49689847-Dinh-tuyen-rip.pdf

7/28/2019 49689847-Dinh-tuyen-rip.pdf

1/25

GIAO THC NH TUYN RIP

N MN

SERVER+

GV hng dn: - Quang Trung

SV thc hin : - Tn Vn Hoan

- Phm Th c

SV:


2/25


MC LC

SV:


3/25

GIAO THC NH TUYN RIPLi ni u

1.1. Gii thiu....................................................................................................3

1.2. nh ngha..................................................................................................4

1.3. Thut ton...................................................................................................5

II. Giao thc nh tuyn - RIP..............................................................6

2.1. nh tuyn theo vct khong cch............................................................6

2.1.1. c im.................................................................................................6

2.1.2. Vct khong cch..................................................................................7

2.1.3. Vn v cc phng php gii quyt lp vng.....................................8

2.2. Chi tit v giao thc nh tuyn RIP.........................................................15

2.2.1. RIP phin bn 1.....................................................................................15

2.2.1.1. c im.............................................................................................15

2.2.1.2. Cu trc bn tin..................................................................................16

2.2.1.3. Cc b nh thi.................................................................................17

2.2.1.4. Thit k RIPv1....................................................................................18

2.2.2. RIP phin bn 2.....................................................................................19

2.2.2.1. c im.............................................................................................19

2.2.2.2. Cu trc bn tin..................................................................................19

2.2.2.3. Cc b nh thi.................................................................................21

2.2.2.4. Thit k RIPv2....................................................................................21

2.2.3. So snh..................................................................................................21

III. ng dng........................................................................................22

3.1. Gii hn....................................................................................................22

3.2. Bo mt....................................................................................................24

3.3. ng dng..................................................................................................24

VI. Kt lun, nh gi v hng pht trin.......................................24

I. Tng qut1.1. Gii thiu

SV:


4/25

GIAO THC NH TUYN RIPNgy nay, mt lin mng c th ln n mc mt giao thc nh tuyn

khng th x l cng vic cp nht cc bng nh tuyn ca tt c cc b nh

tuyn. V l do ny, lin mng c chia thnh nhiu h thng t tr (AS-

Autonomous System). H thng t tr l mt nhm cc mng v b nh

tuyn c chung chnh sch qun tr. N i khi cn c gi l min nhtuyn (routing domain). Cc giao thc nh tuyn c s dng bn trong

mt AS c gi l giao thc nh tuyn ni min IGP (Interior Gateway

Protocol). thc hin nh tuyn gia cc AS vi nhau chng ta phi s

dng mt giao thc ring gi l giao thc nh tuyn ngoi min EGP

(Exterior Gateway Protocol). Routing Information Protocol (RIP) c thit

k nh l mt giao thc IGP dng cho cc AS c kch thc nh, khng s

dng cho h thng mng ln v phc tp.Hin nay c nhiu giao thc nh tuyn ang c s dng. Tuy nhin

trong phn ny ta ch trnh by v giao thc thng tin nh tuyn RIP

(Routing Information Protocol).

RIP xut hin sm nht vo thng 6 nm 1988v c vit bi C.

Hedrick trong Trng i hc Rutgers. c s dng rng ri nht v tr

thnh giao thc nh tuyn ph bin nht trong nh tuyn mng.

RIP chnh thc c nh ngha trong hai vn bn l: Request ForComments (RFC) 1058 v 1723. RFC 1058 (1988) l vn bn u tin m t

y nht v s thi hnh ca RIP, trong khi RFC 1723 (1994) ch l bn

cp nht cho bn RFC 1058.

1.2. nh ngha

RIP l mt giao thc nh tuyn min trong c s dng cho cc h thng t

tr. Giao thc thng tin nh tuyn thuc loi giao thc nh tuyn khong

cch vct, giao thc s dng gi tr o lng l s bc nhy (hop

count) trong ng i t ngun n ch. Mi bc i trong ng i t

ngun n ch c coi nh c gi tr l 1 hop count. Khi mt b nh tuyn

nhn c 1 bn tin cp nht nh tuyn cho cc gi tin th n s cng 1 vo

gi tr o lng ng thi cp nht vo bng nh tuyn.

RIP c hai phin bn:

SV:


5/25

GIAO THC NH TUYN RIP RIP phin bn 1 RIPv1 (RIP version 1): RIPv1 l giao thc nh tuyn

phn lp, khng c thng tin v mt n mng con v khng h tr nh tuyn

lin vng khng phn lp CIDR (Classless Interdomain Routing), chiu di

bin ca mt n mng con VLSM (Variable-length subnet mask). RIPv1 s

dng a ch qung b. RIPv1 c xc nh trong RFC 1058 "RoutingInformation Protocol" nm 1988.

RIP phin bn 2 RIPv1 (RIP version 2): RIPv2 l giao thc nh tuyn

khng phn lp, c thng tin v mt n mng con v h tr cho CIDR,

VLSM. RIPv2 s dng a ch a hng. RIPv2 c xc nh u tin trong

cc RFC sau: RFC1387 "RIP Version 2 Protocol Analysis" nm 1993,

RFC1388 "RIP Version 2 Carrying Additional Information" nm 1993 v

RFC1389 "RIP Version 2 MIB Extensions" nm 1993.

