SIPPING Working Group Y. Ma H.Ikeda H.Deng Internet-Draft Hitachi (China) Expires: January 11, 2006 July 10, 2005 Requirements for the interworking between IPv4-based H.323 system and IPv6-based SIP conference system draft-ma-h323-sip-conf-requirement-00.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on January 11, 2006. Copyright Notice Copyright (C) The Internet Society (2005). Abstract H.323 conference system is well defined and widely deployed today. It is important for SIP UA, both IPv4 and IPv6, to access H.323 conference system. This document defines an architecture for a SIP UA to access H.323 conference system. The requirements for the elements in this architecture are examined. Also the transition scenario for IPv6 SIP UA to access IPv4 H.323 conference system is discussed. Ma Expires January 11, 2006 [Page 1] Internet-Draft Interworking between H.323 and SIP July 2005 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. General architecture . . . . . . . . . . . . . . . . . . . . . 5 4. Signaling Layer . . . . . . . . . . . . . . . . . . . . . . . 6 4.1 Alias Mapping . . . . . . . . . . . . . . . . . . . . . . 6 4.2 Message Mapping . . . . . . . . . . . . . . . . . . . . . 6 4.3 Conference Control . . . . . . . . . . . . . . . . . . . . 6 4.4 Floor control . . . . . . . . . . . . . . . . . . . . . . 7 4.5 IPv4/IPv6 transition . . . . . . . . . . . . . . . . . . . 7 5. The Media Layer . . . . . . . . . . . . . . . . . . . . . . . 8 5.1 IPv4/IPv4 . . . . . . . . . . . . . . . . . . . . . . . . 8 5.2 IPv4/IPv6 transition . . . . . . . . . . . . . . . . . . . 8 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 8.1 Normative References . . . . . . . . . . . . . . . . . . . 11 8.2 Informative References . . . . . . . . . . . . . . . . . . 11 Author's Address . . . . . . . . . . . . . . . . . . . . . . . 12 Intellectual Property and Copyright Statements . . . . . . . . 13 Ma Expires January 11, 2006 [Page 2] Internet-Draft Interworking between H.323 and SIP July 2005 1. Introduction H.323 conference system is well defined and widely deployed today. SIPPING WG is also defining tightly coupled SIP conferencing now[CONFFM][CCCONF]. It is important for the two conference system to interoperate with each other. In addition, H.323 conference system deployed today is IPv4 only. As for SIP, both IPv4 and IPv6 elements have been implemented. It is necessary for IPv6 SIP system to communicate with IPv4 H.323 conference system. There are two scenarios for the two systems to communicate with each other depending on the location of the conference control unit. One is that the conference control unit locates in H.323 network, a SIP UA joins the conference through some methods. The other is that the conference control unit locates in SIP network. H.323 terminal joins a SIP conference defined in [CONFFM]. This document will focus on the scenario where the conferenceing control function locates in H.323 conference system. This document defines an architecture for a SIP UA, both IPv4 and IPv6, to access H.323 conference system. The requirements for the entities in this architecture are examined. For the two conference system to interoperate with each other the signaling needs to be translated. Further more, for IPv6 SIP UA to access IPv4 H.323 system media layer also needs to be manipulated. Section 3 describe the architecture for the interoperation. Section 4 discusses the signalig layer. Section 5 disscusses the media layer. Ma Expires January 11, 2006 [Page 3] Internet-Draft Interworking between H.323 and SIP July 2005 2. Terminology In this document, the key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in BCP 14, [RFC2119] and indicate requirement levels for compliant implementations. Ma Expires January 11, 2006 [Page 4] Internet-Draft Interworking between H.323 and SIP July 2005 3. General architecture The requirement for SIP-H.323 interworking is defined in [RFC4123]. Common architectures involving an IWF are introduced int the domument. For the two conference system to interoperate with each other, the architecture is shown in Figure 1. The IWF is the interworking unit for the two systems. The MCU is the conference control unit in H.323 system. The IWF communicates with MCU through H.323 GK. The SIP UA communicates with IWF through SIP proxy. With the help of IWF a SIP UA can join an H.323 conference maintained in MCU. The IWF is interworking function unit. It is in charge of signaling layer interoperation. _____ ________ ____ -->| SIP |<->| IWF |<->| |<--- / |Proxy| | | | GK | \ | |_____| |________| |____| | | |^ ^| | _____________ | || || \->| MCU within | | || || |H.323 domain| ______ | || || |____________| | |<-/ _v|____|v_ | | | | | ______|_____ |SIP UA|<-------------->| NAT |<-------------->| media | | | |__________| | server | |______|<------------------------------------------>|__________| Fig.1 Interworking architecture The SIP UA needs to transmit media with media server. If both use global reachable IPv4 address, the media can be transmitted directly after the negotiation process in the call set up procedure. If the SIP UA is IPv6 only and MCU is IPv4 only they need to communicate through a NAT. Ma Expires January 11, 2006 [Page 5] Internet-Draft Interworking between H.323 and SIP July 2005 4. Signaling Layer The IWF works for signaling interoperation. In H.323 domain the IWF registers to the GK as a GW end point. In SIP domain it is a focus UA as defined in [CONFFM][CCCONF]. The floor control server is the H.323 MCU. The floor chairs also reside in the H.323 domain. The SIP UA in this conference is just common participant. Other scenarios are out of the scope of this document. 