# Software Defined Networking for Improved Wireless Sensor Network Management: A Survey
## 5 Management of WSNs Based on SDN
### Network Configuration Management  
Network configuration management is a functional area that will allow the sensor network to meet its required specification. In an SDN-based WSN architecture, the first challenge with meeting the requirements has to do with SDN support for the WSN architecture [28]. SDN was designed for conventional networks which are different from WSNs and therefore it is necessary to configure the network to enable SDN support efficiently. This is particularly important in harnessing existing network management protocols and architectures which can provide the SDN-based WSN with a proper network management model [29]. Several proposals have been made towards configuring and extending SDN functionality for wireless sensor applications. Sensor OpenFlow (SOF) [20; 21] is one such proposal which serves as a standard communication protocol between the data plane and control plane and is a core component of WSNs based on SDN. The idea is based on the data plane that is composed of sensors performing flow-based packet forwarding and the control plane consisting of a controller handling all the network intelligence at a central place (Centralized Control). This allows the data plane to be fully programmable by customizing the flow table of each sensor. The challenge with this concept is that it is built on the fundamental OpenFlow assumption that the underlying network is made of Ethanet switches and IP routers which are wired protocols useful in cellular and enterprise backbones and data centers; and not so much in WSNs. Moreover, using the centralized controller would raise questions on the management of security in an event of attacks directed towards the controller [14]. Thus, adequate network security management has to be in place. Software Defined Wireless Network (SDWN) is yet another solution that has been prototyped to extend SDN functionality in wireless and mobile communications specifically providing support for SDN in Low Rate Wireless Personal Area Networks (LR-WPANs) [60]. SDWN uses energy management techniques such as duty cycling, in-network data aggregation and cross layer optimization to reduce energy usage. However, adapting the SDWN architecture to integrate and configure SDN for WSNs to enable efficient energy use needs further investigation as the SDWN requires messages to be passed between control and data layers which may strain the already resource constrained WSN. [PERSON] et al. [78] have proposed SDN-WISE (SDN-Wireless SEnsor network), a technique which makes sensor nodes programmable as finite state machines so as to enable them to run applications that cannot be supported by stateless solutions. It provides an API which allows developers to program the SDN controller in a language of their choice enabling simplicity and flexibility in the management of network programming. This is especially useful when managing a large-scale and long range wireless sensor network. Configuration of SDN-based WSNs should allow the SDN protocols which are address-centric to address the inherently data-centric WSN. A solution [21] to this would be integrating the use of IP stacks such as uIP, uIPv6 [79; 80] based on Contiki OS [81], Berkley Low power IP (BLIP) based on Tiny OS [82; 83] for low power networks. As a result of this integration IPv6 based low-power wireless Personal Area Networks (6 LowPAN) have been realised. Management architectures based on the 6 LowPAN protocol have thus been proposed including the LowPAN Network Management Protocol (LNMP) [84], 6 LowPAN-SNMP [85] which is an extension of the existing SNMP [31] protocol and a further network management architecture based on SNMP for 6 LowPANs proposed by [PERSON] et al. [86]. These management architectures although used for various wireless networks provide a model for developing a proper network management architecture for the WSNs based on SDN [29].