`
`Computer Networking Essentials
`
`DebraLittlejohn Shinder
`
`Cise
`0 SYSTEMS
`
`hoa
`Cisco Press
`
`Cisco Press
`201 West 103rd Street
`Indianapolis, IN 46290 USA
`
`001
`
`AppleInc.
`APL1117
`U.S. Patent No. 8,724,622
`
`001
`
`Apple Inc.
`APL1117
`U.S. Patent No. 8,724,622
`
`
`
`Computer Networking Essentials
`Debra Littlejohn Shinder
`Copyright © 2001 Cisco Systems, Inc.
`Cisco Press logois a trademark of Cisco Systems,Inc.
`Published by:
`Cisco Press
`201 West 103rd Street
`Indianapolis, IN 46290 USA
`All rights reserved. Nopart of this book may be reproduced ortransmitted in any form or by any means,electronic
`or mechanical, including photocopying, recording, or by any information storage and retrieval system, without writ-
`ten permission from the publisher, exceptfor the inclusion ofbrief quotations in a review.
`Printed in the United States of America 1234567890
`Library of Congress Cataloging-in-Publication Number: 2001090429
`ISBN: 1-58713-038-6
`
`Trademark Acknowledgments
`All terms mentioned in this book that are known to be trademarksor service marks have been appropriately capital-
`ized. Cisco Press or Cisco Systems,Inc., cannotattest to the accuracy ofthis information. Useofa term in this book
`should notbe regardedas affecting the validity of any trademark or service mark.
`
`Warning and Disclaimer
`This bookis designed to provide information about basic networking and operating system technologies. Every
`effort has been made to make this book as complete and as accurate as possible, but no warrantyorfitness is
`implied.
`The informationis provided on an “asis” basis. The author, Cisco Press, and Cisco Systems,Inc., shall have neither
`liability nor responsibility to any person or entity with respectto any loss or damagesarising from the information
`containedin this bookor from theuseof the discs or programs that may accompanyit.
`The opinions expressed in this book belongto the author and are not necessarily those of Cisco Systems,Inc.
`
`Cn.
`
`COPY.
`
`
`
`HAY}2°4 2001
`CPYRIGHT OF
`
`As
`
`
`
`
`
`002
`
`002
`
`
`
`
`
`Contents
`
`Part |
`Chapter1
`
`Introduction to Networking Concepts 3
`Introduction to PC Networking
`5
`5
`A Brief History of PC Networking
`The First Communications Networks
`Disadvantages of Standalone Systems
`WhatIs a Network, Anyway?
`11
`Why Network Computers?
`11
`Benefits of Getting Connected
`The Birth of the Internet
`13
`The Cost of Technology: More and More for Less and Less
`PC Networking Today
`16
`16
`Home Computing
`16
`WebPresence and E-commerce
`High-Performance Business Solutions
`Online Learning
`17
`
`6
`10
`
`16
`
`12
`
`15
`
`17
`
`17
`Tomorrow’s Networks
`*Smart” Appliances and Homes
`Phoning Home
`18
`19
`The Wired Workplace
`20
`Schools of the Future
`20
`Networking Health Care
`Technology and the Law 21
`Intergalactic Networking?
