We study how the graph structure of the Internet at the Autonomous Systems\n(AS) level evolved during a decade. For each year of the period 2008-2017 we\nconsider a snapshot of the AS graph and examine how many features related\nto structure, connectivity and centrality changed over time. The analysis of\nthese metrics provides topological and data traffic information and allows to\nclarify some assumptions about the models concerning the evolution of the\nInternet graph structure. We find that the size of the Internet roughly\ndoubled. The overall trend of the average connectivity is an increase over\ntime, while that of the shortest path length is a decrease over time. The internal\ncore of the Internet is composed of a small fraction of big AS and is more\nstable and connected the external cores. A hierarchical organization emerges\nwhere a small fraction of big hubs are connected to many regions with high\ninternal cohesiveness, poorly connected among them and containing AS with\nlow and medium numbers of links. Centrality measurements indicate that the\naverage number of shortest paths crossing an AS or containing a link between\ntwo of them decreased over time.
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