Computer Networks and Internets is appropriate for all introductory-to-intermediate courses in computer networking, the Internet, or Internet applications; readers need no background in networking, operating systems, or advanced mathematics.
Leading networking authority Douglas Comer presents a wide-ranging, self-contained tour of the concepts, principles, and technologies that enable today’s Internet to support applications ranging from web browsing to telephony and multimedia. This Fifth Edition has been thoroughly reorganized, revised, and updated: it includes extensive new coverage of topics ranging from wireless protocols to network performance, while reducing or eliminating coverage of older protocols and technologies. Comer begins by illuminating the applications and facilities offered by today’s Internet. Next, he systematically introduces the underlying network technologies and protocols that make them possible: low-level data communications; packet switching, LAN, and WAN technologies; and Internet protocols such as TCP, IP, UDP, and IPv6. With these concepts and technologies established, he introduces several of the most important contemporary issues faced by network implementers and managers, including quality of service, Internet telephony, multimedia, network security, and network management. Comer has carefully designed this book to support both top-down and bottom-up teaching approaches. Students need no background in operating systems, and no sophisticated math: Comer relies throughout on figures, drawings, examples, and analogies, not mathematical proofs.
This textbook for a two-semester undergraduate course in networking is divided into four sections--low-level transmission, packet switching, internetworking, and network applications. The new edition adds three chapters on tools students can use to explore the Internet, long-distance digital connection technologies, and RPC and middleware. The CD-ROM includes photographs of network wiring. Annotation c. by Book News, Inc., Portland, Or.
Two Takes on Computer Networks
Computer Networks and Internets and Computer Networks, 3rd Edition cover much of the same ground: discussing networking with primary emphasis on TCP/IP. They're both hardcover books, intended to be used as textbooks for course material. Both authors are professors (Comer at Purdue, Tanenbaum at Vrije Universiteit in Amersterdam). I've read many books by both authors of the years (Tanenbaum developed a teaching Unix-like system called Minix, Comer developed another system called Xinu [Xinu is not Unix]).
Comer's book has 32 chapters broken up into 4 sections:
Tanenbaum's book is broken up roughly the same way, with each chapter being very large and equating to Comer's sections:
The Physical Layer
The Datalink Layer
The Medium Access Sublayer
The Network Layer
The Transport Layer
The Application Layer
Comer in the preface tells who the book is for: a one or two semester undergraduate course where the goal is breadth, not depth. But most student's objective is to learn how the internet works: this entails an understanding of how networks work, but on a somewhat superficial level.
Comer re-emphasizes his points with a short italicized paragraphs prefixed with to summarize spread throughout the text. I suppose these to summarize blocks come from Comer's personal experience of which points to emphasize to students. I would find them useful if I was studying the material for a test.
I found Comer's discussion of the programs ping and traceroute informative and useful. I also liked the discussion of fragmentation and packet reassembly. But as an experienced network programmer, they were superficial (concentrating on the concept, rather than the implementation).
Comer's book is not intended for electrical engineers, but people who want to learn how networks work. In Tanenbaum, physical mediums are discussed in depth, with a good discussion of topics such as Manchester encoding, wireless communications, the telephone company and how modems work, ISDN and ATM and 10 Mbit versus 100 Mbit ethernet. One of the things Tanenbaum does extremely well is put all these things into a historical perspective, giving background into how these things evolved (in addition to the technical aspects of how they work, along with numerous references).
Tanenbaum is full of wry (and sometimes side-splitting) humor. For example, there is a saying in the book when he discuss network carrier bandwidth:
"Never underestimate the bandwidth of a station wagon full of tapes hurtling down the highway." -- page 83
Such advice is both humorous and practical.
Comer has a chapter (12 pages) on the Berkeley socket API. Tanenbaum mentions the socket API briefly (1 page). From experience, if the reader wants to write source code, a more complete description is needed with examples (these are available in Comer/David Stevens' Internetworking with TCP/IP Volume III, Prentice-Hall, 1993 or Richard Stevens' Unix Network Programming, 2nd Edition, Prentice-Hall, 1997).
