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
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
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 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:
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
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
for WR's standardization had been identified as follows:
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
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.