3com 812 Manual De Usuario
6-6
C
HAPTER
6: M
ANUAL
S
ETUP
VPN Tunneling Overview
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.
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).
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).
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 Begin
Before you can initiate a VPN tunnel to a remote private network, you (or a
network administrator) must do all of the following:
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.
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.
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).
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.
workstation that will establish a VPN tunnel.
Initiating 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.
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.
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.