Section 1 Introduction
Computer communications is the process of sharing data, programs, and information between two or more computers. We have discussed numerous applications that depend on communication systems, including: • E-mail – Provides a fast, efficient alternative to traditional mail by sending and receiving electronic documents. • Instant messaging – Supports direct, “live” electronic communication between two or more friends or buddies. • Internet telephone – provides a very low cost alternative to long-distance telephone calls using electronic voice delivery. • Electronic commerce – buying and selling goods electronically In this chapter, we will focus on the communication systems that support these many other applications. Connectivity, the wireless revolution, and communication systems are key concepts and technologies for the 21st century.
Networking is a concept related using computer networks to link people and resources. For example, networking means that you can connect your microcomputer by telephone or other telecommunications links to other computers and information sources almost anywhere. With this connection, you are linked to the world of larger computers and mainframes and their extensive information resources. Thus, becoming computer competent and knowledgeable becomes a matter of knowing not only about connectivity through networks to microcomputers, but also about larger computer systems and their information resources.
A computer network is a communication system that connects two or more computers so that they can exchange information and share resources. Networks can be set up in different arrangements to suit user’s needs
There are a number of specialized terms that describe computer networks These terms include:
• Node- any device is connected to a network. It could be a computer, printer, or data storage device • Client – a node that shares resources with other nodes. Dedicated servers specialize in performing specific tasks. Depending on the specific task, they may be called an application server, communication server, database server, file server, printer server or Web server. • Server – a node that shares resources with other nodes. Dedicated servers specialize in performing specific tasks. Depending on the specific task, they may be called an application server, communication server, database server, file server, printer server or web server. • Hub- the center or central node for other nodes. This device can be a server or simply a connection point for cables from other nodes. • Network operating systems (NOS)- control and coordinate the activities of all computers and other devices on a network. These activities include electronic communication and the sharing of information and resources. • Distributed processing - a system in which computing power is locate and shared at different locations. This type of system is common in decentralized organization where divisional offices have their own computer systems. The computer systems in the divisional offices are networked to the organizations main or centralized computer. • Host computer – a large centralized computer, usually a minicomputer or a main frame. • Network manager - a computer specialist, also known as network administrator, responsible for efficient network operations and implementation of new networks.
A network may consist only of microcomputers, or it may integrate micro-computers or other devices with larger computers. Networks can be controlled by all nodes working together equally or by specialized nodes coordinating and supplying all resources. Networks may be simple or complex, self-contained or dispersed over a large geographical area.
1.4 LOCAL AREA NETWORKS
Networks with nodes that are in close physical proximity – within the same building, for instance – are called local area networks...
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