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uses a pattern match with the syslog messages. It also relies on a timer event detector to detect that a certain
time and date has occurred.
Policy-Based Event Response
When the EEM has detected an event, it can initiate actions in response. These actions are contained in routines
called
policy handlers
. While the data for event detection is collected, no action occurs unless a policy for
responding to that event has been
registered
. At registration, a policy informs the EEM that it is looking for
a particular event. When the EEM detects the event, it enables the policy.
Reliability Metrics
The EEM monitors the reliability rates achieved by each process in the system. These metrics can be used
during testing to determine which components do not meet their reliability or availability goals so that corrective
action can be taken.
System Event Processing
When the EEM receives an event notification, it takes these actions:
•
Checks for established policy handlers:
◦
If a policy handler exists, the EEM initiates callback routines (
EEM handlers
) or runs Tool
Command Language (Tcl) scripts (
EEM scripts
) that implement policies. The policies can include
built-in EEM actions.
◦
If a policy handler does not exist, the EEM does nothing.
•
Notifies the processes that have
subscribed
for event notification.
A difference exists between scripts with policy actions and scripts that subscribe to
receive events. Scripts with policy actions are expected to implement a policy. They are
bound by a rule to prevent recursion. Scripts that subscribe to notifications are not bound
by such a rule.
Note
•
Records reliability metric data for each process in the system.
•
Provides access to EEM-maintained system information through an application program interface (API).
Embedded Event Manager Management Policies
When the EEM has detected an event, it can initiate corrective actions. Actions are prescribed in routines
called
policies
. Policies are defined by Tcl scripts (EEM scripts) written by the user through a Tcl API. (See
the
Embedded Event Manager Scripts and the Scripting Interface (Tcl), on page 44
.) Policies must be
registered before any action can be applied to collected events. No action occurs unless a policy is registered.
A registered policy informs the EEM about a particular event to detect and the corrective action to take if that
event is detected. When such an event is detected, the EEM runs the policy. You can disable a registered
policy at any time.
Cisco ASR 9000 Series Aggregation Services Router System Monitoring Configuration Guide, Release 4.2.x
43
Configuring and Managing Embedded Event Manager Policies
Embedded Event Manager Management Policies