manglan

MC LC Module 1: KIN THC C BN V MNG, MNG LAN, GIAO THC TCP/IP V A CH IPI. Gii thiu chung v mng:................................................................................2 1. S hnh thnh ca mng my tnh......................................................................... 2 2. Mng my tnh l g? ............................................................................................ 2 3. Cc mc tiu ca vic to nn mng my tnh....................................... ............... 3 4. Phn loi mng my tnh....................................................................................... 3 4.1 Phn loi mng theo khong cch a l : ....................................................... 3 4.2 Phn loi theo k thut chuyn mch: ............................................................. 4 4.3 Phn loi theo kin trc mng s dng............................................. ............... 5 4.4 Phn loi theo h iu hng mng ................................................................... 5 5. Cc mng my tnh thng dng nht .................................................................... 6 5.1 Mng cc b LAN (Local Network Area)......................................................... 6 5.2 Mng din rng WAN (Wide Area Network) vi kt ni LAN to LAN ............. 6 5.3 Lin mng INTERNET...................................................................................... 6 5.4 Mng INTRANET ............................................................................................. 6

II. Mng cc b - LAN (Local Area Network): ..............................................81. Khi nim .............................................................................................................. 8 2. Cc c tnh k thut ca LAN ............................................................................. 8 3. Cc topo mng ...................................................................................................... 9 3.1. nh ngha Topo mng .................................................................................... 9 3.2. Mng hnh sao .................................... ........................................................... 10 3.3. Mng trc tuyn tnh (Bus): .......................................................................... 11 3.4. Mng vng ..................................................................................................... 11 3.5. Kt ni hn hp ............................................................................................. 12 4. Cc loi cp truyn v hng dn cch bm cp mng cc loi......................... 12 4.1. Cc loi cp truyn ....................................................................................... 12 4.2. Cc thit b kt ni....................................................................... .................. 16 4.3. Nhng iu cn bit v qu trnh thit lp mng LAN: ................................ 21

III. Cu hnh TCP/IP trn my tnh:.............................................................281. Cu hnh TCP/IP ng: ....................................................................................... 28 2. Cu hnh tnh: ...................................................................................................... 30 3. Kim tra kt ni: ................................................................................................. 33

IV. X l li trong mng LAN........................................................................341. Kim tra li cp v thit b.................................................................................. 34 2. X l cc li ca TCP/IP trong LAN................................................ .................. 35 2.1 M ca s du nhc dng lnh ..................................................................... 35

Ti liu tp hun K thut MegaVNN Module 1: Gii thiu chung v mng, mng LAN, TCP/IP

2.2. Kim tra cu hnh TCP/IP: ........................................................................... 36

I. Gii thiu chung v mng:Trong lch s pht trin ca loi ngi, th k XX c nh du bi cuc cch mng v cng ngh thng tin, bao gm cc vn : thu thp, x l v phn phi thng tin. iu c bit l khi kh nng thu thp, x l v phn phi thng tin ca con ngi tng ln, th nhu cu ca chnh con ngi v vic x l thng tin mt cch tinh vi, phc tp li tng nhanh hn na. Ngy nay my tnh in t c s dng ph bin, vic kt ni my tnh trong cc mng l xu hng tt yu, khng ch trong lnh vc nghin cu thun tu m c trong hu ht mi lnh vc hot ng ca con ngi. 1. S hnh thnh ca mng my tnh Giai on u (khong 1960) h thng my tnh c tp trung ho cao , thng th cc my tnh c tp trung trong mt hoc mt vi vn phng. Ch c cc c quan, cng ty c kh nng ti chnh kh ln mi c th trang b mt vi my tnh in t. Trong h thng my tnh tp trung ny thng ch s dng mt my tnh ln (Mainframe) v nhiu trm u cui (Terminal) ni vi n. Trong h thng ny, my Mainframe phi x l tt c mi cng vic, cc trm lm vic ch n thun l cc mn hnh v bn phm n khng c b nh, khng c cc a, khng c kh nng tnh ton v x l d liu. N ch c chc nng gi i cc yu cu v nhn v cc kt qu t my tnh trung tm ri hin th n trn mn hnh, do ta gi cc trm lm vic ny l trm cm (Dumb Terminal). Nhc im ca h thng tp trung ny l: Cc my trm phi ph thuc hon ton vo my tnh trung tm do h thng ny khng c coi l mng my tnh 2. Mng my tnh l g? Mng my tnh l h thng cc my tnh c lp c kt ni vi nhau thng qua cc ng truyn vt l v tun theo cc quy c truyn thng no . Khi nim my tnh c lp y c ngha l cc my tnh khng c my no c kh nng khi ng hoc nh ch mt my khc. Cc ng truyn vt l c hiu l cc mi trng truyn tn hiu vt l (c th l hu tuyn hoc v tuyn nh dy dn, tia Laser, sng ngn, v tinh nhn to...). 2


Cc quy c truyn thng chnh l c s cc my tnh c th "ni chuyn" c vi nhau v l mt yu t quan trng hng u khi ni v cng ngh mng my tnh. 3. Cc mc tiu ca vic to nn mng my tnh S dng chung ti nguyn: chng trnh, d liu, thit b.... Tng tin cy ca h thng thng tin: Nu mt my tnh hay mt n v

d liu no trong mng b hng th lun c th s dng mt my tnh khc hay mt bn sao ca n v d liu. Tit kim chi ph. Qun l tp trung To ra mi trng truyn thng mnh gia nhiu ngi s dng trn phm

vi a l rng. Mc tiu ny ngy cng tr nn quan trng. 4. Phn loi mng my tnh C nhiu cch phn loi mng khc nhau tu thuc vo yu t chnh c chn dng lm ch tiu phn loi, thng thng ngi ta phn loi mng theo cc tiu ch nh sau : Khong cch a l ca mng K thut chuyn mch m mng p dng Kin trc mng H iu hnh mng s dng ... 4.1 Phn loi mng theo khong cch a l : Nu ly khong cch a l lm yu t phn loi mng th ta c mng cc b, mng th, mng din rng, mng ton cu. Mng cc b ( LAN - Local Area Network ) : l mng c ci t trong phm vi tng i nh hp nh trong mt to nh, mt x nghip...vi khong cch ln nht gia cc my tnh trn mng trong vng vi km tr li. Mng th ( MAN - Metropolitan Area Network ) : l mng c ci t trong phm vi mt th, mt trung tm vn ho x hi, c bn knh ti a khong 100 km tr li. Mng din rng ( WAN - Wide Area Network ) : l mng c din tch bao ph rng ln, phm vi ca mng c th vt bin gii quc gia thm ch c lc a.