`21
`A Brief Overview of Networking Terminology
`Concept-Related Terminology
`22
`Network Hardware-Related Terminology
`Software-Related Terminology
`23
`24
`Design and Topology Terminology
`24
`Measurement-Related Terminology
`What This Book Covers and WhatIt Doesn’t
`
`21
`
`22
`
`25
`
`26
`Networking Certifications
`26
`Vendor-Specific Certifications
`Non-Vendor-Specific Certifications
`This Book and Certification
`27
`
`26
`
`003
`
`003
`
`
`
`
`
`Summary
`
`27
`
`Further Reading
`
`28
`
`Review Questions
`
`28
`
`Chapter 2
`
`Categorizing Networks 33
`
`Categorizing Networks by Physical Scope
`Characteristics of aLAN 34
`Characteristics ofa MAN 35
`Characteristics ofa WAN 37
`
`33
`
`Categorizing Networks by Administrative Method
`Servers and Clients
`39
`Characteristics of Peer-to-Peer Networks
`Characteristics of Server-Based Networks
`
`44
`47
`
`38
`
`Categorizing Networks by NOS 49
`Windows Networks
`50
`NetWare Networks
`50
`UNIX Networks
`50
`Hybrid Networks
`51
`
`Categorizing Networks by Protocol
`NetBEUI Networks
`52
`IPX/SPX Networks
`52
`TCP/IP Networks
`53
`Other LAN Protocols Used in Networks
`
`52
`
`53
`
`54
`
`Categorizing Networks by Topology
`Linear Bus Networks
`55
`Ring Networks
`56
`Star Bus Networks
`Mesh Networks
`59
`Hybrid Topologies
`
`60
`
`57
`
`Categorizing Networks by Architecture
`Ethernet Networks
`62
`Token Ring Networks
`AppleTalk Networks
`ARCnet Networks
`
`67
`68
`
`68
`
`61
`
`Summary
`
`70
`
`Further Reading
`
`70
`
`Review Questions
`
`71
`
`004
`
`004
`
`
`
`xi
`
`
`Chapter 3
`
`Networking Concepts, Models, and Standards
`
`75
`
`Computer Communication Concepts
`The Language of the Machine
`76
`Common Numbering Systems
`76
`Using Packets
`80
`A Layered Communication Process
`
`75
`
`82
`
`84
`Networking Models
`The Purpose of Models
`The OSI Model
`85
`The DoD Model
`97
`Vendor-Specific Models
`
`84 ~
`
`99
`
`Networking Standards and Specifications
`WhyStandardize?
`100
`Standards-Setting Bodies
`
`100
`
`99
`
`Summary
`
`104
`
`Further Reading
`
`104
`
`Chapter4
`
`Review Questions
`105
`Networking Communications Methods
`
`109
`
`116
`
`109
`
`112
`
`Signaling Methods and Characteristics
`Analog and Digital
`109
`Baseband and Broadband
`Multiplexing
`113
`115
`Asynchronous and Synchronous Transmission
`Simplex, Half-Duplex, and Full-Duplex Transmission
`Signaling and Communications Problems
`118
`Electromagnetic Interference
`119
`Radio FrequencyInterference
`119
`Crosstalk
`119
`Attenuation
`120
`Bandwidth Capacity Issues
`
`121
`
`121
`
`Media Access Methods
`CSMA/CD 122
`CSMA/CA 123
`123
`Token Passing
`DemandPriority 125
`
`Summary
`
`126
`
`Further Reading
`
`126
`
`Review Questions
`
`127
`
`005
`
`005
`
`
`
`xii
`
`Chapter5
`
`LAN Links
`
`131
`
`132
`Ethernet
`132
`10Base2
`134
`10Base5
`10BaseT 136
`100BaseX 137
`1000BaseT 137
`The Structure of an Ethernet Frame
`Rules of Ethernet Engagement
`139
`Summary of Ethernet Characteristics
`
`138
`
`142
`
`142
`Token Ring
`143
`Token Ring Topology
`The Token Ring Communication Process
`Token Ring Hardware Components
`144
`Advantages of Token Ring
`145
`Disadvantages of Token Ring
`145
`The Structure of the Token Ring Frame
`Rules of the Ring
`147
`Summary of Token Ring Characteristics
`
`143
`
`146
`
`147
`
`147
`FDDI_
`147
`How FDDI Works
`148
`FDDI Specifications
`149
`Advantages of FDDI
`149
`Disadvantages of FDDI
`149
`The FDDI FrameStructure
`Summary of FDDI Characteristics
`
`149
`
`150
`AppleTalk
`150
`AppleTalk Specifications
`150
`How AppleTalk Works
`151
`Advantages of AppleTalk
`Disadvantages of AppleTalk
`151
