ISO IEC 22535-2009 Information technology - Telecommunications and information exchange between systems - Corporate telecommunication networks - Tunnelling of Q.pdf

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1、 Reference number ISO/IEC 22535:2009(E) ISO/IEC 2009INTERNATIONAL STANDARD ISO/IEC 22535 Third edition 2009-04-15 Information technology Telecommunications and information exchange between systems Corporate telecommunication networks Tunnelling of QSIG over SIP Technologies de linformation Tlcommuni

2、cations et change dinformation entre systmes Rseaux de tlcommunications dentreprise Tunnellisation de QSIG sur SIP ISO/IEC 22535:2009(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited

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7、copyrightiso.org Web www.iso.org Published in Switzerland ii ISO/IEC 2009 All rights reservedISO/IEC 22535:2009(E) ISO/IEC 2009 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope 1 2 Normative references 1 3 Terms and definitions .2 4 Abbreviated terms .3 5 Background and archi

8、tecture.3 5.1 Architecture3 5.2 Basic operation4 5.3 QSIG connectionless transport5 5.4 Late availability of SDP parameters at the egress gateway 5 6 Procedures .5 6.1 General5 6.2 Encapsulation of QSIG messages in SIP messages5 6.3 QSIG SETUP message handling at an ingress gateway6 6.3.1 Sending a

9、SIP INVITE request 6 6.3.2 Receipt of responses to the INVITE request.6 6.4 QSIG SETUP message handling at an egress gateway.7 6.4.1 Receiving a SIP INVITE request .7 6.4.2 Rejecting a QSIG message in an INVITE request.8 6.5 Subsequent QSIG messages8 6.6 Terminating the SIP dialog .8 6.7 QSIG connec

10、tionless message handling at an ingress gateway .9 6.7.1 Sending a SIP INVITE request 9 6.7.2 Receipt of responses to the INVITE request.9 6.8 QSIG connectionless message handling at an egress gateway.10 7 Example message sequences10 7.1 Call establishment .10 7.2 Call clearing11 7.3 QSIG connection

11、less message 12 7.4 Call establishment with port=0 in first SDP answer.13 7.5 Backwards compatibility with early editions 14 8 Security considerations 16 Annex A (informative) Changes from early editions17 Bibliography 19 ISO/IEC 22535:2009(E) iv ISO/IEC 2009 All rights reservedForeword ISO (the Int

12、ernational Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International Standards through technical committees establ

13、ished by the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work. In the

14、field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of the joint technical committee is to prepare International Standards. Dr

15、aft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires approval by at least 75 % of the national bodies casting a vote. Attention is drawn to the possibility that some of the elements of thi

16、s document may be the subject of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights. ISO/IEC 22535 was prepared by Ecma International (as ECMA-355) and was adopted, under a special “fast- track procedure”, by Joint Technical Committee ISO/IEC JTC 1

17、, Information technology, in parallel with its approval by national bodies of ISO and IEC. This third edition cancels and replaces the second edition (ISO/IEC 22535:2006), which has been technically revised. ISO/IEC 22535:2009(E) ISO/IEC 2009 All rights reserved v Introduction This International Sta

18、ndard is one of a series of Standards defining the interworking of services and signalling protocols deployed in corporate telecommunication networks (CNs) (also known as enterprise networks). The series uses telecommunication concepts as developed by ITU-T and conforms to the framework of Internati

19、onal Standards on Open Systems Interconnection as defined by ISO/IEC. “QSIG“ is a signalling protocol that operates between Private Integrated services Network eXchanges (PINX) within a Private Integrated Services Network (PISN). A PISN provides circuit-switched basic services and supplementary serv

20、ices to its users. QSIG is specified in Standards, in particular ISO/IEC 11572, ISO/IEC 11582 and a number of Standards specifying individual supplementary services. NOTE The name QSIG was derived from the fact that it is used for signalling at the Q reference point. The Q reference point is a point

