Computer Networks Data link layer and Network layer

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    MAILAM ENGINEERING COLLEOEDEPARTMENT OF INFORI\/TA'IION TECHNOLbGYC52302 Canpter Netuals / trUIIIT trPAR'T.B

    Medlum acces6 CsMA-ErheDet-,tok.n ring-FDDl-Wireless L"AN-BrdAes an I1. h.plai IllediuE &c6s L.yci proto@ts tn d6t x. Whe nodes or stations de cotuectd md use a @I4on lirk, calle(la multipoint oi broadcast 1ink, we nee.t a mldtiple-ecess protocol n,coordinate access to the link

    TAXONOMY OF MUA''IPLE ACCESS PRC)iIOCO],S

    I

    -1r iRA {DOM ACCESS' In rddom access or contention betho.ls, no stauon is superioi l,eother station md none is aEsignd to coDtrol over arother.. No station pcmits, or does not per@it dotne. station ro se..tr@ Fedilares ofta iron A@as' There is no schduled time for a sration ro hosmit as ihe nM,implies. No tules speciry which statio. shoutd scnd n*r.. Stations iight with one eotler to acce6s tlte @dih bv a metn.,c.lled contenrion methods.tefe' IEEE ao2.O@rnetuet), rEEE 8o2.sgoken Riog).FDDI,rEEE 802.1l(wireless LAN) MAC Layer

    PEparal by S.Kalaiv&y A /rR.Odendim A /rT

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    MAI],AM ENGINEERING COLLEGEDEPARTMENT OF INFORMAT1ON TECHNOLOGYC52302 Conputer Networks / nEtplain cardci s.Be Uultiplc Acces6 (csMA) tn d.tril. T o ,ninimiu th. chdce of conision dd iacrease the performance

    CSI{A method @s developed,' The chae of @lision cd be reduced iI a station senses fie mediuma@ess (CSMA) requires that each station irst(or check the state of the medium) beiore

    In othe wolds, CSMA is based on the principle 4sense beloretransmit' oi 4listen before talk.CS\IA can reduce th possibility oI collision, but it cannot elimiDte it.

    before tying to use it.. cdrier sensc multiplelisten to the medilm

    r.eldd y S.Kalai@y APmR.GajmAimAlm

    S,d.e/ttrB tualel olth. colllalon ln CSMAAt lime tI, station B *nses the medium and fiads it idle, so it sends aAt rime t2 (t2>t1), station c senses the medim dd finds it ldlebecause, at this tir., thc lirst bits lrcm station B have not leachedStarion C also Bends a trme-The @ signals collide dd bolh frmes @ destroyed.

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    MAILAM ENGINEERING COLLEGEDEPARTMENT OF INFORMATTON TECHNOLOGYCS23O2 Can )ter Nerra c/Vtlneruble rTme

    PersiBtence Metnods:

    Therulnerable time lor CSMA is the plopagation time Tp_This is t]le time needed Ior a signa.l to plopagate trom o.e end ot tn(When a station sads a frme, m.l dy other staft. Eies lo se..l .frsmc dunnC $is ihe, a .oUision wiIIEsulr

    :: ln;L:i.HiiE;ir',i:;,3l..;&*i

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    MAILAM ENCINEERING COLLEGEDEPARIMENT OF INFPRMATION TECHNOLOGYCS23O2 Conlpicr Neh,orks / rB.haoior ofth@ pe$ist ^n ',.athods

    ' Thc l-peEisteit othod is sioplc 6d 6baightfo dd.. In this method, alter thc staiion linds the line idle, it sends its frameimediately (with prcbabiliry 1).. This method has the highest chd$ of colision because two or morestations @y fmd thc lin. idle and Be.d their flEEes immediately.

    . ln the aonpersistdt method, a station tlEt has a fraf,e ro sendseftes the lin -

    ' The noopersistcnt appro4h reduces the chmce of collision because itis unlikly that two or more stations will wait the sme mount oftim. and ct y to s6d simultaneously.

    . The p-peisistent method is used if the chMel has time slots with slotduration equal to or greater thd the maximm Prcp.gatio. tim.. ahe p-psist nt app.osch cdbiDes the adEtsges oI the other nto

    . lt redues f-he chdce of @Ihion od impr@es eflciency.Ii lhis mEthod, aft.r th. .tation fhds the line idle it follows these steps:,/ with prcbabilit p, the station s6als its ftahe-./ With prcbability q-l-p, the .tation waits for the beginning of the nsttlmc slot sd ch.ckb thc lif,e amin,

    r th. liie is iauc, it s@ds imcdiately.lf the lif,e is not idle, it mits a rddoE @ount or time sd then*n6es the line aeain.

    . If the line is idle, it goes to step 1 ,. lf tlE liEe is buq., it acts as though a colision has occufed anduss the backor prccedure.

    Iyepaed b S.Kalaivey A?mR.GajodimA}m

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    MA]T,\M ENGINEDRING COLLEGEDEPAMMENT OF INFORMATION TECIINOLbOYwry"te|;'r4-?,#/

    :c:l.l1A49P birs the stanon what to do whcn a corusion is detecte.csMA/cA tries to avoid the collisiotr.Carrler s.ns. M tt'ipt Acc.ss u,tth anukton Ddi.ctiot TCSMA/,D,hulripte e.(ess with coliision aeteirt"n rbsti_qlco.ugrenis Lhe a.lsorirhm to nedt. ue coliision,

    . A sra.ion aonirors lhe mediLtu aJrcr ir sen.ls a ree ro seF it thttusmission was successfld.. Ifso, the station is jidishe.l. It however, there is a couision, rhe irani

    collision ot the first bitjn csMA/cDAt time 11, station A has executed itssending the bits of its f ?me,Prcpeed by S.Kalaivey AI/[IR.oaj@dim Alm -5-

    persistence procedue and stail

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    lrt^lma Ftcru Slb,. For CSMA/CD to work, ft n@d a restlicrion on the fEme sire.. Befole sandina thc last bit of the frme, the *nding station mustdelect s coUisi@, if 6y, dd abon rhF Edsmission,. This is $ becaEc the station, once the entiE frme is sent, does notkeep a copy of the Ame dd do.s not monitor &e line for collisiondeiection. Theefoie, the AMe trdsmission time T must be at Ieasttwo times f-tre ndinh prcpagation time Tp,

    r\ nehDrk using CSMA/CD has a bdndwidth of 10 Mbps.If the llBimm prcpegation time (including the delays in the devices ddiBnorinS the tiEc nedad to sehd a j@ing sigftl is 25.6rs, what is theininimu sia of th. nEm.?

