1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU TA25 (02/98) SERIES T: TERMINALS FOR TELEMATIC SERVICES Multipoint communication service protocol spec if ication ITU-T Recommendation T. 125 (Previously CCIlT Recommendation) RECMN T-325-ENGL 3998 W 4862593
2、0b539b bT3 W ITU-T T-SERIES RECOMMENDATIONS TERMINALS FOR TELEMATIC SERVICES For further details, please refer to iTU-T List of Recommendations. ITU-T RECOMMENDATION TA25 MULTIPOINT COMMUNICATION SERVICE PROTOCOL SPECIFICATION Summary This Recommendation defines a protocol operating through the hier
3、archy of a multipoint communication domain. It specifies the format of protocol messages and procedures governing their exchange over a set of transport connections. The purpose of the protocol is to implement the Multipoint Communication Service defined by Recommendation T. 122. Annex A defines a p
4、rotocol allowing the use of multicast network services in a T.120 conference. It does this by performing data routing as part of T.125. Once it assumes responsibility for routing, it will use multicast whenever possible. This Annex handles sub-optimal networks by testing multicast pathways before de
5、pending on them. In the event that multicast does not work at some point within the conference, unicast is used in its place. This Annex is independent of the networks on which it is used. All issues that are specific to a given network are handled by the protocol stacks that lie beneath this protoc
6、ol. The following changes have been incorporated into this version of the Recommendation: - - - - - the MAP protocol has been incorporated as Annex A; MCS Protocol version 3 is specified; Extended-Parameter MCSPDUs have been added; Capabilities-Notijication MCSPDUs have been added; fields were added
7、 to the Send-Data and Uniform-Send-Data MCSPDUs to support changes to Recommendation T. 122; minor changes have been made to the document format. - Source ITU-T Recommendation T.125 was revised by ITU-T Study Group 16 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 6th
8、of February 1998. STDmITU-T RECMN Te125-ENGL 1778 W 48b259L Ob5L998 47b 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-
9、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 st
10、udy 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-Ts purview, the neces
11、sary standards are prepared on a collaborative basis with IS0 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 t
12、he 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 outs
13、ide 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 th
14、e latest information and are therefore strongly urged to consult the TSB patent database. O 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 writi
15、ng from the ITU. 11 Recommendation T.125 (02/98) STDmITU-T RECMN T.125-ENGL 1998 m 4862591 Ob53999 302 m CONTENTS Page 1 Scope 2 References 3 Definitions 4 Abbreviations . 5 5.1 5.2 Overview of the MCS protocol Model of the MCS layer . Services provided by the MCS layer 5.2.1 MAP layer services . Se
16、rvices assumed from the transport layer . Functions of the MCS layer 5.4.1 Domain management . 5.4.2 Channel management 5.4.3 Data transfer 5.4.4 Token management . 5.4.5 Capabilities notification 5.5 Hierarchical processing 5.6 Domain parameters . 5.7 Extended parameters . 5.3 5.4 6 Use of the tran
17、sport service 6.1 Model of the transport service 6.2 Use of multiple connections . 6.3 Transport connection release 7 Structure of Version 2 MCSPDUs . 8 Structure of Version 3 MCSPDUs . 9 Encoding of MCSPDUs . 10 Routing of MCSPDUs 1 O . 1 Connect and extended parameters MCSPDUs . 10.2 Domain MCSPDU
18、s 11 Meaning of MCSPDUs . 1 1. 1 Connect-Initial 1 1.2 Connect-Response 1 1.3 Connect-Additional Recommendation T.125 (02/98) 1 2 4 4 4 5 5 5 5 6 8 8 9 9 9 11 12 12 12 13 14 14 24 37 37 37 39 42 42 43 44 . 111 . - . STD-ITU-T RECMN T-125-ENGL 1998 48b259L Ob52000 722 11.4 11.5 11.6 11.7 11.8 11.9 11
19、.10 11.11 11.12 11.13 11.14 11.15 11.16 11.17 11.18 11.19 1 1.20 11.21 1 i . 22 1 1.23 11.24 11.25 11.26 11.27 1 1.28 11.29 1 1.30 11.31 11.32 11.33 11.34 11.35 11.36 11.37 11.38 Connect-Result . Extended-Parameters-Propose Extended-Parameters-Accept . ErectDomainRequest MergeChannelsRequest MergeCh
