CĐ TTQ_GMPLS

8/3/2019 C TTQ_GMPLS

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Chuyn Thng Tin Quang nh Tuyn Trong Mng GMPLS

MC LC

MC LC ..............................................................................................................................1

DANH MC HNH V .........................................................................................................2DANH MC BNG BIU ....................................................................................................2DANH MC T VIT TT .................................................................................................3LI NI U ....................................................................................................................... 5CHNG I: TNG QUAN V GMPLS .............................................................................6

1. 1 Gii thiu GMPLS ...................................................................................................... 61.2 Cc giao thc nh tuyn trong GMPLS .....................................................................9

1.2.2 Giao thc bo hiu RSVPTE, CRLDP ..............................................................91.2.3 Giao thc qun l ng LMP ........................................................................... 10

CHNG II MT S VN CA MNG GMPLS .................................................... 112.1 Tnh chuyn hng a dng ....................................................................................... 122.2 Tnh chuyn tip a dng ........................................................................................... 122.3 Cu hnh ..................................................................................................................... 13

2.3.1 Nhn xut ........................................................................................................132.3.2 LSP hai hng ..................................................................................................... 142.3.3 Tnh m rng ....................................................................................................... 142.3.4 Cu hnh LSP ...................................................................................................... 152.3.5 C ch b ng ................................................................................................. 16

2.4 tin cy ................................................................................................................... 172.5 Mt s vn tn ti trong mng GMPLS ................................................................ 18

2.5.1 Bo mt ................................................................................................................19

2.5.2 H thng qun l mng ....................................................................................... 20CHNG III NH TUYN TRONG MNG GMPLS .................................................... 213.1 nh tuyn ng ngn nht ...................................................................................... 213.2 K thut nh tuyn li nhanh .................................................................................... 253.3 D phng trong GMPLS ............................................................................................ 263. 4 nh tuyn khi phc m bo cht lng ............................................................... 28

3.4.1 Nguyn l v hot ng u tin ......................................................................... 283.4.2 Thut ton nh tuyn trc tuyn m bo cht lng trong MPLS .................. 293.4.3 Thut ton nh tuyn khi phc ng ................................................................ 30

3.5 K thut lu lng trong trong GMPLS .................................................................... 30Gii thiu ...................................................................................................................... 30

3.5.2 Vai tr ca MPLS ................................................................................................ 313.5.3 nh tuyn trn c s rng buc: thnh phn chnh cho xy dng lu lng ... .32

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DANH MC HNH V

Hnh 1.1: Cu trc ngn giao thc GMPLS.........................................................................10Hnh 2.1: C ch chuyn tip k cn...................................................................................15Hnh 2.2: Cu hnh mng....................................................................................................16Hnh 2.3: Qu trnh thc hin qun l h hng trong mng GMPLS.................................17Hnh 2.4: C ch phc hi h tr bi mng GMPLS..........................................................18Hnh 3.1: Cc thit b cho DBR framework c s..............................................................24Hnh 3.2: Nguyn l nh tuyn trn c s rng buc.........................................................32

DANH MC BNG BIU

Bng 1.1: Chc nng thc hin trong GMPLS......................................................................8Chc nng thc hin ca cc giao thc GMPLS cho php qun l v iu khin cc hhng trn mng mt cch t ng. Khi xy ra h hng ti mt phn mng no thi n sc pht hin, nh v v cch ly vi cc phn mnh mng khc. y l mt im quantrng khi thc hin cc LSP t u cui ti u cui bng phng thc ng hm qua ccLSP c cu hnh cao hn. Cc bc thc hin cn thit qun l mt h hng (xc nh,

nh v, cch ly v phc hi c th hin trong)................................................................17

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DANH MC T VIT TT

ABR Area Boundary Router B nh tuyn vng bin

ATM Asynchronous Transfer mode Kiu truyn ti ng b

ASBR AS Boundary Router B nh tuyn bin AS

BGPBorder Gateway Protocol

Giao thc gateway bin

BDR Backup Designated Router B nh tuyn c c dphng

CIDRClassless Internet domain Routing nh tuyn tn min khng

phn lp

CBRConstraint Based Routing nh tuyn da trn c s

rng buc

DWDM Dense Wave Division MultiplexingGhp knh phn chia theo

bc sng cht

FTPFile Transfer Protocol

Giao thc truyn file

GMPLSGeneralized Multiprotocol LabedSwitching

Chuyn mch nhn a giaothc tng qut

ICMP Internet Control Message Protocol Giao thc bn tin iu khinlin mng

IETF Internet Engineering Task ForceNhm c trch k thutInternet

IGMP Internet Group ManagementProtocol

Giao thc qun l nhm linmng

IPInternet Protocol

Giao thc Internet

IS-IS Intermediate System to IntermediateSystem

H thng trung gian n hthng trung gian

FSC Frame Check Sequence Trng kim tra khung

LSP Lable Switched Path ng chuyn mch nhn

LANLocal Vng Network

Mng ni vng

LMPLink Management Protocol

Giao thc qun l knh

MPLSMulti Protocol Label Switching Chuyn mch nhn a giao

thc

MOSPF Multicast OSPF a phng OSPF

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OSPF Open Shortest Path First Giao thc u tin ng ingn nht

OSIOpen System Interconnection Kt ni cc h thng m

OXC Optical Cross-connector B u ni cho quang

RIP Routing Information ProtocolGiao thc thng tin nhtuyn

LSR Lable Switching Router B nh tuyn chuyn mchnhn

QoSQuality of Service Cht lng dch v

RARP Reverse Address Resolution

Protocol

Giao thc phn gii a ch

ngcRSVP Resource Reservation Setup

ProtocolGiao thc thit lp v lu trti nguyn mng

SPF Shortest Path FirstGiao thc u tin ng utin ngn nht

TETraffic Engineering K thut lu lng

TCP Transmission Control ProtocolGiao thc iu khin truyndn

WDM Wave Division Multiplexing Ghp knh phn chia theobc sng.

SDH Synchronous Digital HierrachyH thng phn cp ng b

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LI NI U

Hin nay p ng c nhu cu bng thng cho cc ng dng dch v th mng

truyn ti ch yu s l cc h thng truyn dn trn si quang. S a dng v phc tp

trong qun l cc phn t mng ti cc phn lp mng khc nhau l nhn t c bn

thuc y vic nghin cu giao thc GMPLS thng nht qun l gia cc thc th

mng khng ch phng thc chuyn mch gi m trong lnh vc chuyn mch thi

gian, khng gian qun l ng thi m rng chc nng h tr giao thc IP iu

khin thit lp hoc gii phng cc ng chuyn mch nhn LSP cho mng hn hp

bao gm c chuyn mch gi, chuyn mch knh, mng quang.Trong cc mng vin thng, vic truyn ti c n nh v hiu qu th nh tuyn

l mt trong nhng vn mu cht. T nhng l do trn, trong chuyn Thng Tin

Quang chng em chn ch nh Tuyn Trong Mng GMPLS. Chuyn

gm cc ni dung chnh nh sau:

Chng I : Tng qut v GMPLS

Chng II: Mt s vn ca mng GMPLS

Chng III: nh tuyn trong mng GMPLS

Sau khi hon thnh chuyn ny, chng em s c nhng hiu bit nht nh v

mng chuyn mch nhn a giao thc tng qut. T lm tin tm hiu cc

cng ngh mi.

Thay mt nhm em xin chn thnh cm n thy Hong Vn V tn tnh hng dn

chng em la chn v hon thnh ti ny.

H Ni ngy 20 thng 9 nm 2011

Sinh vin

Bi Tun Anh

Trn Tun Dng

Nguyn Th Hoa

Th Minh Tm

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CHNG I: TNG QUAN V GMPLS

1. 1 Gii thiu GMPLSCng ngh chuyn mch nhn a giao thc tng qut GMPLS (Generalized

Multiprotocol Labed Switching) l bc pht trin theo ca cng ngh chuyn mch

nhn a giao thc MPLS (Multiprotocol Labed Switching). GMPLS thc cht l s

m rng chc nng iu khin ca mng MPLS, n cho php kin to mt phng iu

khin qun l thng nht khng ch lp mng m cn thc hin i vi cc lp ng

dng, truyn dn v lp vt l.

