Performance Bounds in Switched Ethernet Onboard Networks

In modern automotive and aeronautic onboard networks, a driving force exists to integrate multiple communication networks onto a single switched Ethernet network. Goals for future onboard communication networks are low weight, low price, high bandwidth, and certifiable safety. Certainly, these objectives influence each other and are difficult to fulfill. Furthermore, an existing certification may not encourage an expensive recertification of novel communication technologies. Aircraft cabin networks are subject to certification, as they not only cover comfort functions such as In-Flight Entertainment, but also safety related functions such as the announcement of evacuation messages or the polling of smoke detectors. This work addresses the applicability of a switched queuing network for both safety relevant and comfort functions in aircraft cabin networks. Hard performance guarantees on latency and jitter must be fulfilled. The state-of-the-art approach to determine worst case bounds in queuing networks is NetworkCalculus. The tightness ofNetwork Calculus is subject to ongoing research. Recent work even showed the NP-hardness of determining tight bounds in general networks. In this work, we propose a packetized model based on a mixed-integer program, which is able to express the worst-case in a closed-form representation. The proposed algorithm allows better mapping of packetized switched networks compared to known state-of-the-art Network Calculus approaches. The presented approach is embedded in the performance evaluation platform DIMTOOL. This platform provides several performance evaluation techniques, such as network simulation and Network Calculus, in one single toolbox. Having a consistent view on performance bounds allows for a rapid evaluation of the worst case bounds of the cabin network, which in turn is required for the certification process. We show that the hard performance bounds are guaranteed, which opens the investigated switched queuing network for a wide range of applications.