When BPDU Guard is enabled globally on a switch it affects all ports that are configured as portfast
ports. By default
BPDU Guard is disabled, when you configure BPDU Guard on interface that port doesn't have to be configured
as a porfast port.
If a BPDU is received on that port it will be error disabled.
So BPDU Guard disables a port of any BPDUs received on the port.
If you configure it BPDU Guard on the port.
This is very useful
once again where ports should have PCs connected to them and not another switch. When enabled
globally on a switch, BPDU Guard prevents problems with portfast ports, portfast should only be enabled
on access ports connected to user devices and not to switches.
When BPDU Guard is enabled globally and a port is then configured as a portfast port and it receives
a BPDU the port is error disabled.