# Internet of Nano-Things, Things and Everything: Future Growth Trends
## 6 Challenges and Impediments to IoT
### Software Defined Networks (SDN)  
SDN offers the flexibility and adaptability needed for the successful universal deployment of IoT devices. The integration of SDN with IoT is thus considered to be another major and urgent challenge. Cost constraints and the time to market will also influence the operability and design of IoT devices. The challenges presented demand the adoption of universally agreed upon standards for the IoT devices to operate successfully in the global market.  
The fluid malleability of Software Defined Networking (SDN) is seen as being a positive disruptive force in computer networking. Benefits include programming network switching elements (forwarders) to program packet routing to any port based on any specified packet parameter. This is of special concern that will benefit IoT devices to communicate with each other over a heterogeneous network. Thus, amalgamating SDN with IoT is one strong way forward. However, this poses other challenges that must be circumvented, especially in operational validation of the hybrid-combined network against the current disparate networking solutions.  
The adoption of SDN is accelerating because of its huge potential in hardware cost savings. SDN through its very nature of extreme software configurability allows generic network components to take on any function, such as a switch or router. SDN can be seen as the stem cell programming of computer networking. The SDN model also differentiates and isolates the control and signaling plane from the data planes. The intermediate networking elements of SDN have also been simplified to be forwarders of packets. A general control protocol is used with forwarding rules to achieve this. A central processing unit or the brain of the SDN also acquires the stable topology of the SDN network. This then allows optimized routing decisions to be made along with optimized and parsed forwarding rules. Adopting the characteristics of the SDN can be utilized to deal with IoT operating in a heterogeneous network. Thus, the IoT network can be scaled and a new high-level control solution can be created that interfaces seamlessly with the SDN controllers, as shown in Figure 10[74].  
As shown in Figure 10, there exist two distinct planes, the control plane and the data plane. Two IoT objects can interact with each other through the SDN-enabled network using their respective internal IoT agents. Contextual information is conveyed to the IoT Controller, which then passes that to the underlying SDN Controller. The IoT Controller, though shown as a monolithic block, may in fact be composed of several internal modular blocks. This flexibility enables new functionalities to be added to the IoT object without affecting its final relation with the SDN Controller.  
The major current impediment for a universal model as shown in Figure 10 is the lack of a stable IoT architecture. The other major factors delaying the creation of the universal model is that there is no standardization for IoT content awareness provisioning and Quality of Support (QoS).  
Figure 10: IoT and SDN Conceptual Integration Overview. Adapted from [74].