def _attach_dummy_intf_rtr(self, tenant_id, tenant_name, rtr_id):
        """Function to create a dummy router and interface. """
        serv_obj = self.get_service_obj(tenant_id)
        fw_dict = serv_obj.get_fw_dict()
        fw_id = fw_dict.get('fw_id')
        rtr_nwk = fw_id[0:4] + fw_const.DUMMY_SERVICE_NWK + (
            fw_id[len(fw_id) - 4:])
        net_id, subnet_id = self.os_helper.create_network(
            rtr_nwk, tenant_id, self.servicedummy_ip_subnet)
        if net_id is None or subnet_id is None:
            return None, None
        net_dict = {}
        net_dict['name'] = rtr_nwk
        self.store_net_db(tenant_id, net_id, net_dict, 'SUCCESS')
        subnet_lst = set()
        subnet_lst.add(subnet_id)
        if rtr_id is None:
            self.os_helper.delete_network(rtr_nwk, tenant_id, subnet_id,
                                          net_id)
            return None, None
        ret = self.os_helper.add_intf_router(rtr_id, tenant_id, subnet_lst)
        if not ret:
            self.os_helper.delete_network(rtr_nwk, tenant_id, subnet_id,
                                          net_id)
            return None, None
        return net_id, subnet_id
Function to create a dummy router and interface.