Some embodiments of the invention provide a method of identifying global
routes for nets in a region of a layout with multiple layers, where each
net has a set of routable elements. The method partitions each layer of
the region into several sub-regions. For each net, the method then
identifies a route that connects the sub-regions that contain the net's
set of routable elements. Some of the identified routes have at least one
non-Manhattan edge and traverse sub-regions on multiple layers.