Bao Cao Mang Vien Thog

BO CO TI

MNG VIN THNG

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LI NI U

Cng vi s pht trin ca cc ngnh in t - tin hc, cng ngh vin thng trong nhng nm va qua pht trin rt mnh m cung cp ngy cng nhiu cc loi hnh dch v mi a dng, an ton, v cht lng cao p ng ngy cng tt hn yu cu ca khch hng.

Trong xu hng pht trin v hi t ca vin thng v tin hc, cng vi s pht trin nhanh chng v nhu cu ca ngi dng i vi nhng dch v a phng tin cht lng cao lm cho c s h tng thng tin v vin thng c nhng thay i ln v c bn. Nhng tng i chuyn mch knh truyn thng khng cn c th p ng nhng i hi ca ngi dng v nhng dch v tc cao, chnh v th i hi cn phi c mt gii php p ng c yu cu . Xu hng vin thng da trn nn tng chuyn mch gi tc cao, dung lng ln v hi t c cc loi dch v trn cng mt h tng l iu tt yu.

Mng th h sau NGN ra i n c pht trin t tt c cc mng c ln. NGN c kh nng lm nn tng cho vic trin khai nhiu loi hnh dch v mi trong tng lai mt cc nhanh chng, khng phn bit ranh gii cc nh cung cp dch v (dch v c lp vi h tng mng). Tuy nhin s pht trin nhanh chng v m rng khng ngng ca Internet, s phc tp ca cc loi hnh dch v dn lm cho mng vin thng hin ti kh p ng c. S ra i ca cng ngh chuyn mch nhn a giao thc MPLS l mt la chn cho cu trc mng trong tng lai bi tnh linh hot ca b nh tuyn v nng lc iu khin lu lng ca thit b chuyn mch trong n.

Trong ni dung bi tp ln ny chng em i su vo nghin cu, tm hiu cng ngh chuyn mch nhn a giao thc MPLS trong NGN. Bi lm khng th trnh khi nhng sai st, rt mong c s gp ca thy c v cc bn bi lm c hon chnh hn.

Chng em xin chn thnh cm n!

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MC LC

BO CO TI ....................................................................................................... i

MNG VIN THNG ................................................................................................. i

LI NI U .............................................................................................................. ii

MC LC ................................................................................................................... iii

DANH MC HNH .................................................................................................... v

DANH MC T VIT TT ..................................................................................... vi

CHNG I: TNG QUAN V MNG TH H SAU ........................................... 1

1.1.Khi qut v mng vin thng ........................................................................... 1 1.1.1.Cc khi nim c bn ................................................................................... 1 1.1.2.Cc thnh phn chnh trong mng vin thng ............................................ 1 1.1.3.Mng vin thng tng t v mng vin thng s ...................................... 2

1.2.Mng vin thng th h sau ............................................................................... 3 1.2.1.Khi nim ...................................................................................................... 3 1.2.2.c im ca mng NGN ............................................................................. 3

1.3.Cu trc chc nng ca mng NGN ................................................................. 3 1.3.1.M hnh phn lp chc nng ....................................................................... 3 1.3.2.Chc nng cc lp ........................................................................................ 4

1.3.2.1.Lp truyn dn v truy nhp .................................................................... 4 1.3.2.2.Lp truyn thng ..................................................................................... 5 1.3.2.3.Lp iu khin ......................................................................................... 5 1.3.2.4.Lp ng dng .......................................................................................... 5 1.3.2.5.Lp qun l .............................................................................................. 5

1.4.Cc cng ngh lm nn tng cho NGN .............................................................. 6 1.4.1.IP ................................................................................................................... 6 1.4.2.ATM .............................................................................................................. 6 1.4.3.IP Over ATM ................................................................................................. 7 1.4.4.MPLS ............................................................................................................ 7

CHNG II: K THUT CHUYN MCH NHN A GIAO THC TRONG MNG TH H SAU .................................................................................................. 8

2.1.S ra i ca cng ngh MPLS ......................................................................... 8 2.1.1.Khi nim v chuyn mch nhn a giao thc ............................................ 8 2.1.2.S cn thit phi s dng MPLS ................................................................. 8

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2.2.c tnh c bn ca MPLS ................................................................................ 9 2.3.Cc thnh phn c bn ca MPLS .................................................................. 10

2.1.3.Thnh phn chuyn tip ca MPLS ........................................................... 10 Thnh phn chuyn tip dng nhn cha trong mt gi tin v thng tin ly t bng thng tin nhn LIB (Label Information base) ca tng thit b LSR chuyn tip gi tin. ............................................................................................ 10 2.1.3.1.Nhn v ngn xp nhn ......................................................................... 10 2.1.3.2. B nh tuyn chuyn mch nhn ........................................................ 11 2.1.3.3.Bng chuyn mch chuyn tip nhn .................................................... 11 2.1.3.4.Lp chuyn tip tng ng FEC ........................................................ 11 2.1.3.5.Bng c s d liu nhn ....................................................................... 12

2.1.4. Thnh phn iu khin MPLS .................................................................. 12 2.1.4.1.Cc phng php iu khin gn nhn ................................................. 12 2.1.4.2.Phn b thng tin iu khin gn nhn ................................................. 13 2.1.4.3.Thit lp ng chuyn mch nhn LSP ............................................... 13

CHNG III: CHUYN MCH A GIAO THC TRONG MNG TH H SAU ............................................................................................................................. 15

3.1. Nhng vn c bn ca cng ngh MPLS .................................................. 15 3.2. Nguyn tc chuyn mch nhn a giao thc ................................................. 15 3.3. Cc giao thc c bn ca MPLS .................................................................... 17

3.3.1. Giao thc phn b nhn LDP ................................................................... 17 3.3.1.1. Khi qut v giao thc phn b nhn LDP ........................................... 17 3.3.1.2. Phng thc phn b nhn ca LDP ................................................... 18 3.3.1.3. Phng thc duy tr nhn .................................................................... 18

3.3.2. Giao thc phn b nhn da trn nh tuyn rng buc CR - LDP ........ 19 3.4. Phn b nhn da trn giao thc dnh trc ti nguyn RSVP ................. 20 3.5. u im nhc im ca MPLS trong mng NGN ...................................... 21

3.5.1. u im ...................................................................................................... 21 3.5.2. Nhc im ................................................................................................ 22

3.6. ng dng MPLS trong mng NGN ................................................................ 22 KT LUN ................................................................................................................. 25

TI LIU THAM KHO ......................................................................................... 26

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DANH MC HNH

Hnh 1.1 Cu trc mng phn cp .............................................................................. 1

Hnh 1.2 Cc thnh phn ca mng vin thng ......................................................... 2

Hnh 1.3 Cu trc mng th h sau (gc mng) ................................................... 4

Hnh 1.4 Cu trc mng th h sau (gc dch v) ................................................. 4

Hnh 2.1. MPLS v m hnh tham chiu OSI ............................................................ 8

Hnh 2.2. Cu trc nhn MPLS ............................................................................... 10

Hnh 2.3. Cu trc ngn xp nhn ............................................................................ 11

Hnh 2.4. Minh ha lp chuyn tip tng ng ................................................... 12

Hnh 2.5. Cu trc thnh phn iu khin ............................................................... 12

