Types of VPN and the Role of Network Operator in Administering Them

Currently, a plethora of approaches to creating VPNs exists, and, because of ongoing vigorous
activity by standards bodies, you are apt to see methodologies continue to proliferate, at least
in the midterm.
Probably the most basic distinction among the several types has to do with the layer of the
network stack in which VPN creation takes place. All variants may very generally be placed
within three basic categories, though inevitably there are various degrees of hybridization.
The first category consists of subscriber-managed VPNs that are essentially applications.
The second category is comprised of service provider implementations where layer 2 switching
is utilized to segregate VPN traffic. Finally, the third consists of those service provider realizations
where layer 3 routing defines the traffic flows.