  In this paper, we propose incorporating Optical Wireless Communication (OWC)
and Passive Optical Network (PON) technologies into next generation
spine-and-leaf Data Centre Networks (DCNs). In this work, OWC systems are used
to connect the Data Centre (DC) racks through Wavelength Division Multiplexing
(WDM) Infrared (IR) transceivers. The transceivers are placed on top of the
racks and at distributed Access Points (APs) in the ceiling. Each transceiver
on a rack is connected to a leaf switch that connects the servers within the
rack. We replace the spine switches by Optical Line Terminal (OLT) and Network
Interface Cards (NIC) in the APs to achieve the desired connectivity. We
benchmark the power consumption of the proposed OWC-PON-based spine-and-leaf DC
against traditional spine-and-leaf DC and report 46% reduction in the power
consumption when considering eight racks.