Hnh 2.6. iu khin thng tin gn nhn ................................................................. 13

Hnh 3.1. Hot ng chuyn gi tin qua mng MPLS ............................................. 16

Hnh 3.2. S dng RSVP phn b nhn .............................................................. 21

GVHD: Trang v

DANH MC T VIT TT

ATM Asynchronous Transfer Mode Phng thc truyn ti khng ng b

API Application Programming Interface

Giao din lp trnh ng dng

ARP Address Resolution Protocol Giao thc phn tch a chCoS Class of Service Lp dch vFEC Forward Equivalent Class Lp chuyn tip tng ngFIB Forward Information Base C s thng tin chuyn tipICMP Internet Control Message

ProtocolGiao thc iu khin bn tin

IP Internet Protocol Giao thc InternetITU International

Telecommunication UnionLin minh vin thng quc t

LAN Local Area Network Mng cc bLDP Label Distribution Protocol Giao thc phn phi nhnLER Label Edge Router B nh tuyn binLFIB Label Forwarding

Information BaseC s thng tin chuyn tip nhn

LIB Lable Information Base Bng c s d liu nhnLSFT Lable Switch Forwarding

TableBng chuyn tip tng ng nhn

LSP Label Switched Path ng chuyn mch nhnLSR Label Switch Router B nh tuyn chuyn mch nhnMGW Media Gateway Cng phng tinMPLS Multi Protocol Label Switch Chuyn mch nhn a giao thcNGN Next Generation Network Mng th h sauNHRP Next Hop Resolution

ProtocolGiao thc phn gii chng tip theo

OSI Open Systems Interconnection

Kt ni cc h thng m

OSPF Open Shortest Path Fiest ng ngn nht m u tinPNNI Private Network to Network

InterfaceGiao din mng mng ring

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PSTN Public Switched Telephone Network

Mng in thoi chuyn mch cng cng

QoS Quality of Service Cht lng dch vRSVP Resource Reservacation

ProtocolGiao thc dnh trc ti nguyn

TDM Time Division Multiplex Ghp knh phn chia theo thi gian

TCP Transport Control Protocol Giao thc iu khin truyn tiTLV Type/ Length/ Value Cc tham s kiu/ di/ gi trTMN Telecommunication

Management NetworkMng qun l vin thng

VPN Virtual Private Network Mng ring o

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CHNG I: TNG QUAN V MNG TH H SAU

1.1. Khi qut v mng vin thng

1.1.1. Cc khi nim c bn

Mng vin thng l phng tin truyn thng a thng tin t u pht ti u thu. Mng c nhim v cung cp cc dch v cho khch hng.

Mng vin thng cng c th c nh ngha nh sau: mng vin thng l mt h thng gm cc nt chuyn mch c ni vi nhau bng cc ng truyn dn. Nt c phn thnh nhiu cp v kt hp vi cc ng truyn to thnh cc cp mng khc nhau.

Hnh 1.1 Cu trc mng phn cp

Trong mng hin nay gm 5 nt:

Nt cp 1: Trung tm chuyn mch qu giang quc t.

Nt cp 2: Trung tm chuyn mch qu giang ng di.

Nt cp 3: Trung tm chuyn mch qu giang ni ht.

Nt cp 4: Trung tm chuyn mch ni ht.

Nt cp 5: Trung tm chuyn mch t xa.

1.1.2. Cc thnh phn chnh trong mng vin thng

Xt trn quan im phn cng, mng vin thng bao gm cc thit b u cui, thit b chuyn mch v thit b truyn dn.

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Hnh 1.2 Cc thnh phn ca mng vin thng

Thit b u cui:

Thit b u cui l cc trang thit b ca ngi s dng dng giao tip vi mng cung cp dch v. Hin nay c nhiu chng loi thit b u cui ca nhiu hng khc nhau ty thuc vo tng dch v (nh my in thoi, my fax, my tnh c nhn).

Thit b u cui thc hin chc nng chuyn i thng tin cn trao i thnh tn hiu in v ngc li.

Thit b chuyn mch

Thit b chuyn mch l cc nt ca mng vin thng c chc nng thit lp ng truyn gia cc thu bao (u cui). Trong mng in thoi, thit b chuyn mch l cc tng i in thoi.

Thit b truyn dn

Thit b truyn dn c s dng ni cc thit b u cui hay gia cc tng i vi nhau v truyn cc tn hiu mt cch nhanh chng v chnh xc.

Da vo mi trng truyn dn thit b truyn dn c th phn thnh hai loi: v tuyn (cp kim loi, cp quang) v hu tuyn (s dng khng gian lm mi trng truyn dn).

1.1.3. Mng vin thng tng t v mng vin thng s

Mng vin thng c gi l tng t nu c cc c im sau y:

Tn hiu truyn trn trung k l tng t.

Tn hiu truyn trn ng dy thu bao l tng t.

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Cc nt mng x l tn hiu tng t.

Mng vin thng c gi l s nu c nhng c im sau:

Tn hiu truyn trn trung k l s.

Tn hiu truyn trn ng dy thu bao l tng t hoc c th l s vi mng hon ton s.

Cc nt mng x l tn hiu s.

1.2. Mng vin thng th h sau

1.2.1. Khi nim

Mng vin thng th h mi c nhiu tn gi khc nhau, chng hn nh:

- Mng a dch v (cung cp nhiu loi dch v khc nhau)

- Mng hi t (h tr cho c lu lng thoi v d liu, cu trc mng hi t)

- Mng phn phi (phn phi tnh thng minh cho mi phn t trong mng)

- Mng nhiu lp (mng c phn phi ra nhiu lp mng c chc nng c lp nhng h tr nhau thay v mt khi thng nht nh trong mng TDM).

Cho ti nay cc t chc v cc nh cung cp thit b vin thng trn th gii rt quan tm n NGN (Next Generation Network) nhng vn cha c mt nh ngha r rng. Do vy ta ch c th tm nh ngha NGN nh sau:

NGN l mng c h tng thng tin duy nht da trn cng ngh chuyn mch gi, trin khai cc dch v mt cch a dng v nhanh chng, l s hi t gia thoi v d liu, gia c nh v di ng.

1.2.2. c im ca mng NGN

+ Nn tng l h thng m.

+ NGN l do mng dch v thc y nhng cc dch v trn NGN phi c lp vi mng li.

+ NGN l mng chuyn mch gi da trn mt giao thc thng nht.

+ L mng c dung lng ngy cng tng, c tnh thch ng ngy cng tng v c dung lng p ng nhu cu.

1.3. Cu trc chc nng ca mng NGN

1.3.1. M hnh phn lp chc nng

Nhn chung NGN vn l mt xu hng mi m do vy cha c mt khuyn

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ngh chnh thc no c cng b r rng lm tiu chun v cu trc NGN, song da vo m hnh m mt s t chc v cc hng xy dng ta c th tm hiu cu trc NGN chc nng nh sau:

- Lp kt ni (truy nhp v truyn dn/ phn li)

- Lp trung gian hay lp truyn thng (Media)

- Lp iu khin

- Lp qun l

Trong cc lp trn, lp iu khin hin nay rt phc tp vi nhiu loi giao thc, kh nng tng thch gia cc thit b ca cc hng l vn ang c cc nh khai thc quan tm.

