Deploying a Fast Detection and Eviction Mechanism of Invalid Connection-Oriented Flow-Entries in SDNs: A Scalability Approach

As a new paradigm of network architecture, Software Defined Networking (SDN) has been used in a large number of scenarios because it realizes flexible and efficient fine-grained flow control of the network, and promotes the evolution of the network to a programmable and scalable direction. However, the transition of the traditional networking model to SDN architectures poses scalability issues due to the limitation of the flow-table in size. Facing the traffic explosion on future networks with resource-constrained architectures, the storage space of the flow-table is not enough to bear so many flow-entries so that it not only causes performance degradation in data delivery but also results in scalability and cost-efficiency issues. To address this issue, in this article, we propose a solution to expedited evict the invalid flow-entries by detecting the disconnect messages of connection-oriented protocols such as Transmission Control Protocol (TCP) and Stream Control Transmission Protocol (SCTP) based on SDN controller and OpenFlow or programming protocol-independent packet processors (P4) switches. The behavior of detection is achieved by adding a specific SDN ruleset within the transport-layer in between the controller and switches. Different from the original timeout solutions, our scheme can delete invalid flow-entries in time according to the transmission layer disconnection instead of relying on the original timeout mechanism. Through a series of simulation results. we also demonstrate the superiority of our proposed solution in reducing the flow-entries occupancy and control overhead on controller, and improving the table-miss rate.