Attacks and cascades in complex networks

This paper reviews two problems in the security of complex networks: cas- cades of overload failures on nodes and range-based attacks on links. Cascading failures have been reported for numerous networks and refer to the subsequent failure of other parts of the network induced by the failure of or attacks on only a few nodes. We investigate a mechanism leading to cascades of overload failures in complex networks by constructing a simple model incorporating the flow of physical quantities in the network. The second problem is motivated by the fact that most existing works on se- curity of complex networks consider attacks on nodes rather than on links. We address attacks on links. Our investigation leads to the finding that many scale-free networks are more sensitive to attacks on short-range than on long-range links. Besides its im- portance concerning network security, our result has the unexpected implication that the small-world phenomenon in these scale-free networks is mainly due to short-range links.