Hnh 1.3 Cu trc mng th h sau (gc mng)

Xt t gc kinh doanh v cung cp dch v th m hnh cu trc NGN c thm lp ng dng dch v.

Hnh 1.4 Cu trc mng th h sau (gc dch v)

1.3.2. Chc nng cc lp

1.3.2.1. Lp truyn dn v truy nhp

Phn truyn dn

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Lp truyn ti trong cu trc mng NGN bao gm chc nng truyn dn v chc nng chuyn mch.

Lp truyn dn c kh nng h tr cc mc QoS (Quality of Service) khc nhau

cho cng mt dich v v cho cc dch v khc nhau. N c kh nng lu tr li cc s kin xy ra trn mng (kch thc gi, tc gi, t l mt gi i vi mng chuyn mch gi; bng thng, tr hon i vi mng chuyn mch knh TDM).

Phn truy nhp

Nh tn gi, lp truy nhp cung cp cc kt ni gia thu bao u cui v mng ng trc qua cng giao tip MGW (Media Gateway) thch hp.

1.3.2.2. Lp truyn thng

Lp ny chu trch nhim chuyn i cc loi mi trng (PSTN, LAN, v tuyn) sang mi trng truyn dn gi c p dng trn mng li v ngc li.

Nh , cc nt chuyn mch v cc h thng truyn dn s thc hin chc nng chuyn mch, nh tuyn cuc gi gia cc thu bao ca lp truy nhp di s iu khin ca cc thit b thuc lp iu khin.

1.3.2.3. Lp iu khin

Lp iu khin c nhim v kt ni cung cp cc dch v truyn thng sut t u cui n u cui vi bt k loi giao thc v bo hiu no. Cc chc nng qun l v chm sc khch hng cng c tch hp trong lp iu khin. Nh c giao din m nn c s tch bit gia dch v v truyn dn, iu ny cho php cc dch v mi c a vo nhanh chng v d dng.

1.3.2.4. Lp ng dng

Lp ng dng cung cp cc dch v c bng thng khc nhau v nhiu mc . Mt s dch v s thc hin lm ch vic iu khin logic ca chng v truy nhp trc tip ti lp ng dng, cn mt s dch v khc s thc hin iu khin t lp iu khin. Lp ng dng kt ni vi lp iu khin thng qua giao din m API. Nh m cc nh cung cp dch v c th pht trin cc ng dng v trin khai nhanh chng trn dch v mng.

1.3.2.5. Lp qun l

Lp qun l l mt lp c bit xuyn sut cc lp t kt ni cho n lp ng dng. Ti lp qun l ngi ta c th khai thc hoc xy dng mng gim st vin thng TMN (Telecommunication Management Network) nh mt mng ring theo di

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v iu phi cc thnh phn mng vin thng ang hot ng.

1.4. Cc cng ngh lm nn tng cho NGN

Ngy nay do yu cu ngy cng tng v s lng v cht lng dch v thc y s pht trin nhanh chng ca th trng cng ngh in t - tin hc - vin thng. Nhng xu hng pht trin cng ngh v ang tip cn nhau, an xen ln nhau nhm cho php mng li tho mn tt hn cc nhu cu ca khch hng trong tng lai. Theo ITU c hai xu hng t chc mng chnh:

- Hot ng kt ni nh hng.

- Hot ng khng kt ni.

Tuy vy hai phng thc pht trin ny ang dn tip cn v hi t dn n s ra i ca ca cng ngh ATM/IP. S pht trin mnh m ca cc dch v v cc cng ngh mi tc ng trc tip n s pht trin cu trc mng.

1.4.1. IP

IP (Internet Protocol) l giao thc chuyn tip gi tin. Vic chuyn tip gi tin c thc hin theo c ch phi kt ni. IP nh ngha c cu nh s, c cu chuyn tin, c cu nh tuyn v cc chc nng iu khin mc thp (ICMP). Gi tin IP gm a ch ca bn nhn, a ch l s duy nht trong ton mng v mang y thng tin cn cho vic chuyn gi ti ch.

IP l giao thc chuyn mch c tin cy v kh nng m rng cao. Tuy nhin vic iu khin lu lng rt kh thc hin do phng thc nh tuyn theo tng chng. Mt khc IP cng khng h tr cht lng dch v.

1.4.2. ATM

Cng ngh ATM (Asynchronous Transfer Mode) da trn c s ca phng php chuyn mch gi. Thng tin c nhm vo cc gi tin c di c nh ngn, trong v tr gi khng ph thuc vo ng h ng b v da trn nhu cu bt k ca knh cho trc. Cc chuyn mch ATM cho php hot ng vi nhiu tc v dch v khc nhau. ATM c hai c im quan trng:

- ATM c kh nng nhm mt s knh o thnh mt ng o nhm gip cho cng vic nh tuyn c d dng

- ATM s dng cc gi c kch thc nh v c nh gi l cc t bo ATM. Cc t bo nh vi tc truyn cao s lm cho tr truyn lan v bin ng tr gim nh i vi cc dch v thi gian thc, cng to iu kin cho vic hp knh tc cao d dng hn.

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Qu trnh chuyn giao cc t bo qua tng i ATM cng ging nh chuyn giao gi qua router. Tuy nhin ATM c th chuyn mch nhanh hn v nhn gn trn cell c kch thc c nh v nh hn IP, kch thc bng nh tuyn nh hn nhiu so vi ca IP router. Vic ny thc hin trn cc thit b phn cng chuyn dng nn dung lng tng i ATM thng ln hn dung lng IP router truyn thng.

1.4.3. IP Over ATM

IP over ATM l mt k thut xp chng, n xp IP ln ATM. Giao thc ca hai tng hon ton c lp vi nhau, gia chng phi nh mt loi giao thc na ni thng nh NHRP, ARP. iu hin nay khng c s dng rng ri trong thc t.

1.4.4. MPLS

MPLS l k thut chuyn mch nhn a giao thc. Phng php ny dung hp mt cch hu hiu nng lc iu khin lu lng ca thit b chuyn mch vi tnh linh hot ca b nh tuyn.

MPLS l 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 lng ca mng s c ci thin mt cch r rt.

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CHNG II: K THUT CHUYN MCH NHN A GIAO THC TRONG MNG TH H SAU

2.1. S ra i ca cng ngh MPLS

Chuyn mch nhn a giao thc MPLS l kt qu ca qu trnh pht trin nhiu gii php chuyn mch IP. Tn gi ca n bt ngun t thc t l hon i nhn c s dng nh k thut chuyn tip s dng c ch hon i nhn. S dng t a giao thc c ngha l n c th h tr nhiu giao thc lp mng khng ch ring IP.

2.1.1. Khi nim v chuyn mch nhn a giao thc

Cng ngh chuyn mch nhn a giao thc l kt qu pht trin ca cng ngh chuyn mch IP s dng c ch hon i nhn nh ATM tng tc truyn gi tin m khng cn thay i nh tuyn IP.

Trong chuyn mch nhn, thay v s dng a ch ch quyt nh nh tuyn, mt nhn c gn vo gi tin v c t vo trong tiu gi vi mc ch thay th cho a ch v nhn c s dng chuyn lu lng cc gi tin ti ch.

