21 Aug
2007
21 Aug
'07
5:20 p.m.
Valentin -
The NAT uses one port to transmit to the outside world and receiveds on
an other port during the call. This NAT (Linux router/gateway for the
end point like an ATA or softphone) is at customer location. I gather
from the customer that the the end point (client behind NAT) is
symmetric w.r.t its RTP port (same port for tx and rx of the RTP stream).
The signaling IP and RTP IP are not the same.
I am newbie to
this field. We are trying to use a separate card for
handling the rtp voice traffic but use the RTPProxy (IPtel) software to
handle the NAT issues. We have been fairly successful in doing that.
The problem now is to handle asymmetric NATs. I hear one way audio.
What do you mean as "asymmmetric NAT"?
Cone NAT or asymmetric RTP client behind NAT?
We are not
sure how to handle this when there is one machine running
rtpproxy software and another card with a different IP handling the SDP
(In nathelper.c of Openser new_ip= card IP). In the symmetric NAT
scenario this works fine. I would appreciate and pointers to modify
rtpproxy for this configuration.
So I suppose you mean asymmetric client behind NAT, don't you?
It's more hard case. But if only signaling IP and IP for RTP
differs, it's good. Problems (almost unavoidable) appear if
client's source RTP address differs from destination RTP address
(specified in SDP), "address" here means both host and port.
The destination IP of the RTP channel opened in the card which works in
conjunction with rtpproxy is the IP of the NAT router/gateway and source
IP of the RTP stream coming into this card handling RTP stream is also
that of the same router/gateway. But the ports are different. Do you
think this is the problem?
Please note-
We use rtpproxy 0.3, Opneser 1.1.0.
-the card only handles RTP data and has its
own GbE port
- made changes to nathelper.c nathelper.cfg
source code to account for separate IP addrs
- made changes to RTPProxy to open channels for RTPtraffic flow on the
card.
-Openser,RTPProxy and the card , all 3 different Public IPs
Thank you for the response.
Regards
Nithin