Interdomain path changes occur frequently. Because routing protocols expose insufficient information to reason about all changes, the general problem of identifying the root cause remains unsolved. In this work, we design and evaluate PoiRoot, a real-time system that allows a provider to accurately isolate the root cause (the network responsible) of path changes affecting its prefixes. First, we develop a new model describing path changes and use it to provably identify the set of all potentially responsible networks. Next, we develop a recursive algorithm that accurately isolates the root cause of any path change. We observe that the algorithm requires monitoring paths that are generally not visible using standard measurement tools. To address this limitation, we combine existing measurement tools in new ways to acquire path information required for isolating the root cause of a path change. We evaluate PoiRoot on path changes obtained through controlled Internet experiments, simulations, and ‘in the wild ’ measurements. We demonstrate that Poi-Root is highly accurate, works well even with partial information, and generally narrows down the root cause to a single network or two neighboring ones. On controlled experiments PoiRoot is 100% accurate, as opposed to prior work which is accurate only 61.7 % of the time.

We consider the intra-AS route dissemination problem from first principles, and illustrate that when known route dissemination techniques propagate even a single external routing change, they can cause transient anomalies. These anomalies are not fundamental; they are artifacts of the order in which existing proposals disseminate routes. We show that carefully ordering route updates avoids transient looping and black holes. Perhaps surprisingly, this ordering may be enforced in a completely distributed fashion, while retaining familiar correctness, scalability, and convergence properties.

Internet routing suffers from persistent and transient failures, circuitous routes, oscillations, and prefix hijacks. A ma-jor impediment to progress is the lack of ways to conduct impactful interdomain research. Most research is based ei-ther on passive observation of existing routes, keeping re-searchers from assessing how the Internet will respond to route or policy changes; or simulations, which are restricted by limitations in our understanding of topology and policy. We propose a new class of interdomain research: re-searchers can instantiate an AS of their choice, including its intradomain topology and interdomain interconnectivity, and connect it with the “live ” Internet to exchange routes and traffic with real interdomain neighbors. Instead of be-ing observers of the Internet ecosystem, researchers become members. Towards this end, we present the PEERING testbed. In its nascent stage, the testbed has proven extremely useful, resulting in a series of studies that were nearly impossible for researchers to conduct in the past. In this paper, we present a vision of what the testbed can provide. We sketch how to extend the testbed to enable future innovation, taking advan-tage of the rise of IXPs to expand our testbed.