Warning and Disclaimer This book is designed to provide information about CCNA 1: Networking Basics and CCNA 2: Routers and Routing Basics of the Cisco Networking Academy Program CCNA co
Trang 1Cisco Networking Academy Program
CCNA 1 and 2 Companion Guide
Third Edition
Cisco Systems, Inc
Cisco Networking Academy Program
Cisco Press
201 West 103rd StreetIndianapolis, Indiana 46290 USA
www.ciscopress.com
1102.book Page i Tuesday, May 20, 2003 2:53 PM
Trang 2Cisco Networking Academy Program
CCNA 1 and 2 Companion Guide
Third Edition
Cisco Systems, Inc.
Cisco Networking Academy Program Copyright © 2003 Cisco Systems, Inc.
Published by:
Cisco Press
201 West 103rd Street Indianapolis, IN 46290 USA All rights reserved No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without written permission from the publisher, except for the inclu- sion of brief quotations in a review.
Printed in the United States of America 1 2 3 4 5 6 7 8 9 0 Library of Congress Cataloging-in-Publication Number: 2002116787 ISBN: 1-58713-110-2
First Printing June 2003
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All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized Cisco Press or Cisco Systems, Inc., cannot attest to the accuracy of this information Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark.
Warning and Disclaimer
This book is designed to provide information about CCNA 1: Networking Basics and CCNA 2: Routers and Routing Basics of the Cisco Networking Academy Program CCNA course Every effort has been made to make this book as complete and as accurate as possible, but no war- ranty or fitness is implied.
The information is provided on an “as is” basis The author, Cisco Press, and Cisco Systems, Inc., shall have neither liability nor responsibility to any person or entity with respect to any loss
or damages arising from the information contained in this book or from the use of the discs or programs that may accompany it.
The opinions expressed in this book belong to the author and are not necessarily those of Cisco Systems, Inc.
This book is part of the Cisco Networking Academy Program series from Cisco Press The products in this series support and complement the Cisco Networking Academy Program curriculum If you are using this book outside the Networking Academy program, then you are not preparing with a Cisco trained and authorized Networking Academy provider.
For information on the Cisco Networking Academy Program or to locate a Networking Academy,
®
Trang 3iii
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1102.book Page iii Tuesday, May 20, 2003 2:53 PM
Trang 4Cisco Representative Anthony Wolfenden Cisco Press Program Manager Sonia Torres Chavez Manager, Marketing Communications, Scott Miller Cisco Systems
Cisco Marketing Program Manager Edie Quiroz Production Manager Patrick Kanouse Senior Development Editor Chris Cleveland
Copy Editors Krista Hansing, Kevin A Kent, Gayle Johnson Technical Editors Jhun DeLeon, Ralph Duffy, Jim Lorenz, Arthur Tucker
Trang 5v
Overview Foreword xxv
Introduction xxvii
Part I CCNA 1: Networking Basics 3
Chapter 1 Introduction to Networking 5
Chapter 2 Networking Fundamentals 43
Chapter 3 Networking Media 115
Chapter 4 Cable Testing and Cabling LANs and WANs 183
Chapter 5 Ethernet Fundamentals 251
Chapter 6 Ethernet Technologies and Ethernet Switching 315
Chapter 7 TCP/IP Protocol Suite and IP Addressing 375
Chapter 8 Routing Fundamentals and Subnets 427
Chapter 9 TCP/IP Transport and Application Layer 477
Part II CCNA 2: Routers and Routing Basics 509
Chapter 10 WANs and Routers 511
Chapter 11 Router Fundamentals 553
Chapter 12 Router Configuration 587
Chapter 13 Learning About Neighboring and Remote Devices 621
Chapter 14 Managing Cisco IOS Software 645
Chapter 15 Routing and Routing Protocols 675
Chapter 16 Distance Vector Routing Protocols 711
Chapter 17 TCP/IP Error and Control Messages 761
1102.book Page v Tuesday, May 20, 2003 2:53 PM
Trang 6Chapter 18 Basic Router Troubleshooting 787
Chapter 19 Intermediate TCP 815
Chapter 20 Access Control Lists 841
Part III Appendixes 877
Appendix A Structured Cabling 879
Appendix B Glossary of Key Terms 979
Appendix C Check Your Understanding Answer Key .1009
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Table of Contents Foreword xxv Introduction xxvii Part I CCNA 1: Networking Basics 3
Chapter 1 Introduction to Networking 5
The Fundamentals of Internet Connectivity 5
PC Basics 6
Electronic Components 7
PC Components 7
Motherboard Components 10
Desktop Versus Laptop 11
Network Interface Cards 12
NIC and Modem Installation 13
Overview of High-Speed and Dialup Connectivity 14
TCP/IP Configuration 15
Testing Connectivity with Ping 15
Web Browsers and Plug-Ins 16
Other Common Computer Applications 18
Binary Numbers 18
Binary Representation of Data 19
Bits, Bytes, and Measurement Terms 19
Base 10 Number System 21
Base 2 Number System 22
Base 16 Number System 23
Decimal-to-Binary Conversion 24
Binary-to-Decimal Conversion 26
Hexadecimal and Binary Conversion 28
Four-Octet Dotted-Decimal Representation of a 32-Bit Binary Number 30
Boolean Logic 30
IP Addresses and Subnet Masks 32
Summary 33
Key Terms 35
Check Your Understanding 39 1102.book Page vii Tuesday, May 20, 2003 2:53 PM
Trang 8Chapter 2 Networking Fundamentals .43
Networking Terminology 43
Data Networks .44
Computer Networking History 47
Network Protocols 49
Local-Area Networks (LANs) 49
Wide-Area Networks (WANs) 50
Metropolitan-Area Networks (MANs) .52
Specialized Networks Located Within the LAN 53
Virtual Private Networks 56
Digital Bandwidth 58
The Importance of Bandwidth 58
Analogies That Describe Digital Bandwidth 59