    MAILAM ENGINEERINC COLLFEEDEPARTMETIT OF INFORMAT1ON AECHNOLOGY'cs2io2 comtute, N"h.",k" / ffA' 'nr 12. station C has nor yer scnsed Ehe f r3t brr s;nt by A.

    Stalion C @utes its pGistence ptucedus dd stdts sending thebits in its frde, i,hich prcFagate both to the left md to the right.The colbiotr ocrys sometime a.ftd time t2.Starion C dctccts a colision at tilnp t3 when it receives the first bit ofA's ft?E..Stalion C iEmediatcly (or aJter a short tif,e, but we assumei@ediatel, aborts trusmission.Station A detecE collbion at time t4 when it receives the lirst bit of Chfarne j it also imediatcly aborts trusflissioq.Looking at the Ag@, we .m see thar A t@smits for rhe dumtion t4tl: C tldsmita for the duatio. t3 - t2.

    is Tr= 2 XTe = 51.2lls. Thisto t@smit lor a period of 51.2usotthe frme i6 10 Mbps X 51.2 sSolutior: The lrme Ea4smission rimerneas, in the mrst cas., a station needsr,, detect the @llision, The midrrE si@512 bit8 or 64 b,.ies.lr, 9 saLevelr. Lkl oI energl in a chmet cu have thrce va.lucsr Zro, nomal, dd

    . At the zlo lcv.l, the chmel is icU6.it p@d by S.Kalai6y AlmILcajodituA?m 6-

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    M ENG]NEERING COLLEGET OF INFORMATION AECHNOI.OGYt th nomal level, a starioned is sending its fr@e.

    At the abnolnDl leyel, there istwice the nomal levetA station thar has a f.de to sendmonitor the eoer6,lvel to deremine

    a collision dd rne ldel of the enerS/or is seadiag a free needs tif the chmel is idle, bust or nl

    cs2302

    Lnerry.eLel dutus uesmission, idleness or @Urs.orca -n1fr, ae :1 NitryI3. a.tce$ ollh cotfi.tton A@tdhce tcsJfv(/tt^ rr.r. Lr*. bas, ldea bphind csMA/cA i\ thEr a sauon needs ro b- dole II r-.ere whrle 'resmirlin8 ro deF(L c .ollis-on.). wlen rl-er- is ro col',sion. $e sLlion re(e-ves one 6isnal irs owj

    . When ihere is a coUision, rhe station receiv6 two signars: jts owrsignrl ed the signal tlosmitled by a 6ecoud statio .t In a wired network, the received sigMl has almost the s@e ener$r asthe sent signal because eirher the length of the cable is shon or thrtee repeaters rhat dpli8i rhe ene ry berwftn the sender an.l t , This neds that in a collision, the detecte.t energ/ alEost doubtes.. ID a wjreless network, much ot the senr energ is lost in bdsmission. The received sig@t has very linle enerry_. Therelore, a couision may ad.t only 5 to 10 percenr additiona.l eners/.. This is nor usetut lor etrective .ollision dere.tio.

    PEptred by S.(alaivoy At/tTR.cajeMnan Apm

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    MAIL"IM ENGINEERING COLLEGEDEPARTMEM OF INFORMAIION'TECI'NOIT)GYCS23O2 Coneutet Nen orks / ITTo avoid collisions on wictess networks beaus; they cannot bedeteted .sier sase Eultiple acess with coUisioravoidace

    (CSMA/CA) -as invenred fo this neEvork.Collisions e avoided rhrough the use of CSMA/CA,S three strategies:&e intd ft@e space, the contention rindow, a.t acLhowledgements.

    Tining in CSMA/CAtatcrjfttu sPa@ Its,:. First, collisions @ aaoided y delening kdshission even if thechannel is found idleWhen e idle chmel is Iourdj the station does not send imnedjatety.It saits for a periocl of tihe called the inter-frme space or IFS.Even though the chdhel may apped idle when it is sensed, Edisldce station aay have already started trEnsmitting.The distant station's signa-1 has nor yet leached this station.'lhr IFS tlme allore the front of the trdsmitted signat by the distmtstario to reach tnis station.If after the IFS time ttE chdnel is still id1e, the station cd send, butit still neeals to @it a time equal ro the contention rime.

    rlepaed by S,(daivay APmR,CojadimAPm -8

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    In CSM

    t The .oote.tion windov is A statio4 that i6 rcady to

    I"TM ENGINEERING COLLEGE ..ENT OF INFORI/IATION TECHNOLOGY. CS23A2 Computq Nddo*s _cd olso be uled rc defme rhe prioni ota surion or

    m dounr ol tirc divid6d ioto slots.6e d chooses a random nmber oi stors. The nleber ol slots in the window cheges according to uEexponentiat back off strateg,_r ThB mces that it is set ro one slot tne fiist rimeach time the statioa cdnot detect d idle chonel. The contentior window is rl1at the starion aeeds toafter each time slot.r In CSMA/CA, if the station finds ttre checi busy, it does nor restar.the tiher oI rie contention windowj it Etops the time. dd iestdts iwhen the .hannet becomes idle.. With all these precaution6, rnc still may b a collision resutring i,deslroyed data,

    IIOTE

    In addition, the data ftay bc co@ptcd durine thc tru6missio..The positive aclaowledgmnt ad the time-our rimr c& hehe tr&.ee rhct rlc rrc.rver has received thF trMe.Preondtiat ba.koJJ:The strateE/ of doubline the detavanehpr rs o seneral rechnique ho;h iatcral betrreen each retrasmissid,4 eaporcatiat tactofi.

    at a time, allhough the Eedia theeselves. _tF med:a used in LAxs aenFraJv conv.y irmFs fro.

    "r,> .). , "r..& gder.lly shared by .,Ir order to demmc the diffiEulties which qay a i* tbrcugh shding, .Medium A@Bs conhot {MAc) hechenis& o plotocol is DeeessaryA VAC prcLocol Eerely regdares how srarions tu.y a.cess Lh,Eediuh lD an ode.ly fashio. fo corect operation and ats.attehpts to easrue ttrat each 6tation obtains a fair sha.e of ii.

