TIMER_INTERVAL
if ((t % TIMER_INTERVAL) == 0)
virtual_time += TIMER_INTERVAL;
if ((r->rt_timer += TIMER_INTERVAL) < ROUTE_EXPIRE_TIME) {
if ((r->rt_leaf_timers[vifi] -= TIMER_INTERVAL) == 0){
if (v->uv_leaf_timer && (v->uv_leaf_timer -= TIMER_INTERVAL == 0)) {
if ((a->al_timer += TIMER_INTERVAL) < NEIGHBOR_EXPIRE_TIME)