Gigabit Ethernet promises to be the solution of choice for ultra-high-speed connections in many of today's LANs. A logical extension of the well-known Ethernet technology, it offers blazing speed capability with minimal disruption to existing network configurations and operations.
Gigabit Ethernet provides the capacity required for bandwidth-hungry servers, campus backbone networks, and next-generation workstations. Furthermore, it provides a seamless upgrade path from existing 10 Mb/s and 100 Mb/s Ethernet networks. All of the skills, tools, training, and experience gained from using lower-speed Ethernet LANs can be applied to the new technology, easing the pain of migration.
Appropriate for anyone involved with LAN technologiesaenetwork planners, designers and administrators, equipment and applications developers, technical salespeople, studentsaethis book provides a thorough explanation of Gigabit Ethernet and the principles on which it was built.
Gigabit Ethernet explains the technology in clear terms, exploring the implications for its application and operation in real-world LANs. You will learn how to identify appropriate application environments for Gigabit Ethernet, as well as how to integrate it with other technologies, make intelligent choices about products and features, and set realistic expectations about performance.
In this comprehensive book, you will find essential information on:
This book contains a convenient summary of the IEEE 802.3z Gigabit Ethernet standard. Also, to provide a perspective on Gigabit Ethernet's role relative to other high-performance LANs, Mr. Seifert compares Gigabit Ethernet to such alternative technologies as Fibre Channel, FDDI, HIPPI, and ATM.
I. FOUNDATIONS OF GIGABIT ETHERNET.1. Ethernet before Gigabit.
A Brief History of Ethernet.
Why Is Ethernet so Popular?
Ethernet Swings Like a Pendulum Do.
A Word on Nomenclature.
Getting to Gigabit.2. From Shared to Dedicated Media.
Why Coaxial Cable in the First Place?
The Transition to Structured Wiring.
Advantages of Structured Wiring.
The 10BASE-T/100BASE-T Revolution.
Dedicated Media and Gigabit Ethernet.3. From Shared to Dedicated LANs.
Shared-Bandwidth LAN Concepts.
A Switch Is a Bridge.
Switched LAN Concepts.
Cost versus Performance.
Implications of Switches for Gigabit Ethernet.4. Full-Duplex Ethernet.
“Ethernet Is CSMA/CD.”
Why a MAC?
Implications of Full-Duplex Operation.
Full-Duplex Application Environments.
Application of Full-Duplex Mode to Gigabit Ethernet.5. Frame Formats.
But First, a Word on Notation and Bit/Byte Ordering.
The DIX Ethernet Frame.
The IEEE 802.3 Frame Format (1985-1996).
The IEEE 802.3 Frame Format (1997).6. Ethernet Flow Control.
The Need for Flow Control in Ethernet.
Flow Control Implementation Issues.
Flow Control Symmetry.7. Ethernet Medium Independence.
Ethernet Is Multimedia!
10 Mb/s Attachment Unit Interface.
100 Mb/s Medium-Independent Interface.
Medium Independence and Gigabit Ethernet.
Summary of Medium-Independent Interfaces.8. Automatic Configuration.
The Driving Forces behind Automatic Configuration.
Auto-Negotiation on UTP Systems.
Auto-Negotiation on Optical Fiber.
Automatic Configuration for Gigabit Ethernet.
II. GIGABIT ETHERNET TECHNOLOGY.9. Architecture and Overview of Gigabit Ethernet.
Gigabit Ethernet Architecture.
Overview of Gigabit Ethernet Technology.10. Gigabit Ethernet Media Access Control.
Rationale and Target Applications for Half- versus Full-Duplex Gigabit Ethernet.11. Gigabit Ethernet Hubs.
Routing Hubs.12. Gigabit Ethernet Physical Layer.
Physical Layer Architecture.
Physical Layer Design Guidelines.13. The Hitchhiker’s Guide to the Gigabit Ethernet Standard.
What Is IEEE 802.3?
What Is IEEE 802.3z?
Target Audience and Reader Assumptions.
The IEEE 802.3z Standard.
III. APPLYING GIGABIT ETHERNET.14. Application Environments.
LAN Interconnection.15. Performance Considerations.
End-to-End Communications Paths.
Measuring and Improving Performance.16. Technology Alternatives.
Fiber Distributed Data Interface.
High-Performance Parallel Interface.
Asynchronous Transfer Mode.
