Software Defined Networking (SDN) emphasizes the separation of data and control plane while network function virtualization (NFV) decouples network function 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 aims to carry out analytical modeling of SDN with NFV under or aside the controller. We model and analyze these two SDN+NFV architectures using M/M/1 queuing model and validate our analysis with various simulations. Results show that the analytical results well match the simulation results. Also a packet delay reduction of 54.67% can be achieved for NFV-AC over NFV-C, meaning that NFV-AC is a better architecture for integrating SDN with NFV.