Milestone-Proposal:Ethernet Local Area Network (LAN), 1973-1985

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Docket #:2023-03

This Proposal has been approved, and is now a Milestone

To the proposer’s knowledge, is this achievement subject to litigation? No

Is the achievement you are proposing more than 25 years old? Yes

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy. Yes

Did the achievement provide a meaningful benefit for humanity? Yes

Was it of at least regional importance? Yes

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)? Yes

Has an IEEE Organizational Unit agreed to arrange the dedication ceremony? Yes

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated? Yes

Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes

Year or range of years in which the achievement occurred:


Title of the proposed milestone:

Ethernet Local Area Network (LAN), 1973-1985

Plaque citation summarizing the achievement and its significance:

Ethernet wired LAN was invented at Xerox Palo Alto Research Center (PARC) in 1973, inspired by the ALOHAnet packet radio network and the ARPANET. In 1980, Xerox, DEC, and Intel published a specification for 10 Mbps Ethernet over coaxial cable that became the IEEE 802.3-1985 Standard. Later augmented for higher speeds, and twisted-pair, optical, and wireless media, Ethernet became ubiquitous in home, commercial, industrial, and academic settings worldwide.

Please note that "802.3-1985 IEEE Standard" as included in the above citation is officially known as "ANSI/IEEE Std 802.3-1985."

200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.

IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.

In what IEEE section(s) does it reside?

Santa Clara Valley

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

Unit: Santa Clara Valley Section
Senior Officer Name: Liliane Peters

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: Santa Clara Valley Section
Senior Officer Name: Liliane Peters

IEEE section(s) monitoring the plaque(s):

IEEE Section: Santa Clara Valley Section
IEEE Section Chair name: Liliane Peters

Milestone proposer(s):

Proposer name: Geoffrey O. Thompson
Proposer email: Proposer's email masked to public

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):

3333 Coyote Hill Road, Palo Alto, CA 94304 Latitude: 37.4027346 Longitude: -122.1486011

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. The PARC, A Xerox Company facility is the site where Ethernet was developed and used by the Xerox PARC staff, which allowed a collection of Alto computers to communicate with each other, and with a laser printer.

Are the original buildings extant?


Details of the plaque mounting:

The plaque will be mounted in the PARC facility lobby near the Alto that is on display, and by Milestone plaques for the Alto and the Laser Printer.

How is the site protected/secured, and in what ways is it accessible to the public?

Security protected lobby, open to public daily 8am-4:30pm, 650.812.4000

Who is the present owner of the site(s)?

PARC, A Xerox Company

What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include justification here. (see section 6 of Milestone Guidelines)

Until around 1970, the mass market need for data communication was primarily long reach, i.e., not just within a building. There were several efforts to develop wide area networks (WANs) to connect large computers to each other over a distance, including the ARPANET and the UK's NPL Mark I network.

During the late 1960s and 1970s, the availability of increasingly complex and inexpensive integrated circuits led to the proliferation of affordable minicomputers and personal smaller computers intended for operation by individual users. This created a need for a Local Area Network (LAN) to enable communication between these computers in a building or site-wide campus, and at higher speeds than could be achieved with modems over voice-grade circuits.

In particular, the Xerox Palo Alto Research Center (PARC), founded in 1970, needed a high-speed interconnect for its newly-developed Alto personal computers to enable sharing of data, and access to centralized resources of laser printers, file servers, and an ARPANET gateway. By 1981, Xerox had installed 75 Ethernets at 40 sites in the USA and UK, serving over 1350 Altos, the sites interconnected via gateways and T1 and voice-grade circuits. [Ref10: Hitzik] By 1985, an estimated 500,000 Ethernet adapters had been installed worldwide, corresponding to about 100,000 Ethernets. [Ref11: Pelkey, p. 486] Within two decades, Ethernet became the dominant worldwide standard for wired local communication for computers and computing devices. [Ref9: Burg]

What obstacles (technical, political, geographic) needed to be overcome?

