Flattening and preferential attachment in the internet evolution

Understanding of the Internet evolution is important for many research topics, such as network planning, optimal routing design, etc. In this paper, we try to analyze CAIDA AS-level topology dataset from 2004 to 2010 to validate two conjectures on the Internet evolution, i.e., the Internet flattening trend and the preferential attachment rule. Our analysis shows that the evolvement of the Internet core is different from the edge of Internet. We classify the Internet into several layers using different layering methods, i.e., Rich Club coefficient based method, k-core decomposition method and SARK hierarchy model, and then study the changes of the features of these layers. Under all of these laying methods, we find that the boundaries between neighboring layers in the Internet core are more and more blurred; ASes in the core distribute more evenly and different layers are closer to each other in size, while the Internet edge still has a distinct hierarchical characteristic. It is more evident in Asia and Europe than North America. The other difference between Internet core and Internet edge is that link births/deaths in the Internet core follow the “Preferential Attachment/de-attachment” rule, while link births/deaths in the Internet edge follow a super linear preferential attachment/de-attachement rule. On the other hand, in both Internet core and Internet edge, link births caused by AS births present stronger preference than link rewiring.