Unexpected BPDU received. Port has been Disabled

[blin]

One of our Cisco 3750G switches keeps showing this warning: Description: Gi4/0/43: Unexpected BPDU received. Port has been Disabled. Recommendation: Check Configuration of the switch, also make sure devices connected to the switch. Enable this port again. However, there is no thing connecting to the port Gi4/0/43 as shown this link: http://www.howtocisco.com/cisco/issues/switcherror1.htm. Why do you get this warning?

[paolo bevilacqua]

How do you "prove" that there isn't anything connected to it ?

[cadet alain]

Hi,

do a sh int  gi0/43 status  it should appear as err-disabled then do a show run int gi0/43 you should see it has bpdu guard enabled or portfast and then  in that case globally with sh run | in spanning you should see it globally enabled for portfast ports.

Hasn't someone been putting a hub or a switch on that port?  do a sh cdp nei and a sh mac-  interface gi0/43

Regards.

[blin]

The link shows the picture and I have double checked it in physical location.

[paolo bevilacqua]

Check "show  int Gi4/0/43" and also your logs, as it's likely something had been connected to the port.

[cadet alain]

ok but could you anyway verify what I told you because when a port is errdisabled then unless you do a shut - no shut it stays that way indefinitely

if you haven't got errdisable recovery cause enabled of course.So someone may have plugged a switch or hub and then moved it because as the port was not usable it was no more interest.

Regards.

[blin]

Thank you for the troubleshooting tips. Here are the results. The switch is located in closet  and someone must have a key to get into it.

BG3750_1-1#sh int  gi4/0/43 status Port      Name              Status      Vlan      Duplex  Speed Type

Gi4/0/43                    err-disabled 1            auto  auto 10/100/1000B seTX BG3750_1-1

#show run int gi4/0/43 Building configuration...

Current configuration : 156 bytes !

interface GigabitEthernet4/0/43

switchport trunk encapsulation dot1q

switchport mode trunk

spanning-tree portfast

spanning-tree bpduguard enable

end

BG3750_1-1#sh cdp nei Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge                   S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone,                   D - Remote, C - CVTA, M - Two-port Mac Relay Device ID        Local Intrfce    Holdtme    Capability  Platform  Port ID ADM_SER_3020_1.chicagobotanic.org                 Gig 1/0/4        153              S I  WS-CBS302 Gig 0/24 ADM_SER_3020_1.chicagobotanic.org                 Gig 1/0/3        153              S I  WS-CBS302 Gig 0/23 ADM_SER_3020_1.chicagobotanic.org                 Gig 1/0/2        153              S I  WS-CBS302 Gig 0/22 ADM_SER_3020_1.chicagobotanic.org                 Gig 1/0/1        153              S I  WS-CBS302 Gig 0/21 ADM_SER_3020_2.chicagobotanic.org                 Gig 3/0/29        174              S I  WS-CBS302 Gig 0/24 ADM_SER_3020_2.chicagobotanic.org                 Gig 3/0/30        174              S I  WS-CBS302 Gig 0/23 ADM_SER_3020_2.chicagobotanic.org                 Gig 3/0/31        174              S I  WS-CBS302 Gig 0/21 ADM_SER_3020_2.chicagobotanic.org                 Gig 3/0/32        174              S I  WS-CBS302 Gig 0/22 ADM_TELE_BASE_3750                 Gig 1/0/49        133              S I  WS-C3750G Gig 1/0/25 GWY_CLOSET_3560_1                 Gig 1/0/51        125              S I  WS-C3560G Gig 0/51 ADM_TELE_2ND_3750 Device ID        Local Intrfce    Holdtme    Capability  Platform  Port ID                 Gig 3/0/49        179              S I  WS-C3750G Gig 1/0/25 ADM_TELE_1ST_3750                 Gig 2/0/49        171              S I  WS-C3750G Gig 1/0/25 ADM_SER_WLC1    Gig 1/0/50        177              H    AIR-WLC44 Unit - 0 Sl t - 0 Port - 1 ADM_SER_WLC1    Gig 1/0/50        177              H    AIR-WLC44 Unit - 0 Sl t - 0 Port - 2 chicagotech-clnt-vis.netops.tmcs                 Gig 3/0/46        156              R    C831      Eth 1

[blin]

Update

I have been monitoring this switch and no one touches the switch. After I ran shut and no shut and sh int  gi0/43 status notconnect. BG3750_1-1#sh int  gi4/0/43 status Port      Name              Status      Vlan      Duplex  Speed Type Gi4/0/43                    notconnect  1            auto  auto 10/100/1000Ba seTX However, at 10:03 AM, it log the same error again

[lgijssel]

You are providing poor information and I think you are messing up devices.

The error is about gi4/0/43. That must be in a stack because of the interface number.

However, the image you are showing displays a single switch.

Hence, I do not think this is the switch that corresponds to the error message.

People are spending time here to help you, the least you can do is being polite and provide proper feedback.

Rating a post would not be a bad idea either.

regards,

Leo

[blin]

Yes, it is stack and we have total switches. I am not Cisco Engineer, but I am willing to provide the inforamtion you need. What do you need?

[lgijssel · Accepted solution]

No more info is required. It's all in this piece of your previous post:

Gi4/0/43                    err-disabled 1            auto  auto 10/100/1000B seTX BG3750_1-1

#show run int gi4/0/43 Building configuration...

Current configuration : 156 bytes !

interface GigabitEthernet4/0/43

switchport trunk encapsulation dot1q

switchport mode trunk

spanning-tree portfast

spanning-tree bpduguard enable

end

This clearly shows the port is in error-disabled state. This is normal when bpduguard is enabled on a port which is also there.

It will remain in err-disabled state, even after the cable is removed.

You need to manually reset it using a shut and then no shut command on the port to return it to operational state.

Could somebody have entered the wiring cabinet and plugged a cable in the switch? That is the most plausible explanation.

regards,

Leo

[blin]

I have removed “spanning-tree bpduguard enable” at 2:11 PM. The below is the result. I will monitor and will post back. One more question, we hired a Cisco Engineer to configure all switches for us and most ports are configured “spanning-tree bpduguard enable”. Should we remove all of them?

interface GigabitEthernet4/0/43

switchport trunk encapsulation dot1q

switchport mode trunk

spanning-tree portfast

end

BG3750_1-1#sh int gi4/0/43 status Port      Name              Status      Vlan      Duplex  Speed Type

Gi4/0/43                    notconnect  1            auto  auto 10/100/1000Ba seTX BG3750_1-1#

[blin]

Update. Now, another port Gi4/0/48 has the same error (see attached screenshot). The switch is located my next door and no one in the room today for sure. No device connecting.

BG3750_1-1#sh int gi4/0/48 status

Port      Name              Status      Vlan      Duplex  Speed Type

Gi4/0/48                    notconnect  1            auto  auto 10/100/1000BaseTX

[cadet alain · Accepted solution]

But this time the status shows it as notconnect which is normal if no other device is connected and as you have removed bpdu guard it wont be in errdisabled state anymore.

I think you should open a TAC case if you are really sure no one is linking a hub or switch to your ports but I've never used a switch stack so maybe this

type of problem is know on such an infrastructure.

Regards.

[lgijssel]

Alain is right: notconnect is not the same as errdisable.

This is normal behavior and the port should come up normally when a device is plugged into it.

A stack behaves exactly like a standalone switch. Frankly, I cannot see what should be the problem here.

regards,

Leo