FlEC: Enhancing QUIC with application-tailored reliability mechanisms

TL;DR

This paper introduces FlEC, a flexible erasure correction framework integrated into QUIC, enabling applications to choose tailored reliability mechanisms like retransmissions or FEC, resulting in improved latency performance.

Contribution

The paper presents a novel, generic FEC-based reliability framework inside QUIC that allows applications to select suitable loss recovery strategies, bridging a gap in existing protocols.

Findings

FlEC outperforms standard QUIC in latency across various scenarios.

Application-aware reliability mechanisms improve loss recovery.

Flexible erasure correction benefits delay-sensitive and buffer-constrained applications.

Abstract

Packet losses are common events in today's networks. They usually result in longer delivery times for application data since retransmissions are the de facto technique to recover from such losses. Retransmissions is a good strategy for many applications but it may lead to poor performance with latency-sensitive applications compared to network coding. Although different types of network coding techniques have been proposed to reduce the impact of losses by transmitting redundant information, they are not widely used. Some niche applications include their own variant of Forward Erasure Correction (FEC) techniques, but there is no generic protocol that enables many applications to easily use them. We close this gap by designing, implementing and evaluating a new Flexible Erasure Correction (FlEC) framework inside the newly standardized QUIC protocol. With FlEC, an application can easily select the reliability mechanism that meets its requirements, from pure retransmissions to various forms of FEC. We consider three different use cases: $(i)$ bulk data transfer, $(ii)$ file transfers with restricted buffers and $(iii)$ delay-constrained messages. We demonstrate that modern transport protocols such as QUIC may benefit from application knowledge by leveraging this knowledge in FlEC to provide better loss recovery and stream scheduling. Our evaluation over a wide range of scenarios shows that the FlEC framework outperforms the standard QUIC reliability mechanisms from a latency viewpoint.