Parallel network simulation under distributed Genesis

Abstract

We describe two major developments in the general network simulation integration system (Genesis): the support for BGP protocol in large network simulations and distribution of the simulation memory among Genesis component simulations. Genesis uses a high granularity synchronization mechanism between parallel simulations simulating parts of a network. This mechanism uses checkpointed simulation state to iterate over the same time interval until convergence. It also replaces individual packet data for flows crossing the network partitions with statistical characterization of such flows over the synchronization time interval. We had achieved significant performance improvement over the sequential simulation for simulations with TCP and UDP traffic. However, this approach cannot be used directly to simulate dynamic routing protocols that use underlying network for exchanging protocol information, as no packets are exchanged in Genesis between simulated network parts. We have developed a new mechanism to exchange and synchronize BGP routing data among distributed Genesis simulators. The extended Genesis allows simulations of more realistic network scenarios, including routing flows, in addition to TCP or UDP data traffic. Large memory size required by simulation software hinders the simulation of large-scale networks. Based on our new support of distributed BGP simulation, we developed an approach to construct and simulate networks on distributed memory using Genesis simulators in such a way that each participating processor possesses only data related to the part of the network it simulates. This solution supports simulations of large-scale networks on machines with modest memory size.