In this case we setup a default route, which is where data packets will be sent if the router cannot determine the next hop:
california> enable california# config t california(config)# interface loopback 0 california(config-if)# ip address 1.2.3.4 255.255.255.0
R1(config)#int loopback ? <0-2147483647> Loopback interface number R1(config)#int loopback % Incomplete command. R1(config)#int loopback 0 R1(config-if)#? Interface configuration commands: access-expression Build a bridge boolean access expression arp Set arp type (arpa, probe, snap) or timeout backup Modify backup parameters bandwidth Set bandwidth informational parameter bgp-policy Apply policy propagated by bgp community string bridge-group Transparent bridging interface parameters carrier-delay Specify delay for interface transitions cdp CDP interface subcommands dampening Enable event dampening default Set a command to its defaults delay Specify interface throughput delay description Interface specific description diffserv diffserv (Provisioning) exit Exit from interface configuration mode help Description of the interactive help system hold-queue Set hold queue depth ip Interface Internet Protocol config commands keepalive Enable keepalive llc2 LLC2 Interface Subcommands load-interval Specify interval for load calculation for an interface logging Configure logging for interface max-reserved-bandwidth Maximum Reservable Bandwidth on an Interface mtu Set the interface Maximum Transmission Unit (MTU) netbios Use a defined NETBIOS access list or enable name-caching no Negate a command or set its defaults ntp Configure NTP rate-limit Rate Limit roles Specify roles (by entering roles mode) service-policy Configure QoS Service Policy shutdown Shutdown the selected interface snapshot Configure snapshot support on the interface snmp Modify SNMP interface parameters timeout Define timeout values for this interface transmit-interface Assign a transmit interface to a receive-only interface trunk-group Configure interface to be in a trunk group tx-ring-limit Configure PA level transmit ring limit R1(config-if)#ip address 1.2.3.4 255.255.255.0