MPLS TE - Nhom Tienhung

HC VIN CNG NGH BU CHNH VIN THNG

C S THNH PH H CH MNH

KHOA VIN THNG II

-------------------------

Bo co ti:

TM HIU V MPLS TRAFFIC ENGINEERING

Gio vin hng dn : ThS Nguyn Xun Khnh

Lp : D10CQVT01-N

Nhm sinh vin thc hin :

L Quang Tm

Nguyn Tin Hng

Nguyn Vn Ninh

ng Hoi Khang

Nguyn Thnh Hoi

Ng Nguyn Huy Cng

Hunh Tin Ngha

Nguyn Trng Sang

L thuyt v MPLS Trafic Engineering Trang 1

MC LC

CHNG I TNG QUAN V MPLS TE ...................................................................................................................... 2

CHNG II PHN PHI THNG TIN TRONG K THUT LU LNG ........................................................ 7 2.1.1. Cu trc ca LSA ................................................................................................................................................................... 8

2.1.2. M t sub-TLV ...................................................................................................................................................................... 9

2.2. M rng giao thc IS-IS cho TE ............................................................................................................................................. 9

2.2.1. Cc m rng IS Reachability TLV (TLV 22) .......................................................................................................................... 10

2.2.2. M rng IP Reachebility TLV (TLV 135) .............................................................................................................................. 10

2.2.3. M rng Router ID TLV trong k thut lu lng (TLV 134) ............................................................................................... 11

2.3. Th tc lan truyn thng tin trong IGP ................................................................................................................................ 11

CHNG III C CH THIT LP V TNH TON NG I TRONG MPLS TE ...................................... 14

3.1. Tinh toan ng i ............................................................................................................................................................. 14

3.2. C ch thit lp ng i ................................................................................................................................................... 14

3.2.1. Giao thc RSVP-TE ............................................................................................................................................................. 14

CHNG IV CHUYN TIP LU LNG VO MPLS TE TUNNEL ................................................................ 27

4.1. Static routing (nh tuyn tnh) .......................................................................................................................................... 27

4.2. Policy-based routing (nh tuyn theo chnh sch) ............................................................................................................. 27

4.3. Autoroute Announce (nh tuyn t ng bng cch thng bo) ....................................................................................... 27

4.4. Forwarding adjacency (Ln cn chuyn tip). ...................................................................................................................... 27

4.5. Direct mapping of AToM trafc onto TE tunnels (Ghp trc tip lu lng ca AtoM trn cc TE Tunnel): ....................... 28

4.6. Class-based tunnel selection (la chn cc Class-based Tunnel) ......................................................................................... 28

CHNG V TI NH TUYN NHANH .................................................................................................................. 29

5.1. Fast ReRoute Tai nh tuyn nhanh.................................................................................................................................. 29

5.2. FRR- Bo v lin kt (Link Protection) ................................................................................................................................. 29

5.3. FRR Bo V Node (Node Protection) ................................................................................................................................ 32


Chng I TNG QUAN V MPLS TE

1.1. Gii thiu v MPLS TE:

K thut lu lng hay l k thut iu khin lu lng qua mng c trin khai 1 thi gian nhng

n ch yu ch hot ng trn mng ATM hoc Frame Relay. Vai tr ca TE l iu khin lu lng t 1 edge

router ny n 1 edge router khc trong mng theo cch ti u nht. Trong cc mng ny, cc mch o c

thit lp a lu lng t 1 edge router ny n 1 edge router trn chuyn mch ATM hoc Frame Relay.

Ngy nay, r rng rng IP ang l giao thc mng c s dng ph bin. Mc d trc y mng IP hot ng

da trn nn tng Frame Relay hoc ATM nhng cng ngy cng c nhiu mng hot ng trn mng thun IP

hay IP chy trn 1 mng dng MPLS. Do gii php TE cn thit cho mng IP. Mc d TE vn c th cha

chy trn 1 mng thun IP c nhng l c th trn 1 mng IP/MPLS vi gii php TE.

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 (V d: Open

Shortest Path First [OSPF] v Intermediate System-to-Intermediate System [IS-IS]), mt metric tng hp. (V

d: giao thc Gateway Routing Protocol [IGRP] v Enhanced Interior Gateway Routing Protocol [EIGRP]),

hoc n gin l ch s hop (V d: Routing Information Protocol [RIP] v RIPv2).

M hnh chuyn tip IP da trn chi ph thp nht ny chuyn tip data vo cc tuyn. Hn na, cc

gi IP c chuyn tip trn mi hop (router) da trn a ch IP ch v c lp vi cc gi tin IP c

chuyn tip trn router trc khi hoc sau khi ra khi hop ny.Ngoi ra, cc m hnh chuyn tip IP khng xem

xt bng thng hin c sn ca lin kt, trong c th khc nhau ng k so vi chi ph c gn cho cc lin

kt. do , mt router c th tip tc chuyn tip lu lng IP vo mt lin kt, mc d lin kt b mt gi

d liu do thiu bng thng chuyn tip tt c cc lung d liu m bng nh tuyn ch ra.

Kt qu ca vic s kin ny trong chuyn tip cc gi tin IP l mt s lin kt c th l nghn trong

mng, trong khi cc lin kt khc c th khng c s dng ng mc. Tt nhin, ta c th ch n t l lu

lng truy cp trn cc lin kt ca mng v lp k hoch nng cp h thng thch ng vi lu lng. Thm

bng thng cho cc lin kt l khng d thc hin, n cn lp k hoch v cn c thi gian. Bi v lu lng

gia cc node c th thay i hon ton bt ng v khng phi l lun lun c nh, TE c th mang li c gii

php bng cch iu khin lu lng hoc mt phn ca n i t cc lin kt qu ti.


M hnh mng chuyn tip IP

Nu tt c cc lin kt trong mng mu ny c cng chi ph, con ng chi ph thp nht t router R1

n router R5 l con ng R1-R2-R5. R rng, tt c lu lng truy cp t R1 n R5 s s dng ng dn

R1-R2-R5 v ng R1-R3-R4-R5 s khng c lu lng truy cp. Trong c mng thc s, mi th khng phi

r rng. nhiu lung lu lng c th tn ti v lung trn cc lin kt c th khc nhau rt nhiu. Ta c th

phn phi ti trng ng u hn bng tnh ton vi chi ph ca cc lin kt cho ring giao thc nh tuyn.

iu c th phn phi lu lng ng u hn, nhng ta khng th c th phn phi lu lng,hon ho, bi

v trong cc mng thc s, lin kt hu nh khng bao gi s dng cng mt bng thng. Trong mng Hnh 1.1,

ta c th m bo rng hai ng nh nhau bng cch m bo rngtng cc chi ph ca cc lin kt trong

ng dn R1-R2-R5 v ng dn R1-R3-R4-R5 u bnh ng. kt qu s l cn bng ti lu lng gia R1

v R5 trn hai con ng. iu ny s tt hn cho cc lu lng truy cp gia R1 v R5, nhng chc chn s c

lu lng truy cp vo mng trn R2 hoc R4 v nh vy. y l cng l mt vn , bi v c hai tuyn t R2

n R4, mt ch hai tuyn, hoc l ba. Ta c th c cng mt vn gia cc router R3 v R5hoc bt k

nhng router khc. Ni cch khc, vn ti cc lin kt bnh ng vi lu lng truy cp l mt vn kh

khn bi nu ta ch cn c gng iu chnh chi ph ca mi lin kt trong mng.

tng thm s phc tp ca vn , tc ca bt k lin kt c th c nng cp, cho php bng

thng ln hn trn cc lin kt nht nh. Vo thi im , ta cn phi thit lp li t u v thay i chi ph

ca cc lin kt mt cch th cng trn ton mng. iu ny r rng l khng kh thi t mt quan im hot

ng.V th, MPLS TE l mt gii php cho vn ny trong cc cch sau:

MPLS TE cung cp hiu qu truyn ca lu lng truy cp trn ton mng, trnh nghn mng v s

dng hp l lin kt.

MPLS TE xt n (tnh) bng thng cu hnh cc lin kt.

MPLS TE c cc thuc tnh lin kt vo ng truyn (v d, tr, jitter).

MPLS TE iu chnh t ng thay i bng thng v cc thuc tnh lin kt.

Ngun nh tuyn c bn cho php xy dng traffic-engineered tri ngc vi nh tuyn IP.


