Table 1 Actions to take upon detection of a loop condition
Port type
Access port
Hybrid or
trunk port
Configuration restrictions and guidelines
•
To use loopback detection on an Ethernet interface, you must enable the function both globally
and on the interface.
•
When you enable multi-port loopback detection on a switch, both single-port and multi-port
loops can be detected.
•
To disable loopback detection on all interfaces, run the undo loopback-detection enable
command in system view.
•
To enable a hybrid or trunk port to take the administratively specified protective action, you must
use the loopback-detection control enable command on the port.
•
When you change the link type of an Ethernet interface by using the port link-type command,
the switch removes the protective action configured on the interface. For more information
about the port link-type command, see Layer 2—LAN Switching Command Reference.
Configuration procedure
To configure loopback detection:
Step
Enter system view.
1.
Enable global
2.
loopback detection.
Enable multi-port
3.
loopback detection.
Set the loopback
4.
detection interval.
Actions
No protective action is configured
•
Place the receiving interface in controlled
mode. The interface does not receive or
send packets.
•
Generate traps and log messages.
•
Delete all MAC address entries of the
interface.
•
Generate traps and log messages.
•
If loopback detection control is enabled,
place the receiving interface in controlled
mode. The interface does not receive or
send packets.
•
Delete all MAC address entries of the
interface.
Command
system-view
loopback-detection enable
loopback-detection
multi-port-mode enable
loopback-detection
interval-time time
A protective action is configured
•
•
•
•
•
•
Remarks
N/A
Disabled by default.
Optional.
By default, multi-port loopback detection is
disabled, and the device can only detect
single-port loopback.
Optional.
30 seconds by default.
10
Perform the configured protective
action.
Generate traps and log
messages.
Delete all MAC address entries of
the interface.
Generate traps and log
messages.
If loopback detection control is
enabled, take the configured
protective action on the interface.
Delete all MAC address entries of
the interface.