The open system interconnection model is a means by which network protocols can be implemented. It involves seven different layers of communication, which are divided into a hierarchy. The layers are the Application layer, the Presentation layer, the Session layer, the Transport layer, the Network layer, the Data Link and the Physical layer. They are numbered from seven to one in the same order.
Where VPN networks are concerned, they are defined by which layer is used to provide security. Encryption can occur at different layers. Depending upon which layer the encryption occurs at, different levels of traffic will be encrypted. When you purchase a VPN service, the layer on which it functions is important information.
At the Application layer, a VPN will work with specific applications. The most common example of this type of VPN network is seen over the SSL connections that people use to purchase items online every day. The Application layer VPN provides encrypted communication between the web browser that the visitor is using to view the item and the server that is used to process the order. There are other applications that can be protected in this way, as well. This type of VPN security requires that each different application be supported.
A Network layer VPN functions on layer 3. Unlike Application layer VPN security, Network layer VPN security will encrypt any traffic, regardless of the different applications being used. This type of VPN is used by some of the most well-known names in Internet security. For example, Cisco uses this layer for VPNs. These VPN servers are sometimes provided under the names L2TP and GRE.
Data Link VPN is used when two private networks need to communicate. It is one of the most expensive types of VPN connection. Normally, the protocol used over these connections does not provide encryption, so encryption needs to be added to the connection.
Depending upon your security needs, you should be aware of how any of the applications you use are encrypted or not encrypted by your VPN service and how your Internet browsing traffic is encrypted or not encrypted by your VPN service. Most commercial VPN providers specify which type of encryption you’re buying and, in addition to VPN services, many of them offer SSH tunneling, as well.
If you’re concerned about security and anonymity on the Internet, VPNs are the best solutions, but not all of them function in exactly the same way. You can learn more about VPN services on our best VPN services page.