Characterizing and analysis of the flattening Internet topology

Despite significant efforts to qualitatively describe the flattening trends of the Internet topology, there is few large-scale quantitative measurement study of such trends from the perspective of inter-domain routing. In this paper, we analyze the evolutionary trends of the Internet hierarchy and the interconnection policies, using fifteen years of historical datasets from RouteViews and RIPE. We find that the Internet is becoming flatter mainly due to bypassing the Tier-1 ISPs on AS-paths and the notable increase of peer-to-peer links. We also examine the global routing infrastructure, and find that IXPs are increasing rapidly in number and expand to broad areas around the world, which greatly facilitates the expansion of major content providers and content delivery networks to most regions in the world. Finally we discuss the impact and implication of this trend. Our measurement results strongly confirm the flattening trends of the Internet, and will help advance our understanding of the Internet AS-level ecosystem and the design of future Internet architecture.