Introduction Introduction to to

Computer AdministrationComputer Administration

Computer Network - Computer Network - Basic ConceptsBasic Concepts

Computer NetworksComputer Networks Communication ModelCommunication Model Transmission ModesTransmission Modes Communication TypesCommunication Types Classification Of Computer Networks Classification Of Computer Networks

By ScaleBy Scale By StructureBy Structure By TopologyBy Topology

Network MediaNetwork Media InternetworkingInternetworking

Computer NetworkComputer Network A computer network is a group of A computer network is a group of interconnected computers.interconnected computers.

It allows computers to communicate with each It allows computers to communicate with each other and to share resources and information. other and to share resources and information.

First Network : The Advanced Research Projects First Network : The Advanced Research Projects Agency (ARPA) funded the design of the Agency (ARPA) funded the design of the "Advanced Research Projects Agency Network" "Advanced Research Projects Agency Network" (ARPANET) for the United States Department of (ARPANET) for the United States Department of DefenseDefense

Communication ModelCommunication Model

Communication ModelCommunication Model SourceSource

generates data to be transmittedgenerates data to be transmitted TransmitterTransmitter

Converts data into transmittable signalsConverts data into transmittable signals Transmission SystemTransmission System

Carries dataCarries data ReceiverReceiver

Converts received signal into dataConverts received signal into data DestinationDestination

Takes incoming dataTakes incoming data

Communication ModelCommunication Model

Transmission ModesTransmission Modes SimplexSimplex

One directionOne direction e.g. Televisione.g. Television

Half duplexHalf duplex Either direction, Either direction, but only one way but only one way at a timeat a time

e.g. police radioe.g. police radio

Full duplexFull duplex Both directions at Both directions at the same timethe same time

e.g. telephonee.g. telephone

Communication TypesCommunication Types Unicasting (one-to-one)Unicasting (one-to-one)

Multicasting (one-to-many)Multicasting (one-to-many)

Broadcasting (one-to-all)Broadcasting (one-to-all)

Network ClassificationNetwork Classification By Size or ScaleBy Size or Scale

LANLAN WANWAN MANMAN CANCAN PANPAN

Local Area Network (LAN)Local Area Network (LAN) Contains printers, servers and Contains printers, servers and computerscomputers

Systems are close to each otherSystems are close to each other Contained in one office or Contained in one office or buildingbuilding

Organizations often have Organizations often have several LANSseveral LANS

Wide Area Networks (WAN)Wide Area Networks (WAN) Two or more LANs connectedTwo or more LANs connected Over a large geographic areaOver a large geographic area Typically use public or leased Typically use public or leased lineslines Phone linesPhone lines SatelliteSatellite

The Internet is a WANThe Internet is a WAN

Metropolitan Area Network Metropolitan Area Network (MAN)(MAN)

Large network that connects Large network that connects different organizationsdifferent organizations

Shares regional resourcesShares regional resources A network provider sells timeA network provider sells time

Campus Area Networks Campus Area Networks (CAN)(CAN)

A LAN in one large geographic A LAN in one large geographic areaarea

Resources related to the same Resources related to the same organizationorganization

Each department shares the LANEach department shares the LAN

Personal Area Network Personal Area Network (PAN)(PAN)

Very small scale networkVery small scale network Range is less than 2 metersRange is less than 2 meters Cell phones, PDAs, MP3 playersCell phones, PDAs, MP3 players

Network ClassificationNetwork Classification By Structure / Functional By Structure / Functional RelationshipRelationship Client / ServerClient / Server Peer to Peer (P2PN)Peer to Peer (P2PN)

Client/Server networkClient/Server network Nodes and servers share data rolesNodes and servers share data roles Nodes are called clientsNodes are called clients Servers are used to control accessServers are used to control access Database softwareDatabase software

Access to data controlled by serverAccess to data controlled by server Server is the most important Server is the most important computercomputer

Peer to peer networks Peer to peer networks (P2PN)(P2PN)

All nodes are equalAll nodes are equal Nodes access resources on other Nodes access resources on other nodesnodes

Each node controls its own Each node controls its own resourcesresources

Most modern OS allow P2PNMost modern OS allow P2PN Distributed computing is a formDistributed computing is a form KazaaKazaa

