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Practical Data Communications, Second Edition PDF

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PracticalDataCommunications,SecondEdition.RogerL.Freeman Copyright(cid:1)1995,2001RogerL.Freeman PublishedbyJohnWiley&Sons,Inc. ISBNs:0-471-39302-9ŽHardback.;0-471-39273-1ŽPaper.;0-471-22422-7ŽElectronic. Practical Data Communications Practical Data Communications Second Edition Roger L. Freeman AWiley-IntersciencePublication JOHNWILEY&SONS,INC. New York (cid:1) Chichester (cid:1) Weinheim (cid:1) Brisbane (cid:1) Singapore (cid:1) Toronto Designations used bycompanies todistinguish their products are often claimed as trademarks. Inallinstances whereJohnWiley&Sons,Inc.,isawareofaclaim,theproductnames appearininitialcapitalorALLCAPITALLETTERS.Readers,however,shouldcontactthe appropriate companiesformorecompleteinformationregardingtrademarksandregistration. Copyright(cid:1)1995,2001byRogerL.Freeman.Allrightsreserved. Published byJohnWiley&Sons,Inc. Nopartofthispublicationmaybereproduced, storedinaretrievalsystemortransmitted in any form or by any means, electronic or mechanical, including uploading, downloading, printing,decompiling,recordingorotherwise, exceptaspermittedunderSections107or 108ofthe1976UnitedStatesCopyrightAct,withoutthepriorwrittenpermissionofthe Publisher. RequeststothePublisher forpermissionshouldbeaddressed tothe PermissionsDepartment, JohnWiley&Sons,Inc.,605ThirdAvenue,NewYork,NY 10158-0012,Ž212.850-6011,faxŽ212.850-6008,E-Mail:PERMREQ&WILEY.COM. This publication is designed toprovideaccurate and authoritative information in regard tothe subject matter covered. It is sold with the understanding that the publisher is not engaged in renderingprofessionalservices.Ifprofessionaladviceorotherexpertassistance isrequired,the servicesofacompetentprofessionalpersonshouldbesought. ISBN0-471-22422-7 ThistitleisalsoavailableinprintasISBN0-471-39302-9Žcloth.and0-471-39273-1Žpaper.. FormoreinformationaboutWileyproducts,visitourwebsiteatwww.Wiley.com. For my son,Bob CONTENTS Preface xxix Chapter 1 The Enterprise Network Environment 1 1.1 Enterprise Networks 1 1.2 Types of Network Topology 3 1.3 Network Access: An Overview 6 1.4 Initial Network Design Considerations 7 1.5 Connection-Oriented and Connectionless Service 8 1.6 Data Protocols: Key to Network Operation 8 1.6.1 Introduction 8 1.6.2 Basic Protocol Functions 9 References 11 Chapter 2 The OSI Model and the Data-LinkLayer 13 2.1 Introduction 13 2.2 Layering 14 2.2.1 Notation 14 2.2.2 Basic Structuring Technique 14 2.3 Type and Instance 15 2.4 Possible Sublayers 16 2.5 Data Units 17 2.6 Specific Layers of the OSI Reference Model 18 2.7 Layer Descriptions 19 2.8 Specific Comments on OSI 33 2.8.1 General 33 2.9 Discussion of OSI Layers 1(cid:1)4 34 2.9.1 The Physical Layer ŽLayer 1. 34 2.9.2 The Data-Link Layer ŽLayer 2. 35 2.9.3 The Network Layer ŽLayer 3. 37 vii viii CONTENTS 2.9.4 Internet Protocol ŽIP. and Gateway Layer ŽLayer 3.5. 37 2.9.5 The Transport Layer ŽLayer 4. 