White Rabbit Standardization in IEEE1588-2008
The White Rabbit extension of the IEEE1588-2008 standard is being
generalized into a text of the upcoming release of the standard. This
process is now in the final stage and it is due to finish around 2018,
publication of the standard in 2019. Once finished, the generalized
White Rabbit (under the name High Accuracy) will be the third default
PTP Profile included in Annex J of the IEEE1588.
This wiki page provides details regarding the White Rabbit extension and
its standardization in IEEE1588.
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 (Precision Time Protocol, PTP) with the following further extensions:
- clock syntonization over the physical layer (similar to SyncE),
- enhancement of timestamps precision through phase detection,
- 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 currently being defined as a
PTP Profile.*
The solutions in WRPTP are now being included by the P1588 Working Group in the next revision of the PTP standard.
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
- WR Specifications
- WR Specification - latest version
- older versions of the WR Specification (to show how the WR Spec evolved)
- short information regarding different versions (i.e. feedback, comments, diffs)
- issues and possible improvements to the current version
Standardization benefits and paths
Standardizing White Rabbit is unquestionably beneficial to the project and its users and is expected to bring 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
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. These included:
-
Standardization at the International Telecommunication Union-
Telecommunication Standardization Sector
(ITU-T)
- within Telecom Profile (G.827x) - currently being developed
- as a separate Profile (similar to Telecom)
-
Standardization at the Institute of Electrical and Electronics
Engineers (IEEE)
- as an IEEE1588 PTP Profile
- included into version 3 of PTP (PTPv3) (this is the chosen way of WR standardization)
- as a part of AVB Gen2, included in updated 802.1AS
- Standardization within another standardization body/consortium
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 White Rabbit extensions.
The revision process of the IEEE1588 Precision Time Protocol (PTP) standard started in mid-2013. The revision work is done 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 is 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 is lead by CERN representative. It is dedicated to generalizing White Rabbit solutions to a broader range of applications and including these generalized solutions in the IEEE1588 standard.
-
P1588 Working
Group
- P1588 Subcommittee High Accuracy: 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)
- The draft upcoming standard is not available to people outside the Working Group.
- What’s coming In the Next Edition of IEEE 1588?, Douglas Arnold, Sept 2017
Goal of this project
The goal of this project is to standardize the White Rabbit Protocol.
Project plan
- Evaluation of standardization path/method
- _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
- Each potential path for WR standardization needs to be identified, studied and evaluated
- The most suitable path (in terms of costs, efforts, time) decided (the end of 2012)
- _White Rabbit Standardization Group_ established
to help in evaluation (the end of April 2012):
- Standardization of White Rabbit within
P1588
- The standardization effort started (February 2013)
- An official standardization of White Rabbit will mark the end of the project
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 ballot for submission to sponsor ballot | October 2017 |
| 22. | P1588 Plenary meeting, Kista | November 2017 |
| xx. | ... standardizing ... | ... |
| --. | The 2018 edition of ISPCS conference will be held at CERN. If all goes well, during this conference, we will celebrate the finalization of the new revision of IEEE1588 and see first implementations | Sept/Oct 2018 |
| --. | Publication of the new revision of IEEE1588 with High Accuracy Option/Profile | 2019 |
Maciej Lipinski - 5 June 2018