Ti liu tham kho

MC LCContentsMC LCiDANH MC HNH VivLI M UviTHUT NG VIT TTviiCHNG 1: TNG QUAN V CNG NGH CHUYN MCH NHN A GIAO THC MPLS V GMPLS11.1. GII THIU11.2. CNG NGH IP21.3. CNG NGH ATM21.4. CNG NGH MPLS41.4.1. Cc khi nim c bn MPLS61.4.2. Thnh phn c bn ca MPLS81.4.3. Cc giao thc s dng trong MPLS91.4.3.1. Giao thc LDP (Lable Distribution Protocol)91.4.3.2. Giao thc CR-LDP (Constrain-based routing LDP)141.4.3.3. Giao thc RSVP-TE ( RSVP Traffic Engineering)171.4.3.4. Giao thc BGP191.5. CNG NGH GMPLS211.5.1. Gii thiu211.5.2. Hot ng v nn tng ca MPLS221.5.3. Qu trnh pht trin MPLS n GMPLS221.5.4. B giao thc GMPLS231.5.5. Mc tiu v cc chc nng mt phng iu khin GMPLS251.5.6. Kin trc cc thnh phn ca mt phng iu khin GMPLS261.5.6.1. Yu cu ca mt phng iu khin261.5.6.2. Mng thng tin s liu h tr mt phng iu khin GMPLS261.5.7. Bo hiu trong GMPLS281.5.7.1. Cc chc nng c bn291.5.7.2. H tr phc hi301.5.7.3. H tr x l loi tr301.5.7.4. Phi hp bo hiu311.5.8. Cc li ch ca GMPLS321.5.9. Cc vn cn tn ti ca GMPLS321.6. TM TT CHNG 133CHNG 2: GII THIU BI TON NH TUYN V GN BC SNG TRONG MNG QUANG WDM342.1. GII THIU342.2. CC LOI BI TON RWA352.2.1. Thit lp lung quang tnh (SLE)352.2.2. Thit lp lung quang ng (DLE)352.3. CC PHNG PHP GII BI TON352.4. C S L THUYT362.4.1. Gii thiu l thuyt th362.4.2. Gii thut DIJKSTRA362.5. BI TON RWA TRONG THIT LP LUNG QUANG TNH (SLE)372.6. BI TON RWA TRONG THIT LP LUNG QUANG NG (DLE)382.6.1. Bi ton nh tuyn382.6.1.1. nh tuyn c nh382.6.1.2. nh tuyn thay th c nh392.6.1.3. nh tuyn thch nghi da trn thng tin tng th402.6.1.4. nh tuyn thch nghi da trn thng tin cc b432.6.2. Bi ton gn bc sng472.6.2.1. Thut ton gn bc sng theo th t bc sng472.6.2.2. Thut ton gn bc sng ngu nhin472.6.2.3. Thut ton gn bc sng da trn bc sng s dng nhiu nht v t nht482.6.3 Bo hiu v t trc ti nguyn482.6.3.1. t trc song song482.6.3.2. t trc theo chng492.7. TM TT CHNG 249

CHNG 3: PHNG PHP NH TUYN V GN BC SNG DA TRN K THUT GMPLS503.1. MPLS V MNG QUANG THNG MINH503.1.1. Tm bao qut rng ln ca MPLS503.1.2. Cc giao thc nh tuyn v phn phi nhn trong nn MPLS.503.1.3 Hng ti ngn xp giao thc n gin hn: IP/MPLS qua DWDM.513.1.4. Tng quan gia MPLS v mng quang513.1.5. Lin kt v qun l ba mt phng iu khin523.2. BI TON NH TUYN V GN BC SNG TRONG MNG QUANG T CHC TRN K THUT GMPLS.523.2.1. Tng quan v k thut GMPLS523.2.2. Thit lp v khi phc lung quang533.3. CC IU KIN RNG BUC TRONG NH TUYN QUANG.543.3.1. iu kin rng buc vt l.543.2.2. Cc rng buc bc sng553.3. KIN TRC GMPLS553.4. B NH TUYN GMPLS THC T: B NH TUYN HIKARI563.5. TM TT CHNG 357

CHNG 4: M PHNG NH TUYN V GN BC SNG TRONG MNG QUANG WDM DA TRN K THUT GMPLS594.1. TNG QUAN V NS2594.1.1. Gii thiu594.1.2. Kin trc ca NS-2594.1.3. S dng chng trnh NS-2614.2. M PHNG634.2.1. Cu trc Mng634.2.2. M phng vi NS2644.2.3. nh ngha QoS654.3. M PHNG V KT QU654.4. KT LUN V HNG M CA TI704.4.1. Kt lun704.4.2. Hn ch ca ti714.4.3. Hng m ca ti71

TI LIU THAM KHO72

Mc Lc

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DANH MC HNH VHnh 1.1: Dng nhn MPLS dng chung 7Hnh 1.2: Vng hot ng ca LDP 9Hnh 1.3: Trao i thng ip LDP 10Hnh 1.4: LDP header 11Hnh 1.5: Format thng ip LDP 11Hnh 1.6: Cc loi bn tin LDP 12Hnh 1.7: V du LDP ch iu khin c lp theo yu cu 14Hnh 1.8: Thit lp LSR vi CR-LDP 15Hnh 1.9: Tin trnh d tr ti nguyn 16 Hnh 1.10: Thit lp LSP vi RSVP-TE 19Hnh 1.11: Ni dung bn tin BGP update 20Hnh 1.12: Mt s cu trc GMPLS 23Hnh 1.13: Cc giao thc v cc giao thc m rng ca GMPLS 24Hnh 1.14: Ngn xp giao thc GMPLS 25Hnh 2.1: Mng DWDM nh tuyn bc sng 34Hnh 2.2: ng i ngn nht c nh 39Hnh 2.3: Tuyn chnh (nt lin) v tuyn thay th (nt chm) 40Hnh 2.4: nh tuyn thay th 44Hnh 2.5: Bi ton nh tuyn ng i ngn nht 46Hnh 2.6: Bi ton nh tuyn lch vi tc nghn t nht 46Hnh 3.1: Cu trc b nh tuyn Hikari vi TE a lp trn gim st lu lng IP 56Hnh 4.1: Lung cc s kin cho file Tcl chy trong NS 60Hnh 4.2: Ca s chng trnh khi chy NAM 61Hnh 4.3: Cu trc mng m phng 63Hnh 4.4: Hin thc ho m hnh trong NS-2 64Hnh 4.5: Qu trnh gi cc bn tin d ng 66Hnh 4.6: S0 gi thng tin ti D0 thng qua nt 5-6-9 66Hnh 4.7: Bng nh tuyn 67Hnh 4.8: D liu truyn khi thc hin m phng 68Hnh 4.9: Kt qu m phng nh tuyn rng buc GMPLS 68Hnh 4.10: Xut bng cho thy t l mt gi bng 0 69Mc lc hnh

Hnh 4.11: Hiu qu s dng bc sng trong mi ng truyn 70SVTH: Nguyn L Minh Lp: 06VTA1Trang iv

LI CM NTrong thi gian gn 5 nm hc ti Hc Vin, em cm thy rt vinh d v t ho khi ngi hc di mi trng ny. Mt mi trng c y c s vt cht hin i cng vi i ng Thy C gii, y nhit huyt l m c hc tp ca nhiu bn tr. Trong qu trnh thc hin n tt nghip ny, cho php em c gi li cm n su sc ti thy NGUYN XUN KHNH v LNG NGC NHN nhit tnh hng dn, gp em hon tt c n tt nghip ny.Ngoi ra em cng xin chn thnh cm n cc thy c gio trong Khoa in T II, Khoa Vin Thng II - Hc Vin Cng ngh Bu Chnh Vin Thng C S ti Tp.HCM ging dy v to mi trng tt cho em hc tp v nghin cu.Cui cng em xin chn thnh cm n gia nh v cc bn hc cng lp D06VTA1 nhng ngi lun st cnh bn ti trong sut qu trnh hc tp cng nh trong thi gian lm n tt nghip. TP. H Ch Minh, thng 1 nm 2011Sinh vin

Nguyn L Minh

Li cm n

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LI M U

H thng thng tin quang ra i cng vi nhng u im vt tri ca n v ang c p dng rng ri trn mng li thng tin ton cu. Hin nay, cc h thng thng tin quang truyn dn tt c cc tn hiu dch v bng hp, bng rng p ng yu cu ca mng s tch hp dch v ISDN. V th, h thng thng tin quang s l mi t ph v tc truyn dn v cu hnh linh hot cho cc dch v vin thng cp cao.i vi h thng thng tin quang, mi trng truyn dn chnh l si quang, n thc hin truyn nh sng mang tn hiu thng tin t pha pht ti pha thu. nh tuyn v gn bc sng tr thnh chc nng khng th thiu c trong mng quang WDM. Vn t ra l nh tuyn ng i cho nh sng v gn bc sng cho n trn mi tuyn nh th no t c mt mng ti u. Trong n ny, em xin trnh by v ti nh tuyn v gn bc sng trong mng quang WDM da trn k thut GMPLS. n c chia thnh bn chng:

CHNG 1: TNG QUAN V CNG NGH CHUYN MCH NHN A GIAO THC MPLS V GMPLS.

CHNG 2: GII THIU BI TON NH TUYN V GN BC SNG TRONG MNG QUANG WDM.

CHNG 3: PHNG PHP NH TUYN V GN BC SNG TRONG MNG QUANG WDM DA TRN K THUT GMPLS.

CHNG 4: M PHNG BI TON NH TUYN V GN BC SNG DA TRN K THUT GMPLS.

Do thi gian thc hin v kin thc c hn, nn n ch phn no kho st c mt s kt qu m phng nh trnh by chi tit chng 4. Cc hn ch cng nh hng m rng ca ti c cp phn cui ca n. Rt mong nhn c s ng gp qu bu t qu thy c. Xin chn thnh cm n.Li m u

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THUT NG VIT TT

ADMAdd-Drop MultIPlexerB ghp knh xen r

ARISAggregate Route-Based IPChuyn mch IP theo phng php tp hp tuyn

ASAutonomous SystemH thng t ng

ASEAmplified Spontaneous EmissionPht x t pht c khuych tn

ATMAsynchronous Tranfer ModePhng thc truyn ti khng ng b

BGPBoder Gateway ProtocolGiao thc nh tuyn cng min

CLNPConnectionless Network ProtocolGiao thc mng phi kt ni

CPUCentral Processor UnitB x l trung tm

CR-LDPConstraint-Based routing Label Distribution protocolGiao thc phn b nhn c nh tuyn da trn rng buc

CSRCell Siwtching RouterB nh tuyn chuyn mch t bo

DCNData Communication NetworkMng tuyn dn s liu

DLCIData Link Connection IdentifierNhn dng kt ni lp lin kt d liu

DLEDynamic Lightpath EstablishmentThit lp lung quang ng

DWDMDense Wavelength Division MultIPlexingGhp knh phn chia theo bc sng mt cao (40 hoc 80 trn mt si quang)

ERExplicit Routernh tuyn tng minh

ERBExplicit Router Information BaseC s thng tin ca nh tuyn

EROExplicit Router Objecti tng ca nh tuyn

FSCFiber Switch CapableKh nng chuyn mch quang

FECForwarding Equivalence ClassLp chuyn tip tuoeng ng

GMPLSGeneralized Multi Protocol Label SwitchingChuyn mch nhn a giao thc tng qut

IETFInternational Engineering Task ForceTi chc tiu chun k thut quc t cho internet

IGPInterior Gateway ProtocolGiao thc nh tuyn trong min

ILPInteger Linear ProgramQuy hoch tuyn tnh nguyn

IPInternet ProtocolGiao thc lin mng

ISCDInterface Switching Capability DescrIPtorB m t kh nng chuyn mch giao din

IS-ISIntermediate System to Intermediatet SystemGiao thc nh tuyn IS-IS

IS-IS-TEIntermediate System to Intermediate Traffic EngineeringGiao thc nh tuyn IS-IS c k thut lu lng

LDPLabel Distribution ProtocolGiao thc phn b nhn

LMPLink Management ProtocolGiao thc qun l knh

LSALink State AdvertisementBn tin qung b trng thi lin kt

LSCLambda Switch CapableKh nng chuyn mch bc sng

LSPLabel Switching Pathng chuyn mch nhn

LSRLabel Switching RouterB nh tuyn chuyn mch nhn

MPLSMulti Protocol Label SwitchingChuyn mch nhn a giao thc

NGNNext Generation NetworkMng th h sau

NPSubnet op class NP problems CompleteTp hp con ca lp cc bi ton NP m n c xem rt kho gii

NHLFENext Hop Label Forwarding Entry

NHRPNext Hop Label Protocol

NLRINetwork Layer Rechability Information

NMSNetwork management SystemH thng qun l mng

OSPFOpen Shortest path FirstGiao thc nh tuyn OSPF

OSPF-TEOpen Shortest path Fisrt Traffic EngineeringGiao thc nh tuyn OSPF c k thut lu lng

OXCOptical Cross-Connectu ni cho quang

PMDPolarization Mode DispersionTn sc phn cc mt

PPPPoint To Point ProtocolGiao thc im-im

RIPRealtime Internet ProtocolGiao thc bo hiu IP thi gian thc

RSVPWavelength Resvation ProtocolGiao thc t trc ti nguyn

RSVP-TEWavelength Resvation Protocol Traffic EngineeringGiao thc t trc ti nguyn c k thut lu lng

RWARouting and Wavelength Assignmentnh tuyn v gn bc sng

SDHSynchronous Digital HierarchyPhn cp truyn dn s ng b

SLE Static Lightpath EstablishmentThit lp lung quang tnh

SONETSynchronous Optical NetworkMng quang ng b

TCPTransport Control ProtocolGiao thc iu khin truyn ti

TETraffic EngineeringK thut lu lng

TEDTraffic Engineering DataBaseC s d liu k thut lu lng

TDMTime Division MultIPlexerGhp knh phn chia theo thi gian

TVLType Length ValueGi tr chiu di tuyn (s nt)

TWATotal Wavelength and AvailableTng s bc sng v bc sng c th s dng

UDPUser Data ProtocolGiao thc d liu ngi s dng

UNIUser Network InterfaceGiao din mng- ngi s dng

VCIVirtual Circuit IdentifierTrng nhn dng knh o

WCCWavelength Continuity ConstraintRng buc bc sng lin tc

WRNWavelength Routed NetworkMng nh tuyn bc sng

LANLocal Area NetworkMng ni b

PNNIPrivate Network-Network Interface protocolGiao din mng n mng ring

Thut ng vit tt

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CHNG 1TNG QUAN V CNG NGH CHUYN MCHNHN A GIAO THC MPLS V GMPLS

1.1 GII THIUTrong nhng nm gn y cng vi s bng n ca Internet trn ton cu th cc dch v thoi v a phng tin cng ngy cng pht trin vi tc chng mt. Ko theo l vn v tc v di thng ca cc dch v ny vt qu ti nguyn h tng ca Internet hin nay.Nh bit, giao thc nh tuyn TCP/IP c u im l kh nng nh tuyn v truyn gi tin ht sc mm do v linh hot. Tuy nhin nhc im ca n l khng m bo c cht lng dch v, tc truyn tin theo yu cu. Trong khi cng ngh ATM c th mnh u vit v tc truyn tin cao, m bo thi gian thc v cht lng dch v theo yu cu nh trc nhng n li khng c c kh nng nh tuyn mm do nh ca TCP/IP. Gii php c t ra i vi cc nh khoa hc l tm ra mt phng thc chuyn mch c th kt hp ng thi u im ca TCP/IP v ATM. S kt hp c th l gii php k vng cho mng vin thng tng lai- mng th h sau NGN.Chuyn mch nhn l gii php p ng c nhu cu . C l yu t thc y quan trng nht ng sau chuyn mch nhn l nhu cu pht trin chc nng nh tuyn ca Internet v IP. V cng l iu tt yu do i hi ca s pht trin nhanh chng ca Internet.S ra i ca chuyn mch nhn a giao thc MPLS gp phn gii quyt cc vn m cc mng ngy nay ang phi i mt nh tc , lu lng truyn kh nng m rng cp mng, qun l cht lng dch v (QoS). MPLS xut hin p ng cc yu cu dch v v qun l bng thng cho giao thc Internet (IP) th h sau da trn mng ng trc.Ni tm li, s ra i ca MPLS ng mt vai tr quan trng trong vic nh tuyn, chuyn mch v chuyn tip cc gi qua mng th h sau cng nh gii quyt cc vn lin quan ti kh nng m rng mng [13]. N c th hot ng vi cc mng Frame Relay v ch truyn ti khng ng b ATM hin nay p ng cc nhu cu dch v ca ngi s dng.