21、 of demarcation between two PINXs (ISO/IEC 11572). SIP is an application layer protocol for establishing, terminating and modifying multimedia sessions. It is typically carried over IP (RFC 791), (RFC 2460). Telephone calls are considered as a type of multimedia session where just audio is exchanged

22、. SIP is defined in RFC 3261. Often a CN comprises both PISNs employing QSIG and IP networks employing SIP. A call or call independent signalling can originate at a user connected to a PISN and terminate at a user connected to an IP network or vice versa. In either case, a gateway provides interwork

23、ing between QSIG and SIP at the boundary between the PISN and the IP network. Basic call interworking at a gateway is specified in ISO/IEC 17343. Another case is where a call or call independent signalling originates at a user connected to a PISN, traverses an IP network using SIP, and terminates at

24、 a user connected to another (or another part of the same) PISN. This document addresses this last case in a way that preserves all QSIG capabilities across the IP network. It achieves this by tunnelling QSIG messages within SIP requests and responses in the context of a SIP dialog. This Internation

25、al Standard specifies tunnelling of QSIG over the Session Initiation Protocol (SIP). This enables calls between “islands“ of circuit switched networks that use QSIG signalling to be interconnected by an IP network that uses SIP signalling without loss of QSIG functionality. This International Standa

26、rd facilitates the introduction of enhanced SIP and SDP functionality that was specified after publication of the early editions of this International Standard. These enhancements include payload encryption and mechanisms to negotiate SDP capabilities. The changes in this International Standard comp

27、rise a mandatory payload renegotiation with reversed direction of the offer/answer exchange compared with early editions. In order to achieve backward compatibility with early editions an indicator for the changed signalling procedures is introduced. This indicator is used to dynamically detect if f

28、allback to signalling procedures compliant to early editions is necessary. This International Standard is based upon the practical experience of Ecma member companies and the results of their active and continuous participation in the work of ISO/IEC JTC 1, ITU-T, IETF, ETSI and other international

29、and national standardization bodies. It represents a pragmatic and widely based consensus. INTERNATIONAL STANDARD ISO/IEC 22535:2009(E) ISO/IEC 2009 All rights reserved 1 Information technology Telecommunications and information exchange between systems Corporate telecommunication networks Tunnellin

30、g of QSIG over SIP 1 Scope This International Standard specifies tunnelling of “QSIG“ over the Session Initiation Protocol (SIP) within a corporate telecommunication network (CN). The tunnelling of QSIG through a public IP network employing SIP is outside the scope of this International Standard. Ho

31、wever, the functionality specified in this International Standard is in principle applicable to such a scenario when deployed in conjunction with other relevant functionality (e.g. address translation, security functions, etc.). This International Standard is applicable to any interworking unit that

32、 can act as a gateway between a PISN employing QSIG and a corporate IP network employing SIP, with QSIG tunnelled within SIP requests and responses. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the editio

33、n cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO/IEC 11572:2000, Information technology Telecommunications and information exchange between systems Private Integrated Services Network Circuit mode bearer services Inter-exc

34、hange signalling procedures and protocol ISO/IEC 11582:2002, Information technology Telecommunications and information exchange between systems Private Integrated Services Network Generic functional protocol for the support of supplementary services Inter-exchange signalling procedures and protocol

35、RFC 2119, Key words for use in RFCs to Indicate Requirement Levels, BCP 14, S. Bradner, March 1997 RFC 2976, The SIP INFO Method, S. Donovan, October 2000 RFC 3204, MIME media types for ISUP and QSIG Objects, E. Zimmerer et al., December 2001 RFC 3261, SIP: Session Initiation Protocol, J. Rosenberg

36、et al., June 2002 RFC 3264, An Offer/Answer Model with the Session Description Protocol (SDP), J. Rosenberg, H. Schulzrinne, June 2002 RFC 3840, Indicating User Agent Capabilities in the Session Initiation Protocol (SIP), J. Rosenberg, H. Schulzrinne, P. Kyzivat, August 2004 ISO/IEC 22535:2009(E) 2

