Accessing the WAN: CCNA Exploration Companion Guide / Edition 2

by Bob Vachon, Rick Graziani

Overview

Accessing the WAN

CCNA Exploration Companion Guide

Bob Vachon

Rick Graziani

Accessing the WAN, CCNA Exploration Companion Guide is the official supplemental textbook for the Accessing the WAN course in the Cisco Networking Academy CCNA Exploration curriculum version 4. This course discusses the WAN technologies and network services required by converged applications in enterprise networks. The Companion Guide, written and edited by Networking Academy instructors, is designed as a portable desk reference to use anytime, anywhere. The book’s features reinforce the material in the course to help you focus on important concepts and organize your study time for exams.

New and improved features help you study and succeed in this course:

• Chapter objectives: Review core concepts by answering the focus questions listed at the beginning of each chapter.
• Key terms: Refer to the updated lists of networking vocabulary introduced and turn to the highlighted terms in context in each chapter.
• Glossary: Consult the all-new comprehensive glossary with more than 250 terms.
• Check Your Understanding questions and answer key: Evaluate your readiness with the updated end-of-chapter questions that match the style of questions you see on the online course quizzes. The answer key explains each answer.
• Challenge questions and activities: Strive to ace more challenging review questions and activities designed to prepare you for the complex styles of questions you might see on the CCNA exam. The answer key explains each answer.

Bob Vachon is the coordinator of the Computer Systems Technology program and teaches networking infrastructure courses at Cambrian College in Sudbury, Ontario, Canada. Bob has worked and taught in the computer networking and information technology field for 25 years and is a scholar graduate of Cambrian College.

Rick Graziani teaches computer science and computer networking courses at Cabrillo College in Aptos, California. Rick has worked and taught in the computer networking and information technology field for 30 years.

How To: Look for this icon to study the steps that you need to learn to perform certain tasks.

Packet Tracer Activities: Explore networking concepts in activities interspersed throughout some chapters using

Packet Tracer v4.1 developed by Cisco. The files for these activities are on the accompanying CD-ROM.

Also available for the Accessing the WAN Course

Accessing the WAN,

CCNA Exploration

Labs and Study Guide

ISBN-10: 1-58713-201-X

ISBN-13: 978-1-58713-201-8

Companion CD-ROM

The CD-ROM provides many useful tools and information to support your education:

Packet Tracer Activity exercise files

• A Guide to Using a Networker’s Journal booklet
• Taking Notes: A .txt file of the chapter objectives
• More IT Career Information
• Tips on Lifelong Learning in Networking

This book is part of the Cisco Networking Academy Series from Cisco Press. The products in this series support and complement the Cisco Networking Academy online curriculum.

Product Details

ISBN-13:	9781587132056
Publisher:	Cisco Press
Publication date:	05/14/2008
Series:	Companion Guide Series
Edition description:	New Edition
Pages:	704
Product dimensions:	7.90(w) x 9.30(h) x 1.40(d)

About the Author

Bob Vachon is the coordinator of the Computer Systems Technology program at Cambrian College in Sudbury, Ontario, Canada, where he teaches networking infrastructure courses.

He has worked and taught in the computer networking and information technology field since 1984. He is a scholar graduate of Cambrian College, and he received the prestigious

Teaching Excellence Award in 1997. Vachon has been a Cisco Networking Academy instructor since 1999 and has been CCNP certified since 2002. He has worked with Cisco

as team lead, author, CCNP certification assessment developer, and subject matter expert on a variety of projects, including CCNA, CCNP, and global partner training courses. He

enjoys playing the guitar and being outdoors, either working in his gardens or white-water canoe tripping.

Rick Graziani teaches computer science and computer networking courses at Cabrillo College in Aptos, California. He has worked and taught in the computer networking and

information technology fields for almost 30 years. Before that, he worked in IT for various companies, including Santa Cruz Operation, Tandem Computers, and Lockheed Missiles

and Space Corporation. He holds an M.A. in computer science and systems theory from California State University Monterey Bay. Graziani also does consulting work for Cisco and

other companies. When he is not working, he is most likely surfing. He is an avid surfer who enjoys longboarding at his favorite Santa Cruz surf breaks.

Read an Excerpt

IntroductionIntroduction

The Cisco Networking Academy is a comprehensive e-learning program that provides students with Internet technology skills. A Networking Academy delivers web-based content, online assessment, student performance tracking, and hands-on labs to prepare students for industry-standard certifications. The CCNA curriculum includes four courses oriented around the topics on the Cisco Certified Network Associate (CCNA) certification.

