Optical Passive Star Topology

This paper examines optical star coupled systems as a means of providing interprocessor communication. In particular, a MIMD (multiple instruction, multiple data) distributed memory parallel computer system environment is considered. Media access control protocols that maintain good performance with high capacity optical channels are investigated. Three examples of star-coupled structures are introduced, one that exhibits optical self-routing. Self-routing single-step optically interconnected communication structures can be designed through the incorporation of agile laser diode sources and wavelength tunable optical lters in a wavelength division multiple access environment. Intermediary latencies typical of MIMD distributed memory systems are eliminated. The degree and diameter of the resulting structures are dramatically reduced, and the complexity of the communication subsystem is reduced since intermediate bu ering and routing of packets are eliminated. Four multiple access protocols are considered. This paper introduces two non-control channel based protocols. The resulting performance, in terms of total system and maximum system throughput, are compared with two previously introduced control-channel based protocols. This paper demonstrates that the two non-control channel based protocols are implementationally simpler, have superior performance, and are targeted to architectures with lower system complexity than the previously introduced control channel based protocols.