MMT DeCuong Final

8/8/2019 MMT DeCuong Final

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P N CNG MNG MY TNH

Cu 1:t vai tr l ngi thit k mng cc b cho mt n v (cng ty, trng hc,

c quan hnh chnh, ...) c kt ni internet, em hy trnh by s thit k

mng v lit k cc thit b cn s dng.

V d: Gi s trng hc c ba ta nh, mi nh cch nhau n 1000 mt, mi

ta nh 3 tng c 15 phng lm vic, mi phng c ti a 5 my tnh v mt

my in. Em c trch nhim xy dng mng cc b cho trng. Hy vit mt bntrnh by s thit k mng v lit k km m t cc thit b cn s dng (dy

truyn, b kt ni, NIC, ...)

1. S thit k mng:- Mi ta nh 3 tng c 15 phng mi tng c 5 phng. Mi phng c ti a5 my tnh v mt my in Mi tng c gn 30 thit b c th cn ni mng,

nn switch cn dng phi l switch 32 cng.- Chng ta c th dng s gm 9 switch v 1 router kt ni vi cc switchng thi lm nhim v kt ni ra ngoi internet.- Nh vy, thit k m hnh mng ta cn c nhng thit b:

1 router nh tuyn kt ni vi mng internet Dng 3 switch 32 cng cho mi ta nh

ng dy cp quang kt ni gia cc ta nh v cp xon i kt nicc thit b trong mi ta nh

- M hnh:


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2. M t s lc cc thit b cn dng:- Switch: c chc nng tng t nh hub. im khc nhau gia chng l khi 1PC trn mng cn lin lc vi my tnh khc, swith s dng 1 tp hp cc knhlogic ni b thit lp ng dn logic ring bit gia hai my tnh. C nghal hai my tnh hon ton t do lin lc vi nhau m khng cn phi lo lngv xung t.

- Switch v Hub c chc nng kt ni nhiu my tnh vi nhau thng qua portca chng, nhng vi Hub khi cc my tnh ni vo port ca n th s d bnghn mng v cng trong vng tranh chp, cn switch th mi port l 1 vngring bit nn n chuyn frame nhanh hn.- Router: l 1 thit b nh tuyn cho 2 hay nhiu mng c th truyn d liuvi nhau, c th cc mng ny khc a ch IP.- Cp xon i: gm nhiu cp dy ng xon li vi nhau nhm chng pht xnhiu in t. Do gi thnh thp nn cp xon c dng rt rng ri. C hai

loi cp xon i c s dng rng ri trong LAN l: loi c v bc chngnhiu v loi khng c v bc chng nhiu. Cp xon i ch truyn tt tn hiutrong phm vi 100m nn ta dng kt ni cc thit b trong mi ta nh.- Cp quang: c cu to gm dy dn trung tm l si thy tinh hoc plastic c tinh ch nhm cho php truyn i ti cc tn hiu nh sang. Si quangc trng mt lp nhm phn chiu cc tn hiu. Cp quang ch truyn songnh sang (khng truyn tn hiu in) vi bng thong rt cao nn khng gp ccs c v nhiu hay b nghe trm. Cp dng ngun sang laser, diode pht x nh

sang. Cp rt bn v suy gim tn hiu rt thp nn on cp c th di n


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vi km. Bng thng cho php n 2Gbps. Nhng cp quang c khuyt im lgi thnh cao v kh lp t.

Cu 2:Hy trnh by cc phng php truy nhp ng truyn vt l trong mng ccb.

1. CSMA v CSMA/CD:- CSMA (Carrier Sense Multiple Access) l phng php cm sng a truy.- Cc giao thc m trong cc trm lm vic lng nghe ng truyn trc khia ra quyt nh mnh phi lm g tng ng vi trng thi ng truyn

c gi l cc giao thc c cm nhn ng truyn (carrier sense protocol).- Cch thc hot ng ca CSMA: lng nghe knh truyn, nu thy knh truynri th bt u truyn khung, nu thy ng truyn bn th tr hon li vic gikhung. C 3 gii php cho vic tr hon gi khung:

Theo di khng kin tr (Nonpersistent CSMA): Nu ng truyn bn,i trong mt khong thi gian ngu nhin ri tip tc nghe li ngtruyn.

Theo di kin tr (persistent CSMA): Nu ng truyn bn, tip tc

nghe ti khi ng truyn ri ri truyn gi tin vi xc sut bng 1. Theo di kin tr vi xc sut p (P-persistent CSMA): Nu ng truyn

bn, tip tc nghe n khi ng truyn ri ri truyn gi tin vi xc sutbng p.

- ng vn c th xy ra trong CSMA: khi mt trm va pht xong th mttrm khc cng pht sinh yu cu pht khung v bt u nghe ng truyn.Nu tn hiu ca trm th nht cha n trm th hai, trm th hai s cho rngng truyn ang rnh v bt u pht khung. Nh vy ng s xy ra. Huqu ca n l khung b mt v ton b thi gian t lc ng xy ra cho nkhi pht xong khung l lng ph. V th, chng ta cn n mt phng php cs ci tin hn: CSMA vi c ch theo di ng (CSMA/CD CSMA withCollision Detection).- CSMA/CD v c bn cng ging vi CSMA: lng nghe trc khi truyn xemng truyn ang ri hay bn (listen before talk). Tuy nhin, CSMA/CD c 2ci tin quan trng l: pht hin ng v lm li sau ng .

Pht hin ng : trm va truyn va tip tc d xt ng truyn.Ngay sau khi ng c pht hin th trm ngng truyn, pht thm


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mt dy nhi (c tc dng tng cng s va chm tn hiu, gip tt c ccmy trm khc trong mng thy c ng ), v bt u lm li saung .

Lm li sau ng : Sau khi b ng , trm s chy mt thut ton gi

l back-off tnh ton li lng thi gian n phi ch trc khi gi likhung. Lng thi gian ny phi l ngu nhin cc trm sau khi quayli khng b ng nhau na.

- Phng php ny thng dng trong cc kin trc mng bus, trong tt ccc trm ca mng c ni trc tip vo bus.

2. Phng php token bus (th bi mng bus):- Nguyn l hot ng: gia cc trm c nhu cu truyn d liu c thit lp

thnh 1 vng logic. Mi trm trong vng logic s bit c a ch ca trmng trc v sau n.- Cng vic u tin ca phng php ny chnh l thit lp vng logic bao gmcc trm ang c nhu cu truyn d liu c xc nh v tr theo mt chui tht m trm cui cng ca chui s tip ngay sau trm u tin. Nu trm nonm ngoi vng logic n ch c th tip nhn d liu dnh cho chng.- Th bi (token) l mt n v d liu c bit c thit lp v lu chuyn trnvng logic cp pht quyn truy nhp ng truyn cho cc trm.

- Khi mt trm nhn c th bi, n c quyn s dng ng truyn trong mtkhong thi gian nht nh truyn mt hoc nhiu n v d liu. Khi truynht d liu hoc ht thi gian quy nh, trm chuyn th bi ti trm k tiptrong vng.- Cc trm khng tham gia vng logic (khng hoc cha c nhu cu truyn dliu) ch c th nhn d liu ch khng c quyn tip nhn th bi.- Vic thit lp v duy tr trng thi thc t ca mng phi thc hin c ccchc nng:

B sung 1 trm vo vng logic (nu cc trm c nhu cu truyn d liu) tm trm.

Loi b 1 trm khi vng logic (khi trm khng c nhu cu truyn d liuna): Khi 1 trm mun ra khi vng s i n khi nhn c th bi sgi thng bo ni trm ng sau ti trm k trc n yu cu trm nyni trc tip vi trm k sau n.

Qun l li: trng a ch (2 a ch u ngh rng n lt mnh).

3. Phng php token ring (th bi mng ring):


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- Phng php ny cng da trn nguyn l dng th bi cp pht truy nhpng truyn, nhng y th bi lu chuyn theo vng vt l ch khng cnthit phi thit lp vng logic nh i vi phng php token bus.- Nguyn l c bn:

Mt th bi lun chuyn ln lt qua tng nt mng Nt no gi th bi s c gi d liu nu th bi cn trng

Gi d liu xong phi chuyn th bi i. V vy, khi th bi ang bn thnhng trm khc mun truyn d liu phi i.

- Mt s vn : tn thi gian truyn th, tr, mt th bi lm cho trn vogfkhong cn th bi lu chuyn na, Th bi bn lu chuyn khng dng - Khc phc:

Mt th bi: Quy nh trc 1 trm iu khin ch ng. Trm ny phthin tnh trng mt th bi bng cch dng c ch time-out v phc hibng cch pht i mt th bi ri mi.

Th bi bn lu chuyn khng dng: Trm monitor s dng 1 bit trnth bi nh du khi gp mt th bi bn i qua n. Nu n gp lith bi bn vi bit nh du th c ngha trm ngun khng nhn lic n v d liu ca mnh v th bi c quay vng my trmmonitor i bit trng thi ca th bi thnh ri v chuyn tip trnvng.

4. So snh CSMA/CD v token-passing (cc phng php truyn th bi):- CSMA/CD n gin hn so vi token-passing, cng vic phi lm cng t hn.- Hiu qu ca phng php dng th bi khng cao: mt trm c th phi ikh lu mi c th bi. Tuy nhin, token-passing c hiu qu cao hnCSMA/CD trong cc trng hp ti nng.- Cc phng php dng th bi c kh nng iu ha lu thng trong mngbng cch cho php cc trm truyn s lng n v d liu khc nhau khi nhnc th bi, hoc thit lp ch u tin cp pht th bi cho cc trm chotrc.

Cu 3:Trnh by m hnh h thng m OSI 7 tng. Trnh by chi tit chc nng catng tng. ngha ca chun kt ni IEEE 802.* v ISO 8802.*. Cho v d.


