Designing and Managing Local Area Networks
`
`The Definitive Guide
`
`O'REILLY®
`
`Charles E. Spurgeon
`
`Designing and Managing Local Area Networks
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`
`
`
`
`
`O’REILLY”
`
`
`
`The Definitive Guide
`
`Charles E, Spurgeon
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`Ethernet: The Definitive Guide
`by Charles E. Spurgeon
`
`Copyright © 2000 O'Reilly & Associates, Inc. All rights reserved.
`Printed in the United States of America.
`
`Published by O'Reilly & Associates, Inc., 101 Morris Street, Sebastopol, CA 95472.
`
`Editors: Mark Stone and Chuck Toporek
`
`Production Editor: David Futato
`
`Cover Designer: Hanna Dyer
`
`Printing History:
`
`February 2000:
`
`First Edition.
`
`Nutshell Handbook, the Nutshell Handbook logo, and the O'Reilly logo are registered
`trademarks of O'Reilly & Associates, Inc. Many of the designations used by manufacturers and
`sellers to distinguish their products are claimed as trademarks. Where those designations
`appear in this book, and O'Reilly & Associates, Inc. was aware of a trademark claim, the
`designations have been printed in caps or initial caps. The association between the image of
`an octopus and the topic of Ethernet is a trademark of O'Reilly & Associates, Inc. SC connector
`is a trademark of NTT Advanced Technology Corporation. ST connector is a trademark of
`American Telegraph & Telephone.
`
`Some portions of this book have been previously published and are reprinted here with
`permission of the author. Portions of the information contained herein are reprinted with
`permission from IEEE Std 802.3, Copyright© 1995, 1996, 1999, by IEEE. The IEEE disclaims
`any responsibility or liability resulting from the placement and use in the described manner.
`
`While every precaution has been taken in the preparation of this book, the publisher assumes
`no responsibility for errors or omissions, or for damages resulting from the use 9f the
`information contained herein.
`
`Library of Congress Cataloging-in-Publication Data
`Spurgeon, Charles (Charles E.)
`Ethernet: the definitive guide I Charles E. Spurgeon
`p. cm.
`ISBN 1-56592-660-9 (alk. paper)
`1. Ethernet (Local area network system) I. Title.
`
`TK5105.8.E83 S67 2000
`004.6'8--dc21
`
`[Ml
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`99-086932
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`Table of Contents
`
`Preface ..................................................................................................................... xi
`
`1 Introduction to Ethernet ................................................................ J
`
`1. The Evolution of Ethernet ...................................................................... 3
`History of Ethernet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
`The Latest Ethernet Standard ........................................................................... 8
`Organization of IEEE Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 O
`Levels of Compliance ............................................. '. ....................................... 13
`IEEE Identifiers ............................................................................................... 15
`Reinventing Ethernet ...................................................................................... 19
`Multi-Gigabit Ethernet .................................................................................... 22
`
`2. The Ethernet System ......................................... : .................................... 23
`Four Basic Elements of Ethernet ................................................................... 24
`Ethernet Hardware ......................................................................................... 29
`Network Protocols and Ethernet .................................................... · .......... : .... 34
`
`3. The Media Access Control Protocol .................................................. 39
`The Ethernet Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
`Media Access Control Rules .................. : ....................................................... 47
`·Essential Media System Timing ..................................................................... 50
`Collision Detection and Backoff ................................................................... 53
`Gigabit Ethernet Half-Duplex Operation ...................................................... 60
`Collision Domain ........................................................................................... 65
`Ethernet Channel Capture ............................................................................. 67
`High-level Protocols and the Ethernet Frame .............................................. 70
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`vi
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`Table of Contents
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`4. Full-Duplex Ethernet . .. . .. .. . . . . . .. . . . . .. . . . . . . .. . .. . ... . . . . . . . .. . . .. ... . . . ... . . . .. . . . . . . . . . ... ... 7 6
`Operation of Full-Duplex .............................................................................. 77
`Ethernet Flow Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
`
`5. Auto-Negotiation .... : ................................................................................ 85
`Development of Auto-Negotiation ................................................................ 85
`Basic Concepts of Auto-Negotiation .. .. .. .. ... .. . .... .. . .. . .. .......... ... .. . .. .... .. . ...... .... 86
`Auto-Negotiation Signaling ............................................................................ 87
`Auto-Negotiation Operation .......................................................................... 90
`Parallel Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
`Management Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
`lOOOBASE-X Auto-Negotiation ...................................................................... _96
`
`IL Ethernet Media Systems ............................................................... 99
`
