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Unit III: Introduction to Computer Networks
6 COMPUTER NETWORKS
Chapter Outline
6.1 Components of a Computer Network 6.2 Evolution of Networking
6.3 Network Topologies 6.4 Network Types
6.5 Network Devices
Friends communicate with each other on social networks, for example, relatives, classmates, and people in a Facebook
group form social networks. A computer network is a collection of interconnected computers in the same spirit. It provides
a means of communication amongst the computers in a network to share hardware and software resources. The Internet
is the largest computer network. Computers connected to the Internet can share information amongst themselves. There
are several applications of computer networks such as collaborative learning, scientific research, video-conferencing,
online gaming, e-shopping, e-governance, telehealth, and chatting. This chapter will discuss what constitutes a computer
network, its categorisations, functionalities, and the technologies that make it work and briefly about the Internet.
Computer Networks: Set of devices connected via links.
6.1 Components of a Computer Network
The main components of a network are entities participating in the network, the medium through which communication
takes place, and the content to be communicated. Children in a kindergarten class communicate with the teacher and
themselves without being aware of any communication support. Of course, we know that communication is made
possible by the air present in the room that serves as a medium (also called a channel) through which sound waves
travel from one person to another. In this example, the students and the teacher form the entities, the air is the
medium, and the conversation in a natural language is the content. Similarly, the computers communicate with each
other by exchanging (sending and receiving data) the content in the form of binary data. The participating computers
agree on the norms of communication. Transfer of data between computers (also called nodes or terminals) via some
channel is called data communication.
Figure 6.1 shows a communication system comprising the following components:
• Sender: The node that sends the data.
• Receiver: The node that receives the data.
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