The TCP/IP Guide  9  Networking Fundamentals       9  Types and Sizes of Networks

Types and Sizes of Networks 1 2 Segments, Networks, Subnetworks and Internetworks

Two of the most basic ways that networks are differentiated and contrasted are the relative distances between the devices that they connect, and the general mechanisms used to communicate between them. The reason for making these distinctions is that the technological needs of a network differ greatly depending on the amount of ground you are trying to cover, and also on the overall way that you want to transmit and receive information.

Many people, including me, like to divide the many kinds of networks in existence into three general classes:

• Local Area Networks (LANs): Networks that connect together computers that are relatively close to each other—generally, within the same room or building. When most people think about networking PCs and other small computers, this is what they usually have in mind. The vast majority of regular LANs connect using cables, so the term “LAN” by itself usually implies a wired LAN, but not always.
  
  
• Wireless Local Area Networks (Wireless LANs or WLANs): Local area networks that connect devices without wires, using radio frequencies or light. WLANs can be entirely wireless, but most are not: they usually connect wireless devices to each other and also to the wired portion of the network. Due to the limits of most wireless technologies, wireless LANs usually connect devices that are very close to each other, generally within a few hundred feet at most.
  
  
• Wide Area Networks (WANs): Networks that connect together devices or other networks over a greater distance than is practical for local area networking. If the distance between devices can be measured in miles, you will generally use WAN and not LAN technology to link them.
  
  More often than not, WANs are used to link together physically distant LANs. For example, a company with locations in two different cities would normally set up a LAN in each building and then connect them together in a WAN. I also consider most Internet access technologies to be a form of wide area networking, though some might not agree with that. There is also the term wireless WAN (WWAN), which just refers to a WAN that uses wireless technology.

Types and Sizes of Networks 1 2 Segments, Networks, Subnetworks and Internetworks