Virtual Private Networks (VPN)

A Virtual Private Network (VPN) is a private network that uses a public network (such as the internet) to connect remote sites or users. VPNs use virtual connections routed through the internet, instead of using dedicated leased line connections. VPN enables distance users to work together. Distant users gain access to the company's private LAN through the internet, so they remain as a part of the private network accessing the company's resources.
The following features are needed for a well-designed VPN:

• Security
• Reliability
• Scalability
• Network and Policy Management

When talking about VPNS, there are three types of VPNs. They are,

• Remote-Access VPN
• Site-to-Site VPN
• MPLS based VPN

Remote-Access VPN
These are also called Virtual Private Dial-up Networks (VPDN).