Mang May Tinh

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  1. 1. HC VIN CNG NGH BU CHNH VIN THNG - - - - - - - - - - - - - - SCH HNG DN HC TP MNG MY TNH Bin son : Ts. PHM TH QU Lu hnh ni b H NI - 2006
  2. 2. M U Ti liu ny phc v cho sinh vin h o i hc t xa hc tp v nghin cu v Mng my tnh. Ti liu gm cc ni dung chnh sau: Chng I: Gii thiu tng quan v mng my tnh. Khi nim c bn v kin trc v cc giao thc mng, cc loi mng my tnh v mc tiu ng dng ca n. Chng II: Nghin cu cc nguyn tc c bn thit k mt m hnh giao thc mng my tnh theo quan im chia cc tin trnh truyn thng thnh cu trc nhiu tng, c xp chng ln nhau thc hin mt tin trnh truyn thng hon chnh. Gii thiu m hnh OSI, c xem nh l mt m hnh chun, mt chin lc pht trin cc h thng m v mt khung khi nim v giao thc v dch v. Chng III: Gii thiu mt s b giao thc mng mang tnh c trng v c p dng ph bin. c bit trong chng ny tm hiu su hn b giao thc TCP/IP tr thnh chun chung cho mng my tnh ton cu, mng Internet. Chng IV: Chng ny gii thiu cc cng ngh mng cc b. Kin trc mng cc b Ethrnet, Virtual LAN, Local ATM , LAN ARCnet.. Chng V: Gii thiu v cng ngh v k thut mng din rng WAN. C th xem xt cng ngh cc mng tch hp s a dch v ISDN v bng rng B-ISDN, Frame Relay v X25, dch v SDMS v phng thc truyn dn khng ng b ATM. Chng VI: Gii thiu mt s cng ngh mi nh cng ngh ng dy thu bao s DSL, cc mng chuyn mch gi chuyn ti ting ni trn nn IP, ATM v Frame Raly. Cc cng ngh chuyn mch nhn a giao thc IP/MPLS, chuyn mch mm Softswitch s dng trong mng hi t v mng th h sau NGN. Chng VII: cp n mt s vn bo v thng tin trn mng. Chng ny gii thiu cch tip cn cc h mt m, cc giao thc bo mt, mng ring o VPN v cc gii php an ton mng, xc thc in t, cc gii php ch k in t, xc minh ch k v t chi ch k gi mo.. Ti liu khng ch cp n nhng vn c s l lun m cn trnh by mt s k nng, kinh nghim cn thit thit k v ci t cc mng my tnh. Hy vng s c ch cho cc bn hc sinh sinh vin v nhng ngi mun xy dng cc h thng tin hc ng dng phc v cho sn xut, qun l trong cc doanh nghip. C th cn nhiu thiu st trong trnh by v bin son do kh nng, trnh , nhng ngi bin son mnh dn gii thiu ti liu ny v mong nhn c s gp ca bn c. TS Phm Th Qu
  3. 3. Chng 1: Khi nim v mng my tnh CHNG I: KHI NIM V MNG MY TNH Ni dung ca chng s trnh by cc khi nim c bn ca mng my tnh, nh ngha mng my tnh, mc tiu v ng dng ca mng, cu trc v cc thnh phn c bn ca mt mng my tnh. Cc thc th trn mng c th tham gia truyn thng vi nhau cn tun theo tp cc phn mm iu khin hot ng ca mng, c gi l chun, hay cn gi l tp cc giao thc mng (Protocols). Ni dung ca chng bao gm cc phn sau: nh ngha mng my tnh Mc tiu mng my tnh. Cc dch v mng. Cu trc mng (Topology) Khi nim giao thc mng my tnh (Protocols) Mng LAN, MAN, WAN. Mng chuyn mch knh (Circuit switched Networks) Mng chuyn mch gi (Packet Switched Networks). Cc m hnh x l d liu 1.1. nh ngha mng my tnh Mng my tnh l tp hp cc my tnh n l c kt ni vi nhau bng cc phng tin truyn vt l (Transmission Medium) v theo mt kin trc mng xc nh (Network Architecture). Mng vin thng cng l mng my tnh. Cc node chuyn mch l h thng my tnh c kt ni vi nhau bng cc ng truyn dn v hot ng truyn thng tun theo cc chun m hnh tham chiu OSI. Hnh 1.2 m t khi qut cc thnh phn ca nh ngha. Terminal Cc node mng Printer Hnh 1.1 Mng my tnh 5