Accessing the WAN, CCNA Exploration Companion Guide is the official supplement textbook to be used with version 4 of the CCNA Exploration Accessing the WAN online curriculum of the Networking Academy.

This book goes beyond earlier editions of the Cisco Press Companion Guides by providing many alternative explanations and examples as compared with the course. You can use the online curriculum as normal and use this Companion Guide to help solidify your understanding of all the topics through the alternative examples.

The basis for this book as well as the online curriculum is to help you understand several WAN technologies, including PPP and Frame Relay, and related topics, such as access control lists and Network Address Translation. This book also introduces other WAN technologies, such as DSL, cable modems, and Virtual Private Networks (VPNs).

Goals of This Book

First and foremost, by providing a fresh, complementary perspective on the topics, this book is intended to help you learn all the required materials of the Exploration Accessing the WAN course in the Networking Academy CCNA curriculum. As a secondary goal, the text is intended as a mobile replacement for the online curriculum for individuals who do not always have Internet access. In those cases, you can instead read the appropriate sections of the book, as directed by your instructor, and learn the same material that is covered in the online curriculum. Another secondary goal is to serve as your offline study material and help you prepare for the CCNA exam.

Audience for This Book

This book's main audience is anyone taking the CCNA Exploration Accessing the WAN course of the Cisco Networking Academy curriculum. Many Academies use this textbook as a required tool in the course, and other Academies recommend the Companion Guides as an additional source of study and practice materials.

The secondary audience for this book includes people taking CCNA-related classes from professional training organizations. This book can also be used for college- and university-level networking courses, as well as by anyone who wants to gain a detailed understanding of wide-area networks.

Book Features

The educational features of this book focus on supporting topic coverage, readability, and practice of the course material to facilitate your full understanding of the course material.

Topic Coverage

The following features give you a thorough overview of the topics covered in each chapter so that you can make constructive use of your study time:

• Objectives: Listed at the beginning of each chapter, the objectives reference the core concepts covered in the chapter. The objectives match the objectives stated in the corresponding chapters of the online curriculum. However, the question format in the Companion Guide encourages you to think about finding the answers as you read the chapter.

• "How-to" feature: When this book covers a set of steps that you need to perform for certain tasks, this book lists the steps as a how-to list. When you are studying, the How To icon helps you easily find this feature as you skim through the book.

• Notes, tips, cautions, and warnings: These are sidebars that point out interesting facts, time-saving methods, and important safety issues.

• Chapter summaries: At the end of each chapter is a summary of the chapter's key concepts. It provides a synopsis of the chapter and serves as a study aid.

Readability

The authors have compiled, edited, and in some cases rewritten the material so that it has a more conversational tone that follows a consistent and accessible reading level. In addition, the following features have been updated to aid your understanding of the networking vocabulary:

• Key terms: Each chapter begins with a list of key terms, along with a page number reference. The terms are listed in the order in which they are explained in the chapter. This handy reference allows you to see a term, flip to the page where it appears, and see it used in context. The glossary defines all the key terms.

• Glossary: This book contains an all-new glossary with more than 240 terms.

Practice

Practice makes perfect. This new Companion Guide offers you ample opportunities to put what you learn into practice. You will find the following features valuable and effective in reinforcing the instruction that you receive:

• Check Your Understanding questions and answer key: Updated review questions are presented at the end of each chapter as a self-assessment tool. These questions match the style of questions that you see in the online course. The appendix, "Check Your Understanding and Challenge Questions Answer Key," provides the answers to all the questions and includes an explanation of each answer.

• (New) Challenge questions and activities: Additional—and more challenging—review questions and activities are presented at the end of each chapter. These questions are designed to be similar to the more complex styles of questions you might see on the CCNA exam. This section might also include activities to help prepare you for the exams. Appendix A provides the answers.

• Packet Tracer activities: Interspersed throughout the chapters, you'll find many opportunities to work with the Cisco Packet Tracer tool. Packet Tracer allows you to create networks, visualize how packets flow in the network, and use basic testing tools to determine whether the network would work. When you see this icon, you can use Packet Tracer with the listed file to perform a task suggested in this book. The activity files are available on this book's CD-ROM; Packet Tracer software is available through the Academy Connection website. Ask your instructor for access to Packet Tracer.

Labs and Study Guide

The supplementary book Accessing the WAN, CCNA Exploration Labs and Study Guide by Cisco Press (ISBN: 1-58713-201-x) contains all the labs from the curriculum plus additional challenge labs and study guide material. The end of each chapter of this Companion Guide indicates with icons what labs, activities, and Packet Tracer activities are available in the Labs and Study Guide.

