net working project

7/27/2019 Net Working Project

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Net Working Project Topics

1. What is computer network

2. History

3. Properties

4. Communication Meia

a. Wire Techno!ogies

". Wire!ess Techno!ogies

#. Communications Protoco!s $ Network Programming

a. %thernet

". &nternet Protoco! 'uite

(. 'ca!e

a. Persona! )rea Network

". *oca! )rea Network

c. Home )rea Network

. Campus )rea Network

e. Metropo!itan )rea Network

+. Wie )rea Network

g. ,irtua! Pri-ate Network

. /rgani0ationa! 'cope

a. &ntranets $ %tranets

. Network Topo!ogies

. asic Harware Components

a. N&C


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". 5epeaters $ Hu"s

c. riges

. 'witches

e. 5outers

+. 6irewa!!s

17. Network Protoco!s

a. TCP8&P

". /'& Moe!

Introduction to TCP/IP

Summary: TCP and IP were developed by a Department of Defense (DOD) research project toconnect a number dfferent networ!s des"ned by dfferent vendors nto a networ! of networ!s(the #Internet#)$ It was ntally successful because t delvered a few basc servces that everyoneneeds (fle transfer% electronc mal% remote lo"on) across a very lar"e number of clent andserver systems$ Several computers n a small department can use TCP&IP (alon" wth otherprotocols) on a sn"le '$ The IP component provdes routn" from the department to theenterprse networ!% then to re"onal networ!s% and fnally to the "lobal Internet$ On the

battlefeld a communcatons networ! wll sustan dama"e% so the DOD des"ned TCP&IP to berobust and automatcally recover from any node or phone lne falure$ Ths des"n allows theconstructon of very lar"e networ!s wth less central mana"ement$ *owever% because of theautomatc recovery% networ! problems can "o unda"nosed and uncorrected for lon" perods oftme$

s wth all other communcatons protocol% TCP&IP s composed of layers:

IP9 is responsi"!e +or mo-ing packet o+ ata +rom noe to noe. &P +orwars each packet

"ase on a +our "yte estination aress :the &P num"er;. The &nternet authoritiesassign ranges o+ num"ers to i++erent organi0ations. The organi0ations assign groups o+

their num"ers to epartments. &P operates on gateway machines that mo-e ata +romepartment to organi0ation to region an then aroun the wor!. TCP9 is responsi"!e +or -eri+ying the correct e!i-ery o+ ata +rom c!ient to ser-er.


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Network of Lowest Bidders

The rmy puts out a bd on a computer and D+C wns the bd$ The r ,orce puts out a bd andI-. wns$ The avy bd s won by /nsys$ Then the Presdent decdes to nvade 0renada andthe armed forces dscover that ther computers cannot tal! to each other$ The DOD must buld a

#networ!# out of systems each of whch% by law% was delvered by the lowest bdder on a sn"lecontract$

The Internet Protocol was developed to create a etwor! of etwor!s (the #Internet#)$ Indvdualmachnes are frst connected to a ' (+thernet or To!en 1n")$ TCP&IP shares the ' wthother uses (a ovell fle server% 2ndows for 2or!"roups peer systems)$ One devce provdesthe TCP&IP connecton between the ' and the rest of the world$

To nsure that all types of systems from all vendors can communcate% TCP&IP s absolutelystandard3ed on the '$ *owever% lar"er networ!s based on lon" dstances and phone lnes aremore volatle$ In the /S% many lar"e corporatons would wsh to reuse lar"e nternal networ!s

based on I-.4s S$ In +urope% the natonal phone companes tradtonally standard3e on5$67$ *owever% the sudden e8ploson of h"h speed mcroprocessors% fber optcs% and d"talphone systems has created a burst of new optons: ISD% frame relay% ,DDI% synchronousTransfer .ode (T.)$ ew technolo"es arse and become obsolete wthn a few years$ 2thcable T9 and phone companes competn" to buld the atonal Informaton Superh"hway% nosn"le standard can "overn ctywde% natonwde% or worldwde communcatons$

The or"nal des"n of TCP&IP as a etwor! of etwor!s fts ncely wthn the currenttechnolo"cal uncertanty$ TCP&IP data can be sent across a '% or t can be carred wthn annternal corporate S networ!% or t can p""ybac! on the cable T9 servce$ ,urthermore%machnes connected to any of these networ!s can communcate to any other networ! throu"h

"ateways suppled by the networ! vendor$

Addresses

+ach technolo"y has ts own conventon for transmttn" messa"es between two machnes wthnthe same networ!$ On a '% messa"es are sent between machnes by supplyn" the s8 byteunue dentfer (the #.C# address)$ In an S networ!% every machne has 'o"cal /ntswth ther own networ! address$ D+C+T% ppletal!% and ovell IP5 all have a scheme forass"nn" numbers to each local networ! and to each wor!staton attached to the networ!$

On top of these local or vendor specfc networ! addresses% TCP&IP ass"ns a unue number toevery wor!staton n the world$ Ths #IP number# s a four byte value that% by conventon% se8pressed by convertn" each byte nto a decmal number (; to 677) and separatn" the byteswth a perod$ ,or e8ample% the PC 'ube and Tune server s


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last byte dentfes the ndvdual computer$ The author followed ths procedure and was ass"nedthe numbers 6$=7$>


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A Uncertain Path

+very tme a messa"e arrves at an IP router% t ma!es an ndvdual decson about where to sendt ne8t$ There s concept of a sesson wth a preselected path for all traffc$ Consder a companywth facltes n ew or!% 'os n"eles% Chca"o and tlanta$ It could buld a networ! from

four phone lnes formn" a loop ( to Chca"o to ' to tlanta to )$ messa"e arrvn" atthe router could "o to ' va ether Chca"o or tlanta$ The reply could come bac! the otherway$

*ow does the router ma!e a decson between routesG There s no correct answer$ Traffc couldbe routed by the #cloc!wse# al"orthm ("o to tlanta% ' to Chca"o)$ The routers couldalternate% sendn" one messa"e to tlanta and the ne8t to Chca"o$ .ore sophstcated routn"measures traffc patterns and sends data throu"h the least busy ln!$

If one phone lne n ths networ! brea!s down% traffc can stll reach ts destnaton throu"h aroundabout path$ fter losn" the to Chca"o lne% data can be sent to tlanta to ' to

Chca"o$ Ths provdes contnued servce thou"h wth de"raded performance$ Ths !nd ofrecovery s the prmary des"n feature of IP$ The loss of the lne s mmedately detected by therouters n and Chca"o% but somehow ths nformaton must be sent to the other nodes$Otherwse% ' could contnue to send messa"es throu"h Chca"o% where they arrve at a#dead end$# +ach networ! adopts some 1outer Protocol whch perodcally updates the routn"tables throu"hout the networ! wth nformaton about chan"es n route status$

If the s3e of the networ! "rows% then the comple8ty of the routn" updates wll ncrease as wllthe cost of transmttn" them$ -uldn" a sn"le networ! that covers the entre /S would beunreasonably complcated$ ,ortunately% the Internet s des"ned as a etwor! of etwor!s$ Thsmeans that loops and redundancy are bult nto each re"onal carrer$ The re"onal networ!

handles ts own problems and reroutes messa"es nternally$ Its 1outer Protocol updates the tablesn ts own routers% but no routn" updates need to propa"ate from a re"onal carrer to the S,spne or to the other re"ons (unless% of course% a subscrber swtches permanently from onere"on to another)$

Undiagnosed Problems

I-. des"ns ts S networ!s to be centrally mana"ed$ If any error occurs% t s reported to thenetwor! authortes$ -y des"n% any error s a problem that should be corrected or repared$ IPnetwor!s% however% were des"ned to be robust$ In battlefeld condtons% the loss of a node or

lne s a normal crcumstance$ Casualtes can be sorted out later on% but the networ! must stay up$So IP networ!s are robust$ They automatcally (and slently) reconf"ure themselves whensomethn" "oes wron"$ If there s enou"h redundancy bult nto the system% then communcatons mantaned$

In H7 when S was des"ned% such redundancy would be prohbtvely e8pensve% or t m"hthave been ar"ued that only the Defense Department could afford t$ Today% however% smple


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routers cost no more than a PC$ *owever% the TCP&IP des"n that% #+rrors are normal and can belar"ely "nored%# produces problems of ts own$

Data traffc s freuently or"an3ed around #hubs%# much l!e arlne traffc$ One could ma"nean IP router n tlanta routn" messa"es for smaller ctes throu"hout the Southeast$ The problem

s that data arrves wthout a reservaton$ rlne companes e8perence the problem aroundmajor events% l!e the Super -owl$ Eust before the "ame% everyone wants to fly nto the cty$fter the "ame% everyone wants to fly out$ Imbalance occurs on the networ! when somethn"new "ets advertsed$ dam Curry announced the server at #mtv$com# and hs re"onal carrerwas swamped wth traffc the ne8t day$ The problem s that messa"es come n from the entreworld over h"h speed lnes% but they "o out to mtv$com over what was then a slow speed phonelne$

Occasonally a snow storm cancels fl"hts and arports fll up wth stranded passen"ers$ .any "ooff to hotels n town$ 2hen data arrves at a con"ested router% there s no place to send theoverflow$ +8cess pac!ets are smply dscarded$ It becomes the responsblty of the sender to

retry the data a few seconds later and to persst untl t fnally "ets throu"h$ Ths recovery sprovded by the TCP component of the Internet protocol$

TCP was des"ned to recover from node or lne falures where the networ! propa"ates routn"table chan"es to all router nodes$ Snce the update ta!es some tme% TCP s slow to ntaterecovery$ The TCP al"orthms are not tuned to optmally handle pac!et loss due to traffccon"eston$ Instead% the tradtonal Internet response to traffc problems has been to ncrease thespeed of lnes and eupment n order to say ahead of "rowth n demand$

TCP treats the data as a stream of bytes$ It lo"cally ass"ns a seuence number to each byte$ TheTCP pac!et has a header that says% n effect% #Ths pac!et starts wth byte =H>B?6 and contans

6;; bytes of data$# The recever can detect mssn" or ncorrectly seuenced pac!ets$ TCPac!nowled"es data that has been receved and retransmts data that has been lost$ The TCPdes"n means that error recovery s done endtoend between the Clent and Server machne$There s no formal standard for trac!n" problems n the mddle of the networ!% thou"h eachnetwor! has adopted some ad hoc tools$

