Measuring IP Address Fragmentation from BGP Routing Dynamics

Address Fragmentation plays a key role in the exponential growth of DFZ routing table, known as the scalability problem of current Internet. In this paper, we measure the severity of address fragmentation, and try to figure out the relationship between Prefix-Distance and Network-Distance of current Internet by taking Geographic-Distance as an approximation of NetworkDistance. We focus our measurement on the prefixes with relatively small Geographic-Distance, and get Prefix Groups from BGP routing dynamics. This method reduces the number of active probes required in active measurement, and results a more detailed prefixes’ distribution analysis. We find out that there are two extreme allocations of IP address blocks in current Internet. Some of the blocks with small Geographic-Distances have small Prefix-Distances, while others with small Geographic-Distances have rather big Prefix-Distances. This is the direct reason of the BGP routing table’s inflation. We further conclude that by reallocating IP address blocks according to geography, we could significantly reduce the size of the global routing tables.