NEPTUNE gigabit Ethernet submarine cable system

The NEPTUNE scientific submarine cable system will "wire" the Juan de Fuca tectonic plate and turn it into an interactive ocean sciences laboratory. NEPTUNE will provide 30 seafloor nodes distributed over a 500 by 1000 km area to which many scientific instruments may be attached. The NEPTUNE backbone communications system will be based on commercial off-the-shelf Gigabit Ethernet components packaged as ocean bottom communications modules. This paper describes the requirements and technological alternatives that lead to this choice. In addition to the high speed communications needs, separate low-speed channels are required for out-of-band management and the distribution of high accuracy, low jitter time information. A proposed design that meets these two functions is presented. Finally, NEPTUNE instrument communications will be based on slow/fast Ethernet, and a Scientific Instrument Interface Module (SIIM) will be provided to facilitate connection.