计算机网络复习题库带题目.docx
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计算机网络复习题库带题目
一、名词解释
1.Computernetwork:
Acollectionofautonomouscomputersinterconnectedbyasingletechnology.
2.client-servermodel:
Anetworkwithtwoclientsandoneserver.p4
itisapplicalewhentheclientandservearebothinthesamebuiding,butalsowhentheyarefarapart.Theclient-servermodelinvolvesrequestsandreplies.
3.Usesofnetworks:
(a)BusinessApplications(商业应用)(c/s模型)
(b)HomeApplications(家庭应用)
i.Accesstoremoteinformation(访问远程信息)
——Newspaperson-line(在线报纸)
——Digitallibrary(数字图书馆)
ii.Person-to-personcommunication(个人之间的访问)
——Instantmessage(即时消息)
——Chatroom(聊天室)
——Newsgroups(新闻组)
iii.Interactiveentertainment(交互式娱乐)
——Videoondemand(视频点播)
——Gameplaying(游戏)
iv.Electroniccommerce(电子商务)
——Homeshopping(在家购物)
——Accesstofinancialinstitutions(访问金融机构)
——electronicfleamarkets(电子跳蚤市场)
(c)MobileUsers(移动用户)
(d)SocialIssues(社会问题)
4.twotypesoftransmissiontechnology(两种类型的传输技术)
(1)Broadcastlinks广播式
Broadcastnetworks
ThecharacteristicofBroadcastnetworks:
Haveasinglecommunicationchannel
Shortmessagecalledpackets
Anaddressfieldwithinthepacket
Receivethepacketcheckitsaddressfieldprocessorignore
(2)Point-to-pointlinks点到点
●Point-to-pointlinks.点到点
Theoperationmode(操作模式)
Unicasting(单播):
只有一个发送方和一个接收方的点对点传输模式
Ageneralrule(一般原则):
越小的地理位置局部化的网络使用广播传输模式
大的网络使用点到点传输模式
5LAN:
theyareprivately-ownednetworkswithinasinglebuidingorcampusofuptoafewkilometersinsize.
(2)MAN:
(Ametropolitanareanetwork)itcoversacity.thebest-knownexampleofaMANisthecabletelevisionnetworkavailableinmanycities.
(3)WAN:
(Awideareanetwork)itspansalargegeographicalarea,oftenacountryorcontinent.
(4)internetwork:
Acollectionofinterconnectednetworks
6.Thecategoriesofwirelessnetworks
1.Systeminterconnection(系统互连)
2.WirelessLANs(无线LAN)
3.WirelessWANs(无线WAN)
7.IEEE802:
InstituteofElectricalandElectronicsEngineersP76
Number
Topic
802.2|
Logicallinkcontrol
802.3*
Ethernet
802.11*
WirelessLANs
802.15*
Personalareanetworks(bluetooth)
802.16*
Broadbandwireless
8.protocol,protocolstack,networkarchitecture
(1)protocol:
itisrulesbywhichprocessescommunicate
(2)protocolstack:
aretypicallybasedeitherontheOSImodelorontheTCP/IPmodel.
(3)networkarchitecture:
(陈晓雪的Protocolisanagreementbetweenthecommunicatingpartiesonhowcommunicationistoproceed.
Asetoflayersandprotocolsiscalledanetworkarchitecture.
Alistofprotocolsusedbyacertainsystem,oneprotocolperlayer,iscalledaprotocolstack.)
