Saving Energy on WiFi with Required IPsec

The move to a pervasive computing environment, with the increasing use of laptops, netbooks, smartphones and tablets, means that we are more reliant on wireless networking and batteries for our daily computational needs. Specifically, this includes applications which have sensitive data that must be securely communicated over VPNs. However, the use of VPNs and mobile, wireless computing creates conflicting needs: VPNs traditionally assume a stable network connection, which is then secured; in contrast, wireless computing assumes a transitory network connection due to mobility or energy-saving protocols. In this work we study the ability to use traditional VPN protocols, specifically IPsec, in mobile environments while permitting for energy savings. Energy savings come from power-cycling the wireless radio when it is not in use. More specifically, we develop a mathematical model for determining potential power savings on mobile devices when power-cycling the radio in IPsec use settings. Next, we perform performance measurements on IPsec session resumption protocols IKEv2 [1], MOBIKE [2], and IPsec Gateway Failover (IGF) [3] to provide data for our model. We apply the model to over 3000 wireless sessions, and determine the optimal power savings that could be achieved by power-cycling the radio while maintaining an IPsec connection. We show that there is a highpotential for energy savings in the best case. Finally, we develop an efficient and simple real-world online scheduling algorithm that achieves near optimal results for a majority of users.