Loopback-Detection Enable - HP 6600 Command Reference Manual

Usage guidelines
When a hybrid or trunk port detects a loop condition, it sends traps, whether loopback detection control
is enabled or not. However, the port performs the protective action that you configure with the
loopback-detection action command only after loopback detection control is enabled.
This command is not applicable to access ports.
Examples
# Enable loopback detection control on the trunk port GigabitEthernet 4/0/1.
<Sysname> system-view
[Sysname] loopback-detection enable
[Sysname] interface gigabitethernet 4/0/1
[Sysname-GigabitEthernet4/0/1] port link-type trunk
[Sysname-GigabitEthernet4/0/1] loopback-detection enable
[Sysname-GigabitEthernet4/0/1] loopback-detection control enable

loopback-detection enable

Use loopback-detection enable to enable loopback detection globally in system view or on interfaces in
Ethernet interface or port group view. To use loopback detection on an Ethernet interface, you must
enable the function both globally and on the port.
Use undo loopback-detection enable to disable loopback detection globally or on Ethernet interfaces.
Syntax
loopback-detection enable
undo loopback-detection enable
Default
Loopback detection is disabled on all Ethernet interfaces.
Views
System view, Layer 2 Ethernet interface view, port group view
Default command level
2: System level
Usage guidelines
The undo loopback-detection enable command in system view disables loopback detection on all
interfaces.
If an interface receives a packet that it sent out, a loop has occurred. Loops might cause broadcast storms,
which degrade network performance. 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 (for example, shut down the port) when a loop is detected.
In addition to the configured protective action, the device also performs other actions to alleviate the
impact of the loops. For more information, see Table 12.
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