A guy asked me a question: he has IBM BladeCenter Chassis E with HS21 blade and ESXi 4.0. There are 2 Windows 2003 VMs.
Both VMs report about duplicate IP address on boot. Of course all was checked and there are no servers on network with these IP's.
This problem does not exist on HP blades.
What we found:
Windows sends gratuitous ARPs on the network when binding an IP to one of its nic in order to detect duplicate IPs.
We have reflection filters which prevent multicast/broadcast packets sent from a VM through a particular uplink to be received by the same VM.
But in your case these gratuitous ARPs come back through another uplink (because the other uplink is in the same broadcast domain because it has the same VLAN) and they then bypass our reflection filters.
Windows receives its own ARPs which makes it believe that somebody else uses this IP.
So, how can we solve this problem?
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VMware vExpert '2009
http://blog.vadmin.ru