38 2.10 Procedural Versus Electrical 39 2.10.1 Narrative 39 References 39 Chapter 3 High-LevelData-LinkControl(HDLC)Typical Data-LinkLayer Protocol 41 3.1 Introduction 41 3.2 Stations and Configurations 42 3.3 Modes of Operation Used with HDLC 43 3.4 HDLC Frame Structure 43 3.4.1 Sequence Numbering in HDLC 45 3.4.2 The PollrFinal Bit 47 3.4.3 Supervisory Frames 47 3.4.4 Unnumbered ŽU. Frames 48 3.4.5 Information Field 48 3.4.6 Frame Check Sequence ŽFCS. Field 48 3.5 Commands and Responses 49 3.5.1 Mode-Setting Commands 49 3.5.2 Miscellaneous Commands 51 3.5.3 ResponsestoUnnumberedCommands 51 3.6 Frame Operation 52 3.7 Error Recovery 53 3.8 Other Station Modes 54 3.9 SDLC Variations with HDLC 55 References 55 Chapter 4 Data Network Operations 57 4.1 Chapter Objective 57 4.2 General RequirementsfortheInterchange of Data 57 4.3 Discussion of Issues and Requirements 58 4.3.1 PathwayŽs. ExistŽs. 58 4.3.2 Access to the Pathway 59 4.3.3 Directing theDataMessagestoIts Intended UserŽs. 59 4.3.4 Data Urgency 59 4.3.5 Maintenance of Data Integrity 60 4.4 Error Detection Schemes 61 4.4.1 Parity Checks 61 4.4.2 Cyclic Redundancy Check ŽCRC. 62 CONTENTS ix 4.5 Error Correction Schemes 64 4.5.1 Automatic Repeat Request ŽARQ. 64 4.5.2 Forward Error Correction ŽFEC. 65 4.6 Data Switching 67 4.6.1 Philosophyof‘‘DataSignaling’’Versus Telephone Signaling 69 4.6.2 SmartBridges,Routers,andSwitching Hubs 71 References 71 Chapter 5 Data TransmissionI 73 5.1 Electrical Communication of Information 73 5.2 The Bit and Binary Transmission of Information 73 5.3 Binary Codes for Data Communication 76 5.4 Electrical Bit Decisions 79 5.5 Electrical Representation of Binary Data 82 5.5.1 Neutral and Polar Waveforms 82 5.5.2 Waveforms and Line Codes 83 5.6 Binary Conventions 84 5.7 Bit-Parallel and Bit-Serial 85 5.8 Baseband 86 5.9 Data Rate 87 5.9.1 Error Rate 87 References 88 Chapter 6 Data TransmissionII 89 6.1 Interpreting a Serial Stream of Bits 89 6.1.1 The Problem 89 6.1.2 Start(cid:1)Stop Transmission 89 6.1.3 Synchronous Transmission 91 6.2 Timing Distortion in a Serial Bit Stream 93 6.3 The Transmission of Digital Data 94 6.3.1 Baseband Transmission 94 6.3.2 Transmission ofDataoverLonger Distances 95 6.3.2.1 The Voice Channel 95 6.3.2.2 Modems 95 6.3.2.3 VoiceChannel Impairments to Data Transmission 97 6.3.3 Data Circuit Performance 102 6.3.3.1 Introduction to Error Performance 102 x CONTENTS 6.3.3.2 ErrorPerformancefromanITU-T Perspective 103 6.3.3.3 ErrorPerformancefroma Bellcore Perspective 107 6.4 Interface at the Physical Layer 107 6.4.1 Introduction 107 6.4.2 The DTE(cid:1)DCE Interface 108 6.4.2.1 EIArTIA-232 Electrical Interface 110 6.4.2.2 Functional Description ofSelected Interchange Circuits 112 6.4.2.3 EIArTIAInterface Standards: EIArTIA-530,EIArTIA-422,and EIArTIA-423 114 6.5 The Question of Bandwidth 116 6.5.1 Bandwidth Versus Bit Rate 116 6.5.2 Bandwidth Defined 116 6.5.3 First andSecondBandwidth Approximations 116 6.5.4 Shannon 117 6.5.5 Summary 118 References 118 Chapter 7 The TelecommunicationsNetwork asa Vehicle for Data Transport 121 7.1 The Public Switched Telecommunication