The TopHat project, initiated by UPMC during the  OneLab  project, aims at developing platforms and tools to actively probe the Internet topology, and serve live and historic measurements to the community. Data is made available through this interface as well as an XMLRPC API.

TopHat relies on  TDMI (TopHat Dedicated Measurement Infrastructure) , which is currently deployed on more than 400 nodes on the PlanetLab testbed, and periodically makes snapshots of the overlay topology. It complements its own measurements with data originating from several  interconnected platforms .