ki thuat luu luong IP-WDM

8/7/2019 ki thuat luu luong IP-WDM

1/112

n tt nghip i hc Mc lc

MC LC

MC LC ......................................................................................................................I

THUT NG VIT TT ...........................................................................................IV

LI NI U ...............................................................................................................1CHNG I TNG QUAN V IP/WDM .....................................................................3

1.1 Khi nim mng IP/WDM ...................................................................................3

1.2 L do chn IP/WDM ............................................................................................7

CHNG II K THUT LU LNG IP/WDM .....................................................10

2.1 M hnh ho lu lng vin thng .....................................................................10

2.1.1 M hnh lu lng d liu v thoi c in ................................................10

2.1.2 Cc m hnh lu lng d liu l thuyt .....................................................112.1.3 Mt m hnh tham chiu bng thng ..........................................................12

2.2 Bo v v ti cu hnh ........................................................................................18

2.3 Cc m hnh bo v v ti cu hnh trong mng IP/WDM .................................19

2.4 Khi nim k thut lu lng IP/WDM .............................................................20

2.5 M hnh ho k thut lu lng IP/WDM ..........................................................21

2.5.1 K thut lu lng chng ln ......................................................................21

2.5.2 K thut lu lng tch hp ........................................................................232.5.3 Nhn xt .....................................................................................................23

2.6 M hnh chc nng ca k thut lu lng IP/WDM .........................................25

2.6.1 C s d liu thng tin trng thi mng IP/WDM ......................................27

2.6.2 Qun l giao din IP vi WDM ...................................................................29

2.6.3 Khi to ti cu hnh ..................................................................................30

2.6.4 o kim v gim st lu lng ..................................................................31

2.6.5 Gim st hiu nng tn hiu quang ............................................................382.7 K thut lu lng MPLS ..................................................................................39

2.7.1 Cn bng ti ................................................................................................39

2.7.2 Gim st mng ............................................................................................43

CHNG III TI CU HNH TRONG K THUT LU LNG IP/WDM ...... .. .46

3.1 Ti cu hnh m hnh o ng i ngn nht .....................................................46

3.1.1 M hnh o c quy tc v bt quy tc .........................................................48

3.1.2 Thit k m hnh ........................................................................................493.1.3 Mt s thut ton da trn kinh nghim .....................................................49

Nguyn Th Cng, D2001VT i


2/112


3.1.4 Dch chuyn m hnh o .............................................................................55

3.2 Ti cu hnh cho cc mng WDM chuyn mch gi ..........................................59

3.2.1 Tng quan v ti cu hnh WDM chuyn mch gi ...................................59

3.2.2 Cc iu kin ti cu hnh ..........................................................................613.2.3 Mt trng hp thc t ...............................................................................62

3.2.4 M t thut ton da trn kinh nghim .......................................................64

3.2.5 Tho lun v thut ton ..............................................................................71

3.2.6 Dch chuyn ti cu hnh ng i ngn nht.............................................71

CHNG IV PHN MM X L LU LNG IP/WDM .....................................74

4.1 Phn mm k thut lu lng IP/WDM .............................................................74

4.2 Kin trc phn mm cho k thut lu lng chng ln ......................................74

4.3 Kin trc phn mm cho k thut lu lng tch hp .........................................77

4.4 K thut lu lng IP - giao thc iu khin mng (IP TECP) ..........................79

4.5 Giao din ngi s dng - mng IP/WDM (UNI) .............................................84

4.6 K thut lu lng WDM - giao thc iu khin mng (WDM TECP) ............ .91

4.7 K thut lu lng phn hi vng kn................................................................ 99

4.7.1 Qu trnh trin khai m hnh mng ...........................................................100

4.7.2 Hi t mng ..............................................................................................101

KT LUN ...............................................................................................................103

TI LIU THAM KHO ..........................................................................................106

Nguyn Th Cng, D2001VT ii


3/112


Nguyn Th Cng, D2001VT iii


4/112

n tt nghip i hc Thut ng vit tt

THUT NG VIT TT

Vit tt Ting Anh Ting VitANSI American National Standard

InstituteVin tiu chun quc gia Hoa K

ARP Address Resolution Protocol Giao thc phn gii a chATM Asynchronous Transfer Mode Ch truyn dn khng ng bBGP Border Gateway Protocol Giao thc cng binCSPF Constraint-based Shortest

Path First Routingnh tuyn ng i ngn nhttrc tin da trn rng buc

DCN Data CommunicationNetwork

Mng truyn thng d liu

DHCP Dynamic Host ConfigurationProtocol

Giao thc cu hnh host ng

DHP Demand Hop-count Productheuristic algorithm

Thut ton da trn kinh nghimtch m hop nhu cu

ECMP Equal Cost Multiple Path a ng ng chi phFBM Fractional Brownian Motion Chuyn ng phn mnh

BrownianFTP File Transfer Protocol Giao thc truyn fileGMPLS Generalized Multiprotocol

Label SwitchingChuyn mch nhn a giao thctng qut

GUI Graphical User Interface Giao din ngi s dng hoHTDA Heuristic Topology Design

AlgorithmThut ton thit k m hnh datrn kinh nghim

HTTP Hypertext Transfer Protocol Giao thc truyn siu vn bnICMP Internet Control Message

ProtocolGiao thc bn tin iu khinInternet

ID Identifier B nhn dngIETF Internet Engineering Task

ForceNhm k s Internet

Ifmanager Interface manager Khi qun l giao dinIP Internet Protocol Giao thc InternetLAN Local Area Network Mng cc b

LEMS Link Elimination viaMatching Scheme Loi b tuyn ni thng qua lc ghpLMP Link Management Protocol Giao thc qun l tuyn niLSA Link State Advertisement Qung b trng thi tuyn niLSP Label Switched Path ng chuyn mch nhnMAC Medium Access Control iu khin truy nhp mi trngMIB Management Information

BaseC s thng tin qun l

MLDA Minimum-delay LogicalTopology Design Algorithm

Thut ton thit k m hnh logicti thiu ho tr

MPLS Multiprotocol LabelSwitching Chuyn mch nhn a giao thc

Nguyn Th Cng, D2001VT iv


5/112


MSN Manhattan Street Network Mng ph ManhattanMTU Maximum Transmission Unit n v truyn dn ti a

NC&M Network Control andManagement

Qun l v iu khin mng

NE Network Element Phn t mngNGI Next Generation Internet Internet th h k tipNMS Network Management System H thng qun l mngNSFNETOADM Optical Add/Drop Multiplexer Khi xen/tch quangOAM Operation and Maintenance Hot ng v bo trOAM&P Operation, Administration,

Maintenance and ProvisioningHot ng, qun tr, bo tr vgim st

OC-12 Optical Carrier Level 12(622,08 Mb/s)

Mc mang quang 12(622,08 Mb/s)

OC-3 Optical Carrier Level 3(155,52Mb/s)

Mc mang quang 3(155,52Mb/s)





OHTMS LP-based One-Hop TrafficMaximisation Scheme

Lc ti u ho lu lng nhop da trn LP

OIF Optical InternetworkingForum

Din ng lin mng Internetquang

OLS Optical Label Switching Chuyn mch nhn quangOMP Optimized Multi Path a ng ti uOSCP Optical Switch Control

ProtocolGiao thc iu khin chuyn mchquang

OSPF Open Shortest Path FirstProtocol

Giao thc ng i ngn nhttrc tin m

OXC Optical Cross Connect u cho quangPC Personal Computer My tnh c nhnQoS Quality of Service Cht lng dch vRAM Random Access Memory B nh truy cp ngu nhinRARP Reverse Address Resolution

ProtocolGiao thc phn gii a ch ngc

RD Residual Demand heuristicalgolrithm

Thut ton da trn kinh nghimnhu cu d tha

RDHP Residual Demand Hop-countProduct heuristic algolrithm

Thut ton da trn kinh nghimtch m hop nhu cu d tha

RSVP Resource ReservationProtocol

Giao thc t trc ti nguyn

SCSI Small Computer SystemsInterface

Giao din cc h thng my tnhnh

SDH Synchronous DigitalHierarchy Phn cp s ng b

Nguyn Th Cng, D2001VT v


6/112


SNMP Simple Network ManagementProtocol

Giao thc qun l mng n gin

SNR Signal-to-Noise Ratio T l tn hiu trn nhiuSONET Synchronous Optical Network Mng quang ng bSPF Shortest Path First ng i ngn nht trc tinSRLG Shared Risk Link Group Nhm tuyn ni nguy him chia sTCP Transmission Control

ProtocolGiao thc iu khin truyn dn

TE Terminal Equipment, TrafficEngineering

Thit b u cui, k thut lulng

TECP Traffic Engineering to ControlProtocol

K thut lu lng cho giao thciu khin

TELNET Remote Telminal protocol Giao thc u cui xaTILDA Traffic Independent Logical

Topology Design AlgorithmThut ton thit k m hnh logicc lp lu lng

TMN TelecommunicationsManagement Network

Mng qun l vin thng

TTL Time To Live Thi gian sngUDP User Datagram Protocol Giao thc Datagram ngi s

dngUNI User to Network Interface Giao din ngi s dng-mngVPC Virtual Path Connection Kt ni ng oVPN Virtual Private Network Mng c nhn oWADM Wavelength Add/Drop

MultiplexerB ghp knh xen/tch bc sng

WAN Wide Area Network Mng din rngWDM Wavelength Amplifier B khuch i bc sngWSXC Wavelength Selective Cross

ConnectKhi u cho la chn bc sng

Nguyn Th Cng, D2001VT vi


7/112

n tt nghip i hc Li ni u

LI NI U

Xu hng giao thc IP tr thnh tng hi t cho cc dch v vin thng ngy

cng tr nn r rng. Pha trn tng IP, vn ang xut hin ngy cng nhiu cc ng

dng v dch v da trn nn IP. Nhng u th ni tri ca lu lng IP ang t ravn l cc hot ng thc tin k thut ca h tng mng nn c ti u ho cho

IP. Mt khc, quang si, nh mt cng ngh phn tn, ang cch mng ho ngnh

cng nghip vin thng v cng nghip mng nh dung lng mng cc ln m n

cho php, qua cho php s pht trin ca mng Internet th h sau. S dng cng

ngh ghp knh theo bc sng WDM da trn nn mng hin ti s c th cho php

nng cao ng k bng thng m vn duy tr c hin trng hot ng ca mng. N

cng c chng minh l mt gii php hiu qu v mt chi ph cho cc mng

ng di.

Khi s pht trin trn ton th gii ca si quang v cc cng ngh WDM, v d

nh cc h thng iu khin v linh kin WDM tr nn chn mui, th cc mng quang

da trn WDM s khng ch c trin khai ti cc ng trc m cn trong cc mng

ni th, mng vng v mng truy nhp. Cc mng quang WDM s khng ch cn l cc

cc ng dn im-im, cung cp cc dch v truyn dn vt l na m s bin i

ln mt mc mm do mi. Tch hp IP v WDM truyn ti lu lng IP qua

cc mng quang WDM sao cho hiu qu ang tr thnh mt nhim v cp thit.Kho lun tt nghip ca em s xem xt v IP trn nn cc mng quang WDM

c bit s tp trung vo k thut lu lng IP/WDM. Kho lun s tp trung trnh by

v cc c ch c bn v kin trc phn cng cng nh phn mm trin khai cc

mng quang WDM cho php truyn dn lu lng IP v s gm c bn chng:

Chng I: Tng quan v IP/WDM. Chng ny s trnh by khi nim

mng IP/WDM, a ra ba xu hng chng giao thc cho mng ny, cc

u nhc im ca tng xu hng. L do v sao IP/WDM li c chn lgii php cho tng lai cng s c ch ra trong chng I

Chng II: K thut lu lng IP/WDM. Chng II s trnh by mt s

vn chung trong k thut lu lng, khi nim k thut lu lng

IP/WDM, hai phng php trin khai, m hnh chc nng ca k thut lu

lng IP/WDM v k thut lu lng MPLS p dng cho IP/WDM.

Chng III: Ti cu hnh trong k thut lu lng IP/WDM. Chng

ny s tp trung i su vo cc vn : ti cu hnh m hnh o ng i

ngn nht, ti cu hnh cho mng WDM chuyn mch gi, m t v tho

Nguyn Th Cng, D2001VT 1


8/112

n tt nghip i hc Li ni u

lun v mt thut ton c th v cui cng l dch chuyn ti cu hnh

ng i ngn nht.

Chng IV: Phn mm x l lu lng IP/WDM. Trong chng IV,

cc kin trc phn mm cho cc xu hng k thut lu lng, chi tit v

giao din gia iu khin mng v k thut lu lng, v gia k thut lu

lng IP v k thut lu lng WDM trong trng hp k thut lu lng

chng ln s c trnh by.

