Characterizing the Configuration of Starlink Queuing
This work reveals previously private queuing details of the Starlink access network, which is important for understanding its performance implications for end-users and congestion control algorithms.
The authors characterize Starlink's queuing configuration by developing a high-precision traffic generation method to measure one-way delay, finding that Starlink uses drop-front buffer management instead of per-flow fair queuing or drop-tail buffers, which may reduce delay but interfere with loss-based congestion controls.
In all networking systems, queuing is important to ensure appropriate resource utilization in the presence of bursty traffic and varying traffic demands. The Starlink access network is additionally also dynamic in terms of the capacity it can provide, and thus queuing plays an even greater role to ensure appropriate communication performance for the end-users while maintaining high resource utilization. However, for Starlink most system design details, along with the setup of the internal queuing, is private information and not publicly available. To address this we have developed a high-precision, burst-pattern controlled, traffic generation approach allowing us to precisely measure the one-way delay for Starlink. By analyzing the delay and loss in conjunction with a queue simulator we find that Starlink does not employ per-flow fair queuing or drop-tail buffers, but it does use drop-front buffer management. While drop-front reduces delay, it may also interfere with the assumptions made by loss-based congestion controls, potentially contributing to throughput degradation.