array本地负载均衡详细技术介绍

2020/3/19TMXTechnicalTrainingServerLoadBalancing2020/3/192ObjectivesTounderstandServerLoadBalancingconcepts.TounderstandArrayServerLoadBalancingconfigurationsteps.2020/3/193TopicsUnit1:BasicServerLoadBalancingConceptsandConfigurationUnit2:AdditionalServerLoadBalancingConceptsandConfigurationAppendix:WebConcepts2020/3/194Unit1:BasicSLBConceptsWhatisServerLoadBalancing?SLBTerminologyArraySLBBenefitsSLBModesRealServicesSimpleGroupMethodsVirtualServicesSimplePolicyTypes2020/3/195WhatisLoadBalancing?It’sineverywhereactually!!!EmergencyClinicExpertClinicSLB:PolicySLB:Method2020/3/196WhatisServerLoadBalancing(SLB)?SLBallowswebsitestobescaledfromasingleservicetoagroupofservices(servicefarm)whiledistributingtheloadbetweentheservicesbasedontheirloadandhealth.SLBBenefitsGreaterscalabilityinthenumberofservicesforasitereducesloadonindividualservicesandimprovesresponsetimetoclientsImprovedresiliencythroughHealthCheckingofservices,services,andwebcontentBettercontrolofserviceresourceusagethroughimplementationofdifferentloadbalancingalgorithmsTrafficmanagementbasedonTCP/UDPportnumber,URL,HTTPHostHeader,Cookiecontent,orSSLSessionID2020/3/197SLBTerminologyRealService(“Real”)RepresentsaphysicalservicewhichwillhandleclientrequestsRealServiceGroup(“Group”)RepresentsagroupofrealserviceswhichtrafficwillbedistributedtoDefineswhichloadbalancingalgorithmtouseVirtualService(“Virtual”)RepresentsavirtualservicethatclientscanconnecttoPolicyAssociatesrealservicegroupswithvirtualservicesservice1service5service4service3service2Real1Real3Real4Real5Real2Group1Group2Virtual1Virtual2Internet2020/3/198ServerLoadBalancingExampleBasicServerLoadbalancingInternetServiceGroupRealservicesVirtualIP100.10.10.1012345Userenters(VIP)of10.10.10.10.2ClientsendsrequesttoVIP.3Arrayproxiesrequesttoselectedrealservice.4Furtherrequestsfromtheclientmaybesenttothesameoradifferentrealservice,dependingonpersistencyconfiguration.5DNS2020/3/199SLBModesServerLoadBalancingcanbeperformedintwomodes:ReverseProxyMode•ArrayTMproxiesallclientconnectionstorealservices.TransparentMode•ArrayTMtransparentlyproxiesallclientconnectionstorealservices.2020/3/1910ReverseProxyModePacketFlow1.ClientconnectstoVIPonArrayTMandsendsrequesttoArrayTM.2.ArrayTMopensanewconnectiontorealserviceandsendsrequesttoservice.3.servicerespondstoArrayTM.4.ArrayTMrespondstoClient.VirtualInternetservice1service2InsideInterfaceOutsideInterface12342020/3/1911ReverseProxyModeTranslationsVirtualInternetservice1service2InsideInterfaceOutsideInterface1234StepSourceIPSourcePortDestinationIPDestinationPort1Client-IPClient-PortVirtual-IPVirtual-Port2Inside-IPInside-PortReal-IPReal-Port3Real-IPReal-PortInside-IPInside-Port4Virtual-IPVirtual-PortClient-IPClient-Port2020/3/1912ReverseProxyModeBenefitsOne-armedtopologyispossible.•ResponsesautomaticallyreturntotheArrayTM.Enablesconnectionpoolingforincreasedperformance.Limitationsservicelogsdonotshowrealclient’sIPaddress(connectionsproxied).•Solution:EnablingX-Forwarded-Forheaderinsertionallowsclient’soriginalsourceIPaddresstobeinsertedintoHTTPrequestsbeforesendingtobackendrealservice.2020/3/1913ConnectionPoolingProvidesTCPaccelerationforbackendconnectionstorealservices.Arrayopensconnection(s)tobackendserviceasneededandleavesit(them)open.Arraysendsmultiplerequestsfromdifferentclientsthroughthesamebackendserviceconnection(s).Thissignificantlyreducesthenumberofclientconnectionsaservicehastohandle(typicallybyupto90%withcacheoff).Improvesserviceperformance.servicedoesn’tspendasmuchtimeperformingTCPsetups/teardowns.servicedoesn’tneedtokeepsomanyconnectionsopen.OnlypossiblewithReverseProxyMode.2020/3/1914TransparentModePacketFlow1.ClientsendsrequesttoVIPonArrayTM.2.ArrayTMforwardsrequesttorealservice,maintainingtheclient’sIP.3.RealservicereturnsresponseviaclientIP(handledbyArrayTM).4.ArrayTMforwardsresponsetoClient.VirtualIPInternetservice1service22354612020/3/1915TransparentModeTranslationsVirtualIPInternetservice1service2235461StepSourceIPSourcePortDestinationIPDestinationPort1Client-IPClient-PortVirtual-IPVirtual-Port23Client-IPClient-PortReal-IPReal-Port4Real-IPReal-PortClient-IPClient-Port56Virtual-IPVirtual-PortClient-IPClient-Port2020/3/1916TransparentModeBenefitsservicelogswillshowactualclientIPaddress.LimitationsRealserviceresponsesmustberoutedthroughtheArrayTMX.•EnsuresthattheArrayTMXcanseetheresponses.•One-armedtopologyisnotalwayspossible.Cannotuseconnectionpoolingfeature.•ArrayTMXcannotreusethesameserviceconnectionformultipleclientssinceeachclient’sIPaddressisdifferent.•Reverseproxymodeispreferredforperformancebenefits.2020/3/1917SLBRealServicesThefollowingparametersareassociatedwitharealservice:Realserviceprotocol(udp,tcp,ftp,http;tcpsandhttpsforSSL)RealservicenameRealserviceIPaddressRealserviceportHealthcheckmethodHealthcheckupHealthcheckdown2020/3/1918SLBGroupMethodsAgroupallowsrequests