  4. 4. Chng 1: Khi nim v mng my tnh Kin trc mng gm cu trc mng (Topology) v giao thc mng (Protocols). Topology l cu trc hnh hc ca cc thc th mng v giao thc mng l tp cc quy tc chun cc thc th hot ng truyn thng phi tun theo. 1.2. Mc tiu mng my tnh 1.2.1. Mc tiu kt ni mng my tnh - Cng chia s cc ti nguyn chung, bt k ngi s dng no cng c quyn khai thc, s dng ti nguyn ca mng m khng ph thuc vo v tr a l ca n. - Nng cao tin cy ca h thng nh kh nng thay th khi mt s thnh phn ca mng xy ra s c k thut th vn duy tr s hot ng bnh thng ca h thng. - To mi trng giao tip gia ngi vi ngi. Chinh phc c khong cch, con ngi c th trao i, tho lun vi nhau cch xa nhau hng nghn km. 1.2.2. Li ch kt ni mng - C th gim s lng my in, a cng v cc thit b khc. Kinh t trong vic u t xy dng cho mt h thng tin hc ca mt c quan, x nghip, doanh nghip... - Dng chung ti nguyn t tin nh my in, phn mm...Trnh d tha d liu, ti nguyn mng. C kh nng t chc v trin khai cc n ln thun li v d dng. - Bo m cc tiu chun thng nht v tnh bo mt, an ton d liu khi nhiu ngi s dng ti cc thit b u cui khc nhau cng lm vic trn cc h c s d liu. Tm li, mc tiu kt ni cc my tnh thnh mng l cung cp cc dch v mng a dng, chia s ti nguyn chung v gim bt cc chi ph v u t trang thit b. 1.3. Cc dch v mng 1.3.1. Cc xu hng pht trin dch v mng my tnh - Cung cp cc dch v truy nhp vo cc ngun thng tin xa khai thc v x l thng tin. Cung cp cc dch v mua bn, giao dch qua mng... - Pht trin cc dch v tng tc gia ngi vi ngi trn phm vi din rng. p ng nhu cu trao i thng tin a dch v, a phng tin. To cc kh nng lm vic theo nhm bng cc dch v th in t, video hi ngh, cha bnh t xa ... - Xu hng pht trin cc dch v gii tr trc tuyn (Online) hin i. Cc hnh thc dch v truyn hnh, nghe nhc, chi game trc tuyn qua mng...... 1.3.2. Cc dch v ph bin trn mng my tnh - Dch v tp (File services) cho php chia s ti nguyn thng tin chung, chuyn giao cc tp d liu t my ny sang my khc. Tm kim thng tin v iu khin truy nhp. Dch v th in t E_Mail (Electronic mail) cung cp cho ngi s dng phng tin trao i, tranh lun bng th in t. Dch v th in t gi thnh h, chuyn pht nhanh, an ton v ni dung c th tch hp cc loi d liu. 6
  5. 5. Chng 1: Khi nim v mng my tnh - Dch v in n: C th dng chung cc my in t tin trn mng. Cung cp kh nng a truy nhp n my in, phc v ng thi cho nhiu nhu cu in khc nhau. Cung cp cc dch v FAX v qun l c cc trang thit b in chuyn dng. - Cc dch v ng dng hng i tng: S dng cc dch v thng ip (Message) lm trung gian tc ng n cc i tng truyn thng. i tng ch bn giao d liu cho tc nhn (Agent) v tc nhn s bn giao d liu cho i tng ch. - Cc dch v ng dng qun tr lung cng vic trong nhm lm vic: nh tuyn cc ti liu in t gia nhng ngi trong nhm. Khi ch k in t c xc nhn trong cc phin giao dch th c th thay th c nhiu tin trnh mi hiu qu v nhanh chng hn. - Dch v c s d liu l dch v ph bin v cc dch v ng dng, l cc ng dng theo m hnh Client/Server. Dch v x l phn tn lu tr d liu phn tn trn mng, ngi dng trong sut v d s dng, p ng cc nhu cu truy nhp ca ngi s dng. 1.4. Cu trc mng (Topology) Topology l cu trc hnh hc khng gian ca mng thc cht l cch b tr v tr vt l cc node v cch thc kt ni chng li vi nhau. C hai kiu cu trc mng: kiu im - im (Point to Point) v kiu qung b (Multi Point). 1.4.1. Kiu im - im (Point to Point) ng truyn ni tng cp node li vi nhau theo mt hnh hc xc nh. Mt knh truyn vt l s c thit lp gia 2 node c nhu cu trao i thng tin. Chc nng cc node trung gian: tip nhn, lu tr tm thi v gi tip thng tin sang node tip theo khi ng truyn ri. Cu trc im- im gi l mng lu v gi tip (Store - and - Forward). u im l t kh nng ng thng tin (Collision). Nhc im ca n l hiu sut s dng ng truyn thp. Chim dng nhiu ti nguyn, tr ln, tiu tn nhiu thi gian thit lp ng truyn v x l ti cc node. V vy tc trao i thng tin thp. Mng hnh sao (Star) Mng chu trnh (Loop) Mng y (Complete) Hnh 1.2 Cc mng c cu trc im - im 7
