Enabling loop guard – H3C Technologies H3C WX3000E Series Wireless Switches User Manual
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Step Command
Remarks
2.
Enter interface view or port
group view.
•
Enter Ethernet interface view:
interface interface-type
interface-number
•
Enter port group view:
port-group manual port-group-name
Use either command.
3.
Enable the root guard function
for the ports.
stp root-protection
Disabled by default.
NOTE:
Among loop guard, root guard, and edge port settings, only one function (whichever is configured the
earliest) can take effect on a port at the same time.
Enabling loop guard
By keeping receiving BPDUs from the upstream device, a device can maintain the state of the root port
and blocked ports. However, due to link congestion or unidirectional link failures, these ports may fail to
receive BPDUs from the upstream devices. The device reselects the port roles: Those ports in forwarding
state that failed to receive upstream BPDUs become designated ports, and the blocked ports transition to
the forwarding state, resulting in loops in the switched network. The loop guard function can suppress the
occurrence of such loops.
The initial state of a loop guard-enabled port is discarding in every MSTI. When the port receives BPDUs,
its state transitions normally. Otherwise, it stays in discarding state to prevent temporary loops.
Make this configuration on the root port and alternate ports of a device.
To enable loop guard:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Enter interface view or port
group view.
•
Enter Ethernet interface view:
interface interface-type
interface-number
•
Enter port group view:
port-group manual
port-group-name
Use either command.
3.
Enable the loop guard function
for the ports.
stp loop-protection
Disabled by default.
NOTE:
•
Do not enable loop guard on a port connecting user terminals. Otherwise, the port stays in discarding
state in all MSTIs because it cannot receive BPDUs.
•
Among loop guard, root guard and edge port settings, only one function (whichever is configured the
earliest) can take effect on a port at the same time.