There are many components for a communication network. The basic three components are a host computer, a client, and a circuit. Besides these components, others include front-end processors, teleprocessing software, input terminals, and specialists.

Host Computer (Server)

The host computer or server (a mainframe, minicomputer, or microcomputer) is the main unit in the communication network. It stores data and programs that can be accessed by the clients. The host computer is responsible for performing the data processing tasks of the network. After processing has occurred, the data or information is routed back to a front-end processor. In distributed processing or client-server computing, several host computers may be tied together by the data communication network.

The client is a hardware device (a terminal or microcomputer) at the opposite end of a host computer of a communication circuit. It usually provides end users with access to the data and software on the server. The client is an input/output device.
The most widely used computer input/output devices for a communication network are the terminals. There are several types of terminals in common use in business today. The most familiar type of input/output terminal for most end users is the keyboard terminal. This terminal usually has a keyboard as an input device and a monitor and/or a printer as an output device. Push- button telephones can also be used as input/output terminals in computer-controlled communications networks. This type of terminal represents the most readily accessible and least expensive terminal in common use today. There are many special purpose terminals. One is a point of sale (POS) terminal. These terminals enable retailing institutions to instantaneously record sales data and update inventory records at the time of sale. Another is a data collection terminal. The term data collection terminal refers to a type of terminal which can collect information on the ongoing performance of factory employees. A remote job entry (RJE) terminal is another type. It is used in situations in which large amounts of information must be printed out at a remote location. A cash register used in many fast-food restaurants is another special type of terminal. It can update sales and inventory records.

The circuit is a communication channel that allows the data and information to move through the pathway. It includes several types of lines, such as twisted wires, coaxial cables, and fiber optic cables. It also contains wireless transmission circuits such as microwaves and satellites, and it is becoming more popular.

The front-end processor handles the incoming and outgoing communications exchanges between the host computer and the peripheral terminals and other host computers both inside and outside the network. Thus, the front-end processor serves as both an input unit and output unit for the host computer. Usually, the front-end processor is a minicomputer, while a mainframe serves as the host.

Certain front-end processors can send messages from one terminal to another without involving the host computer. This ability is known as message switching. Front-end processors that perform message switching usually have a store and forward capability. When a terminal is unable to receive a transmission at a particular time, the front-end processor will hold the message in its secondary storage and resend it later.

Besides the hardware mentioned previously in this chapter, the host and the front-end processor must contain software in order for the network system to run effectively. Software may also be located in the terminals and the cluster control units. The types of software located in the host and the front-end processor will be discussed here.

• TCM: The teleprocessing software located in the host computer is known as the TeleCommunications Monitor (TCM). The typical functions of the TCM include: Setting priorities of incoming messages, providing network security, settling an interface between the teleprocessing system and the DBMS (database management system), and saving the contents of primary storage to secondary storage.

• NCP: The Network Control Program (NCP) is the name for the software located in the front- end processor. Its main functions are: determining if a terminal desires to obtain access to the network, organizing data and information within the network by stamping date and time, translating the codes received from other types of computer system, inspecting format errors in incoming delivery, saving recent incoming messages in secondary storage, and maintaining statistical records on network activity.

Obviously, the growing importance of networks in business organizations will lead to an increase in the number of specialists who can manage these data communications systems. This section discusses the role of a network manager and his or her staff in a corporate environment. The network manager is responsible for performing all of the major management functions such as network planning, implementing, operating and controlling that relate to the communications system. The network planning and network controlling are the most important among them.

Network Planning

It involves anticipating the future computer-based communications needs of the organization. Network planning consists of three parts:

• Capacity planning involves estimating the quantity of data communications that will be required

• Staff planning consists of determining the number of employees that will be necessary to efficiently maintain the network system

• Performance monitoring consists of anticipating the effects of changes in the network's design.

Network Control

It involves activities in which the performance of the network is compared to predetermined standards to determine when corrective action or improvements are needed.