Shaping physical machine topology in distributed data center networks

Physical machines (PMs) constitute the hardware infrastructure in data centers. Proper distribution and placement of PMs plays an important role in determining the system performance. Existing PM placement approaches generally ignore the demands of virtual machines (VMs), resulting in a poor resource utilization and service QoS. In this paper, we focus on the PM placement problem in a given optical network (called the optical layer) with given traffic demands on the VM-layer. By jointly considering optical and VM layers, we formulate an ILP (Integer Linear Program) to shape the PM-layer topology, while minimizing the overall cost of PM placement and VM mapping. To combine delay and transmission costs on each optical link, we define a cost factor θ, which can be used to adjust the impact of service delay. Extensive numerical simulations are carried out to validate the correctness of our ILP and the flexibility of our scheme.