IEEE 1588 High Accuracy Default Profile: Applications and Challenges

Abstract

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 backup 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. INDEX TERMS GPS backup, high accuracy profile, IEEE 1588, time dissemination, precision time protocol, PTP, white rabbit.

Testbed Evaluation of Distributed Radio Timing Alignment Over Ethernet Fronthaul Networks

“…Section IV-B). Hence, the BBU considers a delay measurement uncertainty of γ = 20 ns (PPS RTC's maximum time offset) when computing (11).…”

“…Instead, timing references are expected to be distributed by the typical combination of global navigation satellite system (GNSS) disciplined clocks, the IEEE 1588 precision time protocol (PTP) [9] and Synchronous Ethernet [10]. As of today, with the recently approved IEEE 1588-2019 draft standard featuring the High Accuracy profile for sub-nanosecond accuracy [11], and with ongoing efforts from the Question 13 group of ITU-T study group 15, such as the enhanced synchronous Ethernet Equipment Clock (eEEC) [12], this combination remains the state-of-the-art.…”

Clock Synchronization Algorithms Over PTP-Unaware Networks: Reproducible Comparison Using an FPGA Testbed

“…9 present similar shapes, the difference between the average m-to-s and s-to-m delays varies in each hop configuration. This difference refers to the static delay asymmetry component modeled in (10), which varies per hop because each port of the PTP-unaware switch introduces different static hardware latencies (e.g., Ethernet PHY latencies). For example, note that the asymmetries observed with the XO and OCXO match closely on each hop configuration (using the same ports).…”

“…PTP has achieved widespread usage primarily since its 2008 revision, with the so-called PTPv2 [8]. It is continuously evolving and recently consolidated the IEEE 1588-2019 standard revision [9], which features, for example, the so-called High Accuracy profile for sub-nanosecond accuracy [10].…”

10 Gigabit White Rabbit: Sub-Nanosecond Timing and Data Distribution

“…WR includes some extensions for IEEE 1588-2008 that have been accepted in a draft to take part in IEEE 1588-2019 as High Accuracy (HA) profile [38], [39]. The WR specification describes that this technology provides sub-nanosecond accuracy and frequency distribution precision better than 50 picoseconds for point-to-point links up to 10 km.…”