BPDU Filter hides STP on a port — it solves no loop problem and can create one.

• Global form: PortFast ports send briefly at link-up and re-enable STP if a BPDU arrives (fail-safe).
• Per-port form: no sends, ignores receives — STP effectively off on that port.
• Legit uses: ISP handoffs, controlled labs. On any redundant link: loop factory.

One-liner: BPDU Filter hides STP — it protects nothing.