> -----Original Message----- > From: Jiri Kuthan [mailto:[EMAIL PROTECTED] > Sent: 17 November 2008 13:20 > To: Hadriel Kaplan > Cc: Dan Wing; 'Adam Roach'; [EMAIL PROTECTED]; 'SIP > IETF'; [EMAIL PROTECTED]; Elwell, John; > [EMAIL PROTECTED]; [EMAIL PROTECTED] > Subject: Re: [Sip] draft-kuthan-sip-derive > > Hadriel Kaplan wrote: > > > >> -----Original Message----- > >> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > On Behalf Of Jiri > >> Kuthan > >> Sent: Sunday, November 16, 2008 5:54 PM > >> To: Dan Wing > >> > >> Aside from architectural and evolution arguments on both a > and b, does > >> anyone > >> have an opinion on what can safely get through the B2BUAs? > > > > Audio. :) > > Whatever you choose, don't use the call-id or tags. > > :) > > well, this is really guessing which can be quite brittle but > isn't dialog > id safer? For lot of other things to function, it must be translated > consistently from A to X on one side and X to A in the > reverse direction, > mustn't it? So that using some method with same callid/tags > as the tested > INVITE should get to the same place? [JRE] It requires the B2BUA to modify the contents of the SUBSCRIBE and NOTIFY bodies. If B2BUAs would do this, that would work. The problem I see is that a non-compliant B2BUA might act as UAS for the SUBSCRIBE request and send back a NOTIFY with its own dialog information. It only proves that the call has come from that B2BUA, which doesn't mean much. How does the callee UA distinguish this unhelpful case from the helpful case where the SUBSCRIBE request has been relayed all the way back to the caller's UA (or at least the caller's domain) and the NOTIFY comes from there? I guess it falls back to using RFC 4474 to sign the NOTIFY request. But then a NOTIFY request signed by the local domain's B2BUA is unhelpful, and a NOTIFY request from the caller's UA or its domain proxy/B2BUA would have its signature broken by intervening B2BUAs. So we are back where we started.
I suppose we have two seemingly incompatible requirements: - it must work through any "reasonable" B2BUA behaviour in such a way that the callee UA can detect whether e2e return routability has been achieved; - it must work without modifications to existing caller UAs. If it is indeed impossible to satisfy both requirements, then which of these is more important? John _______________________________________________ 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
