I have a working DirectAccess (DA) NLB cluster in IGMP Multicast mode on vsphere 5.5. The external interface is IPv4 only (using IPHTTPS) but the internal interface is IPv4 and IPv6.
For IPv4 resources the NAT64 is acting as a proxy and therefore the IPv4 and MAC addresses used are the unicast addresses of the DA server serving that DA client.
For IPv6 resources the DA server is acting as a router. Therefore, the traffic from the resource back to the DA client uses the IPv6 unicast VIP adres of the internal cluster and this one is tied to the multicast MAC address of this cluster. It's this traffic that is flooded by de vswitch to all host on the same subnet as the internal interface of the DA Cluster.
The cluster runs in IGMP Multicast mode. A network monitor trace shows that de DA servers sends indeed IGMP Membership Reports. However, IGMP is an IPv4 technology and I don't find ICMPv6 MLD(MulticastListener Discovery) messages in those traces.
The question is therefore: how could we make it work without that IPv6 traffic flooding in the internal network? Is there a specific configuration needed, either in the vsphere environment or the NLB Cluster?
Best Regards,
Stefaan