    PreFred by S,klaivey AP/ITR.cajoditu Apm

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    MAILAM ENOINEERING COLLEGEDEPARTMENT OF INFORMATION TECHNOLOGYCS23O2 Cotlptter Netuarks / IT

    LAN networks u;uaily have ordy a sinSte mcdile over which aume$ages, lepresnted o r a sdies of frmes, de talsmitted.If Lhe medium is not being used tEo, or more, stario.s haysirulrturcusly anernpt d a.ess, teading o e coltjcior.An MAC technique is thereforc requned to legulate access by statiolsto the mcdiM dd hddle the ejtect of ter, or more, stationssihultaneously attempring to access the medium.There is a.lso the ddger that once a pair of starions hasestablished comuicauon, aI othd stations may be *cluded,perhaF ind.6nitely, or at lcast for a considerabte period of tihe.A LAN does aot ueualy have dy sepdatc ntwork conrrol tunctiorNo, is a scpdat coitrol function required ro detect abnormalner work .onditions, or to conftdl r.cov.ry there from.Raiher, ch station is gmerally equaly respoosible in a I{C}t, in whichcase conriol is sid to be frllly distributed.

    'Ur$. tcncrd MAC t chniqu.s .xtst for te wttlh niUy itistlibutedHert thre is no rAulating Dechdism di6dy to govem starionsattcmptirg to @6s a mcdih. Ratn6, t@ or more stations mycortend for the medih md dy muttiple simult neous accesses deresolved as rney aise,A slnge tokeD eiists within the netftrk and is FE$e.t beeeen stationsin tura. Orny a stati@ hotding the toke @y use the medium iortmsmissio . this eliEiEtes mrntipte sibrrtaneous aeesses of th.medih witb tlte attchdmt risk of collisi@.

    Slotted lnd Egktd inertld rrng.:Similtu ia principle to token passir, bur a Eique time inteftdl isgianted to a station for tMsmission erier.

    tep@d bv S.Kalaivdy AlmR.cajDdim APn

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    MAILAM ENGINEERINO COLLEGEDEPARTMENT OF INFOIIMATION'IECENOI'GYCS%A2 Cor pute. Nen o*s /

    3. Expl.iE canter s.nse Muttiple Acces snh CoUi3to Avot talce(csMA/ca) i der.u R.ftr O.No:24. E

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    MAILAM ENGINDERING COII,EGEDEPARTMEM OFTNFORMATION IECHNOLOGYCS23O2 Caa\tuid Nehratks / ItHosts coDEcct to a Eth.met segment by tapphg inio it; tapsnust te

    A lros.ei@r - a smal1 device dnectly attached to the tap det ctswhen tlt line is idle md &ives the sigaa.l wheh rhe host istldsmittin8.It also receives incohing 3ignais.The trosceirer ir, in trm, @nnccted to e Ethemer adaptor, which isplugged into the host.Mlltiple Etheret.eAme.ts cd e joined togcr.her by repeaters.A rpearer is a ddi@ that fo dds digital sign.ls, much like an@pli6er roruads ualog sieDa_ls.Hoftver, no more tlld Iour repaters oay be positioned between aypair of hosts, Ecding tlat a Ethemet has a total rach of onty2,500 m.Ratlrer thd using a so-ohh coa ble, m Ethemer cm beconstlucted from a thiq.r cable knom G lOBaseZ; the oriSinalcable is called 1OBa6e5 (the t{,o cabtes de commonly called thln-netand thick-net, resp.ctiveM.Tn,r "10'in 10Base2 mees that tne nerwork o rates at 10 Mbps,"Base' refers to the fact that the cable is used in a basebmd system,md the '2" acds that a given segEent can be no tonsei thd 2OO m.. Today, a tlIild cable technotog, is predohinmtly used, caledI oBaseT, where ttE .T' stards tor iwisted pan.. A r oBasT sgment is usualb, limited to tess thm 1OO m in lengrh,Data tleshittcd by aly one hosr on the Ethemet .ea.hes aI rncThis is ihe good nss,Th. bad nws is that al1 rhese hosts m compering Ior access to thesde link, did ai a coDscqueDce, thy de ssjd to be in the sme

    rlo&.d tv S.Kalaimv APm' Loajadir; Arm -12

    http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/
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    MAII-AM ENGINEERING COLLEGEDEPAR}TMENT OF INFORMA'TION AECHNOLOGYCS23O2 Computet Nehhths / t

    that .ontels access to th6 shaed Ei}lmet tink.i6 comDly @Ied the Ethehet's mdia access controrqrPr.aly Eplnenled ir haidwse on th nerworrMAC). rt is

    Fr@e Fomat:;J".r d.""..e,." or Lhe llue fierds fouom and is shoq in rnF brlo.

    Preeble is 7 bJres ad @nsists of e pancm of altemating Os drl1s. This neu is used to plovid. bit synchroriatio... stan of F.ee coasi6ts of a 1o1o1or1 patteE and iDdicates thrstat of tlr frane to the reei .Destination ad.lress specifies thc destinatiotr MAC aaldtess.Sourc. addrcss specfies the source MAC adatrcs6.Lngth/1pe specmes the tue sik, i b,tes. The n,jru,lEtheme flme size is 1,51A blrs.LLC dau's dara &oE rhe LLC layer.Pad is uscd to in@4e the Eee leDgth to thc vstue eqqi.ed forcoUision detection to wrk,Frme che& sequence is 32-bit CRC for eror checking,

    o-t500i-6 2-6

    Prepded by S.Katailey AlmR.Gajendne Arm

    16

    E6.fu IEIE 302.3 LAN fu

    E :Et1Io I,d

    -t3-

    http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/http://www.civilsoftwares.com/
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    MAIL"AM ENGINEERING COI,LEGEDEPARTMENT OF INFORMAT1ON'TECI{NO[r)(}YCS23O2 Cornputer Net@rts / tl

    Addlels. Each host on d Ethemet - has a uique Ethemet address,. Etnemet addresses de t}?ica.Uy printed in a fom humans can read

    as r se+rcnce of six numbsrs sepdared y @lons.. E6.h numb.i coftsponcls to 1 byte of the 6-by e address and is givenby a pan of hsdecimal digits, one foi each of the 4 bir ni6bles in thebytej ieading 0s .E drcpped.. For e)lmple, a:0:2b:e4:b1:2 is the hMd readable represenration otEthemet addrcas as folow00001000 00000000 00101011 1t1oo1oo lol1ooot oooooot or Each Irde tldsmitted on d Ettemet is rceived by dery adaplorconrccted to rhat Ethemet.. Each adapto recogniEs ttros. frames addEssed to irs address ddpasses only those frdes on to dre host,

    /\n ftneinet adaptor rc@ives aI fr@* ed accopts. Frmes adake$ed to its ()M addressr Frmes adaL.ssed to th. brcadcast addrcss' Fimes addEssed to a multist address. iI it has be.n lnsr .redto lkten to that addfss. A11 frde , ifit hs beh p]aced in prcmiscuous dode.I' pas6es b thc host only t}le frms tiat ir accepts.I rdsdissior allonthn:

    . lh. l-F.sistant method is sihple and stlaighdoRdd.. In this method, after the 3tatior fods the tiDe idle, it sends its fra-eimdediarely (witb prcbabiriv 1).; This method h;s lhe hjchest chm@ of colision because two or morestations may fhd the line idl dd send their &@es imme.tiarely.

