This is an implemention of Congestion-Aware Routing (CAR) in Tor. Wang et al [1]. proposed opportunistic and active probing techniques to measure RTTs, which allows them to compute congestion times, and they use these measurements to mitigate congestion using both an instant response for temporary congestion and a long-term response for low-bandwidth conditions. In our simulation, we follow the method of Wacek et al. [2], who also simulated CAR and ignored the long-term response due to its small impact on performance. According to the paper, the CAR discards the circuits that are congested and reattaches the streams to other circuits. We did not implement this because it causes new connections to the servers and everything will be started from scratch and will harm the users' experience.
This is an implemention of Congestion-Aware Routing (CAR) in Tor. Wang et al [1]. proposed opportunistic and active probing techniques to measure RTTs, which allows them to compute congestion times, and they use these measurements to mitigate congestion using both an instant response for temporary congestion and a long-term response for low-bandwidth conditions. In our simulation, we follow the method of Wacek et al. [2], who also simulated CAR and ignored the long-term response due to its small impact on performance. According to the paper, the CAR discards the circuits that are congested and reattaches the streams to other circuits (Switching to Another Circuit part in Instant Response method). We did not implement this because it causes new connections to the servers and everything will be started from scratch and will harm the users' experience.
# Implementations
-**CAR-tor-0.2.5.2-alpha** is the implementation on the Tor 0.2.5.2-alpha