We are witnessing a growing interest in Networks on Chips (NoC) that is related to the evolution of integrated circuit technology and to the growing requirements in performance and portability of electronic systems. Current integrated circuits contain several processing cores, and even relatively simple systems, such as cellular telephones, behave as multiprocessors. Moreover, many electronic systems consist of heterogeneous components and they require efficient on-chip communication. In the last few years, multiprocessing platforms have been developed to address high performance computation, such as image rendering. Examples are Sony’s emotion engine [OKA] and IBM’s cell chip [PHAM] where on-chip communication efficiency is key to the overall system performance.