`6. Ethernet Media Fundamentals ....................................................... 101
`Attachment Unit Interface . . . . . . . . . . . .. . .. . . . . . . . . . .. .. . .. .. . . . . .. . . . . .. . .. . . . . . . . . . .. ... . . . . . .. .. . . . .. 102
`Medium-Independent Interface ....................... : ........................................... 108
`Gigabit Medium-Independent Interface ...................................................... 114
`Ethernet Signal Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
`Ethernet Network Interface Card ................................................................ 122
`
`7. Twisted-Pair Media System (JOBASE-1) ....................................... 125
`lOBASE-T Signaling Components ................................................................ 125
`lOBASE-T Media Component~ ..................................................................... 128
`lOBASE-T Configuration Guidelines .............................................. _ ............. 132
`
`8. Fiber Optic Media System (JOBASE-F) .......................................... 134
`Old and New Fiber Link Segments ............................................................. 134
`lOBASE-FL Signaling Components .............................................................. 136
`lOBASE-FL Media Components ................................................................... 137
`Connecting a Station to lOBASE-FL Ethernet ............................................. 139
`lOBASE-FL Configuration Guidelines .. .. .. .. .. .. .... .. .. .. .. .. .. .. .. ... ...... .. .. .. .. .. ..... .. 140
`
`9. Fast Ethernet Twisted-Pair Media System (1 OOBASE-TX) ...... 142
`lOOBASE-TX Signaling Components ........................................................... 142
`lOOBASE-TX Media Components ................................................................ 145
`Connecting a Station to lOOBASE-TX Ethernet ........................................... 146
`lOOBASE-TX Configuration Guidelines ....................................................... 147
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`10. Fast Ethernet Fiber Optic Media System (1 OOBASE-FX) ........ 149
`lOOBASE-FX Signaling Components ........................................................... 149
`lOOBASE-FX Media Components ......... : ...................................................... 152
`Connecting a Station to lOOBASE-FX Ethernet ........................................... 153
`lOOBASE-FX Configuration Guidelines ....................................................... 154
`
`11. Gigabit Ethernet Twisted-Pair
`Media System (JOOOBASE-1) ....................... ; .................................... 156
`lOOOBASE-T Signaling Components ............................................................ 157
`lOOOBASE-T Signal Encoding ...................................................................... 158
`lOOOBASE-T Media Components ................................................................. 160
`Connecting a Station to lOOOBASE-T Ethernet ........................................... 162
`lOOOBASE-T Configuration Guidelines . .. . .. .. .. .. .. .. . .. .. . .. .. .. .. .. .. .. .. .. . .. . .. . .. .. . .. . 163
`
`12. Gigabit Ethernet Fiber Optic Media System (1 OOOBASE-X) . 164
`lOOOBASE-X Signaling Components ........................................................... 165
`lOOOBASE-X Signal Encoding ...................................................................... 166
`lOOOBASE-X Media Components ................................................................ 167
`lOOOBASE-SX and lOOOBASE-LX Media Components .. .. .. . .... .... .... .. .... .. ... .. 168
`lOOOBASE-CX Media Components .. . . .. . .. .... . . .. . .. . . . ... . . .. . . . . . . .. . .. . . . . .. . ... .. . .. . . . ... 169
`lOOOBASE-SX and lOOOBASE-LX Configuration Guidelines ....................... 171
`
`13. Multi-Segment Con.figuration Guidelines .................................... 173
`Scope of the Configuration Guidelines ....................................................... 174
`Network Documentation ............................................................................. i74
`Collision Domain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4
`Model 1 Configuration Guidelines for 10 Mbps .. .. .. . .. . .. .. .. .. .. .. .. .. . .. . .. .. .. . .. .. 17 6
`Model 2 Configuration Guidelines for 10 Mbps .. .. . .. .. .. .. . .. .. .. .. .. .. .. .. .. .. . .. .. .. 177
`Model 1 Configuration Guidelines for Fast Ethernet .. . .. .. .. .. . .. .. .. . .. .. .. .. . .. .. . 184
`Model 2 Configuration Guidelines for Fast Ethernet .. .. .. . .. .. .. . .. . .. . .. . .. .. .. .. .. 186
`Model 1 Configuration Guidelines for Gigabit Ethernet .. .. .. .. .. . .. .. .. .. .. . .. .. .. 190
`Model 2 Configuration Guidelines for Gigabit Ethernet . .. .. . .. .. . .. .. .. .. .. .. .. . .. 191
`Sample Network Configurations ..................... : ........................................... 193
`
`III Building Your Ethernet System ............................................. 203
`
`14. Structured Cabling ............................................................................... 205
`Structured Cabling Systems ..................... :. .. . .. . . .. . . .. .. .. . . . . . . . .. . .. . . . .. . .. .. . .. . . . .. . . . 206
`TIA/EIA Cabling Standards .......................................................................... 207
`Twisted-Pair Categories ............................................................................... 211
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`viii
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`Table of Contents
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`Ethernet and the Category System . .. . .. .. .. .. .. .. . .. . .. .. . . . .. . .. .. .. .. .. .. .. .. . .. . .. . .. .. .. . .. 213
`Horizontal Cabling .. .. . .. . .. .. . . . . . . . . . .. . . . . . . .. . .. .. . . . .. . . . .. . .. . . . . . . . .. . . . .. . .. . .. . .. . .. . .. . .. . . . . .. 214
`New Twisted-Pair Standards ........................................................................ 217
