Designing and Managing Behavior Models - Behavior Models and Their Components - Behavior Models - Detecting Conditions -
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Detecting Conditions

In the typical situation where your behavior model is either polling, or looking for a trap from, an SNMP agent, you detect network conditions by creating polls and trap masks.

A poll contains a poll condition that refers to a single MIB base object. For example, the following poll condition looks at an attribute of the ip base object (1.3.6.1.2.1.4):

When NerveCenter polls an agent on a device, NerveCenter evaluates the poll condition against information stored in the agent's MIB. In the case of the poll condition shown above, NerveCenter would check the value of the ipForwarding attribute and compare it to 1. If the value of ipForwarding is 1 -- indicating that the device is a gateway -- the poll generates a trigger. Every poll must be capable of generating at least one trigger.

A trap mask describes the contents of an SNMP trap. This description can be very general, such as "generic trap 4." Or it can be very specific and include an enterprise OID, a specific trap number, and the contents of the trap's variable bindings. In either case, if the NerveCenter server receives an SNMP trap that matches the description given in a trap mask, that trap mask generates a trigger. Like the triggers generated by polls, this trigger can affect the state of one or more alarms.