BPDU Filtering
BPDU filtering is another way of preventing loops in the network. It also can
be enabled either globally or at the interface, and it functions differently at
each. In global configuration, if a Portfast interface receives any BPDUs, it is
taken out of Portfast status. At interface configuration mode, it prevents the
port from sending or receiving BPDUs. The commands are:
Switch(config)#spanning-tree portfast bpdufilter default
Switch(config-if)#spanning-tree bpdufilter enable