Tìm hiểu hệ thống máy chủ cân bằng tải.PDF

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

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 stir 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

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

Tat

van de duqc sin chila Khi no da dugc sin xong, no phai dua ter lai de phuc vu Tat ca nhftng nhiem vu do inh huerng tai tinh skin sang va hieu qua dm CEng dung d6 deli v6i ngtreri &mg

Thech thzec 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

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

Chuang 1: Gieri thi0 DO Van Minh — A13439

Layer 7 Layer 6 Layer S Layer 4 Lam 3 Layer 2 Layer

Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Physical Layer

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

IITIR F17 SNMP

Telnet DNS TCP UDP

IP

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

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

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

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:

Tang khd ndng ddp itng nto 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

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 chit it

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

222.255.31.160

www.kok.com

Luan chuyon Ana DNS 222.255.31.161

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:

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

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

- Khong dit vi a 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

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

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,

Rtal %PMI'S

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

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

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 bat kY yeu cau 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

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

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:

Ira 1014103 SNIP

VIP to Real Sent Blythe to lit Abort

YIP VIP Pat Red Sena Real Sara Pat

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

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

Chuang 2: May chit can bang tai

DO Van Thinh — A13439

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

10 0.10.10 10 10.10.20

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

Chucmg 2: May chit can bang tai DS Van Thjnh - A13439

dja chi IP dm RS2 thinh VIP va chuyen tiep gen tin den b0 dinh tuyen phan phut gni tin den may khach Tat ca cac gei tin yeu cau vi tri liti trong phien TCP nay se trai qua qua trinh tuong tor Cu8i cling khi ket not duqc chfun dirt hoac duce thiet lop lai, can bang tai

se x6a mac phien trong bang phien dm n6

Th8ng qua luting gni tin chting to hay cling tim hieu 6 nai nao va lam the nao ma dja chi

IP va dja chi MAC duqc thao tac Khi bo djnh tuyen &tan &tic gin tin tir may khach, goi tin c6 mOt dia chi IP dich la VIP vi dja chi MAC dich la MI 11 dia chi MAC dial* djnh tuyen Trong buoy thin nhat nhu da the hien trong bang luting gel tin trong hinh BO djnh tuyen chuyen tiep cac g6i tin cho b0 can bang tai bang ckh thay &di dja dia chi MAC dich M2 la dia chi MAC dm can bang tai Trong Mac hai, can bang tai chuyen tiep gel tin den RS2 bang ckh thay doi dja chi IP dich vi dja chi MAC dich dm RS2 Trong bit&

ba, RS2 tra lai lai cho may khich nen dja chi IP vi dja chi MAC nguon la cita RS2 vi IP dich la cita may khach Cac dja chi cong mat djnh (default gateway) cho RS1 va RS2

&Km thiet lOp tir dia chi IP cita b0 can bang taivi vay dia chi MAC dich trong buck nay la dja chi dm bo can bang tai Trong buac bon, can bang tai nhan duqc gni tin vi thay doi dja chi IP nguon thanh VIP, dia chi MAC ngulin la dja chi MAC cita chinh na BO can bang tai can phai xac dinh b0 dinh tuyen yen dja chi MAC dich II MI

2.5 Kiem tra tinh trang stir khoe

Thuc hien cac cuOc kiem tra de xac dinh tinh trang sire Moe cita cac may chit vi cac *Jig dung la men trong nhfng lqi ich quan tang nhat cita can bang tai Khong ca b0 can bang tai, may khach co the se girl gni tin you du den mOt may chit dA chet va luc nay ngubi quan tri phai can thiep de thay the may chit da chat bang mitt may chit men hoac phai khic phuc duqc stir co Han nfta cac dung duqc cal int tren mOt may chit c6 the gap phiti mot so van de lien quan den lin pha'n mem Bei vay khi b0 can bang di duce trien khai de c6arthe phut hien cac van de nay va ngay lap tire hung may khach den mOt may chit thay the ma khong can den six can thiep huang dun sir dung tir ngueri quail tri

di mire dO cao ham, viec iciEm tra trinh trang sat khoe dm-tic chia thanh hai loci: kiem tra trong vanh dai va kiem tra ben ngoili vanh dai Vai cuOc kiem tra trong vinh dai, 130 can bang tai sir dung luting lint luting to nhien glum may may khach va may chit de xem xet neu mot may chit khOe manh Vi du neu bp can bang tai chuyen tiep gei tin SYN ciut may khach den may chit thuc, nhung !thong thity gni tin SYN ACK phin img lai tir may chit, b0 can bang tai c6 the nghi net c6 van de gi d6 din yeti may chit Lac nay b0 can bang tai

se kick hoot mOt cuOc kiem tra den cac may chit thuc va xac thuc lai ket qua kiem tra de Kiem tra ben ngoli vii dai 11 qua trinh kiem tra duqc tien hank bit nguan tir b0 can bang

2.5.1 Cic qui trinh kiem tra co bin

Chucmg 2: May chit can bang tai DO Van Thjnh — A13439

BO can bang tai co the thvc hien cac cuOc kiem tra khac nhau 0 mire thip nhat, b0 can bang di thin hien mOt s6 cuOc kiem tra o cac tang khac nhau trong mo hinh OSI

Qua trinh kiem tra 6 tang 2 trong m8 hinh OSI lien quan den met s6 giao thfrc phin gill dja chi (ARP), yeu cau duqc sir dung de tim dja chi MAC ttrcmg tang vai (Id chi IP Khi

130 can bang tai duqc eau hinh c6 thong tin dia chi IP cim may chit thvc, no girt ARP ten mai (Id chi IP cim may chit thvc de tim dia chi MAC Ck may chn se phai tra lbi loi cac yeu cau ARP trir khi n6 gap phai van de

Qua trinh kiem tra 6 tang 3 lien quan den viec ping dia chi IP ctia may ,chit thvc Ping 11 mOt chuong trinh duqc sir dung pile, bien nhat hien nay de hem tra stir ton di cim mOt dja chi IP trong mong

6 tang 4, b0 can biing tai co gang ket not tai mOt cling cu the TCP hoac UDP not ma cac img dung dang hoot dOng Vi du, Net' VIP biang bu(ic v6i cac may chit that tat-el don&

