Intro
Often IPv6 is used via dialup line and/or tunnel brookers. Sometimes the dialup fails, the tunnel is unavailable or not connected properly. With monitoring remote systems, it makes sense not only to check if the system is up and running, but also, in case of an error, to check if the connection from the monitoring system to the monitored system is valid.
To accomplish this, you can se a “parent” to the monitored system, and use a “gateway” as parent. The gateway is not checked directly, that means it is out of interest if the gateway is up and running (ping-able). Instead, the proper function of the gateway is checked. And this function is: “connect me to the internet”. In case this function is given, you can tell that a remote host which is not up has a problem, and not your internet/IPv6 connection.