Mạng truyền tải quang WDM

THUT NG VIT TTADM Add Drop Multiplexer B ghp knh xen/rAOTN All Optical Transport Network Mng truyn ti ton quangAPD Avalance Photodiode Dit tch sng thcAPS Automatic Protection SwitchingChuyn mch bo v t ngARC Alarm Reporting Control iu khin bo cnh bo ASE Amplified Spontaneous EmissionPht x t pht c khuych iAST Alarm Status Function Chc nng trng thi cnh boATM Asynchronous Transfer Mode Ch truyn khng ng bCTP Connection Termination Point im u cui kt ni DEMUX Demultiplexer B tch knhDLE Dynamic Lightpath EstablishmentThit lp tuyn quang ngDLP Dedecated Line Protection Bo v on ringDPP Dedecated Path Protection Bo v tuyn ringDP-WSHR Dedecated-Path-Switched WDM self-healing ringRing WDM t hi phc chuyn mch bo v tuyn ringEDFA Erbium Doped Fiber Amplifier B khuych i si c pha tp ErbiumFWM Four-Wave Mixing Trn bn bc sngHP Higher order Path Tuyn bc caoIP Internet Protocol Giao thc Internet ITU International Telecommunications Union Lin minh vin thng quc tLCLink Connection Kt ni tuynLOS Loss Of Signal Mt tn hiuLP Lower order Path Tuyn bc thpLSA Link State Advertisement Thng bo trng thi tuynMPLS MultiProtocol Label Switching Chuyn mch nhn a giao thcMPS MultiProtocol Labda Switching Chuyn mch bc sng a giao thcMS Multiplex Section on ghp knhM-WSHR Multiple WDM Self Healing Ring ProtectionBo v a ring WDM t hi phcMUX Multiplexer B ghp knhNZ-DSF Non-ZeroDispersion Shifted FibreSi dch tn sc khc khngiOA Optical Amplier B khuch i quangOADM Optical Add/Drop Multiplexer B ghp knh xen/r quangOBPSR Optical Bi-directional Protection Switching RingRing chuyn mch bo v tuyn hai hng OBS Optical Bust Switching Chuyn mch cm quangOC Optical Carrier Truyn ti quangOC-DPRing Optical Carrier-Dedicated Protection RingRing bo v dnh ring truyn ti quangOCG Optical Channel Group Nhm knh quangOCh Optical Channel Knh quangOCh-DPRingOptical Channel-Dedicated Protection RingRing bo v dnh ring knh quangOCh-SPRingOptical Channel Shared Protection RingRing bo v chia s knh quangO-E-O Optical-Enectronical-OpticalBin i quang-in-quangOMS Optical Multiplex Section on ghp knh quangOMS-DPRingOptical Multiplex Section -Dedicated Protection Ring Ring bo v dnh ring on ghp knh quangOMSP Optical Multiplex Section ProtectionBo v on ghp knhOMS-SPRingOptical Multiplex Section SharedProtection Ring Ring bo v dng chung on ghp knh quangOS Optical Source Ngun quangOSNCP Optical Subnet Connection ProtectionBo v kt ni mng con quangOTDM Optical Time Division MultiplexingGhp knh quang phn chia theo thi gian OTM Optical Termination MultiplexerB u cui ghp knh quangOTS Optical Transmission Section on truyn dn quangOXC Optical Crossconnect Ni cho quangPCM Pulse Code Modulation iu ch xung mPDH Plesiochronous Digital HierachyPhn cp s cn ng bPIN Positive Intrinsic Negative Cu trc bn dn P-N c lp t dn bn trongPPS Path Protection Switching Chuyn mch bo v tuynQoS Quality of Service Cht lng dch vSDH Synchronous Digital Hierachy Phn cp s ng bSNCP SubNet Connection Protection Bo v kt ni mng conSNR Signal-Noise Ratio T s tn hiu trn nhiuSONET Synchronous Optical Network Mng quang ng biiTDMTime Division Multiplexing Ghp knh phn chia theo thi gianTWP Tuneable Wavelength Path Tuyn bc sng ng hmVC Virtual Carrier Mch oVRA Virtual Ring Architecture Kin trc Ring oVWP Virtual Wavelength Path Tuyn bc sng oWC Wavelength Converter B chuyn i bc sngWDM Wavelength Division MultiplexingGhp knh phn chia theo bc sngWP Wavelength Path Tuyn bc sngWR Wavelength Receiver B nhn bc sngiiiLI NI UX hi pht trin ko theo nhiu ngnh khc pht trin mnh m, trong c vin thng v cng ngh thng tin nhm p ng nhng nhu cu ngy cng nhiu v cng cao ca con ngi. Khch hng ngy cng c cung cp nhiu dch v mi vi cht lng v tc c ci tin. iu ng ngha vi vic cc nh cung cp phi ci thin cc cng ngh c v nghin cu cc cng ngh mi m bo cung cp cho khch hng cc dch v: m bo cht lng m gi thnh thp. Mt trong cc gii php c a ra l cng ngh ghp knh theobcsng(cngnghghpknhquangWDM). Khi nimghpknh quangxut hintnm1958, nhngmi nnm1997Tomlinsonv Aumiller mi a vo ng dng u tin trong thc t. Ghp bc sng quang hay cn gi l ghp knh quang theo tn s l mt phng thc truyn dn mang li nhiu li ch v kinh t v vn qun l mng. Chnh v vy m phm vi ng dng ca n m rng mt cch nhanh chng. Cc nh t chc th vn hi Olympic ma ng 1992 s dng tuyn cp quang ghp bc sng truynccchngtrnhgiaccaimthi unthnhphAlberville. Hin ghp bc sng quang c ng dng rng ri trn cc mng truyn dn nh h thng truyn hnh cp, trong mng ni ht, trong mng truy nhp thu bao v ch yu l trong cc h thng cp quang bin. Vit Nam, mng li truyn ti quang trong nhng nm qua p ng c nhu cu ca ngi s dng. Nhng vi xu hng pht trin cc dch v a phng tin (yu cu bng thng ln) th mng truyn ti s sm ri vo tnh trngquti. Chnhv vy, cngnghghpbcsngquang(WDM) c chn lm gii php gii quyt vn . Thng 4 nm 1998, Vit Nam bt u trin khai xy dng trm cp b tuyn cp quang bin SEA ME WE 3 ni 33 quc gia khc nhau ca Chu v Ty u c tc bit vo cui nm 1999 ln ti 40 Gbit/s. y l tuyn thng tin quang ng dng cng ngh ghp bc sng quang u tin ti Vit Nam.Bng tn truyn dn ca si n mode rt rng. V vy gii php ghp knh theo bc (WDM) sng s lm tng dung lng v gi thnh li thp. Hn na ivghp knh theo bc sng cn c p dng trong nh tuyn v chuyn mch quang. trin khai mt h thng truyn dn WDM cn phi gii quyt rt nhiu cc vn t ra nh l nh cu hnh mng, thit k tuyn, bo v mng, nh tuyn v phn b bc sng duy tr hot ng an ton mng th mt trong nhng vn t ra l cn phi nghin cu vn bo v v phc hi cho mng. V vy trong n ny em s tm hiu nhng gii php bo v, phc hi ph hp cho mng truyn ti quang WDM. t c mc tiu trong n ca em i vo tm hiu nhng vn chnh:Tng quan v cng ngh WDMBo v trong mng truyn ti quang WDMPhc hi mng v phn b li ti nguyn Mc d ht sc c gng, nhng chc hn cc vn nu ra trong phm vi n ny cha th hon chnh v mt vn ht sc quan trng nh vy. Ni dung ca n vn cn c cc vn cn phi xem xt thm v khng th trnh khi nhng khim khuyt. Rt mong c cc Thy C gio ch bo, cc bn sinh vin v cc bn c quan tm ti vn ny gp , ch dn thm.Em xin c cm n su sc Thy gio TS. Bi Trung Hiu, ngui Thy ht sc to iu kin gip , hng dn, ch bo, gip em hon thnh n ny.Em cng xin cm n cc thy, c gio trong B mn Thng tin quang - Khoa Vin Thng 1 ch bo dy d truyn cho em kin thc. H Ni, ngythngnm 2005Sinh Vin Nguyn Trng Cng [dB] [m]1,5 1,6vCHNG I TNG QUAN V CNG NGH WDM1.1.Gii thiuNhng nm gn y, cc dch v thng tin tng trng ngy cng nhanh chng, yu cu v dung lng truyn dn ngy cng ln, ng thi yu cu v cht lng truyn dn cng ngy cng kht khe hn. thch ng vi s tng trng khng ngng v tho mn yu cu tnh linh hot ca mng, cc cng ngh truyn dn khc nhau c nghin cu, trin khai th nghim v a vo ng dng, trong s phi k n cng ngh TDM, WDM, OTDM, Soliton.Vi cng ngh TDM, dung lng h thng c th t ti 5 Gbps, tuy nhin y cng l gii hn dung lng ca cng ngh ny. Vi nhng g khng t c ca h thng TDM v mt dung lng th h thng thng tin quang da trn cng ngh WDM li p ng c.Cng ngh ghp knh theo bc sng quang (WDM -Wavelength Division Multiplexing) l cng ngh truyn ng thi nhiu bc sng khc nhau trn mt si quang, vi dung lng trn mi bc sng quang in hnh l 2,5 Gbps. S lng ghp thng l (2 16) bc sng (trong tung lai, con s ny cn ln hn). u vo, cc bc sng quang mang thng tin (cc knh quang) c ghp trn cng mt si quang vc truyn dn ti u thu. Ti u thu, cc bc sng ghp c tch ra bng cc b tch knh quang. Dc theo tuyn truyn dn c th c cc b khuch i quang b li suy hao truyn dn. Cng ngh ny thc s cho hiu qu truyn dn rt cao m khng qu phc tp. Di y l mt tnh ton cho thy s hp dn ca cng ngh WDMBng tn truyn dn ca si quang l rt ln; Ch vi ring ca s quang 1550 nm th di bc sng c th s dng l 1500 nm 1600 nm, tng ng vi di tn rng c 12,5 THz. [dB] [m]1,5 1,6viS dng cho tc truyn tin c 10 Gbps th ch cn s dng mt phn rt nh trong bng tn truyn dn ny. R rng, c th thy dung lng yucu c hng trm Gbps l hon ton nm trong kh nng ca h thng WDM. Thm vo , h thng cn rt mm do khi c cc phn t nh b tch ghp quang, b ni cho quang, chuyn mch quang, cc b lc quang thc hin la chn knh ng hoc tnhCc cng ngh khc nh OTDM,truyn dn Soliton th dung lng c p ng rt tt nhng li qu phc tp, bi th m gi thnh h thng li tr thnh vn ng quan tm.Cng ngh WDM vi s nng cp m rng dung lng pht trin dch v bng rng, khai thc y tim nng bng rng ca si quang, thc hin truyn dn thng tin siu tc, c ngha rt quan trng trong truyn dn cp si quang ni ring,trong cng nghip vin thng ni chung.Thc s, n l cng ngh ng c quan tm, nghin cuv trin khai ng dng rng ri.1.2.Tin trnh pht trin mng truyn ti thy r c xu hng pht trin mng trong tng lai, trc ht nhn li lch s pht trin ca cng ngh mng truyn ti. Cng ngh mng tri qua cc giai on chuyn i t tng t sang s, t phn cp s cn ng b(PDH) sang phncp s ng b (SDH) v gn y l t SDH sang WDM (ghp knh phn chia theo bc sng). h tr v tng thch hon ton vi cng ngh c th cng ngh chuyn mch mi phi thch hp vi cng ngh truyn dn trc. Chng hn cng ngh PCM c chuyn mch mc 64Kbit/s v truyn dn mc 2Mbit/s; khi chuyn ln PDH th ni cho mc 2Mbit/s v truyn dn Pha ca mt ngun quang [dB]Bng tn ca s 1550 nmHnh 1.1 Bng tn truyn dn si quang. [m]0,70,8 0,9 1,01,11,21,3 1,41,5 1,61,5 1,6viimc 140Mbit/s; v khi ln n SDH th ni cho mc 155Mbit/s v truyn dn mc 10Mbit/s.Cn vi cng ngh WDM th cha c xc nh r nhng theo d on th tc chuyn mch c s c 300Gbit/s tng ng vi dung lng truyn dn 10Tbit/s.Da theo lch s pht trin v nhu cu hin ti th cng ngh WDM t nht cng p ng c trong mt thp k. Trong tng lai, sm hay mun th cng cn c cng ngh WDM pht trin hn v c l c kt hpvi cc kthut xltnhiuquangnhghp knhtheothi gian quang(OTDM) v chuyn mch gi quang cng vi cc trm lp quang 3R m rng trong sut ca mng. Trong tng lai xu hng tin ti mng ton quang (photonic). xy dng nn mt mng truyn ti photonic kh thi v c li v kinh t th ngoi thch thc ban u v cc cng ngh ng truyn quang cht lng cao, cc b ni cho, v cc nt chuyn mch quang th cn cn phi vt qua thch thc v cu trc mng. Yu cu quan trng nht ca mt mng truyn ti l n cn c cu trc tt. Yu cu ny cng c thc hin tng t nh ca cc mng SDH hin nay. Cc thnh phn cu trc s bn l cc topo Ring v Meshvcththptheovi cchnhkt hpRing/Mesh, phncpa Ring. Hnh 1.2 ch ra xu hng pht trin c th ca mng truyn ti photonic tng ng vi s pht trin cng ngh cc khi c bn.Khi xy dng mng th cng cn c s gim st xem ci g s xy ra trong mng. Trong khi khai thc chc chn s gp phi cc s kin c d liu trc v cc s kin khng xc nh trc v i khi khng mong mun. Do cn