Simulating a NoC at the RTL level can be extremely complex, the simulation of a relatively small NoC, such as a 4×4 mesh, can involve observing thousands of wires on a standard HDL simulator. The facilities of JHDL to extend the simulator environment together with the possibility to fully analyze the runtime object model of the circuit offers a great opportunity to develop modules that address complex features like high level validation and performance evaluation. We present a developed tool that allows defining a NoC architecture models with some flexibility. Traffic generation processes described with high level language can be added to the model. Simulation can be used to validate the system operation on realistic conditions and get accurate values of expected performance.