IP SLA and RTR

On August 12, 2010, in Uncategorized, by Darren

I was tasked without setting up some IP SLA’s over our network to check performance at various points in the network. I’m not going to go hardcore into how to configure it, as Cisco has an excellent guide right here: http://www.cisco.com/en/US/docs/ios/12_4/ip_sla/configuration/guide/hsjitter.html

There is something I wanted to point out though. I installed a 3750 in the core running the actual tests. IP SLA requires another Cisco router to actually respond to those tests, basically an IP SLA Responder. It seemed to me that a lot of devices we had simply did not support IP SLA, or at least I though.
IP SLA used to be called something completely different. In IOS release 12.1 (4) they released a feature called SAA Monitor. The commands used to configure it were completely different to IP SLA. Basically instead of typing:

Cisco(config)#ip sla responder

The command was instead:

Cisco(config)#rtr responder
The beauty is they work together perfectly. i.e. Router1 could be running 12.4 with IP SLA while RouterB would be running 12.1 with RTR RESPONDER. Both will still function perfectly.
One more thing to remember, a lot of devices cannot be the primary SLA monitor, but most CAN be the responder.

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