Product Description

Offers an expert's insight into how and why networks operate as they do. Describes all of the major networking algorithms and protocols in use today in clear and concise terms, while exploring the engineering trade-offs that the different approaches represent. DLC: Routers (Computer networks).

Product Details

• Amazon Sales Rank: #84648 in Books
• Published on: 1999-09-24
• Original language: English
• Number of items: 1
• Binding: Hardcover
• 560 pages

Amazon.com Review
This latest release of Interconnections is a competent update of a networking classic. Radia Perlman explains hundreds of details about getting computers--and computer networks--to talk to one another smoothly, accurately, and efficiently. Perlman, inventor of the spanning-tree bridging algorithm, covers the Open Systems Interconnect (OSI) reference model, bridges, switches, hubs, Virtual Local Area Networks (VLANs), plus connection-based and connectionless networks. She also does a great job of explaining the underpinnings of internetworking protocols, including packet format, addressing, routing (both generically and in terms of RIP, RTMP, OSPF, and other protocols), and security. There's plenty of IPv6 information here, mostly from a theoretical vantage point.

The best parts of Perlman's approach to her subject are the little thought experiments that explain why various aspects of internetworking behave the way they do. For example, Perlman talks about Maximum Transmission Unit (MTU) discovery by presenting four different hypotheses for figuring out MTU. For each possible solution, she discusses strengths, weaknesses, and real-life considerations. She applies this method to dozens of other problems and phenomena, making Interconnections a very close approximation of learning by experiment. --David Wall

Topics covered: Open Systems Interconnect (OSI) reference model, bridges, switches, hubs, Virtual Local Area Networks (VLANs), and internetworking protocols.

From the Inside Flap

Interconnections, Second Edition is about what goes on inside the boxes that move data around the Internet. These boxes are variously called bridges, routers, switches, and hubs. The book also describes the devices that connect to the network.

There is considerable confusion in this area. Most of the terminology is ill defined and is used in conflicting ways. The terminology and the specifications tend to be daunting. Some knowledge is spread among many different documents; much is unwritten folk wisdom. Adding to the confusion is dogma. Beliefs are accepted as truth, and questioning any of the dogma is often greeted with hostility. But good engineering demands that we understand what we're doing and why, keep an open mind, and learn from experience.

In Interconnections, Second Edition, instead of diving right into the details of one protocol, I first focus on the problems to be solved. I examine various solutions to each of these problems and discuss the engineering trade-offs involved. Then I look at a variety of solutions that have been deployed and compare the approaches. I give technical arguments for any opinions, and if you think I have missed any arguments I welcome email discussion. My email address is at the back of the book, which I hope you will find after having read the book cover to cover.

In the first edition, my intention was to help people understand the problems and the general types of solutions, assuming that they would read the specifications to get the details of specific protocols. But people used the book as a reference in addition to using it to understand the issues. So in this edition I have documented many more of the protocols in detail.

I believe that to understand something deeply you need to compare it to something else. The first edition was "minimalist" in that I always used only two examples: two types of bridges, bridges versus routers, connection-oriented versus connectionless network layer protocols, and two examples of connectionless protocols (CLNP and IP). In this edition I add a lot more examples, including ATM, IPv6, IPX, AppleTalk, and DECnet. I did this in part because these protocols exist, and it is hard to get information about them. But mostly I did it because the protocols embody interesting ideas that should not be lost. When we design new protocols, we should learn from previous ideas, both good and bad. Also, it takes very little additional effort, after the problem is described generically, to describe several examples. Roadmap to the Book

The first four chapters are not significantly different from their counterparts in the first edition, but the rest of the book has been largely rewritten. Chapters 1 through 4 cover general networking concepts, data link issues such as addressing and multiplexing, transparent bridges and the spanning tree algorithm, and source routing bridges. Chapter 5 is completely new and explains how the notion of a switch evolved into a rediscovery of the bridge. It also covers VLANs and fast Ethernet.

The remainder of the book concentrates on layer 3 (the network layer). Chapter 6 gives an overview of the network layer. Chapter 7 covers connection-oriented networks, including ATM and X.25. Chapter 8 discusses the issues in a generic connectionless network layer. Chapter 9 covers layer 3 addressing generically and gives a detailed comparison of IP, IPv6, CLNP, DECnet, AppleTalk, and IPX. Chapter 10 covers the information that should appear in a network layer header and contrasts the headers of several protocols.

