%STANDBY-3-DUPADDR Error on 6500 Switches

[jennyjohn]

On both my core switches, I am getting the error

On Core 1:

%STANDBY-3-DUPADDR: Duplicate address 10.87.21.252 on Vlan321, sourced by 0000.0d07.ac01

%STANDBY-3-DUPADDR: Duplicate address 10.87.121.252 on Vlan421, sourced by 0000.0d07.ac01

On Core 2:

%STANDBY-3-DUPADDR: Duplicate address 10.87.21.253 on Vlan321, sourced by 001b.8d12.7000

%STANDBY-3-DUPADDR: Duplicate address 10.87.121.253 on Vlan421, sourced by 001b.8d12.7000

I have more than 25 vlans on my Core switches but its showing error for only vlans 321 & 421. Both vlans of a site which is not directly connected to the core switch.

The HSRP configurations are correct and there does not seem to be any spanning tree loops in these vlans.

how can I fix this?

Thanks in advance.

[Leo Laohoo · Accepted solution]

0000.0d07.ac01 MAC address is a Fibronics Ltd. and 001b.8d12.7000 Electronic Computer Systems, Inc.  Does this make any sense to you?

[jennyjohn]

Hi leo, I had changed the mac addresses, so checking the vendor ID will show wrong vendor.

Just know this, the mac address that is appearing in the error message is the mac address of the router itself.

[Leo Laohoo]

Ok.  Thanks for the clarifications.  You'll need to find out what machine is statically configured with your standby IP address.

[jennyjohn]

We found out that somebody had connected a rogue switch to an access port with data vlan 421 & voice vlan 321. the following error was found in the logs.

%SPANTREE-2-BLOCK_BPDUGUARD: Received BPDU on port Gi2/6 with BPDU Guard enabled. Disabling port.
%PM-4-ERR_DISABLE: bpduguard error detected on Gi2/6, putting Gi2/6 in err-disable state
%PM-4-ERR_RECOVER: Attempting to recover from bpduguard err-disable state on Gi2/6

The bpduguard moved the port to err-disable and the errdisable recovery cause bpduguard command was recovering from the err-disable state after 300 seconds.

After shutting down the port the problem seems to have been fixed.

Thanks

[greensubmarine2009]

when i config the switch,after i finished the "portfast",i always config the "bpdu guard".

[Leo Laohoo]

There's a reason why I don't use "errdisable recovery cause bpduguard" with "spanning-tree bpduguard enable".   If the error disable recovery wasn't in the config you wouldn't have this issue.

[greensubmarine2009]

%STANDBY-3-DUPADDR: Duplicate address 10.87.21.252 on Vlan321, sourced by 0000.0d07.ac01

this log means there is a switch broadcast the hsrp's multicast flow into layer 2 broadcast,so the router seems its own mac address .

I met a trouble before:

a catalyst 6506 switch went to a hardware crash, and it broadcast whatever it received. it caused huge flow and hsrp 's switch.and the log server was full of "%STANDBY-3-DUPADDR: Duplicate address 10.87.21.252 on Vlan321, sourced by 0000.0d07.ac01".

[vvasisth]

looks like theere is a loop in the network you

need to follow the error message and check where the loop is being formed in the network then only we can start troubleshooting the issue.

regards,

Varun