1.3. Thut ton

RIP s dng thut ton nh tuyn theo vct khong cch DVA (Distance

Vct Algorithms)

Thut ton Vct khong cch: L mt thut ton nh tuyn tng thch

nhm tnh ton con ng ngn nht gia cc cp nt trong mng, da trn

phng php tp trung c bit n nh l thut ton Bellman-Ford. Cc ntmng thc hin qu trnh trao i thng tin trn c s ca a ch ch, nt k

tip, v con ng ngn nht ti ch. M t hnh thc thut ton ny nh

sau:

Gi thit

r l nt ngun, d l nt ch

Cdr l gi thp nht t nt r ti ch d

Nrd l nt tip theo ca r trn ng ti d

crs l gi ca lin kt t r ti s

DVA gi thit gi ca tuyn lin kt c tnh cng gi v dng.

Tnh ton

Bng nh tuyn trong mi nt r c khi to nh sau:

Crr = 0;

s : s Nrd th Crs = ;

Crd(r, d, Nrd) l tp cc gi ca con ng i t nt r ti nt d qua nhiu

nht (s -2) nt trung gian.

SV:


6/25

GIAO THC NH TUYN RIP+) Bc s =1 : Crd(r, d, 1) = Csd(d,1)= csd , Nrd r

+) Bc s >1 : Crd(d, Nrd) = Min[Min[Crd(r, d, s )], Crd(r, d, s -1)] , d r

Mt khi node r nhn c thng tin vct khong cch ((d, Csd),) t

nt s, r s cp nht bng nh tuyn tt c cc ch ti d trong tp cha s.Nu ( Csd + crs < Crd hoc Nrd = s) th (Crd = Csd + crs v Nrd = s).

II. Giao thc nh tuyn - RIP

2.1. nh tuyn theo vct khong cch

2.1.1. c im

nh tuyn theo vct khong cch thc hin truyn bn sao ca bng nh

tuyn t b nh tuyn ny sang b nh tuyn khc theo nh k. Vic cpnht nh k gia cc b nh tuyn gip trao i thng tin khi cu trc mng

thay i.

B nh tuyn thu thp thng tin v khong cch n cc mng khc, t

n xy dng v bo tr mt c s d liu v thng tin nh tuyn trong

mng. Tuy nhin, hat ng theo thut ton vct khong cch nh vy th b

nh tuyn s khng bit c cu trc ca ton b h thng m ch bit c

cc b nh tuyn ln cn kt ni trc tip vi n.Khi s dng nh tuyn theo vct khong cch, bc u tin l b

nh tuyn phi xc nh cc b nh tuyn ln cn ca n. Cc mng kt ni

trc tip vo cng giao tip ca b nh tuyn s c khong cch l 0. Cn

ng i ti cc mng khng kt ni trc tip vo b nh tuyn th b nh

tuyn s chn ng no tt nht da trn cc thng tin m n nhn c t

cc b nh tuyn ln cn. V d nh hnh 1: b nh tuyn A nhn c

thng tin v cc mng khc t b nh tuyn B. Cc thng tin ny c t

trong bng nh tuyn vi vct khong cch c tnh ton li cho bit t

b nh tuyn A n mng ch th i theo hng no, khong cch bao

nhiu.

SV:


7/25

GIAO THC NH TUYN RIPBng nh tuyn

A

Bng nh tuyn

B

Bng nh tuyn

CW 0 W 0 W 0X 0 X 0 X 0Y 1 Y 1 Y 1

Z 2 Z 1 Z 2Hnh 1: Khong cch ca cc b nh tuyn n cc mng.

Bng nh tuyn c cp nht khi c cu trc mng c s thay i. Qu

trnh cp nht ny din ra tng bc mt t b nh tuyn ny sang b nh

tuyn khc. Khi cp nht, mi b nh tuyn gi i ton b bng nh tuyn

ca n cho cc b nh tuyn ln cn. Trong bng nh tuyn c thng tin v

ng i ti tng mng ch: tng chi ph cho ng i, a ch ca b nh

tuyn k tip.

2.1.2. Vct khong cch

Thut ton vct khong cch (hay cn gi thut ton Bellman Ford) yu

cu ca mi b nh tuyn gi mt phn hoc ton b bng nh tuyn cho

cc b nh tuyn ln cn kt ni trc tip vi n. Da vo thng tin cung cp

bi cc b nh tuyn ln cn, thut ton vct khong cch s la chn

ng i tt nht.S dng cc giao thc nh tuyn theo vct khong cch thng tn t

ti nguyn ca h thng nhng tc ng b gia cc b nh tuyn li

chm v cc thng s c s dng chn ng i c th khng ph hp

vi nhng h thng mng ln. Ch yu cc giao thc nh tuyn theo vect

khong cch ch xc nh ng i bng cc bc nhy v hng i n ch.

Theo thut ton ny, cc b nh tuyn s trao i bng nh tuyn vi nhau

theo nh k. Do vy loi nh tuyn ny n gin l mi b nh tuyn ch

trao i bng nh tuyn vi cc b nh tuyn ln cn ca mnh. Khi nhn

c bng nh tuyn t cc b nh tuyn ln cn, b nh tuyn s ly con

ng no n mng ch c chi ph thp nht ri cng thm khong cch

ca mnh vo thnh mt thng tin hon chnh v con ng n mng

ch vi hng i t chnh n n ch ri a vo bng nh tuyn, sau

b nh tuyn ly bng nh tuyn gi i cp nht tip cho cc b nh

tuyn k cn khc.

