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

From: S_S_Dinesh/India/[email-masked]
Date: Mon, 8 May 2000 14:10:23 +0530

Sunitha Kumar wrote:
>
> 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.

Why do this? You'll break authentication and it won't work if a tag was
already there.

>
> 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.

I also highly recommend against this. If the client sends a request with
that same CSeq, which does not pass through your proxy somehow, things
will be mightily confused. Also this doesn't work with authentication.
Why do you want to do this? The spec is quite clear on how responses are
matched to requests. Why does incrementing the CSeq help in any way?

-Jonathan R.

--
Jonathan D. Rosenberg                       200 Executive Drive
Chief Scientist                             Suite 120
dynamicsoft                                 West Orange, NJ 07052
[email-masked]                     FAX:   (732) 741-4778
http://www.cs.columbia.edu/~jdrosen         PHONE: (732) 741-7244
http://www.dynamicsoft.com

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