Wireless networks are less stable and require features to maintain the persistence of VPN tunnels so remote users can count on stable VPN tunnels regardless. In VPN Mobile, both failures of the remote gateway and the current wireless network used can be detected to make sure the tunnel is always on when physically possible.

Failure of the remote gateway is detected using DPD mechanisms (Dead Peer Detection) because the wireless network can be available while the remote gateway has restarted its WAN interfaces. Once a failure has been detected, VPN Mobile attempts several times (i.e. configurable) to restart the tunnel on the same network .

The selected wireless network (3G, GPRS or WiFi) is constantly monitored to detect lost. In case of unavailability of the wireless network, VPN Mobile attempts several times to restart the tunnel on the same network as the wireless disconnection might have been brief. If the wireless network is still not available after several attempts, the following windows pops up to inform the user so that he can use another wireless network depending his location:

If there is no more WiFi network available or if WiFi just failed because the user comes out of his office building, a GSM/GPRS, EDGE or 3G connection is automatically opened, if already configured/enabled, and VPN tunnel is up immediately as the VPN Mobile has detected the network change instantaneously. Corporate network is still available without user noticing network change.

As soon as the GSM/GPRS, EDGE or 3G connection is lost, and the WiFi connection is enabled, the VPN Mobile will try to reopen VPN tunnel immediatly without user noticing. WiFi network might not be available right away therefore several attempts are made till the VPN tunnel opens again.

In addition, auto open tunnel on traffic feature allows to open VPN tunnel to the right gateway by detecting traffic to that destination. In case the wireless connections have been disabled for some times to save battery and enabled again, VPN tunnel will open as soon as the user clik on email synch or tries to access an URL in the browser.

Tunnel Persistence makes easier VPN software for mobile users regardless of standards and technologies used by the wireless providers or the visited wireless networks.