'Broadcast upwards that bw_usage was updated.'

def bw_usage_update_at_top(self, ctxt, uuid, mac, start_period, bw_in, bw_out, last_ctr_in, last_ctr_out, last_refreshed=None):

    bw_update_info = {'uuid': uuid, 'mac': mac, 'start_period': start_period, 'bw_in': bw_in, 'bw_out': bw_out, 'last_ctr_in': last_ctr_in, 'last_ctr_out': last_ctr_out, 'last_refreshed': last_refreshed}
    self.client.cast(ctxt, 'bw_usage_update_at_top', bw_update_info=bw_update_info)
