Date Added: Jan 2013
Prior analyses of the benefits of routing overlays are based on platforms consisting of nodes located primarily in North America, on the academic Internet, and at the edge of the network. This paper is the first global study of the benefits of overlays on the commercial Internet in terms of round trip latencies and availability, using measurements from diverse ISPs over 1100 locations (77 countries, 630 cities and 6 continents). The authors' study shows that while overlays provide some improvements in North America, their benefits are especially significant for paths with Asian endpoints. Regarding practical considerations in constructing overlay routes, they show that an algorithm that randomly chooses a small number of alternate redundant paths achieves an availability of over 99.5%.