Routing Protocols and Concepts, CCNA Exploration Companion Guide, 2/e

Rick Graziani, Allan Johnson

  • 出版商: Cisco Press
  • 出版日期: 2007-12-16
  • 售價: $2,270
  • 貴賓價: 9.5$2,157
  • 語言: 英文
  • 頁數: 640
  • 裝訂: Hardcover
  • ISBN: 1587132060
  • ISBN-13: 9781587132063
  • 相關分類: Cisco
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Routing Protocols and Concepts

CCNA Exploration Companion Guide


Routing Protocols and Concepts, CCNA Exploration Companion Guide is the official supplemental textbook for the Routing Protocols and Concepts course in the Cisco Networking Academy® CCNA® Exploration curriculum version 4. This course describes the architecture, components, and operation of routers, and explains the principles of routing and the primary routing protocols. 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 comprehensive glossary with more than 150 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.


Rick Graziani has been a computer science and networking instructor at Cabrillo College since 1994. 


Allan Johnson works full time developing curriculum for Cisco Networking Academy. Allan also is a part-time instructor at Del Mar College in Corpus Christi, Texas.


How To—Look for this icon to study the steps 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 Routing Protocols and Concepts Course:

Routing Protocols and Concepts

CCNA Exploration

Labs and Study Guide

ISBN-10: 1-58713-204-4

ISBN-13: 978-1-58713-204-9


Companion CD-ROM

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

  • Packet Tracer Activity exercise files v4.1
  • 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


Chapter 1 Introduction to Routing and Packet Forwarding


Key Terms

Inside the Router

    Routers Are Computers

        Routers Are at the Network Center

        Routers Determine the Best Path

    Router CPU and Memory




        Flash Memory


    Internetwork Operating System (IOS)

    Router Bootup Process

        Bootup Process

        Command-Line Interface

        Verifying Router Bootup Process

        IOS Version

        ROM Bootstrap Program

        Location of IOS

        CPU and Amount of RAM


        Amount of NVRAM

        Amount of Flash

        Configuration Register

    Router Ports and Interfaces

        Management Ports

        Router Interfaces

        Interfaces Belong to Different Networks

        Example of Router Interfaces

    Routers and the Network Layer

        Routing Is Forwarding Packets

        Routers Operate at Layers 1, 2, and 3

CLI Configuration and Addressing

    Implementing Basic Addressing Schemes

        Populating an Address Table

    Basic Router Configuration

        Host Name and Passwords

        Configuring a Banner

        Router Interface Configuration

        Each Interface Belongs to a Different Network

        Verifying Basic Router Configuration

Building the Routing Table

    Introducing the Routing Table

        show ip route Command

    Directly Connected Networks

    Static Routing

        When to Use Static Routes

    Dynamic Routing

        Automatic Network Discovery

        Maintaining Routing Tables

        IP Routing Protocols

    Routing Table Principles

        Asymmetric Routing

Path Determination and Switching Functions

    Packet Fields and Frame Fields

        Internet Protocol (IP) Packet Format

        MAC Layer Frame Format

    Best Path and Metrics

        Best Path

        Comparing Hop Count and Bandwidth Metrics

    Equal-Cost Load Balancing

        Equal-Cost Paths Versus Unequal-Cost Paths

    Path Determination

    Switching Function

        Path Determination and Switching Function Details

        Path Determination and Switching Function Summary



Check Your Understanding

Challenge Questions and Activities

To Learn More

End Notes

Chapter 2 Static Routing


Key Terms

Routers and the Network

    Role of the Router

    Introducing the Topology

    Examining the Connections of the Router

        Router Connections

        Serial Connectors

        Ethernet Connectors

Router Configuration Review

    Examining Router Interfaces

        Interfaces and Their Statuses

        Additional Commands for Examining Interface Status

    Configuring an Ethernet Interface

        Configuring an Ethernet Interface

        Unsolicited Messages from IOS

        Reading the Routing Table

        Routers Usually Store Network Addresses

    Verifying Ethernet Addresses

        Commands to Verify Interface Configuration

        Ethernet Interfaces Participate in ARP

    Configuring a Serial Interface

    Examining Serial Interfaces

        Physically Connecting a WAN Interface

        Configuring Serial Links in a Lab Environment

        Verifying the Serial Interface Configuration

Exploring Directly Connected Networks

    Verifying Changes to the Routing Table

        Routing Table Concepts

        Observing Routes as They Are Added to the Routing Table

        Changing an IP Address

    Devices on Directly Connected Networks

        Accessing Devices on Directly Connected Networks

        Pings from R2 to

        Pings from R2 to

    Cisco Discovery Protocol (CDP)

