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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
Chapter 13 Configuring Interface Characteristics Configuring Ethernet Interfaces
Caution Changing the interface speed and duplex mode configuration might shut down and re-enable the
interface during the reconfiguration.
Setting the Interface Speed and Duplex Parameters
Beginning in priv ileged EXEC mod e, follow these st eps to set the speed and duplex mode for a physical
interface:
Use the no speed and no duplex interface configuration commands to return the interface to the default
speed and duplex settings (autonegotiate). To return all interface settings to the defaults, use the default
interface interface-id interface configuration command.
Command Purpose
Step 1 configure terminal Enter global configuration mode.
Step 2 interface interface-id Specify the physical interface to be configured, and enter interface
configuration mode.
Step 3 speed {10 | 100 | 1000 | auto [10 | 100 |
1000] | nonegotiate}
This command is not available on a 10-Gigabit Ethernet interface.
Enter the appropriate speed parameter for the interface:
• Enter 10, 100, or 1000 to set a specific speed for the interface.
The 1000 keyword is available only for 10/100/1000 Mb/s ports.
• Enter auto to enable the interface to autonegotiate speed with the
connected device. If you use the 10, 100, or the 1000 keywords
with the auto keyword, the port autonegotiates only at the
specified speeds.
• The nonegotiate keyword is available only for SFP module ports.
SFP module ports operate only at 1000 Mb/s but can be
configured to not negotiate if connected to a device that does not
support autonegotiation.
For more information about speed settings, see the “Speed and Duplex
Configuration Guidelines” section on page 13-28.
Step 4 duplex {auto | full | half}This command is not available on a 10-Gigabit Ethernet interface.
Enter the duplex parameter for the interface.
Enable half-duplex mode (for interfaces operating only at 10 or
100 Mb/s). You cannot configure half-duplex mode for interfaces
operating at 1000 Mb/s.
You can configure the duplex setting when the speed is set to auto.
For more information about duplex settings, see the “Speed and
Duplex Configuration Guidelines” section on page 13-28.
Step 5 end Return to privileged EXEC mode.
Step 6 show interfaces interface-id Display the interface speed and duplex mode configuration.
Step 7 copy running-config startup-config (Optional) Save your entries in the configuration file.