Paul Baran (1926–2011) was a Polish American engineer who was a pioneer in the development of computer networks. He was one of the three earliest researchers of 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.
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. 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.
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. His first work was published a a RAND report in 1960, with more papers generalizing the techniques in the next two years.
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