Subject: [MMUSIC] suggestion for new parameter

From: "Medhavi Bhatia" <[email-masked]>
Date: Tue, 1 Oct 2002 10:53:34 -0400

This is related to: draft-sen-sipping-intrarealm-stun-00.txt.

I wanted to propose a change in the mechanism, by introducing
new sdp parameters.

The basic aim is to allow media to flow directly between two endpoints
which are in the same realm/domain, where the call goes (or is transferred)
through an externam proxy/B2BUA etc.

Whovever is capable of doing nat/stun/other mechanism (client/proxy/B2BUA),
inserts an extra line, m0=<base ip address> <base port> <domain signature>,
where the base ip
address and port represent the original ip/port in the c and m lines,
which are changed for nat purposes. This line can be replaced/deleted
by by another proxy in the chain, who desires that media MUST be routed
through it (in other words, it has control/policy).

When an offer containing this SDP reaches the final proxy (to which the
gateway/endpoint is registered), it determines using m0, that the src
media is originaing in the same domain as the final destination. It
removes the old m and c lines, and introduces new lines based on the
contents
of the m0 line. This procedure can be done at the final destination, if it
supports
the m0 parameter.

In other words, the procedure can be both supported on either the
proxy/B2BUA or the
endpoint itself. The final endpoint either sees the original m/c line (which
are in
its domain) or is able to figure that out if the original m0 line was
present.

Any comments ?

-Medhavi.