Unlocking Superior Performance in Reconfigurable Data Center Networks with Credit-Based Transport

The large-scale, end-to-end implementation of microsecond-switched reconfigurable data center networks (RDCNs), coupled with innovative routing and topology designs that provide continuous routes abstracting away frequent topology changes, demonstrates promise as a viable alternative to Clos networks in the post-Moore's Law era. However, the gap remains in transport performance, with current transport solutions falling short of unlocking their full performance. In this paper, we introduce Flare, a novel credit-based transport protocol that ensures reliable traffic delivery, low latency, and leverages the rapidly reconfiguring circuits of the RDCN to opportunistically route traffic over short paths, maximizing throughput. In simulations, Flare enables RDCNs to outperform Clos networks, achieving up to 1.15× higher throughput even under adversarial traffic. Additionally, it delivers up to 2× and 1.5× higher throughput than NDP and ExpressPass, and up to 10×, 15×, and 3.5× shorter flow completion time (FCT) than ExpressPass, TDTCP, and Bolt. Our testbed implementation further demonstrates the feasibility of Flare's mechanisms with programmable switches and DPDK.