2-6
Cisco 3200 Series Router Hardware Reference
OL-5816-10
Chapter 2 Cisco 3270 Rugged Router Card
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:
To set the mode on a copper Gigabit Ethernet port to duplex?
Note
The Gigabit Ethernet optical fiber interface only supports full duplex mode; a Cisco IOS command to
set the mode is not is supported.
Command
Purpose
Step 1
Router(config)#
interface GigabitEthernet
slot
/
port
Selects the Ethernet port to be configured.
Step 2
Router(config-if)#
speed
{
10
|
100
|
1000
|
auto
}
Sets the speed of the Ethernet interface.
Default
Router(config-if)#
no
speed
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.
Command
Purpose
Step 1
Router(config)#
interface GigabitEthernet
slot
/
port
Selects the Ethernet port to be configured.
Step 2
Router(config-if)#
duplex
[
auto
|
full
|
half
]
Sets the duplex mode of the Ethernet port.
Default
Router(config-if)#
no duplex
Reverts to the default configuration (
duplex
auto
).
