Protocols connection lost handler.

def connection_lost(self, reason):
        """Protocols connection lost handler.
        """
        LOG.info(
            'Connection to peer %s lost, reason: %s Resetting '
            'retry connect loop: %s' %
            (self._neigh_conf.ip_address, reason,
             self._connect_retry_event.is_set()),
            extra={
                'resource_name': self._neigh_conf.name,
                'resource_id': self._neigh_conf.id
            }
        )
        self.state.bgp_state = const.BGP_FSM_IDLE
        if self._protocol:
            self._protocol.stop()
            self._protocol = None
            # Create new collection for initial RT NLRIs
            self._init_rtc_nlri_path = []
            self._sent_init_non_rtc_update = False
            # Clear sink.
            self.clear_outgoing_msg_list()
            # Un-schedule timers
            self._unschedule_sending_init_updates()

            # Increment the version number of this source.
            self.version_num += 1
            self._peer_manager.on_peer_down(self)

            # Check configuration if neighbor is still enabled, we try
            # reconnecting.
            if self._neigh_conf.enabled:
                if not self._connect_retry_event.is_set():
                    self._connect_retry_event.set()