  6. 6. Chng 1: Khi nim v mng my tnh 1.4.2. Kiu a im hay qung b (Point to Multipoint, Broadcasting) Tt c cc node cng truy nhp chung trn mt ng truyn vt l. Mt thng ip c truyn i t mt node no s c tt c cc node cn li tip nhn v kim tra a ch ch trong thng ip c phi ca n hay khng. Cn thit phi c c ch gii quyt vn ng thng tin (Collision) hay tc nghn thng tin trn ng truyn trong cc mng hnh BUS v hnh RING. Cc mng c cu trc qung b c phn chia thnh hai loi: qung b tnh v qung b ng ph thuc vo vic cp pht ng truyn cho cc node. Trong qung b ng c qung b ng tp trung v qung b ng phn tn. Qung b tnh: Chia thi gian thnh nhiu khong ri rc v dng c ch quay vng (Round Robin) cp pht ng truyn. Cc node c quyn c truy nhp khi n ca thi gian ca n. Qung b ng tp trung: Mt thit b trung gian c chc nng tip nhn yu cu lin lc v cp pht ng truyn cho cc node. Kiu cp pht ny gim c ti a thi gian cht ca ng truyn, hiu sut knh truyn cao, nhng thit k phc tp v kh khn. Qung b ng phn tn: Khng c b trung gian, cc node t quyt nh c nn hay khng nn truy nhp ng truyn, ph thuc vo trng thi ca mng. Mng hnh BUS Mng hnh vng RING V tinh Hnh 1.3 Cc mng c cu trc qung b 1.5. Khi nim giao thc mng my tnh (Protocols) 1.5.1. Khi nim v giao thc Cc thc th ca mng mun trao i thng tin vi nhau phi bt tay, m phn v mt s th tc, quy tc... Cng phi ni chung mt ngn ng. Tp quy tc hi thoi c gi l giao thc mng (Protocols). Cc thnh phn chnh ca mt giao thc bao gm: - C php: nh dng d liu, phng thc m ho v cc mc tn hiu. - Ng ngha: thng tin iu khin, iu khin lu lng v x l li.. Trao i thng tin gia hai thc th c th l trc tip hoc gin tip. Trong hai h thng kt ni im - im, cc thc th c th trao i thng tin trc tip khng c s can thip ca cc thc th trung gian. Trong cu trc qung b, hai thc th trao i d liu vi nhau phi thng qua cc 8
  7. 7. Chng 1: Khi nim v mng my tnh thc th trung gian. Phc tp hn khi cc thc th khng chia s trn cng mt mng chuyn mch, kt ni gin tip phi qua nhiu mng con. 1.5.2. Chc nng giao thc ng gi: Trong qu trnh trao i thng tin, cc gi d liu c thm vo mt s thng tin iu khin, bao gm a ch ngun v a ch ch, m pht hin li, iu khin giao thc... Vic thm thng tin iu khin vo cc gi d liu c gi l qu trnh ng gi (Encapsulation). Bn thu s c thc hin ngc li, thng tin iu khin s c g b khi gi tin c chuyn t tng di ln tng trn. Phn on v hp li: Mng truyn thng ch chp nhn kch thc cc gi d liu c nh. Cc giao thc cc tng thp cn phi ct d liu thnh nhng gi c kch thc quy nh. Qu trnh ny gi l qu trnh phn on. Ngc vi qu trnh phn on bn pht l qu trnh hp li bn thu. D liu phn on cn phi c hp li thnh thng ip thch hp tng ng dng (Application). V vy vn m bo th t cc gi n ch l rt quan trng. Gi d liu trao i gia hai thc th qua giao thc gi l n v giao thc d liu PDU (Protocol Data Unit). iu khin lin kt: Trao i thng tin gia cc thc th c th thc hin theo hai phng thc: hng lin kt (Connection - Oriented) v khng lin kt (Connectionless). Truyn khng lin kt khng yu cu c tin cy cao, khng yu cu cht lng dch v v khng yu cu xc nhn. Ngc li, truyn theo phng thc hng lin kt, yu cu c tin cy cao, m bo cht lng dch v v c xc nhn. Trc khi hai thc th trao i thng tin vi nhau, gia chng mt kt ni c thit lp v sau khi trao i xong, kt ni