• Lab references: This icon notes the hands-on labs created for this chapter in the online curriculum. In Accessing the WAN, CCNA Exploration Labs and Study Guide you will also find additional labs and study guide material created by the author of that book.

• (New) Packet Tracer Companion activities: Many of the hands-on labs include Packet Tracer Companion activities, where you can use Packet Tracer to complete a simulation of the lab. Look for this icon in Accessing the WAN, CCNA Exploration Labs and Study Guide for hands-on labs that have a Packet Tracer Companion.

• (New) Packet Tracer Skills Integration Challenge activities: These activities require you to pull together several skills you learned from the chapter to successfully complete one comprehensive exercise. Look for this icon in Accessing the WAN, CCNA Exploration Labs and Study Guide for instructions on how to perform the Packet Tracer Skills Integration Challenge for this chapter.

A Word About Packet Tracer Software and Activities

Packet Tracer is a self-paced, visual, interactive teaching and learning tool developed by Cisco. Lab activities are an important part of networking education. However, lab equipment can be a scarce resource. Packet Tracer provides a visual simulation of equipment and network processes to offset the challenge of limited equipment. Students can spend as much time as they like completing standard lab exercises through Packet Tracer, and they have the option to work from home. Although Packet Tracer is not a substitute for real equipment, it allows students to practice using a command-line interface. This "e-doing" capability is a fundamental component of learning how to configure routers and switches from the command line.

Packet Tracer version 4.x is available only to Cisco Networking Academies through the Academy Connection website. Ask your instructor for access to Packet Tracer.

The course essentially includes three different types of Packet Tracer activities. This book uses icons to indicate which type of Packet Tracer activity is available. The icons are intended to give you a sense of the activity's purpose and the amount of time you'll need to complete it. The three types of Packet Tracer activities are as follows:

• Packet Tracer Activity: This icon identifies straightforward exercises interspersed throughout the chapters, where you can practice or visualize a specific topic. The activity files for these exercises are available on the book's CD-ROM. These activities take less time to complete than the Packet Tracer Companion and Challenge activities.

• Packet Tracer Companion: This icon identifies exercises that correspond to the course's hands-on labs. You can use Packet Tracer to complete a simulation of the hands-on lab or complete a similar "lab." The Companion Guide points these out at the end of each chapter, but look for this icon and the associated exercise file in Accessing the WAN, CCNA Exploration Labs and Study Guide for hands-on labs that have a Packet Tracer Companion.

• Packet Tracer Skills Integration Challenge: This icon identifies activities that require you to pull together several skills you learned from the chapter to successfully complete one comprehensive exercise. The Companion Guide points these out at the end of each chapter, but look for this icon in Accessing the WAN, CCNA Exploration Labs and Study Guide for instructions on how to perform the Packet Tracer Skills Integration Challenge for this chapter.

How This Book Is Organized

The book covers the major topic headings in the same sequence as the online curriculum for the CCNA Exploration Accessing the WAN course. This book has eight chapters, with the same numbers and similar names as the online course chapters.

If you're reading this book without being in the CCNA Accessing the WAN class, or if you're just using this book for self-study, the sequence of topics in each chapter provides a logical sequence for learning the material presented.

• Chapter 1, "Introduction to WANs," provides an overview of the options available for designing enterprise WANs, the technologies available to implement them, and the terminology used to discuss them. You will learn about selecting the appropriate WAN technologies, services, and devices to meet the changing business requirements of an evolving enterprise.

• Chapter 2, "PPP," examines PPP, including its roots in HDLC, PPP concepts, PPP layered architecture, and configuring PPP. Configuring PPP with authentication using PAP and CHAP are also discussed.

• Chapter 3, "Frame Relay," examines the Frame Relay protocol. Basic Frame Relay concepts are discussed, including encapsulation, topologies, and address mapping. Various Frame Relay configuration techniques are examined, including the use of static Frame Relay maps, the use of inverse ARP, and configuring Frame Relay on subinterfaces.

• Chapter 4, "Network Security," covers the threats and attacks that face many of today's networks. Security policies and mitigation techniques are discussed. Securing networks and devices is examined, including an introduction to Cisco SDM. Managing Cisco IOS images is also discussed in this chapter, including password recovery and restoring IOS images.

• Chapter 5, "ACLs," discusses ACL operation and guidelines using standard, extended, and named ACLs. Configuring ACLs is examined, including using wildcard masks, monitoring ACLs, and applying ACLs to interfaces. Dynamic ACLs, reflexive ACLs, and time-based ACLs are introduced.

• Chapter 6, "Teleworker Services," discusses how organizations can provide secure, fast, and reliable remote network connections for teleworkers. This chapter introduces DSL, cable modem, and broadband wireless. VPNs and IPsec also are discussed.

