Loopback interfaces are very useful for giving each router its own unique identification. Also, the address assigned to the loopback interface can be used for a variety of purposes, such as the endpoints of a Tunnel line, an OSPF router ID, and the peer address for DLSW+ configurations. Their advantage is that they are always "up," regardless of the state of any other interface. If the primary router link dies and an alternate path to the router is available, Tunnels, DLSW+, and OSPF will continue to function properly. Configure a loopback with the following commands (using your own IP address):
interface loopback 0
ip address 192.9.200.33.
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