Support for Virtual Private Networks (VPNs) 29
Support for Virtual
Private Networks
(VPNs)
Through its support of the Point-to-Point Tunnel Protocol (PPTP), the Dual 56K
LAN Modem allows users on any workstation attached to the LAN Modem to
communicate with a remote private network over the Internet using a Virtual
Private Network (VPN) tunnel, provided the necessary client software is installed
on the user’s workstation.
Although the LAN Modem allows for the transparent passage of VPN tunnel data
from a computer on its LAN side to its WAN side, the LAN Modem cannot itself
initiate or terminate a tunnel. In other words, the LAN Modem does not encrypt or
encapsulate data on the outgoing side of the VPN connection, nor does it act as a
tunnel terminator to unpack tunnel packets on the incoming side.
VPN tunnels are a private, secure means by which content-sensitive data that uses
any routing protocol can be transported over the public, IP-routable-only Internet.
Because a VPN tunnel is established through a local call to an Internet Service
Provider, a user connecting to a remote Private Network through a VPN tunnel can
eliminate long distance charges that might otherwise be incurred from dialing
directly to the remote private network.
Figure 14 shows a VPN tunnel connection to a remote private network using a
single, locally-dialed ISP call.
Figure 14 VPN Tunnel Connection to a Remote Private Network via an ISP
To create a VPN tunnel from a workstation attached to the Dual 56K LAN Modem,
no special configuration of the LAN Modem is required. The client workstation
must, however, have the appropriate software, and a tunnel server must be set up
at the remote private network.
Basic instructions for setting up and initiating a VPN tunnel from a client
workstation are provided in Appendix C, “Creating a Virtual Private Network
(VPN) Tunnel.”
Public telephone
network
Dual 56K LAN Modem
Workstation
with PPTP
client software
PPTP Tunnel
server
VPN tunnel
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OfficeConnect Dual 56k LAN Modem
LAN StatusMODEM 2MODEM 1
Internet