SV:


8/25


Hnh 2: Chuyn bng nh tuyn

2.1.3. Vn v cc phng php gii quyt lp vng

2.1.3.1. Vn lp vng

a. Khi nim

Khi mng ch b li m vn c gi tin chuyn ti. Nhng v mng ch b li

nn gi tin khng th chuyn ti ch ca n c do vy n s chuyn htmng ny n mng khc (do c nhng mng xa mng ch vn cha bit

mng ch b li nn n vn ngh l n vn c ng ti mng ch m gi tin

mun chuyn ti) c nh th v s khng dng li gi l lp vng. Hin

tng ny s khng dng cho n khi no c mt tin trnh khc ct t qu

trnh ny.

b. Qu trnh xy ra lp vngnh tuyn lp c th xy ra khi bng nh tuyn trn cc b nh tuyn cha

c cp nht hi t do qu trnh hi t chm (Trng thi hi t l tt c cc

b nh tuyn trong h thng mng u c thng tin nh tuyn v h thng

mng v chnh xc).

SV:


9/25


Hnh 3: Hin tng lp vng

Trc ht Mng 1 b li, tt c cc b nh tuyn trong h thng mng

u c thng tin ng v cu trc mng v bng nh tuyn l chnh xc. Khi

chng ta ni cc b nh tuyn hi t. Gi s rng: B nh tuyn C

chn ng n Mng 1 bng con ng qua b nh tuyn B v khong cch

ca con ng t b nh tuyn C n Mng 1 l 3 (hop).

Ngay khi Mng 1 b li, b nh tuyn E lin gi thng tin cp nht cho

b nh tuyn A. B nh tuyn A lp tc ngng vic nh tuyn v Mng 1.

Nhng b nh tuyn B, C, D vn tip tc vic ny v chng vn cha bit v

Mng 1 b li. Sau b nh tuyn A cp nht thng tin v Mng 1 cho b

nh tuyn B v D. B nh tuyn B, D lp tc ngng nh tuyn cc gi d

liu v Mng 1. Nhng n lc ny b nh tuyn C vn cha c cp nht

v Mng 1 nn n vn nh tuyn cc gi d liu v Mng 1 qua b nh

tuyn B.

n thi im cp nht nh k ca b nh tuyn C, trong thng tin cp

nht ca b nh tuyn C gi cho b nh tuyn D vn cha c thng tin v

ng n Mng 1 qua b nh tuyn B. Lc ny, b nh tuyn D thy rng

thng tin ny tt hn thng tin bo Mng 1 b li m n va nhn t b

nh tuyn A lc ny. Do b nh tuyn D cp nht li thng tin ny vo

bng nh tuyn m khng hay bit nh vy l sai. Lc ny, trn bng nh

tuyn, b nh tuyn D c ng ti Mng 1 l i qua b nh tuyn C. Sau

b nh tuyn D ly bng nh tuyn va mi cp nht xong gi cho b

SV:


10/25

GIAO THC NH TUYN RIPnh tuyn A. Tng t, b nh tuyn A cng cp nht li ng n Mng

1 lc ny l qua b nh tuyn D ri gi cho b nh tuyn B v E. Qu trnh

c tip tc xy ra b nh tuyn B v E . Khi , bt k gi d liu no gi

ti Mng 1 u ti b gi lp vng t b nh tuyn C ti b nh tuyn B ti

b nh tuyn A ti b nh tuyn D ri ti b nh tuyn C.

2.1.3.2. Cc phng php gii quyt lp vng

Lp vng c th gii quyt bng cc phng php sau: nh ngha gi tr ti

a, ng ct ngang, ngn nga, cp nht tc thi, thi gian gi chm.

Sau y ta i chi tit vo tng phng php:

a. Trnh nh tuyn vng lp bng nh ngha gi tr ti a

Vic cp nht sai v Mng 1 nh trn s b lp vng nh vy hoi cho n khino c mt tin trnh khc ct t qu trnh ny. Tnh trng nh vy gi l

m v hn, gi d liu s b lp vng trn mng trong khi thc t Mng 1

b ngt.

Vi khong cch vct s dng thng s l s lng hop th mi b nh

tuyn chuyn thng tin cp nht cho b nh tuyn khc, ch s hop s tng

ln 1. Nu khng c bin php khc phc tnh trng m v hn, th c nh

vy ch s hop s tng ln n v hn.Bn thn thut ton theo nh tuyn theo vct khong cch c th t sa

li c nhng qu trnh lp vng ny c th ko di n khi no m n v

hn. Do trnh trnh trng li ny, giao thc nh tuyn theo vct khong

cch nh ngha gi tr ti a.

Bng cch ny, giao thc nh tuyn cho php vng lp ko di n khi

thng s nh tuyn vt qua gi tr ti a. V d nh hnh 4 di, khi thng

s nh tuyn l 16 hop ln hn gi tr ti a l 15 hop th thng tin cp nht

s b b nh tuyn hy b. Trong bt k trng hp no, khi gi tr ca

thng s nh tuyn vt qua gi tr ti a th xem nh mng khng th

m c.