`Identifying the Cables .................................................................................. 219
`Documenting the Cable System .................................................................. 221
`Building the Cabling System .. .. . .. .. .. .. .. .. .. . .. .. .. . .. .. .. .. .. .. . .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. . 222
`
`15. Twisted-Pair Cables and Connectors ............................................. 224
`Category 5 Horizontal Cable Segment .. .. .. . .. .. .. .. .. .. .. .. .. .. .. . .. .. .. .. .. . .. .. .. .. .. .. .. . 224
`Eight-Position (RJ-45-Style) Jack ................................................................. 230
`Four-Pair Wiring Schemes ........................................................................... 230
`Modular Patch Panel .. .. . . . . . .. .. . . . .. . .. . .. . . .. . . . .. . . . . . .. . .. . .. . . . . . . .. . . . . . .. . . . . .. .. . .. . .. . . . . . . . . . 234
`Work Area Outlet .......................................................................................... 235
`Twisted-Pair Patch Cables ........................................................................... 236
`Building a Twisted-Pair Patch Cable ........................................................... 239
`Ethernet Signal Crossover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
`Twisted-Pair Ethernet and Telephone Signals ............................................ 248
`
`16. Fiber Optic Cables and Connectors ............................................... 249
`Fiber Optic Cable . . . .. . . . . . . . . .. . . . .. . . . .. . . . . . . .. . . . . . . . . . . . . .. . .. . .. . . .. . . . .. . . . . . . . . . . .. . . .. . .. . . . . .. . . 249
`lOBASE-FL Fiber Optic Characteristics ........................................................ 256
`lOOBASE-FX Fiber Optic Characteristics ..................................................... 257
`lOOOBASE-X Fiber Optic Characteristics ..................................................... 258
`
`17. Ethernet Repeater Hubs ..................................................................... 264
`Collision Domain ......................................................................................... 265
`Basic Repeater Operation ............................................................................ 266
`Repeater Buying Guide ... ~·.......................................................................... 269
`10 Mbps Repeaters ....................................................................................... 276
`100 Mbps Repeaters ..................................................................................... 281
`1000 Mbps Gigabit Ethernet Repeater ........................................................ 285
`Repeater Management ................................................................................. 286
`Repeater Port Statistics ................................................................................. 289
`
`18. Ethernet Switching Hubs ................................................................... 298
`Brief Tutorial on Ethernet Bridging ............................................................ 299
`Advantages of Switching Hubs .................................................................... 306
`Switching Hub Performance Issues ............................................................. 311
`Advanced Features of Switching Hubs ....................................................... 314
`Network Desisn Issues with Switches ........................................................ 320
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`ix
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`W. Performance and Troubleshooting .................................. :. 325
`
`19. Ethernet Performance ......................................................................... 327
`Performance of an Ethernet Channel .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. 328
`Measuring Ethernet Performance ......................................... ~ ...................... 334
`Network Performance and the User ........................................................... 338
`Network Design for Best Performance ....................................................... 342
`
`20. Troubleshooting .................................................................................... 346
`Reliable Network Design ............................................................................. 347
`Network Documentation ....................................... : ..................................... 348
`The Troubleshooting Model ........................................................................ 350
`'
`Fault Detection . . .. . . . .. . . . .. . . . . . . . . . . . .. . . . . . . . .. . . .. .. . . . . .. . . . . . . . . . . .. . . .. . . . . . . . . . . . . . . . .. .. . . .. . . .. .. 352
`Fault Isolation ............................................................................................... 354
`Troubleshooting Twisted-Pair Systems ....................................................... 357
`Troubleshooting Fiber Optic Systems ......................................................... 361
`Data Link Troubleshooting .......................................................................... 364
`Network Layer Troubleshooting ................................................................ ., 368
`
`V. Appendixes .......................................................................................... 3 71
`
`A. Resources ................................................................................................. 373
`
`B. Thick and Thin Coaxial Media Systems ...................................... 383
`
`C. AU! Equipment: Installation and Configuration ..................... 430
`
`Glossary ............................................................................................. : ................ 441
`
`Index ..................................................................................................................... 459
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`I
`
`Introduction to Ethernet
`
`The first part of this book provides a tour of basic Ethernet theory and operation.
