How do real graphs evolve over time? What are “normal” growth patterns in social, technological, and information networks? Many studies have discovered patterns in static graphs, identifying properties in a single snapshot of a large network, or in a very small number of snapshots; these include heavy tails for in- and out-degree distributions, communities, small-world phenomena, and others. However, given the lack of information about network evolution over long periods, it has been hard to convert these findings into statements about trends over time. Here we study a wide range of real graphs, and we observe some surprising phenomena. First, most of these graphs densify over time, with the number of edges growing superlinearly in the number of nodes. Second, the average distance between nodes often shrinks over time, in contrast to the conventional wisdom that such distance parameters should increase slowly as a function of the number of nodes (like O(log n) orO(log(log n)). Existing graph generation models do not exhibit these types of behavior, even at a qualitative level. We provide a new graph generator, based on a “forest fire” spreading process, that has a simple, intuitive justification, requires very few parameters (like the “flammability” of nodes), and produces graphs exhibiting the full range of properties observed both in prior work and in the present study.

The robustness of the Internet relies heavily on the robustness of BGP routing. BGP is the glue that holds the Internet together: it is the common language of the routers that interconnect networks or Autonomous Systems(AS). The robustness of BGP and our ability to manage it effectively is hampered by the limited global knowledge and lack of coordination between Autonomous Systems. One of the few efforts to develop a globally analyzable and secure Internet is the creation of the Internet Routing Registries (IRRs). IRRs provide a voluntary detailed repository of BGP policy information. The IRR effort has not reached its full potential because of two reasons: a) extracting useful information is far from trivial, and b) its accuracy of the data is uncertain.

The robustness of the Internet relies heavily on the robustness of BGP routing. BGP is the glue that holds the Internet together: it is the common language of the routers that interconnect networks or Autonomous Systems(AS). The robustness of BGP and our ability to manage it effectively is hampered by the limited global knowledge and lack of coordination between Autonomous Systems. One of the few efforts to develop a globally analyzable and secure Internet is the creation of the Internet Routing Registries (IRRs). IRRs provide a voluntary detailed repository of BGP policy information. The IRR effort has not reached its full potential because of two reasons: a) extracting useful information is far from trivial, and b) its accuracy of the data is uncertain.