`LocalTalk Data Transmission
`151
`Summary of AppleTalk Characteristics
`
`151
`
`151
`ARCnet
`151
`How ARCnet Works
`152
`ARCnetSpecifications
`153
`Advantages of ARCnet
`153
`Disadvantages of ARCnet
`153
`The ARCnetPacket Structure
`Summary of ARCnet Characteristics
`
`153
`
`006
`
`006
`
`
`
`
`
`xiii
`
`Comparing Networking Architectures
`
`154
`
`Summary
`
`154
`
`Further Reading
`
`155
`
`Review Questions
`
`155
`
`Chapter 6
`
`WANLinks
`
`159
`
`160
`
`WANHardware
`Modems
`160
`165
`ISDN and DSL Adapters
`Customer Premises Equipment
`WANTopologies
`166
`The Point-to-Point WAN 166
`The WAN Ring
`167
`The WANStar
`168
`Multitiered WANs
`
`169
`
`165
`
`170
`176
`
`178
`
`170
`Network Switching Types
`Circuit-Switching Networks
`Packet-Switching Networks
`
`Emerging WAN Technologies
`OC-SONET 179°
`Broadband ISDN 179
`CATV 179
`SMDS
`181
`Wireless WAN 181
`
`LAN/WANConnectivity 182
`Translated Connections
`182
`Proxy Servers
`185
`Routed Connections
`
`186
`
`Summary
`
`187
`
`Further Reading
`
`188
`
`Review Questions
`
`188
`
`Part Il
`Chapter 7
`
`Networking Hardware and Software
`Physical Components of the Network
`
`193
`195
`
`i
`
`195
`NICs
`The Role of the NIC in Network Communications
`Selectinga NIC 196
`
`195
`
`007
`
`
`
`007
`
`
`
`xiv
`
`Configuring and Using a NIC 197
`
`200
`Network Media
`200
`Cable Types
`Wireless Media
`207
`
`Network Connectivity Devices
`Simple Connectors
`211
`Complex Connectors
`213
`Segmenting and Subnetting Devices
`
`210
`
`214
`
`Summary
`
`222
`
`Further Reading
`
`222
`
`Review Questions
`
`222
`
`Chapter 8
`
`Networking Protocols and Services
`
`227
`
`227
`
`NetBIOS/NetBEUI
`IPX/SPX 229
`The Network Layer Protocol: IPX 229
`The Transport Layer Protocol: SPX 230
`
`TCP/IP 231
`231
`The TCP/IP Suite
`The Network Layer Protocol: IP 231
`The Transport Layer Protocols: TCP and UDP 245
`Addressing the Envelope: Packet Headers
`248
`Name Resolution
`249
`TCP/IP Utilities
`254
`Application Layer Protocols
`
`261
`
`Summary
`
`262
`
`Further Reading
`
`262
`
`Review Questions
`
`263
`
`Chapter9
`
`The Widest Area Network: The Global Internet 267 |
`
`The Evolution of the Internet
`267
`The Development of the Backbone
`The Internet2 Project
`269
`
`268
`
`269
`The Components of the Internet
`The Local Computer or LAN 270
`The ISP 270
`The Regional Network 270
`NAPs
`271
`
`008
`
`008
`
`
`
`XV
`
`
`272
`
`271
`MAEs
`HowInternet Components Work Together
`Whatthe Internet Does
`273
`The World Wide Web
`274
`E-mail and Mailing Lists
`283
`Newsgroups
`287
`File Transfer
`289
`Telnet
`290
`Streaming Media
`Live Chat
`291
`Audio/Videoconferencing
`Internet Telephony
`292
`Virtual Private Networking
`
`292
`
`293
`
`291
`
`293
`
`TCP/IP Routing and the Internet
`How IP Routing Works
`294
`An Exampleof a Simple Routed Network
`Types of Routing Interfaces 296
`296
`Static Versus Dynamic Routing
`Distance-Vector Versus Link-State Protocols
`Common Routing Protocols
`299
`
`294
`
`298
`
`301
`
`Who Ownsthe Internet?
`ISOC 302
`TAB 302
`IETF 302
`IESG 302
`IANA/ICANN 302
`W3C 302
`
`Summary
`
`303
`
`Further Reading
`
`303
`
`Chapter10
`
`Review Questions
`304
`— Network Operating Systems 307
`General Network Administration
`307
`The Client/Server Environment
`309
`Sharing Network Resources
`311
`
`320
`Overview of NOSs
`Windows NT and Windows 2000 Networks
`NetWare Networks
`326
`UNIX and Linux Networks
`Other NOSs
`334
`
`329
`
`320
`
`009
`
`
`
`009
`
`
`
`xvi
`
`Summary
`
`335
`
`Further Reading
`
`336
`
`Review Questions
`
`336
`
`Chapter 11
`
`Directory Services
`
`341
`
`WhatAre Directories and Directory Services?
