Scalable network architectures using the optical transpose interconnection system (OTIS)

The optical transpose interconnection system (OTIS) proposed makes use of free-space optical interconnects to augment an electronic system with non-local interconnections. In this paper we show how these connections can be used to implement a large-scale system with a given network topology using small copies of a similar topology. In particular we show that, using OTIS, an N/sup 2/ node 4-D mesh can be constructed from N copies of the N-node 2-D mesh, an N/sup 2/ node hypercube can be constructed from N copies of the N-node hypercube, and an (N/sup 2/, /spl alpha//sup 2/, c/2) expander can be constructed from N copies of an (N, /spl alpha/, c) expanders, all with small slowdown. We also show how this expander construction can be used to build multibutterfly networks in a scalable fashion. Finally, we demonstrate how the OTIS connections can be used to produce a bit-parallel crossbar using many copies of bit-serial crossbars with minimal overhead.