WICI: an efficient hybrid routing scheme for scalable and hierarchical networks

Many recent supercomputers employ either a cluster-based design or a highly scalable network. Clustering is built-in in a hierarchical system, while highly scalable networks like mesh or torus could be easily partitioned into modules to form several clusters. This paper first specifies a self-routing connection method in a recently introduced class of hierarchical topology called de Bruijn-Cube (dBCube) network, and presents a deadlock-free routing scheme using virtual channels. A new switching method called Wormhole Intracluster Cut-through Intercluster (WICI) routing is also introduced to improve the network performance fairly close to the virtual cut-through and to maintain the buffer cost as compared to prevalent routing schemes of wormhole. Usefulness of WICI routing has been demonstrated for the hierarchical network of dBCube and large networks like mesh and torus, and simulation results for WICI routing are compared with wormhole and virtual cut-through routings.