# Application-Aware SDN-Based Iterative Reconfigurable Routing Protocol for Internet of Things (IoT)
## 3 Related Work
Although this routing switching environment is a valuable contribution for SDN-based WSNs solutions, this scheme just considering the existing state-of-the-art routing protocols such as AODV, DSDV, LSR, and DLSR, this solution lacks the proposal of novelty routing protocol; meanwhile, AODV, DSDV, LSR, and DLSR routing protocols are not designed for SDN-based WSNs, so the required performance is still a challenge for this solution. * Non-linear Weight Particle Swarm Optimization (NWPSO) algorithm-based routing protocol: In [27], the authors proposed a routing protocol based upon Non-linear Weight Particle Swarm Optimization (NWPSO) algorithm to implement centralized multi-tasking for SDN-based WSNs (SDWSNs). This protocol develops the clustering mechanism of selecting suitable controllers from the sensor nodes with maximum residual energy, and these controller nodes are responsible for collecting reports at the intra-cluster communication level. NWPSO algorithm functionality is utilized to select the most suitable cluster's controller to assign multi-tasking and inter-cluster communication. The association phase of this routing protocol is similar to conventional routing protocols of WSNs. This routing protocol shows performance betterman LEACH routing protocol, but it lacks to propose classical SDN penetration in WSNs. * QoS-aware routing mechanism for OpenFlow-enabled WSNs: In [28], a unique QoS-aware routing mechanism for OpenFlow-enabled WSNs routing protocol is proposed. Similar to NWPSO, this proposed model also selects some OpenFlow to enable nodes as intermediate nodes to transmits network reports to BS. This routing protocol enhances QoS by choosing the most strong links called a feasible path and then also define the best effort paths. In most of the cases, it is supposed that possible ways will carry transmissions. In case of any unexpected failures of feasible paths, the best effort paths will carry on the network operation. If no path satisfies the required QoS, the road will be decided by the proposed algorithms depending on flow types: delay-sensitive, bandwidth-sensitive, and best-effort traffic. This proposal also only provide an abstract footprint for SDN-based WSNs and also highlight future restrictions. * SDN Enabled SPIN Routing Protocol: In [29], the SDN-enabled SPIN routing protocol is proposed for SDN-based WSNs. This SDN-enabled SPIN routing protocol introduces SDN-enabled sensor nodes and divides into normal and controller nodes. The SDN-enabled reconfigurations work behind the scene of the SPIN routing protocol. This proposed model claims to achieve better energy efficiency and also enhance network security by strengthening the central control over WSNs. This protocol also lacks the envision of the central controller at BS as individual nodes contain limited networking resources. In above mentioned routing protocols, two of the major drawbacks are lack of application-awareness and distributed nature cluster-formulation. In order to achieve these two distinct features, we propose SDN-based Application-aware Distributed adaptive Flow Iterative Reconfiguring (SADFIR) routing protocol for IoT. In particular, the SADFIR improves the existing features and characteristics of SDN-based WSNs, which is summarized as a comparative view in Table 1. \begin{table}
\begin{tabular}{l l l l l l l} \hline \hline
**Management** & **Network** & **Application** & **Heterogeneity** & **Topology** & **Computational** & **Periodic** \\
**Architecture** & **Scalability** & **Awareness** & **Awareness** & **Discovery** & **Cost** & **Reconfiguration** \\ \hline SDN-WISE [1] & ✓ & ✓ & ✓ & ✓ & & ✓ \\ \hline SDCSN [7] & ✓ & & ✓ & & ✓ & \\ \hline Sensor & ✓ & & ✓ & & ✓ & \\ OpenFlow [13] & & & & & & \\ \hline Soft-WSN [21] & ✓ & & & & ✓ & \\ \hline TinySDN [22] & & ✓ & ✓ & ✓ & & ✓ \\ \hline TinySDM [30] & & & ✓ & & ✓ & ✓ \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Summarized review of SDN-based sensor networks.