[OpenSIPS-Users] ACK looping behind NAT

[Sreeram Narayanan]

Hello,

I am trying to use OpenSIPs with the load_balancer module to balance
inbound calls between 2 Asterisk servers. The setup sits behind a NAT. The
OpenSIPs server has a public IP and a private IP. When an INVITE arrives,
it can forward it to one of the Asterisk servers and Asterisk responds with
a 200 OK. The problem starts when I receive the ACK (from Twilio). The ACK
starts bouncing between the public IP and Private IP of the OpenSIPs
server. It doesn't reach the Asterisk server and eventually times out. I
hope someone can help me with this. Thanks in advance.

Here is my configuration:

####### Routing Logic ########
> route {
>
>     if (is_method("INVITE")) {
>         rtpproxy_engage();
>     }
>
>     if ($rm=="INVITE") {
>
>         lb_start_or_next(1,"pstn");
>     }
>
>     t_check_trans();
>     record_route();
>
>     t_on_failure("GW_FAILOVER");
>
>     # route the request
>     if (!t_relay()) {
>         sl_reply_error();
>     }
>
>     exit;
> }
>
> route[RELAY] {
>     if (!t_relay()) {
>         sl_reply_error();
>     }
>     exit;
> }
>
> failure_route[GW_FAILOVER] {
>     if (t_was_cancelled()) {
>         exit;
>     }
>     # failure detection with redirect to next available trunk
>     if (t_check_status("(408)|([56][0-9][0-9])")) {
>         xlog("Failed trunk $rd/$du detected \n");
>     }
> }
>

-- 
- Sreeram
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