I have a site-to-site VPN connection between a Windows Server 2008 R2 server and a SonicWALL firewall device (ESP: 3DES/HMAC SHA1 (IKE)).
Although on the firewall, I have the "Enable Keep Alive" setting enabled, periodically it seems like the tunnel comes down.
The remote server has a shared path that needs to be available at all times for backing files up. This share has been assigned a drive letter on one of the local servers that can communicate with the remote server when the tunnel is up.
When up, the folder is available just fine, but it seems that after a while, the connectivity is lost. Windows will time-out (prompt that the shared folder network location is not available) before the tunnel is back up.
If I console into the remote server, ping the local server, the tunnel wakes up after a failed ping attempt or two. At that point, the local server can access that shared path again.
Short of creating a "ping" scheduled task, what can I do to ensure this tunnel is always up?