1.2. CNG NGH IPNh nhc trn MPLS l s kt hp ca hai cng ngh IP v ATM. Nn ti s gii thiu khi qut v hai cng ngh ny.S pht trin t bin ca IP, s tng trng theo cp s nhn ca thu bao Internet l mt thc t khng ai c th ph nhn. Hin nay, lng dch v ln nht trn cc mng ng trc trn thc t u l t IP. Trong cng tc tiu chun ho cc loi k thut, vic m bo tt hn cho IP tr thnh trng im ca cng tc nghin cu.IP l giao thc lin mng phi kt ni. Vic chuyn gi tin thc hin theo c ch phi kt ni. IP nh ngha c cu nh s, c cu chuyn tin, c cu nh tuyn v cc chc nng iu khin mc thp (ICMP). Gi tin IP gm a ch ca bn nhn a ch l s duy nht trong ton mng v mang y thng tin cn cho vic chuyn gi ti ch. T khi giao thc ny ra i, n nhanh chng tr thnh giao thc lin mng thng dng nht. Ngy nay gn nh cc lin mng cng cng s dng giao thc IP. Mng IP c mt khp mi ni, mng Internet ton cu hin nay cng ang s dng giao thc IP.Bn cnh nhng u im tuyt vi ca giao thc IP (nh kh nng nh tuyn), n cng c khng t nhng nhc im (nh kh nng qun l cht lng dch v), cc nh cung cp mng trong qu trnh pht trin lin tc b sung cc giao thc, thut ton mi (chng hn cc giao thc QoS nh: RSVP, IntServ, DiffServ, giao thc IPSec, RTP/RTCP hay cc thut ton tng tc tm kim a ch trong bng nh tuyn) c th khc phc cc nhc im ca mng IP. Nhng ci g cng c gii hn ca n, khi nhu cu s dng dch v ca ngi s dng tng ln c v loi hnh ln cht lng dch v th mi s b sung l khng v cn c nhng cng ngh mng mi c bn cht khc (khng l gii php phi kt ni) p ng yu cu QoS tt hn. V th l nhiu cng ngh mng ra i, in hnh l FR v ATM.Tm li, IP l mt giao thc chuyn mch gi c tin cy v kh nng m rng cao. Tuy nhin, vic iu khin lu lng rt kh thc hin do phng thc nh tuyn theo tng chng. Mt khc, IP cng khng h tr cht lng dch v.[13]1.3. CNG NGH ATMCng vi s pht trin ca Internet v tng tc x l ca b nh tuyn l s pht trin mnh trong lnh vc chuyn mch. Mng s dch v tch hp bng rng (B-ISDN) l mt k thut cho php truyn thng thi gian thc gia cc thit b truyn thng u cui, s dng k thut ATM. ATM c th mang mi lung thng tin nh thoi, d liu, video, phn mnh n thnh cc gi c kch thc c nh (gi l cell), v sau truyn ti cc cell trn ng dn c thit lp trc, gi l kt ni o.Cng ngh ATM da trn c s phng php chuyn mch gi, thng tin c nhm vo cc gi tin c chiu di c nh. Trong , v tr ca gi khng ph thuc vo ng h ng b, v da trn nhu cu bt k ca knh trc. Cc chuyn mch ATM cho php hot ng vi nhiu tc v dch v khc nhau.[13]ATM c hai c im quan trng:- Th nht, ATM s dng cc gi c kch thc nh v c nh gi l cc t bo ATM, cc t bo nh vi tc truyn ln s lm cho tr truyn lan v bin ng tr gim nh i vi cc dch v thi gian thc, cng s to iu kin cho vic kt hp knh tc cao c d dng hn.- Th hai, ATM c kh nng nhm mt vi knh o thnh mt ng o nhm gip cho vic nh tuyn c d dng.ATM khc vi nh tuyn IP mt s im. N l cng ngh chuyn mch hng kt ni. Kt ni t im u n im cui phi c thit lp trc khi thng tin c gi i. ATM yu cu kt ni phi c thit lp bng nhn cng hoc thit lp mt cch t ng thng qua bo hiu. Mt khc, ATM khng thc hin nh tuyn ti cc nt trung gian. Tuyn kt ni xuyn sut c xc nh trc khi trao i d liu v c gi c nh trong sut thi gian kt ni. Trong qu trnh thit lp kt ni, cc tng i ATM trung gian cung cp cho kt ni mt nhn. Vic ny nhm thc hin hai iu: dnh cho kt ni mt s ti nguyn v xy dng bng chuyn t bo ti mi tng i. Bng chuyn t bo c tnh cc b v ch cha thng tin v cc kt ni ang hot ng i qua tng i. iu ny khc vi thng tin v ton mng cha trong bng chuyn tin ca router dng IP.Qu trnh chuyn tip t bo qua tng i ATM cng tng t vic chuyn gi tin qua router. Tuy nhin, ATM c th chuyn mch nhanh hn v nhn gn trn cell c kch thc c nh (nh hn ca IP), kch thc bng chuyn tin nh hn nhiu so vi ca IP router, v vic ny c thc hin trn cc thit b phn cng chuyn dng. Do vy, thng lng ca tng i ATM thng ln hn thng lng ca IP router truyn thng.Do c kh nng h tr truyn d liu, thoi, v video vi cht lng cao trn mt s cc cng ngh bng tn cao khc nhau, ATM tng c xem nh l cng ngh chuyn mch ha hn v thu ht nhiu s quan tm. Tuy nhin, hin nay cng nh trong tng lai h thng ton ATM s khng phi l s la chn ph hp nht.i vi cc ng dng c thi gian kt ni ngn, th mi trng hng kt ni dng nh li khng thch hp do thi gian thit lp kt ni cng nh t l phn thng tin mo u li qu ln. Vi cc loi lu lng nh vy th mi trung phi kt ni vi phng thc nh tuyn n gin, trnh phi s dng cc giao thc bo hiu phc tp s ph hp hn. 1.4. CNG NGH MPLSChuyn mch nhn a giao thc (MPLS) l kt qu ca qu trnh pht trin nhiu gii php chuyn mch IP, c chun ho bi IETF. Tn gi ca n bt ngun t thc t l hon i nhn c s dng nh l k thut chuyn tip nm bn di. S dng t a giao thc trong tn ca n c ngha l n c th h tr nhiu giao thc lp mng, khng ch ring IP. Ngoi ra cc nh cung cp mng c th cu hnh v chy MPLS trn cc cng ngh lp 2 khc nhau nh Fram Relay khng ch ring ATM. V mt kin trc iu ny l ng, nhng trong thc t MPLS thng tp trung vo vic vn chuyn cc dch v IP trn nn ATM.MPLS l gii php nhm lin kt nh tuyn lp mng v c ch hon i nhn thnh mt gii php n nht t c cc mc tiu sau: Ci thin hiu nng nh tuyn Ci thin tnh mm do ca nh tuyn trn cc m hnh xp chng truyn thng. Tng tnh mm do trong qu trnh a v pht trin cc loi hnh dch v mi.Mng MPLS c kh nng chuyn cc gi tin ti lp 3 bng vic s dng x l tng gi v chuyn tip gi tin ti lp 2 s dng c ch hon i nhn. MPLS da trn m hnh ngang cp, v vy mi mt thit b MPLS chy mt giao thc nh tuyn IP, trao i thng tin nh tuyn vi cc thit b ln cn, v ch duy tr mt khng gian cu hnh mng v mt khng gian a ch. MPLS chia b nh tuyn lm hai phn ring bit: chc nng chuyn gi tin v chc nng iu khin. Phn chc nng chuyn gi tin vi nhim v gi gi tin gia cc b nh tuyn IP, s dng c ch hon i nhn tng t nh ca ATM.Trong MPLS nhn l mt thc th c di c nh v khng ph thuc vo lp mng. K thut hon i nhn v bn cht l vic tm chng k tip ca gi tin trong mt bng chuyn tip nhn, sau thay th gi tr nhn ca gi ri chuyn ra cng ra ca b nh tuyn. Vic ny n gin hn nhiu so vi vic x l gi tin thng thng v do vy ci tin kh nng ca thit b. Cc b nh tuyn s dng thit b ny gi l b nh tuyn chuyn mch nhn LSR (Label switching Router). Phn chc nng iu khin ca MPLS bao gm cc giao thc nh tuyn lp mng vi nhim v phn phi thng tin nh tuyn gia cc LSR, v th tc gn nhn chuyn thng tin nh tuyn thnh bng nh tuyn chuyn mch nhn. MPLS c th hot ng c vi cc giao thc nh tuyn Internet nh OSPF (Open Shortest Path First) v BGP (Boder Gateway Protocol) hay PNNI ca ATM. Do MPLS h tr iu khin lu lng v cho php thit lp tuyn c nh nn vic m bo dch v ca cc tuyn l hon ton kh thi. Ngoi ra, MPLS cn c c ch nh tuyn li nhanh (fast rerouting).Bn cnh tin cy, cng ngh MPLS cng h tr vic qun l mng c d dng hn. Do MPLS qun l vic chuyn tin theo cc lung thng tin, cc gi tin thuc mt FEC (Forwarding Equivalence Class - lp chuyn tip tng ng) c th c xc nh bi gi tr ca nhn. Do vy, trong min MPLS, cc thit b o lu lng mng c th da trn nhn phn loi cc gi tin. Bng cch gim st lu lng ti cc b nh tuyn chuyn mch nhn LSR, nghn lu lng nhanh chng c pht hin v v tr xy ra nghn lu lng c th xc nh. Tuy nhin, gim st lu lng theo phng thc ny khng a ra c ton b thng tin v cht lng dch v (v d nh tr xuyn xut ca min MPLS). Vic o tr c th c thc hin bi giao thc lp hai. gim st tc ca mi lung v m bo cc lung lu lng tun th tnh cht lu lng c nh trc, h thng gim st c th dng mt thit b nh dng lu lng. Thit b ny s cho php gim st v m bo tun th c tnh lu lng m khng cn thay i cc giao thc hin c. Khi mt gi tin vo mng MPLS, cc b nh tuyn chuyn mch nhn khng thc hin chuyn tip theo tng gi m thc hin phn loi gi tin vo trong cc lp tng ng chuyn tip FEC, sau cc nhn c nh x vo trong cc FEC. Mt giao thc phn b nhn LDP c xc nh v chc nng ca n l n nh v phn b cc rng buc FEC/nhn cho cc b nh tuyn chuyn mch nhn LSR. Khi LDP hon thnh nhim v ca n, mt ng dn chuyn mch nhn LSP c xy dng t li vo ti li ra. Khi cc gi vo mng, LSR li vo kim tra nhiu trng trong tiu gi xc nh xem gi thuc v FEC no. Nu c mt rng buc nhn/FEC th LSR li vo gn nhn cho gi v nh hng n ti giao din u ra tng ng. Sau gi c hon i nhn qua mng cho n khi n n LSR li ra, lc nhn b loi b v gi c x l ti lp 3. Hiu nng t c y l nh vic a qu trnh x l lp 3 ti bin ca mng v ch thc hin mt ln ti thay cho vic x l ti tng node trung gian nh ca IP. Ti cc node trung gian vic x l ch l tm s ph hp gia nhn trong gi v thc th tng ng trong bng kt ni LSR v sau hon i nhn- qu trnh ny thc hin bng phn cng.Mc d hiu nng v hiu qu l 2 kt qu quan trng, song chng khng phi l cc li ch duy nht m MPLS cung cp. Trong mt ca nhng nh cung cp cc mng ln, th kh nng thc hin k thut lu lng tin tin m khng phi tr gi v hiu nng ca MPLS c quan tm c bit. MPLS thc hin cc chc nng sau: + Xc nh c cu qun l cc tnh ht khc nhau ca cc lung lu lng, nh cc lung gia cc my, phn cng khc nhau hoc thm ch cc lung gia nhng ng dng khc nhau.+ Duy tr s c lp ca cc giao thc lp 2 v 3+ Cung cp phng php nh x a ch IP vi cc nhn n gin, c di c nh c s dng bi cc cng ngh chuyn tip gi v chuyn mch gi khc nhau+ Giao din vi cc giao thc nh tuyn hin c nh giao thc t trc ti nguyn RSVP (Resource Reservation Protocol) v giao thc m ng ngn nht u tin (OSPF) + H tr IP, ATM v giao thc lp 2 Frame RelayTrong MPLS vic truyn d liu xy ra trn cc ng chuyn mch nhn LSPs (Label Switch Path) to ra t u vo n u ra ca mng MPLS dng chuyn tip gi ca FEC no s dng c ch chuyn i nhn. LSPs c thit lp trc khi truyn d liu (kch thch iu khin). Cc nhn (tn nhn dng chnh xc giao thc) c phn b bng vic s dng giao thc phn b nhn LDP (Label Ditribution Protocol) hoc RSVP hoc c i ln (piggybacked) cc giao thc nh tuyn nh giao thc nh tuyn cng min (BGP) v OSPF. Mi gi d liu bc v mang cc nhn trong sut hnh trnh ca chng t ngun ti ch. Bi v cc nhn c di c nh c chn u gi hoc t bo nn c th chuyn mch gi nhanh gia cc tuyn lin kt bng phn cng.1.4.1. Cc khi nim c bn MPLSA. NhnNhn l mt thc th c di ngn, c nh v khng c cu trc bn trong. Nhn xc nh ng m gi s i qua. Nhn khng trc tip m ho thng tin ca mo u lp mng, nh a ch lp mng. Nhn c gn vo mt gi tin c th s i din cho mt FEC m gi tin c n nh.Thng th mt gi c n nh cho mt FEC (hon ton hoc mt phn) da a ch ch lp mng ca n. Tuy nhin nhn khng bao gi l m ho ca a ch . Dng ca nhn ph thuc vo phng tin truyn m gi tin c ng gi. V d cc gi ATM (t bo) s dng gi tr VPI/ VCI nh nhn, Frame Relay s dng DLCI nh nhn, mt on m c chn thm s dng cho nhn. Khun dng on m gm 4 byte c cu trc nh hnh sau.

