All-Digital Techniques for the Optical Broadband ISDN

Advances in technology have brought down the cost of deployment for fibre-based communications systems. The extension of fibre-based systems directly into businesses and residences will have a major impact on the development of the integrated service digital network (ISDN), ushering in what is commonly referred to as broadband ISDN (BISDN). BISDN can support a wide variety of services over high-bandwidth digital interfaces ranging from very low bit-rate telementry through full-motion high-definition video. Bellcore has been investigating two types of switching techniques for use in the BISDN: space division circuit switching and high-speed packet switching. Interest in the design of high-speed packet switches is now receiving greater emphasis because of the selection of asynchronous transfer mode (ATM) as the predominant switching and multiplexing technique for BISDN. Both types of switching fabrics can be dimensioned to operate efficiently over the proposed SONET transmission system. This paper focuses on the ATM hardware for a second generation prototype of a local access BISDN that is being constructed to more fully understand the implications and trade-offs involved in the design of BISDN systems.