Subject: [MMUSIC] sdp/nat

From: "Medhavi Bhatia" <[email-masked]>
Date: Wed, 25 Sep 2002 10:56:20 -0400

Hi,

I was looking around for anyone doing work or work in progress to handle
the following nat scenarios:

EP1->OBP1->Proxy->OBP2->EP2.

OBP1, OBP2 are nat/alg devices, also functioning as outbound proxies for
this
scenario. Proxy is a SIP proxy which holds routing/registration information
for EP1 and EP2. EP1 and EP2 are gateways/endpoints in the same addressing
domain (ie., specifically media can flow direct). The aim is to have media
flow direct between EP1 and EP2. OBP1 and OBP2 are two outbound proxies at
the "edge" of the domain. Also, EP1 and EP2 have no mechanisms to determine
what translations will happen on the nats (essentially what this means is
that
the SDP is altered by the OBP1/2 - which also means SMIME is not happening).

The problem is to define a mechanism for direct media. We were working on
enhancing
SDP sent by either OBP1 or EP1 with some new parameters, but I was looking
for
related work in this area.

-Medhavi.