cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
515
Views
0
Helpful
2
Replies

STP Bpdu filter

feroz syed
Participant
Participant

Hi

i have some confusion with Bpdu filter, when we configure bpdu filter  on seperate portfast enabled port it will filter outgoing bpdu and incoming bpdu (no stp).

If we we configure bpdu filter gobally it enable portfast feature on all port with bpdu filter, if any port receive bpdu message the port lose both filter and portfast state and act like normal stp port

Please correct me if am wrong.

2 ACCEPTED SOLUTIONS

Accepted Solutions

mudasir05
Beginner
Beginner

 

Hello Feroz,

so far as my understanding goes ur absolutely right.

BPDUfilter when enabled on an interface just filters BPDUs in both directions, which effectively disables STP on the port.Bpdu filter will prevent inbound and outbound bpdu but will remove portfast state on a port if a bpdu is received.Enabling BPDU filtering on an interface is the same as disabling spanning tree on it and can result in spanning-tree loops.

when (spanning-tree portfast bpdu-filter default) enabled Globally , an STP port enabled with portfast is not assumed to recieve BPDUs, However, if for any reason the port recieves BPDUs, the Port shall go into (Blocking , listening , learning and then Forwarding state ) and the port will be subject to noramal STP calculations whether being in forwarding or blocking state.

View solution in original post

dragos_sony
Beginner
Beginner

hope it helps

 

https://supportforums.cisco.com/document/45136/importance-bpdu-guard-and-bpdu-filter

 

View solution in original post

2 REPLIES 2

mudasir05
Beginner
Beginner

 

Hello Feroz,

so far as my understanding goes ur absolutely right.

BPDUfilter when enabled on an interface just filters BPDUs in both directions, which effectively disables STP on the port.Bpdu filter will prevent inbound and outbound bpdu but will remove portfast state on a port if a bpdu is received.Enabling BPDU filtering on an interface is the same as disabling spanning tree on it and can result in spanning-tree loops.

when (spanning-tree portfast bpdu-filter default) enabled Globally , an STP port enabled with portfast is not assumed to recieve BPDUs, However, if for any reason the port recieves BPDUs, the Port shall go into (Blocking , listening , learning and then Forwarding state ) and the port will be subject to noramal STP calculations whether being in forwarding or blocking state.

dragos_sony
Beginner
Beginner

hope it helps

 

https://supportforums.cisco.com/document/45136/importance-bpdu-guard-and-bpdu-filter

 

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: