On the structure and application of BGP policy atoms

The notion of Internet Policy Atoms has been recently introduced in [1], [2] as groups of prefixes sharing a common BGP AS path at any Internet backbone router. In this paper we further research these 'Atoms'. First we offer a new method for computing the Internet policy atoms, and use the RIPE RIS database [6] to derive their structure. Second, we show that atoms remain stable with only about 2-3% of prefixes changing their atom membership in eight hour periods. We support the 'Atomic' nature of the policy atoms by showing BGP update and withdraw notifications carry updates for complete atoms in over 70% of updates, while the complete set of prefixes in an AS is carried in only 21% of updates. We track the locations where atoms are created (first different AS in the AS path going back from the common origin AS) showing 86% are split between the origin AS and it's peers thus supporting the assumption that they are created by policies. Finally applying atoms to "real life" applications we achieve a modest savings in BGP updates due to the low average prefix count in the atoms.