Tiu Lun Mng My Tnh

Tiu Lun Mng My Tnh Thc hin :Dng Quang Hin Ti: Thit k mng LAN

I. L THUYT:
1. Cu trc topo ca mng
Cu trc topo (network topology) ca mng LAN l kin trc hnh hc th hin cch b tr cc ng dy cp, sp 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 tuyn, dng vng cng vi nhng cu trc kt hp ca chng. 1.1 Mng hnh sao (Star topology) Mng hnh sao bao gm mt b kt ni trung tm v cc nt. Cc nt ny l cc trm u v cui, cc my tnh v cc thit b khc ca mng. B ni trung tm ca mng iu phi mi hot ng trong mng. Mng hnh sao cho php kt ni cc my tnh v mt b trung tm (Hub) bng cp, gii php ny cho php ni trc tip my tnh vi Hub khng cn thng qua trc Bus, trnh c cc yu t gy ngng tr mng.

Hnh II.1: Cu trc mng hnh sao M hnh kt ni mng hnh sao ngy nay tr nn ht sc ph bin. Vi vic s dng cc b tp trung hoc chuyn mch, cu trc mng hnh sao c th c m rng mng bng cch t chc nhiu mc phn cp, do vy d dng trong vic qun l v vn hnh.

* Nhng u im ca mng hnh sao - Hot ng theo nguyn l ni song song nn 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 thut ton iu khin n nh
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Tiu Lun Mng My Tnh

- Mng c th d dng m rng hoc thu hp * Nhng nhc im ca mng hnh sao - Kh nng m rng mng hon ton ph thuc vo kh nng ca thit b - 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 , khong cch t my trung tm rt hn ch (100 m) 1.2 Mng hnh tuyn Bus (Bus topology) Thc hin theo cch b tr hnh lang, cc my tnh v cc thit b khc cc nt mng u c ni 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. Pha hai u dy cp c bt bi mt thit b gi l terminator. Cc tn hiu v d liu khi truyn i dy cp u mang theo a ch ca ni n.

Hnh II. 2: M hnh mng hnh tuyn * Nhng u im ca mng hnh tuyn - Loi hnh mng ny dng dy t nht, d lp t, gi r. * Nhng nhc im ca mng hnh tuyn - S n tc giao thng khi di chuyn d liu vi dung lng ln. - Khi c s hng hc mt b phn no th rt kh pht hin - Ngng trn ng dy sa cha th phi ngng ton b h thng nn cu trc ny ngy nay t c s dng. 1.3 Mng dng vng (Ring topology) Mng dng ny, c b tr theo dng xoay vng, ng dy cp c thit k lm thnh mt vng kho kn, tn hiu c chy theo mt chiu no . Cc nt truyn tn hiu cho nhau mi thi im ch c mt nt m thi. D liu truyn i phi km theo mt a ch c th ca mi trm tip nhn.

Tiu Lun Mng My Tnh

* u im ca mng dng vng - Mng dng vng c thun li l n c th m rng mng ra xa hn, tng ng dy cn thit t hn so vi hai kiu trn. - Mi trm c th t c tc ti a khi truy nhp. * Nhc im ca mng dng vng - ng dy phi khp kn, nu b ngt mt thi im no d th ton h thng cng b ngng.

Hnh II. 3: M hnh mng dng vng 1.4 Mng dng kt hp Kt hp hnh sao v tuyn (Star/ Bus topology) . Cu hnh mng dng ny c b phn tch tn hiu (Spiter) gi vai tr thit b trung tm, ht hng dy cp mng c th chn hoc Ring topology hoc Linear Bus topology. Li im ca cu hnh ny l mng c th gm nhiu nhm lm vic cch xa nhau, ARCNE l mng dng kt hp Star/ Bus Topology . Cu hnh dng ny a li s uyn chuyn trong vic b tr cc ng dy tng thch d dng vi bt c to nh no. Kt hp hnh sao v vng (Star/ Ring topology). Cu hnh dng kt hp Star/ Ring topology), c mt th bi lin lc (Token) c chuyn vng quanh mt ci Hub trung tm. Mi trm lm vic (Workstation) c ni vi Hub l cu ni gia cc trm lm vic v tng khong cch cn thit.

