This papers presents the design of a Network-on Chip (NoC) simulator for design space exploration of router ar chitectures. The simulator supports cycle-accurate router models and in addition allows the simulation of router architectures, which can adjust their processing according to the traffic type. Realistic traffic patterns are derived from task graph models of real-world applications that are simulated in parallel to the NoC at transaction level. Combining cycle-accurate router simulation and abstract task graph simulation circumvents the limitations of most NoC simulators, which either use synthetic traffic patterns or unrealistic and fixed router models. The proposed simulator architecture is presented in detail and its suitability is shown by means of a case study.