Network Virtualization Using VPN for Stable Communication with Offshore Cloud.

It has become common to access cloud computers in other countries via the Internet. However, in some countries, many international communication channels are suddenly shut down by governmental bodies. This causes significant degradation of the Quality of Service (QoS) for accessing cloud computers, Web conferences, and so on. To cope with this, we propose a network virtualization method for intelligent routers to detect the restriction of international communication and form VPN bypass. The routers placed at user's offices bypass/switch routes from the internet to VPN contracted by each enterprise or company to ensure QoS and only during shutdown and the like not to be regulated by governmental bodies. More concretely, a method for applying asymmetric criteria to decide whether to bypass is proposed for robust Internet operation to keep connections with cloud servers. Differential values of network latency are used for detecting the start of intentional network barriers, and absolute threshold values to determine both their start and end. This method is verified by a network simulator as well as latency on real regulation. Validation has been done by more than 50 offices' successful real usage.