Vic to nn mt mt phng iu khin thng nht i vi cc lp mng ha hn

kh nng to ra mt mng n gin v iu hnh v qun l, cho php cung cp cc kt

ni t u cui ti u cui, qun l ti nguyn mng mt cch hon ton t ng v

cung cp cc mc cht lng dch v (QoS) khc nhau cc ng dng trn mng.

Xu hng pht trin mnh m vic xy dng cc h thng truyn ti quang trong c

s h tng mng vin thng quc t ni chung, ca quc gia v cc nh cung cp dch

v mng ni ring phn no p ng nhu cu rt ln v bng thng truyn ti chocc ng dng mi trn mng, chng hn nh ng dng mng lu tr, thu bng thng,

cp nht d liu trc truyn trong c s h tng mng truyn ti a dch v.

Hin nay ngi ta cho rng p ng c nhu cu bng thng cho cc ng dng

dch v th mng truyn ti ch yu s l cc h thng truyn dn trn si quang vi cc

thit b ghp tch lung ADM, thit b ghp bc sng quang WDM, thit b u cho

lung quang OXC... S a dng v phc tp trong qun l cc phn t mng ti cc

phn lp mng khc nhau l nhn t c bn thuc y vic nghin cu ci tin b giao

thc MPLS thnh GMPLS khng ngoi mc ch thng nht qun l gia cc thc th

mng khng ch phng thc chuyn mch gi m MPLS thc hin m cn c

trong lnh vc chuyn mch thi gian, khng gian qun l. GMPLS cn m rng chc

nng h tr giao thc IP iu khin thit lp hoc gii phng cc ng chuyn

mch nhn LSP cho mng hn hp bao gm c chuyn mch gi, chuyn mch knh,

mng quang.

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Mt trong nhng yu t kinh t ni bt ca GMPLS l n c chc nng t ng

qun l ti nguyn mng v cung ng kt ni truyn ti lu lng khch hng t u

cui ti u cui. Vic cung ng kt ni cho khch hng theo kiu truyn thng nh

i vi mng truyn ti Ring SDH c c im l mang tnh nhn cng, thi gian p

ng di v chi ph kt ni cao. thit lp c kt ni t u cui n u cui theo

phng thc nhn cng ni trn ngi ta cn phi xc nh cc vng ring SDH no

trong mng m ng kt ni i qua, dung lng cn li ca vng ring cn

kh nng phc v khng, nu nh cha thi cn phi tm ng vu hi qua vng ring

no khc? Sau khi xc nh c ng kt ni ngi ta phi thng bo cho ton b

cc nt mng thuc cc vng ring thc hin cc thit lp lung hoc u chuyn

nhn cng trong cc vng ring, cng vic ny i hi rt nhiu nhn cng v tn rt

nhiu thi gian trao i thng tin nghip v. Cng ngh GMPLS cho php cc nt

mng t ng cung cp cc kt ni theo yu cu do vy gi thnh chi ph cung cp kt

ni cng nh gi thnh qun l bo dng gim i rt nhiu, thi gian cung ng kt ni

cung cp dch v gim i rt nhiu so vi phng php truyn thng (tnh theo gi

hoc pht so vi tun hoc thng ca phng thc nhn cng truyn thng).

S pht trin MPLS hng ti GMPLS.

Trong nhng nm tr li y, t chc IETF tp trung hng pht trin cc giao

thc MPLS h tr cc phn t mng chuyn mch hot ng bi cc phng thc khc

nhau nh theo thi gian, theo bc sng (DWDM), khng gian (OXC) thnh cc

chun ca giao thc GMPLS. N cho php mng GMPLS xc nh v cung ng kt

ni trn mng mt cch ti u theo yu cu lu lng ca ngi s dng v c khnng truyn ti thng sut trn mng IP v sau l truyn xung cc tin ch truyn

dn quang lp di nh l SDH, bc sng trong h thng DWDM trn mt si

quang c th no . Bng di y cho ta mt ci nhn tng quan nht v cc chc

nng thc hin trong GMPLS.

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Min chuyn

mch

Kiu lu

lng

Lc

chuyn tipThit b mng Thut ng

Gi, t bo IP, ATMNhn hay phntiu , kt ni

knh o (VCC)

B nh tuynIP, chuyn

mch ATM

Kh nngchuyn mch

gi (PSC)

Thi gian TDM/SONE

T

Khe thi gian

lp theo chu k

H thng u

cho s (DCS),

ADM

Kh nng ghp

knh TDM

Chiu di bc

sng Trong sut Lambda DWDM

Kh nng

chuyn mch

Lambda LSC

Khng gian

vt l

Trong sut Si quang, cp

ng

OXC Kh nng

chuyn mch

quang FSC

Bng 1.1: Chc nng thc hin trong GMPLS

Mt trong nhng im hp dn nht ca GMPLS l s thng nht v giao

thc iu khin thc hin thit lp, duy tr v qun l k thut lu lng theo

ng xc nh t im u n im cui mt cch c hiu qu. Dng lu lng

ca ngi s dng bt u t im ngun c th c truyn ti qua nhiu phm vi

mng. V d, lu lng theo nhiu loi hnh truy nhp khc nhau ca nhiu ngi

s dng c tp trung tch hp ti mt nt mng truy nhp hoc nt mng bin v

sau c truyn ti vo nt mng th theo cng ngh SDH hoc cng nghATM...Cc lung lu lng t mng th ny ny li c tp trung tch hp mt

ln na a ti mng ng trc bng bc sng mang lu lng, trn hng

truyn ngc li cng thc hin vi phng thc tng t. Nh vy vic thc hin

truyn ti lu lng nh ni trn qua rt nhiu cc tin ch truyn ti khc

nhau, s dng cc cng ngh khc nhau, do vy nu nh thng nht c v mt

iu khin, qun l, x l lu lng th s l mt u im tuyt i trong vic

truyn ti lu lng v qun l s dng ti nguyn hiu qu, cung ng dch v

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mng nhanh chng. ng thi, l nhng mc tiu thc hin m GMPLS hng

ti.

1.2 Cc giao thc nh tuyn trong GMPLS

S th hin chuyn i t MPLS sang GMPLS l cc giao thc m rng cho

chc nng bo hiu (RSVPTE, CR LDP) v chc nng nh tuyn (OSPFTE,

ISISTE). Nhng giao thc m rng ny l s b sung thm cc chc nng cho

cc phn t mng TDM/SDH v mng truyn ti quang ni chung.

Mt giao thc mi l giao thc qun l ng LMP (Lin kt-Management

Protocol) c xy dng thc hin qun l v duy tr tnh trng iu khin

cng nh trnh trng truyn ti lu lng gia hai nt k cn trong mng GMPLS.LMP l mt giao thc thc hin trn IP, n bao gm cc chc nng thc hin

RSVP-TE v CR-LDP.

1.2.1 Giao thc nh tuyn OSPF-TE v IS-IS-TE

L cc giao thc t ng xc nh cu hnh t-p mng, thng bo ti nguyn

kh dng (v d nh bng thng hoc loi hnh bo v...). Cc im ch yu ca cc

giao thc ny l: thng bo v loi hnh bo v ng (1+1, 1:1, khng bo vhoc lu lng ph), thc hin tm ng (gia cc nt mng k cn) nng cao

kh nng xc nh tuyn thng) m khng cn phi thc hin cc giao thc nh

tuyn trn c s a ch IP.

1.2.2 Giao thc bo hiu RSVPTE, CRLDP

Cc giao thc bo hiu thc hin k thut lu lng gia cc LSP. Nhng

chc nng ni bt ca cc giao thc bo hiu ny l: chuyn giao lu lng bao

gm c loi hnh lu lung khng phi dng gi, thc hin bo hiu hai chiu

gia cc LSP xc nh tuyn d phng cho trng hp bo v, thc hin gn

nhn cho phng thc chuyn mch nhn bc sng ngha l cc bc sng cn

k nhau c chuyn mch theo cng mt hng.

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1.2.3 Giao thc qun l ng LMP

Thc hin 2 chc nng chnh. Qun l knh iu khin: m bo vic thc hin

theo c ch m phn thng qua cc tham s ng thng (chng hn nh s dng

phng thc gi c chu k cc bn tin truy vn thi gian sng ca gi tin) m

bo tnh trng ca ng thng lun c theo di. Kim tra cc kt ni trn mng:

nhm duy tr hot ng ca cc kt ni gia cc nt mng k cn nhau thng qua

cc gi tin kim tra.

Hnh 1.1: Cu trc ngn giao thc GMPLS

Trong GMPLS, cu trc ngn giao thc cho chc nng nh tuyn ISISTE cngtng t nh i vi chc nng nh tuyn OSPFTE, ch c mt im khc l

thay lp nh tuyn IP bng chc lp nh tuyn phi kt ni CLNP (Connectionless

Network Protocol) s dng truyn ti thng tin theo giao thc ISIS-TE.

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CHNG II MT S VN CA MNG GMPLS

Trong mng GMPLS c mt s vn cn quan tm.

Vic chuyn tip d liu khng n thun hn ch chuyn tip d liu dng

gi m cn cn phi tm kim cc gii php n gin nht cho vic s dng mt

khun dng nhn duy nht chuyn tip d liu qua cc loi thit b vi cng ngh

khc nhau theo phng thc chuyn tip theo thi gian, bc sng hoc khng

gian.

Khng phi loi mng no cng thit k cc phn t chuyn tip d liu cho php

truy vn ni dung thng tin, nhn hoc mo u ca d liu thu c. Mng chuyn

mch gi cho php cc phn t chuyn tip ca mng kim tra mo u gi hoc

nhn t a ra cc quyt nh d liu s c chuyn tip ti giao din u ra c

th. Trong khi iu ny s khng thc hin i vi lung d liu u vo l cc

d liu dng TDM (c th l cc lung ghp knh PCM, hoc l bc sng).

Tnh cn i v ph hp l mt vn quan trng khi thit k nhng mng cln. Thng thng ti nguyn cn phi qun l trong mng TDM v mng quang

ni chung l nhiu hn rt nhiu so vi mng chuyn mch gi. V d, s lng

bc sng cn phi qun l trong mt mng quang c th ln ti hng ngn v s

lng si c th ln ti hng trm.

Cu trc ca ca cc b chuyn mch quang hoc in cng l phn t gy ra s

tiu tn thi gian x l d liu. V d mt thit b DSC c kh nng chuyn mch t

hng chc ti hng ngn cng cho ng tn hiu s (DS-x), vic xc nh cng vo

cng ra cho mt kt ni cng tiu tn kh nhiu thi gian, iu ng ngha vi

vic gia tng ca phn t chuyn tip, ngha l tng tr truyn ti d liu.

Mng SDH c kh nng rt tt trong vic thc hin c ch bo v ng truyn

ti d liu (50ms). H thng qun l iu khin mng thc hin trong GMPLS cng

cn phi thc hin chc nng bo v ng truyn ti tng t nh SDH, c th

theo phng thc ci t trc, c ch ng, c ch u tin theo lp dch v.

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2.1 Tnh chuyn hng a dng

GMPLS c pht trin m rng c kh nng h tr cc phn t mng truyn

ti thng tin t u cui ti u cui thng qua nhiu mng vi cc cng ngh khc

nhau vi tc x l truyn ti nhanh. thc hin c iu ny trong cng ngh

GMPLS, ngi ta chn thm thng tin trong cc nhn MPLS. nh dng mi ny

ca nhn c gi l "nhn tng qut" (Generalized Label) cho php cc thit b thu

nhn d liu cc dng ngun khc nhau (nh l gi tin trong mng chuyn mch

gi, cc khung ghp knh d liu trong mng TDM, bc sng mang d liu trong

mng truyn ti quang...). Mt nhn tng qut c th i din cho mt bc sng,

si quang n l hoc mt time-slot, ngoi ra n cn i din cho d liu ca cc

ngun lu lng khc thc hin vi nhn MPLS nh l VCC trong ATM, phn

gn thm (shim) trong gi tin IP... Cc thng tin sau y gn lin vi nhn tng

qut:

- Dng ca m LSP ch th loi nhn mang lu lng ( v d: gi tin, bc sng,

SDH...)

- Loi hnh chuyn mch, ch th cho nt mng khi no s thc thi cc loi hnh

chuyn mch khc nhau: chuyn mch gi, chuyn mch knh, chuyn mch bc

sng, chuyn mch si quang.

Tng t nh MPLS, s phn b nhn c khi u t vic yu cu phn b nhn

t ng ln i vi ng xung ca LSR. GMPLS thc hin bng cch cho php

ng ln ca LSR xut trc gi tr ca nhn cho mt LSP v gi tr nhn nyc th c thay th bng gi tr nhn gi tr li t ng xung ca LSR.

2.2 Tnh chuyn tip a dng

GMPLS thc hin m rng tnh nng ny cc thit b GMPLS c th nhn bit

mi loi mo u m chng thu c. Trng hp ny GMPLS cho php mt

phng iu khin v truyn ti c th tch ri nhau khng nhng v mt lgc m

cn c th tch ri v vt l. V d, thng tin iu khin ng iu khin gia ntmng c th truyn theo knh kt ni Ethernet hoc qua cc tin ch truyn dn khc

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m n khng cn quan tm vic thng tin qun l gia hai nt mng c truyn ti

bng cch no.

Vic la chn tin ch truyn ti thng tin iu khin gia cc nt mng GMPLS

l rt c ngha v mt kinh t. R rng l khng nn s dng si quang ring bit

truyn thng tin iu khin gia cc ADM trong mt mng ring SDH no .

Thay vo chng ta c th tip cn gii quyt vn theo mt cch khc, mt

trong nhng cch l s dng nhng byte thng tin mo u cn trng trong

khung SDH truyn cc thng tin v iu khin. Vi mo u trng trong khung

STM-1 chng ta c th tn dng c mt dung lng knh truyn ti 768 kbit/sec

trao i thng tin iu khin gia cc nt mng. Phng php ny c rt nhiu

u im v c tnh kh thi cao.

2.3 Cu hnh

Khi mt LSP cn c to lp khi u t phm vi mng truy nhp,n yu cu

thit lp mt vi LSP khc dc theo tuyn t nt u ti nt cui. Cc LSP trung

gian c th c to lp trong qua cc thit b TDM hoc LSC. Cc thit b ny c

th c nhng c im ring khc nhau do vy chc nng GMPLS cn phi thng

nht c cc c tnh khc nhau to lp cc LSP t u cui ti u cui.

2.3.1 Nhn xut

Mt ng ln ti nt mng c th la la chn mt nhn xut vi ng

xung ca n. ng xung c quyn t chi cc tham s kin to LSP do nhn

xut a ra v xut cc tham s ca mnh. Nhn xut trong trng hp ny

cn c s dng tm ng bn trong t ca vo ti ca ra mt cch nhanh

chng. Nhn xut cho php cc DCS t nh cu hnh ca mnh bng nhn

ngh (Proposed Label) thay v ch nhn a li t hng ngc li trn ng

xung. Nhn xut ng vai tr quan trng trong vic thit lp cc ng d

phng LSP trong trng hp c s h hng tuyn.. Tuy nhin, nu trong trng

hp thit b ng xung t chi nhn ngh v a ra ngh ring ca nt v

tham s kin to LSP th thit b ng xung phi nh li cu hnh vi nhn mi.

