[asterisk-dev] udptl ports

Joshua Colp jcolp at digium.com
Sun Sep 14 11:02:48 CDT 2014


James Cloos wrote:
>>>>>> "JC" == Joshua Colp<jcolp at digium.com>  writes:
>
>>> In a report which I received, ast 1.8 used the same port which it had
>>> been using to originate rtp also to originate the udptl.  (The other
>>> side used and advertised the same port in the re-INVITE negotiation
>>> which it had used and advertised in the initial INVITE.)
>
> JC>  Asterisk won't send from the same port. They are two different
> JC>  ranges. If it went through a NAT, though, then the external mapping
> JC>  COULD reuse the port depending on how it operates.
>
> The asterisk in the pcap is not in a nat.  And it certainly did use the
> same src port for the t38 as it had been using for the rtp.  The dst
> ports were different -- each was correctly sent to the other side's
> advertised port -- but both came from the same src.

Unless stuff has been modified or something in between is doing things 
the code just won't allow it. The UDPTL and RTP stacks don't share 
sockets and the RTP side keeps the port open while UDPTL is going on so 
even if the UDPTL side wanted to use the same port it couldn't bind to it.

Can you provide the trace of this with SDP and logging?

-- 
Joshua Colp
Digium, Inc. | Senior Software Developer
445 Jan Davis Drive NW - Huntsville, AL 35806 - US
Check us out at: www.digium.com & www.asterisk.org



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