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1. M hnh OSI:- M hnh OSI (Open Systems Interconnection Reference Model, m hnh thamchiu kt ni cc h thng m) l mt thit k da vo nguyn l tng cp, lgii mt cch tru tng k thut kt ni truyn thng gia cc my vi tnh v

thit k giao thc mng gia chng.- M hnh OSI bao gm 7 tng, mi tng m t mt phn chc nng c lp.c tnh ca mi tng l n ch s dng chc nng ca tng di n, ng thich cho php tng trn s dng chc nng ca mnh.- Mt h thng ci t cc giao thc bao gm mt chui cc tng ni trn cgi l chng giao thc (protocol stack). Chng giao thc c th c ci ttrn phn cng, phn mm hoc t hp ca c hai. Thng thng ch c nhngtng thp l c ci t trong phn cng, cn nhng tng cao hn c ci t

trn phn mm.- OSI nh ngha cc quy tc ca nhng ni dung sau:

Cch thc cc thit b giao tip v truyn thng c vi nhau Cc phng php cc thit b trn mng khi no th c truyn d

liu, khi no th khng Cc phng php m bo truyn ng d liu v ng bn nhn

Cch thc vn ti, truyn, sp xp v kt ni vi nhau

Cch thc m bo cc thit b mng duy tr tc truyn d liu thchhp

Cch biu din mt bit thit b truyn dn- M hnh OSI gii quyt c vn khng ng nht gia cc thit b mngbi cc my khc nhau vn lin lc c vi nhau min l:

Chng cng ci t mt tp hp cc chc nng truyn thng

C cng s tng v chc nng ca mi tng l nh nhau Cc tng ng mc s dng cng mt giao thc

- V nguyn tc, tng n ca mt h thng ch giao tip, trao i thng tin vitng n ca h thng khc. Mi tng s c cc n v truyn d liu ring:

Tng vt l: bit

Tng lin kt d liu: Khung (Frame) Tng mng: Gi tin (Packet)

Tng vn chuyn: on (Segment)Trong thc t, d liu c gi i t tng trn xung tng di cho n tngthp nht ca my tnh gi. , d liu s c truyn i trn ng truyn

vt l. Mi khi d liu c truyn xung tng pha di th n b "gi" litrong nv d liu ca tng di. Ti bn nhn, d liu s c truyn ngc


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ln cc tng cao dn. Mi ln qua mt tng, n v d liu tng ng s ctho ra. n v d liu ca mi tng s c mt tiu (header) ring.

2. Chi tit chc nng ca tng tng trong m hnh OSI:

- Tng 7: Tng ng dng (Application Layer): l giao din gia cc chngtrnh ng dng ca user v mng. Lp Application x l truy nhp mng chung,

kim sot lung v phc hi li. Lp ny khng cung cp cc dch v cho lpno m cung cp cc dch cho ng dng nh: truyn file, gi/nhn email, telnet,HTTP, FTP, SMTP - Tng 6: Tng trnh by (Presentation Layer): tha thun khun dng traoi d liu. m bo cc my tnh c kiu nh dng d liu khc nhau vn cth trao i thng tin cho nhau. Thng thng cc my tnh s thng nht vinhau v mt kiu nh dng d liu trung gian trao i thng tin gia ccmy tnh. Mt d liu cn gi i s c Presentation Layer chuyn sang nh

dng trung gian trc khi n c truyn ln mng. Ngc li, khi nhn d liut mng, tng trnh by s chuyn d liu sang nh dng ring ca n.- Tng 5: Tng giao dch (Session Layer): thit lp, qun l v kt thc ccphin thng tin gia 2 thit b truyn nhn. Cho php cc ng dng thit lp, sdng v xa cc knh giao tip gia chng (c gi l giao dch). N cung cpc ch cho vic nhn bit tn v cc chc nng bo mt thng tin khi truyn quamng.- Tng 4: Tng vn chuyn (Transport Layer): o bo truyn ti d liu

gia cc qu trnh. D liu gi i c m bo khng c li, theo ng trnh


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t, khng b mt mt, trng lp. i vi cc gi tin c kch thc ln, tng nys phn chia chng thnh cc phn nh hn trc khi gi i, cng nh tp hpli chng khi nhn c.- Tng 3: Tng mng (Network Layer): m bo cc gi tin d liu c th

truyn t my tnh ny sang my tnh khc cho d khng c ng truyn vt ltrc tip gia chng. N nhn nhim v tm c i cho d liu n cc chkhc nhau trong mng.- Tng 2: Tng lin kt d liu (Data link Layer): m bo truyn ti cackhung d liu (frame) gia 2 my tnh c ng truyn vt l ni trc tip vinhau. N ci t c ch pht hin v x l li d liu nhn.- Tng 1: Tng vt l (Physical Layer): iu khin vic truyn ti tht s cc bit trn ng truyn vt l. nh ngha cc tn hiu in, trng thi ng

truyn, phng php m ha d liu, cc loi u ni c s dng.

3. ngha ca chun kt ni IEEE 802.* v ISO 8802.*:- Bn cnh vic chun ha cho mng ni chung dn n kt qu c bn nht lm hnh tham chiu OSI. Vic chun ha mng cc b ni ring c thchin t nhiu nm nay p ng s pht trin ca mng cc b.- IEEE (Institute of Electrical and Electronic Engineers - Hc Vin k nghin v in T) l t chc i tin phong trong lnh vc chun ha mng cc

b vi n IEEE 802 (IEEE 802 Project), kt qu l mt lot cc chun thuch IEEE 802.* ra i. Cui nhng nm 80, t chc ISO tip nhn h chunny v ban hnh thnh chun quc t di dng m hiu tng ng l ISO8802.* .- V d:

IEEE 802.1 l chun c t kin trc mng, kt ni gia cc mng v vicqun tr mng i vi mng cc b.

IEEE 802.2 l chun c t tng dch v giao thc ca mng cc b.

IEEE 802.3 l chun c t mt mng cc b da trn mng Ethernet niting ca Digital, Intel v Xerox hp tc xy dng t nm 1980.

IEEE 802.4 l chun c t mng cc b vi topo mng dng Bus dngth bi iu khin vic truy nhp ng truyn.

IEEE 802.5 l chun c t mng cc b vi topo mng dng vng (ring)dng th bi iu khin vic truy nhp ng truyn.

IEEE 802.6 l chun c t mng tc cao kt ni vi nhiu mng ccb thuc cc khu vc khc nhau ca mt th (MAN).


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IEEE 802.9 l chun c t mng tch hp d liu v ting ni bao gm 1knh d b 10 Mbps cng vi 96 knh 64 Kb/s. Chun ny c thit kcho mi trng c lng lu thng ln v cp bch.

IEEE 802.10 l chun c t v an ton thng tin trong cc mng cc bc kh nng lin tc.

IEEE 802.11 l chun c t mng cc b khng dy (Wireless LAN)hin ang c tip tc pht trin.

IEEE 802.12 l chun c t mng cc b da trn cng ngh c xut bi AT&T, IBM v HP gi l 100 VG - AnyLAN. Mng ny c topomng hnh sao v 1 phng php truy nhp ng truyn c iu khintranh chp. Khi c nhu cu truyn d liu, mt trm s gi yu cu nHub v trm ch c truyn d liu khi Hub cho php.

Cu 4: Hy trnh by v m hnh TCP/IP, chc nng ca mi lp trong TCP/IP. Sosnh vi m hnh OSI 7 tng.

1. M hnh TCP/IP:- TCP/IP (TCP/IP Internet Protocol Suite, b giao thc lin mng) c t tntheo 2 giao thc quan trng nht v c a vo m hnh u tin, l TCP(Transmission Control Protocol) v IP (Internet Protocol). N bao gm mt tphp cc chun c t chi tit cch thc my tnh thng tin lin lc vi nhau,cng nh cc quy c cho cc mng lin kt vi nhau (interconnect) v nhtuyn giao thng.

2. Cc tng ca TCP/IP:bao gm 4 tng.


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- Tng 4: Tng ng dng (Application Layer): l tng hp ca 3 tng ngdng, trnh by v giao dch trong m hnh OSI. N c cc chc nng:

Qun l cc giao thc, h tr vic trnh by, biu din thng tin, m ha,

qun l cuc gi H tr cc giao thc truyn file, email hay remote login nh FTP, TFTP

(Trivial File Transfer Protocol), SMTP, Telnet, SNMP(Simple NetworkManagement Protocol), DNS.

FTP: dch v truyn file nh phn 2 chiu to cu ni

TFTP: truyn file khng to cu ni, hot ng nhanh hn FTP SMTP: qun l hot ng truyn email

Telnet: cung cp kh nng truy nhp my tnh t xa SNMP: gim st v iu khin thit b mng DNS: h thng qun l tn min

- Tng 3: Tng vn chuyn (Transport Layer): tng ng vi tng vnchuyn trong m hnh OSI.

Nhim v c bn: cung cp phng tin lin lc, vn chuyn t 1 chngtrnh ng dng ny ti 1 chng trnh ng dng khc (end-to-end).

Bo m tin cy, d liu n ni m khng c li v theo ng th t.

2 giao thc ca tng ny l TCP v UDP (User Datagram Protocol). TCP: giao thc iu khin vic truyn d liu, yu cu truyn li khi pht

hin li. L giao thc hng kt ni, tin cy, truyn d liu dng byte cth t. C kh nng iu khin lung: bn gi khng truyn vt qu khnng bn nhn, iu khin tc nghn: bn gi gim tc khi mng tcnghn. ng dng: HTTP (web), FTP (file transfer), Telnet (remote login),SMTP (email)

UDP: cng l mt giao thc truyn d liu nhng UDP khng hng kt

ni, khng tin cy, khng iu khin lung v khng iu khin tcnghn. N thng c dng trong cc ng dng: truyn dng media, hingh truyn hnh, DNS, in thoi Internet

- Tng 2: Tng Internet (Internet Layer): tng ng vi tng Networktrong m hnh OSI.

Nhim v c bn: x l vic lin lc ca cc thit b trn mng, mnhim vic chn la ng i tt nht cho cc gi tin. Giao thc chnhhot ng tng ny l giao thc IP.

IP thc hin 2 chc nng c bn:


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nh a ch v nh danh host (host addressing andidentification)

nh tuyn cho gi tin (packet routing) Cc giao thc khc: ICMP, IGMP, ARP, RARP

- Tng 1: Tng giao tip mng (Network Interface Layer): tng ng vichc nng ca 2 lp Data Link v Physical ca m hnh OSI.

nh ra cc th tc giao tip vi cc phn cng mng v truy nhp mitrng truyn

Cc chc nng ca tng giao tip mng bao gm nh x a ch IP sanga ch vt l v gi cc gi IP thnh cc frame. Cn c vo dng phncng v giao tip mng, lp giao tip mng s xc lp kt ni vi ngtruyn vt l ca mng.

