Network sensitivity to hot-potato disruptions

International audienceHot-potato routing is a mechanism employed when there are multi-ple (equally good) interdomain routes available for a given destina-tion. In this scenario, the Border Gateway Protocol (BGP) selects the interdomain route associated with the closest egress point based upon intradomain path costs. Consequently, intradomain routing changes can impact interdomain routing and cause abrupt swings of external routes, which we call hot-potato disruptions. Recent work has shown that hot-potato disruptions can have a substantial impact on large ISP backbones and thereby jeopardize the network robust-ness. As a result, there is a need for guidelines and tools to assist in the design of networks that minimize hot-potato disruptions. How-ever, developing these tools is challenging due to the complex and subtle nature of the interactions between exterior and interior rout-ing. In this paper, we address these challenges using an analytic model of hot-potato routing that incorporates metrics to evaluate network sensitivity to hot-potato disruptions. We then present a methodology for computing these metrics using measurements of real ISP networks. We demonstrate the utility of our model by an-alyzing the sensitivity of a large AS in a tier 1 ISP network