K THUT LU LNG TRONG MPLS

BO CO CHUYN :

TM HIU V MPLS TRAFFIC ENGINEERING

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TM HIU V MPLS TRAFFIC ENGINEERING

A.L THUYT V MPLS-TE.II. MPLS-TE L G? LI CH CA VIC S DNG MPLS-TE:Gii thiu v MPLS TE:Multiple Protocol Lable Switching. Chuyn mch nhn a giao thc (MPLS - Multiprotocol Label Switching) l mt cng ngh 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).

Li ch ca MPLSTE: 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.

c im mng MPLS TE: 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.

Lch s hnh thnh: Vo thp nin 90, cc ISP pht trin mng ca h theo m hnh chng lp (overlay) bng cch a ra giao thc IP over ATM ATM l cng ngh connection-oriented, thit lp cc knh o (Virtual Circuit), tuyn o (Virtual Path) to thnh mt mng logic nm trn mng vt l gip nh tuyn, phn b ti ng u trn ton mng. nh tuyn trong mng IP c iu chnh bi nhu cu c c lu lng truy cp trn mng ln nht c th. l l do ti sao nh tuyn IP c da trn nguyn tc nh tuyn chi ph c bn thp nht. Tt c cc nh tuyn vi giao thc IP c chi ph lin quan n cc lin kt trong mng. S tch ly ca cc chi ph tt c cc lin kt ca mt ng i c s dng tnh ton ng i chi ph nh nht chuyn tip lu lng truy cp thng qua mng. Chi ph l mt metric duy nht c gn cho mt lin kt IP v ATM l hai cng ngh hon ton khc nhau, c thit k cho nhng mi trng mng khc nhau, khc nhau v giao thc, cch nh a ch, nh tuyn, bo hiu, phn b ti nguyn... Khi cc ISP cng m rng mng theo hng IP over ATM, h cng nhn r nhc im ca m hnh ny, l s phc tp ca mng li do phi duy tr hot ng ca hai h thng thit b.S bng n ca mng Internet dn ti xu hng hi t cc mng vin thng khc nh mng thoi, truyn hnh da trn Internet, giao thc IP tr thnh giao thc ch o trong lnh vc mng. Xu hng ca cc ISP l thit k v s dng cc router chuyn dng, dung lng chuyn ti ln, h tr cc gii php tch hp, chuyn mch a lp cho mng trc Internet. Nhu cu cp thit trong bi cnh ny l phi ra i mt cng ngh lai c kh nng kt hp nhng c im tt ca chuyn mch knh ATM v chuyn mch gi IP. Cng ngh MPLS ra i trong bi cnh ny p ng c nhu cu ca th trng ng theo tiu ch pht trin ca Internet mang li nhng li ch thit thc, nh du mt bc pht trin mi ca mng Internet trc xu th tch hp cng ngh thng tin v vin thng (ICT - Information Communication Technology) trong thi k mi cc ISP l thit k v s dng cc router chuyn dng, dung lng chuyn ti ln, h tr cc gii php tch hp, chuyn mch a lp cho mng trc Internet. Nhu cu cp thit trong bi cnh ny l phi ra i mt cng ngh lai c kh nng kt hp nhng c im tt ca chuyn mch knh ATM v chuyn mch gi IP. Cng ngh MPLS ra i trong.

III. CC THUC TNH CA MT LIN KT TRONG MPLS-TE:Mi lin kt trong mng MLS c trin khai k thut lu lng c nhng c tnh c lan truyn ra cc router, cc router ny khi tnh ton mt tuyn LSP xem xt liu c th s dng c mt lin kt no cho TE-LSP. Cac lin kt o co nhng cu hinh c tinh nh sau:

1. Bng thng c sn (available bandwidth):Mt thuc tnh quan trng ca MPLS TE l kh nng dnh ring bng thng qua mng. Cu hnh mt lng bng thng dnh ring trn mt lin kt bng cch s dng lnh sau:Code:Router(config-if)#ip rsvp bandwidth [[per-flow-bandwidth]]

Lnh ny c th ly hai tham s. Tham s u l tng lng bng thng dnh ring trn giao tip, tnh bng Kbps. Tham s th hai l lng bng thng ti a c th dnh ring trong lung lu lng trn mt giao tip.Nu khng cu hnh lnh th bng thng dnh ring ngm nh qung co cho giao tip bng 0.

Nu khng ch nh gi tr cho total-reservable-bandwidth trong lnh ip rsvp bandwidth th gi tr mc nh l 75% ca bng thng lin kt (link bandwidth). Bng thng lin kt c xc nh bi loi giao tip hoc lnh v bng thng trn giao tip.

T l trn lung lu lng (per-flow) ti a c ngm nh l bng tham s total-reservable-bandwidth, nhng khng nht thit phi lun lun nh th.Khi cc ng hm MPLS TE dnh ring bng thng lin kt, lng bng thng c nh phn (allocated bandwidth) thay i nhng bng thng c sn ti a (maximum available bandwidth) khng thay i.

2. u tin ng hm (Tunnel Priority):MPLS TE cung cp c ch u tin cho mt s ng hm lm vic trc nhng ng hm khc. Mi ng hm c mt u tin, cc ng hm t quan trng hn b y ra khi ng i v c tnh ton li ng i, v ti nguyn ca n nhng li cho ng hm quan trng hn._ Cc mc u tin (Priority Level): Mt ng hm c th c thit lp u tin vi gi tr trong khong t 0 n 7. Gi tr u tin cng ln th s quan trng ca ng hm cng thp ! V d, ng hm c u tin 3 th quan trng hn ng hm u tin 5. u tin 0 l quan trng nht.

