Do an ATM-MPLS Cua LuongThiThao

Thit k m hnh mng ATM MPLS

I HC QUC GIA H NI TRng i hc cng ngh

Lng Th Tho

THIt k m hnh mng atm mpls

Kho lun tt nghip i hc h chnh quy

Ngnh: in t - Vin thng

H ni - 2005

Lng Th Tho Trng i hc Cng ngh 1


Li cm nEm xin by t lng knh trng v bit n su sc ti thy gio PGS.TS Nguyn Kim Giao tn tnh ch bo v gip em hon thnh tt kho lun tt nghip ny. ng thi em xin c cm n cc thy c gio trng i hc Cng ngh - i hc Quc Gia H Ni, nhng ngi trang b cho em nhng kin thc gip em hon thnh tt kho lun tt nghip ny.

H Ni, thng 6 nm 2005 Sinh vinLung Th Tho



Tm tt ni dung

Hin nay, mng Inernet truyn thng khng th p ng cc nhu cu ngy cng tng nhanh ca khch hng v khng c bt k c ch iu khin cht lng no, khng h tr tt cht lng dch v v khng cung cp hiu qu mng ring o. Gn y, cng ngh chuyn mch nhn a giao thc (MPLS) c xut s dng ti cc gi tin IP trn cc knh o, MPLS kt hp c cc u im ca chuyn mch gi datagram v chuyn mch knh o v khc phc c cc nhc im trn ca mng truyn thng. Do vy, trong ti lun vn ny, em mun gii thiu v cng ngh MPLS. Tuy nhin tn dng c s h tng ca cng ngh ATM hin ti - cng ngh tin cy c kim chng qua thc t v tng bc tin ti mng MPLS hon ton, lun vn tp trung nghin cu v cc gii php thit k mng ATM MPLS. c bit bi bo co nghin cu thit k m hnh m phng mng ATM MPLS c th ng dng trong nhng iu kin Vit Nam, cng nh phc v cho o to ti b mn Vin Thng - trng i hc Cng Ngh HQGHN.



MC LC

Trang Li m u ................................................................................................................1 Chng 1. Gii thiu v cng ngh MPLS .................................................... 3 1.1 Gii thiu .........................................................................................................3 1.1.1 Khi nim MPLS .....................................................................................4 1.1.2 S ra i ca MPLS .................................................................................4 1.2 Tnh hnh trin khai v qu trnh chun ho v MPLS .............................7 1.2.1 Tnh hnh trin khai MPLS ......................................................................7 1.2.2 Qu trnh chun ho v MPLS .................................................................8 1.3 Cc u im v ng dng ca MPLS ............................................................9 1.3.1 u im ...................................................................................................9 1.3.2 ng dng ................................................................................................10 1.4 Tm tt chng .............................................................................................11

CHNG 2. Cc thnh phn v hot ng ca mng MPLS..122.1 Cc khi nim c bn ca MPLS ....................................................................12 2.2 Cc thnh phn c bn ca MPLS ..................................................................15 2.3 Cc giao thc c bn ca MPLS .....................................................................16 2.3.1 Giao thc phn b nhn LDP ...........................................................16 2.3.2 Giao thc CR-LDP ..............................................................................17 2.3.3 Giao thc RSVP ..................................................................................17 2.3.4 Giao thc MPLS-BGP .........................................................................17 2.3.5 Kin trc h thng giao thc MPLS ...................................................17 2.4 Hot ng ca MPLS ......................................................................................19 2.4.1 Chuyn mch nhn .............................................................................19 2.4.2 hnh mng MPLS ..........................................................................20 2.4.3 Cc bc hot ng ca MPLS ...........................................................20 2.4.4 Cc ng hm trong MPLS ...............................................................23 2.5 Trin khai ng dng cng ngh MPLS ti Vit Nam .....................................24 2.5.1 Kh nng ng dng ca MPLS ...........................................................25 2.5.2 Mt s nguyn tc khi trin khai mng NGN......................................25 2.5.3 M hnh mng MPLS ..........................................................................26

2.6 Tm tt chng ..............................................................................................27

CHNG 3: Thit k mng ATM MPLS ...................................................... 283.1 Gii thiu ........................................................................................................28 3.1.1 M hnh chc nng mng NGN ..........................................................29 3.1.2 Chuyn mch th v thut ng ............................................................30


Thit k m hnh mng ATM MPLS 3.1.3 Cc cu trc chung ca MPLs .............................................................31 3.1.4 MPLS v cc kt hp IP trn ATM khc ............................................32 3.1.5 Cc bc thit k mng ATM MPLS ................................................33 Chn thit b MPLS .......................................................................................34 3.2.1 Cu trc mng MPLS .........................................................................34 3.2.2 Chn thit b MPLS Cisco .................................................................38 3.2.3 IP+ATM .............................................................................................45 Thit k mng ATM MPLS ...........................................................................48 3.3.1 Cu trc cc im truy nhp dch v PoP ...........................................48 3.3.2 Xc nh cc ng lin kt ca mng ATM MPLS.............................53 3.3.3 nh tuyn IP trong mng ATM MPLS ................................................63 3.3.4 Xc nh khng gian knh o VC nhn MPLS ..................................66 3.3.5 Thit k mng lin tc ...........................................................................80 ng dng m hnh ATM MPLS trong gii php ca Nortel ..........................80 Tm tt chng ..............................................................................................82 Cc tiu ch xy dng mng vin thng ng dng trong o to ............... ..83 Xy dng m hnh mng vin thng ng dng trong o to .......................84 Nhn xt ............. ...........................................................................................89 Tm tt chng .. ...........................................................................................90

3.2

3.3

3.4 3.5 4.1 4.2 4.3 4.5

CHNG 4. Trin khai ng dng ca mng ATM MPLS ....................... . 83

KT LUN .................................................................................................................91 Ti liu tham kho ..........................................................................................92



THUT NG VIT TTVit ttATM ASBP BGP CLNP CRLDP Border Gateway Protocol Connectionless Network Protocol Constraint-Based RoutingLDP

Ting AnhAysnchronous Transfer Mode

Ting vitPhng thc truyn tin khng ng b B nh tuyn ng bin h thng t tr BGP Giao thc nh tuyn ging nh giao thc cng bin Giao thc mng khng kt ni Giao thc phn phi nhn nh tuyn da trn rng buc

CSR DLCI DWDM FEC FIB GMPLS IEIF IGP

Cell Switching Router Data Link Connection Identifier Dense Wavelength Divion Multiplexing Forwarding Equivalence Class Forwarding Information Base Generalized Multi Protocol Label Switching Internation Engineering Task Force Interior Gateway Protocol

B nh tuyn chuyn mch t bo Nhn dng kt ni lp lin kt d liu Ghp knh phn chia theo bc sng mt cao Lp chuyn tip tng ng C s d liu chuyn tip trong b nh tuyn Chuyn mch nhn a giao thc tng qut T chc tiu chun k thut Quc t Internet Giao thc nh tuyn trong min



IMA IP IS-IS IS-ISTE LAN LDP LER LFIB LIB LMP LSC LSP LSR MPLS NGN OSPF Label Switched Path Label Switching Router Multi Protocol Label Switching Next Generation Network Open Shortest Path First Internet Protocol Intermedia System to Intermedia System Intermedia System to Intermedia System Traffic Engineer Local Area Network Label Distribution Protocol Label Edge Router Label Forwarding Information Base Label Information Base Link Management Protocol

Hp knh o trn ATM Giao thc Internet Giao thc nh tuyn mng trung gian ti mng trung gian Giao thc IS-IS c k tht lu lng

Mng cc b Giao thc phn phi nhn B nh tuyn bin nhn C s thng tin chuyn tip nhn C s thng tin nhn Giao thc qun l knh B iu khin chuyn mch nhn ng chuyn mch nhn B nh tuyn chuyn mch nhn Chuyn mch nhn a giao thc Mng th h sau Giao thc nh tuyn m rng theo phng thc u tin tuyn ng ngn nht u ni ghp quang Giao din nt nt ring

OXC PNNI

Optical Cross-Connect Private Node to Node Interface



PPP QoS RIP RSVP SDH SONET TCP TDP TE UDP VC VCI VP VPI VPN WAN

Point to Point Protocol Quanlity of Service Realtime Internet Protocol Resource Reservation Protocol Synchronous Digital Hierachy Synchronous Optical Network Transport Control Protocol Tag Distribution Protocol Traffic Engineering User Data Protocol Virtual connection Virtual Circuit Identifier Virtual Path Virtual Path Identifier Virtual Private Network Wide Area Network

Giao thc im im Cht lng dch v Giao thc bo hiu IP thi gian thc Giao thc dnh trc ti nguyn Phn cp truyn dn s ng b Mng quang ng b Giao thc iu khin truyn ti Giao thc phn b th iu khin lu lng Giao thc d liu ngi s dng Kt ni o Nhn dng ng o trong t bo Knh o Nhn dng knh o trong t bo Mng ring o Mng din rng



Li m uNn tng cho x hi thng tin chnh l s pht trin cao ca cc dch v vin thng. Mm do, linh hot, v gn gi vi ngi s dng l mc tiu cn hng ti. Vi nm qua, Internet ang ngy cng pht trin vi cc ng dng mi trong thng mi v th trng ngi tiu dng. Cng vi cc dch v truyn thng hin nay c cung cp qua Internet th cc dch v thoi v a phng tin ang c pht trin v s dng. Tuy nhin, tc v di thng ca cc dch v v ng dng ny vt qu ti nguyn h tng Internet hin nay. Chnh nhng iu gy mt p lc cho mng vin thng hin thi, phi m bo truyn ti thng tin tc cao vi gi thnh h. gc khc s ra i ca nhng dch v mi ny i hi phi c cng ngh thc thi tin tin. u im ni bt ca giao thc nh tuyn TCP/IP l kh nng nh tuyn v truyn gi tin mt cch ht sc mm do linh hot v rng khp ton cu. Nhng IP khng m bo cht lng dch v, tc truyn tin theo yu cu, trong khi cng ngh ATM c th mnh u vit v tc truyn tin cao, m bo thi gian thc v cht lng dch v theo yu cu nh trc. S kt hp IP vi ATM c th l gii php k vng cho mng vin thng tng lai - mng th h sau NGN. Gn y, cng ngh chuyn mch nhn a giao thc (MPLS) c xut ti cc gi tin trn cc knh o v khc phc c cc vn m mng ngy nay ang phi i mt, l tc , kh nng m rng cp mng, qun l cht lng, qun l bng thng cho mng IP th h sau - da trn mng ng trc v c th hot ng vi cc mng Frame Relay v ch truyn ti khng ng b (ATM) hin nay p ng cc nhu cu dch v ca ngi s dng mng. Ngy nay, nhng xu hng pht trin cng ngh v ang tip cn nhau, an xen ln nhau cho php mng li tha mn tt hn cc nhu cu ca khch hng trong tng lai. Th trng vin thng trn th gii ang ng trong xu th cnh tranh v pht trin hng ti mng vin thng hi t ton cu to ra kh nng kt ni a dch v trn phm vi ton th gii. Do vy, p ng c cc nhu cu , s ra i ca MPLS l tt yu. Tuy nhin, hin ti vn cha r rng liu MPLS c p ng c hay khng i hi v cht lng dch v - QoS m ATM khng nh v tr ca mnh. ATM cho n gi vn l cng ngh duy nht c kim nghim v thnh cng trong vic tch


Thit k m hnh mng ATM MPLS hp d liu, thoi, v video trn cng mt mng. Hin ti th mt gii php kt hp an ton kh thi l chy c ATM v MPLS trn mng ng trc. Vi ngha cng vic nghin cu tm hiu v nh gi cc gii php thit k mng ATM MPLS c tin hnh trong lun vn ny l rt cn thit, c bit khi xu th mng NGN (mng th h sau) hi t ton cu to ra kh nng kt ni a dch v trn phm vi ton th gii. Vi ton b ni dung trnh by trong lun vn ny, ti mong mun c tip tc nghin cu v vn ny nhm tham gia v trao i vn thit k trong lnh vc mng th h sau cn rt rng ln v hp dn. Mc ch ca ti lun vn l nghin cu tm hiu cng ngh MPLS tin ti thit k mng ATM MPLS c th a vo ng dng trong nhng iu kin c th ti Vit Nam v cng nh phc v cho o to v cng ngh mng vin thng ti trng i hc Cng ngh - HQGHN. Vi mc tiu ni dung ca lun vn gm cc vn sau: Chng 1: Gii thiu tng quan v cng ngh chuyn mch nhn a giao thc (MPLS). Chng 2: Gii thiu cc thnh phn v hot ng ca mng MPLS. Chng 3: Thit k mng ATM MPLS. Chng 4: Trin khai ng dng ca mng ATM MPLS trong o to .



Chng 1: Gii thiu Cng ngh MPLS1.1 Gii thiu

Trong nhng nm gn y, mng Internet pht trin nhanh v tr nn rt ph bin, Internet m ra mt phng tin thng tin rt hiu qu v tin li phc v cho gio dc, thng mi, gii tr, thng tin gia cc cng ng .v.v Hin nay ngy cng pht trin cc ng dng mi c trong thng mi v th trng ngi tiu dng. Thm vo cc dch v a phng tin ang c pht trin v trin khai thc y nhu cu v tc v di bng tng nhanh. Cng vi n s lng ngi s dng ngy cng tng, cht lng ngi s dng phi c nng cao. Tuy nhin, ti nguyn h tng Internet hin nay khng p ng c cc nhu cu . S ra i ca chuyn mch nhn a giao thc MPLS l tt yu khi nhu cu v tc pht trin rt nhanh ca mng Internet yu cu phi c mt giao thc mi m bo cht lng dch v theo yu cu ng thi phi n gin v tc x l phi rt cao. Tht vy, MPLS cung cp mt nn tng cng ngh mi cho qu trnh to ra cc mng a ngi dng, a dch v vi hiu nng cao hn, kh nng m rng mng ln, nhiu chc nng c ci tin v p ng c nhiu yu cu v cht lng dch v. Chuyn mch nhn l yu t quan trng nht cho qu trnh m rng Internet, n cung cp nhng ng dng quan trng trong x l chuyn tip gi bng cch n gin ha qu trnh x l, hn ch vic to ra cc bn sao mo u ti mi bc trong ng dn, v to ra mt mi trng c th h tr cho iu khin cht lng dch v. Pht trin ca MPLS cho php tch hp IP v ATM, h r hi t dch v v cung cp nhng c hi mi cho iu khin lu lng v mng ring o. Hiu nng x l gi c th c ci tin bng cch thm nhn c kch thc c nh vo cc gi. iu khin cht lng dch c th c cung cp d dng hn v c th xy dng cc mng cng cng rt ln. MPLS l mt k thut mi c mong i s pht trin ph bin trn phm vi rng c cc mng IP ring v cng cng, m ng cho vic hi t cc dch v mng, video v thoi. Tm li, MPLS s ng mt vai tr quan trng trong vic nh tuyn, chuyn mch v chuyn tip cc gi qua mng th h sau cng nh gii quyt cc vn lin quan ti kh nng m rng cp v c th hot ng vi cc mng Frame relay v ATM hin nay p ng cc nhu cu dch v ca ngi s dng mng.



