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Embedded Event Manager Overview

Table Of Contents

Embedded Event Manager Overview

Contents

Information About Embedded Event Manager

Embedded Event Manager

Embedded Event Manager 1.0

Embedded Event Manager 2.0

Embedded Event Manager 2.1

Embedded Event Manager 2.1 (Software Modularity)

Embedded Event Manager 2.2

Embedded Event Manager 2.3

Embedded Event Manager 2.4

Embedded Event Manager 3.0

Embedded Event Manager 3.1

EEM Event Detectors Available by Cisco IOS Release

Event Detectors

EEM Actions Available by Cisco IOS Release

Embedded Event Manager Actions

Embedded Event Manager Environment Variables

Embedded Event Manager Policy Creation

Where to Go Next

Additional References

Related Documents

Standards

MIBs

RFCs

Technical Assistance

Feature Information for Embedded Event Manager Overview


Embedded Event Manager Overview


First Published: October 31, 2005
Last Update: Novemeber 20, 2009

Embedded Event Manager (EEM) is a distributed and customized approach to event detection and recovery offered directly in a Cisco IOS device. EEM offers the ability to monitor events and take informational, corrective, or any desired EEM action when the monitored events occur or when a threshold is reached. An EEM policy is an entity that defines an event and the actions to be taken when that event occurs.

This module contains a technical overview of EEM. EEM can be used alone, or with other network management technologies to help monitor and maintain your network. Before you begin to implement EEM, it is important that you understand the information presented in this module.

Finding Feature Information in This Module

Your Cisco IOS software release may not support all of the features documented in this module. To reach links to specific feature documentation in this module and to see a list of the releases in which each feature is supported, use the "Feature Information for Embedded Event Manager Overview" section.

Finding Support Information for Platforms and Cisco IOS and Catalyst OS Software Images

Use Cisco Feature Navigator to find information about platform support and Cisco IOS and Catalyst OS software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.

Contents

Information About Embedded Event Manager

Where to Go Next

Additional References

Feature Information for Embedded Event Manager Overview

Information About Embedded Event Manager

To use EEM in your network, you should understand the following concepts:

Embedded Event Manager

Embedded Event Manager 1.0

Embedded Event Manager 2.0

Embedded Event Manager 2.1

Embedded Event Manager 2.1 (Software Modularity)

Embedded Event Manager 2.2

Embedded Event Manager 2.3

Embedded Event Manager 2.4

Embedded Event Manager 3.0

Event Detectors

Embedded Event Manager Actions

Embedded Event Manager Environment Variables

Embedded Event Manager Policy Creation

Embedded Event Manager

Event tracking and management has traditionally been performed by devices external to the networking device. Embedded Event Manager (EEM) has been designed to offer event management capability directly in Cisco IOS devices. The on-device, proactive event management capabilities of EEM are useful because not all event management can be done off router because some problems compromise communication between the router and the external network management device. Capturing the state of the router during such situations can be invaluable in taking immediate recovery actions and gathering information to perform root-cause analysis. Network availability is also improved if automatic recovery actions are performed without the need to fully reboot the routing device.

EEM is a flexible, policy-driven framework that supports in-box monitoring of different components of the system with the help of software agents known as event detectors. Figure 1 shows the relationship between the EEM server, core event publishers (event detectors), and the event subscribers (policies). Basically, 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 of interest occurs. The EEM policies that are configured using the Cisco IOS command-line interface (CLI) then implement recovery on the basis of the current state of the system and the actions specified in the policy for the given event.

EEM offers the ability to monitor events and take informational or corrective action when the monitored events occur or when 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).

Figure 1 Embedded Event Manager Core Event Detectors

Embedded Event Manager 1.0

EEM 1.0 is supported in Cisco IOS Releases 12.0(26)S and 12.3(4)T and later releases and introduced Embedded Event Manager. EEM 1.0 introduced the following event detectors:

SNMP—The Simple Network Management Protocol (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—The syslog event detector allows for screening syslog messages for a regular expression pattern match.

EEM 1.0 introduced the following actions:

Generating prioritized syslog messages.

Generating a Cisco Networking Services (CNS) event for upstream processing by CNS devices.

Reloading the Cisco IOS software.

Switching to a secondary processor in a fully redundant hardware configuration.

Embedded Event Manager 2.0

EEM 2.0 is supported in Cisco IOS Release 12.2(25)S and later releases and introduced some new features. EEM 2.0 introduced the following event detectors:

Application-Specific—The application-specific event detector allows any Embedded Event Manager policy to publish an event.

Counter—The counter event detector publishes an event when a named counter crosses a specified threshold.

Interface Counter—The interface counter event detector publishes an event when a generic Cisco IOS interface counter for a specified interface crosses a defined threshold.

Timer—The timer event detector publishes events for the following four different types of timers: absolute-time-of-day, countdown, watchdog, and CRON.

Watchdog System Monitor (IOSWDSysMon)—The Cisco IOS watchdog system monitor event detector publishes an event when CPU or memory utilization for a Cisco IOS process crosses a threshold.

EEM 2.0 introduced the following actions:

Setting or modifying a named counter.

Publishing an application-specific event

Generating an SNMP trap.

The ability to run a Cisco defined sample policy written using Tool Command Language (Tcl) was introduced. A sample policy was provided that could be stored in the system policy directory.

