 4 kHz instead of 8 kHz. The frame format is shown in Fig. 5.
+
+![Diagram of the frame structure for the 1024 kbit/s signal. The top part shows a 26-bit word for each channel (Left and Right), consisting of a parity bit (P), 13 data bits (13-0), and a parity bit (P). Bit 0 is the most significant bit, Bit 13 is the least significant bit, and P is the parity bit. The bottom part shows the 256-bit frame structure, which is 8 bits (frame alignment signal) followed by 10 blocks of 30 bits each. The first 30-bit block is a 'Synchronization and data block' containing 8 bits (S_L, 1_L, 2_L, 3_L, S_R, 1_R, 2_R, 3_R) and 22 bits of data. The remaining 9 blocks are 30 bits of data each. The frame is divided into two 128-bit halves, labeled 'Left channel' and 'Right channel'.](b3baf3a29b67c7425d2562ddbc52f0cc_img.jpg)
+
+Diagram of the frame structure for the 1024 kbit/s signal. The top part shows a 26-bit word for each channel (Left and Right), consisting of a parity bit (P), 13 data bits (13-0), and a parity bit (P). Bit 0 is the most significant bit, Bit 13 is the least significant bit, and P is the parity bit. The bottom part shows the 256-bit frame structure, which is 8 bits (frame alignment signal) followed by 10 blocks of 30 bits each. The first 30-bit block is a 'Synchronization and data block' containing 8 bits (S\_L, 1\_L, 2\_L, 3\_L, S\_R, 1\_R, 2\_R, 3\_R) and 22 bits of data. The remaining 9 blocks are 30 bits of data each. The frame is divided into two 128-bit halves, labeled 'Left channel' and 'Right channel'.
+
+FIGURE 5 – Frame for the 1024 kbit/s signal with a length of 256 bits and a 4 kHz repetition rate
+
+$S_L, S_R$ : synchronization signal for floating point companding
+
+$\left. \begin{matrix} 1_L, 2_L, 3_L \\ 1_R, 2_R, 3_R \end{matrix} \right\}$  ancillary data signal
+
+d05-sc
+
+For each channel, the synchronization of the floating point companding block (64 samples carried in 8 frames) is achieved by means of an 8-bit synchronization word.
+
+Two synchronization words are defined:
+
+$$S_y = 00011011$$
+
+$$S_1 \dots S_8$$
+
+and the inverted form
+
+$$\bar{S}_y = 11100100$$
+
+$$\bar{S}_1 \dots \bar{S}_8$$
+
+For a stereophonic pair the synchronization word used is  $S_y$  for the left channel and  $\bar{S}_y$  for the right channel.
+
+For monophonic applications, the synchronization word used for each channel is alternatively  $S_y$  and  $\overline{S_y}$  (see Fig. 6).
+
+![Figure 6: Transmission of the synchronization words. It consists of two diagrams, (a) and (b), separated by a downward arrow labeled 'Transmission order'. Diagram (a) shows a 'Stereophonic pair' with two columns, S_L and S_R. S_L contains 8 samples (S1-S8) followed by another 8 samples (S1-S8) and then S1, S2. S_R contains 8 samples (S1-S8) followed by another 8 samples (S1-S8) and then S1, S2. Above the first column of S_L are labels 1_L, 2_L, 3_L. Above the first column of S_R are labels 1_R, 2_R, 3_R. Diagram (b) shows 'Two monophonic channels' with two columns, S_L and S_R. S_L contains 8 samples (S1-S8) followed by another 8 samples (S1-S8) and then S1, S2. S_R contains 8 samples (S1-S8) followed by another 8 samples (S1-S8) and then S1, S2. Above the first column of S_L are labels 1_L, 2_L, 3_L. Above the first column of S_R are labels 1_R, 2_R, 3_R. The transmission order is indicated by a downward arrow between the two diagrams.](f4fdd410cdb84df81274da55721e56fb_img.jpg)
+
+Figure 6: Transmission of the synchronization words. It consists of two diagrams, (a) and (b), separated by a downward arrow labeled 'Transmission order'. Diagram (a) shows a 'Stereophonic pair' with two columns, S\_L and S\_R. S\_L contains 8 samples (S1-S8) followed by another 8 samples (S1-S8) and then S1, S2. S\_R contains 8 samples (S1-S8) followed by another 8 samples (S1-S8) and then S1, S2. Above the first column of S\_L are labels 1\_L, 2\_L, 3\_L. Above the first column of S\_R are labels 1\_R, 2\_R, 3\_R. Diagram (b) shows 'Two monophonic channels' with two columns, S\_L and S\_R. S\_L contains 8 samples (S1-S8) followed by another 8 samples (S1-S8) and then S1, S2. S\_R contains 8 samples (S1-S8) followed by another 8 samples (S1-S8) and then S1, S2. Above the first column of S\_L are labels 1\_L, 2\_L, 3\_L. Above the first column of S\_R are labels 1\_R, 2\_R, 3\_R. The transmission order is indicated by a downward arrow between the two diagrams.
+
+a) Stereophonic pair
+
+b) Two monophonic channels
+
+*Note* — The relation between  $S_L$  and  $S_R$  should be as shown.
+
+*Note* — For monophonic application there is no need for a fixed relation between  $S_L$  and  $S_R$ .
+
+FIGURE 6 — Transmission of the synchronization words
+
+d06-sc
+
+By way of synchronous insertion into a 2048 kbit/s frame structure, it is not necessary to transmit the frame alignment signal (FA) which is contained in the frame structure shown in Fig. 5.
+
+Thus, for one channel the net bit rate for transmission is still 496 kbit/s.
+
+In cases where dedicated 2048 kbit/s links are available, up to four 496 kbit/s channels can be combined in one multiplex frame according to CCITT Recommendation G.704.
+
+In order to ensure compatibility between the signals transmitted at 496 kbit/s according to this Annex II with those transmitted at 384 kbit/s according to CCITT Recommendation G.737, the available transmission capacity should be allocated as shown in Fig. 7 [CCIR, 1982-86a].
+
+In Fig. 7 each block L I, R I, L II, R II comprises 60 bits corresponding to a capacity equivalent to 4 samples. Each block results from bit- and sample-interleaving over two consecutive Recommendation G.704 frames.
+
+![](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg)
+
+1) 
+
+|   |   |   |   |   |   |   |   |   |   |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |    |
+|---|---|---|---|---|---|---|---|---|---|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|
+| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 |
+|---|---|---|---|---|---|---|---|---|---|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|----|
+
+  
+ Frame according to Recommendation G.704
+
+2) 
+
+|   |      |  |  |  |  |  |  |     |  |  |  |  |  |  |  |      |  |  |  |  |  |  |  |     |  |  |  |  |  |  |  |
+|---|------|--|--|--|--|--|--|-----|--|--|--|--|--|--|--|------|--|--|--|--|--|--|--|-----|--|--|--|--|--|--|--|
+| 0 | R II |  |  |  |  |  |  | R I |  |  |  |  |  |  |  | L II |  |  |  |  |  |  |  | L I |  |  |  |  |  |  |  |
+|---|------|--|--|--|--|--|--|-----|--|--|--|--|--|--|--|------|--|--|--|--|--|--|--|-----|--|--|--|--|--|--|--|
+
+SD II
+SD I
+
+ Allocation of 2 stereophonic pairs
+
+3) 
+
+|   |   |  |  |   |  |  |   |   |     |  |  |  |  |  |    |   |  |  |   |  |  |    |     |  |  |  |  |  |  |
+|---|---|--|--|---|--|--|---|---|-----|--|--|--|--|--|----|---|--|--|---|--|--|----|-----|--|--|--|--|--|--|
+| 0 | a |  |  | b |  |  | 7 | ☒ | R I |  |  |  |  |  | 16 | a |  |  | b |  |  | 23 | L I |  |  |  |  |  |  |
+|---|---|--|--|---|--|--|---|---|-----|--|--|--|--|--|----|---|--|--|---|--|--|----|-----|--|--|--|--|--|--|
+
+SD I
+
+ Mixed allocation
+
+**FIGURE 7 — Allocation of available transmission capacity**
+
+L I:  $7.5 \times 64$  kbit/s = 480 kbit/s for left channel I  
+ R I: 480 kbit/s for right channel I  
+ L II: 480 kbit/s for left channel II  
+ R II: 480 kbit/s for right channel II
+
+SD I:  $0.5 \times 64$  kbit/s = 32 kbit/s, to be divided into  $2 \times 16$  kbit/s.
+
+In the frames containing the frame alignment word the data capacity is allocated to the left channel I, in the other frames to right channel I. In each case 4 kbit/s are used for synchronization of the floating point companding block and 12 kbit/s are used for the transmission of ancillary data
+
+SD II: as SD I but for channels L II and R II
+
+a, b: each  $2 \times 3 \times 64$  kbit/s = 384 kbit/s monophonic channel
+
+☒ : capacity not usable (32 kbit/s) in this combination
+
+*Note* — In line 3) above time slots 7 and 23 are available for telephone; the signalling channel (time slot 16) is not occupied by a sound channel.
+
+d07-sc
+
+## REFERENCES
+
+CHAMBERS, J. P. [1985] Signalling in parity: a brief history. British Broadcasting Corporation, BBC RD 1985/15.
+
+*CCIR Documents*
+
+[1982-86]: **a.** CMTT/214 (Germany (Federal Republic of)).
\ No newline at end of file
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.602**
+
+(06/2008)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Transport of Large Screen Digital Imagery
+
+---
+
+**Network service operator's requirements for  
+real-time transmission of exLSDI signals under  
+parallel processing functionality**
+
+Recommendation ITU-T J.602
+
+
+
+# **Recommendation ITU-T J.602**
+
+# **Network service operator's requirements for real-time transmission of exLSDI signals under parallel processing functionality**
+
+# **Summary**
+
+Recommendation ITU-T J.602 describes network operator's requirements with regard to a real-time transmission system applicable to signals in the extended LSDI hierarchy according to Recommendation ITU-T J.601.
+
+## **Source**
+
+Recommendation ITU-T J.602 was approved on 13 June 2008 by ITU-T Study Group 9 (2005-2008) under 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 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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    |
+| 2.1 Normative References .....                                                                                         | 1    |
+| 2.2 Informative References .....                                                                                       | 1    |
+| 3 Terms and definitions .....                                                                                          | 1    |
+| 4 Abbreviations.....                                                                                                   | 1    |
+| 5 Target applications.....                                                                                             | 2    |
+| 6 Requirements .....                                                                                                   | 2    |
+| 6.1 Performance.....                                                                                                   | 2    |
+| 6.2 Functionality.....                                                                                                 | 2    |
+| 6.3 Interoperability .....                                                                                             | 3    |
+| Appendix I – Example of functional components for Transmission System for signals in the extended LSDI hierarchy ..... | 4    |
+| I.1 Functional Components formulation .....                                                                            | 4    |
+| I.2 Encoder.....                                                                                                       | 4    |
+| I.3 Transmission system .....                                                                                          | 4    |
+| I.4 Decoder.....                                                                                                       | 4    |
+| Appendix II – Example of software encoder implementation .....                                                         | 5    |
+
+# **Introduction**
+
+The general information about an encoding scheme, a multiplexing scheme and a transport protocol for signals in the extended LSDI hierarchy is listed in Recommendation ITU-T J.601. On the other hand, several trials are currently conducted to evaluate a number of systems for the transmission of such signals, and an international standard which recommends a transmission system is required to maintain functionality and interoperability at a sufficient level. This Recommendation describes network operator's requirements with regard to a real-time transmission system applicable to signals in the extended LSDI hierarchy based on the technologies defined in Recommendation ITU-T J.601.
+
+## Recommendation ITU-T J.602
+
+# Network service operator's requirements for real-time transmission of exLSDI signals under parallel processing functionality
+
+# 1 Scope
+
+This Recommendation specifies network service operator's requirements for a real-time transmission system for signals in the extended LSDI hierarchy, including an encoder and a decoder. Appendix II describes, for information purposes, a method based on the use of parallel processing for encoding images in the extended LSDI hierarchy. The described parallel processing includes a spatially segmented method, a temporally interleaved method, a frequency sub-band division method and possible hybrid schemes of those methods.
+
+NOTE – The structure and content of this Recommendation have been organized for ease of use by those familiar with the original source material; as such, the usual style of ITU-T recommendations has not been applied.
+
+# 2 References
+
+## 2.1 Normative 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 J.601] Recommendation ITU-T J.601 (2005), *Transport of Large Screen Digital Imagery (LSDI) applications for its expanded hierarchy*.
+
+[ITU-R BT.1769] Recommendation ITU-R BT.1769 (2006), *Parameter values for an expanded hierarchy of LSDI image formats for production and international programme exchange*.
+
+[ITU-R BT.1121-1] Recommendation ITU-R BT.1121-1 (1995), *User requirements for the transmission through contribution and primary distribution networks of digital HDTV signals*.
+
+[ITU-R BS.1548-2] Recommendation ITU-R BS.1548-2 (2006), *User requirements for audio coding systems for digital broadcasting*.
+
+## 2.2 Informative References
+
+[ITU-T J.600] Recommendation ITU-T J.600 (2004), *Transport of Large Screen Digital Imagery (LSDI) applications that employ MPEG-2 encoded HDTV signals*.
+
+# 3 Terms and definitions
+
+This Recommendation defines no additional term.
+
+# 4 Abbreviations
+
+This Recommendation uses no new abbreviations.
+
+# 5 Target applications
+
+This Recommendation focuses on a transmission of signals in the extended LSDI hierarchy for contribution and primary distribution purposes.
+
+# 6 Requirements
+
+The network operator's requirements below apply, from the stand point of transmission service operators. The network operator's requirements focus on operator's aspects regarding network interoperability and operation functionality including service provisioning and monitoring in addition to the fundamental requirements to maintain the transmission service quality itself.
+
+## 6.1 Performance
+
+### 1) *Encoder processing time*
+
+The overall encoder process including image and audio buffering, video encoding, audio encoding and system multiplexing should be completed at a speed corresponding to real-time processing.
+
+### 2) *Coding efficiency*
+
+For video encoding and audio encoding, the coding bit rate should be selected to satisfy contribution and primary distribution quality. Those required quality level should be determined by further study. As the starting point of this study, [ITU-R BT.1121-1] and [ITU-R BS.1548-2] are appropriate references for video and audio, respectively. In the case that parallel processing is employed for video encoding, motion compensated prediction and rate control should be employed across image processing boundaries to improve coding efficiency. For video encoding, picture quality discontinuities should be negligible along boundaries among segmented images, if a parallel processing is adopted for spatially segmented images.
+
+### 3) *Encoding latency*
+
+For video encoding and audio encoding, the latency due to processing time for encoding a picture and corresponding audio should be uniform and independent of the image resolution in order to achieve a capability of a seamless switching between different hierarchies of the extended LSDI.
+
+### 4) *Video and audio synchronization*
+
+Video and audio streams should be synchronized within a sufficient accuracy. Especially, lip synchronization should be accomplished when audio and video streams are encoded simultaneously.
+
+### 5) *Error performance and recovery time*
+
+Error performance and recovery time should be determined by further study. As the starting point of this study, [ITU-R BT.1121-1] and [ITU-R BS.1548-2] are appropriate references for video and audio, respectively.
+
+## 6.2 Functionality
+
+To achieve a transmission functionality and a reliable service monitoring, the following requirements apply.
+
+### 1) *Multi-format support*
+
+A common processing platform may be utilized to support several image resolutions within the range of image system in the extended LSDI hierarchy, specified in [ITU-R BT.1769].
+
+### 2) *Notification of spatial dependency*
+
+The transmission process should be capable of notifying a spatial dependency in a full resolution picture if parallel processing is adopted for spatially segmented images.
+
+### 3) *Notification of resolution layer dependency*
+
+The transmission process should be capable of notifying a resolution layer dependency if a functionality of a spatial scalability is utilized in a video coding process.
+
+### 4) *Single bitstream support*
+
+For video signals, a single resolution layer should be transmitted by a single bitstream as long as applied video coding standard can support the corresponding image resolution, in order to maintain the monitoring precision when commercial measuring equipments fully compliant with a video coding standard are employed.
+
+## **6.3 Interoperability**
+
+### 1) *Bitstream conformance*
+
+The transmitted bitstream should comply with international video coding standards as those listed in [ITU-T J.601].
+
+# Appendix I
+
+## Example of functional components for Transmission System for signals in the extended LSDI hierarchy
+
+(This appendix does not form an integral part of this Recommendation)
+
+## I.1 Functional Components formulation
+
+To specify the scope of this Recommendation, functional components are formulated as shown in Figure I.1. Each function and implementation example is described. The interface boundary between a network service operator and a service user corresponds to A and D.
+
+![Figure I.1: Interface among transmission equipments. A horizontal timeline diagram showing the flow of video data through five functional components: Authoring, Encoder, Transmission, Decoder, and Display. The components are separated by vertical lines representing interfaces, labeled A, B, C, and D from left to right. Interface A is labeled '(Video In)', B is '(Transport Out)', C is '(Transport In)', and D is '(Video Out)'.](b8661c6c54f72ecc7ff6cb05e47b2891_img.jpg)
+
+The diagram illustrates a linear flow of video data through five functional components: Authoring, Encoder, Transmission, Decoder, and Display. A horizontal line with an arrow pointing to the right represents the data flow. Vertical lines mark the interfaces between these components, labeled A, B, C, and D from left to right. Below the labels, the interface types are specified: A (Video In), B (Transport Out), C (Transport In), and D (Video Out).
+
+Figure I.1: Interface among transmission equipments. A horizontal timeline diagram showing the flow of video data through five functional components: Authoring, Encoder, Transmission, Decoder, and Display. The components are separated by vertical lines representing interfaces, labeled A, B, C, and D from left to right. Interface A is labeled '(Video In)', B is '(Transport Out)', C is '(Transport In)', and D is '(Video Out)'.
+
+Figure I.1 – Interface among transmission equipments
+
+## I.2 Encoder
+
+The encoder compresses the input video signal in real time, and emits the processed data as a transport format. [ITU-T J.601] lists some coding schemes applicable to signals in the extended LSDI hierarchy.
+
+Some implementations employ a parallel processing due to the large amount of video data in the considered signals.
+
+## I.3 Transmission system
+
+[ITU-T J.601] lists some transmission mechanism applicable for the transmission of signals in the extended LSDI hierarchy, such as multiplexing or framing methods as well as transport methods.
+
+## I.4 Decoder
+
+The decoder decompresses the received data and outputs the video signal in real time. [ITU-T J.601] lists some coding schemes applicable to signals in the extended LSDI hierarchy.
+
+# Appendix II
+
+## Example of software encoder implementation
+
+(This appendix does not form an integral part of this Recommendation)
+
+The system architecture of software real-time encoder using distributed computing technology is addressed here. In Figure II.1, the assumed process configuration of coding node is along the MC+DCT coding framework just as in the case of MPEG coding standards. However, the reference architecture itself does not restrict the coding scheme. Since the process conducted by a coding node is provided by software module, shifting to another new coding scheme can be realized as well as enabling unsupported coding function within a specific coding scheme just by reloading the proper software module. In order to maintain a high coding efficiency, following framework is introduced.
+
+![Block diagram of the example encoder system showing two coding nodes (#1 and #2) processing video frames from a 4K Video File. Each node contains an Original Segmented frame, ME (Motion Estimation), Prediction image, subtraction and addition nodes, T (Transform), Q (Quantization), VLC (Variable Length Coding), Local decoder, and Stream buffer. A shared Frame memory is accessible among nodes. The output of the Stream buffers is sent to a Front end node via a Multi plexer.](d26959f4514c26ca19c3d6f00da85956_img.jpg)
+
+The diagram illustrates the architecture of a distributed video encoder system. A '4K Video File' is input to a 'Front end node'. The 'Front end node' sends 'Original Segmented frame' data to two 'Coding node' units, labeled #1 and #2. Each coding node contains the following components: an 'Original Segmented frame' input, an 'ME' (Motion Estimation) block, a 'Prediction image' block, a subtraction node (circle with a minus sign), a 'T' (Transform) block, a 'Q' (Quantization) block, a 'VLC' (Variable Length Coding) block, a 'Local decoder' block, and a 'Stream buffer' block. The 'ME' block takes the 'Original Segmented frame' and a 'Prediction image' as input and outputs a 'Prediction image'. The subtraction node takes the 'Original Segmented frame' and the 'Prediction image' as input and outputs a residual signal. The 'T' block takes the residual signal and outputs a transformed signal. The 'Q' block takes the transformed signal and outputs a quantized signal. The 'VLC' block takes the quantized signal and outputs a coded signal. The 'Local decoder' block takes the coded signal and outputs a decoded signal. The 'Stream buffer' block takes the coded signal and outputs a stream of data. A shared 'Frame memory' block is located between the two coding nodes, with a label 'Accessible among nodes' below it. The 'Frame memory' block is connected to the 'ME' and 'Prediction image' blocks in both coding nodes. The output of the 'Stream buffer' in each coding node is sent to a 'Multi plexer' block. The 'Multi plexer' block is connected to a 'Front end node' block.
+
+Block diagram of the example encoder system showing two coding nodes (#1 and #2) processing video frames from a 4K Video File. Each node contains an Original Segmented frame, ME (Motion Estimation), Prediction image, subtraction and addition nodes, T (Transform), Q (Quantization), VLC (Variable Length Coding), Local decoder, and Stream buffer. A shared Frame memory is accessible among nodes. The output of the Stream buffers is sent to a Front end node via a Multi plexer.
+
+Figure II.1 – Block diagram of the example encoder system
+
+- a) To maintain the high performance in motion compensated prediction, local decoded images stored in a coding node can be referred from the other coding nodes which handle adjacent image segment.
+- b) In order to suppress the picture quality difference among neighbouring image segments, the front end node conducts the bit assignment for every image segment prior to initializing encoder process for the current video frame. As the additional advantage introduced by applying this mechanism, the active bit allocation among segmented images can be realized, this may achieve a kind of statistical multiplexing gain.
+
+For the prototype encoder, preliminary experiments are conducted on the typical PC cluster equipped with 12 CPUs. In this experiment, the encoder software is based on MPEG-2. As the test sequence for 4K digital cinema (4096 × 2160, 24 Hz, progressive scan: DCI spec.), DCI StEM (Standard Evaluation Material) is utilized for the experiment. As a pre-process for MPEG-2 based encoding, input signals are converted into YUV format with 4:2:0 chroma sub-sampling.
+
+For simplifying a problem, 4K resolution image is divided into 8 segments whose size is 2048 pixels  $\times$  540 lines, and a coding node is applied for every segments. In order to evaluate the scalability of this scheme, the relation between the number of coding nodes operating simultaneously and the total system performance is observed. At the maximum case, 8 coding nodes are operated for handling 4K resolution. As the intermediate example, the case of 4 coding nodes is also evaluated. The relation between the number of coding nodes and the total processing time for a video frame is shown in Table II.1. From the result, performance degradation on the processing time for a video frame is limited, when the number of coding nodes operating simultaneously increases. This means the system performance increases almost linearly according to the number of coding nodes. In this experiment, the target frame rate is 24 Hz due to the input video format, but the architecture is applicable for other frame rate formats.
+
+**Table II.1 – Processing time for the number of coding nodes**
+
+| Number of coding nodes | Processing time for 1 frame [ms] |       |           |       |
+|------------------------|----------------------------------|-------|-----------|-------|
+|                        | I-picture                        |       | P-picture |       |
+|                        | Average                          | Max   | Average   | Max   |
+| 1                      | 25.61                            | 27.93 | 25.63     | 34.65 |
+| 4                      | 25.72                            | 28.74 | 26.01     | 36.24 |
+| 8                      | 25.15                            | 30.97 | 26.05     | 38.92 |
+
+Furthermore, in order to evaluate the significance of the interaction among coding nodes as mentioned above, coding performance is observed. The rate distortion curve is shown in Figure II.2. The result when encoding without the interaction is also shown in the Figure. In order to focus on the prediction gain, the rate control is centralized by the front end node in both cases. The PSNR was calculated as a temporally average value for Y component signals. From the result, the PSNR gain could be achieved by this scheme. This result illustrates the significance of the interaction among nodes in the sense of sharing the reference image for motion compensated prediction.
+
+![Line graph showing Averaged PSNR dB vs Coding Bit-rate Mbps for two cases: 'With interaction' (blue line) and 'No interaction' (magenta line). The x-axis ranges from 10 to 22 Mbps. The y-axis ranges from 31.5 to 35.0 dB. The 'With interaction' curve starts at approx (10.5, 32.3) and ends at approx (20.5, 34.9). The 'No interaction' curve starts at approx (11.0, 32.0) and ends at approx (21.5, 34.7).](252ea48d02dce93965b91746fb376f35_img.jpg)
+
+| Coding Bit-rate (Mbps) | Averaged PSNR dB (With interaction) | Averaged PSNR dB (No interaction) |
+|------------------------|-------------------------------------|-----------------------------------|
+| 11                     | 32.5                                | 32.0                              |
+| 12                     | 32.8                                | 32.4                              |
+| 14                     | 33.4                                | 33.0                              |
+| 16                     | 33.9                                | 33.5                              |
+| 18                     | 34.4                                | 34.0                              |
+| 20                     | 34.9                                | 34.4                              |
+
+Line graph showing Averaged PSNR dB vs Coding Bit-rate Mbps for two cases: 'With interaction' (blue line) and 'No interaction' (magenta line). The x-axis ranges from 10 to 22 Mbps. The y-axis ranges from 31.5 to 35.0 dB. The 'With interaction' curve starts at approx (10.5, 32.3) and ends at approx (20.5, 34.9). The 'No interaction' curve starts at approx (11.0, 32.0) and ends at approx (21.5, 34.7).
+
+**Figure II.2 – Averaged PSNR obtained by the encoder in this Appendix**
+
+
+
+###### SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                    |
+|-----------------|----------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                  |
+| Series B        | Available                                                                                          |
+| Series C        | Available                                                                                          |
+| 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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 W        | Available                                                                                          |
+| 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                               |
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.83**
+
+(12/2007)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Digital transmission of television signals
+
+---
+
+**Digital multi-programme systems for television,  
+sound and data services for cable distribution**
+
+Recommendation ITU-T J.83
+
+
+
+# **Recommendation ITU-T J.83**
+
+# **Digital multi-programme systems for television, sound and data services for cable distribution**
+
+# **Summary**
+
+Recommendation ITU-T J.83 covers the definition of the framing structure, channel coding and modulation for digital multi-programme signals for television, sound and data services distributed by cable networks.
+
+This Recommendation has four annexes (Annexes A, B, C and D) that provide the specifications for the four digital television cable systems submitted to the ITU-T. This reflects the fact that a number of digital cable television systems had been developed and provisionally implemented before this standardization effort was undertaken by ITU.
+
+This Recommendation recommends that those implementing new digital multi-programme services on existing and future cable networks should use one of the systems whose framing structure, channel coding and modulation are specified in Annexes A, B, C and D.
+
+## **Source**
+
+Recommendation ITU-T J.83 was approved on 14 December 2007 by ITU-T Study Group 9 (2005-2008) under 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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            | Terms and definitions .....                                 | 2    |
+| 4            | Symbols and abbreviations .....                             | 2    |
+| 4.1          | Symbols .....                                               | 2    |
+| 4.2          | Abbreviations .....                                         | 3    |
+| 5            | Digital multi-programme systems for cable distribution..... | 4    |
+| Annex A      | – Digital multi-programme System A .....                    | 6    |
+| A.1          | Introduction .....                                          | 6    |
+| A.2          | Specification .....                                         | 6    |
+| Annex B      | – Digital multi-programme System B.....                     | 7    |
+| B.1          | Introduction .....                                          | 7    |
+| B.2          | Cable system concept .....                                  | 7    |
+| B.3          | MPEG-2 transport layer .....                                | 8    |
+| B.4          | MPEG-2 transport framing.....                               | 8    |
+| B.5          | Forward error correction.....                               | 12   |
+| B.6          | Modulation and demodulation.....                            | 26   |
+| Annex C      | – Digital multi-programme System C.....                     | 28   |
+| C.1          | Introduction .....                                          | 28   |
+| C.2          | Cable system concept .....                                  | 28   |
+| C.3          | MPEG-2 transport layer .....                                | 29   |
+| C.4          | Framing structure.....                                      | 29   |
+| C.5          | Channel coding.....                                         | 30   |
+| C.6          | Modulation .....                                            | 32   |
+| Annex D      | – Digital multi-programme System D .....                    | 40   |
+| D.1          | Introduction .....                                          | 40   |
+| D.2          | Cable system concept .....                                  | 40   |
+| D.3          | MPEG-2 transport layer .....                                | 41   |
+| D.4          | Framing structure.....                                      | 41   |
+| D.5          | Channel coding.....                                         | 43   |
+| D.6          | Modulation .....                                            | 48   |
+| D.7          | 16-VSB cable receiver.....                                  | 49   |
+| D.8          | Other VSB modes.....                                        | 50   |
+| Bibliography | .....                                                       | 58   |
+
+# Introduction
+
+The development of new digital technologies is now reaching the point at which it is evident that they enable digital systems to offer significant advantages, in comparison with conventional analogue techniques, in terms of vision and sound quality, spectrum and power efficiency, service flexibility, multimedia convergence and potentially lower equipment costs. Moreover, the use of cable distribution for the delivery of video and audio signals to individual viewers and listeners is continually growing, and has already become the dominant form of distribution in many parts of the world. It is also evident that these potential benefits can best be achieved through the economies of scale resulting from the widespread use of digital systems designed to be easily implementable on existing infrastructure and which take advantage of the many possible synergies with related audiovisual systems.
+
+Administrations and private operators planning the introduction of digital cable television services are encouraged to consider the use of one of the systems described in Annexes A, B, C and D, and to seek opportunities for further convergence, rather than developing a different system based on the same technologies.
+
+The second edition (1997) of this Recommendation incorporated Amendment 1 (10/1996), which brought the following changes with respect to the first edition of the Recommendation:
+
+- a) Annex B includes a specification for 256-QAM;
+- b) In Annex B, two distinct operating modes of interleaving capability are specified, called *level 1* and *level 2*. Level 1 is specified for 64-QAM transmission only and this mode already existed in the first edition of Annex B. Level 2 encompasses 64-QAM and 256-QAM transmission, and for both modulation schemes is capable of supporting variable interleaving.
+- c) In the first edition of Annex D, 24 bits were identified which determined the VSB mode for the data in the frame and two such modes were defined: 16-VSB Cable and 8-VSB Terrestrial (trellis coded). With the second edition, three other VSB modes are defined, i.e., 2-VSB, 4-VSB and 8-VSB.
+
+The third edition (2007) of this Recommendation enhanced the modulation method by adding 128 QAM and 256 QAM in Annex A and 256 QAM in Annex C.
+
+# Digital multi-programme systems for television, sound and data services for cable distribution
+
+# 1 Scope
+
+The scope of this Recommendation is the definition of the framing structure, channel coding and modulation for digital multi-programme television, sound and data signals distributed by cable networks (e.g., CATV systems) possibly in frequency-division multiplex. A separate Recommendation defines the transmission characteristics for digital multi-programme signals distributed through SMATV networks.
+
+NOTE 1 – The system input is specified to be the MPEG-2 transport layer; this provides some ancillary data capacity in the forward channel, which can be used to accommodate the needs of interactive services (a description of the provision and characteristics of the return channel is outside the scope of this Recommendation).
+
+Being highly flexible, the MPEG-2 transport layer can be configured to deliver any desired mix of television, sound and data signals (with sound either related or unrelated to the video signal content, and at various possible levels of quality). The transport layer can even be totally devoted to the delivery of sound programming, although it may not necessarily be optimized for this application.
+
+The specific case of the delivery of a multiplex only containing sound signals may be addressed in a future Recommendation.
+
+This Recommendation is intended to ensure that the designers and operators of cable distribution (e.g., CATV) networks carrying multi-programme signals will have the information they need to be able to establish and maintain fully satisfactory networks. It also provides the information needed by the designers and manufacturers of equipment (including receivers) for digital multi-programme signals distributed by cable networks.
+
+NOTE 2 – The structure and content of this Recommendation have been organized for ease of use by those familiar with the original source material; as such, the usual style of ITU-T Recommendations has not been applied.
+
+# 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 published regularly. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [1] Recommendation ITU-R BO.1211 (1995), *Digital multi-programme emission systems for television, sound and data services for satellites operating in the 11/12 GHz frequency range*.
+- [2] Recommendation ITU-T H.222.0 (1995) | ISO/IEC 13818-1:1996, *Information technology – Generic coding of moving pictures and associated audio information: Systems*.
+- [3] European Telecommunications Standards Institute (ETSI) EN 300 429 V1.2.1 (1998-04), *Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for cable systems*.
+
+# 3 Terms and definitions
+
+No unconventional terms or definitions are used in this Recommendation.
+
+# 4 Symbols and abbreviations
+
+## 4.1 Symbols
+
+This Recommendation uses the following symbols:
+
+|             |                                                                              |
+|-------------|------------------------------------------------------------------------------|
+| $\alpha$    | Roll-off factor                                                              |
+| $A_k, B_k$  | Most Significant Bits at the output of the Byte to m-tuple converter         |
+| byte        | Eight bits                                                                   |
+| $f_0$       | Channel centre frequency                                                     |
+| $f_N$       | Nyquist frequency                                                            |
+| $g(x)$      | RS code generator polynomial                                                 |
+| $G_{(256)}$ | RS primitive field generator polynomial                                      |
+| $G_{(16)}$  | Randomizer generator polynomial                                              |
+| $I$         | Interleaving depth (bytes)                                                   |
+| $I, Q$      | In-phase, Quadrature phase components of the modulated signal                |
+| $j$         | Branch index                                                                 |
+| $k$         | Number of bytes mapped into $n$ symbols                                      |
+| $m$         | Power of $2^m$ -level QAM: 4,5,6 for 16-QAM, 32-QAM, 64-QAM, respectively    |
+| $M$         | Convolutional interleaver branch depth for $j = 1$ , $M = N/I$               |
+| ms          | millisecond                                                                  |
+| $n$         | Number of symbols mapped from $k$ bytes                                      |
+| $N$         | Error protected frame length (bytes)                                         |
+| $p(x)$      | RS field generator polynomial                                                |
+| $PN(x)$     | Pseudorandom sequence, identified by the number following the symbol         |
+| $q$         | Number of bits: 2,3,4 for 16-QAM, 32-QAM, 64-QAM, respectively               |
+| $R$         | Randomized sequence                                                          |
+| $r_m$       | In-band ripple (dB)                                                          |
+| $R_s$       | Symbol rate corresponding to bilateral Nyquist bandwidth of modulated signal |
+| $R_u$       | Useful bit rate after MPEG-2 transport multiplexer                           |
+| $R_{u'}$    | Bit rate after RS outer coder                                                |
+| $T$         | Number of bytes which can be corrected in RS error-protected packet          |
+| $T_s$       | Symbol period                                                                |
+
+## 4.2 Abbreviations
+
+This Recommendation uses the following abbreviations:
+
+|       |                                             |
+|-------|---------------------------------------------|
+| ATM   | Asynchronous Transfer Mode                  |
+| BB    | BaseBand                                    |
+| BER   | Bit Error Ratio                             |
+| bps   | Bits per second                             |
+| CATV  | Community Antenna Television                |
+| C/N   | Carrier to Noise ratio                      |
+| DTVC  | Digital Television by Cable                 |
+| FEC   | Forward Error Correction                    |
+| FIFO  | First In First Out                          |
+| HEC   | Header Error Control                        |
+| HEX   | Hexadecimal                                 |
+| IF    | Intermediate Frequency                      |
+| IRD   | Integrated Receiver Decoder                 |
+| LSB   | Least Significant Bit                       |
+| MMDS  | Multichannel Multipoint Distribution System |
+| MPEG  | Moving Picture Experts Group                |
+| MSB   | Most Significant Bit                        |
+| MUX   | Multiplex                                   |
+| P     | Parity                                      |
+| PDH   | Plesiochronous Digital Hierarchy            |
+| PN    | Pseudorandom Noise                          |
+| ppm   | Parts per million                           |
+| PRBS  | PseudoRandom Binary Sequence                |
+| QAM   | Quadrature Amplitude Modulation             |
+| QEF   | Quasi Error Free                            |
+| RF    | Radio Frequency                             |
+| RS    | Reed-Solomon                                |
+| SMATV | Satellite Master Antenna Television         |
+| SNR   | Signal-to-Noise Ratio                       |
+| sps   | Symbols per second                          |
+| Sync  | Synchronizing signal                        |
+| TBD   | To Be Determined                            |
+| TDM   | Time Division Multiplex                     |
+
+|        |                              |
+|--------|------------------------------|
+| TS     | Transport Stream             |
+| VLSI   | Very Large Scale Integration |
+| VSB    | Vestigial SideBand           |
+| XOR    | Exclusive OR                 |
+| 2-VSB  | 2 level VSB                  |
+| 4-VSB  | 4 level VSB                  |
+| 8-VSB  | 8 level VSB                  |
+| 16-VSB | 16 level VSB                 |
+
+# 5 Digital multi-programme systems for cable distribution
+
+It is recommended that those implementing new digital multi-programme services on existing and future cable networks should use one of the systems whose framing structure, channel coding and modulation are specified in Annexes A, B, C and D. The specifications are compared in Table 1, indicating common features.
+
+**Table 1 – Comparison of specifications in summary form indicating common features**
+
+| Item              |               | Annex B                                                                                                                                                                                                                                                                       | Annex A                                                                                                         | Annex C | Annex D                                                                                                                |
+|-------------------|---------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------|---------|------------------------------------------------------------------------------------------------------------------------|
+| Input signals     |               | Modified MPEG-2 transport stream. A parity checksum is substituted for the sync byte, supplying improved packet delineation functionality, and error detection capability independent of the FEC layer.<br>(See B.4.)                                                         | MPEG-2 transport Stream<br>(See Clause 5 in [3], C.3, D.3.)                                                     |         |                                                                                                                        |
+| Framing structure |               | An FEC frame consists of a 42- or 40-bit sync trailer following 60 or 88 RS blocks, with each block containing 128 symbols. An RS symbol consists of 7 bits. Thus, there is a total of 53 802 or 78 888 bits in an FEC frame for 64- or 256-QAM respectively.<br>(See B.5.3.) | The framing organization is based on the MPEG-2 transport packet structure.<br>(See Clause 6 in [3], C.4, D.4.) |         |                                                                                                                        |
+| Channel coding    | Randomization | The 3-word polynominal for the PRS:<br>$x^3 + x + \alpha^3$ over GF 128.<br>(See B.5.4.)                                                                                                                                                                                      | The 15-bit polynominal for the PRBS:<br>$1 + x^{14} + x^{15}$<br>(See Clause 7.1 in [3], C.5.1.)                |         | The 16-bit polynomial for the PRBS:<br>$1 + x + x^3 + x^6 + x^7 + x^{11} + x^{12} + x^{13} + x^{16}$ .<br>(See D.5.1.) |
+|                   | FEC           | Concatenated coding, RS (128, 122) GF 128 with convolutional coding.<br>(See B.5.1.)                                                                                                                                                                                          | RS (204, 188) GF 256<br>(See Clause 7.2 in [3], C.5.2.)                                                         |         | RS (207, 187) GF 256<br>(See D.5.2.)                                                                                   |
+|                   | Interleaving  | Convolutional interleaving depth:<br>$I = 128, 64, 32, 16, 8$<br>$J = 1, 2, 3, 4, 5, 6, 7, 8, 16$ .<br>(See B.5.2.)                                                                                                                                                           | Convolutional interleaving, depth:<br>$I = 12$ .<br>(See Clause 7.3 in [3], C.5.3.)                             |         | Convolutional interleaving, depth: I = 52.<br>(See D.5.3.)                                                             |
+
+**Table 1 – Comparison of specifications in summary form indicating common features**
+
+| Item            |                                 | Annex B                                                      | Annex A                                                 | Annex C                    | Annex D            |
+|-----------------|---------------------------------|--------------------------------------------------------------|---------------------------------------------------------|----------------------------|--------------------|
+| Modu-<br>lation | Byte to symbol mapping          | See B.5.5.                                                   | See Clause 8 in [3], C.6.1.                             |                            | See D.6.1.         |
+|                 | Differential coding             | See B.5.5.                                                   | See Clause 8 in [3], C.6.2.                             |                            | None               |
+|                 | Trellis coding                  | See B.5.5.                                                   |                                                         | None                       |                    |
+|                 | Bandwidth                       | 6 MHz                                                        | 8 MHz                                                   | 6 MHz                      |                    |
+|                 | Constellation                   | 64- or 256-QAM<br>Figure B.18 or B.19                        | 16-, 32-, 64- 128-,<br>256-QAM<br>(See Clause 9 in [3]) | 64-, 256-QAM<br>Figure C.7 | 2-, 4-, 8-, 16-VSB |
+|                 | Roll-off factor                 | 18% or 12% for 64- or<br>256-QAM respectively.<br>See B.6.1. | 15%<br>(See Clause 9 in [3])                            | 13%<br>See C.6.4           | 11.5%<br>See D.6.3 |
+|                 | Baseband filter characteristics | Table B.2                                                    | See Annex A in [3]                                      | Figure C.8                 | Figure D.11        |
+
+# Annex A
+
+## Digital multi-programme System A
+
+(This annex forms an integral part of this Recommendation)
+
+## A.1 Introduction
+
+This annex derives from work done by the Digital Video Broadcasting (DVB) Project, an industry-led consortium of over 260 broadcasters, manufacturers, network operators, software developers, regulatory bodies and others in over 35 countries around the world committed to designing global standards for the global delivery of digital television and data services. It has been adopted by the Joint Technical Committee (JTC) of the European Broadcasting Union (EBU), Comité Européen de Normalization ELECTrotechnique (CENELEC) and the European Telecommunications Standards Institute (ETSI) as European Norm (EN) 300 429 [3].
