IPsec, as the name implies, is a protocol suite that operates on the Internet layer of the four-layer network model (and the Network layer of the OSI model). It is the only protocol of the three discussed here that operates on this layer. Because it operates on the Internet/Network layer, it is capable of encrypting and authenticating the entire IP packet, thus not only ensuring privacy for our data, but also ensuring that the packet's final destination is kept private as well. Thus it differs from both OpenVPN (which offers encryption, but operates on the Application layer) and the Layer 2 Tunneling Protocol (which does not encrypt data at all).
As a protocol suite, IPsec is actually a group of protocols, which in combination provide ...
