Accessing the WAN
CCNA Exploration Companion Guide
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,
Labs and Study Guide
**See instructions within the ebook on how to get access to the files from the CD-ROM that accompanies this print book.**
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.
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
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.
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.
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.
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 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: Additionaland more challengingreview 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.
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.
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.
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.
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.
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&atext-align=left align=left>Chapter 1 Introduction to WANs 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
Check Your Understanding 50
Challenge Questions and Activities 54
Chapter 2 PPP 55
Key Terms 55
Introducing Serial Communications 56
How Does Serial Communication Work? 56
Serial Communication Standards 59
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
Check Your Understanding 122
Challenge Questions and Activities 126
Chapter 3 Frame Relay 127
Key Terms 127
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
Check Your Understanding 182
Challenge Questions and Activities 188
To Learn More 188
Chapter 4 Network Security 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
Check Your Understanding 302
Challenge Questions and Activities 308
Chapter 5 ACLs 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
Check Your Understanding 369
Challenge Questions and Activities 375
Chapter 6 Teleworker Services 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
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
Check Your Understanding 419
Challenge Questions and Activities 423
Chapter 7 IP Addressing Services 429
Key Terms 429
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
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
Check Your Understanding 514
Challenge Questions and Activities 522
Chapter 8 Network Troubleshooting 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
Check Your Understanding 596
Challenge Questions and Activities 600