        Network Discovery with CDP

        Layer 3 Neighbors

        Layer 2 Neighbors

        CDP Operation

    Using CDP for Network Discovery

        CDP show Commands

        Disabling CDP

Static Routes with “Next-Hop” Addresses

    Purpose and Command Syntax of the ip route Command

        ip route Command

    Configuring Static Routes

        Verifying the Static Route

        Configuring Routes to Two More Remote Networks

    Routing Table Principles and Static Routes

        Applying the Principles

    Resolving to an Exit Interface with a Recursive Route Lookup

        Exit Interface Is Down

Static Routes with Exit Interfaces

    Configuring a Static Route with an Exit Interface

        Static Route and an Exit Interface

    Static Routes and Point-to-Point Networks

    Modifying Static Routes

    Verifying the Static Route Configuration

        Verifying Static Route Changes

    Static Routes with Ethernet Interfaces

        Ethernet Interfaces and ARP

        Sending an ARP Request

        Static Routes and Ethernet Exit Interfaces

        Advantages of Using an Exit Interface with Static Routes

Summary and Default Static Routes

    Summary Static Routes

        Summarizing Routes to Reduce the Size of the Routing Table

        Route Summarization

        Calculating a Summary Route

        Configuring a Summary Route

    Default Static Route

        Most Specific Match

        Configuring a Default Static Route

        Verifying a Default Static Route

Managing and Troubleshooting Static Routes

    Static Routes and Packet Forwarding

        Static Routes and Packet Forwarding

    Troubleshooting a Missing Route

        Troubleshooting a Missing Route

    Solving the Missing Route



Check Your Understanding

Challenge Questions and Activities

To Learn More

    Floating Static Routes

    Discard Route

    Further Reading on Static Routing

End Notes

Chapter 3 Introduction to Dynamic Routing Protocols


Key Terms

Introduction to Dynamic Routing Protocols

    Perspective and Background

        Evolution of Dynamic Routing Protocols

        Role of Dynamic Routing Protocol

    Network Discovery and Routing Table Maintenance

        Purpose of Dynamic Routing Protocols

        Dynamic Routing Protocol Operation

    Dynamic Routing Protocol Advantages

        Static Routing Usage, Advantages, and Disadvantages

        Dynamic Routing Advantages and Disadvantages

Classifying Dynamic Routing Protocols

    IGP and EGP

    Distance Vector and Link-State Routing Protocols

        Distance Vector Routing Protocol Operation

        Link-State Protocol Operation

    Classful and Classless Routing Protocols

        Classful Routing Protocols

        Classless Routing Protocols

    Dynamic Routing Protocols and Convergence


    Purpose of a Metric

    Metrics and Routing Protocols

        Metric Parameters

        Metric Field in the Routing Table

    Load Balancing

Administrative Distance

    Purpose of Administrative Distance

        Multiple Routing Sources

        Purpose of Administrative Distance

    Dynamic Routing Protocols and Administrative Distance

    Static Routes and Administrative Distance

    Directly Connected Networks and Administrative Distance


Activities and Labs

Check Your Understanding

Challenge Questions and Activities

To Learn More

Chapter 4 Distance Vector Routing Protocols


Key Terms

Introduction to Distance Vector Routing Protocols

    Distance Vector Technology

        Meaning of Distance Vector

        Operation of Distance Vector Routing Protocols

    Routing Protocol Algorithms

    Routing Protocol Characteristics

        Comparing Routing Protocol Features

Network Discovery

    Cold Start

    Initial Exchange of Routing Information

    Exchange of Routing Information


Routing Table Maintenance

    Periodic Updates

        Maintaining the Routing Table

        RIP Timers

    Bounded Updates

    Triggered Updates

    Random Jitter

Routing Loops

    Defining a Routing Loop

    Implications of Routing Loops

    Count-to-Infinity Condition

    Preventing Routing Loops by Setting a Maximum Metric Value

    Preventing Routing Loops with Hold-Down Timers

    Preventing Routing Loops with the Split Horizon Rule

        Route Poisoning

        Split Horizon with Poison Reverse

    Preventing Routing Loops with IP and TTL

Distance Vector Routing Protocols Today

    RIP and EIGRP




Activities and Labs

Check Your Understanding

Challenge Questions and Activities

To Learn More

Chapter 5 RIP Version 1


Key Terms

RIPv1: Distance Vector, Classful Routing Protocol

    Background and Perspective

    RIPv1 Characteristics and Message Format

        RIP Characteristics

        RIP Message Format: RIP Header

        RIP Message Format: Route Entry

        Why Are So Many Fields Set to Zero?

