3com 5500-ei pwr Installation Instruction

 

1-6 

detection 
on a 
specified 
port 

Enable the loopback port 
auto-shutdown function 

Optional 

By default, the loopback port 
auto-shutdown function is enabled on 
ports if the device boots with the default 
configuration file (config.def);  

By default, this function is disabled if 
the device boots with null configuration

Enable loopback port 
control on the trunk or 
hybrid port  

Optional 

By default, the loopback port control 
function is enabled on ports if the 
device boots with the default 
configuration file (config.def);  

By default, this function is disabled if 
the device boots with null configuration

Configure the system to 
run loopback detection 
on all VLANs of the 
current trunk or hybrid 
port  

Optional 

By default, the system runs loopback 
detection only on the default VLAN of 
the current trunk or hybrid port. 

 

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  loopback-detection control enable command  and the loopback-detection per-vlan 

enable command are not applicable to access ports. When the link type of a non-access port 

changes to access, the two commands already configured on the port become invalid 

automatically.  

 

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 enable loopback test: 

Enter system view  

— 

Enter Ethernet port view  

interface interface-type interface-number 

— 

Enable loopback test  

loopback { external | internal } 

Required