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BPDUFILTER Vs BPDUGUARD clarifications

Hi all

I understand teh use of these commands as per the cisco and various other documents. However, there are still few unclear spots.

1-When filter option is ebnabled on port level, teh port is no longer part of SPT and BPDU's are filtered ( In/out). If u receive a BPDU from a misconfigured device, port looses it's portfast status...but why does is this happen in 1st place if BPDU's are filtered ?

2-Once BPDUs are received and portfast status lost, do u then keep on receiving BPDUs...unless Guard option is on to disable the port ?

3-On RSTP, and edge port is on portfast, what happens when the port receives a BPDU and filter is on. What show i see in spanning -tree port definition P2P ?

Links would be great, the existing ones are a repeat of main definition and guidelines of the command.

TIA

Sam

It is obvious that Filter on its own is not enough.

1 REPLY
Silver

Re: BPDUFILTER Vs BPDUGUARD clarifications

"spanning-tree portfast bpdufilter default" is the global command to stop

STP BPDU processing and would result in that port not sending any BPDU nor

receiving it.

"spanning-tree portfast bpduguard" however is the global command to

err-disable the port when it receives a BPDU.

Hence, they are both mutually exclusive! If you use bpdufilter then you

cannot use bpduguard on the same port as that port will not receive (i.e.

drop received bpdu).

check out the following link for more info :

http://www.cisco.com/en/US/products/hw/switches/ps5528/products_configuration_guide_chapter09186a00801e85e3.html#1032048

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