ICT

Key Unit Competency: By the end of this unit, you should be able to:

1. Identify computer network devices, medium and peripherals. 

2. Connect different computer devices to the network. 

3. Use social media to exchange information on social life.

Introduction 

Sharing of information is vital within organisations and institutions locally, nationally, regionally and internationally.  

Due to technological developments, sharing of information is made possible through Internet connectivity. Indeed, the term Global Village is now commonly used to refer to the world. This is because the world is today considered as a single community where members are connected by electronic communications.

Electronics and technology refer to devices such as computers and mobile phones that enable people to easily communicate and share information through Internet connectivity. A person can communicate with friends and relatives within Rwanda, Africa and even the entire world. 

8.1 Definition of network and computer network 

The term network refers to a collection or a group of interconnected objects or people. A computer network refers to a set of computers that are connected together for the purpose of sharing resources. 

The most common way of connecting computers is through the Internet. Examples of resources that are shared through a computer network are printers or a file server.

 A computer network is also defined as set of interconnected computing nodes that are organised in such a way that they can exchange data, information, or resources. A node is a connection point in a computer network. Devices such as a personal computer, laptop, cell phone, smart phones, tablet, scanners and printers are examples of nodes. 

8.2 Devices that can be connected to a network 

Computers in a network  are connected through a transmission medium using a set of rules called protocols. In computing, a protocol or communication protocol refers to a set of rules in which computers communicate with each other.

 Devices that can be connected to a network are also referred to as Data Terminating Equipment (DTE) or computing nodes. Examples include desktops, laptops, printers, scanners, PDAs, smartphones and the server.  

A server is an application program that provides services to other computer programs in a network. Note that the computer on which the server application program runs is also referred to as a server. 

 Figure 8.1: Devices connected in a computer network 

8.3 Connecting different Devices to the Computer Network

Through technology, any of the devices shown in Figure 8.1 can be connected to a computer network through the use of cables, or through wireless connectivity.

8.3.1 Connecting Devices Using Cables

To connect devices in a computer network, you can use cables. There are different types of cables. 

The cables are connected to the devices through an Ethernet port. An Ethernet port is a socket on a computer that allows one to connect devices to a computer network.

An Ethernet port is usually found on networking devices, such as computers, routers, and television sets. Devices are connected in a network through an Ethernet cable.

Figure 8.2: An Ethernet port and cable

Figure 8.3: Computers in an Ethernet network

8.3.2 Connecting Devices Using Wireless Media 

As the word wireless suggests, it means without wires. A wireless computer network, therefore, does not require a cable of any kind for connection. Sometimes the wireless network is also referred to as a Wi-Fi network. Wi-fi stands for Wireless Fidelity. It is a technology that allows computers, smart phones, or other devices to connect to the Internet or communicate with one another in a wireless network. The use of a wireless network enables devices to be connected to a network without the process of introducing cables into buildings. Instead, the devices are connected by radio waves.

In a wireless network there is a component called the wireless router or access point. 

The wireless router or access point should be installed in a way that ensures that the network coverage is wide. In a large area, one may require more than one access point in order to have adequate coverage. One can also add access points to the existing wireless router to improve coverage.

Figure 8.4: Devices connected in an wireless network 

In Windows 10 that you covered in Senior 1, you can connect to a wireless hotspot using your laptop. 

A wireless hotspot is an area covered by a usable signal that allows wireless connection to the Internet or to some other computer network.

 Wireless connections are secured by use of passwords. To connect to a locked hotspot, you must know the password.

Figure 8.5: A laptop screen showing wireless connections available 

Computers in a network share resources. Network resources refer to forms of data, information, hardware devices, and software that can be accessed by a group of computers through the network. Network resources are also known as shared resources

Shared resources are important in work environments where collaboration is essential to success. 

Network Services 

The term network services refers to software and connectivity tools that are installed in a network. Network services are managed by a central server and are then distributed to the networked computers. The computers are able to access the shared files and other services from a central location. 

In a computer network, the desktops connected are known as client computers or workstations.  

