BPDU Guard, err-disabled error

[rinish-mr]

Hello ,

Computer is connected to a Cisco IP Phone. Last week, the port gets err-disabled 4-5 times. Switch logs shows the following.

Oct 13 05:22:58.620 CCT: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port Fa1/ 0/19 with BPDU Guard enabled. Disabling port. (CN-WUHRC-RCAS04-1)
Oct 13 11:21:08.160 CCT: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port Fa1/ 0/19 with BPDU Guard enabled. Disabling port. (CN-WUHRC-RCAS04-1)
Oct 13 11:59:28.463 CCT: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port Fa1/ 0/19 with BPDU Guard enabled. Disabling port. (CN-WUHRC-RCAS04-1)
Oct 13 12:29:26.317 CCT: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port Fa1/ 0/19 with BPDU Guard enabled. Disabling port. (CN-WUHRC-RCAS04-1)
Oct 13 13:07:19.926 CCT: %SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port Fa1/ 0/19 with BPDU Guard enabled. Disabling port. (CN-WUHRC-RCAS04-1)

And only IP phone and PC is connected to this port . And later i tried with a new patch cable and issue got resolved.

Can anybody comment on this ? How physical cable and BPDU are related ?

Following are the interface configuration..

sh run inte fa 1/0/19
Building configuration...

Current configuration : 343 bytes
!
interface FastEthernet1/0/19
switchport access vlan 222
switchport mode access
switchport voice vlan 502
srr-queue bandwidth share 10 10 60 20
priority-queue out
mls qos trust device cisco-phone
mls qos trust cos
auto qos voip cisco-phone
spanning-tree portfast
spanning-tree bpduguard enable
service-policy input QOS_MARK
end

c3750-ipservicesk9-mz.122-50.SE4.bin..

[Georg Pauwen]

As far as I know, bad cables can cause packet corruption, which in turn can cause STP related problems.

Although that is a remote possibility, the error counters in the output of the 'show interfaces' command should include runts, giants, no buffer, CRC, frame, overrun, and ignored counts.

Do you see any of those on the interfaces that are disabled ?

[rinish-mr]

No, I did not see..

[Mark Malone]

There should be something in your show interfaces if its a faulty cable that caused it ? a bad NIC  can cause it as wel when just pc and phone , maybe NIC had an issue too and pulling the cable may have fixed it

Packet Corruption

Packet corruption can also lead to the same kind of failure. If a link has a high rate of physical errors, you can lose a certain number of consecutive BPDUs. This loss can lead a blocking port to transition to forwarding state. You do not see this case very often because STP default parameters are very conservative. The blocking port needs to miss BPDUs for 50 seconds before the transition to forwarding. The successful transmission of a single BPDU breaks the loop. This case commonly occurs with the careless adjustment of STP parameters. An example of an adjustment is max-age reduction.

Duplex mismatch, bad cables, or incorrect cable length can cause packet corruption