1、ECMA Technical Report TR/73December 1998Standardizing Information and Communication SystemsPhone: +41 22 849.60.00 - Fax: +41 22 849.60.01 - URL: http:/www.ecma.ch - Internet: helpdeskecma.chH.323 / B-ISDN SignallingInteroperability.ECMA Technical Report TR/73December 1998Standardizing Information a
2、nd Communication SystemsPhone: +41 22 849.60.00 - Fax: +41 22 849.60.01 - URL: http:/www.ecma.ch - Internet: helpdeskecma.chCW T073.DOC 05-01-99 17,12H.323 / B-ISDN SignallingInteroperability.Brief HistoryThis Technical Report provides information relating to Broadband Integrated Services Digital Ne
3、tworks (includingBroadband Private Integrated Services Networks) and the ways in which they can interoperate with IP-based packetnetworks employing ITU-T recommendation H.323 in support of multimedia communications.The Technical Report is based upon the practical experience of ECMA member companies
4、and the results of theiractive and continuous participation in the work of ISO, ITU-T, ETSI and other international and nationalstandardization bodies. It represents a pragmatic and widely based consensus.This Technical Report was written in cooperation with ETSI and is also published as an ETSI Gui
5、de.This ECMA Technical Report has been adopted by the ECMA General Assembly of December 1998.- i -Table of contents1Scope 12 References 13 Acronyms 24 Introduction 34.1 Overview of H.323 and related recommendations 34.1.1 H.323 concept and entities 34.1.2 Channels defined in H.323 44.1.3 Protocols a
6、nd related standards 44.1.4 Call procedures 54.1.5 Fast connect 64.1.6 Inter-domain signalling 64.2 Overview of modelling work relating to B-ISDN signalling 64.3 Overview of B-ISDN signalling - combined call/bearer control 84.4 Overview of B-ISDN signalling - separated call and bearer control 85 Rel
7、ated work 95.1 ECMA TC32-TG15 and ETSI SPS5 WG5 95.2 ITU-T Study Group 16 95.3 ETSI project TIPHON 105.3.1 General 105.3.2 Gateway functional decomposition 125.4 ATM Forum SAA/RMOA 125.5 ECMA TC32-TG13 125.6 IETF 135.6.1 SIP 135.6.2 IPTEL 135.6.3 E.164 Birds of a Feather activity 135.6.4 NAVDEC 136
8、H.323 and modelling of B-ISDN signalling 137 H.323 interworking via a gateway with B-ISDN separated call and bearer control 137.1 Scenarios 147.2 Protocol interworking architecture 167.2.1 Scenario 1 167.2.2 Scenario 2 187.2.3 Scenario 3 207.3 Session control in B-ISDN environment 207.4 Resource con
9、trol in B-ISDN environment 217.5 Call establishment 217.6 Bearer establishment 217.7 Addressing 22- ii -7.7.1 Addressing in H.323 227.7.2 Addressing in B-ISDN and B-PISN 237.7.3 Address interworking between H.323 and B-ISDN 247.8 Message sequences for basic communication establishment 247.8.1 Scenar
10、ios 1a and 1b 247.8.2 Scenario 1c 267.8.3 Scenarios 2a and 2b 277.8.4 Scenario 2c 297.8.5 Scenario 3c 317.9 Generic Functional Protocol 327.10 Supplementary services 327.10.1 Introduction 327.10.2 Supplementary services in scenario 1 337.10.3 Supplementary services in scenario 2 337.10.4 Supplementa
11、ry services in scenario 3 337.10.5 Areas for further work 347.11 Conferencing 347.12 Impact of T.120 348 H.323 interworking via a gateway with B-ISDN combined call/bearer control 348.1 Scenarios 348.2 Protocol interworking architecture 368.2.1 Scenario 1 368.2.2 Scenario 2 378.2.3 Scenario 3 388.3 S
12、ession control in B-ISDN environment 398.4 Resource control in B-ISDN environment 398.5 Call/bearer establishment 398.6 Addressing 398.7 Message sequences for basic communication establishment 398.7.1 Scenarios 1a and 1b 408.7.2 Scenario 1c 428.7.3 Scenarios 2a and 2b 428.7.4 Scenario 2c 448.7.5 Sce
13、nario 3c 458.8 Generic functional protocol 458.9 Supplementary services 468.10 Conferencing 468.11 Impact of T.120 469 Summary of interworking scenarios in 7 and 8 469.1 Scenario 1 469.2 Scenario 2 469.3 Scenario 3 4710 Application of B-ISDN separated protocols to gatekeeper-to-gatekeeper communicat
