BPDU Guard Error Disabled Issue Cisco IP Phone 7940

[Hamidsattarrana]

Hi!

Hope you guys are well.

We have access layer switches 2950 & 2960. Switchport is configured with Multi Vlan Access Port. Vlan 300 for Data & 400 for Voice. 

When IP phones is powered on and Ethernet cable is plugged, it works okay. 

Issue is when Ethernet cable is plugged & IP phones is powered off, it starts sending BPDU or MAC Flooding even it is powered off and goes to error disable state as. Configurations & logs are below of the switchport.  

My question: Why the IP Phone 7940/7960 went to error disable state even they are powered off? Is there anything wrong in my switchport configurations?

Access Switchport configurations is below:

interface FastEthernet0/30
description 405-A2
switchport access vlan 300
switchport mode access
switchport voice vlan 400
switchport port-security
switchport port-security maximum 5
switchport port-security aging time 5
switchport port-security aging type inactivity
logging event spanning-tree status
logging event trunk-status
no keepalive
storm-control broadcast level 20.00 10.00
storm-control multicast level 20.00 10.00
storm-control unicast level 20.00 10.00
storm-control action trap

storm-control action shutdown
spanning-tree portfast
spanning-tree bpduguard enable
ip dhcp snooping limit rate 100
end

Interface logs Output when Ethernet cable is plugged and IP Phone's charger is unplugged:

015091: Nov 5 05:40:41.094 UTC: %SPANTREE-6-PORT_STATE: Port Fa0/30 instance 300 moving from forwarding to disabled
015092: Nov 5 05:40:41.098 UTC: %SPANTREE-6-PORT_STATE: Port Fa0/30 instance 400 moving from forwarding to disabled
015093: Nov 5 05:40:42.090 UTC: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/30, changed state to down
015094: Nov 5 05:40:42.942 UTC: %SPANTREE-6-PORT_STATE: Port Fa0/30 instance 300 moving from disabled to blocking
015095: Nov 5 05:40:42.942 UTC: %SPANTREE-6-PORT_STATE: Port Fa0/30 instance 300 moving from blocking to forwarding
015096: Nov 5 05:40:42.946 UTC: %SPANTREE-6-PORT_STATE: Port Fa0/30 instance 400 moving from disabled to blocking
015097: Nov 5 05:40:42.946 UTC: %SPANTREE-6-PORT_STATE: Port Fa0/30 instance 400 moving from blocking to forwarding
015098: Nov 5 05:40:44.102 UTC: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/30, changed state to up
015099: Nov 5 05:40:45.846 UTC: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port FastEthernet0/30 with BPDU Guard enabled. Disabling port.
015100: Nov 5 05:40:45.850 UTC: %PM-4-ERR_DISABLE: bpduguard error detected on Fa0/30, putting Fa0/30 in err-disable state
015101: Nov 5 05:40:45.850 UTC: %SPANTREE-6-PORT_STATE: Port Fa0/30 instance 300 moving from forwarding to disabled
015102: Nov 5 05:40:45.854 UTC: %SPANTREE-6-PORT_STATE: Port Fa0/30 instance 400 moving from forwarding to disabled
015103: Nov 5 05:40:46.850 UTC: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/30, changed state to down
015104: Nov 5 05:40:47.858 UTC: %LINK-3-UPDOWN: Interface FastEthernet0/30, changed state to down

And the port goes into error disabled state.

Thanks & Regards!

Hamid...

[Mark Elsen]

          - Does it for instance have a lan port in use, triggering this problem by a foreign device attached ?

 M.

[paul driver]

Hello
So the switchport is receiving bpdu's and err-disabling as per logs that’s the problem
You say the ethernet cable is directly connected to the phone and when the phone is powered off via a POE injector and not POE from the switchport err-disable occurs?

Do you have any other device in between the phone and the switchport, why is it your using a POE injector?

[Hamidsattarrana]

No. I don't have another devices between the switch & the IP Phone. It's connected directly to the switch. We don't have POE switches. Therefore we are using IP Phone adapter to power it up.

I know that the switch-port is receiving BPDU that is causing it to go into error disabled state.

The question here why the phone is sending out BPDU even it's not plugged with the Power Injector/Adapter?

[Georg Pauwen · Accepted solution]

Hello,

check if you might be hitting the bug below. The Cisco IP Phone does not use BPDUs to form the trunk, it just uses CDP.

2950 ports connected to ip phone goes to err-dis when phones are powered
CSCsh31752
Description

Symptom:
2950 ports connected to ip phone goes to err-dis when phones are powered

Conditions:
Issue has been observed on WS-C2950T-48-SI only, when ip phone (7940 and 7960) are powered port goes into err-disable due to bpdu-guard. Also customer is reporting that after shut/no shut port is not able to reach the call manager.This behavior has been observed on switches that were upgraded to 12.1(22)EA6, reverting back to 12.1(22)EA3 solved the issue.

Workaround:
reverting back to 12.1(22)EA3

[paul driver]

@Georg Pauwen  +5  Its the correct switch and phone version -Looks like thats a possible root cause

[Hamidsattarrana]

Thanks for helping. I have tested the Cisco IP Phone with same configuration on Cisco 3750-G switch and there is no BPDU error like I have on Cisco 2950 (Model No.Model number: WS-C2950SX-48-SI) with IOS installed c2950-i6q4l2-mz.121-22.EA4a.bin.

Thanks Georg