1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU H.248 (06/2000) SERIES H: AUDIOVISUAL AND MULTIMEDIA SYSTEMS Infrastructure of audiovisual services - Communication procedures Gateway control protocol ITU-T Recommendation H248 (Formerly CCITT Recommendation
2、) Characteristics of transmission channels used for other than telephone purposes Use of telephone-type circuits for voice-frequency telegraphy Telephone circuits or cables used for various types of telegraph transmission or simultaneous transmission Telephone-type circuits used for facsimile telegr
3、aphy Characteristics of data signals CHARACTERISTICS OF VISUAL TELEPHONE SYSTEMS INFRASTRUCTURE OF AUDIOVISUAL SERVICES General Transmission multiplexing and synchronization Systems aspects Communication procedures Coding of moving video Related systems aspects Systems and terminal equipment for aud
4、iovisual services Supplementary services for multimedia H.10-H.19 H.20-H.29 H.30-H.39 H.40-H.49 H.50-H.99 H.100-H.199 H.200-H.219 H.220-H.229 H.230-H.239 H.240-H.259 H.260-H279 H.280-H.299 H.300-H.399 H .450-H.499 For further details, please refer to ITU-TList of Recommendations GATEWAY CONTROL PROT
5、OCOL Summary To achieve greater scalability, this Recommendation decomposes the H.323 Gateway function defined in Recommendation H.246 into functional subcomponents and specifies the protocols these components use to communicate. This allows implementations of H.323 gateways to be highly scalable an
6、d encourages leverage of widely deployed SCN network capabilities such as SS7 switches. This also enables H.323 gateways to be composed of components from multiple vendors distributed across multiple physical platforms. The purpose of this Recommendation is to add capabilities currently defined for
7、H.323 systems and is intended to provide new ways of performing operations already supported in H.323. Source ITU-T Recommendation H.248 was prepared by ITU-T Study Group 16 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on 15 June 2000. FORE WORD ITU (International Telecommu
8、nication 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-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them w
9、ith a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of
10、Recommendations by the Members of the ITU-T is covered by the procedurelaid down in WTSC Resolution No. l. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation, the expres
11、sion “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Int
12、ellectual 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 outside of the Recommendation development process. As of the date of approval of this Recommendation, the ITU had
13、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 the latest information and are therefore strongly urged to consult the TSB patent database. / ITU 2001 All rights re
14、served. 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 writing from the ITU. 1 2 2.1 2.2 3 4 5 6 6.1 6.2 7 7.1 Scope References Normative references Informative references De
15、finitions Abbreviations . Conventions Connection model . Contexts 6.1.1 Context attributes and descriptors . 6.1.2 Creating, deleting and modifying Contexts . Terminations . 6.2.1 Termination dynamics . 6.2.2 TerminationIDs . 6.2.3 Packages 6.2.4 Termination properties and descriptors . 6.2.5 Root T
16、ermination Commands Descriptors 7.1.1 7.1.2 7.1.3 7.1.4 7.1.5 7.1.6 7.1.7 7.1.8 7.1.9 7.1.10 7.1.1 1 7.1.12 7.1.13 7.1.14 7.1.15 7.1.16 7.1.17 Specifying parameters . Modem descriptor . Multiplex descriptor Media descriptor Terminationstate descriptor Stream descriptor . LocalControl descriptor . Lo
17、cal and Remote descriptors . Events descriptor . EventBuffer descriptor Signals descriptor Audit descriptor . Servicechange descriptor DigitMap descriptor Statistics descriptor . Packages descriptor . ObservedEvents descriptor Page 1 1 1 3 3 4 5 5 6 7 7 7 8 8 8 9 10 10 11 11 12 12 12 12 13 13 14 16
18、17 18 19 19 20 23 23 23 7.2 7.3 8 8.1 8.2 8.3 9 9.1 9.2 10 10.1 10.2 10.3 11 11.1 11.2 11.3 11.4 11.5 12 STD-ITU-T RECMN H-248-ENGL 2000 m 48b257L Ob83471 07b m Page 7 . 1 . 18 Topology descriptor 23 Command Application Programming Interface . 7.2.1 Add 7.2.2 Modify . 7.2.3 Subtract 7.2.4 Move 7.2.5
19、 Auditvalue 7.2.6 Auditcapabilities . 7.2.7 Notify . 7.2.8 Servicechange . 7.2.9 Manipulating and Auditing Context Attributes . 7.2.1 O Generic Command Syntax Command Error Codes . Transactions Common parameters . 8 . 1 . 1 Transaction Identifiers . 8.1.2 Context Identifiers . : . Transaction Applic
20、ation Programming Interface . 8.2.1 TransactionRequest . 8.2.3 TransactionPending . 8.2.2 TransactionReply . 25 25 26 27 28 29 30 31 31 34 34 35 36 37 37 38 38 38 38 39 Messages . 39 Transport . 40 Ordering of Commands 40 Protection against Restart Avalanche . 41 Security considerations . 42 Protect
21、ion of Protocol Connections 42 Interim AH scheme . 42 Protection of Media Connections . 43 MG-MGC Control Interface . 43 Multiple Virtual MGs . 43 Cold start 44 Negotiation of protocol version 44 Failure of a MG 45 Failure of an MGC 45 Package definition 46 12.1 12.2 12.3 12.4 12.5 13 13.1 13.2 13.3
22、 Guidelines for defining packages . 12.1.1 Package 12.1.2 Properties . 12.1.3 Events 12.1.4 Signals . 12.1 . 5 Statistics 12.1.6 Procedures . Guidelines to defining Properties, Statistics and Parameters to Events and Signals Lists Identifiers Package registration IANA considerations Packages . Error
23、 codes ServiceChange reasons . Annex A Binary encoding ofthe protocol A . 1 Coding of wildcards . A.2 ASN.l syntax specification A.3 Dlgt maps and path names . Annex B Text encoding ofthe protocol . B . 1 Coding of wildcards . B.2 ABNF specification c . 1 c.2 (2.3 c.4 CS C.6 c.7 C.8 c.9 c.10 c.11 c.
