H3C Technologies H3C S10500 Series Switches - Manual (Page 24)

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Figure 5 Multi-port loopback
You can enable loopback detection to detect loops on an interface and, if the interface supports the
loopback-detection action command, configure the protective action to take on the receiving interface
when a loop is detected, for example, to shut down the interface. Depending on whether a protective
action is configured, the switch takes the actions in Table 1 to alleviate the impact of the loop condition.
Table 1 Actions to take upon detection of a loop condition
Actions
Port type
No protective action is configured A protective action is configured
Access port
• Place the receiving interface in controlled mode.
The interface does not receive or send packets.
• Generate traps.
• Delete all MAC address entries of the interface.
• Perform the configured protective
action.
• Generate traps and log
messages.
• Delete all MAC address entries
of the interface.
Hybrid or trunk
port
• Generate traps.
• 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.
• Create 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.
Follow these steps to configure loopback detection:
To do… Use the command… Remarks
Enter system view system-view —
Enable global loopback
detection
loopback-detection enable
Required
Disabled by default.
Enable multi-port
loopback detection loopback-detection
multi-port-mode enable
Optional
By default, multi-port loopback detection is
disabled, and the switch can only detect
single-port loopback.
Set the loopback
detection interval loopback-detection interval-time
time Optional
30 seconds by default.