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www.caida.org > data : routing : routeviews-prefix2as.xml
Routeviews Prefix to AS mappings Dataset (pfx2as)

Description

This dataset contains IP Prefix to Autonomous System (AS) mappings derived from RouteViews data. Files are created on a daily basis, starting from 2005-05-09. The file format is line-oriented, with one prefix-AS mapping per line. The tab-separated fields are:

  • IP prefix
  • prefix length
  • AS number
More detailed information can be found in the README for this dataset. Files from this dataset can be used by CAIDA's ASFinder and various CoralReef tools (for example in the t2_convert -R option).

Note on Multi-origin ASes (MOASes)

The file format changed slightly beginning with the 2010-10-27 prefix-to-AS file. Previously, ASes were listed in sorted order in MOASes (for example, we said "10_20_30" and never "30_10_20"). Now, we sort the ASes according to their frequency of appearance as an origin AS in the source BGP table. For example, suppose 10.0.0.0/8 is advertised by the ASes 10, 20, and 30, and suppose 7 RouteViews peers saw AS 10 as the origin AS, 4 saw AS 20 as the origin AS, and 29 saw AS 30 as the origin AS. Then the MOAS recorded in the prefix-to-AS file will be 30_10_20, according to descending frequency of appearance as an origin AS. If there is a tie in frequency, then we sort by lexicographical order. With the new sorting order, users who wish to choose "the best" mapping for simplicity (with full understanding of the caveats) can simply pick the first listed AS.

Download Data

Download Routeviews Prefix to AS mappings data.

  Last Modified: Wed Oct-27-2010 15:44:42 PDT
  Page URL: http://www.caida.org/data/routing/routeviews-prefix2as.xml