> > I have a question about the 3263 procedures and how they interact > > with DNS servers which round-robin the values in A records. > > 3263 says that the resolution procedures "MUST be done exactly once > > per transaction". My confusion is that this would seem to allow > > the BYE for a dialog to be sent to different peer than the INVITE. > > > > How is this prevented? It is just implied that the > > the FQDN returned > > as a contact is different than the FQDN in the request URI and > > that the former always resolves to only the specific host?
If the reached server wants to ensure it is tried first for subsequent requests within the dialog, it must provide a Contact which reflects such a desire. Contrary to RFC3263, some products do continue to use the reached location if it remains one of the resolved choices within the dialog. This might provide better interoperability, quicker delivery of a request, and work better when SRV is not supported/configured. However this prevents load balancing within a dialog. And it prevents someone trying to retarget the dialog while remaining a lower choice within the dialog. _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