1.1.1 Khi nim cng ngh chuyn mch nhn a giao thc MPLSChuyn mch nhn a giao thc - MPLS (MultiProtocol Label Switching) l mt bin php linh hot gii quyt nhng vn gp nhiu kh khn trong mng hin nay nh: tc , quy m, cht lng dch v (QoS), qun tr v k thut lu lng. MPLS th hin mt gii php thng minh p ng nhng i hi dch v v qun l di thng cho mng IP th h sau - da trn mng ng trc. MPLS gii quyt nhng vn lin quan n tnh quy m v nh tuyn (da trn QoS v dng cht lng dch v) v c th tn ti trn mng ATM (phng thc truyn khng ng b - Asynchronous Tranfer Mode) v mng Frame-relay ang tn ti. MPLS thc hin mt s chc nng sau: Xc nh c cu qun l nhiu mc khc nhau ca cc lung lu lng, nh cc lung gia cc c cu, phn cng khc nhau hoc thm ch cc lung gia nhng ng dng khc nhau. Duy tr s c lp ca cc giao thc lp 2 v lp 3. Cung cp phng php nh x a ch IP vi cc nhn n gin, c di c nh c s dng bi cc cng ngh chuyn tip gi v chuyn mch gi khc nhau. Giao din vi cc giao thc nh tuyn hin c nh giao thc t trc ti nguyn (RSVP) v giao thc m rng theo phng thc u tin tuyn ng ngn nht (OSPF). H tr IP, ATM v giao thc lp 2 Frame-relay.

1.1.2 S ra i ca MPLSMPLS l kt hp mt cch hon ho cc u im ca cng ngh IP v ATM a) Cng ngh IP IP (Giao thc Internet Internet Protocol) l thnh phn chnh ca kin trc mng Internet. IP nh ngha c cu nh s, c cu chuyn tin, c cu nh tuyn v cc chc nng iu khin mc thp (Giao thc bn tin iu khin Internet - ICMP). Gi tin IP gm a ch ca bn nhn; a ch l mt s duy nht trong ton mng v mang y thng tin cn cho vic chuyn gi tin ti ch. C cu nh tuyn c nhim v tnh ton ng i ti cc nt trong mng. Do vy, c cu nh tuyn phi c cp nht cc thng tin v hnh mng,


Thit k m hnh mng ATM MPLS thng tin v nguyn tc chuyn tin (nh trong Giao thc nh tuyn bin min - BGP) v n phi c kh nng hot ng trong mi trng mng gm nhiu nt. Kt qu tnh ton ca c cu nh tuyn c lu trong cc bng chuyn tin cha thng tin v chng tip theo c th gi gi tin ti hng ch. Da trn cc bng chuyn tin, c cu chuyn tin chuyn mch cc gi IP hng ti ch. Phng thc chuyn tin truyn thng l theo tng chng mt. cch ny, mi nt mng phi tnh ton bng chuyn tin mt cch c lp. Do vy, phng thc ny yu cu kt qu tnh ton ca phn nh tuyn ti tt c cc nt phi nht qun vi nhau. S khng thng nht ca kt qu ny ng ngha vi vic mt gi tin. Kiu chuyn tin theo tng chng hn ch kh nng ca mng. V d, vi phng thc ny, nu cc gi tin chuyn ti cng mt a ch m i qua cng mt nt th chng s c truyn qua cng mt tuyn ti im ch. iu ny khin mng khng th thc hin mt s chc nng khc nh nh tuyn theo ch, theo loi hnh dch v .v.v Tuy nhin, bn cnh , phng thc nh tuyn v chuyn tin ny nng cao tin cy cng nh kh nng m rng ca mng. Giao thc nh tuyn ng cho php mng phn ng li vi s c bng vic thay i tuyn khi b nh tuyn bit c s thay i v hnh mng thng qua vic cp nht thng tin v trng thi kt ni. Vi cc phng thc nh nh tuyn lin min khng phn cp (Classless InterDomain Routing - CIDR), kch thc ca bng chuyn tin c duy tr mc chp nhn c v vic tnh ton nh tuyn u do cc nt t thc hin, mng c th c m rng m khng cn thc hin bt k mt thay i no. Tm li, IP l mt giao thc chuyn mch gi c tin cy v kh nng m rng cao. Nhng vic iu khin lu lng rt kh thc hin do phng thc nh tuyn theo tng chng.Ngoi ra, IP khng h tr cht lng dch v. b) Cng ngh ATM Cng ngh ATM (Aysnchronous Transfer Mode phng thc truyn tin khng ng b) l mt k thut truyn tin tc cao.ATM nhn thng tin nhiu dng khc nhau nh thoi, s liu, video v ct ra thnh nhiu phn nh gi l t bo. Cc t bo ny, sau , c truyn qua cc kt ni o VC (Virtual connection). V ATM c th h tr thoi, s liu v video vi cht lng dch v trn nhiu cng ngh bng rng khc nhau, n c coi l cng ngh chuyn mch hng u v thu ht c nhiu quan tm.


Thit k m hnh mng ATM MPLS ATM khc vi nh tuyn IP mt s im. N l cng ngh chuyn mch hng kt ni. Kt ni t im u n im cui phi c thit lp trc khi thng tin c gi i. ATM yu cu kt ni phi c thit lp bng nhn cng hoc thit lp mt cch t ng thng qua bo hiu. Mt im khc nhau na l ATM khng thc hin nh tuyn ti cc nt trung gian. Tuyn kt ni xuyn sut c xc nh trc khi trao i d liu v c gi c nh trong thi gian kt ni. Trong qu trnh thit lp kt ni, cc tng i ATM trung gian cp cho kt ni mt nhn. Vic ny thc hin hai iu: dnh cho kt ni mt s ti nguyn v xy dng bng chuyn t bo ti mi tng i. Bng chuyn t bo ny c tnh cc b v ch cha thng tin v cc kt ni ang hot ng i qua tng i. iu ny khc vi thng tin v ton mng cha trong bng chuyn tin ca b nh tuyn dng IP. Qu trnh chuyn t bo qua tng i ATM cng tng t nh vic chuyn gi tin qua b nh tuyn. Tuy nhin, ATM c th chuyn mch nhanh hn v nhn gn trn cc t bo c kch thc c nh (nh hn ca IP), kch thc ca bng nh tuyn nh hn nhiu so vi b nh tuyn IP, v vic ny c thc hin trn cc thit b phn cng chuyn dng. Do vy, thng lng ca tng i ATM thng ln hn thng lng ca b nh tuyn IP truyn thng. Ni cch khc, cng ngh ATM l mt k thut truyn tin tc cao, m bo thi gian thc v cht lng dch v theo yu cu nh trc. c) Cng ngh MPL S - Kt hp gia cng ngh IP v ATM u im ni bt ca giao thc nh tuyn TCP/IP l kh nng nh tuyn v truyn gi tin mt cch ht sc mm do linh hot v rng khp ton cu. Nhng IP khng m bo cht lng dch v, tc truyn tin theo yu cu, trong khi cng ngh ATM c th mnh u vit v tc truyn tin cao, m bo thi gian thc v cht lng dch v theo yu cu nh trc. S kt hp IP vi ATM c th l gii php k vng cho mng vin thng tng lai - mng th h sau NGN. Chuyn mch nhn a giao thc - MPLS p ng c nhu cu . MPLS kt hp cc u im ca cng ngh IP v ATM to ra mt gii php linh hot cho vic gii quyt cc vn m cc mng ngy nay ang phi i mt, l tc , kh nng m rng cp mng, qun l cht lng dch v (QoS) v k thut lu lng. Tht vy, cng ngh Chuyn mch nhn a giao thc MPLS l kt qu pht trin ca nhiu cng ngh chuyn mch IP s dng c ch hon i nhn nh ca


Thit k m hnh mng ATM MPLS ATM tng tc truyn gi tin m khng cn thay i cc giao thc nh tuyn ca IP. T tng khi a ra MPLS l: nh tuyn ti bin, chuyn mch li. Trong cc mng MPLS, cc gi c gn nhn ti bin ca mng v chng c nh tuyn xuyn qua mng da trn cc nhn n gin. Phng php ny cho php nh tuyn r rng v i x phn lit cc gi trong khi vn gi c cc b nh tuyn li n gin. C th ni MPLS l mt cng ngh chuyn mch IP c nhiu trin vng.Vi tnh cht c cu nh tuyn ca mnh, MPLS c kh nng nng cao cht lng dch v ca mng IP truyn thng. Bn cnh , thng tin lu lng ca mng s c ci thin r rt.

1.2 Tnh hnh trin khai cng ngh v qu trnh chun ho v MPLS1.2.1 Tnh hnh trin khai cng ngh MPLSBIG PIPE nh khai thc mng trc IP ca Canada la chn Cisco Systems l nh cung cp thit b cho mng trc IP OC-192 vo thng 10 nm 2001- cc b nh tuyn ca Cisco trong mng trc ny s cho php BIG PIPE cung cp bng thng OC192. Cc b nh tuyn 12410 v 12416 ca Cisco s cho php nh cung cp dch v ny trin khai cc dch v IP th h sau nh MPLS-VPN, IP QoS v Voice over IP (VOIP). Juniper Network v Ericsson Communication thng bo rng th h Internet Router trc mi (serie M) c trin khai trong mng trc mi ca TelstraSaturn. TelstraSaturn l cng ty u tin ti New Zealand trin khai mng bng tn ln nht cung cp c IP v thoi. Cc b nh tuyn M160 v M20 c trin khai trong mng trc ti lu lng qua MPLS. y l mng thng mi u tin trin khai y STM-16 (2.5 Gb/s) ti New Zealand. Thng 10 Alcatel thng bo k hp ng cung cp thit b bng rng cho Deatsche Telecom Group. Cc sn phm ca Alcatel bao gm: thit b chuyn mch nh tuyn (RSP) 7670 cho mng chuyn i s liu ATM ca quc ni ti c. Thit b ny s cho php Deatsche Telecom m rng mng a dch v ca h t 12.8 Gb/s ln 450 Gb/s tho mn nhu cu trong mng thc. Thit b ny c kh nng chuyn mch MPLs trn ATM.


Thit k m hnh mng ATM MPLS NTT America thng bo trin khai dch v Arestar Global IP-VPN n tt c cc doanh nghip ti M. Dch v Arestar IP-VPN cung cp gii php hon chnh bao gm nhiu cng ngh IP VPN, MPLS. China Telecom la chn Nortelworks trong 2 hp ng tr ga 12 triu USD nng cp mng ATM a dch v ti tnh Jiasngu v Shandong vo thng 10 nm 2001. Hai mng ny cho php China Telecom cung cp dch v ATM tin tin, duy nht. China Telecom c k hoch thay th cc thit b chuyn mch ng trc hin ti bng gii php ca Nortel Network. Cc thit b bao gm: Passport 15000, Passport 7480 MS. Cc thit b ny cung cp cc dch v ATM, Frame Relay, Chuyn mch v nh tuyn IP, MPLS Riverstone Network trin khai mng cho hai nh cung cp Chu u l Telenet - nh cung cp dch v B v Neosnetwork - nh khai thc ca U.K. Nh khai thc ny trin khai mng MPLS u tin ti U.K vi Router loi RS. Neosnetworks chn RS 8600 multi-service router v RS 3000 metro access router cung cp dch v Ethernet nh mt phn trong mng truyn s liu ton quc ca U.K. Telenet la chn Reverstone l nh cung cp cc router cho mng ng trc IP trong mng truyn s liu v mng cp ca mnh. Telenet s dng Reverstone RS 8600 multiservice mto routers. C hai d n ny u c trin khai cui nm 2001. Alcatel thng bo thng 10 nm 2001 sn phm Alcatel 7670 RSP c la chn m rng mng ATM ton quc ca Belgacom. Sn phm ny cho php Belgacom m rng mng ATM a dch v hin ti, Belgacom s trin khai thm cc tng i truy nhp Alcatel 7470 MSP ti lu lng IP v cc dch v DSL. Trong nm 2001, Belgacom tng s lng khch hng truy nhp Internet ln 100.000 trong thng 7 v ln ti 200.000 vo cui nm. Thit b a giao thc Alcatel 7670 RSP l thit b MPLS cho php tch hp ATM v MPLS/IP trong mt thit b duy nht.

1.2.2 Qu trnh chun ha MPLSi vi cc cng ngh chuyn mch mi, vic tiu chun ho l mt kha cnh quan trng quyt nh kh nng chim lnh th trng nhanh chng ca cng ngh . Cc tiu chun lin quan n IP v ATM c xy dng v hon thin trong mt thi gian tng i di. Cc tiu chun v MPLS ch yu c IETF pht trin (cc tiu chun RFC Request for Comment) hin ang c hon thin v thc hin theo mt qu trnh nh sau:


Thit k m hnh mng ATM MPLS Vo u nm 1997, hin chng MPLS c thng qua. Vo thng 4 nm 1997, nhm lm vic MPLS tin hnh cuc hp u tin. Vo thng 11 nm 1997, ti liu MPLS c ban hnh. Vo thng 7 nm 1998, ti liu cu trc MPLS c ban hnh. Trong thng 8 v thng 9 nm 1998, 10 ti liu Internet b sung c ban hnh, bao gm giao thc phn phi nhn MPLS (MPLS Label Distribution Protocol MPLS LDP), m ha nh du (Mark Encoding), cc ng dng ATM,v.v MPLS hnh thnh v cn bn. IETF hon thin cc tiu chun MPLS v a ra cc ti liu RFC trong nm 1999. Qu trnh chun ho MPLS cn do ITU-T xy dng v pht trin. Nh vy, c th thy rng MPLS pht trin nhanh chng v hiu qu. iu ny cng chng minh nhng yu cu cp bch trong cng nghip cho mt cng ngh mi. Hu ht cc tiu chun MPLS hin ti c ban hnh di dng RFC.

1.3 Mt s u im v ng dng ca cng ngh MPLS1.3.1 Cc u im ca MPLSMc d thc t rng MPLS ban u c pht trin vi mc ch gii quyt vic chuyn tip gi tin, nhng li im chnh ca MPLS trong mi trng mng hin ti li t kh nng iu khin lu lng ca n. Mt s li ch ca MPLS: H tr mm do cho tt c cc dch v (hin ti v sp ti) trn mt mng n. n gin ha hnh v cu hnh mng khi so vi gii php IP qua ATM.

H tr tt c cc cng c iu khin lu lng mnh m bao gm c nh tuyn lin tip v chuyn mch bo v. H tr a kt ni v a giao thc: thit b chuyn tip chuyn mch nhn c th c dng khi thc hin chuyn mch nhn vi IP cng tt nh vi IPX. Chuyn mch nhn cng c th vn hnh o trn bt k giao thc lp lin kt d liu. Kh nng m rng: chuyn mch nhn cng c u im v tc gia chc nng iu khin v chuyn tip. Mi phn c th pht trin khng cn n cc phn khc, to s pht trin mng d dng hn, gi thnh thp hn v li t hn.



H tr cho tt c cc loi lu lng: mt u im khc ca chuyn mchnhn l n c th h tr cho tt c cc loi chuyn tip unicast, loi dch v unicast v cc gi multicast.

1.3.2 Cc ng dng ca MPLSMng MPLS c nhiu ng dng trong c 3 ng dng chnh v thng thng 2 trong c 3 kh nng c s dng ng thi: Tch hp IP+ATM - Do chuyn mch nhn c th thc hin c bi cc chuyn mch ATM, MPLS l mt phng php tch hp cc dch v IP trc tip trn chuyn mch ATM. S tch hp ny cn phi t nh tuyn IP v phn mm LDP trc tip trn chuyn mch ATM. Do tch hp hon ton IP trn chuyn mch ATM, MPLS cho php chuyn mch ATM h tr ti u cc dch v IP nh IP a hng (multicast), lp dch v IP, RSVP(Resource Reservation Protocol Giao thc h tr ti nguy n) v mng ring o. Dch v mng ring o IP (VPN) - VPN thit lp c s h tng cho mng intranet v extranet, l cc mng IP m cc cng ty kinh doanh s thit lp trn c s ton b cu trc kinh doanh ca h. Dch v VPN l dch v mng Intranet v Extranet m cc mng c cung cp bi nh cung cp dch v n nhiu t chc khch hng. MPLS kt hp vi giao thc cng bin (BGP) cho php mt nh cung cp mng h tr hng nghn VPN ca khch hng . Nh vy, mng MPLS cng vi BGP to ra cch thc cung cp dch v VPN trn c ATM v cc thit b da trn gi tin rt linh hot, d m rng quy m v d qun l. Thm ch trn cc mng ca nh cung cp kh nh, kh nng linh hot v d qun l ca cc dch v MPLS+BGP VPN l u im ch yu. iu khin lu lng v nh tuyn IP r rng - vn quan trng trong cc mng IP lin tc l thiu kh nng iu khin linh hot cc lung lu lng IP s dng hiu qa di thng mng c sn. Do vy, thiu ht ny lin quan n kh nng gi cc lung c chn xung cc ng c chn v d nh chn cc ng trung k c bo m cho cc lp dch v ring. MPLS s dng cc ng chuyn mch nhn (LSPs), chnh l mt dng ca lightweight VC m c th c thit lp trn c ATM v thit b da trn gi tin. Kh nng iu khin lu lng IP ca MPLS s dng thit lp c bit cc LSP iu khin mt cch linh hot cc lung lu lng IP.



1.4 Tm tt chngNh vy, chng 1 Gii thiu tng quan v cng ngh chuyn mch nhn a giao thc (MPLS). Trong chng ny trnh by v khi nim v MPLS, s ra i ca MPLS da trn kt hp hon ho cc u im ca cng ngh IP, cng ngh ATM. Do cc nguyn l c bn ca cc cng ngh IP, ATM, MPLS cng c tm hiu. Ngoi ra, tnh hnh trin khai cng ngh v qu trnh chun ho v MPLS, cng nh cc u im v ng dng chnh ca MPLS cng c cp n.



Chng 2: cc thnh phn v hot ng ca mng mpls2.1 Cc khi nim c bn ca mng MPLSMt vi khi nim c bn cn phi hiu r trc khi m t hot ng ca mng MPLS. a) Lp chuyn tip tng dng (Forward Equivalence Class - FEC) Lp chuyn tip tng ng-FEC l mt khi nim c dng ch mt lp cc gi tin c u tin nh nhau trong qu trnh vn chuyn. Tt c cc gi trong mt nhm c i x nh nhau trn ng ti ch. Khc vi IP thng thng, trong MPLS, cc gi tin ring bit c gn vo cc FEC ring ngay sau khi chng vo mng. Cc FEC da trn yu cu dch v cho vic thit lp cc gi tin hay n gin cho mt tin a ch. b) Nhn v gn nhn Nhn trong dng n gin nht xc nh ng i m gi c th truyn qua. Nhn c mang hay c ng gi trong tiu lp 2 cng vi gi tin. B nh tuyn kim tra cc gi qua ni dung nhn xc nh cc bc chuyn tip k tip. Khi gi tin c gn nhn, cc chng ng cn li ca gi tin thng qua mng ng trc da trn chuyn mch nhn. Gi tr ca nhn ch c ngha cc b ngha l chng ch lin quan n cc bc chuyn tip gia cc LSR. Nhn c gn vo gi tin khi gi tin c sp xp bi cc FEC mi hay FEC ang tn ti. Gi tr nhn ph thuc vo phng tin m gi tin c ng gi. i vi mng Frame Relay s dng gi tr nhn dng kt ni lp lin kt d liu DLCI ( Data Link Connection Identifier), ATM s dng trng nhn dng ng o trong t bo/ trng nhn dng knh o trong t bo (Virtual Path Identifier/ Virtual Circuit Identifier - VPI/VCI). Sau gi c chuyn tip da trn gi tr ca chng. Vic gn nhn da trn nhng tiu ch sau: nh tuyn unicast ch K thut lu lng Multicast Mng ring o (Virtual Private Networks - VPN) Cht lng dch v (Quality of Service - QoS)


Thit k m hnh mng ATM MPLS nh dng chung ca nhn c gii thch trong hnh 1. Nhn c th hin r trong tiu ca cc lp lin kt (VPI/VCI ca ATM trong hnh 2 v DLCI ca Frame Relay trong hnh 3) hoc trong lp d liu shim (gia tiu lp lin kt d liu lp 2 v tiu lp mng lp 3 nh trong hnh 4)

Hnh 1: nh dng chung cu nhn MPLS Trong hnh 1, phn SHIM MPLS: Label (20 bit): cha ga tr nhn Exp.bits: CoS (3 bit)- cht lng dch v BS (1 bit) bie-stack: xc nh nhn cui cng trong ngn xp TTL (8bit)- time to live: trng nh thi

Hnh 2: Lp lin kt d liu l ATM


Thit k m hnh mng ATM MPLS Hnh 3: Lp lin kt d liu l Frame Relay

Hnh 4: Nhn trong shim - gia lp 2 v lp 3 c) To nhn To nhn da trn cc phng php sau: Topo: nh giao thc nh tuyn thng thng (OSPF v BGP) Yu cu: iu khin lu lng da trn yu cu Lu lng: nhn gi tin phn phi v gn nhn d) Ngn xp nhn l mt tp hp c th t cc nhn gn theo gi truyn ti thng tin v FEC m gi nm trong v v cc LSP tng ng gi s i qua. Ngn xp nhn cho php MPLS h tr nh tuyn phn cp. Mi mc trong ngn xp nhn gn lin vi mc phn cp no . iu ny to iu kin thun li cho ch hot ng ng hm trong MPLS. e) Bng chuyn tip chuyn tip chuyn mch nhn L bng chuyn tip nhn c cha thng tin v nhn vo, nhn ra, giao din vo, giao din ra. f) C s d liu nhn (Label Information Base - LIB) C s d liu nhn (Label Information Base - LIB) l bng cha cc gi tr nhn/ FEC c gn vo cng nh thng tin v ng gi d liu truyn ti mi LSR xc nh cch thc mt gi tin c chuyn tip. g) ng chuyn mch nhn (Label Switched path - LSP) Trong MPLS, vic truyn d liu thc hin theo cc ng chuyn mch nhn (Label Switched path - LSP). Cc ng chuyn mch nhn cha mt chui cc nhn ti tt c cc nt dc theo tuyn t ngun ti ch. LSP c thit lp trc khi truyn d liu hoc trong khi xc nh lung d liu no . Cc nhn c phn phi bng vic s dng giao thc phn phi nhn (Label Distribution Protocol - LDP) hoc giao thc ginh trc ti nguyn (Resource Reservation Protocol - RSVP) trn cc giao


Thit k m hnh mng ATM MPLS thc nh tuyn ging nh giao thc cng bin (Border Gateway Protocol - BGP) v giao thc nh tuyn m rng theo phng thc u tin tuyn ng ngn nht (Open Shortest Path First - OSPF). Mi gi d liu c ng gi li v mang cc nhn trong sut thi gian di chuyn t ngun ti ch. Chuyn mch d liu tc cao hon ton c th thc hin da theo phng php ny, v cc nhn c di c nh c chn vo phn u ca gi tin hoc t bo v c th c s dng bi phn cng chuyn mch nhanh cc gi gia cc lin kt. h) C cu bo hiu Yu cu nhn - S dng c cu ny, mt LSR yu cu mt nhn t dng xung ln cn nn n c th lin kt n FEC xc nh. C cu ny c th c dng truyn n cc LSR tip theo cho n LER lira. p ng nhn - p ng mt yu cu nhn, LSR lung xung s gi mt nhn n cc b khi ng lung ln s dng c cu nh x nhn.

Hnh 5: C cu bo hiu

2.2 Cc thnh phn c bn ca mng MPLSa) B nh tuyn bin nhn (Label Edge Router - LER) L thit b hot ng ti bin ca mng truy nhp v mng MPLS. LER h tr nhiu cng kt ni t nhng mng khc (nh Frame Relay, ATM v Ethernet) v chuyn tip cc gi lu lng ny ti mng MPLS sau khi thit lp ng chuyn mch nhn LSP s dng giao thc bo hiu nhn ti li vo v phn b lu lng quay tr li mng truy cp ti li ra. LER c vai tr rt quan trng trong vic gn v tch nhn khi lu lng i vo hoc i ra trong mng MPLS. b) B nh tuyn chuyn mch nhn (Label Switching Router - LSR) LSR l b nh tuyn tc cao trong mng li MPLS tham gia vo vic thit lp ng chuyn mch nhn LSP s dng cc giao thc bo hiu nhn thch hp v


Thit k m hnh mng ATM MPLS chuyn mch lu lng d liu tc cao da trn cc ng thit lp. LSR c th kt ni vi LER hay cc LSR khc c) ATM LSR: S dng giao thc MPLS trong mng iu khin thit lp knh o ATM, chuyn tip t bo n nt ATM LSR tip theo. d) ATM LSR bin: Nhn gi c nhn hoc khng c nhn phn vo cc t bo ATM v gi cc t bo n nt ATM LSR tip theo. Nhn cc t bo ATM t ATM LSR cn k, ti to cc gi t cc t bo ATM v chuyn tip gi c nhn hoc khng c nhn

2.3 Cc giao thc c bn ca MPLSKin trc MPLS khng bt buc mt phng thc bo hiu n no cho phn phi nhn. Cc giao thc nh tuyn ang tn ti, nh giao thc cng bin (BGP) c ci tin mang thm thng tin nhn trong ni dung ca giao thc. Giao thc ginh sn ti nguyn RPVP cng c m rng h tr trao i nhn. Nhm c trch k thut Internet IETF cng xc nh mt giao thc mi c bit n nh giao thc thc phn phi nhn LDP lm r hn v bo hiu v qun l khng gian nhn. S m rng ca giao thc LDP c s cng c xc nh h tr nh tuyn lin vng (explicit router) da trn cc yu cu v QoS v CoS. Nhng m rng ny cng c p dng trong vic xc nh giao thc (CR)-LDP nh tuyn da trn rng buc. Cc giao thc h tr trao i nhn nh sau: LDP - ch ra cc ch IP vo trong cc bng. RSVP, CR-LDP - s dng cho k thut lu lng v ginh trc ti nguyn. Protocol-independent multicast (PIM) - s dng ch ra nhn trng thi a hng- multicast. BGP - cc nhn bn ngoi

2.3.1 Giao thc phn phi nhn LDPLDP l mt giao thc mi cho phn phi thng tin lin kt nhn n cc LSR trong mng MPLS. N c s dng nh x cc FEC n cc nhn to nn cc LSP. LDP session c thit lp gia cc LDP tng ng trong mng MPLS (khng cn thit phi lin k). cc LDP ngang hng trao i cc dng bn tin LDP sau: Bn tin discovery - thng bo v duy tr s c mt ca mt LSR trong mng


Thit k m hnh mng ATM MPLS Bn tin session - thit lp, duy tr v xc nh cc session gia cc LDP ngang hng. Bn tin advertisement - to ra, thay i v xo nhn nh x n cc FEC

Bn tin notification - cung cp thng tin t vn (advisory) v thng tin libo hiu

2.3.2 Giao thc CR-LDPGiao thc phn phi nhn nh tuyn da trn rng buc CR-LDP (ConstraintBased Routing-LDP) c s dng iu khin cng bc LDP. Giao thc ny l phn m rng ca LDP cho qu trnh nh tuyn cng bc ca LSP. Cng ging nh LDp, n s dng cc phin TCP gia cc LSR ng cp gi cc bn tin phn phi nhn.

2.3.3 Giao thc RSVPRSVP l giao thc bo hiu ng vai tr quan trng trong mng MPLS, n cho php cc ng dng thng bo v cc yu cu QoS vi mng v mng s p ng bng cc thng bo thnh cng hay tht bi. RSVP s dng bn tin trao i ti nguyn t trc qua mng cho lung IP. RSVP l giao thc ring mc IP. N s dng cc gi d liu IP hoc UDP phn bin ca mng thng tin gia cc LSR ng cp. N khng i hi duy tr phin TCP, nhng sau phin ny n phi x l mt mt cc bn tin iu khin.

2.3.4 Giao thc MPLS-BGPMPLS m rng chc nng cho BGP mang cc nhn trong giao thc cng bin BGP, MPLS-BGP cho php b nh tuyn chy BGP phn phi nhn ti cc b nh tuyn bin khc mt cch trc tip thng qua bn tin cp nht ca BGP. Tip cn ny m bo cho qu trnh phn phi nhn v cc thng tin nh tuyn n nh v gim bt tiu ca bn tin iu khin x l.

2.3.5 Kin trc h thng giao thc MPLSThnh phn MPLS li c th chia thnh cc phn sau: Giao thc nh tuyn lp mng (IP) Bin chuyn tip lp mng Chuyn mch da trn nhn mng li chi tit v lc nhn


Thit k m hnh mng ATM MPLS Giao thc bo hiu cho phn phi nhn iu khin lu lng Kh nng tng thch vi cc loi chuyn tip lp 2 khc nhau (ATM, Frame Relay, PPP) Hnh 8 miu t cc giao thc c th s dng trong hot ng MPLS. Phng thc nh tuyn c th l bt k mt trong cc giao thc ph bin. Ph thu vo mi trng hot ng, cc giao thc nh tuyn c th l OSPF, BGP, hay PNNI ca ATM, v.v Phng thc LDP s dng giao thc iu khin truyn tin (TCP) qu trnh truyn d liu iu khin t mt LSR n LSR khc trong sut mt phin m bo tin cy. LDP s dng giao thc datagram ca ngi s dng (UDP) trong sut giai on hot ng discovery ca n. Trong trng hp ny, LSR c gng xc nh cc phn t ln cn v ng thi bo hiu s c mt ca chng trong mng. iu ny c thc hin thng qua mt trao i cc gi tin hello. IP Fwd l phng thc chuyn tuyn lp IP tm ng tip theo bng cch ni a ch di nht trong bng ca chng. Vi MPLS, iu ny c lm bi cc LER. MPLS Fwd l phng thc chuyn tip kt ni mt nhn vi mt cng li ra cho cc gi tin. Cc lp vi miu t trong hnh hp vi ng nt t c th thc hin bng phn cng to nn hot ng nhanh v hiu qu.

Hnh 8: H thng giao thc MPLS



2.4 Hot ng ca MPLSMPLS tch chc nng ca IP ra thnh hai phn ring bit: chc nng chuyn gi tin v chc nng iu khin. Phn chc nng chuyn gi tin vi nhim v gi gi tin gia cc b nh tuyn IP, s dng c ch hon i nhn tng t nh ca ATM. Trong MPLS nhn l mt thc th c di c nh v khng ph thuc vo lp mng. K thut hon i nhn v bn cht l tm nhn ca mt gi tin trong mt bng cc nhn xc nh tuyn ca gi v nhn mi ca n. Vic ny n gin hn nhiu so vi vic x l gi tin theo kiu thng thng, v do vy ci thin hiu nng ca thit b. Cc b nh tuyn s dng k thut ny c gi l b nh tuyn chuyn mch nhn LSR. Phn chc nng iu khin ca MPLS bao gm cc giao thc nh tuyn lp mng vi nhim v phn phi thng tin nh tuyn cho vic chuyn mch. MPLS c th hot ng vi cc giao thc nh tuyn khc nhau nh OSPF v BGP (Border Gateway Protocol). Do MPLS h tr iu khin lu lng v cho php thit lp tuyn c nh nn vic m bo dch v ca cc tuyn l hon ton kh thi. y l mt tnh nng vt tri ca MPLS so vi cc giao thc nh tuyn c in. Ngoi ra, MPLS cn c c ch nh tuyn li nhanh.

2.4.1 Chuyn mch nhnThit b chuyn mch nhn i x vi gi tin (hay t bo) tu theo nhn gn vo c n nh cho gi. Cc thit b chuyn mch xc nh a im v lm cch no gi s c chuyn tip n da trn c s d liu nhn LIB(Label Information Base) ti mi thit b chuyn mch nhn . Thng tin cn thit chuyn tip gi c tng kt trong nhn, thng tin ny bao gm a ch ch , quyn u tin, thnh vin VPN (Virtual path Identifier), lp QoS, v tuyn iu khin lu lng. Trong MPLS, nhn c chiu di c nh, ch c ngha cc b v c mng hay gi trong tiu lp 2 cng vi gi tin. Khc vi chuyn tip IP thng thng, gi tin c phn tch mt ln khi i vo mng MPLS gn cho n mt nhn tng ng vi mt FEC. Trong ni b mng MPLS cc b chuyn mch s da trn cc LIB tro i nhn chuyn tip gi tin n b chuyn mch tip theo, qu trnh ny khng phn tch a ch n IP na.



2.4.2 hnh ca mng MPLS

Hnh9: hnh mng MPLS.

Min MPLS l mt tp k tip cc nt hot ng nh tuyn v chuyn tip MPLS. Min MPLS c th chia thnh Li MPLS (MPLS Core) v Bin MPLS (MPLS Edge) nh hnh 9. Khi mt gi tin IP i qua min MPLS, n i theo mt tuyn c xc nh ph thuc vo nhm chuyn tip tng ng FEC m n c n nh cho khi i vo min. Tuyn ny gi l ng chuyn mch nhn LSP. LSP ch c tnh mt chiu, tc l cn hai LSP cho mt truyn thng song cng. Cc nt c kh nng chy giao thc MPLS v chuyn tip cc gi tin gc IP c gi l B nh tuyn chuyn mch nhn (LSR Label Switching Router). LSR li vo (Ingress LSR) x l lu lng i vo min MPLS; LSR chuyn tip (Triansit LSR) x l lu lng bn trong min MPLS; LSR li ra (Ingress LSR) x l lu lng ri khi min MPLS; LSR bin (Edge LSR) thng c s dng nh l tn chung cho c LSR li vo v LSR li ra.

2.4.3 Cc bc hot ng ca MPLS gi tin truyn qua mng MPLS, phi thc hin cc bc sau: 1. To v phn phi nhn 2. To bng cho mi b nh tuyn 3. To ng chuyn mch nhn 4. Gn nhn da trn tra cu bng 5. Truyn gi tin Ngun gi cc d liu ca n ti ch. Trong min MPLS, khng phi tt c cc lu lng ngun cn thit truyn qua cng mt ng. Da trn cc c tnh lu lng, cc LSP khc nhau c th c to ra cho cc gi tin vi cc yu cu CoS khc nhau.



Hnh 10: To LSP v chuyn tip gi tin thng qua min MPLS Trong hnh 10, LER1 l li v v LER4 l li ra. Bng 1 gii thch cc bc hot ng ca MPLS khi gi d liu truyn qua min MPLS Bng1: Cc hot ng MPLS Hot ng MPLS Miu t

To v phn phi Trc khi d liu bt u truyn, cc b nh tuyn quyt nhn nh to ra lin kt nhn ti cc FEC c th v to bng. Trong LDP, cc b nh tuyn lung xung bt u phn phi nhn v gn nhn/FEC. Thm vo , c tnh lin quan n lu lng v dung lng MPLS c iu chnh thng qua s dng LDP. Giao thc bo hiu nn dng giao thc vn chuyn c th t v m bo tin cy. LDP dng TCP. To bng Khi chp nhn cc lin kt nhn mi LSR to ra mc trong bng c s d liu nhn (LIB). Ni dung ca bng s xc nh mi lin h gia nhn v FEC, nh x gia cng vo v bng nhn vo n cng ra v bng nhn ra. Cc mc c cp nhp bt k khi vic gn nhn c iu chnh li.



To ng chuyn Nh hnh 10, cc LSP c to ra theo chiu ngc vi cc mch nhn mc trong cc LIB. Gn nhn /bng tra B nh tuyn u tin (LER1 trong hnh10) s dng bng cu LIB tm ng tip theo yu cu nhn cho FEC c th. Cc b nh tuyn tip theo s dng bng tm ng i tip theo. Khi gi tin n LSR li ra (LER4), nhn c loi b v gi c truyn ti ch. Chuyn tip gi tin Hnh 10 m t ng i ca gi tin khi n c truyn t ngun ti ch hay t LER1, LSR li vo n LER4, LSR li ra. Ln u tin ca yu cu nhn, cc gi tin khng c nhn ti LER1. Trong mng IP, n s tm a ch di nht tm cc bc tip theo. LSR1 l bc tip theo ca LER1. LER1 s khi pht cc yu cu nhn ti LSR1. Yu cu ny s c pht trn ton mng nh hnh 10. LDP s xc nh ng dn o m bo QoS, CoS. Mi b nh tuyn trung gian LSR2 v LSR3 s nhn gi tin gn nhn thay i nhn v truyn i. Gi tin n LER4, loi b nhn v gi ra khi min hot ng ca MPLS v phn pht ti ch. ng truyn gi tin c ch ra trong hnh 10. Bng 2 l mt v d n gin v bng LIB. Bng 2: V d bng LIB Cng vo 1 2 Nhn cng vo 3 9 Cng ra 3 1 Nhn cng ra 6 7


Thit k m hnh mng ATM MPLS Xem xt v d v 2 lung gi tin vo mt min MPLS: Mt lung gi tin l s trao i d liu theo quy tc gia cc server (v d FTP-file transfer protocol ). Mt lung gi tin khc l lung video cht lng cao yu cu cc k thut lu lng QoS. Cc lung gi tin ny c phn ra thnh 2 FEC ring bit ti LSR li vo. Cc nhn tng ng c kt hp vi lung gi tin ln lt l 3 v 9. Cc cng vo ti LSR l 1 v 2. Giao din li ra cng p ng ln lt l 3 v 1. nh x nhn c thc hin, cc nhn trc ln lt c trao i cho 6 v 7.

2.4.4 ng hm trong MPLSc tnh duy nht ca MPLS l c th iu khin ton b ng truyn gi tin m khng cn xc nh c th cc b nh tuyn trung gian. iu c to ra bi cc ng hm thng qua cc b nh tuyn trung gian c th cch nhiu on. Khi nim ny c s dng trong VPN da trn MPLS. Kho st hnh 11. Cc LER (LER1, LER2, LER3 v LER4) tt c s dng BGP v to LSP gia chng (LSP1). LER1 thng bo bc tip theo l LER2 khi n ang truyn d liu ngun phi i qua hai phn ca mng. Cng vy, LER2 thng bo bc tip theo l LER3 v v.v Cc LER ny s s dng giao thc BGP nhn v lu tr nhn t LER egress (LER4 trong d on ch) theo ton b ng i ti LER li vo (LER1). Tuy nhin, LER1 gi d liu n LER2 n phi i qua mt vi LSR (trong trng hp ny l ba). Do vy, mt LSP ring c to ra gia hai LER (LER1 v LER2) qua LSR1, LSR2 v LSR3. iu ny th hin ng hm gia hai LER. Nhn trong ng ny khc nhn cc LER to cho ng truyn LSP1. iu ng cho c LER3 v LER4 cng nh cc LSR gia chng. Trong phn ny c ng truyn LSP3. c cu trc ny, khi gi tin truyn qua hai phn mng , cc khi nim ngn xp nhn c s dng. Khi truyn qua LSP1, LSp2 v LSP3, gi tin s mang hai nh hon chnh cng lc. Hai nhn c s dng cho mi phn l (1) phn u tin nhn cho LSp1 v LSP2 v (2) phn th hai nhn cho LSP1 v LSP3.



Hnh 11: ng hm trong MPLS Khi cc LER3 nhn cc gi tin tn ti trong mng u tin, cc gi tin s loi b nhn ca LSP2 v thay bng nhn LSP3 trong khi qu trnh trao i nhn LSP1 bn trong gi tin vi nhn ca ng i tip theo. LER4 s loi b c hai nhn trc khi gi gi tin n ch.

2.5 Trin khai ng dng cng ngh MPLS ti Vit NamVic trin khai cng ngh mng mi MPLS cn c cn nhc k lng trc khi tin hnh. Tuy coi coi l cng ngh mng tin tin gii quyt c nhiu nhc im ca mng IP v ATM hin ti nhng khng c ngha MPLS l gii php duy nht cho mng th h sau. c th xy dng c cch tip cn v gii php ph hp cn c nhng nghin cu xc nh r rng i tng v phm vi p dng cng ngh, mc tiu cn t v k hoch trin khai.



2.5.1 Kh nng ng dng ca MPLS ti Vit NamTh gii ang bc vo k nguyn cng ngh thng tin. Xu hng a phng tin, nhng bin ng x hi, ton cu ha trong kinh doanh v gii tr pht trin ngy cng nhiu khch hng s dng phng tin in t. Biu hin u tin ca xa l thng tin l Internet, s pht trin ca n l minh ha sinh ng cho nhng ng thi hng ti x hi thng tin. Vic chuyn i t cng ngh tng t sang cng ngh s em li sc sng mi cho mng vin thng. Tuy nhin nhng loi hnh dch v trn lun i hi nh khai thc phi u t nghin cu nhng cng ngh vin thng mi c lnh vc mng v ch to thit b. C th ni giai on hin nay l giai on chuyn dch gia cng ngh th h c (Chuyn mch knh) dn sang cng ngh th h mi (Chuyn mch gi). iu khng ch din ra trong h tng c s thng tin m cn din ra trong cc cng ty khai thc dch v trong cch tip cn ca cc nh khai thc th h mi khi cung cp dch v cho khch hng. Cng ngh chuyn mch l mt im trng yu trong mng thng tin, vin thng tng lai. Cc cng ngh chuyn mch hin nay, IP v ATM trong tng lai c th khng p ng c cc yu cu trn. Do vy, bc tin ln cng ngh MPLS cng ngh chuyn mch vi nhiu tnh nng mi khc phc cc nhc im ca cng ngh IP v ATM l tt yu.

2.5.2 Mt s nguyn tc khi trin khai mng NGN ti Vit NamMng MPLS l cng ngh mng li ca mng th h sau (NGN). Do vy, khi trin khai mng MPLS phi tun theo cc nguyn tc ca mng NGN. Theo cc kt qu nghin cu v nh hng chin lc trin khai mng th h sau, l trnh chuyn i sang mng vin thng NGN ti Vit Nam thc hin mt s nguyn tc c bn sau: Khng nh hng ti vic cung cp cc dch v vin thng hin c. Vic chuyn i s c thc hin theo tng bc theo nhu cu cn thit. C th thc hin t nt ng trc trc sau n nt truy nhp. Hn ch vic m rng v pht trin cc h thng chuyn mch TDM.Cn xem xt kh nng nng cp v chuyn i mt s h thng tng i c th cung cp c cc dch v mi NGN.


Thit k m hnh mng ATM MPLS m bo vic tng thch vi h thng mng ang tn ti. Tip tc trin khai cc phng thc truy nhp Internet tc cao p ng nhu cu ngi s dng ang tng ln rt nhanh ti mt s khu vc.

2.5.3 M hnh mng MPLS ti Vit NamDa vo cc nguyn tc trn m hnh mng NGN ca VNPT ti Vit Nam vi cng ngh chuyn mch MPLS nh hnh 12.

Hnh 12: S trin khai mng NGN ca VNPT Trong m hnh trn c: Lp t 3 b nh tuyn chuyn mch li ( core switch router) M160 ca JUNIPER vi thng lng chuyn mch 160 Gbit/s t ti thnh ph H Ni, H Ch Minh, Nng. Lp t cc b nh tuyn bin ERX1400 ti cc tnh thnh khc. Bng thng kt ni gia cc b nh tuyn li l 155 Mbit/s.


Thit k m hnh mng ATM MPLS Ti cc tnh thnh s lp t cc Media Gateway (MG), BRAS, DSLAM. MG l giao din gia mng PSTN v NGN truyn ti lu lng thoi ng di. BRAS v DSLAM s dng kt ni cc thu bao xDSL nh hnh 13.

Hnh 13: Cu hnh kt ni ti cc Bu in tnh thnh

2.6 Tm tt chngNh vy chng 2 gii thiu cc thnh phn v hot ng ca mng MPLS. Chng ny cp n cc khi nim c bn ca mng MPLS nh lp chuyn tip tng ng, ng chuyn mch nhn v cc thnh phn c bn ca mng nh b nh tuyn bin nhn, b nh tuyn chuyn mch nhn, c bit, chng ny tp trung nghin cu cc giao thc c bn v hot ng ca MPLS. Hn na, cc trin khai ng dng cng ngh MPLS ti Vit Nam cng c trnh by.



Chng 3: Thit k mng ATM MPLSMt trong nhng bt ng chnh gia cc nh cung cp truyn thng v mng th h sau - NGN (Next Generation Network) l vai tr ca ATM v MPLS. Cc nh cung cp dch v truyn thng u t rt nhiu vo cng ngh ATM cho mt mng li a dch v v khng c nh rt ATM ra khi mng li trong tng lai gn. Tuy nhin cc nh cung cp NGN cho rng ATM cn phi a ra khi mng li v s thiu hiu qu, c bit l khi lu lng ng trc bng n, v thiu kh nng m rng cho cc ng dng IP trong mi trng mng ng trc hon ton IP. H chn phng n trin khai MPLS. Tuy nhin, hin ti vn cha r rng liu MPLS c p ng c hay khng i hi v cht lng dch v - QoS m ATM khng nh v tr ca mnh. ATM cho n gi vn l cng ngh duy nht c kim nghim v thnh cng trong vic tch hp d liu, thoi, v video trn cng mt mng. Hin ti th mt gii php kt hp an ton kh thi l chy c ATM v MPLS trn mng ng trc. Trong tng lai, mng ng trc da trn MPLS l gii php c a chung hn. Nhiu nh cung cp truyn thng ln k hoch hoc ang xc tin th nghim mng MPLS. Nhng nh cung cp mi c thun li l c th i trc tip vo mng MPLS.

3.1 Gii thiuChuyn mch nhn a giao thc (MPLS) m rng kh nng ca cc b nh tuyn IP v cc chuyn mch ATM trong mt vi phng php chnh: MPLS tch hp hon ton iu khin nh tuyn IP vi cc chuyn mch ATM, iu ny cung cp nhng h tr t nhin cc dch v IP nh loi dch v IP v IP a hng (multicast) trn chuyn mch cng nh cc b nh tuyn ATM. MPLS cung cp cc h tr cho kh nng m rng quy m v s dng linh hot cc dch v mng ring o IP trn b nh tuyn v chuyn mch.

MPLS cung cp cc h tr cho k thut lu lng IP, l iu khinmm do cc lung lu lng IP theo cc ngun ti nguyn trn mng.



3.1.1.1

M hnh chc nng mng NGN

Mng NGN theo tiu chun ca t chc Multi-switching Forum (MSF) c m hnh chc nng 4 lp, bao gm: Lp truy nhp Lp truyn ti Lp iu khin Lp ng dng v dch v Lp truyn ti

Lp ng dng/dch vLp iu khin

Lp truy nhpPOTS, ADSL, RF, ATM, IP, ISDN, mobile, Multimedia

Vic hnh thnh cc lp chc nng ca mng NGN s gip cho cc nh khai thc mng c iu kin s dng cc thit b mng ca cc nh cung cp v m rng cc thit b tng lp m khng lm nh hng n cc lp khc. a) Lp ng dng v dch v cung cp cc ng dng v dch v nh: dch v mng thng minh IN, tr tin trc, bng thng gi tr gia tngLp ny lin kt vi lp iu khin thng qua cc giao din m API, nh c th khai pht trin nhanh chng cc dch v trn mng. b) Lp iu khin bao gm cc h thng iu khin, gim st kt ni cuc gi gia cc thu bao thng qua iu khin cc thit b chuyn mch (MPLS) ca lp truyn ti v cc thit b truy nhp ca lp truy nhp. Lp ny c chc nng kt ni cuc gi thu bao vi lp ng dng v dch v, ng thi c chc nng qun l, chm sc khch hng, tnh cc c) Lp truyn ti bao gm cc nt chuyn mch, cc b nh tuyn, cc thit b truyn dn c dung lng ln thc hin chc nng chuyn mch, nh tuyn cc kt ni di s iu khin ca lp iu khin.


Thit k m hnh mng ATM MPLS d) Lp truy nhp dch v bao gm cc thit b truy nhp cung cp cc cng kt ni vi thit b u cui thu bao qua h thng ngoi vi cp ng, cp quang, v tuyn. Thit b u cui thu bao c th l my in thoi c nh,di ng, cc thit b truy nhp tch hp hoc my u cui mng CATV Cc thit b truy nhp cung cp cc loi cng truy nhp cho cc loi thu bao sau: POTS, VoIP, FR, ATM, X25, xDSL, di ngCc thit b cng truy nhp ny thc hin cc chc nng chuyn i cc loi lu lng khc nhau thnh dng tn hiu gi di s iu khin ca lp iu khin v lp ng dng v dch v. Mng MPLS, hay ATM MPLS l mng li trong h thng mng NGN. Trong lun vn ny ch tp trung nghin cu thit k m hnh mng ATM MPLS ny.

3.1.2 Chuyn mch th v cc thut ng chuyn nghnhMPLS l phin bn c chun ho t xut chuyn mch th c ngun gc t Cisco. MPLS v chuyn mch th ging nhau v nguyn l v gn ging c v hot ng. Ti liu ny s dng cc thut ng MPLS nhiu hn cc thut ng chuyn mch th, nh th hin trong bng 1. Ngoi tr mt thut ng l giao thc phn b th (TDP) .TDP v giao thc phn b nhn MPLS gn ging nhau, nhng s dng cc nh dng bn tin khc nhau v mt vi th tc khc nhau.Tuy nhin thut ng TDP khng c s dng trong ti liu do khng c yu cu: ti liu khng cp n s khc nhau gia hot ng ca TDP v LDP. Trong bng 3 thut ng b nh tuyn bin nhn khng c s dng. iu ny l do thut ng tng ng LSP bin c s dng v c 2 thut ng khc nhau dng cho cng mt i tng s dn n nhm ln. LSP bin l thut ng k thut chnh xc hn. Mt vi thut ng khc c s dng nh: ATM MPLS l mt kiu mng MPLS m hot ng vi b chuyn mch ATM lm chuyn mch MPLS. C th hn, ATM MPLS l mt kiu mng ca MPLS m mi nhn khc nhau trn ng truyn c i din bi mt VC khc. MPLS da trn gi tin cp n mt kiu ca mng MPLS m hot ng trong cc mng khng s dng MPLS ATM. C th hn, l mt kiu mng ca MPLS m cc nhn c mang nh l tiu b xung gn trn mi gi. MPLS da trn gi tin cng c bit n nh MPLS khng ATM, MPLS da trn khung v MPLS da trn b nh tuyn. Thut ng MPLS da trn khung khng


Thit k m hnh mng ATM MPLS c s dng trong ti liu ny khi thut dng nh cp n Frame Relay, nhng MPLS da trn gi tin khng nht thit dng n Frame Relay. LSR da trn gi tin l thit b m thao tc v ton b gi tin hn cc t bo. B nh tuyn hot ng da trn gi tin l LSR da trn gi tin. LSR bin ATM cng l mt dng ca LSR da trn gi tin. Chuyn mch v mng ATM truyn thng khng s dng MPLS ATM. Mng ATM truyn thng c th h tr mng MPLS da trn gi tin truyn trong knh o c nh (PVC). Chuyn mch ATM truyn thng c th h tr MPLS ATM trong ng o c nh m ng vai tr nh trung k o. Trong bt k trng hp no, chuyn mch ATM truyn thng thc t khng thc hin chuyn mch nhn a giao thc chng ch n thun h tr xuyn qua ng hm ni gi tin MPLS c mang. Bng 3: Cc thut ng tng ng trong chuyn mch nhn Old Tag Switching Term MPLS Term Tag Switching MPLS; Multiprotocol Label Switching Tag Switch/ed Label Switch/ed Tag (short for Tag Switching) MPLS Tag (thing applied to a packet) Label Tag Core Router-TCR Label Switch Router- LSR Tag Distribution Protocol TDP Label Distribution Protocol - LDP Tag Edge Router-TER Edge Label Switch Router-Edge LSR Tag Switch Controller - TSC Label Switch Controller - LSC Tag Switch/ing Router - TSR Label Switch Router - LSR Tag VC - TVC Label VC - LVC ATM -TSR ATM - LSR TFIB LFIB Tag Switched Path - TSP Label Switched Path - LSP

3.1.3 Cu trc chung ca mng MPLSCu trc thng thng ca mng MPLS ca cc nh cung cp nh ISP c th hin trong hnh 14. Mng MPLS bao gm b nh tuyn chuyn mch nhn bin (LSR bin). Pha khch hng c ni ti nh cung cp mng MPLS. Hnh 14 th hin kt ni gia 9 khch hng v 6 LSR bin, nhng thng c ti vi trm khch hng trn mt LSR. Thit b tin trc khch hng (CPE) hot ng thng thng theo


Thit k m hnh mng ATM MPLS hng IP. N thng khng hot ng trong MPLS. Nu CPE hot ng trong MPLS, cc nh dch v s s dng n mt cch c lp. Ch rng LSR bin l mt phn ca nh cung cp mng v n c iu khin bi nh cung cp. LSR bin l c vai tr ch cht trong hot ng ca mng v khng c ch n CPE di bt k tnh hung no. Nh cung cp c th xc nh v qun l cc b nh tuyn ti pha khch hng, nhng b nh tuyn s chy IP thng thng v bn ngoi mng MPLS .

Hnh 14: Cu trc mng MPLS thng thng. Ch rng thc t s khch hng nhiu hn s khch hng trong hnh v trn.

3.1.4 MPLS v cc kt hp IP trn ATM khcTrong mng ATM, MPLS cho php cc chuyn mch ATM trc tip h tr cc dch v IP, cung cp cc hiu qu cao nht so vi cc cch tip cn khc. IP truyn thng trn ATM kt ni cc b nh tuyn trn cc mch o c nh (PVC). a giao thc trn ATM (MPOA) v cc cch tip cn khc mang lu lng IP trn chuyn mch cc mch o (SVC). IP truyn thng trn ATM, MPOA v cc cch tip cn khc u c cc bt li ging nhau nh: Kh h tr nhiu loi dch v IP trn mng. V d nh lp dch v IP khng th c h tr mt cch t nhin bi cc chuyn mch ATM, v phi c h tr bng cch dch chuyn n tt c cc khi nim cht lng dch v Forum ATM khc.



Kh qun l ti nhng ni dch v IP c h tr. Hai mc nh tuyn phi c qun l: nh tuyn IP (vi OPSF hoc EIGRP hoc tng t) v PNNI hoc nh tuyn tng t trn ATM. MPOA yu cu qun l theo kiu truyn thng. Chuyn dch v nh cc lp dch v IP n cht lng dch v ATM cng yu cu s qun l. Cc dch v IP c th kh km hiu qu trn cc mng ATM. V d nh IP a hng (mluticast) trn cc mng ATM kh thc hin trn qui m ln do s tng tc ca nh tuyn a hng, qu trnh x l thnh vin trong nhm a hng v duy tr ATM VC. Gii hn t l v / hoc nh hng nghim trng gia nh tuyn IP (OSPF,) v mng ATM mng hot ng khng n nh. Nu hn 30 b nh tuyn OSPF c kt ni trong mng li dy c trn cc PVC, IP truyn thng trn ATM c th dn ti lung t ca s cp nhp cc nh tuyn IP v lm nh hng ti mng con. MPOA khng an ton khi kt ni cc b nh tuyn n mi b nh tuyn khc, v ch dnh cho kt ni t host ti cc b nh tuyn hoc t host n host. Cc dch v IP i hi s c gng qun l cc mng con. V d, lp t MPOA yu cu PNNI, bo hiu SVC, ATM ARP,ATMARPserver, NHRP, v NHRP server, cng thm AAL5, nh tuyn IP (OSPF, v.v) v ngn xp IPv4. MPLS trn mng ATM khc phc c tt c cc bt li trn.

3.1.5 Cc bc thit k mng MPLSQu trnh thit k mng MPLS lin quan n cc bc sau, v cc bc c miu t trong cc phn tip theo. Cc bc ny khng nht thit cn thc hin theo th t sau y nhng tt c cn c m bo. Chn kiu thit b Thit k cc im truy nhp dch v Thit k mng ng trc Thit k nh tuyn IP Kim tra kch thc mng MPLS c th c a ra.



