US Patent 7155697 Routing method and apparatus

A method for routing of some embodiments defines global routes for nets in an arbitrary region of a circuit layout in which each net has a set of pins. The method uses a first set of lines of measure the length of the global routes, a second set of lines to measure congestion of the global routes, and a third set of lines to partition the arbitrary region into a first set of sub-regions. For each net, the method identifies a global route that connects a group of first-set sub-regions that contain the net's set of pins.