computer networking fundamental - ec301 1

8/11/2019 Computer Networking Fundamental - EC301 1

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Computer Networking

Fundamental EC301Introduction to Networking


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Introduction to Networking

Basic concepts and components ofcomputer networks

Basic concepts and components ofcomputer networks

Networking Standards

Networking Standards

Principles of communication innetworking

Principles of communication innetworking

Functions of Networking ardware

Functions of Networking ardware


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!"at is a

network#

!"$ we usenetwork#


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Network de%nition

& com'ination of computer "ardware(ca'ling( network de)ices( andcomputer software used toget"er toallow computers to communicatewit" eac" ot"er*

+roup of computers and ot"erde)ices t"at are connected '$ somet$pe of transmission media*


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/"e ad)antages of networked computing

relati)e to standalone computing*

Fewer Perip"erals Needed an$ de)ices can 'e connected on a

network*

Increased Communication Capa'ilities Networks pro)ide se)eral di-erent

colla'oration tools t"at can 'e used tocommunicate 'etween network users*

&)oid File uplication and Corruption & ser)er manages network resources*

Ser)ers store data and s"are it wit" users ona network*


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/"e ad)antages of networked computing

relati)e to standalone computing* 2ower Cost 2icensing

&pplication licensing can 'e epensi)e forindi)idual computers*

Centrali4ed &dministration Centrali4ed administration reduces t"e

num'er of people needed to manage t"ede)ices and data on t"e network(reducing time and cost to t"e compan$*

Conser)e 5esources ata processing can 'e distri'uted across

man$ computers to pre)ent onecomputer from 'ecoming o)erloaded wit"processing tasks*


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Fundamental t$pes of networks

Peer.to.peer networks

Client6ser)ernetworks
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E)er$ computer can communicatedirectl$ wit" e)er$ ot"er computer

B$ default( no computer "as more

aut"orit$ t"an anot"er E)er$ computer is capa'le of sending

and recei)ing information to andfrom e)er$ ot"er computer


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&d)antages of a peer.to.peernetwork7 2ess initial epense . No need for a

dedicated ser)er*

Setup . &n operating s$stem 8suc" as!indows 9P: alread$ in place ma$ onl$need to 'e recon%gured for peer.to.peeroperations*

isad)antages of a peer.to.peernetwork7 ecentrali4ed . No central repositor$ for

%les and applications*

Securit$ . oes not pro)ide t"e securit$

a)aila'le on a client6ser)er network*


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Client6ser)er networks

Ser)er central computer used to facilitate

communication and resource s"aring'etween ot"er computers on t"e network

8called clients: Client6ser)er network

uses a ser)er to ena'le clients to s"are data(data storage space( and de)ices

/o function as a ser)er( a computer must'e running a network operating s$stem8N;S:

ost of t"e concepts on t"e Networkce*

,suall$ spans a'out 0.?kms and is generall$a pri)ate network owned '$ an organi4ation*

Eac" computer "as t"e potential tocommunicate wit" an$ ot"er computer oft"e network*

ig" degree of interconnection 'etweencomputers

Eas$ p"$sical connection of computers in anetwork*

Inepensi)e medium of data transmission*

ig" data transmission rate*


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2ocal area network 82&N:


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etropolitan &rea Network

2arger t"an a 2&N@ connects clientsand ser)ers from multiple 'uildings

Is used to descri'e a network of

computers spanning a metropolitancit$ usuall$ ?.?0 kms of range*

& compan$ "a)ing multiple o>ces in)arious parts of a cit$ generall$ usest"is t$pe of network*

Eample is t"e cellular or mo'ilep"one network*


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etropolitan &rea Network


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!ide area network 8!&N:

Connects two or more geograp"icall$distinct 2&Ns or &Ns

Communication facilit$

5emote data entr$

Centralised information

/"e transmission medium used isnormall$ telep"one lines( microwa)es

and satellite links* Internet is an eample of a wan


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!ide area network 8!&N:


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The diferences between LANand WAN

