Many applications of ATM networks require the multicast function, which sends the same packet to a group of destinations. This paper proposes an algorithm for multicast routing in ATM networks. We define the network cost of a routing as the combination of the cost of establishing connections, the cost of overall bandwidth and the cost of overall switchings. Our routing algorithm works on the original topology of ATM networks with physical switches and physical links, and considers the different switching functionalities of VP (virtual path) switches and VC (virtual channel) switches in the networks. It generates an optimal multicast routing with the minimal overall network cost. Simulations have been done to compare the quality of the routing generated by our algorithm with those of other major algorithms.
