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8/3/2019 Tng hp ti liu Mng

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Tm hiu mng m hnh mng LAN

LI M U

Trong cng cuc i mi khng ngng ca khoa hc k thut cng ngh,

nhiu lnh vc v ang pht trin vt bc c bit l lnh vc cng ngh

thng tin. Thnh cng ln nht c th k n l s ra i ca chic my tnh.My tnh c coi l mt phng tin tr gip c lc cho con ngi trong nhiu

cng vic c bit l cng tc qun l. Mng my tnh c sinh t nhu cu

mun chia s v dng chung d liu. My tnh c nhn l cng c tuyt vi gip

to d liu, bng tnh, hnh nh, v nhiu dng thng tin khc, nhng khng cho

php chia s d liu bn to nn. Nu khng c h thng mng, d liu phi

c in ra giy th ngi khc mi c th hiu chnh v s dng c hoc ch

c th sao chp ln a mm v mang n chp vo my ngi khc. Nu ngi

khc thc hin thay i th khng th hp nht cc thay i . Phng thc

lm vic nh vy c gi l lm vic c lp. Nu ngi lm vic mi trng

c lp ni my tnh ca mnh vi my tnh ca nhiu ngi khc, th ta c th

s dng trn cc my tnh khc v c my in. Mng my tnh c cc t chc s

dng ch yu chia s, dng chung ti nguyn v cho php giao tip trc tuyn

bao gm gi v nhn thng ip hay th in t, giao dich bun bn trn mng,

tm kim thng tin trn mng. Mt s doanh nghip u t vo mng my tnh

chun ho cc ng dng chng hn nh: chng trnh x l vn bn, bo mrng mi ngi s dng cng phin bn ca phn mm ng dng d dng hn

cho cng vic. Cc doanh nghip v t chc cng nhn thy s thun li ca

E_mail v cc chng trnh lp lch biu. Nh qun l c th s dng cc chng

trnh tin ch giao tip, truyn thng nhanh chng v hiu qu vi rt nhiu

ngi, cng nh t chc sp xp ton cng ty d dng. Chnh v nhng vai tr

rt quan trng ca mng my tnh vi nhu cu ca cuc sng con ngi, bng

nhng kin thc c hc trng em chn ti Tm hiu m hnh

mng LAN.Nhng do thi gian v kin thc c hn nn bi vit cn hn ch, rt

mong c s gp ca cc thy c gio v em xin chn thnh cm n cc thy

c gio tn tnh gip em hon thnh bi bo co ny.

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Mc LcMc Lc .......................................................................................................... 4

Chng 1 Mt s khi nim v mng my tnh ..............................................6

1.1 Gii thiu s pht trin ca mng ........................................................ 61.2 Khi nim v mng my tnh ............................................................. 7

1.3 Ti sao phi dng mng ....................................................................... 7

1.4 Phn loi mng ..................................................................................... 8

1.4.1 Phn loi theo phm vi a l .......................................................... 8

1.4.2 Phn bit theo phng php chuyn mch ( truyn d liu ) .... ... ..8

1.4.2.1 Mng chuyn mch knh ( circuit - switched network ) ..............81.4.2.2 Mng chuyn mch bn tin ( Message switched network) ...........9

1.4.2.3 Mng chuyn mch gi................................................................ 9

Chng 2. Cc m hnh mng trong LAN ......................................................10

2.1 Kin thc c bn v LAN ..................................................................... 10

2.2 Cc k thut mng cc b ................................................................... 11

2.2.1 Cu trc tp ca mng cc b .................................................... 112.2.1.1 Mng dng sao (Star topology) .................................................. 11

2.2.1.2 Mng dng tuyn (Bus topology) .............................................12

2.2.1.3 Mng dng vng (Ring topology) ............................................... 13

2.2.1.4 Mng dng kt hp .................................................................. 14

2.2.2 Cc phng php truy cp ng truyn .....................................14

2.2.2.1 Phng thc CSMA/CD (Carrier Sense Multiple Access WidthCollision Detection) ................................................................................ 14

2.2.2.2 Phng thc truyn th bi (Token Bus ) ...................................15

2.2.2.3 Phng thc truyn vng th bi (Token Ring) ..........................17

2.2.2.4 Phng thc FDDI...................................................................... 19

2.2.3 H thng cp mng dng cho LAN ................................................20

2.2.3.1 Cp xon .................................................................................... 20

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2.2.3.2 Cp ng trc ..................................................................... 20

2.2.3.3 Cp si quang ............................................................................ 21

2.2.4 Cc thit b dng kt ni mng LAN .........................................22

2.2.4.1 HUB-B tp trung ....................................................................... 22

2.2.4.2 Bridge ........................................................................................ 23

2.2.4.3 Switch - B chuyn mch .......................................................... 26

2.2.4.4 Router - B nh tuyn ............................................................... 26

2.2.4.5 Repeater-B lp tn hiu ............................................................ 29

2.2.4.6 Layer 3 Switch-B chyn mch c nh tuyn ............................29

2.2.5 Cc k thut chuyn mch trong LAN ..........................................30

2.2.5.1 Phn on mng trong LAN ....................................................... 30

2.2.5.1.1 Mc ch ca phn on mng ............................................... 30

2.2.5.1.2 Phn on mng bng Repeater ............................................30

2.2.5.1.3 Phn on mng bng cu ni................................................31

2.2.5.1.4 Phn on mng bng router ................................................. 32

2.2.6.1.5 Phn on mng bng b chuyn mch .................................32

2.2.5.2 Cc ch chuyn mch trong LAN ..........................................33

2.2.5.2.1 Chuyn mch lu v chuyn(Store and forward switching) ....33

2.2.5.2.2 Chuyn mch ngay (Cut through switching) ...........................34

Chng 3. Thit k mng LAN ...................................................................... 34

3.1 M hnh c bn .................................................................................... 34

3.1.1 M hnh phn cp .......................................................................... 34

3.1.2 M hnh an ninh- an ton (Secure model) .....................................36

3.2 Cc yu cu thit k ........................................................................... 36

Cc bc thit k ..................................................................................... 36

3.3.1 Phn tch yu cu: ......................................................................... 36

3.3.2 La chn phn cng (thit b, cng ngh kt ni,...) .....................37

3.3.2 La chn phn mm : ................................................................... 37

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3.3.3 nh gi kh nng, gi thnh: ...................................................... 37

Chng 4. Hoch nh v lp t ................................................................. 39

4.1 Xy dng mng LAN trong qui m 1 to nh ......................................39

4.1.1 Trong h thng mng bao gm: ....................................................39

4.1.2 Phn tch yu cu: ......................................................................... 39

4.2 Thit k h thng: ............................................................................... 41

4.2.1 H thng chuyn mch v nh tuyn trung tm ca LAN ............41

4.2.2 H thng cp ................................................................................ 44

4.3 Card mng .......................................................................................... 44

4.3.1 Vai tr ca card mng ................................................................... 44

4.3.2 Cc cu trc ca card mng ......................................................... 45

4.4 Qun l v cp pht a ch IP ............................................................. 45

4.5 Xy dng h thng tng la kt ni mng vi Internet .....................46

KT LUN ..................................................................................................... 47

H ng pht trin .......................................................................................... 48

Ti liu tham kho: ...................................................................................... 49

Chng 1 Mt s khi nim v mng my tnh

1.1 Gii thiu s pht trin ca mng

Mng my tnh c pht sinh do nhu cu mun chia s v dng chung d

liu. My tnh c nhn l mt cng c tuyt vi gip to d liu, bng tnh, hnh

nh v nhiu dng thng tin khc nhau, nhng khng cho php bn nhanh chng

chia s d liu bn to nn. Nu khng c h thng mng, d liu ch c th

chp ra a mm mang n mt my khc.

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T nm 1960 xut hin cc mng x l trong cc trm cui

(terminal) th ng c ni vo mt my x l trung tm. My x l trung tm

lm tt c mi vic, t qun l cc th tc nhp xut d liu, qun l s ng b

ca cc trm cui ..... cho n vic x l cc ngt t cc trm cui.... nhnnhim v ca my x l trung tm, ngi ta thm vo cc tin x l ni thnh

mng truyn tin, trong cc thit b tp trung v dn knh dng tp trung

trn mt ng truyn cc tn hiu gi ti t trm cui. S khc nhau gia hai

thit b ny l b dn knh c kh nng truyn song song cc thng tin do cc

trm cui gi ti, cn b tp trung khng c kh nng nn phi dng b nh

m lu tr tm thi cc thng tin.

T u nhng nm 70 my tnh c ni vi nhau trc tip to thnh

mt mng my tnh nhm chia s ti nguyn v tng tin cy.

Cng trong nhng nm 70 bt u xut hin khi nim mng truyn thng,

trong cc thnh phn chnh ca n l cc nt mng, c gi l cc b truyn

mch dng hng thng tin n cc ch ca n. Cc nt mng c ni vi

nhau bng ng truyn cn cc my tnh x l thng tin ca ngi s dng

hoc cc trm cui c ni trc tip vo cc nt mng khi cn th trao i

thng tin qua mng. Bn thn cc nt mng thng cng l cc my tnh nn c

th ng thi ng c vai tr my ca ngi x dng.

1.2 Khi nim v mng my tnh

Mng my tnh l mt tp hp cc my tnh v cc thit b ngoi vi c kt

ni vi nhau bng cp sao cho chng c th dng chung d liu.

