interface [interface] [slot/port]

Sets the interface to be configured.

Syntax: interface [interface name] [slot/port]

Example: Set the configuration mode for the gigabit ethernet interface in slot 0 port 8

Router(config)# interface gigabitEthernet 0/8

Example: Set the configuration mode for the ethernet interface in slot 0 port 2

Router(config)# interface fastEthernet 0/2

Note: after entering the interface command, notice how the command prompt changes to show that the mode is configure interface.