c h thng bo hiu v gim st cho mng. So vi mng SDH, th c rt nhiu vn cn phi c cp trong mng WDM. V d gim st t l li bt quang r rng lm d dng hn cho hot ng ca mng WDM. Cn c cc tiu chun v mo u v bo hiu pht trin cc thit b mng WDM.viiiRo cn quan trng tip theo cn vt l pht trin mt m hnh thng tin hiu qu trch v x l tt c cc trng thng tin nhn t mng. Cc th nghim ch ra rng p dng thng cch tip cn m hnh phn lp c pht trin cho mng SDH ny ra mt s vn i vi mng WDM. Khi pht trin cc h thng qun l cc mng WDM c bn cht tng t vi nhiu hiu ng vn cha c xc nh r ny ra cc thch thc mi cho nghin cu.1.3.Cng ngh WDM1.3.1 u nhc im ca cng ngh WDMSo vi h thng truyn dn n knh quang,h thng WDM cho thy nhng u im ni tri:ixRing WDM kt ni y Ring WDM kt ni tp trungOADM OADMTruyn dn WDM im-imTruyn dn WDM chui c OADMOADMOADMOADM OADMOADMOADMOADMOADM OADMOADMoxcoxcoxcoxcoxcTopo Mesh v kt ni cc RingXu hng pht trin cng ngh1996 1998 2000 2002Hnh 1.2Xu hng pht trin kin trc mngDung lng ln truyn dn lnH thng WDM c th mang nhiu knh quang, mi knh quang ng vi tc bit no (TDM). Do h thng WDM c dung lng truyn dn ln hn nhiu so vi cc h thng TDM. Hin nay h thng WDM 80 bc sng vi mi bc sng mang tn hiu TDM 2,5Gbit/s, tng dung lng h thng s l 200Gbit/s c th nghim thnh cng. Trong khi th nghim h thng TDM, tc bit mi ch t ti STM-256 (40Gbit/s). Loi b yu cu kht khe cng nh nhng kh khn gp phi vi h thng TDM n knh tc cao.Khng ging nh TDM phi tng tc s liu khi lu lng truyn dn tng, WDM ch cn mang vi tn hiu, mi tn hiu ng vi mt bc sng ring (knh quang), do tc tng knh quang thp. iu ny lm gim ng k tc ng bt li ca cc tham s truyn dn nh tn sc Do trnh c s phc tp ca cc thit b TDM tc cao. p ng linh hot vic nng cp dung lng h thng, thm ch ngay c khi h thng vn ang hot ngKthut WDMchophptngdunglngcaccmnghincm khng phi lp t thm si quang mi (hay cp quang). Bn cnh n cng m ra mt th trng mi l thu knh quang (hay bc sng quang) ngoi vic thu si hoc cp. Vic nng cp ch n gin l cm thm cc Card mi trong khi h thng vn hot ng (plug-in-play). Qun l bng tn hiu qu v ti cu hnh mm do v linh hotNh vic nh tuyn v phn b bc sng trong mng WDM nn n c kh nng qun l hiu qu bng tn truyn dn v cu hnh li dch v mng trong chu k sng ca h thng m khng cn i li cp hoc thit k li mng hin ti. Gim chi ph u t miBn cnh nhng u im trn WDM cng bc l mt s mt hn ch nm ngay bn thn cng ngh. y cng chnh l nhng thch thc cho cng ngh ny Dung lng h thng vn cn qu nh b so vi bng tn si quangxCng ngh WDM ngy nay rt hiu qu trong vic nng cao dung lng nhng n cng cha khai thc trit bng tn rng ln ca si quang.Cho d cng ngh cn pht trin nhng dung lng WDM cng s t n gi tr ti hn. Chi ph cho khai thc v bo dng tng do c nhiu h thng cng hot ng hn.1.3.2 K thut ghp knh theo bc sngGhp knh theo bc sng (WDM) l cng ngh c bn to nn mng quang. K thut ny tn dng bng tn ca si quang bng cch truyn nhiu knh bc sng quang c lp v ring r trn cng mt si quang. Mi bc sng biu th cho mt knh quang trong si, ta c th hiu l mi mt mu sc khc nhau l mt knh thng tin quang khc nhau. V nh vy tn hiu truyn trn h thng WDM s ging nh mt chic cu vng. Mc d bc sng ng dng trong thng tin l nhng bc sng khng nhn thy, song y l mt cch thc rt trc quan m t nguyn l ny. Trn mt si quang hoc mt h thng thng tin quang ta c th ghp bc sng quang theo mt hng i hoc c hai hng i v hng v. Theo thi gian,khi nim WDM c thay bng khi nim DWDM.V nguyn l khng c s khc bit no gia hai khi nim ny, DWDM ni n khong cch gn gia cc knh v ch ra mt cch nh tnh s lng knh ring r (mt knh)tronghthng. Nhng knh quangtrongh thngDWDM thng nm trong mt ca s bc sng, ch yu l 1550 nm v mi trng ng dnghthngnylmngngtrc, clytruyndndi vdunglng xiHnh 1.3 Nguyn l c bn ca h thng thng tin quang WDM...n......12... n 12... nMUXDEMUX1n2.... ....12truyn dn ln. Cng ngh hin nay cho php ch to phn t v h thng DWDM 80 knh vi khong cch knh rt nh (xp x 0,5 nm). thun tin chng ta dng thut ng WDM ch chung cho c hai khi nim WDM v DWDM.Nhn bn ngoi, mt h thng truyn dn WDM v mt h thng truyn dn quang SDH c rt nhiu im tng t. C hai h thng u c: Cc thit b ghp tch knh u cui (MUX, DEMUX). Cc thit b khuch i ng truyn hoc lp (Line Amplifier, Regenerator). Cc thit b xen/r knh (ADM). Cc thit b u cho (Cross-Connect Equipment). Si quang.Tuy nhin khc bit quan trng gia chng l ch: H thng truyn dn SDH ch dng mt bc sng quang cho mi hng pht, cn h thng WDM th dng nhiu bc sng (t hai bc sng tr ln); i tng lm vic ca h thng SDH l cc lung tn hiu s PDH/SDH, cn ca h thng WDM l cc bc sng v cc bc sng ny khng nht thit chuyn ti tn hiu s. Mi bc sng c chc nng nh mt si quang cung cp mi trng truyn tn hiu cho h thng khc v v vy gi l si quang o.WDM ra i nhm p ng nhu cu tng vt v bng thng do s pht trin cha tng thy ca mng my tnh ton cu Internet, s ra i ca cc ng dng v dch v mi trn nn tng Internet. Trc WDM, ngi ta tp trung mi n lc nng cao tc truyn dn ca cc h thng SDH nhng kt qu thu c khng mang tnh t ph v cng ngh x l tn hiu in ti tc cao dn n gii hn. Khi tc t ti hng chc Gbit/s bn thn cc mch in t khng th m bo p ng c xung tn hiu cc k hp. Thm vo chi ph cho cc gii php tr nn tn km v c cu hot ng kh phc tp, i hi cng ngh rt cao. Trong khi bng thng cc ln ca si quang mi c s dng mt phn nh. Tuy nguyn l ghp knh theo bc sng WDM rt gn vi nguynlghpknhtheotnsFDM, nhngcchthngWDMch c thng mi ho khi mt s cng ngh x l tn hiu quang tr nn chn mui, xii Kt nion khuch iKnhon khuch i Knhon khuch i on khuch iHnh 1.4 Cc lp con trong lp quang ca mng WDM

trong phi k n thnh cng trong ch to cc laser ph hp,cc b lc quang, v c bit l cc b khuch i ng truyn quang di rng (khuch i quang si EDFA, khuch i Raman).Cc laser ph hp c tc dng gim ti a nh hng ln nhau ca cc bc sng khi lan truyn trn cng mt si quang. Cc b lc quang dng tchmt bcsngrakhi ccbcsngkhc. Ccbkhuchi ng truyn di rng cn tng c ly truyn ca tn hiu quang tng gm nhiu bc sng, nu khng c cc b khuch i ny th cc im cn tng cng sut tn hiu ngi ta phi tch cc bc sng ra t tn hiu tng, sau hoc l khuch i ring r tng bc sng ri ghp chng tr li, hoc l phi thc hin cc bc chuyn i quang- in-quang trn tng bc sng ri mi ghp, v nh vyth tn km v lm cho h thng tr nn km tin cy.1.3.3 Cu trc mng WDM1.3.3.1. M hnh phn lpTrong d tho khuyn ngh G.otn ca ITU-T th mng quang s c phn chia thnh ba lp, nm di lp on lp trong m hnh SDH. Lp knh quang, cn gi l lp tuyn quang (OCh Optical Channel). Lp ny c chc nng nh tuyn t u n cui cc tuyn quang. Mi OCh i qua mt s on khuch i trong mng v mi on khuch i mang nhiu bc sng. Lp on ghp knh quang(OMS Optical Multiplex Section) c s dng m t mt chng im ni im dc tuyn quang. Mi OMS bao gm mt s on lp nm gia hai b khuch i. Lp on truyn dn quang, hay cn gi l lp khuch i quang(OTS Optical Transmission Section). iu cho ta thy mi on ghp knh quang thuc v lp khuch i quang.Electronic Layer (Lp in) W D M OCh -Lp knh quang OMS -Lp on ghp knh quang OTS - Lpon truyn dn quangxiiiHnh 1.5 V tr ca h thng WDM trong mng truyn ti

Kt nion khuch iKnhon khuch i Knhon khuch i on khuch iHnh 1.4 Cc lp con trong lp quang ca mng WDM

Trong m hnh phn lp giao thc mng truyn ti di y th quan h lp ATM; SDH vi lp WDM l quan h gia lp client v lp server. Cc tn hiuSDHvATMdidinchodchvlpclient mcmangtrnh thng WDM.Nu xt n khi nim phn lp mng th h thng WDM c xem nh phng tin vt l, cng vi si quang to thnh lp knh quang Di gc pht trin h thng th WDM cng vi thit b xen/r knh quang (OADM) v b ni cho quang (OXC) s to thnh mt lp mng quang. S pht trin ny tin ti mt mng truyn dn s dng knh bc sng hay ni ngn gn l lp mng quang di lp client, tc l s tch mng truyn dn v topo thnh hai lp quang v in trong h thng WDM l ht nhn ca lp mng quang.xivHnh 1.5 V tr ca h thng WDM trong mng truyn ti

ATM SDH MPLS Giao din quang m SDHATMMng quang hin tiB khuych i quang Kt nion khuch ion ghpKnhon khuch ion ghp Knhon khuch ion ghpon khuch iNt WDMHnh 1.4 Cc lp con trong lp quang ca mng WDM

Nt WDM Nt WDMVi s pht trin mnh ca cc thit b chuyn mch quang v chuyn i bc sng th xu hng tin ti mng ton quang l khng xa.xvLp mch in(nh ATM, IP...)Lp knh SDHLp knhquang WDMHnh 1.5 V tr ca h thng WDM trong mng truyn ti

OXC v OADMB nh tuyn v chuyn mch ATMDXC v ADMATM SDH MPLS Giao din quang m SDHATMMng quang hin ti1.3.3.2Cc phn t trong mng quang WDM Cu trc chung v cc thnh phn chnh ca h thng thng tin quang WDM c th hin trong hnh 1.7.Ni chung, hthngWDMbaogmngunquang, bghp/tchknh quang (MUX/DEMUX),si quang,cc b khuch i quang (EDFA),cc b ni cho quang (OXC), cc b tch knh xen r quang (OADM), chuyn mch quang v cc b lc,.... Ngoi ra, cn c thm cc h thng knh tn hiu iu khin gim st v h thng qun l. xviWDM/OTNVoice, IP...ATM SDH Voice, IP...MPLS Giao din quang m SDHATM IP ...WDM/OTNMng quang tng laiMng quang hin tiHnh 1.6 Xu hng mng truyn ti quang trong tng lai OADMHnh 1.7 Cu trc ca mt h thng WDM n gin Ngun pht:Ngun pht s dng trong cc h thng WDM thng l lasernhsdngtrongcchthngkhongcchlnthngthng. Tuy nhin, chng phi p ngc cc yu cu nghim ngt hn. B thu: B thu c chc nng bin i tn hiu quang thnh tn hiu in v phi hon ton tng thch vi b pht c v bc sng v cc c tnh iu ch. C 2 loi b thu thng c s dng cho cc h thng WDM l diode PIN vphotodiodethc APD.PINhotngvinguncngsut thp hn (5V) nhng li c nhy thp v bng tn hp hn APD. APD ph hp cho cc ng dng c ly ln. Cc tham s c bn nh gi 1 b thu gm: p ng ph, nhy, bng tn ph v in, di ng v nhiu. Si quang:Si quang l thnh phn c bn ca mt mng quang. Si n mode chun (G.652) c bc sng tn sc bng 0 ti 1310nm v gi tr tn sc ln ti 1550nm (18ps/nm.km) hin nay vn c s dng lm mi trng truyn dn cho cc h thng WDM. Mc d c c tnh khngtng thch vi ca s EDFA ti 1550nm ny nhng cc php nh gi gn y cho thy rngloi siny c th dng cho cchthngWDM tc trungbnhm khng lm suy gim cht lng tn hiu qua cc khong cch ng k nu h thng c s dng si b tn sc hoc cc thit b b tn sc khc. Si tn sc dch chuyn, DSF, (G.653) tuy c tn sc bng 0 ti bc sng 1550nm nhng khng c khuyn ngh dng cho cc h thng WDM do hiu ng FWM. Si tn sc dch chuyn khc 0, NZ-DSF, (G.655) c gi tr tn sc nh vng ca s 1550nm, do vy hn ch c cc nh hng phi tuyn c bit l hiu ng trn 4 bc sng (FWM) i vi h thng l loi si c thit k cho cc h thngWDM. Loi si nyclngtnscnhtrongvngbcsngt 1530nm n 1565nm (t hn 3ps/nm.km ti 1530nm v xung cn nh hn 0,7 ti 1560nm). Gi tr ny loi b c hiu ng FWM m vn cho php truyn c cc knh c tc t nht 2,5Gbit/s qua khong cch 1000km. B khuch i quang: Mt trong nhng yu t to nn s thnh cng ca WDM dn n s ra i ca cc b khuch