Nhng c s ca s u tin (Preemption Basics):

Nhng ng hm quan trng hn c quyn y nhng ng hm khc ra khi ng i khi mun dnh ring bng thng. iu ny c gi l s chim trc ng hm (tunnel preemption). u tin thit lp v u tin lu gi (Setup and Holding Priority):Mi ng hm c hai u tin u tin thit lp (Setup priority) v u tin lu gi (Hold priority). Chng c xem nh mt u tin nhng cn phi tm hiu c ch lm vic v ti sao c hai u tin thay v mt.

u tin thit lp c th khc vi u tin lu gi cho mt vi ng dng thc t. V d, mt ng hm c u tin lu gi bng 0, v u tin thit lp l 7. ng hm ny c th b bt k mt ng hm khc y ra khi ng i ca n chim ti nguyn v ng hm c u tin thit lp thp nht (7). Nhng ngay lc n c thit lp th khng ng hm no khc c th chim trc ng i ca n do c u tin lu gi cao nht (0).

Ch , cng mt ng hm th u tin thit lp khng c tt hn u tin lu gi. V nu hai ng hm (gi s l Tunnel1 v Tunnel2) ang tranh chp cng ti nguyn, v c hai u c u tin thit lp bng 1 v u tin lu gi bng 7, iu g xy ra?

1) Tunnel1 n u tin v gi bng thng vi u tin lu gi bng 7.2) Tunnel2 n th hai v dng u tin thit lp ca n (1) y Tunnel1 ra chim ng lin kt (link). Sau Tunnel2 gi ng lin kt vi u tin lu gi bng 7.3) Tunnel1 n v s dng u tin thit lp (1) y Tunnel2 i v chim ng lin kt. Tunnel2 gi lin kt vi u tin lu gi bng 7.4) Tunnel2 n v dng u tin thit lp ca n (1) y Tunnel1 ra chim ng lin kt . Sau Tunnel2 gi ng lin kt vi u tin lu gi bng 7.5) Tr li bc 3) v lp li.

Cc phin bn Cisco IOS u khng cho php cu hnh u tin thit lp thp hn u tin lu gi trn cng mt ng hm nn trong thc t khng xy ra hin tng trn.

Tuy nhin, trong thc t him khi u tin thit lp v u tin lu gi khc nhau.

Nu khng ch nh mt u tin lu gi th ngm nh bng vi gi tr ca u tin thit lp.

u tin ngm nh l 7 (cho c hai u tin thit lp v lu gi)

3. Cc c thuc tnh (Attribute Flags):Mt c tnh khc ca MPLS TE l cc c thuc tnh. Mt c thuc tnh l mt nh bipmap 32-bit trn mt kt ni c th cha 32 thuc tnh ring bit trn mt kt ni. Lnh trn kt ni nh sau:Code:Router(config-if)#mpls traffic-eng attribute-flags attributes (0x0-0xFFFFFFFF)Cc thuc tnh (attributes) c th t 0x0 n 0xFFFFFFFF. N i din mt nh bitmap ca 32 thuc tnh (bit), vi gi tr ca mt thuc tnh l 0 hoc 1. Ngm nh l 0x0, hay tt c 32 thuc tnh trong nh bitmap l 0.Bn c th t quyt nh cho nhng bit ny. V d, quyt nh gi tr c thuc tnh l 0x2 ngha l Kt ni ny c nh tuyn qua mt ng v tinh v do khng ph hp i qua nhng ng c tr thp (low-delay). Trong trng hp ny bt k kt ni no qua v tinh s c cu hnh nh sau:

Code:Router(config-if)#mpls traffic-eng attribute-flags 0x2

4. Trng lng qun tr (Administrative Weight):Chi ph trn kt ni chia lm hai loi: chi ph iu khin lu lng (TE cost) v chi ph ca giao thc cng ni (IGP cost). Cho php tnh ton ng i TE thit lp chi ph kt ni khc vi ng i ngn nht u tin ca giao thc IGP (IGP SPF).Chi ph TE ngm nh trn mt kt ni bng vi chi ph IGP. Thay i chi ph TE khc vi chi ph IGP bng cch s dng lnh sau:router(config-if)#mpls traffic-eng administrative-weight (0-4294967295)administrative-weight l lnh dng thit lp trng lng qun tr hay metric trn mt giao tip. Lnh ny s dng cho hai trng hp:

-TH 1:ghi metric c IGP qung co nhng ch trn nhng thng tin qung co ca TE.-TH2:l metric nhy cm (delay-sensitive metric) vi tr trn mt c s ng hm (per-tunnel basis)

Trng hp 1 c c OSPF v IS-IS quan tm, khi mt kt ni c qung co vo IGP n km theo mt metric ca kt ni (link metric). Metric ca kt ni trong IS-IS mc nh l 10, v c th c cu hnh li bng lnh per-interface commamd isis metric. Metric kt nt ngm nh ca OSPF bng bng thng trn kt ni chia 108, v c th c cu hnh bng lnh per-interface commamd ip ospf cost.

Nu trng lng qun tr iu khin lu lng mpls (mpls traffic-eng administrative-weight) cha c cu hnh trn mt giao tip, chi ph c qung co trn thng bo iu khin lu lng bng vi chi ph IGP cho kt ni . Tuy nhin c mt trng hp bn mun thay i gi tr chi ph c qung co trn kt ni cho TE. iu hy hu dng trong cc mng c c hai loi chuyn tip lu lng : IP v MPLS TE.Vic cu hnh trng lng qun tr trn lin kt s to nn s khc bit v tr nhng khng thay i bng thng.

5. Nhm lin kt chia s nguy c:Ch nh nhng lin kt c dng chung ng truynvt l (v d cp quang). Nu ng truyn ny b t th s nhng lit kt ny b nh hng cng thi im. SRLG c s dng cho trng hp dphng FRR.

6. Bng thng sub-pool dnh ring ln nht: l bng thng dnh ring cho nhng dch v phn bit (DiffServ-aware). N l mt phanh mnh ca bng thng dng chung.

