Determining a tight worst-case delay of switched Ethernet network in IEC 61850 architectures

Théo Docquier (1, 2, 3) , Ye-Qiong Song (1, 2) , Vincent Chevrier (1, 2) , Ludovic Pontnau (3) , Abdelaziz Ahmed-Nacer (3)

1 LORIA - Laboratoire Lorrain de Recherche en Informatique et ses Applications
2 SIMBIOT - SIMulating and Building IOT
3 SCLE-SFE

IEC 61850 has become the reference standard for Substation Automation Systems (SAS) in smart power grids. Switched Ethernet is used for machine to machine communication within SAS. In order to meet stringent real-time constraints, the IEC 61850 application layer protocols can be mapped into different IEEE802.1Q priorities according to their real-time constraints and application criticality. However, the delay evaluation to guarantee real-time requirements can be difficult to perform, especially for lower priority but still real-time constrained traffic. In fact, most existing end-to-end worst-case delay analyses provide upper-bounds, leading to some pessimism and consequently network resource over-provision. In this paper, we present a new method for determining a tight worst-case delay. This method is based on the study of flow characteristics from a given network path. As a flow is interfered by other concurrent flows on its path, their relative offsets with the considered flow greatly impact on its delay. Studying all combinations to find the actual worst-case delay results in high complexity. We show that this complexity can be reduced by only analysing local worst-case delay at each switch in stead of the whole path where the change at each switch would need re-analysing the already analysed switches. An algorithm is also proposed to perform the analysis. An illustrating example shows that our method can reduce the pessimism as it provides the tight worst-case delay instead of the upper-bound of the worst-case delay.

Mots clés: Index Terms-switched Ethernet; worst-case delay analy- sis; real-time; Strict-Priority; IEC 61850; smart grid

Domaines: Réseaux et télécommunications [cs.NI]

Théo Docquier, Ye-Qiong Song, Vincent Chevrier, Ludovic Pontnau, Abdelaziz Ahmed-Nacer. Determining a tight worst-case delay of switched Ethernet network in IEC 61850 architectures. 45th IEEE Conference on Local Computer Networks (LCN), Nov 2020, Sydney, Australia. ⟨hal-02971311⟩