Đồ án chuyển mạch nhãn đa giao thức MPLS

8/2/2019 n chuyn mch nhn a giao thc MPLS

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Mc lc

Mc lc

Thut ng v vit tt ............................................................iv

...........................................................................

Trn Th Hng Tr - D2001VT i


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Danh mc hnh

Danh mc Hnh

Thut ng v vit tt ............................................................ivHp nht nhn ...................................................................................15

S duy tr nhn ................................................................................16iu khin nhn ................................................................................16

Trn Th Hng Tr - D2001VT iii


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Thut ng vit tt

Thut ng v vit ttAAL5 ATM Adaptation Layer 5 Lp thch ng ATM 5API Application Programming

InterfaceGiao Din chng trnh ngDng

ASN.1 Abstract Syntax NotationNumber One

Chuyn mch IP theo phngphp tng hp tuyn

ARP Addresss Resolution Protocol Giao thc phn tch ach

AS Autonomous System H t qunATM Asynchronous Transfer Mode Phng thc truyn ti khng

ng bBBRAS BroadBand Remote Access

ServerMy ch truy nhp t xa bngrng

BCF Bearer Contrrol Function Khi chc nng iu khin

ti tinBGP Border Gateway Protocol Giao thc nh tuyn cngmin.

BOF Board Of a Founders Cuc hp tr b WG-IETFCOS Class of Service Lp dch vCPE Customer Premise

EquipmentThit b pha khch hng

CR Cell Router B nh tuyn t boCSPF Constrained Shortest Path

FirstGiao thc nh tuyn tmng ngn nht.

DNS Domain Name System H thng tn min

DLCI Data Link ConnectionIdentifier Nhn dng kt ni lp lin ktd liuDS Differentiated Service Cc dch v khc nhauECR Egress Cell Router Thit b nh tuyn t bo

li raEGP Edge Gateway Protocol Giao thc nh tuyn cng

binEMS Element Management

SystemH thng qun l phn t

FEC Forwarding EquivalenceClass

Nhm chuyn tip tng -ng

FIB Forwarding Infomation Base C s d liu chuyn tiptrong b nh tuyn

FR Frame Relay Chuyn dch khungFTN FEC - to - NHLFE Sp xp FEC vo NHLFEIBM International Bussiness

MachineCng ty IBM

ICMP Internet Control MessageProtocol

Giao thc bn tin iu khinInternet

ICR Ingress Cell Router Thit b nh tuyn t boli vo

IETF International EngineeringTask Force T chc tiu chun k thutquc t cho Internet

Trn Th Hng Tr - D2001VT iv


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Thut ng vit tt

IGP Interior Gateway Protocol Giao thc nh tuyn trongmin

IN Intelligent Network Mng thng minhINTSERV Integrated services Dch v tch hpIP Internet Protocol Giao thc nh tuyn

InternetIPv4 IP version 4 IP phin bn 4.0ISC International Softswitch

ConsortiumT chc chuyn mch mmquc t.

ISDN Intergrated Service DigitalNetwork

Mng s lin kt a dch v

ISIS Intermediate System Intermediate System

Giao thc nh tuyn IS-IS

IT Information Technology K thut thng tinLAN Local Area Network Mng cc bLC-ATM Label Controlled ATM

InterfaceGiao din ATM iu khinbi nhn

LDP Label Distribution Protocol Giao thc phn phi nhnLFIB Label Forwarding

Information BaseC s d liu chuyn tipnhn

LIB Label Information Base Bng thng tin nhn trong bnh tuyn

L2TP Layer 2 tunnel protocol Giao thc ng hm lp 2LMP Link Management Protocol Giao thc qun l knhLPF Logical Port Fuction Khi chc nng cng logicLSP Label Switched Path Tuyn chuyn mch nhn

LSR Label Switching Router B nh tuyn chuyn mchnhnMAC Media Access Controller Thit b iu khin truy

nhp mc phng tin truynthng

MG Media Gateway Cng chuyn i phngtin

MGC Media Gateway Controller Thit b iu khin MGMIB Management Information

BaseC s d liu thng tin qunl

MPLS MultiProtocol Label Switching Chuyn mch nhn a giao

thcMPOA MPLS over ATM MPLS trn ATMMSF MultiService Switch Forum Din n chuyn mch a

dch vNGN Next Generation Network Mng th h sauNHLFE NextHop Label Forwarding

EntryPhng thc gi chuyn tipgi tin dn nhn

NHRP Next Hop Resolution Protocol Giao thc phn tch ach nt tip theo

NLPID Network Layer ProtocolIdentifier

Nhn dng giao thc lp mng

NNI Network Network Interface Giao din mng - mngNMS Network Management H thng qun l mng

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Thut ng vit tt

systemOID Object Identifier Nhn dng i tngOOD Object- Oriented Design Thit k i tng nh hngOPSF Open Shortest Path First Giao thc nh tuyn OSPFOSI Open Systems

Interconnection

Kt ni cc h thng m

OSS Operation Support system H thng h tr vn hnhPDU Protocol Data Unit n v d liu giao thcPSTN Public switch telephone

NetworkMng chuyn mch thoi cngcng

PVC Permanent Virtual Circuit Knh o c nhQOS Quality Of Service Cht lng dch vRFC Request for Comment Cc ti liu v tiu chun IP

do IETF a raRIP Realtime Internet Protocol Giao thc bo hiu IP thi

gian thcRSVP Resource Reservation

ProtocolGiao thc ginh trc tinguyn (h tr QoS)

SHA1 US Secure Hash Algorithm 1SIN Ship- in-the-NightSLA Service Level Agreement Tho thun mc dch v

gia nh cung cp v khchng

SNAP Service Node Access Point im truy nhp nt dch vSNI Signalling Network Interface Giao din mng bo hiuSNMP Simple Network

Management Protocol

Giao thc qun l mng n

ginSONET Synchronous OpticalNetwork

Mng truyn dn quangng b

SP Service Provider Nh cung cp dch vSPF Shortest Path First Giao thc nh tuyn ng

ngn nhtSVC Switched Virtual Circuit Knh o chuyn mchTCP Transport Control Protocol Giao thc iu khin truyn

tiTDP Tag Distribution Protocol Giao thc phn phi thTE Terminal Equipment Thit b u cui

TGW Trunking Gateway Cng trung kTLV Type-Length- Value Gi tr chiu di tuyn (s

nt)TMN Telecommunication

Mngement NetworkMng qun l thng tin

TOM TelecommunicationsOperations MAP

Hot ng thng tin MAP

TOS Type of Service Cc kiu dch vUSM User based security Model Kiu bo mt c s ngi s

dngUDP User Data Protocol Giao thc d liu ngi s

dngVC Virtual Circuit Knh o

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Thut ng vit tt

VCI Virtual Circuit Identifier Trng nhn dng knh otrong t bo

VNS Virtual Network Service Dch v mng oVPI Virtual Path Identifier Nhn dng ng oVPN Virtual Private Network Mng ring o

VPNID Virtual Private NetworkIdentifier Nhn dng mng ring o

VR Virtual Router B nh tuyn oVSC Virtual Switched Controller Khi iu khin chuyn

mch oVSCF Virtual Switched Control

FuctionKhi chc nng iu khinchuyn mch o

VSF Virtual Switched Fuction Khi chc nng chuyn mcho

WAN Wide Area Network Mng din rngWDM Wave Division Multiplexing Ghp knh phn chia theo b-

c sngWFQ Weighted Factor Queque Hng i theo trng s

Trn Th Hng Tr - D2001VT vii


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Li ni u

Li ni u

p ng nhu cu pht trin bng thng khng ngng ca

ngi s dng, nh cung cp dch v (ISP) cn c thit b nh

tuyn v chuyn mch tc cao.

Nhu cu v mt phng thc chuyn tip n gin m cc

c tnh qun l lu lng v cht lng chuyn mch truyn thng -

c kt hp vi chuyn tip thng minh ca mt b nh tuyn l rt

r rng. Tt c cc nhu cu c th c p ng bi chuyn

mch nhn a giao thc, n khng b hn ch bi mi giao thc lp 2

v lp 3. C th l, MPLS c mt vi ng dng v c th c m rngqua cc phn on a sn phm (nh mt b nh tuyn MPLS,

mt b nh tuyn/chuyn mch dch v IP, mt chuyn mch

Ethernet quang cng nh chuyn mch quang). MPLS l mt gii php

quan trng trong vic nh tuyn, chuyn mch v chuyn tip

cc gi thng qua mng th h sau p ng cc yu cu dch

v ca ngi s dng mng.

Bi ton qun l mng lun c t ra vi bt k giai on noca qu trnh xy dng v pht trin h thng, SNMP l giao thc

qun tr mng n gin c s dng ph bin nht trn mng IP.

Trong qu trnh hi t cc c trn nn mng IP, giao thc qun l

mng n gin th hin tt cc yu cu c bn. Tuy nhin, vic

ci thin c s thng tin qun l MIB l mt xut tip cn ti ph-

ng php qun l v x l phn tn cc thng tin qun l mng hiu

qu.

Lun vn tt nghip ca em trnh by nhng kin thc cbn v cng ngh chuyn mch nhn, vn qun l mng vinthng v bi ton ci thin cng nh thc t trin khai cc ng dnglin quan ti c s thng tin qun l MIB trong mng MPLS . Do thigian v trnh c hn, lun vn tt nghip ca em kh trnh khinhng sai st, rt mong s ch bo ca cc thy c gio.

Trn Th Hng Tr - D2001VT vii


8/84

Li ni u

H Ni ngy 25thng 10 nm 2006

Sinh vinthc hin

Trn ThHng Tr

Trn Th Hng Tr - D2001VT viii


9/84

n tt nghip i hc Chng 1: Tng quancng ngh MPLS

Chng 1:

TNG quaN V Cng ngh chuyn mch nhn agiao thc MPLS

1.1. Khi nim c bn v chuyn mch nhn

Khi nim chuyn mch nhn tng i n gin. hnh dungvn ny chng ta xem xt mt qu trnh chuyn th in t t

h thng my tnh gi n h thng my tnh nhn. Trong mng

internet truyn thng (khng s dng chuyn mch nhn) qu trnh

chuyn th in t ging ht qu trnh chuyn th thng thng. Cc

a ch ch c truyn qua cc thc th tr (cc b nhtuyn). a ch ch s l yu t xc nh con ng m gi

tin chuyn qua cc b nh tuyn. Trong chuyn mch nhn, thay

v s dng a ch ch quyt nh nh tuyn, mt

nhn c gn vi gi tin v c dt trong tiu gi tin vi mc

ch thay th cho a ch v nhn c s dng chuyn lu lng

cc gi tin ti ch.

Mc tiu ca chuyn mch nhn a ra nhm ci thin hiu nng

chuyn tip gi tin ca cc b nh tuyn li qua vic s dng ccchc nng gn v phn phi nhn gn vi cc dch v nh tuyn

lp mng khc nhau. Thm vo l lc phn phi nhn hon

ton c lp vi qu trnh chuyn mch.

Trc ht ta xem xt mt s l do c bn hin nay ang c

quan tm vi cng ngh mng ni chung v chuyn mch nhn: tc

v tr, kh nng ca h thng, tnh n gin, ti nguyn

mng, iu khin nh tuyn.

Tc v tr

Theo truyn thng chuyn tip gi tin da trn phn mm rt

chm trong qu trnh x l ti lu lng ln trong internet v intranet,

tr ch yu trong qu trnh ny l qu trnh x l nh tuyn

tm ra thch hp cho cc gi tin u vo. Mc d c nhiu ci

thin trong vic tm kim bng nh tuyn nh k thut tm kim

nhanh trong bng nh tuyn, nhng ti lu lng trong bng nh

tuyn lun ln hn kh nng x l, v kt qu c th mt lu lng,mt u ni v gim hiu nng ca ton mng (mng IP). Chuyn

Trn Th Hng Tr - D2001VT 1


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mch nhn a ra cch nhn nhn khc vi chuyn tip gi tin IP

thng thng, s cung cp gii php c hiu qu gii quyt vn

trn. Chuyn mch nhn thc hin qu trnh gn nhn cho gi tin

u vo v s dng nhn truy nhp vo bng chuyn tip ti b

nh tuyn nh mt ch s ca bng. Qu trnh truy nhp ny ch

yu cu duy nht cho mt ln truy nhp ti bng thay v hng ngn

qu trnh tm kim c thc hin trong bng nh tuyn truyn

thng. Kt qu l cc hot ng ny hiu qu hn v v vy lu lng

ngi s dng trong gi tin c gi qua mng nhanh hn, gim

tr v thi gian p ng tt hn cho cc chuyn giao thng tin gia

cc ngi s dng.

