Introduction:
The EEM(Embedded Event manager is a software component of cisco IOS, XR, and NX-OS makes life easier for administrators by tracking and classifying events that take place on a router and providing notification options for those events. EEM allows you to automate tasks, perform minor enhancements and create workarounds.
There are two independent pieces: Applets and Scripting
-> Applets are a collection of CLI commands
-> Scripts are actions coded up in TCL(interpreter language)
EEM uses event detectors and actions to provide notifications of those events:
EEM detectors can be:
1) SNMP:-Monitoring SNMP objects.
2) Syslog:-Responds to various syslog messages, allowing for matching on regular expressions.
3) Counter: Monitoring and responding to interface counter when cross threshold settings.
4) CLI events: Screening CLI input for a regular expression match.
5) None: This event detector is use to test EEM script/applet using "event manager run" command.
6) Timers :(Countdown, watchdog and CRON)
7) IP SLA and Netflows events.
Common regular expressions:
^ = Start of string
$ = End of string
. = Any single character
* = Zero or more instances
+ = One or more instance
? = Zero or one instance
EEM Actions can be:
1)Sending a email messages
2)Executing a cisco command.
3)Generating SNMP traps
4)Reloading the router
5)Generating priotized syslog messages
6)Switching to a secondary processor in a redundant platform
7)requesting system information when an event occurs(like sh tech,sh proccess cpu history).
Sample EEM Scripts:
A) Syslog Event detector:
This example shows the syslog event detector. When the ISP1 interface has been shutdown, the below applet run to turn on the interface and send the alert to the below mention mail id with logged in users information.
Configuration:
event manager applet interface_Shutdown
event syslog pattern "Interface FastEthernet1/0, changed state to administratively down"
action 1.0 cli command "enable"
action 1.5 cli command "config t"
action 2.0 cli command "interface fa1/0"
action 2.5 cli command "no shutdown"
action 3.0 cli command "end"
action 3.5 cli command "who"
action 4.0 mail server "192.168.1.1" to ".engineer@cisco.com." from ".EEM@cisco.com." subject ".ISP1_Interface_fa1/0_SHUT." body "Current users $_cli_result"
Enabling debug detector to get closer view and shutdown the interface fa1/0.
R1#debug event manager action cli
Debug EEM action cli debugging is on
R1#conf tEnter configuration commands, one per line. End with CNTL/Z.R1(config-if)#int fa1/0
R1(config-if)#sh
*Nov 17 23:06:24.215: %LINK-5-CHANGED: Interface FastEthernet1/0, changed state to administratively down
*Nov 17 23:06:24.283: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : CTL : cli_open called.
*Nov 17 23:06:24.295: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : OUT : R1>
*Nov 17 23:06:24.299: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : IN : R1>enable
*Nov 17 23:06:24.319: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : OUT : R1#
*Nov 17 23:06:24.319: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : IN : R1#config t
*Nov 17 23:06:24.343: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : OUT : Enter configuration commands, one per line. End with CNTL/Z.
R1(config-if)#
*Nov 17 23:06:24.347: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : OUT : R1(config)#
*Nov 17 23:06:24.347: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : IN : R1(config)#interface fa1/0
*Nov 17 23:06:24.467: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : OUT : R1(config-if)#
*Nov 17 23:06:24.467: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : IN : R1(config-if)#no shutdown
*Nov 17 23:06:24.587: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : OUT : R1(config-if)#
*Nov 17 23:06:24.587: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : IN : R1(config-if)#end
*Nov 17 23:06:24.643: %SYS-5-CONFIG_I: Configured from console by on vty0 (EEM:interface_Shutdown)
*Nov 17 23:06:24.655: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : OUT : R1#
*Nov 17 23:06:24.655: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : IN : R1#who
*Nov 17 23:06:24.727: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : OUT : Line User
R1(config-if)#Host(s) Idle Location
*Nov 17 23:06:24.731: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : OUT : 0 con 0 idle 00:00:02
*Nov 17 23:06:24.731: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : OUT : * 2 vty 0 idle 00:00:00 EEM:interface_Shutdown
*Nov 17 23:06:24.735: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : OUT :
*Nov 17 23:06:24.735: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : OUT : Interface User Mode Idle Peer Address
*Nov 17 23:06:24.735: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : OUT :
*Nov 17 23:06:24.739: %HA_EM-6-LOG: interface_Shutdown : DEBUG(cli_lib) : : OUT : R1#
R1(config-if)#
*Nov 17 23:06:26.487: %LINK-3-UPDOWN: Interface FastEthernet1/0, changed state to up
B) CLI Event detector:
In this example applet has created to stop "debugging" command on the CLI. If anyone enter the debug command it will have no effect, also clock and user’s information will be stored in flash.
