New techniques employing high fidelity, real-time network emulations are changing the way that network-centric systems are tested and evaluated. Emulation plays an important role in evaluating network constructs after early stage, abstracted simulations and before late stage full prototype testbeds. From the component level to the system-of-systems level, emulation enables network designers to test and evaluate the system, greatly reducing the cost and effort required to thoroughly test and validate throughout the design cycle. Not all network simulators are capable of true emulation. To be a true replacement for a network, an emulation must support real time speed, full packet fidelity, and transparency.