MPLS TE cho php mt s TE t ngun ti ch ca router l mt mt ng i chuyn mch nhn

(LSP) c th tnh ton cc tuyn ng hiu qu nht qua mng v pha ch LSP qua router.Cc router bin c

th lm iu nu n c cu trc lin kt ca mng. Hn na router bin, cn bit bng thng cn li trn tt

c cc lin kt ca mng. Cui cng, ta cn phi kch hot MPLS trn cc router ta c th thit lp LSP t

u n cui. Thc t l chuyn mch nhn l s dng v cho php chuyn tip IP cho cc ngun da trn nh

tuyn thay v ch da trn nh tuyn a ch IP ch. l bi v MPLS khng chuyn tip trong mt phng d

liu, bng cch kt hp mt nhn n trong cc c s thng tin chuyn tip nhn (LFIB) v trao i n vi mt

nhn i.V vy, router bin cp nhn nh tuyn chuyn mch (LSR) ca LSP c th xc nh nh tuyn ca

gi c nhn, sau khi tt c LSRs ng cc nhn s dng m LSP. Hnh 1.2 cho thy mtv d v m ngun

da trn kh nng ca MPLS TE nh tuyn.

MPLS TE head v end router

minh ha cho khi nim ny, router R6 v R7 c thm vo pha trc ca router R1. Gi s

router R6 v R7 mun gi lu lng truy cp n R5. Nu mng ny ch ang chy chuyn tip IP th lu lng

i theo con ng ch R1-R2-R5 v IP c thc hin mt cch c lp trn mi hop trong mng. V vy, router

R1 khng c thng tin R6 v R7, v n chuyn tip lu lng theo quyt nh chuyn tip ca ring mnh da

trn bng nh tuyn IP. R6 v R7 c th c chnh sch khc nhau, mc d. R6 c th mun gi lu lng dc

theo con ng R6-R1-R2-R5, trong khi R7 c th mun chuyn tip lu lng dc theo con ng R7-R1-R3-

R4-R5, l khng th t c trong c mng IP n gin. Nu mng ang chy MPLS, ta c th thit lp hai

ng ny nhhai LSPs khc nhau nhn hiu khc nhau c s dng. Ti router R1, nhn n khc nhau

gi tr ch ra cho d cc gi thuc v LSP vi R6 nh cc u cui hoc cc LSP vi R7. R1 sau chuyn tip

cc gi tin trn mt trong hai LSPs, nhng n khng chuyn tip gi theo ring ca mnh nh trng hp vi

chuyn tip IP n gin.

Ta c th trin khai MPLS TE trong bt k mng c LSRs. Tuy nhin, bi v bng thng v cc thuc

tnh khc ca lin kt c bit n LSR ca LSPs, nh tuyn giao thc c s dng gia MPLS TE thit b

u cui phi l mt trng thi lin kt vi giao thc nh tuyn. Vi giao thc nh tuyn c trng thi lin

kt, mi router xy dng mt trng thi ca cc lin kt ring ca mnh,m sau qung b cho tt c cc router

khc trong cng khu vc. iu ny c ngha rng tt c cc b nh tuyn trong khu vc c tt c cc thng tin


cu trc lin kt ca khu vc . Cui u LSR do c th tm ra cch t cc MPLS LSP lu lng. iu

ny cho php nh tuyn da trn ngun. LSP ny c gi l mt MPLS TE Tunnel. N khng ging nh mt

Tunnel GRE, tuy nhin. Mt Tunnel TE l theo mt hng, v mtLSP l theo mt hng, v n c cu hnh

Tunnel TE ch trn vo u cui LSR v khng da trn cui ui LSR ca LSP. Hn na, mt Tunnel TE phi

c bo hiu, trong khi mt Tunnel GRE khng c c.

Nu TE c kch hot trong mng, ta c th s dng n theo hai cch khc nhau. u tin, ta c th to

MPLS Tunnel TE gia mi cp LSRs cnh trong mng ca ta. Nh vy, ta c th iu khin tt c cc lu

lng trong mng, trnh tc nghn trong n, v cung cp cho tt c cc lu lng cc c im (bng thng,

tr, jitter,v.v) cn thit. Mt v d l MPLS VPN, ni ta c th to ra mt Tunnel TE t tt c cc router PE

tt c cc router PE khc. Th hai, ta c th kch hot MPLS TE khp mi ni trong mng nhng khng c

Tunnel TE cho n khi h l cn thit. Ta c th to ra cc Tunnel TE theo yu cu. Mt v d in hnh ca

vic ny l khi ta to ra cc Tunnel TE iu tit lu lng trn mt im nng hoc qu ti im trong mng.

Quan trng la lm th no iu khin lu lng vi cc LSPs TE thng qua mng l lm th no lp bn

lu lng vo chng.

1.2. Tng quan hot ng ca MPLS TE

1.2.1. Cc chc nng chnh ca MPLS TE:

Hn ch lin kt (gi hn lu lng trn mi lin kt c th h tr v s cc TE Tunnel c th s

dng lin kt).

Phn phi thng tin TE (do TE-kch hot giao thc nh tuyn MPLS)

S dng thut ton tnh ton ng dn (PCALC) tnh ton ng i tt nht t ngun ti ch

trn cc LSR.

Giao thc bo hiu RSVP c s dng bo hiu cc TE Tunnel trn mng.

Thc hin chuyn tip lu lng vo cc TE Tunnel

MPLS TE Buiding Blocks


Ci tn u tin c s dng ti Cisco cho MPLS TE l Routing with Resource Reservation, cn c

gi l RRR hoc R3. L do chnh c MPLS TE l nh tuyn hoc iu khin lu lng theo cc ti nguyn

hoc rng buc. Cc ngun ti nguyn l bng thng ca lin kt v mt s thuc tnh ca cc lin kt m cc

nh iu hnh ch nh. nhng thuc tnh ny c cu hnh trn cc lin kt v qung b bi cc giao thc nh

tuyn link state IGP (OSPF hay IS-IS.)

Thay v to ra mt giao thc mi truyn thng tin ny v qung b n n tt c cc LSRs, OSPF v

IS-IS c m rng phi c thm thng tin ny. Khi ta cu hnh mt Tunnel TE trn mtLSR, n tr

thnh mt u cui LSR ca Tunnel TE hoc TE LSP. Sau ta ch nh im n LSR Tunnel TE v cc rng

buc n phi tun theo.

mt ngha c la chn bi ngi qun l. V d, lin kt l mt lin kt pos vi mt tc ln hn 48 OC,

hoc lin kt l lin lc a, hoc mt lin kt m c mt s chm tr nh hn 100 ms.

Mt lin kt c th c nhiu ngun ti nguyn lin kt vi n, vi ti a l 32. cc ngun ti nguyn

ang qung b trn khp cc khu vc bt c khi no h thay i trong gi tr hoc nh k. qung b nhng thay

i ny IGP tng thch ngc. iu ny c ngha rng khng phi tt c cc b nh tuyn phi h tr

nhngthay i trc khi ta c th chy MPLS TE. B nh tuyn khng hiu nhng thay i IGP i vi TE ch

b qua chng.

1.2.2. Phn phi thng tin trong MPLS TE:

Cc router LSR trong min chuyn mch MPLS c trin khai k thut lu lng cn bit c thng tin

topo mng cng nh thuc tnh ca tt c cc lin kt trong mng xy dng mt c s d liu cho vic tnh

ton ra nhng tuyn LSP kh thi. c c nhng thng tin ny th trong mng phi s dng cc giao thc

nh tuyn link-state (nh IS-IS hay OSPF). Nhng giao thc nh tuyn link-state ny c kh nng gi thng

tin ca tt c cc lin kt ca mt router n cc router khc trong mt vng, nh vy mi router trong vng c

th tnh ton c nhng tuyn i kh thi . Giao thc nh tuyn vector khng th c s dng y bi v n

ch gi thng tin v tuyn ng m n cho l tt nht, m b qua nhng tuyn kh thi khc.

Cc giao thc nh tuyn dng Link-State (OSPF v IS-IS) c m rng cho MPLS-TE khng ch qung

b cc thng tin v lin kt thng thng m n cn mang thm thng tin rng buc ca cc lin kt trong

min MPLS nh l:

Traffic Engineering Metric: l mt tham s metric s dng cho MPLS TE, do ngi qun tr t v mc

nh TE metric bng vi IGP metric.

Maximum Bandwidth: Bng thng ti a c dng cho lin kt trn mt hng truyn. Tham s ny

thng dng cu hnh bng thng cho lin kt

Maximum Reservable Bandwidth: Bng thng c th dnh ring ti a trn lin kt, thng gi tr mc

nh nn l gi tr Maximum Bandwidth, n v l byte/s

Unreserved Bandwidth: Phn bng thng kh dng cn li cha c s dng trn lin kt.

