Setting up a probe based SNMP monitor is quite simple; however, there does seem to be some confusion out there about what to use as the Parameter Name and how to call the value in the alert description. Hopefully this will clear things up but if you do still have questions after reading this blog entry please leave a comment or contact me using the link above.
Before setting up the monitor you need to discover your SNMP device(s).
Once your devices have been discovered you need to create your new SNMP probe based simple event monitor..
Then set the general properties for the monitor making sure your monitor target is set to SNMP Network Device..
Next, set the object identifier for your first expression. This will be the OID of the object you are querying; in this case the temperature value from an environmental probe is being monitored..
The next stage is to build your expression and this seems to be the part where most of the confusion is lying. To return the value of the OID you need to enter /DataItem/SnmpVarBinds/SnmpVarBind[1]/Value in the Parameter Name field. Then complete the expression by using the Operator and Value fields which are self explanatory..
Once completed, continue to follow the unit monitor wizard to build a second expression in the same way as the two previous steps above. Then comes mapping your monitor conditions to a health state - so, for example, put health state into Warning if the first event has been raised and put health state to healthy if the second event has been raised..
The last step is to configure the alert settings which are pretty straight forward until you decide that you would like the value of the OID query in the alert description. To return this value enter $Data/Context/SnmpVarBinds/SnmpVarBind[1]/Value$
along with any other static text you may want..
I hope this is short but descriptive enough to help anyone struggling with setting up an SNMP probe based monitor.
Happy Monitor Creating :-)