Command
Interface Loopback
Use
This command creates a logical interface on the router. These are handy from an administrative perspective because the loopback interface will also stay in a up/up state unless you shutdown the interface.
Syntax
Router(config)#interface loopback <num>
Example
In this example, we will create a new loopback interface on R3 and assign an IP address.
R3(config)#int loopback 33 *Mar 1 16:55:15.351: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback33, changed state to up R3(config-if)#ip add 113.113.113.113 255.255.255.255