CCNA 1 and 2 Companion Guide, Revised (Cisco Networking Academy Program) part 3 pdf

xxi
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

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How ACLs Work. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .845
ACL Configuration Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . .847
Assigning a Unique Number to Each ACL. . . . . . . . . . . . . . . . .847
Using Wildcard Mask Bits . . . . . . . . . . . . . . . . . . . . . . . . . . . . .848
Using the Wildcard any . . . . . . . . . . . . . . . . . . . . . . . . . . . . .850
Using the Wildcard host . . . . . . . . . . . . . . . . . . . . . . . . . . . . .851
Standard ACLs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .852
Extended ACLs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .855
Configuring Extended ACLs for ICMP. . . . . . . . . . . . . . . . . .861
Configuring Extended ACLs for IGMP . . . . . . . . . . . . . . . . .861
Configuring Extended ACLs for TCP . . . . . . . . . . . . . . . . . . .861
Configuring Extended ACLs for UDP. . . . . . . . . . . . . . . . . . .862
Extended ACL Defaults . . . . . . . . . . . . . . . . . . . . . . . . . . . . .862
Named ACLs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .863
Placing ACLs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .866
Firewalls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .867
Using ACLs with Firewalls . . . . . . . . . . . . . . . . . . . . . . . . . . .868
Restricting Virtual Terminal Access . . . . . . . . . . . . . . . . . . . . . .869
Verifying ACLs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .870
Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .871
Key Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .872

Check Your Understanding . . . . . . . . . . . . . . . . . . . . . . . . . . . .872
Part III Appendixes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .877
Appendix A Structured Cabling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .879
Mounting Jacks in Drywall . . . . . . . . . . . . . . . . . . . . . . . . . .928
Mounting Jacks in Plaster . . . . . . . . . . . . . . . . . . . . . . . . . . .929
Mounting Jacks in Wood . . . . . . . . . . . . . . . . . . . . . . . . . . . .930
Flush-Mounting a Jack in a Wall . . . . . . . . . . . . . . . . . . . . . .930
Pulling Cable to the Jacks. . . . . . . . . . . . . . . . . . . . . . . . . . . .930
Fishing Cable from Below a Wall . . . . . . . . . . . . . . . . . . . . . .931
Appendix B Glossary of Key Terms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .979
Appendix C Check Your Understanding Answer Key. . . . . . . . . . . . . . . . . .1009
Index 1047

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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
PC
Sun
Workstation
Macintosh
Terminal
File
Server
Web
Server
Cisco Works
Workstation
Printer Laptop
Front End
Processor
Cluster
Controller
Modem
Network Cloud
Token
Ring
Token Ring
Line: Ethernet
FDDI
FDDI

Line: Serial
Line: Switched Serial
IBM
Mainframe

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Command Syntax Conventions
The conventions used to present command syntax in this book are the same conven-
tions used in the Cisco IOS Software Command Reference. The Command Reference
describes these conventions as follows:

■
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.

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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.

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xxvi
I 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.
Kevin Warner
Senior Director, Marketing
Worldwide Education
Cisco Systems, Inc.

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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.
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Book 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 con-
cepts introduced in the chapter and help test your understanding before you
move on to new chapters.
■ 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 corre-
sponds to the Module 1 content from the CCNA 1 online curriculum.
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■ 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 net-
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.
■ 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.
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■ 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, com-
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.
■ 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 chap-
ter corresponds to the Module 1 content from the CCNA 2 online curriculum.
■ 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 config-
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.
■ Chapter 12, “Router Configuration,” discusses the router modes and configura-
tion methods for updating a router’s configuration 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.
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