UDTUDPbasedDataTransfer.ppt

UDT:UDPbasedDataTransferYunhongGu&putingUniversityofIllinoisatChicago02/17/2004OutlineBackgroundUDTProtocolUDTCongestionControlImplementation/SimulationResultsSummary02/17/works:puting,accessofbulkscientificdata,datamining,highresolutionvideo,:EfficientandfairbandwidthunitizationTCPdoesnotwork!02/17/2004Trans-AtlanticTCPPerformanceChicago->Amsterdam,1Gbpslinkcapacity,110msRTTTCP:******@defaultsetting(64KBbuffer)TCP:******@12MBbuffer(=1Gbps*110ms)ParallelTCP:******@64TCPconcurrentflows,witheachhaving1MBbufferTwoconcurrentTCPflows,1fromChicagotoAmsterdam,works:!02/17/2004WhyTCPFailsDiscover/olinkerrorinhighBDPlinksB:throughoutinpacketspersecond,p:lossrate02/17/2004RequirementstotheNewProtocolFASTHighutilizationoftheabundantbandwidtheitherwithsingleormultiplexedconnectionsFAIRIntra-protocolfairness,patibility02/17/2004UseScenariosSmallnumberofsourcessharesabundantbandwidthBulkdatatransferMostofthepacketscanbepackedinmaximumsegmentsize(MSS)inaUDTsessionMSScanbesetupbyapplicationsandtheoptimalvalueisthepathMTU02/17/2004UDT:UDPbasedDataTransferReliable,applicationlevel,duplex,transportprotocol,overUDPwithcongestioncontrolImplementation:OpensourceC++libraryTwoorthogonalpartsTheUDTprotocolframeworkthatcanbeimplementedaboveUDP,withanysuitablecongestioncontrolalgorithmsTheUDTcongestioncontrolalgorithm,whichcanbeimplementedinanytransportprotocolssuchasTCPWhat’sUDT?02/17/2004PacketStructureDataPacket:Header:1bitflag+31bitsequencenumberControlPacket:Header:1bitflag+3bittype+12bitreserved+.+(0-32n)bitcontrolinfoType:ACK,ACK2,NAK,Handshake,Keep-alive,andShutdownActualsizeofaUDTpacketcanbeascertainedfromUDPheader02/17/2004DataPacket0PacketSequenceNumberUserDataPayloadFlagBit:0UDTuses31-bitpacketbasedsequencenumber,rangingfrom0and(231-1)Sequencenumbermaybewrappedifitexceedsthemaximumavailablenumber02/17/2004