Due to the network technology advances, an orderof- magnitude jump has been produced in the network bandwidth. This fact has reawake the interest in protocol offloading (particularly in protocols such as TCP, that require a lot of CPU resources to process the stack), since network communication is one key factor for the system performance. Nevertheless, there are controversial studies on protocol offloading benefits, and much research work on offloading, particulary on TCP offloading as it has been the main transport protocol for many years, and in fact, it is the most used protocol in the networks.

This paper describes a model to simulate by Simics the protocol offloading technique to keep low the communication overheads on the host CPU. The simulation platform provided by Simics can be used for a functional system simulation, including the application program, the operating system, the protocol stack and the device drivers, since networkoriented applications require a full-system simulation. As Simics does not provide a detailed network I/O model, in this paper we describe the way we have generated a model that allows the simulation of the offloading effects.