i quang pha erbium (EDFA). Thit b ny s dng nng lng t 1 laser bm khuch i tt c cc bc sng tn hiu c mt ti li vo ca chng. 1 EDFA gm 1 chiu di si quang c pha tp vi erbium , do vy chng c th bin i nng lng t pht x xvii OADMbm ring bit thnh cc bc sng n, tc l khuch i cc tn hiu. Vi 1 thit k EDFA n gin nht th s khuch i xy ra qua 1 vng bc sng tng i hp t 1525nm n 1565nm. Di 40nm cng x l 1 s lng ln cc knh quang. EDFA trong sut vi giao thc, dng, tc bit ca tn hiu, v trong gii hn no c vi bc sng tn hiu quang. Do , cc knh quang c th c xen hoc r trn tuyn ti bt c thi im no. Vic s dng EDFA cho php thit lp c cc h thng truyn dn c ly ln vi t cc thnh phn in t hn, tuy nhin cng lm xut hin 1 s vn mi. l vn v khuch i ph khng ng u v nhiu pht x t pht khuch i (ASE). Cc nghin cu mi v nguyn l bm EDFA cng sut ln tp trung vo vic m rng vng khuch i ca cc EDFA t 1570 n 1630nm- tc l bng L. Cc b ghp knh xen r quang: B OADM c cc giao din quang hai hng ng v Ty, cng nh cc cngXenvRchohai hngngvTycaOADM. Cclungquang ng-Ty v Ty-ng bao gm tn hiu quang ghp knh theo bc sng bao gm N sng mang. B OADM cho php tch v chn mt sng mang (ti bc sng j) trong cc lung quang ng-Ty v Ty-ng. Cc bc sng cn li ca lung ghp knh s c cho qua b OADM m khng b tc ng g. Cc cng Xen v R c th cn ti b pht p chuyn i bc sng hoc giao din thch nghi quang ca cc h thng khng theo khuyn ngh G.691.xviiijj1... N1... N1... N1... N OADMTy ngHnh 1.8 Cu trc b ghp knh xen r quang Cc chc nng khc ca OADM l:B tn sc.iu chnh mc cng sut (khuch i/suy hao).Chn, tch v x l cc thng tin mo u ca ghp knh phn on quang (nu cn ti giao din thch nghi quang, v d G.957 ti G.mcs). Chn, tch v x l cc thng tin mo u ca ghp knh phn on quang. Tch, chn,v x l cc thng tin mo u catruyn dn phn on quang.H tr knh gim st v cc knh thng tin ngi s dng.Kim sot tn hiu quang. Thit b ni cho quang:xix1... N1... NHnh 1.10 Thit b ni cho quang.j...kj...k1... N1... N...1... N1... N...M si u vo M si u raLp OTSLp OMSOTSOMSOTSOMSOTSOMSOTSOMSHnh1.9 Cc chc nng ca OADM theo m hnh phn lpThit b ni cho qang (OXC) c M si u vo, M si u ra v cc cng xen r. Mi si u vo v u ra mang mt tn hiu ghp knh N bc sng. Cc cng xen v r cho php chn v tch mt s bc sng.OXC thc hin cc chc nng sau y: ghp v tch knh, ghp knh xen r, chuyn mch khng gian, v c th l c chuyn i bc sng. iu ny cho php thc hin ni xuyn cc tn hiu quang gia cc si u vo v u ra (v c th ni xuyn gia bc sng vo v bc sng ra).Cc chc nng khc ca OXC l:B tn sc.iu chnh mc cng sut (khuch i/suy hao).Chn, tch v x l cc thng tin mo u ca ghp knh phn on quang(nucnti giaodinthchnghi quang, v dG.957ti G.mcs).xxLp OChLp OTSLp OMSOMSOMSOMS OMSHnh 1.11 Chc nng ca OXC theo m hnh phn lpOTS OTSOTS OTSOCh OCh OChOCh Chn, tch v x l cc thng tin mo u ca ghp knh phn on quang. Tch, chn,v x l cc thng tin mo u catruyn dn phn on quang.Kim sot tn hiu quang. Cc b u cui ghp knh quang: Mt b u cui ghp knh quang (OTM) c biu din nh hnh 1.12.OTM l mt phn t mng hai chiu. Trong hng truyn i, n c kh nng tip nhn N knh quang, mi knh c mt mc cng sut tn hiu quang v t s SNR theo ch tiu k thut xc nh. OTM xc nh bc sng cho tng knh quang ti u vo theo cc bc sng c nh ngha t trc, v u ra thit b ny cha tn hiu ghp knh bao gm N bc sng (sng mang). Tn hiu u ra c trng bi bng tn quang tng, cng sut quang tng, cng sut mang trn mi sng mang v t s SNR ca mi sng mang.xxiCh N...Ch 2Ch 1Ch N...Ch 2Ch 11...N1...NHnh 1.12 Cu trc b ghp knh quangTrong hng thu, b OTM nhn tn hiu ghp knh theo bc sng, tch tn hiu thnh cc sng mang nh u vo b ghp knh, v a N knh quang ti cc u ra ring bit.Bc sng ca tng knh quang c th thay i so vi khi n c chn vo hay tch ra t cc b ghp/tch knh. V th, trong OTM c th cn n mt b chuyn i bc sng. iu ny c bit c ngha nu c mt s h thng SDH cng tn ti (giao din quang G.957) c ghp knh cng vi nhau, trong trng hp , cc bc sng ca mt vi h thng s phi thay i cho ph hp a vo cc knh ca OTM. Hin ti vi cng ngh ny, vic thay i bc sng c thc hin ch yu nh b chuyn i O/E/O. Cc b chuyn i bc sng photonic t c s dng hn. Thay i bc sng c th c thc hin nh b pht p ng c lp, tch bit vi b ghp knh ca n.Cc chc nng khc c th c ca OTM l:B tn sc.iu chnh mc cng sut (khuch i/ suy gim).Chn, tch, v x l cc thng tin mo u ca lp knh quang (nu cn n giao din thch nghi quang, v d: G.957 hoc G.mcs).Tch, chnvxlccthngtinmoucaontruyndn quang.H tr cc knh gim st v knh thng tin ngi s dng.Kim sot tn hiu quang.C hai cu hnh c bn truyn dn dng cho h thng WDM: Cu hnh truyn dn hai hng trn cng mt si quang: cu hnh ny, cc knh quang c hai hng truyn dn (i v v) c ghp chung ch trn mt si quang. Cu hnh ny cn c gi l cu hnh h thng truyn dn song cng. Cu hnh truyn dn hai hng trn hai si quang: cu hnh ny, theo mi hngtruyndn,cc knhquang cghptrnmt si quang ring bit v mi si quang m nhim truyn dn ch theo mt hng (i hoc v). i khi, cu hnh ny c gi l cu hnh h thng truyn dn n cngxxiiV mt phttrin v ng dng,h thng WDM n cng c s dng tng i rng ri, cn h thng WDM song cng th c nhng yu cu cao hn, l v trong thit k v ng dng h thng WDM song cng cn phi xem xt n cc yu t then cht ca h thng nh hn ch can nhiu nhiu knh (MPI), cn ch n cc vn nh hng ca phn x quang, cch ly gia cc knh hai chiu, tr s v loi hnh ca xuyn m, cng sut tn hiu quang truyn dntrnhaichiu..., ngthi phisdngbkhuchiquanghai chiu. Nhng so vi h thng WDM n cng, h thng WDM hai chiu gim c s lng b khuch i quang v ngdy.xxiiiCHNG II BO V TRONG MNG TRUYN TI QUANG WDM2.1 S cn thit phi bo v tng quangHat ng bnh thng ca mt mng truyn ti quang trong thc t khng nhng nh hng bi nhng yu t khch quan nh tin cy, tui th ca thit b m cn chu tc ng ca cc yu t mi trng, kh hu, thi tit, cc nhn t ch quan do con ngi gy ra. Tc ng ca cc yu t trn gy ra s c hng thit b, t cp dn n s ngng hot ng ca cc knh truyn ti thng tin gy thit hi cho c ngi s dng v ngi cung cp dch v. Vn t ra l cn phi thit lp chc nng duy tr hot ng ca mng trc cc s c bng cch p dng cc k thut bo v hoc phc hi mng. i vi mng truyn ti quang s dng cng ngh SDH, cc gii php k thut bo v v phc hi c p dng tng i hiu qu theo cc xut v khuyn ngh ca ITU-T [6]. Nhng thi gian hi phc li lu, vo khong t 60 ti 100ms. Trong khi th cc k thut bo v tng quang WDM c kh nng hi phc mng ch mt ti a 50ms. Tuy nhin, trong hin tai v tng lai, nhu cu lu lng ln i hi cn phi cung cp mt mi trng truyn dn dung lng ln, m cng ngh ghp knh theo bc sng WDM l mt trong nhng gii php c la chn. Do vy, vic xy dng chc nng phc hi mng WDM tng quang l vn sng cn cn phi gii quyt khi xy dng mng WDM nhm duy tr hot ng lin tc ca mng.Theo G.872 ITU-T, lp quang c chia thnh 3 lp con: lp knh quang (OCh-Optical Channel), lp on ghp knh quang (OMS Optical Multiplex Section) v lp on truyn dn quang (OTS Optical Tranmission Section). Bo v c th c thc hin ti lp OMS hoc lp OCh hoc phi hp trn c hai lp.xxivBo v OMS v bo v OCh c th theo phng thc ring hoc chung. Trong bo v ring, mi knh lm vic c truyn trn hai tuyn khc nhau v knh c cht lng tt nht s c la chn ti u thu, do vy mt na ca dung lng truyn dn trong mng s lun c n nh l dung lng d phng dnh cho bo v (tc l dung lng bo v bng 100% dung lng lm vic). Tri li, trong bo v chung, ti nguyn bo v c th c s dng phc hi nhiu knh lm vic khc nhau, tu thuc vo s c. Bo v chung cho php s dng dung lng mng tt hn bo v ring (lng dung lng d phng yu cu ph thuc nhiu vo topo mng v vo s phn b lu lng gia cc node).Hin nay, bo v ring OMS ch yu c trin khai trong cc h thng thng tin quang WDM im - im, cn bo v OCh c s dng c trong cc hthngim- imvccringOADM(Optical AddDropMultiplexer). Trong tng lai gn, cc ring bo v chung OMS s c th c trin khai.Bo v OCh c th c trin khai vi hai cch: bo v kt ni mng con (SNCP) hoc bo v lung. S khc nhau c bn l trong bo v lung OCh kt cui ca lung OCh cng c bo v v s lng card transponder c nhn i. Gii php ny ci thin sn sng ca knh quang, nhng li lm tng chi ph u t thit b.2.2 Cc khi nim c bnBo v l mt phng thc hi phc mng s dng cc ti nguyn bo v c cp pht trc truyn lu lng ti hot ng trn knh b nh hng bi s c nhm m bo kh nng duy tr ca mng.Bo v - C nhiu tiu chun phn loi cc k thut bo v mng nhng thng da trn cc tiu chun ph bin sau: Da vo s lng h thng lm vic v d phng Bo v 1+1: l bo v m trong dnh ring mt h thng d phng bo v cho mi h thng hot ng. Bnh thng c hai h thngcngcsdngnhngch lykt qucatuynhot ng, khi xy ra s c th chuyn sang h thng d phng. Bo v M:N: l bo v m ta chia s M h thng d phng bo v cho N h thng hot ng cng chng loi. Khi xy ra s c xxvtrn bt k h thng hot ng no th chuyn mch bo v sang mt h thng d phng kh dng. tit kim ti nguyn ta c th s dng M h thng d phng ny cho cc mc ch khc nh: hot ng th nghim dch v mi hoc x l cc cng vic ph c mc yu tin thp. Da vo cu trc h thng bo v ta c chuyn mch bo v n hng hay c hai hng, loi tr v hay khng tr v; chuyn mch bo v tuyn (PPS) hay bo v on (LPS) Chuyn mch bo v n hng: ch lu lng trn hng truyn dn no c s c th mi chuyn mch bo v sang knh d phng, cn cc tuyn khc khng c s c th gi nguyn. Chuyn mch bo v hai hng: nu c bt k mt hng hot ng no b s c th c hai hng cng chuyn mch bo v sang knh d phng (knh bo v). Bo v c tr v: sau khi chuyn mch bo v sang knh d phng m khi phc li ng truyn s c th lu lng t ng chuyntknhbov v knhhot ngckhi phc. Phng php bo v ny thng p dng cho bo v chia s N:M. c bit l 1:N. Bo v kiu khng tr v: sau khi chuyn mch bo v sang knh d phng m khi phc li c ng truyn s c th vn truynlulngtrnknhdphng. Phngphpbovny thng p dng cho bo v ring 1+1. Bo v tuyn: ch thc hin chuyn mch bo v ti im kt cui ca tuyn c s c. Bo v on: thc hin chuyn mch bo v ti hai nt k cn vi on b s c, trng hp s c nt th on b s c l hai on lin nhau cha nt .2.2.1 Bo v ringBovringlhnhthcbovmtrongmi knhlmvicc truyn trn hai tuyn khc nhau v knh c cht lng tt nht s c la chn xxviti u thu, do vy mt na ca dung lng truyn dn trong mng s lun c n nh l dung lng d phng dnh cho bo v (tc l dung lng bo v bng 100% dung lng lm vic).Trong bo v 1+1, nt ngun pht tn hiu ng thi trn c hai tuyn hot ng v bo v. Nt ch gim st tn hiu ca c hai tuyn ny v la chon tn hiu c cht lng tt nht (v d da chn tham s SNR). Nu pht hin suy gim tn hiu trn tuyn hot ng th nt ch t ng chuyn mch sang tuyn bo v. Trong bo v 1:1 nt ngun ch pht tn hiu ln tuyn hot ng, cn tuyn bo v c th c dng truyn lu lng c mc u tin thp. Khi xy ra s c trn tuyn hot ng th c nt ngun v nt ch chuyn mch ln tuyn bo v.V d trong mt mng vng bo v 1+1 s dng cc knh quang kp, tn hiu c pht i trn hai knh: mt knh truyn theo hng thun chiu