IP SLA ICMP Echo Operation

[thecompnerd]

On a Nexus 7K, I want to configure IP SLA ICMP Echo to track an IP across a fiber link and remove a route if the receive side doesn't respond to ping after x amount of time.  Is 'timeout' the appropriate parameter to use to accomplish my goal?  Let's say I want to send one ping every second and remove the route if a response is not received after 15 seconds, is this the correct way to do so?

ip sla 1
  icmp-echo 1.1.1.2
  frequency 1
  timeout 15000
!
ip sla schedule 1 life forever start-time now
!

[Francesco Molino]

Hi 

Timeout is the attribute your talking about. 

However, frequency has to be higher than timeout. This is best practices.

In your example you're sending an icmp packet every seconds but have a timeout of 15s. Why do you want to wait 15s for a icmp reply? 

[thecompnerd]

Thanks for the reply, Francesco.

The idea is to consistently send a ping to the remote device and remove the route if the device becomes unresponsive.  I can't ping the device more than once per second as it has an ICMP rate limiter enabled and won't respond more than once per second.  Also, I want to be absolutely sure that the remote device is down, not just experiencing some packet loss, before we remove the route - hence, waiting 15 seconds.  If I'm going about this the wrong way, can you please provide an example of how to do it?

[Francesco Molino]

Hi,

I understand that you want to be sure and that's fair enough. However, waiting 15 seconds for an icmp reply it's not gonna happen or you would be better to switch to other link.

Anyway, If you want to wait 15 s, then you need to send icmp packet every 20s for example. But by experience, I would recommend sending a ping every 5s with a timeout of 3s let's say it's good.

you can also use in combination the attribute threshold. For example: if you send a icmp packet every 20 seconds with a timeout of 15s. if the threshold is set to 10s, you can trigger another ip sla with more aggressive icmp like very 2s

[anoop verma]

https://anoopvermanetworking.blogspot.in/