BEXCO - Room F(201/202/203/204)
[NU134] The Software Defined Networks implementation for the KM3NeT networking infrastructure
KM3NeT is a distributed neutrino observatory in the abyssal site of the Mediterranean Sea. Each installation is based on a grid of thousands Digital Optical Modules (DOMs), interconnected to shore via an electro-optical seafloor infrastructure. The DOMs are organised in vertical structures, each one provided with a base-module for controlling the power supply and optical amplification of the attached devices. The DOMs and base-modules are submarine nodes of the global Layer 2 optical networking infrastructure, which has an asymmetric layout. Slow control and time synchronisation information are sent from shore through a single optical channel, mirrored underwater up to each endpoint. On the contrary, each DOM and base-module use a dedicated connection for transmitting data to shore. The Software Defined Networks technology is used to configure and operate the core of the switch fabric, organised according to a star-center layout and interconnecting all the on-shore resources. The used switches are DELL Series S devices, compatible with the OpenFlow 1.3 protocol and managed by dedicated OpenDaylight 4.2 (Berillium) controller servers. With a limited number of Layer 2 forwarding rules, expressly developed for the KM3NeT use-case, which keeps independent from any scaling of the off-shore detector, i.e. from the number of DOMs, the SDN technology allows the best handling of the KM3NeT asymmetric network topology, optimising the layout of connections on shore, preventing loops and enhancing the data taking stability.