1. A method comprising: building a set of descriptors that describe the operations to be performed by a Protocol DMA Engine; wherein a host processor builds the set of descriptors in lieu of performing the operations described by the descriptors; providing the set of descriptors to the Protocol DMA Engine; processing a protocol layer input data unit by means of the Protocol DMA Engine whereby the Protocol DMA Engine executes the operations described in the set of descriptors to produce a protocol layer output data unit; and providing the protocol layer output data unit to a next layer of a network protocol stack.