+
+It describes the framing structure, channel coding and modulation (denoted "the System" for the purposes of this annex) for a digital multi-programme television distribution by cable. The System can be used transparently with the modulation/channel coding system used for digital multi-program television by satellite.
+
+The System is based on MPEG-2 (see Reference [2]) as regards source coding and transport multiplexing with the addition of appropriate Forward Error Correction (FEC). It is based on Quadrature Amplitude Modulation (QAM). It allows for 16-, 32-, 64-, 128-, or 256-QAM constellations.
+
+The System FEC is designed to improve the Bit Error Ratio (BER) from  $10^{-4}$  to a range of  $10^{-10}$  to  $10^{-11}$ , ensuring "Quasi Error Free" (QEF) operation with approximately one uncorrected error event per transmission hour.
+
+## A.2 Specification
+
+The text of ETSI EN 300 429 [3] is applied in this Annex A with the modifications as given below.
+
+#### A.2.1 Un-numbered clause 'Foreword'
+
+The introductory clause labelled 'Foreword' does not apply in the context of this annex.
+
+# Annex B
+
+## Digital multi-programme System B
+
+(This annex forms an integral part of this Recommendation)
+
+## B.1 Introduction
+
+This Annex describes the framing structure, channel coding, and channel modulation for a digital multi-service television distribution system that is specific to a cable channel. The system can be used transparently with the distribution from a satellite channel, as many cable systems are fed directly from satellite links. The specification covers both 64- and 256-QAM. Most features of both modulation schemes are the same. Where there are differences, the specific details for each modulation scheme will be covered.
+
+The design of the modulation, interleaving and coding is based upon testing and characterization of cable systems in North America. The modulation is Quadrature Amplitude Modulation with a 64-point signal constellation (64-QAM) and with a 256-point signal constellation (256-QAM), transmitter selectable. The Forward Error Correction (FEC) is based on a concatenated coding approach that produces high coding gain at moderate complexity and overhead. Concatenated coding offers improved performance over a block code, at a similar overall complexity. The system FEC is optimized for quasi error free operation at a threshold output error event rate of one error event per 15 minutes.
+
+The data format input to the modulation and coding is assumed to be MPEG-2 transport. However, the method used for MPEG synchronization is decoupled from FEC synchronization. For example, this enables the system to carry ATM packets easily without interfering with ATM synchronization. In fact, ATM synchronization may be performed by defined ATM synchronization mechanisms.
+
+There are two modes supported: Mode 1 has a symbol rate of 5.057 Msymbols/s and Mode 2 has a symbol rate of 5.361 Msymbols/s. Typically, Mode 1 will be used for 64-QAM and Mode 2 will be used for 256-QAM. The system will be compatible with future implementations of higher data rate schemes employing higher order QAM extensions.
+
+## B.2 Cable system concept
+
+Channel coding and transmission are specific to a particular medium or communication channel. The expected channel error statistics and distortion characteristics are critical in determining the appropriate error correction and demodulation. The cable channel, including optical fibre, is primarily regarded as a bandwidth-limited linear channel, with a balanced combination of white noise, interference, and multi-path distortion. The Quadrature Amplitude Modulation (QAM) technique used, together with adaptive equalization and concatenated coding is well suited to this application and channel.
+
+The basic layered block diagram of cable transmission processing is shown in Figure B.1. The following subclauses define these layers from the "outside" in, and from the perspective of the transmit side.
+
+![Figure B.1 – Cable transmission block diagram. The diagram shows a 'Transmitter' and a 'Receiver' connected by a 'Channel'. The 'Transmitter' contains 'MPEG framing', 'FEC encoder', and 'QAM modulator'. The 'Receiver' contains 'QAM demodulator', 'FEC decoder', and 'MPEG framing'. The flow is: MPEG-2 transport -> MPEG framing -> FEC encoder -> QAM modulator -> Channel -> QAM demodulator -> FEC decoder -> MPEG framing -> MPEG-2 transport. A label 'T0903400-96/d09' is in the bottom right corner.](4801720824e4b5e2361a5564f91cfb70_img.jpg)
+
+Figure B.1 – Cable transmission block diagram. The diagram shows a 'Transmitter' and a 'Receiver' connected by a 'Channel'. The 'Transmitter' contains 'MPEG framing', 'FEC encoder', and 'QAM modulator'. The 'Receiver' contains 'QAM demodulator', 'FEC decoder', and 'MPEG framing'. The flow is: MPEG-2 transport -> MPEG framing -> FEC encoder -> QAM modulator -> Channel -> QAM demodulator -> FEC decoder -> MPEG framing -> MPEG-2 transport. A label 'T0903400-96/d09' is in the bottom right corner.
+
+**Figure B.1 – Cable transmission block diagram**
+
+## **B.3 MPEG-2 transport layer**
+
+The MPEG-2 transport layer is defined in Reference [2]. The transport layer for MPEG-2 data is comprised of packets having 188 bytes, with one byte for synchronization purposes, three bytes of header containing service identification, scrambling and control information, followed by 184 bytes of MPEG-2 or auxiliary data.
+
+## **B.4 MPEG-2 transport framing**
+
+The MPEG transport framing is the outermost layer of processing. It is provided as a robust means of delivering MPEG packet synchronization to the receiver output. This processing block receives an MPEG-2 transport data stream consisting of a continuous stream of fixed length 188 byte packets. This data stream is transmitted in serial fashion, MSB first. The first byte of a packet is specified to be a sync byte having a value of 47<sub>HEX</sub>.
+
+The sync byte is intended for the purpose of packet delineation. The cable transmission system has incorporated an additional layer of processing to provide an additional functionality by utilizing the information bearing capacity of this sync byte. A parity checksum which is a coset of an FIR parity check linear block code is substituted for this sync byte, supplying improved packet delineation functionality, and error detection capability independent of the FEC layer.
+
+The parity checksum is computed over the adjacent 187 bytes, which constitute the immediately preceding MPEG-2 packet contents (minus sync byte). It is then possible to support simultaneous packet synchronization and error detection. The decoder computes a sliding checksum on the serial data stream, using the detection of a valid code word to detect the start of packet. Once a locked alignment condition is established, the absence of a valid code word at the expected location will indicate a packet error. The error flag of the previous packet may optionally be set as the data is passed out of the decoder. The normal sync word must be re-inserted in place of the checksum to provide a standard MPEG-2 data stream as an output.
+
+The syndrome is computed by passing the 1496 payload bits through a Linear Feedback Shift Register (LFSR) as described by the following equation:
+
+$$f(x) = [1 + x^{1497} b(x)] / g(x)$$
+
+where:
+
+$$g(x) = 1 + x + x^5 + x^6 + x^8; \text{ and}$$
+
+$$b(x) = 1 + x + x^3 + x^7$$
+
+This computational structure is illustrated in Figures B.2 and B.3. All addition operations are assumed to be modulo 2. For an encode operation, the LFSR is first initialized so that all memory elements contain zero value. The 1496 bits which constitute the MPEG-2 transport stream packet payload are then shifted into the LFSR. The encoder input is set to zero after the 1496 data bits are received, and eight additional shifts are required to sequentially output the eight computed syndrome bits. This 8-bit result must then be passed through an additional FIR filtering function  $g(x)$  (initialized to an all-zeros state prior to introduction of the 8 syndrome bits) to generate an encoder checksum. An offset of  $67_{\text{HEX}}$  is added to this checksum result for improved autocorrelation properties, and causes a  $47_{\text{HEX}}$  result to be produced during a syndrome decode operation when a valid code word is present. The final 8-bit checksum with added offset is transmitted MSB first following the 1496 payload bits to implement a systematic encoder.
+
+A parity check matrix may be used by the decoder to identify a valid checksum. A syndrome generator, as shown in Figure B.3, may also be employed for this purpose. The code has been designed such that when the appropriate 188 bytes of the modified MPEG-2 transport stream packet (which includes the associated checksum) are multiplied with the parity check matrix, a valid code word is indicated when the calculated product produces a  $47_{\text{HEX}}$  result. Each of the 8 columns of the parity check matrix "P" includes a 1497 bit vector, hereafter referred to as "C". This vector is defined in Figure B.4.
+
+Proceeding from the leftmost column of the matrix "P", the 1497-bit column "C" is duplicated in subsequent columns of the matrix "P", shifted down by one bit position. The bit positions unoccupied by the column data are filled with zeros, as illustrated in Figure B.5.
+
+Note that the checksum is calculated based on the previous 187 bytes and not the 187 bytes yet to be received by the MPEG-2 sync decoder. This is in contrast to the conventional notion of an MPEG packet structure, in that the sync byte is usually described as the first byte of a received packet.
+
+The received vector "R" is the MPEG-2 data consisting of 187 bytes followed by the checksum byte, yielding a total of 1504 bits. This "R" vector is multiplied (modulo 2) by the parity check "P" matrix, yielding an "S" vector whose length is 8-bits, as illustrated in Figure B.6.
+
+![Figure B.2: Checksum generator for the MPEG-2 sync byte encoder. The diagram shows a complex feedback loop with multiple delay elements (Z^-1) and XOR gates. An input line enters from the left. A switch can be set to position A (first 1496 shifts) or position B (last 8 shifts). The output of the switch is fed into a series of 8 XOR gates, each also receiving a constant input ('1' or '0'). The outputs of these XOR gates are labeled b0 through b7, representing the encoder checksum output from LSB to MSB. A Z-1497 delay element is also part of the feedback loop. Reference T0903410-96/d10 is noted at the bottom right.](fa859e4e468bfb2710a94527f2c504af_img.jpg)
+
+Input
+
+Switch position A – first 1496 shifts  
+Switch position B – last 8 shifts
+
+'0' B A '0'
+
+67<sub>HEX</sub> offset, MSB first
+
+'1' '1' '1' '0' '0' '1' '1' '0'
+
+b<sub>0</sub> b<sub>1</sub> b<sub>2</sub> b<sub>3</sub> b<sub>4</sub> b<sub>5</sub> b<sub>6</sub> b<sub>7</sub>
+
+(LSB) Encoder checksum output (MSB)
+
+T0903410-96/d10
+
+Figure B.2: Checksum generator for the MPEG-2 sync byte encoder. The diagram shows a complex feedback loop with multiple delay elements (Z^-1) and XOR gates. An input line enters from the left. A switch can be set to position A (first 1496 shifts) or position B (last 8 shifts). The output of the switch is fed into a series of 8 XOR gates, each also receiving a constant input ('1' or '0'). The outputs of these XOR gates are labeled b0 through b7, representing the encoder checksum output from LSB to MSB. A Z-1497 delay element is also part of the feedback loop. Reference T0903410-96/d10 is noted at the bottom right.
+
+**Figure B.2 – Checksum generator for the MPEG-2 sync byte encoder**
+
+![Figure B.3: Syndrome generator for the MPEG-2 sync decoder. This diagram is similar to Figure B.2 but with a different feedback configuration. The input line enters from the right. The output of the main feedback loop is labeled 'Decoder syndrome output'. Reference T0903420-96/d11 is noted at the bottom right.](0f985b39edc1d52ba3600c438bc8f0a5_img.jpg)
+
+Input
+
+Decoder syndrome output
+
+T0903420-96/d11
+
+Figure B.3: Syndrome generator for the MPEG-2 sync decoder. This diagram is similar to Figure B.2 but with a different feedback configuration. The input line enters from the right. The output of the main feedback loop is labeled 'Decoder syndrome output'. Reference T0903420-96/d11 is noted at the bottom right.
+
+**Figure B.3 – Syndrome generator for the MPEG-2 sync decoder**
+
+![](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg)
+
+$C = 1497 \times 1 =$
+
+$C_{0,0}$   
+ $C_{1,0}$   
+ $C_{2,0}$   
+ $\vdots$   
+ $C_{1494,0}$   
+ $C_{1495,0}$   
+ $C_{1496,0}$
+
+$C = 1497 \times 1 =$
+
+|      |      |      |      |      |      |      |      |      |                           |
+|------|------|------|------|------|------|------|------|------|---------------------------|
+| b0f3 | 1039 | d741 | 068e | 9fb9 | bd28 | b445 | 8c12 | 1e70 | 0724                      |
+| 857f | 2627 | 9546 | f166 | 9ec8 | 6edf | 23e0 | da9a | aff2 | c4ea                      |
+| 97a5 | 5688 | b182 | c3ce | 40e4 | 5d06 | 2e3b | 7ee6 | f4a1 | d114                      |
+| 0ddb | a47c | 5b53 | 15fe | 989d | 551a | c59b | 7b21 | bb7d | 8f<br><sup>1</sup> binary |
+| eba0 | 05c7 | 4fdc | 5e94 | 5a22 | c609 | 0f38 | 0392 | 7419 |                           |
+| caa3 | 78b3 | cf64 | 376f | 91f0 | 6d4d | 57f9 | 6275 | 546b |                           |
+| 58c1 | 61e7 | 2072 | ae83 | 171d | 3f73 | 7a50 | 688a | 1825 |                           |
+| 2da9 | 0aff | 4c4e | 2a8d | e2cd | 3d90 | ddbe | 47c0 | b534 |                           |
+| a7ee | 2f4a | ad11 | 6304 | 879c | 81c9 | ba0c | 5c77 | fdcc |                           |
+| 67b2 | 1bb7 | 48f8 | b6a6 | 2bfc | 313a | aa35 | 8b36 | f642 |                           |
+
+All entries are in hexadecimal format except where otherwise noted.
+
+T0903430-96/d12
+
+Figure B.4 – "C" column vector (replicated inside the parity check matrix)
+
+![](2cde062fd82833415971a8bd1a2cafab_img.jpg)
+
+"P" parity check matrix
+
+1497 rows (bits)
+
+C
+
+|   |   |   |   |   |   |   |   |
+|---|---|---|---|---|---|---|---|
+| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+| 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
+
+7 rows (bits)
+
+= 1504 × 8 = P
+
+8 columns
+
+T0903440-96/d13
+
+Figure B.5 – Structure of the parity check matrix "P"
+
+![Diagram showing the multiplication of an R 'Vector' (Alignment window) of size 1 x 1504 and a P 'Matrix' (Parity check) of size 1504 x 8 to produce an S 'Vector' (Received checksum) of size 1 x 8. The result is S = [0100 0111] = 0x47. A reference code T0903450-96/d14 is present.](76b0cd79baaedd942af4dc42f2e764b8_img.jpg)
+
+$$\begin{bmatrix} \text{R "Vector"} \\ \text{(Alignment window)} \\ 1 \times 1504 \end{bmatrix} \times \begin{bmatrix} \text{P "Matrix"} \\ \text{(Parity check)} \\ 1504 \times 8 \end{bmatrix} = \begin{bmatrix} \text{S "Vector"} \\ \text{(Received checksum)} \\ 1 \times 8 \end{bmatrix}$$
+
+$$S = [0100\ 0111] = 0 \times 47$$
+
+T0903450-96/d14
+
+Diagram showing the multiplication of an R 'Vector' (Alignment window) of size 1 x 1504 and a P 'Matrix' (Parity check) of size 1504 x 8 to produce an S 'Vector' (Received checksum) of size 1 x 8. The result is S = [0100 0111] = 0x47. A reference code T0903450-96/d14 is present.
+
+**Figure B.6 – Received MPEG-2 vector and parity check matrix multiplication**
+
+A valid check sum is indicated when  $S = [0100, 0111] = 47_{\text{HEX}}$ .
+
+For carriage of transport protocols other than MPEG-2 Transport, e.g., ATM, this outer layer is removed or bypassed. The FEC layer accepts and delivers data without any constraints on protocol. The framing section could be replaced with one appropriate to the alternative transport protocol if required by an application. All other portions of this specification (modulation, coding, interleaving) are implemented as described below. For the case of ATM, no framing layer is required. The ATM HEC typically provides adequate packet framing and error detection. Isochronous ATM streams are therefore carried transparently without overhead for MPEG or quasi-MPEG packet encapsulation.
+
+## **B.5 Forward error correction**
+
+The Forward Error Correction (FEC) definition is composed of four processing layers, as illustrated in Figure B.7. There are no dependencies on input data protocol in any of the FEC layers. FEC synchronization is fully internal and transparent. Any data sequence will be delivered from the encoder input to decoder output.
+
+![Diagram illustrating the layers of processing in the FEC, divided into FEC encoding and FEC decoding. The layers are nested: Reed-Solomon layer (outermost), Interleaving layer, Randomization layer, and Trellis layer (innermost). The sequence of blocks is: Reed-Solomon encoder, Inter-leaver, Ran-domizer, Trellis encoder, Channel, Trellis decoder, De-ran-domizer, De-interleaver, and Reed-Solomon decoder. A reference code T0903460-96/d15 is present.](8592a32c2fdf17c1e562f0ba6b7e8e1a_img.jpg)
+
+T0903460-96/d15
+
+Diagram illustrating the layers of processing in the FEC, divided into FEC encoding and FEC decoding. The layers are nested: Reed-Solomon layer (outermost), Interleaving layer, Randomization layer, and Trellis layer (innermost). The sequence of blocks is: Reed-Solomon encoder, Inter-leaver, Ran-domizer, Trellis encoder, Channel, Trellis decoder, De-ran-domizer, De-interleaver, and Reed-Solomon decoder. A reference code T0903460-96/d15 is present.
+
+**Figure B.7 – Layers of processing in the FEC**
+
+The FEC section uses various types of error correcting algorithms and interleaving techniques to transport data reliably over the cable channel.
+
+- Reed-Solomon (RS) Coding – Provides block encoding and decoding to correct up to three symbols within an RS block.
+- Interleaving – Evenly disperses the symbols, protecting against a burst of symbol errors from being sent to the RS decoder.
+- Randomization – Randomizes the data on the channel to allow effective QAM demodulator synchronization.
+- Trellis Coding – Provides convolutional encoding and with the possibility of using soft decision trellis decoding of random channel errors.
+
+The following subclauses define these 4 layers.
+
+#### B.5.1 Reed-Solomon coding
+
+The MPEG-2 transport stream is Reed-Solomon (RS) encoded using a (128, 122) code over GF(128). This code has the capability of correcting up to  $t = 3$  symbol errors per RS block. The same RS code is used for both 64-QAM and 256-QAM. However, the FEC frame format is different for each modulation type, as described in a later subclause.
+
+The Reed-Solomon encoder implementation is described in this subclause. A systematic encoder is utilized to implement a  $t = 3$ , (128,122) extended Reed-Solomon code over GF(128). The primitive polynomial used to form the field over GF(128) is:
+
+$$p(x) = x^7 + x^3 + 1$$
+
+where:
+
+$$p(x) = 0$$
+
+The generator polynomial used by the encoder is:
+
+$$\begin{aligned} g(x) &= (x + \alpha)(x + \alpha^2)(x + \alpha^3)(x + \alpha^4)(x + \alpha^5) \\ &= x^5 + \alpha^{52}x^4 + \alpha^{116}x^3 + \alpha^{119}x^2 + \alpha^{61}x + \alpha^{15} \end{aligned}$$
+
+The message polynomial input to the encoder consists of 122, 7-bit symbols, and is described below:
+
+$$m(x) = m_{121}x^{121} + m_{120}x^{120} + \dots + m_1x + m_0$$
+
+This message polynomial is first multiplied by  $x^5$ , then divided by the generator polynomial  $g(x)$  to form a remainder, described by the following:
+
+$$r(x) = r_4x^4 + r_3x^3 + r_2x^2 + r_1x + r_0$$
+
+This remainder constitutes five parity symbols which are then added to the message polynomial to form a 127-symbol code word that is an even multiple of the generator polynomial.
+
+The generated code word is now described by the following polynomial:
+
+$$c(x) = m_{121}x^{126} + m_{120}x^{125} + m_{119}x^{124} + \dots + r_4x^4 + r_3x^3 + r_2x^2 + r_1x + r_0$$
+
+A valid code word will have roots at the first through fifth powers of  $\alpha$ .
+
+An extended parity symbol ( $c\_$ ) is generated by evaluating the code word at the sixth power of  $\alpha$ .
+
+$$c\_ = c(\alpha^6)$$
+
+This extended symbol is used to form the last symbol of a transmitted Reed-Solomon block. The extended code word then appears as follows:
+
+$$\begin{aligned}\hat{c} &= xc(x) + c_- \\ &= m_{121}x^{127} + m_{120}x^{126} + \dots + m_1x^7 + m_0x^6 + r_4x^5 + r_3x^4 + r_2x^3 + r_1x^2 + r_0x + c_-\end{aligned}$$
+
+The structure of a Reed-Solomon block which illustrates the order of transmitted symbols output from the RS encoder is shown below:
+
+$$m_{121}m_{120}m_{119} \dots m_1m_0r_4r_3r_2r_1r_0c_- \text{ (order sent is left to right)}$$
+
+#### B.5.2 Interleaving
+
+Interleaving is included in the modem between the RS block coding and the randomizer to enable the correction of burst noise induced errors. In both 64-QAM and 256-QAM a convolutional interleaver is employed.
+
+Convolutional interleaving is illustrated in Figure B.8. At the start of an FEC frame defined in a subsequent subclause, the interleaving commutator position is initialized to the top-most branch and increments at the RS symbol frequency, with a single symbol output from each position. With a convolutional interleaver, the RS code symbols are sequentially shifted into the bank of I registers (the width of each register is 7 bits which matches the RS symbol size). Each successive register has J symbols more storage than the preceding register. The first interleaver path has zero delay, the second has a J symbol period of delay, the third 2\*J symbol periods of delay, and so on, upto the I<sup>th</sup> path which has (I - 1)\*J symbol periods of delay. This is reversed for the de-interleaver in the Cable Decoder such that the net delay of each RS symbol is the same through the interleaver and de-interleaver. Burst noise in the channel causes a series of bad symbols. These are spread over many RS blocks by the de-interleaver such that the resultant symbol errors per block are within the range of the RS decoder correction capability.
+
+![Figure B.8 – Interleaving functional block diagram. The diagram shows an Interleaver and a De-interleaver connected by a Channel. The Interleaver has I paths, each with a commutator and a bank of J registers. The De-interleaver has the same structure but reversed. The output of the De-interleaver is 7 bits. A legend below the diagram defines the symbol delay (I, J) for various modes.](e636d7ccca0ad14c6b95201404324823_img.jpg)
+
+Symbol delay  
+(I, J) = (128, 1), (64, 2), (32, 4), (16, 8), (8, 16)  
+(reduced interleaving modes)  
+I = 128, J = 1 to 8  
+(enhanced interleaving modes)
+
+T0903470-96/d16
+
+Figure B.8 – Interleaving functional block diagram. The diagram shows an Interleaver and a De-interleaver connected by a Channel. The Interleaver has I paths, each with a commutator and a bank of J registers. The De-interleaver has the same structure but reversed. The output of the De-interleaver is 7 bits. A legend below the diagram defines the symbol delay (I, J) for various modes.
+
+Figure B.8 – Interleaving functional block diagram
+
+With regard to interleaving capability, two distinct operating modes are specified, hereafter referred to as *level 1* and *level 2*.
+
+*Level 1* is specified for 64-QAM transmission only. This mode accommodates the installed base of legacy 64-QAM-only digital set tops. While operating in level 1, a single interleaving depth will be supported; namely  $I = 128$ ,  $J = 1$ .
+
+*Level 2* shall encompass 64-QAM and 256-QAM transmission, and will for both modulation schemes be capable of supporting variable interleaving. This will include both enlarged and reduced interleaving depths relative to the nominal 64-QAM (level 1) configuration. Four data bits are transmitted in-band during the FEC frame sync interval to convey the interleaving parameters to the receiver for a given channel.
+
+Table B.1 describes the interleaver parameters for level 1 operation, with associated latency and burst protection. Table B.2 describes the decoding of the 4-bit in-band control word into the  $I$  and  $J$  interleaving parameters for level 2 operation, also with associated burst protection and latency.
+
+**Table B.1 – Level 1 interleaving**
+
+| Control word (4 bits) | $I$ (# of taps) | $J$ (increment) | Burst protection | Latency |
+|-----------------------|-----------------|-----------------|------------------|---------|
+| xxxx                  | 128             | 1               | 95 $\mu\text{s}$ | 4.0 ms  |
+
+**Table B.2 – Level 2 interleaving**
+
+| Control word (4 bits) | $I$ (# of taps) | $J$ (increment) | Burst protection 64-QAM/256-QAM      | Latency 64-QAM/256-QAM |
+|-----------------------|-----------------|-----------------|--------------------------------------|------------------------|
+| 0001                  | 128             | 1               | 95 $\mu\text{s}$ /66 $\mu\text{s}$   | 4.0 ms/2.8 ms          |
+| 0011                  | 64              | 2               | 47 $\mu\text{s}$ /33 $\mu\text{s}$   | 2.0 ms/1.4 ms          |
+| 0101                  | 32              | 4               | 24 $\mu\text{s}$ /16 $\mu\text{s}$   | 0.98 ms/0.68 ms        |
+| 0111                  | 16              | 8               | 12 $\mu\text{s}$ /8.2 $\mu\text{s}$  | 0.48 ms/0.33 ms        |
+| 1001                  | 8               | 16              | 5.9 $\mu\text{s}$ /4.1 $\mu\text{s}$ | 0.22 ms/0.15 ms        |
+| 1011                  | Reserved        |                 |                                      |                        |
+| 1101                  | Reserved        |                 |                                      |                        |
+| 1111                  | Reserved        |                 |                                      |                        |
+| 0000                  | 128             | 1               | 95 $\mu\text{s}$ /66 $\mu\text{s}$   | 4.0 ms/2.8 ms          |
+| 0010                  | 128             | 2               | 190 $\mu\text{s}$ /132 $\mu\text{s}$ | 8.0 ms/5.6 ms          |
+| 0100                  | 128             | 3               | 285 $\mu\text{s}$ /198 $\mu\text{s}$ | 12 ms/8.4 ms           |
+| 0110                  | 128             | 4               | 379 $\mu\text{s}$ /264 $\mu\text{s}$ | 16 ms/11 ms            |
+| 1000                  | 128             | 5               | 474 $\mu\text{s}$ /330 $\mu\text{s}$ | 20 ms/14 ms            |
+| 1010                  | 128             | 6               | 569 $\mu\text{s}$ /396 $\mu\text{s}$ | 24 ms/17 ms            |
+| 1100                  | 128             | 7               | 664 $\mu\text{s}$ /462 $\mu\text{s}$ | 28 ms/19 ms            |
+| 1110                  | 128             | 8               | 759 $\mu\text{s}$ /528 $\mu\text{s}$ | 32 ms/22 ms            |
+
+#### B.5.3 Frame synchronization sequence
+
+The frame synchronization sequence trailer delineates the FEC frame, providing synchronized RS coding, interleaving, and randomization. Additionally, trellis groups for 256-QAM only are aligned with the FEC frame. The FEC framing does not perform MPEG packet of trellis decoder synchronization. The RS block and 7-bit symbol structures are aligned with the end of the frame for both 64- and 256-QAM.
+
+For 64-QAM, an FEC frame consists of a 42-bit sync trailer which is appended to the end of 60 RS blocks, with each RS block containing 128 symbols. Each RS symbol consists of 7 bits. Thus, there is a total of 53 760 data bits and 42 frame sync trailer bits in this FEC frame. The first 4 7-bit symbols of the frame sync trailer contain the 28-bit "unique" synchronization pattern (1110101 0101100 0001101 1101100) or (75 2C 0D 6C)<sub>HEX</sub>. The remaining 2 symbols (14 bits) are utilized as follows: first 4 bits for interleaver mode control, and 10 bits are reserved and set to zero. The frame sync trailer is inserted by the encoder and detected at the decoder. The decoder circuits search for this pattern and determine the location of the frame boundary and interleaver depth mode when found. The FEC frame for 64-QAM is shown in Figure B.9.
+
+![Diagram of the frame packet format for 64-QAM showing RS blocks followed by a sync trailer.](e180f2b5fcbe8001554a7c0677cd3f82_img.jpg)
+
+```
+
+graph LR
+    subgraph FEC_Frame [FEC frame contains both A and B information]
+        RS1[Reed-Solomon block # 1  
+122 symbols] --> P1[6 RS parity symbols]
+        P1 --> RS2[Reed-Solomon block # 2  
+122 symbols]
+        RS2 --> P2[6 RS parity symbols]
+        P2 --> Dots[...] 
+        Dots --> RS60[Reed-Solomon block # 60  
+122 symbols]
+        RS60 --> P60[6 RS parity symbols]
+        P60 --> SyncTrailer[6 RS symbols sync trailer 42 bits]
+    end
+
+    subgraph Sync_Trailer_Detail [FSYNC word]
+        S1[1110101] --- S2[0101100] --- S3[0001101] --- S4[1101100] --- CW[4-bit control word] --- RB[10 reserved bits]
+    end
+
+    SyncTrailer -.-> Sync_Trailer_Detail
+    S1 --- S4 -.-> USP[Unique sync. pattern 75 2C 0D 6C HEX]
+    CW --- RB -.-> TwoRS[2 RS symbols]
+
+```
+
+The diagram illustrates the structure of an FEC frame for 64-QAM. It shows a series of Reed-Solomon (RS) blocks, labeled 'Reed-Solomon block # 1', 'Reed-Solomon block # 2', and 'Reed-Solomon block # 60'. Each block contains 122 symbols followed by 6 RS parity symbols. The blocks are part of an 'FEC frame (contains both "A" and "B" information)'. Following the 60th block is a '6 RS symbols sync trailer (42 bits)'. A detailed view of this trailer (labeled 'FSYNC word') shows it is composed of several 7-bit symbols: '1110101', '0101100', '0001101', '1101100', followed by a 4-bit control word and 10 reserved bits. The first four symbols constitute the 'Unique sync. pattern (75 2C 0D 6C)<sub>HEX</sub>'. The last two symbols contain the '4-bit control word' and '10 reserved bits'.
+
+Diagram of the frame packet format for 64-QAM showing RS blocks followed by a sync trailer.
+
+**Figure B.9 – Frame packet format for 64-QAM**
+
+For 256-QAM, an FEC frame consists of a 40-bit sync trailer which is appended to the end of 88 RS blocks, with each RS block containing 128 symbols. Each RS symbol consists of 7 bits. Thus, there is a total of 78 848 data bits and 40 frame sync trailer bits in this FEC frame. The 40-bit frame sync trailer is divided as follows: 32 bits are the "unique" synchronization pattern (0111 0001 1110 1000 0100 1101 1101 0100) or (71 E8 4D D4)<sub>HEX</sub>, 4 bits are a control word which determine the size of the interleaver employed, and 4 bits are a reserved word which is set to zero. The FEC frame for 256-QAM is shown in Figure B.10.
+
+Note that there is no synchronization relationship between the transmitted RS block and transport data packets. Thus, MPEG-2 transport stream packet synchronization is obtained independently from RS frame synchronization. This keeps the FEC and transport layers de-coupled and independent.
+
+![Figure B.10 – Frame packet format for 256-QAM. The diagram shows the structure of an FEC frame over time. The frame consists of multiple Reed-Solomon blocks (labeled #1, #2, ..., #88). Each block contains 122 symbols, followed by 6 RS parity symbols. The frame ends with a 40-bit frame sync trailer. A detailed view of the trailer shows it is composed of 10 7-bit words. The first 8 words (0111, 0001, 1110, 1000, 0100, 1101, 1101, 0100) form the 'Unique word (71 E8 4D D4)'. The 9th word is a '4-bit control word' followed by 3 'Reserved bits'. The 10th word is '0000'. The entire 40-bit trailer is labeled 'Frame sync trailer'.](c914f51f4427bc672dd0526cfc90ebe9_img.jpg)
+
+Figure B.10 – Frame packet format for 256-QAM. The diagram shows the structure of an FEC frame over time. The frame consists of multiple Reed-Solomon blocks (labeled #1, #2, ..., #88). Each block contains 122 symbols, followed by 6 RS parity symbols. The frame ends with a 40-bit frame sync trailer. A detailed view of the trailer shows it is composed of 10 7-bit words. The first 8 words (0111, 0001, 1110, 1000, 0100, 1101, 1101, 0100) form the 'Unique word (71 E8 4D D4)'. The 9th word is a '4-bit control word' followed by 3 'Reserved bits'. The 10th word is '0000'. The entire 40-bit trailer is labeled 'Frame sync trailer'.
+
+**Figure B.10 – Frame packet format for 256-QAM**
+
+#### B.5.4 Randomization
+
+The randomizer shown in Figure B.11 is the third layer of processing in the FEC block diagram. The randomizer provides for even distribution of the symbols in the constellation, which enables the demodulator to maintain proper lock. The randomizer adds a Pseudorandom Noise (PN) sequence of 7-bit symbols over GF(128) (i.e., bit-wise exclusive-OR) to the symbols within the FEC frame to assure a random transmitted sequence.
+
+For both 64- and 256-QAM, the randomizer is initialized during the FEC frame trailer, and is enabled at the first symbol after the trailer. Thus the trailer itself is not randomized, and the initialized output value randomizes the first data symbol.
+
+Initialization is defined as pre-loading to the 'all ones' state for the randomizer structure shown in Figure B.11. The randomizer uses a linear feedback shift register specified by a GF(128) polynomial defined as follows:
+
+$$f(x) = x^3 + x + \alpha^3$$
+
+where:
+
+$$\alpha^7 + \alpha^3 + 1 = 0$$
+
+![Block diagram of a 7-bit symbol randomizer. The input 'Data in' (7 bits) is summed with a feedback signal at a summer. The output of this summer is passed through three cascaded delay blocks, each labeled Z^-1. The output of the third delay block is labeled 'Data out' (7 bits). A tap from the output of the third delay block is fed back through a gain block labeled alpha^3 and then summed with the input 'Data in' at the first summer. Below the diagram, the text 'The randomizer polynomial' is shown, followed by a box containing the equation f(x) = x^3 + x + alpha^3. The identifier T0903500-96/d19 is also present.](c5452f95f3b28f1bfe29e84fbc2e1267_img.jpg)
+
+The randomizer polynomial
+
+$$f(x) = x^3 + x + \alpha^3$$
+
+T0903500-96/d19
+
+Block diagram of a 7-bit symbol randomizer. The input 'Data in' (7 bits) is summed with a feedback signal at a summer. The output of this summer is passed through three cascaded delay blocks, each labeled Z^-1. The output of the third delay block is labeled 'Data out' (7 bits). A tap from the output of the third delay block is fed back through a gain block labeled alpha^3 and then summed with the input 'Data in' at the first summer. Below the diagram, the text 'The randomizer polynomial' is shown, followed by a box containing the equation f(x) = x^3 + x + alpha^3. The identifier T0903500-96/d19 is also present.
+
+**Figure B.11 – Randomizer (7-bit symbol)**
+
+#### B.5.5 Trellis coded modulation
+
+As part of the concatenated coding scheme, trellis coding is employed for the inner code. It allows the introduction of redundancy to improve the threshold Signal-to-Noise Ratio (SNR) by increasing the symbol constellation without increasing the symbol rate. As such, it is more properly termed "trellis coded modulation".
+
+##### B.5.5.1 64-QAM modulation mode
+
+For 64-QAM, the input to the trellis coded modulator is a 28-bit sequence of four, 7-bit RS symbols, which are labelled in pairs of 'A' symbols, and 'B' symbols. A block diagram of a 64-QAM trellis coded modulator is shown in Figure B.12. All 28 bits are assigned to a trellis group, where each trellis group forms 5-QAM symbols, as shown in Figure B.13.
+
+Of the 28 input bits that form a trellis group, each of two groups of 4 bits of the differentially pre-coded bit streams in a trellis group are separately encoded by a Binary Convolutional Coder (BCC). Each BCC produces 5 coded bits, as shown in Figure B.12. The remaining bits are sent to the mapper uncoded. This will produce an overall output of 30 bits. Thus, the overall code rate for 64-QAM trellis coded modulation is 14/15.
+
+The trellis group is formed from RS symbols as follows: For the "A" symbols, the RS symbols are read, from MSB to LSB,  $A_{10}, A_8, A_7, A_5, A_4, A_2, A_1$  and  $A_9, A_6, A_3, A_0, A_{13}, A_{12}, A_{11}$ . The four MSBs of the second symbol are input to the BCC, one bit at a time, LSB first. The remaining bits of the second symbol and all the bits of the first symbol are input to the mapper, uncoded, LSB first one bit at a time. The four bits sent to the BCC will produce 5 coded bits labelled,  $U_1, U_2, U_3, U_4, U_5$ . The same process is done for the "B" bits. The process can be seen in Figure B.12. With 64-QAM, 4 RS symbols conveniently fit into one trellis group, and in this case the sync word may occupy every bit position within a trellis group.
+
+![Block diagram of a 64-QAM trellis coded modulator. The input is a 28-bit data stream from a randomizer. A parser splits this into MSBs and LSBs of 'A' and 'B'. The MSBs are uncoded and mapped directly. The LSBs are processed through a differential pre-coder and then a (1/2) binary convolutional coder with (4/5) puncture to produce coded bits. These are then mapped by a QAM mapper to produce the 64-QAM output. A note indicates the overall rate is 14/15.](7133ccf78043568ca62ecbcd43628a4a_img.jpg)
+
+The diagram illustrates the internal structure of a 64-QAM trellis coded modulator. The input is a 28-bit data stream from a randomizer, which is first processed by a Buffer. The Parser then splits the data into four groups: MSBs of "A" ( $A_{13}, A_{11}, A_8, A_5, A_2$  and  $A_{13}, A_{10}, A_7, A_4, A_1$ ), MSBs of "B" ( $B_{13}, B_{11}, B_8, B_5, B_2$  and  $B_{13}, B_{10}, B_7, B_4, B_1$ ), LSB of "A" ( $A_9, A_6, A_3, A_0$ ), and LSB of "B" ( $B_9, B_6, B_3, B_0$ ). The MSBs are uncoded and mapped directly to  $C^5, C^4, C^2, C^1$ . The LSBs are processed through a Differential pre-coder (producing  $W, X, Z, Y$ ) and then a (1/2) Binary convolutional coder with (4/5) puncture to produce coded bits  $U_5, U_4, U_3, U_2, U_1$  and  $V_5, V_4, V_3, V_2, V_1$ , which are mapped to  $C^3$  and  $C^0$ . A note indicates that every 4-bit sequential input yields a 5-bit sequential output. The overall rate is 14/15. The QAM mapper produces the final 64-QAM output. A Time axis arrow points to the left.
+
+Block diagram of a 64-QAM trellis coded modulator. The input is a 28-bit data stream from a randomizer. A parser splits this into MSBs and LSBs of 'A' and 'B'. The MSBs are uncoded and mapped directly. The LSBs are processed through a differential pre-coder and then a (1/2) binary convolutional coder with (4/5) puncture to produce coded bits. These are then mapped by a QAM mapper to produce the 64-QAM output. A note indicates the overall rate is 14/15.
+
+T0903510-96/d20
+
+**Figure B.12 – 64-QAM trellis coded modulator block diagram**
+
+![Figure B.13: 64-QAM trellis group diagram. The top part shows a grid of 28 bits arranged in 5 columns (T0 to T4) and 6 rows. The columns are labeled 'QAM symbols' at the top. The rows are labeled 'Bits input to BCC' on the left. The bottom part shows a horizontal sequence of 28 bits divided into four RS symbols (RS0, RS1, RS2, RS3). The bits are labeled from MSB to LSB: A10, A8, A7, A5, A4, A2, A1, A9, A6, A3, A0, A13, A12, A11, B10, B8, B7, B5, B4, B2, B1, B9, B6, B3, B0, B13, B12, B11. Arrows indicate the order of RS symbols and the mapping to trellis groups.](cbdfdade780e677eb1c1aef3081ce9ef_img.jpg)
+
+28 bits
+
+Order of RS symbols
+
+T0903520-96/d21
+
+RS symbol to Trellis Group bit ordering
+
+Figure B.13: 64-QAM trellis group diagram. The top part shows a grid of 28 bits arranged in 5 columns (T0 to T4) and 6 rows. The columns are labeled 'QAM symbols' at the top. The rows are labeled 'Bits input to BCC' on the left. The bottom part shows a horizontal sequence of 28 bits divided into four RS symbols (RS0, RS1, RS2, RS3). The bits are labeled from MSB to LSB: A10, A8, A7, A5, A4, A2, A1, A9, A6, A3, A0, A13, A12, A11, B10, B8, B7, B5, B4, B2, B1, B9, B6, B3, B0, B13, B12, B11. Arrows indicate the order of RS symbols and the mapping to trellis groups.