Both books cover a full range of network applications (DNS, email and SMTP, SMNP, http and java). Comer also covers basic protocols like ftp. They both cover network security, but Comer deals with it in about 5 pages, while Tanenbaum gives it almost 50 pages (giving a good elementary lesson in cryptography). I'm personally weak on cryptography and network authentication protocols (I still need to read Schneier's Applied Cryptography) Comer didn't touch on anything I didn't know about cryptography, giving a cursory overview of the topic. Tanenbaum presented the information in detail, discussing attacks and solutions in an informative and entertaining way.
Comer provides a good glossary and a 9 page bibliography. Tanenbaum provides a 20 page bibliography, and a good discussion of literature available in the field. A glossary would have been useful in Tanenbaum's book, there were a few acronyms I didn't previously know which weren't in the index.
In addition, Comer provides a CD-ROM, but I wonder how useful it is. Most of the CD are the images shown in the figures of the book. In addition, there are packet traces of binary data files from the Solaris tool snoop (which appears to leave it as an exercise to the reader to write a tool to decode them). With all the space available on the CD-ROM, I'm surprised ascii files aren't distributed. In addition, I feel it would be more useful to provide tcpdump traces (which has been around for 7 years (from ftp://ftp.ee.lbl.gov, runs on a large variety of Unix systems, and was even used for examples by Richard Stevens in TCP/IP Illustrated Volume 1. With all the space available on the CD-ROM, it could have been used to distribute the entire RFC collection (which aren't mentioned in Comer's text) along with sample programs. The contents of the CD-ROM also appear to be on the web at http://www.netbook.cs.purdue.edu.
Comer is a fine book for a course, but it will not suffice as a reference book. It is focused as a textbook on a specific course. As a consumer, I thoroughly enjoyed his Prentice-Hall title The Internet Book, which is smaller, much cheaper and is not a textbook (it is intended for curious internet users). Tanenbaum's is an excellent reference book (and might be somewhat intimidating for course material, there was significant increase in size between the 2nd and 3rd edition). I wouldn't hesitate to recommend Tanenbaum for one's bookshelf or engineering course work. Comer presents a smorgasbord approach to networks, Tanenbaum is a catered, seven course meal.--Dr. Dobb's Electronic Review of Computer Books
Dr. Douglas Comer is an internationally recognized expert on TCP/IP protocols, computer networking, and the Internet. One of the researchers who contributed to the Internet as it was being formed in the late 1970s and 1980s, he was a member of the Internet Architecture Board, the group responsible for guiding the Internet's development. He was also chairman of the CSNET technical committee, a member of the CSNET executive committee, and chairman of DARPA's Distributed Systems Architecture Board.
Comer has consulted for industry on the design of computer networks. In addition to giving talks in US universities, each year Comer lectures to academics and networking professionals around the world. Comer's operating system, XINU, and implementation of TCP/IP protocols (both documented in his textbooks), have been used in commercial products.
Comer is a Distinguished Professor of Computer Science at Purdue University. He is currently on leave from Purdue, serving as VP of Research Collaboration at Cisco Systems. Recently, Comer has taught courses on networking, internetworking, computer architecture, and operating systems. He has developed innovative labs that provide students with the opportunity to gain hands-on experience with operating systems, networks, and protocols. In addition to writing a series of best-selling technical books that have been translated into 16 languages, he served as the North American editor of the journal Software — Practice and Experience for 20 years. Comer is a fellow of the ACM. For additional information, visit his web site.
Computer networks have been growing explosively. Two decades ago, few people had access to a network. Now, computer communication has become an essential part of our infrastructure. Networking is used in every aspect of business, including advertising, production, shipping, planning, billing, and accounting. Consequently, most corporations have multiple networks. Schools, at all grade levels from elementary through post-graduate, are using computer networks to provide students and teachers with instantaneous access to information in on-line libraries around the world. Federal, state, and local government offices use networks, as do military organizations. In short, computer networks are everywhere.
Continued growth of the global Internet is one of the most interesting and exciting phenomena in networking. Twenty years ago, the Internet was a research project that involved a few dozen sites. Today, the Internet has grown into a production communication system that reaches millions of people in all populated countries of the world. In the United States, the Internet connects most corporations, colleges and universities, as well as federal, state, and local government offices. It will soon reach most elementary, junior, and senior high schools. In addition, many private residences have access to the Internet through dial-up telephone connections; newer technologies are providing even higher capacity service. Evidence of the Internet's impact on society can be seen in advertisements in magazines and on television, which often contain a reference to an Internet Web site that provides additional information about the advertiser's products and services.
