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INTRODUCTION TO COMPUTER NETWORKS

(LAN, MAN & WAN)

Navpreet Singh

Computer CentreIndian Institute of Technology Kanpur

Kanpur INDIA

(Ph : 2597371, Email : navi@iitk.ac.in)

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Content

Content

Introduction to Computer Networks

Physical Media

Overview Of Network Architectures

Campus Networks

Enterprise Networks

Internet

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Computer Networks

Computer network connects two or more autonomous computers.

The computers can be geographically located anywhere.

Introduction to Computer Networks

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LAN, MAN & WAN

Introduction to Computer Networks

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)

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Applications of Networks

Introduction to Computer Networks

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

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

CommunicationEmail, Chat, VoIPMessage broadcast

Remote computing

Distributed processing (GRID Computing)

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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

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QUESTIONS?

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Network Components

Introduction to Computer Networks

Physical Media

Interconnecting Devices

Computers

Networking Software

Applications

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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

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Networking Devices

Introduction to Computer Networks

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

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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

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Networking Protocol: TCP/IP

Introduction to Computer Networks

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Applications

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

Introduction to Computer Networks

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QUESTIONS?

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Physical Media

PHYSICAL MEDIA

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Physical Media

Physical Media

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Physical MediaCopper

Coaxial Cable - Thick or ThinUnshielded Twisted Pair - CAT 3,4,5,5e&6

Optical FiberMultimodeSinglemode

WirelessShort RangeMedium Range (Line of Sight)Satellite

Physical Media

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Copper Media: Coaxial CableCoaxial cable is a copper-cored cable surrounded by a heavy shielding and is used to connect computers in a network.

Outer conductor shields the inner conductor from picking up stray signal from the air.

High bandwidth but lossy channel.

Repeater is used to regenerate the weakened signals.

Physical Media

Category Impedance Use

RG-59RG-59 75 Cable TV

RG-58RG-58 50 Thin Ethernet

RG-11RG-11 50 Thick Ethernet

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Copper Media: Twisted PairTwisted-pair is a type of cabling that is used for telephone communications and most modern Ethernet networks.

A pair of wires forms a circuit that can transmit data. The pairs are twisted to provide protection against crosstalk, the noise generated by adjacent pairs.

There are two basic types, shielded twisted-pair (STP) and unshielded twisted-pair (UTP).

Physical Media

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Unshielded Twisted Pair (UTP)

Physical Media

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Unshielded Twisted Pair (UTP)Consists of 4 pairs (8 wires) of insulated copper wires typically about 1 mm thick.

The wires are twisted together in a helical form.

Twisting reduces the interference between pairs of wires.

High bandwidth and High attenuation channel.

Flexible and cheap cable.

Category rating based on number of twists per inch and the material used

CAT 3, CAT 4, CAT 5, Enhanced CAT 5, CAT 6 and now CAT 6+.

Physical Media

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QUESTIONS?

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Fiber Media

Optical fibers use light to send information through the optical medium.

It uses the principal of total internal reflection.

Modulated light transmissions are used to transmit the signal.

Physical Media

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Total Internal Reflection

Physical Media

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Fiber MediaLight travels through the optical media by the way of total internal reflection.

Modulation scheme used is intensity modulation.

Two types of Fiber media :MultimodeSinglemode

Multimode Fiber can support less bandwidth than Singlemode Fiber.

Singlemode Fiber has a very small core and carry only one beam of light. It can support Gbps data rates over > 100 Km without using repeaters.

Physical Media

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Single and Multimode FiberSingle-mode fiber

Carries light pulses along single pathUses Laser Light Source

Multimode fiberMany pulses of light generated by LED travel at different angles

Physical Media

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Fiber-Optic CableContains one or several glass fibers at its core

Surrounding the fibers is a layer called cladding

Physical Media

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Fiber Optic CableFO Cable may have 1 to over 1000 fibers

Physical Media

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QUESTIONS?

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Wireless MediaVery useful in difficult terrain where cable laying is not possible.

Provides mobility to communication nodes.

Right of way and cable laying costs can be reduced.

Susceptible to rain, atmospheric variations and Objects in transmission path.

Physical Media

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Wireless MediaIndoor : 10 – 50m : BlueTooth, WLAN

Short range Outdoor : 50 – 200m: WLAN

Mid Range Outdoor : 200m – 5 Km : GSM, CDMA, WLAN Point-to-Point, Wi-Max

Long Range Outdoor : 5 Km – 100 Km : Microwave Point-to-Point

Long Distance Communication : Across Continents : Satellite Communication

Physical Media

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Wireless LAN

Physical Media

Internet Router Switch

Access Point

Access Point

PC

PC

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Terrestrial MicrowaveMicrowaves do not follow the curvature of earth

Line-of-Sight transmission

Height allows the signal to travel farther

Two frequencies for two way communication

Repeater is used to increase the distance Hop-by-Hop

Physical Media

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Satellite Communication

Physical Media

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QUESTIONS?