Hnh 2.1. MPLS v m hnh tham chiu OSI

MPLS l cng ngh kt hp c im tt nht gia nh tuyn lp 3 v chuyn mch lp 2 cho php truyn ti cc gi rt nhanh trong mng li v nh tuyn tt mng bin bng cch da vo nhn.

2.1.2. S cn thit phi s dng MPLS

Tc v tr

Chuyn tip da trn IP truyn thng l qu chm x l ti lu lng ln trong mng ton cu hay trong cc lin kt mng. Dn n kt qu l lu lng v kt ni c th b mt v hiu nng ton mng gim st trong mt mng da trn IP. Trong khi , chuyn mch nhn a giao thc nhanh hn nhiu bi v gi tr nhn c t

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thng tin mo u ca gi c s dng truy nhp bng chuyn tip nh tuyn ti router. Vic tm kim ny ch yu cu mt ln truy nhp ti bng nn lu lng ngi s dng trong gi c gi qua mng nhanh hn nhiu so vi s dng chuyn tip IP truyn thng.

Bin ng tr

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

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 vi nhn. Gii php ny lm gim ng k kch c bng a ch v cho php router h tr nhiu ngi s dng hn.

S dng ti nguyn

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.

Tnh n gin

Mt kha cnh khc ca chuyn mch nhn l s n gin trong cc giao thc chuyn tip gi tin, v nguyn tc rt n gin: chuyn tip gi tin da trn nhn ca n.

iu khin nh tuyn.

Chuyn mch nhn cho php cc b nh tuyn chn tuyn u ra tng minh theo nhn, nh vy c ch ny cung cp mt cch thc truyn ti lu lng qua cc nt v lin kt ph hp vi lu lng truyn ti, cng nh l t ra cc lp lu lng gm cc dch v khc nhau (da trn yu cu QoS) trn . Chuyn mch nhn l mt gii php tt hng lu lng qua mt ng dn, m khng nht thit phi nhn ton b thng tin t giao thc nh tuyn IP ng da trn a ch ch.

2.2. c tnh c bn ca MPLS

K thut lu lng: Cung cp kh nng thit lp ng truyn m lu lng s

truyn qua mng v kh nng thit lp cc cht lng cho cc lp dch v CoS (Class of Service) v cht lng dch v QoS khc nhau.

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Cung cp dch v IP da trn cc mng ring o VPN (Virtual Private Network): Thng qua mng MPLS, cc nh cung cp dch v c th to ra cc ng hm IP i qua mng trong sut i vi dch v ngi s dng.

Loi b cu hnh a lp: S pht trin ca cc cng ngh v dch v trn nn IP to ra rt nhiu cc m hnh xp chng. MPLS l mt gii php thay th cho m hnh xp chng IP trn nn ATM cng nh cc h tng lp 2 khc.

Tuyn hin: Mt c im ni tri ca MPLS l cho php thit lp cc ng nh tuyn tng minh v ng i trn mng.

H tr a lin kt v a giao thc: Thnh phn chuyn tip mch nhn khng mc nh vi bt k mt lp no. c coi l lp trung gian gia lp 2 v 3 (lp 2.5).

2.3. Cc thnh phn c bn ca MPLS

2.1.3. Thnh phn chuyn tip ca MPLS

Mt phng chuyn tip c trch nhim chuyn gi tin da trn gi tr cha trong nhn. Mt phng chuyn tip s dng mt c s thng tin chuyn tip nhn LFIB (Label Forwading Information Base) chuyn tip cc gi.

Thnh phn chuyn tip dng nhn cha trong mt gi tin v thng tin ly t bng thng tin nhn LIB (Label Information base) ca tng thit b LSR chuyn tip gi tin.

2.1.3.1. Nhn v ngn xp nhn

Nhn

Cu trc ca nhn c trnh by trong hnh sau:

Hnh 2.2. Cu trc nhn MPLS

Nhn l mt thc th ngn gn c di c nh v khng c cu trc bn trong, nhn mang gi tr bng s c tha thun bi cc nt MPLS ch th cho kt ni dc theo cc ng chuyn mch nhn LSP. Nhn c gn vo mt gi tin c th i din cho mt lp chuyn tip tng ng.

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Nhn c tng di l 4 byte nm gia tiu lp 2 v tiu IP trong cc gi tin. Cc trng chc nng gm c: gi tr ca nhn th hin bng s (20 bit), trng th hin lp dch v CoS (3 bit), trng ngn xp h tr th bc nhn trong chng nhn (1 bit) v trng thi gian sng ca gi tin (8 bit).

Ngn xp nhn

Hnh 2.3. Cu trc ngn xp nhn

Ngn xp nhn c cu trc bi mt tp cc nhn chn vo gia tiu lp 2 v tiu lp 3 ca gi tin. Nhn nm ti nh ca ngn xp nhn c s dng cho nhim v chuyn tip gi tin, v nhn cui ngn xp c gi tr bit S bng 1. Thng qua ngn xp nhn, MPLS thc hin vic nh tuyn phn cp v to ra cc ng hm chuyn mch nhn.

2.1.3.2. B nh tuyn chuyn mch nhn

LSR l thit b s dng trong mng MPLS chuyn cc gi tin bng th tc phn phi nhn. C mt s loi LSR c bn nh: LSR bin, LSB li, ATM LSR

2.1.3.3. Bng chuyn mch chuyn tip nhn

LSFT (Lable Switch Forwarding Table) l bng chuyn tip nhn c cha thng tin v nhn u vo, nhn u ra, giao din u ra v a ch bc nhy tip theo.

2.1.3.4. Lp chuyn tip tng ng FEC

Lp chuyn tip tng ng FEC (Forward Equivalent Class) l khi nim c dng ch mt nhm cc gi c x l nh nhau qua mng MPLS ngay c khi c s khc bit gia cc gi tin ny th hin trong tiu lp mng.

Mt nhm gi tin IP c th chuyn trn cng mt ng LSP vi cng tiu nhn.

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Hnh 2.4. Minh ha lp chuyn tip tng ng

2.1.3.5. Bng c s d liu nhn

Mi lp chuyn tip tng ng yu cu mt nhn ring bit. LIB l bng lit k cc FEC vi cc nhn tng ng ca chng.

2.1.4. Thnh phn iu khin MPLS

Thnh phn iu khin chuyn mch nhn chu trch nhim phn b thng tin nh tuyn gia cc b nh tuyn chuyn mch nhn. S dng chuyn i cc thng tin nh tuyn thnh c s d liu trong bng chuyn tip. S khc bit ln nht so vi cc kin trc nh tuyn truyn thng l phng php to ra mt bng c s d liu trong thnh phn chuyn tip cha lin kt cc nhn ra vi cc bc nhy k tip.

Hnh 2.5. Cu trc thnh phn iu khin

2.1.4.1. Cc phng php iu khin gn nhn

duy tr bng nh tuyn, thnh phn iu khin thc hin iu khin th tc gn cc nhn vo cc FEC to ra cc lin kt nhn. Thnh phn iu khin cung cp hai kiu gn nhn ti bng chuyn tip l: gn nhn cc b v gn nhn t xa. Kiu gn nhn cc b c thc hin trn chnh b nh tuyn chuyn mch nhn. Kiu gn nhn t xa, lin kt nhn vi cc FEC c iu khin bi b nh tuyn LSR khc.

