Tài liệu Tìm hiểu hệ thống máy chủ cân bằng tải

BQ GLAD DVC VA DAO T$0 TRUONGDS1 HQC MANG LONG KHOA LUAN TOT NGHIEP DE TAI: TIM HIEU HE THONG MAY CHU CAN BANG TAI Ciao vien hirfrng gin Sinh vien thyc hien Ma sinh vien Chuyen ngInh Ts.Pham Thanh Giang DO Van Thinh A13439 CONG NGHt THONG TIN HA NQI — 2013 This is trial version www.adultpdf.com 2 MAY CHU CAN BANG TAI CHUONG 1: GICII THIEU 1.1. Su cant thiet cita can bang tai 1.1.1. Mei trubng may chit 1.1.2. Mei truong mung 1.2. Can bang tai: dinh nshia vi img dung 13. Cac san pharn can bang tai CHUONG 2: MAY CHU CAN BANG TM 2.1. Tong quan 2.2. Luan chuyen yang DNS , 2.3. Cum may chit yeti be can bang tii 2.4. Lueng WA tin ca ban trong can bang tii 2.5. Kiem tra tinh tang sire khoe 2.5.1. Clic quit trinh Idem tra ca ban 2.5.2. Clic cuec kiem tra tren the img dung cu the 2.5.3. Su php thueac via img dung 2.5.4. Kjch Bin 2.5.5. Kat Luon 2.6. Djch dja chi mpg (NAT) 2.6.1. NAT dfch 2.6.2. NAT ngwin 2.6.3. NAT nguqc 2.6.4. NAT nang cao (Enhanced NAT) 2.6.5. Djch dja chi ding (PAT) 2.7. Tritiai tir may chit trvt tiep (Direct Server Return - DSR) CHUONG 3: THUAT TOAN CAN BANG TM 3.1. Nei dung Ichai quit 3.2. Geri thieu met se thuot man can bang tai 3.2.1. Thuat town Round Robin 3.2.2. Thuat toin Weighted Round Robin 3.2.3. Thuat toan Least Connection 3.2.4. Thuet town Weighted Least Connection CHUONG 4: THIET ICE MANG yen Bo CAN BANG TM tuyen 4.1. BO canI bit, tai Whir la met be chuyen mach so yeti met be dinh 4.2. Cac thiet ke don gian 4.3. Thiet ke cho tinh sin sing cao 4.3.1. Active - Standby 4.3.2. Active - Active 4.3.3. Chuyen dei du phi:mg co tang thai 4.3.4. Da dja chi VIP 4.3.5. Quit trinh khei phuc b0 can bang tai 4.3.6. Toy chip thiet ke tinh sin sang cao 4.3.7. Su ciao tiep gill, ate b0 can brill tii CHUONG 5: CAU HINH CAI EMT VA THU. NGHIEM 5.1. Gi6i thieu 5.2. Tong quan HAProxy 5.3. Cid dirt gilt phip HAProxy cho may chit Web tren CentOS This is trial version www.adultpdf.com 6 6 7 7 8 9 11 11 11 15 19 22 22 23 23 24 24 25 25 25 28 28 29 30 32 32 33 33 34 34 35 35 38 39 40 42 45 46 47 47 56 58 58 58 59 3 5.3.1. Thiet ice h" tilting 5.3.2. Hoat dOng 5.4. CM dat eau hinh 5.4.1. CM dat du hinh HAProxy 5.4.2. Cal dat dich vn WebServer tren Server 1 va Server 2 5.4.3. CM dat vit c.4u hinh KeepAlived tren Haproxy, Server 1, Server 2 5.5. Kiem tra & Danh gia ket quit TONG !CET DANH MVC TAI Lieu THAM MAO This is trial version www.adultpdf.com 59 60 60 60 61 62 65 70 71 4 Tir vih tat "lir Day dii OSI MAC ISP HTTP FTP SMTP DNS NFS URL TCP UDP IP VIP ARP RTSP STP VRRP SSL NAT PAT DSR CPU VLAN RS Open Systems Interconnection Media Access Control Internet Service Provider Hypertext Transfer Protocol File Transfer Protocol Simple Mail Transfer Protocol Domain Name System Network File System Uniform Resource Locator Transmission Control Protocol User Datagram Protocol Internet Protocol Virtual Internet Protocol Address Resolution Protocol Real Time Streaming Protocol Spanning Tree Protocol Virtual Router Redundancy Protocol Secure Sockets Layer Network Address Translation Port Address Translation Direct Server Return Central Processing Unit Virtual Local Area Network Real Server Giai ngltia MO hinh ket not cac he thong ma Kiem soat truy cop phuang tien Nha cung cap dich vp Internet Giao that truyen tai sieu van ban Giao thin truyen tai teP tin Giao thin truyen tai thu don gian He thOng phan giii ten mien He thOng tep tin mang Dinh vi thong nhat tai nguyen Giao thirc dieu khien truyen Van Giao thin gai tin ngtroi dimg Dia chi giao thin mang Dia chi giao thirc mang ao Giao thirc phan giai dia chi Giao that trvc tuyen then gian thvc Giao thin ma rOng cay Giao thin du phong dinh tuyen ao Giao thirc lap mot ma Dich dia chi mpg Dich dia chi ding Quay troy bye tiep may chit Don vi xir 19 trung tarn Mang cvc bt) ao May chit thvc This is trial version www.adultpdf.com 5 Chuang 1: GU% thieu DO Van Minh - A13439 CHUONG 1: GIOI THItU Ngay nay can bang tai khong con la met khai niem meri trong khong gian mang va may chit. Moi loai san phim thuong thgc hien cac cons viec lchac nhau trong qua trinh can ban! tai. Vi du, cac 110 djnh tuyen do the phan phoi luu lucmg truy cap th8ng qua Mien tuyen duerng de den cling met dia chi dich vi can bang tai ten cac tai nguyen mang khac nhau. Trong khi di met may chi can bang tai phan phoi luu 'wing giera cac tai nguyen may chi chi khong phai la cac tai nguyen mang. Ban dAu be can bang tai bit du veri qua With can bing tai don gian, chimg nhanh chOng duqc phat trien de thgc hien met bat cac chic nang: can . bAng tai, Icy thu#t phan ph& luu Itrqngt chuyen mash lugng thong minh. Be can bang tai cling c6 the thuc hien cac cuOc kiem tra sic khoe met cach tinh vi ten cac may chii, cac ing dung, va ca nOi dung de cai thien firth sin sang va Ich# Wing quan IS,. Bei vi b0 can bang tai dugc trien khai nhu met may chit tiep nh#n you cau cult met nhim cac may chii, chting cling bao ve cac may chi ti ngueri ding dec hai, va tang cuang kha nang an ninh bao mat. Dtra‘ tren th8ng tin trong cac g6i tin IP hoac nei dung trong cac you cau ing dung, be can bang