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IP:c u im l: thit k ca n linh hot trong vic m rng mng nhng c nhc im l: chuyn mch gi tin i chm hn (do n x l ti layer 3), ng thi QoS ca n th thp, kh khn trong vic iu khin lu lng. - ATM: l mt connection-oriented, tc l khi to knh truyn trc sau cc cells s i trn con ng ny n ch. ATM l truyn tt c thng tin dng cc gi nh, c kch thc c nh l 53 bytes (trong 5 bytes l header v 48 bytes l payload). u im: tc chuyn mch cao. Nhc im: -H thng thit k ca ATM cng knh phc tp,kh khn trong vic qun l. -Do trong mng ATM yu cu kt ni theo dng full mesh nn kh khn trong vic m rng mng. V vy ngi ta c mun kt hp u im gia hai cng ngh ny li,v l kt qu ca cng ngh MPLS, kt hp tc chuyn mch nhanh ca ATM v kh nng linh hot khi m rng mng ca IP. *************************************************

ATM khc vi k thut nh tuyn IP nhiu im. ATM l mt k thut kt ni c hng tc l hai h thng phi thit lp ng truyn trc khi din ra qu trnh truyn d liu. ATM yu cu cc kt ni c thit lp bng nhn cng hay c thit lp ng bi cc giao thc bo hiu. Mt im khc nhau na l ATM khng thc hin nh tuyn theo tng gi ti mi node trung gian (cch m IP thc hin) m ng dn ATM qua mng gia hai thc th phi c tnh ton t trc v c nh trong thi gian lin lc. Khi thit lp kt ni, mi chuyn mch ATM gn mt gi tr nhn dng hay mt nhn cho chuyn mch, kt ni v cc cng ra/vo ca chuyn mch. K thut ny cho php h thng dnh ring ti nguyn c nh cho mt ng kt ni c th v mi chuyn mch ATM ring cn thit phi xy dng mt bng chuyn tip ch bao gm cc thc th v cc kt ni ang hot ng qua chuyn mch. Ngc li, vi IP mt b nh tuyn phi s dng mt bng nh tuyn cha tt c cc ch n c th caca, trong s ny c nhiu ng a ch m gi tin khng bao gi i qua. Qu trnh chuyn tip mt t bo qua mt chuyn mch ATM tng t nh qu trnh chuyn tip mt gi tin IP qua mt b nh tuyn. C hai u s dng thng tin trong tiu gi (hay t bo) lm kho tm kim trong bng nh tuyn hoc bng chuyn tip tm a ch chng tip theo cho gi tin. Tuy nhin, tc chuyn tip t bo ATM nhanh hn tc chuyn tip gi tin IP rt nhiu ln bi v cc b nh tuyn IP s dng cc giao thc nh

tuyn c thc hin trn c s phn mm v tiu IP c di thay i v ln hn tiu ca t bo ATM nhiu ln. Ngc li tiu ca t bo ATM rt nh v c di c nh, bng chuyn tip cha cc kt ni o nh hn nhiu so vi bng nh tuyn ca IP v vic chuyn tip c thc hin n gin bng cch hon i nhn. Mt c im quan trng lm tng tc chuyn tip ATM ln ng k l c ch chuyn tip ca n c thc hin bng phn cng, iu ny cho php thc hin nhim v mt cch n gin v vi tc cc nhanh. Bng sau so snh cc c im c bn gia IP v ATM. Thuc tnh Hng kt ni Kch c gi tin H tr QoS Khng Thay i Khng IP C Khng i (53B) C Thit lp kt ni trc Kt ni chuyn tip tch cc ni b Nhn c chiu di c nh C ATM

Quyt nh chn ng Theo tng gi tin Trng thi chuyn tip C s chuyn tip Thc hin bo hiu Tt c mng c th S ph hp di nht ca tin t a ch mng Khng