SV:


11/25


Hnh 4: Trnh vng lp bng nh ngha gi tr ti a

b. Trnh nh tuyn vng lp bng ng ct ngang

Mt nguyn nhn khc gy ra lp vng l b nh tuyn gi li thng tin nhtuyn m n va nhn c cho chnh b nh tuyn gi nhng thng tin

. Sau y l cc bc gy ra lp vng:

B nh tuyn A gi mt thng tin cp nht cho b nh tuyn B v D

thng bo l Mng 1 b ngt. Tuy nhin b nh tuyn C vn gi cp nht

cho b nh tuyn B l b nh tuyn C c ng n Mng 1 thng qua b

nh tuyn D.

Khi b nh tuyn B ngh l b nh tuyn C vn cn ng nMng 1 mc d con ng ny c thng s nh tuyn khng tt bng con

ng c ca b nh tuyn B lc trc. Sau b nh tuyn B cng cp

nht cho b nh tuyn A l c ng mi n Mng 1.

Khi b nh tuyn A s cp nht li l n c th gi d liu n Mng

1 thng qua b nh tuyn B. B nh tuyn B nh tuyn n Mng 1 thng

qua b nh tuyn C. B nh tuyn C nh tuyn n Mng 1 thng qua b

nh tuyn D. Kt qu l bt k gi d liu no n Mng 1 u ri vo vnglp ny.

SV:


12/25

GIAO THC NH TUYN RIPC ch ng ct ngang s trnh c tnh hung ny bng cch: Nu b

nh tuyn B hoc D nhn c thng tin cp nht Mng 1 t b nh tuyn A

th chng khng gi thng tin cp nht v Mng 1 cho b nh tuyn A na.

Nh , c ch ng ct ngang lm gim c cp nht thng tin sai v

gim bt vic x l thng tin cp nht.

Hnh 5: Trnh lp vng bng c ch ng ct ngang

c. Trnh nh tuyn vng lp bng vic ngn nga (route poisoning).Route poisoning c s dng trnh xy ra cc lp vng ln v gip cho

b nh tuyn thng bo thng l mng khng truy cp c na bng cch

t gi tr cho thng s nh tuyn (chng hn l s lng hop) ln hn gi tr

ti a.

V d nh hnh 6 di: Khi Mng 5 b ngt th trn bng nh tuyn b

nh tuyn E gi tr hop ng n Mng 5 l 16, gi tr ny c ngha l Mng

5 khng truy cp c na. Sau b nh tuyn E cp nht cho b nh

tuyn C bng nh tuyn ny, trong ng n Mng 5 c thng s hop l

16 c gi l route poisoning. Sau khi b nh tuyn C nhn c cp nht

th b nh tuyn C s gi tr li thng tin ny cho b nh tuyn E. Lc ny

ta gi thng tin cp nht v Mng 5 t b nh tuyn C v b nh tuyn E l

poison reverse. B nh tuyn C lm nh vy tc l n gi thng tin route

poisoning ra tt c cc ng m n c.

Tm li, route poisoning c ngha l khi c mt con ng no b

ngt th b nh tuyn s thng bo v con ng vi thng s nh tuyn

ln hn gi tr ti a. C ch route poisoning khng h gy mu thun vi c

SV:


13/25

GIAO THC NH TUYN RIPch ng ct ngang. C ch ng ct ngang c ngha l khi b nh tuyn

gi thng tin cp nht ra mt ng lin kt th b nh tuyn khng gi li

nhng thng tin no m n va nhn t ng lin kt . By gi, b nh

tuyn vn gi li nhng thng tin nhng vi thng s nh tuyn ln hn

gi tr ti a. Th kt qu vn nh vy (tc l tt c nhng thng tin m gi vmng b li s b huy b). C ch ny gi l ng ct ngang kt hp vi

poison reverse.

Khi Mng 5 b ngt, b nh tuyn E s dng route poisoning bng cch t

gi tr 16 ln bng nh tuyn cho bit Mng 5 ny khng n c na.

Hnh 6: Trnh vng lp bng route poisoning

d. Trnh nh tuyn vng lp bng cp nht tc thi

Hot ng cp nht bng nh tuyn gia cc b nh tuyn ln cn c thc

hin theo chu k. V d: c sau 30 giy RIP thc hin cp nht mt ln. Ngoi

ra cn c c ch cp nht tc thi thng bo v mt thay i no trong

bng nh tuyn. Khi b nh tuyn pht hin ra c mt thay i no trong

cu trc mng th n lp tc gi bn tin cp nht cho cc b nh tuyn ln

cn thng bo v s thay i . Nht l khi c mt ng no b li

khng truy cp c na th b nh tuyn phi cp nht tc thi thay v i

n ht chu k. C ch cp nht tc thi kt hp vi route poisoning s m

bo cho tt c cc b nh tuyn nhn c thng tin khi c mt ng no

b ngt trc khi thi gian gi chm kt thc.

C ch cp nht tc thi cho ton b mng khi c thay i trong cu

trc mng gip cho cc b nh tuyn c cp nht kp thi v khi ng

thi gian gi chm nhanh hn.

V d nh hnh 7 di: B nh tuyn C cp nht tc thi ngay khi

SV:


14/25

GIAO THC NH TUYN RIPmng 10.4.0.0 khng truy cp c na. Khi nhn c thng tin ny, b

nh tuyn B cng pht thng bo v mng 10.4.0.0 ra cng S0/1. n lt b

nh tuyn A cng s pht thng bo ra cng fa0/0.

