spanning-tree bpduguard enable
Shut the port down if it receives a BPDU — protects PortFast ports.
Configuration-only in this lab: no device here sends rogue BPDUs, so the port is never err-disabled by it. It stays in running-config so real configs round-trip. Port-security IS enforced if you need a port that really shuts.
Don't just read it — type spanning-tree bpduguard enable in a real network simulator in your browser and watch it take effect. No install, no account needed to start.
Frequently asked
What does the "spanning-tree bpduguard enable" command do?
Shut the port down if it receives a BPDU — protects PortFast ports.
What's the common gotcha with "spanning-tree bpduguard enable"?
Configuration-only in this lab: no device here sends rogue BPDUs, so the port is never err-disabled by it. It stays in running-config so real configs round-trip. Port-security IS enforced if you need a port that really shuts.