Chia thnh 2 tng con: Lp vt l: lm vic vi cc thit b vt l, truyn ti dng bit 0, 1

t ni gi n ni nhn Lp lin kt d liu: ti y d liu c t chc thnh cc khung

(frame). Phn u khung cha a ch v thng tin iu khin,phn cui khung dnh cho vic pht hin li.

3. So snh TCP/IP v OSI:- Ging nhau:

C hai u c kin trc phn lp u c lp ng dng, mc d cc dch v mi lp khc nhau

u c cc lp Transport v Network (hay Internet).

u h tr k thut chuyn mch gi Ging nhau v mi lin h trn di v ngang hng gia cc tng

- Khc nhau:

M hnh TCP/IP gp 2 lp Session v Presentation vo trong lpApplication

M hnh TCP/IP kt hp lp Data Link v lp Physical thnh lpNetwork Interface

TCP/IP c t lp hn nn n gin hn

Cu 6:

Hy trnh by v vai tr ca giao thc trong kin trc phn tng. Ly v d ccgiao thc c trong thc t minh ha cc vn trn.


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1.Vai tr ca giao thc trong kin trc phn tng:- Xem thm: phn v giao thc cu 19- Hai thnh phn b phn 2 my tnh khc nhau, nhng cng cp lun lun

thng nht vi nhau v cch thc m chng trao i thng tin. Qui tc trao ithng tin ny c m t trong mt giao thc.iu y dn n cc giao thc s t chc cc dch v m mt mng my tnhcung cp thnh cc tng/lp (layers). Chc nng ca tng tng tng ng vicc giao thc. Nh vy giao thc v s phn cp th bc ca giao thc (protocolhierarchy) chnh l nn tng cho kin trc phn tng.- Phn tng giao thc gip n gin thit k v d dng thay i, nng cp mhnh.

2. V d:- TCP v UDP l 2 giao thc nm trong tng vn chuyn (Transport Layer) cam hnh TCP/IP. C 2 giao thc ny cng lm nhim v iu khin vic truynd liu, ng vi chc nng ca tng vn chuyn. S khc bit gia chng lTCP l giao thc hng kt ni, ng tin cy cn UDP th ngc li.

Cu 7:Hy trnh by v cu trc ca a ch IP? ngha ca s phn lp a ch?Cch qun l cc a ch IP? Trnh by chi tit v cc a ch IP dng ring.

1. Cu trc ca a ch IP:- Mi thit b trong h thng mng ca chng ta c t nht 2 a ch. Mt a chl Media Access Control (MAC) v mt a ch Internet Protocol (IP). a ch


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MAC l a ch ca card mng gn vo bn trong thit b, n l duy nht vkhng h thay i. a ch IP c th thay i theo ngi s dng ty vo mitrng mng.- a ch IP ang c s dng hin ti (IPv4) c 32 bits chia thnh 4 octet (mi

octet c 8 bits, tng ng 1 byte) v c phn cch nhau bi 3 du chm (.).Gi tr ca mi byte c vit li di dng thp phn,vi gi tr hp l nmtrong khong t 0 255. a ch IP c chia lm 2 phn:

Network ID: phn nhn dng mng, c dng nhn dng 1 mng vphi c gn bi trung tm thng tin mng internet.

Host ID: phn nhn dng my tnh: nhn dng 1 my tnh trong mtmng.

V d: 1 a ch IP: 192.168.1.108. Mi k t trn i din cho 1 con s do

ngi s dng my tnh, modem hoc my ch c chc nng ring gn chochng.

2. ngha ca s phn lp a ch IP:- Ban u, mt a ch IP c chia thnh 2 phn:

Network ID: xc lp bi octet u tin Host ID: xc nh bi 3 octet cn li

- Vi cch chia ny, s lng network b gii hn con s 256, qu t so vi

nhu cu thc t. vt qua gii hn ny, vic phn lp mng c nhngha, to nn mt tp hp lp mng y (classful).- to ra cc mng vi s mng hoc s host khc nhau ty vo mc ch sdng ca tng ni m ngi ta chia a ch IP ra thnh cc lp khc nhau: A, B,C, D v E. Trong ch c lp A, B, C c dng cho cc mc ch thngmi. Lp D c dng cho vic pht cc thng tin broadcast/multicast IP. LpE c dnh ring cho nghin cu.

- Lp A: Phc v cho mt s t cc t chc ln0 Net ID: 7bits

Host ID: 24 bits

Ti a c 27 2 = 126 mng v 224 2 host / mng: 1.0.0.0 n127.255.255.255

- Lp B: Phc v co cc t chc c kch thc trung bnh1 0 Net ID: 14 bits Host ID: 16 bits

Ti a c 214-2 mng v 216-2 host / mng: 128.0.0.0 n 191.255.255.255


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- Lp C: Phc v cho cc t chc c kch thc nh1 1 0 Net ID: 21 bits Host ID: 8

bitsTi a c 224-2 mng v 28-2 host / mng: 192.0.0.0 n 223.255.255.255

- Lp D: multicast1 1 1 0 Multicast: 28 bits

Ti a c 228-2 multicast group: 224.0.0.0 n 239.255.255.255. Tt c cc sln hn 223 trong trng u l thuc lp D. Lp D dng gi IP Datagramn 1 nhm cc host trn 1 mng.

- Lp E: d phng cho tng lai

- Tuy nhin, cc nh qun tr mng thng phn chia mng ca h ra thnhnhiu mng nh hn gi l mng con subnet.

3. Cch qun l cc a ch:- a ch IP cn c qun l mt cch hp l nhm trnh xy ra cc xung tkhi ng thi c 2 a ch IP ging nhau trn cng mt cp mng my tnh.- cp mng ton cu (internet), mt t chc ng ra qun l cp pht cc di

IP cho cc nh cung cp dch v kt ni Internet (IXP, ISP) cc di IP cungcp cho khch hng ca mnh.- cp mng nh hn (WAN), ngi qun tr mng cung cp n cc lp chocc mng nh hn thng qua my ch DHCP.- cc mng nh hn na (LAN) th vic qun l a ch IP ni b thng docc modem ADSL (c DHCP) gn a ch IP cho tng my tnh (khi thit tch t ng trong h iu hnh) hoc do ngi s dng t thit t.

4. Cc a ch IP dng ring:- a ch IP cng cng l danh nh c tnh ton cu v c tiu chun ha.Cc a ch IP cng cng l duy nht v c cung cp t 1 nh cung cp dchv hay ng k vi mt chi ph no .- a ch IP ring: Cc mng ring khng kt ni vo internet c th dng bt k1 a ch host no, min l mi host trong mng ring l duy nht.- Cc khi a ch IP ring:

A: 10.0.0.0 10.255.255.255B: 172.16.0.0 172.31.255.255

C: 192.168.0.0 192.168.255.255- Cc a ch IP dng ring ca cc lp nh sau:


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Lp A: 10.0.0.1 n 10.255.255.254Lp B: 172.16.0.1 n 172.31.255.254Lp C: 192.168.0.1 n 192.168.255.254

Cu 8:Hy trnh by khi nim subnet mask, ngha v cch s dng subnet mask xc nh a ch mng.Trnh by cu trc nh a ch mng con (subnet)? Cch xc nh khng giana ch mng con v khng gian a ch host trong mng con.

1. Subnet mask:

a. Khi nim:- Khi truyn thng tin, mt my cn phi bit a ch IP ca my nhn c trongcng mng vi mnh hay khng, thc hin iu ny ngoi a ch IP, mtthng s khc gi l subnet mask cn c xc nh cho my.- Subnet mask cng gm 4 s thp phn khng du, mi s gm 8 bits; gi trca subnet mask gm 32 bits c chia lm 2 phn:

Bn tri gm nhng bit 1

Bn phi gm nhng bit 0

- Cc bit 0 xc nh nhng a ch IP no cng nm trn cng mt mng con vin. Thng thng, cc client c cung cp a ch IP i km vi subnet maskkhi ni vo mt ISP.

b. ngha:

Kha li mt phn a ch IP phn bit Network ID v Host ID

Xc nh mt a ch IP ch thuc mng ni b hay thuc mng khc

c. Cch s dng:

- Dng php AND xc nh a ch mng ca 1 host theo cng thc sau:Network Address = IP Address AND Net mask

- V d:Cho a ch host l 198.53.147.45, lp C c subnet mask 255.255.255.0Dng php AND : 198.53.147.45 AND 255.255.255.0 198.53.147.0 lnetwork ID.- xc nh xem 2 a ch IP ca my ch v my ngun c cng a ch 1mng hay khng ta lm theo cc bc sau:

Tnh kt qu php AND gia a ch IP ch v mask ca mng Tnh kt qu php AND gia a ch IP ngun v mask ca mng


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Nu 2 kt qu trng nhau th 2 a ch IP cng mt mng khng phithit lp ng truyn

V d: So snh 2 a ch IP 192.168.1.10 v 192.168.1.102 c cng trnmt mng hay khng? Cho subnet mask 255.255.255.0Gii: 192.168.1.10 = 11000000.10101000.00000001.00001010

255.255.255.0 = 11111111.11111111.11111111.00000000192.168.1.0 = 11000000.10101000.00000001.00000000 network ID = 192.168.1.0

192.168.1.102 = 11000000.10101000.00000001.01100110255.255.255.0 = 11111111.11111111.11111111.00000000192.168.1.0 = 11000000.10101000.00000001.00000000 network ID = 192.168.1.0Vy 2 a ch trn l cng 1 mng

2. To mng con (subnetting):- Phn mng con l mt k thut cho php nh qun tr mng chia mt mngthnh nhng mng con nh, nh c cc tin li sau:

n gin ha vic qun tr: Vi s tr gip ca cc router, cc mng cth c chia ra thnh nhiu mng con (subnet) m chng c th c

qun l nh nhng mng c lp v hiu qu hn. C th thay i cu trc bn trong ca mng m khng lm nh hng

n cc mng bn ngoi. Mt t chc c th tip tc s dng cc a chIP c cp m khng cn phi ly them khi a ch mi.

Tng cng tnh bo mt ca h thng: Phn mng con s cho php mtt chc phn tch mng bn trong ca h thnh 1 lin mng nhng ccmng bn ngoi vn thy l 1 mng duy nht.

