Đồ án chuyển mạch nhãn đa giao thức MPLS
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Transcript of Đồ án chuyển mạch nhãn đa giao thức MPLS
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Mc lc
Mc lc
Thut ng v vit tt ............................................................iv
...........................................................................
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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
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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
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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
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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.
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Li ni u
H Ni ngy 25thng 10 nm 2006
Sinh vinthc hin
Trn ThHng Tr
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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
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n tt nghip i hc Chng 1: Tng quancng ngh MPLS
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
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n tt nghip i hc Chng 1: Tng quancng ngh MPLS
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
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n tt nghip i hc Chng 1: Tng quancng ngh MPLS
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
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n tt nghip i hc Chng 1: Tng quancng ngh MPLS
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:
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n tt nghip i hc Chng 1: Tng quancng ngh MPLS
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).
2. Ch r cc giao thc c tiu chun ho nhm duy
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.
3. Ch r cc giao thc c tiu chun ho nhm duy
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).
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n tt nghip i hc Chng 1: Tng quancng ngh MPLS
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
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n tt nghip i hc Chng 1: Tng quancng ngh MPLS
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.
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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)
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n tt nghip i hc Chng 1: Tng quancng ngh MPLS
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).
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n tt nghip i hc Chng 1: Tng quancng ngh MPLS
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)
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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.
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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:
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n tt nghip i hc Chng 1: Tng quancng ngh MPLS
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
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n tt nghip i hc Chng 1: Tng quancng ngh MPLS
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
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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.
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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.
Trn Th Hng Tr - D2001VT
LSR1
LSR2
LSR3
LER2
LER1
LER3
LER4
Ngun
ch
Lung d liu
Cc yu cu nhn Phn phi nhn
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n tt nghip i hc Chng 1: Tng quancng ngh MPLS
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.
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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.
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n tt nghip i hc Chng 1: Tng quancng ngh MPLS
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.
Trn Th Hng Tr - D2001VT
Routing
UDPTCP
IP Fwd
PHY
LDP CR LDP
LIB MPLS Fwd
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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.
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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
Trn Th Hng Tr - D2001VT
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
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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
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n tt nghip i hc Chng 2: Qun l mngtrong mng vin thng
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.
Trn Th Hng Tr - D2001VT
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
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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
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n tt nghip i hc Chng 2: Qun l mngtrong mng vin thng
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)
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Hnh 2.7: Trao i thng tin gia manager- Agent
Trn Th Hng Tr - D2001VT
SMAE
Managedobjects
Vai tr Agent
CMIPSMAE
Vai tr Manager
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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) .
Trn Th Hng Tr - D2001VT
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
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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.
Trn Th Hng Tr - D2001VT
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
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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:
Trn Th Hng Tr - D2001VT
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
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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)
Trn Th Hng Tr - D2001VT
M hnh iukhin truynhp kiu
quan st
M hnh iukhin truynhp kiu
khc
M hnh iukhin truynhp kiu
khc
H thng con iu khin truy nhp
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n tt nghip i hc Chng 2: Qun l mngtrong mng vin thng
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.
Trn Th Hng Tr - D2001VT
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)
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n tt nghip i hc Chng 2: Qun l mngtrong mng vin thng
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
Trn Th Hng Tr - D2001VT
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)
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n tt nghip i hc Chng 2: Qun l mngtrong mng vin thng
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
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n tt nghip i hc Chng 2: Qun l mngtrong mng vin thng
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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n tt nghip i hc Chng 2: Qun l mngtrong mng vin thng
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
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n tt nghip i hc Chng 2: Qun l mngtrong mng vin thng
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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n tt nghip i hc Chng 2: Qun l mngtrong mng vin thng
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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n tt nghip i hc Chng 2: Qun l mngtrong mng vin thng
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.
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n tt nghip i hc Chng 2: Qun l mngtrong mng vin thng
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
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n tt nghip i hc Chng 2: Qun l mngtrong mng vin thng
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.
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n tt nghip i hc Chng 2: Qun l mngtrong mng vin thng
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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
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n tt nghip i hc Chong 3: ng dng MIB trong qunl mng MPLS
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.
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n tt nghip i hc Chong 3: ng dng MIB trong qunl mng MPLS
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
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n tt nghip i hc Chong 3: ng dng MIB trong qunl mng MPLS
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
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n tt nghip i hc Chong 3: ng dng MIB trong qunl mng MPLS
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.
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n tt nghip i hc Chong 3: ng dng MIB trong qunl mng MPLS
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