Packet Switched Network Design
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 RAND report in 1960, with more papers generalizing the techniques in the next two years.
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. 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.
Read more about this topic: Paul Baran
Famous quotes containing the words packet, switched, network and/or design:
“we know our end
A packet of worm-seed, a garden of spent tissues.”
—Allen Tate (1899–1979)
“When I am on a stage, I am the focus of thousands of eyes and it gives me strength. I feel that something, some energy, is flowing from the audience into me. I actually feel stronger because of these waves. Now when the play’s done, the eyes taken away, I feel just as if a circuit’s been broken. The power is switched off. I feel all gone and empty inside of me—like a balloon that’s been pricked and the air’s let out.”
—Lynn Fontanne (1887–1983)
“A culture may be conceived as a network of beliefs and purposes in which any string in the net pulls and is pulled by the others, thus perpetually changing the configuration of the whole. If the cultural element called morals takes on a new shape, we must ask what other strings have pulled it out of line. It cannot be one solitary string, nor even the strings nearby, for the network is three-dimensional at least.”
—Jacques Barzun (b. 1907)
“Westerners inherit
A design for living
Deeper into matter—
Not without due patter
Of a great misgiving.”
—Robert Frost (1874–1963)