Project ACORN and distributed approaches to ATM networks

Centralized and distributed approaches to the design and implementation of a multi-gigabit per second asynchronous transfer mode (ATM) switch are discussed. The implementation constraints associated with a centralized switch are demonstrated and an alternative distributed optical network architecture is described. The distributed approach exploits unique opportunities presented through the use of a passive optical medium. A network based on these principles (TeraNet), has been implemented that offers user access rates of 1 Gbit/s. The distributed ATM switch fabric resides in small, geographically dispersed access stations interconnected by a shared, all-optical medium carrying many wavelength-multiplexed channels. Although the underlying multihop architecture for the ATM network produces a lower per-port throughput than that afforded by a large centralized ATM switch, significant implementation advantages exist. Possible techniques to yield a higher per-port throughput approaching that of a large centralized switch are also discussed