Ip Tren Quang

7/30/2019 Ip Tren Quang

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B gio dc v o to

Trng i hc bch khoa h ni--------------------------------------------

lun vn thc s khoa hc

cng ngh mng truyn dn th h miIP/WDM

ngnh: x l thng tin v truyn thng

M s:

tiu xun hng

Ngi hng dn khoa hc: PGS -TS. ng vn chuyt

h ni 2006


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Li cam oan

Em xin cam oan lun vn ny l cng trnh nghin cu ca chnh bn

thn. Cc nghin cu trong lun vn ny da trn nhng tng hp l thuyt

v hiu bit thc t ca em, khng sao chp.

Tc gi lun vn

Tiu Xun Hng


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- -I

Mc lc

Mc lc ..............................................................................................................................I

Thut ng vit tt ....................................................................................................IV

danh mc cc hnh v..........................................................................................VIII

m u ...............................................................................................................................1

Chng 1: gii thiu v mng truyn dn th h mi hin nay vxu hng pht trin .................................................................................................21.1 Gii thiu chung .......................................................................................... 2

1.2 Cu trc mng th th mi hin nay ........................................................... 2

1.3. Lp truyn dn v truy nhp hin nay ....................................................... 3

1.3.1 Phn truyn dn:................................................................................. 3

1.3.2. Phn truy nhp: ................................................................................. 4

1.4 Cc cng ngh s dng cho mng th h mi hin nay. ............................. 5

1.4.1. Cng ngh IP...................................................................................... 5

1.4.2. Cng ngh ATM ................................................................................. 7

1.4.3. Cng ngh IP / ATM .......................................................................... 8

1.4.4. MPLS................................................................................................ 10

1.4.5 Ghp knh phn chia theo bc sng WDM v DWDM...................11

1.5 Xu hng tch hp IP/quang trong mng NGN......................................... 12

Chng 2: Mng IP/WDM............................................................................................142.1 Gii thiu mng IP/WDM.......................................................................... 14

2.1.1 Gii thiu mng quang WDM ........................................................... 14

2.1.2 Mng IP/WDM.................................................................................. 16

2.2 Cc kin trc mng IP/WDM................................................................... 182.2.1 Cc kiu kin trc mng.................................................................... 18

2.2.1.1 Mng IP/ WDM im-im .................................................... 19

2.2.1.2 Mng IP/WDM c kh nng cu hnh li ................................ 19

2.2.1.3 Mng IP/WDM c kh nng chuyn mch............................... 20


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- -II

2.2.2 Cc m hnh lin kt mng IP/WDM................................................ 24

2.2.2.1 IP/ WDM c th cu hnh. ....................................................... 24

2.2.2.2 IP/WDM c kh nng chuyn mch ......................................... 28

2-3 Kt lun..................................................................................................... 32

Chng 3: iu khin mng trong mng IP /WDM.......................................343.1 a ch mng IP/WDM.............................................................................. 36

3.2 Nhn bit topo mng................................................................................. 39

3.3 nh tuyn IP/WDM.................................................................................. 41

3.3.1 Xy dng v duy tr c s thng tin nh tuyn OSPF ...................... 41

3.3.2 Tnh ton ng i v nhng rng buc chuyn mch WDM. ........ 43

3.3.3 Hot ng nh tuyn........................................................................ 46

3.4 Bo hiu trong mng IP/WDM.................................................................. 48

3.4.1 Khi nim RSVP................................................................................ 48

3.4.2 RSVP trong mng quang ................................................................... 51

3.4.3 Kin trc trin khai RSVP................................................................. 52

3.4.4 Bn tin RSVP trong mng quang....................................................... 53

3.4.5 C ch pht nhn lai cho mng quang (Hybrid Label) .................... 57

3.5 GMPLS (Generalized-Multiprotocol Label Switching)........................... 60

3.6 Phc hi IP/WDM..................................................................................... 62

3.6.1 Trng hp c d phng:.................................................................. 67

3.6.2 Trng hp phc hi:........................................................................ 69

3.7 iu khin mng lin min: ...................................................................... 71

3.7.1 kh dng v kh nng n ch ca mng IP/WDM................... 73

3.7.2 Trao i thng tin nh tuyn lin min: .......................................... 76

3.8. Kt lun v iu khin trong mng IP/WDM........................................... 81

Chng 4:K thut iu khin lu lng trong mng IP/WDM .........824.1 Phng php v m hnh........................................................................... 82


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- -III

4-2 iu khin lu lng mng IP/WDM theo m hnh chng ln................. 83

4-3 iu khin lu lng mng IP/WDM tch hp ........................................86

4.3.1 K thut iu khin l

u l

ngnh tuyn tch hp..........................87

4.3.2 Khi nim lin kt o ........................................................................ 88

4.3.3 Thut ton nh tuyn tch hp:........................................................ 89

Chng 5: pht trin mng truyn dn th h mi ti Vit Nam .925.1. Cc cng ngh ang c s dng cho mng truyn dn th h mi ti

Vit Nam.......................................................................................................... 92

5.1.1 Mng IP/ATM/SDH/WDM:............................................................... 92

5.1.2 Mng IP/POS (Packet over Sonet)/WDM :....................................... 93

5.1.3 Mng IP/WDM im-im:............................................................... 94

5.1.4 Trin khai mng NGN ca VNPT..................................................... 94

5.2 Kh nng ng dng l thuyt IP/WDM vo mng vin thng................... 95

5.3 xut ng dng mng IP/WDM cho mng th h mi ca VNPT trong

tng lai........................................................................................................... 99

5.4 Kt lun v trin khai mng truyn dn th h mi ............................... 100

Kt lun........................................................................................................................102

ti liu tham kho .................................................................................................103

Tm tt lun vn ....................................................................................................104


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- -IV

Thut ng vit tt

ADM

ADSLAPI

APS

ARP

AS

ATM

BASE

BEBER

BGMP

BGP

CDMA

CLI

DCC

DCN

DEMUX

Diffserv

DLC

DLCI

DM

DNS

DSL

DWDM

EBGP

EGP

Add/Drop Multiplexer

Asymmetrical Digital Subcriber LineApplication Programme Interface

Automatic Protection Switching

Address Resolution Protocol

Autonomous System

Asynchronous Transfer Mode

Baseband

Best EffortBit Error Rate

Border Gateway Multicast Protocol

Border Gateway Protocol

Code Division Multiple Access

Command Line Interface

Data Communication Chanel

Data Communication Network

Demultiplexer

Differentiated Service

Digital Loop Carrier

Datalink Connection Identifier

Domain Manager

Domain Name System

Digital Sucriber Line

Dense Wavelength Divison Mutiplexing

Exterior Border Gateway Protocol

Exterior Gateway Protocol


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- -V

EMS

FDM

FEC

FIFO

FTP

GbE

GMPLS

HDLC

HTML

HTTP

IAB

IBGP

ICMP

ID

IDMR

IDRP

IETF

IGMP

IGP

Intserv

IPng

IpSec

IPv4

ISDN

IS-IS

ISP

LAN

Element Management System

Frequency Divison Multiplexing

Forward Error Correction

Firt In Firt Out

File Tranfer Protocol

Gigabit Ethernet

Generalised Multiprotocol Label Switching

High Level Data Link Control

Hypertext Marup Langugage

Hypertext Tranfer Protocol

Internet Architecture Board

Interior Border Gateway Protocol

Interior Control Message Protocol

Identifier

Interdomain Multicast Routing

Interdomain Routing Protocol

Internet Engineering Management Protocol

Internet Group Management Protocol

Interior Gateway Protocol

Intergrated Service

IP Next Generation

IP Security

Internet Protocol Vesion 4

Intergrated Service Digital Network

Intermediate System to Intermediate System routing

protocol

InternetService Provider

Local Area Network


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- -VI

LBS

LDP

LIB

LMP

LSA

LSP

LSR

LSU

LTE

MAC

MIB

MPS

MPLS

NE

NGN

NMS

NNIOADM

OAM

OBS

OLS

OLSR

OPR

OSPFOXC

PON

POS

PPP

Label-Based Switching

Label Distribution Protocol

Label Information Base

Link Management Protocol

Link State Advertisement

Label Switched Path

Label Switched Router

Link State Update

Link Terminating Equipment

Media Access Control

Management Information Base

Multiprotocol Lambda Switching

Multiprotocol Label Switching

Network Element

Next Generation Network

Network Management System

Network to Network Interface

Optical Add/Drop Multiplexer

Operations and Maintenance

Optical Burst Switching

Optical Label Switching

Optical Label Switching Router

Optical Packet Router

Open Short Path FirstOptical Cross Connect

Passive Optical Network

Packet Over Sonet

Point to Point Protocol


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- -VII

QoS

RIP

RSpec

RSVP

RTP

SDH

SMTP

SNMP

SPF

SRLG

SS7

TE

TNM

TTL

UDP

UNI

VPN

WADM

WAMP

WAN

WDM

Quality of Service

Routing Information Protocol

Resource Specification

Resource Revervation Protocol

Real time Transport Protocol

Synchronous Digital Hierarchy

Simple Mail Tranfer Protocol

Simple Network Management Protocol

Short Path First

Shared Risk Link Group

Signaling System No 7

Traffic Engineering

Telecommunication Management Network

Time to Live

User Datagram Protocol

User Network Interface

Vitural Private Network

Wavelength Add/Drop Multiplexer

Wavelength Amplifier

Wide Area Network

Wavelength Division Multiplexing


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- -VIII

danh mc cc hnh v

Hnh 1-1: Xu hng tch hp cc lp giao thc IP/quang............................... 12

Hnh 2-1: Tin trnh pht trin mng WDM................................................... 16

Hnh 2-2: Truyn dn gi tin trn cc bc sng ........................................... 17

Hnh 2-3: Chuyn mch chm quang.............................................................. 21

Hnh 2-4: Chuyn mch gi quang ................................................................. 22

Hnh 2-5: IP qua mng chuyn mch WDM................................................... 23

Hnh 2-6: M hnh iu khin NMS chng ln............................................... 25

Hnh 2-7: M hnh iu khin gia tng........................................................... 26

Hnh 2-8: M hnh iu khin ngang hng ..................................................... 27

Hnh 2-9: Mng IP over OLSR........................................................................ 29

Hnh 2-10: Mng IP over OPR ....................................................................... 32

Hnh 3-1:iu khin lu lng v in khin mng IP/WDM........................ 34

Hnh 3-2: C ch flooding OSPF.................................................................... 42

Hnh 3-3: Vng lp nh tuyn........................................................................ 46

Hnh 3-4: RSVP cho mng quang WDM......................................................... 51

Hnh 3-5: Kin trc phn mm RSVP ............................................................. 52

Hnh 3-6: nh dng bn tin PATH i tng yu cu nhn ......................... 54

Hnh 3-7: nh dng bn tin PATH i tng yu cu nhn cho thit lp

ng i v cp pht bc sng ni b........................................................... 54

Hnh 3-8: nh dng bn tin RESV i tng nhn........................................ 57

Hnh 3-9: Phc hi mng IP/ WDM ............................................................... 63

Hnh 3-10: D phng lightpath v d phng lin kt ..................................... 68

Hnh 3-11: Phc hi mng v phc hi phn on con ................................. 70

Hnh 3-12: iu khin lin min IP/WDM ..................................................... 71

Hnh 4-1 M hnh mng chng ln ................................................................. 84


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- -IX

Hnh 4-2: V d v nh tuyn IP khng la chn link cung cp bi mng

WDM ............................................................................................................... 85

Hnh 4-3:M hnh ngang hng- iu khin l

u l

ng tch hp...................... 86

Hnh 4-4: Cu trc node nh tuyn tch hp ................................................ 87

Hnh 4-5: V d mng vi cc lin kt o........................................................ 89

Hnh 5-1: Mng IP/POS (Packet over Sonet)/WDM....................................... 93

Hnh 5.2 - M hnh mng NGN ca VNPT .................................................... 95

Hnh 5-3: xut ng dng mng IP/WDM cho mng th h mi ca VNPT

......................................................................................................................... 99

Hnh 5-4: Tin trnh pht trin mng IP/WDM............................................ 101

Hnh 5-5: Tin trnh pht trin mng IP/WDM ca Siemens ....................... 101


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- -1

m u

Hin nay mng vin thng ang tng bc thc hin chuyn dch t

mng vin thng hin c sang mng th h mi. Cc cng ngh truyn dn

th h mi c a vo s dng nh :

Mng SDH th h sau s dng WDM cho php phn pht d liu tc

cao v bng thng rng i vi mng Ethernet, cho php truyn lu lng

IP trc tip trn mng SDH.