Mc d c nhiu c gng song do thi gian v trnh c hn nn kho lun

ny chc chn khng trnh khi nhng thiu st. Rt mong nhn c nhng kin

ng gp ca cc thy c v cc bn.

Nhn y, em xin gi li cm n chn thnh ti thy gio T.S L Ngc Giao

to mi iu kin v tn tnh hng dn em trong qu trnh thc hin n.

Em cng xin gi li cm n ti cc thy c trong khoa Vin Thng I gip

em trong thi gian qua.

Xin gi li cm n n gia nh, bn b v ngi thn - nhng ngi lun

gip , c v v kp thi ng vin ti trong sut thi gian qua.

H Ni, ngy thng nm 2005Sinh vin

Nguyn Th Cng



9/112

n tt nghip i hc Chng I. Tng quan v IP/WDM

CHNG I TNG QUAN V IP/WDM

1.1 Khi nim mng IP/WDM

Mng IP/WDM c thit k truyn dn lu lng IP trong mt mng quang

cho php WDM tn dng s ph bin ca kt ni IP v dung lng bng thng ccln ca WDM. Hnh 1.1 di y ch ra vic truyn dn cc gi tin IP hoc cc tn

hiu SONET/SDH thng qua mng WDM. Mt khi iu khin bng phn mm s

iu khin ma trn chuyn mch. y, IP, vi vai tr l cng ngh lp mng, s

da trn tng d liu cung cp:

ng khung (v d nh SONET hay Ethernet)

Pht hin li (v d nh kim tra CRC)

Sa li (v d nh yu cu pht li t ng ARQ)Mt vi cc chc nng tng lin kt c th hin trong giao din v d nh cc

giao din khch xen/tch hay cc giao din truyn dn nh vt l.

MUX

MUX

IP IP SONET/SDH IP IP SONET/SDH

Gigabit, EthernetSONET

Cc cng u ra tn hiu(Giao din khch)

Ma trnchuyn mch

Cc cng u vo tn hiu(Giao din khch)

Lu lng vo ra

Si quang

B pht pCc knh bc

sng

KHI IU KHIN

Hnh 1.1 Truyn ti gi tin IP trn cc knh bc sng

Mt mc tiu ca mng quang l cung cp truyn dn trong sut quang t u

cui ti u cui ti thiu ho tr mng. iu ny i hi cc giao din ton quang

v cc ma trn chuyn mch ton quang cho cc thnh phn mng trung gian v bin

gii mng. B pht p c s dng khuych i tn hiu quang. Tn ti cc b

pht p ton quang (cc laser bin i c) v cc b pht p quang-in-quang

(O-E-O). Hnh cng ch ra hai loi lu lng l IP (v d nh Gigabit Ethernet) v

SONET/SDH v do i hi cc giao din gia Gigabit Ethernet v SONET/SDH.



10/112


Trong trng hp cc kt ni a truy nhp, mt tng con ca tng lin kt d liu l

giao thc truy nhp mi trng (MAC) s lm trung gian truy nhp chia s kt ni

sao cho tt c cc node u c c hi truyn d liu.

Hin ang tn ti ba xu hng chnh truyn dn IP trn nn WDM (Hnh 1.2).Xu hng th nht l truyn dn IP trn ATM, sau qua SONET/SDH v cui cng

l si quang WDM. y WDM c dng nh l cng ngh truyn dn song song

vi tng vt l. u im chnh ca phng php ny l nh vic s dng ATM, cc

loi lu lng khc nhau vi cc i hi QoS khc nhau c th c mang trn cng

mt si quang.

Hnh 1.2 Ba xu hng cho IP/WDM (tng d liu)

Mt u im khc khi dng ATM l kh nng s dng k thut lu lng v

mm do trong vic gim st mng ca ATM. N b sung cho nh tuyn lu lng n

lc ti a (best effort) ca IP truyn thng. Tuy nhin, xu hng ny b cho l phc

tp, tng chi ph mng v c xu hng to ra cc nghn c chai tnh ton cc mng

tc cao. N c gii quyt bi s xut hin ca k thut MPLS trong tng IP. Cc

c tnh chnh ca MPLS nh sau:

S dng mt nhn n gin v c di c nh xc nh dng/tuyn.

Tch ring d liu chuyn tip v thng tin iu khin. Thng tin iu

khin c dng thit lp ng i ban u nhng cc gi tin c vn

chuyn ti node k tip da theo nhn trong bng chuyn tip.

Vi mt m hnh chuyn tip ng nht v c n gin ho, cc mou IP ch c x l v kim tra ti cc bin gii ca cc mng MPLS v

Nguyn Th Cng, D2001VT

IP

ATM IP/MPLS

SONET/SDH SONET/SDH IP/MPLS

WDM WDM WDM

4


11/112


sau cc gi tin MPLS c chuyn tip da theo cc nhn (thay v

phi phn tch cc mo u gi tin IP c ng gi).

MPLS cung cp a dch v. V d mt mng ring o VPN thit lp bi

MPLS c mt mc u tin c th c xc nh bi trng tng

ng chuyn tip FEC (Forwarding Equivalence Class).

Cho php phn loi cc gi tin da theo chnh sch. Cc gi tin c kt

hp trong FEC nh vic s dng mt nhn. Vic sp xp gi tin vo FEC

c thc hin ti bin gii mng da theo trng dch v hoc a ch

ch trong phn mo u ca gi tin.

Cung cp cc c ch cho php k thut lu lng. Cc c ch ny c

trin khai cn bng ti tuyn nh gim st lu lng v thc hin chnh

cc dng mt cch tch cc hoc d on trc. Trong mng IP hin ti, kthut lu lng l rt kh nu khng ni l khng th v chuyn i hng

lu lng dng cc chnh sa nh tuyn khng trc tip l khng hiu

qu v n c th gy ra tc nghn nghim trng hn u trong mng.

MPLS cho php nh tuyn hin bi n cung cp v tp trung ch yu vo

chuyn tip da trn trng. Ngoi ra MPLS cng cung cp cc cng c

cho iu khin lu lng nh k thut ng ngm, k thut trnh v

phng vng lp, k thut ghp dng.

Xu hng th hai l IP/MPLS trn nn SONET/SDH v WDM. SONET/SDH

cung cp mt s c tnh hp dn sau cho xu hng ny:

SONET cung cp mt phn cp ghp knh tn hiu quang tiu chun qua

cc tn hiu tc thp c ghp thnh cc tn hiu tc cao.

SONET cung cp mt tiu chun khung truyn dn.

Mng SONET c kh nng bo v/hi phc hon ton trong sut i vi

cc tng cao hn, y l tng IP.

Cc mng SONET thng s dng m hnh ring. S bo v SONET c th l:

1+1, ngha l d liu c truyn dn trn hai hng ngc nhau v

ch th tn hiu c cht lng tt hn s c la chn.

1:1, ch ra rng c mt ng bo v dnh ring cho ng chnh

n:1, th hin mt s ng chnh (n) chia s chung mt ng bo v.

Thit k ca SONET cng tng cng OAM&P truyn cc thng tin cnh

bo, iu khin v hiu nng gia cc h thng v gia cc mc mng. Tuy nhin,

SONET mang qu nhiu thng tin mo u v chng li c m ho nhiu mc



12/112


khc nhau. Mo u ng (POH) c mang t u cui ti u cui. Mo u tuyn

(LOH) c s dng cho tn hiu gia thit b kt cui tuyn v d nh cc b ghp

knh OC-n. Mo u on (SOH) c s dng thng tin gia cc thnh phn

mng lin k v d nh cc b ti to. Vi mt OC-1 vi tc l 51,84 Mbps, phn

ti ca n ch c kh nng truyn dn mt DS-3 vi tc bit l 44,736 Mbps.

Xu hng th ba ng dng IP/MPLS trc tip trn WDM v l gii php hiu

qu nht. Tuy nhin, n li yu cu tng IP c trch nhim bo v v phc hi tuyn.

N cng yu cu mt khun dng khung c n gin ho iu khin li truyn

dn. C mt vi la chn khun dng khung cho IP trn nn WDM. Mt vi cng ty

pht trin mt chun mi l Slim SONET/SDH. N cung cp cc chc nng tng

t nh SONET/SDH nhng vi cc k thut hin i thay th mo u v ghp kch

thc khung vo kch thc gi tin.

Mt v d khc l ng dng khun dng khung Gigabit Ethernet. Chun 10-

Gigabit Ethernet mi c thit k l dnh ring cho cc h thng WDM ghp cht.

S dng khun dng Ethernet, cc my ch bt k hng no ca kt ni cng khng

cn sp xp ln mt khun dng giao thc khc (v d nh ATM) truyn dn.

Cc mng IP truyn thng s dng bo hiu trong bng nn lu lng bo hiu

v iu khin c truyn dn trn cng mt ng v tuyn. Mt mng quang WDM

c mt mng truyn thng ring r dnh cho cc bn tin iu khin. Nh vy n sdng bo hiu ngoi bng nh trong hnh 1.3

Lu lng d liu

Bo hiu ngoi bng

Bo hiu trong bng

Lu lng d liuv iu khin

(a) Mng WDM

(b) Mng IP truyn thng

Hnh 1.3 Lu lng d liu v iu khin trong mng IP v WDM



13/112


Trong mt phng iu khin, IP trn nn WDM c th h tr nhiu kin trc

mng khc nhau v s la chn kin trc ch ph thuc vo mi trng mng hin c,

nh qun tr v ch s hu mng.

1.2 L do chn IP/WDMIP l giao thc c thit k xc nh a ch mng lp ba v t nh tuyn

qua cc mng con vi cc cng ngh lp hai khc nhau. Pha trn tng IP tn ti rt

nhiu cc dch v v ng dng da trn nn tng IP khc nhau. Trong khi pha di

lp IP th si quang s dng cng ngh WDM l cng ngh truyn dn ha hn nht,

cho php dung lng mng v cng ln p ng c s pht trin ca Internet.

Cng ngh ny s tr nn hp dn hn nhiu khi gi thnh ca cc h thng WDM

gim i.

Mt phng iu khin c nhim v truyn dn cc bn tin iu khin chuyn

i cc thng tin sn c v c th tip cn c, tnh ton cng nh thit lp ng

truyn dn d liu. Mt phng d liu c nhim v truyn dn lu lng ng dng v

lu lng ngi s dng. Mt chc nng in hnh ca mt phng d liu l m v

chuyn tip gi tin. IP khng phn tch mt phng d liu v mt phng iu khin v

do n i hi cc c ch QoS ti cc b nh tuyn phn bit cc bn tin iu

khin v cc gi tin d liu.

Mt h thng iu khin mng WDM truyn thng s dng mt knh iu khinring bit, cn c gi l mng truyn thng d liu, truyn dn cc bn tin iu

khin. Mt h thng qun l v iu khin mng WDM, theo TMN, c trin khai

theo cu trc tp trung. cho php m rng a ch, cc h thng ny dng mt phn

cp qun l. Kt hp IP v WDM c ngha l, trong mt phng d liu ta c th yu

cu cc ti nguyn mng WDM chuyn tip lu lng IP mt cch hiu qu cn trong

mt phng iu khin ta c th xy dng mt mt phng iu khin ng b. IP/WDM

cng nh a ch tt c cc mc trung gian ca cc mng quang intra- v inter-WDM

v cc mng IP.

Cc ng c thc y IP/WDM bao gm:

Cc mng quang WDM c th nh a ch lu lng Internet ang pht

trin bng cch khai thc c s h tng si quang sn c. S dng cng

ngh WDM c th tng mt cch ng k vic tn dng bng thng si

quang.



14/112


Hu ht lu lng d liu qua cc mng l IP. Gn nh tt c cc ng

dng d liu u cui ngi s dng u s dng IP. Lu lng thoi

truyn thng cng c th ng gi nh cc k thut VoIP.

IP/WDM tha hng s mm do v kh nng thch ng m cc giao thc

iu khin IP cho php.

IP/WDM c th t c hoc nhm vo s phn b bng thng ng

theo nhu cu (hay gim st thi gian thc) trong cc mng quang. Bng

cch pht trin t cc mng quang iu khin tp trung truyn thng sang

mng t iu khin phn b, mng IP/WDM tch hp khng nhng gim

thiu chi ph qun l mng m cn cung cp phn b ti nguyn ng v

gim st dch v theo nhu cu.

Vi s gip ca cc giao thc IP, IP/WDM c th hy vng nh a chc WDM hay cc nh khai thc hot ng trung gian NE.

Cc mng quang WDM i hi mt phng iu khin thng nht v

c kh nng phn cp gia cc mng con c cung cp bi cc nh

khai thc WDM khc nhau. Cc giao thc iu khin IP c trin

khai rt rng ri v c chng minh l c kh nng phn cp. S

xut hin ca MPLS khng ch b sung cho IP truyn thng k thut

lu lng v kh nng QoS bin i m cn a ra mt mt phng

iu khin trung tm IP thng nht gia cc mng.

