Abstract
Network function virtualization (NFV) and software-defined networking (SDN) are two technologies that have emerged to reduce capital and operational costs, and to simplify network management. In this paper, we propose an SDN-based system that provisions virtual network functions (VNFs) to minimize round trip time (RTT) delay and synchronization delay requirements. Our system uses graphic-theoretic approaches to place newly requested VNFs including four centrality functions - betweenness, degree, closeness, and Katz. The system performance is evaluated using two random graph topologies representing the physical and logical structures. The impact of increasing the number of deployed VNFs is considered. The results indicate that the degree and Katz selection methods mostly provide the minimum RTT for physical networks, whereas the betweenness selection provides minimum RTT values for logical networks. Moreover, the closeness selection method provides the best synchronization delay for both logical and physical networks.