Re:Shadow Simulator – run real applications over a simulated...
by nomadiccoder on Tuesday April 20, 2021 @09:04AM
(#26874024)
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).
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).