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05/03/23 Biya Chaudhry

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Introduction to Computer Networks History of computer networks

Network classification

connection method Wired technologies Wireless technologies Scale Functional relationship (network architecture) Network Topologies

Common Types of Networks Local Area Network (LAN) Wide Area Network (WAN) Metropolitan Area Network (MAN)

Servers

Network Devices Network Interface Cads Switches Hubs Repeaters Routers Bridges

Computer Networks in Society Benefits of Computer Networks Disadvantages of Computer Networks

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Computer network is a set of two or more computers connected together to share information and other resources.

Types of Computers in a Network

Server Computer Terminal Computer

TerminalA server computer is used as a central computer in a network. It controls other computers in a network. It is more powerful than terminals.

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Computer networks can be classified according to the hardware and software technology that is used to interconnect the individual devices in the network, such as optical fiber, Ethernet, wireless LAN, Home PNA, power line communication or G.hn.

Communication devices are directly connected with each other by using some physical media like wires, as,

Twisted pair Coaxial cable Optical fiber cable

Twisted

Fiber Optical

Coaxial

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Different wireless technologies are as follows.

Terrestrial microwave Communications satellites Cellular and PCS systems Wireless LANs Infrared communication

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The network topology defines the way in which computers, printers, and other devices are connected, physically and logically.

Commonly Used Network Topologies are as follows.

Bus Topology Star Topology Ring Topology Tree Topology Mesh Topology

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Following are the main types of computer networks.

It is a computer network that spans a relatively small area. Most LANs are confined to a single building or group of buildings. Most LANs connect workstations and personal computers. Each node in a LAN has its own CPU with which it executes programs, but it also is able to access data and devices anywhere on the LAN.

This means that many users can share expensive devices, such as laser printers, as well as data. Users can also use the LAN to communicate with each other, by sending e-mail or engaging in chat sessions.

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A wide area network (WAN) is a computer network that covers a large geographic area such as a city, country, or spans even intercontinental distances, using a communications channel that combines many types of media such as telephone lines, cables, and air waves. A WAN often uses transmission facilities provided by common carriers, such as telephone companies. Typically, a wide area network (WAN) is generally two LANs connected across a wide geographical area.

It is a large scale network and any network from any area can be its participant. The largest WAN in existence is the Internet. WAN technologies generally function at the lower three layers of the OSI reference model, the physical layer, the data link layer, and the network layer

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MAN is a type of data network designed for a town or city. In terms of geographic breadth, MANs are larger than local-area networks (LANs), but smaller than wide-area networks (WANs). MANs are usually characterized by very high-speed connections using fiber optical cable or other digital media.

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Servers are the work horses of the client/server network. They serve different network users and assist them to accomplish a variety of tasks. The number and types of severs on a client/server network depend on the network size and workload.

Different types of servers are as follows,

Dedicated Server Authentication Sever File Server

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Different devices to connect networks of computers are as follows.

A network card, network adapter, or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network. It provides physical access to a networking medium and often provides a low-level addressing system through the use of MAC addresses.Each network interface card has its unique id. This is written on a chit who is mounted on the card.

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A switch is equipment responsible for undertaking the forwarding and filtering of data based on the Media Access Control (MAC) address of the network cards involved in communication.

This device is similar to a switch, however, it is incapable of filtrating the data packets based on their MAC address, and instead, sends all packets to all devices. It generally has a better performance value on a computer network

A repeater is an electronic device that receives a signal, cleans it of unnecessary noise, regenerates it, and retransmits it at a higher power level, or to the other side of an obstruction, so that the signal can cover longer distances without degradation. In most twisted pair Ethernet configurations, repeaters are required for cable that runs longer than 100 meters. Repeaters work on the Physical Layer of the OSI model. It is used to connect networks of same types to boost the signal.

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A router is the primary device responsible for connecting multiple networks together. It connects the computer to the Internet.

Bridge is a device that connects two or more network segments. It is used to connect Similar types of networks. A bridge reduces network traffic and increases network performance.

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Computer Networks play diverse roles in our Society. Computer Networks have advantages and disadvantages also.

File Sharing Resource Sharing Increased Storage Capacity Increased Cost Efficiency

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Security Issues Rapid Spread of Computer Viruses Expensive Set Up Dependency on the Main File Server

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