Impact of ACK Scaling Policies on QUIC Performance

Abstract

This work examines the behavior and impact of key protocol features like acknowledgment policy, different congestion control algorithms and the two levels of flow control on performance of the novel transport protocol QUIC. Each of the aforementioned protocol components adds significant complexity to the logic for sending and processing packets. Specific, suboptimal network conditions bring up new unsolved issues and can significantly lower the throughput of QUIC. One of the open issues is how to adapt the acknowledgment policy to a wide variety of network conditions. The ACK frequency frame scheme is a protocol extension proposed by Iyenguar et al. aiming at improving this mechanism by dynamically adapting the ACK ratio. To validate this proposal, we extended our existing QUIC implementation in OMNET++/INET, specifically by adding alternative congestion control algorithms as well as an implementation of the ACK frequency frame proposal. This paper presents a comparative evaluation of the ACK frequency frame proposal with a proposal, which we already introduced in previous work. Furthermore, it assesses the performance impact of this extension on the processing of the New Reno and Cubic congestion controls. It introduces simulation results how integration of Flow Control, ACK delay timer and PING frame influence an efficient ACK processing strategy, affecting the QUIC protocol performance.