Control, Management, and Orchestration of Optical Networks: Evolution, Trends, and Challenges

Automating the provisioning of telecommunications services, deployed over a heterogeneous infrastructure (in terms of domains, technologies, and management platforms), remains a complex task, yet driven by the constant need to reduce costs and service deployment time. This is more so, when such services are increasingly conceived around interconnected functions and require allocation of computing, storage, and networking resources. This automation drives the development of service and resource orchestration platforms that extend, integrate, and build on top of existing approaches, macroscopically adopting software-defined networking principles, leveraging programmability, and open control in view of interoperability. Such systems are combining centralized and distributed elements, integrating platforms whose development may happen independently and parallel, and are constantly adapting to ever changing requirements, such as virtualization and slicing. Of specific interest is the (optical) transport network segment, traditionally operated independently via closed proprietary systems, and characterized by being relatively complex and hard to reach consensus regarding modeling and abstraction. In view of the targets, the transport network segment needs to be integrated into such service orchestration platforms efficiently. In this context, this paper aims at providing an introduction to control, management, and orchestration systems, of which the network control is a core component, along their main drivers, key benefits, and functional/protocol architectures. It covers multidomain and multilayer networks and includes complex use cases, challenges and current trends such as joint cloud/network orchestration and 5G network slicing.