[Serusers] Proxy Behaviour on a parallel fork

Klaus Darilion klaus.mailinglists at pernau.at
Thu Sep 29 23:17:36 CEST 2005



jim.pafford at comcast.net wrote:
> In ser 0.9.3 I am seeing the following problem with a parallel forking 
> scenario. The SER is sending the final Request ACK to the wrong location 
> every time. Is there a way to fix this.  See below:
>  
> Endpoint (xyz at 1.1.1.1 <mailto:xyz at 1.1.1.1>) sends 
> Invite(abc123 at proxy.com <mailto:abc123 at proxy.com>) to the SER.
> SER looks up location and then sends the following three messages:
> TRYING back to (xyz at 1.1.1.1 <mailto:xyz at 1.1.1.1>)
> INVITE to abc123 at 2.2.2.2 <mailto:abc123 at 2.2.2.2>
> INVITE to abc123 at 3.3.3.3 <mailto:abc123 at 3.3.3.3>
>  
> This looks good so far.
> SER then gets back ringing from both endpoints and sends along to 
> xyz at 1.1.1.1 <mailto:xyz at 1.1.1.1>
>  
> abc123 at 3.3.3.3 <mailto:abc123 at 3.3.3.3> answers the call and sends back OK
> SER then sends OK to xyz at 1.1.1.1 <mailto:xyz at 1.1.1.1> - Still good
> SER then sends CANCEL to abc123 at 2.2.2.2 <mailto:abc123 at 2.2.2.2>
> abc123 at 2.2.2.2 <mailto:abc123 at 2.2.2.2> responds with 200 Canceling - so 
> far so good.
>  
> Now xyz at 1.1.1.1 <mailto:xyz at 1.1.1.1> sends the ACK to (abc123 at proxy.com 
> <mailto:abc123 at proxy.com>) - Still looks good.
>  
> But now after looking up location for abc123 SER sends the ACK to the

Do you use lookup(location) for ACK? This is not necessary. It should be 
handled in loose_route section.

klaus


> wrong endpoint abc123 at 2.2.2.2 <mailto:abc123 at 2.2.2.2>
>  
> What am I doing wrong? SER always sends the ACK back to the first 
> address in the list as shown by serctl ul show abc123.  Is there a way 
> to correct this so that SER knows the correct endpoint to relay the ACK 
> to? Seems like it should understand which endpoint sent back the OK to 
> the original INVITE and then send the ACK to that endpoint and not the 
> first one in the list after a location lookup.
>  
> thanks,
> Jim
> 
> 
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