To do…

 

Use the command…

 

Remarks

 

 

 

Configure the system to run

 

 

 

Optional

 

 

 

 

 

 

By default, the system runs

 

 

 

loopback detection on all

 

loopback-detection per-vlan

 

 

 

 

 

 

loopback detection only on the

 

 

 

VLANs for the trunk and hybrid

 

enable

 

 

 

 

 

 

default VLAN for the trunk and

 

 

 

ports

 

 

 

 

 

 

 

 

 

hybrid ports.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

z

z

z

To enable loopback detection on a specific port, you must use the loopback-detection enable command in both system view and the specific port view.

After you use the undo loopback-detection enable command in system view, loopback detection will be disabled on all ports.

The commands of loopback detection feature cannot be configured with the commands of port link aggregation at the same time.

Configuring the Ethernet Port to Run Loopback Test

You can configure the Ethernet port to run loopback test to check if it operates normally. The port running loopback test cannot forward data packets normally. The loopback test terminates automatically after a specific period.

Follow these steps to configure an Ethernet port to run loopback test:

 

To do…

Use the command…

Remarks

 

 

Enter system view

system-view

 

 

 

 

 

 

 

Enter Ethernet port view

interface interface-type

 

 

interface-number

 

 

 

 

 

 

 

 

 

 

 

Configure the Ethernet port to run

loopback { external internal }

Required

 

 

loopback test

 

 

 

 

 

 

 

 

 

 

z

z

external: Performs external loop test. In the external loop test, self-loop headers (which are made from four cores of the 8-core cables) must be used on the ports of the device. The external loop test can locate the hardware failures on the port.

internal: Performs internal loop test. In the internal loop test, self loop is established in the switching chip to locate the chip failure which is related to the port.

After you use the shutdown command on a port, the port cannot run loopback test. You cannot use the speed, duplex, mdi and shutdown commands on the ports running loopback test. Some ports do not support loopback test, and corresponding prompts will be given when you perform loopback test on them.

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3Com WX3000 Configuring the Ethernet Port to Run Loopback Test, Loopback-detection per-vlan, Loopback external internal