Applied Data Communications and Networks

Transcription

1 Applied Data Communications and Networks

2 Applied Data Communications and Networks W.Buchanan Senior Lecturer Department of EECE Napier University Edinburgh UK CHAPMAN & HALL London Weinheim. New York Tokyo Melbourne Madras

3 Published by Chapman & Hall, 2-6 Boundary Row, London SEt 8HN, UK Chapman & Hall, 2-6 Boundary Row, London SEI 8HN, UK Chapman & Hall GmbH, Pappelallee 3, Weinheim, Germany Chapman & Hall USA, 115 Fifth Avenue, New York, NY 10003, USA Chapman & Hall Japan, ITP-Japan, Kyowa Building, 3F, Hirakawacho, Chiyoda-ku, Tokyo 102, Japan Chapman & Hall Australia, 102 Dodds Street, South Melbourne, Victoria 3205, Australia Chapman & Hall India, R. Seshadri, 32 Second Main Road, CIT East, Madras , India First edition Chapman & Hall ISBN-13: DOl: / e-isbn-13: Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the UK Copyright Designs and Patents Act, 1988, this publication may not be reproduced, stored, or transmitted, in any form or by any means, without the prior permission in writing of the publishers, or in the case of reprographic reproduction only in accordance with the terms of the licences issued by the Copyright Licensing Agency in the UK, or in accordance with the terms of licences issued by the appropriate Reproduction Rights Organization outside the UK. Enquiries concerning reproduction outside the terms stated here should be sent to the publishers at the London address printed on this page. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. A catalogue record for this book is available from the British Library Printed on permanent acid-free text paper, manufactured in accordance with ANSIINISO Z and ANSIINISO Z (permanence of Paper).

4 This book is dedicated to John and Margaret whose kindness and help over the years has been worth more than money can buy.

5 Contents Preface 1. Communications systems 1.1 INTRODUCTION 1.2 COMMUNICATIONS MODEL 1.3 ELECTRONIC SIGNALS 1.4 BANDWIDTH 1.5 SIGNAL FREQUENCY CONTENT 1.6 MODULATION Amplitude modulation (AM) Frequency modulation (PM) Phase modulation (PM) Digital modulation 1.7 FREQUENCY CARRIER 1.8 MULTIPLEXING Frequency-Division Multiplexing (FDM) Time-Division Multiplexing (TDM) 1.9 NOISE AND SIGNAL DISTORTION 1.10 CAPACITY 1.11 TRANSMISSION MEDIA 1.12 EXERCISE 2. Data communications models, networks and standards xvii

6 viii Contents 2.1 COMMUNICATIONS NETWORKS 2.2 LOCAL AREA NETWORKS Why network? Maintaining a network Sharing resources Sharing disk resources (network file servers) Electronic mail Peer-to-peer communication Remote login Disadvantages and potential pitfalls of networks 2.3 OSI MODEL 2.4 COMMUNICATIONS STANDARDS AND THE OSI MODEL 2.5 STANDARDS AGENCIES 2.6 NETWORK CABLE TYPES 2.7 NETWORK TOPOLOGIES Star network Ring network Bus network 2.8 MANCHESTER CODING 2.9 EXERCISE 2.10 TUTORIAL 3. LAN: Ethernet, token ring and FOOl 3.1 INTRODUCTION 3.2 IEEE STANDARDS 3.3 LOGICAL LINK CONTROL 3.4 TOKEN RING Token ring - media access control (MAC) Token ring maintenance Token ring multi-station access units (MAU) 3.5 EmERNET Ethernet - media access control (MAC) layer Hardware Ethernet limitations Ethernet types Fast Ethernet Twisted-pair hubs Interconnection oflans 3.6 FmRE DlSTRmUTED DATA INTERCHANGE (FDDI) Applications of FDDI networks FDDI backbone network 3.7 EXERCISE

7 Contents ix 3.8 TUTORIAL LAN performance INTRODUCTION NETWORK TRAFFIC IMPROVING NETWORK PERFORMANCE Minimizing differing Ethernet standards Fan-out boxes Segment network with bridges and fan-out boxes Distributing load Provide alternative routes Remove repeaters Provide local resources Buffer networks with store and forward bridges TUTORIAL Transmission Control Protocol (TCP) and Internet Protocol (IP) INTRODUCTION TCP/IP GATEWAYS AND HOSTS FUNCTION OF me IP PROTOCOL INTERNET DATAGRAM TCPIIP INTERNETS Selecting internet addresses Format of the IP address Creating IP addresses with subnet numbers Specifying subnet masks EXAMPLE NETWORK DOMAIN NAME SYSTEM INTERNET NAMING STRUCTURE DOMAIN NAME SERVER TCP/IP COMMANDS ping ftp (file transfer protocol) telnet nslookup netstat (network statistics) route EXERCISE TUTORIAL High-level Data Link Control (HOLC) 111

