BPDU Filter

Sections:

• Lab Topology
• Configuration

Overview: 

• BPDU Filtering helps to prevent and eliminate BPDUs from being sent or received on specific ports
• By filtering or blocking BPDUs, BPDU Filtering prevents certain switches from participating in the STP process
• Useful in scenarios where you don't want a device to influence the STP topology

How it Works:

• When BPDU Filtering is enabled, the switch will block BPDUs from being forwarded out of the filtered port, nor will it receive BPDUs from that port
• BPDU Filtering essentially makes the port behave as if it’s not participating in STP

When to use: 

• Suitable for edge/portfast ports or where STP is not needed or desired to prevent potential STP loops 
• BPDU Filtering can be used on ports connecting to other switches not meant to participate in STP to ensure they don't interfere with the network's STP topology
• Cases where the switch port should be in a permanent forwarding state by the administrator 

Lab Topology

Scenario:

• Goal is to enable BPDU Filter on interface Gi3/3 of the AccessSW1 towards the client PC
• Since end client devices do not understand STP BPDUs there is no need to waste bandwidth sending out BPDUs towards the PC as these BPDUs received from the switch will only be discarded

BPDU Filtering Configuration

Port Gi3/3 sending out BPDUs towards the client PC before BPDU Filtering implementation.

Configuring BPDU-Filter on interface Gi3/3.

Cycled port Gi3/3 to reset the BPDU counter - After implementation, BPDUs sent counter remains at '0'.