Network ClassificationNetwork Classification By Topology / Physical By Topology / Physical ConnectivityConnectivity BUSBUS STARSTAR RINGRING MESHMESH TREETREE

Network TopologyNetwork Topology Logical layout of wires and Logical layout of wires and equipmentequipment

Choice affects Choice affects Network performanceNetwork performance Network sizeNetwork size Network collision detectionNetwork collision detection

BUSBUS Also called linear busAlso called linear bus

One wire connects all One wire connects all nodesnodes

Terminator ends the wiresTerminator ends the wires

AdvantagesAdvantages Easy to setupEasy to setup Small amount of wireSmall amount of wire

DisadvantagesDisadvantages SlowSlow Easy to crashEasy to crash

STARSTAR All nodes connect to a hubAll nodes connect to a hub

Packets sent to hubPackets sent to hub Hub sends packet to destinationHub sends packet to destination

AdvantagesAdvantages Easy to setupEasy to setup One cable can not crash networkOne cable can not crash network

DisadvantagesDisadvantages One hub crashing downs entire One hub crashing downs entire networknetwork

Uses lots of cableUses lots of cable

Most common topologyMost common topology

RINGRING Nodes connected in a circleNodes connected in a circle

Tokens used to transmit dataTokens used to transmit data Nodes must wait for token to sendNodes must wait for token to send

AdvantagesAdvantages Time to send data is knownTime to send data is known No data collisionsNo data collisions

DisadvantagesDisadvantages SlowSlow Lots of cableLots of cable

MESHMESH All computers connected All computers connected

togethertogether

Internet is a mesh networkInternet is a mesh network

AdvantageAdvantage Data will always be Data will always be delivereddelivered

DisadvantagesDisadvantages Lots of cableLots of cable Hard to setupHard to setup

TREETREE Hierarchal ModelHierarchal Model

AdvantagesAdvantages ScaleableScaleable Easy ImplementationEasy Implementation Easy TroubleshootingEasy Troubleshooting

Network MediaNetwork Media Links that connect nodesLinks that connect nodes Choice impactsChoice impacts

SpeedSpeed SecuritySecurity SizeSize

Twisted-pair cablingTwisted-pair cabling Most common LAN cableMost common LAN cable

Called Cat5 or 100BaseTCalled Cat5 or 100BaseT

Four pairs of copper cable Four pairs of copper cable twistedtwisted

May be shielded from May be shielded from interferenceinterference

Speeds range from Speeds range from 1 Mbps to 1,000 Mbps1 Mbps to 1,000 Mbps

Coaxial cableCoaxial cable Similar to cable TV wireSimilar to cable TV wire

One wire runs through cableOne wire runs through cable

Shielded from interferenceShielded from interference

Speeds up to 10 MbpsSpeeds up to 10 Mbps

Nearly obsoleteNearly obsolete

Fiber-optic cableFiber-optic cable Data is transmitted with Data is transmitted with

light pulseslight pulses

Glass strand instead of cableGlass strand instead of cable

Immune to interferenceImmune to interference

Very secureVery secure

Hard to work withHard to work with

Speeds up toSpeeds up to100 Gbps100 Gbps

Wireless MediaWireless Media Data transmitted through the airData transmitted through the air

LANs use radio wavesLANs use radio waves

WANs use microwave signalsWANs use microwave signals

Easy to setupEasy to setup

Difficult to secureDifficult to secure

Internetwork An Internetwork is the connection of two or more distinct computer networks or network segments via a common routing technology.

Any interconnection among or between public, private, commercial, industrial, or governmental networks may also be defined as an internetwork.

InternetworkInternetwork Intranet

An intranet is a set of networks, using the Internet Protocol and IP-based tools such as web browsers and file transfer applications, that is under the control of a single administrative entity.

Most commonly, an intranet is the internal network of an organization Extranet

An extranet is a network or internetwork that is limited in scope to a single organization or entity but which also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities

by definition, an extranet cannot consist of a single LAN; it must have at least one connection with an external network.

Internet The Internet consists of a worldwide interconnection of governmental,

academic, public, and private networks based upon the networking technologies of the Internet Protocol Suite.

It is the successor of the Advanced Research Projects Agency Network (ARPANET) developed by DARPA of the U.S. Department of Defense.

The Internet is also the communications backbone underlying the World Wide Web (WWW).