Practical, distributed network coordinates

Abstract

Vivaldi is a distributed algorithm that assigns synthetic coordinates to internet hosts, so that the Euclidean distance between two hosts' coordinates predicts the network latency between them. Each node in Vivaldi computes its coordinates by simulating its position in a network of physical springs. Vivaldi is both distributed and efficient: no fixed infrastructure need be deployed and a new host can compute useful coordinates after collecting latency information from only a few other hosts. Vivaldi can rely on piggy-backing latency information on application traffic instead of generating extra traffic by sending its own probe packets.This paper evaluates Vivaldi through simulations of 750 hosts, with a matrix of inter-host latencies derived from measurements between 750 real Internet hosts. Vivaldi finds synthetic coordinates that predict the measured latencies with a median relative error of 14 percent. The simulations show that a new host joining an existing Vivaldi system requires fewer than 10 probes to achieve this accuracy. Vivaldi is currently used by the Chord distributed hash table to perform proximity routing, replica selection, and retransmission timer estimation.