Ethernet Networking- P1 pdf

Clients, Servers, and Peers 7 Data Communications Protocols 9 Layered Protocols 11 Another Word on Protocol Stacks 13 Network Operating Systems 14 What Ethernet Really Means 15... iv Con

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Library of Congress Cataloging-in-Publication Data

Harrington, Jan L

Ethernet networking for the small office and professional home office / Jan L Harrington

p cm

Includes bibliographical references and index

ISBN-13:978-0-12-373744-1 (alk paper)

ISBN-10:0-12-373744-3 (alk paper)

1 Ethernet (Local area network system) 2 Home offices 3 Business enterprisesmComputer

I Working together to grow

libraries in developing countries

Clients, Servers, and Peers 7

Data Communications Protocols 9

Layered Protocols 11

Another Word on Protocol Stacks 13

Network Operating Systems 14

What Ethernet Really Means 15

iv Contents

Chapter 2: H o w TCP/IP and Ethemet W o r k 21

Network Data Transmission 22

Major TCP/IP Protocols 23

The Operation of a Protocol Stack 23

The Application Layer 24

The Transport Layer 25

The Internet Layer 29

The Logical Link Control Layer 31

The Ethernet MAC Protocol 33

Ethernet Frames 33

Ethernet Media Access 35

Alternative Protocol Stacks 38

Part Two: Design and Connectivity

Chapter 3: Fast and Gigabit Ethernet Media and Standards 41

UTP Cabling 41

UTP Standards 42

UTP Cabling Lengths 44

UTP Jack Wiring 46

Fiber Optic Cabling 47

Single versus Multimode Fiber Optics 48

Fiber Optic Cable Bundles 49

Fast Ethernet Standards 50

Creating a Simple Switched Segment 68

Creating Hierarchical Switched Configurations 68

Contents

Cabling Issues 73

Looping Issues 74

Where Do You Put It? Wiring Closets, Walls, Floors,

and Ceilings Oh, My! 75

Appendix: Wiring RJ-45 Plugs and Connectors 81

C h a p t e r 5: C o n n e c t i n g to the Internet 89

ISPs and IP Addresses 89

Internet Connection Protocols 91

Point-to-Point Protocol 91

Point-to-Point Protocol Over Ethernet for Cable and DSL 92 Dial-up Connections 92

Modems and POTS 92

Integrated Services Digital Network 97

Domain Names and DNS 125

Making Routing Decisions 127

Routers and the TCP/IP Protocol Stack 127

vi Contents

C h a p t e r 7: Integrating Wireless T r a n s m i s s i o n s 141

Wireless MAC Protocol versus Ethernet MAC Protocol 142

Wireless Speeds and Standards 142

Wireless Access Points 144

Service Set Identifiers 144

Adding Access Points to a Wired Network 147

Wireless Security Issues 148

WEP 148

WiFi Protected Access 150

Part Three: Making the Network Work

C h a p t e r 8: N e t w o r k Servers: Files, the Web, and Printers

Client-Server versus Peer-to-Peer File Sharing 156

Server Operating Systems 157

File Server Services 157

Widely Used Server Operating Systems 158

Web Servers 166

Print Serving 167

Shared Printer Architectures 168

Occasional Printer Sharing 168

Printing through a Server 174

For Very Small Networks: Network Magic 186

For Larger Networks: LANsurveyor 189

Real-Time Monitoring and Packet Sniffing 193

Contents vii

Chapter 10: Security Issues 203

Security Threats to Home and Small Offices 204

Intrusion Detection Systems 241

Virtual Private Networks 244

Security Resources 248

Professional Security Update Sites 248

Other Sites of Interest 249

Chapter 11: N e t w o r k Design and Simulation Software 251

Network Design Tools 252

The Network Hierarchy 253

Choosing and Configuring Network Devices 254

Linking Network Devices 263

Simulating Network Traffic 267

Assigning Traffic Loads 268

Running Simulations 270

Documenting the Network Design 272

Part Four: Ethernet Solution Examples

viii Contents

Chapter 14: Network Example 3" Small Law Firm 289

The Internet, the Backbone, and Equipment Rooms 291

Between the Floors 293

The Fifth-Floor Server Room 294

The Fourth-Floor Wiring Closet 295

Connecting End-User Devices 295

Security Considerations 297

A p p e n d i x A: O l d e r E t h e r n e t S t a n d a r d s 299

Thick Coaxial Cable (10BASE5) 300

Thin Coaxial Cable (10BASE2) 301

A network can be as small as two computers and a printer located in the comer of a family room or as large as the entire world Although much of the theory of data transmission is the same, regardless of the network's size, the specifics of the hardware and software are somewhat different, and no single book could describe all of it (unless you wanted to move the book with a forklift, that is)

This book focuses on professional networks that are in either a small com- mercial space or a home Today, such small networks use a single physical

ix

Preface

s t a n d a r d ~ E t h e m e t ~ t h a t was designed primarily for networks that are contained within a single physical location (Remote users can access the network through interconnections to other networks made, for example, by the Internet, but the permanent parts of the network are typically housed in one building or a group of buildings located in close physical proximity.)