1.3 Ti sao phi dng mng

Cc t chc s dng mng ch yu chia s, dng chung ti nguyn v cho

php giao tip trc tuyn. Ti nguyn gm c d liu, chng trnh ng dng v

cc thit b ngoi vi nh a ngoi, my in, modem, cn iu khin.......Giao

tip trc tuyn bao gm gi v nhn thng ip hoc th in t.

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1.4 Phn loi mng

1.4.1 Phn loi theo phm vi a l

Mng cc b LAN ( Local Area Network ) : l mng c lp t trong

phm vi hp, khong cch gia cc nt mng nh hn 10 Km.

Mng th MAN ( Metropolitan Area Network) : L mng c ci t

trong phm vi mt th hoc mt trung tm kinh t - x hi c bn knh khong

100 Km tr li.

Mng din rng WAN ( Wide Area Network ) : Phm vi ca mng c th

vt qua bin gii quc gia v thm ch c chu lc.

Mng ton cu GAN (Global Area Network ) : L mng c thit lp trnphm vi tri rng khp cc chu lc trn tri t.

1.4.2 Phn bit theo phng php chuyn mch ( truyn d liu )

1.4.2.1 Mng chuyn mch knh ( circuit - switched network )

Trong trong trng hp ny khi c hai trm cn trao i thng tin vi nhau

th gia chng s c thit lp mt knh (circuit) c nh v duy tr cho n khi

mt trong hai bn ngt lin lc. Cc d liu ch c truyn theo con ng c

nh.

Hnh 1. Mng chuyn mch knhMng chuyn mch knh c tc truyn cao v an ton nhng hiu xut x

dng ng truyn thp v c lc knh b b khng do c hai bn u ht thngtin cn truyn trong khi cc trm khc khng c php s dng knh truyn nyv phi tiu tn thi gian thit lp con ng (knh) c nh gia 2 trm.

Mng in thoi l v d in hnh ca mng chuyn mch knh.

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A

S3

S4S2

S1 B

S5

S6

Data1Data3

Data2


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1.4.2.2 Mng chuyn mch bn tin ( Message switched network)

Thng tin cn truyn c cu trc theo mt phn dng c bit gi l bn

tin. Trn bn tin c ghi a ch ni nhn, cc nt mng cn c vo a ch ni

nhn chuyn bn tin ti ch. Tu thuc vo iu khin v mng, cc thng tinkhc nhau c th c gi i theo cc con ng khc nhau

u im :

-Hiu xut s dng ng truyn cao v khng b chim dng c quyn m

c phn chia gia cc trm

-Mi nt mng (hay nt chuyn mch bn tin) c th lu d thng bo cho

n khi knh truyn ri mi gi thng bo i, do gim c tnh trng tc

nghn mng.

-C iu khin vic truyn tin bng cch sp xp u tin cho cc thng

bo.

-C th tng hiu xut s dng gii thng ca mng bng cch gn a ch

qung b gi thng bo ng thi n nhiu ch.

Nhc im :

Phng php chuyn mch bn tin l khng hn ch kch thc ca ccthng bo, lm cho ph tn lu tr tm thi cao v nh hng n thi gian p

ng v cht lng truyn i. Mng chuyn mch bn tin thch hp vi cc dch

v thng tin kiu th in t hn l vi cc p dng c tnh thi gian thc v tn

ti tr nht nh do lu tr v x l thng tin iu khin ti mi nt.

1.4.2.3 Mng chuyn mch gi

Phng php ny mi thng bo c chia thnh nhiu phn nh hn gi l

cc gi tin (pachet) c khun dng quy nh trc. Mi gi tin cng cha cc

thng tin iu khin, trong c a ch ngun (ngi gi) v ch ( ngi nhn)

ca gi tin. Cc gi tin v mt thng bo no c th c gi i qua mng

n ch bng nhiu con ng khc nhau. Cn c vo s th t cc gi tin c

ti to thnh thng tin ban u.

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Phng php chuyn mach bn tin v phng php chuyn mch gi l gn

ging nhau. im khc bit l cc gi tin c gii hn kch thc ti a sao cho

cc nt mng c th x l ton b thng tin trong b nh m khng cn phi lu

tr tm thi trn a. Nn mng chuyn mch gi truyn cc gi tin qua mngnhanh hn v hiu qu hn so vi chuyn mch bn tin.

Chng 2. Cc m hnh mng trong LAN

2.1 Kin thc c bn v LAN

Mng cc b (LAN) l h truyn thng tc cao c thit k kt ni

cc my tnh v cc thit b x l d liu khc cng hot ng vi nhau trong

mt vc a l nh nh mt tng ca mt to nh, hoc trong mt to nh.Mt

s mng LAN c th kt ni li vi nhau trong mt khu lm vic.

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Cc mng LAN tr nn thng dng v n cho php nhng ngi s dng

dng chung nhng ti nguyn quan trng nh my in, a CD-ROM, cc phn

mm ng dng v nhng thng tin cn thit khc. Trc khi pht trin cng ngh

LAN cc my tnh hot ng c lp vi nhau,b hn ch bi s lng ccchng trnh tin ch, sau khi kt ni mng hiu qu ca chng tng ln gp i.

2.2 Cc k thut mng cc b

2.2.1 Cu trc tp ca mng cc b

Cu trc tp (network topology) ca LAN l kin trc hnh hc th hin

cch b tr cc ng cp, xp xp cc my tnh kt ni thnh mng hon

chnh.Hu ht cc mng LAN ngy nay u c thit k hot ng da trn

mt cu trc mng nh trc. in hnh v s dng nhiu nht l cu trc : dng

sao, dng tuyn tnh, dng vng cng vi nhng cu trc kt hp ca chng.

2.2.1.1 Mng dng sao (Star topology)

Mng sao bao gm mt b kt ni trung tm v cc nt. Cc nt ny l cc

trm u cui, cc my tnh v cc thit b khc ca mng. B kt ni trung tm

ca mng iu phi mi hot ng trong mng.

Hnh 2. Cu trc mng sao

Mng dng sao cho php ni cc my tnh vo mt b tp trung bng cp,

gii php ny cho php ni trc tip my tnh vi b tp trung khng cn thng

qua trc bus, nn trnh c cc yu t gy ngng tr mng.

M hnh kt ni dng sao ny tr ln ht sc ph bin. Vi vic s dng

cc b tp trung hoc chuyn mch, cu trc sao c th c m rng bng cch

t chc nhiu mc phn cp, do d dng trong vic qun l v vn hnh.

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u im :

-Hot ng theo nguyn l ni song song nn nu c mt thit b no

mt nt thng tin b hng th mng vn hot ng bnh thng.

-Cu trc mng n gin v cc gii thut ton n nh.

-Mng c th d dng m rng hoc thu hp.

-D dng kim sot ni, khc phc s c. c bit do s dng kt ni im -

im nn tn dng c ti a tc ca ng truyn vt l.

Nhc im :

-Kh nng m rng ca ton mng phc thuc vo kh nng ca trung tm.

-Khi trung tm c s c th ton mng ngng hot ng.

-Mng yu cu ni c lp ring r tng thit b cc nt thng tin n trung

tm.

- di ng truyn ni mt trm vi thit b trung tm b hn ch (trong

vng 100m vi cng ngh hin tai).

2.2.1.2 Mng dng tuyn (Bus topology)

Thc hin theo cch b tr ngang hng, cc my tnh v cc thit b khc.

Cc nt u c ni v vi nhau trn mt trc ng dy cp chnh chuyn

ti tn hiu. Tt c cc nt u s dng chung ng dy cp chnh ny.

hai u dy cp c bt bi mt thit b gi l terminator. Cc tn hiu v

d liu khi truyn i u mang theo a ch ni n.

terminator

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Hnh 3. Cu trc mng hnh tuyn

u im :

-Loi cu trc mng ny dng dy cp t nht.

-Lp t n gin v gi thnh r.

Nhc im :

-S n tc giao thng khi di chuyn d liu vi lu lng ln.

-Khi c s c hng hc on no th rt kh pht hin, li trn ng

dy cng lm cho ton b h thng ngng hot ng. Cu trc ny ngy nay t

c s dng.

2.2.1.3 Mng dng vng (Ring topology)

Mng dng ny b tr theo dng xoay vng, ng dy cp c thit k lm

thnh mt vng trn khp kn, tn hiu chy quanh theo mt vng no . Cc

nt truyn tn hiu cho nhau mi thi im ch c mt nt m thi. D liu

truyn i phi c km theo a ch c th ca mi trm tip nhn.

u im:-Mng dng vng c thun li c th m rng ra xa, tng n dy cn thit

t hn so vi hai kiu trn.

-Mi trm c th t c tc ti a khi truy nhp.

Nhc im : ng dy phi khp kn, nu b ngt mt ni no th

ton b h thng cng b ngng.

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Hnh 4. Cu hnh mng vng

2.2.1.4 Mng dng kt hp

L mng kt hp dng sao v tuyn ( star/bus topology) : Cu hnh mng

dng ny c b phn tch tn hiu (spitter) gi vai tr thit b trung tm, h thng

dy cp mng c th chn hoc Ring Topology hoc Linear Bus Topology. u

im ca cu hnh ny l mng c th gm nhiu nhm lm vic cch xa nhau,

ARCNET l mng dng kt hp Star/Bus Topology. Cu hnh dng ny a li

s uyn chuyn trong vic b tr ng dy tng thch d dng i vi bt k

to nh no.

