Limitations of network emulation with single-machine and distributed ns-3

Research on large-scale internet services requires an extensive evaluation prior to deployment. A good analysis must include tests over large networks, using real devices and a considerable number of users. However, how to test in these scenarios with many users is an open question. Network emulation can be a good alternative before real deployments, which are complex and expensive. In this paper, we examine the new ns-3 network simulator/emulator in order to determine its capacity in the evaluation of large scale services. For that purpose, a real client/server video service is deployed over an emulated network. The service is progressively scaled up by increasing the number of clients on a single machine. In addition, we have extended ns-3 to support a distributed architecture for network nodes, thus, we repeat the experiments with a distributed set-up. Advantages, disadvantages, possibilities and limitations of both approaches are thoroughly discussed.