80 danh cho img dung Web, b0 can bang tai co8 gang thiet mOt ket, not hoc Co gang de gan vao cong dd BO can bang tai girl mot yeu eau TCP SYN den c ling 80 ten mai may chit thuc vi kiem tra bang each xem gai tin TCP SYN ACK co quay tr6 loi khan* Neu goi tin kh8ng quay tr6 loi, co nghia la viec tra 101 yeu cau that boi, n6 se danh dau cling 80 tren may chit ko c6 yeu cau tra lot Dieu quan tong can luu 5 , la b0 can bang tai xir ly min cling tren tong may chit 11 dOc lap Do da cling 80 ten tren mOt may cha nio da c6 the gap van de nhung ding 21 co the van duqc sir dung tot Trong twang hqp do, WO can bang tai ti6p tut xir dung may chn nay cho cac img dung FTP nhung se &nit dau tat a cac may chit khong sir dung duqc img dung Web Dieu nay cung cap can bang tai rat hieu qua, sir dung tai da nang lye ctia timg may chit

2.5.2 Cic cuOc kiem tra tren cac lug dyng cy the

BO can bang tai c6 the thvc hien cac cuOc kiem tra tang 7 trong m8 hinh OSI vi tren cac img dung Khong co qui de trong vipec lam the nao de mer rung viec kiem tra cac img dung nhung n6 kh6ng khac nhau la may khi kiem tra tren cac sari phim can bang di

Doi vai cac may chit Web, bij can bang tai c6 the girl mOt yeu cau HTTP GET hoc HTTP HEAD den may chit Chang to c6 the cau hinh b0 can bang de kiem tra cac dour[

ma HTTP quay tit loi ?hang hurt nhu "404 Object can not find" co the duqc pldt hien Doi WA DNS, 130 can bang tai c6 the girl mOt truy van DNS de giii quyet ten mien duac lua chqn tir ngtrai dimg thanh dja chi IP DOi voi FTP, b0 can bang cho the dang nh$p den mOt may chit FTP vesi mOt useriD vi mot khau cu the

2.53 Sy phy thui}c via on dung

Chuang 2: May cha can bang tai DO Van Thjnh — A13439

Doi khi chi:mg ta co the mu6n sir dung nhieu img dung co lien quan den nhau tren ding mOt may chti thuc Lay vi du, cac may cha Web cung cap cac img dung gi6 hang mua sam co img dung Web tren cong 80, de dam bao nOi dung vi cac in dung khac no sa dung them lap cong bao mat (SSL) tren cong 43, SSL cho phip cac may may khach vi may chi' Web trao doi nhang thong tin nhity cam nhu la thong tin the tin dung mOt each

an toan bang each ma has luu !IN:mg truy cop MOt Ichich hang dau tien se duyet trang web, dua them mOt vii muc =Jon mua vao trong gib hang ao vi nhan vao may cha thanh town Trinh duy'et sau da se chuyen doi sang img dung SSL, trong d6 co the thong tin dui the tin dung mua cac mat hang trong gio hang Die nay cac img dung SSL se lay ck thong tin gin hang tir cac img dung Web Neu img dung SSL gap phai van de, may chit Web can phai duqc xem xet lai Neu khong, ngutri dimg co the them cac muc mua sam vao gi6 hang, nhung se khong the truy cap cac img dung SSL de kiem tra Nhieu 1)0 can bang tai ho trq tinh nang gqi Whom cong, cho phep nhieu citing TCP hoac UDP duqc Whom

tai yeti nhau Neu mOt img dung chay tren bat kjr mOt cong trong ahem khong thanh b0 can bing tai se danh dau toan b0 nham cac *rig dung tren may chit thuc Dieu nay dam bao ring ngutri ding duqc djnh huOng den nhemg may chit c6 tat ca cac img dung can thiet de hoar' thanh mot giao dich

2.5.4 lqch Bin

MOt so b0 can bing tai cho phep ngutri dung c6 the via ra mOt kjch ban ap dung tat bo can bang tai, ne se chtia cac thong tin logic hoac nhemg chi dan kiem tra tinh trang sirc khoe aim may chit Tinh nang nay duqc sir dung pho bie'n trong cac thiet hi can bang tai

co chira mOt bien the dm mOt he dieu hinh tieu chain nhu Unix hay Linux ice tir khi cac

he dieu harth cung cap mOt so loci ngon ngit kjch bin, thong co the de dang khai thk de cung cap cho nguEri sir dung yeti kha nang via huOng din chi tiet cho cac img dung, may chi, hoac kiem tra nOi dung

MOt s6 nha quan tri may cha thich each tiep can nay bOi vi hq di biet cac ngon nger kjch ban, hq se tat dung sq linh hoot va sue math cum ca the kiem tra duqc cung cap bai kith ban

2.5.5 Ket Luin

Vi co fa nhiEu each khac nhau de kiem tra firth trang sire khae cila may chit cling nhu img dung, vay eau hei dat ra la mire dO kiem tra nao la thich hqp? That tuyet veri khi sir dung b0 can bAng tai, no dua tren cac tieu chart di kiem tra tinh trang sire khee ma khOng you

catu bAt IcSr ma doe quyen nao hoac bit kS, giao diet chuong trinh irng dung nao duqc tai

dat tren may chi Dieu nay dam bao ring thong ta ce the to do thay the mot san phim bo

can bang tai nay bing mOt sin phim b0 can bang tai Ichic, trong truang hqp 46 la mOt y'et cau Mat khac, muc dich chinh etia hi) can bang tai vin la kha nang phan phoi tai, neu n6 danh qua nhieu thin gian cho viec kiem tra tinh tang sue kh6e, thi se phai can thbi gian di

Chuang 2: May cha can bang tai 1)6 Van Thjnh — A13439

xir 15/ cac g6i tin you au, va ‘vin de nay !cluing phai la muc dich chinh chung ta mong muon That tuyet khi b0 can bang tai c6 the ket help va sir dung cac phtremg phap di duqc

de cap tren de tien hanh cac cuOc kiem tra mot each hieu qua nhat, vi quan trong la viec sir dung duqc toi da ngutm lye dim bao nhiem vv phan phoi tai

2.6 Djch dja chi ming (NAT)

Djch dja chi mpg la cac kh8i xay dung co bin trong can bang tai BO can bang tai ca ban sir dung NAT de you cau true tiep den cac may chit thvc khac nhau CO rat nhieu kieu NAT khac nhau ice tir khi b0 can bAni tai thay 461 dja chi IP dich tir VIP den dja chi IP cita mot may chi' thyc, ne duqc blest den nhtr la NAT dich Khi may chit thvc tra 18i, b0 can bang tai bay gib phai thay 6i dia chi IP cim may chit thvc trey Ivi thanh dja chi VIP Qua trinh dich dia chi IP xay ra tren IP nguon eim gin tin, trong khi d6 cau tra kri c6 nguon goc tir may chu den may khich

