dck aw 2/27/06 1:14 PM Page 1 Michael Duck and Richard Read D Michael Duck and Richard Read a t a C second edition o Data Communications m m and Computer Networks second edition u n for Computer Scientists and Engineers ic Data Communications a t i o n and Computer Networks s Afo cburosiandg ionntr othdeu cfutonrdya tmexetn wtarli tatesnp efcotrs coofm dpautat ecro smcimenutnisictsa taionnds e anngdin ceoemrsp,uter fo a networks. This second edition has been thoroughly revised to cover current r Cn networking issues and technologies. Specific updates include those on od for Computer Scientists and Engineers m networks and their management, transmission technologies, security and pC encryption. uo t em r This text is appropriate for modular courses in data communications as well S as computer science. It is also a useful source for professionals in related cp disciplines. ieu nt te i Key features of this edition sr t s • Unique and accessible overview of networking aN • Includes modern networking issues – management, security and encryption nde • Enhanced treatment of core network technologies including ATM and Etw n SDH/SONET g io n • New chapter on TCP/IP er ek • Focuses on the engineering aspects of data communications rs s • Covers international standards, with emphasis on those for Europe and North America • Numerous worked examples designed to improve the understanding of key principles Michael Duckis a professional engineer at Nortel Networks, EMEA. Richard Readis a Senior Lecturer in Computer Communications at Middlesex University and a freelance consultant. s D ec u o c n k d e a d n ition d R e a d www.pearsoneduc.com DCAA01 2/27/06 11:17 AM Page i Data Communications and Computer Networks for Computer Scientists and Engineers Second Edition DCAA01 2/27/06 11:17 AM Page ii We work with leading authors to develop the strongest educational materials in engineering, bringing cutting-edge thinking and best learning practice to a global market. Under a range of well-known imprints, including Prentice Hall, we craft high-quality print and electronic publications which help readers to understand and apply their content, whether studying or at work. To find out more about the complete range of our publishing, please visit us on the World Wide Web at: www.pearsoned.co.uk DCAA01 2/27/06 11:17 AM Page iii Data Communications and Computer Networks for Computer Scientists and Engineers Second Edition Michael Duck and Richard Read DCAA01 2/27/06 11:17 AM Page iv Pearson Education Limited Edinburgh Gate Harlow Essex CM20 2JE England and Associated Companies throughout the world Visit us on the World Wide Web at: www.pearsoned.co.uk First published 1996 Second edition 2003 ©Pearson Education Limited 1996, 2003 The rights of Michael Duck and Richard Read to be identified as authors of this work have been asserted by them in accordance with the Copyright, Designs and Patents Act 1988. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without either the prior written permission of the publisher or a licence permitting restricted copying in the United Kingdom issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London W1T 4LP. Many of the designations used by manufacturers and sellers to distinguish their products are claimed as trademarks. Pearson Education Limited has made every attempt to supply trademark information about manufacturers and their products mentioned in this book. A list of trademark designations and their owners appears below. Trademark notice The following designations are trademarks or registered trademarks of the organizations whose names follow in brackets: Cisco Systems (Cisco Systems, Inc.); Nortel Networks, Passport and Preside (Nortel Networks). ISBN-13: 978-0-13-093047-7 ISBN-10: 0-13-093047-4 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library Library of Congress Cataloging-in-Publication Data Duck, Michael. Data communications and computer networks : for computer scientists and engineers / Michael Duck and Richard Read.