An 8P8C modular connector (often called RJ45) commonly used on cat 5 cables in Ethernet networks

Ethernet  /ˈiːθərnɛt/ is a family of computer networking technologies for local area networks (LANs). Ethernet was commercially introduced in 1980 and standardized in 1985 as IEEE 802.3. Ethernet has largely replaced competing wired LAN technologies.

The Ethernet standards comprise several wiring and signaling variants of the OSI physical layer in use with Ethernet. The original 10BASE5 Ethernet used coaxial cable as a shared medium. Later the coaxial cables were replaced by twisted pair and fiber optic links in conjunction with hubs or switches. Data rates were periodically increased from the original 10 megabits per second, to 100 gigabits per second.

Systems communicating over Ethernet divide a stream of data into shorter pieces called frames. Each frame contains source and destination addresses and error-checking data so that damaged data can be detected and re-transmitted. As per the OSI model Ethernet provides services up to and including the data link layer.

Since its commercial release, Ethernet has retained a good degree of compatibility. Features such as the 48-bit MAC address and Ethernet frame format have influenced other networking protocols.

History[link]

Ethernet was developed at Xerox PARC between 1973 and 1974.^[1][2] It was inspired by ALOHAnet, which Robert Metcalfe had studied as part of his PhD dissertation.^[3] The idea was first documented in a memo that Metcalfe wrote on May 22, 1973.^[1][4] In 1975, Xerox filed a patent application listing Metcalfe, David Boggs, Chuck Thacker and Butler Lampson as inventors.^[5] In 1976, after the system was deployed at PARC, Metcalfe and Boggs published a seminal paper.^{[6][note 1]}

Metcalfe left Xerox in June 1979 to form 3Com.^[1][8] He convinced Digital Equipment Corporation (DEC), Intel, and Xerox to work together to promote Ethernet as a standard. The so-called "DIX" standard, for "Digital/Intel/Xerox" specified 10 Mbit/s Ethernet, with 48-bit destination and source addresses and a global 16-bit Ethertype-type field. It was published on September 30, 1980 as "The Ethernet, A Local Area Network. Data Link Layer and Physical Layer Specifications".^[9] Version 2 was published in November, 1982^[10] and defines what has become known as Ethernet II. Formal standardization efforts proceeded at the same time.

Ethernet initially competed with two largely proprietary systems, Token Ring and Token Bus. Because Ethernet was able to adapt to market realities and shift to inexpensive and ubiquitous twisted pair wiring, these proprietary protocols soon found themselves competing in a market inundated by Ethernet products and by the end of the 1980s, Ethernet was clearly the dominant network technology.^[1] In the process, 3Com became a major company. 3Com shipped its first 10 Mbit/s Ethernet 3C100 transceiver in March 1981, and that year started selling adapters for PDP-11s and VAXes, as well as Multibus-based Intel and Sun Microsystems computers.^[11]:9 This was followed quickly by DEC's Unibus to Ethernet adapter, which DEC sold and used internally to build its own corporate network, which reached over 10,000 nodes by 1986, making it one of the largest computer networks in the world at that time.^[12] An Ethernet adapter card for the IBM PC was released in 1982 and by 1985, 3Com had sold 100,000.^[8]

Since then Ethernet technology has evolved to meet new bandwidth and market requirements.^[13] In addition to computers, Ethernet is now used to interconnect appliances and other personal devices.^[1] It is used in industrial applications and is quickly replacing legacy data transmission systems in the world's telecommunications networks.^[14] By 2010, the market for Ethernet equipment amounted to over $16 billion per year.^[15]

Standardization[link]

Notwithstanding its technical merits, timely standardization was instrumental to the success of Ethernet. It required well-coordinated and partly competitive activities in several standardization bodies such as the IEEE, ECMA, IEC, and finally ISO.^{[citation needed]}

In February 1980, the Institute of Electrical and Electronics Engineers (IEEE) started project 802 to standardize local area networks (LAN).^[16][8]

