Enabling hierarchical control of coherent pluggable transceivers in SONiC packet–optical nodes

Traditional metro networks are composed of packet switching nodes (i.e., routers) interconnected by optical transport links. In this scenario, the packet and optical domains are clearly separated, using dedicated controllers. Standalone muxponders/transponders will be replaced in optical metro and transport networks by the utilization of hybrid packet–optical nodes equipped with coherent pluggable transceivers. Thus, the traditional packet control plane is unable to manage and fully support the specific optical parameters required to configure such pluggable modules. Moreover, the coordination between the optical and packet layers within this hybrid node has not been standardized yet and requires careful design to enable effective management of connectivity services. This paper proposes two software-defined networking (SDN)-based hierarchical solutions to coordinate and control coherent pluggable transceivers in a multi-layer network exploiting hybrid packet–optical nodes. The two solutions have been designed and validated focusing on the pluggable module configuration and the communication within the SDN hierarchical architecture. An experimental testbed including two packet–optical nodes, running an extended version of the open-source Software for Open Networking in the Cloud (SONiC) operating system, is deployed to show the effectiveness of the two solutions, with a deep analysis of the time required to set up end-to-end connections spanning the packet and optical domains.