An Adaptive Management Approach to Resolving Policy Conflicts

Abstract

The Border Gateway Protocol (BGP) is the current inter-domain routing protocol used to exchange reachability information among Autonomous Systems (ASes) in the Internet. BGP supports policy-based routing which allows each AS to independently define a set of local policies regarding which routes to accept and advertise from/to other networks, as well as which route the AS prefers when more than one route becomes available. However, independently chosen local policies may cause global conflicts, which result in protocol divergence. We propose a new algorithm, called Adaptive Policy Management (APM), to resolve policy conflicts in a distributed manner. Akin to distributed feedback control systems, each AS independently classifies the state of the network as either conflict-free or potentially conflicting by observing its local history only (namely, route flaps). Based on the degree of measured conflicts, each AS dynamically adjusts its own path preferences—increasing its preference for observably stable paths over flapping paths. The convergence analysis of APM derives from the sub-stability property of chosen paths. APM and other competing solutions are simulated in SSFNet for different performance metrics.KeywordsInter-domain RoutingBorder Gateway Protocol (BGP)Feedback ControlConvergence AnalysisSimulation