Kt hp cu hnh sao v vng (Star/Ring Topology). Cu hnh dng kt hp

Star/Ring Topology, c mt th bi lin lc c chuyn vng quanh mt ci b

tp trung.

2.2.2 Cc phng php truy cp ng truyn

Khi c ci t vo trong mng, cc trm ny tun theo quy tc nh trc

c th s dng ng truyn, l phng thc truy nhp. Phng thc truynhp c nh ngha l cc th tc u hng trm lm th no v lc no c

th thm nhp vo ng dy cp gi hay nhn cc gi thng tin

2.2.2.1 Phng thc CSMA/CD (Carrier Sense Multiple Access WidthCollision Detection)

Phng thc ny thng dng cho mng c cu trc hnh tuyn, cc my

trm cng chia s mt knh truyn chung, cc trm u c c hi thm nhp

ng truyn nh nhau (Multiple Access).

Tuy nhin ti mt thi im th ch c mt ng truyn d liu m thi.

Trc khi truyn d liu, mi trm phi lng nghe ng truyn chc chn

ng truyn ri ( Carrier Sense).

Trong trng hp hai trm thc hin vic truyn d liu ng thi, xung t

d liu s xy ra, cc trm tham ra phi pht hin c s xung t v thng bo

vi cc trm khc gy ra xung t (Collision Detection), ng thi cc trm phi

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ngng thm nhp, chi i ln sau trong khong thi gian ngu nhin no ri

mi tip tc truyn.

Khi lu lng cc gi tin cn di chuyn trn mng qu cao, th vic xung t

c th xy ra vi s lng ln hn dn n lm chm tc truyn tin ca hthng.

2.2.2.2 Phng thc truyn th bi (Token Bus )

Nguyn l hot ng ca phng php ny l : cp pht quyn truy nhp

ng truyn ca cc trm ang c nhu cu truyn d liu, mt th bi c lu

chuyn trn vng trn logic thit lp bi cc trm . Khi mt trm nhn th bi

th n c quyn s dng ng truyn trong mt thi gian xc nh. Trong thi

gian n c th truyn mt hoc nhiu n v d liu. Khi ht d liu hoc

ht thi gian cho php, trm phi chuyn th bi n trm tip theo trong vng

logic. Nh vy, cng vic u tin l thit lp vng logic ( hay cn gi l vng

o) bao gm cc trm ang c nhu cu truyn d liu c xc nh v tr theo

mt chui th t m trm cui cng ca chui s tip lin sau bi trm u tin.

Mi trm c bit a ch ca cc trm k trc v sau n. Th t ca cc trm

trn vng logic c th c lp vi th t vt l. Cc trm khng hoc cha c

nhu cu truyn d liu th khng c a vo vng logic m chng ch c thnhn d liu.

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B C DA

H G F E

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ng truyn vt l

vng logic

Hnh 5. Cu trc mng vng logic

Vic thit lp vng logic trong chng trnh l khng kh, nhng vic duy

tr n theo trng thi thc t ca mng mi l kh. Ta phi thc hin cc bc

sau:

-B xung mt trm vo mng logic : Cc trm nm ngoi vng logic cn

c xem xt nh k nu c nhu cu truyn d liu th b sung vo vng

logic.

-Loi b mt trm khi vng logic : Khi mt trm khng cn nhu cu truyn

d liu cn loi n ra khi vng logic ti u ho vic iu khin truy nhp

bng th bi.

-Qun l li : Mt s li c th xy ra, chng hn trng a ch hoc t vng

.

-Khi to vng logic : Khi ci t mng hoc sau khi t vng cn phi khi

to li vng.

Cc gii thut cho cc chc nng trn c khuyn ngh nh sau:

- thc hin b sung trm vo vng logic, mi trm c trch nhim nh

k to c hi cho cc trm mi nhp, vo vng. Khi chuyn th bi i, trm s

gi theo mt thng bo tm trm ng sau mi cc trm gi yu cu nhp

vng. Nu trong mt thi gian xc nh trc m khng c yu cu no th trm

s chuyn th n trm k sau n nh thng l. Nu c yu cu th trm gi th

bi s ghi nhn trm yu cu tr thnh trm ng k sau n v chuyn th bi

mi ny. Nu c hn mt trm yu cu nhp vng th trm gi th bi s phi la

chn mt gii thut no .

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-Vic loi b trm ra khi vng logic n gin hn nhiu. Mt trm mun ra

khi vng s i n khi nhn c th bi s gi thng bo ni trm ng sau

ti trm k trc n yu cu trm ny ni trc tip vi trm k sau n.

-Vic qun l li mt trm gi th bi phi gii quyt nhiu tnh hung btng. Chng hn, trm nhn c tn hiu cho thy c trm khc c th bi.

Lp tc n phi chuyn sang trng thi nghe. Hoc sau khi kt thc truyn d

liu, trm phi chuyn th bi n trm k sau n v tip tc nghe xem trm k

sau c hot ng hay khng. Trng hp trm k sau n b h hng th phi

tm cch vt qua nt hng , c gng tm c trm hot ng gi th

bi ti.

-Vic khi to vng logic c thc hin khi mt hoc nhiu trm pht hinbng bus khng hot ng trong mt thi gian vt qua mt gi tr ngng

(time-out) cho trc - th bi b mt. C nhiu nguyn nhn, chng hn mng

b mt ngun hoc trm gi th bi b hng. Lc trm pht hin s gi i

thng bo yu cu th bi ti mt trm c ch nh trc c trch nhim sinh

th bi mi v chuyn i theo vng logic.

2.2.2.3 Phng thc truyn vng th bi (Token Ring)

Phng php ny cng da trn nguyn tc dng th by cp pht quyntruy nhp ng truyn. Nhng y th bi lu chuyn theo vng vt l ch

khng cn lp vng logic nh i vi phng php Token Bus.

Th bi l n v d liu c bit trong c mt bt c bit biu din

trmg thi s dng ca n (bn hoc ri). Mt trm mun truyn d liu th phi

i n khi nhn c mt th bi "ri". Khi trm s i bt trng thi ca th

bi thnh "bt" v truyn mt n v d liu vi th bi i theo chiu ca vng.

Lc ny khng cn th bi ri trn vng, do cc trm c d liu cn chuyncng phi i. D liu n trm ch s c sao li, sau cng th bi i tip

cng vi th bi v trm ngun. Trm ngun s xo b d liu v i bt trng

thi tr v ri v cho lu chuyn tip trn vng cc trm khc c th nhn

c quyn truyn d liu. Qu trnh m t trn c minh ho trong ( hnh 5).

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Hnh 6. Hot ng ca phng php Token Ring

S quay tr v ca ngun d liu v th bi nhm to mt c ch bo nhn

t nhin : trm ch c th gi vo n v d liu (phn header) cc thng tin v

kt qu tip nhn d liu ca mnh. Cc thng tn c th l :

-Trm ch khng tn ti hoc khng hot ng.

-L trm ch tn ti nhng khng c sao chp.

-D liu c tip nhn.

-C li xy ra.

Phng php ny gii quyt hai vn c th dn n ph v h thng. Mt

vic l mt th bi lm cho trn vng khng cn th bi lu chuyn na. Hai l

mt th bi lu chuyn khng dng trn vng trn. C th c nhiu gii php

khc nhau cho hai vn ny. Sau y l mt gii php c ngh :-i vi vn mt th bi, c th quy nh trc mt trm iu khin ch

ng (active monitor). Trm ny s pht hin tnh trng mt th bi bng cch

dng c ch ngng thi gian (time out) v phc hi bng cch pht i mt th

bi ri mi.

-i vi th bi bn lu chuyn khng dng, trm monitor s dng mt bt

trn th bi (gi l monitor bt) nh du (t gi tr 1) khi gp mt th bi bn

i qua n. Nu n gp li mt th bi bn vi bt nh du th c ngha l

18 | P a g e

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B

A C

D

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trm ngun khng nhn li c n v d liu ca mnh v th bi bn c

quay vng mi. Lc , trm monitor s i bt trng thi ca th bi thnh ri v

chuyn tip tren vng. Cc trm cn li trn vng s c vai tr b ng: chng

theo di pht hin tnh trnh s c ca trm monitor ch ng v thay th vai tr. Cn c mt gii thut chn trm thay th cho trm monitor hng

2.2.2.4 Phng thc FDDI

FDDI l k thut dng trong cc mng cu trc vng, di chuyn th bi tc

cao bng phng tin cp si quang.

FDDI s dng h thng chuyn th bi trong c ch vng kp. Lu thng

trn mng FDDI bao gm hai lung ging nhau theo hai hng ngc nhau.

FDDI thng c dng vi mng trc trn nhng mng LAN cng xut

thp c th ni vo. Cc mng LAN hi tc truyn d liu cao di thng

ln c th s dng FDDI.

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Hnh 7. Cu trc mng dng vng ca FDDI

2.2.3 H thng cp mng dng cho LAN

2.2.3.1 Cp xon

y l loi cp gm 2 ng dy bng ng c xon vo nhau lm gim

nhiu in t gy ra bi mi trng xung quanh v gia chng vi nhau. Hin

nay c 2 loi cp xon l cp c bc kim loi (STP-Shield Twisted Pair) v cp

khng bc kim loi (UTP-Unshield Twisted Pair).