C6 ba thong s6 ma chimg ta can dac blest chu y de hieu ve NAT trong can bang tai d6 la: dja chi MAC, dia chi IP, va so cimg TCP / UDP

2.6.1 NAT dich

Qua trinh thay 461 dja chi dich trong cac g6i tin duqc gqi la NAT dich Hitt het cac b0 can bang tai thyc hien NAT dich theo each mac dinh Hirsh 2.5 da cho chimg ta thay each NAT dich lam viec nhu la mot phan ciut can bang tai Mai g6i tin deu c6 mot dia chi nguon va dja chi dich Khi NAT dich chi thvc hien thay dai veri dja chi dich del khi na

duqc gqi nhu la mot nira cim qua trinh NAT

2.6.2 NAT ngutal

Neu b0 can bang tai thay 461 dia chi IP nguon trong cac g6i tin cimg yen quit trinh dich dia chi IP dich, n6 duqc ‘gqi hi NAT nguen Dieu nay d8i khi cling duqc coi nhu la town b0 qua trinh NAT, vi dieu nay lien quan den den viec dich ca dia chi nguon va dia chi dich NAT ngutm thutmg khong duqc sir clung trir khi ce mgt cau true lien ket mpg cu the can del hbi phai c6 NAT nguon Neu cac m8 hinh mpg the hien viec cac g6i tin tra Ibi tir may chti thvc c6 the vtrqt qua No' can bang tai, NAT ngutin phai &Km thvc hien Minh 2.6 cho melt vi du ye cal nhin cap cao mot eau true lien ket mpg Hinh 2.7 cho thay mot thiet

ke mpg dam gian Tuning ,d6i heti phai sir dyng NAT nguon Dana each sir dtmg NAT nguon trong nhfmg thiet ke nay, chin ta da buOc may chit phan ph8i tra 161 thong qua 1,45 can bang tai

C.) Client requests

to VIP

Load Balancer

0 Load balancer

to real servers

.01=1•111=1•

0 Real server replies to client bypass the load balancer

Client

1711111

•

Hinh 2.6: Off nhin cap cao ve mot du true lien kit 'ming

replies to client bypass the load balance

Load

Load balancer

to real servers

Hinh 2.7 Mang don gidn nhung dot hid phiti sit dung NAT nguan

Khi duqc cAu hinh de thuc hien NAT ngu6n, by can bang tai se thay d6i dja chi IP ngtnin

trong tit ca cac gOi tin thanh mOt dja chi IP duoc cac djnh tren b0 can bing tai, dtroc goi nhu la IP nguern, trtrerc khi chuyen tiep cac gei tin den may chit thuc nhu trong hinh 2.8 Dia chi IP ngu6n nay co the gi6ng veri dja chi VIP hoac la khac nhau tity thuOc vao sin

Chuang 2: May chit can bin tai D8 Van Thjnh — A13439

phim can bang tai dang sit dung Khi may chit Uwe nhOn dtrqc cac goi tin, ne Ichong biet chinh xac may may khach nao da yeu cau b?ri vi got tin da dtryc giri thong qua be, can bang tai Cac may chit thut se tra Iai lai 130 can bang tai sau d6 nhimg gi bay gig can phai lam la bq can bang tai se Bich dia chi IP dich thanh dia chi IP clia may khach

f0rm1-1111.1.MS

14E10 SS

MAC M1

Id lialwattr

Vir al 141 le GS.3

MAC -MZ Smarr Irs141.111 101

1010 1010 MAC-M3

HInh 2.8: Luting gal tin trong NAT ngucin

Tir quan diem thong qua b0 can bang tat, c6 hai phien hqp IS, a day: phien tir phia may may khach va phien tir phia may chit mOi Olen tir phia may khach c6 mqt phien tir phia may chit ttromg img Hinh 2.9 se chi cho thay lim the nao de lien ket cac ‘phien, tir phia may khach tir phia may chit Ikea cac phien tit phia may chit ce IP nguon thikt lop IP ngu8n, duce xic djnh tren b0 can bang tat 80 can bang tat sir dung mOt ding nguon khk nhau de cho mai phien phia may chit de lien ket n6 veri mOt phien phia may may khach Dieu nay c6 hai tac dung Thu nhat, set ILK:mg tqi da cac phien dims thtri dtrqc bq can bang tai ho trq vtri mOt IP nguOn 11 65.536 (64K), b6i vi d6 11 gia trj tot da cho mqt cOng TCP

De h8 trq nhieu phien dung that, can bang tai cho phdp ngutri dimg cau hinh nhieu (Ha chi

MI 1 110 2e11 141 latIS 3 21 HI 111.10 1 Nal 1010 10 Ill 21

111.1.1.111 2000 141.141153 a algal 10102 alma a

la•t.ia 2001 141.141.613 a 141.16.101 WC Mita ZI

Hinh 2.9: Lien ket phien phia khcich hang va phia may chit khi sit dung NAT nguiin

Chuang 2: May che can bang tai DO Van Thjnh — A13439

Un diem cita NAT ngulin la n6 cho phdp ban hien khai be can bang tai 6 bet cu dau ma khong giei hart bat ky met cau tree lien ket mpg nito Diem bat Iqi la cac may chit thvc kung the thay dia chi IP dm may khitch ban dau, bei vi can bang tai da , thay dei dja chi

IP nguon M01 so img dung dva tren viec xac thvc IP ngu8n kungthe thvc hien duqc neu NAT ngu8n duqc sir dung MOt so nha quart tri Website cling thireng dva tren Whit ky may chit Web de xac djnh h8 so ngtrtri dimg dva tren dja chi IP nguon, va do do c6 the hp khong muon sir dung NAT nguOn Met so san phiun can bang tai co the giai guy& van de nay bang each cung, cap met so thy chon cho phdp dang nh'ap hoc bao cao dia chi IP nguon cac you cau gin den

