Paul Baran

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Lore & Background

Paul Baran was born Pesach Baran on April 29, 1926, in Grodno, then part of the Second Polish Republic. His Lithuanian Jewish family moved to the United States on May 11, 1928, settling in Boston and later Philadelphia, where his father, Morris 'Moshe' Baran (1884–1979), opened a grocery store. Baran graduated from Drexel University (then Drexel Institute of Technology) in 1949 with a degree in electrical engineering, then joined the Eckert-Mauchly Computer Company, doing technical work on UNIVAC models. In 1955 he married Evelyn Murphy, moved to Los Angeles, and worked for Hughes Aircraft on radar data processing systems. He obtained his master's degree in engineering from UCLA in 1959, with advisor Gerald Estrin while taking night classes; his thesis was on character recognition. Baran initially stayed on at UCLA to pursue a doctorate but a heavy travel and work schedule forced him to abandon his doctoral work. After joining the RAND Corporation in 1959, 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 during the Cold War. He 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. Using minicomputer technology, Baran and his team developed a simulation suite to test basic connectivity of an array of nodes with varying degrees of linking. The simulation randomly 'killed' nodes and subsequently tested the percentage of nodes that remained connected. The result revealed that networks in which 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. His first work was published as a RAND report in 1960, with more papers generalizing the techniques in the next two years. The complete series of reports, 'On Distributed Communications,' was published by RAND in 1964, detailing 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. Baran's design placed 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 did not require expensive 'gold plated' components to be reliable. Fundamental to the scheme was the division of the information into 'blocks' before they were sent out across the network. After publication, Baran presented his findings to AT&T engineers, who scoffed at his idea of non-dedicated physical circuits for voice communications, at times claiming that Baran simply did not understand how voice telecommunication worked. Donald Davies, at the National Physical Laboratory in the United Kingdom, also thought of the same idea and implemented a trial network. While Baran used the term 'message blocks,' Davies used the term 'packets.' Davies's work, not Baran's, initially caught the attention of the developers of ARPANET at the Symposium on Operating Systems Principles in October 1967. Baran was happy to acknowledge that Davies had come up with the same idea independently. In an e-mail to Davies, he wrote: 'You and I share a common view of what packet switching is all about, since you and I independently came up with the same ingredients.' In 1969, when ARPA started implementing the idea of an internetworked set of terminals to share computing resources, the reference materials that they considered included Baran and the RAND Corporation's 'On Distributed Communications' volumes. In 1968, Baran was a founder of the Institute for the Future. In 1971, he predicted the development of household email, estimating potential revenue for such services to be $707 million by 1989. In the early 1980s, Baran founded PacketCable, Inc, 'to support impulse-pay television channels, locally generated videotex, and packetized voice transmission.' PacketCable, also known as Packet Technologies, spun off StrataCom to commercialize his packet voice technology for the telephony market, leading to the first commercial pre-standard Asynchronous Transfer Mode product. He founded Telebit after conceiving its discrete multitone modem technology in the mid-1980s, one of the first commercial products to use orthogonal frequency-division multiplexing, later widely deployed in DSL modems and Wi-Fi wireless modems. In 1985, Baran founded Metricom, the first wireless Internet company, which deployed Ricochet, the first public wireless mesh networking system. In 1992, he also founded Com21, an early cable modem company. After Com21, Baran founded and was president of GoBackTV, which specializes in personal TV and cable IPTV infrastructure equipment for television operators. Later, he founded Plaster Networks, providing an advanced solution for connecting networked devices in the home or small office through existing wiring. Baran extended his work in packet switching to wireless-spectrum theory, developing what he called 'kindergarten rules' for the use of wireless spectrum. He is also credited with inventing the first doorway gun detector. 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 from complications caused by lung cancer. Upon his death, RAND President James Thomson stated, '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.' One of the fathers of the Internet, Vinton Cerf, stated, 'Paul wasn't afraid to go in directions counter to what everyone else thought was the right or only thing to do.'

Reader's Guide

Paul Baran's significance lies in his independent invention of packet switching, the foundational technology for modern data communications. His work at RAND on survivable networks, motivated by Cold War concerns, produced a distributed architecture that routed around damage by dividing data into blocks sent over redundant links. This design directly influenced the resilience of the Internet's link-state routing protocols. Baran's later entrepreneurial ventures commercialized packet voice, DSL-like modems, wireless mesh networks, and cable modem systems, embedding his innovations into everyday digital infrastructure. His contributions are recognized by historians and the U.S. National Inventors Hall of Fame, alongside Donald Davies, as originating digital packet switching. Baran also predicted household email in 1971 and participated in reviews of the Data Encryption Standard. His legacy is a network design philosophy that prioritized redundancy and decentralization over expensive, centralized reliability.

Did You Know?

• Baran's simulation showed that networks with at least three links per node remained resilient even with 50% node loss.
• He predicted household email in 1971, estimating $707 million in revenue by 1989.
• Baran invented the first doorway gun detector.
• He founded Metricom in 1985, the first wireless Internet company, which deployed Ricochet, the first public wireless mesh networking system.
• Baran's discrete multitone modem technology at Telebit was a precursor to DSL and Wi-Fi.