  Optical communications and networking are fast becoming the solution to
support ever-increasing data traffic across all segments of the network,
expanding from core/metro networks to 5G/6G front-hauling. Therefore, optical
networks need to evolve towards an efficient exploitation of the infrastructure
by overcoming the closed and aggregated paradigm, to enable apparatus sharing
together with the slicing and separation of the optical data plane from the
optical control. In addition to the advantages in terms of efficiency and cost
reduction, this evolution will increase the network reliability, also allowing
for a fine trade-off between robustness and maximum capacity exploitation. In
this work, an optical network architecture is presented based on the physical
layer digital twin of the optical transport used within a multi-layer
hierarchical control operated by an intent-based network operating system. An
experimental proof of concept is performed on a three node network including up
to 1000 km optical transmission, open re-configurable optical add & drop
multiplexers (ROADMs) and white-box transponders hosting pluggable multi-rate
transceivers. The proposed solution is based on GNPy as optical physical layer
digital twin and ONOS as intent-based network operating system. The reliability
of the optical control decoupled by the data plane functioning is
experimentally demonstrated exploiting GNPy as open lightpath computation
engine and software optical amplifier models derived from the component
characterization. Besides the lightpath deployment exploiting the modulation
format evaluation given a generic traffic request, the architecture reliability
is tested mimicking the use case of an automatic failure recovery from a fiber
cut.