C lp cc lung giao thng trn mng: Vi s tr gip ca cc router,giao thng trn mng c th c gi mc thp nht c th.

- Internet ch c phn nhn dng mng v cc router trn internet ch quan tmti vic vch ng cho cc gi tin n c router giao tip gia mngintranet bn trong v mng internet bn ngoi. Thng thng ta gi router nyl ca khu ca mng (gateway). Khi 1 gi tin IP t mng bn ngoi n routerca khu, n s c phn nhn dng my tnh xc nh xem gi tin ny thucv mng con no v s chuyn gi tin n mng con , ni m gi tin s cphn pht n my tnh nhn.- Nguyn tc chung thc hin phn mng con:


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Phn nhn dng mng (network ID) ca a ch mng ban u c ginguyn

Phn nhn dng my tnh ca a ch mng ban u c chia thnh 2phn: phn nhn dng mng con (Subnet ID) v phn nhn dng my tnhtrong mng con (Host ID).

phn mng con ngi ta phi xc nh mt n mng con(subnetmask). Mt n mng con l 1 a ch IP m gi tr cc bit phnnhn dng mng (Network Id) v phn nhn dng mng con (Subnet Id)u l 1, trong khi gi tr cc bit phn nhn dng my tnh (Host Id) ul 0.

Khi c c mt n mng con, ta c th xc nh a ch mng con(Subnetwork address) m 1 a ch IP c xc nh bng cng thc sau:

Subnetwork Address = IP & Subnetmask Cch xc nh khng gian a ch mng con v khng gian a ch host

trong mng con gm 3 bc:1)Xc nh Subnet mask2)Lit k ID ca cc Subnet mi3) Cho bit IP address range ca cc HostID trong mi Subnet

- V d: Xt a ch mng lp B 139.12.0.0, vi subnet mask l 255.255.0.0.Chia mng ny ra lm 4 subnet.

Bc 1: Xc nh Subnet mask: Y = 2X

Y: s subnet (=4)X: s bit cn mn X = 2

Lp B c 16 bits lm network ID v 16 bits lm host ID S bit lm host ID: 16 2 = 14 bits S host ti a c trong mi subnet: 214 2 = 16382

Bc 2: Lit k ID ca cc Subnet mi:Trong a ch IP mi (139.12.0.0/18) 18 bits u tin ca 32 bits IP

address dng biu din a ch IP ca mt subnet. Nh vy NetworkID ca 4 subnets mi c l:

Subnet Subnet ID trong dng nh phn Subnet ID

1 10001011.00001100.00000000.00000000 139.12.0.0/18

2 10001011.00001100.01000000.00000000 139.12.64.0/18

3 10001011.00001100.10000000.00000000 139.12.128.0/18

4 10001011.00001100.11000000.00000000 139.12.192.0/18


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Bc 3: Cho bit IP address range ca cc Host ID trong mi Subnet:Ta c 14 bits dng cho Host ID. Da trn lut: dng cho Host ID tt cmi bits khng th u l 0 hoc 1 do ta c bng IP Address cacc Host ID trong mi subnet:

Subnet HostID IP address trong dng nh phn HostID IPaddressRange

1 10001011.00001100.00000000.0000000110001011.00001100.00111111.11111110

139.12.0.1/18 139.12.63.254/18

2 10001011.00001100.01000000.0000000110001011.00001100.01111111.11111110

139.12.64.1/18 139.12.127.254/18

3 10001011.00001100.10000000.0000000110001011.00001100.10111111.11111110

139.12.128.1/18 139.12.191.254/18

4 10001011.00001100.11000000.0000000110001011.00001100.11111111.11111110

139.12.192.1/18 139.12.255.254

Cu 9:Hy trnh by v cu trc gi d liu IP.Hy trnh by v s phn mnh v hp nht datagram.

1. Cu trc gi d liu IP:- IP l giao thc cung cp dch v truyn theo kiu khng kt ni(connectionless). Phng thc khng lin kt cho php cp trm truyn nhnkhng cn phi thit lp kt ni trc khi truyn d liu v do khng cnphi gii phng lin kt khi khng cn nhu cu truyn d liu na. Phng thckt ni khng kt ni cho php thit k v thc hin giao thc trao i d liun gin (khng c c ch pht hin v khc phc li truyn). Cng chnh v th tin cy trao i d liu ca giao thc ny khng cao.- Cc gi d liu IP c nh ngha l cc datagram. Mi datagram c phntiu (header) cha cc thng tin cn thit chuyn d liu (v d: IP catrm ch). Nu a ch IP ch l a ch ca 1 trm nm trn cng 1 mng IPvi trm ngun th cc gi d liu s c chuyn thng n a ch ch, nukhng cc gi d liu s c gi n mt my trung chuyn IP gateway chuyn tip. IP gateway l mt thit b mng IP m nhn vic lu chuyn ccgi d liu IP gia 2 mng IP khc nhau.- Cu trc gi d liu IP c m t trong hnh sau:


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Version (phin bn): xc nh phin bn ca giao thc ang c sdng

IP Header Length (chiu di ca phn tiu ): xc nh chiu di caphn tiu ca gi tin, tnh bng n v l t -32 bits (32 bits word).

Type of Service (kiu ca dch v): c t mc quan trng m giaothc pha trn mun x l gi tin.

Total Length (tng chiu di gi tin): c t chiu di, tnh bng byte,ca c gi tin IP (bao gm c phn d liu v phn tiu ).

Identification (s nhn dng): S nguyn nhn dng gi tin DL hinhnh. Trng ny c s dng rp li cc phn on ca gi tin.

Flags (c hiu): Gm 3 bits, bit c trng s nh xc nh gi tin c bphn on hay khng. Bit th 2 xc nh y c phi l phn on cuicng ca gi tin hay khng. Bit c trng s ln nht cha s dng.

Fragment offset (v tr ca phn on): Biu th v tr ca phn on dliu so vi v tr bt u ca gi d liu gc, n cho php my nhn xydng li gi tin ban u.

Time to live (thi gian sng ca gi tin): Lu tr b m thi gian, gi trs c gim dn cho ti khi n c gi tr 0 th gi tin b xa. iu nygip ngn nga tnh trng gi tin c truyn i lng vng khng bao giti ch.

Protocol (giao thc): Biu hin giao thc tng trn s nhn gi tin khin c giao thc IP x l.


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Header checksum (tng kim tra li tiu ): kim tra tnh ton vn caphn tiu .

Source address: a ch IP my gi gi tin

Destination address: a ch IP my nhn gi tin

Options: ty chn cho php h tr mt s vn , nh vn bo mt. Data: cha d liu tng trn gi xung cn truyn i

2. S phn mnh v hp nht datagram:- Mi mng s quy nh kch c ti a ca cc datagram chy trong n. S giihn ny xut pht t nhiu l do:

Phn cng:v d nh kch c gii hn ca khung Ethernet

H iu hnh: v d tt c cc buffer u c kch thc 512 bytes Giao thc: s lng cc bit trong trng ch chiu di ca gi tin

Tng thch vi mt chun quc gia / quc t no

Mong mun gim thiu tc ng ca vic truyn li do li gy ra Mong mun ngn chn mt gi tin chim ng truyn qu lu

cc nhn vin thit k mng khng c t do chn kch thc gi tin ti anh thch ca h. Kch thc ti a ca d liu thay i t 45 bytes (ATMcell) n 65515 (gi tin IP).

khi mt gi tin ln mun i ngang mt mng con c kch thc gi tin ti aqu nh, cn cho php cc chia nh gi tin thnh nhiu mnh (fragment), gicc mnh ny i nh mt gi tin c lp.

a. Phn mnh datagram:- MTU (Maximum Transfer Unit) l di ti a ca mt gi d liu kt ni.- Chiu di ti a ca IP datagram l 65535 bytes.Khi i qua cc mng c MTU nh hn th cn phn mnh, khi ti ch mithc hin hp nht (reassembly).

- IP dng c MF (3 bit thp ca trng Flags trong gi IP) v trng Flagmentoffset ca gi IP gc. Cc gi trong cng chui phn mnh u c trng nyging nhau, MF = 1 nu l gi u ca chui phn mnh v = 0 nu l gi chuica gi c phn mnh.

b. Hp nht datagram:- C 2 chin lc ti hp cc mnh li thnh gi tin gc: trong sut v khngtrong sut.- Phn mnh trong sut: Khi 1 gi tin ln i qua mt mng con v mng con

ny quyt nh phi phn mnh gi tin, mt gateway ca mng con s lm


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nhim v phn mnh gi tin ln . Khi cc mnh i ht qua mng con, phi cmt gateway khc ng ra tp hp li chng, ti to gi tin ban u v chuyntip n mng con k tip. mng con k tip gi tin li c phn mnh v tihp li nh trn.

Khuyt im: Gateway u ra phi bit khi no n thu lm li ht cc phn

mnh

Lm sao mi phn mnh phi i ra cng mt gateway

Chi ph b ra phn mnh v ti hp gi tin l ln khi n i quahng lot cc mng con

- Phn mnh khng trong sut: Cc mng con trung gian c th phn mnhgi tin ln, nhng khng c nhim v ti hp li n. Vic ti hp ch c thchin ti ch n ca gi tin ny. Chin lc ny i hi mi host trong mng ckh nng ti hp thng tin. Ngoi ra cn lm pht sinh chi ph cho cc headerca cc mnh con.u im: do chin lc ny c quyn chn la nhiu gateway u ra mngcon, cho nn hiu sut vch ng v truyn gi tin tng ln nhiu ln.

Cu 10:Trnh by v chin lc nh tuyn. Vic nh tuyn c din ra ti lp noca chng giao thc TCP/IP?Trnh by v hot ng ca giao thc ICMP khi cn nh tuyn li.

1. Chin lc nh tuyn:- nh tuyn (routing) l qu trnh chn la cc ng i trn mt mng mytnh gi d liu t trm ngun ti trm ch.- Cc gi d liu c truyn t h thng ny sang h thng khc phi cnh tuyn qua mt dy cc nt. Mi nt nhn gi d liu t mt ng vo richuyn tip n ti mt ng ra hng n ch ca d liu.- Hot ng:

Khi mun trao i thng tin vi mt trm khc, IP s xc nh trm ny ltrm nm trong mng cc b hay bn ngoi.

