differentphaseinthewaycomputernetworkswereused.Whenthefirsteditionappearedin1980,networkswereanacademiccuriosity.Whenthesecondeditionappearedin1988,networkswereusedbyuniversitiesandlargebusinesses.Whenthethirdeditionappearedin1996,computernetworks,especiallytheInternet,hadbecomeadailyrealityformillionsofpeople.Bythefourthedition,in2003,wirelessnetworksandmobilecomputershadbecomeco妹妹onplaceforaccessingtheWebandtheInternet.Now,inthefifthedition,networksareaboutcontentdistribution(especiallyvideosusingCDNsandpeer-to-peernetworks)andmobilephonesaresmallcomputersontheInternet.NewintheFifthEditionAmongthemanychangesinthisbook,themostimportantoneistheadditionofProf.DavidJ.Wetherallasaco-author.Davidbringsarichbackgroundinnetworking,havingcuthisteethdesigningmetropolitan-areanetworksmorethan20yearsago.HehasworkedwiththeInternetandwirelessnetworkseversinceandisaprofessorattheUniversityofWashington,wherehehasbeenteachinganddoingresearchoncomputernetworksandrelatedtopicsforthepastdecade.Ofcourse,thebookalsohasmanychangestokeepupwiththe:ever-changingworldofcomputernetworks.AmongthesearerevisedandnewmaterialonWirelessnetworks(802.12and802.16)The3GnetworksusedbysmartphonesRFIDandsensornetworksContentdistributionusingCDNsPeer-to-peernetworksReal-timemedia(fromstored,streaming,andlivesources)Internettelephony(voiceoverIP)Delay-tolerantnetworks
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