L3 (Routing) traffic is not working for dual router configuration  in dual stack network.

IPv4 subnets are part of one router (Internal VPN1)

IPv6 subnets are part of second router (Internal VPN2)

Ping between IPv6 address(Different network) as well as IPv4 is not working due to table 17 is not properly programming IPv4 and IPv6 L3 service.

Please find the below sample configuration.

neutron net-create Net1
neutron net-create Net2

neutron subnet-create Net1 11.1.2.0/24 --enable-dhcp --name subnet-ipv4s1
neutron subnet-create Net2 12.23.34.0/24 --enable-dhcp --name subnet-ipv4s2

neutron subnet-create Net1 2001:db8:abcd:0011::/64 --ip-version 6 --ipv6-ra-mode slaac --ipv6-address-mode slaac --name subnet-ipv6s1
neutron subnet-create Net2 2025:caf:3214:0012::/64 --ip-version 6 --ipv6-ra-mode slaac --ipv6-address-mode slaac --name subnet-ipv6s2

neutron router-create R1
neutron router-create R2

neutron router-interface-add R1 subnet-ipv4s1
neutron router-interface-add R1 subnet-ipv4s2

neutron router-interface-add R2 subnet-ipv6s1
neutron router-interface-add R2 subnet-ipv6s2

neutron port-create Net1 --name PORT1-N1

neutron port-create Net2 --name PORT1-N2

nova boot --flavor m1.tiny --image cirros-0.3.5-x86_64-disk --nic port-id=$(neutron port-list | grep PORT1-N1 |awk '{print $2}') Host1-N1 --availability-zone nova:osc-pike-ubuntu16

nova boot --flavor m1.tiny --image cirros-0.3.5-x86_64-disk --nic port-id=$(neutron port-list | grep PORT1-N2 |awk '{print $2}') Host1-N2 --availability-zone nova:osc-pike-ubuntu16