1,434 research outputs found
10 Gigabit White Rabbit: sub-nanosecond timing and data distribution
Time synchronization is a critical feature for many scientific facilities and industrial
infrastructures. The required performance is progressively increasing everyday, for instance, few tens of
nanoseconds for Fifth Generation (5G) networks or sub-nanosecond accuracy on next family of particle
accelerators and astrophysics telescopes. Due to this exigent accuracy, many applications require specific
timing dedicated networks, increasing the system cost and complexity. Under this context, the new IEEE
1588-2019 High Accuracy (HA) default profile is intensively based on White Rabbit (WR) which can
provide sub-nanosecond accurate synchronization for Ethernet networks. However, current WR solutions
have not been designed to work properly with high data bandwidth delivery services even in 1 Gigabit
Ethernet (GbE) links. On this contribution, the authors propose a new architecture design that enables WR
and, consequently, the IEEE 1588-2019 HA profile to be deployed over 10 GbE links solving the already
identified data bandwidth problem. Furthermore, this work addresses different experiments needed to
characterize the system performance in terms of time synchronization and data transfer. As final result, this
contribution presents for the first time in the literature a new WR system which allows high bandwidth data
exchange in 10 GbE networks while providing sub-nanosecond accuracy synchronization. The proposed
solution maintains the time synchronization performance of existing WR 1 GbE devices with significant
advantages in terms of latency and data bandwidth, enabling its deployment in applications that integrate
data and synchronization information in the same network.European Union (EU)
725490H2020 ASTERICS
653477AMIGA7
RTI2018-096228-B-C3
Precise Network Time Monitoring: Picosecond-level packet timestamping for Fintech networks
Network visibility and monitoring are critical in modern networks due to the increased density, additional complexity, higher bandwidth, and lower latency requirements. Precise packet timestamping and synchronization are essential to temporally correlate captured information in different datacenter locations. This is key for visibility, event ordering and latency measurements in segments as telecom, power grids and electronic trading in finance, where order execution and reduced latency are critical for successful business outcomes. This contribution presents Precise Network Time Monitoring (PNTM), a novel mechanism for asynchronous Ethernet packet timestamping which adapts a Digital Dual Mixer Time Difference (DDMTD) implemented in an FPGA. Picosecond-precision packet timestamping is outlined for 1 Gigabit Ethernet. Furthermore, this approach is combined with the White Rabbit (WR) synchronization protocol, used as reference for the IEEE 1588-2019 High Accuracy Profile to provide unprecedented packet capturing correlation accuracy in distributed network scenarios thanks to its sub-nanosecond time transfer. The paper presents different application examples, describes the method of implementation, integration of WR with PNTM and subsequently describes experiments to demonstrate that PNTM is a suitable picosecond-level distributed packet timestamping solutionNational project AMIGA7
RTI2018-096228-B-C32Andalusian project SINPA
B-TIC-445-UGR1
Global Time Distribution via Satellite-Based Sources of Entangled Photons
We propose a satellite-based scheme to perform clock synchronization between
ground stations spread across the globe using quantum resources. We refer to
this as a quantum clock synchronization (QCS) network. Through detailed
numerical simulations, we assess the feasibility and capabilities of a
near-term implementation of this scheme. We consider a small constellation of
nanosatellites equipped only with modest resources. These include quantum
devices such as spontaneous parametric down conversion (SPDC) sources,
avalanche photo-detectors (APDs), and moderately stable on-board clocks such as
chip scale atomic clocks (CSACs). In our simulations, the various performance
parameters describing the hardware have been chosen such that they are either
already commercially available, or require only moderate advances. We conclude
that with such a scheme establishing a global network of ground based clocks
synchronized to sub-nanosecond level (up to a few picoseconds) of precision,
would be feasible. Such QCS satellite constellations would form the
infrastructure for a future quantum network, able to serve as a globally
accessible entanglement resource. At the same time, our clock synchronization
protocol, provides the sub-nanosecond level synchronization required for many
quantum networking protocols, and thus, can be seen as adding an extra layer of
utility to quantum technologies in the space domain designed for other
purposes.Comment: 20 pages, 12 figures and 6 tables. Comments are welcom
IEEE 1588 High Accuracy Default Profile: Applications and Challenges
Highly accurate synchronization has become a major requirement because of the rise of
distributed applications, regulatory requests and position, navigation and timing backup needs. This fact
has led to the development of new technologies which fulfill the new requirements in terms of accuracy
and dependability. Nevertheless, some of these novel proposals have lacked determinism, robustness,
interoperability, deployability, scalability or management tools preventing them to be extensively used in real
industrial scenarios. Different segments require accurate timing information over a large number of nodes.
Due to the high availability and low price of global satellite-based time references, many critical distributed
facilities depend on them. However, the vulnerability to jamming or spoofing represents a well-known
threat and back-up systems need to be deployed to mitigate it. The recently approved draft standard IEEE
1588-2019 includes the High Accuracy Default Precision Time Protocol Profile which is intensively based on
the White Rabbit protocol. White Rabbit is an extension of current IEEE 1588-2008 network synchronization
protocol for sub-nanosecond synchronization. This approach has been validated and intensively used
during the last years. This paper revises the pre-standard protocol to expose the challenges that the High
Accuracy profile will find after its release and covers existing applications, promising deployments and
the technological roadmap, providing hints and an overview of features to be studied. The authors review
different issues that have prevented the industrial adoption of White Rabbit in the past and introduce the
latest developments that will facilitate the next IEEE 1588 High Accuracy extensive adoption.This work was supported in part by the AMIGA6 under Grant AYA2015-65973-C3-2-R, in part by the AMIGA7 under Grant
RTI2018-096228-B-C32, and in part by the Torres Quevedo under Grant PTQ2018-010198
Time transfer techniques: Historical overview, current practices and future capabilities
A brief historical review of time transfer techniques used during the last twenty years is presented. Methods currently used are discussed in terms of cost effectiveness as a function of accuracy achievable. Future trends are also discussed in terms of projected timekeeping capabilities
A Survey of Clock Synchronization Over Packet-Switched Networks
Clock synchronization is a prerequisite for the realization of emerging applications in various domains such as industrial automation and the intelligent power grid. This paper surveys the standardized protocols and technologies for providing synchronization of devices connected by packet-switched networks. A review of synchronization impairments and the state-of-the-art mechanisms to improve the synchronization accuracy is then presented. Providing microsecond to sub-microsecond synchronization accuracy under the presence of asymmetric delays in a cost-effective manner is a challenging problem, and still an open issue in many application scenarios. Further, security is of significant importance for systems where timing is critical. The security threats and solutions to protect exchanged synchronization messages are also discussed
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