8 x Contents 6.1 INTRODUCTION 6.2 HDLC PROTOCOL HDLC modes of operation HDLC frame fonnat Infonnation field Flag field Address field Control field Frame check sequence field 6.3 TRANSPARENCY 6.4 FLOW CONTROL Link connection Data flow 6.5 DERIVATIVES OF HDLC 6.6 EXERCISE 6.7 TUTORIAL 7. WAN: X.25 packet switching 7.1 INTRODUCTION 7.2 PACKET SWITCHING AND me OSI MODEL The physical layer (X.21) Data link layer (LAPB) Network (packet) layer 7.3 X.25 PACKETS Packet headers Packet types 7.4 X.25 PACKET FLOW Call set-up and clearing Data transmission and flow control The delivery bit 7.5 PACKET SWITCHING ROUTING 7.6 LOGICAL CHANNELS 7.7 X.25 NODE ADDRESSING 7.8 EXERCISE 7.9 TUTORIAL 8. Asynchronous communications: RS INTRODUCTION 8.2 COMMUNICATIONS TECHNOLOGY Connecting two nodes Terminal and communications equipment

9 Contents xi 8.3 ASCII CHARACTER CODES Format codes Communication-control characters Other codes Printable character set 8.4 ELECTRICAL CHARACTERISTICS Line voltages Electrical connections DB25S Connector DB9S connector PC connectors 8.5 FRAME FORMAT Parity Baud rate Bit stream timings 8.6 STANDARDS Standards organizations EIA standard RS-232-C EIA standard RS-449, RS-422A, RS-423A EIA standard RS LINE DRIVERS 8.8 COMMUNICATIONS BETWEEN TWO NODES Handshaking RS-232 pocket tester and break-out boxes RS-232 set-up Simple no-handshaking communications Software handshaking Hardware handshaking Two-way communications with handshaking DTE-DCE connections 8.9 PRACTICAL RS-232 PROGRAM 8.10 ASYNCHRONOUS PROTOCOLS 8.11 EXERCISE 8.12 TUTORIAL 9. Modems 9.1 INTRODUCTION 9.2 DIGITAL MODULATION Frequency shift keying (FSK) Phase shift keying (PSK) M-ary inodulation 9.3 MODEM STANDARDS 9.4 MODEM COMMANDS

10 xii Contents 9.5 MODEM CONNECTIONS 9.6 MODEM INDICATORS 9.7 TUTORIAL 10. Pulse coded modulation (PCM) 10.1 INTRODUCTION Sampling theory Quantization Coding of samples Quantization error 10.2 PCM PARAMETERS Dynamic range (DR) Signal-to-noise ratio (SNR) 10.3 SPEECH COMPRESSION 10.4 DELTA MODULATION PCM Adaptive delta modulation PCM 10.5 DIFFERENTIAL PCM (DPCM) Adaptive differential PCM (ADPCM) 10.6 PCM SYSTEMS 10.7 ALTERNATIVE MARK INVERSION (AMI) LINE CODE High density bipolar3 (HDB3) coding 10.8 TUTORIAL 11. Integrated Services Digital Network (ISDN) 11.1 INTRODUCTION 11.2 ISDN CHANNELS 11.3 ISDN PHYSICAL LAYER INTERFACING Alternative Mark Inversion (AMI) line code System connections Frame format D-channel contention 11.4 ISDN DATA LINK LAYER Address field Control field Frame check sequence 11.5 ISDN NETWORK LAYER 11.6 LOCAL AREA NETWORKS CONNECTED TO ISDN NETWORKS 11.7 TUTORIAL 12. Asynchronous Transfer Mode (ATM)

11 Contents xiii 12.1 INTRODUCTION 12.2 STATISTICAL MULTIPLEXING 12.3 ATM USER NETWORK INTERFACES (UNI) 12.4 ATM CELLS 12.5 CONNECTIONS ON AN ATM NETWORK 12.6 ATM AND THE OSI MODEL 12.7 ATM PHYSICAL LAYER 12.8 ATM FLOW CONTROL 12.9 RELIABILITY OF AN ATM NETWORK ATM PERFORMANCE PRACTICAL ATM NETWORKS EaStMAN addressing and routing TUTORIAL 13. Error control 13.1 INTRODUCTION 13.2 PARITY 13.3 CYCLIC REDUNDANCY CHECKING (CRC) 13.4 LONGITUDINAL I VERTICAL REDUNDANCY CHECKS (LRCIVRC) 13.5 HAMMING CODE 13.6 TUTORIAL 14. X-Windows 14.1 INTRODUCTION 14.2 FUNDAMENTALS OF X Server Client Communications channel 14.3 NETWORK ASPECTS OF X 14.4 HISTORY OF X 14.5 X SYSTEM PROGRAMS 14.6 TUTORIAL 15. Analysis 01 digital pulses 15.1 INTRODUCTION 15.2 REPETITIVE SIGNALS

