IP for 3G - (P3)

An Introduction to IP NetworksThe Internet is believed by many to have initiated a revolution that will be as far reaching as the industrial revolution of the 18th and 19th centuries. However, as the collapse of many ‘dot.com’ companies has proven, it is not easy to predict what impact the Internet will have on the future. In part, these problems can be seen to be those normally associated with such a major revolution.
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IP for 3G - (P3) IP for 3G: Networking Technologies for Mobile Communications Authored by Dave Wisely, Phil Eardley, Louise Burness Copyright q 2002 John Wiley & Sons, Ltd ISBNs: 0-471-48697-3 (Hardback); 0-470-84779-4 (Electronic) 3 An Introduction to IP Networks3.1 Introduction The Internet is believed by many to have initiated a revolution that will be as far reaching as the industrial revolution of the 18th and 19th centuries. However, as the collapse of many ‘dot.com’ companies has proven, it is not easy to predict what impact the Internet will have on the future. In part, these problems can be seen to be those normally associated with such a major revolution. Or perhaps the dot.com collapses were simply triggered by the move of the Internet from primarily a government funded university research network to commercial enterprise and the associated realisation that the Inter- net is not ‘free’. Thus, whilst the Internet is widely acknowledged to have significantly changed computing, multimedia, and telecommunications, it is not clear how these technologies will evolve and merge in the future. It is not clear how companies will be able to charge to cover the costs of providing Internet connectivity, or for the services provided over the Internet. What is clear is that the Internet has already changed many sociological, cultural, and business models, and the rate of change is still increasing. Despite all this uncertainty, the Internet has been widely accepted by users and has inspired programmers to develop a wide range of innovative appli- cations. It provides a communications mechanism that can operate over different access technologies, enabling the underlying technology to be upgraded without impacting negatively on users and their applications. The ‘Inter-Networking’ functionality that it provides overcomes many of the technical problems of traditional telecommunications, which related to inter-working different network technologies. By distinguishing between the network and the services that may be provided over the network, and by providing one network infrastructure for all applications, and so removing the inter-working issues, the Internet has reduced many of the complexities, and hence the cost, of traditional telecommunications systems. The Internet has an open standardisation process that enables its rapid evolution to meet 72 AN INTRODUCTION TO IP NETWORKS user needs. The challenge for network operators is therefore to continue to ensure that these benefits reach the user, whilst improving the network. This chapter summarises the key elements and ideas of IP networking, focusing on the current state of the Internet. As such, the Internet cannot support real-time, wireless, and mobile applications. However, the Internet is continually evolving, and Chapters 4–6 detail some of the protocols currently being developed in order to support such applications. This chap- ter begins with a brief history of IP networks, as understanding the history leads to an understanding of why things are the way they are. It then looks at the IP standardisation process, which is rather different from the 3G process. A person, new to the IP world, who attempted to understand the IP and associated protocols, and monitor the development of new protocols, would probably find it useful to have an understanding of the underlying philosophy and design principles usually adhered to by those working on Internet development. The section on IP design principles also discusses the important concept of layering, which is a useful technique for structuring a complex problem – such as communications. These design principles are considered as to whether they are actually relevant for future wireless systems, and then each of the Internet layers is examined in more depth to give the reader an understanding of how, in practice, the Internet works. The penultimate section is devoted to indicating some of the mechanisms that are available to provide security on the Internet. Finally, a disclaimer to this chapter: the Internet is large, complex, and continually changing. The material presented here is simply our current understanding of the topic, focusing on that which is relevant to understand- ing the rest of this book. To discuss the Internet fully would require a large book all to itself – several good books are listed in the reference list.3.2 A Brief History of IP IP networks trace their history back to work done at the US Department of Defense (DoD) in the 1960s, which attempted to create a network that was robust under wartime conditions. This robustness criterion led to the devel- opment of connectionless packet switched networks, radically different from the familiar phone networks that are connection-oriented, circuit- switched networks. In 1969, the US Advanced Research Projects Agency Network – ARPANET – was used to connect four universities in America. In 1973, this network became in ...