Pythia

Abstract

An accurate and exhaustive knowledge of the Internet topology is essential for a deep understanding of such a complex and ever-evolving ecosystem. In this context, a wellknown key challenge is represented by alias resolution, i.e. the process of grouping under a unique identifier the addresses owned by the same network layer device. While several techniques exist, each solution shows specific limitations such that the alias resolution problem appears far from being definitively solved. In this work, inspired by a previous technique and the lessons learned by experimenting with IP options, we present, evaluate and release Pythia, a novel active probing-based alias resolution technique. Pythia exploits a combination of (i) UDP packet probes and (ii) the IP Prespecified Timestamp option and it is purposely designed to reconstruct a specific category of routers. By using the reliable topological information provided by IGMP probing as a reference, we experimentally evaluate Pythia and compare it to previously proposed techniques according to multiple performance metrics. Experimental results show how Pythia reaches higher performance in terms of applicability and trustworthiness.