In order to meet various bandwidth requirements, such as sub-wavelength and super-wavelength, and overcome the
power consumption bottleneck, dynamic flexible optical networks have become the middle term solution of all optical
networks instead of optical packet switching (OPS) networks. Different from routing and wavelength assignment (RWA)
in WDM networks, routing and spectrum assignment (RSA) in dynamic flexible optical networks faces more constraints,
which are summarized as three-C constraints, i.e. Continuity, Consistency, and re-Configurability. Routing and spectrum
assignment problem in three-C-aware dynamic flexible optical networks is mainly investigated in the paper.
Keywords: Flexible optical networks, three-C, routing and spectrum assignment, defragmentation.