Administrative Group: Cn c gi l lp ti nguyn (mu) cha 4 octets ca bit mask c ch nh

bi ngi qun tr mng, mi bit c thit lp tng ng vi mt mu (lp ti nguyn) gn cho

interface. Bit nh nht dnh cho group 0, ln nht dnh cho group 31


Chng II PHN PHI THNG TIN TRONG K THUT LU LNG

Cc router LSR trong min chuyn mch MPLS c trin khai k thut lu lng cn bit c thng tin

topo mng cng nh thuc tnh ca tt c cc lin kt trong mng xy dng mt c s d liu cho vic tnh

ton ra nhng tuyn LSP kh thi. c c nhng thng tin ny th trong mng phi s dng cc giao thc

nh tuyn link-state (nh IS-IS hay OSPF). Nhng giao thc nh tuyn link-state ny c kh nng gi thng

tin ca tt c cc lin kt ca mt router n cc router khc trong mt vng, nh vy mi router trong vng c

th tnh ton c nhng tuyn i kh thi. Giao thc nh tuyn vector khng th c s dng y bi v n

ch gi thng tin v tuyn ng m n cho l tt nht, m b qua nhng tuyn kh thi khc.

Cc giao thc nh tuyn dng Link-State (OSPF v IS-IS) c m rng cho MPLS-TE khng ch qung

b cc thng tin v lin kt thng thng m n cn mang thm thng tin rng buc ca cc lin kt trong

min MPLS nh l:

Traffic Engineering Metric: l mt tham s metric s dng cho MPLS TE, do ngiqun tr t v mc

nh TE metric bng vi IGP metric.

Maximum Bandwidth: Bng thng ti a c dng cho lin kt trn mt hngtruyn. Tham s ny

thng dng cu hnh bng thng cho lin kt.

Maximum Reservable Bandwidth: Bng thng c th dnh ring ti a trn lin kt,thng gi tr mc

nh nn l gi tr Maximum Bandwidth, n v l byte/s

Unreserved Bandwidth: Phn bng thng kh dng cn li cha c s dngtrn linkt.

Administrative Group: Cnc gi l lp ti nguyn (mu) cha 4 octets ca bit maskc ch nh

bi ngi qun tr mng, mi bit c thit lp tng ng vi mt mu (lp ti nguyn) gn cho

interface. Bit nh nht dnh cho group 0, ln nht dnh cho group 31.

2.1.Phn m rng ca OSPF cho TE

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 :

Gim st cc thuc tnh lin kt.

nh tuyn ngun da vo cc rng buc.

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 ( trong cc router bin )

Loi 11: qung b gia cc OSPF domain vi nhau


2.1.1. Cu trc ca LSA

LSA Header

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.

* O DC EA N/P MC E *

Trng Option

TLV Header

Gm 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.


2.1.2. M t sub-TLV

STT Tn Sub-TLV di (Octet)

1 Link Type 1

2 Link ID 4

3 Local Interface IP Address 4

4 Remote Interface IP Address 4

5 Traffic Engineering Metric 4

6 Maximum Bandwidth 4

7 Maximum Reservable Bandwidth 4

8 Unreserved Bandwidth 32

9 Administrative Group 4

Link Type: Ch ra lin kt ny l lin kt im-im hay lin kt im-a im

Link ID: Xc nh u cui ca lin kt (router ID): vi lin kt im-im th lrouter 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 kt

Unreserved 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.

2.2. M rng giao thc IS-IS cho TE

IS-IS c cc trng Type-lengh-value mi nh km trong cc thng ip PDU link-state ca n.Phn m

rng cho php IS-IS mang cc thng tin thuc tnh lin kt ca MPLS-TE.

C ba loi TLV mi:

1. u tin l m rng IS Reachability TLV hoc TLV type 22 .N l c xy dng t TLV type 2 (IS

Reachability TLV), m t nhng IS-IS neighbor ca n.

2. TLV mi th hai l m rng IP Reachability TLV (TLV type 135). N l s k tha t TLV type 128 v

130.

3. TLV 134 - Router ID TLV trong k thut lu lng.


2.2.1. Cc m rng IS Reachability TLV (TLV 22)

i vi IS Reachability TLV thng thng dnh 4 octet cho 3 metric {metric mc nh, delay, monetary

cost, reliability}. Metric mc nh thng c s dng nhng ch c 1 octet, trong mt bit ch

metric ny l metric ni vng hay ngoi vng, mt bit dnh ring v 6 bit cn li cha gi tr Metric thc

s (0-63) v th cn phi m rng gi tr metric ny.

Nh vy mt TLV thng thng cn 11 octet (4 octet metric v 11 octet System ID) nhn din mt

node lng ging th, v mt IS Reachability TLV nh vy c th cha d liu m t ca 23 lng ging.

TLV 22 ny nu khng s dng cc sub-TLV m t thm v lin kt th n vn c th cha thng tin v

23 lng ging. V di 3 octet ca metric mc nh phn bit y l thng tin tin nh tuyn ni vng

so vi 4 octet metric ca TLV 135 l metric ca thng tin nh tuyn lin vng.

Bng m t Sub TLV

STT Tn Sub di (octet)

0-2 Unassigned -

3 Administrative group 4

4-5 Unassigned -

6 IPv4 interface address 4

7 Unassigned -

8 IPv4 neighbor address 4

9 Maximum Link Bandwidth 4

10 Reservable Link Bandwidth 4

11 Unreserved Bandwidth 32

12-17 Unassigned -

18 TE metric 3

19-254 Unassigned -

255 Reserved -

V c bn, d liu sub-TLV ca IS-IS m t thuc tnh lin kt ging vi d liu sub-TLV ca OSPF.

2.2.2. M rng IP Reachebility TLV (TLV 135)

M rng IP reachability l TLV 135. N gii quyt hai vn cn tn ti ca IP Reachability TLV l:

- Mt l, IP Reachability TLV c 4 metric, nhng ch c metric mc nh c s dng thng xuyn,


nhng n b gii hn trong khong gi tr 0-63.

- Hai l vn ti phn phi tuyn. Nu cc router phn phi li IP prefixes theo c hai hng gia

mc 1 v 2 m khng cn bt k c ch b xung, router s khng th xc nh vng lp ca nh

tuyn thng tin. Khi mt router hc c mt prefix thng qua nh tuyn mc 2 v qung b prefix

xung mc 1, router mc 1 cng c th gi ngc tr li to nn vng lp. gii quyt vn

ny TLV 135 cung cp 32 bit (4 octet) cho trng default metric, v thm 1 bit up/down cho bit

rng mt Prefix c phn phi trong h phn cp.

Up/down bit

Mt m rng mi trong Reachability TLV l up/down bit, c thit lp l 0 khi mt prefix ln u tin

c a vo IS-IS. Nu mt prefix c qung b t cp cao hn n mc thp hn th bit up/down

c thit lp l 1, ch ra rng cc prefix c th i xung h phn cp.Tin t c bit up/down l 1 ch c

th qung b xung mc thp hn.

Nu mt prefix c qung b t vng ny sang vng khc cng cp, bit up/down cng c thit lp

l 1 (tnh trng ny pht sinh khi mt router ng vai tr nh nhiu b nh tuyn o gia cng cp

nhng trong cc vng khc nhau.)

M rng IP reachability TLV vi cc sub-TLVs

Mt bit cho thy s hin din ca Sub-TLV. Khi bit ny l 0 tc khng c Sub-TLV, nu bit ny l 1

octet u tin sau tin t c hiu l chiu di ca sub-TLV lin kt vi tin t IPv4 ny

2.2.3. M rng Router ID TLV trong k thut lu lng (TLV 134)

Router ID TLV trong k thut lu lng l TLV 134.

TLV Router ID cha 4 octet ID ca router ngun trong LSP. iu ny h tr trong nh tuyn d dng

hn:

-i vi k thut lu lng, n m bo rng n a ch lun lun c tham chiu n, khng ph

thuc vo trng thi ca giao din ca nt.

- Nu OSPF cng ang hot ng trong phm vi, k thut lu lng c th tnh ton nh x gia cu

trc OSPF v IS-IS.

Nu mt router khng trin khai k thut lu lng, n c th thm hoc b qua TLV Router ID. Nu

mt router thc hin k thut lu lng, n phi s dng TLV ny cho TE-LSP ca n.

Nu mt router n qung b prefix thng qua Border Gateway Protocol (BGP) th TE Routed ID nn l

BGP router ID.

2.3. Th tc lan truyn thng tin trong IGP

Giao thc nh tuyn ni vng (IGP) s lan truyn thng tin v TE trong cc trng hp sau:

1) Thay i trng thi lin kt.

2)Thay i cu hnh kt ni.

