2960 Duplicate IP

Unanswered Question
Jul 22nd, 2008

Can someone please post a link or tip me on how to and which commands to troubles duplicate ip's on my 2960?

the error I get is: 40w5d: %IP-4-DUPADDR: Duplicate address 10.0.254.253 on Vlan254, sourced by 001e.49ee.0c00

I took a quick look and traced that MAC to the core, but I don't know what to do from there:

SPOT-CHI-6509E-01#sh mac- | i 0c00

* 600 001e.49ee.0c00 dynamic Yes 0 Po8

* 111 001e.49ee.0c00 dynamic Yes 0 Po8

* 110 001e.49ee.0c00 dynamic Yes 0 Po8

* 100 001e.49ee.0c00 dynamic Yes 0 Po8

* 253 001e.49ee.0c00 dynamic Yes 0 Po8

* 252 001e.49ee.0c00 dynamic Yes 5 Po8

* 254 001e.49ee.0c00 dynamic Yes 0 Po8

* 250 001e.49ee.0c00 dynamic Yes 0 Po8

* 500 001e.49ee.0c00 dynamic Yes 0 Po8

* 691 001e.49ee.0c00 dynamic Yes 0 Po8

* 690 001e.49ee.0c00 dynamic Yes 0 Po8

* 41 001e.49ee.0c00 dynamic Yes 0 Po8

* 40 001e.49ee.0c00 dynamic Yes 0 Po8

* 7 001e.49ee.0c00 dynamic Yes 0 Po8

* 4 001e.49ee.0c00 dynamic Yes 0 Po8

* 5 001e.49ee.0c00 dynamic Yes 0 Po8

* 2 001e.49ee.0c00 dynamic Yes 0 Po8

* 3 001e.49ee.0c00 dynamic Yes 0 Po8

* 10 001e.49ee.0c00 dynamic Yes 0 Po8

* 11 001e.49ee.0c00 dynamic Yes 0 Po8

* 9 001e.49ee.0c00 dynamic Yes 0 Po8

* 8 001e.49ee.0c00 dynamic Yes 0 Po8

* 12 001e.49ee.0c00 dynamic Yes 0 Po8

* 13 001e.49ee.0c00 dynamic Yes 0 Po8

* 14 001e.49ee.0c00 dynamic Yes 5 Po8

* 30 001e.49ee.0c00 dynamic Yes 0 Po8

* 20 001e.49ee.0c00 dynamic Yes 0 Po8

* 300 001e.49ee.0c00 dynamic Yes 0 Po8

Not real sure what this means, but it looks like it's registered on every VLAN that's used.

Thanks

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francisco_1 Tue, 07/22/2008 - 06:33

a device on your network is conflicting with your switch IP address 10.0.254.253 on Vlan254.

"* 254 001e.49ee.0c00 dynamic Yes 0 Po8".

this means that the device conflicting is connected to a another switch via port-channel 8 from this switch. do show cdp int (use one of the interface in the port-channel 8) to find out the switch you need to login to and use the command below to logcate the port the device is connected to.

switch# sh cdp neighbors int fa0/1

switch#sh mac address-table address

001e.49ee.0c00

vtra Tue, 07/22/2008 - 09:36

I'm going to try your solution once the market closes and the trading stops. I'll Let you know, thank you very much for the help.

h.parsons Tue, 07/22/2008 - 11:04

That MAC is registered to Cisco, maybe that will narrow it down some.

lgijssel Tue, 07/22/2008 - 11:30

The adress looks like a typical switch base adress. What is not so widely known is that Cisco uses the same mac adress for every vlan interface on the box which is why you are seeing the same mac on different vlans. This is normally not a problem because mac adresses only need to be unique on the subnet and they are not propagated beyond that.

You should be looking for a switch that has ip configured on all these vlans.

note: virtual mac's (hsrp) are unique within the network because they are calculated using the vlan id.

regards,

Leo

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