TSN-VM: A Real-time and Distributed Algorithm for Scheduling-Violation
Mitigation in Time-Sensitive Networking
Abstract
Time-Sensitive Networking (TSN) is designed to provide deterministic
performance for real-time systems, which usually have hard delay
requirements for Time-Triggered (TT) traffic. In order to guarantee
deterministic delays, TSN scheduling assigns specific time slots to TT
frames for their transmissions by TSN switches on their paths. However,
several factors may lead to scheduling violations, meaning that TT
frames are not sent as scheduled. Scheduling violations can cause the
increment of delays experienced by TT frames, which may breach their
delay requirements.
Existing TSN scheduling methods cannot deal with scheduling violations.
In our research, we propose TSN-Violation Mitigation (TSN-VM), which
dynamically reconfigures the schedule at each TSN switch distributedly
on a periodic basis, to mitigate the occurrence of scheduling
violations. TSN-VM is built upon our new real-time detection mechanism
to discover local violation information in each port of TSN switches.
TSN-VM is the first real-time algorithm that can deal with scheduling
violations in TSN. Its convergence conditions are demonstrated in the
paper. Using TSN-VM, we can reduce the number of lag violations by more
than 90.74$\%$ and decrease the average and median
delays by more than 95.57$\%$ in the simulated avionic
system and industrial Ethernet compared with systems without TSN-VM.