ZyXEL Communications Parental Control Gateway HS100/HS100W - Manual (Page 319)

HomeSafe User’s Guide
PPTP C-1
Appendix C
PPTP
What is PPTP?
PPTP (Point-to-Point Tunneling Protocol) is a Microsoft proprietary protocol (RFC 2637 for
PPTP is informational only) to tunnel PPP frames.
How can we transport PPP frames from a PC to a broadband
modem over Ethernet?
A solution is to build PPTP into the ANT (ADSL Network Termination) where PPTP is used
only over the short haul between the PC and the modem over Ethernet. For the rest of the
connection, the PPP frames are transported with PPP over AAL5 (RFC 2364). The PPP
connection, however, is still between the PC and the ISP. The various connections in this setup
are depicted in the following diagram. The drawback of this solution is that it requires one
separate ATM VC per destination.
Diagram C-1 Transport PPP frames over Ethernet
PPTP and the HomeSafe
When the HomeSafeis deployed in such a setup, it appears as a PC to the ANT (ADSL Network
Termination).
In Windows VPN or PPTP Pass-Through feature, the PPTP tunneling is created from Windows
95, 98 and NT clients to an NT server in a remote location. The pass-through feature allows users
on the network to access a different remote server using the HomeSafe's Internet connection. In
NAT mode, the HomeSafeis able to pass the PPTP packets to the internal PPTP server (i.e. NT
server) behind the NAT. Users need to forward PPTP packets to port 1723 by configuring the
server in Menu 15.2 - Server Set Setup. In the case above as the PPTP connection is initialized
by the remote PPTP Client, the user must configure the PPTP clients. The HomeSafeinitializes
the PPTP connection hence, there is no need to configure the remote PPTP clients.