S khc bit gia cc thit b mng WDM i hi s lin kt gia cc

nh khai thc trung gian. V d nh cc WADM khng trong sut i

hi cc khun dng tn hiu nht nh v d nh tn hiu SONET/SDH

cc giao din khch xen/tch ca chng. S lin kt hot ng gia

WDM i hi s xut hin ca tng mng m y l IP.

IP/WDM c th t c s phc hi ng bng cch phn mc cc c

ch iu khin phn tn c dng trong mng. T quan im dch v, cc mng IP/WDM c th li dng cc c ch,

chnh sch, m hnh, c cu QoS c ngh v pht trin trong mng

IP.

Rt kinh nghim t tch hp IP v ATM, IP v WDM cn mt s tch hp

mnh hn na tng tnh hiu qu v kh nng mm do. V d nh, IP

trn nn ATM c in l tnh v phc tp v chuyn i a ch IP sang

ATM l bt buc phi chuyn i gia cc a ch IP v cc a ch ATM.



15/112


Tch hp IP/WDM s cho php truyn dn mng quang mt cch hiu qu, lm

gim chi ph cho lu lng IP v tng cng s tn dng mng quang.



16/112


17/112

n tt nghip i hc Chng II. K thut lu lng IP/WDM

knh b chim trong mt khong thi gian bt k. R rng l nghn cuc gi, B c, th

hin QoS tt hn t quan im ca khch hng. Gi s c mt h thng tn tht

M/G/n/n, trong n l s knh trn mt tuyn ni, cuc gi n tun theo qu trnh

Poisson vi tc v cc thi gian chim cuc gi l phn b c lp v bng nhau

theo phn b h th mi quan h gia nghn cuc gi, mc tp trung lu lng v

thi gian chim trung bnh c cho bi biu thc nghn Erlang nh sau:

Bc = Erlang (n,) ==

n

i

i

n

i

n

0 !

!

b) M hnh lu lng d liu

Lu lng d liu c th c m t nh s dng cc m hnh hng i. Lulng d liu c biu din bi tc n ca gi tin , chiu di gi tin trung bnh

L, v thi gian truyn dn gi tin 1/. Gi s rng R h thng biu din tc tuyn

ni hay ni cch khc l s n v d liu trong mt n v thi gian th thi gian

truyn dn gi tin s l L/R. Khi tng s lu lng s c th hin bi ti lu

lng :

R

L.

==

T quan im ca ngi s dng th c tnh quan trng l QoS. QoS c biu

din bi Pz, l xc sut mt gi tin phi i lu hn mt gi tr tham chiu z. Gi thit

mt h thng hng i M/M/1, c cc gi tin n tun theo qu trnh Poisson vi tc

v chiu di gi tin phn b c lp v bng nhau theo phn b lu tha L th mi

quan h gia kh nng ti lu lng h thng, QoS c cho bi cng thc sau:


18/112


quan thng k. iu ny c ngha l lu lng s trng ging nhau trong tt c cc di

thi gian v c th s dng mt tham s duy nht l tham s Hurst miu t c tnh

phn mnh. Cc c tnh lu lng Ethernet ny khng th din t nu s dng cc m

hnh lu lng c in nh l m hnh Poisson.

Lu lng WAN Internet cng c nghin cu c hai mc o l mc gi

tin v mc kt ni. Nghin cu ch ra rng ti mc gi tin, phn b thi gian n

gia cc gi tin TELNET l khng tng nhanh theo hm lu tha nh cc m hnh c

in. Cn ti mc kt ni i vi cc phin TELNET tch cc th tc n kt ni

tun theo qu trnh Poisson (vi tc c nh theo tng ting ng h). Tuy nhin,

nghin cu cng ch ra rng ti mc kt ni, i vi cc kt ni trong phin khi to

ngi s dng (FTP, HTTP) v my khi to th tc n kt ni c tnh bng n,

i khi l tng quan v khng tun theo qu trnh Poisson.

th hin c tnh bng n ca lu lng d liu Internet th c th cn phi

s dng cc phn b s m con nh l cc phn b Log-normal, Weibull, Pareto. i

vi cc qu trnh c ph thuc di di th cc qu trnh t tng quan nh l chuyn

ng Brownian phn mnh c th c s dng.

2.1.3 Mt m hnh tham chiu bng thng

K thut lu lng vng kn c th c thc hin da trn phn hi v tham

chiu bng thng. K thut lu lng vng kn da trn phn hi s c trnh bytrong phn 4.2. Tham chiu bng thng l mt cng c hu ch cho k thut lu lng.

Cc d on bng thng trong tng lai c th c s dng khi to ti cu hnh

mc mng. Nh vic d on bng thng ca dng lu lng, c th xc nh c

cc i hi v dung lng ca tuyn ni IP/WDM v do vy s quyt nh c thc

hin ti cu hnh hay khng.

Dng lu lng IP l mt dng cc gi tin IP n hng (ca cng mt lp lu

lng) gia hai u cui. Cc u cui c th l cc b nh tuyn lin k trong trnghp cc dng lu lng IP l lu lng chy trn tuyn ni nm gia hai b nh

tuyn. Tng ng nh th, cc u cui cng c th khng phi l cc b nh tuyn

lin k. Mt dng lu lng IP l n hng v iu ny s dn ti tnh khng i

xng ca lu lng gia cc u cui. Cho trc mt dng lu lng th iu ta mong

mun l xc nh cc tnh cht v c lng c bng thng ca n. Mc d phng

php di y c th p dng cho nhiu kiu lu lng nhng n c hi vng l s

c kh nng c lng c ti mong mun ca kt ni IP v sau cc c lng

ny s c s dng thc hin cc quyt nh ti cu hnh.



19/112


Khong thi gian d on xc nh ln thi gian d on trong tng lai.

Khong thi gian cho ti cu hnh mc mng c xc nh bi nhiu yu t. Ngi ta

mong mun ti cu hnh mc mng c kh nng phn ng trc cc thay i trong xu

hng lu lng (chng hn nh cc thay i ti trong mt ngy). Mt khc khong

thi gian ti cu hnh t nht cng phi bng thi gian ca mt th tc ti cu hnh.

Khong thi gian ti cu hnh bao gm cc thnh phn sau:

Thi gian thc hin mt d on

Thi gian tnh ton mt m hnh mi

Thi gian dch chuyn t m hnh hin ti ti m hnh mi

Thi gian thc hin d on bng thng ph thuc vo phc tp tnh ton

ca m hnh d on. Thi gian tnh ton m hnh mi ph thuc vo phc tp

ca cc thut ton hay gii php da trn kinh nghim thc hin vic thit k m

hnh . Cn thi gian dch chuyn t cu hnh hin ti sang cu hnh mi li ph

thuc vo chu trnh dch chuyn c s dng. Gi thit rng chu trnh dch chuyn

bao gm mt chui cc thit lp v loi b tng tuyn ni IP/WDM ring r. Khi

thi gian dch chuyn s bng tng thi gian thit lp v loi b cc tuyn ni

IP/WDM vi thi gian cc giao thc nh tuyn n nh sau mi thay i m hnh.

Da trn cc nhn xt trn, ngi ta tha nhn mt khong thi gian ti cu hnh

nht nh. y l khong thi gian xc nh tnh thng xuyn thc hin ti cu hnhmc mng. Thi gian ny c gi l khong thi gian th (khc vi khong thi gian

mn - thi gian cho cc php o lu lng). Khong thi gian th l mt thng s c

th thay i c tu theo thit k. nh hng ca cc gi tr khc nhau ca thng s

thi gian th c nh gi.

D on bng thng cho dng lu lng trong khong thi gian k tip ph

thuc vo mt s yu t sau:

Gi trong ngy v ngy trong tun: tn ti mi tng quan gia ngytrong tun v gi trong ngy vi ln lu lng Internet.

Cc mi tng quan t cc mu thi gian trc : ln lu lng trong

qu kh gn s nh hng ti ln lu lng trong tng lai.

Qu trnh n ca lu lng: khng th ch d on cc qu trnh ny l

cc qu trnh Poisson. Cn phi tnh n cc c tnh t tng quan ca

dng lu lng trong .

Mc ch l tm kim mt m hnh thng s da trn kinh nghim c th d

on c bng thng lu lng trong khong thi gian k tip. M hnh s tn dng



20/112


cc thng tin o c lu lng v gi thit rng qu trnh n ca lu lng l qu

trnh t tng quan. M hnh di y c xut bi A. Neidhardt v J. Hodge

ti Bellcore v c dng d on dung lng ca mt ATM VPC mang lu lng

IP v c m rng trong d n NGI Supernet NC&M ti Bellcore/Telcordia.

Qu trnh chuyn ng phn mnh Brownian

Qu trnh chuyn ng phn mnh Brownian (FBM) l mt qu trnh t tng

quan c m t bi ba thng s l: tc n trung bnh m, tham s dao ng a v

thng s Hurst, H. Mt mng IP/WDM c th m hnh ho tc n nh FBM

xem xt n s dao ng ca tng lu lng mn ho trong khong thi gian th. FBM

c nh ngha nh sau:

A(t) = mt +am

Z(t) trong

Gi thit rng ngi ta cn xc xut trn dng trn b chn ngha l:

P(Q > B) exp (-2

2z)

th biu thc cho tc dch v ca hng i C s c dng nh sau:



21/112


+

HHHHH HHBazmmC 11

1

1

2

1

2

1

2

1

)1(

Cc nguyn l tham chiu lu lng

Nguyn l u tin l bng thng lu lng trong khong thi gian k tip phthuc nhiu vo lu lng thy trong dng lu lng ca cng khong thi gian

ca tun trc .

Nguyn l ny phn nh m hnh ln lu lng ph thuc ln vo gi trong

ngy v ngy trong tun c quan st thy trong cc tuyn ni. Do vy, ln lu

lng trung bnh trong khong thi gian k tip s gn nh ging ht nh ln

xut hin trong cng thi im ca ngy, ca cng th hm ca tun trc . V

iu ny c th c biu din bi biu thc:

[ ]dhFF ,0

Trong F[h,d] l lu lng quan st thy ti gi h ca ngy d trong tun trc

. Gi s rng tc pht trin ca lu lng t tun ny sang tun khc c m

hnh bi mt hm c thng s . Cng gi thit rng hm tng trng ny l hm m:

0F

01

eFF =

Trong l thng s m hnh c c lng t cc php o lu lng. Gi

thit rng W0 v W1 l tng lu lng o c trong hai tun lin trc trong dng lu

lng th c th xc nh t phng trnh sau:

0

01W

weW

=

Nguyn l th hai l d on bng thng lu lng trong khong thi gian k

tip s khc vi lu lng c quan st thc t trong cng mt cch m php d

on trong khong thi gian lin trc thc hin.

Cho A(h-1) l ln lu lng thc t o c trong khong thi gian (h-1). Githit F(h-1) l ln lu lng d on cho khong thi gian (h-1) th:

+

)1()1(

)1(

hF

hAl t l xem xt s khc nhau gia gi tr d on v gi

tr thc t trong khong thi gian lin trc. Do :

+

= )1()1(

)1(12 hF

hAFF

trong c th c chn bng cch lm ph hp vi d liu o c trc. V d nh ngi ta c th chn gi tr sao cho sai s do t l c cho bi:



22/112


)1(

)1(

)(

)(

hF

hA

hF

hA

l nh nht cho d liu trong qu kh. Ni cch khc, c th chn sao cho ti

thiu ho gi tr:2

)1(

)1(

)(

)(

hF

hA

hF

hAE

trong E l ton t d on. N s cho kt qu l:

2

)1(

)1(

)1(

)1(

)(

)(

=

hF

hAE

hF

hA

hF

hAE

Gi thit rng mt qu trnh n FBM vi tc trung bnh F2, kch thc b

nh tuyn l B v xc xut tn tht gi tin s b chn trn bi th iu kin cho

dung lng s c biu din bi:

),,,(F 21

223zBHaFF H+=

trong

=

HHHH HHBazzBHa 11

1

1

2

1

2

1

)1(),,,(

Di y, n s trnh by hai phng php dng c lng cc thng s a

v H t lu lng o c. Phng php u tin gi nh rng c cc kt qu o

ln lu lng cho mi mt trong N khong thi gian mn lin tip t. Biu th ln

lu lng cho mi khong i l T(i). Khi gi tr c lng ln lu lng trung

bnh s l:

N

iT

m

N

i

== 1

)(

v gi tr c lng ca phng sai s l:

1

))((1

2

=

N

miT

V

N

i

t

Cc gi tr o c th c tng hp thnh k khi khng chng ln vi kch thc

mi khi l kt v c phng sai l Vkt. Khi cho trc hai gi tr c lng phng sai

Vt v Vkt th cc gi tr a v H l hon ton c th xc nh c.



