Cisco 4500M Command Reference Manual page 126

duplex
If the transmission speed on a 16-port RJ-45 Gigabit Ethernet port is set to 1000, duplex mode is set to
full. If the transmission speed is changed to 10 or 100, the duplex mode stays at full. You must configure
the correct duplex mode on the switch when the transmission speed changes to 10 or 100 from 1000
Mbps.
Note
Catalyst 4006 switches cannot automatically negotiate interface speed and duplex mode if either
connecting interface is configured to a value other than auto.
Caution
Changing the interface speed and duplex mode configuration might shut down and reenable the interface
during the reconfiguration.
Table2-3
The specified duplex command configured with the specified speed command produces the resulting
action shown in the table.
Table2-3
duplex Command
duplex half or duplex full
duplex half
duplex full
duplex half
duplex full
duplex full
Examples
This example shows how to configure the interface for full-duplex operation:
Switch(config-if)# duplex full
Switch(config-if)#
Related Commands
speed
interface (refer to Cisco IOS documentation)
show controllers (refer to Cisco IOS documentation)
show interfaces (refer to Cisco IOS documentation)
Catalyst4500 Series SwitchCiscoIOS Command Reference—Release 12.2(18)EW
2-94
describes the system performance for different combinations of the duplex and speed modes.
Relationship Between duplex and speed Commands
speed Command
speed auto
speed 10
speed 10
speed 100
speed 100
speed 1000
Chapter2 Cisco IOS Commands for the Catalyst 4500 Series Switches
Resulting System Action
Autonegotiates both speed and duplex modes
Forces 10 Mbps and half duplex
Forces 10 Mbps and full duplex
Forces 100 Mbps and half duplex
Forces 100 Mbps and full duplex
Forces 1000 Mbps and full duplex
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