On the Feasibility of Bandwidth Detouring

Internet applications that route data over default Internet paths can often increase performance by sending their traffic over alternative “detour” paths. Previous work has shown that applications can use detour routing to improve end-to-end metrics such as latency and path availability. However, the potential of detour routing has yet to be applied where it may be most important: improving TCP throughput. In this paper, we study the feasibility of bandwidth detouring on the Internet. We find that bandwidth detours are prevalent: between 152 Planetlab nodes, 74.8% of the paths can benefit from detours with at least 1 Mbps and 20% improvement. To understand how to exploit bandwidth detours in practice, we explore the trade-offs between networkand transport-level mechanisms for detouring. We show, both analytically and experimentally, that direct, TCP-based detour routing improves TCP throughput more than encapsulated, IP-based tunneling, although the latter provides a more natural interface.