Absolute OpenBSD, 2nd Edition

Network Layers

The network protocol is divided into several layers. Each layer handles a specific task and interacts only with the layers immediately above and below it. At first, you might laugh at the idea that this layer model simplifies the network process, but it really does. The important thing to remember right now is that each layer communicates with only the layer directly above it and the layer directly beneath it (theoretically, anyway).

The classic Open Systems Interconnection (OSI) network protocol stack represents the network as seven layers. It’s an exhaustively complete model and covers almost any situation using any network protocol and any application. Because the Internet is a very specific type of network, and because this ...