[Sip] some comments on draft-ietf-sip-session-timer-09.txt

[hbhondwe@hss.hns.com]

Hi,

some questions and comments on draft-ietf-sip-session-timer-09.txt. Pardon
me if these have already been discussed before.

1.Why is it that only a session refresh request or its 2xx response
supposed to refresh the session?(See section 10. Performing Refreshes)
For example consider the following scenario:
UAC                                                             UAS
                session is established
                with UAS as the refresher
(session timer active)                          (session timer active)


(UAC wishes to change some parameters of the session)
(UAC sends an re-INVITE)
 --------INV---------------------------------------->
                                                                    (Should
UAS not reset its session timer on receiving it?)
<-------200 Ok-----------------------------------
(Should UAC also not reset its session timer on receiving 200 OK?)


2.Section 8.1 Processing of Requests says
"If the request contains a Supported header field with a value
   "timer", the proxy MAY reject the INVITE request with a 422 (Session
   Interval Too Small) response if the session interval in the Session-
   Expires header field is smaller than the minimum interval defined by
   the proxy's local policy. When sending the 422 response, the proxy
   MUST include a Min-SE header field with the value of its minimum
   interval.".

Apart from this option, does the draft allow the proxy to  increase its
local minimum interval?.
Can the proxy also forward the request?
Can it discard the request, send no response back?if the proxy does not
respond back with a 422,
the requestor/refresher will not know what value to use for the session
timer in its retry.
The draft does not specify what (other) actions can the proxy take in this
case.
If there are no other possible useful actions for the proxy, then should
not  the MAY be changed to SHOULD?

regards
harsh







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