24、12 Annex C Tags for media stream properties General media attributes . Mux properties General bearer properties General ATM properties . Frame Relay IP . ATM AAL2 ATM AAL1 Bearer capabilities AAL5 properties . SDP equivalents H.245 Page 46 46 47 47 48 48 48 48 49 49 49 49 49 49 50 50 50 51 64 65 65
25、65 75 75 76 76 76 78 79 79 80 81 89 89 90 Annex D Transport over IP D . 1 Transport over IP/UDP using Application Level Framing . D.l . 1 Providing At-Most-Once fimctionality . D . 1.2 Transaction identifiers and three-way handshake . D . 1.3 Computing retransmsslon timers D . 1.4 Provisional respon
26、ses D . 1.5 Repeating Requests, Responses and Acknowledgements . D.2 Using TCP D.2.1 Providing the At-Most-Once functionality D.2.2 Transaction identifiers and three-way handshake . D.2.3 Computing retransrnlsslon timers D.2.4 Provisional responses D.2.5 Ordering of commands Annex E Basic packages .
27、 E . 1 E.2 E.3 E.4 ES Generic E.l.l Properties . E . 1.2 Events E . 1.3 Signals . E.1.4 Statistics Base Root Package . E.2.1 Properties . E.2.2 Events E.2.3 Signals . E.2.4 Statistics E.2.5 Procedures . Tone Generator Package . E.3.1 Properties . E.3.2 Events E.3.3 Signals . E.3.4 Statistics E.3.5 P
28、rocedures . Tone Detection Package . E.4.1 Properties . E.4.2 Events E.4.3 Signals . E.4.4 Statistics E.4.5 Procedures . Basic DTMF Generator Package Page 90 90 90 91 91 92 92 93 93 94 94 94 94 94 94 94 95 96 96 96 96 97 97 97 97 97 98 98 98 98 98 98 99 99 1 00 1 00 1 00 1 00 E.6 E.5.1 Properties .
29、E.5.2 Events E.5.3 Signals . E.5.4 Statistics E . 5.5 Procedures . DTMF detection Package . E.6.1 Properties . E.6.2 Events E.6.3 Signals . E.6.4 Statistics E.6.5 Procedures . E.7 Call Progress Tones Generator Package . E.7.1 Properties . E.7.2 Events E.7.3 Signals . E.7.4 Statistics E.7.5 Procedure
30、s . E.8 Call Progress Tones Detection Package . E.8.1 Properties . E.8.2 Events E.8.3 Signals . E.8.4 Statistics E.8.5 Procedures . E.9 Analog Line Supervision Package E.9.1 Properties . E.9.2 Events E.9.3 Signals . E.9.4 Statistics E.9.5 Procedures . E.9.6 Error code E.10 Basic Continuity Package .
31、 E . 1 O . 1 Properties . E . 10.3 Signals . E . 10.4 Statistics E . 10.5 Procedures . E.ll Network Package E.11.1 Properties . E.11.2 Events E . 10.2 Events Page 101 101 101 101 102 102 102 102 103 103 103 103 103 103 104 104 104 104 105 105 105 105 105 105 105 105 107 107 107 107 108 108 108 108 1
32、08 109 109 109 109 STD-ITU-T RECMN H-248-ENGL 2000 48b257L Ob83495 731 E . 1 1.3 Signals . E . 11.4 Statistics E.l 1.5 Procedures . E . 12 RTP Package E.12.1 Properties . E . 12.2 Events E . 12.3 Signals . E.12.4 Statistics E.12.5 Procedures . E . 13 TDM Circuit Package . E.13.1 Properties . E . 13.
