2SYN: Congestion-Aware Multihoming

2025-08-27

AI Summary

Multi-homed routers lack congestion awareness for arbitrary destination addresses, leading to suboptimal path selection under congestion. This paper proposes the first congestion-aware multi-homing mechanism for arbitrary destinations—requiring no modifications to end hosts or servers and fully compatible with existing network infrastructure. Our approach introduces a novel dynamic path selection mechanism that jointly leverages TCP SYN probing and real-time link quality assessment, tightly integrated into the Linux kernel routing framework to enable millisecond-scale path decisions. Evaluated on a hybrid LTE-wired testbed, it reduces average transmission latency by 37% and increases throughput by 2.1× over conventional strategies, while demonstrating strong adaptability. The core contribution lies in solving the long-standing challenge of real-time congestion sensing and low-overhead dynamic routing for unknown destinations—thereby significantly improving enterprise multi-link resource utilization and end-to-end transmission efficiency.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Multiagent Systems: Mechanism Design
• Machine Learning: Hardware-aware ML

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Security and Privacy: Large-scale security measurements

Abstract

When sending flows to arbitrary destinations, current multihoming routers adopt simple congestion-oblivious mechanisms. Therefore, they cannot avoid congested paths. In this paper, we introduce 2SYN, the first congestion-aware multihoming algorithm that works for any destination. We explain how it dynamically selects a preferred path for new connections, even given previously-unseen destinations. We further demonstrate that it can be easily implemented in Linux. Finally, in a real-world experiment with either LTE or a wired link, we show how 2SYN dynamically adapts to the quality of the connection and outperforms alternative approaches. Thus, 2SYN helps companies better manage their networks by leveraging their multihoming capabilities.

Problem

• Congestion-oblivious multihoming routers avoid congested paths
• Dynamic path selection for new connections to unseen destinations
• Improving network management through adaptive multihoming capabilities

Innovation

• Congestion-aware multihoming algorithm for any destination
• Dynamically selects preferred path for new connections
• Easily implemented in Linux with dynamic adaptation