14、ion 47- iii -11 Connection of remote H.323 environments via B-ISDN 4711.1 Case 1 full interworking 4711.2 Case 2 - tunnelling 4711.2.1 Scenario T1 - tunnelling of session and resource control protocols 4811.2.2 Scenario T2 - tunnelling of session control protocol only 4911.2.3 Scenario T3 - tunnelli
15、ng of resource control protocol only 4911.2.4 Additional considerations when endstations employ H.323 annex C (native IP network orIP over ATM network) 5011.2.5 Conclusions on tunnelling scenarios 5012 Co-existence of H.323 annex C and B-ISDN signalling in the same network 5113 Impact of H.323 on fu
16、ture mobility protocols 5113.1 Introduction 5113.2 Mobility concepts 5113.3 Mobility architecture 5213.4 Virtual Home Environment (VHE) 5314 Conclusions and recommendations 54- iv -.1ScopeThe purpose of this Technical Report is to investigate the interoperability of H.323 and B-ISDN signallingenviro
17、nments with a view to identifying possible standardization activities in this area. The following aspectsof interoperability are investigated:G01 the interworking of H.323 and B-ISDN environments, both separated and combined, via a gateway;G01 the connection of remote H.323 environments via B-ISDN;G
18、01 the use of H.323 annex C (H.323 on ATM), including the co-existence of H.323 annex C and B-ISDNsignalling in the same network and possible future enhancement of annex C;G01 the application of the B-ISDN separated call control protocol to gatekeeper-to-gatekeepercommunication;G01 the impact of H.3
19、23 on future mobility protocols.For each of the above, due consideration is given to the following: addressing impact (including use of IPaddressing); conferencing models; T.120 data impact; basic call procedures; generic functional procedures(GFP) and supplementary services; end-to-end resource and
20、 session level protocols.Possible future standardization activities resulting from this Technical Report will include H.323 work itemsas well as B-ISDN signalling work items.2 ReferencesECMA-155 Private Integrated Services Networks - Addressing (1997)ECMA-254 Broadband Private Integrated Services Ne
21、twork (B-PISN) - Inter-ExchangeSignalling Protocol - Generic Functional Protocol (1996)ISO/IEC 11571 Information technology - Telecommunications and information exchangebetween systems - Numbering and sub-addressing in private integratedservices networks (1994)ISO/IEC 13247 Information technology -
22、Telecommunications and information exchangebetween systems - Broadband Private Integrated Services Network -Inter-exchange signalling protocol - Basic call/connection control (1997)ATM Forum PNNI 1.0 Private Network-Network Interface Specification Version 1.0 (af-pnni-0055.000) (1996)ATM Forum UNI 4
23、.0 User-Network Interface (UNI) Signalling Specification Version 4.0(af-sig-0061.000) (1996)ETSI DTR/TIPHON-04002 V1.1.6 Telecommunications and Internet Protocol Harmonization Over Networks(TIPHON); Naming and Addressing; Scenario 2 (1998-08)ETSI DTR/TIPHON-00001 V1.1.2 Telecommunications and Intern
24、et Protocol Harmonization Over Networks(TIPHON); Description of technical issues (1998-10)ETSI DTS/TIPHON-02002 V0.2.0 Telecommunications and Internet Protocol Harmonization Over Networks(TIPHON); Network architecture and reference configurations; Phase II:Scenario 1 + Scenario 2 (1998-09)ETSI TS 10
25、1 324 V1.1.6DTR/TIPHON 04001 Telecommunications and Internet Protocol Harmonization Over Networks(TIPHON); Naming and addressing; Scenario 1 (1998-06)IETF RFC 1483 Multiprotocol Encapsulation over ATM Adaptation Layer 5 (1993)- 2 -IETF RFC 1577 Classical IP and ARP over ATM (1994)ITU-T Rec. H.225.0