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Mng ton cu ( GAN - Global Area Network ) : l mng c phm vi tri rng ton cu. 4.2 Phn loi theo k thut chuyn mch: Nu ly k thut chuyn mch lm yu t chnh phn loi s c: mng chuyn mch knh, mng chuyn mch thng bo v mng chuyn mch gi. Mch chuyn mch knh (circuit switched network) : Khi c hai thc th cn truyn thng vi nhau th gia chng s thit lp mt knh c nh v duy tr kt ni cho ti khi hai bn ngt lin lc. Cc d liu ch truyn i theo con ng c nh . Nhc im ca chuyn mch knh l tiu tn thi gian thit lp knh truyn c nh v hiu sut s dng mng khng cao. Mng chuyn mch thng bo (message switched network) : Thng bo l mt n v d liu ca ngi s dng c khun dng c quy nh trc. Mi thng bo c cha cc thng tin iu khin trong ch r ch cn truyn ti ca thng bo. Cn c vo thng tin iu khin ny m mi nt trung gian c th chuyn thng bo ti nt k tip trn con ng dn ti ch ca thng bo. Nh vy mi nt cn phi lu gi tm thi c thng tin iu khin trn thng bo, nu thy thng bo khng gi cho mnh th tip tc chuyn tip thng bo i. Tu vo iu kin ca mng m thng bo c th c chuyn i theo nhiu con ng khc nhau. u im ca phng php ny l : Hiu sut s dng ng truyn cao v khng b chim dng c quyn m Mi nt mng c th lu tr thng tin tm thi sau mi chuyn thng C th iu khin vic truyn tin bng cch sp xp u tin cho cc C th tng hiu sut x dng gii thng ca mng bng cch gn a ch c phn chia gia nhiu thc th truyn thng. bo i, do c th iu chnh lm gim tnh trng tc nghn trn mng. thng bo. qung b (broadcast addressing) gi thng bo ng thi ti nhiu ch.

Nhc im ca phng php ny l: Khng hn ch c kch thc ca thng bo dn n ph tn lu gi tm thi cao v nh hng n thi gian tr li yu cu ca cc trm .

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Mng chuyn mch gi (packet switched network): y mi thng bo c chia ra thnh nhiu gi nh hn c gi l cc gi tin (packet) c khun dng qui nh trc. Mi gi tin cng cha cc thng tin iu khin, trong c a ch ngun (ngi gi) v a ch ch (ngi nhn) ca gi tin. Cc gi tin ca cng mt thng bo c th c gi i qua mng ti ch theo nhiu con ng khc nhau. Phng php chuyn mch thng bo v 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 (cc nt chuyn mch) c th x l ton b gi tin trong b nh m khng phi lu gi tm thi trn a. Bi vy nn mng chuyn mch gi truyn d liu hiu qu hn so vi mng chuyn mch thng bo. Tch hp hai k thut chuyn mch knh v chuyn mch gi vo trong mt mng thng nht c mng tch hp s (ISDN Integated Services Digital Network). 4.3 Phn loi theo kin trc mng s dng Kin trc ca mng bao gm hai vn : hnh trng mng (Network topology) v giao thc mng (Network protocol) Hnh trng mng: Cch kt ni cc my tnh vi nhau v mt hnh hc m ta gi l t p ca mng Giao thc mng: Tp hp cc quy c truyn thng gia cc thc th truyn thng m ta gi l giao thc (hay nghi thc) ca mng Khi phn loi theo topo mng ngi ta thng c phn loi thnh: mng hnh sao, trn, tuyn tnh Phn loi theo giao thc m mng s dng ngi ta phn loi thnh mng : TCPIP, mng NETBIOS . .. Tuy nhin cch phn loi trn khng ph bin v ch p dng cho cc mng cc b 4.4 Phn loi theo h iu hng mng Nu phn loi theo h iu hnh mng ngi ta chia ra theo m hnh mng ngang hng, mng khch/ch hoc phn loi theo tn h iu hnh m mng s dng: Windows NT, Unix, Novell . . . Tuy nhin trong thc t ngui ta thng ch phn loi theo hai tiu ch u tin.

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5. Cc mng my tnh thng dng nht 5.1 Mng cc b LAN (Local Network Area) Mt mng cc b l s kt ni mt nhm my tnh v cc thit b kt ni mng c lp t trn mt phm v a l gii hn, thng trong mt to nh hoc mt khu cng s no . Mng c tc cao, c xu hng s dng rng ri nht. Cc thng tin v mng LAN c gii thiu chi tit ti mc II. 5.2 Mng din rng WAN (Wide Area Network) vi kt ni LAN to LAN Mng din rng l s kt ni ca cc mng LAN, mng din rng c th tri trn phm vi mt vng, quc gia hoc c mt lc a thm ch trn phm vi ton cu. Mng c tc truyn d liu khng cao, phm vi a l khng gii hn

Hnh 1.1:

M hnh kt ni mng WAN

5.3 Lin mng INTERNET Vi s pht trin nhanh chng ca cng ngh l s ra i ca lin mng INTERNET. Mng Internet l s hu ca nhn loi, l s kt hp ca rt nhiu mng d liu khc chy trn nn tng giao thc TCP/IP. 5.4 Mng INTRANET

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Thc s l mt mng INTERNET thu nh vo trong mt c quan/cng ty/t chc hay mt b/ngnh, gii hn phm vi ngi s dng, c s dng cc cng ngh kim sot truy cp v bo mt thng tin . c pht trin t cc mng LAN, WAN dng cng ngh INTERNET

