Subject: [Sip] one last update to session timer...

From: Jonathan Rosenberg <[email-masked]>
Date: Sat, 6 Oct 2001 16:49:43 -0400

Folks,

It was my expectation that draft-ietf-sip-session-timer-07.txt would go to
IESG. However, I received a very late private email pointing out a problem
in the spec.

The problem was this. UAC sends an INVITE with Supported: timer. This goes
through some proxies and a UAS, and the result is a Session-Expires in a 200
OKwith a really low value; lower than what the UAC would like. However,
since its a 200 OK, a session has been established with that interval. The
spec says nothing about how a UAC handles this case; it works fine based on
the spec only if the interval is too low for a proxy. In the case of a
proxy, the next refresh would have the low session-expires, and would then
be rejected by the proxy with a 422, containing a Min-SE with the minimum
value. In the case of a UAC, all we need to do is specify that it can
increase the value of Min-SE in a refresh. I added a few sentences to that
regard.

I also moved a few paragraphs around in the section on UAC behavior, just
for clarity.

draft-ietf-sip-session-timer-08.txt was submitted to the archives today, and
should appear shortly (and then head to IESG). Until then, you can pick up a
copy at:

http://www.jdrosen.net/papers/draft-ietf-sip-session-timer-08.txt

-Jonathan R.
---
Jonathan D. Rosenberg, Ph.D.                72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.jdrosen.net                      PHONE: (973) 952-5000
http://www.dynamicsoft.com

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