III. CC THUC TNH CA TRUNG K(TUNNEL) TRONG MPLS-TE:Trc khi thit lp 1 tunnel mi, ta phi t ra cc thuc tnh cho LSP mun thit lp v n ch c thit lp khi cc lin kt trong mng p ng c cc thuc tnh ny. Cc thuc tnh ca 1 LSP bao gm:1. a ch ch ca tunnel:L a ch m LSP s c kt ni n, hay ni ng hn l a ch RouterID ca router tail end.2. Bng thng mong mun:Gi tr bng thng cho kt ni, ch nhng lin kt no trn mng c bng thng dnh ring cc i ln hn hoc bng gi tr bng thng mong mun ny khi LSP mi c th c thit lp qua lin kt .3. C thuc tnh ca LSP (Affinity):Hay cn gi l mu ca LSP, n tng ng vi attribute flag trn lin kt.Gm 2 phn Affinity bit v mask. Mi phn l mt gi tr 32 bit.C thuc tnh lm g khi thit lp 1 tunnel? Khi cu hnh thit lp 1 tunnel, ti router head end ta phi cu hnh thng s Affinity bit v mask. Vy lm sao bit lin kt no tha mn yu cu ny? u tin gi tr mask c AND vi c thuc tnh Attribute Flag ca lin kt, kt qu em so snh vi Affinity Flag ca tunnel, nu l ging nhau th ta ni lin kt tha mn yu cu v mu ca tunnel v LSP v ngc li lin kt khng tha mn yu cu ca LSP.

4. Ty chn thit lp ng i:C 2 phng php thit lp ng i cho 1 LSP: tnh (explicit) hay ng (dynamic) Thit lp ng tnh:Cu lnh:Router(config-if)#Tunnel mpls traffic-eng path-option {preference} explicit name {name}.preference l 1 s c th ly t 1 n 1000, nu 1 tunnel c nhiu s preference u tin s thit lp tunnel c preference nh nht, nu yu cu ny thit lp khng thnh cng s chuyn qua thit lp tunnel c s preference cao hn.Tip theo thc hin kch hot tuyn tnh bng lnh:Router(config)#ip explicit-path name {name} enableRouter(cfg-ip-expl-path)#next-address x.x.x.xRouter(cfg-ip-expl-path)#next-address x.x.x.x y x.x.x.x c th l a ch routerID ca LSR hoc a ch IP ca lin kt. Thit lp ng ng:Ch cn cu hnh theo cu lnh:Router(config-if)#Tunnel mpls traffic-eng path-option {preference} dynamicKhi LSR s t ng tnh ton v a ra con ng ti u nht.5. u tin:1 LSP c 2 u tin l u tin ci t (gi tr t 0-7) v u tin nm gi (0-7).Mi tunnel c 1 quan trng khc nhau v thng s u tin cho php nhng tunnel c thng s ny nh hn c th ln chim cc tunnel c gi tr ln hn. Cc tunnel c thit lp sau s so snh u tin thit lp ca mnh vi u tin nm gi ca tunnel trc.

IV. GIAO THC PHN PH THNG TIN TRONG MPLS-TE:C 2 loi giao thc c m rng phn phi thng tin trng thi lin kt gia cc router trong mng MPLS-TE: OSPF m rng v IS-IS m rng. y ch cp n giao thc OSPF m rng v mc ch ca bi bo co.OSPF m rng cho TE mang thm thng tin thuc tnh ca lin kt c cu hnh trn mt router. Cc thng tin c cung cp bi cc phn m rng c th c s dng xy dng mt c s d liu trng thi lin kt m rng ging nh c s d liu trng thi lin kt thng thng, s khc bit l c s d liu trng thi lin kt c m rng (cn c gi l c s d liu k thut lu lng) c thm cc thuc tnh lin kt. Ngi ta c th s dng c s d liu k thut lu lng :1. Gim st cc thuc tnh lin kt.2. nh tuyn ngun da vo cc rng buc.3. Phn m rng ny gm 3 dng bn tin Opaque LSA l loi 9, loi 10 v loi 11, chng khc nhau phm vi lan truyn: Loi 9: Khng lan truyn ra ngoi subnet ca n (link-local). Loi 10: Qung b trong vng ca n. Loi 11: Bn tin loi ny c lan truyn trn min OSPF, hot ng vng chuyn tip nhng khng xut hin vng gc.1. Cu trc ca LSA: LSA Header

Hnh 1: Cu trc chung ca mt Opaque LSA

LSA ID ca 1 opaque LSA c nh ngha gm c 8 bit m t kiu d diu (Opaque type) v 24 bit m t d liu c th (Opaque ID). Trong k thut lu lng LSA c opaque type l 1. Cn li 24 bit l trng i tng, l mt gi tr ty dng duy tr nhiu LSA TE. Gi tr ln nht ca LSAs TE la 16777216.Trong trng Option c thm mt bit mi l O-bit, bit ny ch ra mt router c kh nng truyn v nhn cc Opaque LSA hay khng.*ODCEAN/PMCE*

Bng 1: Trng Option TLV Header:TE LSA l mt bn tin opaque LSA loi 10 c th mang theo mt hoc nhiu Type Length Values (TVL). Mt TLV cho php OSPF mang d liu mt cch linh hot.Cu trc ca TLV:

Hnh 2: Cu trc ca TLV

Nhng TLV ny mang theo d liu MPLS TE c th.TLV cha Router Address TLV v Link TLV: Router Address TLV: Ch ra mt a ch IP n nh ca router qung b m lun cth kt ni nu c bt k mt kt ni no ti n v thng dng mt a ch loopback. Trong cc giao thc khc, Router Address c xem nh mt Router ID. Link TLV: Link TLV m t mt lin kt n, c xc nh bi mt tp cc sub-TLV,cc sub-TLV ny mi thc s mang thng tin thuc tnh ca lin kt. Ch c mt link TLV c mang trong mt LSA.

