Cisco: How to configure simple IP SLA monitor

Before we begin let’s see what is this SLA term, for those of us who are not very familiar with the Service Provider terms. IP Service Level Agreements (SLAs) enable customers to assure new business-critical IP applications, as well as IP services that utilize data, voice, and video, in an IP network. With Cisco IOS IP SLAs, users can verify service guarantees, increase network reliability by validating network performance, pro actively identify network issues assure an easy way to deploy new IP services. Cisco IOS IP SLAs use active monitoring, enabling the measurement of network performance and health.

For the following how-to please have a quick look into the topology. As you can see I have a basic routing topology, imported from another tutorial from FirstDigest, and let’s assume that we want to monitor the line between R1 and TEST-RT. For this we will configure a very simple IP SLA monitor, based on icmp echo packets, which will measure our RTT (Round Trip Time) or latency and provide us with valuable informations. For example in case of VoIP problems we can check the latency and in case of a value bigger than 200 ms (220 ms maximum accepted for the voice service to function properly) we will know from where are the problems generated.  Of course IP SLA can have more complex configuration under Cisco IOS (e.g. http or ftp transfer to check if the service provider assure us the bandwidth specified in the contract).

One personal advice from my experience. Even if all the data and information provided by IOS IP SLA monitor can be checked with “show…” commands, I would advice you to get a third party software that can interpret this data for you and draw nice graphs or store them in an archive for you. This kind of software are MRTG, Weathermap, Nagios, RRDtool and others (I put here only the free ones).

Please check the how-to by clicking the image below:

IP SLA monitor