VPN is a private network established within a public network infrastructure. Through VPN, offices or individuals can access safely the network of their organization. Configuring a VPN, data can be distributed in the network equally as if they were connected to the cable in a point-to-point LAN.
VPN security is achieved through tunneling technique, where packages are encrypted, and the encrypted payload is encapsulated within the packet.
Benefit of VPN is to allow an organization to have secure connection between offices or geographically separated users using existing connections (ADSL, ISDN, cable). Protocols that support these services are PPTP, IPsec, L2F, L2TP.
ABCom IP backbone infrastructure has given priority to IP VPN IPsec protocol in order to converge to a high priority service.
There are several reasons for the construction of VPN, but the most important is virtual communication between members of an organization that are geographically separated. Communication is "invisible" from the outside and at the same time has the advantage because it uses existing infrastructure. IP VPN service allows our customers (governmental organizations and non-governmental organizations, banks and various institutions) to log in the network of the company and to set a quick and secure connection. Another reason is that the communication is very economical, a collection of virtual networks implemented on a single physical network being free to operate.
Before you know the time and resources it takes to configure and maintain VPN, you should know why you need and how to use it. If you want use it only for remote access to mail, then the VPN is not practical. VPN is suitable for business applications such as those explained below.
Internal network between offices
VPN can be used wherever the need for a safe connection point-to-point between offices that are far away. For example, in a large hospital the main system is in the administration office, and laboratories are located elsewhere. Instead of seting up connections through the lines, you can create a low-cost VPN and data can be exchanged safely over phone lines. A VPN device (switch, router, or server) is placed between the network and main network department.
A company may have a small branch or employees working remote and that their job depends on the central office, or may have clients who want to have access to secure data.