A simulator may not be able to launch a sophisticated attack, but most exploited vulnerabilities result from incorrectly checked arguments and race conditions. Most current simulators require protocols to be re-implemented inside the simulator. This is a tedious and error-prone process. A few simulators implement emulation, where the simulator interfaces with real hosts running a live system, thus requiring minimal additional work by the developer. However, these simulators do not integrate the other features described here.
Most current simulators have a few fixed degrees of fidelity.
Instead, a continuous fidelity simulator would allow the developer to smoothly trade-off simulation time and accuracy in each simulation run and also in different parts of the simulated network in the same run. Most current simulators have no facilities for automated cross-validation with in situ measurement. By integrating a simulator with a network monitoring system, the simulator could automatically validate that its results approximate those measured in the Internet. Bibliography JP00 David B. Johnson and Charles Perkins. Internet Engineering Task Force, nov 2000.