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Re: 3500XL - duplicate IP and Windows NT/2000 ser [7:73868] posted 08/12/2003
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Oops, I read the post as if the MACs were duplicated.

I have also come across a situtation where a faulty station (Wyse 
terminal actually) responded to all ARPs as if it owned the IP. I had an 
interesting conversation with Wyse support who remained convinced that 
it was impossible for their terminals to do that, since they weren't 
programmed that way. The fact that I had a packet capture of it 
happening didn't even phase them!

I ended up tracing down the Wyse terminal via its MAC (it wasn't 
changing ports as described in the original post) and replaced it.

Windows computers use ARPs to detect duplicate IPs. Perhaps something 
similar is happening? It could also be a Proxy ARP issue.

Zsombor Papp wrote:
> There are duplicate IP addresses, not duplicate MACs. And all the duplicate
> IP addresses come from the same MAC address, as if a single machine had
> suddenly all the IP addresses configured on the same interface. I don't see
> how this can be attributed to a L2 loop.
> 
> Firesox, what is this phantom MAC address?
> 
> Thanks,
> 
> Zsombor
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