In vSphere, a bound physical NIC can be configured to transmit and receive Jumbo Frames. What is the Maximum Transmission Unit (MTU) for Jumbo Frames in vSphere?
ESX Configuration Guide ESX vCenter Server, page 58.
Jumbo frames allow ESX to send larger frames out onto the physical network. The network must support jumbo frames end-to-end. Jumbo frames up to 9kB (9000 bytes) are supported.