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    . The p- rsistent method is ued iI the .hdnel has time slots wirh ,slot duration cquel ro or greater thAn the ]Aimum Fopaaanon tim. The p-pelsistent approach combines the advetlAes of thc oL\d tst It reduces rhe chale of coUisiotr ed iEpioEs trEiency.h this method, alier the station tuds rhc line idle it fouom the* steps:. With probabitiry p, thi sration sends its f @e.r Wi$ probab-iiy q-I-p, rhe sErion wair6 fo; rhc begirin ot rhe nqrtime slot dd checks the line aAain,

    MAII,AM DNOINEERING COLLEGEDEPARTMENT OF I\FORMATION TECHNOLbGYCS%a2 conwutq Netuo/b / rt

    . Ilthe line isidle, Lr goes to step t.. Il the line is busy, it acts as though a coflision ha.occurcd dd uses the backo{ ptucedue.6. ExDLi IEEIE ao2.1l wtr.Ls t lN stuit ,ats b riet I.IEEE 802.1r (Wirelsi r-AN or wt fi)IEEE h"s d-ined &e sp.c$^a ion ,or thc wircless rA @_lcd IEE[_wn1.h covers the physical ed Data Link trFrsArchitecteIEEE a02.11 standEd defiles 2 kinds of seaices.l. The bssic seEie ser rBssr2. Trre extended sffiice;et {6ss)-r, &5ic serr . .ser I,BSSrrA Bss 's made or sEliona,y tin@bdel or @obue wileless saEo,,s drlos$brr cFntral bse sulion knom 6s *rc acccss point Ap.

    ftepad by S.Kataivoy AImR.Gajdditu Alm - t5,

    ao2 lr

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    MAILAM ENG]NEERING COLLEGEDEPARTMENT OF INFORMAT]ON TECHNOI,OCYCamputer Neruorks / i

    i lesh ar ad hoc netuorkI he BSS witlout mI rher BSS. Itis.rlle.l is stdd alone network and .Ennot send data t.

    jrl E*terded Se.dce 56r [ESSrjAn ESS is made up of Bro or nore BSS with AP. The BSS ee connectedthroueh a distlibution system, which is usually a wired -AN.An ESS uses two BTes oI stations mobil ad stationary. The mobjle: htions are nomal statioos inside a BSS. Thc stationatr starions ee Ap"rbons l-a de pd ot lhF wired LAN wheh BSS d;.o-re,Fd r."r ctwork is called d i,fcstecture netivork, In this tne stations within|ach ol one mother can cohmunicate without the use of an Ap. Bur, )mmunr.ation between two stations in two dillerent BSS usua|v occurs via

    ]'hree qu.litatively diEermt levels of hobility in a wiretess LAN.1. No trdsmission2. BSS t.msition3. ESS transirion

    I tepared b] s.Kalaivany APITR.Gajendnu AP, T l6

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    MATI-AM ENOINEDRING COLLEGEDDPAMMENTOF INFORMIflON TECHNOLiJGYcs%42 Conp)td tv.fiuorts /

    odeme.t Ircm one BSS to eothid BSS qithin rh,

    The tE' lFvel is no mobiliw. such 6s when a Meiver musr be i, r fsero.atron ro re eive " direcrionsl rrasmssion fom Lhe b* srarion or:sinele BSS.It is deincd as a 6tationsme ESS [Aluetooth).

    It is delined as a stationanother ESS. The t i d.eU phones ed Wi.Fi,IEEE aO2.1l lage,IEEE a02.1 I delin.s Lhe speci{ieuon for dr convelsion of birs ro a signat inthe physrcsl layer.The IEEE 802.11 ohysrcat tayer is oI tour rFes.t tiqu.&y.hoEptEg .prcrd sp.c&uE lFHss): k is a oplhod ,,whrh Lh Eendcr hends onr -aricr freq;ary tor a shorr mounr .Uer camer tlequency for thor he, hops aAain to sril &orher eE. do6( of tibe ad so on,

    This tdblique mak6 u* of 79 chafuels, FHSS ope.ates in the 2.4cEz ISM bdd ed apFuts data rates of I Mb/s to 2 Mb/s.t ll9: -9',iqq:1,h. orisinsr sisnar is B. rhe arocarr.r spFa.sPecrrum bmdwidrh is Nx B2. The dout of time Bpent at etub sub bdd is caled rhe dwet

    movehelt frcm a BSS in one ESS to a BSS with illevel is oobility bcisen ba6es, as is tlle case witl

    2. Dtrcct.s.quonco splq.t .pcct@ {DSSSI: lt uses sflerran suppdrinS da@ rqres oI r Mo/s ro 2 Mb/s Thelrequency rese is 2.4 GHztSM h:n.t11,P:1:.:.:n.u,_p ,j,".:mdfr is a repraced by tlE scqudce of bir.careo clup.@de. To avoid bufsing, the rrtu ;edcd Lo ;nd one chilcodr hust be Lhe s.m as ttle rimc needed o snd onc original bn.

    ?reparcd by S,Kalaivey AImR.O.jendne Ap[,I

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    IEEEIEEE

    MAILqM ENGINEERING COLLECEDEPARTMENT OF INFORMATION TECI,INOLOGYC52302 canp tet Netuorks / ffIEEE- 802.11a: Odhogolal Gcqu.Ecy iud 6n nulttplexilg(OFDM): IEEE 8o2.tta uses OFDM, ;Lich uss 12 or+ogoraj

    channels in t})c 5 GHz @ge. AI rhe sub brds de uled bv onesLree afu g'\m tihe. The.ormon d6ra rares &e ta Mbos a;d s4IEEE 8O2.lIh EtAh R.ato Dtrcctlquence spread 3pectruDtHRDssa):,EEE 802.1 rb oprates,n ue i.4 GHz b;d and _suppo,rsdarr rares ol5.s Vb/s b I1 Mb/s. rr is sidntr b DSSS excepr ior *eea. odms method whi.5 is caxed (omDlemenlary .ode ke\i;B lcc\,..C , -ncodes fou or "ishr bits ro one CCK smb;.IEEE ao2.rlg: IOrDM): IEEE aO2.l]8 ope-aE6 ar 2.i cp- edsupports even higher data rates.eo2,1l MAC rale.802.11 Fovides s*6al key fucrionaritiesr reliable data deiivery,access @ntrol, dd sccui$ featwes.