tai Qua ra cac quyet dinh thong minh de dinh huang cac luu Wang thich hqp den ding trung tam de lieu, may chi, tiring lira, b0 nher cache, hoac img dung. De tai nay se tap trung nghien ciru tong quan ve may chi can bing tai, cach thic hot dOng cia be can bang tai trong Wan be he thong mang, tir d6 img dung tren dux to trien Mud be, can bang tai tren toan b0 he thOng met cach hieu qua va (tat dugc hieu suit tot nhat. De tai se dtra ra met m8 hinh cu the, ap dung thu#t toan di chqn Itra de dtra ra cach nhin re hon ve yin de thing to dang Wang teri. 1.1. Sr can fillet cia can bing tai CO hai xu huortg clan den sy can thiet cia can bang di lit may chi va mang. Veri st ir vtrgt trei dm Internet va Intranet, ket not mang giita may chi va may tinh ca nhan cia !than vien, khach hang hoac nha cung img di trer titbit 'diem vu quan trong. se khong the chap flan dirge khi mang bi sap hay the hien kha nang lam viec yeu kern, khi d6 no hau nhu se tri tre moi host &Ong kinh doanh trong nen kinh to dua nhieu vkInternet. MOt vi du nhu xay dtmg met website thuong mai Bien tir, c6 rat nhieu be phan can dugc xem xet nhu la: b0 djnh tuyen, be chuyen mach, Wang lia , be the dem, may chi web, may chit ca ser cla lieu. Hon Ilea viec gia tang nhanh cia ck may chi cho hang lost cac img dung di kW& cho trung tan.' dit lieu day ip cac cum may chi. Su r6i ram va thach thirc trong khit nang nier rOng, kha nang quart ly va khit tiling sin sang cia cia cac nhim may chi la met nhin to dimg ding sau den hei can ci met su thay doi thong minh. Met thir ma .n8 phai chic chin ve kha nang mer reng va firth sin sang cao cho mgi thanh phan, bat dau tir be dirt tuyen ket not voi Internet, cho to; tat ca cac con dutng teri may chi de lieu ben trong. Tir di thiet bi can bang tai St hien nhu la met vu khi mang me de xi ly nheng van de tren. This is trial version www.adultpdf.com 6 Chuang 1: Gi6i thieu DS Van Thinh — A13439 1.1.1. Mai trwang may chu Sp phat trien manh me cea may chti trong cac doanh nghiep ngiy nay va viec cung cap dich vu Internet (ISP) xuat phat tir hai do chink. Tar& het, co rat nhieu cac Img dung hay dich vu can den trong k9 nguyen dm Internet nhu Web, FTP, DNS, NFS, Email, database, ... Tha hai, rat nhieu img dung deli hai can co nhieu may chu cho moi ling dung bed vi met may chit khong the cung cap MI sirc mph hay !chit nang de dux wen cac you cdu ctia Ung dung do. Nei chuyen v6i bat dr met ngueri nao lam viec von hanh trong tam dii lieu, he) se cho ban biet can bao nhieu thin gian de xix 19 nhang van de ve kha nang quan 19, kha nang ma rOng va tinh skin sang dm nhieu loci img dung tren cac may chti. Vi du, neu met tiring dung email lchting the xi: 19 st ir tang len ye nguiri dung, met may clui mail se duqc bo xung trien khai them. Ngutri vim ly cling phai nghi cach de phan tai gitta hai may cliff nay. Neu met may chi' gap van de, ngueri quin trj ngay luc de phai chay ung dung ten met may chif khic trong khi may chit van de duqc sin chila. Khi no da dugc sin xong, no phai dua ter lai de phuc vu. Tat Tatca nhftng nhiem vu do inh huerng tai tinh skin sang va hieu qua dm CEng dung d6 deli v6i ngtreri &mg. ve kha ?long ma rang: van de ve quy me ding suet may tinh khong con la mai. Tn.rerc day, met may chti duqc clanh de chay met img dung. Neu may chii de khong hoan thanh nhiem vu, thay vac) de met may chit mph han se dugc mu, meri. Stic manh cua cum may chi' tang len khi tong bo ph#n khic nhau trong town he thong tra len manh me han. Vi du, chung ta da thay toc do elm be xti 19 duce Ling gap deli cu sau mai 18 thang - met hien Wong ngly nay dirge biet tai nhu la luOt clia Moore, dOt theo ten dui Gordon Moore dm top doan Intel. Nhtmg nhu eau sir dung may tinh tang thorn chi con nhanh han. Gong nghe cum (clustering) do de da dugc phat mink Thech thzec 1.1.2. Mai truirng mgng Thiet bi chuyen mach truyen thong va be dint' tuyen host dOng tren dja chi IP hoac dia chi MAC de xac djnh diem den curt gel tin, tuy nhi 'en, chimg kh8ng the xi: 19 cac nhu cern dm cac cum may chti phtirc hop hien du. Vi du, cac be dinh tuyen hoac b0 chuyen mach khong the thong minh khi girl ltru luong truy cop den met may chit cu the hoOc be nher cache. Neu met may chil dang bj hang, thiet b1 chuyen mach truyen thong yin tiep tuc gfri Iuu Itrqng truy cop vim melt may chi' da chet, de hieu dugc chirc nang ctia HU& N chuyen mach vi thiet 111 (firth tuyen truyen thong thi dau tien chung ta phai kiem tra m8 hinh mang OSI. This is trial version www.adultpdf.com 7 Chuang 1: Gieri thi0 DO Van Minh — A13439 Layer 7 Application Layer Layer 6 Presentation Layer Layer S Session Layer Layer 4 Transport Layer TCP. UDP Lam 3 Network Layer IP Layer 2 Data Link Layer Layer Physical Layer IITIR F17. SNMP. Telnet. DNS Hinh 1.1: so tla ma hinh MO hinh OSI la mOt tieu chitin ma de xac djnh Mm the nao ma cac thiet bj hoc may tinh khac nhau co the giao tiep dugc yeti nhau. N6 bao gtim 7 tang, Ur tang vat 1S7 den tang (rug dung tuang Mfg vai cac tang la cac giao thfrc ph6 bien. BO chuyen mach va b0 djnh tuyen lam viec a lap 2 va 16.p 3, se xac dinh mOt gei tin phai duqc xir IS , nhu