FLAG FIELD-BASED ROUTING MECHANISM FOR FIBER OPTIC TELECOMMUNICATION SYSTEM EMPLOYING STS-BASED TRANSMISSION FORMAT CONTAINING ASYNCHRONOUS TRANSFER MODE CELLS

摘要

A two-stage cell routing filter mechanism employs a customer premisesassociated flag bit field (133) in ATM data cells being serially transmittedfrom a host digital terminal's data transport path through an optical fiber(22) to a downstream optical network unit (23) associated with a plurality ofcustomer premises equipments (40). The first stage of the cell routing filteris comprised of a look-up table (LTU) and an associated comparator mechanism.The state of each bit of the flag field of an ATM cell preamble will indicatewhether or not the ATM cell is intended for the customer premises equipmentassociated with the bit. A downstream optical network unit contains anassociated set of ATM cell filters associated with customer premisesequipment. Each customer equipment cell filter examines a given bit positionin the flag field portion of each received ATM cell preamble, to see whetherthe flag field bit of the preamble of the received ATM cell is set to aprescribed bit value (e.g. one) - indicating a customer channel request.