An architecture for providing high-speed access over frequency-division multiplexed (FDM) channels allows transmission of ethernet frames and/or other data across a cable transmission network or other form of FDM transport. The architecture involves downstream and upstream FDM multiplexing techniques to allow contemporaneous, parallel communications across a plurality of frequency channels. Each downstream data flow is fragmented into individual octets that are multiplexed into MPEG packets. An MPEG packet may carry the octets for a plurality of individual data flows. Furthermore, the MPEG packets may be frequency-division multiplexed across and may be contemporaneously communicated over a plurality of frequency channels. Also, the octets from a data flow do not necessarily have to use consecutive octets in an MPEG packet. Instead, consecutive octets in an MPEG packet may carry information for two different data flows. Thus, in an MPEG packet there may be intervening octets that might be allocated to other data flows between the octets of an ethernet frame or other type of data from one data flow. In addition, the data flows carried in MPEG packets may support one or a plurality of client devices. Therefore, an MPEG packet may be used to time-division multiplex multiple data flows to one or a plurality of client devices.