Tracking Back the Root Cause of a Path Change in Interdomain Routing

Interdomain routes change over time, and it is impressive to observe up to which extent. Routes may change many times in the same day and sometimes in the same hour or minute. Such changes are caused by several types of events, e.g., a routing policy variation in an ISP, a router reboot, or a link fault. In this paper we do a step towards the identification of the cause of route changes, a problem that is attracting increasing attention from both researchers and network administrators. Namely, we propose a methodology for analyzing a given BGP route change in order to, at least partially, locate the event that triggered the change. The methodology is supported by a publicly available on-line service.