TSN Experiments Using COTS Hardware and Open-Source Solutions: Lessons Learned

Time-Sensitive Networking (TSN) brings deterministic behavior to Ethernet-based systems, resulting in hardware and software supporting various TSN standards. Using TSN-capable Commercial off-the-Shelf (COTS) hardware and open-source software brings several challenges. These are especially visible while performing performance evaluation of various TSN standards. In this work, we present the most significant challenges we faced using such deployments. Starting with the Precision Time Protocol, we observe its implementation being incompatible with that of the Time-Aware Priority Shaper. We present several solutions on how to overcome the identified behavior and compare them proposing best fitting solution for any setup. Next, we focus on the Network Interface Cards (NICs) and their behavior in presence of various TSN standards. We observe that the hardware offload features aiming to improve performance sometimes introduce performance artifacts worthwhile of investigation. Further, even though the Credit-Based Shaper configuration parameters can theoretically be computed for various NICs, due to the internal optimization of some, the calculated parameters may not hold. Our findings are intended to help the community improve observed results and solve challenges in using the COTS hardware and open-source software. We believe additional documentation detailing the implementation aspects of TSN standards in hardware would be beneficial in explanation of observed behavior.