二.简答
1.OSIreferencemodel:
(分为哪几个层次以及每个层次的含义)P39
Itisinvolvedinsevenlayers。
1ThePhysicalLayer.ThePhysicalLayerisconcernedwithtransmittingrawbitsoveracommunicationchannel.(在通信信道上传输原始数据位。
)
2TheDataLinkLayer.ThetaskoftheDataLinkLayeristotransformarawtransmissionfacilityintoalinethatappearsfreeofundetectedtransmissionerrorstothenetworklayer.(数据链路层的主要任务是将一个原始的传输设备转变成一条逻辑的传输线路,在这条传输线路上,所有未检测出来的错误层次,也会反映到网络层上。
)
3TheNetworkLayer.ThenetworkLayercontrolstheoperationofthesubnet.(网络层控制子网的运行过程。
)
4TheTransportLayer.Thebasicfunctionofthetransportlayeristoacceptdatafromabove,splititupintosmallerunitsifneedbe,passthesetothenetworklayer,andensurethatthepiecesallarrivecorrectlyattheotherend.(传输层的基本功能是接受来自上一层的数据,并且在必要的时候把这些数据分割成小的单元,然后把数据单元传递给网络层,并且确保这些数据片段都能够正确的到达另一端。
)
5TheSessionLayer.Thesessionlayerallowsusersondifferentmachinestoestablishsessionsbetweenthem.(会话层允许不同机器上的用户之间建立会话。
)
6TheApplicationLayer.Theapplicationlayercontainsavarietyofprotocolsthatarecommonlyneededbyusers.(应用层包含了各种各样的协议。
)
7ThePresentationLayer.Thepresentationlayerisconcernedwiththesyntaxandsemanticsofthesemanticsoftheinformationtransmitted.(所传递的信息的语法和语意。
)
2.TCP/IPmodel:
Theabilitytoconnectmultiplenetworksinaseamlesswaywasoneofthemajordesigngoalsfromtheverybeging.ThisarchitecturelaterbecomeknownastheTCP/IPreferencemodel.
Itisinvolvedinfourlayers.
(1)TheInternetLayer.Theinternetlayeristhelinchpinthatholdsthewholearchitecturetogether.(将整体网络体系贯穿在一起。
)
(2)TheTransportLayer.Thetransportlayerallowspeerentitiesonthesourceanddestinationhoststocarryonaconversation.(允许源和目标主机上的对等体之间可以进行会话。
)
(3)TheApplicationLayer.Itcontainsallthehigher-levelprotocols.(它包含了所有的高层协议)
(4)TheHost-to-NetworkLayer.ItpointsoutthatthehosthastoconnecttothenetworkusingsomeprotocolsoitcansendIPpacketstoit.(它指出主机必须通过某个协议连接到网络上,以便可以将分组发送到网络上。
)
三、Problems:
18,19(P82)
18.OSI的哪一层分别处理以下问题?
把传输的比特流划分为帧——数据链路层
决定使用哪条路径通过子网——网络层.
19.question:
Iftheunitexchangeatthedatalinkleveliscalledaframeandtheexchangedatthenetworkleveliscalledapacket,doframesencapsulatepacketordopacketsencapsulateframe?
答:
帧封装包。
当一个包到达数据链路层时,整个数据包,包括包头、数据及全部内容,都用作帧的数据区。
或者说,将整个包放进一个信封(帧)里面,(如果能装入的话)。
第二章
一、名词解释
(一)、opticaltransmissionsystem(光传输系统):
hasthreekeycomponents
⏹thelightsource
⏹thetransmissionmedium
⏹thedetector
(二)、wirelesstransmission
1、TheElectromagneticSpectrum(电磁波谱)
2、*RadioTransmission:
radioiseasytogenerate,cantravellongdistances,andpenetratebuidingseasy.(无线电波很容易产生,也可以传输很长的距离,并且易于穿透建筑物。
)
3.MicrowaveTransmission(微波传输)
(1)about100MHz,thewavetravelinnearlystraightlinesandcanthereforebenarrowlyfocused.(在100MHZ以内,电波几乎按直线传播)
(2)Microwavesdonotpassthroughbuildingswell.(微波不能很好的穿透建筑物)
(3)disadvantage:
multipathfading(多路衰减),Absorbtedbywater(微波可以被水吸收)
(4)ithastwosignficentadvantagesoverfiber
a.themainoneisthatnorightofwayisneeded.
b.microwaveisalsorelativelyinexpensive.
4.InfraredandMillimeterWave(uedeforshort-rangecommunication.theyaredirectional,cheap,easytobuidandtheydonotpassthroughsolidobjict)
5.LightwaveTransmission
a)Thelaser'sstrength,averynarrowbeam,isalsoitsweaknesshere
b)Adisadvantageisthatlaserbeamscannotpenetraterainorthickfog,buttheynormallyworkwellonsunnydays.
c)Convectioncurrentscaninterferewithlasercommunicationsystems.
