Hardware Components of Computer Network

Hardware Components

Physical parts and devices used to connect computers in the network environment are called hardware components.

The hardware components of a network are:

Server

Workstation

Connectors

Cables

NIC

Hub

Repeater

Bridge

Switch

Router

Gateway

MODEM

Server

Server is the main computer that provides services, data and other resources to other computers in the network environment.

The server computer uses networking operating software like Novell Netware Server, Windows NT Server, Linux, UNIX, etc.

Different types of servers are file server, print server, application server etc.

The differences between Dedicated Server and Non-dedicated Server are:

Dedicated Server	Non-dedicated Server
A server computer that controls and provides services hardware and software resources to other computers on the network is called dedicated server.	A computer on a network that allows a user to use it as a workstation and provides facilities of sharing its resources to other computers on the network is called non-dedicated server.
It controls and provides resources to the client computers on the network but does not allow a user to use it as a workstation.	It controls and provides resources to the other computers on the network as well as allows a user to use it as a workstation.

WorkstationWorkstation is a computer, where the client works which requests services, data and other resources available on the server.

The client computer uses operating system like Windows 98, Windows XP,  Red Hat Linux Workstation,etc.

Node

Each computer or device in a network is called node.

CablesCables are commonly used mediums for physical channel for transmitting data across network.

Examples of cables are coaxial, twisted pair and fiber optic cable.

NIC

A Network Interface Card (NIC) is a hardware device that acts as an interface through which a computer is connected to a network.

The function of NIC is to convert data into electronic signals and transfer them through cables and vice-versa.

ConnectorsConnectors acts as an interface between the NIC of the computer and the cable that passes data from one computer to another.

Examples of connectors are BNC used with coaxial cable, RJ 45 used with UTP cable, ST used with fiber optic cable etc.

Hub

A hub is a network device with multiple points or ports which acts as a central point from where different computers and other devices are connected.

Hub is mostly used in physical star topology.

It cannot determine source and destination device of the data. 

Hub broadcasts the electric signals

Switch

A switch is a networking device that has multiple connecting ports which is often used interchangeably with the bridge.

It can determine source and destination device of data.

RepeaterRepeater is a device that amplifies the incoming signals, creates a copy of it and transmits the signals on network.

Bridge

A bridge is a device that connects two or more similar types of network which filters the data or inspects incoming signals and decides whether to forward the signals or discard them.

Router

Router is an intelligent device that connects two different networks which uses the address for filtering and forwarding the data as well as it has an ability to determine the best route for destination.

Gateway

Gateway is an interconnecting device that connects two dissimilar networks.

MODEM

MODEM is a device which is used to transfer the data of one computer to another computer using telephone lines.

The role of MODEM in data transmission is that it transfers data from one computer to another through telephone line. It also converts the digital signal into analog and vice versa.

Modulation

The process of translating digital signals of a computer to analog signals, which are then transmitted across the standard telephone lines, is known as modulation.

Demodulation

The process of translating analog signals from a phone line and converts then into digital signals for the computer is known as demodulation.

How does MODEM help in transmission of data in computer network?

MODEM helps in transmission of data in computer network by transferring the data of one computer to another using a telephone line. It converts the discrete stream of digital ON-OFF electrical pulses used by computers into the continuously variable analog wave patterns over existing telephone lines and vice versa.

Mention the importance of MODEM in computer network.

The importance of MODEM in computer network is that it enables a computer to transmit data and files over a telephone line. It can convert digital signals into analog signals and vice-versa.

Modes of Transmission and its types [Simplex, Half Duplex and Full Duplex]

CommunicationCommunication means sending and receiving information between two or more persons.

TelecommunicationTelecommunication is a system of transmission of sounds, images, texts or data in the form of electronic signals.

Data communication

A data communication system is the collection of hardware, software and other devices that allows to exchange data, information and voice between two or more devices through a wire or radio waves.

The components of data communication are data, sender, medium, receiver and protocol.

Any two examples of data communication are e-mail and chat

Data transmission mode

Data transmission mode is the way of transmitting data from one device to another.

The modes of data transmission are simplex mode, half duplex mode, full duplex mode

Simplex mode

The mode of transmission where transmission can take place in only one direction is called simplex mode.

Examples of simplex mode are TV Broadcasting, Radio transmission and Newspaper.

Half-duplex mode

The mode of transmission where data can be transmitted to both directions, but only to one direction at a time is called half-duplex mode.

Examples of half-duplex mode are Wireless handset and Walky-talky

Full-duplex mode

The mode of transmission which allows simultaneous transmission of data to both directions is called full-duplex mode.
Example of full-duplex mode is telephone

BandwidthBandwidth can be defined as the maximum volume of data that can be transmitted through the communication medium.

We can measure bandwidth in digital devices by bits per second and in analogue devices by cycles per second or Hertz (Hz).

Transmission Media and Its Types [Guided and Unguided Media]

Transmission Media

}  Transmission medium is a channel through which data or signals can be transmitted from sender to receiver.

}  Data is transmitted through the electromagnetic signals.

}  Transmission media are also called communication channels.

Guided Media

}  It is a wired transmission media, in which data signals are guided along a physical path i.e. within a wire. 

}  Also known as Bounded or wired media.

}  Examples are Twisted Pair Cable, Coaxial cable and fiber optic cable.

