Huawei v200r001 Configuration of L2TP, Brief Introduction to L2TP Protocol, Overview of Vpdn

User Manual - Configuration Guide (Volume 3)	Chapter 2
Versatile Routing Platform	Configuration of L2TP

Chapter 2 Configuration of L2TP

2.1 Brief Introduction to L2TP Protocol

2.1.1Overview of VPDN

I.Brief induction to VPDN

In VPDN, VPN is fulfilled with dial-up and access services (ISDN PSTN) of public network, which provides access service for enterprises, mini ISP and mobile offices. As telecom carriers and large ISPs have a lot of access equipment, facilities and management experiences, other enterprises can make full use of their existing equipment and facilities instead their own investment on access equipment, so that their services can be more specialized and systematic.

VPDN adopts private network encryption and communication protocol, so enterprises can establish safe VPN on public networks. Enterprise personnel on business leave can connect with enterprise's remote internal network via virtual encryption channel, while other users on public networks can not access the Intranet resources via such virtual channel.

VPDN is often used by the following users:

z Those users whose branches are geographically distributed, with many mobile personnel, e.g. enterprise users and tele-education users.

z Those users whose are geographically distributed have to rely on toll calls or even international toll calls.

z Those who have specific requirements for line security and availability.

II. Operation principle of VPDN

The networking diagram of typical VPDN application is shown in the following figure.

Remote users

Internet backbone network

PCNAS

PSTN/ISDN

NAS

LNS

L2TP

Remote users

Internal server

Figure VPN-2-1Networking diagram of typical VPDN application

VDPN is composed of NAS, equipment at user side and management tool.

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