Embedded Event Manager 2.1

EEM 2.1 is supported in Cisco IOS Release 12.3(14)T, 12.2(18)SXF5, 12.2(28)SB, 12.2(33)SRA, and later releases, and introduced some new features. EEM 2.1 introduced the following new event detectors:

CLI—The CLI event detector screens command-line interface (CLI) commands for a regular expression match.

None—The none event detector publishes an event when the Cisco IOS event manager run command executes an EEM policy.

OIR—The online insertion and removal (OIR) event detector publishes an event when a particular hardware insertion or removal event occurs.

EEM 2.1 introduced the following actions:

Executing a Cisco IOS CLI command.

Requesting system information when an event occurs.

Sending a short e-mail.

Manually running an EEM policy.

EEM 2.1 also permits multiple concurrent policies to be run using the new event manager scheduler script command. Support for SNMP event detector rate-based events is provided as is the ability to create policies using Tool Command Language (Tcl).

Embedded Event Manager 2.1 (Software Modularity)

EEM 2.1 (Software Modularity) is supported in Cisco IOS Release 12.2(18)SXF4 and later releases on Cisco IOS Software Modularity images. EEM 2.1 (Software Modularity) introduced the following event detectors:

GOLD—The Generic Online Diagnostic (GOLD) event detector publishes an event when a GOLD failure event is detected on a specified card and subcard.

System Manager—The system manager event detector generates events for Cisco IOS Software Modularity process start, normal or abnormal stop, and restart events. The events generated by the system manager allows policies to change the default behavior of the process restart.

Watchdog System Monitor (WDSysMon)—The Cisco IOS Software Modularity watchdog system monitor event detector detects infinite loops, deadlocks, and memory leaks in Cisco IOS Software Modularity processes.

EEM 2.1 for Software Modularity introduced the ability to display EEM reliability metric data for processes.


Note EEM 2.1 for Software Modularity images also supports the resource and RF event detectors introduced in EEM 2.2, but it does not support the enhanced object tracking event detector or the actions to read and set tracked objects.


Embedded Event Manager 2.2

EEM 2.2 is supported in Cisco IOS Release 12.4(2)T, 12.2(31)SB3, 12.2(33)SRB, and later releases, and introduced some new features. EEM 2.2 introduced the following event detectors:

Enhanced Object Tracking—The enhanced object tracking event detector publishes an event when the tracked object changes. Enhanced object tracking provides complete separation between the objects to be tracked and the action to be taken by a client when a tracked object changes.

Resource—The resource event detector publishes an event when the Embedded Resource Manager (ERM) reports an event for the specified policy.

RF—The redundancy framework (RF) event detector publishes an event when one or more RF events occur during synchronization in a dual Route Processor (RP) system. The RF event detector can also detect an event when a dual RP system continuously switches from one RP to another RP (referred to as a ping-pong situation).

EEM 2.2 introduced the following actions:

Reading the state of a tracked object.

Setting the state of a tracked object.

Embedded Event Manager 2.3

EEM 2.3 is supported in Cisco IOS Release 12.2(33)SXH and later releases for the Cisco Catalyst 6500 Series switches and introduces enhancements to the Generic Online Diagnostics (GOLD) Event Detector on that product.

The event gold command was enhanced with the addition of the action-notify, testing-type, test-name, test-id, consecutive-failure, platform-action, and maxrun keywords for improved reaction to GOLD test failures and conditions.

The following platform-wide GOLD Event Detector information can be accessed through new read-only EEM built-in environment variables:

Boot-up diagnostic level

Card index, name, serial number

Port counts

Test counts

The following test-specific GOLD Event Detector information can be accessed through new read-only EEM built-in environment variables (available to EEM applets only):

Test name, attribute, total run count

Test result per test, port, or device

Total failure count, last fail time

Error code

Occurrence of consecutive failures

These enhancements result in reduced mean time to recovery (MTTR) and higher availability through improved automation and fault detection.

Embedded Event Manager 2.4

EEM 2.4 is supported in Cisco IOS Release 12.4(20)T, 12.2(33)SXI, 12.2(33)SRE and later releases, and introduced several new features. EEM 2.4 introduced the following event detectors:

SNMP Notification—The SNMP notification event detector provides the ability to intercept SNMP trap and inform messages coming into the router. An SNMP notification event is generated when an incoming SNMP trap or inform message matches specified values or crosses specified thresholds.

RPC—The remote procedure call (RPC) event detector provides the ability to invoke EEM policies from outside the router over an encrypted connection using Secure Shell (SSH). The RPC event detector uses Simple Object Access Protocol (SOAP) data encoding for exchanging XML-based messages. This event detector can be used to run EEM policies and then receive output in a SOAP XML-formatted reply.

EEM 2.4 added enhancements to the following event detectors:

Interface counter rate-based trigger—This feature adds the ability for an interface event to be triggered based on a rate of change over a period of time. A rate can be specified both for the entry value and the exit value. This feature copies the rate-based functionality that currently exists for the SNMP event detector.

SNMP delta value—The difference between the monitored Object Identifier (OID) value at the beginning of the monitored period and the actual OID value when the event is published will be provided in the event_reqinfo data for both the SNMP event detector and the Interface Counter event detector.

EEM 2.4 introduced the following actions:

Multiple event support—The ability to run multiple events was introduced. and show event manager commands were enhanced to show multiple events.