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II. Mng cc b - LAN (Local Area Network):1. Khi nim Mng cc b LAN (Local Area Network) l h thng 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 khu vc a l nh nh mt tng ca ta nh, hoc mt ta nh Tn gi mng cc b c xem xt t quy m ca mng. Tuy nhin, khng phi l c tnh duy nht ca mng cc b nhng trn thc t, quy m ca mng quyt nh nhiu c tnh v cng ngh ca mng. Sau y l mt s c im ca mng cc b: c im ca mng cc b: - Mng cc b c quy m nh, thng l bn knh di vi km. c im ny cho php khng cn dng cc thit b dn ng vi cc mi lin h phc tp - Mng cc b thng l s hu ca mt t chc. iu ny dng nh c v t quan trng nhng trn thc t l iu kh quan trng vic qun l mng c hiu qu. Mng cc b c tc cao v t li. Trn mng rng tc ni chung ch t vi Kbit/s. Cn tc thng thng trn mng cc b l 10, 100 Mb/s v ti nay vi Gigabit Ethernet, tc trn mng cc b c th t 1Gb/s. Xc xut li rt thp. 2. Cc c tnh k thut ca LAN - ng truyn: L thnh phn quan trng ca mt mng my tnh, l phng tin dng truyn cc tn hiu in t gia cc my tnh. Cc tn hiu in t chnh l cc thng tin, d liu c biu th di dng cc xung nh phn (ON_OFF), mi tn hiu truyn gia cc my tnh vi nhau u thuc sng in t, tu theo tn s m ta c th dng cc ng truyn vt l khc nhau. Cc my tnh c kt ni vi nhau bi cc loi cp truyn: cp ng trc, cp xon i... - Chuyn mch: L c trng k thut chuyn tn hiu gia cc nt trong mng, cc nt mng c chc nng hng thng tin ti ch no trong mng. Trong mng ni b, phn chuyn mch c thc hin thng qua cc thit b chuyn mch nh HUB, Switch... - Kin trc mng: Kin trc mng my tnh (network architecture) th hin cch ni cc my tnh vi nhau v tp hp cc quy tc, quy c m tt c cc thc th tham gia truyn thng trn mng phi tun theo m bo cho mng hot ng tt. 8


Khi ni n kin trc ca mng ngi ta mun ni ti hai vn l topo mng (Network topology) v giao thc mng (Network protocol). + Network Topology: Cch kt ni cc my tnh vi nhau v mt hnh hc m ta gi l Topo ca mng. Cc hnh trng mng c bn l: hnh sao, hnh bus, hnh vng. + Network Protocol: Tp hp cc quy c truyn thng gia cc thc th truyn thng m ta gi l giao thc (hay nghi thc) ca mng Cc giao thc thng gp nht l: TCP/IP, NETBIOS, IPX/SPX,... - H iu hnh mng: H iu hnh mng l mt phn mm h thng c cc chc nng sau: + Qun l ti nguyn ca h thng, cc ti nguyn ny gm: Ti nguyn thng tin (v phng din lu tr) hay ni mt cch n gin l qun l tp. Cc cng vic v lu tr tp, tm kim, xa, copy, nhm, t cc thuc tnh u thuc nhm cng vic ny. Ti nguyn thit b: iu phi vic s dng CPU, cc thit b ngoi vi... ti u ha vic s dng. + Qun l ngi dng v cc cng vic trn h thng. H iu hnh m bo giao tip gia ngi s dng, chng trnh ng dng vi thit b ca h thng. + Cung cp cc tin ch cho vic khai thc h thng thun li (v d Format a, sao chp tp v th mc, in n chung ...) Cc h iu hnh mng thng dng nht hin nay l: WindowsNT, Windows9X, Windows 2000, Unix, Novell. 3. Cc topo mng 3.1. nh ngha Topo mng Cch kt ni cc my tnh vi nhau v mt hnh hc m ta gi l topo ca mng. C hai kiu ni mng ch yu l: Ni kiu im - im (point - to - point). Ni kiu im - nhiu im (point - to - multipoint hay broadcast).

Theo kiu im - im, cc ng truyn ni tng cp nt vi nhau v mi nt u c trch nhim lu gi tm thi sau chuyn tip d liu i cho ti ch. Do cch lm vic nh vy nn mng kiu ny cn c gi l mng "lu v chuyn tip" (store and forward). 9


Theo kiu im - nhiu im, tt c cc nt phn chia nhau mt ng truyn vt l chung. D liu gi i t mt nt no s c tip nhn bi tt c cc nt cn li trn mng, bi vy cn ch ra a ch ch ca d liu cn c vo cc nt kim tra xem d liu c phi gi cho mnh khng. Phn bit kiu topo ca mng cc b v kiu topo ca mng din rng. Topo ca mng din rng thng thng l ni n s lin kt gia cc mng cc b thng qua cc b dn ng (router). i vi mng din rng topo ca mng l hnh trng hnh hc ca cc b dn ng v cc knh vin thng cn khi ni ti topo ca mng cc b ngi ta ni n s lin kt ca chnh cc my tnh. 3.2. Mng hnh sao

Hub

Hnh 1.2:

Kt ni hnh sao

Mng hnh sao c tt c cc trm c kt ni vi mt thit b trung tm c nhim v nhn tn hiu t cc trm v chuyn n trm ch. Tu theo yu cu truyn thng trn mng m thit b trung tm c th l b chuyn mch (switch), b chn ng (router) hoc l b phn knh (hub). Vai tr ca thit b trung tm ny l thc hin vic thit lp cc lin kt im-im (point-to-point) gia cc trm. u im ca topo mng hnh sao: Thit lp mng n gin, d dng cu hnh li mng (v d thm, bt cc trm), d dng kim sot v khc phc s c, tn dng c ti a tc truyn ca ng truyn vt l. Nhc im ca topo mng hnh sao: di ng truyn ni mt trm vi thit b trung tm b hn ch (trong vng 100m, vi cng ngh hin nay).

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3.3. Mng trc tuyn tnh (Bus):


Hnh 1.3:

Kt ni kiu bus

Trong mng trc tt c cc trm phn chia mt ng truyn chung (bus). ng truyn chnh c gii hn hai u bng hai u ni c bit gi l terminator. Mi trm c ni vi trc chnh qua mt u ni ch T (T-connector) hoc mt thit b thu pht (transceiver). Khi mt trm truyn d liu tn hiu c qung b trn c hai chiu ca bus, tc l mi trm cn li u c th thu c tn hiu trc tip. i vi cc bus mt chiu th tn hiu ch i v mt pha, lc cc terminator phi c thit k sao cho cc tn hiu phi c di li trn bus cho cc trm trn mng u c th thu nhn c tn hiu . Nh vy vi topo mng trc d liu c truyn theo cc lin kt im-a im (point-to-multipoint) hay qung b (broadcast). u im : D thit k, chi ph thp Nhc im: Tnh n nh km, ch mt nt mng hng l ton b mng b ngng hot ng. 3.4. Mng vng

Hnh 1.4:

Kt ni kiu vng

Trn mng hnh vng tn hiu c truyn i trn vng theo mt chiu duy nht. Mi trm ca mng c ni vi vng qua mt b chuyn tip (repeater) c