3.2 Chn thit b MPLS3.2.1 Cc cu trc ca mng MPLSMng MPLS c b nh tuyn chuyn mch nhn bin (LSR) v LSR li ni vi nhau nh trong hnh 14. Tuy nhin cc kt ni c th c lp t trn nhiu kiu thit b khc nhau, kt hp vi thit b truy nhp trong nhiu cch khc nhau. iu ny c th hin trong hnh 15.

a. MPLS da trn gi tin n gin

b. ATM MPLS vi LSR bin da trn b nh tuyn

c. Kt hp ATM v MPLS da trn gi tin



d. ATM MPLS vi b tp trung truy nhp

e. ATM MPLS vi thit b bin ATM tch hp

f. ATM MPLS vi Backhaul v ng hm



g. Mng ng trc kp Hnh 15: Thit b trong mng MPLS a) MPLS da trn gi tin n gin Cu trc mng MPLS n gin nht c th hin trn hnh 15(a). Cu trc ny p dng trong mng ch c b nh tuyn, iu ny c th ng dng h tr dch v VPN hoc iu khin lu lng. Trong cu trc ny, pha khch hng c c kt ni trc tip n LSR bin da trn b nh tuyn. Cc LSR bin c kt ni n cc LSR khc, iu ny cng da trn nn tng b nh tuyn. Cc b nh tuyn kt ni ln nhau bi mi loi lin kt o: ni tip, ethernet, gi tin qua SONET, v.vv gi tin c gi i vi tiu MPLS trn cc lin kt . Cc b nh tuyn lin quan thng l Cisco 7200, 7500, hoc cc b nh tuyn gigabit 1200-series. B nh tuyn min trung bnh (Cisco 3600 v 4700 series) c th c s dng trong cc ng dng di thng thp. Bin i trong dng cu trc ny l v tr m ATM PVC lin kt im - im gia cc b nh tuyn. iu ny c th c s dng trong sut qu trnh dch chuyn n ATM MPLS. b) ATM MPLS vi LSR bin da trn b nh tuyn Cu trc mng ATM MPLS n gin nht c th hin trong hnh 15(b). Nh trong trng hp trn, pha khch hng c kt ni trc tip n LSR bin da trn b nh tuyn, thng l b nh tuyn 7200 hoc 7500 series. LSR bin c kt ni bi ng kin kt ATM n thit b li l ATM LSR. ATM LSR c th l


Thit k m hnh mng ATM MPLS chuyn mch BPX 8650 IP+ATM, LS1010, 8500 MSR, v cc chuyn mch ATM khc sau nh: MGX 8800 vi PXM-45. Chuyn mch ATM mang cc gi tin vi nhn ATM MPLS, iu ny c ngha l trn mi ng lin kt ATM cVC nhn MPLS khc nhau cho mi nhn. c) Kt hp ATM v MPLS da trn gi tin C th c mt mng vi s kt hp ca ATM v MPLS da trn gi tin. V d n gin nht ca mng ny c th hin trong hnh 15(c). Trong mng nh trng hp ny, mt vi ng lin kt hot ng trn MPLS da trn gi tin, v mt vi ng lin kt hot ng trn ATM MPLS. Thit b giao din gia MPLS da trn gi tin v ATM MPLS l cc b nh tuyn ng vai tr ging nh LSR bin ATM: bt k loi no t Cisco 3600 n Cisco 12000. d) ATM MPLS vi thit b truy nhp ring Mng ATM MPLS vi LSP bin da trn b nh tuyn cng c th s dng cc thit b truy nhp ring, nh th hin trong hnh 15(d). iu ny s xy ra khi truy nhp c yu cu t thit b m khng h tr dch v MPLS. C ba trng hp thng thng m truy nhp ny c yu cu: Truy nhp c yu cu n hai dch v IP v dch v ATM PVC thng qua thit b truy nhp khng h tr MPLS. V d thng thng nht ca thit b truy nhp ny l MGX 8220. Thit b truy nhp khng c phn mm h tr MPLS. S lng ng dy truy nhp di thng thp cao hn c th c h tr bng cch s dng thit b truy nhp ring tt hn cch s dng n gin LSR bin. Lu lng khch hng c mang thng qua thit b truy nhp n bin LSR. Gia thit b truy nhp v LSR bin c ng lin kt logic khc nhau cho mi khch hng. c th l Frame Relay hoc ATM PVC, hoc ng lin kt PPP. e) ATM MPLS vi thit b truy nhp tch hp IP+ATM Kiu mng trong phn trc c th lm n gin ha nu thit b truy nhp h tr chc nng LSR bin nh Frame Relay, ATM, hoc dch v truy nhp khc. Trng hp ny c th hin trong hnh 15(e). Trong trng hp chuyn mch bin IP +ATM, mt thit b cho php truy nhp n c cc dch v MPLS v cc dch v


Thit k m hnh mng ATM MPLS PVC v SVC. Chuyn mch bin IP+ATM bao gm b tp trung truy nhp chung BPX 8680, MGX 8850 v 6400. f) ATM MPLS s dng chuyn mch ATM truyn thng Mng MPLS c th s dng thit b ATM truyn thng. Trng hp ny thng c lm nh mt bc chuyn i MPLS ban u n mng ATM ang tn ti. Chuyn mch ATM truyn thng c th c s dng trong ba cch nh th hin trong hnh 15(f). Backhaul khi thit b truy nhp l t xa n LSR bin. Thit b truy nhp c kt ni n LSR bin bi PVC chuyn mch thng qua mng ATM. ng hm thng qua chuyn mch ATM gia LSR bin v LSR ATM. Trong trng hp ny, LSR bin khng cn lp t lin k LSR ATM, nhng c th c kt ni thng qua mng ATM. nghm thng qua chuyn mch ATM gia cc LSR ATM. Trong trng hp ny, mng li s dng chuyn mch ATM kiu truyn thng cng nh chuyn mch ATM. g) Mng ng trckp Nh cung cp dch v c th mun gi li c s h tng mng ATM ang tn ti trong khi xy dng c s h tng mng MPLS mi (mng MPLS ATM hoc MPLS da trn gi tin) bn cnh c s h tng c. Thit b bin IP+ATM Cisco h tr tt vn ny cho php khch hng truy nhp n c dch v v mng MPLS cng nh mng ATM c thm ch ch cn dng mt ng truy nhp. Kiu mng ny c th hin trong hnh 15(g). Thit b truy nhp IP+ATM c th l nhng thit b c dng trong hnh 15(e). Mng trong hnh 15(g) h tr cc chc nng v dch v ging nh mng trong hnh 15(e) nhng mng hnh 15(g) i hi nhiu thit b hn. 3.2.2 Chn thit b MPLS Cisco a) Chn thit b bin MPLS ATM C bn vn cn xem xt khi chn thit b bin MPLS ATM: Kiu dch v c yu cu IP +ATM nh PVC u cui n u cui v cc dch v SVC cng nh cc dch v IP, hoc ch IP.

Kiu ng dy truy cp S lng ng dy truy cp


Thit k m hnh mng ATM MPLS Cc yu cu cho d phng v tin cy a ra cc gii php khi cc thit b gim ti mc ti thiu (warm standby) hoc hon ton chng li (hot standby) s ph v cc lung d liu trong trng hp phn mm hay phn cng b hng, hoc cc thnh phn ring bit nh card cng c th b hot-swapp. Hot standby ngha l khng hoc hu nh khng (di 1 giy) c s gin on ca cc lung d liu t u cui n u cui trong trng hp thit b hng, bng cch khng phi nh tuyn li tr khi thit b hng. Mc d phng cho thit b bin MPLS c th c phn loi nh sau: o None - Thit b bin khng c tnh nng d phng. Mng phi da vo s nh tuyn li p ng tin cy. Pha khch hng phi l thu bao i (dualhomed) ti 2 thit b truy nhp khc nhau m bo tnh tin cy ca thit b. o D phng b x l - Thit b bin c d phng i ca b x l v backplane vi d phng m hoc nng (warm standby hay hot standby). Khi card cng (sport card) khng c d phng i, mng vn phi da vo nh tuyn li m bo tin cy. Pha khch hng vn phi l dual-homed m bo thit b ng tin cy trong trng hp card cng b hng, nhng khch hng c l thu bao i (dual-homed) ti hai card khc nhau trn cng mt thit b truy cp. o D phng y - Thit b bin c b x l d phng v card cng. Pha khch hng s nhn dch v ng tin cy t thit b bin ngay c khi h l thu bao n(single-homed) . Khuyn ngh cho cc thit b da trn cc yu cu trn c th hin trong bng 2. Trong tng lai, Cisco dng nh h tr MPLS trn hu nh hoc ton b cc b nh tuyn vng trung bnh (mid-range) v high-end, hu nh hoc tt c cc chuyn mch ATM, v hu nh hoc tt c cc sn phm truy nhp vi kh nng nh tuyn. Bi vy, nhiu thit b bin MPLS s tr nn c hiu lc trong tng lai. Chi tit hn v tt c cc sn phm trn ti trang web http://www.cisco.com Mt vi vn thit thc cn ghi nh khi kim tra sn phm c bit cho nhng sn phm c s dng nh LSR bin ATM: Khi xem xt s ng dy truy nhp c h tr, hy m s khe cm card c s dng bi giao din MPLS ATM. V d nh b nh tuyn 7206 Cisco c 6 khe cm card, v bnh thng h tr 48 cng ethernet (hay 8 trn mi khe). Tuy nhin, khi s dng b nh tuyn 7206 Cisco nh LSR bin ATM, t nht c mt khe


Thit k m hnh mng ATM MPLS phi c s dng cho giao din ATM. Nh vy, s cng ethernet thc t ca LSR ATM 7206 Cisco l 40 cng ethernet. Mt vi LSR bin s dng khe cm card card thc hin chc nng LSR bin, v cc khe ny cn phi a vo m. V d nh b tp trung truy nhp ton b 6400 Cisco c 8 khe cm card, nhng khi hot ng nh LSR bin, t nht mt trong cc khe cm phi c s dng cho card b x l nh tuyn nt v khng c card ng dy. Mt vi LSR bin c th gii quyt lu lng ca lung MPLS m bin i theo s card ang x l. V d nh, ti thi im ny card b nh tuyn nt (NRP) trong b tp rung truy nhp ton b 6400 Cisco c th x l 150Mb/s fullduplex ca lu lng bin MPLS. iu ny c ngha l vi phn s 25 % hot ng thng thng, Cisco 6400 v mt NRP c th qun l bn ng dy truy cp OC3/STM-1;do vy Cisco 6400 vi 2 NRP c th qun l tm ng dy OC-3/STM-1. S khe cm c thc hin bi card b x l cng phi c m khi tnh ton s ng dy truy nhp h tr cho bt k cu hnh ring no. Bng 4: Chn thit b bin mng MPLS cho mng MPLS ATM Thit b B nh tuyn 3600 Kiu dch ng dy truy nhp v ch IP S khng ng b tng i nh, modem, ni tip, frame relay, ethernet 10Mb/s, BRI $ PRI ISDN, chui E1/T1, ethernet nhanh, OC3/STM-1 ATM, giao din m thanh v nhiu loi khc H tr Ch gii d phng Khng S lng nh LVC c h tr trn card ATM s dn ti gii hn kch thc mng MPLS. Khng khuyn nghi cho nh cung cp mng MPLS ATM S lng tng i nh ca Khng S lng nh chui ni tip/frame relay, LVC c h ethernet 10Mb/s, BRI $ PRI tr trn card ISDN, chui E1/T1, ethernet ATM s dn nhanh, E3, T3, hoc OC3/STMti gii hn

B nh tuyn 4700

Ch IP


Thit k m hnh mng ATM MPLS 1 ATM v nhiu loi khc kch thc mng MPLS. Khng khuyn nghi cho nh cung cp mng MPLS ATM Mc ti thiu cho nhng nh cung cp mng. Cc b thch nghi cng PA-A2 CES-ATM khng h tr lin tc MPLS

B nh tuyn 7200

ch IP

Ni tip/frame relay ti E1/T1, Khng ethernet nhanh v 10Mb/s, ISDN BRI, HSSI, ni tip tc cao, E3, T3 hoc OC3/STM1 ATM, SONET/SDH trn gi tin v cc loi khc

B nh tuyn 7505, 7507, 7513, hoc 7576 12008/ 12012

ch IP

Ni tip/frame relay ti E1/T1, ethernet nhanh v 10Mb/s, ISDN BRI, HSSI, ni tip tc cao, ATM, SONET/SDH trn gi tin v cc loi khc

d phng b x l wramstandby vi RSP kp D phng b x l warmstandby Khng Ph hp vi tc cao gia nhng nh cung cp ngang hng Cat 5500 l c bn vi chuyn mch LAN nhng cng gii hn kh nng LSR bin

ch IP

POSIP v ATM ti tc OC3 n OC48 v ethernet gigabit

Catalyst 5500 vi modunch uyn mch nh tuyn

IP+ATM

Ethernet 10Mb/s v nhanh, E3, T3,OC3/STM-1, ad OC12/STM-4 ATM v nhng loi khc


Thit k m hnh mng ATM MPLS 6400 IP+ATM ATM t tc E3/T3 n STM-4, ethernet v ethernet nhanh Lng ln Frame relay 56k/64k, Frame relay T1/E1, channelize, ATM v Frame re lay tc cao hn , serial v channelize Lng ln FR channelize/unchannelize, ATM ti tc T1/E1, T3/E3, OC3/STM-1, giao din Subratev nhng loi khc D phng b x l warmstandby Full Card RPM Warm-to- hay RPM-PR hot c yu cu standby

MGX 8230, 8250 & MGX 8250 vi PXM-1 IGX 8400 Series

IP+ATM

IP+ATM

Full Warm-toHot Standby

BPX 8680

IP+ATM

Lng ln Frame relay 56k/64k, T1/E1ATM, Frame relay v channelize. ATM ti tc E3/T3 n STM-4 v nhng loi khc

Full Warm-toHot Standby

H tr LSR bin c ngh cho IGX 8400 vi URM, vn chuyn H2 CY01. NPM68 c yu cu. Phn mm chuyn mch TBD Card trung k BXM phi c s dng. Card BXM Model-DX hay EX c khuyn ngh mnh m. Card BCC phi l BCC3-64 hay hin i hn. Card BCC4 c khuyn ngh mnh.


