  In this paper we describe a new algorithm for buffered global routing
according to a prescribed buffer site map. Specifically, we describe a provably
good multi-commodity flow based algorithm that finds a global routing
minimizing buffer and wire congestion subject to given constraints on routing
area (wirelength and number of buffers) and sink delays. Our algorithm allows
computing the tradeoff curve between routing area and wire/buffer congestion
under any combination of delay and capacity constraints, and simultaneously
performs buffer/wire sizing, as well as layer and pin assignment. Experimental
results show that near-optimal results are obtained with a practical runtime.
