Cisco IOS IP Service Level Agreements (SLAs) help network administrators ensure that a high level of voice and data communication quality is maintained. Cisco IP SLA operations are a proactive method of reliably measuring network performance. IP SLA data can be retrieved and trended with an SNMP Performance trender to enable users to graph performance over time. Cisco IP SLA and SNMP should be in the tool belt of every network administrator. Pair these technologies with a NetFlow analyzer and you’ve got a great setup to help troubleshoot most network problems.

The purpose of this blog is to outline some of the IP SLA configuration changes in newer versions of Cisco’s IOS.

We’ve written a 4-part blog in the past that focuses on the following IP SLA operations:

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Hello Everyone,

If you would like to see other blogs on how to setup IP SLAs check out these links.

IP SLA  – ICMP Echo – 2 of 4
IP SLA – TCP Connect – 3 of 4
IP SLA - HTTP - 4 of 4 

I’m going to be putting together a four part series on some common Cisco IP SLA monitor configurations.  Cisco IP SLAs are great ways to get statistics on different types of communications between routers.  They’re relatively simple to set up, and reports can be generated by an SNMP trender.

focus on the Jitter monitor.  You can get a ton of information from the Jitter monitor, starting with latency, Packet Loss, and Jitter.  If the router’s clocks are synchronized you can also get the latencies for each way.  By adding a VoIP codec to the monitor, the router can generate the Mean Opinion Score (MOS), and the Impairment/calculated planning impairment factor (ICPIF) score.

Check out Plixer’s white paper on setting up the Jitter operation.  It will walk you through setting up a Jitter monitor, how to trend the statistics, and generate reports.

If you plan on using the jitter operation to monitor VoIP, pay special attention to make sure that you are using the codec that matches the actual codec being used.

It is also important to have realistic expectations on MOS values pertaining to each codec.  Although Cisco’s scale is 1-5 in their documentation, production environments will not see a 5.  The chart below will help in determining how well your communications are doing.

Cisco VoIP Codec White Paper

Scrutinizer Netflow Analyzer has a My View page that contains gadgets that can integrate with third party applications.  One of these applications is Denika which can trend the IP SLA statistics.  If you have Scrutinizer and Denika ask us about a custom VoIP gadget to display VoIP IP SLA Statistics.

Check out Part 2 of the IP SLA series.

Raul