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2.3.2 LSP hai hng

Bo v mng chng li nhng h hng ca mng, chng hn nh t si cpquang trong mng quang s cung cp chc nng tm si quang thay th trong cc

cu cu trc mng c th . Cng tng t nh vy, cc LSP c thit lp trong

mng quang cng cn phi c bo v. Vn ny c gii quyt bng cch thc

hin cc LSP hai chiu n hng, mi LSP mt hng s l s phng cho LSP

hng kia. LSP hai hng s thc hin k thut lu lng v c ch phc hi ging

nhau trn mi hng. GMPLS thc hin chc nng kin to cc LSP hai hng

thng qua cc mt tp bn tin giao thc bo hiu (v d cc bn tin RSVP/PATH vRESV).

2.3.3 Tnh m rng

Chc nng chuyn tip LSP cn k (Forwarding K cnLSP (FALSP)

Chc nng FA-LSP ny c thc hin trn c s cc LSP ca mng GMPLS

truyn ti cc LSP khc. Mt FA-LSP c thc hin gia hai nt mng GMPLS

c xem nh l mt ng kt ni o c nhng c tnh k thut lu lng ring

bit v c thng bo cho chc nng OSPF/IS-IS nh mt ng thng ging nh

bt k mt ng thng vt l no. Mt FA-LSP c th c lu vo trong d liu

nh tuyn nh tuyn ng. ng thi, mt FA-LSP c th c nh s hoc

khng nh s ty thuc vo vic xem FA-LSP l mt ng thng bnh thng

hay khng.

Hnh trn m t c ch hot ng ca mt TDM LSP (LSPtdm), n c xemnh l mt ng thng kt ni gia hai thit b LSR nh tuyn gi trong mng

PSC thay v l mt ng thng kt ni vt l nh trong mng TDM.

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Hnh 2.1: C ch chuyn tip k cn

2.3.4 Cu hnh LSP

Cu trc mng (bao gm cc lp truy nhp, lp li v lp mng trc). Githit rng khi nhu cu kt ni trn mng tng ln, ngha l xut hin nhng kt ni

dng lu lng t u cui ti u cui ca cc doanh nghip t lp mng truy

nhp yu cu. Nu nh cc nt mng khng c c ch nh bng thng mt cch

mm do, ngha l ch c cc bng thng c nh kt ni gn vi cc ng thng

vt l th vn l rt kh gii quyt. Trong trng hp nh vy, mt lung bng

thng kt ni vt l STM-64 gia hai chuyn mch OXC ca mng ng trc cng

khng th truyn ti mt dng lu lng yu cu vi tc 100 Mbps t lp truy

nhp.

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Hnh 2.2: Cu hnh mng

2.3.5 C ch b ng

Trong tng lai c th s pht trin ca mng quang s l rt dy c. Mt mng

cp quang c cn phi qun l c th ln ti hong chc ti hng trm si quang

trn cng mt tuyn, mi mt si quang li c th truyn ti hng trm ti hng

ngn bc sng quang, vic qun l ng, qun l tuyn s tr ln rt phc tp

nu nh khng c mt cch thc hp l.GMPLS a ra mt phng thc qun l

ng v tuyn trong mng quang tng i hp l l phng thc b ng.

Phng thc b ng cho php ghp mt vi ng vo lm mt v thng bo

v ng cho cc giao thc nh tuyn, chng hn nh OSPF, hoc IS-IS. Thng

tin truyn ti theo phng thc ny c th l mang tnh cht rt gn v khng y

nhng u im l dung lng x l s gim i rt nhiu nu nh s dng

phng php lu tr c s d liu nh tuyn.

K thut b ng ch cn mt ng iu khin, iu cho php gim s

lng bn tin bo hiu iu khin cn phi x l.

GMPLS c th cho php b ng mt cch mm do theo phng thc im

im (PTP) thc hin cho cc LSP v thng bo thng tin b ng ny cho cc

giao thc OSPF (chuyn tip cn k).

Tuy vy, phng thc b ng ny cng bc l mt s hn ch nh:

- Ton b cc ng trong cng mt b phi bt u v kt thc trong cng mt

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cp LSR.

- Ton b cc ng trong cng mt b phi c cng chung mt loi (v d nh

PTP hoc qung b).

- Ton b cc ng trong cng mt b phi c cng mt dng cho c ch chuyn

mch - PSC, TDMC, LSC, hoc FSC.

2.4 tin cy

tin cy (Reliability)

Hnh 2.3: Qu trnh thc hin qun l h hng trong mng GMPLS

Chc nng thc hin ca cc giao thc GMPLS cho php qun l v iu khin

cc h hng trn mng mt cch t ng. Khi xy ra h hng ti mt phn mng

no thi n s c pht hin, nh v v cch ly vi cc phn mnh mng khc.

y l mt im quan trng khi thc hin cc LSP t u cui ti u cui bng

phng thc ng hm qua cc LSP c cu hnh cao hn. Cc bc thc hin cnthit qun l mt h hng (xc nh, nh v, cch ly v phc hi c th hin

trong).

GMPLS thc hin c ch bo v chng li cc h hng trn knh kt ni (hoc

ng thng) gia hai nt mng cn k (bo v on) hoc bo v t u cui ti

u cui (bo v tuyn). cc chc nng m rng nh tuyn OSPF v IS-IS trong

mng GMPLS cung cp cc thng tin nh tuyn ngay c khi tuyn ang trong qu

trnh thit lp. Khi tuyn truyn ti lu lng c thit lp chc nng iu khin

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bo hiu s c thc hin kin to cc tuyn d phng theo hng ngc li

bng cc giao thc RSVPTE hoc CRLDP. Phng thc bo v tuyn c th l

dng 1+1 hoc M:N. Hnh 3.7 m t cc c cu thc hin chc nng bo v c h

tr bi mng GMPLS. Trong c cu bo v t u cui ti u cui cc tuyn scp v tuyn th cp c tnh ton v thc hin kin to sao cho l hai tuyn

ring r v vt l hoc l nhm cc knh kt ni khng c chung him ha.

PSC-LSP1

LSC-LSP1

Mang IDM-LSP1

Cp pht ng xen kd phng cho LSC -LSP1

(Bo v ng)Cc node LSC

Node 1

Cc nodePSC

Cc nodeTDM Knh hot

ng

IDM-LSP1

mang PSC-LSR

Bo v tuyn

Khi phc ng

Khi phc ngdn LSP

u cui -u cui

Knh bo v 1 Cc node TDM

Cc nodePSC

Hnh 2.4: C ch phc hi h tr bi mng GMPLS

Chc nng phc hi ng c thc hin trong mng GMPLS c thc hin

theo c ch phc hi ng. C ch ny i hi c cc c cu ci t ti nguyn

ng trn cc tuyn u ni. C hai phng php phc hi p dng trong mng

GMPLS, l phc hi knh kt ni v phc hi on kt ni. Phc hi knh kt

ni l tm tuyn thay th ti mt nt mng trung gian. Phc on kt ni l phc hi

tuyn cho mt LSP c th no c thc hin bt u t nt mng ngun tm

tuyn thay th xung quanh phm vi mng c s h hng.

2.5 Mt s vn tn ti trong mng GMPLS

GMPLS thc cht l b cc giao thc c m rng thc hin mt s chc

nng mi ca mng MPLS. Trong , mt s phn thc hin cn phi c chun

ha trong tng lai gn. Mt s vn trong mng GMPLS c cp di y

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cn c gii quyt.

2.5.1 Bo mt

Cc c cu nh tuyn truyn thng trong mng IP cho php kim tra ton bthng tin phn mo u gi tin xc nh nt chuyn tip gi tin . Tuy rng

cch thc hin nh vy tn nhiu thi gian x l nhng c u im l to iu kin

thun li thit lp cc Firewall cng nh m bo rng a ch ch v ngun ca

gi tin l duy nht trong phm vi ton cu. Trong mng GMPLS nhn c s dng

gia tng tc chuyn giao gi tin nhng ngha s dng gi tr nhn ch mang

tnh ni b trong phm vi mng GMPLS c th. Do vy, nhn s khng th s dng

cho iu khin truy nhp vi yu cu bo mt. gii quyt vn bo mt trongmng GMPLS c th p dng c ch bo mt ngay trong qu trnh thit lp kt ni,

ging nh thc hin trong mng X.25 hoc ATM.