3) Lan truyn theo chu k: c s dng vi chu k lan truyn mc nh l 3 pht. v khi lin kt c s thay

i nh v bng thng dnh ring th n s khng lan truyn ngay s thay i ny ra ton mng.


4) S thay i ca bng thng dnh ring: Khi c s thay i th router s khng lan truyn ngay thng tin

thay i ny ngay nu nh s thay i v bng thng cha vt ngng thit lp. C 2 ngng

thay i l:

Ngng ln khi bng thng dnh ring tng ln mc nh l 15, 30, 45, 60, 75, 80, 85, 90,

95, 97, 98, 99 v 100

Ngng xung l khi bng thng dnh ring gim: 100, 99, 98, 97, 96, 95, 80, 75, 60, 45, 30,

15.

Khi thit lp tht bi mt ng hm: Headend-LSR c gng thit lp mt tuyn LSP m n tnh

ton bng bn tin RSVP. Tuy nhin vic thit lp c th tht bi nu c mt ng TE-LSP khc chim

bng thng ca lin kt m tuyn TE ban u i qua v th khng bng thng cn thit cho n, m s

thay i bng thng ny khng c thng bo do cha vt ngng. v vy khi vic thit lp tht bi

router trung gian s lan truyn thng tin mi. Headend-LSR s cp nht d liu v tnh ton mt

ng i khc.

2.4. nh tuyn v chi ph ca TE-LSP

2.4.1. Thuc tnh 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 hay khng. Cc lin kt c nhng cu hnh c tnh nh sau:

Bng thng dnh ring ln nht (Maximum reservable bandwidth): l bng thngdnh ring ln nht

trong phn dng chung, phn m cc ng TE thng thng c th s dng.

C thuc tnh (Affinity flag): ch ra lp ti nguyn, kh nng hay chnh sch qun trca lin kt. C

thuc tnh Affinity gm 32 bit, mi bit c th c thit lp theo mc ch ca ngi qun tr. V d

bt ny c th ch lin kt ny c tr nh hn 100ms, cn bit khc ch lin kt c tc cao,

TE metric: hay cn gi l trng s qun tr (Administrative Weight).MPLS TE sdng TE metric

ca lin kt nh tuyn TE-LSP v mc nh TE metric bng IGP metric. C th thay i TE

metric khc vi IGP metric c chnh sch chn ng tt hn. V d: IGP metric dng phn

nh nhng tuyn ng i c bng thng ln ph hp vi lu lng d liu, cn TE metric phn nh

nhng tuyn ng c tr thp ph vi vi lu lng voice.

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 d phng FRR

Bng thng sub-pool dnh ring ln nht: l bng thng dnh ring cho nhng dch vphn bit

(DiffServ-aware). N l mt phanh mnh ca bng thng dng chung.

2.4.2. Thuc tnh ca trung k MPLS TE

o Bao gm:

a ch ch ca TE-LSP: l MPLS TE router ID ca tailend-LSR, im ch ca LSPnh tuyn ti.

Bng thng mong mun: l bng thng yu cu ca TE-LSP

Affinity bit: thuc tnh ny iu khin TE-LSP s dng cc lin kt, cho php p tcc chnh sch

chn ng bng vic bao gm hay loi tr mt s lin kt no . Thuc tnh Affinity c dng chui

bit nh sau: Affinity (32bits), Mask (32 bits). Mask ch nh cc bit no trong lp ti nguyn cn c


kim tra. Lin kt c php s dng nu chui Affinity bit ca TE-LSP trng vi Affinity Flag ca lin

kt sau khi cng thc hin php AND vi Mask. Gi tr mc nh ca Mask l 0x0000FFFF.

u tin thit lp v cm gi (Setup and hold Priority): lc ch u tin cho mt sng 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 ti nguyn ca n nhng li cho ng hm quan trng hn. V d: Khi c

mt TE-LSP khc n cnh tranh bng thng trn lin kt vi TE-LSP ban u th Setup Priority ca

TE-LSP mi c so snh vi Hold Priority ca TE-LSP c, nu c u tin cao hn (ch s nh hn)

th TE-LSP mi s c u tin thit lp v TE-LSP c phi nhng li ti nguyn.

Ti ti u ha (Reoptimization): c trng ca mng l bin ng theo thi gian, v dc thm cc ti

nguyn mi kch hot, nhng lin kt b s c c phc hi, cc ti nguyn dnh ring trc thu hi

v vy khi cc ti nguyn thay i trng thi th cc LSP thit lp trc khng cn l ti u nht na

nn lun duy tr trng thi ti u nht ca LSP th cn thc hin ti u ti ha li. C th thc hin

theo ba c ch sau:

1) Ti ti u theo chu k: chu k ti ti u c th thay i t 0 n 168 gi, mc nh l 1 gi. Chu

k bng 0 tc l khng s dng chc nng ny.

2) Ti ti u theo s kin: khi mt lin kt c khc phc s c v quay tr li trng thi up.

3) Ti ti u th cng: ti ti u li ngay khi c yu cu .Ty chn thit lp ng (Path setup

option): ta c th thit lp mt tuyn TE-LSP theohai cch l: tuyn tng minh v tuyn ng.


Chng III C CH THIT LP V TNH TON NG I TRONG

MPLS TE

3.1. Tnh ton ng i

PCALC l mt thut ton SPF m MPLS TE s dng. SPF l thut ton m OSPF v IS-IS dng tnh

ton tuyn ng ngn nht n im ch. SPF iu khin trn mi router v n dng database ly t OSPF

hoc IS-IS lc ra bng nh tuyn. Bi v OSPF v IS-IS c m rng v kh nng phn phi ti nguyn

nn PCAL c th tnh ton ng truyn khng ch da vo ng i ngn nht m cn da vo ti nguyn ca

n. Lc thut ton SPF tr thnh thut ton CSPF. V c bn, khi SPF c xy dng th nhng lin kt no

khng c bng thng hoc khng p ng c yu cu v ti nguyn s b loi b. Kt qu thu c ca

thut ton CSPF khng phi l mt bng nh tuyn m l mt tuyn ng. Tuyn ng ny l mt tuyn

tng minh gm mt dy cc a ch IP, mi a ch IP i din cho mt cng giao tip trn mt router. Tuyn

tng minh ny c dng thit lp TE LSP. PCALC xy dng duy nht mt tuyn ng, khng bao gi c

2 hoc nhiu hn. V vy, iu quan trng l phi chn c mt tuyn ng tt nht trong trng hp cc

tuyn ng u c th p ng c yu cu. Nu nhiu tuyn ng c cng chi ph (cost) v tho mn iu

kin rng buc th s chn tuyn ng c bng thng ti thiu ln nht. Nu cc tuyn ng u tt v c

bng thng ti thiu ln nht u bng nhau, tuyn ng no c t s hop nht s c chn. Nu 2 trng hp

trn u tho th Cisco IOS s chn ngu nhin mt tuyn ng.

3.2. C ch thit lp ng i

Sau khi tm ng dn bng thut ton CSPF v v chng ta s dng k thut MPLS chuyn tip gi nn

vic tip theo cn lm l xy dng LSP cng vi dnh sn ti nguyn mng trn ng dn .C hai giao thc

thc hin cng vic ny: giao thc RSVP m rng v giao thc CR-LDP.

3.2.1. Giao thc RSVP-TE

3.2.1.1.Giao thc RSVP m rng:

Vi giao thc RSVP, LSP c xy dng trn ng dn m giao thc nh tuyn Ip truyn thng xch

nh. Khi mt Router trong mng nhn c bn tin PATH, router s kt hp thng tin trong bng nh tuyn,

c xy dng bng cc giao thc nh tuyn nh OSPF, IS-IS v a ch ch trn gi d liu IP xc nh

b nh tuyn tip theo nhn bn tin ny.

Cn giao thc RSVP m rng vn 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). Di y chng ta xem xt cu trc ca hai bn tin PATH v RESV.

a.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. Nh ta

bit, c 3 loi nhn c s dng:

Nu giao thc lp 2 khng c cu trc 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 VPI

Nu 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

thc 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 ca 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 L Loi

(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 ca 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.

b. 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. Trong phn ny, chng ta ch xem xt thnh

phn chnh nhn ( Label object).

Thnh phn Label Object trong bn tin RESV

Khi 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.

c. Qu trnh xy dng LSP:


nh tuyn IP truyn thng xc nh ng i ca d liu t igress LSR ( LSR 1) n egress LSR ( LSR

4) s qua mt nt mng trung gian l Router A. Trong khi , nh tuyn c rng buc xc nh hng nh

tuyn xc nh ( explicit route) cho d liu t LSR 1 n LSR 4 qua cc nt mng trung gian l LSR 2 v LSR

3. Sau y l qu trnh xy dng LSP trn tuyn nh tuyn ny.

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 1

Ti 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.


