Blocking probability of three-stage multicast switches

In this paper, an analytical model for the evaluation of the blocking probability of a three stage STM switch in presence of multicast is presented. The basic characteristics of this model are: (i) the elementary switches can assume any size; (ii) multicast connections can be characterised by any fan-out distribution; (iii) both single request and additive request scenarios are analysed. Moreover, three network operation alternatives are analysed, i.e. multicasting is carried-out in: (a) the first and the third stages; (b) the second and the third stages; (c) all the three stages. The model uses a mixed approach derived from approaches proposed by Lee (1955)and Jacobeus (1950). The analytical results are compared with those arising from simulation. The good accordance of the two series of results demonstrates the soundness of the model assumptions.