kim ng h, cn knh kia truyn theo hng ngc chiu kim ng h; my thu s la chn tn hiu tt nht. Nu hot ng ny c thc hin lp knh quang th ta gi l OC-DPRing (p dng cho ring 2 si 2 hng), nu thc hin lp ghp knh quang th ta gi l OMS -DPRing (p dng cho ring 4 si 2 hng).Trongccmngli xydngcclinkt im-imtruynti hai hng mun cung cp bo v ring th phi s dng hai cp si tch bit nhau v mt vt l, mt cp cp cho cc knh hot ng cn cp kia cp cho cc knh bo v, khi xy ra s c trn si hot ng th chuyn cc knh lu lng ln si bo v.2.2.2 Bo v chia sBo v chia s l hnh thc bo v m trong nhiu h thng hot ng cng s dng chung mt h thng d phng bo v. Chng hn l dung lng d phng hoc bc sng d phng. iu kin bnh thng mi yu cu c nh tuyn ln cc knh hot ng, v dung lng bo v c th c dng truyn lu lng c mc u tin thp. Khi xy ra s c lu lng ti ca tng tuyn truyn dn b s c c chuyn mch ln cc bc sng bo v. Hot ng ny yu cu h tr bo hiu thng bo cho cc nt mng v cc tuyn ng truyn dn b s c th mi m bo chc chn cc bc sng bo v trn cc si khc nhau kt ni chnh xc ti cc tuyn quang yu cu bo v. Trong xxviithi gian ti nguyn d phng c dng bo v mt tuyn hot ng b s c th n khng cn kh dng bo v cho cc tuyn quang hot ng khc cho ti khi tuyn hot ng ban u ny c khi phc li.i vi cc vng ring quang bo v chia s, dung lng ca cc si dnh cho cc knh hot ng v bo v l ring bit. Do mt ring 2 si bo v chia s l ring 2 hng, mt si truyn lu lng theo hng thun chiu kim ng h, cn si kia truyn lu lng theo hng ngc chiu kim ng h.Tng t vi cc mng li quangbo v chia s (trong cc lin kt im - im): trong mi cp si, mi si s dng mt na s knh cho lm vic, v dnh mt na s knh cn li bo v cho lu lng lm vic trn si kia. Nu mt si b s c th cc knh hot ng s c truyn trn cc knh bo v ca si kia.Bo v chia s l mt cch gim dung lng tha dnh cho d phng v gim s lng cc tuyn quang cn phi qun l.Hin nay mi ch p dng bo v ring OMS cho cc h thng WDM im - im, trong khi bo v OCh c s dng cho c h thng im - im v cc ring OADM, sp ti c th s cung cp thm cc ring bo v chia s OMS.2.2.3 Bo v on ghp knh quangHnh thc bo v ny c thc hin lp ghp knh quang (OMS), v hay cpdngbovtrongccmngcungcpmt slnglnccknh quang. Tt c cc bc sng (knh WDM) truyn trn si quang b s c cng cnhtuynlilnmttuynsiquangtmthiri(cxcnh trc). Thchinchuynmchbovkhnggianti bghpknhWDM (chuyn mch si quang).2.2.4 Bo v knh quangHnh thcbo v nyc thcthi lpknh quang.Miknhquang cbovclpsdngmt chuynmchring, dnntngscc chuyn mch quang ln nhng cho php la chn cc knh bo v trong b ghp knh v c th tch hp bo v ca cc b pht p vo trong kin trc ny.xxviiiSi hot ng Si d phngSi d phng chuyn sang hot ngHnh 2.3 OCh DPRing hai si n hng iu kin bnh thng v khi c s cChuyn mchChuyn mch2.3 Cc phng thc bo v theo cu hnh mng2.3.1 Bo v lp knh quang2.3.1.1 Bo v ring cho cu hnh im - imVi cuhnhnycthpdngtrctipcckthut bovtuyn ring/chiasnnkhngcnphntchnhiu. Mcdcuhnhnyngin nhng n thng hay xy ra s c nh t c tuyn cp hay s c hng thit b nn n ch c s dng giai on u th nghim cha pht trin dung lng m khng my khi c s dng trong cc mng quy m ln. Trong trng hp s dng kiu bo v ny th cch phng hiu qu nht l chn tuyn ng i cp thun li hn ch ti thiu kh nng b xm phm, c chnh sch bo dng thng xuyn, v p dng k thut bo v 1+1 hay 1:1. Bo v quang 1+1 tng t nh phng thc bo v 1+1 SDH. Pha pht s dng b chia s chia cng sut quang v pht trn c hai tuyn hot ng v d phng; pha thu s dng mt chuyn mch quang c chc nng nh mt b la chn v chuyn mch ln tuyn bo v khi tuyn hot ng tng t c s c.Bo v quang 1:1 tng t nh phng thc bo v 1:1 trong SDH. Khc vi bo v 1+1, lu lng khng c truyn trn c hai si hot ng v lm vic m s dng chuyn mch c hai u. Ban u chuyn mch t ln si hot ng, khi pht hinscth chuynmchlulnglnsi bov. Trng hp ny yu cu phi c knh bo hiu APS kch hot chuyn mch bo v.xxixSi hot ngSi bo vRxTxB chia Chuyn mchHnh 2.1 H thng WDM cu hnh ng thng chuyn mch bo v 1+1Si hot ng Si d phngSi d phng chuyn sang hot ngHnh 2.3 OCh DPRing hai si n hng iu kin bnh thng v khi c s cSi hot ng Si d phngSi d phng chuyn sang hot ngHnh 2.4 OCh DPRing bnsi n hng iu kin bnh thng v khi c s cSi bo vChuyn mchKnh bo hiu APSChuyn mchRxTxHnh 2.2 H thng WDM cu hnh ng thng chuyn mch bo v 1:1Si hot ngim khc bit gia bo v WDM v SDH l khi xut hin s c trn mt si hot ng th chuyn mch ca u thu tng ng ca pha pht khng bit g (chuyn mch b m blind switch), trong khi SDH c hai u thu u bit trng thi ca si bo v.2.3.1.2 Bo v ring cho cu hnh ring (OCh - DPRing)Bo v trong cu hnh ny c thc thi lp knh quang s dng cc chuyn mch quang chuyn mch lu lng ln si hot ng hay bo v ty thuc vo trng thi ca ring iu kin bnh thng hay s c m khng yu cu bo hiu. Kin trc bo v ny c th chng li s c chng n, s c a chng, hay s c ti nt trung gian trn tuyn hot ng. Nhng c nhc im chung l yu cu chi ph t hn so vi cc gii php khc.Trng hp ring hai si cp pht mt si cho hot ng v dnh mt si d phng bo v cho si hot ng. Ti my pht tn hiu quang c chia thnh hai lungtn hiuv nhtuyn trn haituynkhc nhau (nh trong bov 1+1). My thu nhn c hai tn hiu ri la chn tn hiu tt nht. Khi si hot ng xy ra s c, u thu tng ng t ng chuyn mch bo v ln si d phng. xxx B ghp knh B khuch iNt ANt DNt B Nt CNt ANt DNt B Nt CSi hot ng Si d phngSi d phng chuyn sang hot ngHnh 2.3 OCh DPRing hai si n hng iu kin bnh thng v khi c s cHnh aHnh bSi hot ng Si d phngSi d phng chuyn sang hot ngHnh 2.4 OCh DPRing bnsi n hng iu kin bnh thng v khi c s cCc nt trong mng l cc OXC v trn mt si ta c th truyn n hng hoc hai hng, nhng trong trng hp OCh DPRing hai si mt si cho d phng v mt si cho hot ng th ta phi truyn hai hng. Vi d nh hnh 2.3, hnh a tnh trng cha xy ra s c, hnh b tnh trng s c. Trng hp OCh DPRing bn si (trong hai si dnh cho lu lng hot ng, cn hai si dnh cho d phng ). trng hp ny nu truyn lu lng hai hng th s thc thi bo v 1+1 mm do hn v yu cu t bc sng hn trng hp OCh DPRing hai si nhng li tn km. V d v OCh DPRing bn si n hngc m t trong hnh 2.4, hnh a tnh trng cha xy ra s c, hnh b tnh trng s c. Gi s ta c mt mng vng ring su nt, mi nt yu cu nm bc sng truyn thng vi nm nt kia nu khng ti s dng bc sng th tng bc sng yu cu ln ti 15. Tng qut mt mng OCh DPRing bn si c N nt s yu cu 2) 1 .( N N bc sng. Nu cho php s dng li cc bc sng, v d cc on k nhau c th chia s cng bc sng th tng s bc sng gim xung 3 nhng yu cu thc thi chuyn mch bo v c hai u cui trnh xung t bc sng trn si bo v khi xy ra s c.xxxi B ghp knh B khuch iNt ANt DNt B Nt CNt ANt DNt B Nt CSi hot ng Si d phngSi d phng chuyn sang hot ngHnh 2.4 OCh DPRing bnsi n hng iu kin bnh thng v khi c s cHnh a Hnh bTX 1 TX n TX 1 TX nM hnh chc nng ca OCh DPRing c th tham chiu m hnh bo v ring on ghp knh SDH (MS SPRing) vi gi thit khng thc thi bo v tng SDH m bo v mc knh quang.2.3.1.3 Bo v chia s cho cu hnh im - imChia s l mt cch gim dung lng tha dnh cho d phng v s lng cc tuyn quang cn phi qun l.Trong bo v chia s knh quang (chia s tuyn), thi im thit lp phin lin lc cho mt ng ban u, xc nh mt ng d phng v mt bc sng dnh ring. Mt tuyn quang bo v gia hai nt c thit lp bo v cho N tuyn quang hot ng gia hai nt . xxxiiHng ngHng tyHinhg 2.5 M hnh chc nng ca mt nt OCh DPRing Lp OTSLp OMS B ghp knh B khuch iLp OChLp SDH hoc ATM hoc IPTX 1 TX n TX 1 TX nBc sng d phng dnh ring trn cc on ca ng d phng c th chia s vi cc ng d phng khc gip cho gii php ny c chi ph hiu qu hn bo v tuyn ring nhng cng yu cu nhiu bo hiu hn v phi cu hnh li cc OXC kt cui ca cc knh WDM chia s m tuyn hot ng cn c hi phc. iu ny s lm tng thi gian tr hi phc thc hin truyn cc bn tin bo hiu ti cc thnh phn v cu hnh li tt c cc OXC.2.3.1.4Bo v chia s cho cu hnh ring (OCh - SPRing)Xt ring hai si truyn thng hai hng gia cc nt. Trong iu kin bnh thng, mi si hot ng trn mt bc sng khc nhau (1thun chiu kim ng h v 2 ngc chiu kim ng h). Nu mt on hay mt nt b s c th cc nt k cn s nh tuyn li cc bc sng cho on cung b , chia s dung lng ca cc si gia hai knh quang. OCh SPRing thng c dng cung cp bo v quang cho cc ring SDH hai si. Vic nh tuyn lu lng lin quan c thc hin lp in bi thit b SDH, cc knh quang ch tn ti gia cc nt k nhau tng ng vi cc on vt l nt - ti - nt. V d truyn thng gia hai nt A v nt D nh hnh v 2.7, hnh a tnh trng cha xy ra s c, hnh b tnh trng s c. Nh trnh by trn th1 c truyn trn si quang th nht thun chiu kim ng h, 2 truyn trn si thhai ngcchiukimngh. Khi xyrasconth nt Atng chuyn mch bo v bc sng 1 ln si quang th hai ngc chiu kim ng h. xxxiii B ghp knh B khuch i...TX 1 TX n... TX 1 TX nKnh bo hiuHnh 2.6 Mng li WDM bo v chia s 1:NV d truyn thng gia nt A v nt C v xy ra s c nt D. Hnh v 2.8 di y m t:OCh SPRing thng c dng cung cp bo v quang cho cc ring SDH hai si. Vic nh tuyn lu lng lin quan c thc hin lp in bi thit b SDH, cc knh quang ch tn ti gia cc nt k nhau tng ng vi cc on vt l nt ti nt.M hnh chc nng ca OCh SPRing tham chiu m hnh bo v SDH MS SPRing nhng mc knh quang. Do cc chc nng thch ng tng OTS v OMS phi x l cng mt s lng cc knh quang nn chuyn mch bo v khng th t tng OMS m c chuyn ln tng OCh.Hnh v di y miu t m hnh chc nng ca mt nt OCh SPRing k cn vi s c s dng xxxiv B ghp knh B khuch i111Hnh 2.7 OCh SPRing khi bnh thng v khi s c on21Nt DNt CNt BNt AHnh a2221Nt DNt CNt BNt AHnh b22121Hnh 2.8 OCh SPRing khi bnh thng v khi s c nt 21Nt DNt CNt BNt AHnh a2121Nt DNt CNt BNt AHnh bchuyn mch OCPC mc knh quang, cn cc hot ng nh tuyn c thc hin cc tng SDH (HP, LP).2.3.1.5 Bo v chia s cho cu hnh MeshD cu trc mng Ring WDM l cu hnh ph bin nht hin nay, nhng gn y cc mng quang WDM c cu hnh Mesh ang c tha nhn l c c tnh quan trng v u vit hn. iu ny l nh s pht trin v ci thin ca cc OXC, cc thit b chuyn mch quang.Mc d mng quang cu hnh Mesh c nhiu u vit v ang c pht trin mnh nhng kh nng tn ti v duy tr mng l vn phc tp hn so vi cu hinh Ring bi v trong mng c nhiu thc th hn trong bng nh tuyn v c nhiu quyt nh thit k phi la chn. Ngoi ra, khng c c ch bo v mng quang WDM cu hnh Mesh no hin nay c thng mi ho trn phm vi ln. Bo v tuyn ti lp OCh c th c p dngcho cc mng quang cu hnh Mesh. c mt kt ni th mt cp ng i (ng i lm vic v ng i d phng) phi c thit lp. c ch bo v tuyn t hiu qu nht th cc tuyn lm vic v cc tuyn bo v phi c lp, c lp c v s c (ngha l cc li tuyn xy ra trn tuyn hot ng v tuyn bo v l c lp). Trong xxxvHng tyOCPCHnh 2.9 M hnh chc nng ca mt nt OCh SPRing k cn vi s c B ghp knh B khuch iLp OTSHng ngLp OMSLp OChLp SDHnhiu trng hp, iu kin ny c tha mn bng vic thit lp hai ng i trong phn tp cc ng i vt l: ng i chnh v ng i phc hi khng th dng chung bt k mt lin kt no. Nu