If you need to design, install, and manage a network in such an environ- ment, then this book will give you an understanding of the technology in- volved in an Ethernet network It will teach you how Ethernets work and what you need to put one together

Probably the toughest part of understanding networks is the jargon If you're unfamiliar with networking terminology and acronyms, then a sen- tence like "To hook up to the legacy 10BASE2 segment, you connect the

B NC connector to the NIC" is meaningless gibberish One of the major goals of this book is therefore to demystify the secret language of networks for you so that you can speak in acronyms just like the rest of the network gurus

One of my greatest frustrations with networking books is that they often focus on only one layer of the network To be technically accurate, "Ether- net" refers to only one part of the hardware However, if you are going to

be responsible for an Ethernet network, then you need to know a lot more than just how to choose and configure your network hardware You also need information about the devices you can attach to your network and the software you will need to make it all work In addition, you will probably want to give some thought to managing the network And most important, you will want to look at your network in terms of security; even if your net- work's only outside connection is to the Internet, you are vulnerable to a variety of system attacks! This book goes beyond the hardware aspects of Ethernet to look at the entire network from bottom to top

Another major concem with writing a book of this type is the level of tech- nical detail How much do you really need or want to know about how net- work signals are transmitted? If you want to know which specific signals are carried on which wires within a network cable, then this is not the book for you However, if you want enough technical detail to be able to make intelligent choices about what types of transmission media to use for your

Preface xi

network and the way to interconnect the parts of that network, then you are holding the fight volume

What You Need to Know

To understand the material in this book, you need a thorough knowledge

of basic PC hardware and at least one PC operating s y s t e m ~ f o r example, Windows 2000 or newer, some flavor of UNIX, or Mac OS X I have an unabashed preference for the latter, but we each go where our experience and hearts take us You should also be comfortable with basic PC software such as word processors, e-mail, and World Wide Web browsers

Acknowledgments

Writing a book for Morgan Kaufmann is an absolute delight I'd like to thank both Rick Adams, my editor, and Rachel Roumeliotis, his assistant, for all their help And, of course, much thanks to the project manager, Marilyn Rash; the copy editor, Joan Flaherty; and the proofreader, Debbie Prato

In addition, a large number of vendors gave us permission to use illustra- tions and photos of their products My thanks go out to all of them (You can find contact information for those vendors in Appendix C.)

http ://www.blackgryphon.info

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Introduction

The first two chapters of this book present some introductory conceptual material about networking and Ethernet By the time you finish reading them, you will understand exactly what Ethernet is and the part it plays in your network

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Introduction

One of the biggest problems when discussing networking is knowing where

to start The subject of computer networks is one of those areas for which you have to "know everything to do anything." Usually, the easiest way to ease into the topic is to begin with some basic networking terminology and then look at exactly what it means when we use the word Ethernet

Anatomy of a Network

A computer network is a combination of hardware and software that allows computers and other devices (for example, printers and file servers) to communicate with one another through some form of telecommunications media (for example, telephone lines)

Introduction

Note: As you read material about data communications,

you may see references to POTS lines POTS stands for

"plain old telephone service."

Networks can be classified by the distances they cover and whether they include technology like that used on the Internet:

LAN (local area network): A network confined to a small geo- graphic a r e a ~ s u c h as a floor, single building, or group of buildings in close physical proximity (for example, a college campus or an office p a r k ) ~ that is almost always owned by a single organization The organization owns the telecommuni- cations lines as well as the hardware connected to the network

Intranet: A network (LAN or WAN) owned by a single compa-

ny that uses technology similar to that used on the Internet MAN (metropolitan area network): An outdated term describ- ing a network that covers an entire city Today, the concept of

a MAN has been replaced largely by the WAN

WAN (wide area network): A network that covers a large geo- graphic area, such as a city, state, or one or more countries Al- though a WAN may be owned by a single organization, the network usually includes telecommunications media (for ex- ample, telephone lines or satellite transmissions) that are leased from commercial telecommunications providers

Internet: When in all lowercase letters (internet), a WAN that

connects multiple networks into a larger network When writ- ten with a leading uppercase letter (Internet), it is the global

network that supports the World Wide Web Because of the po- tential for confusion between internet and Internet, the term in- ternet is rarely used today

The technologies we will be discussing in this book are applicable to LANs and intranets Although we will discuss connecting LANs to the Internet, the focus is on creating and maintaining networks that serve small

to medium-size workgroups in small offices, regardless of whether they are located in commercial buildings or homes

Anatomy of a Network

Network Components

A computer network is made up of three major components:

Hardware: The equipment that connects to the network Typi-

cally, this includes computers, printers, and modems Each dis- tinct piece of hardware on a network is known as a node In

addition to the hardware that actually uses the network to trans- fer data to perform work for an organization, a network may contain specialty hardware that helps manage the network and connects it to other networks Such hardware includes routers, bridges, switches, hubs, repeaters, and gateways You will read about network hardware of these types throughout this book Each device on a network is identified by two types of ad- dresses The first is a hardware address that physically identi- fies the piece of equipment In many cases, this address is set

by the hardware manufacturer and is not easily changed These addresses, known as MAC (media access control) addresses,

must be unique throughout the network segment If a manufac- turer happens to produce hardware with duplicated MAC ad- dresses, then a network segment that uses that hardware cannot function

The second type of address is a software address that is add-

ed by the software that handles data transmission The software address can be changed as needed

Software: The programs that manage the transfer of data

throughout the network, most commonly known as network operating systems (NOS) Current desktop operating s y s t e m s ~

Windows, Mac OS X, and L i n u x ~ a r e capable of network operations fight out of the box However, they cannot provide the robust, centralized, shared services such as file sharing needed by commercial networks Most organizations therefore end up investing in specialized network operating system soft- ware to provide services such as file sharing, user management, security, and directory management

Transmission media: The cables or wireless signals that carry

data from one node to another

In addition, there must be interfaces between the hardware and the network These often take the form of expansion boards that are added to pieces of