Abstract: A multicast switch fabric is described wherein blocking of desired signal paths is handled by storing a cell to be transmitted through the fabric at a buffer at an input port to the fabric and attempting to retransmit the cell through the fabric until the cell is successfully transmitted, or a maximum number of retries at transmission is reached. Each switch element in the fabric has a block register which stores information as to whether or not a request path including that element is blocked, the block signals being fed back to the input port to indicate whether or not cell transmission has been successful. A 2.times.2 switch element is described wherein header information from the cell is decoded in two subfields, one field determining the number of copies to be replicated in the switch and a second field determining if the cell is to be fully replicated at each subsequent stage of the fabric.