Support for parameters—The parameter argument has been added to the event manager run command. A maximum of 15 parameters can be used.

Display of Job IDs and completion status—Some of the show event manager commands were enhanced to display Job IDs and completion status.

Bytecode support—Tcl 8 defines a specialized bytecode language (BCL) and includes a just-in-time compiler that translates Tcl scripts to BCL. Byte sequence is executed by a "virtual machine," Tcl_ExecuteByteCode(), or TEBC for short, as often as needed. Currently EEM accepts file extensions, such as *.tcl for user policies and *.tm for system policies. Tcl standard extension for bytecode scripts are *.tbc. Now EEM will accept *.tbc as valid EEM policies.

Registration substitution enhancement—Supports replacing multiple parameters in the event registration statement lines with a single environment variable.

Tcl package support

Embedded Event Manager 3.0

EEM 3.0 is supported in Cisco IOS Release 12.4(22)T, 12.2(33)SRE, and later releases.

EEM 3.0 introduces the following new event detectors:

Custom CLI—The custom CLI event detector publishes an event to add and enhance existing CLI command syntax.

Routing—The Routing event detector publishes an event when route entries change in the Routing Information Base (RIB).

NetFlow— The NetFlow event detector publishes an event when a NetFlow event is triggered.

IP SLA—The IP SLA event detector publishes an event when an IP SLA reaction is triggered.

EEM 3.0 introduces the following features.

Class-based scheduling—The EEM policies will be assigned a class using the class keyword when they are registered. EEM policies registered without a class will be assigned to the default class.

High performance Tcl policies—Three new Tcl commands are introduced event_completion, event_wait, and event_completion_with_wait.

Interactive cli support—The synchronous applets are enhanced to support interaction with the local console (TTY). Two new IOS commands, action gets and action puts, are introduced to allow users to enter and display input directly on the console.

Variable logic for applets—The Variable Logic for EEM Applets feature adds the ability to apply conditional logic within EEM applets. Conditional logic introduces a control structure that can change the flow of actions within applets depending on conditional expressions.

Digital signature support—A new API performs digital signature verification for a Tcl script to check it the script is signed by Cisco before execution.

Support authenticating e-mail servers—The action mail command is modified to include an optional username and password.

SMTP IPv6 support—The keyword sourceaddr is added in Tcl e-mail templates to specify either an IPv6 or IPv4 address.

SNMP library extensions—The EEM applet action info and Tcl sys_reqinfo_snmp commands are enhanced to include functionality for SNMP getid, inform, trap, and set-type operations.

SNMP Notification IPv6 support—IPv6 address is supported for the source and destination IP addresses.

CLI Library XML-PI support—Provides a programmable interface which encapsulates IOS command-line interface (CLI) show commands in XML format in a consistent way across different Cisco products. Customers using XML-PI will be able to parse IOS show command output from within Tcl scripts using well-known keywords instead of having to depend on the use of regular expression support.

Embedded Event Manager 3.1

EEM 3.1 is supported in Cisco IOS Release 15.0(1)M and later releases, and introduces sthe following:

EEM 3.1 introduced one new event detector:

SNMP Object—The Simple Network Management Protocol (SNMP) object trap event detector provides an extension to replace the value when an SNMP trap with the specified SNMP object ID (OID) is encountered on a specific interface or address.

EEM 3.1 added an enhancement to the following event detector:

SNMP Notification—The SNMP notification event detector now can wait and intercept the outgoing SNMP traps and informs.

EEM 3.1 added enhancement to the following action:

Specify facility—The action syslog command has been enhanced to specify syslog facility.

EEM 3.1 introduces the following features:

Provides the ability to create a short description for the registered policy—A new description command has been introduced to register policies with a brief description in Cisco IOS CLI and Tcl policies. The show event manager policy available command and the show event manager policy registered command have been enhanced to add the description keyword to display the description of the registered applet.

Enables EEM policies to bypass AAA authorization—The event manager application command has been enhanced to provide authorization and bypass keywords to disable AAA.

Introduces CLI Library enhancements—Provides two new commands in the CLI library: cli_run and cli_run_interactive.

EEM Event Detectors Available by Cisco IOS Release

EEM uses software programs known as event detectors to determine when an EEM event occurs. Some event detectors are available on every Cisco IOS release, but most event detectors have been introduced in a specific release. Use Table 1 to determine which event detectors are available in your specific Cisco IOS release. A blank entry (—) indicates that the event detector is not available: the text "Yes" indicates that the event detector is available. The event detectors shown in Table 1 are supported in later releases of the same Cisco IOS release train. For more details on each event detector, see the Event Detectors concept in the "Embedded Event Manager Overview" module.

