Experimental demonstration of a collaborative centralized and distributed control plane for multi-granularity switching in an all-optical metro spine-leaf network

With the rapid growth of “east-to-west” traffic, the future metro network can be viewed as a “hyperscale data center network.” Hybrid optical switching technology enables wavelength and sub-wavelength connectivity for metro-converged services, addressing diverse service requirements. However, the coexistence of such multi-granularity switching resources in the metro network poses new challenges to the network control plane, which is required to provide capabilities including unified management of heterogeneous resources for long-duration services and fast switching for burst services. In this paper, we propose and demonstrate a collaborative centralized and distributed control plane for multi-granularity switching in an all-optical metro spine-leaf network testbed based on an integrated FPGA and an intelligent management and control system. To achieve efficient and lossless fast optical time-slot switching, we propose an optical time-slot alignment mechanism and implement nanosecond-level time synchronization. We also integrate precise frequency synchronization, which serves to reduce the receiver overhead incurred by two consecutive time slots from different sources. Finally, experimental results demonstrate that the proposed control plane implements dynamic control of hybrid optical wavelength and optical time-slot switching, based on programmable centralized and distributed control packets.