Digital Bandwidth Measurements 61
Bandwidth Limitations .61
Data Throughput 63
Data Transfer Calculation 64
Digital Bandwidth Versus Analog Bandwidth .66
Networking Models 67
Using Layers to Analyze Problems in a Flow of Materials 67
Using Layers to Describe Data Communication 68
The OSI Reference Model 69
OSI Layers and Functions 71
Peer-to-Peer Communications 72
DoD (TCP/IP) Model 74
Detailed Encapsulation Process 75
Networking Devices 78
Repeaters 79
Hubs 79
Network Interface Cards 81
Bridges 82
Layer 2 Switches 83
Routers 84
Voice, DSL, Cable Modem, and Optical Devices 86
Security Devices 89
Wireless Devices 91
Network Topologies 93
Bus Topology 95
Star and Extended-Star Topologies .95
Ring Topology 97
Trang 9ix
Hierarchical Topology 98
Full-Mesh and Partial-Mesh Topologies 98
Logical Topology 99
Summary 100
Key Terms 103
Check Your Understanding 106
Chapter 3 Networking Media 115
Electricity Basics 115
Atoms and Molecules 115
Electrical Properties of Matter 117
Measuring Electricity 118
Voltage 119
Current 120
Wattage 120
Resistance and Impedance 120
Circuits 121
Copper Media 123
American Wire Gauge System 123
Twisted-Pair Cable 124
Shielded Twisted-Pair Cable 124
Unshielded Twisted-Pair Cable 125
Coaxial Cable 128
Cable Specification and Termination 130
Optical Media 133
The Electromagnetic Spectrum 134
The Ray Model of Light 135
The Law of Reflection 137
The Law of Refraction (Snell’s Law) 138
Total Internal Reflection 139
Fiber-Optic Cables 141
Multimode Fiber 144
Single-Mode Fiber 145
Cable Designs 146
Other Optical Networking Components 147
Signals and Noise in Optical Fiber 149
Installation, Care, and Testing of Optical Fiber 151
Wireless Communications 154
Wireless Data Communications 154 1102.book Page ix Tuesday, May 20, 2003 2:53 PM
Trang 10Wireless Signal 155
Radio Frequency Bands 157
Spread-Spectrum Technology 159
FHSS Versus DSSS 159
Wireless Networking 161
Wireless LAN Organization and Standards 161
Wireless Devices and Topologies 162
How Wireless LANs Communicate 165
Authentication and Association 166
The Radio Wave/Microwave Spectrum .168
Signals and Noise on a WLAN .169
Wireless Security 170
WEP .170
VPN, EAP, and LEAP 171
Summary 172
Key Terms 174
Check Your Understanding 176
Chapter 4 Cable Testing and Cabling LANs and WANs 183
Background for Studying Frequency-Based Cable Testing 184
Waves .184
Sine Waves and Square Waves 185
Exponents and Logarithms .186
Decibels 187
Viewing Signals in Time and Frequency .188
Noise in Time and Frequency 189
Analog and Digital Bandwidth 190
Signals and Noise on Networking Media 191
Signaling over Copper and Fiber-Optic Cabling 192
Attenuation and Insertion Loss on Copper Media 195
Source of Noise on Copper Media 196
Cable Testing Standards 199
Other Test Parameters 202
Time-Based Parameters 202
Testing Fiber-Optic Cables 203
A New Cabling Standard 204
Cabling the LANs 205
LAN Physical Layer 205
Trang 11xi
Ethernet in the Campus 206
Ethernet Media and Connector Requirement 208
Connection Media 210
UTP Implementation 212
LAN Connection Devices 216
Repeaters 216
Hubs 217
Bridges 218
Switches 221
Wireless Networking Media 222
Host LAN Connectivity: NICs and Interfaces 225
Workstation and Server Relationships 226
Peer-to-Peer Networks 227
Client/Server Networks 228
Cabling the WAN 231
WAN Physical Layer 232
WAN Serial Connections 232
Routers and Serial Connections 234
Routers and ISDN BRI Connections 236
Routers and DSL Connections 238
Routers and Cable Connections 239
Setting Up Console Connections 240
Summary 242
Key Terms 244
Check Your Understanding 247
Chapter 5 Ethernet Fundamentals 251
History and Evolution of Ethernet 251
Introduction to Ethernet 252
IEEE Ethernet Naming Rules 253
IEEE 802.3/Ethernet and the OSI Model 255
MAC Addressing 258
Framing in General 259
Ethernet Frame Structure 262
Ethernet Frame Fields 264
Ethernet Operation 266
Media Access Control 266
Ethernet MAC 268
Simplex, Half-Duplex, and Full-Duplex Operation 271 1102.book Page xi Tuesday, May 20, 2003 2:53 PM
Trang 12Ethernet Timing 272
Interframe Spacing and Backoff 275
Error Handling .277
Types of Collisions 279
Ethernet Errors .282
Ethernet Autonegotiation 285
Link Establishment and Full/Half Duplex 288
Collision Domains and Broadcast Domains .290
Directly Connected Networks 290
Indirectly Connected Networks 291
Collisions and Collision Domains 292
Segmentation 295
Layer 2 Broadcasts 297
Broadcast Domains 300
Introduction to Data Flow 300
Network Segment .302
Summary 304
Key Terms 306
Check Your Understanding 309
Chapter 6 Ethernet Technologies and Ethernet Switching 315
10-Mbps and 100-Mbps Ethernet 315
10-Mbps Versions of Ethernet 316
10BASE5 320
10BASE2 321
10BASE-T 322
10BASE-T Architecture 326
100BASE-TX 329
100BASE-FX 332
Fast Ethernet Architecture 334
Gigabit, 10-Gb, and Future Ethernet 337
1000-Mbps Versions of Ethernet (Gigabit) 337
1000BASE-T 339
1000BASE-SX and 1000BASE-LX 342
Gigabit Ethernet Architecture .345
10-Gbps Versions of Ethernet .347
10GbE Media, Connections, and Architecture 350
The Future of Ethernet 354
Ethernet Switching 355
Trang 13xiii
Layer 2 Bridging 356
Layer 2 Switching 357
Microsegmentation 359
Full-Duplex Transmission 360
Latency 360
Switch Modes 361
Introduction to the Spanning Tree Protocol 362
Summary 366
Key Terms 368
Check Your Understanding 370
Chapter 7 TCP/IP Protocol Suite and IP Addressing 375
Introduction to TCP/IP 375
Application Layer 377
Transport Layer 378
Internet Layer 380
Network Access Layer 381
Comparing the OSI Reference Model Layers and the TCP/IP Reference Model Layers 382
Internet Architecture 383
IP Addresses 386
32-Bit Dotted-Decimal IP Address 386
Decimal and Binary Conversion 389
IPv4 Addressing 392
