Computer Network Assignment A134727 & A134662

Introduction
A computer network, often simply referred to as a network, is a group of computers and devices interconnected by communications channels that facilitate communications among users and allows users to share resources. Networks may be classified according to a wide variety of characteristics.

A computer network allows sharing of resources and information among interconnected devices. In the 1960s, the Advanced Research Projects Agency (ARPA) started funding the design of the Advanced Research Projects Agency Network (ARPANET) for the United States Department of Defense. It was the first computer network in the world.[1] Development of the network began in 1969, based on designs developed during the 1960s.

BACKGROUND

'''Before the advent of computer networks that were based upon some type of telecommunications system, communication between calculation machines and early computers was performed by human users by carrying instructions between them. Many of the social behaviors seen in today's Internet were demonstrably present in the nineteenth century and arguably in even earlier networks using visual signals.'''

'''In September 1940 George Stibitz used a teletype machine to send instructions for a problem set from his Model at Dartmouth College in New Hampshire to his Complex Number Calculator in New York and received results back by the same means. Linking output systems like teletypes to computers was an interest at the Advanced Research Projects Agency (ARPA) when, in 1962, J.C.R. Licklider was hired and developed a working group he called the "Intergalactic Network"Bold text, a precursor to the ARPANet.'''

'''In 1964, researchers at Dartmouth developed the Dartmouth Time Sharing System for distributed users of large computer systems. The same year, at MIT, a research group supported by General Electric and Bell Labs used a computer DEC's to route and manage telephone connections.'''

Throughout the 1960s Leonard Kleinrock, Paul Baran and Donald Davies independently conceptualized and developed network systems which used datagrams or packets that could be used in a network between computer systems.

1965 Thomas Merrill and Lawrence G. Roberts created the first wide area network (WAN).

The first widely used PSTN switch that used true computer control was the Western Electric introduced in 1965.

'''In 1969 the University of California at Los Angeles, SRI (in Stanford), University of California at Santa Barbara, and the University of Utah were connected as the beginning of the ARPANET network using 50 kbit/s circuits. Commercial services using X.25 were deployed in 1972, and later used as an underlying infrastructure for expanding TCP/IP networks.'''

'''Computer networks, and the technologies needed to connect and communicate through and between them, continue to drive computer hardware, software, and peripherals industries. This expansion is mirrored by growth in the numbers and types of users of networks from the researcher to the home user.'''

'''Today, computer networks are the core of modern communication. All modern aspects of the Public Switched Telephone Network (PSTN) are computer-controlled, and telephony increasingly runs over the Internet Protocol, although not necessarily the public Internet. The scope of communication has increased significantly in the past decade, and this boom in communications would not have been possible without the progressively advancing computer network.'''

BENEFITs

Computer networks can be used for several purposes:
 * Facilitating communications. Using a network, people can communicate efficiently and easily via email, instant messaging, chat rooms, telephone, video telephone calls, and video conferencing.
 * Sharing hardware. In a networked environment, each computer on a network may access and use hardware resources on the network, such as printing a document on a shared network printer.
 * Sharing files, data, and information. In a network environment, authorized user may access data and information stored on other computers on the network. The capability of providing access to data and information on shared storage devices is an important feature of many networks.
 * Sharing software. Users connected to a network may run application programs on remote computers.

'NETWORK CLASSIFICATIONS'

Computer networks can be classified by means of a lot of types like the network size, structure, mode of connectivity, topology and others. Some of them are, 

Network Size Considering the size of the implemented network, Computer networks are classified into 3 main divisions namely Local Area Network (LAN), Wide Area Network (WAN) and Metropolitan Area Network (MAN). In certain fields, they are also further classified into Personal Area Network (PAN), Campus Area Network (CAN) and Global Area Network (GAN). '''

LAN: - A network of computers which cover only a small area like an office or a building can be referred to as a Local Area Network. All the individual computers must have a common protocol layer for their connectivity with the basic functionality taking place at the network layer. In general, LANs are based on Ethernet technology. '''

WAN: - Wide Area Network is basically an extension of the Local Area Network except for the fact that the size of the network extends to a very large area. The major functionality of the WAN networks take place at the 3 lower layers of the OSI model namely network layer, data link layer and the physical layer. '''

MAN: - Metropolitan Area network is a combination of two or more individual Local Area Networks but with a small criterion of the boundary of the network not exceeding the city limits, thus integrating the network as a single unit within a city. '''

PAN: - Personal network is the smallest of all networks with most of the networks not exceeding a total size of 25 feet. '''

CAN: - This is similar to a wide area network but the size of the network is limited to a certain social limit, for example the network in an university where the total network is formed by the collaboration of more than one Local Area Network. '''

GAN: - Global Area Networks are large scale WANs and are implemented globally. The total network consists of a large number of sub-networks with most of the connectivity between the networks is done using wireless networks. '''

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Structure Of The Network Considering the structure and relationship between the elements of a computer network, the network may be classified into 3 divisions namely Client-Server model, Peer to Peer model and Active Networking model. Each of the classifications has a separate and unique structure which differentiates them in connectivity and working mode. '''

Mode of Connectivity By means of the connection mechanisms, computer networks are divided into wired networks and wireless networks. The wired networks are further divided into some sub-divisions like Optical Fiber and Ethernet networks. '''

Topology In general, a computer network is technically classified based on the topology of the total network which includes the structure of the networks too. They are divided into Bus networks, Ring network, Star network, Mesh network, Star-bus network, Tree network. '''

Hardware Requirements for a Network Set-Up Other than the computers required for a network establishment, the requirement arises for other hardware components too. Some of them are, '''

Routers Routers simply function as an intermediary device which forwards the data packets that it receives, to the next available or neighboring router or a terminal. '''

Switches Switches are the virtual controllers of routers and bridges. These are operated from each of the individual layers of the OSI layer. Certain cases where the devices operate on multiple layers are called multilayer switch. '''

Bridges Technically, a bridge acts a connector between the data link layer and the network layer. The three types of bridges are Local Bridges, Remote Bridges and Wireless bridges. '''

Network Cards Network cards are the most important hardware component of a computer network. The most important functionality of the layer is to enable communication between the computers in a network. '''

Basic hardware components

Hardware comprises all of the physical part of the computer such as Monitor, CPU, motherboard, ram, CD-Rom, printer, scanner, hard disk, flash drive (AKA pen drive), processor, pci buses, floppy disk, power supply, VGA card, sound card, network interface card, peripherals, joystick, mouse, keyboard, foot pedal, computer fan, camera, headset and others.

On the other hard software is a logical part of a computer and is used to carry out the instructions, storing, executing and developing other software programs. A typical PC consists of a case or chassis in the desktop or tower case and these components.

Motherboard • CPU • Computer Fan • RAM • BIOS • Digital Circuitry • Computer Fan • PCI Slots