Thnh phn iu khin chuyn mch nhn s dng c hai kiu gn lin kt nhn xy dng nn bng nh tuyn v c th thc hin theo hai phng php: phng php gn nhn ng xung v phng php gn nhn ng ln.

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Hnh 2.6. iu khin thng tin gn nhn

Trong phng php gn nhn ng xung, cc nhn cc b c s dng gn cho cc lu lng li vo v cc nhn cp pht t xa cho cc lu lng li ra. Mi nhn mang trong gi tin li vo trong mt FEC c to ra theo hng i ca lung lu lng. Tuy nhin, thng tin lin kt nhn li i ngc li t b nh tuyn pha di lung lu lng ti b nh tuyn pha trn.

Phng php gn nhn ng ln i ngc vi phng php ng xung v kha cnh thng tin lu lng gn nhn v cng chiu vi gi tin gn nhn.

2.1.4.2. Phn b thng tin iu khin gn nhn

Khi cc LSR to hoc hy b cc lin kt nhn v FEC, b nh tuyn chuyn mch nhn LSR cn thng tin ti cc LSR khc v lin kt nhn ny. Phn b thng tin iu khin gn nhn c th thc hin theo mt trong hai cch:

- Mang bi cc giao thc nh tuyn: Tip cn ny gn cht qu trnh phn b nhn vo thng tin nh tuyn, v vy thng tin lin kt nhn s gn vi thng tin nh tuyn. iu ny cho php quy trnh xy dng bng chuyn tip c thng nht v thng tin lin kt nhn v thng tin v bc nhy k tip lun cng c yu cu cho mt khon mc trong bng chuyn tip.

- S dng giao thc phn b nhn ring: Tip cn ny c s dng khi cc giao thc nh tuyn khng gii quyt c cc nhc im nu trn. Tuy nhin, nhc im ln nht khi s dng giao thc ny l khng ng b c thng tin v bc nhy k tip v lin kt nhn li ra. Vic trin khai thm giao thc s ko theo phc tp ca h thng tng ln

Nhc im: Cc thng tin nh tuyn c phn b bi cc giao thc nh tuyn c th khng ph hp vi thng tin lin kt nhn. Kh khn trong vic m rng

cc giao thc nh tuyn mang thm thng tin.

2.1.4.3. Thit lp ng chuyn mch nhn LSP

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ng chuyn mch nhn l tuyn to ra t u vo n u ra ca mng MPLS dng chuyn tip gi ca mt FEC no s dng c ch hon i nhn. MPLS cung cp hai c ch thit lp ng dn:

- nh tuyn tng bc/iu khin c lp: Mi b nh tuyn chuyn mch nhn s dng mt giao thc nh tuyn c sn nh OSPF (Open Shortest Path Fiest) hoc PNNI (Private Network to Network Interface) la chn c lp bc nhy k tip cho FEC. Phng php ny cho php thi gian hi t v thi gian thit lp ng chuyn mch nhn nhanh, do qu trnh lin kt nhn c th thit lp v pht hnh t LSR vo bt c thi gian no.

- nh tuyn hin/iu khin theo yu cu: Phng php ny cung cp cc dch v phn bit trn cc lung lu lng theo mc dch v hoc phng php qun l mng. phng php ny cn phi c thi gian ch bn tin truyn ti tt c cc nt dc tuyn m LSP c th thit lp, nhng chnh iu ny li h tr tt cho vn iu khin lu lng v chng vng lp. Hn na, c th tn ti hai ng dn chuyn mch tch bit qua mng m khng nh hng ti cu trc hoc cc vn lin quan n iu hnh trong mng.

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CHNG III: CHUYN MCH A GIAO THC TRONG MNG TH H SAU

3.1. Nhng vn c bn ca cng ngh MPLS

S pht trin nhanh chng cc dch v IP v s bng n ca Internet hin nay dn n mt lot s thay i trong nhn thc cng nh kinh doanh ca cc nh khai thc. Giao thc IP thng tr ton b cc giao thc lp 3. H qu l tt c cc xu hng pht trin u hng vo IP, lu lng ln nht hin nay trn mng trc hu ht u l lu lng IP, dn n cc cng ngh lp di u c xu hng h tr cc dch v IP. Nhu cu th trng cp bch cho mng tc cao v chi ph thp l c s cho mt lot cc cng ngh mi trong c MPLS.

3.2. Nguyn tc chuyn mch nhn a giao thc

Lp chuyn tip tng ng cho mt gi c xc nh bng mt hoc nhiu

tham s do ngi qun tr mng ch nh. C ch chuyn tip ca MPLS c thc hin bng cch tra cu trong mt bng LIB c nh ngha trc (nh x gia cc gi tr nhn v cc a ch ca bc tip theo). Cc gi tin c gi c th cng b nh tuyn bin vo v ra nhng lp chuyn tip tng ng khc nhau. Khi chng c nh nhn khc v c th c vn chuyn qua mng theo cc ng chuyn mch khc nhau.

V c bn, MPLS phn lu lng vo thnh cc loi lp chuyn tip tng ng. Lu lng thuc mt lp chuyn tip tng ng s c chuyn qua mng MPLS theo mt ng chuyn mch nhn. Tng gi d liu s c xem nh thuc mt lp chuyn tip tng ng bng vic s dng cc nhn cc b. Mt b nh tuyn chuyn mch nhn phi bit r ng chuyn mch nhn cho mt lp chuyn tip tng ng, phi dnh mt nhn n cho ng chuyn mch nhn tng ng v phi thng bo nhn cho cc b nh tuyn chuyn mch nhn khc gi gi thuc lp chuyn tip tng ng ny.

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MPLS thc hin bn bc nh hnh sau chuyn gi tin qua mt mng MPLS:

Hnh 3.1. Hot ng chuyn gi tin qua mng MPLS

Bc 1: Bo hiu

Vi bt k loi lu lng no vo mng MPLS, cc b nh tuyn s xc nh mt lin kt gia nhn vi lp chuyn tip tng ng ca lu lng . Sau mi b nh tuyn s to cc mc trong bng c s d liu thng tin nhn LIB. Tip , MPLS thit lp mt ng chuyn mch nhn LSP v cc tham s v cht lng dch v ca ng . thc hin vic ny, cn phi c hai giao thc cho php trao i thng tin gia cc b nh tuyn l:

- Giao thc nh tuyn bn trong mt min trao i cc thng tin v ng i.

- Giao thc phn b nhn.

Giao thc nh tuyn cho php xc nh cu trc cng nh tnh trng hot ng hin thi ca mng. Da vo cc thng tin , mt ng chuyn mch nhn c th gn cho mt lp chuyn tip ng ng. Nh vy, giao thc nh tuyn phi c kh nng thu thp v s dng thng tin h tr cc yu cu cht lng dch v ca lp chuyn tip tng ng.

Cc nhn c gn cho cc gi tng ng vi lp chuyn tip tng ng ca n. V gi tr ca nhn ch mang tnh cc b gia hai b nh tuyn k nhau nn cn phi c c ch m bo tnh xuyn sut gia cc b nh tuyn trn cng mt ng chuyn mch nhn nhm thng nht v vic lit k gi tr nhn vi lp chuyn tip tng ng. Nh vy, cn c mt giao thc phn b nhn gia cc b nh tuyn.

