Networking Exam Academy

Welcome back to another tutorial on learning how how to configure a Cisco router to help prepare you for the CCENT and CCNA Exams.

In the previous labs we learned how to use the command line interface to name your router, add a password, configure telnet and encrypt passwords. In this lab we are going to go over how to configure your ethernet interface.

Just below this paragraph you will see a terminal window for Networkcraft – The Online Network Simulator. It uses a command line interface to make configurations just like an actual Cisco Router. You will also find something simular during your simulation sections of the CCENT and CCNA Exams. Now lets get started!

Step 1: Get into interface configuration mode

Most routers have at least a couple of different interfaces on them so that they can connect to an ISP and other devices in your network like a switch. In this tutorial we are going to configure the Ethernet 0 interface. Before you can configure an interface you need to be in “interface configuration mode”. To get there, follow these commands:


Router>enable
Router#config t
Router(config)#interface e0
Router(config-if)#


Once you get into configuration mode you can type in the interface command followed by the name of the interface. For this tutorial our ethernet interface is called “e0″. Once you get into interface configuration mode you will see that the name of the prompt changed to: “Router(config-if)#”. The “if” part stands for InterFace.

Step 2: Configure The Ethernet Interface

Before the interface can be used in an actual network it needs to be configured. The interface needs to have an ip addressed with a subnet mask attached to it, and it also needs to be turned on.

Follow the step below to configure the ip address ’192.168.1.1′ with the subnet mask ’255.255.255.0′.


Router(config-if)#ip address 192.168.1.1 255.255.255.0


Step 3: Turn on the Ethernet Interface

To turn on the ethernet interface make sure you are still in interface configuration mode and type: ‘no shutdown’. If you type just ‘shutdown’ then the interface will be turned off. And so to turn it on you will type ‘no shutdown as shown below:


Router(config-if)#no shutdown


Step 4: Verify Configuration

It’s always a good habit to verify your configuration. To do this let’s look at our running configuration by typing in the following commands. Typing exit twice takes you out of interface configuration mode and then configuration mode. Typing in ‘sh run’ prints out the running configuration of your router.


Router(config-if)#exit
Router(config)#exit
Router#sh run


Your console screen should now be filled up with your running configuration. If you scroll down through it you should see a line that starts with “Interface Ethernet 0″ followed by the settings we just configured. Below is an example screen shot of what your running configuration should look like:

That concludes this lab. I’m not completely sure yet, but the next lab that I want to do will show you how to configure interfaces on two different routers and ping between them.

Thanks for going through this lab and if you have any questions, comments, or requests please comment below. I would love to hear from you!

Thanks,
-Blake Erickson

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Photo Credit: Denby Jorgensen