Routers employ queues to temporarily hold packets when the scheduler cannot
immediately process them. Congestion occurs when the arrival rate of packets
exceeds the processing capacity, leading to increased queueing delay. Over
time, Active Queue Management (AQM) strategies have focused on directly
draining packets from queues to alleviate congestion and reduce queuing delay.
On Programmable Data Plane (PDP) hardware, AQMs traditionally reside in the
Egress pipeline due to the availability of queue delay information there. We
argue that this approach wastes the router's resources because the dropped
packet has already consumed the entire pipeline of the device. In this work, we
propose ingress Random Early Detection (iRED), a more efficient approach that
addresses the Egress drop problem. iRED is a disaggregated P4-AQM fully
implemented in programmable data plane hardware and also supports Low Latency,
Low Loss, and Scalable Throughput (L4S) framework, saving device pipeline
resources by dropping packets in the Ingress block. To evaluate iRED, we
conducted three experiments using a Tofino2 programmable switch: i) An in-depth
analysis of state-of-the-art AQMs on PDP hardware, using 12 different network
configurations varying in bandwidth, Round-Trip Time (RTT), and Maximum
Transmission Unit (MTU). The results demonstrate that iRED can significantly
reduce router resource consumption, with up to a 10x reduction in memory usage,
12x fewer processing cycles, and 8x less power consumption for the same traffic
load; ii) A performance evaluation regarding the L4S framework. The results
prove that iRED achieves fairness in bandwidth usage for different types of
traffic (classic and scalable); iii) A comprehensive analysis of the QoS in a
real setup of a DASH) technology. iRED demonstrated up to a 2.34x improvement
in FPS and a 4.77x increase in the video player buffer fill.Comment: Preprint (TNSM under review