Setting The Interface Duplex Mode - Cisco Catalyst 4500 Series Software Configuration Manual

This example shows how to allow the Multigigabit Ethernet interface 3/1 to autonegotiate the speed and duplex mode:
Switch(config)# interface gigabitethernet 3/1
Switch(config-if)# speed auto
This example shows how to limit speed negotiation to 2.5G on the Multigigabit Ethernet interface 3/1:
Switch(config)# interface gigabitethernet 3/1
Switch(config-if)# speed auto 2500
This example shows how to enable downshift on the Multigigabit Ethernet interface 3/1:
Switch(config)# interface gigabitethernet 3/1
Switch(config-if)# speed auto
Switch(config-if)# no disable downshift

Setting the Interface Duplex Mode

When the interface is set to 1000 Mbps, you cannot change the duplex mode from full duplex to half
Note
duplex.
To set the duplex mode of a Fast Ethernet interface, perform this task:
Command
Step 1
Switch(config)# interface fastethernet
slot/interface
Step 2
Switch(config-if)# duplex [auto | full | half]
This example shows how to set the interface duplex mode to full on Fast Ethernet interface 5/4:
Switch(config)# interface fastethernet 5/4
Switch(config-if)# duplex full
Displaying the Interface Speed and Duplex Mode Configuration
To display the interface speed and duplex mode configuration for an interface, enter this command:
Command
Switch# show interfaces [fastethernet |
gigabitethernet | tengigabitethernet]
slot/interface
Configuring Optional Interface Features
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS
9
Purpose
Specifies the interface to be configured.
Sets the duplex mode of the interface.
Purpose
Displays the interface speed and duplex mode
configuration.
Chapter 9 Configuring Interfaces