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Accessing the WAN: CCNA Exploration Companion Guide


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  • About
  • Description
  • Sample Content
  • Updates


The all-new and only authorized textbook for the new Cisco Networking Academy CCNA Exploration Accessing the WAN curriculum

  • A portable reference that supports the topics in the all-new Cisco Networking Academy CCNA Exploration Accessing the WAN curriculum aligning 1:1 with course modules
  • Features improved readability, enhanced topic explanations, real-world examples, and all-new graphical presentations
  • Written and Edited by leading Academy Instructors

  • Copyright 2012
  • Edition: 1st
  • Book
  • ISBN-10: 1-58713-349-0
  • ISBN-13: 978-1-58713-349-7

Each new purchase of an Exploration Companion guide comes with an exclusive coupon code that can be used to Save 65% on these two additional study resources:

1.     CCNA ICND2 640-822 Official Cert Guide, Premium Edition eBook and Practice Test (

2.     Accessing the WAN Companion Guide eBook (


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.

Table of Contents

&atext-align=left align=left>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

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