Mng 10.4.0.0 b li khng truy cp c

Vi c ch cp nht tc thi, b nh tuyn s gi bn tin ngay thng bo

s thay i trong bng nh tuyn ca mnh.

Hnh 7: Cp nht tc thi cho b nh tuyn ln cn

e. Trnh nh tuyn vng lp bng thi gian gi chm

Tnh trng lp vng n v hn c th trnh c bng s dng thi gian gi

chm nh sau:

Khi b nh tuyn nhn c t b nh tuyn ln cn mt thng tincho ta bit l mt mng X no khng truy cp c th b nh tuyn s

nh du vo con ng ti mng X l khng truy cp c v khi ng

thi gian gi chm. Trong khong thi gian gi chm ny, nu b nh tuyn

nhn c thng tin cp nht t chnh b nh tuyn ln cn lc ny thng bo

l mng X truy cp li c th b nh tuyn mi cp nht thng tin v

kt thc thi gian gi chm.

Trong sut thi gian gi chm, nu b nh tuyn nhn c thng tincp nht t mt b nh tuyn ln cn khc (khng phi l b nh tuyn ln

cn pht thng bo tin cp nht v mng X lc ny) nhng thng tin ny

cho bit c ng n mng X vi thng s nh tuyn tt hn con ng m

b nh tuyn c trc th n s cp nht thng tin ny v kt thc thi

gian gi chm.

SV:


15/25


Hnh 8: Thi gian gi chm mi b nh tuyn

Trong sut thi gian gi chm, nu b nh tuyn nhn c thng tin

cp nht t mt b nh tuyn ln cn khc (khng phi l b nh tuyn ln

cn pht thng bo tin cp nht v mng X lc ny) nhng thng tin nycho bit c ng ti mng X vi thng s nh tuyn khng tt bng con

ng m b nh tuyn c trc th n s b qua thng tin ny. C ch

ny gip cho b nh tuyn trnh c vic cp nht nhm nhng thng tin c

do cc b nh tuyn ln cn cha bit v mng X khng truy cp c.

Khong thi gian gi chm bo m cho tt c cc b nh tuyn trong h

thng mng c cp nht xong v thng tin mi. Sau khi thi gian gi

chm ht thi hn, tt c cc b nh tuyn trong h thng u c cpnht l mng X khng truy cp c, khi cc b nh tuyn u c nhn

bit chnh xc v cu trc mng. Do , sau khi thi gian gi chm kt thc

th cc b nh tuyn cp nht thng tin nh bnh thng.

2.2. Chi tit v giao thc nh tuyn RIP

2.2.1. RIP phin bn 1

2.2.1.1. c im

SV:


16/25

GIAO THC NH TUYN RIPRIPv1 l mt giao thc nh tuyn theo vct khong cch nn n qung

b (theo a ch 255.255.255.255) ton b bng nh tuyn ca n cho cc b

nh tuyn ln cn theo nh k. Chu k cp nht ca RIP l 30 giy. Thng

s nh tuyn ca RIP l s lng hop, gi tr ti a l 15 hop nu ln hn th

gi d liu s b hy b. Thi gian gi chm cho mt tuyn l 180 giy,nu ln hn th tuyn ny coi nh l ht hn.

RIPv1 l gio thc nh tuyn c s dng ph bin v mi b nh

tuyn IP u c h tr giao thc ny. RIPv1 c ph bin v tnh n gin

v tnh tng thch ton cu ca n. RIPv1 c th chia ti ra ti a l 6 ng

c chi ph bng nhau (mc nh l 4 ng).

RIPv1 l giao thc nh tuyn theo lp a ch. Khi RIP b nh tuyn

nhn thng tin v mt mng no t mt cng, trong thng tin nh tuynny khng c thng tin v mt n mng con i km. Do b nh tuyn s

ly mt n mng con ca cng p dng cho a ch mng m n nhn c

t cng ny. Nu mt n mng con ny khng ph hp th n s ly mt n

mng con mc nh theo a ch p dng cho a ch mng m n nhn c:

- a ch lp A c mt n mng con mc nh l 255.0.0.0

- a ch lp B c mt n mng con mc nh l 255.255.0.0

- a ch lp C c mt n mng con mc nh l 255.255.255.0Do RIPv1 l mt giao thc nh tuyn theo vct khong cch nn n s

dng c ch ng ct ngang chng lp vng.

2.2.1.2. Cu trc bn tin

Cc trng chc nng trong gi tin IP RIP:

SV:


17/25

GIAO THC NH TUYN RIP Command: Cho ta bit gi tin l gi tin yu cu (Request) hay gi tin

tr li (Response). Gi tin Request s a ra yu cu cho mt bng nh tuyn

gi tt c hay 1 phn bng nh tuyn ca n. Gi tin Response c a ra

khi 1 b nh tuyn nhn c gi tin Request. Nhiu gi tin RIP c th c

s dng vn chuyn cho mt bng nh tuyn ln. Version number: Ch ra phin bn RIP ang s dng. Trng ny dng

cc k hiu khc nhau ch ra cc phin bn khc nhau ang c s dng

trong mng.

Zero: Trng ny thc t khng s dng, n c thm vo cung

cp tnh tng thch v sau cho cc chun ca RIP. Trng ny c th c

thit lp mc nh gi tr 0.

