STP loopguard taking effect

[chrisc100]

Hello

Does STP loopguard configuration take effect immediately or does STP instance need to be restarted?

We disabled loopguard on a port since the link we are moving to does not support STP, however the vlan still got blocked:

interface GigabitEthernet1/0/22

no spanning-tree guard loop

switchport trunk allowed vlan 1,2
switchport mode trunk
switchport nonegotiate
spanning-tree portfast trunk
spanning-tree bpduguard disable
spanning-tree link-type point-to-point

Jul 10 2021 07:12:03.818 CET: %SPANTREE-2-LOOPGUARD_BLOCK: Loop guard blocking port GigabitEthernet1/0/22 on VLAN0001.

Platform is 9300, is this a bug?

Thanks in advance.

[marce1000]

 - Could you remove spanning-tree portfast trunk  , shut/no-shut the port afterwards, see what happens.

 M.

[Giuseppe Larosa]

Hello @chrisc100 ,

try to use default interface giga1/0/22 and reconfigure it .

Have you got spanning-tree loop guard enabled at global level ?

I don't recommend it.

It is better to have it disabled at global level and to enable it on selected ports going to other switches that are more near to the root bridge,  as the feature is triggered by the lack of reception of STP BPDUs on a non designated port.

In your case if the other device does not execute STP this port should become designated.

Also a shut / no shut cycle can help in restarting the STP state machine.

Hope to help

Giuseppe