Abstract— The transition between the IPv4 Internet today and
the IPv6 Internet will be a long process during both protocols coexists and also it is unreasonable to expect that many millions of IPv4 nodes will be converted overnight. Mobility is becoming ubiquitous nowadays. This paper is described about a background study of IPv4 and IPv6, the needs of IPv6, transition mechanisms in the various architectures, the advantages of IPv6 and limitations and comparison of the IPv4 and IPv6 in five major areas;