[asterisk-users] SDP bug

Olle E Johansson oej at edvina.net
Mon Apr 2 23:20:00 MST 2007

2 apr 2007 kl. 19.32 skrev Raj Jain:

> I found a subtle difference between the two traces you sent (the  
> call that works and the call that gets dropped). This may or may  
> not be what's causing the problem.
> The call that gets dropped had a retransmission of INVITE from UAC  
> to UAS (and therefore retransmission of 200 OK from UAS to UAC).  
> There is nothing wrong with the re-transmission as such, but I  
> noticed a potential bug in Asterisk in the way it responds to an  
> INVITE retransmission. Asterisk is bumping up the session version  
> number in the retransmitted 200 OK's SDP. This is as if Asterisk is  
> treating the INVITE retransmission as a RE-INVITE.
> Asterisk sends 200 OK:
> o=root 16300 16300 IN IP4 203.89.nnn.nnn
> Asterisk sends 200 OK (retransmission):
> o=root 16300 16301 IN IP4 203.89.nnn.nnn
> Ideally, this bug should have nothing to do with why Asterisk is  
> ignoring the ACK (which is why it keeps reatrasmitting the 200 OK  
> and eventually drops the call). However, if you can confirm that  
> all dropped calls have INVITE retransmission then that might give  
> us a clue?

That's an interesting observation. Do you think this will cause any  
issues? Even though it's not
beautiful, I fail to see why a UA would check that.


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