Ethernet Port Speed And Duplex Mode - Cisco 3200 Series Hardware Reference Manual

Ethernet Port Speed and Duplex Mode

The router cannot automatically negotiate port speed and duplex mode unless the connecting port is
configured speed auto, duplex auto, or no speed. If the port speed is set to a value other than auto, such
as 10, 100, or 1000-Mbps, configure the remote link partner port to match the local settings; do not
configure the link partner port to auto.
If a copper Gigabit Ethernet port speed is configured as 1000-Mbps, it must be configured as duplex
auto mode; otherwise the link will not come up. We recommend that you use the speed auto command
and duplex auto command to configure a Gigabit Ethernet port.
The fiber-optic Gigabit Ethernet port does not allow users to configure the mode as speed or duplex. The
port speed and mode are determined by the SFP module.
Note Changing the Ethernet port speed and duplex mode configuration might shut down and reenable the
interface during the reconfiguration.
The procedure to set the port speed for a copper Gigabit Ethernet port is as follows:
Command
Step 1 Router(config)# interface GigabitEthernet slot/port
Step 2 Router(config-if)# speed {10 | 100 | 1000 | auto}
Default Router(config-if)# no speed
To set the mode on a copper Gigabit Ethernet port to duplex?
Command
Step 1 Router(config)# interface GigabitEthernet slot/port
Step 2 Router(config-if)# duplex [auto | full | half]
Default Router(config-if)# no duplex
The Gigabit Ethernet optical fiber interface only supports full duplex mode; a Cisco IOS command to
Note
set the mode is not is supported.
Cisco 3200 Series Router Hardware Reference
2-6
Chapter 2 Cisco 3270 Rugged Router Card
Purpose
Selects the Ethernet port to be configured.
Sets the speed of the Ethernet interface.
Reverts to the default configuration (speed
auto). If you set the port speed to auto on a
10/100/1000-Mbps Ethernet port, speed is
autonegotiated.
Purpose
Selects the Ethernet port to be configured.
Sets the duplex mode of the Ethernet port.
Reverts to the default configuration (duplex
auto).
OL-5816-10