325: INTRODUCTION TO COMPUTER NETWORKING Meaning and ... · 325: INTRODUCTION TO COMPUTER NETWORKING Meaning and Nature of Information Technology Information technology (IT) is the

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325: INTRODUCTION TO COMPUTER NETWORKING

Meaning and Nature of Information Technology

Information technology (IT) is the use of computers to store, retrieve, transmit, and manipulate data or information, often in the context of a business or other enterprise. IT is considered to be a subset of information and communications technology (ICT). Information and communication technology or (ICT) is extensional term for information technology (IT) that stresses the role of unified communications and the integration of telecommunications (telephone lines and wireless signals), computers as well as necessary enterprise software, middleware, storage, and audio-visual systems, which enable users to access, store, transmit, and manipulate information.

Definition and Importance of Computer Networking

A computer network is a group of systems that are connected to allow the sharing of resources —such as files or printers—or the sharing of services—such as an Internet connection. There are two aspects of setting up a network: the hardware used to connect the systems together and the software installed on the computers that allows them to communicate. The network hardware is made up of two basic components: the entities that want to share the information or resources, such as servers and workstations, and the medium that enables the entities to communicate, which is a cable or a wireless device.

Importance of Computer Networking

a. File Sharing

Computers connected to a network can share files and documents with each other. Personal computers connected to a business network can choose which files and folders are available to share on the network.

b. Printers

Computers can print pages to another computer with a printer on the network. Additionally, printers can be connected using a print server, which allows direct printing from all computers.

c. Sharing Media

Sharing media between computers is easy when connected to a network. Like file sharing, computers can stream musing, videos and movies from one computer to the next.

d. Internet Sharing

Networking enables sharing of Internet services through router, Internet Connection Sharing (ICS) and Wireless Access Point (WAP).

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Networking Topology

A network topology is the physical layout of computers, cables, and other components on a network. There are a number of different network topologies, and a network may be built using multiple topologies. The different types of network layouts are:

a. Bus topology b. Star topology c. Mesh topology d. Ring topology e. Hybrid topology f. Wireless topology

a. Bus Topologies A bus topology uses one cable as a main trunk to connect all of the systems together. A bus topology is easy to set up and requires no additional hardware, such as a hub. The cable is also called a trunk, a backbone, or a segment.

Advantages of a Bus Topology

One advantage of a bus topology is cost. A bus topology uses less cable than a star topology or a mesh topology, and you do not need to purchase any additional devices such as switches.

Disadvantages of a Bus Topology

The main disadvantage of a bus topology is the difficulty in troubleshooting it. When the network goes down, it is usually due to a break in the cable segment. With a large network, this problem can be tough to isolate.

b. Star Topologies

In a star topology, all computers are connected through one central device known as a switch. Each workstation has a cable that goes from the network card to the switch device.

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Advantages of a Star Topology

One advantage of a star topology is scalability and ease of adding another system to the network. If you need to add another workstation to the network with a star topology, you simply connect that system to an unused port on the switch.

Disadvantages of a Star Topology

On the flip side, if the switch fails in a star topology, any devices and downstream switches connected to it are not able to communicate with the rest of the network.

Mesh Topologies

A mesh topology is not very common with computers, but is seen more with networking devices such as routers and switches. In a mesh topology, every device is connected to every other device on the network.

Advantages of a Mesh Topology

The biggest advantage of a mesh topology is fault tolerance, meaning that if there is a break in a cable segment, traffic can be rerouted through a different pathway because there are multiple pathways to send data from one device to another.

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Disadvantages of a Mesh Topology

A disadvantage of a mesh topology is the cost of the additional cabling and network interfaces to create the multiple pathways between each device.

c. Ring Topologies

In a ring topology, all computers are connected via a cable that loops in a ring or circle. A ring topology is a circle that has no start and no end.

Advantages of a Ring Topology

A major advantage of a ring topology is that signal degeneration is low because each workstation is responsible for regenerating the signal.

Disadvantages of a Ring Topology

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Originally, the biggest problem with ring topologies of the past was that if one computer failed or the cable link was broken, the entire network could go down.

d. Hybrid Topologies

It is important to note that it is typical for networks to implement a mixture of topologies to form a hybrid topology. For example, a popular hybrid topology is a star-bus topology, in which a number of star topologies are connected by a central bus.

Wireless Topologies

A wireless topology is one in which only a few cables are used to connect systems. The network is made up of transmitters that broadcast the packets using radio frequencies. The network contains special transmitters called cells, or wireless access points, which extend a radio sphere in the shape of a bubble around the transmitter. This bubble can extend to multiple rooms, and possibly even floors, in a building. The PCs and network devices have a special transmitter-receiver, which allows them to receive broadcasts and transmit requested data back to the access point. The access point is connected to the physical network by a cable, which allows it, and any wireless clients, to communicate with systems on the wired network.

