The Packet Number Space Debate in Multipath QUIC

TL;DR

This paper investigates the impact of using one versus multiple packet number spaces in Multipath QUIC, showing that a per-path approach enhances resilience to acknowledgment strategies through NS3 simulations.

Contribution

It provides experimental insights into how the number of packet number spaces affects Multipath QUIC performance, addressing a key design decision.

Findings

Using one packet number space per path improves resilience.

Experimental results based on NS3 simulations.

Highlights the importance of packet number space design in Multipath QUIC.

Abstract

With a standardization process that attracted many interest, QUIC can been seen as the next general-purpose transport protocol. Still, it does not provide true multipath support yet, missing some use cases that MPTCP can address. To fill that gap, the IETF recently adopted a multipath proposal merging all the proposed designs. While it focuses on its core components, there still remains one major design issue in the proposal: the number of packet number spaces that should be used. This paper provides experimental results with two different Multipath QUIC implementations based on NS3 simulations to understand the impact of using one packet number space per path or a single packet number space for the whole connection. Our results suggest that using one packet number space per path makes the Multipath QUIC connection more resilient to the receiver's acknowledgment strategy.