This paper proposes a novel architecture named SBR, a software defined network (SDN) architecture using as a routing protocol RPL, a Protocol for Low-Power, and Lossy Networks for Internet of Things (IoT). The architecture includes the function SIGMA, an objective function used in IoT applications to take routing decisions. This research represents an effort to relate IoT and SDN. This association was developed using RPL-SIGMA to solve various IoT and Wireless Sensor Networks (WSN) problems. At the end, a comparison between SBR (SDN-RPL with SIGMA) and SDN-RPL (without SIGMA) was included. The simulations show that SBR has a better performance concerning packet loss, latency, and energy consumption over an architecture based on IoT without SIGMA. The simulation also demonstrates that SDN can be used to manage the IoT network efficiently.