Performance modeling and comparison of NFV integrated with SDN: Under or aside?

Software Defined Networking (SDN) focuses on the separation of data and control plane, while network function virtualization (NFV) decouples network functions from underlying hardware. Combining SDN with NFV would have many benefits, but the problem is how to integrate them. There are two possible architectures for such integration: the controller interacts with virtualized network functions (VNFs), or the switch interacts with VNFs. In this paper, the former is referred to as NFV under the controller (NFV_C) while the latter is called NFV aside the controller (NFV_AC). To the best of our knowledge, there is no analytical model for mathematically investigating the performance of such architectures. This paper therefore reports on the analytical modeling of SDN with NFV under or aside the controller. We model and analyze these two SDN + NFV architectures using an M/M/1 queuing model and validate our analysis with various simulations. We show that the analytical results match the simulation results very well. Furthermore, a packet delay reduction of 68.83% can be achieved for NFV_AC over NFV_C, meaning that NFV_AC is a better architecture for integrating SDN with NFV. We also consider feedback from the VNF to the switch. For low loads there is delay increase of 35.42% for high feedback (90%) in comparison with low feedback (10%). In the case of high loads we recorded a delay increase of 66.64%.