Configuration:
event manager applet Stop_Debug
event cli pattern "debug" sync no skip yes
action 1.0 cli command "enable"
action 2.0 cli command "sh users | append flash:Debug"
action 3.0 cli command "sh clock | append flash:Debug_clock"
Verification:
Checking the registered applet with following command:
R1#sh event manager policy registered
No. Class Type Event Type Trap Time Registered Name
1 applet user cli Off Fri Mar 1 00:08:05 2002 Stop_Debug
pattern {debug} sync no skip yes
maxrun 20.000
action 1.0 cli command "enable"
action 2.0 cli command "sh users | append flash:Debug"
action 3.0 cli command "sh clock | append flash:Debug_clock"
R1#debug all
R1#debug event manager action cli
R1#sh debugging......(Not showing any debug running on device)
R1#sh flash:
System CompactFlash directory:
File Length Name/status
1 1614 Debug.....(User info is append to flash)
2 204 Debug_clock......(Clock time when debug entered is also append to flash)R1#more flash:Debug
Line User Host(s) Idle Location
0 con 0 idle 00:00:00
* 66 vty 0 idle 00:00:00 XYZ
Interface User Mode Idle Peer Address
R2#more flash:Debug_Clock
12:43:15.263 UTC Sun Nov 18 2012
R2#
C) Interface Events:
In this example applet is configure to measure rxload on the interface.
Two applets are configure:
1) When Rx load is above 50% then router will apply access-list on the interface fa0/1 to allow only important traffic and block the unwanted traffic.
2) When Rx load goes below 25, the router will remove applied access-list from the interface fa0/1 to allow all traffic.
Configuration:
event manager applet Interface_Load_UP
event tag 1 interface name FastEthernet1/0 parameter rxload entry-op gt entry-val 127 entry-type value poll-interval 30
action 1.0 cli command "enable"
action 1.1 cli command "conf t"
action 1.2 cli command "int fa1/0"
action 1.3 cli command "ip access-group IMP_TRAFFIC in "
action 1.4 cli command "end"
event manager applet Interface_Load_Down
event tag 1 interface name FastEthernet1/0 parameter rxload entry-op lt entry-val 25 entry-type value poll-interval 30
action 1.0 cli command "enable"
action 1.1 cli command "conf t"
action 1.2 cli command "int fa1/0"
action 1.3 cli command "no ip access-group IMP_TRAFFIC in "
action 1.4 cli command "end"
Verification:
R1#sh int fa1/0 | in load
reliability 255/255, txload 1/255, rxload 1/255..(Rxload is 1)
R1#debug event manager action cli
Debug EEM action cli debugging is on
R1#sh int fa1/0 | in load
reliability 255/255, txload 139/255, rxload 139/255....(Rxload is increase more 50% i.e.139)
R1#(As soon Rxload increase by 50%, causing to triggered 1 st event)
*Nov 18 02:19:55.403: %HA_EM-6-LOG: Interface_Load : DEBUG(cli_lib) : : CTL : cli_open called.
*Nov 18 02:19:55.423: %HA_EM-6-LOG: Interface_Load : DEBUG(cli_lib) : : OUT : R1>
*Nov 18 02:19:55.427: %HA_EM-6-LOG: Interface_Load : DEBUG(cli_lib) : : IN : R1>enable
: R1#conf t
: R1(config)#int fa1/0
: R1(config-if)#ip access-group IMP_TRAFFIC in....(Access-list apply to interface)
*Nov
R1#18 02:19:55.827: %HA_EM-6-LOG: Interface_Load : DEBUG(cli_lib) : : OUT : R1(config-if)#
*Nov 18 02:19:55.831: %HA_EM-6-LOG: Interface_Load : DEBUG(cli_lib) : : IN : R1(config-if)#end
*Nov 18 02:19:55.839: %SYS-5-CONFIG_I: Configured from console by on vty0 (EEM:Interface_Load)
*Nov 18 02:19:55.851: %HA_EM-6-LOG: Interface_Load : DEBUG(cli_lib) : : OUT : R1#
*Nov 18 02:19:55.855: %HA_EM-6-LOG: Interface_Load : DEBUG(cli_lib) : : CTL : cli_close called.
R1#sh ip access-lists
Extended IP access list IMP_TRAFFIC
10 permit tcp any any eq www
20 permit tcp any any eq telnet
30 deny icmp any any (10 matches)............(Router Start dropping ICMP packets)
R1#sh run int fa1/0
Building configuration...
Current configuration : 159 bytes
!
interface FastEthernet1/0
bandwidth 64
ip address 10.1.1.1 255.255.255.0
ip access-group IMP_TRAFFIC in
load-interval 30
duplex full
speed 100
!
end
R1#sh int fa1/0 | in load
reliability 255/255, txload 19/255, rxload 19/255(As soon as Rxload goes below 25, R1 trigger 2nd event)
R1#
*Nov 18 02:21:31.367: %HA_EM-6-LOG: Interface_Load_Down : DEBUG(cli_lib) : : CTL : cli_open called.
