  In this paper, we study the effect of a single link on the capacity of a
network of error-free bit pipes. More precisely, we study the change in network
capacity that results when we remove a single link of capacity $\delta$. In a
recent result, we proved that if all the sources are directly available to a
single super-source node, then removing a link of capacity $\delta$ cannot
change the capacity region of the network by more than $\delta$ in each
dimension. In this paper, we extend this result to the case of multi-source,
multi-sink networks for some special network topologies.
