Computer Networks

What is a computer network?

computer network grade 9
Computer network

A computer network is a set of connected computers. We can create a computer network when two or more noted are connected. A computer is called as a node in a computer network. Those computers can be connected through wired or wireless connections. We will discuss it later in this lesson. Let’s learn basics of computer networks.

Types of network connections

transmission medium
Communication Model

The communication medium plays a major role in computer networks. A communication medium is a method we use to transfer the data through the network. It can be either a wired or wireless medium. The sender and receiver are two computers in the network. The protocols are a set of instructions and guidelines use to communicate.

Wired

The wired connection is differentiated from the wireless network connection from the physical cables that use for data communication. Let us discuss three common wired transmission mediums

Fibre Optic Cables

Fibre Optic Cables
Fibre Optic Cables

This is the most expensive wired medium which has the highest data transmission rate. Fibre optics often use in long-distance commination.  A fibre optic cable is a thin, flexible, transparent medium made of very fine glass or plastic fibres.

Twisted Pair Cable

twisted pair cable
Twisted Pair Cable

The name of the cable comes with two wires that are twisted around each other. These wires are the most used in a network as it is cheaper and have a considerable speed of data transmission. We can see those wires at our homes if we use a telephone.

Coaxial Cable

coaxial cable
coaxial cable for TV

The coaxial cable offers better data rates and it is consisting of a central copper conductor and surrounded by a copper shield. Normally we use coaxial cable to transmit signals from your Antenna to the Television.

Wireless

Wireless communication enables devices to connect remotely to a network without using physical wires. A wireless network uses infrared, Bluetooth, radio waves to share the information and resources between devices.

Infrared Waves

How a remote controller works using IR waves
Use of IR Wave in Remote Controller

Infrared (IR) is a common, inexpensive, easy to use wireless communication technology. It is useful for indoor areas and can be used only for short distances. These signals are unable to penetrate walls. We use IR signals in remote controllers.

Bluetooth

How bluetooth technology used
Bluetooth technology

Bluetooth technology is a short-range wireless communications technology to replace the cables connecting electronic devices, allowing a person to have a phone conversation via a headset, use a wireless mouse and synchronize information from a mobile phone to a PC. It is a high-speed wireless technology cover up to 10 meters distance. 

Wi-Fi Waves

wifi waves
Wi-FI Wave

Wi-Fi is a wireless network that uses radio waves. By using this technology, we can exchange information between two or more devices. Wi-Fi has been developed for mobile computing devices; such as laptops.

Radio Waves

Radio wave
Radio Wave

Radio waves are a type of electromagnetic radiation used in television, mobile phones, and radios. Long-range radio signals enable astronauts to communicate with the earth from the moon and carry information from space probes as they travel to distant planets. For navigation of ships and aircraft the radio range, radio compass (or direction finder), and radio time signals are widely used.

Main components of a computer network

A computer network is made up of several devices. Those components facilitate us to transfer data among the devices in the network. Let us discuss the basic components that you need to set up a network.

Server

Server computer
Server

Servers are computers that hold shared files, programs, and the network operating system. Servers provide access to network resources to all the users of the network.

Client

Client computers connected to a server in computer networks
Clients

The computers are the clients of the network. It can receive and send data to another computer. The above diagram shows several client computers connected to servers.

Network Interface Card (NIC)

Network Interface Card (NIC)
NIC

Each computer contains a NIC. Today this card comes with an inbuilt component of the computer motherboard. It is a must to have a NIC to connect to the internet. The main purpose of NIC is to format the data, send the data, and receive the data at the receiving node.

Switches/ Hubs

network switch
Switch
network hub
Hub

Both switches and hubs are hardware devices that connect multiple devices on a computer network. A switch contains more advanced features than a hub.

Routers

Network Router
Router

Routers are used to join multiple computer networks. Routers allowed us to connect our Local Area Network (LAN) to the internet.

MODEM

MODEM

The modem receives information from your ISP(Internet Service Provider – Ex: SLT, Dialog Broadband, Mobitel) through the phone lines, optical fibre, or coaxial cable in your home (depending on your service provider) and converts it into a digital signal.

Firewall

Computer firewall animation
Computer Firewall

A firewall is a network security device that monitors incoming and outgoing network traffic and decides whether to allow or block specific traffic based on a defined set of security rules.

How we connect the devices in a computer network?

The diagram below shows a typical local area network. As you can see in the picture the Server, Clients are connected through the switch. The wireless router allows connecting to the internet. The modem converts the signal into an analog signal.

Computer Network
Computer Network

Why we use computer networks?

We use a computer network to share resources and information. The devices like printer, scanner are limited resources. We cannot place a dedicated printer for each computer. Therefore, we share a single printer among computer networks.

The other reason that we use a computer network is communication. Computer users in the network can communicate through the network. We will discuss both uses below.

Sharing resources using a computer network

Computer networks allow us to share data, software, and hardware such as a printer. Most organization uses a computer network to share resources such as printers with all the connected devices.

Sharing software

As we know about the software licenses and paid versions of the software, we will have to pay a considerable amount of money if we use individual software licenses. However, buying multiple user software licenses for a computer network is relatively low cost.

Sharing a File/Folder

How folders display on shared location - File explorer
File Explorer

A file or folder can share within a network very easily and quickly. We create shared folders and users can access the shared folder. The above picture shows a shared file location. As you can see there are several folders in the shared location. In Windows, we can use the built-in file sharing option on File Explorer.

Sharing a Printer

Sharing a printer

The ability to share printers is one of the major draws of setting up a network. By setting up a network printer, you will be able to print from any computer in your home/ laboratory/ office.

Communication using a computer network

Lan Messenger

LAN Messenger is a free and open-source cross-platform instant messaging application for communication over a local network. It does not require a server. Several useful features including event notifications, file transfer, and message logging are provided. Currently, the platforms supported are Windows, Mac, and Linux.

LAN Messenger Sample work screenshots
LAN Messenger on Windows 7

Advantages of Computer Networks

Ability to access the Internet

Can use a single internet connection. It is a cost-effective and secure method to allow client computers to connect to the internet.

Ability to share software and hardware

Using network-connected peripheral devices like printers, scanners, and copiers, or sharing software between multiple users, saves money.

Ability to communicate with network users, using e-mail, short messaging services, etc.

The network allows us to communicate within the network and if it has full access to the internet then we get most of the benefits. We can use messaging software such as LAN Messenger or Instant Messaging services as Skype, WhatsApp, Viber to send files, messages among the users.

The common use of documents, images, photos, songs, videos, etc.

Sharing software such as computer games

Facility to save important information in a network storage device

Ease of taking backups since the data files are saved in a server computer in the network

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