An intranet by itself may help a company make better use of its computing resources, allow for better intra-company communications, and allow for the company to present a better face to the world. But for many corporations, that isn't enough. Many companies also need to do business directly with other business partners, such as subcontractors, or companies from whom they're buying goods and services.
Intranets can help there as well. They can allow companies to do business directly with each other over the Internet - and to do so securely. The technology that allows this to be done is called Virtual Secure Private Networks (VSPNs) or Virtual Private Networks (VPNs). In essence, the technology allows two companies with intranets to create a "virtual" link between them across the Internet that is as secure as if they were connected via a private connection. VSPN technology can also be used to create a "virtual" intranet for a company that can link branch offices together over the Internet, while at the same time ensuring that the data that passes between them can't be seen by anyone except people in the "virtual" intranet.
These VSPNs can save corporations a substantial amount of money, both for communicating with business partners and for hooking together branch offices. Today, businesses commonly spend significant amounts of money every month leasing private lines that no one else can use. The data sent along these private lines cannot be seen by anyone else; they are used by the company only. Because of that, they are secure from prying eyes. If, however, there were a way to link company's intranets over the Internet, there would be no need to pay for leased lines-all the traffic could be handled over the Internet. In addition to saving money on lines, the creation of secure links from intranet to intranet would also allow companies to communicate more effectively electronically, leading to more efficiency and even more in savings.
VSPNs use a combination of routing technology, encryption technology, and a technique called tunneling. When someone from one intranet wants to send information to another intranet via a VSPN, VSPN server software recognizes that the destination is a VSPN, and so knows to handle the data differently than if it is being sent to an unsecured site on the Internet. Using powerful encryption technology, the software encrypts the IP packets so that no one will be able to read it. It then places those IP packets inside an IP "envelope" or "wrapper." That envelope is essentially a normal IP packet, so it gets delivered as does any other data, via routers. No one can read what is inside the wrapper, though, because it has been encrypted. When packets are sent this way over the Internet, it is called tunneling.
On the receiving intranet, the VSPN software throws away the wrapper, and then decrypts the data inside of it. The data is then delivered over the intranet via intranet routers.
A Virtual Secure Private Network (VSPN) or Virtual Private Network (VPN) allows business partners, each of whom has an intranet, to send secure communications to each other over the Internet, and know that no one else will be able to read the data. In essence, it creates a private, secure channel between intranets, even though the data sent between them travels over the public Internet. This means that companies will not have to lease expensive lines between them to send data over a secure link. The technology can also be used to allow a company to link branch offices with each other, without having to lease expensive lines, and know that the data can only be read by people on the VSPN.