In one embodiment, a node determines an overload ratio for an output as a ratio of a total rate of received traffic at the output to a preemption threshold of the output. The node also determines a ratio of traffic that is to be marked at the output based on the overload ratio and a ratio of previously marked traffic destined for the output from each input to the total traffic from each input to the output, and whether, for a particular input, the ratio of previously marked traffic is less than the ratio of traffic that is to be marked at the output. If so, the node marks unmarked traffic of the particular input corresponding to a difference between the ratio of traffic that is to be marked at the output and the ratio of previously marked traffic destined for the output from the particular input.