  We investigate a simple model of neutrino mass based on SU(3)_C X SU(3)_L X
U(1)_X gauge unification. The Yukawa coupling of the model has automatic
lepton-number symmetry which is broken only by the self-couplings of the Higgs
boson. At tree level, neutrino spectrum contains three Dirac fermions, one
massless and two degenerate in mass. At the two loop-level, neutrinos obtain
Majorana masses and correct the tree-level result which naturally gives rise to
an inverted hierarchy mass pattern and interesting mixing which can fit the
current data with minor fine-tuning. In another scenarios, one can pick the
scales such that the loop-induced Majorana mass matrix is bigger than the Dirac
one and thus reproduces the usual seesaw mechanism.
