Suppose a session-timer of 30 minutes duration has been negotiated between two UAs. A session-expires value of 30 minutes was negotiated and UA1 is the refresher. UA1 starts a timer of value 15 minutes and UA2 starts a timer of value 30 minutes minus 10 seconds, as per the recommendations in the spec.
Now 10 minutes after the first INVITE negotiation, UA1 sends a re-INVITE (not a timer refresh) to UA2 in order (to negotiate a codec change, put party on-hold etc.) and added the Session-Expires header with the same value that was previously negotiated (30 minutes). For some reason, the re-INVITE was rejected with some 4xx/5xx response (something other than 408 and 481). What should the UAC do now? What happens to the previously negotiated value of Session-Timer? As per my understanding, if the response to a re-INVITE with a Session-Expires header is not a 2xx with a session_expires header, the session timer is cancelled. Is this correct? If so, what should the UAC do to restore the session-timer? If it is a 488, the UAC can retry with the originally negotiated SDP and succeed. If it is some other error, then what? -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Medhavi Bhatia Sent: Wednesday, July 24, 2002 11:12 PM To: [EMAIL PROTECTED] Subject: Re: [Sip-implementors] SessionTimer behaviour for non-2xx (488) response to re-invite A refresh re-invite (identical in all respects to the original invite) should not receive a 488. You probably mean an actual re-invite which got used as a refresh re-invite. The solution would be to try the old invite to refresh the session again, and if it cannot be refreshed by a 2xx response, it will be terminated by either party. ----- Original Message ----- From: "Sani Tripathy" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Wednesday, July 24, 2002 7:48 PM Subject: [Sip-implementors] SessionTimer behaviour for non-2xx (488) response to re-invite > I have following Session Timer related question: > > >From the following excerpts from section 10 of > draft-ietf-sip-session-timer-09, it seems session timer continues to run > even if a 422 is received. > "Note that only a 2xx response to a session > refresh request extends the session expiration. This means that a UA > could attempt a refresh, and receive a 422 response with a Min-SE > header field that contains a value much larger than the current > session interval. The UA will still need to send an session refresh > request before the session expiration (which has not changed), even > though this request will contain a value of the Session-Expires that > is much larger than the current session interval." > > > Scenario: Received non 2xx response to re-invite > How is the Session Timer managed when a non 2xx response to a refresher > re-invite is received/sent that does not terminate the call? > > In this case the the non 2xx response(e.g 488) does not terminate the call, > the call/session should continue. > > Only a 2xx response extends the session timer, then should a non-2xx > response terminate the session timer and re-negotiate it again. What should > be the actual behaviour? > > > Thanks. > Sani > > > _______________________________________________ > Sip-implementors mailing list > [EMAIL PROTECTED] > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