the nao va not ma gei tin phai &gm girl dua tren !hong tin trong phan header. Tuy nhien chang to se khong di qua sou vao m8 hinh trong de tai nay. 1.2. Can bing dinh nglifit va frng dying VOi su ra dai dm Internet, mang hien nay hien chiEm san khau trung tam. IChi ma Internet ket not the gith vOi mang b0 ne se ter thank xucmg song hour dOng cho cac doanh nghiep, lac nay co se hu tang cling nghe thong tin ce the duce coi nhu la hat loai thiet bj: may firth ce chat Ming nhu may khich/ hoc may clth, thiet bj chuyen mach/ b0 djnh tuyen kEt not cac may tinh. BO can bang tai la eau n6i gifts cac may cho vi mang. dirge the hien ton§ hinh. Mitt mitt, bel can bing tai hieu nhieu giao thirc lop cao hon, do de ne c6 the giao tiep vai cac may chil thong minh. Mat khac, bij can bang tai hieu cac giao thine mang, do d6 n6 co the tich hap yen cac mang khic mOt each hieu qua. Hinh 1.2: cam may cho vari ba can bang tai This is trial version www.adultpdf.com 8 Chuong 1: Giai thieu D6 Van Thinh - A13439 Can bang tai dirge img dung trong rat nhieu twang hap nhu • Can bang tai may chit (Server load balancing) • Can bang tai may chit town cau (Global server load balancing) • Can bang tai tubing lira (Firewall load balacing) • Chuyen mach be nha cache (Transparent cache switching) • Can bang tai tren &rang truyen Internet (Load Balancing with multi wan and failover) • ... Can bang tai may chti xir ljr v&i viec phan chia tai theo cac may chit (multiple servers), quy m6 hea trong kha nang litm viec cita timg may chit va dam bao kha nang chit' dung khi met may chit nao de khong host clang. Can bang may chti tat town cau xir l5r viec htrang ngu&i dung truy cap tai nhung diem khac nhau not dat trung tam du lieu, bao grim cac cum may chit c6 kha Ong cung 1mg cho ngtrai dung thai gian phan hei nhanh nhat c6 the va chili dung khi met trung da lieu mat kha nang lam viec. Can bang tai twang hia phan phei tai qua cac twang lira (multiple firewalls), quy mo hoa trong kha nang cita tong tubing lira vi dam bio kha nang chili dung khi met tubng lira mat kha nang lam viec hoan town. Chuyen mach 60 nha cache la Wang ltru lugng fly cop den cac cache de tang tee theri gian dip thig cho khich hang hoac cai thien hieu sat cim cac may chit Web bang viec tai cac net dung tinh dua den cac cache. Can bang tat tren (twang truAn Internet la giii phip &up tang bang th8ng co sin do ca kha nang sir dung deng thtri nhieu lien kat. NO cung cap can bang tai cho cac nha cung cap dich vu khic nhau va cho cac ket not wan bang viec tOng slicip va tao dieu kien gitip tang kha nang 161 cho mpg dien renf thong qua chuyen doi du phOng. Do d6. cac ket not Internet duqc bao dim an Wan, ket not On dinh vol ben ngoii va dam bio chat 'mpg dang tin city trong truyen din. 1.3. Cic san phfim can bAng tai Cac san phim can bang tai co sin duch nhieu hinh thirc khac nhau. Chung co the duck phan chia thanh ba loai: sin pham phan mem, thiet bj, vi thiet bi chuyen mach. Phan mieu to ciia 3 loai theo sau dual day: • Phan main can bang tdi la phan mem chat' tren ck may chit to can bang tai, Slang phan mem nay thuc hien cac thuat toin di dieu phial quit trinh phfin phoi tai. This is trial version www.adultpdf.com 9 Chuang 1: Gith thieu DO Van Thinh - A13439 • That 14 can bAng tai IA dm phAm hOp den bao gem phAn ming NM phan mem an duet de thvc hien nhiem vu. HOP c6 the don gian nhu met may tinh hoac met may chi, dugc dang gal yeti met s6 hg dieu hint' va phan mem dac bigt hoac met hOp dee quyen vOi phan cling vA phan mem tay chink. • Thiit bf chuyin much ma rOng cac chile nang cim mot lap truyen thong (16p 2/3) chuyen dei thAnh cac 16p cao hon bang cach sir dung met so phan cling va phan mem. This is trial version www.adultpdf.com 10 Chuang 2: May chic can bang tai DO Van Thjnh - A13439 CHIANG 2: MAY CHU CAN BANG TAI 2.1. Ding quan Ngay nay may chit can bang tai khong con la mOt khai niern mai trong the gieri may chit. Ck Gong nghe dun may chit da duqc phat minh d'e c6 the thus hien cac uhiem vu tinh toan, nhung lei chi c6duqc thitnh ding trong mOt s8 it cac th8ng dOc quyen. Tuy nhien can bang tai da xuat hien nhu mOt giii phitp mph me clanh cho cac img dung chinh cung nhtr giai quyet cac van de cho timg khu Arc , ne bao gom lcha ndng mer rOng cac nham may chit, tinh san sang, !chit Wins bao mat va khi ndng %Wit ly, not each khk can bang tai la mOt phucmg pluip phan phoi khOi luqng tai tren nhieu may tinh hoac mOt cum may tinh de c6 the sir dung t6i uu cac ngurin lye, tOi da hOa thong lucmg, giam theri gian dap ting va tranh firth trong qua tai tren may chit. Cac lqi ich khi sir dung phucmg phip can bang tai: nto Tang khd ndng ddp itng rPng cai thin clang ke kha ndng ma rOng vita mOt ting dung hoac nhem cac may chit bang each phan ph6i tai th8ng qua cac may chit dam bio firth firth host va ma rung cho he th8ng. Tang 60 tin cPy link sin sing gitip tang grill sin sang cao (High Availability) cho he thing, bed vi n6 co the dinh huemg cac Itru luqng truy cop den cac may chit thay the neu mOt may chit hoc Ung dung kh8ng the dap img dirge d6ng thin dim bao cho ngtrai dung khong bj gian