Current Meeting Report

2.7.9 Multiparty Multimedia Session Control (mmusic)

NOTE: This charter is a snapshot of the 53rd IETF Meeting in Minneapolis, MN USA. It may now be out-of-date. Last Modified: 05-Mar-02
Joerg Ott <>
Colin Perkins <>
Transport Area Director(s):
Scott Bradner <>
Allison Mankin <>
Transport Area Advisor:
Allison Mankin <>
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Description of Working Group:
The Multiparty MUltimedia SessIon Control (MMUSIC) Working Group (WG) was chartered to develop protocols to support Internet teleconferencing sessions.  These protocols are now reasonably mature, and many of them have received widespread deployment. MMUSIC is now focussing on the revisions of these in the light of implementation experience and additional demands that have arisen from other WGs (such as AVT, SIP, SIPPING, and MEGACO).

All types of multimedia communications are based upon a common platform for expressing media streams (session) descriptions. This is the session description protocol, SDP. The many uses of SDP have led to (requests for) numerous extensions, and have led to recognition of several flaws in the protocol design for key applications of SDP. MMUSIC will revise the SDP specification suitable for publication as a draft standard to address minor revision and further support the current broad deployment. Work on an SDP MIB will be considered.

Various extensions to SDP will be pursued to remedy the most urgent of SDP's shortcomings: However, these are limited to, adding means for identifying and semantically grouping media sessions, providing limited expressiveness for simultaneous capabilities, use of SDP in conjunction with connection-oriented media such as TCP and SCTP, offering support to work with NATs and firewalls, and documenting the use of SDP in SIP as a separate document. Existing key exchange per media session in SDP will be cleaned up in a revision of that portion of RFCxxxx. Apart from these, which are explicitly agreed to by the Area Directors and shown in the milestones, only extensions within the existing framework of SDP will be done -- such as registering new codecs and defining parameters for them extending SDP to include new address families.

To address the more fundamental issues with SDP, a next generation of SDP -- referred to as SDPng -- has been in progress and will be continued towards a standards track document. A requirements document will be devised that gathers the individual requirements from the areas in which SDP is currently deployed. Work on an SDPng MIB will be considered.

MMUSIC will continue to maintain and revise the specification of the Real Time Streaming Protocol (RTSP) based on implementation experience.  The RTSP spec will be revised to include various fixes and clarifications. Depending on the changes, the revised RTSP spec will be re-issued as Proposed or go to Draft Standard.  A MIB will also be defined.

The WG's work items will be pursued in close coordination with other IETF WGs related to multimedia conferencing and IP telephony (AVT, SIP, SIPPING, IPTEL, MEGACO). Where appropriate, new separate working groups will be split off (as has happened with the SIP WG).

The Working Group is also charged with addressing security issues related to the protocols it develops.

Goals and Milestones:
Done   Submit SDP to the IESG for consideration as a Proposed Standard.
Done   Conduct WG Last Call for SAP Internet-Draft
Done   Submit a revised SIP I-D.
Done   Submit a revised Internet Multimedia Conferencing Architecture I-D.
Done   Submit SAP Internet-Draft to IESG for publication as an Experimental Protocol.
Done   Conduct WG Last Call for RTSP Internet-Draft.
Done   Submit Internet-Draft on Internet Multimedia Conferencing Architecture.
Done   Submit RTSP to IESG for consideration as a Proposed Standard.
Done   Conduct WG Last Call for SIP Internet-Draft.
Done   Submit SIP Internet-Draft to IESG for consideration as a Proposed Standard.
Done   Conduct WG Last Call for SAP Security Internet-Draft.
Done   Conduct second WG Last Call for SAP.
Done   Submit SAP Internet-Draft to IESG for consideration as a Proposed Standard.
Done   Submit SAP Security Internet-Draft to IESG for consideration as a Proposed Standard.
Done   Submit IPv6 Extensions to SDP for Proposed Standard
Done   Submit SIP's offer/answer use of SDP for Proposed Standard
Done   Submit SDP4NAT for Proposed Standard (Informational?)
Feb 02   Submit revised SDP spec for Proposed (or Draft) Standard
Feb 02   Submit draft on SDPng motivations, comparisons with current SDP capabilities. Request charter review on SDPng work from IAB and IESG.
Mar 02   Submit SDP key management for Proposed Standard
Apr 02   `Submit SDPng base spec and audio profile for Proposed Standard
May 02   Submit revised RTSP spec for Proposed or Draft Standard (as appropriate)
Jun 02   Submit SDPng video profile spec for Proposed Standard
Jul 02   Submit RTSP MIB for Proposed Standard
Jul 02   Conclude WG
Request For Comments:
RFC2326PSReal Time Streaming Protocol (RTSP)
RFC2327PSSDP: Session Description Protocol
RFC2543PSSIP: Session Initiation Protocol
RFC2974E Session Announcement Protocol
RFC3108PSConventions for the use of the Session Description Protocol (SDP)for ATM Bearer Connections

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