# Software Defined Networking for Improved Wireless Sensor Network Management: A Survey
## 3 Network Management Based on SDN
Between the application plane and the control plane are the northbound APIs and between the controller and the data plane exist the southbound APIs. The Southbound APIs facilitate for the flow of control traffic from the controller to the devices in the data plane. OpenFlow [20; 21; 58] is standard commonly used as a southbound interface [27] and most vendors are producing more OpenFlow capable network infrastructure. East-West APIs enable controllers that are in the same domain or neighbouring domains to communicate with each other [59]. It is important to mention here that SDN is not about improving the performance of the network but rather SDN has been seen to have the potential to simplify network management and allow for innovation through network programmability. Updates to network control and management are made as easy as installing new applications on a computer [60]. SDN changes the network administration problem into a programming problem increasing flexibility, other potential benefits of SDN in WSNs [14] include:  
1. Energy management: WSN nodes are energy constrained and thus need energy-efficient protocols to be employed in sensor networks. SDN can provide an energy efficient way for network management of WSNs. This is possible as having a logically centralized control plane maintains a complete view of the entire WSN and thus can reduce the power consumed by nodes in maintaining that view locally. Control plane functions can manage all the routing protocols saving nodes from following application specific protocols which might drain energy depending on traffic. Alternative energy management techniques can also be employed at the control plane. 2. Configuration management: The complexity of network management can be simplified with due to the increased flexibility of SDN, new routing protocols can be employed easily without reconfiguring the nodes and also it reduces the need for compiling different versions for the same network applications for different sensor nodes. Thus, if a new management and control method becomes available, it can easily be deployed resulting in efficiency of operation. Network management with different vendor specific network hardware can be challenging [27]. Network operators need to adjust to low-level vendor specific hardware configurations to implement complex high-level network management policies. Network management schemes such as those discussed in the previous section encounter difficulties in changing the policies embedded in the underlying network infrastructure. The direct result is the existence of application specific networks with few possibilities for improvement and innovation. New possibilities in management of a network and configuration can be introduced by SDN. SDN helps solve some of the problems of network management by enabling easy and frequent changes to the network function and state,  
Figure 1: SDN overall architecture. allowing configuration of the network in high-level languages and providing visibility and control over the entire network making it easier to troubleshoot problems in the network. In traditional wired/wireless networks, network operators have to implement and configure networks using a set of low-level device commands in the command line interface [27]. This is especially a problem with constantly varying network conditions. Operators have to manually adjust configurations frequently to meet these changes leaving room for misconfiguration and mistakes in implementing changes [61]. With SDN it is much easier to integrate new protocols and ideas into the network through the use of a centralized controller. SDN introduces a global approach to management of network configuration rather than local management which would require configuration for each of the network devices to implement changes or integrate new services. Several work has been researched and proposed on the potential benefits of implementing SDN in both wired and wireless networks [14; 21; 24; 28; 62].