down dich vu khi xay ra l6i str c6 loi tat mOt diem cung cap djch vu. Cdi thin khd ndng quits iy theo nhieu each thirc thong qua viec cho phop nhimg ngtrai quan trj mang va may chit chuyen cac img dung tir mot may chit nay den mOt may chit khac hoac c6 the them nhieu may chit de chay the ang dung nhanh nhat Tang link bdo mPt cho he lung, thong thuang khi ngueri dung giri you au djch vu den hg thong, zyeu au do se duce xir tren boa can bang sau de phin can bang tai mai chuyen tiep cac you eau cho cac may chit ben trong. Qua trinh tra lai cho khach hang ding thong qua thinh phin can bang tai, vi voy ma ngtrai dung khong the Wit duqc chinh xac cac may chit ben trong ding nhtr phuang ?hap phan tai dugc sit dung. Bang each nay c6 the nglin chan ngu&i dimg giao tiep (rut tiep veri cac may chit, an cac thong tin va cau trite mpg nOi b0, ngan ngua cac cuOc tan cling tren mang hoc cac djch vu khong lien quan dang hoot &Ong tren cac ding khk. 2.2. Luan chuyen Wong DNS This is trial version www.adultpdf.com 11 Chuang 2: May chit can bang tai DO Van Thjnh - A13439 De can bang tit may chit, he th8ng an phai phan. phiii ck yeu a u den nhieu may chitit khac nhau ben trong ctun may cho, vii mix dich toi uu h6a hieu suit he thong. Dieu nay se mang den cho mang hieu suit cao han, khi nang ma reng, tranh rat vao tinh trong tong thieu tit nguyen mang trong met doanh nghiep hay met img dung nao do. Tinh sin sang cao co the dtrqc hieu 11 firth trong du thira. Neu met may chit Ichong the plan 19 met you cau thi .cic may chit khac ton* cum may chti do co quart 19 di:cc ne khong? Trong met th6ng c6 !chi nitng‘ cung cap cao, net met may chit bi thi may chd khac se tiep quin ngay dezir 19 yeu cau. Kha nang ma reng dm met *rig dung ce the 118 trq duqc so lucmg ngueri ngly met tang. Neu no can 10ms de met img dung co the dip Uzi cho met yeu cau thi khoang th6i gian se la bao lau de n6 dap tra den 10.000 yeu cau cling met Mc? Kha nang ma reng v8 hurt se cho phdp no dap tra ck you cau nay chi trong khoing 10ms. Kha nang ma reng la don vi do cho met lost cac he' so nhu so Itrqng ngubi dimg dung thtri ma met cum may chtl c6 the h43 trq va thbi gian no can de xir 19 met you au. Frau het chung to co le deu da biet rang, DNS ban di\ h6a ten host thanh ck ilia chi IP. Ngubi dung nhip wwwkoircom vio hitp tha chi cite trinh &wet web Web Bravest Cho UN met Oa chi IP cOa Database www.kok.com DNS Sena web Dro'neer Dia chi P cua www.koiccom 222 255.31 160 Database DNS Saver GET 222 255 31.160 Web Stores web &o'er Hinh 2.1 qua trinh chuyin deli host thanh Ma chi This is trial version www.adultpdf.com 12 Chuang 2: May chi' can bang tai Da Van Thjnh — A13439 Khi nhap mot URL vao trong trinh duy (vi du ram www.kok.com ) thi trinh duyet se giri mot yeu cau den DNS yeu cau no tra ve dja chi IP dm site. Day dugc goi 11 viec tra ciru DNS. Sau khi trinh duyet Web co dugc dja chi IP cho site thi ne se lien he yeti site bang dja chi IP, vi hien thi trang vim yeu cau. May cha DNS thubng co mot dja chi IP dugc ban do boa yeti mot ten site nlo d6. Trong vi du thi site la www.kok.com ban do hos thanh dja chi IP la 222.255.31.160. De can bin tai bang DNS, may chii DNS phai duy trinh mot s6 dja chi IP khac nhau cho cling mot ten site. INThieu dja chi IP the hien nhieu may trong mot emu may chia, tat ca trong so chung deu dugc ban do hem den mot ten site logic. Trong vi du, www.kok.com c6 the dugc cau hinh tren ba may cha trong mot cum may cha yen cac dja chi IP dual day: 222.255.31.160 222.255.31.161 222.255.31.162 Trong trutmg hop nay, may chi) DNS dugc ban do hea nhu sau: www.kok.com 222.255.31.160 www.kok.com 222.255.31.161 www.kok.com 222.255.31.162 auster 222.255.31.160 www.kok.com 222.255.31.161 Luan chuyon Ana DNS 222.255.31.162 Hinh 2.2: Luein chuyin yang DNS Khi yeu au diu tien den dugc may chi' DNS, no se tra V& dja chi IP 222.255.31.160, may dau tien. Khi c6 yeu cau thir hai, n6 se tra ve dja chi IP this hai: 222.255.31.161. Tiip tic nhu vay, veri yeu eau thli tu, dja chi IP diu tien lai dugc lap lai. This is trial version www.adultpdf.com 13 Chuang 2: May chit can bang tai 06 Van Thjnh — A13439 Bang each sir dung luan chuyen wing DNS nhu a tren, tat ca cac you cau dot yeti mot site nao do deu &me phan phot i deu den tat ca cac may trong cum may chit (cluster server). Chinh vi vay, vai phuong phap can bang tai nay, tat ca the may chit trong cum may chit deu duqc sir clung. diim chink ctia phuong plulp a - Khong dit vi ding thiet lip: Cac quan tri vien hg thiing chi can tao mot se thay dot trong may chit DNS de hi!, trq duqc viec luan chuyen yang, va nhieu may chit DNS da co stir ho trq nay. N6 thong you cau den stir thay del ma cita (mg dung Web; trong that te, cac (mg dung Web khong he biet ye co the can bang tai ma no hi that hien. - Don gian: Phuong phap nay khong yeu cau den the chuyen gia ye mpg trong vik thiet lap hoac gia r6i he thong trong twang hqp co van de nao de xay ra. Nhuvc dam min phweng phdp Co hat nhuqc diem chinh cart phuong phap dtra tren phin mem nay la no thong cung cap sr ht!) trq m8i quan hg thai gian that gifta the may chit veri