Hnh 1.1: Dng nhn MPLS chung [9]i vi cc khung PPP hay Ethernet gi tr nhn dng giao thc P-ID (hoc Ethertype) c chn thm vo mo u khung tng ng thng bo khung l MPLS unicast hay multicastB. Ngn xp nhn (Label stack) l mt tp hp c th t cc nhn gn theo gi truyn ti thng tin v nhiu FEC m gi nm trong v v cc LSP tng ng m gi i qua. Ngn xp nhn cho php MPLS h tr nh tuyn phn cp (mt nhn cho EGP v mt nhn cho IGP) v t chc a LSP trong mt trung k LSP. Mi mc trong ngn xp nhn gn lin vi mc phn cp no . iu ny to thun li cho ch hot ng ng hm trong MPLSC. B nh tuyn chuyn mch nhn LSR (Label switching Router)L thit b (Router hay Switch) s dng trong mng MPLS chuyn cc gi tin bng th tc phn phi nhn. C mt s loi LSR c bn nh sau: LSR, LSR bin, ATM-LSR, ATM-LSR binD. Cc lp chuyn tip tng ng FEC (Forwarding Equivalence Classes)Cc lp chuyn tip tng ng (FEC) l khi nim c dng ch mt lp cc gi c u tin nh sau (chng u gi ti chng tip theo nh nhau) qua mng MPLS ngay c khi c s khc bit gia cc gi tin ny th hin trong mo u lp mng.+ Bng chuyn tip chuyn mch nhnL bng chuyn tip nhn c cha thng tin v nhn vo, nhn ra, giao din vo, giao din ra.E. ng chuyn mch nhn LSP (Label Switching Path)L tuyn to ra t u vo n u ra ca mng MPLS dng chuyn tip gi ca mt FEC no s dng c ch hon i nhn. LSP c thit lp trc khi truyn d liu. MPLS cung cp hai la chn cho vic thit lp LSP.nh tuyn theo chng - Mi LSR la chn chng tip theo mt cch c lp cho mt FEC nht nh. Phng php ny ging vi hin nay c s dng trong mng IP. LSR s dng giao thc nh tuyn c sn no nh OSPF, giao din mng - mng ring ATM (PNNI)nh tuyn r rng (explicit) nh tuyn r rng ging nh nh tuyn ngun. LSR li vo (tc l LSR m d liu bt u truyn) xc nh danh sch cc nt m ER-LSP truyn qua. ng dn xc nh c th khng ti u cng c. Dc ng i ti nguyn c th c t trc m bo QoS cho lu lng d liu. iu ny lm gim nh k thut lu lng khp mng, v cc dch v phn bit c cung cp bng vic s dng cc lung da trn cc chnh sch hoc phng thc qun l mng.F. C s d liu nhn.L bng kt ni trong LSR. C cha gi tr nhn FEC c gn vo cng ra cng nh thng tin v ng gi phng tin truyn.G. Gi tin dn nhnGi tin dn nhn l gi tin m nhn c m ho trong . Trong mt vi trng hp, nhn nm trong mo u ca gi tin dnh ring cho mc ch dn nhn. Trong cc trng hp khc, nhn c th c t chung vo trong mo u lp mng v lp lin kt d liu min l y c trng c th dng cho mc ch dn nhn. Cng ngh m ho c s dng phi ph hp vi c thc th m ho v thc th gii m.H. n nh v phn phi nhn.Trong mng MPLS, quyt nh kt hp nhn L c th vi mt FEC M c th l do LSR pha trc thc hin. LSR pha trc sau khi kt hp s thng bo vi LSR pha sau v kt hp . Do vy, cc nhn c LSR pha trc n nh v cc kt hp nhn c phn phi theo hng t LSR pha trc ti LSR pha sau.1.4.2. Thnh phn c bn ca MPLSLSR: L thnh phn quan trng c bn ca mng MPLS. LSR l thit b nh tuyn chuyn mch nhn (Label Switching Router). Thit b ny thc hin chc nng chuyn tip gi thng tin trong phm vi mng MPLS bng th tc phn phi nhn.LSR bin: L thit b nm bin ca mng MPLS. LSRs bin gi hay nhn cc gi thng tin t hay n mng khc nhau (Frame Relay, ATM.) v chuyn tip lu lng ca cc mng ny ln mng MPLS sau khi thit lp LSPs bng vic s dng giao thc bo hiu nhn li vo v phn b lu lng tr li mng truy nhp li ra. LSR bin gn hay loi b nhn cho cc gi thng tin n hoc i ra khi mng MPLS. Cc LSR bin c th l Igress Router (router li vo) hay Egress Router (router li ra).ATM- LSR: S dng giao thc MPLS trong bng iu khin thit lp knh o ATM. Chuyn tip t bo n nt ATM-LSR tip theo.ATM-LSR bin: Nhn gi c nhn hoc khng c nhn phn vo cc t bo ATM v gi cc t bo n nt ATM-LSR tip theo. Nhn cc t bo ATM t ATM-LSR cn k, ti to cc gi t cc t bo ATM v chuyn tip gi c nhn hoc khng nhn.1.4.3. Cc gio thc s dng trong MPLSTham gia vo qu trnh truyn thng tin trong mng MPLS c mt s giao thc nh LDP, RSVP, CR-LDP, MPLS-BGP. Cc giao thc nh RIP, OSPF s dng trong mng router nh tuyn cc gi IP s khng c cp n phn ny.1.4.3.1. Giao thc LDP (Lable Distribution Prtocol)LDP c chun ho trong RFC 3036, n c thit k thit lp v duy tr cc LSP nh tuyn khng rng buc (unconstraint routing). Vng hot ng ca LSP c th l gia cc LSR lng ging (neighbor) trc tip hoc gin tip.

Hnh 1.2 : Vng hot ng ca LDPa. Hot ng ca LDPLDP c 4 chc nng chnh l pht hin LSR lng ging (Neighbor discovery), thit lp v duy tr phin, qung b nhn (label advertisement) v thng bo (Notification). Tng t vi cc chc nng trn , c 4 lp thng ip LDP sau y: Discovery : trao i nh k bn tin Hello nhm loan bo v kim tra mt LSR kt ni gin tip hoc trc tip Session : thit lp, thng lng cc thng s cho vic khi to, duy tr v chm dt cc phin ngang hng LDP. Nhm ny bao gm cc bn tin Initialization, KeepAlive. Advertisement : to ra, thay i hoc xo cc nh x FEC ti nhn. Nhm ny bao gm bn tin Label Mapping, Label Withdrawal, Label Release, Label Request, Label Request Abort. Notification : truyn t thng tin trng thi, li hoc cnh bo.Cc thng ip Discovery c trao i trn UDP. Cc kiu thng ip cn li i hi phn pht tin cy nn dng TCP. Trng hp hai LSR c kt ni lp 2 trc tip th th tc pht hin neighbor trc tip nh sau: Mt LSR nh k gi i bn tin Hello ti cc cng UDP 646 a ch multicast (tt c cc router trong subnet). Tt c cc LSR tip nhn bn tin Hello ny trn cng UDP. n mt thi im no LSR s bit c tt c cc LSR khc m n c th kt ni trc tip. Khi LSR nhn bit c a ch ca LSR khc bng c ch ny th n s thip lp kt ni TCP n LSR . Khi phin LDP c thip lp gia 2 LSR.Phin LDP l phin song hng nn mi LSR hai u kt ni u c th yu cu v gi lin kt nhn. Hnh 1.3 : Trao i thng ip LDP Trong trng hp hai LSR khng c kt ni 2 lp trc tip (neighbor gin tip) th LSR nh k gi bn tin Hello n cng UDP bit ti a ch IP xc nh c khai bo khi lp cu hnh. u nhn bn tin ny c th tr li li bng bn tin Hello khc v vic thit lp cc phin LDP c thc hin nh trn.b. Cu trc thng ip LDPTrao i thng ip LDP thc hin bng cch gi cc LDP-PDU (protocol data unit) thng qua cc phin LDP trn kt ni TCP. Mi LDP-PDU c th mang mt hoc nhiu thng ip, v cc thng ip ny khng nht thit phi c lin quan ti nhau.

c. LDP PDUMi PDU ca LDP bao gm mt header LDP v theo sau l mt hoc nhiu thng ip LDP. Phn header LDP c dng nh sau:

Hnh 1.4: LDP header PDU length (2 octet) : s nguyn ch chiu di ca PDU theo octet, khng tnh trng Version v PDU Length. LDP Identifier (6 octet): xc nh khng gian nhn c cp pht. Bn octet u l gi tr duy nht ton cc nhn dng LSR, nh a ch IP (router ID) c gn cho LSR. Hai octet ny c set v 0 cho khng gian nhn per-platform.nh dng thng ip LDPTt c cc thng ip LDP c cng format nh sau:

Hnh 1.5 : Format thng ip LDPBt U : Bt Unknown, lun l 0 v c tnh LDP khng c kiu bnvtin Unknown. Bng sau y l cc gi tr nh ngha trng Message Tepy:

Hnh 1.6 : Cc loi bn tin LDP

Message Length : Chiu di ca cc trng sau Message Length tinh theo octet (gm Message ID, cc tham s bt buc v tu chn).Message ID i khi c dng lin kt mt s bn tin vi cc bn tin khc nhau, v d mt bn tin p ng s c cng Message ID vi bn tin yu cu tng ng. Cc tham s bt buc v tu chn ph thuc vo cc loi bn tin c gi, chng thng dng kiu m ho TVL (Type-Length-Value). Ni chung, mi th xut hin trong mt thng ip LDP c th c m ho kiu TVL, tuy nhin c t LDP khng phi lc no cng s dng lc TVL.d. Cc bn tin LDP Hello : c trao i khi bt u qu trnh hot ng LDP nh hnh v trn. Initialization : c gi khi bt u mt phin LDP gia 2 LSR trao i cc tham s, cc tu chn cho phin. Cc tham s ny bao gm: Ch phn b nhn. Cc gi tr b nh thi. Phm vi cc nhn s dng trong knh gia 2 LSR .C 2 LSR u c th gi cc bn tin Initialization v LSR nhn s tr li bng KeepAlive nu cc tham s c chp nhn. Nu c mt tham s no khng c chp nhn th LSR tr li thng bo c li v phin kt thc. KeepAlive : c gi nh k khi khng cn bn tin no cn gi n bo cho mi thnh phn LDP bit rng thnh phn LDP khc ang hot ng tt. Trng hp khng t xut hin bn tin KeepAlive hay mt s bn tin LDP khc trong khong thi gian nht nh th LSR se xc nh i tc LDP hng hoc kt ni c s c v phin LDP chm dt Label Mapping : c s dng qung b gn kt gia FEC v nhn. Label Withdrawal: Thc hin qu trnh ngc li vi bn tin Label Mapping. N c s dng xo b gn kt thc hin trong Label Mapping. Bn tin ny c s dng trong trng hp: Khi c s thay i trong bn tin nh tuyn (thay i prefix a ch), lc LSR khng cn nhn ra FEC ny na Thay i trong cu hnh LSR lm tm dng vic chuyn nhn cho cc gi trong FEC Label Release : c s dng bi LSR khi nhn c chuyn i nhn m n khng cn thit na. iu thng xy ra khi LSR gii phng nhn thy nt tip theo cho FEC khng phi l LSR qung b lin kt nhn/FEC . Label Request : S dng trong ch hot ng gn nhn theo yu cu, LSR se yu cu gn nhn t LSR k cn pha downstream bng bn tin ny. Label Request Abort : Nu bn tin Label Request cn phi hu b trc khi c chp nhn (do nt k tip trong FEC yu cu thay i), th LSR yu cu s loi b yu cu bn tin trc bng bn tin Label Request Abort.e. LDP iu khin c lp v phn phi theo yu cuV d di y minh ho vic s dng bn tin Label Request v Lbel Mapping trong ch cng b nhn theo yu cu v iu khin LSP c lp. Trnh t thi gian trao i cc bn tin LDP gia cc i tc (peer) thit lp mt LSP t ruoter li vo R1 qua R2 ri n router li ra R3 cho mt FEC c prefix a.b/16. R1 khi to tin trnh bng cch yu cu mt nhn cho FEC a.b/16 t hop k ca n l R2. V s dng iu khin c lp nn R2 tr ngay mt nh x nhn v cho R1 trc khi R2 nhn c nh x nhn t pha downstream l R3. C R2 v R3 p ng bng bn tin Label mapping, kt qu l trong FIB ca R1 v LFIB ca R2, R3 c cc entry gn kt nhn hnh thnh nn ng chuyn mch nhn LSP.

Hnh 1.7: V d LDP ch iu khin c lp theo yu cu [15]

LDP cn h tr cc ch phn phi nhn khc. Khi cu hnh ch cng b khng yu cu (downstream unsolicited), cc router s khng dng bn tin Label Request. Nu iu khin tun t, nh x nhn din ra u tin router li ra, ri sau ln lt ngc v n router li vo.1.4.3.2. Giao thc CR-LDP (Constrain-based routing LDP)CR-LDP l giao thc m rng t giao thc LDP (RFC 3212) nhm h tr c bit cho nh tuyn rng buc, k thut lu lng (TE) v cc hot ng d tr ti nguyn. Cc kh nng ca CR-LDP bao gm thng lng cc tham s lu lng nh cp pht bng thng, thit lp v cm gi quyn u tin.a. M rng cho nh tuyn rng bucCR-LDP b sung thm cc i tng Type-Length-Value mi sau y (RFC 3212): Tuyn tng minh ER (Explicit Route) Chng tng minh ER-Hop (Explicit Route Hop) Cc tham s lu lng S ln chim (Preemption) Nhn din LSP (LSPID) Ghim tuyn (Route Pinning) Lp ti nguyn (Resource Class) CR-LSP FECMt s th tc mi cng c b sung h tr cc chc nng cn thit nh: Bo hiu ng (Path Signalling) nh ngha cc tham s lu lng Qun l LSP (quyn u tin, cam kt qu tr, v.v..)CR-LDP s dng c ch gn nhn theo yu cu v iu khin tun t. Mt LSP c thit lp khi mt chui cc bn tin Label Request lan truyn t Ingress-LSR n Egress-LSR, v nu ng c yu cu tho mn cc rng buc (v d bng thng kh dng), th cc nhn mi c cp pht v phn phi bi mt chui cc bn tin Label Mapping lan truyn ngc v Ingress-LSR. Vic thit lp mt CR-LDP c th tht bi v nhiu l do khc nhau v cc li s c bo hiu bng bn tin Notification.

b. Thit lp mt CR-LSP(Constrain-based routing LSP) thit lp mt LSP theo con ng nh trc, CR-LSP s dng i tng tuyn tng minh ER (Explicit Route). ER c cha trong cc bn tin LABEL

Hnh 1.8 : Thit lp LSR vi CR-LDP

Xt v d trong hnh 32. Gi s LSR A mun thit lp mt con ng tng minh l B-C-D. thc hin vic ny, LSR A xay dng i tng ER cha tun t 3 nt tru tng l LSR B, LSR C, LSR D. Mi nt c i din bng mt a ch IP prefix. LSR A sau xy dng mt bn tin Label Request c cha i tng ER mi to. Khi bn tin c to xong, LSR A s xem xt nt tru tng u tin trong i tng ER l LSR B, tm kt ni n LSR B v gi bn tin Label Request trn kt ni . Khi LSR B nhn bn tin Label Request , LSR B nhn thy n l nt tru tng u tin trong i tng ER. LSR B sau tm kim nt tru tng k tip l LSR C v tm kt ni n LSR C. Sau LSR B thay i i tng ER v gi bn tin Label Request n LSR C, lc ny i tng ER ch gm LSR C v LSR D. Vic iu khin bn tin ny ti LSR C cng tng t nh LSR B.Khi bn tin n LSR D, LSR D nhn thy rng n l nt cui cng trong i tng ER. V vy, LSR D to mt bn tin Label Mapping v gi n ngc v LSR C. Bn tin ny bao gm i tng nhn. Khi nhn bn tin ny, LSR C dng nhn cha trong bn tin cp nht LFIB. Sau , LSR C gi bn tin Label Mapping n LSR B. Bn tin ny cng cha nhn m LSR C qung b. Vic iu khin bn tin Label Mapping LSR B hon ton tng t nh LSR C. Cui cng, LSR A nhn c bn tin v LSP c thit lp theo con ng nh tuyn tng minh cho trc mang thng tin v ti nguyn cn d tr.c. Tin trnh d tr ti nguyn

Hnh 1.9: Tin trnh d tr ti nguyn [14]Tin trnh d tr ti nguyn nh trong hnh trn. Khi mt nt CD-LDP nhn c mt bn tin Label Request, n gi Admission Control kim tra xem nt ny c cc ti nguyn c yu cu khng. Nu c ti nguyn kh dng, Admission Control d tr n bng cch cp nht bng Resource. Sau bn tin Label Request c chuyn tip n cc nt MPLS k sau.Khi nt CR-LSP nhn c bn tin Label Mapping, n lu thng tin v giao din vo bng LIB, lu thng tin CR-LSP c yu cu vo bng c s thng tin nh tuyn tng minh ERB (Explicit Route information). Ri n gi Resource Manager to mt hng i phc v cho CR-LSP c yu cu, v lu ServiceID ca n vo bng ERB. Cui cng, n chuyn tip bn tin LSP Mapping ti nt MPLS k trc.