The Alto personal computer at Xerox PARC was a new approach to a user's workplace. Each machine had a display screen, keyboard, and mouse, and was dedicated for use by a single user. For this new workplace, PARC's employees needed a low-overhead, high-speed decentralized local communication scheme to tie together their Alto computers and the PARC laser printers, file servers, and gateway to the ARPANET.

The solution was inspired by the University of Hawaii’s ALOHA System project, and in particular its innovative design for a random-access packet broadcast channel. [Ref8: ALOHAnet, 1971 IEEE Milestone]. In 1973, Xerox PARC’s networking expert, Robert Metcalfe, who had previously worked on the ARPANET at MIT’s Project MAC, proposed a wired network to capture the ALOHAnet’s wireless “ether” into a coaxial cable with no centralized control. [Ref1: Metcalfe's 1973 Ethernet Memo] In addition, Metcalfe added a carrier sense capability, where a node would only attempt to transmit when the cable was quiescent. Metcalfe also invented a “binary exponential backoff” algorithm to improve on the ALOHAnet random retransmission algorithm in order to reduce the chance of an unstable or locked-up network under excessive loading conditions. [Ref3: US Patent No. 4,063,220], [Ref4: Comm ACM 1976] In 1973, Bob Metcalfe and Dave Boggs prototyped their Experimental Ethernet using Manchester-encoded baseband transmission at 2.94 MHz (half the Alto’s clock rate) on a shared, single-conductor, serial coaxial cable accessed via cable-puncturing taps. [Ref2: How Ethernet Was Invented], [Ref10: Hitzik]

Several obstacles to acceptance within Xerox PARC and the nascent local networking community included overcoming concerns that the network offered “only probabilistic” packet delivery, and that it exhibited indeterministic packet delivery latency under load (due to the randomized backoff retransmission algorithm). Alternative network designs based on a circulating “token" were a prominent competitive approach. In spite of the concerns and initial implementation bugs, by 1975 there were 25 nodes on PARC's Experimental Ethernet, interconnecting Altos, Data General Nova minicomputers, printers, a mainframe (MAXC), and the ARPANET, thereby demonstrating the viability of the Ethernet approach to the computing community as well as the industry. [Ref10: Hitzik], [Ref9: Burg]

Starting in 1977, Xerox began working with other companies to create an updated version of Ethernet for broad industry use. The 10 Mb/s Ethernet 1.0 "Blue Book" specification was jointly published in September 1980 by the “DIX” consortium that consisted of Digital Equipment Corporation (DEC), Intel, and Xerox. [Ref5: DIX Ethernet V1.0 1980]

The Ethernet 1.0 Blue Book specification was submitted to the newly organized IEEE 802 LAN/MAN Standards Committee as a proposal for the IEEE LAN standard. However, because there were other contenders for such a standard, the IEEE 802 Committee eventually published three standards that were incompatible for low-level LAN access: Token Bus (802.4), Token Ring (802.5), and Ethernet (802.3). The Ethernet standard, also known as CSMA/CD (“carrier-sense multiple access with collision detection”), was essentially taken from the Ethernet 1.0 Blue Book.

The 802.3 standard was approved by the IEEE on June 24, 1983, and published on December 31, 1984 as ANSI/IEEE Std 802.3-1985 IEEE Standards for Local Area Networks: Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Access Method and Physical Layer Specifications. [Ref6: IEEE 802.3-1985 Spec]

In 1990, the 802.3 IEEE standard and all of its amendments were adopted and issued by JTC1 as ISO/IEC 8802-3 1990(E). (JTC1 is a joint technical committee of the International Organization for Standardization and the International Electrotechnical Commission, and its purpose is to develop, maintain, and promote standards for information and communications technology.) Since JTC1 has adopted all amendments and all revisions to the 802.3 standard since 1990, this has led to the IEEE standard becoming ubiquitous with its worldwide adoption.

What features set this work apart from similar achievements?

