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

For NerveCenter to detect a network condition or correlate network conditions, someone must specify how NerveCenter is to detect and react to one or more conditions. Such a specification is called a behavior model. Some behavior models ship with NerveCenter -- these are called predefined behavior models -- and others you must write to handle site-specific conditions.

When writing a behavior model, you must answer the following questions:

• What condition or conditions do I want to detect?

  Although NerveCenter can receive status information from a number of sources, the most common source of such information is an SNMP agent on a managed node. Therefore, in most cases, you must decide whether the behavior model will be poll driven or event driven. That is, will you poll the agent's MIB for status information, look for SNMP traps, or both?

  NerveCenter provides two objects -- polls and trap masks -- that enable you to get information from SNMP agents. For an overview of these objects, see the section Detecting Conditions.

• What network conditions, or states, do I want to keep track of?

  Each behavior model includes at least one alarm, and the definition of each alarm consists primarily of a state diagram. For example, an alarm that tracks the status of a managed node's SNMP agent might have the following terminal states:

  • Normal
  • Device Unreachable
  • Agent Down
  • Device Down

    The state of such an alarm changes as related polls and trap masks gather new information.

    For an overview of alarms, see the section Tracking Conditions.

• What set of nodes do I want to manage?

  A particular behavior model may not be intended for all managed devices. NerveCenter enables you to specify the set of devices that a model will manage using the following objects: nodes, property groups, and properties.

  For an overview of the roles these objects play in a behavior model, see the section Monitoring a Set of Nodes.