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Bc 2: Dn nhn

Khi mt gi n b nh tuyn bin LER u vo, b nh tuyn u vo sau khi xc nh cc tham s cht lng dch v s phn gi ny vo mt lp chuyn tip tng ng, tng ng vi mt ng chuyn mch no . Sau , b nh tuyn bin LER gn cho gi ny mt nhn ph hp v chuyn tip gi d liu vo trong mng. Nu ng chuyn mch nhn cha c sn th MPLS phi thit lp mt ng chuyn mch mi.

Bc 3: Vn chuyn gi d liu

Sau khi gi vo trong mng MPLS, ti mi b nh tuyn chuyn mch gi d liu s c x l nh sau:

- B nhn cc gi n v gn cho chng mt nhn mi u ra (hon i nhn).

- Chuyn gi d liu n b nh tuyn chuyn mch k tip theo dc ng chuyn mch nhn.

Bc 4: Tch nhn

B nh tuyn bin LER u ra ca min MPLS s ct b nhn, phn tch tiu IP v chuyn tip gi d liu n ch.

3.3. Cc giao thc c bn ca MPLS

3.3.1. Giao thc phn b nhn LDP

3.3.1.1. Khi qut v giao thc phn b nhn LDP

Giao thc phn phi nhn c s dng trong qu trnh gn nhn cho cc gi tin. Giao thc LDP l giao thc iu khin tch bit c cc b nh tuyn chuyn mch nhn s dng trao i v iu phi qu trnh gn nhn trn lp chuyn tip tng ng. Giao thc ny l mt tp hp cc th tc trao i cc bn tin cho php cc LSR s dng cc gi tr nhn thuc lp chuyn tip tng ng nht nh truyn gi tin. Giao thc phn phi nhn LDP c nhng c trng sau:

- LDP chy trn giao thc TCP m bo tin cy ca cc bn tin.

- LDP cung cp cc k thut pht hin LSR cho php LSR tm kim v thit lp truyn thng.

- LDP trao i cc bn tin gia cc LSR bng n v d liu giao thc PDU trong cha i tng TLV. N cho php h tr thm cc chc nng v c tnh mi v to ra tnh tng thch ngc i vi cc giao thc nh tuyn.

GVHD: Trang 17

- LDP c thit k d dng m rng, s dng kiu bn tin c bit thu thp cc i tng m ha TLV (kiu, di, gi tr).

Cc hot ng c bn ca LDP c chia thnh 4 vng sau:

- Pht hin cc LSR ln cn c h tr giao thc LDP.

- Thit lp iu khin gia cc LSR ln cn, m phn cc kh nng v la chn thng tin.

- Pht hnh v thu hi nhn.

3.3.1.2. Phng thc phn b nhn ca LDP

LDP c hai phng thc phn b nhn: ng xung theo yu cu v ng xung khng theo yu cu. Trong c hai trng hp, nt ng xung u chu trch nhim phn b nhn, nhng phng thc phn b nhn ng xung khng theo yu cu nt ng xung ch phn b nhn khi c kh nng.

- Trong phng thc phn b nhn theo yu cu, b nh tuyn LSR ng xung gi bn tin nh x nhn ti nt ng ln yu cu gi tin gn nhn trn mt giao din ra ti LSR ng xung. Giao din ny c nhn dng v nhn yu cu c mang trong bn tin.

- Vi phng thc phn b nhn khng yu cu, b nh tuyn ng ln la chn nhn v cp pht cho b nh tuyn ng xung.

3.3.1.3. Phng thc duy tr nhn

Sau khi mt b nh tuyn ng ln LSR nhn c pht hnh nhn mi t mt b nh tuyn ng xung, n cn phi thay th cc nhn trong bng nh tuyn thng tin nhn LFIB. B nh tuyn c hai s la chn: Duy tr nhn c (duy tr nhn

tin tin) hoc loi b nhn c thay th bng nhn mi (duy tr nhn bo th).

Nu mt LSR h tr phng thc duy tr nhn tin tin, n c th duy tr lin kt nhn vi cc FEC v s dng khi cn. Vic ny c thc hin mt cch t ng m khng cn n bo hiu LDP hay qu trnh phn b nhn mi.

- u im: Kh nng phn ng nhanh hn khi c s thay i nh tuyn. Phng thc duy tr nhn tin tin tng thch vi phng thc phn b nhn khng theo yu cu v bng c s d liu chuyn tip lun c sn cc nhn cp pht cho b nh tuyn LSR ng xung.

- Nhc im: Tiu tn b nh v khng gian nhn.

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Khi LSR hot ng ch duy tr nhn bo th, n s ch gi nhng gi tr nhn/FEC m n cn ti thi im hin ti, khi c yu cu lin kt nhn t cc b nh tuyn ng xung, cc nhn c cp pht bng cch thay th nhn c bng nhn mi.

+ u im: Khng gian nhn s dng nh hn.

+ Nhc im: Thi gian x l cp pht nhn di, ci thin iu ny b nh tuyn ng xung pht hnh nhn theo chu k hoc s dng bn tin yu cu nhn.

3.3.2. Giao thc phn b nhn da trn nh tuyn rng buc CR - LDP

Mt gii php phn phi nhn c ci thin t LDP nhm h tr k thut lu lng TE c th hin qua giao thc phn phi nhn nh tuyn rng buc CR LDP (Contraint Routing - LDP). Giao thc ny l phn m rng ca LDP cho qu trnh nh tuyn rng buc ca LSP. Cng ging nh LDP, n cng s dng cc phin TCP gia cc LSR ng cp gi cc bn tin phn phi nhn.

Cc chc nng m rng so vi LDP gm c:

- Kh nng thit lp cc ng dn chuyn mch nhn LSP vi iu kin rng buc.

- Phn phi nhn theo tham s lu lng.

- Chim gi trc v phn lp ngun ti nguyn.

Giao thc nh tuyn rng buc phn phi nhn c pht trin v hai l do c bn. Trc ht, MPLS cho php tch cc thng tin s dng chuyn tip nhn t cc thng tin tiu ca gi IP. Th hai l vic chuyn i gia lp chuyn tip tng ng v ng chuyn mch nhn ch c gii hn trong b nh tuyn ti mt u ca ng chuyn mch nhn. Ni cch khc, vic quyt nh gi IP no s nh tuyn ngun nh th no hon ton do b nh tuyn pha ngun tnh ton xc nh tuyn.

i vi nh tuyn rng buc, ta c th xem mt mng nh l mt tp hp cc nt mng v mt tp hp cc kt ni gia cc nt mng . kt ni gia hai nt bt k th cn phi tha mn mt s rng buc v coi cc rng buc ny nh c im ca cc knh. Nhim v ca nh tuyn rng buc l tnh ton xc nh ng kt ni t nt ny ti nt kia sao cho tha mn mt s iu kin rng buc c t ra vi lin kt . Cc iu kin rng buc c th l mt trong nhiu cc tiu ch nh s nt t nht, ng i ngn nht, bng thng rng nht, dung lng ng truyn, thi gian thc,

GVHD: Trang 19

Ngoi cc iu kin rng buc c t ra i vi knh, cn c cc iu kin c t ra vi vic qun tr. Chng hn nh qun tr mun ngn khng cho mt lu lng no i qua mt s knh nht nh trng mng c xc nh bi mt s c im no . Do , thut ton nh tuyn m nh qun tr phi thc hin l tm cc knh xc nh m n cho qua lu lng trn, ng thi tha mn mt s iu kin rng buc khc na.