Cng ngh IP lm nn cho th h sau trong cng ngh ghp knh

bc sng quang WDM chim lnh lp vt l; IP/MPLS lm nn cho lp 3,

truyn dn trn mng li da vo k thut gi cho tt c cc dch v vi cht

lng dch v QoS ty yu cu cho tng loi dch v. ATM hay IP/MPLS

hin ti c s dng lm nn cho truyn dn trn mng li m bo QoS.

Trong tng lai do s bng n lu lng IP dn n c s h tng mng

nn c ti u cho IP. Bn di lp IP, si quang s dng k thut WDM l

k thut truyn dn hu tuyn c nhiu ha hn nht, cung cp mt dung

lng mng khng l i hi tn ti trong s pht trin lin tc mng vin

thng. Chnh v l do trn hin nay cng ngh IP/WDM l xu hng cho mng

truyn dn th h mi, trong thi gian khng xa s c chun ho v a vo

s dng.

Da trn nhng hiu bit v cng ngh mng IP v cng ngh truyn

dn quang v cc nghin cu v cng ngh mng IP/WDM trong phm vi lun

vn em a ra nhng nghin cu l thuyt, kh nng ng dng ca Cng

ngh mng truyn dn th h mi IP/WDM bao gm: Cu trc mng, m

hnh lin kt, iu khin mng v iu khin lu lng trong mng IP/WDM.

Do hiu bit, thi gian nghin cu hn ch rt mong cc thy, c v

cc ng nghip gip , ng gp kin lun vn ca em c hon thin

hn.


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Lun vn cao hc -2 - Tiu Xun Hng_______________________________________________________________

Chng 1: gii thiu v mng truyn dn th h mihin nay v xu hng pht trin

1.1 Gii thiu chung

Chng ta nhn thy mng vin thng hin ti gm nhiu mng ring l

kt hp li vi nhau thnh mt mng hn tp, ch c xy dng cp quc

gia, nhm p ng c nhiu loi dch v khc nhau. Xt n mng Internet,

l mt mng n ln, c tnh cht ton cu, thng c cp theo mt

lot cc giao thc truyn dn hn l theo mt kin trc c trng. Internet hin

ti khng h tr QoS cng nh cc dch v c tnh thi gian thc (nh thoi

truyn thng). Do , vic xy dng mng th h mi (NGN) cn tun theo

cc ch tiu:

NGN phi c kh nng h tr c cho cc dch v ca mng Internet v

ca mng hin hnh.

Mt kin trc NGN kh thi phi h tr dch v qua nhiu nh cung cp

khc nhau. Mi nh cung cp mng hay dch v l mt thc th ring l vi

mc tiu kinh doanh v cung cp dch v khc nhau, v c th s dng nhng

k thut v giao thc khc nhau. Mt vi dch v c th ch do mt nh cung

cp dch v a ra, nhng tt c cc dch v u phi c truyn qua mng

mt cch thng sut t u cui n u cui.

Mng th h mi phi h tr tt c cc loi kt ni (hay cn gi l cuc

gi), thit lp ng truyn trong sut thi gian chuyn giao, c cho hu tuyn

cng nh v tuyn.

V vy, mng NGN s tin ha ln t mng truyn dn hin ti (pht

trin thm chuyn mch gi) v t mng Internet cng cng (h tr thm cht

lng dch v QoS).

1.2 Cu trc mng th th mi hin nay


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thc hin vic chuyn dch mt cch thun li t mng vin thng

hin c sang mng th h mi, vic chuyn dch phi phn ra lm ba mc

hai lp: kt ni v chuyn mch. Trc ht l chuyn dch lp truy nhp v

truyn dn. Hai lp ny bao gm lp vt l, lp 2 v lp 3, chn cng ngh IP

lm nn cho mng th h mi. Trong :

Cng ngh ghp knh bc sng quang DWDM s chim lnh lp vt

l IP/MPLS lm nn cho lp 3

Cu trc mng NGN bao gm cc lp chc nng sau:

Lp nt ni (Access + Transport/ Core)

Lp trung gian hay lp truyn thng (Media) Lp iu khin (Control) Lp qun l (Management)

Trong cc lp trn, lp iu khin hin nay ang rt phc tp vi nhiu

loi giao thc, kh nng tng thch gia cc thit b ca hng l vn ang

c cc nh khai thc quan tm.

Kin trc mng NGN s dng chuyn mch gi cho c thoi v d liu.

N phn chia cc khi vng chc ca tng i hin nay thnh cc lp mngring l, cc lp ny lin kt vi nhau qua cc giao din m tiu chun.

Trong phm vi lun vn ny chng ta i su nghin cu lp truyn dn

v truy nhp trong mng th h mi.

1.3. Lp truyn dn v truy nhp hin nay

1.3.1 Phn truyn dn:

Trong lp vt l truyn dn quang vi k thut ghp knh bc sng

quang DWDM c s dng.Trong lp 2 v lp 3 truyn dn trn mng li (Core Network) da vo

k thut gi cho tt c cc dch v vi cht lng dch v QoS ty yu cu cho

tng loi dch v. ATM hay IP/MPLS hin ti c s dng lm nn cho


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truyn dn trn mng li m bo QoS. Mng li c th thuc mng MAN

hay mng ng trc.

Thnh phn ca mng bao gm cc nt chuyn mch/ Router (IP/ATM

hay IP/MPLS), cc chuyn mch knh ca mng PSTN, cc khi chuyn mch

mng ng trc, k thut truyn ti chnh l IP hay IP/ATM.

Chc nng ca lp truyn ti trong cu trc mng NGN bao gm c

chc nng truyn dn v chc nng chuyn mch.

Lp truyn dn c kh nng h tr cc mc QoS khc nhau cho cng

mt dch v v cho cc dch v khc nhau. N c kh nng lu tr li cc s

kin xy ra trn mng (kch thc gi, tc gi, tr hon, t l mt gi v

Jitter cho php, i vi mng chuyn mch gi; bng thng, tr hon i

vi mng chuyn mch knh TDM). Lp ng dng s a ra cc yu cu v

nng lc truyn ti v n s thc hin cc yu cu .

1.3.2. Phn truy nhp:

Trong lp vt l gm cc loi cp hu tuyn nh cp ng s dng

xDSL hin ang s dng. Tuy nhin trong tng lai truyn dn quang

DWDM, PON (Passive Optical Network) s dn dn chim u th v th

trng xDSL, modem cp dn dn thu hp li. Truy nhp v tuyn bao gm

thng tin di ng - cng ngh GSM hoc CDMA, truy nhp v tuyn c nh,

v tinh.

Trong lp 2 v lp 3: Cng ngh IP s lm nn cho mng truy nhp.

Thnh phn ca mng truy nhp gm cc thit b truy nhp ng vai tr

giao din kt ni cc thit b u cui vo mng qua h thng mng ngoi

vi cp ng, cp quang hoc v tuyn. Cc thit b truy nhp tch hpIAD.Thu bao c th s dng mi k thut truy nhp (tng t, s, TDM,

ATM, IP,) truy nhp vo mng dch v NGN.

Chc nng lp truy nhp cung cp cc kt ni gia thu bao u cui

v mng ng trc ( thuc lp truyn dn) qua cng giao tip MGW thch


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hp. Mng NGN kt ni vi hu ht cc thit b u cui chun v khng

chun nh cc thit b truy xut a dch v, in thoi IP, my tnh PC, tng

i ni b PBX, in thoi POTS, in thoi s ISDN, di ng v tuyn, di

ng v tinh, v tuyn c nh, VoDSL, VoIP

1.4 Cc cng ngh s dng cho mng th h mi hin nay.

Ngy nay, yu cu ngy cng tng v s lng v cht lng dch v

thc y s pht trin nhanh chng ca th trng cng ngh in t - tin hc -

vin thng. S pht trin cng ngh v ang tip cn nhau, an xen ln

nhau nhm cho php mng li tha mn tt hn cc nhu cu ca khch hng

trong tng lai. Theo ITU, c hai xu hng t chc mng chnh:

- Hot ng kt ni nh hng (CO - Connection Oriented Operation).

- Hot ng khng kt ni (CL - Connectionless Operation).

Trong hot ng kt ni nh hng, cc cuc gi c thc hin vi

trnh t: gi s - xc lp kt ni - gi v nhn thng tin - kt thc. Trong kiu

kt ni ny, cng ngh ATM pht trin cho php y mnh cc dch v bng

rng v nng cao cht lng dch v. Hot ng khng kt ni da trn giao

thc IP nh vic truy cp Internet khng yu cu vic xc lp trc cc kt

ni, v vy cht lng dch v c th khng hon ton m bo nh trng hp

trn. Tuy nhin do tnh n gin, tin li vi chi ph thp, cc dch v thng

tin theo phng thc CL pht trin rt mnh m theo xu hng nng cao cht

lng dch v v tin ti cnh tranh vi cc dch v thng tin theo phng

thc CO. Tuy vy, hai phng thc pht trin ny dn tim cn v hi t dn

n s ra i cng ngh ATM/IP. S pht trin mnh m ca cc dch v v

cc cng ngh mi tc ng trc tip n s pht trin cu trc mng.

1.4.1. Cng ngh IP

S pht trin t bin ca IP, s tng trng theo cp s nhn ca thu

bao Internet l mt thc t khng cn ai c th ph nhn. Hin nay lng

dch v ln nht trn cc mng ng trc trn thc t u l t IP. Trong


17/115

Lun vn cao hc - 6 - Tiu Xun Hng_______________________________________________________________

cng tc tiu chun ha cc loi k thut, vic bo m tt hn cho IP tr

thnh trng im ca cng tc nghin cu.

IP l giao thc chuyn tip gi tin. Vic chuyn tip gi tin thc hin

theo c ch phi kt ni. IP nh ngha c cu nh s, c cu chuyn tin, c

cu nh tuyn v cc chc nng iu khin mc thp (ICMP). Gi tin IP

gm a ch ca bn nhn, a ch l s duy nht trong ton mng v mang y

thng tin cn cho vic chuyn gi ti ch.

C cu nh tuyn c nhim v tnh ton ng i ti cc nt trong

mng. Do vy, c cu nh tuyn phi c cp nht cc thng tin v topo

mng, thng tin v nguyn tc chuyn tin (nh trong BGP) v n phi c kh

nng hot ng trong mi trng mng gm nhiu nt. Kt qun tnh ton ca

c cu nh tuyn c lu trong cc bng chuyn tin (forwarding table) cha

thng tin v chng tip theo c th gi gi tin ti hng ch.

Da trn cc bn chuyn tin, c cu chuyn tin chuyn mch cc gi IP

hng ti ch. Phng thc chuyn tin truyn thng l theo tng chng mt.

cch ny, mi nt mng tnh ton mng chuyn tin mt cch c lp.

Phng thc ny, do vy, yu cu kt qu tnh ton ca phn nh tuyn ti tt

c cc nt phi nht qun vi nhau. S khng thng nht ca kt qu s dn

n vic chuyn gi tin sai hng, iu ny ng ngha vi vic mt gi tin.

Kiu chuyn tin theo tng chng hn ch kh nng ca mng. V d,

vi phng thc ny, nu cc gi tin chuyn ti cng mt a ch i qua cng

mt nt th chng s c truyn qua cng mt tuyn ti im ch. iu ny

khin cho mng khng th thc hin mt s chc nng khc nh nh tuyn

theo ch, theo dch v.

Tuy nhin, bn cnh , phng thc nh tuyn v chuyn tin ny

nng cao tin cy cng nh kh nng m rng ca mng. Giao thc nh

tuyn ng cho php mng phn ng li vi s c bng vic thay i tuyn khi

router bit c s thay i v topo mng thng qua vic cp nht thng tin v


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Lun vn cao hc - 7- Tiu Xun Hng_______________________________________________________________

trng thi kt ni. Vi cc phng thc nh CDIR (Classless Inter Domain

Routing), kch thc ca bn tin c duy tr mc chp nhn c, v do

vic tnh ton nh tuyn u do cc nt t thc hin, mng c th m rng

m khng cn bt c thay i no.