The "DIX-group" with Gary Robinson (DEC), Phil Arst (Intel), and Bob Printis (Xerox) submitted the so-called "Blue Book" CSMA/CD specification as a candidate for the LAN specification.^[9] In addition to CSMA/CD, Token Ring (supported by IBM) and Token Bus (selected and henceforward supported by General Motors) were also considered as candidates for a LAN standard. Competing proposals and broad interest in the initiative led to strong disagreement over which technology to standardize. In December 1980, the group was split into three subgroups and standardization proceeded separate for each proposal.^[8]

Delays in the standards process put at risk the market introduction of the Xerox Star workstation and 3Com's Ethernet LAN products. With such business implications in mind, David Liddle (General Manager, Xerox Office Systems) and Metcalfe (3Com) strongly supported a proposal of Fritz Röscheisen (Siemens Private Networks) for an alliance in the emerging office communication market, including Siemens' support for the international standardization of Ethernet (April 10, 1981). Ingrid Fromm, Siemens' representative to IEEE 802, quickly achieved broader support for Ethernet beyond IEEE by the establishment of a competing Task Group "Local Networks" within the European standards body ECMA TC24. As early as March 1982 ECMA TC24 with its corporate members reached agreement on a standard for CSMA/CD based on the IEEE 802 draft.^[11]:8 Because the DIX proposal was most technically complete and because of the speedy action taken by ECMA which decisively contributed to the conciliation of opinions within IEEE, the IEEE 802.3 CSMA/CD standard was approved in December 1982.^[8] IEEE published the 802.3 standard as a draft in 1983 and as a standard in 1985.

Approval of Ethernet on the international level was achieved by a similar, cross-partisan action with Fromm as liaison officer working to integrate International Electrotechnical Commission, TC83 and International Organization for Standardization (ISO) TC97SC6, and the ISO/IEEE 802/3 standard was approved in 1984.^{[citation needed]}

Evolution[link]

Ethernet evolved to include higher bandwidth, improved media access control methods, and different physical media. The coaxial cable was replaced with point-to-point links connected by Ethernet repeaters or switches to reduce installation costs, increase reliability, and improve management and troubleshooting. Many variants of Ethernet remain in common use.

Ethernet stations communicate by sending each other data packets: blocks of data individually sent and delivered. As with other IEEE 802 LANs, each Ethernet station is given a 48-bit MAC address. The MAC addresses are used to specify both the destination and the source of each data packet. Ethernet establishes link level connections, which can be defined using both the destination and source addresses. On reception of a transmission, the receiver uses the destination address to determine whether the transmission is relevant to the station or should be ignored. Network interfaces normally do not accept packets addressed to other Ethernet stations. Adapters come programmed with a globally unique address.^{[note 2]} An Ethertype field in each frame is used by the operating system on the receiving station to select the appropriate protocol module (i.e. the Internet protocol module). Ethernet frames are said to be self-identifying, because of the frame type. Self-identifying frames make it possible to intermix multiple protocols on the same physical network and allow a single computer to use multiple protocols together.^[17] Despite the evolution of Ethernet technology, all generations of Ethernet (excluding early experimental versions) use the same frame formats^{[18][not in citation given]} (and hence the same interface for higher layers), and can be readily interconnected through bridging.

Due to the ubiquity of Ethernet, the ever-decreasing cost of the hardware needed to support it, and the reduced panel space needed by twisted pair Ethernet, most manufacturers now build Ethernet interfaces directly into PC motherboards, eliminating the need for installation of a separate network card.^[19]

Shared media[link]

10BASE5 Ethernet equipment

Ethernet was originally based on the idea of computers communicating over a shared coaxial cable acting as a broadcast transmission medium. The methods used were similar to those used in radio systems,^{[note 3]} with the common cable providing the communication channel likened to the Luminiferous aether in 19th century physics, and it was from this reference that the name "Ethernet" was derived.^[20]

