HP 5820X Series

90
the link connected to this port in the MSTI). If the port receives no BPDUs with a higher priority within
twice the forwarding delay, it will revert to its original state.
Make this configuration on a designated port.
To enable root guard:
To do... Use the command... Remarks
1. Enter system view
system-view —
Enter Ethernet interface
view or Layer 2 aggregate
interface view
interface interface-type
interface-number
2. Enter
interface
view or port
group view
Enter port group view
port-group manual port-
group-name
Required.
Use either command.
3. Enable the root guard function for the
ports
stp root-protection
Required.
Disabled by default.
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, because of link congestion or unidirectional link failures, these ports may
fail to receive BPDUs from the upstream devices. The device will reselect the port roles: Those ports in
forwarding state that failed to receive upstream BPDUs will become designated ports, and the blocked
ports will 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 the discarding state to prevent temporary loops.
Make this configuration on the root port and alternate ports of a device.
To enable loop guard:
To do... Use the command... Remarks
1. Enter system view
system-view —
Enter Ethernet interface view
or Layer 2 aggregate
interface view
interface interface-type
interface-number
2. Enter
interface
view or port
group view
Enter port group view
port-group manual port-
group-name
Required.
Use either command.
3. Enable the loop guard function for the ports
stp loop-protection
Required.
Disabled by default.
Do not enable loop guard on a port connecting user terminals. Otherwise, the port will stay in the
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.