Comparison of Call Gapping and Percent Blocking for Overload Control in Distributed Switching Systems and in Telecommunications Networks

Two overload control techniques are compared, percent blocking and call gapping, which have been used in distributed switching systems and in telecommunications networks. A "percent blocking throttle" blocks an arrival with a given probability. A "call gapping throttle" closes for a set time interval, after which, the next job to arrive is allowed through, and the throttle again closes, repeating the cycle. The two throttle schemes are compared on nine criteria, seven of which concern robustness. The results are useful in the design of practical, effective overload controls.