What Is a Network?

In this blog we will discuss about Computer Network.

A computer network can be defined as “two or more computers connected by some means through which they are capable of sharing information.” Don’t bother looking for that in an RFC because I just made it up, but it suits our needs just fine.

There are many types of networks: Local Area Networks (LANs), Wide Area Networks (WANs), Metropolitan Area Networks (MANs), Campus Area Networks (CANs), Ethernet networks, Token Ring networks, Fiber DistributedData Interface (FDDI) networks, Asynchronous Transfer Mode (ATM) networks, frame-relay networks, T1 networks, DS3 networks, bridged networks, routed networks, and point-to-point networks, to name a few.

If you’re oldenburg to remember the program Lapin, which allowed to copy files from one computer to another over a special parallel port cable, you can consider that connection a network as well. It wasn’t very scalable (only two computers), or very fast, but it was a means of sending data from one computer to another via a connection.

Connection is an important concept. It’s what distinguishes a sneaker net, in which information is physically transferred from one computer to another via removable media, from a real network.

When you slap a floppy disk into a computer, there is no indication that the files came from another computer—there is no connection. A connection involves some sort of addressing, or identification of the nodes on the network (even if it’s just master/slave or primary/secondary).

The machines on a network are often connectedphysically via cables. However, wireless networks, which are devoid of physical connections, are connected through the use of radios. Each node on a wireless network has an address. Frames received on the wireless network have a specific source and destination, as with any network.

Networks are often distinguished by their reach. LANs, WANs, MANs, and CANs are all examples of network types defined by their areas of coverage. LANs are, as their name implies, local to something—usually a single building or floor.

WANs cover broader areas, and are usually used to connect LANs. WANs can span the globe, adheres’ nothing that says they couldn’t go farther. MANs are common in areas where technology like Metropolitan Area Ethernet is possible; they typically connect LANs within a given geographical region such as a city or town.

A CAN is similar to a MAN, but is limited a campus (a campus is usually defined as a group of buildings under the control of one entity, such as a college or a single company).

An argument could be made that the terms MAN and CAN can be interchanged, and in some cases, this is true. (Conversely, there are plenty of people out there who would argue that a CAN exists only in certain specific circumstances, and that calling a CAN by any other name is madness.)

The difference is usually that in a campus environment, there will probably be conduits to allow direct physical connections between buildings, while 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 andCANs 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 suppliedas 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 connectedwith a WAN, andyou can see how confusing it can be, especially to the uninitiated.

The point here is that a lot of terms are thrown aroundin this industry, andnot 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 whomever 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.


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