Appendix A: 8B/10B Code Tables.
During the 1980s and 1990s, the growth in the use of computer networks has been nothing short of phenomenal. No longer do organizations consider whether they need a network, but only what type of network should be employed. The parallel growth in the capabilities of the devices connecting to the networks (personal computers, workstations, servers, and so on) and the applications using those networks have combined to transform yesterday's network technologies into a performance roadblock. Like our freeways, we constantly add lanes only to find that the traffic demand simply increases to keep the road as congested as always.
Gigabit Ethernet, conceived in 1995, is the most recent addition to the world's most popular family of local area network (LAN) technologies. The lure of riding yet another wave of successful Ethernet systems has attracted enormous interest from vendors eager to provide new products to feed bandwidth-hungry network applications. In that year, the Institute for Electronics and Electrical Engineers (IEEE) LAN/MAN Standards Committee began the process of developing an industry standard for Gigabit Ethernet. While the gestation period of an IEEE standard may exceed even that of an elephant, the IEEE 802.3z Gigabit Ethernet standard is expected to be formally approved by IEEE in mid-1998 and is already endorsed by dozens of equipment manufacturers. Even more important, products are becoming available for users to deploy in their networks.
This book guides both users and developers through the complex issues involved in designing and deploying high-speed networks.
This book is aimed at the needs of both:
The reader is assumed to be at least casually familiar with LANs and Ethernet in particular. No attempt is made to provide a complete, from-the-ground-up tutorial suitable for novices. Indeed, such a work would require an encyclopedia and make it impossible to focus on Gigabit Ethernet and the related technologies on which it builds and relies. Network technologists and users grounded in the fundamentals of Ethernet will find everything they need to understand completely the workings of the new Gigabit Ethernet system. In the process, they will gain enormous insight into why things are done the way they are at 10, 100, and 1000 Mb/s, and not just the cold facts.
This book is not intended as a "standards companion." While a summary of the standard itself is provided (Chapter 13), the bulk of the book is concerned with helping the reader to understand Gigabit Ethernet technology and the ways in which it may best serve the needs of real applications. A conscious effort has been made to use practical, everyday terminology, rather than the Arcane Architectural Abstractions and Acronyms (AAAAAs) typical of standards documents.
The book is organized into three main sections:
It's a daunting task to write a book of this depth and magnitude. Fortunately, I had the help of numerous experts who reviewed material, corrected my errors, and gave excellent advice on the content and organization of this work. Thanks to: Carsten Bormann, Bob Fink, Howard Frazier, Andy Hacker, Frank Kastenholz, Dennis Miller, Rex Naden, Thomas Skibo, Joel Snyder, Rich Taborek, and Geoff Thompson, and especially to Greg Hersh, Bert Manfredi, and Mart Molle for their time and advice. Thanks also to Mary Harrington and Genevieve Rajewski for all of their help with the nuts and bolts of publishing and to Carol Long for navigating the winding roads of the Santa Cruz Mountains and getting me started on this project in the first place.
I also would like to thank all of my consulting clients, whose interesting projects continually force me to stay on top of current technologies, and my students at the University of California at Berkeley, who (unbeknownst to them) provided a testing ground for most of the figures, tables, and material in the book. Thanks also to my colleagues in the IEEE 802.3 Working Group and IEEE 802.3z Gigabit Ethernet Task Force, who consistently develop the highest-quality and most widely adopted standards in the LAN industry.
Of course, any errors contained in this work are my responsibility alone.
Network technology changes quickly, especially in relation to the time required to write and publish a book such as this one. This book was written contemporaneously with the development of the Gigabit Ethernet standard; at the time of publication, the standard had not yet been formally approved. As a result, there may be minor differences between some operational parameters presented here and those of the final approved standard. Also, work on Gigabit Ethernet will not come to a halt when the first revision of the standard is approved. There are ongoing projects both to expand the usefulness of the technology, and to correct and maintain the standard.
To keep you informed with the most up-to-date information, including any corrections to this book, I will be maintaining a World Wide Web site for this purpose, at:
I welcome your feedback, both on the usefulness (or not) of this book, as well as any additions or corrections that should be made in future editions. While I can't guarantee a personal response to everyone, please feel free to contact me:
Networks & Communications Consulting
21885 Bear Creek Way
Los Gatos, CA 95033
(408) 395-1966 (fax)