In the past, network performance has been strongly determined by the capacity of the wired or wireless links. In future, however, we can expect that with the emergence of resource-constrained nodes (e.g. software routers) and highspeed links (e.g. optical fiber), the network nodes themselves will be the bottleneck. To increase the packet processing of resource-constrained nodes, parallel processing with multi-core processors is required. Intra-node resource contention can have a strong negative impact on the corresponding network node and, therefore, also on the overall performance of the network. However, several commonly used network simulators only offer a rather simplistic node model and do not take into account intra-node resource contention. In particular, latencies and input queueing behavior of resource-constrained nodes are typically not modeled in current simulators. We propose a unified and extensible approach to model intra-node resource contention which enables us to identify and predict performance bottlenecks in current and future networks. We implemented our model as an extension to the network simulator ns-3. The simulation results show that our approach significantly outperforms the original ns-3 in terms of realistic modeling. This claim has been validated successfully by means of real testbed measurements.