26、Call signalling protocols and media stream packetization for packet basedmultimedia communication systems (1998)ITU-T Rec. H.245 Control protocol for multimedia communication (1998)ITU-T Rec. H.323 Packet based multimedia communication systems (1998)ITU-T Rec. H.450.1 Generic functional protocol for
27、 the support of supplementary services inH.323 (1998)ITU-T Rec. H.450.2 Call transfer supplementary service for H.323 (1998)ITU-T Rec. H.450.3 Call diversion supplementary service for H.323 (1998)ITU-T Rec. Q.2726.1 B-ISDN user part - ATM end system address (1996)ITU-T Rec. Q.2931 Broadband Integrat
28、ed Services Digital Network (B-ISDN) - DigitalSubscriber Signalling System No. 2 (DSS2) - User-Network Interface(UNI) Layer 3 specification for basic call/connection control (1995)ITU-T Rec. Q.2932.1 Digital Subscriber Signalling System No. 2 - Generic functional protocol:Core functions (1996)ITU-T
29、Rec. Q.931 Digital Subscriber Signalling System No. 1 (DSS 1) - ISDN user-networkinterface layer 3 specification for basic call control (1998)ITU-T Rec. T.120 Data protocols for multimedia conferencing (1996)Draft ITU-T Rec. Q.298x-sbc Broadband Integrated Services Digital Network (B-ISDN) - Digital
30、Subscriber Signalling No. 2 (DSS2) - Point-point multiconnection callrelated bearer control protocolDraft ITU-T Rec. Q.29cc-ROSE Broadband Integrated Services Digital Network (B-ISDN) - Call controlprotocolDraft ITU-T TRQ-2001 General aspects for the development of unified signalling requirements3 A
31、cronymsAESA ATM End System AddressAFI Authority and Format IdentifierATM Asynchronous Transfer ModeB-HLI Broadband High Layer InformationB-ISDN Broadband ISDNB-ISUP Broadband ISDN User PartB-PISN Broadband PISNDCC Designated Country CodeGFP Generic Functional ProtocolGFT Generic Functional Transport
32、GSM Global System MobileGSTN General Switched Telephony NetworkICD International Code DesignatorIN Intelligent NetworkIP Internet ProtocolISDN Integrated Services Digital NetworkLAN Local Area NetworkLANE LAN EmulationMC Multipoint ControllerMCU Multipoint Control UnitMIB Management Information Base
33、MP Multipoint ProcessorMPLS Multi-Protocol Label Switching- 3 -MPOA Multi-Protocol Over ATMNSAP Network Service Access PointPISN Private Integrated Services NetworkPNNI Private Network-Network InterfacePNP Private Numbering PlanPUM Private Personal MobilityPVC Permanent Virtual CircuitQoS Quality of
34、 ServiceRTCP Real-Time Control ProtocolRTP Real-Time ProtocolSCN Switched Circuit NetworkSDP Session Description ProtocolSIP Session-Initiated ProtocolSNMP Simple Network Management ProtocolSVC Switched Virtual CircuitTCP Transmission Control ProtocolTE Terminal EquipmentUDP User Datagram ProtocolUI
35、M User Identification ModuleUPT Universal Personal TelephonyURL Universal Resource LocatorVHE Virtual Home Environment4 Introduction4.1 Overview of H.323 and related recommendations4.1.1 H.323 concept and entitiesH.323 specifies multimedia conferencing over packet networks. This sentence already con
36、tains thekeywords for noting major characteristics of H.323:G01 Multimedia - The media mix in a call can consist of audio, video and data streams. Audiocommunication must be supported, video and data are optional. Media can be added, dropped orreplaced dynamically during a call.NOTEA telefax service
37、 is being drafted for the next version of H.323.G01 Conference - Even a two-party call is considered a special case of a multiparty conference. Withregard to audio or video, multipoint conferencing can be centralized (media processing is done by acentral multipoint processor, MP), decentralized (med
