1、 International Telecommunication Union ITU-T J.171.2TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (11/2005) SERIES J: CABLE NETWORKS AND TRANSMISSION OF TELEVISION, SOUND PROGRAMME AND OTHER MULTIMEDIA SIGNALS IPCablecom IPCablecom trunking gateway control protocol (TGCP): Profile 2 ITU-T Recommen
2、dation J.171.2 ITU-T Rec. J.171.2 (11/2005) i ITU-T Recommendation J.171.2 IPCablecom trunking gateway control protocol (TGCP): Profile 2 Summary This Recommendation specifies the Profile 2 referenced in ITU-T Rec. J.171.0. This Recommendation specifies a H.248 protocol profile (ITU-T Rec. H.248.1,
3、version 2 (05/2002) for controlling media gateways between cable networks and the PSTN. This profile is known as Trunking Gateway Control Protocol (TGCP) Profile 2 version 1. Profile 1 is specified in ITU-T Rec. J.171.1. Source ITU-T Recommendation J.171.2 was approved on 29 November 2005 by ITU-T S
4、tudy Group 9 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. J.171.2 (11/2005) 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 p
5、ermanent 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, esta
6、blishes 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-Ts purview, the necessary st
7、andards 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 R
8、ecommendation 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
9、 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
10、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 r
11、eceived 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 reser
12、ved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. J.171.2 (11/2005) iii CONTENTS Page 1 Scope 1 2 References. 1 2.1 Normative references 1 2.2 Informative references 1 3 Definitions 2 4 Abbreviations and acronyms 2 5
13、General items 2 5.1 Architectural assumptions 2 5.2 Profile definition. 3 5.3 Support of packages . 3 5.4 Compatibility rules . 3 5.5 Naming conventions. 3 5.6 Topology descriptor 4 5.7 Multiplex descriptor . 4 5.8 Transaction timers and retransmission thresholds 4 5.9 Transport. 5 5.10 Service chan
14、ge procedures . 5 5.11 Security. 5 5.12 Encoding. 5 6 Use of SDP . 5 6.1 Protocol version (v=) 6 6.2 Origin (o=) 6 6.3 Session name (s=). 7 6.4 Session and media information (i=) . 7 6.5 URI (u=) . 8 6.6 E-mail address and phone number (e=, p=) . 8 6.7 Connection data (c=) 8 6.8 Bandwidth (b=). 9 6.
15、9 Time, repeat times and time zones (t=, r=, z=). 9 6.10 Encryption keys 10 6.11 Attributes (a=) 10 6.12 Media announcements (m=). 13 7 Timestamp 14 8 Digitmap . 14 Annex A ISUP trunk tones generator Package for ITU-T Rec. H.248. 15 ITU-T Rec. J.171.2 (11/2005) 1 ITU-T Recommendation J.171.2 IPCable
16、com trunking gateway control protocol (TGCP): Profile 2 1 Scope This Recommendation specifies the Profile 2 referenced in ITU-T Rec. J.171.0. This Recommendation specifies a H.248 protocol (ITU-T Rec. H.248.1, version 2 (05/2002) profile for controlling media gateways between cable networks and the
17、PSTN. This profile is known as Trunking Gateway Control Protocol (TGCP) Profile 2 version 1. Profile 1 is specified in ITU-T Rec. J.171.1. 2 References 2.1 Normative references The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitu
18、te 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 Recom
19、mendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T Recommendation H.248.1 v2 (2002), Gatewa
20、y control protocol: Version 2. ITU-T Recommendation H.248.2 (2005), Gateway control protocol: Facsimile, text conversation and call discrimination packages. ITU-T Recommendation J.161 (2001), Audio codec requirements for the provision of bidirectional audio service over cable television networks usi
21、ng cable modems. ITU-T Recommendation J.170 (2005), IPCablecom security specification. IETF RFC 1035 (1987), Domain names Implementation and specification. IETF RFC 2045 (1996), Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies. IETF RFC 2234 (1997), Augmented
22、BNF for Syntax Specifications: ABNF. IETF RFC 2327 (1998), SDP: Session Description Protocol. 2.2 Informative references ITU-T Recommendation J.160 (2005), Architectural framework for the delivery of time-critical services over cable television networks using cable modems. ITU-T Recommendation J.171