    l he MAC layer .onsists of tu sub layeis:I. The dishibuted-coordination funcrion ElSodthm (DCF) and2. The poinrcooldinatio. function algorithm (pCF).t) Polat coof.rinaaTon,t nctton lpcn Nsomrn

    the point-cooldimtioD tuf,ction (PcF) provide6 a @ntention-free sefrice.t'CF is a optiorEl leatue in IEEE 802,11 md is built on top of the DCFhrr to prcvide centlaliEd media access.2) Dt trth&e., c.odrlndtloa Ft rtctton (Dcn Atgottth^t he -D,CF akoritim uses contentior resotution, dd its sublayer impteoentsI ne CSMA s.he6e for media accss conbol dd contention res6hrri.;Itegin DCF Algorithm lor Wireless 802. i I MAC1. Th. sader seDses tlE medim for oy ongoine tlamc.

    2. If dre mediw is idtc, the s@der waits Ior a tiEe inrerEl equal ro IFS.Then rhe sddd senses dre medih aain. tf the hedrum is sri :dte,the sendd trtrsirs thF tr@e im.di.@ly,t. Afff,r the sration is foad ideal rhe sElion wails fo e p.riod oItime, .allod the distibutcd inter-iane space (DrFs).

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    MAILAM ENGINEERINq iOLLEGEDEPARTMENT OF INFORMATION TECITNOLOCYC52302 C.ttprtet Nettatka / t" 9..,1? :" snds a @orrcr f.*. ";-il-d;.;;.;.l#.;-":"iRTS) Aitq reeiving the RTS dd w"itin a .rro.t period calted th,shod i er-LMe spae rsrFsr. rr d.sE;:' i;;:;;;;;;;": .;,,.frmo cel1q6 ct.* ro send {C,rS,. ," -. ""*." "..i.". tr,,."".,Loe rdrares rhat th. desrinsrior stalion is reaoy o reeeive dek.tho or more stalions @de ry Lo send RIS tr@es ar rhe s@e 16h*e @ntrol I,e6 aay collide, The sender ssumes rhetr s beera.(oxrsDn rt rt t-as noL reLeived CIS Gde fi,om rhe receivcr dd I

    4. The solr.e slation sdds dab aJEr waidnq u @our ot Me rquaro sIFsThr^delrn"iior sEuon dkr w&Lir g tor d dobr ot ude:l:":"::1," -o .

    .rhowredsenen I to snos $"r thF f .ee

    aJicrd by thrs tfesrrss:i;n6. When a station s6ds an RTStime that it needs ro occupy l.me, it includes the dmdDd of rhlthe cllamel. Thc stations thar ar,create a tiE6 cIed a Netmrkshows how Euch time tuust Das.to check the chmel for i.lleness:Allocation Vector [NAV) rhat aIbelore rhese sralions dc 6ttoee.t

    Colli3io Avoidasce:. A wiEless protocol would fotiow the sam. slsorithm as the Erhemetwait util tl1e lint becomes idle before tresir.iDs ed backshotrld a collisjon oc.ur - ald to a first approxi@tioD, tlis is whalConsider the situationboth withiD tuge of BSuppose both A dd C

    depict;d in thc betow Egure, whre A an.l C aiwet o coIm\uicate with B dd so thev es.l

    PElaEdby S.Kataivey Ap TR.Oojendn& Alm

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    M4II-AM ENGINEERING COLLEGEDEPARTMENT OF INFORMATION TECHNOLOGYCS23O2 Cotuputer Netua.ks / ItA :ud C 4 unawde of ea.h other since their signals do not cdry

    Th( se lwo frdrDes collide with each othe. at B, butneiLher A no C is awde ofthis ..llisinnA and C se said to be hldd.n &dG. wjth .espect

    A related prcbleh, c.iled the qpo6ed lode p.oblem, occurs underlhe citumstaces illustrated in t}le below figurc, where ea.h oi tnefour nodes is able to sad dd receive sieMrs that rcach just thenode6 to its ibEedtatc lefr Md right.For exmple, B cm exchoge frm* with A dd C but it czdot .eachD, ivbne C cd reach B md D but not A.

    l'repded by S,KalaiYay A?mR.cnjadiritr AP/Ir

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    MAIIAM ENGINEERINO COLLEGE ..DEPARTMENTOFINFORMATION TECHNOLOGYnnAC FEDG CS23o2 CotuttutqNetuotks /The three ftue Eles in IEEE 802.11 defrmes, ed hmagemet frrnEs,The fr@e format for the ao2,1t MAC is shom ir

    cortlol frMes, data-ca"ryinsthe bel@ disaram ed F

    r The rrahe confol (Fc) 6eld provids infotuation on th. q?e .lrame: controt frde, data tr.ec, or maDagement Ir@e.. Duratior/connection iD (D/r) refeB to .tne time arotted tor $(successful Eemission of the f.ee.. The addressca freld denotes the 6-h5,te solre ed .lestinarioraddress fields.. The sequenc control (SC) field consists of 4 bits reseNe.l rorfgmentation dd reassehbly dd 12 bits fo a sequeace numberof fldes berween a particL d tldsoitter md recciver,' Th" I'ame bodv tield conuins a MAC sewice daE unir o. conrr.

    ' The cyclic redunddcy check (cRc) tield is Ned for eror detectioDEEE AO2.71 MACJ@

    12 6 6 6 ' ii 1

    Conuo. fiees ensu,e relidbte data delivery. The @ntrct .reesror accFsshg rhe chenet ud *knoqledAema fraffs. h.onsFr

    l 2 FCSR'ISto honitor od nanage802.1r L{N through access-2t -

    Managemen frmes areamong vdious users in thelrepdd by S.Kalaivmy ApIrR.Oajendn& Ap I

    ]EEECTS or AC(

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    MAII.AM ENGTNEERING COLLEOEDEPARIMEM OF TNFORMATION TECIiNOIr)'}Y

    ?.Eirprai h &t ll.elout toLG rtng ed it3Tor.lEr{ Rtl{os lao2.s,

    tgo ,aEL PEATU&ES OF &lltc rEalroRrA rj,g aetwork shes twir key features with d Etnemet:

    node is alowed to tmsmit.. second, aI nods Bpicsllyidentitred in the ftEm6 headeroftle fmac a3 it flows pa6t.