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.

ng i ca gi d liu t igress LSR n egress LSR

Di y l qu trnh di chuyn trn LSP ca cc gi d liu sau khi kt thc qu trnh n nh nhn.


LSR 1 l igress LSR, nhn cc gi d liu IP. Da vo thng tin trn tiu IP, LSR 1 nh dng li gi

d liu ph hp vi k thut lp lin kt d liu, gn nhn bng 10 v chuyn n LSR 2 trn int 2.

Nhn c d liu trn int 1 c nhn bng 10, LSR 2 da vo LIB xc nh c gi tr nhn u ra.

Trn hnh cho thy LSR 2 gi d liu c nhn bng 20 trn int 2 n LSR 3.

Qu trnh x l d liu ti LSR 3 hon ton tng t nh ti LSR 2. D liu c gi n LSR 4 trn int

2 vi gi tr bng 0.

Nhn c d liu, vi gi tr nhn bng 0, LSR 4 bit rng n l egress LSR. LSR 4 g nhn trn gi

d liu v nh tuyn bng cc thc nh tuyn IP truyn thng.

3.2.1.2.Giao thc ginh trc ti nguyn RSVP-TE:

Nhu cu s dng RSVP bt u t vic s dng mng IP vn chuyn cc lu lng thi gian thc nh

VoIP, Video Conference vn yu cu cht ch v rng buc thi gian thc. m bo yu cu, cc ng dng

s c t trc ti nguyn, tc ti nguyn khi ny s c dnh ring cho ng dng. RSVP nh ngha cch

t trc ti nguyn ny.

Nu yu cu ng k ti nguyn n bn gi v vic ng k QoS c thit lp ti mi router trn

ng i th trnh ng dng c th gi gi n bn nhn. B phn loi v b iu phi ti mi router gip cc

gi c chuyn i theo ng QoS c yu cu. Vic ng k ti nguyn ch hp l khi tt c cc router trn

ng i cung cp RSVP. Nu c mt router cung cp vic ng k ti nguyn th dch v khng th m bo

cho c ng i. Mt router trn ng i khng cung cp RSVP ( tc ch cung cp dch v theo kiu Best-

effort) s lm tc nghn lung. Do , bn nhn khi u vic ng k ti nguyn c th yu cu mt thng ip

xc nhn cho bit yu cu c c thit lp trong mng. Bn nhn c yu cu xc nhn trong bn tin RESV

v nhn c bn tin RESVconf nu nh vic ng k c thit lp thnh cng. Vic ng k ti nguyn

RSVP c duy tr rt ngn ti cc router v cc host nn vic ng k s b hy b nu RSVP khng gi li

thng ip xc nhn dc theo con ng ng k ti nguyn tn ti.

M rng RSVP-TE:

RSVP-TE m rng khi nim lung lu lng cho con ng chuyn mch nhn. Do cc router c

chc nng RSVP s gn lu lng thnh cc lung da vo nhn MPLS.

Sa i mt s lut cc thng ip ch ng v t trc ti nguyn c th truyn gia cc router

u vo v u ra ( m theo RSVP l gia ngun v ch cui cng).


Thm trng cho php bn tin tm ng t trc v nh x tr v cc gi tr nhn.

Cho php router u vo ch nh ra mt tuyn xc nh cho lung.

Thm mt s ty chn tng thm tnh linh hot. Router c th dng RSVP-TE ch phn phi nhn

thm ch khi khng c nhu cu v d phng ti nguyn.

Cc bn tin RSVP v m rng cho RSVP-TE:

nh dng tiu ca RSVP

Phin bn ( Version): 4bit, hin ti l phin bn 1

C ( Flags): 4 bit

Loi bn tin ( Message type): 8 bit

1. PATH

2. RESV

3. PATH Err

4. RESV Err

5. PATH Tear

6. RESV Tear

7. RESV Conf

Kim tra li ( Checksum): 16 bit, bn nhn kim tra xem bn tin nhn c c li hay khng.

Send TTL: 8 bit, c ngun gc t IP TTL. Nu IP TTL khng trng vi Send TTL th node trc khng

h tr RSVP.

D phng ( Reserved): 8 bit

Chiu di ( Length): 16 bit, hin th chiu di ca ton b gi tin RSVP, tnh bng byte.

nh dng RSVP Objects

Chiu di ( length): 16 bit, chiu di ca phn RSVP Object


Class Number: nh ngha mt Object class

C-type: Gi tr m c quy nh Class Number

Object Data: D liu c nh ngha b Class Number v C-type

Object Name Loi bn tin

RSVP M t

Adspec PATH Mang d liu qung b: tr, bng thng,

thng s iu khin t QoS

Detour PATH Used in one-to-one backup to identify detour

LSPs

Error

PATH Err

RESV Err

RESV Conf

Xc nh mt li trong bn tin PATH Err v

RESV Err hoc xc nhn trong bn tin RESV

Conf

Explicit Route PATH ng nh tuyn xc nh

Fast Reroute PATH c s dng to ng d phng cho LSP

chnh

Filter

RESV

RESV Tear

RESV Err

Xc nh ngun gc ca phin giao dch

Filter Spec RESV nh ngha mt nhm cc gi tin nhn c

yu cu v QoS

Flow Spec RESV nh ngha yu cu v QoS

Hello Hello C th l mt yu cu hay hi p

Hop PATH

RESV

Mang a ch IP ca node gi bn tin (

node c RSVP )v cng giao tip ng ra.

Integrity Tt c cc bn tin Mang d liu xc thc ngun gc v m

bo tnh ton vn ca bn tin RSVP

Label RESV Cha gi tr nhn

Label Request PATH Yu cu ng k nhn

Null C Class Number l 0, khng c C-type, ni

dung s c b qua ni nhn.

Policy data

PATH

RESV

PATH Err

RESV Err

Chnh sch vi d liu

Record Route PATH

RESV

Danh sch cc a ch Ip m bn tin PATH i

qua

RESV Conf RESV Hi p v xc nhn mt yu cu t ch


RESV Conf

Scope

RESV

RESV Err

RESV Tear

Mang mt danh sch cc node gi vi

thng tin trong bn tin c chuyn tip

Sender PATH a ch IP ca node gi v mt s thng tin

xc nh

Session Tt c cc bn tin Cha a ch IP ch, giao thc IP v s port,

xc nh mt phin lm vic c th

Session

Attribute PATH

Cha cc thng s v u tin, c, di

tn v tn phin.

Source Route PATH Cha cc a ch trong phn nh tuyn xc

nh ( ERO)

Style RESV H tr thng tin v vic t ch

Time PATH

RESV Thi gian cho vic lm mi bn tin

Tspec PATH nh ngha tnh cht ca lung lu lng

3.2.2. Giao thc CR-LDP

CR-LDP l giao thc m rng ca LDP c th xy dng mt LSP trn tuyn nh tuyn xc nh

(explicit route) v dnh sn ti nguyn trn ton tuyn.

xy dng LSP trn tuyn xc nh, CR-LDP a vo mt thnh phn mi, c gi l ER (Explicit route).

Cu trc cng nh cch thc x l thnh phn ny ti cc LSR hon ton tng t nh thnh phn Explicit

route ERO m ta cp trong phn RSVP m rng.

Qu trnh xy dng LSP, hay cn gi l qu trnh n nh nhn c thc hin di hnh thc xui dng theo

yu cu (downstream on demand) v s dng bn tin LDP Label Request. h tr chc nng nh tuyn xc

nh, bn tin ny c thm thnh phn ER.


