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White Rabbit Standardization in IEEE1588 Precision Time Protocol

The White Rabbit (WR) extension of the IEEE1588-2008 standard has been generalized into a text of the 2019 edition of the IEEE1588 standard (IEEE1588-2019). The standardization process of WR finished with the publication of IEEE1588-2019 on 15 June 2020. The generalized White Rabbit (under the name High Accuracy) is the third default PTP Profile included in Annex I of the IEEE1588-2019, along with a number of optional features; see details of White Rabbit integration into IEEE1588-2019 as High Accuracy.

This wiki page documents the project of WR standardization that started in 2012 and finished in 2020. The goal of the project was to transform the White Rabbit extension of IEEE1588 into a recognized standard. The feasibility of the project goal, the target standard, the means and process of standardizing were all within the scope of this project.

White Rabbit Standardization Project

Introduction

White Rabbit (WR) is an extension of the IEEE1588-2008 (Precision Time Protocol, PTP) standard. The WR extension has been developed to synchronize nodes in a packet-based network with sub-ns accuracy. Achieving such high accuracy results from the combination of IEEE1588-2008 with the following further extensions:

  1. Clock syntonization over the physical layer (similar to SyncE),
  2. Enhancement of timestamps precision through phase detection,
  3. Automatic precise evaluation of link asymmetry.

White Rabbit evolved into an extension of the Precision Time Protocol (PTP) and is therefore referred to as WRPTP.
WRPTP is fully compatible with PTP and is defined as a PTP Profile.

White Rabbit Specification (WR Spec)

The White Rabbit Protocol is defined in the White Rabbit Specification (WR Spec) that describes:

  • Hardware requirements for implementing WRPTP,
  • Protocol requirements for WRPTP-compatibility.

White Rabbit Specification material

Standardization benefits and paths

Standardizing White Rabbit is unquestionably beneficial to the project and its users and brings a substantial boost to the number of WR applications.

Advantages of standardization:

  • Easier co-operation with companies,
  • Increase of stability, viability and credibility of the White Rabbit solution,
  • Feedback of experts that enables to polish the solution and make it more mature and robust.

Standardization is a considerably long process that can be approached in various ways and from various directions. Potential paths (see presentation) for WR's standardization had been identified as follows:

White Rabbit standardization within the IEEE1588 revision process

Including White Rabbit into the IEEE1588 (PTP) standard has been identified as the best and feasible WR standardization path.

White Rabbit was proposed to be included into PTP as a High Accuracy Option/Profile (presentation, document) at the Special Session of ISPCS2012. This Special Session showed an interest and need for reasonably broad IEEE1588 revision. The first step in revising PTP was the preparation of Project Authorization Request (PAR) by a Study Group at the beginning of 2013. The PAR states that the revised protocol "enhances support for synchronization to better than 1 nanosecond" which reflects the enthusiasm of the group to evaluate incorporation of the White Rabbit extensions into the standard.

The revision process of the IEEE1588 Precision Time Protocol (PTP) standard started in mid-2013. The revision work was performed by the P1588 Working Group, which consists of over 180 members from all over the world representing industry and science, including CERN. The Working Group was arranged in 5 sub-committees focusing on different aspects of the PTP revision, namely: Architecture, Management, Upkeep, Security and High Accuracy Enhancements. The High Accuracy sub-committee was lead by CERN representative. It was dedicated to generalizing White Rabbit solutions to a broader range of applications and include these generalized solutions in the IEEE1588 standard.

  • P1588 Working Group
  • High Accuracy P1588 Subcommittee: Co-chairs: John MacKay (Progeny Systems Corporation) and Maciej Lipinski (CERN). Sec/Editor: Geoff Garner (Consultant for Huawei Technologies Co., Ltd.)
  • IEEE1588-2008 standard, available through IEEE Explore Digital Library (payable)

Goal of this project

The goal of this project is to standardize the White Rabbit extension of the IEEE1588-2008 standard.

Project plan

  1. Evaluation of standardization path/method
    1. White Rabbit Standardization Group established to help in evaluation (the end of April 2012):
      • representatives of Scientific Institutes (e.g. CERN, GSI) and companies (e.g. NI)
      • members of WR Collaboration and external experts
      • the responsibility of the group is to perform the further actions
    2. Each potential path for WR standardization needs to be identified, studied and evaluated
    3. The most suitable path (in terms of costs, efforts, time) decided (the end of 2012)
  2. Standardization of White Rabbit
    1. The standardization effort (started in February 2013)
    2. Publication of a standard that includes White Rabbit marks the end of the project

Selected documents/presentations/links

Project's timeline

Task End date
1. Establishment of WR Standardization Group end of April 2012
2. Potential standardization path evaluation end of September 2012
3. Decision of standardization path choice end of 2012
4. Start of standardization efforts February 2013
5. First face-to-face IEEE1588 Study Group meeting, Washington April 2013
6. Project Authorization Request (PAR) submitted May 2013
7. Project Authorization Request (PAR) approved June 2013
8. P1588 Working Group formalized August 2013
9. High Accuracy Enhancements sub-committee created August 2013
10. P1588 Plenary meeting and ISPCS, Lemgo September 2013
11. P1588 Plenary meeting organized at CERN April 2014
12. P1588 Plenary meeting and ISPCS, Austin September 2014
13. P1588 Plenary meeting, San Francisco January 2015
14. P1588 Plenary meeting, Stockholm May 2015
15. P1588 Plenary meeting, Knoxville August 2015
16. P1588 Plenary meeting, Paso Robles January 2016
17. Standardization progress reported at WR Workshop (see) March 2016
18. P1588 Plenary meeting, Paris April 2016
19. P1588 Plenary meeting, Portsmouth October 2016
20. P1588 Plenary meeting, Austin January 2017
21. P1588 Internal Working Group Ballot 1 Jan to Oct 2017
22. P1588 Plenary meeting, Kista November 2017
23. P1588 Internal Working Group Ballot 2 Oct 2017 to Feb 2018
24. P1588 Internal Working Group Ballot 3 Feb to June 2018
25. Sponsor Ballot Pre-check Feb to Jun 2018
26. P1588 Sponsor Ballot 1 Jun to July 2018
27. The 2018 edition of ISPCS conference was hosted at CERN to celebrate near-completion of the new IEEE1588 revision Sept/Oct 2018
28. Standardization progress reported at WR Workshop (see) Oct 2018
29. P1588 Sponsor Ballot 1 re-circulation 1 Started in May 2019
30. P1588 Sponsor Ballot 1 re-circulation 2 Started in August 2019
31. P1588 Sponsor Ballot passed - Draft submitted to IEEE RevCom for approval September 2019
32. IEEE RevCom recommended the revised P1588 draft for approval to IEEE SASB (look for P1588) 6 November 2019
33. IEEE SA Standards Board (SASB) approved the revised P1588 draft (see the announcement) 7 November 2019
34 IEEE 1588-2019 supersedes IEEE 1588-2008 (https://standards.ieee.org/standard/1588-2019.html) 7 November 2019
35 Publication of the new IEEE1588-2019 with High Accuracy Profile/Options - WR standardization is completed 16 June 2020
36 The successful completion of WR Standardization makes the front CERN page with the article
"White Rabbit, a CERN-born technology, sets a new global standard"		 26 June 2020
37 Presentation at 11th WR Workshop (online): IEEE 1588-2019 High Accuracy Profile and more 6 October 2021

Maciej Lipinski - 11 October 2021