ile running fiber between buildings in a city is generally not possible. Usually, in a city, telecom providers are involved in delivering some sort of technology that allows connectivity through their networks. MANs and CANs may, in fact, be WANs. The differences are often semantic. If two buildings are in a campus, but are connected via frame relay, are they part of a WAN, or part of a CAN? What if the frame relay is supplied as part of the campus infrastructure, and not through a telecom provider? Does that make a difference? If the campus is in a metropolitan area, can it be called a MAN? Usually, a network's designers start calling it by a certain description that sticks for the life of the network. If a team of consultants builds a WAN, and refers to it in the documentation as a MAN, the company will probably call it a MAN for the duration of its existence. Add into all of this the idea that LANs may be connected with a CAN, and CANs may be connected with a WAN, and you can see how confusing it can be, especially to the uninitiated. The point here is that a lot of terms are thrown around in this industry, and not everyone uses them properly. Additionally, as in this case, the definitions may be nebulous; this, of course, leads to confusion. You must be careful about the terminology you use. If the CIO calls the network a WAN, but the engineers call the network a CAN, you must either educate whom- ever is wrong, or opt to communicate with each party using their own language. This issue is more common than you might think. In the case of MAN versus WAN versus CAN, beware of absolutes. In other areas of networking, the terms are more specific. Chapter 1: What Is a Network? For our purposes, we will define these network types as follows: Local Area Network (LAN) A LAN is a network that is confined to a limited space, such as a building or floor. It uses short-range technologies such as Ethernet, Token Ring, and the like. A LAN is usually under the control of the company or entity that requires its use. Wide Area