Table 1 Availability of Event Detectors by Cisco IOS Release 

Event Detector
12.2(25)S
12.3(14)T 12.2(18)SXF5
12.2(28)SB
12.2(33)SRA
12.4(2)T
12.2(31)SB3
12.2(33)SRB
12.2(18)SXF4
Cisco IOS Software Modularity
12.2(33)SXH
12.4(20)T
12.2(33)SXI
12.4(22)T
12.2(33)SRE
15.0(1)M

Application-Specific

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

CLI

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Counter

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Custom CLI

Yes

Yes

Enhanced Object Tracking

Yes

Yes

Yes

Yes

Yes

GOLD

Yes

Yes

Yes

Yes

Yes

Interface Counter

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

IPSLA

Yes

Yes

NF

Yes

Yes

None

Yes

Yes

Yes

Yes

Yes

Yes

Yes

OIR

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Resource

Yes

Yes

Yes

Yes

Yes

Yes

RF

Yes

Yes

Yes

Yes

Yes

Yes

Routing

Yes

Yes

RPC

Yes

Yes

Yes

SNMP

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

SNMP Notification

Yes

Yes

Yes

SNMP Object

Yes

Syslog

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

System Manager

Yes

Yes

Yes

Yes

Yes

Timer

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

IOSWDSysMon (Cisco IOS watchdog)

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

WDSysMon (Cisco IOS Software Modularity watchdog)

Yes

 

Event Detectors

Embedded Event Manager (EEM) uses software programs known as event detectors to determine when an EEM event occurs. Event detectors are separate systems that provide an interface between the agent being monitored, for example Simple Network Management Protocol (SNMP), and the EEM policies where an action can be implemented. Some event detectors are available on every Cisco IOS release, but most event detectors have been introduced in a specific release. For details of which event detector is supported in each Cisco IOS release, see the EEM Event Detectors Available by Cisco IOS Release concept in the "Writing Embedded Event Manager Policies Using the Cisco IOS CLI" or the "Writing Embedded Event Manager Policies Using Tcl" modules. EEM contains the following event detectors.

Application-Specific Event Detector

The application-specific event detector allows any Embedded Event Manager policy to publish an event. When an EEM policy publishes an event it must use an EEM subsystem number of 798 with any event type. If an existing policy is registered for subsystem 798 and a specified event type, a second policy of the same event type will trigger the first policy to run when the specified event is published.

CLI Event Detector

The CLI event detector screens command-line interface (CLI) commands for a regular expression match. When a match is found, an event is published. The match logic is performed on the fully expanded CLI command after the command is successfully parsed and before it is executed. The CLI event detector supports three publish modes:

Synchronous publishing of CLI events—The CLI command is not executed until the EEM policy exits, and the EEM policy can control whether the command is executed. The read/write variable, _exit_status, allows you to set the exit status at policy exit for policies triggered from synchronous events. If _exit_status is 0, the command is skipped, if _exit_status is 1, the command is run.

Asynchronous publishing of CLI events—The CLI event is published, and then the CLI command is executed.

Asynchronous publishing of CLI events with command skipping—The CLI event is published, but the CLI command is not executed.

Counter Event Detector

The counter event detector publishes an event when a named counter crosses a specified threshold. There are two or more participants that affect counter processing. The counter event detector can modify the counter, and one or more subscribers define the criteria that cause the event to be published. After a counter event has been published, the counter monitoring logic can be reset to start monitoring the counter immediately or it can be reset when a second threshold—called an exit value—is crossed.

Custom CLI Event Detector

The custom CLI event detector publishes an event to add and enhance existing CLI command syntax. When the special parser characters Tab, ? (question mark), and Enter are entered, the parser sends the input to the custom CLI event detector for processing. The custom CLI event detector then compares this input against registered strings to determine if this is a new or enhanced CLI command. Upon a match the custom CLI event detector takes appropriate actions, such as displaying help for the command if ? is entered, displaying the entire command if Tab is entered, or executing the command if Enter was entered. If a match does not occur, the parser regains control and processes the information as usual.

Enhanced Object Tracking Event Detector

The enhanced object tracking (EOT) event detector publishes an event when the status of a tracked object changes. Object tracking was first introduced into the Hot Standby Router Protocol (HSRP) as a simple tracking mechanism that allowed you to track the interface line-protocol state only. If the line-protocol state of the interface went down, the HSRP priority of the router was reduced, allowing another HSRP router with a higher priority to become active.

Object tracking was enhanced to provide complete separation between the objects to be tracked and the action to be taken by a client when a tracked object changes. Thus, several clients such as HSRP, VRRP, or GLBP can register their interest with the tracking process, track the same object, and each take different action when the object changes. Each tracked object is identified by a unique number that is specified on the tracking command-line interface (CLI). Client processes use this number to track a specific object. The tracking process periodically polls the tracked objects and notes any change of value. The changes in the tracked object are communicated to interested client processes, either immediately or after a specified delay. The object values are reported as either up or down.

Enhanced object tracking is now integrated with EEM to allow EEM to report on a status change of a tracked object and to allow enhanced object tracking to track EEM objects. A new type of tracking object—a stub object—is created. The stub object can be manipulated using the existing CLI commands that already allow tracked objects to be manipulated.

GOLD Event Detector

The GOLD event detector publishes an event when a GOLD failure event is detected on a specified card and subcard.

Interface Counter Event Detector

The 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. If the incremental value is set to 50, for example, an event would be published when the interface counter increases by 50.

After an interface counter event has been published, the interface counter monitoring logic is reset using two methods. The interface counter is reset either when a second threshold—called an exit value—is crossed or when an elapsed period of time occurs.

IP SLA Event Detector

The IP SLA event detector publishes an event when an IP SLA reaction is triggered.

NetFlow Event Detector

The NetFlow event detector publishes an event when a NetFlow event is triggered.

None Event Detector

The none event detector publishes an event when the Cisco IOS event manager run CLI command executes an EEM policy. EEM schedules and runs policies on the basis of an event specification that is contained within the policy itself. An EEM policy must be identified and registered to be permitted to run manually before the event manager run command will execute.