*Nov 18 02:21:31.375: %HA_EM-6-LOG: Interface_Load_Down : DEBUG(cli_lib) : : OUT : R1>
*Nov 18 02:21:31.379: %HA_EM-6-LOG: Interface_Load_Down : DEBUG(cli_lib) : : IN : R1>enable
*Nov 18 02:21:31.395: %HA_EM-6-LOG: Interface_Load_Down : DEBUG(cli_lib) : : OUT : R1#
*Nov 18 02:21:31.399: %HA_EM-6-LOG: Interface_Load_Down : DEBUG(cli_lib) : : IN : R1#conf t
*Nov 18 02:21:31.423: %HA_EM-6-LOG: Interface_Load_Down : DEBUG(cli_lib) : : OUT : Enter configuration commands, one per line. End with CNTL/Z.
R1#
*Nov 18 02:21:31.423: %HA_EM-6-LOG: Interface_Load_Down : DEBUG(cli_lib) : : OUT : R1(config)#
*Nov 18 02:21:31.427: %HA_EM-6-LOG: Interface_Load_Down : DEBUG(cli_lib) : : IN : R1(config)#int fa1/0
*Nov 18 02:21:31.455: %HA_EM-6-LOG: Interface_Load_Down : DEBUG(cli_lib) : : OUT : R1(config-if)#
*Nov 18 02:21:31.459: %HA_EM-6-LOG: Interface_Load_Down : DEBUG(cli_lib) : : IN : R1(config-if)#no ip access-group IMP_TRAFFIC in....(Removing Access-list)
*Nov 18 02:21:31.579: %HA_EM-6-LOG: Interface_Load_Down : DEBUG(cli_lib) : : OUT : R1(config-if)#
*Nov 18 02:21:31.579: %HA_EM-6-LOG: Interface_Load_Down : DEBUG(cli_lib) : : IN : R1(config-if)#end
*Nov 18 02:21:31.587: %SYS-5-CONFIG_I: Configured from console by on vty0 (EEM:Interface_Load_Down)
*Nov 18 02:21:31.599: %HA_EM-6-LOG: Interface_Load_Down : DEBUG(cli_lib) : : OUT : R1#
*Nov 18 02:21:31.603: %HA_EM-6-LOG: Interface_Load_Down : DEBUG(cli_lib) : : CTL : cli_close called.
D) SNMP event Detector:
In this example EEM applet reads the SNMP variable and it will be triggered when the CPU goes above 60 %.you can customized applet according to the need. However, caution should be exercised to consider the file system free space before deploying the applet.
For SNMP OID you can use SNMP Object Navigator
Configuration:
event manager applet HIGH-CPU
!
event snmp oid 1.3.6.1.4.1.9.9.109.1.1.1.1.3 get-type next entry-op gt entry-val 60 poll-interval 5
!
action 0.1 cli command "enable"
action 0.2 syslog msg "Capturing high cpu information to flash:"
action 0.3 cli command "term length 0"
action 1.1 cli command "show process cpu sorted | append flash:EEM_CPU"
action 1.4 cli command "show ip traffic | append flash:EEM_TRAFFIC"
action 1.4 cli command "show logging | append flash:EEM_LOGS"
action 4.2 syslog msg "Removing EEM APPLET from running_config"
action 9.2 cli command "configure terminal"
action 9.3 cli command "no event manager applet HIGH-CPU"
action 9.4 cli command "end"
action 9.5 cli command "term default length"
Verification:
R2#
*Nov 18 12:30:53.139: %HA_EM-6-LOG: HIGH-CPU: Capturing high cpu information to flash:
*Nov 18 12:30:53.371: %HA_EM-6-LOG: HIGH-CPU: Removing EEM APPLET from running_config
R2#sh flash:
System CompactFlash directory:
File Length Name/status
1 22477 EEM_CPU
2 2665 EEM_LOGS
E) TCL (Tool Control Language) is a scripting language used extensively by Cisco to facilitate the testing and automating of various functions in the IOS.
In this example, small TCL script configured to check reachability of Branch devices from the Core router.
R1#tclsh
R1(tcl)#
R1(tcl)#foreach VAR {
+>(tcl)#192.168.1.1
+>(tcl)#192.168.2.1
+>(tcl)#192.168.3.1
+>(tcl)#192.168.4.1
+>(tcl)#} { puts [exec "ping $VAR"] }
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/58/120 ms
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/40/104 ms
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.3.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/72/128 ms
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.4.1, timeout is 2 seconds:
U.U.U
Success rate is 0 percent (0/5)
R1(tcl)#
Related Information
Writing Embedded Event Manager Policies Using the Cisco IOS CLI
Cisco EEM Best Practices
Embedded Event Manager Overview
emm through event manager scheduler script
Writing Embedded Event Manager Policies Using Tcl
EEM Script For Periodically Clearing Interface Counters Using Regular Expression
Base Initial configuration:
