1、 International Telecommunication Union ITU-T J.173TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/2005) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS IPCablecom IPCablecom embedded MTA primary line support ITU-T Recommendation J.173 ITU-T R
2、ec. J.173 (11/2005) i ITU-T Recommendation J.173 IPCablecom embedded MTA primary line support Summary This Recommendation defines the embedded MTA (E-MTA) requirements for the analogue interface and for powering of the E-MTA. An embedded MTA is a Cable Modem (CM) integrated with an IPCablecom Media
3、Terminal Adapter (MTA). The purpose of this Recommendation is to define a set of requirements that will enable a service that is sufficiently reliable to meet a consumer expectation of essentially constant availability, including, availability during power failure at the customers premises, and (ass
4、uming the service is used to connect to the PSTN), access to emergency services. Source ITU-T Recommendation J.173 was approved on 29 November 2005 by ITU-T Study Group 9 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. J.173 (11/2005) FOREWORD The International Telecommunicat
5、ion 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 vi
6、ew 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 Recommenda
7、tions is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for concise
8、ness 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
9、 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. INTE
10、LLECTUAL 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, w
11、hether 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
12、 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. ITU-T Rec. J.173 (11/2
13、005) iii 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, acronyms and conventions. 2 4.1 Abbreviations and acronyms 2 4.2 Conventions 2 5 Introduction 3 5.1 Media Terminal Adapter (MTA) 3 6 E-MTA monitoring
14、requirements. 4 6.1 E-MTA alarms 4 6.2 E-MTA telemetry . 5 7 E-MTA power requirements. 6 7.1 Power considerations 6 7.2 Typical E-MTA traffic model 7 7.3 Power passing tap limitations. 7 7.4 Average power calculations . 7 7.5 Power factor considerations . 7 7.6 E-MTA average power requirements . 8 7
15、.7 Service requirements under AC fail conditions 8 7.8 Power source compatibility 8 7.9 Network powering 8 7.10 Local powering with battery backup 9 8 MTA analog port requirements 9 8.1 Loop start signalling. 10 8.2 General supervision 10 8.3 General ringing. 10 8.4 Voice grade analog transmission 1
16、1 Appendix I Typical E-MTA traffic model 12 Appendix II Analog interface values for North America . 12 II.1 Loop start signalling. 13 II.2 General supervision 14 II.3 General ringing. 15 II.4 Voice grade analog transmission 16 BIBLIOGRAPHY 18 ITU-T Rec. J.173 (11/2005) 1 ITU-T Recommendation J.173 I
17、PCablecom embedded MTA primary line support 1 Scope This Recommendation defines the embedded MTA (E-MTA) requirements for the analogue interface and for powering of the E-MTA. An embedded MTA is a Cable Modem (CM) integrated with an IPCablecom Media Terminal Adapter (MTA). The purpose of this Recomm
18、endation is to define a set of requirements that will enable a service that is sufficiently reliable to meet a consumer expectation of essentially constant availability, including, availability during power failure at the customers premises, and (assuming the service is used to connect to the PSTN),
19、 access to emergency services. 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 Rec
20、ommendations 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 regular
21、ly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Recommendation J.161 (2001), Audio codec requirements for the provision of bidirectional audio service over cable television networks using cable mo
22、dems. ITU-T Recommendation J.162 (2005), Network call signalling protocol for the delivery of time-critical services over cable television networks using cable modems. ITU-T Recommendation J.172 (2005), IPCablecom management event mechanism. 2.2 Informative references ITU-T Recommendation J.160 (200
23、5), Architectural framework for the delivery of time-critical services over cable television networks using cable modems. 3 Terms and definitions This Recommendation defines the following terms: 3.1 E-MTA: Term used in this Recommendation generically representing the CM and MTA combination. This cou
24、ld be an embedded MTA or a stand-alone MTA. 3.2 Media Terminal Adapter (MTA): An MTA is an IPCablecom client that can be attached to a CM (stand-alone) or integrated with a CM (embedded) that supports POTS. 2 ITU-T Rec. J.173 (11/2005) 4 Abbreviations, acronyms and conventions 4.1 Abbreviations and
25、acronyms This Recommendation uses the following abbreviations and acronyms: A/D Analog to Digital converter AN Access Node CM Cable Modem CMS Call Management Server CPE Customer Premises Equipment E-MTA Embedded MTA HFC Hybrid Fibre Coax MTA Media Terminal Adapter NCS Network Call Signalling (the IP
26、Cablecom MGCP profile used for controlling calls) POTS Plain Old Telephone Service PSTN Public Switched Telephone Network SNMP Simple Network Management Protocol UPS Uninterruptible Power Supply 4.2 Conventions If this Recommendation is implemented, the key words “MUST“ and “SHALL“ as well as “REQUI
27、RED“ are to be interpreted as indicating a mandatory aspect of this Recommendation. The key words indicating a certain level of significance of a particular requirement that are used throughout this Recommendation are summarized as follows: “MUST“ This word or the adjective “REQUIRED“ means that the
28、 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 f
29、ull 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 understoo
30、d 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,