    Ring netsorks, like Ethemets, de 6h.Jed-media networks.IBM'S Token Ring has a nedty iderrica.l IEEE sradd.t, knom as4o2.5,402.5 dd thc later Fiber Distlibuted Data Interface (FDDI) roken ringft Do longd in widesprcad (6Imon) use.

    A ring network @n6ists oI a ser oI noiles conn.cted in a ring.Data al@ys flo&s in a p;niculd .tirection euncl thc ring, wjth ea.hnode receiviag frmes from irs up6bem neighbor ad thenlonvdding them to its doMstred neiehbor_This rirg-baed topolo$r is in coDrr6t to the Ethetuet,s bus topolos/.Lik{: the Etfumet, howwer, the ring is vired as a single share.lmedi@; it .loes not behave (act) as a @lletion of i.dependenr poih -

    c52302 c.n@ter Netwrks / tft@e l6r.t. lrovlDec2ot 1

    see a.ll frmes. with the nodeas the destination saving a copyvay ac.ess to rhe shared ring is

    rea]1yjust a specia.l sequen e oI bit6,4ode rceives @d then forards th.

    . Fi.st, it involvs a disrributed alsoiithm that controls when each

    . The wold "tokd" comes from $ecircu.lates tuoEd

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    MAILAM ENG]NEERING COLLEGEDEPARTMENT OF INFORMATION TECHNOLOGYCS23O2 Cnnprter fretua4s I n-When a node that has a trme to rtusmit sees the token, it tales $rtoken ofi the ring (i.e., ir does not toMd.l tne spcia1 bit patte.nl tutrrinstead inserts its fl@e into the ring_

    Each node along the way simply toNdds rhe trme. \uiih ttldestination node saving a copy dd foMardtng the message onro tllnext node on the rins.when the frme tuales its way back dound to rhe sender, rhis no.l,strips its rrame o$ ths nng (mther thm continuins to foryad it) mcreinserts the token.In this way, some Dode doMstled wjlt have de opporruniqr rThe tuedia access algorithm is tair in the se.se tlat as rhe tokelcirculates aound the ing; each oode gets a chance ro ransmrrNods are seniced in a round-robitr rashion.Rina topolo$, is that &y iink or .ode tailre woul.t ren.ler rhe whol('lhe problem of node failure may be a.ldlessed by connecting eaclstation into tne ring using m electlomechdicat relay.As long as the station is hea.lthy, tne retay is open a .t the statioE j:Il the station stops providjng powei, the relay closes and rhe rin:automati.aliy bypasses the station.

    Relav used on a roken ring (a) rctay open - host acrive; (b) relay ctosed hosbypassedPr.pded by S.Kalaimy AI/IIR.Cajendnh A"/IT

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    MAII-AM ENGINEERINC COI,I,E(,]F]DEPARTMENT OF ]NFORMATION TECHNOI'GYCS%42 Carqtutq Netua*s / tf

    Multisrarion active uitsSe,ere.l of thes relays de usuallv packed into a sinsle box, known asa muhstation accass uit (MSAU).. It also mal

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    MAILAM ENGINEERING COLLbGii "EPARTMENT OF INFORMATJON iECHNOLOGYCS2s02 Coavtte/ Net2atks /

    sbLioD A crpr@ rh. br.n on .t

    Sraliun D copici rhe frame and sendsrhe dau back ro th..inA.

    ligule c?riorttu Resedatlb4:

    Prepded by S.Kalaivmy AIATR,Oaiodire Apm

    That issue is addressed by the aO2.S l'fhe token contains a 3-bit priority fietpliorlry n ar ey tim_

    ocol'6 support lor difi.re.

    . Each deqce tlat wers ro send a pa(pEcket, do rhe ddj.e ce only sei* I rokeD to E4smr aif the packet's prio.iry is at least as grat as the token,s.. The pnority of rhe token cha es over timc .tue to the us of ttrelreservation bits in the frme header.. The sender ce inselt tte token b&k onto the ring imrne.iiate|fouowing it6 fraee (this is caxed edty releas) or aJrer the f.a$e irtleshits has gone al1 tte ray doud rh6 ring dd been removeo(this is ca]led delayed relea6e).

    Tokca is (av.lins alons th. rins.

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    MAII,\M ENGINEERINO COLIEGEDEPARTMENT OF INFORMATION TECTiNOLOGYCS23A2 canp"td Nduon6 / E'f okcn Ri^g lvdrntelcrce

    t eDared by S.Ktt irEy AlmRcljddimArm

    Each 402.5 token rifl8 has o* stadon desig@ted a6 a monitor.rhe monitor'sjob b to ensle the health of the ring.Any station on the ring co becobe the flodtor, ad tnere de delBedprccedws by which thc monitor is leded when the ring is fi.sto.necEd oron.h failE orLhe cu(ent monrcrA he.ltlly ronitor periodically onoEces its presence with a specialconbol hessage; if a station fails to see su.h a hessage for someperiod of time, it will asffie tiat the donitor has t6.iled dd will t.yto become the @nitor.A token may vanish fo sweral rcasons, such a a bit error, or a crashon the part of a station that was holding it. ao detct a missing token,the moLitor watches fo. a passing tolrcn mil Mintains a tim6 cqualto the rrHimun possible tol@ rctado tifl.. Ahis inteFsl equ.lsr N@Stations X THT + RinglathcyWhde N@Statils is thc lumber of stations on the ring, andRinglten@ is the lol:l Fopagalion delay ot thr rirlg.If 'he timer expires without the monitor seeing a token, it c.eates aThe monitor a&o checks Iq.o@pted or ot hoed Ames.

    -26 -

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    MAILCM ENG]NEERING COLLEGEDEPAR'IMENT OF INFORMATION TECHNOLOCYCS23A2 Coaqurer Ne. uorts / tFr@e FotEat:

    Ddtd/Com@nil Fratu:)Start deriEite (sD): The first lLeld SD is one byte e.l is use.l t.lert Lrre re.eivlng station to tbe dival of a frame as q.eu as Iallow it to srmchronize i.s retrlerdl timins.Acces. co.trol (Ac)r oae b}te Long dd includes fou sub,ieids.

