- Embedded Event Manager Overview
- Writing Embedded Event Manager Policies Using the Cisco IOS CLI
- Writing Embedded Event Manager Policies Using Tcl
- EEM Action Tcl Command Extension
- EEM CLI Library Tcl Command Extensions
- EEM CLI Library XML-PI Tcl Support
- EEM Context Library Tcl Command Extensions
- EEM Event Registration Tcl Command Extensions
- EEM Event Tcl Command Extensions
- EEM Library Debug Tcl Command Extensions
- EEM Multiple Event Support Tcl Command Extensions
- EEM SMTP Library Tcl Command Extensions
- EEM System Information Tcl Command Extensions
- EEM Utility Tcl Command Extensions
- Finding Feature Information
- 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
- 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
- Feature Information for Embedded Event Manager Overview
Embedded Event Manager Overview
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
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
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
- 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
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. The figure below 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 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
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 the table below 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 the table 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:
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 the table below 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 the table 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 the table below) 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. |
The table below 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
Additional References
The following sections provide references related to EEM.
Related Documents
| Related Topic |
Document Title |
|---|---|
| Cisco IOS commands |
|
| EEM commands: complete command syntax, defaults, command mode, command history, usage guidelines, and examples |
|
| 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: |
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. |
Feature Information for Embedded Event Manager Overview
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
| Table 4 | Feature Information for Embedded Event Manager Overview |
Cisco and the Cisco logo are trademarks or registered trademarks of Cisco and/or its affiliates in the U.S. and other countries. To view a list of Cisco trademarks, go to this URL: www.cisco.com/go/trademarks. Third-party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1110R)
Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.
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