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nhim v nhn tn hiu ri chuyn tip n trm k tip trn vng. Nh vy tn hiu c lu chuyn trn vng theo mt chui lin tip cc lin kt im-im gia cc repeater do cn c giao thc iu khin vic cp pht quyn c truyn d liu trn vng mng cho trm c nhu cu. tng tin cy ca mng ta c th lp t thm cc vng d phng, nu vng chnh c s c th vng ph s c s dng. Mng hnh vng c u nhc im tng t mng hnh sao, tuy nhin mng hnh vng i hi giao thc truy nhp mng phc tp hn mng hnh sao. 3.5. Kt ni hn hp L s phi hp cc kiu kt ni khc nhau v d hnh cy l cu trc phn tng ca kiu hnh sao hay cc HUB c th c ni vi nhau theo kiu bus cn t cc HUB ni vi cc my theo hnh sao.HUBHb u

Hb u

B chuyn i cp

Hnh 1.5:

Mt kt ni hn hp

4. Cc loi cp truyn v hng dn cch bm cp mng cc loi 4.1. Cc loi cp truyn Hin ti phn ln cc khch hng dng cp i dy xon kt ni cc thit b trong mng LAN ca h. Cp i dy xon l cp gm hai dy ng xon trnh gy nhiu cho cc i dy khc, c th ko di ti vi km m khng cn khuych i. Gii tn trn cp dy xon t khong 3004000Hz, tc truyn t vi Kbps n vi Mbps. Cp xon c hai loi:

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Loi c bc kim loi tng cng chng nhiu gi l cp STP ( Shield Twisted Pair). Loi ny trong v bc kim c th c nhiu i dy. V l thuyt th tc truyn c th t 500 Mb/s nhng thc t thp hn rt nhiu (ch t 155 Mb/s vi cp di 100 m) Loi khng bc kim gi l UTP (UnShield Twisted Pair), cht lng km hn STP nhng gi thnh rt r. Cp UTP c chia lm 5 hng tu theo tc truyn. Cp loi 3 dng cho in thoi. Cp loi 5 c th truyn vi tc 100Mb/s rt hay dng trong cc mng cc b v va r va tin s dng. Cp ny c 4 i dy xon nm trong cng mt v bc

Hnh 1.6:

Cp UTP 5

Hnh trn l cp xon i CAT 5, loi cp ph bin nht dng trong mng LAN u khch hng hin nay. Mi si cp c 8 li v c chia ra lm 4 cp. Mi cp gm mt dy mu v mt dy khoang mu c xon li vi nhau. m bo cp hot ng tin cy, khng nn tho xon chng nhiu hn mc cn thit (6mm). Ch 2 trong 4 cp dy c s dng truyn dn tn hiu trong mng LAN l cp mu da cam v cp mu xanh lc. Hai cp cn li mu nu v xanh lam khng c s dng. S chn c s dng bm trong u RJ45.

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Hnh 1.7:

Hai chun bm cp T-568B V T-568A

C 2 chun bm dy cho loi cp ny l chun T-568A v chun T-568B. Vi mi loi c mt cch sp xp cp vo u RJ45 khc nhau. Vi chun T-568B, cp cam v lc c a vo chn 1,2 v 3,6 mt cch tng ng trn u RJ45. Chun T568A o cp cam va cp lc cho cp lc a vo chn 1,2 cn cp cam a vo chn 3,6. iu ny lm cho cp lam v cp cam nm trn 4 chn gia, ph hp vi chun kt ni ca cng ty in thoi. Do chun T-568A c coi nh chun chnh v hay c s dng cn chun T-568B ch l chun thay th. S chn ca chun T-568B: Pin Color Pair Description 2 2 3 1 1 3 4 4 TxData + TxData RcData + Unused Unused RcData Unused Unused

1 White/Orange 2 Orange

3 White/Green 4 5 6 Blue White/Blue Green

7 White/Brown 8 Brown

S chn ca chun T-568A: Pin Color Pair Description 14


1 White/Green 2 Green

3 3 2 1 1 2 4 4

RcData + RcData TxData + Unused Unused TxData Unused Unused

3 White/Orange 4 5 6 Blue White/Blue Orange

7 White/Brown 8 Brown

Cp thng v cp cho: Ni chung trong hu ht trng hp u s dng cp thng. Cp thng l cp c cc chn ca u ny c kt ni n chn u kia mt cch tng ng. V d: Chn 1 ca u ny ni vi chn 1 ca u kiaTa ch s dng cp cho khi kt ni 2 thit b trc tip vi nhau m khng qua Hub hay switch. Cp cho s u cho chn 1,2 v chn 3,6 2 u RJ 45 vi nhau 2 giao din ging nhau c th giao tip c vi nhau. Crossover Cable RJ-45 PIN RJ-45 PIN 1 Rx+ 2 Rc3 Tx+ 6 Tx3 Tx+ 6 Tx1 Rc+ 2 RcStraight Through Cable RJ-45 PIN RJ-45 PIN 1 Tx+ 2 Tx3 Rc+ 6 Rc1 Rc+ 2 Rc3 Tx+ 6 Tx-

Nh ni trn, cp cho thng c s dng kt ni 2 thit b c giao din ging nhau nh: Hub vi Hub, Tranceiver vi Tranceiver, DNI vi DNI card hay Tranceiver vi DNI card.

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Kt ni Hub vi Hub:


Kt ni Hub vi Tranceiver hay DNI card:

Kt ni Tranceiver vi DNI card:

4.2. Cc thit b kt ni h thng mng lm vic trn tru, hiu qu v kh nng kt ni ti nhng h thng mng khc i hi phi s dng nhng thit b mng chuyn dng. Nhng thit b mng ny rt a dng v phong ph v chng loi nhng u da trn nhng thit b c bn l Repeater, Hub, Switch, Router v Gateway.

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Repeater


Hnh 1.8:

Thit b Repeater

Trong mt mng LAN, gii hn ca cp mng l 100m (cho loi cp mng CAT 5 UTP l cp c dng ph bin nht), bi tn hiu b suy hao trn ng truyn nn khng th i xa hn. V vy, c th kt ni cc thit b xa hn, mng cn cc thit b khuch i v nh thi li tn hiu, gip tn hiu c th truyn dn i xa hn gii hn ny. Repeater l mt thit b lp 1 (Physical Layer) trong m hnh OSI. Repeater c vai tr khuch i tn hiu vt l u vo v cung cp nng lng cho tn hiu u ra c th n c nhng chng ng tip theo trong mng. in tn, in thoi, truyn thng tin qua si quang v cc nhu cu truyn tn hiu i xa u cn s dng Repeater. Hub

Hnh 1.9:

