IP Fundamentals: What Everyone Needs to Know About Addressing and Routing

Description

• Copyright 1999
• Dimensions: 7" x 9-1/4"
• Pages: 512
• Edition: 1st

• Book
• ISBN-10: 0-13-975483-0
• ISBN-13: 978-0-13-975483-8

Finally, there's a non-theoretical, practical primer on all the basics of IP networking -- perfect for Web professionals, LAN managers, MIS managers, application developers, network administrators, and ISPs. This hands-on guide teaches all the fundamentals of IP addressing, routing, and troubleshooting -- with real-world exercises and examples throughout. The book contains broad coverage of the IP protocol itself; how IP operates over Ethernet, Token Ring, ATM, FDDI, and Frame Relay; the interplay between addressing and routing; OSPF; BGP-4 and its implications for edge customers; routing protocol interactions; techniques for minimizing and simplifying import/export; and more.

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Table of Contents

(NOTE: Most Chapters Conclude with References and Endnotes.)
Foreword.
Preface.

I. IP: ARCHITECTURE, ADDRESSING, AND ROUTING.

1. Introduction to the Internet Protocol.
What is IP? Communicating over LANs and WANs. IP Architecture Overview. Overview of the IP Header. What is Routing? Why is the Internet so Useful? Internet Applications.

2. Internet Addressing Conventions and Scaling Issues.
Introduction. Additional Practice with Classful IP Addressing.

3. Classical Subnetting.
What is Subnetting? Why is Subnetting Needed? Early Alternatives to Subnetting. Explicit Subnetting. Hierarchical Information Hiding. Extended- Network-Prefix. Subnet Addressing Plan Design. Considerations. Additional Practice with Subnetworks.

4. Generalized Subnetting.
Introduction to Variable Length Subnet Masks (VLSM) and Supernetting. VLSM. VLSM Design Considerations. EXAMPLE of Hierarchical Addressing. VLSM Example. VLSM Exercise. Manipulation of Subnets and Supernets.

5. Scalable Internet Address Management.
CIDR:Internet :: VLSM:Intranet. CIDR Practice Exercises. Endstation Implications for CIDR Deployment. New Solutions for Scaling the Internet Address Space.

II. LAN AND WAN SUBNETWORKS UNDER IP.

Subnetwork Functions.

IP Forwarding Procedure. 6. LAN Interconnection.

Introduction. Interconnection at OSI Layer 1. Interconnection at OSI Layer 2. Interconnection at OSI Layer 3.

7. Ethernet Technologies.
Introduction. Medium Access Control: CSMA/CD. Ethernet Frame Formats. Ethernet Media. Troubleshooting Ethernet.

8. IP Over Ethernet.
Introduction.

9. Token Ring and FDDI.
Introduction to Token-Passing Ring Technology. Token Ring Specifics. FDDI versus Token Ring. IP over Token Ring and FDDI.

10. The Point-to-Point Protocol.
Classification of Serial Lines. Dial-up versus Leased Lines. PPP Overview. Link Control Protocol (LCP). Authentication. Network Layer Control Protocol(s). Frame Format and IP Encapsulation.

11. Frame Relay.
Evolution of Wide-Area Cloud Technologies.

III. STANDARDS-BASED IP ROUTING PROTOCOLS.

12. Introduction to Routing.
The Relationship between Addressing and Routing. Role and Types of Routing Protocols.

13. RIP and OSPF.
Routing Information Protocol. Open Shortest Path First. General OSPF Guidelines. OSPF Deployment Considerations: Summary. RIP and OSPF Summary.

14. Interconnecting Dissimilar Unicast Routing Domains.
Overview of Interconnection Techniques. Simple: Aggregation. Complex: Explicit Import/Export of Routes. Compromise: Exchange LAN, Static Routes, Use Default.