• Chapter 7, "IP Addressing Services," discusses DHCP, NAT, and IPv6. This chapter includes both the concepts and configurations needed to implement these technologies.

• Chapter 8, "Network Troubleshooting," discusses documenting your network, creating a baseline, and the troubleshooting tools and methodologies used in diagnosing network issues.

• The appendix, "Check Your Understanding and Challenge Questions Answer Key," provides the answers to the Check Your Understanding questions at the end of each chapter. It also includes answers for the Challenge Questions and Activities that conclude most chapters.

• The glossary defines all the key terms that appear throughout this book.

About the CD-ROM

The CD-ROM included with this book provides many useful tools and information to support your education:

• Packet Tracer Activity files: These are files to work through the Packet Tracer Activities referenced throughout the book, as indicated by the Packet Tracer Activity icon.

• Taking Notes: This section includes a .txt file of the chapter objectives to serve as a general outline of the key topics of which you need to take note. The practice of taking clear, consistent notes is an important skill not only for learning and studying the material but for on-the-job success as well. Also included in this section is "A Guide to Using a Networker's Journal" PDF booklet providing important insight into the value of the practice of using a journal, how to organize a professional journal, and some best practices on what, and what not, to take note of in your journal.

• IT Career Information: This section includes a student guide to applying the toolkit approach to your career development. Learn more about entering the world of information technology as a career by reading two informational chapters excerpted from The IT Career Builder's Toolkit: "The Job Search" and "The Interview."

• Lifelong Learning in Networking: As you embark on a technology career, you will notice that it is ever-changing and evolving. This career path provides new and exciting opportunities to learn new technologies and their applications. Cisco Press is one of the key resources to plug into on your quest for knowledge. This section of the CD-ROM provides an orientation to the information available to you and tips on how to tap into these resources for lifelong learning.

About the Cisco Press Website for This Book

Cisco Press may provide additional content that you can access by registering your book at the ciscopress.com website. Becoming a member and registering is free, and you then gain access to exclusive deals on other resources from Cisco Press.

To register this book, go to http://www.ciscopress.com/bookstore/register.asp and enter the book's ISBN, located on the back cover. You'll then be prompted to log in or to join ciscopress.com to continue the registration.

After you register this book, a link to the supplemental content will be listed on your My Registered Books page.

© Copyright Pearson Education. All rights reserved.