4.1 Alias Mapping There are different formats of alias addresses in H.323 and the corresponding addresses in SIP. H.323 supports different types of alias addresses. The IWF should support all the types of alias addresses. The IWF MUST support alias mapping. It MUST have means to map SIP URI to H.323 alias address and vice versa. 4.2 Message Mapping The IWF MUST map SIP messages to H.323 messages and vice versa. 4.3 Conference Control In SIP domain the IWF behaves as a focus. A focus, as defined in [CONFFM], maintains a SIP signaling relationship with each participant in the conference. The IWF SHOULD support the conference package, behave as a notifier for that package, and indicate its support in the Allow- Events header fields in requests and responses. A globally routable Conference Factory URI can be allocated and published for the IWF. When the UA calls the conference factory URI, a new conference is created through interaction with MCU. Ma Expires January 11, 2006 [Page 6] Internet-Draft Interworking between H.323 and SIP July 2005 When other URI is called, the call is routed to GK to find correspondent conference. 4.4 Floor control Floor control is well defined in H.323 system[H.323]. [H.248.19] defines the floor control package between MC and MP. The IWF MUST support floor control protocol in H.323. In XCON [BFCP] is defined. The SDP for BFCP[SDPBFCP] is defined in MMUSIC. The IWF MUST support floor control in SIP message. The IWF MUST map H.323 floor control to BFCP in SIP message and vice versa. 4.5 IPv4/IPv6 transition The IPv4/IPv6 transition in signaling layer is done by the IWF. all the signaling should be transmitted through the IWF. The IWF should understand the format of both IPv4 and IPv6 address. For address translation it SHOULD support NAT traversal[NAT]. Ma Expires January 11, 2006 [Page 7] Internet-Draft Interworking between H.323 and SIP July 2005 5. The Media Layer The media layer has two cases. In the first case both SIP UA and H.323 MCU have IPv4 addresses. In the second case the SIP UA is in IPv6 network while the H.323 MCU is in IPv4 network. In the second case a NAT is needed to translate media stream. 5.1 IPv4/IPv4 In this scenario the SIP UA and H.323 MCU can exchange RTP stream directly after SDP/H.245 negotiation. The IWF MUST support SDP/H.245 mapping. If NAT exists in the media path the UA can use STUN or other means to traverse the NAT. 5.2 IPv4/IPv6 transition In this scenario a NAT is necessary to translate IPv4 address to IPv6 address and vice versa. For terminals to communicate with each other the IWF should support MIDCOM[RFC3303]. It behaves as a MIDCOM agent. With the information extracted from SDP/H.245 it MUST notify the NAT to enable media transmission through NAT device. Ma Expires January 11, 2006 [Page 8] Internet-Draft Interworking between H.323 and SIP July 2005 6. IANA Considerations There are no IANA considerations associated with this specification. Ma Expires January 11, 2006 [Page 9] Internet-Draft Interworking between H.323 and SIP July 2005 7. Security Considerations As an interworking entity the IWF should be compliant to the security requirements defined in [RFC4123]. Ma Expires January 11, 2006 [Page 10] Internet-Draft Interworking between H.323 and SIP July 2005 8. References 8.1 Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [H.323] International Telecommunication Union, "Packet based multimedia communication systems", Recommendation H.323, July 2003. [RFC4123] Schulzrinne, H., C. Agboh, "Session Initiation Protocol (SIP)-H.323 Interworking Requirements", RFC 4123, July 2005. 8.2 Informative References [BFCP] Camarillo, G., "The Binary Floor Control Protocol (BFCP)", draft-ietf-xcon-bfcp-04 (work in progress), May 2005. [SDPBFCP] Camarillo, G., "Session Description Protocol (SDP) Format for Binary Floor Control Protocol (BFCP) Streams", draft-ietf-mmusic-sdp-bfcp-01 (work in progress), May 2005. [CCCONF] Johnston, A. and O. Levin, "Session Initiation Protocol Call Control - Conferencing for User Agents", draft-ietf-sipping-cc-conferencing-07 (work in progress), June 2005. [CONFFM] Rosenberg, J., "A Framework for Conferencing with the Session Initiation Protocol", draft-ietf-sipping-conferencing-framework-05 (work in progress), May 2005. [NAT] Boulton, C. and J. Rosenberg, "Best Current Practices for NAT Traversal for SIP", draft-ietf-sipping-nat-scenarios-02 (work in progress), February 2005. Ma Expires January 11, 2006 [Page 11] Internet-Draft Interworking between H.323 and SIP July 2005 [RFC3303] Srisuresh, P., Kuthan, J., Rosenberg, J., Molitor, A., and A. Rayhan, "Middlebox communication architecture and framework", RFC 3303, August 2002. [H.248.19] International Telecommunication Union, "Gateway control protocol: Decomposed multipoint control unit, audio, video and data conferencing packages", Recommendation H.248.19, March 2004. Author's Address Yuanchen Ma Hitachi (China) R&D No. 5 Dong San Huan Bei Lu Road Chaoyang District Beijing 100004 China Phone: +86 10 6590 8111 Email: ycma@hitachi.cn Hiroki Ikeda Hitachi (China) R&D No. 5 Dong San Huan Bei Lu Road Chaoyang District Beijing 100004 China Phone: +86 10 6590 8111 Email: hikeda@hitachi.cn Hui Deng Hitachi (China) R&D No. 5 Dong San Huan Bei Lu Road Chaoyang District Beijing 100004 China Phone: +86 10 6590 8111 Email: hdeng@hitachi.cn Ma Expires January 11, 2006 [Page 12] Internet-Draft Interworking between H.323 and SIP July 2005 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. 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