`What Isa Directory?
`341
`WhatAre Directory Services?
`
`343
`
`34]
`
`Directory Services Standards
`X.500
`346
`DAP and LDAP 347
`
`346
`
`Directory-Enabled Networking
`
`349
`
`Popular Directory Services
`Novell NDS
`349
`Microsoft Active Directory
`Other Directory Services
`
`349
`
`350
`354
`
`Summary
`
`356
`
`Further Reading
`
`357
`
`Review Questions
`
`357
`
`Chapter 12
`
`Desktop Operating Systems
`
`361
`
`361
`Operating System Basics
`Operating System Interfaces
`Using Commands
`364
`Files and File Systems
`
`367
`
`362
`
`Common Desktop Operating Systems
`MS-DOS and Windows 3.x
`379
`Windows 9x
`381
`Windows NT Workstation
`Windows 2000 Professional
`Linux/UNIX 396
`Macintosh
`401
`OS/2
`403
`
`388
`392
`
`379
`
`Summary
`
`404
`
`Further Reading
`
`404
`
`Review Questions
`
`405
`
`010
`
`010
`
`
`
`xvii
`
`
`Chapter 13
`
`Hybrid Networks 409
`
`409
`Characteristics of the Hybrid Network
`Inability of a Single Vendor to Provide All Desired Features
`Personal Preferences of Users
`410
`Budgetary Factors
`410
`Haphazard Growth
`411
`
`410
`
`411
`Multiple-Protocol Networks
`Network/Transport Protocols
`411
`File-Sharing Protocols
`415
`
`415
`Multiple-Operating-System Networks
`415
`Multiple Server Operating Systems
`417
`Multiple Client Operating Systems
`Multiple Server and Multiple Client Operating Systems
`Multiple-Platform Networks
`417
`418
`PC-to-Macintosh Communications
`418
`PC-to-Mainframe Communications
`PDA-to-PC and Handheld-to-PC Communications
`
`419
`
`417
`
`Gateway: The Hybrid Connectivity Solution
`Windows-to-NetWare Redirectors
`420
`Cross-Platform Solutions
`420
`SNA 421
`Samba
`422
`
`419
`
`Summary
`
`424
`
`Further Reading
`
`425
`
`Review Questions
`
`425
`
`Part Ill
`Chapter 14
`
`Network Specialty Areas 429
`Protecting the Network
`431
`
`431
`Network Security
`432
`Assessing Security Needs
`434
`Assessing Security Threats
`441
`Implementing Security Measures
`How Security Components Work 448
`Advanced Identification and Authentication Technologies
`Developing Security Policies
`457
`
`454
`
`Disaster Protection and Recovery
`Power Backup
`465
`Data Backup
`466
`
`465
`
`011
`
`011
`
`
`
`xvili
`
`
`Disk Fault Tolerance 469
`Clustering Technologies
`47]
`
`Summary 471
`
`Further Reading
`
`472
`
`Review Questions
`
`473
`
`Chapter 15
`
`Remote Access 477
`
`478
`
`Why Remote Access?
`Branch Offices
`478
`After-Hours Connectivity 478
`Telecommuting 479
`Mobile Users
`480
`Providing Access to Clients and Partners
`
`480
`
`483
`
`481
`How Remote Access Works
`Protocols Used for Remote Access
`Remote Access Authentication 482
`Assignment of IP Addresses
`483
`Aggregation of Bandwidth on Dialup Connections
`Control of Bandwidth Usage 484
`Remote Access Connectivity Devices
`Modems
`484
`ISDN Terminal Adapters
`Cable Modems
`493
`CSU/DSUs
`494
`
`482
`
`484
`
`492
`
`Configuring Remote Access Clients and Servers
`Configuring a Remote Access Client
`495
`Configuring a Remote Access Server
`496
`
`495
`
`Remote Access Security Issues 496
`Callback Security 497
`RADIUS 498
`Remote Access Policies
`Account Lockout
`499
`Security Hosts
`499
`
`498
`
`Summary 499
`
`Further Reading
`
`500
`
`Review Questions
`
`501
`
`012
`
`012
`
`
`
`xix
`
`
`Chapter 16
`
`Virtual Private Networking 505
`What Isa VPN?
