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This textbook presents a detailed introduction to the essentials of networking and communications technologies. Revised and updated, this new edition retains the step-by-step approach of the original, organised to help those without a strong knowledge of the subject matter. Features: provides chapter-ending summaries and review questions, an Appendix on TCP/IP packet formats and an expanded Glossary; supplies supplementary material at the associated Springer website, including teaching slides, solutions to the end-of-chapter questions and supplementary exercises with solutions; presents a greater emphasis on mobile computing and network security, and extended coverage of IPv6 (NEW); discusses networking models and standards, local area and wide area networks, network protocols, TCP/IP-based networks, network management and wireless communications; examines grid and cloud computing, microblogging, mobile ad hoc networks, near-field communication, Power over Ethernet and the Ground Positioning System (NEW).



1. Introduction

This short chapter starts by considering how we can define what a network is. Next, there is a short discussion of different types of networks. This is followed by an account of the reasons why networks are used. Then, there is a discussion of communication between computers. Several basic terms used when discussing computer communication are introduced.

John Cowley

2. Communications Technologies

In this chapter, we look at some of the technologies that are used for computer communications. The chapter starts with an explanation of the differences between serial and parallel data transfer, asynchronous and synchronous communications and duplex, half-duplex and full-duplex communications. There are explanations of the distinctions between data rate, bandwidth and throughput. Next come discussions of modulation and encoding, error control methods, switching and multiplexing. The topologies used in networking are described. Finally, we explore network transmission media.

John Cowley

3. Networking Models and Standards

In this chapter, we look at layered models, which are standard ways of organising networks. The chapter starts with an explanation of network layering and its advantages. Next, there is a description of one of the most important networking models, the open systems interconnection (OSI) 7-layer model. An explanation of the principles of data encapsulation follows. Another important networking model, TCP/IP, is then explained and compared with the 7-layer model. Finally, we look at several important networking standards bodies.

John Cowley

4. Local Area Networks

In this chapter, we look at various aspects of LANs. The chapter starts with an account of some of the factors that we need to consider when planning a LAN. We look at the choices between a peer-to-peer and client–server LAN and between a wired and wireless network. There are descriptions of various components and devices for both wired LANs and wireless LANs (WLANs). Brief descriptions of several wired LAN technologies come next, but the chapter concentrates on Ethernet, which is the commonest of those technologies by far. Finally, we consider storage area networks and grid computing.

John Cowley

5. Wide Area Networks

Wide area networks (WANs) made a brief appearance in Sect. 1.2. We now look at WANs in a little more detail. The chapter starts with a consideration of the general characteristics of WANs. After a brief mention of the use of the public switched telephone network (PSTN) for computer networks, there is a description of the packet-switching technology frame relay. Integrated Services Digital Network (ISDN), an all-digital, circuit-switched service, comes next. Then, there is a description of digital leased lines. We follow this with coverage of digital subscriber line and cable modem, which offer alternative ‘always-on’ broadband services. Then, we look at some ways of accessing LANs remotely. Next is a section on routers, which are devices that are used to connect networks together. We cover the use in WANs of two technologies that were described in

Chap. 4

, ATM and Ethernet. Finally, we consider cloud computing, in which information technology services are offered over the Internet.

John Cowley

6. Network Protocols

This chapter deals with network protocols of various kinds, especially transmission control protocol/Internet protocol (TCP/IP) and related protocols. It concentrates heavily on IP and TCP themselves. We give attention to both IP version 4 and IP version 6. A section on Internet control message protocol (ICMP), which is used in TCP/IP networks to send error messages and informational messages of various kinds, precedes the material on TCP. High-level data link control (HDLC), a layer-2 protocol that is used in WANs, features next. There is brief coverage of multiprotocol label switching, which permits highly efficient routing. Finally, there are descriptions of two different classes of routing protocols, which allow routers to inform each other about networks that they know about without human intervention.

John Cowley

7. Internet Application-Layer Protocols

In the previous chapter, we saw how IP packets carry TCP segments or UDP datagrams across networks. Now it is time to look at what happens in the top layer of a TCP/IP-based network, the application layer. This chapter starts with an explanation of client–server technology, which underlies most Internet activities. We examine the following applications in turn: the domain name system (DNS), the World Wide Web, remote access, file transfer, E-mail, the delivery of streamed content over the Internet and voice over IP (VoIP). We discuss the main protocols for each of these applications. The chapter ends with brief descriptions of peer-to-peer (P2P) file sharing, instant messaging (IM) and microblogging.

Note that all the applications described below depend on TCP/IP and the underlying network to deliver the data. If necessary, please refer back to Chap. 3 or to Sect. 7.4.1 for a reminder of the encapsulation process.

John Cowley

8. Network Security

Network security is one of the tasks of network management, other aspects of which we deal with in the next chapter. However, network security is such an important issue that this chapter is devoted to it. The chapter starts with an explanation of several important security concepts and gives some security techniques related to these concepts. We examine the following aspects of network security in turn: virtual private networks (VPNs); firewalls; intrusion detection, intrusion prevention and unified threat management systems; various kinds of attacks that may be made on networks; viruses, worms and Trojan horses; rootkits; spam e-mail; spyware; phishing; social engineering; dynamic Web links; and physical security. Wireless networks receive detailed coverage in Chap. 10, but there is a section on wireless LAN security in this chapter. Finally, we consider the security of mobile devices.

John Cowley

9. Network Management

This chapter begins with a description of the network management functional areas of the ISO network management model, which cover configuration management, fault management, performance management, accounting management and security management. Next comes a description of some hardware and software tools that are used for network management. We then look at some ways of troubleshooting networks. We investigate the important simple network management protocol (SNMP), a TCP/IP application-layer protocol that makes it easy for management information to be exchanged between network devices. We also take a look at the equally important variant of SNMP, remote monitor (RMON). In the next section, the value of good network documentation is stressed. The chapter ends with a short section on LAN server administration.

As networks become more and more complex, they can become more and more difficult to maintain. The users of a network tend to rely on it heavily and will suffer if it is not running efficiently or if certain applications are unavailable when needed. So the network manager must manage the network proactively, using all the management facilities at his or her disposal.

John Cowley

10. Wireless Networks

Wireless networks have become more and more popular in business and industrial environments, in the home and in hotspots in public places such as airports and hotels. We can classify wireless networks in a variety of ways. In this chapter, we classify them as follows: personal area networks (PANs), home area networks (HANs), wireless LANs (WLANs), cellular radio networks (for mobile phones) and wireless technologies for replacing the wired analogue local loop. We start with a mention of some technical aspects of transmission. The chapter finishes with short discussions of mobile ad hoc networks, radio frequency identification (RFID), near field communication and the global positioning system.

Certain aspects of WLANs were covered in previous chapters, and the reader is encouraged to refer back to these. Infrared and microwave transmission (including satellites) were mentioned in Sect. 2.10.3. The WLAN access point and radio (the wireless NIC) were described in Sect. 4.1.3. The particular security problems posed by WLANs were covered in Sect. 8.16.

John Cowley


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