1.4.3.3. Giao thc RSVP-TE ( RSVP Traffic Engineering)RSVP c mt s c ch cn thit thc hin bo hiu phn phi nhn nhm rng buc nh tuyn. IETF chun ho phn m rng k thut lu lng RSVP-TE, nh ngha cc ng dng ca RSVP-TE nh h tr phn phi nhn theo yu cu cp pht ti nguyn cho cc LSP nh tuyn tng minh. Tng kt cc cch dng RSVP-TE h tr ti nh tuyn make-before-break, theo di ng thc s c chn qua chc nng ghi nh tuyn cng nh h tr u tin v ln chim.Nguyn l chc nng ca RSVP l thit lp cc d tr cho lung gi n hng. Cc bn tin RSVP thng i theo con ng hop-by-hop ca nh tuyn IP nu khng hin din tu chn tuyn tng minh. Cc router hiu RSVP dc theo ng c th chn v x l bt c bn tin no, RFC 2205 nh ngha 3 kiu bn tin RSVP: thit lp d tr (reservation setup), tear down, v error. RSVP-TE cng nh ngha thm bn tin Hello.a. Cc bn tin thit lp d tr RSVPRSVP s dng khi nim d tr u nhn. Trc tin u gi pht ra mt bn tin PATH nhn din mt lung v cc c tnh lu lng ca n. Bn tin PATH cha mt session-ID, sender-template, label-request, sender-Tspec v tu chn l i tng tuyn tng minh ERO (explicit route object). Session-ID cha mt a ch IP ch i km mt nhn dng hm 16 bit (tunnel ID) nhn din mt ng hm LSP. Nh trnh by trn, ch c ingress-LSP mi cn bit v FEC c gn vo mt ng hm LSP. Do , khng ging nh LDP, FEC nh x vo ng hm LSP khng bao gm trong bt k bn tin RSVP no. i tng labe-request h tr ch cng b nhn theo yu cu. Sender-template cha a ch IP ca u gi i km vi mt LSP ID c h tr phng thc make-before-break khi thay i ng i ca mt ng hm LSP. c tnh lu lng Tspec s dng tc nh (peak rate), thng token (token bucket) nh ngha tc v kch c bng pht, n v khng ch ti thiu (minimum policed unit) v kch thc gi ti a.Khi bn tin PATH i n ch, bn nhn p ng bng mt bn tin RESV nu c ng khi to vic gn kt nhn c yu cu trong bn tin PATH. Bn tin RESV c truyn theo hng ngc chiu vi bn tin PATH bng cch dng thng tin hop k trc bn tin PATH tng ng, i tng ghi tuyn tu chn (route record) v thng tin l thuc kiu d tr (reservation style). Kiu FF (fixed filter) c mt nhn v Tspec c n nh cho mi cp sender-receiver. Kiu (shared explicit) n nh mt nhn khc nhau cho mi sender, nhng tt c chng phi p dng cng mt d tr lung r rng. i tng record-route ghi nhn tuyn ng thc t c chn bi LSP bt u t egress dn ngc v ingress. N c th c chn mt router dng ghim mt tuyn tng minh th lng bng cch copy tuyn ghi c trong bn tin RESV sang i tng tuyn tng minh ERO trong mt bn tin PATH c gi theo chiu ngc li.b. Cc bn tin Tear Down, Error v Hello ca RSVP-TERSVP-TE nh ngha 2 bn tin dnh cho vic gii to LSP l PATH TEAR v RESV TEAR. Hai bn tin ny c gi theo chiu ngc vi bn tin PATH v RESV tng ng. Bn tin TEAR xo b bt k trng thi ci t lin quan n bn tin PATH hay RESV. Cc bn tin TEAR cng c th dng xo cc trng thi p ng cho mt li bc u tin trong hot ng ti nh tuyn.C cc bn tin thng bo li cho bn tin PATH v RESV CONFIRMATION tu chn. Cc bn tin li cho bit s vi phm chnh sch, m ho bn tin hoc mt s c khc. V d, khi LSP thy rng n khng th h tr Tspec c t trong bn tin RESV, n s khng chuyn tip bn tin RESV v cho pha upstream, thay vo n to ra mt bn tin RESVERR gi cho pha downstream xo b n lc thit lp LSP. Tuyn tng minh v cch tu chn record-route ca RSVP-TE c mt s cc m li phc v cho vic debug.RFC 3209 nh ngha bn tin Hello tu chn cho RSVP-TE, n cho php mt LSR pht hin mt neighbor b li nhanh hn khi so vi RSVP lm ti tnh trng hoc pht hin li ng truyn bng mt giao thc nh tuyn IP. iu ny kh hu ch trong vic ti nh tuyn nhanh.c. Thit lp tuyn tng minh iu khin tun t theo yu cu Vic trao i bn tin RSVP-TE s dng i tng tuyn tng minh ERO ci t mt LSR i qua mt con ng khng phi l ng ngng nht. Router R1 xc nh rng n s n nh FEC a.b/16 cho mt ng hm LSP, v n tnh ra mt tuyn tng minh R4-R5-R3 i n hop k cho FEC . R1 khi to vic thit lp LSP ny bng cch pht ra mt bn tin PATH n R4 vi mt ERO, Tspec, sender template ( c cha a ch ca sender) v mt i tng label request. Mi bn tin RESV lin quan n ng hm LSP ny u mang session-ID v filter-spec nguyn thu ca sender R1 gi mi tng quan vi nhau. Tip theo, R4 tip nhn yu cu ny v gi bn tin PATH n router k tip ghi trong ERO l R5. n lt mnh, R5 gi bn tin ny n egerss-router R3.Ti ch n ca bn tin PATH, R3 xc nh lin kt chng R3-R5 c th h tr cho yu cu v l hop cui cng trn ng dn cho FEC a.b/16. R3 p ng bng bn tin RESV c cha ERO, Tspec ca dung lng d tr, mt filter spec tho mn bn gi, v gn mt nhn null ngm (implicit null) cho chng lin kt ny. Theo RFC 3031, nhn null l mt quy c c dng trong phn phi nhn cho php egress-router ( y l R3) bo hiu cho i tc upstream ca n bit rng y l hop p cui (penultimate hop) ca LSP, do vy cn g nhn nh ca stack (xem LEIB ca LSR R5). Tip theo, R5 thu np bn tin RESV yu cu cho chng R5-R4, n nh nhn B v gi bn tin RESV n router k trc trong ERO l R4. Cui cng, R4 chp nhn yu cu, n nh nhn A v gi bn tin RESV ngc v R1. n lc ny, ng LSP c thit lp xong v cc gi c nhn cho FEC a.b/16, c chuyn tip qua ng hm.

Hnh1.10 : Thit lp LSP vi RSVP-TE [15]Khc vi giao thc LDP, cc bn tin RSVP-TE khng mang FEC, v ch duy nht c R1 cn bit v nh x gia FEC v ng hm LSP.d. Gim lng overhead lm ti RSVPRSVP l giao thc trng thi mm (soft-state), tin trnh pht mt bn tin PATH v bn tin RESV hi p tng ng phi c nh k lm ti, thng khong 30s mt ln. Phng php lm ti ny phng cc bn tin b mt v trong trng hp nh tuyn tng chng s t ng chuyn d tr ti nguyn sang ng mi khi c bt k thay i nh tuyn IP. Tt nhin, vic x l dnh cho khi to cc bn tin PATH v RESV ln hn nhiu co vi vic lm ti trng thi mt bn tin nhn c trc , tuy nhin vi mt s lng ln cc LSP th vic x l lm ti c nh hng ng k n hiu nng.Mt cch gii quyt l tng chu ky lm ti, nhng cng s lm tng tr bo hiu khi mt bn tin. RFC 2961 miu t mt gii php cho hn mc x l v vn tr bo hiu. C ch ny bao gm vic b gn bn tin gim ti x l, cng nh cc bn tin PATH TEAR v RESC TEAR v hai bn tin ny khng c lm ti trong hot ng RSVP. Cui cng, gii php ny nh ngha mt bn tin tng kt (summary) lm ti trng thi m khng yu cu truyn ton b bn tin lm ti. Cc ci tin ny nhm gim lng overhead lm ti ca RSVP trong mng MPLS.1.4.3.4. Giao thc BGPBGPv4 v m rng cho MPLSBGPv4 (Border Gateway protocol ) l mt giao thc nh tuyn gn kt tp hp cc mng cung cp dch v trn internet. V n ch l giao thc s dng gia cc nh cung cp mng, RFC 2107 m rng BGP h tr phn phi nhn MPLS c th thip lp cc LSP lin mng.BGP c mt tp thut ng ring. Mt khi nim quan trng l s AS duy nht (Autonomous System), c nh ngha l mt tp hp router thc hin mt chnh sch nh tuyn ngoi thng nht c th nhn thy i vi router ca AS khc. BGP khng truyn cc thng tin cu hnh ni gia cc AS, n ch cung cp cc thng tin v cc prefix a ch m c th tm n hoc i qu giang qua . S dng BGP gia cc router bin (border) ni trong mt AS c gi l BGP ni (iBGP), cn s dng BGP gia cc router trong cc AS khc nhau gi l BGP ngoi (eBGP).BGP chy trn mt phin TCP v n cn tin cy, phn pht ng th t. N c 3 phase hot ng : thit lp phin, trao i bn tin cp nht, v chm dt phin. Trong thit lp phin, cc i tc BGP (BGP peer) trong cc AS ln cn trao i cc bn tin OPEN c cha AS number, mt gi tr keep-alive timeout, v cc tham s tu chn nh nhn thc. Cc BGP peer nh k trao i bn tin keep-alive, nu pht hin timeout s chm dt phin. Sau khi thit lp phin, cc BGP peer trao i cc bn tinUPDATE c cha cc prefix a ch c th n c hin hnh (reachability), c gi l NLRI (Network Layer Reachbility Information). Sau khi trao i ng b bn tin khi to, cc thay i nh tuyn gia tng c lin lc bng bn tin UPDATE.Ni dung bn tin BGP UPDATE gm 3 phn : cc tuyn thu hi (withdraw route), mt danh sch cc prefix a ch NLRI, v mt danh sch tu chn cc thuc tnh lin quan. Cc BGP peer to quyt nh chnh sch cc b khi xem xet cng b mt NLRI vi cc thuc tnh ng c chn hay thu hi thng co trc . Chnh sch thng dng l chn NLRI c prefix a ch miu t trng nht, chn mt ng c s hop AS it nht.

Hnh 1.11: Ni dung bn tin BGP update [15]Khi bn tin UPDATE cha thng tin NLRI, mt s thuc tnh ng l bt buc trong khi mt s khc l tu chn. Cc thuc tnh ng bt buc l : ORIGIN, AS-PATH, v NEXT-HOP. ORIGIN nhn din ngun gc ca NLRI, th d n c hc qua giao thc nh tuyn ni hay ngoi. AS-PATH lit k mt path-vector gm mt tp AS i qua n thi im hin ti (mt chui th t cc AS). V chiu di ca AS-PATH thng l yu t quyt nh mt tuyn, nn BGP c gi l giao thc nh tuyn path-vector. Cc router s dng AS-PATH trnh loop bng cch khng chuyn tip cc thng co tuyn c cha s AS ca chng. NEXT-HOP nhn din a ch IP ca router bin cn dng tm n NLRI. BGP c mt tham s tu chn c th thc hin mt dng cn bng ti: LOCALPREF v MED. LOCALPREF cho php AS u gi ch nh mt s u tin (preference) nh tuyn lu lng i ra trn nhiu lin kt AS khc; trong khi MED (multIPle exit discriminator) cho php mt AS pha nhn ch nh mt u tin cho lu lng n t mt AS khc.RFC 2238 nh ngha cc m rng a giao thc cho BGP phn phi nhn MPLS nm trong mt phn ca NLRI. Cc BGP peer thng lng h tr cho kh nng tu chn ny vo lc thit lp phin. Th tc c bn l k sinh vic phn phi nhn theo kiu khng yu cu song song khi thc hin phn phi tuyn BGP.1.5. CNG NGH GMPLS1.5.1 Gii thiuVi s bng n nhu cu lu lng trong nhng nm gn y, mng quang c xem l gii php hu hiu p ng nhu cu. Cc h thng SDH, WDM v cc thit b u ni cho OXC cng pht trin mnh m nhm tng dung lng v phm vi mng. Mng iu khin quang c thit k nhm n gin ho, tng tnh p ng v mm do trong vic cung cp cc phng tin trong mng quang. MPLS tr thnh m hnh nh tuyn mi cho mng IP. GMPLS l s m rng ca MPLS nhm hng ti mng iu khin quang cho mng quang.IETF v OIF pht trin tiu chun GMPLS m bo s phi hp gia cc lp mng khc nhau. Hin ti lp truyn ti (lp quang) v lp s liu (in hnh l Lp 2 v/hoc IP) tch hn nhau v hot ng c lp nhau. GMPLS tp hp cc tiu chun vi mt giao thc bo hiu chung cho php phi hp hot ng, trao i thng tin gia lp truyn ti v lp s liu. N m rng kh nng nh tuyn lp s liu n mng quang. GMPLS c th cho php mng truyn ti v mng s liu hot ng nh mt mng ng nht. [7]GMPLS c pht trin trong n lc nhm lm n gin ho v b bt m hnh mng bn lp hin ti. GMPLS loi b cc chc nng chng cho gia cc lp bng cch thu hp cc lp mng. N khng phi l mt giao thc n hay tp khng i cc giao thc, m l phng thc kt hp nhiu k thut trn cng mt kin trc n v qun l chng vi mt tp n cc giao thc qun l [13]Nhiu cng ty hin ang trin khai mng GMPLS n gin vic qun l mng v to ra mt mt phng iu khin tp trung. iu ny cho php to ra nhiu dch v hn cho khch hng trong khi gi thnh hot ng li thp. GMPLS cng ha hn s mang li cht lng dch v tt hn v thit k lu lng trn internet, mt xu hng hin ti v cng l mc tiu chnh ca bt c nh cung cp dch v no. 1.5.2 Hot ng v nn tng ca MPLSMPLS m rng b giao thc IP nhm ci thin qu trnh pht chuyn ca cc Router. i vi cc Router, khi nhn c mt gi tin phi qua qu trnh phn tch a ch v tm kim tuyn kh phc tp xc nh trm k tip bng cch kim tra a ch ch trong header ca gi. MPLS n gin th tc ny bng cch da vo mt nhn n gin khi pht chuyn. MPLS cn c kh nng t cc lu lng IP trn cc ng xc nh trc qua mng. Bng cch ny MPLS to ra s bo m v bng tn v cc c tnh dch v khc cho mi ng dng c th ca User (ngi s dng). Vi mi dch v c th, mt bng lp pht chuyn tng ng (FEC) biu din mt nhm cc dng lu lng c cng yu cu v x l lu lng c to ra. Mt nhn c bit sau c dng gn cho mt FEC. Ti li vo mng MPLS, cc gi IP n c c kim tra v gn mt nhn bi router nhn bin mng (LER). Cc gi c gn nhn sau c pht chuyn dc theo mt LSP v ti y cc Router chuyn mch nhn (LSR) da vo trng nhn trong gi a ra quyt nh chuyn mch. LSR khng cn kim tra tiu IP ca gi tm trm k tip. N n gin ch b nhn hin ti v a vo mt nhn mi cho trm k tip. C s thng tin nhn to ra cc nhn mi ( chn vo gi) v mt giao din ra (da vo nhn vo trn giao din vo).Bo hiu thit lp LSP x l lu lng c thc hin nh s dng giao thc phn phi nhn trn mi nt MPLS. C mt s giao thc phn phi nhn khc nhau trong hai giao thc ph bin nht l RSVP- x l lu lng (RSVP-TE) v CR-LDR. RSVP-TE l phin bn m rng ca RSVP phn phi cc nhn v to kh nng x l lu lng. CD-LDP c thit k ring cho mc ch ny.MPLS gm c cc m rng ca cc giao thc nh tuyn trng thi tuyn IP hin ti, cc m rng MPLS i vi OSPF v IS-IS cho php cc nt khng ch trao i cc thng tin v topo mng m nhng thng tin v ti nguyn v thm ch v chnh sch cng c trao i. Thut ton nh tuyn da trn cc rng buc s dng cc thng tin ny tnh ton cc ng ti u cho cc LSP v cho php thc hin cc quyt nh v qu trnh x l lu lng phc tp mt cch t ng khi chn tuyn qua mng.1.5.3 Qu trnh pht trin MPLS n GMPLSIETF m rng b giao thc MPLS c kh nng h tr c cc thit b chuyn mch theo thi gian, bc sng v khng gian qua GMPLS. iu ny cho php mng da trn GMPLS xc nh v cung cp ng ti u da trn cc yu cu lu lng ca user (ngi s dng). Mt s cu trc GMPLS c ch ra nh bng sau:

