Dynamic Efficient Routing Protocol (D-ERP) under congestion and O&M switch failures in hybrid SDN-IIoT fog networks

In the era of the Internet of Things (IoT) and Software-Defined Networking (SDN), efficient traffic engineering and resource management are essential for large-scale Industrial IoT (IIoT) systems operating over heterogeneous wired and wireless infrastructures. This paper addresses the challenges of migration of traditional switch to openflow switch replacement strategy, dynamic path computation, congestion avoidance, and routing optimization in SDN-enabled fog-server-core IIoT networks. We propose an SDN-assisted dynamic efficient routing protocol (DERP) based on the Theta* pathfinding algorithm to optimize routing decisions across hybrid environments in peak-time and also employ the replacement strategy algorithm for traditional network upgradation to SDN. The proposed approach is evaluated over network topologies ranging from 15 to 120 nodes and compared against the conventional Dijkstra-based routing algorithm. Experimental results show that the proposed protocol reduces the total path cost by an average of 16% while maintaining comparable computational efficiency with processing times below 25 ms. Furthermore, DERP improves path efficiency by approximately 18% and achieves minimum energy consumption and congestion exposure comparable to Dijkstra-based routing. A key advantage of the proposed method is its ability to exploit line-of-sight wireless connectivity in approximately 40% of routing decisions, enabling more direct communication paths and reducing multi-hop forwarding. These results demonstrate that the proposed SDN-DERP routing effectively enhances performance and supports latency-sensitive IIoT applications in hybrid SDN wired-wireless fog networks.