Configuring Embedded Event Manager

CH A P T E R
34
Configuring Embedded Event Manager
Embedded Event Manager (EEM) is a distributed and customized approach to event detection and
recovery within a Cisco IOS device. EEM offers the ability to monitor events and take informational,
corrective, or any other EEM action when the monitored events occur or when a threshold is reached.
An EEM policy defines an event and the actions to be taken when that event occurs.
This chapter tells how to use EEM and how to configure it on the Catalyst 3750 switch. For complete
syntax and usage information for the commands used in this chapter, see the switch command reference
for this release and the Cisco IOS Network Management Command Reference. For the complete EEM
document set, see these documents in the Cisco IOS Network Management Configuration Guide:
•
Embedded Event Manager Overview
http://www.cisco.com/en/US/docs/ios/netmgmt/configuration/guide/nm_eem_overview.html
•
Writing Embedded Event Manager Policies Using the Cisco IOS CLI
http://www.cisco.com/en/US/docs/ios/netmgmt/configuration/guide/nm_eem_policy_cli.html
•
Writing Embedded Event Manager Policies Using Tcl
http://www.cisco.com/en/US/docs/ios/netmgmt/configuration/guide/nm_eem_policy_tcl.html
Note
This feature is supported only on switches running the IP services image.
This chapter includes these sections:
•
Understanding Embedded Event Manager, page 34-1
•
Configuring Embedded Event Manager, page 34-6
•
Displaying Embedded Event Manager Information, page 34-7
Understanding Embedded Event Manager
EEM monitors key system events and then acts on them through 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.
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Understanding Embedded Event Manager
Figure 34-1 shows the relationship between the EEM server, the core event publishers (event detectors),
and the event subscribers (policies). The event publishers screen events and publish them 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 34-1
Embedded Event Manager Core Event Detectors
Core event publishers
Cisco
IOS
parser
text
Syslog
message
queue
OIR
events
event
manager run
CLI command
Hardware
timers
CLI
event
detector
SYSLOG
event
detector
OIR
event
detector
NONE
event
detector
Timer
event
detector
Counter
event
detector
EMBEDDED EVENT MANAGER SERVER
EEM POLICY DIRECTOR
Subscribes to receive events
and implements policy actions
EEM APPLET
EEM SCRIPT
127574
Event
subscribers
See the EEM Configuration for Cisco Integrated Services Router Platforms Guide for examples of EEM
deployment.
•
Event Detectors, page 34-2
•
Embedded Event Manager Actions, page 34-4
•
Embedded Event Manager Policies, page 34-4
•
Embedded Event Manager Environment Variables, page 34-5
•
EEM 3.2, page 34-5
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 policies 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.
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Understanding Embedded Event Manager
Note
The stack member switch does not generate events and does not support memory threshold notifications
or IOSWdSysmon 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.
•
Generic Online Diagnostics (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.
This detector also publishes an event about an interface based on the rate of change for the entry and
exit values.
•
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. This only to
the master switch.
•
Remote procedure call (RPC) event detector—Invokes EEM policies from outside the switch over
an encrypted connecting using Secure Shell (SSH) and uses Simple Object Access Protocol (SOAP)
data encoding for exchanging XML-based messages. It also runs EEM policies and then gets the
output in a SOAP XML-formatted reply.
•
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.
– The SNMP delta value, the difference between the monitored Object Identifier (OID) value at
the beginning the period and the actual OID value when the event is published, matches a
specified value.
•
SNMP notification event detector—Intercepts SNMP trap and inform messages received by the
switch. The event is generated when an incoming message matches a specified value or crosses a
defined threshold.
•
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
– 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.
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– 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)—Publishes an event only on the master switch when
– 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
These actions occur in response to an event:
•
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, which can be a bytecode (.tbc) and text (.tcl) script, is then copied to the networking device
and registered with EEM. You can also register multiple events in a .tcl file.
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, 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.
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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.
•
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.
EEM 3.2
EEM 3.2 is supported in Cisco IOS Release 12.2(52)SE and later and introduces these event detectors:
•
Neighbor Discovery—Neighbor Discovery event detector provides the ability to publish a policy to
respond to automatic neighbor detection when:
– a Cisco Discovery Protocol (CDP) cache entry is added, deleted, or updated.
– a Link Layer Discovery Protocol (LLDP) cache entry is added, deleted or updated.
– an interface link status changes.
– an interface line status changes.
•
Identity—Identity event detector generates an event when AAA authorization and authentication is
successful, when failure occurs, or after normal user traffic on the port is allowed to flow.
•
Mac-Address-Table—Mac-Address-Table event detector generates an event when a MAC address is
learned in the MAC address table.
Note
The Mac-Address-Table event detector is supported only on switch platforms and can be used
only on Layer 2 interfaces where MAC addresses are learned. Layer 3 interfaces do not learn
addresses,and routers do not usually support the MAC address-table infrastructure needed to
notify EEM of a learned MAC address.
EEM 3.2 also introduces CLI commands to support the applets to work with the new event detectors.
For further details about EEM 3.2 features, see the Embedded Event Manager 3.2 document.
http://www.cisco.com/en/US/docs/ios/netmgmt/configuration/guide/nm_eem_3.2.html
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Configuring Embedded Event Manager
Configuring Embedded Event Manager
•
Registering and Defining an Embedded Event Manager Applet, page 34-6
•
Registering and Defining an Embedded Event Manager TCL Script, page 34-7
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.
Command
Purpose
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
Specify the event criteria that causes the EEM applet to run.
event snmp oid oid-value get-type
{exact | next} entry-op {gt | ge | eq | ne |
(Optional) Exit criteria. If exit criteria are not specified, event monitoring
lt | le} entry-val entry-val [exit-comb
is re-enabled immediately.
{or | and}] [exit-op {gt | ge | eq | ne | lt |
le}] [exit-val exit-val] [exit-time
exit-time-val] poll-interval poll-int-val
Step 4
action label syslog [priority
priority-level] msg msg-text
Step 5
end
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.
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
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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.
Command
Purpose
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
Step 3
event manager environment Configure the value of the specified EEM environment variable. Repeat this step for
variable-name string
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.
Enter global configuration mode.
This example shows the sample output for the show event manager environment command:
Switch# show event manager environment all
No. Name
Value
1
_cron_entry
0-59/2 0-23/1 * * 0-6
2
_show_cmd
show ver
3
_syslog_pattern
.*UPDOWN.*Ethernet1/0.*
4
_config_cmd1
interface Ethernet1/0
5
_config_cmd2
no shut
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 Network Management Command Reference.
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