Gii php s dng m hnh xp chng Trong nhng nm gn y, ngnh cng nghip vin thng v ang tm mt phng thc chuyn mch c th phi hp u im ca IP (nh c cu nh tuyn) v ca ATM (nh phng thc chuyn mch). M hnh IP-overATM (IP qua ATM) ca IETF coi IP nh mt lp nm trn lp ATM v nh ngha cc mng con IP trn nn mng ATM. Phng thc tip cn xp chng ny cho php IP v ATM hot ng vi nhau m khng cn thay i giao thc ca chng. Tuy nhin cch ny khng tn dng ht kh nng ca ATM. Ngoi ra cch ny khng thch hp vi mng c nhiu router v khng hiu qu trn mt s mt, chng hn nh c s chng cho v chc nng, qun l mng phc tp. T chc ATM-Forum da trn m hnh ny pht trin cng ngh LANE v MPOA. Cc cng ngh ny s dng cc my ch chuyn i a ch nhng u khng tn dng c kh nng m bo cht lng dch v ca ATM. Chng ta hy xem xt k hn vn ny.

T s so snh IP v ATM trn ta thy mi k thut u c u v nhc im ring. Nhng mt iu chc chn l IP s c mt trong tt c cc mng trong tng lai bi v u im tuyt vi nht ca ca IP l n c th chy trn bt k cng ngh lp lin kt d liu no, k c ATM. Do vy, ATM c xem nh l cng ngh lp 2 mnh m cho IP c th trin khai trn . Khi vic ny thc hin, lc chuyn tip tng chng, phi kt ni ca IP khng b thay i. Thc t IP khng c tng rng, n ang chy trn 1 mng c kh nng dnh trc ti nguyn v rng buc tr. T quan im ATM, mt tp cc giao thc nh a ch, nh tuyn v bo hiu c pht trin cho ATM c th hot ng m khng cn phi thay i. Mt cu hi t ra l: phi lm g kt hp hai k thut ny vi nhau? V cu tr li nm vn phn gi a ch. lin lc vi 1 trm ngang cp khc trong cng mt mng con, mt trm IP ngun cn phn gii a ch IP ca trm ch vi a ch lp 2 tng ng. iu ny cho php trm IP ngun nh a ch cho cc gi tin vi a ch IP ch v sau ng gi gi tin IP vo trong mt khung thng tin lp 2 vi a ch ch lp 2 tng ng. Theo k thut ATM, a ch ATM ch ch c s dng khi chuyn tip yu cu thit lp SVC (knh o bo hiu) trc khi thit lp kt ni. Tuy nhin, trm IP ngun vn cn phn gii a ch a ch IP ch thnh a ch ATM n c th khi to mt kt ni ATM SVC n ch. Quan im ny c th hin nh hnh 1.1. Hnh v minh ho mt trm IP ngun c gn vo mng ATM, n yu cu server phn gii a ch (ARS) phn gii a ch ATM ca trm IP ch. ARS gi a ch ATM ca trm IP ch cho trm IP ngun v sau trm IP thit lp mt SVC n ch.

Server phn Server phn gii a ch gii a ch

Yu cu Tr li

Ngun

SVCATM Network

ch

Hnh 1.1. S dng Server phn gii a ch cho mng ATM IETF ln u tin a ra gii php kt hp IP v ATM trong RFC1577, Classical IP over ATM (CLIP). Trong RFC1577, mt Server phn gii a ch ATM (ATMARP) c nh ngha duy tr mt bng cc a ch IP v ATM. Sau ATM Forum tng qut ho gii php ny phn gii a ch MAC vi a ch ATM v cng b sung chc nng qung b. Mc ch l pht trin mt h thng cho php cc ng dng ca mng LAN c th chy trn mng ATM m khng cn bt c s thay i no. N lc ca h c t tn l m phng LAN (LANE), LANE c ng dng kh ph bin v n cho php cc ng dng LAN a giao thc chy mt cch trong sut trn cc LAN k tha v LANE. C hai gii php trn u tng t nhau ch chng tch hon ton chc nng ca LAN v IP lp mc cao khi lp cc dch v nm bn c h tr bi ATM. Mt im tng t na gia 2 gii php ny l v phm vi ca cc kt ni ATM. CLIP ch hn ch vic truyn thng ATM gia cc Host (hoc Router) trn cng mt mng con IP logic (LIS). Ngay c khi 2 host trn cc mng con khc nhau c kt ni cng mt mng ATM, th vn phi cn 1 router chuyn tip cc gi. iu ny li sinh ra cc thng tin b sung v tr do nh tuyn tng chng. LANE cng c s hn ch tng t, trong 2 host trn cng mt mng ATM nhng khc mng IP logic cng khng th giao tip trc tip bng vic s dng cc kt ni ATM m phi s dng b nh tuyn trao i thng tin. S pht trin tip theo cho php 2 host trn hai mng khc nhau c th lin lc ATM trc tip vi nhau. iu ny yu cu s ni lng m hnh mng ni tip ang tn ti. Gii php ny tip tc h tr nh tuyn tng chng

