In this paper, we present a model for computing the cost of implementing Banyan
networks. We limit our interest in Banyan networks which are used in ATM switching fabrics
and are build in VLSI. The cost is given as a function of the characteristics of the network (i.e.
length of buffers, speed of links, etc.). It is well-known that the implementation cost must be
related to the performance of the network. The choices, that the designer may have, impact both
the performance and the cost. We demonstrate the case where a slight increase in performance
implies a great increase in cost (in that case it is not cost effective to build a better switching
network), and of course the reverse, i.e., the case where a decrease in cost implies a degradation
of the performance of the switch.