#configure terminal | Enter configure mode. |
(config)#interface lo | Enter interface mode for loopback. |
(config-if)#ip address 1.2.3.4/32 | Configure the loopback IP address. |
(config-if)#interface eth1 | Enter interface mode. |
(config-if)#ip address 100.1.1.1/24 | Configure the IP address for interface eth1. |
#exit | Exit interface mode. |
(config)#router ospf 100 | Configure OSPF. |
(config-router)#network 1.2.3.4/32 area 0 | Add loopback IP address to OSPF network. |
(config)-router#network 100.1.1.0/24 area 0 | Add eth1 IP address to OSPF network. |