Assigning a new RTPEngine for a call for the sake of failover - sr-users

15 Apr 2023


      Hello,
I am trying to implement RTPEngine failover, where if a selected RTPEngine node fails in the middle of the call (and not responding NG requests), I want to select an alternative node. However, when I call rtpengine_manage(), it does not seem to select an alternative node in case of a failure. To address this, I have attempted to check if $avp(RTP_INSTANCE) is null after calling rtpengine_manage(), and then use rtpengine_delete() to forget the selected RTPEngine node for the specific call, with the expectation that Kamailio would assign a new RTPEngine node for subsequent SIP message retries. However, it appears that rtpengine_delete() does not have the desired effect in this regard.
Here is an excerpt of my code for reference:
```
route[RTP] {
#!ifdef WITH_RTPENGINE
    if (has_body("application/sdp")) {
    	if ($avp(x_source) == "INTERNAL") {
    		rtpengine_manage("replace-session-connection replace-origin direction=internal direction=external");
    	}
    	else if ($avp(x_source) == "EXTERNAL") {
    		rtpengine_manage("replace-session-connection replace-origin direction=external direction=internal");
    	}
if ($avp(RTP_INSTANCE) == $null) {
    		rtpengine_delete();
    		drop();
    	}
    }
#!endif
}
```
Can you please advise on how I can achieve the desired failover behavior? Is there another function similar to `rtpengine_reset_call` that can make Kamailio forget the RTPEngine node for a specific call?
Thank you!