Negotiated congestion
Beginner
Letting wires compete for crowded spots, with each spot getting more expensive every time it is fought over, until every wire finds a place.
Novice
A form of rip-up and reroute in which a resource’s price rises with how many nets share it now and with how often it has been overused before. Nets with alternatives move away; the net with no other option keeps the resource.
Expert
From PathFinder (1995): node cost , with base cost , a history term that only grows, and a present-sharing penalty . Every net is rerouted each iteration, and timing-critical nets can weight delay over congestion. The idea underlies most academic and open global routers.