nhau va khong ht) trq Icha nang co sin cao. - Khong ht3 trq m6i quan hc. thai gian that gitka cac may chit. MOi quan hg thin gian that gift cac may chit la kith nang cita he thong trong viec quart 1Sr cac yeu cau cita nguiri dung, may chit nay hok bat kt may chit nao, phu thuOc vio th6ng tin phial .' duqc duy tri tren may chit hoac tai mire co sit, mac co sit dft - Khong co duqc kha nang ht!) trq mei quan he gift cac may chit, phuang phap loan chuyen yang DNS dtra vio mot trong ba phuong phap de duqc dtra ra de duy tri sit kiem soat cac phial hoc sit nhan clang nguoi clang 461 yea cac you cau dang den ten HTTP. • Cac cookie • Cac trutmg An • viEt URL Khi mot nguai dung dux hien mot yeu cau dAu tien, may chit Web se tra mot the bang van bin duy nhit de phan biet nguai dang do. Cac you cau tiep theo co the nay de sir dung cookie, viet 10 URL hoc cac truang An, cho phdp may chit xuat hien de duy tri mot phien glen may khich vi may chit. Khi nguai dimg duet lop mot phien veri mot may chit, thi tat ca cac yeu cau den sau thuang deu di den cling mot may chit. Van de a day la trinh duyet luu dia chi IP cart may chit do. Khi Cache het han, trinh duyet se that hien mot yeu cau khac din voi may chit DNS de co duqc dia chi IP co lien ket yen ten mien. Neu may chit DNS tra ye mot dia chi IP khac, mot may chit khac trong cum may chit, thi cac th8ng tin ye phien se bi mat. This is trial version www.adultpdf.com 14 Chuang 2: May chit can bang tai DO Van Thjnh — A13439 - IChong ha trq cho kha nang c6 san cao. Xem xet met gun may chit co n may. Neu met may chit nao d6 gap van de ye stir co (vi dy la may chit thir n) thi cu yeu au thin n den may chit DNS deu huemg yeu au din may chit hong nay. MOt be djnh tuyen thong minh co the giai guy& duqc van de nay bang cach kiem tra cac may chit 6 cac khoang uteri gian nao do, phat hien ra cac may chti bj h6ng vi ger b6 chimg ra Ichoi danh sach, chinh vi vAy se khong co yeu cAu nao duqc gfri den chting nits. Tuy 4y, van de a day van ton tsi neu may chili van c6 nhung Cling dung Web dang chay tren may chit eta bj hang. Thay dot cum may chit se mat nhieu thiri pian de truyen bi den toan be plan con lai cita Internet. MOt IY do 6 day la trong nhieu to chirc tern — cac ISP, cac cong ty, hay dui ly — hru cac you au DNS dm hp de giam Itru luqng mang va thai gian you au. Khi ngtreri dimg ben trong cac t6 chirc nhu v0y thuc hien met yeu au thi hg thong se duqc kiem tra danh sach cac ten DNS cita Cache da duqc ban do h6a (Ha chi IP. Neu hg th8ng phat hign thiy met muc nao thi no se tra dja chi IP ve cho ngueri dimg. Neu no kh8ng phat hien thay muc nao trong cache nei be thi ISP se giri yeu cau DNS nay den may chit DNS vi km sr dap tra. Khi met muc da duqc luu het hen, ISP se nang cap ca so da ligu n6i be dm no bang ach lien he voi cac may chit DNS khk. Khi danh sach cac may chit thay dai, no c6 the can den met Ichoang uteri gian ngin cho cac muc da duqc Iuu tren mang cita ac to chat khic het han va tim kiem danh sach cac may chti da duce cop nh#t. Trong su6't chu trinh nay, may khach van co the thuc hien hanh deng " Hit " may chit 1)1 hang, neu ISP cita may khach do van c6 met mix tr6 den no. Trong twang hcq? nhu 4y, met so ngueri dimg cita ISP d6 khong the truy c#p tir nhemg lin truy c$p ban dliu, tit* tri hien tai cum may chit van con cac may chit du thira van dang host deng. Met van de con Ion han xuat hien khi ger be met may chit so veri viec ba sung. Khi bat di met may chit, ngueri dung co the dang thuc hien " Hit " met may chit khong ton tsi. Con khi them met may chit thi may chit de van chtra duqc sir dung cho toi khi dja chi IP cita n6 den duqc tat ca cac may chit DNS. Mac clit phuong phip nay c6 the can bang ducc met s6 lircong ngutri dimg tren mai may chit, nhung n6 kh8ng hoin toan can bang tai may chit. Met so ngued dimg co the you au mirc tai cao han trong suot met phien cita hp so veri nhang ngtrai dung khic a tren may chit khic, vi phtrcmg phap nay khong the bao dam chang lai duqc sit bat cong bing do. 2.3. Cym may chit voti bt, can bing tai Met vii nha quin tri may chit se trien khai nhieu may chit de dam bao muc dich tang tinh san sang vi kha nang mer ding. Neu met may chit nao do gap phiti van de kh8ng the dap *rig duqc nhu au, ngay 10p tire met may chti khic cet the duqc mua trong khi may chit gap van de se trong qui trinh sira chaa. Tnrerc khi cac sin phan can pang tai duce phat minh thi DNS thutrng duqc sir dung de phew ph8i tai thong qua nhieu may chit. Vi du, This is trial version www.adultpdf.com 15 Chuang 2: May chit can bang tai DO Van Thjnh — A13439 DNS quan IS, dja chi www.kok.com c6 the dirge cau hinh yeti hat hoac nhieu dja chi IP cho site www.kok.com DNS sau d6 c6 the cung cap mOt trong cac dia chi IP da ductc cau hinh bang cich lam chuyen yang cho mot truy van DNS. Day mei chi la sv hob thanh the,' scr oh qua trinh can bang tai, cach tiep cjn nay can bj giOi hart trong nhieu van de khac. DNS khong the biet duqc kha nang tai va firth trang cim mOt may chit. N6 co the cung cap dia chi IP cim mOt may chit ngay ca khi may chit nay dang gap van de. Bo can bang tits