Monday, March 23, 2009

Most Useful Cisco IOS commands

I have to admit that I am not an avid cisco person. Just a make do, kind of person like most. Below is a list and explanation of the most useful cisco IOS commands that I have found in my general use. Please feel free to add stuff as you go:


1) ‘do’ command

It is a wonderful command that a nice wise guy at CISCO thought of. It was so annoying for me to constantly go back to exec mode from command mode, just to execute some exec commands viz., show.

eg: do show running-config


2) time-range

very useful for setting time-range for IP ACL lists. it works like aliases for time-ranges


time-range lunchbreak

periodic weekdays 1200 to 1300


3) show running configuration of a single interface

Another extremely useful command. Its a pain to go through the show running-config command output, specially ‘cause of the time it takes to show the config, specially on lengthy configurations. This is mostly due to the fact that it gathers all the required variables before it shows the config.

A time saver in this case is the below command:

show running config interface serial 0/0

It can also be coupled with the do command to execute the same in the config mode

do show running config interface serial 0/0


4) no ip domain-lookup

A very valuable time-saver command for me. I have fat fingers and often tend to typo on my IOS commands. I hate that the router takes a while and tries to resolve my command and takes forever to give me the prompt back. This is usually the first command I enter on a router.


5) no logging console

Are you annoyed by the constant logging of error messages on the console, that upset the continuity of your commands. Though not a problem theoretically, it is a problem when working on the console. Use the below command to get rid of that.

no logging console