Billion BEC MX-1000 User Manual page 120

Example: Configuring L2TP LAN-to-LAN VPN Connection
The branch office establishes a L2TP VPN tunnel with head office to connect two private networks
over the Internet. The routers are installed in the head office and branch office accordingly.
Note:
Both office LAN networks must be in different subnets with the LAN-LAN application.