  Filterless optical transport networks relies on passive optical
interconnections between nodes, i.e., on splitters/couplers and amplifiers.
While different studies have investigated their design, none of them offer a
solution for an optimal design. We propose a one step solution scheme, which
combines network provisioning, i.e., routing and wavelength assignment within a
single mathematical model. Decomposition into two different types sub-problems
is then used in order to conceive an exact solution scheme. The first type of
subproblem relies on the generation of filterless subnetworks while the second
one takes care of their wavelength assignment.
  Numerical experiments demonstrate the improved performance of the proposed
optimization model and algorithm over the state of the art, with the
improvement of the solution for several open source data sets.
