10 Aug
2023
10 Aug
'23
4:01 p.m.
Hello!
I am looking into a problem where we have Kamailio forwarding calls to two
or more "recording-clients". I will try my best to describe the problem and
would appreciate it if someone has an idea what to do. Please feel free to
ask if you think I have forgotten to describe something that might be
important or something is unclear in what I have written.
We use use_dns_failover=yes and dns_srv_lb=yes so calls get load balancing
to the "recording-clients". There is also the t_set_fr(60000,1000)
parameter set so that if there is no response within 1 second it would try
the next recording-client. The SRV record points to two or more recording
clients.
It now happens that the recording-clients sometimes have some kind of
temporary problem so it will respond with a 503 after 5 seconds.
What happens is that after the 1 second timeout trying to get the INVITE
through to the first recording-client Kamailio will internally generate a
408. This will cause it to failover to another recording-client which
happily takes care of the INVITE and responds properly with a 200 OK.
Everything would have been just fine except for the fact that the first
recording-client is just slow and finally responds with a 503. This 503 is
not relayed backwards since a 200 has already been forwarded back to the
caller. But when receiving the 503 Kamailio will initiate a new INVITE
which is trying to set up a new call to a recording client. It looks like
it is doing a new failover regardless if it already has done a failover for
this failed transaction.
I don't want Kamailio to send that last INVITE when receiving the 503. How
can I configure Kamailio to disregard the last 503 (except for responding
with an ACK) and not initiate a new INVITE?
I have tried a lot of different changes to the configuration but failed to
achieve this, unfortunately. Do I need to use the dispatcher module to
achieve this?
/Mattis