Tm li, IP l mt giao thc chuyn mch gi c tin cy v kh nng

m rng cao. Tuy nhin, vic iu khin lu lng rt kh thc hin do

phng thc nh tuyn theo tng chng. Mt khc, IP cng khng h tr cht

lng dch v.

1.4.2. Cng ngh ATM

Cng ngh ATM da trn c s ca phng php chuyn mch gi,

thng tin c nhm vo cc gi tin c chiu di c nh, ngn; trong v tr

ca gi khng ph thuc vo ng h ng b v da trn nhu cu bt k ca

knh cho trc. Cc chuyn mch ATM cho php hot ng vi nhiu tc

v dch v khc nhau. ATM c hai c im quan trng:

Th nht ATM s dng cc gi c kch thc nh v c nh gi l cc

t bo ATM, cc t bo nh vi tc truyn ln s lm cho tr truyn v

bin ng tr gim nh i vi cc dch v thi gian thc, cng s to iu

kin cho vic hp knh tc cao c d dng hn.

Th hai, ATM c kh nng nhm mt vi knh o thnh mt ng o

nhm gip cho vic nh tuyn c d dng.

ATM khc vi nh tuyn IP mt s im. N l cng ngh chuyn

mch hng kt ni. Kt ni t im u n im cui phi c thit lp

trc khi thng tin c gi i. ATM yu cu kt ni phi c thit lp bng

nhn cng hoc thit lp mt cch t ng thng qua bo hiu. Mt khc,ATM khng thc hin nh tuyn ti cc nt trung gian. Tuyn kt ni xuyn

sut c xc nh trc khi trao i d liu v c gi c nh trong sut

thi gian kt ni. Trong qu trnh thit lp kt ni, cc tng i ATM trung

gian cung cp cho kt ni mt nhn. Vic ny thc hin hai iu: dnh cho kt


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ni mt s ti nguyn v xy dng bng chuyn t bo ti mi tng i. Bng

chuyn t bo ny c tnh cc b v ch cha thng tin v cc kt ni ang

hot ng i qua tng i. iu ny khc vi thng tin v ton mng cha

trong bng chuyn tin ca router dng IP.

Qu trnh chuyn t bo qua tng i ATM cng tng t nh vic

chuyn gi tin qua Router. Tuy nhin, ATM c th chuyn mch nhanh hn v

nhn gn trn cell c kch thc c nh (nh hn ca IP), kch thc bng

chuyn tin nh hn nhiu so vi ca IP router, v vic ny c thc hn trn

cc thit b phn cng chuyn dng. Do vy, thng lng ca tng i ATM

thng ln hn thng lng ca IP Router truyn thng.

1.4.3. Cng ngh IP / ATM

Hin nay, trong xy dng mng IP c cc k thut nh IP / SDH/

SONET, IP/WDM v IP / Fiber. Cn k thut ATM do c cc tnh nng nh

tc cao, cht lng dch v (QoS), iu khin lu lng m cc mng

li dng b nh tuyn truyn thng cha c, nn c s dng rng ri

trn mng ng trc IP. MPLS chnh l s ci tin ca IP / ATM kinh in,

cho nn y chng ta cn nhn li mt cht v hin trng ca k thut IP /

ATM.

IP / ATM truyn thng l mt loi k thut kiu xp chng, n xp IP

(k thut lp 3) ln ATM (k thut lp 2); giao thc ca hai tng hon ton

c lp vi nhau; gia chng phi nh mt lot giao thc (nh NHRP,

ARP,) na mi m bo ni thng. iu hin nay trn thc t c

ng dng rng ri. Nhng trong tnh trng mng li c m rng nhanh

chng, cch xp chng cng gy ra nhiu vn cn xem xt li.Trc ht, vn ni bt nht l trong phng thc chng xp, phi

thit lp cc lin kt PVC ti N im nt, tc l cn thit lp mng lin kt.

Nh th c th s gy nn vn bnh phng N, rt phin phc, tc l khi

thit lp, bo dng, g b s lin kt gia cc im nt, s vic phi lm


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(nh s VC, lng tin iu khin) u c cp s nhn bnh phng ca N

im nt. Khi m mng li ngy cng rng ln, chi phi kiu s lm cho

mng li qu ti.

Th hai l, phng thc xp chng s phn ct c mng li IP / ATM

ra lm nhiu mng logic nh (LIS), cc LIS trn thc t u l trong mt

mng vt l. Gia cc LIS dng b nh tuyn trung gian lin kt, iu ny

s c nh hng n vic truyn nhm gi tin gia cc LIS khc nhau. Mt

khc, khi lu lng rt ln, nhng b nh tuyn ny s gy hin tng nghn

c chai i vi bng rng.

Hai im nu trn u lm cho IP / ATM ch c th dng thch hp cho

mng tng i nh, nh mng x nghip,, nhng khng th p ng c

nhu cu ca mng ng trc Internet trong tng lai.Trn thc t, hai k

thut ny ang tn ti vn yu km v kh nng m rng thm.

Th ba l, trong phng thc chng xp, IP / ATM vn khng c cch

no m bo QoS thc s.

Th t, vn khi thit k hai loi k thut IP v ATM u lm ring l,

khng xt g n k thut kia, iu ny lm cho s ni thng gia hai bn phi

da vo mt lot giao thc phc tp, cng vi cc b phc v x l cc giao

thc ny. Cch lm nh th c th gy nh hng khng tt i vi tin cy

ca mng ng trc.

Cc k thut MPOA (Multiprotocol over ATM - a giao thc trn

ATM), LANE (LAN Emulation - M phng LAN) cng chnh l kt qu

nghin cu gii quyt cc vn , nhng cc gii thut ny u ch gii

quyt c mt phn cc tn ti, nh vn QoS chng hn. Phng thc m

cc k thut ny dng vn l phng thc chng xp, kh nng m rng vn

khng . Hin nay xut hin mt loi k thut IP / ATM khng dng

phng thc xp chng, m dng phng thc chuyn mch nhn, p dng

phng thc tch hp. K thut ny chnh l c s ca MPLS.


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1.4.4. MPLS

K thut ATM tng c coi l nn tng ca mng s a dch v bng

rng (B-ISDN) hay l IP t thanh cng ln trn th trng hin nay, u tn

ti nhc im kh khc phc c. S xut hin ca MPLS - k thut chuyn

mch nhn a giao thc gip chng ta c c s chn la cho cu trc

mng thng tin. Phng php ny dung hp mt cch hu hiu nng lc

iu khin lu lng ca thit b chuyn mch vi tnh linh hot ca b nh

tuyn. MPLS s l phng n cho mng ng trc trong mng th h mi.

MPLS tch chc nng ca IP Router lm hai phn ring bit: chc

nng chuyn gi tin v chc nng iu khin. Phn chc nng chuyn gi tin,

vi nhim v gi gi tin gia cc Router, s dng c ch hon i nhn tng

t nh ATM. Trong MPLS, nhn l mt s c di c nh v khng ph

thuc vo lp mng. K thut hon i nhn v bn cht l vic tm nhn ca

mt gi tin trong mt bng cc nhn xc nh tuyn ca gi v nhn mi

ca n. Vic ny n gin hn nhiu so vi vic x l gi tin theo kiu thng

thng, v do vy, ci thin c kh nng ca thit b. Cc Router s dng

k thut ny c gi l LSR (Label Switch Router). Phn chc nng iu

khin ca MPLS bao gm cc giao thc nh tuyn lp mng vi nhim v

phn phi thng tin gia cc LSR, v th tc gn nhn chuyn thng tin

nh tuyn thnh cc bng nh tuyn cho vic chuyn mch. MPLS c th

hot ng c vi cc giao thc nh tuyn Internet khc nh OSPF (Open

Shortest Path First) v BGP (Border Bateway Protocol). Do MPLS h tr vic

iu khin lu lng v cho php thit lp tuyn c nh, vic m bo cht

l

ng dch v ca cc tuyn l hon ton kh thi. y l mt im v

t trica MPLS so vi cc nh tuyn c in.

Ngoi ra, MPLS cn c c ch chuyn tuyn (Fast Rerouting). Do

MPLS l cng ngh chuyn mch hng kt ni, kh nng b nh hng bi

li ng truyn thng cao hn cc cng ngh khc. Trong khi , cc dch


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v tch hp m MPLS phi h tr li yu cu dung lng cao. Do vy, kh

nng phc hi ca MPLS m bo kh nng cung cp dch v ca mng

khng ph thuc vo c cu khi phc li ca lp vt l bn di.

Bn cnh tin cy, cng ngh MPLS cng khin cho vic qun l

mng c d dng hn. Do MPLS qun l vic chuyn tin theo cc lung

thng tin, cc gi tin thuc mt FEC c th c xc nh bi mt gi tr ca

nhn. Do vy, trong min MPLS, cc thit b o lu lng mng c th da

trn nhn phn loi cc gi tin. Lu lng i qua cc tuyn chuyn mch

nhn (LSP) c gim st mt cch d dng dng RTFM (Real-Time Flow

Measurement). Bng cch gim st lu lng ti cc LSR, nghn lu lng s

c pht hin v v tr xy ra nghn lu lng c th c xc nh nhanh

chng. Tuy nhin, gim st lu lng theo phng php ny khng a ra

c ton b thng tin v cht lng dch v (v d nh tr t im u n

im cui ca min MPLS).

Tm li, MPLS l mt cng ngh chuyn mch IP c kh nng nng

cao cht lng dch v ca mng IP truyn thng. Bn cnh , thng lng

ca mng s c ci thin mt cch r rt. Tuy nhin, tin cy l mt vn

thc tin c th khin vic trin khai MPLS trn mng Internet b chm li.

1.4.5 Ghp knh phn chia theo bc sng WDM v DWDM

WDM (Ghp knh phn chia theo bc sng )v DWDM (Ghp knh

theo bc sng mt cao): Tng bc sng c a vo si quang v tn

hiu c tch ra u nhn. Dung lng tng l tng ca cc tn hiu u

vo, mi tn hiu u v c lp vi tn hiu khc. Mi knh s c mt di tn

c dnh ring cho knh , tt c cc tn hiu n cng mt thi im. Vc bn DWDM ch khc WDM v mt ghp, DWDM c dung lng ln

hn. DWDM cn c mt s tnh nng ng ch khc, bao gm kh nng

khuych i ng thi tt c cc bc sng m khng cn bin i tn hiu

quang thnh tn hiu in trc khi khuych i v kh nng mang cc loi tn


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hiu khc nhau cc tc khc nhau mt cch ng thi v trong sut trn

si quang. DWDM cung cp bng thng ln, tr thnh nn tng ca mng

ton quang cng vi kh nng cung cp bc sng v bo v da trn s

hnh li. Chuyn mch ti lp vt l s cho php thc hin, cc giao thc

nh tuyn s cho php cc tuyn nh sng i qua mng ging nh hot ng

ca knh o hin nay.

Trong cc cng ngh trn hin nay xu hng tch hp IP v mng quang

ang dn c trin khai.

1.5 Xu hng tch hp IP/quang trong mng NGN.

Giao thc Internet (IP) tr thnh giao thc chun ph bin cho cc

dch v mng mi, do lu lng IP s tng nhanh v thay th cc loi giao

thc khc. Trong khi IP c xem nh cng ngh lp mng ph bin th cng

ngh quang tin tin cho php kh nng dung lng truyn dn ln. Vi dung

lng truyn dn ln nh DWDM v kh nng cu hnh mm do ca chuyn

mch quang OXC (optical crossconect) cho php xy dng mng quang

ng hn, nh cc ni kt bng tn ln (lung quang) c th c thit lp

theo nhu cu. Mt trong nhng thch thc quan trng l vn iu khin

cc lung quang ny - tc l pht trin cc c ch v thut ton cho php thit

lp cc lung quang nhanh v cung cp kh nng khi phc khi c s c,

trong khi vn m bo c tnh tng tc gia cc nh cung cp thit b.