Table of Contents

Chapter 1 Introduction to WANs 1

Objectives 1

Key Terms 1

Introducing Wide-Area Networks (WANs) 3

What Is a WAN? 3

Why Are WANs Necessary? 5

The Evolving Enterprise 5

Businesses and Their Networks 5

Small Office (Single LAN) 6

Campus (Multiple LANs) 6

Branch (WAN) 8

Distributed (Global) 9

The Evolving Network Model 11

The Hierarchical Design Model 11

The Enterprise Architecture 13

WAN Technology Concepts 17

WAN Technology Overview 17

WAN Physical Layer Concepts 18

WAN Data Link Layer Concepts 23

WAN Switching Concepts 26

WAN Connection Options 29

WAN Link Connection Options 29

Dedicated Connection Link Options 31

Circuit-Switched Connection Options 32

Packet-Switched Connection Options 35

I nternet Connection Options 38

Choosing a WAN Link Connection 44

Summary 48

Labs 49

Check Your Understanding 50

Challenge Questions and Activities 54

Chapter 2 PPP 55

Objectives 55

Key Terms 55

Introducing Serial Communications 56

How Does Serial Communication Work? 56

Serial Communication Standards 59

TDM 61

Demarcation Point 66

Data Terminal Equipment and Data Communications Equipment 67

HDLC Encapsulation 72

Configuring HDLC Encapsulation 75

Troubleshooting Serial Interfaces 76

PPP Concepts 83

Introducing PPP 83

PPP Layered Architecture 84

PPP Frame Structure 87

Establishing a PPP Session 88

Establishing a Link with LCP 89

NCP Explained 95

PPP Configuration Options 97

PPP Configuration Commands 98

Verifying a Serial PPP Encapsulation Configuration 101

Troubleshooting PPP Encapsulation 102

PPP Authentication Protocols 108

Password Authentication Protocol 109

Challenge Handshake Authentication Protocol (CHAP) 110

PPP Encapsulation and Authentication Process 112

Configuring PPP with Authentication 115

Troubleshooting a PPP Configuration with Authentication 118

Summary 120

Labs 120

Check Your Understanding 122

Challenge Questions and Activities 126

Chapter 3 Frame Relay 127

Objectives 127

Key Terms 127

Introduction 128

Basic Frame Relay Concepts 128

Introducing Frame Relay 128

Virtual Circuits 134

Frame Relay Encapsulation 140

Frame Relay Topologies 141

Frame Relay Address Mapping 145

Configuring Frame Relay 152

Enabling Frame Relay Encapsulation 153

Configuring Static Frame Relay Maps 156

Advanced Frame Relay Concepts 159

Solving Reachability Issues 159

Frame Relay Subinterfaces 161

Paying for Frame Relay 162

Frame Relay Flow Control 166

Configuring Advanced Frame Relay 168

Configuring Frame Relay Subinterfaces 168

Verifying Frame Relay Operation 171

Troubleshooting Frame Relay Configuration 178

Summary 180

Labs 181

Check Your Understanding 182

Challenge Questions and Activities 188

To Learn More 188

Chapter 4 Network Security 189

Objectives 189

Key Terms 189

Introduction to Network Security 190

Why Is Network Security Important? 190

Common Security Threats 199

Types of Network Attacks 206

General Mitigation Techniques 219

The Network Security Wheel 226

The Enterprise Security Policy 229

Securing Cisco Routers 232

Router Security Issues 232

Applying Cisco IOS Security Features to Routers 235

Securing Router Network Services 250

Vulnerable Router Services and Interfaces 250

Securing Routing Protocols 256

Locking Down Your Router with Cisco AutoSecure 263

Using Cisco SDM 264

Cisco SDM Overview 264

Configuring Your Router to Support SDM 265

Starting SDM 267

The SDM Interface 269

Cisco SDM Wizards 272

Locking Down a Router with SDM 272

Secure Router Management 275

Maintaining Cisco IOS Software Images 275

Managing Cisco IOS Images 276

Managing Cisco IOS Images 283

Backing Up and Upgrading a Software Image 284

Recovering Software Images 288

Troubleshooting Cisco IOS Configurations 294

Recovering a Lost Password 297

Summary 301

Labs 301

Check Your Understanding 302

Challenge Questions and Activities 308

Chapter 5 ACLs 309

Objectives 309

Key Terms 309

Using ACLs to Secure Networks 310

A TCP Conversation 310

Packet Filtering 313

What Is an ACL? 316

ACL Operation 318

Types of Cisco ACLs 322

How a Standard ACL Works 323

Numbering and Naming ACLs 323

Where to Place ACLs 324

General Guidelines for Creating ACLs 327

Configuring Standard ACLs 327

Entering Criteria Statements 327

Configuring a Standard ACL 328

ACL Wildcard Masking 332

Applying Standard ACLs to Interfaces 339

Editing Numbered ACLs 343

Creating Standard Named ACLs 345

Monitoring and Verifying ACLs 346

Editing Named ACLs 347

Configuring an Extended ACL 348

Extended ACLs 349

Configuring Extended ACLs 351

Applying Extended ACLs to the Interfaces 353

Creating Named Extended ACLs 355

Configure Complex ACLs 357

What Are Complex ACLs? 357

Dynamic ACLs 358

Reflexive ACLs 360

Time-Based ACLs 363

Troubleshooting Common ACL Errors 364

Summary 368

Labs 368

Check Your Understanding 369

Challenge Questions and Activities 375

Chapter 6 Teleworker Services 377

Objectives 377

Key Terms 377

Business Requirements for Teleworker Services 379

The Business Requirements for Teleworker Services 379

The Teleworker Solution 380

Broadband Services 384

Connecting Teleworkers to the WAN 384

Cable 385

DSL 391

Broadband Wireless 396

VPN Technology 401

VPNs and Their Benefits 402

Types of VPNs 405

VPN Components 407

Characteristics of Secure VPNs 408

VPN Tunneling 409

VPN Data Confidentiality and Integrity 410

IPsec Security Protocols 416

Summary 419

Labs 419

Check Your Understanding 419

Challenge Questions and Activities 423

Chapter 7 IP Addressing Services 429

Objectives 429

Key Terms 429

Introduction 431

DHCP 431

Introduction to DHCP 432

DHCP Operation 432

BOOTP and DHCP 435

Configuring a Cisco Router as a DHCP Server 440

