Real-time on-line network simulation

Abstract

Abstract: The complexity and dynamics of the Internet is driving the demand for scalable and efficient network simulation. Yet, parallelizing network simulation at packet level does not work efficiently and therefore do not scale to large number of processors because of tight synchronization between network components. To overcome this problem we designed a method in which a large network is decomposed into parts and each part is simulated independently and concurrently with the others. These parts exchange information periodically about the packet delays and drop rates along the paths within each part. Each part iterates over the selected simulated time interval until the exchanged information changes less than the prescribed tolerance. Each decomposed part may represent a subnet or a subdomain of the entire network, thereby mirroring the network structure in the simulation design. The proposed method is independent of the specific simulator technique employed to run simulators of the parts of the decomposed network. Hence, it is a general method for efficient parallelization of network simulation based on convergence to the fixed point solution of inter-part traffic. The method can be used in all applications in which the speed of the simulation is of essence, such as: on-line network simulation, network management, ad-hoc network design, emergency network planning, large network simulation or network protocol verification under extreme conditions (large flows). The paper describes the method, its implementation based on ns simulator, and its performance for sample communication networks.