vn bo v nt c t ra th s c lp gia nt v nglm vic, ng bo v l cng cn thit. Trong hu ht cc trng hp th iu ny c bo m bng vic ngn cn dng chung hai ng i trong mt nt: nh tuyn phi c thc hin di cc rng buc v vic khng lin hp nt. Bo v tuyn dnh ring 1+1 v bo tuyn 1:1 u c th c s dng.Trong trng hp bo v 1:1 lu lng c u tin thp c th c pht trn tuyn bo v khi khng c li xy ra, nhng bo hiu t u cui ti u cui l cn thit. Vi cuhnhMeshth bovtuyndnhringtiutnti nguynqu nhiu bi v phi c cc rng buc ng i vt l. Vic dng chung cc knh WDM(ccbcsngquang)trongsccngibovcthgimti nguyn vt l tham gia trong vic bo v. Vic bo v dng chung c th c p dng theo ngha t u cui ti u cui bng vic s dng mt tuyn bo v(c th c mt nt dng d phng) cho N tuyn hot ng vi cng cp nt ngun ch (xem hnh 2.10 di y). K thut ny l mt trng hp c bit ca vic dng chung, trong N tuyn bo v chia s tt c cc knh WDM ca chng, v cng c gi l bo v 1:N. Hin nhin bo v 1:N ci m cn N+1 tuyn khng lin hp ng (hay khng c s lin hip nt) l lun c th s dng gia cc nt ngun v ch ca kt ni.xxxving hot ngng bo vHnh 2.10 Bo v ng trong cu hnh MeshchNgungBo v ng chia s cng c th c thc hin mt chiu hng rng hn trn mt mng hn hp bng vic cho php dng chung mt phn (thng l di tn s nh sng) cc ng bo v trn c s ghp cc bc sng. Vic chia s cho php tit kim cc ngun ti nguyn truyn dn, nhng li yu cu qun l phc tp. Trong bo v 1:1 v 1:N, khi mt s c xy ra th ch cc nt cui mi lin quan ti qu trnh hi phc, bi v cc knh quang (cc bc sng ) c bo v v cc knh quang d phng l hon ton c thit lp trc. Khi bo v chia sc p dng hng rng hn trong mt mng c cu hnh Mesh, th s c s phi lm th tc phc hi phc tp hn, th tc yu cu nhiu bo hiu trong mt s phn t mng dn n thi gian phc hi s tn km. Khng nhng phi c nhiu tn hiu bo hiu m trong vn phc hi mng cn phi mt thi gian cu hnh li cc OXC(ngha l thay i cc thng s nh tuyn).Do vic bo v dng chung l nh trc, nn hot ng khi phc c th c iu khin bng ng phn phi no hn l ng tp trung, bi vy loi b c s can thip ca h thng qun l mng v gim khi lng bo hiu. Trong trng hp ny, cc OXC phi c kh nng t xc nh ng ang lm vic c s c hay khng chuyn mch bo v cho ph hp. Vic u tin yu cu l phi pht hin nhanh chng c trng ng nh sng v l mt trong cc thc y chnh m nh ngha mt b nhn dng OCh trong khun kh ca vic chun ha knh gim st OCh.Nu bo v chia s tuyn s dng iu khin phn tn thay cho iu khin tp trung s hn ch s can thip ca h thng qun l mng v gim bt tng s cc bo hiu. Khi cc OXC phi c kh nng t nhn thc c tuyn hot ng no b s c chuyn mch bo v ph hp. Trong cc mng quang WDM cu hnh Mesh, bo v tuyn lp con OMS di mt vi phng din c th thch hp hn l vic bo v ng. Trong mt cu hnh phc tp, mt c cu khi phc ni b, ph hp vi iu khin phn tn hn l iu khin tp trung, l d dng qun l hn mt c cu u cui ti ucui.Bo v tuyntrongmtmng hnhp cth xy ra trong cc ng khc nhau. Chng ta s khng xem xt bo v ng trn c s cung cp m chng ta s m t hai phng php chnh c bit n bo v tuyn nh xxxviiSi hot ng Si d phngSi d phng hot ngtrc: mt l da trn khi nim u vng cc vng, cch cn li gn y c cp nhiu hn, l da trn cng ngh u vng chung.Mt mng cu hnh Mesh c th c to mt cch t nhin bng lin kt n gin mt s vng: thc t, hu ht cc mng WDM hin nay c qun l theokiuny. Chuynmchgiaccvngtrongccmngnhvythng c thc hin bng in t bi cc ni cho s SDH/SONET.Bi vy,kh nng tn ti trong cc mng a vng WDM thng c bo v bi cc k thutbov SDH/SONET (cth, lkhai thc sthacacc lin ktlin vng). Mt s trong nhng k thut ny s c th cng chuyn ti lp WDM (v d cho trng hp c th a vng WDM di bin). Tuy nhin, trong nhng th sau y, chng ta mun b kin trc a vng v tp trung vo cc mng WDM thc t, ngha l nhng mng ny c to rabt u t mt cu hnh vt l hn hp v ci m khai thc cc OXC thc hin chuyn mch quang trong ton b mng. S phn ly vng cc kin trc c s ca tng lai ny ch phc v kh nng tn ti.Nguyn l u vng cc vng c th c p dng mt mng WDM thc t nh sau: u tin, mng ny c phn tch trong mt s tp cc cp, mi tp c qun l nh mt vng n. Khi phn tch c thc hin, mi vng c trang b mt h thng bo v OMS chnh xc nh mt OMS-SPRing. Bi vy mi vng tr thnh mt h thng bo v.Thng thng vic thc hin bo v vng bn cp l la chn tt nht, t vic thc hin bo v vng 2 cp phi yu cu cc b chuyn i bc sng trong mt s node. Mt u im r rng ca phng php ny l n cho php khi phc phn b: mi vng l mt h thng khi phc t ng v t tr. iu ny ng rng thi gian khi phc ch b gii hn bi kch c vng (trong bo v tuyn, thay v tr truyn lan t ngun ti ch phi a ch tnh n). Hn na, vic qun l s c b gii hn bi vng b s c.Trong vn bo v mng c cu hnh Mesh ni chung v bo v mng quang WDM c cu hnh Mesh ni ring l nhng vn mi m v phc tp. Ni cch khc th lnh vc ny khng c thng mi ho v ng dng trong thc t nn khng c my ai nghin cu v lnh vc ny cho nn n vn cn mi m. Ngoi ra n cn mt l do khc l iu kin vt l v nhu cu ca cc quc xxxviiiB ghp knh B khuch iSi hot ng Si d phngSi d phng hot ng Cc knh bo vCc knh dch v vv Cc knh bo vCc knh dch v vv Cc knh bo vCc knh dch v vv Cc knh bo vCc knh dch v vvvvvvgia vn cha i hi cn n s dng mng li c cu hnh Mesh. Trong khi cng ngh WDM ch yu c s dng cho cc mng c cu hnh back blbole. V vy trong n ny em cpt n vn .2.3.2 Bo v lp on ghp knh quang2.3.2.1 Bo v ring cho cu hnh im - imTrong bo v on ghp knh quang vi cu hnh im - im th chnh l hnh thc bo v knh quang im - im.2.3.2.2 Bo v ring cho cu hnh vng ring (OMS - DPRing)OMS DPRing c th p dng cho ring hai si hoc bn si cp pht cc bc sng khc nhau cho cc lin kt nt - ti nt khc nhau. Bo v c thc thi tng on ghp knh quang nn tt c cc knh quang trn cng mt chng s c bo v ng thi khi xut hin s c. Khi xem xt bo v OMS gia cc OADM trong mt kin trc ring yu cu phi s dng cc chuyn mch kp hoc cc chuyn mch n c h tr bin i bc sng ti mi nt.Xt trng hp n gin nht OMS DPRing hai si s dnh ring mt si bo v cho lu lng truyn trn si hot ng hng ngc li.Khi xut hin mt s c nt hay s c on, cc nt k cn vi s c s nh tuyn li lu lng t trn si hot ng ln si bo v. Di y l m hnh chc nngca mt nt OMS DPRing.xxxixB ghp knh B khuch iHng tyHnh 2.12 M hnh chc nng ca mt nt OMS DPRing hai siLp OTSLp OMSLp OChHng ngSi hot ng Si d phngSi d phng hot ngHnh bNt DNt CNt BNt ANt DNt CNt BNt AHnh 2.11 OMS DPRing hai si iu kin bnh thng v khi c s cHnh a Cc knh bo vCc knh dch v vv Cc knh bo vCc knh dch v vv Cc knh bo vCc knh dch v vv Cc knh bo vCc knh dch v vvvvvv2.3.2.3 Bo v chia s cho cu hnh vng ring (OMS SPRing)Kin trc ny c th p dng cho ring hai si hoc bn si. Cc lin kt logic trc tip nt - ti - nt c th c thit lp s dng cc bc sng khc nhau, cho php ta xy dng nn cc li logic kt ni mi nt ti nt khc trong ring.Bo v c thc thi mc on ghp knh, dung lng ca mi si mang c cc bc snghot ng v bc sng bo v. V d mt h thng WDM hai si c 16 bc sng, trn si truyn cng chiu kim ng h cp mt na u (8 bc sng) ca di bc sng cho cc knh lu lng hot ng, mt na cn li dng bo v cc knh hot ng truyn trn si kia (i ngc chiu kim ng h). Trn si i ngc chiu kim ng h th o ngc li, na u ca di bc sng dng bo v cc knh hot ng truyn trn si i cng chiu kim ng h, cn na sau dng cho cc knh lu lng hot ng khc.xl Cc knh bo vCc knh dch v vv Cc knh bo vCc knh dch v vv Cc knh bo vCc knh dch v vv Cc knh bo vCc knh dch v vvvvvvHnh 2.13 Bo v chia s cc knh quang trong OMS - SPRingNu mt on hay mt nt b s c, cc nt k cn s c thc hin chuyn mch bo v nh tuyn li cc bc sng hot ng truyn trn si b s c ln cc bc sng bo v ca sii theo hng ngc li. OMS 2 SPRing cho vng ring hai si hai hng.Trn si th nht cc bc sng lm vic t 1 ti W/2, na cn li dnh cho bo v. Trn si th hai cc bc sng lm vic t W/2 ti W, na cn li dnh cho bo v. Khi hi phc c thc hin bi chuyn mch 22. Trong trng hp lu lng b s c c th loop m khng b xung t bc sng xliChuyn mch 22Hnh 2.15 Ring hai si hai hng chuyn mch bo v on ghp knhHnh 2.18 M hnh chc nng ca mt nt OMS SPRing hai si k cn vi s c B ghp knh B khuch iSDXCSDXCKhi xut hin s c on, cc tuyn hot ng c nh tuyn ln cc si bo v cng bc sng hot ng. Khi xut hin s c nt th OMS 2 SPRing c thc thi bi chuyn mch 22. Bnh thng tuyn hot ng c nh tuyn ln ring ca si pha ngoi, sau khi xut hin s c nt th tuyn c chuyn mch ln ring ca si pha trong ti cng bc sng hot ng.Di y l m hnh chc nng ca mt nt OMS SPRing k cn s c s dng chuyn mch kp chuyn mch bo v pha xy ra s c (t cp hocscnt). MhnhnycxydngdatrnmhnhSDHMS xliiHnh 2.16 Ring hai si hai hng bo v s c on OMS 2SPRingHnh 2.17 Ring hai si hai hng bo v s c nt OMS 2 SPRingHnh 2.18 M hnh chc nng ca mt nt OMS SPRing hai si k cn vi s c B ghp knh B khuch iSDXCSDXCSPRing, ccchcnngthchngOMScxcnhtuthucvocch thng c th (v d chng ta s c chc nng OMSA 16 trong h thng WDM 16 bc sng) nhng n ch cung cp cho cc knh hot ng hoc bo v ch khng phi tt c 16 knh. Khi thit k thc thi cn xem xt n vic thc hin gim st cc s c nh th no nu ti s dng bc sng.Trong phng thc chuyn mch quang 22 th n thch hp vi chuyn mch bo v m yu cu tn tht nh (khong 1dB) v tc chuyn mch nhanh (khong 20 ms).Cu hnh nt bao gm mt OADM cho mt si, mt chuyn mch quang nhanh cho 22 mi pha ca nt, v c th s dng b khuych i quang nu cn. V tr tt nht t b khuych i quang l gia OADM v chuyn mch quang c th s dng cc b khuych i quang hn ch nhng tn tht ph trng thi bo v.Di y l cc cu hnh ca cc nt c s dng chuyn mch quang.xliiiHng tyHnh 2.18 M hnh chc nng ca mt nt OMS SPRing hai si k cn vi s cLp OTSLp OMSLp OChHng ngB ghp knh B khuch iLp SDH hoc IP hocATMEDFAEDFASDXCOADMOADMOS 2 OS 1Si 1Si 2Hnh 2.19 Cu hnh ca mt nt s dng chuyn mch quang22 (cross - bar)EDFAEDFASDXCOADMOADMOS 2OS 1Si 1Si 2OS 3OS 4Hnh 2.20 Cu hnh ca mt nt s dng chuyn mch quang 21Si bo v Si bo v ng bo v th nht hot ngng bo v th hai hot ng Knh bo hiu OMS 4 SPRing cho vng ring 4 si - hai hng.Vi trng hi ny mi chng c bn si quang, mi cp si quang dng truyn lu lng hot ng, mt cp si quang kia dnh cho d phng bo v chocplmvic(50%tngdunglngchobov). Khi xyrasccc chuyn mch bo v c thc hin bi cc chuyn mch 22 theo k thut quang c hay k thut khc.

xlivHnh 2.21 Ring bn si hai hng chuyn mch bo v on ghp knhSi bo vk i i i Si bo v Si bo v ng bo v th nht hot ngng bo v th hai hot ng Knh bo hiuKhi xy ra s c on th Ring c hi phc bng vic s dng chuyn mch bo v ti hai nt k cn vi on b s c ni vng lu lng trn cc si hot ng ln cc si bo v. Yu cu c bo hiu phi hp chuyn mch c hai nt kt cui on b s c.V d c phin truyn thng hai hng gia nt A v nt C khi xy ra s c on gia nt A v nt D nh hnh v 2.22 trong hnh a l trng hp iu kin bnh thng cn hnh b iu kin xy ra s c. Khi xy ra s c th xut hin knh bo hiu gia nt A v nt D sau hai nt ny thc hin chuyn mch bo v chuyn cc bc sng ln knh d phng.

