Optimizing end-to-end throughput for data transfers on an overlay-TCP path

Abstract

We consider an overlay network where traffic on an overlay hop is carried in one or more TCP connections established between the overlay nodes at the ends of the hop. We are interested in maximizing the throughput of data carried by this type of overlay network. To that end, we focus on a single path in such a network and investigate how one can determine the number of TCP connections on each overlay hop so as to maximize the throughput of the data carried end-to-end on that path. We first show that having more than one TCP connection on some overlay hops can indeed increase the throughput on overlay paths. We then propose the Adaptive Overlay-TCP Provisioning approach, that, based on the path state, dynamically introduces and removes TCP connections on individual overlay hops to maximize throughput while minimizing the overhead of extraneous connections. We consider two schemes to assess the path state, the intermediate buffer occupancy scheme and the isolated rate probing scheme, and evaluate them experimentally on a set of Planetlab nodes. We show that these schemes can significantly improve the end-to-end throughput with very little overhead. © IFIP International Federation for Information Processing 2005.