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̈ Chapter 14: Virtual Private Networks—VPN LANCOM Reference Manual LCOS 3.50
291
Virtual Private Networks—
VPN
14 Virtual Private Networks—VPN
14.1 What does VPN offer?
A VPN (Virtual Private Network can be used to set up cost-effective, public IP
networks, for example via the Internet.
While this may sound unspectacular at first, in practice it has profound effects.
To illustrate this, let's first look at a typical corporate network without VPN
technology. In the second step, we will see how this network can be optimized
by the deployment of VPN.
Conventional network infrastructure
First, let's have a look at a typical network structure that can be found in this
form or similar forms in many companies:
The corporate network is based on the internal network (LAN) in the
headquarters. This LAN is connected to the outside world in three ways:
ᕡ A subsidiary is connected to the LAN, typically using a leased line.
ᕢ PCs dial into the central network via modem or ISDN connections (Remote
Access Service – RAS).
Headquarters
Computers
using remote
access, e.g.
home working
Internet
ᕡ
ᕢ
ᕣ
LAN
LAN
Branch office
ISDN ISDN
ᕢ