> -----Original Message----- > From: Paul Kyzivat [mailto:[EMAIL PROTECTED] > Sent: Friday, October 19, 2007 5:35 PM > To: Christer Holmberg > Cc: Stucker, Brian (RICH1:AR00); sip; Adam Roach; Michael > Procter; Elwell,John > Subject: Re: [Sip] INFO > > > > Christer Holmberg wrote: > > Hi, > > > > One potential issue: the stateful intermediate receives a > NOTIFY without any previous SUBSCRIBE. Is there a chance it > would act on this, e.g. by sending a 4xx response, or are we > sure it would always simply forward the NOTIFY and assume the > endpoint will handle it? > > Are you talking about a B2BUA or a proxy? > > If a B2BUA, it suffers the common problem that it needs to be > aware of pretty much all the standards in use by those it is > connecting.
No it doesn't. A B2BUA does not need to understand a great many things. One thing it does need to understand is how all of the fundamental SIP methods interact with one another. A B2BUA could be doing anything or nothing, but it always has to know when and how dialogs/usages are created, maintained and destroyed. That's the minimum requirement. > > If it was not aware of this new extension, and it was trying > to enforce rules about what messages are allowed in what > contexts, then yes it might cause trouble. But we specify > stuff all the time that has similar issues with B2BUAs. Its > up to B2BUAs to figure out how to be transparent or else go away. Nice thought, but they aren't going to go away. It is currently the case, and going to continue to be the case, that a great deal of the SIP endpoints in this world will only be addressable with a B2BUA in the path for a wide variety of possible reasons. Before you flame me, go ask your system engineers how many SIP endpoints they've personally seen commercially deployed that were addressable via the Internet that were not protected by some sort of ALG or B2BUA scheme that you'd be willing to post the address of their SIP proxy and the usernames of several account holders there. There may be a few, but they're pretty rare, and that's why it matters. It'd be a shame that, by not acknowledging this simple fact, that we wind up building our own walled garden. We need to make things work the best we can in the environment we're given, not the one we wish we had. Regards, Brian _______________________________________________ Sip mailing list https://www1.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
