Ethernet-based timing system for accelerator facilities: The IFMIF-DONES case
Metadatos
Afficher la notice complèteEditorial
Elsevier
Materia
IFMIF-DONES Network synchronization Timing system IEEE 1588 Network time protocol
Date
2023-06-20Referencia bibliográfica
C. Megías et al. Ethernet-based timing system for accelerator facilities: The IFMIF-DONES case. Computer Networks 233 (2023) 109897[https://doi.org/10.1016/j.comnet.2023.109897]
Résumé
This article presents the design of a timing system for accelerator facilities, which relies on a general networking
approach based on standard Ethernet protocols that keeps all the devices synchronized to a common time
reference. The case of the IFMIF-DONES infrastructure is studied in detail, providing a framework for the
implementation of the timing system. The network time protocol (NTP) with software timestamping and the
precision time protocol (PTP) with hardware timestamping are used to synchronize devices with sub-millisecond
and sub-microsecond accuracy requirements, respectively. The design also considers the utilization of IEEE 1588
high accuracy default PTP profile (PTP-HA) to provide sub-nanosecond accuracy for the most demanding
components. Three different solutions for the design of the timing system are discussed in detail. The first solution
considers the deployment of one time-dedicated network for each synchronization protocol, while the
second one proposes the integration of the synchronization data of NTP and PTP into the networks of the facility.
The third solution relies on the single distribution of PTP-HA to all the systems. The final design aims to be fully
based on standard technologies and to be cost-efficient, seeking for interoperability and scalability, and minimizing
the impact on other systems in the facility. An experimental setup has been implemented to evaluate and
discuss the suitability of the solutions for the timing system by studying the synchronization accuracy obtained
with NTP, PTP and PTP-HA under different network conditions. It includes a timing evaluation platform that
tries to resemble the network architecture foreseen in the facility. The measured results revealed that PTP is the
most limiting protocol for the second solution. Using the default PTP configuration, it tolerates less than 20% of
maximum bandwidth utilization for symmetric bidirectional flows, and around 30% in the case of unidirectional
flows (server to client or client to server), with the current setup and using switches without enabled timing
support. This case study provides a better understanding of the trade-off between bandwidth utilization, synchronization
accuracy and cost in these kinds of facilities.