12 xiv Contents 15.3 WAVE SYMMETRY Even symmetry Odd symmetry Half-wave symmetry FOURIER SERIES OF A REPETITIVE RECTANGULAR WAVEFORM EXAMPLES PROGRAM TO DETERMINE HARMONICS TUTORIAL Transmission lines INTRODUCTION EQUIVALENT CIRCUIT Program to determine characteristic impedance Propagation coefficient, y SPEED OF PROPAGATION TRANSMISSION LINE REFLECTIONS Reflections from resistive terminations Reflections at junctions between two transmission lines Reflections at junctions with two transmission line in parallel MATCHING TERMINATIONS OPEN AND SHORT CIRCUIT TERMINATIONS TUTORIAL Optical fibre systems INTRODUCTION LIGHT PARAMETERS Wavelength Colour Velocity of Propagation Refractive index LIGHT EMITTING DIODE (LED)! INJECTION LASER DIODE (ILD) PHOTODIODES FmRE OPTICS Introduction Theory Losses in fibre optic cables Fibre optic link TYPICAL OPTICAL FmRE CHARACTERISTICS ADVANTAGES OF FmRE OPTICS OVER COPPER CONDUCTORS TUTORIAL 306

13 Contents xv Appendix A: Practical RS-232 programming A.l INTRODUCTION A.2 ISOLATED I/O A.2.1 Inputting a byte A.2.2 Outputting a byte A.3 PROGRAMMING THE SERIAL DEVICE A.3.l Line Status Register (LSR) A.3.2 Line Control Register (LCR) A.3.3 Register addresses A.3.4 Programming RS232 via ODS A.4 PROGRAMS A.5 USING BIOS A.6 TUTORIAL A.7 PROJECTS A.7.1 Project 1: Half-duplex link A.7.2 Project 2: Full-duplex link A.7.3 Project 3: Simulated software handshaking A.7.4 Project 4: File transfer Appendix B: Data communications standards B.l STANDARDS B.2 INTERNATIONAL ALPHABET NO.5 Appendix C: Data communications connections C.l RS 232C INTERFACE C.2 RS-449 INTERFACE Appendix D: Ethernet voltages and Fast Ethernet D.l ETHERNET VOLTAGE LEVELS D.2 FAST ETHERNET AND l00vg ANYLAN Fast Ethernet loovg-any LAN Migration from Ethernet to Fast Ethernet or loovg-anylan Network performance Glossary Common abbreviations Index

14 Preface The usage of data communications and computer networks are ever increasing. It is one of the few technological areas which brings benefits to most of the countries and the peoples of the world. Without it many industries could not exist. It is the objective of this book to discuss data communications in a readable form that students and professionals all over the world can understand. As much as possible the text uses diagrams to illustrate key points. Most currently available data communications books take their viewpoint from either a computer scientists top-down approach or from an electronic engineers bottom-up approach. This book takes a practical approach and supports it with a theoretical background to create a textbook which can be used by electronic engineers, computer engineers, computer scientists and industry professionals. It discusses most of the current and future key data communications technologies, including: Data Communications Standards and Models; Local Area Networks (Ethernet, Token Ring and FDDI); Transmission Control ProtocollInternet Protocol (TCPIIP); High-level Data Link Control (HDLC); X.25 Packet-switching; Asynchronous Communications (RS-232) and Modems; Pulse Coded Modulation (PCM); Integrated Digital Services Network (ISDN); Asynchronous Transfer Mode (ATM); Error Control; X-Windows. The chapters are ordered in a possible structure for the presentation of the material and have not been sectioned into data communications areas. xvii

15 xviii Preface There are six main areas covered and these can be linked with the chapters to give the following: Introduction to communications systems (chapters 1 and 2); LAN s and internetworking (chapters 3, 4 and 5); W ANs (chapters 7,8,9, 10 and 11); Current and future provision (chapters 12 and 17); Physical layer - signalling and media (chapters 15, 16 and 17); Related! pervasive issues (chapters 6 and 13). One of the main objects of the book is to use practical examples to illustrate key areas. These include: the analysis of a real-life university Ethernet and Token Ring computer network, showing how interconnected networks communicate; the analysis of state-of-the-art technologies such as FDDI and A TM with reference to a practical Metropolitan Area Network; practical data communications programs, in C, for serial communications; practical examples of communications over the Internet; the necessary information on how to set-up computers for TCPIIP communications. The text also contains some multiple choice exercises which can be used by a lecturer to revise the material presented or can be used at the beginning of a tutorial session. Requests for technical support can be sent to the author using the address: w.buchanan@central.napier.ac.uk Book updates, together with the software in the book, and other related information can be found on the WWW page:

16 Preface xix Finally, I would like to thank my commissioning editor Dave Hatter for his support of this project and for his dynamic energy. I would also like to thank Ian Marshall, in the School of Information Systems at University of East Anglia, for his expert knowledge and comments on the original proposal. His feedback was most helpful during the writing of this book.