Nu trm ch ngoi mng, IP s kim tra bng nh tuyn tm mttuyn ti mt trm mt mng ngoi.

Nu khng tm thy mt tuyn no IP s s dng mt a ch cnggateway mc nh truyn gi tin n mt b nh tuyn.


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- b nh tuyn, bng nh tuyn c truy vn tm ng n mng bnngoi. Nu khng tm thy ng, gi tin s c gi n mt a ch cngmc nh ca b nh tuyn.- Khi tm thy mt tuyn, gi tin s c b nh tuyn k tip, c gi l mt

b hop v cui cng s c phn pht n trm ch. Nu khng tm thymt tuyn no c th mt bn tin bo li s c gi ti trm gi gi tin.- Mt quyt nh routing phi thc hin 2 chc nng sau:

- Quyt nh chn ng theo chun ti u no.- cp nht thng tin chn ng, tc l thng tin dng cho chc nng trn.

- a ch IP c chia lm 2 phn: a ch mng (IP Address) v a ch my(MAC). iu ny cho php chia cc mng cc mng IP thnh cc mng conc c trng bi phn a ch mng trong a ch IP. Do vy cc my trm

trong cng mt mng s nm cng trn mt mng con.Mi mng con chu trch nhim chn ng cho cc gi tin IP trong mng camnh, cc gi tin ny c nhn ra nh phn a ch mng ca n. Cc routercc b s c cng a ch mng trong a ch IP ca n ging a ch mng ccb.- Cc b nh tuyn lu tr thng tin bng v kim tra bng nhm xc nhng i ti u trn mng cho cc gi. Nu mng b tc nghn hay kt ni thtbi, cc tuyn thay th khc c th tm thy trn bng.

- Lp bng nh tuyn, mt u vo tnh thm vo bng nh tuyn bao gm: a ch ID mng hoc tn mng ca mng ch, nu tn mng c s

dng th n s c tm trong file networks. Mt n mng: mt mt n mng cho a ch mng.

a ch cng: a ch IP hoc tn trm ca giao din n mng ch, nutn trm c s dng cho cng, th n s c tm trong file Hosts.

- Phn loi nh tuyn: nh tuyn trc tip: l vic xc nh ng ni gia 2 trm lm vic

trong cng mt trm lm vic trong cng mt mng vt l. nh tuyn khng trc tip: l vic xc nh ng ni gia 2 trm lm

vic khng nm trong cng mt mng vt l v v vy vic truyn tin giachng phi c thc hin thng qua trm trung gian (gateway).

- Trong thut ng truyn thng ca TCP/ IP ch c 2 kiu thit b l cc cngtruyn v cc trm. Cc cng truyn c vai tr gi cc gi d liu, cn trm thkhng. Tuy nhin khi mt trm c ni vi nhiu mng th n cng c th nhhng cho vic lu chuyn cc gi d liu gia cc mng v lc ny ng vaitr hon ton ging nh mt gateway.


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- Cc trm lm vic lu chuyn cc gi d liu xuyn sut qua 4 lp trong khicc cng tuyn ch chuyn cc gi n lp Internet l ni quyt n tuyn ngtip theo truyn cc gi d liu.- Cc my ch c th truyn d liu n cc my khc nm trn cng mng vt

l.

2. Hot ng ca giao thc ICMP khi cn nh tuyn li:- nh hng cc tuyn ng: mt thit b nh tuyn s gi mt thngipICMP nh tuyn li thng bo vi mt trm l nn dng thit b nhtuyn khc ti thit b ch. Thng ip ny c th ch c dng khi trmngun trn cng mt mng vi c 2 thit b nh tuyn.- Tc dng ca ICMP Redirect l cho mi host vi nhn bit ti thiu v nh

tuyn xy dng ln mt bng nh tuyn tt hn theo thi gian. Host c th btu vi mt tuyn mc nh, bt c ln no tuyn mc nh ny c dng vihost th n s c router mc nh gi thng bo Redirect cho php host cp nht bng nh tuyn ca n mt cch ph hp hn.

Cu 11:Trnh by v hot ng ca giao thc ARP.

- Mi thit b trong h thng mng ca chng ta c t nht 2 a ch. Mt a chl Media Access Control (MAC) v mt a ch Internet Protocol (IP). a chMAC l a ch ca card mng gn vo bn trong thit b, n l duy nht vkhng h thay i. a ch IP c th thay i theo ngi s dng ty vo mitrng mng.- Vi mng TCP/IP, gi tin phi cha c a ch MAC ch v a ch IP ch.Nu mt trong hai a ch ny khng ng th gi tin cng xem nh khng gi

c ti ch. ARP l mt giao thc dng tm a ch MAC ca mt thit bmng da trn a ch IP bit.- Mt vi thit b c lu tr bng cha a ch IP v a ch MAC tng ng IP, bng ny c gi l bng ARP. Khi thit b gi gi tin ln mng n s sdng thng tin trong bng ARP ny.- C 2 cch thu thp thng tin cho a ch MAC:

Cch 1: Khi c mt gi tin c gi trn ng truyn, thit b lun kimtra a ch ch ca gi tin c phi ca mnh hay khng? Sau khi kim tra,

a ch IP v a ch MAC u c lu vo trong bng ARP.


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Cch 2: thu thp qua gi tin broadcast ARP request. Khi my tnh gimt gi tin broadcast dng ARP request th tt c cc my khc trnmng u phn tch gi tin ny.Nu a ch IP ch ca thit b mng cn tm l a ch thuc cng

n mng vi a ch my gi, my ch s tr li bng mt gitin ARP response (trong c a ch MAC v a ch IP ca my).Trong trng hp a ch ch khng tn ti hoc thit b cha hotng th s khng c gi tin ARP response.

Nu a ch IP ch ca thit b mng cn tm l a ch khc ngmng th vic tm a ch MAC c thng qua Router, li c 2cch thc hin: Nu Router bt tnh nng cho php thc hin Proxy ARP,

khi nhn c gi tin broadcast ARP request, Router skim tra a ch ch c khc ng mng ca a ch ngunkhng? Nu c Router s tr v mt ARP response tr li.

Nu my tnh c khai bo Default Gateway th my tnh sgi gi tin n Default Gateway Default Gateway gitip.

Nu my tnh khng khai bo Default Gateway v tnh nng thchin proxy ARP khng bt th 2 my tnh c a ch ng mng

khc nhau khng th lin lc c vi nhau.

Cu 12:Trnh by v chc nng ca giao thc TCP trong m hnh TCP/IP.Trnh by v cu trc gi tin TCP.

1. Chc nng ca giao thc TCP:- TCP (Transmission Control Protocol) l giao thc cung cp dch v vn

chuyn tin cy, hng kt ni theo kiu truyn thng tin bng cch phn lungcc bytes.- L giao thc truyn 2 hng ng thi, ngha l mi mt kt ni h tr 2lung bytes chy theo 2 hng. N cng bao gm mt c ch iu khin thnglng cho mi lung bytes ny, cho php bn nhn gii hn lng d lium bn gi c th truyn ti mt thi im no .- TCP h tr c ch a hp, cho php nhiu tin trnh trn mt my tnh c thng thi thc hin i thoi vi i tc ca chng.


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- TCP l giao thc hng byte, ngha l bn gi ghi cc bytes ln kt ni TCP,bn nhn c cc bytes t kt ni TCP .- Trong m hnh TCP/IP, giao thc TCP nm tng Transport.

2. Cu trc gi tin TCP:

Mt gi tin TCP gm c hai phn: Header v Data

- Header: c 11 phn, trong c 10 phn bt buc, cn trng th 11 l t

chn c tn l options Souree Port, Destination Port: S hiu ca cng ti my tnh gi, nhn.

Hai trng ny cng vi hai a ch IP ngun v ch s c kt hp vinhau nh danh duy nht mt kt ni TCP.

Sequence Number: Trng ny c hai nhim v:Nu c SYN bt th n l s th t gi ban u v byte u tin

c gi c s th t ny cng them 1.Nu khng c c SYN th y l s th t ca byte u tin.

Acknowledgement Number: Nu c ACK bt th gi tr ca trngchnh l s th t gi tin tip theo m bn nhn cn.

Data Offset: Trng c di 4 bit quy nh di ca phn header.Phn header c di ti thiu l 5 t (160 bit) v ti a l 15 t (480bit).

Reserved: Dnh cho tng lai v c gi tr l 0.

Flags: Bao gm 6 c: URG: C cho trng Urgent pointer. ACK: C cho trng Acknowledgement.


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PSH: Hm Push RST: Thit lp li ng truyn SYN: ng b li s th t FIN: Khng gi thm s liu

Window: S byte c th nhn bt u t gi tr ca trng bo nhn(ACK)

Checksum: 16 bt kim tra cho c phn header v d liu.

Urgent pointer: Nu c URG bt th gi tr trng ny chnh l s t 16bits m s th t gi tin (sequence number) cn dch tri.

Options: y l trng ty chn. Nu c th di l bi s ca 32 bits.

- D liu: Trng cui cng khng thuc v header. Gi tr ca trng ny lthng tin dnh cho cc tng trn (trong m hnh 7 lp OSI). Thng tin v giaothc ca tng trn khng c ch r trong phn header m ph thuc vo cngc chn.

Cu 13:Hy trnh by v hot ng thit lp kt ni v hy kt ni gia mt cp thcth trong m hnh hot ng TCP/IP?

1. Thit lp kt ni:

TCP s dng phng thc bt tay 3 chiu (three-way handshake).


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- Bc 1: Client (bn ch ng) gi n server (thc th cung cp dch v) mtsegment yu cu ni kt, trong cha s th t khi u x m n s dng(Flags = SYN, SequenceNum = x).- Bc 2: Server tr li client bng mt segment, trong bo nhn rng n sn

sng nhn cc bytes d liu bt u t s th t x+1 (Flags = ACK, Ack = x+1)v cng bo rng s th t khi u bn server l y (Flags = SYN,SequenceNum = y).- Bc 3: Cui cng client bo cho server bit n bit s th t khi u caserver l y (Flags = ACK, Ack = y + 1).

