Cisco Press
201 W 103rd Street
Indianapolis, IN 46290
Cisco Press

CCNP Self-Study

CCNP BSCI Exam
Certification Guide

Clare Gough

chpt_01.book Page i Thursday, January 9, 2003 4:32 PM

ii

CCNP BSCI Exam Certification Guide

Clare Gough
Copyright © 2003 Cisco Systems, Inc.
Published by:
Cisco Press
201 West 103rd Street
Indianapolis, IN 46290 USA
All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or
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mission from the publisher, except for the inclusion of brief quotations in a review.
Printed in the United States of America 1 2 3 4 5 6 7 8 9 0
First Printing January 2003
Library of Congress Cataloging-in-Publication Number: 20-02115641


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Steve Wisniewski
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chpt_01.book Page iii Thursday, January 9, 2003 4:32 PM


skiing and hill scrambling.

Tim Sammut

, CCIE No. 6642, is a senior network engineer for ExtraTeam, a Cisco partner in San Francisco, Cali-
fornia. Tim has served in key project roles involving technologies from LAN switching to security to SNA integra-
tion and has helped many organizations, ranging from 100 to 130,000 users, make the most of their network
investment. Tim also holds the CISSP, CCIE Security, MCNE, and MCSE certifications.

Brent Stewart

is a Cisco instructor for Global Knowledge. As a Global Knowledge employee, he participated in the
development of ICND, BSCI, BCMSN, BCRAN, and CIT for Internet-based delivery and served as SME (Subject
Matter Expert) for the CD-based ICND and CIT titles. He is currently participating in the BSCI 2.0 update as the lab
development engineer. Prior to working for Global Knowledge, Brent owned an ISP and worked as an IT consultant.
Brent holds the CCNP and CCDP certifications.

Martin Walshaw

, CCIE No. 5629, CCNP, CCDP, is a systems engineer working for Cisco Systems in the enterprise
line of business in South Africa. His areas of specialty are multiservice (voice and video) as well as security, which
keeps him busy both night and day. During the last 12 years or so, Martin has dabbled in many aspects of the IT
industry, ranging from programming in RPG III and Cobol to PC sales. When Martin is not working, he likes to
spend all his available time with his wife, Val, and his son, Joshua. Without their patience, understanding, and sup-
port, projects such as this would not be possible.

Steve Wisniewski

is CCNP certified and has a master of science degree from Stevens Institute of Technology in
telecom management. Steve works for Lehman Brothers as a senior implementation specialist implementing Cisco

larly like to thank Jorge Aragon and Steve Wisniewski who went the extra mile by testing configurations and
producing output screens.
I would also like to thank Wendell Odom, who led me into the art of book writing and has ever generously shared his
expertise.
Of course, I am immensely grateful to my husband, David, for his support, in spite of the long hours demanded by
this book, and to our small son, Jack, for making me laugh and see the joy of life.

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vii

Contents at a Glance

Chapter 1

Cisco Certifications, the BSCI Exam, and This Book’s Features 3

Chapter 2

Managing Scalable Network Growth 27

Chapter 3

IP Addressing 83

Chapter 4

IP Routing Principles 157

Chapter 5


Appendix A

Answers to Quiz Questions 771

Appendix B

Sample Configurations 843

Appendix C

Glossary 859

Index

903

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Contents

Chapter 1

Cisco Certifications, the BSCI Exam, and This Book’s Features 3

Goals of This Book 4
This Book’s Intended Audience 5
Prerequisites to Reading the Book 5


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ix

Responsiveness 33
Efficiency 34
Adaptability/Serviceability 34
Accessibility/Security 34
Factors That Increase Network Traffic 35
Identifying the Problems Created by Network Congestion 35
Traffic Analysis and Network Design 35
Problems Created by Network Congestion 36
Excessive Traffic 36
Physical Problems of Ethernet 36
Dropped Packets 37
Retransmission of Packets 37
Incomplete Routing Tables 37
Incomplete Server Lists 38
The Spanning-Tree Protocol Breaks 38
Runaway Congestion 39
Symptoms of Congestion 39
Applications Time Out 40
Clients Cannot Connect to Network Resources 40
Network Death Results 40
Creating a Network That Meets the Key Requirements 40
Cisco’s Hierarchical Design 41
Why Scaling Reduces Congestion 41
How Hierarchical Is Hierarchical? 41
The Functions of Each Layer 41