truyn thng nhng cng cung cp mt phng tin, theo thit b IP ngun c th thit lp mt kt ni ATM trc tip ti thit b IP ch trn mt mng khc. Do , mng c th cung cp mt ng dn vi nh tuyn tng chng thng thng cho cc lung lu lng dung lng nh, n lc ti a v mt ng dn chuyn mch cho lu lng ln, thi gian truyn di. K thut ny c thc hin ln u tin giao thc phn gii chng k tip (NHRP) do IETF a ra, sau n c phi hp cng vi a giao thc ATM trn ATM (MPOA) ca ATM forum. C hai gii php ny m rng c ch Server phn gii a ch c s dng bi CLIP v LANE phn gii a ch bin mng con. Bi vy xut hin mt kiu nh tuyn hiu nng cao mi gi l nh tuyn ng tt (cut through hay shortcut). N b sung cho nh tuyn IP mt dch v phn gii a ch cng vi cc giao thc nh tuyn v bo hiu cn thit qun l cc SVC ng. Khi nim nh tuyn ng tt c minh ho nh hnh 1.2.Data Query Data Query Responsse

Router Router LIS1

Responsse

Router Router LIS3

Data

LIS2

Ngun

Shortcut SVC

ch

Hnh 1.2. Khi nim nh tuyn ng tt

1.3 S ra i cng ngh MPLS1.3.1 Chuyn mch nhn l g?Chuyn mch nhn a giao thc (MPLS) l kt qu ca qu trnh pht trin nhiu gii php chuyn mch IP, c chun ho bi IETF. Tn gi ca n bt ngun t thc t l hon i nhn c s dng nh l k thut chuyn tip nm bn di. S s dng t a giao thc trong tn ca n c ngha l n c th h tr nhiu giao thc lp mng, khng ch ring IP. Ngoi ra cc nh cung cp mng c th cu hnh v chy MPLS trn cc cng ngh lp 2 khc nhau nh PPP, Fram Relay khng ch ring ATM. V mt kin trc iu ny l ng, nhng trong thc t MPLS thng tp trung vo vic vn chuyn cc dch v IP trn ATM.