nh tuyn rng buc cn c th l s kt hp ca c hai iu kin rng buc l qun l v c im knh mt cch ng thi ch khng phi tng iu kin ring r.

im khc bit chnh gia nh tuyn IP truyn thng vi nh tuyn rng buc l: thut ton nh tuyn IP truyn thng ch tm ra mt ng ti u ng vi duy nht mt tiu ch c t ra, trong khi thut ton inh tuyn rng buc va tm ra mt tuyn ng ti u theo mt tiu ch no ng thi phi tha mn mt s iu kin rng buc nht nh. Chnh v iu ny m thut ton nh tuyn rng buc trong mng MPLS c th p ng c yu cu trong khi cc mng s dng thut ton tm ng khc khng th c c, k c giao thc nh tuyn IP.

lm c iu ny, c rt nhiu nguyn nhn. Trong , nguyn nhn chnh l do nh tuyn rng buc yu cu ng i phi c tnh ton v xc nh t pha ngun. Cc ngun khc nhau c cc rng buc khc nhau i vi mt tuyn ng trn cng mt ch. Cc iu kin rng buc ng vi b nh tuyn ca mt ngun c th ch c bit n bi b nh tuyn m thi, khng mt b nh tuyn no khc trn mng c bit v iu kin ny. Ngc li, trong b nh tuyn IP th ng i c xc nh v tnh ton bi tt c cc b nh tuyn phn tn ton mng.

Mt nguyn nhn khc l kh nng nh tuyn ngun v cc ngun khc nhau c th tnh ton xc nh cc ng khc nhau n cng mt ch. V vy, ch da vo thng tin v ch l khng c th xc nh ng truyn gi tin.

Mt nguyn nhn na l i vi phng php nh tuyn rng buc th vic tnh ton xc nh ng i phi tnh n cc thng tin v c im tng ng ca tng knh trong mng. i vi cc phng php IP n gin khng h tr kh nng ny. Giao thc nh tuyn truyn thng da vo trng thi knh ch truyn duy nht cc thng tin bn, ri ca tng knh v di ca tng knh, cc giao thc nh tuyn vector khong cch ch truyn o cc thng tin a ch nt tip theo v khong cch.

3.4. Phn b nhn da trn giao thc dnh trc ti nguyn RSVP

Giao thc dnh trc ti nguyn RSVP l giao thc bo hiu h tr cht lng dch v trong IP cho cc lung lu lng ng dng. Cc thit b u cui s dng giao thc RSVP yu cu cc cht lng dch v t mng cho cc lung lu lng thc

GVHD: Trang 20

t. Cc b nh tuyn s dng RSVP to ra cc yu cu cht lng dch v cho ton b cc b nh tuyn dc theo tuyn ng gi tin truyn qua mng.

Hnh 3.2. S dng RSVP phn b nhn

thit lp mt ng i t ngun ti ch, pha pht s dng bn tin PATH thit lp trng thi ng i qua cc nt trung gian da vo nh tuyn ti cc nt ny. Sau , pha nhn s s dng bn tin RESV vi cc tham s v lu lng v cht lng dch v, i theo chiu ngc li vi chiu gi chim d ti nguyn ti mi nt trn ng i . Bn tin hng ngc RESV ca giao thc RSVP s mang nhn c cp pht bi b nh tuyn.

Mi nt trn ng i nhn c bn tin RESV s kim tra ti nguyn hin c v so snh vi ti nguyn yu cu. Nu ti nguyn hin c khng p ng yu cu th nt ny s gi bn tin bo li n c pha gi v pha nhn gii phng trng thi ng i v ti nguyn chim d. Nu tt c cc nt trung gian trn ng i c ti nguyn h tr th ng i s c thit lp. V giao thc RSVP da trn giao thc IP khng tin cy gi bn tin bo hiu nn khng m bo qu trnh chim gi ti nguyn din ra t u n cui. Do vy khi pha gi nhn c bn tin RESV, n s gi thm mt bn tin RESVCONF khng nh kt qu i vi pha nhn.

RSVP c th dng thit lp mt tuyn v dnh trc cc nhn MPLS ti cc nt gia cc nhm truyn thng. Bn tin RSVP c truyn li theo cng tuyn m bn tin PATH quan h ca n a ra. Chc nng ca lung bn tin ny hon thnh mt nh tuyn MPLS gia cc ngi dng. Cc nhn ny c phn vo bng nhn c to ra mi nt.

3.5. u im nhc im ca MPLS trong mng NGN

3.5.1. u im

- Kh nng tch hp cc chc nng nh tuyn, nh a ch, iu khin v.v... trong MPLS trnh c s phc tp trong NHRP, MPoA, IpoA

- Kh nng m rng n gin.

GVHD: Trang 21

- Tng cht lng mng, c th trin khai cc chc nng nh tuyn m cc cng ngh trc khng th thc hin c nh nh tuyn hin (explicit routing), iu khin lp v.v..

- Tch hp gia IP v ATM cho php tn dng ton b cc thit b hin ti trn mng.

- Tch bit n v iu khin vi n v chuyn mch cho php MPLS h tr ng thi MPLS v B-ISDN. Vic b sung cc chc nng mi sau khi trin khai mng MPLS ch cn thay i phn mm iu khin.

3.5.2. Nhc im

- H tr ng thi nhiu giao thc s gp phi nhng vn phc tp trong kt ni.

- Kh h tr QoS xuyn sut.

- Hp nht VC cn phi c nghin cu su hn gii quyt vn chn gi tin khi trng nhn (interleave).

3.6. ng dng MPLS trong mng NGN

MPLS cho php cc nh cung cp dch v tch bit vic kim sot lu thng m yu cu ca ng dng. MPLS cn c kh nng cho php ng dng t ng yu cu ti chng cn s dng trn h tng mng. Tuy nhin, cht lng mng ch da vo mt mnh IP th khng , do vy tnh thng minh cng thm l cn thit cht lng, bo mt, k ton v thanh ton cho dch v mi. Vic kim sot tt hn cng l iu cn thit cho php nh cung cp dch v c th kim sot lu thng trn mng.

S chuyn bin kin trc mng ny, khng gii hn cc nh cung cp dch v cng cng m ngay c cc doanh nghip/t chc ln cng chuyn ha. V d nh B Ti chnh. Mng ca B Ti chnh l h thng mng kh phc tp, phc v cho nhiu phn h, ban ngnh trong B, cng ging nh mng ca cc nh cung cp dch v vin thng VNPT, EVN Telecom, Viettel... Chnh v vy, thit k cho mng ca B Ti chnh phi l ti u, n nh, kim sot tp trung, an ninh, an ton v bo mt, ng thi phi c tng thch cao gia cc thit b mi v thit b sn c. V B Ti chnh i n quyt nh ng dng mng NGN c thit k vi cng ngh MPLS hin i.