    ' The fct duce birs m Drioritv Iield. "he rourh bir is careo;Leniir dd is serro DdLak rhathe flme is a data/cobeed.' The 6iLh bit is monitor bit.r The last ttuee birs de a lesepation 6etd

    . Fr.n. coEtrol {rc)r One b}re tong ed contains two lields. Thr tust is one bit field used to indicare the type orlniomarioD contained io the pDU.' The selond-uses fie reMining se\en br6 ot Lhe blt d.,(onlains inlomauon used LV lhe roLcn ring logj( -. D.Ettutto .d&eEs. {DAt:Tm NGrcsr blr DA teld conLains LIF phvsrcat addre,s of rh.frahe s nek destin2n.n

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    . c]Rq Fou t'yt6 long md cortains a CRC-32 e@r detectionr Ead it thltcr (EDl: One bl^e long md.ontains the end or the*ndd's data 6nd conkol infomation.. Fla6e 3t tu (F6lr It cd be set y rhe receiver to indicate rhat thelltme has beea read o. by thc monitor to indicate that the lreeIus already been mud the ring.

    r includes thre fields

    MAILAM ENGINDERING COLLDGEDqPARTMEI.IT oF INFORMATION TECHNOLOGYC52302 Congter Netb*s / gIf its ultimate d.stination is eot}lq n6two.k the DA is the addresso{ t}E rcuter to ttle n*t 1,1N.

    aoEC ailtlr.. (sA):Two to six brtca long ed coataia the physical addrcss of thesending station. lf thc packet has beeD rcuted ftom aorher LAN,the SA i3 th. physical addle6s of the host recent router.D.ta: The sixth licld, data is allotred 4500 hltes ed contains rhe

    > 6D - indicatcs that a &ee is cooing.> AC indicat s tiat tlrc frde i3 a token dd inctud.s the prioriv adleseration iiclds.> ED indicates tnc coal of the fGme.

    I Abon Frure;It cdies f,o information at .ll -just stdtins ed ending aleljmiters.It csl be gdcratcd t'y either by t1rc eDdr to siop its owntEnsmi3sioi or by th. monito. to purge d old trdslssion frcm the

    Jqded by S.Kalaimy AImR_G.jenditu AP,{r

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    8, Irl..cu. tL. \Ertoui sp.ct3 of FDDI nT,IBER DISIRIBMED DIITA IIIIER}ACE

    MAII,AM ENGINEERING COLIbGE .'DEPARTMENT OF INFORMAIION TECUNOLbGYC52302 Coqtutd Netuhns / trlllct {. [oy/D..2O11

    FDDI

    Fib.r distributed dara interf@ (FDDI) is a local ea network proioc(,stedardized by ANSI ed the ITU_T.t It suppolrs data efes of 1OO Mbps dd pevi.les a high-specd.copper vc,siotr of FDDI is lo@m as CDDI.

    FDDI opeEtioDA@ M.tho* ,okan passt^gln FDDI, trccss.s limiled by riEe.flro It?Es or IRa.[ ES. Slhchonous - refcE to info@tio that k rear_time. F_n@e) AsynchrcDous - refos ro iDromatioo that is not ca.t-tine. O ri*OErch starion captws the roL.n is requircd o send S-Iree tusLAny remMmg t,me may thq be ued to stud A irlres.Tlme Regbt ts. FDDl,defn.s.rhree timc regsLer o tutrtrct cirutation ot l,he token eLd'sboure l]nk a@ess opporujrics 5e@g tE nodes equiLab.y.Tte registere qe:. :l.T,L1:::8" audayon {sA,: rr indieres the rcnsLh or rin" alok-cacn staEon lor 6ending slarchronous data. Tareer roLen rcra@n dme ITTRT): rndi@res rhe av@pe rihe Foutrecund rhc .ing ..@tly [email protected] by S.Kataivey A.pmR.Cajodi@AIm -29-

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    '1cs2302 canPutet Netua.ks / rI. Absolute lruimu time (AMT)| holds a value equar to twice &e TTRT.

    MAILAM ENGINEERING COLLEGEDEPARTMENT OF INFORMAT]ON TECHNOLOGY

    )ach station.ontains a set ol timers that enable it to compare actualr rmings u'ith the va.lues contajned in the resiste.s.\ o tirets uscl bg FDDI

    aokm rotation timer (IRT) runs continuously md Deasures the( rual dne b*en by Lhe token ro compiFlr a ry,'-Tokm holdins timer FHT) - ir begins runnins as soon as the tokenis recei@d. Its fuctior is to show hd much time remains forsending dlrchionous frmes once the slnchronous frmes hale

    tepded bv S.(alaiv@y A?mR.Gajqdiian AP T

    the diflerence between lTm alrd-TRT (THT='I"IRTTRT),o/ mT is reset to aro {mT=o)Thc station sdds it sralchronous data.rhe station sends asynchronous data as long as the value of THT is

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    MAILAM ENGTNDERING COLLi9GE ..oepaRfluembiiN'Fb-RMr i;oi-6-c-iN-or.bovC92s02 Conwtat Nen orks / L.

    FDDI laydsInglcal Llak Co,tttolThe LiC layer is siDild toM.arld A6eq Contrct

    IEEE 802 2 prcbo@ts.

    . Stalt deiimiter ISD): thc first blte oI the Iield is the f@e,s stafti.cflae.. Frde @trtrc] (Fc): the second bl4e of th. A5IDe identites the iidtAddres*s: tne D*r two felds e the.te.timtioD md sorEe addres:Data: each dara tdre cm cary u ,to 45oo byres of ctata.CRCiEnd deliniter (ED)r conststs of harf a t re in rhe .tata trde or a tulbyle in rhe token ft2fie F.me status (FS): ft is include.t in the data / otr]tlEd frme.

    P.epded by S.Kaldhy AlmR.Cajendne AP/IT

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    MAILAM ENGINEDRING COLLDGEDEPARTMEM OF INFORMATION TECHNOLOGYCS2so2 Coryatter Nettuorks / t)tnptetuentdtion: Phusiel Mediutu Depeident tpMpl a@t

    l'MD layer deEles the Equired comecriom dd elsctrc4ic components.r The data ]f,alsmbsion is cor.fined to the prioary rins,e secodary ring ie pr@ided in cffi rhe primary fai1s.

    FDDI ringcond$y ring f,u.kes FDDI seff-hearing.elPfpiobldnecYls on the primary rins,

    lr@aid bv S.Kalaimy APmRoajeqtlim AIm

    led to cohPl.te data crcuits d aintain

    \o les comect to one or boLh rings u6ine a hedia rnrerldre .onr..-ortMlC) tfsr co be othd m.l. or femle comedor

    FDDI rinS 6Jter a failue

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    MAILAM DNGINEERING COLLEGEDEPARTMENT OF INFORMATION'|ECHNOLOGYCS23O2 Conpuler Neteo*s / t,

    Thtee tUpes o tudes:r DAS - A dual attachmeEt sration b6 two MrC ed cornecred to borirings sives ir improved retiabnjt ed throughput,. Faults de brpdscd by a stationis maling a uap connection from thrpnm@ nns ro tE scondary ro silch 6iepals trcm one mpuL I.. SAS - A Single attaclme.t station has onty one Mlc ald connected t.. Robustness is achieved by co@ectile SAS8 to intemc.tiate nodescalled dual attaihrr@t concentlators (DACS)". This .onfigutation allows each station to opeEte through a siople Nr(

    with only one input dd one output, DAc - A dual attachmnt concentrato. connects d SAS to rhe dualing, It provides nrappitrg did coDtrot ftEctions.

