1、 International Telecommunication Union ITU-T T.123TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (01/2007) SERIES T: TERMINALS FOR TELEMATIC SERVICES Network-specific data protocol stacks for multimedia conferencing ITU-T Recommendation T.123 ITU-T Rec. T.123 (01/2007) i ITU-T Recommendation T.123
2、Network-specific data protocol stacks for multimedia conferencing (revised in 1999) Summary ITU-T Recommendation T.123 specifies network-specific aspects of the T.120-series data protocols for multimedia conferencing. The networks currently identified are ISDN, CSDN, PSDN, PSTN, B-ISDN, and LAN. Com
3、munication profiles are specified which provide reliable point-to-point connections between a terminal and a multipoint control unit, between pairs of terminals or between pairs of MCUs. In some cases, a lower protocol layer allows the multiplexing of audio and video signals in addition to data conn
4、ections. In other cases, separate calls, over the same or a different network, may be established to carry audio or video signals. In addition, Annex B specifies a protocol that may be used to negotiate connection services beyond reliable data transfer. This protocol also provides for the use of ali
5、as address lists when making a connection. Alias lists will allow proxy services for T.120 communications to be created and used. This revised version of ITU-T Recommendation T.123 introduces a number of clarifications to the previous version. Source ITU-T Recommendation T.123 was approved on 13 Jan
6、uary 2007 by ITU-T Study Group 16 (2005-2008) under the ITU-T Recommendation A.8 procedure. ii ITU-T Rec. T.123 (01/2007) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Se
7、ctor (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 eve
8、ry 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-Ts purvie
9、w, 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 volunt
10、ary. 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 n
11、egative 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 th
12、e 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 Recommenda
13、tion, 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
14、:/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. ITU-T Rec. T.123 (01/2007) iii CONTENTS Page 1 Scope 1 1.1 Networks identified 1 1.2 Audio and video signals . 1 1.3 ISDN call
15、set-up . 1 2 References. 1 3 Definitions 5 4 Abbreviations and acronyms 5 5 Multipoint configuration. 6 6 Profile overview . 7 7 Basic profiles 9 7.1 ISDN basic profile 9 7.2 CSDN basic profile. 10 7.3 PSDN basic profile. 11 7.4 PSTN basic profile . 12 7.5 B-ISDN basic profile 13 7.6 LAN basic profi
16、le. 14 8 Packet header to delimit data units in an octet stream 15 9 Synchronization and convergence function 15 9.1 SCF overview . 15 9.2 SCF procedures 17 9.3 SCF messages. 19 9.4 Quality of service parameters. 21 10 Q.922 protocol parameters and options 21 11 Data link frame structure transparenc
17、y for start-stop transmission 22 12 Physical sublayer formed by H.221 MLP channels 23 13 Alternative profiles . 25 13.1 Alternative: ISDN based on ITU-T Q.922. 25 13.2 Alternative: ISDN based on ITU-T T.90. 26 13.3 Alternative: ISDN based on ITU-T V.120. 27 13.4 Alternative: PSTN based on ITU-T H.32
18、4 28 13.5 Alternative: B-ISDN based on ITU-T H.222. 28 13.6 Alternative: LAN based on data unit transfer. 29 Annex A Integration of multimedia signals framed according to ITU-T H.221 31 Annex B Extended transport connections. 32 B.1 Scope 32 B.2 References 32 B.3 Definitions 32 iv ITU-T Rec. T.123 (
19、01/2007) Page B.4 Abbreviations and acronyms 33 B.5 Conventions 33 B.6 Overview 33 B.7 Extended transport connections 35 B.8 Extended profiles 40 B.9 Connection negotiation protocol (CNP). 46 B.10 Unreliable segmentation and reassembly protocol. 55 Appendix I Multimedia conference call set-up in the
20、 ISDN 58 I.1 Introduction 58 I.2 Basic requirements . 58 I.3 Connection phase 61 I.4 Phase A (ISDN D-channel protocol) 62 I.5 Phase B (H.242 protocol) . 62 I.6 Phase C (T.120-series protocol) . 62 Appendix II GSS-API security framework. 63 II.1 Introduction 63 II.2 IETF common authentication technol
21、ogy (CAT). 63 II.3 T.123 Annex B security framework . 63 Bibliography. 65 ITU-T Rec. T.123 (01/2007) 1 ITU-T Recommendation T.123 Network-specific data protocol stacks for multimedia conferencing (revised in 1999) 1 Scope This Recommendation, which defines protocol stacks for terminals and MCUs, spe
