3Com OfficeConnect Remote 812 manual On the Remote Private Network Server Side

6-6CHAPTER 6: MANUAL SETUP

VPN Tunneling Overview

Before You Begin

Initiating a VPN Tunnel

A VPN tunnel is a private virtual circuit that uses public wires to connect two nodes. For example, it is common practice to create VPNs that use the Internet as the public medium over which private information is sent and received.

Tunnelling is a technology that enables one network to send its data via another network’s connections. Tunnelling works by encapsulating a network protocol within packets carried by the second network. Using this technology, you can transport data over the Internet between administrative domains that use a protocol the Internet does not support (specifically, this is done by embedding private data inside TCP/IP packets).

On the 812 ADSL Router, tunnelling is accomplished by encapsulating protocol A within protocol B. In effect, protocol A treats protocol B as if B were the Data Link layer (the OSI layer concerned with physically passing data from one node to another).

Before you can initiate a VPN tunnel to a remote private network, you (or a network administrator) must do all of the following:

On the Remote Private Network (“Server”) Side:

￿		Set up a PPTP tunnel server (also called a tunnel “terminator”) on the
		remote private network.
		Examples of a PPTP tunnel server are a Windows NT server (Windows 2000,
		version 4.0 or later, with Service Pack 3 or greater and RAS installed) or
		3Com’s Total Control Hub.
		Install any networking protocols required for the private network on the
		PPTP tunnel server (such as IP, IPX, and NetBeui).
	On the 812 ADSL Router (“Client”) Side:
	￿	Configure the OCR 812 for a VPN.
	￿Install any networking protocols required for the private network on each
		workstation that will establish a VPN tunnel.

￿Any￿user on a local private LAN can send traffic to a user on a remote private LAN. When a user on the local LAN sends a packet to a user on the remote LAN, the OCR 812 detects this attempt and automatically places a call to the remote LAN. Once the call is connected, a VPN tunnel is automatically initiated (created and enabled) between the OCR 812 and the tunnel server at the remote private network.

A VPN tunnel gives you access to a remote private LAN without requiring you to implement a direct physical connection. In addition, once your ISP connection is established, other users on the same local and remote LANs can use the existing VPN tunnel.

The default setting for VPN tunnels is disabled.