Cost-Efficient SCI-based Banyan Networks

Today, various high speed transmission technologies and protocols such as Fiber Channel, FDDI, ATM and Fast Ethernet are wide spread, complemented by systemor local area communication networks such as HIPPI, OMI-HIC [IEEEP], Myrinet [Boden95], RACEway [Mercury95], Memory Channel [Gillet96] and SCI (Scalable Coherent Interface) [IEEE92]. This paper discusses the efficient use of 4-port SCI switches, resulting in 5-fold performance compared to SCI switches in the standard operating mode. Furthermore, Banyan-like topologies are proposed based on such efficient switches. The novel networks are suited for applications in parallel computers, clusters of workstations [Ander95] and local area multiprocessors [Gustav94]. Their performance improvements are the higher the larger the switch size is, while exhibiting lower costs at the same time. The prerequisite is that data locality in the traffic patterns is present. In chapter 2, a short review on the SCI technology and the internal set-up of SCI switches is given. In chapter 3, the efficient use of SCI switches in uniform and non-uniform memory-access architectures (UMA/NUMA) is presented. In the fourth chapter, the achieved improvements are applied for multistage Banyans, that are constructed by an intra-switch wiring on higher number basis than 2, resulting in enhanced topologies. In the sixth chapter, performance figures for the 4-port switch and the multistage topologies are given for both, biand unidirectionally-connected operating modes. The results show better behaviour for bandwidth, latency and packet losses compared to standard SCI-based Banyans. Figures were obtained by means of a self-written simulation program called SCINET.