The Internet being very large and rapidly evolving, it is always difficult to maintain a real-time view of its topology without continuously flooding it with a large number of concur- rent probe packets. Although there have been considerable re- search efforts to reduce the number of these probes (e.g. reducing redundancies), the congestion and network overhead they cause have often been overlooked. In this paper, we propose SPIRA, a network-friendly protocol to discover the Internet topology. Our protocol regulates the throughput of probes as a function of the observed delay and loss measurements. Starting from a monitoring computer and a set of destinations, a cartography of intermediate routers (IP addresses and coordinates) and links between them (interfaces and delays) is deduced in a short time and with a minimal overhead. We evaluate the performance of our protocol using real experiments on the PlanetLab testbed.