Thit k m hnh mng ATM MPLS b) Chn b nh tuyn chuyn mch bin nhn ATM C nm vn cn xem xt khi la chn LSR ATM: Dng trung k S lng trung k S lng cc kt ni c h tr Xem kt hp VC c c yu cu khng Cc yu cu cho d phng v tin cy , nh tho cp trn Khuyn ngh v thit b da trn cc yu cu trn c th hin trong bng 5. Trong tng lai, mc ch ca Cisco h tr MPLS trn hu ht hay ton b chuyn mch ATM. Do vy, nhiu LSR ATM s tr nn hu hiu trong tng lai. Thm vo , chuyn mch ATM truyn thng c th c s dng trong mng MPLS Cisco nu tunnelling c s dng, ph thuc vo s hn ch ngha. c) B nh tuyn chuyn mch nhn khng da trn chuyn mch ATM LSR khng da trn chuyn mch ATM c th cng c s dng. C th hn cc b nh tuyn sau y c th dc s dng nh LSR: Cc b nh tuyn Cisco 3600 v 4700 series Cc b nh tuyn Cisco7200 v 7500 series Cc b nh tuyn chuyn mch Giagbit Cisco 12000 series S dng nhng b nh tuyn ny, MPLS c th h tr o trn bt k kiu ng lin kt no: ATm, SONET trn gi tin, ethernet v.v LSR da trn b nh tuyn khng h cc kt ni mch o ATM . Bng 5: Chn LSR ATM Thit b Dng v s lng trung k ATM S lng kt ni c h tr 64k Kt hp VC c h tr ? C H tr d phng Khng

Ch gii

LS1010 32 x T1/E1vi nghch o a ghp knh trn ATM (IATM), 32 x T3/E3, 32 x OC3/STM-1,8x OC12/STM-4


Thit k m hnh mng ATM MPLS 6400 16xT3/E3 /ATM-1, 8x OC 12/STM 4 64k C D phng b x k warmstandby

IGX840 240xT1/E1, 0 180xT3/E3, 120xOC3/STM

120k

Khng D Tt c giao trong phng din MPLS ln thc hon ton phi trn card hin du UXM, NMPtin 64B c yu cu C D phng b x l warmstandby

8540 MSR

64xT1/E1vi IMA, 256k 64xT3/E3, 64xOC3/STM1,32xOC12/STM-4, 8x Oc12/STM-16 144xT3/E3, 96xOC3/STM-1, 24x OC12/STM-4 192k

BPX 8650

CY2001 D Tt c cc phng giao din hon ton MPLS phi trn card BXM, card BXM modelDX hay EX c khuyn ngh mnh m. Card BCC phi l BCC3-64 hay mi hn. Card BCC4 c khuyn ngh mnh m



3.2.3 IP+ATMIP+ATM l sc mnh chnh ca chuyn mch ATM Cisco. IP+ATM c s dng miu t cc thit b Cisco m cc thit b h tr ng thi cc dch v ATM truyn thng (PVCs, SVCs, SPVCs, PVPs, v.v) v truyn ti IP ti u s dng MPLS. Khi nim chuyn mch IP+ATM c ch ra trong hnh 16(a). Mt chuyn mch n bao gm hai chuyn mch ring logic vi nhau: mt b nh tuyn chuyn mch nhn ATM MPLS ti u cho truyn ti IP v chuyn mch PVC/SVC ATM truyn thng. Mi trung k c th h tr c hai PVC (hoc SVC, v.v) v VC nhn MPLS (LVCs). Mc d chuyn mch IP+ATM gm hai chuyn mch ring logic vi nhau nhng v mt vt l n ch c mt chuyn mch. Tuy nhin chuyn mch IP+ATM c hai (hoc nhiu hn) b phn mm iu khin ring. Mt trong cc b phn mm iu khin PVC, SVC,v.v v b phn mm khc iu khin MPLS. Nhng b iu khin ny hot ng mt cch c lp cho php mt chuyn mch vt l n hot ng nh hai (hoc nhiu hn) chuyn mch o. Trong cc chuyn mch nh BPX 8650 v MGX 8850, b iu khin c lp ny c thc thi nh s dng giao din iu khin chuyn mch (SCI). SCI cho php hai (hoc nhiu hn) b iu khin ring iu khin mt cch c lp chuyn mch n, nh ch ra trn hnh 16(b). Phn mm iu khin MPLS c xc nh v mt vt l trong b iu khin chuyn mch nhn (LSC). Trong BPX 8650, LSC l thit b tch t gi chuyn mch chnh. Trong MGX 8850, LSC s c da trn modun x l nh tuyn (RPM) trong chnh gi chuyn mch. B iu khin SCI khc c th l phn mm hot ng trn card iu khin chuyn mch. LS 1010 v 8540 MSR thc thi cc chc nng tng t nh chc nng ca SCI s dng giao din phn mm bn trong. cho php cc mt phng iu khin hot ng c lp, cch thc SCI trong chuyn mch phi cp ngun ti nguyn n mt phng iu khin khc (MPLS, PNNI, v.v) . Trong BPX 8650, ngun ti nguyn cho PVC c iu khin bi nh tuyn t ng c dnh ring trong mt cch tng t. Cc ngun ti nguyn c phn chia theo cch ny l: Khng gian VPI/VCI trn trung k - Mi mt phng iu khin nhn mt vng VPI s dng. Di thng - Mi mt phng iu khin c m bo mt di thng xc nh vi mc ch iu khin np kt ni (CAC). Vi phn chia mm, c mt qu


Thit k m hnh mng ATM MPLS di thng c phn chia gia cc bn iu khin cho mc ch CAC. Ngay c vi phn chia cng di thng d tha khng c s dng bi mt bn iu khin c gi tr trn c s t bo - t bo n cc bn iu khin khc. Hng i lu lng - Mt trong nhng gii php ca IP+ATM l lung lu

lng MPLS nhn cc hng i lu lng khc trn chuyn mch hn lu lng PVC v SVC. iu ny c ngha l lung lu lng c th c iu khin bi hng i h tr trc tip khi nim lp dch v MPLS. S chn la l chuyn i cu hnh bng tay ti cc kiu dch v ATM Forum. S cn thit cho cc chuyn i l mt trong nhng bt li chnh ca h thng IP qua ATM tch khi MPLS, v IP+ATM trnh c nhng bt li trn.

a. Tng quan logic ca mt chuyn mch IP+ATM

b. SCI v b iu khin

c. Phn chia ng trung k



d. C hai chc nng trong ng d liu

e. MGX 8850 hay Cisco 6400Hnh 16: IP+ATM

Phn x l cu hnh cho cc chuyn mch IP+ATM l vic phn b cc ngun ti nguyn ny n cc bn iu khin khc nhau. iu ny lin quan n vic to s phn chia khc nhau ca cc ngun ti nguyn lin kt cho cc bn iu khin khc nhau, nh th hin trong hnh 16(c). S dng IP+ATM IP+ATM c th c s dng a ra cc dch v MPLS, v cc dch v PVC,SVC, v.vtrn cng mt mng. iu ny c ngha l tt c (hay nhiu) chuyn mch trong mt mng hot ng nh LSR ATM v chuyn mch ATM truyn thng, nh th hin trong hnh 16(a). Cc dch v ATM truyn thng c th cng c s dng cng vi dch v MPLS. Hnh 16(d) cho bit vic s dng PVC lin kt n lung lu lng IP thng thng t pha khch hng thng qua LSR bin ATM. Mt PVC c s dng trong kiu ny c gi l PVC truy nhp MPLS. Cc PVC khc l PVC truyn thng nh phn ca dch v PVC t u cui n u cui truyn thng. Lu lng t bin LSR c th sau dn quay tr li thng qua chc nng LSR ATM trong cng mt chuyn mch h tr PVC truy nhp MPLS, hoc thng qua cc chuyn mch khc c la chn. Trong trng hp ny, ng d liu


Thit k m hnh mng ATM MPLS u cui n u cui cho lu lng IP ca khch hng c th bao gm c hai PVC truy nhp MPLS v VC nhn MPLS. Chuyn mch bin IP+ATM tch hp nh MGX 8850 hay Cisco 6400 h tr chc nng LSR ATM cng nh cc chc nng chuyn mch truy nhp truyn thng v chuyn mch PVC. Thm vo , chc nng LSR bin cng c tch hp trong thit b. iu ny c th hin trong hnh 16(e). Trong MGX 8850, chc nng nh tuyn c h tr bi phng thc ca modun b x l nh tuyn (RPM) v modun b x l nh tuyn nt (NRP) c s dng trong Cisco 6400. Mi RPM hay NRP hot ng nh LSR bin. Trong MGX 8850, mt trong nhng RPM s hot ng ng thi nh LSC v LSR bin.

3.3 Thit k mng MPLSMc tiu ca vic thit k mt mng MPLS trc khi tin ti lp t l cung cp mt mng s hot ng chnh xc v s mang n s hp l ti thiu p ng mc ch thc hin. Do bn cht khng lin kt ca cc lung lu lng IP, cc khch hng khng th ch ra chnh xc mt thit b vn chuyn m h mun gi lung lu lng n. Bi vy khng c kh nng thit k hon ho mt mng trong thi gian u. Cc bc thit k ban u c mt mng hot ng: Thit k cc im truy cp dch v Xc nh cc lin kt ng trc trong mng Thit k nh tuyn IP Xc nh khng gian VC nhn MPLS Cc bc thit k sau cng l tin hnh ti u mng thit k hot ng lin tc : Ci tin thit k khi mng hot ng Cc bc ny c xem xt trong cc phn tip theo.

3.3.1 Cu trc cc im truy cp dch vThit k cc im hin din (PoP) cho mng MPLS ATM c thc hin bi: La chn kiu ng dy truy cp v thit b cho mng nh tho lun trn Cp pht cc PoP m c xc nh rng ln bi cc thnh ph Dn s ca khu vc ngi s dng bao quanh mi vng cp pht.


Thit k m hnh mng ATM MPLS Mt vi thit k PoP in hnh c ch ra trong hnh 17. a) LSR bin ATM n Ni thit b LSR bin n cho vic h tr s lng v kiu ng dy truy cp trong mt im truy cp dch v th cu trc n gin c th hin trong hnh 17(a) l . S lng ng dy truy cp (thng hng chc hay hng trm) c a vo trong LSR bin n c lin kt ti phn cn li ca mng ATM MPLS. S lng v kiu ng dy c h tr bi LSR bin n c miu t trong bng 4. b) Nhiu LSR bin v mt LSR ATM Mt PoP c th yu cu nhiu hn mt LSR bin do s lng ln cc ng dy truy nhp c h tr ti v tr . Hay cc kiu LSR bin khc nhau c th c yu cu do nhiu kiu ng truy cp khc nhau c h tr. Hnh 17(b) c mt vi cc LSR bin trong PoP, n cng bao gm mt LSR ATM. Mt LSR ATM: mt PoP Chuyn mch cc b lu lng lu thng gia cc bin LSR khc trong

Tp trung lu lng lu thng t mt PoP n mt b cc ng lin kt ATM MPLS n. C th la chn l cc b ng lin kt n tt c cc LSR bin hay s dng mt LSR bin mang lu lng n cc LSR bin cn li. Ci thin kh nng nh tuyn. Ch mt b giao thc nh tuyn IP (v d OSPF) ngang hng c yu cu t mt LSR ATM n cc im khc trong mng MPLS. Khng c LSR ATM, cc giao thc nh tuyn IP ngang hng ring c yu cu t tt c cc LSR bin. Tu thuc vo cc yu cu v tin cy, cc cp ng lin kt d phng c th c s dng gia cc LSR bin v LSR ATM.



Hnh 17: Cu trc im hin din cho mng MPLS ATM c) PoP bin vi cc b tp trung truy nhp BPX 8650 v MGX 8220 Nh mt m rng ca m hnh trc, cc b tp trung truy nhp truyn thng c th c s dng b xung cho cc LSR bin v mt LSR ATM. iu ny thch


Thit k m hnh mng ATM MPLS hp trong trng hp c tho lun trong phn Cu trc cho cc mng MPLS. Mt v d ca kiu PoP ny s dng gi truy nhp MGX 8220, LSR bin Cisco 7200 hay 7500, v Cisco BPX 8650. Trng hp ny c th hin trong hnh 17(c). Lu lng IP t cc b tp trung truy nhp c mang trong cc PVC ATM n cc LSR bin. Cc lu lng IP ny c th c mang thng qua BPX 8650 tng t hot ng nh mt LSR ATM, nh l mt chuyn mch IP+ATM. LSR bin trong PoP nh vy c th c ba kiu cu hnh khc nhau: Thng thng, mt hoc nhiu LSR bin s c dnh cho vic lu thng cc lu lng IP trn PVC cc bin. B nh tuyn mang nhn x trong hnh 4(c) c cu hnh kiu ny. B s thng c t nht hai giao din ATM: mt cho truy nhp PVC (t b tp trung truy nhp) v mt cho lu lng MPLS ATM. Tuy nhin, la chn vi dung lng thp hn l s dng nhiu giao din con trn mt giao din ATM: nhiu thit b u cui PVC v mt giao din con MPLS ATM. Mt LSR bin lu thng vi PVC truy cp c th cng c ng dy truy cp khch hng kt cui trc tip trn n. B nh tuyn nhn z trong hnh 17(c) c cu trc kiu ny. Cng c th l cc LSR bin trong PoP khng cho lu thng tt c cc PVC, v ch c ng dy truy cp kt ni trc tip. B nh tuyn y c kiu cu hnh ny. S lng cc LSR bin yu cu da trn: Tng s cc ng dy truy cp Ton b di thng ca cc ng dy truy cp tnh t mc s dng trung bnh. V d, tng di thng ca cc ng dy truy cp c th l v d nh 1 Gb/s nhng s ngi s dng c th khng vt qu 500Mb/s. Kh nng ca mt b nh tuyn 7500 v 7200 vn hnh chc nng bin MPLS gn ging kh nng IP truyn thng s dng chuyn tip gia tng Cisco (CEF). V d b nh tuyn 7200 vi b x l NPE 200c th h tr gn 200 Mb/s lu lng bin MPLS vi cc gi tin IP c kch thc thng thng. B xung cho cc LSR bin, mt BPX 8650 cn mt b nh tuyn 7200-series hot ng nh mt LSC. B nh tuyn nhn c trong hnh 17(c) hot ng nh mt LSC. B nh tuyn ny c khuyn ngh mnh dnh cho vic hot ng nh mt LSC v cng khng c s dng cho lu lng d liu chuyn tip.


Thit k m hnh mng ATM MPLS d) Cisco 6400 v LSR bin MGX 8850 MGX 8850 v Cisco 6400 tch hp cc chc nng c miu t trong v d trc v trong mt thit b n, iu ny c minh ho trong hnh 17(d). N bao gm: Mt b tp trung a dch v vi nhiu kiu ng dy truy cp Frame Relay v ATM cng nh cc ng circuit emulation. Kh nng truy cp m thanh v cc kiu ng dy truy cp khc s c b sung v sau . Mt hay nhiu LSR bin. Mi LSR bin l mt card module b x l nh tuyn (RPM) trong trng hp MGX 8850 hay mt card b x l nh tuyn nt (NRP) trong trng hp dng Cisco 6400. S lng cc RPM hay NRP yu cu hot ng nh cc LSR bin ph thuc: o Tng s cc ng dy truy cp o Ton b di thng ca cc ng dy truy cp tnh t mc s dng trung bnh. V d, tng di thng ca cc ng dy truy cp c th l v d nh 1 Gb/s nhng s ngi s dng c th khng vt qu 500Mb/s. Mt RPM vi b x l NPE 150 c th h tr chc nng bin MPLS cho cc ng dy truy cp 700. N s h tr gn 150Mb/s lu lng bin MPLS vi gi IP kch thc bnh thng. NRP cng tng t. Gii hn ny s tng nn trong tng lai nh vo s pht trin phn mm v phn cng. c bit RPM-PR s c gii hn cao hn ng k. Mt LSR ATM. Trong Cisco 6400, b x l chuyn mch nt cng hot ng nh mt LSC. MGX8850 vn khng c LSC nhng c kh nng LSR-ATM. Cisco 6400 v MGX 8850 cng c kh nng IP+ATM e) LSR ATM ng ring l Mt vi phn trong mng c th c vai tr ch l mt chuyn mch. Trong mng MPLS ATM, cc phn ny s gm mt LSR ATM n c ch ra trong hnh 17(e) hay c th l mt cp LSR ATM d phng. LSR ATM in hnh c th l BPX 8650 hay MSR 8540. Trong mt vi mng, n c th c thay bi LSR da trn b nh tuyn nh ch ra trong hnh 17(f). B nh tuyn cisco 7500 hay 12000-series c th ph hp vi ng dng ny. LSR li thng c kh nng LSR bin kh tt. V d BPX 8650 hn ch dung lng LSR bin ti phn ca b iu khin chuyn mch nhn ca n.



