Each scenario listed above falls within one of three transitional technology categories; native dual stack, tunneling, and translation [7]. Since, IPv4 address exhaustion is inevitable, IPv4 extension technologies must also be considered a co-existent technology. One important item to keep in mind in regards to IPv4 address extension technologies is it should ultimately lead to the retiring of IPv4 use and adoption of IPv6. The diagram (Figure 5) below shows the transitional/co-existence technology "lanes".