Interface

interface Loopback <N>

Create a virtual interface that's always up — perfect for stable router-IDs.

Works on: RouterMode: config

Example

R1(config)# int Loopback 0
R1(config-if)# ip address 1.1.1.1 255.255.255.255

Run this command live

Don't just read it — type interface Loopback <N> in a real network simulator in your browser and watch it take effect. No install, no account needed to start.

Open the lab

Frequently asked

What does the "interface Loopback <N>" command do?

Create a virtual interface that's always up — perfect for stable router-IDs.

Example of "interface Loopback <N>"

R1(config)# int Loopback 0 R1(config-if)# ip address 1.1.1.1 255.255.255.255

More Interface commands

interface <id>ip address <ip> <mask>ip address dhcp no shutdown shutdown description <text>interface <iface>.<sub>encapsulation dot1Q <vlan>

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