Meeting the real-time constraints with standard Ethernet in an in-vehicle network

Abstract

Vehicular networks have traditionally focused on the real-time delivery of critical control messages for safe car operation. Unfortunately, the real-time requirements often cripple the development of flexible car applications by tying the application network stack to underlying physical networks. While popular real-time vehicular networks guarantee the timely delivery of prioritized messages, they often lack in bandwidth and flexibility, which limits the range of car network applications. In this work, we explore the idea of replacing the current vehicular network with standard switched Ethernet, the most popular LAN technology in computer networks. Ethernet is attractive in providing high bandwidth at a low cost with easy and flexible configuration. The most challenging part is to guarantee the real-time delivery of mission-critical messages. We first show that the soft message delivery latency of 10s to 100s milliseconds can be easily met in 100 Mbps switched Ethernet despite coexistence of high-bandwidth network applications. For meeting the hard delivery latency on the order of 100 microseconds for critical control messages, we propose limiting the path MTU to the destination node with priority queuing from IEEE 802.1Q. Our simulation shows that we can satisfy 100 microseconds of latency even in a rich set of vehicular applications without any modification of the application network stack.