3Com Dual 56K manual Support for Virtual, Private Networks, VPNs

Support for Virtual Private Networks (VPNs) 29

Support for Virtual	Through its support of the Point-to-Point Tunnel Protocol (PPTP), the Dual 56K
Private Networks	LAN Modem allows users on any workstation attached to the LAN Modem to
(VPNs)	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.

	VPN tunnel
Workstation
with PPTP
client software	Public telephone

Internet

network

Dual 56K LAN Modem PPTP Tunnel

server

Corporate office

LAN

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.”