Analysis of Delay in Mathematical Switching Models for Data Systems

Switching centers can be used to link together communication lines for the transmission of data between a variety of business machines and computers. Due to randomness in the required interconnections a switching center may occasionally not find an idle line to a particular receiving station, so that a delay can occur. More than one method can be followed when a switching center finds all lines to a receiving station busy. Some switching models appear to obtain lines to the addressed receiving stations in a shorter time than other switching models. This means that with one switching model a given delay requirement can be met with fewer lines than with another switching model. This is not to say that the model which would render a given grade of service with the least number of lines also is the most desirable from an economic point of view, because delay is only one factor which enters into the choice between data switching systems. Components of a switching system, such 709 710 THE BELL