%STANDBY-3-DUPADDR error log

[Ravan Nagalingam]

Hi,

I got the Following Error log in my Core switch, need help to figure out what happend?

May 13 16:25:38 MAL: %STANDBY-3-DUPADDR: Duplicate address 129.253.144.250 on Vlan20, sourced by 0000.0c07.ac14

May 13 16:25:51 MAL: %DUAL-5-NBRCHANGE: IPX-EIGRP 1: Neighbor 81FD9000.0014.f1bc.0c00 (Vlan20) is down: Interface Goodbye received

May 13 16:25:51 MAL: %DUAL-5-NBRCHANGE: IPX-EIGRP 1: Neighbor 81FD9000.0014.f1bc.0c00 (Vlan20) is up: new adjacency

May 13 16:25:51 MAL: %DUAL-5-NBRCHANGE: IPX-EIGRP 1: Neighbor 81FD9000.0014.f1bc.0c00 (Vlan20) is down: Interface Goodbye received

May 13 16:25:51 MAL: %DUAL-5-NBRCHANGE: IPX-EIGRP 1: Neighbor 81FD9000.0014.f1bc.0c00 (Vlan20) is up: new adjacency

May 13 16:25:51 MAL: %DUAL-5-NBRCHANGE: IPX-EIGRP 1: Neighbor 81FD9000.0014.f1bc.0c00 (Vlan20) is down: Interface Goodbye received

May 13 16:25:51 MAL: %DUAL-5-NBRCHANGE: IPX-EIGRP 1: Neighbor 81FD9000.0014.f1bc.0c00 (Vlan20) is up: new adjacency

May 13 16:25:51 MAL: %DUAL-5-NBRCHANGE: IPX-EIGRP 1: Neighbor 81FD9000.0014.f1bc.0c00 (Vlan20) is down: Interface Goodbye received

May 13 16:25:51 MAL: %DUAL-5-NBRCHANGE: IPX-EIGRP 1: Neighbor 81FD9000.0014.f1bc.0c00 (Vlan20) is up: new adjacency

From my understanding is the following host with the Mac-add 0000.0c07.ac14, has stolen the Ip address 129.253.144.250.

What i don't get is how can a a standby IP, source the a physical ip address of the same vlan.

interface Vlan20

description CIM VLAN

ip address 129.253.144.250 255.255.248.0

ip access-group Exfilter in

ipx input-sap-filter 1000

ipx network 81FD9000

ipx network 81FD9002 encapsulation SAP secondary

ipx network 81FD9003 encapsulation SNAP secondary

standby 20 ip 129.253.144.254

standby 20 timers 1 3

standby 20 priority 110

end

Can anyone help figure out what happend over here.

[Gabriel Hill · Accepted solution]

Hello Ravan,

Here is a good place to start:

http://www.cisco.com/en/US/tech/tk648/tk362/technologies_tech_note09186a0080094afd.shtml#t20

The first thing I would check is your spanning-tree environment on vlan 20.

- Gabriel

[Ravan Nagalingam]

thanks gabriel, will look into it

[InayathUlla Sharieff]

Hi Ravan,

Duplicate address issue is often due to loop in the network. . The HSRP hellos are getting looped and coming back to the same switch.  enable mac flap notification.

conf t

mac-add notifi mac-move

in case the mac is flapping between the port-channel and one of the links in the port-channel then the port-channel is not bundled properly( i dont think this is the case as it is only vlan 20 which is having the problem, had it been the PC you would see some more vlans flapping). My guess is you will see the mac address flapping between the PC and some other access port in vlan 20. Neverthless idea is to track down the loop by tracking the mac address starting from the port where it is NOT supposed to learn. E.g if you see the mac address flappign between Port X & Port Y and Port X is the one where it is supposed to learn the mac address then jump on to the device connected to Port Y. if the device is a switch enable mac-move notification on that device as well, follow the same troubleshooting step as described above till you reach an access port or a end device/hub. Shut down the access port from where it is not supposed to learn the mac to break the loop or remove the  end device causing the loop.

HTH

Regards

Inayath

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