You can enable the root guard on a per-port basis. If enabled on a port, the switch ignores superior BPDUs received on that port and blocks that port. The port reverts back to the forwarding state automatically after the port stops receiving superior BPDUs. You must configure the port as a trunk port before you enable the root guard on the interface. By default, the root guard is disabled.
SEFOS# configure terminal SEFOS(config)# interface extreme-ethernet 0/1
SEFOS(config-if)# switchport mode trunk
SEFOS(config-if)# spanning-tree guard root SEFOS(config-if)# end
SEFOS# show spanning-tree interface extreme-ethernet 0/1 rootguard Root Guard is Enabled
SEFOS# configure terminal SEFOS(config)# interface extreme-ethernet 0/1 SEFOS(config-if)# no spanning-tree guard SEFOS(config)# end TOR-1 SEFOS#