    RIP Operation

        RIP Request/Response Process

        IP Address Classes and Classful Routing

    Administrative Distance

Basic RIPv1 Configuration

    RIPv1 Scenario A

    Enabling RIP: router rip Command

    Specifying Networks

Verification and Troubleshooting

    Verifying RIP: show ip route Command

    Verifying RIP: show ip protocols Command

    Verifying RIP: debug ip rip Command

    Passive Interfaces

        Unnecessary RIP Updates Impact Network

        Stopping Unnecessary RIP Updates

Automatic Summarization

    Modified Topology: Scenario B

    Boundary Routers and Automatic Summarization

    Processing RIP Updates

        Rules for Processing RIPv1 Updates

        Example of RIPv1 Processing Updates

    Sending RIP Updates: Using debug to View Automatic


    Advantages and Disadvantages of Automatic Summarization

        Advantages of Automatic Summarization

        Disadvantage of Automatic Summarization

        Discontiguous Topologies Do Not Converge with RIPv1

Default Route and RIPv1

    Modified Topology: Scenario C

    Propagating the Default Route in RIPv1


Activities and Labs

Check Your Understanding

Challenge Questions and Activities

To Learn More

Chapter 6 VLSM and CIDR


Key Terms

Classful and Classless Addressing

    Classful IP Addressing

        High-Order Bits

        IPv4 Classful Addressing Structure

    Classful Routing Protocol

    Classless IP Addressing

        Moving Toward Classless Addressing

        CIDR and Route Summarization

        Classless Routing Protocol


    VLSM in Action

    VLSM and IP Addresses


    Route Summarization

    Calculating Route Summarization


Activities and Labs

Check Your Understanding

Challenge Questions and Activities

To Learn More

Chapter 7 RIPv2


Key Terms

RIPv1 Limitations

    Summary Route


    RFC 1918 Private Addresses

    Cisco Example IP Addresses

    Loopback Interfaces

    RIPv1 Topology Limitations

        Static Routes and Null Interfaces

        Route Redistribution

        Verifying and Testing Connectivity

    RIPv1: Discontiguous Networks

        Examining the Routing Tables

        How Classful Routing Protocols Determine Subnet Masks

    RIPv1: No VLSM Support

    RIPv1: No CIDR Support Static Route

Configuring RIPv2

    Enabling and Verifying RIPv2

    Auto-Summary and RIPv2

    Disabling Auto-Summary in RIPv2

    Verifying RIPv2 Updates


    RIPv2 and VLSM

    RIPv2 and CIDR

Verifying and Troubleshooting RIPv2

    Verification and Troubleshooting Commands

        show ip route Command

        show ip interface brief Command

        show ip protocols Command

        debug ip rip Command

        ping Command

        show running-config Command

    Common RIPv2 Issues



Activities and Labs

Check Your Understanding

Challenge Questions and Activities

To Learn More

Chapter 8 The Routing Table: A Closer Look


Key Terms

The Routing Table Structure

    Lab Topology

    Routing Table Entries

    Level 1 Routes

    Parent and Child Routes: Classful Networks

        Level 1 Parent Route

        Level 2 Child Route

    Parent and Child Routes: Classless Networks

Routing Table Lookup Process

    Steps in the Route Table Lookup Process

        The Route Lookup Process

    Longest Match: Level 1 Network Routes

        Longest Match

        Example: Level 1 Ultimate Route

    Longest Match: Level 1 Parent and Level 2 Child Routes

        Example: Level 1 Parent Route and Level 2 Child Routes

        Example: Route Lookup Process with VLSM

Routing Behavior

    Classful and Classless Routing Behavior

        Topology Changes

    Classful Routing Behavior: no ip classless

    Classful Routing Behavior: Search Process

        Example: R2 Operating with Classful Routing Behavior

    Classless Routing Behavior: ip classless

        The Route Lookup Process

    Classless Routing Behavior: Search Process

        Example: R2 Operating with Classless Routing Behavior

        Classful Route on R3

        Classful vs. Classless Routing Behavior in the Real World


Activities and Labs

Check Your Understanding

Challenge Questions and Activities

To Learn More

End Notes

Chapter 9 EIGRP


Key Terms

Introduction to EIGRP

    EIGRP: An Enhanced Distance Vector Routing Protocol

        Roots of EIGRP: IGRP

        The Algorithm

        Path Determination