IP Address Classes 394
Reserved IP Addresses 398
Public and Private Addresses 400
Introduction to Subnetting 402
IPv4 Versus IPv6 404
IP Address Assignment, Acquisition, and Hierarchy 407
Obtaining an Internet Address 407
Static Assignment of an IP Address 408
Address Resolution Protocol 408
RARP IP Address Assignment 412
Bootstrap Protocol (BOOTP) IP Address Assignment 414
Dynamic Host Configuration Protocol (DHCP) IP Address Assignment 415
Problems in Address Resolution 417
Summary 419 1102.book Page xiii Tuesday, May 20, 2003 2:53 PM
Trang 14Key Terms 421
Review Questions 422
Chapter 8 Routing Fundamentals and Subnets .427
Routed, Routable, and Routing Protocols 427
Routing Overview 430
Routing Versus Switching .432
Routed Versus Routing 435
Path Determination 437
Routing Tables 440
Routing Algorithms and Metrics 441
Interior and Exterior Routing Protocols 443
Routing Protocols 444
IP as a Routed Protocol 448
Packet Propagation and Switching Within a Router 449
Connectionless Versus Connection-Oriented Network Services 451
Anatomy of an IP Packet 453
The Mechanics of Subnetting 455
Introduction to and Reasons for Subnetting 455
Establishing the Subnet Mask Address 458
Creating a Subnet .460
Calculating the Resident Subnetwork Through ANDing 463
Summary 465
Key Terms 467
Check Your Understanding 470
Chapter 9 TCP/IP Transport and Application Layer 477
Understanding the TCP/IP Transport Layer 478
Flow Control 479
Session Establishment, Maintenance, and Termination Overview 480
Three-Way Handshake 482
Windowing 483
Acknowledgment 484
TCP 486
UDP 487
TCP and UDP Port Numbers 488
TCP/IP Application Layer 491
Trang 15xv
Introduction to the Application Layer 491
DNS 494
FTP and TFTP 495
HTTP 496
SMTP 497
SNMP 498
Telnet 499
Summary 500
Key Terms 501
Check Your Understanding 502
Part II CCNA 2: Routers and Routing Basics 509
Chapter 10 WANs and Routers 511
WAN Characteristics 511
WAN Devices 515
WAN Standards 515
WAN Connection Options 519
WAN Routers 529
Router Internal Components 529
Router External Connections 535
Management Port Connections 535
The Function of a Router in a WAN 536
Lab WAN Simulation 541
Summary 544
Key Terms 545
Check Your Understanding 546
Chapter 11 Router Fundamentals 553
Router Boot Sequence and Setup Mode 553
Router Startup Sequence 554
System Configuration Dialog 555
Setting Up Global Parameters 556
Router LED Indicators 559
Initial Router Boot-Up Output 560
Establishing a HyperTerminal Session 562
Logging into the Router 565
Keyboard Help 566
Router Help Functions 569 1102.book Page xv Tuesday, May 20, 2003 2:53 PM
Trang 16Cisco IOS Software Editing Commands 571
Router Command History .572
Cisco IOS Software Fundamentals .574
Operation of Cisco IOS Software 574
Cisco IOS Software Features 575
The show version Command 577
Router User Interface 577
Router User Interface and Modes .578
Troubleshooting Cisco IOS Software 579
Summary 581
Key Terms 582
Check Your Understanding 582
Chapter 12 Router Configuration 587
Command-Line Interface Command Modes 587
User Command List 587
Privileged Mode Command List 589
Router Configuration Modes 592
Router Startup Modes 594
Configuring a Router Name 595
Configuring and Protecting Router Passwords .596
Examining the show Commands 597
Configuring a Serial Interface 600
Configuring an Ethernet Interface 601
Executing Changes to the Router 602
Finishing the Configuration 603
Importance of Configuration Standards 603
Providing Interface Descriptions .604
Configuring Interface Descriptions 604
Login Banners 605
Configuring a Message of the Day 606
Host Name Resolution .606
Configuration Backup and Documentation 607
Password Recovery 609
Overview of Password Recovery 609
Password Recovery Technique 1 .610
Password Recovery Technique 2 .611
Trang 17xvii
Summary 614
Key Terms 615
Check Your Understanding 615
Chapter 13 Learning About Neighboring and Remote Devices 621
Introduction to CDP 621
Obtaining Information with CDP 622
Showing CDP Neighbors 623
Implementating, Monitoring, and Maintaining CDP Information 625
Creating a Network Map of the Environment 627
Disabling and Troubleshooting CDP 627
Getting Information About Remote Devices 629
Telnet 629
Alternative Connectivity Tests 632
Summary 640
Key Terms 641
Check Your Understanding 641
Chapter 14 Managing Cisco IOS Software 645
Stages of the Router Power-On/Boot Sequence 645
Locating and Loading Cisco IOS Software 646
Using the boot system Command 647
Configuration Register Values 649
Displaying the Currently Running Cisco IOS Software Version 650
Managing Cisco IOS Software Images 651
Cisco IOS Software Naming Conventions 654
Managing Configuration File Using TFTP 656
Managing Configuration Files with HyperTerminal 658
Managing Cisco IOS Software Images with TFTP 660
Managing Cisco IOS Software Images with ROMmon 662
Verifying the File System 667
Summary 669
Key Terms 670
Check Your Understanding 670 1102.book Page xvii Tuesday, May 20, 2003 2:53 PM
Trang 18Chapter 15 Routing and Routing Protocols 675
Routing Basics .675
How Routers Route Packets from Source to Destination 676
Network and Host Addressing 677
Path Selection and Packet Switching .678
Routed Protocols Versus Routing Protocols 678
Network Layer Protocol Operations 679
Multiprotocol Routing 680
Static Routing 681
Static Versus Dynamic Routes 681
The Purpose of a Static Route 681
Static Route Operation .681
Configuring Static Routes .684
How a Default Route Is Used .687
Configuring Default Route Forwarding 687
Verifying Static Route Configuration 689
Troubleshooting Static Route Configuration 689
Dynamic Routing Overview 690
Routing Protocol Examples 691
Purpose of a Routing Protocol and Autonomous Systems 692
