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[Sysname-GigabitEthernet1/0/1] loopback internal
Loop internal succeeded!
loopback-detection action
Syntax
loopback-detection action { no-learning | semi-block | shutdown }
undo loopback-detection action
View
Ethernet interface view, port group view
Default level
2: System level
Parameters
no-learning: Disables MAC address learning on the interface.
semi-block: Blocks all packets but STP BPDUs.
shutdown: Shuts down the Ethernet interface. To bring up the interface again, use the undo shutdown
command.
Description
Use the loopback-detection action command to configure the action for loop protection on Ethernet
interfaces.
Use the undo loopback-detection action command to restore the default.
By default, a looped interface discards all incoming packets but still forwards outgoing packets; the
system generates traps and deletes all MAC address entries of the looped interface.
After 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 the chapter “VLAN configuration commands.”
Configure Ethernet interfaces one by one in Ethernet interface view or in bulk in port group view.
Examples
# Configure access port GigabitEthernet 1/0/1 to shut down when a loop is detected.
<Sysname> system-view
[Sysname] loopback-detection enable
[Sysname] interface gigabitethernet 1/0/1
[Sysname-GigabitEthernet1/0/1] loopback-detection enable
[Sysname-GigabitEthernet1/0/1] loopback-detection action shutdown
# Configure trunk port GigabitEthernet 1/0/2 to shut down when a loop is detected.
<Sysname> system-view
[Sysname] loopback-detection enable
[Sysname] interface gigabitethernet 1/0/2
[Sysname-GigabitEthernet1/0/2] port link-type trunk
[Sysname-GigabitEthernet1/0/2] loopback-detection enable
[Sysname-GigabitEthernet1/0/2] loopback-detection control enable
[Sysname-GigabitEthernet1/0/2] loopback-detection action shutdown
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