A Little Project on IPv4 to IPv6

This is a Packet Tracer activity. A file is attached to understand my requirements clearly. 50% configuration is done, and need help to solve the other half of this project. A Network Topology named as "Transition from IPv4 to IPv6. Five Routers in center connected each other I assume as ISP or whatever you can think of it. If you can see into topology, I have built five sections of different networks 2 for IPv4 and 3 for IPv6. I have already Implemented IPv4 networks with DHCP server Installed and Standby Router is configured, and both sides are connected to each other and getting an IP address from DHCP server and do communicate to each other. I have also configured all section of IPv6 networks and created tunnels over IPv4, but I am unable to ping IPv6 to v6 and IPv4 to IPv6. 1- DNS, web, and FTP servers need to configure to any network, but should be accessed from both IPv4 and IPv6 networks. 2- Based on IPv4 network, IPv6 networks should be implemented by using (First choice I did it, but have some issue) tunneling technique. You can use GRE for tunneling and NAT64 for transition purpose to communicate from v6 to v4. If this does not work, (Second choice) Dual Stick technique can be applied.. For IPv6 section of Networks, there is No need to configure DHCP server, but auto- configuration should be implemented to IPv6 networks As a result of implementation of both networks, IPv6 networks should communicate with IPv4 networks and IPv4 networks should communicate with IPv6 networks. Whatever I understood so far, I just explained to you. If there is something wrong with this Topology, please advise me in advance and a different way to solve the issue.