Cisco Catalyst 3550 Command Reference Manual page 476

speed
If both ends of the line support autonegotiation, we highly recommend 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 both the speed and duplex are set to specific values, autonegotiation is disabled.
Changing the interface speed and duplex mode configuration might shut down and re-enable the
Caution
interface 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 set the specified interface to 100 Mbps:
Switch(config)# interface gigabitethernet0/1
Switch(config-if)# speed 100
You can verify your settings by entering the show interfaces privileged EXEC command.
Related Commands Command
duplex
show interfaces
Catalyst 3550 Multilayer Switch Command Reference
2-450
Description
Specifies the duplex mode of operation for Fast Ethernet and Gigabit
Ethernet ports.
Displays the statistical information specific to all interfaces or to a specific
interface
Chapter 2 Cisco IOS Commands
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