OIR Event Detector

The online insertion and removal (OIR) event detector publishes an event when one of the following hardware insertion or removal events occurs:

A card is removed.

A card is inserted.

Route Processors (RPs), line cards, or feature cards can be monitored for OIR events.

Resource Event Detector

The resource event detector publishes an event when the Embedded Resource Manager (ERM) reports an event for the specified policy. The ERM infrastructure tracks resource depletion and resource dependencies across processes and within a system to handle various error conditions. The error conditions are handled by providing an equitable sharing of resources between various applications. The ERM framework provides a communication mechanism for resource entities and allows communication between these resource entities from numerous locations. The ERM framework also helps in debugging CPU and memory-related issues. The ERM monitors system resource usage to better understand scalability needs by allowing you to configure threshold values for resources such as the CPU, buffers, and memory. The ERM event detector is the preferred method for monitoring resources in Cisco IOS software but the ERM event detector is not supported in Software Modularity images. For more details about ERM, go to "Embedded Resource Manager" module.

RF Event Detector

The redundancy framework (RF) event detector publishes an event when one or more RF events occur during synchronization in a dual Route Processor (RP) system. The RF event detector can also detect an event when a dual RP system continuously switches from one RP to another RP (referred to as a ping-pong situation).

RPC Event Detector

The remote procedure call (RPC) event detector provides the ability to invoke EEM policies from outside the router over an encrypted connection using Secure Shell (SSH). The RPC event detector uses Simple Object Access Protocol (SOAP) data encoding for exchanging XML-based messages. This event detector can be used to run EEM policies and then receive output in a SOAP XML-formatted reply.

Routing Event Detector

The routing event detector publishes an event when a route entry changes in the Routing Information Base (RIB).

SNMP Event Detector

The 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.

SNMP Notification Event Detector

The SNMP notification event detector provides the ability to intercept SNMP trap and inform messages coming into or going out of the router. An SNMP notification event is generated when an incoming or outgoing SNMP trap or inform message matches specified values or crosses specified thresholds. The SNMP event detector can wait and intercept the outgoing SNMP traps and informs.

SNMP Object Event Detector

The Simple Network Management Protocol (SNMP) object trap event detector provides an extension to replace the value when an SNMP trap with the specified SNMP object ID (OID) is encountered on a specific interface or address.

Syslog Event Detector

The 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.

System Manager Event Detector

The system manager event detector generates events for Cisco IOS Software Modularity process start, normal or abnormal stop, and restart events. The events generated by the system manager allows policies to change the default behavior of the process restart.

Timer Event Detector

The timer event detector publishes events for the following four different types of 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 and then the timer automatically resets itself to its initial value and starts to count down again.

A CRON timer publishes an event using a UNIX standard CRON specification to indicate when the event is to be published. A CRON timer never publishes events more than once per minute.

Watchdog System Monitor (IOSWDSysMon) Event Detector for Cisco IOS

The Cisco IOS watchdog system monitor event detector publishes an event when one of the following occurs:

CPU utilization for a Cisco IOS task crosses a threshold.

Memory utilization for a Cisco IOS task crosses a threshold.


Note Cisco IOS processes are now referred to as tasks to distinguish them from Cisco IOS Software Modularity processes.


Two events may be monitored at the same time, and the event publishing criteria can be specified to require one event or both events to cross their specified thresholds.

Watchdog System Monitor (WDSysMon) Event Detector for Cisco IOS Software Modularity

The Cisco IOS Software Modularity watchdog system monitor event detector detects infinite loops, deadlocks, and memory leaks in Cisco IOS Software Modularity processes.

EEM Actions Available by Cisco IOS Release

The CLI-based corrective actions that are taken when event detectors report events enable a powerful on-device event management mechanism. Some actions are available in every Cisco IOS release, but most actions have been introduced in a specific release. Use Table 2 to determine which actions are available in your specific Cisco IOS release. A blank entry (—) indicates that the action is not available; the text "Yes" indicates that the action is available. The actions shown in Table 2 are supported in later releases of the same Cisco IOS release train. For more details on each action, see the Embedded Event Manager Actions concept in the "Embedded Event Manager Overview" module.

Table 2 Availability of Actions by Cisco IOS Release 

Action
12.2(25)S
12.3(14)T 12.2(18)SXF5
12.2(28)SB
12.2(33)SRA
12.4(2)T
12.2(31)SB3
12.2(33)SRB
12.2(18)SXF4
Cisco IOS Software Modularity
12.2(33)SXH
12.4(20)T
12.4(22)T
15.0(1)M

Execute a CLI command

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Generate a CNS event

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Generate a prioritized syslog message

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Generate an SNMP trap

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Manually run an EEM policy

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Publish an application-specific event

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Read the state of a tracked object

Yes

 

Yes

Yes

Yes

Reload the Cisco IOS software

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Request system information

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Send a short e-mail

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Set or modify a named counter

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Set the state of a tracked object

Yes

 

Yes

Yes

Yes

Switch to a secondary RP

Yes

Yes

Yes

Yes

Yes

Yes

Yes

Yes


Embedded Event Manager Actions

The CLI-based corrective actions that are taken when event detectors report events enable a powerful on-device event management mechanism. Some EEM actions are available on every Cisco IOS release, but most EEM actions have been introduced in a specific release. For details of which EEM action is supported in each Cisco IOS release, see the EEM Actions Available by Cisco IOS Release concept in the "Writing Embedded Event Manager Policies Using the Cisco IOS CLI" or the "Writing Embedded Event Manager Policies Using Tcl" modules. EEM supports the following actions:

Executing a Cisco IOS command-line interface (CLI) command.