Mng my tnh lun tn ti cc hiu ng tr, khi cc gi tinchuyn qua rt nhiu nt v nhiu chng khc nhau ti ch

n to ra cc hiu ng tr v bin ng tr. S tch tr trn cc

cung on s to ra tr tng th gia cc u cui. Ti mi nt

mng a ch ch trong gi tin c xc minh v so snh vi cc

a ch ch c kh nng chuyn tip trong bng nh tuyn

tm ra ng ra. Cc gi tin chuyn qua cc nt mng to ra tr

v bin ng tr khc nhau, tu thuc vo kh nng x l ca b

nh tuyn cng nh lu lng ca lung tin s nh hng trc tip ntr ca ngi dng u cui. Mt ln na, c ch hot ng ca

chuyn mch nhn vi kh nng chuyn tip gi tin nhanh l gii

php gii quyt vn ny.

Kh nng ca h thng

Tc l mt kha cnh quan trng ca chuyn mch nhn v

tng qu trnh x l lu lng ngi dng trn mng internet l vn

rt quan trng. Nhng cc dch v tc cao khng phi l tt cnhng g m chuyn mch nhn cung cp. Chuyn mch nhn cn

c th cung cp mm do cc tnh nng khc nhau p ng cc

nhu cu ca ngi dng internet. Thay v hng lot cc a ch IP

(tng ln rt nhanh tng ngy) m b nh tuyn cn phi x l

th chuyn mch nhn cho php cc a ch ny gn vi mt hoc

vi nhn. tip cn ny lm gim kch thc bng a ch v cho

php b dnh tuyn h tr nhiu ngi s dng hn.

Tnh n gin



11/84


Mt kha cnh khc ca chuyn mch nhn l s n gin

trong cc giao thc chuyn tip gi tin (hoc mt tp cc giao

thc), v nguyn tc rt n gin:chuyn tip gi tin da trn

nhn ca n.Tuy nhin, cn c k thut iu khin cho qu trnh

lin kt nhn v m bo tnh tng quan gia cc nhn vi lung lu

lng ngi s dng, cc k thut ny i khi kh phc tp nhng chng

khng nh hng n hiu sut ca dng lu lng ngi dng. Sau khi

gn nhn vo dng lu lng ngi dng th hot ng chuyn mch

nhn c th nhng trong phn mm, trong cc mch tch hp c

bit (ASIC) hoc trong b x l c bit.

Ti nguyn s dng

Cc k thut iu khin thit lp nhn khng chim dngti nguyn ca mng, cc c ch thit lp ng chuyn mch nhn

cho lu lng ngi s dng mt cch n gin l tiu ch thit k cc

ng chuyn mch nhn.

iu khin nh tuyn

nh tuyn trong mng Internet c thc hin vi cc a ch

IP (trong mng LAN l cc a ch MAC). Tt nhin, c rt nhiu

thng tin c ly ra t gi IP thc hin qu trnh nh tuyn

ny, v d nh: Trng kiu dch v IP (TOS), ch s cng...l mtphn quyt nh ca chuyn tip gi tin. Nhng nh tuyn theo

ch l phng php thng thng nht hin ang c s dng.

nh tuyn theo a ch ch khng phi l phng php

lun em li hiu qu. Cc vn lp vng trn mng cng nh s

khc nhau v kin trc mng s l tr ngi trn mt bng iu

khin chuyn tip gi tin i vi phng php ny. Mt vn t

ra na l cc nh cung cp thit b (b nh tuyn, cu). Trinkhai phng php nh tuyn da theo a ch ch theo cch

ring ca h: mt s thit b cho php nh qun tr mng chia s lu

lng, trong khi mt s khc s dng cc trng chc nng TOS, ch s

cng...

Chuyn mch nhn cho php cc b nh tuyn chn tuyn

u ra tng minh theo nhn, nh vy c ch ny cho cung cp mt

phng thc truyn ti lu lng qua cc nt v lin kt ph hp vi lu l-

ng truyn ti, cng nh l t ra cc lp lu lng bao gm cc dch v



12/84


khc nhau (da trn yu cu QOS) trn . Chuyn mch nhn l gii

php tt hng lu lng qua mt ng dn, m khng nht thit

phi nhn ton b thng tin t giao thc nh tuyn IP ng da

trn a ch ch.

nh tuyn da trn IP (PRB) thng gn vi cc giao thc

chuyn mch nhn, nh FR, ATM hoc MPLS. Phng php ny s dng

cc trng chc nng trong tiu gi tin IP nh: trng TOS, ch s

cng, nhn dng giao thc IP hoc kch thc ca gi tin. Cc trng

chc nng ny cho php mng phn lp dch v thnh cc kiu lu l-

ng v thng c thc hin ti nt u vo mng(thit b g mng).

Cc b nh tuyn trn lp li c th s dng cc bt ti thit

b g quyt nh x l lung lu lng n, qu trnh x l nyc th s dng cc kiu hng i khc nhau v cc phng php xp

hng khc nhau. nh tuyn da trn IP cng cho php nh qun l

mng thc hin phng php nh tuyn rng buc. Cc chnh sch

da trn IP cho php b nh tuyn:

- t cc gi tr u tin vo trong tiu gi tin IP.

- Thit lp bc k tip cho gi tin IP.

- Thit lp giao din ra cho gi tin.

- Thit lp bc k tip cho gi tin khi khng tn ti hng trongbng nh tuyn.

Chuyn mch nhn khc vi phng php chuyn mch khc

ch n l k thut iu khin giao thc chuyn mch IP theo kiu

topo. Mt khc s tn ti ca mt a ch mng ch s xc nh

qu trnh cp nht trong bng nh tuyn ra mt ng dn

chuyn mch hng ti ch. N cng khi qut c cu chuyn tip

v trao i nhn, phng php ny khng ch thch hp vi cc mngln nh ATM, chuyn mch khung, PPP, v n c th thch hp vi bt

k phng php ng gi no.

1.2. Tng quan v cng ngh chuyn mch nhna giao thc

1.2.1. Cc c im c bn ca cng ngh MPLS



13/84


MPLS l mt cng ngh tch hp tt nht cc kh nng hin ti

phn pht gi tin t ngun ti ch qua mng Internet. C th

nh ngha MPLS l mt tp cc cng ngh m da vo chun

Internet m kt hp chuyn mch lp 2 v nh tuyn lp 3

chuyn tip gi tin bng cch s dng cc nhn ngn c chiu di

c nh.

Bng cch s dng cc giao thc iu khin v nh tuyn

Internet MPLS cung cp chuyn mch hng kt ni o qua cc tuyn

Internet bng cch h tr cc nhn v trao i nhn. MPLS bao gm

vic thc hin cc ng chuyn mch nhn LSP, n cng cung cp

cc th tc v cc giao thc cn thit phn phi cc nhn gia

cc chuyn mch v cc b nh tuyn .Nghin cu MPLS ang c thc hin di s bo tr ca nhm

lm vic MPLS trong IETF. MPLS vn l mt s pht trin tng i

mi, n mi ch c tiu chun ho theo Internet vo u nm 2001.

S dng MPLS trao i khe thi gian TDM, chuyn mch

khng gian v cc bc sng quang l nhng pht trin mi nht. Cc

n lc ny c gi l GMPLS (Generalized MPLS ).

Nhm lm vic MPLS a ra danh sch vi 8 bc yu cu xc

nh MPLS l:1. MPLS phi lm vic vi hu ht cc cng ngh lin kt d

liu.

2. MPLS phi thch ng vi cc giao thc nh tuyn lp

mng v cc cng ngh Internet c lin quan khc.

3. MPLS cn hot ng mt cch c lp vi cc giao thc

nh tuyn.

4. MPLS phi h tr mi kh nng chuyn tip ca bt knhn cho trc no.

5. MPLS phi h tr vn hnh qun l v bo dng (OA&M).

6. MPLS cn xc nh v ngn chn chuyn tip vng.

7. MPLS cn hot ng trong mng phn cp

8. MPLS phi c tnh k tha.

Tm yu cu ny chnh l cc n lc pht trin cn tp trung. Lin

quan ti cc yu cu ny, nhm lm vic cng a ra 8 mc tiu

chnh m MPLS cn t c:



14/84


1. Ch r cc giao thc c tiu chun ho nhm duy

tr v phn phi nhn h tr nh tuyn da vo

ch unicast m vic chuyn tip c thc hin bng

cch trao i nhn. (nh tuyn unicast ch ra mt cch

chnh xc mt giao din; nh tuyn da vo ch ng

l nh tuyn da vo a ch ch cui cng ca gi

tin).


tr v phn phi nhn h tr nh tuyn da vo

ch multicast m vic chuyn tip c thc hin bng

cch trao i nhn. (nh tuyn mulicast ch ra hn mt

giao din u ra. Nhim v tch hp cc k thutmulticast trong MPLS vn ang tip tc nghin cu v

pht trin.


tr v phn phi nhn h tr phn cp nh tuyn

m vic chuyn tip c thc hin bng cch trao i

nhn , phn cp nh tuyn ngha l hiu bit v topo

mng trong h thng t tr.

4. Ch r cc giao thc c tiu chun ho nhm duytr v phn phi nhn h tr cc ng ring da vo

trao i nhn. Cc ng ny c th khc so vi cc ng

c tnh ton trong nh tuyn IP thng thng ( nh

tuyn trong IP da vo chuyn tip theo a ch ch ).

Cc ng ring rt quan trng trong cc ng dng TE.

5. Ch ra cc th tc c tiu chun ho mang

thng tin v nhn qua cc cng ngh lp 2.6. Ch ra mt phng php tiu chun nhm hot ng

cng vi ATM mt phng iu khin v mt phng ng-

i dng.

7. Phi h tr cho cc cng ngh QoS ( nh l giao thc

RSVP) (QoS l mt trong nhng ng dng quan trng nht

ca MPLS, MPLS QoS s c th mang li nhiu li ch cho

mng th h sau).



15/84


8. Ch ra cc giao thc tiu chun cho php cc host

s dng MPLS.

1.2.2. Cch thc hot ng ca MPLS

MPLS c th c xem nh l mt tp cc cng ngh hot ng

vi nhau phn pht gi tin t ngun ti ch mt cch hiu qu

v c th iu khin c. N s dng cc ng chuyn mch nhn

LSP chuyn tip lp 2 m c thit lp bo hiu bi cc

giao thc nh tuyn lp 3.

c c lp trn

lachn cng ra

nhn gi uvo

cc cng uvo

pht gi u ra

c c cng u ra

duy trtuynmt phngiu khin

mt phngchuyn tip

nh tuyn

chuynmch

chuyn tip

Hnh 1.1: M hnh chung v chuyn tip v chuyn mchti b nh tuyn

Bi v cc khi nim chuyn tip, chuyn mch v nh

tuyn l nhng vn quan trng hiu MPLS hot ng nh

th no do vy ta xem xt cc vn ny trong b nh tuyn.

Mt thit b nh tuyn chuyn mt gi tin t ngun ti ch bng

cch thu hoc nhn, chuyn mch v sau chuyn tip n ti mt

thit b mng khc cho ti khi n ti ch cui cng. Hnh 1.1 trn

y m t m hnh chung v chuyn tip v chuyn mch ti b

nh tuyn.

Mt bng iu khin qun l mt tp cc tuyn ng m mt

gi c th s dng, trong m hnh ny mt gi i vo thit b

mng qua giao din u vo, c x l bi mt thit b m n ch

x l thng tin v gi a ra quyt nh logic. Quyt nh

logic ny c thng tin c cung cp t mt bng iu khin cha

cc tuyn, cho cc thng tin v gi c cp nht ti thit b khc



16/84


chuyn tip gi thng qua giao din u ra ti ch ca

gi tin .

y l m hnh n gin nht trong cc cng ngh mng, nhng

n l s bt u cho cc vn lin quan ti MPLS c thc hin

nh th no. Cc cng ngh MPLS a ra m hnh mi cho vic nh

tuyn, chuyn mch v chuyn tip chuyn cc gi tin trong

mng Internet.

Mt m hnh khc thng gp m t lung cc gi tin gia cc

thit b mng (v d nh l cc b nh tuyn) c trnh by trong

hnh 1.2 di y.

- ng iukhin

- ng chuyn

tip

phn mm

phn cng

- ng iukhin

- ng chuyn

tip

phn mm

phn cng

- ng nhanh

(dliu)

- ng chm(iu khin)

router A router B

data data

Hnh 1.2: M hnh lung gi tin gia hai thit b

mng

Lu lng trong mng c th c hiu theo hai cch: Lu lng iu

khin bao gm cc thng tin v qun l v nh tuyn v Lu lng

d liu. Lu lng d liu th i theo ng nhanh v c x l bi

cc thit b mng. Trong hu ht cc thit b mng hin i, ngnhanh c thc hin bi phn cng. Bt c thit b mng no nhn

mt gi tin khi x l tiu ca gi, thng tin v gi c gi ln -

ng iu khin x l. Cc gi iu khin bao gm cc thng

tin yu cu cho vic nh tuyn gi, bt c mt gi no khc c th

cha thng tin iu khin, cc gi d liu u tin vv.. th c x l

chm bi v chng cn c kim tra bi phn mm. V l do ny

ng x l ny thng c gi l ng chm.



