The Interaction of Forward Error Correction and Active Queue Management

This paper studies the interaction of a forward error correction (FEC) code with queue management schemes like Drop Tail (DT) and RED. Since RED spreads randomly packet drops, it reduces consecutive losses. This property makes RED compatible a priori with the use of FEC at the packet level. We show, through simulations, that FEC combined with RED may indeed be more efficient than FEC combined with DT. This however depends on several parameters like the burstiness of the background traffic, the FEC block size and the amount of redundancy in a FEC block. We conclude generally that using FEC is more efficient with RED than with DT when the loss rate is small, a relatively important amount of redundancy and at most a moderate FEC block size is used. We complement these observations with a simple model, which is able to capture the tradeoff between the locality and the frequency of losses.