Generating a CNS event for upstream processing by Cisco CNS devices.

Setting or modifying a named counter.

Switching to a secondary processor in a fully redundant hardware configuration.

Requesting system information when an event occurs.

Sending a short e-mail.

Manually running an EEM policy.

Publishing an application-specific event.

Reloading the Cisco IOS software.

Generating an SNMP trap.

Generating prioritized syslog messages.

Reading the state of a tracked object.

Setting the state of a tracked object.

EEM action CLI commands contain an EEM action label that is a unique identifier that can be any string value. Actions are sorted and run in ascending alphanumeric (lexicographical) key sequence using the label as the sort key. If you are using numbers as labels be aware that alphanumerical sorting will sort 10.0 after 1.0, but before 2.0, and in this situation we recommend that you use numbers such as 01.0, 02.0, and so on, or use an initial letter followed by numbers.

Embedded Event Manager Environment Variables

EEM allows environment variables to be used in EEM policies. Tool Command Language (Tcl) allows global variables to be defined that are known to all procedures within a Tcl script. EEM allows environment variables to be defined using a CLI command, the event manager environment command, for use within an EEM policy. All EEM environment variables are automatically assigned to Tcl global variables before a Tcl script is run. There are three different types of environment variables associated with Embedded Event Manager:

User-defined—Defined by you if you create an environment variable in a policy that you have written.

Cisco-defined—Defined by Cisco for a specific sample policy.

Cisco built-in (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 at policy exit for policies triggered from synchronous events.

Cisco-defined environment variables (see Table 3) and Cisco system-defined environment variables may 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 using the event manager environment command. Variables that are used in the EEM policy must be defined before you register the policy. A Tcl policy contains a section called "Environment Must Define" that can be defined to check that any required environment variables are defined before the policy runs.

Cisco built-in environment variables are a subset of the Cisco-defined environment variables and the built-in variables are available to EEM applets only. The built-in variables can be read-only or can be read and write, and these variables may apply to one specific event detector or to all event detectors. For more details and a table listing the Cisco system-defined variables, see the ""Writing Embedded Event Manager Policies Using the Cisco IOS CLI" module.


Note Cisco-defined environment variables begin with an underscore character (_). We strongly recommend that customers avoid the same naming convention to prevent naming conflicts.


Table 3 describes the Cisco-defined variables used in the sample EEM policies. Some of the environment variables do not have to be specified for the corresponding sample policy to run and these are marked as optional.

Table 3 Cisco-Defined Environmental Variables and Examples 

Environment Variable
Description
Example

_config_cmd1

The first configuration command that is executed.

interface Ethernet1/0

_config_cmd2

(Optional) The second configuration command that is executed.

no shutdown

_crash_reporter_debug

(Optional) A value that identifies whether debug information for tm_crash_reporter.tcl will be enabled.

1

_crash_reporter_url

The URL location to which the crash report is sent.

http://www.yourdomain.com/
fm/interface_tm.cgi

_cron_entry

A CRON specification that determines when the policy will run. See the "Writing Embedded Event Manager Policies Using Tcl" module for more information about how to specify a cron entry.

0-59/1 0-23/1 * * 0-7

_email_server

A Simple Mail Transfer Protocol (SMTP) mail server used to send e-mail.

mailserver.yourdomain.com

_email_to

The address to which e-mail is sent.

engineer@yourdomain.com

_email_from

The address from which e-mail is sent.

devtest@yourdomain.com

_email_cc

The address to which the e-mail is be copied.

manager@yourdomain.com

_email_ipaddr

The source IP address of the recipient.

209.165.201.1 or
(IPv6 address) 2001:0DB8::1

_info_snmp_oid

The SNMP object ID.

1.3.6.1.2.1.2 or iso.internet.mgmt.mib-2.interfaces

_info_snmp_value

The value string of the associated SNMP data element.

 

_show_cmd

The CLI show command to be executed when the policy is run.

show version

_syslog_pattern

A regular expression pattern match string that is used to compare syslog messages to determine when the policy runs.

.*UPDOWN.*FastEthernet
0/0.*

_tm_fsys_usage_cron

(Optional) A CRON specification that is used in the event_register keyword extension. If unspecified, the _tm_fsys_usage.tcl policy is triggered once per minute.

0-59/1 0-23/1 * * 0-7

_tm_fsys_usage_debug

(Optional) When this variable is set to a value of 1, disk usage information is displayed for all entries in the system.

1

_tm_fsys_usage_
freebytes

(Optional) Free byte threshold for systems or specific prefixes. If free space falls below a given value, a warning is displayed.

disk2:98000000

_tm_fsys_usage_percent

(Optional) Disk usage percentage thresholds for systems or specific prefixes. If disk usage percentage exceeds a given percentage, a warning is displayed. If unspecified, the default disk usage percentage is 80 percent for all systems.

nvram:25 disk2:5


Embedded Event Manager Policy Creation

EEM is a policy driven process in which the EEM policy engine receives notifications when faults and other events occur in the Cisco IOS software system. Embedded Event Manager policies implement recovery based on the current state of the system and the actions specified in the policy for a given event. Recovery actions are triggered when the policy is run.

