duplex (Management interface view)

Function

The duplex command configures a duplex mode for an Ethernet interface.

The undo duplex command restores the default duplex mode of an Ethernet interface.

The default duplex mode of an Ethernet interface is auto-negotiation mode.

Format

duplex half

duplex full

duplex auto

undo duplex

Parameters

Parameter	Description	Value
full	Indicates the full duplex mode. When connecting to LAN switches, electrical Ethernet interfaces on devices can work in either full duplex or half duplex mode.	-
auto	Indicates the auto-negotiation mode. In auto-negotiation mode, the local device automatically adjusts the interface rate and duplex mode based on the interface rate and duplex mode of the peer so that both ends can work in the same duplex mode at the highest possible speed. It is recommended that Ethernet interfaces work in auto-negotiation mode provided that the interfaces support this mode. Auto-negotiation is disabled only when two ends of a link work at mismatched rates or duplex modes. In this case, you need to manually set the interface rate and duplex mode.	-
half	Indicates the half duplex mode. When connecting to hubs, electrical Ethernet interfaces on devices must work in half duplex mode because hubs work only in half duplex mode.	-

Parameter

Description

Value

full

Indicates the full duplex mode.

When connecting to LAN switches, electrical Ethernet interfaces on devices can work in either full duplex or half duplex mode.

auto

Indicates the auto-negotiation mode.

In auto-negotiation mode, the local device automatically adjusts the interface rate and duplex mode based on the interface rate and duplex mode of the peer so that both ends can work in the same duplex mode at the highest possible speed.

It is recommended that Ethernet interfaces work in auto-negotiation mode provided that the interfaces support this mode. Auto-negotiation is disabled only when two ends of a link work at mismatched rates or duplex modes. In this case, you need to manually set the interface rate and duplex mode.

half

Indicates the half duplex mode.

When connecting to hubs, electrical Ethernet interfaces on devices must work in half duplex mode because hubs work only in half duplex mode.

Views

Management interface view

Default Level

2: Configuration level

Task Name and Operations

Task Name	Operations
device-mgr	write

Usage Guidelines

Usage Scenario

On a large-scale Ethernet network, manually setting the interface rate and duplex mode, verifying the configurations of devices, and checking statistics about Ethernet interfaces require a great deal of time and human input. Therefore, it is recommended that manually setting the interface rate and duplex mode be adopted only when auto-negotiation of an Ethernet link fails or a problem occurs with auto-negotiation. When there is an auto-negotiation problem, you are recommended to upgrade software or hardware of the device to support the auto-negotiation standard defined in IEEE802.3u/z.

If both ends support auto-negotiation, the duplex mode with a lower priority is adopted. Interconnected devices working in auto-negotiation mode is the prerequisite to the auto-negotiation mechanism. If one end works in auto-negotiation mode while the other end works in fixed mode, the auto-negotiation mechanism does not take effect.

The auto-negotiation priorities of Ethernet interface rates and duplex modes are listed as follows in descending order:

1000M full duplex
1000M half duplex
100M full duplex
100M half duplex
10M full duplex
10M half duplex
Manually setting the interface rate and duplex mode usually complicates network planning and maintenance, and incorrect setting may affect even interrupt normal communication on the network. For example, during network planning, you can set the duplex mode of the local interface same as the known peer duplex mode by running the duplex command. However, once the duplex mode of the peer interface changes, the communication quality will be affected if the duplex mode of the local interface does not change.

Configuration Impact

Changing the rate or the duplex mode of an interface interrupts network communication for a short period.

Duplex modes of the Ethernet interfaces at the two ends of a link must be the same

Example

# Configure GigabitEthernetGigabitEthernet0/0/0 to work in full duplex mode.

<HUAWEI> system-view
[~HUAWEI] interface GigabitEthernetGigabitEthernet0/0/0
[~HUAWEI-GigabitEthernetGigabitEthernet0/0/0] duplex full