Latency-Based Anycast Geolocation: Algorithms, Software, and Data Sets

Abstract

Use of IP-layer anycast has increased in the last few years beyond the DNS realm. Existing measurement techniques to identify and enumerate anycast replicas exploit specifics of the DNS protocol, which limits their applicability to this particular service. In this paper, we propose and thoroughly validate a protocol-agnostic technique for anycast replicas discovery and geolocation. Furthermore, we also provide the community with open-source software and data sets allowing others to replicate our experimental results, potentially facilitating the development of new techniques such as ours. In particular, our proposed method achieves thorough enumeration and city-level geolocalization of anycast instances from a set of known vantage points. The algorithm features an iterative workflow, pipelining enumeration (an optimization problem using latency as an input), and geolocalization (a classification problem using side channel information, such as city population) of anycast replicas. Results of a thorough validation campaign show our algorithm to be robust to measurement noise, and very lightweight as it requires only a handful of latency measurements.