xuat hien va duqc trial khai tnretc nhOm may chit, tat ca cac may chit nay hoac trvc tiep ket not yeti can bang tai hoac ket not thong qua b0 chuyen mach, b0 can bang tai chay dvc theo cvm cac may chit xuAt hien nhu mOt may chit a° di den cac may khach. Cling nhu la may chit that may chit ?to phii co dia chi IP cho cac may may khach truy cap vao n6, day &gm goi la dia chi IP ao (Virtual IP - VIP ). Dia chi IP ao dirge cau hinh tren b0 can bang tai va dai dien cho toan b0 nh6m may chit ben trong. Rtal %PMI'S Memo Sinn 1111 ■ 102.121.10.1 ars 1.00d Man 1 16.2 11110102 11kb WM ItS3: 1010103 SMIP Hinh 2.3: nhom may chit yogi ba can bang tai De truy cap (mg dvng tren cac may chit, dja chi may may khach phai you cau den VIP. Trong truing hqp cita vi dv trang web www.kok.com , DNS phiti sauce cau hinh tra lei VIP gi6ng nhu dja chi IP www.kok.com . Dieu nay cho tat ca cac trinh duyet cita may khach girl yeu cau teri cac VIP thay vi mOt may chit thvc. BO can bang tai nhan dirqc you cau beri vi n6 so hau VIP va phan phoi chimg qua cac may chit thvc sit c6 an. Khd hang mi ring: Ben vi can bang tai phan phoi cac you au dm may khach thong qua tat ca cac may chit thvc sari c6 vi the cong suet zit ly dm may chit Ito cling lem hen Ming suet cita mOt may chit. BO can bang tai sir ding mOt thuat toan phan phoi tai de phan phoi den dm yeu cau cua timg may Ichich. Neu thuat toan toi tru, kha nang nang cita may chit ao se bang ming suit Ping hqp dm tat ca cac may chit thvc. Nhung truing hqp nay la rat hiem do mOt so yeu t8 bao gom ca hieu qua phan ph8i tai. Tuy nhien ngay ca khi ding This is trial version www.adultpdf.com 16 Chuang 2: May chit can bang tai DO Van Thjnh - A13439 suit dm may chit ao dat khoang 80-90% ding suit tong hop cita tat ca cac may chit Sic thi dieu nay cling dg cung cap kha tiling ma tong that tuyet vet Tann sin sang: BO can bang tai lien tic theo dei tinh trong ctia cac may ,cha,thoc va cac ling don chay tren chimg. Neu mot may chit thoc hoacimg ding gap van d'e kh8ng dap Ong ducifc yeu cau, b0 ram bang tai tranh gut batukY yeu ca cita may khach den may chit de. Mac di" bat cir mot so ket not hok cac you cau dang &roc xir 1S , khi mot may chit dang gap yin de thi b0 can bang tai van se dj enh Wong tat ca cac yeu cau den mot trong so cac may chit c6 tinh tang kit& manh. Neu khong co bo can bang tai, ngulyi ta phai doa tren mot c8ng co giam sat mang de kiem tra tinh tang cua mot may chit hoac ling ding, va chuyen huOng may khach den mot may chi) thoc khac. BOA vi 130 can bang tai thoc hien ding vi'ec nay mot cac nhanh chong nen thoi gian chat ducic giam thieu ding ke. mot khi may cha bj 16i dtroc sua chea, b0 can bang tai se phat hien so thay dOi vi bat diu chuyen tiep you cau den may chit. , Khd ming van /57: Neu phan ding cua mot may chit can duce ang cap, hok hg diau hanh, hoac ling ding phan mem ctia no phiti nang cap len mot phiety ban men, may chti serhai dimg hoot dOng. Mac do viec nano cap nay co the duqc sap xep vilo gib cao diem de gram thieu tic (tong cua that gian chet vi se co mot vii doanh nghiep kh8ng ce co du kha nang dank cho khoang thai gian chet nay. MOt s6 doanh nghiep thin w con khong the tim thay bat ky thai gian nap ngoai gib cao diem, dac biet la neu may cha dugc truy cop bed nguOi dung tren town the gieri trong nhftng mui gib khac nhau. Bang cach trien khai b0 can bang tai, chting ta co the ngimg may chit can bao tri ma kh8ng phai chill bit cir thai gian chat nao. Ck can bang tai se thoc hien mot cach khdo leo viec tat may chit, theo d6 can bing tai se dung dua ra yeu cau meri voi may chit d6 va cho dqi cho den khi bit Ick mot ket not hien c6 cham dirt. MOt khi tat ca cac ket not hien c6 duce dang 10, may chit co. the an town ngimg lam viec de bao tri. Vic nay dim bito may khkh kh8ng he hay Wet va bo can bang tai se tiep toe phoc vi cac yeu cau gin den den dja chi IP ao bang cach phan phoi chimg qua den cac may chit thoc con lit. BO can bang tai cling tang kha nang quan 15, bang each ttich (mg ding tit may chit. Vi do, chimg ta c6 tat ca !man may chit thoc sari sang lam viec, va cluing ta can chay hai ling citing: Web (HTTP), va FTP. Chimg ta chon chay FTP tren hai may chit va chay Web server tren tam may chit can Iii Uri vi nhu cau can Web server la nhieu han. Khong co b0 can bang tai, chimg ta se sir don DNS de thoc hien luau chuyen yang glib hai dja chi IP may chit cho FTP, va gifta tam dja chi may chit cho HTTP. Neu nhu cau cho FTP dot ngOt tang len, va chimg ta can chay no tren mot may chit nao d6 trong so cac may chit cluing ta c6, cluing ta phai sira dOi ngay 10 DNS vi them ba dja chi IP may chit. Cling viec nay mat mot khoang thai gian de co hieu qua thanh conp va se kh8ng the giai quyet duqc cac van de hieu suit ngay 1(tp hie. Neu cluing ta thay the ba, cach sir ding can bang tai, cluing ta chi can th6ng bao mot dja chi IP ao. Chimg ta co the cau hinh b0 ,can bang tai de lien ket dja chi IP ao yeti may chit 1 va2 danh cho FTP, va may chit? den 8 danh cho ling ding web. Dieu nay ducyc coi la mot so ring buk. Tit ca cac yeu cau FTP &roc nhon tren dong This is trial version