NEMO: A Flexible Java-based Network Emulator

Network emulation provides the capability to evaluate applications on standalone systems, representing a trade-off between real infrastructures and simulators, providing a lowlayer virtual network, and yet allowing real high-layer application code to be executed. Moreover, network emulation is useful to study and evaluate the behavior of applications in different conditions (maybe sometimes difficult to reach in real networks), in turn allowing a rapid deployment of hybrid real hardware/virtual network topologies. In this paper, a modular, flexible and highly scalable Java-based network emulator, denoted as NEMO, is proposed. NEMO can be integrated with external open-source Java applications or used as a virtualization mechanism, able to run third-party Java binary applications on a virtual node attached to either a virtual network or a real external network, in a completely transparent way for the end-user. Moreover, NEMO allows to plug in user-defined network components and run virtual networks composed by millions of nodes on a single end-user machine, as well as on a distributed infrastructure.