Gi s LSR 1 mun xy dng LSP t LSR1 n LSR4 v i qua LSR2, LSR3 : LSR1 ->LSR2 ->LSR3 ->LSR4

v thc hin iu ny, LSR1 to ra thnh phn ER bao gm ba nt mng, cn c gi l abstract nodes :

LSR2, LSR3, LSR4. Mi nt mng c c trng bng a ch IPv4. Ch rng, mi a ch Ip nh th c th

l a ch ca mt giao din no trn LSR (trong trng hp ny, a ch IP gn lin vi mt giao din) hoc

l a ch ca ton b LSR. ng thi, LSR1 xy dng bn tin LDP Label Request v km theo thnh phn ER

ny. Sau khi c c bn tin hon chnh, LSR1 xc nhn LSR2 v nt mng u tin trong thnh phn ER nn

s gi bn tin ny n LSR2. Nhn c bn tin ny, LSR2 nhn bit c n l nt mng u tin cng nh l

nt mng tip theo l LSR3 trong thnh phn ER. LSR2 s hiu chnh li thng tin thnh phn ER bng cch

xa i thng tin lin quan n n v gi bn tin Label Request n LSR3 trn kt ni gia LSR2 v LSR3. Vo

thi im ny trong thnh phn ER ch cn hai nt mng l LSR3 v LSR4. Cch x l bn tin LDP Label

Request ( cng nh s iu chnh thnh phn ER) ti LSR3 hon ton tng t LSR2. Khi bn tin ny n

LSR4, LSR4 nhn ra rng n l nt mng cui cng trong thnh phn ER. V th, LSR4 to ra bn tin Label

Mapping v gi n LSR3. Bn tin ny bao gm thnh phn nhn v cc thnh phn khc. Khi nhn, LSR3 s

dng gi tr nhn trong bn tin n nh cho ng lin kt gia n v LSR4 dnh cho lu lng. Tip theo,

LSR3 gi bn tin Label Mapping n LSR2 v cng tng t, bn tin ny c cha thng tin nhn. Ti LSR2,

cch thc x l bn tin ny cng ging ti LSR3. Cui cng, khi LSR1 nhn c bn tin ny th qu trnh xy

dng LSP kt thc.

ng thi vi thng tin nhn, giao thc CR-LDP s thng bo cho cc LSR bit c yu cu ti nguyng

mng m lung lu lng cn c p ng. Thng tin ny c lu gi trong thnh phn thng s lu lng

(Traffic Parameter). C 7 thng s lu lng c nh ngha :

- Tc d liu nh PDR ( Peak data rate)

- Kch thc chm cc i PBS (Peak burst size)

- Tc d liu cc i CDR (Committes data rate)

- Kch thc chm tha thun CBS (Committed burst size)

- Kch thc chm vt ngng EBS (Excess burst size)

- Tn s (Frequency)

- Trng s (Weight)

Thng s PDR v PBS cho php xc nh tc ti a ca lung lu lng i trn LSP. Cn thng s CDR v

CBS xc nh tc trung bnh ca lung lu lng. Cc LSR trn LSP s s dng nhng thng s ny xc

nh ngun ti nguyn mng thch hp dnh cho LSP ca lung d liu.

3.2.3. Giao thc phn phi nhn rng buc nh tuyn CR-LDP

tng c bn l m rng giao thc LDP h tr cc con ng chuyn mch nhn rng buc CR

LSP bng cch nh ngha c ch v cc gi tr TLV b sung v da vo cc giao thc c sn tm ra tuyn

theo rng buc tha mn yu cu.

nh tuyn rng buc c thit lp nh mt hot ng u cui n u cui, t CR-LSR ng vo n CR-

LSR ng ra, LSR ng vo s thit lp tuyn rng buc cho tt c cc nt tc ng c th d tr ti nguyn

bng cch dng giao thc phn phi nhn. Thut ng rng buc m ch rng mt s iu kin phi c tha


mn cho cc lin kt ga cc nt nh yu cu bng thng ti thiu hoc yu t an ninh. Giao thc tm ra nhng

con ng nh vy ( nh OSPF c sa i ) b rng buc qung co v tm con ng trong min nh

tuyn tha mn cc rng buc ny.

Vi LDP, con ng chuyn mch nhn c thit lp ging nh l con ng ca chuyn tip IP bnh thng,

LDP ch thc hin vic phn phi nhn m thi. Vi CR-LDP, route ng vo c php chn ra hn mt con

ng hon chnh thay v ch chn ra chng k. Vn l CR-LDP khng gip router ng vo bit c con

ng no l con ng tt nht cho mt lung xc nh no . Mt trong nhng cc thc hin l thm mt s

m rng c bit cho cc giao thc nh tuyn hin ti nh OSPF hay IS-IS chng mang thm thng tin trng

thi mng nh mc s dng bng thng hin ti, bng thng cc i c sn, mc u tin tng i

Khi , cc bc thc hin nh sau :

1. Router ng vo tp hp thng tin trng thi mng

2. Mt lung yu cu ti nguyn t trc

3. Router ng vo tnh ton con ng cho lung ny

4. Router ng vo yu cu mt LSP r rng cho lung v nh x nhn cho con ng. y l chc nng

ca CR-LDP

5. Nu thnh cng, lung s s dng con ng chuyn mch nhn ny.

ch nh con ng chuyn mch nhn y , router ng vo phi a ra mt tuyn r rng

trong bn tin yu cu nhn. Mi hop dc theo LSP ny c th l nghim ngt hoc lng lo ( strict hay

loose). Nu l hop nghim ngt, n phi c chn l hop k tip ngay sau . Hop khng nghim ngt

linh hot hn do n c th l hop k trc tip hoc qua nhiu hop trung gian ri mi ti n. Hop

nghim ngt cho php con ng tht s c th c thay i sau ny. Nhng nu ta mun gi chnh

xc con ng nh lc u th ta phi gi yu cu c nh tuyn (route pinning) km theo.

Khi LSR xui dng tr v thng ip nh x nhn, n thc hin xong vic t trc ti nguyn v

ng hm LSP c thit lp.

Cc thng ip nh tuyn rng buc v TLV:

LDP dng TLV m ha cc thng tin c mang trong thng ip LDP. Nh trong hnh di y, LDP

TLV c m ha : 14 bit dng ch loi m, 2 bit U, F ch ra cch thc thc hin khi m LSR khng nhn ra

loi TLV ny, trong chiu di 2 byte, trng cha gi tr c chiu di thay i.

U F Loi Chiu di

Gi tr

Khi nhn mt TLV khng bit, nu bit U=0, mt thng bo s c gi v ni xut pht thng ip v

ton b thng ip b b mc. Nu U=1, TLV b b mc mt cch im lng v phn cn li ca thng ip c

x l nh khng c mt TLV khng bit . Cn btF ch c p dng khi bit U c thit lp v thng ip


cha TLV khng bit ny c chuyn tip i. Nu F=0, TLV khng c chuyn tip, F=1 th TLV khng

bit ny c chuyn tip. Mi th xut hin trong thng ip LDP c th c m ha nh mt TLV nhng

khng phi lc no cng vy do n tn km khng gian v nhiu khi khng cn thit, v d khng cn m ha

TLV nu chiu di ca gi tr l c nh v loi gi tr ny c bit.

Yu cu nhn (0x0401) Chiu di bn tin

ID bn tin

FEC TLV

LSPID TLV (CR-LDP, bt buc)

ER-TLV (CR-LDP, ty chn)

TLV thng s luuy lng (CR-LDP, ty chn)

TLV c nh tuyn (CR-LDP, ty chn)

TLV lp ti nguyn (CR-LDP, ty chn)

TLV quyn u tin (CR-LDP, ty chn)

nh x nhn (0x0400) Chiu di bn tin

ID bn tin

TLV lp chuyn tip tng ng

TLV nhn

ID ca bn tin yu cu nhn

TLV LSPID (CR-LDP, ty chn)

TLV lu lng (CR-LDP, ty chn)

Nu giao thc phn phi nhn c dng cho nh tuyn rng buc, tuyn rng buc s c m ha bng

mt chui cc chng ng r rng (explicit route hop) v c cha trong thng ip CR-LDP. Mi ER hop

c th xc nh mt nhm cc nt trong tuyn ng bt buc v cc gi tr TLV m t cc tham s lu lng

nh tc nh, tc c nh. Mt tuyn rng buc nh th ny s yu cu to ra con ng gm cc nt xc

nh ny v ng nh th t n xut hin trong TLV.

nh tuyn r rng (0x0800) Chiu di bn tin

ER-Hop t 1 n n

Kiu Hop ER (gi tr thay i) Chiu di

Ni dung

Tham s lu lng (0x0810) Chiu di bn tin = 24

C Tn s D tr Trng lng

Tc d liu nh (PDR)


Kch thc chm cc i (PBS)

Tc d liu tha thun (CDR)

Kch thc chm tha thun (CBS)

Kch thc chm vt ngng ( EBS)

CR-LDP cn h tr vic cng ch ti nguyn, cho php mt thng ip yu cu nhn mi chim ly 1 ti

nguyn ang c s dng b 1 LSP no nu yu cu mi ny c mc u tin cao hn con ng ny. Mi

yu cu nh x nhn c th cha c hai gi tr mc u tin khi to (cho lc thit lp LSP) v mc u tin

chim gi (khi con ng thit lp ri). Hin c 8 mc u tin, cao nht l 0, thp nht l 7 v mc u tin

khi to ca mt CR-LDP khng nn cao hn mc u tin chim gi.

