CRC Handbook of Local Area Network Software

HANDBOOK OF

LOCAL AREA

NETWORK

SOFTWARE

HANDBOOK OF

LOCAL AREA

NETWORK

SOFTWARE

Concepts and Technology

PAULJ.FORTIER

Boca Raton London New York

CRC Press is an imprint of the

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First published 1991 by CRC Press

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PREFACE

Ever since the successful introduction of the first computer network, Arpanet, in the

late 1960s, hundreds of other computer networks have come into being. These

networks run the gamut from global world networks, national networks, metropolitan

networks, down to local area networks of various sizes and complexity.

With the continuing expansion of the number of host computers (Dec announced

the shipping of the 100,000 th V AX), workstations (Sun, Apollo), personal computers

and terminals, and the attendant increase in processing and information demands, it

can be seen how the role of the network (wide area or otherwise) has expanded and

been solidified. As such we will see more and more of these computing devices being

linked together into networks for the purpose of resource sharing, expanding avail￾ability of resources, information access, and better service to the expanding user base.

To meet the needs of this growing community Local Area Network vendors have

developed new systems and software products providing a myriad of services before

unimaginable.

Local area networks have provided a means for enterprises to expand their comput￾ing resources in a logical controlled fashion. These growing networks have given these

institutions a means to more readily and effectively utilize their most important

corporate resource; INFORMATION. This one element of networking has led to the

current information explosion.

Because of the vastly expanding requirements for computing and information

exchange and sharing, the demands for extended services from the networks has also

skyrocketed. We are seeing another revolution in the computing and technology arena

as that which occurred when operating systems first arrived. That is, ways to simplify

and control the general forms of services required by all are migrating from user

problems to systems developers (vendors) problems. The solutions need to be general

and performed at the system services level.

This systems services software will take on many forms and address diverse

computing problems. For example; information management, electronic mail, built-in

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vi HANDBOOK OF LOCAL AREA NETWORK SOFTWARE

boards, resource sharing, teleconferencing, design management, fault tolerance and

configuration management to name a few. All ofthese software elements will add new

dimensions to the LANs utility to users.

This book will be divided into two parts. The first will be an intensive section

examining the various classes of software utilized in LANs in regards to their structure

and operation. The second section will survey the available LAN software, and discuss

concepts and applications thereof.

The emphasis of this book is to provide to computer scientists, engineers, network

designers, network users, applications programmers and students, the underlying

concepts used in the design, operation and use of viable computer communications

networks. It provides these individuals with an understanding at all levels of a LANs

architecture and uses in todays computing market.

CONTENTS

Preface v

1. INTRODUCTION TO

LOCAL AREA NETWORKS 1

Why Local Area Networks? 6

Local Area Network Considerations 6

Geographic 7

Social 7

Technological 8

Hardware and Protocols 8

Media and Topology 8

Interface Units 16

NIU Standards 19

Host Devices 19

Supercomputers 21

Mainframes 22

Minicomputers 22

Workstations 22

Personal Computers and Microprocessors 23

Reference Models 23

The Application 25

Book Model 26

Local Area Networks Software 27

Overview 30

vii

viii HANDBOOK OF LOCAL AREA NETWORK SOFTWARE

2. APPLICATIONS 33

Introduction 33

User Data-Processing Functions 33

Resource Sharing 34

Resource Server 36

Examples 40

Tape Server 42

Disk File Server 45

Combined Distributed Server 46

Distributed Processing 47

Model/Simulate/Forecast/planning Software 48

Software Engineering Environments 49

Information Management 52

Graphics 52

Library Searching 53

Database Servers 54

Design 54

Control 54

Summary 55

3. SYSTEMS MANAGEMENT 57

Introduction 57

LAN Operating Systems 57

Object-Oriented Paradigm 61

Process-Based Paradigm 62

Remote Procedure Call 64

Database Management 65

User Interfaces 68

Concurrency Control 69

Update Synchronization 71

Dictionary /Directory 72

Crash Recovery 73

Integrity Checking (Consistency) 75

Security 75

Query Processing and Optimization 76

Security 78

4.

5.

CONTENTS ix

Cryptography

Ciphers

Cryptoanalysis

Summary of DES and Public-Key

Cryptosystems

Example of Public-Key Cryptosystem

Summary

Cryptography References

TRANSPORT/MONITORING

Introduction

Error Detection

Performance Monitoring

Fault Isolation

Fault Localization

Systems Management

System Availability Manager (SAM)

