On Distributed Communications Series
V. History, Alternative Approaches, and Comparisons
Contents
Preface
Summary
I. Introduction
II. The Distributed Network Concept
III. Early History
Mouse in a Maze
In 1952, Claude Shannon demonstrated[1] a machine which was a model of a mouse able to find its way out of a maze (see Figs. 6 and 7). Shannon showed that a relatively simple routing policy could be used to have the mouse examine the entire maze to find the piece of "cheese."
Fig. 7--Shannon's Electrical Mouse[2]
Shannon's mouse was not a distributed system, as his controls were centralized, but he did use a "heuristic" routing doctrine. There was no guarantee that his mouse would ever traverse the entire maze, but the probability that it would was near unity.
Barnstable
In the Final Report[3] of MIT's Project Barnstable, another mouse-in-a-maze technique was suggested whereby a mouse could find its way out of a maze by marking each maze function point (node) traversed with a "chalk mark."
This technique appears to have the limitation that a message must store within itself the identity of all switching nodes traversed. Alternatively, each switching node would have to store a long history of recent traffic. In such a case, it would be necessary to compare each new message with previously encountered traffic to determine which paths have already been tried.
Voice Relay
In 1955, Frank Collbohm of RAND suggested that traffic could be relayed from broadcast station to broadcast station to provide an emergency means for transmitting extremely urgent messages. The routing was to be handled by human judgment.
[1]Eighth Conference of the Josiah Macy, Jr., Foundation, New York.
[2]Figure courtesy of Shannon, Claude, "Maze Solving Machines," in Cybernetics, Heinz von Foerster (ed.), Josiah Macy, Jr., Foundation, New York, 1952.
[3]Barnstable Summer Study, "A Study of Communications Theory Applied to Military Communications Systems," (U) MIT Research Laboratory for Electronics, Cambridge, Massachusetts, October 30, 1958.
IV. Specific Hardware Proposals
V. Conclusions
Appendix A. Summary Charts
Appendix B. The DDD System
List of Publications in the Series