[OpenSIPS-Users] Parallel forking (using registrar branching) & mediaproxy

Ruud Klaver ruud at ag-projects.com
Mon Jun 8 16:33:09 CEST 2009

Hi Erwan,

On 04 Jun 2009, at 12:09, erwan.humez at orange-ftgroup.com wrote:

> Hi,
> I came across something weird about parallel forking: media  
> information (IP @ received from SDP for RTP) is not properly  
> communicated to media proxy, but only for one of the 2 calls.
> Here is the context :
> opensips 1.5.1 / mediaproxy 2.3.4 / Centos 5.2, on IP
> Caller on sip softphone, on IP
> Called on 2 tdm cisco media gateways, each registered using the same  
> uri 8003 at behind 2 different IP@ : and
> Objective is to achieve a call // forked from sip to both tdm called  
> parties.
> // sip forking seems to be working fine in the way that when one  
> picks up the other one is properly cancelled. For information, both  
> media gateways send a 183/SDP message and then a 200 OK/SDP upon  
> pick-up. Media proxy sends/forwards 183/SDP messages to caller  
> without modifying IP @ (keeping & and then only  
> sends the modified (with media proxy IP@) 200 OK/SDP message to the  
> caller upon pick-up.
> The issue (check below for media proxy traces) is reproductible  
> because each time the same gateway is impacted (no need to precise  
> that basic calls are working fine in both ways for call setup and on  
> both gateways, which should prevent from any network related issue/ 
> question).
> Of course i got all required traces that i can provide upon request  
> to avoid spamming the list but so far and mainly, here is what i can  
> see from media proxy traces:
> Working call:
> debug: Got traffic information for stream: (audio)  
> (RTP:, RTCP:  
> <-> <->  
> <-> (RTP:, RTCP:
> => RTCP IP is not correct here but does not prevent the call to be  
> successfully established.
> Non-working call:
> debug: Got traffic information for stream: (audio)  
> (RTP:, RTCP:  
> <-> <->  
> <-> (RTP:, RTCP:
> => RTP information is taken from the 183/SDP message  
> sent by the gateway to wich the forked call is canceled: it should  
> be the RTP information coming from the 183/SDP message sent by the  
> other gateway (
> => neither RTP and RTCP are correct here. Network traces confirm  
> that media proxy keeps sending RTP packets towards  
> getting an icmp destination port unreachable of course.
> I understand that SDP information received in both 183 messages  
> could cause some troubles in opensips and media proxy  
> communications... Somewhere and somehow, the information should be  
> updated in media proxy...
> ... but maybe i missed or misunderstood something, so please can  
> someone enlight me on this issue ?
> Thanks a lot for help and support,
> Erwan.

I don't think I fully understand your scenario and what exactly is  
happening here. One issue could be that MediaProxy was never designed  
to operate using a private IP address. Could you please provide be  
with full logs from both the relay and the dispatcher?

Ruud Klaver
AG Projects

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