FluNet: A Hybrid Internet Simulation/Emulation Environment for a Fast Queue Regime∗

Motivated by the scale and complexity of simulating large-scale networks, recent research has focused on hybrid fluid/packet simulators, where fluid models are combined with packet models in order to reduce simulation complexity. However, these simulators still need to track the queuing dynamics of network routers, which generate considerable simulation time-complexity in a large-scale network model. In this paper, we propose a hybrid simulator – FluNet – where queueing dynamics are not tracked. The FluNet simulator is predicated on a fast-queueing regime at bottleneck routers, where the queue length fluctuates on a time-scale that is much faster than the time-scale of end systems. FluNet does not track queue lengths at routers, but instead, uses an equivalent rate based model at the router queue; and queue-based AQM schemes (such as RED) are replaced by equialent rate-based models. This allows us to simulate large-scale systems, where the simulation “time-step-size” is governed only by the time-scale of the end-systems, and not the intermediate routers; whereas a fluid model based simulator that tracks queue-length would require decreasingly smaller step-sizes as the scale size of system increases. We validate our model using a Linux based implementation with real traffic. Our results indicate a good match between packet systems and the associated FluNet system.