17/84


M hnh ny rt quan trng hiu MPLS hot ng nh th no

bi v n ch ra ng iu khin v ng chuyn tip l ring

bit. Kh nng ca MPLS phn bit cc chc nng quan trng

ny to ra mt phng php mi lm thay i phng thc

truyn cc gi d liu qua mng Internet.

MPLS ch yu lm vic vi cc giao thc lp 2 v lp 3, v cng

hot ng trong nhiu kiu thit b mng khc.

Cng ngh lp 2.5 l mt cch nhn v MPLS. Hnh 1.3 trnh

by MPLS c xem nh l mt lp chn m t t n vo gia lp

mng v lp lin kt d liu.

l p 4-7( l p truyn ti, phin, trnh din, ng dng)

l p 3(l p mng)

l p 2 (lin kt dliu)

l p 1 (l p vt l)

l p 2.5 (MPLS)

Hnh 1.3: Lp chn MPLS

M hnh ny ban u xut hin nh l mt m hnh khngng nht vi OSI, m hnh ny ch ra rng MPLS khng phi l

mt lp mi ring, m n l mt phn o ca mt phng iu khin

di lp mng vi mt phng chuyn tip nh ca lp lin kt

d liu. MPLS khng phi l mt giao thc tng mng mi bi v n

khng c kh nng t nh tuyn hoc c s a ch, m yu

cu phi c trong giao thc lp 3. MPLS s dng cc giao thc nh

tuyn v cch nh a ch ca IP ( vi s iu chnh v m rng

cn thit) MPLS cng khng phi l mt giao thc tng lin kt d

liu bi v n c thit k hot ng trong nhiu cng ngh

lin kt d liu ph bin m cung cp yu cu chc nng v a

ch lp 2.

1.2.3. Cc thut ng trong MPLS

B nh tuyn chuyn mch nhn v b nh tuyn bin

nhn(LSR v LER)



18/84


Cc thit b tham gia trong k thut giao thc MPLS c th c

phn loi thnh cc b nh tuyn bin nhn ( LER) v cc b nh

tuyn chuyn mch nhn (LSR).

Mt LSR l 1 thit b nh tuyn tc cao trong li ca

1 mng MPLS, n tham gia trong vic thit lp cc ng

dn chuyn mch nhn (LSP) bng vic s dng giao thc

bo hiu nhn thch ng v chuyn mch tc cao lu lng

s liu da trn cc ng dn c thit lp.

Mt LER l 1 thit b hot ng ti bin (cnh ) ca mng

truy nhp v mng MPLS. Cc LER h tr a cng c kt

ni ti cc mng khng ging nhau ( chng hn FR, ATM v

Ethernet ) v chuyn tip lu lng ny vo mng MPLS saukhi thit lp LSP, bng vic s dng cc giao thc bo hiu

nhn ti li vo v phn b lu lng tr li mng truy nhp ti

li ra. LER ng vai tr quan trng trong vic ch nh v

hu b nhn, khi lng vo trong hay i ra khi mng MPLS.

Lp tng ng chuyn tip (FEC)

FEC l mt s biu din ca nhm cc gi, cc nhm ny chia

x cng yu cu trong s vn chuyn ca chng. Tt c cc gi trong

mt nhm nh vy c cung cp cng cch chn ng ti ch. Ngc

li vi chuyn tip IP truyn thng, trong MPLS vic gn mt gi c

th vo mt FEC c th c thc hin ch mt ln khi cc gi vo

trong mng. Cc FEC da trn cc yu cu dch v i vi mt tp

cc gi cho trc hay n gin l i vi mt a ch cho trc

(address prefix). Mi LSR xy dng mt bng xc nh xem

mt gi phi c chuyn tip nh th no. Bng ny c gi l mt

bng thng tin nhn c bn (LIB: Label Information Base), n l thp cc rng buc FEC vi nhn (FEC-to-label).

Tiu MPLS

MPLS nh ngha mt tiu c di 32 bit v c to nn

ti LSR vo. N phi c t ngay sau tiu lp 2 bt k v trc

mt tiu lp 3. y l IP v c s dng bi ingress LSR (LSR

vo) xc nh mt FEC, lp ny s c xt li trong vn to

nhn. Sau cc nhn c x l bi LSR transit (LSR chuyn tip).



19/84


Khun dng v tiu MPLS c ch ra trong hnh1.4 . N bao

gm cc trng sau:

Nhn: Gi tr nhn 20 bits, gi tr ny cha nhn MPLS.

Exp: thc nghim s dng 3 bits.

S : bit ngn xp,1 bit, s dng sp xp a nhn.

TTL: Thi gian sng, 8 bit, t ra mt gii hn m cc gi MPLS

c th i qua. iu ny l cn thit bi v trng TTL IP khng

c kim tra bi cc transit LSR (LSR chuyn tip).

Hnh 1.4: nh dng cu trc nhn

Trn Th Hng Tr - D2001VT

Ti Tiu IPmMPLS

Tiu lp 2

Nhn (20) COS(3)S (1)

TTL (8)

11


20/84


Ngn xp nhn

Chuyn mch nhn c thit k co dn cc mng ln vMPLS h tr chuyn mch nhn vi cc hot ng phn cp, hot

ng phn cp ny da trn kh nng ca MPLS c th mang

nhiu hn mt nhn trong gi. Ngn xp nhn cho php thit k cc

LSR trao i thng tin vi nhau v hnh ng ny ging nh vic to

ng vin node to ra mt min mng rng ln v cc LSR khc.

C th ni li rng cc LSR khc ny l node bn trong (transit node)

mt min v khng lin quan n ng vin node (vi cu to

router lin vng) v cc nhn c kt hp trong cc router ny.

S x l mt gi nhn c hon thnh c lp vi tng mc ca

s phn cp. l cc mc nhn th khng c LSR kim tra. gi hot ng n, cc chng trnh x l thng xuyn da trn

nh nhn m khng cn quan tm n nhn trn n lc trc,

hoc di n ti thi im hin ti.

Kt hp lung FEC

Cch thc cc lu lng o n cc FEC ti ra mt FEC ring

bit cho mi a ch prefix. Phng php tip cn ny c kt qu

trong vic thit lp cc FEC, cc lp ny c nh tuyn ging nhauti node ra, vic hon i nhn c th ch c s dng chuyn

lu lng ti node k tip. Trong tnh hung ny trong min MPLS, cc

FEC ring r thc hin th s khng em li hiu qu tt. Trong quan

nim ca MPLS, kt hp cc FEC ny to ra mt FEC c trng cho

tt c l em li hiu qu nht. Trong tnh hung ny c hai la

chn:

- Lin kt mt nhn ring bit ti mt min FEC.

- Lin kt mt nhn ti mt min, ng dng nhn kt hp vi tt

c lu lng trong min.

Th tc lin kt mt nhn n ti mt min kt hp cc FEC,

min ny chnh l mt FEC (trong min MPLS ging nhau) v ng

dng cc nhn cho tt c cc lu lng trong min kt hp. S kt

hp lm gim bt s lng nhn cn thit iu khin mt cch chi

tit mt b gi v cng lm gim i s lng lu lng iu khinphn phi nhn cn thit.



21/84


Nhn v s lin kt nhn

Mt nhn c s dng xc nh ng dn cho mt gi i

qua. Mt nhn c mng hay c ng gi vo trong tiu lp 2

cng vi gi. B nh tuyn nhn kim tra cc gi vi ni dung nhn

ca n quyt nh chng k tip. Mi khi gi c dn nhn th

phn cn li hnh trnh ca gi qua ng trc mng c da trn

chuyn mch nhn. Gi tr nhn ch c ngha cc b, ngha l

chng ch lin quan n cc chng gia cc LSR.

Mi ln mt gi c phn loi nh mt FEC mi hay FEC ang

tn ti, mt nhn c phn b cho gi. Cc gi tr nhn nhn c t

lp lin kt d liu nm pha di. Vi cc lp lin kt d liu (nh FR

hay ATM), cc b nhn dng lp 2 nh l b nhn dng kt ni tuyns liu (DLCI: Data Link Connection Identifier) trong mng chuyn

tip khung (FR: Frame Relay) hay b nhn dng ng o (VPI:

Virtual Path Identifier)/ b nhn dng knh o (VCI: Virtual Channel

Identifier) trong mng ATM, c th c s dng mt cch trc tip

nh cc nhn. Cc gi sau c chuyn tip da vo gi tr nhn

ca chng.

Cc nhn c rng buc ti mt FEC nh mt kt qu ca mt vi

s kin hay chnh sch. iu ny ch ra mt yu cu cho rng bucnh vy. Nhng s kin ny c th hoc l cc rng buc d liu

hay cc rng buc iu khin. Rng buc iu khin hay c s

dng hn do c cc tnh cht m rng tin tin v c s dng

trong nh tuyn thng tin trong mng MPLS.

Cc quyt nh phn b nhn c th da trn cc tiu chun

chuyn tip, chng hn nh:

nh tuyn n hng ch. K thut lu lng.

a hng (Multicast).

Mng ring o (VPN: Virtual Private Network).

QoS.

Nhn c th nhng trong tiu ca lp lin kt d liu

(VPI/VCI ATM v DLCI FR ) hay trong lp m .

To nhn v phn b nhnC mt s phng php c s dng trong vic to nhn:



22/84


Phng php da trn hnh (topology-based): s dng

cc giao thc nh tuyn thng thng nh OSPF (Open

Shortest Path First) v BGP (Border Gateway Protocol: Giao

thc cng ng bin).

Phng php da trn yu cu (request-based): s dng

iu khin lu lng da trn yu cu nh RSVP (Resource

Reservation Protocol: Giao thc dnh trc ti nguyn).

Phng php da trn lu lng (trafic-based): s dng s

tip nhn ca gi phn b thng tin nhn.

Cc phng php da trn hnh v da trn yu cu l cc v d

v cc rng buc nhn iu khin, trong khi phng php da trn lu

lng l mt v d v cc rng buc d liu.Kin trc MPLS khng s dng mt phng php bo hiu

phn b nhn. Cc giao thc nh tuyn ang tn ti nh BGP,

c tng cng mang thng tin nhn trong ni dung ca giao thc.

RSVP cng c m rng h tr vic trao i nhn c

mang. IETF (Internet Engineering Task Force: Nhm c trch k

thut Internet) nh ngha mt giao thc c gi l Giao thc

phn b nhn (LDP: Label Distribution Protocol) cho bo hiu tng

minh v qun l khng gian nhn. S m rng ti giao thc LDP c

bn cng c nh ngha h tr nh tuyn tng minh da

trn cc yu cu v QoS v CoS. Nhng s m rng ny c lu gi

trong nh tuyn da trn rng buc (CR: Constraint-based

Routing) - nh ngha giao thc LDP.

Mt tng kt v cc lc khc nhau cho vic trao i nhn nh

sau:

LDP - nh x cc ch IP n hng vo cc nhn. RSVP, CP-LDP - c s dng cho k thut lu lng v t trc ti

nguyn.

Multicast c lp giao thc - c s dng cho vic nh x nhn cc

trng thi a hng.

BGP cc nhn bn ngoi (VPN).

ng dn chuyn mch nhn (LSP)

Mt tp hp MPLS cc thit b c cho php biu din mtmin MPLS. Trong mt min MPLS, mt ng dn c thit lp cho



23/84


mt gi c di chuyn da trn mt FEC. LSP c thit lp trc

truyn dn d liu. MPLS cung cp 2 chc nng sau thit lp

mt LSP:

nh tuyn theo tng chng (hop by hop routing): Mi LSR

la chn mt cch c lp tuyn k tip vi mt FEC cho trc. Ph-

ng php ny l tng ng vi phng php c s dng hin nay

trong cc mng IP. LSR s dng mi giao thc nh tuyn c th nh

OSPF, giao din mng-mng ring ATM (PNNI: Private Network to

Network Interface), etc

nh tuyn tng minh (ER:Explicit Routing): nh tuyn t-

ng minh tng t vi nh tuyn ngun. LSR li vo (ngha l LSR

ni m dng d liu bt u ti mng u tin) xc nh danhsch cc node m ER-LSP i qua. ng dn c xc nh c th

l khng ti u. Dc ng dn cc ti nguyn c th c t trc

m bo QoS cho lu lng d liu. ng ny lm gim nh cho k

thut lu lng thng qua mng v cc dch v khc nhau c th c

cung cp bng cch s dng cc lung da trn cc chnh sch hay

cc phng php qun l mng.

LSP thit lp cho mt FEC v bn cht l khng n hng. Lu

lng ngc li phi s dng LSP khc.