Original Ethernet's shared coaxial cable (the shared medium) traversed a building or campus to every attached machine. A scheme known as carrier sense multiple access with collision detection (CSMA/CD) governed the way the computers shared the channel. This scheme was simpler than the competing token ring or token bus technologies.^{[note 4]} Computers were connected to an Attachment Unit Interface (AUI) transceiver, which was in turn connected to the cable (later with thin Ethernet the transceiver was integrated into the network adapter). While a simple passive wire was highly reliable for small networks, it was not reliable for large extended networks, where damage to the wire in a single place, or a single bad connector, could make the whole Ethernet segment unusable.^{[note 5]}

Through the first half of the 1980s, Ethernet's 10BASE5 implementation used a coaxial cable 0.375 inches (9.5 mm) in diameter, later called "thick Ethernet" or "thicknet". Its successor, 10BASE2, called "thin Ethernet" or "thinnet", used a cable similar to cable television cable of the era. The emphasis was on making installation of the cable easier and less costly.

Since all communications happen on the same wire, any information sent by one computer is received by all, even if that information is intended for just one destination.^{[note 6]} The network interface card interrupts the CPU only when applicable packets are received: The card ignores information not addressed to it.^{[note 7]} Use of a single cable also means that the bandwidth is shared, such that, for example, available bandwidth to each device is halved when two stations are simultaneously active.

Collisions corrupt transmitted data and require stations to retransmit. The lost data and retransmissions reduce throughput. In the worst case where multiple active hosts connected with maximum allowed cable length attempt to transmit many short frames, excessive collisions can reduce throughput dramatically. However, a Xerox report in 1980 studied performance of an existing Ethernet installation under both normal and artificially generated heavy load. The report claims that 98% throughput on the LAN was observed.^[21] This is in contrast with token passing LANs (token ring, token bus), all of which suffer throughput degradation as each new node comes into the LAN, due to token waits. This report was controversial, as modeling showed that collision-based networks became unstable under loads as low as 40% of nominal capacity. Many early researchers failed to understand the subtleties of the CSMA/CD protocol and how important it was to get the details right, and were really modeling somewhat different networks (usually not as good as real Ethernet).^[22]

Repeaters and hubs[link]

A 1990s network interface card supporting both coaxial cable-based 10BASE2 (BNC connector, left) and twisted pair-based 10BASE-T (8P8C connector, right)

For signal degradation and timing reasons, coaxial Ethernet segments had a restricted size. Somewhat larger networks could be built by using an Ethernet repeater. Early repeaters had only two ports, allowing, at most, a doubling of network size. Once repeaters with more than two ports became available, it was possible to wire the network in a star topology. Early experiments with star topologies (called "Fibernet") using optical fiber were published by 1978.^[23]

Shared cable Ethernet was always hard to install in offices because its bus topology was in conflict with the star topology cable plans designed into buildings for telephony. Modifying Ethernet to conform to twisted pair telephone wiring already installed in commercial buildings provided another opportunity to lower costs, expand the installed base, and leverage building design, and, thus, twisted-pair Ethernet was the next logical development in the mid-1980s.

Ethernet on unshielded twisted-pair cables (UTP) began with StarLAN at 1 Mbit/s in the mid-1980s. In 1987 SynOptics introduced the first twisted-pair Ethernet at 10 Mbit/s in a star-wired cabling topology with a central hub, later called LattisNet.^[24][25][8] These evolved into 10BASE-T, which was designed for point-to-point links only, and all termination was built into the device. This changed repeaters from a specialist device used at the center of large networks to a device that every twisted pair-based network with more than two machines had to use. The tree structure that resulted from this made Ethernet networks easier to maintain by preventing most faults with one peer or its associated cable from affecting other devices on the network.

Despite the physical star topology and the presence of separate transmit and receive channels in the twisted pair and fiber media, repeater based Ethernet networks still use half-duplex and CSMA/CD, with only minimal activity by the repeater, primarily the Collision Enforcement signal, in dealing with packet collisions. Every packet is sent to every port on the repeater, so bandwidth and security problems are not addressed. The total throughput of the repeater is limited to that of a single link, and all links must operate at the same speed.