`These chapters cover those portions of Ethernet operation that are common to
`all Ethernet media systems. Common portions include the Ethernet frame, the
`operation of the media access control system, full-duplex mode, and the Auto(cid:173)
`Negotiation protocol.
`
`Part I contains these chapters:
`
`• Chapter 1, The Evolution of Ethernet
`• Chapter 2, The Ethernet System
`• Chapter 3, The Media Access Control Protocol
`• Chapter 4, Full-Duplex Ethernet
`• Chapter 5, Auto-Negotiation
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`In this chapter:
`• History of Ethernet ·
`• The Latest Ethernet
`Standard
`• Organization of IEEE
`Standards
`• Levels of Compliance
`• IEEE Identifiers
`• Reinventing Ethernet
`• Multi-Gigabit
`Ethernet
`
`The Evolution of
`Ethernet
`
`Ethernet is by far the most widely used local area networking (LAN) technology in
`the world today. Market surveys indicate that hundreds of millions of Ethernet net(cid:173)
`work interface cards (NICs), repeater ports, and switching hub ports have been
`sold to date, and the market continues to grow. In total, Ethernet outsells all other
`LAN technologies by a very large margin.
`
`Ethernet reached its 25th birthday in 1998, and has seen many changes as com(cid:173)
`puter technology evolved over the years. Ethernet has been constantly reinvented,
`evolving new capabilities and in the process growing to become the most popular
`network technology in the world.
`
`This chapter describes the invention of Ethernet, and the development and organi(cid:173)
`zation of the Ethernet standard. Along the way we provide a brief tour of the
`entire set of Ethernet media systems.
`
`History of.Ethernet
`On May 22, 1973, Bob Metcalfe (then at the Xerox Palo Alto Research Center,
`PARC, in California) wrote a memo describing the Ethernet network system he had
`invented for interconnecting advanced computer workstations, making it possible
`to send data to one another and to high-speed laser printers. Probably the best(cid:173)
`known invention at Xerox PARC was the first personal computer workstation with
`graphical user interfaces and mouse pointing device, called the Xerox Alto. The
`PARC inventions also included the first laser printers for personal computers, and,
`with the creation of Ethernet, the first high-speed LAN technology to link every(cid:173)
`thing together.
`
`This was a remarkable computing environment for the time, since the early 1970s
`were an era in which computing was dominated by large and very expensive
`
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`4
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`Chapter 1: The Evolution of Ethernet
`
`mainframe computers. Few places could afford to buy and support mainframes,
`and few people kne~ how to use them. The inventions at Xerox PARC helped
`bring about a revolutionary change in the world of computing.
`
`A major part of this revolutionary change in the use of computers has been the
`use of Ethernet LANs to enable communication among computers. Combined with
`an explosive increase in the use of information sharing applications . such as the
`World Wide Web, this new model of computing has brought an entire new world
`of communications technology into existence. These days, sharing information is
`most often done over an Ethernet; from the smallest office to the largest corpora(cid:173)
`tion, from the single schoolroom to the largest university campus, Ethernet is
`clearly the networking technology of choice.
`
`The Aloha Network
`Bob Metcalfe's 1973 Ethernet memo describes a networking system based on an
`earlier experiment in networking called the Aloha network. The Aloha network
`began at the University of Hawaii in the late 1960s when Norman Abramson and
`his colleagues developed a radio network for communication among the Hawai(cid:173)
`ian Islands. This system was an early experiment in the development of mecha(cid:173)
`nisms for sharing a common communications channel-in this case, a common
`radio channel.