20、annelsConfirm . MergeTokensRequest . PlumbDomainIndication . PurgeChannelsIndication MergeTokensConfirm PurgeTokensIndication . DisconnectProviderUltimahun . Rej ectMCSPDUU1timatu.m AttachUserRequest . AttachUserConfm DetachUserRequest DetachUserIndication . Channel JoinRequest . ChannelJoinConfirm
21、. C hannelLeaveRequest ChannelConveneRequest ChannelConveneConfim . ChannelDisbandRequest . ChannelDisbandIndication . ChannelAdmitRequest ChannelAdmitIndication ChannelExpelRequest . C hannelExpelIndication . SendDataRequest SendDataIndication UniformSendDataRequest UniformSendDataIndication . Toke
22、nGrabRequest . TokenGrabConfirm TokenInhibitRequest Page 44 45 45 45 46 47 48 48 49 50 51 51 51 52 52 52 53 54 55 55 56 56 56 57 57 58 58 58 59 60 61 62 62 63 63 iv Recommendation T.125 (02/98) - 11.39 11.40 11.41 1 1.42 1 1.43 11.44 11.45 11.46 1 1.47 1 1.48 11.49 11.50 11.51 12 12.1 12.2 12.3 13 1
23、3.1 13.2 13.3 13.4 13.5 13.6 13.7 13.8 13.9 TokenInhibitConfirm TokenGiveRequest . TokenGiveIndication TokenGiveResponse . TokenGiveConfi nn . TokenPleaseRequest . TokenPleaseIndication . TokenReleaseRequest . TokenReleaseConfm TokenTestRequest TokenTestConfirm . CapabilitiesNotificationRequest . 1
24、1.50.1 Request Capability CapabilitiesNotificationIndication . 1 1.5 1 . 1 Indication Capability . MCS provider information base . Hierarchical replication Channel idormation . Token information Elements of procedure MCSPDU sequencing . Input flow control . Throughput enforcement Domain configuratio
25、n . Domain merger . Domain disconnection Channel id allocation Token status Capabilities Notification . 13.9.1 Capability IDS . 13.9.2 Version 3 Summits 13.9.3 Rules of capability selection . 13.9.4 Establishing the V3 summit provider 13.9.5 Expanding the V3 summit . 13.9.6 Processing PDUs at a leaf
26、 node . Recommendation T.125 (02/98) Page 64 64 64 65 66 66 66 67 67 67 68 68 69 69 69 70 70 71 72 74 74 75 75 77 77 79 80. 80 81 81 81 82 83 83 83 V STD-ITU-T RECMN T-125-ENGL I1998 4862591 Ob52002 5T5 m 13.9.7 Processing PDUs at an intermediate node . 13.1 O Protocol version arbitration 13.1 1 Pro
27、tocol version interoperability Annex A . Multicast adaptation protocol A.l Scope A.2 Normative references A.3 Definitions A.4 Abbreviations . AS Overview AS . 1 The use of multicast AS . 2 Multicast islands AS . 3 Multicast group providers . A.5.4 Data ordering . A.5.5 Use of multicast and unreliabl
28、e unicast . A.6 Use of MAP A.6.1 Domain management . A.6.2 Channel management A.6.3 Data transfer A.6.4 Token management . A.7 Use of transport protocols A.7.1 Unicast transport protocols A.7.2 Multicast transport protocols . A.7.3 Local information A.8 Protocol specification . A.8.1 Establishing th
29、e initial reliable unicast connection . A.8.2 Arbitrating transport protocols A.8.3 Allocating and distributing multicast groups A.8.4 Managing multicast data traffic (self-tuning) A.8.5 Giving up on multicast A.8.6 Removing multicast groups . A.9 MAPPDU descriptions . A.9.1 MAPConnectRequest A.9.2
30、MAPConnectConfirm . A.9.3 MAPDisconnectRequest . A.9.4 MAPDisconnectCon firm . A.9.5 MAPArbitrateProtocolsRequest Page 84 88 88 89 89 90 91 92 92 93 93 95 95 96 96 96 97 97 99 99 100 102 103 104 104 105 108 109 111 111 113 113 114 115 115 115 vi Recommendation T.125 (02/98) . STD-ITU-T RECflN T.125-
31、ENGL 1998 m 4862591 Ob52003 431 m A.9.6 MAPArbitrateProtocolsCo nfimi . A.9.7 MAPData . A.9.8 MAPAddGroupRequest A.9.9 MAPRemoveGroupRequest A.9.10 MAPDisableUnicastReqst . A.9.11 MAPEnableUnicastRequest A.9.12 MAPEnableUnicastCodirm . A.9.13 MAPDisableMulticastRequest A.9.14 MAPDisab1eMulticastConf
32、h-m . A.9.15 MAPEnableMulticastRequest . A.9.16 MAPSequenceNumber MAPPDU ASN.l Definition A . 10 Page 118 120 122 124 124 125 125 126 126 126 127 127 Recommendation T.125 (02/98) vii - - STD-ITU-T RECMN TmL25-ENGL 1998 9 48b259L Ob52004 378 = 1 Recommandation T.125 MULTIPOINT COMMUNICATION SERVICE P
33、ROTOCOL SPECIFICATION (revised in 1998) 1 Scope This Recommendation specifies: a) b) The procedures are defined in terms of: a) the interactions between peer MCS providers through the exchange of MCS protocol data units; b the interactions between an MCS provider and MCS users through the exchange o
34、f MCS primitives; c) the interactions between an MCS provider and a transport service provider through the exchange of transport service primitives. These procedures are applicable to instances of multipeer communication among systems that support MCS and wish to interconnect in an open systems envi