Khng gian nhn

Cc nhn c s dng bi mt LSR vi cc rng buc FEC-nhn

c lit k nh sau:

per platform Cc gi tr l duy nht vt qua ton b LSR. Cc

nhn c b tr t mt thng cha nhn chung. Khng c 2

nhn c phn b trn cc giao din khc nhau c cng gi

tr. per interface Vng nhn (phm vi nhn) c kt hp vi cc

giao din. Cc thng a nhn c nh ngha cho cc giao

din v cc nhn c cung cp trn cc giao din ny c

nh v t cc thng tch bit. Gi tr cc nhn c cung cp

trn cc giao din khc nhau c th ging nhau.

Hp nht nhn

Dng lu lng n t cc giao din khc nhau c th c kt

hp cng nhau v c chuyn mch bng vic s dng mt nhn



24/84


chung nu chng ang i qua mng hng ti cng mt ch cui

cng. iu ny c bit nh l s hp nht lung hay kt hp cc

lung.

Nu mng truyn ti nm bn di l mt mng ATM, cc LSR c th

s dng hp nht ng o (VP) hay knh o (VC). Trong kch bn

ny, cc vn an xen t bo xut hin khi nhiu dng lu lng

c kt hp trong mng ATM, cn phi c trnh.

S duy tr nhn

MPLS nh ngha s c x cho cc rng buc nhn nhn c t

cc LSR, khng phi l chng k tip vi mt FEC cho. Hai

ch c nh ngha:

Bo ton (conservative) Trong ch ny, cc rng bucgia mt nhn v mt FEC nhn c t cc LSR khng l

chng k tip cho mt FEC cho trc b hu b. Ch ny

cn mt LSR duy tr s nhn t hn. y l ch c

khuyn khch s dng cho cc LSR ATM.

T do (liberal) Trong ch ny, cc rng buc gia mt

nhn v mt FEC nhn c t cc LSR khng l chng k tip

vi mt FEC cho trc c gi nguyn. Ch ny cho php t-

ng thch nhanh hn vi cc thay i cu hnh v cho php

chuyn mch lu lng ti cc LSP khc trong trng hp c s thay

i.

iu khin nhn

MPLS nh ngha cc ch cho vic phn b nhn ti cc

LSR ln cn nh sau:

c lp (Independent) Trong ch ny, mt LSR nhn

dng mt FEC no v ra quyt nh rng buc mt nhnvi mt FEC mt cch c lp phn b rng buc n

cc thc th ng mc ca n. Cc FEC mi c nhn dng bt

c khi no cc tuyn (route) tr nn r rng vi router.

C th t (ordered) Trong ch ny, mt LSR rng buc

mt nhn vi mt FEC no nu v ch nu n l router li

ra hay n nhn c mt rng buc nhn cho FEC t LSR

chng k tip ca n. Ch ny c khuyn ngh s dng

cho cc LSR ATM.



25/84


1.2.5. Cc c tnh hot ng, iu hnh ca MPLS

Cc bc sau phi c thc hin vi mt gi d liu i qua mtmin MPLS:

To v phn b nhn. To bng ti mi router.

To cc ng dn chuyn mch nhn (LSP).

Chn/tm kim bng nhn.

Chuyn tip gi.

Ngun gi d liu ca n ti ch. Trong mt min MPLS

khng phi tt c lu lng ngun l cn thit c chuyn qua cng -ng dn. Ph thuc vo c tnh lu lng, cc LSP khc nhau c thc to cho cc gi vi cc yu cu CoS khc nhau.

Trong hnh 1.5, LER1 l router li vo v LER4 l router li ra

Hnh 1.5: S to ra LSP v chuyn tip cc gi thng qua mtmin MPLS

Cc bc sau y minh ho hot ng MPLS tc ng ti gi d liu

trong mt min MPLS.

To & phn b nhn

Trc khi lu lng bt u, cc router quyt nh rng buc mt

nhn vi mt FEC xc nh v xy dng bng ca chng.


LSR1

LSR2

LSR3

LER2

LER1

LER3

LER4

Ngun

ch

Lung d liu

Cc yu cu nhn Phn phi nhn

17


26/84


Trong LDP, cc router ng xung khi to s phn b cc nhn v

rng buc nhn/FEC.

Ngoi ra, cc c tnh lin quan lu lng v kh nng MPLS c tho

thun bng vic s dng LDP.

To bng

Ti pha nhn cc rng buc nhn, mi LSR to cc li vo trong c s

thng tin nhn (LIB : Label Information Base).

Ni dung ca bng s xc nh nh x gia mt nhn v mt FEC.

nh x gia cng vo v bng nhn u vo ti cng ra v bng

nhn u ra.

Cc li vo c cp nht bt c khi no s ti m phn v rng

buc nhn xy ra.To ng dn chuyn mch nhn .

Nh c biu din bng ng ngt qung trong hnh 1.5, cc LSP

c to phng ngc li vi s to cc li vo trong cc LIB.

Chn/tm kim bng nhn

Router u tin (LER1 trong hnh 1.5) s dng bng trong LIB

tm chng k tip v yu cu mt nhn ch FEC xc nh.

Cc router ch ln lt s dng nhn tm chng k tip.

Mi ln gi chm ti LSR li ra (LER4), nhn c xo b v gi ccung cp cho ch.

Chuyn tip gi .

LER1 c th khng c nhn no cho gi ny khi l ln u tin

xy ra yu cu ny. Trong mt mng IP, n s tm s ph hp a

ch di nht tm chng k tip. Cho LSR1 l chng k tip

ca LER1. LER1 s khi to mt yu cu nhn chuyn ti LSR1.

Yu cu ny s pht thng qua mng. Mi router trung gian s nhnmt nhn t router pha sau n bt u t LER2 v i ln trn cho

n LER1. Thit lp LSP c ch bo bi ng xanh da tri gy

khc bng vic s dng LDP hay bt k giao thc bo hiu no

khc. Nu k thut lu lng c yu cu, CR-LDP s c s dng trong

vic quyt nh thit lp ng dn thc s chc chn yu

cu QoS/CoS c tun th.

LER1 s chn nhn v chuyn tip gi ti LSR 1.



27/84


Mi LSR ln lt, ngha l LSR2 v LSR3, s kim tra nhn vi cc gi

nhn c, thay th n vi cc nhn u ra v chuyn tip n.

Khi gi ti LER4, n s xo b nhn bi v gi s ri khi min MPLS v

phn pht ti ch.

1.2.6. Kin trc ngn xp trong MPLS

Cc thnh phn MPLS ch yu c th c phn chia thnh ccphn sau:

Cc giao thc nh tuyn (IP) lp mng.

Chuyn tip bin ca lp mng.

Chuyn tip da trn nhn mng li.

Lc nhn.

Giao thc bo hiu phn b nhn.

K thut lu lng.

Kh nng tng thch vi cc lc chuyn tip lp 2 khcnhau (ATM, FR, PPP: Point to Point Protocol).

Hnh 1.6 m t cc giao thc c th c s dng cho cc

hot ng MPLS. Module nh tuyn c th l bt c giao thcno trong cc giao thc cng nghip ph bin. Ph thuc vo mi

trng hot ng, module nh tuyn c th l OSPF, BGP hay

PNNI ca ATM, etcModule LDP s dng TCP truyn dn tin

cy cc d liu iu khin t LSR ny n LSR khc trong sut

mt phin. LDP cng duy tr LIB. LDP s dng UDP trong sut qu

trnh khm ph ca n v trng thi hot ng. Trong trng thi

ny, LSP c gng nhn dng cc phn t ln cn v cng nh s c

mt ca chnh cc tn hin ca n vi mng. iu ny c thc

hin thng qua trao i gi hello.



28/84


Hnh 1.6: Ngn xp giao thc MPLS

IP Fwd l module chuyn tip IP c in, n tm kim

chng k tip bng vic so snh ph hp vi a ch di nht

trong cc bng ca n. Vi MPLS, iu ny c thc hin ch bi cc

LER. MPLS Fwd l module chuyn tip MPLS, n so snh mt nhn vi

mt cng u ra v chn s ph hp nht vi mt gi cho.Cc lp

c biu din trong hp vi ng gp khc c th c thc hin

bng phn cng hot ng nhanh v c hiu qu.

1.3. Tng kt chngTrong chng 1 trnh by mt s vn c bn ca chuyn

mch nhn a giao thc- MPLS, mt s vn lin quan n cng

ngh ny nh: Khi nim, cch thc hot ng, cc thut ng, hot

ng, sng t mt cch khi qut nht v cng ngh MPLS. Ch-

ng tip theo se trnh by v cch thc qun l mng vin thng

qua cc h thng qun l hin hnh.


Routing

UDPTCP

IP Fwd

PHY

LDP CR LDP

LIB MPLS Fwd

20


29/84

n tt nghip i hc Chng 2: Qun l mngtrong mng vin thng

Chng 2:

Qun l mng trong mng vin thng

2.1. Gii thiu chung v qun l mng.Cc thit b c trin khai trn mng c thng minh ngy

cng cao, v vy mt iu rt th v khi suy ngm v qun l

mng. Nu cc thit b rt thng minh th ti sao phi lo lng v

vn qun l mng?. Khi cc phn t mng (NE) khng c kh

nng t gii quyt, th nhiu mng doanh nghip a ra mt h

thng qun l mng (NMS) ring cho h. y l mt s nguyn nhn

gii thch ti sao qun l l mt vn ca doanh nghip v cc

nh cung cp dch v SP cn: Mt NMS duy tr cc bn tin hu dng v kim tra hiu qu

ca hnh ng (action) cu hnh trc .

NMS c th d dng hu dng cho cc dch v mng din rng

ging nh k thut lu lng, QoS, lp k hoch, sao d tr/ lu tr

(ca cu hnh d liu).

NMS cho php truy nhp nhanh bng cch mc nh mng

mt vi phng php x l. Cho v d, nu mt mng cha ng

nhiu mch o c nh ATM (PVCs) v c s tht bi trong lin

kt, sau cc thit b chuyn mch khng t ng phc hi

bi v cc PVC khng s dng bo hiu. Trong tnh hung ny,

s can thip ca ngi qun l mng ph thuc vo s lu tr cc

lin kt b ph v, khi c s lu tr ny, sau cc lin kt s -

c kt ni li. V d ,cc doanh nghip c th tng ti hn li vi

gi tr quyt nh ph hp vi tnh nghim ngt ca hp ng

dch v. NMS h tr cu hnh mng cc mng sau khi phn cng c

thm vo. Khi mng m rng, cc thit b chuyn mch mi v

cc router mi c thm vo, n cn thit mang cc thit b

mi ti cc dch v nhanh. Mt h thng qun l mng c th h

tr x l trn lu lng, cho php mt s lng ln cc hot ng t

ng, ging nh cng mt lc c th to ra hng trm (thm ch

hng nghn) cc mch o nh ATM PVCs hoc MPLS LSPs.



30/84


Cc h thng qun l mng c th cung cp iu khin cho

mng rng qua cc i tng h tr cho cc dch v. H thng

qun l c th to ra hng nghn bn tin thc v vit chng ln

c s d liu dch v. Cc thu bao o sau c th cp nht

thng tin nh vic chng kt ni n mng.

Mt iu rt tt ca NMS l m rng ci nhn tng quan v

ngi vn hnh.

Qun l mng cung cp mt phng tin gi cho cc mng chy

theo th t. N bao gm lp k hoch , m hnh v hot ng

chung, n cng c th cung cp cc lnh v iu khin phng

tin. Ni rng ra, cc vng chc nng ph thuc vo mng em li

hiu qu: Li: Tt c cc thit b ti vi im c th b li v cc kt ni

o, cc lin kt, cc giao din c th i ln hoc xung. iu

ny c th l tt c cc nguyn nhn pht sinh li d liu

mng.

Cu hnh: Tt c cc thit b hng ti s ph thuc vi kiu cu

hnh. S thit lp cu hnh c th l ghi v c t cc thit

b.

B m: Thc n cho dch v l mt thnh phn quan trng

trong qun l mng doanh nghip. Chc nng ny c th np

sau vic s dng ti nguyn. Ging nh thit b dial-up, mt

phn o l rt tt cho vic kim li thc n qui thun bi

mt nh cung cp dch v.

S thc thi: S ngi s dng v bng tn th cn ln mnh,

l yu t cn thit cho s thc thi.

S bo mt: S tn cng vo mng c th bao gm: truy cptri php, thay i d liu, hoc n cp v hn th na. S

bo mt l cn thit m bo mng c bo v.

2.2. Cc yu cu c bn vi mt kin trc qun l

mng


Min qun l

Min b qun l

Khch hng Khchhng

Nh cung cp dchv

H thngqun l

truyn thngdoanh nghip

Chc

nng NEOAMTngi cquanB ghpknh

iukhin ng

i sdngcui/ngi sdngcui

Cng ty khai thcvin thng

Qun kdch v

Qun lti nguyn

Thnh phn mng

Cc thnhphn

dch v

Ccthnh

phn tinguyn

22


31/84


Hnh 2.1: Mi quan h trong h thng qun l mng

Khi pht trin mt kin trc qun l mng khc phc skm hiu qu, gi thnh cao, v phc tp ca mi trng mng hin

ti, ngi ta xem xt nhiu kha cnh v kinh doanh, v k thut v

dch v.

