Locally automated restoration in SDN disaggregated networks

Multi-vendor interoperability and disaggregation are attracting the interest of network operators as a way to avoid vendor lock-in, thus opening the market and, possibly, reducing costs. NETCONF, in concert with YANG data models, has been identified as the software defined networking (SDN) configuration protocol for these networks. Currently, several YANG models describe devices in a vendor-neutral way; however, there is a lack of YANG models describing functions. Moreover, the centralization of the control plane may suffer from scalability issues during critical situations (e.g., link failures), given that several restoration requests will arrive at the SDN controller close in time. This paper investigates an innovative paradigm of restoration for disaggregated SDN networks named delegated restoration, which operates in a hybrid centralized–distributed manner. Before a failure occurs, the backup lightpath is centrally computed by the SDN controller, and, based on this computation, the controller informs the network devices (switches and transponders), through NETCONF, of the reconfigurations to perform in case of failure. Simulations show that delegated restoration can reduce the restoration time with respect to a fully centralized approach, making it a candidate for impacting the operation, administration, and maintenance of next-generation networks.