Cp c bc kim loi (STP): Lp bc bn ngoi c tc dng chng nhiu in

t, c loi c mt i dy xon vo nhau v c loi c nhiu i dy xon vo

nhau.Cp khng bc kim loi (UTP) : tnh tng t nh STP nhng km hn v

kh nng chng nhim t v suy hao v khng c v bc.

STP v UTP c 2 loi (Category-Cat) thng dng:

-Loi 1 v 2 (Cat1 & Cat2) : thng dng cho truyn thoi v nhng ng

truyn tc thp (nh hn 4Mb/s).

-Loi 3 (Cat3) : Tc truyn d liu khong 16Mb/s, n l chun hu ht

cho cc mng in thoi.

-Loi 4 (Cat4) : Thch hp cho ng truyn 20Mb/s.



y l loi cp r , d lp t tuy nhin n d b nh hng ca mi trng.

2.2.3.2 Cp ng trcCp ng trc c 2 ng dy dn v chng c cng 1 trc chung , 1 dy

dn trung tm (thng l dy ng cng) ng dy cn li to thnh ng ng

bao xung quanh dy dn trung tm ( dy dn ny c th l dy bn kim loi v v

n c chc nng chng nhim t nn cn gi l lp bc kim). Gia 2 dy dn

trn c 1 lp cch ly, v bn ngoi cng l lp v plastic bo v cp.

Cp ng trc c suy hao t hn so vi cc loi cp ng khc ( nh cp

xon i) do t b nh hng ca mI trng. Cc mng cc b s dng cp ng

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trc c th c kch thc trong phm vi vi ngn mt, cp ng trc c s

dng nhiu trong cc mng dng ng thng.

Hai loi cp thng c s dng l cp ng trc mng v cp ng trc

dy. ng knh cp ng trc mng l 0,25 inch v dy l 0,5 inch. C hai loicp u lm vic cng tc nhng cp ng trc mng c hao suy tn hiu

ln hn.

Hin nay c cp ng trc sau :

-RG -58,50 m: dng cho mng Ethernet

-RG - 59,75 m: dng cho truyn hnh cp

Cc mng cc b s dng cp ng trc c di thng t 2,5 - 10Mbps, cpng trc c suy hao t hn so vi cc loi cp ng khc v n c lp v bc

bn ngoi, di thng thng ca mt on cp ni trong mng l 200m,

thng s dng cho dng Bus.

2.2.3.3 Cp si quang

Cp si quang bao gm mt dy dn trung tm (l mt hoc mt b si thu

tinh c th truyn dn tn hiu quang) c bc mt lp v bc c tc dng phn

x cc tn hiu tr li gim s mt mt tn hiu. Bn ngoi cng l lp vplastic bo v cp. Cp si quang khng truyn dn c cc tin hiu in m

ch truyn cc tn hiu quang v khi nhn chng s li chuyn i tr li thnh

cc tn hiu in. Cp quang c ng knh t 8.3 - 100 micron, do ng knh

li thu tinh c kch thc rt nh nn rt kh khn cho vic u ni, n cn

cng ngh c bit vi k thut cao v chi ph cao.

Di thng ca cp quang c th ln ti hng Gbps v cho php khong cch

i cp kh xa do suy hao tn hiu trn cp rt thp. Ngoi ra v cp si quangkhng dng tn hiu in t truyn d liu nn n hon ton khng b nh

hng ca nhiu in t v tn hiu truyn khng b pht hin v thu trn bng

cc thit b in t ca ngi khc.

Nhc im ca cp quang l kh lp t v gi thanh cao, nhng nhn

chung cp quang thch hp cho mi mng hin nay v sau ny.

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Cc loi cp Cp xon cp Cp ng trcmng

Cp ng trcdy

Cp quang

Chi tit Bng ng, co4 cp dy

(loi 3,4,5)

Bng ng, 2dy, ng

knh 5mm

Bng ng, 2dy, ng

knh 10mm

Thu tinh 2si

Chiu dion ti a

100m 185m 500m 1000m

S u ni tia trn mton

2 30 100 2

Chy 10Mbps c c c c

Chy 100

Mbps

c c c c

Chng nhiu Tt Tt Tt Tt

Bo mt Trung bnh Trung bnh Trung bnh Hon ton

tin cy Tt Trung bnh Kh Kh

Khc phc li Tt Khng tt Khng tt Tt

Qun l D dng Kh Kh Trung bnh

Chi ph chomt trm

Rt thp Thp Trung bnh Cao

2.2.4 Cc thit b dng kt ni mng LAN

2.2.4.1 HUB-B tp trung

Hub l 1 trong nhng yu t quan trng nht ca LAN , y l im kt ni

dy trung tm ca mng, tt c cc trm trn mng LAN c kt ni thng quahub. Hub thng c dng ni mng, thng qua nhng u cm ca n

ngi ta lin kt vi cc my tnh di dng hnh sao.

Mt hub thng thng c nhiu cng ni vi ngi s dng gn my tnh

v cc thit b ngoi vi. Mi cng h tr 1 b kt ni dng cp dy xon

10BASET t mi trm ca mng.

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Khi tn hiu c truyn t mt trm ti hub, n c lp li trn khp cc

cng khc ca hub. Cc hub thng minh c th nh dng, kim tra, cho php

hoc khng cho php bi ngi iu hnh mng t trung tm qun l hub.

Nu phn loi theo phn cng th c 3 loi hub:

-Hub n (stand alone hub)

-Hub modun (modular hub) Rt ph bin cho cc h thng mng v n c

th d dng m rng v lun c chc nng qun l, modular c t 4 ti 14 khe

cm, c th lp thm cc modun Ethernet 10BASET.

-Hub phn tng (stackable hub) l l tng cho nhng c quan mun u

t ti thiu ban u nhng li c k hoch pht trin sau ny.

Phn loi theo kh nng c 2 loi:

-Hub b ng (Passive hub) : hub b ng khng cha cc linh kin in t

v cng khng s l cc tn hiu d liu, n c chc nng duy nht l t hp tn

hiu t 1 s on cp mng.

-Hub ch ng (Active hub): c cc linh kin in t c th khuych i

v x l cc tn hiu in t truyn gia cc thit b mng. Qu trnh s l d liu

c gi l ti sinh tn hiu, n lm cho tn hiu tr nn tt hn, t nhy cm vili do vy khong cch gia cc thit b c th tng ln. u im ca hub ch

ng cng ko theo gi thnh ca n cao hn so vi hub b ng. Cc mng

Tokenring c xu hng dng hub ch ng.

2.2.4.2 Bridge

Bridge l mt thit b c s l ding ni 2 mng ging hoc khc nhau, n

c th dng c vi cc mng c cc giao thc khc nhau. Cu ni hot ng

trn tng lin kt d liu nn khng nh b tip sc phi pht li tt c nhng g

n nhn c th cu ni c cc gi tin ca tng lin kt d liu trong m hnh

OSI v s l chng trc khi quyt nh c chuyn i hay khng.

Khi nhn c cc gi tin bridge chn lc v ch chuyn nhng gi tin m

n thy cn thit. iu ny cho php bridge tr nn c ch khi ni mt vi mng

vi nhau v cho php n hot ng mt cch mm do.

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thc hin iu ny trong bridge mi u kt ni c 1 bng cc a ch

cc trm c kt ni vo vi n, khi hot ng cu ni xem xt mi gi tin n

nhn c bng cch c a ch ca ni gi v ni nhn v da trn bng a ch

pha nhn c gi tin n quyt nh gi gi tin hay khng v b xung vo bnga ch.

Khi c a ch ni gi bridge kim tra xem trong bng a ch ca phn

mng nhn c gi tin c a ch hay khng, nu khng c th bridge t ng

b xung bng a ch ( c ch c gi l t hc ca cu ni).

Hnh 8. hot ng ca cu ni

Khi c a ch ni gi bridge kim tra xem trong bng a ch ca phn

mng nhn c gi tin c a ch hay khng, nu c th bridge s cho rng

l gi tin ni b thuc phn mng m gi tin n nn khng chuyn gi tin i,

nu ngc li th bridge mi chuyn sang phi bn kia. y chng ta thy 1

trm khng cn thit chuyn thng tin trn ton mng m ch trn phn mng ctrm nhn m thi.

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Hnh 9. Hot ng ca Bridge trong m hnh OSI

trnh mt bridge ngi ta a ra 2 khi nim lc v vn chuyn.

-Qu trnh x l mi gi tin c gi l qu trnh lc th hin trc tip kh

nng hot ng ca bridge.

-Tc chuyn vn c th hin s gi tin trn giy trong th hin kh

nng ca bridge chuyn cc gi tin t mng ny sang mng khc.

Hin nay c 2 loi bridge ang c s dng l bridge vn chuyn v bridge

bin dch. Bridge vn chuyn dng ni 2 mng cc b cng s dng 1 giao

thc truyn thng ca tng lin kt d liu, tuy nhin mi mng c th s dng

loi dy ni khc nhau. Bridge vn chuyn khng c kh nng thay i cu trc

cc gi tin m n nhn c, n ch quan tm ti vic xem xt v vn chuyn gi

tin i.

Bridge bin dch dng ni 2 mng cc b c giao thc khc nhau c kh

nng chuyn 1 gi tin thuc mng ny sang mng khc trc khi chuyn qua.

Ngi ta s dng Bridge trong cc trng hp sau:

-M rng mng hin ti khi t ti khong cch ti a do bridge sau khi

s l gi tin pht li gi tin trn phn mng cn li nn tn hiu tt hn b tip

sc.