2.63 NAT nglrot

Khi sir dung be can bang tai, cac may chit thvc thirtmg duqc gin dia chi IP private de tang artmg anh ninh bao msat va bito ton dia chi Be can bang tai thvc hien NAT dich cho tatca cac hru lupng truy , c#p duqc xtremg boi khach hang den ,cac may chit thvc Neu cac may chit thvc dang sau can bang tai muOn duqc ket non ra, ben ngoli, chung phai thong qua NAT bei vi may chi] thvc chi c6 IP private Be can bang tai c6 the duce can hinh de thvc hien qua trinh NAT nguqc lai non ma be can bang tai thay d6i dia chi IP elm cac may chikthvc thank dia chi IP public da dirpt xac dinh teen be can bang al Dia chi IP public co the giong nhu dia chi IP ao duqc xac dinh teen be can bang tai hoac la met dia chi IP rieng biet

2.6.4 NAT nfing cao (Enhanced NAT)

Nhang Icy thuot NAT vita trinh bay 6 tren deu xoay quanh viec thay dot dja chi IP, cling nhu dja chi cOng trong goi tin header Tuy &lien c6 'Mang giao thirc dac biet chira thong tin dja chi hay cOng tilning trong payload coa g6i geti tin, ding can phai duqc thay don cling yeti header gen tin

Dieu nay did hed be djnh tuyen phai hieu biet theo timg giao thirc cu the Khai niem NAT nang cao (enhanced NAT) nei den kieu NAT phirc tap dirge thvc hien voi tilifing lieu biet theo timg giao thirc cu the de lam cho Siang giao thirc de host d'Ong duqc von viec djnh tuyen goi tin

Trong só cac giao thirc dac biet do, thong dung nhat la the giao ,thirc plurong tin truyen thong (vi du RTSP) Day ding la cac giao thirc sir dung can bang tai , ph6 bison that, vi chimg kit non tai nguyen mpg va tinh toan khi phai phvc vv d8ng th&i cho hang tram den hang ngin ngu&i sir dung

Cic giao lac truyen dicing thirtmg gem c6 hai ket nor, met ket not dieu Ithien xay dung tren TCP vi met ket not du lieu dva ten UDP De khtd dau, may khach lchtri tao met kenh dieu khien den met cong da biet tren may chi, May khach vi may chit se thoa thuon

Chucmg 2: May chit can bang tai DO Van Thjnh — A13439

cac di'Eu lchoan cho kenh dieu khien Su thoa thuan g6m co IP caa may chit va s6 eking

dm may ma may khach se gin du lieu den tren ket not dCr lieu

Neu cac may chit c6 dja chi IP private, be ,dInh tuyen se thuc hien NAT dich cho ket not dieu lchien Nhung dong, thin be djnh tuyen cling phai xem cac thong tin thoa thuan va thay dei mei thong tin ye dia chi IP hay cong ma may chit va may khach trao doi sao cho may khach se girl du wou den dia chi VIP public chit khong phai IP private cim may chit (nhang thong tin nay nam trong payload dm geti tin)

Han nun, cong dich duce chqn trong qua trinh thoa thuan 13i khong biEt truck duce nen phai xir 19 you cau ngay ca khi cong chua duqc lien ket den bit 1c9 may chit nao

Tuy nhien, nhieu doanh nghiep lai co nhftng chinh rich bao mot tren ttrimg lira lam cho nhftng ket not dft• lieu tren nen tang UDP c6 the khOng thanh cong Do do nhieu he thong truyen thong cho phen lung tren nen HTTP, nghia la town by thing du lieu se duqc girl di bing ket not duqc thiet lap bei giao tiep HTTP DiEu nay lam cho viec NAT ter nen nhg nhang hon

2.6.5 Djch dja chi cling (PAT)

Qua trinh djch cong thuting duqc Wet ten la viec djch s6 cong trong cac gen tin TCP/UDP, di cho so dm* co the duqc sir dtmg trong cac giao thirc ;chic Qua trinh djch dja chi cong tren be can bang tai, khi gin cong 80 tren VIP thanh cong 1000 tren may chi' thtrc.130 can bing tai da djch so cong va chuyEn tiep yeu eau den may chit thtrc Djch dja chi cong dem lai ba lqi ich: dim bao an ninh, kha nang ma fen ting dung, kha nang quan

19

Bing cach chay nhieu img dung tren cac ding private, no co thE dam bao an ninh tot hun cho cac may chit then bing cach dung cac cong thutmg duqc biet den Vi du, chang to c6 the chay cac may chit Web tren ding 4000, va gin cong 80 dm VIP tren be can bang tai thanh cong 4000 tren may chit thuc Cac may khkh se khong nhan ra bit Ic9 sir khk biet nao va trinh duyet web tiep tuc gut cac yeu clw den con; 80 dm VIP BO can bing tit djch s6 cong trong tat ca cac yeu caur den vi chuyin tiep den cong 4000 tren may chit thuc Bay gib, khong met ai co thE tan cong cac may chit truc tiep bang cach thong qua viec 1, 11m luqng nguy hie'm den cong 80, bed vi no da duqc den Mac divoy, tin tac

co the co ging de tim niang cong dang ma, diEu nay chi tao ra Wit chat kh6 khan hon

Gan (Ha chi IP private den cac may chit thtrc hoc thtrc hien kiem soat danh sach cac truy cap de tit chei tat ca cac ltru luqng truy cap den dia chi IP cita may chit thuc, diEu nay se buetc tat ca nortri ding phai thong qua bo' can bang tai de co the truy cap vao cac may chit dive BO can bang tai sau d6 co the ethqc thi chinh sach truy cap nhat dinh vi cling co the bao ve may chit ch8ng lai mgt so loci hinh tan cling

Chuang 2: May chit can bang tai DO Van Thjnh — A13439

Dich dja chi cong giiup cal thin kha nang me rung bang cach cho phep chay nhieu img dung tuong tfr ten nhieu cong Ben vi yeti cach mOt so img dung duqc thiet ke chimg ta co the ma rang hiOu suit ang dung bang each chay nhieu ban sao elm no Thy thuijc vao img dung, chay nhieu ban sao co the sir dung nhieu CPU hieu qua han De dua ra mOt vi du, chting ta c6 the chay Microsoft IIS (Internet Information Server — Microsoft phan mem may chit Web) tren nhieu cong Chin ta co the chay HS troll cong 80, 81, 82, va 83 tren min may chit thurc va can rang buoc cong 80 tren VIP cho mot cong chay HS BO can bang tai se phan ph6i luu Krung truy cap khong chi ten khip the may chit thue, ma can

ca cac cong tren mot may chit thirc

Dich dja chi ding cling co the cat thin kha nang quan ly trong cac tinh huang nhat dinh