Dynamic Routing Operations .693
How Distances on Network Paths Are Determined by Various Metrics 693
Identifying the Classes of Routing Protocols 694
Distance Vector Routing Protocol Features 695
Link-State Routing Basics .697
Hybrid Routing Protocol Features 701
Configuring a Router to Use Routing Protocols .701
Autonomous Systems and IGP vs EGP 703
Summary 704
Key Terms 705
Check Your Understanding 706
Chapter 16 Distance Vector Routing Protocols 711
Initial Router Configuration 711
Distance Vector Routing 712
Maintaining Routing Information Through Distance Vector Protocols 712
Trang 19xix
Load Balancing Across Multiple Paths 713
How Routing Loops Occur in Distance Vector 714
Defining a Maximum to Prevent Count to Infinity 715
Eliminating Routing Loops Through Split Horizon 716
Route Poisoning 717
Avoiding Routing Loops with Triggered Updates 718
Preventing Routing Loops with Hold-Down Timers 719
Preventing Routing Updates Through an Interface 720
Examining the Routing Table 721
The show ip route Command 721
Determining the Gateway of Last Resort 722
Determining Route Source to Route Destination 723
Determining Layer 2 and Layer 3 Addresses from the Source to the Destination 723
Determining Route Administrative Distance 724
Determining Route Metric 725
Determining Route Next Hop 726
Determining Last Route Updates 726
Observing Multiple Paths to Destination 729
RIP Features 729
Enabling RIP on an IP Network 730
Using the ip classless Command 731
Common RIP Configuration Issues 732
Verifying RIP Configuration 735
Troubleshooting RIP 738
Load Balancing with RIP 740
Integrating Static Routes with RIP 741
IGRP 744
IGRP Features 744
IGRP Metrics 745
Interior, System, and Exterior IGRP Routes 746
IGRP Stability Features 747
Configuring IGRP 748
Verifying the IGRP Configuration 749
Troubleshooting IGRP 751
Summary 754
Key Terms 755
Check Your Understanding 756 1102.book Page xix Tuesday, May 20, 2003 2:53 PM
Trang 20Chapter 17 TCP/IP Error and Control Messages 761
Functionality and Role of IP in Error Control 761
ICMP 762
ICMP Message Delivery 762
Error Reporting and Error Correction 763
Unreachable Networks .764
Using ping to Test Destination Reachability 765
Detecting Excessively Long Routes .769
ICMP Message Format: Echo Messages 769
ICMP Message Format: Destination Unreachable Message 771 Miscellaneous Error Reporting .773
TCP/IP Suite Control Messages 773
ICMP Redirect/Change Requests 773
Clock Synchronization and Transit Time Estimation 775
Information Requests and Reply Message Formats 776
Address Mask Requests 777
Router-Discovery Message 778
Router-Solicitation Message 780
Congestion and Flow-Control Messages 780
Summary 781
Key Terms 782
Check Your Understanding 782
Chapter 18 Basic Router Troubleshooting 787
Introduction to Network Testing 787
Structured Approach to Troubleshooting 788
Testing by OSI Layers .790
Troubleshooting Layer 1 Using Indicators 791
Troubleshooting Layer 2 Using the show interface Command 792
Troubleshooting Layer 3 Using ping .793
Troubleshooting Layer 3 Issues Using traceroute 795
Troubleshooting Layer 7 Using Telnet 797
Troubleshooting Router Issues Using the show interface and show interfaces Commands 798
Troubleshooting Routing Issues Using the show cdp neighbors Command 801
Troubleshooting Routing Issues Using show ip route and show ip protocol 803
Trang 21xxi
Troubleshooting Router Connections Using the show controllers serial Command 805
Introduction to debug 806
Summary 809
Key Terms 810
Check Your Understanding 810
Chapter 19 Intermediate TCP 815
The TCP/IP Protocol Suite 815
TCP/IP Protocol Stack and the Application Layer 816
TCP/IP Protocol Stack and the Transport Layer 818
TCP and UDP Segment Format 819
TCP Operation 820
Three-Way Handshake 821
Denial-of-Service Attacks During Synchronization 822
Windowing and Window Size 823
Sequencing Numbers 825
Positive ACK 826
UDP Operation 827
Overview of Transport Layer Ports 828
Multiple Conversations Between Hosts 828
Ports for Services 831
Ports for Clients 832
Port Numbering and Well-Known Ports 832
Example of Multiple Sessions Between Hosts 832
Comparison of MAC Addresses, IP Addresses, and Port Numbers 833
TCP/IP and the Internet Layer 833
How ARP Works 834
Summary 835
Key Terms 836
Check Your Understanding 836
Chapter 20 Access Control Lists 841
ACL Overview 841
Why Create ACLs? 843
Creating an ACL: Why Order Matters 844
Using ACLs 844 1102.book Page xxi Tuesday, May 20, 2003 2:53 PM
Trang 22How ACLs Work .845ACL Configuration Tasks 847Assigning a Unique Number to Each ACL .847Using Wildcard Mask Bits 848Using the Wildcard any 850Using the Wildcard host 851Standard ACLs 852Extended ACLs 855Configuring Extended ACLs for ICMP .861Configuring Extended ACLs for IGMP 861Configuring Extended ACLs for TCP 861Configuring Extended ACLs for UDP .862Extended ACL Defaults 862Named ACLs .863Placing ACLs .866Firewalls 867Using ACLs with Firewalls 868Restricting Virtual Terminal Access 869Verifying ACLs 870Summary 871Key Terms 872Check Your Understanding 872
Part III Appendixes 877 Appendix A Structured Cabling 879
Mounting Jacks in Drywall 928Mounting Jacks in Plaster 929Mounting Jacks in Wood 930Flush-Mounting a Jack in a Wall 930Pulling Cable to the Jacks .930Fishing Cable from Below a Wall 931
Appendix B Glossary of Key Terms 979
Appendix C Check Your Understanding Answer Key .1009
Trang 23xxiii
Cisco Systems Networking Icon Legend
Cisco Systems, Inc., uses a standardized set of icons to represent devices in network topology illustrations The following icon legend shows the most commonly used icons that you might encounter throughout this book
DSU/CSU Router Bridge Hub DSU/CSU
