5、eenverymature.However,duetoitsownlimitations,hasbeengraduallyexposedthemanyproblemsandshortcomings.Oneofthemost prominentis theaddressspaceofIP willbeexhausted and themainroutingtable growingproblemtherefore,IETFIPv6wasdesignedtoreplaceIPv4.Asthenextgeneration InternetProtocol IPV6, compared
6、toIPV4hasthefollowing characteristics: simplified header and extension; big enough address space and hierarchy address architecture; Plug and Play internet working; authentication and encryption on network layer; support on service quality; better support on mobile communication. IPv6will re
7、placeIPv4.TheentirenetworkfromIPv4transitiontoIPv6needforalongtime,thetwonetworkswillcoexistforalongtimeinthefuture.SoexploretheIPv4andIPv6connectivityandtransitiontechnologyhasimportantsignificance.Thispaper introduces thedisadvantagesofIPv4, and