Min chuyn mchLoi lu lng Lc pht chuynThit b in hnhThut ng

Gi , cellIP, ATMNhn nh phn ghp thm vo header, kt ni knh o (VCC)IP router , ATM switchKh nng chuyn mch gi (PSC)

Thi gianTDM/SNOETKhe thi gian trong chu k lp liH thng kt ni cho s DCS, ADMKh nng TDM

Bc sngTrong sut Lambda DWDMKh nng chuyn mch Lambda (LSC)

Khng gian vt lTrong sutFiber , lineOXCKh nng chuyn mch quang

Hnh 1.12 : Mt s cu trc GMPLS [7]

Khc bit gia MPLS v GMPLSGMPLS c m rng t MPLS, tuy nhin trong khi MPLS hot ng trong mng s liu th GMPLS c ng dng trong mng iu khin, thc hin qun l kt ni cho mng s liu gm c chuyn mch gi, chuyn mch knh (nh TDM, chuyn mch bc sng v chuyn mch si).Mt im khc na gia MPLS v GMPLS l MPLS yu cu lung chuyn mch nhn (LSP) thit lp gia cc b nh tuyn bin, trong khi GMPLS m rng khi nim LSP, LSP trong GMPLS c th thit lp gia bt k kiu b nh tuyn chuyn mch nhn nh nhau no bin mng. Chng hn, c th thit lp LSP gia cc b ghp knh ADM-SDH to nn TDM-LSP hoc c th thit lp gia hai h thng chuyn mch to nn LSC-LSP hoc gia cc h thng ni cho chuyn mch si to nn FSC-LSP.

1.5.4 B giao thc GMPLSS pht trin MPLS thnh GMPLS m rng giao thc bo hiu (RSVP-TE, CR-LDP) v giao thc nh tuyn (OSPF-TE, IS-IS-TE). Cc m rng ny gm cc c tnh mng quang v TDM/SONET. Giao thc qun l tuyn l mt giao thc mi qun l v bo dng mt phng iu khin v mt phng s liu gia hai nt ln cn. LMP l giao thc da trn IP bao gm c cc m rng i vi RSVP-TE v CR-LDP

Bng sau tm tt cc giao thc v cc m rng ca GMPLS: nh tuynOSPF-TE, IS-IS-TEGiao thc nh tuyn dng cho vic khm ph mt cch t ng v poto mng, hin th cc ti nguyn kh dng. Mt s tng cng chnh gm :1, Cho bit loi bo v tuyn (1+1, 1:1, khng bo v)2, Nhn v thng bo cc lin kt khng c a ch IP-ID link.3, Giao din ID vo, ra4, Khm ph tuyn khc nhau cho d phng

Bo hiuRSVP-TE,CR-LDPGiao thc bo hiu dng cho qu trnh thit lp cc LSR mang lu lng. Cc tng cng chnh gm:1, Trao i nhn, bao gm c cc mng khng phi chuyn mch gi.2, Thit lp cc LSR 2 hng 3, Bo hiu thit lp ng d phng4, Thc y vit gn nhn thng qua cc nhn c xut4, H tr chuyn mch bng tn tp cc bc sng gn nhau c chuyn mch vi nhau

Qun l tuynLMPQun l knh iu khin : c thit lp bi cc tham s tuyn v m bo s an ton cho c tuyn.

Kim tra vic kt ni tuyn : n bo kt ni vt l tuyn gia cc nt ln cn, s dng mt PING nh mt bn tin kim tra.

Lin kt cc c tnh tuyn : Xc nh cc c tnh tuyn ca cc nt gn k

C lp li : C lp cc li n hoc li kp trong min quang

Hnh 1.13 : Cc giao thc v cc m rng ca GMPLS [7]Trong ngn xp, giao thc nh tuyn IS-IS-TE tng t vi OSPF-TE nhng thay v dng IP, giao thc mng phi kt ni (CLNP) s dng mang cc thng tin IS-IS-TE.

Hnh 1.14 : Ngn xp giao thc GMPLS [11], [5]1.5.5 Mc tiu v cc chc nng mt phng iu khin GMPLSMt phng iu khin GMPLS trc ht gii quyt vn qun l kt ni, bao gm c cc dch v kt ni theo kiu gi v knh, cc kha cnh ca qu trnh qun l tnh ton, qun l thc hin, an ton v qun l chnh sch. Mt phng iu khin GMPLS c bn l mt mt phng iu khin kt ni phn tn da trn IP. iu ny khng loi tr vic s dng GMPLS kt hp vi cc gii php khc nh h thng mng qun l tp trung. Sau y xem xt mt s chc nng mc cao v cc yu cu dch v ca GMPLS. T ng hot ng: Mt phng iu khin bao gm cc chc nng qun l phn tn v cc giao din cn thit cho qu trnh qun l kt ni t ng trong mng. Mt trong cc mc tiu c bn ca mt phng iu khin l cc hot ng t ng. Mt phng iu khin phn tn GMPLS c th cung cp cc kh nng iu khin mng tng cng v gim cc hot ng phc tp, tn nhiu thi gian khng cn thit. ng thi n cng thun tin cho vic phi hp hot ng v kt hp gia mng vi cc k thut mt phng s liu khc. Ti u vic la chn ng: Vic la chn cc tuyn trong mng iu khin bi GMPLS c th c ti u ho m bo tnh hiu qu, s dng ti nguyn mng hiu qu v cc thc hin tho mn yu cu khc. Phc hi nhanh cc ng s liu: Vic phc hi ny c th c thc hin nh la chn tuyn trc lc xy ra s c (offline) hoc c tnh ton ng ngay thi im c s c (online). Vic tnh ton online v c ch phc hi phn tn s mang li thi gian hi phc nhanh hn so vi phng php hin ti ca NMS tp trung. Khi cc s c mng xy ra ng thi th vn hi phc s tr nn phc tp. m bo cc yu cu v hi phc s liu, mt phng iu khin DCN phi c thit k tin cy. X l cnh bo: Cc cnh bo lin quan n mt phng iu khin do chnh cc thc th qun l phi c thng bo cho mt phng iu khin. Vic x l cnh bo ph thuc vo mt phng qun l. c trng hn, GMPLS da trn mt phng iu khin phn tn bao quanh cc mng truyn ti a lp cn p ng c cc yu cu sau: Tnh kh m: Qu trnh thc hin ca mt phng iu khin khng nn ph thuc nhiu vo kch thc mng dng GMPLS (chng hn s nt, s lin kt vt l). Mt phng iu khin cn duy tr thc hin n nh cng nhiu cng tt so vi kch thc mng. Tnh mm do: Mt phng iu khin phi c mm do v mt chc nng v cung cp cc iu kin hot ng v cu hnh.1.5.6 Kin trc cc thnh phn ca mt phng iu khin GMPLS1.5.6.1 Yu cu ca mt phng iu khin Mt phng iu khin v mt phng s liu hot ng m bo tin cy l vn sng cn i vi mng quang. Mt phng iu khin phi c thit k sao cho khi xy ra cc s c th cc kt ni cng khng b nh hng. V ngay c khi cc kt ni b hng trong trng hp mt phng s liu c s c th mt phng iu khin cng phi c kh nng nh tuyn li. Nhn chung mt phng iu khin GMPLS cn: C kh nng p ng cho tt c cc mng chuyn mch gi v mng chuyn mch knh nh IP, ATM, OTN, SONET/SDH. linh hot thch nghi vi cc kch bn mng khc nhau (cc m hnh kinh doanh ca cc nh cung cp dch v). Mc tiu ny t c bng cch chia mt phng iu khin thnh cc thnh phn chc nng khc nhau. Mi thnh phn c th yu cu nhiu cng c cho cc kch bn mng khc nhau. Mi cng c cn c kh nng cu hnh v m rng. iu ny cho php cc nh cung cp thit b v cc nh cung cp dch v quyt nh sp xp logic cc thnh phn ny, v cng cho php nh cung cp dch v thc hin cc chnh sch cng nh vn an ton mng.V mt chc nng, mt phng iu khin GMPLS c th chia thnh cc thnh phn nh: Khm ph ti nguyn ln cn v qun l kt ni, nh tuyn, bo hiu. Mt phng iu khin GMPLS cn mt mng trao i s liu to cc bn tin iu khin. N c cc giao din cho mt phng qun l v phn t mng nh b iu khin h thng, c cu chuyn mch.

1.5.6.2 Mng thng tin s liu h tr mt phng iu khin GMPLSMt phng iu khin GMPLS bao gm cc b iu khin phn tn trao i v phi hp vi nhau nhm hon tt cc hot ng kt ni. Mng thng tin s liu (DCN) cn thit trao i cc bn tin iu khin gia cc b iu khin. i vi mng IP truyn thng, khng c mt phng iu khin ring v iu khin v lu lng s liu User dng chung mt mng. i vi cc mng mch, cn mt mng s liu c lp v mt chuyn mch knh in hnh khng x l lu lng User trong mt phng truyn ti ca n. mt phng iu khin GMPLS c kh nng p ng cc mng mch, khi nim DCN phi c gii thiu. DCN h tr mt phng iu khin GMPLS c th s dng cc loi mi trng vt l: Lu lng iu khin c th c truyn qua mt knh thng tin trong s cc lin kt mch mang s liu gia cc LSR. Chng hn mi trng c th l cc byte tiu SONET/SDH hoc OTN. Lu lng iu khin c th c truyn qua knh thng tin ring, chia s cng lin kt vt l vi cc knh s liu. Chng hn, mi trng c th l bc sng ring, mt STS-1 hoc mt DS-1. Lu lng iu khin c th truyn qua mt lin kt thng tin ring gia cc LSR, ring bit so vi cc lin kt mang s liu. Chng hn mi trng c th l mt LAN ring bit hoc mt lin kt im-im.a. Cc yu cu mt phng iu khin GMPLS i vi DCNCc hot ng ca mt phng iu khin GMPLS ph thuc nhiu vo DCN khi trao i cc bn tin iu khin. Do , DCN phi p ng cc yu cu sau: DCN h tr mt phng iu khin GMPLS cng phi h tr IP. DCN phi cung cp thng tin (trc tip hoc gin tip) gia bt k hai LSR no cn trao i lu lng iu khin DCN phi an ton: Yu cu ny xut pht t hai kha cnh nh tuyn v bo hiu. Thc t, thng tin nh tuyn c trao i qua mt phng iu khin l c trng ca nh cung cp dch v. Nh cung cp dch v khng mun tit l cc thng tin trong mng ra ngoi bin mng ca h, thm ch cho chnh cc khch hng ca h. Trong khi , mng mt phng iu khin phi ngn chn tt c tn cng ca cc dch v kt ni. DCN phi tin cy v cung cp kh nng chu ng li. DCN l h thng truyn ti cho cc bn tin mt phng iu khin GMPLS. Nu DCN li, khng bn tin GMPLS no c trao i gia cc b iu khin GMPLS. tin cy ca DCN phi c m bo ngay c khi mng truyn ti dch v c cc li nng xy ra. DCN phi h tr chc nng u tin pht chuyn bn tin. Qu trnh thchin tng th ca mt phng iu khin GMPLS ph thuc nhiu vo vic truyn ti cc bn tin iu khin ca chng. Cc hot ng nhy cm vi thi gian nh chuyn mch bo v cn m bo QoS mc c bn. Hn na, vic truyn cc bn tin cn c m bo hoc khi phc nhanh chng ngay c khi mng c s c DCN cn c kh nng m rng, nng cp: thc hin ca DCN khng nn ph thuc vo kch c mng v. mt phng iu khin h tr mng c th c m rng khi trin khai mng mi Vic phi hp hot ng DCN mt phng iu khin l bc u tin hng n tch hp mt phng iu khin. Nhu cu cn c mt kin trc DCN mt phng iu khin chung v ngn xp giao thc mt phng iu khin ca cc mng khc nhau c th thng tin vi nhau.b. Tch ring mt phng iu khin v mt phng truyn tiMt phng iu khin GMPLS khng nn c bt c gi nh no v loi mi trng vt l s dng cho DCN ca n, m cn hm rng mt phng iu khin GMPLS v mt phng truyn ti ca n cn phi tch nhau ra, t nht cng v mt logic. iu ny nh hng n thit k mt phng iu khin GMPLS mt s kha cnh: DCN mt phng iu khin c th c mt topo vt l khc so vi mng truyn ti ca n Vic khm ph ti nguyn ln cn mt phng iu khin c th cn phi ph thuc cc c ch khc vi vic khm ph ln cn da trn DCN. Giao din iu khin v truyn ti c th c tch ring nhau. Do , hai mt phng iu khin gn nhau khng yu cu phi c mt knh iu khin trc tip min l chng trao i c vi nhau qua DCN. iu ny hm rng vic nh tuyn cc bn tin mt phng iu khin trong DCN mt phng iu khin c tch v mt logic so vi nh tuyn cc LSP trong mt phng truyn ti. Kh nng hot ng ca mt phng iu khin v mt phng truyn ti cn duy tr c lp nhau. iu ny yu cu tch bit gia cc thng bo v cc m trng thi cho mt phng iu khin v mt phng truyn ti. Trong trng hp s c mt phng iu khin (chng hn li knh thng tin hoc li thc th iu khin), cc hot ng kt ni LSP mch mi c th khng c chp nhn nhng cc kt ni tn ti s khng b hng. Cc bn tin bo hiu khng nht thit truyn dc theo ng s liu. V th mt s khi nim c bn trong MPLS cn nh ngha li trong mt phm vi ln hn. C bo hiu da trn IP v cc giao thc nh tuyn cn phi c tng cng ph hp vi s thay i ny.1.5.7 Bo hiu trong GMPLSBo hiu l mt trong cc chc nng quan trng ca mt phng iu khin GMPLS. Cc chc nng c bn bao gm: To LSP, loi b LSP, thay i LSP, thng bo li LSP, x l li LSP, khi phc LSP. to ra giao thc bo hiu mt phng iu khin GMPLS hiu qu v tin cy, cn tun th mt s nguyn tc c bn.1.5.7.1 Cc chc nng c bn Mt phng iu khin GMPLS gi s h tr cc mng IP v mng truyn ti. GMPLS cn tha hng nhng giao thc bo hiu ca MPLS, chng hn nh to LSP, xo LSP,... Ngoi ra, giao thc bo hiu GMPLS cn mt s yu cu khc. V mng truyn ti mang lng bng tn khng l v h tr nhiu ng dng, mt s c v mng nh t cp s gy ra hu qu rt nghim trng. Vic pht hin li v khi phc LSP nhanh tr thnh yu cu c bn i vi mng truyn ti. Tm li, bo hiu mt phng iu khin GMPLS cn h tr: To LSP Xo LSP Thay i LSP Khi phc LSP X l loi b LSPa. To LSPHot ng to LSP bt u khi nt GMPLS u vo nhn mt yu cu LSP. Nt ny thng thc hin cc qu trnh cp php chnh gm iu khin tip nhn v kim tra ti nguyn. Nu cp php c xc nhn, nt GMPLS vo cn chn mt ng cho LSP vi cc thng tin c th v bt u qu trnh. Mt bn tin to LSP s chuyn t nt vo v di chuyn dc theo ng c chn. Trong mng truyn ti, mt bn tin xc nhn c yu cu t nt ra n nt vo. i vi LSP hai hng, bn tin bt tay ba hng s cung cp trong giao thc bo hiu thc hin c hai pha ca qu trnh thit lp LSP. Trong khi to LSP, ti nguyn c th c cp pht trc hoc sau khi ton b ng c ng k trc.