Configuring a DHCP Client 447

DHCP Relay 449

Configuring a DHCP Server Using SDM 453

Troubleshooting DHCP Configuration 456

Scaling Networks with NAT 460

What Is NAT? 462

Benefits and Drawbacks of Using NAT 468

Configuring Static NAT 470

Configuring Dynamic NAT 471

Configuring NAT Overload for a Single Public IP Address 473

Configuring NAT Overload for a Pool of Public IP Addresses 475

Configuring Port Forwarding 477

Verifying NAT and NAT Overload 479

Troubleshooting NAT and NAT Overload Configuration 483

IPv6 485

Reasons for Using IPv6 489

IPv6 Addressing 493

IPv6 Transition Strategies 499

Cisco IOS Dual Stack 500

IPv6 Tunneling 502

Routing Configurations with IPv6 503

Configuring IPv6 Addresses 506

Configuring RIPng with IPv6 508

Summary 512

Labs 512

Check Your Understanding 514

Challenge Questions and Activities 522

Chapter 8 Network Troubleshooting 525

Objectives 525

Key Terms 525

Establishing the Network Performance Baseline 526

Documenting Your Network 526

Network Documentation Process 533

Why Is Establishing a Network Baseline Important? 535

Steps for Establishing a Network Baseline 535

Troubleshooting Methodologies and Tools 541

A General Approach to Troubleshooting 541

Using Layered Models for Troubleshooting 541

General Troubleshooting Procedures 544

Troubleshooting Methods 545

Gathering Symptoms 548

Troubleshooting Tools 551

Review of WAN Communications 560

WAN Communications 560

Steps in WAN Design 561

WAN Traffic Considerations 562

WAN Topology Considerations 564

WAN Connection Technologies 567

WAN Bandwidth Considerations 568

Common WAN Implementations Issues 569

WAN Troubleshooting from an ISP’s Perspective 570

Network Troubleshooting 571

Physical Layer Troubleshooting 573

Data Link Layer Troubleshooting 577

Network Layer Troubleshooting 584

Transport Layer Troubleshooting 586

Application Layer Troubleshooting 589

Summary 595

Labs 595

Check Your Understanding 596

Challenge Questions and Activities 600

Appendix 601

Glossary 637

Preface

Introduction

The Cisco Networking Academy is a comprehensive e-learning program that provides students with Internet technology skills. A Networking Academy delivers web-based content, online assessment, student performance tracking, and hands-on labs to prepare students for industry-standard certifications. The CCNA curriculum includes four courses oriented around the topics on the Cisco Certified Network Associate (CCNA) certification.

Accessing the WAN, CCNA Exploration Companion Guide is the official supplement textbook to be used with version 4 of the CCNA Exploration Accessing the WAN online curriculum of the Networking Academy.

This book goes beyond earlier editions of the Cisco Press Companion Guides by providing many alternative explanations and examples as compared with the course. You can use the online curriculum as normal and use this Companion Guide to help solidify your understanding of all the topics through the alternative examples.

The basis for this book as well as the online curriculum is to help you understand several WAN technologies, including PPP and Frame Relay, and related topics, such as access control lists and Network Address Translation. This book also introduces other WAN technologies, such as DSL, cable modems, and Virtual Private Networks (VPNs).

Goals of This Book

First and foremost, by providing a fresh, complementary perspective on the topics, this book is intended to help you learn all the required materials of the Exploration Accessing the WAN course in the Networking Academy CCNA curriculum. As a secondary goal, the text is intended as a mobile replacement for the online curriculum for individuals who do not always have Internet access. In those cases, you can instead read the appropriate sections of the book, as directed by your instructor, and learn the same material that is covered in the online curriculum. Another secondary goal is to serve as your offline study material and help you prepare for the CCNA exam.

Audience for This Book

This book's main audience is anyone taking the CCNA Exploration Accessing the WAN course of the Cisco Networking Academy curriculum. Many Academies use this textbook as a required tool in the course, and other Academies recommend the Companion Guides as an additional source of study and practice materials.

The secondary audience for this book includes people taking CCNA-related classes from professional training organizations. This book can also be used for college- and university-level networking courses, as well as by anyone who wants to gain a detailed understanding of wide-area networks.

Book Features

The educational features of this book focus on supporting topic coverage, readability, and practice of the course material to facilitate your full understanding of the course material.

Topic Coverage

The following features give you a thorough overview of the topics covered in each chapter so that you can make constructive use of your study time:

• Objectives: Listed at the beginning of each chapter, the objectives reference the core concepts covered in the chapter. The objectives match the objectives stated in the corresponding chapters of the online curriculum. However, the question format in the Companion Guide encourages you to think about finding the answers as you read the chapter.

• "How-to" feature: When this book covers a set of steps that you need to perform for certain tasks, this book lists the steps as a how-to list. When you are studying, the How To icon helps you easily find this feature as you skim through the book.

• Notes, tips, cautions, and warnings: These are sidebars that point out interesting facts, time-saving methods, and important safety issues.