23、.0 (2005), IPCablecom trunking gateway control protocol (TGCP): Profiles overview. ITU-T Recommendation J.171.1 (2005), IPCablecom trunking gateway control protocol (TGCP): Profile 1. IETF RFC 1889 (1996), RTP: A Transport Protocol for Real-Time Applications. IETF RFC 1890 (1996), RTP Profile for Au
24、dio and Video Conferences with Minimal Control. 2 ITU-T Rec. J.171.2 (11/2005) 3 Definitions This Recommendation defines no new terms. 4 Abbreviations and acronyms This Recommendation uses the following abbreviations: ASCII American Standard Code for Information Interchange AVP Audio Visual Profile
25、DNS Domain Name System IANA Internet Assigned Numbers Authority IP Internet Protocol IPSec Internet Protocol Security ISUP ISDN User Part MG Media Gateway MGC Media Gateway Controller MGCP Media Gateway Control Protocol MIB Management Information Base MTA Multimedia Terminal Adapter MWD Maximum Wait
26、ing Delay NCS Network-based Call Signalling NTP Network Time Protocol PSTN Public Switched Telephone Network QoS Quality of Service RTCP RTP Control Protocol RTO Retransmission Timeout RTP Real-Time Transport Protocol SDP Session Description Protocol SG Signalling Gateway SPI Security Parameters Ind
27、ex TGCP Trunking Gateway Control Protocol UDP User Datagram Protocol URI Uniform Resource Identifier 5 General items 5.1 Architectural assumptions This Recommendation applies to the interface between a Media Gateway Controller and a Media Gateway sitting at the boundary between an IPCablecom network
28、 and the PSTN. The overall architecture for interconnecting IPCablecom networks with the PSTN is described in ITU-T Rec. J.160. ITU-T Rec. J.171.2 (11/2005) 3 5.2 Profile definition This profile shall be entitled “TGCP_H248“. The version number shall be “1“. This name shall be returned by conforming
29、 gateways when sending a ServiceChange command as part of the initial registration of the MG. This profile is applicable to version 2 of ITU-T Rec. H.248.1 (05/2002). 5.3 Support of packages 5.3.1 Mandatory packages The following packages shall be supported: Table 1/J.171.2 Mandatory packages Packag
30、e name Id Version Defined in Generic g 1 ITU-T Rec. H.248.1 version 2 (05/2002), Annex E Base Root root 1 ITU-T Rec. H.248.1 version 2 (05/2002), Annex E Continuity ct 1 ITU-T Rec. H.248.1 version 2 (05/2002), Annex E Network nt ITU-T Rec. H.248.1 version 2 (05/2002), Annex E TDM Circuit tdmc 1 ITU-
31、T Rec. H.248.1 version 2 (05/2002), Annex E ISUP Trunk Tones Generator isuptn 1 See Annex A 5.3.2 Conditional packages The following packages shall be supported under the specified conditions: Table 2/J.171.2 Conditional packages Package name Id Version Defined in Condition Fax/TextPhone/Modem Tones
32、 Detection ftmd 1 ITU-T Rec. H.248.2 Some of the codecs supported by the cable networks are not transparent to fax, modem or textphone signals. 5.4 Compatibility rules This profile is based on ITU-T Rec. H.248.1 version 2 (05/2002). The compatibility rules for packages, signals, events, properties a
33、nd statistics and the H.248 protocol are defined in ITU-T Rec. H.248.1 version 2 (05/2002). 5.5 Naming conventions 5.5.1 MG and MGC names MG and MGC names shall be in the form of a domain name IETF RFC 1035. An example MGC name is: . 5.5.2 Termination identifiers 5.5.2.1 Physical termination identif
34、iers Termination identifiers representing physical trunks or trunks groups shall adhere to the following conventions: Termination names shall consist of a series of terms each separated by a slash (“/“) that describe the physical hierarchy within the gateway: ds/_/_/ 4 ITU-T Rec. J.171.2 (11/2005) T
35、he first term (ds) identifies the termination naming scheme used and the basic termination type. The last term is a decimal number that indicates the channel number at the lowest level of the hierarchy. Intermediate terms between the first term (ds) and last term (channel number) represent intermedi
36、ate levels of the hierarchy and consist of and separated by an underscore (“_“) where: the identifies the particular hierarchy level. Values of presently defined are: “s“, “su“, “oc3“, “ds3“, “e3“, “ds2“, “e2“, “ds1“, “e1“ where “s“ indicates a slot number and “su“ indicates a sub-unit within a slot
