How and how much traceroute confuses our understanding of network paths

Traceroute is largely considered as the number-one tool when troubleshooting the network, with innumerable applications, such as pinpointing the routing deficiencies or detecting and locating network outages. Previous works have extensively investigated pitfalls and flaws causing the measurements performed with this tool to be inaccurate or incomplete. In this paper, we show how, even in the absence of all these well-investigated pitfalls and flaws, our ability to properly troubleshoot the network with Traceroute is strongly limited. Indeed, by using state-of-the-art alias resolution techniques, we investigate how and how much the IP-level description provided by Traceroute can distort our understanding of the characteristics of Internet paths. We experimentally evaluate the impact on path properties like equal-cost multipaths, loops, routing cycles, load balancing, route prevalence and persistence. Our results confirm that researchers and network operators relying on Traceroute may poorly estimate (i) the number of multiple equal-cost routes to the destination; (ii) the presence of suboptimal routing in the network; (iii) the routing stability.