  OPC UA is an industry-standard machine-to-machine communication protocol in
the Industrial Internet of Things. It relies on time-sensitive networking to
meet the real-time requirements of various applications. Time-sensitive
networking is implemented through various queueing disciplines (qdiscs),
including Time Aware Priority, Multiqueue Priority, Earliest TxTime First, and
Credit-Based Shaper. Despite their significance, prior studies on these qdiscs
have been limited to a few. They have often been confined to point-to-point
network topologies using proprietary software or specialized hardware. This
study builds upon existing research by evaluating all these qdiscs in
point-to-point and bridged topologies using open-source software on commercial
off-the-shelf hardware. We first identify the optimal configuration for each
qdisc and then compare their jitter, latency, and reliability through
experiments. Our results show that open-source OPC UA on commercial
off-the-shelf hardware can effectively meet the stringent real-time
requirements of many industrial applications and provide a foundation for
future research and practical deployments.
