A virtual private network (VPN) is a private communications network often used within a company, or by several different companies or organizations, to communicate confidentially over a publicly accessible network. VPN message traffic can be carried over a public networking infrastructure (e.g. the Internet) on top of standard protocols, or over a service provider's private network with a defined Service Level Agreement (SLA) between the VPN customer and the VPN service provider.
A well-designed VPN can provide great benefits for an organization. It can:
Extend geographic connectivity.
Improve security where data lines have not been ciphered.
Reduce operational costs versus traditional WAN.
Reduce transit time and transportation costs for remote users.
Simplify network topology in certain scenarios.
Provide global networking opportunities.
Provide telecommuter support.
Provide broadband networking compatibility.
Provide faster ROI (return on investment) than traditional carrier leased/owned WAN lines.
Show a good economy of scale.
Scale well, when used with a public key infrastructure.