Twisted Pair Cable

}  A pair of wires which are made of copper and are twisted with each other is known as twisted pair cable.

}  A set of four pairs of twisted wires are bundled to form cable.

}  The wires are twisted to reduce cross talk and electrical interference.

}  It was invented by Alexander Graham Bell in 1881.

}  Its types are :

◦      Unshielded Twisted Pair Cable (UTP)

◦      Shielded Twisted Pair Cable (STP)

Unshielded Twisted Pair Cable (UTP)

}  The unshielded twisted pair cable is a Guided Transmission Media, which is used for transmitting both data and voice. 

}  It consists of 4 pairs of colour-coded wires twisted around each other.

}  The wires are twisted to prevent electromagnetic interference (cross talk)

}  Cat 5 cable with RJ-45 connector is commonly used with unshielded twisted pair

Shielded Twisted Pair Cable (STP)

}  The shielded twisted pair cable is a Guided Transmission Media , which is quite expensive than unshielded twisted pair cable.  

}  It has a foil shield that covers the wires.

}  The foil shield adds a layer of protection against electro-magnetic interference leaking into and out of the cable.

}  Shielded Twisted Pair Cable are more expensive than Unshielded Twisted Pair Cable, but less susceptible to noise.

Co-axial Cable

}  A cable which is used with single ended single reference where the central conductor carries the data signal is called co-axial cable.

}  The connectors used with co-axial cables are BNC, T-connectors and terminators in bus topology.

}  10 Mbps is the maximum speed of co-axial cable.

}  Coaxial cable is used in cable television.

}  It is preferred for long distance telephone lines as well.

Fiber Optic Cable

}  Fiber optics cable is one of the costlier cables used in data communication which uses light to carry a data signal through the cable.

}  The connectors used in fiber optics are Screw Mounted Adaptors (SMA), Spring-loaded Twist (ST), SC and FC.

}  It is costlier to maintain, produce and install.  

}  Fiber-optic cable do not get affected by electromagnetic interference.

}  Works for both analog as well as digital signals.

}  Point to point one way communication generally uses the cable.

Unguided Media

}  Unbounded media are wireless media that does not require any physical medium to transmit electromagnetic signals. 

}  The electromagnetic signals are broadcasted through air to everyone instead of cables.

}  e.g.: radio waves, micro waves and infrared waves.

Radio Wave

}  It is a form of wireless communications in which signals are sent through radio frequency waves.

}  It provides low bandwidth for data communication.

}  The radio waves are generated easily; they are low-frequency signals and can travel a long distance.

}  The radio waves can penetrate through the buildings.

}  Frequency Range:3KHz – 1GHz.

}  AM and FM radios and cordless phones use Radiowaves for transmission.

Microwave

}  It is a form of wireless communication in which data signals are sent through pulses of electromagnetic energy.

}  The microwave has a frequency higher than the radio waves.

}  The microwaves are transmitted in a straight line and hence require the line-of-sight transmission. 

}  More the taller are antennas longer is the distance covered by the signal.

}  Frequency Range:1GHz – 300GHz. 

}  Microwave are used for telephone communication mobile phones, television distribution, etc.

Infrared

}  Infrared waves are used for short range communication.

}  Like, the remote control for televisions, VCRs, wireless mouse, keyboard, printer, etc. uses infrared waves.

}  It can not penetrate (enter) through obstacles. 

}  Frequency Range:300GHz – 400THz.

Definition of Computer Network and Advantages and Disadvantages of Computer Network

Computer Network

A computer network is a group of interconnected computers through transmission media in order to communicate, share data, information, hardware and software resources.

Advantages of  Computer Network

1. Computer in a network can access the network-connected hardware devices like printers, disk drives, etc.
2. Data in a network environment can be updated from any computer. Updated data can be accessed by all computers on the network.
3. Computers in a network system share different software packages.
4. Information can be exchanged rapidly in computer network.

Disadvantages of  Computer Network

1. The sharing of information may leak the privacy of other clients.
2. If any computer system in a network gets affected by computer virus, there is a big chance of spreading computer viruses on other computers on the network.
3. Computers on the network have to depend on the server computer for the resources.
4. Data and information may be stolen by computer hackers if the security of network is not reliable.

Mention the reasons of keeping computers on the network.

The reasons of keeping computers on the network are

1. To share hardware devices like printers, scanners, hard disks etc.
2. To share data and information.
3. to share software resources.
4. To communicate with each other.

List the main goals of computer network.

The main goals of computer network are

1. Resource sharing
2. Reliability
3. Communication medium
4. Access to remote database
5. Easy data transfer

Computer Network reduces expenses of an office. Justify this statement with suitable examples.

Computer network reduces expenses of an office. It is because in offices, there may be more than one computer and they may need to produce hard copy outputs, scan documents and send faxes. But it is impractical for each individual computer of an office to have expensive computer hardware like laser printer, scanner, fax machine etc. So, to reduce the expenses, computers are kept on the network.

Computer network makes the world a small place. Justify this statement with strong reasons.

Computer network makes the world a small place. Because of computer network, it is easy for the average person using his/her PC to make reservation for airplanes, trains, hotels, check bank balance in account and transfer money from banks and so on anywhere in the world with instant confirmation. The server computer on the network acts as the storehouse and distributor for the data, information and programs.