Phase Changes in the Evolution of the IPv4 and IPv6 AS-Level Internet Topologies

In this paper we investigate the evolution of the IPv4 and IPv6 Internet topologies at the autonomous system (AS) level over a long period of time.We provide abundant empirical evidence that there is a phase transition in the growth trend of the two networks. For the IPv4 network, the phase change occurred in 2001. Before then the network's size grew exponentially, and thereafter it followed a linear growth. Changes are also observed around the same time for the maximum node degree, the average node degree and the average shortest path length. For the IPv6 network, the phase change occurred in late 2006. It is notable that the observed phase transitions in the two networks are different, for example the size of IPv6 network initially grew linearly and then shifted to an exponential growth. Our results show that following decades of rapid expansion up to the beginning of this century, the IPv4 network has now evolved into a mature, steady stage characterised by a relatively slow growth with a stable network structure; whereas the IPv6 network, after a slow startup process, has just taken off to a full speed growth. We also provide insight into the possible impact of IPv6-over-IPv4 tunneling deployment scheme on the evolution of the IPv6 network. The Internet topology generators so far are based on an inexplicit assumption that the evolution of Internet follows non-changing dynamic mechanisms. This assumption, however, is invalidated by our results.Our work reveals insights into the Internet evolution and provides inputs to future AS-Level Internet models.Comment: 12 pages, 21 figures; G. Zhang et al.,Phase changes in the evolution of the IPv4 and IPv6 AS-Level Internet topologies, Comput. Commun. (2010

A Structural Analysis of the Internet AS-level topology

The study of the structural characteristics of the Internet topology at the Autonomous System (AS) level of abstraction is an important and interesting subject that has attracted significant interest over the last few years. Above all, a deep knowledge of the Internet underlying structure helps researchers in designing a more accurate model of the network; as a result, engineers can design applications and protocols that can take into account the underlying structure and test their projects on synthetic graphs, thereby developing more efficient algorithms. A significant challenge for researchers analyzing the Internet is how to interpret the global organization of the graph as the coexistence of its structural blocks associated with more highly interconnected parts, namely communities. While a huge number of papers have already been published on the issue of community detection, very little attention has so far been devoted to the discovery and interpretation of Internet communities. The contribution of this work is twofold. First, we study the evolution of the Internet AS-level topology over the last 9 years by means of two innovative approaches: the k-dense method and the dK-analysis. Second, we focus on substructures that play a key role in the Internet connectivity, and we investigate the classes of the ASes and the nature of the connections that create such communities. We find that as the Internet grows over time, some of its structural properties remain unchanged. Although the size of the network, as well as the kMAX -dense index (an index of the maximum level of density reached in a network), has doubled over the last 9 years, we show that after proper normalizations the k-dense decomposition has remained stable. Besides, we provided a clear evidence that the formation of denser and denser sub-graphs over time has been triggered by the proliferation of Internet eXchange Points (IXP) and public peering connections. We found that ASes within most densely-connected substructures are usually Network Service Providers, Content Providers, or Content Delivery Networks; in addition, all of them participate to at least one IXP

A Brave New World: Studies on the Deployment and Security of the Emerging IPv6 Internet.

Recent IPv4 address exhaustion events are ushering in a new era of rapid transition to the next generation Internet protocol---IPv6. Via Internet-scale experiments and data analysis, this dissertation characterizes the adoption and security of the emerging IPv6 network. The work includes three studies, each the largest of its kind, examining various facets of the new network protocol's deployment, routing maturity, and security. The first study provides an analysis of ten years of IPv6 deployment data, including quantifying twelve metrics across ten global-scale datasets, and affording a holistic understanding of the state and recent progress of the IPv6 transition. Based on cross-dataset analysis of relative global adoption rates and across features of the protocol, we find evidence of a marked shift in the pace and nature of adoption in recent years and observe that higher-level metrics of adoption lag lower-level metrics. Next, a network telescope study covering the IPv6 address space of the majority of allocated networks provides insight into the early state of IPv6 routing. Our analyses suggest that routing of average IPv6 prefixes is less stable than that of IPv4. This instability is responsible for the majority of the captured misdirected IPv6 traffic. Observed dark (unallocated destination) IPv6 traffic shows substantial differences from the unwanted traffic seen in IPv4---in both character and scale. Finally, a third study examines the state of IPv6 network security policy. We tested a sample of 25 thousand routers and 520 thousand servers against sets of TCP and UDP ports commonly targeted by attackers. We found systemic discrepancies between intended security policy---as codified in IPv4---and deployed IPv6 policy. Such lapses in ensuring that the IPv6 network is properly managed and secured are leaving thousands of important devices more vulnerable to attack than before IPv6 was enabled. Taken together, findings from our three studies suggest that IPv6 has reached a level and pace of adoption, and shows patterns of use, that indicates serious production employment of the protocol on a broad scale. However, weaker IPv6 routing and security are evident, and these are leaving early dual-stack networks less robust than the IPv4 networks they augment.PhDComputer Science and EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/120689/1/jczyz_1.pd