-Gim bt tc nghn mng khi c qu nhiu trm bng cch s dung bridge,

khi chng ta chia mng thnh nhiu phn bng cc bridge, cc gi tin trong

ni b trong phn mng s khng c php qua phn mng khc.

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ni cc mng c giao thc khc nhau. Mt vi bridge c kh nng la

chn i tng vn chuyn. N c th ch vn chuyn cc gi tin ca nhng a

ch xc nh.

2.2.4.3 Switch - B chuyn mch

B chuyn mch l s tin ho ca cu, nhng c nhiu cng v dng cc

mch tch hp nhanh gim tr ca vic chun khung d liu.

Switch gia bng a ch MAC ca mi cng v thc hin giao thc

Spanning-tree. Switch cng hot ng tng lin kt d liu v trong sut cc

giao thc tng trn.

2.2.4.4 Router - B nh tuynRouter l 1 thit b hot ng trn tng mng, n c th tm c ng i

tt nht cho cc gi tin qua nhiu kt ni i t trm gi thuc mng u n

trm nhn thuc mng cui. Router c th c s dng trong vic ni nhiu

mng vi nhau v cho php cc gi tin c th i theo nhiu ng khc nhau v

ti ch.

Khc vi bridge hot ng trn tng lin kt d liu nn bridge phi x l

mi gi tin trn ng truyn th router c a ch ring bit v n ch tip nhnv x l cc gi tin gi n n m thi. Khi mt trm mun gi gi tin qua router

th n phi gi gi tin vi a ch trc tip ca router (trong gi tin phi cha

cc thng tin khc v ch n) v khi gi tin n router th router mi x l v

gi tip.

Khi x l 1 gi tin router phi tm c ng i ca gi tin qua mng.

lm c iu router phi tm c ng i tt nht trong mng da trn cc

thng tin m n c v mng, thng thng trn mi router c 1 bng ch ng(router table). Da trn d liu v router gn v cc mng trong lin mng,

router tnh c bng ch ng ti u da trn 1 thut ton xc nh trc.

Ngi ta phn chia router thnh 2 loi l router c ph thuc giao thc (The

protocol dependent router) v router khng ph thuc giao thc (The protocol

independent router) da vo phng thc s l cc gi tin router c ph thuc

giao thc : ch thc hin tm ng v truyn gi tin t mng ny sang mng

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khc ch khng chuyn i phng cch ng gi ca gi tin cho nn c hai

mng phi dng chung 1 giao thc truyn thng.

Router khng ph thuc vo giao thc: c th lin kt cc mng dng giao

thc truyn thng khc v c th chuyn i gi tin ca giao thc ny sang gitin ca giao thc kia, n cng chp nhn kch thc cc gi tin khc nhau.

ngn chn vic mt mt s liu router cn c th nhn bit ng no c th

chuyn vn v ngng chuyn vn khi ng tc.

Hnh 10. Hot ng ca Router trong m hnh OSI

Cc l do s dng router:

Router c cc phn mm lc u vit hn l bridge do cc gi tin mun i qua

router cn phi gi trc tip n n nn gim c s lng gi tin qua n.

Router thng c s dng trong khi ni cc mng thng qua cc ng dy

thu bao t tin do n khng truyn d ln ng truyn.

-Router c th dng trong mt lin mng c nhiu vng, mi vng c giao

thc ring bit.

-Router c th xc nh c ng i an ton v tt nht trong mng nn

an ton ca thng tin c bo m hn.

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Trong mt mng phc hp khi cc gi tin lun chuyn cc ng c th gy

nn tnh trng tc nghn ca mng th cc router c th c ci t cc phng

th nhm trnh c tc nghn.

Cc phng thc hot ng ca router : l phng thc m router c thni vi cc router khc qua chia s thng tin v mng hin c. Cc chng

trnh chy tren router lun xy dng bng chi tit ng qua vic trao i cc

thng tin vi cc router khc.

-Phng thc vector khong cch : Mi router lun lun truyn i thng tin

v bng ch ng ca mnh trn mng, hng qua cc router khc s cp nht

bng ch ng cho mnh.

-Phng thc trng thi tnh : Router ch truyn cc thng bo khi c phthin c s thay i trong mng v ch khi cc router khc cp nht li bng

ch ng, thng tin truyn i khi thng l thng tin v ng truyn .

Hnh 11. Bng nh tuyn ca Router

Mt s giao thc hot ng chnh ca router:

RIP (Routing information protocol) c pht trin bi Xeronx Network

System v s dng SPX/IPX v TCP/IP. RIP hot ng theo phng thc vct

khong cch.

28 | P a g e

Network2

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-NLSP (Netware Link Service Protocol) c pht trin bi Novell dng

thay th RIP hot ng theo phng thc vecs t khong cch, mi router c

bit cu trc ca mng v vic truyn cc bng ch ng.

-OSPF (Open Shortest Path First) l mt phn ca TCP/IP vi phng thctrng thi tnh, trong xt ti u tin, gi dng truyn mt truyn thng.

-IS - IS (Opent System Interconnection Intermediate System To Intermediate

System) l mt phn ca TCP/IP vi phng thc trng thi tnh, trong xt ti u

tin, gi dng truyn mt truyn thng.

2.2.4.5 Repeater-B lp tn hiu

Repeater l mt loi thit b phn cng n gin nht trong cc thit b lin

kt mng, n c hot ng trong tng vt l ca m hnh OSI. Khi repeater

nhn c 1 tn hiu t 1 pha ca mng th n s pht tip vo pha kia ca

mng.

Repaeter khng c s l tn hiu m n ch loi b cc tn hiu mo nhiu,

khuych i tn hiu b xuy hao (v pht vi khong cch xa) v khi phc

li tn hiu ban u. Vic s dng repeater lm tng thm chiu di ca mng.

Vic s dng repeater khng thay i ni dung cc tn hiu i qua nn n chc dng ni hai mng c cng giao thc truyn thng (Ethernet hay token

ring) v khng th ni 2 mng c giao thc truyn thng khc nhau. Thm na

repeater khng lm thay i khi lng chuyn vn trn mng nn vic s dng

khng tnh ton n trn mng ln s hn ch hiu nng ca mng. Khi la chn

s dng repeater cn lu la chn loi c tc chuyn vn vi tc ca

mng.

2.2.4.6 Layer 3 Switch-B chyn mch c nh tuynSwitch L3 c th chy giao thc c nh tuyn tng mng, tng 3 ca m

hnh 7 tng OSI, Switch L3 c th c cc cng WAN ni cc LAN khong

cch xa. Thc cht n c b sung thm tnh nng ca router.

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2.2.5 Cc k thut chuyn mch trong LAN

2.2.5.1 Phn on mng trong LAN

2.2.5.1.1 Mc ch ca phn on mng

Mc ch l phn chia bng thng hp l p ng nhu cu ca cc ng dng

trong mng. ng thi tn dng hiu qu nht bng thng ang c. thc hin

tt iu ny cn hiu r khi nim: Min sung t (collision domain) min

qung b (broadcast domain)

-Min xung t (cn c gi l min bng thng - bandwidth domain)

Nh m t trong hot ng ca m hnh Ethernet, hin tng sung t xy

ra khi hai trm trong cng mt phn on mng ng thi truyn khung. Minxung t c nh ngha l vng mng m trong cc khung c th gy xung

t vi nhau. Cng nhiu trm trong cng mt min xung t th x lm tng

xung t v lm gim tc truyn, v th m min xung t cn gi l min

bng thng (cc trm trong cng min ny s chia s bng thng ca min).

-Min qung b (boardcast domain):

Min qung b c nh ngha l tp hp cc thit b m trong khi mt

thit b pht i mt khung qung b (boardcast) th tt c cc thit b cn li unhn c.

Khi s dng cc thit b kt ni khc nhau, ta s phn chia mng thnh nhiu

min xung t v min qung b khc nhau.

2.2.5.1.2 Phn on mng bng Repeater

Thc cht repeater khng phn on mng m ch m rng on mng v mt

vt l. Ni chnh xc repeater cho php m rng min xung t.H thng 10baset s dng hub nh l mt b repeater nhiu cng. Cc my

trm cng ni vi mt hub s thuc cng 1 min xung t.

Gi s 8 trm ni cng 1 hub 10baset tc 10Mb/s, v ti mt thi im ch

c mt trm c truyn khung ln bng thng trung bnh mi trm c c l:

10Mb/s : 8 trm = 1,25Mbps/1trm

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Hnh12 Min xung t v min qung b khi phn on mng bng Repeater

Ch : khi s dng repeater m rng mng, th khong cch xa nht gia

hai my trm s b hn ch.

2.2.5.1.3 Phn on mng bng cu ni

Cu ni hot ng tng 2 ca m hnh OSI, c kh nng kim tra phn a

ch MAC trong khung, v da vo a ch ngun, ch, n s a ra quyt nh

y khung ny ti u. Quan trng l qua ta c th lin kt cc min xung t

vi nhau trong cng mt min qung b m cc min xung t ny vn c lp

vi nhau.

Khc vi trng hp s dng repeater trn, bng thng lc ny ch b chias trong tng min xung t, mi my trm c s dng nhiu bng thng hn.

Li ch khc ca vic s dng cu l ta c 2 min xung t ring bit nn mi

min c ring gi tr slottime do vy c th m rng ti a cho tng min.