Hnh 1-1: Xu hng tch hp cc lp giao thc IP/quang


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Nguyn nhn ch yu gy nn s phc tp trong qun l chnh l s

phn lp theo truyn thng ca cc giao thc mng. Cc mng truyn thng

c rt nhiu lp c lp do c nhiu chc nng chng cho nhau cc lp

v thng xuyn c s mu thun ln nhau cng nh c cc chnh sch khc

nhau. V vy mt trong nhng gii php gim chi ph xy dng v qun l

mng mt cch trit l gim s lp giao thc. Khi dung lng v kh

nng kt ni mng trong c cng ngh IP v quang tng ln, th cng cn thit

ti u mng IP v b qua tt c cc cng ngh lp trung gian to nn mng

Internet quang hiu qu v mm do. Tuy nhin, cc lp trung gian cng cung

cp mt s chc nng c gi tr, nh k thut lu lng (Traffic Enginnering -

TE) v khi phc. Nhng chc nng ny cn phi c gi li trong mng

IP/WDM bng cch a chng ln lp IP hoc xung lp quang hoc tt nht

trn mt lp con ring. Hnh 1-1 minh ho xu hng tch hp cc lp giao

thc IP/quang chnh ang ni ln hin nay.


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Chng 2: Mng IP/WDM

2.1 Gii thiu mng IP/WDM

2.1.1 Gii thiu mng quang WDM

Th h WDM u tin ch cung cp cc lin kt vt l point to point

m ch hn ch trong cc ng trc mng WAN. Cc cu hnh mng WAN

WDM l cu hnh tnh hoc cu hnh nhn cng. Bn thn lin kt WDM ch

cung cp cc kt ni end-to-end tc tng i thp.Nhng vn k thut

ca WDM th h u bao gm thit k v pht trin cc laser v cc b

khuch i WDM, v cc giao thc truy nhp mi trng truyn dn v nh

tuyn bc sng tnh. WADM cng c th c s dng trong cc mng

MAN, v d nh s dng topology ring. lin kt cc ring WADM, b u

cho DXC (Digital Cross Connect) c a ra cung cp cc kt ni bng

hp v bng rng. Thng thng cc h thng ny c dng qun l cc

ng trung k chuyn mch thoi v cc lin kt T1.

WDM th h th 2 c kh nng thit lp lin kt lightpath end-to-end

nh hng trong lp quang nh vic a ra b WSXC. Cc lightpath to nn

mt topology o bn trn topology si vt l. Topo o c th c cu hnh li

mt cch ng p ng li nhng thay i lu lng v/hoc lp k hoch

mng. Cc vn k thut ca WDM th h th 2 bao gm vic a ra cc

thit b tch/ghp v u cho bc sng, kh nng chuyn i bc sng ti

cc b u cho, nh tuyn ng v phn b bc sng. Cng trong th h

th 2 ny, kin trc mng cng nhn c quan tm, c bit l v giao din

lin kt vi cc mng khc. C hai th h u v th h 2 ca mng WDM

c s dng trong cc mng truyn dn ang hot ng. Chi ph hiu qu

ca chng trong cc mng ng di c chp nhn.

Th h th 3 ca mng WDM a ra mt mng chuyn mch gi

quang, trong cc tiu hoc cc nhn quang c gn km vi d liu,


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c truyn i cng vi trng tin, v c x l ti mi chuyn mch quang

WDM. Da trn t l ca thi gian x l tiu gi tin v chi ph truyn dn

gi tin, mng WDM chuyn mch gi c th c thc thi hiu qa s dng

chuyn mch nhn hoc chuyn mch chm quang. Chuyn mch gi quang

thun tu trong cc mng ton quang hin vn ang c nghin cu.

B nh tuyn gi tin ton quang, khng s dng b m mang n mt

lot nhng vn k thut mi cho vic lp k hoch mng: Gii quyt tranh

chp,iu khin lu lng, d phng, tng thch vi cc b nh tuyn IP

truyn thng.

Cc v d ca cc thit b WDM th h th 3 l: Cc b nh tuyn

chuyn mch nhn quang; Cc b nh tuyn quang Gigabit;Cc b chuyn

mch quang tc cao.

Kh nng tng thch gia cc mng WDM v cc mng IP tr thnh

vn chnh cn quan tm trong cc mng WDM th h th 3. nh tuyn

tch hp v phn b bc sng da trn giao thc MPLS/GMPLS bt u

xut hin. Nhng vn k thut phn mm mu cht khc bao gm qun l

bng thng, ti cu hnh v phc hi ng i, v h tr cht lng dch v.

Hnh 2-1 ch ra tin trnh pht trin ca mng WDM. Lu lng li th

hin c th tch ca lu lng v kch thc ca mi lu lng. Lu lng

trong mng truy nhp c ghp knh trc khi c truyn i trn mng

ng trc.


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Hnh 2-1: Tin trnh pht trin mng WDM

2.1.2 Mng IP/WDM

Mng IP cung cp ch mt lp hi t trong mng internet ton cu. IP

l mt b giao thc lp 3 c thit k gii quyt vn tng thch mc

mng v nh tuyn qua nhiu mng con khc nhau vi cc k thut mng lp

2 khc nhau. Do s bng n lu lng IP cho thy rng c s h tng mng

nn c ti u cho IP. Bn di lp IP, si quang s dng k thut WDM l

k thut truyn dn hu tuyn c nhiu ha hn nht, cung cp mt dung

lng mng khng l i hi tn ti trong s pht trin lin tc ca

Internet.

K thut WDM s tr nn hp dn hn khi chi ph ca cc h thng

WDM gim xung. Vi vic ng dng lin tc rng khp trong thng tin cp

si quang v hon thin ca WDM.

ng c thc y phi s dng IP/WDM bao gm:

Cc mng quang WDM c th p ng c vic tng lin tcca lu lng mng bng cch s dng c s h tng mng hin


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Lun vn cao hc - 17- Tiu Xun Hng_______________________________________________________________

c. Vic s dng k thut WDM lm tng ng k bng thng

mng quang.

Phn ln l

u l

ng d liu mng l IP. Gn nh

ton b d liung dng ngi dng cui l s dng IP. Lu lng thoi truyn

thng cng c gi ho.

IP/WDMtha hng tnh linh hot v kh nng thch nghi trongcc giao thc iu khin IP

IP/WDMc th t c phn b bng thng theo yu cu c dphng, thi gian thc .

IP/WDMs gii quyt c vn tng thch WDM vi dch vqua s gip ca cc giao thc IP

Trn quan im dch v mng IP/WDM c th tn dng u imca cc c ch, m hnh, chnh sch cht lng dch v.

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

WDM. Hnh 2-2. ch ra vic truyn dn gi tin IP hoc cc tn hiu

SONET/SDH trn cc mng WDM.

Hnh 2-2: Truyn dn gi tin trn cc bc sng


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Nhng vn ca mng IP/WDM

IP/WDM tr thnh thc t cho tt c cc dch v end-to-end c cung

cp hon ton bng quang. Do mng quang cn hon thin nhng yu cu

v tnh nng nh pht hin v chng li, qun l iu khin mng, nh tuyn

bc sng, chuyn mch quangtrong bn thn lp WDM (thng c xem

nh l lp 1).

2.2 Cc kin trc mng IP/WDM

2.2.1 Cc kiu kin trc mng

K thut mng IP/WDM c th c chia thnh 2 loi: WDM c th

cu hnh li v WDM chuyn mch.Loi u c s dng trong chuyn mch knh trong ng quang

c to bi cc knh c thit lp c kh nng cu hnh li phn ng

li nhng thay i ca lu lng, quy hoch mng.

Loi th hai c s dng trong mng WDM chuyn mch gi, trong

cc tiu quang hoc nhn quang c c nh km vi d liu, c

truyn i cng trng tin v c x l ti mi chuyn mch.

K thut WDM c th cu hnh li

c s dng trong cc mng truyndn ng trc. N ch yu gii quyt n vn lin quan ti lu lng ln,

tuy nhin lu lng ny t bng n hn so vi mng truy nhp. WDM chuyn

mch s pht trin c bit trong cc mng truy nhp v mng metro. WDM

chuyn mch nhm n mc ch chuyn mch lu lng trung bnh, chng

i hi kim trc mng linh hot v cn nhng tnh nng iu khin mng

ton din v c th thay i v quy m.

V IP tr thnh lp hi t duy nht trong mng my tnh v mngvin thng nn vn hiu sut v hiu qu truyn dn lu lng IP trong mt

mng WDM l vic rt quan trng. Ta xt ba kiu kin trc mng IP/WDM


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2.2.1.1 Mng IP/ WDM im-im

Trong kiu kin trc ny cc lin kt quang im- im WDM c s

dng cung cp cc dch v truyn dn lu lng IP. Cc thit b WDM nh

OAWDM khng th t chng to nn mt mng. Thay vo chng cung cp

mt lin kt lp vt l gia cc b nh tuyn IP. SONET c th c s dng

cho truyn dn cc khung trn cc knh WDM. Cc gi tin IP c th c

ng thnh cc khung SONET s dng c ch Packet-over-SONET.

Rt nhiu b nh tuyn IP v nh cung cp thit b WDM hin c

nhng sn phm c th h tr IP over point-to-point WDM. Cc h thng

Ip/wdmim- im c trin khai rng ri trong cc mng ng di.

Mt kin trc IP/WDM im-im i hi b nh tuyn IP c kt

ni trc tip vi nhau thng qua cc lin kt si quang a bc sng . Trong

b nh tuyn Topo mng trong kiu kin trc ny l c nh v tt c

nhng cu hnh mng l tnh. Cc h thng qun l cho nhng mng nh th

ny l thng tp trung, vi tng tc ti thiu gia cc lp IP v lp WDM.

2.2.1.2 Mng IP/WDM c kh nng cu hnh li

Trong kin trc ny cc giao din ca cc b nh tuyn IP

c kt nivi cc giao din client ca mng WDM. Trong kin trc ny cc kt ni

cho WDM v cc giao din tch/ ghp knh t bn thn chng c kt ni

vi cc si quang kt ni a bc sng. Do bn thn mng WDM c mt topo

vt l v mt topo ng quang. Topo vt l bao gm cc phn t mng lin

kt vi nhau bi cc si quang, topo ng quang to nn bi cc kt ni knh

bc sng.

WDM c th thit lp ti cu hnh l mt k thut chuyn mch knh do vic thit lp v gii phng knh bc sng c tin hnh trong cc pha

ring bit. C mt ch quan trng l vic chuyn mch lu lng IP v

chuyn mch bc sng khng bao gi hot ng trn cng mt lp trong m

hnh qua mng c kh nng ti cu hnh. Cc ng quang trong mng WDM


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c thit k thch hp vi topo IP , bng cch cu hnh thch hp cc u

cho WDM, mt giao din b nh tuyn cho trc c th c kt ni ti bt

c giao din nh tuyn no ca mi b nh tuyn khc. Kt qu l b nh

tuyn gn k ca giao din cho trc c th cu hnh li c trong kiu kin

trc ny. Mng vt l c th h tr mt s lng topo o tun theo nhng

rng buc ti nguyn mng ging nhau.

2.2.1.3 Mng IP/WDM c kh nng chuyn mch

Trong kin trc IP/WDM c kh nng chuyn mch, c s h tng

WDM h tr trc tip kh nng chuyn mch gi. C nhiu phng php c

xut bao gm:

Chuyn mch chm quang (OBS-Optical Burst Switch)

Chuyn mch nhn quang (OLS-Optical label Switching)

Chuyn mch gi quang (OPR- Optical Packet Routing)

OBS v OLS s dng m hnh chuyn mch fat-packet/flow khc so vi

nh tuyn gi tin IP truyn thng. Bn thn nh tuyn IP s dng a ch

ch, OLS tng t nh MPLSn khng h tr vic chuyn tip gi tin IP da

trn a ch ch. OBS v OLS khng hiu

c cc tiu gi tin IP v do khng th chuyn tip gi tin IP. OBS v OLS thch hp vi lu lng li

trung bnh thay v lu lng li nh hin c trong cc mng IP truyn thng.

OPR th hin thc s quang hc ca b nh tuyn IP truyn thng do

vy h tr y nhng tnh nng IP. V cc k thut x l logic quang hc

v lu m d liu quang hin cha c hon thin, cc h thng WDM

chuyn mch thng khng s dng b m, nhng ng dy tr quang c

s dng. Cc h thng ny da trn x l tiu ca gi tin iu khin hotng ca chuyn mch.