Chapter 11 covers autoconfiguration and neighbor discovery, including protocols such as ARP and DHCP. Chapter 12 covers routing algorithms generically.

Chapter 13 discusses the problem of doing longest-prefix matching, which is required in order to forward IP packets quickly. Chapter 14 discusses the specifics of various routing protocols including RIP, IS-IS, OSPF, PNNI, NLSP, and BGP. Chapter 15 covers network layer multicast. Chapter 16 explains how to design a network that is invulnerable to sabotage, an idea whose time may come.

The final two chapters summarize the book, and I hope they will be mostly light and entertaining reading. Chapter 17 probes the mystery of what, if anything, distinguishes a router from a bridge. Chapter 18 attempts to capture folk wisdom about how to design a protocol.

Finally, there is an extensive glossary. I try to define terms when I first use them, but if I ever fail to do that, you will probably find them in the glossary. Acknowledgments

Writing this section is scary because I am afraid I will leave people out. I'd like to thank the people who reviewed all or part of the book: Peter Memishian, Paul Koning, Tony Lauck, Craig Partridge, Dan Pitt, Brian Kernighan, Paul Bottorff, Joel Halpern, Charlie Kaufman, Mike Speciner, Andy Tanenbaum, Phil Rosenzweig, Dan Senie, William Welch, Craig Labovitz, Chase Bailey, George Varghese, and Suchi Raman. Other people who have been helpful by answering questions are Ariel Hendel, Rich Kubota, Stuart Cheshire, Tom Maufer, Steve Deering, and John Moy. The first time I sent an email question in the middle of the night (when I did most of my work on this book) to Craig Partridge, the co-series editor for this book, the beep indicating incoming mail happened so immediately that I assumed it was an automatic mail responder informing me he was on vacation. But it was an answer to my question. I assume he doesn't have an automatic mail responder so clever that it can answer technical questions, so I thank him for being so prompt and available. Brian Kernighan, the other series editor, also had detailed and helpful comments on the entire book.

The people at Addison-Wesley have been amazingly patient with me for the many years in which I've been working on this edition. I'm not sure they had any alternative besides patience, but it was nice that they believed I'd finish even when I wasn't so sure. So thank you to Mary Hart, Karen Gettman, Jacquelyn Doucette, and Jason Jones. And I'd also like to thank my copy editor, Betsy Hardinger. She of all people will have read every word of the book, while maintaining the concentration to note inconsistencies and ways of removing excess words here and there. I know it's her job, but I'm still impressed.

Mike Speciner helped me figure out the mysteries of Framemaker. Ray Perlner made sure that I maintained some humor in the book and watched over my shoulder while I typed the last chapter to see that I had enough funny bad real-life protocols. Dawn Perlner has been terrifically supportive, convincing her friends and even strangers in bookstores to buy my books. She used to be my child. Now she's a wonderful friend.

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From the Back Cover
Radia Perlman's Interconnections is recognized as a leading text on networking theory and practice. It provides authoritative and comprehensive information on general networking concepts, routing algorithms and protocols, addressing, and the mechanics of bridges, routers, switches, and hubs. This Second Edition is expanded and updated to cover the newest developments in the field, including advances in switching and bridge technology, VLANs, Fast Ethernet, DHCP, ATM, and IPv6. Additional new topics include IPX, AppleTalk, and DECnet. You will gain a deeper understanding of the range of solutions possible and find valuable information on protocols for which documentation is not readily available elsewhere.

Written by the inventor of many of the algorithms that make switching and routing robust and efficient, Interconnections, Second Edition offers an expert's insight into how and why networks operate as they do. Perlman describes all of the major networking algorithms and protocols in use today in clear and concise terms, while exploring the engineering trade-offs that the different approaches represent.

The book contains extensive coverage of such topics as:

Customer Reviews

A highly technical but easy to read book on networking
If you are looking for a highly readable, but technical book on computer networking, this one is great. It contains some material on hardware, but it is mostly about algorithms and protocols. The author is one of the world's most respected authorities on the subject, having invented some of the key protocols and algorithms herself. Unlike many experts, however, she is able to explain the material in a straightforward way, making it accessible to anyone with a good technical background and an interest in the subject. The final chapter, on protocol design folklore, is unmatched anywhere. It gives tremendous insight into how to design a protocol and what can go wrong if you are not careful. This chapter is well worth the price of the book alone and"must" reading for anyone actually planning to design a protocol.

