Quantifying the Completeness of the Observed Internet AS-level Structure

Despite significant efforts to obtain an accurate picture of structure at the level of individual autonomous systems (ASes), much remains unknown in terms of the quality of the inferred AS maps that have been widely used by the research community. Building upon our recent results reported in [16], in this paper we take a first step towards quantifying the (in)completeness of the observed AS-level connectivity as seen by the commonly-used vantage points of RouteViews and RIPE-RIS. Calling the current set of vantage points the “public view,” we developed a new heuristic to identify all the ASes whose AS-level connectivity is completely captured by the public view. Our results indicate that the public view is capable of revealing the full connectivity of only 4% of all the ASes, which accounts for 77% of all large ISPs and 34% of small ISPs, but only 0.5% of stub ASes. For the remaining 96% ASes, the public view captures their customerprovider links, but may miss most of their peer links. We also provide evidences that the bulk of the missing connectivity involves peer links below the line of sight of the public view, typically between stub ASes and small ISPs as well as among stub ASes. Our findings call for new ways of inferring AS-level connectivity that do not rely solely on the use of active/passive measurements from vantage points, and our preliminary results towards this direction look promising.