    EIGRP Message Format

    Protocol-Dependent Modules

    RTP and EIGRP Packet Types

        EIGRP Packet Types

    Hello Protocol

    EIGRP Bounded Updates

    DUAL: An Introduction

    Administrative Distance


Basic EIGRP Configuration

    EIGRP Network Topology

    Autonomous Systems and Process IDs

        Autonomous System

        Process ID

    The router eigrp Command

    The network Command

        The network Command with a Wildcard Mask

    Verifying EIGRP

    Examining the Routing Table

        Introducing the Null0 Summary Route

        R3 Routing Table

EIGRP Metric Calculation

    EIGRP Composite Metric and the K Values

        The Composite Metric

        Verifying the K Values

    EIGRP Metrics

        Examining the Metric Values





    Using the bandwidth Command

    Calculating the EIGRP Metric



        Adding Bandwidth and Delay


    DUAL Concepts

    Successor and Feasible Distance

    Feasible Successors, Feasibility Condition, and Reported Distance

    Topology Table: Successor and Feasible Successor

    Topology Table: No Feasible Successor

    Finite State Machine

        DUAL FSM

        No Feasible Successor

More EIGRP Configurations

    The Null0 Summary Route

    Disabling Automatic Summarization

    Manual Summarization

        Determining the Summary EIGRP Route

        Configure EIGRP Manual Summarization

    EIGRP Default Route

    Fine-Tuning EIGRP

        EIGRP Bandwidth Utilization

        Configuring Hello Intervals and Hold Times


Activities and Labs

Check Your Understanding

Challenge Questions and Activities

To Learn More

Chapter 10 Link-State Routing Protocols


Key Terms

Link-State Routing

    Link-State Routing Protocols

    Introduction to the SPF Algorithm

    Link-State Routing Process

    Step 1: Learning About Directly Connected Networks


        Link States

    Step 2: Sending Hello Packets to Neighbors

    Step 3: Building the Link-State Packet

    Step 4: Flooding Link-State Packets to Neighbors

    Step 5: Constructing a Link-State Database

    Shortest Path First (SPF) Tree

        Building the SPF Tree

        Determining the Shortest Path

        Generating a Routing Table from the SPF Tree

Implementing Link-State Routing Protocols

    Advantages of a Link-State Routing Protocol

        Builds a Topological Map

        Fast Convergence

        Event-Driven Updates

        Hierarchical Design

    Requirements of a Link-State Routing Protocol

        Memory Requirements

        Processing Requirements

        Bandwidth Requirements

    Comparison of Link-State Routing Protocols


Activities and Labs

Check Your Understanding

Challenge Questions and Activities

To Learn More

Chapter 11 OSPF


Key Terms

Introduction to OSPF

    Background of OSPF

    OSPF Message Encapsulation

    OSPF Packet Types

    Hello Protocol

        Neighbor Establishment

        OSPF Hello and Dead Intervals

        Electing a DR and BDR


    OSPF Algorithm

    Administrative Distance


Basic OSPF Configuration

    Lab Topology

    The router ospf Command

    The network Command

    OSPF Router ID

        Determining the Router ID

        Highest Active IP Address

        Verifying the Router ID

        Loopback Address

        OSPF router-id Command

        Modifying the Router ID

        Duplicate Router IDs

    Verifying OSPF

    Examining the Routing Table

The OSPF Metric

    OSPF Metric

        Reference Bandwidth

        OSPF Accumulates Cost

        Default Bandwidth on Serial Interfaces

    Modifying the Cost of the Link

        The bandwidth Command

        The ip ospf cost Command

        The bandwidth Command vs. the ip ospf cost Command

OSPF and Multiaccess Networks

    Challenges in Multiaccess Networks

        Multiple Adjacencies

        Flooding of LSAs

        Solution: Designated Router

    DR/BDR Election Process

        Topology Change

        DR/BDR Election

        Timing of DR/BDR Election

    OSPF Interface Priority

More OSPF Configuration

    Redistributing an OSPF Default Route


    Fine-Tuning OSPF

        Reference Bandwidth

        Modifying OSPF Intervals


Activities and Labs

Check Your Understanding

Challenge Questions and Activities

To Learn More

Appendix Check Your Understanding and Challenge Questions Answer Key

Glossary of Key Terms