37、ISO/IEC 2009 All rights reserved3 Terms and definitions In this document, the key words “MUST“, “MUST NOT“, “REQUIRED“, “SHALL“, “SHALL NOT“, “SHOULD“, “SHOULD NOT“, “RECOMMENDED“, “MAY“, and “OPTIONAL“ are to be interpreted as described in RFC 2119 and indicate requirement levels for compliant SIP

38、implementations. For the purposes of this document, the terms and definitions given in ISO/IEC 11572, RFC 3261 and the following apply. 3.1 corporate telecommunication network CN sets of privately-owned or carrier-provided equipment that are located at geographically dispersed locations and are inte

39、rconnected to provide telecommunication services to a defined group of users NOTE A CN can comprise a PISN, a private IP network (intranet) or a combination of the two. 3.2 egress gateway gateway handling a QSIG call or call-independent signalling connection established in the direction IP network t

40、o PISN 3.3 gateway entity that behaves as a QSIG Transit PINX with QSIG carried over a circuit-switched link within a PISN on one side and QSIG tunnelled over SIP within an IP network on the other side 3.4 ingress gateway gateway handling a QSIG call or call-independent signalling connection establi

41、shed in the direction PISN to IP network 3.5 IP network network, unless otherwise stated a corporate network, offering connectionless packet-mode services based on the Internet Protocol (IP) as the network layer protocol 3.6 media stream audio or other user information transmitted in UDP packets, ty

42、pically containing RTP, in a single direction between the gateway and a peer entity participating in a session established using SIP NOTE Normally a SIP session establishes a pair of media streams, one in each direction. 3.7 Private Integrated Services Network PISN CN or part of a CN that employs ci

43、rcuit-switched technology and QSIG signalling 3.8 Private Integrated Services Network eXchange PINX PISN nodal entity comprising switching and call handling functions and supporting QSIG signalling in accordance with ISO/IEC 11572 ISO/IEC 22535:2009(E) ISO/IEC 2009 All rights reserved 3 4 Abbreviate

44、d terms CN corporate telecommunication network IP Internet Protocol PINX Private Integrated services Network eXchange PISN Private Integrated Services Network QSIG signalling system for the Q reference point RTP Real-time Transport Protocol SDP Session Description Protocol SIP Session Initiation Pro

45、tocol TCP Transmission Control Protocol TLS Transport Layer Security UA User Agent UAC User Agent Client UAS User Agent Server UDP User Datagram Protocol URI Universal Resource Identifier 5 Background and architecture 5.1 Architecture This document concerns the case of a call or call independent sig

46、nalling that originates at a user connected to a PISN employing QSIG, traverses an IP network employing SIP, and terminates at a user connected to another (or another part of the same) PISN. This can be achieved by employing a gateway at each boundary between a PISN employing QSIG and an IP network

47、employing SIP, as shown in Figure 1. Figure 1 Call from QSIG via SIP to QSIG Each gateway can provide interworking as specified in ISO/IEC 17343. This provides a basic call capability. However, ISO/IEC 17343 only specifies interworking for QSIG basic call, as specified in ISO/IEC 11572. Many of the

48、other capabilities of QSIG (support for supplementary services and additional network features) as ISO/IEC 22535:2009(E) 4 ISO/IEC 2009 All rights reservedspecified in other standards and in vendor-specific specifications are not covered. Some of these additional capabilities of QSIG are suitable fo

49、r interworking with SIP and might be the subject of future Standards or other specifications. Other capabilities of QSIG are unsuitable for interworking with SIP because corresponding capabilities do not exist in SIP or are achieved in ways that are incompatible with QSIG. Therefore interworking at a gateway between QSIG and SIP will be limited to those QSIG capabilities that have sufficiently compatible equivalents in SIP. Each capability requires special implementation in the gateway, and therefore a typic