Evaluation of dynamic circuit switching to reduce congestion in Tor

The Tor network is a widespread overlay anonymous network that is used by millions of users today. Tor focuses on improving the privacy of its users by routing their traffics through a series of onion routers that are located around the world. Since Tor operations mainly depend on volunteers who donated onion routers in the network, there are variances of capacities amongst different onion routers, which degrade the performances of Tor. In an effort to reduce the congestion problems in Tor, first we implemented control metrics to detect congestion on the entry OR. Second, we performed dynamic estimation of circuit congestion to select the best path in Tor. Third, we addressed the unfair distribution of bandwidth between the bulk and light traffics in Tor. We distributed the light and bulk traffics in Tor by having almost the same throughputs compared to default Tor multiplexing circuit approach. We use RTTs, circuit congestion and OR capacities as the main metrics to select the path. From our experimental analysis, we showed that our circuit switching method is effective to reduce the congestion problems in Tor.