(三).ISM(Industrial,Scientific,Medical)
1.Industrial,Scientific,Medical(工业的、科学的、医药的)
2.allocatingfrequenciesistonotallocatethematall(频段的位置不同)
3.Justleteveryonetransmitatwillbutregulatethepowerusedsothatstationshavesuchashortrangetheydonotinterferewitheachother
(四)、telephonesystemconsistsofthreemajorcomponents
1.Localloops:
analogtwistedpairsgoingintohousesandbusinesses(本地回路,双绞线进入家庭和业务部门,模拟信号)
2.Trunks:
digitalfiberopticsconnectingtheswitchingoffices(干线,通过光纤将交换局连接起来,数字信号)
3.Switchingoffices:
wherecallsaremovedfromonetrunktoanother(交换局,电话呼叫从一条干线接入另一条干线)
(五)、1、fullduplex:
allmodernmodemsallowtrafficinbothdirectionsatthesametime(byusingdifferentfrequenciesfordifferentdirections).Aconnectionthatallowstrafficinbothdirectionssumultaneouslyiscalledfullduplex.Atwo-laneroadisfullduplex
2.halfduplex:
Aconnectionthatallowstrafficeitherway,butonlyonewayatatimeiscalledhalfduplex.Asinglerailroadtrackishalfduplex.
3.simplex:
Aconnectionthatallowstrafficonlyonewayiscalledsimplex.
(六).Multiplexing:
FDMandTDM(P137)
1.Multiplexing(multiplexingmanyconversationsoverasinglephysicaltrunk).(用于一条物理干线上尽可能的并发传输多个会话)
2.FDM(FrequencyDivisionMultiplexing)(频分多路复用)
3.TDM(TimeDivisionMultiplexing)(时分多路复用)
(七)、switching:
circuitswitchingandpacketswitching(交换,电路交换和报文交换)(P147、P150)
1.ThedifferencebetweenPacketSwitchingandCircuitSwitching
⏹circuitswitchingrequiresthatacircuitbesetupendtoendbeforecommunicationbegins.Packetswitchingdoesnotrequireanyadvancesetup.
⏹Packetswitchingismorefaulttolerantthancircuitswitching.
⏹Settingupapathinadvancealsoopensupthepossibilityofreservingbandwidthinadvance.
⏹congestioncanoccuratdifferenttimeswithcircuitswitching(atsetuptime)andpacket
⏹Packetswitchingdoesnotwastebandwidthandthusismoreefficient
⏹Packetswitchingusesstore-and-forwardtransmission.
⏹circuitswitchingiscompletelytransparent.
⏹thechargingalgorithm
2.Acomparisonofcircuit-switchedandpacket-switchednetworks
3.messageswitching:
store-and-forwardnetwork
二、简答
1、Modulation(threekindsofModulation)?
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陈晓雪的
答案:
Therearethreebasictypesofmodulation:
amplitudemodulation(AM)variesthevoltage;frequencymodulation(FM)variesthefrequency,andphasemodulation(PM)variestheangleofthewave(seeamplitudemodulation,frequencymodulationandphasemodulation).Inquadratureamplitudemodulation(QAM),boththeamplitudeandphaseofthecarrieraremodified(seeQAM)。
第三章
一、简答
(一)、Thefunctionofdatalinklayer(数据链路层的功能)
答案:
Thespecificfunctionsitcancarryout
1.Providingawell-definedserviceinterfacetothenetworklayer.
2.Dealingwithtransmissionerrors.
3.Regulatingtheflowofdatasothatslowreceiversarenotswampedbyfastsenders.
(二)、fourmethodsofframing(四种成帧方法)P188—P190
1.Charactercount.字符计数法。
2.Flagbyteswithbytestuffing.含字节填充的分界符法。
3.Startingandendingflags,withbitstuffing.含位填充的分界标志法。
4.Physicallayercodingviolations物理层编码违例法。
(三)、Hammingcode计算题P195
(四)、CRC计算题P197—P198
(五)、Slidingwindowprotocols(滑动窗口协议)?
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P211--P213
1、Dataframeandacknowledgementframe
(1)twoseparatephysicalcircuits
(2)usethesamecircuitfordatainbothdirections
(3)Piggybacking
(4)Acknowledgementscanbehookedontothenextoutgoingdataframe
2、sendingwindow
thesendermaintainsasetofsequencenumber