Address-family identifier (AFI): Ch ra kiu a ch c s dng cu hnh mng. Do RIP c thit k mang thng tin nh tuyn cho nhiu

cc giao thc khc nhau nn mi loi s c 1 nhn dng ring cho ta bit kiu

a ch m giao thc ang s dng. Gi tr AFI cho IP l 2.

Address: Ch ra a ch IP ca cc b nh tuyn.

Metric: Cho ta bit c bao nhiu bc lin mng (internetwork hop)

i qua trong hnh trnh n ch. Gi tr ny s nm trong khong 1 n 15

cho cc ng i cn hiu lc v 16 cho cc ng i khng th thc hinc bi RIP.

2.2.1.3. Cc b nh thi

Nhng b nh thi ca RIPv1. h tr cho hot ng ca h thng,

RIP s dng 3 b nh thi bao gm: B nh thi nh k (periodic) iu

khin vic gi thng bo, b nh thi ht hn (expiration) qun l tnh hp l

ca mt tuyn v b nh thi thu lm rc (garbage collection) qung b li

ca mt tuyn:

B nh thi nh k: B nh thi ny iu khin vic qung b u

n cc thng bo cp nht. Mc d giao thc ch r mi b nh thi ny

phi c t l 30 giy, nhng cc m hnh ang hot ng hin nay thng

s dng mt s ngu nhin trong khong t 25 n 35 giy vi mc ch

trnh tnh trng qu ti trn mt lin kt mng khi tt c cc b nh tuyn gi

cp nht cng lc. B nh thi ny c m li. Khi t n gi tr 0, thng

bo cp nht s c gi v b nh thi li c thit lp li.

SV:


18/25

GIAO THC NH TUYN RIP B nh thi ht hn: B nh thi ny qun l tnh hp l ca mt

tuyn. Khi b nh tuyn nhn c thng tin cp nht v mt tuyn, b nh

thi ht hn cho tuyn ny s c thit lp l 180 giy. Mi ln c mt cp

nht mi v tuyn ny b nh thi c t li. Trong trng hp bnh

thng th c 30 giy iu ny xy ra mt ln. Tuy nhin nu c trc trc trnlin mng v b nh tuyn khng nhn c cp nht v tuyn ny trong

khong thi gian 180 giy, tuyn ny c xem nh l ht hn v gi tr

trng bc nhy ca n c t l 16, ngha l khng th n ch. Mi

tuyn u c b nh thi ht hn ca ring mnh.

B nh thi thu lm rc: Khi mt tuyn ht hn, b nh tuyn khng

loi b ngay tuyn ny ra khi bng nh tuyn. Thay vo , n tip tc

qung b tuyn ny vi gi tr o lng l 16. Cng lc , b nh thi thulm rc c t l 120 giy cho tuyn ny. Khi gi tr ca b nh thi ny

t ti 0, tuyn b loi khi bng nh tuyn. B nh thi ny cho php cc

ln cn bit v s khng hp l ca mt tuyn trc khi loi tuyn ra khi

bng nh tuyn.

2.2.1.4. Thit k RIPv1

Mt s iu cn nh trong thit k mng vi RIPv1 l n khng h tr VLSMhoc CIDR. Lc a ch IP vi RIPv1 yu cu mt n mng con ging

nhau cho mi thc th mng IP, 1 mng IP bng phng. Gii hn s hop trong

RIPv1 l 15. V vy kch thc mng khng th vut qu s gii hn .

RIPv1 cng qung b bng nh tuyn ca n 30 giy mt ln. RIPv1 thng

c gii hn khi truy nhp vo mng ni m giao thc ny c th hot ng

lin kt vi cc my ch c thc hin nh tuyn.

Nh trong hnh 9, khi s dng RIPv1, tt c cc a ch trong mng phi

c cng mt n mng con.

Hnh 9: Cc a ch phi c cng mt n mng con.

SV:


19/25


2.2.2. RIP phin bn 2

2.2.2.1. c im

RIPv2 l bn c pht trin t RIPv1 nn n c cc c im nh

RIPv1:- L mt giao thc nh tuyn theo vct khong cch, s dng s

lng hop lm thng s nh tuyn.

- Gi tr hop ti a l 15.

- Thi gian gi chm cng l 180 giy.

- S dng c ch chia r tng chng lp vng.

RIPv2 khc phc c nhng im gii hn ca RIPv1.

- RIPv2 c gi mt n mng con i km vi cc da ch mng trongthng tin nh tuyn. Nh m RIPv2 c th h tr VLSM v CIDR.

- RIPv2 c h tr vic xc minh thng tin nh tuyn.

- RIPv2 gi thng tin nh tuyn theo a ch a hng 244.0.0.9.

2.2.2.2. Cu trc bn tin

Bn tin IP RIPv2 cho php mang nhiu thng tin hn ngoi cc thng tin nh

trong bn tin IP RIP n cn cung cp mt c ch xc thc khng c h trbi RIP.

Mt s c tnh sau y l nhng du hiu ln nht c b sung vo RIPv2:

- S nhn thc ca dng tin truyn dn.

- H tr mt n con.

- a ch IP bc k tip.

- Bn tin a phng RIP-2.

Mt s h tr khc gm c s gia tng khi thng tin qun l v h tr chocc th ca b nh tuyn ngoi mng.

SV:


20/25

GIAO THC NH TUYN RIPCc trng chc nng trong nh dng bn tin IP RIPv2:

Command, Version number, AFI, Address, Metric: Chc nng ca

chung cng ging nh trong bn tin IP RIP.