Need to Know

There are three levels of TCP&IP !nowled"e$ Those who admnster a re"onal or natonalnetwor! must des"n a system of lon" dstance phone lnes% dedcated routn" devces% and verylar"e conf"uraton fles$ They must !now the IP numbers and physcal locatons of thousands of

subscrber networ!s$ They must also have a formal networ! montor strate"y to detect problemsand respond uc!ly$

+ach lar"e company or unversty that subscrbes to the Internet must have an ntermedate levelof networ! or"an3aton and e8pertse$ half do3en routers m"ht be conf"ured to connectseveral do3en departmental 's n several buldn"s$ ll traffc outsde the or"an3aton wouldtypcally be routed to a sn"le connecton to a re"onal networ! provder$


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*owever% the end user can nstall TCP&IP on a personal computer wthout any !nowled"e ofether the corporate or re"onal networ!$ Three peces of nformaton are reured:


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Network !ayer &P &P-( )5P


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There s some dscusson about how to map the TCP&IP model onto the OSI model$ Snce theTCP&IP and OSI protocol sutes do not match precsely% there s no one correct answer$

In addton% the OSI model s not really rch enou"h at the lower layers to capture the truelayern" there needs to be an e8tra layer (the Internetwor!n" layer) between the Transport and

etwor! layers$ Protocols specfc to a partcular networ! type% but whch are run on top of thebasc hardware framn"% ou"ht to be at the etwor! layer$ +8amples of such protocols are 1P%and the Spannn" Tree Protocol (used to !eep redundant brd"es dle untl they are needed)$*owever% they are local protocols% and operate beneath the nternetwor! functonalty to placeboth "roups (not to menton also protocols whch run on top of the nternetwor! protocol% such asIC.P) all at the same layer can be confusn"$

The follown" da"ram attempts to show where varous TCP&IP and other protocols would resden the or"nal OSI model:

Application e.g. HTTP> 'MTP> 'NMP> 6TP>Te!net> scp> N6'> 5T'P

(Presentatio

ne.g. ?M*> ? )'N.1> 'M> )6P

# Sessione.g. T*'>''H>&'/ 32 8 CC&TT ?.22#> 5PC>Net&/'>

)'P

4 Transport e.g. TCP> =

5TP> 'CTP> 'P?> )TP

3 Networke.g. &P> &CMP> &@MP> ?.2#> C*NP> )5P> 5)5P> /'P6>

5&P> &P?> PPP> H 6rame re!ay>

&' )TM

1 Physical e.g. e!ectricity> raio> !aser

Commonly% the top three layers of the OSI model (pplcaton% Presentaton and Sesson) areconsdered as a sn"le pplcaton 'ayer n the TCP&IP sute$ -ecause the TCP&IP sute has nounfed sesson layer on whch h"her layers are bult% these functons are typcally carred out (or"nored) by ndvdual applcatons$ smplfed TCP&IP nterpretaton of the stac! s shownbelow:

Applicatio

n

"layer 7"

e.g. HTTP>6TP>


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4 Transport

e.g. TCP> =

5TP> 'CTP

(routing protocols like #P$, which run over IP, may also be consiere part of

the %etwork layer!

3 Network

6or TCP8&P this is the &nternet Protoco!:&P;

(re&uire protocols like I'P an I)P run over IP, but may still be consiere

part of the network layer* +RP oes not run over IP!

2 Data Link e.g. %thernet> Token ring> etc.

1 Physical e.g. physica! meia> an encoing techniAues> T1> %1

The Physical layer

The Physcal layer descrbes the physcal characterstcs of the communcaton% such asconventons about the nature of the medum used for communcaton (such as wres% fber optcln!s or rado ln!s)% and all related detals such as connectors% channel codes and modulaton%s"nal stren"ths% wavelen"th% lowlevel sychron3aton and tmn" and ma8mum dstances$

The Data-Link layer

The Data ln! layer specfes how pac!ets are transported over the physcal layer% ncludn" theframing($e$ the specal bt patterns whch mar! the start and end of pac!ets)$ +thernet% fore8ample% ncludes felds n the pac!et header whch specfy whch machne or machnes on thenetwor! a pac!et s destned for$ +8amples of Dataln! layer protocols are +thernet% 2reless

+thernet% S'IP% To!en 1n" and T.$

PPP s a lttle more comple8% as t was or"nally specfed as a separate protocol whch ran ontop of another data ln! layer% *D'C&SD'C$

Ths layer s sometmes further subdvded nto 'o"cal 'n! Control and .eda ccess Control$

The Network layer

s or"nally defned% the etwor! layer solved the problem of "ettn" pac!ets across a sn"lenetwor!$ +8amples of such protocols are 5$67% and the 1P+T4s Intal Connecton Protocol$

2th the advent of the concept ofnternetwor!n"%addtonal functonalty was added to thslayer% namely "ettn" data from the source networ!to the destnaton networ!$ Ths "enerallynvolves routn" the pac!et across a networ! of networ!s% !nown as an nternet$ In the nternetprotocol sute% IPperforms the basc tas! of "ettn" pac!ets of data from source to destnaton%and also supports other protocols% such as IC.P (used to transmt da"nostc nformaton aboutIP transmsson) and I0.P (used to mana"e multcast data)$ IC.P and I0.P are layered on top
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of IP but perform networ! layer functons% llustratn" an ncompatblty between the nternetand OSI models$

The etwor! 'ayerInternet Protocol(IP) can carry data for a number of dfferent h"her levelprotocols$ These protocols are each dentfed by a unueIP Protocol Number$ IC.P and I0.P

are protocols < and 6% respectvely$

The Transport layer

The protocols at the Transport layer can solve problems l!e relablty (#dd the data reach thedestnatonG#) and ensure that data arrves n the correct order$ In the TCP&IP protocol sute%transport protocols also determne whch applcaton any "ven data s ntended for$

The dynamc routn" protocols whch techncally ft at ths layer n the TCP&IP Protocol Sute(snce they run over IP) are "enerally consdered to be part of the etwor! layer an e8ample sOSP, (IP protocol number J>)$

TCP (IP protocol number B) s a #relable#% connectonorented transport mechansm provdn" arelable byte stream% whch ma!es sure data arrves undama"ed and n order% s retransmtted flost% and elmnates duplcate copes$ TCP tres to contnuously measure how loaded the networ!s and throttles ts sendn" rate n order to avod overloadn" the networ!$ ,urthermore% TCP wllattempt to delver all data correctly n the specfed seuence$ These are ts man dfferences from/DP and can become dsadvanta"es n realtme streamn" or routn" applcatons wth h"hlayer = loss rates$

/DP (IP protocol number


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These pro"rams and ther correspondn" protocols nclude *TTP(The 2orld 2de 2eb)% ,TP(,le transport)% S.TP (+mal)% SS*(Secure remote lo"n)% DS(ame KL IP ddressloo!ups) and many others$

pplcatons most commonly run on TCP or /DP% and are often assocated wth a well!nown

port number$ Some e8amples are:

HTTP on TCP port 7 or 77.

''H on TCP port 22>


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Physica! meium attachment> accommoating -arious possi"i!ities in the meium

o Wi!! an eterna! transcei-er :M)=; "e use to connect to the meiumE

o How many pins o the connectors ha-e an what is each pin use +orE

Transmission techniAue etermines whether the encoe "its wi!! "e transmitte "y"ase"an :igita!; or "roa"an :ana!og; signa!ing.

Physica! meium transmission transmits "its as e!ectrica! or optica! signa!s appropriate

+or the physica! meium> an etermines

o What physica! meium options can "e use

o How many -o!ts8" shou! "e use to represent a gi-en signa! state> using a

gi-en physica! meium

DATA LIN" LAY!

The ata !ink !ayer pro-ies error9+ree trans+er o+ ata +rames +rom one noe to another o-er thephysica! !ayer> a!!owing !ayers a"o-e it to assume -irtua!!y error9+ree transmission o-er the !ink.

To o this> the ata !ink !ayer pro-ies

*ink esta"!ishment an termination esta"!ishes an terminates the !ogica! !ink "etween

two noes.

6rame tra++ic contro! te!!s the transmitting noe to D"ack9o++D when no +rame "u++ers are

a-ai!a"!e.

6rame seAuencing transmits8recei-es +rames seAuentia!!y.

6rame acknow!egment pro-ies8epects +rame acknow!egments. eciing which physica! path the ata

shou! take "ase on network conitions> priority o+ ser-ice> an other +actors. &t pro-ies

5outing routes +rames among networks.

'u"net tra++ic contro! routers :network !ayer intermeiate systems; can instruct a

sening station to Dthrott!e "ackD its +rame transmission when the routerBs "u++er +i!!s up.


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6rame +ragmentation i+ it etermines that a ownstream routerBs maimum transmission

unit :MT=; si0e is !ess than the +rame si0e> a router can +ragment a +rame +ortransmission an re9assem"!y at the estination station.

*ogica!9physica! aress mapping trans!ates !ogica! aresses> or names> into physica!

aresses.

'u"net usage accounting has accounting +unctions to keep track o+ +rames +orware

"y su"net intermeiate systems> to prouce "i!!ing in+ormation.

Communications Subnet

The network !ayer so+tware must "ui! heaers so that the network !ayer so+tware resiing in the

su"net intermeiate systems can recogni0e them an use them to route ata to the estination

aress.

This !ayer re!ie-es the upper !ayers o+ the nee to know anything a"out the ata transmission

an intermeiate switching techno!ogies use to connect systems. &t esta"!ishes> maintains an

terminates connections across the inter-ening communications +aci!ity :one or se-era!

intermeiate systems in the communication su"net;.

&n the network !ayer an the !ayers "e!ow> peer protoco!s eist "etween a noe an its

immeiate neigh"or> "ut the neigh"or may "e a noe through which ata is route> not the

estination station. The source an estination stations may "e separate "y many intermeiate

systems.

T!ANSP$!T LAY!

The transport !ayer ensures that messages are e!i-ere error9+ree> in seAuence> an with no

!osses or up!ications. &t re!ie-es the higher !ayer protoco!s +rom any concern with the trans+er o+ata "etween them an their peers.

