3com WX3000 Manuel D’Utilisation

 

1-10 

Configure the system to run 
loopback detection on all 
VLANs for the trunk and hybrid 
ports  

Optional 

By default, the system runs 
loopback detection only on the 
default VLAN for the trunk and 
hybrid ports.  

 

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.  

z 

After you use the undo loopback-detection enable command in system view, loopback detection 

will be disabled on all ports.  

z 

The commands of loopback detection feature cannot be configured with the commands of port link 

aggregation at the same time. 

 

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:  

Enter system view  

— 

Enter Ethernet port view  

interface interface-type 
interface-number 

— 

Configure the Ethernet port to run 
loopback test  

loopback { external | internal } 

Required 

 

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.  

z 

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.