+
+**Figure B.13 – 64-QAM trellis group**
+
+##### B.5.5.2 256-QAM modulation mode
+
+For 256-QAM, an analogous trellis coding is employed using the same BCC as 64-QAM, with the same rate 1/2 generator and the same 4/5 puncture matrix. The 256-QAM trellis coded modulator is shown in Figure B.14. In this case all the FEC frame sync information is embedded only in the trellis group convolutionally encoded bit positions of a trellis group as shown in Figure B.15.
+
+There are two distinct types of trellis groups in 256-QAM: hereafter referred to as a *non-sync* group and a *sync* group. Each trellis group generates 5-QAM symbols at the modulator, the non-sync group contains 38 data bits while the sync group contains 30 data bits and 8 sync bits. Figure B.15 shows both a non-sync trellis group and a sync trellis group. Since there are 88 RS blocks plus 40 frame sync bits per FEC frame, there will be a total of 2076 trellis groups per frame. Of these trellis groups, 2071 are non-sync trellis groups and 5 are sync trellis groups. The 5 sync trellis groups come at the end of the frame. The frame sync trailer is aligned to the trellis groups. In the encoder, the trellis group is further divided into two groups: one uncoded bit stream and one coded bit stream. The MSB of the first RS symbol in the FEC frame is assigned to the first bit in the first non-sync trellis group, as shown in the ordering in Figure B.15. The output from each BCC is the five parity bits labelled  $U_1$  through  $U_5$  and  $V_1$  through  $V_5$ , respectively, as shown in Figure B.14.
+
+![Block diagram of a 256-QAM trellis coded modulator. A 38-bit data stream enters a Data Formatter. MSBs of A and B are uncoded and mapped to C7, C6, C5, C3, C2, C1. LSBs of A and B pass through a Differential Pre-coder and then through (1/2) Binary convolutional coders with (4/5 puncture) to produce coded outputs for C4 and C0. All signals enter a QAM mapper to produce a 256-QAM output.](aaf3e6e44cdeabd6d1df869c5f392ea1_img.jpg)
+
+Uncoded
+
+Time ←
+
+MSBs of 'A'
+
+$A_{18}, A_{15}, A_{11}, A_7, A_3$  →  $C^7$
+
+$A_{17}, A_{14}, A_{10}, A_6, A_2$  →  $C^6$
+
+$A_{16}, A_{13}, A_9, A_5, A_1$  →  $C^5$
+
+MSBs of 'B'
+
+$B_{18}, B_{15}, B_{11}, B_7, B_3$  →  $C^3$
+
+$B_{17}, B_{14}, B_{10}, B_6, B_2$  →  $C^2$
+
+$B_{16}, B_{13}, B_9, B_5, B_1$  →  $C^1$
+
+Data stream from randomizer  
+38 bits →
+
+Data formatter
+
+Coded
+
+LSB of 'A'
+
+$A_{12}, A_8, A_4, A_0$   
+( $S_6, S_4, S_2, S_0$ )
+
+W → X
+
+(1/2) Binary convolutional coder with (4/5 puncture)
+
+$U_5, U_4, U_3, U_2, U_1$  →  $C^4$
+
+Differential pre-coder
+
+LSB of 'B'
+
+$B_{12}, B_8, B_4, B_0$   
+( $S_7, S_5, S_3, S_1$ )
+
+Z → Y
+
+(1/2) Binary convolutional coder with (4/5 puncture)
+
+$V_5, V_4, V_3, V_2, V_1$  →  $C^0$
+
+Every 4-bit sequential input yields a 5-bit sequential output
+
+The overall rate is 19/20
+
+QAM mapper
+
+256-QAM output
+
+Block diagram of a 256-QAM trellis coded modulator. A 38-bit data stream enters a Data Formatter. MSBs of A and B are uncoded and mapped to C7, C6, C5, C3, C2, C1. LSBs of A and B pass through a Differential Pre-coder and then through (1/2) Binary convolutional coders with (4/5 puncture) to produce coded outputs for C4 and C0. All signals enter a QAM mapper to produce a 256-QAM output.
+
+T0903530-96/d22
+
+**Figure B.14 – 256-QAM trellis coded modulator block diagram**
+
+![Figure B.15: 256-QAM sync and non-sync trellis groups. The diagram shows two trellis group structures. The 'Non-sync trellis group' is a 5x8 grid of QAM symbols with columns T0 to T4 and rows containing symbols like B3, B7, B11, B15, B18. The 'Sync trellis group' is similar but includes 'Sync bits' S0, S1, S2, S3, S4, S5, S6, S7 in the bottom two rows. Below the grids, two horizontal bit sequences are shown: 'Non-sync trellis group bit order' (A0, B0, A1, A2, A3, B1, B2, B3, A4, B4, A5, A6, A7, B5, B6, B7, A8, B8, A9, A10, A11, B9, B10, B11, A12, B12, A13, A14, A15, B13, B14, B15, A16, A17, A18, B16, B17, B18) and 'Sync trellis group bit order' (S0, S1, A1, A2, A3, B1, B2, B3, S2, S3, A5, A6, A7, B5, B6, B7, S4, S5, A9, A10, A11, B9, B10, B11, S6, S7, A13, A14, A15, B13, B14, B15, A16, A17, A18, B16, B17, B18). A note states 'A0 is assigned to the MSB of the first RS symbol in the FEC frame'. A 'Time' arrow points right, and a '38 bits' scale bar is shown.](8c348bf9c2c81b018017ae1d19506a9a_img.jpg)
+
+QAM symbols
+
+T<sub>0</sub> T<sub>1</sub> T<sub>2</sub> T<sub>3</sub> T<sub>4</sub>
+
+B<sub>3</sub> B<sub>7</sub> B<sub>11</sub> B<sub>15</sub> B<sub>18</sub>
+
+B<sub>2</sub> B<sub>6</sub> B<sub>10</sub> B<sub>14</sub> B<sub>17</sub>
+
+B<sub>1</sub> B<sub>5</sub> B<sub>9</sub> B<sub>13</sub> B<sub>16</sub>
+
+A<sub>3</sub> A<sub>7</sub> A<sub>11</sub> A<sub>15</sub> A<sub>18</sub>
+
+A<sub>2</sub> A<sub>6</sub> A<sub>10</sub> A<sub>14</sub> A<sub>17</sub>
+
+A<sub>1</sub> A<sub>5</sub> A<sub>9</sub> A<sub>13</sub> A<sub>16</sub>
+
+B<sub>0</sub> B<sub>4</sub> B<sub>8</sub> B<sub>12</sub>
+
+A<sub>0</sub> A<sub>4</sub> A<sub>8</sub> A<sub>12</sub>
+
+A<sub>0</sub> is assigned to the MSB of the first RS symbol in the FEC frame
+
+Time →
+
+Non-sync trellis group
+
+QAM symbols
+
+T<sub>0</sub> T<sub>1</sub> T<sub>2</sub> T<sub>3</sub> T<sub>4</sub>
+
+B<sub>3</sub> B<sub>7</sub> B<sub>11</sub> B<sub>15</sub> B<sub>18</sub>
+
+B<sub>2</sub> B<sub>6</sub> B<sub>10</sub> B<sub>14</sub> B<sub>17</sub>
+
+B<sub>1</sub> B<sub>5</sub> B<sub>9</sub> B<sub>13</sub> B<sub>16</sub>
+
+A<sub>3</sub> A<sub>7</sub> A<sub>11</sub> A<sub>15</sub> A<sub>18</sub>
+
+A<sub>2</sub> A<sub>6</sub> A<sub>10</sub> A<sub>14</sub> A<sub>17</sub>
+
+A<sub>1</sub> A<sub>5</sub> A<sub>9</sub> A<sub>13</sub> A<sub>16</sub>
+
+S<sub>1</sub> S<sub>3</sub> S<sub>5</sub> S<sub>7</sub>
+
+S<sub>0</sub> S<sub>2</sub> S<sub>4</sub> S<sub>6</sub>
+
+Sync bits
+
+Sync trellis group
+
+38 bits
+
+A<sub>0</sub> B<sub>0</sub> A<sub>1</sub> A<sub>2</sub> A<sub>3</sub> B<sub>1</sub> B<sub>2</sub> B<sub>3</sub> A<sub>4</sub> B<sub>4</sub> A<sub>5</sub> A<sub>6</sub> A<sub>7</sub> B<sub>5</sub> B<sub>6</sub> B<sub>7</sub> A<sub>8</sub> B<sub>8</sub> A<sub>9</sub> A<sub>10</sub> A<sub>11</sub> B<sub>9</sub> B<sub>10</sub> B<sub>11</sub> A<sub>12</sub> B<sub>12</sub> A<sub>13</sub> A<sub>14</sub> A<sub>15</sub> B<sub>13</sub> B<sub>14</sub> B<sub>15</sub> A<sub>16</sub> A<sub>17</sub> A<sub>18</sub> B<sub>16</sub> B<sub>17</sub> B<sub>18</sub>
+
+Non-sync trellis group bit order
+
+S<sub>0</sub> S<sub>1</sub> A<sub>1</sub> A<sub>2</sub> A<sub>3</sub> B<sub>1</sub> B<sub>2</sub> B<sub>3</sub> S<sub>2</sub> S<sub>3</sub> A<sub>5</sub> A<sub>6</sub> A<sub>7</sub> B<sub>5</sub> B<sub>6</sub> B<sub>7</sub> S<sub>4</sub> S<sub>5</sub> A<sub>9</sub> A<sub>10</sub> A<sub>11</sub> B<sub>9</sub> B<sub>10</sub> B<sub>11</sub> S<sub>6</sub> S<sub>7</sub> A<sub>13</sub> A<sub>14</sub> A<sub>15</sub> B<sub>13</sub> B<sub>14</sub> B<sub>15</sub> A<sub>16</sub> A<sub>17</sub> A<sub>18</sub> B<sub>16</sub> B<sub>17</sub> B<sub>18</sub>
+
+Sync trellis group bit order
+
+T0903540-96/d23
+
+Figure B.15: 256-QAM sync and non-sync trellis groups. The diagram shows two trellis group structures. The 'Non-sync trellis group' is a 5x8 grid of QAM symbols with columns T0 to T4 and rows containing symbols like B3, B7, B11, B15, B18. The 'Sync trellis group' is similar but includes 'Sync bits' S0, S1, S2, S3, S4, S5, S6, S7 in the bottom two rows. Below the grids, two horizontal bit sequences are shown: 'Non-sync trellis group bit order' (A0, B0, A1, A2, A3, B1, B2, B3, A4, B4, A5, A6, A7, B5, B6, B7, A8, B8, A9, A10, A11, B9, B10, B11, A12, B12, A13, A14, A15, B13, B14, B15, A16, A17, A18, B16, B17, B18) and 'Sync trellis group bit order' (S0, S1, A1, A2, A3, B1, B2, B3, S2, S3, A5, A6, A7, B5, B6, B7, S4, S5, A9, A10, A11, B9, B10, B11, S6, S7, A13, A14, A15, B13, B14, B15, A16, A17, A18, B16, B17, B18). A note states 'A0 is assigned to the MSB of the first RS symbol in the FEC frame'. A 'Time' arrow points right, and a '38 bits' scale bar is shown.
+
+**Figure B.15 – 256-QAM sync and non-sync trellis groups**
+
+To form trellis groups from RS code words, the RS code words are serialized beginning with the MSB of the first symbol of the first RS code word following the frame sync trailer. Bits are placed into trellis group locations from RS symbols in the order: A<sub>0</sub> B<sub>0</sub> A<sub>1</sub> ... B<sub>3</sub> A<sub>4</sub> B<sub>4</sub> ... B<sub>16</sub> B<sub>17</sub> B<sub>18</sub> as shown in Figure B.15. For sync trellis groups, the bits from serialized RS symbols are placed beginning at location A<sub>1</sub> instead of A<sub>0</sub>. The last five trellis groups in an FEC frame each contain 8 of the 40 sync bits, S<sub>0</sub> S<sub>1</sub> ... S<sub>7</sub> in the frame sync trailer shown in Figure B.10.
+
+Of the 38 input bits that form a trellis group, each of two groups of 4 bits of type differentially pre-coded bit streams in a trellis group are separately encoded by a Binary Convolutional Coder (BCC). Each BCC produces 5 coded bits, as shown in Figure B.14. The remaining bits are sent to the QAM mapper uncoded. This produces a total output of 40 bits per trellis group. Thus, the overall code rate for 256-QAM trellis coded modulation is 19/20.
+
+##### B.5.5.3 Rotationally invariant pre-coding
+
+The differential pre-coder shown in Figure B.16 performs the 90° rotationally invariant trellis coding. Rotationally invariant coding is employed for both 64- and 256-QAM modulation. The key for robust modem design is to have very fast recovery from carrier phase slips. Non-rotationally
+
+invariant coding requires resynchronization of the FEC when the carrier phase tracking changes quadrant alignment, leading to a burst of errors at the FEC output.
+
+The differential pre-coder allows the information to be carried by the change in phase, rather than by the absolute phase. For 64-QAM, the 3rd and the 6th bits of the 6-bit symbols are differentially encoded, and for 256-QAM, the 4th and 8th bits are differentially encoded. If you mask out the 3rd and the 6th bits in 64-QAM as in Figure B.18 (labelled  $C^3$  and  $C^0$ ) and the 4th and 8th bits in 256-QAM as in Figure B.19 (labelled  $C^4$  and  $C^0$ ), the  $90^\circ$  rotational invariance of the remaining bits is inherent in the labelling of the symbol constellation.
+
+![Diagram of a Differential pre-coder block with inputs W_j and Z_j, and outputs x_j and Y_j. Below the block, the differential pre-coder equations are shown in a box.](dcb5711d118ae6753b0e12f86eda37db_img.jpg)
+
+Differential pre-coder equations
+
+$$\begin{aligned} x_j &= W_j + x_{j-1} + Z_j(x_{j-1} + Y_{j-1}) \\ Y_j &= Z_j + W_j + Y_{j-1} + Z_j(x_{j-1} + Y_{j-1}) \end{aligned}$$
+
+T0903550-96/d24
+
+Diagram of a Differential pre-coder block with inputs W\_j and Z\_j, and outputs x\_j and Y\_j. Below the block, the differential pre-coder equations are shown in a box.
+
+**Figure B.16 – Differential pre-coder**
+
+##### B.5.5.4 Binary Convolutional Coder
+
+The trellis coded modulator includes a punctured rate 1/2 binary convolutional encoder that is used to introduce the redundancy into the LSBs of the trellis group. The convolutional encoder is a 16-state non-systematic rate 1/2 encoder with the generator:  $G1 = 010\ 101$ ,  $G2 = 011\ 111$  (25,37<sub>octal</sub>), or equivalently the generator matrix  $[1 \oplus D^2 \oplus D^4, 1 \oplus D \oplus D^2 \oplus D^3 \oplus D^4]$ . At the beginning of a trellis group, the BCC commutator is initially in the G1 position. For each input bit presented to the tapped delay line, two bits (G1, followed by G2) are subsequently produced at the output in accordance with the associated set of generator coefficients. For each trellis group, 4 input bits produce 8 convolutionally encoded bits. This time output of the encoder is selected according to a puncture matrix:  $[P1, P2] = [0001; 1111]$  ("0" denotes NO transmission, "1" denotes transmission), which produces a single serial bit stream. The puncture matrix essentially converts the rate 1/2 encoder to rate 4/5, since only 5 of the 8 encoded bits are retained after puncturing. The internal structure of the punctured encoder is illustrated in Figure B.17.
+
+![Diagram of a (1/2) Binary Convolutional Coder. The input enters from the left, labeled 'from pre-coder'. It splits into two parallel paths. The top path is labeled 'G1 = 25(octal)' and the bottom path is labeled 'G2 = 37(octal)'. Both paths pass through a series of four delay elements labeled 'Z^-1'. The output of the top path is XORed with the output of the bottom path at a node labeled '+'. The resulting 5-bit sequential output is then passed to a commutator. The commutator is controlled by a 'Puncture matrix' which has the values '0 0 0 1' for the top path and '1 1 1 1' for the bottom path. The output of the commutator is labeled 'To QAM mapper'. A text box below the diagram states: 'For every 4-bit sequential input yields a 5-bit sequential output'. A reference code 'T0903560-96/d25' is also present.](11edb7fcedf09ac6a817f8d7b8c61eec_img.jpg)
+
+(1/2) Binary Convolutional Coder
+
+```
+
+graph LR
+    In[from pre-coder] --> Split(( ))
+    Split --> G1_1[1]
+    Split --> G2_1[1]
+    
+    G1_1 --> Z1[Z^-1]
+    Z1 --> Z2[Z^-1]
+    Z2 --> Z3[Z^-1]
+    Z3 --> Z4[Z^-1]
+    
+    G1_1 --> XOR1((+))
+    Z2 --> XOR1
+    Z4 --> XOR1
+    
+    G2_1 --> XOR2((+))
+    Z1 --> XOR2
+    Z2 --> XOR2
+    Z3 --> XOR2
+    Z4 --> XOR2
+    
+    XOR1 --> Commutator
+    XOR2 --> Commutator
+    Commutator --> Out[To QAM mapper]
+    
+    subgraph Puncture_Matrix
+    PM1[0 0 0 1]
+    PM2[1 1 1 1]
+    end
+
+```
+
+For every 4-bit sequential input  
+yields a 5-bit sequential output
+
+Binary Convolutional Coder Structure
+
+- 1) 16 state.
+- 2) Rate 1/2 binary convolutional coder.
+- 3) Generating code:  $G1 = [010101]$ ,  $G2 = [011111]$  ( $25, 37_{octal}$ )  
+or Generating Matrix of  $[1(+)D^2(+)D^4, 1(+)D(+)D^2(+)D^3(+)D^4]$   
+where  $D$  is equal to  $Z^{-1}$ .
+- 4) Punctured matrix  $[P1;P2] = [0001;1111]$ .
+
+NOTE 1 – 0 denotes NO transmission  
+1 denotes transmission.
+
+NOTE 2 – (+) denotes XOR operation.
+
+T0903560-96/d25
+
+Diagram of a (1/2) Binary Convolutional Coder. The input enters from the left, labeled 'from pre-coder'. It splits into two parallel paths. The top path is labeled 'G1 = 25(octal)' and the bottom path is labeled 'G2 = 37(octal)'. Both paths pass through a series of four delay elements labeled 'Z^-1'. The output of the top path is XORed with the output of the bottom path at a node labeled '+'. The resulting 5-bit sequential output is then passed to a commutator. The commutator is controlled by a 'Puncture matrix' which has the values '0 0 0 1' for the top path and '1 1 1 1' for the bottom path. The output of the commutator is labeled 'To QAM mapper'. A text box below the diagram states: 'For every 4-bit sequential input yields a 5-bit sequential output'. A reference code 'T0903560-96/d25' is also present.
+
+**Figure B.17 – Punctured Binary Convolutional Coder**
+
+##### B.5.5.5 QAM constellation mapping
+
+For 64-QAM, the QAM mapper receives the coded and uncoded 3-bit 'A' and 'B' data from the trellis coded modulator. It uses these bits to address a look-up table which produces the 6-bit constellation symbol. The 6-bit constellation symbol is then sent to the 64-QAM modulator where the signal constellation illustrated in Figure B.18 is generated.
+
+For 256-QAM, the QAM mapper receives the coded and uncoded 4-bit 'A' and 'B' data from the trellis coded modulator. It uses these bits to address a look-up table which produces the 8-bit constellation symbol. The 8-bit constellation symbol is then sent to the 256-QAM modulator where the signal constellation illustrated in Figure B.19 is generated.
+
+![64-QAM constellation diagram showing a grid of 64 points with binary labels. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'. A callout box indicates the bit mapping: C5 C4 C3, C2 C1 C0.](bafe3665fa89ba09857af5a2532c79fe_img.jpg)
+
+The figure shows a 64-QAM constellation diagram. It consists of an 8x8 grid of points. Each point is labeled with a 12-bit binary string, which is a concatenation of two 6-bit strings. The horizontal axis is labeled 'I' (In-phase) and the vertical axis is labeled 'Q' (Quadrature). A callout box in the top right corner indicates the bit mapping:  $C^5 C^4 C^3, C^2 C^1 C^0$ .
+
+|         |         |         |         |         |         |         |         |
+|---------|---------|---------|---------|---------|---------|---------|---------|
+| 110,111 | 111,011 | 010,111 | 011,011 | 100,101 | 101,111 | 110,101 | 111,111 |
+| 110,100 | 111,000 | 010,100 | 011,000 | 100,000 | 101,010 | 110,000 | 111,010 |
+| 100,111 | 101,011 | 000,111 | 001,011 | 000,101 | 001,111 | 010,101 | 011,111 |
+| 100,100 | 101,000 | 000,100 | 001,000 | 000,000 | 001,010 | 010,000 | 011,010 |
+| 010,011 | 011,001 | 000,011 | 001,001 | 000,001 | 001,101 | 100,001 | 101,101 |
+| 010,110 | 011,100 | 000,110 | 001,100 | 000,010 | 001,110 | 100,010 | 101,110 |
+| 110,011 | 111,001 | 100,011 | 101,001 | 010,001 | 011,101 | 110,001 | 111,101 |
+| 110,110 | 111,100 | 100,110 | 101,100 | 010,010 | 011,110 | 110,010 | 111,110 |
+
+64-QAM constellation diagram showing a grid of 64 points with binary labels. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'. A callout box indicates the bit mapping: C5 C4 C3, C2 C1 C0.
+
+T0903570-96/d26
+
+**Figure B.18 – 64-QAM constellation**
+
+![256-QAM constellation diagram showing a grid of 16x16 points. Each point is labeled with two 4-bit binary sequences. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'. A legend in the top right corner shows the mapping: C7C6C5C4 to C3C2C1C0. The diagram is centered at the origin with arrows pointing outwards along the I and Q axes.](48a08e5cabec8b75386679d8a57dec3e_img.jpg)
+
+256-QAM constellation diagram showing a grid of 16x16 points. Each point is labeled with two 4-bit binary sequences. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'. A legend in the top right corner shows the mapping: C7C6C5C4 to C3C2C1C0. The diagram is centered at the origin with arrows pointing outwards along the I and Q axes.
+
+T0903580-96/d27
+
+Figure B.19 – 256-QAM constellation
+
+## B.6 Modulation and demodulation
+
+#### B.6.1 QAM characteristics
+
+The cable transmission format is summarized in Table B.3 for 64-QAM and 256-QAM. Table B.4 contains a summary of the pertinent characteristics of the variable interleaving modes.
+
+**Table B.3 – Cable transmission format**
+
+| Parameter                 | 64-QAM format                                              | 256-QAM format                                             |
+|---------------------------|------------------------------------------------------------|------------------------------------------------------------|
+| Modulation                | 64-QAM, rotationally invariant coding                      | 256-QAM, rotationally invariant coding                     |
+| Symbol size               | 3 bits for "I" and 3 bits for "Q" dimensions               | 4 bits for "I" and 4 bits for "Q" dimensions               |
+| Transmission band         | 54 to 860 MHz (Note)                                       | 54 to 860 MHz (Note)                                       |
+| Channel spacing           | 6 MHz (Note)                                               | 6 MHz (Note)                                               |
+| Symbol rate               | 5.056941 Msps $\pm$ 5 ppm (Note)                           | 5.360537 Msps $\pm$ 5 ppm (Note)                           |
+| Information bit rate      | 26.97035 Mbps $\pm$ 5 ppm (Note)                           | 38.81070 Mbps $\pm$ 5 ppm (Note)                           |
+| Frequency response        | Square root raised cosine filter (Roll-off $\approx$ 0.18) | Square root raised cosine filter (Roll-off $\approx$ 0.12) |
+| FEC framing               | 42-bit sync trailer following 60 RS blocks (see B.5.3)     | 40-bit sync trailer following 88 RS blocks (see B.5.3)     |
+| QAM constellation mapping | 6 bits per symbol (see B.5.5)                              | 8 bits per symbol (see B.5.5)                              |
+
+NOTE – These values are specific to 6 MHz channel spacing. Additional sets of values for differing channel spacing are under study.
+
+**Table B.4 – Variable interleaving modes**
+
+|              | Level 1                                         | Level 2                                                                           |
+|--------------|-------------------------------------------------|-----------------------------------------------------------------------------------|
+| QAM format   | 64-QAM (see Table B.3)                          | 64- or 256-QAM (see Table B.3)                                                    |
+| Interleaving | Fixed interleaving (see B.5.2)<br>I = 128 J = 1 | Variable interleaving (see B.5.2)<br>I = 128,64,32,16,8<br>J = 1,2,3,4,5,6,7,8,16 |
+
+#### B.6.2 QAM modulator RF output
+
+The RF modulated QAM signal  $s(t)$  is given by:
+
+$$s(t) = I(t) \times \cos(2\pi ft) + Q(t) \times \sin(2\pi ft)$$
+
+where  $t$  denotes time,  $f$  denotes RF carrier frequency and where  $I(t)$  and  $Q(t)$  are the respective Root-Nyquist filtered baseband quadrature components of the constellation symbols.
+
+# Annex C
+
+## Digital multi-programme System C
+
+(This annex forms an integral part of this Recommendation)
+
+## C.1 Introduction
+
+This annex describes the framing structure, channel coding and modulation of digital multi-programme system for cable distribution.
+
+The system employs the transport multiplexing based on MPEG-2 (see Reference [2]), guaranteeing interoperability with other media such as digital broadcasting, ISDN networks or packaged media. The framing structure and the channel coding are the same as in Annex A. The modulation schemes are 64-QAM and 256-QAM, and the QAM symbol rate and the roll-off factor are optimized for the 6 MHz channel plan.
+
+The system also allows for further evolution to higher order QAM constellations, and the appropriate modifications to its channel coding and symbol mapping are currently under study.
+
+## C.2 Cable system concept
+
+The cable system shall be defined as the functional block of equipment performing the adaptation of the baseband TV signals to the cable channel characteristics.
+
+In the cable head-end, the TV baseband signal may come from broadcasting, second distribution links, contribution links and local programme sources.
+
+The following process shall be applied as shown in Figure C.1.
+
+#### C.2.1 Baseband interfacing and sync
+
+This unit shall adapt the data structure to the format of the signal source. The framing structure shall be in accordance with MPEG-2 transport layer including sync bytes.
+
+#### C.2.2 Sync 1 inversion and randomization
+
+This unit shall invert the MPEG-2 Sync byte (Sync 1) every eight packets, according to the MPEG-2 framing structure, and shall randomize the data stream for spectrum shaping purposes.
+
+#### C.2.3 Reed-Solomon (RS) coder
+
+This unit shall apply a shortened Reed-Solomon (RS) code to each randomized transport packet to generate an error-protected packet. This code shall also be applied to the Sync byte itself.
+
+#### C.2.4 Convolutional interleaver
+
+This unit shall perform a depth  $I = 12$  convolutional interleaving of the error-protected packets. The periodicity of the sync bytes shall remain unchanged.
+
+#### C.2.5 Byte to m-tuple conversion
+
+This unit shall perform a conversion of the bytes generated by the interleaver into QAM symbols.
+
+#### C.2.6 Differential encoding
+
+In order to get a rotation-invariant constellation, this unit shall apply a differential encoding of the two Most Significant Bits (MSBs) of each symbol.
+
+#### C.2.7 QAM modulation and physical interface
+
+This unit performs a square-root raised cosine filtering of the I and Q signals prior to QAM modulation. This is followed by interfacing the QAM modulated signal to the Radio Frequency (RF) cable channel.
+
+![Figure C.1 – System configuration block diagram showing the signal flow from Data input through various processing stages to the RF Cable Channel and then back through demodulation stages to the Data output.](dcc2d5a5b39f780e7a224bb01ba1ef6e_img.jpg)
+
+The diagram illustrates the system configuration for QAM modulation and physical interface. It is divided into two main parts: the transmitter (top) and the receiver (bottom), connected by an RF Cable Channel.
+
+**Transmitter (Top):** The signal flow starts with **Data** entering a block labeled **Sync1 Inversion and Randomization**. The output is an 8-bit bus, which then enters a **Reed-Solomon Coder (204,188)**. The output is another 8-bit bus, followed by a **Convol. Interleaver I = 12 bytes**. The output is an 8-bit bus, then a **Byte to m-tuple conversion** block. The output is an m-bit bus, followed by a **Differential encoding** block. The output is an m-bit bus, which then enters the **QAM Modulator and RF Physical Interface**. The output of this block is connected to the **RF Cable Channel**.
+
+**Receiver (Bottom):** The signal flow starts from the **RF Cable Channel** entering a block labeled **RF Physical interface and QAM Demodulator**. The output is an m-bit bus, which then enters a **Matched filter and Equalizer**. The output is an m-bit bus, followed by a **Differential decoder**. The output is an m-bit bus, then a **Symbol to byte mapping** block. The output is an 8-bit bus, followed by a **Convolutional deinterleaver**. The output is an 8-bit bus, then a **Reed-Solomon decoder**. The output is an 8-bit bus, which then enters a **Sync1 Inversion and Derandomization** block. The final output is **Data**.
+
+A label **J.83(07)\_FC.1** is present at the bottom right of the diagram.
+
+Figure C.1 – System configuration block diagram showing the signal flow from Data input through various processing stages to the RF Cable Channel and then back through demodulation stages to the Data output.
+
+Figure C.1 – System configuration
+
+#### C.2.8 Cable receiver
+
+A System receiver shall perform the inverse signal processing, as described for the modulation process above, in order to recover the baseband signal.
+
+In addition, each cable receiver should install an equalizer to prevent increase of the bit-error caused by the reflection in the cable system.
+
+## C.3 MPEG-2 transport layer
+
+The transport layer for the digital multi-programme system is based on MPEG-2 (see Reference [2]). The transport multiplexing is performed in Transport Stream-Packet having 188 bytes, in conformance with MPEG-2.
+
+## C.4 Framing structure
+
+The framing organization shall be based on the MPEG-2 transport packet structure. The System framing structure is shown in Figure C.2.
+
+![Figure C.2 – Transmission signal configuration. This diagram illustrates the structure of an MPEG-2 transport stream across several processing stages. At the top, a horizontal double-headed arrow indicates a sequence of '8 packets'. Below this, the 'MPEG-2 TS packet' is shown as a box containing 'Sync byte' and '187 bytes', with '47 HEX' written below the sync byte. The 'MPEG-2 transport stream (sync inverted)' shows a sequence of packets: 'Sync 1', '187 bytes', 'Sync 2', '187 bytes', 'Sync 8', '187 bytes', and 'Sync 1'. Below this sequence, 'B8 HEX (inverted)' is at the start and end, and '47 HEX' is shown below the second and third sync bytes. A central section labeled '1503 bytes' contains a 'Pseudo-random signal from 1 + x^14 + x^15 (initialization signal 100101010000000) is appended. (No sync byte dispersed)'. The 'Energy dispersal' stage is shown as a sequence of boxes with grey shaded areas. Below this, the stream is shown again with 'Sync 1', 'Randomized 187 bytes', 'Sync 2', 'Randomized 187 bytes', 'Sync 8', 'Randomized 187 bytes', and 'Sync 1'. Below this, 'B8 HEX (inverted)' is at the start and end, and '47 HEX' is shown below the second and third sync bytes. The 'Error correction' stage shows a box with 'Sync byte', 'Randomized 187 bytes', and 'RS (204,188)', with '47 HEX or B8 HEX' written below. The final stage shows a sequence of 'Sync byte', '203 bytes', 'Sync byte', and '203 bytes', with '47 HEX or B8 HEX' written below each sync byte. The diagram is labeled 'T0903080-95/d29' at the bottom right.](e451401f8fa77b466f401d5fce15b26c_img.jpg)
+
+Figure C.2 – Transmission signal configuration. This diagram illustrates the structure of an MPEG-2 transport stream across several processing stages. At the top, a horizontal double-headed arrow indicates a sequence of '8 packets'. Below this, the 'MPEG-2 TS packet' is shown as a box containing 'Sync byte' and '187 bytes', with '47 HEX' written below the sync byte. The 'MPEG-2 transport stream (sync inverted)' shows a sequence of packets: 'Sync 1', '187 bytes', 'Sync 2', '187 bytes', 'Sync 8', '187 bytes', and 'Sync 1'. Below this sequence, 'B8 HEX (inverted)' is at the start and end, and '47 HEX' is shown below the second and third sync bytes. A central section labeled '1503 bytes' contains a 'Pseudo-random signal from 1 + x^14 + x^15 (initialization signal 100101010000000) is appended. (No sync byte dispersed)'. The 'Energy dispersal' stage is shown as a sequence of boxes with grey shaded areas. Below this, the stream is shown again with 'Sync 1', 'Randomized 187 bytes', 'Sync 2', 'Randomized 187 bytes', 'Sync 8', 'Randomized 187 bytes', and 'Sync 1'. Below this, 'B8 HEX (inverted)' is at the start and end, and '47 HEX' is shown below the second and third sync bytes. The 'Error correction' stage shows a box with 'Sync byte', 'Randomized 187 bytes', and 'RS (204,188)', with '47 HEX or B8 HEX' written below. The final stage shows a sequence of 'Sync byte', '203 bytes', 'Sync byte', and '203 bytes', with '47 HEX or B8 HEX' written below each sync byte. The diagram is labeled 'T0903080-95/d29' at the bottom right.
+
+Interleaving: Convolutional interleaving (by byte unit).  
+No delay in sync byte.
+
+**Figure C.2 – Transmission signal configuration**
+
+## C.5 Channel coding
+
+To achieve the appropriate level of error protection required for cable transmission of digital data, a Forward Error Correction (FEC) based on Reed-Solomon encoding shall be used. Protection against burst errors shall be achieved by the use of interleaving.
+
+#### C.5.1 Randomization
+
+The System input stream shall be organized in fixed length packets (see Figure C.2), following the MPEG-2 transport multiplexer. The total packet length of the MPEG-2 transport multiplex packet is 188 bytes. This includes one sync-word byte.
+
+In order to offer maximum compatibility with other media and to ensure adequate binary transitions for clock recovery, the data at the output of the MPEG-2 transport multiplex shall be randomized in accordance with the configuration shown in Figure C.3.
+
+The polynomial for the Pseudo-Random Binary Sequence (PRBS) generator shall be:
+
+$$x^{15} + x^{14} + 1$$
+
+Loading of the sequence "100101010000000" into the PRBS registers, as indicated in Figure C.3, shall be initiated at the start of every eight transport packets. To provide an initialization signal for the descrambler, the MPEG-2 sync byte of the first transport packet in a group of eight packets shall be bit wise inverted from 47<sub>HEX</sub> to B8<sub>HEX</sub>.
+
+The first bit at the output of the PRBS generator shall be applied to the first bit of the first byte following the inverted MPEG-2 sync byte (i.e., B8<sub>HEX</sub>). To aid other synchronization functions, during the MPEG-2 sync bytes of the subsequent seven transport packets, the PRBS generation continues, but its output shall be disabled, leaving these bytes unrandomized. The period of the PRBS sequence shall therefore be 1503 bytes.
+
+![Scrambler/descrambler schematic diagram showing a 15-bit shift register, XOR gates, and an AND gate for scrambling data. The shift register is initialized with the sequence 100101010000000. The diagram includes labels for 'Initialization sequence', 'Enable', 'Clear/randomized data input', and 'Randomized/de-randomized data output'. A sample data input and PRBS sequence are shown at the bottom left.](08c7a76a7786bd08b99dd4cb41583ef4_img.jpg)
+
+Initialization sequence
+
+1 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0
+
+1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
+
+0 0 0 0 0 0 1 1 ....
+
+XOR
+
+AND
+
+Enable
+
+Clear/randomized data input
+
+XOR
+
+Randomized/de-randomized data output
+
+T0904330-97/d30
+
+Data input (MSB first): 1 0 1 | 1 1 0 0 0    x x x | x x x x x .... |  
+PRBS sequence:                            |            0 0 0 | 0 0 0 1 1 .... |
+
+Scrambler/descrambler schematic diagram showing a 15-bit shift register, XOR gates, and an AND gate for scrambling data. The shift register is initialized with the sequence 100101010000000. The diagram includes labels for 'Initialization sequence', 'Enable', 'Clear/randomized data input', and 'Randomized/de-randomized data output'. A sample data input and PRBS sequence are shown at the bottom left.
+
+Figure C.3 – Scrambler/descrambler schematic diagram
+
+#### C.5.2 Reed-Solomon coding
+
+The shortened Reed-Solomon (204, 188) code shall be used for the forward error correction. The Reed-Solomon coding can be organized by appending "0" of 51 bytes before the input data byte and deleting it after the coding at the general purpose of Reed-Solomon (255, 239) coding circuit.
+
+Code Generator Polynomial:
+
+$$g(x) = (x + \lambda^0)(x + \lambda^1)(x + \lambda^2) \cdots (x + \lambda^{15})$$
+
+where:
+
+$$\lambda = 02_{\text{HEX}}$$
+
+Field Generator Polynomial:
+
+$$p(x) = x^8 + x^4 + x^3 + x^2 + 1$$
+
+#### C.5.3 Convolutional interleaving
+
+Following the scheme of Figure C.4, convolutional interleaving with depth  $I = 12$  shall be applied to the error-protected packets.
+
+The interleaver may be composed of  $I = 12$  branches, cyclically connected to the input byte-stream by the input switch. Each branch shall be a First In First Out (FIFO) shift register, with depth ( $M_j$ ) cells (where  $M = 17 = N/I$ ,  $N = 204 =$  error-protected frame length,  $I = 12 =$  interleaving depth,  $j =$  branch index). The cells of the FIFO shall contain one byte, and the input and output switches shall be synchronized.
+
+For synchronization purposes, the sync bytes and the inverted sync bytes shall be always routed in the branch "0" of the interleaver (corresponding to a null delay).
+
+NOTE – The de-interleaver is similar, in principle, to the interleaver, but the branch indexes are reversed (i.e.,  $j = 0$  corresponds to the largest delay). The de-interleaver synchronization can be carried out by routing the first recognized sync byte in the "0" branch.
+
+### C.6 Modulation
+
+#### C.6.1 Byte to symbol mapping
+
+After convolutional interleaving, an exact mapping of bytes into symbols shall be performed. The mapping shall rely upon the use of byte boundaries in the modulation system.
+
+In each case, the MSB of symbol  $Z$  shall be taken from the MSB of byte  $V$ . Correspondingly, the next significant bit of the symbol shall be taken from the next significant bit of the byte. For the case of  $2^m$ -QAM modulation, the process shall map  $k$  bytes into  $n$  symbols, such that:
+
+$$8k = n \cdot m$$
+
+The process is illustrated for the case of 64-QAM (when  $m = 6$ ,  $k = 3$  and  $n = 4$ ) and 256-QAM (when  $m = 8$ ,  $k = 3$  and  $n = 3$ ) in Figure C.5.
+
+#### C.6.2 Differential encoding
+
+The two MSBs of each symbol shall then be differentially coded in order to obtain a  $\pi/2$  rotation-invariant QAM constellation. The differential encoding of the two MSBs shall be given by the following expression:
+
+$$\begin{aligned} I_k &= \overline{(A_k \oplus B_k)} \cdot (A_k \oplus I_{k-1}) + (A_k \oplus B_k) \cdot (A_k \oplus Q_{k-1}) \\ Q_k &= \overline{(A_k \oplus B_k)} \cdot (B_k \oplus Q_{k-1}) + (A_k \oplus B_k) \cdot (B_k \oplus I_{k-1}) \end{aligned}$$
+
+Figure C.6 gives an example of implementation of byte to symbol conversion for 64-QAM and 256-QAM.
+
+#### C.6.3 QAM constellation
+
+The system can be adapted to 6 MHz channel spacing. The byte to modulation scheme described in this subclause is directly related to the byte to symbol mapping method given in C.6.1.
+
+The modulation of the system shall be Quadrature Amplitude Modulation (QAM) with 64 points (64-QAM) and 256 points (256-QAM) in the constellation chart.
+
+The System constellation charts for 64-QAM and 256-QAM are given in Figure C.7.
+
+![Diagram showing the interleaving of 204 (12 x 17) bytes. It illustrates the mapping of bytes from an input stream to an output stream, with specific delays for different byte positions. The input stream has a 12-byte sync word. The output stream shows the interleaved data with delays: 12 x 17 x 3 - 1 bytes, 12 x 17 x 2 - 1 bytes, 12 x 17 x 1 - 1 bytes, and 12 x 17 x 1 - 1 bytes. A legend indicates that a grey box represents an MPEG sync byte.](77959075c823bb5169480d7b8ff82a63_img.jpg)
+
+204  $(12 \times 17)$  bytes
+
+12 bytes
+
+$12 \times 17 \times 3 - 1$  bytes delay
+
+$12 \times 17 \times 2 - 1$  bytes delay
+
+$12 \times 17 \times 1 - 1$  bytes delay
+
+$12 \times 17 \times 1 - 1$  bytes delay
+
+MPEG sync byte
+
+Diagram showing the interleaving of 204 (12 x 17) bytes. It illustrates the mapping of bytes from an input stream to an output stream, with specific delays for different byte positions. The input stream has a 12-byte sync word. The output stream shows the interleaved data with delays: 12 x 17 x 3 - 1 bytes, 12 x 17 x 2 - 1 bytes, 12 x 17 x 1 - 1 bytes, and 12 x 17 x 1 - 1 bytes. A legend indicates that a grey box represents an MPEG sync byte.
