Vermilion: A Traffic-Aware Reconfigurable Optical Interconnect with Formal Throughput Guarantees

2025-04-14

AI Summary

To address bottlenecks in reconfigurable optical networks—including degraded worst-case throughput, high congestion-control overhead, and deployment complexity—caused by multi-hop routing, this paper proposes a hop-free, periodically reconfigurable optical network architecture. Our method introduces (1) a novel short-period traffic-aware scheduling mechanism, coupled with matrix rounding to generate near-optimal periodic lightpath tables; and (2) a seamless periodic table-switching strategy that handles residual traffic, eliminating reconfiguration gaps and obviating dependency on congestion control. We theoretically prove a ≥33% improvement in worst-case throughput. Experiments under typical datacenter workloads demonstrate microsecond-scale end-to-end latency, strong determinism, and significant performance gains over baselines such as RotorNet. The architecture fully circumvents the performance degradation and operational complexity inherent to multi-hop routing.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Search and Optimization: Combinatorial Optimization
• Computer Vision: Learning & Optimization for CV

Application Category

• Responsible Web: Human-perceived consequences of algorithmic deployment on the web
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems
• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization

Abstract

The increasing gap between datacenter traffic volume and the capacity of electrical switches has driven the development of reconfigurable network designs utilizing optical circuit switching. Recent advancements, particularly those featuring periodic fixed-duration reconfigurations, have achieved practical end-to-end delays of just a few microseconds. However, current designs rely on multi-hop routing to enhance utilization, which can lead to a significant reduction in worst-case throughput and added overhead from congestion control and routing complexity. These factors pose significant operational challenges for the large-scale deployment of these technologies. We present Vermilion, a reconfigurable optical interconnect that breaks the throughput barrier of existing periodic reconfigurable networks, without the need for multi-hop routing -- thus eliminating congestion control and simplifying routing to direct communication. Vermilion adopts a traffic-aware approach while retaining the simplicity of periodic fixed-duration reconfigurations, similar to RotorNet. We formally establish throughput bounds for Vermilion, demonstrating that it achieves at least $33%$ more throughput in the worst-case compared to existing designs. The key innovation of Vermilion is its short traffic-aware periodic schedule, derived using a matrix rounding technique. This schedule is then combined with a traffic-oblivious periodic schedule to efficiently manage any residual traffic. Our evaluation results support our theoretical findings, revealing significant performance gains for datacenter workloads.

Problem

• Improves throughput in reconfigurable optical interconnects
• Eliminates multi-hop routing and congestion control
• Ensures formal throughput guarantees for datacenter traffic

Innovation

• Traffic-aware periodic schedule using matrix rounding
• Combines traffic-aware and traffic-oblivious schedules
• Direct communication eliminates multi-hop routing overhead