LAN 5estricted to limitedgeograp"ical area offew kilometres

e)ices are connectedwit" wires and coaial

ca'les Cost of data

transmission in 2&N isless

/"e speed of data

transmission is muc""ig"er in 2&N t"an in!&N* /"e speed )ariesfrom 0*1 to 100 m'ps

Few data transmissionerrors occur in 2&N

compared to !&N*

WAN Co)ers long distanceand operatesnationwide or e)enworldwide

Communication is done

t"roug" telep"one linesand satellite links

Cost of datatransmission is )er$"ig"

!&N t"e speed rangesfrom 1A00 to 00 'ps*

ore data transmissionerrors occur in !&Ncompared to 2&N*


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ElementsCommon toClient/Serv

erNetworks

!orkstation!orkstationNetwork Interface

Card 8NIC:

Network InterfaceCard 8NIC:

Network;perating

S$stem 8N;S:

Network;perating

S$stem 8N;S:

Connecti)it$de)ice

Connecti)it$de)ice

/ransmissionedia

/ransmissionedia

/opolog$/opolog$

SegmentSegment

ostost

NodeNode

Ser)erSer)er

ClientClient


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Ser)er

& computer on t"e network t"atmanages s"ared resources@ ser)ersusuall$ "a)e more processing power(memor$( and "ard disk space t"anclients*

/"e$ run network operating softwaret"at can manage not onl$ data( 'utalso users( groups( securit$( and

applications on t"e network*


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Client

& computer on t"e network t"atre=uests resources or ser)ices fromanot"er computer on a network@ insome cases( a client could also act asa ser)er*

/"e term client ma$ also refer to t"e"uman user of a client workstation orto client software installed on t"e

workstation*


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!orkstation

& personal computer 8suc" as adesktop or laptop:( w"ic" ma$ orma$ not 'e connected to a network@most clients are workstationcomputers*


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ost

& computer t"at ena'les resources"aring '$ ot"er computers on t"esame network


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Node

& client( ser)er( or ot"er de)ice t"atcan communicate o)er a network andt"at is identi%ed '$ a uni=ue num'er(known as its network address*


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Segment

& part of a network*

,suall$( a segment is composed of agroup of nodes t"at use t"e samecommunications c"annel for all t"eirtra>c*


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Connecti)it$ e)ice

& speciali4ed de)ice t"at allowsmultiple networks or multiple parts ofone network to connect andec"ange data*

& client6ser)er network can operatewit"out connecti)it$ de)ices*

owe)er( medium. and large.si4ed2&Ns use t"em to etend t"e network

and to connect wit" !&Ns*


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/opolog$

/"e p"$sical la$out of a computernetwork*

/opologies )ar$ according to t"eneeds of t"e organi4ation anda)aila'le "ardware and epertise*

Networks can 'e arranged in a ring('us( or star formation( and t"e starformation is t"e most common*

$'rid com'inations of t"esepatterns are also possi'le*


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/ransmission edia

/"e means t"roug" w"ic" data istransmitted and recei)ed*

/ransmission media ma$ 'e p"$sical(suc" as wire or ca'le( or atmosp"eric8wireless:( suc" as radio wa)es*


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Network Interface Card

/"e de)ice inside a computer t"atconnects a computer to t"e networkmedia( t"us allowing it tocommunicate wit" ot"er computers@

Some connect to t"e mot"er'oard(w"ic" is t"e main circuit t"at controlst"e computer( some are integratedas part of t"e mot"er'oard( and

ot"ers connect )ia an eternal port* NICs are also known as network

adapters*


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Network ;perating S$stem

/"e software t"at runs on a ser)erand ena'les t"e ser)er to managedata( users( groups( securit$(applications( and ot"er networking

functions* Eamples include )arious t$pes of

,NI9 and 2inu operating s$stems(icrosoft !indows Ser)er D003 or

!indows Ser)er D00A( and ac ;S 9Ser)er*


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Network /opolog$

Bus

5ing

Star

$'rid Star !ired Bus

Star !ired 5ing


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Bus

In 'us topolog$ all workstations areconnected to a single communicationline called 'us*

