This short tutorial will show you how to configure an interface in Cisco IOS, assign IP address to it, and then enabling it.

Enter exec mode.

Router>enable
Router#


Check the available interfaces of the router.

Router#show ip interface brief
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet0/0            unassigned      YES unset  administratively down down
FastEthernet0/1            unassigned      YES unset  administratively down down

Note the status is “administratively down” and protocol is “down”. That means the interface is not up yet.

Lets configure the interface FastEthernet0/0
Configure Terminal.

Router#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#

Configure Interface FastEthernet0/0, assigning Class C ip address and then enabling it.

Router(config)#interface fastEthernet 0/0
Router(config-if)#ip address 192.168.1.2 255.255.255.0
Router(config-if)#no shutdown

Lets check the status of the Fast Ethernet 0/0 interface.
Press Ctrl+Z to exit the config mode

Router(config)#^Z
Router#
*Mar  1 00:11:41.079: %SYS-5-CONFIG_I: Configured from console by console
Router#

Check the status

Router#show ip interface brief
Interface                  IP-Address      OK? Method Status                Protocol
FastEthernet0/0            192.168.1.2     YES manual up                    up
FastEthernet0/1            unassigned      YES unset  administratively down down

Note that the Status and Protocol are both “up”, that means the interface has been configured working properly.

That concludes Configuring Interface tutorial.