Subject: [Sip] Overlapping REGISTER

From: Loh Kok Jeng <[email-masked]>
Date: Wed, 25 Sep 2002 19:09:53 +0800

Dear all,

In RFC3261, page 58:

      Call-ID: All registrations from a UAC SHOULD use the same Call-ID
           header field value for registrations sent to a particular
           registrar.

           If the same client were to use different Call-ID values, a
           registrar could not detect whether a delayed REGISTER request
           might have arrived out of order.

   ....

   UAs MUST NOT send a new registration (that is, containing new Contact
   header field values, as opposed to a retransmission) until they have
   received a final response from the registrar for the previous one or
   the previous REGISTER request has timed out.

If a stateful proxy receive multiple REGISTER with the same Call-ID (but
different From, To, and Contact) from the same UAC before it receives the
final response, how should it handle these REGISTER messages?  According to
the above paragraphs, this is not allowed.

regards,
KJ Loh

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---

From: Jonathan Rosenberg <[email-masked]>
Date: Mon, 30 Sep 2002 01:40:46 -0400

inline.

> the above paragraphs, this is not allowed.

This is an unusual case. The spec does prohibit a client from sending 
it. However, there is actually nothing wrong with this scenario, and the 
regular server processing in 10.3 will do the right thing. If the To 
field changes between the two registrations, the ordering is no longer 
relevant in terms of the processing of the two transactions - they refer 
to different addresses of record. It is totally irrelevant in this case 
that they happen to come from the same UA.

-Jonathan R.

-- 
Jonathan D. Rosenberg, Ph.D.                72 Eagle Rock Ave.
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