I have suggested some directions for exploration of solutions to the problem of support of multimedia over the past week, but I suspect such suggestions go beyond my role as WG Chair. Hence I am taking a step backward and simply summarizing the issues for others to resolve.

Issue 1: representation of connection topologies for multiple media types.

It seems to me that contexts are not topologies themselves, but rather represent envelopes within which different topologies will be realized depending on the mode settings for the associated terminations.

Requirements: a) Coordinate between different media streams (e.g. for lip-synch, stereo). b) Represent degenerate cases simply (e.g. audio-only connections, two-point connections). c) Support multicast.

Issue 2: support for different multipoint, medium-specific bridging methods.

For audio, the most obvious bridging method sums all inputs except that of the party to which the signal is being sent. For video, one can have continuous presence, most recent speaker, and probably lots of others.

Issue 3: support for Chair-controlled conferences.

We most assuredly do not want to develop yet another conference control protocol. Nevertheless, we must understand conference control and how it could affect the messaging between the MG and MGC.

Issue 4: support for T.120 multipoint data conferencing service.

T.120 assigns roles to individual nodes within a conference network. Can the MG infer its role from the context cardinality (two-point vs. multipoint), or is additional information required?

Meta-issue: where do Megaco's interests stop and those of SG 16 take over? Are we reaching the stage where some things have to be marked "for further study", or do we work through all the issues now to make sure our base solution will cover all needs?

Tom Taylor E-mail: taylor@nortelnetworks.com (internally Tom-PT Taylor) Tel.: +1 613 765 4167 (internally 395-4167) This is frequently forwarded to my residence.