Internet Routing Architectures, Second Edition does not really require any introduction. It is a smash hit and one of the best-selling books written in the history of Cisco press.

Internet Routing Architectures, Second Edition is written by Sam Halabi and Danny McPherson. Sam Halabi is extremely proficient in complex routing protocols and has specialized in large scale IP network designing. He also served on the board of directors of the Optical Internetworking Forum (OIF) and the MPLS forum. This book expands on the smash success of the first edition, with new updates on BGP and advanced perspectives on internetworking routing architectures.

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The second edition uses a practical, example-oriented approach to provide solutions for ISP connectivity issues. It is very hard to write technical information in an accessible manner—if the description is worded with too much technical detail then it loses its meaning—but I must congratulate the author here in providing precise and detailed technical information without obscure terms. This book introduces more complex concepts gradually and in the context of practical scenarios whenever possible.

Each chapter ends with frequently asked subjective questions and answers which provide the best way to judge your level of understanding along with references for further studies. Concepts are presented in a very matter of fact way, diagrams are clear and correctly annotated.

The book is organized into four parts:

  • Part I: The Contemporary Internet (Chapter 1 – 3)
  • Part II: Routing Protocol Basics (Chapter 4 – 5)
  • Part III: Effective Internet Routing Designs (Chapter 6 – 10)
  • Part IV: Internet Routing Device Configuration (Chapter 11 – 12)
  • Part V: Appendixes

Part I: The Contemporary Internet

Chapter 1 covers a brief history of early Internet communication technologies and the evolution of the Internet in the last few decades. This chapter provides descriptions of early technologies used to develop Internet communication, and covers almost all early advancements like the ARPANET and NSFNET with straightforward language and graphical representations.

Chapter 2 provides pure theoretical concepts of ISP services and characterization of ISPs on the basis of physical access methods including Frame Relay/ATM Internet access, dialup services, DSL, cable modems and security options. This chapter also covers the criteria for evaluating ISPs on the basis of their network topology and traffic exchange agreements.

Chapter 3 covers some of the theoretical fundamentals of IP addressing/subnetting and allocation techniques. This chapter assumes that you have enough knowledge of VLSM and subnet analysis. I don’t think you will find anything special in this chapter to learn.

Part II: Routing Protocol Basics

Chapter 4 starts with a consideration of the routing protocols responsible for routing within an autonomous system. This chapter provides an overview of interior gateway protocols as a first step before starting the journey to exterior gateway protocols such as BGP.

After the first four chapters, you will finally learn about BGP. Chapter 5 is designed to explore some basic BGP concepts like how it works, BGP neighbor states and BGP path attributes, but I like the representation of finite state machine (Fig. 5.8) the most in this chapter. It is well drawn and easy to understand. This chapter covers basic but useful information regarding BGP in a very descriptive way.

Part III: Effective Internet Routing Designs

Usually we buy this book mainly to learn BGP. This really starts in PART III, which examines BGP in a practical and functional approach with real time examples and scenarios to illustrate its design concepts.

Chapter 6 examines how to control BGP routes with the collection of BGP’s path attributes as per network requirements. This chapter explores how route filtering can be done on a prefix or a path level using BGP with a hands-on approach to understand the fundamentals working behind the routing policies.

After completing Chapter 6, you will be able to use BGP route filtering/path attribute manipulation to specified internetworking topologies. Chapter 7 will provide a great help in understanding and designing goals like redundancy, symmetry and load balancing in BGP, which are of varying importance depending on the requirements of a network. This chapter is well designed for learning single-homing, multi-homing with same/different providers’ network scenarios.

Chapter 8 examines how traffic flows inside an Autonomous System before it moves out. This chapter also discusses the use of policy routing to control routing behaviours on the basis of source rather than destination.

Chapter 9 introduces concepts and the techniques to control large scale autonomous systems. It is one the best chapters of the book, as it offers methods of managing full mesh requirements in a large scale AS. Here you can learn “How to deal with split horizon issues in BGP?” with world class industrial examples and content which will help you learn Route-Reflector, Confederations quickly. This chapter also deals with loop avoidance techniques with explanations on concepts of originator-id and cluster-id.

Chapter 10 examines the causes of route instabilities on the Internet and how to stop them. This chapter also introduces techniques that minimize the dampening effect, and after this chapter you will be able to refresh BGP routes without having to reset/flap a BGP connection.

Part IV: Internet Routing Device Configuration

The best part of this book is still to come: all technologies explained in the first ten chapters are represented here with a unique learning and real implementation approach. I promise you, after completing Chapters 11-12, you will definitely say, “Yes, this is exactly what i was looking for.” These two chapters cover almost all of the most important BGP concepts including building peering, route filtering and attribute manipulation, peer groups, aggregation, route-reflectors, confederations and route dampening, etc. The command output is also easy to follow.

Part V: Appendixes

Finally, Part 5 is dedicated to appendixes for BGP command references, further studies and a short note on MPBGP.

Best chapters in my opinion: Although all chapters are well designed and provide excellent study resources that compete with real time industrial BGP concepts, I must recommend chapters 6, 9, 10, 11 and 12. I personally liked Chapters 11 and 12 the most because both explore BGP concepts with a large variety of command based implementations. I hope you will enjoy these chapters as well.

Over all I found “Internet Routing Architectures, Second Edition” as one of the best study guides to date for examining BGP concepts in very disciplined manner. At the same time, it delivers comprehensive examples which are useful for real time implementation and troubleshooting. For that I would like to thank the author Sam Halabi; this book really deserves 5 pings out of 5.

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