#10) IPv6 follows the key design principles of IPv4, thereby permitting a smooth transition from IPv4.
IPv4 has been successfully deployed the world over for many years now and its popularity is a testament to the success of its design. IPv6 follows many of the same design features that made IPv4 so successful. This makes it possible to have a smooth transition from IPv4 to IPv6. There are many commercially attractive applications in the market today that require IPv6 and may tempt many to go in for a rapid transition to IPv6. However, IPv4 applications will be used for some time to come and the process of transition from IPv4 to IPv6 must be a gradual one.
A successful IPv4 to IPv6 transition mechanism is one in which IPv6 elements are incorporated into the network while at the same time compatibility is maintained with the pre-existing, large base of IPv4 hosts and routers. Thus, for some time to come, IPv6 hosts and routers must interact and function with the existing IPv4 network infrastructure.
A number of such transition mechanisms have been defined that allow for the two networks to co-exist till such a time that a complete migration to IPv6 is not feasible.
Using Dual IPv4/IPv6 Stack implementations such as Tunneling, Dual IPstack
Using Network Address and Protocol Translators.