Subject: WG Review: Centralized Conferencing (xcon)

From: The IESG <[email-masked]>
Date: Mon, 11 Aug 2003 15:34:17 -0400

A new IETF working group has been proposed in the Transport Area.
The IESG has not made any determination as yet.
The following description was submitted, and is provided
for informational purposes only:

Centralized Conferencing (xcon)
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Current Status: Proposed Working Group

Description of Working Group:

The focus of this working group is to develop a standardized suite of
protocols for tightly-coupled multimedia conferences, where strong
security and authorization requirements are integral to the solution.
Tightly-coupled conferences have a central point of control and
authorization so they can enforce specific media and membership
relationships, and provide an accurate roster of participants. The media
mixing or combining function of a tightly-coupled conference need not be
performed centrally, however.

The scope of this effort is intentionally more narrow than previous
attempts to standardize conferencing (e.g. centralized control), and is
intended to enable interoperability in a commercial environment which
already has a number of non-standard implementations using some of the
protocols.

Privacy, security, and authorization mechanisms are integral to the
solution generated by the working group. This includes allowing
participants to be completely invisible or to be visible but participate
anonymously with respect to some or all of the other participants.
Authorization rules allow for participants and non-participants to have
roles (ex: speaker, moderator, owner), and to be otherwise authorized to
perform membership and media manipulation for or on behalf of other
participants. In order to preserve these properties, the protocols used
will require implementation of channel security and authentication
services.

Initially this combination of protocols will be specified with respect
to session setup with SIP. The solutions developed in XCON will not
preclude operation with other signaling protocols; however it is
anticipated that the use of other protocols would require modifications
which are out of scope for this working group.

None of the protocols defined by this group will be SIP, although the
SIP specific event notification framework will be used. The group will
use the high-level requirements and framework already described by documents
published by the SIPPING WG.

The deliverables for the group will be:
- - A mechanism for membership and authorization control
- - A mechanism to manipulate and describe media "mixing" or "topology"
for multiple media types (audio, video, text)
- - A mechanism for notification of conference related events/changes
(for example a floor change)
- - A basic floor control protocol
The initial set of protocols will be developed for use in unicast media
conferences. The working group will perform a second round of work to
enhance the set of protocols as necessary for use with multicast media
after their initial publication.
The following items are specifically out-of-scope:
- - Voting
- - Fully distributed conferences
- - Loosely-coupled conferences (no central point of control)
- - Far-end device control
- - Protocol used between the conference controller and the mixer(s)
- - Capabilities negotiation of the mixer(s)
- - Master-slave cascaded conferences
The working group will coordinate closely with the SIPPING and MMUSIC
working groups. In addition the working group will cooperate with other
groups as needed, including SIP, AVT, and the W3C SMIL working groups.
In addition, the working group will consider a number of existing drafts
as input to the working group.