22、cifies network-specific aspects of the T.120 protocol suite in the form of profiles for each network identified. Each profile specifies a set of protocols that extend to layer 4 of the OSI reference model. The rationale for this Recommendation is as follows: audiographic and video conferencing are i
23、ntended to form part of the repertoire of ISDN services. Teleconferencing via ISDN involves the integration of multiple media (audio, video and data) in a connection, which may be the aggregate of a number of physical channels. The provision of these services is not, however, limited to the ISDN, an
24、d a range of other network scenarios is identified. For instance, CSDN may provide a similar, though less flexible, service to that of ISDN, and PSTN may provide a service that, though limited in performance, is more readily available. Teleconferencing may also be extended over PSDN and B-ISDN. LANs
25、 may provide conferencing locally within an enterprise or a means of access to wide area networks. 1.1 Networks identified Network-specific profiles are defined for ISDN, CSDN, PSDN and PSTN, as required by ITU-T F.702. The scope of this Recommendation also includes B-ISDN and LAN. 1.2 Audio and vid
26、eo signals The handling of audio and video signals in a multimedia conference is not part of this Recommendation, other than the possibility of their multiplexed transport over the same connection in some cases. 1.3 ISDN call set-up Examples of ISDN call set-up procedures for the audiographic teleco
27、nference are given in Appendix I. These procedures illustrate: a) the use of ISDN information elements; b) coordination of the D-channel and the B-channel; c) the phases of connection establishment; d) interworking with telephone services. 2 References The following ITU-T Recommendations and other r
28、eferences 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
29、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, th
30、e status of a Recommendation. 2 ITU-T Rec. T.123 (01/2007) 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 audiovisual teleservices. ITU-T H.222.0 ITU-T Recommendation H.2
31、22.0 (2006) | ISO/IEC 13818-1:2006, Information technology Generic coding of moving pictures and associated audio information: Systems. ITU-T H.223 ITU-T Recommendation H.223 (2001), Multiplexing protocol for low bit rate multimedia communication. ITU-T H.230 ITU-T Recommendation H.230 (2004), Frame
32、-synchronous control and indication signals for audiovisual systems. ITU-T H.231 ITU-T Recommendation H.231 (1997), Multipoint control units for audiovisual systems using digital channels up to 1920 kbit/s. ITU-T H.233 ITU-T Recommendation H.233 (2002), Confidentiality system for audiovisual service
33、s. ITU-T H.242 ITU-T Recommendation H.242 (2004), System for establishing communication between audiovisual terminals using digital channels up to 2 Mbit/s. ITU-T H.243 ITU-T Recommendation H.243 (2005), Procedures for establishing communication between three or more audiovisual terminals using digi
34、tal channels up to 1920 kbit/s. ITU-T H.310 ITU-T Recommendation H.310 (1998), Broadband audiovisual communication systems and terminals. ITU-T H.320 ITU-T Recommendation H.320 (2004), Narrow-band visual telephone systems and terminal equipment. ITU-T H.324 ITU-T Recommendation H.324 (2005), Termina
35、l for low bit-rate multimedia communication. ITU-T I.320 ITU-T Recommendation I.320 (1993), ISDN protocol reference model. ITU-T I.321 ITU-T CCITT Recommendation I.321 (1991), B-ISDN protocol reference model and its application. ITU-T I.361 ITU-T Recommendation I.361 (1999), B-ISDN ATM layer specifi
36、cation. ITU-T I.363.1 ITU-T Recommendation I.363.1 (1996), B-ISDN ATM Adaptation Layer specification: Type 1 AAL. ITU-T I.363.3 ITU-T Recommendation I.363.3 (1996), B-ISDN ATM Adaptation Layer specification: Types 3/4 AAL. ITU-T I.363.5 ITU-T Recommendation I.363.5 (1996), B-ISDN ATM Adaptation Laye
37、r specification: Type 5 AAL. ITU-T I.365.1 ITU-T Recommendation I.365.1 (1993), B-ISDN ATM adaptation layer sublayers: Frame relaying service specific convergence sublayer (FR-SSCS). ITU-T I.365.3 ITU-T Recommendation I.365.3 (1995), B-ISDN ATM adaptation layer sublayers: Service-specific coordinati
38、on function to provide the connection-oriented transport service. ITU-T I.430 ITU-T Recommendation I.430 (1995), Basic user-network interface Layer 1 specification. ITU-T Rec. T.123 (01/2007) 3 ITU-T I.431 ITU-T Recommendation I.431 (1993), Primary rate user-network interface Layer 1 specification.
