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Dario Rossi, Telecom ParisTech

"Anycast enumeration and geolocation"


Use of anycast IP addresses has increased in the last few years: once relegated to DNS root and top-level domain servers, anycast is now commonly used to assist distribution of general purpose content by CDN providers. Yet, most anycast discovery methodologies rely so far on DNS, which limits their usefulness to this particular service.

This raises the need for protocol agnostic methodologies, that should additionally be as lightweight as possible in order to scale up anycast service discovery. In this keynote we discuss challenges in devising methods that allow for exhaustive and accurate enumeration and city-level geolocation of anycast replicas, with the constraints of only leverages a handful of latency measurements from a set of known probes.

We describe one such method that exploits an iterative workflow to enumerate (optimization problem) and geolocate (classification problem) anycast instances. Results of a thorough validation campaign based on available ground truth (several DNS root servers), using multiple measurement infrastructures (PlanetLab, RIPE), are presented, showing extremely accurate results even with simple algorithms (that we compare with the global optimum).