b. Xo LSP Khi LSP khng cn na hoc LSP m mng loi b, ti nguyn do cc LSP ny s hu cn c gii phng. Mt bn tin yu cu xo c to ra trong giao thc bo hiu. Hot ng xo c th bt u t mt nt GMPLS bt k, bo hiu xo cn c thit k sao cho x l c ba trng hp.Trong mng truyn ti, LSP c xo tng phn s gy phc tp. Trong khi xo LSP, mt nt GMPLS li dc theo LSP s dn n khng hon thnh c vic xo LSP. Mt bn tin xc nhn xo do nt xut xo yu cu m bo hon tt th tc xo. Trong hot ng xo, c th xut hin cc tnh trng chy ua gia bn tin yu cu xo v vic cp pht li ti nguyn. Da vo tnh trng ny, cc cnh bo c th xut hin ti cc nt dc theo LSP. h tr mt mi trng nh vy, cn mt c ch cho php hoc khng cc cnh bo kt hp vi LSP trc cp pht li ti nguyn.C hai gii php trnh tnh trng ny: Cc nt dc theo ng s thng bo c cu LSP, gn nh tn hiu ASP SONET. Cc nt dc theo ng s c khai bo nh mt phn trong bn tin xo. Sau khi xc nhn, chng s cp pht li ti nguyn.

c. Thay i LSPMt LSP c th yu cu c thay i cc c tnh ca n, chng hn nh bng tn. Yu cu c bn ca vic thay i LSP c gi l thay i trc khi khng p ng c (made - before break). Giao thc bo hiu cn c thit k h tr chc nng ny. Mt gii php thc hin c c th bao hm vic chia s ti nguyn gia LSP c v LSP mi.1.5.7.2 H tr phc hiPhc hi nhanh cc s c mng l mt kha cnh rt quan trng ca mng truyn ti hin ti v tng lai. Cc nh cung cp mng truyn ti yu cu kh nng phc hi nhanh m bo tin cy v tnh sn sng cho cc kt ni ca khch hng. Vic chn chnh sch phc hi cn c s cn bng gia vic s dng ti nguyn mng v thi gian gin on dch v. Cc s phc hi khc nhau hot ng vi s cn bng khc nhau gia cc yu cu dung lng d v thi gian ngt dch v. Lc phc hi GMPLS cn bao gm t nht l bo v tuyn, bo v ng ring, khi phc ng dng chung, nh tuyn li ng.1.5.7.3 H tr x l loi trCc mc khc nhau ca vic loi tr c th xut hin trong mng GMPLS c mt phng s liu v mt phng iu khin. Mt s loi tr cn xem xt trong thit k bo hiu GMPLS gm: Nt vo, nt trung gian, nt ra c th t chi vic to LSP. Nu ti nguyn c cp pht trc khi xc nhn LSP, vic t chi to thnh LSP c th phi cp pht li nhng ti nguyn ny. Mt nt pht hin s c ca th tc phc hi, vic loi tr ny s dn n phc hi tuyn LSP. Nu mt qu trnh phc hi LSP li, v cc l do nh mt phng iu khin GMPLS dc theo ng hi phc c s c hoc thiu ti nguyn dc theo ng hi phc. iu ny c th dn n cp pht li cc ti nguyn c cp pht tng phn cho LSP hi phc ny ngay nhng ti nguyn ny c dng cho vic khi to v khi phc cc LSP khc.Mt qu trnh xo LSP b li do li mt phng iu khin dc theo ng LSP.

1.5.7.4 Phi hp bo hiuTt c cc bn tin bo hiu khng tn ti c lp. Nhng chc nng v hot ng cn c phi hp vi nhau. Nu khng mt bn tin bo hiu c th lm cho mt bn tin bo hiu khc khng c x l ng.Bo hiu GMPLS cn phn bit gia thit lp ng hot ng v thit lp ng phc hi. Bo hiu MPLS c th thit lp 2 LSP tch ring lin kt/nt cng lc cho mi yu cu. Lu lng s liu c th c chia vo cc LSP hoc chuyn vo mt ng. Mt ng khc c s dng ch khi ng u tin b li. iu ny c tnh kh thi v LSP th hai khng chim bng tn nu khng c s liu pht trong ng ny. Trong mng truyn ti, vn li khc. s dng hiu qu bng tn, ng hi phc c th cn c thit lp sau khi ng dch v b li. ng hi phc c tnh ton trc hoc ngay lc . Mt im khc na gia thit lp ng hot ng v ng phc hi l vn tr thi gian. C th l thit lp ng hi phc yu cu tr thi gian lu hn.GMPLS cn c kh nng h tr c cc LSP n hng v LSP hai hng. Cc mng vin thng truyn thng in hnh l hai hng. Cc nghin cu gn y cho thy lu lng s liu trn Internet l khng i xng. Cc LSP n hng cho lu lng s liu l hp l hn. Mc d cc dch v dng c LSP n hng v a hng hin nay cha xc nh, giao thc bo hiu GMPLS cn phi chun b h tr c cc ng dng trong cng mt cu trc. iu ny to ra s tranh ginh nhau gia LSP n hng v LSP hai hng cng nh gia cc LSP hai hng t hai hng khc nhau.Hot ng xo LSP v qu trnh hi phc nhanh LSP c th phi hp tt vi nhau. Mt phng iu khin GMPLS l mt h thng phn tn. Hot ng ca mt nt s khng lm cho nt khc kh hiu.Mt phng iu khin GMPLS c th xy ra s c. Sau khi khi phc, giao thc bo hiu s thit k mt s c ch ng b cc c s thng tin qun l LSP v cc ti nguyn lin kt vi ti nguyn ln cn ca chng. Trong thi gian mt phng iu khin b li, LSP c th b xo b v ti nguyn lin kt c cp nht. Hai gii php thc hin c th l: S dng bn tin thm vn ln cn ng b ho c s thng tin ca n. S dng bn tin lm mi LSP ng b c s thng tin ca n.

1.5.8 Cc li ch ca GMPLSGMPLS mang li nhiu li ch ni bt, th hin c th trong cc vn sau: Thit k lu lng qua lp Tch hp vic khi phc v bo v Cung cp dch v nhanh chng Tng li nhun Cho php thc hin cc qu tr.nh linh hot, t ng v c tnh mm do cao trong mi trng mng quang tnh Cc tiu chun m: GMPLS c th hot ng trong mi trng a nh cung cp thit b, a lp v a nh khai thc. Cc mng ng nht: Cc mng quang v mng s liu c th c gim st, qun l, bo dng nh mt mng n s dng mt h thng qun l n. X l cc s c v bo dng: Nh cung cp dch v nhanh chng c lp v x l cc s c v mng nh cc cnh bo t ng ca h thng qun l cng nh cc s c gia mng truyn ti v mng s liu1.5.9 Cc vn cn tn ti ca GMPLSBn cnh nhng u im vt tri ca GMPLS mang li so vi cc phng thc iu khin hin ti, n cng bc l mt s vn cn dc b sung nh: An ton: nh tuyn IP truyn thng kim tra ni dng header ca gi nhn c xc nh trm k tip. Bc ny tuy mt thi gian nhng cho php thit lp c cc firewall, v cc thng tin cn thit trong tiu gi nh a ch ch, a ch ngun l khng i trong c qu trnh. Ngc li, cc nhn MPLS/GMPLS c s dng thc y qu trnh pht chuyn v ch c gi tr trong ni b, chng hn nhn c hiu v s dng ch trong cc thit b GMPLS. Nhng nhn ny khng th c dng iu khin truy nhp hoc cho mc ch bo mt mng. Ch mt cch thit lp bo mt trong mng GMPLS l bt buc bo mt truy nhp trong thi gian thit lp kt ni, nh cc mng hng kt ni khc. Vn phi hp hot ng: S thnh cng ca GMPLS ph thuc vo kh nng thng tin vi nhiu c s h tng mng hin ti nh ATM, FR. Phi hp hot ng vi mng ATM v FR s cho php truyn ti cc thng tin mt phng s liu v iu khin c trao i gia hai mng ging nhau (v d hai mng ATM) thng qua mt mng khc (v d GMPLS). Vic thc hin chc nng phi hp hot ng gia nhng mng ny gp mt s vn : Phi hp mt phng iu khin l rt phc tp v mi mng s dng mt tp cc giao thc khc nhau (v d nh tuyn, giao din mng n mng ring (PNNI) trong mng ATM so vi giao din OSPF-TE trong mng GMPLS) Chuyn mch GMPLS c th da trn gi, TDM, bc sng, si, bng tn. iu ny to ra mt vi kt hp trong vic phi hp mt phng s liu gia mng GMPLS v mng ATM hoc mng FR. Mt s din n cng nghip hin ang thc hin mt s vn c th v phi hp hot ng gia cc mng (v d MPLS Forum, ATM Forum, ...). Cc gii php thc t phi gip nh qun l mng qun l c mng MPLS v mng truyn thng. Nhng gii php ny hin ti vn cha c xc nh. S cn bng mng: Khi cc ti nguyn mi c g b hoc thm vo mng GMPLS, tp cc thng tin iu khin c trao i ln hn i vi mng IP truyn thng. GMPLS s dng m hnh thit k lu lng bao gm gii thiu mt s tham s lu lng, kt hp vi cc lin kt s liu, nh tuyn da trn cc rng buc thc hin, LSP,...Vn ny tuy cha c kim nghim tuy nhin v mt l thuyt mng MPLS/GMPLS s cn thi gian tng quan ln hn so vi mt mng IP truyn thng khi mng b s c. H thng qun l mng: Tham s quan trng nht trong vic qun l mt mng IP truyn thng, v d mng Internet l a ch n. Ngc li, h thng qun l mng GMPLS cn lu vt ca hng nghn (thm ch hng triu) LSP cho trng thi hot ng ca chng, cc ng nh tuyn, thit k lu lng,... iu ny dn n h thng qun l mng GMPLS phc tp hn so vi mng Internet truyn thng. 1.6. TM TT CHNG 1Vic s dng nhn ngn, n gin lm cho vic chuyn tip gi tin mt cch nhanh chng, hiu qu. K thut chuyn mch nhn a giao thc MPLS kt hp nhng c im ni bt ca chuyn mch lp 2 v lp 3 mt cch tt nht.GMPLS vi nhng ci tin v t c nhiu thun li hn so vi MPLS. Nh vy GMPLS s l mt cng ngh ng c quan tm cho vic truyn dn lu lng ngy cng cao ca th gii hin nay. GMPLS khng ch h tr cho chuyn mch gi nh MPLS, GMPLS cn c th gn nhn cho bc sng, khe thi gian do , c p dng vo trong mng truyn dn quang ng trc WDM rt tt.GMPLS l mt cng ngh mi, v ang c nghin cu c th p dng c trong thc t. Mng MPLS, v c bit l WDM c trin khai trn thc t, to ra mt h c s c th ng dng GMPLS khi m lu lng thng tin ngy cng tng vt. y l mt hng nghin cu rt hay trong giai on ny.

Chng 1 Tng quan v cng ngh chuyn mch nhn a giao thc MPLS v GMPLS

CHNG 2GII THIU BI TON NH TUYN V GN BC SNGTRONG MNG QUANG

2.1. GII THIUQua mt vi nm gn y, DWDM (Dense Wavelenght Division MultIPlexing) tr thnh mt cng ngh ch o cho mng quang th h su. Vic s dng DWDM a knh c phn bit bi cc bc sng khc nhau c th c truyn trn mt si quang, vi mi knh hot ng tc nh ca n. Mi bc sng ca mi si ca mt tuyn lin kt l mt knh con hon ton c lp vi cc bc sng khc trn cng mt si. Mt khi nim nh vy thng c gi l mng quang v mng quang thng minh ION, l ni lp quang vt l tr nn nhn bit c cc kt ni bng vic xc nh cc bc sng ca chng. Mt cng ngh in hnh ca mng DWDM v cc knh lin kt khc ca n c bit n nh cc bc sng c cho trn hnh 2.1.

