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
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
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