33、2 Events E . 13.3 Signals . E . 13.4 Statistics E.13.5 Procedures . Appendix I Example Call Flows 1.1 Residential Gateway to Residential Gateway Call . I . 1.1 Programming Residential GW Analog Line Terminations for Idle Behaviour T . 1.2 Collecting Originator Digits and Initiating Termination . Pag
34、e 110 110 111 111 111 111 111 111 112 112 112 113 113 113 113 113 113 114 115 Recommendation H.248 GATEWAY CONTROL PROTOCOL (Geneva, 2000) 1 Scope Recommendation H.248 defines the protocols used between elements of a physically decomposed multimedia gateway, used in accordance with the architecture
35、as specified in Recommendation H.323. There are no hctional differences from a system view between a decomposed gateway, with distributed sub-components potentially on more than one physical device, and a monolithic gateway such as described in Recommendation H.246. This Recommendation does not defi
36、ne how gateways, multipoint control units or interactive voice response units (IVRs) work. Instead it creates a general framework that is suitable for these applications. Packet network interfaces may include P, ATM or possibly others. The interfaces will support a variety of SCN signalling systems,
37、 including tone signalling, ISDN, ISUP, QSIG and GSM. National variants of these signalling systems will be supported where applicable. 2 References The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recomm
38、endation. 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 encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other ref
39、erences listed below. A list of the currently valid ITU-T Recommendations is regularly published. 2.1 Normative references ITU-T Recommendation H.225.0 (1999), Call signalling protocols and media stream packetization for packet-based multimedia communication systems. ITU-T Recommendation H.235 (1998
40、), Security and encryption for H-Series (H.323 and other H.245-based) multimedia terminals. ITU-T Recommendation H.245 (1998), Control protocol for multimedia communication. ITU-T Recommendation H.246 (1998), Interworking of H-series multimedia terminais with H-series multimedia terminals and voiceh
41、oiceband terminals on GSnV and ISDN. ITU-T Recommendation H.323 (1999), Packet-based multimedia communication systems. ITU-T Recommendation 1.363.1 (1 996), B-ISDN ATM adaptation layer (AAL) speciJication: Type I AAL. ITU-T Recommendation 1.363.2 (1997), B-ISDN ATM adaptation iayer (AAL) specflcatio
42、n: Type 2 AAL. ITU-T Recommendation 1.363.5 (1996), B-ISDN ATM adaptation layer (AAL) specification: Type 5 AAL. ITU-T Recommendation 1.366.1 (1998), Segmentation and Reassembly Service Speczjc Convergence Sublayer for the AAL type 2. ITU-T Recommendation 1.366.2 (1 999), AAL type 2 service speczfic
43、 convergence sublayer for trunking. ITU-T Recommendation 1.371 (2000), Traf$c control and congestion control in B-ISDN. ITU-T Recommendation Q.763 (1999), Signalling System No. 7 ISDN user part formats and codes. ITU-T Recommendation Q.765 (2000), Signalling System No. 7 - Application transport mech
44、anism. ITU-T Recommendation Q.93 1 (1 998), ISDN user-network interface layer 3 speczjcation for basic call control. ITU-T Recommendation 4.2630.1 (1999), AAL type 2 signalling protocol (Capability Set 1). ITU-T Recommendation Q.293 1 (1 995), Digital Subscriber Signalling System No. 2 (DSS2) User-N
45、etwork Interface (UNI,) Layer 3 specljcation for basic caWconnection control. ITU-T Recommendation Q.2941.1 (1997), Digital Subscriber Signalling Sstem No. 2 Generic identifier transport. ITU-T Recommendation Q.296 1.1 (1 999, Additional signalling capabilities to support traffic parameters for the
46、tagging option and the sustainable call note parameter set. ITU-T Recommendation 4.2961.2 (1 997), Additional trafjc parameters: Support of ATM transfer capability in the broadband bearer capability information element. ITU-T Recommendation Q.2965.1 (1 999), Digital subscriber signalling system No.
47、2 - Support of Quality of Service classes. ITU-T Recommendation Q.2965.2 (1999), Digital subscriber signalling system No. 2 - Signalling of individual Quality of Service parameters. ITU-T Recommendation V.76 (1 996), Generic multiplexer using V.42 LAPM-based procedures. ITU-T Recommendation X.2 13 (
48、1 995), Information technology Open Systems Interconnection Network service definition plus Amendment 1 (1997) Addition of the Internet protocol address format identzjer. ITU-T Recommendation X.680 (1 997), Information technology Abstract Syntax Notation One (ASN.): Speczjcation of basic notation. A
49、TM Forum (1996), ATM User-Network Interface (UNI,) Signalling Speczfication Version 4. O. WC 1006, IS0 Transport Service on top of the TCP, Version 3. WC 2234, Augmented BNF for Syntax Speclfications: ABNF. WC 2327, SDP: Session Description Protocol. WC 2402, IP Authentication Heuder. WC 2406, IP Encapsulating Security Payload (ESP). STD.ITlJ-T RECflN H-ZIIB-ENGL ZOOU W VBb2591 ob831178 440 m 2.2 Informative references ITU-T Recommendation E.18O/Q.35 (1998), Technical characteristics of tones for the telephone service. CCITT Recommendation G.711 (1988), Pulse Code Modulati
