Cisco iOS Basics: Assigning IP addresses

In order for interface on the Cisco router to work, it needs IP address.

Procedure for assigning IP address is pretty simple.

Before proceeding to IP config it would be wise to check state of the available interfaces.

It can be done from Privileged EXEC mode with

Zeljko#show ip interface brief

Same command can be also accessed from Global config mode with a little change, adding do before show.

Zeljko(config)#do show ip interface brief

Here is the result


Ports don’t have IP addresses and are in the down state.

Lets configure FastEthernet0/0

Zeljko(config)#interface FastEthernet 0/0
Zeljko(config-if)#ip address
Zeljko(config-if)#no shut

%LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up


With command Zeljko(config)#interface FastEthernet 0/0 we entered configuration mode of port FastEthernet 0/0 (FE0/0)

Command ip address adds IP address to port FE0/0

Last command Zeljko(config-if)#no shut or no shutdown brings FE0/0 from down (offline)  state to up (online)
Lets check port configuration once more with

Zeljko(config)#do show ip interface brief


Port is up with address we assigned.

If you want to remove IP address from interface, procedure is pretty simple

Zeljko(config)#interface fastethernet0/0
Zeljko(config-if)#no ip address

And if you want to bring down (offline)  interface on Cisco router


That would be basic interface configuration  on Cisco