Configuration Manager Mode

Network Communication Manager

Reconfiguration Manager

Summary

DATA LINK/NETWORK

Introduction

RoutingIFlow Control

Flooding

Static Routing

Adaptive Routing

Flow and Congestion Control

Addressing and Routing

Address Names-Binding and Management

Introduction

Naming

Bindings

80

80

93

95

95

96

97

99

99

100

103

109

109

113

114

117

120

122

125

127

127

127

128

129

130

131

133

134

134

135

136

x HANDBOOK OF LOCAL AREA NETWORK SOFTWARE

Interflntra Network Software 137

Bridge/Gateway Addressing 138

Bridge/Gateway Routing 139

Translation 139

Summary 140

6. LAN SOFfW ARE POTPOURRI 141

Introduction 141

Physical Layer 143

Data-Link Layer 143

Network/Monitor Layer 144

Transport 145

Systems Management 145

Artsoft, Inc. 146

Banyan Systems Inc. 147

CBIS Inc. 147

Corvus Systems Inc. 148

Easynet Systems Inc. 148

IBM 148

Novell Inc. 148

Sun Microsystems Corp. 149

10 Net Communications 149

3 Com Corp. 150

Torus Systems, Inc. 150

Univation 150

Western Digital Corp. 151

Microsoft Corp. 151

Lan Database Management Products 152

Gupta Technologies 156

IBM 156

Lotus 156

Migent 157

Novell 157

Oracle 157

Sybase 158

XDB Systems 158

Empress-32 158

Informix 159

Oracle 159

CONTENTS xi

Odesta 160

Ingres 160

LAN Applications Software 161

Information Access 161

E-Mail 161

Office Productivity Packages 163

Miscellaneous Office Tools 166

Framework Software 166

Document Preparation 167

Specialized Office Support Equipment 167

LAN File Servers 168

Network Administration Software 173

Diagnostic Software 173

LAN Design Tools 179

Network Design Tools 180

Security 182

Computer-Assisted Design and Control

Management Software 183

CAD/CAM 184

Applications Development 184

Communications Software 187

Summary 190

APPENDIX: CATEGORIZATION OF

LAN SOFTWARE PRODUCTS 193

Introduction 193

Information 194

Electronic Mail 194

File/Text Transfer 195

PC-to-Mainframe Communications Servers 199

Word-Processing Software 199

Graphics Packages 199

Facsimile 201

Database Management Systems 203

Video Teleconferencing 204

xii HANDBOOK OF LOCAL AREA NETWORK SOFTWARE

Resource Sharing 204

Operating Systems 206

Distributed Data-Processing Software 206

Model/Simulate/Forecast/plan 208

Model/Simulate 209

Forecast/Plan 209

Develop/MaintainfExecute Software 210

CAD/CAM Software 210

Computer-Aided Publishing 212

Control Software 213

Summary 219

References 221

Index 225

1

INTRODUCTION TO LOCAL

AREA NETWORKS

Local area networks (LANs) continue to grow in popularity, as evidenced by the many

new LAN products and the publicity related to them. Numerous classroom courses on

the subject are offered as well as conferences and sessions dedicated to them. The

draw is the promise of using LANs to interconnect various computers and resources

into a unified system with more power and performance than is available from

conventional nondistributed approaches.

Potential users of local area networks want to share information and programs, have

increased computing power, or get at specified equipment. A LAN must provide

services and interfaces compatible with a wide array of user requirements based on

intended use. A LAN needs to be more than just a wire and connection mechanism.

It must provide upper-level services to users that aid in their overall applications,

design, development, and use-as do today's operating systems. This class of service

is the next great development opportunity. The lowest-level communications equip￾ment and protocols are standardized and readily available off the shelf, but the

upper-layer software is not so readily available. There is great opportunity for the

company that can provide products for the upper-layer needs.

How did we get where we are today? How did networks evolve? Basically, system

designers have used four techniques to interconnect computer equipment. They are:

1. Centralized

2. Decentralized

3. Distributed

4. Networked

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TAPE BANK DISK BANK

CENTRAL

PROCESSING

UNIT

Figure 1-1 Centralized Computer Interconnect.

A centralized interconnect environment is a self-contained system capable of

autonomous operation (Figure 1-1).

A centralized interconnect exhibits a master/slave relationship between the CPU

and the attached devices. The attached devices are typically strung off the I/O bus of

the computer. Data is transferred in data blocks via direct address, using the centralized

computer system's operating system synchronization and timing mechanisms. It is

engineered as a single, stand-alone entity where all devices are linked and controlled

via the central processing subsystem.

A decentralized system is a computing environment where not all the devices

(CPUs, I/O, disks, etc.) are at a single site (Figure 1-2). This class of computer

interconnection typically uses serial communications media, connecting remote sites

as if they were terminals. It uses a master/slave control relationship and ships data in

blocks, as communications in peripheral devices are done in centralized computing

systems.

Distributed interconnection is described as a collection of computers connected via

communications links and unified by a systemwide operating system (Figure 1-3).

This class of computer communications system is typified by a multiplicity of

resources (physical and logical), a systemwide operating system, services requested

by name not by location, and computing functions that are dispersed among several

physical computing elements. The system is viewed and acts as a virtual uniprocessor.

A computer network interconnection system is defined as an interconnected collec￾tion of autonomous computers (Figure 1-4) that are interconnected for the purpose of

exchanging information and services. Each computer has its own autonomous oper￾ating system, and there is no master/slave relationship. The components of such a

system are cooperatively autonomous but mutually suspicious of each other. They use

dedicated front -end processors, or special purpose input/output software and hardware

for data communications, with the unit of transfer typically being the packet. The