数据通信与网络课后习题答案上

《数据通信与网络课后习题答案上》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、CHAPTER115.With16bits,wecanrepresentupto216differentcolors.17.a.Meshtopology:Ifoneconnectionfails,theotherconnectionswillstillbeworking.b.Startopology:Theotherdeviceswillstillbeabletosenddatathroughthehub;therewillbenoaccesstothedevicewhichhasthefailedconnectiontothehub.c.BusTopology:Alltransmiss

2、ionstopsifthefailureisinthebus.Ifthedrop-linefails,onlythecorrespondingdevicecannotoperate.2d.RingTopology:Thefailedconnectionmaydisablethewholenetworkunlessitisadualringorthereisaby-passmechanism.19.Theoretically,inaringtopology,unpluggingonestation,interruptsthering.However,mostringnetworksusea

3、mechanismthatbypassesthestation;theringcancontinueitsoperation.21.SeeFigure1.123.a.E-mailisnotaninteractiveapplication.Evenifitisdeliveredimmediately,itmaystayinthemail-boxofthereceiverforawhile.Itisnotsensitivetodelay.b.Wenormallydonotexpectafiletobecopiedimmediately.Itisnotverysensitivetodelay.

4、c.SurfingtheInternetistheanapplicationverysensitivetodelay.Weexcepttogetaccesstothesitewearesearching.25.Thetelephonenetworkwasoriginallydesignedforvoicecommunication;theInternetwasoriginallydesignedfordatacommunication.Thetwonetworksaresimilarinthefactthatbotharemadeofinterconnectionsofsmallnetw

5、orks.Thetelephonenetwork,aswewillseeinfuturechapters,ismostlyacircuit-switchednetwork;theInternetismostlyapacket-switchednetwork.Figure1.1SolutiontoExercise21StationStationStationRepeaterStationStationStationRepeaterStationStationStationRepeaterHub1CHAPTER2Exercises15.TheInternationalStandardsOrg

6、anization,ortheInternationalOrganizationofStandards,(ISO)isamultinationalbodydedicatedtoworldwideagreementoninternationalstandards.AnISOstandardthatcoversallaspectsofnetworkcommunicationsistheOpenSystemsInterconnection(OSI)model.217.a.Reliableprocess-to-processdelivery:transportlayerb.Routeselect

7、ion:networklayerc.Definingframes:datalinklayerd.Providinguserservices:applicationlayere.Transmissionofbitsacrossthemedium:physicallayer19.a.Formatandcodeconversionservices:presentationlayerb.Establishing,managing,andte