On the power-law of the internet and the hierarchy of BGP convergence
ICA3PP'07 Proceedings of the 7th international conference on Algorithms and architectures for parallel processing
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BGP, the Border Gateway Protocol, is the de facto standard protocol for performing interdomain routing on the Internet today. This thesis combines controlled active measurement in a testbed environment as well as on the actual Internet, correlating routing traffic with the forwarding plane and analyzing the protocol in detail using simulations to expose problems of interdomain routing dynamics. This class of problems may be difficult to reason statically due to the interaction of protocol components and can be observed more easily during run time. They include reachability, forwarding behavior, and convergence dynamics. The first part of this work exposes an unexpected interaction between two protocol features in BGP—route flap damping and path vector-based convergence, significantly delaying convergence. It illustrates the need to carefully analyze BGP's run time behavior and shows the inherent complexity in the BGP dynamics. It provides an excellent example of how new features added to BGP for the purpose of solving an immediate problem can create additional hidden problems due to protocol feature interactions. We designed and implemented an active routing measurement infrastructure— BGP Beacons. It differs from previous efforts in its public and long-term nature and several experimentation features to facilitate measurement interpretation. We demonstrate several uses of this infrastructure to better understand BGP dynamics, one of which being the validation of our conjecture of the interaction of route flap damping and convergence as described in the first part of the dissertation. Contrary to common wisdom, the routing information may not always reflect the underlying packet forwarding behavior or how data packets flow on the Internet. The discrepancies can be caused by various routing anomalies and need to be carefully studied. To understand the impact of routing dynamics on the data plane dynamics, in the last part of the thesis, we describe the development of a tool and associated optimization algorithms to study the interaction between the control plane and the data plane. The main contribution of this dissertation is an experimental framework for improved understanding of the dynamics of interdomain routing. Using this framework, we validated our conjecture that route flap damping can delay convergence. We focus on routing problems such as reachability and forwarding behavior that are difficult to reason statically due to lack of topology and policy information and illustrate through measurement they can be much better understood. As a byproduct of this work, we contribute to the research and operator community an active measurement infrastructure for controlled BGP route injection—BGP Beacons, and a tool to correlate the routing behavior with the packet forwarding behavior—AS-traceroute tool. (Abstract shortened by UMI.)