+
+|                          |                         |                                                                                                                                                                                                                                                                                                            |
+|--------------------------|-------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Interleaving depth       | $I (= 12)$              | <p>Image: Diagram illustrating the required memory capacity for interleaving. It shows a triangular memory structure with a height of I and a base of L (17 x 11). Arrows indicate the flow of data into and out of the memory structure.</p> <p><math>I</math></p> <p><math>L (= 17 \times 11)</math></p> |
+| Synchronization          | Routing SW (Cycle $I$ ) |                                                                                                                                                                                                                                                                                                            |
+| Required memory capacity | $1/2 \times I \times L$ |                                                                                                                                                                                                                                                                                                            |
+
+![Diagram showing the sync word route for an interleaver and a de-interleaver. The interleaver (I = 12) shows 12 sync word routes, each with a delay of 17 x n bytes. The de-interleaver (I = 12) shows the reverse process.](47a7beddcb8a1b7abdca746967e32bb4_img.jpg)
+
+Sync word route
+
+0
+
+1  $17 \times 1$
+
+2  $17 \times 2$
+
+3  $17 \times 3$
+
+11 =  $I - 1$   $17 \times 11$
+
+1 byte per each position
+
+FIFO shift register
+
+Interleaver  $I = 12$
+
+Sync word route
+
+0  $17 \times 11$
+
+8  $17 \times 3$
+
+9  $17 \times 2$
+
+10  $17 \times 1$
+
+11 =  $I - 1$
+
+1 byte per each position
+
+De-interleaver  $I = 12$
+
+Diagram showing the sync word route for an interleaver and a de-interleaver. The interleaver (I = 12) shows 12 sync word routes, each with a delay of 17 x n bytes. The de-interleaver (I = 12) shows the reverse process.
+
+T0903100-95/d31
+
+**Figure C.4 – Interleaving configuration**
+
+
+
+![Block diagram for 64-QAM Byte to symbol conversion. A byte with bits b0 through b5 is input. Bits b0, b1, b2, and b3 are direct inputs to a 'Mapping' block. Bit b4 (labeled Bk = b4) and the most significant bit b5 (labeled Ak = b5 MSB) are inputs to a 'Differential encoding' block. The 'Differential encoding' block outputs Qk and Ik, which are then inputs to the 'Mapping' block. The 'Mapping' block produces two outputs, I and Q. The title '64-QAM Byte to symbol conversion' is centered below the diagram.](9a5927586a691c4908aa2cf98bd47ebb_img.jpg)
+
+**64-QAM Byte to symbol conversion**
+
+Block diagram for 64-QAM Byte to symbol conversion. A byte with bits b0 through b5 is input. Bits b0, b1, b2, and b3 are direct inputs to a 'Mapping' block. Bit b4 (labeled Bk = b4) and the most significant bit b5 (labeled Ak = b5 MSB) are inputs to a 'Differential encoding' block. The 'Differential encoding' block outputs Qk and Ik, which are then inputs to the 'Mapping' block. The 'Mapping' block produces two outputs, I and Q. The title '64-QAM Byte to symbol conversion' is centered below the diagram.
+
+![Block diagram for 256-QAM Byte to symbol conversion. A byte with bits b0 through b7 is input. Bits b0, b1, b2, b3, b4, and b5 are direct inputs to a 'Mapping' block. Bit b6 (labeled Bk = b6) and the most significant bit b7 (labeled Ak = b7 MSB) are inputs to a 'Differential encoding' block. The 'Differential encoding' block outputs Qk and Ik, which are then inputs to the 'Mapping' block. The 'Mapping' block produces two outputs, I and Q. The title '256-QAM Byte to symbol conversion' is centered below the diagram. A small label 'J.83(07)_FC.6' is in the bottom right corner.](70a863dc6cd47bac82c12162a9479aac_img.jpg)
+
+**256-QAM Byte to symbol conversion**
+
+J.83(07)\_FC.6
+
+Block diagram for 256-QAM Byte to symbol conversion. A byte with bits b0 through b7 is input. Bits b0, b1, b2, b3, b4, and b5 are direct inputs to a 'Mapping' block. Bit b6 (labeled Bk = b6) and the most significant bit b7 (labeled Ak = b7 MSB) are inputs to a 'Differential encoding' block. The 'Differential encoding' block outputs Qk and Ik, which are then inputs to the 'Mapping' block. The 'Mapping' block produces two outputs, I and Q. The title '256-QAM Byte to symbol conversion' is centered below the diagram. A small label 'J.83(07)\_FC.6' is in the bottom right corner.
+
+**Figure C.6 – Example of implementation of byte to symbol conversion and the differential coding of the two MSBs**
+
+![Constellation chart for 64-QAM showing 64 points arranged in a grid on an I-Q plane. The chart is divided into four quadrants labeled Ik Qk = 10, 00, 11, and 01. Each quadrant contains a 4x4 grid of points, each labeled with a 6-bit binary sequence b5 b4 b3 b2 b1 b0.](103781b498cc6846ffc11a041e14dc3e_img.jpg)
+
+The figure shows a 64-QAM constellation diagram on an  $I$ - $Q$  plane. The horizontal axis is labeled  $I$  and the vertical axis is labeled  $Q$ . The constellation is divided into four quadrants, each containing a  $4 \times 4$  grid of points. Each point is represented by a circle and labeled with a 6-bit binary sequence  $b_5 b_4 b_3 b_2 b_1 b_0$ .
+
+The quadrants are labeled as follows:
+
+- Top-Left:  $I_k Q_k = 10$
+- Top-Right:  $I_k Q_k = 00$
+- Bottom-Left:  $I_k Q_k = 11$
+- Bottom-Right:  $I_k Q_k = 01$
+
+The bit sequences for each quadrant are:
+
+- Top-Left ( $I_k Q_k = 10$ ):**
+  - Row 1: 101100, 101110, 100110, 100100
+  - Row 2: 101101, 101111, 100111, 100101
+  - Row 3: 101001, 101011, 100011, 100001
+  - Row 4: 101000, 101010, 100010, 100000
+- Top-Right ( $I_k Q_k = 00$ ):**
+  - Row 1: 001000, 001001, 001101, 001100
+  - Row 2: 001010, 001011, 001111, 001110
+  - Row 3: 000010, 000011, 000111, 000110
+  - Row 4: 000000, 000001, 000101, 000100
+- Bottom-Left ( $I_k Q_k = 11$ ):**
+  - Row 1: 110100, 110101, 110001, 110000
+  - Row 2: 110110, 110111, 110011, 110010
+  - Row 3: 111110, 111111, 111011, 111010
+  - Row 4: 111100, 111101, 111001, 111000
+- Bottom-Right ( $I_k Q_k = 01$ ):**
+  - Row 1: 010000, 010010, 011010, 011000
+  - Row 2: 010001, 010011, 011011, 011001
+  - Row 3: 010101, 010111, 011111, 011101
+  - Row 4: 010100, 010110, 011110, 011100
+
+T0903130-95/d34
+
+Constellation chart for 64-QAM showing 64 points arranged in a grid on an I-Q plane. The chart is divided into four quadrants labeled Ik Qk = 10, 00, 11, and 01. Each quadrant contains a 4x4 grid of points, each labeled with a 6-bit binary sequence b5 b4 b3 b2 b1 b0.
+
+**Figure C.7 – Part 1: Constellation chart for 64-QAM**
+
+![Constellation chart for 256-QAM showing 256 points in a grid across four quadrants. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'. The quadrants are labeled with I_k Q_k values: top-left is I_k Q_k=10, top-right is I_k Q_k=00, bottom-left is I_k Q_k=11, and bottom-right is I_k Q_k=01. The top of the vertical axis is labeled '+90 degree' and the right of the horizontal axis is labeled '0 degree'. Each quadrant contains a 16x16 grid of points, each labeled with a 6-bit binary sequence. The label 'J.83(07)_FC.7' is in the bottom right corner.](5fdd55201f3f090a54d10ffe9de2f068_img.jpg)
+
+Constellation chart for 256-QAM showing 256 points in a grid across four quadrants. The horizontal axis is labeled 'I' and the vertical axis is labeled 'Q'. The quadrants are labeled with I\_k Q\_k values: top-left is I\_k Q\_k=10, top-right is I\_k Q\_k=00, bottom-left is I\_k Q\_k=11, and bottom-right is I\_k Q\_k=01. The top of the vertical axis is labeled '+90 degree' and the right of the horizontal axis is labeled '0 degree'. Each quadrant contains a 16x16 grid of points, each labeled with a 6-bit binary sequence. The label 'J.83(07)\_FC.7' is in the bottom right corner.
+
+Figure C.7 – Part 2: Constellation chart for 256-QAM
+
+#### C.6.4 Roll-off factor
+
+Prior to modulation, the I and Q signals shall be square-root raised cosine filtered. The roll-off factor shall be 0.13.
+
+The square-root raised cosine filter shall have a theoretical function defined by the following formulae:
+
+$$H(f)=1 \text{ for } |f|<f_N(1-\alpha)$$
+
+$$H(f)=\left[\frac{1}{2}+\frac{1}{2}\sin\frac{\pi}{2f_N}\left[\frac{f_N-|f|}{\alpha}\right]\right]^{1/2} \text{ for } f_N(1-\alpha)\leq|f|\leq f_N(1+\alpha), H(f)=0 \text{ for } |f|>f_N(1+\alpha)$$
+
+where:
+
+$$f_N=\frac{1}{2T_s}=\frac{R_s}{2} \text{ is the Nyquist frequency and roll-off factor } \alpha=0.13$$
+
+NOTE – Transmission filter characteristics are given in the following subclause. The roll-off factor applies under the condition with adjacent channel signals interference (i.e., from TV signal, etc.) and with the specified baseband filter characteristics.
+
+#### C.6.5 Baseband filter characteristics
+
+The template given in Figure C.8 shall be used as a minimum requirement for hardware implementation of the Nyquist filter. This template takes into account not only the design limitations of the digital filter, but also the artifacts coming from the analogue processing components of the system (e.g., D/A conversion, analogue filtering, etc.).
+
+The value of in-band ripple  $r_m$  in the pass-band up to  $(1-\alpha)f_N$  shall be lower than 0.4 dB. The out-band rejection shall be greater than 43 dB. The ripple  $r_N$  at the Nyquist frequency  $f_N$  shall be lower than 1.0 dB.
+
+The filter shall be phase-linear with the group delay ripple  $\leq 1.0 T_s$  (ns) in the pass-band up to  $(1-\alpha)f_N$  and  $\leq 2.0 T_s$  (ns) at  $f_N$ ,
+
+where:
+
+$$T_s=\frac{1}{R_s} \text{ is the symbol period}$$
+
+NOTE – The values for in-band ripple and out-of-band rejection given in this Annex are subject to the operation condition of the cable systems and may require further study.
+
+![Graph of H(f) vs Frequency showing amplitude characteristics of a half-Nyquist baseband filter. The passband from f0 to 0.87 fN has an in-band ripple rm ≤ 0.4 dB. The transition band from 0.87 fN to 1.13 fN has a ripple rN. The stopband from 1.13 fN onwards has an out-of-band rejection ≤ 43 dB. The Nyquist frequency fN is marked on the x-axis.](35135a8841884b7bb6fa58c3d9665c13_img.jpg)
+
+The figure shows the amplitude response  $H(f)$  of a half-Nyquist baseband filter. The x-axis represents Frequency, with key points marked as  $f_0$ ,  $0.87 f_N$ ,  $f_N$ , and  $1.13 f_N$ . The y-axis represents the gain in dB, with a reference line at 0 dB. The passband, from  $f_0$  to  $0.87 f_N$ , has an in-band ripple  $r_m \leq 0.4$  dB. The transition band, from  $0.87 f_N$  to  $1.13 f_N$ , has a ripple  $r_N$ . The stopband, starting at  $1.13 f_N$ , has an out-of-band rejection  $\leq 43$  dB. A technical code T0903140-95/d35 is present in the bottom right of the graph area.
+
+$f_N$  Nyquist frequency
+
+Graph of H(f) vs Frequency showing amplitude characteristics of a half-Nyquist baseband filter. The passband from f0 to 0.87 fN has an in-band ripple rm ≤ 0.4 dB. The transition band from 0.87 fN to 1.13 fN has a ripple rN. The stopband from 1.13 fN onwards has an out-of-band rejection ≤ 43 dB. The Nyquist frequency fN is marked on the x-axis.
+
+**Figure C.8 – Half-Nyquist baseband filter amplitude characteristics**
+
+# Annex D
+
+## Digital multi-programme System D
+
+(This annex forms an integral part of this Recommendation)
+
+## D.1 Introduction
+
+This Annex derives from work done on digital television terrestrial broadcasting in North America; it describes the framing structure, channel coding and modulation for digital multi-programme television distribution by cable, based on MPEG-2 transport multiplexing, and on 16-VSB (Vestigial SideBand) digital transmission.
+
+## D.2 Cable system concept
+
+The 16-VSB system will support a nominal payload data rate of 38.78 Mbit/s in a 6 MHz channel<sup>1</sup>. A functional block diagram of a representative 16-VSB cable transmitter is shown in Figure D.1. The input to the transmission subsystem from the transport subsystem is equivalent to a nominal 38.78 Mbit/s serial data stream comprised of 188-byte MPEG-compatible data packets, see Reference [2] (including a sync byte and 187 bytes of data)<sup>1</sup>.
+
+The incoming data is randomized and then processed for Forward Error Correction (FEC) in the form of Reed-Solomon (RS) coding (20 RS parity bytes are added to each packet), and 1/12 data field interleaving. The randomization and FEC processes are not applied to the sync byte of the transport packet, which is represented in transmission by a Data Segment Sync signal as described below. Following randomization and forward error correction processing, convolutional byte interleaving is performed and then the data packets are formatted into Data Frames for transmission and Data Segment Sync and Data Field Sync are added.
+
+![Figure D.1: 16-VSB transmitter block diagram. The input is '188 byte MPEG-2 packets (Note 1)'. The signal flows through a 'Data randomizer', 'Reed-Solomon encoder', 'Data interleaver', and 'Mapper'. The 'Mapper' output goes to a 'MUX'. The 'MUX' also receives 'Segment sync' and 'Field sync' inputs. The 'MUX' output goes to 'Pilot insertion', then 'VSB modulator', and finally 'RF up-converter'. The output of the 'RF up-converter' is connected to an antenna. The diagram is labeled T0903590-96/d36.](48f209b7c0c1f91af40cfc3466dbd534_img.jpg)
+
+```
+graph LR; Input[188 byte MPEG-2 packets (Note 1)] --> DR[Data randomizer]; DR --> RSE[Reed-Solomon encoder]; RSE --> DI[Data interleaver]; DI --> M[Mapper]; M --> MUX[MUX]; SS[Segment sync] --> MUX; FS[Field sync] --> MUX; MUX --> PI[Pilot insertion]; PI --> VM[VSB modulator]; VM --> RU[RF up-converter]; RU --> Antenna((Antenna));
+```
+
+Figure D.1: 16-VSB transmitter block diagram. The input is '188 byte MPEG-2 packets (Note 1)'. The signal flows through a 'Data randomizer', 'Reed-Solomon encoder', 'Data interleaver', and 'Mapper'. The 'Mapper' output goes to a 'MUX'. The 'MUX' also receives 'Segment sync' and 'Field sync' inputs. The 'MUX' output goes to 'Pilot insertion', then 'VSB modulator', and finally 'RF up-converter'. The output of the 'RF up-converter' is connected to an antenna. The diagram is labeled T0903590-96/d36.
+
+NOTE 1 – Provided by terrestrial broadcasts, satellite, or local origination.
+
+NOTE 2 – Includes private cable [hotels, apartment buildings, condominiums, and schools, – wired, and MMDS (Multichannel Multipoint Distribution System) – wireless microwave].
+
+Figure D.1 – 16-VSB transmitter (cable or SMATV head-end – Note 2)
+
+<sup>1</sup> Parameter value for 6 MHz channel bandwidth; value can be adjusted to match other channel bandwidths.
+
+## D.3 MPEG-2 transport layer
+
+The MPEG-2 transport layer is defined in Reference [2]. The transport layer for MPEG-2 data is comprised of packets having 188 bytes, with one byte for synchronization purposes, three bytes of header containing service identification, scrambling and control information, followed by 184 bytes of MPEG-2 or auxiliary data.
+
+## D.4 Framing structure
+
+Figure D.2 shows how the data are organized for transmission. Each Data Frame consists of two Data Fields, each containing 313 Data Segments. The first Data Segment of each Data Field is a unique synchronizing signal (Data Field Sync) and includes the training sequence used by the equalizer in the receiver. The remaining 312 Data Segments each carry the equivalent of two 188-byte transport packets plus its associated FEC overhead. The actual data in each Data Segment comes from several transport packets because of the data interleaving. Each Data Segment consists of 832 symbols. The first 4 symbols are transmitted in binary form and provide segment synchronization. This Data Segment Sync signal also represents the sync byte for each of the two 188-byte MPEG-compatible transport packets. The remaining 828 symbols of each Data Segment carry data representing two groups of 187 data bytes each followed by 20 Reed-Solomon bytes. These 828 symbols are transmitted as 16-level signals and therefore carry four bits per symbol. Thus,  $828 \times 4 = 3312$  bits of data are carried in each Data Segment, which exactly matches the requirement to send two protected transport packets:
+
+$$\begin{aligned} 187 \text{ data bytes} + 20 \text{ RS parity bytes} &= 207 \text{ bytes} \\ 2 \times 207 \text{ bytes} \times 8 \text{ bits/byte} &= 3312 \end{aligned}$$
+
+The exact symbol rate is given by the equation below:
+
+$$S_r(\text{MHz}) = 4.5/286 \times 684 = 10.76 \dots \text{MHz}^1$$
+
+The 16-level symbols combined with the binary Data Segment Sync and Data Field Sync signals are used to modulate a single carrier in suppressed-carrier mode. Before transmission, however, most of the lower sideband is removed. The resulting spectrum is flat, except for the band edges where a nominal square-root raised-cosine response results in 620 kHz transition regions. The nominal VSB transmission spectrum is shown in Figure D.3<sup>1</sup>.
+
+At the suppressed-carrier frequency, 310 kHz from the lower band edge, a small pilot is added to the signal.
+
+The cable system may also carry standard television signals on other channels as shown in Figure D.3. The nominal average VSB signal power is 6 dB below peak sync power of standard television signals carried in adjacent channels.
+
+![Diagram of a VSB data frame structure showing segments, symbols, and timing.](38cbce07f83fba6d5a7c46605bd5743f_img.jpg)
+
+The diagram illustrates the structure of a VSB data frame. It is a rectangular block divided into two main horizontal sections. Each section contains a 'Field sync' area at the top, followed by a 'Data + FEC' area. The left side of the frame is labeled 'Segment Sync' and is divided into two parts, each labeled '313 segments'. The top of the frame is labeled '828 symbols' with a small '4' above the left bracket. The right side shows a duration of '24.2 ms' for each of the two main sections. At the bottom, a label indicates '1 segment = 77.3 μs'. The reference code 'T0903600-96/d37' is at the bottom right.
+
+Diagram of a VSB data frame structure showing segments, symbols, and timing.
+
+Figure D.2 – VSB data frame
+
+![Diagram showing VSB and NTSC channel occupancy with frequency markers and carrier labels.](9857175bc98d86591d24a161fe615f12_img.jpg)
+
+This figure shows the frequency occupancy of VSB and NTSC channels. The top part is a graph of amplitude (0 to 1.0) versus frequency. It shows a 'Pilot' signal at the start, a 'Suppressed carrier' at the origin, and a flat-topped signal with rounded edges. Horizontal dimension lines indicate a width of 5.38 and a total width of 6.0, with 0.31 MHz margins on each side. The bottom part is a graph of amplitude versus frequency in MHz. It shows the 'NTSC' channel as a flat-topped signal. Key carriers are marked: 'Visual carrier' at 1.25 MHz, 'Chroma carrier' at 1.75 MHz, and 'Aural carrier' at the right edge. The label 'Frequencies in MHz' is at the bottom. The reference code 'T0903610-96/d38' is at the bottom right.
+
+Diagram showing VSB and NTSC channel occupancy with frequency markers and carrier labels.
+
+Figure D.3 – VSB and NTSC channel occupancy
+
+## D.5 Channel coding
+
+#### D.5.1 Data randomizer
+
+A data randomizer is used on all input data to randomize the data payload (not including Data Field Sync or Data Segment Sync, or RS parity bytes). The data randomizer XOR-s all the incoming data bytes with a 16-bit maximum length PseudoRandom Binary Sequence (PRBS) which is initialized at the beginning of the Data Field. The PRBS is generated in a 16-bit shift register that has 9 feedback taps. Eight of the shift register outputs are selected as the fixed randomizing byte, where each bit from this byte is used to individually XOR the corresponding input data bit. The data bits are XOR-ed MSB to MSB ... LSB to LSB.
+
+The initialization (pre-load) to F180 hex (load to 1) occurs during the Data Segment Sync interval prior to the first Data Segment.
+
+The randomizer generator polynomial and initialization are shown in Figure D.4.
+
+![Diagram of a 16-bit PRBS generator. It consists of 16 flip-flops labeled x^0 to x^16. Feedback taps are taken from x^0, x^3, x^6, x^7, x^9, x^10, x^11, x^12, and x^13. These are XORed together and the result is fed back to the input of x^0. Output taps are taken from x^0, x^1, x^2, x^3, x^4, x^5, x^6, and x^7, labeled D^0 through D^7 respectively. The generator is shifted with the Byte Clock and one 8-bit Byte of data is extracted per cycle.](1ce027dfd26183da52137cf990213724_img.jpg)
+
+Generator polynomial  $G_{(16)} = x^{16} + x^{13} + x^{12} + x^{11} + x^7 + x^6 + x^3 + x + 1$   
+ The initialization (pre-load) occurs during the field sync interval
+
+Initialization to F180 hex (Load to 1)  
+ $x^{16} x^{15} x^{14} x^{13} x^9 x^8$
+
+The generator is shifted with the Byte Clock and one 8-bit Byte of data is extracted per cycle
+
+T0903620-96/d39
+
+Diagram of a 16-bit PRBS generator. It consists of 16 flip-flops labeled x^0 to x^16. Feedback taps are taken from x^0, x^3, x^6, x^7, x^9, x^10, x^11, x^12, and x^13. These are XORed together and the result is fed back to the input of x^0. Output taps are taken from x^0, x^1, x^2, x^3, x^4, x^5, x^6, and x^7, labeled D^0 through D^7 respectively. The generator is shifted with the Byte Clock and one 8-bit Byte of data is extracted per cycle.
+
+**Figure D.4 – Randomizer polynomial**
+
+#### D.5.2 Reed-Solomon encoder
+
+The RS code used in the VSB transmission subsystem is  $t = 10$  (207, 187) code. The RS data block size is 187 bytes, with 20 RS parity bytes added for error correction. Two RS blocks of 207 bytes are transmitted per Data Segment.
+
+The 20 RS parity bytes are sent at the end of each respective group of 187 bytes. The parity generator polynomial and the primitive field generator polynomial are shown in Figure D.5.
+
+$$\begin{aligned}
+ \prod_{i=0}^{i=2t-1} (x + \alpha^i) &= x^{20} + x^{19} \alpha^{17} + x^{18} \alpha^{60} + x^{17} \alpha^{79} + x^{16} \alpha^{50} + x^{15} \alpha^{61} + x^{14} \alpha^{163} + \\
+ &\quad x^{13} \alpha^{26} + x^{12} \alpha^{187} + x^{11} \alpha^{202} + x^{10} \alpha^{180} + x^9 \alpha^{221} + x^8 \alpha^{225} + x^7 \alpha^{83} + \\
+ &\quad x^6 \alpha^{239} + x^5 \alpha^{156} + x^4 \alpha^{164} + x^3 \alpha^{212} + x^2 \alpha^{212} + x^1 \alpha^{188} + \alpha^{190} \\
+ &= x^{20} + 152 x^{19} + 185 x^{18} + 240 x^{17} + 5 x^{16} + 111 x^{15} + 99 x^{14} + \\
+ &\quad 6 x^{13} + 220 x^{12} + 112 x^{11} + 150 x^{10} + 69 x^9 + 36 x^8 + 187 x^7 + \\
+ &\quad 22 x^6 + 228 x^5 + 198 x^4 + 121 x^3 + 121 x^2 + 165 x^1 + 174
+ \end{aligned}$$
+
+![Diagram of a parity generator for Reed-Solomon (207, 187) with t=10. It shows a sequence of 20 stages, each consisting of a multiplication by a fixed alpha element (alpha=174, 165, 121, 121, 240, 185, 152) followed by an addition to a cumulative sum. The input is k=187 data bytes. The output is N-k=20 parity bytes. A gate controls the connection for the first (k) bytes and the last (N-k) bytes. A legend defines the symbols: circle with plus for Mod(256) add, circle with cross for Mod(256) multiply, and a square for store one element. Below the main diagram is a smaller diagram showing the generator polynomial G(x) = x^8 + x^4 + x^3 + x^2 + 1, where each shift produces a field element.](cc98b584f9b31fe69948e3fa65a3ba69_img.jpg)
+
+Primitive field generator polynomial (Galois Field)  
+ $G(256) = x^8 + x^4 + x^3 + x^2 + 1$
+
+Each shift of the generator produces a field element
+
+Diagram of a parity generator for Reed-Solomon (207, 187) with t=10. It shows a sequence of 20 stages, each consisting of a multiplication by a fixed alpha element (alpha=174, 165, 121, 121, 240, 185, 152) followed by an addition to a cumulative sum. The input is k=187 data bytes. The output is N-k=20 parity bytes. A gate controls the connection for the first (k) bytes and the last (N-k) bytes. A legend defines the symbols: circle with plus for Mod(256) add, circle with cross for Mod(256) multiply, and a square for store one element. Below the main diagram is a smaller diagram showing the generator polynomial G(x) = x^8 + x^4 + x^3 + x^2 + 1, where each shift produces a field element.
+
+Figure D.5 – Parity generator polynomial for Reed-Solomon (207, 187) with  $t = 10$
+
+#### D.5.3 Interleaving
+
+The interleaver employed in the VSB transmission system is a 26 data segment (intersegment) convolutional byte interleaver. Interleaving is provided to a depth of about 1/12 of a data field (2 ms deep). Only data bytes are interleaved. The interleaver is synchronized to the first data byte of the data field. The convolutional interleaver is shown in Figure D.6.
+
+![Diagram of a Convolutional interleaver. It shows data being read from a Reed-Solomon encoder and written into a series of delay lines (1, 2, 3, ..., 51, (B=)52). The delay lines are of varying lengths: line 1 has 0 delays, line 2 has M (4 Bytes), line 3 has 2M, and so on, up to line 51 which has (B-2)M, and line 52 which has (B-1)M. The data is then read out from these lines and sent to a mapper. The diagram includes a label 'T0903640-96/d41' and a summary: M = 4, B = 52, N = 208, RS Block = 207, B x M = N.](dbd074feb5cce1300f42f91da8f673d1_img.jpg)
+
+T0903640-96/d41
+
+$M = 4, B = 52, N = 208, \text{RS Block} = 207, B \times M = N$
+
+Diagram of a Convolutional interleaver. It shows data being read from a Reed-Solomon encoder and written into a series of delay lines (1, 2, 3, ..., 51, (B=)52). The delay lines are of varying lengths: line 1 has 0 delays, line 2 has M (4 Bytes), line 3 has 2M, and so on, up to line 51 which has (B-2)M, and line 52 which has (B-1)M. The data is then read out from these lines and sent to a mapper. The diagram includes a label 'T0903640-96/d41' and a summary: M = 4, B = 52, N = 208, RS Block = 207, B x M = N.
+
+**Figure D.6 – Convolutional interleaver**
+
+#### D.5.4 Data segment sync
+
+The multi-level data is passed through a multiplexer that inserts the various synchronization signals (Data Segment Sync and Data Field Sync).
+
+A two-level (binary) 4-symbol Data Segment Sync is inserted into the 16-level digital data stream at the beginning of each Data Segment. (The MPEG sync byte is replaced by Data Segment Sync.) The Data Segment Sync embedded in random data is shown in Figure D.7.
+
+A complete segment consists of 832 symbols: 4 symbols for Data Segment Sync, and 828 data plus parity symbols. The Data Segment Sync is binary (2-level). The same sync pattern occurs regularly at 77.3 µs intervals, and is the only signal repeating at this rate. Unlike the data, the four symbols for Data Segment Sync are not Reed-Solomon encoded, nor are they interleaved. The Data Segment Sync pattern is a 1001 pattern, as shown in Figure D.7.
+
+#### D.5.5 Data field sync
+
+The data are not only divided into Data Segments, but also into Data Fields, each consisting of 313 segments. Each Data Field (24.2 ms) starts with one complete Data Segment of Data Field Sync, as shown in Figure D.8. Each symbol represents one bit of data (2-level). The 832 symbols in this segment are defined below. See Figure D.8.
+
+##### D.5.5.1 Sync
+
+This corresponds to Data Segment Sync and is defined as 1001.
+
+##### D.5.5.2 PN511
+
+This pseudo-random sequence is defined as  $x^9 + x^7 + x^6 + x^4 + x^3 + x + 1$  with a pre-load value of 010000000.
+
+The generator for the PN511 sequence is shown in Figure D.9.
+
+##### D.5.5.3 PN63
+
+This pseudo-random sequence is repeated three times. It is defined as  $x^6 + x + 1$  with a pre-load value of 100111. The middle PN63 is inverted on every other Data Field Sync.
+
+The generator for the PN63 sequence is shown in Figure D.9.
+
+![Diagram of a 16-VSB data segment showing levels before pilot addition, data segment sync, data + FEC, and symbol counts.](62039fd2a1ef7b03f84c0fe5d8911860_img.jpg)
+
+This diagram illustrates the structure of a 16-VSB data segment. The vertical axis represents signal levels, ranging from -15 to +15 in increments of 2, with a note indicating these are "Levels before pilot addition (Pilot = 2.5)". The horizontal axis represents the sequence of symbols. The segment is composed of three main parts: a 4-symbol "Data segment SYNC" at the beginning, an 828-symbol "Data + FEC" section in the middle, and another 4-symbol "Data segment SYNC" at the end. The total length of the data segment is 832 symbols. The "Data + FEC" section is shown with a sawtooth pattern, indicating a sequence of symbols. The diagram is labeled T0903660-96/d42.
+
+Diagram of a 16-VSB data segment showing levels before pilot addition, data segment sync, data + FEC, and symbol counts.
+
+Figure D.7 – 16-VSB data segment
+
+![Diagram of a 16-VSB data field sync showing levels before pilot addition, sync symbols, and various data fields (PN511, PN63, VSB mode, Reserved) with their respective symbol counts.](4666738057044ad78ced4dbbc0c1bfb3_img.jpg)
+
+This diagram illustrates the structure of a 16-VSB data field sync. The vertical axis represents signal levels, ranging from -15 to +15 in increments of 2, with a note indicating these are "Levels before pilot addition (Pilot = 2.5)". The horizontal axis represents the sequence of symbols. The segment is composed of several parts: a 4-symbol "Sync" at the beginning, followed by a 511-symbol "PN511" field, three 63-symbol "PN63" fields, a 24-symbol "VSB mode" field, and a 104-symbol "Reserved" field. The total length of the data field is 832 symbols. The diagram is labeled T0903670-96/d43.
+
+Diagram of a 16-VSB data field sync showing levels before pilot addition, sync symbols, and various data fields (PN511, PN63, VSB mode, Reserved) with their respective symbol counts.
+
+Figure D.8 – 16-VSB data field sync
+
+![Two diagrams of PN sequence generators. The top diagram shows a 6-bit shift register with taps at the 1st, 2nd, and 5th positions connected to an XOR gate, producing a 63PN sequence with polynomial x^6 + x + 1 and pre-load 100111. The bottom diagram shows a 10-bit shift register with taps at the 1st, 2nd, 4th, 5th, and 8th positions connected to a chain of XOR gates, producing a 511PN sequence with polynomial x^9 + x^7 + x^6 + x^4 + x^3 + x + 1 and pre-load 010000000. Both diagrams include 'Shift' arrows and 'Output' labels. The bottom diagram is labeled T0903680-96/d44.](4162c218fc7881cd90fc9574e07d2327_img.jpg)
+
+Two diagrams of PN sequence generators. The top diagram shows a 6-bit shift register with taps at the 1st, 2nd, and 5th positions connected to an XOR gate, producing a 63PN sequence with polynomial x^6 + x + 1 and pre-load 100111. The bottom diagram shows a 10-bit shift register with taps at the 1st, 2nd, 4th, 5th, and 8th positions connected to a chain of XOR gates, producing a 511PN sequence with polynomial x^9 + x^7 + x^6 + x^4 + x^3 + x + 1 and pre-load 010000000. Both diagrams include 'Shift' arrows and 'Output' labels. The bottom diagram is labeled T0903680-96/d44.
+
+**Figure D.9 – Field sync PN sequence generators**
+
+##### **D.5.5.4 VSB mode**
+
+These 24 bits determine the VSB mode for the data in the frame. The first two bytes are reserved. The suggested fill pattern is 0000111100001111. The next byte is defined as:
+
+P A B C P A B C
+
+where P is the even parity bit, the MSB of the byte, and A, B, C are the actual mode bits.
+
+P A B C
+
+0 0 0 0 2 VSB
+
+1 0 0 1 4 VSB
+
+1 0 1 0 8 VSB
+
+0 0 1 1 Reserved
+
+1 1 0 0 16-VSB Cable
+
+0 1 0 1 8-VSB Terrestrial (Note) (trellis coded)
+
+0 1 1 0 Reserved
+
+1 1 1 1 Reserved
+
+NOTE – In the 8-VSB terrestrial mode, the preceding bits are defined as:
+
+0 0 0 0 P A B C P A B C 1 1 1 1
+
+##### **D.5.5.5 Reserved**
+
+The last 104 bits is reserved space. It is suggested that this be filled with a continuation of the PN63 sequence.
+
+All sequences are pre-loaded before the beginning of the Data Field Sync.
+
+Like the Data Segment Sync, the Data Field Sync is not Reed-Solomon encoded, nor is it interleaved.
+
+### D.6 Modulation
+
+#### D.6.1 Bit-to-symbol mapping
+
+Figure D.10 shows the mapping of the outputs of the interleaver to the nominal signal levels of ( $\pm 1, \pm 3, \pm 5, \pm 7, \pm 9, \pm 11, \pm 13, \pm 15$ ). As shown in Figures D.7 and D.8, the nominal levels of Data Segment Sync and Data Field Sync are  $-9$  and  $+9$ .
+
+![Diagram of the 16-VSB mapper showing byte-to-symbol conversion and the mapping table.](0a73b03fba21af142d619a9a662e6490_img.jpg)
+
+The diagram illustrates the 16-VSB mapper process. On the left, a 'Byte to symbol conversion' table shows bytes 0-7 being converted to symbols  $x_{a2}, x_{b2}, x_{c2}, x_{d2}$  (2nd Nibble) and  $x_{a1}, x_{b1}, x_{c1}, x_{d1}$  (1st Nibble). The MSB is indicated for the first nibble and the LSB for the second. These symbols are then mapped to nominal signal levels using a table with columns  $x_a, x_b, x_c, x_d$  and the resulting signal level.
+
+| $x_a$ | $x_b$ | $x_c$ | $x_d$ | 0   |
+|-------|-------|-------|-------|-----|
+| 1     | 1     | 1     | 1     | +15 |
+| 1     | 1     | 1     | 0     | +13 |
+| 1     | 1     | 0     | 1     | +11 |
+| 1     | 1     | 0     | 0     | +9  |
+| 1     | 0     | 1     | 1     | +7  |
+| 1     | 0     | 1     | 0     | +5  |
+| 1     | 0     | 0     | 1     | +3  |
+| 1     | 0     | 0     | 0     | +1  |
+| 0     | 1     | 1     | 1     | -1  |
+| 0     | 1     | 1     | 0     | -3  |
+| 0     | 1     | 0     | 1     | -5  |
+| 0     | 1     | 0     | 0     | -7  |
+| 0     | 0     | 1     | 1     | -9  |
+| 0     | 0     | 1     | 0     | -11 |
+| 0     | 0     | 0     | 1     | -13 |
+| 0     | 0     | 0     | 0     | -15 |
+
+T0903650-96/d45
+
+Diagram of the 16-VSB mapper showing byte-to-symbol conversion and the mapping table.
+
+Figure D.10 – 16-VSB mapper
+
+#### D.6.2 Pilot addition
+
+A small in-phase pilot is added to the data signal. The frequency of the pilot is the same as the suppressed-carrier frequency as shown in Figure D.3. This may be generated in the following manner. A small (digital) DC level (2.5) is added to every symbol (data and synchs) of the digital baseband data plus sync signal ( $\pm 1, \pm 3, \pm 5, \pm 7, \pm 9, \pm 11, \pm 13, \pm 15$ ). The power of the pilot is 11.3 dB below the average data signal power.
+
+#### D.6.3 16-VSB modulation method
+
+The VSB modulator receives the 10.76 Msymbols/s, 16-level composite data signal (pilot and synchs added). The digital multi-programme system performance is based on a linear-phase raised-cosine Nyquist filter response in the concatenated transmitter and receiver, as shown in Figure D.11<sup>1</sup>. The system filter response is essentially flat across the entire band, except for the transition regions at each end of the band. Nominally, the roll-off in the transmitter has the response of a linear-phase square-root raised-cosine filter. Tolerances, both in-band and out-of-band, are under study.
+
+![Figure D.11: Nominal VSB system channel response (linear-phase raised-cosine Nyquist filter).](64aba6d3bacc69b7b90f08e02f2d5efe_img.jpg)
+
+This graph shows the magnitude response of a linear-phase raised-cosine Nyquist filter. The vertical axis represents the gain, with markers at 0, 0.5, and 1.0. The horizontal axis represents frequency. The filter has a flat passband at a gain of 1.0. The roll-off region is defined by a parameter  $d = 0.31 \text{ MHz}$ . The total width of the filter's transition region is  $6 \text{ MHz}$ . A narrower width of  $5.38 \text{ MHz}$  is also indicated. The roll-off factor is given as  $R = 0.1152$ . The identifier T0903690-96/d46 is present in the bottom right corner.
+
+Figure D.11: Nominal VSB system channel response (linear-phase raised-cosine Nyquist filter).
+
+**Figure D.11 – Nominal VSB system channel response  
+(linear-phase raised-cosine Nyquist filter)**
+
+#### D.6.4 Up-conversion
+
+The modulation process is usually accomplished at an IF frequency. The modulated IF is then up-converted to the final frequency carried by the cable system.
+
+### D.7 16-VSB cable receiver
+
+The 16-VSB cable receiver is shown in Figure D.12. All of the inverse functions of the transmitter are performed in the receiver: down conversion (tuner), detection, sync and timing recovery, de-interleaving, Reed-Solomon forward error correction, and data de-randomization.
+
+In addition, an equalizer removes intersymbol interference making use of the data field sync as a training reference signal, and a phase tracker reduces the effect of phase-noise of the local oscillator of the tuner. Following the phase tracker is the slicer to recover the data from the multi-level symbols.
+
+The demodulating carrier is recovered from the pilot and the sync and clock are recovered from the segment sync.
+
+The receiver may be fed with cable mode signals from the cable distribution system or, if the receiver is a terrestrial broadcast receiver, may also be fed from 8-VSB trellis-coded terrestrial broadcasts, or from private cable sources (SMATV or MMDS, or other).
+
+![Figure D.12: 16-VSB receiver block diagram.](b06a4c871dfd0ce034cf801519d0039a_img.jpg)
+
+This block diagram illustrates the signal processing flow in a 16-VSB receiver. The input signal enters a 'Tuner' block. The output of the tuner is then processed by an 'IF filter & synchronous detector' block, which outputs an 'I' (in-phase) signal. This 'I' signal is followed by an 'Equalizer' block, which also outputs an 'I' signal. This is followed by a 'Phase tracker' block, which outputs an 'I' signal. The next block is a 'Slicer', which outputs an 'I' signal. This is followed by a 'Data de-interleaver' block, then a 'Reed-Solomon Forward Error Corrector' block, and finally a 'Data de-randomizer' block, which produces the 'Data out'. A 'Sync & timing' block is connected to the output of the 'IF filter & synchronous detector' and provides timing information to the subsequent blocks. The identifier T0903700-96/d47 is present in the bottom right corner.
