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Software Configuration Guide—Release 12.2(25)EW
OL-6696-01
Chapter 4 Configuring Interfaces
Configuring Optional Interface Features
This example shows how to allow Fast Ethernet interface 5/4 to autonegotiate the speed and duplex
mode:
Switch(config)# interface fastethernet 5/4
Switch(config-if)# speed auto
Note This is analogous to specifying speed auto 10 100.
This example shows how to limit the interface speed to 10 and 100 Mbps on the Gigabit Ethernet
interface 1/1 in auto-negotiation mode:
Switch(config)# interface gigabitethernet 1/1
Switch(config-if)# speed auto 10 100
This example shows how to limit speed negotiation to 100 Mbps on the Gigabit Ethernet interface 1/1:
Switch(config)# interface gigabitethernet 1/1
Switch(config-if)# speed auto 100
Note Turning off autonegotiation on a Gigabit Ethernet interface will result in the port being forced into
1000 Mbps and full-duplex mode.
To turn off the port speed autonegotiation for Gigabit Ethernet interface 1/1, perform this task:
To restore autonegotiation, enter the no speed nonegotiate command in the interface configuration
mode.
Note For the blocking ports on the WS-X4416 module, do not set the speed to autonegotiate.
Setting the Interface Duplex Mode
Note When the interface is set to 1000 Mbps, you cannot change the duplex mode from full duplex to half
duplex.
To set the duplex mode of a Fast Ethernet interface, perform this task:
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
Command Purpose
Step 1
Switch(config)# interface gigabitethernet1/1
Specifies the interface to be configured.
Step 2
Switch(config-if)# speed nonegotiate
Disables autonegotiation on the interface.
Command Purpose
Step 1
Switch(config)# interface fastethernet
slot/interface
Specifies the interface to be configured.
Step 2
Switch(config-if)# duplex [auto | full | half]
Sets the duplex mode of the interface.