• Chapter summaries: At the end of each chapter is a summary of the chapter's key concepts. It provides a synopsis of the chapter and serves as a study aid.

Readability

The authors have compiled, edited, and in some cases rewritten the material so that it has a more conversational tone that follows a consistent and accessible reading level. In addition, the following features have been updated to aid your understanding of the networking vocabulary:

• Key terms: Each chapter begins with a list of key terms, along with a page number reference. The terms are listed in the order in which they are explained in the chapter. This handy reference allows you to see a term, flip to the page where it appears, and see it used in context. The glossary defines all the key terms.

• Glossary: This book contains an all-new glossary with more than 240 terms.

Practice

Practice makes perfect. This new Companion Guide offers you ample opportunities to put what you learn into practice. You will find the following features valuable and effective in reinforcing the instruction that you receive:

• Check Your Understanding questions and answer key: Updated review questions are presented at the end of each chapter as a self-assessment tool. These questions match the style of questions that you see in the online course. The appendix, "Check Your Understanding and Challenge Questions Answer Key," provides the answers to all the questions and includes an explanation of each answer.

• (New) Challenge questions and activities: Additional—and more challenging—review questions and activities are presented at the end of each chapter. These questions are designed to be similar to the more complex styles of questions you might see on the CCNA exam. This section might also include activities to help prepare you for the exams. Appendix A provides the answers.

• Packet Tracer activities: Interspersed throughout the chapters, you'll find many opportunities to work with the Cisco Packet Tracer tool. Packet Tracer allows you to create networks, visualize how packets flow in the network, and use basic testing tools to determine whether the network would work. When you see this icon, you can use Packet Tracer with the listed file to perform a task suggested in this book. The activity files are available on this book's CD-ROM; Packet Tracer software is available through the Academy Connection website. Ask your instructor for access to Packet Tracer.

Labs and Study Guide

The supplementary book Accessing the WAN, CCNA Exploration Labs and Study Guide by Cisco Press (ISBN: 1-58713-201-x) contains all the labs from the curriculum plus additional challenge labs and study guide material. The end of each chapter of this Companion Guide indicates with icons what labs, activities, and Packet Tracer activities are available in the Labs and Study Guide.

• Lab references: This icon notes the hands-on labs created for this chapter in the online curriculum. In Accessing the WAN, CCNA Exploration Labs and Study Guide you will also find additional labs and study guide material created by the author of that book.

• (New) Packet Tracer Companion activities: Many of the hands-on labs include Packet Tracer Companion activities, where you can use Packet Tracer to complete a simulation of the lab. Look for this icon in Accessing the WAN, CCNA Exploration Labs and Study Guide for hands-on labs that have a Packet Tracer Companion.

• (New) Packet Tracer Skills Integration Challenge activities: These activities require you to pull together several skills you learned from the chapter to successfully complete one comprehensive exercise. Look for this icon in Accessing the WAN, CCNA Exploration Labs and Study Guide for instructions on how to perform the Packet Tracer Skills Integration Challenge for this chapter.

A Word About Packet Tracer Software and Activities

Packet Tracer is a self-paced, visual, interactive teaching and learning tool developed by Cisco. Lab activities are an important part of networking education. However, lab equipment can be a scarce resource. Packet Tracer provides a visual simulation of equipment and network processes to offset the challenge of limited equipment. Students can spend as much time as they like completing standard lab exercises through Packet Tracer, and they have the option to work from home. Although Packet Tracer is not a substitute for real equipment, it allows students to practice using a command-line interface. This "e-doing" capability is a fundamental component of learning how to configure routers and switches from the command line.

Packet Tracer version 4.x is available only to Cisco Networking Academies through the Academy Connection website. Ask your instructor for access to Packet Tracer.

The course essentially includes three different types of Packet Tracer activities. This book uses icons to indicate which type of Packet Tracer activity is available. The icons are intended to give you a sense of the activity's purpose and the amount of time you'll need to complete it. The three types of Packet Tracer activities are as follows:

• Packet Tracer Activity: This icon identifies straightforward exercises interspersed throughout the chapters, where you can practice or visualize a specific topic. The activity files for these exercises are available on the book's CD-ROM. These activities take less time to complete than the Packet Tracer Companion and Challenge activities.

• Packet Tracer Companion: This icon identifies exercises that correspond to the course's hands-on labs. You can use Packet Tracer to complete a simulation of the hands-on lab or complete a similar "lab." The Companion Guide points these out at the end of each chapter, but look for this icon and the associated exercise file in Accessing the WAN, CCNA Exploration Labs and Study Guide for hands-on labs that have a Packet Tracer Companion.

