Subject: Re: Query on matching requests to responses at the proxies

From: [email-masked]
Date: Tue, 14 Mar 2000 09:21:42 +0530

Hi,
the issue of matching a request to response is done using the usual From,
To, CallID and CSeq headers, and has
been documented clearly in the  draft .
A proxy, should not insert tags into messages it forwards as tags are only
used for end to end identification (I think
the discussion of branch vs Tags was clearly explained in a previous thread
by Igor and is now a part of the FAQ)

So, if your proxy is forking, it will include a branch-id for each forked
branch - that id, along with the from, to , callid and cseq will identify
req. to responses at the proxy.

I dont see how playing with CSeq acheives a solution to the problem  .

Regds
Arjun

Sunitha Kumar <[email-masked]> on 03/14/2000 10:03:11 AM

To:   SIPbell-labs <[email-masked]>
cc:

Subject:  Query on matching requests to responses at the proxies

How do we match requests to responses at the proxies.( other than the
branch in the Via);
using preferably the fields in a CallLeg, ( so that the call can be
uniquely identified).

Ex: responses to 2 INVITES
Is it legal for the proxy to tag the from field of every request that it
forwards or proxies on, and remove the From tag, when the response to
that comes back, before passing it  downstream.  Making sure, that each
proxy on the way, adds itself to the record route.  So, they are
traversed on the way back.

on other thoughts, what about incrementing the CSeq for every request
that goes out, and decrementing the CSeq , when the response for that
arrives, before passing it downstream.

Any thoughts will help. Thanks much!

--
Sunitha Kumar
Software Engineer
Vovida Networks
(408) 957 - 6374