MPLS l gii php nhm lin kt nh tuyn lp mng v c ch hon i nhn thnh mt gii php n nht t c cc mc tiu sau: Ci thin hiu nng nh tuyn Ci thin tnh mm do ca nh tuyn trn cc m hnh xp chng truyn thng. Tng tnh mm do trong qu trnh a v pht trin cc loi hnh dch v mi. Mng MPLS c kh nng chuyn cc gi tin ti lp 3 bng vic s dng x l tng gi v chuyn tip gi tin ti lp 2 s dng c ch hon i nhn. MPLS da trn m hnh ngang cp, v vy mi mt thit b MPLS chy mt giao thc nh tuyn IP, trao i thng tin nh tuyn vi cc thit b ln cn, v ch duy tr mt khng gian cu hnh mng v mt khng gian a ch. MPLS chia b nh tuyn lm hai phn ring bit: chc nng chuyn gi tin v chc nng iu khin. Phn chc nng chuyn gi tin s dng c ch hon i nhn. K thut hon i nhn v bn cht l vic tm chng k tip ca gi tin trong mt bng chuyn tip nhn, sau thay th gi tr nhn ca gi ri chuyn ra cng ra ca b nh tuyn. Vic ny n gin hn nhiu so vi vic x l gi tin thng thng v do vy ci tin kh nng ca thit b. Cc b nh tuyn s dng thit b ny 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 gia cc LSR, v th tc gn nhn chuyn thng tin nh tuyn thnh bng nh tuyn chuyn mch nhn. MPLS c th hot ng c vi cc giao thc nh tuyn Internet nh OSPF v BGP hay PNNI ca ATM. Khi mt gi tin vo mng MPLS, cc b nh tuyn chuyn mch nhn khng thc hin chuyn tip theo tng gi m thc hin phn loi gi tin vo trong cc lp tng ng chuyn tip FEC, sau cc nhn c nh x vo trong cc FEC. Mt giao thc phn b nhn LDP c xc nh v chc nng ca n l n nh v phn b cc rng buc FEC/nhn cho cc b nh tuyn chuyn mch nhn LSR. Khi LDP hon thnh nhim v ca n, mt ng dn chuyn mch nhn LSP c xy dng t li vo ti li ra. Khi cc gi vo mng, LSR li vo kim tra nhiu trng trong tiu gi xc nh xem gi thuc v FEC no. Nu c mt rng buc nhn/FEC th LSR li vo gn nhn cho gi v nh hng n ti giao din u ra tng ng. Sau gi c

hon i nhn qua mng cho n khi n n LSR li ra, lc nhn b loi b v gi c x l ti lp 3. Hiu nng t c y l nh vic a qu trnh x l lp 3 ti bin ca mng v ch thc hin 1 ln ti thay cho vic x l ti tng node trung gian nh ca IP. Ti cc node trung gian vic x l ch l tm s ph hp gia nhn trong gi v thc th tng ng trong bng kt ni LSR v sau hon i nhn- qu trnh ny thc hin bng phn cng. Mc d hiu nng v hiu qu l 2 kt qu quan trng, song chng khng phi l cc li ch duy nht m MPLS cung cp. Trong mt ca nhng nh cung cp cc mng ln, th kh nng thc hin k thut lu lng tin tin m khng phi tr gi v hiu nng ca MPLS c quan tm c bit.

1.3.2 Ti sao s dng MPLS?Sau y chng ta nu ra cc s c la chn cng ngh MPLS. Tc v tr Chuyn tip da trn IP truyn thng l qu chm x l ti lu lng ln trong mng ton cu (the Internet) hay trong cc lin mng. Thm ch vi cc k thut tng cng, nh l tm kim bng nhanh cho cc datagram no , th ti trn cc router thng nhiu hn lng ti m router c th x l. Dn n kt qu l lu lng v cc kt ni c th b mt v hiu nng ton mng gim st trong mt mng da trn IP. Ngc li vi chuyn tip IP, chuyn mch nhn ang chng t l mt gii php hiu qu gii quyt vn ny. Chuyn mch nhn nhanh hn nhiu bi v gi tr nhn c t header ca gi c s dng truy nhp bng chuyn tip ti router, ngha l nhn c s dng tm kim trong bng. Vic tm kim ny ch yu cu mt ln truy nhp ti bng, khc vi truy nhp bng nh tuyn truyn thng vic tm kim c th cn hng ngn ln truy nhp. Kt qu ca hot ng hiu qu ny l ch lu lng ngi s dng trong gi c gi qua mng nhanh hn nhiu so vi chuyn tip IP truyn thng. Jitter. Vi cc mng my tnh, ngoi cc yu t v: tc v s p ng ca n, tr, cn c mt thnh phn khc, l bin thin tr ca lu lng ngi s dng, n c gy ra bi vic cc gi i qua nhiu node mng trc khi chm ti ch. Ngoi ra s tch lu ca cc tr bin thin khi cc gi to ra

