code: def on_peer_down(self, peer):
          
          LOG.debug('Cleaning obsolete paths whose source/version: %s/%s',
                    peer.ip_address, peer.version_num)
          # Launch clean-up for each global tables.
          self._table_manager.clean_stale_routes(peer)
docs: Peer down handler.
  
          Cleans up the paths in global tables that was received from this peer.