Looking ahead of real time in hybrid component networks

Abstract

While network simulation is a widely used technique for developing, testing and evaluating network protocols and applications, it is difficult and time-consuming to develop detailed models of the entire protocol stack and the application that is being evaluated. Hybrid component networks combine simulation models of protocols and applications with physical implementations of other protocols and/or applications, which can alleviate modeling complexity and build accurate models. However, hybrid component networks require that the simulated components execute faster than real time. Parallel simulation techniques can greatly improve the performance of hybrid component networks and facilitate evaluation of larger networks than would feasible only with sequential execution. In parallel simulation, one of the most important properties to be exploited from the simulation is “lookahead,” but none of the previous studies has exploited the lookahead from the physical implementation of protocols or applications. We have developed Virtual Socket Interface (VSI), which exploits real time lookahead from the interactions between operational applications and simulated networks in GloMoSim [1], a parallel discrete event network simulator. This paper presents the implementation of VSI with the notion of real time lookahead and evaluates VSI for typical wireless ad hoc network scenarios. The results of the study demonstrate that the parallel simulation with the real time lookahead greatly enhances the capability of hybrid component networks.