  Anomalous Hall effect in very clean samples (high conductivity regime) is
studied using a two-dimensional network model. We find that the off-diagonal
conductivity comprises two parts: one which reflects the bulk properties as
obtained by the Kubo formula and another which is sensitive to boundary
conditions imposed on the network. The latter scales with the system width in
the ideal case and for real-world samples, it will depend on the coherence
length. It provides an alternative interpretation of the observed behaviour in
the clean limit which is otherwise attributed to the skew scattering. We
highlight analogies to friction in viscous fluids responsible for Couette flow.
