[Serusers] nat + multiple RTP proxy
Klaus Darilion
darilion at ict.tuwien.ac.at
Fri Dec 12 18:42:54 CET 2003
The problem was already discussed in
http://lists.iptel.org/pipermail/serusers/2003-November/003461.html
and the suggested solution was the same as your solution.
Klaus
> -----Original Message-----
> From: dhiraj.2.bhuyan at bt.com [mailto:dhiraj.2.bhuyan at bt.com]
> Sent: Friday, December 12, 2003 6:39 PM
> To: jiri at iptel.org; sobomax at portaone.com
> Cc: serusers at lists.iptel.org
> Subject: [Serusers] nat + multiple RTP proxy
>
>
> Greetings list,
> I spent some time looking into the rtpproxy and nathelper
> code. Currently, nathelper + rtpproxy will work ONLY if there
> is "one" RTP proxy on the path. In a scenario like -
>
> UA1 ---- NAT ---- SER/RTP1 ----- SER/RTP2 ---- NAT --- UA2
>
> where UA1 and UA2 are subscribed to two different SERs and
> are also behind NAT, RTP proxy 1 never forwards the RTP
> traffic from UA1 to RTP proxy 2 (because of the way it is
> designed) since RTP1 is waiting for at least one RTP packet
> from RTP proxy 2 and vice versa - hence the deadlock.
>
> This can be fixed if the RTP proxy waits for one UDP packet
> from the device behind NAT, but does not wait for any packets
> from the device it thinks is not behind NAT before forwarding
> it the RTP traffic (coming from the other end). Thus in the
> above scenario, RTP 1 waits for at least one packet from UA1
> - but does not wait for any packet from RTP2.
>
> I am writing a patch for nathelper and rtpproxy to add this
> functionality (should be available by next week). Anyone -
> any thoughts on this?
>
> Dhiraj Bhuyan
> Network Security Specialist,
> BT Exact Business Assurance Solutions
>
> Tel: +44 1473 643932
> Mob: +44 7962 012145
> Email: dhiraj.2.bhuyan at bt.com
>
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