two open source network emulators are common open research emulator (core) and extendable mobile ad-hoc network emulator (emane). they both support operation as network black boxes, i.e. external machines/devices can be hooked up to the emulated network with no knowledge of emulation. they also both support both wired and wireless network emulation with various degrees of fidelity. core is more useful for quick network layouts (layer 3 and above) and single machine emulation. emane is better suited for distributed high fidelity large scale network emulation (layers 1/2).