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Multiparty Multimedia Session Control (mmusic)

WG Name Multiparty Multimedia Session Control
Acronym mmusic
Area Applications and Real-Time Area (art)
State Active
Charter charter-ietf-mmusic-05 Approved
Document dependencies
Additional resources Issue tracker, Wiki, Zulip Stream
Personnel Chairs Bo Burman, Flemming Andreasen
Area Director Murray Kucherawy
Mailing list Address
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Chat Room address

Charter for Working Group

The Multiparty MUltimedia SessIon Control (MMUSIC) Working Group was
originally chartered to develop protocols to support Internet
teleconferencing and multimedia communications. These protocols are now
reasonably mature, and many have received widespread deployment.
Currently, the group is focused on using and negotiating media streams
with the Session Description Protocol (SDP), which is used as a common
protocol to express media and session descriptions. The group also
maintains the Real-time Streaming Protocol (RTSP) specifications.

The group has revised these protocols in the light of implementation
experience and additional demands that have arisen from other WGs (such
as AVTCORE, CLUE, ICE, and RTCWEB). In particular, the many uses of SDP
have led to requests for numerous extensions as well as a recognition of
several limitations in the original protocol design. Today, the SDP
protocol is widely deployed and continues to see extensions being defined.

The current aims of the working group include the following:

  • Provide SDP signaling support for the Interactive Connectivity
    Establishment (ICE) protocol and its extensions. These were originally
    defined in MMUSIC, but are now handled by the ICE WG.
  • To support the establishment of multi-party multimedia sessions for
    RTCWEB based implementations, MMUSIC provides SDP signaling support for
    a number of extensions required by RTCWEB. The MMUSIC WG will seek a
    balanced trade-off between general applicability of such extensions
    versus RTCWEB specific usage.
  • Various other extensions to SDP may be pursued to remedy the most
    urgent of SDP's shortcomings. These include updates to the SDP
    specification itself and missing IANA registrations.
  • With the exception of the items listed above, only extensions within
    the existing SDP framework will be done.
  • Maintain the specification of the (revised) Real Time Streaming
    Protocol (RTSP) as needed.

The MMUSIC work items will be pursued in close coordination with other
IETF WGs including AVTCORE, CLUE, ICE, RTCWEB and SIPCORE, as well as
others where appropriate.


Date Milestone Associated documents
Jul 2021 Submit Using Multicast DNS to protect privacy when exposing ICE candidates as Informational draft-ietf-mmusic-mdns-ice-candidates

Done milestones

Date Milestone Associated documents
Done Submit RFC 8843bis (Negotiating Media Multiplexing Using the Session Description Protocol (SDP)) as Proposed Standard draft-ietf-mmusic-rfc8843bis
Done Submit SDP Negotiation of MSRP over Data Channels as Proposed Standard draft-ietf-mmusic-msrp-usage-data-channel
Done Submit T.140 Real-time Text Conversation over WebRTC Data Channels as Proposed Standard draft-ietf-mmusic-t140-usage-data-channel
Done Submit Unknown Key Share Attacks on uses of Transport Layer Security with the Session Description Protocol as Proposed Standard
Done Submit Interactive Connectivity Establishment (ICE) with SDP offer/answer and SIP as Proposed Standard
Done Submit SDP Negotiation of DataChannel sub-protocols as Proposed Standard
Done Submit revised SDP specification to IETF as Proposed Standard
Done Submit Using Simulcast in SDP and RTP Sessions as Proposed Standard
Done Submit SIP usage for Trickle ICE as Proposed Standard
Done Submit SDP extensions to negotiate multiplexed media streams as Proposed Standard
Done Submit RTP Payload Format Constraints as Proposed Standard
Done Using the SDP Offer/Answer Mechanism for DTLS
Done Submit SCTP-Based Media Transport in SDP as Proposed Standard.
Done Submit Indicating Exclusive Support of RTP/RTCP Multiplexing using SDP as Proposed Standard
Done Submit SDP extension for cross session stream identification as Proposed Standard
Done Submit IANA registrations of SDP 'proto' attribute for transporting RTP Media over TCP under various RTP profiles as Proposed Standard
Done Submit a framework for SDP attributes when multiplexing as Proposed Standard