Ta xt cu trc hai chuyn mch quang c th: Chuyn mch chm

quang v chuyn mch gi quang.


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Chuyn mch chm quang (OBS)

Trong OBS, tiu gi iu khin c gi i theo ng iu khin

trc khi gi d liu quang thc s c gi i. tng y l tiu iu

khin s n cc node chuyn mch trung gian trc, cho php mi chuyn

mch thc hin cc tnh ton quyt nh chuyn mch v ci t thit lp u

cho ch ngay trc khi gi tin d liu thc s n. Theo cch ny, gi tin d

liu quang lch qua t cng hng vo n cng hng ra. tr gia cc

tiu iu khin v gi tin d liu tng khi s chng v tr x l ti cc

chuyn mch gia tng. Hnh 2-3 th hin hot ng ca mt node WDM

chuyn mch chm quang nhvy.

Hnh 2-3: Chuyn mch chm quang

Chuyn mch chm quang s dng mt ng dnh trc mt chiutheo mt ngun gi yu cu thit lp v sau gi thng tin chm m

khng phi i xc nhn thit lp. iu ny l do thc t l thi gian truyn

dn c th rt ngn.


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Chuyn mch gi quang (OPR)

Trong chuyn mch gi quang tiu iu khin gi tin cng c th

c coi nh l nhn, thng c gi i cng vi gi d liu theo cng mt

ng. cho php thi gian cn thit cho tnh ton quyt nh chuyn mch

v ci t thit lp u ni cho, gi tin d liu lun c dn qua mt ng

tr quang trong lc mt chuyn mch trung gian. Gi tr tr c la

chn do gi tin d liu xut hin t ng dy tr quang, thit lp u cho

quang mong mun c ci t. Gi tr tr ny cc b v khng i ti mi

node chuyn mch trung gian, khng phc thuc ng i c th ca nhng

gi tin. Hnh 2-4 th hin hot ng ca mt h thng WDM chuyn mch giquang nh vy.

Hnh 2-4: Chuyn mch gi quang

Cc gi tin trong mng quang c th c di c nh (v d nh t bo

ATM) hoc thay i (v d nh gi tin IP). Mt gi tin c di thay i a

vo mng trong mng t thng tin iu khin hn do vy c hiu xut cao hn.

Tuy nhin kch thc gi tin khng th qu ln t nht l phi nh hn dung


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lng ca ng dy tr quang. Vic la chn di gi tin c da trn

nhng c tnh ng dng v lu lng.

C hai c ch chuyn tip trong mng chuyn mch gi quang:Datagram v knh o. Trong c ch chuyn tip datagram tiu gi tin c

th c vn chuyn trong bng hay ngoi bng, c xem xt mi node

trung gian v khng c khong thi gian trng no v phn trng tin v phn

tiu c truyn cng nhau. C ch ny c dng trong truyn gi IP.

Trong c ch chuyn tip knh o, cc knh o c thit lp trc khi gi tin

c chuyn i qua chng. Knh y l o v n khng dnh trc bt k

mt bng thng no. Knh o c mt bng chuyn mch, kt hp mt s nh

dng knh o u vo vi mt cng u ra. Theo cch nh vy n tch bit

phn nh tuyn khi phn chuyn tip. Cc knh o thit lp trc c s

dng trong sut thi gian chuyn tip.

Hnh 2-5 th hin cc mng IP qua mng WDM chuyn mch. OBS v

OLS c biu din l OLSR.

Hnh 2-5: IP qua mng chuyn mch WDM


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S khc nhau chnh gia OBS v OLS OBS s dng chuyn mch Fat-

packet nhng OLS s dng chuyn mch tiu lung. OLSR thng c

trin khai thnh mt nhm, trong nhm ny ch OLSR bin i hi vic thc

thi ca ton b chng giao thc IP. OLSR bin cng cung cp lu m nh

vy cc gi tin IP n c th ch trong hng i ti pha bin trong trng hp

thit lp LSP ng.

Cc OLSR c lin kt vi nhau bng cc si quang h tr cc knh

a bc sng. OPR c th c s dng ch lm cc b nh tuyn IP.

Ba kiu kin trc c trnh by trn c lin kt vi nhng phn

cng v phn mm iu khin gim st khc nhau. Trong thc t kiu kin

trc mng Ip/wdmim- im s dn c thay th bi hai kiu kin trc cn

li do chng cung cp nhiu tnh nng, kh nng cung cp hiu dng ti

nguyn mng cao hn, chi ph vn hnh thp hn. Do vy ta s tp trung

nghin cu kin trc mng IP/WDM c th cu hnh v chuyn mch.

2.2.2 Cc m hnh lin kt mng IP/WDM

Phn trc chng ta nghin cu cc kin trc cho vic xy dng mng

IP/WDM thng qua vic kt ni cc b nh tuyn IP thng thng vi cc

thit b WDM. Trong phn ny s miu t cch thc mng IP v mng WDM

kt ni vi nhau theo nhng kin trc ny.

2.2.2.1 IP/ WDM c th cu hnh.

Trong mt phng d liu kin trc IP qua mng quang c kh nng ti

cu hnh s lun to nn mt mng chng ln (overlay) trong cc IP c

truyn qua cc ng quang WDM. Nhng knh ny khng phi l nhng

ng i o nh

trong MPLS. Khi cc gi tin n mt giao din OADMclient, ng quang tng ng c thit lp sn. Vic i qua ca ng

quang ny m bo rng gi tin IP chuyn qua mng WDM m khng c bt

c s kim tra no trong mt phng d liu. Thc t gi tin IP thm ch khng

nhn bit c vic s dng k thut truyn dn no c th. N ch bit c


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mt lin kt IP gia cc b nh tuyn. Trong trng hp ny. IP/WDM tng

t nh IP qua mt k thut lp 2 bt k no v d nh ATM hay frame relay.

Trong mt phng iu khin ta xem xt 3 m hnh lin kt: Chng ln

(overlay), gia tng augmented), v ngang hng (peer to peer).

M hnh iu khin chng ln

Theo cc m hnh mng chng ln, cc mng IP to nn lp client

cc mng WDM ng vai tr nh l nh cung cp dch v mng truyn dn

vt l. Mt mng WDM c ring h thng qun l iu khin ca n. N c

th iu khin tp trung hoc phn tn, c k hoch nh a ch IP ring.

s dng giao thc iu khin IP cho cc mng WDM, mt phn t mng

WDM phi c mt a ch IP, nhng a ch IP ch c th thy bn trong

mng WDM. Cc giao thc nh tuyn, phn b v phc hi topo mng, bo

hiu trong mng IP s c lp so vi mng WDM. M hnh qun l mng

chng ln c ch ra trn hnh 2-6.

Hnh 2-6: M hnh iu khin NMS chng ln

Trong m hnh ny c mt knh d liu DCN cho mng WDM. DCN

cung cp cc chc nng iu khin knh qun l WDM, c c th c truy

nhp bi cc b nh tuyn IP.

Accesslink

WADM

WADMOCX

WADM

WADM WADMOCX

WADM

WDM NMS

LpWDM


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M hnh iu khin gia tng:

Trong m hnh ny thng tin v kh nng iu khin c th n c

mt node c chia s gia mng IP v mng WDM. Cc phn t mng

WDM c nh a ch IP v a ch IP ny l xc nh duy nht trong ton

mng. C mng IP v WDM c th s dng cng IGP v d nh OSPF, nhng

nhng trng hp nh tuyn ny l phn bit trong min IP v min quang.

Do m hnh gia tng thc s l mt m hnh IP lin min (inter-domain).

S tng tc gia IP v WDM c th tun theo mt giao thc EGP v d nh

giao thc BGP. Giao thc OSPF cho cc mng WDM v giao thc BGP quang

i hi vic m rng quang i vi nhng bn sao ca chng trong nh tuynIP truyn thng. Bo hiu gia mng IP v WDM cng tun theo mt m hnh

lin min. Da trn chnh sch c nh ngha to bin WDM, vn giao

thc bo hiu y c th c thc thi bi IP v WDM do mt trng hp

bo hiu c th di chuyn qua mng IP v WDM.

Hnh 2-7: M hnh iu khin gia tng

OpticalEGP

EGP

WADM

WADMOCX

WADM

WADM WADMOCX

WADMOpticalIGP

MngIP a Mng

IP b

IGP bIGP a

MngWDM c

OpticalEGP

OpticalEGP

OpticalEGP


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Lun vn cao hc -27- Tiu Xun Hng_______________________________________________________________

Hnh 2-7 th hin m hnh IP/WDM gia tng. Trong hnh v ny bao

gm 3 mng, mng IP a v b v mng WDM c. Hai mng IP c iu khin

bi nhng IGP trng hp ring bit, v mng WDM c iu khin bi mt

phin bn ca IGP cho mng quang. Hai mng IP c kt ni trc tip vi

nhau s dng EGP. Mng IP v mng WDM c kt ni vi nhau s dng

EGP quang.

M hnh iu khin ngang hng:

Theo m hnh iu khin ngang hng, thng tin v kh nng c th n

ch c chia s gia mng IP v mng WDM v ch mt trng hp nh

tuyn chy trn c hai mng IP v WDM. Trong mt phng iu khin, cc b

chuyn mch WDM c xem nh l cc b nh tuyn IP vi mt quan h

ngang hng (peer-to-peer). Vy mng IP v WDM c tch hp thnh mt

mng trn phng din iu khin qun l v iu khin lu lng. M hnh

ngang hng c ch ra trn hnh 2-8.

Hnh 2-8: M hnh iu khin ngang hng

IGP

WADM

WADMOCX

WADM

WADM WADMOCX

WADM

MngIP/WDM


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Ba m hnh lin kt mng c trnh by trn khc nhau v mc

tch hp ca IP/WDM. Mt mt, m hnh chng ln s dng NMS cung

cp mt giao din trc tip gia mng IP v WDM; mt khc, m hnh ngang

hng ha hn mt lin kt lin mch gia cc b nh tuyn IP v WDM trong

mt phng iu khin. M hnh chng ln c v nh thch hp cho k hoch

trin khai ngn hn mt cch nhanh chng ca cc mng tng i tnh

IP/WDM. Bi v cc cu trc iu khin v qun l ca chng nhn chung l

n gin, cc m hnh ngang hng v thch hp c v nh thch hp cho k

hoch trin khai di hn ca IP/WDM c ng cao. Vic la chn m hnh

kin trc lin kt mng cng c da trn mi trng mng hin ti, quyn

s hu mng, v quyn qun l mng.

C nhiu kh nng l c ba m hnh ny s cng tn ti trong tng lai.

Ta c th cm thy rng cch tip cn ngang hng l c hiu qu nht. Nhng

vic ti u ho tht s l n by ca mng vt l khng ng nht. Nh vy,

v cc l do tr thp v hiu sut cao, mt mng ti u c th c c tnh

t v tr l mt mng chuyn mch tc cao. Mt mng nh vy s c

trin khai thnh mt nhm(cluster).Tt nhin n to nn mt mng chng ln

ln cc mng IP khc.

2.2.2.2 IP/WDM c kh nng chuyn mch

OBS v OLS c th c trin khai bng cch s dng OLSR. Trong

phn ny ta s xem xt IP over OLSR v IP over OPR.

IP over OLSR:

OLSR cung cp mt c ch chuyn tip nhn, n v bn cht l mt

mng chuyn mch gi. Tuy nhin v gi quang khng phi l gi IP v n ctiu ring, n cn c to ra ti OLSR bin. Do , OLSR cn phi c

trin khai thnh mt nhm nhm mc ch li dng u im ca tit kim chi

ph bng thng v giao din. OLSR li ch l mt chuyn mch lp 2 khc v

n khng cn phi thc hin cc chc nng mt phng d liu IP.


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h tr mt mt phng iu khin IP tp trung v hp nht, OLSR c

th c nh a ch IP nh n c th h tr nh tuyn IP v bo hiu.

Trong mt phng d liu, IP over OLSR s lun to thnh mt mng chng

ln, trong cc gi tin IP c ng gi thnh cc gi quang ti OLSR bin.