2. Hy kt ni:

Vic hy bt tay trong TCP c thc hin qua 4 bc:- Bc 1: Cient (bn ch ng) gi n server mt segment yu cu hy ni kt(Flags = FIN).- Bc 2: Server nhn c mt segment FIN, s tr li bng mt segment

ACK. Sau khi hon tt ht mi th ng ni kt, server s gi cho clienttip mt segment FIN.- Bc 3: Client nhn c FIN s tr li ACK sau n s chuyn sang trngthi ch i c nh hn. Trong thi gian ch i ny, client s tr li ACK chomi khung FIN. Ht thi gian ch i, client s tht s ng ni kt.- Bc 4: Server khi nhn c ACK s tht s ng ni kt.

Cu 14:


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Hy trnh by v cc h thng dung li RAID trong vic m bo an ton dliu trn h thng my tnh.

RAID (Redundant Array of Independent Disks, cm a d phng c lp) l

mt cng ngh h thng dung li m bo an ton d liu mc cao trn hthng my tnh, thng qua k thut sp t cc thit b vo trong cc dy dphng.C nhiu phng n thc hin RAID khc nhau nhm li kh nng chng chuli, t phc hi v tng tc c ghi d liu.

1.RAID 0 (Disk Stripping Ct lt d liu):Khi cn ghi d liu c ch ny chia d liu ra thnh tng khi v ri u chng

ln cc a trong cm. iu ny lm tc c d liu tng ln nhiu v chophp to ra nhng b a (volumes) c kch thc ln t nhiu a vt l. Tuynhin nu s c xy ra d ch vi mt trong cc a th ton b nhm d liulin quan s b mt. V vy, c ch RAID 0 khng c kh nng dung li vngi ta thng phi p dng n phi hp vi cc phng php RAID khc.

2. RAID 1 (Disk Mirroring soi gng a):Mt d liu c ghi hnh 2 bn sao ging nhau t trn 2 a vt l khc nhau.

Khi xa d liu s thc hin trn c 2 a. Khi s c xy ra vi cm a chnh,cm d phng s c s dng ly thng tin ra v cp nht li nhng li ticm a kia.

3. RAID 2:- t ph bin hn, n ch yu c p dng cho my tnh ln v siu my tnh.- Cho php hiu chnh d liu ngay trong khi ang hot ng, thch nghi vi ihi cao v kim tra li v hiu chnh. Khi mt khi d liu c ghi, n b tch

ra v ri u theo kiu Stripping trn tt c cc a vt l trong cm.

4. RAID 3:Truyn song song v c m sa li ECC (Error Correcting Code). C ch kimtra chn l c p dng trong RAID 3 vi tng nhm bit. Lng khng giana hu ch chim khong 85% tng dung lng a.

5. RAID 4 (Data guarding canh gc d liu):


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- Thng tin ban u c km thm cc m kim tra li (CRC), sau c lncc a theo c ch stripping ging RAID 0 theo tng Strip block vi kch thcrt ln. Mt a vt l ring c nhim v cha cc thng tin CRC.- u im: Kh nng chng chu li ca RAID 4 rt cao. Khi mt a trong cm

a vt l b hng, d liu vn c th c khi phc t nhng a cn li v hthng khng phi dng hot ng, do vy c ch ny cn c gi l N+1 data

guarding.- Khuyt im: Khi Disk control b s c th ton b h thng phi dng v acha CRC phi hot ng vi cng cao d tr thnh mt nt c chai(bottle-neck) lm gim hiu sut chung ca mng.

6. RAID 5:

- Tng t nh RAID 4, ch ci tin mt im l thng tin CRC khng nm tptrung trong mt a vt l m c ri u ln cc a trong cm ging nh dliu thng thng. Lm nh vy khin vai tr ca cc a trong cm tr nnbnh ng nh nhau, khng cn a no gnh phn vic nng hn cc a khcdo loi b c nguy c tr thnh nt c chai ca h thng.

Ngoi ra cn nhiu loi RAID khc nhng chng khng c s dng rng rim ch gii hn trong cc h thng my tnh phc v mc ch ring, c th k

nh: Level 4 (Dedicated Parity Drive), Level 6 (Independent Data Disks withDouble Parity), Level 10 (Stripe of Mirrors), Level 7 (thng hiu ca tp onStorage Computer, cho php thm b m cho RAID 3 v 4), RAID S (phtminh ca tp on EMC v c s dng trong cc h thng lu tr Symmetrixca h)

Bi tp v d:

Cho mt a ch IP l dy s: 10010011 10001110 00011010 00000111. Hycho bit:- y l a ch IP lp no? Cho bit subnet mask ca a ch ny?- i sang a ch IP dng thp phn.- c bit rng y l IP c phn mng con v dng 3 bit trong phn Host ID lm a ch mng con. Cho bit subnet mask tch a ch mng con?- Nu a ch ca cc mng con? Mi mng con qun l c ti a bao nhiumy tnh?


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1. y l a ch IP lp BSubnet mask: 255.255.0.0

2. IP Address dng thp phn: 147.142.26.7/16

3. Mn 3 bits trong phn Host ID lm a ch mng con Subnet maskchia mng con: 255.255.224.0Tng s mng con: 23 = 8 (subnets) trong s mng con kh dng: 8 2 = 6(subnets)

4. Host ID cho mn 3 bits nn n ch cn 13 bits tng s host kh dng chomi subnet: 213 2 = 8190 (hosts)

a ch ca cc mng con- subnet 1: 147.142.0.0/19 -> s host t: 147.142.0.1 n 147.142.31.254- subnet 2: 147.142.32.0/19 -> s host t: 147.142.32.1 n 147.142.63.254- subnet 3: 147.142.64.0/19 -> s host t: 147.142.64.1 n 147.142.95.254- subnet 4: 147.142.96.0/19 -> s host t: 147.142.96.1 n 147.142.127.254- subnet 5: 147.142.128.0/19 -> s host t: 147.142.128.1 n 147.142.159.254- subnet 6: 147.142.160.0/19 -> s host t: 147.142.160.1 n 147.142.191.254- subnet 7: 147.142.192.0/19 -> s host t: 147.142.192.1 n 147.142.223.254

- subnet 8: 147.142.224.0/19 -> s host t: 147.142.224.1 n 147.142.255.254Vy 147.142.26.7 thuc 147.142.0.0/19

Cu 19:Trnh by khi nim v Protocol v Topology mng, m hnh client/server vm hnh peer-to-peer, s khc nhau gia chuyn mch knh v chuyn mch

gi.

1. Protocol (Giao thc):

a. Khi nim:- Giao thc (protocol) l tp hp cc lut v th tc thc hin vic truyn thnggia 2 bn truyn thng. Cc giao thc thng bao gm nhng chc nngtruyn tn hiu (signaling), chng thc (authentication), d v v li (detectingand correcting errors).- Cc giao thc ph bin: TCP, IP, HTTP, SMTP, POP - Xem thm: Cu 21


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b. Tm quan trng ca giao thc:- Trong s giao tip ca x hi loi ngi, cc giao thc l nhng quy lut ringbit v cch ni chuyn, cch lng nghe, cch thu hiu V d: Khi 2 ngi Anh quen bit gp nhau, h s cho nhau (Hi! hoc Hello!

hoc ), khi h chia tay nhau h s cho tm bit (Goodbye! See you again!).- i vi cc thit b mng, giao thc cng c tm quan trng ging nh vy.Tuy nhin, my tnh khng th hiu cc giao thc thng thng ca con ngi,v vy cn nhng lut c vit dnh ring cho chng.V d:

Client gi ti server yu cu kt ni (TCP connection request)

Server gi tn hiu hi p (TCP connection response) Client li yu cu get trang web http://hnue.edu.vn Server gi trang web ti my client.

2. Topology (Kin trc mng):

a. Khi nim:- Cc kin trc mng (Network Topology) l s dng biu din cc kiusp xp, b tr vt l ca my tnh, dy cp v nhng thnh phn khc trn mng

theo phng din vt l.- C 2 kin trc mng chnh:

Kin trc vt l (m t cch b tr ng truyn thc s ca mng) Kin trc logic (m t con ng m d liu tht s di chuyn qua cc

nt mng)

b. Cc kiu kin trc mng chnh:- Mng Bus (tuyn):

Kin trc Bus l mt kin trc cho php ni mng cc my tnh n gin

v ph bin nht. N dng mt on cp ni tt c my tnh v cc thitb trong mng thnh mt hng. Khi mt my tnh trn mng gi d liudi dng tn hiu in th tn hiu ny s c lan truyn trn on cpn cc my tnh cn li, tuy nhin d liu ny ch c my tnh c ach so khp vi a ch m ha trong d liu chp nhn. Mi ln ch cmt my c th gi d liu ln mng v vy s lng my tnh trn buscng tng th hiu sut thi hnh mng cng chm.

Hin tng di tn hiu: l hin tng khi d liu c gi ln mng, d

liu s i t u cp ny n u cp kia. Nu tn hiu tip tc khng


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ngng n s di ti lui trong dy cp v ngn khng cho my tnh khcgi d liu. gii quyt tnh trng ny ngi ta dng mt thit bterminator (in tr cui) t mi u cp hp thu cc tn hiu int do.

u im: Kin trc ny dng t cp, d lp t, gi thnh r. Khi m rngmng tng i n gin, nu khong cch xa th c th dng repeater khuch i tn hiu.

Khuyt im: khi on cp t i hoc cc u ni b h ra th s c haiu cp khng ni vi terminator nn tn hiu s di ngc lm cho tonb h thng mng s ngng hot ng. Nhng li nh vy rt kh phthin l hng ch no nn cng tc qun tr rt kh khi mng ln (nhiumy v kch thc ln).

- Mng star (sao): Trong kin trc ny, cc my tnh c ni vo mt thit b u ni trung

tm (Hub hoc switch). Tn hiu c truyn t my tnh gi d liu quahub tn hiu c khuch i v truyn n tt c cc my tnh khc trnmng.

u im: cung cp ti nguyn v ch qun l tp trung. Khi mt oncp b hng th ch nh hng n my dng on cp , mng vn hotng bnh thng. Kin trc ny cho php chng ta c th m rng hocthu hp mng mt cch d dng.

Khuyt im: do mi my tnh u phi ni vo mt trung tm im nnkin trc ny i hi nhiu cp v phi tnh ton v tr t thit b trungtm. Khi thit b trung tm im b hng th ton b h thng mng cngngng hot ng.

