Placement of virtual network functions in hybrid data center networks

Hybrid data center networks (HDCNs), where each ToR switch is installed with a directional antenna, emerge as a candidate helping alleviate the over-subscription problem in traditional data centers. Meanwhile, as virtualization techniques develop rapidly, there is a trend that traditional network functions that are implemented in hardware will also be virtualized into virtual machines. However, how to place virtual network functions (VNFs) into data centers to meet the customer requirements in a hybrid data center network environment is a challenging problem. In this paper, we study the VNF placement in hybrid data center networks, and provide a joint VNF placement and antenna scheduling model. We further simplify it to a mixed integer programming (MIP) problem. Due to the hardness of a MIP problem, we develop a heuristic algorithm to solve it. To the best of our knowledge, this is the first work concerning VNF placement in the context of HDCNs. Our extensive simulations demonstrate the effectiveness of the proposed algorithm, which make it a very suitable and promising solution for VNF placement in HDCN environment.