35、ronment. procedures for a single protocol for the transfer of data and control information from one MCS provider to a peer MCS provider; the structure and encoding of the MCS protocol data units used for the transfer of data and control information. 2 References The following Recommendations and oth
36、er 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 encour
37、aged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. - ITU-T Recommendation T. 122 (1 998), Multipoint Communication Service - Service defnition. I
38、TU-T Recommendation T. 123 (1 996), Network speciJic data protocol stach for multimedia conferencing. ITU-T Recommendation X.200 (1 994) I ISOAEC 7498-1 : 1994, Information technology - Open Systems Interconnection - Basic reference model: The basic model. ITU-T Recommendation X.214 (1995) I ISO/IEC
39、 8072: 1996, Information technology - Open Systems Interconnection - Transport service definition. ITU-T Recommendation X.680 (1997) I ISOIEC 8824-1: 1998, Information technology - Abstract Syntax Notation One (ASN. I) - Specification of basic notation. ITU-T Recommendation X.690 (1997) I ISO/IEC 88
40、25-1:1998, Information technology - ASN I encoding rules: Specijication of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER). - - - - - Recommendation T.125 (02/98) 1 - STD-ITU-T RECMN TmL25-ENGL 1998 m 4b259L Ob52005 204 m - ITU-T Recommendation X.691
41、 (1997) I ISO/IEC 8825-2: 1998, Information technoIogy - ASN. I encoding rules - SpeciJication of Packed Encoding Rules (PER). 3 Definitions NOTE - These definitions make use of the abbreviations defined in clause 4. This Recommendation is based on the concepts developed in Recommendation X.200 and
42、makes use of the following terms defined therein: a) flow control; b) reassembling; c recombining; d) segmenting; e sequencing; 0 splitting; g) transfer syntax; h) transport connection; i transport connection endpoint identifier; j transport service; k) transport service access point; 1) m) transpor
43、t service data unit. transport service access point address; This Recommendation is also based on the concepts developed in Recommendation T.122 and makes use of the following terms defined therein: a) control MCSAP; b) MCS attachment; c) MCS channel; d) MCS connection; e MCS domain; f) MCS domain s
44、elector; g MCS private channel; h MCS private channel manager; i) MCS provider; j MCS service access point; k) MCS user; 1) MCS user id; m) top MCS provider. For the purposes of this Recommendation, the following definitions apply. 3.1 MCS service data unit: An amount of MCS user data whose identity
45、 is preserved during the transfer from transmitter to receivers. Specifically, the content of one MCS-SEND-DATA request or one MCS-UNIFORM-SEND-DATA request. 3.2 MCS interface data unit: The unit of information transferred across an MCSAP between an MCS user and anMCS provider in a single interactio
46、n. Each MCS interface data unit contains interface control information and may also contain all or part of an MCS service data unit. 3.3 MCS protocol data unit: A Unit of information exchanged in the MCS protocol, consisting of control information transferred between MCS providers to coordinate thei
47、r joint operation and possibly data transferred on behalf of MCS users to whom they are providing service. 3.4 MCS data transfer priority: One of four levels: top, high, medium, low. The value is communicated unchanged from transmitter to receivers. Depending on an MCS domain parameter for the numbe
48、r of distinct data transfer priorities implemented, two or more lowest priorities may receive the same quality of service. 3.5 valid MCSPDU: An MCSPDU whose structure and encoding complies with this Recommendation. 3.6 3.7 Recommendation. 3.8 Connect-Result. . invalid MCSPDU: An MCSPDU that is not a
49、 valid MCSPDU. protocol error: Use of an MCSPDU in a manner inconsistent with the procedures of this connect MCSPDU: Any one of Connect-Initial, Connect-Response, Connect-Additional, 3.9 extended parameters MCSPDU: Either Extended-Parameter-Propose or Extended- Parameter-Accept. 3.10 domain MCSPDU: Any MCSPDU that is not a connect MCSPDU or an extended parameter MCSPDU. 3.11 data MCSPDU: Any one of SendDataRequest, SendDataIndication, UniformSendDataRequest, UniformSendDataIndication. 3.12 control MCSPDU: Any domain MCSPDU that is not a data MCS
