Ethernet, Fast Ethernet, and Gigabit Ethernet Interfaces

Give an Ethernet, Fast Ethernet, or Gigabit Ethernet interface an IP address, and it's ready to go. It's a good idea to give the interface a description, but that's not required. Also, as with all interfaces, don't forget the no shutdown command. For Fast Ethernet interfaces , you can also specify the interface speed and whether it's operating at full or half duplex:

interface Ethernet0
 description Internal Office Network
 ip address 10.10.1.1 255.255.255.248
 no shutdown
!
interface FastEthernet1
 description Fast Network for fileservers
 ip address 10.10.1.17 255.255.255.248
 ! Set the speed to 100 (which is the default)
 speed 100
 ! Set the duplex to full
 duplex full
 no shutdown
!
interface gigabitethernet 0/0
 description our new gigabit ethernet network
 ip address 10.10.5.1 255.255.255.0
 duplex full
 no shutdown