Cisco Catalyst 3750 Command Reference Manual page 112

duplex
If both ends of the line support autonegotiation, we highly recommend using the default autonegotiation
settings. If one interface supports autonegotiation and the other end does not, configure duplex and speed
on both interfaces; do use the auto setting on the supported side.
If the speed is set to auto, the switch negotiates with the device at the other end of the link for the speed
setting and then forces the speed setting to the negotiated value. The duplex setting remains as
configured on each end of the link, which could result in a duplex setting mismatch.
Changing the interface speed and duplex mode configuration might shut down and reenable the interface
Caution
during the reconfiguration.
For guidelines on setting the switch speed and duplex parameters, refer to the software configuration
Note
guide for this release.
Examples
This example shows how to configure an interface for full duplex operation:
Switch(config)# interface gigabitethernet1/0/1
Switch(config-if)# duplex full
You can verify your setting by entering the show interfaces privileged EXEC command.
Related Commands Command
show interfaces
speed
Catalyst 3750 Switch Command Reference
2-86
Description
Displays the interface settings on the switch.
Sets the speed on a 10/100 or 10/100/1000 Mbps interface.
Chapter 2 Catalyst 3750 Switch Cisco IOS Commands
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