––2nd ed. p. cm. Includes bibliographical references and index. ISBN 0-13-093047-4 1. Computer networks. 2. OSI (Computer network standard) 3.Data transmission systems I. Read, Richard (Richard J.) II. Title. TK5105.5.D89 2003 004.6––dc21 2003043357 10 9 8 7 6 5 4 3 2 10 09 08 07 06 Typeset in 10/12pt Times by 35 Printed and bound in Great Britain by Henry Ling Ltd, at the Dorset Press, Dorchester, Dorset DCAA01 2/27/06 11:17 AM Page v To Marlon DCAA01 2/27/06 11:17 AM Page vi DCAA01 2/27/06 11:17 AM Page vii Contents Preface xi Acknowledgements xix 1 Introduction 1 1.1 The development of data communications 2 1.2 Types and sources of data 4 1.3 Communications models 6 1.4 Standards 7 1.5 Open Systems Interconnection 9 1.6 OSI Reference Model 13 1.7 Institute of Electrical and Electronic Engineers 802 standards 15 1.8 OSI Reference Model and other standards 16 Exercises 18 2 Data communications 19 2.1 Data transmission techniques 19 2.2 Network topology 29 2.3 Transmission media and characteristics 32 2.4 Baseband signalling 37 Exercises 48 3 Information theory 50 3.1 Information source 51 3.2 Information measure 52 3.3 Entropy 55 3.4 Source codes 57 3.5 Data compression 63 Exercises 82 vii DCAA01 2/27/06 11:17 AM Page viii viii Contents 4 Error control 83 4.1 Transmission impairments 83 4.2 Forward error control 85 4.3 Linear block codes 85 4.4 Convolutional codes 100 4.5 Feedback error control 106 Exercises 108 5 Data link control 110 5.1 Link throughput 110 5.2 Flow control 116 5.3 Link management 121 5.4 High-level Data Link Control (HDLC) protocol 122 5.5 Point-to-Point Protocol 129 Exercises 130 6 Modems 132 6.1 Modulation 133 6.2 Effect of noise upon digitally modulated signals 146 6.3 Equalizers 148 6.4 Channel capacity 149 6.5 Generalized modem 150 6.6 ITU-T V standards 151 6.7 Other types of modem 157 Exercises 159 7 Access networks 161 7.1 Integrated Services Digital Network 161 7.2 Broadband ISDN 170 7.3 xDSL 175 Exercises 181 8 Transport networks 182 8.1 Time division multiplexing 183 8.2 Pulse code modulation 185 8.3 Plesiochronous Digital Hierarchy 186 8.4 Synchronous Digital Hierarchy 188 Exercises 198 9 Introduction to local area networks 199 9.1 Medium Access Control 200 9.2 LAN performance 206 Exercises 215 10 LAN standards 217 10.1 IEEE 802.2 217 10.2 IEEE 802.3 CSMA/CD 219 DCAA01 2/27/06 11:17 AM Page ix Contents ix 10.3 IEEE 802.4 token bus 224 10.4 IEEE 802.5 token ring 225 10.5 Wireless LANs 228 Exercises 238 11 High-speed LANs and metropolitan area networks 240 11.1 Fibre Distributed Data Interface 240 11.2 IEEE 802.3u 244 11.3 IEEE 802.3z 246 11.4 IEEE 802.6 MAN 247 11.5 IEEE 802.17 Resilient Packet Rings 251 Exercises 251 12 Packet-switched and frame relay networks 252 12.1 Evolution of switched communications 252 12.2 X.25 packet-switched networks 255 12.3 Frame relay networks 262 12.4 Frame relay traffic management 265 Exercises 270 13 Asynchronous transfer mode 271 13.1 Asynchronous and synchronous transfer 272 13.2 ATM protocol model 272 13.3 ATM adaptation 275 13.4 Virtual connections 277 13.5 ATM service categories 279 13.6 Traffic management 281 13.7 ATM switches 288 13.8 ATM standards 290 Exercises 290 14 Internetworking 293 14.1 Internetworking requirements 293 14.2 Internetworking techniques 296 14.3 The Internet 304 14.4 Security 305 Exercises 306 15 Internet protocols 308 15.1 The TCP/IP suite 309 15.2 Internet Protocol 310 15.3 Routing protocols 318 15.4 Transport layer protocols 322 15.5 Virtual private networks 325 15.6 Real-Time Transport Protocol and Voice over IP 326 15.7 Multi Protocol Label Switching (MPLS) 329