CPU Considerations and Additional Methods for Controlling Network Traffic 57
Fast, Autonomous, and Silicon Switching 58
Cisco Express Forwarding 58
Placement of Client/Server 59
Design Principles of a Client/Server Network 59
IP Helper Address 59
Configuration of IP Helper Address 60
Enhanced Interior Gateway Routing Protocol 60
Tunneling into IP 61
Configuration of Tunneling into IP 63
Conclusion 64
Foundation Summary 65
Chapter Glossary 68
Q & A 69
Scenarios 74
Scenario 2-1 74
Scenario 2-2 76
Scenario 2-3 76
Scenario Answers 77
Scenario 2-1 Answers 77
Scenario 2-2 Answers 78
Scenario 2-3 Answers 79

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Chapter 3

IP Addressing 83

Problems with IP Addressing and the Internet 99
CIDR as a Solution 99
Summary of CIDR 100
An Example of the Use of CIDR 100
An Example of CIDR in Use in the Case Study 101
Advantages of Prefix Routing/CIDR 101
Variable-Length Subnet Masks 103
An Example of VLSM 103
Routing Protocols That Support VLSM 103
Rules for VLSM 104
The Advantages of Using VLSM 104

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Case Study: Addressing the Network 105
Bit Allocation, the Subnet Rule, and VLSM 107
Allocating VLSM Addresses 107
Summarization 109
The Advantages of Summarization 112
Reducing the Size of the Routing Table 112
Simplification 112
Hiding Network Changes 112
Network Growth 112
Other Solutions to Address Exhaustion 113
Configuring Summarization 113
Automatic Summarization 113
Manual Summarization 113
Discontiguous Networks 114

Scenario 3-2 Answers 150
Scenario 3-3 Answers 153

Chapter 4

IP Routing Principles 157

How to Best Use This Chapter 157
“Do I Know This Already?” Quiz 158
Foundation Topics 162
Introduction: What Is a Routing Protocol? 162
Case Study 162
What Is a Routing Protocol? 162
The Definition of a Routing Protocol 163
The Purpose of a Routing Protocol 163
How the Routing Protocol Works 163
Routing and Routed 163
The Network Field 164
The Purpose of the Network Field 164
How the Network Field Is Used 165
The Outgoing Interface Field 165
The Purpose of the Outgoing Interface Field 165
The Metric Field 165
The Next Hop Field 166
The Purpose of the Next Hop Field 166
The show ip route Command 167
How the Routing Table Is Kept Current and Correct 168
Switching Versus Routing 169
The Routing Function 169
The Switching Function 170

Foundation Summary 186
Chapter Glossary 189
Q & A 193
Scenarios 198
Scenario 4-1 198
Scenario 4-2 200
Scenario Answers 202
Scenario 4-1 Answers 202
Scenario 4-2 Answers 203

Chapter 5

Using OSPF in a Single Area 205

How to Best Use This Chapter 205
“Do I Know This Already?” Quiz 206
Foundation Topics 211
Introduction: What Is OSPF? 211
Case Study 211
OSPF Terminology 212
OSPF Neighbors 214
OSPF Network Topologies 214
The Hello Packet 216
Adjacent OSPF Neighbors 217
Advantages of Having Neighbors 218
The Designated Router 218

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Configuring OSPF over an NBMA Topology 242
Configuring OSPF in NBMA Mode 242
Configuring OSPF in Point-to-Multipoint Mode 244
Design Points for the Point-to-Multipoint Mode 244
Configuring OSPF in Broadcast Mode 244
Configuring OSPF in Point-to-Point Mode on a Frame Relay Subinterface 245
Checking the Configuration of OSPF on a Single Router 246
The show ip ospf Command 247
The show ip ospf database Command 248
The show ip ospf interface Command 250
The show ip ospf neighbor Command 252
The show ip protocols Command 255
The show ip route Command 257

