Let’s imagine that we call the IPv6 address of Google’s DNS server on the cmd console:
The cmd console is working on my PC, which is connected with the router. The source address is the global IPv6 address of my PC and the destination address is the global IPv6 address of Google’s DNS server.
The request is going out of my router. Thus, he remembers the request. The next station of the IP package is the DNS server. The server addresses the packages to the router. The destination address is the global IPv6 address of my PC. The incoming packages to the router will be proved by its firewall. Due to the fact that the router remembered the request, its firewall will let the packages go to my PC. Now, I am able to call Google’s DNS server via IPv6.