Network Router User Manual
4-6
Layer 3 Switching Software Feature and Configuration Guide
78-6235-04, Cisco IOS Release 12.0(10)W5(18)
Chapter 4 Configuring Interfaces
About Layer 3 Switching Interfaces
Initially Configuring Fast Ethernet Interfaces
Use the following procedure to assign an IP address to the Fast Ethernet 10BaseT or 100BaseT interface
of your switch router so that it can be recognized as a device on the Ethernet LAN. The Fast Ethernet
interface supports 10-Mbps and 100-Mbps speeds with Cisco 10BaseT and 100BaseT routers, hubs,
switches, and switch routers.
Example
The following example demonstrates initially configuring a Fast Ethernet interface with an IP address
and autonegotiated speed and duplex:
Router(config)# interface fastethernet 1/0/0
Router(config-if)# ip address 10.1.2.4 255.0.0.0
Router(config-if)# speed auto
Router(config-if)# duplex auto
Router(config-if)# ^Z
Router# copy system:running-config nvram:startup-config
Verifying the Ethernet Interface Configuration
To verify the settings after you have configured Gigabit Ethernet or Ethernet 10/100 BaseT operation,
use the following commands:
Command Description
Step 1
Router(config)# interface fastethernet
slot/subslot/interface
Router(config-if)#
Enters Ethernet interface configuration mode to
configure the Fast Ethernet interfaces.
Step 2
Router(config-if)# ip address ip-address
subnet-mask
Specifies the IP address and IP subnet mask to be
assigned to the FastEthernet interface.
Step 3
Router(config-if)# [no] speed [10 | 100 | auto] Configures the transmission speed for 10 or
100 Mbps, or for autonegotiation (the default). If
you set the speed to auto, you enable
autonegotiation, and the switch router matches
the speed of the partner node.
Step 4
Router(config-if)# [no] duplex [full | half | auto] Configures for full or half duplex. If you set
duplex for auto, the switch router matches the
duplex setting of the partner node.
Step 5
Router(config-if)# end
Router#
Returns to privileged EXEC mode.
Step 6
Router# copy system:running-config
nvram:startup-config
Saves your configuration changes to NVRAM.
Command Purpose
show interface gigabitethernet
slot/subslot/interface
Displays the status and global parameters of the
Gigabit Ethernet interface.
show interface fastethernet
slot/subslot/interface
Displays the status and global parameters of the
Fast Ethernet interface.