code: def connection_lost(self, reason):
          
  
          if self._peer:
              state = self._peer.state.bgp_state
              if self._is_bound or state == BGP_FSM_OPEN_SENT:
                  self._peer.connection_lost(reason)
  
              self._peer = None
  
          if reason:
              LOG.info(reason)
          else:
              LOG.info('Connection to peer closed for unknown reasons.')
docs: Stops all timers and notifies peer that connection is lost.