Bob Penfield wrote: > >> -----Original Message----- >> From: Paul Kyzivat [mailto:[EMAIL PROTECTED] >> Sent: Tuesday, June 17, 2008 11:44 PM >> To: Bob Penfield >> Cc: [email protected] >> Subject: Re: [Sip] I-D ACTION:draft-ietf-sip-199-00.txt >> >> >> Bob Penfield wrote: >> >>> On the topic of UAS's sending 199, I actually think things will work >>> better if they did. I know there has been lots of discussion about >>> B2BUAs doing it, but consider a UAS that is aware that it has multiple >>> registered contacts (via presence or registration event package or >>> other means), it might want to send the 199 to be sure that it does >>> reach the UAC (in case the proxy does not support it). >> Bob, I don't understand the point you are making. Can you explain further? >> >> Are you talking about a case where there is a forking proxy in front of >> the UAS, and the proxy doesn't know about 199, and the UAS wants to send >> the 199 to give the UAC a warning in case the final response is delayed >> by the proxy? > > Yes, that is pretty much the case I was considering. > >> While there may be some cases where that would be advantageous, in many >> others it would just increase the message traffic for every failing >> call. And I don't see how the UAS would be able to discern the cases >> where it would be advantageous. I guess it could be configured in those >> cases where all inbound calls are forked, but how many such cases are there? >> > > If the UAS knows that the AOR has multiple registered contacts, it knows that > inbound calls will be forked. In that case, it could send the 199. As long as > proxies don't generate 199s in addition to ones they forward, the increased > traffic could be limited.
How often does a UAS know that there are multiple contacts for this AOR? Even if it does, it presumably can't know if it is the last one tried, the first, or whatever. > Having proxies generate responses on behalf of a UAS is a bit of a violation > of the end-to-end principle from a purist point of view. By certainly having > only proxies generate 199s would limit the increase in messages. Yes, it is. > I was just trying to point out that there might be cases where real User > Agent would send 199 and not just B2BUAs. I do appreciate the point that there *can* be cases where the UAS would have enough info to justify sending a 199 response. But the cases where a UAS is likely to know that in practice seem limited, with the exception of B2BUAs. I would just like to avoid giving UA developers the idea that they *ought* to be generating 199 responses on a regular basis. Doing so "to be helpful" is likely to be sub-optimal in many cases. >> Paul >> > _______________________________________________ > Sip mailing list https://www.ietf.org/mailman/listinfo/sip > This list is for NEW development of the core SIP Protocol > Use [EMAIL PROTECTED] for questions on current sip > Use [EMAIL PROTECTED] for new developments on the application of sip > _______________________________________________ Sip mailing list https://www.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use [EMAIL PROTECTED] for questions on current sip Use [EMAIL PROTECTED] for new developments on the application of sip
