Experiences with EtheReal: a fault-tolerant real-time Ethernet switch

We present our experiences with the implementation of a real-time Ethernet switch called EtheReal. EtheReal provides three innovations for real-time traffic over switched Ethernet networks. First, EtheReal delivers connection oriented hard bandwidth guarantees without requiring any changes to the end host operating system and network hardware/software. For ease of deployment by commercial vendors, EtheReal is implemented in software over Ethernet switches, with no special hardware requirements. QoS support is contained within two modules, switches and end-host user level libraries that expose a socket like API to real time applications. Secondly, EtheReal provides automatic fault detection and recovery mechanisms that operate within the constraints of a real-time network. Finally EtheReal supports server-side push applications with a guaranteed bandwidth link-layer multicast scheme. Performance results from the implementation show that EtheReal switches deliver bandwidth guarantees to real time-applications within 0.6% of the contracted value, even in the presence of interfering best-effort traffic between the same pair of communicating hosts.