Designing and Managing Behavior Models - Debugging a Behavior Model - Matching Triggers and Alarm Transitions - Rules for Matching -
Matching Triggers and Alarm Transitions      Auditing Behavior Models

Rules for Matching

A trigger causes an alarm transition if the identities of the trigger and the transition match -- that is, if their names, subobjects, nodes, and properties all pass comparison tests. The four comparison tests corresponding to the four parts of a trigger's identity are discussed in the upcoming subsections. The trigger must pass all four tests before it can prompt a transition.

Name Rule

A trigger's name must match the transition's name exactly.

Subobject Rule

A trigger's subobject matches a transition's subobject when any of the following statements is true:

• The transition's scope is Enterprise.
• The transition's scope is Node.
• Both the trigger's and the transition's subobjects are zero instance (baseObject.0) or are empty.
• The trigger's subobject matches the transition's subobject exactly.
• The transition's scope is instance and the instances match.
• The trigger's subobject is a wildcard ($ANY), and the transition's origin state is not Ground.
• The transition has subobject scope, the base objects are the same in the subobject for the trigger and transition, the instance in the trigger's subobject is a wildcard ($ON), and the transition's origin state is not Ground.
• The transition has instance scope, the instance in the trigger's subobject is a wildcard ($ON), and the transition is not from ground state.
• The instances in the trigger's subobject and transition's subobject match, and one of the base objects is an extension of the other.

  Here's an example of one base object extending another. MIB-II defines ifEntry, a row of data in a table of information about an interface. You access a particular instance of ifEntry using the index ifIndex. Cisco extends this interface table by defining a local interface table, which contains many additional attributes for each interface. The rows in this table are accessed using the same index used to access the rows in the MIB-II interface table.

If the transition's origin state is Ground -- that is, a new alarm instance is being created -- the following statement must also be true:

• The trigger's subobject is not $ANY or $NULL and does not contain $ON.

  The trigger can have an empty subobject.

Node Rule

A trigger's node matches a transition's node when any of the following statements is true:

• The transition's scope is Enterprise.
• The trigger's node matches the transition's node exactly.
• The trigger's node is $ANY, and the transition's origin state is not Ground.

If the transition would create a new alarm instance and therefore has no associated node, the follow statement must also be true:

• The trigger's node is not $ANY.

Property Rule

A trigger and transition pass the property test when all of the following conditions are met:

• For transitions of subobject or node scope, the transition's property is contained in the property group of the trigger's node, or the transition's property is NO_PROP.
• For transitions of subobject or node scope, the trigger's property (if it has one) is contained in the property group assigned to the trigger's node.
• For transitions of enterprise scope, the trigger's property (if it has one) must match the transition's property.

Examples of Matching Triggers and Transitions

This section presents a number of examples of triggers and transitions that do and do not match.

Example 1

A trigger named highLoad with the subobject system.0 and the node hp124 would prompt the following transitions:

• Name: highLoad
  Scope: Subobject
  Subobject: ip.0
  Node: hp124
  Property: hpws, which is contained in hp124's property group
• Name: highLoad
  Scope: Subobject
  Subobject: Unassigned (transition from Ground)
  Node: Unassigned (transition from Ground)
  Property: NO_PROP
• Name: highLoad
  Scope: Node
  Subobject: Irrelevant
  Node: hp124
  Property: hpws, which is contained in hp124's property group

  The highLoad trigger would not prompt the following transition:

• Name: highLoad
  Scope: Subobject
  Subobject: ifEntry.2
  Node: hp124
  Property: hpws, which is contained in hp124's property group

  The trigger and transition fail the subobject rule.

Example 2

A trigger named lowSpace with the subobject $ANY, the node hp124, and the property includeMe (which is contained in hp124's property group) would prompt the following transitions:

• Name: lowSpace
  Scope: Subobject
  Subobject: ifEntry.2
  Node: hp124
  Property: includeMeToo, which is contained in hp124's property group
• Name: lowSpace
  Scope: Node
  Subobject: Irrelevant
  Node: hp124
  Property: NO_PROP
• Name: lowSpace
  Scope: Subobject
  Subobject: system.0
  Node: hp124
  Property: NO_PROP

The lowSpace trigger would not prompt the following transitions:

• Name: lowSpace
  Scope: Enterprise
  Subobject: Irrelevant
  Node: Irrelevant
  Property: hpws, which is contained in hp124's property group

  The trigger and transition fail the property rule.

• Name: lowSpace
  Scope: Subobject
  Subobject: ifEntry.2
  Node: hp125
  Property: includeMe

  The trigger and transition fail the node rule.

• Name: lowSpace
  Scope: Subobject
  Subobject: Unassigned (transition from Ground)
  Node: Unassigned (transition from Ground)
  Property: NO_PROP

  The trigger and transition fail the subobject rule.

Example 3

A trigger named lowSpace with the subobject $NULL, the node $ANY, and the property NO_PROP would prompt the following transitions:

• Name: lowspace
  Scope: Node
  Subobject: Irrelevant
  Node: hp125
  Property: includeMe
• Name: lowspace
  Scope: Enterprise
  Subobject: Irrelevant
  Node: Irrelevant
  Property: dontIncludeMe

The lowSpace trigger would not prompt the following transitions:

• Name: lowspace
  Scope: Subobject
  Subobject: ifEntry.2
  Node: hp125
  Property: includeMe

The trigger and transition fail the subobject rule.

• Name: lowspace
  Scope: Subobject
  Subobject: Any string at all, including the empty string
  Node: Any node at all
  Property: NO_PROP

The trigger and transition fail the subobject rule.