A copy network with shared buffers for large multicast ATM switches

A new architecture for the copy network which is an integral part of multicast asynchronous transfer mode (ATM) switches is proposed. The new architecture makes use of the property that the Broadcast Banyan Network (BBN) is non-blocking if the active inputs are cyclically concentrated and the outputs are monotone. In the new architecture, by employing a token ring reservation scheme, the outputs of the copy network are reserved before a multicast cell is replicated. By the new copy principle, the number of copies requested by a multicast call is not limited by the size of the copy network, so that very large multicast switches can be configured in a modular fashion. The sequence of cells is preserved in the new structure. Though physically separated, buffers within the copy network are completely shared, so that the throughput can reach 100%, and the cell delay and the cell loss probability can be made very small