System architecture for linking channel banks of a data communication system

A single switch fabric-based, multi-channel bank digital subscriber line access multiplexer includes a master channel bank containing a master switch module in which the switch fabric and a downstream-directed traffic scheduler reside, and one or more expansion channel banks that are linked with the master channel bank by way of upstream and downstream communication links. Distributed among the channel banks are respective policing mechanisms and cell rate control mechanisms that control upstream-directed communications from line card ports of each expansion channel bank to the switch fabric. Downstream data transmissions are locked to network timing, and are scheduled by a centralized scheduling mechanism resident in the master channel bank.