Although there are some EEM CLI configuration and show commands, EEM is implemented through the creation of policies. 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 Tcl.

The creation of an EEM policy involves:

Selecting the event for which the policy is run.

Defining the event detector options associated with logging and responding to the event.

Defining the environment variables, if required.

Choosing the actions to be performed when the event occurs.

There are two ways to create an EEM policy. The first method is to write applets using CLI commands, and the second method is to write Tcl scripts. Cisco provides enhancements to Tcl in the form of Tcl command extensions that facilitate the development of EEM policies. Scripts are defined off the networking device using an ASCII editor. The script is then copied to the networking device and registered with EEM. When a policy is registered with the Embedded Event Manager, the software examines the policy and registers it to be run when the specified event occurs. Policies can be unregistered or suspended. Both types of policies can be used to implement EEM in your network.

For details on writing EEM policies using the Cisco IOS CLI, go to "Writing Embedded Event Manager Policies Using the Cisco IOS CLI" module.

For details on writing EEM policies using Tcl, go to "Writing Embedded Event Manager Policies Using Tcl" module.

Where to Go Next

If you want to write EEM policies using the Cisco IOS CLI, see the "Writing Embedded Event Manager Policies Using the Cisco IOS CLI" module.

If you want to write EEM policies using Tcl, see the "Writing Embedded Event Manager Policies Using Tcl" module.

Additional References

The following sections provide references related to EEM.

Related Documents

Related Topic
Document Title

Cisco IOS commands

Cisco IOS Master Commands List, All Releases

Network Management commands (including EEM commands): complete command syntax, defaults, command mode, command history, usage guidelines, and examples

Cisco IOS Network Management Command Reference

Embedded Event Manager policy writing using the CLI

Writing Embedded Event Manager Policies Using the Cisco IOS CLI module

Embedded Event Manager policy writing using Tcl

Writing Embedded Event Manager Policies Using Tcl module

Embedded Resource Manager

Embedded Resource Manager module


Standards

Standard
Title

No new or modified standards are supported, and support for existing standards has not been modified.


MIBs

MIB
MIBs Link

CISCO-EMBEDDED-EVENT-MGR-MIB

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs


RFCs

RFC
Title

No new or modified RFCs are supported, and support for existing RFCs has not been modified.


Technical Assistance

Description
Link

The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies.

To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds.

Access to most tools on the Cisco Support website requires a Cisco.com user ID and password.

http://www.cisco.com/cisco/web/support/index.html


Feature Information for Embedded Event Manager Overview

Table 4 lists the features in this module and provides links to specific configuration information. Only features that were introduced or modified in Cisco IOS Releases 12.3(14)T, 12.2(25)S, 12.0(26)S, 12.2(18)SXF4, 12.2(28)SB, 12.2(33)SRA, 12.2(33)SXH, 12.2(33)SXI, 12.4(20)T, 12.4(22)T, 15.0(1)M, 12.2(33)SRE or a later release appear in the table.

Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.

Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS and Catalyst OS software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.


Note Table 4 lists only the Cisco IOS software release that introduced support for a given feature in a given Cisco IOS software release train. Unless noted otherwise, subsequent releases of that Cisco IOS software release train also support that feature.


Table 4 Feature Information for Embedded Event Manager Overview 

Feature Name
Releases
Feature Configuration Information

Embedded Event Manager 1.0

12.0(26)S
12.3(4)T

EEM 1.0 introduced Embedded Event Manager applet creation with the SNMP and Syslog event detectors. EEM 1.0 also introduced the following actions: generating prioritized syslog messages, generating a CNS event for upstream processing by Cisco CNS devices, reloading the Cisco IOS software, and switching to a secondary processor in a fully redundant hardware configuration.

The following sections provide information about this feature:

Embedded Event Manager 1.0

Event Detectors

Embedded Event Manager Actions

Embedded Event Manager Policy Creation

The following commands were introduced by this feature: action cns-event, action force-switchover, action reload, action syslog, debug event manager, event manager applet, event snmp, event syslog, show event manager policy registered.

Embedded Event Manager 2.0

12.2(25)S

EEM 2.0 introduced the application-specific event detector, the counter event detector, the interface counter event detector, the timer event detector, and the IOSWDSysMon event detector. New actions include setting and modifying a named counter, publishing an application-specific event, and generating an SNMP trap. The ability to define environment variables and to run a sample EEM policy (included in the software) written using Tcl was introduced.

The following sections provide information about this feature:

Embedded Event Manager 2.0

Event Detectors

Embedded Event Manager Actions

Embedded Event Manager Environment Variables

Embedded Event Manager Policy Creation

The following commands were introduced by this feature: action counter, action publish-event, action snmp-trap, event application, event counter, event interface, event ioswdsysmon, event manager environment, event manager history size, event manager policy, event manager scheduler suspend, event timer, show event manager environment, show event manager history events, show event manager history traps, show event manager policy available, show event manager policy pending.

