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RE: [reSIProcate] reINVITE problem


I haven't seen this problem - but I can understand how it would happen.
To fix this - we need a mechanism to determine if a particular 200
response is a retransmission or not and provide different treatment.
I'll give this some thought.  

Scott

> -----Original Message-----
> From: resiprocate-devel-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:resiprocate-
> devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
> Christian_Gavin@xxxxxxxxxxxx
> Sent: Monday, September 19, 2005 7:13 PM
> To: resiprocate-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [reSIProcate] reINVITE problem
> 
> Hi,
> 
> I am seeing a race condition where a user agent mistakenly receives an
> OnAnswer callback for the wrong sequence (I am using 0.9)
> 
> Here is what is happening (I have skipped the 100 Trying and 180
Ringing
> messages for clarity):
> 
> 1) UA1 ---- INVITE ----> UA2
> (Cseq: 1 INVITE)
> 
> 2) UA1 <----OK with SDP ---- UA2
> (CSeq: 1 INVITE)
> ===> fires an OnAnswer callback, this is correct
> 
> 3) UA1 ------ ACK -----> UA2
> (CSeq: 1 ACK)
> 
> 4) UA1 ---- re INVITE ---> UA2
> (CSeq:2 INVITE)
> 
> 5) UA1 <----OK with SDP ---- UA2
> (CSeq: 1 INVITE)
> (this one is a resend of 2)
> ===> fires an OnAnswer callback, this is incorrect (was already fired
when
> message 2) was received)
> 
> 6) UA1 ------ ACK -----> UA2
> (CSeq: 1 ACK)
> (this is an ACK to message 5)
> 
> 7) UA1 <--- OK with SDP ---- UA2
> (CSeq:2 INVITE)
> ====> this is the response to the second reinvite, doesn't fire an
> OnAnswer
> callback
> 
> 8) UA1 ------ ACK -----> UA2
> (CSeq: 2 ACK)
> 
> When my user agent (UA1) receives the retransmitted message 5), it
thinks
> it is an answer to the reinvite (message 4). However, even if the Call
ID
> is identical, the call sequence is different. Nonetheless the OnAnswer
> callback is fired with the SDP corresponding to the answer to the
first
> INVITE, not the second.
> 
> Has anyone seen this before?
> 
> Thanks,
> Christian
> 
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