Campus Switching and Routing

Occasional Contributor I

Affect of enabling bpdu-filter



The description of bpdu-filter states:


'Stop a specific port or ports from transmitting BPDUs, receiving BPDUs, and assume a continuous fowarding state.'


(Note the typo in forwarding)


Am I correct in assuming that if two ports are connected together that have bpdu-filter are enabled, neither of them will go into a blocking state and would cause a loop?


What would be the best practice for STP and edge ports?



Contributor II

Re: Affect of enabling bpdu-filter

If you want a port to go in Err disable state on receiving BPDU, you need to go for BPDU guard.

The configuration will look like:

interface Gi 0/0

spanning-tree bpduguard

You can refer here for config example:


On the other hand, bpfu filter operates differently in two modes:

Unconditional BPDU Filter
Unconditionally filter in-bound and out-bound BPDUs. If unconditional BPDU filter is enabled BPDUs are not sent through the port and BPDUs are received but dropped. Unconditional BPDU filter do not depend on portfast enabled/disabled on the port.
Conditional BPDU Filter
When portfast is enabled minimum number of BPDUs are sent to determine if the port is genuinely an edge port then stop sending BPDUs. If BPDUs are received remove portfast state and treat as non-edge port. BPDU filter is also disabled on receipt of BPDUs along with portfast. This filter will be effective only when portfast is enabled.

You can refer here for config example:

Jibran Aziz
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