Thit b Hub

Hub c coi l mt Repeater c nhiu cng. Mt Hub c t 4 n 24 cng v c th cn nhiu hn. Trong phn ln cc trng hp, Hub c s dng trong cc mng 10BASE-T hay 100BASE-T. Khi cu hnh mng l hnh sao (Star topology), Hub ng vai tr l trung tm ca mng. Vi mt Hub, khi thng tin vo t mt cng v s c a n tt c cc cng khc. 17


Hub c 2 loi l Active Hub v Smart Hub. Active Hub l loi Hub c dng ph bin, cn c cp ngun khi hot ng, c s dng khuch i tn hiu n v cho tn hiu ra nhng cng cn li, m bo mc tn hiu cn thit. Smart Hub (Intelligent Hub) c chc nng tng t nh Active Hub, nhng c tch hp thm chip c kh nng t ng d li - rt hu ch trong trng hp d tm v pht hin li trong mng. Bridge

Hnh 1.10:

Thit b Bridge

Bridge l thit b mng thuc lp 2 ca m hnh OSI (Data Link Layer). Bridge c s dng ghp ni 2 mng to thnh mt mng ln duy nht. Bridge c s dng ph bin lm cu ni gia hai mng Ethernet. Bridge quan st cc gi tin (packet) trn mi mng. Khi thy mt gi tin t mt my tnh thuc mng ny chuyn ti mt my tnh trn mng khc, Bridge s sao chp v gi gi tin ny ti mng ch. u im ca Bridge l hot ng trong sut, cc my tnh thuc cc mng khc nhau vn c th gi cc thng tin vi nhau n gin m khng cn bit c s "can thip" ca Bridge. Mt Bridge c th x l c nhiu lu thng trn mng nh Novell, Banyan... cng nh l a ch IP cng mt lc. Nhc im ca Bridge l ch kt ni nhng mng cng loi v s dng Bridge cho nhng mng hot ng nhanh s kh khn nu chng khng nm gn nhau v mt vt l.

18

Switch


Hnh 1.11:

Thit b Switch

Switch i khi c m t nh l mt Bridge c nhiu cng. Trong khi mt Bridge ch c 2 cng lin kt c 2 segment mng vi nhau, th Switch li c kh nng kt ni c nhiu segment li vi nhau tu thuc vo s cng (port) trn Switch. Cng ging nh Bridge, Switch cng "hc" thng tin ca mng thng qua cc gi tin (packet) m n nhn c t cc my trong mng. Switch s dng cc thng tin ny xy dng ln bng Switch, bng ny cung cp thng tin gip cc gi thng tin n ng a ch. Ngy nay, trong cc giao tip d liu, Switch thng c 2 chc nng chnh l chuyn cc khung d liu t ngun n ch, v xy dng cc bng Switch. Switch hot ng tc cao hn nhiu so vi Repeater v c th cung cp nhiu chc nng hn nh kh nng to mng LAN o (VLAN). Router

Hnh 1.12:

Thit b Router

Router l thit b mng lp 3 ca m hnh OSI (Network Layer). Router kt ni hai hay nhiu mng IP vi nhau. Cc my tnh trn mng phi "nhn thc" c s tham gia ca mt router, nhng i vi cc mng IP th mt trong nhng quy tc ca IP l mi my tnh kt ni mng u c th giao tip c vi router.

19


u im ca Router: V mt vt l, Router c th kt ni vi cc loi mng khc li vi nhau, t nhng Ethernet cc b tc cao cho n ng dy in thoi ng di c tc chm. Nhc im ca Router: Router chm hn Bridge v chng i hi nhiu tnh ton hn tm ra cch dn ng cho cc gi tin, c bit khi cc mng kt ni vi nhau khng cng tc . Mt mng hot ng nhanh c th pht cc gi tin nhanh hn nhiu so vi mt mng chm v c th gy ra s nghn mng. Do , Router c th yu cu my tnh gi cc gi tin n chm hn. Mt vn khc l cc Router c c im chuyn bit theo giao thc - tc l, cch mt my tnh kt ni mng giao tip vi mt router IP th s khc bit vi cch n giao tip vi mt router Novell hay DECnet. Hin nay vn ny c gii quyt bi mt mng bit ng dn ca mi loi mng c bit n. Tt c cc router thng mi u c th x l nhiu loi giao thc, thng vi chi ph ph thm cho mi giao thc. Gateway

Hnh 1.13:

Thit b Gateway

Gateway cho php ni ghp hai loi giao thc vi nhau. V d: mng ca bn s dng giao thc IP v mng ca ai s dng giao thc IPX, Novell, DECnet, SNA... hoc mt giao thc no th Gateway s chuyn i t loi giao thc ny sang loi khc. Qua Gateway, cc my tnh trong cc mng s dng cc giao thc khc nhau c th d dng "ni chuyn" c vi nhau. Gateway khng ch phn bit cc giao thc m cn cn c th phn bit ng dng nh cch bn chuyn th in t t mng ny sang mng khc, chuyn i mt phin lm vic t xa...

20


4.3. Nhng iu cn bit v qu trnh thit lp mng LAN: Cc mng LAN tr nn thng dng v n cho php cc ngi dng (users) dng chung cc 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 l c lp vi nhau, b hn ch bi s lng cc chng trnh tin ch. Sau khi kt ni mng r rng hiu qu ca chng tng ln gp bi. Cc thnh phn thng thng trn mt mng cc b gm c: - Cc my ch cung cp dch v (server) - Cc my trm cho ngi lm vic (workstation) - ng truyn (cp ni) - Card giao tip gia my tnh v ng truyn (network interface card) - Cc thit b ni (connection device) Nh vy vic thit k mt mng my tnh cc b chnh l vic la chn v lp t cc cu hnh thch hp cho mi thnh phn ca mng. Tu thuc vo mc ch, tnh cht v phm vi s dng m ngi thit k xy dng ln cu hnh mng LAN thch hp.