TLV mc u tin Chiu di = 4

u tin kh to u tin chim d D tr


Chng IV CHUYN TIP LU LNG VO MPLS TE TUNNEL Sau khi to ra mt TE Tunnel, vn tip theo l lm sao chc chn rng n s c chuyn tip vo

trong ng hm. C 6 cch chuyn tip lu lng vo trong cc TE Tunnel, bao gm:

Static routing (nh tuyn tnh).

Policy-based routing (nh tuyn da trn nn cc chnh sch).

Autoroute annuonce (nh tuyn t ng da trn vic thng bo).

Forwarding adjacency (Ln cn chuyn tip).

Direct mapping of AToM trafc onto TE tunnels (Ghp trc tip lu lng ca AtoM trn cc TE Tunnel)

Class-based tunnel selection (la chn cc Class-based Tunnel)

4.1. Static routing (nh tuyn tnh)

y l phng php n gin v d thc hin nht chuyn tip lu lng vo cc TE Tunnel. N

c cu hnh thit lp mt TE_LSP t u n cui ca tuyn LSP . Ngi qun tr s ch nh c th cc

tuyn LSP no c s dng chuyn tip lu lng TE. Do , Static routing c u im l rt d thc hin

nhng c nhc im l khng linh hot khi trin khai trong mt mng li rng ln.

4.2. Policy-based routing (nh tuyn theo chnh sch)

Policy based routing (PBR) s dng cc chnh sch thit lp trn cc giao tip ng vo vn

chuyn data sang cc hop k cn c xc nh trc. Cc TE LSP s c xc nh d vo cc chnh sch

v TE Tunnel s c thit lp da trn cc chnh sch ny. Khi thc hin PBR c th nh tuyn lu lng

n mt TE Tunnel c th bng cch thit lp giao din m khng cn phi thay i bng nh tuyn.

4.3. Autoroute Announce (nh tuyn t ng bng cch thng bo)

Tunnel MPLS TE Autoroute announce l qu trnh iu khin thit lp cc giao dn ng hm trn cc MPLS TE tunnel u v cui cc router v vy LSR c th tm thy cc c ch IP ch, next hop v TE Tunnel nh l giao din ng ra trn bng nh tuyn. V c bn, Autoroute Announce lm thay i thut ton SPF v vy LSR c th tm thy cc a ch IP Prefix . Lc , headend-LSR c xem l c kt ni trc tip vi tailend-LSR qua mt TE-LSP, v vy lu lng i ti tailend-LSR v cc router pha sau tailend-LSR u s dng TE-LSP lm giao din ng ra.

4.4. Forwarding adjacency (Ln cn chuyn tip).

Phng thc ny cho php cc headend-LSR qung b cc TE-LSP nh l lin kt ca n. Nhng router

trong vng c th xt thm nhng TE-LSP ny nh l lin kt trong qu trnh tnh ton ng i. c th s

dng phng thc ln cn chuyn tip th cn phi thit lp 2 ng TE-LSP gia 2 LSR, mi ng tng

ng mt hng v trn 2 LSR phi kch hot chc nng ln cn chuyn tip. Mt u im ca phng php ny

l mt cp TE-LSP c xem nh l mt lin kt v c qung b trong min IGP, v mt router trong vng

khng chy MPLS TE cng c th thy lin kt ny v xem xt n trong qu trnh tnh ton ng. V d : Chuyn tip lu lng trn cc TE Tunnel


Vi c ch nh tuyn IP, lu lng chuyn tip T R1 sang R7 s chn tuyn ngn nht l R1, R2, R3,

R7. Nu thit lp mt ng TE-LSP gia R2-R3 v mt ng na gia R4-R6 th lu lng vn ch i trn

TE-LSP R2-R3 bt chp TE-LSP R4-R6 c tt hn. Bi v lung lu lng ch c chuyn tip vo TE-LSP

ti headend-LSR (R2 v R4) m cc router khc trong vng khng bit c s tn ti ca 2 TE-LSP ny v n

khng c qung b. Nn khi lung lu lng i t R1 sang R7, R1 s chuyn tip lu lng ti R2 v n tnh

ton c rng tuyn i ti u nht l i qua R2, ti R2 s chuyn tip lu lng ln TE-LSP R2-R3.

Khi s dng ln cn chuyn tip, cc TE-LSP R2-R3 v R4-R6 c qung b nh l lin kt ca 4

router R2, R3, R4, R6. Lin kt ny c qung b thng qua OSPF hoc IS-IS n router R1 v R7. R1 thm

hai lin kt tng ng vi hai TE-LSP ny vo qu trnh tnh ton ng CSPF.Lc ny TE-LSP no c chi

ph thp nht s c R1 chn truyn lu lng, nu chi ph bng nhau th R1 s thc hin cn bng ti trn

cc TE-LSP ny.

4.5. Direct mapping of AToM trafc onto TE tunnels (Ghp trc tip lu lng ca AtoM trn cc TE

Tunnel):

y l mt ng dng nng cao ca MPLS TE, cho php ng gi cc gi tin IPv4/IPv6, cc giao thc lp lin kt lp d liu ATM. Frame Relay, PPP, HDLC, Ethernet, . Vo bn tin MPLS. N ch cho php truyn theo phng thc im im, c cu hnh ti

Headend-LSR ch nh c th lu lng ca loi giao thc no s truyn trn TE-LSP no.

4.6. Class-based tunnel selection (la chn cc Class-based Tunnel)

Cho php truyn lu lng ca cc lp dch v (CoS) khc nhau trn nhng TE-LSP khc nhau ca

cng mt cp Headend-LSR v Tailend-LSR. Router s kim tra gi tr IP-Precedence trong trng ToS ca

header IP hoc gi tr EXP trong MPLS. Da trn gi tr ny, router s quyt nh TE-LSP ph hp cho lung

lu lng. Ta c 3 bit EXP tng ng vi 8 mc QoS, v vy ta c th nh x 8 mc Qos ny n 8 TE-LSP

khc nhau gia 1 cp LSRs.


Chng V TI NH TUYN NHANH

5.1. Fast ReRoute Ti nh tuyn nhanh

MPLS TE thng c trin khai trong mng li c dung lng lin kt rt ln. Nu mt lin kt hoc

mt router b s c, lu lng s c nh tuyn li i qua node s c . D vic nh tuyn li rt nhanh,

thm ch ch mt vi giy nhng n vn c th gy mt mt mt lng ln lu lng v dung lng ng

truyn rt cao. Vic gy nh hng rt nhiu n cc dch v, v d nh dch v VOIP.Mc d cc lin kt

c kh nng bo v ti lp 1-v d, vi mt c ch c gi l chuyn mch bo v t ng (APS), l cp

bo v tt nht ca MPLS . APS l mt c ch ni ting bo v kt ni quang. Mt bt li ca APS l mi

lin kt bo v gm mt lin kt d phng v mt card nhn ri.Nu c s c xy ra th lin kt quang hc bo

v ny chuyn sang lin kt d phng.

Vic bo v cc lin kt v node vi TE th hiu qu hn nhiu bi v n khng cn mt lin kt d phng

vt l. V vy, bo v lin kt v node khi s dng TE c chi ph r hn so vi phng php bo v ca tuyn

quang. Mt ng hm d phng s c to trc nn s khng mt thi gian bo hiu thnh lp tuyn khi

thit b gp s c. C 2 c ch thc hin vic bo v l: bo v lin kt v bo v node. Hai phng php ny

u cung cp c ch hi phc cc b v c mt im chung l: vic hi phc phi gn im b s c nht .

Nh vy, n c th x l tng i nhanh v nh tuyn li tuyn LSP t lin kt b s c sang ng d

phng trong khong thi gian ngn khong hng chc ms.

Khng ch lu lng c iu khin sang ng d phng khi gp s c m c bn tin bo hiu (RSVP) cng

c chuyn qua ng d phng ng TE nh tuyn li vn c bo hiu.

5.2. FRR- Bo v lin kt (Link Protection)

Bo v lin kt l bo mt lin kt c th c s dng cho TE-LSP. C ngha l tt c cc TE-LSP i qua

lin k c bo v bi mt ng d phng. Phng thc k thut ny cn gi l d phng linh hot

(facility backup) bi v tt c cc tuyn TE-LSP i lin kt u c d phng bng mt lin kt khc.

