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1、补充：网络与通信,08通信概预算补充定额,08通信定额补充定额,通信工程补充定额,网络通讯平台,网络通讯解决方案,网络通信工程师,通信补充定额,计算机网络与通信,数据通信与计算机网络咬补兆网络与通信蝗DistributedSystemDefinition强distrbutedsystem卢de57ed3500e历PizPCopMp0pe7吉atpettoAedcompUteyscomUicate30cooyoinate加ejractions0Dypassingess5ages,。Ourinterestindistributedsystemsinvolves。designandimplement
2、ation,maintenanceystudy,algorithmic“COIp07e0t=aprocessonadevice(PC,PDA)*copymupjcatea0dcooydinate=WiredorwirelessnetworkL雹荤0far.AbstractdistributedsystemcollectionofprocessesoveracommunicationmediumProtocolsyalgorithmsforsynchronization,snapshotsymulticast,election,mutualexclusion,failuredetectorsWi
3、llworkinapydistributedgroupofprocesses-E.g,Groupofprocessesoncomputerhosts-E.g,GroupofprocessesonPDAsFormostofthiscourse,welfocuson(1):computerhostsovertheInternet尸C逻士)灞6嘲i:标一一5Esrozstrosoaig5rTheInternet(InternetMappingProject,colorcodedbyISPs),网络类型RangeBandWwidthLatency个LocalArea1-2km【10-1000Mbp#1
4、-10msNetwork(LANJ)个WideArealeroeregions|、0:01-600|100-500Network(WANJ)单MetroArea一25011500Network(MAN)究WirelessLAN【0.15-1.5|2-115-20空WirelessWAN|worldwide|0.01-2100-500命Internetwork|wondwide|0o1-2|100-500_NetW0k|ngIssuesforDSP蓦f0manCeconsidertworoutersconnectedby3ink。Latencyoverthecommunicationlink*P
5、ropagationdelay(L:thetimeittakesforthefirstbitofapackettoreachthedestination*Datatransferrate(packetdelay=Lt+packetsize/仁。Othercomponentsoflatency*Processingdelay:thetimeitakesforthe0Stoprocess/send/recevethemessage,*Queuingdelay:thetimeitakesamessagetobequeuedeither不endhostsorintermediatenodeswhile
6、waitingfortransmission.。Bandwidth;thetotalamountofinformationthatcanbetransmittedoveragiventime,Expressedasmessages/secondorbytesperSecond_NetW0kmgPrinciples邦witchingSchemesaBroadcast(overaLAN)。E.g.,IEEE802.3-CSMACD(CarrierSenseMultipleAccesswithCollisionDetection)。E.g.;IEEE-802.118bzg-1WLANaCircuit
7、SWitching:aPhysicalcircuitisestablishedfromthecallertothecalleebeforecommunicationtakesplace.。E.g.,POTS-plainOldTelephoneSystemaPacketSWwitching(a.k,a.store-and-forward):packetsthatarriveatanodearefirststoredatthenodeandthenforwardedtowardtheirdestinations.。E.g,IPv4/IPv6-InternetProtocola“Circuitand
8、PacketswitchingincurtheLt+pktsize/Trcostoneacfhop(becauseeachhopstoresandforwardsentirepacket)_NetW0kingPrinciples虫SwitchingSchemesa_FrameRelay:Similartostore-and-forward,butintermediatenodesrouteframesbasedontheirfirstfew_bits.IFramesasawholearenotstoredatnodesbutpassthrough.thenodesasshortstreamso
9、fbits.aE.g.,ATMNetworks(AsynchronousTransferMode)aFrameRelayincursonlyadditionalLtlatencyoneachhop.Packetsize/Trcostincurredoverentirepath(withTr=minimumoflinktransmissionspeedsalongthepath)OSIlcOpenSystemsInterconnecton_雹_辜OtS吾7-LayerProtocolMode|-Specifiesthesequenceofmessagestobeexchanged-SPRR888
10、当8邹ImatofdatainmessagesssssseveO0S1LayeredProtocolModelCommunicationChannelHeaderaddedateachlayerHeaderstippedaleachlaye7-LayerProtocolSummary一媒Descriplon-en咤aPoocokttarasdesierelomestilecommunisatonequiementsofHTPFTPSVTP、specificapplicatonsofendcfiningheingertacetoasemeeCORSAIIOPPesenttonPooteolsat
11、hislewelmansnmitdutainanetyortrepesenationhatisSecueSocteindependentoferepresengationssedinindiiidualcompuerswhichmay“(SSDJCORBADatadifterEnenptonisakoperbnnedinthislayerifrequieiEepSesionALhislevelmelabiigandadupationareperlomnedsuchsdeteetonoftiluresandautonateeeoventTnnypotThisishelowesleelatwhic
12、hmesages(raherlanpaetelJarshandiedTCP.UDPMessgesameaddressediocommunicalonporkattcledlepmcessesProiocolsinthislayermaybecommeetononentedorconmectionlessNeatkTnansferdutapaetesbetweencomputesinaspesifeneyodkInaWAN“IP.AIMvintaaloraniniemeyortkisinvovesoutingthemestehouttcieuisuler(basedonIPaddresesJ.I
13、nasingleLANnomoutigismetinedDaalinkResponsibleforinnsmissionofpectesbetweennodesliataredieelyEliemetMACconpeciedyaphysicallinkUiesACaddresesATMeqllinnsterBetweenpaisefroulerorpaiofhostsPPPPoysicalThccinouitsandhardwarshatdrvehenctwortUnsmissequeneesefElheretbasebandbinarydutbyanloguesignaling.usingamplitudeorficqueneymodulatonefeiecticalignalsoneablecieuisHehtsienals(onfbropteciieuie)SeallngSDNorolherelectomatnetcsitnaknmadilandmicmwavecit
