CHAPTER Network protocols and network systems 2 INTRODUCTION The technical area of telecommunications and networking is a mature area of engineering that has experienced significant contributions for more than a century. The continuous evolution of cost-effective media, communication protocols, network designs, and network systems has led to dramatic changes in communications and networking. The effects have been particularly remarkable during the last few decades, when advances in fiber optics and high-speed transmission techniques in wire-based and wireless networks have brought significant amounts of bandwidth to users at the office, at home, or on the go, enabling a wide range of applications and services.