Cc kha cnh v dch v:

- Cho php nhanh chng trin khai cc dch v mi trong c mi tr-

ng mng v mi trng h thng qun l mng.

- Thc y vic khi to dch v nhanh hn

H thng qun l mng phi c kin trc phn tn, theo kin trc

hin i mt cch mm do, cho php nh cung cp dch v c th

d dng tho mn nhu cu ca khch hng trong tng lai. Cc i

hi ny bao gm: Trin khai v khi to dch v, tnh cc v in ho

n, tnh nng truy nhp trc tuyn mt cch nhanh chng. Phn

mm v cc tnh nng mi phi bo o rng dch v khch hng

phi c tnh bng pht ch khng phi bng ngy hay tun.

Cc kha cnh v cng ngh:- Thch thc v kh nng qun l v phn phi d liu mt cch

hiu qu trn ton mng.

- Chm dt kiu mng chng cho vt l hin ti cn thit cho

vic trin khai cc ngun ti nguyn mng, cc dch v mng v cc

h thng qun l mng lin quan.

Qun l d liu i hi mt khon chi ph ln t pha nh cung

cp dch v bo m tnh chnh xc, tnh d phng trong ton

b hot ng ca nh khai thc. Do vy kin trc qun l mng mi



32/84


phi c kh nng phn phi s liu trn tt c cc lp ca mi trng

qun l mng h tr cc thnh phn mng thng minh INE x l s

liu v chyn tip thng tin cho cc h thng qun l mng trn c

s ng cp peer-to-peer. Cn phi t b vic qun tr cc c s

d liu d phng mt cch th cng.

2.3. Cc thnh phn cng c bn trong mt h

qun tr mngChng ta m t cc thnh phn cng bn trong chng phi hp vi

nhau to nn mt NMS. Ging nh chng ta thy, qun l mng l

phc tp. y c nhiu gii php cho s pht trin NMS. Trong ch-

ng ny m t mt cu trc c th. Vng phn cng NMS di y s

c m t gm c:- Thnh phn Server Side.

- Mng thu khng ng b

- Mng gi

- Truy nhp c s d liu

- Thnh phn Client Side

- Thnh phn Middleware

- Miu t d liu- Giao din pha Bc

Knh ngoi bng l mt vn ng ch bi v n cho php

lu lng qun l mng s dng s dng knh tch ri t mt knh

s dng cho d liu (khi nim ny tng t vi cc ng bo hiu

c thc hin trong cc mng SS7). iu ny gip cho trnh cc vn

tc ng song hnh.

S tc nghn lu lng dch v lm s qun l cc knh kh khn.

Server c trng cung cp cc chc nng di y:. Bo dng Client cc yu cu ca ngi s dng

. a ra cc hot ng cung cp ging nh cch qun l Agent

MIB (Chn vo bng cc thc th, cp nht hoc xo b cc i tng

tn ti)



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Hnh 2.2: Cc thnh phn NMS v cc lung d

liu

. Cung cp cc dch v c bit, ging nh NE c s v cu

hnh sao lu tr c

s d liu, khng lu tr v phn phi.

. iu khin thng bo t mng.

Tt c cc Server c cc chc nng h tr c th cho a ra kt

qu trong truy cp d liu c s. Cc khun dng d liu c s gn

kt vi nhau c mt h thng tng th.

Hnh 2.3: Qun l giao din terminal- server.

Client hng ti s dng c s d liu ngay lp tc thay v da vo

Server qun l c s d liu. Bn ghi Client hot ng ging

nh to ra FR hoc cc mch o ATM.


Client

1

NMS

Telnet/

HTTP/HTTP

S/IPSec

(ti OSS)

C s dliu

Mng

vinthng

Knh ngoibng

SNMP

SNMPSet/Gets/

Responses

H thngqun lmng Server u cui

(vi SNMPAgent)

PSTN

Telnetto A

Interface A

Modem X

T3

Modem Y

Kt nicho s

T1

2 xT1

25


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Client lu tr tiu ca lch trnh hot ng v kt hp cc

kt qu. Cc Client c th da trn tiu chun trnh duyt Web,

y c th c nhiu Client (c kh nng l 100 nt hoc mng

rng ln), y s lng mng x l l mt quyt nh thit k

quan trng.

Chng ta tha nhn rng ngi s dng i khi mun truy nhp h

thng menu, cung cp bi kt ni t xa. Mt kt ni cho l mt

thit b cho php cc knh TDM l chun b cho cc mch bng

tn cao hn hoc thp hn.

Hnh 2.3, minh ho 1 T3 vo ra khi n l 1 T1 v T1s c trch

ra v truyn dn ti trong hng khc. Trong v d ny, kt ni dc

cho l mt ng ring, n cung cp mt giao din ni tip choqun l mng s dng mt h thng menu text hn l SNMP. N c

th tm thng qua modem X kt ni vi giao din A trn server u

cui ni ht. Ngi s dng kt ni n giao din A s dng telnet v

c th bt u gi cc lnh n modem X, cho v d, quay s ti

modem X theo cch ny, trc khi giao din A c th s dng, n phi

c cu hnh. V server u cui cho php s dng SNMP

thit lp nhn cu hnh t cc giao din ni tip ca chung. V

vy, ngi s dng mun cu hnh giao din no th gi tr itng MIB cho giao din gm:

. Bitrate (tc bit)

. Parity (chn l)

. S ca bit d liu

. S ca bit bt u

. S bit Stop

Cch qun l OSI s dng m hnh hng i tng ca cc thngtin qun l. Cc biu hin c quan tm (nhiu, li, di ca

hng ch) l cc dng khc nhau ca mt chui thi gian. Ngi ta c

th nh ngha mt nhm vt th b qun l chung m t cc

s liu ca cc hot ng v cc chui thi gian tnh ra cc chc

nng ca chui thi gian v d cc phin bn). Vt th b qun l

cng c th cung cp cc thng bo v nhng s kin chung (khi

mt s chc nng ca chui thi gian vt qu ngng). Nhm vt th

b qun l sry thi gian chung c th c phn ra thnh cc nhm



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vt th to ra cc phin bn ca cc vt th qun l ny trong c s

d liu ca thit b. Agent thit b c th gim st tng ng x ca

mng v ghi li cc gi tr tng ng trong cc phin bn vt th qun

l ny. Hn th na, h thng c th ngh cc Agent nhn

thng bo v cc s kin m t nhng thay i ln ca t l li,

hoc ca hng ch qu y ca b vi x l.



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2.4. Qun l mng theo m hnh OSI2.4.1. Khung lm vic ca m hnh OSI

Mc tiu ca m hnh OSI (Open System Interconnection) l

m bo rng bt k mt x l ng dng no u khng nh hngti trng thi nguyn thu ca dch v, hoc cc cc x l ng dng

c th giao tip trc tip vi cc h thng my tnh khc trn cng

lp (nu cc h thng cng c h tr theo tiu chun ca m hnh

OSI). M hnh OSI cung cp mt khung lm vic tiu chun cho cc

h thng. Cu trc phn lp c s dng trong m hnh v c 7 lp,

c th phn loi thnh 2 vng chnh.

Lp thp cung cp cc dch v u cui - ti - u cui p ng

phng tin truyn s liu (cc chc nng hng v pha mng). Lp cao cung cp cc dch v ng dng p ng truyn thng tin

(cc chc nng hng v ngi s dng).

M hnh OSI c th chia thnh ba mi trng iu hnh

Mi trng mng: lin quan ti cc giao thc, trao i cc bn tin v

cc tiu chun lin quan ti cc kiu mng truyn thng s liu khc

nhau.

Mi trng OSI: Cho php thm vo cc giao thc hng ng dng vcc tiu chun cho php cc h thng kt cui trao i thng tin ti

h thng khc theo hng m.

Mi trng h thng thc: xy dng trn m hnh OSI v lin quan ti

c tnh dch v v phn mm ca ngi sn xut, n c pht

trin thc hin nhim v x l thng tin phn tn trong thc

t.

Cc c tnh ca mi trng iu hnh OSI

o Chc nng ca cc lp, giao thc nh ngha tp hp canhng quy tc v nhng quy c s dng bi lp giao tip vi mt

lp tng ng tng t trong h thng t xa khc.

o Giao tip gia cc lp.

o Mi lp cung cp mt tp nh ngha ca nhng dch v ti

lp k cn.

o Mt thc th chuyn thng tin phi i qua tng lp.

Chc nng qun l h thng s c thc hin qua cc lp ca mhnh OSI. N chnh l mt tp chc nng nh ngha bi nh qun



37/84


l. Tp chc nng ny ph thuc vo yu cu qun l v c cha

trong ng dng. H thng qun l mng theo OSI l mt tp cc tiu

chun qun tr mng c thc hin bi ISO. Cc khuyn ngh X cho

mng d liu v truyn thng h thng m nh ngha cho cc

tiu chun qun l. V d : X.700-X.709 kin trc khung qun l h

thng, X.710-X.719 giao thc v dch v truyn thng qun l,

X.720-X.729 Cu trc ca thng tin qun l.

Trao i thng tin qun l: c thc hin theo 3 hng: Qun l h

thng, qun l lp v iu hnh lp.

Nhim v qun l h thng c thc hin t lp ng dng v

s dng khi nim thc th ng dng qun l h thng (SMAE)

qun tr h thng. Giao thc lp ng dng thng c coi l giao thcmnh nht, n c kh nng trao i nhiu thng tin qun l, p

ng tt cc yu cu qun l, l cch tip cn nhanh nht ca ngi

qun l h thng vi h thng. Nhim v qun l lp ca m hnh

OSI thc hin qun l cc i tng thuc lp, v trao i thng tin

qua h thng giao thc ti cc lp k cn.

i tng b qun l, qun l thng tin v MIB.

i tng b qun l nm trong cc lp khc nhau thuc m hnh

OSI, v thng tin qun l nm trong c s d liu thng tin qun l(MIB). MIB c coi l mt dng c s d liu, ni dung ca c s d

liu ny khng cha i tng b qun l m ch cha cc thng tin

lin kt vi cc i tng ny. h thng qun l lp thc hin duy tr

mi lin kt gia i tng b qun l v thng tin trong c s d

liu. V vy, nu xut hin li ti qun l lp th thng tin trong c

s d liu khng phn nh ng thc trng qun l ca h thng.

C s t h n g t i n

q u n l

L M

L M

L M

Q u n l l p

O : i t -

Hnh 2.4: Cc thnh phn ca h thng OSI n2.4.2. Khi qut v qun l h thng theo OSI (SMO)



38/84


39/84


Hnh 2.7: Trao i thng tin gia manager- Agent


SMAE

Managedobjects

Vai tr Agent

CMIPSMAE

Vai tr Manager

31


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2.5. Giao thc qun tr mng n gin SNMPGiao thc qun tr mng n gin (SNMP)c thit k trn m

hnh Manager/Agent. c gi l n gin v theo m hnh ny,

Agent i hi phn mm ti thiu. Hu ht cc chc nng c chatrong h qun tr. Kin trc c bn ca SNMP c ch ra trn hnh

2.8 sau y.

Manager SNMP to ra kt ni ti Agent thc hin cc lnh

trn thit b mng t xa, nhn thng tin qun l cc thit b

thng qua h tng mng truyn thng. MIB nm ti cc Agent gm

cc bin nhn dang SNMP. Tu thuc vo cc lnh c gi ti m

Agent s c cc tc ng thch hp.

H qun tr gi cc lnh get, set, getnext tm kim ccbin n hoc i tng hoc thit lp gi tr ca mt bin

n. H b qun tr gi thng bo ca s kin gi l trap, khi xy

ra vt ngng.

Hnh 2.8: Kin trc c bn ca SNMP

2.5.1. Giao thc SNMPv1

Phin bn c gii thiu ln u nm 1990. (SNMP,RFC 1157)

s dng UDP (RFC768) trao i bn tin qua cng 161,162 (truy

vn, trap) .


Cc bn tinSNMP

H thng qun l mngSNMP

ng dngqun l mng

SNMP Manager

UDP

IPLink

get set .response trap

Thit b qun l mngSNMP

Qun l ti nguyn

SNMP Manager

UDP

IPLink

get set .response trap

MIBi tng qun l SNMP

Mng vin thng

32


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SNMPv1 cung cp 4 iu hnh : 2 iu hnh khi phc

d liu, 1 t d liu v 1 cho thit b gi thng bo.

Get, s dng ly thuc tnh i tng

Get-next ly thuc tnh i tng thng qua cy MIB.

