# Application-Aware SDN-Based Iterative Reconfigurable Routing Protocol for Internet of Things (IoT)
## 3 Related Work  
In existing parallel literature of WSNs, the design of internet of things (IoT) is constructed in which hundreds and thousands of sensor nodes perform suitable interconnection to proceed the sensing and monitoring processes. As, existing conventional architectures of WSNs inherent many challenges due to the fragile distributed management system, similarly IoT face identical issues of nodes resource constraints of heterogeneity-limitations and application-awareness [19]. These issues are highlighted by the widening of the recent market for sophisticated applications at a larger scale networking range of density. Conventional WSNs struggles as deployed nodes are not reprogrammable, which makes nodes responsible for the basic operations such as data forwarding and network control, and this makes the node behave ultimately like an autonomous system [20]. These technical limitations result in a lack of cognitive flexibility to manage advanced-level quality application-awareness. With the development of effective WSNs networking new mechanisms, it is essential to promote the central management systems for maintenance and resource-effective connectivity. The system needs to be continuous variation in reconfigurations of nodes with a limited lifetime. New configuration settings of WSNs faces this challenge where the data packets and the control packets are transmitted through the existing network bandwidth [21; 22]. Industrial demands for a better success rate of IoT insists the researchers to investigate the opportunities promised by SDN proposed solutions to develop flexible management of IoT that separate the control logic from the network nodes or actuators. These advanced features of SDN-based central management of WSNs architectures are attractive enough to gain researchers' attention as SDN-based management systems are being developed for every type of mainframe networks [23]. SDN-based central management systems provide immense flexibilities to develop and exercise the overall network management protocols and their applications. Consequently, the IoT nodes are capable of reprogrammable in case of priority operations [24]. To this end, the various researchers investigate and proposed solutions to manage the IoT networks parallel to WSNs, and some of these solutions are designed through the (SDN). In contrast with conventional WSNs management systems, SDN-based WSNs offer real-time reconfigurations to achieve network configuration optimization and application-sensitive environmental sensing. Consequently, new traffic engineering protocols need to be developed to support real-time reconfigurations to utilize application-specific platform-independent central control with the help of SDN central controller. The evolution of SDN-based WSNs architecture is a recent development, and advanced protocols are under construction [25]. In light of resource constraints of WSNs, routing protocols are being proposed to offer SDN-based WSNs inter-networking. The available routing protocols which are introduced in the past few years are discussed below:  
* Situation-Aware Routing Protocol Switching for SDN-based WSNs: In [26], Situation-aware routing protocol switching scheme has been introduced, which design a platform-independent architecture to implement multiple routing protocols for SDN-based WSNs. This situation-aware switching mechanism allows the network operators to not only reconfiguration of application-specific sensing attributes but also provide flexibility to change routing protocol in real-time. This SDN-based WSNs routing modeling solution divides its working into phases; in the initial stage, central control compute network resources according to current network topology and decide for specific routing protocol should be implemented. Whereas, in the second phase, the central controller performs reconfiguration of sensor nodes according to selected routing protocol and dictates nodes to report according to the current network settings.