An in-depth look at flow aggregation for efficient quality of service

We investigate the preservation of quality of service guarantees to a flow of packets in the presence of flow aggregation. For efficiency, multiple flows, known as the constituent flows, are merged together resulting in a single aggregate flow. Packet schedulers located after the network point where the aggregation occurred are aware of the aggregate flow, but are unaware of its constituent flows. In spite of this, we show that quality of service guarantees may still be offered to the constituent flows provided the aggregation is performed fairly. In earlier work, we showed that the end-to-end delay is preserved (and in some cases improved) under flow aggregation, when the packet delay is coupled with the reserved rate of the flow. We go beyond these results by showing that, even when the delay is de-coupled from the reserved rate, the end-to-end delay is preserved under flow aggregation.