About Virtual Private Networks

A Virtual Private Network (VPN) provides a secure connection between two or more computers or protected networks over the public Internet. It provides authentication to ensure that the information is going to and from the correct parties. It also offers security to protect the data from viewing or tampering en route.

A VPN is created by establishing a secure tunnel through the Internet. This tunnel is a virtual point-to-point connection through the use of dedicated connections, virtual tunneling protocols, or traffic encryption. It is flexible in that you can change it at any time to add more nodes, change the nodes, or remove them altogether. VPN is less costly, because it uses the existing Internet infrastructure.

VPNs can support either remote access—connecting a user’s computer to a corporate network—or site to site, which is connecting two networks. A VPN can also be used to interconnect two similar networks over a dissimilar middle network: for example, two IPv6 networks connecting over an IPv4 network.

VPN systems might be classified by:

• Protocols used to tunnel the traffic
• Tunnel's termination point location, for example, on the customer edge or network provider edge
• Type of topology of connections, such as site to site or network to network
• Levels of security provided
• OSI layer they present to the connecting network, such as Layer 2 circuits or Layer 3 network connectivity
• Number of simultaneous connections