Subject: Which service class for a scalable flow ?

From: [email-masked] (Francois Toutain)
Date: Tue, 2 Jul 96 14:20:19 +0200

Hi,

Since the list is relatively quiet these days, I take the opportunity
to submit the following question.
Consider a scalable continuous data flow, for instance a hierarchical
video stream. Say the whole stream is made of a dozen subbands, which
gradually improve the perceived quality when combined together.
Assume the stream comes from a real-time device, and is used in an
interactive multimedia application. The users requirements are real-time
delivery, because of interactivity, best possible quality (i.e.
number of subbands), and guaranteed, lossless delivery of the baseband, 
so as to avoid call interruption.

My question is: given the current service classes being discussed, how
could such a stream be properly handled ? Are additional assumptions
needed ? (eg. token bucket conformance for the baseband...)

Thanks a lot for your answers and comments.

Francois

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From: [email-masked] (Andrew T. Campbell)
Date: Tue, 2 Jul 1996 13:05:36 -0400 (EDT)

Francois:

Geoff Coulson and I addressed the "multi-layer/multicast/QoS distribution
problem" as a part of a suite of mechanisms for QoS adaption in ATM
networks. Being unconstrained by  IETF/ATM Forum prescribed services
we developed a distributed QoS adaption service specifically for the task. 
We implemented it in the end-systems (Linux) and ATM switches (ORL 4x4s) 
and used MPEG to demonstrate distribution of multi-layer coded video 
to different members of a multicast group using a native ATM transport. 
The results were interesting - even if the scheme has some scaling problems. 
You can get a copy of the technical report describing this work at:

http://www.ctr.columbia.edu/~campbell/papers/adapt.ps.gz

If my memory services me right there is a paper by Van J. and Steve M. 
on "delivery of multi-layer coded flows over the Internet" to be
presented at SIGCOMM`96 ? The results from this work may address your 
specific questions more directly.

Best,
-- 
Andrew
http://www.ctr.columbia.edu/~campbell
(212)-854-3109