Tuy nhin vic s dng cu cng b gii hn bi qui tc 80/20. Theo qui tc

ny, cu ch hot ng hiu qu khi c 20% ti ca phn on khi qua cu 80% l

ti trong ni b phn on.

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Hnh 13. Min xung t v qung b khi s dng bridge

Trng hp ngc li vi qui tc ny ,hai phn on kt ni bi cu c th

xem nh cng 1 phn on, khng c li g v bng thng.

2.2.5.1.4 Phn on mng bng router

Router hot ng tng 3 trong m hnh OSI, c kh nng kim tra header

ca gi IP nn a ra quyt nh. n v d liu m b nh tuyn thao tc l cc

gi IP (cc b chuyn mch v cu ni thao tc vi cc khung tin).

B nh tuyn ng thi to ra min xung t v min qung b ring.

Hnh 14 Phn on mng bng Router

2.2.6.1.5 Phn on mng bng b chuyn mch

B chuyn mch l mt thit b phc tp nhiu cng cho php cu hnh

theo nhiu cch khc nhau. C th cu hnh n tr thnh nhiu cu o nh sau:

32 | P a g e

BD1

BD2

BD1BD

3

BD2

BD3

Min xungtMin qung b


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Hnh 15. Cu hnh b chuyn mch thnh nhiu cu o

Bng tng kt thc hin phn on mng bng cc thit b kt ni khc nhau:

Thit b Min xung t Min qung b

Repeater Mt Mt

Bridge Nhiu MtRouter Nhiu Nhiu

Switch Nhiu Mt hoc nhiu

2.2.5.2 Cc ch chuyn mch trong LAN

B chuyn mch cung cp kh nng tng t nh cu ni, nhng c kh

nng thch ng tt hn trong trng hp phi m rng qui m, cng nh trongtrng hp phi ci thin hiu sut vn hnh ca ton mng.

B chuyn kt ni theo on mng hoc thit b thc hin chc nng ca n

bng cch xy dng v duy tr mt c s d liu lu danh sch cc cng v phn

on mng kt ni ti. Khi mt khung tin gi ti, b chuyn mch s kim tra a

ch ch c trong khung tin, sau tm s cng tng ng trong c s d liu

gi khung tin ti ng cng.

Cch thc nhn v chuyn khung tin cho ta 2 ch chuyn mch:

-Chuyn mch lu v chuyn(Store and forward switching)

-Chuyn mch ngay(Cut through switching)

2.2.5.2.1 Chuyn mch lu v chuyn(Store and forward switching)

Cc b chuyn mch lu v chuyn hot ng nh cu ni. Trc ht khi c

khung tin gi ti, b chuyn mch s nhn ton b khung tin, kim tra tnh ton

vn d liu ca khung tin, sau mi chuyn tip khung tin ti cng cn chuyn.

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Khung tin trc ht phi c lu li kim tra tnh ton vn do s c

mt tr nht nh t khi d liu c nhn ti khi d liu c chuyn i.

Vi ch chuyn mch ny, cc khung tin m bo tnh ton vn mi c

chuyn mch, cc khung tin li s khng c chuyn.

2.2.5.2.2 Chuyn mch ngay (Cut through switching)

Cc b chuyn mch ngay hot ng nhanh hn so vi cc b chuyn mch

lu v chuyn. B chuyn mch c a ch ch phn u khung tin ri chuyn

ngay khung tin ti cng tng ng m khng cn kim tra tnh ton vn.

Cc b chuyn mch i mi c kh nng gim st cc cng ca n v quyt

nh s s dng phng php no thch hp nht. Chng c th t ng chuyn

t phng php chuyn ngay sang phng php lu v chuyn nu s li trn

cng vt qua ngng xc nh

Chng 3. Thit k mng LAN

3.1 M hnh c bn

3.1.1 M hnh phn cp

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Hnh 16. M hnh phn cp

Cu trc :

Lp li (Core Layer): y l trc xng sng ca mng (backbone) thng

dng cc b chuyn mch c tc cao ( high-speed switching), thng c cc

c tnh nh tin cy cao, c cng sut d tha, c kh nng t khc phc li,

c kh nng thch nghi cao, p ng nhanh, d qun l, c kh nng lc gi, hay

lc cc tin trnh trong mng.

Lp phn tn (Distribution Layer) : Lp phn tn l ranh gii gia lp truy

nhp v lp li ca mng, lp phn tn thc hin cc chc nng nh m bo gi

d liu n tng phn on mng, m bo an ninh - an ton, phn on mng

theo nhm cng tc, chia min broadcast/multicast, nh tuyn gia cc LAN,

chun mi trng truyn dn, nh tuyn gia cc min, to bin gii min gia

cc min trong nh tuyn tnh v ng, thc hin cc b lc gi (theo a ch,

theo s hiu cng,.....), thc hin cc c ch m bo cht lng dch v.

Lp truy nhp (Access Layer) : Lp truy nhp cung cp cc kh nng truy

nhp cho ngi s dng cc b hay t xa truy nhp vo mng. Thng c thc

hin bng cc b chuyn mch (switch) trong mi trng campus, hay cng ngh

WAN.

nh gi m hnh :

Gi thnh thp.

35 | P a g e

Access

Distribution

core


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D ci t.

D m rng.

D c lp li.

3.1.2 M hnh an ninh- an ton (Secure model)

LAN c lp lm vng m gia mng cng tc vi mng bn ngoi ( LAN

c lp c gi l khu phi qun s hay vng DMZ)

Thit b nh tuyn trong c ci t b lc gi c t gia DMZ v mng

cng tc.

Thit b nh tuyn ngoi c ci b lc c t gia DMZ v mng ngoi.

3.2 Cc yu cu thit k

Yu cu k thut.

Yu cu v hiu nng.

Yu cu v ng dng.

Yu cu v qun l mng.

Yu cu v an ninh-an ton mng. Yu cu rng buc v ti chnh, thi gian thc hin, yu cu v chnh

tr ca d n, xc nh ngun nhn lc, xc nh cc ngun ti nguyn

c v c th ti s dng.

Cc bc thit k

3.3.1 Phn tch yu cu:

-Xc nh mc tiu s dng LAN : Ai s dng LAN v yu cu v dunglng trao d liu, loi hnh dch v, thi gian p ng, Yu cu pht trin

ca LAN trong tng lai; xc nh ch s hu v qun tr LAN.

-Xc nh s lng nt mng hin thi v tng lai (rt ln trn 1000 nt,

va trn 100 nt v nh di 10 nt). Trn c s s lng nt mng, chng ta c

phng thc phn cp, chn k thut chuyn mch, v chn thit b chuyn

mch.

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-Da vo m hnh phng ban phn on vt l m bo hai yu cu an

ninh v m bo cht lng dch v.

-Da vo m hnh tp la chn cng ngh i cp.

-D bo cc yu cu m rng.

3.3.2 La chn phn cng (thit b, cng ngh kt ni,...)

Da trn cc phn tch yu cu v kinh ph d kin cho vic trin khai,

chng ta s la chn nh cung cp thit b tt nht nh l Cisco, Nortel, 3COM,

Intel.... Cc cng ngh tin tin nht ph hp vi iu kin Vit Nam ( kinh t v

k thut) hin c trn th trng, v s c trong tng lai gn.

Cc cng ngh c kh nng m rng.Phn cng chia lm ba phn : H tng kt ni (h thng cp), cc thit b kt

ni (hub, switch, bridge, router), cc thit b x l (cc loi server, cc loi my

in, cc thit b lu d,...).

3.3.2 La chn phn mm :

-La chn h iu hnh Unix ( AIX,OSF, HP, Solaris,....), Linux , Windows

da trn cc yu cu v x l s lng giao dch, p ng thi gian thc, kinh

ph, an ninh an ton.

-La chn cc cng c pht trin phn mm ng dng nh cc phn mm

qun tr c s d liu (Oracle, Informix, SQL,...), cc phn mm portal nh

Websphere,...

-La chn cc phn mm mng nh th in t ( Sendmail, PostOffice,

Netscape,...), Web server ( Apache, IIS,...).

-La chn cc phn mm m bo an ninh an ton mng nh phn mmtng la (PIX, Checkpoint,...), phn mm phng chng vi rt

(VirusWall,NAV,...), phn mm chng t nhp v phn mm qut l hng an

ninh trn mng.

-La chn cc phn mm qun l v qun tr mng.

3.3.3 nh gi kh nng, gi thnh:

-Da vo thng tin c xc nh ca cc hng c uy tn trn th gii.

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-Thc hin th nghim v kim tra trong phng th nghim ca cc chuyn

gia.

-nh gi trn m hnh th nghim.

Gi thnh thp m bo cc ch tiu k thut, cc yu cu ca ng dng, tnh

kh nng m ca h thng.

38 | P a g e


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Chng 4. Hoch nh v lp t

4.1 Xy dng mng LAN trong qui m 1 to nh

Xy dng mng LAN trong to nh iu hnh khng ln, phc v cho cng

tc nghin cu v ging dy.

4.1.1 Trong h thng mng bao gm:

H thng cc thit b chuyn mch (switch c chc nng nh tuyn L3

switch) cung cp nn tng mng cho cc my tnh c th trao i thng tin vi

nhau. Do ton b phn mng xy dng tp trung trong 1 to nh nn h thng cp

truyn dn s s dng bao gm cc cp ng tiu chun UTP CAT5 v cp

quang a mode.Cng ngh mng cc b s dng l Ethernet/Fast

ethernet/Gigabitethernet tng ng tc 10/100/100Mbps chy trn cp UTP

hoc cp quang.

