  We investigate the percentage of delivering capacities that are actually
consumed in a typical traffic dynamics where the capacities are uniformly
assigned over a scale-free network. Theoretical analysis, as well as
simulations, reveal that there are a large number of idle nodes under both free
and weak congested state of the network. It is worth noting that there is a
critical value of effective betweenness to classify nodes in the congested
state, below which the node has a constant queue size but above which the queue
size increases with time. We also show that the consumption ratio of delivering
capacities can be boosted to nearly 100% by adopting a proper distribution of
the capacities, which at the same time enhances the network efficiency to the
maximum for the current routing strategy.
