## 3 Internet of Things in Industrial Applications
### Recapitulation of Contemporary Research Developments in the IIoT
This is aimed at developing a novel GA-TBR protocol for optimal selection of routes in WSN smart grid environments. Results obtained showed that the GA-TBR algorithm could select optimal routes with minimum possible delays. More so, a 20% performance improvement is observed when the GA-TBR protocol is compared with the existing IEEE 802.11s (wireless LAN standard for mesh networking) ad-hoc on demand distance vector routing (AODV) protocol. Additionally, the concept of SDN is adopted in [46] for IIoT in the context of smart grid infrastructure, in order to meet the high demands of seamless data transmission during critical events such as natural disturbances or system failures. SDN is a useful technology adopted to enhance the application of IoT in the industry by providing dynamic reconfiguration for the improvement of data network robustness. A new SDN platform is proposed in this paper for IIoT systems in order to support resiliency by reacting immediately whenever a failure occurs. This is fore the recovery of smart grid networks using real-time monitoring techniques. To achieve multi-functionality control and over come the challenges of optimization by operators, a SDN controller is adopted for providing real-time data monitoring in order to manage demand and increase system reliability and resources. The proposed IIoT SDN platform uses a three layer controller namely; _infrastructure layer_, _control layer_ and _application layer_. The physical layer carries all physical equipment and hardware components for route switching performance between the network clusters and SDN switches. The devices contained in this infrastructure layer include smart sensors and actuators, demand response systems (DRS), advance metering infrastructure (AMI) and field bus control. The control layer receives routing information from SDN switches whenever new traffic flows are received by the switches. In other words, it serves as an interface between the application layer and the physical infrastructure. Data path allocation procedures are then allocated by the control layer after which requested paths are processed by the assignment of new routing rules and policies in agreement with the application layer. The application layer is the top most layer of the proposed SDN platform. Services for utility authentication are managed by this layer at the back-end system where information of each service request is exchanged and delivered. Data centers, storage, servers, processing, analysis and applications all constitute the application layer of the SDN platform. Experimental results obtained from this paper revealed that SDN controllers showed great potentials for supporting resilience of smart grids even at faulty situations. The results demonstrated that the dynamic end-to-end reroute can be realized in a few milliseconds, hence SDN-based IIoT systems can significantly improve grid reliability for smart grid resilience enhancement. The bring your own key (BYOK) principle based on near field communication (NFC) is proposed in [41] for mitigating the drawbacks of end-to-end private key cryptography and factory installed keys in the IIoT systems. For confidential and relevant production information to be transmitted over the Internet in industrial systems, appropriate cryptography methods [59] such as end-to-end encryption using transport layer security (TLS) needs to be employed. Asymmetric cryptography provides an end-to-end encryption method that is not feasible in large data applications. Symmetric cryptography on the other hand, can be adopted for this purpose but requires both the sender and receiver to share the same key as a direct connection cannot be established using Message Queue Telemetry Transport (MQTT) protocols and key exchange algorithms such as the Diffie-Hellman cannot be adopted. The proposed BYOK scheme in this paper is used to mitigate these drawbacks where device owners can change keys needed for end-to-end encryption and NFC technology is employed for transferring key materials between devices.