Centralized Conferencing (xcon)

Last modified: 2011-09-26

Additional information is available at Additional XCON Web Page


Real-Time Applications and Infrastructure Area Directors

Real-Time Applications and Infrastructure Area Advisor

Mailing Lists:

General Discussion: xcon@ietf.org
To Subscribe: https://www.ietf.org/mailman/listinfo/xcon
Archive: http://www.ietf.org/mail-archive/web/xcon/

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 (known as a focus) 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 invisible to all but the conference owner, 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.

Due to the centralized architecture of the WG, XCON's mechanisms will place requirements on the signaling protocol used between the focus and the participants. At a high level, the signaling protocol must be able to establish, tear down, modify, and perform call control operations on multimedia streams, including voice, video, and instant messaging, in both a centralized and distributed mixing architecture. SIP will be the reference session signaling protocol used for examples; however, none of the XCON solutions themselves will be signaling protocols, nor will XCON extend existing signaling protocols. Other signaling protocols than SIP may be used between the focus and participants, including non-IETF protocols, but the requirements and possible extensions needed for other signaling protocols to utilize the full functionality of the XCON architecture is outside the scope of XCON.

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, MSEC, 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.

Goals and Milestones

Done Submit Requirements for Basic Floor Control for publication as Informational
Done Submit Conferencing Scenarios document for publication as Informational
Done Submit Basic Floor Control Protocol for publication as PS
Done Submit Framework for publication as PS
Done Submit Event Notification Package for publication as PS
Aug 2009 Submit Conference Data Model for publication as PS
Aug 2009 Submit Conference Control Protocol for publication as PS
Apr 2010 Submit Conferencing Call Flows Document for publication as Informational


Request for Comments

Internet SocietyAMSHome - Tools Team - Datatracker - IASA - IAB - RFC Editor - IANA - IRTF - IETF Trust - ISOC - IETF Journal - Store - Contact Us
Secretariat services provided by Association Management Solutions, LLC (AMS).
Please send problem reports to: ietf-action@ietf.org.