While a communication network is a critical component for an efficient system-on-chip multiprocessor, there are few approaches available to help with system-level architectural exploration of such a specialized interconnection network. This paper presents an integrated modeling, simulation and implementation tool. A high level description of a network-on-chip can be simulated and converted into VHDL. The system simulation supports multiple instruction-set simulators, and obtains cycle-accurate performance metrics. This way, an optimal network configuration can be determined easily. We discuss our approach by designing a flexible network-on-chip and present implementation results after mapping into FPGA. The performance of our automatically generated network is comparable with a reference design directly developed in HDL.