Lecrouter1.ppt
- 文档编号:1380372
- 上传时间:2022-10-21
- 格式:PPT
- 页数:22
- 大小:131.50KB
Lecrouter1.ppt
《Lecrouter1.ppt》由会员分享,可在线阅读,更多相关《Lecrouter1.ppt(22页珍藏版)》请在冰豆网上搜索。
Spring2002,CS461,1,RouterConstruction,OutlineSwitchedFabricsIPRoutersTagSwitching,Spring2002,CS461,2,Workstation-Based,Aggregatebandwidth1/2oftheI/Obusbandwidthcapacitysharedamongallhostsconnectedtoswitchexample:
1Gbpsbuscansupport5x100Mbpsports(intheory),Packets-per-secondmustbeabletoswitchsmallpackets300,000packets-per-secondisachievablee.g.,64-bytepacketsimplies155Mbps,Spring2002,CS461,3,SwitchingHardware,DesignGoalsthroughput(dependsontrafficmodel)scalability(afunctionofn)Portscircuitmanagement(e.g.,mapVCIs,routedatagrams)buffering(inputand/oroutput)Fabricassimpleaspossiblesometimesdobuffering(internal),Spring2002,CS461,4,Buffering,Wherevercontentionispossibleinputport(contendforfabric)internal(contendforoutputport)outputport(contendforlink)Head-of-LineBlockinginputbuffering,Spring2002,CS461,5,CrossbarSwitches,Spring2002,CS461,6,KnockoutSwitch,ExamplecrossbarConcentratorselectlofnpacketsComplexity:
n2,1,2,3,4,Outputs,Inputs,Spring2002,CS461,7,KnockoutSwitch(cont),OutputBuffer,Spring2002,CS461,8,Self-RoutingFabrics,BanyanNetworkconstructedfromsimple2x2switchingelementsself-routingheaderattachedtoeachpacketelementsarrangedtoroutebasedonthisheadernocollisionsifinputpacketssortedintoascendingordercomplexity:
nlog2n,Spring2002,CS461,9,Self-RoutingFabrics(cont),BatcherNetworkswitchingelementssorttwonumberssomeelementssortintoascending(clear)someelementssortintodescending(shaded)elementsarrangedtoimplementmergesortcomplexity:
nlog22nCommonDesign:
Batcher-BanyanSwitch,Spring2002,CS461,10,High-SpeedIPRouter,Switch(possiblyATM)LineCardslinkinterface(input,output)routerlookup(input)commonIPpath(input)packetqueue(output)ControlProcessorroutingprotocol(s)exceptionalcases,Spring2002,CS461,11,IPForwardingisSlow,Problem:
classlessIPaddresses(CIDR)Routebyvariable-lengthForwardingEquivalenceClasses(FEC)FEC=IPaddressplusprefixof1-32bits;e.g.,172.200.0.0/16IPRouterforwardingtbl:
matchIPaddresstoFECw/longestprefix,Spring2002,CS461,12,Primarygoal:
fast,cheapforwarding1Gb/sIProuter:
$187,0005Gb/sATMswitch:
$41,000CreateVirtualCircuitatFlowSetupCellForwardingindex,swap,switch,ATMForwarding,Spring2002,CS461,13,Cisco:
TagSwitching,AddaVCI-liketagtopacketsTSRusesATMswitchhardwareIProutingprotocols(OSPF,RIP,BGP)buildforwardingtablefromroutingtableGoal:
IProuterfunctionalityatATMswitchspeeds/costs,Spring2002,CS461,14,Forwarding,ShimbeforeIPheaderTagForwardingInformationBase(TFIB)JustlikeATMindex,swap,switch,Spring2002,CS461,15,TagBinding,NewFECfromIProutingprotocolsSelectlocaltag(indexinTFIB)NeedfornexthopOtherroutersneedmySolution:
distributetagslikeotherroutinginfo,Spring2002,CS461,16,TagDistributionProtocol,SendTDPmessagestopeersUponreceivingTDPmessage,checkifsenderisnexthopforFECyes,savetaginTFIBno,candiscardorsaveforfutureuseControl-drivenlabelassignment,Spring2002,CS461,17,TheFirstTag,Twokindsofrouters:
edgevs.interiorEdge:
addshimbasedonIPlookup,stripatexitInterior:
forwardbytagonly,Spring2002,CS461,18,RobustnessIssues,Whatiftagfault?
trytoforward(defaultroute)discardpacketForwardingLoopstopologychangescausetemporaryloopsTTLfieldintag,sameasIP,Spring2002,CS461,19,Ipsilon:
IPSwitching,RunonATMswitchoverATMnetworkATMhardware+IPswitchingsoftwareIdea:
ExploittemporallocalityoftraffictocacheroutingdecisionsAssociatelabels(VCI)withflowsforwardpacketsasusualmaindifferenceisinhowlabelsarecreated,distributedtootherrouters,Spring2002,CS461,20,IPSwitch,AssumedefaultATMvirtualcircuitsbetweenroutersRouterrunsIProutingprotocol,canforwardIPpacketsondefaultVCsIdentifyflows,assignflow-specificVCflow=portpairorhostpairData-drivenlabelassignment,Spring2002,CS461,21,FlowSetuponIPSwitch,GetIFMP,ATMSwitch,Controller,Porti,Portj,vci=x,vci=y,Portc,vci=x,IFMPmessage,IFMPmessage,Spring2002,CS461,22,Comparison,SwitchbyflowDatadrivenSoft-statetimeoutBetweenend-hostsEveryroutercandoIPlookupScalable?
SwitchbyFECControldrivenRoutechangesBetweenedgeTSRsInteriorTSRsonlydotagswitching,IPSwitching,TagSwitching,
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- Lecrouter1