A method to reduce the problem complexity maintains a relatively high quality port assignment by abstracting local connections in the macro when performing the port assignment. This is done for netlength, congestion as well as timing. The internal netlist of the macro is abstracted in such a way that the optimization of the external interconnect can be done in an efficient manner. Three levels of abstractions are described. A first level optimizes the top level interconnect, a second level optimizes the top level and macro interconnects, while a third level optimizes the top level timing.