Hnh 2.1. Mng DWDM nh tuyn bc sng [13]Trong mng nh tuyn, ngi s dng ny thng tin vi ngi s dng khc qua knh ton quang, cc knh ny c xem nh l cc lung quang. Mt lung quang c s dng h tr mt kt ni trong mng inh tuyn bc sng v c th lin kt cc si quang. Trong trng hp khng s dng b chuyn i, mt lung quang chim cng bc sng trn tt c cc lin kt si m n i qua. c tnh ny gi l iu kin rng buc bc sng lin tc. Gi s rng mi chuyn mch quang c ni ti mt nt truy nhp nh l mt nt. Khi a ra mt tp kt ni, bi ton thit lp cc lung quang bng nh tuyn v gn bc sng mi kt ni c gi l bi ton nh tuyn v gn bc sng (RWA- Routing and Wavelength Assignment).2.2. CC LOI BI TON RWAThng thng, c hai loi lu lng mng l tnh hoc ng. Do vy bi ton RWA gm hai loi tnh v ng. iu ny dn n hai kiu thit lp lung quang: Bi ton thit lp lung quang tnh v thit lp lung quang ng.2.2.1 Thit lp lung quang tnh (SLE)Trong bi ton ny tt c cc yu cu kt ni c bit trc v khng thay i. l yu cu cho vic thit lp mt tp hp cc ng quang c a ra u tin. Cc ng quang ny khng b gii phng ngay khi chng c thit lp. Cc ng quang c gi s l cc lung quang, l rng buc bc sng lin tc. Bi ton ti u l ti thiu s bc sng cho mt cu hnh mng nht nh, s si quang, v tp hp cc ng quang yu cu.2.2.2 Thit lp lung quang ng (DLE)Trong bi ton ny tt c cc yu cu kt ni n mt cch ng v lung quang c gii phng sau mt thi gian hn nh. Bi ton ti u l ti thiu xc sut tc nghn yu cu cho mt s bc sng nht nh v hoc ti thiu gi thnh mng.Bi ton thit lp lung quang tnh c th t c nhiu hn vi cng ngh hin nay v s l gii php tng lai gn trong mng quang thng minh ION. Nhng khi lu lng trong mng li s tr nn ng hn th thit lp lung quang ng s phi c thc hin trong mng ION. Do vy n ny s tp trung ch yu vo vic gii quyt bi ton DLE.2.3. CC PHNG PHP GII BI TONBi ton RWA lin quan n cc phn khc nhau, thng c gii quyt ring bit n gin ho bi ton. Vi bi ton nh tuyn th c ba phng php nh tuyn c bn: nh tuyn c nh, nh tuyn thay th c nh v nh tuyn thch nghi.Trong nh tuyn c nh, ch c mt tuyn c nh (v d nh ng ngn nht) gia cp nt ngun v ch.Trong nh tuyn thay th c nh, mi nt duy tr mt bng nh tuyn m cha mt danh sch cc tuyn c nh c yu cu ti mi nt ch. V d nh, cc tuyn ny c th bao gm tuyn ngn nht u tin, tuyn ngn nht th hai, tuyn ngn nht th ba vv.. Tuyn thc t cho mt yu cu kt ni ch c th c chn la t tp cc tuyn ny.Trong nh tuyn thch nghi, nh tuyn da trn bc sng c th s dng hin c trn mi tuyn lin kt. Bt k tuyn kh thi no t nt ngun ti nt ch c th ng c nh tuyn thc t cho mt yu cu kt ni. Vic la chn tuyn ph thuc vo chnh sch mng c s dng nh ng u tin chi ph ngn nht hoc ng u tin tc nghn t nht.Ni chung, nh tuyn c nh l n gin nht trong khi nh tuyn thch nghi mang li c tnh tt nht. nh tuyn thay th c nh em li s tho hip gia s phc tp v c tnh mng.Bi ton gn bc sng l mt phn khc ca bi ton RWA. Ni chung, n d dng hn nhiu so vi bi ton nh tuyn, nhng cng ph thuc vo kt qu ca gii php nh tuyn. Tuy nhin n thng nh hng ti kt qu hiu sut ca gii thut RWA.2.4. C S L THUYT 2.4.1. Gii thiu l thuyt th

Trong l thuyt th, cu hnh mng c th c biu din nh th G (V, E), V biu th tp cc nh (cc nt mng) v E l tp hp cc bin (Cc tuyn lin kt mng). V th hin s nt trong th v thng c gi l bin ca th. Mi tuyn lin kt (i, j) E c th c kt hp vi mt hm trng W m biu din bng mt phng php no xc nh chi ph s dng tuyn lin kt (i, j). Bc ca nt iV l s nt ln cn ca nt i. ti ch xt bi ton ng i ngn nht trong th. Cho th G(V, E) bi ton t ra l tm ng i trong th m ti thiu tng trng lng ca tt c cc tuyn lin kt din ra gia hai nh. L thuyt th cung cp nhiu cch gii quyt bi ton . Gii thut ph bin nht l gii thut Dijkstra v Bellman- Ford. Di y ch gii thiu v gii thut Dijkstra.2.4.2. Gii thut DIJKSTRA Gii thut Dijkstra c gii thiu vo nm 1959 cung cp mt gii thut hiu qu nht cho vic gii quyt bi ton ng i ngn nht. N tm ng i ngn nht t mt nh ngun s cho ti mi nh d trong V bng vic trin khai cc ng i theo th t di ng i tng dn. Mi nt c dn nhn bng khong cch ca n t nt ngun dc theo ng c xem l tt nht. u tin khng ng i no c bit n do vy tt c cc nt c dn nhn l . Khi gii thut tin hnh v cc ng i c tm ra th cc nhn c th thay i tng ng vi cc ng i tt hn. Nhn c th l thm d hoc c nh. Ban u tt c cc nhn l thm d. Khi n c khm ph ra m nhn th hin ng i ngn nht c th t ngun ti nt th n oc to c nh v khng bao gi oc thay i sau .2.5. BI TON RWA TRONG THIT LP LUNG QUANG TNH (SLE)Bi ton SLE c th c gii nh bi ton quy hoch tuyn tnh nguyn, n l bi ton NP y . gii bi ton ny d dng hn, bi ton SLE c th chia thnh 2 bi ton nh 1. nh tuyn2. Gn bc sngMi bi ton ny gii theo nhng cch khc nhau. Mt s gii thut gn ng c dng gii bi ton SLE cho cc ng mng ln v thut ton t mu th c dng gn bc sng ti cc lung quang mt khi cc lung quang c nh tuyn ng.i tng ca hm mc tiu l ti thiu s bc sng cn thit thit lp mt tp hp cc bc sng no cho mt cu hnh vt l a ra. Bi ton thay th bi ton ti thiu s bc sng trong mng l bi ton vi mc tiu l cc i s cc kt ni c th c thit lp (ti thiu s tc nghn) cho mt s bc sng v cc yu cu kt ni a ra.Bi ton SLE vi iu kin rng buc bc sng lin tc c th p dng nh quy hoch lp tuyn tnh nguyn ILP (Integer Linear Program) trong hm mc tiu l ti thiu lu lng trn mi lin kt, ln lt n tng ng vi ti thiu s lung quang qua tng lin kt ring bit.Thut ton heuristic cho bi ton gn bc sng cho mt tp lung quang tnh thng thng lin quan n trnh t bc sng, v gn cng bc sng cho cng nhiu lung quang cng tt trc khi chuyn sang bc sng tip theo. Hn na tp cc lung quang c th c xp theo th t theo di, cc bc sng c gn cho cc lung quang di hn trc khi cc bc sng c gn cho lung quang ngn hn. Tt c cc phng php heuristic chim rt nhiu CPU v chng l cc gii php khng thit thc cho thc thi bi tnh phc tp thng thng ca n.Tiu chun xc nh RWA l ti thiu s cc bc sng cho mt cu hnh mng cho, s si quang, v tp cc ng quang yu cu.Mc d tm ra cc gii php gii quyt bi ton SLE nhng chng hu nh u da vo nhng phng php phc tp v do vy khng thc s ph hp cho nhng thc thi thc t. Hn na, vn SLE khng quan tm n lu lng ng. iu ny c th ph hp cho mng ng trc ngy nay; nhng trong tng lai rt gn, vic qun l lung quang t ng p ng cc nhu cu cho lu lng ng phi c cung cp. y l mc tiu ca cc bi ton DLE m c gii thiu sau y.2.6. BI TON RWA TRONG THIT LP LUNG QUANG NG (DLE)Khi cc lung quang c thit lp v loi b mt cch ng th cc quyt nh RWA phi c thc hin khi cc yu cu kt ni n mng. Vi mt yu cu kt ni nht nh c th ti nguyn mng khng thit lp mt lung quang, trong trng hp yu cu kt ni s b nghn. Vic kt ni cng c th b nghn nu khng c bc sng chung c th s dng trn tt c cc tuyn dc theo tuyn c chn (rng buc bc sng lin tc - WCC). Do vy, mc tiu trong trng hp lu lng ng l chn tuyn v bc sng m ti a kh nng thit lp kt ni cho, trong khi cng lc n lc ti thiu tc nghn cho cc kt ni tng lai.Cc thut ton RWA ng c c trng bi cc tham s v thc o in hnh ph hp vi mi trng lu lng ng. Trong cc yu cu n v i ra khi mng xut hin tng yu cu theo mt cch ngu nhin. Thc o c tnh c s dng thng ri vo mt trong ba loi sau y: S bc sng yu cu; Xc xut tc nghn kt ni (lu lng a vo) c tnh bng t s gia nhng kt ni b tc nghn trn tng s cc kt ni n hoc i;- S lng ti nguyn si quang c nm gi ti cc nt nh tuyn (chi ph si quang). Ging vi trng hp lung quang tnh, bi ton RWA ng cng c th chia thnh bi ton nh tuyn v bi ton gn bc sng. Phng php gii quyt bi ton nh tuyn c th phn loi theo hoc c nh hoc thch nghi, v theo s dng thng tin trng thi mng hoc tng th cc b.Mt s phng php heuristic in hnh xut cho bi ton ny nh sau: 2.6.1. Bi ton nh tuynA. nh tuyn c nhCch tip cn n gin nh tuyn mt kt ni l lun la chn mt tuyn c nh nh nhau cho mt cp ngun ch. Mt v d in hnh ca cch tip cn ny l nh tuyn ng ngn nht c nh. ng ngn nht tnh cho mi cp ngun ch c tnh trc (offline) s dng thut ton ng ngn nht chun nh Dijkstra hoc Bell Ford. Do nt mng khng cn thit lu gi ton b trng thi mng. Bt k kt ni no gia cp cc nt ring c thit lp s dng tuyn c xc nh trc. Trong hnh 2.2 ng ngn nht c nh minh ho t nt 0 n nt 2. Cch tip cn ny l nu ti nguyn (bc sng) dc theo cc ng tc nghn, n c th dn n cc xc xut tc nghn cao trong trng hp lu lng ng hoc dn n mt s lng ln cc bc sng ang s dng trong mng trong trng hp lu lng tnh. nh tuyn c nh cng khng th iu khin cc tnh hung sai hng trong mt hay nhiu cc lin kt no trong mng hng. iu khin cc sai hng lin kt, vic t chc nh tuyn hoc phi xem xt cc ng la chn ti ch hoc phi c kh nng tm thy mt tuyn ng. Trong hnh 2.2, mt yu cu kt ni t nt 0 n nt 2 s b kho nu mt bc sng chung khng th s dng trn c hai lin kt trong tuyn c nh

HNH 2.2: ng ngn nht c nhB. nh tuyn thay th c nhMt cch tip cn xem xt nh tuyn l nh tuyn thay th c nh. Trong nh tuyn thay th c nh, mi nt trong mng c yu cu duy tr mt bng nh tuyn cha danh sch ch th ca mt s cc tuyn c nh ti mi nt ch. V d, nhng nt ny c th bao gm tuyn u tin ngn nht, tuyn th hai ngn nht, tuyn th ba ngn nht .. Mt tuyn chnh gia mt nt ngun s v mt nt ch d c nh ra l tuyn u tin trong danh sch cc tuyn ti nt d trong bng nh tuyn ti nt s. Mt tuyn thay th gia nt s v nt d l bt k tuyn no m n khng dng chung bt k lin kt no (l lin kt c lp) vi tuyn u tin trong bng nh tuyn ti nt s. Thut ng tuyn thay th cng thc hin m t tt c cc tuyn (bao gm c tuyn chnh) t mt nt ngun ti mt nt ch. Hnh 2.3 m t tuyn kt ni nt chnh (ng lin) t nt 0 n nt 2, v tuyn thay th (ng chm) t nt 0 n nt 2.

Hnh 2.3. Tuyn chnh (nt lin) v tuyn thay th (nt chm)Khi mt kt ni yu cu n, nt ngun th thit lp kt ni lin tip trn mi tuyn t bng nh tuyn n khi mt tuyn ni mi bc sng gn hp l tm thy. Nu khng c tuyn no c th dng c tm thy t danh sch cc tuyn thay th th yu cu kt ni b kho hoc mt. Trong hu ht cc trng hp, cc bng nh tuyn ti mi nt c ch th bng s cc on lin kt si quang (chng) ti ch. Nh vy ng ngn nht ti ch l ng u tin trong bng nh tuyn. Khi c cc rng buc v khong cch gia cc tuyn khc nhau, mt tuyn c th c la chn ngu nhin. nh tuyn thay th c nh cung cp iu khin d dng cho thit lp v gii phng cc lung quang v n cng c th c s dng vi mt s mc li chp nhn c trn cc lin kt hngC. nh tuyn thch nghi da trn thng tin tng th Phng php nh tuyn thch nghi tng kh nng xy ra thit lp kt ni bng vic a vo tnh ton thng tin trng thi mng. Vi trng hp thng tin tng th l c th s dng th cc quyt nh nh tuyn c th thc hin vi thng tin y v mt cc bc sng c th s dng trn mi tuyn lin kt trong mng. nh tuyn thch nghi da trn thng tin tng th c th thc hin hoc bng phng php tp trung hoc bng phng php phn tn. C cc loi nh tuyn thch nghi sau y:C.1. nh tuyn ng thay th c nh nh tuyn ng thay th da vo tp cc tuyn c nh c quyt nh trc gia nt ngun v nt ch. Khi yu cu kt ni n th mt tuyn c la chn t tp cc tuyn quyt nh trc, v lung quang c thit lp trn tuyn ny. Tiu chun la chn tuyn thng da trn hoc di tuyn hoc tc nghn trn tuyn.+ La chn tuyn da trn diV d ca gii thut nh tuyn da trn di l gii thut K ng ngn nht, trong K ng ngn nht c duy tr cho mi cp ngun ch, v cc ng la chn theo th t chiu di t ngn nht ti di nht. Kt ni ngn nht c th trn ng ngn nht. Nu ti nguyn khng th s dng trn ng ny th ng ngn nht tip theo s c th.+ nh tuyn da trn tc nghn ng i Phng php la chn tuyn da trn tc nghn xc nh ti nguyn c th s dng trn mi ng thay th, v chn la ng m trn s lng ti nguyn ln nht c th c s dng.La chn tuyn ng ngn nht chi ph ti nguyn mng t hn c th dn ti ti trng cao trn mt s tuyn lin kt trong mng. Trong khi la chn ng vi tc nghn t nht dn ti cc ng di hn, nhng phn b ti u hn qua mng.C.2. nh tuyn khng rng bucPhng php nh tuyn thich nghi khc m s dng thng tin tng th l nh tuyn khng rng buc. nh tuyn ny xem xt tt c cc ng c th gia mt nt ngun v mt nt ch. la chn mt tuyn ti u, mt chi ph c gn cho mi ng lin kt trong mng da trn thng tin trng thi mng hin ti, nh bc sng c th s dng c trn cc tuyn lin kt. Gii thut nh tuyn chi ph t nht sau c thc hin tm tuyn chi ph t nht. Bt c khi no kt ni c thit lp hoc gii phng, th thng tin trng thi mng phi c cp nht.Hai v d v nh tuyn khng rng buc l nh tuyn trng thi lin kt v nh tuyn vect khong cch. + inh tuyn trng thi lin kit Trong phng php nh tuyn trng thi lin kt phn tn, mi nt trong mng phi duy tr y thng tin trng thi mng. Mi nt sau c th tm tuyn cho yu cu kt ni bng phng php phn tn. Bt c khi no trng thi ca mng thay i th tt c cc nt phi c cung cp thng tin. Do , vic thit lp hoc gii phng mt lung quang trong mng c th dn ti qung b thng tin cp nht ti tt c cc nt trong mng. Nhu cu qung b bn tin cp nht c th dn n tng chi ph iu khin ng k. Hn na, mt nt c th c thng tin b li thi lm cho nt thc hin quyt nh nh tuyn da trn thng tin ny khng ng.Mt s khc phc c thc hin nng cao cc gii thut tuyn chung ngn nht bng vic s dng inh tuyn trng thi lin kt. T ch ra rng thc o da trn s dng chng trung gian thp nht v tng hp ca tng s bc sng v bc sng c th s dng cho kt qu xc xut tc nghn t nht.Sau y gii thiu cc thc o hm trng c s dng trong mng WDM c th c s dng bng gii thut Dijkstra.