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Conclusion 257
Foundation Summary 258
Routing Table 261
Learning a New Route 261
Command Summaries 263
Chapter Glossary 264
Q & A 266
Scenarios 271
Scenario 5-1 271
Scenario 5-2 272
Scenario 5-3 272
Scenario Answers 274


Design Considerations in Multiple Area OSPF 299
Summarization 300
The Virtual Link 300
OSPF over an NBMA Network 301
Configuring OSPF on a Multiarea Network 302
Configuration Commands for a Multiarea OSPF Network 302
The network Command 302
The OSPF area range Command for an ABR 304
The OSPF Summarization Command for an ASBR 305
The OSPF Command for a Stub Area 307
The OSPF Command for a Totally Stubby Area 308
The OSPF Command for the Cost of a Default Route Propagated
into the Area 310
Configuring a Virtual Link 311
A Working Configuration of OSPF on a Multiarea Network 314
Checking the Configuration of OSPF on a Multiarea Network 315
The show ip ospf border-routers Command 316
The show ip ospf virtual-links Command 317
Conclusion 318
Foundation Summary 319
OSPF Routers 319
Link-State Advertisements 320
Routing Table Codes 320
Command Summaries 321
Q & A 322
Scenarios 327
Scenario 6-1 327
Scenario 6-2 329
Scenario 6-3 331

Basic Principles of Area Routing 358
Integrated IS-IS Networks and Interfaces 360
Establishing Adjacencies on a Point-to-Point Link 362
Establishing Adjacencies on a Broadcast Link 362
Establishing Adjacencies on a Nonbroadcast Multiaccess (NBMA) Link 363
Network Layer Protocols Used in Integrated IS-IS 363
The Format of the Hello Packet 365
The Format of the LSP 367
The Format of the SNP 368
TLVs 369
Integrated IS-IS Operation 371
The Update Process 372
Sending and Receiving an LSP 372
Determining Whether the LSP in the Database Is Valid 374
The Decision Process 375
Metrics or Cost 376
The Forwarding Process 377
The Receive Process 377
Integrated IS-IS Design Considerations 377
Area Design of Integrated IS-IS Routers 377
Route Summarization 379
Integrated IS-IS NBMA Modeling Solutions in a Switched WAN Network 379

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Configuring Integrated IS-IS 380
Changing the Router from Level 1-2 381
Configuring Summarization 384

EIGRP Defined 429
Operation of EIGRP 430
How EIGRP Works 431
The Hello Protocol 434
Becoming a Neighbor 434

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The Neighbor Table 434
The Topology Table 436
EIGRP Metrics 438
The DUAL Finite-State Machine 439
Updating the Routing Table in Passive Mode with DUAL 440
Updating the Routing Table in Active Mode with DUAL 441
Choosing a Successor 442
Scaling EIGRP 449
Reasons for a Poorly Scaled EIGRP Network 449
Symptoms of a Poorly Scaled EIGRP Network 449
Solutions to EIGRP Scaling Issues 450
Design Issues Particular to EIGRP 450
The Routing Table 451
Configuring EIGRP 451
The Required Commands for Configuring EIGRP 452
The Optional Commands for Configuring EIGRP 454
Summarization with EIGRP 454
Load Balancing in EIGRP 454
Bandwidth Control 456
EIGRP Defaults in Bandwidth Utilization 456

