  Passive optical networks (PON) can play a vital role in data centres and
access fog solutions by providing scalable, cost and energy efficient
architectures. This paper proposes a Mixed Integer Linear Programming (MILP)
model to optimize the placement of virtual machines (VMs) over an energy
efficient WDM-TDM AWGR PON based data centre architecture. In this
optimization, the use of VMs and their requirements affect the optimum number
of servers utilized in the data centre when minimizing the power consumption
and enabling more efficient utilization of servers is considered. Two power
consumption minimization objectives were examined for up to 20 VMs with
different computing and networking requirements. The results indicate that
considering the minimization of the processing and networking power consumption
in the allocation of VMs in the WDM-TDM AWGR PON can reduce the networking
power consumption by up to 70% compared to the minimization of the processing
power consumption.
