Quick Definition
Shuts down a PortFast-enabled port if it receives a BPDU, protecting the spanning tree.
BPDU Guard protects access ports configured with PortFast. If a port with BPDU Guard receives a BPDU (from a rogue switch or misconfigured device), BPDU Guard immediately puts the port into an errdisabled state and shuts it down. This prevents a rogue switch from affecting the spanning tree topology. An errdisabled port must be manually recovered with 'shutdown' followed by 'no shutdown', or auto-recovery can be configured.
interface GigabitEthernet0/1 spanning-tree bpduguard enable spanning-tree portfast bpduguard default ! global
BPDU Guard puts the port in errdisabled state, not just blocking. An errdisabled port shows 'err-disabled' in the interface status and must be manually or automatically re-enabled.
A Layer 2 loop-prevention protocol that blocks redundant paths in a switched network.
The STP control frames that switches exchange to elect the Root Bridge and maintain the spanning tree.
An STP feature that bypasses the Listening and Learning states on access ports, putting them immediately into Forwarding.
Prevents a port from becoming the Root Port, protecting the Root Bridge position.
BPDU Guard protects access ports configured with PortFast. If a port with BPDU Guard receives a BPDU (from a rogue switch or misconfigured device), BPDU Guard immediately puts the port into an errdisabled state and shuts it down. This prevents a rogue switch from affecting the spanning tree topology. An errdisabled port must be manually recovered with 'shutdown' followed by 'no shutdown', or auto-recovery can be configured.
BPDU Guard puts the port in errdisabled state, not just blocking. An errdisabled port shows 'err-disabled' in the interface status and must be manually or automatically re-enabled.
BPDU Guard falls under the Spanning Tree domain of the 200-301 exam. Understanding it in context with related terms like stp and portfast is essential for answering scenario-based questions correctly.