LOREN: A Scalable Routing Method for Layout-Conscious Random Topologies

End-to-end network latency has become an important issue for parallel application on large-scale high performance computing (HPC) systems. It has been reported that randomly-connected inter-switch networks can lower the end-to-end network latency. The trade-off is a large amount of routing information. For irregular networks, minimal routing is achieved by using routing tables for all destinations in the network. In this work, a novel distributed routing method called LOREN (Layout-Oriented Routing with Entries for Neighbors) to achieve low-latency with a small routing table is proposed for irregular networks whose link length is limited. The routing tables contain both physically and topologically nearby neighbor nodes to ensure livelock-freedom and a small number of hops between nodes. Experimental results show that LOREN reduces the average latencies by 2.8% and improves the network throughput by up to 39% compared with a conventional compact routing method. Moreover, the required routing table size is reduced by up to 67%, which improves scalability and flexibility for implementation.