1、 International Telecommunication Union ITU-T T.124TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (01/2007) SERIES T: TERMINALS FOR TELEMATIC SERVICES Generic Conference Control ITU-T Recommendation T.124 ITU-T Rec. T.124 (01/2007) i ITU-T Recommendation T.124 Generic Conference Control Summary ITU-
2、T Recommendation T.124 provides a high-level framework for conference management and control of multimedia terminals and Multipoint Control Units (MCUs). It encompasses Generic Conference Control (GCC) functions such as conference establishment and termination, managing the roster of terminals parti
3、cipating in a conference, managing the roster of applications and application capabilities within a conference, registry services for use by applications, coordination of conference conductorship, as well as other miscellaneous functions. It depends on companion Recommendations T.122 and T.125 (MCS)
4、 and T.123 as part of the T.120 infrastructure. This revised version of T.124 introduces a number of clarifications to the previous version. Source ITU-T Recommendation T.124 was approved on 13 January 2007 by ITU-T Study Group 16 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Re
5、c. T.124 (01/2007) 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 ta
6、riff 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 Recom
7、mendations 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 standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recomme
8、ndation, 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. interoperabil
9、ity 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 compl
10、iance 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
11、 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
12、 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,
13、by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. T.124 (01/2007) iii CONTENTS Page 1 Scope 1 2 References 2 3 Definitions 3 4 Abbreviations . 7 5 Conventions 7 6 Overview 8 6.1 System model for a conference node . 9 6.2 Conference establishment and termination 10 6.3
14、The conference roster. 11 6.4 The application roster. 11 6.5 The Application Registry . 11 6.6 Conference conductorship 11 6.7 Miscellaneous functions. 12 6.8 Scalable conferences 12 6.9 Summary of GCC abstract services . 13 7 GCC service definition. 17 7.1 Conference establishment and termination 1
15、7 7.2 The conference roster. 54 7.3 The application roster. 60 7.4 The Application Registry . 74 7.5 Conference conductorship 84 7.6 Miscellaneous functions. 93 8 GCC Protocol Specification . 98 8.1 General operation . 98 8.2 Conference establishment and termination 99 8.3 The conference and applica
16、tion rosters 127 8.4 The Application Registry . 150 8.5 Conference conductorship 159 8.6 Miscellaneous functions. 165 8.7 GCCPDU definitions 167 9 Use of the Multipoint Communication Service 189 9.1 MCS services 189 9.2 Channel allocation 190 9.3 Token allocation. 191 9.4 Use of MCS data transmissio
17、n services . 191 9.5 Encoding of PDUs in MCS primitives. 193 9.6 Format of User Data parameter of MCS-Connect-Provider 194 9.7 Interpretation of the MCS Domain Selector 194 iv ITU-T Rec. T.124 (01/2007) Page Annex A Static channel and token ID assignments 196 A.1 Static channel ID assignments 196 A.
18、2 Static token ID assignments . 196 Annex B Object Identifier assignments 197 Annex C Network Address Parameter Description and use 198 Appendix I Relationship of T.120 to H.243 in H.320 conferences 199 I.1 Introduction 199 I.2 Conference selection and Password protection 199 I.3 Alternative Node ID
19、. 200 ITU-T Rec. T.124 (01/2007) 1 ITU-T Recommendation T.124 Generic Conference Control 1 Scope This Recommendation provides a high-level framework for conference management and control of audiographic and audiovisual terminals and Multipoint Control Units (MCUs). It encompasses Generic Conference
20、Control (GCC) functions such as conference establishment and termination, managing the roster of nodes participating in a conference, managing the roster of Application Protocol Entities and Application Capabilities within a conference, registry services for use by Application Protocol Entities, coo
21、rdination of conference conductorship, as well as other miscellaneous functions. This Recommendation is defined within the framework of ITU-T T.120. Included within this framework are companion ITU-T T.122 and ITU-T T.125, which define the multipoint delivery mechanism used in this Recommendation, a
22、nd ITU-T T.123, which specifies the Audiovisual Protocol Stacks for each of the communication networks supported. Figure 1-1 presents an overview of the scope of this Recommendation and its relationship to the other elements of the T.120 framework within a single node. 2 ITU-T Rec. T.124 (01/2007) F
23、igure 1-1 Scope of T.124 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 referenc
24、es 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
25、a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T F.702 ITU-T Recommendation F.702 (1996), Multimedia conference services. ITU-T H.221 ITU-T Recommendation H.221 (2004), Frame structure for a 64 to 1920 kbit/s channel in audiovis
26、ual teleservices. ITU-T T.35 ITU-T Recommendation T.35 (2000), Procedure for the allocation of ITU-T defined codes for non-standard facilities. ITU-T T.120 ITU-T Recommendation T.120 (2007), Data protocols for multimedia conferencing. ITU-T Rec. T.124 (01/2007) 3 ITU-T T.122 ITU-T Recommendation T.1
27、22 (1998), Multipoint communication service Service definition. ITU-T T.123 ITU-T Recommendation T.123 (2007), Network-specific data protocol stacks for multimedia conferencing. ITU-T T.125 ITU-T Recommendation T.125 (1998), Multipoint communication service protocol specification. ITU-T T.126 ITU-T
28、Recommendation T.126 (1997), Multipoint still image and annotation protocol. ITU-T T.127 ITU-T Recommendation T.127 (1995), Multipoint binary file transfer protocol. ITU-T X.680 ITU-T Recommendation X.680 (2002) | ISO/IEC 8824-1:2002, Information technology Abstract Syntax Notation One (ASN.1): Spec
29、ification of basic notation. ITU-T X.691 ITU-T Recommendation X.691 (2002) | ISO/IEC 8825-2:2002, Information technology ASN.1 encoding rules: Specification of Packed Encoding Rules (PER). ISO/IEC 10646 ISO/IEC 10646:2003, Information technology Universal Multiple-Octet Coded Character Set (UCS). 3