23/112


Trong phng php th hai, thng s H c th c lng t cc im sai khc

thi gian nh sau. Cho mt vt thi gian Xk, k = 1, 2,., chng ta s c mt vt thi

gian tng hp Xk(m), k = 1, 2, bng cch ly trung bnh t cc chui Xk ban u nh

cc khi khng chng ln c ln m. Ngha l:

( )kmmkmm

k XXm

X ++= + ...1

1

)(

Sau i vi cc qu trnh ph thuc di di th ta s c:

[ ] )1(2)( Hm mXV

Do , nu chng ta v [ ](m)XlogV theo log(m) th dc ca th s chnh l

)1(2 H , trong H l gi tr c lng cho H.

Cc thng s m hnh

Cc thng s sau c nh ngha cho m hnh d on bng thng:

Kch thc ca thi gian th: Lc gim st lu lng cho kt qu l

d liu di dng ma trn lu lng. N cha ln lu lng trung bnh

trong mt khong thi gian tinh. ln ca thi gian th chnh l thi

gian s dng tnh trung bnh lu lng trong mt khong thi gian th

bng cch kt hp cc d liu lu lng trong khong thi gian tinh li

vi nhau.

Kch thc b m b nh tuyn: kch thc b m b nh tuyn c

dng trong m hnh d on ln ca mt dng lu lng.

Gii hn xc sut mt gi: thng s ny c dng d on bng thng

ca mt dng lu lng.

Thut ton nh tuyn, m hnh mng: m hnh mng v thut ton nh

tuyn gip xc nh dng lu lng no c yu cu i vi mt kt ni

da trn kt qu ca cc php o dng lu lng t cc b nh tuynbin.

Thng s lu lng o c chnh l ma trn lu lng tinh t b nh tuyn

bin ny ti b nh tuyn bin khc. T thng s o c ny c th rt ra c tt c

cc thng s khc. Cc thng s sau c tnh ton cho mc ch ti cu hnh ti thi

im bt u ca mt khong thi gian th:

Trung bnh th cho cc dng lu lng ca mi cp b nh tuyn bin

vo ra: c tnh ton da trn d liu lu lng tinh o c.



24/112


phc tp ca tnh ton trung bnh th l O(N2) trong N l s lng

b nh tuyn bin trong mng.

Cc trung bnh th v trung bnh tinh ca ln lu lng yu cu cho

mi kt ni n hng: ln lu lng yu cu cho mi tuyn ni c th

tnh c cho c khong thi gian th v tinh da trn ma trn lu lng

t b nh tuyn bin ny ti b nh tuyn bin khc, m hnh mng v

thut ton nh tuyn.

phc tp tnh ton l O(E2) trong E l s lng kt ni trong mng.

Cc thng s d on lu lng F1, F2, F3: i vi mi dng lu lng,

cc thng s d on bng thng F1, F2, F3 c th tnh ton t cc phng

trnh trn. Vic tnh ton ny c thc hin u mi khong thi gian

th.

phc tp ca php tnh l O(N2) trong N l s lng b nh tuyn bin

trong mng.

V s ti cu hnh lm thay i cu hnh ca mng IP nn mt vi thng s s cn

phi c tnh ton li sau khi cu hnh. c bit l trung bnh th v tinh cho cc

dng lu lng i vi mi tuyn ni s cn tnh ton li sau khi xy ra ti cu hnh.

Cc thng s iu chnh a, H, v c s dng trong m hnh d on lu lng

v c iu chnh ph hp da trn d liu lu lng o c v d liu lu lngtnh ton. S ph hp cho mi mt trong s cc thng s trn cn phi c tnh ton

li mi khi c ti cu hnh hoc theo chu k (chng hn nh mt ln mt tun).

2.2 Bo v v ti cu hnh

m bo tnh mm do ca dch v mng trc cc li th hai xu hng c

xem xt tm ra mt tuyn mi cho ng i l: mt ng i bo v thit lp trc

v mt ng i ti cu hnh tnh ton ng. Cc k thut bo v ph thuc vo dung

lng d tha trong mng. V mt tuyn bo v cho mi tuyn ang lm vic cthit lp trc nn ti nh tuyn s dng k thut ny th nhanh hn (nh hn 50 ms

trong mng SONET/SDH) v n gin hn ti cu hnh.

Cc k thut bo v cng c phn loi thnh bo v tuyn v bo v ng. S

khc nhau ca chng c ch ra trong hnh 2.1. Trong hnh 2.1(a) th dng lu lng

t A ti E s dng mt ng i A-B-E. Nu nh c li trn kt ni t A ti B th mt

bo v tuyn s trnh tuyn A-B bng cch s dng mt ng c thit k trc l

A-D-C-B v phn cn li ca ng vn c s dng bnh thng nh c ch ra

trong hnh 2.1(b).



25/112


A B

CD

E

A B

CD

E

A B

CD

E

(a) Ch bnh thng (b) Bo v tuyn (c) Bo v ng

Hnh 2.1 Bo v ng v bo v tuyn

Ngc li, mt bo v ng s hon ton khng s dng ng c li na.

N s dng mt ng khc hon ton khng lin quan ti ng ban u. Trong v

d hnh 2.1(c), n s dng ng A-D-C-E thay v ng A-B-E.

Trong khi ti cu hnh c th c s dng hoc l cung cp cc tuyn ni

hiu qu hn sau khi bo v hon thnh hoc l tng cng tnh mm do chng li

cc li nng hn trc khi li u tin c sa. Thng thng th c ch ti cu hnh

l kh chm.

2.3 Cc m hnh bo v v ti cu hnh trong mng IP/WDM

Tu thuc vo mc tiu ca cc chc nng iu khin v bo hiu trong tng

WDM m bo v v ti cu hnh trong mng IP/WDM c th c phn loi thnh ba

m hnh.

M hnh u tin s dng mt khi qun l kt ni quang thng minh v t qun

tr. Chnh xc hn th mt tng quang c hu ht cc chc nng bo hiu v iu

khin, v d nh qun l dung lng v cu hnh, nh tuyn, pht hin m hnh, ti cu

hnh v iu khin ngoi l nh s dng cc chc nng bo hiu v iu khin hon

ton l ca n. Bt li ln nht ca m hnh ny l s d tha cc chc nng bo hiu

v iu khin v cc chc nng qun l mng nh vy c trong tng IP.

Trong m hnh th hai, mi b nh tuyn IP c kt ni nh s dng si quang

v WDM. Do khng c khi nim ng i ngn nht trong m hnh ny. Tt c

cc bo hiu v iu khin u ph thuc vo tng IP.

M hnh th ba c th gi l nh tuyn thng minh quang n gin v l

phin bn trung gian gia hai m hnh trn. Hin nay IETF v OIF ang nghin cu

m hnh ny s dng chuyn mch nhn a giao thc tng qut (GMPLS). Vi m

hnh th ba th vn cy m hnh IP trn nn m hnh WDM s ng vai tr quan

trng trong bo v IP/WDM c bit l khi tng WDM khng h tr bo v ng v

bo v tuyn hoc l tuyn bo v khng lm vic bnh thng do s xut hin nhiu

li cng lc.



26/112


2.4 Khi nim k thut lu lng IP/WDM

K thut lu lng IP/WDM l k thut tn dng cc ti nguyn IP/WDM (v

d nh cc b nh tuyn IP, cc b m, cc chuyn mch WDM, cc si quang v

cc bc sng) mt cch hiu qu, truyn dn cc gi tin v dng lu lng IP. Kthut lu lng IP/WDM bao gm k thut lu lng IP/MPLS v k thut lu lng

WDM nh c ch ra trn hnh 2.2

nh x = T.E

n nh dng

Thit lp ng

M hnh IP

Thit lp m hnh

Ti cu hnh

Ti nguynIP/WDM

Lu lng IP

M hnh IP

WDM T.E.

MPLS T.E.

Hnh 2.2 K thut lu lng IP/WDM (TE)K thut lu lng MPLS gii quyt cc vn v phn b dng v thit k nhn

ng. S dng k thut iu khin ng hin MPLS, k thut lu lng MPLS cho

php cn bng ti trn m hnh IP hin c. Cc MPLS LSP lm vic nh l cc tuyn

o cng chia s mt m hnh IP c nh.

Trong khi k thut lu lng WDM li a ra cc gi nh v mt m hnh IP

tnh trn nn mng WDM. K thut lu lng WDM gii quyt cc vn v thit k

m hnh ng i ngn nht v dch chuyn m hnh IP. Trong cc mng WDM ckh nng ti cu hnh, k thut lu lng MPLS v k thut lu lng WDM lm vic

cc tng khc nhau, ngha l mt tng IP v mt tng WDM. Trong cc mng

chuyn mch gi quang, cc k thut lu lng MPLS v WDM c th c dng theo

m hnh chng ln hoc theo m hnh tch hp. Xu hng u tng t nh IP chng

ln trn nn cc mng WDM c kh nng ti cu hnh (mt phng d liu), trong khi

cc MPLS LSP (cc ng i o) c n nh cho cc mch quang WDM c nh.

Xu hng th hai xy dng cc ng i ngn nht, n nh cc dng trn cc ng

i ngn nht v chuyn tip lu lng theo mt m hnh tch hp. Trong n nycc k thut lu lng MPLS v WDM s c trnh by.



27/112


2.5 M hnh ho k thut lu lng IP/WDM

Nh trnh by trn k thut lu lng trong cc mng IP/WDM c th thc

hin theo hai phng php: k thut chng ln v k thut tch hp.

Vi k thut lu lng IP/WDM chng ln, mi tng IP v WDM c mt khi kthut lu lng ring. S hot ng ca mi mng c th c lp vi mng cn li.

Cc gii php k thut lu lng c pht trin cho cc mng IP hoc cc mng

WDM c th c ng dng trc tip cho mi tng mt cch tng ng. V mt tnh

cht th mng khch-ch chng ln l mt v d cho k thut lu lng chng ln.

Vi k thut lu lng tch hp, s ti u ho hiu nng mng i vi mt mc

tiu nht nh t c nh s kt hp gia c hai thnh phn mng IP v WDM. Vi

s xut hin ca cc phn cng ngy cng tinh vi cho php tch hp chc nng ca c

IP v WDM ti mi thnh phn mng (NE) nn k thut lu lng tch hp c th hot

ng hiu qu hn.

2.5.1 K thut lu lng chng ln

Nguyn l ca k thut lu lng chng ln l s ti u ho t c tng tng

mt. iu ny c ngha l s ti u ho trong mt khng gian nhiu chiu l kt qu

ca mt qu trnh tm kim ln lt theo cc chiu khc nhau. R rng l kt qu ti

u ho ph thuc vo th t tm kim v khng m bo l kt qu ti u ho ton

cc. Chiu no cng xut hin sm trong chui tm kim th cng t c s ti u

ho tt hn. Mt li th ca k thut lu lng chng ln l cc c ch c th c

iu chnh p ng tt nht nhu cu ca mt tng c th (IP hoc WDM) tu theo

cc mc tiu c la chn. Hnh 2.3 m t k thut lu lng chng ln.



28/112


IP T.E. (MPLS T.E)

WDM T.E

WADM

WADM

WADMWADMOXC

WADM

WADMOXC

M hnh WDM

M hnh IP

Hnh 2.3 K thut lu lng chng ln

K thut lu lng chng ln c th xy dng bng vic kt ni cc b nh tuyn

IP vi mng WDM da trn OXC thng qua mt OADM. Cc mng IP/WDM cxy dng theo phng php ny th hin mt mng WDM da trn OXC, tng ch

c h tr bi mng vt l trong tng mng vt l ny c to nn bi cc NE

quang v cc si quang. Mi si quang mang nhiu bc sng m vic nh tuyn

chng l c kh nng ti cu hnh mt cch mm do. Tng khch (ngha l mng o)

hnh thnh bi cc b nh tuyn IP c kt ni bi cc ng i ngn nht da trn

mng vt l . M hnh ca mt mng o c kh nng ti cu hnh c l nh kh

nng ti cu hnh cc ng i ngn nht trong tng my khch. Cc giao din ca mt

b nh tuyn IP kt ni vi OADM l cc giao din c kh nng ti cu hnh c.

iu ny c ngha l cc IP ln cn kt ni vi mt giao din c kh nng ti cu hnh

nh vy c th c thay i bng cch cp nht cu hnh ng i ngn nht c s.

Trong cc mng IP/WDM, iu khin tc nghn khng ch c thc hin tng dng

s dng cng mt m hnh m cn c th c thc hin tng m hnh nh s dng

ti cu hnh ng i ngn nht. Do , khng ch mt ngun lu lng iu chnh

dng cc gi tin ca n trc khi gi n vo mng m chnh bn thn mng cng c

kh nng thch ng trc mt kiu lu lng sau mt thi gian tu chn. Trong tngIP, iu khin tc nghn cung cp nn tng cho k thut lu lng, ngha l lm cch



29/112


no truyn dn cc dng bit theo ng i ca chng mt cch nhanh nht ti ch.

