Semi-oblivious routing

Mohammad Taghi Hajiaghayi, Robert D. Kleinberg, Tom Leighton

Abstract: We introduce semi-oblivious routing, a generalization of oblivious routing in which multicommodity flows must be routed using a polynomial-sized set of paths which is predefined by the algorithm before the demand matrix for the flow problem is revealed. Our results, which are primarily negative, exclude the possibility of constant-competitive semi-oblivious routing schemes, even when the network is a grid or a seriesparallel graph. We provide an even stronger lower bound on the congestion of constant-bend routing schemes in the grid.