This section discusses network adapters on legacy virtual machines.

If your virtual machine was created on ESX Server 3.0 or greater and runs a 32-bit guest operating system, the default adapter type is Flexible. The Flexible adapter functions as a Vlance adapter if the adapter’s driver is the stock driver the guest operating system. The Flexible adapter functions as a vmxnet adapter if the vmxnet driver has been installed on the virtual machine as part of the VMware Tools installation.

If your virtual machine runs a 64-bit guest operating system, the default adapter type is E1000. If you change a virtual machine from a 32-bit to a 64-bit guest operating system, or the reverse, you must remove the existing network adapter and replace it with a new one, or the virtual machine will not power on.

If you do a hardware upgrade on a legacy virtual machine, the adapter type for that upgraded machine is as follows:

If the adapter type was Vlance, the adapter type on the upgraded virtual machine is Flexible. That adapter functions as a Vlance adapter would function. If you want to obtain significantly better performance, you need only install the VMware Tools on the virtual machine as described in the previous step.

If the adapter type is vmxnet, the adapter type on the upgraded virtual machine is still vmxnet. However, you cannot change this adapter’s type to Vlance, as you would have been able to do on a legacy virtual machine.