3.3.2 Xc nh cc ng lin kt ca mng MPLSPhn ny c xu hng l phn hng dn cc bc xc nh ng lin kt trong mng MPLS nh nhng khng phi l cch tt nht to nn mng . Cc nh cung cp khc nhau s c phng thc ca ring h cho vic thit k v vn hnh mng nhng tt c nhng nh cung cp s gn nh tng t nhau v phng thc m c miu t trong bn phn hng dn ny. Nhc li rng thit k mng ban u khng th to ra mt mng hon ho. Mt vi iu gn ng c thc hin trong qu trnh ny m dn n mng hot ng, nhng iu gn ng khng nht thit phi ti u. Bc cui cng trong qu trnh hng dn ny l ti u ha mng v iu ny ac tho lun trong phn Thit k mng hot ng lin tc. 1. Thit k cc im truy cp dch v bin v cch b tr ca cc im Bc u tin trong thit k mng MPLS s l chn c, kiu v cch b tr cc im truy cp dch v theo nhng vn c miu t trn. Mt v d c ch ra trong hnh 18. V d ny l da trn mng Australia. Australia c chn cho v d ny bi v n nh to nn mng thc t ph hp. PoP bin c ch ra trong hnh 18(a) c chn da trn c lng yu cu lin kt ca khch hng m c ch ra trong hnh 18(b). PoP LSR bin da trn BPX 8600 (bao gm mt vi gi MGX 8800 v BPX 8650 cho kt hp) c s dng Sydney v Melbourne, nhng ni ny c c di thng lin lc v s lng cc ng lin kt ln nht trong v d ny. MGX 8800 c s dng Brisbane. Adelaide v Perth l cc trung tm nh hn m c th c p ng tng xng bi cc PoP da trn b nh tuyn trong v d ny. 2. Xc nh lu lng t mi im truy cp dch v Da trn tng s cc di thng ng dy truy nhp, xc nh tng lu lng t cc khch hng n mi PoP c th c xc nh. Xc nh chu k -bn c th c s dng v d nh xc nh t l trong sut thi gian bn nht trong ngy. iu ny m bo cc thng s thch hp. nh gi ng mc c th l tng cc di thng ng dy truy cp ti mi PoP nh trong hnh 18(b). Tuy nhin, thng hp l khi ly c lng thp hn mt lng no , v d 50% tng bng thng truy nhp nh ch ra trong hnh 18(c). 3. Xc nh ma trn lu lng Vic x l chnh xc bc ny s thay i t mng ny n mng khc. Australia, v d hai trung tm kinh t chnh l Sydney v Melbourne vi Sydney l


Thit k m hnh mng ATM MPLS rng hn khng ng k. Trong mng MPLS ln cho lu lng IP kinh doanh gia cc tiu bang, mt xp x hp l u tin c th tng ng l 50% lu lng s n Sydney, 40% n Melbourne, 5% n Brisbane v 2.5 % n Adelaide v Perth. Nh cung cp dch v ang tn ti s c th xc nh cc gi tr lu lng cho cng ca h. Da trn phn trm phn b lu lng xc nh v tng lu lng PoP t bc 2, ma trn lu lng c th c xc nh. Ma trn lu lng cho v d ny l trong bng 6. Trong mng thng thng, ma trn ny gn nh i xng. V d trong bng 6, lu lng t Sydney n Adelaide l 12.5Mb/s nhng lu lng t Adelaide n Sydney l 25Mb/s. Nu lu lng i xng hn khong 2:1 hay 3:1 th c li trong vic xc nh lu lng hay dng m hnh. 4. Xc nh cc lung lu lng 2 chiu Trong mng IP, lu lng t x ti y s thng chy dc theo cng mt ng vi lu lng t y ti x (nhng theo chiu ngc li). Mc d cc lung ny c th b chng ln nhau do nhiu tnh nng giao thc nh tuyn, c th hu ch nu iu ny xy ra, c bit trong cc mng nh. Do iu ny, c th s dng cc lung lu lng hai hng d hn cc lung mt hng trong thit k mng ban u. Xc nh cc lung hai chiu cho mng mu c ch ra trong bng 7. Di thng lu lng hai chiu gia Adelaide v Sydney v d c ly 25 Mb/s l ln nht ca di thng mt chiu t Sydney n Adelaide (12.5 Mb/s) v di thng t Adelaide n Sydney (25Mb/s). To cc lung hai chiu theo cch ny s hng ti xc nh lu lng vt qu khng ng k trong mng. iu ny hu ch khi bc xp x u tin thch hp.





Hnh18: V d thit k mng phn b a hnh


Thit k m hnh mng ATM MPLS Bng 6: V d mng - ma trn lu lng mt hng

Bng 7: V d mng Lu lng hai chiu gn ng

5. Thit k cch b tr mng ng trc Cch b tr ng trc s lin quan n nhng vn v: B tr vng a l v d xc nh v tr tt cho cc nt D phng mc mng v d c nhiu ng ti mi ch D phng cc trung k Cch b tr mng la chn trong v d ny c ch ra trong hnh 18(d). C th c nhiu cch b tr khc nhau. Cch b tr m c la chn bao gm s kt hp mng vng ring lin kt cc nt lin k bn ngoi mng v mt mng hnh sao kt ni cc nt tr v mt LSR ATM ph trong li mng. Cch la chn ny cung cp


Thit k m hnh mng ATM MPLS mt mc tt cho d phng mc mng vi t nht hai ng gia mi cp nt. Nt LSR ATM ph c t Bourke, mt thnh ph gn nh cch u bn ca nm PoP khch hng. Vi mc tt cho mc d phng mc mng, cch b tr ny khng cn thit phi c cc trung k d phng, bi v n c th nh tuyn li cc VC nhn MPLS. Trong v d ny, hu ht cc trung k c chn khng d tha i vi h thng kinh t. Mt cp trung k d phng c s dng cho cc ng lin kt c mong i s dng nhiu nht, l gia Sydney v Melbourne. 6. Xc nh cc lung lin kt da trn c lng lu lng Vn ny lin quan n vic tnh ton cc ng c thc hin bi lu lng thng qua mng ng trc. Vi cc giao thc nh tuyn nh OSPF, l th tc khng phc tp nh lu lng IP s theo ng c bc nhy ngn nht (minimum- hop path) tr khi gi qun tr c s dng. Ni c hai hay ba ng c bc nhy ngn nht lu lng s gn nh cn bng qua chng. Qu trnh tnh lung lin kt cho lu lng trong bng 7 c ch ra trong hnh 19(a), v tng s c ch ra trong hnh 19(b). 7. nh dung lng kt ni Da trn s xc nh cc lung lin kt, dung lng kt ni c th c nh ra cho cc ng lin kt trong mng. iu ny ni chung thng lin quan ti vic chn kch thc ng kt ni chun tip theo (T3/E3, STM-1, v.v) ln hn cc lung lin kt va tnh ton. Vn ny c minh ho trong hnh 19(c).



Hnh 19: V d thit k mng Tnh ton bng thng lin kt 8. iu chnh mc d phng Ti ni trung k d phng khng c s dng v mng da vo nh tuyn li p ng tin cy, th c th cn thit phi iu chnh bng thng lin kt m bo dung lng chng li cc ng lin kt h hng . V d, nu ng lin kt nhn r trong hnh 19(c) hng th cc ng lin kt s v t s cn mang mt vi hay tt c lu lng ca n. Ti cc ng lin kt ny c th sau vt qua tc E3, vy mt ng lin kt STM-1 (hay nhiu ng E3) c th c yu cu cho mi ng lin kt s v t. Tung t, nu lin kt u hng th lin kt v c th yu cu hn dung lng E3. Cng vy, nu lin kt y hng th ti c yu cu cho


Thit k m hnh mng ATM MPLS lin kt w c th vt qu E3. Bi vy, phn phi cc di thng lin kt cui cng c th hin trong hnh 19(d). 9. Kim tra cc thit b c la chn c ph hp khng Vn ny lin quan n vic kim tra trong bng 4 v bng 5 cc thit b PoP c la chn c th h tr s lng v kch thc ca cc ng lin kt c la chn trong thit k mng. Mng trong trng hp ny c th vt qua cc bc kim tra nhng trong v d cho thy PoP Melbourne s dng MGX 8850 thay cho BPX 8680. PoP ny cn hai hai ng lin kt STM-4 v hai ng lin kt STM-1 khng h tr trn MGX 8850. Vy trong v d mang tnh gi thit ny, PoP cn thit k li v d bng cch s dng BPX 8680 thay v MGX 8850. Lu rng bt k thit k li nu c yu cu l mt vn tng i nh. Nhiu kiu thit b Cisco khc nhau c th c s dng trong cc PoP MPLS ATM v n thng c nhn thy rng mt PoP c th xy dng p ng cc yu cu ca mt v tr n gin bng cch s dng kt hp cc thit b c s dng ti cc v tr khc. Mt BPX 8680 v d kt hp vi vi gi (shelves) MGX 8850. Lu trn cc cp ng lin kt ATM d phng C ba cch chnh hon thnh vic thay i cho mt cp ng lin kt ATM d phng: Thay i mc lin kt d liu y l k thut d phng lin kt thng thng trong cc mng ATM truyn thng. Vic thay i xy ra do kim tra lp lin kt d liu v vt l trong chuyn mch ATM hay phn cng LSR ATM. Phn cng chuyn mch cng thng thit lp bn sao ca tt c cc trng thi mch o trn lin kt d tr. Trong chuyn mch vi d phng mc lin kt d liu, bt c lin kt n sai hng s thng dn n kt qu gn nh d liu mt bng khng trn bt k mch o. Thm vo , nh tuyn v lp mng (IP hay PNNI, v.v) s khng b nh hng bi vn hng ng lin kt, hoc ngay c c cnh bo rng n va xy ra. Tuy nhin vi d phng lin kt d liu, lin kt d tr khng c gi tr mang d liu ngoi tr trng hp lin kt chnh hng. Da vo cch n c lp t, chuyn mch bo v t ng (APS) c th l mt hnh thc d phng lin kt d liu. Trn MGX 8850 v BPX 8650, chuyn i APS SONET dn n khng thay i giao din nh c nhn bi nh tuyn kt ni, v khng mt trng thi kt ni.


Thit k m hnh mng ATM MPLS Hp knh o trn ATM (IMA)- IMA mang d liu trn mt nhm cc lin kt bng cch phn phi t bo qua cc lin kt trong kiu lun chuyn theo vng (round-robin) N cung cp c hai mc d liu phn chia qua lin kt v d phng. Nu mt ng lin kt trong nhm hng, cc t bo khng c gi trn lin kt , nhng cc lin kt khc vn s dng. IMA ch nn dng cho lin kt tc thpnhm lin kt T1 hay E1. Lin kt song song vi thay i lp mng trong trng hp ny cp trung k d phng c s dng vic bo v lp d liu khng c s dng tt c v tt c chuyn i kt ni din ra ti lp mng. nh tuyn IP hay PNNI cnh bo vi tt c lin kt hng v tc ng li chng. iu ny khng c bit tt cho lu lng hng kt ni nhng lm vic tt vi nh tuyn IP v MPLS. Vi OSPF nhiu ng tn hao nh nhau (equal-cost-multipath) hay tng t, OSPF s chn lu lng cn bng cho mi nh tuyn ngang qua lin kt trong mt cp lin kt. iu ny dn ti mt cp LVC nhn MPLS c thit lp cho mi ch trn mi lin kt. Nu mt trong cc lin kt hng, nh tuyn IP s phn pht lu lngtrn cc lin kt cn li thit lp cc LVC. Nu hp nht VC c s dng, iu ny s khng yu cu bo hiu MPLS v c th hon thnh trong mt giy hay n nh vy. Tin b trong phng thc ny l n cho php di thng trong trung k d phng c s dng, cho php lu lng hiu qu tt nht c mang trong mng. Lin kt d phng c yu cu, cc khuyn ngh cho s dng cch thc ny l nh sau: Cc mng IP+ATM - Mng IP+ATM ny c th s dng ghp knh o vi d phng cho cc trung k tc thp v cch khc s dng d phng lp lin kt d liu. iu ny trnh nh tuyn li nhiu ln ca lu lng nh hng kt ni Mng MPLS ATM thun tu Thm mt ln na mng ny nn s dng ghp knh o vi d phng cho cc trung k tc thp. Cch khc, nu mng s dng kt hp VC cc lin kt song song vi chuyn i lp mng c th c s dng to nn dung lng mng y c gi tr s dng. Cui cng, nu kt hp VC l khng th, d phng lp lin kt d liu nn c s dng.





Hnh 20: Quan im v mng MPLS ATM

3.3.3 nh tuyn IP trong mng MPLSMPLS s dng cc giao thc nh tuyn IP thng thng OSPF, IS-IS, v.v - xc nh cc b nh tuyn cho lu lng IP, v t quyt nh cc b nh tuyn cho cc LVC. Mi LSR hot ng theo cc giao thc nh tuyn IP trong cng mt cch m cc b nh tuyn IP hot ng. Mt lin h quan trng ca s dng giao thc ny l OSPF (hay IS-IS, v.v) thy trong mt mng MPLS, chnh xc ging nh b nh tuyn mng thng thng. iu ny c gii thch trong hnh 20. C th c nhiu quan im v mng MPLS ATM: Quan im vt l - Quan im ny cho bit cc ng lin kt v cc thit b trong mng v mt vt l. Mt v d c th hin trong hnh 20(a) Quan im chc nng Khi mt sn phm c mt vi chc nng, cc chc nng ny cs th c th hin tch bit. Thng hu ch khi xem chc nng b iu khin chuyn mch nhn (LSC) trong mt LSR ATM nh ring bit vi chc nng chuyn mch. V d, MGX 8850 trong hnh 20 bao gm mt LSR bin ring v mt LSC c th hin mt cch ring bit. Hn na, th

Do an ATM-MPLS Cua LuongThiThao

Documents