'Create database models for an IPAM subnet.
This method creates a subnet resource for the IPAM driver and
associates it with its neutron identifier, if specified.
:param context: neutron api request context
:returns: the idenfier of created IPAM subnet'

def create(self, context):

    if (not self._ipam_subnet_id):
        self._ipam_subnet_id = uuidutils.generate_uuid()
    ipam_objs.IpamSubnet(context, id=self._ipam_subnet_id, neutron_subnet_id=self._neutron_subnet_id).create()
    return self._ipam_subnet_id