Vi du, khi chitng ta luu tit cac trang web tren mOt tap the may chit that, chimg ta co the sir dung dja chi VIP de dai din cho tat ca cac website BO can bang tai nhan dirge tat a cac yeu eau web ten cong 80 cho cong mgt dja chi VIP Chimg ta co the chay cac ang cbmg may chit Web ten mOt cong khic cho mot ten mien website Chit han, cac may chit Web http•//www.abc.com chay tren cong 80, va http://www.xvz.com chay tren cong 81

BO can bang co the duqc eau hinh giri cac luu lugng truy cap vao cong thich hqp, thy thuk vao ten mien trong URL cita mot yeu cau HTTP

2.7 Trir lai tir may cho film tiep (Direct Server Return - DSR)

DSR lien quan den, viOe chophdp may chit Ulm tiep tra km lugng tray cop ma khong th8ng qua b0 can bang tai Bang cach ;thong th8ng qua b0 can bang tai, thong ta co the co dirge hieu suet tot han neu b0 can bang tai la nth c8 ehai, bai vi bay gia ,b0 can bang tai chi phai xir19 cac luu lugrig you eau, cat giam doge so lugng the goi tin can phai xir 19

Qua trinh thiet lap de that hiOn DSR, b0 can bang tai se khong chuyen dia chi IP dich thanh IP cita may chit ma van gift nguyen la ilia chi VIP (IP public) BO can bang tai chi dOi dia chi MAC dich thinh dia chi MAC cita may chit de gai tin co the den dugc may chit Van de con 13i la lam sao de khi may chit nhan gal tin you eau tir 116 dinh tuyen chuyen den se khong tir ch6i, vi dja chi IP dich kh8ng phai la IP cita may chit, ma la dia chi VIP MOt each dim gian, ta cau hinh de dia chi VIP la dja chi cita loopback interface tren mot may chit BO dinh tuyen dung cach nay vi lqi dung nhUng tinh chat thti vi sau day cita loopback interface:

• Co the gin bat Ict dia chi IP nao, khong bit buOc phai bit dAu bang 127.x.x.x

• Vi loopback interface khong phai la mOt thiet bi that, no kh8ng co dia chi MAC, nen hg thong se khong tra lai cho cac yeu cau ARP Do 66 se khong co hg thiing ben ngoiti nit° ilia dirge dja chi IP cita loopback interface Tuy nhien, hg thong van nhan you cau den IP cita loopback interface va tra leti tutu la cac interface Ichic Nhu vay, bang mOt chit thin thuat vii cac dja chi, may chit thfrc khong an dja chi IP public van co the nhan you cau va tra Itri trip tiep cho may khach

Chuang 2: May ch6 can bang tai DO Van Thjnh — A13439

Hinh 2.10 the hien luting gal tin khi sir dung DSR Dim tien, b0 can bing titi gift nguyen dja chi IP dich van nhu la dja chi VIP trong gei tin yeu ceu, nhtmg thay doi dia chi MAC dich cua may chit da duqc chqn Itra BO chuyen mach lap 2 gifta bo can bang tai va may chit chuyen ti ep g6i tin den dung may chi' dua tren dia chi MAC dich May chit thuc se chap nhan gai tin bai vi dia chi IP dich caa goi tin vi dja chi VIP da duqc djnh nghia nhu

la dia chi IP loopback tren may chit Khi may chit tra 16i, dia chi VIP bay gibt trot thkh dja chi IP nguon, va dja chi IP dm may khkh tra thank Elia , chi IP dich ,Goi tin duqc chuyen tiep thong qua b0 chuyen mach lap 2 den b0 djnh tuyen, vi sau do den may khach ma Ichong can phai sir dung NAT

Chen • HS 1.1 100

41.14E65

MAC -MI

141 141148.3 MAC-M2

Same 111' Dna 111 Sown MAC One

10.10 1• 28

MAC

Hinh 2.10: Luting goi tin khi s& dung DSR

DSR rat hftu ich cho nhftng img dung ton bang thong nhu FTP, phtrcmg tien truy'en thong, Ida ma kich thuac cac ged tin tra led la rat Ian so yen kich thuac cac gai tin you cau thuat nay cung duqc img dung cho nhftng &iao thirc dei h6i phirc tap khi thuc hien NAT hay khong duqc bp djnh tuyen h8 trq Chang han nhftng giao thirc phucmg , tien truyen thong nhu trong phan NAT nang cao (Enhanced NAT) da de cpp, thi ta co the dung DSR thay vi NAT Chang ta ding nen can nhAc sa dung DSR khi trien khai tren mo hinh mang, khi ma hru luting tra 1oi tir may chit kh6ng dam Ho IA se di dung dich

Chuang 3: Thu* toan can bing tai DO Van Thinh - A13439

CHIYONG 3: THWiT TOAN CAN BANG TAI

3.1 Ni e dung kluii quit

Be can bang tai sir dung thuot toan I9c phan tan hoan toan de anh xa cac may khach den

cac may chit trong nh6m Thuat toan nay cho phip cac may chit trong nh6m din ra cac quyet djnh can bang it met each dec lap va nhanh chong cho ,timg gei den NO duqc toi tru hoi de cung cap kha nail can bang tai mOt each thong ke doi yeti met soItrqng 16n cac yeu eau nho do vo so may khach tao ra Neu so may khach hoc cac ket not may khfich tao ra cac tai qua chenh tech nhau tren may chit, thuat toan can bang it se it hieu quit Tuy ninon, unit don gian va toe dO cua thuet thin cho phdp cung cap hieu nang rat cao

bao gom ca thong luqng cao va thei gian dip Ong ngiin trong met dai rOng cac img dung

may khich / may chit thong clang

Be can biing tai xi: ly cac you cau ctia may khach bang cach din dui:mg cho met if le phan tram da ch9n nhOng yeu cau men cho timg may chit trong nh6m Thuat toan !thong dap img nhftng thay doi ye tai tren mtii may chit (chling han nhtr tai CPU hay van de sir clang

be nh6) Tuy nhien, qua trinh anh xa se duce thay d6i Ida quan he thanh vien trong nh6m thay d6i vi ti le phial tram tai phan b6 se duqc tai can bang