+
+Figure D.12: 16-VSB receiver block diagram.
+
+**Figure D.12 – 16-VSB receiver**
+
+## D.8 Other VSB modes
+
+#### D.8.1 Introduction
+
+Subclause D.5.5.4 above identified the VSB mode bits in the VSB data field sync interval for VSB modes 2-VSB, 4-VSB, 8-VSB, 16-VSB, and 8-VSB (trellis coded). This entire Annex up to this point has described the 16-VSB mode processes including the 188-byte MPEG input packets, data frame structure, data randomizer, Reed-Solomon Forward Error Correction (FEC), byte interleaving, mapper, data segment sync, data field sync, VSB modulation, and the 16-VSB receiver.
+
+#### D.8.2 Overview of VSB modes
+
+The group of VSB modes form a family with a high degree of commonality of processes. Each mode of the family uses the same symbol rate synchronizing, spectrum shaping, and channel bandwidth. The difference between the modes is due to the variation of bits per symbol and the consequent payload data rate that can be accommodated. Table D.1 shows the relationships.
+
+**Table D.1 – VSB mode comparison table**
+
+| VSB mode        | Transport data rate | Noise burst tolerance | C/N threshold |
+|-----------------|---------------------|-----------------------|---------------|
+| 2-VSB           | 9.7 Mbit/s          | 387 $\mu$ sec         | 10 dB         |
+| 4-VSB           | 19.39 Mbit/s        | 193 $\mu$ sec         | 16 dB         |
+| 8-VSB           | 29.09 Mbit/s        | 129 $\mu$ sec         | 22 dB         |
+| 16-VSB          | 38.79 Mbit/s        | 97 $\mu$ sec          | 28 dB         |
+| 8-VSB (Trellis) | 19.39 Mbit/s        | 193 $\mu$ sec         | 15 dB         |
+
+Each of the VSB modes is treated in the following subclauses.
+
+#### D.8.3 MPEG-2 transport layer
+
+As in clause D.3 above, the transport layer provides 188-byte packets.
+
+#### D.8.4 Framing structure
+
+Figure D.2 shows the data symbols, data segments, and data field organization which is common to all VSB modes. Table D.2 shows the relationship between Reed-Solomon FEC protected MPEG-2 packets and data segments and VSB modes.
+
+**Table D.2 – Comparison table of data frame – MPEG packet-VSB mode**
+
+| VSB mode | Bits/symbol | Bits/segment | FEC protected MPEG packets/segment |
+|----------|-------------|--------------|------------------------------------|
+| 2        | 1           | 828          | 1/2                                |
+| 4        | 2           | 1656         | 1                                  |
+| 8        | 3           | 2484         | 1 1/2                              |
+| 16       | 4           | 3312         | 2                                  |
+| 8T       | 2           | 1656         | 1                                  |
+
+#### D.8.5 Channel coding
+
+##### D.8.5.1 Data randomizer
+
+Data randomizing for 2-VSB, 4-VSB, 8-VSB and 8-VSB (trellis) is accomplished as in clause D.5.1.
+
+##### D.8.5.2 Reed-Solomon encoder
+
+The RS FEC process for 2-VSB, 4-VSB, 8-VSB, and 8-VSB (trellis coded) is as described in clause D.5.2.
+
+##### D.8.5.3 Interleaving
+
+Interleaving for 2-VSB, 4-VSB, 8-VSB, and 8-VSB (trellis coded) is as described in clause D.5.3. Because bit rates are different for the various VSB modes, the performance with noise bursts varies as shown in Table D.1.
+
+##### D.8.5.4 Data segment sync
+
+The data segment sync is common to all VSB modes. The particulars of the data segment sync are described in clause D.5.4. However, the embedding of the sync in the multi-level symbol data varies. This is shown for 2-VSB, 4-VSB, 8-VSB and 8-VSB (trellis coded) in Figures D.13, D.14, D.15, and D.16 respectively.
+
+![Figure D.13 – 2-VSB data segment diagram showing signal levels and symbol counts.](63fc2a3d211283bdef0682dbd6d01a9c_img.jpg)
+
+The diagram illustrates the signal levels and symbol structure for a 2-VSB data segment. The vertical axis represents signal levels, with a reference line at 0, a peak level at +1, and a trough level at -1. An arrow on the left points to the -1 level with the text "Levels before pilot addition (Pilot = 0.3125)". The horizontal axis represents the sequence of symbols. The segment begins and ends with a "Data segment SYNC" block, each consisting of 4 symbols. The signal in these sync blocks drops from 0 to -1 and back to 0. Between the sync blocks is a "Data + FEC" section containing 828 symbols, represented by a sawtooth waveform. A bracket below the horizontal axis spans the entire segment (sync + data + sync) and is labeled "Data segment" and "832 symbols". The identifier "T0903710-96/d48" is located in the bottom right corner.
+
+Figure D.13 – 2-VSB data segment diagram showing signal levels and symbol counts.
+
+Figure D.13 – 2-VSB data segment
+
+![Diagram of a 4-VSB data segment showing amplitude levels and symbol counts.](a7f9e5d1862146a136ba5ea891f15f17_img.jpg)
+
+This diagram illustrates the structure of a 4-VSB data segment. The vertical axis represents amplitude levels, with labels at +3, +1, -1, and -3. The horizontal axis represents the sequence of symbols. The segment is composed of three main parts: a 4-symbol 'Data segment SYNC' at the beginning, an 828-symbol 'Data + FEC' section in the middle, and another 4-symbol 'Data segment SYNC' at the end. The total length of the 'Data segment' is 832 symbols. The 'Data + FEC' section is shown with a break in the middle, indicated by two parallel diagonal lines. The levels shown are 'Levels before pilot addition (Pilot = 0.625)'. A reference code 'T0903730-96/d49' is located in the bottom right corner.
+
+Diagram of a 4-VSB data segment showing amplitude levels and symbol counts.
+
+Figure D.14 – 4-VSB data segment
+
+![Diagram of an 8-VSB data segment showing amplitude levels and symbol counts.](e9bc763ebea46fe89aede23775517f44_img.jpg)
+
+This diagram illustrates the structure of an 8-VSB data segment. The vertical axis represents amplitude levels, with labels at +7, +5, +3, +1, -1, -3, -5, and -7. The horizontal axis represents the sequence of symbols. The segment is composed of three main parts: a 4-symbol 'Data segment SYNC' at the beginning, an 828-symbol 'Data + FEC' section in the middle, and another 4-symbol 'Data segment SYNC' at the end. The total length of the 'Data segment' is 832 symbols. The 'Data + FEC' section is shown with a break in the middle, indicated by two parallel diagonal lines. The levels shown are 'Levels before pilot addition (Pilot = 1.25)'. A reference code 'T0903720-96/d50' is located in the bottom right corner.
+
+Diagram of an 8-VSB data segment showing amplitude levels and symbol counts.
+
+Figure D.15 – 8-VSB data segment
+
+![Figure D.16: 8-VSB data segment (trellis coded). This diagram shows the amplitude levels for a data segment. The vertical axis represents amplitude levels from -7 to +7. The horizontal axis represents symbols. The segment consists of three parts: a 4-symbol 'Data segment SYNC' at the beginning, an 828-symbol 'Data + FEC' section in the middle, and another 4-symbol 'Data segment SYNC' at the end. The total length is 832 symbols. The amplitude levels for the sync symbols are shown as a step function, dropping from +5 to -5 and back to +5. The data symbols are represented by horizontal lines at various levels. A note on the left indicates 'Levels before pilot addition (Pilot = 1.25)'. A reference code 'T0903740-96/d51' is at the bottom right.](1dea2e515f706e8044ae79339efaa36c_img.jpg)
+
+Figure D.16: 8-VSB data segment (trellis coded). This diagram shows the amplitude levels for a data segment. The vertical axis represents amplitude levels from -7 to +7. The horizontal axis represents symbols. The segment consists of three parts: a 4-symbol 'Data segment SYNC' at the beginning, an 828-symbol 'Data + FEC' section in the middle, and another 4-symbol 'Data segment SYNC' at the end. The total length is 832 symbols. The amplitude levels for the sync symbols are shown as a step function, dropping from +5 to -5 and back to +5. The data symbols are represented by horizontal lines at various levels. A note on the left indicates 'Levels before pilot addition (Pilot = 1.25)'. A reference code 'T0903740-96/d51' is at the bottom right.
+
+**Figure D.16 – 8-VSB data segment (trellis coded)**
+
+##### **D.8.5.5 Data field sync**
+
+The data field sync is common to all VSB modes. The particulars of the data field sync are described in clause D.5.5. However, as in the case of the segment sync embedding of the data field sync in the multi-level symbol data varies. This is shown for 2-VSB, 4-VSB, 8-VSB, and 8-VSB (trellis coded) in Figures D.17, D.18, D.19, and D.20, respectively.
+
+![Figure D.17: 2-VSB data field sync. This diagram shows the amplitude levels for a data field sync. The vertical axis represents amplitude levels from -1 to +1. The horizontal axis represents symbols. The total length is 832 symbols. The segment consists of several parts: a 4-symbol 'Sync' at the beginning, a 511-symbol 'PN511' section, three 63-symbol 'PN63' sections, a 24-symbol 'VSB mode' section, and a 104-symbol 'Reserved' section. The amplitude levels for the sync symbols are shown as a step function, dropping from +1 to -1 and back to +1. The data symbols are represented by horizontal lines at various levels. A note on the left indicates 'Levels before pilot addition (Pilot = 0.3125)'. A reference code 'T0903750-96/d52' is at the bottom right.](f217ea7a6e9347a9ca4d6173ed57c33e_img.jpg)
+
+Figure D.17: 2-VSB data field sync. This diagram shows the amplitude levels for a data field sync. The vertical axis represents amplitude levels from -1 to +1. The horizontal axis represents symbols. The total length is 832 symbols. The segment consists of several parts: a 4-symbol 'Sync' at the beginning, a 511-symbol 'PN511' section, three 63-symbol 'PN63' sections, a 24-symbol 'VSB mode' section, and a 104-symbol 'Reserved' section. The amplitude levels for the sync symbols are shown as a step function, dropping from +1 to -1 and back to +1. The data symbols are represented by horizontal lines at various levels. A note on the left indicates 'Levels before pilot addition (Pilot = 0.3125)'. A reference code 'T0903750-96/d52' is at the bottom right.
+
+**Figure D.17 – 2-VSB data field sync**
+
+![Diagram of 4-VSB data field sync showing levels and symbol counts.](6f047db5bd9eab2d3c1a0d2ac59103db_img.jpg)
+
+This diagram illustrates the 4-VSB data field sync structure. The vertical axis represents signal levels before pilot addition, with values +3, +1, -1, and -3. The horizontal axis represents the sequence of symbols, totaling 832 symbols. The sequence is divided into several segments: a 4-symbol 'Sync' segment, a 511-symbol 'PN511' segment, three 63-symbol 'PN63' segments, a 24-symbol 'VSB mode' segment, and a 104-symbol 'Reserved' segment. The 'Sync' segments are shown as rectangular pulses. A note at the bottom left indicates 'Levels before pilot addition (Pilot = 0.625)'. A reference code 'T0903760-96/d53' is located at the bottom right.
+
+| Segment      | Symbol Count |
+|--------------|--------------|
+| Sync         | 4            |
+| PN511        | 511          |
+| PN63         | 63           |
+| PN63         | 63           |
+| PN63         | 63           |
+| VSB mode     | 24           |
+| Reserved     | 104          |
+| <b>Total</b> | <b>832</b>   |
+
+Diagram of 4-VSB data field sync showing levels and symbol counts.
+
+Figure D.18 – 4-VSB data field sync
+
+![Diagram of 8-VSB data field sync showing levels and symbol counts.](9fe11419dec507724d0362eb31c7b217_img.jpg)
+
+This diagram illustrates the 8-VSB data field sync structure. The vertical axis represents signal levels before pilot addition, with values +7, +5, +3, +1, -1, -3, -5, and -7. The horizontal axis represents the sequence of symbols, totaling 832 symbols. The sequence is divided into several segments: a 4-symbol 'Sync' segment, a 511-symbol 'PN511' segment, three 63-symbol 'PN63' segments, a 24-symbol 'VSB mode' segment, and a 104-symbol 'Reserved' segment. The 'Sync' segments are shown as rectangular pulses. A note at the bottom left indicates 'Levels before pilot addition (Pilot = 1.25)'. A reference code 'T0903770-96/d54' is located at the bottom right.
+
+| Segment      | Symbol Count |
+|--------------|--------------|
+| Sync         | 4            |
+| PN511        | 511          |
+| PN63         | 63           |
+| PN63         | 63           |
+| PN63         | 63           |
+| VSB mode     | 24           |
+| Reserved     | 104          |
+| <b>Total</b> | <b>832</b>   |
+
+Diagram of 8-VSB data field sync showing levels and symbol counts.
+
+Figure D.19 – 8-VSB data field sync
+
+![Figure D.20: 8-VSB (trellis coded) data field sync diagram. The diagram shows a sequence of 832 symbols with levels from -7 to +7. It includes a 'Sync' section (4 symbols), 'PN511' (511 symbols), three 'PN63' sections (63 symbols each), 'VSB mode' (24 symbols), 'Reserved' (92 symbols), and a 'Pre-code' section (12 symbols). The 'Pre-code' section is a duplication of the last 12 symbols of the previous segment. The levels before pilot addition (Pilot = 1.25) are indicated below the symbol sequence.](a74fdbc8b78564b89bc1b262cfd995b6_img.jpg)
+
+832 symbols
+
+Pre-code
+
+Levels before pilot addition (Pilot = 1.25)
+
+4 symbols
+
+511 symbols
+
+63 symbols
+
+63 symbols
+
+63 symbols
+
+24 symbols
+
+92 symbols
+
+12 symbols<sup>a)</sup>
+
+T0903780-96/d55
+
+Figure D.20: 8-VSB (trellis coded) data field sync diagram. The diagram shows a sequence of 832 symbols with levels from -7 to +7. It includes a 'Sync' section (4 symbols), 'PN511' (511 symbols), three 'PN63' sections (63 symbols each), 'VSB mode' (24 symbols), 'Reserved' (92 symbols), and a 'Pre-code' section (12 symbols). The 'Pre-code' section is a duplication of the last 12 symbols of the previous segment. The levels before pilot addition (Pilot = 1.25) are indicated below the symbol sequence.
+
+<sup>a)</sup> For trellis coded 8-VSB, the last 12 symbols of the previous segment are duplicated in the last 12 reserved symbols of the field sync.
+
+Figure D.20 – 8-VSB (trellis coded) data field sync
+
+#### D.8.6 Modulation
+
+##### D.8.6.1 Bit to symbol mapping
+
+The bit to symbol mapping for 2-VSB, 4-VSB, 8-VSB, and 8-VSB (trellis coded) is shown in Figures D.21, D.22, D.23 and D.24, respectively. The data symbol levels are  $\pm 1$  for 2-VSB,  $\pm 1, \pm 3$  for 4-VSB, and  $\pm 1, \pm 3, \pm 5, \pm 7$  for 8-VSB and 8-VSB (trellis coded)<sup>2</sup>.
+
+![Figure D.21: 2-VSB mapper diagram. The diagram shows the mapping of 8 bits (x_a1 to x_a8) from a byte to a symbol. The bits are processed through a mapper table to produce a symbol x_a, which is then sent to a MUX. The mapper table shows the mapping of bits 1 and 0 to symbols +1 and -1.](e05434e963901d7e9c0bf5a6758200ed_img.jpg)
+
+Byte to symbol conversion
+
+From byte interleaver
+
+MSB
+
+1st bit
+
+Mapper
+
+$x_a$
+
+To MUX
+
+T0903790-96/d56
+
+LSB
+
+8th bit
+
+|   |          |
+|---|----------|
+| 7 | $x_{a1}$ |
+| 6 | $x_{a2}$ |
+| 5 | $x_{a3}$ |
+| 4 | $x_{a4}$ |
+| 3 | $x_{a5}$ |
+| 2 | $x_{a6}$ |
+| 1 | $x_{a7}$ |
+| 0 | $x_{a8}$ |
+
+|       |    |
+|-------|----|
+| $x_a$ | 0  |
+| 1     | +1 |
+| 0     | -1 |
+
+Figure D.21: 2-VSB mapper diagram. The diagram shows the mapping of 8 bits (x\_a1 to x\_a8) from a byte to a symbol. The bits are processed through a mapper table to produce a symbol x\_a, which is then sent to a MUX. The mapper table shows the mapping of bits 1 and 0 to symbols +1 and -1.
+
+Figure D.21 – 2-VSB mapper
+
+<sup>2</sup> The 8-VSB (trellis coded) mode is described in detail in [b-1].
+
+![Diagram of a 4-VSB mapper. On the left, a 'Byte to symbol conversion' table shows 8 input values (0-7) being converted to 8 symbols (x_a1, x_b1, x_a2, x_b2, x_a3, x_b3, x_a4, x_b4). These are grouped into 4 dibits. The 1st dibit consists of x_a1 and x_b1, and the 4th dibit consists of x_a4 and x_b4. These are fed into a 'Mapper' table which takes x_a and x_b as inputs and produces an output '0' based on the mapping: (1,1) to +3, (1,0) to +1, (0,1) to -1, and (0,0) to -3. The output is then sent 'To MUX'.](7e14467740b2570a44379b347a697921_img.jpg)
+
+Byte to symbol conversion
+
+|   |          |     |
+|---|----------|-----|
+| 7 | $x_{a1}$ | MSB |
+| 6 | $x_{b1}$ |     |
+| 5 | $x_{a2}$ |     |
+| 4 | $x_{b2}$ |     |
+| 3 | $x_{a3}$ |     |
+| 2 | $x_{b3}$ |     |
+| 1 | $x_{a4}$ |     |
+| 0 | $x_{b4}$ |     |
+|   |          | LSB |
+
+From byte interleaver
+
+1st dibit
+
+4th dibit
+
+Mapper
+
+| $x_a$ | $x_b$ | 0  |
+|-------|-------|----|
+| 1     | 1     | +3 |
+| 1     | 0     | +1 |
+| 0     | 1     | -1 |
+| 0     | 0     | -3 |
+
+To MUX
+
+T0903800-96/d57
+
+Diagram of a 4-VSB mapper. On the left, a 'Byte to symbol conversion' table shows 8 input values (0-7) being converted to 8 symbols (x\_a1, x\_b1, x\_a2, x\_b2, x\_a3, x\_b3, x\_a4, x\_b4). These are grouped into 4 dibits. The 1st dibit consists of x\_a1 and x\_b1, and the 4th dibit consists of x\_a4 and x\_b4. These are fed into a 'Mapper' table which takes x\_a and x\_b as inputs and produces an output '0' based on the mapping: (1,1) to +3, (1,0) to +1, (0,1) to -1, and (0,0) to -3. The output is then sent 'To MUX'.
+
+Figure D.22 – 4-VSB mapper
+
+![Diagram of an 8-VSB mapper. On the left, a 'Byte to symbol conversion' table shows 24 input values (0-23) being converted to 24 symbols (x_a1 through x_c8). These are grouped into 8 tribits. The 1st tribit consists of x_a1, x_b1, and x_c1, and the 8th tribit consists of x_a8, x_b8, and x_c8. These are fed into a 'Mapper' table which takes x_a, x_b, and x_c as inputs and produces an output '0' based on the mapping: (1,1,1) to +7, (1,1,0) to +5, (1,0,1) to +3, (1,0,0) to +1, (0,1,1) to -1, (0,1,0) to -3, (0,0,1) to -5, and (0,0,0) to -7. The output is then sent 'To MUX'.](fed4a04822c24fb22cca3a14f4ddae83_img.jpg)
+
+Byte to symbol conversion
+
+|   |          |     |
+|---|----------|-----|
+| 7 | $x_{a1}$ | MSB |
+| 6 | $x_{b1}$ |     |
+| 5 | $x_{c1}$ |     |
+| 4 | $x_{a2}$ |     |
+| 3 | $x_{b2}$ |     |
+| 2 | $x_{c2}$ |     |
+| 1 | $x_{a3}$ |     |
+| 0 | $x_{b3}$ |     |
+| 7 | $x_{c3}$ |     |
+| 6 | $x_{a4}$ |     |
+| 5 | $x_{b4}$ |     |
+| 4 | $x_{c4}$ |     |
+| 3 | $x_{a5}$ |     |
+| 2 | $x_{b5}$ |     |
+| 1 | $x_{c5}$ |     |
+| 0 | $x_{a6}$ |     |
+| 7 | $x_{b6}$ |     |
+| 6 | $x_{c6}$ |     |
+| 5 | $x_{a7}$ |     |
+| 4 | $x_{b7}$ |     |
+| 3 | $x_{c7}$ |     |
+| 2 | $x_{a8}$ |     |
+| 1 | $x_{b8}$ |     |
+| 0 | $x_{c8}$ |     |
+|   |          | LSB |
+
+From byte interleaver
+
+1st tribit
+
+2nd tribit
+
+8th tribit
+
+Mapper
+
+| $x_a$ | $x_b$ | $x_c$ | 0  |
+|-------|-------|-------|----|
+| 1     | 1     | 1     | +7 |
+| 1     | 1     | 0     | +5 |
+| 1     | 0     | 1     | +3 |
+| 1     | 0     | 0     | +1 |
+| 0     | 1     | 1     | -1 |
+| 0     | 1     | 0     | -3 |
+| 0     | 0     | 1     | -5 |
+| 0     | 0     | 0     | -7 |
+
+To MUX
+
+T0903810-96/d58
+
+Diagram of an 8-VSB mapper. On the left, a 'Byte to symbol conversion' table shows 24 input values (0-23) being converted to 24 symbols (x\_a1 through x\_c8). These are grouped into 8 tribits. The 1st tribit consists of x\_a1, x\_b1, and x\_c1, and the 8th tribit consists of x\_a8, x\_b8, and x\_c8. These are fed into a 'Mapper' table which takes x\_a, x\_b, and x\_c as inputs and produces an output '0' based on the mapping: (1,1,1) to +7, (1,1,0) to +5, (1,0,1) to +3, (1,0,0) to +1, (0,1,1) to -1, (0,1,0) to -3, (0,0,1) to -5, and (0,0,0) to -7. The output is then sent 'To MUX'.
+
+Figure D.23 – 8-VSB mapper
+
+![Block diagram of an 8-VSB transmitter showing the pre-coder, trellis encoder, and mapper. The diagram includes a byte interleaver feeding into 12 parallel paths. Path 1 consists of a 'Byte to dibit converter #1' followed by a 'Trellis encoder and pre-coder #1'. Paths 2 through 12 consist of two parallel blocks each. The outputs of these blocks are fed into a 'Mapper' which contains a lookup table. A detailed view of the pre-coder shows the MSB (x2) and LSB (x1) inputs, with the MSB being XORed with a delayed version of itself and then the LSB being added to the result to produce z2, z1, and z0 outputs. The delay is 12 symbols.](5a9cdc1fed33ae8fb871a8cd4d591729_img.jpg)
+
+The diagram illustrates the 8-VSB transmitter architecture. Data from a byte interleaver is distributed across 12 parallel processing paths. Path 1 contains a 'Byte to dibit converter #1' which outputs  $x_2$  and  $x_1$  to a 'Trellis encoder and pre-coder #1', which in turn outputs  $z_2$ ,  $z_1$ , and  $z_0$ . Paths 2 through 12 each consist of two parallel blocks. All 12 sets of outputs are fed into a 'Mapper' block. The Mapper contains a lookup table:
+
+| $Z_2$ | $Z_1$ | $Z_0$ | 0  |
+|-------|-------|-------|----|
+| 1     | 1     | 1     | +7 |
+| 1     | 1     | 0     | +5 |
+| 1     | 0     | 1     | +3 |
+| 1     | 0     | 0     | +1 |
+| 0     | 1     | 1     | -1 |
+| 0     | 1     | 0     | -3 |
+| 0     | 0     | 1     | -5 |
+| 0     | 0     | 0     | -7 |
+
+The Mapper outputs are sent 'To MUX'. A detailed view of the pre-coder (labeled T0903820-96/d59) shows the MSB ( $x_2$ ) and LSB ( $x_1$ ) inputs. The MSB is XORed with a 12-symbol delayed version of itself (indicated by 'D' blocks and '(D = 12 symbols delay)') to produce  $z_2$ . The LSB ( $x_1$ ) is then added to  $z_2$  to produce  $z_1$ . Finally,  $z_1$  is XORed with its 12-symbol delayed version to produce  $z_0$ .
+
+Block diagram of an 8-VSB transmitter showing the pre-coder, trellis encoder, and mapper. The diagram includes a byte interleaver feeding into 12 parallel paths. Path 1 consists of a 'Byte to dibit converter #1' followed by a 'Trellis encoder and pre-coder #1'. Paths 2 through 12 consist of two parallel blocks each. The outputs of these blocks are fed into a 'Mapper' which contains a lookup table. A detailed view of the pre-coder shows the MSB (x2) and LSB (x1) inputs, with the MSB being XORed with a delayed version of itself and then the LSB being added to the result to produce z2, z1, and z0 outputs. The delay is 12 symbols.
+
+Figure D.24 – 8-VSB (pre-coder, trellis encoder) mapper rate = 2/3
+
+##### D.8.6.2 Pilot addition
+
+The pilot addition may be done in the same manner as in clause D.6.2 by adding a small DC level to the baseband symbols (data and sync). The value of the DC level is 0.3125 for 2-VSB, 0.625 for 4-VSB, 1.25 for 8-VSB and 8-VSB (trellis coded).
+
+This is shown in Figures D.13, D.14, D.15 and D.16 for 2-VSB, 4-VSB, 8-VSB and 8-VSB (trellis coded), respectively.
+
+##### D.8.6.3 VSB modulation method
+
+The modulation method for all VSB systems is accomplished in the same manner as in clause D.6.3. The overall channel frequency response is shaped as in Figure D.11.
+
+##### D.8.6.4 Up-conversion
+
+The modulation method is usually accomplished at an IF frequency. The modulated IF is then up-converted to the final channel frequency of the RF transmission system.
+
+#### D.8.7 VSB receiver
+
+The VSB receiver has all the inverse functions of the transmitter. The VSB mode of transmission is indicated to the receiver in the manner described in clause D.5.5.4. The receiver functions are then adjusted to accommodate to the various required data slice levels and to the differing incoming bit rates<sup>3</sup>.
+
+<sup>3</sup> The 8-VSB (trellis coded) receiving process is described in detail in [b-2] of the Bibliography.
+
+# Bibliography
+
+- [b-1] Advanced Television Systems Committee (ATSC): *Digital television standard, Washington D.C., September 1995.*
+- [b-2] Advanced Television Systems Committee (ATSC): *Guide to the use of the ATSC digital standard, Washington D.C., October 1995.*
+
+
+
+# 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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+++ b/marked/J/T-REC-J.84-200103-I_PDF-E/raw.md
@@ -0,0 +1,1060 @@
+
+
+![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
+
+**J.84**
+
+(03/2001)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Digital transmission of television signals
+
+---
+
+**Distribution of digital multi-programme signals  
+for television, sound and data services through  
+SMATV networks**
+
+ITU-T Recommendation J.84
+
+(Formerly CCITT Recommendation)
+
+---
+
+# ITU-T J-SERIES RECOMMENDATIONS
+
+# CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS
+
+|                                                                                                 |                  |
+|-------------------------------------------------------------------------------------------------|------------------|
+| General Recommendations                                                                         | J.1–J.9          |
+| General specifications for analogue sound-programme transmission                                | J.10–J.19        |
+| Performance characteristics of analogue sound-programme circuits                                | J.20–J.29        |
+| Equipment and lines used for analogue sound-programme circuits                                  | J.30–J.39        |
+| Digital encoders for analogue sound-programme signals                                           | J.40–J.49        |
+| Digital transmission of sound-programme signals                                                 | J.50–J.59        |
+| Circuits for analogue television transmission                                                   | J.60–J.69        |
+| Analogue television transmission over metallic lines and interconnection with radio-relay links | J.70–J.79        |
+| <b>Digital transmission of television signals</b>                                               | <b>J.80–J.89</b> |
+| Ancillary digital services for television transmission                                          | J.90–J.99        |
+| Operational requirements and methods for television transmission                                | J.100–J.109      |
+| Interactive systems for digital television distribution                                         | J.110–J.129      |
+| Transport of MPEG-2 signals on packetised networks                                              | J.130–J.139      |
+| Measurement of the quality of service                                                           | J.140–J.149      |
+| Digital television distribution through local subscriber networks                               | J.150–J.159      |
+| IPCablecom                                                                                      | J.160–J.179      |
+| Miscellaneous                                                                                   | J.180–J.199      |
+| Application for Interactive Digital Television                                                  | J.200–J.209      |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# **Distribution of digital multi-programme signals for television, sound and data services through SMATV networks**
+
+## **Summary**
+
+This Recommendation "Distribution of digital multi-programme signals for television, sound and data services through SMATV networks" covers the definition of the framing structure, channel coding and modulation for digital multi-programme signals for television, sound and data services received from a satellite system and distributed in a transparent way through Satellite Master Antenna Television (SMATV) networks.
+
+This Recommendation defines the required network architecture for SMATV systems and is closely related to ITU-R BO.1211 (applicable to the satellite path) and to ITU-T J.83 (applicable to the cable path).
+
+This Recommendation has four Annexes (A, B, C and D) that provide the specifications for the digital television SMATV systems submitted to the ITU-T. This reflects the fact that standardization of digital SMATV television systems is being addressed for the first time by the ITU-T and that a number of systems had been developed and provisionally implemented when this standardization effort was undertaken by the ITU.
+
+This Recommendation recommends that those implementing new digital multi-programme services on existing and future SMATV networks should use one of the systems whose framing structure, channel coding and modulation are specified in Annexes A, B, C and D.
+
+###### **Source**
+
+ITU-T Recommendation J.84 was revised by ITU-T Study Group 9 (2001-2004) and approved under the WTSA Resolution 1 procedure on 9 March 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      | Scope.....                                                                    | 1    |
+| 2      | References.....                                                               | 1    |
+| 3      | Definitions .....                                                             | 2    |
+| 4      | Symbols and abbreviations .....                                               | 2    |
+| 4.1    | Symbols .....                                                                 | 2    |
+| 4.2    | Abbreviations.....                                                            | 2    |
+| 5      | Digital multi-programme SMATV systems .....                                   | 3    |
+|        | Annex A – Digital multi-programme SMATV System A .....                        | 5    |
+| A.1    | Scope.....                                                                    | 5    |
+| A.2    | References.....                                                               | 5    |
+| A.3    | SMATV distribution system concepts .....                                      | 5    |
+| A.4    | SMATV System A1 .....                                                         | 6    |
+| A.4.1  | Full implementation of SMATV System A1 .....                                  | 6    |
+| A.4.2  | Simplified implementation of SMATV System A1 .....                            | 6    |
+| A.5    | SMATV System A2.....                                                          | 6    |
+| A.5.1  | SMATV-IF .....                                                                | 8    |
+| A.5.2  | SMATV-S.....                                                                  | 8    |
+| A.6    | MPEG-2 transport layer.....                                                   | 9    |
+| A.7    | Framing structure.....                                                        | 9    |
+|        | Appendix A.I – Channel model of SMATV distribution systems.....               | 9    |
+| A.I.1  | Channel model response.....                                                   | 9    |
+| A.I.2  | Definition of adaptive equalization requirements .....                        | 10   |
+|        | Appendix A.II – Examples of 64-QAM and QPSK performance with equalizers ..... | 11   |
+| A.II.1 | SMATV System A1 – Simulation results.....                                     | 12   |
+| A.II.2 | SMATV System A.2 – Simulation results.....                                    | 12   |
+|        | Appendix A.III – Bit rate consideration for SMATV distribution systems.....   | 16   |
+|        | Appendix A.IV .....                                                           | 18   |
+|        | Annex B – Digital multi-programme SMATV System B .....                        | 18   |
+|        | Annex C – Digital multi-programme SMATV System C .....                        | 19   |
+| C.1    | Scope.....                                                                    | 19   |
+| C.2    | SMATV distribution system concept .....                                       | 19   |
+| C.3    | SMATV system C(I).....                                                        | 19   |
+| C.4    | SMATV system C(II) .....                                                      | 20   |
+
+|                                                        | <b>Page</b> |
+|--------------------------------------------------------|-------------|
+| C.5 SMATV system C(III) .....                          | 20          |
+| C.6 MPEG-2 transport layer .....                       | 21          |
+| C.7 Framing structure for channel coding .....         | 21          |
+| Annex D – Digital multi-programme SMATV System D ..... | 21          |
+| D.1 Introduction .....                                 | 21          |
+| D.2 SMATV VSB system concept .....                     | 21          |
+| D.3 SMATV head-end commonalities .....                 | 22          |
+| D.4 Conclusion .....                                   | 22          |
+
+# Introduction
+
+The development of new digital technologies is now reaching the point at which it is evident that they enable digital systems to offer significant advantages, in comparison with conventional analogue techniques, in terms of vision and sound quality, spectrum and power efficiency, service flexibility, multimedia convergence and potentially lower equipment costs. Moreover, the use of SMATV distribution for the delivery of video and audio signals to individual viewers and listeners is continually growing, and has already become a significant form of distribution in some parts of the world. It is also evident that these potential benefits can best be achieved through the economies of scale resulting from the widespread adoption of digital systems designed to be easily implementable on existing infrastructure and to take advantage of the many possible synergies with related audiovisual systems.
+
+Common features of SMATV networks are the use of consumer-type equipment and the lack of regular maintenance, and therefore the system ruggedness is a primary consideration. In particular, the SMATV head-end should be transparent to the digital TV multiplex, without any baseband interfacing, thus permitting the use of simple and cost-effective consumer-type head-end equipment.
+
+This Recommendation has four Annexes (A, B, C and D) that provide the specifications for the digital SMATV systems submitted to the ITU-T. This reflects the fact that standardization of digital SMATV systems is being addressed for the first time by ITU-T and that a number of systems had been developed and provisionally implemented when this standardization effort was undertaken by the ITU.
+
+Administrations and private operators planning the introduction of SMATV systems are encouraged to consider the use of one of the systems described in Annexes A, B, C and D and to seek opportunities for further convergence, rather than developing a different system based on the same technologies.
+
+This second version of this Recommendation incorporates Amendment 1 and Amendment 2. These amendments brought the following changes with respect to the first edition of this Recommendation:
+
+- a) Annex C has now full text. In the first edition it was stated that Annex C was under study.
+- b) Annex D takes into account additional VSB modes which are specified in the second edition of ITU-T J.83.
+- c) A new Table 1/J.84 is added to show the comparison of the digital multi-programme SMATV systems.
+
+# **Distribution of digital multi-programme signals for television, sound and data services through SMATV networks**
+
+# 1 Scope
+
+The scope of this Recommendation is the definition of the framing structure, channel coding and modulation for digital multi-programme signals distributed by SMATV networks, possibly in frequency-division multiplex with existing analogue television signals.
+
+NOTE – It should be noted that requirements for some ancillary data capacity in the forward channel, related to the needs of interactive services, can be accommodated in the MPEG-2 transport layer, which is specified for all the systems described in the annexes to this Recommendation (a description of the provision and characteristics of the return channel is outside the scope of this Recommendation).
+
+It should also be noted that the specified MPEG-2 transport layer allows the delivery of a number of digital sound channels, at various possible levels of quality; the content of those channels can be either related or unrelated to the video signal content.
+
+This Recommendation is intended to ensure that the designers and installers of SMATV networks carrying digital multi-programme signals will have the information they need to be able to establish and maintain fully satisfactory networks. It also provides the information needed by the designers and manufacturers of equipment (including receivers) for digital multi-programme signals distributed by SMATV networks.
+
+It is to be noted that this Recommendation is complementary to other Recommendations which define the transmission characteristics for digital multi-programme signals distributed by satellite and cable networks (see References).
+
+# 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 J.83 (1997), *Digital multi-programme systems for television, sound and data services for cable distribution*.
+- [2] ITU-R BO.1211 (1995), *Digital multi-programme emission systems for television, sound and data services for satellites operating in the 11/12 GHz frequency range*.
+- [3] ITU-T H.222.0 (2000) | ISO/IEC 13818-1:2000, *Information technology – Generic coding of moving pictures and associated audio information: Systems*.
+- [4] FORNEY (G.D.): Burst-correcting codes for the classic bursty channel, *IEEE Trans. Comm. Tech.*, COM-19, pp. 772-781, October 1971.
+- [5] ITU-R BO.1294 (1997), *Common functional requirements for the reception of digital multi-programme television emissions by satellites operating in the 11/12 GHz frequency range*.
+- [6] ITU-R BO.1408 (1999), *Transmission system for advanced multimedia services provided by integrated services digital broadcasting in a broadcasting-satellite channel*.
+
+# 3 Definitions
+
+This Recommendation defines the following term.
+
+**3.1 satellite master antenna television (SMATV) network:** A broadband network intended for the distribution of television, sound and data signals received directly from one or more satellites, possibly in frequency-division multiplex with similar terrestrial UHF or VHF signals, to households located in one or more adjacent buildings. Where intended also for the distribution of new digital multi-programme television, sound and data services, such networks are known as "Digital SMATV networks", and the digital configuration made for this purpose is known as a "Digital multi-programme SMATV system".
+
+# 4 Symbols and abbreviations
+
+## 4.1 Symbols
+
+This Recommendation uses the following symbols:
+
+|          |                                                                                      |
+|----------|--------------------------------------------------------------------------------------|
+| $\alpha$ | Roll-off factor                                                                      |
+| $f_0$    | Channel centre frequency                                                             |
+| $R_s$    | Symbol rate corresponding to the bilateral Nyquist bandwidth of the modulated signal |
+| $R_u$    | Useful bit rate after MPEG-2 transport multiplexer                                   |
+| $R_{u'}$ | Bit rate after RS outer coder                                                        |
+| $T$      | Number of bytes which can be corrected in RS error protected packet                  |
+| $T_s$    | Symbol period                                                                        |
+
+## 4.2 Abbreviations
+
+This Recommendation uses the following abbreviations:
+
+|      |                                     |
+|------|-------------------------------------|
+| BB   | BaseBand                            |
+| BER  | Bit Error Ratio                     |
+| BPSK | Binary Phase Shift Keying           |
+| BW   | BandWidth                           |
+| DTVC | Digital Television by Cable         |
+| EBU  | European Broadcasting Union         |
+| ETS  | European Telecommunication Standard |
+| FEC  | Forward Error Correction            |
+| FIR  | Finite Impulse Response             |
+| IF   | Intermediate Frequency              |
+| IRD  | Integrated Receiver Decoder         |
+| LNB  | Low Noise Block                     |
+| LSB  | Least Significant Bit               |
+| MPEG | Motion Picture Experts Group        |
+| MSB  | Most Significant Bit                |
+
+|           |                                                           |
+|-----------|-----------------------------------------------------------|
+| MUX       | Multiplex                                                 |
+| PDH       | Plesiochronous Digital Hierarchy                          |
+| PRBS      | PseudoRandom Binary Sequence                              |
+| PSK       | Phase Shift Keying                                        |
+| QAM       | Quadrature Amplitude Modulation                           |
+| QEF       | Quasi Error Free                                          |
+| QPSK      | Quaternary Phase Shift Keying                             |
+| RF        | Radio Frequency                                           |
+| RS        | Reed-Solomon                                              |
+| SMATV     | Satellite Master Antenna Television                       |
+| SMATV-DTM | SMATV system based on Digital TransModulation             |
+| SMATV-IF  | SMATV system based on distribution at IF                  |
+| SMATV-S   | SMATV system based on distribution at extended Super Band |
+| TDL       | Tapped Delay Line                                         |
+| TDM       | Time Division Multiplex                                   |
+| TDT       | Transparent Digital Transmodulator                        |
+| TV        | Television                                                |
+| UHF       | Ultra High Frequency                                      |
+| VHF       | Very High Frequency                                       |
+| VSB       | Vestigial SideBand                                        |
+
+## 5 Digital multi-programme SMATV systems
+
+It is recommended that those wishing to distribute new digital multi-programme services on existing and future SMATV networks should use one of the systems whose framing structure, channel coding and modulation are specified in Annexes A, B, C and D. The specifications are compared in Table 1, indicating common features.