In t"is t$pe of network topolog$ t"ereis no central ser)er and all t"ecomputers can talk or communicateto all ot"er s$stems connected to t"eca'le*

/ransmission from an$ station tra)elst"e lengt" of t"e 'us in 'ot"directions and can 'e recei)ed '$ allworkstations*


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5ing

In ring topolog$ eac" station isattac"ed to near'$ stations on apoint.to.point 'asis so t"at t"e entires$stem is in t"e form of a ring*

In t"is topolog$ data is transmittedin one direction onl$*

/"us t"e data packets circulate alongt"e ring in eit"er clockwise or

anticlockwise direction*


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Star

In star topolog$ a num'er ofworkstations 8or nodes: are directl$linked to a central ser)er*

&n$ communication 'etweenstations in a star 2&N must passt"roug" t"e central ser)er*

/"ere is 'i.directional communication'etween )arious nodes*

/"e central ser)er controls all t"eacti)ities of t"e nodes*


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$'rid

& comple com'ination of t"e 'asictopologies is known as a "$'ridtopolog$*

& "$'rid is a com'ination of two ormore 'asic network topologies( suc"as a star.'us( star.ring( or tieredtopolog$*

In a "$'rid topolog$( central and

distri'uted topologies are com'inedto meet t"e needs of an organi4ation*


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$'rid

Star Wired !s

In a star.wired'us topolog$(

groups ofworkstations arestar.connectedto connecti)it$de)ices and t"en

networked )ia asingle 'us(

Star Wired "in#

/"e star.wiredring topolog$

uses t"ep"$sical la$outof a star inconunction wit"t"e ring logical

topolog$*


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$'rid

Star !ired Bus

Star !ired 5ing


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Network /opologies

Bus &ll de)ices are connected to a central ca'le( called t"e

'us or 'ack'one* Bus networks are relati)el$ inepensi)eand eas$ to install for small networks*

Star &ll de)ices are connected to a central de)ice( called a

"u'* Star networks are relati)el$ eas$ to install and

manage( 'ut 'ottlenecks can occur 'ecause all data must

pass t"roug" t"e "u'*5ing &ll de)ices are connected to one anot"er in t"e s"ape of

a closed loop( so t"at eac" de)ice is connected directl$ to

two ot"er de)ices( one on eit"er side of it* 5ing

topologies are relati)el$ epensi)e and di>cult to install(

'ut t"e$ o-er "ig" 'andwidt" and can span large

distances*$'rid +roups of star.con%gured workstations are connected to

a linear 'us 'ack'one ca'le( com'ining t"e

c"aracteristics of t"e 'us and star topologies*


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/"e

NetworkingStandards

/"e

NetworkingStandards

* IS;C ?* I/,

* IS;

G* IC&NN

1* &NSI D* EI&6/I& 3* IEEE


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&NSI

&merican National Standards Institute 8&NSI: Composed of more t"an a t"ousand representati)es

from industr$ and go)ernment

5epresents ,nited States in setting international

standards &NSI standards documents a)aila'le7

&NSIHs !e' site 8www*ansi*org:

&t uni)ersit$ or pu'lic li'raries


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EI& and /I&

Electronic Industries &lliance 8EI&:7 /radeorgani4ation composed of representati)es fromelectronics manufacturing %rms across ,S Sets standards for its mem'ers

elps write &NSI standards 2o''ies for legislation fa)ora'le to growt" of computer

and electronics industries

/elecommunications Industr$ &ssociation 8/I&:7Focuses on standards for information tec"nolog$

8I/:( wireless( satellite( %'er optics( andtelep"one e=uipment


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IEEE

Institute of Electrical and Electronics Engineers

International societ$ composed of engineeringprofessionals

+oals are to promote de)elopment andeducation in electrical engineering and computerscience

