Method and apparatus for providing multiple multicast communication

Abstract

An ATM destination switch includes an ATM layer device coupled to a physical layer device. The ATM layer device includes a ATM layer interface which receives incoming ATM cells, a processor which is typically with an associated translation RAM, and an ATM layer to physical layer interface. The processor decodes the incoming ATM cell to obtain a VPI/VCI, and provides additional routing information (session number) for the cell for multicast purposes. The cell with the additional routing information is forwarded to the physical layer device which has a header processor, a multicast indicator storage table, preferably in the form of a bit map, for storing output line indications by session number, and a plurality of ATM line output interfaces. The header processor receives the cell with the additional routing information, reads the additional routing information, accesses the multicast indicator storage table based on the additional routing information to determine to which output lines the cell is to be provided, and controls the copying of the cell for each output line so that it may be received at multiple destinations. Thus, an incoming cell which is to be multicast to multiple users connected to the physical layer side of the switch will be multicast to the multiple users using the single VPI/VCI chosen for the local multicast.