The server may be located in a different room or building away from the workstations. The networked services are accessed through network cables  or through a wireless network. Through the network, data is  transferred within the network. Cables or wireless network connection also provide access to the Internet. 

Some of the services offered by a network include: 

• User management 

• System administration 

• Email services    

•Shared printing 

•File sharing   

• Shared computer software

1. User management 

• This involves the creation of user accounts. Each account contains user names and their respective passwords. 

• It also involves allocation of user access rights and privileges to ensure data protection. 

• For example, when a student joins a school, the network administrator creates a new account for the student to be able to access the network services. A network administrator is also called a systems administrator. This person manages the network in a school or  organisation. 

The network administrator ensures that the computer network is up to date and running smoothly.

2. System Administration 

• The system administrator is able to control all the computer users from a central location. 

• The administrator is able to view what each user is doing with their computer and even control the kind of programs that the users can access.

 • The system administrator can add new programs or update existing software from the network. This increases the overall quality of the network and reduces staff time spent on computer maintenance. 

3. Email Services 

• These are also known as webmail or online email services.

• Email services enable users in a network environment to send, receive and review e-mails from their workstations. 

• Email services offer easy access and storage of e-mail messages for users. 

• When logging into an email service, users type in their username and password. The messages are stored on the provider’s server. 

4. Shared Printing 

• A printer is connected to a computer within a network. 

• The shared printer can be used by all other computers within the network instead of having each computer connected to its own printer. 

5. File sharing 

• A computer network enables users to share files.

• You were introduced to Windows 10 in Senior

1. This operating system has the feature that allows you to share your files with others and access their files as well. 

• The Share tab in the File Explorer has different tools and options you can use to share files within a computer network. 

• File sharing allows students to collaborate when doing a project.

Figure 8.6: File sharing in a computer network 

6. Shared Computer Software 

• A computer network allows users to share software. Users do not have to install the application software on their different computers. The software is hosted on the server. In this way, the individual computers do not have to utilise disk space for installation.

 8.5 Network Medium 

It is also known as transmission media or channels. They facilitate interconnection of computers and other devices in a network by providing a pathway through which data and information is carried from one point to another. Examples of transmission media are cables and radio waves. 

8.5.1 Cables

They are also known as bounded or guided media. Data signals are carried from source to destination through a physical pathway that is restricted. They are made up of a conductor protected by a jacket insulating material.

There are three types of bounded media, namely Twisted Pair Cable, Coaxial Cable, and Fibre Optic Cable.

1. Twisted-pair cable

This is a cable made up of pairs of insulated copper wires twisted along each other. The twists are done to protect the cable from crosstalk. 
Crosstalk is interference that is caused by one or more wires. Crosstalk can cause errors, noise, or prevent cables from transmitting accurate data. They are usually packed as four sets of pairs in a cable. There are two types of twisted pair cables namely: Unshielded Twisted Pair (UTP) and Shielded Twisted Pair (STP). 

2. Unshielded Twisted

Pair This is a type of twisted pair cable where each pair is not shielded from the others and hence the name unshielded twisted pair. This cable is vulnerable to noise whose source could be radio signals, radiation from spark plugs in motor vehicles and lightening sparks. 

3. Shielded Twisted Pair

Each twisted pair has a shield around it protecting the pair from others.  The shielding minimizes electromagnetic interference, as well a cross-talk from neighboring pairs. 

Figure 8.7: Types of twisted cables 

Advantages of  Twisted Pair
  
• It is easy to install.
• STP cables yield maximum bandwidth regardless of the external conditions.The shielding, however, makes the cable heavier and more difficult to bend.
• Cost of installation is low since the cables are readily available in the market.
• STPs are commonly used by large-scale companies in high-end applications that require the maximum bandwidth.
• It can only up to a maximum of 100Mbps (Megabits per second).

Disadvantages of  Twisted Pair

• It is very sensitive to Electromagnetic Interference compared to other cables.
• UTP has a great disadvantage in that it has a limited bandwidth, which restricts long distance transmission with low error rates.

