The "robust yet fragile" nature of the Internet
The search for unifying properties of complex networks is popular, challenging, and important. For modeling approaches that focus on robustness and fragility as unifying concepts, the Internet is an especially attractive case study, mainly because its applications are ubiquitous and pervasive, and widely available expositions exist at every level of detail. Nevertheless, alternative approaches to modeling the Internet often make extremely different assumptions and derive opposite conclusions about fundamental properties of one and the same system. Fortunately, a detailed understanding of Internet technology combined with a unique ability to measure the network means that these differences can be understood thoroughly and resolved unambiguously. This article aims to make recent results of this process accessible beyond Internet specialists to the broader scientific community and to clarify several sources of basic methodological differences that are relevant beyond either the Internet or the two specific approaches focused on here (i.e., scale-free networks and highly optimized tolerance networks).
Freely available online through the PNAS open access option. Edited by Robert M. May, University of Oxford, Oxford, United Kingdom and approved August 29, 2005 (received for review February 18, 2005). Published online before print October 4, 2005, 10.1073/pnas.0501426102 This work was partially supported by Boeing, Army Institute for Collaborative Biotechnologies, an Air Force Office of Scientific Research Award FA9550-05-1-0032 ''Bio-Inspired Networks,'' and the Lee Center for Advanced Networking (California Institute of Technology). Parts of this work were done at the Institute of Pure and Applied Mathematics (University of California, Los Angeles) as part of the 2002 annual program on large-scale communication networks. Author contributions: J.C.D., D.L.A., and W.W. designed research; J.C.D., D.L.A., L.L., R.T., and W.W. performed research; J.C.D., D.L.A., L.L., and W.W. contributed new reagents/analytic tools; J.C.D., D.L.A., L.L., and W.W. analyzed data; J.C.D., D.L.A., W.W. wrote the paper; S.S. facilitated access and analysis of Abilene network data; and S.L., M.R., and S.S. contributed to the understanding of network backbone design. This paper was submitted directly (Track II) to the PNAS office. Detailed information about the objectives, organization, and development of the Abilene network are available from www.internet2.edu/abilene. SKITTER Project. Cooperative Association for Internet Data Analysis, University of California San Diego Supercomputing Center (www.caida.org).
Published - DOYpnas05.pdf