S thnh cng ca mng GMPLS ph thuc vo kh nng phi hp hot ng

vi c s h tng mng hin c nh l ATM hoc Frame Relay. Kh nng kt hp

gia GMPLS vi mng ATM v Frame Relay chnh l s cho php h iu khin

bo hiu ca chng c th trao i thng tin vi nhau nh hai mng ging nhau vcng ngh thng qua mng a loi hnh.

Thc thi cc chc nng phi hp gia hai mng s phi i mt vi mt s vn

sau: - Phi hp iu khin hai mt phng iu khin vi cc giao thc bo hiu iu

khin khc nhau l mt cng vic phc tp (chng hn nh vn phi hp nh

tuyn PNNI trong mng ATM v OSPFTE trong mng GMPLS.

- Duy tr cht lng dch v trong mng a loi hnh cng l mt cng vic phc

tp.

- Chuyn mch GMPLS c th h tr cc loi hnh chuyn mch nh l chuyn

mch gi, chuyn mch TDM, chuyn mch bc sng / si iu ny ny sinh

mt vic l la chn t hp cc loi hnh d liu mt cch ph hp chuyn

i gia mng GMPLS v cc mng khc.

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2.5.2 H thng qun l mng

Mng GMPLS cn phi thc thi vic qun l cc LSP c s tng t hng ngn

n hng triu hot ng trong mng theo cc kha cnh lin quan nh tnh trnghot ng, nh tuyn, k thut lu lng v.v.. iu c ngha l h thng qun l

mng GMPLS l phc tp hn nhiu so vi mng khc, chng hn nh mng

Internet.

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CHNG III NH TUYN TRONG MNG GMPLS

Chc nng nh tuyn trong mng GMPLS c m rng t cc chc nng ca

MPLS, cc giao thc nh tuyn chnh c s dng l OSPF-TE, IS-IS-TE. Trong

bo co ny em ch gii thiu n giao thc nh tuyn OSPF-TE l giao thc t

ng xc nh cu hnh t-p mng, thng bo ti nguyn kh dng (v d nh bng

thng hoc loi hnh bo v...). Cc im ch yu ca cc giao thc ny l: thng

bo v loi hnh bo v ng (1+1, 1:1, khng bo v hoc lu lng ph), thc

hin tm ng (gia cc nt mng k cn) nng cao kh nng xc nh tuyn

thng m khng cn phi thc hin cc giao thc nh tuyn trn c s a ch IP.

Giao thc OSPF ng dng trong mng vin thng nh nu ln phn trc.

Phn ny ta ch xem xt giao thc OSPF-TE c m rng ng dng trong mng

GMPLS.

3.1 nh tuyn ng ngn nht

Thut ton ng ngn nht nh SPF v CSPF c s dng rng ri trong k

thut iu khin lu lng trc tuyn,cc kt ni cn c thit lp mt thi

im, ging nh kt ni yu cu n lin tip. Chng ta a ra khi nim gn ging

gi l nh tuyn da trn thit k (DBR), nh vic tnh ton ng ti u ngoi

tuyn (offline) c s dng ch dn vic ci t ng trc tuyn (online). Tnh

ton ng ngoi tuyn trong mng GMPLS khng c kh khn khi mng li quang

hoc mng ni th ch c khong t mt vi n 100 nt so vi 100 n 1000 nt

trong mng d liu thun tu. DBR c nhng u im nh thng tin yu cu davo nhu cu ca khch hng, tham chiu lu lng v php o t trc, xy

dng gn ng mt b o lu lng yu cu cho vic ti u ho ng truyn.

Chng ta s thc hin vic so snh, c lng trong mng GMPLS khng trong

sut di cc kt ni tnh v ng vi cc kiu m bo khc nhau. Kt qu cho

thy rng DBR tt hn SPF v CSPF di iu kin hot ng vi phm vi rng,

nhng li khng xc nh c ng sai trong vic tnh ton b o lu lng yu

cu. Chng ta xy dng s nh tuyn vi qun l ti nguyn v php o trc

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tuyn. Kt qu m phng ch ra rng qun l ti nguyn cung cp mt cch c hiu

qu lm gim bt nhng thiu st trong CSPF, v php o trc tuyn cung cp mt

cch c hiu qu ci thin s hot ng ca DBR khi thng tin lu lng yu cu

c s dng trong vic thit k ng DBR l khc nhau t lu lng yu cuthc t

H thng k thut iu khin lu lng (TE) trong mng MPLS v GMPLS da

trn cc phng php ging nhau, vi im khc nhau chnh l yu cu lu lng

hi t v sc cha ca ng lin kt v cc dch v rng buc. H thng k thut

iu khin lu lng trong mng kt ni c hng thng c phn bit nh l h

thng iu khin lu lng trc tuyn (online) hoc h thng iu khin lu lng

ngoi tuyn (offline). Vi h thng iu khin lu lng trc tuyn cc yu cu kt

ni c tha nhn l n ti mt thi im. i vi mi yu cu kt ni, mt h

thng iu khin lu lng trc tuyn tnh ton mi ng c lp khng cn bit

v cc yu cu n sau. Sau ng c xc nh v kt ni thng xuyn ci

t bo hiu. Tng thi gian t khi mt yu cu kt ni n, n khi n c thit

lp mt t 10 n 100 ms. V th vic xc nh ng trong h thng iu khin lu

lng trc tuyn phi tng i nhanh (tnh bng ms). Vi mt h thng iu khinlu lng ngoi tuyn ton b yu cu kt ni phi chc chn bit chnh xc mt

ng tr li u tin trc khi tnh ton. S dng thng tin cu hnh, sc cha ca

ng lin kt v b o lu lng yu cu, mt kiu server trung tm thc hin ti

u ho ton b xc nh ng cho mi yu cu kt ni. Vic thit k ng

ng hon thnh mt ln, h thng qun l mng s ci t kiu kt ni. Mt h

thng ngoi tuyn vi vic ti u ho ton b c th t c ci thin trong vic s

dng ti nguyn qua mt h thng trc tuyn. Tuy nhin tng thi gian cn vi mt

h thng ngoi tuyn n nhiu pht hoc hng gi.

Khng ging vi vic qun l mng trong mng truyn ti truyn thng, mng

GMPLS-based s dng nh tuyn ng v bo hiu cho php cc kt ni thit lp

theo yu cu trong vic tr li yu cu ca khch. V th k thut iu khin lu

lng trc tuyn trong mng GMPLS-based c xem xt nhiu nh kiu hot

ng ph hp hn, khi cc dch v mi yu cu cung cp nhanh th c th sn sngcung cp. K thut iu khin lu lng trc tuyn cng c quan tm nhiu trong

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mng GMPLS, khi k thut thit k ng c tch hp trong mi nt cho php t

ng thit lp ng x l v cc bc cu hnh nh nht.

T nh tuyn ng ngn nht n nh tuyn da trn thit k

Trong phn trc, chng ta phn bit thut ton nh tuyn i vi k thut iu

khin lu lng. Phn bit ny th khng dng nghin cu k hn. Tuy nhin, n

c lc s dng trong cc php o ngoi tuyn v trc tuyn, ti u ho ni

b v ton cu, k hoch qun l ti nguyn v yu cu bo hiu. mc cao nht

thut ton c th phn bit theo vic ti u ho ti nguyn s dng c c hay

khng. Nhm nh tuyn da trn thit k th th hin bng cch s dng c lng

b o lu lng yu cu v ti u ho ton b ng. Nhm nh tuyn path-shortest bao gm tnh ton ng chc chn ngn nht, vi hoc khng cn qun l

ti nguyn, i vi mt cp ngun-ch mt thi im. Thut ton nh tuyn

trong nhm ng ngn nht bao gm thut ton SPF v CSPF chun. Trong nhm

ny, chng ta cng m rng vic qun l ngun, gi l CSPF-TR.

