Multistage bus network (MBN): an interconnection network for cache coherent multiprocessors

Single bus multiprocessor systems do not scale well due to the limited bandwidth of the bus. Hierarchical bus interconnections are scalable, but unfortunately the top level bus becomes a bottleneck for larger systems. The authors present a novel interconnection network called the multistage bus network (MBN). The MBN consists of multiple stages of buses and it preserves the bandwidth properties of a conventional multistage interconnection network (MIN). At the same time the MBN also retains the economic design and fast broadcast advantages of the bus based systems. They show that the MBN performs almost as good as a MIN and is much more cost effective than the MIN. They also design and study a multistage snooping cache protocol for the MBN