Khi xem xdt met g6i den, tat ca cac may chit thvc hien clang thai viec anh thiing ke de xac djnh nhanh cheng may chit nio se xi) ly poi do Qua trinh anh xa sir dung mOt ham ngau nhien de tinh mirc tru tien dm may chit dva tren dja chi IP NIA cling den caa may khkh cimg cac thong tin trans thai khac de t6i tru hoa viec can bing di May chit tuong img se chuyen gal d6 tir the tang clued len tang TCP/IP con cac may chit khac se loai be goi nay Qua trinh anh xa kh6ng thay d8i trir phi quan he gifra cac may chit trong nhOm thay doi, de dam bao rang dia chi IP vi cOng den cna may khach cho trutc se luon duqc anti xa den cang met may chi) trong nhom Tuy nhien, may chit cu the trong thorn ma dja chi IP va cOng den dm may khich anh xa ten khong the duqc xac djnh tram do ham ngau nhien c6 tinh den quan thanh vien trong nh6m hien tai vi qua khir de toi thieu hoa kha nang anh xa lai

Nhin chung, chat Itrqng can bing duqc xac dinh met each thong ke bed s6 luqng may khach tat) ra you cau Nhu ket cau tang giarn ve so lucong may khach theo thong ke, sv deu don ye chat luqng cita thuat toan can bang tai se thay d6i nhe De host di-ging can bang it

co do chinh xac cao tren mil host trong nhom, met phan tai nguyen he th6ng se duqc sir dung de do va phan Ung Mr& nheng thay doi ciut dd Str tra gia ye hieu rang nay phai duqc can nhac so yeti lqi ich cua viec tot da holt khil rang sir dung cac it nguyen trong nhOm (ve ca ban li CPU va bit) Trong bit dr twang hqp nao, viec sir dung hqp ly

cac ngu6n tai nguyen may chit phai duqc duy tri de co the phvc vv cho cac tai may khach khk trong traimg hqp xay ra 16i

Chuang 3: Thuat toga' can bang tai DI" Van Thjnh — A13439

Khi mOt may chit meri tham gia vao nh6m, n6 se kith hoat qua trinh hOi tu va mot quan hg thanh vien mai trong nhOm se duqc tinh town Khi qua trinh hOi to holn thanh, mOt phin tai thieu may khkh see duqc anh xa tai host mai BO can bang tai do cac ket not TCP tren mai host vi sau khi ket not TCP hiEn tai cua chfing holm thank, ket not tiep theo tir cac may khkh bj inh huong se duqc xir 15r btri host mai Do d6, cac host nen duqc bo suns vio nh6m nhftn thtri diem tai tang qui manh nham ten thieu hod hiEn turyng ngat quang cac phien De trinh van de nay, trong thai phien phai duqc , quan bei 1mg dung may chit sao cho n6 co the duqc ten du true hay duce tra lai tir bat Icy mOt may chit nio trong nhom Vi du, trong thai phien co the duce day den may chit ca sec dft lieu va lint trong the cookies dm may khach

3.2 Gaol thieu mOt so thu#t twin can bAng tai

3.2.1 Thu#t twin Round Robin

Day gqi 11 thuat than Ink chuyen yang, cac may chit se duct xem ngang hang vi sap xep theo mOt yang quay Cic truy van dich vu se !An luqt duqc giri tai cac may chit theo this tir sap xep

Vi :

Cau hinh mOt cum Cluster bao wim 03 may chit: A, B, C

You cau djch vu this nhat se duqc giri den may chit A

You cau djch vµ this hat se duqc giri den may chit B

Yeu cau djch vµ this ba se duqc giri den may chit C

You eau djch vitt this to se 1a1 duqc girl cho may chit A

Nhu \ray b0 can bang tai se phan phai tai va giri you cau Ian WO den timg may chit thyt trong cum may chit S6 ltrong cac truy van den timg may chit la ngang bang nhau, dieu nay dam bao rang cac may chit deu phai host dOng vii mOt cong suit ttrcmg tu nhu nhau

3.2.2 Thu#t twin Weighted Round Robin

Ban chit gitmg nhu thuat tom Round Robin, My nhien chung ta co the eau hinh cho mOt hay nhieu may chit nao d6 thutmg xuyen duqc sir dung hen, hay not each khic chting ta

co the dieu chinh sao cho cac may chit ea Wing lye xir ly khac nhau Mai mOt may chit den duct gin mOt tong s6, d6 la mOt gia trj so nguyen cho biet ding suit xis ly Trqng so mac djnh la 1 Lay vi du, c6 ba may chi A, B va C &Km On tong so tucmg img Ian lusrt

la 4, 3, 2 MOt trinh tu lap ke hoach se duqc clurc hien trong mOt chu ky, va cac truy van you cau djch vu se Ian luqt duce giri den timg may chi theo trinh tu nhu sau ABCABCABA Nhu vay trong qua trinh thuc hiEn, mOt trinh tu da duqc tao ra Wan theo tong so tren mai may chit

Chuang 3: Thuat toan can bing tai DO Van Thjnh — A13439

Thuat toan Weighted Round Robin khong can phai tinh den cac you cau ket not cho mai mot may chi, va chi phi lap ke nnanh la nho hem so veri cac thuat town ke hoach dong,

no cfmg co the c6 nhieu may chi hcrn Tuy nhien no co the dan den mat can bang tai Ong giaa cac may chi neu cac you cau tai qua Ion Dieu d6 la co the bon hau het cac yeu cau deu duqc dinh hueng den mot may chi

Thuat than Round Robin la mot throng hqp dac Wet cua thuat Wan Weigth Round Robin, trong do tat ca cac trong so deu bang nhau Chi phi cia viec tao ra cac trinh t1r lop Ice hoach khi sirs di); cac twig s6 6 min may chi la khong clang Ict Ben vay khong nhit thiet chi sir dung thuat toan Round Robin

3.2.3 Thu@ ban Least Connection

Thuat toan Least Connection dua teen tinh toan s6 luqng ket n6i a thirc hien can bang tai cho may chi, no se lir dOng bra chqn may chi veri so lining ket not dang host dOng la nho nhat Co nghia la n6 se djnh huang cac yeu cau nhan &lux tit mang den cac may chi v6i

so luqng cac ket not duqc thiet lap la it nhat Day la mot trona nhung thuat toan lap ke hoach ,d6ng, ben vi ne can phai tinh toan so cac ket not truc tiep cho men may chit Khi

mot so may chi c6 cing mot hieu suat xir 19 tucmg to nhtr nhau, viec 1#p ke hnach vat

thuat toan Least Connection de Oki phoi tai nhieu yeu cau kha la "min" beri vi hau het cac yeu cau se khong ce co hoi de duqc djnh hyena den mot may chit nao khac

