A study of non blocking multicast switching networks

The paper studies three-stage switching networks capable of routing point-to-multipoint connections. Strict-sense non blocking operation is addressed and, in particular, the necessary and sufficient condition for a three-stage switching network to be strictly non blocking when it is offered point-to-multipoint traffic is derived. This condition is given as a function both of the minimum and the maximum number of network outlets addressed by each connection. In this respect, the work extends the well known Clos´ result, giving the necessary and sufficient condition for a three-stage switching network to be strictly non blocking when it is offered point-to-point traffic. The complexity of a three-stage network is lower than that of a crossbar of equal size only for small values of the maximum admissible fanout of the incoming connections