A High-Speed Robust Tunnel Using Forward Erasure Correction in Segment Routing

Low-latency applications drive an increasing number of modern applications. Latency depends on factors such as link layer technologies and how higher-layer protocols cope with transmission errors and packet losses. Most transport protocols rely exclusively on retransmissions to cope with losses with minimal overhead but potentially large tail latency. This paper leverages network coding to propose the high-speed robust tunnel (HIRT), providing timely packet delivery to any application independently of the transport protocol. A network code recovers lost data without requiring time-consuming retransmissions by adding redundancy packets, thereby slightly increasing the bandwidth usage to reduce the tail latency. Our algorithm dynamically adapts the rate of redundancy packets by measuring the network loss patterns. We implement HIRT using IPv6 Segment Routing (SRv6). We suggest an efficient software implementation and demonstrate on CloudLab that our solution can protect traffic at high speeds ($>50 \text{Gbps}$) on standard servers even when facing severe packet losses in the network. We evaluate HIRT with HTTP over TCP/QUIC, and file system benchmarks over a real network with losses, Starlink. HIRT reduces the tail latency of short HTTP requests by $2 \times$ and the mean request completion time of longer requests by up to $20 \%$. HIRT also decreases the tail latency of NFS requests by up to $20 \%$.