- Mng Ring (vng):

Trong mng Ring, cc my tnh v cc thit b ni vi nhau thnh mtvng khp kn, khng c u no h. Tn hiu c truyn i theo mtchiu v qua nhiu my tnh. Kin trc ny dng phng php chuyn thbi (token passing) truyn d liu quanh mng.

Phng php chuyn th bi l phng php dng th bi chuyn t mytnh ny sang my tnh khc cho n khi ti my tnh mun gi d liu.My ny s gi th bi v bt u gi d liu i quanh mng. D liuchuyn qua tng my tnh cho n khi tm c my tnh c a ch khpvi a ch trn d liu. My tnh u nhn s gi mt thng ip chomy tnh u gi cho bit d liu c nhn. Sau khi xc nhn my


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tnh u gi s to th bi mi v th ln mng. Vn tc ca th bi xpx vn tc nh sng.

- Ngoi ra cn c cc kiu kin trc mng khc nh mng Mesh (li), mngCellular (t bo), cc kiu kin trc mng kt hp nh star bus, star ring

3. M hnh Client/Server (khch/ch):- Trong m hnh mng client/server c mt h thng my tnh cung cp cc tinguyn v dch v cho c h thng mng s dng c gi l cc my ch(server), mt h thng my tnh s dng cc ti nguyn c gi l my khch(client).- Server khi nhn c yu cu ca my client s phn tch yu cu hiuc client mun g. Server s gi kt qu theo yu cu v cho client trong cc

thng ip tr li (reply/response).V d: khi web server nhn c yu cu gi t mt trnh duyt web, n s phntch yu cu xc nh client cn nhn trang web no, sau m tp tin htmltng ng trn a cng cc b ca n gi v trnh duyt web trong thngip tr li.- Cc server thng c cu hnh mnh (tc x l nhanh, kch thc lu trln) hoc l cc my chuyn dng. Da vao chc nng c th chia thnh ccloi server nh sau:

File Server: phc v cc yu cu h thng tp tin trong mng Print Server: phc v cc yu cu in n trong mng

Application Server: cho php cc ng dng chy trn cc server v tr vkt qu cho client

Mail Server: cung cp cc dch v v gi v nhn email Web Server: cung cp cc dch v v web

Database Server: cung cp cc dch v v lu tr, tm kim thng tin

Communication Server: qun l cc kt ni t xa- Mt s ng dng: www, mail, ftp - H iu hnh mng thng dng trong m hnh client-server l: Linux,Windows Server, Novell Netware


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- u im: do cc d liu c lu tr tp trung nn d bo mt, backup vng b vi nhau. Ti nguyn v dch v c tp trung nn d chia s v qunl, c th phc v cho nhiu user.- Khuyt im: cc server chuyn dng rt t tin, phi c administrators choh thng.

4. M hnh Peer-to-Peer (mng ngang hng):- Mng ngang hng cung cp vic kt ni c bn gia cc my tnh nhngkhng c bt k mt my tnh no ng vai tr phc v. Mt my tnh trnmng va c th l client, va c th l server. Trong mi trng ny, user trntng my tnh chu trch nhim iu hnh v chia s cc ti nguyn ca mytnh mnh. M hnh ny ch ph vi vi cc t chc nh, s ngi gii hn, vkhng quan tm n vn bo mt.- u im: n gin nn d ci t, t chc v qun tr, chi ph thit b cho mhnh ny thp.

- Khuyt im: khng cho php qun l tp trung nn d liu phn tn, kh

nng bo mt thp, rt d b xm nhp, cc ti nguyn khng c sp xp nnrt kh nh v v tm kim.


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5.Chuyn mch knh v chuyn mch gi:

a. Chuyn mch knh (Circuit Switching):- Ch ny hot ng theo m hnh ca h thng in thoi. c th giaotip vi my B, my A phi thc hin mt cuc gi. Nu my B chp nhn cucgi, mt knh o c thit lp dnh ring cho thng tin trao i gia A v B.- Tt c cc ti nguyn c cp cho cuc gi ny nh bng thng ngtruyn, kh nng ca cc b hon chuyn thng tin u c dnh ring chocuc gi, khng chia s cho cc cuc gi khc, mc d c nhng khong lnthi gian hai bn giao tip im lng.- Ti nguyn (bng thng) s c chia thnh nhiu nhng phn bng nhau vs gn cho cc cuc gi. Khi cuc gi s hu mt phn ti nguyn no , mcd khng s dng n n cng khng chia s ti nguyn ny cho cc cuc gikhc.- Vic phn chia bng thng ca knh truyn thnh nhng phn c th cthc hin bi mt trong hai k thut: Phn chia theo tn s (FDM FrequencyDivision Multi Access) hoc phn chia theo thi gian (TDM Time DivisionMulti Access).

b. Chuyn mch gi (Packet Switching):

- Trong phng php ny, thng tin trao i gia hai my tnh c phn thnhnhng gi tin c kch thc ti a xc nh.- Gi tin ca nhng ngi dng khc nhau s chia s nhau bng thng trn knhtruyn. Mi gi tin s s dng ton b bng thng ca knh truyn khi n cphp. iu ny s dn n tnh trng lng thng tin cn truyn i vt qu khnng p ng ca knh truyn. Trong trng hp ny, cc router s ng x theogii thut lu v chuyn tip (store and forward): lu li cc gi tin cha gi ic vo hng i ch cho n khi knh truyn ri s ln lt gi chng i.

c. S khc nhau gia chuyn mch knh v chuyn mch gi:- Chuyn mch gi cho php nhiu ngi s dng mng hn chuyn mchknh.- Chuyn mch gi cho php chia s bng thng v ti nguyn gia cc users,cn chuyn mch knh th khng.- Chuyn mch knh c tin cy cao hn v tr thp hn so vi chuynmch gi.- Chuyn mch knh thng c p dng vo nhng ni cn vn tc truyn d

liu cao hoc cn truy cp d liu thi gian thc (real-time data access) nhmng in thoi.


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Cu 20:Tnh thi gian gi mt gi tin c kch thc l 1Mb qua 2 phng thc

chuyn mnh knh theo thi gian (TDM) v chuyn mnh knh theo tns(FDM) vi:

ng truyn l 1.5Mbps

ng truyn s dng 24 slot Thi gian thit lp gia 2 host l 500 msec

- ng truyn 1.5 Mbps s dng 24 slot, vy mi slot s dng:1.5 / 24 = 0.0625 (Mbps)

- S dng phng thc TDM:t = ( 1 / 24 ) / 0.0625 + 24 * 0. 5 = 12.67 (s)- S dng phng thc FDM:t= 1/ 0.0625 + 0. 5 = 16.5(s)

Cu 21:Trnh by mt s giao thc trn tng ng dng (HTTP, FTP, DNS, SMTP,

POP3). Hy phn tch cu trc ca gi tin HTTP.

1.HTTP:Giao thc truyn siu vn bn (HTTP Hypertext Transfer Protocol) l mtgiao thc chun trc thuc lp ng dng (Application Layer) dng trao ithng tin gia my cung cp dch v (Web Server) v my dng dch v(Client).- HTTP l mt in hnh request-response ca m hnh client-server. Cc trnh

duyt web ng vai tr l client yu cu (request), nhn v hin th cc itng. Server gi cc i tng trong tr li (response).- HTTP s dng kt ni TCP: mt phin giao dch thnh cng ca HTTP c bnphi tri qua 4 bc sau:

Client khi u kt ni TCP ti server, cng 80 Server chp nhn kt ni TCP t client Cc bn tin HTTP trao i gia trnh duyt (HTTP client) v Web server

(HTTP server) ng kt ni TCP


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- HTTP khng hng trng thi: server khng duy tr thng tin v cc yu cuca client trong qu kh.- HTTP c th phn loi thnh Nonpersistent HTTP v persistent HTTP(HTTP/1.1).

2.FTP:- FTP (File Transfer Protocol) l mt dch v cho php ta truyn ti file gia 2my tnh xa dng giao thc TCP/IP. FTP cng l mt ng dng theo m hnhclient-server, ngha l my lm FTP Server s qun l cc kt ni v cung cpdch v tp tin cho cc my trm. Ni tm li, FTP Server thng l mt mytnh phc v cho vic qung b cc tp tin cho users hoc ni cho php ngidng chia s tp tin vi nhng ngi dng khc trn mng.

- My trm mun kt ni FTP Server th phi c Server cp account c y thng tin: a ch my Server (tn hoc a ch IP), username v password.Phn ln cc FTP Server cho php cc my trm kt ni thng qua anonymousaccount (thng c truy cp vi password rng). Cc my trm c th sdng cc lnh ftp tch hp sn trong h iu hnh (hoc nhng phn mmchuyn dng khc) tng tc vi my FTP Server.

3. DNS (h thng qun l tn min):

- L h thng thng dch tn ca cc min sang a ch IP.- Mi my tnh trong mng mun lin lc hay trao i thng tin, d liu chonhau cn phi bit r a ch IP ca nhau. Nu s lng my tnh qu nhiu thvic nh nhng a ch IP ny rt kh khn.- Mi my tnh ngoi a ch IP cn c hostname. i vi con ngi, vic nhtn my d sao cng d dng hn nh a ch IP, nn ngi ta tm cch lm saonh x a ch IP thnh tn my tnh. Sau mt thi gian pht trin, dch v DNS(Domain Name System) ra i.- Dch v DNS hot ng theo m hnh client-server, phn Server phc v tnhay cn gi l Name Server, cn phn Client l trnh phn gii tn Resolver.Name Server cha cc thng tin Database ca DNS, cn Resolver n gin chl cc hm th vin dng to cc truy vn v gi chng n Name Server.DNS c thi hnh nh mt giao thc thuc tng ng dng (Application Layer)trong mng TCP/IP.- DNS l mt c s d liu phn tn, iu ny cho php ngi qun tr cc bqun l d liu ni b thuc phm vi ca h, ng thi d liu ny cng ddng truy cp c trn ton b h thng mng theo m hnh Client-Server.

