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BPDU Guard Errors On 3750

We turned on BPDU and now ports will go disabled stating BPDU Guard disabled. I know there is no switch plugged into these ports, and there is no physical loop these ports have either pc's or server plugged into them. Why else could this be happening and how can we resolve this?

Thanks for any help.

Cisco Employee

Re: BPDU Guard Errors On 3750

Hi Am,

Can you confirm if you have portfast enabled on these interfaces? Also can you paste the output of "sh run int " on which you have configured bpdu guard?



Community Member

Re: BPDU Guard Errors On 3750

Yes, portfast is enabled. Here is the results

78LINE#sh run int fastethernet 1/0/10

Building configuration...

Current configuration : 66 bytes


interface FastEthernet1/0/10

spanning-tree portfast trunk


Re: BPDU Guard Errors On 3750

What is connected to the ports? BAsically BPDU guard putting the ports err-disable means the switch thinks it has seen a BPDU.

Some end systems (I am thinking mainly XP here, as other systems that can do it tend to be used more by knowledgable people) can be configured to bridge.

Community Member

Re: BPDU Guard Errors On 3750

It is all XP pc's and HP Printers, and a few HP Proliant Server connected to the ports.

Re: BPDU Guard Errors On 3750

Do printer ports come up with err-disable too?

In the cse of XP, go to a printer connected to a port that goes err-disable and check its network config for bridging.

Re: BPDU Guard Errors On 3750

Sorry typo - I meant go to an XP PC, NOT a printer.

As an afterthought, do the printers have some form of built in switch to allow connection sharing?

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