code: def _notify_cfg_agent_port_update(resource, event, trigger, **kwargs):
      
      original_port = kwargs.get('original_port')
      updated_port = kwargs.get('port')
      if (updated_port is not None and original_port is not None and (
         updated_port.get('admin_state_up')) != (
             original_port.get('admin_state_up'))):
          new_port_data = {'port': {}}
          new_port_data['port']['admin_state_up'] = (
              updated_port.get('admin_state_up'))
          original_device_owner = original_port.get('device_owner', '')
          if original_device_owner.startswith('network'):
              router_id = original_port.get('device_id')
              context = kwargs.get('context')
              l3plugin = bc.get_plugin(L3_ROUTER_NAT)
              if l3plugin and router_id:
                  l3plugin._notify_port_update_routers(context, router_id,
                                                       original_port,
                                                       new_port_data,
                                                       'update_port_status_cfg')
docs: Called when router port/interface is enabled/disabled