37、. Other values representing physical hierarchy levels that have not been included in this list but which follow the same basic naming rules will also be allowed; the is a decimal number which is used to reference a particular instance of a at that level of the hierarchy. The number of levels and nam
38、ing of those levels is based on the physical hierarchy within the media gateway, as illustrated by the following examples: a Media Gateway that has some number of DS1 interfaces: ds/ds1_#/# a Media Gateway that has some number of OC3 interfaces, that contain channelized DS3 and DS1 hierarchies: ds/o
39、c3_#/ds3_#/ds1_#/# a Media Gateway that contains some number of slots with each slot having some number of DS3 interfaces: ds/s_#/ds3_#/ds1_#/# Some terminations may not contain all possible levels of a hierarchy; however, all levels supported by a given termination are contained in the termination
40、naming scheme. For example, a DS3 without DS1 framing could be represented by the following naming scheme: ds/s_#/ds3_#/# However, a DS3 with DS1 framing could not be represented by that naming scheme. 5.6 Topology descriptor A Gateway conforming to this Recommendation need not implement the topolog
41、y descriptor. MGCs that expect to control gateways conforming to this Recommendation shall not assume that topology descriptor is supported. 5.7 Multiplex descriptor A Gateway conforming to this Recommendation need not implement the mux descriptor. MGCs that expect to control gateways conforming to
42、this Recommendation shall not assume that mux descriptor is supported. 5.8 Transaction timers and retransmission thresholds All transaction timers as specified in ITU-T Rec. H.248.1 version 2 (05/2002) shall be supported here. For this profile of H.248, the following default values are specified in
43、relation to H.248 transaction timers and retransmission thresholds: LONG-TIMER: This shall have a default value of 30 seconds. ITU-T Rec. J.171.2 (11/2005) 5 T-MAX: This shall have a default value of 20 seconds. MAX-1: This shall have a default value of 5 retransmissions. MAX-2: This shall have a de
44、fault value of 7 retransmissions. NOTE In all cases where this Recommendation specifies defaults, it should be noted that all of the properties of the timer or retransmission thresholds described within H.248 itself remain in force. In particular, this means that if H.248 states that a timer or retr
45、ansmission threshold may be later configured through provisioning, then this behaviour is also allowed. 5.9 Transport Media Gateways shall implement UDP/ALF. 5.10 Service change procedures The Media Gateway shall allow one primary and one or more secondary MGCs to be provisioned for registration. 5.
46、11 Security Media Gateways and Media Gateway Controllers shall implement security as described in the IPCablecom security specification (ITU-T Rec. J.170). 5.12 Encoding Conforming Media Gateways and Media Gateway Controllers shall support text encoding. 6 Use of SDP The Local and Remote descriptors
47、 use SDP with certain modifications in the MGC to MG direction as specified in ITU-T Rec. H.248.1 version 2 (05/2002). Furthermore, trunking gateways conforming to this profile may make certain simplifying assumptions about the session descriptions as specified in the following. SDP usage depends on
48、 the type of session, as specified in the “media“ parameter. This Recommendation only supports media of type “audio“. The SDP profile provided describes the use of the session description protocol in TGCP. The general description and explanation of the individual parameters can be found in IETF RFC
49、2327; however, below we detail what values are sent in the MGC to MG direction and what values are sent in the MG to MGC direction. Where the MG may choose a value of a particular parameter, wildcards are used. The use of wildcards shall be in accordance with H.248.1 procedures. Due to the particular function of the trunking gateway within the IPCablecom system, the Remote descriptor is only sent in the MGC to MG direction once SDP has been received from the remote end of the call. If no SDP has yet
