VPN technology Detailed (i)

VPN technology Detailed (i)
Lu Xiaopo
Introduction
A virtual private network enables the connection of components and resources across different networks. Virtual private networks can use the Internet or other public Internet infrastructure to create tunnels for users and provide the same security and functionality guarantees as private networks. (Figure 1)
A virtual private network allows a remote communication party, salesperson, or Enterprise branch office to connect to the enterprise server located on the corporate LAN side in a secure manner using the routing infrastructure of public Internet, such as the Internet. The virtual private network is transparent to the client, and the user seems to use a dedicated line to establish a point-to-point connection between the customer computer and the enterprise server to transmit data.
Virtual Private Network technology also enables enterprises to connect with branch offices or other companies through the Internet and other public networks for secure communication. This VPN connection across the Internet is logically equivalent to a connection between two places using a wide area network.
Although VPN communication is based on the public Internet, users feel like they are using a private network to communicate, so they get the name of a virtual private network.
Using VPN technology can solve the problem that the employees need to access the central resources and the enterprises must communicate with each other in a timely and effective way, when the long-distance traffic is increasing and the enterprise's global operation is widely distributed.
If you want employees to be able to connect with the enterprise computing resources wherever they are, the enterprise must adopt a highly reliable and scalable remote access solution. In general, enterprises have the following choices:
1. The Management Information System (MIS) department drives the plan. Establish an internal MIS department that specializes in purchasing, installing and maintaining enterprise modem pools and dedicated network infrastructure.
2. The value-added network (VAN) programme. Companies hire an external company to purchase, install and maintain modem pools and telecommunications network infrastructure.
From the aspects of cost, reliability, management and ease of connection, neither of these schemes can satisfy the enterprise's requirement of network security or extensibility to the greatest extent. Therefore, it is very important to choose a cheap solution based on internet technology to replace the investment that the enterprise spends on the modem pool and the dedicated network infrastructure.
Basic uses of virtual private networks
Remote user access over the Internet
Virtual private Networks support remote access to enterprise resources via the public Internet in a secure manner.
Unlike a network access server (NAS) that uses a dedicated line to dial long-distance or (1-800) telephone connections to an enterprise, a virtual private network user first dials the NAS of the local ISP, The VPN software then leverages the connection established with the local ISP to create a virtual private network across the Internet or other public networks between dial-up users and the Enterprise VPN server.
Network interconnection via the Internet
You can use VPN to connect to a remote local area network in the following two ways.
1. Use a dedicated line to connect branch offices and enterprise LANs.
Without the use of expensive long-distance dedicated circuits, branch offices and enterprise-side routers can connect to the Internet through local ISPs using their own local dedicated lines. The VPN software creates a virtual private network between the branch office and the enterprise router using a connection established with the local ISP and an Internet network.