  We present a systematic and detailed study of the robustness of directed
networks under random and targeted removal of links. We work with a set of
network models of random and scale free type, generated with specific features
of clustering and assortativity. Various strategies like random deletion of
links, or deletions based on betweenness centrality and degrees of source and
target nodes, are used to breakdown the networks. The robustness of the
networks to the sustained loss of links is studied in terms of the sizes of the
connected components and the inverse path lengths. The effects of clustering
and 2-node degree correlations, on the robustness to attack, are also explored.
We provide specific illustrations of our study on three real-world networks
constructed from protein-protein interactions and from transport data.

Physics and Society