In this paper we study a data-supported caching policy design for wireless D2D caching networks, which is based on a dataset collected from a campus Wi-Fi network. After a well-designed preprocessing for the dataset, for the first time, we conduct a real dataset based performance evaluation for the caching policies designed based on the homogeneous Poisson Point Process (PPP) model and a clustered PPP model. We proceed to propose a novel approach for the design of the D2D caching policy. It directly models the number of D2D neighbours, instead of characterizing the locations of users as the PPP models. We show that the number of D2D neighbours can be well modeled by a discrete Gamma distribution. Given the model, we develop an iterative algorithm to optimize the D2D caching policy, and also provide a method to optimize the cache update time in order to balance the caching gain and overhead. Simulation results based on the dataset show that the proposed caching policy can achieve good performance with low cost of cache updating.

The current IPsec gateway integrates many functions of IPsec operation, tunnel management and forwarding decision, which makes the IPsec gateway complicated in maintenance and deployment. The problem of maintaining such devices prevents IPsec VPN from applying widely. The emergence of SDN provides an innovative way to decouple the control plane and data plane. In this paper, a Software-Defined IPsec Gateway (SDIG) is proposed to achieve net2net IPsec VPN. Different from the traditional IPsec gateway, the SDIG device serves as a data plane equipment that just concentrates on exchanging IKE packets and encrypting/decrypting IP packets. A global view of SDIG devices can be constructed in the SDN controller by collecting the status of all devices. Therefore the controller can manage and configure SDIG devices centrally, and simplify deployment complexity. Outbound IP packets for the SDIG device can be viewed as a trigger to control the establishment of IPsec tunnels. The SDIG device and the controller exchange information through a customized southbound protocol. The prototype system of SDIG is implemented, and the preliminary experimental results show that the method is feasible and effective.