Subject: [AVTCORE] Regarding the discussion of single transport flow with one or more RTP session

From: Magnus Westerlund <[email-masked]>
Date: Fri, 16 Mar 2012 16:57:51 +0100

WG,
(As Individual)

In Paris we will once more have some discussion around what work to do
when it comes to using a single transport flow for one or more RTP
sessions and where an RTP sessions could contain multiple media types.

There are a lot of details to consider in this discussion. I therefore
would strongly encourage anyone who intended to participate in this
discussion to actual prepare and review the available material. I think
the following drafts are all relevant to this discussion and should be
considered:

https://datatracker.ietf.org/doc/draft-westerlund-avtcore-multiplex-architecture/

https://datatracker.ietf.org/doc/draft-westerlund-avtcore-transport-multiplexing/

https://datatracker.ietf.org/doc/draft-alvestrand-rtp-sess-neutral/

https://datatracker.ietf.org/doc/draft-lennox-rtcweb-rtp-media-type-mux/

After quite some consideration I personally will argue for working on
both single RTP session with multiple media types and a mechanism for
multiplexing multiple RTP sessions over a single transport.

The main reasons is that I believe that multiple media types in one RTP
session will be used by some for which the limitations documented in
Section 6.7 of draft-westerlund-avtcore-multiplex-architecture is not an
issue. And unless we document these limitations more than one RTP
application implementor may become very unhappy when they realize them.
So I rather ensure that they are written up. If we are not developing a
mechanism that allows multiple RTP sessions over a single lower layer
transport the WG is blocking the usage of a tool in the RTP toolbox that
we ourself in the past quite frequently have used to accomplish
extensions or functions when it is desirable to have only one transport
flow. That appears short sighted and also provides an implicit
recommendations for multiple media types in a single RTP session despite
its limitations.

Hoping for a fruitful discussion in Paris

Cheers

Magnus Westerlund

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