Configuring the Duplex Mode

Context

Interfaces can work in the following two duplex modes:

Half-duplex mode: An interface in this mode only receives or sends data at a time within a specified transmission distance.
Full-duplex mode: An interface in this mode receives and sends data at the same time. The maximum throughput in full-duplex mode is double that in half-duplex mode, and the transmission distance is not limited.

You can configure the duplex mode of an Ethernet electrical interface working in either auto-negotiation or non-auto-negotiation mode.

In auto-negotiation mode, interfaces at both ends of a link negotiate the duplex mode. If the negotiated duplex mode is not the required value, you can manually set the duplex mode.
- If service traffic volume of enterprise users is high, interfaces at both ends of a link must work in full-duplex mode. Otherwise, packet loss occurs. You can run the auto duplex full command to set the duplex mode to full-duplex. After the auto-negotiation succeeds, the interfaces work in full-duplex mode.
- If service traffic volume of enterprise users is low, interfaces at both ends of a link can meet data transmission requirements when they work in half-duplex mode. You can run the auto duplex half command to set the duplex mode to half-duplex. After the auto-negotiation succeeds, the interfaces work in half-duplex mode.
If the remote device does not support auto-negotiation, you can manually set the duplex mode for the local interface in non-auto-negotiation mode to ensure that the local interface works in the same duplex mode as the remote interface.

For details about the duplex mode supported by Ethernet interfaces, see Licensing Requirements and Limitations for Ethernet Interfaces.

Interfaces at both ends of a link must use the same duplex mode. If two connected electrical interfaces use different auto-negotiation modes, the interfaces work in half-duplex mode after the negotiation and will fail to exchange packets properly.

Only MEth0/0/1 on the S5732-H, S6720-EI, S6720S-EI, S6720-HI, S6730-S, S6730S-S, and S6730-H supports the duplex mode configuration.

Physical service interfaces of the S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6730-H, S6730S-H, S6730-S, and S6730S-S do not support the half duplex mode.

Procedure

Configuring the duplex mode for an interface in auto-negotiation mode
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The Ethernet interface view is displayed.
3. Run negotiation auto
  The Ethernet interface is configured to work in auto-negotiation mode.
4. Run auto duplex { full | half }^*
  The duplex mode is set for the Ethernet interface.
By default, an Ethernet interface negotiates the duplex mode with the remote interface.
Configuring the duplex mode for an interface in non-auto-negotiation mode
1. Run system-view
  The system view is displayed.
2. Run interface interface-type interface-number
  The Ethernet interface view is displayed.
3. Run undo negotiation auto
  The Ethernet interface is configured to work in non-auto-negotiation mode.
4. Run duplex { full | half }
  The duplex mode is set for the Ethernet interface.
By default, the duplex mode of an Ethernet interface is full-duplex.

Verifying the Configuration

Run the display interface [ interface-type [ interface-number ] ] command in any view or the display this interface command in the interface view to check the current interface status. Check the Duplex field in the command output.