Analyzing BGP ASPATH Behavior in the Internet

In this paper we introduce a new metric for analyzing the behavior of ASPATH values in the Border Gateway Protocol (BGP) routing protocol. We base our metric on the edit distance algorithm, an algorithm used for approximate string matching. We modify this basic algorithm by adding features that embed BGP domain knowledge. This allows us to perform meaningful comparisons of ASPATH values contained in BGP update messages. We call our modified metric ASPATH Edit Distance(AED). We illustrate the application of this metric to characterize ASPATH changes at a global scale using the example of a major Internet routing anomaly. At the other end of the spectrum we illustrate how this metric can be used to quantify and model the behavior of ASPATH values for individual Autonomous Systems. AED provides us with an important measure with which we can study the behavior of ASPATHS in the Internet. With sufficient refinement, AED can be suitably adapted and used alongside other metrics in BGP routing anomaly detection algorithms and tools.