Because a loopback interface is always available as long as the device is available,
it allows routing protocol sessions to stay up even if the outbound interface is down.
Assigning a loopback interface to a VRF is similar to assigning any interface. A loopback
interface that is not assigned to a nondefault VRF belongs to the default VRF.
Enter global configuration mode.
device# configure terminal
In global configuration mode, enter interface subtype configuration mode and assign
a loopback interface.
device(config)# interface loopback 1
Use the
vrf forwarding command to assign the interface to the VRF "customer-1" in this example.
device(config-lbif-1)# vrf forwarding customer-1
Assign an IPv4 address and mask to the loopback interface.