Bridging and switching[link]

Patch cables with patch fields of two Ethernet switches

While repeaters could isolate some aspects of Ethernet segments, such as cable breakages, they still forwarded all traffic to all Ethernet devices. This created practical limits on how many machines could communicate on an Ethernet network. The entire network was one collision domain, and all hosts had to be able to detect collisions anywhere on the network. This limited the number of repeaters between the farthest nodes. Segments joined by repeaters had to all operate at the same speed, making phased-in upgrades impossible.

To alleviate these problems, bridging was created to communicate at the data link layer while isolating the physical layer. With bridging, only well-formed Ethernet packets are forwarded from one Ethernet segment to another; collisions and packet errors are isolated. Prior to learning of network devices on the different segments, Ethernet bridges (and switches) work somewhat like Ethernet repeaters, passing all traffic between segments. However, as the bridge learns the addresses associated with each port, it forwards network traffic only to the necessary segments, improving overall performance. Broadcast traffic is still forwarded to all network segments. Bridges also overcame the limits on total segments between two hosts and allowed the mixing of speeds, both of which are critical to deployment of Fast Ethernet.

In 1989, the networking company Kalpana introduced their EtherSwitch, the first Ethernet switch.^{[note 8]} This worked somewhat differently from an Ethernet bridge, where only the header of the incoming packet would be examined before it was either dropped or forwarded to another segment. This greatly reduced the forwarding latency and the processing load on the network device. One drawback of this cut-through switching method was that packets that had been corrupted would still be propagated through the network, so a jabbering station could continue to disrupt the entire network. The eventual remedy for this was a return to the original store and forward approach of bridging, where the packet would be read into a buffer on the switch in its entirety, verified against its checksum and then forwarded, but using more powerful application-specific integrated circuits. Hence, the bridging is then done in hardware, allowing packets to be forwarded at full wire speed.

When a twisted pair or fiber link segment is used and neither end is connected to a repeater, full-duplex Ethernet becomes possible over that segment. In full-duplex mode, both devices can transmit and receive to and from each other at the same time, and there is no collision domain. This doubles the aggregate bandwidth of the link and is sometimes advertised as double the link speed (e.g., 200 Mbit/s).^{[note 9]} The elimination of the collision domain for these connections also means that all the link's bandwidth can be used by the two devices on that segment and that segment length is not limited by the need for correct collision detection.

Since packets are typically delivered only to the port they are intended for, traffic on a switched Ethernet is less public than on shared-medium Ethernet. Despite this, switched Ethernet should still be regarded as an insecure network technology, because it is easy to subvert switched Ethernet systems by means such as ARP spoofing and MAC flooding.

The bandwidth advantages, the slightly better isolation of devices from each other, the ability to easily mix different speeds of devices and the elimination of the chaining limits inherent in non-switched Ethernet have made switched Ethernet the dominant network technology.^[26]

Advanced networking[link]

A core Ethernet switch

Simple switched Ethernet networks, while a great improvement over repeater-based Ethernet, suffer from single points of failure, attacks that trick switches or hosts into sending data to a machine even if it is not intended for it, scalability and security issues with regard to broadcast radiation and multicast traffic, and bandwidth choke points where a lot of traffic is forced down a single link.^{[citation needed]}

Advanced networking features in switches and routers combat these issues through means including spanning-tree protocol to maintain the active links of the network as a tree while allowing physical loops for redundancy, port security and protection features such as MAC lock down and broadcast radiation filtering, virtual LANs to keep different classes of users separate while using the same physical infrastructure, multilayer switching to route between different classes and link aggregation to add bandwidth to overloaded links and to provide some measure of redundancy.

Networking advances IEEE 802.1aq (SPB) include the use of the link-state routing protocol IS-IS to allow larger networks with shortest path routes between devices.