V d: Lin kt R1-R2 (protected link) c bo v bng ng d phng R1-R3-R2 (NHOP Backup

Tunnel). ng d phng ny ch bo v cc TE-LSP i qua lin kt theo chiu R1,R2, bo v theo chiu

R2,R1, cn cu hnh mt tuyn d phng khc t R2,R3,R1.

ng d phng hay cn gi l NHOP bypass backup tunnel lun lun bt u t im thay i ng

tunnel gi PLR .R1 chnh l PLR (Point of local repair). Lin kt d phng lun kt ni ti NHOP router ,

router ny l router cui ca lin kt.Router ny l im hp nht (R2 l MP)ca ng bo v v ng d

phng. ng d phng ny l mt tuyn tng minh c bo hiu bng RSVP, khi ng d phng c

to, RSVP s bo hiu nhng nhn s c s dng.Trong v d ny ch c 2 hop v chng ta c th m rng

nhiu hops nu cn.Khi ng d phng c to ra,RSVP bo hiu nhn nh bnh thng. Hnh di s cho

chng ta thy rng R2 bo hiu cho R3 bng nhn 3 v R3 bo hiu cho R1 bng nhn 16 cho ng d

phng.


Khi qu trnh bo v khng cn c s dng th cc gi tin c chuyn sang tunnel 1 lin kt gia R1

v R2 c biu din hnh di.


Cc gi tin trn LSP ca tunnel 1 chuyn n R1 vi nhn l 30 sau c hon i thnh nhn 33 khi

gi tin ri khi R1.Cui cng nhn 33 c chuyn thnh nhn 40 khi ra khi R2.Hnh di y s ch r khi

vn kt ni gp s c th gi tin chuyn t R1 sang R2 s b hy.Ngay khi lin kt gia R1 v R2 b hy th

PLR (R1) bt u gi lu lng t TE tunnel 1sang ng d phng NHOP qua R3.

Gi tin n R1 s c thay nhn 30 bng nhn 33 trc, sau R1 s chng thm nhn 16 n R3 ca

NHOP tunnel vo gi tin. Gi tin n R3 s c g nhn v chuyn ti R2 (MP). Ch rng nhn ca gi tin


ti R2 l ging nhau khi truyn qua lin kt R1-R2 hay i theo ng NHOP tunnel, ch khc l gi tin n R2

bng giao tip vo khc nhau. V Router s dng khng gian nhn chung cho cc giao tip nn router ch xt

cc gi tin n cng nhn ch khng quan tm n t giao tip no.

PLR ch nn s dng ng d phng cho cc TE-LSP mt cch tm thi. V khi lin kt b s c, mt

bn tin PathErr s c PLR gi v cho headend-LSR ca TE-LSP . Khi headend-LSR nhn c bn tin

PathErr n s tnh ton v thit lp li ng i mi. Lc thnh lp xong tuyn mi th ng TE-LSP c ang

c truyn trn ng d phng s khng cn c dng na.

Khi headend-LSR nhn c bn tin PathErr th n s ngt ng TE-LSP cho n khi TE-LSP c

c nh tuyn li. V vy cn kch hot chc nng FRR trnh xy ra trng hp ny. Lc bn tin

PathErr s gi thng tin chc nng phc hi cc b (Local Repair). Thng ny ny s bo cho headend-LSR

rng n khng nn ngt TE-LSP d phng Tunnel ny trong khi ang nh tuyn li v nu Tunnel ny b ngt

th s lm mt lu lng ca h thng.

IGP cng bo hiu l ng chnh b hng.Khi PLR s dng ng d phng nh tuyn ng bo

v LSP,PLR s gi bn tin PATH ca ng bo v i trn ng d phng hay khi ng d phng c s

dng.

Mt bt li khi s dng phng php bo v lin kt l NHOP tunnel bo v cho ton lin kt. Nh vy

tng bng thng qua lin kt ti mt thi im c th rt ln, m ng d phng khng thit lp dnh ring

bng thng cho trng hp ny, nn c th n s khng bng thng kh dng chuyn ton b lu lng

t lin kt b s c qua n v c th dn n mt gi. Nhng do vic s dng ng d phng ch l tm thi

headend-LSR nh tuyn li ng khc, nn FRR c th khng hon ton bo v c lung lu lng trn

lin kt b s c nhng cng c th chp nhn c trnh trng hp mt ton b lu lng.

Vic nh tuyn li ti headend-LSR c th khng tm c mt tuyn ph hp trong trng hp mt TE

tunnel ch i theo mt tuyn tng minh m khng c mt tuyn ng.Nu lin kt bo v b down th lin kt

d phng s c s dng ngay.Bi v headend khng th tnh ton 1 ng no khc i trong mng. gii

quyt vn ny th c th cu hnh mt tuyn ng vi ch s cao hn tuyn tng minh. Lc khi nh

tuyn li th headend-LSR s c c mt tuyn thay th khc.

ng d phng c cu hnh sn trn cc b router PLR.Chng ta c th ch nh ng d phng vi

giao din lnh mpls traffic-eng backup-path vo tuyn lin kt bo v. Chng ta c th cu hnh cc ng d

phng vi tuyn tng minh t PLR n router next-hop.Khi Router headend nm trn lin kt bo v, chng ta

s ch th tuyn ng no c s dng lm ng d phng (fast reroute) vi cu lnh tunnel mpls traffic-

eng fast-reoute. Lnh ny t c Session vi thuc tnh l 1 ch ra rng tunnel mun c bo v.

Thng thng chng ta khng nn s dng ng d phng. V ng d phng s khng thng bo vic t

ng vic nh tuyn hay thay i cu hnh. Bn cnh chng ta phi m bo cc lin kt bo v v cc lin

kt trong ng d phng khng chia s ti nguyn ging nhau.Chng ta c th cu hnh cc ng d phng

bng nh tuyn tnh. Tuy nhin, chng ta cng c th cu hnh n nh mt ng loi tr. y l mt tuyn

tng minh v ta c th loi tr mt hop (mt LSR). Vi ng d phng ta phi loi b cc lin kt bo v

khi nhng tuyn chnh.

5.3. FRR Bo V Node (Node Protection)

Vi nh tuyn nhanh trong bo v node th n c th bo v ton b lin kt ca node . Nguyn l

hot ng ca bo v Node kh ging vi bo v lin kt. N s to mt ng d phng chng k k tip


(NNHOP) kt ni t router PLR n router nm sau router c bo v. Khi chng ta cu hnh vi cu lnh

tunnel mpls traffic-eng fast-reoute node-protect trn headend ca tuyn th headend ny s bt ln c 0x10

nm trong bn tin PATH, ch th rng n mun bt Node bo v.

C 2 vn lm cho vic bo v node phc tp hn bo v lin kt. Ban u khi s dng ng hm d

phng, cc gi khng n NHOP LSR (berlin) na m n NNHOP LSR (Rome), v vy PLR phi hc li nhn

gi tin n NNHOP LSR (Rome) ging vi gi tin m (berlin) c trc . gii quyt vn ny , th

nhn n NNHOP LSR c gn trong trng subobject ca RRO object trong bn tin RESV gi t NNHOP

LSR n PLR. Khi s dng ng d phng, cc gi tin n PLR ny thi n s i nhn n bng nhn ca

ng d phng NNHOP.

Vn tip theo l ng d phng khng i qua node c bo v, mc d thng tin ERO trong bn tin

PATH vn gi a ch ca node . V vy ng d phng trnh i qua node c bo v th cn ch

nh router ID ca node cn loi b trong tuyn tng minh.

Ngoi ra PLR vn cn phi gi bn tin PATH n cc router thuc ng hm NNHOP duy tr hot

ng.

V d: Mt TE-LSP Tunnel1 i t router (paris) n router (Sydney) theo tuyn Paris, brussels, berlin, rome,

sydney. ng d phng NNHOP i t router (Brussels) (PLR) qua router (Frankfurt) ti router (rome) MP).

ng hm d phng s khng i qua router c bo v l router (berlin).


Cc gi tin c nhn 33 i t Paris, brussels, ti brussele s i nhn thnh 30 v chuyn tip ti router

(berlin), ti router (berlin) tip tc i nhn v chuyn tip ti router ti (Rome),sau n g nhn v chuyn

gi tin IP ti Router ti (sydney)

Khi Router ti (berlin) b s c th n s chuyn qua s dng ng d phng NNHOP.Cc gi tin t

Paris chuyn sang s c router ti (brussel) i nhn n NNHOP (Rome) l nhn 31 m nhn ny c c

bo hiu trong bn tin RESV. Sau router ti (brussel) s chng tip thm mt nhn 17 ti router ti

(frankfut). Ti router (frankfult) khi nhn cc gi tin t router(brussel) s g nhn v chuyn tip gi tin ti

router(rome). Nh vy gi tin ti router ti (rome) u mang nhn 31 trong c 2 trng hp trc v sau khi s

dng NNHOP backup tunnel

Documents

MPLS TE - Nhom Tienhung