Subject: RE: [Sip] Forking: a modest proposal.

From: "Christian Huitema" <[email-masked]>
Date: Mon, 2 Jul 2001 19:12:22 -0700

> The problem, of course, with requiring a three-way handshake involving
> the response to the method is that forking proxies drop all but the
first
> response (except for INVITEs), so sending a forward indication to
> complete the handshake is impossible. 

This is not quite true. If you require a 3 ways handshake, then the
forking proxy will only carry the first positive response, and will
reject the other ones; but in a 3-ways handshake mode, it should reply
with a "cancel" if it drops a positive response. The positive response
will have to be an ACCK, or very similar. Obviously, if proxies drop all
responses but one, only one responder will receive the ACK; the other
ones would have sent negative responses, or would have receive a cancel,
or would have time out before receiving the ack if the proxy failed to
cancel. The mechanism can be extended to multicast operation.

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---

From: [email-masked]
Date: Tue, 3 Jul 2001 09:54:09 -0500

> -----Original Message-----
> From: Christian Huitema [mailto:[email-masked]]
> 
> with a "cancel" if it drops a positive response. 

What? You lost me there. Who is sending the cancel, and to whom?
The proxy to the subscriber? The proxy to the node receiving the
SUBSCRIBE request? The node receiving the SUBSCRIBE request to the
proxy? The subscriber to the proxy? I can't envision any scenario
in which this makes sense without some radical changes to the way
that SIP works.

> The positive response

I fear you may be speaking from a theoretical standpoint. The prospect
that I would be able to convince anyone to completely rework the way
that SIP proxies operate (and on a method-by-method basis, even) is a
bit overoptimistic.

/a