2. M t sub-TLV:

STTTn Sub-TLV di (Octet)

1Link Type1

2Link ID4

3Local Interface IP Address4

4Remote Interface IP Address4

5Traffic Engineering Metric4

6Maximum Bandwidth4

7Maximum Reservable Bandwidth4

8Unreserved Bandwidth32

9Administrative Group4

Bng 2: OSPF Link TLV Sub-TLV

Link Type: Ch ra lin kt ny l lin kt im-im hay lin kt im-a imLink ID: Xc nh u cui ca lin kt (router ID): vi lin kt im-im th l router ID ca neighbor, vi lin kt a im th l a ch interface ca router c ch nh.Local Interface IP Address: a ch interface tng ng ca lin kt ti router.Remote Interface IP Address: a ch IP ca interface neighbor tng ng trn lin ktUnreserved Bandwidth: Phn bng thng kh dng cn li cha c s dng ti micp trong 8 cp u tin-Gi tr ng ca bng thng c thit lp theo 8 cp u tin t cao ti thp theo th t t 0-7, TE-LSP c u tin cao hn c th chim gi bng thng ca u tin thp hn nhng ngc li th khng.-Gi tr ca n nh hn hoc bng gi tr ca Maximum Reservable Bandwidth , ban u c thit lp bng gi tr ca Maximum Reservable Bandwidth.3. V d:V d bn di cho thy cu hnh cn thit kch hot MPLS TE cho OSPF. Ta cn phi kch hot MPLS trn ton router bng cu lnh mpls traffic-eng tunnels. Khi mi lin kt c cu hnh vi cu lnh trn s c th mang tunnels.

Hnh 2: Cu hnh MPLS TE cho OSPF

Cu lnh mpls traffic-eng router-id interface-name cho php cu hnh mt IP tnh nh MPLS TE router ID (tng t nh OSPF router ID). Ta dng a ch loopback trn router vi mc ch ny. V d bn di cho thy ta c th xc nhn rng OSPF c kch hot chy MPLS TE area 0 v bn tin opaque LSAs loi 10 xut hin trong c s d liu OSPF.

Hnh 3: Xc nhn MPLS TE cho OSPF

v d tip theo, ta s thy c bn tin opaque LSA chi tit. Router qung co l router c OSPF router ID v MPLS TE ID l 10.200.254.2. Lu rng mc d lnh ip rsvp bandwidth c biu th bng n v kilobit/s, bng thng ln nht v bng thng d tr ln nht c biu th bng n v kilobytes/s u ra OSPF. Metric ca lin kt cng chnh l TE metric ca lin kt .

Hnh 4: Chi tit bn tin OSPF Opaque LSA

B. GIAO THC PHN PHI NHN RSVP:Giao thc chim trc ti nguyn (RSVP - Resource Reservation Protocol)RSVP l mt c ch bo hiu dng dnh ring ti nguyn trn mt mng. RSVP khng phi l mt giao thc nh tuyn. Cng vic ca RSVP l bo hiu v duy tr ti nguyn dnh ring qua mt mng.RSVP c ba chc nng c bn: Thit lp v duy tr ng i (Path setup and maintenance). Hy ng i (Path teardown). Bo li (Error signalling).RSVP c s dng trong MPLS nhm thit lp d phng v cht lng dch v trong mng Internet. Router theo di v kim sot vic di chuyn ca gi tin sau khi c s thng nht v ti nguyn s dng gia 2 router. Gi tin c gi u n nh giao thc RSVP gia cc router. Mt cch n gin, giao thc RSVP thc hin vic thit lp v iu khin qu trnh chim gi ti nguyn ca cc dch v. Giao thc RSVP c 2 bn tin c bn: bn tin Path v bn tin Resv. 2 router s da vo cc thng s trong 2 bn tin ny quyt nh vic thit lp kt ni gia chng hay khng.RSVP s dng hai bn tin PATH v RESV xy dng LSP vi mc cht lng dch v theo yu cu nhng ng i ca bn tin PATH v RESV l ng nh tuyn tng minh ( explicit route).

1. Bn tin PATH: Vi giao thc RSVP m rng, bn tin PATH c thm mt thnh phn mi: ERO ( explicit route object). Sau y, chng ta tm hiu v ba thnh phn chnh ca bn tin PATH: Thnh phn yu cu nhn( Label request object) Thnh phn nh tuyn xc nh( Explicit route object) Thnh phn nh tuyn mnh tin ( Record route object) Thnh phn yu cu nhn ( LQO) :Igress LSR yu cu n nh nhn cho LSP cn x l, ngoi ra thnh phn cn mang gi tr m nhn dng giao thc lp mng L3PID ( Layer 3 protocol identifier) xc nh giao thc lp mng s dng. C 3 loi nhn c s dng:Nu giao thc lp 2 khng c cu truc xc nh th nhn c dng l nhn chn thm (shim label) nm gia tiu lp 2 v lp 3.Nu giao thc lp 2 l ATM th gi tr nhn cha trong vng thng tin VCI v VPINu giao thc lp 2 l Frame Relay th nhn c cha trong vng DLCI.Khi nhn c bn tin PATH, cc LSR s gi li trong khi trng thi ng dn ( Path State Block) dnh cho LSP ny. Nu xch nh c loi nhn th s tin hnh qu trnh n nh nhn.Cc li c th xy ra: LSR nhn c bn tin PATH nhng khng n nh c nhn th n s gi bn tin PATH Error bo vi igress LSR bit xy ra li nh tuyn hoc li ca n nh gi tr nhn. Nu LSR nhn c khng h tr L3PID th s gi PATH Err cho igress LSR. Li ny xy ra s kt thuc qu trnh khi to LSP. Nu nhn c bn tin ny m khng nhn ra c thnh phn yu cu nhn (Label request object) th cng gi PATH Err v kt thc khi to LSP. Thnh phn nh tuyn xc nh ( ERO):Thng tin trong thnh phn ny l ng i cua bn tin PATH trong mng. Cc LSR cn c vo thnh phn ny chuyn bn tin n ch nhn tip theo trong mng. ERO ch s dng unicast v ch khi tt c cc b nh tuyn trn ton tuyn u h tr RSVP v ERO.Cu trc ca ERO gm mt chui cc thnh phn ph ( subobject). Mi thnh phn ny xc nh mt nhm cc nt mng hay ch l mt nt mng trn ng nh tuyn hoc ch ra mt thao tc trn tuyn. Mi thnh phn ph nh th c gi l abstract node v nu ch c duy nht mt nt mng th gi l Simple Abstract Node. Cc thnh phn ph trong mt ERO c th l nhng ch s AS ( Autonomous System), trong mi AS c th c nhiu nt mng nhng chng hon ton trong sut i vi igress LSR. Di y l nh dng ca mt thnh phn ph trong ERO:Bit LLoi(Type) di(Length)Ni dung thnh phn ph( Subobject content)