Thut ton nh tuyn trong nhm nh tuyn da trn thit k c th pht trin

hn na da vo vic s dng cc php o trc tuyn. Trong DBR cc ng tnh

ton li ti u da vo kin thc gn ng ca b o yu cu c s dng ci

t ton b ng ngun ch trc tuyn. Trong k hoch , gi l tng ng

DBR, php o trc tuyn c s dng cho vic chn ng v iu khin u vo.

Hnh di y gii thiu cc thit b chnh cho DBR framework. Thit b ti u ho

ng truyn ly thng tin t cng vo, nh cu hnh mng, sc cha ca lin kt,

c lng lu lng yu cu, v thng tin c lin quan khc nh cng bc. Da

vo thng tin cng vo ny, k thut DBR tnh ton ti u ton b ng c th

ngoi tuyn v lu kt qu trong mt database s dng v sau. Thit b iu

khin u vo lm ti u ho s dng, kt qu lu trong mt database. Trong DBR

c s, iu khin u vo ch p dng trn ng DBR. Trong tng ng DBR,

iu khin u vo ng dng trong DBR, nh ng k tip (v d: CSPF).

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Yu cu kt ni

Ci t trc tuyn

Ci t kt ni

D l iu c bn DBR

S offline

Thu thp dliu v yu cu

phn tch

Thng tin trng thichn ng lin kt

nh gi nhu culu lng

Qun l iu khin cs thit k cc ng

dn theo bn phn

ng dn tiu vi DBR

Hnh 3.1: Cc thit b cho DBR framework c s

Nghin cu s hot ng

Chng ta bit rng mt mng truyn ti quang h tr nh tuyn ng (OSPF-TE)

phn phi thng tin trng thi lin kt v mt giao thc bo hiu (RSVP-TE)

thit lp kt ni theo yu cu.

Mc tiu chnh l so snh DBR vi cc phng php thit k ng khc di

cc iu kin khc nhau. V d, Chng ta bit hai phng php thit k ng

trc tuyn, c pht trin rng ri l SPF v CSPF. SPF chn mt ng c gi

tr nh nht. Vic thc hin ca CSPF cng ging nh trong SPF, tr ra cc lin kt

c rng bng thng khng ph hp hoc rng buc khc trc tin s c gim

bt. Sau SPF s chy trn mng xc nh .

Chng ta xem xt hai kiu kt ni: Tnh v ng. Trong kiu tnh, yu cu kt ni

n ln lt (one-by-one). Mi yu cu c th nhn dng nt li vo v nt li ra,

v c nhim v thit lpkt ni gia nt li vo v nt li ra. Nu kt ni nh

tuyn c thnh cng, n s tn ti sut qu trnh hot ng. Nu yu cu kt ni

b tc nghn, th qu trnh tc nghn b mt sut qu trnh hot ng. Lu kiu

tnh ging nh kiu mch o c nh (PVC) trong mng ATM.

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Trong kiu ng, yu cu kt ni n c mc nh, thi gian ca kt ni l gii

hn. Mt yu cu kt ni b tc nghn th s mt sut trong qu trnh hot ng.

Kiu ng ny c th m rng hn khi khch hng ca mng quang l mng s

dng bng thng theo yu cu, m c th s dng cho k thut lu lng trongmng khch. Trong phn ny, vic thit lp kt ni v ng xung c khi

xng bi nt khch theo yu cu thng qua giao din quang gia ngi s dng v

mng (O-UNI). Ch l kiu ng ging nh kiu mng chuyn mch o (SVC)

trong mng ATM.

Mng quang c th hot ng di cc s m bo khc nhau ph thuc vo cc

yu cu dch v. C ba kiu ng m bo i vi tt c k hoch nh tuyn:

- Khng m bo

- Mt hot ng v mt d phng(1+1 hoc 1:1). m bo ng ch nh

- m bo ng dng chung (1:1)

3.2 K thut nh tuyn li nhanh

Cng ngh MPLS s dng k thut kt ni c hng nn n gp phi hn ch nh

thi gian tr li chm t thit b mng, v th thi gian cn thit lp mt LSP mi mang lu lng o.

Li lin kt thng do cc dch v chia s trong mng my tnh.. Li trong cc

lin kt c kh nng cha cao hoc gia cc b nh tuyn ng trc, c th nh

hng nghim trng n lung a truy nhp, cc dch v ng dng thi gian thc

tuyt i v cc giao thc. lm gim bt vn ny ngi ta a ra phng

php nh tuyn li nhanh. K thut nh tuyn li nhanh da trn vng cnh trc m mt mt LSP d phng c tnh ton, thng bo v ci t t

trc, khi mt li lin kt c pht hin. LSP d phng kt hp vi mc tiu sa

cha bn trong lm nh nht s mt gi trong thi gian khi phc. Hin nay

chng ta tng cng k thut nh tuyn li nhanh cho mng MPLS-based m lu

lng nh tuyn li thng qua mt LSP d phng khi mt lin kt/nt ca LSP bo

v b li. Mc ch l cung cp cht lng dch v cho lu lng mang bi LSP bo

v, thm ch trong trng hp li trong qu trnh khi phc, cho n khi n tnh

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ton xong. LSP khng bo v c th nh tuyn li nhng khng c bo m (n lc

ht sc). Thc hin xut ca chng ta tt hn so vi thc hin xut trong c

tr gi v mt th t gi. Chng ta cung cp mt thut ton ngn gn v n gin

trong LSRs trung gian m hot ng theo mt kiu phn b no , gii thiu chcnng truyn thng lm gim vic sp sp li th t gi v lm gim tr truyn

thng khng cn thit.

K thut a ra c th s dng cho vic cung cp cht lng dch v (QOS). Bi

v thut ton c kh nng din t tiu chun khc hn l pht hin li lin kt cho s

hot ng ca n. Hn na mt LSP nh sn pht hin tc nghn hoc trng

thi dn n tho thun mc dch v (SLA) hoc tho thun Cht lng dch v

(QoS) b vi phm, th LSP bo v bt u nh tuyn li nhanh. m rng k

thut ca chng ta n vn tc nghn th phi m bo rng LSRs cn phi c

kin thc v vn tc nghn. Ch trong trng hp li lin kt, lung c th i

trch hng n mt LSP khc th tnh hung tc nghn c pht hin. Thut

ton a ra c nh gi thng qua m phng v kt qu cho thy s ci thin

trong tr truyn gi trung bnh. xut a ra gim bt vic sp sp li th t gi,

ci thin hiu sut u cui v thi gian khi phc li ngn hn so vi xut caHaskin.

Chng ta tha nhn trong xut ca chng ta tt c cc LSPs bo v trn mt

lin kt ging nh l mt LSP thay i li v theo hon ton kin trc MPLS.

M rng ca MPLS trong mng quang l GMPLS, cho bi kh nng mang c bit

ca LSP bo v trn lambda (DWDM).

3.3 D phng trong GMPLSng d phng c th c chn sn sng truyn lu lng gia LSP ngun

v ch khi m bt k mt lin kt/nt no b li nh tuyn c s. Mt vn quan

trng l chn c s v chn tuyn d phng trong bng m c s yu cu ca LSP

ln nht c th c th cung cp trong tng lai. V th nn x l vic chon tuyn,

ngn nga cc lin kt vt l khi m mng c s cp ngun ch ln.

C s ca ng d phng khng m nhim nhng ri ro ging nhau ca li,

ni cch khc li ging nhau c th gy ra bi li ng dn. Nu mt ti nguyn

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c nm gi bi mt ng bo v m ti nguyn c th chia s, ging nh

l c th nm gi bi mt ng bo v khc, cho n con s ln nht cho php

trn ti nguyn . a ng bo v chia s ti nguyn chung khng hot ng

ng thi. t c iu ny thut ton nh tuyn phi khng cho php ngbo v chia s ti nguyn nu ng c s c li chung. Bo v chia s thng

c s dng mng ln hn bo v ch dn. Tuy nhin, ch ng vi yu cu bo

v nghim ngt th cn c bo v lin tc. Nhng ng khc c th bo v bn

di bo v chia s m c th khi ti nguyn mng cn tha.

