42 CONFIGURING VPN
This chapter covers the following topics:
■VPN Overview
■Basic Networking Applications of VPN
■Classification of IP VPN
VPN Overview VPN establishes private networks on public networks by creating a “virtual”, or
logical network from resources of the existing network. Carriers can make use of
their spare network resources to provide VPN service and profit from the network
resources to the maximum extent. In addition:
■VPNs are used by enterprises or user groups to securely access remote
networks. From the perspective of VPN users, it makes no difference whether
they use VPN service or traditional private networks. Being a private network,
VPN keeps its resources independent from those of the carrying networkand
the resources of a VPN cannot be used by other VPNs on the same carrying
network or by network users who do not belong to the VPN. The VPN is safe
enough to make sure that the internal information within a VPN is free from
being invaded by external users.
■VPN technology is more complicated than the mechanisms of various ordinary
point-to-point applications. Network interconnection between the users of
private networks is required for VPN service, including the creation of VPN
internal network topology, route calculation, adding and deleting of members.
The advantages of VPN include:
■The security of data transportation can be ensured. With VPN, reliable and safe
connections can be established between remote users, branches of companies
and commercial partners, and between suppliers and headquarters of
companies. The advantage is especially significant in the integration of
E-commerce or financial networks with the communication networks.
■Communicating information over the public networks decreases the cost for
enterprises in connecting their remote branches, staff on business trips, and
the business partners. It also improves the utility ratio of network resources and
thereby increases the profits of Internet Service Providers (ISPs).
■VPN users can be added and deleted by configuring parameters without
changing hardware, which makes VPN applications highly flexible.
■With VPN, VPN users can make mobile access at any time and any place,
meeting the increasing mobile service requirements.