2.5.9 Multiparty Multimedia Session Control (mmusic)

NOTE: This charter is a snapshot of the 75th IETF Meeting in Stockholm, Sweden. It may now be out-of-date.

Last Modified: 2009-07-23


Joerg Ott <jo@acm.org>
Jean-Francois Mule <jf.mule@cablelabs.com>

Real-time Applications and Infrastructure Area Director(s):

Robert Sparks <rjsparks@nostrum.com>
Cullen Jennings <fluffy@cisco.com>

* The Real-time Applications and Infrastructure Area Directors were seated during the IETF 65.

Real-time Applications and Infrastructure Area Advisor:

Cullen Jennings <fluffy@cisco.com>

Mailing Lists:

General Discussion: mmusic@ietf.org
To Subscribe: mmusic-request@ietf.org
In Body: subscribe your_email_address
Archive: http://www.ietf.org/mail-archive/web/mmusic/index.html

Description of Working Group:

The Multiparty MUltimedia SessIon Control (MMUSIC) Working Group was
chartered to develop protocols to support Internet teleconferencing and
multimedia communications. These protocols are now reasonably mature,
and many have received widespread deployments. The group has revised
some of these protocols in the light of implementation experience and
additional demands that have arisen from other WGs (such as AVT, SIP,
and SIPPING). It is focused on using and negotiating mechanisms such
STUN and TURN in order to enable media sessions to traverse Network
Address Translators NATs, and on new means to exchange SDP capabilities.

Multimedia communications protocols use a common platform to express
media and session descriptions: 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, some of
which were addressed in the revision of SDP. In spite of these, it is
widely deployed.

The current aims of the working group include the following:

- To support the establishment of multi-party multimedia sessions across
NATs, MMUSIC will define an Internet Connectivity Establishment
protocol (ICE). This will define several SDP extensions to work with
NATs for media sessions carried over both UDP and TCP.

- Various extensions to SDP will be pursued to remedy the most urgent of
SDP's shortcomings. These will be limited and include adding support
for limited but generic capability negotiations in SDP, defining the
means to select QoS mechanisms to use for a particular media stream,
enabling file transfer via the SDP Offer/Answer model, and support
media loopback.

With the exception of these specific items, only extensions within the
existing SDP framework will be done (e.g. registering new codecs and
defining parameters for them, extending SDP to include new address

- to maintain and revise the specification of the Real Time Streaming
Protocol (RTSP), including fixes and clarifications based on
implementation experience. The revised RTSP specification will be
re-issued as a Proposed Standard RFC. We will also document how RTSP
can be used in the presence of NAT boxes.

The MMUSIC work items will be pursued in close coordination with other
IETF WGs including AVT, SIP, SIPPING, SIMPLE, XCON, and BEHAVE, as well
as others where appropriate such as NSIS.

Goals and Milestones:

Done  Conduct WG Last Call for SAP Internet-Draft
Done  Submit a revised Internet Multimedia Conferencing Architecture I-D.
Done  Submit a revised SIP I-D.
Done  Submit SDP to the IESG for consideration as a Proposed Standard.
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?)
Done  Submit SDP source filter extensions for Proposed Standard
Done  Submit draft on SDPng motivations, comparisons with current SDP capabilities. Request charter review on SDPng work from IAB and IESG.
Done  Submit SDP security extension for Proposed Standard
Done  Submit IMG requirements and framework for Informational
Done  Submit revised SDP spec for Proposed (or Draft) Standard
Done  Submit SDP Offer/Answer examples for Informational
Done  Review work on IMGs and update charter accordingly
Done  Submit SDP connection-oriented media draft for Proposed Standard
Done  Submit SDPng transition scenarios for Informational
Done  Submit ICE draft for Proposed Standard
Done  Submit updated SDP Offer/Answer examples draft for Informational
Done  Submit SDP Offer/Answer exchange for enabling file transfer as a Proposed Standard
Done  Submit QoS Mechanism Selection in SDP as a Proposed Standard
Done  Submit SDP Capability Negotiations to Proposed Standard
Done  Submit Source-Specific Media Attributes in SDP as Proposed Standard
Done  Submit Connectivity Preconditions for SDP Media Streams as Proposed Standard
Done  Signaling media decoding dependency in SDP
Done  Submit revised RFC for Grouping of Media Lines in SDP
Aug 2009  Submit Considerations for using SDP offer/answer with middleboxes for BCP
Sep 2009  Submit SDP extensions for Media Loopback for Proposed Standard
Sep 2009  Submit SDP Image Attribute as Proposed Standard
Sep 2009  Submit an update to the FEC Grouping Semantics in SDP as Proposed Standard
Oct 2009  Submit ICE-TCP draft as a Proposed Standard
Oct 2009  SDP extensions for Media Capability Negotiations
Nov 2009  Submit SDP extensions for audio media streams over Circuit- Switched bearers as Proposed Standard
Dec 2009  Submit revised RTSP spec for Proposed or Draft Standard (as appropriate)
Dec 2009  Submit RTSP NAT considerations draft
Jan 2010  Submit revised SDP specification to IETF for Proposed Standard


