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Tracking Conditions

NerveCenter tracks each detected network condition using one or more alarms. The scope of an alarm is variable: an alarm can represent the state of an interface on a device, the device itself, or an entire enterprise. Many instances of an alarm can exist simultaneously (unless the alarm is enterprise-wide in scope).

Each alarm is basically a finite state machine. It consists of a series of states and transitions between the states. Each transition is initiated by one or more input events and can produce one or more output events. This state machine is represented in NerveCenter by a state transition diagram.

For example, you could use the following state diagram to monitor the traffic on an interface.

Monitoring the Load on an Interface

In this diagram, the states are low, medium, and high, and the transitions are lowLoad, mediumLoad, and highLoad. The initial state of the interface-traffic alarm is low. The instantiation of an alarm instance and a transition to the medium state occur when the alarm manager receives the trigger mediumLoad from a poll that is gathering information about an interface. Note that the trigger name and the transition name are the same.

When a transition occurs, not only does the alarm's state change, but NerveCenter can perform actions. These actions are defined as part of the transition and can include such things as sending e-mail to an administrator or notifying a network management platform that a condition has been detected. For an overview of NerveCenter's alarm actions, see the section Responding to Conditions.