www.adultpdf.com 17 Chuang 2: May chit can bang tai DS Van Thjnh - A13439 duqc biet den la 21. BO can bang tai nhon ra kieu you au nao dia tren ding dich TCP va huang no den may chit thich hqp. Neu nhu cau cho FTP tang len, clugg ta co the co may chit 3 choy img ding FTP, va buk may chit 3 dua IP lo &AA cho (mg ding FTP. 134 gib b0 can bang tai se nhon ra rang c6 ba may chit chay FTP, vi phan phoi cac you cau gifts ba may, do do ngay 14p tirc se tang tong ding suit danh cho cac you cau FTP. KM Wing di chuyen cac (mg ding tit mOt may chit nay den mot may chit khic hoc tang them nhieu may chit cho mOt img ding nhat djnh voi dieu kien khong mOt may chit nao bj gian don viOc dap img cac yeu can nia may Ichitch la mOt ding co molt me cho cac quan trj vien may chit. Can bang tai cung giap quan ly mot kh6i lugng Ion not dung dft yen. MOt so may chit Web co the co rat nhieu not dung de phvc vi nhtmg n6 lei khong the phi" hqp net chi hog dOng ten mOt may chi. Chigg ta co the t6 chirc cac may chit thigh cac nhOm khic nhau, trong do mai nh6m may chit se phai chin trach nhiem cho mOt phAn nhAt djnh cua not dung, va b0 can bang tai se djnh gran cac yeu du Whom may chi thich hqp dtra teen URL trong cac you cau HTTP. Can bang yin hog dOng dtra tren cac giao that mpg tieu chuin bon vOy no co the phan phoi tai den bit ky may chi nao ma khong can phiti phan biet he diet hanh cent may chit. Dieu nay cho phep cac quan tri vien co the pha trOn phi! hqp cac may chi khac nhau, va tan ding lgi the dm mil may chit de c6 dttqc ding suit tong hqp len nhat. An ninh: BIN vi b0 can bin tai ey phia truac nhom cac may chit nen b0 can bang tai co the bao vO de may chit ti" nhemg ngteti clang dOc h3i. Nhieu san pham can bang tai di kern veri mOt s6 tinh nanf bio mot ngan chart cac cuOc tan ding den cac may chit. Ck may chit thvc cung c6 the duqc cung cap dia chi IP private de chart bit 14 truy cOp rnrc tiep nao ta nguid dim& ben ngoai. Cac dia chi IP private khong the dinh tuyEn chung frog Internet, bit cir you cau noo trong mang Internet deu phii di qua mOt thiet bi thot hien dich dia chi mang de giao tiep Arai mOt may chit ce dia chi IP private. BO can bang nghiem nhien the trey thinh thiet bi trung gian dich dia chi mong nhtr mOt phan ph6i va chuyen tiep yeu au cita may khich den timng may chit thwc. Dia chi IP lo ten can bang tai c6 the la mOt dia chi IP public de ngtrei sir dung Internet co the troy cap IP lo. Tuy !glen, cac may chit thvc ding sau b0 can bang tai ce the co dia chi IP private de butjc tat ca cac thong tin lien lac phai thong qua cac can bang tai. Chat luting dick lc Chit luqng dich vi co the di:cc dinh nghia bang nhieu each khic nhau. NO c6 the &Km dinh nghia nhu la then gian dap img dm may chit hok (mg ding, hok la kha nang cung cap cac dich vi khac nhau dtra tren timg nhom nguoi ding. Vi do, d6i veri dich vv cim mOt website, n6 loon muon dap img mOt each nhanh nhat cac thong tin gin den cac thigh vien platinum, sau de mai den nhem cac thank vien gold va cac thanh vien silver. Lac nay can bang tai c6 the duqc sir ding de phan biet ngutri sir ding Oa tren mOt s6 th8ng tin trong cac geli tin yeu au, va din chting den mOt may chit hok mOt nhom cac may chi, hok thiet lop cac bit tru tien trong cac &Si tin IP de cung cap cac dich vi mong muon. This is trial version www.adultpdf.com 18 Chuang 2: May cha can bang tai DO Van Thinh — A13439 2.4. Luling g6i tin co ban trong can bing tai DE hieu n3 dugc lutmg di chuyen cua cac gal tin trong can bang tai chang ra hay quay ter lai yeti viec thiet lap can bang tai nhtr trong hinh: Real Sentra Maud Font,. VIIP••123.122121.1 l oad Raton, Carats Ira 1014103 VIP to Real Sent Blythe to lit Abort YIP VIP Pat 123.122 121.1 30 113.122.121.1 n 123.122 121.1 32 Red Sena RS1 itsz RSI S2 1C lea SNIP Real Sara Pat so am 21 12 IR Ifinh 2.4. nhom may cIni vat be) can bang tell Co ba may chit RSI den RS3 vi co ba ung dung dirge tai dat tren the may chit li Web(HTTP), FTP, SMTP. Ba img dung nay doge phan phial thong qua ba may chit. Trong vi dv nay tat ca cac img dung deu sir dung giao thac TCP, va mOi ang dung kheri chay dugc biet den tren moi dm* khac nhau. Ling dung Web chay tren cong 80, FTP chay tren cong 21, SMTP chay tren cong 82. Be can bang tai sir dung ding dich trong cac giao thac TCP cua cac gei tin den de than ra tins dung mong muon cua cac may khach vi Iva chgn met may chti thich hgp cho moi yet& cau. Qua trinh xac dinh may chit del gin you du can phai zee dinh re qua hai phan sau. Dau nen, can bang tai phai xac dinh rang cac thiet lap may chu dang chay cac ang dung dirge yeu cau can phiti c6 tinh trang tot. Thu hai, be can bang tai sir dung mOt thuat toan phan phei tai hoc phucmg thirc de Iva chgn mOt may chit, dva vao the dieu kien tai tren cac may chit khic nhau. MOt vii vi dv caa cac phucmg thac thuat toan can bang tai bao OM thuat toan lufin chuyen yang (round robin), ket not it that (least connection), phan phoi trong s8 (weight distribution) hoac dva tren thei gian dap ang de Iva chgn cac may chit. Cac phucmg lilac phan phoi tai se dugc than lujn chi riot ham trong cac phan sau. Qua trinh cau hinh hi) can bang tai cho vi dv nay lien quan den cac butt sau: 1. Dinh nghia mOt dia chi ip ao cho b0 can bang tat: 'VLP = 123.122.121.1 2. Xac dinh cac ang dung can can bang tai: Web, FTP vi SMTP This is trial version www.adultpdf.com 19 Chucmg 2: May chii can bang tai 131) Van Thinh — A13439 3. D6i voi moi ling dung, ring buOc dia chi IP ao cho moi may Si thuc dang chay ling dung do. Ring buOc dia chi VW den RS1 va RS2 cho ling dung Web, RS1 cho FTP, vi RS2 va RS3 cho SMTP. Dieu nay c6 nghia cong 80 cho VIP duqc ring buOc den cong 80 cho RS1 vi RS2, cling 21 cho VIP duqc ring buOc den cong 21 ten RS1, :. 