Spatio-Temporal Multi-Stage OpenFlow Switch Model for Software Defined Cellular Networks

The tremendous increase on mobile data traffic has stressed conventional cellular networks recently. In order to handle this rapid increase, Software Defined Networking (SDN) is proposed as one of the novel approach that makes it easier to orchestrate physical devices in Data Plane with its centralized control fashion. On one hand, SDN provides scalability and flexibility on network management with dummy OpenFlow(OF) switches and its nature of centralized authority; on the other hand, these properties cause spatial and temporal complexity in the Data Plane. Spatial complexity, described as Memory Usage in an OF switch, should be minimized by removing redundancy on OF switch flow table pipeline. Temporal complexity, defined as Flow Forwarding Delay, should also be reduced by lowering number of comparison in OF switch pipeline to enhance Quality of Service (QoS) of a flow. Therefore, in this paper, a novel Multi-Stage OF (MsOF) Switch model is proposed and examined considering Queuing Theory in the light of spatial complexity and temporal complexity parameters. According to performance evaluation results, specially in urban areas, MsOF has much less spatial and temporal complexity considering conventional OF switch model as the number of input ports in an OF switch (N) increases. MsOF gains much memory space by deploying more tables with less memories, total of (n · k). Furthermore, with such a Multi-Stage deployment of flow tables, MsOF provides approximately 7 times less flow forwarding delay, compared with a conventional OF Switch for a network load more than %60.