`
`The Aloha protocol was very simple: an Aloha station could send whenever it
`liked, and then waited for an acknowledgment. If an acknowledgment wasn't
`received within a short amount of time, the station assumed that another station
`had also transmitted simultaneously, causing a collision in which the combined
`transmissions were garbled so that the receiving station did not hear them and did
`not return an acknowledgment. Upon detecting a collision, both transmitting sta(cid:173)
`tions would choose a random backoff time and then retransmit their packets with
`a good probability of success. However, as traffic increased on the Aloha channel,
`the collision rate would rapidly increase as well.
`
`Abramson calculated that this system, known as pure Aloha, could achieve a maxi(cid:173)
`mum channel utilization of about 18 percent due to the rapidly increasing rate of
`collisions under increasing load. Another system, called slotted Aloha, was devel(cid:173)
`oped that assigned transmission slots and used a master clock to synchronize
`transmissions, which increased the maximum utilization of the channel to about 37
`percent. In 1995, Abramson received the IEEE's Koji Kobayashi Computers and
`Communications Award "for development of the concept of the Aloha System,
`which led to modern local area networks."
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`History of Ethernet
`
`5
`
`Invention of Ethernet
`Metcalfe realized that he could improve on the Aloha system of arbitrating access
`to a shared communications channel. He developed a new system that included a
`mechanism that detected when a collision occurred (collision detect). The system
`also included "listen before talk," in which stations listened for activity (carrier
`sense) before transmitting, and supported· access to a shared channel by multiple
`stations (multiple access). Put all these components together, and you can see why
`the Ethernet channel access protocol is called Carrier Sense Multiple Access with
`Collision Detect (CSMA/CD). Metcalfe~ also developed a more sophisticated back(cid:173)
`off algorithm, which, in combination with the CSMA/CD protocol, allowed the
`Ethernet system to function at up to 100 percent load.
`
`In late 1972, Metcalfe and his Xerox PARC colleagues developed the first experi(cid:173)
`mental Ethernet system to interconnect the Xerox Alto. The experimental Ethernet
`was used to link Altos to one another, and to servers and laser printers. The sig(cid:173)
`nal clock_ for the experimental Ethernet interface was derived from the Alto's sys(cid:173)
`tem clock, which resulted in a data transmission rate on the experimental Ethernet
`of 2.94 Mbps.
`
`Metcalfe's first experimental network was called the Alto Aloha Network. In 1973,
`Metcalfe changed the name to "Ethernet," to make it clear that the system could
`support any computer-not just Altos-and to point out that his new network
`mechanisms had evolved well beyond the Aloha system. He chose to base the
`name on the word "ether" as a way of describing an essential feature of the sys(cid:173)
`tem: the physical medium (i.e., a cable) carries bits to all stations, much the same
`way that the old "luminiferous ether" was once thought to propagate electromag(cid:173)
`netic waves through space.* Thus, Ethernet was born.
`
`In 1976, Metcalfe drew the following diagram (Figure 1-1) " ... to present Ethernet
`for the first time. It was used in his presentation to the National Computer Confer(cid:173)
`ence in June of that year. On the drawing are the original terms for describing
`Ethernet. Since then, other terms have come into usage among Ethernet enthusi(cid:173)
`asts. "t
`
`In July 1976, Bob Metcalfe and David Boggs published their landmark paper
`"Ethernet: Distributed Packet Switching for Local Computer Networks," in the
`Communications of the Association for Computing Machinery (CACM). In late
`1977, Robert M. Metcalfe, David R. Boggs, Charles P. Thacker, and Butler W.
`
`• Physicists Michelson and Morley disproved the existence of the ether in 1887, but Metcalfe decided that
`it was a good name for his new network system that carried signals to all computers.
`t From The Ethernet Sourcebook, ed. Robyn E. Shotwell (New York: North-Holland, 1985), title page. Dia(cid:173)
`gram reproduced with permission.
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`6
`
`Chapter 1: The Evolution of Ethernet
`
`IM\.IOC€\~~~·
`~ .
`x ;IK'fE'2fACE. q..ao;t.
`
`.
