Your command may be confused. General routers don't have that many Ethernet ports. When a switch has multiple ports, the interface range FastEthernet 0/0-9 command is usually used. Generally, there are two commands for a router to open a port: 1 and Ethernet port: router (config) # interface FastEthernet 0/ 1 router (config-if) # Ip address 202.3.3. 1 255.255.0 (setting the gateway) router (. No shutdown router (config-if) # exit2, serial port: router (config) # interface serial 0/3/ 0 router (config-if) # IP address 59.8.8.2 25.