+
+**Table 1/J.84 – Comparison of digital multi-programme SMATV systems**
+
+| Item                                             | Annex A                                                                                          | Annex C                                                       | Annex D                                                        |
+|--------------------------------------------------|--------------------------------------------------------------------------------------------------|---------------------------------------------------------------|----------------------------------------------------------------|
+| Satellite modulation                             | QPSK                                                                                             | BPSK QPSK 8PSK                                                | QPSK                                                           |
+| QPSK distribution excluding frequency conversion | Yes<br>System A2 (SMATV-IF)                                                                      | Yes<br>System C(I)                                            | Not considered                                                 |
+| QPSK distribution including frequency conversion | Yes<br>System A2 (SMATV-IF)                                                                      | Yes<br>System C(II)                                           | Not considered                                                 |
+|                                                  | Yes<br>System A2 (SMATV-S)<br>(VHF/UHF typical 230-470 MHz)                                      |                                                               |                                                                |
+| Transmodulation at the head-end                  | QPSK to QAM<br>(System A1)                                                                       | BPSK, QPSK, or 8PSK<br>to QAM<br>[System C(III)]              | QPSK, 2-VSB, 4-VSB,<br>8-VSB, 16-VSB, 8-VSB<br>(trellis coded) |
+| Simplified implementation of TDT                 | Yes<br>(simplified System A1)                                                                    | Yes                                                           | Not applicable                                                 |
+| Baseband processing at the head-end              | No                                                                                               | No                                                            | Yes<br>(possible reconfiguration of MPEG-2 TS)                 |
+| Receiver (IRD)                                   | QPSK for Systems A2<br>BPSK, QPSK, 8PSK for Systems C(I), C(II)<br>QAM for Systems A1 and C(III) |                                                               | 2-VSB, 4-VSB, 8-VSB,<br>16-VSB, 8-VSB<br>(trellis coded)       |
+| MPEG-2 transport layer                           | Yes                                                                                              | Yes                                                           | Yes                                                            |
+| Compatibility with cable systems (ITU-T J.83)    | Annex A                                                                                          | Annex C                                                       | Annex D                                                        |
+| Channel model                                    | As indicated in Appendix A.I (Annex A)                                                           | Not provided                                                  | Not provided                                                   |
+| Equalization requirements                        | Not necessary for QPSK<br>Simple equalizer for 64-QAM                                            | Not identified                                                | Not identified                                                 |
+| SMATV channel bandwidth                          | Not constrained                                                                                  | Systems C(I), C(II): not constrained:<br>System C(III): 6 MHz | 6 MHz                                                          |
+
+## ANNEX A
+
+## Digital multi-programme SMATV System A
+
+### A.1 Scope
+
+This annex describes a transmission system, known as System A for digital multi-programme television suitable for distribution in Satellite Master Antenna Television (SMATV) systems. This annex describes the SMATV network architecture, is complementary to Annex A/J.83 [1] and it is aligned with [2]. System A described in this annex is compatible with the modulation and channel coding systems used for digital multi-programme television by cable and satellite transmissions (see [1] and [2], respectively). System A is based on the MPEG-2 System Layer [3], with the addition of appropriate Forward Error Correction (FEC) technique. System A allows for further evolution as technology advances as described in [1] (see also the Bibliography in Appendix A.IV to this annex) and is capable of starting a reliable service as of now.
+
+### A.2 References
+
+This annex incorporates by dated and undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed in clause 2 as References [1] to [4].
+
+### A.3 SMATV distribution system concepts
+
+A Satellite Master Antenna Television (SMATV) system is defined as a system which is intended for the distribution of television and sound signals to households located in one or more adjacent buildings. These signals are received by a satellite receiving antenna and may be combined with terrestrial TV signals. SMATV distribution systems are also known as community antenna installations or domestic TV cable networks. A SMATV system represents a means for sharing the same resources among several users for satellite and terrestrial reception.
+
+The SMATV System is designed to perform the adaptation of the satellite TV signals to the SMATV channel characteristics. The primary consideration of the SMATV System is the transparency of the SMATV head-end to the digital TV multiplex from a satellite reception without baseband interfacing, delivering that signal to the user home Integrated Receiver Decoder (IRD); thus permitting a simple and cost effective head-end as required for the consumer profile of SMATV equipment.
+
+This annex considers two main SMATV System approaches for distribution of digital TV signals in SMATV installations, as follows:
+
+**SMATV System A1:** This System approach consists of the transmodulation from satellite Quaternary Phase Shift Keying (QPSK) signals as defined in [2] to a Quadrature Amplitude Modulation (QAM) scheme (16-QAM, 32-QAM or 64-QAM) using either a full implementation of the System described in Annex A/J.83 [1] (see A.4.1 below), or a simplified transmodulation process as described in A.4.2 below. This process of transmodulation without baseband interfacing is also known as Transparent Transmodulation.
+
+**SMATV System A2:** Direct distribution of QPSK satellite signals as defined in [2] using frequency conversion of the received satellite signal to a frequency band appropriate to the characteristics of the distribution network.
+
+The use of one of the System A1 or System A2 approaches depends on the technical performance and cost trade-offs in each particular situation.
+
+NOTE – Digital terrestrial specification is not the subject of this annex.
+
+### A.4 SMATV System A1
+
+SMATV System A1 is based on the use of the transmodulation from satellite QPSK signals to a QAM modulation scheme (see Figure A.1). This system is also known as SMATV-DTM.
+
+The System comprises the following elements:
+
+- **Head-end transmodulation unit:** This performs the required decoding and adapts the signal modulation coding to the cable distribution network. This unit is also known as the Transparent Digital Transmodulator (TDT).
+- **SMATV UHF distribution network:** This is a physical cable structure for distribution of the signal to several users. The reference channel response of SMATV distribution network is given in Appendix A.I.
+- **User IRD:** This unit performs the required equalization to compensate the channel distortion as well as demodulating and decoding the QAM signal.
+
+#### A.4.1 Full implementation of SMATV System A1
+
+A full implementation of the QAM System shall be performed according to Annex A/J.83 [1] and to [2] with a transparent interface between them. To this end, the full implementation of SMATV System A1 shall make use of the MPEG-2 transport layer, the framing structure, the channel coding, the byte-to-symbol mapping and modulation consistent with Annex A/J.83 [1] and with [2]. The channel coding shall include the randomization for spectrum shaping, the Reed-Solomon (RS) coding and the convolutional interleaving according to Forney [4]. This configuration is shown in Figure A.2.
+
+#### A.4.2 Simplified implementation of SMATV System A1
+
+In the complete implementation architecture of SMATV System A1, outer error protection (i.e. Reed-Solomon and convolutional interleaving) is performed twice, i.e. independently for the satellite link and the cable link. Therefore, the cable link is fed by a Quasi Error Free (QEF) bit stream. In cases when an adequate satellite link margin is achieved, one Reed-Solomon decoder-encoder and de-interleaving-interleaving process could be eliminated from the System. In such cases, a single RS decoder at the user IRD is capable of correcting errors generated in the cable link added to the remaining bursty errors after Viterbi decoding. This configuration is shown in Figure A.2 when removing the dashed line blocks.
+
+NOTE – This simplified configuration may imply a non-negligible saving in terms of the number of gates and thus in the total equipment cost. Due to consumer type character of SMATV head-ends, this saving is important when an economy of scale is achieved. Consequently, manufacturers could decide whether to adopt the simplified SMATV System A1 architecture.
+
+### A.5 SMATV System A2
+
+SMATV System A2 is based on the use of QPSK modulation (see Figure A.3). The SMATV System A2 concept allows a direct reception of digital satellite signals by the user IRD connected to a SMATV distribution network. The functional elements of this system are given in [2]. Two configurations of SMATV System A2 are considered as follows:
+
+- SMATV-IF;
+- SMATV-S.
+
+In the SMATV-IF configuration, QPSK signals are distributed directly at the Intermediate Frequency (IF) as delivered by the Low Noise Block (LNB) [see Figure A.3 a)]. In the SMATV-S configuration, QPSK signals are frequency converted to S-band [see Figure A.3 b)]. In both configurations, the satellite signal reaches the user IRD without being subject to any demodulation and transmodulation process at the head-end. Thus, the modulation characteristics of the satellite link are retained.
+
+![Figure A.1/J.84 – SMATV System A1 configuration. This diagram shows the overall system architecture. A satellite dish receives a QPSK signal from a satellite. The signal is sent to an IF (Intermediate Frequency) block, which then connects to a TDT (Transport Data Transport) block. The TDT block outputs a QAM signal. This QAM signal is then split into three UHF (Ultra High Frequency) distribution lines, each connected to a user IRD (Interactive Receiver Device). The user IRD is connected to a television set. The entire setup is labeled 'SMATV UHF distribution network'.](4801720824e4b5e2361a5564f91cfb70_img.jpg)
+
+Figure A.1/J.84 – SMATV System A1 configuration. This diagram shows the overall system architecture. A satellite dish receives a QPSK signal from a satellite. The signal is sent to an IF (Intermediate Frequency) block, which then connects to a TDT (Transport Data Transport) block. The TDT block outputs a QAM signal. This QAM signal is then split into three UHF (Ultra High Frequency) distribution lines, each connected to a user IRD (Interactive Receiver Device). The user IRD is connected to a television set. The entire setup is labeled 'SMATV UHF distribution network'.
+
+Figure A.1/J.84 – SMATV System A1 configuration
+
+![Figure A.2/J.84 – Functional diagram of a SMATV System A1. This diagram details the internal functional blocks of the system. The input is 'From IF satellite channel'. The signal passes through an 'IF physical interface QPSK demodulator', then a 'Matched filter', and a 'Depuncturing Viterbi decoder'. The output of the Viterbi decoder is split into 'Q' (Quadrature) and 'I' (In-phase) components. These components are processed by a 'Sync demodulator', which also receives input from a 'Carrier & clock recovery' block. The signal then enters a series of blocks: 'Convolutional deinterleaver l = 12', 'RS decoder (204, 188) (T = 8)', 'RS encoder (204, 188) (T = 8)', and 'Convolutional interleaver l = 12'. These four blocks are grouped together in a dashed box. The output of the interleaver goes to 'Byte to m-tuple convolution', then 'Differential encoder', and finally 'QAM modulator & UHF physical interface', which outputs 'To UHF SMATV channel'. A 'Clock & sync generator Code Rate Control' block provides timing and control signals to the 'Carrier & clock recovery', 'Sync demodulator', and the four blocks in the dashed box. The diagram is labeled 'T0902920-95'.](4ee27dbf5ef12e7b58b0ef0937bc5a5e_img.jpg)
+
+Figure A.2/J.84 – Functional diagram of a SMATV System A1. This diagram details the internal functional blocks of the system. The input is 'From IF satellite channel'. The signal passes through an 'IF physical interface QPSK demodulator', then a 'Matched filter', and a 'Depuncturing Viterbi decoder'. The output of the Viterbi decoder is split into 'Q' (Quadrature) and 'I' (In-phase) components. These components are processed by a 'Sync demodulator', which also receives input from a 'Carrier & clock recovery' block. The signal then enters a series of blocks: 'Convolutional deinterleaver l = 12', 'RS decoder (204, 188) (T = 8)', 'RS encoder (204, 188) (T = 8)', and 'Convolutional interleaver l = 12'. These four blocks are grouped together in a dashed box. The output of the interleaver goes to 'Byte to m-tuple convolution', then 'Differential encoder', and finally 'QAM modulator & UHF physical interface', which outputs 'To UHF SMATV channel'. A 'Clock & sync generator Code Rate Control' block provides timing and control signals to the 'Carrier & clock recovery', 'Sync demodulator', and the four blocks in the dashed box. The diagram is labeled 'T0902920-95'.
+
+Figure A.2/J.84 – Functional diagram of a SMATV System A1
+
+![Figure A.3/J.84 – SMATV System A2 configuration, SMATV-IF and SMATV-S. The diagram shows two configurations: a) SMATV-IF and b) SMATV-S. Both start with a satellite transmitting a QPSK signal to a ground station. In configuration (a), the ground station outputs an IF signal to a block labeled 'SMATV distribution network' (with 'QPSK-IF' above it). The output of this block is an IF signal connected to a 'QPSK IRD' block. In configuration (b), the ground station outputs an IF signal to an 'FC' block labeled 'IF → S'. The output of this block is an 'S' signal connected to a block labeled 'SMATV distribution network' (with 'QPSK S-band' above it). The output of this block is an 'S' signal connected to another 'FC' block labeled 'S → IF'. The output of this block is an IF signal connected to a 'QPSK IRD' block. A small text 'T0902930-95' is present below the second configuration.](33ed1f9b27c7c21c797aa928b0f06851_img.jpg)
+
+Figure A.3/J.84 – SMATV System A2 configuration, SMATV-IF and SMATV-S. The diagram shows two configurations: a) SMATV-IF and b) SMATV-S. Both start with a satellite transmitting a QPSK signal to a ground station. In configuration (a), the ground station outputs an IF signal to a block labeled 'SMATV distribution network' (with 'QPSK-IF' above it). The output of this block is an IF signal connected to a 'QPSK IRD' block. In configuration (b), the ground station outputs an IF signal to an 'FC' block labeled 'IF → S'. The output of this block is an 'S' signal connected to a block labeled 'SMATV distribution network' (with 'QPSK S-band' above it). The output of this block is an 'S' signal connected to another 'FC' block labeled 'S → IF'. The output of this block is an IF signal connected to a 'QPSK IRD' block. A small text 'T0902930-95' is present below the second configuration.
+
+**Figure A.3/J.84 – SMATV System A2 configuration, SMATV-IF and SMATV-S**
+
+#### A.5.1 SMATV-IF
+
+This configuration allows the direct distribution of the QPSK signal received from the satellite to the SMATV-IF distribution network in the extended IF band (above 950 MHz).
+
+The user IRD should be able to tune all the channels in the extended IF band to demodulate and to decode the signal.
+
+The functional elements of SMATV-IF are given in [2].
+
+#### A.5.2 SMATV-S
+
+This configuration requires the frequency conversion of the satellite signals from extended IF band (above 950 MHz) to a part of the VHF/UHF band [for example: extended S-band (230 MHz to 470 MHz)].
+
+NOTE – An inverse frequency conversion process (e.g. from extended S-band to IF) may be required at user IRD equipped with IF tuner.
+
+The user IRD performs similar functions as for the satellite reception (see [2]). In order to compensate for the channel linear distortions, the matched filter may include equalization capabilities.
+
+The S-band channel model is similar to that of the UHF band; it is given in Appendix A.I.
+
+### **A.6 MPEG-2 transport layer**
+
+The SMATV System shall use the MPEG-2 transport layer which is defined in [3]. The Transport Layer for MPEG-2 data is comprised of packets having 188 bytes, with one byte for synchronization purposes, three bytes of header containing service identification, scrambling and control information, followed by 184 bytes of MPEG-2 or auxiliary data.
+
+### **A.7 Framing structure**
+
+The framing organization of the SMATV System shall be based on the MPEG-2 transport packet structure (see [1], [2] and [3]).
+
+## **APPENDIX A.I**
+
+### **Channel model of SMATV distribution systems**
+
+(to Annex A of Recommendation J.84)
+
+#### **A.I.1 Channel model response**
+
+In order to test SMATV Systems and to evaluate the need for equalization, an RF channel model response has been obtained for SMATV distribution network. The model is based on measurements and computer simulations. The model is significantly simplified in order to take into account only the relevant aspects for the equalization definition. It applies to UHF band as well as S-band SMATV networks.
+
+The RF channel model is split into four models; they are presented in Figures A.I.1 to A.I.4:
+
+- model A: for microreflections between devices in consecutive floors (Figure A.I.1);
+- model B: for microreflections between head-end and first device (Figure A.I.2);
+- model C: for microreflections between tap-off and user outlet (Figure A.I.3);
+- model D: combined microreflections model (Figure A.I.4).
+
+Real SMATV networks usually combine features from all models depending on the concrete structure, and mainly the cable length and mismatching degree in each connection. It has been concluded that:
+
+- microreflections delay depends on cable lengths;
+- microreflections attenuation depends on the level of mismatching among components (return losses).
+
+These models are based on assumptions derived from a survey on the most extended SMATV structures, see [5] in Appendix A.IV. The following configuration has been considered as a reference:
+
+- a range of 3 m to 3.5 m cable length between cascade user outlets;
+- a range of 6 m to 12 m cable length between tap-off and user outlet for parallel structures;
+- a range of 10 m to 20 m cable length between head-end amplifiers and first passive elements;
+- approximately a 10-storey building, in order to include representative echoes generated in several floors.
+
+In Figures A.I.1 to A.I.4 microreflection distribution can be observed for the 4 models. The X-axis in the diagrams represents the microreflection delay in nanoseconds. The Y-axis gives microreflection attenuation in dB. Taking the above considerations into account, the echo delay ranges can be noted.
+
+The reference channel model for most practical installations is given in Figures A.I.1 to A.I.4 marked with "3 sigma" and is represented in dark colour. The upper level refers to the worst case.
+
+#### A.I.2 Definition of adaptive equalization requirements
+
+QAM demodulator at the user IRD should include an adaptive equalizer to compensate the channel distortion introduced by SMATV in the UHF band. An equalizer may also be included at the user IRD for QPSK demodulation in the S-band. Equalization should be blind, since the baseline systems do not include any training sequence. Referring to the reference RF channel model of Figures A.I.1 to A.I.4 for the 3 sigma case, state of the art implementations of equalizers can provide less than 1 dB implementation margin at a BER of  $2 \times 10^{-4}$ , and less than 100 ms acquisition time.
+
+![Bar chart showing Relative amplitude (dB) vs Relative delay (ns) for Model A. The chart displays worstcase and 3 sigma values for various delay intervals. The 3 sigma values are generally higher (less negative) than the worstcase values. Black squares indicate specific data points.](f4d72193f77f6646a2a1f4baaa927154_img.jpg)
+
+Model A: Microreflections between devices in consecutive floors
+
+| Relative delay (ns) | Worstcase (dB) | 3 sigma (dB) |
+|---------------------|----------------|--------------|
+| 1-5                 | -40            | -40          |
+| 6-10                | -40            | -40          |
+| 11-15               | -40            | -40          |
+| 16-20               | -40            | -40          |
+| 21-25               | -40            | -40          |
+| 26-30               | -10            | -12          |
+| 31-35               | -40            | -40          |
+| 36-40               | -40            | -40          |
+| 41-45               | -40            | -40          |
+| 46-50               | -40            | -40          |
+| 51-55               | -12            | -15          |
+| 56-60               | -12            | -15          |
+| 61-65               | -40            | -40          |
+| 66-70               | -40            | -40          |
+| 71-75               | -40            | -40          |
+| 76-80               | -15            | -20          |
+| 81-85               | -15            | -20          |
+| 86-90               | -40            | -40          |
+| 91-95               | -40            | -40          |
+| 96-100              | -40            | -40          |
+| 101-105             | -20            | -25          |
+| 106-110             | -20            | -25          |
+| 111-115             | -20            | -25          |
+| 116-120             | -20            | -25          |
+| 121-125             | -20            | -25          |
+| 126-130             | -25            | -30          |
+| 131-135             | -25            | -30          |
+| 136-140             | -25            | -30          |
+| 141-145             | -25            | -30          |
+| 146-150             | -25            | -30          |
+| 151-155             | -25            | -30          |
+| 156-160             | -25            | -30          |
+| 161-165             | -25            | -30          |
+| 166-170             | -25            | -30          |
+| 171-175             | -25            | -30          |
+| 176-180             | -25            | -30          |
+| 181-185             | -25            | -30          |
+| 186-190             | -25            | -30          |
+| 191-195             | -25            | -30          |
+| 196-200             | -25            | -30          |
+| 201-205             | -25            | -30          |
+| 206-210             | -25            | -30          |
+| 211-215             | -25            | -30          |
+| 216-220             | -25            | -30          |
+| 221-225             | -25            | -30          |
+| 226-230             | -25            | -30          |
+| 231-235             | -25            | -30          |
+| 236-240             | -25            | -30          |
+| 241-245             | -25            | -30          |
+
+T0902940-95
+
+Bar chart showing Relative amplitude (dB) vs Relative delay (ns) for Model A. The chart displays worstcase and 3 sigma values for various delay intervals. The 3 sigma values are generally higher (less negative) than the worstcase values. Black squares indicate specific data points.
+
+**Figure A.I.1/J.84 – RF channel model A response of UHF and S-bands SMATV distribution network**
+
+![Bar chart showing Relative amplitude (dB) vs Relative delay (ns) for Model B. The chart displays worstcase and 3 sigma values for various delay intervals. The 3 sigma values are generally higher (less negative) than the worstcase values. Black squares indicate specific data points.](fdcfba1180dc160c7d539c5fb2a6c1e6_img.jpg)
+
+Model B: Microreflections between head-end and first device
+
+| Relative delay (ns) | Worstcase (dB) | 3 sigma (dB) |
+|---------------------|----------------|--------------|
+| 1-5                 | -40            | -40          |
+| 6-10                | -40            | -40          |
+| 11-15               | -40            | -40          |
+| 16-20               | -40            | -40          |
+| 21-25               | -40            | -40          |
+| 26-30               | -40            | -40          |
+| 31-35               | -40            | -40          |
+| 36-40               | -40            | -40          |
+| 41-45               | -40            | -40          |
+| 46-50               | -40            | -40          |
+| 51-55               | -40            | -40          |
+| 56-60               | -40            | -40          |
+| 61-65               | -40            | -40          |
+| 66-70               | -40            | -40          |
+| 71-75               | -40            | -40          |
+| 76-80               | -40            | -40          |
+| 81-85               | -40            | -40          |
+| 86-90               | -40            | -40          |
+| 91-95               | -40            | -40          |
+| 96-100              | -40            | -40          |
+| 101-105             | -15            | -20          |
+| 106-110             | -15            | -20          |
+| 111-115             | -15            | -20          |
+| 116-120             | -15            | -20          |
+| 121-125             | -15            | -20          |
+| 126-130             | -15            | -20          |
+| 131-135             | -15            | -20          |
+| 136-140             | -15            | -20          |
+| 141-145             | -15            | -20          |
+| 146-150             | -15            | -20          |
+| 151-155             | -15            | -20          |
+| 156-160             | -15            | -20          |
+| 161-165             | -15            | -20          |
+| 166-170             | -15            | -20          |
+| 171-175             | -15            | -20          |
+| 176-180             | -15            | -20          |
+| 181-185             | -15            | -20          |
+| 186-190             | -15            | -20          |
+| 191-195             | -15            | -20          |
+| 196-200             | -15            | -20          |
+| 201-205             | -15            | -20          |
+| 206-210             | -15            | -20          |
+| 211-215             | -15            | -20          |
+| 216-220             | -15            | -20          |
+| 221-225             | -15            | -20          |
+| 226-230             | -15            | -20          |
+| 231-235             | -15            | -20          |
+| 236-240             | -15            | -20          |
+| 241-245             | -15            | -20          |
+
+T0902950-95
+
+Bar chart showing Relative amplitude (dB) vs Relative delay (ns) for Model B. The chart displays worstcase and 3 sigma values for various delay intervals. The 3 sigma values are generally higher (less negative) than the worstcase values. Black squares indicate specific data points.
+
+**Figure A.I.2/J.84 – RF channel model B response of UHF and S-bands SMATV distribution network**
+
+![Figure A.I.3/J.84: RF channel model C response of UHF and S-bands SMATV distribution network. The graph plots Relative amplitude (dB) on the y-axis from 0 to -40 in increments of 5, against Relative delay (ns) on the x-axis in 5 ns bins from 1-5 to 241-245. A light gray shaded region represents 'worstcase' and a dark gray region represents '3 sigma'. The 'worstcase' region starts at -15 dB (46-50 ns) and slopes down to -20 dB (96-100 ns). The '3 sigma' region starts at -20 dB (46-50 ns) and slopes down to -25 dB (96-100 ns). A single black square data point is located at approximately 76-80 ns and -17 dB.](b53846f262c6904a1b45abef2e95fbd8_img.jpg)
+
+Model C: Microreflections between tap-off and user outlet
+
+T0902960-95
+
+    worstcase  
+    3 sigma
+
+Figure A.I.3/J.84: RF channel model C response of UHF and S-bands SMATV distribution network. The graph plots Relative amplitude (dB) on the y-axis from 0 to -40 in increments of 5, against Relative delay (ns) on the x-axis in 5 ns bins from 1-5 to 241-245. A light gray shaded region represents 'worstcase' and a dark gray region represents '3 sigma'. The 'worstcase' region starts at -15 dB (46-50 ns) and slopes down to -20 dB (96-100 ns). The '3 sigma' region starts at -20 dB (46-50 ns) and slopes down to -25 dB (96-100 ns). A single black square data point is located at approximately 76-80 ns and -17 dB.
+
+**Figure A.I.3/J.84 – RF channel model C response of UHF and S-bands SMATV distribution network**
+
+![Figure A.I.4/J.84: RF channel model D response of UHF and S-bands SMATV distribution network. The graph plots Relative amplitude (dB) on the y-axis from 0 to -40 against Relative delay (ns) on the x-axis from 1-5 to 241-245. Shaded regions for 'worstcase' (light gray) and '3 sigma' (dark gray) are shown. The 'worstcase' region spans from -15 dB at 46-50 ns to -35 dB at 241-245 ns. The '3 sigma' region spans from -20 dB at 46-50 ns to -40 dB at 241-245 ns. Several black square data points are plotted: (26-30, -8), (51-55, -12), (71-75, -16), (81-85, -16), (101-105, -21), (111-115, -21), (136-140, -24), (166-170, -28), (191-195, -32).](b6750d26d3dd287a4a4d49b3670a44bd_img.jpg)
+
+Model D: Combined model
+
+T0902970-95
+
+    worstcase  
+    3 sigma
+
+Figure A.I.4/J.84: RF channel model D response of UHF and S-bands SMATV distribution network. The graph plots Relative amplitude (dB) on the y-axis from 0 to -40 against Relative delay (ns) on the x-axis from 1-5 to 241-245. Shaded regions for 'worstcase' (light gray) and '3 sigma' (dark gray) are shown. The 'worstcase' region spans from -15 dB at 46-50 ns to -35 dB at 241-245 ns. The '3 sigma' region spans from -20 dB at 46-50 ns to -40 dB at 241-245 ns. Several black square data points are plotted: (26-30, -8), (51-55, -12), (71-75, -16), (81-85, -16), (101-105, -21), (111-115, -21), (136-140, -24), (166-170, -28), (191-195, -32).
+
+**Figure A.I.4/J.84 – RF channel model D response of UHF and S-bands SMATV distribution network**
+
+## APPENDIX A.II
+
+### **Examples of 64-QAM and QPSK performance with equalizers**
+
+(to Annex A of Recommendation J.84)
+
+In the following, performance of two possible examples of SMATV systems are investigated by computer simulations:
+
+**SMATV System A1:** Transmodulation from QPSK to 64-QAM, symbol rate  $R_s = 6.9$  MBaud in 8 MHz channels, useful bit rate of 38 Mbit/s at the MPEG multiplex output.
+
+**SMATV System A2:** QPSK modulation with rate 3/4 convolutional coding, symbol rate  $R_s = 25.8$  MBaud and useful bit rate of 35.6 Mbit/s at the MPEG multiplex output.
+
+To overcome the linear distortions introduced by the SMATV network, an adaptive "blind" equalizer (see [4] in Appendix A.IV), composed by a symbol-spaced complex transversal filter Finite Impulse Response (FIR), has been introduced in the receiver. The second tap of the equalizer was set to "1", since the presence of anticipated echoes can generally be excluded in SMATV installations. The results assume steady state of the equalizer, after the end of the blind lock-in phase.
+
+Some critical examples of SMATV channels have been considered in the simulations, as measured on a hardware-simulated SMATV network for a 5-floor building (see [3] in Appendix A.IV). The channel amplitude and group delay characteristics are reported in Figures A.II.1 to A.II.6. The first case (Response 1) refers to a 40 MHz channel, suitable for System A2, while the others (i.e. Response 2, to, Response 6) refer to 8 MHz channels, suitable for System A1.
+
+#### A.II.1 SMATV System A1 – Simulation results
+
+With System A1 the signal is regenerated at the SMATV network input, therefore the noise generator in the simulations was put at the 64-QAM demodulator input, after the SMATV network. Very high degradation levels have been obtained without equalization. In the presence of adaptive equalization with 6 symbol-spaced taps, the signal-to-noise ratio degradation for BER equal to  $2 \times 10^{-4}$  (before Reed-Solomon correction) was lower than 1.5 dB in all the five analyzed network responses [2] in Appendix A.IV. These results refer to the value of 23.8 dB in a bandwidth of 7 MHz in an ideal linear Gaussian channel; they do not however include possible additional impairments due to amplifier non-linearity in the cable head-end.
+
+It is therefore possible to conclude that with SMATV System A1 (in the 64-QAM configuration), the use of adaptive equalizers is mandatory to overcome typical SMATV network degradations. However, in the case of old cable installations with very poor performance (e.g. echo levels of about 8 dB to 12 dB, as given in Figures A.I.1 to A.I.4), the use of the equalizer might be insufficient to guarantee 100% service availability when 64-QAM modulation is adopted. Nevertheless, in the case of new installations complying with [8] in Appendix A.IV, the service availability with 64-QAM can be guaranteed by a suitable equalizer.
+
+Hardware tests with a 16-QAM modem including blind equalization have demonstrated good performance on the above described SMATV network, see [3] in Appendix A.IV.
+
+As regards the required number of equalization (symbol-spaced) taps  $N$ , the echo delay spread  $T_e$  to be considered on typical SMATV networks is of the order of 220 ns, as indicated in Figures A.I.1 to A.I.4 (64-QAM requires C/I levels of the order of 35 dB). Assuming that the second tap of the equalizer is set to "1", to achieve good performance with 64-QAM and high echo levels,  $N$  should be larger than  $2 + 2 T_e/T_s$ . Therefore, for a symbol duration  $T_s = 143$  ns, the minimum equalizer length should be of about 6 taps, while 8 to 10 taps could offer an additional margin to cope with longer echoes.
+
+#### A.II.2 SMATV System A.2 – Simulation results
+
+Since in a well-designed SMATV network adopting SMATV System A2 the main noise source should be in the satellite downlink path, the noise source in the simulations has been put before the SMATV network. The SMATV network transfer function, which has been used in the simulations, is "Response 1" of Figure A.II.1.
+
+For BER equal to  $10^{-4}$  before Reed-Solomon correction, the SMATV network introduced a degradation on the required C/N (calculated in a bandwidth of 26.8 MHz) for the satellite of about 1.4 dB on the system without equalizer, while the degradation was reduced to 0.4 dB with the equalizer [2] in Appendix A.IV. These results refer to the value of 6.1 dB in an ideal linear Gaussian channel; no implementation margin is included. Therefore also for SMATV System A2, based on the
+
+rugged QPSK modulation, the use of an adaptive equalizer in the receiver seems important, allowing to utilize current SMATV installations with very low additional C/N degradation with respect to direct satellite reception.
+
+Hardware tests with a QPSK modulator including rate 3/4 convolutional coding, without equalizer, confirmed the simulation results on the above SMATV network.
+
+As regards the number of equalizer (symbol-spaced) taps  $N$ , assuming that the second tap of the equalizer is set to "1", good QPSK performance can be achieved for  $N > 2 + (T_e/T_s)$ , where  $T_e$  is the echo delay spread to be considered. For  $T_e = 220$  ns, as indicated in Figure A.I.1, and a symbol duration of  $T_s = 30$  ns, the minimum equalizer length should be of about 10 taps.
+
+![Figure A.II.1/J.84: Significant example of the measured transfer function for the considered SMATV network. The graph shows amplitude and group delay versus frequency offset f - f0 (MHz).](9260ae281f6b6470331f4a0f82dbc2b1_img.jpg)
+
+The graph, titled "Response 1", plots two metrics against the frequency offset  $f - f_0$  (MHz) ranging from -20 to 20. The left y-axis represents amplitude in dB, ranging from -8 to 0. The right y-axis represents group delay in ns, ranging from -14 to 2. The amplitude is shown as a solid line with square markers, and the group delay is shown as a solid line with open square markers. The amplitude curve shows significant fluctuations, with a major peak near 0 MHz and several deep nulls, notably around -15 MHz and -5 MHz. The group delay curve also exhibits significant variations, with a sharp drop around -15 MHz and a peak near 0 MHz.
+
+| $f - f_0$ (MHz) | Amplitude (dB) | Group Delay (ns) |
+|-----------------|----------------|------------------|
+| -20             | -0.5           | 0.5              |
+| -15             | -6.5           | -6.5             |
+| -10             | -2.5           | -3.5             |
+| -5              | -5.5           | -2.5             |
+| 0               | -0.5           | 0.5              |
+| 5               | -7.5           | -5.5             |
+| 10              | -3.5           | -3.5             |
+| 15              | -4.5           | -4.5             |
+| 20              | -7.5           | -12.5            |
+
+Figure A.II.1/J.84: Significant example of the measured transfer function for the considered SMATV network. The graph shows amplitude and group delay versus frequency offset f - f0 (MHz).
+
+**Figure A.II.1/J.84 – Significant example of the measured transfer function for the considered SMATV network**
+
+![Graph titled 'Response 2' showing amplitude and group delay versus frequency offset f - f0 (MHz). The amplitude curve (solid line with squares) starts at -2.4 dB at -4 MHz, dips to -3.6 dB at 0 MHz, and rises to -1.6 dB at 4 MHz. The group delay curve (dashed line with squares) starts at 14 ns at -4 MHz, dips to -5 ns at 0 MHz, and rises to 34 ns at 4 MHz.](5ed9189841659dfb01f809b8e3b21f74_img.jpg)
+
+Response 2
+
+0
+
+-1
+
+-2
+
+-3
+
+-4
+
+35
+
+30
+
+25
+
+20
+
+15
+
+10
+
+5
+
+0
+
+-5
+
+-4 -3 -2 -1 0 1 2 3 4
+
+$f - f_0$  (MHz)
+
+T0902990-95
+
+■ amplitude
+
+□ group delay
+
+Graph titled 'Response 2' showing amplitude and group delay versus frequency offset f - f0 (MHz). The amplitude curve (solid line with squares) starts at -2.4 dB at -4 MHz, dips to -3.6 dB at 0 MHz, and rises to -1.6 dB at 4 MHz. The group delay curve (dashed line with squares) starts at 14 ns at -4 MHz, dips to -5 ns at 0 MHz, and rises to 34 ns at 4 MHz.
+
+**Figure A.II.2/J.84 – Significant example of the measured transfer function for the considered SMATV network**
+
+![Graph titled 'Response 3' showing amplitude and group delay versus frequency offset f - f0 (MHz). The amplitude curve (solid line with squares) starts at -3.3 dB at -4 MHz, rises to -0.9 dB at -1 MHz, and then declines to -2.3 dB at 4 MHz. The group delay curve (dashed line with squares) starts at -24 ns at -4 MHz, rises to 14 ns at 0.5 MHz, and then declines to 5 ns at 4 MHz.](2a77eb32ef4c4d8a5c1758a53a908336_img.jpg)
+
+Response 3
+
+0
+
+-1
+
+-2
+
+-3
+
+-4
+
+15
+
+10
+
+5
+
+0
+
+-5
+
+-10
+
+-15
+
+-20
+
+-25
+
+-4 -3 -2 -1 0 1 2 3 4
+
+$f - f_0$  (MHz)
+
+T0903000-95
+
+■ amplitude
+
+□ group delay
+
+Graph titled 'Response 3' showing amplitude and group delay versus frequency offset f - f0 (MHz). The amplitude curve (solid line with squares) starts at -3.3 dB at -4 MHz, rises to -0.9 dB at -1 MHz, and then declines to -2.3 dB at 4 MHz. The group delay curve (dashed line with squares) starts at -24 ns at -4 MHz, rises to 14 ns at 0.5 MHz, and then declines to 5 ns at 4 MHz.
+
+**Figure A.II.3/J.84 – Significant example of the measured transfer function for the considered SMATV network**
+
+![Figure A.II.4/J.84: Significant example of the measured transfer function for the considered SMATV network. The graph shows amplitude and group delay versus frequency offset f - f0 (MHz).](60e9207be66a64332619bb4b667fe67b_img.jpg)
+
+Figure A.II.4/J.84 shows the measured transfer function for the considered SMATV network. The graph plots amplitude (solid line with square markers) and group delay (dashed line with square markers) against the frequency offset  $f - f_0$  (MHz). The x-axis ranges from -4 to 4 MHz. The left y-axis for amplitude ranges from -3 to 0, and the right y-axis for group delay ranges from -10 to 50. The amplitude curve peaks at approximately -0.2 at  $f - f_0 = -2.5$  MHz and then decreases, crossing zero at  $f - f_0 = 0$  MHz. The group delay curve peaks at approximately 48 at  $f - f_0 = -2.5$  MHz and then decreases, crossing zero at  $f - f_0 = 0$  MHz.
+
+| $f - f_0$ (MHz) | Amplitude | Group Delay |
+|-----------------|-----------|-------------|
+| -4              | -2.8      | 5           |
+| -3              | -1.8      | 30          |
+| -2.5            | -0.2      | 48          |
+| -2              | -0.5      | 45          |
+| -1.5            | -2.0      | 25          |
+| -1              | -2.5      | 15          |
+| -0.5            | -2.6      | 10          |
+| 0               | -2.5      | 0           |
+| 0.5             | -2.4      | -5          |
+| 1               | -2.3      | -8          |
+| 1.5             | -2.2      | -10         |
+| 2               | -2.1      | -12         |
+| 2.5             | -2.0      | -14         |
+| 3               | -1.9      | -16         |
+| 3.5             | -1.8      | -18         |
+| 4               | -1.7      | -20         |
+
+Figure A.II.4/J.84: Significant example of the measured transfer function for the considered SMATV network. The graph shows amplitude and group delay versus frequency offset f - f0 (MHz).
+
+**Figure A.II.4/J.84 – Significant example of the measured transfer function for the considered SMATV network**
+
+![Figure A.II.5/J.84: Significant example of the measured transfer function for the considered SMATV network. The graph shows amplitude and group delay versus frequency offset f - f0 (MHz).](9a19da4f7fccb96a934411c0bb5a386d_img.jpg)
+
+Figure A.II.5/J.84 shows the measured transfer function for the considered SMATV network. The graph plots amplitude (solid line with square markers) and group delay (dashed line with square markers) against the frequency offset  $f - f_0$  (MHz). The x-axis ranges from -4 to 4 MHz. The left y-axis for amplitude ranges from -7 to 0, and the right y-axis for group delay ranges from -45 to 25. The amplitude curve starts at approximately -0.8 at  $f - f_0 = -4$  MHz and decreases steadily, reaching approximately -5.5 at  $f - f_0 = 4$  MHz. The group delay curve starts at approximately 22 at  $f - f_0 = -4$  MHz and decreases steadily, reaching approximately -35 at  $f - f_0 = 4$  MHz.
+
+| $f - f_0$ (MHz) | Amplitude | Group Delay |
+|-----------------|-----------|-------------|
+| -4              | -0.8      | 22          |
+| -3              | -0.6      | 20          |
+| -2              | -1.1      | 15          |
+| -1              | -1.7      | 10          |
+| -0.5            | -2.0      | 8           |
+| 0               | -2.5      | 0           |
+| 0.5             | -3.2      | -5          |
+| 1               | -4.2      | -15         |
+| 1.5             | -5.0      | -25         |
+| 2               | -5.3      | -30         |
+| 2.5             | -5.5      | -35         |
+| 3               | -5.4      | -38         |
+| 3.5             | -5.2      | -38         |
+| 4               | -4.9      | -35         |
+
+Figure A.II.5/J.84: Significant example of the measured transfer function for the considered SMATV network. The graph shows amplitude and group delay versus frequency offset f - f0 (MHz).
+
+**Figure A.II.5/J.84 – Significant example of the measured transfer function for the considered SMATV network**
+
+![Figure A.II.6/J.84: Significant example of the measured transfer function for the considered SMATV network. The graph shows amplitude (solid line with black squares) and group delay (solid line with open squares) versus normalized frequency f - f0 (MHz). The x-axis ranges from -4 to 4 MHz. The left y-axis ranges from -9 to 0, and the right y-axis ranges from -65 to 25. The amplitude curve starts at -8 at -4 MHz and rises to -1 at 4 MHz. The group delay curve starts at -55 at -4 MHz and rises to 25 at 4 MHz.](0f79a59f3766fc341ff688a23692c1d9_img.jpg)
+
+Response 6
+
+| $f - f_0$ (MHz) | Amplitude (dB) | Group Delay (ns) |
+|-----------------|----------------|------------------|
+| -4              | -8.0           | -55              |
+| -3.5            | -7.6           | -50              |
+| -3              | -7.0           | -45              |
+| -2.5            | -6.2           | -38              |
+| -2              | -5.4           | -30              |
+| -1.5            | -4.6           | -20              |
+| -1              | -3.8           | -10              |
+| -0.5            | -3.1           | 0                |
+| 0               | -2.5           | 10               |
+| 0.5             | -2.0           | 15               |
+| 1               | -1.8           | 20               |
+| 1.5             | -1.6           | 23               |
+| 2               | -1.4           | 24               |
+| 2.5             | -1.2           | 24.5             |
+| 3               | -1.1           | 25               |
+| 3.5             | -0.9           | 25               |
+| 4               | -1.0           | 25               |
+
+■ amplitude  
+□ group delay
+
+T0903030-95
+
+Figure A.II.6/J.84: Significant example of the measured transfer function for the considered SMATV network. The graph shows amplitude (solid line with black squares) and group delay (solid line with open squares) versus normalized frequency f - f0 (MHz). The x-axis ranges from -4 to 4 MHz. The left y-axis ranges from -9 to 0, and the right y-axis ranges from -65 to 25. The amplitude curve starts at -8 at -4 MHz and rises to -1 at 4 MHz. The group delay curve starts at -55 at -4 MHz and rises to 25 at 4 MHz.