Chi ph ti nguyn trong ng d phng

Chi ph ti nguyn (RC) trong phng php m bo c nh gi ph thucvo vic s dng phng php phc hi. V d, chng ta a ra vic s dng

rng bng thng c cp trn mi lin kt. Chi ph ti nguyn c tnh ton trn

mi lin kt bi vic tnh ton s lin kt trn ng v rng bng thng c

cp trn mi lin kt. Vic cp ti nguyn c tha nhn l rng bng thng

trong khi cha truyn l: Rc = NL . RB

Vi RB l rng bng thng d tr, NL l s cc lin kt.

Cng thc trn tng ng dng m t phng php ng d phng khc nhau.

Chi ph ti nguyn cho phng php ton cu (RCG) ph thuc vo s cc lin kt

trong ng d phng (NLs). Chi ph ti nguyn cho phng php khi phc d tr

(RCR) l tng ca RCG vi yu cu ti nguyn i vi ng d tr (NLR.RB).

Chi ph ti nguyn cho phng php khi phc ni (RCL) ph thuc vo rng

bng thng d tr v s cc lin kt (NLL). Trong trng hp d phng ni, c

lu hn mt d phng ni c th c to ra m bo mt vi lin kt trongng hot ng. RC i vi phng php khc nhau c cho bi:

RCG = NLG.RB

RCR = RCG + NLR.RB

RCL = NLL.RB

Vi RCG, RCR, RCL l chi ph ti nguyn (tng ng cc phng php ton cu,

d tr, nh sn ni)

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NLG, NLR, NLL l s cc lin kt (tng ng cc phng php ton cu, d tr,

nh sn ni).

3. 4 nh tuyn khi phc m bo cht lng

Cc k thut khc nhau la chn ng ph hp ph thuc vo cc yu

cu m bo cht lng dch v (QoS). Cc thut ton nh tuyn s dng tm

ng i kh thi nht, Nhng thut ton c phn chia theo loi thng tin nh

tuyn v c s dng tnh ton ng chn ng. Vn quan trng th nht

trong thut ton nh tuyn phn lp l nh tuyn tnh hoc ng. Thut ton tnh

ch s dng vi thng tin mng tnh, cn thut ton ng s dng vi thng tin ti

lin kt c cp nht mt cch nh k. Vn th hai, thut ton nh tuyn cth nh tuyn trc tuyn (theo yu cu) hoc tnh ton ngoi tuyn (tnh ton t

trc). Vic tnh ton ng ng truyn vi thut ton nh tuyn trc tuyn din

ra lin tc, trong khi , thut ton nh tuyn ngoi tuyn khng theo vic tnh ton

chn mt ng mi v chng c tnh ton t trc.

3.4.1 Nguyn l v hot ng u tin

Mc ch chnh ca thut ton ny l tm ng truyn ti u nht (ng mbo Qos, rng bng thng) m t c hiu qu ti nguyn s dng. u tin

la chn ng c gi tr nh nht trong theo th t gim bt vic chi ph ti

nguyn. Th hai, cn bng ti trn mng (v d: ng c ti nh nht c

chn). Vic ti u ho s dng mng ny lm gim chi ph ti nguyn v cn bng

ti trn mng, vn ny khng d dng nu ch s dng mt thut ton, do hai

mc tiu thng khng ph hp vi nhau. Mt ng vi gi tr nh nht khng

tt yu khng c chi ph ti nguyn tt nht. Do , vic pht trin thut ton nh

tuyn m bo cht lng l ph hp. Mt cch ph hp pht trin thut ton

nh tuyn m bo cht lng, gi ly mc tiu cn bng ti v kh nng tnh ton

ti nguyn, l ng dng tiu chun nh tuyn mi hoc trn mt vi tiu chun

m bo cht lng. Nhng tiu chun m bo cht lng c th l: s bc

nhy nh nht, rng bng thng cn d ln nht, gi tr ng nh nht da vo

vic s dng lin kt.

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Mt phng php nh tuyn thng thng l s dng thut ton bc nhy nh

nht (min-hop algorithm MHA). Thut ton ny ch chn ng nh nht vi lin

kt thp nht gin nh tiu chun nh tuyn n. Thut ton ng ngn nht rng

nht (WSP) da trn thut ton Bellman-Ford cng c a ra. Hai tiu chunc trn l: th nht, chn ng vi s bc nhy nh nht gia tt c cc ng

ti u, th hai nu c hn mt ng chn th chn mt ng vi rng bng

thng d tr ln nht (MRB). MRB ca mt ng l nh nht gia trong s tt c

cc lin kt trn ng c bng thng d tr. Mt phng php nh tuyn khc

c a ra l ngc vi thut ton WSP. Trong trng hp ny, u tin u tin

chn ng vi rngbng thng nh nht v nu c hn mt ng ti u th

ng vi s bc nhy nh nht c chn. Thut ton ny gi l ng rng nht

ngn nht (SWP) WSP u tin cao nht cho vic s dng ti nguyn trong khi SWP

dng cho vic cn bng ti trn mng. xut khc nh ngha chc nng ca gi

tr (cost) v ng dng tnh ton ng ngn nht da trn gi tr .

Tuy nhin, cc thut ton hin ti c mt vi hn ch khi chn mt ng vi s

bc ln hn (trong trng hp ca WSP) hoc ng vi mt tiu chun cp cho

rng bng thng, c hai trng hp ny c th tr thnh im hn ch. lmgim iu ny, xut khc c a ra l dng bin php cng p cc hot ng

ca thut ton lm gim cc hn ch ca n. Trong thut ton ng thay th

ng (DAP), gii hn bc nhy c s dng ngn nga ng c chn ln

hn mt ngng l s bc nhy c tnh ton bi MHA. y l c s ca mt

thut ton WSP vi gii hn s bc nhy.

3.4.2 Thut ton nh tuyn trc tuyn m bo cht lng trong MPLSMPLS c kh nng thc hin d dng php o m bo cht lng la chn

mt ng mi. (LSPs). Trong phn ny ta xem xt mt vi xut nh tuyn trc

tuyn m bo cht lng dch v ca MPLS, nhng u im v nhc im.

nh tuyn ng trong vic m bo bng thng ng ngang vi vic khi phc

d liu.

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y l mt xut u tin c a ra xem xt MPLS trong vic thit kt

thut ton nh tuyn. H pht trin thut ton nh tuyn trc tuyn m bo

rng bng thng LSPs nh tuyn d phng v ng hot ng ging nh cc

yu cu n. Trong thut ton ny, nu rng bng thng thit lp c nghot ng v d phng m cha sn sng, th yu cu b loi b. Ch bo m cc

li lin kt/nt s c tnh ton ti. D phng a ng c thit lp v v th c

kh nng d phng s phi c chia ra.

Cc thut ton nh tuyn khc, da trn h thng cha sn sng tnh ton

ng, c a ra. Cc phng php v c bn tnh ton vn v chiu di

ca chng trnh theo s nguyn. Mt thut ton vi s kt hp thng tin s dng

rng bng thng lin kt (gi l nh tuyn ng vi thng tin mt phn) c

a ra nh l mt gii php tt trong vic tnh ton gi tr v hiu sut mng.

Mc ch chnh ca xut ny pht trin thut ton nh tuyn trc tuyn

s dng rng bng thng nh nht. Khng ging nh cc xut khc phng

php ny khng xem xt n vic ti u ho t l yu cu loi b, ging nh mc

ch ban u. Hn ch chnh ca xut ny l yu cu loi b s bc nhy hoc

yu cu d phng a ng.

