Subnet Addressing in Software Defined Wireless Sensor Networks

Software defined networking provides manageability and scalability to networks by decoupling network control and forwarding functions into separate layers. Though the concept is typically a subject for wired networks, recent research activities have also considered software defined networking in the context of wireless networking and especially in wireless sensor networking. Software defined networking in that context is, however, a very challenging task due to limited resources of the sensors. In particular, the number of entries in the flow table and the control message overhead is a limiting factor. This paper introduces a new approach to efficiently manage a software defined wireless sensor networks by means of a hierarchical addressing scheme. It is based on a tree of address masks which are used to split the network into subnets. Each subnet has a range of host addresses and a subnet head which acts as a gateway to its children. With that hierarchical structure, nodes need only to recognize the subnet where a packet is destined to and forward that packet to the subnet head. We evaluated the proposed approach using the Cooja simulation environment of Contiki. Compared to the state of the art our scheme reduces the amount of control messages, the size of path packets, the number of rules needed to be stored in the flow table and hence the processing time for these rules.