[reSIProcate] Forked INVITEs

[Robert Sparks]

Chris -

The call flow you're seeing (through the INVITEs and CANCELs anyhow)  
is correct.

When a proxy forks it is only going to forward one final response  
(when that response
is non-2xx) to an INVITE. It's possible to get more than one 2xx, but  
that's an edge case
that is made as unlikely as possible by the rules in section 16 of  
3261. You will never
see both a 2xx final response and some other non-2xx final response.

Now, for the BYE question. The protocol is doing the right thing  
given that a BYE was
sent, but sending the BYE was (probably) silly. Are you using DUM or  
the stack directly
for this flow? Were the 180s using the 100rel extension?

RjS

On Jan 16, 2006, at 11:49 AM, Christian_Gavin at logitech.com wrote:

> Hi,
>
> I am testing the following scenario with resip 0.9 on WinXP. Server  
> is SER
> 0.9 on Solaris.
>
> One client is registered as sip:chris at server.com (server.com is a
> placeholder for the SIP server I am using). Let's call this client A.
>
> Two other clients are registered as sip:chris2 at server.com (let's  
> call these
> client B and client C). Client A calls B and C and then cancels the  
> INVITE:
>
> - chris INVITEs chris2
>
> - both clients registered under chris2 (client B and C) ring, send 180
> Ringing to server which is turn sends both 180 Ringing to chris
>
> - chris cancels the INVITE
>
> - chris receives a 200 Canceling from the server
>
>       - clients B and C receive a Cancel
>
>       - B and C send a 200 OK in response to the Cancel and a 487  
> Request
> Terminated to the server
>
>       - the server sends ACKs to B and C
>
> - chris receives a 487 Request Terminated from the server (with  
> same To:
> and From: tags as specified in the first 180 Ringing coming from  
> client B)
>
> - chris ACKs the 487 Request Terminated
>
> At this time, B and C are done with canceling. However, chris  
> (client A)
> has only received one 487 Request Terminated from the server,  
> corresponding
> to the call leg A <-> B. Client A thinks the extra call leg created by
> forking (A <-> C) still exists, and 20 seconds later, reSIProcate  
> on client
> A sends a BYE to client C to terminated this call leg. Client C  
> replies
> with a 481 Call / Transaction Does Not Exist.
>
> Shouldn't reSIProcate automatically close all call legs once the  
> initial
> INVITE has been canceled? Or should the server send an extra 487 to  
> chris
> to indicate that this second call leg was terminated?
>
> Thanks,
> Christian
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