Affiliations: AT&T Bell Laboratories, Holmdel, New Jersey, USA | AT&T Bell Laboratories, Naperville, Illinois, USA | AT&T Bell Laboratories, Andover, Massachusetts, USA | NTT Transmission Systems Laboratories, Yokosuka, Japan
Abstract: A prototype 2.5 Gb/s ATM switch fabric has been developed for flexible broadband applications. The prototype configuration supports multiple standard line card interfaces, e.g., STM-1 (155 Mb/s), STM-4c (622 Mb/s) and STM-16c (2.5 Gb/s). The ATM cells are extracted from the payload of these SDH signals and are multiplexed inside the fabric to an internal equivalent cell rate of 2.5 Gb/s. Routing is done subsequently on a cell-by-cell basis according to the cell header address information (VPI and/or VCl). The core fabric of the switch is therefore a 2.5 Gb/s ATM switch. The fabric is designed using the theory of the Growable Switch Architecture guaranteeing the best possible delay-throughput performance for arbitrary traffic distributions for independent inputs. In this prototype implementation, careful considerations have been given to optimize various aspects such as physical size, physical growth, power consumption, protection switching, maintenance and reliability. The core 2.5 Gb/s fabric prototype can grow from 8 x 8 (supporting up to 128 STM-1 interfaces) to larger sizes (e.g., 64 x 64, supporting up to 1024 STM-1 interfaces). Considerations for substantially larger switch sizes have also been taken into account in the design. Descriptions of our initial prototype and its evolution to larger switch dimensions are discussed.