Bit L =1: l mt ghp lng ( loose hop) L =0: l mt ghp cht (strict hop) trn ng nh tuyn xc nh ( explicit route).C 4 loi thnh phn ph (subobject) c nh ngha: Ipv4: cc nt mng trong abstract node c a ch IP thuc phin bn 4. Mi a ch c 32 bit. Ipv6: a ch ca mi nt mng thuc phin bn 6, 128 bit. Autonomous System Number: nhng nt mng nm trong abstract node cng nm trong mt AS. Thnh phn nh tuyn mnh tin ( RRO):Vi thnh phn ny trong bn tin PATH, LSR s bit c tt c cc LSR nm trn ng i cua bn tin PATH ( cng chnh l LSP) t igress LSR n egress LSR. Khi igress LSR xy dng mt LSP, u tin, n s gi i bn tin PATH c cha thnh phn Label object v c thnh phn RRO. Thng tin cha trong RRO lc ny ch c a ch IP ca igress LSR.Khi mt LSR trung gian nhn c bn tin ny, LSR s sao li thnh phn RRO trong khi trng thi ng dn ( Path state block) v thm a ch IP ca n vo trong thnh phn RRO. Ring egress LSR khi nhn c bn tin PATH s hi p li bng bn tin RESV. Bn tin ny s sao li thnh phn RRO ca bn tin PATH. Nh vy, sau qu trnh trao i bn tin PATH v RESV, mi LSR s bit c ton b LSR thuc LSP ny. iu ny rt hu ch cho cng vic qun tr mng.

2. Bn tin RESV:Bn tin ny dc egress LSR gi i tr li bn tin PATH. Bn tin RESV mang thng tin v gi tr nhn c n nh cng nh ti nguyn mng c dnh cho LSP ny. Thnh phn chnh nhn ( Label object).

Thnh phn Label Object trong bn tin RESVKhi nhn c mt bn tin RESV, LSR s kim tra xem bn tin ny tng ng vi bn tin PATH no v LSR gi c phi l nt mng k tip thuc LSP hay khng. Khi tt c u hp l th LSR s n nh gi tr nhn trong bn tin RESV cho vng nhn u ra (outgoing label). ng thi LSR cng gi i bn tin RESV vi gi tr nhn s dng cho LSP ny ti LSR ngc dng.Nh vy khi igress LSR nhn c bn tin RESV, lung lu lng xc nh c LSP dnh cho n. Qu trnh n nh nhn cho LSP c thc hin di hnh thc downstream on demand.

3. Qu trnh gi bn tin PATH:Ti LSR 1: LSR 1 gi i bn tin PATH v ba thnh phn chnh trong bn tin PATH:Explicit route: m t ng i ca bn tin PATH trong mng xy dng LSP v dnh sn ti nguyn mng trn LSP ny.Label request: a ra yu cu v gi tr nhn dnh cho LSP.Record route: thnh phn ny trong bn tin gip igress LSR c c thng tin chnh xc v LSP nh a ch ca cc LSR thuc LSP. Thnh phn ny rt thit thc trong vic khc phc hin tng lp vng.Ti LSR 2:Khi nhn c bn tin PATH, LSR 2 lu thnh phn Label request v Explicit route trong khi trng thi ng dn ( Path state block). ng thi a ch IP ca LSR gi LSR 1, session, tpec cng c lu li s dng cho vic nh tuyn bn tin RESV tng ng vi LSR 1.Cn c vo thnh phn Explicit route, LSR 2 chuyn bn tin PATH n LSR 3.Trong trng hp khng th n nh nhn cho LSP, LSR 2 s gi bn tin PATH Err bo li n LSR 1Ti LSR 3: Qu trnh tng t nh LSR 2.Ti LSR 4: Nhn c bn tin PATH, LSR 4 it c n chnh l egress LSR v tin hnh gi bn tin RESV v LSR 1.

4. Qu trnh gi bn tin RESV:

Ti LSR 4:LSR 4 n nh gi tr nhn bng 0 cho LSP, a gi tr nhn ny vo thnh phn Label ca bn tin RESV. L do LSR 4 s dng gi tr nhn bng 0 l khi nhn gi d liu c nhn bng 0, LSR 4 s bit c n l egress LSR ca LSP, g nhn v nh tuyn gi bng cc giao thc nh tuyn IP truyn thng.LSR 4 s dng thng tin Sender_Tpec ( Traffic Specification ) to ra thnh phn Receiver_Tpec ( Request Specification). ng i ca bn tin RESV c xc nh da vo thng tin lu li trong khi trng thi ng ( Path state block).

Ti LSR 3:Nhn c bn tin RESV, LSR 3 c thng tin trong thnh phn Label, lu gi tr nhn bng 0 v vng nhn u ra ( Label out ) trong bng LIB. Vi nhng gi d liu n LSR 4 trn LSP ny, LSR 3 s gn vo gi gi tr nhn bng 0.LSR 3 s n nh mt nhn thch hp cho LSP ny. y, nhn ny bng 20, gn gi tr ny vo bn tin RESV v gi n LSR 2.Ti LSR 2: Qu trnh tng t nh LSR 3, v nhn c gn bng 10.Ti LSR 1:Khi nhn c bn tin RESV, qu trnh xy dng LSP kt thc. Vi nhng lung lu lng thch hp, LSR 1 s gn nhn bng 10 cho cc gi d liu chuyn ti LSR 2.B. M PHNG BNG PHN MM GNS3:I. THC HIN MT S HOT NG TRN LSP:1. Cch thit lp 1 LSP:Ta cu hinh nh sau: Router#configure terminal Router(config)#interface tunnel {number}2. giai phong 1 LSP: Router#configure terminal Router(config)#interface tunnel {number} Router(config-if)shutdown3. thay i thuc tinh cua LSP :Ta cu hinh nh sau: Router#configure terminal Router(config)#interface tunnel {number}Cu hnh a ch cng ca ng hm l cng Loopback: Router(config-if)#ip unnumbered loopback {number}Cu hnh a ch ch ca ng hm: Router(config-if)#tunnel destination {ip address}Cu hnh ch hot ng ca ng hm: Router(config-if)#tunnel mode mpls traffic-engCu hnh thng s bng thng cn thit cho ng hm Router(config-if)#tunnel mpls traffic-eng bandwidth {kbps}Cu hnh c thuc tnh phn lp ti nguyn cho ng hm Router(config-if)#tunnel mpls traffic-eng affinity {0x0-0xFFFFFFFF} mask{0x0-0xFFFFFFFF}Cu hnh thng s u tin cho ng hm Router(config-if)#tunnel mpls traffic-eng priority {setup priority-value} {hold priority-value}Cu hnh ty chn thit lp ng hm (ng hoc tng minh)Router(config-if)#tunnel mpls traffic-eng path-option {priority} {dynamic| explicit {name {LSP name} } }Nu ty chn thit lp ng hm l tng minh th ta phi ch r a ch IP ca cc Router m ng hm s i qua. Router(config)#ip explicit-path name {LSP name} enable Router(cfg-ip-expl-path)#next-address {ip address} Router(cfg-ip-expl-path)#next-address {ip address}

