5、ctInternethasexperiencedseveraldecadesofrapiddevelopment,hasbecomeanindispensablepartoflife.AsacornerstoneoftheentirenetworkofIPv4hasbeenverymature.However,duetoitsownlimitations,hasbeengraduallyexposedthemanyproblemsandshortcomings.Oneofthemost prominentis the
6、addressspaceofIP willbeexhausted and themainroutingtable growingproblemtherefore,IETFIPv6wasdesignedtoreplaceIPv4.Asthenextgeneration InternetProtocol IPV6, comparedtoIPV4hasthefollowing characteristics: simplified header and extension; big enough address space
7、 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 replaceIPv4.TheentirenetworkfromIPv4transitiontoIPv6needforalongtim