Appendix A Use and Operation of Specific IP Troubleshooting Tools.
Introduction. ICMP is Inseparable from IP. Ping: An Application of ICMP. Traceroute. The Transport-Layer Echo Port.

Appendix B IEEE 802.1Q and 802.1p.
IEEE 802.1Q Tag Header. Priority Tagging. GARP.

Appendix C Dynamic Host Configuration Protocol (DHCP).
Some Advantages of DHCP. A Disadvantage of DHCP. DHCP Details.

Index.

Preface

PREFACE
The Internet Protocol has become the dominant networking protocol in use today, and its use continues to grow rapidly, with no end in sight. Thankfully, tools like the World-Wide Web (WWW) have put a friendlier face on the Internet, allowing its users to have a relatively painless experience. From the applications side (top-down), the WWW has made a huge difference, since the pre-WWW Internet was not really what one would call a consumer-oriented service.

However, the WWW has done nothing to improve the Internet's plumbing; if anything, it has increased the strain on the infrastructure (due to greatly increased numbers of users, and the very bursty nature of web traffic).Taking a bottom-up view, it is no easier today to define subnets, configure routers, etc. Even though certain tools now exist to aid in network design, the network mnagers still may not have the basic knowledge required to make the right design choices for their networks. Given that there is a continuous stream of new networks being attached to the Internet, there is a dramatic increase in the number of people who need to manage these new networks. In order to do a good job, new network managers, and all the network managers that preceded them, need a deeper level of understanding of IP than do users.

This book is meant for people who need to understand IP networking-related issues at a deep enough level to ensure that their networks are designed and operated properly. Ideally, the users will have a smooth experience, not realizing how much is really going on beneath the surface.

Part I examines IP addressing. How many hosts should be in some subnet? What is the broadcast address for that subnet? How should the addressing boundaries for a network be defined? Why must each subnetwork's IP prefix be unique (i.e., non-overlapping)? Network managers must be able to design addressing plans and overlay them on their networks' router topologies, configure routing protocols, and understand how the big picture is supposed to work well enough so that they can fix problems when they occur.

Also, it is worth noting that a well-designed network will be far more stable than one that is designed haphazardly (or not designed at all). Manipulating IP addresses is a key foundation skill, without which IP routing protocols and forwarding make little sense. A number of critical, basic skills related to manipulating IP addresses and subnet masks, which are not covered in detail in any one book or RFC, are explained here. I am not satisfied to simply state the rules and move on, however. Thoroughly worked-out examples are provided, and each chapter includes some exercises that should help to cement understanding of the concepts involved. Solutions to each exercise are provided, along with a rationale indicating how the answer was derived. Experienced network managers have learned these lessons through experience and trial-and-error. A goal of this book is to assist new network managers in getting up to speed on the real underlying addressing and routing issues. Mastery of Part I will ensure that no IP addressing-related question will perplex a network manager.

Part II concerns itself with two related issues. First, we need to understand the forwarding decision that each router uses to process a packet. Second, we need to see how IP packets are actually transmitted across the inter-router subnetwork "hops." Over its nearly thirty-year existence,(1) standards have defined how IP works over virtually every subnetwork technology. Luckily, it is not necessary to understand all of them. Only a few have become dominant, and the lessons learned from those generalize fairly well to the others. So, Part II covers how IP packets are carried over the most popular LAN(2) and WAN(3) subnetwork technologies.

Part II begins with a discussion of the IP forwarding decision process. The IP packet header includes a complete destination address, and routers use routing protocols to figure out which outgoing interface is "best," in the sense that it is in the direction of the destination (which will hopefully get the packet closer to its ultimate destination). Every intermediate router uses the same decision process. The differences arise in the subnetwork-specific details of each intermediate subnetwork "hop."