Nhin so qua, thuat toan Least Connection au% co the sir dung hi'eu qua ke ca khi co nhieu may chi co nang lye xir 15, khac nhau, bed vi may chit nhanh hon se c6 nhieu ket not hon Nhung thuc te, no khong the lam viec that tot nhu vay beri vi trang thai TIME_WAIT cia giao thirc TCP thuemg chi keo dai 2 phin, trona khi 2 phit nay mot may chi may co luu luqng truy cap 16n thu&ng len den hang nein ket nen Vi da may chi A manh gap d8i may chi B, may chi A dang xir 1S hang ngan yeu cau va Oa china lai o trang thai TIME_WAIT nhung lie nay may chi B cling dang chat vat de XII 1S, cho xong hang ngan nhang ket not cia no Chinh vi vay, sir dung thuat toan Least Connection khong the can bing tai tot gifta cac may chi co kha 'tang xir 1S , khk nhau

3.2.4 Thutit bin Weighted Least Connection

Thuat toan Weight Least Connection ban chit gieing thuat toan Least Connection, nhung ching to co the cau hinh uu tien cho mot may chit trong curn may chi host dOng bang cach gan trong so cho mOi may chi Nhitng may chi co gig tri tong so lem hon se nhan duqc ti le ket not 'Neu hon Ngu&i quart trj mang co the du hinh phan chia Mpg so cho min may chit vet cac ket not mpg se duqc ten ke hooch den min may chit ma 6 do ti 10 phan tram cia s6 cac ket not hien then 6 men may chi la ti da cho khi thiet 1#p gan tong

so

Chuang 4: Thiet ke mang WA be can bing tai D6 Van Thjnh — A13439

CHVONG 4: THIET Kt MANG VOI BO CAN BANG TAI

Trong chuang nay, chimg ta se tap trung vao viec then khai b0 can bang tai tren he thong mans, can nhic va lua chgn cac this& kE co lien quan Can xay dung met , thitt ke giai quyet duce tinh sari sang cao, kha nang ma rang, kha nang quan va van de an ninh cho toan b0 he th6ng, dung then co the dam bao ,chiu dugc cac van de phat sinh khac nhau trong timg thanh phan mang khac nhau, bao germ ca can bang tai

Truerc, khi chimg ta di sau vao mat cau trtic ket mang cu the, chimg ta can bao quat mOt so khai niem ca ban Bat dau veri cac van de cim b0 can bang tai dugc then khai nhu mOt bo chuyen mach lop 2 hoac mOt b0 dinh tuxen I6p 3, vi die!' nay di y nghia quan tang trong viec thiet ke mang Sau do chang ta bat dau veri mot so mau thiet ke don gian

ma kh8ng giai quyet duqc tinh siin sang cao Tiep theo chimg ta thao Juan lam the nao di bey can bang tai lam viectheo cap de cung cap tinh sin sang cao, fru& khi chuyen sang de

cap Ong rai cacthiet ke c6 tinh sari sang cao va dua ra nhthrtg can nhac lien quan Chuang nay se co gang cho that' ,str phat trien caa cac nuo hinh mang khac nhau trai ngugc veri viec chi trinh bay mOt thiet ke mo hinh mang cu the

4.1 BO can bang tai nhw lit mOt bQ chuyen mach so vtri mOt bO dinh tuyen

Cac boat dOng co ban cim mOt b0 chuyEn mach la nhon get tin tren moat cong veto, xac djnh cac giao din dau ra, gui cac g6i tin tren cong ra Lam the nao dE bo chuy En mach xac dinh duqc giao din ra cho mOt gel tin can phy thuOc vao tong loai chuyEn doi

Ethernet lap 2 chuyen d6i sir dung dia chi MAC c6 sin trong lop lien ket da lieu coa met g6i tin (16p 2 trong m8 hinh OSI) de xac dinh cac cong giao din dau ra cho mOt g6i tin MOt b0 chuyen mach 16p 3, ding dugc biet den nhu mOt bo djnh tuyen, sir dung thong tin lop mang (16p 3 dugc the hi'en trong mo hinh OSI) de xac dinh cac cong giao din dau ra

dm met g6i tin Khi sir dung giao thirc intemet, bo chuyen mach 16p 3 sir dung thong tin dia chi IP trong g6i tin de xac dinh cac giao din dau ra cac gal tin

May lchach va may chit thubng dugc ggi nhu la cac host, tra den b0 dinh tuyen qua mOt default gateway c6 dirt chi IP duce cung cep bed ngueri quart tri mang Khi Wit host can phai girt mOt g6i tin den mOt, dia chi IP ma kh8ng c6 trong cling mot dja chi mang con cim

ne, host se giri cac g6i tin den default gateway cim ne, default gateway dm be) dinh tuyen

se sir dung melt giao thirc dinh tuyen d'E' xac dinh nai girl g6i da lieu du tren cac thong tin dia chi IP

BO can bang tai hoat dOng o lop 4 hoac cao hcrn phu thuOc vim cac tinh nang ma chin ta sir dung, Nhu da de cap, khi be) can bang tai nhan dugc mOt gel tin, g6i tin co dja chi VIP nhu la dja IP va dia chi MAC dm can bang tai la dia chi MAC dich BO can bang tai se

Cliental, 166.1.1.100

0

141.149.65.1 MAC-MI

Chuang 4: Thiel k'e mang veri b0 can bimg tai DO Van Thinh — A13439

xem xet thong tin tai lop 4 vi b ben trong g6i tin de xac dinh loai chirc nang can bang tai can [him hien Bang each sir dung the thong tin trong cac g6i di lieu cling veri viec kiem tra tinh trang sire kh6e may chit va dieu kien tai may chit, b0 Gang bang , tai se xic dinh may dich cho you cAu BO can bang tai sfra &di cac throng can thiet trong goi tin, chang han ram dja chi IP dich va so ding TCP hoAc UDP MOt khi &Ai tin da duqc sin ded, b0 can bang tai ,an phai xic dinh giao din dAu ra vi chuyen tiep gel tin BO can bing tai co the chuyen tiep cac goi tin neu n6 la mOt Ns) chuyen mach holm mOt bo dinh tuyen tny thuOc vio no duqc cau hinh nhu the nao