Trong tng WDM, iu khin n nh c s dng qun l cc ti nguyn mng (v

d nh l bc sng) v n nh chng cho cc kt ni IP o. iu khin n nh tng

WDM c th l tnh, ngha l c nh ti thi im bt u ca yu cu kt ni, hoc

c th l ng v c thay i trong thi gian kt ni. Chnh s mm do ny cho

php tng WDM cung cp cc kt ni cho tng pha trn vi cht lng dch v khc

nhau.

2.5.2 K thut lu lng tch hp

Nguyn l ca k thut lu lng tch hp l s ti u ho c thc hin ti c

hai mng WDM v IP ng thi. iu ny c ngha l tm kim c kt qu ti u

ho ton cc trong mt khng gian nhiu chiu. K thut lu lng tch hp c th ng

dng cho cc mng trong chc nng ca c IP v WDM c tch hp ti mi NE.Khi chc nng IP v WDM c tch hp, mt mt phng iu khin tch hp cho c

hai mng l kh thi. iu ny li cung cp s ph hp t nhin cho mt m hnh k

thut lu lng tch hp. Qun l lu lng IP v qun l v iu khin ti nguyn

WDM c xem xt cng nhau. Hnh 2.4 ch ra k thut lu lng tch hp

T.E IP/WDM tch hp T.E IP/WDM tch hp

WDM

WDM WDM(OXC)

WDM(OXC)WDM

WDM

M hnh IP/WDM tch hp

Si a bc sng

Hnh 2.4 K thut lu lng tch hp

2.5.3 Nhn xt

S khc bit gia hai xu hng chng ln v tch hp th hin mi quan h

gia ti u ho hiu nng v n nh ti nguyn. Vi k thut lu lng chng ln, tiu ho hiu nng, v d nh cn bng ti v nh tuyn lu lng, c th c thc



30/112


hin tng IP v hon ton tch bit khi n nh ti nguyn vt l WDM, c thc

hin tng WDM. Do vy, ti u ho hiu nng tng IP c th s dng ti cu hnh

v cc c ch truyn thng khng h lin quan ti ti cu hnh. Khi khng s dng ti

cu hnh th iu c ngha l ti u ho hiu nng t c vi mt tp cc ti

nguyn c nh (cho mt m hnh IP c nh). Khi s dng ti cu hnh, ngha l s

dng n nh ti nguyn ng cho mt m hnh o. Sau ti u ho hiu nng ti

tng IP s la chn da trn lng ti nguyn m n mun xem xt trng thi ti

nguyn ca tng WDM. Chnh tng WDM l ni xy ra n nh ti nguyn vt l trong

thc t. Mt khc, ti u ho hiu nng v n nh ti nguyn mng c kt hp

trong m hnh k thut lu lng tch hp. Nu nh ti u ho hiu nng c lin quan

ti mt tp cc ti nguyn mng bin i th n nh ti nguyn s t ng iu chnh

trong qu trnh ti u ho.Cc m hnh k thut lu lng c th c trin khai di dng tp trung hay

phn tn. Bng 2.1 th hin bn la chn cho trin khai cc m hnh k thut lu

lng. Theo trc gic th xu hng chng ln s thch hp vi dng tp trung hoc

phn cp, trong c mt TE tng IP v mt TE tng WDM v hai TE ny s giao

tip thng qua UNI bin gii WDM hoc cc giao din gia IP NMS v WDM

NMS. Trong m hnh chng ln tp trung, khi qun l NC&M tng IP trung tm v

khi qun l NC&M tng WDM trung tm s chia s thng tin trng thi v tng ca

n. Tuy nhin xu hng ny khng c tnh mm do v r rng l s xut hin cc tht

c chai cc b qun l NC&M ti c tng IP ln tng WDM. Xu hng tch hp ph

hp mt cch t nhin vi m hnh phn tn cho k thut lu lng. Ngha l mi im

u c kh nng khai thc iu khin tc nghn v thc hin n nh ti nguyn da

trn thng tin trng thi mng IP/WDM c lu tr cc b. M hnh phn tn ca k

thut lu lng nng cao tnh sn sng v tnh mm do nhng li phi i mt vi

kh khn l ng b ho phc tp gy ra bi bn cht ca quyt nh song song c

thc hin ti cc a im phn tn.M hnh chng ln M hnh tch hp

Trin khai tp trung TE chng ln tp trung TE tch hp tp trung

Trin khai phn tn TE chng ln phn tn TE tch hp phn tn

Bng 2.1 Cc m hnh trin khai TE

Tm li, xu hng chng ln s khng th thc hin mt cch hiu qu khi kch

c ca mng tng v cc my ch IP v WDM NMS u tr thnh cc tht c chai

tim tng. Xu hng tch hp s gp phi vn ln v phc tp ca trin khai.



31/112


ng b ho gia mt lng ln cc node IP/WDM v trng thi mng v thng tin

cu hnh i hi mt khong thi gian di hi t. La chn k thut lu lng

chng ln hay tch hp v m hnh trin khai tng ng ph thuc vo lu lng ng

dng v mng vn hnh. M hnh khi chc nng k thut lu lng c trnh by

trong n s bao qut c hai m hnh ca hai dng thc trin khai. Cc thnh phn

trong m hnh khi l chung cho cc ng dng k thut lu lng trong mng

IP/WDM.

2.6 M hnh chc nng ca k thut lu lng IP/WDM

C ch cho php c bn trong m hnh khi k thut lu lng l ng i ngn

nht v gim st ng i o theo nhu cu. Mt c tnh c nht v nh trong mt

mng WDM l kh nng ti cu hnh ng i ngn nht v m hnh o. iu c

ngha l i vi mt m hnh si quang vt l, mng WDM vt l c th h tr mt sm hnh o c hnh thnh t cc ng i ngn nht. Hnh 2.5 ch ra cc thnh phn

chc nng chnh ca mt m hnh khi k thut lu lng c kh nng ti cu hnh v

n bao gm cc thnh phn sau:

Khi gim st lu lng: thnh phn ny c nhim v thu thp cc s liu thng

k lu lng ( y l lu lng IP) t cc b chuyn mch v nh tuyn hay trn cc

tuyn truyn dn. h tr tnh nng ny, cc mng IP/WDM s gim st lu lng

IP.Khi phn tch lu lng: thnh phn ny s a ra cc quyt nh da trn cc

s liu thng k thu thp c. Mi khi c cp nht, b phn ny cng a ra cc bo

co phn tch.

Khi d on bng thng: thnh phn ny c s dng d on nhu cu

bng thng trong tng lai gn da trn cc c tnh lu lng v cc kt qu o kim

hin ti v trong qu kh.

Khi gim st hiu nng tn hiu: thnh phn ny c nhim v gim st QoS tnhiu quang ng vi mi knh bc sng. QoS tn hiu l mt tp hp phc tp ca cc

yu t ng lin quan ti nh tuyn bc sng v qun l li. Qun l li WDM khng

phi l nhim v chnh ca TE nn QoS tn hiu ch c s dng bi ti cu hnh

ng i ngn nht.

Khi khi to ti cu hnh k thut lu lng: thnh phn ny bao gm mt tp

hp cc quy nh. Cc quy nh ny s quyt nh khi no s ti cu hnh mc mng

nn c thc hin. Quyt nh ny c th da trn cc iu kin lu lng, cc d



32/112


on v bng thng v cc yu t vn hnh khc nh l gim thiu nh hng ca cc

thng s chuyn tip v m bo thi gian hi t mng ph hp.

K h i g i m s t l ul n g I P

K h i t h a m c h i u n h uc u b n g t h n g

K h i p h n t c h l u

l n g I P

I P/W D M t g i ih n d i c h a?

T i c u h n hm h n h o/ n g in g n n h t W D M

K h i g i ms t h i u n n g

t n h i u

K h i t i c uh n h n g i n g n n h t

D c h c h u y n

m h n h

C n b n g t i IP/M P L S(O M P)

T h i t k m h n h n g i n g n n h t

T h i t l p m t m h n h m i t t h n ?

K h u y n n g h c pn h t d u n g l n g

C p n h t

C p n h t

C p n h t

C

C h aT i c u h n h m h n h

n h g i

K h n g t h n h c n g

T h n h c n g

T i c u h n h n g in g n n h t

B o c oQ o S t n h i u

T i c u h n h n g i n g n n h t

T h i t l p Q o St n h i u

K h i t o

Hnh 2.5 M hnh khi chc nng k thut lu lng IP/WDMKhi thit k m hnh ng i ngn nht: thnh phn ny s tnh ton mt m

hnh mng da trn cc d on v kt qu o kim lu lng. Vic ny c th c

coi nh vic ti u ho mt s (cc b nh tuyn IP c kt ni bi cc ng i

ngn nht trong tng WDM) cho nhng mc tiu nht nh (v d nh l cc i ho

thng lng), tu theo cc iu kin rng buc c th (v d nh cp node, dung

lng giao din), i vi mt ma trn nhu cu cho trc (ngha l ti lu lng trn

mng). Tm kim mt s ti u yu cu lng tnh ton rt ln. Do vic thay i

kiu lu lng s khi to ti cu hnh nn mt s ti u ho c th s khng cn l

ti u ho na khi s ti cu hnh ca n hon thnh trong thc t. Mt xu hng thc

t hn l s dng cc thut ton kinh nghim. Chng ch tp trung vo cc mc tiu c

th chng hn nh hiu qu v mt chi ph, tc hi t v/hoc gim thiu nh hng

ln lu lng ang truyn thay v tm kim ti u ho ton cc.

Khi dch chuyn cu hnh: thnh phn ny bao gm cc thut ton lp thi

gian biu cho vic chuyn i cu hnh mng t cu hnh c sang cu hnh mi. Ngay

c khi cc ti nguyn tng WDM l h tr bt c dch chuyn no k tip (tt ccc kt ni mi u c th thm vo trc khi loi b cc kt ni khng cn thit) th



33/112


vn cn cc vn khc lin quan ti s dch chuyn. V d nh khi ti cu hnh

WDM i vi cc knh c dung lng ln (v d nh ln ti OC-192 trn mt bc

sng) th vic thay i n nh cc ti nguyn i vi cc lng ln nh th s c nh

hng ng k ln mt s lng ln lu lng ngi s dng. Mt th tc dch

chuyn bao gm mt chui cc thit lp v loi b tng ng i ngn nht WDM

ring r. Cc dng lu lng phi thch nghi vi cc thay i v ng i ngn nht

trong sut cng nh sau khi din ra mi bc dch chuyn.

Khi ti cu hnh ng i ngn nht: thnh phn ny c s dng ti cu

hnh cc ng i ngn nht ring l, ngha l thit lp v hu b ng. N li i hi

cc khi sau y:

Thut ton nh tuyn ng i ngn nht: dng tnh ton ng i

ngn nht. Khi tuyn ng i ngn nht l cha xc nh, thnh phn nys tnh ton ng i nh tuyn hin. Nu c sn mt giao thc nh

tuyn (v d nh giao thc OSPF vi cc m rng cho quang), ng i

nh tuyn c th ly ra t bng nh tuyn cc b .

C ch hu b/thit lp ng: dng thit lp hoc hu b mt tuyn

v n c th l mt gio thc bo hiu.

Qun l giao din: c nhim v giao din v cp nht cc thng tin lin

quan ti n. S ti cu hnh ng i ngn nht c th gn li cc giao

din khch WDM cho mt ng i ngn nht khc. iu s nh

hng ti giao din gia WDM v mng IP. nh tuyn IP i hi cc a

ch IP v ch cho php gi tin c chuyn tip trong mt mng con IP. V

th mt m hnh IP mi c th i hi cc thay i a ch giao din IP.

2.6.1 C s d liu thng tin trng thi mng IP/WDM

Mt c s d liu thng tin trng thi mng l cn thit iu khin v qun l

mng IP/WDM. Da trn m hnh k thut lu lng v xu hng trin khai n m c

s d liu thng tin trng thi mng (bao gm c TE) s c xy dng v duy tr

tng ng. V d nh, trong xu hng tch hp th mt c s d liu IP/WDM tch

hp ton b s phi c lu tr tt c cc im v s ng b gia cc c s d

liu s do mt giao thc phn tn m nhim; cn trong xu hng chng ln c s

d liu IP c lu tr ring r vi c s d liu WDM.

