C Prados

TL;DR: The presented approach aims for a general purpose, fieldbus-like transmission system, which provides deterministic data and timing to around 1000 stations and automatically compensates for fiber lengths in the order of 10 km.

TL;DR: The paper discusses the current performance of WR hardware, along with present and foreseen applications, and describes current efforts to standardise WR under IEEE 1588 and recent developments on reliability of timely data distribution.

Abstract: White Rabbit (WR) is a time-deterministic, low-latency Ethernet-based network which enables transparent, subns accuracy timing distribution. It is being developed to replace the General Machine Timing (GMT) system currently used at CERN and will become the foundation for the control system of the Facility for Antiproton and Ion Research (FAIR) at GSI. High reliability is an important issue in WR’s design, since unavailability of the accelerator’s control system will directly translate into expensive downtime of the machine. A typical WR network is required to lose not more than a single message per year. Due to WR’s complexity, the translation of this real-world-requirement into a reliability-requirement constitutes an interesting issue on its own – a WR network is considered functional only if it provides all its services to all its clients at any time. This paper defines reliability in WR and describes how it was addressed by dividing it into sub-domains: deterministic packet delivery, data resilience, topology redundancy and clock resilience. The studies show that the Mean Time Between Failure (MTBF) of the WR Network is the main factor affecting its reliability. Therefore, probability calculations for different topologies were performed using the “Fault Tree analysis” and analytic estimations. Results of the study show that the requirements of WR are demanding. Design changes might be needed and further in-depth studies required, e.g. Monte Carlo simulations. Therefore, a direction for further investigations is proposed.

TL;DR: The WhiteRabbit timing network is a deterministic field bus, based on synchronous GBit Ethernet and the Precision Time Protocol (PTP).