Unused: C gi tr c thit lp mc nh l 0.

Route tag (Nhn ng i): Cung cp mt phng thc phn bit giab nh tuyn ni b (s dng giao thc RIP) v cc b nh tuyn ngoi (s

dng cc giao thc nh tuyn khc).

Subnet mask: Cha ng mt n mng con cho cc b nh tuyn.

Next hop: Cho bit a ch IP ca bc i tip m gi tin c th chuyn

tip.

Trong RIP phin bn 2, kiu bn tin xc thc c thm vo bo v

bn tin thng bo. Tuy nhin, khng cn thm cc trng mi vo thng bo.Mc u tin ca thng bo s cha thng tin xc thc. ch r mt mc

cha thng bo xc thc ch khng phi l thng tin nh tuyn, gi tr hexa

FFFF c t trong trng AFI. Trng tip theo trong thng bo xc thc

l loi xc thc, dng nh ngha phng php s dng xc thc.

Trng cui cng trong thng bo xc thc l cha d liu xc thc. nh

dng ca bn tin xc thc nh sau:

1-octetcommand

field

1-octetversion

number

field

2-octetunused

field

2-octetAFI

field

2-octetAuthentication

type

field

16-octetData

field

Hnh 10: Thng tin xc thc c thm trng AFI

Ngoi ra RIP phin bn 2 cn h tr pht a hng (Multicast) so vi phin

bn 1. RIP phin bn 1 s dng pht qung b gi cc thng bo RIP ti

tt c cc b nh tuyn ln cn. Do , khng ch cc b nh tuyn trn

mng nhn c thng bo m mi trm trong mng u c th nhn c.

Trong khi , RIP phin bn 2 s dng a ch a hng 224.0.0.9 pht a

hng cc thng bo RIP ti ch cc b nh tuyn s dng giao thc RIP trnmt mng m thi.

SV:


21/25


2.2.2.3. Cc b nh thi

Nhng b nh thi ca RIPv2 cng ging nh RIPv1. h tr cho hot

ng ca h thng, RIP s dng 3 b nh thi bao gm: B nh thi nh k

(periodic) iu khin vic gi thng bo, b nh thi ht hn (expiration)qun l tnh hp l ca mt tuyn v b nh thi thu lm rc (garbage

collection) qung b li ca mt tuyn

2.2.2.4. Thit k RIPv2

Mt s iu cn ghi nh trong vic thit k mng vi RIPv2 l n h tr

VLSM bn trong mng v CIDR tm tt nhng mng gn k bn kia.

RIPv2 cho php tm tt cc l trnh trong cng 1 mng. RIPv2 vn c giihn s hop l 16. V th kch thc mng khng th vt qu gii hn ny.

RIPv2 gi bng nh tuyn 30s mi ln n cc my gi a ch IP l

224.0.0.9. RIPv2 thng c gii hn khi truy nhp vo mng ni m giao

thc ny c th hot ng lin kt vi cc my ch c thc hin nh tuyn.

RIPv2 cng cung cp s xc nhn l trnh.

Nh trong hnh 11, khi s dng RIPv2, tt c cc i ch trong mng c

th c nhng mt n mng con khc nhau.

Hnh 11: Cc a ch c th c mt n mng con khc nhau.

2.2.3. So snh

a. Nhng im ging nhau:

L giao thc nh tuyn theo vct khong cch.

S dng s hop lm thng s nh tuyn. Chu k cp nht mc nh l 30 giy.

SV:


22/25

GIAO THC NH TUYN RIP S dng thi gian gi chm chng lp vng, thi gian ny mc nh

l 80 giy.

S dng c ch ct ngang chng lp vng.

Nu gi d liu n mng ch c s lng hop ln hn 15 th gi d

liu s b hy b. Cng gi nhng thng tin sau v mi ch :

- IP address: a ch ca my ch hoc mng

- Gateway: Cng vo ra u tin m ng dn tin v ch

- Interface: Phn mng vt l m s dng n cng ra u tin

ca ng dn v ch

- Metric : L s cho bit s hop n ch.

- Timer: L lng thi gian k t khi b nh tuyn cp nht lncui cng.

b. Nhng im khc nhau:

Bng so snh nhng im khc nhau gia RIPv1 v RIPv2:

RIP version 1 RIPv1 RIP version 2 RIPv2

nh tuyn theo lp a ch. nh tuyn khng theo lp a ch.Khng gi thng tin v mt n mng

con trong thng tin nh tuyn.

C gi thng tin v mt n mng

con trong thng tin nh tuyn.

Khng h tr VLSM. Do tt c

cc mng trong h thng RIPv1 phi

c cng mt n mng con.

C h tr VLSM. Do vy cc mng

trong h thng RIPv2 c th c

chiu di mt n mng con khc

nhau.Khng h tr CIDR C h tr CIDR.Khng c c ch xc minh thng tin

nh tuyn.

C c ch xc minh thng tin nh

tuyn.

Gi qung b thng tin nh tuyn

theo a ch : 255.255.255.255

Gi thng tin nh tuyn theo aa hng 224.0.0.9 nn hiu qu

hn.Cng gi nhng thng tin ging nhau v ch nhng RIPv1 khng gi

c thng tin v mt n mng con cn RIPv2 gi c thng tin v mt

n mng con.