Hiu sut s dng dch v c tng cng thng qua c ch nhn bn


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(replication) v lu tm (caching). Mt hostname trong domain l s kt hpgia nhng t phn cch nhau bi mt du chm.- V d:

Client mun bit a ch IP ca www.amazon.com, n s tri qua cc bc sau: Client yu cu root server tm com DNS server Client yu cu com DNS server xc nh amazon.com DNS server Client yu cu amazon.com DNS server ly a ch IP cho

www.amazon.com

4.SMTP:- SMTP (Simple Mail Transfer Protocol) l giao thc c cc server dng

chuyn th qua li vi nhau. N cng ging nh vic cc trm bu in chuyncc thng th ca khch hng cho nhau.- u tin ngi dng tng tc vi trnh c th (user agent) son, lu, tmkim v c th ca h. Sau , ngi dng trao cho trnh x l th (mailserver) cc bc th m h mun gi ti ngi dng khc. Mail Server s dnggiao thc SMTP trn TCP chuyn th n Mail Server bn ch. Mail serverbn ch nhn cc th n v t chng vo hp th ca ngi dng bn ch.- SMTP l mt giao thc n gin dng cc k t ASCII 7-bit. Sau khi thit lpkt ni TCP n cng 25 ca my ch (c coi l server), my ngun (ccoi l client) ch nhn kt qu tr v t server. Server khi u cuc i thoibng cch gi mt dng vn bn n client thng bo danh tnh ca n v khnng tip nhn th. Nu server khng c kh nng nhn th ti thi im hinti, client s hy b kt ni v th thit lp li ti kt ni sau. Cn nu serversn sng nhn th, client s thng bo l th t u n v ai s l nginhn. Nu ngi nhn tn ti, server s thng bo cho client tip tc gi th.Sau client gi th v server bo nhn cho th . Sau khi c hai bn hon ttphin truyn nhn, kt ni c ng li.

V d:

Root DNS Servers

com DNS Servers org DNS Servers edu DNS Servers

yahoo.comDNS Servers

amazon.comDNS Servers

k58c.orgDNS Servers

hnue.eduDNS Servers

vietnam.eduDNS Servers


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+ Nhng dng bt u bng C: pha client gi i+ Nhng dng bt u bng S: cu tr li ca serverS: 220 ctu.edu.vn

C: HELO cit.ctu.edu.vn

S: 250 ctu.edu.vn says hello to cit.ctu.edu.vn

C: MAIL FROM:

S: 250 Sender ok

C: RCPT TO:

S: 250 Recipient ok

C: DATA

S: 354 Enter mail, end with "." on a line by itself

C: Subject: Its Xmast!

C: So I hope you a merry Xmas and a happy new year!

C: .

S: 250 Message accepted for delivery

C: QUIT

S: 221 Bye-Bye

- Mc d mail server bn my gi c th kt ni SMTP/TCP trc tip ti mailserver bn my nhn, nhng trong thc t, mt bc th c th i ngang qua vimail gateways trc khi n ch. Cng ging nh my ch, mi mail gateway

cng chy mt mail server. Cng vic ca mail gateway, cng ging nh IPgateway, l lu tm v chuyn pht tip cc bc th ca ngi dng. L docn s dng mail gateways l ngi gi khng mun km trong th a chca my ch, hn na khng chc lc bn gi thit lp kt ni ti bn nhn,user bn nhn bt sn my.

5. POP3:- POP (Post Office Protocol) l giao thc cc client nhn e-mail t cc mailserver thng qua kt ni TCP/IP. POP3 (phin bn th 3) l chun hin ti cagiao thc ny.- Mt phin lm vic theo giao thc POP3 bt u ti user agent. User agentkhi ng mt kt ni TCP n cng 110 ca mail server. Khi kt ni thc hinxong, phin lm vic POP3 s tri qua theo th t ba k: chng thc giao dchd liu cp nht.- K chng thc buc ngi dng thc hin th tc ng nhp bng cch nhpvo 2 lnh sau:USER khai bo tn ngi dng

PASS khai bo mt khu


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- Bo tr ca mail server s l mt trong hai cu sau:OK ( ngha: khai bo ca ngi dng l ng)ERR ( ngha: khai bo ca ngi dng l sai v li gii thch)- Trong k giao dch, ngi dng c th xem danh sch th cha nhn v, nhn

th v v xa th trong hp th ca mnh khi cn thit. Cc lnh m ngi dngthng s dng giao dch vi server l:LIST [] Nu dng LIST khng tham s, server s tr v

ton b danh sch cc th cha nhn. Nu c thams l s th t th c th, server s tr v thng tinca ch bc th thi.

RETR [] Ti l th c s th t v

DELE [] Xa l th c s th t QUIT Hon tt giai on giao dch v hy kt ni TCP

6. Cu trc gi tin HTTP:Khi ngi dng chn xem mt trang web, trnh duyt web s load trang web t Web Server v s dng giao thc HTTP chy trn kt ni TCP. Ging nhSTMP, HTTP cng l mt giao thc hng k t. V ct li, mt thng ipHTTP c khun dng tng qut nh sau:

REQUEST_LINE MESSAGE_HEADER MESSAGE_BODY

Gii thch:- Request line: ch ra y l thng ip yu cu hay tr li. V d: GET/images/logo.png HTTP/1.1 : yu cu ti nguyn /images/logo.png t server.- Header : http nh ngha nhiu kiu header, mt s lien quan n cc thng

ip yu cu, mt s lin quan n cc thng ip tr li v mt s li lin quann phn d liu trong thng ip.- Empty line: Mt hng trng- Message body: phn ni dung ca thng ip. y l phn khng bt buc phi c trong thng ip HTTP, vi thng ip yu cu thng n l rngnhng n li thng c trong thng ip tr li.

Cu 22:Trnh by cc kin trc ca tng ng dng. Ly v d minh ha.


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Cc kin trc ca tng ng dng bao gm:- M hnh Client Server- M hnh peer-to-peer

- M hnh Hybrid

1. M hnh client-server: cu 19

2. M hnh peer-to-peer: cu 19

3.M hnh Hybrid:L m hnh lai gia 2 m hnh client-server v peer-to-peer. Cc tnh cht ca

m hnh ny:- Truyn file theo kiu P2P:

Cc peer ng k ni dung ti server trung tm Cc peer gi yu cu server trung tm xc nh v tr ca ni dung

- Giao tip gia 2 user l P2P- Qun l tp trung v tr ca user:

User ng k a ch IP vi server trung tm khi kt ni User thng qua server trung tm tm a ch IP ca i tng cn giao

tip- V d s dng m hnh ny: dch v chia s m nhc trc tuyn Napster

Cu 24:Trnh by khi nim v vai tr ca Web Cache trong mng ni b.Mt mng ni b c s lng ngi s dng mng l 1000 users, ngi ta sdng mt ng truyn kt ni Internet n ISP l 4Mbps. Hin ti mng ch cth phc v cho 150 connections truy cp web ng thi ra Internet. Hy trnhby cc gii php c th nng cp mng m bo 250 n 300 connectionstruy cp web ng thi ra Internet.

1.Web Cache :- B m web (web cache) l ni lu tr cc vn bn web (cc trang HTML,nh, ) nhm lm gim lu lng mng, gim ti server v gim tr.- Phn loi : c 2 loi Web cache.

B m ca trnh duyt (browser cache) : l mt phn ca mi trnh duyt

web ph bin. N lu tr mt bn copy cc b ca tt c cc trang web


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va c hin th, khi user tr li mt trong cc trang web ny, bn copycc b c ly ra s dng tip.

B m proxy (proxy cache) l mt b phn chia s mng c chc nnggii quyt cc giao tc Web thay cho client, v ging nh b m trnh

duyt, b m proxy lu tr ni dung trang web. Cc yu cu (requests)tip theo ti ni dung ny bi client s c b m proxy cung cp bncopy c lu tr, thay cho vic lp li qu trnh download t ngun.Proxy cache nm gia client v server.

- Tc dng: Gim tr: do cc yu cu c th c p ng ngay t b m thay v

phi gi ti my ch, thi gian ly v hin th cc ni dung thng tinc rt ngn ng k, t s lm trang web c kh nng p ng

nhanh hn. Gim lu lng mng : do cc thng tin c s dng li, lng bng

thng client s dng s gim i. iu ny gip khch hng tit kim chiph khi s dng cch tnh cc theo lu lng, ng thi cng gip gimi hi v mc bng thng.

Cu 25:

Mt mng LAN s dng di a ch IP l 172.16.1.0/24. Hi:- Mng trn s dng lp a ch IP no?- Cn chia mng thnh nhiu mng con (subnet) vi s host ti a l 30 hosts,vy s bits cn mn chia mng l bo nhiu?- Hy thc hin vic chia mng bng cch lit k cc di a ch IP/Subnetmaskca mi mng con (subnet)

1. Mng ny s dng lp a ch B do byte u tin trong a ch l 172 thuc

khong 128 192.

2. S host ti a l 30 hosts > 16 = 24 , < 32 = 25 nn cn dng 5 bits lmHostID. Nh vy cn mn 8 - 5 = 3 bits.

3. Tng s bits lm NetID trong l: 16 + 8 + 3 = 27 (bits)Subnet mask: 255.255.255.224Cc di a ch IP ca subnets:

Mng 1: 172.16.1.0/27 => s host trong khong 172.16.1.1

172.16.1.30Mng 2: 172.16.1.32/27 => s host trong khong 172.16.1.33 172.16.1.62


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Mng 3: 172.16.1.64/27 => s host trong khong 172.16.1.65 172.16.1.94Mng 4: 172.16.1.96/27 => s host trong khong 172.16.1.97 172.16.1.126Mng 5: 172.16.1.128/27 =>s host trong khong 172.16.1.129 172.16.1.158Mng 6: 172.16.1.160/27 =>s host trong khong 172.16.1.161 172.16.1.190

Mng 7: 172.16.1.192/27 =>s host trong khong 172.16.1.193 172.16.1.222Mng 8: 172.16.1.224/27 =>s host trong khong 172.16.1.225 172.16.1.254

Ghi ch:- Da trn cng ca K57C- Trong cu hi cng khng tn ti cu 5

- Cu 15 trng cu 9, cu 16 trng cu 7, cu 17 trng cu 1, cu 18 tng tcu 1 khng lm- Cu 23 (v Socket) b qua khng phi hc (theo li thy)- Phn bi tp v d cu 24 (cu v Web Cache) cn thiu, cha gii quyt c

Nhng ngi thc hin:V Th LuynL Th Thc

V c ThnhBi Th ThuNguyn Hng Vit

MMT DeCuong Final

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