Cc my ch dch v nh c s d liu qun l, ging dy, truyn thng...

Cc my tnh phc v cho cc nghin cu khoa hc: cung cp cc thng tin

v sinh vin, gio vin, cung cp cng c cho cc cn b ging dy.

My tnh phc v ring cho cng tc qun l hnh chnh nhm thc hin

mc tiu tin hc ho qun l hnh chnh.

4.1.2 Phn tch yu cu:

Mng my tnh l mng LAN c bng thng rng khai thc hiu qu

cc ng dng, c s d liu c trng ca t chc, p ng kh nng chy cc

ng dng a phng tin (hnh nh, m thanh) phc v cho cng tc ging dy t

xa.

Mng c xy dng da trn nn tng cng ngh truyn dn tc cao

Ethernet/Fast ethernet/Gigabitethernet, v h thng cp mng xon UTP CAT5

v cp quang a mode.

Mng cn c n nh cao v kh nng d phng m bo cht lng

cho vic truy cp v ng dng d liu quan trng cng nh o to trc tuyn.

Mng c kh nng cung cp vic ging dy t xa trong phm vi t chc nn

cc ng dng phi p ng thi gian thc.

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H thng cp mng cn c thit k m bo p ng cc yu cu v kt

ni tc cao, kh nng d phng cng nh m rng.

Mng cn m bo an ninh an ton cho ton b h thng trc cc truy nhp

tri php t mng bn ngoi.

LAN ny c cu thnh bi cc switch chuyn mch tc cao hn ch ti

thiu xung t d liu truyn ti. Cc switch c kh nng to cc LAN o phn

on mng thnh cc phn nh hn thnh tng phng tng ban. LAN o l cng

ngh dng trong mng ni b cho php s dng cng mt nn tng mng bao

gm nhiu switch c phn chia v mt logic theo cc cng ngh trn switch

thnh cc phn on mng nh khc nhau v c lp hot ng.

Vic phn mng LAN o cho php cc phng ban t chc c cc phn mngmy tnh c lp tin cho vic pht trin cc ng dng ni b cng nh tng

cng tnh bo mt gia cc phn mng my tnh ca cc phng ban khc nhau.

Tuy nhin, LAN o cng cho php qun l tp trung ton b h thng mng my

tnh nht l h thng my tnh my ch thay v pht trin rt nhiu phn mng

mt cch ring r. iu ny to ra mi trng lm vic tp trung cho ngi qun

tr cng nh ct gim cc chi ph do tp trung c cc thit b mng li v my

ch dch v hot ng 24/24 vo mt s phng c iu kin h tng y (inngun n nh, iu ho hot ng tt) thay v nm ri rc trn cc phng ban

khc. Cng ngh mng LAN o gii quyt ng thi c hai bi ton v qun

tr tp trung v ring r cho mng my tnh ca t chc.

Mng m bo kh nng nh tuyn trao i thng tin gia cc phn mng

LAN o khc nhau, cho php cc phn mng khc nhau c th kt ni n nhau

thng qua mi trng mng dng chung. Tuy nhin, do phn cch cc mng

LAN bng switch c tnh nng nh tuyn (hay cn gi l switch c chc nng

layer3) nn cc gi tin boardcasting trn ton mng c hn ch t i v lm cho

bng thng ca mng c s dng hiu qu hn so vi trng hp ton b

mng ca trng xy dng thnh mt mng LAN khng phn cp. Ngoi ra, khi

s dng chc nng nh tuyn cho php ngi qun tr mng c php nh

ngha cc lut hn ch hay cho php cc phn mng c kt ni vi nhau bng

cc b lc (access list) tng cng tnh bo mt cho cc phn mng quan trng

cng nh kh nng qun tr h thng d dng hn.

40 | P a g e


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4.2 Thit k h thng:

4.2.1 H thng chuyn mch v nh tuyn trung tm ca LAN

H thng chuyn mch chnh bao gm cc switch c kh nng s l tc

cao c cu trc phn thnh 2 lp phn tn (distribution) v lp cung cp truy

nhp (access) cho cc u cui my tnh. Switch phn tn l switch tc cao,

bng thng ln c kh nng s l n hng trm triu bit/giy. Switch phn phi

cn c chc nng nh tuyn cho cc phn mng LAN o khc nhau thit lp trn

mng v tng cng bo mt cho cc phn mng ring r. Switch truy cp lm

nhim v cung cp cng cho cc u cui my tnh v tch hp cng truy cp v

tc cao. Cc kt ni gia switch truy cp v switch phn phi l cc kt ni

truyn ti d liu qua li cho cc LAN o nn phi c tc cao 100/1000Mbps.Cc switch truy cp cung cp cc cng truy nhp cho my tnh mng c tc

thp nn cn c cng 10/100Mbps.

H thng switch phn phi theo cu hnh chun bao gm 2 switch c cu

hnh mnh p ng yu cu chuyn mch d liu tc cao v tp trung lu

lng n t cc access switch. Switch phn phi cng m nhn chc nng nh

tuyn. Cu hnh 2 switch phn phi cho php mng li c d phng cao (d

phng 1:1). Tuy nhin trong trng hp mng ban u khng ln v kinh ph hnch vn c th trin khai vi 1 switch phn phi p ng nhng yu cu hot

ng. T chc hon ton c kh nng nng cp ln 2 switch phn phi trong

tng lai do thit k mng cp m bo yu cu trn.

H thng switch truy cp cung cp cho cc my tnh ng kt ni vo mng

d liu. Do phn ln cc giao tip mng cho my tnh u cui cng nh server

hin ti c bng thng 10/100Mbps nn cc switch truy cp cng s dng cng

ngh 10/100Basetx fastEthernet v p ng 1 mc tiu cung cp s lng cng

truy cp ln cho php m rng s lng ngi truy cp mng trong tng lai.

Cc switch truy cp s kt ni vi switch phn phi tp trung v thng qua

switch phn phi vi lm tc v tp trung v lu chuyn qua li lu lng d liu

s gip cho cc my nm trn cc switch khc nhau c th lin lc c vi

nhau. Cc ng kt ni gia switch truy nhp v switch phn phi cn c gi

l cc kt ni ln (up link) v s dng cng ngh fastethernet 100BaseTX c

bng thng 100Mbps.Trong tng lai khi cn nng cp cc kt ni uplink th c

th s dng thay th cng ngh 100BaseTX vi tc Gigabit.

41 | P a g e


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Hnh 17 M hnh thit k

Trong cu hnh v mng my tnh cc b to nh iu hnh c 1 switch phn

phi c chc nng nh tuyn (Layer 3 switch). Switch c tc dng chuyn lu

lng qua li gia cc switch truy cp v 1 nhim v rt quan trng l nh tuyn

gia cc LAN o. Bt k 1 switch truy cp no c kt ni n switch phn

phi bng ng kt ni uplink 100Mbps v kt ni ny m bo cung cp bng

thng cho ton b my tnh kt ni n switch truy cp. Switch phn phi y

l thit b c nhiu cng truy nhp 100Mbps. Cc switch truy nhp cung cp 24

cng 10/100Mbps m bo bng thng ny cho tng my trm. Ton b to nh

s c 14 switch truy cp cung cp s cng ti a cho khong 300 my tnh. Nu

42 | P a g e

My trm

My trm

My trm

My trm

My trm

My trm

Mytrm

My trm

Mng LAN mitrong to nh

Kt ni 100Mbps

Kt ni 10Mbps

My ch quly

My trm

Mng my ch ni b

Switch truy cp

Chc nng layer 3

Chc nng layer 2

My ch c s dliu


41/47


s lng my tnh trong ton b ta nh pht trin ln, cc switch truy cp c th

cm xp trng cung cp s lng cng truy cp nhiu hn hoc cc phng ban

c th cm switch m rng cung cp thm s cng truy cp. Tuy nhin vic

cm thm switch m rng cn tun th qui tc v vic xy dng mng trnh tnhtrnh cm thit b mng (hub, switch) m rng trn lan v lm gim ng k tc

truy cp cc my tnh ca phn mng xa khi tp trung nhiu lu lng ti

nng vo 1 switch truy cp v lm qu ti bng thng uplink ln switch phn

phi.

Cc switch truy cp c chia thnh 2 nhm gi l closet vi mi nhm 7

switch c t ti 2 phng bao gm 1 phng thng tin v mt phng trung tm

iu khin mng trong to nh. Trung tm iu hnh mng cng l ni t cc

my ch ni b v switch phn phi. T cc phng ny c cc phin u cp

UTP v cp c a n cc my tnh c t ri rc trn nhiu phng. Mi 1

nhm switch do cung cp truy cp cho c to nh. Thit k ny cho php cc

switch truy cp cung cp c s cng cho cc thit b my tnh ca cc khoa,

phng ban tho mn iu kin dy cp t mi my tnh ti switch khng vt

qu 100m, y l gii hn di vt l s dng cp mng xon UTP CAT5 hoc

CAT5 vi cng ngh 10/100 fastethernet. Mi 1 switch truy cp c 1 ng kt

ni uplink ln switch.

Mng my ch dch v ni b tch ri trong 1 phn mng LAN cho php

bo mt tt hn v qun tr tp trung.

