INTRODUCTION TO

COMPUTER NETWORKSCS-107

INTRODUCTION TO COMPUTINGAug-Dec,2010

Alak Roy

Assistant Professor

Dept. of CSE

Royal Group of InstitutionEmail : alakroy.nerist@gmail.com

Computer Networks

Computer network connects two or more autonomous computers.

The computers can be geographically located anywhere.

Introduction to Computer Networks

LAN, MAN & WAN

Network in small geographical Area (Room, Building or a Campus) is called LAN (Local Area Network)

Network in a City is call MAN (Metropolitan Area Network)

Network spread geographically (Country or across Globe) is called WAN (Wide Area Network)

Introduction to Computer Networks

Applications of Networks

Resource SharingHardware (computing resources, disks, printers)Software (application software)

Information SharingEasy accessibility from anywhere (files, databases)Search Capability (WWW)

CommunicationEmailMessage broadcast

Remote computing

Distributed processing (GRID Computing)

Introduction to Computer Networks

Network Topology

The network topology defines the way in which computers, printers, and other devices are connected. A network topology describes the layout of the wire and devices as well as the paths used by data transmissions.

Introduction to Computer Networks

Bus Topology

Commonly referred to as a linear bus, all the devices on a bus topology are connected by one single cable.

Introduction to Computer Networks

Star & Tree TopologyThe star topology is the most commonly used architecture in Ethernet LANs.

When installed, the star topology resembles spokes in a bicycle wheel.

Larger networks use the extended star topology also called tree topology. When used with network devices that filter frames or packets, like bridges, switches, and routers, this topology significantly reduces the traffic on the wires by sending packets only to the wires of the destination host.

Introduction to Computer Networks

Ring TopologyA frame travels around the ring, stopping at each node. If a node wants to transmit data, it adds the data as well as the destination address to the frame.

The frame then continues around the ring until it finds the destination node, which takes the data out of the frame.

Single ring – All the devices on the network share a single cable

Dual ring – The dual ring topology allows data to be sent in both directions.

Introduction to Computer Networks

Mesh Topology

The mesh topology connects all devices (nodes) to each other for redundancy and fault tolerance.

It is used in WANs to interconnect LANs and for mission critical networks like those used by banks and financial institutions.

Implementing the mesh topology is expensive and difficult.

Introduction to Computer Networks

M

Network Components

Physical Media

Interconnecting Devices

Computers

Networking Software

Applications

Introduction to Computer Networks

Networking Media

Networking media can be defined simply as the means by which signals (data) are sent from one computer to another (either by cable or wireless means).

Introduction to Computer Networks

Networking Devices

HUB, Switches, Routers, Wireless Access Points, Modems etc.

Introduction to Computer Networks

Cat 5 cable, RJ45 Connector

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NIC

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activity 10 100

Setting IP address

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Computers: Clients and ServersIn a client/server network arrangement, network services are located in a dedicated computer whose only function is to respond to the requests of clients.

The server contains the file, print, application, security, and other services in a central computer that is continuously available to respond to client requests.

Introduction to Computer Networks

OSI Model – Open System Interconnect

– communicates wit applications- translates, de/compress, de/encrypt- Establishes Connections- Error Correction– Routing, Finding Best Route– disassembles & assembles Data segments– Passes Data onto wire

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7. Application layer

6. Presentation layer

5. Sessions layer

4. Transport layer

3. Network layer

2. Data link layer

1. Physical layer

All People Seem To Need Data ProcessingPlease Do Not Throw Pizza Sausage Away

Developed by ISO & IEEE

Networking Protocol: TCP/IPTransmission control protocol /

internet protocol

Introduction to Computer Networks

TCP, UDP

is a set of rules that enables different types of computers and networks on the Internet to communicate with one.

TCP defines how data are transferred across the Internet to their destination.

IP defines how data are divided into chunks, called packets, for transmission; it also determines the path each packet takes between computers

Applications

E-mailSearchable Data (Web Sites)E-CommerceNews GroupsInternet Telephony (VoIP)Video ConferencingChat GroupsInstant Messengers Internet Radio

Introduction to Computer Networks

www (World Wide Web) or webis a computer-based network of information

resources that combines text and multimedia.

Internet-connected files:a system for accessing, manipulating, and

downloading a very large set of hypertext-linked documents and other files located on computers connected through the Internet

The information on the World Wide Web can be accessed and searched through the Internet, a global computer network.

e-mailelectronic mailelectronic mailmethod of transmitting data, text files,

digital photos, or audio and video files from one computer to another over an intranet or the Internet.

E-mail enables computer users to send messages and data quickly through a local area network or beyond through the Internet. E-mail came into widespread use in the 1990s

and has become a major development in business and personal communications.

ftp (file transfer protocol)standard procedure for transferring files

a standard procedure that allows one computer to transfer files to and from another over a network such as the Internet.

The protocol is a set of rules that ensures a file is transmitted properly to the receiving computer.

A computer that stores files that can be retrieved using FTP is called an FTP site or FTP server.

FTP is part of the Transmission Control Protocol/Internet Protocol (TCP/IP), the system that enables different types of computers and networks on the Internet to communicate.

http (HyperText Transfer Protocol )

protocol for World Wide Webthe client/server protocol : that defines how

messages are formatted and transmitted on the World Wide Web

Example: http://www.gmail.com

URL (Uniform Resource Locator), an address that points to a particular document or other resource on the Internet, used most frequently on the World Wide Web (WWW).

The first part of the URL, the part before the colon, represents the scheme, or protocol, used to retrieve the document.

In this case, http indicates that the document is a Web page viewable by a Web browser.

rloginRemote login

–is one of the advantage of desktop sharingUses desktop sharing software to give you

‘remote control’ for accessing your computer and all of its software and hard drive files from any internet connected device anywhere in the world.

Thank You