Configuring a Loopback Interface On Cisco Router
Here, you can pick any router of your liking from the router section in the Cisco packet tracer. After picking a router, open its CLI and perform the following steps to configure a loopback interface on a router:
interface loopback 0 ip add 10.0.0.1 255.255.255.255
Configuring a Loopback Interface in Cisco
A loopback interface is used for device identification. Although you can use any interface address to determine if the device is online, we recommend using the loopback address. Network topology changes can remove interfaces or change addresses, but the loopback address never changes.