[Serusers] rtpproxy question

[Maxim Sobolev]

Klaus Darilion wrote:

>Hi!
>
>As the RTP relaying does not work with 2 RTP proxies, how can a proxy detect
>if the RTP stream is already redirected to an RTP proxy?
>
>My problem is the following scenario:
>
>UA1   --NAT--   SIP proxy 1   --   SIP proxy 2   --NAT--   UA2
>                 rtpproxy1          rtpproxy2
>
>UA1 invites UA2. SIP proxy 1 detects that UA1 is behind NAT and enables the
>rtpproxy1 and forwards the invite to SIP proxy2. SIP proxy 2 knows that UA2
>is also behind NAT. Usually, SIP proxy 2 would activate the rtpproxy2, but
>in this case this would not work as there is already an rtpproxy involved.
>How can the SIP proxy 2 detect that the IP address in the SDP is the IP
>address of an RTP proxy?
>  
>
Known problem. I think that I'll modify nathelper, so that 
force_rtp_proxy() will insert some flag into the SDP body, which will 
tell other proxies along the request route that there is no need to put 
another RTP relay into the RTP path.

Regards,

Maxim