Configuration procedure
Configure Device A:
# Create VLAN 100, and globally enable loop detection for the VLAN.
<DeviceA> system-view [DeviceA] vlan 100 [DeviceA-vlan100] quit [DeviceA] loopback-detection global enable vlan 100
# Configure Ten-GigabitEthernet 1/0/1 and Ten-GigabitEthernet 1/0/2 as trunk ports, and assign them to VLAN 100.
[DeviceA] interface ten-gigabitethernet 1/0/1 [DeviceA-Ten-GigabitEthernet1/0/1] port link-type trunk [DeviceA-Ten-GigabitEthernet1/0/1] port trunk permit vlan 100 [DeviceA-Ten-GigabitEthernet1/0/1] quit [DeviceA] interface ten-gigabitethernet 1/0/2 [DeviceA-Ten-GigabitEthernet1/0/2] port link-type trunk [DeviceA-Ten-GigabitEthernet1/0/2] port trunk permit vlan 100 [DeviceA-Ten-GigabitEthernet1/0/2] quit
# Configure the global loop protection action as shutdown.
[DeviceA] loopback-detection global action shutdown
# Set the loop detection interval to 35 seconds.
[DeviceA] loopback-detection interval-time 35
Configure Device B:
# Create VLAN 100.
<DeviceB> system-view [DeviceB] vlan 100 [DeviceB–vlan100] quit
# Configure Ten-GigabitEthernet 1/0/1 and Ten-GigabitEthernet 1/0/2 as trunk ports, and assign them to VLAN 100.
[DeviceB] interface ten-gigabitethernet 1/0/1 [DeviceB-Ten-GigabitEthernet1/0/1] port link-type trunk [DeviceB-Ten-GigabitEthernet1/0/1] port trunk permit vlan 100 [DeviceB-Ten-GigabitEthernet1/0/1] quit [DeviceB] interface ten-gigabitethernet 1/0/2 [DeviceB-Ten-GigabitEthernet1/0/2] port link-type trunk [DeviceB-Ten-GigabitEthernet1/0/2] port trunk permit vlan 100 [DeviceB-Ten-GigabitEthernet1/0/2] quit
Configure Device C:
# Create VLAN 100.
<DeviceC> system-view [DeviceC] vlan 100 [DeviceC–vlan100] quit
# Configure Ten-GigabitEthernet 1/0/1 and Ten-GigabitEthernet 1/0/2 as trunk ports, and assign them to VLAN 100.
[DeviceC] interface ten-gigabitethernet 1/0/1 [DeviceC-Ten-GigabitEthernet1/0/1] port link-type trunk [DeviceC-Ten-GigabitEthernet1/0/1] port trunk permit vlan 100 [DeviceC-Ten-GigabitEthernet1/0/1] quit [DeviceC] interface ten-gigabitethernet 1/0/2 [DeviceC-Ten-GigabitEthernet1/0/2] port link-type trunk [DeviceC-Ten-GigabitEthernet1/0/2] port trunk permit vlan 100 [DeviceC-Ten-GigabitEthernet1/0/2] quit