  We consider the relation of mixed global gauge gravitational anomalies and
boundary conformal field theory in WZW models for simple Lie groups. The
discrete symmetries of consideration are the centers of the simple Lie groups.
These mixed anomalies prevent to gauge them i.e, take the orbifold by the
center. The absence of anomalies impose conditions on the levels of WZW models.
Next, we study the conformal boundary conditions for the original theories. We
consider the existence of a conformal boundary state invariant under the action
of the center. This also gives conditions on the levels of WZW models. By
considering the combined action of the center and charge conjugation on
boundary states, we reproduce the condition obtained in the orbifold analysis.