The si0e an comp!eity o+ a transport protoco! epens on the type o+ ser-ice it can get +rom

the network !ayer. 6or a re!ia"!e network !ayer with -irtua! circuit capa"i!ity> a minima! transport

!ayer is reAuire. &+ the network !ayer is unre!ia"!e an8or on!y supports atagrams> the transport

protoco! shou! inc!ue etensi-e error etection an reco-ery.

The transport !ayer pro-ies

Message segmentation accepts a message +rom the :session; !ayer a"o-e it> sp!its the

message into sma!!er units :i+ not a!reay sma!! enough;> an passes the sma!!er unitsown to the network !ayer. The transport !ayer at the estination station reassem"!es themessage.

Message acknow!egment pro-ies re!ia"!e en9to9en message e!i-ery with

acknow!egments.

Message tra++ic contro! te!!s the transmitting station to D"ack9o++D when no message

"u++ers are a-ai!a"!e.


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'ession mu!tip!eing mu!tip!ees se-era! message streams> or sessions onto one !ogica!

!ink an keeps track o+ which messages "e!ong to which sessions :see session !ayer;.

Typica!!y> the transport !ayer can accept re!ati-e!y !arge messages> "ut there are strict message

si0e !imits impose "y the network :or !ower; !ayer. ConseAuent!y> the transport !ayer must

"reak up the messages into sma!!er units> or +rames> prepening a heaer to each +rame.

The transport !ayer heaer in+ormation must then inc!ue contro! in+ormation> such as message

start an message en +!ags> to ena"!e the transport !ayer on the other en to recogni0e

message "ounaries. &n aition> i+ the !ower !ayers o not maintain seAuence> the transport

heaer must contain seAuence in+ormation to ena"!e the transport !ayer on the recei-ing en to

get the pieces "ack together in the right orer "e+ore haning the recei-e message up to the

!ayer a"o-e.

En-to-en layers

=n!ike the !ower Dsu"netD !ayers whose protoco! is "etween immeiate!y ajacent noes> the

transport !ayer an the !ayers a"o-e are true Dsource to estinationD or en9to9en !ayers> an

are not concerne with the etai!s o+ the uner!ying communications +aci!ity. Transport !ayer

so+tware :an so+tware a"o-e it; on the source station carries on a con-ersation with simi!ar

so+tware on the estination station "y using message heaers an contro! messages.

SSSI$N LAY!

The session !ayer a!!ows session esta"!ishment "etween processes running on i++erent

stations. &t pro-ies

'ession esta"!ishment> maintenance an termination a!!ows two app!ication processes

on i++erent machines to esta"!ish> use an terminate a connection> ca!!e a session. 'ession support per+orms the +unctions that a!!ow these processes to communicate o-er

the network> per+orming security> name recognition> !ogging> an so on.

P!SNTATI$N LAY!

The presentation !ayer +ormats the ata to "e presente to the app!ication !ayer. &t can "e

-iewe as the trans!ator +or the network. This !ayer may trans!ate ata +rom a +ormat use "y the

app!ication !ayer into a common +ormat at the sening station> then trans!ate the common +ormat

to a +ormat known to the app!ication !ayer at the recei-ing station.

The presentation !ayer pro-ies

Character coe trans!ation +or eamp!e> )'C&& to %C


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APPLICATI$N LAY!

The app!ication !ayer ser-es as the winow +or users an app!ication processes to access

network ser-ices. This !ayer contains a -ariety o+ common!y neee +unctions

5esource sharing an e-ice reirection

5emote +i!e access

5emote printer access

&nter9process communication

Network management


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5ea more


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Computer networking means connecting computers e!ectronica!!y to a!!ow sharing o+

resources. 5esources range +rom attache printers to +i!es> isk space an secure

in+ormation. There are three major categories o+ networks. Computers connect in the

same "ui!ing using *oca! )rea Networks :*)Ns;. Metropo!itan )rea Networks :M)Ns;

connect "ui!ings within a city. Wie )rea Networks :W)Ns; connect sites throughout a

country or aroun the wor!.

Computer networking means connecting computers e!ectronica!!y to a!!ow sharing o+

resources. 5esources range +rom attache printers to +i!es> isk space an secure

in+ormation. There are three major categories o+ networks. Computers connect in the

same "ui!ing using *oca! )rea Networks :*)Ns;. Metropo!itan )rea Networks :M)Ns;

connect "ui!ings within a city. Wie )rea Networks :W)Ns; connect sites throughout a

country or aroun the wor!.

Technolog$

.ost computer networ!s use +thernet or 2, as the ' technolo"y$ 2, s also!now as I+++ J;6$


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The second common applcaton for computer networ!n" was to share fles and ds!space$ ,les created on one computer can be used by someone wor!n" on anothercomputer accessn" the fle over the networ!$ Ths s the smplest form of electronccollaboraton$ Ths concept has been e8tended to create fle servers$ These are computerswth the man purpose of storn" and sharn" fles$ Computers can share fles locallyusn" the etwor! ,le System (,S) or Common Internet ,le System (CI,S)$ Securtybecomes crtcal when usn" networ!ed computers$ ou must decde who you want toaccess your fles and "ve them and only them the correct permssons$

*ide Area )ile Sharing

,S and CI,S are systems that wor! well n a local area wth h"h speed ln!s betweenthe computers$ They do not wor! well over lon" dstances where bandwdth between thecomputers may be lmted$ The ,le Transfer Protocol (,TP) was des"ned to transferfles over lon" dstances at slow or unpredctable speeds$ Transferrn" fles s not asnteractve as sharn" fles% but t stll allows for collaboraton$

*orld *ide *eb and Be$ond

In the late >;s% the *yper Te8t Transfer Protocol (*TTP) "aned wdespreadacceptance$ Ths allowed nformaton to be posted on a server n a standard mar!uplan"ua"e called the *yper Te8t .ar!up 'an"ua"e (*T.')$ *T.' also provdes a

mechansm for nput$ Ths s one of the man applcatons of computer networ!s snce theyear 6;;;$ 2eb pa"es can dsplay nformaton n a standard format and receve nputfrom the users to create surveys% shoppn" on lne and many other applcatons$

'eal Time A##lications


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s 6;


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-$#erte.t Transfer Protocol +-TTP,

*TTP s a type of networ! protocol that facltates hyperte8t sendn" and recevn"

between browsers and servers$ *TTP s a set of rules for transferrn" sound% "raphcs%te8t% vdeo and multmeda fles over the Internet$ user s ndrectly accessn" *TTP as

soon as he or she opens a 2eb browser$

1ead more: Defnton of etwor! Protocols M e*ow$comhttp:&&www$ehow$com&aboutNB?7H?6?Ndefntonnetwor!protocols$html833Jfv

)ile Transfer Protocol +)TP,

fle transfer protocol allows computers to e8chan"e fles over the Internet$ ,TP allows

users to copy% move% rename and delete fles from the Internet% n addton todownloadn" pro"rams or fles$

Point to Point Protocol +PPP,

PPP allows two nodes (computers% scanners% prnters or other networ! devces) to

establsh a connecton n a networ!$ It facltates compresson% encrypton andauthentcaton between the sender and recever$ ponttopont protocol s also used toconnect ndvdual computers over a dalup ISP (Internet servce provder) and lneconnectons$

"nternet /essage Access Protocol +"/AP,

I.P s a set of rules that allows a user to access emal from a local server$ It s a

clent&server protocol n whch emal s retreved from a secure Internet server$ userdecdes whether or not to download a partcular emal after readn" ts sender nformatonand headn"$ I.P allows users to create folders% delete and pur"e messa"es off theInternet server and manpulate malbo8es$ /sers have to be lo""ed nto ther Internetserver malbo8 whle usn" I.P$

1ead more: Defnton of etwor! Protocols M e*ow$comhttp:&&www$ehow$com&aboutNB?7H?6?Ndefntonnetwor!protocols$html833+T332

Hy(rid Topolo'y De%inition

The term #topolo"y# s used to descrbe the way n whch computers are connected to"ether on acomputer networ!$ Popular networ! topolo"es nclude bus% star and rn"% but t s possble fortwo or more basc topolo"es to be combned on a sn"le networ!% to form what s !nown as ahybrd topolo"y$
http://www.ehow.com/about_6457424_definition-network-protocols.html#ixzz1TD9Q8fAvhttp://www.ehow.com/about_6457424_definition-network-protocols.html#ixzz1TD9Q8fAvhttp://www.ehow.com/about_6457424_definition-network-protocols.html#ixzz1TD9ETzzWhttp://www.ehow.com/about_6457424_definition-network-protocols.html#ixzz1TD9ETzzWhttp://www.ehow.com/about_6457424_definition-network-protocols.html#ixzz1TD9Q8fAvhttp://www.ehow.com/about_6457424_definition-network-protocols.html#ixzz1TD9Q8fAvhttp://www.ehow.com/about_6457424_definition-network-protocols.html#ixzz1TD9ETzzWhttp://www.ehow.com/about_6457424_definition-network-protocols.html#ixzz1TD9ETzzW


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1ead more: *ybrd Topolo"y Defnton M e*ow$comhttp:&&www$ehow$com&factsNH7H>7J7Nhybrdtopolo"ydefnton$html8337J7Nhybrdtopolo"ydefnton$html833


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The &nternet as we know it toay is not the prouct o+ a !ong or sustaine e++ort "y any

sing!e research team. 5ather> it is the ama!gamation o+ the e++orts +rom some -ery "right

peop!e working inepenent!y o+ each other. Take a !ook at the time!ine shown in e++orts

Ta"!e 1.1. Most peop!e point to Kanuary 1> 13> as the ate when the &nternet was

"orn. The +o!!owing sections escri"e the most important o+ those e-ents in greater

etai!.

Ta"!e 1.1 &nternet Time!ine

777 Hosts

1 Worm )ttacks (>777 o+ &nternetBs (7>777 Hosts

1 &nternet %cees 177>777 Hosts

17 )5P)N%T


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)5P) :1#;

&n 1#> the =''5 !aunche 'putnik> the +irst man9mae earth sate!!ite. )s a resu!t> the=.'. +orme the )-ance 5esearch Projects )gency :)5P); uner the auspices the

Pau! aran at the 5an Corporation ponere a -ery simp!e pro"!em

How o you ensure that a mi!itary network wou! continue to operate e-en uner nuc!ear

attackE &n other wors> Pau!Bs jo" was to esta"!ish a way to get in+ormation across a

network so that there isnBt a sing!e point o+ +ai!ure.

