Configuring Embedded Event Manager
This chapter describes how to use the embedded event manager (EEM) to monitor and manage the Catalyst 3750 switch and how to configure it. Unless otherwise noted, the term switch refers to a standalone switch or a switch stack.
Note
For complete syntax and usage information for the commands used in this chapter, see the command reference for this release and the Cisco IOS Configuration Fundamentals and Network Management Command Reference, Release 12.3T. For complete configuration information, see the Cisco IOS Network Management Configuration Guide, Release 12.4T.
This chapter consists of these sections:
•
Understanding Embedded Event Manager
•
Configuring Embedded Event Manager
•
Displaying Embedded Event Manager Information
Understanding Embedded Event Manager
The embedded event manager (EEM) monitors key system events and then acts on them though a set policy. This policy is a programmed script that you can use to customize a script to invoke an action based on a given set of events occurring. The script generates actions such as generating custom syslog or Simple Network Management Protocol (SNMP) traps, invoking CLI commands, forcing a failover, and so forth. The event management capabilities of EEM are useful because not all event management can be managed from the switch and because some problems compromise communication between the switch and the external network management device. Network availability is improved if automatic recovery actions are performed without rebooting the switch,
See the EEM Configuration for Cisco Integrated Services Router Platforms Guide for examples of EEM deployment.
Figure 33-1 shows the relationship between the EEM server, the core event publishers (event detectors), and the event subscribers (policies). The event publishers screen events and when there is a match on an event specification that is provided by the event subscriber. Event detectors notify the EEM server when an event occurs. The EEM policies then implement recovery based on the current state of the system and the actions specified in the policy for the given event.
Figure 33-1 Embedded Event Manager Core Event Detectors
These sections contain this conceptual information:
•
Event Detectors
•
Embedded Event Manager Actions
•
Embedded Event Manager Policies
•
Embedded Event Manager Environment Variables
Event Detectors
EEM software programs known as event detectors determine when an EEM event occurs. Event detectors are separate systems that provide an interface between the agent being monitored, for example SNMP, and the EEM polices where an action can be implemented. Event detectors are generated only by the master switch. CLI and routing processes also run only from the master switch.
Note
The stack member switch does not generate events and does not support memory threshold notifications or IOSWdSysmon event detectors.
EEM allows these event detectors:
•
Application-specific event detector- Allows any EEM policy to publish an event.
•
IOS CLI event detector- Generates policies based on the commands entered through the CLI.
•
GOLD event detector- Publishes an event when a GOLD failure event is detected on a specified card and subcard.
•
Counter event detector-Publishes an event when a named counter crosses a specified threshold.
•
Interface counter event detector- Publishes an event when a generic Cisco IOS interface counter for a specified interface crosses a defined threshold. A threshold can be specified as an absolute value or an incremental value.For example, if the incremental value is set to 50 an event would be published when the interface counter increases by 50.
•
None event detector- Publishes an event when the event manager run CLI command executes an EEM policy. EEM schedules and runs policies on the basis on an event specification within the policy itself. An EEM policy must be manually identified and registered before the event manager run command executes.
•
Online insertion and removal event detector-Publishes an event when a hardware insertion or removal (OIR) event occurs.
•
Resource threshold event detector- Generates policies based on global platform values and thresholds. Includes resources such as CPU utilization and remaining buffer capacity. Applies only to the master switch.
•
SNMP event detector- Allows a standard SNMP MIB object to be monitored and an event to be generated when the object matches specified values or crosses specified thresholds.
•
Syslog event detector- Allows for screening syslog messages for a regular expression pattern match. The selected messages can be further qualified, requiring that a specific number of occurrences be logged within a specified time. A match on a specified event criteria triggers a configured policy action.
•
Timer event detector
Publishes events for these timers:
–
An absolute-time-of-day timer publishes an event when a specified absolute date and time occurs.
–
A countdown timer publishes an event when a timer counts down to zero.
–
A watchdog timer publishes an event when a timer counts down to zero. The timer automatically resets itself to its initial value and starts to count down again.
–
A CRON timer publishes an event by using a UNIX standard CRON specification to define when the event is to be published. A CRON timer never publishes events more than once per minute.
•
Watchdog event detector (IOSWDSysMon). This detector applies only to the master switch.
Publishes an event when one of these events occurs:
–
CPU utilization for a Cisco IOS process crosses a threshold.
–
Memory utilization for a Cisco IOS process crosses a threshold.
Two events can be monitored at the same time, and the event publishing criteria requires that one or both events cross their specified thresholds.
Embedded Event Manager Actions
EEM provides actions that occur in response to an event. EEM supports these actions:
•
Modifying a named counter.
•
Publishing an application-specific event.
•
Generating an SNMP trap.
•
Generating prioritized syslog messages.
•
Reloading the Cisco IOS software.
•
Reloading the switch stack.
•
Reloading the master switch in the event of a master switchover. If this occurs, a new master switch is elected.
Embedded Event Manager Policies
EEM can monitor events and provide information, or take 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 policy that is defined within the CLI configuration. It is a concise method for defining event screening criteria and the actions to be taken when that event occurs. Scripts are defined on the networking device by using an ASCII editor. The script is then copied to the networking device and registered with EEM.
You use EEM to write and implement your own policies using the EEM policy tool command language (TCL) script. When you configure a TCL script on the master switch and the file is automatically sent to the member switches. The user-defined TCL scripts must be available in the member switches so that if the master switch changes, the TCL scripts policies continue to work.
