The introduction of IPsec into software-defined networking (SDN) can secure communication in an SDN southbound interface, i.e., communication between the controllers and the switches. However, due to the static configuration of IPsec cryptographic algorithms, the invocation of these algorithms cannot dynamically self-adapt to traffic fluctuations in SDN southbound communication. To address the contradiction between link security and communication performance incurred by IPsec encryption, an evaluation model to find a trade-off between communication performance and link security is presented in this paper. An invocation mechanism based on the Free-to-Add (FTA) method is also proposed to optimize the invocation mode of cryptographic algorithms in traditional IPsec. Based on the real-time network status and the impact of the IPsec encryption process on the network latency and throughput, a feedback-based scheduling scheme is designed to enable the IPsec algorithms in use to be flexibly replaced and synchronously switched, and two policies are applied to determinate the appropriate encryption algorithm(s). The validity and effectiveness of the FTA-based mechanism are verified and evaluated on an SDN/OpenFlow platform in which IPsec security gateways are deployed. The feedback-based scheduling scheme is evaluated in terms of packet processing latency, distribution of optional encryption intensity, and the hit rate of encryption intensity.

Currently, the development of multimedia communication has progressed so rapidly that the video program service has become a requirement for ordinary customers. The quality of experience (QoE) for the visual signal is of the fundamental importance for numerous image and video processing applications, where the goal of video quality assessment (VQA) is to automatically measure the quality of the visual signal in agreement with the human judgment of the video quality. Considering the codec effect to the video quality, in this paper an efficient non-reference (NR) VQA algorithm is proposed which estimates the video quality (VQ) only by utilizing the distorted video signal at the destination. The VQA feature vectors (FVs) which have high relationships with the subjective quality of the distorted video are investigated, and a hybrid NR VQA (HNRVQA) function is established by considering the multiple FVs. The simulation results, testing on the SDTV programming provided by VCEG Phase I, show that the proposed algorithm can represent the VQ accurately, and it can be used to replace the subjective VQA to measure the quality of the video signal automatically at the destinations. © 2011 KSII.