Issues Around Support of Multimedia

Tom-PT Taylor taylor at NORTELNETWORKS.COM
Mon Apr 5 12:09:14 EDT 1999

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.

  a) Coordinate between different media streams (e.g. for lip-synch,
  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 at  (internally Tom-PT Taylor)
Tel.: +1 613 765 4167     (internally 395-4167)
  This is frequently forwarded to my residence.

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