39、ITU-T I.432.1 ITU-T Recommendation I.432.1 (1999), B-ISDN user-network interface Physical layer specification: General characteristics. ITU-T I.432.2 ITU-T Recommendation I.432.2 (1999), B-ISDN user-network interface Physical layer specification: 155 520 kbit/s and 622 080 kbit/s operation. ITU-T I.
40、432.3 ITU-T Recommendation I.432.3 (1999), B-ISDN user-network interface Physical layer specification: 1544 kbit/s and 2048 kbit/s operation. ITU-T I.432.4 ITU-T Recommendation I.432.4 (1999), B-ISDN user-network interface Physical layer specification: 51 840 kbit/s operation. ITU-T Q.920 ITU-T Reco
41、mmendation Q.920 (1993), ISDN user-network interface data link layer General aspects. ITU-T Q.921 ITU-T Recommendation Q.921 (1997), ISDN user-network interface Data link layer specification. ITU-T Q.921 bis ITU-T Recommendation Q.921 bis (1993), Abstract test suite for LAPD conformance testing. ITU
42、-T Q.922 ITU-T CCITT Recommendation Q.922 (1992), ISDN data link layerspecification for frame mode bearer services. ITU-T Q.931 ITU-T Recommendation Q.931 (1998), ISDN user-network interface layer 3 specification for basic call control. ITU-T Q.933 ITU-T Recommendation Q.933 (2003), ISDN Digital Sub
43、scriber Signalling System No. 1 (DSS1) Signalling specifications for frame mode switched and permanent virtual connection control and status monitoring. ITU-T Q.2110 ITU-T Recommendation Q.2110 (1994), B-ISDN ATM adaptation layer Service specific connection oriented protocol (SSCOP). ITU-T Q.2130 IT
44、U-T Recommendation Q.2130 (1994), B-ISDN signalling ATM adaptation layer Service specific coordination function for support of signalling at the user-network interface (SSFC at UNI). ITU-T Q.2931 ITU-T Recommendation Q.2931 (1995), Digital Subscriber Signalling System No. 2 User-Network interface (U
45、NI) layer 3 specification for basic call/connection control. ITU-T T.90 ITU-T CCITT Recommendation T.90 (1992), Characteristics and protocols for terminals for telematic services in ISDN. ITU-T T.120 ITU-T Recommendation T.120 (2007), Data protocols for multimedia conferencing. ITU-T T.122 ITU-T Rec
46、ommendation T.122 (1998), Multipoint communication service Service definition. ITU-T T.124 ITU-T Recommendation T.124 (2007), Generic Conference Control. ITU-T T.125 ITU-T Recommendation T.125 (1998), Multipoint communication service protocol specification. ITU-T T.126 ITU-T Recommendation T.126 (19
47、97), Multipoint still image and annotation protocol. ITU-T T.127 ITU-T Recommendation T.127 (1995), Multipoint binary file transfer protocol. 4 ITU-T Rec. T.123 (01/2007) ITU-T V.7 ITU-T CCITT Recommendation V.7 (1988), Definitions of terms concerning data communication over the telephone network. I
48、TU-T V.8 ITU-T Recommendation V.8 (2000), Procedures for starting sessions of data transmission over the public switched telephone network. ITU-T V.8 bis ITU-T Recommendation V.8 bis (2000), Procedures for the identification and selection of common modes of operation between data circuit-terminating
49、 equipments (DCEs) and between data terminal equipments (DTEs) over the public switched telephone network and on leased point-to-point telephone-type circuits. ITU-T V.14 ITU-T Recommendation V.14 (1993), Transmission of start-stop characters over synchronous bearer channels. ITU-T V.34 ITU-T Recommendation V.34 (1998), A modem operating at data signalling rates of up to 33 600 bit/s for use on the general switched telephone netwo
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