Information About Writing Eem Policies Using The Cisco Ios Cli - Cisco Catalyst 2960 series Configuration Manual

Information About Writing EEM Policies Using the Cisco IOS CLI

• If the action snmp-trap command is used, the snmp-server enable traps event-manager command
Information About Writing EEM Policies Using the Cisco IOS CLI
Embedded Event Manager Policies
EEM offers the ability to monitor events and take informational or corrective action when the monitored
events occur or a threshold is reached. An EEM policy is an entity that defines an event and the actions to be
taken when that event occurs. There are two types of EEM policies: an applet or a script. An applet is a simple
form of policy that is defined within the CLI configuration. A script is a form of policy that is written in Tool
Command Language (Tcl).
EEM Applet
An EEM applet is a concise method for defining event screening criteria and the actions to be taken when
that event occurs. In applet configuration mode, three types of configuration statements are supported. The
event commands are used to specify the event criteria to trigger the applet to run, the action commands are
used to specify an action to perform when the EEM applet is triggered, and the set command is used to set
the value of an EEM applet variable. Currently only the _exit_status variable is supported for the set command.
Only one event configuration command is allowed within an applet configuration. When applet configuration
mode is exited and no event command is present, a warning is displayed stating that no event is associated
with this applet. If no event is specified, this applet is not considered registered. When no action is associated
with this applet, events are still triggered but no actions are performed. Multiple action configuration commands
are allowed within an applet configuration. Use the show event manager policy registered command to
display a list of registered applets.
Before modifying an EEM applet, be aware that the existing applet is not replaced until you exit applet
configuration mode. While you are in applet configuration mode modifying the applet, the existing applet
may be executing. It is safe to modify the applet without unregistering it. When you exit applet configuration
mode, the old applet is unregistered and the new version is registered.
The action configuration commands are uniquely identified using the label argument, which can be any string
value. Actions are sorted in ascending alphanumeric key sequence using the label argument as the sort key,
and they are run using this sequence.
The Embedded Event Manager schedules and runs policies on the basis of an event specification that is
contained within the policy itself. When applet configuration mode is exited, EEM examines the event and
action commands that are entered and registers the applet to be run when a specified event occurs.
EEM Script
Scripts are defined off the networking device using an ASCII editor. The script is then copied to the networking
device and registered with EEM. Tcl scripts are supported by EEM.
EEM allows you to write and implement your own policies using Tcl. Writing an EEM policy involves:
• Selecting the event for which the policy is run.
Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)
1684
must be enabled to permit SNMP traps to be sent from the Cisco IOS device to the SNMP server. Other
relevant snmp-server commands must also be configured; for details see the action snmp-trap command
page.