Using Ghosts for Global Topology Knowledge in Space-Parallel Distributed Network Simulations

Abstract

The authors discuss an approach to federated network simulations that eases the burdens on the simulation developer in creating space-parallel simulations. Previous approaches have had difficulties that arise from the need for global topology knowledge when forwarding simulated packets between federates. In all but the simplest cases, proper packet-forwarding decisions between federates requires routing tables of size O(mn), where m is the number of nodes modeled in a particular federate, and n is the total number of network nodes in the entire topology. Furthermore, the benefits of the well-known NIx-Vector routing approach cannot be fully achieved without global knowledge of the overall topology. The authors overcome these difficulties by using a topology partitioning methodology that uses ghost nodes. They show experimentally that the memory overhead associated with ghosts is minimal relative to the overall memory footprint of the simulation.