Hnh 1.14:

Cu hnh mng LAN

Nhn chung, yu t quyt nh s dng loi cp no l ph thuc vo yu cu tc truyn tin, khong cch t cc thit b, yu cu an ton thng tin v cu hnh ca mng,....V d mng Ethernet 10 Base-T l mng dng knh truyn bng tn c

21


bn vi thng lng 10 Mbit/s theo tiu chun quc t ISO/IEC 8802.3 ni bng i dy cp xon khng bc kim (UTP) trong Topo hnh sao. Vic kt ni cc my tnh vi mt dy cp c dng nh mt phng tin truyn tin chung cho tt c cc my tnh. Cng vic kt ni vt l vo mng c thc hin bng cch cm mt card giao tip mng NIC (Network Interface Card) vo trong my tnh v ni n vi cp mng. Sau khi kt ni vt l hon tt, qun l vic truyn tin gia cc trm trn mng tu thuc vo phn mm mng. u ni ca NIC vi dy cp c nhiu loi (ph thuc vo cp mng), hin nay c mt s NIC c hai hoc ba loi u ni. Chun dng cho NIC l NE2000 do hng Novell v Eagle dng ch to cc loi NIC ca mnh. Nu mt NIC tng thch vi chun NE2000 th ta c th dng n cho nhiu loi mng. NIC cng c cc loi khc nhau m bo s tng thch vi my tnh 8-bit v 16-bit. Mng LAN thng bao gm mt hoc mt s my ch (file server, host), cn gi l my phc v v mt s my tnh khc gi l trm lm vic (Workstations) hoc cn gi l nt mng (Network node) - mt hoc mt s my tnh cng ni vo mt thit b nt. My ch thng l my c b x l (CPU) tc cao, b nh (RAM) v cng (HDD) ln. Trong mt trm m cc phng tin c dng chung, th khi mt trm mun gi thng ip cho trm khc, n dng mt phn mm trong trm lm vic t thng ip vo "phong b", phong b ny gi l gi (packet), bao gm d liu thng ip c bao bc gia tn hiu u v tn hiu cui ( l nhng thng tin c bit) v s dng phn mm mng chuyn gi n trm ch. NIC s chuyn gi tn hiu vo mng LAN, gi tn hiu c truyn i nh mt dng cc bit d liu th hin bng cc bin thin tn hiu in. Khi n chy trong cp dng chung, mi trm gn vi cp u nhn c tn hiu ny, NIC mi trm s kim tra a ch ch trong tn hiu u ca gi xc nh ng a ch n, khi gi tn hiu i ti trm c a ch cn n, ch trm s sao gi tn hiu ri ly d liu ra khi phong b v a vo my tnh.

22


III. Giao thc TCP/IP v a ch IPNgi ta thng dng t TCP/IP ch mt s cc khi nim v tng khc nhau. Thng dng nht l n m t hai giao thc lin lc dng truyn d liu. TCP tc l Transmission Control Protocol (Giao thc iu khin truyn dn) v IP c ngha l Internet Protocol (Giao thc Intermet). Khi nim TCP/IP khng ch b gii hn hai giao thc ny. Thng th TCP/IP c dng ch mt nhm cc giao thc c lin quan n TCP v IP nh UDP (User Datagram Protocol Giao thc gi d liu ngi s dng), FTP (File Transfer Protocol Giao thc truyn tp), TELNET (Terminal Emulation Protocol Giao thc m phng u cui), v.v... Cc mng dng TCP/IP gi l cc TCP/IP Internet. V ngun gc, TCP/IP c thit k trong ht nhn ca h iu hnh BSD UNIX 4.2. y l mt phin bn mnh ca UNIX, v cng l mt l do cho s ph bin rng ri ca TCP/IP. Hu ht cc trng i hc v nhiu t chc nghin cu dng BSD UNIX. Ngy nay, a s cc my tnh trn Internet chy cc phin bn l con chu trc tip ca BSD UNIX. Thm na, nhiu bn thng mi ca UNIX nh SunOS ca SUN hay Ultrix ca Digital u pht sinh t bn BSD UNIX 4.2. S thit lp TCP/IP trong UNIX System V cng b nh hng rt ln ca BSD UNIX, cng nh th i vi TCP/IP ca Novell trn DOS (cc sn phm LANWorkplace) v NetWare 3.x/4.x.

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1. Cc tng giao thc TCP/IP


Application Presentation Session

Application layer Program Program

Transport

Transport layer

TCP

UDP

Network

Network layer

ICMP

IP

IGMP

DataLink

Link layer ARP

Hardware Interface

RARP

Physical

Hnh 1.15:

Cc tng ca TCP/IP so vi 7 tng tng ng ca OSI

TCP: Transmission Control Protocol (Giao thc iu khin truyn dn) - Th tc lin lc tng giao vn ca TCP/IP. TCP c nhim v m bo lin lc thng sut v tnh ng n ca d liu gia hai u ca kt ni, da trn cc gi tin IP. UDP: User Datagram Protocol (Giao thc gi d liu ngi dng) - Th tc lin kt tng giao vn ca TCP/IP. Khc vi TCP, UDP khng m bo kh nng thng sut ca d liu, cng khng c ch sa li. B li, UDP cho tc truyn d liu cao hn TCP. IP: Internet Protocol (Giao thc Internet) - L giao thc tng th 3 ca TCP/IP, n c trch nhim vn chuyn cc datagram qua mng Internet. ICMP: Internet Control Message Protocol (Giao thc bn tin iu khin Internet) - Th tc truyn cc thng tin iu khin trn mng TCP/IP. IGMP: Internet Group Management Protocol (Giao thc qun l nhm Internet) - L mt giao thc dng iu khin cc thng tin ca nhm.

24


ARP: Address Resolution Protocol (Giao thc phn gii a ch) - L giao thc tng lin kt d liu. Chc nng ca n l tm a ch vt l ng vi mt a ch IP no . Mun vy n thc hin broadcasting trn mng, v my trm no c a ch IP trng vi a ch IP ang c hi s tr li thng tin v a ch vt l ca n. RARP: Reverse Address Resolution Protocol (Giao thc phn gii a ch ngc) - L mt giao thc cho php mt my tnh tm ra a ch IP ca n bng cch broadcasting li yu cu trn ton mng. 2. Phng php nh a ch trong TCP/IP c th thc hin truyn tin gia cc my trn mng, mi my tnh trn mng TCP/IP cn phi c mt a ch xc nh gi l a ch IP. Hin ti chng ta ang s dng a ch IPv4 (IP Address Version 4). a ch th h mi ca Internet - IPv6 (IP Address Version 6) c Nhm c trch K thut IETF (Internet Engineering Task Force) ca Hip hi Internet xut thc hin k tha trn cu trc v t chc ca IPv4. a ch IPv4 c to bi mt s 32 bit. Cc a ch IP c chia ra lm hai phn, mt phn nhn dng mng (NET ID) v mt phn xc nh host (HOST ID). Cc lp mng (Network class) xc nh s bit c dnh cho mi phn mng v phn host. C nm lp mng l A, B, C, D, E, trong ba lp u l c dng cho mc ch thng thng, cn hai lp D v E c dnh cho nhng mc ch c bit v tng lai. Hnh v sau cho thy cu trc ca mt a ch IPv4: Cu trc a ch IP Network ID Host ID

