Understanding Computer Networks
Each day, students and faculty at State University sit down in front of a PC or UNIX workstation and eagerly check their electronic mail, surf the World Wide Web, or run applications such as word processors and analysis packages. To most users, the magical wire which carries all of this information is nothing more than an electrical construct; two pair of wires twisted together and crimped at the end with phone connectors. Our world today is built on networking in every field from cable television to telephone systems, yet many engineers, old and young alike, have no idea what constructs enable them to communicate seamlessly across the globe.
Computer technology is constantly evolving. Fifteen years ago, computers were connected via simple serial interfaces communicating at 9600 bits per second. Today, workstations pump out data at rates in excess of 100,000,000 bits per second, and the road to improvement seems endless. The networking industry is filled with jargon which make it difficult to understand. While the concept of networking is not difficult to grasp, it is often difficult to fully explain. This text will enable the reader to understand the basic hardware that allows a computer network to function.
Computer networks consist of five major components. Two of these components are probably familiar to you: the workstation and the network server. When you sit down at a networked computer, the first thing you do is type in your name and a password. This process allows the computer to recognize you, and verify you are who you say you are by means of a password. When the login process is complete, you are connected to a network server; a device that simultaneously manages the disk space and computing resources for every user on the network. These resources might include electronic mail, file storage space, and CPU time, for example.
Other pieces of the network take care of connecting workstations and network servers together. These devices are called repeaters, switches, and routers. These devices form the network infrastructure that allows you to communicate to servers, to other workstations, and to other computers connected via the internet.
The repeater, or hub, is the simplest piece of networking infrastructure. A repeater has a certain number of ports, each of which is attached via a cable to your computer. The repeater functions much as its name implies; whatever is received on any one port is simultaneously repeated to all the other ports on the repeater.
When a computer wants to talk to the network, it listens to the wire to see if anyone else is talking. If it detects no traffic on the wire, the computer sends out a signal indicating that it is about to start a conversation. At the same time, it listens to make sure no one else is about to begin talking. This signal is repeated to every computer connected to the repeater, and is called a carrier. If two computers decide to talk at...