Siamese-twin: a dynamically fault-tolerant fat-tree

Fat-trees are a special case of multistage interconnection networks with quite good static fault tolerance capabilities. They are however straightforwardly unable to provide local dynamic fault tolerance. In this paper we propose a network topology based on the fat-tree using two parallel networks with crossover links between them in an effort to enable dynamic fault tolerance. We evaluate and compare this topology with two other similar fat-tree topologies and show through simulations that the new topology is able to improve slightly upon the ability to tolerate faults statically. More importantly, we show that the new network topology is the only one of the evaluated topologies able to tolerate one fault dynamically, with a superior network performance in the face of dynamically handled faults.