3.4.3 Thut ton nh tuyn khi phc ng

Trong xut ny vic thit lp ng vng (d phng) cho mi lin kt hoc

nt ngang bi ng hot ng ban u. S dng khi phc ni (d phng ni) vi

chi ph ti nguyn chia s. So snh gia hai mng thng tin khc nhau v kt hp

vic s dng thng tin trn mi ng, cung cp thng tin cho vic chn ng

c hiu qu vi rng bng thng ni v ng d phng bo m. Thut ton

ny ch cho bit mt phn nh v rng bng thng ca mi lin kt, c s

dng cho cc ng hot ng v chc nng s dng ca ng d phng.

3.5 K thut lu lng trong trong GMPLS

Gii thiu

Mc ch ca TE (k thut lu lng) l tng hiu qu v tin cy vn hnh

mng khi ti u ho vic s dng ti nguyn mng v hiu nng lu lng. Trong

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vi nm gn y lng lu lng bi cc dch v da vo Internet ngy cng tr

nn r rng hn. Do , cc thit b trong tng lai phi c kh nng a dch v

h tr cc loi dch v khc nhau vi cc yu cu QoS khc nhau. Tnh khng n

nh v khng d on trc c ca lu lng Internet, a ra cc yu cu thchthc cho NGN: tnh mm do v kh nng phn ng li nhanh chng s thay i

lu lng. Phng php da vo cung cp ti nguyn vt qu c s dng trong

cc mng vin thng ngy nay khng phi l gii php mang li li nhun cho

NGN.

3.5.2 Vai tr ca MPLS

Kin trc MPLS cn c vo s ngn cch gia mt phng d liu v mt phngiu khin, ti s dng v m rng cc giao thc IP hin ti cho cc chc nng nh

tuyn, bo hiu, khi m li a vo mt m hnh hng kt ni trong bi cnh da

vo Internet. N da vo s ng cc gi IP thnh cc gi c gn nhn m c

gi vo min MPLS theo kt ni o c tn l tuyn chuyn mch nhn (LPS). Cc

phn t chnh ca mng MPLS l b nh tuyn chuyn mch nhn (LSRs)-thc

hin chuyn mch nhn, v cc b nh tuyn nh (E-LSRs)-hot ng ti u vo

v u ra ca min MPLS. Mi kt ni o, ngha l mi LPS, c th c thit lp

ti LSR u vo bi iu khin theo th t, trc khi gi cc gi. LSP ny c th b

p theo mt tuyn m quyn u tin c tnh nh vo chc nng nh tuyn hin.

c trng ch yu ca m hnh MPLS lin quan ti kh nng ti s dng ngun ti

nguyn mng trn mt tuyn ring bit bi cc giao thc bo hiu ph hp (v d:

RSVP-TE, CR-LDP). Do , LSP biu din mt kt ni o trong mng MPLS nh

cc mch o v cc tuyn o trong ATM.C th, mi LSP c th c thit lp, xo b, nh tuyn li nu cn, v c

iu chnh bi s bin i mt s thuc tnh ca n, gm c bng thng. Thc cht,

bng thng ca LSP c th iu chnh mt cch t ng, tng theo mong mun,

theo mt yu cu c bit ti LSR u vo duy tr tt c cc thuc tnh khc.

Hn na, k thut chim hu trc trong LSP cng c th c s dng h

tr cc lung d liu c u tin cao hn trnh tranh chp trong mng. c trngquan trng khc ca MPLS lin quan ti kh nng sp xp cc nhn a ra cc

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mc c th bc khc nhau thay v hai mc trong ATM. c trng ny h tr cc

dch v VPN, cho php m rng iu khin MPLS cho cc cng ngh khc.

3.5.3 nh tuyn trn c s rng buc: thnh phn chnh cho xy dng lu

lng

S kt hp ca chc nng nh tuyn hin, k thut dnh ring ti nguyn v

nh tuyn trn c s rng buc (CBR) trong mng MPLS biu din cc thnh phn

chnh thc hin chin lc xy dng lu lng hiu qu. C th, tiu chun c

s dng chn cc tuyn trong mng v nh tuyn li cc lung lu lng theo

cc tuyn khc, l quyt nh trong vic p dng cc chin lc TE. Chun ny cn

tnh nhiu tham s hn cu hnh mng n gin. Tm tt hot ng nh tuyn trnc s rng buc c minh ho trong hnh 3.14. Thc ra, khi tnh ton tuyn cho

ng dn c yu cu (LSP trong trng hp mng MPLS), CBR phi xem xt

c rng buc mng v ngi s dng. Vn trc quan tm ti trng thi lin kt,

kh dng ca ti nguyn ngoi cu hnh mng, trong khi vn sau lin quan ti

cc yu cu bng thng, cc nhm kinh doanh, quyn u tin,.... Khi tuyn hin

c tnh, th tc dnh ring ti nguyn c bt u bi cc giao thc bo hiu

nh RSVP. Theo cch ny, CBR tm tuyn di hn nhng nh hn cc tuyn b tc

nghn thay v cc tuyn ngn nht. Do lu lng mng c phn b u hn v

tc nghn c ngn cn.

Cc rng buc mng(trng thi lin kt, ti

nguyn d tr, cu hnhmng)

Rng buc ngu tin ngnnht(CSPF)

Cc rng b uc ngi sdng (nhm qu n l

rng bng thng yucu, u ti n)

nh tuyn hin

Ginh trc ti nguyn(v d: RS VP-TE, CR-

LDP)

Hnh 3.2: Nguyn l nh tuyn trn c s rng buc

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C hai phng php chnh c xem xt tnh ton tuyn l: trc tuyn (on-

line), ngoi tuyn (off-line). V c bn, phng php off-line lin quan ti tnh

tuyn c xc nh trc, thng c thc hin bi cng c ti u ho mng

ngoi, cn phng php on-line lin quan ti tnh ton tuyn theo yu cu, t ct ng bi cc giao thc bo hiu hoc bi cng c ngoi tuyn. Phng php off-

line thch hp t c tuyn ti u ton b trn c s ma trn lu lng (biu

din cc yu cu kt ni bit trc cho mi cp node mng). V mt logic, phng

php ny rt thch hp khi nhu cu lu lng l kh n nh: ngha l s thay i

lu lng khng lin quan ti yu cu thit k li tuyn cho cc lung d liu khc.

l trng hp lu lng thoi truyn thng m hon ton c th d on c

v kh n nh: v vy ma trn lu lng kh nht qun. Nhng lu lng Internet

khng d on c m cng khng n nh. V vy, phng php off-line khng

thch hp v hoc l n dn n lng ph ti nguyn mng (cc ng truyn dn

khng c lp y) hoc xy ra tc nghn do lu lng tng v ti nguyn c

cp pht khng . p ng li nhanh chng cc thay i lu lng Internet,

phng php on-line tho mn hn. C th, phng php nh tuyn on-line gm c

c lng tuyn theo yu cu, khi cn, ngha l, khi c mt yu cu hoc thay i

yu cu trc. Do , n thch hp thc hin qu trnh iu chnh LSP k tip.

Vn chnh trong cc trng hp ny l duy tr s n nh. Thc cht, tnh n

nh c th xut hin khi thi gian cn thit nh tuyn mt lung d liu mi l

bc ca thi gian u tin m yu cu c bt u. R rng, phng php on-line

cng khng ph hp thc hin qu trnh iu chnh tuyn. Tuy nhin, nh tuyn

on-line cn tiu th nhiu ti nguyn hn. Kt qu l, phng php lai l mt gii

php tt nht khai thc cc u im ca c hai phng php.

T ta thy CBR trong cc mng thc t l mt vn ct yu v phc tp.

y ta xut mt h thng xy dng lu lng thc t, s dng phng php nh

tuyn lai mi. C th hn, h thng TE vin dn th tc off-line t c tnh

ton cc tuyn ti u ton b, theo ma trn lu lng, cn vic dn th tc nh

tuyn on-line iu chnh t ng mt cch tun t cc yu cu lu lng thc t,

cho php p ng nhanh chng s thay i lu lng.

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