[SR-Users] How to Fix the RTP Engine SDP Rewriting direction.

[Richard Fuchs]

On 12/16/14 10:04, Mahmoud Ramadan Ali wrote:
> Hi Dears,
> I'm working on integrating the rtpengine to work with Kamailio as RTP
> proxy and i have successfully configured the rtpengine in multi home
> mode to proxy the media and rewrite the SDP message whenever it passes
> trough the Kamailio internal interface to the external interface and
> vice versa using this command.
> 
> root at debian:/usr/local/etc/kamailio# rtpengine
> --interface=Kamailio-Internal/192.168.100.1 <http://192.168.100.1>
> --interface=Kamailio-External/192.168.50.1 <http://192.168.50.1>
> --listen-ng=127.0.0.1:22222 <http://127.0.0.1:22222>
> --pidfile=/var/run/ngcp-rtpengine-daemon.pid
> 
> Also i have configured the "i" and "e" flags in the route[NATMANAGE] to
> take care of the SDP rewriting direction the same way it worked before
> with my rtpproxy module configuration.
> 
> But the issue now is that whenever i make a call from the external to
> the internal the rtpengine can NOT detect the right direction as colored
> in red below so my question now is : How to set the direction of the
> rtpengine to designate that the interface 192.168.50.1 is the external
> and 192.168.100.1 is the internal ?
> 
> Dec 16 09:28:09 debian rtpengine[4714]: Got valid command from
> 127.0.0.1:50639 <http://127.0.0.1:50639>: offer - { "sdp":
> "v=0#015#012o=- 13063213690566395 1 IN IP4 192.168.50.2#015#012s=X-Lite
> release 4.7.1 stamp 74247#015#012c=IN IP4 192.168.50.2#015#012t=0
> 0#015#012m=audio 56078 RTP/AVP 125 100 0 9 8 101#015#012a=rtpmap:125
> opus/48000/2#015#012a=fmtp:125 useinbandfec=1#015#012a=rtpmap:100
> speex/16000#015#012a=rtpmap:101 telephone-event/8000#015#012a=fmtp:101
> 0-15#015#012a=sendrecv#015#012", "direction": [ "internal", "external"
> ], "flags": [ "asymmetric", "trust-address", "symmetric" ], "replace": [
> "session-connection", "orig ...

If you want to use the "i" and "e" flags, you must name your logical
interfaces "internal" and "external" respectively, as in:

./rtpengine ... --interface=internal/192.168.100.1
--interface=external/192.168.50.1 ...

Alternatively if you wish to retain and use the more free-form interface
names, you must use the "direction=..." option in your calls to
rtpengine_*(), but you'd need a more recent version of the rtpengine
module for this to work.

cheers