B CC, CU TRC BI LM PHN I: TNG QUAN MPLS CHNG: Chuyn mch nhn a giao thc MPLS1. Khi nim c bn v MPLS1.1 Li ch ca MPLS1.2 Mt s ng dng ca MPLS2. Cc thnh phn trong MPLS2.1 Nhn (Label)2.2 Ngn xp nhn2.3 Lp chuyn tip tng ng FEC2.4 Dng chuyn mch nhn LSP2.5 C s d liu nhn LIB2.6 Topo mng MPLS3. Giao thc phn phi nhn LDP3.1 Qu trnh khm ph lng ging LSR3.2 Cc kiu phn phi nhn4. Cu trc MPLS4.1 Mt phng iu khin4.2 Mt phng d liu4.3 Cc thnh phn bn trong mt phng diu khin v mt phng d liu5. Cc giao thc nh tuyn trong MPLS5.1 Giao thc inh tuyn OSPF5.2 Giao thc inh tuyn EIGRP5.3 Giao thc nh tuyn BGP6. Phng thc hot ng ca MPLSPHN II: TRIN KHAI CI T MPLS

I. Tng quan MPLS

1.1 nh nghaChuyn mch nhn a giao thc (MPLS - Multiprotocol Label Switching) l mt cng ngh lai kt hp nhng c im tt nht gia nh tuyn lp 3 (layer 3 routing) v chuyn mch lp 2 (layer 2 switching) cho php chuyn ti cc gi rt nhanh trong mng li (core) v nh tuyn tt cc mng bin (edge) bng cch da vo nhn (label).1.2. Li ch ca MPLS- Lm vic vi hu ht cc cng ngh lin kt d liu.- Tng thch vi hu ht cc giao thc nh tuyn v cc cng ngh khc lin quan n Internet.- Hot ng c lp vi cc giao thc nh tuyn (routing protocol).- Tm ng i linh hot da vo nhn(label) cho trc.- H tr vic cu hnh qun tr v bo tr h thng (OAM).- C th hot ng trong mt mng phn cp.- C tnh tng thch cao.

1.3. c im mng MPLS- Khng c MPLS API, cng khng c thnh phn giao thc pha host.- MPLS ch nm trn cc router.- MPLS l mt giao thc c lp nn c th hot ng vi cc giao thc mng khc IP nh IPX, ATM, Frame-Relay, PPP hoc trc tip vi tng Data Link.- nh tuyn trong MPLS c dng to cc lung bng thng c nh tng t nh knh o ca ATM hay Frame Relay.- MPLS n gin ho qu trnh nh tuyn, ng thi tng cng tnh linh ng vi cc tng trung gian.Mt s khi nim thng gp- FEC (Forwarding Equivalence Class) l mt nhm cc gi tin lp mng c dn nhn ging nhau v gi i ng nht theo mt ng i xc nh.- LSR (Label Switching Router) l b nh tuyn c h tr MPLS, bao gm cc giao thc iu khin MPLS, cc giao thc nh tuyn lp mng v cch thc x l nhn MPLS.- LER( Label Edge Router) l cc LSR bin mng MPLS trong MPLS domain, gm c LER vo (Ingress LER) v LER ra (Egress LER).- LSP (Label Switching Path) l ng i xut pht t mt LSR v kt thc ti mt LSR khc. Tt c cc gi tin c cng gi tr nhn s i trn cng mt LSP.- MPLS domain l tp cc nt mng MPLS.

3. Kin trc MPLS* Label : Nhn c s dng trong tin trnh gi gi tin sau khi thit lp ng i. MPLS tp trung vo qu trnh hon i nhn (Label Swapping).Mt trong nhng th mnh ca kin trc MPLS l t nh ngha cc chng nhn(label stack). Cng thc dn nhn gi tin l: Network Layer Packet + MPLS Label StackLabel Spaces : chia lm 2 loiPer-Platform Label Space: cc interface dng chung gi tr nhn.Per-Interface Label Space: mi interface mang gi tr nhn ring.Hot ng ca LSR :- tng chnh ca MPLS l s dng nhn quyt nh chn k tip, nn router lm vic t hn v hot ng gn ging nh switch. V cc nhn th hin cc tuyn ng trong mng nn ta c th iu khin chnh xc qu trnh x l lu lng bng cch dng cc chnh sch gn nhn.+ chng router u tin, router chuyn gi tin da vo a ch ch, xc nh nhn thch hp ty vo FEC gn nhn cho gi & chuyn gi i tip.+ chng k tip, LSR dng gi tr nhn xc nh nt tip theo cn chuyn gi, gn nhn mi ri chuyn gi i tip.Label Switch Path - LSP : LSP xc nh ng i gi tin MPLS, chia lm 2 loi: Hop by hop signaled LSP - xc nh ng i kh thi nht (best-effort path) v Explicit route signaled LSP(ER-LSP) - xc nh cc tuyn ng i bt ngun t nt gc.ER-LSP c cc u im sau: kh nng nh tuyn linh hot, xc nh nhiu ng i n ch, qun l lu lng linh hot, vic tm ng da trn quan h rng buc nh mng ATM.Mt s ng dng-Cc dch v internet c th chia lm 3 nhm chnh:voice, data, video vi cc yu cu khc nhau. Nh voice yu cu tr thp, cho php tht thot d liu tng hiu qu. Video cho php mt mt d liu mc chp nhn c, mang tnh real time. Data yu cu bo mt, chnh xc cao...Vic trin khai cng ngh MPLS lm tng hiu qu khai thc cc ti nguyn mng sao cho hu hiu nht.Hin c mt s ng dng MPLS ang c trin khai l:- MPLS Traffic Engineering- MPLS VPN- MPLS QoS- MPLS Unicast/Multicast IP RoutingNhn xtGii php chuyn mch nhn a giao thc l mt k thut mng mi vi mc tiu kt hp tnh mm do ca cng ngh IP v ATM.

