Configuring a Serial Interface

Router(config)#int s0/0	Moves to interface Serial 0/0 mode
Router(config-if)#description Link to ISP	Optional descriptor of the link is locally significant
Router(config-if)#ip address 192.168.10.1 255.255.255.0	Assigns address and subnet mask to interface
Router(config-if)#clock rate 56000	Assigns a clock rate for the interface
Router(config-if)#no shut	Turns interface on

Tip:

The clock rate command is used only on a serial interface that has a DCE cable plugged into it. There must be a clock rate set on every serial link between routers. It does not matter which router has the DCE cable plugged into it, or which interface the cable is plugged into. Serial 0 on one router can be plugged into Serial 1 on another router.