WCTT analysis of avionics Switched Ethernet Network with WRR Scheduling

Abstract

Nowadays, a real-time embedded system often has to cope with flows with different criticality levels. Such a situation is forecasted for next generation avionics networks, in order to better use communication resources. Indeed, the present situation, where the Avionics Full Duplex switched Ethernet (AFDX) network is reserved for critical avionics flows, leads to a very lightly loaded network. Quality of Service (QoS) mechanisms such as service disciplines are mandatory in order to cope with the heterogeneous constraints of the different kinds of flows. Weighted Round Robin (WRR) is envisioned in the context of avionics. Worst-case traversal time (WCTT) analysis is mandatory to ensure that temporal constraints of flows are met. Network Calculus (NC) is a popular solution for this analysis and results exist for WRR. They lead to pessimistic upper bounds. The main contribution of this paper is to show how existing NC results for WRR can be applied and improved in the context of an avionics configuration. The resulting analysis is evaluated on an industrial size configuration.