Modern IT (information technology) applications would not be possible if it were not for innovations in communication network technology. Indeed, major IT system vendors and consultancy firms, including Digital Equipment, were saying at the end of the 1980s: “The network is the system”. Over the past 20 years, IT systems have evolved from the development of centralized systems, through main frame systems, to distributed computing environments. Supporting network developments include client-server technology and Intranet/Internet technology. These developments have offered users even more flexibility and functionality but at a price-the networks systems supporting IT applications have become more and more complex.