The so!ution that Pau! aran came up with is now ca!!e Packet 'witching. ) network o+

computers sens messages :packets; that contain in+ormation a"out its route so that

any one computer on the network knows where to +orwar :switch; the message.

Nationa! Physica! *a"oratory create the +irst packet switching network in 1(.

)5P)N%T :1(;

)5P) create )5P)N%T in 1( to he!p )5P)9+une researchers co!!a"orate more

e++ecti-e!y. These researchers were eucation an research9oriente types> not the

commercia! organi0ations you see on the &nternet toay.

)5P) commissione o!t> eranek> an Newman to "ui! &nter+ace Message

Processors :&MPs;> which were "ase on the packet switching techno!ogy "ui!t at the

5an Corporation in the ear!y 1(7s. The +irst &MPs were positione at =C*)> 'tan+or

5esearch &nstitute> =ni-ersity o+ Ca!i+ornia at 'anta ar"ara> an =ni-ersity o+ =tah in

'a!t *ake City. &MPs ha-e e-o!-e into what we now ca!! &P routers.

TCP8&P :13;

The net major e-ent in the e-o!ution o+ the &nternet inBt occur unti! 13> when

)5P)N%T change o-er to the TCP8&P networking protoco!. etween 1( an 13> a


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-ariety o+ ini-iua! networks sproute an grew. &TN%T an C'N%T are among the

most nota"!e. Connecting each o+ these inepenent networks was i++icu!t> though>

"ecause they inBt use the same protoco!s an there+ore cou!nBt echange in+ormation.

)s a resu!t> )5P) commissione the e-e!opment o+ a new protoco! ca!!e

Transmission Contro! Protoco!8&nternet Protoco! :TCP8&P; that wou! a!!ow i++erent

networks to connect. These networks use &P to communicate with each other> an the

&MPs that switche packets "ecame known as gateways or routers. 'ince most

computer scientists ca!!e a network o+ networks an Dinternet>D this new arrangement o+

networks using TCP8&P "ecame known as the &nternet.

&ronica!!y> )5P)N%T was !ate making the change o-er to TCP8&P. Most other networks

ha change to TCP8&P in the !ate 17s> "ut )5P)N%T inBt make the change unti!

Kanuary 1> 13. Thus> many +o!ks consier that ate as the "irthay o+ the &nternet.

N'6 Creates N'6N%T :1(;

&n 1( the Nationa! 'cience 6ounation create N'6N%T> an &nternet "ack"one with a

spee o+ #(I. This "ack"one connecte +i-e super9computing centers !ocate at

Princeton> Pitts"urgh> =C' =&=C> an Corne!!. N'6N%T precipitate a !arge num"er

o+ connections +rom -arious uni-ersities.

The +o!!owing year> N'6 signe an agreement with Merit Network> &nc.> to cooperati-e!y

manage N'6N%T. Merit Network> &nc.> in-o!-e &M an MC& through their own

su"siiary agreements.

N'6N%T has "een upate continua!!y since 1(. &n 1> two years a+ter going

on!ine> the "ack"one was upgrae to T1 :1.#44M;. &n 11> it was upgrae to T3

:44.3(M;L N'6N%T gaine a!most a thousan times more "anwith than the origina!

N'6N%T "ack"one.

N/T% The eponentia! growth o+ the &nternet can "e pinpointe to the time that

N'6N%T went on!ine. Prior to N'6N%T> just o-er 1>777 hosts were on the &nternet. /-er

17>777 hosts "egan using on the &nternet the year N'6N%T went on!ine> an two years

!ater o-er (7>777 hosts were on the &nternet.

)5P)N%T &s


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/n Kune 1> 17> the origina! )5P)N%T was ismant!e. Newer networks connecte

the sites that )5P)N%T connecte> an thus )5P)N%T was no !onger use+u!. &tBs

interesting to note that no one su++ere an interruption in ser-ice when )5P)N%T was

remo-e. The techno!ogy ha pro-en so e++ecti-e that when )5P)N%T went own> the

&nternet +oun other paths +or the in+ormation to tra-e!.

The Wor! Wie We" :12;

Tim erners9*ee> a physicist at C%5N in 'wit0er!an> in-ente the Wor! Wie We"

:We"; in 12 as a way to organi0e in+ormation in a more "rain9!ike +ashion. His iea

was to a!!ow peop!e to make mu!tip!e +ree associations with i++erent "its o+ in+ormation.

His research was "ase on hypertet> a concept in-ente "y Te Ne!son as part o+ the

D?anau ProjectD in the 1(7s. Hypertet a!!ows an author to !ink a passage o+ tet to

another ocument so that when you acti-ate that !ink> the c!ient program opens the

ocument to which it re+ers. 5ecent a-ances ha-e e-o!-e hypertet into hypermeia>

which is simi!ar to hypertet "ut throws mu!timeia images> -ieos> an souns into the

mi.

)!though erners9*ee in-ente the We" +or his high9energy physics cronies> it took o++

an was Auick!y aopte "y many other groups on the &nternet. The We" has now

outpace e-ery other ser-ice such as @opher or W)&'. &t is so popu!ar now that the

We" is what most peop!e think o+ when one mentions the &nternet. &n +act> the growth

rate o+ the We" in 13 was estimate at o-er 347>777 percent.

N'6 %sta"!ishes &nterN&C :13;

N'6 create &nterN&C> a group o+ "usinesses that pro-ie a -ariety o+ essentia! ser-ices

to the &nternet. )T$T pro-ies irectory an ata"ase ser-ices. Network 'o!utions> &nc.>

pro-ies name registration ser-ices> &nterN&CBs primary ro!e> which you can !earn more

a"out in )ppeni > D5egistering an &mp!ementing our /wn 777 host

computers on the &nternet. Now there are mi!!ions o+ host computers an many more


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mi!!ions o+ actua! users. )!! o+ these users arenBt necessari!y connecte irect!y to the

&nternet. Howe-er> they can sti!! echange e9mai! with other &nternet users -ia &nternet

mai! gateways.

Whereas the origina! &nternet was intene +or research purposes> the &nternet is now

use preominant!y +or commercia! purposes. )s a resu!t> N'6 remo-e +rom its

accepta"!e usage po!icies a c!ause the prohi"ite commercia! use o+ the &nternet. ou

+in organi0ations se!!ing proucts on the &nternet or pro-iing a -ariety o+ ser-ices such

as news> mapping> searching> an more.

ou can attri"ute most o+ the commercia!ism to e-e!opments in the We". &n 12> the We"

was on!y suite to peop!e pu"!ishing research in+ormation. &n 1> howe-er> the We" is +u!!y

suite to create ynamic> interacti-e sites that are as enticing as many mu!timeia programs

you purchase on C$Thn"s to see of "rowth n the last =7 year of the computer networ!$In H? +thernet was to be verfed at the 5ero8 P1C lto computer networ!$ nd after nHJ the modem dal up connecton was ben" ntroducedafter HJ n J< Q the new TCP &% /I5 operatn" system was ben" released of the IP sute$The frst portable computer and t was promoted n s3e of almost a pound sutcaseIn J


28/62

Co&puter Networkin' and the Internet

Sectons $ Ulenroc! recalls thevery frst use of the networ! to perform a remote lo"n from /C' to S1I crashn" the systemUlenroc! >J$
http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Leiner%2098]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Kleinrock%201961]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Kleinrock%201964]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Baran%201964]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[DEC%201990]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Roberts%201967]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Roberts%201967]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Roberts%201967]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Kleinrock%201998]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Leiner%2098]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Kleinrock%201961]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Kleinrock%201964]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Baran%201964]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[DEC%201990]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Roberts%201967]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Roberts%201967]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Kleinrock%201998]


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!i"ure #$%-#&The +irst &nternet Message Processor :&MP;> with *. I!einrock

-y H6% 1Pnet had "rown to appro8mately J:
http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[RFC%20001]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Abramson%201972]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Abramson%201972]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Abramson%201972]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Cerf%201974]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Leiner%2098]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[RFC%20001]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Abramson%201972]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Cerf%201974]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Leiner%2098]


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minimalism' autonomy&a network shou! "e a"!e to operate on its own> with no

interna! changes reAuire +or it to "e internetworke with other networksL best effort ser(ice&internetworke networks wou! pro-ie "est e++ort> en9to9en

ser-ice. &+ re!ia"!e communication was reAuire> this cou! accomp!ishe "yretransmitting !ost messages +rom the sening hostL

stateless routers&the routers in the internetworke networks wou! not maintain anyper9+!ow state a"out any ongoing connection

ecentrali)e control&there wou! "e no g!o"a! contro! o-er the internetworke

networks.

These princip!es continue to ser-e as the architectura! +ounation +or toayBs &nternet> e-en 2#

years !ater 9 a testament to insight o+ the ear!y &nternet esigners.

