> > Sending 199 is useless overhead unless something > > along the path supports and wants it. > > Correct. But useless can still be harmless :) > > Personally I don't care what we do - I simply > indicated what seemed to be the agreement at the meeting.
The "harmless" uselessness would likely depend upon the frequency of 199 versus the extra option-tag or header to negotiate the mechanism. I don't have a strong opinion about the need for negotiating the mechanism. I'm just trying to avoid some unnecessary interop issues and capacity hits. > > If UAC does not support 199, sending it might > > cause more harm than good. > > A UAC should discard what it doesn't support. RFC 3261 section 8.1.3.2: "A UAC MUST treat any provisional response different than 100 that it does not recognize as 183 (Session Progress)." The above requirement adds complication for devices (not supporting 199) only maintaining a limited number of early dialogs or using latest 1xx to recognize most likely active early dialog. The 199 could trigger them to forgot or not prefer a useful early dialog for the one associated with 199. > > If no proxy steals another's To tag for originating > > a final INVITE response, I agree. I don't recall > > what rfc3261 and invfix recommend concerning the > > abnormal situation from proxy and UAC perspectives. > > I was mainly just asking for conceptual reasons > > based upon the paragraph prior to my question. > > If it occurs, should the originator of 199 tag X > > process the 2xx tag X like a UAC or proxy? > <snip> > Maybe it could steal a tag when sending an error > response, but in that case I guess it doesn't > matter very much. I guess the UAC could simply ACK it. Yes, my question was mainly concerning situation caused by proxies that incorrectly use another's early dialog To tag when originating a failure INVITE response like 487 when no final INVITE response has been received. Hopefully there are no longer proxies that actually do it. :) If the 199 originator uses such a tag to send 199 and INVITE 200 received using the same tag, I was curious how the 199 originator should behave (as proxy or UAC). If it proxies the INVITE 200, the call might actually get established and stay up when UAC does not support 199 or 199 was dropped. _______________________________________________ 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
