Subject: WG Action: RECHARTER: Multiparty Multimedia Session Control (mmusic)

From: The IESG <[email-masked]>
Date: Thu, 29 Jul 2004 14:37:24 -0400

The charter of the Multiparty Multimedia Session Control (mmusic) working group 
in the Transport Area of the IETF has been updated. For additional information, 
please contact the Area Directors or the working group Chairs. 

Multiparty Multimedia Session Control (mmusic)
----------------------------------------------

Current Status: Active Working Group

Chairs:
Joerg Ott <[email-masked]>
Colin Perkins <[email-masked]>

Transport Area Directors:
Allison Mankin <[email-masked]>
Jon Peterson <[email-masked]>

Transport Area Advisor:
Jon Peterson <[email-masked]>

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Description of the 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 deployment. The group is
now focussed on the revisions of these protocols in the light of
implementation experience and additional demands that have arisen
from other WGs (such as AVT, SIP, SIPPING, and MEGACO).

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.
In spite of these, it is widely deployed.

- To support this current deployment, MMUSIC will revise SDP
suitable for publication as a Draft Standard RFC. This will
involve correcting minor bugs and clarifying the current
specification.

- Various extensions to SDP will be pursued to remedy the most
urgent of SDP's shortcomings. These will be limited to use of
SDP in conjunction with connection-oriented media such as TCP
and SCTP, offering support to work with NATs and firewalls
(e.g. via the ICE methodology), and exchange of media session
security keys.

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
families).

To address the more fundamental issues with SDP, a next generation of
SDP, referred to as SDPng, will be needed. An initial proposal is now
available, and will be progressed to Experimental RFC while we gain
experience with implementations. An informational document will be
produced describing how the transition to a new session description
protocol can be managed, to prepare implementors for such a future
change.

MMUSIC will 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.

An Internet Media Guide (IMG) is a collection of multimedia session
descriptions expressed using SDP or some other session description
format. It is used to describe a collection of multimedia sessions
(e.g. television programme schedules). The IMG must be delivered to
a potentially large audience, who use it to join a subset of the
sessions described, and who may need to be notified of changes to the
IMG.

MMUSIC will investigate delivery mechanisms for IMGs, generalizing
our work on session announcement and discovery protocols (SAP, RTSP,
SIP). We will investigate and document requirements for IMG delivery
mechanisms, and identify the requirements that these delivery
mechanisms impose on the session description formats used by the IMG.
We will then work to produce a framework document outlining the use
of (existing) protocols to create an IMG delivery infrastructure.
After successful completion of these initial milestones for IMG
delivery, the MMUSIC working group will decide whether or not MMUSIC
is the proper place to pursue any needed mechanisms for IMGs, and if
so, recharter accordingly

The MMUSIC work items will be pursued in close coordination with other
IETF WGs related to multimedia conferencing and IP telephony (AVT, SIP,
SIPPING, SIMPLE, XCON, MEGACO and, where appropriate, MIDCOM and NSIS).
Where appropriate, new separate working groups may 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:

Jun 04 Submit IMG requirements and framework for Informational
Aug 04 Review work on IMGs and update charter accordingly
Aug 04 Submit revised SDP spec for Proposed Standard
Aug 04 Submit SDP Offer/Answer examples for Informational
Sep 04 Submit SDP connection-oriented media draft for Proposed Standard
Nov 04 Submit SDPng transition scenarios for Informational
Nov 04 Submit SDPng base specification for Experimental
Nov 04 Submit ICE draft for Proposed Standard
Feb 05 Submit revised RTSP spec for Proposed Standard
May 05 Submit RTSP NAT considerations draft
Jul 05 Consider update of SDP specification for draft standard
Dec 05 Submit updated SDP Offer/Answer examples draft for Informational

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