For instance, none of the VMs we operate (which all have an IPv6 /64 assigned) have real network hardware, so it makes no sense to generate the IPv6 address from a MAC there.
But each vNIC does have a subnet-unique MAC address, right? Why not use it?
And you can still multihome a single IPv6 address across more than one physical interface, so again, that's not somewhere you'd want to put a MAC into an IP address.
As long as you break the tie deterministically, I don't see the harm in picking one of the interface MACs.
> But each vNIC does have a subnet-unique MAC address, right? Why not use it?
Why use it at all? If it's not related to a real, physical item (and maybe you don't make any guarantees about MAC uniqueness across VM clusters), it's pointless bureaucracy.
> As long as you break the tie deterministically, I don't see the harm in picking one of the interface MACs.
Again, why would you bother to do this? If you've picked one of the NICs as "blessed", you're one hardware replacement (or network reconfiguration) from neither being blessed - so why not just assign in sequence from whatever netblock you're dealing with to start off with, and ignore the hardware?
But each vNIC does have a subnet-unique MAC address, right? Why not use it?
And you can still multihome a single IPv6 address across more than one physical interface, so again, that's not somewhere you'd want to put a MAC into an IP address.
As long as you break the tie deterministically, I don't see the harm in picking one of the interface MACs.