How do i found what cisco equipment has a mac address - duplicate IP

[tony.klapisch1]

We are having constant issues with a duplicate IP address that we are unable to locate

We have the SAME mac address causing issues in a wireless scope on a DHCP server (MS 2K8R2) against multiple devices. Can someone please advise how we go about asking for or finding the real equipment type /ID based upon a mac address in the 

BC-F1-F2-XX-XX-XX range

We know the mac address is a Cisco owned one, but we need to try and determine what the offending piece of equipment is! by the time we are advised of the issue occuring again, there are no records in any of the arp caches to find

If we can find the type of equipment then at least we wil lknow what we are  looking for, voip phone/ switch/ router / firewall etc

Any and all help appreciated

A very frustrated Admin

Tony K

[John Blakley]

Do you know how to track down a standard host via the mac address table, etc? It would be the same thing. To sum it up, get on your main device and look for the mac in the table. Find out what port it goes out of and then get on the switch that connects to that port. Repeat the process until you've exhausted every switch in the environment. 

HTH,

John

[Suresh Vinayagam Subramanian]

Hi Tony ,

This could be either there is loop in your network or device connected with dual home and both in forward state. 

you can use command " show mac address <that mac-add> " to find how we learned that mac and trace further till we reach the end device .

Example :

BC-F1-F2-XX-XX-XX flapps between interface gi1/0/1 and po1

this mac BC-F1-F2-XX-XX-XX mac is learned thr' gi1/0/1 and po1. so if you do " show mac add BC-F1-F2-XX-XX-XX" then it will show one time learned via gi1/0/1 and other time po1.

Do "show cdp neighbor gi1/0/1 and po1 " to identify what is connected and login to that switch and do trace the mac by " show mac add <mac>" do the same till you reach the end device .

HTH
Regards,
VS.Suresh.
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