Billion BiPAC 8500/8520 User Manual page 135

Example: Configuring L2TP LAN-to-LAN VPN Connection
The branch office establishes a L2TP VPN tunnel with the head office to connect two private
networks over the Internet. The routers are installed in the head office and branch office
respectively.
Both office LAN networks MUST be in different subnet with LAN to LAN
application.Functions of Pre-shared Key, VPN Connection Type and
Attention
Security Algorithm MUST BE identically set up at both ends.
Attention
Chapter 4: Configuration
Billion BiPAC 8500/8501/8520/8521 SHDSL (VPN) Firewall Bridge/ Router
131