Network virtualization by differentially switched VPN for stable business communication with offshore computers

Accessing offshore cloud or remote computers via the Internet has become popular. However, in some countries, governmental agencies or organizations may suddenly block international communication links. Temporary blocks or more permanent barriers as China’s Golden Shield (GS) are known to introduce significant network latency or Quality of Service (QoS) degradation that may hinder offshore business. To avoid this, we propose a network virtualization method and tool based on recognizing step-wise increases of Round Trip Time (RTT) that are caused by intentionally blocking international communication links. Our method predicts and avoids intentional blocks or restriction as follows: (1) the onset of the restriction is predicted or recognized in the early stage, using differential calculus of RTT, (2) immediate switching to Virtual Private Network (VPN) bypass is automatically performed before serious increase in network latency is experienced by users. (3) Asymmetrically, non-differential threshold value and elapsed time are used to determine the end of restriction and switch back to the open (ordinary or public) Internet. Our method is validated by quantitative analysis on latency data corresponding to real GS blocks. Furthermore, 2–3 years’ successful usage of our tool in more than fifty offices confirms our method’s stable and dependable communication as well as its reasonable cost.