The IP layer is an abstraction, providing the Transport-layer protocols with subnetwork independence. Even though IP makes them all look similar to higher-layer protocols, each subnetwork technology really is quite different from the others.IP runs over an astounding number of physical media, from ArcNet to X.25. In this book, we examine the most common LAN (Ethernet, token ring, and FDDI) and WAN (PPP and Frame Relay) media. Once these have been understood, IP's operation over other media should be much easier to comprehend by generalizing the mechanisms learned here. Subnetwork technologies that are not mentioned here tend to be niche protocols that are not of general interest. (4)

Not only are addressing-related issues understood by a relatively small percentage of the IP users, but the interactions of addressing and routing are similarly poorly understood. In networks with well-coordinated addressing plans, it is possible to greatly minimize the routing table size at the core of the network. Part III contains an overview of routing technology, showing how the two most popular standards-based routing protocols, RIP and OSPF, operate. This part of the book really drives home the interrelationship between addressing and routing, especially in the chapter on interconnection of routing domains.

A well-designed addressing plan eases network troubleshooting because the addresses used within such a network are more meaningful, or may be related to a subnetwork addressing scheme (e.g., in a frame relay WAN). In such a network design, addresses that are "near" each other will have common prefixes, or leading bits, while "far away" numbers have quite different prefixes, making it easy to look at a number and know what part of the network it refers to. It is critically important that those deploying new networks be aware of addressing and routing issues. People sometimes tend to focus on the network applications and forget about the network itself, which, if well-designed will work smoothly for all applications.

The book concludes with a series of Appendices. Appendix A covers ping and traceroute, the two most common IP troubleshooting tools. Appendix B covers the Dynamic Host Configuration Protocol (DHCP), which is frequently used today to ease the administration of IP addresses within a network's defined subnetwork prefixes. Appendix C gives a broad overview of the new IEEE 802.1Q and 802.1p standards, which provide for standardized VLANs, multicast filtering at the MAC layer, class-of-service (CoS) prioritization, and other features. These new features seem poised to make a big impact on the way Ethernet-based networks will be deployed in the future. However, since they are still quite new, it did not seem appropriate to include them in the main chapters on Ethernet.

Acknowledgments
To my wife, Deb, I owe a huge acknowledgment for putting up with a second book right on the heels of the first. I am looking forward to having my spare time back to myself again. I am very grateful to the reviewers, who all offered valuable detailed comments that helped make this book better. Any lingering errors or unclear sections are obviously my responsibility. Once again, I must acknowledge my employer, 3Com. I am especially grateful to Jim Binder, who gave his permission for me to work on this project. Finally, Philippe Byrnes provided valuable moral support, and comic relief when necessary. I look forward to seeing his book(s) published this year.

Many thanks to the team at Prentice Hall PTR, especially Mary Franz, Noreen Regina, and Vince Janoski. Without Mary's constant gentle pressure, this book would not exist. Her patience was considerable, especially considering that this ended up being several months late due to a combination of medical problems and an over-aggressive schedule. Noreen did a great job of making sure that the reviewers' comments made it to me in a timely fashion, and did a great job as "virtual Mary" when necessary. :-) Finally, and very important, Vince Janoski has been doing a great job of managing the whole production process. Once the first draft was done, he took over. Turning 555 pages of double-spaced text into a finished, polished book takes a lot of steps, most of which I am barely aware of.

Vince is making it all happen, and based on the results so far, I'm looking forward to seeing the finished product this Spring!

Finally, I feel that I should thank Dr. Kendra Peterson and Dr. John R. Adler of the Stanford University Medical Center.

Endnotes
1. IP was first deployed in the Internet in 1981.
2. Ethernet, token ring, and FDDI.
3. PPP and Frame Relay.
4. Note that IP over ATM is not specifically covered here in this book for several reasons.

First, when used in PVC mode, ATM is somewhat similar to Frame Relay. Second, IP over ATM is a very broad and complex subject to which whole books have been devoted. Third, IP over ATM LAN Emulation is just the same as IP over Ethernet or token ring, as far as IP is concerned.

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