For optical networks

routing and spectrum allocation are one of the most important problems that restrict the utilization of optical layer resources and the capacity of optical networks. The rapid development of machine learning provides a new direction for the intelligent and automatic management and control of optical network. This paper reviewed the recent research on ML-based routing spectrum allocation

introduced the common ML algorithms in optical network control

described the routing spectrum allocation mechanism based on neural network and reinforcement learning

and finally analyzed the potential challenges in generalization and reliability of current research.