+
+**Figure A.II.6/J.84 – Significant example of the measured transfer function  
+for the considered SMATV network**
+
+## APPENDIX A.III
+
+### Bit rate consideration for SMATV distribution systems
+
+(to Annex A of Recommendation J.84)
+
+In order to achieve a transparent retransmission of satellite services on SMATV systems, it is necessary to take into account the limitations imposed by the SMATV System A1 in the 8 MHz cable channel bandwidth.
+
+Table A.III.1 gives figures, showing the possible ranges of SMATV symbol rates and occupied bandwidths for different useful bit rates on the satellite. The 16-QAM, 32-QAM and 64-QAM constellations of the SMATV System A1 are considered.
+
+For full transparency, the same useful bit rate (excluding RS coding) should be used in the satellite and the SMATV cable network.
+
+The theoretical maximum symbol rate in an 8 MHz SMATV channel is 6.96 MBaud with a roll-off factor of 0.15. In Table A.III.1 indicative useful bit rates are provided.
+
+Channel bandwidth constraints exist in a number of high loaded SMATV networks, which limit the useful bandwidth to 7 MHz. For such existing high loaded networks, transmission of symbol rates about 6 MBaud are feasible with acceptable signal degradation. Symbol rates given above the upper highlighted line support the simplified transparent transmodulation concept, facilitating the satellite link operation at BER ratios above threshold (before RS) for a given antenna size. However, future upgrading of current single channel amplifiers may clear such limitations.
+
+Table A.III.2 shows the indicative SMATV capacity in case of QPSK channels distributed in the existing extended super-band or in the existing extended IF band for the symbol rates referred in [2] in Appendix A.IV. Other symbol rates and channel spacing are possible.
+
+**Table A.III.1/J.84 – Examples of transparent retransmission of satellite TV on SMATV networks using the same useful bit rate  $R_u$  (excluding RS)**
+
+| Examples of satellite $R_u$ for BW ( $-3$ dB)/ $R_s = 1.27$ (after MPEG-2 MUX) (Mbit/s) | 16-QAM              |                   | 32-QAM              |                   | 64-QAM              |                   |
+|-----------------------------------------------------------------------------------------|---------------------|-------------------|---------------------|-------------------|---------------------|-------------------|
+|                                                                                         | Symbol rate (MBaud) | Occupied BW (MHz) | Symbol rate (MBaud) | Occupied BW (MHz) | Symbol rate (MBaud) | Occupied BW (MHz) |
+| 18.9                                                                                    | 5.13                | 5.90              | 4.10                | 4.72              | 3.42                | 3.93              |
+| 19.6                                                                                    | 5.32                | 6.11              | 4.25                | 4.89              | 3.54                | 4.07              |
+| 21.7                                                                                    | 5.88                | 6.77              | 4.70                | 5.41              | 3.92                | 4.51              |
+| 24.0                                                                                    | 6.51                | 7.49              | 5.21                | 5.99              | 4.34                | 4.99              |
+| 25.2                                                                                    | 6.84                | 7.86              | 5.47                | 6.29              | 4.56                | 5.24              |
+| 26.1                                                                                    |                     |                   | 5.66                | 6.51              | 4.72                | 5.43              |
+| 26.2                                                                                    |                     |                   | 5.68                | 6.54              | 4.74                | 5.45              |
+| 28.3                                                                                    |                     |                   | 6.14                | 7.06              | 5.12                | 5.88              |
+| 29.0                                                                                    |                     |                   | 6.29                | 7.24              | 5.24                | 6.03              |
+| 29.4                                                                                    |                     |                   | 6.38                | 7.34              | 5.32                | 6.11              |
+| 31.5                                                                                    |                     |                   | 6.84                | 7.86              | 5.70                | 6.55              |
+| 31.9                                                                                    |                     |                   | 6.92                | 7.96              | 5.77                | 6.63              |
+| 32.6                                                                                    |                     |                   |                     |                   | 5.89                | 6.78              |
+| 32.7                                                                                    |                     |                   |                     |                   | 5.91                | 6.80              |
+| 33.1                                                                                    |                     |                   |                     |                   | 5.99                | 6.88              |
+| 33.4                                                                                    |                     |                   |                     |                   | 6.04                | 6.95              |
+| 34.4                                                                                    |                     |                   |                     |                   | 6.22                | 7.15              |
+| 34.8                                                                                    |                     |                   |                     |                   | 6.29                | 7.24              |
+| 35.9                                                                                    |                     |                   |                     |                   | 6.49                | 7.47              |
+| 36.2                                                                                    |                     |                   |                     |                   | 6.55                | 7.53              |
+| 38.1                                                                                    |                     |                   |                     |                   | 6.89                | 7.92              |
+| 31.672 (PDH)                                                                            |                     |                   | 6.87                | 7.90              | 5.73                | 6.59              |
+
+![Diagram showing a 7 MHz cable channel bandwidth with a single L-shaped line.](4af57c86e477d0a9768ad67205a5a458_img.jpg)
+7 MHz Cable channel Bandwidth (BW)
+
+![Diagram showing an 8 MHz cable channel bandwidth with two nested L-shaped lines.](23a754b6aac2e0d17376bdcc9edfcfdc_img.jpg)
+8 MHz Cable channel Bandwidth (BW)
+
+**Table A.III.2/J.84 – SMATV-S and SMATV-IF capacity**
+
+| RS<br>(MBaud) | Minimum<br>channel spacing<br>(MHz) | Number of channels                             |                                                      |       |
+|---------------|-------------------------------------|------------------------------------------------|------------------------------------------------------|-------|
+|               |                                     | Extended super-band<br>(230-470 MHz)<br>(Note) | Satellite first IF band<br>(0.95-2.05 GHz)<br>(Note) | Total |
+| 42.2          | 57.0                                | 4                                              | 19                                                   | 23    |
+| 35.9          | 48.5                                | 4                                              | 22                                                   | 26    |
+| 31.5          | 42.5                                | 5                                              | 25                                                   | 30    |
+| 28.1          | 37.9                                | 6                                              | 28                                                   | 34    |
+| 25.8          | 34.8                                | 6                                              | 31                                                   | 37    |
+| 23.4          | 31.6                                | 7                                              | 34                                                   | 41    |
+| 21.1          | 28.5                                | 8                                              | 38                                                   | 46    |
+| 20.3          | 27.4                                | 8                                              | 40                                                   | 48    |
+
+NOTE – The frequency ranges in parenthesis are only indicative. Wider ranges may be possible in some circumstances.
+
+## APPENDIX A.IV
+
+(to Annex A of Recommendation J.84)
+
+### Bibliography
+
+- [1] REIMERS (U.): The European perspectives on Digital Television Broadcasting, *NAB'93, document GT V4/MOD 249*.
+- [2] MASENTO (A.), MIGNONE (V.), MORELLO (A.): Performance of 64-QAM and QPSK in SMATV installations – Simulation results, *Report No. 94/xx/E*.
+- [3] GARAZZINO (G.), SARDELLA (V.): Preliminary 16-QAM transmission tests in the UHF Band on a SMATV network, *RAI Technical Report No. 94/28/I*.
+- [4] BENVENISTE (A.), GOURSAT (M.): Blind equalizers, *IEEE Trans. Comm.*, Vol. COM-32, pp. 871-883, August 1984.
+- [5] DVB-TM 1259: Satellite digital TV in collective antenna systems – SMATV reference channel model for digital TV, *RACE DIGISMATV Project*, July 1994.
+- [6] DTVB 1190/DTVC 38: Specification of modulation, channel coding and framing structure for the Baseline System for digital multi-programme television by cable, 3rd revised version, February 1994.
+- [7] DTVB 1110/GT V4/MOD 252/ DTVC 18: Specification of the "Baseline modulation/channel coding system" for digital multi-programme television by satellite, 7th revised version, January 1994.
+- [8] CENELEC prEN 50083-3, June 1993.
+
+## ANNEX B
+
+## Digital multi-programme SMATV System B
+
+System B of ITU-T J.83 has no companion SMATV system.
+
+# ANNEX C
+
+## Digital multi-programme SMATV System C
+
+### C.1 Scope
+
+This annex describes a System C transmission system that distributes digital multiple-programme television suitable for distribution in Satellite Master Antenna Television (SMATV) systems. The SMATV network architecture is described and is complementary to Annex C/J.83 [1]. System C is based on the MPEG-2 system layer [3], with the addition of an appropriate Forward Error Correction (FEC) technique.
+
+### C.2 SMATV distribution system concept
+
+The aim of SMATV is to distribute television and sound programme signals broadcast from satellites to several households in a neighbourhood and/or within households located in one building or in several adjacent buildings. These signals are received by a satellite receiving antenna and are distributed together with other broadcast signals. SMATV subscribers share a common satellite antenna, which transmits satellite signals to Integrated Receiver Decoders (IRDs) in homes transparently and without baseband processing.
+
+This annex describes three options for SMATV systems for distributing digital television signals:
+
+#### a) *SMATV system C(I)*
+
+This system receives satellite broadcast signals with a satellite receiving antenna. The signals as defined in [2], [5] and [6], are distributed at the intermediate frequency delivered by the Low Noise Block (LNB) of the receiving antenna. The signals are received with IRDs designed for receiving satellite broadcasts.
+
+#### b) *SMATV system C(II)*
+
+This system receives satellite broadcast BPSK, QPSK, or 8PSK signals with a satellite receiving antenna and converts the frequencies of the output signals of the LNB to a frequency band appropriate for the distribution network. The frequency re-allocated signals are received with IRDs designed for receiving satellite broadcasts.
+
+#### c) *SMATV system C(III)*
+
+This system receives satellite broadcast BPSK, QPSK, or 8PSK signals with a satellite receiving antenna, demodulates them to remove some of error correction bits, and then remodulates them as 64-QAM signals as defined in Annex C/J.83 [1] for distribution. This system remodulates signals transparently. The signals are received with IRDs designed for receiving cable television rather than ones for satellite broadcasts.
+
+### C.3 SMATV system C(I)
+
+SMATV System C(I) is a distribution network using BPSK, QPSK, or 8PSK-modulated signals. The BPSK, QPSK, or 8PSK-modulated signals from a satellite are received by a satellite receiving antenna, and the LNB output signals are led directly to an SMATV distribution network, where they may be multiplexed and distributed with other signals. They are received with BPSK, QPSK, or 8PSK IRDs for satellite broadcasts.
+
+As shown in Figure C.1, the satellite signals reach satellite-broadcast IRDs without any demodulation or remodulation.
+
+![Figure C.1/J.84 – SMATV System C(I) block diagram](aaf3e6e44cdeabd6d1df869c5f392ea1_img.jpg)
+
+This block diagram illustrates SMATV System C(I). On the left, a 'Receiving antenna for satellite broadcasting' is connected to an 'LNB'. The output of the LNB and 'Other signals' are fed into a central 'SMATV distribution network'. The network has two outputs on the right: one connected to a 'PSK IRD' and another connected to a group of 'Other IRD' units. The identifier 'T0903320-96' is located at the bottom right of the diagram.
+
+Figure C.1/J.84 – SMATV System C(I) block diagram
+
+**Figure C.1/J.84 – SMATV System C(I)**
+
+### C.4 SMATV system C(II)
+
+SMATV System C(II) is a distribution network using BPSK, QPSK, or 8PSK-modulated signals. The BPSK, QPSK, or 8PSK-modulated signals from satellites are received with satellite antennas. One or more outputs of the LNB are frequency-converted and frequency re-allocated, and are then fed into an SMATV distribution network, where they may be multiplexed and distributed with other signals. They are received with BPSK, QPSK, or 8PSK IRDs designed for satellite broadcasts. Frequency converters may be used with the IRDs if necessary. This system is applicable to a distribution network that cannot handle the frequency band of the LNB output.
+
+As shown in Figure C.2, the satellite signals reach satellite-broadcast IRDs after frequency-conversion without any demodulation or remodulation.
+
+![Figure C.2/J.84 – SMATV System C(II) block diagram](4cde160bcc69b7b6c81b648dd0e4252e_img.jpg)
+
+This block diagram illustrates SMATV System C(II). On the left, multiple 'Receiving antennas for satellite broadcasting' are connected to 'LNB1' and 'LNB2'. The outputs of these LNBs are fed into 'Freq. conv. 1' and 'Freq. conv. 2' respectively. The outputs of these converters are then combined in a 'MIX' block. 'Other signals' are also fed into this 'MIX' block. The output of the 'MIX' block is connected to a central 'SMATV distribution network'. The network has two outputs on the right: one connected to a 'Freq. conv.' block which then connects to a 'PSK IRD', and another connected to a group of 'Other IRD' units. The identifier 'T0903330-96' is located at the bottom right of the diagram.
+
+Figure C.2/J.84 – SMATV System C(II) block diagram
+
+**Figure C.2/J.84 – SMATV System C(II)**
+
+### C.5 SMATV system C(III)
+
+SMATV System C(III) is a distribution network using 64 QAM-modulated signals. The BPSK, QPSK, or 8PSK-modulated signals from a satellite are received with a satellite antenna and are remodulated as 64-QAM signals for distribution in an SMATV distribution network. BPSK, QPSK, or 8PSK-to 64-QAM transmodulators at the head-end convert the BPSK, QPSK, or 8PSK-demodulated bit streams into 64-QAM signals, which are described in Annex C/J.83. The channel coding shall include RS coding and interleaving but not convolutional coding. The signals are transmitted to a distribution network, where they may be multiplexed and distributed with other signals. The 64-QAM signals are received with 64 QAM IRDs conforming to Annex C/J.83.
+
+As shown in Figure C.3, the satellite signals reach 64 QAM IRDs after demodulation and remodulation.
+
+![Block diagram of SMATV System C(III). A receiving antenna for satellite broadcasting is connected to an LNB. The LNB output is connected to two PSK to 64-QAM transmodulators. Below these transmodulators, there are vertical dots and an arrow labeled '(Other signals)' pointing into the mix. The outputs of the transmodulators are connected to a MIX block. The MIX block output is connected to an SMATV distribution network. The SMATV distribution network is connected to a 64 QAM IRD and an Other IRD. A label T0903340-96 is present near the bottom right of the diagram.](d17aa1fcc3b86503ad1dd0717a6c34c2_img.jpg)
+
+Block diagram of SMATV System C(III). A receiving antenna for satellite broadcasting is connected to an LNB. The LNB output is connected to two PSK to 64-QAM transmodulators. Below these transmodulators, there are vertical dots and an arrow labeled '(Other signals)' pointing into the mix. The outputs of the transmodulators are connected to a MIX block. The MIX block output is connected to an SMATV distribution network. The SMATV distribution network is connected to a 64 QAM IRD and an Other IRD. A label T0903340-96 is present near the bottom right of the diagram.
+
+Figure C.3/J.84 – SMATV System C(III)
+
+### C.6 MPEG-2 transport layer
+
+The SMATV System shall use the MPEG-2 transport layer, which is defined in [3]. The Transport Layer for MPEG-2 data is comprised of packets having 188 bytes, with one byte for synchronization purposes, three bytes of header containing service identification, scrambling and control information, followed by 184 bytes of MPEG-2 or auxiliary data.
+
+### C.7 Framing structure for channel coding
+
+The framing organization of the SMATV system shall be based on the structure of MPEG-2 transport packets (see [1] and [2]).
+
+## ANNEX D
+
+## Digital multi-programme SMATV System D
+
+### D.1 Introduction
+
+This annex describes the head-end processing and equipment configuration suitable for SMATV systems by the use of the 16-VSB cable mode of the VSB (Vestigial SideBand) digital transmission system. The architecture of the SMATV network is indicated in Figure D.1. The system is coherent with the description in Annex D/J.83.
+
+### D.2 SMATV VSB system concept
+
+A possible configuration of head-end equipment suitable for SMATV systems (as well as cable distribution head-ends) is shown in Figure D.1. Although the signal path is pointed out for the satellite reception and insertion into an SMATV network, there are other possibilities to feed the system (such as terrestrial).
+
+Shown at the top of Figure D.1 is a satellite received source of MPEG-2/188 byte packets provided by appropriate demodulator and interface circuitry.
+
+The MPEG-2/188 byte packet sources are shown combined in Figure D.1 by an Interface/Buffer and fed to a 16-VSB cable head-end transmitter (described in [1]), the output of which may be combined with other RF signal sources. As shown, the payload bit rate of 16-VSB, which is a nominal 38.78 Mbit/s (for a 6 MHz channel), is partially provided by the satellite source and partly by other digital sources. In the event that the satellite source provides a data rate equal to the capability of one 16-VSB channel, an additional 16-VSB head-end transmitter can process other digital sources (terrestrial or satellite).
+
+Other VSB modes are available as defined in D.8/J.83.
+
+### **D.3 SMATV head-end commonalities**
+
+SMATV installations are typically used in private cable systems of multiple dwellings where the head-end is unattended and makes use of consumer grade equipment. The configuration shown in Figure D.1 is expected to meet that requirement, in as much as the components, such as integrated circuits, are those expected to be used in digital terrestrial receivers.
+
+### **D.4 Conclusion**
+
+An SMATV head-end configuration for satellite reception has been described which presents commonalities with other digital delivered signals, and is affordable and rugged to meet requirements of typical SMATV head-ends.
+
+![Block diagram of SMATV head-end equipment configuration showing signal flow from satellite and other sources through various processing stages to a distribution network.](11edb7fcedf09ac6a817f8d7b8c61eec_img.jpg)
+
+```
+
+graph LR
+    Satellite[Satellite Dish] --> ST[Satellite tuner and IF]
+    ST --> QD[QPSK demodulator]
+    OS["Other sources  
+MPEG-2 188 byte packets"] --> IB[Interface/Buffer]
+    QD --> IB
+    IB --> DR[Data randomizer]
+    DR --> RSE[Reed-Solomon encoder]
+    RSE --> DI[Data interleaver]
+    DI --> M[Mapper]
+    M --> MX[MUX]
+    SS["Segment sync"] --> MX
+    FS["Field sync"] --> MX
+    MX --> PI[Pilot insertion]
+    PI --> VM[VSB modulator]
+    VM --> RUC[RF up-converter]
+    RUC --> C[Combiner]
+    C --> DN["Distribution  
+SMATV network"]
+  
+```
+
+The diagram illustrates the equipment configuration for an SMATV head-end. It begins with a satellite dish connected to a 'Satellite tuner and IF' block, which then connects to a 'QPSK demodulator'. The output of the demodulator and 'Other sources' (labeled 'MPEG-2 188 byte packets') are fed into an 'Interface/Buffer' block. The output of this buffer goes to a 'Data randomizer', followed by a 'Reed-Solomon encoder', 'Data interleaver', and 'Mapper'. The 'Mapper' output is fed into a 'MUX' block, which also receives 'Segment sync' and 'Field sync' inputs. The 'MUX' output goes to 'Pilot insertion', then a 'VSB modulator', and an 'RF up-converter'. The output of the 'RF up-converter' is fed into a 'Combiner' block. The 'Combiner' has four other inputs from the left and its output is labeled 'Distribution SMATV network'. A small circle with a dot is shown on the output line of the combiner.
+
+Block diagram of SMATV head-end equipment configuration showing signal flow from satellite and other sources through various processing stages to a distribution network.
+
+T0903150-95
+
+**Figure D.1/J.84 – SMATV head-end equipment configuration**
+
+# 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                                                                                            |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b>                             |
+| 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
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+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**J.900**
+
+(10/2014)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Transmission of 3-D TV services – Free viewpoint TV
+
+---
+
+**Requirements for stereoscopic three  
+dimensional television service over hybrid fibre  
+and coaxial based networks**
+
+Recommendation ITU-T J.900
+
+
+
+# Recommendation ITU-T J.900
+
+## Requirements for stereoscopic three dimensional television service over hybrid fibre and coaxial based networks
+
+## Summary
+
+As digital broadcasting services have been rapidly deployed, many service operators are introducing more realistic broadcasting services such as three-dimensional television (3DTV). Recently, several research activities in Europe, Asia and North America for the 3DTV service have been completed. Moreover, some 3DTV service trials have been executed for various broadcasting media including terrestrial, cable and satellite TV. Recommendation ITU-T J.900 describes the services and system requirements for stereoscopic 3DTV service over hybrid fibre and coaxial (HFC) based networks. For providing cable 3DTV services, there are several technologies to be considered; 3D video format, video quality, service signalling, contents delivery, transmission efficiency and so on. Although a wide range of 3DTV technologies have been developed, 3D video services and content markets are still premature. Therefore, it is necessary to define the service and system requirements of 3DTV broadcasting for vitalization of 3D video services and related content markets.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T J.900    | 2014-10-29 | 9           | <a href="http://handle.itu.int/11.1002/1000/12322">11.1002/1000/12322</a> |
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## 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 <http://www.itu.int/ITU-T/ipr/>.
+
+© 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 .....                                                                       | 1    |
+| 3.1 Terms defined elsewhere .....                                                         | 1    |
+| 3.2 Terms defined in this Recommendation.....                                             | 1    |
+| 4 Abbreviations and acronyms .....                                                        | 2    |
+| 5 Conventions .....                                                                       | 2    |
+| 6 Service and system overview.....                                                        | 2    |
+| 7 Service requirements .....                                                              | 3    |
+| 7.1 Video quality .....                                                                   | 3    |
+| 7.2 Visual fatigue.....                                                                   | 3    |
+| 7.3 Video signal expression.....                                                          | 3    |
+| 7.4 Compatibility with existing HDTV receivers.....                                       | 4    |
+| 7.5 2D/3D switched broadcasting service .....                                             | 4    |
+| 7.6 Conditional access .....                                                              | 4    |
+| 7.7 Additional information service (subtitles, electronic programme guide,<br>etc.) ..... | 4    |
+| 8 System requirements.....                                                                | 4    |
+| 8.1 Video signal format .....                                                             | 4    |
+| 8.2 Multiplexing .....                                                                    | 5    |
+| 8.3 Service information .....                                                             | 5    |
+| Bibliography.....                                                                         | 6    |
+
+
+
+# Recommendation ITU-T J.900
+
+## Requirements for stereoscopic three dimensional television service over hybrid fibre and coaxial based networks
+
+# 1 Scope
+
+This Recommendation defines service and system requirements for stereoscopic, three dimensional television (3DTV) transmission over HFC based network. The stereoscopic 3DTV is the service to provide realistic broadcasting services to cable service subscribers. The service requirements in this Recommendation include video quality, video fatigue, video signal expression, compatibility, 2D/3D switched service, conditional access and additional information. The system requirements in this Recommendation include video signal formats, multiplexing and service information.
+
+# 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 H.222.0] Recommendation ITU-T H.222.0 (2012) | ISO/IEC 13818-1:2013, *Information technology – Generic coding of moving pictures and associated audio information: Systems*.
+
+[ITU-R BT.2021] Recommendation ITU-R BT.2021 (2012), *Subjective methods for the assessment of stereoscopic 3DTV systems*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 frame compatible** [b-ETSI TS 101 547-1]: Arrangement of the left and right images in a spatial multiplex which results in an image which can be treated like a normal HDTV image by the receiver demodulator and compression decoder.
+
+**3.1.2 service compatible** [b-ETSI TS 101 547-1]: Arrangement of the left and right images such that an existing HDTV receiver is able to extract a 2D version of the video content from a stereoscopic 3DTV service.
+
+**3.1.3 stereoscopic** [b-ETSI TS 101 547-1]: Three-dimensional picture that uses two single pictures, left and right, displayed on a single plane surface (the TV screen in the case of 3DTV).
+
+## 3.2 Terms defined in this Recommendation
+
+None.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|        |                                        |
+|--------|----------------------------------------|
+| 2D     | Two Dimension                          |
+| 3D     | Three Dimension                        |
+| 3DTV   | Three Dimensional Television           |
+| EPG    | Electronic Programme Guide             |
+| ES     | Elementary Stream                      |
+| FC     | Frame Compatible                       |
+| HD     | High Definition                        |
+| HDTV   | High Definition Television             |
+| HFC    | Hybrid Fibre and Coaxial               |
+| MPEG-2 | Motion Picture Experts Group version 2 |
+| PSI    | Programme Specific Information         |
+| SC     | Service Compatible                     |
+| SI     | Service Information                    |
+| STB    | Set-Top Box                            |
+| TS     | Transport Stream                       |
+| VoD    | Video-on-Demand                        |
+
+# 5 Conventions
+
+In this Recommendation:
+
+The keywords "**is required to**" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed.
+
+The keywords "**is recommended**" indicate a requirement which is recommended but which is not absolutely required. Thus this requirement need not be present to claim conformance.
+
+The keywords "**is prohibited from**" indicate a requirement which must be strictly followed and from which no deviation is permitted if conformance to this Recommendation is to be claimed.
+
+The keywords "**can optionally**" indicate an optional requirement which is permissible, without implying any sense of being recommended. This term is not intended to imply that the vendor's implementation must provide the option and the feature can be optionally enabled by the network operator/service provider. Rather, it means the vendor may optionally provide the feature and still claim conformance with the specification.
+
+In the body of this Recommendation and its annexes, the words *shall*, *shall not*, *should* and *may* sometimes appear, in which case they are to be interpreted, respectively, as *is required to*, *is prohibited from*, *is recommended* and *can optionally*. The appearance of such phrases or keywords in an appendix or in material explicitly marked as *informative* are to be interpreted as having no normative intent.
+
+## 6 Service and system overview
+
+Stereoscopic 3DTV service over HFC-based network can be provided on digital cable 3D broadcasting system shown in Figure 1. Digital cable 3D broadcasting system can reuse the existing HDTV delivery infrastructure with some complications that need to be address around 3DTV service configuration. It provides real-time and non-real-time 3DTV services. It can provide frame
+
+compatible stereoscopic 3DTV services and service compatible stereoscopic 3DTV services. It can also enable the mixed use of 2D/3D programmes time-wise.
+
+![Figure 1 – Digital cable 3DTV broadcasting service and system. The diagram shows the flow of video signals from various providers through a central multiplexing unit to an HFC network, and finally to 3DTV and HDTV set-top boxes (STBs) for service delivery. Providers include SC-3DTV, FC-3DTV, 3DTV VoD, and HDTV. The central unit includes blocks for 3DTV video, SC-3DTV encoding, FC-3DTV encoding, 3DTV VoD, Additional data, and Signalling and service information. The HFC network is represented by a cloud icon. The output shows a 3DTV service and an HDTV service.](acfc53eca625d62b38aa2563efa95c3e_img.jpg)
+
+The diagram illustrates the digital cable 3DTV broadcasting system. On the left, four service providers are shown: SC-3DTV service provider, FC-3DTV service provider, 3DTV VoD provider, and HDTV service provider. Each provider sends a video signal to a central 'Transport multiplexing and transmission' unit. The SC-3DTV and FC-3DTV providers send '3DTV video' which is then processed by 'SC-3DTV encoding' and 'FC-3DTV encoding' respectively. The 3DTV VoD provider sends '3DTV VoD'. The HDTV provider sends 'HDTV video' which is processed by 'HDTV encoding'. All these signals, along with 'Additional data' and 'Signalling and service information', are multiplexed and transmitted through an 'HFC network' (represented by a cloud). The output of the HFC network is connected to two set-top boxes (STBs): a '3DTV STB' and an 'HDTV STB'. The 3DTV STB outputs a '3DTV service' (shown with a cartoon character), and the HDTV STB outputs an 'HDTV service' (also shown with a cartoon character). The diagram is labeled 'J.900(14)\_F01' in the bottom right corner.
+
+Figure 1 – Digital cable 3DTV broadcasting service and system. The diagram shows the flow of video signals from various providers through a central multiplexing unit to an HFC network, and finally to 3DTV and HDTV set-top boxes (STBs) for service delivery. Providers include SC-3DTV, FC-3DTV, 3DTV VoD, and HDTV. The central unit includes blocks for 3DTV video, SC-3DTV encoding, FC-3DTV encoding, 3DTV VoD, Additional data, and Signalling and service information. The HFC network is represented by a cloud icon. The output shows a 3DTV service and an HDTV service.
+
+**Figure 1 – Digital cable 3DTV broadcasting service and system**
+
+3DTV stereoscopic services can be divided as shown below. The services are classified according to channel configuration, 2D compatibility and 3D programme configuration.
+
+- 2DTV Compatible 3DTV Service: To provide 3DTV service that ensures compatibility with the legacy 2DTV service
+- 2D/3DTV Simultaneous Service: To provide the legacy 2DTV service and 3DTV service in correspondence with 2DTV service.
+- 3DTV Exclusive Service: To provide 3D service only without compatibility with the legacy 2DTV service
+
+# 7 Service requirements
+
+### 7.1 Video quality
+
+The stereoscopic 3DTV service is required to provide the picture quality of at least the "4th scale level (Good)" according to subjective method for the assessment of picture quality of [ITU-R BT.2021].
+
+The stereoscopic 3DTV service is required to provide the depth quality of at least the "4th scale level (Good)" according to subjective method for the assessment of depth quality of [ITU-R BT.2021].
+
+### 7.2 Visual fatigue
+
+The stereoscopic 3DTV service is required to provide the visual comfort of at least the "4th scale level (Comfortable)" according to subjective method for the assessment of visual comfort of [ITU-R BT.2021].
+
+## 7.3 Video signal expression
+
+The stereoscopic 3DTV service is required to include the video aspect ratio of 16:9.
+
+The stereoscopic 3DTV service is required to include half HD resolution for left/right video respectively when a frame compatible 3DTV service is provided.
+
+The stereoscopic 3DTV service is required to include HD resolution for left/right video respectively when a service compatible 3DTV service is provided.
+
+## **7.4 Compatibility with existing HDTV receivers**
+
+The stereoscopic 3DTV service is recommended to provide backward compatibility with existing HDTV receivers so that the existing HDTV receivers can receive a 3DTV video programme and display it as a 2D video.
+
+### **7.5 2D/3D switched broadcasting service**
+
+The stereoscopic 3DTV service is required to switch between 3DTV and 2DTV services in the same channel.
+
+The stereoscopic 3DTV service is required to provide a method which can automatically distinguish and display either 2D or 3D broadcasting service in order to minimize viewers' inconvenience.
+
+## **7.6 Conditional access**
+
+The stereoscopic 3DTV service is recommended to apply conditional access in order to provide a subscription-based 3D broadcasting service.
+
+### **7.7 Additional information service (subtitles, electronic programme guide, etc.)**
+
+The stereoscopic 3DTV service is recommended to provide additional information services related to the 3DTV contents.
+
+The stereoscopic 3DTV service is recommended to minimize viewers' visual fatigue when the additional information is displayed together with the 3DTV contents.
+
+# **8 System requirements**
+
+### **8.1 Video signal format**
+
+#### **8.1.1 Service compatible**
+
+The stereoscopic 3DTV system is required to support service compatible formats that consist of left and right video signals each within a separate picture frame.
+
+The stereoscopic 3DTV system is recommended to conform to the video signal format of Table 1 for each left and right video signal.
+
+**Table 1 – Video signal format**
+
+| <b>Number of scanning lines</b> | <b>Number of pixels</b> | <b>Screen ratio</b> | <b>Sampling format</b> | <b>Screen playing ratio (Hz)</b>                          |
+|---------------------------------|-------------------------|---------------------|------------------------|-----------------------------------------------------------|
+| 1080                            | 1920                    | 16:9                | 4:2:0                  | 59,94/60I, 59,94/60P, 50I, 50P, 29,97/30P, 25P, 23,98/24P |
+| 720                             | 1280                    | 16:9                | 4:2:0                  | 59,94/60P, 50P, 29,97/30P, 25P, 23,98/24P                 |
+
+#### **8.1.2 Frame compatible**
+
+The stereoscopic 3DTV system is required to support frame compatible formats, such as side-by-side and top-and-bottom, which consist of left and right video signals within one picture frame.
+
+The stereoscopic 3DTV system is recommended to satisfy a half number of scanning lines or pixels of the video signal format of Table 1 for each left and right video signal.
+
+### **8.2 Multiplexing**
+
+#### **8.2.1 Basic unit of multiplexing**
+
+The stereoscopic 3DTV system is required to use MPEG-2 TS packet as the basic unit for multiplexing 3D video, audio and data [ITU-T H.222.0].
+
+#### **8.2.2 Programme specific information**
+
+The stereoscopic 3DTV system is required to provide programme specific information (PSI) signalling information in order to distinguish between 2D broadcasting service and 3D broadcasting service.
+
+The stereoscopic 3DTV system is required to include PSI signalling information in order to distinguish between left and right video signals.
+
+The stereoscopic 3DTV system is required to ensure that the added PSI signalling information for 3DTV service does not affect the operation of existing HDTV receiver.
+
+## **8.3 Service information**
+
+The stereoscopic 3DTV system is required to provide service information (SI) in order to distinguish between 2D broadcasting service and 3D broadcasting service.
+
+The stereoscopic 3DTV system is required to provide guide information related to 3D broadcasting service.
+
+The stereoscopic 3DTV system is required to provide channel information related to the transmission of 3D broadcasting service.
+
+The stereoscopic 3DTV system is required to ensure that the added SI information for 3DTV service does not affect the operation of existing HDTV receiver.
+
+## Bibliography
+
+- [b-ETSI TS 101 547-1] ETSI TS 101 547-1 V1.1.1 (2012), *Digital Video Broadcasting (DVB); Plano-stereoscopic 3DTV; Part 1: Overview of the multipart.*
+- [b-ETSI TS 101 547-2] ETSI TS 101 547-2 V1.2.1 (2012), *Digital Video Broadcasting (DVB); Plano-stereoscopic 3DTV; Part 2: Frame Compatible Plano-stereoscopic 3DTV.*
+- [b-ETSI TS 101 547-3] ETSI TS 101 547-3 V1.1.1 (2012), *Digital Video Broadcasting (DVB); Plano-stereoscopic 3DTV; Part 3: HDTV Service Compatible Plano-stereoscopic 3DTV.*
+- [b-ANSI/SCTE 187-1] ANSI/SCTE 187-1 (2012), *Stereoscopic 3D Formatting and Coding for Cable.*
+- [b-ANSI/SCTE 187-2] ANSI/SCTE 187-2 (2012), *Stereoscopic 3D PSI Signaling.*
+- [b-ANSI/SCTE 187-3] ANSI/SCTE 187-3 (2012), *Informative Guidance for Stereoscopic Video.*
+
+
+
+## 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                                                                |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b> |
+| 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
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@@ -0,0 +1,510 @@
+
+
+![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
+
+**J.96**
+
+(07/2002)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Ancillary digital services for television transmission
+
+---
+
+**Technical method for ensuring privacy in  
+long-distance international MPEG-2 television  
+transmission conforming to  
+ITU-T Recommendation J.89**
+
+ITU-T Recommendation J.96
+
+---
+
+# ITU-T J-SERIES RECOMMENDATIONS
+
+# CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS
+
+|                                                                                                 |                  |
+|-------------------------------------------------------------------------------------------------|------------------|
+| General Recommendations                                                                         | J.1–J.9          |
+| General specifications for analogue sound-programme transmission                                | J.10–J.19        |
+| Performance characteristics of analogue sound-programme circuits                                | J.20–J.29        |
+| Equipment and lines used for analogue sound-programme circuits                                  | J.30–J.39        |
+| Digital encoders for analogue sound-programme signals                                           | J.40–J.49        |
+| Digital transmission of sound-programme signals                                                 | J.50–J.59        |
+| Circuits for analogue television transmission                                                   | J.60–J.69        |
+| Analogue television transmission over metallic lines and interconnection with radio-relay links | J.70–J.79        |
+| Digital transmission of television signals                                                      | J.80–J.89        |
+| <b>Ancillary digital services for television transmission</b>                                   | <b>J.90–J.99</b> |
+| Operational requirements and methods for television transmission                                | J.100–J.109      |
+| Interactive systems for digital television distribution                                         | J.110–J.129      |
+| Transport of MPEG-2 signals on packetised networks                                              | J.130–J.139      |
+| Measurement of the quality of service                                                           | J.140–J.149      |
+| Digital television distribution through local subscriber networks                               | J.150–J.159      |
+| IPCablecom                                                                                      | J.160–J.179      |
+| Miscellaneous                                                                                   | J.180–J.199      |
+| Application for Interactive Digital Television                                                  | J.200–J.209      |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+## **ITU-T Recommendation J.96**
+
+## **Technical method for ensuring privacy in long-distance international MPEG-2 television transmission conforming to ITU-T Recommendation J.89**
+
+## **Summary**
+
+This ITU-T Recommendation describes a Basic Interoperable Scrambling System (BISS-E) for use on digital contribution circuits (satellite, DSNG, etc.) compliant with ITU-T Rec. J.89, which uses fixed keys. BISS-E uses encrypted Session Words and allows centrally managed conditional access.
+
+### **Source**
+
+ITU-T Recommendation J.96 was revised by ITU-T Study Group 9 (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 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 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     | Informative reference.....                  | 1 |
+| 3     | Definitions .....                           | 1 |
+| 4     | Abbreviations.....                          | 2 |
+| 5     | Security requirements .....                 | 2 |
+| 6     | Modes of operation .....                    | 3 |
+| 7     | Mode 0 .....                                | 3 |
+| 8     | BISS Mode 1 – Functional requirements.....  | 3 |
+| 8.1   | Overview .....                              | 3 |
+| 8.2   | CA_descriptor.....                          | 4 |
+| 9     | BISS Mode E – Functional requirements ..... | 4 |
+| 9.1   | Clear Session Word .....                    | 4 |
+| 9.2   | Encrypted Session Word .....                | 4 |
+| 9.3   | Decryption scheme .....                     | 5 |
+| 9.3.1 | Overview .....                              | 5 |
+| 9.3.2 | Unit identifiers.....                       | 5 |
+| 9.3.3 | Decryption function.....                    | 6 |
+| 9.3.4 | Post-processing function .....              | 8 |
+
+
+
+## Technical method for ensuring privacy in long-distance international MPEG-2 television transmission conforming to ITU-T Recommendation J.89
+
+# 1 Scope
+
+This Recommendation constitutes a common standard for a conditional access system for long distance international transmission of digital television according to MPEG Professional Profile (4:2:2).
+
+The rapid increase in the use of Digital Satellite News Gathering (DSNG) technology has resulted in the availability of digital codec equipment from a number of vendors. At the same time, the absence of standard methods for the securing and scrambling of DSNG broadcasts has spawned the development of several different proprietary security mechanisms.
+
+The widespread acceptance of DVB standards now makes it possible to propose and provide a security mechanism that offers interoperability between the equipment of different DSNG vendors. This would enable broadcasters to combine equipment from several vendors, while making systems more future-proof.
+
+The Basic Interoperable Scrambling System (BISS) is based on the DVB-CSA specification [1], and the use of fixed clear keys called Session Words (SWs). BISS specification Mode 1 is used for DSNG.
+
+BISS specification Mode E (BISS with Encrypted keys – referred to as BISS-E) introduces an additional mechanism to accept the insertion of Encrypted Session Words (ESWs) while, at the same time, conserving interoperability. This mechanism is backward-compatible with BISS specification Mode 1.
+
+# 2 Informative reference
+
+- EBU Technical Document: Tech 3292 rev.2 (2002), *BISS-E – Basic Interoperable Scrambling System with Encrypted keys*.
+
+# 3 Definitions
+
+This Recommendation defines the following terms:
+
+- 3.1 scrambler:** relates to the overall mechanisms required to meet the DVB-CSA specification.
+- 3.2 session word:** relates to the word assigned during a transmission by the Management Centre.
+- 3.3 unit:** relates to a device for which this Recommendation might apply.
+- 3.4 management centre:** refers to an organization controlling or managing the conditional access system.
+- 3.5 decryption function:** refers to a logical function used to decrypt the Encrypted Session Words, with the help of a key.
+- 3.6 interoperable function:** refers to a decryption function that shall be embedded in all units.
+
+The bits in binary numbers or sequences are numbered from the left, according to engineering notation. Bit 0 is on the right and is the least significant one; the bit on the left is the most significant one.