III. ng dng

3.1. Gii hn

3.1.1. Gii hn chung cho c 2 RIPv1 v RIPv2:

SV:


23/25

GIAO THC NH TUYN RIP Mt iu bt li ca cc b nh tuyn khi dng RIP l chng kt ni

lin tc vi cc b nh tuyn ln cn cp nht cc bng nh tuyn ca

chng, do to ra mt lng ti ln trn mng.

c tnh ca RIP l cc gi gii hn di 15 hop v bng nh tuyn

c trao i vi cc b nh tuyn khc khong 30giy/ln. Nu mt b nhtuyn khng thng bo trong vng 180 giy, ng i qua b nh tuyn ny

c xem nh khng dng c. Cc vn c th xy ra trong lc to li

bng nh tuyn nu b nh tuyn ny c kt ni vi mt mng din rng

chy chm. Hn na, trao i cc bng lm mng thng xuyn qu ti, gy

tc nghn v cc tr hon khc.

Do RIP l giao thc nh tuyn theo vct khong cch nn mi b

nh tuyn nhn c bng nh tuyn ca nhng b nh tuyn ln cn ktni trc tip vi n do vy b nh tuyn s khng bit c chnh xc cu

trc ca ton b h thng mng.

RIP s dng thut ton nh tuyn theo vct khong cch. Nu c

nhiu ng n cng mt lc ti ch th RIP s chn ng c s hop t

nht. Chnh v vy da vo s lng hop chn ng nn i khi cn

ng m RIP chn khng phi l ng ngn nht v nhanh nht ti ch.

Khng dng cho nhng mng ln hay phc tp.3.1.2. Nhng gii hn ringca RIPv1 v RIPv2

a. Nhng gii hn ca RIPv1:

Khng gi thng tin mt n mng con trong thng tin nh tuyn.

Khng h tr xc minh thng tin nhn c.

Gi qung b thng tin nh tuyn theo a ch 255.255.255.255 nn n

s gi ti tt c cc b nh tuyn ln cn (tc l khng ch c b nh tuyn

trn mng nhn c m mi trm trong mng c th nhn c).

Khng h tr VLSM (Variable Length Sunbet Masking - Subnet Mask

c chiu di khc nhau) v CIDR(Classless Interdomain Routing - Tuyn lin

vng khng phn lp).

b. Sang n phin bn 2 th RIPv2 gii quyt cc gii hn ca RIPv1:

C gi thng tin mt n mng con i km vi cc a ch mng trong

thng tin nh tuyn.

C h tr vic xc minh thng tin nh tuyn.

S dng a ch a hng 224.0.0.9 pht a hng cc thng bo

RIP ti ch cc b nh tuyn s dng giao thc RIP trn mt mng.

SV:


24/25

GIAO THC NH TUYN RIP Nh c gi thng tin mt n mng con trn nn RIPv2 c th h tr

VLSM v CIDR.

3.2. Bo mt

Do c th khai thc nhng im yu trong bo mt ca RIP, do vy chng ta xut mt cch bo v mi giao thc nh tuyn theo khong cch vct

mang tn l S-RIP (A Secure Distance Vector Routing Protocol).

Nhng mc tiu ca S-RIP bao gm:

1. Ngn chn nhng b nh tuyn gi mo.

2. Ngn chn s gi mo quyn hn.

3. Ngn chn gian ln khong cch (c ngn v di). S gian ln c th

thc hin bi nhng nt ring l hoc nhng nt b gi mo.

3.3. ng dng

RIP c thit k nh l mt giao thc IGP (Interior Gateway Protocol l

giao thc nh tuyn ni min) dng cho cc h thng t tr AS (AS

Autonomouns system) c kch thc nh, RIP ch p dng cho nhng mng

nh, khng s dng cho h thng mng ln v phc tp. Bi v :

RIP s dng giao thc nh tuyn theo vct khong cch thng tnt ti nguyn h thng nhng tc ng b gia cc b nh tuyn li chm

m i vi 1 mng ln hay phc tp th li gm nhiu b nh tuyn nn RIP

khng ph hp vi nhng h thng mng lp v phc tp.

RIP gii hn s hop ti a l 15 (bt k mng ch no m c s hop

ln hn 15 th xem nh mng khng n c). S lng 15 hop s khng

khi mun xy dng mt mng ln.

Khi cu trc mng thay i th thng tin cp nht phi c x l trong

ton b h thng, nn iu ny s thc hin rt kh i vi mng ln v s rt

r gy ra hin tng tc nghn trong mng.

Do s dng thut ton nh tuyn theo vct khong cch nn c tc

hi t chm (Trng thi hi t l tt c cc b nh tuyn trong h thng mng

u c thng tin nh tuyn v h thng mng v chnh xc) do vy i vi

mng ln hay phc tp th s mt rt lu mi hi t c.

VI. Kt lun, nh gi v hng pht trin

4.1 Kt lun ,nh gi

SV:


25/25

GIAO THC NH TUYN RIPGiao thc nh tuyn RIP l giao thc ra i lu nht trong cc giao thc

nh tuyn hin ti ang s dng. RIP l giao thc c tnh n nh, d s

dng. RIP s dng thut ton nh tuyn theo vct khong cch. RIP ch

dng cho nhng mng nh v h thng t tr nh.

Documents

49689847-Dinh-tuyen-rip.pdf