4. Cau hinh de di the kiem tra duqc tinh tang ciia moi may chi\ b0 can bang tai can phai dimg de xac dinh dieu kien sac khae coa moi mOt may cha va ling dung. 5. Cau hinh phuong thirc phan ph6i tai cai dugc sir dung de phan chia Bing viec phan pheoi cac ling dung qua ba may chii va ring buOc VIP den cac may chi] thvc cho cac cong TCP khic nhau. Chimg ta da tach ling dung tit may chti de tit d6 cii thien han tinh Iinh hoot. Vi du, neu ling dung FTP c6 nhu cau sir dung cao, rat don gian chong ta c6 the them mOt may chi, nao d6 chity FTP bang each ring buOc them may chit den VIP tren cling 21. Neu RS2 co nhu cau can duqc bao tri,chCmg ta co the sg dung b0 can bang tai khdo leo thgc hien buck b6 qua RS2. CO nghia la no se gift lai cac yeu cau moi den RS2 va cher dqi mot khoing tiled gian nhit dinh cho den khi cac ket not hien c6 bi dgng lai. Can phai km y rang that cac cac may chi, thvc phai dirgc chi dinh mOt dia chi IP private nhu 14 10.x.x.x, 172.16.x.x — 172.31.x.x, 192.168.x.x cho hai muc dich chinh. Thu ngt, chimg ta bao ton khong gian dia chi IP public bang each chi sir dung mOt dia chi IP public cho dia chi VIP dai dien cho tom 1)0 he thong may chi' : Thu hai la Ling cueing an ninh khi kh8ng c6 mOt ai ngoai Internet cif) the truy cap trirc tiep tai cac may chi) ma khong phai th8ng qua by can bang tai. Bay WO chting ta hay cling xem nhemg gi 1)0 can bang tai thgc hien vi kiem tra luu lugng g6i tin Mau khi sir dung can bang tai. Sir dung mOt eau hinh don gian vai by can bang tai duqc dat truck 2 may cha Web nhu trong hinh ben duai, de c6 the hieu !thing gai tin trong moi phien you cau hoac tra lai. May may khach dau tien se thiet lap mOt ket not TCP, gai rmOt you cau HTTP, nhan duqc mOt phan ling , va dang ket not TCP. Qua trinh duet ket not TCP la mOt cai bat tay ba chieu. Khi by can bang tai than yeu eau TCP SYN, neo chira cac thong tin sau day: 1. Dia chi ngvein (Source IP address). Bieu thi dia chi IP ciia may khfich. 2. C8ng nguon (Source port). Qin duqc sir dung bai may khach trong ket not TCP. 3. Dia chi IP dich (Destination IP address). Day la dia chi IP ao dai dien cho cum may chfi chay ling dung Web. 4. ding dich (Destination port) Day la deg 80, theo tieu chuk Wirth cho may chii Web , la citing y8u eau cua mOt ling dung Web. This is trial version www.adultpdf.com 20 DO Van Thinh — A13439 Chuang 2: May chit can bang tai Client es 11111.1.1.100 100.1.1.100 141.149 65.3 2 ILI 1 1.100 10.10 1020 M2 Mr 3 10.101020 108.1.1.100 3411 M2 141.149.65.3 100.1.1.100 M2 MI Deg IP .. 0 111.149.65.1 MAC-MI lest MAC Nt2 Source MAC MI Source IP VIP - 141.119.65.3 MAC al RS1 10. 0.10.10 MAC -M3 RS2 10 10.10.20 MAC -M1 Hinh 2.5: luang g6i tin trong can bang tai Khi nhan duce gill tin TCP SYN, b0 can bang tai se chon may chit de chuyen tiep you cAu, vi do chqn may chit RS2 de gin xeu cAu. De cho may chit RS2 chip nhon can ea tin TCP SYN thi goi tin phai duqc giri den n6. Dia ‘ chi IP dich g6i tin phai c6 dja chi IP da RS2 khong phai dia chi IP ao. Vi voy can bang tai thay d6i ilia chi IP ao bang dja chi IP dm RS2 va chuyen g6i tin di. Qua trinh djch dja chi IP duqc gqi la djch dja chi mpg. Khi nguiri dung go www.kok.com trinh duyet se too ra mot truy yin gin den DNS va biet duqc VIP nhu la chit chi IP phoc vo www.kok.com . Trinh duyet cita may khach giri mot goi tin TCP SYN de thiet lap mot ket net TCP. Khi b0 can bang tai nhin duqc g6i tin TCP SYN, dau tien ne se xac djnh g6i tin nhu lit mot img vien cho viec can bang tai bed vi g6i tin chira VIP nhu la mot dja chi IP dich. Do day la mot ket net mai, b0 can bang kh8ng tim duqc mot myc trong bang phien cua n6 can duqc xac dinh bin dia chi IP nguen, IP dich, cling ngu6'n, cling dich nhu da duqc guy djnh trong goi tin. Dtra teen cAu hinh can bang tai va viec kiem tra tinh trong. BO, can bang tai xac djnh hai may chit RS 1 va RS2 nhu la vien cho ket mai nay. Bang each sir dong mot phuang thirc phan ph8i tai da duqc quy djnh, bi) can bang tai se chqn ,m0t may chi thus, RS2, cho phien nay. MOt khi may chit dich duqc xac djnh, b0 can bang tai too ra mot moc phien min trong bang phien cua no. BO can bang tai thay d6i dia chi IP dich va dia chi MAC dich in &Si tin thanh dia chi IP va dja chi MAC cis RS2 sau d6 chuyen tiep goi tin den RS2. Khi RS2 tra lai (von TCP SYN ACK,) bay gib goi tin den b0 can bang tai vin dja chi IP ngu'on da RS2 va dja chi IP dich cita may khach. BO can bang tai Hum hien viec thay the This is trial version www.adultpdf.com 21