Both Emulation and Simulation are valid tools to perform network research. Mininet is a network emulator designed to run real network software. It emerged as a

Both Emulation and Simulation are valid tools to perform network research. Mininet is a network emulator designed to run real network software. It emerged as a leading tool to evaluate software defined networking solutions. Mininet leverages openvswitch which is the same software that would run on the networking boxes. So the TCP/IP stacks are emulated. This means that the system has very high fidelity making it behave close to the real system. Mininet runs in 'wall-clock' time. (or real-time) On the other hand, simulation has a more difficult time achieving the same fidelity due to the difference in the execution modes. Discrete event simulation works by maintaining a queue of events. Each event has a timestamp that advances the simulation clock forward. Each event can create 0 or more events. The behavior of the network (adding delays / dropped packets / etc.) are simulated with models. This simulation allows a process to run real application code by invoking it from an event handler. A discrete event simulation uses virtual clocks which can be faster or slower than wall-clock time. As a general rule we can say that simulation is more scalable than emulation (10s vs 1000000s of nodes) while emulation has higher fidelity (more accurately captures behavior of real system).