Taking server virtualization down from the clouds to real life experience ... In my previous post I warned that VMware has removed some drivers for officially unsupported NICs (Realtek and Marvell) from ESXi 5.5 (compared to ESXi 5.1 and 5.0 that still included them). These drivers still work with ESXi 5.5, and if you upgrade an ESXi 5.1 host to 5.5 then you can just keep and continue using them.