Varieties of Ethernet[link]

The Ethernet physical layer evolved over a considerable time span and encompasses coaxial, twisted pair and fiber optic physical media interfaces and speeds from 10 Mbit to 100 Gbit. The most common forms used are 10BASE-T, 100BASE-TX, and 1000BASE-T. All three utilize twisted pair cables and 8P8C modular connectors. They run at 10 Mbit/s, 100 Mbit/s, and 1 Gbit/s, respectively. Fiber optic variants of Ethernet offer high performance, electrical isolation and distance (tens of kilometers with some versions). In general, network protocol stack software will work similarly on all varieties.

Ethernet frames[link]

A data packet on the wire is called a frame. A frame begins with preamble and start frame delimiter, followed by an Ethernet header featuring source and destination MAC addresses. The middle section of the frame consists of payload data including any headers for other protocols (e.g., Internet Protocol) carried in the frame. The frame ends with a 32-bit cyclic redundancy check, which is used to detect corruption of data in transit.

Autonegotiation[link]

Autonegotiation is the procedure by which two connected devices choose common transmission parameters, such as speed and duplex mode. Autonegotiation was first introduced as an optional feature for 100BASE-TX, but it is also backward compatible with 10BASE-T. Autonegotiation is mandatory for 1000BASE-T.

See also[link]

	Computer networking portal
	Computer Science portal

• Gigabit Ethernet
• 10 Gigabit Ethernet
• 100 Gigabit Ethernet
• 5-4-3 rule
• AUI, GBIC, SFP, MII and PHY (chip)
• Chaosnet
• Ethernet crossover cable
• Fiber media converter
• Industrial Ethernet
• List of device bit rates
• Metro Ethernet
• Power over Ethernet
• Point-to-Point Protocol over Ethernet
• Wake-on-LAN

Notes[link]

References[link]

Further reading[link]

• Digital Equipment Corporation, Intel Corporation, Xerox Corporation (September, 1980). The Ethernet: A Local Area Network. http://portal.acm.org/citation.cfm?id=1015591.1015594.  — Version 1.0 of the DIX specification.
• "Internetworking Technology Handbook". Cisco Systems. http://docwiki.cisco.com/wiki/Ethernet_Technologies. Retrieved April 11, 2011. 

External links[link]

Wikimedia Commons has media related to: Ethernet

• IEEE 802.3 Ethernet working group
• IEEE 802.3-2008 standard

This article has multiple issues. Please help improve it or discuss these issues on the talk page. It needs additional citations for verification. Tagged since November 2007. It relies on references to primary sources or sources affiliated with the subject, rather than references from independent authors and third-party publications. Tagged since March 2010.

Laptop technicians working at stations (2000). Tagged repairs in process can be seen on lower shelves at left, and service parts in labeled boxes seen above them.

A computer repair technician is a person who repairs and maintains computers and servers. The technician's responsibilities may extend to include building or configuring new hardware, installing and updating software packages, and creating and maintaining computer networks. Computer repair technicians work in a variety of settings, encompassing both the public and private sectors. Because of the relatively brief existence of the profession, institutions offer certificate and degree programs designed to prepare new technicians, but computer repairs are frequently performed by experienced and certified technicians who have little formal training in the field.^[1]

A repair technician might work in a corporate information technology department, a central service center, or a retail computer sales environment. A public sector technician might work in the military, national security or law enforcement communities, health or public safety field, or an educational institution. Despite the vast variety of work environments, all computer technicians perform similar physical and investigative processes, including technical support. Experienced technicians might specialize in fields such as data recovery, system administration, or information systems. Some technicians are self-employed or own a firm that provides services in a regional area. Some are subcontracted as freelancers or consultants. This type of technician ranges from hobbyists and enthusiasts that volunteer or make a little side money, to those who work professionally in the field.

Computer malfunctions can range from a minor setting that is incorrect, to spyware, viruses, and as far as replacing hardware or an entire operating system. Some technicians provide on-site services usually at an hourly rate. Others can provide services off-site, where the client can drop off at the repair shop. Some have pickup and drop off services for convenience. Some technicians may also take back old equipment for recycling (In the EU, this is required under WEEE rules).

