Application of Breakdown Devices to Large Multistage Switching Networks

Switching networks, as discussed in this paper, comprise the interconnection facility for call traffic in a telephone switching system. This definition serves to exclude from consideration the numerous other components in the switching system, including the memory, logic, sensing and controlling elements that are required. This paper is concerned primarily with that large aggregation of switches which provides the desired voice frequency communication channels among telephone customers. Moreover, the discussion is limited to space-division electronic switching networks, excluding both electromechanical switching in its many forms and time-division electronic switching. Since the advent of machine switching, a rapid evolution has taken place in the organization and control of multistage switching networks. This has led to the development of a succession of switching systems, each of which depended upon the nature of the chosen switching ele1421 1422 TIIE BELL SYSTEM TECHNICAL JOURNAL, NOVEMBER 1 9 5 8