Bng phn lp a ch IP: Lp mng A B C D E S mng 126 16.382 2.097.150 Khng phn Khng phn S Host trong mng 16.777.214 65.534 254

25


Khng phi tt c cc s hiu mng (NETWORK ID) u c th dng c. Mt s a ch c dnh cho nhng mc ch c bit. V d nh mng 127.0.0.0 dng cho a ch loopback (quay vng)

Lp A c bit 31 lun bng 0 cn bit t 24-30 nh a ch mng, bit t 0 23 nh a ch host. Theo cu trc ny lp A cho php nh danh ti 126 mng (s dng byte u tin), vi ti a 16 triu host (3 byte cn li, 24 bits) cho mi mng. Lp ny c dng cho cc mng c s trm cc ln. Ti sao li c 126 mng trong khi dng 8 bits? L do u tin, 127.x (01111111) dng cho a ch loopback, th 2 l bit u tin ca byte u tin bao gi cng l 0, 1111111(127). Dng a ch lp A (network number. host.host.host). Nu dng k php thp phn cho php 1 n 126 cho vng u, 1 n 255 cho cc vng cn li. Lp B c bit 31 lun bng 1 v bit 30 lun bng 0, bit t 16-29 dng nh a ch mng cn bit t 0-15 dng nh a ch host. Nh vy, lp B cho php nh danh ti 16384 mng (10111111.11111111.host.host), vi ti a 65535 host trn mi mng. Dng ca lp B (network number. Network number.host.host). Nu dng k php thp phn cho php 128 n 191 cho vng u, 1 n 255 cho cc vng cn lic s mng v s host va phi. Lp C c bit 31 lun bng 1, bit 30 lun bng 1 cn bit 29 lun bng 0. Bit t 8-28 dng nh a ch mng cn t 0-7 dng nh a ch host. Nh vy, lp C cho php nh danh ti 2.097.150 mng v ti a 254 host cho mi mng. Lp ny c dng cho cc mng c t trm. Lp C s dng 3 bytes u nh danh a ch mng (110xxxxx). Dng ca lp C (network number.

26


Network number.Network number.host). Nu dng dng k php thp phn cho php 129 n 233 cho vng u v t 1 n 255 cho cc vng cn li. Lp D dng gi IP datagram ti mt nhm cc host trn mt mng. Tt c cc s ln hn 233 trong trng u l thuc lp D Lp E d phng dng trong tng lai

Nh vy a ch mng cho lp: A: t 1 n 126 cho vng u tin, 127 dng cho a ch loopback, B t 128.1.0.0 n 191.255.0.0, C t 192.1.0.0 n 233.255.255.0 cho bn c d hiu, ngi ta thng biu din a ch IP di dng s nguyn chm thp phn. Mt a ch IP khi s c biu din bi 4 s thp phn c gi tr t 0 n 255 v c phn cch nhau bi du chm (.). Mi gi tr thp phn biu din 8 bit trong a ch IP. V d mt a ch IP ca my ch Web ti VDC l 203.162.0.11; Trn mng Internet, vic qun l v phn phi a ch IP l do Trung tm Thng tin mng (NIC - Network Information Center) m nhim. Vi s bng n ca s my tnh kt ni vo mng Internet, a ch IP tr thnh mt ti nguyn cn kit, ngi ta phi xy dng nhiu cng ngh khc phc tnh hnh ny. V d nh cng ngh cp pht a ch IP ng nh BOOTP hay DHCP (Dynamic Host Configuration Protocol Giao thc cu hnh a ch ng). Khi s dng cng ngh ny th khng nht thit mi my trn mng u phi c mt a ch IP nh trc m n s c my ch cp cho mt a ch IP khi thc hin kt ni.

27


III. Cu hnh TCP/IP trn my tnh:1. Cu hnh TCP/IP ng: Bc 1: Kch chut tri vo Start/ Setting/ Network Connection/ Local Area Connection

Hnh 1.16:

M Local Area Connection

Bc 2: Kch vo Properties

28


Hnh 1.17:

Chn Properties

Bc 3: Kch p vo Internet Protcol (TCP/IP)

Hnh 1.18:

V tr ca Internet Protocol

-

Bc 4: nh du (Tch) vo Obtain an IP address automatically Obtain DNS server address automatically

29


Hnh 1.19:

t a ch IP v DNS ng

Bc 5: Trong du nhc dng lnh nh: ipconfig v kim tra li a ch IP

nhn c trn my tnh.

Hnh 1.20:

Kim tra a ch IP bng lnh Ping

2. Cu hnh tnh: Bc 1: Kch chut tri vo Start/ Setting/ Network Connection/ Local Area Connection

30


Hnh 1.21:

M LocalArea Connection

Bc 2: Kch vo Properties

Hnh 1.22:

Chn Properties ca Local Area Connection

Bc 3: Kch p vo Internet Protcol (TCP/IP)

31


Hnh 1.23:

V tr ca Internet Protocol

-

Bc 4: Tch vo Use the following IP address Use the following DNS Server addresses

nh vo a ch IP, subnet mask, default gateway, v DNS server vo nhng tng ng.

Hnh 1.24:

t cc thng s v IP v DNS

32


Bc 5: Trong du nhc dng lnh nh: ipconfig v kim tra li a ch IP

nhn c trn my tnh.

Hnh 1.25:

Kim tra IP ca my

3. Kim tra kt ni: S dng lnh ping kim tra kt ni t my tnh n mt my tnh no . Mu cu lnh nh hnh di

Hnh 1.26:

Kt qu lnh Ping n mt s a ch my tnh khc

33


IV. X l li trong mng LAN1. Kim tra li cp v thit b Buc 1: Kim tra n tn hiu trn cc mng (NIC v hub/switch)

Hnh 1.27:

Kim tra n tn hiu

Bc 2: Nu n sng trn card mng v Switch: kt ni tt, xem li Driver card mng v cc giao thc (protocols)

34


Hnh 1.28:

Kim tra Driver card mng v cc giao thc

Bc 3 : Nu n tn hiu trn card mng v Switch khng sng, thc hin cc + Cm u mng (u cm vo Switch) sang cng khc + Di chuyn card mng sang khe cm m rng khc + Thay th card mng + Thay Switch khc + Cm u dy mng sang my tnh khc + Thay th dy mng

bc sau:

Bc 4 : Kim tra li kt ni 2. X l cc li ca TCP/IP trong LAN 2.1 M ca s du nhc dng lnh x l li lin quan n TCP/IP s c rt nhiu ln chng ta cn dng n dng

lnh. Dng lnh c vit trong ca s du nhc dng lnh. m ca s du nhc dng lnh ta nhp chut tri vo Start | Run, nh cmd trong hin ra v nhp OK.

