'Configure iptables rules for prefix delegated subnets'

def _process_pd_iptables_rules(self, prefix, subnet_id):

    ext_scope = self._get_external_address_scope()
    ext_scope_mark = self.get_address_scope_mark_mask(ext_scope)
    ex_gw_device = self.get_external_device_name(self.get_ex_gw_port()['id'])
    scope_rule = self.address_scope_mangle_rule(ex_gw_device, ext_scope_mark)
    self.iptables_manager.ipv6['mangle'].add_rule('scope', (('-d    %s    ' % prefix) + scope_rule), tag=('prefix_delegation_%s' % subnet_id))
