Multi-Level Preemption in TSN: Feasibility and Requirements Analysis
Ref: CISTER-TR-200310 Publication Date: 19 to 21, May, 2020
Multi-Level Preemption in TSN: Feasibility and Requirements AnalysisRef: CISTER-TR-200310 Publication Date: 19 to 21, May, 2020
To overcome the limitation of strictly non-preemptive frame transmission in Ethernet networks, the IEEE802.1Qbu standard was introduced. This standard specifies a one-level frame preemption paradigm wherein, depending on their priority levels, frames are grouped into two classes: namely, the ``express frames'' and the ``preemptable frames''. These two classes are given with the interpretation that (1) only express frames can preempt preemptable frames; and (2) two frames belonging to the same class cannot preempt each other. While this approach partially solves the problem, some preemptable frames can still suffer long blocking periods, irrespective of their individual priority levels. Indeed, there are frames that do not fall into the express frames class, but nevertheless have firm timing requirements that can only be met if they can benefit from preempting lower priority frames. To ameliorate the condition of such frames, we propose a multi-level preemption paradigm. Specifically, we expose the limitations of the one-level preemption approach experimentally; and we present the feasibility and implementation requirements of the multi-level preemption scheme in details.
23rd IEEE International Symposium on Real-Time Distributed Computing (ISORC 2020), Distributed computing and communication infrastructures, pp 47-55.