Subject: [Sip] SIP session timer

From: feng zhang <[email-masked]>
Date: Tue, 20 Aug 2002 20:32:23 +0800

Hi All,

  I'm reading draft-ietf-sip-session-timer-09.txt, and I meet a question in the draft.

  in Page 9 (7.1 Generating a Session Refresh Request), it mentions:
  "The value of the Min-SE header field present in a session refresh
   request MUST be the largest value amongst all Min-SE header field
   values returned in all 422 responses, or received in session refresh
   requests, on the same dialog, if a dialog has been established. If no
   dialog has been established, the Min-SE header field value is set to
   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~Since the dialog has not been established,
                               then what is "the same Call-ID" mentioned below

   the largest value amongst all Min-SE header field values returned in
   all 422 responses for an INVITE request with the same Call-ID. A
                                           ~~~~~~~~~~~~~~~~~~~~~~
                                            comparing with other dialog's Call-ID?

   result of this rule is that the maximum value of the Min-SE is
   effectively "cleared" once the dialog is established, and from that
   point on, only the values from proxies known to be on the proxy path
   will end up being used."

Thanks a lot to give an answer!

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---

From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 23 Aug 2002 06:02:10 -0400

When the client sends an initial INVITE, it uses a particular call-ID.
If it receives a 422 to that INVITE, it generates a new INVITE with the
same Call-ID. THis new INVITE has a Min-SE header, whose value is the
largest Min-SE returned in all 422 responses to an INVITE with the same
Call-ID. In this case, its the one previous 422, so that Min-SE is used.
If this second INVITE should generate another 422, it tries a third
time, this time with the Min-SE being the maximum of the previous two.

This rule is not clear from the draft. I will clarify.

-Jonathan R.

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