These archtectural prncples were emboded n the TCP protocol$ The early versons of TCP%however% were ute dfferent from today4s TCP$ The early versons of TCP combned a relable

nseuence delvery of data va end system retransmsson (stll part of today4s TCP) wthforwardn" functons (whch today are performed by IP)$ +arly e8permentaton wth TCP%combned wth the reco"nton of the mportance of an unrelable% nonflowcontrolled endendtransport servce for applcaton such as pac!et3ed voce% led to the separaton of IP out of TCPand the development of the /DP protocol$ The three !ey Internet protocols that we see today TCP% /DP and IP were conceptually n place by the end of the H;4s$

In addton to the D1P Internetrelated research% many other mportant networ!n" actvteswere underway$ In *awa% orman bramson was developn" 'O*net% a pac!etbasedrado networ! that allowed multple remote stes on the *awaan slands to communcate wtheach other$ The 'O* protocol bramson H; was the frst socalled multple access

protocol% allown" "eo"raphcally dstrbuted users to share a sn"le broadcast communcatonmedum (a rado freuency)$ bramson4s wor! on multple access protocols was bult upon by1obert .etcalfe n the development of the +thernet protocol .etcalfe HB for wrebasedshared broadcast networ!s$ Interestn"ly% .etcalfe4s +thernet protocol was motvated by theneed to connect multple PCs% prnters% and shared ds!s to"ether Per!ns >?$ Twentyfveyears a"o% well before the PC revoluton and the e8ploson of networ!s% .etcalfe and hscollea"ues were layn" the foundaton for today4s PC 's$ +thernet technolo"y represented anmportant step for nternetwor!n" as well$ +ach +thernet local area networ! was tself anetwor!% and as the number of 's prolferated% the need to nternetwor! these 's to"etherbecame all the more mportant$ n e8cellent source for nformaton on +thernet s Spur"eon4s+thernet 2eb Ste% whch ncludes .etcalfe4s drawn" of hs +thernet concept% as shown belown ,"ure 6$ 2e dscuss +thernet% loha% and other ' technolo"es n detal n Chapter 7
http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Abramson%201972]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Metcalfe%201976]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Perkins%201994]http://if%28confirm%28%27http//wwwhost.ots.utexas.edu/ethernet/%20%20%5Cn%5CnThis%20file%20was%20not%20retrieved%20by%20Teleport%20Pro,%20because%20it%20is%20addressed%20on%20a%20domain%20or%20path%20outside%20the%20boundaries%20set%20for%20its%20Starting%20Address.%20%20%5Cn%5CnDo%20you%20want%20to%20open%20it%20from%20the%20server?%27))window.location=%27http://wwwhost.ots.utexas.edu/ethernet/%27http://if%28confirm%28%27http//wwwhost.ots.utexas.edu/ethernet/%20%20%5Cn%5CnThis%20file%20was%20not%20retrieved%20by%20Teleport%20Pro,%20because%20it%20is%20addressed%20on%20a%20domain%20or%20path%20outside%20the%20boundaries%20set%20for%20its%20Starting%20Address.%20%20%5Cn%5CnDo%20you%20want%20to%20open%20it%20from%20the%20server?%27))window.location=%27http://wwwhost.ots.utexas.edu/ethernet/%27http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Abramson%201972]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Metcalfe%201976]http://210.43.128.116/jsjwl/net/kurose/introduction/history.htm#[Perkins%201994]http://if%28confirm%28%27http//wwwhost.ots.utexas.edu/ethernet/%20%20%5Cn%5CnThis%20file%20was%20not%20retrieved%20by%20Teleport%20Pro,%20because%20it%20is%20addressed%20on%20a%20domain%20or%20path%20outside%20the%20boundaries%20set%20for%20its%20Starting%20Address.%20%20%5Cn%5CnDo%20you%20want%20to%20open%20it%20from%20the%20server?%27))window.location=%27http://wwwhost.ots.utexas.edu/ethernet/%27http://if%28confirm%28%27http//wwwhost.ots.utexas.edu/ethernet/%20%20%5Cn%5CnThis%20file%20was%20not%20retrieved%20by%20Teleport%20Pro,%20because%20it%20is%20addressed%20on%20a%20domain%20or%20path%20outside%20the%20boundaries%20set%20for%20its%20Starting%20Address.%20%20%5Cn%5CnDo%20you%20want%20to%20open%20it%20from%20the%20server?%27))window.location=%27http://wwwhost.ots.utexas.edu/ethernet/%27


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)igure %&104: HB drawn" by 1$ .etcalfe of the +thernet concept (from Charles Spur"eon4s+thernet 2eb Ste)

In addton to the D1P nternetwor!n" efforts and the loha&+thernet multple access

networ!s% a number of companes were developn" ther own propretary networ! archtectures$D"tal +upment Corporaton (D"tal) released the frst verson of the D+Cnet n H7%allown" two PDP;4s$

It s also worth notn" here that n the J;4s (and even before)% researchers (see% e$"$% ,raserJ=% Turner JB%,raser >=) were also developn" a #compettor# technolo"y to the Internetarchtecture$ These efforts have contrbuted to the development of the T. (synchronous

Transfer .ode) archtecture% a connectonorented approach based on the use of f8ed s3epac!ets% !nown as cells$ 2e wll e8amne portons of the T. archtecture throu"hout thsboo!$

)*. - )**. A Proli%eration o% Networks

y the en o+ the 17Bs approimate!y 277 hosts were connecte to the )5P)net. y the en

o+ the 17Bs the num"er o+ host connecte to the pu"!ic &nternet> a con+eeration o+ networks

!ooking much !ike toayBs &nternet wou! reach 177>777. The 17Bs wou! "e a time o+

tremenous growth.

.uch of the "rowth n the early J;4s resulted from several dstnct efforts to create computernetwor!s ln!n" unverstes to"ether$ -ITnet (-ecause It4s There +Twor!) provded emaland fle transfers amon" several unverstes n the ortheast$ CS+T (Computer Scence+Twor!) was formed to ln! to"ether unversty researchers wthout access to 1Pnet$ InJB% S,+T was created to provde access to S,sponsored supercomputn" centers$Startn" wth an ntal bac!bone speed of 7BUbps% S,+T4s bac!bone would be runnn" at


32/62

In the 1Pnet communty% many of the fnal peces of today4s Internet archtecture werefalln" nto place$ Eanuary


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222$ The or"nal C+1 browsers only provded a lnemode nterface$ round the end of>6 there were about 6;; 2eb servers n operaton% ths collecton of servers ben" the tp ofthe ceber" for what was about to come$ t about ths tme several researchers were developn"2eb browsers wth 0/I nterfaces% ncludn" .arc ndreesen% who developed the popular 0/Ibrowser .osac for 5$ *e released an alpha verson of hs browser n >=% and n >? formed

.osac Communcatons% whch later became etscape Communcatons Corporaton$ -y >7unversty students were usn" .osac and etscape browsers to surf the 2eb on a daly bass$t about ths tme the /S "overnment be"an to transfer the control of the Internet bac!bone toprvate carrers$ Companes b" and small be"an to operate 2eb servers and transactcommerce over the 2eb$ In >B .crosoft "ot nto the 2eb busness n a b" way% and n thelate >;s t was sued for ma!n" ts browser a central component of ts operatn" system$ In>> there were over twomllon 2eb servers n operaton$ nd all of ths happened n less thanten yearsR

Durn" the >;4s% networ!n" research and development also made s"nfcant advances n theareas of h"hspeed routers and routn" (see% e$"$% Chapter ?) and local area networ!s (see% e$"$%

Chapter 7)$ The techncal communty stru""led wth the problems of defnn" and mplementn"an Internet servce model for traffc reurn" realtme constrants% such as contnuous medaapplcatons (see% e$"$% Chapter B)$ The need to secure and mana"e Internet nfrastructure (see$e$"$% Chapter H and J) also became of paramount mportance as ecommerce applcatonsprolferated and the Internet became a central component of the world4s telecommuncatonsnfrastructure$

!e%erences

Two ece!!ent iscussions o+ the history o+ the &nternet are Ho""es 1O an *einer 1O.

6Abramson %1378$ bramson% The loha System nother lternatve for Computer

Communcatons% Proceedn"s of ,all Eont Computer Conference% ,IPS Conference% H;%p$=H$6Baran %1298 P$ -aran% #On Dstrbuted Communcaton etwor!s%#IEEE Transactions onCommunication Systems,.arch% B?$ 1and Corporaton Techncal reportwth the same ttle(.emorandum 1.=?6;P1% B?)$6Berners0Lee %118 Tm -erners'ee% C+1% #Informaton .ana"ement: Proposal%# .archJ>% .ay >;6Bush %19;89$ -ush% #s 2e .ay Thn!%# The tlantc .onthly% Euly ?7$6erf %13989$ Cerf and 1$ Uahn% # protocol for pac!et networ! nterconnecton%# I+++Transactons on Communcatons Technolo"y% 9ol$ CO.66% umber 7 (.ay H?) % pp$ B6HB?;$*obbes >J 1$ *obbes Xa!on% #*obbes Internet Tmelne#% 9erson =$=% >J$6)raser %1


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Conference%n Computer Communcaton 1evew% vol$


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+arler% computers were only used as standalone machnes$ Computer networ!s were created toestablsh a communcaton ln! between dfferent users wthn an or"an3aton$ The dvanced1esearch Projects "ency (1P) des"ned dvanced 1esearch Projects "ency etwor!(1P+T) for /nted States Department of Defense$ It was the foremost computer networ! nthe /nverse$

Small computers were used to mana"e communcaton ln!s$ These small computers wereconnected to lar"e manframe computers$ These lar"e computers were connected to the1P+T$ The purpose of A'PAN5Twas that each computer would be connected to aspecal3ed computer% called as Interface .essa"e Processes (I.P)$ The I.Ps perform the storeand forward of data and were connected to each other usn" modems$

In B>% the frst 1P+T ln! was establshed between the I.P nodes at the /nversty ofCalforna at 'os n"eles (/C')$ Then Dou"las +n"elbart4s hyperte8tproject computer atStanford 1esearch Insttute (SP was connected to I.P node$ -y the end of the year% thecomputers at the /nversty of Calforna% Santa -arbara (/CS-) and the /nversty of /tah

were connected to the networ!$ ll the computers n the networ! were usn" dfferent operatn"systems and were able communcate wth each other across the networ!$

1P+T was or"nally developed for provdn" lon"dstance (remote) computn"$ 1emotecomputn" was done by a utlty pro"ram !nown as Telnet whch allows the user on onecomputer to connect to another computer on a networ!$ Telnet servce can be used for debate%dscusson and news sharn" by the news y dscusson "roups$ Stll the remote computn" sconsdered as an effectve and useful servce of the P1+T$

,le transfer s another servce provded by AP'AN5T$ It allows the users to access remotecomputer and retreve pro"rams or data$ The ,le Transfer Protocol (,TP) s utlty software

whch s used for uploadn" and downloadn" fles$ /sn" ,TP% the drectores or folders onremote computers can be easly accessed and tes can be transferred between computers$

In H;s% the research nsttutes and laboratores supported by the Department of Defense werealso ncluded n 1P+T% n varous parts of /S$

Types of Computer etwor!s

Computer networ! can be wred or wreless$ etwor!s can be cate"or3ed as per the"eo"raphcal area to be covered by the networ!$ Computer networ! ncludes 'ocal reaetwor! (')% Campus rea etwor! (C)% .etropoltan rea etwor! (.) and 2de

rea etwor! (2)

Computer networ!s for the home and small busness can be bult usn" ether wred or wrelesstechnolo"y$ 2red +thernethas been the tradtonal choce n homes% but 2,wrelesstechnolo"es are "ann" "round fast$ -oth wred and wreless can clam advanta"es over theother both represent vable optons for home and otherlocal area networ!s ('s)$
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-elow we compare wred and wreless networ!n" n fve !ey areas:

ease of nstallaton

total cost

Z relablty

Z performance

Z securty

A(out #ired LANs

Wire *)Ns use %thernet ca"!es an network aapters. )!though two computers can "e irect!y

wire to each other using an %thernet crosso-er ca"!e> wire *)Ns genera!!y a!so reAuire

centra! e-ices !ike hu"s> switches>or routersto accommoate more computers.