IEEE tec"nical papers and standards are "ig"l$respected in t"e networking profession Can purc"ase IEEE documents online from IEEEHs !e'

site 8www*ieee*org:


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I/,

International /elecommunication ,nion

5egulates international telecommunications7 5adio and / fre=uencies

Satellite and telep"on$ speci%cations

Networking infrastructure

/ari-s applied to glo'al communications

/$picall$( documents pertain more to glo'altelecommunications issues t"an to industr$

tec"nical speci%cations


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IS;C

Internet Societ$ Professional mem'ers"ip societ$ t"at "elps to

esta'lis" tec"nical standards for t"e Internet ;)ersees groups wit" speci%c missions7

Internet &rc"itecture Board 8I&B:7 /ec"nical ad)isor$group of researc"ers and professionals

Interested in o)erseeing InternetHs designand management

Internet Engineering /ask Force 8IE/F:7 Sets standards

for "ow s$stems communicate o)er t"e Internet ow protocols operate and interact


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I&N& and IC&NN

Internet Protocol 8IP: addresses7 &ddresses usedto identif$ computers on t"e Internet and ot"er

/CP6IP.'ased networks

Internet &ssigned Num'ers &ut"orit$ 8I&N&:7

,sed to keep records of a)aila'le and reser)edIP addresses and determines "ow addresseswere doled out In 1G( coordinated e-orts wit" t"ree 5egional

Internet 5egistries 85I5s: Not.for.pro%t agenc$ t"at manages

distri'ution of IP addresses to pri)ate andpu'lic entities


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Principles ofcommunicationin networking

Principles ofcommunicationin networking

* Communication

pro'lem

1* BasicElements

D* /"erules

3* /erminologies


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asic Elements o$ aComm!nication System

Source Channel Destination


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asic Elements o$ aComm!nication System Source

/"is de)ice generates t"e data to 'etransmitted@ eamples are telep"onesand personal computers*

C"annel & medium t"at carries t"e message*

estination /"e recei)er 8sink: w"o recei)es t"e

message


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5ules of communications 'etweentwo points

/"ere are a num'er of p"ases t"at 'ot"de)ices must pass t"roug" in order toperform t"e common communicationsfunction of %le transfer

/"ese p"ases ensure t"at t"e softwareon eac" de)ice is structured to correctfor errors or inconsistencies from t"ecorresponding( remote de)ice*

ComputerBased e)ice

1

ComputerBased e)ice

D

Transmission

Medium


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Esta'lis" a link

e)ice 1 c"ecks to see if e)ice D ispresent on t"e link '$ sending a speci%cJen=uir$J message*

If t"e link is acti)e and de)ice D is acti)e

t"en it s"ould respond '$ sending 'ack anJacknowledgementJ message*

e)ice 1 must track t"e time t"at de)ice Dtakes to respond*

If de)ice D does not respond wit"in a timeinter)al 8de%ned '$ t"e protocol: t"ende)ice 1 assumes t"at t"e link is not acti)e*

/"is is called a transmission Jtime.outJ

error


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Issue a command and command=uali%er e)ice 1 sends de)ice D a message(

in a prede%ned format( w"ic" tellsde)ice D t"at a %le is to 'etransferred*

&s a =uali%er wit"in t"e message(de)ice 1 tells de)ice D w"at to dowit" t"e %le* For eample( de)ice 1ma$ tell de)ice D to place t"e

incoming %le onto disk storage( wit"t"e %le.name JF5EJ*


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&cknowledgment of command

If de)ice D "as correctl$ recei)ed t"ecommand and =uali%er from de)ice 1(and is capa'le of carr$ing out t"ecommand( t"en it sends de)ice 1 an

acknowledgement message* /"e acknowledgement message tells

de)ice 1 t"at it can now proceed wit"furt"er action needed to ful%l t"e

command* If de)ice D is una'le to act upon t"e

command from de)ice 1( t"en it mustrespond wit" an error message*


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&cknowledgment of command

&n error could occur on t"e recei)er if(for eample( t"e disk on w"ic" t"eincoming %le is to 'e stored( is alread$full*