38、ia are multicast directly from the sendingparty to all receiving parties), or mixed (combination of the two). Hybrid conferences combiningcentralized audio with decentralized video, or vice versa, are possible. Control information isalways centralized via a multipoint controller (MC). Data traffic i
39、s also distributed centrally.G01 Packet network - Although H.323 is independent of the specific transport substructure, its mainsphere seems to be TCP/IP based networks (LANs/intranets or internet). The network provides atransparent transport service between communicating entities, i.e. the entities
40、 communicate end-to-end without any ”exchange” or ”switch” between them.H.323 entities are terminals, gateways, gatekeepers, MCs, MPs and multipoint control units (MCUs).An MCU consists of an MC and optionally one or more MPs.Terminals, gateways and MCUs are endpoints, which can place and accept cal
41、ls (i.e., they are”callable”).A gatekeeper is not an endpoint and is ”addressable” but not callable. It performs for endpoints in its”zone” tasks such as address resolution, admission control and bandwidth control.MCs and MPs are neither addressable nor callable, but will be part of an endpoint or g
42、atekeeper whichis addressable/callable.- 4 -H.323 uses the terms call and conference in the following way:G02 A call is the point-to-point multimedia communication between two H.323 endpoints, either direct orvia gatekeeper(s) and/or MC(s). In case of interworking, the H.323 call consists of the sec
43、tionbetween the gateway and another H.323 endpoint.G02 A point-to-point conference is the multimedia communication between two terminals irrespective oftheir location. In case of interworking, it contains a section between the gateway and another H.323endpoint and also a section in the other network
44、.G02 A multiparty conference is the multimedia communication between three or more terminalsirrespective of their location, but including at least one MC. A point-to-point conference becomes amultiparty conference by adding parties, and vice versa by dropping parties.NOTEThe term conference in H.323
45、 corresponds to the term session in the B-ISDN information model.4.1.2 Channels defined in H.323H.323 uses the concept of channels to structure the information exchange between communicatingentities. The following channels are part of the communication process:G01 Call signalling channel. This relia
46、ble channel carries information for call control andsupplementary service control. The Q.931-like protocol used over this channel is specified inH.225.0 and in H.450.x (for supplementary services).G01 H.245 control channel. This reliable channel carries the H.245 protocol for media control.G01 RAS c
47、hannel. This unreliable channel provides for communication between an endpoint and itsgatekeeper. The RAS (Registration, Admission and Status) protocol is specified in H.225.0.G01 Logical channels for media. Usually each real-time medium is carried in a separate pair ofunidirectional unreliable chan
48、nels, one for each direction, using the RTP and RTCP protocols. Acall with audio and video therefore involves at least four logical channels. Data traffic, however,uses a bi-directional reliable channel and a protocol stack according to T.120.In this list, a reliable channel means connection-mode tr
49、ansport, while unreliable refers toconnectionless transport. In an IP-based scenario, this corresponds to TCP and UDP, respectively.Annex C of H.323 provides a means of carrying real-time media information (audio or video) over anATM SVC instead of over UDP/IP when an ATM path exists endstation-to-endstation. This allows thereal-time media to take advantage of the QoS guarantees that ATM provides. Other H.323-relatedprotocols are still carried over TCP/IP or UDP/IP, using an IP/ATM (e.g., MPLS, MPOA, LANE,RFC 1577, RFC 1483) technique. If audio or video is carried over ATM a