Set, s dng thay i thuc tnh i tng.

Trap, thng bo khn cp c gi i t Agent (ngng cnh bo).

Cc iu hnh trn c nhng vo trong bn tin SNMP. Khun dng

bn tin nh sau:

Trng Version ch th phin bn ca SNMP (SNMPv1:0);

Version Community SNMP PDU

Type Requid 0 0 Veriable binding

Hnh 2.9: Khun dng bn tin SNMPv1

Trng Community l mt chui xc nhn pasword cho c tin

trnh ly v thay i d liu. SNMP PDU cha iu hnh gm:

kiu iu hnh (get, set), yu cu p ng (cng s th t vi bn

tin gi i) n cho php ngi iu hnh gi nhiu bn tin ng thi(requid). Bin ghp gm cc thit b c c t trong RFC 2358 v

cha c gi tr t ti i tng.

Bn tin TRAP c gi i t Agent, mt thit b c th gi i cc

thng tin nh: dung lng b nh, ngi s dng li truy nhp Log in. Cc

thng tin ny lm gim ti x l cho cc manager khi n khng phi

kim tra nh k.

Cu trc thng tin qun l (SMI, RFC 1155) l mt tp cc lut

c t thng tin qun l trn chnh thit b. Cc i tng b qunl c sp xp theo hnh cy. Chnh v vy m thng tin trong

SNMP PDU c dng nh sau:



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Hnh 2.10: Cu trc thng tin SNMP PDU

i tng sysUptime c nhn dng 1.3.6.1.2.1.1.3 v nm trong

nhnh 1.3.6.1.2. Nhn dng ny c gi l nhn dng i tng v

c s dng truy nhp i tng trong MIB. (Ch c l c truy

nhp )2.5.2. Cu trc SNMPv3

SNMPv3 (FRC2575) nh a ch cho hai vng chnh, qun tr v

bo mt.


iso

org

dod

internet

directory Mib-2(1) private

systeminterface

at(3) Ipv4

sysdecrSysobjectsyscontactsysnamesyslocationsysServiceSystime

DispatcherH thng conx l bn tin

H thng conbo mt

H thng coniu khin truy

nhp

SNMP Engine

B to lnhB thu thng

bo

H thng con chuyntip Proxy

B phc plnh

B to thngbo Khc

Cc ng dng

Thc th SNMP

34


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Hnh 2.11: Kin trc thc th ca SNMPv3.

Cc thnh phn ca c cu SNMP gm c :

iu phi (Dispatcher)

Phn h x l bn tin (Message Processing Subsystem)

Phn h bo mt (Security Subsystem)

Phn h iu khin truy nhp (Access Control Subsystem)

Phn h iu phi x l bn tin gi v nhn, khi n nhn c

bn tin n s xc nh phin bn ca SNMP v gi bn tin ti phn

h x l bn tin tng ng, phn h x l bn tin chia thnh 3

module nh sau:

Hnh 2.12: Phn h x l bn tin.

Gi s phin bn SNMP s dng l v3. Model SNMPv3 tch phn

d liu ca bn tin gi ti phn h bo mt gii nn v nhn

thc. Phn h bo mt cng c nhim v nn d liu. Cu trc

module ca phn h bo mt nh sau:

Hnh 2.13: Cu trc module ca phn h bo mt.

SNMPv3 tng thch hon ton vi SNMPv1v SNMPv2, n gmm hnh bo mt da trn ngi s dng v m hnh bo mt chung

x l SNMPv1,v2. Cu trc module ny n gin khi thm vo

cc module bo mt dng khc trong qu trnh pht trin. Khi s

liu c tch ra khi PDU v c gi ti ng dng thch hp qua

phn h iu khin truy nhp. Phn h iu khin truy nhp

chu trch nhim xc nh i tng b qun l v cch thc truy

nhp ti n. Hin nay ch c mt m hnh iu khin truy nhp(2003) nhng n c th m rng trong tng lai:


M hnhx l bn

tinSNMP v1

M hnhx l bn tinSNMP v2c

M hnhx l bn

tinSNMP v3

M hnhx l bn

tinkhc

H thng con x l bn tin

M hnh bomt kiu

ngi dng

M hnh bomt kiuchia s

M hnh bomt kiu

khc

H thng con bo mt

35


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Hnh 2.14: Cu trc phn h iu khin truy nhp.

M hnh iu khin truy nhp c th nhn thy (RFC 2575)

quyt nh ngi s dng no c th truy nhp (c, hoc t

trng thi) cho i tng qun l. M hnh ny c gi t ng dng

khi i tng c truy nhp.

Cc ng dng ca SNMPv3 (RFC 2273) l cc ng dng ni trong

cc thc th SNMPv3. Chng tr li cc bn tin SNMP nhn c, tora thng bo, c 5 kiu bn tin:

1. Command Generators To ra cc lnh SNMP c hoc t

li d liu.

2. Command Responders Tr li cc lnh v cung cp truy nhp ti

d liu.

3. Notification Originators Khi to bn tin trap.

4. Notification Receivers Nhn v x l bn tin trap.

5. Proxy Forwarders Chuyn cc bn tin gia cc thc th SNMP.

2.5.3. iu hnh SNMP

n v d liu giao thc (PDU) l mt khun dng bn tin m

manager v agent s dng trao i cc thng tin cc iu

hnh sau y l chung cho tt c cc phin bn ca SNMP hin

ang s dng:

GET

GET-NEXT

GET-BULK (SNMPv2,SNMPv3)

SET

GET-RESPONSE

TRAP

NOTIFICATION (SNMPv2, SNMPv3)

INFORM (SNMPv2, SNMPv3)

REPORT (SNMPv3)


M hnh iukhin truynhp kiu

quan st


khc


khc

H thng con iu khin truy nhp

36


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2.6. C s thng tin qun l trong SNMP2.6.1. Cu trc MIB

MIB cung cp m hnh c s d liu th bc cho cc thng tin

b qun l. Cc thng tin b qun l c ghi trong cc bin s bqun l v lu tr ti cc l ca mt cy tnh. SNMP tn dng cy

ng k ca ISO nh l mt th mc thng tin b qun l. Nh minh ho

ti hnh 2.15, ngi ta s dng cy ng k nh du cc nh

ngha ca cc tiu chun khc nhau.

Hnh 2.15: Cy ng k ca OSI MIB IIMi nt thuc cy c nh du bng mt tn (c im

nhn dng chung) v mt s (c im nhn dng tng i). Mt

nt c xc nh mt cch duy nht bng cch ni cc s trn ng

gc ca n. V d mt cy con c nhn l Internet c xc nh bi

ng 1.3.6.1. Cy con ny c t trong t chc Internet ghi

li cc tiu chun ca n.


Gc

CCITT (1) Hn hp ISO-CCITT (2)

ISO (1)Khuynngh (0)

Cu hi(1) C quan

Qun l (2)

Nh khaithc mng

(2)

Tiu chun(0)

C quanng k(1)

Thnhvin (2)

T chc c xc

nh(3)

Ftam

(8751) dod (6)

Internet(1)

Th mc(1) Qun l

(2)Th

nghim(3)

T nhn(4)

Doanh nghip(1)

mib (1)

37


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Hnh 2-17: Cy MIB Internet

Cy Internet c ba cy con lin quan n qun l, l:qun l,th nghim v ring. Cc cy con ny c s dng ghi

li cc MIB khc nhau theo chun Internet (MIB-II), cc chun MIB

ang c xem xt (RMON) v MIB thuc sn phm t nhiu nh

ch to thit b khc nhau (nh hnh 2.16 ):Tt nht l ta nn xem

xt cu trc ca cy nh mt phng tin thc hin hai mc

ch. Th nht, n cho ta mt c im nhn dng duy nht ca

cc thng tin b qun l. V d hnh 2-16 ch ra mt ng

1.3.6.1.2.1.1.1 dn ti t bo sysDesc cha cc thng tin m t v


Internet (1) [1,3,6,1]

Th mc (1) Ring (4)

ISO (1)

Hthng(1))

at (3)Giao din Imcp (5)udp (7)

trans (10) SNMP (11)

SysObjectld(2)

cmot (9)

ifTable (2) tcp (6) Egp (8)

Qun l (2) Th nghim (3), (4)

ip (4)

SysDes (1) ifentry (1)(0)

(0)

Bng ng kt ni TCP(13)

Bng ng kt ni TCP(13)

38


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h thng. Th hai, n cho php nhm cc thng tin lin quan ti mt

cy con. V d ti hnh 2-16, tt c mi thng tin b qun l gn d-

i h thng Internet c ghi di cy con 1.3.6.1.2.1.1. hy nh rng

cu trc th mc ca thng tin b qun l l tnh. V tr ca thng

tin trn cy MIB c xc nh ti thi im ngi ta thit k MIB.

Hnh 2.16 minh ho t chc ca cy MIB-II Internet. Mc tiu

ca MIB ny l cung cp cc bin s b qun l chung x l MIB-

II ra thnh 11 cy chc nng con. Mi cy con i din cho mt

nhm bin s lin quan trc tip n thc th b qun l (thc th

giao thc nh IP hoc TCP). Cc cy ny li tip tc c a ra thnh

cc cy con di na. Ti y ca cy l l, l c s dng nh

du cc bin s b qun l thuc mt loi nht nh. Mt s l (nhsysDesc m t h thng) ch nh du mt thi im duy nht

ca bin s b qun l v ch i hi mt t bo lu tr duy nht.

Nhng l khc (nh tepConnState m t trng thi mt ng kt ni

TCP) c th ch dn nhiu thi im khc nhau. Cc thi im

khc nhau ny c t chc thnh cc ct t bo.

Cc ct ny to thnh mt bng m cc hng thuc bng ny

biu din nhng thi im khc nhau ca mt thc th (nh mt -

ng kt ni TCP hoc mt giao din).Vic nh ch dn truy nhp i vi cc thi im n l

mt vn n gin. T bo lin quan ti l nh vy c coi l con

ca l v c nh nhn l O

V d, bin s b qun l cha s nhn dng vt th ca h

thng (t bo bn di sysObjectld) c xc nh bi

1.3.6.1.2.1.1.2.0. iu ny c ngha l ng ti sysObjectld lin kt

vi O. Tuy nhin, cc s liu c xp thnh bng li i hi mt cch ch dn phc tp hn, bi v ta cn xc nh mi hng trong

bng mt cch duy nht (mt thi im ca mt thc th).

Cc thi im ca mt thc th b qun l cho trc (v d nh

giao din) c th thay i khc nhau gia cc h thng hoc theo

thi gian. Ngi ta s dng bng h tr s thay i ng .

Agent c th b sung thm hoc xo i cc u vo mi. Do ta

ch khng th nh ch dn cho cc hng ca bng mt cch tnh.

Bng cc ct cha kho, ngi ta c th xc nh u vo ca bng



48/84


mt cch duy nht. Ngi ta s dng ni dung ca cc ct cha kho

nh l ch dn. C kh nng c s dng trong bng giao din l a

ra mt ch dn c bit ng vai tr nh cha kho. Gi tr lu tr

trong ct ny cho php ta xc nh cc hng ct mt cch duy

nht. V d, gi s hng th ba thuc bng giao din c gi tr

ifIndex l 12, khi ifInError.12 xc nh phn t th ba thuc ct

ifInError.

C mt kh nng na c s dng trong bng ng kt ni

TCP, l s dng mt s t ct ng vai tr nh cha kho. Bn ct

cho ta

mt cha kha ca bng ng kt ni TCP. Gi tr ny c kt hpsau c im nhn dng ca ct ch dn gi tr thi im t-

ng ng mt cch duy nht. V d, gi s rng hng th ba ca

bng kt ni TCP cha cc gi tr ca cha kho nh sau:

(128.10.15.12,173,128.32.50.01,130). Trng thi ca ng kt ni

TCP tng ng c xc nh bng cch ghp c im nhn dng

ct trng thi ng kt ni TCP [1.3.6.1.2.1.6.13.1.1] vi gi tr ca

bn ct ch dn 128.10.15.12.173.128.32.50.01,130. R rng l k

thut nh ch dn ny c th dn n vic xc nh v truynhp cc bin s b qun l khng hiu qu. n gin ho vic

truy nhp, trong phin bn SNMPv2 ngi ta ci tin k thut

nh ch dn i vi s liu dng bng.

Tm li, trong giao thc SNMP, cc c s thng tin qun l MIB

c t chc di dng c s d liu th bc vi s liu b qun l c

lu tr ti cc l ca cy. Cc cy con c s dng biu th ni

dung logic, cn cc bin s b qun l c lu tr ti cc l cy. Ngita s dng cc bin s ny biu din cc thi im ca thc

th tng ng. Cu trc ca cy c s d liu ny c cc nh thit

k MIB nh ra mt cch tnh. Ch c s thay i m rng trong

cc gi tr ca c s d liu v trong vic to ra hay xo i cc

hng ca bng.

