CyclicSim: Comprehensive Evaluation of Cyclic Shapers in Time-Sensitive Networking

TL;DR

This paper provides a comprehensive evaluation of cyclic shapers in Time-Sensitive Networking, introducing a new simulation framework and analyzing their performance in various network scenarios.

Contribution

It introduces an open-source simulation framework for CQF, CSQF, and MCQF, and offers the first thorough performance comparison of these cyclic shapers.

Findings

MCQF supports diverse timing requirements.

CSQF often results in larger delays and jitter.

CSQF shows limited advantages in TSN networks with low propagation delays.

Abstract

Cyclic Queuing and Forwarding (CQF) is a key Time-Sensitive Networking (TSN) shaping mechanism that ensures bounded latency using a simple gate control list (GCL). Recently, variants of CQF, including Cycle Specific Queuing and Forwarding (CSQF) and Multi Cyclic Queuing and Forwarding (MCQF), have emerged. While popular TSN mechanisms such as the Time-Aware Shaper (TAS), Asynchronous Traffic Shaper (ATS), Credit-Based Shaper (CBS), and Strict Priority (SP) have been extensively studied, cyclic shapers have not been thoroughly evaluated. This paper presents a comprehensive analysis of CQF, CSQF, and MCQF, providing insights into their performance. We quantify delays through simulations and quantitative analysis on both synthetic and realistic networks. For the first time, we introduce an open-source OMNeT++ and INET4.4 based framework capable of modeling all three cyclic shaper variants. Our tool facilitates the validation of new algorithms and serves as a benchmark for cyclic shapers. Our evaluations reveal that MCQF supports diverse timing requirements, whereas CSQF, with its additional queue, often results in larger delays and jitter for some TT flows compared to CQF. Additionally, CSQF does not demonstrate significant advantages in TSN networks where propagation delays are less critical than in wide-area networks (WANs).