Computer Networks and Their Protocols

520 Pages·1979·25.043 MB·English

by  D. W. Davies

5 0605 01047078 4
^*
Computer Networks
and
Their Protocols
WILEY SERIES IN COMPUTING
Consulting Editor
Professor D. W. Barron, Department ofMathematics. Southampton
University
—
Numerical Control Mathematics and Applications
P. Bezier
Communication Networks for Computers
D. W. Davies and D. L. A. Barber
Macro Processors and Techniques for Portable Software
P. J. Brown
A Practical Guide to Algol 68
Frank G. Pagan
Programs and Machines
Richard Bird
The Codasyl Approach to Data Base Management
T. William Olle
Computer Networks and their Protocols
D. W. Davies, D. LA. Barber. W. L Price and C M. Solomonides
Algorithms: Their Complexity and Efficiency
Lydia Kronsjo
Data Structures and Operating Systems
Teodor Rus
Computer Networks
and
Their Protocols
D.W. Davies
National Physical Laboratory, Teddington
D.L.A. Barber
Director. European Informatics Network
W.L. Price and CM. Solomonides
National Physical Laboratory, Teddington
A Wiley-Interscience Publication
JOHN WILEY & SONS
Chichester New York Brisbane Toronto
• • •
Copyright © 1979 by John Wiley & Sons Ltd.
All rights reserved.
No part ofthis book may be reproduced by any means, nor
transmitted, nor translated into a machine language without
the written permission ofthe publisher.
Library ofCongress Cataloging in Publication Data:
Main entry under title:
Computer networks and their protocols.
'A Wiley-lnterscience publication.'
Includes bibliographical references and index.
1. Computer networks. I. Davies, Donald Watts.
TK5105.5.C6492 001.6.44.04 78-21973
ISBN 471 99750
1
Printed in Great Britain
by Unwin Brothers Limited
The Gresham Press, Old Woking, Surrey.
A member ofthe Staples Printing Group.
Contents
Preface xiii
Chapter 1. Computer Networks 1
1.1 Computer networks and their subsystems 1
The communication subsystem 2
1.2 Network protocols 4
Protocols and interfaces 4
Hierarchies of protocols 5
1.3 Forms of subnetwork 7
Transmission technology 8
Switching and multiplexing by circuits and packets 10
1.4 The user's view of the computer network 12
Incompatibility 13
Network information service 15
Network job control language 16
The network access machine 18
1.5 The public data communication network 21
CCITT recommendations for public data networks 22
The virtues of a public data network 23
The vices of a public data network 25
1.6 Sources of network traffic 26
Funds transfer 27
The extension of word processing 32
The information society 33
References 36
Chapter 2. Packet Switching 38
2.1 Introduction 38
COMPUTER NETWORKS ANDTHEIR PROTOCOLS
Vi
2.2 Switching, concentration and multiplexing 38
Multiplexing 41
Demand multiplexing 43
2.3 Store-and-forward applied to messages 44
Error control 45
Delay in message switching 46
2.4 The origins of packet switching 46
The Rand Corporation reports 47
The first packet-switched systems 48
The packet concept 50
Packets, circuits and messages 51
2.5 The packet-switched communication subsystem 53
Addressing and routing 55
The need for flow control 57
Message reassembly 57
Packet sequence 58
2.6 The virtual circuit 59
The virtual call 60
The need for a datagram service 60
Implementation of the virtual call 61
The permanent virtual circuit 64
2.7 Special features in packet networks 64
Delivery confirmation 65
Trace packets 66
Echo 66
Drop 66
Network statistics 67
The network diagnostic centre 67
Charging for network use 68
The closed user group 69
2.8 Why packet switching? 69
The virtues of circuit switching 70
Integrated networks 71
2.9 Packet-switched networks in practice 72
References 74
Chapter 3. Routing 77
3.1 Introduction 77
3.2 Taxonomy of routing algorithms 82