code: def find_rtr_namespace(self, rout_id):
          
          if rout_id is None:
              return None
          args = ['ip', 'netns', 'list']
          try:
              ns_list = utils.execute(args, root_helper=self.root_helper)
          except Exception as exc:
              LOG.error("Unable to find the namespace list Exception %s",
                        exc)
              return None
          for ns in ns_list.split():
              if 'router' in ns and rout_id in ns:
                  return ns
docs: Find the namespace associated with the router.