/"e error response message would tellde)ice 1 t"at it s"ould not proceedwit" its proposed course of action*


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issection messages

&ll messages( command andot"erwise( must 'e 'roken down intopackets of managea'le si4e fortransmission*

/"us if an error s"ould occur in apacket( t"en onl$ t"at packet needsto 'e re.transmitted 8and not t"eentire message:*

/"erefore( w"en de)ice 1 wis"es totransfer a large %le to de)ice D( t"e%le is 'roken up into packets andtransmitted packet '$ packet*


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Error detection and correction

!"en de)ice 1 sends a messagepacket to de)ice D( it performs amat"ematical calculation8manipulation: on e)er$ unit of data

transmitted* /"is calculation is transmitted to

de)ice D immediatel$ after t"emessage*

e)ice D performs eactl$ t"e samemat"ematical calculation on itsincoming data as de)ice 1*


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Error detection and correction

e)ice D also reads in t"e calculation sent '$de)ice 1 and compares it wit" t"e localcalculation* If t"e two calculations pro)ide anidentical result( t"en it is assumed t"at t"e

incoming message was not corrupted on t"elink*

e)ice D can t"en issue a positi)eacknowledgement to de)ice 1 to indicatet"at it is read$ for t"e net message* If t"e

two calculations are inconsistent( t"en it isassumed t"at incoming data "as 'eencorrupted( and de)ice D issues a Jnegati)eacknowledgementJ message to de)ice 1(w"ic" indicates t"at t"e pre)ious data

message must 'e re.transmitted*


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/ermination of transmission

e)ice 1 transmits a %le( piece.wise(ensuring t"at eac" packet is correctl$recei)ed '$ de)ice D( using t"e tec"ni=uedescri'ed in (Error Detection and

Correction). &fter t"e last piece of t"e %le is

transmitted to de)ice D and positi)el$acknowledged( t"en de)ice 1 must

terminate t"e transmission* e)ice 1sends an Jend of transmissionJ messageto de)ice D* /"is allows de)ice D to closet"e stored %le and return to ot"er duties*


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/erminologies in relation tocommunication in networking essage Encoding

/"e e-ect of t"e skills( attitudes( andknowledge of t"e sender on t"e processof encoding t"e message*

essage Formatting & matter of agreement 'etween two

parties as to t"e form of t"e data to 'eec"anged or transmitted* For eample('ot" sides must use t"e same 'inar$

code for c"aracters*


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/erminologies in relation tocommunication in networking essage Si4e

t"e p"$sical dimensions and proportionsof message*

essage /iming

Includes speed matc"ing and se=uencingof message

essage Patterns Patterns of messages occur in two distinct

forms7 messages 'etween o'ects( calleda Protocol( and messages understood '$a particular kind of o'ect( called anInterface*


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Comm!nication %roblem

Contract Pattern Pro'lem7 ow can 'e"a)iours 'e de%ned

independent of implementations#

Correlation Identi%er Pro'lem7 In an$ messaging s$stem( a consumer

mig"t send se)eral message re=uests to di-erentser)ice pro)iders*

essage Se=uence Pro'lem7 Because of t"e in"erent distri'uted nature

of messaging( communication generall$ occurs o)er

a network* essage Epiration

Pro'lem7 essages are stored on disk or persistentmedia* !it" t"e growing num'er of messages( diskspace is consumed*


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Networking ardware

/$pes of network interface card

Install and con%gure NIC "ardware and software*Functions of 2&N connecti)it$ "ardware*

Build simple peer.to.peer network using /I&6EI&.?A.a or /I&6EI&.?A.' wiring standard*
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/$pes ;f Network Interface Card

Cards on an epansion 'oard inside acomputer 8PCI NIC( PCI Epress NIC:* It is used to connect Fast Et"ernet Networks

toget"er and it is connected to a PCI Slot located

on $our computerKs ot"er'oard Cards installed to t"e computerHs 'us

eternall$ 8PCCI& adapter( ,SB port(Fire!ire( Compact Flas" NIC: PCCI& 8Personal Computer emor$ Card

