An Analysis of BGP Routing Table Evolution

In addition to the ever growing host population, multiple other factors have contributed to the rapid growth of the global Internet routing table, such as policy routing, multihoming, and traffic steering. In this paper we first sort the routing table entries into two broad classes, covering prefixes which represent IP address blocks that do not overlap, either partially or completely, with the address block represented by any other entry in the routing table, and covered prefixes, commonly referred to as ”holes”, which represent sub-blocks of those address blocks that are already represented by some shorter prefixes in the routing table. We then develop a classification methodology by identifying the different ways each covered prefix is announced to the global routing system. We inferred the causes of each covered prefix class and identified possible motives for the fragmentation of covering prefixes. Based on our analysis, we provide an empirical model of the global routing table growth by taking into account all the major factors that have been identified in this study.