[SR-Users] Using DNS in Dispatcher for SRV Clarification [SOLVED]

[JR Richardson]

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 at 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