Scalable SDN-based MQTT Real-Time Communications for Edge Networks

MQTT is a widely used application-layer protocol for Internet-of-Things (IoT) and Industrial IoT networks. However, its centralized architecture, which relies on a broker that mediates all data transmissions, can lead to traffic congestion and reduced network capability, particularly in networks with a large number of devices, such as edge networks. This paper proposes an optimized SDN-based real-time MQTT architecture for edge networks, called Multicast Real-Time MQTT (MRT-MQTT) that leverages multicast routing mechanisms to efficiently distribute data while supporting timeliness requirements and minimizing network usage. Extensive emulation experiments show the effectiveness of the proposed approach and its superiority over Direct Multicast-MQTT (DM-MQTT) and Standard MQTT (STD-MQTT). We achieved a reduction in transmission delay of 29% and 23% for QoS=0 and QoS=1, respectively, when compared to DM-MQTT and 55% and 43% compared to STD-MQTT. In this last case, MRT-MQTT also reduced network usage by 58.0% and 45.0% for QoS=0 and QoS=1, respectively.