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1151 Views 5 Replies Latest reply: May 4, 2012 3:36 AM by Lorenzo RSS

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BPDU Guard issue....

Jan 22, 2012 10:02 AM

Jimmy Sands 644 posts since
May 7, 2009

I was trying to understand bpduguard, I put fa0/1 on SW1 as spanning-portfast, never went down.  I put bpduguard on int, never went down, I sh/no shut the int and got this:

 

*Mar  1 01:39:21.943: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port Fa0/1 with BPDU Guard enabled. Disabling port.

*Mar  1 01:39:21.943: %PM-4-ERR_DISABLE: bpduguard error detected on Fa0/1, putting Fa0/1 in err-disable state

 

Why did it take a sh/no shut to bring about this error?

 

 

 

  • Paul Stewart  -  CCIE Security 7,570 posts since
    Jul 18, 2008
    Currently Being Moderated
    1. Jan 22, 2012 10:19 AM (in response to Jimmy Sands)
    Re: BPDU Guard issue....

    While it was a trunk, it wasn't an access port. You added portfast after the fact, then added bpdu guard.  BPDUGuard doesn't work unless the port is operationally in portfast mode (which isn't usually the case for a trunk).  When you shut, no shut the port, it initially came up in portfast.  It would lose its portfast status when it receives the first BPDU.  But this time, BPDUGuard is enabled, so it would err-disable the port instead. 

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  • Lorenzo 2 posts since
    May 4, 2012
    Currently Being Moderated
    Re: BPDU Guard issue....

    hi guys, I have the same problem on the f0/1 port gets disabled when i connect an access point, is there away in which I can prevent this from happening and also keep my port on PoE?

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  • El Tigre 108 posts since
    Jan 20, 2012
    Currently Being Moderated
    4. May 4, 2012 2:25 AM (in response to Lorenzo)
    Re: BPDU Guard issue....

    Hi Lorenzo,

    What kind of Access Point?   Cisco?

     

    These are some basic commands I have used for AP's (and then add qos).

     

    switch(config)  interface f0/1

    switch(config-if)#  switchport trunk encapsulation dot1q

    switch(config-if)#  switchport mode trunk

    switch(config-if)#  switchport trunk allowed vlan  xxx, xx

    switch(config-if)#  spanning-tree portfast trunk


    BUT, I have never applied bpduguard to an AP.  

    bpduguard is suppose to errdisable the port if it gets bpdus.

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  • Lorenzo 2 posts since
    May 4, 2012
    Currently Being Moderated
    5. May 4, 2012 3:36 AM (in response to El Tigre)
    Re: BPDU Guard issue....

    Thanks for your respond, I will try the commands above, the name of the AP WAP200 wireless-G access point, and the name of the switch 2960 PoE 48 port.

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