Hardware repair[link]

While computer hardware configuration varies widely, a repair technician will work with five general categories of hardware; desktop computers, laptops, servers, computer clusters and smartphones / mobile computing. Technicians also work with and occasionally repair a range of peripherals, including input devices (like keyboards, mice, and scanners), output devices (like displays, printers, and speakers), and data storage devices such as internal and external hard drives and disk arrays. Technicians involved in system administration might also work with networking hardware, including routers, switches, fiber optics, and wireless networks.

Software repair[link]

When possible, repair technicians protect the computer user's data and settings, so that after repair, the user will not have lost any data and the technician can fully use the device with little interruption, and then diagnose the problem. Addressing the issue, the technician could take action as minor as adjusting one or several settings or preferences, but could also apply more involved techniques like installing, uninstalling, or reinstalling various software packages. A reliable, but somewhat more complicated, procedure for addressing software issues is known as a restore, in which the computer's original installation image (including operating system and original applications) is reapplied to a formatted hard drive. It should be known though, that anything unique, such as settings, or personal files will be destroyed if not backed up on external media, as this reverts everything back to its original unused state.

See also[link]

Wikibooks has a book on the topic of A+ Certification

• Information systems technician
• Rework (electronics)

Notes[link]

References[link]

• Overview of job scope
• Job description from a public school district

Robert Metcalfe
Robert Metcalfe wearing the United States National Medal of Technology (2003).
Born	(1946-04-07) April 7, 1946 (age 66) Brooklyn, New York, United States.
Residence	United States
Citizenship	United States
Fields	Computer networking
Institutions	MIT, Xerox PARC, 3Com, The University of Texas at Austin.
Alma mater	MIT, Harvard University.
Doctoral advisor	Jeffrey P. Buzen
Known for	Co-invention of Ethernet.
Notable awards	National Medal of Technology, IEEE Medal of Honor, IEEE Alexander Graham Bell Medal, ACM Grace Murray Hopper Award, Computer History Museum Fellow Awards.

Robert Melancton Metcalfe (born April 7,^[1] 1946 in Brooklyn, New York) is an electrical engineer from the United States who co-invented Ethernet, founded 3Com and formulated Metcalfe's Law. As of January 2006^[update], he is a general partner of Polaris Venture Partners. Starting in January 2011, he holds the position of Professor of Electrical Engineering and Director of Innovation at The University of Texas at Austin.^[2]

Early life[link]

In 1964, Metcalfe graduated from Bay Shore Public High School. He graduated from MIT in 1969 with two B.S. degrees, one in Electrical Engineering and the other in Industrial Management from the MIT Sloan School of Management. He then went to Harvard for graduate school, earning his M.S. in 1970.

Career[link]

While pursuing a doctorate in computer science, Metcalfe took a job with MIT's Project MAC after Harvard refused to let him be responsible for connecting the school to the brand-new ARPAnet. At MIT's Project MAC, Metcalfe was responsible for building some of the hardware that would link MIT's minicomputers with the ARPAnet. Metcalfe was so enamored with ARPAnet, he made it the topic of his doctoral dissertation. However, Harvard flunked him. His inspiration for a new dissertation came while working at Xerox PARC where he read a paper about the ALOHA network at the University of Hawaii. He identified and fixed some of the bugs in the AlohaNet model and made his analysis part of a revised thesis, which finally earned him his Harvard PhD in 1973.^[3]

Metcalfe was working at Xerox PARC in 1973 when he and David Boggs invented Ethernet, a standard for connecting computers over short distances. Metcalfe identifies the day Ethernet was born as May 22, 1973, the day he circulated a memo titled "Alto Ethernet" which contained a rough schematic of how it would work. "That is the first time Ethernet appears as a word, as does the idea of using coax as ether, where the participating stations, like in AlohaNet or ARPAnet, would inject their packets of data, they'd travel around at megabits per second, there would be collisions, and retransmissions, and back-off," Metcalfe explained. Boggs identifies another date as the birth of Ethernet: November 11, 1973, the first day the system actually functioned.^[4]

