DIRSMIN: a fault-tolerant switch for B-ISDN applications using dilated reduced-stage MIN

Abstract

We have developed and analyzed a dilated high-performance fault-tolerant fast packet multistage interconnection network (MIN). This new switch, (d,d')-DIRSMIN, uses dilation to improve performance and fault-tolerance of a network. The links at the input and output stages of the dilated banyan-based MIN are rearranged to create multiple routes for each source-destination pair in the network, after removing the first stage in the network. These multiple paths are link- and node-disjoint. This new MIN can provide low packet-loss probability and high reliability with very little hardware overhead, compared to d-dilated banyan networks (BN). Fault tolerance at low latency is achieved by transmitting multiple copies of each input-packet simultaneously using different routes. A multiple-priority scheme allows alternate paths to be explored simultaneously, which results in higher throughput and reliability under both fault-free and faulty conditions. This guarantees that high throughput is maintained even in the presence of a fault. Throughput is analyzed using analytic and simulation methods; this new design has considerably higher performance in the presence of a permanent faulty switching-element (SE) or link, in comparison to dilated networks. Under non-faulty conditions, both analytic and simulation results show that a (d,d)-DIRSMIN performs better than the original dilated BN with the same SE complexity. We analyze the network reliability and show that the new design has superior reliability compared to competing proposals. In particular, this new design is considerably better than the SEN+, the best known thus far.