Hi,
Do you have any other virtual machine connected in this same vswitch working without problem ?
I found this note : http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1001805
- Windows Server 2012 is supported with VMXNET 3 on ESXi 5.0 Update 1 or higher.