Computer network

A collection of computing devices that are connected in various ways in order to communicate and share resources

Usually, the connections between computers in a network are made using physical wires or cables

However, some connections are wireless, using radio waves or infrared signals

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Types of Network

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Local-area network (LAN)A network that connects a

relatively small number of machines in a relatively close geographical area

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The Local Network (LAN)

Client

Client Client

Client Client

Client

Various configurations, called topologies, have been used to administer LANs

Ring topology

A configuration that connects all nodes in a closed loop on which messages travel in one direction

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Star topology A configuration that centers around one node to which all others are connected and through which all messages are sent.

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Bus Topology

All nodes are connected to a single communication line that carries messages in both directions

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Advantages and Disadvantages of Network Topologies

Topology Advantages Disadvantages

Bus Cheap. Easy to install. Difficult to reconfigure.Break in bus disablesentire network.

Star Cheap. Easy to install.Easy to reconfigure.Fault tolerant.

More expensive than bus.

Ring Efficient. Easy to install. Reconfiguration difficult.Very expensive.

Wide-area network (WAN) A network that connects two or more local-area networks over a potentially large geographic distance

Often one particular node on a LAN is set up to serve as a gateway to handle all communication going between that LAN and other networks

Communication between networks is called internetworking

The Internet, as we know it today, is essentially the ultimate wide-area network, spanning the entire globe 15-9

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Metropolitan-area network (MAN) The communication infrastructures that have been developed in and around large cities

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Client and Server computer role in networking Server computer is a core component of

the network, providing a link to the resources necessary to perform any task.

A server computer provides a link to the resources necessary to perform any task.

Client computers normally request and receive information over the network client. Client computers also depends primarily on the central server for processing activities

Computer networks have opened up an entire frontier in the world of computing called the client/server model

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File server A computer that stores and manages files for multiple users on a network

Web server A computer dedicated to responding to requests (from the browser client) for web pages

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Peer-to peer network

A peer-to-peer network is a network where the computers act as both workstations and servers.

great for small, simple, and inexpensive networks.

In a strict peer-to-peer networking setup, every computer is an equal, a peer in the network.

Each machine can have resources that are shared with any other machine.

There is no assigned role for any particular device, and each of the devices usually runs similar software. Any device can and will send requests to any other.

Peer-to peer network (cont..)

Client/Server Networking

In this design, a small number of computers are designated as centralized servers and given the task of providing services to a larger number of user machines called clients

Client/Server Networking (cont..)

Hardware, Software and Networks Peripherals

Network Interface Card (NIC)

RepeaterHubBridgeRoutersSwitch