4. Tai inh tuyn:Di y la hinh:Ta gia s ta co tuyn tng minh R1-R4-R5-R3 . nhng lin kt gia R4-R5 gp s c. tranh trng hp mt nhiu thng tin trong thi gian do tim lai ng i ta s dung ng d phong R4-R2-R5

ng mau xanh la la ng hm tng minh a inh tuyn R1-R3ng mau xanh dng la ng d phong khi lin kt gia R4-R5 gp s c kich hoat ch bao v lin kt ta dung lnh sau:tunnel mpls traffic-eng fast-rerouteCu hinh R1Cu hinh R4 trng hp gia s bao v lin kt gia R4=R5

Va kt qua khi ta kim tra ln R4

Khi ta shutdown cng S1/1 cua R4 va ta thy tunnel 2 vn hoat ng

Kim tra ng ng i cua tunnel 2 ta se thy no i theo con ng R1-R4-R2-R5-R3

II. CU HNH TUYN TNG MINH CHO 1 LSP V THIT LP TH T NHNG CON NG VT L H TR CHO 1 LSP:

y ta thit lp mt LSP i t R1 n R3 vi 3 con ng vt l h trCu hnh LSP t R1 n R3 vi path-option 1 l tuyn tng minh i t R1-R2-R3-loopback 3.3.3.3,path-option 2 l tuyn tng minh R1-R4-R5-R3-loopback 3.3.3.3,v path-option 3 l tuyn ng .Cu lnh cu hnh nh sau:R1(config)#interface tunnel 1R1config-if)#ip unnumbered loopback0R1 (config-if)#tunnel destination 3.3.3.3R1 (config-if)#tunnel mode mpls traffic-engRouter(config-if)#tunnel mpls traffic-eng bandwidth 600R1 (config-if)#tunnel mpls traffic-eng affinity 0x1mask0x1R1 (config-if)#tunnel mpls traffic-eng priority 2 2R1 (config-if)#tunnel mpls traffic-eng path-option 1 explicit name tm1R1 (config-if)#tunnel mpls traffic-eng path-option 2 explicit name tm2R1config-if)#tunnel mpls traffic-eng path-option 3 dynamicR1config-if)#tunnel mpls traffic-eng autoroute announce y v ta cu hnh path-option 1,2 l tuyn tng minh nn tip theo ta cu hnh a ch ip ca router m ng hm s i qua:R1 (config)ip explicit-path name tm1 enableR1 (cfg-ip-expl-path)#next-address 10.0.1.2R1 (cfg-ip-expl-path)#next-address 10.0.2.3R1 (cfg-ip-expl-path)#next-address 3.3.3.3

R1 (config)ip explicit-path name tm2 enableR1 (cfg-ip-expl-path)#next-address 10.0.3.4R1 (cfg-ip-expl-path)#next-address 10.0.4.5R1 (cfg-ip-expl-path)#next-address 10.0.5.3R1 (cfg-ip-expl-path)#next-address 3.3.3.3Kim tra kt qu:R1 (#)show mpls traffic-eng tunnels tunnel 1

By gi ta to ra 1 s s c thy r th t u tin cc con ng vt l nh trong m phng l path-option 1 >path-option 2>path-option 3TH1: Thay i bng thng trn lin kt gia R2 R3 xung cn 500,nh vy lc ny bng thng trn lin kt ny khng cn p ng cho tunnel 1 i qua nn tunnel s i theo con ng path-option 2

TH2: Ta shutdow lin kt gia R5v R3 cho n khng i theo con ng path-option 2 na m chuyn qua i con ng ca path-option 3

III. CHO PHP HOC KHNG CHO PHP TI TI U MT LSP ANG HOT NG:Cc c trng, trng thi mng c th bin ng theo thi gian. Do , cc LSP c thit lp trc l ti u nht nhng thi im hin ti th c th n khng cn l ti u na. V th, mun duy tr mng trng thi ti u nht th phi thc hin ti ti u ha Reoptimization.Chng ta i vo tng dng ti ti u c th nh sau:1. Ti ti u theo nh k - Periodic reoptimization:Trong thi gian vn hnh mng, c th xy ra cc trng hp nh: cc ti nguyn mi tr nn kh dng, cc ti nguyn b li c ti kch hot, cc ti nguyn c cp pht i by gi c thu hi livvTi ti u theo nh k cho php sau nhng khong thi gian nht nh, MPLS-TE thc hin vic kim tra li ng ti u nht cho cc ng hm LSP.Mc nh khong thi gian ny l 1 gi (3600 giy).V d: Xt ng hm t R1 n R3. Trc y bng thng ca lin kt R2-R3 l 200kbps, by gi c nng cp thnh 1000kbps. Ta s xt qu trnh ti ti u ca mng.

t bng thng lin kt R2-R3 l 200kbps (trn Router2)

Hin th LSP (trn Router1)

Nng cp bng thng ln 100kbps:

