Dispatcher, Failure Route and fr_timeout - sr-users

6 Jul 2015

Hi All,

I would like to reduce the time it takes for kamailio to timeout an 
initial message to a dispatcher destination so that it will select the 
next destination in the set, before, hopefully, a restransmission. In 
this case I am testing registration messages.

I came accross the t_set_fr() function in the TM module documentation 
today and have been experimenting with it for some hours. I have an 
issue where a 408 timout is sent back to the UAC before the last 
destination in the dispatcher set is selected, I suspect I am hitting 
the timeout somewhere, but I cannot see where, I presume the fr_timeout 
is set every time I issue the t_set_fr() call and the associated t_relay.

I'm just wondering if I am doing this correctly, if one of the guru's 
out there wouldnt mind casting an eyeball over this config and let me 
know if I am on the right track, or if I am going about this in the 
wrong way. Any suggestions are most welcome.

What appears to be happening is, I have 3 destinations in the dispatcher 
set, it looks like the 1st 2 are tried, which correctly timeout and are 
set inactive-probing, but on the last destination, which is working, I 
appear to be getting a 408 timeout being sent back from kamailio.

Here is a snip of my configuration:

#!define NO_RESPONSE_TIMER 250

request_route {
     t_on_failure("DISPATCHER_FAILURE");
     t_set_fr(0, NO_RESPONSE_TIMER);
     if(!ds_select_dst("1", "0")) {
         xlog("L_ERR", "No dispatcher destinations available for
$ru\n");
         sl_send_reply("500", "No destination available");
         exit;
     }
     route("RELAY")
}

route[RELAY] {
     if (!t_relay()) {
         sl_reply_error();
     }
     exit;
}

failure_route[DISPATCHER_FAILURE] {
     if (t_is_canceled()) {
         exit;
     }

     # select next destination only for local timeout
     if (t_branch_timeout() && !t_branch_replied()) {
         xlog("L_INFO", "route[DISPATCHER_FAILURE] : $rm : timeout and 
no reply ($si:$sp->$Ri:$Rp->$du)\n");
         xlog("L_INFO", "route[DISPATCHER_FAILURE] : $rm : setting $du 
to probing state");
         ds_mark_dst("ip");
         if(ds_next_dst()) {
             xlog("L_INFO", "route[DISPATCHER_FAILURE] : $rm : next 
destination selected ($du)\n");
             t_set_fr(0, NO_RESPONSE_TIMER);
             t_relay();
             exit;
         } else {
             xlog("L_INFO", "route[DISPATCHER_FAILURE] : $rm : No 
destinations available for $rd");
             send_reply("500", "No destination available");
             exit;
         }
     }
}