IP SLA (RTT delay)

Rojer-bkk · ‎11-29-2011

Hi Expert,

I have two links primary and backup with different provider. Actually, i got RTT 40 ms when i ping test from HQ to branch. Some days i got RTT over 400 ms for long time (2-3 hrs) cause provider node has problem. It effect to voice application so i need to switchover to backup link. Do you have mechanism to detect RTT delay to switchover to backup link if it's over threshold? Please help to advise me.

Thanks

smitesh kharecha · ‎11-29-2011

Hi Rojer,

Yes.

Configure IP SLA and track, such that ooif your RTT ges abve X level, it will make track down and apply that track to static route. Once track goes down, it will remove the static route.

eg,

R1 ------------------- R2

Config R1 as follow

ip sla 1

icmp-echo 2.2.2.2 source-interface Loopback0

threshold 200

ip sla schedule 1 life forever start-time now

track 1 rtr 1

ip route R2's IP & subnet track 1 (this will be your main link)

ip route R2's IP & subnet 20 (this will be your backup link)

HTH,

Smitesh

Rojer-bkk · ‎11-29-2011

Hi Smitesh,

Thanks for reply. For configure above, if RTT above 200 the backup route will be use but If link flapping so the two routes could switchover between main and backup. How can i setup configure to prevent this concern?

smitesh kharecha · ‎11-30-2011

Hi Rojer,

Under track configuration, you can use delay before it changes the state.

HTH,

Smitesh