Thit lp ti ti u theo nh k (trn Router1):

y ta t chu k l 10 giy c th thy ngay c kt qu.Sau kim ra li LSP mi c ti ti u:

2. Ti ti u ha th cng - Manual Reoptimization:Ta xt v d nh trn. Vi chu k ti ti u mc nh ca h thng l 1 gi. Nu ngi qun tr mng mun LSP c ti u ngay ti thi im bng thng c nng cp m khng phi ch 1 gi th thc hin cu lnh nh sau:

Kim tra li LSP mi c ti ti u:

3. Ti ti u theo s kin - Event-Driven Reoptimization:V d: Xt mt LSP t R1 n R3. t gi thit rng lin kt gia R2-R3 trc y b Down nhng gi c kch hot tr li. Ta tin hnh m phng nh sau:

Shutdown lin kt R2-R3 (trn Router2):

Hin th LSP trn Router1:

Bt li lin kt R2-R3:

Thit lp ti ti u theo s kin Link uptrn Router1:

Sau kim ra li LSP mi c ti ti u:

4. Tt chc nng ti ti u:Trong trng hp ngi qun tr mng khng mun thay i LSP d trong bt k trng hp no th dng cu lnh nh sau:

Khi LSP s lun l ng nh thit lp ban u:

IV. CH RA NHNG LP TI NGUYN C BAO GM HOC LOI TR TRONG THIT LP MT NG VT L CHO MT LSP:

Affinity bit : l thuc tnh dng iu khin cc lin kt, cho php p t cc chnh sch bng cch bao gm hay loi tr mt s lin kt no .Thuc tnh Affinity c dng chui bit nh sau: Affinity bit (32 bits), Mask(32 bits).Mask ch nh bit no trong lp ti nguyn cn c kim tra.

Attribute flag : (c thuc tnh) ch ra lp ti nguyn, kh nng hay chnh sch qun tr ca lin kt. C thuc tnh bao gm 32 bit, mi bit c thit lp theo mc ch ca ngi qun tr. V d : bit ny c th ch lin kt ny c tr nh hn 100ms, cn bit khc c th ch lin kt c tc caoLin kt c cho php s dng nu chui Affinity bit ca TE-LSP trng vi Attribute flag sau khi cng thc hin php AND vi Mask. Gi tr mc nh ca Mask l 0x0000ffffTrong MPLS TE, vic thay i cc gi tr Mask, Affinity bit v Affinity flag c nh hng ti vic iu khin lu lng v ng i ca cc bn tin trong mt tunnel. Sau y s xet ba trng hp thy c s nh hng . Trc ta cu hnh tt c cc lin kt vi thng s mark = 0x1, Affinity bit = 0x1, Attribute flag = 0x1 v cu hnh mt tunnel t R1-R3 th tunnel c th i qua lin kt ny vi con ng nh sau:

Da vo bng ta thy vi cc thng s cu hnh nh vy th tunnel c th i qua c cc lin kt v ti R3 thng qua R2. y cng l con ng ngn nht h thng tm c.

TH1: Thay i cc gi tr ca Attribute flag ti cc lin kt R1- R2 , R2-R3, R4-R5 thnh 0x2 cn cc lin kt khc vn gi nguyn.

Ta thy bn tin khng cn i theo ng c na m chuyn sang con ng khc l qua R1-R3-R6-R7-R5 mc d con ng ngn nht vn l qua R1-R2-R3. Bi v,khi thay i c thuc tnh cc lin kt ln 0x2 v gi tr Mask v Affinity bit vn l 0x1 th lc ny thuc tnh ca tunnel ch bao gm bit 1 cui dy bit (0000 0001)(xt 8 bit cui ) v h thng ch xt ti v tr bit ny. Cn ti cc ln kt c c thuc tnh 0x2 th lp ti nguyn bao gm l ti bit k bit cui (0000 0010). Nh vy l gi tr Affinity bit v Mask ca tunnel khng tha mn gi tr Attribute-flag nn khng th i qua con ng c m phi tm con ng khc di hn nhng c gi tr tha mn.

TH2: R1-R2 = 0x5R2-R3 = 0x5Cc lin kt cn li bng 0x1Mask ca tunnel bng 0x3 v Affinity bit bng 0x1

Tunnel i qua cc router R1-R2-R3 v gi tr Affinity bit v Mask tha mn gi tr Affinity flag trn lin kt. Trn lin kt R1-R2-R3 c Affinity flag= 0x5 (0000 0101) v tunnel c Mask = 0x3(0000 0011), Affinity bit= 0x1(0000 00001). Khi ta ci t thng s nh vy th h thng tnh ton theo cch da vo gi tr Mask(0000 0011) h thng ch so snh hai bit cui ca Affinity flag trong lin kt vi 2 bit cui Affinity bit trong tunnel nu bng nhau th lin kt cho php s dng. Trong trng hp ny 2 bit cui ca Affinity flag v Affinity bit bng nhau v bng 01. Mt khc y cng l con ng ngn nht m h thng tnh ton nn con ng ny l ti u nht bn tin i qua.

TH3: Lin kt R1-R2= 0x6,R2-R5 = 0x6, R5-R3= 0x6Tunnel c Affinity bit = 0x4, Mask = 0x5Cc lin kt khc bng 0x1Ta c:

Phn tch thy Mask = 0000 0101 nn h thng s so snh hai bit v tr bit th 6 v th 8 ca Affinity bit(0000 0100) v Affinity flag(0000 0110) thy hai bit ny ca c hai u ging nhau v bng 01 nn cc lin kt ny cho php tunnel i qua.Qua cc trng hp trn ta nhn thy s nh hng ca gi tr c thuc tnh, mt n Mask v Affinity bit ti vic iu khin lu lng i trong mt tunnel. T chung ta c th tnh ton gi tr thch hp ca cc thnh phn trn chn c con ng ti u nht c th.

