3Com 4200G 12-Port Configuration Manual page 86

72 C 14: B
HAPTER ASIC
Setting Loopback
Detection for an
Ethernet Port
Configuring the
Ethernet Port to Run
Loopback Test
P C
ORT ONFIGURATION
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.
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 54 Set loopback detection for an Ethernet port
Operation
Enter system view
Enable loopback detection
globally
Set time interval for 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 for the trunk and
hybrid ports
Display port loopback
detection information
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.
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.
Table 55 Configure the Ethernet port to run loopback test
Operation
Enter system view
Enter Ethernet port view
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
display loopback-detection
Command
system-view
interface interface-type interface-number
Remarks
—
Optional
By default, loopback detection is
disabled globally.
Optional
The default interval is 30 seconds.
—
Optional
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 for the trunk and
hybrid ports.
Optional
You can use the command in any
view.
Remarks
—
—