On Sat, 2009-03-21 at 11:28 -0400, Jonathan Rosenberg wrote: > Now B and C are talking to each other. What is the session ID for this > dialog? B and C were both originally the UAS on different dialogs with > different session IDs!
The essential problem (which also shows up in draft-loreto-sipping-context-id-requirements) is that you need to express a correlation between two dialogs, but the correlation is discovered after both of the dialogs have been initiated. If I may be immodest, the References header could a solution: State that two dialogs are related to each other by (effectively) naming both call-id's together, rather than by assigning them a common identifier when they are created. In regard to correlating the two legs of a call through an SBC, see section 5.2 of draft-worley-references-02. The SBC can put a References header in a message going out on one leg that contains the call-id of the dialog on the other leg, or vice-versa. If the SBC wants to be paranoid, it can create a pseudo-random pseudo-Call-Id and put it in a References header in two messages, one going out each leg. That's not elegant, but it's effective and safe -- and doesn't depend on the UAs. As far as I can tell, the References header handles all of the use cases people have stated. Dale _______________________________________________ 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