31、 for example; another vendor may omit the same item. ITU-T Rec. J.173 (11/2005) 3 5 Introduction This Recommendation covers requirements for the E-MTA necessary to support primary line service. It is the intention of this Recommendation to address requirements only for the E-MTA. The E-MTA is define
32、d as an IPCablecom MTA integrated with a cable modem. See 5.1 for a complete description of the E-MTA. The service referred to in this Recommendation is voice-grade communications, including communications with stations on the public switched telephone network (PSTN). “Primary line service“ refers t
33、o service sufficiently reliable to meet a consumer expectation of essentially constant availability, including, specifically, availability during power failure at the customers premises, and (assuming the service is used to connect to the PSTN), access to emergency services. To enable support for re
34、liable service, three E-MTA interfaces have been identified: 1) powering the E-MTA; 2) telemetry support; and 3) the analog POTS interface. Powering the E-MTA is critical for the service to function during periods when utility power fails. Consequently, the power consumption characteristics of the E
35、-MTA will enable service providers to offer alternate powering techniques. Telemetry support enables the service provider to remotely monitor the status of the E-MTA. The first application of telemetry enables remote monitoring of the E-MTA power source. The analog POTS interface requirements ensure
36、 that CPE that meets telephone industry interoperability requirements (normal telephones, answering machines, etc.) will also operate in the IPCablecom environment. Note that the voice-grade analog transmission requirements are dependent on the compression algorithm utilized to transport the packeti
37、zed voice signal in the IPCablecom architecture. These requirements are derived from existing PSTN requirements that are based on a full 64 kbit/s voice channel. Therefore, the requirements specified are relevant only for the G.711 audio codec. Other audio codec compression algorithms specified by I
38、TU-T Rec. J.161 are not currently addressed in this Recommendation. Note also that the telemetry interface specified in this Recommendation is between the E-MTA and an external local uninterruptible power supply (UPS). The UPS itself is not within the scope of this Recommendation, so specific requir
39、ements for the UPS are not included here. Nonetheless, requirements for the E-MTA telemetry interface may have certain design implications on the UPS. 5.1 Media Terminal Adapter (MTA) An MTA is an IPCablecom client device that contains a subscriber-side interface to the subscribers CPE (e.g., teleph
40、one) and a network-side signalling interface to call control elements in the network (e.g., Call Management Server (CMS). An MTA provides codecs and all signalling and encapsulation functions required for media transport and call signalling. MTAs reside at the customer site and are connected to othe
41、r IPCablecom network elements via the HFC access network (ITU-T Recs J.112 or J.122). IPCablecom MTAs are required to support the Network Call Signalling (NCS) protocol. IPCablecom only defines support for an embedded MTA. An embedded MTA (E-MTA) is a single hardware device that incorporates a J.112
42、/J.122 cable modem as well as an IPCablecom MTA component. Figure 1 shows a representative functional diagram of an embedded MTA. Additional MTA functionality and requirements are further defined in ITU-T Rec. J.160. 4 ITU-T Rec. J.173 (11/2005) Figure 1/J.173 Embedded MTA 6 E-MTA monitoring require
43、ments The E-MTA is a critical element in the IPCablecom architecture. It provides the customers interface to the service providers network and is located outside the service providers “headend“. As such, it is critical that the operational status of the E-MTA be monitored in order to provide the qui
44、ckest information to the service provider. This clause details the critical monitoring requirements of the E-MTA. 6.1 E-MTA alarms The E-MTA functions as the customer premises network interface to the IPCablecom network and thus enables service to the customer. If the E-MTA fails and is not capable
45、of providing the intended service, the service provider will need to know about this condition quickly (and preferably before the customer). The minimum goal of fault management should be to isolate failures to a field replaceable unit. This enables the service provider to confidently dispatch servi
46、ce personnel with the appropriate equipment necessary to repair the problem in the least amount of time (i.e., minimize MTTR). Since the MTA is embedded, or integrated with the CM, the E-MTA can be considered a field replaceable unit. 6.1.1 CM failures The CM provides the critical connection between
47、 the MTA and the IPCablecom/J.112 network. A CM failure will affect the availability of the service. IPCablecom service will rely on the CM failure detection mechanisms. In this Recommendation, ITU-T Recs J.112/J.122 refer to events that the CM must detect as well as events the CMTS must detect. 6.1
48、.2 MTA failures The minimum MTA monitoring MUST utilize the CM failure detection mechanisms since the CM and MTA are integrated together. ITU-T Rec. J.173 (11/2005) 5 Additional MTA monitoring mechanisms MAY be developed but are not defined in this Recommendation. For example, the E-MTA may include
49、internal on-line diagnostics utilized to detect vendor-specific events. 6.2 E-MTA telemetry The telemetry feature provides the ability for the E-MTA to transmit alarm information to the headend. The alarm information could reflect status of the E-MTA itself or of a supporting device connected to the E-MTA. One powering option of the E-MTA is local power with uninterruptible power supply (UPS) battery backup. Maintaining constant power at the E-MTA is important to providing service. For example, an operator may want the service to continue to function when the comme
