[OpenSIPS-Users] parallel forking and CANCEL/BYE

Bogdan-Andrei Iancu bogdan at voice-system.ro
Tue Oct 20 18:33:13 CEST 2009


Hi Uwe,

So actually both legs do send 200 OK (but one faster than the 
other)......so there is kind on race between the 200 OK from the slow 
branch and the CANCEL from OpenSIPS...is this the case?

If so, the UAS will simply reply with negative reply to CANCEL (decline 
it) and opensips (for INVITE transaction) will not close the second 
branch as there is a 200 OK (and not a 487) received ....RFC3261 says 
that a proxy must send all 200 OK (for a call), even if more than one, 
to the UAC - the UAC is the one who will decide what branch to keep and 
it will fire a BYE for the other branch.

Regards,
Bogdan

Uwe Kastens wrote:
> Hello again,
>
> I was wondering if there might be a bug with the correct handling of
> Cancel in case of receiving and final answer.
>
> I will fork one Call to 2 nodes. One node answers a little faster than
> the other and will get the call. Opensips will send a CANCEL for the
> other node which is sending a SIP/2.0 200 OK before receiving the
> CANCEL. So this node is not answering with a 487 but with a 200/OK.
>
> Opensips seems to drop the call leg and so the BYE from that node could
> not be handled.
>
> Is this behaviour RFC conform?
>
> I will attach one ngrep and one opensips logfile
>
> BR
>
> Uwe
>
>
>
>
> Uwe Kastens schrieb:
>   
>> Hi,
>>
>> I am using opensips to fork calls to UAs which are registrered from 
>> different IPs/Ports.
>>
>> If one UA accepts the INVITE the other UAs will get a CANCEL.
>>
>> Now I have one subscriber with 2 asterisk server which asked me to send 
>> a BYE after the CANCEL. Otherwise he wants me to send an BYE which could 
>> not be processed correctly on the opensips.
>>
>> I am pretty sure, that this kind of handling would not be RFC conform 
>> and so its not possible to handle this inside the routing script. Or did 
>> I missed something?
>>
>> BR
>>
>> Uwe
>>
>>
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>>     
>
>
>   
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