Thng tin trng thi mng m k thut lu lng quan tm bao gm hai mt: cc

ti nguyn v cch s dng chng. Cch biu din truyn thng cc ti nguyn mng

dng cho mc ch nh tuyn gi tin ch n gin l thng tin m hnh. Tuy nhin, kthut lu lng i hi nhiu thng tin hn th, v d nh bng thng tng cng v s



34/112


s dng ca mi kt ni hin thi. Tn ti hai tng nh tuyn trong mng IP/WDM

chng ln. Mt thc hin nh tuyn cc ng i ngn nht qua mng vt l, trong khi

tng cn li thc hin nh tuyn d liu trn cc ng i ngn nht y. C th thc

hin k thut lu lng trn c hai tng . K thut lu lng WDM khng ch quan

tm ti s tn dng cc ti nguyn mng m cn c ti cc c tnh quang ca cc kt

ni quang WDM v cht lng ca tn hiu. Khi s dng k thut lu lng chng ln,

cc chc nng mc tiu cc tng khc nhau c th khc nhau. Cn trong trng hp

ca k thut lu lng tch hp, iu khin lu lng v n nh ti nguyn c xem

xt ng thi do cc mc tiu ti u ho mang tnh kt hp.

Mc d cc m hnh k thut lu lng khc nhau i hi thit k v trin khai c

s d liu thng tin trng thi mng khc nhau, nhng c mt s thuc tnh chung cho

c hai trng hp. Trong xu hng chng ln, c s d liu thng tin trng thi mngca tng IP bao gm cc thng tin sau:

M hnh o IP: l mt s c hng trong cc nh biu din cc b nh

tuyn IP v cc cnh biu din ng i ngn nht. N ging vi cc i hi ca mt

giao thc nh tuyn trng thi tuyn ni tiu chun. Trong cng bao gm tc d

liu v cc khun dng tn hiu m mi giao din IP c th h tr. M hnh ny rt hu

ch cho vic thc hin cu hnh ng.

Trng thi tuyn ni IP: bao gm dung lng tuyn ni v s tn dng n (tnhtheo phn trm). N cng c th bao gm mt s kt qu o khc (v d nh s lng

gi tin b mt ti giao din b nh tuyn) cn thit cho cc thut ton k thut lu

lng.

Ti tng WDM, thc th c qun l l mng vt l, trong ti c th hin

bi cc vt ng i ngn nht. Ti tng ny hot ng ca k thut lu lng c

thc hin thng qua vic gn m hnh o IP vo mng vt l. Cc hot ng qun l

mng l gn bc sng v nh tuyn. Nu tnh lin tc bc sng l cn thit dc theomt vt th ch c gn mt bc sng duy nht; nu mt WDM NE c kh nng

chuyn i bc sng, cc hop khc nhau s c th s dng cc bc sng khc nhau.

Do vy, mt c s d liu thng tin trng thi mng ti tng WDM s bao gm cc

thnh phn sau:

M hnh vt l: l mt s c hng trong cc nh biu th cc WDM NE

v cc cnh biu th cc si quang.

Cc c tnh NE: biu th kh nng chuyn mch v sn sng ca cng. MtNE c th thc hin chuyn mch si (ngha l kt ni tt c cc bc sng trong mt



35/112


si u vo ti mt si u ra s dng cng bc sng) hoc chuyn mch bc sng

(ngha l kt ni mt bc sng c th trong si quang n ti cng mt bc sng

trong mt hoc nhiu si ra). Hn th, mt tn hiu c th c chuyn i thnh mt

bc sng khc thng qua chuyn i bc sng. Mt NE c s lng cng xen/tch

hu hn do c th c s tranh chp gia cc tn hiu xen/tch ti ma trn chuyn

mch.

Trng thi si: bao gm s lng bc sng, hng, loi bo v tuyn v cht

lng tn hiu quang v d nh tng cng sut bc sng ca si , ng k bc

sng, cng sut mi bc sng ring r, SNR quang ca mi bc sng.

Trng thi ng i ngn nht: bao gm NE ID ngun, ID cng xen, NE ID

trong tuyn, ID cng tch, ID bc sng (cho mi hop si) v hng ca n, tc

bit, SNR quang t u cui ti u cui, cc ID SRLG (nhm tuyn ni chia s nguy

him). Ngoi ra cn c th tu chn u tin ng i ngn nht hay mc lm

rng ng i ngn nht.

Trong k thut lu lng tch hp, m hnh bc sng v m hnh si c kt

hp lm mt. Ti u ho c thc hin da trn nh tuyn bc sng theo cc iu

kin rng buc si quang. Do vy, ni dung ca c s d liu tng IP v c s d liu

tng WDM trong m hnh chng ln trn s c ghp lm mt c s d liu thng

tin trng thi mng IP/WDM duy nht.

2.6.2 Qun l giao din IP vi WDM

iu khin mt cch hiu qu cc giao din gia IP v WDM l vn thit yu

thc hin k thut lu lng ph hp trn cc mng IP/WDM. Xu hng l phi li

dng cc c tnh phn cng m vn duy tr c tnh mm do v kh nng m rng

v hin nay phn cng mng ang xut hin mi rt nhiu. Hin ti, mt giao din IP

duy nht ch c th kt hp vi mt ng i ngn nht. iu ny lm cho mt mng

IP/WDM khng c g c bit hn mt mng IP trn nn bt c mt mng truyn dnknh o no. K thut lu lng ni ring hay qun l v iu khin mng ni chung,

i vi cc mng IP/WDM kiu ny, l m i vi tt c cc k thut hin ang tn ti,

pht trin.

Trong min phn mm, IP/WDM i hi phn mm tng ng qun l giao

din phn cng gia IP vi WDM v chuyn i gia lc a ch IP v a ch

WDM (khi cn thit). Trong xu hng chng ln cn c mt lc chuyn i a

ch duy tr nh x gia hai tng. Ch rng tng WDM cng c th s dng cc a

ch IP thay v cc a ch vt l nhng vn cn lc chuyn i a ch v tng IP v



36/112


tng WDM s dng hai khng gian a ch khc nhau v cc v d nh tuyn khc

nhau. Mt li ch ca xu hng chng ln l vic li dng cc c ch iu khin sn

c cho mng IP v mng WDM. Trong xu hng tch hp, mi giao din IP/WDM NE

c nh a ch IP. Do , ch c mt lc a ch c s dng m y l a

ch IP, v ch c mt kh nng nh tuyn m thi. Tuy nhin, cc giao thc IP truyn

thng nh l OSPF cn phi c m rng bao gm cc vn v kt mng

IP/WDM.

2.6.3 Khi to ti cu hnh

Nh c ch ra trong hnh 2.6 th ti cu hnh c th c khi to bi nhiu

yu t khc nhau, v d nh:

K thut lu lng

Li

Bo v/ti lp

Bo tr mng

B khi to li bao gm khi pht hin li, khi phn tch nguyn nhn v khi

qun l li. Mi khi mt li b pht hin v nguyn nhn gy ra n c xc nh, khi

qun l li s quyt nh vic cn lm. Phn mng b li c th b cch ly v cc kt ni

b nh hng s c nh tuyn li. B khi to bo v/ti lp c th c s dng

h tr ti cu hnh ng. Mi khi ng i chnh b hng, thut ton ti lp s tnhton (hoc tnh ton trc) mt ng d phng. Khi kt hp c nhim v chuyn

mch ng t ng chnh sang ng d phng. Cc c ch ti cu hnh cung cp

cc tin ch cho vic thit lp v hu b ng, ngha l mt giao thc bo hiu. Giao

thc bo hiu phn tn ng mt vai tr quan trng trong bo v/ti lp. Khi bo tr

mng lin quan ti vic lp thi gian biu cho cc hot ng vn hnh v thay th v

c th thc hin d dng hn nh s dng ti cu hnh.



37/112


Phn tch v gimst lu lng

Tham chiubng thng

Thut ton kthut lu lng

Phn tch nguynnhn li

Pht hin li

Qun l li

Khi to li

Khi to li

Thit k m hnh Qun l giaodin

Thut ton nh tuynng i ngn nht (v d

nh OSPF)

Giao thc bohiu

Dch chuyn mhnh

Khi kt hp

Thut ton ticu hnh

Khi to bo v/ti cu hnh

Lp thi gianbiu

Thay th

Khi to bo trmng

Khi to k thut lu lng (v d nh do nghn)

Hnh 2.6 Ti cu hnh trong mng IP/WDM

C ba thnh phn chnh trong c ch ti cu hnh: thit k m hnh, dch chuyn

m hnh v ti cu hnh ng i ngn nht. B phn ti cu hnh ng i ngn nht

li bao gm ba khi nh l qun l giao din, thut ton nh tuyn ng i ngn nhtv giao thc bo hiu. Khi c ch ti cu hnh s c khi ng khi t c cc

iu kin khi to nht nh.

2.6.4 o kim v gim st lu lng

Cc mng IP/WDM c dng phn pht lu lng IP. o kim lu lng

mng t c thng qua vic gim st IP v cc c ch thu thp l thit yu cho cng

vic ca k thut lu lng. chnh xc ca cc php o nh hng trc tip ln hiu

nng cng vic v cc kt qu o cung cp thng tin u vo m t cc iu kinmng ng. Trong mt vng kn ng, lin tc, cc php o lu lng mng c th

khi to thut ton ti cu hnh cng nh nh gi tc ng ca s ti cu hnh.

Cc s liu thng k cn phi thu thp ph thuc vo cc mc tiu ti u ho v

thut ton tm kim thng tin c s dng. V d nh, s lng lu lng l rt quan

trng khi mc tiu ti u ho l thng lng ton cc; tr mt hng gia mt cp

node cho trc l quan trng khi tr gia cp node l mc tiu ti thiu ho.

Tu thuc vo cc mc tiu k thut lu lng, o c lu lng v thng k tis phi c kh nng la chn mm do cc phn mnh trong mt tng th, ly mu v



38/112


o c. Phn mnh tng th lin quan ti phn cc u cui trong dng lu lng c

gim st. Ly mu ht yu cu mt lu lng ln cn phi gim st v vic x l cng

sut cc thit b. o kim ht xc nh khong thi gian m trong lu lng d liu

c tnh trung bnh. La chn hp l trong s cc ht trn cho php iu khin chi ph

vn hnh k thut lu lng. Cng vi cc thng k c sn trong cc SNMP MIB, tp

hp thi gian di ca cc kt qu thng k v phn tch chng cng rt quan trng

trong vic xc nh mt m hnh mi. Cc yu t quyt nh trong cc phn tch trn l

d liu lu lng tng ti tng IP i vo ma trn v vic d on nhu cu lu lng

trong tng lai gn.

Gim st lu lng v thu thp cc kt qu thng k khng phi l mt cng vic

n gin v lu lng l cc ln v dung lng ca cc ng trung k Internet hin

i l rt ln. Nu khng c quan tm mt cch cn thn, n c th lm gim ngk hiu nng mng. Hn na, cc c lng ma trn lu lng c th khng c sn

i vi hu ht cc thit b nh tuyn hin c trn th trng; trong khi cc ti tuyn

ni l c sn nhng n li khng cha thng tin c lng mt ma trn chp

nhn c.

Gim st lu lng bao gm cc nguyn tc sau:

S dng cc ma trn tiu chun

nh gi cc c tnh n hng S dng cc thit b chuyn dng cho cc php o chnh xc cao

o lin tc

Cung cp d liu hiu nng di hn

Cung cp truy nhp thi gian thc ti d liu hiu nng

Cung cp cc php o t u cui ti u cui

Cc phng php v cng c gim st lu lng

Kh nng gim st lu lng c th c trin khai ti mc gi hoc mc mng.Di y l mt s cc cng c phn mm c trn th trng cho php gim st lu

lng.

Gim st mc gi tin: phng php ny i hi phi gim st tt c cc gi tin,

v d nh l ti ngun gi tin. c bit, mo u gi tin c th c kim tra v cc

thng tin lin quan c th c trch ra t mo u. Hai cng c phn mm ph bin

cho vic gim st mc gi tin l:

tcpdump



39/112


Cng c ny s in ra tt c cc mo u ca cc gi tin trong giao din mng

tho mn biu thc boolean. N cng c th chy trong ch c w, khi

n s lu d liu gi tin vo mt tp tin c th phn tch sau ny v/hoc

chy vi c b, khi n s c ni dung t mt tp tin c lu thay v

c cc gi tin trong giao din mng. Trong tt c cc trng hp, ch c cc

gi tin tho mn biu thc mi c x l.

tcpdump cng c c c. Nu khng c c ny, n s tip tc bt gi cc gi

tin cho ti khi n b ngt bi tn hiu SIGINT hoc SIGTERM. Khi c c c,

n s bt gi cc gi tin cho ti khi n b ngt bi tn hiu SIGINT hoc

SIGTERM hoc mt s lng gi tin nht nh c x l. Cui cng, n

s bo co s lng gi tin qua b m v s lng cc gi tin ph hp vi

b lc ngha l cc gi tin ph hp vi biu thc la chn. libcap

y l th vin m c th c s dng bt gi cc gi tin xut pht t

card mng mt cch trc tip. N cung cp cc truy nhp khng ph thuc

vo hnh thc trin khai ti cc tin ch bt gi gi tin c s v tin ch ny

c cung cp bi cc h iu hnh. ng dng ca libcap c cc nh dng

c bn sau:

Ch nh giao din cn o c.