Catalyst Switch
Multilayer Switch
ATM Switch
ISDN/Frame Relay Switch
Communication Server
Gateway Access
Server
PC with Software
Workstation
Macintosh Terminal
File Server
Web Server
Cisco Works Workstation
Printer Laptop
Front End Processor
Cluster Controller
Modem
Network Cloud
Token Ring
1102.book Page xxiii Tuesday, May 20, 2003 2:53 PM
Trang 24Command Syntax Conventions
The conventions used to present command syntax in this book are the same tions used in the Cisco IOS Software Command Reference The Command Reference describes these conventions as follows:
conven-■ Vertical bars (|) separate alternative, mutually exclusive elements
■ Square brackets ([ ]) indicate optional elements
■ Braces ({ }) indicate a required choice
■ Braces within brackets ([{ }]) indicate a required choice within an optional element
■ Boldface indicates commands and keywords that are entered exactly as shown.
■ Italic indicates arguments for which you supply values.
Trang 25xxv
Foreword
Throughout the world, the Internet has brought tremendous new opportunities for
individuals and their employers Companies and other organizations are seeing dramatic
increases in productivity by investing in robust networking capabilities Some studies
have shown measurable productivity improvements in entire economies The promise
of enhanced efficiency, profitability, and standard of living is real and growing
Such productivity gains aren’t achieved by simply purchasing networking equipment
Skilled professionals are needed to plan, design, install, deploy, configure, operate,
maintain, and troubleshoot today’s networks Network managers must assure that
they have planned for network security and for continued operation They need to
design for the required performance level in their organization They must implement
new capabilities as the demands of their organization, and its reliance on the network,
expands
To meet the many educational needs of the internetworking community, Cisco Systems
established the Cisco Networking Academy Program The Networking Academy is a
comprehensive learning program that provides students with the Internet technology
skills essential in a global economy The Networking Academy integrates face-to-face
teaching, web-based content, online assessment, student performance tracking, hands-on
labs, instructor training and support, and preparation for industry-standard certifications
The Networking Academy continually raises the bar on blended learning and educational
processes The Internet-based assessment and instructor support systems are some of
the most extensive and validated ever developed, including a 24/7 customer service
system for Networking Academy instructors Through community feedback and
elec-tronic assessment, the Networking Academy adapts the curriculum to improve outcomes
and student achievement The Cisco Global Learning Network infrastructure designed
for the Networking Academy delivers a rich, interactive, and personalized curriculum
to students worldwide The Internet has the power to change the way people work,
live, play, and learn, and the Cisco Networking Academy Program is in the forefront
of this transformation
This Cisco Press title is one of a series of best-selling companion titles for the Cisco
Networking Academy Program Designed by Cisco Worldwide Education and Cisco Press,
these books provide integrated support for the online learning content that is made
available to Academies all over the world These Cisco Press books are the only authorized
books for the Networking Academy by Cisco Systems, and provide print and CD-ROM
materials that ensure the greatest possible learning experience for Networking Academy
students
1102.book Page xxv Tuesday, May 20, 2003 2:53 PM
Trang 26I hope you are successful as you embark on your learning path with Cisco Systems and
the Internet I also hope that you will choose to continue your learning after you
com-plete the Networking Academy curriculum In addition to its Cisco Networking Academy
Program titles, Cisco Press also publishes an extensive list of networking technology
and certification publications that provide a wide range of resources Cisco Systems
has also established a network of professional training companies—the Cisco Learning
Partners—who provide a full range of Cisco training courses They offer training in
many formats, including e-learning, self-paced, and instructor-led classes Their instructors
are Cisco certified, and Cisco creates their materials When you are ready, please visit
the Learning & Events area on Cisco.com to learn about all the educational support
that Cisco and its partners have to offer
Thank you for choosing this book and the Cisco Networking Academy Program
Trang 27xxvii
Introduction
Cisco Networking Academy Program CCNA 1 and 2 Companion Guide, Third Edition,
supplements your classroom and laboratory experience with the Cisco Networking
Academy Program, whose curriculum is designed to empower you to enter employment
or further education and training in the computer networking field
This book trains you beyond the online materials that you already have used in this
program, and introduces you to topics pertaining to the Cisco Certified Network
Associate (CCNA) certification exam This book closely follows the style and format
that Cisco Systems has incorporated into the curriculum
This book introduces and extends your knowledge and practical experience with the
design, configuration, and maintenance of local-area networks (LANs) The concepts
covered in this book enable you to develop practical experience in skills related to
cabling, routing, IP addressing, routing protocols, and network troubleshooting This
