The beginnings of packet switching: some underlying concepts

This article was written for a seminar held on the occasion of the Franklin Institute\´s 2001 Bower Award and Prize for the Achievement in Science to the author "for his seminal invention of packet switching - the foundation of modern communications networks and, in particular the Internet." It describes the author\´s work 40 years ago focusing on the rationale creating the key concepts of packet switching. The article considers the development of each of a series of about 20 essential concepts. For example, it examines such subjects as the degree of redundancy to achieve any desired level of survivability; the necessity to chop data streams into small blocks; what information had to be appended to these blocks to allow the each block to find its own way through the network; why it was necessary for each network element to operate at an independent data rate; why all signals had to be converted to digital, and so on. It describes the "why" as well as the "how" of packet switching works