Abstract: An apparatus in a digital network receives digital packets, such as MPEG packets, included in at least one input transport stream and outputs a plurality of modulated output transport streams. The apparatus determines whether the input transport streams include packets that are for multicasting from a plurality of the modulators included within the apparatus. The apparatus also determines whether the input transport streams include unicast packets that are transmitted from only one of the output modulators of the apparatus. The apparatus identifies the unicast and multicast packets of the input transport streams and associates a modulator for each unicast packet. The associated modulator of a unicast packet is the particular modulator from which the packet is modulated and transmitted. The apparatus also associates a plurality of modulators with each multicast packet, wherein the associated plurality of modulators are the modulators from which the multicast packet is transmitted.

Abstract: An interface is provided for interfacing at least one information stream with at least one modulator in the headend or hub of a broadband communications system. The interface allows for separating the media access control function from the modulator. By updating timing references, variable delays are handled appropriately.