Collecting Self-reported Semantics of BGP Communities and Investigating Their Consistency with Real-world Usage

People can extract various kinds of information about the Internet from BGP routes tagged with BGP community values with known semantics. In this paper, we conduct a study on the following three issues related to BGP community semantics. First, we design a method to automatically collect self-reported semantics from the Internet and assemble the collected semantics described in natural language into a structured dictionary. The comparison with prior dictionaries shows many community values are exclusively covered by ours and many of them had been used when prior dictionaries were constructed, which confirms the effectiveness of our method. Second, based on this large-size dictionary, we are able to re-evaluate two recent algorithms designed for categorizing community values with unknown semantics, which is a task that, while easier than inferring the detailed semantics, is also very valuable. Our evaluation uncovers some issues within the algorithms that can contribute to their performance improvement. Third, we investigate the fundamental issue in extracting information using community semantics: whether ISPs' behavior is consistent with the published semantics. Our preliminary best-effort investigation reveals the potential risks of using the semantics of some categories of community values.