MPLS bao gm 3 thnh phn chnh:- Giao thc nh tuyn IP nh OSPF, BGP ti bin mng v li mng tm kim cc b nh tuyn MPLS.- Chuyn mch gi tin da trn a ch IP ti bin mng.- Gn nhn v phn b nhn trong li mng gi gi nhanh v hiu qu nht.Phng php nh tuyn trong MPLS h tr 2 dng hop-by-hop(nh tuyn tng bc) v explicit(nh tuyn ngun). Phng php nh tuyn ngun c tnh ng ln hn trn c s yu cu QoS v cc chnh sch khc.

Qu trnh phn phi nhn l c lp vi qu trnh truyn tin v thng qua giao thc phn phi nhn. Qu trnh gn nhn v phn phi nhn ph thuc rt nhiu vo topo mng, lu lng iu khin v lu lng s liu.i vi nh qun tr mng s quan tm n MPLS kha cnh qun l chnh sch quyt nh nhn no dng u, ch khng phi l cc nhn thc t c phn phi nh th no.

Phn tch cc bng RIB, LIB, FIB, LFIB1.RIB (Router Information Base)

RIB gi thng tin nh tuyn ng nhn c thng qua cc giao thc nh tuyn. Mt RIB thng bao gm nhiu tuyn cho mt a ch ch. V d mt RIB c th nhn cc tuyn ging nhau t cc giao thc nh tuyn khc nhau hoc nhiu tuyn t mt giao thc nh tuyn. i vi mt a ch IP ch, RIB cung cp mt hoc nhiu con ng i.

FIB l mt tp con ca RIB, n gi li tuyn tt nht dng chuyn tip.RIB ch chn nhng tuyn tt nht c th dng vo trong FIB cho mi prefix. Tuy nhin khng phi v th m cc c tnh ca FIB suy gim.

Hnh: Cu trc ca RIB

2.LIB(Label Information Base)Cc LSR lu tr cc nhn v cc thng tin lin quan bn trong mt cu trc d liu gi l LIB. V c bn LIB lu tr tt c cc nhn v cc thng tin lin kt c th c s dng chuyn tip cc gi. Tuy nhin mi LSR phi chn nhn tt nht v giao tip ra thc s s dng chuyn vo FIB v LFIB.V d bng LIB.

3.FIB(Forwarding Information Base)

Hnh: Bng FIB

Cc bng FIB (Forwarding Information Base) cha cc thng tin chuyn tip IP t Router v chun b qun l d liu ny tra cu phn cng v chuyn tip. Nhngthng tin trong bng FIB c th c to theo kiu ng hay tnh, v kt hp t cc loi mc khc nhau nh: a ch Giao thc quyt nh (ARP), mc tnh, mc t xanng ng, vv. Cc thc th FIB c th bit c t cc giao thc nh tuyn IP, cc tuyn ng tnh, nh ngha tnh v ARP entries. Bng FIB c thi gian lo ha m bn c th cu hnh. Ngoi ra bn c th thm, chnh sa hoc loi b cc mc tnh theo nhu cu.

C s thng tin chuyn tip (FIB) cng tng t nh mt bng nh tuyn hoc thng tin c bn. N t ng gi mt bn sao ca thng tin phn nh chuyn tip chatrong bng nh tuyn IP. Khi nh tuyn hoc topo thay i xy ra trong mng li, cc bng ch IP nh tuyn c cp nht, v nhng thay i c phn nh trong FIB. FIB duy tr thng tin a ch hop tip theo da trn thng tin trong bng nh tuyn IP.

4.LFIB (Label Forwarding Information Base)

LFIB trong mt node MPLS bao gm mt chui cc thc th. Mi mt thc th bao gm mt nhn ng vo v mt hoc nhiu thc th con (c minh ha trong hnh bn di).LFIB l bng lit k cc gi tr cha trong nhn ng vo.

Hnh: Cu trc bng LFIB

Mi thc th con bao gm mt nhn ng ra, giao tip ng ra v a ch hop k tip. Cc thc th con trong mt thc th ring l c th c cc nhn ng ra ging hoc khc nhau.V d bng LFIB.