A network switch includes a transmit queue of packets along with indication (e.g. in respective status words) of the type of each packet and its size. An arbitrator includes a counter which is incremented by the size (e.g. in bytes) of each packet of a first type (e.g. `low-loss`) and decremented by a scaled size of each packet of a second type (e.g. `normal loss`). If the queue exceeds a set limit, preferably less than the maximum possible size of the queue, packets are discarded if a scaled packet of the second type exceeds the net content of the counter.