“Do I Know This Already?” Quiz 484
Foundation Topics 488
Introduction: BGP-4 and Communicating with other Autonomous Systems 488
Case Study 488
BGP-4 Operation 489
An Autonomous System Defined 490
Characteristics of BGP-4 491
Overview of the BGP-4 Operation 491
Message Types 492
Synchronization 494
Benefits of the Synchronization Rule 494
CIDR and Route Aggregation 496
BGP-4 Policy-Based Routing 497
Rules of Policy Routing 497
Disadvantages of Policy Routing 499
BGP-4 Attributes 500
The Next-Hop Attribute and a Broadcast Multiaccess Network 503
The Next-Hop Attribute and a Nonbroadcast Multiaccess Network 505
Route Selection Process 505
Basic Configuration Commands to Connect to Another Autonomous System 507
Starting the Routing Process 508
Defining the Networks to Be Advertised 508
Identifying Neighbors and Defining Peer Groups 508
Forcing the Next-Hop Address 508
Disabling Synchronization 509
Aggregating Routes 509
Managing and Verifying the BGP-4 Configuration 510
When to Use BGP-4 511
When Not to Use BGP-4 511
Alternative Methods of Connecting to an ISP 512

Why Is a Fully Meshed Network a Problem? 546
Route Reflectors: The Solution to a Fully Meshed IBGP-4 Network 547
Designs That Avoid a Fully Meshed IBGP-4 Network 548
How Route Reflectors Operate 549
Controlling BGP-4 Traffic 556
How Prefix Lists Work 557
How Prefix Lists Are Processed 558
How to Configure a BGP-4 Prefix List 558
Creating a Prefix List 558
Prefix List Examples 559
Verifying the Prefix List Configuration 559
Redundant Connections into the Internet—Multihoming 560
Multiple Connections into the Internet 561
Receiving Routing Information from the Internet 561
Determining the BGP-4 Path by Tuning the Attributes 564
Commands to Tune BGP-4—Using the Local Preference and Weight Attributes 564
Verifying the Configuration of Attributes 567
Redistribution Between the IGP and BGP-4 570
Advertising Routes from an IGP into BGP-4 571
Advertising Routes from a BGP-4 into an IGP 571
Do ISPs Need to Redistribute Paths from BGP-4 into the IGP? 571
Redistribution from BGP-4 into an IGP in an Organizational Network 572

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Conclusion 573
Foundation Summary 574
Route Reflectors 575

Problems of Configuring Multiple Routing Protocols 607
Path Selection Within a Routing Protocol 608
Path Selection Between Routing Protocols 610
Avoiding Routing Loops When Redistributing 612
Redistribution and Problems with Network Convergence 613

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Configuring Redistribution 614
Generic Steps Required for Redistribution 614
Redistribution Configuration Syntax 615
The Default or Seed Metric 617
When to Configure the Administrative Distance 619
The Passive Interface 621
Static Routes 621
Default Routes 623
Controlling Routing Updates with Filtering 625
Redistribution Examples 627
Redistribution Example 1 628
Redistribution Example 2 629
Redistribution Example 3 632
Policy-Based Routing Using Route Maps 633
Uses for Route Maps 634
Characteristics of Route Maps 634
The Route Map Command Syntax 635
Policy-Based Routing Using Route Maps 636
Characteristics of Policy Routing 637
The Benefits of Policy Based Routing 637

Scenario 11-1 Answers 660
Scenario 11-2 Answers 662

Chapter 12

Scenarios for Final Preparation 665

Further Study for Final Preparation 665
How to Best Use This Chapter 666
Scenarios 667
Scenario 12-1 667
Scenario 12-2 668
Scenario 12-3 669
Scenario Answers 671
Scenario 12-1 Answers 671
Scenario 12-2 Answers 673
Scenario 12-3 Answers 675
Three-Part Scenarios 678
Scenario 12-4 678
Scenario 12-4, Part A—Planning 678
Solutions to Scenario 12-4, Part A—Planning 683
Scenario 12-4, Part B—Configuration 687
Solutions to Scenario 12-4, Part B—Configuration 688
Scenario 12-4 Part C—Verification and Questions 689
Solutions to Scenario 12-4, Part C—Verification and Questions 720
Scenario 12-5 724
Scenario 12-5, Part A—Planning 724
Solutions to Scenario 12-5, Part A—Planning 726
Alternative Methods of Transition to Another Routing Protocol 726
Transitioning to EIGRP from the Outer Edges of the Network 727