,or dalup connectons to the Internet% the computer hostn" the modemmust runInternetConnecton Sharn"or smlar software to share the connecton wth all other computers on the'$ -roadband routersallow easer sharn" of cable modem or DS' Internet connectons% plusthey often nclude bultn frewallsupport$

Installation

%thernet ca"!es must "e run +rom each computer to another computer or to the centra! e-ice. &t

can "e time9consuming an i++icu!t to run ca"!es uner the +!oor or through wa!!s> especia!!y

when computers sit in i++erent rooms. 'ome newer homes are pre9wire with C)T#ca"!e>

great!y simp!i+ying the ca"!ing process an minimi0ing unsight!y ca"!e runs.

The correct cabln" conf"uraton for a wred ' vares dependn" on the m8 of devces% thetype of Internet connecton% and whether nternal or e8ternal modemsare used$ *owever% none ofthese optons pose any more dffculty than% for e8ample% wrn" a home theater system$

fter hardware nstallaton% the remann" steps n conf"urn" ether wred or wreless 's donot dffer much$ -oth rely on standard Internet Protocoland networ! operatn" systemconf"uraton optons$ 'aptops and other portable devces often enjoy "reater mobilit$nwreless home networ! nstallatons (at least for as lon" as ther batteres allow)$

Cost

%thernet ca"!es> hu"s an switches are -ery inepensi-e. 'ome connection sharing so+tware

packages> !ike &C'> are +reeL some cost a nomina! +ee. roa"an routers cost more> "ut these

are optiona! components o+ a wire *)N> an their higher cost is o++set "y the "ene+it o+ easier

insta!!ation an "ui!t9in security +eatures.
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!elia(ility

%thernet ca"!es> hu"s an switches are etreme!y re!ia"!e> main!y "ecause manu+acturers ha-e

"een continua!!y impro-ing %thernet techno!ogy o-er se-era! ecaes. *oose ca"!es !ike!y

remain the sing!e most common an annoying source o+ +ai!ure in a wire network. When

insta!!ing a wire *)N or mo-ing any o+ the components !ater> "e sure to care+u!!y check the

ca"!e connections.

-roadband routers have also suffered from some relablty problems n the past$ /nl!e other+thernet "ear% these products are relatvely new% multfuncton devces$ -roadband routers havematured over the past several years and ther relablty has mproved "reatly$

Per%or&ance

Wire *)Ns o++er superior per+ormance. Traitiona! %thernet connections o++er on!y 17 M"ps

"anwith> "ut 177 M"ps 6ast %thernet techno!ogy costs !itt!e more an is reai!y a-ai!a"!e.

)!though 177 M"ps represents a theoretica! maimum per+ormance ne-er rea!!y achie-e in

practice> 6ast %thernet shou! "e su++icient +or home +i!e sharing> gaming> an high9spee&nternet access +or many years into the +uture.

2red 's utl3n" hubs can suffer performance slowdown f computers heavly utl3e thenetwor! smultaneously$ /se +thernet swtches nstead of hubs to avod ths problem a swtchcosts lttle more than a hub$

Security

6or any wire *)N connecte to the &nternet> +irewa!!s are the primary security

consieration. Wire %thernet hu"s an switches o not support +irewa!!s. Howe-er>

+irewa!! so+tware proucts !ike Jone)!armcan "e insta!!e on the computers themse!-es.

roa"an routers o++er eAui-a!ent +irewa!! capa"i!ity "ui!t into the e-ice> con+igura"!e

through its own so+tware.

A(out #ireless LANs

Popu!ar W*)N techno!ogies a!! +o!!ow one o+ the three main Wi96icommunication stanars.

The "ene+its o+ wire!ess networking epen on the stanar emp!oye

72.11"was the +irst stanar to "e wie!y use in W*)Ns.

The 72.11astanar is +aster "ut more epensi-e than 72.11"L 72.11a is more

common!y +oun in "usiness networks.

The newest stanar> 72.11g> attempts to com"ine the "est o+ "oth 72.11a an

72.11"> though it too is more a more epensi-e home networking option.

Installation

Wi96i networks can "e con+igure in two i++erent ways
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D) hocD moe a!!ows wire!ess e-ices to communicate in peer9to9peer moe with each

other. D&n+rastructureD moe a!!ows wire!ess e-ices to communicate with a centra! noe that in

turn can communicate with wire noes on that *)N.

.ost 's reure nfrastructure mode to access the Internet% a local prnter% or other wredservces% whereas ad hoc mode supports only basc fle sharn" between wreless devces$

-oth 2, modes reure wreless networ! adapters% sometmes called 2' cards$Infrastructure mode 2's addtonally reure a central devce called the access pont$ Theaccess pont must be nstalled n a central locaton where wreless rado s"nals can reach t wthmnmal nterference$ lthou"h 2, s"nals typcally reach wire!ess aapters an access points may cost three or +our times as much as %thernetca"!e aapters an hu"s8switches> respecti-e!y. 72.11" proucts ha-e roppe in price

consiera"!y with the re!ease o+ 72.11g> an o"-ious!y> "argain sa!es can "e +oun i+ shoppers

are persistent.

!elia(ility

Wire!ess *)Ns su++er a +ew more re!ia"i!ity pro"!ems than wire *)Ns> though perhaps not

enough to "e a signi+icant concern. 72.11" an 72.11g wire!ess signa!s are su"ject to

inter+erence +rom other home app!icances inc!uing microwa-e o-ens> cor!ess te!ephones> an

garage oor openers. With care+u! insta!!ation> the !ike!ihoo o+ inter+erence can "e minimi0e.

2reless networ!n" products% partcularly those that mplement J;6$

that is approimate!y one9ha!+ the "anwith o+ 6ast %thernet. 6urthermore> Wi96i per+ormance

is istance sensiti-e> meaning that maimum per+ormance wi!! egrae on computers +arther

away +rom the access point or other communication enpoint. )s more wire!ess e-ices uti!i0e

the W*)N more hea-i!y> per+ormance egraes e-en +urther.

Overall% the performance of J;6$


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must sometmes be ted to an electrcal cord and outlet for power$ Ths undermnes the mobltyadvanta"e of 2's n many homes$

Security

&n theory> wire!ess *)Ns are !ess secure than wire *)Ns> "ecause wire!ess communication

signa!s tra-e! through the air an can easi!y "e intercepte. To pro-e their point> someengineers ha-e promote the practice o+warri-ing> that in-o!-es tra-e!ing through a resientia!

area with Wi96i eAuipment scanning the airwa-es +or unprotecte W*)Ns. /n "a!ance> though>

the weaknesses o+ wire!ess security are more theoretica! than practica!. W*)Ns protect their

ata through the Wire %Aui-a!ent Pri-acy :W%P;encryption stanar> that makes wire!ess

communications reasona"!y as sa+e as wire ones in homes.

o computer networ! s completely secure and homeowners should research ths topc to ensurethey are aware of and comfortable wth the rs!s$ Important securty consderatons forhomeowners tend to not be related to whether the networ! s wred or wreless but ratherensurn":

the homeBs &nternet +irewa!! is proper!y con+igure

the +ami!y is +ami!iar with the anger o+ &nternet Dspoo+ emai!sD an how to recogni0e

them

the +ami!y is +ami!iar with the concept o+ DspywareD an how to a-oi it

"a"ysitters> housekeepers an other -isitors o not ha-e unwante access to the

network

Conclusion

ouB-e stuie the ana!ysis an are reay to make your ecision. ottom !ine> then> which is"etter 9 wire or wire!essE The ta"!e "e!ow summari0es the main criteria weB-e consiere in

this artic!e. &+ you are -ery cost9conscious> nee maimum per+ormance o+ your home system>

an onBt care much a"out mo"i!ity> then a wire %thernet *)N is pro"a"!y right +or you.

If on the other hand% cost s less of an ssue% you l!e ben" an early adopter of leadn"ed"etechnolo"es% and you are really concerned about the tas! of wrn" your home or small busnesswth +thernet cable% then you should certanly consder a wreless '$

.any of you wll naturally fall somewhere n between these two e8tremes$ If you4re stllundecded% consder as!n" frends and famly about ther e8perences wth buldn" 's$ nd%

spend just a few more mnutes wth our nteractve -ome Network Ad(isortool$ It should helpyou decde on the type of networ! as well as the "ear you wll want to have$

0ve t a try: *ome etwor! dvsor

*ired (s *ireless
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Wire Wire!ess

Installationmoerate

i++icu!ty

easier> "ut "eware

inter+erence

Cost !ess more

*eliability high reasona"!y high

Performanc

e-ery goo goo

Security reasona"!y goo reasona"!y goo

+obility !imite outstaning

Characterstcs of a Computer etwor!

The prmary purpose of a computer networ! s to share resources:

ou can play a CD musc from one computer whle sttn" on another computer

ou may have a computer that doesn[t have a D9D or -lu1ay (-D) player$ In ths case%

you can place a move dsc (D9D or -D) on the computer that has the player% and thenvew the move on a computer that lac!s the player

ou may have a computer wth a CD&D9D&-D wrter or a bac!up system but the other

computer(s) doesn[t (don4t) have t$ In ths case% you can burn dscs or ma!e bac!ups on a

computer that has one of these but usn" data from a computer that doesn[t have a dscwrter or a bac!up system

ou can connect a prnter (or a scanner% or a fa8 machne) to one computer and let other

computers of the networ! prnt (or scan% or fa8) to that prnter (or scanner% or fa8machne)

ou can place a dsc wth pctures on one computer and let other computers access those

pctures

ou can create fles and store them n one computer% then access those fles from the

other computer(s) connected to t

Characteristics of a Computer Network

The primary purpose o+ a computer network is to share resources

ou can p!ay a C< music +rom one computer whi!e sitting on another computer

ou may ha-e a computer with a C< writer or a "ackup system "ut the othercomputer oesnQt ha-e itL &n this case> you can "urn C


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computer that has one o+ these "ut using ata +rom a computer that oesnQt ha-e a C

=ni-ersity o+ Ca!i+ornia at 'anta ar"ara>an the =ni-ersity o+ =tahwere connecte asthe "eginning o+ the )5P)N%Tnetwork using #7 k"it8s circuits.4O

Commercia! ser-ices using?.2#were ep!oye in 12> an !ater use as an uner!ying

in+rastructure +or epaning TCP8&Pnetworks.

