eem

Cisco IOS has plenty of gems contained within, but few are as fun, and as endlessly useful as the Embedded Event Manager, or EEM. To define it simply, EEM is a technology that allows you to run a script or a set of commands upon an event. Basically, it’s an IOS scripting language that allows you to insert additional functionality to the IOS.

I think an example is in order. Lets say, you want to make sure loopback0 never gets shut down accidentally. We can create a EEM applet to watch for the syslog message that loopback0 has been shutdown, and automagicly bring it back up!

event manager applet WatchLo0
 event syslog pattern "Interface Loopback0.* down" period 1
 action 2.0 cli command "enable"
 action 2.1 cli command "config t"
 action 2.2 cli command "interface lo0"
 action 2.3 cli command "no shutdown"
 action 3.0 syslog msg "Interface Loopback0 was brought up via EEM"
!

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