Chapter 1. Networking Fundamentals
When it comes to theory, some of you out there might find it boring to read; so the first thing that may go through your mind is to skip this chapter. Don't do it. Even if you think that you know all the theoretical concepts, a recapitulation is good anytime.
Network professionals talk about protocols, devices, and software in terms of which OSI Layer they function at. When people talk about high-performance Layer 3 switches these days, they talk about switches that can perform OSI Layer 3 tasks and they expect you to know which tasks are at that layer. A simple deduction makes you realize that classic switches perform OSI Layer 2 functions.
Layer 3 switches are beyond the scope of this book, but that was a simple example of why you should know the OSI layered model, which is purely theoretical. Further in this book, you will learn about "Layer 7 filtering" which refers to how to filter what is on OSI Layer 7, which I'm sure you will find very attractive to read and implement.
By definition, a network is a group of two or more computer systems linked together, with the ability to communicate with each other.
The types of networks commonly used are:
- LAN (Local Area Network): A network in which the computers are close together (the same building).
- WAN (Wide Area Network): A network in which the computers are at very long distances.
- MAN (Metropolitan Area Network): A city-wide network.
- CAN (Campus Area Network): A network in a campus or a military base.
- SAN (Storage Area Network): A high-performance network used to move data between servers and dedicated storage devices.
- VPN (Virtual Private Network): A private network built over the public network infrastructure (over the Internet).
- HAN (Home Area Network): A network in a personal home. This term is rarely used; most people use the term LAN in this matter.
Computers in a user home network (a HAN) are usually connected to the building switch and form a LAN with the other users' computers. This switch is connected to a MAN or a CAN that is connected to the largest WAN, which is the Internet.