ng i t ngun n ch. Ti mi node, a ch ch trong gi phi c kim tra v so snh vi mt tp di cc a ch ch c th trong bng nh tuyn ca node. Khi gi i qua nhng node ny, n gp phi c tr v bin thin tr, ph thuc vo vic n cn thi gian bao lu tm kim trong bng nh tuyn v tt nhin l ph thuc vo c s cc gi phi c x l trong mt khong thi gian cho trc. Kt qu cui cng l ti node nhn xy ra hin tng bin thin tr, n c l kt qu ca s tch lu bin thin tr ti mi node v gia ngun vi ch. Tnh hung ny l phin h vi cc gi thoi v ngi nghe c th nghe cc cu ni ca ngi ni khng theo ng th t nh ngi ni ni. Mt ln na, hot ng chuyn mch nhn s lm cho lu lng c gi qua mng nhanh hn v bin thin tr t hn so vi hot ng nh tuyn IP truyn thng. Kh nng m rng mng R rng, tc l kha cnh quan trng ca chuyn mch nhn, v x l lu lng nhanh cng rt quan trng. Nhng chuyn mch nhn khng ch cung cp cc dch v tc cao m n cn c th cung cp cho mng kh nng m rng. Kh nng m rng lin quan n kh nng m mt h thng, trong trng hp chng ta quan tm l Internet, c kh nng iu chnh ph hp vi mt lng ln ngi s dng ang tng ln tng ngy. Hng ngn ngi s dng mi v cc node h tr nh l router v server ang c a vo trong mng Internet mi ngy. Chng ta th hnh dung nhim v ca router nu n phi theo kp lng ngi s dng ny. Chuyn mch nhn cung cp cc gii php cho s pht trin nhanh chng v xy dng cc mng ln bng vic cho php mt lng ln cc a ch IP c kt hp vi mt hay vi nhn. Gii php ny gim ng k kch c bng a ch v cho php router h tr nhiu ngi s dng hn. Tnh n gin Mt kha canh hp dn khc ca chuyn mch nhn l ch n l mt giao thc chuyn tip c bn. N n gin n tuyt vi: chuyn tip gi ch da vo nhn. Nhn c xc nhn th no l mt vn khc; ngha l, cc k thut iu khin c thc hin nh th no rng buc nhn vi lu lng ngi s dng l khng lin quan ti hot ng chuyn tip thc s. Nhng k thut iu

khin ny l mt ci g phc tp, nhng chng khng nh hng n hiu qu ca dng lu lng ngi s dng. Ti sao khi nim ny li quan trng? N c ngha rng nhiu phng php khc nhau c th c s dng thit lp cc rng buc nhn vi lu lng ngi s dng. Nhng sau khi rng buc c thc hin, cc hot ng chuyn mch nhn chuyn tip lu lng l n gin. Cc hot ng chuyn mch nhn c th c thc hin bng phn mm, bng cc mch tch hp chuyn dung, hay bng cc b x l c bit. S dng ti nguyn Cc k thut iu khin thit lp nhn khng c l gnh nng cho mng. Chng khng nn tiu tn nhiu ti nguyn. Nu chng lm nh vy, th li ch ca n b ph nhn. May mn thay, cc mng chuyn mch nhn khng cn nhiu ti nguyn mng thc hin cc cng c iu khin trong vic thit lp cc ng i chuyn mch nhn cho lu lng ngi s dng (nu chng tiu tn nhiu ti nguyn th l do chng c thit k khng tt). iu khin ng i Tr mt s ngoi l, nh tuyn trong cc lin mng c thc hin bng vic s dng a ch ch IP (hay trong mt LAN l a ch MAC ch). Hin ti cng c nhiu sn phm ang s dng cc thng tin khc, chng hn nh trng kiu dch v IP (TOS) v s cng l mt phn trong vic quyt nh chuyn tip. Nhng nh tuyn da theo a ch ch l phng php chuyn tip ph bin nht trong mng IP.R2 R4

