Research Of Performance Improvement Methods For NS2

Network simulation is a major method to research computer network. For its low cost, easy operation, convenience and accuracy, network simulation has been widely used in many fields to research the mechanism of networks. With the development of computer network, the networks in the simulation are much larger and more complex. The current methods can hardly satisfy the requirement of the large-scale network simulation. So, how to improve the performance becomes a key problem of network simulation.Currently, most network simulators are based on the discrete-event simulation technique, and NS2 is one of the most famous network simulators. After several simulation experiments on NS2, we analyze the time cost during the simulation, and conclude three factors which can influence the performance of NS2: 1. Processing great number of discrete-events; 2. Constructing the routing table for a large-scale network topology; 3. Tracing during the simulation. And then we present three methods to improve the performance of NS2 based on these three factors. 1. We use simplified link model on some link and ignore the packet details. So it can decrease the number of discrete events and the simulation time; 2. We divide the original node into two kind: router node and terminal node, and only compute the routing table to the router nodes. So it can decrease both scale and time cost of the routing computation; 3. We use a low- priority process to do the I/O operations of the tracing. So it can avoid the interference effect from the I/O operations. Experiments show that compared to the traditional NS2, these three improvement methods can greatly decrease the simulation running time, and meanwhile ensure the accuracy of the results.