[SR-Users] Cancel rtp proxy changes to SDP

[Alex Balashov]

David,

On 07/01/2010 09:19 PM, David wrote:

> Hello,
>
> I have setup an application level gateway that bridges my two networks.
> I have a situation where an INVITE will cross the gateway ( thus
> rewriting the SDP ) go through a proxy and come back across the gateway.
>
> At this point, it would be wasteful to use the RTP Proxy as the audio
> will be between two devices on the same network.
>
> Is there a command I can execute as the INVITE comes back to cancel the
> changes made by RTP Proxy ?

What precisely do you mean when you say "come back across the 
gateway?"  Are you referring to a spiral, i.e.

    INVITE (source) --> proxy (+ rtpproxy) --> proxy --> proxy (+ 
rtpproxy)

If so, why would the second situation be topologically different 
relative to the first situation?  And why is the call flow like that?

Either way, you can embed the old SDP into the INVITE as a custom 
header (append_hf() from textops) and then run fix_nated_sdp() with 
arguments extracted from that custom header to revert the changes.

But this requirement seems strange to me;  perhaps there is a better 
way to do it?

-- 
Alex Balashov - Principal
Evariste Systems LLC
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