Paul As a UAC, If an Update has been sent without SDP to refresh the timer and then another even occurs before the 200 Ok to the Update has been received, that necessitates an Offer-Answer negotiation, can another UPDATE be sent with an SDP or should the request be queued pending the 200 OK to the previous UPDATE?
As a UAS, is it expected to accept an Update with an SDP if there is no other offer pending in either direction, but an Update is pending without SDP, for refreshing the timer. The previous Update wihtout SDP may have been received or sent by the UAS. Now, is it necessary to send a 500 with Retry-After if an Update with SDP is received when a UPDATE without SDP has not been yet sent a final response? Is it necessary to send a 500 with Retry-After if an Update without SDP is received when a UPDATE with SDP has not been yet sent a final response? It seems pointless to send a 500 in the above cases because they do not really pose a conflict. However, the UPDATE draft seems to recommend doing this? I am wondering if the the UPDATE draft should be modified to accomodate the use of UPDATE without SDP? As I see it, first the UPDATE draft was written to support offer-answer and laid down rules assuming UPDATE will always carry a SDP, since it was invented for that purpose. Then Session-Timer draft was modified to allow UPDATE also for refreshing timer. In this draft, two items appeared that is sort of at-odds with the UPDATE spec. One is RECOMMENDING sending UPDATE for refresh and other is without SDP and the other is RECOMMENDING not sending a SDP in that UPDATE. So, these give rise to questions above as well as Sani's questions. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Paul Kyzivat Sent: Wednesday, September 18, 2002 8:08 PM To: Sani Tripathy Cc: Sip-Implementors (E-mail) Subject: Re: [Sip-implementors] Processing Update without SDP when an Update is pending Sani, I don't think this is legal. But it also shouldn't be necessary. An UPDATE without SDP is a good way to update the session timer if that is all you need to do. But if you are sending an UPDATE for some reason you should take the opportunity to use it to refresh the session timer as well. I posted a similar question about this some time ago but using reINVITE. There was a response from Brett Tate, but no other discussion that I recall. As I read the spec, I believe that an UPDATE or reINVITE that doesn't mention the session timer actually causes the session timer to be cancelled, leaving the session without a timer. But the language is sufficiently obscure that it would be good to get a clarification. Brett agreed wrt reINVITE. I have attached the older messages. Paul > Sani Tripathy wrote: > > My question is : Is it possible to send Update without any offer when a re-invite or Update having an offer is pending? > > According to Session-Timer -- draft-ietf-sip-session-timer-09.txt, Update is recommended to be used as the refresher request instead of a re-invite. It is recommended that Update used for refresh should not have SDP. > > Update draft suggests that > "if the UPDATE is being sent after the completion of the initial INVITE transaction, > it cannot be sent if the caller has generated or received offers in a re-INVITE or > UPDATE which have not been answered. " > This is justified when Update is used only for offer-answer purpose, but can be overridden while being used for session timer. > > Thanks, > Sani > > > > _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
