[dns-operations] DNS load-balancing/failover using an ASR 9xxx (few questions)

[Marcelo Gardini do Amaral]

On Fri, Aug 15, 2014 at 09:22:02AM +0200, Anand Buddhdev wrote:
> On 15/08/2014 00:00, Nat Morris wrote:
> 
> > BGP sessions between the ASR 9xxxx and each DNS server in the cluster,
> > ExaBGP running on them announcing their loopback/service /32 + /128
> > address(es).
> > 
> > Health check scripts on each service to probe for service ability,
> > retract the announcement upon failure.
> 
> We are doing this exact same thing on many RIPE NCC DNS servers, and it
> works very well. The other advantage of BGP is that as soon as you
> withdraw the announcement, the router stops sending traffic to the
> server. With OSPF, you have timeouts of several seconds before traffic
> stops arriving at a dead server.

You can tweak OSPF timers like "hello" and "dead" interval in order to
increase the responsiveness of the health check.

Cheers,

--
Marcelo Gardini