2.4 Cc phng php bo v trong kin trc lin kt gia cc lp quang2.4.1 La chn cc kin trc mng tham chiu Trong thc t cc mng quang thng c xy dng theo kin trc phn cp, mi cp c th xem nh mt min mng con.Cc min mng con c trin khai thng s dng cc cu hnh c bn nh CS Ring, OMS Ring, v cu hnh li quang ca cc OXC.xlvk i i i i i k i k i i i OXC OXC OXC OXC Hnh 2.22 Ring bn si hai hng s c on OMS 4SPRingSi bo v Si bo vNt CNt A Nt D Nt A Nt DNt C Nt B Nt B ng bo v th nht hot ngng bo v th hai hot ng Knh bo hiuHnh a Hnh b CS Ring l mt kin trc thun li cho vic kt hp cc chc nng SDH ca cc thit b sn c trn mng (nh tuyn v bo v MS) vi chc nng nh tuyn quang ca cc nt logic. OMS SPRing l mt kin trc mng ton quang tin tin h tr thc thi c nh tuyn v bo v quang. Do kin trc ny rt quan trng i vi vic lp k hoch cho cc mng quang. Kin trc li quang ca cc OXC h tr nh tuyn v hi phc quang gip n gin ho s phc tp khi xy dng cc mng cu hnh li dung lng cao t cc thit b tng in.Da trn ba cu hnh c bn CS Ring, OMS SPRing, v cu hnh li quang ca cc OXC chng ta xy dng bn kin trc mng tham chiu sau: KintrcCSRinghai mc: hnh2.23thhinmt kintrcCS-Ring/CS hai mc.y l mt kin trc phn cp gm hai CS Ring lin kt vi nhau thng qua cc kt ni cho SDH.u im chnh ca kin trc ny l vic cp pht bc sng c th c lp k hoch cho mi Ring mt cch c lp. Kin trc OMS SPRing hai mc: hnh 2.24 th hin kin trc OMS-SPRing hai mc.xlvik i i i CS - Ring CS - Ring CS - Ring Hnh 2.23 Kin trc CS - Ring/CS - Ringi i k i k i i i OXC OXC OXC OXC k i i OXC i OXC OXC OXC OXC OXC OXC OXC u im chnh ca kin trc ny l kt ni quang gia cc Ring. Trong cc hub kh nng mm do mc knh quang ph thuc vo dung lng kt ni cho quang m cc OADM cung cp. Kin trc hai mc li/Ring: hnh 2.25 th hin kin trc li quang/ OMS-SPRing hai mc.y l mt kin trc c nhiu ha hn ng dng nht trong tng lai. Lu lng cc Ring lp di c tp hp v truyn ti bi lp bn trn c lu lng rt cao ging nh trong mng SDH truyn thng. Trong mt mng ln cc OXC c th c chc nng bin i bc sng nhm thit lp rt nhiu tuyn xlviii i k i OMS - SPRing Hnh 2.24 Kin trc OMS SPRing hai mcOMS - SPRing OMS - SPRing k i i i OMS - RingOMS - Ring Hnh 2.25 Kin trc li quang/OMS - SPRingOXC OXC OXC OXC k i i OXC i OXC OXC OXC OXC OXC OXC OXC quang. Phng thc bo v kt ni mng con (OSNCP) (bo v tuyn 1+1) c th l mt la chn cho kin trc ny. Kin trc hai mc Ring/li: hnh 2.26 th hin kin trc OMS-SPRing/ li quang hai mc.Trong mt s trng hp kin trc ny c th cung cp mt gii php ti u, khi ta s c mt Ring quang dung lng rt cao lin kt gia cc mng con c cu hnh li tng di.Vn bo v tng t kin trc hai mc li/ring.Bng 2.1 So snh mt s tham s ca bn kin trc mng tham kh.Cc tham s CS Ring hai mcOMS-SPRing hai mcOMS SPRing/ li quangLi quang/ OMS - SPRingKt ni SDH(VC-4/3/12)Quang(OC) b hn chQuang (OC) Quang(OC) (VC-4/3/12)Phc hi tng quangKhng C (hn ch) C (hn ch) CMm doSDH OXC Giihn Tt TtMc kt ni VC4 Bc sng Bc sng Bc sngMc Thp Tt Tt TtThit b Hub SDXC OADM OXC OXC(SDXC)Loi mng con Ring Ring Ring/OXC/Link Ring/OXC/Link xlviiiHnh 2.27 Lin kt dual homing da trn kin trc ring o, (a)p dng cho OC-DPRing, (b) p dng cho OMS - SPRingk i i OXC OMS - SPRing i Hnh 2.26 Kin trc OMS SPRing/li quang OXC OXC OXC OXC OXC OXC OXC 2.4.2 Lin kt gia cc mng con v vn bo vHot ng lin kt bo v gia cc min mng quang ph thuc vo chc nng v c tnh ca cc nt kp lin kt gia cc mng con. Nhm n gin ho ch phc tp ny ta ch tp trung vo phn tch kin trc mng vng ring hai si. Trong cc mng quang thc t, hai ring con thng lin kt vi nhau thnh mt ring kp thng qua hai nt OADM v to ln hai kin trc: kin trc ring o (VRA), kin trc tch v chuyn tip.2.4.2.1 Bo v vi kin trc ring o(VRA)Kintrcring o ban ucthch cngdngchoOC -DPRing. Phng thc nh tuyn v bo v c ch ra trn hnh 2.27a s dng cc nt lin kt chuyn tip vin (border) gia cc vng ring ti cng bc sng.ivi OMS-SPRingnhch ratrnhnh2.27bcnthit lpccbc sng t A ti B, v nh tuyn cc bc sng theo mt tuyn ng tch bit. Trong thc t hot ng bo v tng OMS c kt hp vi phn tp tuyn tng OCh.Cc phng thc bo v c p dng phc hi mt s c nt hoc on lin kt xy ra trong mi ring, cn chin lc phn tp tuyn c dng phc hi kt ni i vi s c on lin kt gia hai ring. Tuy vy nu cc bc sng nycng mang cc kt ni tng client nh nhau th gii php ny s ti hn gii php ng dng VRA trn cc OC - DPRing, v n yu cu bng thng gp i m khng tng c kh dng. Ni chung khi ng dng phn tp tuyn tnh th mi tuyn gia mt cp nt ch mang mt na cc kt ni tng client gia hai nt , dn n hai h qu: S lng bc sng mang trn tng quang theo nguyn l ch c mt na nu khng th s khng cung cp c ti nguyn d phng mc d iu ny c th cng lm gim thm mc s dng thp ca cc knh quang khi lng nhu cu tng client khng ln. Kh nng phc hi nhanh cc kt ni client chng li cc s c c thc thi ti mt trong hai tng gn s c hn.xlixHnh 2.27 Lin kt dual homing da trn kin trc ring o, (a)p dng cho OC-DPRing, (b) p dng cho OMS - SPRingTrn thc t trong nhng trng hp ny kin trc hnh 2.27b s truyn mt na s kt ni ca tng client gia hai nt A, B trn bc sng 1v mt na cn li trn bc sng2. Do n c th: Phc hi tt c cc kt ni client khi xy ra mt s c nt n hoc s c on n trong mi ring. Ch phc hi mt na cc kt ni client khi xy ra mt s c on lin kt.iu ny gip tng cng hiu qu s dng ti nguyn nh khi s dng VRA trn OCh-DPRing nhng li gim kh nng phc hi nhanh lin kt. Do phngthctronghnh2.27bkhngthcxemnhmt linkt dual-homing.2.4.2.2 Cc kin trc ring o ci tinC mt s kin trc khc c th tng cng hiu nng ca VRA trn OCh - DPRing m khng nht thit phi s dng chc nng tch v chuyn tip quang l gii php s dng mt single - homing trn cc ring lin kt vt l vi nhau lL1 L2L3L4Nt ANt BL1 L2L3L4Nt ANt BHnh aHnh bHnh 2.27 Lin kt dual homing da trn kin trc ring o, (a)p dng cho OC-DPRing, (b) p dng cho OMS - SPRingqua cc nt kp. Hnh 2.28 miu t kin trc ny trong cc trng hp OCh - DPRing v OMS - SPRing.Lin kt logic l mt single-homing v mi bc sng c tch t ring bi duy nht mt OADM.Mc ch y l s dng mi bc sng truyn mt na s kt ni tng client nn v mt nguyn l th yu cu ti nguyn ging nh trng hp ca VRA trn OCh DPRing (hoc tt hn tng ng vi OMS-SPRing). Mi mng con (SSN v d mt ring) khng ch phc hi mt s c nt n hoc s c on n, m c th cho php chng li c trng hp nhiu xy ra s c (mi s c trn mt ring) gia nt A v B. Nhng c hai kin trc ny u km hn kin trc s dng VRA trn OCh - DPRing ti cc nt lin kt: ch phc hi mt na s kt ni tng client khi xy ra s c ti v tr lin kt. Nu thc thi bo v cc b 1:N cc knh quang lin kt gia L1 v L3,gia L2 v L4 vt qua im yu ny th gii php ny cng kh hiu qu v mt chi ph.liL1 L2L3L4Nt ANt BL1L2L3L4Nt ANt BHnh aHnh bHnh 2.28 Kin trc ring o ci tin, (a)OC-DPRing, (b) OMS - SPRingNhn ton cnh mt mng quang ta c th thy n c cu thnh t mt mngli (mngtrcbackbone)vccmngconthnhphnlinkt vi mng li mng li v lin kt vi nhau. Cc kch bn bo v trong cc mng WDM c phn tch trong cc cu trc t p c bn nh ng thng, vng ring, li (mesh). Hai cu hnh vng ring v mesh hin ang thu ht c s quan tm ch yu ca cc nh thit k. Sau nghin cu hot ng ny khi lin kt gia cc mng con vi nhau, v khi lin kt vi cc tng khc bn trn (nh SDH, ATM,IP) .i vi cu hnh ng thng ta c th p dng trc tip cc k thut bo v tuyn ring/chia s. Mc d c bo v nhng cu hnh ny tim tng rt nhiu nguy c nh t c tuyn cp hay s c thit b nn n ch c s dng giai on u th nghim cha pht trin dung lng m khng my khi c s dng trong cc mng qui m ln. Cc phng thc bo v 1+1/1:1 SONET/SDH. im khc bit gia bo v WDM v SDH l khi ch khi xut hin s c trn mt si hot ng th chuyn mch ca u thu tng ng ca pha pht khng bit g. Trong khi SDH c hai u thu u bit trng thi ca si bo v.Cc kin trc OCh DPRing v OCh SPRing thc thi bo v lp knh quang. Cc kin trc OMS DPRing v OMS SPRing thc thi bo v lp on ghp knh quang nn tt c cc knh quang trn cng mt chng s c bo v ng thi khi xut hin s c.OCh DPRing s dng cc chuyn mch quang chuyn mch lu lng ln si bo v khi xy ra s c v khng yu cu bo hiu. Cu hnh ny c th chng li s c chng n, s c a chng,hay s c ti nt trung gian trn tuyn hot ng nhng c nhc im chung l yu cu chi ph t hn so vi cc gii php khc. Trng hp OC DPRing bn si nu cho php ti s dng cc bc sng th tng s bc sng s gim xung nhng yu cu chuyn mch bo v c hai u cui trnh xung t bc sng trn si bo v khi xy ra s c.OCh DPRing s dng hai si truyn ti lu lng theo c hai hng. Trong iu kin bnh thng, mi si mang mt bc sng khc nhau (1 thun liichiu kim ng h, 2 ngc chiu kim ng h). Nu mt on hay mt nt b s c th cc nt k cn s nh tuyn li cc bc sng cho on cung b ca n.Cu hnh OMS SPRing phi thitk bo v ring cho tng chn nn rt t v khng c tnh kh thi. Cu hnh OMS SPRing bo v chia s nn cho php s dng ti nguyn kh hiu qu. OMS 2 SPRing truyn lu lng trn c hai si, mi si cp pht mt na tng s cc bc sng cho cc knh hot ng, na cn li d phng bo v cc knh hot ng trn si kia.Nu mt on hay mt nt b s c, cc nt k cn s dng cc chuyn mch 22 nh tuyn li cc knh hot ng truyn qua on cung ln cc knh bo v ca si truyn ngc hng ti cng mt bc sng hot ng.OMS 4 SPRing l ring WDM hai hng mi chng c bn si quang, mt cp si quang dng truyn lu lng hot ng, mt cp si quang kia dnh cho d phng bo v cho cp hot ng. Khi xy ra s c s dng cc chuyn mch nhanh 22 ti hai nt k cn vi s c chuyn mch bo v ni vng lu lng trn cc si hot ng ln cc si bo v. Yu cu c bo hiu phi hp chuyn mch c hai nt kt cui s c.C hai gii php bo v 1+1 v 1:1 u dnh ti 50% dung lng cho bo v v c th p dng bo v tng knh quang trong mng li WDM, cc OXC chuyn tip khng phi cu hnh li trong trng hp xy ra s c. C ch bo v ring c th phn chia thnh hai loi: mt l loi tuyn bo v v tuyn hot ng ch tch bit v SRG, hai l tuyn bo v v tuyn hot ng tch bit c v SRG v cc nt trung gian.Trong bo v chia s tuyn, mt tuyn quang bo v gia hai nt c thit lp bo v cho N tuyn quang hot ng gia hai nt. Bc sng d phng dnh ring trn cc on ca ng d phng c th chia s vi cc ng d phng khc. Gii php ny gim c chi ph nhng phc tp hn v cch thc thc hin do yu cu trao i thng tin bo hiu v phi cu hnh li cc OXC kt cui cc knh WDM chia s.i vi cu trc mng quang WDM hnh li (mesh) s dng cc OXC chuyn mch quang trn ton mng. C nhiu cch thc thi bo v on trong cu hnh mesh,nhng trn thc t c hai chin lc cp pht dung lng d liiiphng ph bin: gii php s dng cc vng ring vu hi v gii php tng qut ho vng lp ngc.Nguyn l cc vng ring vu hi p dng cho mng li WDM nh sau: trc ht mng c phn tch thnh mt s nhm con cc si, mi nhm con c qun l nh mt vng ring v c trang b mt h thng bo v OMS ging nh OMS SPRing. Khi mi h thng bo v s phn ng vi s c bng cch ni vng cc kt ni b s c. Mt s gii php ang c nghin cu v hon thin trn th gii: gii php ph nt. gii php ph vng, gii php ph vng kp v gii php P cycle.Trong thc t cc mng quang thng c xy dng theo kin trc phn cp, mi cp c th xem nh mt mng con. Cc min mng con c trin khai thng s dng cc kin trc c bn nh CS Ring, OMS SPRing, v kin trc li s dng cc OXC. Da trn ba kin trc c bn ny,ta c th to ra bn kin trc mng tham chiu l: CS Ring hai mc, OMS SPRing hai mc, kin trc li/ring, v kin trc ring/li.livCHNG IIIPHC HI MNG V PHN B LI TI NGUYN3.1 Cc khi nim3.1.1 Phc hiPhc hi l mt phng thc s dng cc ti nguyn d phng kh dng nh tuyn li lu lng sau khi xy ra s c, theo tnh trng khi ca mng. chng II ta ni ti vn bo v. im phn bit gia hai phng thc bo v v phc hi l: cc k thut bo v da trn cc kch bn xc nh tuyn /on bo v cho mi tuyn /on hot ng cn bo v trc khi xy ra s c, cn cc k thut phc hi s dng cc thut ton nh tuyn tm mt tuyn /on d phng kh dng thay th tm thi cho tuyn /on hot ng b nh hng sau