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Advantages of a Wireless Topology

The nice thing about wireless networks is the lack of cabling.

Disadvantages of a Wireless Topology

Disadvantages of wireless networks include a greater chance of signal interference, blockage, and interception.

LANs, WANs, and MANs

A local area network (LAN) typically is confined to a single building, such as an office building, your home network, or a college campus. A wide area network (WAN) spans multiple geographic locations and is typically made up of multiple LANs. For example Ja'iz Bank branch at Zoo Road having 50 computers all connected together would be considered a LAN. If we

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want to allow the branch to share information with one another branch at Rijiyar Zaki, we would connect the two LANs together, creating a WAN. The term metropolitan area network (MAN) refers to a network that exists within a single city—typically multiple buildings in different areas of the city. If we had two different buildings within a city that were separated by city-owned land and were connected together, it would be considered a MAN. You may also hear terms such as CAN, SAN, and PAN. A campus area network (CAN) originated as a network that covers a university campus, but you may find a large organization has a CAN that spans a number of buildings on the company’s private land. A storage area network (SAN) is a high-speed specialized network used to provide storage space to other devices on the network. A personal area network (PAN) is a network created between devices in close proximity, usually within 10 meters, using wireless technology. Another common network acronym we see is WLAN, which stands for wireless LAN. A wireless LAN is a wireless network that is made up of a hotspot created by a wireless access point. You can connect wireless devices such as laptops, tablets, and mobile phones to the wireless network by connecting them to the wireless access point so that they can access resources such as the Internet.

NETWORK TOOLS:

Network tools are the equipment use in setting up a network, it can be programs or hardware (physical component). Among the tools we have punch tool, crimping tools, Rj-45, cable tester etc

NETWORK DEVICES

They are devices that aids connections and communication. The common network devices are ;

a. Hub

b. Network Interface card

c. Switch

d. Router

e. Modem

f. Bridge

a. HUB: Hub is a device that connect all the other devices in a star network together. Every device in the network connect directly to the hub through a single cable. The hub receives a message from a device and broadcast it to all the other devices in the network and monitor it

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for collision to the destination, the hub is not able to identify the device that own the message ( this is the reason why people say the hub is not intelligent).

b. MODEM: Modem is an acronym for modulator/demodulator, it is a device that can convert a digital data to an analog data and vice-verse. Example is a voice band modems that turn the digital data of a personal computer into modulated electrical signal in the voice frequency range of a telephone channels.

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c. SWITCH: Switch is a device that channel incoming data from any of network device to the specific device that is the destination of the data. Unlike the hub, the switch is intelligent because it does not broadcast but channels the data to the specific destination.

d. BRIDGE: Bridge is a device that connect two similar network together. Example is a bridge will connect/join two ring network together or two star network together . It could connect many similar network together.

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e. ROUTER: Router is a network devices that connect two or more dissimilar network together . Example is a router can connect a ring network with a star network, a wireless network and a cable network, a LAN with a WAN etc.

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f. NETWORK INTERFACE CARD (NLC): Network Interface Card is also known as a network interface controller, network adapter, LAN adapter and by similar terms is a computer hardware component that connect a computer to a computer network.

THE INTERNET AND INTRANET.

INTERNET:

The origin of the internet dates back to 1960s when the united states funded research project of its military agencies to build robust, faulty tolerant and distributed computer network. The

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internet is a network that connect different people in different parts of the world. It allows people to communicate and share resources across the globe.

The internet is a global system of interconnected computer network that use the standard internet protocol suite (TCP/IP) to serve billions of users world- wide. It is a network of network that consist of millions of private, public, academic, business and government network of local to global scope that are linked. One of the simplest definitions of internet is that, it is a collection of computer linked together.

INTERNET BROWSER:

A browser is also called a web browser. It is a software application that is used to access and view web pages in the Internet. Some popular browser are; Internet Explorer, Opera, Safari, Chrome, Mozilla firefox, Google, Netscape Navigator etc

BENEFITS/USES OF INTERNET TO THE SOCIETY

Some of the important reason people uses internet are listed below as follows

EDUCATION/E-LEARNING: With the internet, people can get education materials and read them in preparation for exams or use them for school assignment, the internet also enhance electronic learning whereby course or subject are taught online.

E – REGISTRATION: The internet provides users with facilities for online registration for examination like WAEC/NECO and JAMB.

ENTERTAINMENT: The internet kills boredom and enhance leisure by providing its user with latest entertainment in the form of movies, game, news, and many more.

COMMUNICATION: This is one of the key benefit of the internet. The internet provide many means by which user can communicate with friends, family, colleagues, and a lot more through email, chat messenger, facebook etc .

E- BANKING: The internet can be used as a tool to carry out transaction with banks irrespective of users location.

E- COMMERCE: It allows user to buy and sell their good services online.