book introduces the OSI model, discusses collisions and segmentations, and includes
a new chapter on Ethernet technologies and Ethernet switching This Companion
Guide also features greatly enhanced chapters on IOS and TCP/IP and an additional
chapter on access control lists
This book not only prepares you for the CCNA certification exam, but also for the
CompTIA Network+ certification exam
The Goal of This Book
The goal of this book is to educate you about Cisco supported networking technologies,
and to help you understand how to design and build networks and to configure Cisco
routers It is designed for use in conjunction with the Cisco Networking Academy Program
online curriculum
The Audience for This Book
This book’s main audience is students interested in networking technologies In
partic-ular, it is targeted toward students in the Cisco Networking Academy Program In the
classroom, this book can serve as a supplement to the online curriculum
This book is also appropriate for corporate training faculty and staff members, as well
as general users The book’s user-friendly, nontechnical approach is ideal for readers
who prefer to stay away from technical manuals
Trang 28Book Features
Many of this book’s features help facilitate a full understanding of the networking and routing covered in this book:
■ Objectives—Each chapter starts with a list of objectives that should be mastered
by the end of the chapter The objectives provide a reference of the concepts covered in the chapter
■ Figures, examples, tables, and scenarios—This book contains figures, examples,
and tables that help explain theories, concepts, commands, and setup sequences that reinforce concepts and help visualize the content covered in the chapter In addition, the specific scenarios provide real-life situations that detail the problem and the solution
■ Chapter summaries—At the end of each chapter is a summary of the concepts
covered in the chapter It provides a synopsis of the chapter and serves as a study aid
■ Key terms—Each chapter includes a list of defined key terms that are covered in
the chapter These terms serve as a study aid In addition, the key terms reinforce the concepts introduced in the chapter and help you understand the chapter material before you move on to new concepts You can find the key terms high-lighted in blue throughout the chapter where they are used in practice
■ Check Your Understanding questions—Review questions, presented at the end of
each chapter, serve as an assessment In addition, the questions reinforce the cepts introduced in the chapter and help test your understanding before you move on to new chapters
con-■ Lab Activity references—Throughout the book are references to worksheet and
lab activities found in Cisco Networking Academy Program CCNA 1 and 2 Lab
Companion, Third Edition These labs help you make a connection between
theory and practice
How This Book Is Organized
This book is divided into 20 chapters and 3 appendixes:
■ Chapter 1, “Introduction to Networking,” presents the basics of connecting to
the Internet It also introduces different number systems and the processes used
to convert a number from one number system to another This chapter sponds to the Module 1 content from the CCNA 1 online curriculum
Trang 29xxix
■ Chapter 2, “Networking Fundamentals,” introduces some of the terminology
used by networking professionals and various types of computer networks It also describes how the OSI reference model networking scheme supports net-working standards In addition, this chapter describes the basic functions that occur at each layer of the OSI model Finally, this chapter describes various network devices and networking topologies This chapter corresponds to the Module 2 content from the CCNA 1 online curriculum
■ Chapter 3, “Networking Media,” introduces the basic theory of electricity, which
provides a foundation for understanding networking at the physical layer of the OSI model This chapter also discusses different types of networking media that are used at the physical layer, including shielded twisted-pair cable, unshielded twisted-pair cable, coaxial cable, and fiber-optic cable, as well as wireless media
This chapter corresponds to the Module 3 content from the CCNA 1 online curriculum
■ Chapter 4, “Cable Testing and Cabling LANs and WANs,” describes issues
related to the testing of media used for physical layer connectivity in local-area networks (LANs) Networking media is literally and physically the backbone of
a network Inferior quality of network cabling results in network failures and in networks with unreliable performance The equipment used to perform these tests involves certain electrical and mathematical concepts and terms, such as signal, wave, frequency, and noise Understanding this vocabulary is helpful when learning about networking, cabling, and cable testing This chapter corre-sponds to the Module 4 and 5 content from the CCNA 1 online curriculum
■ Chapter 5, “Ethernet Fundamentals,” discusses the operation of Ethernet, Ethernet
framing, error handling, and the different type of the collisions on Ethernet works In addition, this chapter introduces the collision domains and broadcast domains Finally, this chapter describes segmentation and the devices used to create the network segments This chapter corresponds to the Module 6 content from the CCNA 1 online curriculum
net-■ Chapter 6, “Ethernet Technologies and Ethernet Switching,” introduces Layer 2
bridging and switching techniques It introduces the Spanning Tree Protocol (STP), tells how STP works, and covers the STP switch port states This chapter corresponds to the Module 7 and 8 content from the CCNA 1 online curriculum