Nhu cu ca B Ti chnh trong vic xy dng mng tch hp a dch v c th hin tm tt nh sau: Xy dng tng th mt mng tch hp a dch v, kt ni ti 64 tnh thnh v tch hp vi h thng mng hin ti. Kt ni vt l ch yu da trn cc lung leased-line v MPLS VPN, ngoi ra cn c cc ng truyn dn cp quang

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vi bng thng FE/GE cho mt s mng LAN v campus ti HCM/HNI. T chc mng s c chia thnh 3 trung tm min. Trung tm d liu (Data Center) v vn hnh mng NOC s tp trung ti H Ni v TP. HCM. Thit k cng phi cp n gii php tch hp v chuyn i mng hin ti thnh mt mng thng nht... Hin nay, B Ti chnh vn ang trin khai cng ngh NGN ti cc tnh thnh trong c nc v bc u thu c nhng li ch ln.

Va qua, Pacific Airlines lm mt cuc cch mng trong hot ng kinh doanh ca mnh, t s dng v giy n chuyn hon ton sang TMT tt c cc khu: t ch, mua v, in v, thanh ton hon ton qua mng Internet. Bc ngot ny mang li cho Pacific Airlines mt ngun li ln. Hin nay, Pacific Airlines ang s hu mt h thng bn v hin i nht Vit Nam vi phn mm ca Navitaire v h tng mng ca Juniper Networks. Vic ng dng cng ngh MPLS hin i vi thit b tng la SSG ca Juniper mang li cho Parcific Airlines nhng hiu qu nh sn sng cao trn ton h thng vi vic d phng trn thit b, ng truyn. iu ny nhm m bo h thng th tn, cc giao dch in t cng nh cc ng dng khc lun trong tnh trng sn sng, gim thiu cc s c ngt mng nn p ng ti a nhu cu kinh doanh cho Pacific Airlines; Kt ni an ton cho cc chi nhnh c nh s dng mi trng Internet, gim chi ph i vi ngi dng t xa hay cc chi nhnh t ti i Bc, c Chu giao din ngi dng lun to cm gic thn thin, gip nhn vin ng nhp mng mt cch d dng m khng cn ci t my tnh phc tp, hay mt cng o to...

Cng ngh NGN to ra c hi gim thiu chi ph trong sn xut kinh doanh v tng kh nng cnh tranh cao trong mi trng kinh doanh hin nay. Vi vic s dng cc thit b nh thch hp hn v tn t nng lng hn, tit kim nhn lc, tit kim chi ph hng ngy, c bit l nhng tin ch v qun l cht lng tt v rt hiu qu khi cho kt ni phn tn nhng li tp trung vo mt mi, NGN/ MPLS tr thnh s la chn ti u cho cc t chc v doanh nghip

i vi Vit nam, vic trin khai MPLS hin ang c xc tin xy dng trong mng truyn ti ca tng cng ty BCVT Vit nam. Vi d n VoIP hin ang trin khai, VNPT thit lp mng trc MPLS vi 3 LSR li. Cc LSR bin s c tip tc u t v m rng ti cc a im c nhu cu ln nh Hi Phng, Qung Ninh pha Bc, Nng, Khnh Ho... min Trung, Bnh Dng, ng Nai, B Ra - Vng Tu... min Nam.

Trong cu hnh ny, cng ngh MPLS c trin khai khng ch trong lp li (MPLS core) m cn trong lp bin (MPLS edge). Cc thit b MPLS lp bin ng vai tr nh nhng LSR li vo, li ra. Cc mng Internet quc gia, mng truyn s

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liu, mng DCN (qun l) u c kt ni vi cc LSR bin. Vic chuyn tip cc thng tin ny c thc hin qua mng MPLS v n cc LSR bin li ra.

Cu hnh ny ha hn kh nng iu khin nh tuyn, chuyn mch n gin da trn cc nhn ca MPLS, kh nng cung cp cht lng dch v xuyn sut bo m. Tuy nhin cn rt nhiu vn k thut phi quan tm phn tch khi xy dng cu hnh chi tit bo m kh nng tng thch gia cc thit b v hot ng ca mng. Mt trong nhng vn quan trng cn quan tm l cn xc nh nguyn tc t chc ca nhng nt LSR trong mng, cn phn nh r rng giao din v chc nng ca tng thnh phn thit b trong mng li, mng bin. Trong qu trnh xy dng cu hnh ny nn tham kho m hnh do MSF (Multiservice Switch Forum), mt t chc chuyn v cc thit b chuyn mch trong mng th h sau xut.

Cc dch v c th cung cp trong mng MPLS xut bao gm:

- Ti tin cho cc mng s liu, Internet v thoi quc gia. Lu lng thoi c chuyn dn sang mng trc MPLS quc gia. Mng ny s thay th dn mng trc TDM quc gia ang hot ng.

- Cung cp dch v truy nhp Internet tc cao ti mt s a phng trng im trn ton quc. Bc u hnh thnh mng trc quc gia trn c s cng ngh gi.

- Cung cp dch v truyn s liu tc cao cho cc doanh nghip nh Ngn hng, cc hng thng tn bo ch.

- Cung cp dch v mng ring o VPN cho cc cng ty xuyn quc gia v cc doanh nghip ln. y ang c coi nh dch v quan trng nht tc ng n vic thay i c cu kinh doanh v tng kh nng cnh tranh ca cc nh khai thc.

- Cung cp dch v Video.

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KT LUN

S xut hin ca cng ngh chuyn mch nhn a giao thc gip chng ta c c s la chn tt cho cu trc mng thng tin tng lai. Phng php ny tch hp mt cch hu hiu nng lc iu khin lu lng ca thit b chuyn mch vi tnh linh hot ca b nh tuyn.

Nhn chung, MPLS c rt nhiu u im nh n gin, tch hp nh tuyn v chuyn mch, h tr cht lng dch v chp nhn c. MPLS h tr mm do v linh hot cho tt c cc dch v trn mt mng. Bn cnh tin cy, cng ngh MPLS cng khin cho vic qun l mng c d dng hn. Do MPLS qun l vic chuyn tin theo cc lung thng tin, cc gi tin thuc mt lp chuyn tip tng ng c th c xc nh bi mt gi tr nhn. Do vy, trong min MPLS c th da trn nhn phn loi gi tin.

Tuy nhin, MPLS cng c mt s nhc im nh gi thnh cao hn IP truyn thng, chun ha ang trong giai on tip tc pht trin. Do MPLS l cng ngh chuyn mch hng kt ni, kh nng nh hng bi li ng truyn thng thng cao hn cc cng ngh khc.

Tm li, MPLS l mt cng ngh chuyn mch c nhiu trin vng v n s ha hn l mt phng n l tng cho mng ng trc trong tng lai.

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TI LIU THAM KHO

[1] TS. Hong Minh ThS. Hong Trng Minh (2009), C s k thut chuyn mch, Nh xut bn thng tin v truyn thng H Ni.

[2] TS Nguyn Qu Minh Hin, Mng vin thng th h sau, Vin khoa hc k thut bu in.

[3] Cornelis Hoogendoom (2002), Next Generation Networks and VoIP

[4] http://www.thuviendientu.org

[5] http://www.tailieu.vn

[6] http://www.thuvienonline.com.vn

[7] http://www.kilobook.com

[8] http://www.webluanvan.vn

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2.1. S ra i ca cng ngh MPLS2.2. c tnh c bn ca MPLS2.3. Cc thnh phn c bn ca MPLS