Link-Rank: a graphical tool for capturing BGP routing dynamics

Failures at the BGP level can have significant impact on the overall Internet. Understanding the behavior of BGP is thus both an important practical challenge and an interesting research problem. To understand the true dynamics, and help interpret the multiple gigabytes of BGP log data, we have developed the "Link-Rank" graphical toolset. Link-Rank weighs the links between autonomous systems by the number of routing prefixes going through each link. Tracing these graphs over time results in a directed graph that shows the weight changes of the logical inter-AS links. From this graph one can easily visualise the complex BGP path changes and also combine views from multiple vantage points, to get a better picture of global routing dynamics. We illustrate the usefulness of Link-Rank by using it to examine BGP routing dynamics in three example cases. These examples show Link-Rank is able to help BGP analysts estimate the scope of routing changes and to reveal important routing dynamics in the presence of superfluous BGP update messages.