  Taking into account the fact that overload failures in real-world functional
networks are usually caused by extreme values of temporally fluctuating loads
that exceed the allowable range, we study the robustness of scale-free networks
against cascading overload failures induced by fluctuating loads. In our model,
loads are described by random walkers moving on a network and a node fails when
the number of walkers on the node is beyond the node capacity. Our results
obtained by using the generating function method shows that scale-free networks
are more robust against cascading overload failures than Erd\H{o}s-R\'enyi
random graphs with homogeneous degree distributions. This conclusion is
contrary to that predicted by previous works which neglect the effect of
fluctuations of loads.