  • draft-ietf-mmusic-rfc2326bis-22.txt
  • draft-ietf-mmusic-rtsp-nat-08.txt
  • draft-ietf-mmusic-ice-19.txt
  • draft-ietf-mmusic-media-loopback-11.txt
  • draft-ietf-mmusic-connectivity-precon-06.txt
  • draft-ietf-mmusic-ice-tcp-08.txt
  • draft-ietf-mmusic-sdp-capability-negotiation-10.txt
  • draft-ietf-mmusic-sdp-media-capabilities-08.txt
  • draft-ietf-mmusic-rfc3388bis-03.txt
  • draft-ietf-mmusic-rfc4756bis-05.txt
  • draft-ietf-mmusic-image-attributes-03.txt
  • draft-ietf-mmusic-sdp-cs-01.txt

    Request For Comments:

    RFC2326 PS Real Time Streaming Protocol (RTSP)
    RFC2327 PS SDP: Session Description Protocol
    RFC2543 PS SIP: Session Initiation Protocol
    RFC2974 E Session Announcement Protocol
    RFC3108 PS Conventions for the use of the Session Description Protocol (SDP)for ATM Bearer Connections
    RFC3259 I A Message Bus for Local Coordiantion
    RFC3264 PS An Offer/Answer Model with SDP
    RFC3266 PS Support for IPv6 in SDP
    RFC3388 PS Grouping of media lines in Session Description Protocol SDP
    RFC3524 PS Mapping of Media Streams to Resource Reservation Flows
    RFC3605 Standard RTCP attribute in SDP
    RFC3890 Standard A Transport Independent Bandwidth Modifier for the Session Description Protocol (SDP)
    RFC4091 Standard The Alternative Network Address Types (ANAT) Semantics for the Session Description Protocol (SDP) Grouping Framework
    RFC4145 Standard TCP-Based Media Transport in the Session Description Protocol (SDP)
    RFC4317 I Session Description Protocol (SDP) Offer/Answer Examples
    RFC4435 I A Framework for the Usage of Internet Media Guides (IMGs)
    RFC4473 I Requirements for Internet Media Guides (IMGs)
    RFC4566 PS SDP: Session Description Protocol
    RFC4567 PS Key Management Extensions for Session Description Protocol (SDP) and Real Time Streaming Protocol (RTSP)
    RFC4568 PS Session Description Protocol Security Descriptions for Media Streams
    RFC4570 PS Session Description Protocol (SDP) Source Filters
    RFC4572 PS Connection-Oriented Media Transport over the Transport Layer Security (TLS) Protocol in the Session Description Protocol (SDP)
    RFC4574 PS The Session Description Protocol (SDP) Label Attribute
    RFC4583 PS Session Description Protocol (SDP) Format for Binary Floor Control Protocol (BFCP) Streams
    RFC4756 PS Forward Error Correction Grouping Semantics in Session Description Protocol
    RFC4796 PS The Session Description Protocol (SDP) Content Attribute
    RFC5027 PS Security Preconditions for Session Description Protocol (SDP) Media Streams
    RFC5432 PS Quality of Service (QoS) Mechanism Selection in the Session Description Protocol (SDP)
    RFC5547 PS A Session Description Protocol (SDP) Offer/Answer Mechanism to Enable File Transfer
    RFC5576 PS Source-Specific Media Attributes in the Session Description Protocol (SDP)
    RFC5583 PS Signaling Media Decoding Dependency in the Session Description Protocol (SDP)

    Meeting Minutes


    Agenda and progress report
    RTSP 2.0
    RTSP Fast Content Switching
    SIP-SDP Overlap with RTSP
    SDP Connectivity Capability
    SDP Attribute for Maximum Media Sources
    Media Source Selection in SDP
    SDP Extensions for audio over PSTN CS bearers
    Misc Capability Negotiation in SDP