More or Less Tightly Coupled Networks

A wide variety of different architectures have been proposed for large networks of computers. These include systems using buses, cross-point switches, rings, lattices, stars, snowflakes and similar clusters, clusters of clusters, binary trees, n -ary trees, pyramids, and binary n -cubes—among many other interconnection patterns. This chapter describes most of these architectures and explores the striking similarities between many of these on-the-surface-different configurations. It discusses the networks that, with very few exceptions, contain only a few dozen computers. But networks are being explored with an eye to the relatively near future when very-large-scale integration technology will open up the possibility of far larger numbers, in the hundreds, thousands, or millions. Most of these systems exist only as paper designs and are still being thought through. In contrast to the arrays only a handful of small multiple instruction, multiple data networks have been built or even designed in full detail.