Detection of Duplicate address

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Nov 13th, 2007
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We are having some kind of weird problem of duplicate address message appearing on servers. We are having two 2950 switches connected to each other by trunk. Vlans are configured on each switch. Both switch configuration are identical. Each server ( IBM-AIX ) is having two ethernet cards and each card is connected to each swicth in the same VLAN. In all there are 3 VLAN's in each switch. Similar kind of setup is working fine at many of our locations. But here servers flash duplicate ip address message, very much surprising !!

Second thing we found out that if we check cdp neighbor , each switch learn other switch from each server as if second swicth is directly connected vis server.

Can we moniter on swicth what is the problem. ?

Please share similar experience or suggest a solution.

Thanx in advance


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Hieu Cao Tue, 11/13/2007 - 17:18
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do you have switchport security implemented in your switches?

have you verified that that ip address in use by your server is not being used anywhere else?

the error message that you see on your server should also indicate the mac address of the conflicting device. is that mac address familiar to you?

can you telnet to your switch and track down which port that mac is coming from.

can you also post a config.

good luck



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