khi xy ra s c. Do cc k thut bo v thng p ng thi gian hi phc nhanh hn cc k thut phc hi ng nhng b li cc k thut phc hi cho php s dng cc ti nguyn d phng mm do hn.Nh ta bit mi trng WDM c chia thanh 3 lp; lp knh quang (OCh-Optical Channel), lponghpknhquang(OMS- Optical Multiplex Section) v lp on truyn dn quang (OTS Optical Transmisstion Section). Tng ng vi mi lp ta c cc cch phc hi ring bit. Phng thc phc hi knh quang: phng thc ny yu cu thay th mi tuyn quang hot ng b nh hng bi s c bng mt tuyn quang bo v. Vic tm tuyn bo v c th c thc thi bng iu khin phn tn hoc tp trung. Trng hp p dng iu khin tp trung, mt nt iu khin lu gi bn ghi trng thi ca mng v tm cc tuyn bo v ri thng bo cho cc nt mng. Trng hp p dng iu khin phn tn, c nt ngung v ch s r sot ng cc bc sng bo v c yu cu thit lp li tuyn ng b t. Phng thc phc hi on ghp knh quang: phng thc ny yu cu tm kim cc b mt tuyn tm thi kh dng vng qua on b s c. Phng thc ny c thc thi ti cc nt u cui on b s c, s dng mt thut ton phn b tm tuyn thay th tm thi.lvimphnbit giaphchi knhquangvphchi onghpknh quang l mc bo v hay n v bo v. Trng hp th nht ly i tng bo v l tuyn quang nn bo v knh quang c gi l bo v tuyn, n cho php la chn hi phc cc s c kt cui ng dy quang (OLT). Trng hp th hai ly i tng bo v mc tn hiu tng l tn hiu ghp knh ca cc knh WDM truyn trn mi si quang nn bo v on ghp knh cn c gi l bo v on, n s hi phc tt c cc tuyn quang hin c mang trn on si b s c.Cc k thut phc hi quang c th c thc thi mc knh quang p dng cho cu hnh li vi cc nt OXC. Hin nay trn th trng cha cung cp cc thit b OXC c hiu nng cao nhng mt s nh sn xut ang pht trin cc thit b kt ni cho quang - in c thit k c bit cho phc hi phn tn nhanh.Trongmt hthngmngvinthngcthxyraccscnh; t ng truyn gia hai nt mng; s c ti nt mng. T cc s c ny ta c ba phng php phc hi mng: phc hi t u cui - ti - u cui ca tuyn hot ng, phc hi ti cc nt k cn vi s c, v phc hi ti nt trung gian.3.1.1.1 Phc hi u cui - ti - u cui lviHnh 3.1 M t phc hi u cui-ti-u cui i vi s c on lin ktng kt ni gia hai ntTuyn hot ng trc khixy ra s cTuyn hot ng sau khi xy ra s cKhi xy ra s c th phng php phc hi ny s thc hin nh tuyn li t cc nt u cui ca cc knh b nh hng bi s c. Phng php phc hi ny m bo hiu qu nh nhau i vi c s c nt v s c on lin kt3.1.1.2 Phc hi ti nt k cn s cKhi xy ra s c th phng php phc hi ny s thc hin nh tuyn li cho cc knh i trn on ni gia hai nt k cn vi s c on, phng php phc hi ny khng hi phc c lu lng trong trng hp s c nt 3.1.1.3Phc hi ti nt trung gianlviiHnh 3.2 M t phc hi u cui-ti-u cui i vi s c ntng kt ni gia hai ntTuyn hot ng trc khixy ra s cTuyn hot ng sau khi xy ra s cHnh 3.3 M t phc hi ti nt k cnng kt ni gia haintTuyn hot ng trc khixy ra s cTuyn hot ng sau khi xy ra s cKhi xy ra s c th phng php phc hi ny s thc hin nh tuyn li cc knh b nh hng bi mt s c gi bt k cp nt trung gian no. Phng php phc hi ny s dng dung lng d phng rt hiu qu v n cho php nhtuynli kt ni mt cchti umkhngcccrngbucnhhai phng php trn, nhng yu cu thut ton phc tp hn. Trong cc phng php phc hi trn th phng php phc hi ti cc nt bin thng cho p ng tuyn phc hi di hn so vi phng php phc hi ti nt k cn s c. Tuy vy phng php th hai li yu cu phi tp trung nhiu dung lng d phng gn cc v tr d gp s c dn n tng dung lng d phng m n yu cu cao hn trong khi phng php u c th lp k hoch dung lng d phng va hi phc cc s c n ph hp vi qui m mng.V kh nng khc phc s c th tt c cc phng php phc hi u p dng c cho mt s c chng. Ring phng php phc hi ti nt k cn s c khng c kh nng i ph vi s c nt.V thi gian hi phc th phng php phc hi ti nt k cn s c c th s dng mc on ghp knh quang (OMS), lin ti it nt hn v thng cho tuyn ng phc hi ngn hn nn p ng hi phc nhanh hn.Di y l bng so snh cc phng php phc hilviiiTuyn quang trc khi xy ra s cTuyn quang sau khi xy ra s cHnh 3.4 M t phc hi ti nt trung gian i vi s c onng kt ni gia hai ntTuyn hot ng trc khixy ra s cTuyn hot ng sau khi xy ra s cPhng php phc hi Nt k cn s c Nt binDung lng d phng yu cu Nhiu hn t hnKh nng khc phc s c Ti hn Tt hnThi gian hi phc Ngn hn Di hn Bng 3.1 So snh cc phng php phc hi3.1.2 Cp pht ti nguynPhn b li ti nguyn l mt vn cn thit trong xy dng, vn hanh v khai thc mng, c bit l khi khi phc s c. i vi cc mng quang, c bit l mng quang WDM th phn b li ti nguyn l rt quan trng. N gm cp pht si quang, bc sng, thit b WDM v thit b u cui. T kt qu x l s c tnh sc s lng bc sng v cc thnh phn mng cn b sung.Hot ng cp pht mt kt ni knh quang cho cc cp v cc si quang khng c g mi l i vi cc nh lp k hoch xy dng mng SDH trc y, nhng vic gn mt bc sng cho mt knh quang, nh tuyn cc bc sng quang l mt nhin v mi kh phc tp. Nu mng c h tr bin i bc sng (s dng cc b pht p hay b bin i bc sng) th vn ny c gii quyt n gin nhng li lm tng chi ph xy dng nt mng. Do khi cp pht ti nguyn cho cc mng WDM c hai kha cnh cn phi xem xt Mt l cc h thng WDM thng c thit k vi s lng bc sng xc nh hu hn. Hail vn xung t bc sng c th xy ra nu cc knh quang khc nhau hot ng cng bc sng trn cng mt si.V hai vn ny m cc nh thit k phi ti thiu ho s lng bc sng s dng khng vt qu dung lng ca h thng WDM v trnh c xung t bc sng.Khi xem xt vn cp pht bc sng cn bit r mng c h tr bin i bc sng hay khng, t c ba trng hp cp pht bc sng: Cp pht tuyn bc sng o ( Virtual Wavelength Path - VWP): bc sng c cp pht c th thay th trn tuyn ng ti nt ch. Trng hp ny tng t nh hot ng cp pht ti nguyn trong cc mng SDHlix Cp pht tuyn bc sng (Wavelength Path - WP): ch cp pht mt bc sng duy nht dc theo tuyn ng t nt ngun ti nt ch. Trng hp ny dn n nguy c xung t bc sng gia hai tuyn chia s cng mt si quang. Cppht tuynbcsngnghm(TuneableWavelengthPath- TWP): cp pht c nh hai bc sng khc nhau cho cc tuyn hot ng v hi phc. Phng php ny l phng php trung gian ca ca hai phng php trc.Khi xem xt v c im lu lng ti trn mng (ti tnh hay ti ng ) chng ta c hai cch thc cp pht ti nguyn tng ng: Cp pht ti nguyn vi lu lng ti tnh: c th c thc hin mt ln hoc theo k hoch nhiu chu k (lu lng ti d bo kh chnh xc cc thi im). Trong c hai trng hp lu lng u c khuynh hng tng ln v c th p dng cc cng c ti u d bo s tng trng ny. Cp pht ti nguyn vi lu lng ti ng (trong trng hp lu lng ti bt nh): lu lng d bo ch c th thng k, v d cng lu lng ti a c mong i hay mc tp trung lu lng trong mt ring. Ngi thit k phi lm sao p ng c mc mm do ca mng cao nht vi chi ph thp nht. 3.1.3 Cc phng thc thc thi cp pht ti nguyn S dng cc thut ton ti u: cch ny c th rt chm nhng thch hp vi cc mng ln, lu lng tnh v ni chung cn d bo lu lng chnh xc. Chng c th c dng nghin cu so snh cc kiu mng khc nhau, phn tch mc nhy cm a ra nhng kt qu c gi tr. S dng cc lut thit lp k hoch n gin: cch ny c th thch ng ngay cho thc thi v vn hnh cc mng thc t (v d khi ci t dung lng mi cn nh tuyn cho cc nhu cu mi).3.1.4 Cp pht ti nguyn trong cc k thut bo v mngTrong mng thng tin quang WDM vn cp pht ti nguyn cho mc ch bo v lu lng v hi phc mng sau khi xy ra s c rt quang trng, c lx ngha quyt nh n vic lp d n xy dng mng quang, d tnh chi ph v xc nh cu hnh mng kh thi.Hin ti c ba trng hp cp pht ti nguyn sau. Chng c phn bit da trn s lng bc sng yu cu b sung cho mc ch bo v. 3.1.4.1 Bo v trn chnh bc sng ca thc th c bo v (khi ch c cc nt WR) Phntpsi quang: bngcchtnggpi ti nguyncnthit truyn ti lu lng mng. Cch bo v 1+1 ny m bo hi phc 100% cc s c tuyn nhng khng m bo hi phc cc s c nt. Phn tp ng nh tuyn: i vi mi ng nh tuyn s dnh mt ng nh tuyn khc cho mc ch bo v, ti u ho v mt ti nguyn mng th vic xc nh hai ng khc nhau vi cng bc sng cho mi cp nt phi c thc hin trong pha cp pht ti nguyn bo v. Cch ny c th bo v mng chng li cc s c trn on, tuyn v ti cc nt trung gian. Bo v da trn ring: xc nh cc vng ring t bo v trn mng cu hnh li. Cch ny cho php s dng cc k thut bo v chia s ging nh bo v ring SDH. Lp k hoch cc ring i qua cc nt trong mng vi cc yu t rng buc (nh tr, s lng cc nt, v chiu di tuyn...) 3.1.4.2Bo v trn cc bc sng khc nhau (trng hp c sn cc nt WC)Vi cch ny cho php dng cc k thut bo v ring hay chia s, v ti u ho ton b ti nguyn mng theo cch: ban u dng cc WL cha b chim dng sau thc hin phn tp si quang. iu ny c thc hin trong pha lp k hoch cp pht ti nguyn mng. Nu mun cung cp bo v trn c si quang khi b t th knh bo v khng nn trn cng mt si quang vi knh c bo v.3.1.4.3Bo v trn cc tuyn a bc sng (trng hp cc nt WR kh dng) Hnh thc ny dng ti u ho ton b ti nguyn mng khi khng c s hn ch v WL trn tuyn. Ban u s dng cc bc sng cha b chim dng sau mi p dng phn tp si quang. Cng vic ny c th thc hin trong pha lp k hoch cp pht ti nguyn mng. Tng t trng hp trn trnh lxinh hng khi b t cp knh bo v khng nn chia s cng mt si quang vi knh c bo v.3.2 Phn b lu lng trong qu trnh hi phc mngu tin chng ta nghin cu v vn cp pht ti nguyn vi lu lng ti tnh trong cc cu hnh ring, li, sau l vn cp pht ti nguyn vi lu lng ti ng trong cu hnh ring. Trong cc trng hp nghin cu, lu lng gi thit l cc khi. Mt khi l mt yu cu truyn ti thng tin gia hai nt mng quang trn mt bc sng. Khi quang c th c nh tuyn t u cui - ti - u cui trn mt bc sng sut tuyn ng i hoc trn cc bc sng khc nhau nu s dng bc sng. 3.2.1nhtuynlulngvcpphtti nguynchoccmngquang WDMvi lu lng tnhPhn ny trnh by v cp pht ti nguyn bc sng cho cc mng WDM cuhnhringclulng tnh thoba nhmsau:nhm ring WDM bo v ring, nhm ring WDM bo v chia s v nhm ring WDM khng bo v.Cc ring WDM bo v ring n hng hoc hai hng c cc knh quang hot ng c bo v i ph vi s c t cp bi cc knh bo v dnh ring truyn hng i din ca ring. Do cc knh hot ng v bo v c th cng chia s mt bc sng cc hng truyn dn khc nhau trn ring nn vn cp pht ti nguyn rt n gin, ta c th cp pht mt bc sng cho mi nhu cu khi. V d trng hp mt ring WDM vi N nt c N*(N-1)/2 khi th s lng bc sng yu cu trn ring WDM hai si bo v ring l N*(N-1)/2. Tng t vi ring WDM n hng khng bo v, c hai hng truyn dn cho mi khi s dng mt bc sng trn tt c cc tuyn vng quanh ring.Cc ring WDM bo v chia s (thng l ring hai hng, i khi cng p dng nh tuyn n hng cho mt s khi): khi cp t ti mt cung n vn cdunglngdphngtrnphncngbhi phcchonhngkhi quang b t kt ni (v d OMS - SPRing).CcringWDMhai hngkhngbov: nhimvbovcthc chuyn ln cc tng khch s dng dung lng trn chnh ring hoc trn cc lxiiphn khc ca mng nhng khng cn dnh ring bt k bc sng no cho mc ch bo v.Cc ring ny cho php ti s dng bc sng truyn cc khi quang khc nhau nn v l thuyn chng yu cu t bc sng hn. Nhng b li cc khi quang phi c nh tuyn chnh xc v c cp pht cc bc sng sao cho m bo kh nng ti s dng ti a. Nu cc nt c h tr bin i bc sng th vn tr nn n gin: nhng nu cc nt s dng b ghp knh xen/r th ng th khng c kh nng bin i bc sng cho cc knh lu lng truyn qua, do mi nhu cu quang phi c cp pht mt bc sng t u cui - ti - u cui khin cho cng vic ny tr ln phc tp. Khi phi tm ra mt phng thc cp pht bc sng ti u m ch c s dng mt s lng bc sng hn ch nh trong trng hp c h tr bin i bc sng. V d trng hp ring WDM hai si bo v chia s c N nt, ta ch c yu cu [(N2 1)/4] bc sng, khi s N ln gi tr ny gn bng 50% so vi trng hp bo v rin. i vi ring bn si bo v chia s hoc ring WDM hai hng khng bo v th s lng bc sng yu cu l [(N2 - 1)/8] m yu cu h tr bin i bc sng th khng thch hp.Nhn chung nhu cu lu lng him khi t ti mc ti a nhng v lu di cn thit phi tm ra cc cng thc chung hoc cc lut cp pht bc sng n gin. ti thiu ho vic s dng cc bc sng rt cn cc thut ton cho p ng nhanh.Trong thc t p dng mt lut cp pht ti nguyn kh tt theohai giai on lin tip sau. Giai onmt (giai