    Preparcd by S.Kalaihy AlmR.cajndiran Ap4r 33-

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    I

    MAII.AM ENGINEERINO COLLEGEDEPAR'TMEM OF INFORMANON TECHNOLOGYC52302 Chnp ler NetDrks / rlDllcar ?ot n F&g [GiUa Ac6* coEtlol tn d6ta[. _

    Refer Q.NO:iI O. Dl*$. tnc ve.tous sp.ct of Bddg.r tit

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    MATL1.I,I ENGINEERING CoLLEGEDEPARTMENT OF INFORMA'TION TECIINOLi]CYCS23o2 Conputer Nehlotts / 1'r Do the sme for y-to,X traffrc.

    DesiAn aspecrs oi bridge alc s foltows:. The bridge mal

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    MAII-A]II ENGINEERINC COLLEGEDEPARTMENT OF INFORMATION'TECI{NOLOGYC52302 C,np Et Nehtorb / rrIt pr{oms its ()m bridgins tuoctions ed buitds it host address to

    segment nmbd nEpping table y tuining aod usi.g the sourc.md destination addrcsses insid the received fid,cs.Whm a bridge receives a flme from a host, it ffiines its table tocheck if the addr* of the sending lrcsr is ailable in the rable.If not, it adds it to the table along with its seement nmber.Thcn it looks at the destimtion addrss to see if thai is available in itsmapping tabte and, if available, delivcrs ttE frme ro that segment,tloweve., if the destinatior address, md thdefore rhe segment.uobd ol the d$tination ad&ess, is not available, the bridge sendsthe frde to all thi segments ro which it is come.ted,ln thi6 Ir)5mer, ov.. a period of tim., tnc bridge conskucrs thecomplek Eapping beareen th. hosts dd thei. seshent numbers forthe entir network.. Since lhe bridge .ortinucB checking ud updating its mapping tabLeali the time, qm if ns hosts 4. addcd, existing h@rs de removedor $eir NICB iplaced, it does not matter.'rhe bridge lees about these chdBes and adapts to them automatically.

    Ntlli@ra M.r.r.:. A multiport hridCr when a simple 6r

    segments is calcdI 1. Dilcs. tL. BriosSWITCIIES

    is a special case of either the siDple or the leminglemiDg bridge comects ho.e thm two network. r,.ct3 olSrttche h .tct.il.

    . A switch is a aombimtion oI a hub ed a blidge.r It car int r@mect twd or oore woikstations, but like a bridge, itobswei, tlanic flow and lem6.r Wbd a frame dires at a ssitch, the 6witch *mines the destinationad(liess dd forrdds the Ade our the one n@essd cotuection.

    rirepded 61 S.Kalaivey APmR.Gajddird A?m

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    M?TIAM ENGINEERING COLLbGE ..DEPARTMENT OF INFORMATION IECHNOLOGY

    r The backplde of a sitch is f*t eDough to support mlrlliple darrtresfers ar o.e timeA swirch that employs a at-thrdgh drchnedure i,i one that passes or ,lhe frme before rhe enrile frde has @ived at the switchMultiple worl3tetions connected ro a switch use dedicared segmentsThis is a very eihcient My to isolatc hea .y users nom tlE network.A switch cd allow simulraneous access to hultiple servers, olhultiple siEulteeous connections to a siasle serylr.

    ru.lo rcre of Swlt.h6.t Isolating tlajlic pattems @d providing multiple [email protected],' This design is usuatty done by the netrrork muaser.Switches ae easy to install ad have components that de hot-swappable,workstatlons copected to a dedicar.d se

    cs2302Workstations that connecr to a hub de oDWorkstations ttlat connect ro a switch

    Prcped by S,Kalaiv&y AP/ITR.cajmditu Apm -31_

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    MAILAM ENGINEERINO COLLEGEDEPARIMENT OF INFORMATION TECI'NOLOGYCS23O2 Conptuter Netbrks / EtuU D plq San@hes. A fr dupl* swirch allows for simultdeous tcnsmission and

    r eceprion ofdets ro ed trcm a workstarion.. Problem with Ethmet h.]f dupla.' This 6 dupl* coDeltiotr helps to eliminate ollisions.t To support a tull duplx @mectioh ro a sitch, two sers of wires,ft necessary - one for the receiae opehtion md one Ior the{dsmit opcration-12. Explat tl coac.pt ol ttuultt i algotithD ta ittsI: res E es adc9 i h ai

    . The l-persistent rdthod is simple md stEightforyard.. In this method, aftr the station lnds the tine idle, it sends it6 frdeiqmcdiately (with pnobabiutv 1).r This metlod has thc highest chmce oI colisiotr because rwo or morestations hay fhd thc line idle md send their frms immcdiately.

    . The p-peisistdt m.ttDd is used if the chdnl has time slots with aslor duration equal to or greaier Gd Ltc mdimur prcpagaron r're.. ah. p-pcrsktent approach combines the advdtages ol the other twostrategies.' lr'Fcluces tbe chdrce of @Uision ffd hprov.s e,1ic'-rryln this hethod, ejter tt.re station fin& the line ide it follows these stepsl

    . Wiih probability p, th stationsends its Irde.' wnh probabitty q'1 p, the starion waits for the beginning of the nexttime slot dd chccks the line asain,. If the line is ide, irCoe6 to step 1.If the line is buqr, it acts as thoush a collision hasoccuftd dd use8 the backofi procedule.

    lleparcd b,v S.Kalaivdy AlmR.O.jnilim AL{T

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    MAIT.AM ENCINEERING COTTEC;DEPARIMEIT oF INFoRI O{ToN TEcHNoLbGYCS23d2 cotit@/tet Nenulrks /

    13. Btatc rhEG gcetrl UAC t .t rCu.. dr roE rs enbrr frIfyd.ttlbEt d s.tmrtEl Refd Q.NOr214, aht. ttc tro tshiL ot sElcc. ?E rd.d ty tlAS a(xllt .trdEd.R.{6 e.NO:6rB. Et'Lln tL vrriou .rt gorra of Ertdi . tE.Lt rI

    Rerde.NO:1o