• Packet Tracer Skills Integration Challenge: This icon identifies activities that require you to pull together several skills you learned from the chapter to successfully complete one comprehensive exercise. The Companion Guide points these out at the end of each chapter, but look for this icon in Accessing the WAN, CCNA Exploration Labs and Study Guide for instructions on how to perform the Packet Tracer Skills Integration Challenge for this chapter.

How This Book Is Organized

The book covers the major topic headings in the same sequence as the online curriculum for the CCNA Exploration Accessing the WAN course. This book has eight chapters, with the same numbers and similar names as the online course chapters.

If you're reading this book without being in the CCNA Accessing the WAN class, or if you're just using this book for self-study, the sequence of topics in each chapter provides a logical sequence for learning the material presented.

• Chapter 1, "Introduction to WANs," provides an overview of the options available for designing enterprise WANs, the technologies available to implement them, and the terminology used to discuss them. You will learn about selecting the appropriate WAN technologies, services, and devices to meet the changing business requirements of an evolving enterprise.

• Chapter 2, "PPP," examines PPP, including its roots in HDLC, PPP concepts, PPP layered architecture, and configuring PPP. Configuring PPP with authentication using PAP and CHAP are also discussed.

• Chapter 3, "Frame Relay," examines the Frame Relay protocol. Basic Frame Relay concepts are discussed, including encapsulation, topologies, and address mapping. Various Frame Relay configuration techniques are examined, including the use of static Frame Relay maps, the use of inverse ARP, and configuring Frame Relay on subinterfaces.

• Chapter 4, "Network Security," covers the threats and attacks that face many of today's networks. Security policies and mitigation techniques are discussed. Securing networks and devices is examined, including an introduction to Cisco SDM. Managing Cisco IOS images is also discussed in this chapter, including password recovery and restoring IOS images.

• Chapter 5, "ACLs," discusses ACL operation and guidelines using standard, extended, and named ACLs. Configuring ACLs is examined, including using wildcard masks, monitoring ACLs, and applying ACLs to interfaces. Dynamic ACLs, reflexive ACLs, and time-based ACLs are introduced.

• Chapter 6, "Teleworker Services," discusses how organizations can provide secure, fast, and reliable remote network connections for teleworkers. This chapter introduces DSL, cable modem, and broadband wireless. VPNs and IPsec also are discussed.

• Chapter 7, "IP Addressing Services," discusses DHCP, NAT, and IPv6. This chapter includes both the concepts and configurations needed to implement these technologies.

• Chapter 8, "Network Troubleshooting," discusses documenting your network, creating a baseline, and the troubleshooting tools and methodologies used in diagnosing network issues.

• The appendix, "Check Your Understanding and Challenge Questions Answer Key," provides the answers to the Check Your Understanding questions at the end of each chapter. It also includes answers for the Challenge Questions and Activities that conclude most chapters.

• The glossary defines all the key terms that appear throughout this book.

About the CD-ROM

The CD-ROM included with this book provides many useful tools and information to support your education:

• Packet Tracer Activity files: These are files to work through the Packet Tracer Activities referenced throughout the book, as indicated by the Packet Tracer Activity icon.

• Taking Notes: This section includes a .txt file of the chapter objectives to serve as a general outline of the key topics of which you need to take note. The practice of taking clear, consistent notes is an important skill not only for learning and studying the material but for on-the-job success as well. Also included in this section is "A Guide to Using a Networker's Journal" PDF booklet providing important insight into the value of the practice of using a journal, how to organize a professional journal, and some best practices on what, and what not, to take note of in your journal.

• IT Career Information: This section includes a student guide to applying the toolkit approach to your career development. Learn more about entering the world of information technology as a career by reading two informational chapters excerpted from The IT Career Builder's Toolkit: "The Job Search" and "The Interview."

• Lifelong Learning in Networking: As you embark on a technology career, you will notice that it is ever-changing and evolving. This career path provides new and exciting opportunities to learn new technologies and their applications. Cisco Press is one of the key resources to plug into on your quest for knowledge. This section of the CD-ROM provides an orientation to the information available to you and tips on how to tap into these resources for lifelong learning.

About the Cisco Press Website for This Book

Cisco Press may provide additional content that you can access by registering your book at the ciscopress.com website. Becoming a member and registering is free, and you then gain access to exclusive deals on other resources from Cisco Press.

To register this book, go to http://www.ciscopress.com/bookstore/register.asp and enter the book's ISBN, located on the back cover. You'll then be prompted to log in or to join ciscopress.com to continue the registration.

After you register this book, a link to the supplemental content will be listed on your My Registered Books page.

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