Chapter 02-1 - Introduction to Server Load balanci

2020/2/25APVTechnicalTrainingChapter02-1–IntroductiontoServerLoadBalancing2020/2/252ObjectivesTounderstandServerLoadBalancingconcepts.BasicNetworkTopologies2020/2/253TopicsUnit1:WebConceptsUnit2:BasicServerLoadBalancingConceptsandConfigurationUnit3:AdditionalServerLoadBalancingConceptsandConfiguration2020/2/254Unit1:WebConceptsTCP3-WayHandshakeHostNamesandDomainNamesHTTPandHTTPSHostNamesandDNSURLHAPVLWebPageObjectsCookies2020/2/255TCP3-WayHandshakeUnderstandinghowTCPnegotiatesaconnectionClientTCPSYN,Dport:80/Sport:xxxxWebserviceTCPSYN-ACK,Dport:xxxx/Sport:80TCPACK,Dport:80/Sport:xxxxDataFlowTCPFIN-ACK,Dport:80/Sport:xxxxTCPFIN,Sport:80/Dport:xxxxTCPACK,Sport:80/Dport:xxxxOpeningaTCPConnectionClosingaTCPConnection2020/2/256HTTPandHTTPSHTTP(HyperTextTransportProtocol)istheprotocolwhichallowsdatarequests(suchasHAPVLpages)andresponsestobetransmitted.HTTPistransportedoverthenetworkinTCP/IPpackets•Well-knownportisTCP/80,butcanrunonanyTCPportHTTP1.0andHTTP1.1differences•HTTP1.1allowsmultipleGETrequeststobesentonthesameTCPconnectiontoreducelatencycausedbyconnectionsetup/teardownforeachrequest(asinHTTP1.0).•HTTP1.1introducescachecontroloptionsintheHTTPheadersHTTPS(HTTPoverSSL)allowsHTTPcommunicationstobesecured(encryptionandauthentication).2020/2/257HTTP1.1PersistencePackettraceshowing:TCPhandshakeMultipleHTTP1.1GETrequestsoverthesameTCPconnection(clientsourceport1368)2020/2/258HTTPStatusCodesExamplesofCommonHTTPReturnCodes100(Continue)•Promptstheclienttocontinuesendingrestoftherequest.200(OK)•Therequestwassuccessfulandcontentwillbereturned.302(MovedTemporarily)•Therequestedresourcehasmoved,butfuturerequestsshouldcontinuetocometotheoriginalURI.SuppliesatemporaryURIforthatresource.304(NotModified)•Cachedcopiesoftheresourcearestillvalidforreuse.404(NotFound)•TheresourceindicatedbytheURIisnotavailableontheservice.503(ServiceUnavailable)•Theserviceistemporarilyunabletorespondtotherequest.•ReturnedbytheAPVwhenitcannotfindavalidbackendservice.2020/2/259HTTPHeadersHTTPHeadersDefinetherulesandprovideinformationaboutthedatarequest/responseClientHTTPHeaderexamples:•Cookie:name=value;•If-Modified-Since:Mon,17April200114:12:22GMT•Host:serviceHTTPHeaderexamples:•Set-Cookie:name=value;options•Last-Modified:Wed,21March200109:30:01GMT•Cache-Control:max-age=2314(inseconds)2020/2/2510HTTPTransactionExamplePackettraceshowingHTTPGETandResponseGETrequestHostHeader200OK2020/2/2511HostNameNamegiventoanapplicationserviceornetworkdevice.Anynamecanbeused,butmostInternetserviceshavestandardnamessuchasDomainNameNamegiventoidentifyanentityororganization.•Example:arraynetworks.netCommontop-leveldomains:.com,.org,.net,.co.jp,.or.jp,.ne.jpAFullyQualifiedDomainName(FQDN)consistsofahostnameanddomainnamecombinationwhichuniquelyidentifiesahostwithinanorganization.Format:host-name.domain-nameExample:(DNS)DNStranslatesanFQDNtoanIPaddressExample:DNSnamesusedtoaccessInternethostsMucheasiertorememberanamethananIPaddressArequestforatranslationiscalledaDNSquery.DNSRecordtypesA(Address)–AssociatehostnametoanIPaddress.MX(MailExchanger)–Referstomailservicesforthedomain.NS(Nameservice)–ReferstoDNSservicesforthedomain.PTR(Pointer)–AssociateIPaddresstoahostname.Etc…2020/2/2513URLURL(UniformResourceLocator)specifiesaprotocol,host,andresourceFormat:protocol://host/resourceExamples:•••HAPVL(HyperTextMarkupLanguage)isthe‘language’inwhichWebpagesarewritten.Example::•hAPVl•head•titleTestPage/title•/head•body•Thisisatest•/body•/hAPVl2020/2/2515WebPageObjectsWhatisonaWebpage?AWebpageiscomprisedofmany“objects”whicharefetchedbyseparateHTTPGETrequestsinthebackgroundTheArrayADCApplianceisanintegratedwebtrafficmanagementappliancethatacceleratesandstreamlinesthedeliveryofwebcontentforwebsiteswiththroughputreachingupto750Mbps.Designedfromthegrounduptointegratekeywebnetworkingfunctionsthatworktogetherseamlesslyforhighperformance,reliability,andscalabilityArrayNetworks’patent-pendingappliancesimplifiessiteoperations,reducingoreliminatingmanyoftheproblemsassociatedwithtraditionalmultiplevendordeployments.Staticimages(.jpg/.gif)ImageswithlinkstootherpagesTextProducts2020/2/2516CookiesAcookieisatextstringthatiscreatedbyawebserviceandsenttoawebbrowser.UsedasamethodformaintainingstateontheWebExample:•Storeusernameincookieonthefirstvisittoawebsite.Onthenextvisittothesamesite,youreceiveacustomwelcomepage.•Storeshoppingcartinformation.•servicepersistencysofuturerequestsgobacktosameservice.AcookieconsistsofaName=ValuecombinationExampleCookie:SID=service3CookietypesTemporarycookie:Deletedwhenwebbrowserisclosed.Permanentcookie:Notdele