Tuy nhin, OLSR linh hot hn so vi OXC v mi gi quang b kim tra ti

chng trung gian. Ngoi ra, ng chuyn mch nhn LSP trong phn cp

chuyn tip l mt ng o, n s dng c ch iu khin trng thi mm

duy tr trng thi ca n. Mt ng o khng cn phi dnh trc bng thng

v c th gii quyt c vn truyn dn lu lng li nh hn.

Hnh 2-9 ch ra mng IP over OLSR. Nh c ch ra trong hnh v, cc

gi tin IP c tp trung ti bin ca mng OLSR. Bn trong mng OLSR, cc

gi tin quang c chuyn tip da trn nhn (tc l tiu gi tin quang) m

chng mang theo.

Hnh 2-9: Mng IP over OLSR

Trong mt phng iu khin, mt OLSR c th c thc hin bng

cch s dng hoc l OBS hoc l OLS. Sau y ta s dng OLS trin khai

OLSR. Hn na, khi nim nhn ca OLS l tng t nh ca MPLS. i vi

Nhn quang

OLSR

OLSROLSR

OLSR OLSR

OLSR

Gi IP

Gi IP

Gi IP

Mng OLSR


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vic thit lp ng o v phn b nhn, OLS c th dnh ring mt knh

bc sng vn chuyn thng tin iu khin. Nhm OLSR c th c iu

khin bng giao thc OSPF vi nhng m rng cho mng quang. V OLSR s

dng mt a ch IP, mng IP v mng OLSR c th h tr mt mt phng

iu khin hp nht, tc l MPLS. Mt giao thc bo hiu chung, v d nh

RSVP hoc LDP ca MPLS c th c s dng cho vic thit lp ng i v

phn b nhn qua mng IP v OLSR.

V mt kh nng tng thch nh tuyn, IP over OLSR c th h tr

mt trong nhng cu hnh sau:

- Mt trng hp nh tuyn IGP c dng cho mng OLSR, n s

tng thch vi cc mng IP khc s dng EGP. iu ny em li mt m

hnh nh tuyn lin min.

- Mt trng hp nh tuyn n IGP iu khin c mng OLSR v IP.

iu ny tng ng vi mt m hnh nh tuyn ngang hng (peer-to-peer).

Tuy nhin, n i hi phi sa i li IGP hin ti. V d nh mng OLSR c

th c cu hnh nh l mt vng nh tuyn theo giao thc OSPF, c ngha

l flooding bn tin trng thi ng truyn (LSA) lin min cn c cp nht

vi nhng m rng OLSR, v flooding LSA ni b vng OLSR cng c th

cn c sa i truyn dn c hiu qu thng tin trng thi lin kt

WDM.

Ni tm li, cu hnh th nht i hi s m rng ca IP EGP tiu

chun, trong cu hnh th hai cn c m rng IP IGP tiu chun.

IP over OPR

IP over OPR v bn cht l mt mng IP. Mng internet quang to nnt OPR c th c c trng bi mt s knh nh sng song song gia cc b

nh tuyn lin k. Nh trong IP thng thng, khng c s phn cch r rng

gia knh d liu hng lu lng (traffic-oriented) v knh iu khin. Tuy

nhin, vic s dng MPLS c th phn bit c v cc ng cut-through v


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ng u tin c th c thit lp trnh tc nghn. Nhng c ch QoS tr

thnh mt phn thit yu ca mng IP.

Mt vn then cht cho nh cung cp OPR l mc nhng tnh nng

ca b nh tuyn nn c trin khai trong min quang. Cu tr li lin quan

n nhng c im ng dng, hiu sut v chi ph. Trong mt phng d liu,

cc b nh tuyn IP v OPR c quan h ngang hng, trong c hai u c

th chuyn tip cc gi tin IP th.

Trong mt phng iu khin, cc b nh tuyn IP v OPR cng to nn

mt quan h ngang hng s dng iu khin trong bng. Vic lin kt cc b

nh tuyn IP v OPR tun theo gii php IP thng thng. Theo , i vi

mc ch nh tuyn, mt nhm cc mng v b nh tuyn c iu khin

bi mt nh qun l c nhm thnh mt h thng t tr (AS). Cc b nh

tuyn trong mt AS c t la chn c ch cho vic phc hi topology, xy

dng v duy tr c s thng tin nh tuyn, v tnh ton ng i. C ch ny

trong phm vi AS s dng IGP. Gia mt cp AS, EGP c s dng trao

i thng tin v tnh kh dng v c th n c ch ca mng.

nhn mnh Internet quang vi k thut WDM, cc giao thc IP

truyn thng cn phi c sa i, m rng gii quyt nhng vn lin

quan n IP/WDM. V d, c mt s cng bc sng/si quang trn trng

OPR v vn t ra y l bng cch no s dng cc a ch IP mt cch

hiu qu v thit thc. Mt v d ca nh a ch OPR tn dng b lin kt do

ch mt cp a ch IP c cung cp cho cc knh lin kt gia mt cp

OPR.

Hnh 2-10 th hin mt vi cu hnh mng c th thc hin

c ca bnh tuyn IP v OPR. AS trn cng trong hnh v th hin mt mng lai ghp

s dng b nh tuyn IP v OPR; AS di cng bao gm cc b nh tuyn

quang.


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Hnh 2-10: Mng IP over OPR

2-3 Kt lun

Trong chung ny ta xem xt cc kiu kin trc mng IP/WDM da

trn nhng cng ngh WDM hin c. Mt mng WDM c kh nng ti cu

hnh h tr chuyn mch knh, trong khi mt mng WDM chuyn mch tun

theo c chchuyn mch gi. Nhng v d ca WDM chuyn mch l OBS,

OLS, OPR.Mc ch ca WDM chuyn mch l c mt mng n gin, tr thp

tn dng u im ca mng ton quang cung nh khai thc nhng li ch

ca chuyn mch gi.

Hin nay cng ngh mng WDM IP over Point- to-point c s dng

trong mng ng di backbone v cc mi trng mng MAN.

Cc mng WDM chuyn mch vn ang nghin cu nhng m hnh th

nghim. Mt vi k thut ct yu vn cha c hon thin nh lu mquang, thi gian x l, chuyn mch gi quang cn di.

Vic la chn nhng m hnh lin kt IP/WDM mc ch l la chn

cch mng IP v mng quang c th lin thng c vi nhau. T ta c

OPR

EGP

EGP

EGP

OPR

OPROPR

OPR OPR

IGP a

OPR


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3 m hnh lin kt: M hnh iu khin chng ln, m hnh iu khin ngang

hng v m hnh iu khin gia tng l s tho hip t hai m hnh trn.


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Chng 3: iu khin mng trong mng IP /WDMTrong chng ny chng ta s tp trung vo nhm chc nng iu

khin mng. Nhm chc nng iu khin mng lin quan ti cc c ch iu

khin qua mng phn bit vi nhm chc nng iu khin lu lng lin quan

ti vic ti u ho vic s dng mng IP/WDM.

Hnh 3-1 ch ra mt nguyn tc chung ca iu khin lu lng v iu

khin mng trong cc mng IP/WDM .

Hnh 3-1:iu khin lu lng v in khin mng IP/WDM

iu khin lu lng IP/WDM gii quyt nhng vn hiu qu v

hiu sut lu lng nh tuyn trn mt topo ng truyn quang IP c

thit lp trc, trnh c nhng lin kt tc nghn v cn bng ti gia nhng

ng i. Trong trng hp WDM c kh nng ti cu hnh, n cng gii

quyt vn thit k ti u topo IP tn dng u im ca tnh nng ti cu

hnh WDM. Kh nng ti cu hnh cng c p dng cho tng knh quang

tng ng o v d do suy gim tn hiu, mo dng, hoc nh tuyn li yu

cu.

K thut lu lng IP/WDM

IP-TE: MPLS-TE WDM-TE: MPS-TE

iu khin mng IP/WDM

K mng IP: OSPF,RSVP

Mng WDMMng IP

K mng WDM:OSPF o tical


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gn kt cc thit b mng vi nhau v h tr thun li cho iu khin

lu lng, mt lp iu khin mng to ra trn tng phn t mng v lin kt

cc si quang - lp truyn dn vt l. iu khin mng chng ta cp n

cc giao thc mng OSPF (IGP) v BGP (EGP) v cc bn tin ICMP, RSPV.

iu khin mng IP/WDM c nhng phn sau:

nh a ch IP/WDM Pht hin topo mng nh tuyn IP/WDM Thit lp v gii phng lin kt C ch bo hiu iu khin truy nhp mng WDM Bo v v phc hi mng IP/WDM

Kin trc phn mm ca iu khin mng IP/WDM bao gm:

Mt giao thc qun l v iu khin chuyn mch cung cp giao din

qun l gia cc thnh phn iu khin mng v cc chuyn mch quang;

Cc module nh tuyn, pht hin topo mng v bo hiu l cc thnh

phn chnh trong iu khin mng, chng hot ng theo chiu ngang lin

kt cc tin trnh ngang hng vi nhau.

Nu IP v WDM to nn mt mng chng ln trong mt phng iu

khin th cn phi c mt server phn gii a ch, n khng phc thuc

vo cc module iu khin khc v c th trin khai theo kiu tp trung hoc

phn tn. Giao thc qun l v iu khin mng c th cng t mt v tr vi

iu khin chuyn mch, trong khi server phn gii a ch c th t bt k

u trong mng. Nu IP v WDM to nn mt mng chng ln trong mt

phng d liu th ta cng cn phi c mt thnh phn iu khin truy nhp

WDM. Thnh phn ny lun lun c t ti chuyn mch WDM bin.


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3.1 a ch mng IP/WDM

nh a ch mng IP/WDM mc ch m bo tnh lin thng gia

cc mng IP v mng WDM . Nhng thc th c th nh a ch trong mng

WDM bao gm: giao din chuyn mch, cc lin kt quang, cc si vt l, v

cc knh bc sng. Vn y l vic nh danh lin quan n iu khin

mng lin quan. C ch nh danh phi cung cp c tnh k thut ca cc

im kt cui trong mng WDM vi lu lng thch hp khi cc ng quang

c thit lp (V d mt OXC c th c nhiu giao din truyn dn, mi

giao din ng vi s knh bc sng, c th c nhiu i cp si quang gia

mi cp chuyn mch). Do vy s khng hp l khi cho rng mi knh bc

sng hoc cng u cui phi c mt a ch IP duy nht. Ngoi ra, vic nh

tuyn ca mt ng quang bn trong mng WDM c th khng ph thuc

vo thng tin im u cui mt cch chnh xc, nhng ph thuc vo cc

kt cui OXC.

Vic xc nh c th hn ca cc im u cui tng ng cc OXC

kt cui ch khng phi OXC trung gian. iu ny rt ra c ch nh danh

nh cc OXC c xc nh bng a ch IP duy nht, v b chn lc xc

nh chnh xc hn na thng tin lin quan n mt OXC.

Bn trong mng WDM, vic thit lp cc phn on ng quang gia

cc OXC cnh nhau i hi vic nhn dng knh cng c th, hoc thm ch

knh con. Vi mt mt phng iu khin da trn MPLS, mt nhn c th

thc hin chc nng ny. Cu trc ca nhn quang c thit k theo cch m

n c th m ho tt c cc thng tin yu cu.

Mt thc th khc nhn dng cho mt nhm lin kt quang cng

chia s ti nguyn vt l. V d cc knh ton quang c nh tuyn trn

cng mt si cc quang c th cng mt nhm lin kt.

Cui cng, cc kt ni quang gia cc OXC cnh nhau c th c

nhm li thng bo trong mt giao thc trng thi lin kt. Cc kt ni


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thnh phn trong mt nhm phi c th xc nh c. Khi cp n vn

xc nh nhm lin kt, thng tin ny l cn thit cho vic tnh ton chnh xc

ng i.

