Description
An Introduction to Information Networks
The learning goals for this chapter are as follows:
◾ Understand the structure of the worldwide information superhighway, commonly known as the Internet, as well as the various components that are inherent to its operation.
◾ Explore the numerous ways in which the Internet can be accessed through a variety of networks and transmission media
◾ Learn the composition of the network core that forms the Internet backbone and the organizations that support its continued development
◾ Learn the difference between packet switching and circuit switching, as well as the ramifications of each
◾ Understand the layers of the protocol stack that are used to support the interaction of computers connected to the Internet
◾ Learn the operations performed by the various layers of the protocol stack and the manner in which they affect the data, traveling in packets
◾ Obtain an overview of the role of security in the Internet
◾ Learn the manner in which the Internet has developed throughout its history
There are three primary goals for this book: (1) understand the many facets and ramifications of the Internet and the wide spectrum of applications that it affords, (2) obtain a thorough grasp of computer networks, the various structures and myriad ways in which they are applied, and finally (3) learn how to apply the latest advances in Internet security in order to protect the networks and the large variety of applications running on them. Every attempt will be made to present the material in an easily understandable fashion. As such, the book will contain a plethora of aids that support the rapid assimilation of the material so that the reader can apply it as quickly as possible.
The goals of this text will be accomplished through a systematic progression of material that supports a rapid learning process. The book will be divided into parts, each of which will consist of several chapters. The different parts and the subjects that will be addressed in each are listed in Table I.1.
In this initial chapter we begin to lay the groundwork for our analysis of the concepts that form the foundation of our study of the Internet and the plethora of ways in which they can be employed. We will provide an overview of the Internet architecture and then zoom in on the access networks with which Internet users are typically familiar, together with the backbone that supports them.
The Internet contains a constant flow of information and this information is contained in packets. The manner in which these packets are switched is fundamental to the operation of the Internet. The Internet protocols, software, hardware, commands and similar functions that support packet switching are modularized in what are called protocol stacks and each layer of the stack performs a specific and vital function. These functions will be discussed in detail as we progress through the book. As will be indicated later, packet switching is a best effort delivery and suffers from the fact that delay jitter is inherent in its operation. In contrast, circuit switching does not have this drawback and therefore is best for voice and video. Packet switching requires the use of protocols to reserve bandwidth and resources in order to mimic circuit switching operations.
Finally, a basic overview of various types of malware will be presented together with the various security systems, containing such things as firewalls, intrusion detection systems and the like. Network security is a fundamental issue and plays a vital role in the construction and operation of viable computer networks.
Given this conceptual view of the material to follow, let us now begin our presentation by first providing a global picture of the Internet.