Paul Baran

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Paul Baran (born April 29, 1926^[1]) was one of the three inventors of packet-switched networks, along with Donald Davies and Leonard Kleinrock. He was born in Grodno (then Poland) and his family moved to Philadelphia in 1928. Baran did undergraduate work at Drexel University, obtained his Masters degree in Engineering from UCLA in 1959 and began working for the RAND Corporation in the same year.

Similar ideas for a distributed data network were being independently pursued by Donald Davies from the National Physical Laboratory in the UK, although Davies was primarily concerned with the problem of resource-sharing rather than Baran's focus on military issues.

Contents 1 Packet Switched Network Design 1.1 Selling the Idea 2 Later Work 3 References 4 External links

[edit] Packet Switched Network Design

While working at the RAND Corporation, Paul Baran was assigned the task of designing a "survivable" communications system that could maintain communication between end points in the face of damage from nuclear attack. Baran's previous work with emergency communication over AM radio networks prepared his thought process for this task, which included the notion of a distributed relay node architecture.

Using 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.

After proving survivability Baran and his team needed to show proof of concept for this design such that it would be able to 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"^[2]. 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.

[edit] Selling the Idea

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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.

As a result of President Eisenhower's Defense Reorganization Act of 1958, there was a major shift in leadership in the Pentagon around the time Baran's work was accepted by the US Air Force and DoD for implementation and testing. When Baran discovered an older Navy admiral would oversee the project he decided the project would be better off sitting on the shelf as reference material, claiming that an 'old analog guy' couldn't grasp what it was the project aimed to accomplish, and thus would likely fail from lack of understanding.

Around the same time when ARPA was developing the idea of an inter-networked set of terminals to share computing resources, among the number of reference materials considered was Paul Baran and the RAND Corporation's On Distributed Communications volumes. The ARPANET was never intended to be a survivable communications network, but some still maintain the myth that it was. Instead, the resilience feature of a packet switched network that uses link-state routing protocols is something we enjoy today in some part from the research done to develop a network that could survive a nuclear attack.

[edit] Later Work

Baran also provided a spark of invention to four other important networking technologies. He was involved in the origin of the packet voice technology developed by StrataCom at its predecessor, Packet Technologies. This technology led to the first commercial pre-standard ATM product. He was also involved with the discrete multitone modem technology developed by Telebit, which was one of the roots of Orthogonal frequency-division multiplexing which is used in DSL modems. Paul Baran founded Metricom, the first wireless Internet company, which deployed Ricochet, the first public wireless mesh networking system. He also founded Com21, an early cable modem company. In all cases, he provided early ideas and gave credibility to strong groups of developers who then took those ideas far beyond Baran's original spark.

Paul Baran also extended his work in packet switching to wireless-spectrum theory, developing what he called "kindergarten rules" for the use of wireless spectrum.

In addition to his innovation in networking products, he is also credited with inventing the metal detector used in airports.

[edit] References

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• ibiblio.org entry

[edit] External links

• Paul Baran Invents Packet Switching – Living Internet
• 44-page oral history interview with Paul Baran. Charles Babbage Institute University of Minnesota, Minneapolis. Baran describes his working environment at RAND, as well as his initial interest in survivable communications, the evolution of his plan for distributed networks, the objections he received, the writing and distribution of his eleven-volume work, "On Distributed Communications." Baran discusses his interaction with the group at ARPA who were responsible for the later development of the ARPANET.
• Founding Father Wired, Issue 9.03 Mar 2001, (interview with Paul Baran, exploring the background to Baran's work at RAND on survivable networks).
• The Influence of Paul Baran on the Development of the Internet (Academic Paper written by B. Vuyk)
• Paul Baran, On Distributed Communications, 1964
• Wireless Communications and Computing at a Crossroads, Journal on Telecommunications & High Technology Law, Vol. 3, No. 2, p. 239, 205 (describing Paul Baran's development of packet switching and its application to wireless computing).
• Transcript of a keynote address he gave in 2000 including a photo
• Reliable Digital Communications Systems Using Unreliable Network Repeater Nodes

Awards
Preceded by Gerald R. Ash and Billy B. Oliver	IEEE Alexander Graham Bell Medal 1990	Succeeded by C. Chapin Cutler, John O. Limb and Arun Netravali