TCP performance with deflection routing in the Internet

Deflection routing has been well studied for optical networks with regular topologies. In this paper, we propose using deflection routing in the Internet and study its TCP performance. In particular, we show that when the difference between the delay of the deflection path and the shortest path (i.e., the deflection cost) is in a certain range, deflection routing can make almost full use of the free bandwidth in the deflection path and hence achieve substantial throughput improvement. In the worst case when the deflection cost is large, deflection routing can achieve an aggregate throughput no less than that without deflection routing. We analyze the underlying mechanisms of these characteristics. In order to extend the usefulness of deflection routing, we also propose a deflection routing scheme with adaptive deflection point and show via simulation that this scheme can achieve very high throughput as long as the deflection cost is no larger than a certain value. We show that deflection routing is friendly to the existing traffic in the deflection path. One possibly unfavorable requirement of deflection routing is that it should be enabled for either all or none of the flows contending for the same outgoing (congested) link.