Hi Federico,

"use_dns_cache=on" this is on be default.

"use_dns_failover=on" this is off by default, changing to "on" did the trick, auto failover to next SRV server is working quickly, as expected now.

Thanks for the pointer.

JR -- JR Richardson Engineering for the Masses Chasing the Azeotrope

Hi, if you want failover support, you need to have a couple of core dns parameters enabled: https://www.kamailio.org/wiki/cookbooks/5.2.x/core#use_dns_cache

and

https://www.kamailio.org/wiki/cookbooks/5.2.x/core#use_dns_failover

The latter defaults to off.

Cheers,

Federico

On Thu, Jun 6, 2019 at 10:10 PM JR Richardson jmr.richardson@gmail.com wrote:

...

Hey All,

I'm in the lab testing kamailio 5.2 with DNS SRV records. The scenario is simple, using dispatcher with hard coded IP URIs [sip:10.10.10.10:5060] and also a DNS name URI [sip:sip.domain.com]. There are 2 SRV servers.

The DNS SRV records are setup and resolving OK, during startup, kamailio list the DNS name in the dispatcher list.

During a call scenario, when the dispatcher selects the DNS name URI for the next destination, the TM module takes over, resolves the _sip._udp.sip.domain.com for both SRV records OK and sends the call to the first SRV server in the list. But if I take the first SRV server offline, make another call, the TM module does not route to the second SRV server until the DNS record timeout is reached, in my lab was set for 300 seconds. I decreased the DNS SRV record TTL down to 5 seconds with same results above, but 5 seconds lapse when TM routes call to next SRV server.

I think this is working as expected but not sure if this is by design so my question is, should the TM module route to another SRV server in the list in the event of a no response timeout or send the transaction back to the dispatcher to select another target?

Should I play around with the TM Module parameter "max_noninv_lifetime" to get quicker results or it is better to have DNS SRV record TTL set really low?

Thanks.

JR