Paul Baran (1926,
Grodno–2011) was a Polish American engineer who was a pioneer in the development of computer networks. He invented packet switching techniques, and went on to start several companies and develop other technologies that are an essential part of the Internet and other modern digital communication.
Paul Baran was born in Grodno, Second Polish Republic (now part of Belarus) on April 29, 1926.[1][2] He was the youngest of three children in a Jewish family,[3] with the Yiddish given name "Pesach". His family moved to the United States on May 11, 1928,[4] settling in Boston and later in Philadelphia, where his father, Morris "Moshe" Baran (1884–1979), opened a grocery store. He graduated from Drexel University in 1949 (then called Drexel Institute of Technology), with a degree in electrical engineering. He then joined the Eckert-Mauchly Computer Company, where he did technical work on UNIVAC models, the first brand of commercial computers in the USA.[5] In 1955 he married Evelyn Murphy, moved to Los Angeles, and worked for Hughes Aircraft on radar systems. He obtained his Masters degree in engineering from UCLA in 1959, with advisor Gerald Estrin while taking night classes. His thesis was on character recognition.
After joining the RAND Corporation that same year, Baran took on the task of designing a "survivable" communications system that could maintain communication between end points in the face of damage from nuclear weapons.[6] At the time of the Cold War, most American military communications used High Frequency connections which could be put out of action for many hours by a nuclear attack. Baran decided to automate RAND director Franklin R. Collbohm's previous work with emergency communication over conventional AM radio networks and showed that a distributed relay node architecture could be survivable. The Rome Air Development Center soon showed that the idea was practicable.[7]
Using the mini-computer technology of the day, Baran and his team developed a simulation suite to test basic connectivity of an array of nodes with varying degrees of linking. That is, a network of n-ary degree of connectivity would have n links per node. The simulation randomly 'killed' nodes and subsequently tested the percentage of nodes who remained connected. The result of the simulation revealed that networks where n ≥ 3 had a significant increase in resilience against even as much as 50% node loss. Baran's insight gained from the simulation was that redundancy was the key.[8] His first work was published a RAND report in 1960,[9] with more papers generalizing the techniques in the next two years.[10]
After proving survivability Baran and his team needed to show proof of concept for this design such that it could be built. This involved high level schematics detailing the operation, construction and cost of all the components required to construct a network that leveraged this new insight of redundant links. The result of this was one of the first store-and-forward data layer switching protocols, a link-state/distance vector routing protocol, and an unproved connection-oriented transport protocol. Explicit detail of these designs can be found in the complete series of reports "On Distributed Communications", published by RAND in 1964.[11] The design flew in the face of telephony design of the time, placing inexpensive and unreliable nodes at the center of the network, and more intelligent terminating 'multiplexer' devices at the endpoints. In Baran's words, unlike the telephone company's equipment, his design didn't require expensive "gold plated" components to be reliable.
After the publication of "On Distributed Communications'", Paul Baran presented the findings of his team to a number of audiences, including AT&T engineers (not to be confused with Bell labs engineers, who at the time provided Paul Baran with the specifications for the first generation of T1 circuit which he used as the links in his network design proposal). In subsequent interviews Baran mentions how his idea of non-dedicated physical circuits for voice communications were scoffed at by the AT&T engineers who at times claimed that Baran simply did not understand how voice telecommunication worked.[12]
Leonard Kleinrock developed a theoretical basis for the operation of packet networks in his Ph.D. thesis in 1961. Baran used the term "message blocks" for his units of communication. Donald Davies at the National Physical Laboratory in the United Kingdom was the first to use the term "packet switching" in 1965, and apply the concept to a general-purpose computer network. Davies' key observation was that computer network traffic was inherently "bursty" with periods of silence, compared with relatively constant telephone traffic.[1][13]
In 1969 when the US Defense Advanced Research Projects Agency (ARPA) was developing the idea of an inter-networked set of terminals to share computing resources, among the number of reference materials considered was Baran and the RAND Corporation's "On Distributed Communications" volumes.[1] The resiliency of a packet switched network that uses link-state routing protocols used on the Internet stems in some part from the research to develop a network that could survive a nuclear attack.
In 1968 Baran was a founder of the Institute for the Future, and then involved in other networking technologies developed in Silicon Valley. He participated in a review of the NBS proposal for a Data Encryption Standard in 1976, along with Martin Hellman and Whitfield Diffie of Stanford University.[15] In the early 1980s, Baran founded PacketCable, Inc, "to support impulse-pay television channels, locally generated videotex, and packetized voice transmission".[16][17] PacketCable (also known as Packet Technologies) spun off StrataCom to commercialize his packet voice technology for the telephony market. This technology led to the first commercial pre-standard Asynchronous Transfer Mode product. He founded Telebit after conceiving its discrete multitone modem technology in the mid-1980s. This was one of the first commercial products to use Orthogonal frequency-division multiplexing, which was later widely deployed in DSL modems and Wi-Fi wireless modems. In 1985, Baran founded Metricom, the first wireless Internet company, which deployed Ricochet,[2] the first public wireless mesh networking system. In 1992, he also founded Com21, an early cable modem company.[5] Following Com21, Baran founded and was president of GoBackTV, which specializes in personal TV and cable IPTV infrastructure equipment for television operators.[18] Most recently he founded Plaster Networks, providing an advanced solution for connecting networked devices in the home or small office through existing wiring.[19]
Baran extended his work in packet switching to wireless-spectrum theory, developing what he called "kindergarten rules" for the use of wireless spectrum.[20]
In addition to his innovation in networking products, he is also credited with inventing the first metal detector, a doorway gun detector.[5][21]
He received an honorary doctorate when he gave the commencement speech at Drexel in 1997.
Baran died in Palo Alto, California at the age of 84 on March 26, 2011,[1][23] due to complications from lung cancer.[14] Upon his death James Thomson, the president of RAND stated that "Our world is a better place for the technologies Paul Baran invented and developed, and also because of his consistent concern with appropriate public policies for their use."[23] One of the fathers of the internet, Vinton Cerf, stated that "Paul wasn't afraid to go in directions counter to what everyone else thought was the right or only thing to do."[14] According to Paul Saffo, Baran also believed that innovation was a "team process" and he didn't seek credit for himself.[21] On hearing news of his death, Robert Kahn, co-inventor of the Internet, said: "Paul was one of the finest gentlemen I ever met and creative to the very end."
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