BPDU Filter prevents BPDUs from being sent on an interface. This essentially disables STP on this interface. It also ignores any incoming BPDUs on the interface. This is rarely needed so it is likely you will never see it in a production network. You can use this in situations where you want a switch to connect to that port, but you don’t want it to participate in STP.

This feature works differently depending on if it is enabled globally or on a particular interface:

  • Global: if you enable BPDUfilter globally then any interface with portfast enabled will not send or receive any BPDUs. When you receive a BPDU on a portfast enabled interface then it will lose its portfast status, disables BPDU filtering and acts as a normal interface.
  • Interface: if you enable BPDUfilter on the interface it will ignore incoming BPDUs and it will not send any BPDUs. This is the equivalent of disabling spanning-tree.

For additional STP fine tuning features, take a look at STP fine tuning the spanning tree protocol.