In both, metropolitan optical networks (MON) and long haul optical networks (LHON)
the signal quality is often influenced by the physical impairments,
impairment constrained routing decisions are needed.
In this paper we propose two new approaches that jointly perform, on the one hand,
routing and wavelength assignment (RWA) and, on the other hand, either
tuning the signal power of
certain Wavelength Division Multiplexed (WDM) channels or grooming the traffic of
some WDM channels in nodes that are grooming capable.
We evaluate the proposed optimization methods for both, single and multilayer networks.
In the first case we assume that
no signal regeneration is allowed along the path, only reamplification, while in the
more complex two-layer case we assume grooming in the electronic layer
that implicitly performs
3R signal regeneration and wavelength conversion as well.