Trong trng hp cc khoa, phng ban cn pht trin ng dng c th cho

ni b khoa mnh cng c th t my ch tp trung ti trung tm iu hnh

mng ti trung tm iu hnh mng v s dng cng ngh mng LAN o nh

ngha my ch kt ni trong phn mng nh dnh cho khoa, phng, ban .

m bo qun l thit b trung nhng vn mm do trong vic phn chia cp

qun tr 1 cch tng i c lp v ring r.

C th xy dng 1 phn mng tp trung my tnh ti khu my ch trung tm

to iu kin cho cc cn b, gio vin c thit b my tnh thc hin truy

cp mng ly thng tin trong trng hp cn thit.

Khi mng pht trin, tng cng tin cy ca mng li v m rng

nng lc mng, s s dng 2 switch phn phi v mi switch truy cp c kt

43 | P a g e


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ni n 2 switch phn phi bng hai ng uplink. Cc switch phn phi cng s

c kt ni vi nhau theo 1 th tc cho php thay th ln nhau hot ng ca

chc nng nh tuyn trn cc switch.

4.2.2 H thng cp

H thng cp c chia thnh 2 phn. Mi phn ph trch cung cp truy

nhp cho cc my tnh nm trong 1/2 to nh. Do cc switch trong 1 closet t

cng vi switch phn phi ti trung tm iu hnh mng v cc switch trong

closet cn li t trong 1 phng ti trung tm iu hnh mng nn cc cp ni

uplink t cc switch trong closet th 2 sang switch phn phi s dng cc UTP

25 i. Cc cp uplink t cc switch trong closet 1 do nm cng vi switch phn

phi s l cp nhy 4 i. Ti cc phng t cc thit b switch s c cc patchpanel AMT vi 24 cng RJ-45/1 patch panel tp trung u ni cho cp mng.

Cp UTP ni gia my tnh v switch truy cp l cp 4 i cho thng t cc

patch panel AMT ti 1 trong 2 phng t thit b switch n cc outlet ring r

t gn trn tng phng gn ni t cc my tnh ca ngi s dng. Do dy

cp c 4 i nn c th s dng 2 dy tha lm dy d phng.

4.3 Card mng

4.3.1 Vai tr ca card mng

Card ng vai tr ni kt vt l gia cc my tnh v cp mng nhng card

mng c lp vo khe m rng bn trong my tnh v my phc v trn mng.

Sau khi lp card mng, card c ni vi cng card to ni kt vt l tht s

gia my tnh vi nhng my tnh cn li ca mng.

Vai tr ca card mng l:

-Chun b d liu cho cp mng

-Gi d liu n my tnh khc

-Kim sot lung d liu gia my tnh v h thng cp

Card mng cng nhn d liu ca cp v chuyn dch thnh byte CPU

my tnh c th hiu c. Card cha phn cng v phn sn (tc cc th tc

phn mm ngn c lu tr trong b nh ch c) thc hin cc chc nng

logical link control v media access control.

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4.3.2 Cc cu trc ca card mng

Kin trc chun cng nghip ISA (Industry Standard Architecture): l kin

trc dng trong my tnh IBM PC/XT, PC/AT v mi bn sao.ISA cho php gn

thm nhiu b thch ng cho h thng bng cch chn cc card b sung cc khem rng.

Kin trc chun cng nghip m rng EISA (Extended Industry Standard

Architecture) l tiu chun bus do 1 tp on chnh hng cng nghip my tnh

AST Research, INC ..Compaq, ... EISA cung cp mt ng truyn 32 bit v duy

tr kh nng tng thch vi ISA trong khi cung cp nhng c tnh b xung do

IBM a ra trong bus kin trc vi knh ca hng.

Kin trc vi knh MCA (Micro Channel Architechture) IBM a ra tiuchun ny nm 1988. MCA khng tng thch v phng din in v vt l vi

bus ISA. MCA khng hot ng nh bus ISA 16 bit hoc nh bus 32 bit v c

th iu khin c lp bng b s l chnh a bus.

B kt ni ngoi vi PCI (Peripear Component Interconnect) y l bus cc

b 32 bit dng cho h my Pentium.Kin trc bus PCI hin nay p ng nhu cu

tnh nng cm v chy. Mc tiu ca tnh nng ny l cho php thc hin cc

thay i v cu hnh my m khng cn s can thip ca ngi s dng

4.4 Qun l v cp pht a ch IP

Mng my tnh th vin l mng my tnh dng ring, do vy s c nh

a ch IP trong di a ch IP dng ring qui nh ti RFC1918 (bao gm cc a

ch t 10.0.0.0 n 10.255.255.255,172.16.0.0 n 172.31.255.255 v a ch

192.168.0.0 n 192.168.255.255). S lng my tnh cho 1 segment mng ng

nht c tnh bng s lng my tnh d phng s c trong to nh (khong vi

chc my). C th gn cho 2 segment my tnh bng cc lp class C a ch IP tclass C 192.168.0.0 n 192.168.255.0 .

H thng cc my ch s nm trong phn mng ring v c a ch IP gn

cho phn lp a ch 172.18.0.0 c th truy cp vo Internet mt s cc my

ch cn c chc nng che du a ch nh Firewall hay Proxy v cc my ch

ny cn c a ch IP tht. Cc my tnh trong mng s dng a ch ca cc my

ch khi kt ni vo Internet. Nu cc my ch cn cung cp thng tin cho ngi

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s dng dng Internet th cn phi nh a ch IP cho cc my ch ny l a ch

do IANA cung cp.

kt ni n cc phn mng my tnh ca trng v mng quc gia, cn

tun th 1 qui nh nh a ch mt cch cht ch khi s dng trng vnga ch mng dng ring. C th s dng cc k thut chuyn i a ch NAT

trnh xung t a ch khi kt ni 2 mng.

d dng cho vic qun tr h thng cc thit b switch vi kh nng h tr

DHCP v cng vi vic thit lp my ch DHCP, cc my tnh trm trong to

nh s c cp pht a ch IP t ng v tin cy.

4.5 Xy dng h thng tng la kt ni mng vi Internet

Mng my tnh cc b s c kt ni vi mng Internet thng qua Firewall.

Firewall s lm nhim v ngn chn v bo mt cc my tnh thuc phn mng

ni b vi mng Internet bn ngoi. Khi giao tip mng firewall s kt ni vi

phn mng bn trong v 1 giao tip mng s kt ni vi phn mng Internet.

Hnh 18 M hnh tng la kt ni mng LAN vi Internet

46 | P a g e

My trm

My trm

Mng my ch ni

Mng LAN mitrong to nh

My trm

My trmMy trm

My trm

My trm

Mytrm

My trm

My ch quly My ch c s dliu

Switch truycp

My trmMy trm

Bnh

tuyn

Phnmng

truy nhp

internet

Accessserver

Thit b Firewall

Nh cung cp

Dch vInternet

Mytrm


45/47


KT LUN

Bo co trn y l mt s kin ca em v cc loi mng thng dng s

dng trong vn phng, cng ty, hoc mt ta nh, mng s dng trong mt khuvc v mng trong thng mi in t. C th ni, l kt qu ca vic vn

dng nhng kin thc c trang b nh trng vo i sng v cc lnh vc

khc.

Trong bo co ny, em t ra mt s khi nin c bn nhm hon thin

hn cc khi nim v h thng mng thng dng nht. Em hy vng v tin tng

rng l nhng khi nim ng n c th p dng cho tt c cc lnh vc khc

trong h thng cng ngh thng tin ni chung v cc ngnh lin quan n mngmy tnh ni ring.

Trong sut qu trnh thc hin lm bo co, em nhn c s gip ch

bo v hng dn tn tnh ca cc thy gio, thy gip em hon thnh tt bi

bo co ny.

XIN TRN THNH CM N.

Ngi thc hin n.

V VN THOI

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Hng pht trin

Nh trn ni mng my tnh kt ni qua ng in thoi tr

nn thng dng vi tt c mi ngi trn th gii cng nh vit nam. Kt ni

mng khng dy ang dn tr thnh mt su th hin i, thi thng bn cnhcc loi hnh kt ni mng tuyn thng dng dy cp. Cht lng tin cy, hot

ng n nh, th tc ci t n gin, gi c phi chng l nhng yu t c

trng chng t kt ni khng dy sn sng p ng mi nhu cu trao i

thng tin khc nhau t sn sut, kinh doanh n nhu cu gii tr .v.v. .Thit lp

mng khng dy khng tn km thi gian, cng sc v phc tp nh cc h thng

mng truyn thng khc, i khi khng qu mt gi ng h lao ng l c th

hnh thnh mt h thng mng khng dy. Thc t cho thy, a s cc s c, trc

trc xy ra trong h thng mng khng dy l do phn mm iu khin thit b c

li.

u im ln nht ca mng khng dy l cho php ngi s dng c

th truy cp vo bt k lc no v bt k ni u trn tri t.

Chnh v l m mng khng dy s l t tng tip theo m em s

nghin cu.

48 | P a g e


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Ti liu tham kho:

Mng cn bn - NXB thng k - bin dch: VN - GUIDE

Mng my tnh v cc h thng m - Nguyn Thc Hi

http://quantrimang.com.vn/hoi-dap/cau-hoi/hoc-tap/Tim-hieu-va-thiet-ke-

mang-lan-trong-mot-toa-nha-3283.aspx

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