3com 4210 PWR 9-Port 3CR17341-91-ME User Manual

Product codes
3CR17341-91-ME
Page of 567
Ethernet Port Configuration
101
If loopback is found on an access port, the system disables the port, sends a 
Trap message to the client and removes the corresponding MAC forwarding 
entry.
If loopback is found on a trunk or hybrid port, the system sends a Trap message 
to the client. When the loopback port control function is enabled on these 
ports, the system disables the port, sends a Trap message to the client and 
removes the corresponding MAC forwarding entry.
CAUTION:
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.
Enabling 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.
Table 64   Configure loopback detection for an Ethernet port
Operation 
Command 
Remarks 
Enter system view 
system-view 
Enable loopback detection 
globally 
loopback-detection enable  Required
By default, loopback 
detection is disabled globally. 
Set the interval for performing 
port loopback detection 
loopback-detection 
interval-time
 time 
Optional
The default is 30 seconds. 
Enter Ethernet port view 
interface interface-type 
interface-number
 
Enable loopback detection on 
a specified port 
loopback-detection enable  Required
By default, port loopback 
detection is disabled. 
Enable loopback port control 
on the trunk or hybrid port 
loopback-detection control 
enable
 
Optional
By default, loopback port 
control is not enabled. 
Configure the system to run 
loopback detection on all 
VLANs of the current trunk or 
hybrid port 
loopback-detection 
per-vlan enable
 
Optional
By default, the system runs 
loopback detection only on 
the default VLAN of the 
current trunk or hybrid port.
Table 65   Enable loopback test
Operation 
Command 
Remarks 
Enter system view 
system-view 
Enter Ethernet port view 
interface interface-type 
interface-number
 
Enable loopback test 
loopback { external | 
internal } 
Optional