VPN (Virtual Private Network)

A traditional private network consists of leased lines connecting multiple sites together. An example would be two offices connected by a point-to-point T-1 line.

Connecting multiple sites together over the Internet is usually less expensive than leasing dedicated circuits. One risk in using the Internet as a transport medium is the risk of data interception by unauthorized parties. When data is moved across the Internet, it should be considered public knowledge.

A VPN (Virtual Private Network) solves that problem. A VPN is an encrypted tunnel between two endpoints. A VPN is a private network that works on a public network, like the Internet, to connect distant sites or users together. In place of installing a dedicated connection such as leased line, a VPN uses "virtual" connections routed via the Internet from the organization’s private network to the distant location. Virtual private networks assist distant team members to operate together, much like desktop sharing.

VPN tunnels are created using a tunneling protocol such as L2TP and secured using a protocol such as IPsec.

L2TP is described in RFC 2661: Layer Two Tunneling Protocol "L2TP". IPsec is described in RFC 3193: Securing L2TP using IPsec.

Advantages of VPN

­An ideal VPN can be significantly advantageous to an organization. It can,

• broaden geographic connectivity
• implement advance security measure
• lessen operational costs
• lessen travel time and transportation expenses for distant members
• enhance productivity
• shorten network topology
• offer global networking prospects
• offer compatibility with broadband networking
• revert with quicker Return On Investment (ROI)