4. Coaxial Cable

This type of cable contains two conductors, namely copper wire which runs through the centre of the cable where the actual data travels and a shield made of wire mesh tube, metallic foil, or both.    

Figure 8.8: Coaxial cables

The copper wire is surrounded by plastic insulator which is covered by a conducting shield that acts as a return path and also filters Electromagnetic Interference (EMI). 

The outer jacket which also acts as an insulator forms a protective covering for the cable. It resembles the cable used for connecting a television (TV) aerial to the TV set. It carries data in form of electrical signals.

There are two types of coaxial cable, namely thinnet and thicknet. Thicknet is also called thickwire and thinnet and called Thinwire. Thicknet and thinnet are commonly used terms for the larger and smaller size of coaxial cable used in Ethernet local area networks.

Advantages of Coaxial Cable

• It can carry data, voice and video signals. Therefore, it is commonly used in TV aerial cables.
• It is more resistant to radio and electromagnetic interferences (EMI) hence more stable than twisted pair. 
• It can transmit up to one Gigabite per second (1Gbps).

Disadvantages of Coaxial Cable

• They are more expensive to buy as compared to twisted pair cables.
• Installation cost is high compared to twisted pair cables.

5. Fibre Optic cable 

This type of cable uses glass material strands or fibres which are as thin as a human hair. Fibre optic cables carry digital information over long distances.

Figure 8.9: Fibre optic cable

Light is used to transmit data signals unlike in coaxial and twisted pair cables which use electrical signals. The electrical signal from the computing node is converted to a light signal using a Light Emitting Diode (LED) or lasers and then they are transmitted through the cable. At the receiver the light signals are converted back to electrical signals by a photosensitive device.

Advantages of fibre optic cable

Note the following facts about fibre optic cables: 

• Fibre is thinner and smaller than other types of cabling such as copper. They are therefore lightweight. They are suitable for situations where space is limited.

• Fibre optics have more bandwidth. This means that fibre optics can carry more information with far greater efficiency than cables. This translates to faster internet speed.

• Fibre optic cabling is easier to work with and transport.

• Fibre optics are more secure.

• Fibre optics are more efficient. Signals sent over fibre optics do not reduce nearly as quickly as those sent over copper wiring. There is nearly no signal loss in many situations.

• Fibre optics use less energy. Lower energy requirements means that fibre optics are more friendly to the environment.

• Fibre optics use light. Since there is no electrical current passing through a fibre optic cable, there is no heat. No heat means that fibre optic cabling is not a fire hazard in the same way that metal wiring is.

• Fibre optic cables are not affected by weather conditions such as changes in the temperature, rain, cold, or any other environmental conditions.

• Fibre optics are faster. Data is transmitted faster because of the increased capacity of fibre optic cables.

• Fibre optic cables are immune to Electromagnetic Interference (EMI). They do not generate electrical signals hence can be used in dangerous places such as flammable areas.

 Disadvantages of fibre optic cable

• They require expensive connectivity devices and media.

• Their installation is a delicate process because the cables must be handled carefully.

• They are relatively complex to configure.

• A broken fibre optic cable is difficult and expensive to repair.

8.5.2 Wireless Connectivity 

1. Radio waves

They travel just like surface water waves that is, when an object is dropped in a body of water,

waves move out from the object in all directions (omnidirectional). This means that radio waves

start from a central point and spread outwards over the covered area hence they travel in all

directions from the source.

As they travel outward, their energy spreads outwards over the covered area.

They have no physical link between sender and receiver. They are also known as unbounded, unguided

or wireless media. Usually radio waves are sent through the atmosphere.

At the source there is a transmitting antenna which propagates the signals and at the destination

there is a receiver antenna which collects the signals.

Radio waves are used in radio and television broadcasts, but they can also be used to transmit data. Radio waves can be of High Frequency (HF), Very High Frequency

(VHF) or Ultra-High Frequency (UHF).

2. Infrared transmission

Infrared does not penetrate walls or solid objects hence security and interference problems are not encountered. There is no frequency allocation issue since no licence is required. This technology is used in TV remote control and wireless computer networking. 

