Techniques for providing closed-loop control and predictive analytics in packet-optical networks are described. For example, an integrated centralized controller is described that provides tightly-integrated, closed-loop control over components of a routing / switching network (e.g., IP/MPLS) and also the underling optical transport system, including routing wavelength and spectrum assignment. The controller adaptively and proactively maps packet flows into network resources of a routing / switching network and control, based on the mapping, allocation and utilization of optical spectrum and wavelengths within the optical transport system underlying the routing and switching network.