IP SLA Topology Question

Question

Hi, looking for a bit of advice on using IP SLA.

We have an MPLS network but very little communication goes between the sites.  Almost all traffic is between the 18 sites and the headquarters (a site in MPLS).  So while it's fully meshed by MPLS terms, it behaves more like a hub-and-spoke most of the time.  The obvious difference is when one site does a VoIP call to the others but that's small in comparison with the rest of the traffic (most sites only have a few users).

In this scenario, is using IP SLA advantageous?  If so, which site should be the source vs. destination?  i.e. should HQ be the source and a remote site the destination, or vice versa.

I "think" IP SLA would be useful but I'm not certain that it'll give me more information than netflow will give, given my topology.  So, any advice or expertise would be appreciated.

fcaron · Accepted Answer

Tks NRMS.

Csweet, I think the IP SLA vs Netflow question has little to do with the topology but more what you try to achieve.

IPSLA will give you interesting metrics that characterize pretty well the user experience and the perceived quality of service. For ex, if you create VoIP Operations with IP SLA, you'll get Mean Opinion Score (MOS), Jitter that characterize the "average" quality of VoIP calls going through your infrastructure, whether they are between sites or between sites and HQ. Just chose where you want to deploy the operations (i.e. what segment you want to measure). In your situation, I would create them between all pair of sites. 18 sites and 1 HQ is not that high in terms of number of combinations. Note that I wrote "characterize the average quality of VoIP calls" because IP SLA does not process Call Details Records (CDR) that can give you the QOS of each individual call. Cisco's IP SLA technology is about generating artificial traffic mimicking real traffic (e.g. VoIP Operations place pseudo VoIP calls) in order to measure what this traffic experiences when it goes through the network (e.g. jitter, delay, packet loss...)

Netflow will give you very little information related to user's perception of the quality of the network, but will give you helpful data in terms of the traffic volume that is going across your network. You'll get overall volume broken down by users, application ports, source, destination... Great info to know what traffic is clogging your interfaces (NPM gives you that), detecting trends, plan bandwidth increase in the coming months, detect some types of security threats (that can be detected by some types of traffic).

Both are very complementory, I would suggest to run both.