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Cisco switch

Please help me w/ this multiple choice question:
What is the effect of this confi command?
spanning-tree portfast bpdufilter default

A. If BPDUs are received by a port configured for PortFast, they are ignored and none is sent.
B. The command will enable BPDU filtering on all ports regardless of whether they are configured for BPDU filtering at interface level
C. If BPDUs are received by port configured for portfast, the port will transition to forwarding state
D. If BPDUs are received by port configured for portfast, then portfast is desabled and BPDUs are processed normally.
E. None of alternatives apply.
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totaram
Asked:
totaram
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1 Solution
 
Don JohnstonInstructorCommented:
E
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totaramAuthor Commented:
I am told that answer is D. Don't know how?
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Don JohnstonInstructorCommented:
The global BPDU filter command disables the transmission of BPDUs on all ports which have portfast configured. None of the available commands meet that criteria. So E is correct.
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Don JohnstonInstructorCommented:
Just reread the answers and you're right. D is correct. I was approaching the question from a different direction.
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jamalosCommented:
Why D is correct ?

Can you explain please as I found in Cisco document that BPDU filer put the port on disable state if BPDU is received!!!!!

Thanks
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Don JohnstonInstructorCommented:
Portfast makes the port skip the initial listening/learning process. Adding BPDU filter causes it to not send BPDUs.

If a BPDU is received on a port then the portfast/BPDU filter behavior is suspended but the port is still operational.

I think you're referring to BPDU guard. That will disable a port if a BPDU is received.
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jamalosCommented:
you're right I understood wrong this topic, in fact If BPDUs are seen, the port looses its PortFast status, BPDU filtering is disabled, and STP resumes default operation on the port,

I thought that was the port who is disabled..... :) but I was wrong :)
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