BPDU Guard, will block a port as soon as it detects Spanning Tree packets (BPDU).
This means in practice, when a managed switch with Spanning-Tree protocol is connected, and it's not a FortiSwitch, it will shutdown the port.
Clients should not send spanning-tree packets.
It's a per port setting and can be enabled in the GUI:
In the CLI it's possible to change the bpdu-guard timeout from the default 5min value to another:
config switch-controller managed-switch
edit <switch-id>
config ports
edit <port>
set stp-bpdu-guard enabled
set stp-bpdu-guard-timeout <mins>
next
end
next
end