Khi to libcap. Libcap c th hot ng nh mt a thit b. Mi

php o c nhn dng bi mt b miu t lc (hay cn gi l nhn

dng phin).

Xc nh tp cc quy tc ch r loi lu lng no mun tm kim,

lin kt cc quy tc ny li v p dng chng cho phin.

Thc hin lp s cp tin hnh o.

ng phin hay b miu t lc.

Gim st mc mng: phng php ny gim st cc hot ng mc mng vd nh tc nghn mng v cc tht c chai hiu nng. Gim st mc mng c th c

thc hin theo ba cch: o tch cc, o th ng v gim st iu khin. Phng php

o tch cc s thc hin gi d liu qua mng v quan st kt qu. Trong khi

phng php o th ng s chn mt my d vo tuyn ni gia cc node trong mng

v s tng kt v ghi li cc thng tin v dng lu lng trn tuyn ni . Phng

php gim st iu khin s bt gi v phn tch thng tin iu khin mng chng hn

nh thng tin nh tuyn v qun l mng.



40/112


c bit, gim st mc mng c th thc hin nh vic s dng cc cng c da

trn Ping, d ng, SNMP, v cc thit b gim st mng. V d nh, c th s dng

Ping o thi gian phn hi tin trnh, t l tn tht gi, s bin thin ca thi gian

phn hi v s thiu kh nng phn ng (ngha l khng c phn ng cho mt lot cc

lnh Ping):

Cc cng c da trn Ping: cc cng c ny s dng cc php o v phn

tch lin quan ti lnh Ping c gi l PingER. Cc cng c ny c th

thu thp cc kt qu o tch cc nh cc bn tin ICMP (ting vng yu

cu/phn hi). Cc cng c ny gm c ba phn:

Khi gim st v tr: Khi ny c ci t v cu hnh ti v tr cn

gim st. D liu Ping thu thp c s lun sn sng cho cc my

ch nh HTTP. Cng c cc cng c PingER c kh nng gim st vtr m cung cp cc phn tch trong thi gian gn v bo co cc d

liu m n c trong cc b nh cache cc b.

Khi gim st v tr xa: Khi ny c ci t ti my ch xa th

ng. N gn vi t nht mt v tr gim st c th.

Khi nhn v phn tch v tr: Khi ny c th c t mt v tr

duy nht hoc thm ch mt my ch dnh ring hoc cng c th

c t tch ring nhau. V tr lu tr s thu thp thng tin nh s

dng HTTP t cc v tr gim st theo chu k thi gian nht nh. N

cung cp cc d liu thu thp c cho cc v tr phn tch, v sau

cung cp cc bn bo co ang c thng qua Web.

D ng: cng c ny in ra tt c cc hop trung gian gia mt cp

node ngun v node ch v o thi gian hnh trnh gia node ngun

v mi hop. D ng s dng trng IPv4 TTL hoc trng IPv6

hop limit v hai bn tin ICMP (ngha l thi gian tri khi truyn dn

v cng khng th tip cn). N bt u gi mt bn tin UDP tich vi mt TTL (hay l hop limit) bng 1. iu ny s bt b nh

tuyn hop u tin s tr li mt ICMP c thi gian tri trong

truyn dn mang gi tr li. N tip tc gi mt bn tin UDP ti node

ch nhng c gi tr TTL tng dn 1 n v. Cui cng, node ch s

nhn c bn tin UDP thm d v tr li mt ICMP cng khng tip

cn c khi bn tin UDP c nh a ch ti mt cng khng

s dng. Trong thit lp mc nh, n s gi ba bn tin UDP thm d

cho mt thit lp TTL. Do thi gian hnh trnh cho mi hop c th



41/112


c c lng bng trung bnh cng ca ba khong thi gian c

o .

SNMP: c th s dng SNMP thu thp cc php o cc b t cc

b nh tuyn IP.

Cc php o tuyn ni th ng: Xu hng ny i hi cc thit b

mng c bit nh l cc b phn tch giao thc hay OCX-mon. Mt

gim st OXC-mon l mt PC bng rnh chy trn h iu hnh Linux

hoc FreeBSD. Cng vi cc linh kin cho PC (400 MHz PII, 128

Mbytes RAM, 6-Gbyte SCSI disk), n cn c ci t hai card o v

mt b chia quang c s dng kt ni b gim st ti mt tuyn

ni quang OC-3 (155 Mb/s) hoc OC-12 (622 Mb/s).

nh ngha dng lu lng

Thut ng dng c s dng rt rng ri nhng vi rt nhiu nh ngha

khc nhau chng hn nh trong gim st QoS, nh tuyn QoS, chuyn tip gi. Mt

nh ngha chung cho mt dng lu lng trong k thut lu lng l rt quan trng

i vi tp hp d liu v i vi vic s dng cc kt qu thng k lu lng c

thu thp bi cc lc thu thp lu lng ca cc nh s dng dch v khc nhau.

Sau y l nh ngha dng cho o lu lng:

Tnh hng: Dng c th l n hng hoc song hng. Vi cc dngn hng, lu lng t A ti B v t B ti A c coi l cc dng lu

lng khc nhau trong khi thu thp v phn tch. D liu song hng cung

cp cc c im bn trong ca cc giao thc bao gm c cc vn c

th rt r rng trong cc mng ng trc nhng li kh nhn ra hn ti

cc u cui. R rng l d liu song hng l phc tp v lm tng

phc tp i vi cc thut ton k thut lu lng. cho n gin, gi

thit rng cc dng song hng khng c s khc bit so vi trng hp

hai dng n hng ca cng mt cp node. V d nh, ln lu lnghay tn dng ca mt dng song hng l ln hn ln lu lng

hay tn dng ln hn hai dng n hng. Hay, dng song hng c

th coi l bng vi mt trong hai dng n hng . Nu nh th th mt

dng song hng gia hai cp node c gi nh l lun lun i xng.

Cc im cui dng: im mu cht cho cc ch nh dng l cc im

cui ca dng. Chng m t cc thc th truyn thng. Cc dng c th

c coi l lu lng gia:



42/112


Cc ng dng: c nhn dng bi .

Cc my ch: c nhn dng bi .

Cc mng: c nhn dng bi . Lu lng chia s mt ng chung trn mng: c nhn dng bi

.

Tnh phn mnh dng: Mi dng gn vi mt phn mnh m c s ca

n l kch thc ca dng.

Tnh phn mnh mu ho gim st lu lng.

S hiu qu ca gim st lu lng lin quan ti tnh phn mnh gim st lu

lng. c tnh ny c th c ch nh trong thut ng tnh phn mnh mu ho vtnh phn mnh o c. Khi gim st mt mng, tn ti mt s tho hip gia chnh

xc ca vic gim st v phn mo u c gii thiu.

C hai xu hng gim st lu lng trong mt mng. Vic gim st c th chnh

l mt phn trong cc chc nng ca phn t mng c gim st, hoc vic gim st

c thc hin bi mt thit b dnh ring. D trong trng hp no th cng sut x l

cho php cng c th khng thc hin ton b nhim v gim st. Thay vo ,

vic gim st phi c thc hin theo mt phng thc mu ho. Nu iu ny xy

ra, ngi ta c th cn cc lut iu khin vic mu ho chng hn nh: ln

lu lng c s c th c c lng t cc mu thu thp c ti mt tc nh

Trong khi mt s thit b o hoc phn cng chuyn mch/nh tuyn u cui

tc cao c kh nng lin tc gim st cc dng lu lng th cc ng dng chng

hn nh lp k hoch dung lng, li khng cn mc chi tit nh th. Trong min

NSFNET, vin truyn thng ANS thc hin cc thc nghim trong vic mu ho

vi phn mnh l 1 trong 50 gi tin, 1 trong 100 gi tin v 1 trong 1000 gi tin.

dng cho vic lp k hoch dung lng th h pht hin ra rng mu ho vi tc 1trong N gi tin l chp nhn c vi gi tr N c ln trung bnh. Nhng tc

mu ho c 1 trong 1000 gi tin li b cho l qu ln c th tin cy cho vic lp k

hoch dung lng. Gi tr N l bao nhiu l ph hp cho ti cu hnh mc mng hay

v bn cht chnh l vic lp k hoch dung lng trong cc mng IP ngy nay cn cc

nghin cu b sung. Trong khi vi gi tr khong vi trm hoc nh hn l mt la

chn ban u tt th tt hn ht l tnh phn mnh mu ho c th thay i bi ngi

dng. y l mt c tnh quan trng, c kh nng thay i tho mn cc yu cu

v chnh xc o, cc c tnh lu lng v cng sut x l. Vic mu ho da trn



43/112


thi gian ngt l khng c khuyn khch v cc kt qu khng phn nh mt cch an

ton c tnh bng n ca lu lng.

Khi ti cu hnh mc mng l hng hiu nng (chng hn nh ti thiu ho tr

u cui ti u cui) th cc php o lin quan i hi gn nhn thi gian truyndn/thi gian n cho gi tin mt cch chnh xc. Cc la chn phn mnh mu ho

p ng cc yu cu ny bao gm:

Chn 1 trong N, trong mt gi tin ngu nhin khng nm trong N gi

tin k tip s c chn. iu ny lm gim s thin v xut hin trong d

liu qua qu trnh mu ho.

Chn cc gi tin lin tip nhau nghin cu thi gian n gia v

phn tch thi gian n ca cc gi tin.

La chn tt c cc gi tin t mt dng duy nht (dng ny c xc nht mt tng trn tng ng).

Mc d cn cc nghin cu su hn lin quan ti tc mu ho chp nhn c

v cc khong ngt tin tng c cho cc yu cu ng dng c th nhng ti nay mt

iu r rng l hai c tnh ca gim st lu lng cho mc ch ti cu hnh mc

mng l:

Tc mu ho c th cu hnh c

X l d liu khng trc tuyn

Tnh phn mnh o v ma trn lu lng

Cng vi tnh phn mnh mu ho, cn c vn v tnh phn mnh o. Mc

ch ca gim st l mt ma trn lu lng mng m nh c th d on c nhu

cu lu lng cho tng lai gn. Mt dng IP dnh cho mc ch ti cu hnh mc

mng bao gm dng lu lng n mt b nh tuyn bin c nh tuyn ti mt b

nh tuyn bin khc. Dng c c trng l vt thi gian ca cc byte/giy n dng

. Cc c ch nhn c vt thi gian ca mt dng lu lng s c trnh by phn di y. Vt thi gian ca dng lu lng c th bao gm tc byte trung

bnh trong dng lu lng trn mt khong thi gian cho trc.

Thng s o chnh cn quan tm cho ti cu hnh mc mng l ma trn ln

lu lng gia cc b nh tuyn bin trong mng IP/WDM. Nh vy vic cn lm l

xc nh VTP (i,j). N biu din ln lu lng loi P ang di chuyn t b nh

tuyn bin i ti b nh tuyn bin j trong mt khong thi gian trung bnh T. Do vy,

cc php o ny cung cp mt vt thi gian ca ln lu lng gia mt cp b nhtuyn bin cho mi kiu lu lng. T l thng s phn mnh o. N biu din s phn



44/112


tch thi gian ca cc vt lu lng. Cho trc VTP (i,j), m hnh mng IP, v thut

ton nh tuyn c s dng, ln lu lng yu cu cho mi tuyn ni IP trong

mt khong thi gian c th hon ton c xc nh.

Chng hn nh, dng lu lng c th c biu din bi mt vt thi gian baogm trung bnh trong 5 pht s byte/giy quan st c trn dng. Phn mnh thi

gian trung bnh (thng s T) chnh l khong thi gian php tnh trung bnh xy ra.

Trung bnh mn (trong khong thi gian c giy) l tt hn nhng do phi tho hip

vi kh nng o v mo u (thi gian x l b nh tuyn v khng gian nh cn dng

o) nn i hi phi gim thi gian trung bnh. Trung bnh th trong khong thi

gian di c th rt ra t trung bnh mn.

Mt cch l tng th mt khun dng xut php o ca b nh tuyn nn s

dng mt h thng trong mi gi tin xut ra c nh ch s m t ni dung

ca n v cc b nh tuyn c cu hnh vi cc du hiu cho php ngi s dng

c th ch nh cc trng d liu no h mun xut ra. Cng vo trong gi tin xut s

ch ghi cc trng c nhn dng bi ch s . Vic s dng ch s c th n gin

ho s thu thp dng v cung cp s mm do di dng s kt hp cc ng ch nh

khch hng v cc lc tng hp thay th. Trong thit k ti cu hnh mc mng,

ngi ta c th s dng mt ch s mt n bit thu thp cc php o. Mt n bit ny

chnh l mt tin t mng v n xc nh cc bit cho cc a ch IP v chiu di mt nmng ca cc mng cc b c gn vo mt b nh tuyn bin nht nh.

