Pv4/IPv6 transition rolls out many challenges to the world of internet. IETF proposes various transition techniques including dual IP stack, IP translation and tunnelling transition mechanisms. The transition between the IPv4 internet and IPv6 internet will be a long process as they are completely two separate protocols. IPv4 host and routers will not be able to deal directly with IPv6 traffic and vice versa. A detailed study is made on the IPv6 addressing architecture. Out of the three mechanisms Tunnelling proves to be most effective. Tunnelling mechanism support 'link to link' IP connectivity across an 'unlike' network. The 6rd mechanism that are used for IPv4/IPv6 transition mechanism permits an Ipv6 mobile node to roam into Ipv4 based network and get serviced besides roaming in IPv6 based network. This paper aims at a comparative study on the three transition techniques such as Softwire mesh which supports Dual Stack, NAT444 which supports translation and IPv6 Rapid Development (6rd) mechanism in tunnelling mechanism.