`505
`Virtual Networking
`Private Networking
`
`505
`506
`
`506
`How VPNs Work
`Digging the Tunnel
`507
`Operating System Support for VPNs
`509
`WhyUseVirtual Private Networking?
`510
`VPN Versus Dialup Networking: Advantages and Disadvantages
`
`VPN Scenarios
`
`512
`
`510
`
`516
`VPN Protocols
`Tunneling Protocols
`Encryption Protocols
`LAN Protocols
`520
`
`516
`519
`
`520
`VPN Security
`521
`Authentication
`521
`Authorization
`Encryption
`521
`
`VPN Performance Issues . 521
`
`522
`Types of VPNs
`Software-Based VPNs
`Hardware-Based VPNs
`
`522
`522
`
`Configuring a VPN Connection
`Summary
`525
`
`522
`.
`
`Further Reading
`
`526
`
`526
`Review Questions
`531
`Thin Client Networking
`Chapter 17
`The Evolution of Thin Client Networking_532
`Thin Client Technology
`533
`Advantages of Thin Client Technology
`Thin Client Protocols
`535
`RDP 536
`ICA 536
`
`534
`
`X and X Display Manager Communication Protocol (XDMCP)
`
`RFB 537
`BOOTP, DHCP, and TFTP 537
`
`536
`
`013
`
`013
`
`
`
`XX
`
`
`538
`
`Thin Client Hardware
`WBTs
`539
`Network Computers
`Net PCs
`540
`540
`Desktop Computers
`The Thinnest Clients: Handheld PCs
`
`539
`
`540
`
`541
`Thin Client Software
`Microsoft Terminal Services
`Citrix Winframe/MetaFrame
`The X Window System 543
`Web-Based Computing
`544
`The JVM 544
`
`541
`542
`
`545
`ASPs
`Microsoft .NET 545
`
`Summary
`
`546
`
`Chapter 18
`
`546
`Further Reading
`Review Questions 547
`Monitoring, Management, and Troubleshooting Tools
`Analyzing and Optimizing Network Performance
`551
`Bottlenecks
`552
`Baselines
`553
`554
`Best Practices
`Determining Internet Connection Speed
`
`554
`
`551
`
`Network Monitoring and Management Tools
`Networking Monitoring Software
`556
`Network ManagementSoftware
`562
`ManagementSoftware for Small and Medium-Sized Networks
`ManagementService Providers
`568
`
`556
`
`567
`
`Hardware Monitoring and Troubleshooting Devices
`Troubleshooting Network Problems
`569
`Troubleshooting Basics
`569
`Using Operating System Log Files
`Using TCP/IP Utilities
`573
`Problem-Solving Guidelines
`
`579
`
`571
`
`568
`
`Summary
`
`580
`
`Further Reading
`
`581
`
`Review Questions
`
`581
`
`014
`
`014
`
`
`
`xxi
`
`
`Part IV
`Chapter 19
`
`The Future of Networking 585
`Tomorrow’s Technologies
`587
`
`587
`Ubiquitous Computing
`588
`Bringing Networking Home
`Overcoming the Limits of IP 589
`New Directions in Networking Technologies
`Universal Connectivity
`592
`"Smart” Everything
`593
`Networking the Family
`594
`That’s Entertainment
`594
`Privacy Issues: Big Brother Is Watching
`Networking at Work
`595
`The Impact of Networking Technologies on Government
`The Impact of Networking Technologies on Law 598
`The Impact of Networking Technologies on Medicine
`The Impact of Networking Technologies on Publishing
`New Waysof Learning
`601
`
`590
`
`594
`
`596
`
`599
`600
`
`602
`Artificial Intelligence
`Computers That Think
`602
`Cybernetic Life-Forms: The Ultimate Network
`
`603
`
`Summary
`
`603
`
`Further Reading
`
`604
`
`Parting Questions
`604
`Chapter Review Answer Key 607
`
`Appendix A
`Glossary 635
`
`Index 695
`
`015
`
`015
`
`
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