Subject: Define a unicast RTP session.

From: [email-masked]
Date: Fri, 25 Aug 2000 14:59:27 -0500

Hello,

A simple question:

If there is a single conversation between two RTP implementations, i.e. two
oppositely directed RTP packet flows, using UDP over _unicast_ IP, how many
sessions are there: one or two?

If there are two sessions, does that mean that the sessions are each
defined by one and only one destination transport address pair?  Seems like
the obvious answer would be yes.

If, instead, there is one session, does that mean that the session is
defined by two destination transport address pairs?  Again, the obvious
answer would seem to be yes.  Further, if this is the case, does the
wording of the RFC in the definition of a session allow the destination
port pairs to differ, in addition to the network addresses?

Sincerely,

Vince Virgilio
Natural Microsystems

---

From: Jonathan Rosenberg <[email-masked]>
Date: Sat, 26 Aug 2000 13:54:29 -0400

> sessions are there: one or two?

Two.

> the obvious answer would be yes.

Yes (pair being even,even+1)

Unicast RTP is used extensively by SIP/SDP. Check out the appendices of
rfc2543 which describe SDPs usage for unicast RTP sessions within SIP.

-Jonathan R.

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