2.6. 2. Truy cp MIB

Ta c th nhn nhn SNMP nh mt ngn ng hi i vi cy

MIB. Chng trnh nh qun l s dng cc lnh GET, GET-NEXT



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truy xut d liu t MIB. p li hai n nguyn ny l GET-

RESPONSE tr li d liu di dng i bin s. Ta c th s dng c

hai n nguyn truy xut nhiu bin s b qun l. Lnh GET

trc tip ch ra tp hp cc bin s b qun l thng qua c

im nhn dng ng dn ca chng. iu ny rt hu ch cho

vic truy xut d liu dng thng thng (dng khng phi bng), bi

v ng truy nhp l tnh v bit trc. V d, truy xut s m

t ca h thng, lnh GET phi cha c im nhn dng ca t

bo, l 1.3.6.1.2.1.1.1.0.

GET-NEXT c s dng di chuyn trn cy v p dng cho

s liu dng bng. Ta c th th t truy xut s liu bng cch i li

trn cy MIB. Theo quy nh ca th t ny, th h thng truyxut s liu ti nt m trc ri n nt con t tri qua phi. Trong

bng, cc ct c nh th t t tri qua phi v cc hng t trn

xung di. Th t ny c gi l th t trc (preorder) v c minh

ho hnh 2-15.

Ta p dng GET-NEXT cho cc mc 10, 14 trong hnh 2-8

truy xut cc mc 11 v 15. Trong v d sau, ta cng xem xt mt

phn bng giao din nh minh ho di y.

GET v GET-NEXT cho ta phng tin truy xut d liu MIB.Bng n nguyn SET ta c th iu khin c ng x ca thit

b. SET thng c s dng khi to hnh ng ca Agent nh l

hiu ng ph i vi nhng thay i ca MIB. V d ta c th khi

ng mt th tc kim tra chun on bng cch t trng thi

hnh chnh ca thit b (thng qua SET) l th nghim. iu ny c

ngha l cc Agent phi ch ng gim st nhng thay i ca

MIB v khi to cc hnh ng cn thit. iu ny khng ging vicc h thng c s d liu th ng m s cp nht s liu

ch n thun l ghi li s liu. C mt nhc im ca vic truy

xut s liu bng lnh GET-NEXT trong SNMP, l h thng cn

phi truy cp mt hng ti mt thi im. iu ny c th lm

chm qu trnh i li trn cy, c bit trong trng hp bng ln.

Thng th h thng phi qut v truy cp ton b bng. khc

phc im ny, trong phin bn th hai SNMPv2 ngi ta thay



50/84


lnh GET-NEXT bng lnh GET-BULK. Lnh GET-BULK truy cp

mt s hng lin tc va vo mt

khung UDP. Ta c th nhn nhn vic ny nh l vic tng quan ho

lnh GET-NEXT ci thin thi gian truy cp i vi d liu dng

bng.

2.6.3. Ni dung ca MIB

Cu trc ca thng tin b qun l (SMI) cho ta mt m hnh

n gin v s liu b qun l. M hnh ny c nh ngha bi

mt ngn ng m phng c php d liu, l ASN.1. SMI m

phng su loi d liu, l b m, kiu (gauge), tch tc thi

gian, a ch mng, a ch IP v s liu khng trong sut

(opaque). B m c s dng din t s ly mu tch t cachui thi gian. Kiu (gauge) din t cc mu ca chui thi gian,

tch tc thi gian c s dng o thi gian tng i, cn loi

s liu khng trong sut th c s dng m t mt chui bit

bt k. Ngi ta cng s dng cc loi d liu c s chung nh s

nguyn chui octet, c im nhn dng vt th xc nh s

liu b qun l. Vic gii hn cc loi d liu trong SMI v hn ch

quy m ca cc hng mc s liu trong MIB lm gim nhiu

phc tp ca vic t chc lu tr, m ho, gii m s liu. Trong mi

trng Agent c ngun ti nguyn c hn th s n gin ho v

vic iu khin ngun ti nguyn l rt quan trng v gi mt vai

tr trung tm trong vic thit k SNMP.

SMI cng bao gm mt MACRO m rng c bit ca ASN.1 l

OBJECT-TYPE. Macro ny phc v nh mt cng c chnh xc

nh cc vt th b qun l ti l ca cy MIB. Macro OBJECT-TYPE

cho ta phng tin nh ngha bin s b qun l v gn chon mt loi d liu, mt phng php truy nhp (c, vit c/vit),

mt trng thi (bt buc, tu ) v mt v tr cy MIB tnh (c

im nhn dng ng). nh ngha ca Macro OBJECT-TYPE v ca

cc bin s b qun l c trnh by trong bng di y. Phn th

nht ca nh ngha MIB cho ta cc c tnh nhn dng ng

ny i vi cc mode bn trong ca cy MIB v c gn vo loi d

liu nhn dng vt th. Ta c th xc nh c im nhn dng

ca mt nt bng cch rng buc mt s vi c im nhn dng



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ca nt b ca n. Khi cc nt bn trong c xc nh ri, bng

Macro OBJECT-TYPE h thng c th to ra cc mode ti l cy. Cc

nt ti l cy ny xc nh loi d liu (c php) ca cc bin s b

qun l m chng lu tr. Cc nt l cy cng iu khin vic truy

nhp, xc nh trng thi v ng c im nhn dng vt th

truy nhp bin s b qun l. Di y l mt s im hu ch

cn lu v cc nh ngha ny v cch s dng chng.

1. Cc c im nhn dng vt th xc nh v tr ca cc

nt bn trong (nh system, Interfaces), hoc l trn cy MIB

(sysDeser, ifInErrors). Ta c th to ra c im nhn dng ca -

ng bng cch ghp ng m vi nhn ca nt (v d sysDeser =

{system 1}).2. Cc bng c to nn di dng chui ca cc hng. Cc hng

xc nh ra cc ct ca bng. V d, bng giao din c thit lp t

cc ct c dnh ring cho cc tham s giao din khc nhau. Cc

tham s ct khc nhau ny c ng k nh l di cy con ifEntry m

t trong bng.

3. Cc nh ngha cu trc MIB ch n gin cho ta mt cu

trc v c php. Ting Anh c s dng gii ngha cho cc bin

s khc nhau c th din gii ngha ca mt s bin s khc nhau.i khi ta khng th bo m vic tun th cc ng ngha.

4. H thng c th s dng cc nh ngha chnh thc ca

MIB to ra MIB v cu trc truy nhp chng. B bin dch s

dng cc nh ngha ny to ra cu trc c s d liu cho vic

lu tr MIB. iu ny lm n gin ho qu trnh pht trin MIB.

5. Vic trin khai MIB l c thc hin. Ta c th lu tr cc

s liu khng phi dng bng trong cu trc d liu tuyn tnh cnh. H thng cn to kh nng cho s liu dng bng thu nh

hoc m rng, khi cc hng ca bng b xo i hay c b sung.

Ta c th dng cu trc ca mt danh sch lin kt (Linked list) hoc

cy biu din cc s liu ng nh vy (cc bn ghi ca bng

c lu tr ti l cy).

Chng ta cn nhn nhn cu trc MIB theo cc h thng c s

d liu truyn thng. Ngi ta c th s dng ngn ng x l s liu

(DML) to ra h thng c s d liu v m t cu trc ca c s



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d liu. Ta c th coi m hnh SMI hoc cc phin bn m rng

ca ASN.1 nh l ngn ng DDL xy dng MIB. B bin dch MIB

cng tng t nh b bin dch DDL, c s dng to ra cu trc

c s d liu t mt chng trnh tru tng. Ta cng c th coi cc

n nguyn truy nhp giao thc nh ngn ng x l s liu DML.

Nhn trn quan im cc h thng c s d liu truyn thng th

ta c th coi SNMP nh l mt h thng c s d liu th bc n

gin m bn cht ca n do cc ngn ng DDL (SMI) v DML xc

nh (cc n nguyn giao thc). Bng s m t MIB Internet (MIB-

II) mt cch gn gn chng ta s kt thc mc ny y. Bng di

y tm tt li vai tr ca cc cy con.

2.7. Nhng im hn ch trong SNMP v MIB.2.7.1. M hnh thng tin b qun l

Vn cng nhc trong MIB: S liu b qun l c xc

nh ti thi im thit k MIB. S liu cn cho cc nh khai thc

hoc phn mm ng dng c th khng sn sng mt cch trc

tip cho MIB. V d, mt chng trnh ng dng i hi thng tin

v nhng thay i trong t l li bit, trong khi MIB ch cha b

m li trc tip. nh qun l phi thc hin vic tnh ton cc

thng tin cn thit. iu ny c ngha l h thng thng phi truy

xut mt lng s liu th ln, thng l khng thc t. Cc thnh phn

mm ng dng thng cn mc iu khin t l vi vic ly

mu cc ng dng x l h thng, ch khng ph thuc vo cc

quyt nh cng nhc ca nh thit k MIB. Vic thit k mt

MIB gim st t xa cng nhm thc hin mt bc quan trng

m bo s linh hot trong iu khin cc tin trnh gim st. Cc

chu trnh gim st c t cc tham s mt cch linh hot thuthp s liu hot ng. Cc tham s iu khin nhng quy trnh

ny c t chc trong mt MIB iu khin. Mt chng trnh ng

dng c th t (SET) cc u vo trong bng iu khin MIB

xc nh xem h thng s thu thp nhng s liu no no v

theo phng thc no. Bn thn s liu c lu tr trong MIB s liu

tng ng v c th truy xut bng lnh GET. Tuy nhin cn ghi nh

rng, bn thn cc th tc gim st c xc nh mt cch cng

nhc ti thi im thit k MIB.



53/84


Cn phi thc hin cc hnh ng qun l thng qua tc

dng ph ca lnh SET: Agent phi ci by cc truy nhp SET v

khi to th tc qun l tng ng. Cc hnh ng n gin khng

i hi tham s m cng chng tr li gi tr no (v d nh khi

ng h thng) cng c th c thc hin mt cch hu chTuy

nhin, c ch ca lnh SET khng tho ng cho cc hot ng i

hi phi truyn tham s. V d, ta hy xem xt mt chu trnh chn

on cng. Khi gi chu trnh i hi mt vi tham s v khi kt

thc, n s khi to. Khi chu trnh ny kt thc, h thng c th s

dng lnh GET ly gi tr khi tr li ca n. Nh qun l v

Agent cn phi thc hin ng b vic t (SET) cc bin s u

vo, cc bin s khi to v ly (GET) kt qu. Yu cu ng b txa c th phc tp, mt thi gian v thm ch c hi trong mi

trng a nh qun l. Nu nh nhiu nh qun l lin tip gi chu

trnh ny, chng c th gy nhiu phin nhiu cho nhau, i hi

c ch iu khin ng thi thng qua SET/GET.

2.7.2. M hnh truy cp thng tin

SNMP khng h tr cc cng c truy xut tch lu. V d,

vic truy xut ton b mt bng phi c thc hin thng qua lnh

GET-NEXT ly tng hng thuc bng . Thng thng, vic x

l thng tin qun l i hi phi truy nhp tt c cc hng ca bng.

Cc bng ln i hi s ln truy nhp rt ln. Nu ta h tr vic truy

nhp mt lng s liu khng hn ch th giao thc s tr nn phc

tp hn nhiu. Mt lnh ly thng tin duy nht c th vt qu dung l-

ng ca mt ln tr li. Giao thc cn c kh nng h tr cc chui tr

li. Cc phin bn m rng ca SNMP ch cho php truy xut mt l-

ng s liu hn ch bng vi kch thc ca khung tr li.SNMP khng c kh nng la chn (hay lc) s liu c

truy nhp. Vic qun l ch yu l x l cc iu kin ngoi l.

Nh qun l thng ch quan tm ti cc s liu phn nh cc ng x

khng bnh thng ca h thng. Mt c ch truy nhp s liu l t-

ng cn phi cho php cc nh qun l la chn s liu m h quan

tm ch khng phi bt h ly mt lng s liu v ch ln. Trong v

d tng i PBX, nh qun l SNMP c th ch quan tm ti cc s

my c tham s cht lng t di ngng. Nh qun l bt buc phi



54/84


ly ton b bng thu bao v qut n ti mi trng qun l. Nu

kch c ca bng ln (10000 thu bao) th vic qun l s rt km

hiu qu. Cn phi nn s liu mt cch ti a ti ngun thay v

ko chng qua mng ti nh qun l. Nu m rng cc chc nng

SNMP h tr vic truy nhp s liu mt cch c la chn th

cng phn no lm tng phc tp ca cc chc nng Agent v

ca cc giao din giao thclnh SET c th a n s phc tp v

c tc hi na.

Cu trc MIB khng bao gm cc iu khon din

t cc mi quan h phc tp gia cc thc th b qun l.

