White Rabbit Protocol (WRPTP)
White Rabbit* (WR) is a protocol developed to synchronize nodes in a packet-based network with sub-ns accuracy. The protocol results from the combination of IEEE1588-2008 (Precision Time Protocol, PTP) with two further extensions: automatic precise measurement of the link delay and clock syntonization over the physical layer with Synchronous Ethernet (SyncE).
White Rabbit evolved into an extension of Precision Time Protocol (PTP) and is therefore referred to as WRPTP. WRPTP is fully compatible with PTP and is currently 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:
- WR Specifications
- WR Specification - latest version
- older versions of the WR Spec (to show how the WR Spec evolved)
- sources (Latex) of the WR Spec document
- short information regarding different versions (i.e. feedback, comments, diffs)
- issues and possible improvements to the current version
White Rabbit Standardization
Standardizing White Rabbit is unquestionably beneficial to the project 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 have been identified. These include:
-
Standardization at 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 Institute of Electrical and Electronics
Engineers (IEEE)
- as a PTP Profile
- included into version 3 of PTP (PTPv3)
- 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.
The Special Session showed an interest and need for reasonably broad IEEE1588 revision. The first step in revising PTP is the preparation of Project Authorization Request by a Study Group. The Call For Participation in the Study Group has been announced in January 2013 inviting everyone to join the works.
White Rabbit will be represented in the IEEE1588 revision process by
CERN with a clear objective to include the White Rabbit features into
PTPv3. This is proposed to be done as a set of High Accuracy options and
profile and "a detailed
proposal"":/uploads/334c98271a16ac6da5d02eab01104e10/HighAccuracy.v0.2.pdf has been made.
Support of the initiative by different parties is highly encouraged --
everyone can do so by participating in revision works.
Goal of this project
The ultimate goal of this project is to standardize the White Rabbit Protocol.
Project plan
- _White Rabbit Standardization Group_ established (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)
- The standardization effort started (February 2013)
- An official standardization of White Rabbit will mark the end of the project
Project's timeline
Task | Expected end time | |
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 | Feb 2013 |
5. | First face-to-face IEEE1588 Study Group meeting | April 2013 |
6. | Project Authorization Request (PAR) submitted | second half of 2013 |
7. | Preparation of IEEE1588 revision by the Working Group | 2013,2014,... |
4. | New revision of IEEE1588 with WR published | not later then 2018 |
Maciej Lipinski, 7 February 2013