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I. Khi nim load balancing.T dch st ngha nht ca t ting Anh load balancing ra ting Vit

l cn bng ti. Hn ai hc trong lnh vc cng ngh thng tin v snghe qua cm t ny, nhng th no l cn bng ti?!

Trong mng my tnh, cn bng ti l mt k thut phn phikhi lng cng vic ng u gia hai hoc nhiu my tnh, kt nimng, CPU, cng, hoc cc ngun lc khc, c c s dng ngunlc ti u, ti a ha thng lng, gim thiu thi gian p ng, v trnhtnh trng qu ti. S dng nhiu thnh phn vi cn bng ti, thay v mtthnh phn duy nht, c th lm tng kh nng lm vic. Cc dch v cnbng ti thng c cung cp bi mt chng trnh chuyn dng hocthit b phn cng (nh l mt chuyn mch a tng hoc mt my chDNS). N thng c s dng trung gian truyn thng ni b trongcc computer clusters ( cm my tnh ) , c bit l high-availability

clusters.C th load balancing ngn nga s qu ti ca cc server khi c qunhiu yu cu gi v bng cch phn phi v s nhng yu cu truy cpny mt cch hp l cho cc server khc nhau. Yu cu s c gi ncho server ang sn sng nht v mt hiu sut s dng. L trnh cc yucu cng c th xc nh da vo ni dung truy cp, chng hn nh lvideo hay vn bn. Bng cch nm r v tr cn n ca cc yu cu cngnh mc ti hin hnh ca cc server chng c th xc nh c nnchuyn yu cu tip theo ti u!

II. Cc tnh nng cn bng tiCn bng ti phn cng v phn mm c th n vi nhiu tnh nng cbit.-Asymmetric load (Khng i xng ti) : t l c th c phn cng theocch th cng gy ra mt s my ch ph tr c c mt phn lnca khi lng cng vic hn nhng ngi khc.-Priority activation (u tin kch hot) : Khi s lng cc my ch c sngim xung di mt s lng nht nh, hoc ti c qu cao, my ch dphng c th c a vo s dng ( online )- SSL offload v Acceleration: ng dng SSL c th l mt gnh nng lnv ti nguyn ca mt my ch web, c bit l vo CPU v ngi dng cuic th thy mt phn ng chm (hoc ti cc my ch rt t khi chi tiu nhiuchu k thc hin nhng iu h khng c d nh lm). gii quytnhng loi vn trn, Cn bng ti c kh nng x l SSL, gim ti trongphn cng chuyn dng ang s dng. Khi Load Balancers ang dng cckt ni SSL, gnh nng trn My ch Web ang gim v hiu sut s khnglm suy gim cho ngi dng cui.-Distributed Denial of Service (DDoS) bo v tn cng : cn bng ti c th

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cung cp cc tnh nng nh SYN cookie v tr hon-binding (pha sau mych kt thc khng thy client cho n khi n kt thc ca n kt hp TCP) gim thiu tn cng SYN Flood v ni chung offload lm vic t cc mych vi mt nn tng hiu qu hn.-HTTP compression (HTTP nn): lm gim s lng d liu c chuyn

giao cho cc i tng HTTP bng cch s dng nn gzip sn trong tt ccc trnh duyt web hin i- TCP offload: nh cung cp khc nhau s dng cc iu khon khc nhaucho iu ny, nhng tng l bnh thng mi yu cu ca HTTP t miclient l mt kt ni TCP khc nhau. HTTP/1.1 s dng tnh nng ny cng c nhiu HTTP theo yu cu t client nhiu vo mt cm TCP duynht cc my ch back-end.- TCP buffering (TCP m): s cn bng ti c th m hi p t my chv spoon-feed d liu ra chm client, cho php cc my ch chuyn sangcc nhim v khc.

-Direct Server Return: mt la chn phn phi ti khng i xng, trong c yu cu v tr li cc ng mng khc nhau.- Kim tra Health: cc cuc thm d my ch s cn bng cho Health lpng dng v g b cc my ch tht bi t h bi.-HTTP caching: vic cn bng ti c th lu tr ni dung tnh cho mt syu cu c th b x l m khng cn lin h vi cc my ch web.-Lc ni dung: mt s cn bng ti c th thay i ty tin giao thng trnng thng qua.-HTTP bo mt: mt s cn bng ti c th n cc trang li HTTP, g bcc phn u nhn dng my ch t hi p HTTP, v cookie m ha

ngi s dng cui cng khng th thao tc chng.-Priority queuing (u tin xp hng): cn c gi l t l hnh, kh nngu tin khc nhau giao thng khc nhau.- Content aware switching (Ni dung chuyn i nhn thc): hu ht cc cnbng ti c th gi yu cu n cc my ch khc nhau da trn URL cyu cu.- Client authentication (xc thc client ): ngi dng xc thc i vi nhiungun khc nhau xc thc trc khi cho php h truy cp vo mt trang web.- Programmatic traffic manipulation (Thao tc chng trnh giao thng): tnht mt cn bng ti cho php s dng mt ngn ng kch bn cho phpty chnh phng php cn bng ti, thao tc lu lng truy cp ty , vnhiu hn na.-Firewall ( tng la): kt ni trc tip ti my ch backend l phng nga,v l do an ninh mngPhng chng xm nhp h thng: cung cp ng dng lp bo mt, thm vomng / lp vn ti c cung cp bi tng la bo mt.

III. K thut cn bng ti mng(NLB: Network load balancing)

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Xem trong file .pdf rt r rng v c th.

IV. Cc link tham kho

http://my.opera.com/thanhdanh7604/blog/show.dml/4370552

http://nhatnghe.com/forum/showthread.php?t=40921

http://my.opera.com/thanhdanh7604/blog/show.dml/4370552http://nhatnghe.com/forum/showthread.php?t=40921http://my.opera.com/thanhdanh7604/blog/show.dml/4370552http://nhatnghe.com/forum/showthread.php?t=40921