Patent ID: 8537860

Claim:
A data center, comprising: a physical machine running a plurality of virtual machines including a source virtual machine and a destination virtual machine, the physical machine having a physical network interface in communication with the plurality of virtual machines and with a network, the source virtual machine issuing a data unit addressed to the destination virtual machine, the physical network interface transmitting a partial portion of the data unit over the network while a majority portion of the data unit remains stored in memory at the physical machine if the data unit is a unicast data unit, and transmitting the entire data unit over the network if the data unit is a multicast or broadcast data unit; and a network switch on the network, the network switch having a physical port receiving the partial portion of the data unit or the entire data unit transmitted by the physical network interface, the network switch returning the partial portion of the data unit or the entire data unit to the physical network interface through the same physical port, wherein the physical network interface identifies the data unit stored in the memory in response to the partial portion returned from the network switch and forwards the identified data unit to the destination virtual machine.