onnhtuyn): nhtuyncckhi quang truyn cng chiu hoc ngc chiu kim ng h nhm ti thiu ho tng s bc sng s dng trn mi on (vi gi thit c h tr bin i bc sng). Cc nhu cu quang (cc khi) c cp nhiu bc sng c th c tch ra, v mi bc sng c nh tuyn ring nu yu cu. Sau s dng mt thut ton p ng nhanh sn c nh tuyn ti u nhm t c s lng cc bc sng trn mi on l t nht c th. Giai on hai: giai on cp pht bc sng cho cc tuyn c xc nh khi kt thc giai on mt: ta c th s dng cc thut ton Stochastic hay lxiiicc thut ton phong on nhm t c hiu qu phn b tt c cc bc sng nh mong mun .Giai on u nhm to ra mt mc ngng s lng cc bc sng yu cu thp hn m cha xt ti vic khng c h tr bin i bc sng.Giai on hai thc thi cp pht bc sng theo gii hn 3.2.2nhtuynlulngvcpphttinguynchoccmngquang WDM vi lu lng ti ngTrong nhiu ng dng mng thc t khng phi lc no cng d on c trc cc mu lu lng, cc nhu cu quang (cc kh) c th tng hoc gim bt k nn cn thit phi xem xt cc mu lu lng ng xc nh mc linh hot v hiu qu ca cc mng WDM. Cc thut ton phi thc thi nh tuyn v cp pht cc bc sng trong iu kin lu lng ng nn cn m bo cc yu cu sau: m bo mc s dng mng cao m bit nhu cu lu lng ban u. Thut ton vn t hiu nng tt ngay c khi lu lng c s bin ng ln Thut ton n gin c th d dng lin kt gia cc mng con ca h thng qun l mng. Phn ny ta s xem xt lu lng ng trong cc mng ring WDM bo v chia s vi kch bn nh sau.Mt ring kt ni N nt, ban u cha c nhu cu quang (khi) no c nh tuyn Cc nhu cu quang xut hin ln lt v yu cu c phc v ngay lp tc. Cc yu cu ny xut hin ngu nhin vi xc sut nh nhau gia cc nt trn ring, nn phi tnh ton da trn trung bnh mu lu lng ton phn.Khi c mt nhu cu quang yu cu phc v phi tm thy ngay mt bc sng kh dng. Hiu nng ti xp xut cc bc sng cp pht cho lu lng trn ring phi m bo mc s dng mng cao hn, nhng vi k thut ring WDM hin nay yu cu xem xt c kh nng can thip nhn cng v t knh dch v khch hng do khng cho php tai sp xp.lxivNu c hin tng dao ng lu lng c th loi bt cc nhu cu quang (trn cc phn ring s dng) v bc sng cp pht cho nhu cu quang b lai str thnh kh dng i vi cc nhu cu quang mi c th c ng tuyn trn phn ring .C mt s lut cp pht ti nguyn lin quan ti hot ng nh tuyn v cppht bcsng: thut tontmngngnnht (SP), thut tontms lng bc sng it nht. so snh ta xem xt cc ring WDM c h tr bin i bc sng lun nhm nh tuyn cc nhu cu quang ln tuyn ngn nht. Cc nhu cu quang c to ra ngu nhin v cp cho ring WDM s dng lut chn cho ti khi tt c cc bc sng c s dng. Khi xy ra hin tng tc nghnth phi tnh ton li cc nhu cu c phc v thnh cng. thy c mc cp pht ti nguyn ti u t c ta s dng mt s cng c cp pht ti nguyn tnh th thc hin trn cng cc khi quang , nu thc thi tt hn th c th c nhiu bc sng kh dng hn.Vn dao ng ti ng c nh hng xu ti mng ring WDM nh hin tng phn mnh trong cng ca my tnh. Trong hin tng phn mnh ca my tnh th n xy ra do ta to ri li xo cc tp tin, cn vn dao ng ti th do cc nhu cu quang b loi ngu nhin khi ring WDM li mt khng gian bc sng b phn mnh, dung lng tha c phn b vng quanh ring trn cc bc sng khc nau nhng li khng c mt bc sng no hon ton kh dng ht mt vng ring.Cc ti nguyn kh dng phn tn ny li c dng cp pht cho cc nhu cu mi cn c nh tuyn qua mt s nt m khng c h tr bin i bc sng nn tt kho khn. Ngc li nu h tr bin i bc sng ta c th d dng tn dng dung lng tha trn mt vi bc sng nh tuyn cho mt nhu cu quang. Mt kt lun quan trng l nu mng ring WDM c dao ng ti cao, bo v chia s c th t kt qu s dng thp. Ngc li cc ring WDM bo v ring s dng cc lut n gin hn khng nhy cm vi cc dao ng ti: u im ca bo v chia s so vi bo v ring v mt yu cu bc sng c th b p nhc im mc s dng. thc thi thit k mng t c hiu qu cao ta cn nh c mng tho cc mu lu lng d bo thch hp, ly chi ph lm i tng tnh ton mc lxvkh dng v kim tra kh nng linh hotca mng. iu ny da trn lu lng tnh s dng mt s cng c ti u. V d: nh c OMS SPRing s dng chin lc nh tuyn v cp pht bc sng theo hai bc. Chng ta ta bit OMS SPRing c nhiu u im v yu cu di thng tt hn cc ring WDM bo v ring cng ging nh trng hp SDH SPRing tt hn SNCP ring. Kh nng h tr bin i bc sng khngthch hp lm ngoi tr trng hp lu lng ng khng c d bo trc, c bit khi c dao ng ti cao.i vi cc mng li WDM, thc hi tch bit cc tc v nh tuyn v cp pht bc sng l n gin nht. C th s dng thut ton tm ng ngn nht cho nh tuyn, mt thut ton heuristic hay cc cng c da trn SA v ILP cho cp pht ti nguyn.i vi lu lng ng ta nn chn cc mng ring WDM bo v chia s l thch hp hn c. Nu khng th d bo trc c lu lng,v hot ng nh tuyn khng th ti sp xp ng m khng xt n QoS th nn s dng lut SP s t c hiu qu s dng t 90% ti 95% (khi khng c dao ng ti), vgimxung70%(khi cgiaongti). iunykhinchoccring WDM bo v chia s km hm dn hn cc ring WDM bo v ring 1+1 s dng cc lut n gin hn nhiu. 3.2.3 Phng php nh tuyn trong mngWDM cu trc RingTng t trong mng cu Ring SDH, khi xet v tnh hiu qu s dng bng tn quang, hin nay cc cu trc ring ton quang c th chia thnh hai loi ch yu: RingbovdngchungSPRing(OMS-SPRing-Optical Multiplex Section Shared Protection Ring), tng ng vi cng ngh SDH c MS- SPRing hay ring hai hng. Ring bov dnh ring DPRing (OCH/OMS DPRing Dedicated ProtectionRinghayOCH-SNCPRingSub-NetworkConnectionProtection Ring) tng ng vi cng ngh SDH l loi SNCP Ring hay Ring n hng USHR.Trong loi ring bo v dnh ring DPRing (1+1) ti lp quang, lung tn hiu quang c gi i theo c hai hng ca vng ring bo v. Nguyn tc c bn phn b bc sng l: mi mt lung quang im - im s s dng lxvimt bc sng ring trn ton ring. Mc phc tp trong thit k mng vi cutrcDPRingskhngnmphnquangmchyuphngiaodin quang v VC-4. V d, xc nh s xp xp logic cc nt tt nht (cu hnh lp SDH), hoc cch ghp cc VC-4 vo bc sng l cn thit.i vi ring bo v dng chung SPRing,yu cu nh c phc tp hn. Nh thit k phi quyt nh hng tuyn thun/ngc chiu kim ng h cho mi lu lng v s dng bc sng nht nh no . Do c ch bo v dng chungchophpsdngbcsngtrncclungquangkhngchngcho nhau, nn s khng c nguyn tc thit k n gin no. Hn na nhim v phn b cc VC-4 vo tng bc sng s lm cho bai ton phc tp hn trong vng ring c bo v dng chung. Phn ny s tp trung vo nh tuyn v phn b bc sng cho SPRing p ng yu cu lu lng lung quang xc nh, m khng cp n vn nhm, phn b cc lung VC-4 vo knh quang y l phn quyt nh ca lp mng trn v thng thuc nh khai thc khc, c lp vi nh khai thc mng quang.Trong vn phn b ti nguyn d phng ni chung l rt kh.Nhng trong trng hp cu hnh ring th vi loi DPRing mi mt knh OCh lm vic s yu cu knh bo v theo hng i din, v vi cu trc loi SPRing,th mt na phn bc sng trn mi chng c s dng cho knh bo v v na cn li s dng cho d phng.V nguyn tc khi c s c xy ra phn bc sng lm vic b s c s chuyn sang phn bo v hng ngc li, do cn c chuyn i bc sng. Tuy nhin c th trnh s dng chuyn i bc sng nh b tr hai hai phn bc sng dnh cho lm vic v d phng ca hai si b nhau.Ngoi ra, vn nh c cho mng DPRing hon ton phi c thng qua phng php tnh n gin, bi v mi lu lng quang s yu cu s dng mt bc sng trn mi chng ca ring (cho knh bo v v lm vic).V vy d dng nh tuyn v gn bc sng cho DPRing trong trng hp ma trn lu lng quang c bo v hon ton. Tuy nhin. DPRing c th ti cc lu lng quang khng c bo v; nhng lu lng ny s lm cho phc tp hn khi nh cccDPRing. i vi trnghpnybi tonli quayvgii bi ton SPRing. Do vy trong phn ny ch cn tp trung v vn nh c SPRing. lxvii1 nu aj P(i, 2j-1) = 0nu aj 1 nu aj P(i, 2j) = 0 nu aj3.2.3.1 nh tuyn trong mng ring nnh tuyn. Nhim v ca bc ny rt quan trng, n xc nh nh tuyn lu lng thun hoc ngc chiu kim ng h vi gi nh c b chuyn i bc sng. Bc ny c th gii cho cho kt qu gn hoc ti u bng thut ton ti di truyn (Genetic),Heuristic hoc s dng thut ton ti u, xc nh hng tuyn ca mi lung lu lng. C hai loi phng php ph bin c s dng nh tuyn lu lng cho SPRing, l: Cc phng php Heuristic.Heuristic thch nghi.Heuristic khng thich nghi. Cc phng php ti u.a) Cc phng php nh tuynRt nhiu nh nghin cu trc xut vi phng php nh tuyn ti u cho mng SPRing. tng ca cc phng php ny l ti thiu chi ph ring bng cch ti thiu ti trng trn chng c ti cao nht, trong ti l tng cc lu lng nh tuyn qua chng . Hu ht cc thut ton u phi gii quyt vn cn bng ti trng, l cc lung quang c sp xp trn ring sao cho s chnh lch v ti gia cc chng cng nh cng tt. Mt trong nhng thut ton c C.Y.Lee v S.G.Chang xut v ch rakt qulti uhocnhiunht llnhngitr ti umt nv (N=[LMAX/2]+1).* Bi tonXtvngringcn nt (ncnh/cung/chng).Cc ntc nhstheo chiu kim ng h v cnh gia nt I v i+1 gi l ai. Cnh gia nt n v l l an. Mi mt lu lng gia hai nt l i xng v hai hng. K hiu:d = (d1, d2, d3, dm) l vc t lu lng trong dj l tng s lung ca lu lng jPj+= {as, as+1, . . .at-2, at-1} l tp cc cnh m ti lu lng j gia nt s v t (t n) theo hng kim ng hlxviii1 nu aj P(i, 2j-1) = 0nu aj 1 nu aj P(i, 2j) = 0 nu ajPj = {as, as+1, . . .an, an-1, . . .at+1, at} l tp cc cnh m ti lu lng j gia nt s v t(t n) ngc chiu kim ng hP l ma trn n2m, trong :x) , ,..., , , , (2 2 1 1 + + +m mx x x x x x l vc t kt qu, trong :+jx l s lung ca lu lng j c nh tuyn theo chiu kim ng hjx l s lung ca lu lng j c nh tuyn ngc chiu kim ng h R l ma trn (n2m) lu lng ca cnh, trong + ix j i P j i R ) 1 2 , ( ) 1 2 , ( jx j i P j i R ) 2 , ( ) 2 , (y) ,..., , (2 1 ny y y l vc t ti vi iyl ti trn cnh ic xc nh liy=jj i R ) , (z(x) = maxi {iy} l ti ln nht trong cc cnh i ng vi kt qu xA ={ai/ yi z(x)-1} l tp cc cnh c ti cc i nh hn 1Bi ton cn bng ti c th c biu din nh sau:Ti thiu hm mc tiu z(x).Tho mn iu kin:

iP i jjP i jjy x xj j + ++} / { } / { vi n i ..., 2 , 1 j j jd x x + + vi m j ,..., 2 , 1 +jx,jx nguyn dng vi mi jlxix1 nu aj P(i, 2j-1) = 0nu aj 1 nu aj P(i, 2j) = 0 nu ajYYj >n >:=nh tuyn cc lu lng bt u t nt i; nh gi ti y=(y1, y2,,yn );Xc nh tp A; Xdrq: i quatt c cc cnh thuc AHm mc tiu z(x) nhn c t nh tuyn +jx v jxca mi lu lng j sao cho ti ln nht l ti thiu. Rng buc th nht ch ra l ti ca cnhiyl tng tt c cc lu lng nh tuyn qua cnh ai c hai hng (ngc /thun chiu kim ng h), rng buc th hai ch ra lu lng c nh tuyn c hai hng phi bng dj, cn rng buc th ba l vic tch lu lng theo 2 hng phi nguyn dng. gii bi ton ny Lee v Chang xut thut ton sau: Bc 1: khi tox := (d1,0,d2,0, . . .,dm,0);Tnh ton y, z(x),A;t i:=1; Bc 2: kim tra iu kin n i : nu sai th kt thcTo danh sch cc lu lng bt ngun t nt i v sp xp theo th t gim dn ca gi tr+jP, tc l lung lu lng c s cnh/chng gim dn.Gi lu lng j:=lu lng u tin trong danh sch ca nt i Bc 3: lp li vi bc ny vi iu kin +jP A(tc l xt cc lung jm c nh tuyn i qua tt c cc cnh c ti cc i).t { };'1]1

+ + +2) ( min, min :kjP ky x zj j jx x x t { };'1]1

+ + 2) ( min, min :kjP ky x zj j jx x x; (chia lung lu lng j sao cho mi hng c ti tng t nhau)Tnh ton li y, z(x), AChn lu lng j:=lu lng tip theo trong danh sch Bc bn: t i:=i+1 ri thc hin bc hai.Theo ng Chang v Lee ch ra, li gii l ti u hoc nhiu nht l ln hn ti u mt n v. Thut ton:lxxYYj >n >:=nh tuyn cc lu lng bt u t nt i; nh gi ti y=(y1, y2,,yn );Xc nh tp A; Xdrq: i quatt c cc cnh thuc Ab) Cc phng php nh tuyn HeuristicMc d bi ton nh tuyn trn SPRing hon ton c th gii bng mt trong cc thut ton ti u trn, tuy nhin mt s thut ton Heuristic cng c s dng. Cc thut ton ny c mt s c im: n gin hn loi ti u m vn cho kt qu ti u hoc gn ti u trong hu ht cc trng hp. D dng hn cho vic duy tr lin tc gia cc qu trnh lp qui hoch v thit lp lung trong khai thcCc phng php Heuristic c th c a thnh hai nhm, thch nghi v khng thch nghi.lxxiYYYBt uSp xp dsd theo th t tng ca s v d;j >n >:=nh tuyn cc lu lng bt u t nt i; nh gi ti y=(y1, y2,,yn );Xc nh tp A;Kt thc Kdrq: i quatt c cc cnh thuc A) ( ) (*x z x z