Trong v d v tng i PBX, h thng i hi mt bng ring cho

mi quan h gia cc cng v th mch thu bao. Nu mun truyxut s liu gn lin vi mt cng hoc mt th mch, th h

thng cn truy xut tt c cc bng lin quan ti cng th mch v

tp hp chng ti nh qun l. Mi ln, h thng ch c th c mt

hng ca bng, do vy vic so snh tng quan s liu n gin

nht gia cc thc th b qun l khc nhau cng i hi phi truy

nhp mt lng s liu ln. T phng din ca l thuyt c s d liu

c in, th c ch truy vn d liu ca SNMP khng h tr mi t-

ng quan gia cc thc th thng qua mi quan h. Mi tng quan cn thc hin trong mi trng qun l, do vy i hi phi truy

nhp ton b d liu lin quan vi nhau trc. Vic iu gii s liu

b qun l thng i hi phi x l mt lng ln tng quan s. Vic

so snh tng quan s liu ti mi trng qun l c th dn ti tnh

trng h thng phi truy nhp mt lng s liu qu ln.

2.8. Tng kt chng

Chng ny a ra mt cch nhn khi qut v qun l mngvin thng. H thng qun l mng a ra vi nhng c im c

bn v phn cng. Phng php qun l mng c la chn y

theo hng m hnh OSI. Trong phn ny cp n giao thc

qun l mng n gin SNMP cng vi MIB. MIB vi chc nng cung

cp m hnh c s d liu th bc cho cc thng tin qun l, n

kt hp cht ch vi SNMP trong hot ng qun l mng vin

thng. Hot ng c th ca MIB trong mt mng xc nh (MPLS)

s c cp trong chng sau.



55/84




56/84

n tt nghip i hc Chong 3: ng dng MIB trong qunl mng MPLS

Chng 3:

ng dng MIB trong Qun l mng MPLS

3.1. Gii thiu v cc gii php qun l MPLSCc i tng qun l MPLS

Trong mc ny ta ln lt tm hiu v cc i tng qun l mngMPLS.

i tng nh tuyn r rng (ERO)

Cc kho ti nguyn

ng hm v LSP

In segment (giao din vo)

Out segment (giao din ra)

Cross connect (chuyn mch)

Cc giao thc nh tuyn

Cc giao thc bo hiu

Cc hot ng nhn: tra cu, y, trao i, xo. K thut lu lng

QoS.

Nh chng ta bit, cch kh khn nht ca qun l cc mng nhMPLS l vn khng s dng bo hiu thit lp cc LSP. Ccphn t mng NE trong MPLS c th h tr bo hiu. Mt nguynnhn khc l vn iu khin tt c cc i tng, l mt vn

lin quan ti qun l mng n gin SNMP gp kh khn.i tng nh tuyn r rng (ERO)

Mt ERO l mt danh sch cc a ch lp 3 trong mt vng mngMPLS. Ging nh mt danh sch chuyn tip thit k (DTL) trongATM. N m t mt danh sch cc node MPLS m mt ng hm iqua. Mc ch ca mt ERO l cho php ngi s dng nh rtuyn m mt ng hm a ra. Theo ngha khc, n cho php ng-i s dng cng bc mt tuyn. ERO c th hoc khng r rng

hoc chnh xc. i tng nh tuyn r rng nh r tt c cc hop



57/84


trn ng. Mt ERO lu tr trong mt bng MIB trn node khi u,v c th c s dng bi nhiu hn mt ng hm khi u trnnode MPLS . Cc ERO khng s dng trong phng php cu hnhbng nhn cng ca cc LSP.

Cc ERO s c s dng bi cc giao thc nh tuyn (ging

nh RSVP TE) to ra cc ng hm. ng nh r trong ERO c

th thc hin c (v d, cc lin kt phi tn ti gia cc node

thit k) v bt k s ph thuc no nh cc ti nguyn bng tn.

Cc khi ti nguyn

MPLS cho php s dnh trc ti nguyn trong mng. iu ny cungcp phng tin cho nh vn hnh mng. Cc khi ti nguyn cung

cp mt phng tin cho bn tin v s thit lp bng tn, v sau chng c th thit k cc LSP c trng. Cc thnh phn ca mt

khi ti nguyn bao gm:

. Bng tn thu ln nht

. Kch c b lu lng ln nht.

. di gi

Mt LSP c th c mt s kt hp u cui - u cui bng

tn. LSP c thit k mang lung lu lng dc theo cc tuyn

c trng.ng hm v LSP

Cc ng hm MPLS miu t mt kiu xc nh cho cc tuyn

ng xuyn qua mng bi cc node vi cu hnh giao din vo (in

segment), chuyn mch (cross connect) v giao din ra (out

segment). Gi tin MPLS i vo ng hm, di t bn ny sang bn

kia mt ng thch hp, v c 3 c im quan trng a ra:

. Chuyn tip da trn c s tra cu nhn MPLS.. Cch i x ti nguyn l c nh, da trn pha thu ti thi

gian ca s to kt ni.

. Cc ng a ra bi lu lng l min cng bi ng chn trong s

thun li bi ngi s dng.

Cc ng hm v cc LSP cung cp cch tm cho lu lng vi cc

a ch IP ch c trng. Cc giao thc nh tuyn gi cc gi

trn cc ng hm c trng v LSP theo th t tm c a ch

IP thch hp.



58/84


In Segments v out segments (giao din vo- giao din ra)

In segment trn mt node MPLS miu t mt im vo lu lng.

Out segment m t mt im ra cho lu lng. Hai kiu i tng

segment l c s phi hp hp l s dng mt cross connect.

Cross connects (Kt ni cho)

Cross connects l i tng kt hp segment vo v ra vi nhau.

Node MPLS s dng thit lp cross connect quyt nh cch

chuyn mch lu lng gia cc segment. Bng Cross connect h tr

cc kiu kt ni di y:

- im ti im

- im ti a im

- a im ti imMt thc t cross connect c c mt trng thi hnh chnh v

trng thi hnh ng, cc trng thi hot ng ch th trng

thi thc ca cross connect trong node. Cross connect hot ng

th khng chuyn tip lu lng.

MPLS hp thnh cc giao thc nh tuyn IP ging nh OSPF, IS

IS, v BGP. iu ny thc hin bi cc giao thc ny c s

dng v cung cp qu nhiu nm. Hp nht chng sang cc chun

MPLS ci tin cc c hi trin khai MPLS. K thut lu lng m rng s

thm vo cc giao thc nh tuyn ngha l chng c th thng

bo c phn phi tiu s nh tuyn v ti nguyn (e.g bng

tn lin kt). y l quyt nh cho thit b v s to ra nh

tuyn min cng LSP (ie: ng hms). iu cui cng cho php thit

b ngi s dng tc ng a ra bi lu lng IP thng qua vng MPLS.

Cc giao thc bo hiu

Nh chng ta thy, vic to ra LSP v ng hm (nghm) c th t c hoc bng iu khin nhn cng (tng tnh cch ATMPVC to ra) hoc thng qua bo hiu. Cc kt nibo hiu c ti nguyn c thu, cc nhn, phn phi, v cc ngc chn bi cc giao thc nh tuyn nh RSVP TE hoc LDP.

3.2. c im MIB trong qun l mng MPLS bng

SNMP

3.2.1. V tr v u im ca MIB



59/84


MIB m t s phn chia khng gian tn gia cc Agent SNMP

v cc nh qun l mng. MIB hot ng tc ng n thit b

qun l c trin khai trn mng. Bi v, n ng vai tr trung tm

trong mng qun l . MIB cung cp vi nguyn tc trong c s

gia tng tng iu khin NE. Nh vy, Nu a ra cu hnh qun l

thch hp th mt NE th rt d c ci t, cu hnh v hot

ng trong mt mi trng NMS, y l mt thun li ln cho nh

qun tr mng. Nu chc nng NE, thit lp (v d, MPLS, Frame

Relay) rt d truy nhp (SNMPv3) sau i hi s tch hp v

quyn s hu c gim bt. Ngi s dng cui cng c nhiu thun

li ging nh vic ci to hoc mua thit b mi.

3.2.2. Mt s vn i vi i tng ca MIBSNMP c to ra cc dng mi trong cc bng MIB. Vn nm

y l hiu v ngha ca mi lin h gia cc ct bng.

Nu mt bng (ging nh bng ng hm MPLS, gm c rt nhiu

ct (column), khng phi tt c cc ct c th thit lp theo th t

to ra thc th c hiu lc. S kt hp khng qu cht gia cc

column l mt iu tt. y l mt cch tt kt hp cc khi

ca i tng MIB cung cp nhiu bng (tng t vi s lin kt c

s d liu thng thng). Mt cch rt c bit, khi cc bng c th

dng li (v d, ging nh trong ng hm MPLS, bng hop cho EROS

v ng hm MPLS, bng ti nguyn cho bng tn dnh trc. y

c hai bng c th dng li bi nhiu ng hm), v vy khng bao

gm cc i tng ca n trong bng ng hm, ch c d liu

thch hp trnh d tha.

Cc bng truyn thng, c th sau lin kt ti bng chnh s

dng ch mc s nguyn. Cc bng ngoi tr sau c th c chias (v d, nhiu hn trng hp mt ng hm c th c chia s

ging ERO).

Ti ni ny mi lin h lin ct tn ti iu ny phi c ch th

thng minh trong MIB s dng li ch gii.

Cc ct c ngha trong bng MIB th ph thuc vo s phc

tp m cung cp bi v phn cng NMS phi hiu v mi lin h

gia cc ct. T khi NMS phi tm c mi trng thi ca cc NE

NMS phi lu tr d liu NE thng trong c s d liu quan h. Mt



60/84


vn khc l gin c s d liu quan h cng phc tp v

rc ri khi mi lin h gia cc ct phi c sao li. Nu l gin

cui cng th n thng ph thuc vo s sao li d liu MIB, lin ct

MIB ph thuc vo vic to ra mt gin c s d liu phc tp

hn.

Cung cp cc gi tr i tng MIB mc nhCung cp cc gi tr mc nh cho tt c cc i tng bng

MIB l hu dng to s d dng cho lp m cung cp. Ni cch khc,

cuc gi cung cp gi tr c trng cho s cho s ph thuc cc ct

trong bng v da vo gi tr mc nh cho tr. Khi yu cu NMS

n ti lp m cung cp, tt c cc d liu c th vit n l, ti i

tng MIB NE kt hp vi vic kim tra nhanh.Cc gi tr mc nh c th a ra cc i tng MIB bt

ngun t ngoi (i tng cc ct th khng cn thit trong mt hot

ng SNMP a ra), cho v d, mplstunnelIncludeAffinity trong bng -

ng hm MPLS. Ch th ny c s dng khi to ra mt ng hm

trong ngi s dng mun cng bc cc ng tn hiu trong qua

mt vng MPLS. V n s dng dch v thu cho ngi s dng cui

cng trong cch ngn nht, nhiu thi gian, kiu ny ca ng

hm c th khng ph thuc, v i tng mplstunnelIncludeAffinity

trong nhiu trng hp s khng c thit lp. Cung cp gi tr mc

nh cho i tng ny v cc ch th tng t c th gip ngn cn

cc Agent. y c th xut hin nu s tnh c pha thu s

dng mt gi tr khng c hiu lc cho mt column a ra v Agent

c gng gii thch gi tr bng bt k cch no v a ra mt ngoi

l. Nguyn tc ny ch th rng ch c cc ct iu khin bng

nhn cng c thit lp. minh ho iu ny, gi tr cho phpca mplstunnelIncludeAffinity l mt n bt nguyn. Mi mt n bit

miu t mt gi tr m mu giao din, cho v d: 0x00001 cho vng,

0x00010 cho bc, v 0x00100 cho ng. Cc hot ng mng phi

cu hnh cc mu ny trn tt c cc NE ni phn mu s c s

dng. C th cu hnh h tr cho mu bc v ng trn giao

din vo ca chng. Sau mt ng hm c th to ra mt ng

cng bc s dng ch vi giao din vi mu bc v ng bi s thit

lp mplstunnelIncludeAffinity ti 0x00110.



61/84


Mt gi tr mc nh nhn bit c cho mplstunnelIncludeAffinity

(v i tng kt hp ca n) c th l 0 ch th vic khng s

dng i tng MIB ny. T khi gi tr cung cp mc nh c

chn khp vi gi tr mc nh MIB y khng cn cp nht

gi tr trc khi cp nht MIB. S gim bt kch c ca lp m cung cp

MIB mi s c vit ra cho cc gi tr mc nh yu cu ca tt c

cc i tng.

Tp trung MIBS khp vi cc c trng phn t mng

Mt v d tt ca mt tnh nng tp trung l bng ng hm

MPLS. S cha ng hu ht mi quan h ng hm c xc nh

trong bng ny. Cc bng n l ch

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Đồ án chuyển mạch nhãn đa giao thức MPLS