Các Giao Thức Định Tuyến

ThS u Bu Long

1Mng my tnh nng cao-V1

RouterRouter Chuyn gi tin gia cc mng m n

kt ni n. Hot ng trn tng 3 ca m hnh

OSI.OSI. Cc router dng cc c ch khc

nhau xc nh ng i tt nhttrn mng.

Router c th lin kt cc loi mngkhc nhau.

2Mng my tnh nng cao-V1

Phn loi nh tuynPhn loi nh tuyn nh tuyn tnh

nh tuyn ng Distance Vector Link state

Mng my tnh nng cao-V1 3

DISTANCE VECTOR DISTANCE VECTOR ROUTINGROUTINGROUTINGROUTINGnh ngha khong cch bng s node trung gian

Vector khong cchVector khong cch Mi router khi mun gi gi tin n

router khc th cn c thng tin v ach mng v cng vt l tng ng.

Bn cnh cn c khong cch, Bn cnh cn c khong cch,c tnh l s router trn ng i.

Bng cc gi tr khong cch nyc trao i gia cc router khi cnthit.


Vector khong cchVector khong cch

R3N1

N5N4Destination Distance Port

N1 0 1*N2 1 2

R1

R2

R3N1

N2 N3

N2 2 3N3 1 2N3 2 3N4 1 3N4 2 2N5 1 3N5 2 2

1

2

3

Bng vector khong cchBng vector khong cch Bng nh tuyn c khi to ng

Router khi to bng da vo cc mng kt ni trc tip, khong cch bng 0

Cc router trao i bng nh tuyn vi nhau nh k. Nu router k (GS l R2) qung b ng nh

tuyn n mng N vi khong cch D, th ta c khong cch n N l D+1

Router nhn s cp nht li bng nh tuyn vi ng i n mng N l qua port ni vi router R2 vi khong cch D+1


Cp nht bng nh tuynCp nht bng nh tuyn


Distance Vector TablesDistance Vector Tables

N1

N4

Dest Distance RouteN1 0 1N2 0 2N3 0 3

1

N2

N3

R1 R2

N5Dest Distance RouteN4 0 1N5 0 2

T141

2

3

31

2T1 T1 T1


N1

N4

1

Dest Distance RouteN1 0 1N2 0 2N3 0 3

N4 0 1

N5 0 2

N1 1 3

N2 1 3

N3 1 3

N2

N3

R1 R2

N5

41

2

3

31

2T2T2T2T2


N1

N4

N1 0 1N2 0 2N3 0 3N4 1 4N5 1 4

1

N2

N3

R1 R2

N5

N4 0 1N5 0 2N1 1 3N2 1 3N3 1 3

N5 1 4

41

2

3

31

2

V d Distance VectorV d Distance Vector

Leamington 86

Essex 21

Welcome to Bobton

Population: 1Essex 21

Windsor 46

Whoohoo!

A friend!

RIPRIPRouting Information Protocol

Hot ng ca RIPHot ng ca RIP L mt loi nh tuyn da trn vector

khong cch Cc node trong mng c chia

thnh 2 loi: Active node: Active node: L routers, nhn qung b ca lng ging

xy dng bng nh tuyn. Qung b thng tin nh tuyn ca chnh mnh

Passive node: Thng l cc my tnh, ch nhn m khng

qung b i.


Hot ng ca RIPHot ng ca RIP C active v passive node u cp

nht bng nh tuyn ca mnh bng cc gi qung b t cc node khc

Cc mu tin ng i vi khong Cc mu tin ng i vi khong cch ngn hn s c cp nht Cc ng i cng khong cch khng c cp nht.


nh dng gi tin RIPnh dng gi tin RIP

command

version

1

1

octets

Cho bit gi tin hi hay tr li

reserved

address family ID

address

metric

1

2

2

14

4

Lp li ng vi tng mu tin

Gi hi & tr liGi hi & tr li Gi hi: c gi bi router khi thng

tin ht hn Gi tr li:

Gi tr li cho gi hi Gi tr li cho gi hi Gi nh k Gi khi c thay i v mng


V d: Vn vi DVV d: Vn vi DV

Xt m hnh mng nh bn di:

BA C1 1 12

BA C

Dest Dist PortB 1 1C 2 1

Dest Dist PortA 1 1C 1 2

Dest Dist PortA 2 1B 1 1

1 1 12

V d: Vn vi DVV d: Vn vi DV Khi link gia B v C b t? B s nhn ra trc tin v c tm ng

khc i n C

BA C



Dest Dist PortA 2 1B 1 1

1 1 12X

V d: Vn vi DVV d: Vn vi DV B s hi router ln cn (A) A s tr li???

A tra bng nh tuyn ca mnh tm ng n C

BA C


Dest Dist PortA 1 1C ? ?

1 1 12X

V d: Vn vi DVV d: Vn vi DV A c thng tin ng n C vi khong

cch l 2 ng ny i thng qua link b t, nhng A khng

bit. B s nhn thng tin (sai) rng c th n C

thng qua Athng qua A B cp nht ng i vi khong cch =3

BA C



1 1 12X

V d: Vn vi DVV d: Vn vi DV G/s B mun gi gi tin cho C:

B s gi sang A: Nh thng tin trong bng nh tuyn

A s gi li B... Dn n lp lin tc gi tin...

BA C



1 1 12X

V d: Vn vi DVV d: Vn vi DV Bn cnh , khi cc gi tin cp nht nh tuyn c gi, A v B c th lin tc cp nht khong cch sai n C tng dn.C tng dn.

Gii php: Count to infinity Split Horizon


Count to InfinityCount to Infinity V d ng i n host D

D R1 R2 NetworkR3

Count to InfinityCount to Infinity G/s link gia R1 v D fail?

R1 nhn bit v tm ng i khc

D R1 R2 NetworkR3X

Count to InfinityCount to Infinity R2 qung b ng n D (vi distance 2)

R1 khng bit l ng ny i qua chnh mnh D.

D R1 R2 NetworkR3?

Count to InfinityCount to Infinity R1 cp nht ng n D

Khong cch = 3 (2+1) ng i thng qua R2

D R1 R2 NetworkR3?

D 3

Count to InfinityCount to Infinity R2 cp nht ng i n D (theo thng tin

t R1) Khong cch s l 4 (3+1) Vector khong cch c gi cho R1

D R1 R2 NetworkR3?

D 4

Count to InfinityCount to Infinity R1 li cp nht thng tin n D

Khong cch 5 (4+1) ... V/v (n gi tr infinity)

D R1 R2 NetworkR3?

D 5

Count to InfinityCount to Infinity Khi n gi tr infinity, R2 xc nhn khng tm c ng n D qua R1

R2 tip tc dng R3 tm ng n D

D R1 R2 NetworkR3?

Thi gian hi tThi gian hi t Mt nhiu thi gian hi t do:

Cc router mt nhiu thi gian tm ng. Mt s router nhn bit t kt ni, s khc th khng

Trong RIP, khong cch 16 c xem l infinityinfinity Kch thc mng dng nh tuyn RIP b gii

hn.

C ch Split HorizonC ch Split Horizon hn ch m n v cng:

DV khng gi qung b n port nhn. V d:

R1 qung b cho R2 ng n D: (D,1) R2 nhn v to ra mu tin ca mnh: (D,2) R2 khng qung b mu tin ny li cho R1 R2 khng qung b mu tin ny li cho R1 Nhng s gi n cc port khc.

D R1 R2 NetworkR3?

C ch Split HorizonC ch Split Horizon Vn :

Ngun ca mu tin cp nht cng phi c lu li Tuy nhin, vn c th b count to infinity khi c nhiu

router.

Cc c ch khcCc c ch khc Hold down timer: Tng tnh n nh khi

mng ang hi t, Poison Reverse: Router vn gi mu tin

cho cc mng b t kt ni, nhng thay gi tr khong cch bng infinitygi tr khong cch bng infinity

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