Enabling BPDU Filter

BPDU Filter feature of STP is concerned with stopping the transmission and reception of BPDUs on a port. It can be activated globally or per interface basis. It's behavior differs depending on how it is activated..

Globally - 

S(config)#spanning-tree portfast bpdufilter default

If configured globally, it applies only to Edge ports (PortFast configured ports).

When an edge port becomes up, they start sending BPDUs each Hello interval and send 11 BPDUs..

If no BPDU is received from the neighboring device, the port will stop sending BPDUs..

But during this 10 Hello intervals or anytime after that, if a BPDU is received, BPDU Filter operation will be stopped and process the BPDU as a normal STP port. 

What really happens is that when a BPDU is received on an Edge port, the Edge port status is lost (behavior of PortFast) and treated as a normal STP port. Because the BPDU Filter is applied to Edge ports only when configured globally, BPDU Filter function is automatically stopped.

Per Interface Basis -

S(config-if)#spanning-tree bpdufilter enable

If configured in interface level, BPDU Filter will cause the port to stop sending and receiving BPDUs from that port. No matter Edge port or else..

This can cause switching loops accidentally if plugged to switches.

Now let's see an actual topology where these 2 are configured.

Here are the results of the above configuration.

Now let's see what happens when I disable the BPDU Filter on Fa0/2 interface on SW-2..
After sometime I could see the green LED turns amber on Fa0/2 on SW-2..

Now you can see the port on SW-2 has started sending and receiving BPDUs and the Edge status has gone on Fa0/2 of SW-1 and from SW-2's side it has become an Alternate port as expected..