On Tue, 2009-03-03 at 11:34 +0100, Iñaki Baz Castillo wrote: > 2009/3/3 sarvpriya <[email protected]>: > > hello, > > I am currently implementing RFC 3263. My SIP application only supports UDP. > > I want to know that while sending outgoing requests or responses, if it > > fails then alternate address needs to be tried. Can you please give > > definition of this "fails" > > > 1) it could be transport error ( vat kind of transport error for UDP) > > Yes.
In particular, you could receive an ICMP Port Unreachable message. > > 3) similarly while sending in dialog request say info, if I dnt get reply to > > info, then shud i contact alternate ip addresses? > > No, when you send an in-dialog request the destination is the > remote-target (the other endpoint "Contact" header URI). That URI > contains a definitive location, i.e: > - sip:[email protected] -> UDP 1.2.3.4:5060 > - sip:[email protected]:6666;transport=TCP -> TCP 1.2.3.4:6666 > - sip:[email protected]:5082;transport=UDP -> UDP 1.2.3.4:5082 > > In all these cases there is not (and there cannot be) an alternative > address, since the peer you are speaking with has, usually, just one > contact address. However, Contact and Route URIs can contain host names rather than IP addresses, and a SIP element is required to handle these correctly. (In particular, GRUUs will *always* contain host names.) Many phones handle this situation correctly; ones that do not should be avoided. The addresses in Via headers can also contain host names, although very few phones handle them correctly. This is quite a problem, as it makes it difficult for one SIP proxy to take over for another during a dialog. Dale _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
