[CentOS] ip6tables forwarding rule

I have 2 boxes that act as IPv6 routers. One with 2 physical interfaces, the other with 6 vlan 'interfaces' on one physical interface plus a second physical interface. On both systems I have in /etc/sysconfig/network

IPV6FORWARDING=yes

But if I have my 'basic' ip6tables service running, only ICMP messages get through. Since both of these boxes are Centos based, I can't use the new shorewall6 that requires at least FC9 (both boxes have shorewall for IPv4 routing controls).

Is there a 'simple' rule to add to forward all IPv6 traffic between the interfaces, with the other rules only impacting traffic for each host itself?