Topology Discovery at the Router Level: A New Hybrid Tool Targeting ISP Networks

For a long time, traceroute measurements combined with alias resolution methods have been the sole way to collect Internet router level maps. Recently, a new approach has been introduced with the use of a multicast management tool, mrinfo, and a recursive probing scheme. In this paper, after analyzing advantages and drawbacks of probing approaches based on traceroute and mrinfo, we propose a hybrid discovery tool, Merlin (MEasure the Router Level of the INternet), mixing mrinfo and traceroute probes. Using a central server controlling a set of distributed vantage points in order to increase the exploration coverage while limiting the probing redundancy, the purpose of Merlin is to provide an accurate router level map inside a targeted Autonomous System (AS). Merlin also takes advantage of alias resolution methods to reconnect scattered multicast components. To evaluate the performance of Merlin, we report experimental results describing its efficiency in topology exploration and reconstruction of several ASes.