Trong mt mng IP/WDM chng ln, lp WDM c c ch nh a

ch sao cho cc a ch lp 2 nh x vi a ch lp 3 cn c mt giao thc

phn gii a ch. M hnh IP/WDM ngang hng h tr mt phng iu khin

hp nht, theo lp IP cng nh lp WDM u s dng a ch IP. Mt c

ch nh a ch hp nht cho mng IP/WDM hiu qu v mm do hn. Hn

na vic nh a ch trong lp WDM tn dng c ch iu khin nh giao

thc nh tuyn v bo hiu c pht trin trong mi trng IP. h tr

mt phng iu khin ngang hng chung, c hai mng IP v WDM c a ch

IP ton cc.

nh a ch chng ln

Mt mng IP/WDM chng ln c th dng a ch IP trong lp IP v

lp WDM, nhng a ch ny trong cc lp khc nhau khng th nhn thy

nhau. Do vy cn phi c mt c ch nh x gia cc a ch lp IP v cc a

ch lp WDM. Lp IP c th c iu khin bi giao thc IGP; lp WDM c

th c iu khin bi giao thc OSPF vi phn m rng cho WDM. IP

OSPF v OSPF quang l cc tin trnh OSPF ring bit.

Trong lp WDM knh iu khin c tch bit khi knh d liu.

Mt knh ngoi bng c dng truyn dn cc bn tin iu khin, trong

cc giao din phn t mng WDM c th s dng cc a ch vt l; knh

iu khin lin quan n mt hoc nhiu knh d liu kt ni gia hai phn t

mng WDM. Mt b lin kt v mt tp hp ca tt c cc nhm kt ni giacc cp chuyn mnh cnh nhau. Mt nhm lin kt c xc nh bi mt ID

c th c to nn bi cc lin kt theo tiu chun sau:


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Cc lin kt c trong cng mt nhm lin kt c s dng trongqun l li v bo v, phc hi mng, l mt ID ca mt nhm

lin kt quang chia s ti nguyn vt l.. Cc lin kt c cng mt nh dng m ho v d OC-192 Cc lin kt c cng loi bo v.

Vic nhm li cc lin kt gip tit kim a ch IP, gim s lng nh

tuyn gn k gia cc node cnh nhau. Thng tin trng thi lin kt ca knh

d liu c flood trong knh iu khin s dng giao thc OSPF cho mt

LSA khng trong sut. Mt lin kt IP trong knh d liu c lin kt vi

mt knh bc sng hai chiu. a ch IP lp WDM c th c gn cho mtlin kt WDM hng ra ti chuyn mch gn k n.

Knh iu khin lp WDM c gn cc a ch IP. C cc b chuyn

mch quang c lin kt vi nhau bng cc lin kt WDM. Kiu nh a ch

ny thch hp cho mng IP/WDM c th cu hnh trong khng c chc

nng mt phng d liu IP trong WDM.

nh a ch ngang hng

Trong mng IP/WDM c th cu hnh c th s dng m hnh nganghng trong mt phng iu khin, trong cc chuyn mch c nh a

ch IP lp WDM l ngang hng vi b nh tuyn IP. V WDM c kh nng

ti cu hnh ch c th h tr chuyn mch knh, nn khng cn thit h tr

tnh nng IP trong mt phng d liu WDM. nh a ch IP lp WDM

tng t nh nh a ch chng ln ngoi tr l a ch WDM c mt quan h

ngang hng vi mt a ch mng IP (tc l c mt a ch IP ton cc cho

thit b WDM). Lp WDM c th p dng vic cc b lin kt gn cp ach IP cho lin kt gia hai chuyn mch gn nhau.

Trong mng IP/WDM chuyn mch lun h tr nh a ch ngang

hng trong mt phng d liu. Mt mng IP over OLSR c mt phng chuyn

tip d liu c lp, khc vi chuyn tip d liu IP da trn a ch ch.


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IP over OPR to nn mt mng ngang hng gia IP v WDM trong c

mt phng d liu v mt phng iu khin. Trong mi trng hp vic nhm

cc lin kt c s dng thit kim a ch IP v giao thc nh tuyn gn

k.

3.2 Nhn bit topo mng.

Vic nh tuyn trong min WDM da trn kin thc v topo mng v

tnh kh dng ti nguyn mng. Bc u tin vi mc ch xc nh trng

thi lin kt din rng (cho mi OXC) l pht hin ra trng thi ca nhng lin

kt ni b vi cc OXC gn k, c th mi OXC phi xc nh trng thi

Up/Down ca tng lin kt quang, bng thng, cc tham s lin quan n lin

kt, s cng u xa. Thng tin sau cng ny c th c s dng ch r mt

nhn quang tng ng trong qu trnh bo hiu gim st ng quang.

Vic xc nh nhng tham s ny da trn giao thc nh tuyn t ng

hay giao thc nh tuyn tnh ang hot ng gia 2 OXC cnh nhau. Cc c

tnh ca nhng giao thc ny c th ph thuc vo loi OXC gn k (v d

trong sut hay khng trong sut). Ni chung, loi giao thc ny c th coi nh

l mt giao thc NDP (Neighbour Discovery Protocol), mc d cc chc nng

qun l nh qun l lin kt v cch ly li c th c tin hnh nh l mt

phn ca giao thc. Giao thc qun l lin kt (LMP Link Management

Protocol) l mt v d ca NDP.

Mt giao thc NDP thng yu cu lin lc trong bng trn cc knh d

liu xc nh trng thi lin kt v kt ni ni b. Trong trng hp ca

nhng OXC khng trong sut vi u cui SONET, mt tin trnh ca NDP c

th chy trn mi cng OXC, lin lc vi tin trnh NDP tng ng ti OXC

gn k. Giao thc ny c th s dng cc byte tiu SONET truyn dn

nhng thuc tnh ni b (cu hnh) n hng xm ca n mt cch nh k.

Do , 2 chuyn mch gn nhau c th t ng xc nh nh danh ca nhau


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v ca kt ni ni b, v cng theo di trng thi up/down ca cc lin kt ni

b.

Nhn bit topo mng l mt th tc m theo trng thi ti nguyn v

topo mng ca tt c cc lin kt trong mng c xc nh. Nhn bit topo

mng c th c thc hin bng cch s dng mt giao thc nh tuyn trng

thi lin kt (OSPF hay IS-IS), hoc n c th c dn ng qua nhiu giao

din qun l (trong trng hp tnh ton ng i tp trung). n y ta s tp

trung vo vic tnh ton ng i phn tn s dng mt giao thc trng thi

lin kt IP.

Phn ln tnh nng nh tuyn trng thi lin kt trong mng IP c th

p dng cho mng WDM. Tuy nhin, s hin din ca cc lin kt quang v

ca cc knh bc sng, cng nh l cc tham s cht lng dch v tn hiu

quang, i hi nhng thay i thng tin trng thi lin kt. Nhng thay i c

th ny l:

Thng tin trng thi lin kt c th bao gm cc b lin kt. Mi b lin

kt c th hin nh l mt lin kt tru tng trong topo mng. C th biu

din nhiu b lin kt khc nhau.V d, nhng tham s ca lin kt tru tng

c th bao gm s lng, bng thng v loi ca cc lin kt quang bn trong

b lin kt.

Thng tin trng thi lin kt phi lu gi li cc tham s lin quan n

hi phc ca cc lin kt quang. V d v cc tham s ny bao gm loi bo

v kt ni v danh sch cc nhm lin kt cho mi kt ni.

Mt nh tuyn gn k n c duy tr gia cc hng xm, gia chng

c th c nhiu lin kt quang hoc nhiu b lin kt. iu ny gip gim

c byte mo u ca bn tin giao thc.

Do trng thi lin kt v knh kh dng thay i lin tc, mt c ch

kch hot cc cp nht trng thi lin kt da trn cc ngng hin c, c th

c thc hin. V d, nhng thay i v kh dng ca cc lin kt c bng


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thng cho trc (v d 48-OC) c th kch hot cc cp nht ch khi nhng

chng thay i mt lng nht nh.

Trong qu trnh xc nh topo mng, thng tin vng ln cn c trao

i thng qua mt giao thc. Sau n s c cng c mc mng to ra

mt bn topo mng. Nhn bit topo t ng khng ch gim chi ph hot

ng ca mng m cn lm tng kh nng biu din chnh xc topo mng.

Nhn bit topo mng c th c xem nh l mt c ch cho php t qun l

mng. Trn quan im ng dng, thng tin topo mng cp nht v t ng

cho php nhng nh hng ca vic chia s ti nguyn n hiu sut ca ng

dng c th d on trc c v cc node v cc lin kt c la chn

thch hp vi nhng kt ni mng ph hp vi nhng yu cu ng dng.

Cc m hnh th hin ti nguyn v qu trnh nhn bit topology qua cc min

WDM i hi cc giao thc nh tuyn lin min, v d nh giao thc BGP vi

nhng m rng cho mng quang. Trong mt mng WDM c kh nng ti cu

hnh, c mt topo ng quang o bn cnh mt topo WDM vt l. Topo

ng quang o l topo IP, do khi cc ng quang c thit lp, topo IP

(cc b nh tuyn mt phng d liu) c th s dng IGP xc nh topo

mng. V d, OSPF s dng bn tin Hello v bn tin m t c s d liu. Topo

vt l WDM c th c xc nh bi giao thc iu khin IP chy trn knh

iu khin WDM.

3.3 nh tuyn IP/WDM

nh tuyn l mt k thut theo lu lng qua mng c th n c

ch t node ngun. Ta s xem xt mt vi vn nh tuyn ca mng

IP/WDM . Ta xem xt vic trin khai OSPF cho cc mng WDM.

3.3.1 Xy dng v duy tr c s thng tin nh tuyn OSPF

Cht lng ca quyt nh nh tuyn lin quan n tnh kh dng,

chnh xc v chi tit ca thng tin nh tuyn. Mt mng IP thng thng s

dng giao thc nh tuyn RIP hay OSPF, OSPF l giao thc nh tuyn da


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trn trng thi lin kt v hi t nhanh hn RIP. OSPF duy tr mt c s trng

thi lin kt, ng b nhng bn sao ca trng thi lin kt, mt c ch

flooding tin cy c pht trin cho OSPF. Hnh 3-2 ch ra c ch flooding

trong trm c 6 node:

Hnh 3-2: C ch flooding OSPF

Node A quan st thy thay i trng thi lin kt bt u flood thay i

trng thi lin kt ny s dng gi tin cp nht trng thi lin kt. Node A gi

LSU (cp nht trng thi lin kt) ti mi node bn cnh n l B,C,F. Trong

hnh 3-2 (b) cc node B,C,F chuyn tip bn tin c flood ny ti cc node

hng xm ca n ngoi tr node m n va nhn bn tin t tc l node A.

Hnh 3-2 (c) ch ra vng tip theo khi node E v D flood LSU. bo li rngLSU n ch c an ton, node nhn s gi mt link state

acknowledgement ti node gi i. Ch rng nu node nhn m nhn c t

node gi cng mt LSU m n gi i, n s khng gi i link state

acknowledgement(d).

A

b c

d

e (a)F

A

b c

d

e (b)F

A

b c

d

e(c)

F

A

b c

d

e(d)

F


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Trong h thng qun l mng WDM ca m hnh chng ln, b qun l

cu hnh v kt ni duy tr c s thng tin nh tuyn. C s d liu ban u

c thng bo qua cc giao din qun l c xc nh trc v sau

c cp nht bi cc thng bo ca NE. tng tnh kh dng ca thng tin

nh tuyn WDM, cc mng WDM c th dng mt c s d liu trng thi

lin kt quang, n c th phn b ti tng chuyn mch. Mt v d ca trin

khai nhng m rng cho IP OSPF flood LSA loi khng trong sut. C s

d liu trng thi lin kt quang c th tch bit khi c s d liu trng thi

lin kt IP tiu chun nhng c th duy tr v ng b bng cch s dng cng

mt c ch flooding.

Nhng m rng OSPF cho mng WDM s c bn ti phn sau

chng ny. Thay cho vic phi tch ri c s thng tin nh tuyn v NMS

cho mng IP v WDM, mt phng php hiu qu hn l thit k mt c s

d liu trng thi lin kt tch hp cho mng IP/WDM .

Trong min nh tuyn IP, cc b nh tuyn BGP duy tr mt bng

nh tuyn BGP bn cnh bng nh tuyn IGP. i vi nh tuyn lin min

quang, cn c mt c s qun l d liu (MIB) ng quang (ligth path) ti

WDM bin bn cnh MIB bc sng. BGP vi phn m rng c th c s

dng cho knh iu khin trao i thng tin v kh dng v kh nng

n ch ca WDM lin min. Nu nh cung cp khc nhau cung cp NE

trong min quang i hi phi ch n tnh lin thng gia cc mng.

