Comment 1 for bug 1382076

Looks like we have more work to do in this area. Neutron allocates a gateway_ip when creating a subnet, in the same time creating allocation_pool for this subnet.

The issue with allowing fixed_ip in SLAAC subnet is that it's not possible to give this address to the VM. But this is not an issue with the gateway_ip in the case of neutron router. So the fix could be
 -- create the gateway_ip with eui64, and don't allow --gateway-ip to be specified in the case of slaac subnet.
 -- honor it, but check the owner of the IP when testing the ip address. And if the owner is the router, accept it; otherwise, error.

Consider https://review.openstack.org/#/c/101433/14 which tried to use eui64 for all the ports in a slaac subnet, but apparently the router port is missed out. Therefore solution 1 seems to be preferred.

In any case, allocation pool is not necessary to be maintained for a SLAAC subnet.