For transmission to take place, there must be a transceiver to aid in the communication. Transceivers must be in close range with each other, either directly or via reflection from a light-coloured surface such as the ceiling of a room.

3. Bluetooth

This is a technology that enables the connection of electronic devices over a short distance of up to about 10 metres creating a Personal Area Network (PAN) with a high level of security.

This technology can be used with cell phones, personal computers, laptops, printers, digital cameras and telephones among others. It is also an example of radio transmission technology. It is not licensed, therefore, communication takes place at no cost. To connect a laptop to a Bluetooth network, do the following:

(i) Click on the Bluetooth icon on the task bar as shown in Figure 8.10.
(ii) Ensure that the Bluetooth feature in the other device is activated.

(iii) Click on Add a Bluetooth Device for the system to automatically locate a nearby Bluetooth device. 

(iv) Pair the devices then click Join a Personal Area Network.

Figure 8.10 : Connecting via Bluetooth 

4. Wi-Fi (Wireless Fidelity) 

It is a wireless networking technology that uses radio waves to provide highspeed Internet and networking connections. Examples of WiFi-enabled devices include laptops, cell phones, tablets, iPads, peripheral devices such as printers and keyboards among others. They communicate with a single computer which is fitted with a WiFi adapter. 

Advantages of wireless communication 

• Allows users of the network to roam without losing access to the network. 

• It is easier to add and remove nodes. 

• It is ideal for use in networks that cover a wider geographical area. 

• Enables communication in remote areas where the laying of cables is not possible. 

Disadvantages of wireless communication 

• Initial installation cost is very high. 

• Security of information can be compromised since it can be easily tapped. 

• Speed is slower than the use of fibre optic.

8.6 Computer Network Devices 

They are communication devices that are used in networking. They are used in between the DTE and transmission media to provide an interface or junction for the network to be fully operational. 

They are also known as Data Circuit Terminating Equipment (DCE). Examples of computer network devices include: Switch, Hub, Access Point, Router and Multifunctional device. 

8.6.1 Hub 

A hub is a connection point in a network. The hub connects many computing nodes together and is able to send signals from one node to another on the same network.

Figure 8.11: A hub that has devices connected to it 

A hub connect networks that have the same rules and it transmits signals by broadcasting them to all the computing nodes in the network. 

8.6.2 Switch 

A switch is similar to a hub in physical structure except that it forwards data directly to its destination address without broadcasting it to all the other nodes in the network. Figure 8.12 shows computers in a network connected through a switch.

Figure 8.12: Computers connected to a network switch

In order for a switch to be able to perform its function, it has to keep records of the addresses of all the nodes in the network.

When a data signal is received, it goes through the records to confirm the address and transmits the signal directly to the device whose address matches  the one in the signal. 

8.6.3 Wireless Access Points (WAP)   
In a wireless computer network, a wireless access point (WAP) is a hardware device that allows a Wi-Fi enabled devices such as tablets, laptops, and smartphones to connect to a wired network. 

8.6.4 Router 
It is a device that connects two different networks and sends data signals from one network to another. For example, it can connect a Local Area Network to a Wide Area Network. 
A router performs a routing function. Routing is the process of moving data signals across a network from the source node to the destination node.
A router performs its function by listening to the entire network to determine the best path to route a data signal based on the destination address and the source. 

Figure 8.13: A network using a Wireless Access Point (WAP)


Figure 8.14: A Router 

With Internet connectivity, computers can easily be connected to a network. Networking peripherals refer to hardware equipment, which enables computers to network.  

Examples include hardware such as routers, switches, access points, network interface cards, and other hardware devices.  

Hubs, switches, and routers are all devices that allow computers to be connected to other computers, other network devices, or even other networks. Each of the above peripherals has two or more connectors called ports. In connecting devices, the connecting cables are plugged in through the ports. 

A network peripheral can also be a device that can be connected to a computer in the network either through the ports using data interface cables or using wireless media. Examples are: printers and scanners. 