Cisco enhancements to TCL in the form of keyword extensions facilitate the development of EEM policies. These keywords identify the detected event, the subsequent action, utility information, counter values, and system information.
For complete information on configuring EEM policies and scripts, see the Cisco IOS Network Management Configuration Guide, Release 12.4T.
Embedded Event Manager Environment Variables
EEM uses environment variables in EEM policies. These variables are defined in a EEM policy tool command language (TCL) script by running a CLI command and the event manager environment command. These environment variables can be defined in EEM:
•
User-defined variables
Defined by the user for a user-defined policy.
•
Cisco-defined variables
Defined by Cisco for a specific sample policy.
•
Cisco built-in variables (available in EEM applets)
Defined by Cisco and can be read-only or read-write. The read-only variables are set by the system before an applet starts to execute. The single read-write variable, _exit_status, allows you to set the exit status for policies triggered from synchronous events.
Cisco-defined environment variables and Cisco system-defined environment variables might apply to one specific event detector or to all event detectors. Environment variables that are user-defined or defined by Cisco in a sample policy are set by using the event manager environment global configuration command. You must defined the variables in the EEM policy before you register the policy.
For information about the environmental variables that EEM supports, see the Cisco IOS Network Management Configuration Guide, Release 12.4T.
Configuring Embedded Event Manager
These sections contain this configuration information:
•
Registering and Defining an Embedded Event Manager Applet
•
Registering and Defining an Embedded Event Manager TCL Script
For complete information about configuring embedded event manager, see the Cisco IOS Network Management Configuration Guide, Release 12.4T.
Registering and Defining an Embedded Event Manager Applet
Beginning in privileged EXEC mode, perform this task to register an applet with EEM and to define the EEM applet using the event applet and action applet configuration commands.
Note
Only one event applet command is allowed in an EEM applet. Multiple action applet commands are permitted. If you do not specify the no event and no action commands, the applet is removed when you exit configuration mode.
|
|
|
Step 1 |
configure terminal |
Enter global configuration mode. |
Step 2 |
event manager applet applet-name |
Register the applet with EEM and enter applet configuration mode. |
Step 3 |
event snmp oid oid-value get-type {exact | next} entry-op {gt | ge | eq | ne | lt | le} entry-val entry-val [exit-comb {or |and}] [exit-op {gt | ge | eq | ne | lt | le}] [exit-val exit-val] [exit-time exit-time-val] poll-interval poll-int-val |
Specify the event criteria that causes the EEM applet to run. (Optional) Exit criteria. If exit criteria are not specified, event monitoring is re-enabled immediately. |
Step 4 |
action label syslog [priority priority-level] msg msg-text |
Specify the action when an EEM applet is triggered. Repeat this action to add other CLI commands to the applet. • (Optional) The priority keyword specifies the priority level of the syslog messages. If selected, you need to define the priority-level argument. • For msg-text, the argument can be character text, an environment variable, or a combination of the two. |
Step 5 |
end |
Exit applet configuration mode and return to privileged EXEC mode. |
This example shows the output for EEM when one of the fields specified by an SNMP object ID crosses a defined threshold:
Switch(config-applet)# event snmp oid 1.3.6.1.4.1.9.9.48.1.1.1.6.1 get-type exact entry-op
lt entry-val 5120000 poll-interval 10
These examples show actions that are taken in response to an EEM event:
Switch(config-applet)# action 1.0 syslog priority critical msg "Memory exhausted; current
available memory is $_snmp_oid_val bytes"
Switch (config-applet)# action 2.0 force-switchover
Registering and Defining an Embedded Event Manager TCL Script
Beginning in privileged EXEC mode, perform this task to register a TCL script with EEM and to define the TCL script and policy commands.
|
|
|
Step 1 |
configure terminal |
Enter global configuration mode. |
Step 1 |
show event manager environment [all | variable-name] |
(Optional) The show event manager environment command displays the name and value of the EEM environment variables. (Optional) The all keyword displays the EEM environment variables. (Optional) The variable-name argument displays information about the specified environment variable. |
Step 2 |
configure terminal |
Enter global configuration mode. |
Step 3 |
event manager environment variable-name string |
Configure the value of the specified EEM environment variable. Repeat this step for all the required environment variables. |
Step 4 |
event manager policy policy-file-name [type system] [trap] |
Register the EEM policy to be run when the specified event defined within the policy occurs. |
Step 5 |
exit |
Exit global configuration mode and return to privileged EXEC mode. |
This example shows the sample output for the show event manager environment command:
Switch# show event manager environment all
1 _cron_entry 0-59/2 0-23/1 * * 0-6
3 _syslog_pattern .*UPDOWN.*Ethernet1/0.*
4 _config_cmd1 interface Ethernet1/0
This example shows a CRON timer environment variable, which is assigned by the software, to be set to every second minute, every hour of every day:
Switch (config)# event manager environment_cron_entry 0-59/2 0-23/1 * * 0-6
This example shows the sample EEM policy named tm_cli_cmd.tcl registered as a system
policy. The system policies are part of the Cisco IOS image. User-defined TCL scripts must
first be copied to flash memory.
Switch (config)# event manager policy tm_cli_cmd.tcl type system
Displaying Embedded Event Manager Information
To display information about EEM, including EEM registered policies and EEM history data, see the Cisco IOS Configuration Fundamentals and Network Management Command Reference, Release 12.3T.