Advanced Modeling and Analysis of Individual and Combined TSN Shapers in OMNeT++

The selection of a Time-Sensitive Networking (TSN) shaping mechanism is a crucial design decision that impacts the Quality of Service (QoS) of applications and configuration complexity. However, current research has mainly evaluated TSN shapers individually, despite them being designed to work together in an egress port. Hence, the lack of investigation of the mixed TSN shaping mechanism is a major limitation of the current state of the art. Combined TSN traffic shaping provides greater flexibility to improve QoS than individual shapers, making it particularly beneficial for real-time applications. This paper aims to bridge this research gap by implementing the Asynchronous Traffic Shaper (ATS) in a plug-and-play manner, enabling its use individually or in combination with other TSN shapers. We propose various models of mixed TSN shaper architectures and implement the frozen and non-frozen credit behavior of the Time Aware Shaper (TAS) + Credit Based Shaper (CBS) during the guard band (GB) using OMNeT++. Furthermore, we compare the simulation results of ATS and CBS with the Network Calculus (NC) upper bounds. Our results indicate that the simulated delays (SMDs) were significantly lower than the theoretical worst-case delays (WCDs) obtained from the NC, indicating the need for tighter theoretical upper bounds, particularly for higher network loads. To the best of our knowledge, we are the first to provide simulation-based performance analysis of the combined
$\text{TAS}+\text{ATS}+\text{CBS}$
and
$\text{TAS}+\text{ATS}+\text{Strict}$
Priority (SP) architecture. Overall, this paper highlights the benefits of combining TSN shapers and encourages further research into the potential advantages of utilizing multiple shapers simultaneously to decrease reliance on TAS and CBS.