2. Cc Phng php truy nhp ng truyn 2.1 GIAO THC CSMA/CD (carrier Sense Multiple Access with Collision Detection)
Giao thc ny thng c dng cho mng c cu trc hnh tuyn, cc my trm cng chia s mt knh truyn thng 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 trm c truyn d liu m thi, trc khi truyn d liu, mi trm phi lng nghe ng truyn chc chn rng ng truyn ang ri (carrier Sense). Nu gp ng truyn ri mi c truyn.
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Tiu Lun Mng My Tnh

Trong trng hp hai trm thc hin vic truyn d liu ng thi, lc ny kh nng xy ra xung t d liu s l rt cao. Cc trm tham gia phi pht hin c s xung t v thng bo ti cc trm khc gy ra xung t (Collision Dection), ng thi cc trm phi ngng thm nhp truyn d liu ngay, ch i ln sau trong khong thi gian ngu nhin no ri mi tip tc truyn tip. Khi lu lng cc gi d liu cn di chuyn trn mng qu cao, th vic xung t c th xy ra vi s lng ln dn n lm chm tc truyn thng tin ca h thng. 2.2 GIAO THC TRUYN TH BI Giao thc ny thng c dng trong cc mng LAN c cu trc dng vng s dng k thut chuyn th bi (token) cp pht quyn truy nhp ng truyn d liu i. Th bi y l mt n v d liu c bit, c kch thc v ni dung (gm cc thng tin iu khin ) c quy nh ring cho mi giao thc. Trong ng dy cp lin tc c mt th bi chy quanh trong mng. Phn d liu ca th bi c mt bt biu din trng thi s dng ca n (Bn hoc ri). Trong th bi c cha mt a ch ch v mng dng xoay vng th trt t ca s truyn th bi tng ng vi trt t vt l ca trm xung quanh vng. 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 bn, nn gi d liu c km theo a ch ni nhn vo th bi v truyn i theo chiu ca vng. th bi lc ny tr thnh khung mang d liu. Trm ch sau khi nhn khung mang d liu ny s copy d liu vo b m ri tip tc truyn khung theo vng nhng thm mt thng tin xc nhn. Trm ngun nhn li khung ca mnh (theo vng) nhn ng, ri bt bn thnh bt ri v truyn th bi i. V th bi chy vng quanh trong mng kn v c mt th nn vic ng d liu khng th xy ra. Do vy hiu sut truyn d liu ca mng khng thay i, trong cc giao thc ny cn gii quyt hai vn c th dn n ph v h thng. Mt l vic mt th bi lm cho trn vng khng cn th bi lu chuyn na. Hai l mt th bi tun th ng s phn chia ca mi trng mng, hot ng da vo s xoay vng ti cc trm. Vic truyn th bi s khng thc hin c nu vic xoay vng b t on. Giao thc phi cha cc th tc kim tra th bi cho php khi phc li th bi b mt hoc thay th trng thi ca th bi v cung cp cc phng tin sa i logic (thm vo, bt i hoc nh li trt t ca cc trm). 2.3 GIAO THC FDDL
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Tiu Lun Mng My Tnh

FDDL l k thut dng cc mng c cu trc vng, chuyn th bi tc cao bng phng tin cp si quang. FDDL s dng c ch chuyn th bi trong vng trn khp kn. Lu thng trn mng FDDL bao gm 2 lung ging nhau theo hai hng ngc nhau. FDDL thng c s dng vi hai mng trc trn nhng mng LAN cng sut thp c th ni vo. Cc mng LAN i hi tc truyn d liu cao v di bng thng ln cng c th s dng FDDL.

Hnh II. 4: Cu trc mng dng vng ca FDDL

3. Phn don mng LAN

3.1 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 th repeater cho php m rng min xung t.

Hnh II. 5: Kt ni mng Ethernet 10 Base T s dng Hub H thng mng 10 Base T s dng Hub nh l mt b repeater nhiu cng. Cc my trm cng ni mt Hub s thuc cng mt min xung t. Gi s 8 trm ni cng mt Hub 10 Base T tc 10Mb/s, v ti mt thi im ch c mt trm c truyn khung nn bng thng trung bnh mi trm c c l :

Tiu Lun Mng My Tnh

10 Mb/s : 8 trm=1,25 Mbps /1 trm. Hnh sau minh ho min xung t v min qung b khi s dng repeater:

Hnh II. 6: Min xung t v min qung b khi phn on mng bng Repeater Mt iu cn ch khi s dng repeater m rng mng th khong cch xa nht gia 2 trm s b hn ch. Trong hot ng ca Ethernet trong cng mt min xung t, gi tr slotTime s quy nh vic kt ni cc thit b, vic s dng nhiu repeater lm tng gi tr tr truyn khung vt qu gi tr cho php gy ra hot ng khng ng trong mng.

Hnh II. 7: Quy nh vic s dng Repeater lin kt mng

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Tiu Lun Mng My Tnh

3.2. PHN ON MNG BNG CU NI (BRIGE) Cu ni hot ng tng 2 trong m hnh OSI, n c kh nng kim tra phn a ch MAC trong khung v da vo a ch ngun, a ch ch n s 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.

Hnh II.8: Vic truyn tin din ra bn A khng din ra bn B Khc vi trng hp s dng repeater trn, bng thng lc ny ch b chia s trong tng min xung t, mi my tnh trm c s dng nhiu bng thng hn, li ch khc ca vic s dng cu ni l ta c hai min xung t ring bit nn mi min c ring gi tr slottime do vy c th m rng ti a cho tng min

Hnh II.9: Min xung t v min qung b vi vic s dng Bridge Tuy nhin vic s dng cu ni b gii hn bi quy tc 80/20, theo quy tc ny th cu ni ch hot ng hiu qu khi ch c 20 % ti ca phn on i qua cu, 80% l ti trng ni b phn on.

