Article

5 Cisco IOS Commands Every Network Admin Should Know

July 20, 2020

There are 5 fundamental Cisco commands that every Cisco network administrator should know. These are useful commands that can be implemented on a Cisco router to quickly gather important information and save changes. Consider adding these commands to your Cisco commands cheat sheet so you can reference them when you’re working on your Cisco router.

If you are new to Cisco networking, these are great commands to memorize. If you’re an experienced administrator, you may enjoy a refresher on a few of these commands.

We’ll start the list at #5 and move to #1.

IOS command #5: Show interfaces

It’s important to know what type of interfaces are on your router, important statistics about those interfaces and whether they are up or down. The show interfaces command is a very verbose command that provides a lot of output. You may have to pick through that output to find what you are looking for; just about everything to do with interfaces is shown in the output from this command, for example interface type, speed, IP address, and errors on the interface. This command can be used in both User EXEC and Privileged EXEC mode.

This command can be abbreviated as sh int.

IOS command #4: Copy running-config startup-config

Once you make changes to the router’s configuration, it’s important to remember to save those changes. This command copies the active running config in RAM that you have modified to the startup config in flash memory. By copying the configuration into flash, it  will be saved when the router is powered off and restarted. This command can only be used in Privileged EXEC mode.

A shortcut for this command is wr (which is short for write memory).

IOS command #3: Show IP route

Routers learn about networks, either statically or dynamically, and save the best path to those networks in their routing table. Once you know that your interfaces are up and you have saved your configuration, you want to verify that your router has convergence, which means that your router has accurate information about network reachability. The show IP route command displays every known connected and destination network, the method used to learn about these networks, the next-hop IP address and the local interface used to get to each known destination network. This command can be used in both User-EXEC and Privileged EXEC mode.

This command can be abbreviated sh ip ro.

IOS command #2: Show IP interface brief

We mentioned that the show interfaces command gives you a lot of useful information about all your router’s interfaces. Sometimes you want precise, specific information to answer the questions: Is the interface up? What are the IP addresses assigned to the interfaces? The show IP interface brief command gives you the answers to these questions and is the best summary of the status, protocol and IP addresses of your interfaces. This command can be used in both User EXEC and Privileged EXEC mode.

This command can be abbreviated sh ip int brie.

And the #1 most important command that every Cisco network administrator should know is...

IOS command #1: Show running-config

Probably the most useful of all the Cisco show commands is show running-config. With this command, you get to see the router's entire active configuration. Every command you have typed. Every default command applied. All this great information is available with a single IOS command. It’s that simple. You get to see the IP addresses, interfaces, passwords (that are in clear text), routing protocols and other settings. This command can only be used in Privileged EXEC mode.

This command can be abbreviated sh run or wr t.

Summary

Using the Cisco IOS is all about knowing what command to type to access the information you need and make the changes you need to make. The 5 Cisco router commands shown in this article are just a few of the thousands of possible Cisco IOS commands, however, this Cisco commands list contains some of the most useful commands that every Cisco network administrator should know.

 

Author Sean Douglas has more than 17 years of experience working extensively with Cisco technology. For the last decade, he has worked as a Cisco Systems Engineer that consults with a variety of clients to design, implement, build from the ground up, and maintain their Cisco Collaboration Solutions. Sean is CCNP in Routing and Switching, Wireless, and Collaboration.