Foundational Reading!
There are moments when this book reads like a detective story with drama, plot, and humor but even when Radia Perlman is simply working through the details of internetworking protocols the writing is clear and crisp. The chapters are well organized and diagrams are used very effectively to make even dense concepts accessible.

What I liked best about Interconnections was being consistently able to understand what the author was saying. While an electrical engineer might get a little more out of her discussions than I did I never felt locked out because my undergraduate education was in the liberal arts.

The material she presents is not always easy. In fact, Radia notes, "Anyone who isn't confused about when routers become EGP neighbors and what the rules are for configuring routers to initiate being EGP neighbors does not understand EGP" (p. 428). And yet the reader who is willing to concentrate and follow her lead can understand everything covered.

Even though this is a marvelously written book it is not for everyone. I would hesitate to recommend it to a network technician wanting to understand networks more fully. While I think every computer science student should spend two semesters working through these 18 chapters, memorizing the Glossary, and discussing the suggested homework problems the book is overkill for the ordinary MCSE candidate wanting to master Networking Essentials for a Microsoft certification exam. Interconnections is foundational reading for those who would design protocols or vendor equipment designed to interoperate with protocols but it is a bit much for someone who just wants to know which port to plug the cable into.

While Interconnections is not for everyone, I think it is essential reading for anyone who makes purchase decisions in an enterprise network. Without a firm understanding of bridges, routers, switches, and internetworking protocols they become far too vulnerable to sales techniques. And Interconnections is an essential reference for the Network Analyst. Radia notes that in the first edition of her book she assumed people would read the RFCs to get details that she omitted but they didn't. As someone who has spent some time trying to digest RFCs I am grateful that she bulked up the Second Edition with what she thought people needed to know. I can figure out what she writes but frequently feel I have wasted the effort when trying to get what I need out of the RFCs. Interconnections is a convenient one stop resource for researching packet headers and the various control messages that analyzer software may capture while sniffing a network to identify problems.

Interconnections, Second Edition is 150 pages larger than the First Edition published in 1992. Radia has reorganized, rewrote, added examples, included new protocols and more fully documented details to make it a better reference book. The Glossary was expanded from 4 pages to 10 but that was not enough. Radia does a good job of defining terms in the body of the book the first time they are used but not again in later chapters. When they are not in the Glossary it leaves the reader having to page around looking for the first definition. And the Index shrank from 15 pages to 5 between the First and Second Editions and thus became less useful for finding obscure terms.

Radia Perlman proposes that, "Before we design a solution, it's often useful to define the problem to be solved" (p. 505). To explain a protocol in the book she typically presents a list of problems and then walks through adding features to an algorithm to solve one or more of them. She discusses how adding one feature may create new problems. It is fascinating to do this exercise in relationship to real world protocols that are used everyday and to realize that some problems could be relieved if standards bodies could more readily agree. And that brings up one of the most enjoyable aspects of Interconnections, Radia sharing anecdotes and criticisms from years of participating on the Internet Engineering Task Force.

One take home message for me from reading Interconnections is that it is always best to keep it simple. Added complexity rarely pays off in anything but trouble. Radia opined, "I think people should be grateful if their packets get there at all" (p.202) rather than jumping through a lot of hoops to insure optimal routing. This is a good message for those who build internetworking protocols as well as those who just plug cables into ports.

great technical introduction, indispensible reference
The 2nd edition of Interconnections is every bit as good as the exceptional 1st edition, but is expanded by about 50%. Still present is Dr. Perlman's clear, concise coverage of the theory and practice of the fundamental network building blocks: bridges, routers, and "switches" (including token ring source-route bridging). Also still included is a brief synopsis of her dissertation on sabotage-proof network protocols, an idea whose time has definitely come. The coverage on specifics of network protocols is significantly expanded, particularly TCP/IP (v4 and v6), IPX/SPX, DECnet, and AppleTalk. Coverage of specifics of routing algorithms, such as RIP and OSPF, is also expanded, now even including multicast extensions. New material has been added that lays bare the details of fast ethernet, gigabit ethernet, ATM ("classical" IP-over-ATM and LANE), and NAT/NAPT. I highly recommend the 2nd edition to anyone wanting to increase their technical understanding of networking, no matter what your knowledge/experience level, and as a nonpartisan technical reference for networking professionals.