R1 R6

R3

R5

Hnh 1.3. nh tuyn da trn a ch ch

nh tuyn da theo a ch ch khng lun lun l hot ng hiu qu. thy ti sao, chng ta xem xt hnh 1.3. Router 1 nhn lu lng t cc router 2 v router 3. Nu a ch ch IP trong gi IP n l a ch ca router 6, bng nh tuyn ti router 1 s ch o router ny chuyn tip lu lng i theo router 4 hoc router 5. Tr mt s ngoi l, khng c yu t no khc c tnh n y. Chuyn mch nhn cho php cc ng i qua mt lin mng c iu khin tt hn. Chng hn, mt gi tin c dn nhn xut pht t router 2 d nh i n router 6 v mt gi tin nhn khc cng nh i n router 6 nhng xut pht t router 3. Trong mng chuyn mch nhn, cc gi tr nhn khc nhau ca cc gi c th hng dn router 1 gi gi c dn nhn ti router 4 v mt gi vi mt gi tr nhn khc i n router 5 ri sau mi n router 6. Khi nim ny cung cp mt cng c iu khin cc node v cc tuyn x l lu lng hiu qu hn, cng nh a ra cc lp lu lng no vi mc dch v khc nhau (da trn cc yu cu v QoS). C th tuyn gia router 1 v router 4 l DS3; tuyn gia router 1 v router 5 l SONET. Nu ng dng ca ngi s dng cn nhiu bng tn hn, nhn ca ngi s dng c th c dng hng dn router chuyn lu lng vo tuyn SONET ch khng vo tuyn DS3. Gii php da trn chnh sch ny s dng chuyn mch nhn cho mng p ng cc yu cu ca cc lp lu lng - khi nim ny c gi l k thut lu lng (TE). 1. Cng ngh IP u im: n gin, chun ha, mc ph bin rng, c coi l cng ngh ca tng lai. Nhng nghin cu gn y ch ra kh nng s dng IP trc tip trn nn cng ngh quang v nhng sa i giao thc IP m bo cht lng dch v mi to tin cho kh nng chim lnh th trng ca cng ngh ny trong tng lai. Nhc im: Vi nh tuyn IP truyn thng, cht lng dch v ch dng li mc n lc ti a. Khng c kh nng h tr cc dch v thi gian thc nh thoi hay video cht lng cao. c th h tr cc dch v ny cn b sung cc giao thc iu khin cht lng dch v nh RSVP hay chuyn sang IPv6.

2. Cng ngh ATM u im: L cng ngh trong giai on chn mui, c chun ha bi ITU-T v Din n ATM (ATM-forum), c kh nng h tr IP qua ATM nhng ch l s kt hp m cha phi l s tch hp IP v ATM. Nhc im: Gi thnh cao, giao thc iu khin (MPOA) phc tp hn so vi IP truyn thng. Vic to thm mt lp ATM ca cc ng dng IP s lm hn ch rt nhiu kh nng ca IP. 3. Cng ngh MPLS u im: n gin, tch hp nh tuyn v chuyn mch, iu khin nh tuyn trn nn tng IP, chuyn mch trn nn ATM, h tr cht lng dch v chp nhn c (cao hn DiffServ, thp hn ATM). Gi thnh hp l. Nhc im: Gi thnh cao hn IP truyn thng, thp hn ATM, chun ha ang trong giai on tip tc pht trin. Theo d kin, qu trnh pht trin ca giao thc trong mng li c d bo nh sau: Giai on 2003-2005: IP/MPLS qua SONET/SDH sang cp quang Giai on sau 2005: IP/MPLS qua cp quang trc tip