Lu : Khi tnh ton gi tr ca mt mask th phi xt xem gi tr Affinity bit c bit 1 nm v tr no chn gi tr thch hp.V d: Nu chn Affinity bit = 0x1 m chn Mask = 0x4 th h thng s cho cnh bo

V. THIT LSP THEO TH T U TIN V XC NH S LN CHIM DA VO U TIN CA LSP:1. Thit k 1 LSP theo 1 th t u tin:Ban u ta c hnh v cc thng s TE, bng thng v c thuc tnh cu cc lin kt u nh nhau nh sau:

Trn R1 ta ro 1 ng hm t R1 n R3 nh sau:

R1 (config)#interface tunnel 1 R1 (config-if)#ip unnumbered loopback0 R1 (config-if)#tunnel destination 3.3.3.3 R1 (config-if)#tunnel mode mpls traffic-eng R1 (config-if)#tunnel mpls traffic-eng bandwidth 100 R1 (config-if)#tunnel mpls traffic-eng affinity 0x1 mas k0x1 R1 (config-if)#tunnel mpls traffic-eng priority 7 7 R1 (config-if)#tunnel mpls traffic-eng path-option 1 dynamic R1 (config-if)#tunnel mpls traffic-eng autoroute announce

Ta dng lnh show mpls traffic-eng tunnels tunel 1 xem ng i ca ng hm tunnel 1

Ta thy ng hm i theo ng R1 - R2 -R3 v con ng ny l ti u nht c tng TE nh nht (TE=2), bng thng v c thuc tnh u nh nhau.2. Xt s nh hng ca TE metric:By gi ta thay i TE trn on t R1 n R2 l TE=3TE ca R1-R2-R3 lc ny l 4, TE ca R1-R4-R5-R3 l 3

R1(config)#interface s1/0 R1(config-if)#mpls traffic-en administrative-weight 3Ta kim tra li ng hm bng lnh: R1r#show mpls traffic-eng tunnels tunnel 1Tunnel 1 i theo ng R1-R4-R5-R3 v c tng ch s TE metric nh hn ( TE=3).Vy ng no c tng s TE nh hn s c u tin hn.3. Xt s nh hng ca bng thng:

Ta thay i bng thng ca lin kt R4-R5 l 500, lin kt l R2-R3 l 500 v gi nguyn TE thay i nh sau:

R4(config)#interface s1/2 R4(config-if)#ip rsvp bandwidth 500 R2(config)#interface s1/1 R2(config-if)#ip rsvp bandwidth 500V kim tra kt qu:

Ta thy Tunnel 1 i theo con ng R1-R4-R2-R5-R3 v ta cu hnh bng thng cho Tunnel l 800kbps m lin kt R4-R5, R2-R3 bng thng ch bng 500kbps nn khng Tunnel 1 i qua nn Tunnel 1 chn con ng c bng thng v c TE nh hn i qua.4. Vn ln chim:Ta gi nguyn cc thng s ca cc lin kt nh trn. Trn R1 to mt ng hm khc tunnel 2 c ch l R3, bng thng 800kbps, c thuc tnh 0x1, ch s u tin 6 so vi tunnel 1 l 7: R1 (config)#interface tunnel 2 R1 (config-if)#ip unnumbered loopback0 R1 (config-if)#tunnel destination 3.3.3.3 R1 (config-if)#tunnel mode mpls traffic-eng R1 (config-if)#tunnel mpls traffic-eng bandwidth 800 R1 (config-if)#tunnel mpls traffic-eng affinity 0x1 mas k0x1 R1 (config-if)#tunnel mpls traffic-eng priority 6 6 R1(config-if)#tunnel mpls traffic-eng path-option 1 dynamic R1(config-if)#tunnel mpls traffic-eng autoroute announceSau kim tra ng hm Tunnel 2: R1#show mpls traffic-eng tunnels tunnel 2

Ta thy Tunnel 2 i trn ng hm R1-R4-R2-R5-R3 trng vi con ng ca Tunnel 1Ta kim tra s ln chim bng lnh:

R1#show mpls trafic-eng tunnels destination 3.3.3.3 brief

Do Tunnel 2 ln chim ng hm ca Tunnel 1 nn Tunnel 1 b down v nhng ng hm cho Tunnel 2 (up)

VI. PHN TCH CC BN TIN RIB,LIB V LFIB:

1. Xem bn tin LIB :Bng cu lnh : Router#Show mpls ldb binding 3.3.3.3 subnetmask

Da vo bn tin LIB ta thy t R1 i ti R3 c th thng qua 2 con ng: Cc gi tin c ch l 3.3.3.3 mun i qua n phi c gn nhn 17. Qua R2 c a ch tunnel-ID 4.4.4.4 trn cng se1/0 c nhn l 18 Qua R4 c a ch tunnel-ID 2.2.2.2 trn cng se1/1 c nhn l 172. Xem bn tin RIB :Bng cu lnh : Router#show ip route 3.3.3.3

Da vo bn tin RIP ta thy: Phng thc nh tuyn trong mpls l ospf 1 Da vo thut ton ospf chn con ng i tt nht ti a ch 3.3.3.3 qua cng se1/0 c lp mng l 10.0.1.0 gi tin s c y ti a ch 10.0.1.2.

3. Xem bn tin LFIB :Bng cu lnh : Router#show mpls forwarding-table 3.3.3.3 subnetmask

Da vo bn tin FLIB ta thy: Khi i ti mng 3.3.3.3/32 mpls chn con ng qua se1/0 c nhn c gn bn trong l 17, v nhn c gn khi qua R2 l 17 , phng thc truyn point-to-point

4. Mi tng quan gia RIP,LIB,FLIB:

chn u tin: LIB c to nn do cc giao thc phn phi nhn, gi tin IP i vo min MPLS, Router s da vo a ch ch tm kim trong bng LIB gn nhn cho gi tin. chn k tip: Thng tin n mng c cc giao thc nh tuyn cung cp dng xy dng bng nh tuyn RIB sau RIB cung cp thng tin cho FIB. chn cui cng: Router s da vo nhn c bit gi gi tin . LIB kt hp viRIBto nn LFIB Router trong min MPLS s da vo nhn c lu trong bng LFIB xc nh nt k tip, thay i nhn v forward gi tin i.

1GVHD: Th.S NGUYN XUN KHNH