Flowcut Switching: High-Performance Adaptive Routing with In-Order Delivery Guarantees
Abstract
Network latency severely impacts the performance of applications running on supercomputers. Adaptive routing algorithms route packets over different available paths to reduce latency and improve network utilization. However, if a switch routes packets belonging to the same network flow on different paths, they might arrive at the destination out-of-order due to differences in the latency of these paths. For some transport protocols like TCP, QUIC, and RoCE, out-of-order (OOO) packets might cause large performance drops or significantly increase CPU utilization. In this work, we propose flowcut switching, a new adaptive routing algorithm that provides high-performance in-order packet delivery. Differently from existing solutions like flowlet switching, which are based on the assumption of bursty traffic and that might still reorder packets, flowcut switching guarantees in-order delivery under any network conditions, and is effective also for non-bursty traffic, as it is often the case for RDMA.
Cite
@article{arxiv.2506.21406,
title = {Flowcut Switching: High-Performance Adaptive Routing with In-Order Delivery Guarantees},
author = {Tommaso Bonato and Daniele De Sensi and Salvatore Di Girolamo and Abdulla Bataineh and David Hewson and Duncan Roweth and Torsten Hoefler},
journal= {arXiv preprint arXiv:2506.21406},
year = {2025}
}