How will the public Internet, which is based on IPv4, be transitioned to IPv6.

The Public internet, based on IPv4 will be transitioned to IPv6 using three(3) strategies:

There are:

1. Dual-Stack
2. Tunnelling
3. Header Translation

The above three strategies are described briefly below:

Dual-Stack:

1.  Every System maintaining "Dual-Stack", contains IPv4 and IPv6 system together
2. Strategy steps are:

1.  Source sends an inquiry request message to DNS server for finding destination IP version system.
2. If DNS's response is IPv4, Source uses IPv4 system for sending data, otherwise, the IPv6 system is used for sending data.

Fig. Dual-Stack strategy

Tunnelling:

Ipv6 packet is encapsulated in an IPv4 packet when it enters in the IPv4 region.

Fig. Tunnelling

Here, IPv4 region acts as a tunnel.

Header Translation:

when most of the system is on IPV6 but some still use IPv4.

                                                                           

Fig. Header Translation

here, Header translation system translates the IPv6 datagram header into IPv4 datagram header for IPv4 typed client.