iPIFO: A network memory architecture for QoS routers

Routers need memories to store and forward packets. More than that, routers use memories to schedule flows according to their quality-of-service (QoS) requirements. The simple first-in-first-out (FIFO) queue memory is insufficient to provide QoS guarantees. Most current routers are based on the virtual-output-queue (VOQ) memory management and use heuristic algorithms, such as iSLIP or DRRM, to schedule packets. On the other hand, push-in-first-out (PIFO) queue memory has also been proposed as a model for routers to meet the QoS requirements. The PIFO queue does not need a scheduler since packets are always first-out from the queue head. However, due to the sorting-related problems of the push-in operation, it is normally supposed impractical to build the PIFO queues in real hardware. We try to touch this problem in this paper and propose an indexed PIFO queue (iPIFO) architecture and a memory management algorithm on it. We believe it is a feasible solution to bring the PIFO queue to practice.