im vt tri ca MPLS so vi m hnh IP over ATM: - Khi hp nht vi chuyn mch ATM, chuyn mch nhn tn dng nhng thun li ca cc t bo ATM - chiu di thch hp v chuyn vi tc cao. Trong mng a dch v chuyn mch nhn cho php chuyn mch BPX/MGX nhm cung cp dch v ATM, Frame, Replay v IP Internet trn mt mt phng n trong mt ng i tc cao. Cc mt phng (Platform) cng cng h tr cc dch v ny tit kim chi ph v n gin ha hot ng cho nh cung cp a dch v. ISP s dng chuyn mch ATM trong mng li, chuyn mch nhn gip cc cc dng Cisco, BPX8600, MGX8800, Router chuyn mch a dch v 8540 v cc chuyn mch Cisco ATM gip qun l mng hiu qu hn xp chng (overlay) lp IP trn mng ATM. Chuyn mch nhn trnh nhng rc ri gy ra do c nhiu router ngang hng v h tr cu trc phn cp (hierarchical structure) trong mt mng ca ISP. S tch hp: MPLS xc nhp tnh nng ca IP v ATM ch khng xp chng lp IP trn ATM. MPLS gip cho c s h tng ATM thy c nh tuyn IP v loi b cc yu cu nh x gia cc c tnh IP v ATM. MPLS khng cn a ch ATM v k thut nh tuyn (nh PNNI). tin cy cao hn: Vi c s h tng ATM, MPLS c th kt hp hiu qu vi nhiu giao thc nh tuyn IP over ATM thit lp mt mng li (mesh) dch v cng cng gi cc router

xung quanh mt m my ATM. Tuy nhin c nhiu vn xy ra do cc PCV link gia cc router xp chng trn mng ATM. Cu trc mng ATM khng th thy b nh tuyn. Mt link ATM b hng lm hng nhiu router-to-router link, gy kh khn cho lng cp nht thng tin nh tuyn v nhiu tin trnh x l ko theo. Trc tip thc thi cc loi dch v: MPLS s dng hng i v b m ca ATM cung cp nhiu loi dch v khc nhau. N h tr quyn u tin IP v loi dch v (class of service cos) trn chuyn mch ATM m khng cn chuyn i phc tp sang cc lp ATM Forum Service. H tr hiu qu cho Mulicast v RSVP: Khc vi MPLS, xp lp IP trn ATM ny sinh nhiu bt li, c bit trong vic h tr cc dch v IP nh IP muticast v RSVP( Resource Reservation Protocol - RSVP). MPLS h tr cc dch v ny, k tha thi gian v cng vic theo cc chun v khuyn khch to nn nh x xp x ca cc c trng IP&ATM S o lng v qun l VPN: MPLS c th tnh c cc dch v IP VPN v rt d qun l cc dch v VPN quan trng cung cp cc mng IP ring trong c s h tng ca n. Khi mt ISP cung cp dch v VPN h tr nhiu VPN ring trn mt c s h tng n.Vi mt ng trc MPLS, thng tin VPN ch c x l ti mt im ra vo. Cc gi mang nhn MPLS i qua mt ng trc v n im ra ng ca n. Kt hp MPLS vi MPBGP (Mutiprotocol Broder Gateway Protocol) to ra cc dch v VNP da trn nn MPLS (MPLS-based VNP) d qun l hn vi s iu hnh chuyn tip qun l pha VNP v cc thnh vin VNP, dch v MPSL-based VNP cn c th m rng h tr hng trm nghn VPN. Gim ti trn mng li: Cc dch v VPN hng dn cch MPLS h tr mi thng tin nh tuyn phn cp. Hn na,c th tch ri cc nh tuyn Internet khi li mng cung cp dch v. Ging nh d liu VPN, MPSL ch cho php truy sut bng nh tuyn Internet ti im ra vo ca mng. Vi MPSL, k thut lu lng truyn bin ca AS c gn nhn lin kt vi im tng ng. S tch ri ca nh tuyn ni khi nh tuyn Internet y cng gip hn ch li, n nh v tng tnh bo mt Kh nng iu khin lu lng:

MPLS cung cp cc kh nng iu khin lu lng sng dng hiu qu ti nguyn mng. K thut lu lng gip chuyn ti t cc phn qu ti sang cc phn cn ri ca mng da vo im ch, loi lu lng, ti, thi gian,