VPN, Virtual Private Network

Unlike many networks, a VPN is not required to use explicit security features such as data encryption and authentication. For instance, it can be used to separate the traffic generated from different users over an underlying network that has reliable security already implemented. In general, a VPN consists of a more complex topology than PPP (Point-to-Point Protocol). The characteristics that distinguish it from other protocol are not associated with speed, performance or security, but the capability to overlay other networks and provide a level of functionality that is more convenient to a large community of users. Tunneling protocols that implement Point-to-Point topology aren’t necessarily considered as VPNs. This is because a VPN is expected to support changing groups of network nodes. Since many routers are supported by a software tunnel interface, a VPN is often considered to be a collection of tunnels in which traditional network routing takes place.