Network 121 7.1.1 Introduction 121 7.1.2 AccesstothePSTN:TheSubscriber Network 122 7.2 Introduction to Digital Networks 123 7.2.1 Rationale 123 7.2.2 Development of a PCM Signal 123 7.2.3 The Concept of Frame 131 7.2.4 The Line Code 134 7.2.5 Regenerative Repeaters 135 7.2.6 Higher-Order PCM Multiplex Systems 136 7.2.7 Line Rates and Codes 139 7.3 Brief Overview of Digital Switching 139 7.3.1 Advantages and Issues of PCM Switching 139 7.3.2 Approaches to PCM Switching 140 CONTENTS xi 7.3.3 Time Switch 140 7.3.4 Space Switch 142 7.3.5 Time(cid:1)Space(cid:1)Time Switch 144 7.3.6 Space(cid:1)Time(cid:1)Space Switch 146 7.4 Digital Network Structure 146 7.5 Digital Network Impairments and Performance Requirements 147 7.5.1 Error Performance 147 7.5.2 Slips 147 7.5.2.1 Definition 147 7.5.2.2 North American Slip Objectives 148 7.5.2.3 CCITT Slip Objectives 148 7.6 Data Transmission on the Digital Network 149 7.6.1 The Problem 149 7.6.2 Some Solutions 149 7.6.2.1 The North American Digital Data System ŽDDS. 150 7.6.2.2 Bit Integrity in a Time Slot 150 7.7 Interconnects and Bypass 151 7.8 Bypass in Economically Evolving Nations 152 References 152 Chapter 8 The Transmissionof Data over the Analog Voice Channel 155 8.1 Background 155 8.2 Two-Wire Versus Four-Wire Operation 156 8.2.1 WhatIsTwo-WireandFour-Wire Operation? 156 8.2.2 Two-Wire Transmission 156 8.2.3 Four-Wire Transmission 156 8.3 Echo and Singing: Telecommunication Network Impairments 159 8.4 Amplitude Distortion and Phase Distortion 159 8.4.1 Introduction 159 8.4.2 Amplitude Distortion 160 8.4.3 Phase Distortion 160 8.4.4 Conditioning and Equalization 161 8.5 Data Modems 165 8.5.1 Where We Are and Where We Are Going 165 8.5.2 Getting More Bits per Hertz 165 8.5.3 Specific High-Speed Modems 168 xii CONTENTS 8.5.4 Scrambling and Its Rationale 174 8.5.5 Introduction to Trellis-Coded Modulation ŽTCM. 176 8.5.6 The V.34 Modem: 28,8000 bps and 33,600 bps 178 8.5.6.1 General 178 8.5.6.2 Selected Definitions 179 8.5.6.3 AnOverviewofSelected Key Areas of Modem Operation 179 8.5.6.4 Framing 183 8.5.6.5 Encoder 186 8.5.7 The V.90 Modem(cid:2)Maximum Data Rate: 56 kbps 187 8.5.7.1 Principal Characteristics 187 8.5.7.2 Definitions 188 8.5.7.3 Overview of V.90 Operation 191 8.5.7.4 V.90 Encoder 191 8.5.7.5 Mapping Parameters 192 8.5.7.6 Input Bit Parsing 192 8.5.7.7 Modulus Encoder 192 8.5.7.8 Mapper 194 8.5.7.9 Spectral Shaping 194 8.5.7.10 Spectral Shaper 196 8.5.7.11 Spectral Shape Filter 198 8.5.7.12 Sign Assignment 198 8.5.7.13 MUX 198 8.5.7.14 Analog Modem 198 References 200 Chapter 9 Data Communications in the Office Environment, Part 1 203 9.1 Introduction 203 9.2 Distinguishing Characteristics of LANs 204 9.3 How LAN Protocols Relate to OSI 206 9.4 Logical Link Control ŽLLC. 206 9.4.1 LLCSublayer Services and Primitives 208 9.4.1.1 UnacknowledgedConnectionless- Mode Service 209 9.4.1.2 Connection-Mode Service 209 9.4.1.3 Type1andType2Operation 210 9.4.2 LLC PDU Structure 211 9.4.2.1 Overview 211 9.4.2.2 Control Field Formats 213

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