About the end of the 1990s the industry began to realize that their networks that were then connected by incredibly expensive leased or owned lines or dial-up phone lines, could be securely connected across shared public lines and by the internet. All that was needed was a finely developed and implemented encryption and routing system so things would stay secure.
Why would VPNs be desirable?
They vastly reduce network costs because they do not have a need for the leased communications lines that network locally or to the internet. The users can also exchange private data securely and make use of their own network’s secure systems. VPN technologies have many options for usage and various protocols. They are adaptable to a great number of technologies and marketing influences. They are not easily defined because they are so incredibly flexible in make-up and usage.
What can VPNs do?
An easier question to answer would be,”What can’t they do?”. VPN technologies can use vastly different protocols to tunnel data traffic. They can be totally adjusted as to the tunnel’s termination point. Their connectivity is adjustable to site-to-site or remote access. They can provide various levels of security inside and outside of the same network, while at the same time remaining adjustable as to which layer, (2 or 3), the circuit connectivity can be set at. They can provide fully secure encrypted mechanisms and mechanisms that run right along side with little or no security. In short, the number of protocols is almost without limit.
VPNs continually support changing sets of network nodes that fluctuate arbitrarily. VPNs are highly sophisticated networks, but since they are so flexible, they often are seen simply as tunnels running basic routing protocols. With provider-provided VPNs (PPVPNs), we have a different concept completely. Here they continually support multiple VPNs that operate at the same time over the same network by the same service provider, while being “hidden” from each other.