Trang 30■ Chapter 7, “TCP/IP Protocol Suite and IP Addressing,” presents an overview
of the TCP/IP protocol suite It starts with the history and future of TCP/IP, pares the TCP/IP protocol model to the OSI model, and identifies and describes each layer of the TCP/IP protocol suite This chapter corresponds to the Module 9 content from the CCNA 1 online curriculum
com-■ Chapter 8, “Routing Fundamentals and Subnets,” covers the topics related to the
Internet Protocol (IP) This chapter also discusses the difference between routing and routed protocols, and tells how routers track distance between locations Finally, this chapter introduces the distance vector, link-state, and hybrid routing approaches, as well as how each resolves common routing problems This chapter corresponds to the Module 10 content from the CCNA 1 online curriculum
■ Chapter 9, “TCP/IP Transport and Application Layer,” covers the issues related
to the transport layer and how it uses the services provided by the network layer, such as best path selection and logical addressing, to provide end-to-end commu-nication between source and destination This chapter describes how the trans-port layer regulates the flow of information from source to destination reliably and accurately This chapter corresponds to the Module 11 content from the CCNA 1 online curriculum
■ Chapter 10, “WANs and Routers,” introduces WAN devices, technologies, and
standards In addition, it discusses the function of a router in a WAN This ter corresponds to the Module 1 content from the CCNA 2 online curriculum
chap-■ Chapter 11, “ Router Fundamentals,” describes how to start a router for the first
time by using the correct commands and startup sequence to do an initial uration of the router This chapter also explains the startup sequence of a router and the setup dialog that the router uses to create an initial configuration file using current versions of Cisco IOS Software This chapter corresponds to the Module 2 content from the CCNA 2 online curriculum
config-■ Chapter 12, “Router Configuration,” discusses the router modes and
configura-tion methods for updating a router’s configuraconfigura-tion file It is important that a firm understand Cisco IOS Software and know the procedures for starting a router In addition, this chapter describes the tasks necessary for password recovery This chapter corresponds to the Module 3 content from the CCNA 2 online curriculum
■ Chapter 13, “Learning About Neighboring and Remote Devices,” covers how
to implement, monitor, and maintain Cisco Discovery Protocol by using the correct router commands In addition, this chapter explains the three most used commands This chapter corresponds to the Module 4 content from the CCNA 2 online curriculum
Trang 31xxxi
■ Chapter 14, “Managing Cisco IOS Software,” examines the stages of the router
boot sequence It also covers how to use a variety of Cisco IOS Software source options, execute commands to load Cisco IOS Software onto the router, maintain backup files, and upgrade Cisco IOS Software In addition, this chapter discusses the functions of the configuration register and tells how to determine the version
of the IOS file Finally, this chapter describes how to use a TFTP server as a ware source This chapter corresponds to the Module 5 content from the CCNA 2 online curriculum
soft-■ Chapter 15, “Routing and Routing Protocols,” covers the router’s use and
oper-ations in performing the key internetworking function of the Open System connection (OSI) reference model’s network layer, Layer 3 In addition, this chapter discusses the difference between routing and routed protocols and tells how routers track distance between locations Finally, this chapter introduces distance vector, link-state, and hybrid routing approaches and details how each resolves common routing problems This chapter corresponds to the Module 6 content from the CCNA 2 online curriculum
Inter-■ Chapter 16, “Distance Vector Routing Protocols,” covers the initial configuration
of the router to enable the Routing Information Protocol (RIP) and the Interior Gateway Routing Protocol (IGRP) In addition, this chapter describes how to monitor IP routing protocols This chapter corresponds to the Module 7 content from the CCNA 2 online curriculum.This chapter corresponds to the Module 7 content from the CCNA 2 online curriculum
■ Chapter 17, “TCP/IP Error and Control Messages,” covers ICMP, the ICMP
message format, ICMP error message types, potential causes of specific ICMP error messages, a variety of ICMP control messages used in networks today, and the causes for ICMP control messages This chapter corresponds to the Module 8 content from the CCNA 2 online curriculum
■ Chapter 18, “Basic Router Troubleshooting,” provides an introduction to network
testing It emphasizes the necessity of using a structured approach to shooting Finally, this chapter describers the fundamentals of troubleshooting routers This chapter corresponds to the Module 9 content from the CCNA 2 online curriculum
trouble-■ Chapter 19, “Intermediate TCP,” describes TCP/IP operation to ensure
commu-nication across any set of interconnected networks In addition, this chapter covers the TCP/IP protocol stack components, such as protocols to support file transfer, e-mail, remote login, and other applications This chapter also introduces
Trang 32reliable and unreliable transport layer protocols and details connectionless gram (packet) delivery at the network layer Finally, it explains how ARP and RARP work This chapter corresponds to the Module 10 content from the CCNA 2 online curriculum.