Hinh 4.1 cho thay luu luqng goi tin va dia chi IP qua b0 can bang ma kitting thqc hien

dinh tuyen lop 3 Default gateway cho the may chi' va b0 can bing tai da dutyc thiet l'Ap den b0 dinh tuyen tren Cac may chu trong cling mot mang con, va do do c6 the giao tiep veri nhau thong qua viec can bang tai ma Ichong an phii lien quan den cac b0 dinh tuyen Dieu quan frog la phai chu y IuOng cac gel tin to Rn lai cho may khich tir may chil dia chi MAC dich den Ml, dia chi MAC dm bij dinh tuyen Tuy nhien ac may ch8 ce dia

chi IP public n6i chung thutmg kh8ng dirge mong muon bed vi chting ta khong the brio

ton doge kW:Mg gian dirt chi Vies sir dung IP public tren cac may chi thirc se kitting the ngan chan mOt ngutri nio d6 muon truy cop tut tiep vao cac may chit, trir khi co cac chinh sach kiem soat truy cAp thich hqp dirge thuc thi tren bo can bang tai hoAc tren b0 dinh tuyen Chung ta cling co the sir dung dirt chi IP private cho the may chit, nhung bAy gitr echang ta se co hai mang con khac nhau ket not ten cling mOt interface cia b0 dinhtuyen BO can bang tai veri dia chi VIP public la mOt mang con vi the may chi WA dia chi IP private li cac mang con ;chic nhau Ching ta can phai xac dinh hai dja chi IP tren b0 dinh tuyen ket not veri can bang tai: mOt Ii dirt chi IP trong mane con cia dia chi VIP

va cac dia chi khac trong mang con dm the may chi MOt s6 sin pham can bing tai c6 the cung cap cac tinh Ming nham tranh sir can thiet khi xac dinh dia chi W tren interface cia b0 dinh tuyen

Dealt gamey for servers is at

b Me IP address on Ire totem ewers — 141 140.65.1

RS1 141.14965.10 MAC-M3

RS2 141.140.65.11 MAC-164

Hinh 4.1: Bo can bang tai khong Mm nhiem vu clinh tuyin

14114966.1 MAC• MI

0

Chuang 4: Thiet ke mang veibt) can bang tai DO Van Thinh - A13439

Hinh 4.2 cho they luting g6i tin vi dja chi IP veri cAu hinh hrcmg to nhu trong hinh 4.1, nhung cac default gateway cho cac may chit duct thiet 1{ip den dja chi IP ten be can bang tai BO can bang tai hoat dOng nhu met be dinh tuyen chuyen tiep cac g6i tin met cach thich hop pia chi IP default gateway duqc thiet 1.#p 1# 10.10.10.1 nhu duqc djnh nghia btren cac cong giao dien be can bang tai ket not den cac may chit Bari vi default gateway tren dm may chit duqc thiet 1(ip den dia chi IP tren be can bang tai, cac g6i tin tra len dm may chit se c6 dja chi MAC dich M2 ctia be can bang tai nhu trong hinh 4.2

lots load bolsocers P 10.10 10.1

Hinh 4.2: Bo can bang tai hoot (long nhu bo djnh tuyin

Chat nang dinh tuyen hoac chuyen mach thuc sir rieng biet so veri town be cac chin nang

dm be can bing tai CA djnh tuyen vi chuyen mach deu xac djnh hop tiep theo vi giao dien dau ra dua ten dia chi IP vi dja chi MAC Neu cac may chit thin vi be can bang tai cling mang con hoc mien quang ba, be can bang tai c6 the thuc hien chuyen mach lerp 2

de giri cac g6i tin den cac may chit thuc, !feu be can biing tai yi cac may chit thut kh8ng

nam trong cling mien quartg ba, cac gal tin sau d6 duce chuyen tiep den may chit thuc se biphu thuec vio be can bang tai ceo chirc nang cue b0 chuyen mach dm 16p 2 hay 16p 3 Neu be can bang tai nhu met be chuyen mach 16p 2, be can bang tai se giri g6i tin den default gateway dm na vi g6i tin se duqc giri den may chit thuc Neu be can bang tai nhu

la met be chuyen mach lerp 3, net se cac djnh hop tiep theo dua tren bang djnh tuyen Ngoai ra neu be can bang tai hoat dOng nhu met be dinh tuyen 16p 3, se c6 met lqi ich rat quan tong, cac may chit c6 the 1r6 den be can bang tai nhu la met default gateway cue n6 Dieu nay dam bao rang cac luring g6i tin tra Ibi tir may chit se phai thong qua be can bang tai

IVIP•.141.149.65.3

MAC M2 Gateway IP-10.10.10.1

Load Balancer

Swat*

12

Chuang 4: Thiet ke mang yeti be can bang tai DI) Van Thinh — A13439

Trong phan con 13i cua chuang nay, chi mg ta se xem xet cac tin& ke trong do be can bang tai duqc sir dang nhu met be djnh tuyen, default gateway cho cac may chit co the duqc thiet 18p den ilia chi IP dm be can bang tai

4.2 Cie thiet ke Han gain

Bay gia chimg se de cop ve met s6 thiet Ice mpg don gian cho viec trien khai , m0t can bang tai ma khong giii quyet dtrqc tinh san sang cao Sau d6 chting ta se phat trien nhftng thiet ke co ban de giai quyet san sang cao

Thiel ke don

bang

nhu trong hinh 4.1 va 4,2, trong do cac may chtl &Km ket not mit tiep den 130 can bang tai Cac may chit thutmg duqc ket not den b0 can bang tai bang cach sir clang cac ket 100-Mbps va b0 can bang tai duqc ket not yeti the be djnh tuyen bang each sir clang lien ket 100-Mbps hok lien ket gigabit Chimg ta ding co the ket not tat ca cac may chit can bring tai yeti cac ket gigabit, va sir clang hai hoc nhieu lien ke't gigabit router Thiet ke nay giffri hart s6 lucing may chit WA so luqng cong c6 san tren b0 can bang tai Mot dO cong tren men san pham can bang tai 11 khk nhau, mot do cong va gia cho mot citing tren b0 can bang tai ding c6 the kh8ng eon nhu ctia N chuyen mach 16p

2 hay lop 3 VI vay, Ihieu khach hang trien khai mot be chuyen mach 16p 2 de ket not cac may chit, va be chuyen mach lap 2 Mn ltrqt ket not den be can bang tai thong qua lien ket 100-Mbps hok gigabit, nhu the hien trong hinh 4.3

Client-188.1.1.100

I C I

141.149.65.1 MAC=141

Hinh 4.3: Cac miry cirri drew kit nil thong qua bo chuyin mach lop 2