3.3.2 Tnh ton ng i v nhng rng buc chuyn mch WDM.

Khi c s d liu nh tuyn c xy dng, vic tnh ton ng i

c th

c tin hnh thng qua mt thut ton nh tuyn. B giao thc IP sdng giao thc tm ng ngn nht (SPF)- hay l tm ng i ti u.

nh tuyn ng v phn b bc sng;

Trong mng WDM c th c ci cc thut ton nh tuyn trong mt

node m c kh nng kt cui ng quang v trang b cho cc node cn li


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ch l mt thut ton tm ng c bn. Cch tip cn ny cng vi vic s

dng MPLS iu khin lu lng, nhng n li khc vi OSPF trong mng

IP ni m tt c cc node chy cng mt thut ton tm ng i. So snh vi

nh tuyn tnh v vic nh tuyn ng v phn b bc sng phi gii quyt

cc ng quang ng v thi gian tn ti ngn v tnh ton ng i trong

thi gian thc. Do tnh phc tp nh tuyn v phn b bc sng c th s

dng cc gii thut da trn kinh nghim gii quyt ng i.

Bo v lightpath:

Mt vn khc lin quan n nh tuyn lightpath WDM l bo v

lightpath. Bn cht knh ca mng WDM i hi mt lightpath d phngtrong trng hp c li hoc c s c vi lightpath chnh. Khi lu lng

gia hai node c th c gi lin tc cho d c s c xy ra. Do mt vn

c bn l cc SRLG trong ng i chnh phi bit c trong khi tnh ton

ng i thay th cng vi tnh kh dng ca ti nguyn trong cc lin kt

thuc SRLG khc.

Cc thut ton nh tuyn ng i d phng nh: Thut ton ng i

tch ri (disjoint). C hai nhm thut ton nh tuyn

ng i tch ri:Cpngn nht ca cc ng i tch ri v ng i tch ri ti a.

Thut ton ng i tch ri ngn nht c kh nng tnh ton node hoc

cc ng kt ni tch ri: Trong thut ton ny (cp node tch ri hay cp

lin kt tch ri), vi mt cp node cho trc, trc tin tm ng i ngn

nht vi s mng cho trc, sau xo b cc lin kt c lin quan n cc

node c ng i ngn nht v cui cng tm ng ngn nht trn s

mng cn li. Vi thut ton ny khi c s c cc lin kt hoc cc node linquan n lightpath chnh khng nh hng n lighpath d phng.

Thut ton ng i tch ri ti a nhm mc ch tm cp ng i

ngn nht m cng tch ri nhau ti a, tc l cp ng i c s node v lin

kt chung nhau l t nht.


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Nhng rng buc chuyn mch WDM:

Vic tnh ton ng i chnh cho mt lightpath trong mt mng

WDM c nhng rng buc v nh tuyn. Rng buc ny thng th

ng l kh dng ca bc sng cn thit cho lightpath cng vi nhng rng buc v

qun l.

Nhng rng buc trong mng WDM cho nh tuyn ng v phn b

bc sng bao gm:

Tnh kh dng ca bc sng, kh nng thay i ca bc sngv bng thng ca si, s lng bc sng trn mt giao din

truyn dn. Loi trng chuyn mch: trong sut hay khng trong sut. Yu cu nh dng tn hiu ca client hoc tc line. Kh nng ghp knh ca cng. Rng buc bin ca nhiu fabric Nhng rng buc v cht lng tn hiu: t s tn hiu trn tp

m, tn sc bc sng.

V nhng giao thc IGP hin ti nh IS-IS v OSPF vic la chn

ng i da trn nhng tnh ton ng i ngn nht, iu khng xem xt

n nhng c tnh lu lng v nhng rng buc kh nng ca mng. Nhng

tin b gn y trong MPLS m ra kh nng mi vt qua mt vi gii

hn ny bng cch cho php ngi dng thit lp cc ng i LSP ring bit

ti cc thit b bin. Tuy nhin t c iu ny IGP phi c chnh

sa nh chng c th phn b thm thng tin cho tnh ton ng i bn

cnh thng tin topo mng. Trong cc mng WDM ni m c nhiu rng buc

v dung lng hn mt vi m rng WDM cho cc giao thc IGP c

thc hin nh b chuyn mch bin c th thit lp cc ng quang thch

hp.


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3.3.3 Hot ng nh tuyn

Mt giao thc nh tuyn trin khai cc c ch phn pht thng tin

nh tuyn trong mng, da trn thng tin nh tuyn ny thut ton tm

ng i xc nh cch m lu lng c dn qua mng. Trong phn ny ta

s xt cc vn hot ng nh tuyn chung.

Routing loops

Mt vn ni bt ca nh tuyn phn b l cc vng lp nh tuyn,

n tn ti do bn cht vic ra quyt nh song song trong mi trng phn tn.

Mt vng lp nh tuyn c th l mt vng lp thng tin hoc vng lp

chuyn tip.Hnh 3-3 ch ra nguyn nhn ca cc vng lp thng tin c hnh

thnh khi thng tin cp nht c ngun gc t thng tin n phn phi trc .

V d trong hnh 3-3 (a) khi cc lin kt AB v BC b down, node A v node C

cho rng cc node khc c mt ng i ti node B, nhng thc t quyt nh

ca chng l da trn thng tin do chnh nhng node ny cung cp. Giao thc

nh tuyn RIP s dng s lng hop ti a n ch l 16 loi tr lp

nh tuyn.

Hnh 3-3: Vng lp nh tuyn

Bng nhtuyn:

B 1hopC 1hopD 1hop

A 1hopD 2hopC 1hop

a b

cd

A

b c

d

(b)F

B 1hopC 1hopD 1hop

B 1hopC 1hopD 1hop

B 1hopC 1hopD 1hop

B 1hopD 1hopA 1hop

(a) Information Loop (b) Forwarding Loop

E

Bng nhtu n:

Bng nhtu n:


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Lp chuyn tip to nn khi lu lng c chuyn tip bi mt b nh

tuyn cui cng li quay tr li router . Hnh 3-3 (b) ch ra mt v d ca

lp chuyn tip gia cc node C,D v E.

Lp nh tuyn c th lin tc hoc tm thi tu theo khong thi gian.

Lp nh tuyn tm thi thng xy ra hn v gy ra t h hng v suy gim

cht lng mng hn lp nh tuyn lin tc. Lp nh tuyn tm thi c th

gy ra nhng h hng v c th gy tc nghn gia cc thnh phn mng. Lp

nh tuyn lin tc c th cn phi shutdown mt phn mng, lm hao ph ti

nguyn mng v c kh nng lm gin on cc dch v hot ng.

Cc li nh tuyn:

nh tuyn trong mt h thng c mc phn tn cao c th b li do

mt vi nguyn nhn:

Cc li nh tuyn do nhng li phn mm iu khin, do hhng phn cng.

Li nh tuyn do tm thi ngng hot ng, c c th gy ra bitc nghn hoc tm thi b mt kt ni hoc do cu hnh kt ni

thay i. Khng th n c ch do qa nhiu chng

n nh ca nh tuyn

L mc thng xuyn ca vic thay i ng i v mc n nh

ca chng. C hai nh ngha v n nh nh tuyn l s ph bin v tnh

nht qun.

S ph bin: n nh nh tuyn c th nh ngha di dng s ph

bin, l xc xut ca vic quan st mt ng i cho trong mt khongkhung thi gian cho trc. Khi quan st mt ng i, s ph bin ch ra rng

ta s quan st li c ng i trong tng lai. S ph bin cao l mi

trng nh tuyn n nh.


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Tnh nht qun: n nh nh tuyn c th c nh ngha di

dng tnh nht qun, l khung thi gian m mt ng i cho trc tip tc

tn ti cho n khi n thay i. Mc nht qun cao hn c ngha l mi

trng nh tuyn n nh lu hn.

S ph bin v tnh n nh c th kt hp vi nhau m t n

nh nh tuyn. Cc mc cao ca tnh nht qun v s ph bin th hin

mng rt n nh. Mc ph bin cao nhng mc nht qun thp mng s

khng n nh, c th c lp nh tuyn. Mc ph bin v nht qun u

thp th hin mt mng rt khng n nh. Mt mi trng nh tuyn khng

n nh c kh nng gy ra nhng vn sau;

Nhng c tnh ca cc ng i mng khng th d on c Kinh nghim v hiu qu ca vic hc da trn nhng o lng

trc l khng tin cy.

3.4 Bo hiu trong mng IP/WDM

Ti lp vt l, bo hiu c ngha l vic truyn tn hiu quang qua si

quang. Ti lp iu khin mng, bo hiu lin quan n mt lot qu trnh

phn b hon thnh cc vic nh

thit lp knh qua mngTrong phn ny s dng giao thc bo hiu RSVP (Resource

Reservation Protocol) v phn m rng quang minh ho qu trnh bo hiu v

hot ng trong cc mng IP/WDM

3.4.1 Khi nim RSVP

RSVP l mt giao thc bo hiu IP cho php cc ng dng IP t c

cht lng dch v nht nh cho cc lung d liu trong cc mng IP. RSVP

dnh trc cc ti nguyn vi cht lng dch v yu cu thng qua ch tiulung, n m bo lin mng x l lu lng ng dng.

Ch tiu k thut lung bao gm yu cu v cht lng dch v (RSpec),

m t v lung lu lng (TSpec), v cp dch v ca mt ng dng. Thng

qua vic dnh trc, cc tham s nht nh trong lp trnh v b phn loi


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c thit lp cc gi tr c th cc lung ng dng c cung cp vi cc

dch v tng ng khi chng n.

C nhiu kiu dnh trc khc nhau da trn tnh nng cung cp bi

nh qun l ti nguyn (RSVP daemon). Vic dnh trc c th l ring bit

trong mi s dnh trc ca mt phin t pha gi c x l ring r,

hoc l chia s trong tt c cc s dnh trc c x l nh l mt s

dnh trc (v chng c bit n nh l khng can thip ln nhau). Mt s

dnh trc ring bit cng c th nh r vi mt phm vi r rng thng qua

b lc c nh, v d nhbng cch ch ra r rng mt ngi gi.

Khi ng i nh tuyn c xc nh bi mt giao thc nh tuyn

hoc mt ng dng iu khin lu lng m rng, RSVP daemon ch (host)

bt u mt phin v gi mt bn tin RSVP theo ng i nh tuyn n

ch . Khi bn tin ng i n ch, pha thu bt u dnh trc ti nguyn

v gi bn tin yu cu dnh trc dc theo ng i nh tuyn dnh trc

n pha gi. Trong qu trnh dnh trc, mi node bao gm b thu v pht c

nhim v la chn mc ca ring n v ti nguyn dnh trc , mt qu

trnh c gi l iu khin admission, xc nh liu n c th cung cp

cht lng dch v theo yu cu. Nu iu khin admission khng thnh cng,

mt bn tin li c gi n pha ngun. RSVP nh ngha 4 nhm bn tin:

Path messages, bao gm trng thi ca ng i trong mi node,c gi i tng chng theo ng nh tuyn t ngun n ch.

Reservation request messages, thng tin chi tit v dnh trc,c gi i tng chng theo ng nh tuyn t ngun n

ch. Tear-down messages, c s dng loi b ng i v dnh

trc m khng cn phi i cho thi gian cleanup ht hn. C

hai loi bn tin tear-down l: Cc bn tin path tear-down; Cc bn


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tin tear-down yu cu dnh trc.B pht, b thu hoc bt c mt

b nh tuyn no c th khi to cc bn tin tear-down.

Error and confirmation messages, bao gm: Cc bn tin ling i c dng thng bo cc li cho cc bn tin ng

i, v c gi i tng chng dc theo ng i v pha host

ngun. Cc bn tin li yu cu dnh trc c dng thng

bo cc li cho cc bn tin yu cu dnh trc, v c gi i

tng chng dc theo ng i v pha ch; Cc bn tin xc nhn

yu cu dnh trc c dng xc nhn bn tin yu cu dnh

tr

c, v

c gi tng chng dc theo

ng i v pha b thu.V RSVP c s dng cho cc lung ng dng, nn n l n hng.

Mt ng i hai chiu phi c thit lp bng cch thc hin bo hiu

RSVP hai ln, i chiu v tr ca pha thu v pha pht. Cc

Ip Tren Quang

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