A BGP Solver for Hot-Potato Routing Sensitivity Analysis

Bruno Quoitin and Sébastien Tandel

The interactions between the IGP and BGP routing protocols which are running inside an ISP's network are sometimes hard to understand. The problem becomes particularly complex when there are dozens of routers/links and several thousands of destination prefixes. In this paper, we present a publicly available routing solver to evaluate routing what-if scenarios. The solver is able to model the complete network of an ISP and given the external routes learned by this ISP, to compute the paths towards all the destination prefixes. We demonstrate the use of our routing solver, C-BGP, by showing the results of an analysis of the link/router failure sensitivity in a transit network. Based on the analysis' results, we can pinpoint links/routers whose failure has an important impact on the selection of BGP routes. The deployment of protection techniques that are used for optical links, SONET-SDH and MPLS should be considered for these links/routers.
Published in EUNICE 2005.

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