Gi l s bc sng c th s dng trn tuyn lin kt v l tng s cc bc sng c th trn tuyn lin kt . Khi hm trng da trn tng s bc sng c th s dng (Total Wavelength and Avaiable TWA) c m t nh sau:

Gi W l hm trng ca tuyn . Trong TWA, W c nh ngha nh sau:

W= - log E (2.1)Gi P l xc xut m mt bc sng c s dng trn mt tuyn lin kt. Nu

v bit, p c th c tnh:

P=1- (2.2)

Khi xc sut m tt c cc bc sng s c s dng ti mt thi im trong tng lai c th c vit l p. Khi xc xut m t nht mt bc sng c th s dng c trn mt lin kt trong tng lai c a ra bng (1 - P) . Vi mt tuyn bao gm nhiu lin kt, mc tiu l ti a kh nng m mt bc sng c th s dng trong tng lai, tc l cc i gi tr (1 - P) ca tt c cc lin kt c th to thnh tuyn. n s dng log (1 - P) nh mt hm trng tng ng v thc hin ti thiu gi tr ny. y l mt hm trng ng cho bc sng lun thay i.+ nh tuyn vect khong cch Phng php vc t khong cch c th nh tuyn vi thng tin tng th. Phng php ny khng i hi mi nt duy tr y thng tin trng thi lin kt mi nt, nhng thay v mi nt lu gi mt bng chuyn tip dnh ring cho mi ch v mi bc sng, chng tip theo ti ch v khong cch ti ch. Phng php ny da vo gii thut Bellman- Ford phn tn duy tr cc bng nh tuyn. Ging vi nh tuyn trng thi lin kt, bi ton cng yu cu cc nt cp nht thng tin bng nh tuyn ca chng bt c khi no mt kt ni c thit lp hoc gii phng. Vic cp nht ny c thc hin bng vic mi nt gi mt bn tin cp nht nh tuyn ti cc nt ln cn chng theo chu k hoc bt c khi no trng thi cc tuyn lin kt li ra ca nt thay i. Mc d mi nt duy tr thng tin t hn nh tuyn trng thi lin kt v cp nht khng qung b ti tt c cc nt nhng bi ton ny c th vn chu mc chi ph iu khin cao.Gii thut vect cng rt hay ch, bng mt s cch n c th thc hin nh tuyn rng buc da trn s chng v cc loi thc o khc nhau. Thc vy, cc gii thut nh tuyn tiu chun thng ti u mt mc tiu, tc l chng c th ti thiu s chng trung gian, hoc ti thiu loi thc o khc no nhng khng th l c hai. Ti u mc tiu kp l nhim v phc tp hn v ni chung n l mt bi ton kh gii.Gii thut ng i ngn nht Bellman-Ford c dng cho vic tnh ng i ca mt thc o ti thiu cho tt c cc chng trung gian. y l mt tnh cht ca gii thut Bellman Ford m h ln lp li ca n, n xc nh ng ti u gia ngun v ch, gia cc ng i hu ht h chng. Tuy nhin, bi v gii thut Bellman-Ford tin hnh bng vic tng chng s chng trung gian nn n cn cung cp cho chng trung gian ri mt ng i nh mt tiu chun ti u th hai. y c th l mt tnh nng c bit th v nu mc tiu l tm ng ngn nht (vi mt thc o c th) trong khi vn tm mt ng tng i ngn, l ng cng ti thiu chng trung gian.+ So snh gia nh tuyn vect khong cch v nh tuynTrng thi lin kt trong bi ton RWAnh tuyn trng thi lin kt v vct khong cch l hai kh nng c th x l ton b tin tc v mng. Tuy nhin, vic la chn c hai gii thut gy ra cc ch rt khc nhau khi xem xt vn RWA. Hiu sut ca hai phng php cho vic thit lp lung quang ng th trng thi lin kt lm tt hn vi ti trng thp. nh tuyn phn tn cho xc xut tc nghn thp hn vi ti trng cao.Tuy nhin, khuyt im c bn ca gii thut vect khong cch l ch chng khng ph hp nhiu bng gii thut lin kt khi xem xt vn x l lu lng. c bit, u im chnh ca gii thut trng thi lin kt l mi nt c mt tin tc tng th v mng. iu ny lm cho n d dng tm cc tuyn r rng t mt nt ngun ti mt nt ch, do vy tng xc xut mc li hn cho mng. V d c th tng kh nng khi phc khi cc nt y tin v mng.Mc d bi ton nh tuyn da trn tin tc tng th phi gii quyt nhim v duy tr mt s lng ln thng tin trng thi ang thay i lin tip, nhng bi ton ny thng thc hin cc quyt nh tuyn ti u nht nu thng tin trng thi l mi nht. Do vy, bi ton da trn thng tin tng th c th rt ph hp cho cc mng m trong lung quang l kh tnh v khng thay i nhiu theo thi gian. D. nh tuyn thch nghi da trn thng tin cc b u im ca thng tin cc b l cc nt khng phi duy tr mt s lng ln thng tin trng thi; tuy nhin, cc quyt inh nh tuyn c khuynh hng km ti u hn so vi trng hp thng tin tng th. Hai v d v bi ton nh tuyn thch nghi da trn thng tin cc b l nh tuyn thay th vi thng tin cc b v nh tuyn lch.D.1. nh tuyn thay th da trn thng tin cc b Trong khi cc bi ton nh tuyn thay th thng da trn thng tin tng th th khc vi hin nay ch dng thng tin cc b. Trong bi ton nh tuyn thay th tc nghn t nht, vic la chn mt tuyn c xc nh bi bc sng c th s dng dc theo tuyn thay th. Hai bi ton khc nhau c xem xt: Trng hp trong thng tin bc sng c th s dng c bit n dc theo ton b tuyn, v trng hp ch c thng tin bc sng l c th s dng c bit n dc theo ton b tuyn, v trng hp trong ch c thng tin cc b l c th s dng.+ Nhn bit bc sng u cui - u cui

Trong phng php u tin, thc th thc hin nh tuyn nhn thy thng tin bc sng c th s dng cho tt c cc tuyn lin kt trong cc ng thay th. Trong trng hp ny, tuyn c chn l tuyn c bc sng ln nht c th s dng dc theo ton b cc tuyn lin kt trong ng i ca n. V d nh, trong hnh 2.4, nu hai tuyn thay th t nt ngun A ti nt ch D c xem xt vi cc bc sng c th s dng nh c ch trn mi tuyn lin kt, th hai bc sng ( v ) l c th s dng dc theo ton b di ca tuyn 1, trong khi ch mt bc sng ( ) l c th s dng dc ton b chiu di tuyn 2; do vy tuyn 1 s c la chn.

Hnh 2.4: nh tuyn thay th+ Nhn bit bc sng tng phn

Phong n da trn thng tin cc b l kt hp thng tin bc sng c th s dng ch dc k chng ngn nht ca mi ng. Tuyn sau c la chn da trn loi ng b tc nghn t nht dc theo k chng ngn nht ca n. Trong hnh 2.4, nu k =2 th tuyn 2 s c la chn, do n c ba bc sng c th s dng trn hai tuyn lin kt ngn nht ( , , v ), trong khi tuyn 1 ch c hai bc sng c th s dng trn hai tuyn lin kt ngn nht ( v ).Mc d thng tin cc b c th cung cp mt s nh gi tt v tc nghn dc theo ng i nhng n khng m bo bc sng c trng l c th s dng dc ton b ng i; do vy, c th sau khi chn la mt tuyn, mt kt ni vn s b tc nghn do thiu cc bc sng c th s dng.D.2. nh tuyn lchMt phng php khc cho nh tuyn thch nghi vi thng tin hn ch l nh tuyn lch, hoc nh tuyn lin kt thay th. Bi ton nh tuyn ny chn la t cc tuyn thay th trn c s theo chng hn l chn la t cc tuyn trn c s u cui - u cui. nh tuyn c thc hin bi mi nt duy tr mt bng nh tuyn th hin i din cho mi ch, mt hay nhiu tuyn lin kt li ra thay th tin ti ch . Cc tuyn lin kt li ra thay th ny c th ra c iu khin yu cu kt ni s u tin la chn cc tuyn lin kt no min l ti nguyn bc sng c th s dng trn cc tuyn lin kt ny.Khc vi bng nh tuyn tnh, mi nt s duy tr thng tin v trng thi ca bc sng s dng trn cc tuyn lin kt li ra ca chnh n. Khi la chn mt tuyn lin kt li ra cho nh tuyn, th quyt nh c th xc nh trn c s ng ngn nht hoc tc nghn t nht. + Bi ton nh tuyn lch vi ng i ngn nhtDi tiu chun ng i ngn nht, bi ton nh tuyn s c gng ngn nht la chn tuyn lin kt li ra m cho kt qu ng ngn nht ti ch. Nu khng c bc sng c th s dng trn tuyn lin kt th bi ton nh tuyn s c gng la chn mt tuyn lin kt li ra thay th m dn ti ng ngn nht tip theo ti ch. Bi ton nh tuyn tip tc bng phng php ny cho n khi ch n c tin ti hoc kt ni b tc nghn

Hnh 2.5 minh ho bi ton nh tuyn lch cho yu cu kt ni t nt A ti nt D. ng i ngn nht ngm nh trong v d ny l dc ng ABCD. Khi yu cu tin ti nt C, n khng th tip tc qua tuyn lin kt CD, do khng c bc sng chung c th s dng trn tuyn lin kt AB, BC, v CD. Do yu cu b lch ti nt F, n c th tip tc ti ch dc theo tuyn lin kt FD. Bc sng c la chn cho lung quang s l

Hnh 2.5: Bi ton nh lch ng i ngn nht+ Bi ton nh tuyn lch vi tc nghn t nhtTrong phng php nh tuyn lch tc nghn t nht th bi ton nh tuyn la chn trong s cc tuyn lin kt li ra thay th tuyn lin kt c s bc sng kh thi ln nht bao gm tp cc bc sng c th s dng trn tt c cc chng trc cng nh tuyn lin kt li ra tip theo.

Hnh 2.6: Bi ton nh tuyn lch vi tc nghn t nhtnh tuyn lch tc nghn t nht c minh ho trn hnh 2.6 cho mt kt ni t nt A ti nt D. Trn chng gn nht tuyn lin kt AB c la chn, do n c ba bc sng c th s dng, trong khi tuyn lin kt AE ch c hai bc sng c th s dng.

Khi yu cu kt ni n t nt B, n s nh tuyn ti nt E, do c ba bc sng kh thi ( , , v ) c th s dng trn tuyn lin kt BE, v ch c mt bc sng kh thi ( ) c th s dng trn tuyn lin kt BC.Phng php nh tuyn tc nghn t nht thng cho kt qu cc ng di hn phng php nh tuyn lch ng i ngn nht: tuy nhin, nh tuyn lch tc nghn t nht s cho php mt lung quang c nh tuyn li xung quang khu vc b tc nghn trong mng, ti cn bng hn khi quang qua mang.+ Cc vn nh tuyn lchMt s vn ny sinh khi thc hin bi ton nh tuyn lch. l vn vng lp, trong mt bn tin yu cu kt ni quay tr li nt m n n. Vic pht hin vng lp c th c gii quyt bng vic c bn tin yu cu kt ni duy tr mt vc t ng i cha danh sch cc nt n. Nu nt nhn bn tin yu cu kt ni ch ra rng bn tin n nt ny, th n lc kt ni s b chn li. Thay i vi vic duy tr vec t ng i l s dng trng thi gian sng, iu ny s ngn cn bn tin yu cu kt ni c vng lp v hn trong mng.Mt vn khc na c th xy ra l yu cu kt ni c th b lch mt lng ln thi gian dn n mt tuyn di v l cho lung quang. Gii php c th cho vn ny bao gm hn ch chiu di ti a ca cc chng trong mt lung quang, hoc gii hn lch m mt tuyn c th mc. Khi mt thng ip yu cu kt ni tin ti gii hn ca n vi s chng ti a hoc lnh ti a th n lc kt ni s b chn.2.6.2. Bi ton gn bc sngNi chung, nu c nhiu bc sng kh thi gia nt ngun v nt ch th gii thut gn bc sng c yu cu la chn bc sng cho lung quang nht nh. Vic la chn bc sng c th thc hin hoc sau khi tuyn c xc nh hoc sng sng vi vic tm kim tuyn. Cc bc sng c la chn bng cch ti thiu tc nghn cho chui cc kt ni.A. Thut ton gn bc sng theo th t bc sngMt v d v thut ton gn bc sng n gin nhng hiu qu l gn bc sng theo th t bc sng. Trong thut ton ny, cc bc sng c nh ch s v lung quang s c gng la chn bc sng vi ch s thp nht trc khi la chn bc sng vi mt ch s cao hn. Bng vic la chn bc sng theo phng php ny, cc kt ni hin ti s c gi thnh tng cc bc sng nh hn, loi b cc bc sng ln hn c th s dng cho cc lung quang.B. Thut ton gn bc sng ngu nhinPhong php khc la chn cc bc sng khc nhau l la chn n gin mt trong cc bc sng ngu nhin. Ni chung, thut ton gn bc sng theo th t bc sng s lm tt hn gn bc sng ngu nhin khi thng tin y v trng thi mng c th s dng. Tuy nhin, nu vic la chn bc sng c thc hin bng phng php phn tn ch vi thng tin hn ch v li thi th gn bc sng ngu nhin c th lm tt hn gn theo th t bc sng. L do cho c tnh ny l ch, trong phng php gn theo th t bc sng nu nhiu kt ni ang ng thi c gng thit lp mt lung quang th rt c th chng s la chn bc sng ging nhau dn n mt hoc nhiu kt ni b chn.C. Thut ton gn bc sng da trn bc sng s dng nhiu nht v t nhtThut ton gn bc sng n gin khc bao gm thut ton gn bc sng da trn bc sng s dng nhiu nht v t nht. Trong gn bc sng c s dng nhiu nht th bc sng c s dng nhiu trong phn cn li ca mng c la chn. Phng php ny n lc cung cp ti a bc sng s dng li trong mng. Phng php gn bc sng c s dng t nht n lc tri rng ti trng bng nhau qua tt c cc bc sng bng vic la chn bc sng c s dng t nht xuyn xut mng. C hai phng php gn bc sng da trn bc sng s dng t nht v s dng nhiu nht i hi tin tc tng th.2.6.3 Bo hiu v t trc ti nguyn thit lp lung quang th giao thc bo hiu c yu cu trao i thng tin iu khin gia cc nt v t trc ti nguyn dc ng i. Trong nhiu trng hp, giao thc bo hiu c kt hp cht ch vi cc gii thut RWA.Cc giao thc bo hiu v t trc c th c phn loi da trn hoc ti nguyn c t trc sng sng trn mi tuyn lin kt, c t trc theo chng dc ng i theo hng tin hoc c t trc theo chng dc ng ngc li. Cc gii thut cng s khc nhau ph thuc vo thng tin tng th c th s dng