H3C S5100-SI

1-5
Configuring Loopback Detection for an Ethernet Port
Loopback detection is used to monitor if loopback occurs on a switch port.
After you enable loopback detection on Ethernet ports, the switch can monitor if external loopback
occurs on them. If there is a loopback port found, the switch will put it under control.
z 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.
z 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.
Follow these steps to configure loopback detection for an Ethernet port:
To do... Use the 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.
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.