data-■ Chapter 20, “Access Control Lists,” includes tips, considerations, recommendations,
and general guidelines on how to use ACLs, and includes the commands and configurations needed to create ACLs Finally, this chapter provides examples of standard and extended ACLs and tells how to apply ACLs to router interfaces This chapter corresponds to the Module 11 content from the CCNA 2 online curriculum
■ Appendix A, “Structured Cabling,” includes coverage of structured cabling
systems, standards, and codes In addition, this appendix provides coverage of cabling safety, tools of the trade, installation process, finish phase, overview of the cabling business This appendix also provides a cabling case study that covers how to apply all of the information in this chapter to a real-world scenario The material in this appendix does not appear in the online curriculum, but provides some valuable information that you will need to know as a CCNA
■ Appendix B, “Glossary of Key Terms,” provides a compiled list of all the key
terms that appear throughout this book
■ Appendix C, “Check Your Understanding Answer Key,” provides the answers to
the Check Your Understanding questions that you find at the end of each chapter
About the CD-ROM
A CD-ROM accompanies this book to further enhance your learning experience The
CD contains additional chapters not found online, a test engine with CCNA practice exam questions, interactive e-Lab Activities, PhotoZooms of networking equipment and hardware, and instructional Videos and animations that highlight potentially difficult concepts These materials support self-directed study by allowing you to engage in learning and skill building exercises outside of the classroom The CD also provides the following:
■ An easy-to-use graphical user interface
■ Chapter-by-chapter activities and resources
■ Information and activities not found online
Trang 33xxxiii
■ Accurate and concise feedback on practice exam questions
■ Learner-directed practice and study
■ Flexibility for learners of all levels
Finally, these learning tools emphasize not only conceptual material, but also the
impor-tance of practicing what you have learned The CD helps you understand routing and
switching, and make the connection between theory and practice
Trang 35Part I
CCNA 1: Networking Basics
Trang 36Upon completion of this chapter, you will be able to
■ Identify the requirements for Internet connection
■ Identify the major components of a personal computer
■ Name the Ethernet adapter used for a laptop computer
■ State the functions of network interface cards (NICs)
■ List the components needed for NIC installation
■ Identify the functions of the ping command
■ Identify the features of web browsers
■ Describe the units used to measure the size of digital data
■ Convert a decimal number to a binary number
■ Convert a binary number to a decimal number
■ Convert a hexadecimal number to a binary number
■ Convert a binary number to a hexadecimal number
Trang 37Chapter 1
Introduction to Networking
This chapter presents the basics of computers and connection to the Internet It also introduces different number systems and the processes used to convert a number from one number system to another
Please be sure to look at this chapter’s associated e-Lab Activities, Videos, and Zooms that you will find on the CD-ROM accompanying this book These CD elements are designed to supplement the material and reinforce the concepts introduced in this chapter
Photo-The Fundamentals of Internet Connectivity
To understand the role that computers play in a networking system, consider the Internet.The Internet can be thought of as a tree with computers as leaves Computers are the sources and receivers of information by way of the Internet Computers can function without the Internet, but the Internet cannot exist without computers The Internet is growing rapidly, and users are becoming increasingly dependent on it for a myriad of services
Computers, along with being an integral part of a network, also play a vital role in the world of work Businesses use their computers for a variety of purposes, but they also use them in some common ways They use servers to store important data to manage customer and employee accounts They use spreadsheet software to organize financial information, word processor software to maintain records and correspondence, and browsers to access internal and external websites
High-speed accesses to the Internet, such as cable modem and DSL services, are now available to the home and small office, which is increasing the demand for support ser-vices No longer satisfied with a single computer connected to the Internet, the consumer needs the tools to be able to share the connection
Trang 38The Internet is the largest data network in the world The Internet consists of a tude of interconnected networks, both large and small At the edge of this giant network
multi-is the individual consumer computer
Connection to the Internet can be broken down into the following components:
con-necting a specialized expansion card, such as a modem or a network interface card (NIC), to a PC with a cable The physical connection is used to transfer signals between PCs in the local network and remote devices on the Internet
how devices on a network communicate Connections to the Internet may use multiple protocols The Transmission Control Protocol/Internet Protocol (TCP/ IP) suite is the primary protocol used on the Internet TCP/IP is a suite of proto-cols that work together to send and receive data You learn more about TCP/IP
in Chapter 7, “TCP/IP Protocol Suite and IP Addressing.”
informa-tion in a comprehensible format is the last part of the connecinforma-tion Applicainforma-tions work with protocols to send and receive data across the Internet A web browser
displays HTML as a web page File Transfer Protocol (FTP)is used to download files and programs from the Internet Web browsers also use proprietary plug-in applications to display special data types such as video, audio, and animation.This introductory view might make the Internet seem like an overly simple process However, as this topic is explored in greater depth later in this book, it will become apparent that sending data across the Internet is a complicated task
PC Basics
Because computers are important building blocks in a network, it is important to be able to recognize and name the major components of a PC Think of the internal com-ponents of a PC as a network of devices, all attached to the system bus In a sense, a
PC is a small computer network
Many networking devices, such as routers and switches, are special-purpose ers and have many of the same parts as normal PCs For a computer to be a reliable means of obtaining information, it must be in good working order You should be able
comput-to recognize, name, and state the purpose of the PC components (this information tains to laptops as well) described in the following sections
Trang 39per-PC Basics 7
Electronic Components
Electronic components are unique in that they are designed to conduct or transmit
data or signals in electronic form Most electronic components are found on the
motherboard and expansion cards that plug into the motherboard Here are some
of the parts that commonly are found on electronic components:
■ Transistor—A device that amplifies a signal or opens and closes a circuit
Micro-processors can have millions of transistors
■ Integrated circuit (IC)—A device made of semiconductor material It contains
many transistors and performs a specific task
■ Resistor—A device that is made of material that opposes the flow of electric
current
■ Capacitor—An electronic component that stores energy in the form of an
electro-static field It consists of two conducting metal plates separated by an insulating material
■ Connector—A port or interface that a cable plugs into Examples include serial,
parallel, USB, and disk drive interfaces
■ Light emitting diode (LED)—A semiconductor device that emits light when a
current passes through it These are commonly used as indicator lights
PC Components
PC components are typically thought of as packaged or add-on parts that provide
additional functionality to a PC This is in contrast to vital electronic components
that are necessary in every PC These include things such as media drives, memory,
hard drives, processors, and the power supply Here are some of the most common PC
components:
and other electronic components are placed Examples include the motherboard and various expansion adapters
This can also be a CD-RW (compact disc read-write) drive or a DVD (digital video disc) drive or a combination of all three in one drive
calculations take place (see Figure 1-1)
device in the computer
Trang 40Figure 1-1 Central Processing Unit
Figure 1-2 Floppy Disk Drive
of microprocessors, including the main CPU
mother-board is crucial because it is the computer’s nerve center Everything else in the system plugs into it, is controlled by it, and depends on it to communicate with other devices in the system
■ Bus—A collection of circuits through which data is transmitted from one part of
a computer to another The bus connects all the internal computer components
to the CPU The Industry-Standard Architecture (ISA) and the peripheral nent interconnect (PCI) are two types of buses
have new data written to it and can have stored data read from it RAM is the main working area used by the CPU for most processing and operations A draw-back of RAM is that it requires electrical power to maintain data storage If the computer is turned off or loses power, all data stored in RAM is lost unless the data was previously saved to disk Memory boards with RAM chips plug into the motherboard