`
`Figure 1-1. Drawing of the original Ethernet system
`
`Lampson received U.S. patent number 4,063,220 on Ethernet for a "Multipoint Data
`Communication System With Collision Detection." A patent for the Ethernet
`repeater was issued in mid-1978. At this point, Xerox wholly owned the Ethernet
`system. The next stage in the evolutfon of the world's most popular computer net(cid:173)
`work was to liberate Ethernet from the confines of a single corporation and make
`it a worldwide standard.
`
`Evolution of the Ethernet Standard
`The original 10 Mbps Ethernet standard was first published in 1980 by the DEC(cid:173)
`Intel-Xerox vendor consortium. Using the first initial of each company, this
`became known as the DIX Ethernet standard. This standard, entitled Tbe Ethernet,
`A Local Area Network: Data Link Layer and Physical Layer Specifications, con(cid:173)
`tained the specifications for the operation of Ethernet as well as the specs for a
`single media system based on thick coaxial cable. As is true for most standards,
`the DIX standard was revised to add some technical changes, corrections, and
`minor improvements. The last revision of this standard was DIX V2.0.
`
`When the DIX standard was published, a new effort led by the Institute of Electri(cid:173)
`cal and Electronics Engineers (IEEE) to develop open network standards was also
`getting underway.* Consequently, the thick coaxial variety of Ethernet ended up
`being standardized twice-first by the f)IX consortium and a second time by the
`IEEE. The IEEE standard was created under the direction of the IEEE Local and
`Metropolitan Networks (LAN/MAN) Standards Committee, which identifies all the
`standards it develops with the number 802. There have been a number of net-
`
`• The IEEE is the world's largest technical professional society, with members in 150 countries. The IEEE
`provides technical publishing, holds conferences, and develops a range of technical standards, includ(cid:173)
`ing computer and communications standards. The standards developed by the IEEE may also become
`national and international standards.
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`History of Ethernet
`
`7
`
`working standards published in the 802 branch of the IEEE, including the 802.3*
`Ethernet and 802.5 Token Ring standards.
`
`The IEEE 802.3 committee took up the network system described in the original
`DIX standard and used it as the basis for an IEEE standard. The IEEE standard was
`first published in 1985 with the title IEEE 802.3 Carrier Sense Multiple Access with
`Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications.
`The IEEE standard does not use "Ethernet" in the title, even though Xerox relin(cid:173)
`quished their trademark on the Ethernet name. That's because open standards
`committees are quite sensitive about using commercial names that might imply
`endorsement of a particular company. As a result, the IEEE calls this technology
`802.3 CSMA!CD or just 802.3 However, most people still use the Ethernet name
`when referring to the network system described in the 802.3 standard.
`
`The IEEE 802.3 standard is the official Ethernet standard. From time to time you
`may hear of other Ethernet technology "standards" developed by various groups or
`vendor consortiums. However, if the technology isn't specified within the IEEE
`802.3 standard, it isn't an official Ethernet technology. Periodically, the latest IEEE
`802.3 standards are presented to the American National Standards Institute (ANSI),
`which forwards them on, where they are adopted by the International Organiza(cid:173)
`tion for Standardization (ISO). This organization is described in more detail later in
`this chapter. Adoption by the ISO means that the IEEE 802.3 Ethernet standard is
`also a worldwide standard, and that vendors from around the globe can build
`equipment that will work together on Ethernet systems.
`
`Ethernet Family Tree
`The title of the latest version of the IEEE standard as of this writing is 802.3,
`1998 Edition Information Technology-Telecommunications and information
`exchange between systems-Local and metropolitan area networks-Specific
`requirements-Part 3: Carrier sense multiple access with collision detection
`(CSMA/CD) access method and physical layer specifications.
`
`This edition contains 1,268 pages and "includes all contents of the 8802-3:1996
`Edition, plus IEEE Std 802.3aa-1998, IEEE Std 802.3r-1996, IEEE Std 802.3u-
`1995, IEEE Std 802.3x&y-1997, and IEEE802.3z-1998." These latter documents
`were developed as supplements to the standard. This edition of the standard
`can be purchased from the IEEE through their web site at: http://standards. ieee.
`org/catalog/IEEE802.3.html.
`
`* Pronounced "eight oh two dot three."
`
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`8
`
`Chapter 1: The Evolution of Ethernet
`
`The Latest Ethernet Standard
`After the publication of the original IEEE 802.3 standard for thick Ethernet, the
`next development in Ethernet media was the thin coaxial Ethernet variety, inspired
`by technology first marketed by the 3Com Corporation. When the IEEE 802.3 com-
`. m