30、Definitions This Recommendation defines the following terms: 3.1 anonymous node: This node category describes a T.120 node that can participate in a conference while not being visible to any other nodes in the conference. The presence of Anonymous nodes is needed to facilitate large-scale T.120 conf
31、erences. 3.2 application protocol: Any standard or non-standard protocol specification which is designed to make use of T.120 services. 3.3 application protocol entity: The instantiation of an Application Protocol in a terminal or MCU. Application Protocol Entities are employed by User Applications,
32、 but are not themselves User Applications. An Application Protocol Entity communicates with GCC through the GCC Provider present at its local terminal or MCU via a GCCSAP. Only Application Protocol Entities communicate with GCC Providers; User Applications do not. Multiple Application Protocol Entit
33、ies based on the same Application Protocol may enroll at a single node. These may be either in the same or separate Application Protocol Sessions. A single Application Protocol Entity is assumed to communicate with the local GCC Provider via a single GCCSAP, and is also assumed to have a single MCS
34、User ID if it has enrolled in the active state. An Application Protocol Entity which has enrolled in the active state is part of a single Application Protocol Session as indicated by its Session ID (or lack of a Session ID which indicates that it is part of the Default Session). An Application Proto
35、col Entity which has enrolled in the inactive state is not considered part of any Application Protocol Session; however, an inactive Application Protocol Entity may make use of GCC services and information associated with such an Application Protocol Entity is included in the Application Roster. 3.4
36、 application protocol key: The Application Protocol Key identifies the type of Application Protocol for an Application Protocol Session. Multiple Application Protocol Sessions of the same type would be identified using the same Application Protocol Key (but different Session IDs). An Application Pro
37、tocol Key is either an ASN.1 OBJECT IDENTIFIER belonging to a Recommendation, Standard, or non-standard protocol, or, alternatively, it is a non-standard identifier using the encoding conventions of ITU-T H.221. 4 ITU-T Rec. T.124 (01/2007) 3.5 application protocol session: A set of Peer Application
38、 Protocol Entities. 3.6 application record: A set of information for a specific Application Protocol Entity at a specific node. This set includes the Application User ID, the Active/Inactive flag, as well as other parameters. 3.7 application registry: A central repository located at the Top GCC Prov
39、ider where an Application Protocol Entity can register its use of tokens, channels, and other parameters. Peer Application Protocol Entities can then access the registry to discover this registered information. 3.8 application roster: The set of all Application Records from all enrolled Application
40、Protocol Entities at all nodes in a conference, including the Application Capabilities List for each Application Protocol Session. 3.9 application user ID: MCS User ID assigned by MCS to an Application Protocol Entity. 3.10 conducted mode: Conducted Mode allows a Conductor node the ability to contro
41、l Application Protocol Entities at all nodes in a conference, and to restrict operation of Application Protocol Entities by other nodes. Conducted mode is established when a Conductor has been assigned to a conference. This is achieved when a node has successfully grabbed the conference Conductor To
42、ken. 3.11 conductor: The Conductor, if present, is a node in a conference which controls certain aspects of the conference (e.g., control of communication between Application Protocol Entities, control over conference participants, and conference termination). There shall be either zero or one Condu
43、ctors in a conference. A node becomes conductor by grabbing the conductor token, or by requesting or accepting conductorship from the current conductor. 3.12 conference: A number of nodes that are joined together and that are capable of exchanging audiographic and audiovisual information across vari
44、ous communication networks. 3.13 conference application roster: A database maintained by each GCC Provider consisting of a set of Application Records, one for every Application Protocol Entity at every node in the conference, as well as other information such as the Application Capabilities List for
45、 each Application Protocol Session. 3.14 conference mode: When a conference is created, a Conference Mode is specified, by the Convener, that defines which Categories of nodes will be allowed to participate in the conference. These Conference Modes include the following: conventional-only, which all
46、ows only Conventional nodes to join the conference; counted-controlled, which allows only Counted and Conventional nodes to join the conference; anonymous-controlled, which allows only Anonymous and Conventional nodes to join the conference; and unrestricted-mode, which allows all three node categor
47、ies to participate in the conference. The Node Controller must use the T.124 password to determine which nodes may join as Conventional when the Conference Mode is either counted-controlled or anonymous-controlled. 3.15 conference profile: A database maintained by each GCC Provider consisting of inf
48、ormation pertinent to a conference as a whole such as Conference Name, Password (if any), etc. 3.16 conference roster: A database maintained by each GCC Provider consisting of a list of nodes in a conference. For each node, this list includes the Node ID of the node, type of the node, the name of th
49、e node, and may include a list of participants at the node, as well as other optional information. 3.17 control GCC service access point: The communication interface between a GCC Provider and the Node Controller within a single node. 3.18 convener: Node that created a conference by issuing the GCC-Conference-Create request primitive. ITU-T Rec. T.124 (01/2007) 5 3.19 convener password: An identifying numeric string, as well as optional text string, which may be used when a conference is created to allow the convener of the co