INTRANET:

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An Intranet is a private network accessible only to an organization’s staff, Intranet that are unavailable to the public unlike the internet. In its simplest form, an intranet is established with the technologies for local area network (LAN) and wide area network (WAN).

When part of an intranet is made accessible to customer and other outside the business, that part becomes part of an extranet. Microsoft sharepoint is the dominant software used for creating collaborating area on intranet.

2.2 BENEFITS/USES OF INTRANET

Some of the important of intranet are listed below as follows;

It used to deliver tool. For example collaboration (to facilitate working in group and teleconferencing).

It is also being used as corporate culture-change platforms. For example, large number of employee discussing key issues in an intranet forum application.

Intranet user-experience, editorial and technology team work together to produce in-house sites. Most commonly, intranet are managed by the communication department of that organization.

MULTIPLEXING AND COMMUNICATION PROTOCOL

MULTIPLEXING:

In telecommunication and computer networks, multiplexing (sometimes contracted to Muxing) is a method by which multiple analog or digital signal are combined into one signal over a shared medium. The aim is to share a scare resource. For example, In telecommunication several telephone call maybe carried using one wire.

The multiplexed signal is transmitted over a communication channels such as a cable. The multiplexing divides the capacity of the communication channels into severals logical channels, one for each message signal or data stream to be transferred. A reverse process known as demultiplexing, extract the original channels on the receiver end.

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Multiple low data rate signal are multiplexed over a single high data rate linked, then demultiplexed at the other end.

A device that perform the multiplexing is called a multiplexer(MUX) and a device that performs the reverse process is called a demultiplexed(DEMUX) or (DMUX). Inverse multiplexing(IMUX) has the opposite aim as multiplexing, namely to break one data stream into several stream, transfer them simultaneously over several communication channels and recreate the original data tream.

TYPE OF MULTIPLEXING

SPACE-DIVISION MULTIPLEXING: Is known as space-division multiple access is the use of separate point-to-point electrical conductor for each transmitted channels, is achieved with multiple antenna element forming a phased array antenna.

FREQUENCY-DIVISION MULTIPLEXING: Frequency-division multiplexing is inherently an analog technology. Frequency-division multiplexing achieves the combining of several signal into one medium by sending signal in several distinct frequency range over a single medium.

TIME-DIVISION MULTIPLEXING: Time-division multiplexing is a digital (or in rare cases, analog) technology which uses time, instead of space or frequency, to separate the different data stream.

POLARIZATION-DIVISION MULTIPLEXING: Polarization-division uses the polarization of electromagnetic radiation to separate orthogonal channels. It is in practical use in both radio and optical communication.

ORBITAL ANGULAR MOMENTUM MULPLEXING: Orbital angular momentum multiplexing is a relatively new and experimental technique for multiplexing multiple channels of signal carried using electromagnetic radiation over a single path.

CODE-DIVISION MULTIPLEXING: Code-division multiplexing, code-division multiplexing access or spread spectrum is a class of technique where several channel simultaneously share the same frequency spectrum, and this spectrum bandwidth is much higher than the bitrate or symbol rate

C

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APPLICATION AREA

Telegraphy

Telephony

Video processing

Digital broadcasting

Analog broadcasting

COMMUNICATION PROTOCOL:

In telecommunication, a communication protocol is a system of rules that allows two or more entities of a communication system to transmit information via any kind of variation of a physical quantity. The protocol defines the rules, syntax, semantics and synchronization of communication and possible error recovery method.

Protocols may be implemented by hardware, software or a combination of both. Communication protocol have to be agreed upon by the parties involved, there is a close analog between protocols and programming language, protocol are to communication then programming language are to computation.

NETWORK MEDIA

Network media is any audio, video, images, or text, used on a computer network, like the internet. It almost always requires a computer to send and receives, as well as a community of people to create and consume the content.

Network media refers to the communication channels used to interconnected nodes on a computer network. Typical example of the network media include copper coaxial cable, copper twisted pair cable and optical fibre cable used in wired network, and radio waves used in wireless data communication network.

TYPE OF NETWORK MEDIA

TWISTED PAIR CABLE:

It can be used for telephone communication and can cable Ethernet network. A pair of wire that can transmit data, there are two type of twisted pair cable which are Unshielded and Shield pair cable.

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COAXIAL CABLE:

It is made of outer hollow conductor and inner wire made of two conducting element, the center of a cable is made of copper wire. Copper wire has surrounding by flexible insulation. Coaxial cable is little expensive than unshielded twisted pair cable, however coaxial cable can be cheaper in physical bus topology.

FIBRE OPTIC CABLE:

It can carry more data in larger distance with light signal than electronic signal carry coaxial cable. Fibre optic can be used medium for telecommunication and network because it is more flexible than other cable. Light transmission through the fibre due to reflection within the materials.