Tiu Lun Mng My Tnh

Hnh II.10: Quy tc 80/20 i vi vic s dng Bridge 3.3 PHN ON MNG BNG ROUTER Router hot ng tng 3 trong m hnh OSI, n c kh nng kim tra header ca gi IP nn a ra quyt nh, n v d liu m cc b nh tuyn thao tc l cc b nh tuyn ng thi to ra cc min xung t v min qung b ring bit

Hnh II. 11: Phn on mng bng Router

3.4 PHN ON MNG BNG B CHUYN MCH B chuyn mch l thit b phc tp nhiu cng cho php cu hnh theonhiu cch khc nhau. C th cu hnh cho n tr thnh nhiu cu o nh sau:

Hnh II. 12: C th cu hnh b chuyn mch thnh nhiu cu hnh o

Tiu Lun Mng My Tnh

Bng tng kt thc hin phn on mng bng cc thit b kt ni khc nhau Thit b Repeater Bridge Router Switch Min xung t Mt Nhiu Nhiu Nhiu Min qung b Mt Mt Nhiu Mt hoc Nhiu

4. Cc ch chuyn mch
4.1 CHUYN MCH LU V CHUYN 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 ca d liu ca khung tin, sau mi chuyn tip khung tin ti cng cn chuyn. 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 t phn on mng ny n phn on mng khc. 4.2 CHUYN MCH NGAY 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. Khung tin c chuyn ngay thm ch trc khi b chuyn mch nhn dng bt d liu. Khung tin i ra khi b chuyn mch trc khi n c nhn cc b chuyn mch i mi c kh nng gim st cc cng ca n v quyt nh s s dng phng php chuyn ngay sang phng php lu v chuyn nu s li trnc cng vt qu mt ngng xc nh.

II THC HNH TO MNG LAN O

Thit lp mng LAN n gin

Tiu Lun Mng My Tnh

Cch thit lp mang Lan trong gia nh 1. Kt ni router n card mng ca tng my: Thao tc ny thc hin kh n gin, bn ch vic s dng mt si cp vi u ni RJ-45 c bm thng (straight) v kt ni dy dn t cngca card mng vo mt trong cc cng pha sau ca router. 2. nh a ch IP cho cc my tnh trong mng a ch IP ny s gip router xc nh c v tr ca cc my trong mng. - nh nh a ch IP cho my tnh, vo menu Start > Control panel > Network Connections. Ti y, bn bm phi vo kt ni mng chn Properties. Ti giao din Local Area Conection Properties, bn di chuyn vt sng xung mc Internet Protocal (TCP/IP), bm Properties v tin hnh nh a ch IP cho my tnh(cc gi tr IP ca mng ni b thng l: 192.168.1.x). Bn thit lp gi tr 192.168.1.2cho my u tin v tng dn cho cc my tip theo (ch vic t a ch ny phi trnh trng vi a ch ca router, xem phn thng s nytrn thit b km theo). -Ngoi ra, nu mun cc my tnh trong mng kt ni trc tip qua router truy cp Internet (theo hnh thc mng ngang hng peer-to-peer) th bn cn cu hnh thm mc Default Gateway. 3. Thit lp kt ni Qu trnh ny c chia thnh hai bc nh: kim tra ban u v kim tra khi kt ni. Kim tra ban u: qutrnh ny gip bn nhn din c tnh trng ca mng hin ti trckhi thit lp ni kt. kim tra vic trao i thng tin gia cc mytrong mng c thng sut vi nhau cha, t menu Start > Run, bn g Cmd. Trn mn hnh xut hin bn hy g lnh: ping <tn my> (hoc a ch IP) n n-1 my tnh cn li. Bn s nhn kt qu tr v c dng Request time out, iu ny cho thy ta ch mi nh a ch IP m cha thit lp kt ni cho chng. thit lp kt ni mng cho cc my tnh qua router ny, bn hy khi ng My Network Place trn mn hnh desktop, sau bm vodng ch Setup a home or small office nm bn tri thanh tc v. Khi mn hnh hin th xut hin, chng trnh s thng bo s dng thit b router kt ni, bn hy ng vi xclp ny bng cch bm Next. Tip theo, hy t tn my (Computer name) v t tn cho Workgroup( c th chia s d liu, cc my tnh phi c tn Workgroup gingnhau). Khi router s np cc thng tin cn thit v yu cu bn khi ng li my Khi khi ng xong, bn hy ln lt chy tin ch ny (My Network Place) cho cc my
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cn li trong mng. kim tra thao tc cui cng khi ni kt xong, mt ln na bn hy g lnh ping <tn my> n cc my cn li trong mng. Nu thy c kt qu Reply tr v l cc my tnh trong mng thng sut v bn c th chia s d liu.

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