Cascading Failure Tolerance of Modular Small-World Networks

Many real-world networks have a modular structure, and their component may undergo random errors and/or intentional attacks. More devastating situations may happen if the network components have a limited load capacity; the errors and attacks may lead to a cascading component removal process, and consequently, the network may lose its desired performance. In this brief, we investigate the tolerance of cascading errors and attacks in modular small-world networks. This brief studies the size of the largest connected component of the networks when cascading errors or attacks occur. The robustness of the network is tested as a function of both the intermodular connection and intramodular rewiring probabilities, i.e., the rewiring probability of original Watts-Strogatz networks that the individual modules are based on. We find that intermodular connections play an important role in determining the robustness of the networks against cascading failures. We also study cascaded failure in a number of real networks with different modularity levels and find that the more the modularity level of a network, the less its robustness against cascaded failures.