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Network coordinates provide a mechanism for selecting and placing servers
efficiently in a large distributed system. This approach works well as
long as the coordinates continue to accurately reflect network topology.
We conducted a long-term study of a subset of a million-plus node
coordinate system and found that it exhibited some of the problems for
which network coordinates are frequently criticized, for example,
inaccuracy and fragility in the presence of violations of the triangle
inequality. Fortunately, we show that several simple techniques remedy
many of these problems. Using the Azureus BitTorrent network as our
testbed, we show that live, large-scale network coordinate systems behave
differently than their tame PlanetLab and simulation-based counterparts.
We find higher relative errors, more triangle inequality violations, and
higher churn. We present and evaluate a number of techniques that, when
applied to Azureus, efficiently produce accurate and stable network
coordinates
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