+
+Here is an example of engineering notation for an n-bit number:
+
+$$b_{n-1}b_{n-2} \dots b_1b_0$$
+
+# 4 Abbreviations
+
+This Recommendation uses the following abbreviations:
+
+|        |                                              |
+|--------|----------------------------------------------|
+| BISS   | Basic Interoperable Scrambling System        |
+| bslbf  | Bit String, Left Bit First                   |
+| CA     | Conditional Access                           |
+| CAT    | Conditional Access Table                     |
+| CSA    | (DVB) Common Scrambling Algorithm            |
+| CW     | Control Word                                 |
+| DES    | Data Encryption Standard                     |
+| DSNG   | Digital Satellite News Gathering             |
+| DVB    | Digital Video Broadcasting                   |
+| ECB    | Electronic Codebook                          |
+| ECM    | Entitlement Control Message                  |
+| EMM    | Entitlement Management Message               |
+| ESW    | Encrypted Session Word                       |
+| lsb    | Least Significant Bit                        |
+| LSB    | Least Significant Byte                       |
+| MC     | Management Centre                            |
+| msb    | Most Significant Bit                         |
+| MSB    | Most Significant Byte                        |
+| PID    | Packet Identification number                 |
+| PMT    | Programme Map Table                          |
+| SW     | Session Word                                 |
+| uimsbf | Unsigned Integer, Most Significant Bit First |
+
+# 5 Security requirements
+
+The DSNG model requires the direct entry of a Session Word at the transmitter and receiver, to control access to the transmission. The sender and receiver(s) of the transmission share the SW, such that only the intended parties will receive the transmission, outlined as follows:
+
+- 1) The Session Word is entered at the DSNG unit in the field, or at the transmitting earthstation.
+- 2) The Session Word is entered at the receiving IRDs.
+- 3) If the Session Words are the same, then the IRDs are able to decrypt the broadcast.
+- 4) If the Session Words are different, then the broadcast is not received.
+
+The security requirements for fixed contribution systems are somewhat different to the DSNG model. The secure exchange of SWs is fundamental to such systems and is achievable by encrypting them.
+
+# 6 Modes of operation
+
+The Scrambler must be capable of supporting the following three modes of operation:
+
+- **Mode 0:** No scrambling.
+- **Mode 1:** All components are scrambled by a fixed Control Word (CW), derived from a clear SW.
+- **Mode E:** All components are scrambled by a fixed CW, derived from an Encrypted Session Word (ESW).
+
+The scrambling mechanism, as defined in the DVB-CSA specification, shall be applied at the Transport level only.
+
+A Conditional Access Table (CAT) shall be present in the multiplex for BISS Mode 1 and BISS-E, although the table shall be empty as no Entitlement Management Message (EMM) stream will be present.
+
+NOTE – A Scrambler that only supports a subset of the defined modes of operation must do so according to an imposed hierarchy. A Scrambler providing support for Mode E must also support Modes 0 and 1.
+
+# 7 Mode 0
+
+The Scrambler must be capable of disabling the scrambling operation. In this mode, there will be no *CA\_descriptor* in the Programme Map Table (PMT) and no Entitlement Control Message (ECM) stream. The *Transport\_Scrambling\_Control* bits of the Transport Packets will be set to "00".
+
+# 8 BISS Mode 1 – Functional requirements
+
+## 8.1 Overview
+
+This mode has been designed specifically for DSNG applications, fly-away operations, emergency situations, etc. It may also be used as a fall-back solution while using the complete BISS-E system. In Mode 1, a fixed 12-character SW is inserted in the scrambler. The 64-bit CW is derived from the SW according to the DVB-CSA specification.
+
+Manual entry of the SW shall be in hexadecimal notation, with the digits entered most-significant-nibble first, i.e. from left to right as viewed in hexadecimal notation.
+
+For example, 0xA13DBC42908F would be entered in the following sequence:
+
+A, 1, 3, D, B, C, 4, 2, 9, 0, 8, F
+
+Remote entry of the SW shall also be provided, although the specification of that interface is beyond the scope of this Recommendation.
+
+The Scrambler shall ensure that the SW cannot be changed more than ten times in a 5-minute period and that there is a minimum of 10 seconds between changes.
+
+In this mode there will be a *CA\_descriptor* in the PMT, present at programme level, but no ECM stream. A single unique *CA\_System\_ID* is assigned to identify BISS.
+
+The *Transport\_Scrambling\_Control* bits of the Transport Packets shall be set to "10".
+
+## 8.2 CA\_descriptor
+
+The *CA\_descriptor* which must be present in the PMT to support BISS is defined in Table 1.
+
+**Table 1/J.96 – Conditional access descriptor – Mode 1**
+
+| Syntax            | No. of bits | Identifier |
+|-------------------|-------------|------------|
+| CA_descriptor() { |             |            |
+| descriptor_tag    | 8           | uimsbf     |
+| descriptor_length | 8           | uimsbf     |
+| CA_system_ID      | 16          | uimsbf     |
+| reserved          | 3           | bslbf      |
+| CA_PID            | 13          | uimsbf     |
+| }                 |             |            |
+
+### Semantics
+
+**CA\_system\_ID:** This is a 16-bit field indicating the type of CA system applicable for the associated ECM streams. The value of this field for BISS is 0x2600. See [2].
+
+**CA\_PID:** This is a 13-bit field indicating the Packet Identification Number (PID) of the Transport Stream packets that shall contain the ECM information. For BISS, no ECM information is required, so this field shall contain the value 0x1FFF.
+
+# 9 BISS Mode E – Functional requirements
+
+## 9.1 Clear Session Word
+
+The unit shall be compliant with BISS Mode 1. It shall support the insertion of a 12-character clear SW through the front panel and through a remote control interface. It shall use the SW as specified in clause 8 (BISS Mode 1).
+
+The clear SW, once entered via the user interface or remote control port, shall not be readable through any unit interface.
+
+## 9.2 Encrypted Session Word
+
+The unit shall support the insertion of ESWs through the front panel and through a remote control interface. The definition of the remote control port is outside the scope of this Recommendation.
+
+The ESW is a 16-character number that is transformed by the unit into a 12-character clear SW. The clear SW is then used by the unit to decrypt the broadcast according to clause 8 (BISS Mode 1).
+
+Once the ESW has been entered via the front panel or via the remote control interface, it shall be impossible to read it back through any unit interface.
+
+The manual entry of the ESW shall be in hexadecimal form; the 16 digits are entered with the most-significant nibble first (i.e. the left-most nibble).
+
+For example, if the ESW is 0xF76EE249BE01A286, it shall be entered in the following sequence:
+
+F, 7, 6, E, E, 2, 4, 9, B, E, 0, 1, A, 2, 8 and 6
+
+## 9.3 Decryption scheme
+
+### 9.3.1 Overview
+
+The equipment shall include the following features:
+
+- an **identifier**, denoted **ID**, comprising a 14-character hexadecimal word which shall be *injected* by the user and shall be used as the default. The injected ID is mandatory. Optionally, in addition, the supplier may *bury* an ID. In this case, the user shall actively select the buried ID.
+- a **DES decryption function**, denoted  $f()$ , as described in 9.3.3. Additional functions may be supplied but are beyond the scope of this Recommendation.
+- a **simple post-processing function**, denoted  $P()$ , as described in 9.3.4.
+
+The processing of the ESW in the unit to provide the clear SW is illustrated in Figure 1. A detailed specification of the Data Encryption Standard (DES) is outside the scope of this Recommendation.
+
+![Figure 1/J.96 – The signal processing required to produce a clear Session Word. The diagram shows the flow from ESW (64 bits) through a DES decryption function f()^-1 to produce SW' (64 bits). SW' is then processed by a Reduction block to produce SW'' (48 bits). SW'' is then processed by a post-processing function P() to produce the final Clear SW (48 bits). The process also involves ID mapping and selection. Injected ID (56 bits) and Buried ID (56 bits) are inputs to a Mapping block, which outputs a Mapped Active ID (64 bits). This Mapped Active ID is input to the DES decryption function. An Active ID selection block takes the Buried ID and outputs an Active ID selection signal to the post-processing function P().](7e670a2b556b53ea9002dfff3a420e08_img.jpg)
+
+```
+graph LR
+    ESW["ESW  
+64 bits"] --> DES["f()⁻¹ = DES"]
+    DES --> SW_prime["SW'  
+64 bits"]
+    SW_prime --> Reduction["Reduction"]
+    Reduction --> SW_double_prime["SW''  
+48 bits"]
+    SW_double_prime --> P["P()"]
+    P --> Clear_SW["Clear SW  
+48 bits"]
+    Injected_ID["Injected ID"] --> Mapping["Mapping"]
+    Buried_ID["Buried ID"] -.-> Mapping
+    Mapping --> Mapped_Active_ID["Mapped Active ID  
+64 bits"]
+    Mapped_Active_ID --> DES
+    Buried_ID --> Active_ID_selection["Active ID selection"]
+    Active_ID_selection --> P
+```
+
+J.096AMD.1  
+F9.3.1
+
+Figure 1/J.96 – The signal processing required to produce a clear Session Word. The diagram shows the flow from ESW (64 bits) through a DES decryption function f()^-1 to produce SW' (64 bits). SW' is then processed by a Reduction block to produce SW'' (48 bits). SW'' is then processed by a post-processing function P() to produce the final Clear SW (48 bits). The process also involves ID mapping and selection. Injected ID (56 bits) and Buried ID (56 bits) are inputs to a Mapping block, which outputs a Mapped Active ID (64 bits). This Mapped Active ID is input to the DES decryption function. An Active ID selection block takes the Buried ID and outputs an Active ID selection signal to the post-processing function P().
+
+Figure 1/J.96 – The signal processing required to produce a clear Session Word
+
+The mapping of the ID is a simple expansion from 56 to 64 bits, by adding an odd parity bit after every 7 bits. The reduction of the decrypted SW from 64 to 48 bits is obtained by deleting the first and last bit of each byte.
+
+After the application of the post-processing function,  $P()$ , the clear SW is obtained to feed the BISS equipment as in Mode 1.
+
+### 9.3.2 Unit identifiers
+
+This Recommendation specifies two types of identifiers for each unit.
+
+- 1) An **injected identifier** ( $ID_i$ ) which is a secret key embedded in the unit. This is ***mandatory***.
+- 2) Additionally, the manufacturer may provide a **buried identifier** ( $ID_b$ ), defined by the manufacturer and linked uniquely to the device itself. This is not mandatory, but if implemented it shall comply with this Recommendation.
+
+A user shall be able to select the identifier of his choice via the front panel and the remote control interface. The selected identifier is used as the active key to decrypt the ESW.
+
+- a) Injected ID – ***mandatory***
+
+The injected ID is a 14-character identifier that can be entered in the BISS unit by the user at any time.
+
+Units shall support the insertion of the injected ID through its front panel and through its remote control interface. There shall be no mechanism for reading back part or all of the injected ID via any unit interface.
+
+The same ID can be injected in more than one piece of equipment, e.g. for redundancy management.
+
+The manual or remote entry of the injected ID shall be in hexadecimal form; the 14 digits are entered with the most-significant nibble first (i.e. the left-most nibble).
+
+For example, if the injected ID is 0xF09A423F56738A, it shall be entered in the following sequence:
+
+F, 0, 9, A, 4, 2, 3, F, 5, 6, 7, 3, 8 and A
+
+#### b) Buried ID – optional for the supplier
+
+The buried ID is a 14-character identifier that uniquely identifies a particular unit. Buried IDs are optional.
+
+Two different units shall have a different buried ID, at least for the equipment produced by the same manufacturer. Units from different manufacturers could have the same buried ID, but that would be a fortuitous case.
+
+The manufacturer shall ensure that, without his agreement, nobody can modify the buried ID.
+
+### 9.3.3 Decryption function
+
+Units shall implement the interoperable function specified in b) below. Additional decryption functions may optionally be implemented. In this case, it shall be possible to select the decryption function via the front panel and the remote control interface. The definition of these additional functions is outside the scope of this Recommendation.
+
+The interoperable function is mandatory on all units. It uses the 64-bit ESW and the 64-bit Mapped Active ID to compute a 12-character word called SW".
+
+#### a) *Mapping*
+
+The Mapped Active ID is derived from the 56-bit Active ID by mapping the 56 Active ID bits into the upper seven bits of a sequence of 8 bytes, then the lsb of each byte is set such that the resultant byte has odd parity (see Table 2).
+
+**Table 2/J.96 – Mapping of Active ID to Mapped Active ID**
+
+| Active key bit                                                         | Mapped byte/bit | Mapped key bit |
+|------------------------------------------------------------------------|-----------------|----------------|
+| 55                                                                     | 0/7             | 63             |
+| 54                                                                     | 0/6             | 62             |
+| 53                                                                     | 0/5             | 61             |
+| 52                                                                     | 0/4             | 60             |
+| 51                                                                     | 0/3             | 59             |
+| 50                                                                     | 0/2             | 58             |
+| 49                                                                     | 0/1             | 57             |
+| Odd_parity                                                             | 0/0             | 56             |
+| 48                                                                     | 1/7             | 55             |
+| Etc.                                                                   | Etc.            | Etc.           |
+| NOTE – The above uses engineering notation: msb = bit 63, lsb = bit 0. |                 |                |
+
+#### b) *Interoperable function*
+
+The interoperable function is the simple DES algorithm used in the Electronic Codebook (ECB) mode and the decrypt state. This function is described in FIPS PUB 46-3 [3] and FIPS PUB 81 [4]. The algorithm key is the 64-bit Mapped Active ID<sup>1</sup>. The data bloc to decrypt is the ESW. Note that this Recommendation uses *engineering* notation (msb = bit 63, lsb = bit 0), while DES uses *FIPS* notation (msb = bit 1, lsb = bit 64). Hence the bit mapping is:
+
+- DES key (1 ... 64) → Mapped Active ID (63 ... 0);
+- DES data bloc (1 ... 64) → ESW (63 ... 0).
+
+The result of the decryption algorithm is defined in 64 bits and is called SW'.
+
+The mapping between SW' and SW'' is given in Table 3. This mapping simply removes the most significant and the least-significant bit of each byte. The third column of the table is the DES result, where the bits are numbered using FIPS notation.
+
+**Table 3/J.96 – Mapping between SW' and SW''**
+
+|          |         |       |
+|----------|---------|-------|
+| SW''(47) | SW'(62) | D(2)  |
+| SW''(46) | SW'(61) | D(3)  |
+| SW''(45) | SW'(60) | D(4)  |
+| SW''(44) | SW'(59) | D(5)  |
+| SW''(43) | SW'(58) | D(6)  |
+| SW''(42) | SW'(57) | D(7)  |
+| SW''(41) | SW'(54) | D(10) |
+| SW''(40) | SW'(53) | D(11) |
+| SW''(39) | SW'(52) | D(12) |
+| SW''(38) | SW'(51) | D(13) |
+| SW''(37) | SW'(50) | D(14) |
+| SW''(36) | SW'(49) | D(15) |
+| SW''(35) | SW'(46) | D(18) |
+| SW''(34) | SW'(45) | D(19) |
+| SW''(33) | SW'(44) | D(20) |
+| SW''(32) | SW'(43) | D(21) |
+| SW''(31) | SW'(42) | D(22) |
+| SW''(30) | SW'(41) | D(23) |
+| SW''(29) | SW'(38) | D(26) |
+| SW''(28) | SW'(37) | D(27) |
+| SW''(27) | SW'(36) | D(28) |
+| SW''(26) | SW'(35) | D(29) |
+| SW''(25) | SW'(34) | D(30) |
+| SW''(24) | SW'(33) | D(31) |
+
+<sup>1</sup> The DES algorithm does not use bits 8, 16, 24, 32, 40, 48, 56 and 64 of the key, numbered with the FIPS notation. Hence the useful key length is actually 56 bits, which is compatible with the exportation restrictions.
+
+**Table 3/J.96 – Mapping between SW' and SW''**
+
+|          |         |       |
+|----------|---------|-------|
+| SW''(23) | SW'(30) | D(34) |
+| SW''(22) | SW'(29) | D(35) |
+| SW''(21) | SW'(28) | D(36) |
+| SW''(20) | SW'(27) | D(37) |
+| SW''(19) | SW'(26) | D(38) |
+| SW''(18) | SW'(25) | D(39) |
+| SW''(17) | SW'(22) | D(42) |
+| SW''(16) | SW'(21) | D(43) |
+| SW''(15) | SW'(20) | D(44) |
+| SW''(14) | SW'(19) | D(45) |
+| SW''(13) | SW'(18) | D(46) |
+| SW''(12) | SW'(17) | D(47) |
+| SW''(11) | SW'(14) | D(50) |
+| SW''(10) | SW'(13) | D(51) |
+| SW''(9)  | SW'(12) | D(52) |
+| SW''(8)  | SW'(11) | D(53) |
+| SW''(7)  | SW'(10) | D(54) |
+| SW''(6)  | SW'(9)  | D(55) |
+| SW''(5)  | SW'(6)  | D(58) |
+| SW''(4)  | SW'(5)  | D(59) |
+| SW''(3)  | SW'(4)  | D(60) |
+| SW''(2)  | SW'(3)  | D(61) |
+| SW''(1)  | SW'(2)  | D(62) |
+| SW''(0)  | SW'(1)  | D(63) |
+
+### 9.3.4 Post-processing function
+
+The post-processing function  $P()$  converts SW'' into the clear SW, as shown in the example below. The conversion gives different results, depending on the type of ID used to decrypt the ESW. When the active key is the **injected ID**, function  $P()$  is the **identity function** (i.e.  $SW'' = SW$ ). If the optional **buried ID** is used, function  $P()$  consists of **rotating** the SW'' by **one bit to the right**.
+
+If  $SW'' = b_{47} b_{46} \dots b_1 b_0$
+
+$$SW = P(SW'') = \begin{cases} b_{47} b_{46} \dots b_1 b_0 & \text{If the active key is an } \mathbf{injected\ ID} \\ b_0 b_{47} b_{46} \dots b_2 b_1 & \text{If the active key is a } \mathbf{buried\ ID} \\ \text{Undefined} & \mathbf{Other\ cases} \end{cases}$$
+
+In **other** cases, the definition of  $P()$  is outside the scope of this Recommendation. It shall however have a different mathematical behaviour (i.e. it shall produce different results) than when the active key is either the *injected ID* or the *buried ID*.
+
+# Bibliography
+
+- [1] *DVB Common Scrambling Algorithm*, V. 2.0. (July 2002).  
+<http://portal.etsi.org/dvbandca/DVB/DVBINTRO.asp>
+- [2] ETSI ETR 289 (1996), Digital Video Broadcasting (DVB); Support for use of scrambling and Conditional Access (CA) within digital broadcasting systems.  
+<http://webapp.etsi.org/workprogram/SimpleSearch/QueryForm.asp>
+- [3] FIPS PUB 46-3 (1999), *Data Encryption Standard*.  
+<http://www.itl.nist.gov/fipspubs/by-num.htm>
+- [4] FIPS PUB 81 (1980), *DES Modes of Operation*.  
+<http://www.itl.nist.gov/fipspubs/by-num.htm>
+
+
+
+
+
+## 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                                                                                            |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b>                             |
+| 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
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@@ -0,0 +1,318 @@
+
+
+![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
+
+**J.98**
+
+(05/2003)
+
+SERIES J: CABLE NETWORKS AND TRANSMISSION  
+OF TELEVISION, SOUND PROGRAMME AND OTHER  
+MULTIMEDIA SIGNALS
+
+Ancillary digital services for television transmission
+
+---
+
+**Metadata requirements for video-on-demand in  
+cable networks**
+
+ITU-T Recommendation J.98
+
+---
+
+# ITU-T J-SERIES RECOMMENDATIONS
+
+## CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS
+
+|                                                                                                 |                  |
+|-------------------------------------------------------------------------------------------------|------------------|
+| General Recommendations                                                                         | J.1–J.9          |
+| General specifications for analogue sound-programme transmission                                | J.10–J.19        |
+| Performance characteristics of analogue sound-programme circuits                                | J.20–J.29        |
+| Equipment and lines used for analogue sound-programme circuits                                  | J.30–J.39        |
+| Digital encoders for analogue sound-programme signals                                           | J.40–J.49        |
+| Digital transmission of sound-programme signals                                                 | J.50–J.59        |
+| Circuits for analogue television transmission                                                   | J.60–J.69        |
+| Analogue television transmission over metallic lines and interconnection with radio-relay links | J.70–J.79        |
+| Digital transmission of television signals                                                      | J.80–J.89        |
+| <b>Ancillary digital services for television transmission</b>                                   | <b>J.90–J.99</b> |
+| Operational requirements and methods for television transmission                                | J.100–J.109      |
+| Interactive systems for digital television distribution                                         | J.110–J.129      |
+| Transport of MPEG-2 signals on packetized networks                                              | J.130–J.139      |
+| Measurement of the quality of service                                                           | J.140–J.149      |
+| Digital television distribution through local subscriber networks                               | J.150–J.159      |
+| IPCablecom                                                                                      | J.160–J.179      |
+| Miscellaneous                                                                                   | J.180–J.199      |
+| Application for Interactive Digital Television                                                  | J.200–J.209      |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+## **ITU-T Recommendation J.98**
+
+## **Metadata requirements for video-on-demand in cable networks**
+
+## **Summary**
+
+The purpose of this Recommendation is to describe requirements at the cable operator's headend for Video-on-Demand (VoD) metadata. It is envisioned that an industry standard will promote new marketing opportunities, interoperability of assets, and reduce costs to cable operators and their customers.
+
+### **Source**
+
+ITU-T Recommendation J.98 was prepared by ITU-T Study Group 9 (2001-2004) and approved under the WTSA Resolution 1 procedure on 14 May 2003.
+
+## 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 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    |
+| 2.1 Normative references.....                    | 2    |
+| 2.2 Informative references.....                  | 2    |
+| 2.3 Reference acquisition .....                  | 2    |
+| 3 Terms and definitions .....                    | 2    |
+| 4 Abbreviations and acronyms .....               | 3    |
+| 5 Metadata requirements for video-on-demand..... | 3    |
+
+
+
+## Metadata requirements for video-on-demand in cable networks
+
+# 1 Scope
+
+This Recommendation describes requirements in a cable operator's headend for Video-on-Demand (VoD) metadata. It enables a consistent level of features and offerings for VoD services that require metadata. As illustrated in Figure 1, this Recommendation, along with other metadata Recommendations to be developed, will facilitate the distribution of content assets from multiple content providers over diverse networks to cable operators to support VoD and other applications at the headend.
+
+![Diagram illustrating the distribution of content assets and scope of metadata effort. Content from Studios/Distributors (Content Provider 1, 2, 3) is delivered via Network Delivery (Satellite, Fiber, Internet, others) to the Cable Operator's Headends. The headend contains an Asset Distribution System (ADS) which connects to an Asset Management System (AMS) via an Asset Distribution Interface. The AMS is part of the VOD Servers or Application Equipment and serves Customers. A large grey arrow points to the ADS and AMS components, labeled 'Scope of Metadata Effort'.](49ee89a1d5852ab005dbbab6de09a8a6_img.jpg)
+
+The diagram shows the flow of content assets from external sources into a cable operator's headend. On the left, three boxes represent 'Content Provider 1', 'Content Provider 2', and 'Content Provider 3' under the heading 'Studios/Distributors'. Arrows from these providers point to a central cloud-like shape labeled 'Network Delivery', which is further described as 'Satellite, Fiber, Internet, others'. Below this network delivery area is the label 'Headends'. An arrow from the network delivery points into a large circle representing the 'Cable Operator (Regional Distribution Center/Headends or Headend)'. Inside the circle, an arrow points from the network delivery to a box labeled 'ADS'. From the 'ADS' box, an arrow points to a dashed vertical line labeled 'Asset Distribution Interface'. Below this interface, three boxes labeled 'AMS' are shown. Each 'AMS' box has a double-headed arrow pointing to a starburst shape labeled 'Customers'. Above the 'AMS' boxes is the text 'VOD Servers or ApplicationEqp'. A large grey arrow points upwards towards the 'ADS' and 'Asset Distribution Interface' area, with the label 'Scope of Metadata Effort' next to it. In the bottom right corner of the diagram area, the text 'J.98\_F01' is present.
+
+Diagram illustrating the distribution of content assets and scope of metadata effort. Content from Studios/Distributors (Content Provider 1, 2, 3) is delivered via Network Delivery (Satellite, Fiber, Internet, others) to the Cable Operator's Headends. The headend contains an Asset Distribution System (ADS) which connects to an Asset Management System (AMS) via an Asset Distribution Interface. The AMS is part of the VOD Servers or Application Equipment and serves Customers. A large grey arrow points to the ADS and AMS components, labeled 'Scope of Metadata Effort'.
+
+Figure 1/J.98 – Distribution of content assets and scope of metadata effort
+
+The scope of this Recommendation is limited to specific metadata tags and the interfaces that facilitate transfer of metadata and its content assets. This transfer occurs on a network from an independent provider to the cable operator via the Asset Distribution System (ADS) to whatever Asset Management System (AMS) there is residing at the cable operator's headend. This Recommendation provides a common set of metadata used to enable distribution of the content assets to an AMS, as illustrated in Figure 2. At the AMS, application-specific metadata is unwrapped to provide placement and business-rule information of the content assets. Some of the metadata may be reused in customer services, but should provide a filtering mechanism that is at the discretion of the cable operator and application server as indicated in ITU-T Rec. J.97.
+
+![](3121ebddccf183ca63bb9781be440a7e_img.jpg)
+
+|                  |                    |                     |                  |                                                  |
+|------------------|--------------------|---------------------|------------------|--------------------------------------------------|
+| MOD app metadata | Other VOD metadata | E-mail app metadata | ETV app metadata | Application metadata                             |
+| ADI metadata     |                    |                     |                  |                                                  |
+| ADI protocol     |                    |                     |                  | Asset Distribution Interface Metadata & Protocol |
+| TCP/IP           |                    |                     |                  |                                                  |
+
+J.98\_F02
+
+**Figure 2/J.98 – Metadata layers**
+
+It is important to note that metadata is not a service but enables a service like VoD to be implemented. These requirements define the creation of metadata and how it is handled in the scope of a VoD application.
+
+# 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.
+
+## 2.1 Normative references
+
+- [1] Extensible Markup Language (XML) 1.0 (Second Edition), W3C Recommendation, 6 October 2000. <http://www.w3.org/TR/2000/REC-xml-20001006>.
+
+## 2.2 Informative references
+
+- [2] CableLabs Video-on-Demand Content Specification, MD-SP-VOD-CONTENT-I01-020327.
+- [3] ITU-T Recommendation J.97 (2002), *Metadata on cable networks*.
+
+## 2.3 Reference acquisition
+
+- Cable Television Laboratories, Inc., 400 Centennial Parkway, Louisville, CO 80027; Phone +1-303-661-9100; Fax +1-303-661-9199; Internet: <http://www.cablelabs.com/>.
+- ITU Telecommunication Standardization Sector, Geneva, Switzerland; Internet: <http://www.itu.int/ITU-T/>.
+- World Wide Web Consortium, Internet: <http://www.w3.org/TR/REC-xml>.
+
+# 3 Terms and definitions
+
+This Recommendation defines the following term:
+
+**3.1 metadata:** Metadata is descriptive data associated with a content asset package or file. It may vary in depth from merely identifying the content package title or information to populate an EPG to providing a complete index of different scenes in a movie or providing business rules detailing how the content package may be displayed, copied, or sold. Separate uses for metadata
+
+have originated from the studios, distribution networks (Cable, Satellite), down to the CPE (STBs, PVRs).
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations:
+
+|      |                                       |
+|------|---------------------------------------|
+| ADI  | Asset Distribution Interface          |
+| CA   | Conditional Access                    |
+| CBR  | Constant Bit Rate                     |
+| CPE  | Customer Premises Equipment           |
+| EPG  | Electronic Programme Guide            |
+| MPEG | Motion Picture Experts Group          |
+| NTSC | National Television Systems Committee |
+| SVoD | Subscription Video-on-Demand          |
+| VoD  | Video-on-Demand                       |
+
+# 5 Metadata requirements for video-on-demand
+
+The metadata requirements for VoD are listed in Table 1.
+
+The metadata requirements are divided up into four categories for ease of classification. These categories are:
+
+- 1) Metadata for filtering/categorizing/display operations (FILT);
+- 2) Metadata for headend operations (OP);
+- 3) Metadata for playback and presentation of asset (PRES);
+- 4) Metadata for business-rule support (BUS).
+
+The following format is used for capturing the metadata requirements from existing specification and member comments.
+
+- **Requirement**  
+One or two-line description of the requirement.
+- **Additional description (optional)**  
+Additional descriptive text which may include examples to clarify the requirement in the form of an example implementation.
+- **Phasing**  
+If the requirement is not necessary in the initial implementation, a later revision or phase of the Recommendation can be targeted to support this requirement. Phase 1 is defined as supporting existing VoD services in cable networks over MPEG-2 transport.
+- **Req/Opt**  
+Specifies if it is an optional or mandated requirement to support the phase according to requirements language. This allows for a basic implementation or more advanced features or service offering supported in the same phase based upon the additional optional metadata. The field is determined to be required if at least one of the metadata tags listed is required.
+
+**Table 1/J.98 – Metadata matrix of requirements for VoD**
+
+| Req #                                                         | Requirement                                                                                          | Additional description                                                                                                                                   | Phase | Req/Opt |
+|---------------------------------------------------------------|------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------|-------|---------|
+| Current phase                                                 |                                                                                                      |                                                                                                                                                          |       |         |
+| <b>Metadata for filtering/categorizing/display operations</b> |                                                                                                      | Allows for searches, lists, selective delivery, targeting, guides.                                                                                       |       |         |
+| FILT-1                                                        | Metadata must support filtering by metadata fields.                                                  | E.g., Title, Director, Actors, Bio, Summary, run Time, box office, rental window, etc.                                                                   | 1     | Req     |
+| FILT-2                                                        | Metadata must support Parental Control filters.                                                      | This may be done by using MPAA/TV ratings and other advisories assigned to the content.                                                                  | 1     | Req     |
+| FILT-3                                                        | Metadata must support filtering based on availability of assets.                                     | Allows for VoD service to filter VoD content based on time-sensitive factors. Licensing windows are required, but the rest is optional.                  | 1     | Req     |
+| FILT-4                                                        | Metadata should provide necessary information to support display of guides.                          | To support EPG, VoD guides, title pages, and Cable guides                                                                                                | 1     | Opt     |
+| FILT-5                                                        | Metadata should support filtering by genre or category according to an cable operator specific list. | E.g., New releases, Last Chance, action/adventure, Comedy, Drama, Family, Kids, Horror, Thriller, etc.                                                   | 1     | Opt     |
+| FILT-6                                                        | Metadata may support filtering based on different foreign language-based assets.                     | E.g., support Spanish, French, Indian films                                                                                                              | 1     | Opt     |
+| FILT-7                                                        | Metadata may support filtering based on SVoD services.                                               | E.g., search by episodes of TV show                                                                                                                      | 1     | Opt     |
+| FILT-8                                                        | Metadata may support information indicating relationship between different related packages.         | SVoD TV episodes, or assets of other interests/indicates if relationship between packages.                                                               | 1     | Opt     |
+| FILT-9                                                        | Metadata may support listing of material alphabetically, numerically, or chronologically.            | Sort lists by numerical, alphabetical or time order                                                                                                      | 1     | Opt     |
+| FILT-10                                                       | Metadata may support expanded search capabilities based on fields.                                   | Allows for advanced searching based on other fields or combination of categories, e.g., director/actor combos                                            | 1     | Opt     |
+| FILT-11                                                       | Metadata should support extensible list of filterable descriptors.                                   | List of example descriptors                                                                                                                              | 1     | Opt     |
+| <b>Headend operations with metadata</b>                       |                                                                                                      | This is information required to run headend operation, maintenance, and reporting tasks.                                                                 |       |         |
+| OP-1                                                          | Cable operators must have capability to inspect, remove, change, or add to received metadata fields. | Allows for verification of metadata at headend, removal of unnecessary or unwanted information at the headend, or addition of cable-specific information | 1     | Req     |
+
+**Table 1/J.98 – Metadata matrix of requirements for VoD**
+
+| <b>Req #</b> | <b>Requirement</b>                                                                                                                                                                  | <b>Additional description</b>                                                                                                                                                                                                                                                                          | <b>Phase</b> | <b>Req/ Opt</b> |
+|--------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------|-----------------|
+| OP-2         | Information required for ingestion of package/asset or playback of asset in cable system but not included since a metadata field must have a default value or profile that is used. | E.g., encoding format might not be mentioned in a metadata field but an mpeg-2 encoding profile is the default profile used                                                                                                                                                                            | 1            | Req             |
+| OP-3         | Metadata must indicate grouping of related assets into an asset or package.                                                                                                         | This allows for a movie along with its trailer, box cover, & posters to be distributed together as one package from a content provider to headend to VoD server. It also allows for a set of titles to be distributed together as one package.                                                         | 1            | Req             |
+| OP-4         | Metadata must provide support for ingestion of package/asset into headend and its subsystems.                                                                                       | Indicates where package is to be located and what format it is in                                                                                                                                                                                                                                      | 1            | Req             |
+| OP-5         | Metadata must support unique package ID/asset ID, content ID and creation date for each package/asset and may support unique ID down to each instance.                              | Unique ID to track usage of content and where it is located. This provides interfaces to reporting, billing, and other backend functions.                                                                                                                                                              | 1            | Req             |
+| OP-6         | Each package/asset must have its own metadata associated with it.                                                                                                                   | This allows for assets to be recombined into different combinations and packages without losing metadata necessary for each asset. This information could contain description of asset, when it was created, where it can be stored, what are its playback specs, and what are its rights for playing. | 1            | Req             |
+| OP-7         | Metadata must support different types of delivery methods for packages/assets to headend.                                                                                           | This supports different types of delivery like tape, satellite, website, IP or automatic/manual input modes.                                                                                                                                                                                           | 1            | Req             |
+| OP-8         | Metadata must be able to support separate delivery of metadata and content to the headend and its subsystems.                                                                       | This allows for metadata-only types of updates via package, staged delivery, or website lookup. This also allows for retransmission of corrupted metadata without retransmitting the MPEG content.                                                                                                     | 1            | Req             |
+| OP-9         | Metadata must allow for automatic and complete quality checks of assets.                                                                                                            | E.g., checks for file corruption: this could be as little as a file size and checksum information. XML parsers can be used to reduce amount of manual QA processing.                                                                                                                                   | 1            | Req             |
+| OP-10        | Metadata must allow for asset management within the headend.                                                                                                                        | This allows for storage allotment checks, cleanup of expired content, etc.                                                                                                                                                                                                                             | 1            | Req             |
+| OP-11        | Metadata must support billing tie-ins to 3rd-party systems.                                                                                                                         | Metadata that allows content to be tied in to billing and royalty on existing and future 3rd party systems.                                                                                                                                                                                            | 1            | Req             |
+
+**Table 1/J.98 – Metadata matrix of requirements for VoD**
+
+| <b>Req #</b>                                                                 | <b>Requirement</b>                                                                                                                                    | <b>Additional description</b>                                                                                                                                                                                              | <b>Phase</b> | <b>Req/Opt</b> |
+|------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------|----------------|
+| OP-12                                                                        | Recommendations must assist in minimizing proprietary technology used by and within headend for VoD applications and headend VoD Asset management.    | This will allow VoD vendors, headend equipment, and content encoders to be interoperable.                                                                                                                                  | 1            | Req            |
+| OP-13                                                                        | Metadata in headend processes should minimize manual data entry and processing.                                                                       | This will reduce headend operations and maintenance costs.                                                                                                                                                                 | 1            | Opt            |
+| OP-14                                                                        | Metadata should allow for checks to allow for accuracy/completeness of fields including their legal aspects.                                          | E.g., to prevent a movie from being purchased but not playable, to verify playing/purchasing rights are within contract rights. Contracts rights don't have to be mentioned in metadata but should have a reference to it. | 1            | Opt            |
+| OP-15                                                                        | Metadata should support lifecycle of content.                                                                                                         | This should allow for ingestion, renewing, migration, and eventual destruction of package and/or content.                                                                                                                  | 1            | Opt            |
+| OP-16                                                                        | Metadata should indicate if content should be delivered in a secure manner.                                                                           | E.g., this can be done by encrypting the content or by encrypting in the transport layer.                                                                                                                                  | 1            | Opt            |
+| OP-17                                                                        | Implementations of requirements should consider upgrade paths to implementations of next phase requirements.                                          | Allows Cable Operators to upgrade to Phase 2 headend VoD metadata specifications without unnecessary redesign of headend/VoD equipment.                                                                                    | 1            | Opt            |
+| <b>Metadata related to playback and presentation of asset in VoD service</b> |                                                                                                                                                       | This is metadata that affects how you see or hear asset.                                                                                                                                                                   |              |                |
+| PRES-1                                                                       | Metadata must support an Audio_type and may support multiple tracks of this type.                                                                     | E.g., Dolby digital in mono, stereo, and surround sound.                                                                                                                                                                   | 1            | Req            |
+| PRES-2                                                                       | Metadata must support Preview Asset.                                                                                                                  | Allows way to preview content.                                                                                                                                                                                             | 1            | Req            |
+| PRES-3                                                                       | Metadata must support a screen format_type.                                                                                                           | E.g., standard, widescreen, letterbox                                                                                                                                                                                      | 1            | Req            |
+| PRES-4                                                                       | Metadata must support an MPEG-2 encoded video or movie asset.                                                                                         | Allows for suitable playback of VoD movie on existing cable infrastructure                                                                                                                                                 | 1            | Req            |
+| PRES-5                                                                       | Metadata must support at least single CBR encoding rate, but may expand to support multiple CBR/VBR encoding formats and rates as equipment develops. | It has to be a single rate but it could be at different bit rates to accommodate allocated channel resources for a VoD service.                                                                                            | 1            | Req            |
+| PRES-6                                                                       | Metadata should support "must see" asset option.                                                                                                      | Defines which assets must be seen during playout and prevents FF, RWD or skipping of "must see" asset                                                                                                                      | 1            | Opt            |
+| PRES-7                                                                       | Metadata may support other types of assets related to package.                                                                                        | This can be an expandable list of other types of assets like related film music videos, insertable commercials, etc.                                                                                                       | 1            | Opt            |
+
+**Table 1/J.98 – Metadata matrix of requirements for VoD**
+
+| <b>Req #</b>                               | <b>Requirement</b>                                                                                                                                                            | <b>Additional description</b>                                                                                                                                                                                                                         | <b>Phase</b> | <b>Req/Opt</b> |
+|--------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------|----------------|
+| PRES-8                                     | Metadata should enable multiple audio language tracks.                                                                                                                        | Supports a French or Spanish alternate soundtrack                                                                                                                                                                                                     | 1            | Opt            |
+| PRES-9                                     | Metadata should support alternate audio tracks.                                                                                                                               | Supports surround sound in addition to stereo, director's voiceovers to soundtracks, etc.                                                                                                                                                             | 1            | Opt            |
+| PRES-10                                    | Metadata should support graphical assets.                                                                                                                                     | Poster, Box Cover                                                                                                                                                                                                                                     | 1            | Opt            |
+| PRES-11                                    | Metadata may support foreign language UI interfaces.                                                                                                                          | Allows for different language UI interfaces                                                                                                                                                                                                           | 1            | Opt            |
+| PRES-12                                    | Metadata should support subtitle options.                                                                                                                                     |                                                                                                                                                                                                                                                       | 1            | Opt            |
+| PRES-13                                    | Metadata should inform whether closed captioning option exists for content.                                                                                                   |                                                                                                                                                                                                                                                       | 1            | Opt            |
+| PRES-14                                    | Metadata may support VoD features based upon indexing of content.                                                                                                             | Could support DVD functionalities or other implementations requiring an indexing of content                                                                                                                                                           | 1            | Opt            |
+| <b>Metadata business rule requirements</b> |                                                                                                                                                                               | Metadata related to business aspects                                                                                                                                                                                                                  |              |                |
+| BUS-1                                      | Cable operator must have the capability to filter and remove business-related metadata from informational metadata for packages given by the content provider or distributor. | This allows cable operators to use information sent separately from the received metadata for their business systems. It allows a way to flexibly adjust prices apart from the one-time price indicated by the metadata transferred with the content. | 1            | Req            |
+| BUS-2                                      | Metadata may support financial/revenue/royalty information.                                                                                                                   | This provides information for royalties, flat fees from studio, distributor, or cable operator to allow for quick ingestion of VoD package.                                                                                                           | 1            | Opt            |
+| BUS-3                                      | Metadata specification should be useable internationally.                                                                                                                     | Specification can be used in different countries.                                                                                                                                                                                                     | 1            | Opt            |
+| BUS-4                                      | Metadata should support itemized billing statements.                                                                                                                          | Customer gets a list of movies he purchased for a month with option of not listing adult content.                                                                                                                                                     | 1            | Opt            |
+| BUS-5                                      | Metadata should indicate at what point a played asset is purchased.                                                                                                           | To prevent previewing of whole movie without purchasing it                                                                                                                                                                                            | 1            | Opt            |
+| BUS-6                                      | Metadata should support rights on purchase viewing.                                                                                                                           | Makes sure any reconfigurable services do not violate rights file. This may be a conditional access, link security, or content security.                                                                                                              | 1            | Opt            |
+| BUS-7                                      | Metadata may support feature film content ratio based on language, country of origin, language and ethnicity.                                                                 | E.g., verify that content offered meets CRTc film ratios                                                                                                                                                                                              | 1            | Opt            |
+
+
+
+
+
+## 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                                                                                            |
+| <b>Series J</b> | <b>Cable networks and transmission of television, sound programme and other multimedia signals</b>                             |
+| 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