International &ssociation:( ,SB 8uni)ersal serial'us:( CompactFlas"( or Fire!ire 8IEEE 13: slotscan all 'e used to connect perip"erals suc" asNICs* ;ne ad)antage to eternall$ attac"ed NICs ist"eir simple installation*


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;n.'oard NIC & NIC t"at is integrated into a computerHs

mot"er'oard( rat"er t"an connected )iaan epansion slot or perip"eral 'us*

Not all perip"eral de)ices are connectedto a computerHs mot"er'oard )ia anepansion slot or perip"eral 'us*

Some are connected directl$ to t"emot"er'oard using on.'oard ports*

For eample( t"e electrical connectiont"at controls a computerHs mouseoperates t"roug" an on.'oard port( asdoes t"e connection for its ke$'oard andmonitor*


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!ireless NIC NICs are designed for use wit" eit"er

wired or wireless networks* !ireless NICs(w"ic" contain antennas to send andrecei)e signals*

;ne disad)antage to using wireless NICsis t"at currentl$ t"e$ are somew"at moreepensi)e t"an wire.'ound NICs using t"esame 'us t$pe


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Functions of 2&N connecti)it$"ardware 5epeater

u' 6 Switc"

Bridges

5outers

+atewa$s


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5epeater

Since a signal loses strengt" as itpasses along a ca'le( it is often

necessar$ to 'oost t"e signal wit" ade)ice called a repeater*

/"e repeater electricall$ ampli%est"e signal it recei)es and

re'roadcasts it* 5epeaters can 'e separate de)ices or

t"e$ can 'e incorporated into aconcentrator*


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u' 6 Switc"

& concentrator is a de)ice t"atpro)ides a central connection point forca'les from workstations( ser)ers( andperip"erals*

In a star topolog$( twisted.pair wire isrun from eac" workstation to a centralswitc"6"u'*

ost switc"es are acti)e( t"at is t"e$

electricall$ amplif$ t"e signal as itmo)es from one de)ice to anot"er*


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u' 6 Switc"

Switc"es no longer 'roadcast networkpackets as "u's did in t"e past( t"e$memori4e addressing of computersand send t"e information to t"e

correct location directl$*


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Bridges

& 'ridge is a de)ice t"at allows $outo segment a large network into twosmaller( more e>cient networks*

If $ou are adding to an older wiringsc"eme and want t"e new network to'e up.to.date( a 'ridge can connectt"e two*

& 'ridge monitors t"e informationtra>c on 'ot" sides of t"e networkso t"at it can pass packets ofinformation to t"e correct location*


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Bridges

ost 'ridges can JlistenJ to t"enetwork and automaticall$ %gure outt"e address of eac" computer on

'ot" sides of t"e 'ridge* /"e 'ridge can inspect eac" message

and( if necessar$( 'roadcast it on t"eot"er side of t"e network*

/"e 'ridge manages t"e tra>c tomaintain optimum performance on'ot" sides of t"e network


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5outers

5outer is intelligent de)ice w"ic" routesdata to destination computers*

It "elps in connecting two di-erent logicaland p"$sical networks toget"er*

In small network ser)er is connected torouter along wit" clients forcommunication*

!it" routers network communication is not

possi'le@ it is soul of network wit"outw"ic" distri'ution if internet and ot"ernetwork data to entire network areimpossi'le*


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5outers


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+atewa$s

&s name suggests it some kind ofpassing t"roug" to somet"ing*Interestingl$ gatewa$s can 'e

software or it can also 'e de)ice* +atewa$ de)ice connects 2&N wit"

internet* Its 'asic functionalit$ is topro)ide securit$ to t"e network*

B$ using gatewa$s incoming6outgoing tra>c can 'e monitored foran$ malicious acti)it$ wit"in t"enetwork w"ic" can 'e "armful tonetwork integrit$*


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