<p>A VPN device (2) requests registration for the VPN device (2) from a VPN device (4) by communicating with the VPN device (4) using only the IP address of the VPN device (2). The VPN device (4) registers the IP address and the base ID of the VPN device (2). The VPN device (4) provides to the VPN device (2) a settings table in which the IP address and base ID of each VPN device is registered. A VPN device (6) registers the IP address and base ID of the VPN device (2) provided by the VPN device (4).</p>
