There's a patch out there that has both sides send "alive" packets to each other to verify the connection is still up on both ends. If it fails, it will drop the connection, and if the connection is set to auto=start it will attempt to reconnect. I've noticed when I've got astaro configured to act as a "server" (i.e. only accepts in comming connections), and I have it restart the vpn service, the connections are dropped, but the other sides are not made aware of this, requiring them to re-init the connection.
