[Serusers] rtpproxy question

[Jan Janak]

That will imho not work. If I register my phone behind a NAT with
iptel.org and anyone calls me through a proxy that doesn't force RTP
relay, then iptel.org will not force RTP relay (because there are 2 Via
headers) and I won't hear anything.

 Jan.

On 03-11 19:40, Maxim Sobolev wrote:
> There is another possible solution: modify nathelper to only apply RTP 
> proxy redirection if there is only one Via in the request. This will 
> ensure that in the situation when there are multiple SIP/RTP proxies in 
> the path only first one will handle RTP. Unfortunately it will not help 
> if there are any SIP B2BUAs on the way.
> 
> -Maxim
> 
> Jan Janak wrote:
> >On 03-11 19:18, Maxim Sobolev wrote:
> >
> >>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.
> >
> >
> >  Another option would be to insert a header field telling that another
> >  RTP proxy is being used already.
> >
> >  The problem is that both solutions (header field and SDP flags) will
> >  be not interoperable.
> >
> >  Another option would be to modify the RTP proxy so that it will be
> >  symmetric only for user agents that belong to the domain of the proxy.
> >  That would probably complicate things a bit.
> >
> >    Jan.
> >
> >
> 
>