Distance Metrics in the Internet

We consider and compare four Internet distance metrics and analyze the predictive power of these metrics in selecting, from a given source, the lowest latency destination from among a candidate set. The four metrics are: IP path length; autonomous system (AS) path length; great circle geographic distance; and previously measured round trip time (RTT). We describe general properties of these four metrics and, using an unprecedented volume of real Internet macroscopic topology and RTT data, compare their correlation with actual RTT to the destination. The new methodology we propose for testing different metrics is suitable for evaluating new distance estimation techniques as they become available.