Iñaki, Just wanted to confirm about the use case you defined! In either case where Bob accept or deny the new SDP offer in Re-INVITE, where the use case exists for CANCEL?
Best Regards, Vivek Batra -----Original Message----- From: sip-implementors-boun...@lists.cs.columbia.edu [mailto:sip-implementors-boun...@lists.cs.columbia.edu] On Behalf Of Iñaki Baz Castillo Sent: Wednesday, November 11, 2009 5:55 PM To: MUTHU VEERAPPAN ALAGAPPAN Cc: sip-implementors@lists.cs.columbia.edu Subject: Re: [Sip-implementors] Re-Invite Cancel Possible ? 2009/11/11 MUTHU VEERAPPAN ALAGAPPAN <alagappan.muthu_veerap...@alcatel-lucent.com>: > Is it valid to send a cancel for re-invite? Yes. > Can anyone tell me the usecase of a re-invite cancel? Alice has a voice session esablished with Bob. Alice wants to add video to the session so its phone sends a re-INVITE adding video capabilities. Bob phone asks the user to allow/deny the new offer. Bob press "Accept" buttom so video is added to the session. > I understand that when we have a proxy b/w the UAC and UAS, all SIP > Messages flow end to end, except for the CANCEL message which is > hop-by-hop. > > > > In this context for the following scenario please tell me what can be > done. > > > > * After a call is established with a UAC, Proxy and UAS. > * When we receive a re-invite from UAC > * Proxy forwards this to UAS. > * UAS responds with 1xx response. > * Proxy forwards this to UAC. > * UAC sends CANCEL for this re-invite > * At the same time if the UAS responds with a 200 OK. > > > > > > What should a proxy do in the above race condition scenario? There are some RFC's or drafts about this issue (race conditions), cannot remember them right now. But it's the same as in the case of the initial INVITE. > > * Can proxy ACK the 200 OK from UAS? But for the UAS side it > will mean that the re-invite is done? Will it create problems? > * Should the proxy send a bye to the UAS? But this will end the > dialog rite? A proxy doesn't generate transactions by itself (ACK for a 200 or a BYE). No, it shouldn't. -- Iñaki Baz Castillo <i...@aliax.net> _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors Email Scanned for Virus & Dangerous Content by : www.CleanMailGateway.com _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
