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Metcalfe's Ethernet Memo

Metcalfe's Ethernet Memo

Image creditRobert Metcalfe, sketches from the May 22, 1973 Xerox memo (image via IEEE ETHW)
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Metcalfe's Ethernet Memo

Year
1973
Creator
Robert Metcalfe, David Boggs
Company
Xerox Palo Alto Research Center (PARC)
Location
Palo Alto, California

Description

In a Xerox memo of May 22, 1973, Bob Metcalfe proposed a network that would connect the Altos at PARC with a shared coaxial cable. The image shows the original sketch of the idea by Metcalfe, with a cable tree that he called an ether.

Importance

Metcalfe took the random-access method of the ALOHAnet radio network in Hawaii and added carrier sense and a backoff rule. With these changes, many Altos could share one cable without a central controller. Xerox, DEC, and Intel published a 10 Mbps specification in 1980, which became the IEEE 802.3 standard.

Interesting fact

By 1975, the experimental Ethernet at PARC connected 25 nodes, which included Altos, printers, a mainframe, and a gateway to the ARPANET.

Sources

  1. Milestones: Ethernet Local Area Network (LAN), 1973-1985 ↗IEEE, Engineering and Technology History Wiki · 2024-05-17
  2. Timeline of Computer History: 1973 ↗Computer History Museum
  3. Xerox Alto Source Code (Paul McJones) ↗Computer History Museum · 2014-10-21
  4. File:Ethernet-sketch.jpg ↗IEEE, Engineering and Technology History Wiki · 2024-06-10
  5. Ethernet ↗Wikipedia
  6. Living legends: Ethernet inventor Bob Metcalfe ↗Network World, via Internet Archive · 2011-05-09