Embedded Event Manager 2.1

12.3(14)T 12.2(18)SXF5
12.2(28)SB
12.2(33)SRA

EEM 2.1 introduced some new event detectors and actions with new functionality to allow EEM policies to be run manually and the ability to run multiple concurrent policies. Support for Simple Network Management Protocol (SNMP) event detector rate-based events was provided as was the ability to create policies using Tool Command Language (Tcl).

The following sections provide information about this feature:

Embedded Event Manager 2.1

Event Detectors

Embedded Event Manager Actions

Embedded Event Manager Environment Variables

Embedded Event Manager Policy Creation

The following commands were introduced or modified by this feature: action cli, action counter, action info, action mail, action policy, debug event manager, event cli, event manager directory user, event manager policy, event manager run, event manager scheduler script, event manager session cli username, event none, event oir, event snmp, event syslog, set (EEM), show event manager directory user, show event manager policy registered, show event manager session cli username.

Embedded Event Manager 2.1 (Software Modularity)

12.2(18)SXF4
Cisco IOS Software Modularity images

EEM 2.1 for Software Modularity images introduced the GOLD, system manager, and WDSysMon (Cisco IOS Software Modularity watchdog) event detectors, and the ability to display Cisco IOS Software Modularity processes and process metrics.

The following sections provide information about this feature:

Embedded Event Manager 2.1 (Software Modularity)

Event Detectors

Embedded Event Manager Actions

Embedded Event Manager Environment Variables

Embedded Event Manager Policy Creation

The following commands were introduced by this feature: event gold, event process, show event manager metric process.

Note EEM 2.1 for Software Modularity images also supports the resource and RF event detectors introduced in EEM 2.2, but it does not support the enhanced object tracking event detector or the actions to read and set tracked objects.

Embedded Event Manager 2.2

12.4(2)T
12.2(31)SB3
12.2(33)SRB

EEM 2.2 introduced the enhanced object tracking, resource, and RF event detectors. The actions of reading and setting the state of a tracked object were also introduced.

The following sections provide information about this feature:

Embedded Event Manager 2.2

Event Detectors

Embedded Event Manager Actions

Embedded Event Manager Environment Variables

Embedded Event Manager Policy Creation

The following commands were introduced or modified by this feature: action track read, action track set, default-state, event resource, event rf, event track, show track, track stub-object.

Embedded Event Manager 2.3

12.2(33)SXH
12.2(33)SB

EEM 2.3 is supported in Cisco IOS Release 12.2(33)SXH and later releases for the Cisco Catalyst 6500 Series switches and introduces enhancements to the Generic Online Diagnostics (GOLD) Event Detector on that product.

The following sections provide information about this feature:

Embedded Event Manager 2.3

Event Detectors

Embedded Event Manager Actions

Embedded Event Manager Environment Variables

Embedded Event Manager Policy Creation

The event gold command was enhanced in addition to the Tcl keywords—action-notify, testing-type, test-name, test-id, consecutive-failure, platform-action, and maxrun—for improved reaction to GOLD test failures and conditions.

Embedded Event Manager 2.4

12.4(20)T
12.2(33)SXI
2.2(33)SRE

EEM 2.4 is supported in Cisco IOS Release 12.4(20)T and later releases, and introduced several new features.

The following sections provide information about this feature:

Embedded Event Manager 2.4

Event Detectors

Embedded Event Manager Actions

Embedded Event Manager Environment Variables

Embedded Event Manager Policy Creation

The following commands were introduced by this feature:

attribute (EEM), correlate, event manager detector rpc, event manager directory user repository, event manager update user policy, event manager scheduler clear, event manager update user policy, event owner, event rpc, event snmp-notification, show event manager detector, show event manager version, trigger (EEM).

Embedded Event Manger 3.0

12.4(22)T
12,2(33)SRE

EEM 3.0 is supported in Cisco IOS Release 12.4(22)T and later releases, and introduced several new features.

The following sections provide information about this feature:

Embedded Event Manager 3.0

Event Detectors

Embedded Event Manager Actions

Embedded Event Manager Environment Variables

Embedded Event Manager Policy Creation

The following commands were introduced or modified by this feature:

action add, action append, action break, action comment, action context retrieve, action context save, action continue, action decrement, action divide, action else, action elseif, action end, action exit, action foreach, action gets, action if, action if goto, action increment, action info type interface-names, action info type snmp getid, action info type snmp inform, action info type snmp oid, action info type snmp trap, action info type snmp var, action multiply, action puts, action regexp, action set (EEM), action string compare, action string equal, action string first, action string index, action string last, action string length, action string match, action string range, action string replace, action string tolower, action string toupper, action string trim, action string trimleft, action string trimright, action subtract, action while, event cli, event ipsla, event manager detector routing, event manager scheduler, event manager scheduler clear, event manager scheduler hold, event manager scheduler modify, event manager scheduler release, event nf, event routing, show event manager policy active, show event manager policy pending, and show event manager scheduler.

Embedded Event Manager 3.1

15.0(1)M

EEM 3.1 is supported in Cisco IOS Release 15.0(1)M and later releases, and introduced several new features.

The following sections provide information about this feature:

Embedded Event Manager 3.1

Event Detectors

Embedded Event Manager Actions

Embedded Event Manager Environment Variables

Embedded Event Manager Policy Creation

The following commands were introduced or modified by this feature:

action syslog, description (EEM), event manager applet, event manager policy, event snmp-notification, event snmp-object, show event manager policy registered, and show event manager policy available.