In 1979, Metcalfe departed PARC and founded 3Com, a manufacturer of computer networking equipment. In 1980 he received the Association for Computing Machinery Grace Murray Hopper Award for his contributions to the development of local networks, specifically Ethernet. In 1990 Metcalfe lost a boardroom skirmish at 3Com in the contest to succeed Bill Krause as CEO. The board of directors chose Eric Benhamou to run the networking company Metcalfe had founded in his Palo Alto apartment in 1979. Metcalfe left 3Com and began a 10 year stint as a publisher and pundit, writing an Internet column for InfoWorld. He became a venture capitalist in 2001 and is now a General Partner at Polaris Venture Partners. He is a director of Pop!Tech, an executive technology conference he cofounded in 1997. He has recently been working with Polaris-funded startup Ember to work on a new type of energy grid, Enernet.

In November 2010 Metcalfe was selected to lead innovation initiatives at The University of Texas at Austin Cockrell School of Engineering. He began his appointment in January 2011.^[5]

Awards[link]

Metcalfe was awarded the IEEE Medal of Honor in 1996 for "exemplary and sustained leadership in the development, standardization, and commercialization of Ethernet."^[6]

Metcalfe received the National Medal of Technology from President Bush in a White House ceremony on March 14, 2003, "for leadership in the invention, standardization, and commercialization of Ethernet", having been selected for the honor in 2003.^[7] In May 2007, along with 17 others, Metcalfe, was inducted to the National Inventors Hall of Fame in Akron, Ohio, for his work with Ethernet technology.^[8]

In October 2008 Metcalfe received the Fellow Award from the Computer History Museum.^[9]

Incorrect predictions[link]

Outside of his technical achievements, Metcalfe is perhaps best known for his 1995 prediction that the internet would suffer a catastrophic collapse the following year; he promised to eat his words if it did not. During his keynote speech at the Sixth WWW International Conference in 1997, he took a printed copy of his column that predicted the collapse, put it in a blender with some liquid and then consumed the pulpy mass.^[10][11] This was after he tried to eat his words in the form of a very large cake, but the audience strongly protested.

During an event where he talked about predictions at the Eighth International World Wide Web Conference in 1999, a participant asked: what is the bet?. He stated that there was no bet as he was not ready to eat another column.

Metcalfe is also known for his harsh criticism of open source software, and Linux in particular, predicting that the latter would be obliterated after Microsoft released Windows 2000:

The Open Source Movement's ideology is utopian balderdash [... that] reminds me of communism. [...] Linux [is like] organic software grown in utopia by spiritualists [...] When they bring organic fruit to market, you pay extra for small apples with open sores – the Open Sores Movement. When [Windows 2000] gets here, goodbye Linux.^[12]

He later recanted to some extent, saying in a column two weeks later:

I am ashamed of myself for not resisting the temptation to take cheap shots in my column ... I should not have fanned the flames by joking about the Open Sores initiative.^[13]

He also predicted that wireless networking would die out in the mid 1990s.:

After the wireless mobile bubble bursts this year, we will get back to stringing fibers ... bathrooms are still predominantly plumbed. For more or less the same reason, computers will stay wired.^[14]

Selected publications[link]

• "Packet Communication", MIT Project MAC Technical Report MAC TR-114, December, 1973 (a recast version of Metcalfe's Harvard dissertation)
• "Zen and the Art of Selling", Technology Review, May/June 1992^[15]

See also[link]

• Metcalfe's Law

References[link]

External links[link]

Wikimedia Commons has media related to: Robert Metcalfe

• Robert Metcalfe on Twitter
• An interview with Robert Metcalfe
• Interview ITworld
• A more detailed interview
• Video - The History of Ethernet
• Why IT Matters
• Video Interview of Robert Metcalfe on March 10, 2009 at the Computer History Museum