Abstract
BGP routing table growth is one of the major Internet scaling issues, and prefix deaggregation is thought to be a major contributor to table growth. In this work we quantify the fragmentation of the routing table by the type of IP prefix. We observe that the proportion of deaggregated prefixes has quasi doubled in the last fifteen years. Our study also shows that the deaggregated prefixes are the least stable; they appear and disappear more frequently. While we can not see significant differences in path prepending between the categories, deaggregated prefixes do tend to be announced more selectively, indicating traffic engineering. We find cases where lonely prefixes are actually deaggregation in disguise. Indeed, some large transit ISPs advertise many lonely prefixes when they own the covering prefix. We show the extents of this practice that has a negative impact on the routing table even though it could usually be avoided.