Since its approval in 1983 and publication in 1985, IEEE Standard Ethernet has expanded features, media, and speeds to adapt to the broad market needs for locally-wired computer communications. Always at the forefront was both simplicity and interoperability: each step forward in the evolution of the Ethernet standard was formulated to be backward compatible with previous versions at the client interface. The use of thin coaxial media (10BASE2) lowered installation costs. Twisted-pair media (10BASE-T), in conjunction with the multi-port repeater, allowed installations to use existing surplus telephone cabling, which had often become the property of building owners after AT&T's deregulation in 1982. This reduced installation costs even more significantly, and improved both reliability and maintainability.

IEEE 802.4 never really gained volume market traction because of high cost and poor performance. IEEE 802.3's adoption of the hub and spoke architecture using IEEE 802.1 multiport switches, and the addition of automatic speed negotiation, full duplex, and higher speeds, as well as lower prices that resulted from vendor competition, let Ethernet win in the marketplace over IEEE 802.5 Token Ring. The addition of Power over Ethernet (PoE) has aided using Ethernet for connecting to IP telephones and Wi-Fi (IEEE 802.11) wireless access points. An October 2019 story for the IEEE Computer Society's COMPUTER magazine describes the history of Ethernet, and the impact of the IEEE 802.3 Standard. [Ref7: IEEE Computer 2019].

Ethernet standardizes the lower-level (data link layer) protocol. As it is agnostic with respect to higher-level packet transport-level protocols such as TCP/IP, XNS, DECNET, and the OSI protocol suites, Ethernet was unaffected by the protocol "wars" that took place in the early 1980s. The continued importance of this approach can be seen as Ethernet/IEEE 802.3 expanded into the wireless space via the Wi-Fi standard, and it is increasingly chosen as the underlying wired transport for metropolitan area networks, as well as automotive and industrial automation applications. Since the time of its initial publication in 1985, and with the JTC1's adoption of all amendments and all revisions starting in 1990, IEEE 802.3 has come to be recognized by the industry as one of the IEEE’s most successful standards.

Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.

Ref1: Metcalfe's 1973 Ethernet Memo (Xerox PARC):
Ref2: How Ethernet Was Invented, R. Metcalfe: (IEEE Annals of the History of Computing, 1994)
Ref3: US Patent No. 4,063,220:
Ref4: Ethernet: Distributed Packet Switching for Local Computer Networks, R. Metcalfe and D. Boggs (Communications of the ACM, 1976)
Ref5: DIX Ethernet V1.0 1980 (The Ethernet 1.0 "Blue Book"):
Ref6: IEEE 802.3-1985 Spec:
Ref7: Ethernet: From Office to Data Center to IoT, Geoff Thompson, (IEEE Computer, 2019)
Ref8: ALOHAnet, 1971 IEEE Milestone:,_1971
Ref9: Burg: Urs von Burg, The Triumph of Ethernet: Technological Communities and the Battle for the LAN Standard, Stanford University Press, 2002:
Ref10: Hitzik: Michael A. Hiltzik, Dealers of Lightning: Xerox PARC and the Dawn of the Computer Age, HarperCollins, 2000:
Ref11: Pelkey: James L. Pelkey & Andrew L. Russell, Circuits, Packets, and Protocols: Entrepreneurs and Computer Communications, 1968–1988, ACM Books, 2022:
IEEE History Center Oral History of Robert Metcalfe, conducted by Robert Colburn on 19 Feb. 2004:
Computer History Museum Oral History of Robert Metcalfe, conducted by Len Shustek on 29 Nov. 2006 and 31 Jan. 2007: (Video, pt. 1), (Video, pt. 2), (Full Transcript)
Ethernet Timeline: 1973-2013, created for 2013 Ethernet Technology Summit, Santa Clara, CA USA:

Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to Please see the Milestone Program Guidelines for more information.

Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s).

Please recommend reviewers by emailing their names and email addresses to Please include the docket number and brief title of your proposal in the subject line of all emails.