35


m ca s dng lnh trong Windows 95,98 hay Me, nhp vo Start | Run, nh command vo hp thoi v nhp vo OK. nh mi lnh mt dng v n Enter thc thi dng lnh . ng ca s ny ra nh lnh exit. 2.2. Kim tra cu hnh TCP/IP:

Hnh 1.29:

Kim tra cu hnh TCP/IP

kim tra cu hnh TCP/IP ca mi my tnh trn mng LAN ta m th mc Network Connection, nhp chut phi vo LAN connection v nhp vo Status | Support | Details.

Hnh 1.30:

Th IP Configuration

Trong Windows 95, 98 hay Me, nhp vo Start | Run, nh winipcf vo hp thoi v nhp OK. Chn Lan adapter t menu v nh More Info. Ta cng c th xem cu hnh TCP/IP t du nhc dng lnh. Cch ny c bit thun tin nu my tnh c nhiu card mng. S dng ln ipconfig /all, lnh ny cng c th s dng c trong Windows 95. Thng tin hin ra t lnh ny c th kh di nn tt hn nn vit n vo 1 tp d kim tra hn. Cu lnh nh sau: 36


ipconfig /all >ipconfig.txt y l thng tin cu hnh TCP/IP t mt my tnh Windows sau khi nh lnh trn: C:\Documents and Settings\Trinh Minh Tri>ipconfig /all Windows IP Configuration Host Name . . . . . . . . . . . . : tritm Primary Dns Suffix . . . . . . . : Node Type . . . . . . . . . . . . : Unknown IP Routing Enabled. . . . . . . . : No WINS Proxy Enabled. . . . . . . . : No DNS Suffix Search List. . . . . . : netscreen-208 Ethernet adapter INT: Connection-specific DNS Suffix . : netscreen-208 Description . . . . . . . . . . . : Realtek RTL8139 Family PCI Fast Ethe rnet NIC Physical Address. . . . . . . . . : 00-13-D3-62-2C-97 Dhcp Enabled. . . . . . . . . . . : Yes Autoconfiguration Enabled . . . . : Yes IP Address. . . . . . . . . . . . : 192.168.92.78 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . : 192.168.92.1 DHCP Server . . . . . . . . . . . : 192.168.92.1 DNS Servers . . . . . . . . . . . : 203.162.0.11 203.162.4.1 Lease Obtained. . . . . . . . . . : Friday, May 16, 2008 2:08:11 PM Lease Expires . . . . . . . . . . : Friday, May 16, 2008 10:08:11 PM M t cu hnh TCP/IP: IP Address: a ch IP duy nht c a vo card mng. Nu my tnh c nhiu card mng s c cu hnh mt a ch IP cho mi ci. V mi a ch IP phi c mt n mng con khc nhau.

37


Subnet mask: S dng theo cp vi a ch IP xc nh mng con cha a ch IP ca card mng ny. ngha ca mt n mng con mc n gin nht l: Giao tip ch c th thc hin c gia 2 card mng nu n thuc cng mng con Default gateway: y l a ch IP ca 1 my tnh hay router trong mt mng LAN gip cho my tnh bit cch giao tip vi cc mng khng xut hin trong my tnh. DHCP Server: Nu card mng c cu hnh nhn a ch IP ng, y l a ch ca server m cung cp a ch IP ny. y c th l ISP hay ICS hay router cng. DNS Server: a ch IP ca mt hay nhiu my tnh phc v phn gii tn min. My ch tn min bin dch tn trn Internet (like www.practicallynetworked.com) thnh a ch IP tng ng (like 63.146.109.227). a ch 169.254.x.x: Nu mt my tnh nhn c a ch 169.254.x.x, iu ny ch ra rng: My tnh ny c cu hnh nhn a ch IP ng N khng tm thy my ch DHCP trn mng nhn a ch IP Windows t ng cp cho n mt a ch IP trong di a ch Ip ring. PING:

Hnh 1.31:

Kim tra kt ni bng lnh Ping

Lnh ping l cng c c bn kim tra kt ni TCP/IP. N gi mt gi tin c bit (ICMP Echo) n mt a ch IP c th v ch tr li. Nu mi th lm vic tt p, s c reply quay tr li. Nu khng, s xut hin dng thng bo li. Di y l nhng thng bo li ta thng gp: Request timed out: a ch IP hp l nhng khng c tr li t my ch. Nu a ch IP nm trong cng mng LAN, nguyn nhn ch yu l do Firewall chn lnh ping. Unknown host hay Ping request could not find host. Tn my tnh khng tn ti trn mng LAN. Kim tra li chc chn rng NetBios over TCP/IP c enable. 38


Destination host unreachable: a ch IP khng nm trn mng LAN v khng tm c a ch default gateway. C th do khng c default gateway trn mng hoc a ch ny sai hay n khng hot ng. Ping mng LAN: Di y l cc lnh ping c s dng x l nhng li thng hay xy ra trong mng LAN. x l li kt ni trong mng LAN, ta hay s dng cc lnh ping ny. Cc lnh ny c sp xp thc hin mt cch tun t t u n cui. Khng nn thc hin lnh sau khi lnh trc y cha c thc hin thnh cng. V d: - My tnh c kim tra c tn l WinXP v a ch IP: 192.168.1.101 - C mt my tnh khc trn mng c t tn l Win98 vi a ch IP 192.168.1.123 Lnh ping 127.0.0.1 ping localhost ping 192.168.1.101 ping winxp ping 192.168.1.123 a ch my ch Loopback address Loopback name a ch IP ca chnh n Tn ca chnh n ngha nu ping li Ci t TCP/IP li Ci t TCP/IP li Ci t TCP/IP li Ci t TCP/IP li

a ch IP ca my tnh khc Trnh iu khin card mng (driver) li. Cng c th do card mng li

ping win98 Ping Internet:

Tn ca my tnh khc

Phn gii tn NetBios li

Ta c th dng lnh ping kim tra vn i vi truy nhp mng Internet. nh nhng lnh ny theo th t nh ch ra di v ng i n lnh sau khi m lnh trc y cha cho kt qu tt. S dng Default gateway v DNS Server c c t lnh ipconfig /all.

Command ping w.x.y.z

Target Default Gateway

What Ping Failure Indicates Default Gateway down

39


ping w.x.y.z ping w.x.y.z

DNS Server Web site IP address

DNS Server down Internet service provider or web site down

ping www.something. com

Web site name

DNS Server down or web site down

40