A method including: receiving a flow; for each interface in the plurality of interfaces, determining the preference of the interface for the flow; when only a single interface has a preference for the flow, assigning the flow to that single interface; when multiple interfaces having a preference for the flow have comparable headroom, assigning the flow to the interface of the multiple interfaces with the fewest flows currently assigned to it; and when multiple interfaces having a preference for the flow do not have comparable headroom, assigning the flow to the interface within the multiple interfaces having a preference for the interface that has the greatest headroom.