OpenConfig and OpenROADM Automation of Operational Modes in Disaggregated Optical Networks

OpenConfig and Open ROADM are emerging as the most relevant initiatives to support partial disaggregation, in which the optical line system is provided by a single vendor while transponders can be provided, in pairs, by different vendors. This way, vendor lock-in is eliminated at the transponder level, without significantly impacting the transmission performance. Although the above initiatives have defined YANG models reaching a good level of maturity, there are still open issues that prevent the full deployment of vendor-neutral partially disaggregated solutions. Among these, the candidate transmission modes in a transponder, including proprietary solutions, are exposed in the YANG models as opaque attributes called Operational (OP) Modes, thus limiting the awareness and the effectiveness of the SDN controller in the selection of the most appropriate transmission mode. In this work, we focus on the open issues related to the configuration and adaptation of transmission parameters. In particular, we focus on the OpenConfig concept of OP Mode enabling the abstraction of transmission complexity but currently preventing an SDN controller to manage transponders in a fully vendor-neutral way. This work first estimates, through a simulative study, the network performance benefit that is achievable by optimizing the OP mode selection. Then, a telemetry-based automated solution is proposed, designed and implemented to enhance the OP mode concept in case of both provisioning and adaptation scenarios (e.g., upon failure), also considering the impact in the tributary/client network. In particular, the following components have been designed and implemented: (i) software agent for Open Config transponders; (ii) software agent for Open ROADM line systems, (iii) an automatic telemetry-assisted monitoring handler; and (iv)SDN control procedures implemented in the ONOS Controller. The proposed components and comprehensive solution have been evaluated in a network testbed encompassing multi-vendor network elements, successfully demonstrating a full vendor-neutral partially disaggregated provisioning and recovery operations.