Frequency Asked Questions
  1. How often is AS Rank updated?
    AS Rank is under funded and best effort, but we aim for a monthly update.
  2. How are ASes ranked?
    ASNs are ranked in order of the number of ASes in the customer cone, then prefixes if the number of ASes is equal, and then addresses. If these values are all equal they are then ranked by global degree, and then transit degree.
  3. How is prefix and address customer cone defined? How does this affect overall ranking?
    An AS's prefix customer cone is the union of the prefixes announced by the ASes in it's AS customer cone. The address customer cone is the set of addresses contained by the prefixes in it's prefix customer cone. These are used to break ties in the number of ASes in customer cone.
  4. How is AS Rank Calculated?
    The AS rank equals the number of ASes in its customer cone or the number of ASes observed in downstream customer paths from the AS as seen in Route Views or RIPE RIS BGP monitors. For more information see the about.
  5. Can I use this to calculate the geographic distribution of address space?
    No, because prefixes can overlap geographic regions and can map to multiple countries. Also, AS Rank data is not organized by prefix in a way that allows one to simply add them up. To approach this question, we recommend that you start with MaxMind GeoLite. Though not perfect, we believe it to be the best free source for geolocated IP blocks. You can then use the CAIDA AS Organizations dataset to map all the ASes to a country.

    Keeping in mind that large ASes often have presence in multiple countries, and so their address space is located across those countries as well.

  6. How do I improve my ranking?
    Unfortunately given our current customer cone inference algorithm, the best way to increase the number of ASes in your customer cone would be make them more visible to the public route collector projects.

    An AS's customer cone is not inferred directly from it's own paths, but from paths observed in it's providers and peers. Since an AS would only announce paths to it's customer cone to its Providers and Peers, but could announce all paths to its internal monitors or its customers. For the rest of the path, all ASes after an AS in the path are included in its customer cone. You can find more details in the paper "AS Relationships, Customer Cones, and Validation".

    As a result, one way to increase the number of ASes in your customer cone would be to announce more AS Paths to your Peers who provide data to RouteViews or RIPE NCC RIS.

    We are definitely open to other ideas as we really care about the integrity of the inferences, but the sustainability issue is why we need an automated, scalable method to infer the cone, that we could argue was reasonable across all ASes. Please email asrank-feedback@caida.org. Unfortunately we currently do not have funding for additionally functionality, so new features will have to wait until we get additional funding.