Towards Realizing the Performance and Availability Benefits of a Global Overlay Network

Abstract

Prior analyses of the benefits of routing overlays are based onplatforms consisting of nodes located primarily in North America, onthe academic Internet, and at the edge of the network. This paper isthe first global study of the benefits of overlays on the commercialInternet in terms of round trip latencies and availability, usingmeasurements from diverse ISPs over 1100 locations (77 countries, 630cities and 6 continents).Our study shows that while overlays provide some improvements in North America, their benefits are especially significant for paths withAsian endpoints. Regarding practical considerations in constructingoverlay routes, we show that an algorithm that randomly chooses asmall number of alternate redundant paths achieves an availability ofover 99.5%. We also propose and evaluate a simple predictive schemethat achieves almost optimal latency using only 2-3 paths, and thatthis is achievable with surprisingly persistent routing choices.