The Cisco EEM allows the behavior of a Cisco device to adapt to specific user requirements by allowing scripting, thresholding, proactive actions, data collection and event management inside the Cisco device itself. Using EEM, problems can be identified and resolved automatically in advance by setting event triggers (called Event Detectors) to watch for specific types of situations or thresholds, or run a set of actions periodically.

With EEM, users can capture complex network events and run sophisticated programs on Cisco devices. The version of EEM on most Cisco devices is version 2.1, and the latest version is 3.0 which was introduced in IOS 12.4(22)T. EEM consists of three areas; Event Detectors, Policies and Programming languages.

When a situation is detected by EEM, it uses policies to invoke actions based on the type of event and the configured policy.

There is a cool handy way to know TTY sessions established in any Cisco Router or a Cisco Switch. By using this feature you can know the number of active telnet sessions from the prompt itself.

Normally whenever you log to any Cisco Router or Switch you will find this menu

ITKE-AS01#

By using the “prompt” command you can see the difference

You might be wondering how come this is possible, ok now let me show you how to enable this feature in a Cisco Router or a Cisco Switch,

Log in to your Cisco Device and use the following command “prompt %h:%n%p”

ITKE-AS01#config t

ITKE-AS01 (config)# prompt %h:%n%p
ITKE-AS01 (config)# exit

In the example I have used three escape sequences to set the prompt name to the hostname (%h), followed by the command number (%n) and then followed by the appropriate prompt character for the current command mode (%p).

You can see the difference in the hostname after applying the “prompt %h:%n%p” command.

ITKE-AS01:1#sho users

    Line       User       Host(s)              Idle       Location

*  1 vty 0     yasir      idle                 00:00:00 10.0.0.5

  Interface      User        Mode                     Idle     Peer Address

ITKE-AS01:1#

As the number of TTY session increases you can see the incremental change in the hostname with the sequence number as displayed below.

Example with two TTY sessions

ITKE-AS01:2#sho users

    Line       User       Host(s)              Idle       Location

   1 vty 0     yasir      idle                 00:00:23 10.0.0.5

*  2 vty 1     itkeuser      idle                 00:00:00 10.0.0.5

  Interface      User        Mode                     Idle     Peer Address

ITKE-AS01:2#

Example with three TTY sessions

ITKE-AS01:3#sho users

    Line       User       Host(s)              Idle       Location

   1 vty 0     yasir      idle                 00:01:14 10.0.0.5

   2 vty 1     itkeuser      idle           00:00:50 10.0.0.6

*  3 vty 2     itkeadmin   idle         00:00:00 10.0.0.7

  Interface      User        Mode                     Idle     Peer Address

ITKE-AS01:3#

Example with four TTY sessions

ITKE-AS01:4#sho users

    Line       User       Host(s)              Idle       Location

   1 vty 0     yasir      idle                 00:01:43 10.0.0.5

   2 vty 1     itkeuser      idle            00:01:20 10.0.0.6

   3 vty 2     itkeadmin   idle            00:00:29 10.0.0.7

*  4 vty 3     yasir      idle                 00:00:00 10.0.0.5

  Interface      User        Mode                     Idle     Peer Address

ITKE-AS01:4#

I you want to disable the TTY display enter the “no prompt” command as shown below.
ITKE-AS01:4#config t
ITKE-AS01:4 (config)# no prompt

Following are the prompt Variables available for the “prompt” command.