Today% computer networ!s are the core of modern communcaton$ ll modern aspects of thepublc swtched telephone networ!(PST) are computercontrolled% and telephony ncreasn"lyruns over the Internet Protocol% althou"h not necessarly the publc Internet$ The scope ofcommuncaton has ncreased s"nfcantly n the past decade% and ths boom n communcatonswould not have been possble wthout the pro"ressvely advancn" computer networ!$ Computernetwor!s% and the technolo"es needed to connect and communcate throu"h and between them%contnue to drve computer hardware% software% and perpherals ndustres$ Ths e8panson smrrored by "rowth n the numbers and types of users of networ!s% from the researcher to thehome user$

Interconnected collecton of autonomous computers(unue dentty) s !nown as computer

networ!$

Pro#erties

Computer networ!s:

6aci!itate communications

=sing a network> peop!e can communicate e++icient!y an easi!y -ia emai!> instant

messaging> chat rooms> te!ephone> -ieo te!ephone ca!!s> an -ieo con+erencing.

Permit sharing o+ +i!es> ata> an other types o+ in+ormation

&n a network en-ironment> authori0e users may access ata an in+ormation store on

other computers on the network. The capa"i!ity o+ pro-iing access to ata an

in+ormation on share storage e-ices is an important +eature o+ many networks.

'hare network an computing resources
http://en.wikipedia.org/wiki/Leonard_Kleinrockhttp://en.wikipedia.org/wiki/Paul_Baranhttp://en.wikipedia.org/wiki/Paul_Baranhttp://en.wikipedia.org/wiki/Donald_Davieshttp://en.wikipedia.org/wiki/Packet_(information_technology)http://en.wikipedia.org/w/index.php?title=Thomas_Marill_(scientist)&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Thomas_Marill_(scientist)&action=edit&redlink=1http://en.wikipedia.org/wiki/Lawrence_G._Robertshttp://en.wikipedia.org/wiki/Wide_area_networkhttp://en.wikipedia.org/wiki/Wide_area_networkhttp://en.wikipedia.org/wiki/ARPANEThttp://en.wikipedia.org/wiki/Telephone_switchhttp://en.wikipedia.org/wiki/Telephone_switchhttp://en.wikipedia.org/wiki/Western_Electrichttp://en.wikipedia.org/wiki/University_of_California_at_Los_Angeleshttp://en.wikipedia.org/wiki/Stanford_Research_Institutehttp://en.wikipedia.org/wiki/Stanford_Research_Institutehttp://en.wikipedia.org/wiki/University_of_California_at_Santa_Barbarahttp://en.wikipedia.org/wiki/University_of_California_at_Santa_Barbarahttp://en.wikipedia.org/wiki/University_of_Utahhttp://en.wikipedia.org/wiki/ARPANEThttp://en.wikipedia.org/wiki/Computer_network#cite_note-3http://en.wikipedia.org/wiki/X.25http://en.wikipedia.org/wiki/X.25http://en.wikipedia.org/wiki/TCP/IPhttp://en.wikipedia.org/wiki/Public_switched_telephone_networkhttp://en.wikipedia.org/wiki/Leonard_Kleinrockhttp://en.wikipedia.org/wiki/Paul_Baranhttp://en.wikipedia.org/wiki/Donald_Davieshttp://en.wikipedia.org/wiki/Packet_(information_technology)http://en.wikipedia.org/w/index.php?title=Thomas_Marill_(scientist)&action=edit&redlink=1http://en.wikipedia.org/wiki/Lawrence_G._Robertshttp://en.wikipedia.org/wiki/Wide_area_networkhttp://en.wikipedia.org/wiki/ARPANEThttp://en.wikipedia.org/wiki/Telephone_switchhttp://en.wikipedia.org/wiki/Western_Electrichttp://en.wikipedia.org/wiki/University_of_California_at_Los_Angeleshttp://en.wikipedia.org/wiki/Stanford_Research_Institutehttp://en.wikipedia.org/wiki/University_of_California_at_Santa_Barbarahttp://en.wikipedia.org/wiki/University_of_Utahhttp://en.wikipedia.org/wiki/ARPANEThttp://en.wikipedia.org/wiki/Computer_network#cite_note-3http://en.wikipedia.org/wiki/X.25http://en.wikipedia.org/wiki/TCP/IPhttp://en.wikipedia.org/wiki/Public_switched_telephone_network


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&n a networke en-ironment> each computer on a network may access an use

resources pro-ie "y e-ices on the network> such as printing a ocument on a share

network printer. or to pre-ent these e-ices +rom

norma!!y accessing the network :enia! o+ ser-ice;.

May inter+ere with other techno!ogies

Power !ine communicationstrong!y istur"s certain #O+orms o+ raio communication> e.g.>

amateur raio.(O&t may a!so inter+ere with !ast mi!eaccess techno!ogies such as )


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two +orms unshie!e twiste pair :=TP; an shie!e twiste9pair :'TP;. %ach +ormcomes in se-era! category ratings> esigne +or use in -arious scenarios.

'oa0ial cable is wie!y use +or ca"!e te!e-ision systems> o++ice "ui!ings> an other

work9sites +or !oca! area networks. The ca"!es consist o+ copper or a!uminum wiresurroune "y an insu!ating !ayer :typica!!y a +!ei"!e materia! with a high ie!ectric

constant;> which itse!+ is surroune "y a conucti-e !ayer. The insu!ation he!ps minimi0einter+erence an istortion. Transmission spee ranges +rom 277 mi!!ion "its per seconto more than #77 mi!!ion "its per secon.

&T=9T @.hntechno!ogy uses eisting home wiring:coaia! ca"!e> phone !ines anpower

!ines; to create a high9spee :up to 1 @iga"it8s; !oca! area network.

)noptica! +i"eris a g!ass +i"er. &t uses pu!ses o+ !ight to transmit ata. 'ome a-antages

o+ optica! +i"ers o-er meta! wires are !ess transmission !oss> immunity +rome!ectromagnetic raiation> an -ery +ast transmission spee> up to tri!!ions o+ "its persecon. /ne can use i++erent co!ors o+ !ights to increase the num"er o+ messages "eingsent o-er a +i"er optic ca"!e.

#ireless technolo'ies

/errestrialmicrowaveR Terrestria! microwa-e communication uses %arth9"ase

transmitters an recei-ers resem"!ing sate!!ite ishes. Terrestria! microwa-es are in the!ow9gigahert0 range> which !imits a!! communications to !ine9o+9sight. 5e!ay stations arespace approimate!y 4 km :37 mi; apart.

'ommunications satellitesR The sate!!ites communicate -ia microwa-e raio wa-es>

which are not e+!ecte "y the %arthBs atmosphere. The sate!!ites are statione in space>typica!!y in geosynchronous or"it 3#>477 km :22>777 mi; a"o-e the eAuator. These%arth9or"iting systems are capa"!e o+ recei-ing an re!aying -oice> ata> an T, signa!s.

'ellular an P'# systemsuse se-era! raio communications techno!ogies. The systems

i-ie the region co-ere into mu!tip!e geographic areas. %ach area has a !ow9powertransmitter or raio re!ay antenna e-ice to re!ay ca!!s +rom one area to the net area.

Raio an sprea spectrum technologiesR Wire!ess !oca! area network use a high9

+reAuency raio techno!ogy simi!ar to igita! ce!!u!ar an a !ow9+reAuency raiotechno!ogy. Wire!ess *)Ns use sprea spectrum techno!ogy to ena"!e communication"etween mu!tip!e e-ices in a !imite area. &%%% 72.11e+ines a common +!a-or o+open9stanars wire!ess raio9wa-e techno!ogy.

&n+rare communication can transmit signa!s +or sma!! istances> typica!!y no more than17 meters. &n most cases> !ine9o+9sight propagationis use> which !imits the physica!positioning o+ communicating e-ices.

)g!o"a! area network:@)N; is a network use +or supporting mo"i!e across an ar"itrary

num"er o+ wire!ess *)Ns> sate!!ite co-erage areas> etc. The key cha!!enge in mo"i!ecommunications is haning o++ user communications +rom one !oca! co-erage area to thenet. &n &%%% Project 72> this in-o!-es a succession o+ terrestria! wire!ess *)Ns.O
http://en.wikipedia.org/wiki/Coaxial_cablehttp://en.wikipedia.org/wiki/ITU-Thttp://en.wikipedia.org/wiki/G.hnhttp://en.wikipedia.org/wiki/Home_wiringhttp://en.wikipedia.org/wiki/Home_wiringhttp://en.wikipedia.org/wiki/Ethernet_over_coaxhttp://en.wikipedia.org/wiki/Power_line_communicationhttp://en.wikipedia.org/wiki/Power_line_communicationhttp://en.wikipedia.org/wiki/Power_line_communicationhttp://en.wikipedia.org/wiki/Optical_fiberhttp://en.wikipedia.org/wiki/Optical_fiberhttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Satellitehttp://en.wikipedia.org/wiki/IEEE_802.11http://en.wikipedia.org/wiki/Infrared_communicationhttp://en.wikipedia.org/wiki/Line-of-sight_propagationhttp://en.wikipedia.org/wiki/Global_area_networkhttp://en.wikipedia.org/wiki/Global_area_networkhttp://en.wikipedia.org/wiki/Wireless_LANhttp://en.wikipedia.org/wiki/Computer_network#cite_note-7http://en.wikipedia.org/wiki/Computer_network#cite_note-7http://en.wikipedia.org/wiki/Coaxial_cablehttp://en.wikipedia.org/wiki/ITU-Thttp://en.wikipedia.org/wiki/G.hnhttp://en.wikipedia.org/wiki/Home_wiringhttp://en.wikipedia.org/wiki/Ethernet_over_coaxhttp://en.wikipedia.org/wiki/Power_line_communicationhttp://en.wikipedia.org/wiki/Power_line_communicationhttp://en.wikipedia.org/wiki/Optical_fiberhttp://en.wikipedia.org/wiki/Microwavehttp://en.wikipedia.org/wiki/Satellitehttp://en.wikipedia.org/wiki/IEEE_802.11http://en.wikipedia.org/wiki/Infrared_communicationhttp://en.wikipedia.org/wiki/Line-of-sight_propagationhttp://en.wikipedia.org/wiki/Global_area_networkhttp://en.wikipedia.org/wiki/Wireless_LANhttp://en.wikipedia.org/wiki/Computer_network#cite_note-7


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4otic technolo'ies

There have been varous attempts at transportn" data over more or less e8otc meda:

&P o-er )-ian Carrierswas a humorous )pri! +oo!Bs 5eAuest +or Comments> issue as

*!C ##0%. &t was imp!emente in rea! !i+e in 2771.O

%tening the &nternet to interp!anetary imensions -ia raio wa-es. 17O

-oth cases have a lar"eroundtrp delay tme% whch prevents useful communcaton$

ommunications #rotocols and network #rogramming

&nternetmap. The &nternet is a g!o"a! system o+ interconnecte computer networks that use the

stanar &nternet Protoco! 'uite:TCP8&P; to ser-e "i!!ions o+ users wor!wie.

