Dynamic Queuing for Approximate Fairness in Programmable Shared Memory Switches

To ensure fair bandwidth allocation for diverse application flows from data centers, effective bandwidth management in switches is critical. Modern switches often adopt shared memory architectures to enhance efficiency. Fair queuing mechanisms can achieve fair bandwidth allocation in switches. However, the state-of-the-art fair queuing mechanisms in shared memory switches suffer from excessive packet drops, leading to suboptimal network utilization. In this paper, we propose Dynamic Fair Queuing (DFQ), a novel mechanism that leverages a limited number of priority queues to achieve both high network utilization and fair bandwidth allocation. DFQ is based on two key novel ideas. First, DFQ presents dynamic admission thresholds to manage packet enqueuing by monitoring the accumulated arrived packet bits and the remaining buffer of the queues in real time. Second, DFQ employs queue splitting and merging to maximize the utilization of the shared memory pool while guaranteeing fairness. Simulation results demonstrate that DFQ significantly improves throughput, fairness, and network utilization, while reducing flow completion time by up to 44.1%.