•Scanners:These are peripheral devices that input data by capturing the data directly from the source to the computer and convert it into a digital format. They are used for making turnaround documents. A turnaround document is a hardcopy output that has been taken back to softcopy for further processing. A scanner in a network can be used by several computers in a network, if it is shared.

•Printers:A printer is an output device that produces hardcopy output usually on a physical print medium such as paper. A printer in a network can serve many computers which submit their print jobs to it. If more than one computer sends a job to the printer at the same time, the submitted jobs are placed in a queue. The jobs in the queue are printed one after the other in the order in which they are admitted in the queue until they are completed.

Figure 8.15: A peer to peer network

8.8 Social Media 

Social media refers to Internet-based applications that enable users to create and exchange information, career interest ideas and other content such as images or videos. They enable people to participate in group networking.

8.8.1 Value of Social Media

The following are some of the values of social media:
• Clarity of information: The information should be clear and easy to understand in order to be very helpful.
• Effectiveness: Only write or talk about something when there is solid evidence that it is true.
• Interesting: One should not be boring. Ensure that the information is engaging and interesting.

• Respectful: One should be careful to be respectful and to appreciate diverse points of view with openness and inclusion. 

8.8.2 Social Media Best Practices 

The following are some of the social media best practices:
• Transparency: Being open builds trust among the social media members. It creates links to connect us with one another by always keeping in touch.
• Be genuine: Be the real person the members would have the pleasure to know.
• Be interested in others: Be a good listener. This shows that one takes an interest in other people.
• Follow back and interact: The interacting members should always be in contact. This creates a healthy goodwill for chatting with each other.
• Do not overshare: Always focus on sharing items that are of value to members.
• Respond to positive and negative comments: Do not only respond to positive comments; pay attention to negative comments as well and respond with maturity. Use good judgement to determine which ones to ignore.
• Keep it short: Some social media platforms, for example, Twitter limit the number of characters in a message Others such as Facebook and Google+ do not have this limit. Strive to keep your messages short.

8.8.3 Examples of Social Media

Some examples of social media include Facebook, Twitter, Google+, LinkedIn, YouTube, Blogging platforms, and Skype among others. 

Facebook 

This is a popular free online social networking website that allows registered users to create profiles, share information such as messages, games, photos and video and keep in touch with friends, family and colleagues.

Figure 8.16: Facebook Logo

Figure 8.17: Logging in to Facebook

Figure 8.18: Log in to Facebook

Twitter This is a free online social networking service that allows registered members to send short messages or short posts referred to as tweets.

Google+

 It is pronounced Google plus. This is a social networking site that is designed by Google to imitate the way people interact offline more closely as compared to other social networking services. It is also used to share other articles on other websites.

 LinkedIn 

This is a social networking site designed for professional networking. It allows registered members to establish and document networks of people they know and trust professionally. To log in to LinkedIn or sign up for an account, search “LinkedIn” on Google, and follow the instructions given.

Figure 8.23(a): LinkedIn Logo

Figure 8.23: Registering a LinkedIn account

YouTube 

This is a free social media site that allows a user to upload, share or watch video content posted from other users.  To log in to YouTube or sign up for an account, search “YouTube”on  Google, and follow the instructions given.

Figure 8.24: YouTube Logo

Figure 8.25: Registering a YouTube account

Blogging 

A blog is a website that contains online personal content such as opinions, reflections, comments and experiences provided by the writer. It usually has images and links to other websites. 

Blogging is the act of posting content on a blog or posting content on another person’s blog. Examples of blogging platforms are Wordpress, Blogspot, Tumblr, Weebly, LiveJournal, and Blogger. 

Skype 

Skype is a social media service that enables file transfers, texting, calling and video conferencing.  It is a service that can be accessed using desktop computers, laptop/notebooks or tablets and other mobile devices, such as mobile phones.

 Figure 8.26: Skype Logo

Figure 8.25: Registering a YouTube account

8.9 Definition of Key Words in this Unit

Revision Exercise 8