Main artic!e Communications protoco!

communcatons protocol s a set of rules for e8chan"n" nformaton over a networ!$ It stypcally aprotocol stac!(also see the OSI model)% whch s a #stac!# of protocols% n whch eachprotocol uses the protocol below t$ n mportant e8ample of a protocol stac! s *TTPrunnn"over TCPover IPover I+++ J;6$


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thernet

Main artic!e %thernet

+thernet s a famly of protocols used n 's% descrbed by a set of standards to"ether calledI+++ J;6publshed by the Insttute of +lectrcal and +lectroncs +n"neers$ It has a flat

addressn" scheme and s mostly stuated at levels < and 6 of the OSI model$ ,or home userstoday% the most well!nown member of ths protocol famly s I+++ J;6$


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orentedmodel n whch a vrtual crcutmust be establshed between two endponts before theactual data e8chan"e be"ns$

2hle the role of T. s dmnshn" n favor of ne8t"eneraton networ!s% t stll plays a role nthe last mle% whch s the connecton between anInternet servce provderand the home user$

,or an nterestn" wrteup of the technolo"es nvolved% ncludn" the deep stac!n" ofcommuncatons protocols used% see$


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Wie :W)N;

&nternet

&nterp!anetary &nternet

-

t

e

etwor!s are often classfed by ther physcal or or"an3atonal e8tent or ther purpose$ /sa"e%trust level% and access r"hts dffer between these types of networ!s$

Personal area network

personal area networ!(P) s a computer networ! used for communcaton amon" computerand dfferent nformaton technolo"cal devces close to one person$ Some e8amples of devcesthat are used n a P are personal computers% prnters% fa8 machnes% telephones% PDs%scanners% and even vdeo "ame consoles$ P may nclude wred and wreless devces$ Thereach of a P typcally e8tends to


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Typica! !i"rary network> in a "ranching tree topo!ogy an contro!!e access to resources

sample ' s depcted n the accompanyn" da"ram$ ll nterconnected devces mustunderstand the networ! layer (layer =)% because they are handln" multple subnets (the dfferentcolors)$ Those nsde the lbrary% whch have only


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6ack(one network

bac!bone networ!s part of a computer networ! nfrastructure that nterconnects varouspeces of networ!% provdn" a path for the e8chan"e of nformaton between dfferent 's orsubnetwor!s$ bac!bone can te to"ether dverse networ!s n the same buldn"% n dfferent

buldn"s n a campus envronment% or over wde areas$ ormally% the bac!bone4s capacty s"reater than that of the networ!s connected to t$

lar"e corporaton whch has many locatons may have a bac!bone networ! that tes all of theselocatons to"ether% for e8ample% f a server cluster needs to be accessed by dfferent departmentsof a company whch are located at dfferent "eo"raphcal locatons$ The eupment whch testhese departments to"ether consttute the networ! bac!bone$etwor! performance mana"ementncludn" networ! con"estonare crtcal parameters ta!en nto account when des"nn" anetwor! bac!bone$

specfc case of a bac!bone networ! s the Internet bac!bone%whch s the set of wdearea

networ! connectons and core routersthat nterconnect all networ!s connected to the Internet$

5etropolitan area network

.etropoltan area networ!(.) s a lar"e computer networ! that usually spans a cty or alar"e campus$

'amp!e %PN mae o+ 6rame re!ayW)N connections an ia!up remote access.
http://en.wikipedia.org/wiki/Backbone_networkhttp://en.wikipedia.org/wiki/Network_performance_managementhttp://en.wikipedia.org/wiki/Network_congestionhttp://en.wikipedia.org/wiki/Internet_backbonehttp://en.wikipedia.org/wiki/Internet_backbonehttp://en.wikipedia.org/wiki/Core_routerhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Metropolitan_area_networkhttp://en.wikipedia.org/wiki/Frame_relayhttp://en.wikipedia.org/wiki/File:EPN_Frame-Relay_and_Dial-up_Network.svghttp://en.wikipedia.org/w/index.php?title=File:EPN_Frame-Relay_and_Dial-up_Network.svg&page=1http://en.wikipedia.org/wiki/Backbone_networkhttp://en.wikipedia.org/wiki/Network_performance_managementhttp://en.wikipedia.org/wiki/Network_congestionhttp://en.wikipedia.org/wiki/Internet_backbonehttp://en.wikipedia.org/wiki/Core_routerhttp://en.wikipedia.org/wiki/Internethttp://en.wikipedia.org/wiki/Metropolitan_area_networkhttp://en.wikipedia.org/wiki/Frame_relay


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'amp!e ,PN use to interconnect 3 o++ices an remote users

#ide area network

wde area networ!(2) s a computer networ! that covers a lar"e "eo"raphc area such as acty% country% or spans even ntercontnental dstances% usn" a communcatons channel thatcombnes many types of meda such as telephone lnes% cables% and ar waves$ 2 oftenuses transmsson facltes provded by common carrers% such as telephone companes$ 2technolo"es "enerally functon at the lower three layers of the OSI reference model: thephyscallayer% the data ln! layer%and the networ! layer$

nterprise pri7ate network

n enterprse prvate networ!s a networ! bult by an enterprse to nterconnect varouscompany stes% e$"$% producton stes% head offces% remote offces% shops% n order to sharecomputer resources$

8irtual pri7ate network

vrtual prvate networ!(9P) s a computer networ! n whch some of the ln!s betweennodes are carred by open connectons or vrtual crcuts n some lar"er networ! (e$"$% theInternet) nstead of by physcal wres$ The data ln! layer protocols of the vrtual networ! aresad to be tunneled throu"h the lar"er networ! when ths s the case$ One common applcaton s

secure communcatons throu"h the publc Internet% but a 9P need not have e8plct securtyfeatures% such as authentcaton or content encrypton$ 9Ps% for e8ample% can be used toseparate the traffc of dfferent user communtes over an underlyn" networ! wth stron"securty features$

9P may have besteffort performance% or may have a defned servce level a"reement (S')between the 9P customer and the 9P servce provder$ 0enerally% a 9P has a topolo"ymore comple8 than ponttopont$
http://en.wikipedia.org/wiki/Wide_area_networkhttp://en.wikipedia.org/wiki/Wide_area_networkhttp://en.wikipedia.org/wiki/OSI_modelhttp://en.wikipedia.org/wiki/Physical_layerhttp://en.wikipedia.org/wiki/Physical_layerhttp://en.wikipedia.org/wiki/Data_link_layerhttp://en.wikipedia.org/wiki/Data_link_layerhttp://en.wikipedia.org/wiki/Network_layerhttp://en.wikipedia.org/wiki/Enterprise_private_networkhttp://en.wikipedia.org/wiki/Virtual_private_networkhttp://en.wikipedia.org/wiki/File:Virtual_Private_Network_overview.svghttp://en.wikipedia.org/w/index.php?title=File:Virtual_Private_Network_overview.svg&page=1http://en.wikipedia.org/wiki/Wide_area_networkhttp://en.wikipedia.org/wiki/OSI_modelhttp://en.wikipedia.org/wiki/Physical_layerhttp://en.wikipedia.org/wiki/Physical_layerhttp://en.wikipedia.org/wiki/Data_link_layerhttp://en.wikipedia.org/wiki/Network_layerhttp://en.wikipedia.org/wiki/Enterprise_private_networkhttp://en.wikipedia.org/wiki/Virtual_private_network


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8irtual Network

ot to be confused wth a 9rtual Prvate etwor!% a 9rtual etwor! defnes data traffc flowsbetween vrtual machneswthn a hypervsorn a vrtual computn" envronment$ 9rtualetwor!s may employ vrtual securty swtches% vrtual routers%vrtual frewallsand other vrtual

networ!n" devces to drect and secure data traffc$

Internetwork

n nternetwor!s the connecton of multple computer networ!s va a common routn"technolo"y usn" routers$ The Internets an a""re"aton of many connected nternetwor!sspannn" the +arth$

@rganiational sco#e

etwor!s are typcally mana"ed by or"an3atons whch own them$ ccordn" to the owner4spont of vew% networ!s are seen as ntranets or e8tranets$ specal case of networ! s theInternet%whch has no sn"le owner but a dstnct status when seen by an or"an3atonal entty Qthat of permttn" vrtually unlmted "lobal connectvty for a "reat multtude of purposes$

Intranets and e4tranets

Intranets and e8tranets are parts or e8tensons of a computer networ!% usually a '$

n ntranets a set of networ!s% usn" theInternet Protocoland IPbased tools such as webbrowsers and fle transfer applcatons% that s under the control of a sn"le admnstratve entty$

That admnstratve entty closes the ntranet to all but specfc% author3ed users$ .ostcommonly% an ntranet s the nternal networ! of an or"an3aton$ lar"e ntranet wll typcallyhave at least one web server t

net working project

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