How can I monitor bandwidth class consumption via SNMP?

[riverbedjo]

I've been using the MIB provided by Stingray to attempt to monitor when a bandwidth class is reaching its cap but I'm not having much luck. The values returned by bandwidthClassBytesOutLo.IOD seem to be the total value of bytes output.

If I look at the graphs in the admin interface for a particular class it shows me exactly what I want.

How I can replicate this so I can alert & report on it via snmp?

[owen · Accepted solution]

The value you are monitoring is an SNMP Counter - it's an increasing count of the data transferred. To get a bandwidth rate, you need to sample the counter periodically (for example, every 10 seconds), the difference between the two samples will be the data transferred in that interval.

There are a few code examples that illustrate this technique - see Gathering statistics from a cluster of Traffic Managers for starters.  And many SNMP monitoring agents will perform this rate calculation for you (ever-increasing counters are a common pattern in SNMP).  Some of our customers have recommended Monitoring Stingray using MRTG or using PRTG Network Monitor.

Alternatively, you could create an action that was triggered when the bwlimited event was raised (this is one of the license key events).  Actions can raise SNMP traps (amongst other possibilities) - see Feature Brief: Event Handling in Stingray Traffic Manager