[c-nsp] IP SLA issue

[Jay Hennigan]

On 12/5/12 9:10 PM, Ali Sumsam wrote:
> Hi All,
> I have a very simple configuration I am having problem with.
> 
> track 2 rtr 1 reachability
> !
> ip sla 1
>  icmp-echo 10.1.18.49 source-ip 10.0.254.30
>  timeout 500
>  frequency 3
> ip sla schedule 1 life forever start-time now
> !
> ip route 0.0.0.0 0.0.0.0 10.0.254.25 50 track 2
> ip route 0.0.0.0 0.0.0.0 10.0.254.17 80
> !
> 
> Sometimes even if i can ping 10.1.18.49 with the source ip of 10.0.254.30
> successfully but that track says its down. what could be the reason.

A single missed ping or high CPU causing latency >500 ms could be two
reasons.

Try:

track 2 rtr 1 reachability
 delay down 10 up 60

This will require three consecutive missed pings (at frequency 3) to
flag the primary route down, about 10 seconds, and require it to be up
for 60 seconds before declaring it good.

For serial links and the like this will prevent nuisance flapping while
ensuring that a marginal link stays down.  Tweak as needed for
relatively rapid detection of a down link and ensuring stability before
cutting back.

If you want failover within three or four seconds, increase frequency to
1 and change delay down to 3 or 4, for example.


   show track 2

and

   show ip sla statistics 1 detail

may give more info on what is going on in your particular case.



--
Jay Hennigan - CCIE #7880 - Network Engineering - jay at impulse.net
Impulse Internet Service  -  http://www.impulse.net/
Your local telephone and internet company - 805 884-6323 - WB6RDV