  We revisit the diffusion properties and the mean drift induced by an external
field of a random walk process in a class of branched structures, as the comb
lattice and the linear chains of plaquettes. A simple treatment based on
scaling arguments is able to predict the correct anomalous regime for different
topologies. In addition, we show that even in the presence of anomalous
diffusion, Einstein's relation still holds, implying a proportionality between
the mean square displacement of the unperturbed systems and the drift induced
by an external forcing.
