3Com 4210 PWR Configuration Manual page 103

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Enabling Loopback Test
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.
Table 64 Configure loopback detection for an Ethernet port
Operation
Enter system view
Enable loopback detection
globally
Set the interval for performing
port loopback detection
Enter Ethernet port view
Enable loopback detection on
a specified port
Enable loopback port control
on the trunk or hybrid port
Configure the system to run
loopback detection on all
VLANs of the current trunk or
hybrid port
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.
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 65 Enable loopback test
Operation
Enter system view
Enter Ethernet port view
Enable loopback test
Command
system-view
loopback-detection enable
loopback-detection
interval-time time
interface interface-type
interface-number
loopback-detection enable
loopback-detection control
enable
loopback-detection
per-vlan enable
Command
system-view
interface interface-type
interface-number
loopback { external |
internal }
Ethernet Port Configuration
Remarks
-
Required
By default, loopback
detection is disabled globally.
Optional
The default is 30 seconds.
-
Required
By default, port loopback
detection is disabled.
Optional
By default, loopback port
control is not enabled.
Optional
By default, the system runs
loopback detection only on
the default VLAN of the
current trunk or hybrid port.
Remarks
-
-
Optional
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