Design And Implementation Of A Tool For BGP Routing Policy Detection

The Border Gateway Protocol (BGP) allows an autonomous system (AS) to apply diverse local policies for selecting routes and propagating reachability information to other domains without divulging its internal topology and their policies to others.Recent studies have shown that a collection of ASes may have conflicting BGP policies that lead to route divergence. Route divergence can result in route oscillation, which can significantly degrade the end-to-end performance of the Internet. Avoiding these conflicting BGP policies is crucial for the stablility of the Internet routing infrastructure.This paper summarizes the routing configuration based on AS relationship and the category of misconfiguration. Next, a survey of current network policy languages is presented. Then, the RPSL (Routing Policy Specification Language), which is popular used, is taken as the language for specifying the BGP route policy. This paper provides a guide on how to use the language on specifying the ASes relationship.In this paper, a tool is developed to analyse the correctness of the routing configuration in RPSL, and to detect the consistency of the configured policy and actual routing. Based on the comparison between all necessary information in a network model at the BGP level and actual BGP routing, the tool can detect two kinds of misconfiguration, one is origin misconfigurations, the other is the export misconfigurations.At last, using a BGP decision process simulator (C-BGP) to emulate one of the network topology, and detect it using this tool, finally, the results are consistent as expected.