Supporting Deterministic Traffic on Standard NICs
Abstract
Networked mission-critical applications (e.g., avionic control and industrial automation systems) require deterministic packet transmissions to support a range of sensing and control tasks with stringent timing constraints. While specialized network infrastructure (e.g., time-sensitive networking (TSN) switches) provides deterministic data transport across the network, achieving strict end-to-end timing guarantees requires equally capable end devices to support deterministic traffic. These end devices, however, often employ general-purpose computing platforms like standard PCs, which lack native support for deterministic traffic and suffer from unpredictable delays introduced by their software stack and system architecture. Although specialized NICs with hardware scheduling offload can mitigate this problem, the limited compatibility hinders their widespread adoption, particularly for cost-sensitive applications or in legacy devices. To fill this gap, this paper proposes a novel software-based driver model, namely KeepON, to enable the support of deterministic packet transmissions on end devices equipped with standard NICs. The key idea of KeepON is to have the NIC keep on transmitting fixed-size data chunks as placeholders, thereby maintaining a predictable temporal transmission pattern. The real-time packets generated by the mission-critical application(s) will then be precisely inserted into this stream by replacing placeholders at the designated position to ensure their accurate transmission time. We implement and evaluate KeepON by modifying the network driver on a Raspberry Pi using its standard NIC. Our experiments demonstrate that KeepON can achieve x162 times scheduling accuracy comparable to its default driver, and x2.6 times compared to hardware-based solution, thus enabling precise timing control on standard commodity hardware.