The growth in networking has an economic impact as well. Data networks have made telecommuting available to individuals and have changed business communication. In addition, an entire industry has emerged that develops networking technologies, products, and services. The popularity and importance of computer networking has produced a strong demand in all jobs for people with more networking expertise. Companies need workers to plan, acquire, install, operate, and manage the hardware and software systems that comprise computer networks and Internets. In addition, computer programming is no longer restricted to individual computers; programmers are expected to design and implement application software that can communicate with software on other computers.
1.2 Complexity In Network Systems
Computer networking is a complex subject. Many technologies exist, and each technology has features that distinguish it from the others. Multiple organizations have created networking standards independently, which are not all compatible. Many companies have created commercial networking products and services that use the technologies in unconventional ways. Finally, networking is complex because multiple technologies exist that can be used to interconnect two or more networks. As a result, many combinations of networks are possible.
Networking can be especially confusing to a beginner because there is no single underlying theory that explains the relationship among all parts. In fact, various organizations and research groups have attempted to define conceptual models that can be used to explain the differences and similarities among network hardware and software systems. Unfortunately, the set of technologies is diverse and changing rapidly; models are either so simplistic that they do not distinguish among details, or so complex that they do not help simplify the subject.
The lack of an underlying theory has produced another challenge for beginners: there is no simple and uniform terminology for networking concepts. Because multiple organizations define networking technologies and standards, multiple terms exist for a given concept. Professionals often use a technical term from one technology when referring to an analogous feature of another technology. In addition, technical terms are sometimes confused with the names of popular products. Consequently, in addition to a large set of terms and acronyms that contains many synonyms, networking jargon contains terms that are often abbreviated, misused, or associated with products.
1.3 Mastering The Complexity
To master the complexity, one must look beyond the details and concentrate on understanding concepts. For example, although it is not important to understand the details of wires used to connect computers to a specific network, it is important to understand the few basic categories of wiring schemes that exist and the advantages of each. Similarly, although it is not important to learn the details of how a particular communication protocol handles a congested network, it is important to know what congestion is and why it must be handled.
1.4 Concepts And Terminology
This text is written to help overcome the complexity. The text focuses on concepts and avoids unnecessary detail. It explains the purpose of each networking technology, gives the advantages and disadvantages, and describes some of the consequences of using the technology. Whenever possible, the text uses analogies and illustrations to simplify explanations.
In addition to covering concepts and technologies, the text introduces networking terminology. When a new concept is introduced, terminology for that concept is defined. The text also notes popular abbreviations and synonyms that professionals use. The terminology is summarized in a Glossary in Appendix I that serves as a quick reference for the many terms and acronyms defined throughout the text.
1.5 Organization Of The Text
Following the introductory chapters, the main part of the text is divided into four major parts. The first part describes data transmission. It explains that at the lowest level, electrical signals traveling across wires are used to carry information, and shows how data can be encoded using electrical signals. The chapters in the first part do not provide details for engineers who design networking hardware. Instead, they provide general descriptions of the principles and practical realities of data transmission and their consequences for computer networks.
The second part of the text focuses on packet transmission. It explains why computer networks use packets, and shows how data is grouped into packets for transmission. This section introduces the two basic categories of computer networks: Local Area Networks and Wide Area Networks. It explains the differences between the two categories and reviews example technologies. Finally, the section discusses the important concepts of addressing and routing. It explains how a network routes a packet to its destination.
The third part of the text covers internetworking - the important idea that allows heterogeneous network technologies to be combined into a large, seamless communication system. The text explains TCP/IP, the protocol technology used in the global Internet.
The fourth part of the text explains networking applications. It focuses on how applications use the underlying network to communicate. The part begins by explaining the client-server model of interaction. Later chapters use the model to explain how application programs provide services such as electronic mail and Web browsing....
This may be the best technical book I've ever read. I am a software developer. I needed a thorough introduction to networking to better understand and develop software architectures. This book provided that and more. <p>It didn't get bogged down in details I would never use (like the physics of twisted pair Ethernet), but presented theory followed by practical examples and common use. Topics were presented in a logical order, and built upon previous discussions. Chapters are very short, but include everything about a given topic. <p>The accompanying web site has pictures of all of the equipment discussed in the book, as well as answers to readers questions by the author. <p>I found myself unwilling to put the book down. The author makes the subject fascinating and enjoyable.
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