System and method for multicasting packets in a subscriber network

A plurality of multimodulators in a digital network that receive at least one transport stream, each of the plurality of multimodulators transmit all or a portion of the at least one transport stream, each of the plurality of multimodulators comprising:

• an input port that receives the at least one transport stream, each transport stream having a plurality of packets included therein;
• a processor in communication with the input port, the processor determines which packets of the at least one transport stream are multicast and unicast packets, wherein a multicast packet is a packet that is transmitted from a plurality of modulators, and a unicast packet is transmitted from only one of the plurality of modulators, the processor for appending a data unit header to each packet, wherein the data unit header associates each packet to at least one modulator for transmission;
• a plurality of unicast buffers for storing unicast packets and a multicast buffer for storing multicast packets, each unicast buffer being associated with a respective modulator, each buffer for receiving a packet according to the data unit header thereof;
• and
• the plurality of modulators in communication with the processor, each modulator requests a buffered packet, modulates and transmits the requested packet therefrom, each multicast packet being copied from the multicast buffer for transmission depending on the number of transmitting modulators identified in the data unit header thereof.

A multimodulator in a broadband delivery system of digital network that receives at least one transport stream, the multimodulator comprising:

• an input port receives the at least one transport stream, each transport stream having a plurality of data packets included therein;
• a packet handler that appends a data unit header to each data packet that has been determined is to be retransmitted from the multimodulator to provide a data unit packet, the data unit header including information identifying one or more of the plurality of modulators from which the packet is to be transmitted;
• memory comprising at least one unicast buffer and a multicast buffer, the packet handler storing each data unit packet in a corresponding one of the at least one unicast buffer and the multicast buffer according to the data unit header appended thereto;
• and
• a plurality of modulators that request a buffered packet, modulate and transmit the requested packet therefrom, the packet handler retrieving a given data unit packet from one of the at least one unicast buffer and the multicast buffer in response to a request for a data packet, at least a payload portion of the retrieved data unit packet being stored in an output buffer associated with each of the plurality of modulators from which the packet is to be transmitted according to the information in the data unit header of the retrieved data unit packet,
• wherein, if the retrieved data unit packet is a multicast packet, at least the payload portion of the multicast packet retrieved from the multicast buffer is copied from the multicast buffer for transmission depending on the number of modulators identified in the data unit header thereof.