2.6.5 Gim st hiu nng tn hiu quang

Mt m hnh khi k thut lu lng tinh vi s thit k mng v m hnh da

theo cc nhu cu lu lng v tn dng cc ti nguyn mng tu theo kh dng ti

nguyn v cc iu kin rng buc QoS tn hiu. Trong mt chng mc no cc c

tnh tng quang nh hng ti vic quyt nh mc mng. Chng hn nh QoS tn

hiu c th gii hn s lng cc knh bc sng c h tr bi mt tuyn ni quang

v hn th na l tc d liu c h tr bi mi bc sng. Hn th, QoS tn hiu

quang cha ng cc yu t ng khng th c trong cc tn hiu in truyn thng.

Nu khng xem xt cc c tnh tng WDM th ch c th hi vng rng tng WDM

khng c mt iu kin rng buc ti nguyn no. Mt khi m hnh IP o (da trn

nhu cu lu lng) c to ra, gi s rng m hnh lun c h tr bng vic

s dng cc knh quang. Khi mun tnh ton nhiu tuyn i ngn nht ng thi t

c ti u ho th qu trnh s tr nn phc tp hn nhiu. Trong mt nn tng

IP/WDM tch hp, cc c tnh WDM quang nh vy cn phi c lin kt vi ccgiao thc iu khin IP thch ng. Mt mng WDM c th c h thng qun l li ca



45/112


ring n nhng n nn c tch hp cht ch vi iu khin IP. Nh th mng

IP/WDM tch hp vn cha ng nhng c tnh chnh ca IP l mm do v kh

nng thch ng.

Gim st hiu nng trong cc mng ton quang l qu trnh tn km, i hi vicchia tn hiu quang nh s dng cc thit b c bit hoc ti NE. Tuy nhin, sau khi

chia tch, tn hiu quang ban u b gim cht lng v do khong cch truyn dn

b gim nu khng c ti to tn hiu. Hin nay s ti to tn hiu min quang (chng

hn nh s dng cc b thu pht quang) l cha chn mui v rt tn km. V vy

trong thc t hin nay, gim st hiu nng cho cc mng ton quang theo mt m hnh

mm do vn l mt vn m. Trong cc mng quang O-E-O, QoS tn hiu tr nn

n gin hn v ti mi hop cc tn hiu quang li c ti to li.

2.7 K thut lu lng MPLS

IP cung cp mt gii php bin i tng i n gin trong cc gi tin c

chuyn tip trn tng on da trn thng tin ch phn tiu gi tin v bng nh

tuyn cc b. Mc ch ca k thut lu lng MPLS l ti u ho s tn dng ti

nguyn mng bng cch iu khin mt cch chnh xc cc dng lu lng trong min

nh tuyn ca n. la chn ng i, k thut lu lng MPLS c th c s

dng cho hai mc ch l cn bng ti v gim st mng:

Cn bng ti: c s dng cn bng cc dng lu lng trn mng giptrnh nghn, cc im nng v cc tht c chai. N c thit k mt cch c bit

trnh cc tnh hung trong mt vi thnh phn ca mng b s dng qu mc trong

khi cc thnh phn khc li khng c s dng ht cng sut.

Gim st mng: c s dng gim st mng mt cch ton cc.

2.7.1 Cn bng ti

Trong mt mng IP, nm gia cc node c th hnh thnh a ng cng chi ph.

Nu khng c s h tr ca nh tuyn hin hoc cn bng ti th mt ng s c

chn mt cch ngu nhin. Hnh 2.7 ch ra mt hin tng rt ph bin trong tt c

lu lng c chuyn tip dc theo mt ng. Kt qu l ng b nghn trong

khi cc ng khc c cng chi ph li vn ri. gii quyt iu ny, OSPF gii

thiu mt k thut l a ng ng chi ph (ECMP). K thut ny s phn b ti trn

a ng. C ba phng php c xut phn chia ti ln a ng ng chi

ph:

Chuyn tip gi tin theo vng trn: phng php ny thc hin chuyntip cc gi tin theo mt vng kn gia a ng. Chuyn tip vng trn



46/112


loi b s kt hp d liu hay s hnh thnh chui gi tin v do loi b

hiu nng thp TCP. Phng php ny ch p dng c nu nh cc tr

trong a ng l xp x nhau.

Phn chia cc tin t ch gia cc hop k tip sn sng: y l mt

phng php th gip trnh kt hp lu lng bng cch chia lu lng

da trn tin t trong a ch ch ca gi tin. Phng php ny c th p

dng vi mt WAN tc cao nhng cc tin t ngn l mt vn kh

khn v khi th phn ln cc gi tin s c nh tuyn ti mt tin t

duy nht.

Bm i vi mt cp ngun ch: phng php ny s dng mt hm

bm, chng hn nh CRC-16. N c p dng i vi a ch ngun v

a ch ch trong gi tin. Khng gian bm c phn chia u gia ccng sn sng bng vic thit lp cc ngng hay thc hin mt thut

ton modun. Nh vy, lu lng gia cp ngun v ch lun trong

cng mt ng. Phng php ny c th p dng cho cc WAN tc

cao.

Lu lng a cLu lng b c

Lu lng a c

Lu lng b c

B nh tuyn a

B nh tuyn b

B nh tuyn d B nh tuyn cRI RI

Hnh 2.7 Hin tng trn mng khi khng c cn bng ti

K thut lu lng MPLS phc tp hn ECMP t nht hai kha cnh. Th nht,

MPLS cung cp la chn ng ti u. V mt ton cc, ECMP ch c gng chia u

ti trn cc ng ng chi ph m khng c gng n nh cc dng mt cch ti u

cho a ng cng nh khng c hiu bit v sn sng v cc iu kin ti ng

ca a ng. K thut lu lng MPLS, thng qua c ch trn lt LSA m OSPF,

xy dng v duy tr mt c s d liu k thut lu lng. C s d liu ny cha thng

tin k thut lu lng lin quan ti mi tuyn ni v bng thng tng, bng thng sn

sng, bng thng t trc v bng thng c th t trc. Da trn c s d liu k

thut lu lng, k thut lu lng MPLS c kh nng thc hin n nh dng ti u

trong mt mi trng mng ng. R rng l mt phn chia ti ng u cho a ng

cha hn lun lun l ti u. V d nh, mt phn ca mt ng ng chi ph b quti trm trng trong khi cc ng khc ch qu ti nh hoc thm ch l ri. Mt c



47/112


ch cn bng ti ti u nn gn cc dng lu lng cho cc ng theo t l ngc vi

lu lng c s dng trong ng . IETF OSPF-OMP (a ng ti u)

khuyn ngh trin khai cc LSA m LSA_OMP_LINK_LOAD v

LSA_OMP_PATH_LOAD. LSA m LSA_OMP_LINK_LOAD bao gm cc thng

tin sau:

Ti tuyn trong mi hng c o bng mt phn ca dung lng tuyn.

Tc mt gi tin ph thuc vo trn dng hng i trong mi hng.

Dung lng tuyn c th hin di dng kB/s.

LSA m LSA_OMP_PATH_LOAD bao gm cc thng tin sau:

Ti ln nht trong mt hng t ngun ti ch c biu din nh l mt

phn ca dung lng tuyn. Cn ch rng tuyn c ti cao nht cha

chc l tuyn c dung lng sn sng thp nht.

Tng gi tin b mt trong mi hng t ngun ti ch ph thuc trn

dng hng i. N c th tnh theo cng thc sau:

( ) =links

linkpath LL 11

trong Lpath l tc mt gi cho ng v L link l tc mt gi cho mi tuyn

trn ng.

Dung lng tuyn nh nht trn ng trong mi hng t ngun tich.

iu chnh ti ng cn bng mt cch chnh xc, OSPF-OMP cng nh

ngha ti tng ng v phn c ti quan trng. Ti tng ng xut pht t vic

s dng ti phn mnh thc t c ghp knh bi mt thng s c lng da trn

mc tn tht nht nh theo TCP c hi vng l gim xung trnh tc

nghn. i vi mi tp a ng, phn ca ng c ti tng ng cao nht c

coi l phn ti quan trng. Hn na, mi ng trong mt cu trc hop k tip nmgi ba bin sau: chia s lu lng, s gia bc v m bc. C ch OSPF-OMP iu

chnh ti ca mi ng theo cch sau:

S gia bc ca ng s khng i nu ng cha phn ti quan trng

Nu ng khng cha phn ti quan trng nhng phn ti quan trng

thay i th ng s cha cc phn ti quan trng trc . ng

s c iu chnh nh sau:

S gia bc c thit lp gi tr thp nht trong s cc ng cha

phn ti quan trng.



48/112


Thit lp s gia bc bng mt na gi tr ban u.

Nu ng khng cha phn ti quan trng v ng khng

cha phn ti quan trng trc cng nh phn ti quan trng cha

thay i th s gia bc s c tng.

Hnh 2.8 miu t mt v d cn bng ti s dng OSPF-OMP, trong ti b

nh tuyn d, lu lng n b nh tuyn cc c chia ra hai ng sn sng. Bng

cch p dng mt hm bm i vi cp ngun v ch ti b nh tuyn d, lu lng

t a ti c c chuyn tip trn mt ng trong khi lu lng t b ti c c gn cho

mt ng khc.

B nh tuyn c

B nh tuyn a

B nh tuyn b

B nh tuyn d

Lu lng a c

Lu lng b c

Lu lng b c

Lu lng a c

Hnh 2.8 OSPF-OMP

So vi ECMP, k thut lu lng MPLS cung cp kh nng nh tuyn ng

hin. Kt qu l, k thut lu lng MPLS c kh nng tnh ton v thit lp cc LSP.Chng c th thay i hon ton tnh cht ca chuyn tip lin k. Trong trng hp

cc mng cha tn dng ht ti nguyn th cc quyt nh nh tuyn s c quyt

nh ch yu bi vic gim thiu tr. Trong cc mng tn dng ht ti nguyn th cc

quyt nh nh tuyn phi xem xt ti cc tuyn ni dung lng nh v cc tuyn ni

chu ti trng ln. Nh c cn bng ti s tn dng mng s c ti u. Tuy nhin,

khi s tn dng pht trin hn, vic cn bng ti bng cch iu chnh chi ph tuyn

ni s khng cn ph hp na v khi mng t hoc gn t dung lng ti a

ca n. MPLS-OMP s dng cng mt c ch cn bng ti nh trong OSPF-LMP. Skhc bit gia hai c ch ny nm kh nng ca MPLS trong vic thit lp/loi b

LSP. Bng cch tng cc knh p ng s pht trin lu lng, k thut lu lng

MPLS hi vng s trnh c cc im nng hay nghn cc i ho s tn dng hay

thng lng mng. T quan im li vo, mi khi mt LSP c thit lp, LSP tip

cn c li ra tr thnh mt lng ging o v tnh trng ti ca n c thit lp mt

cch tng ng. Nu c a ng gia hai node (li vo v li ra), ti c chia ra

cc ng . Nh th cc ng cha c tn dng c th b xo khi chuyn tip

lin k.



49/112


B nh tuyn a

B nh tuyn b

B nh tuyn d B nh tuyn c

Min MPLS

LSP

Lu lng a cLu lng a c

Lu lng b c

Lu lng b c

Hnh 2.9 MPLS-OMP

Hnh 2.9 miu t mt v d ca cn bng ti s dng MPLS-OMP, trong b

nh tuyn d l mt b nh tuyn li vo MPLS v khi to mt LSP t b nh tuyn

d ti b nh tuyn c. Mt khi LSP c thit lp, chuyn tip lin k (ngha l cu

trc hop k tip) s c cp nht ti b nh tuyn d sao cho b nh tuyn c tr thnh

b nh tuyn o lin k vi n. Bng cch thu thp ti ng LSP, LSP ny c cu

hnh khng ch mang lu lng xut pht t node b. Theo cch ny, lu lng c

phn b da trn sn sng v dung lng ca ti nguyn. Ch rng v d ny

khng c nh ch ra s nht thit b sung mt LSP. N ch th hin n nh dng

theo phng php MPLS-OMP.2.7.2 Gim st mng

K thut lu lng MPLS cng c th c s dng gim st mng bng cch

s dng lp k hoch mng di hn hoc tng i ngn hn. Thng qua thit lp/hu

b LSP ng, k thut lu lng MPLS c th h tr rt nhiu loi ng dng khc

nhau t VPN tnh v VPN ng ti LAN o. Cc LSP o c th c ci t hoc loi

b da trn s phn b lu lng o c. Hai nhim v ca k thut lu l

Documents

ki thuat luu luong IP-WDM