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 requirements: precise knowledge 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), therefore it is referred to as WRPTP. WRPTP is fully compatible with PTP and is currently defined as a PTP Profile.
White Rabbit Specification (WR Spec)
White Rabbit Protocol is defined in the White Rabbit Specification (WR Spec) which describes:
- hardware requirements which need to be fulfilled to implement WRPTP
- protocol requirements which need to be fulfilled to be WRPTP-compatible
White Rabbit Specification* materials:
- the latest version of the WR Spec
- older versions of the WR Spec (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
- sources (Latex) of the WR Spec document
White Rabbit Standardization
Standardizing White Rabbit is unquestionably beneficial to the project
and is expected to bring substantial boost to the number of WR's
applications.
Advantages of standardization:
- easier co-operation with companies
- increase of stability, viability and credibility of the White Rabbit solution (favored by potential users)
- feedback of field's expert which enables to polish the solution and make it more mature
Standardization is a considerably long process which 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
- Standard within other standardization body/consortium
White Rabbit standardization within IEEE1588 revision
Including White Rabbit into 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 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 is to include White Rabbit into PTPv3. This
is proposed to be done as a set of High Accuracy options and profile --
a detailed proposal can be found
here .
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 White Rabbit Protocol.
Project's plan
- _White Rabbit Standardization Group_ is to be
established (by 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) should be decided (by the end of 2012)
- The standardization effort should be started
- An official White Rabbit standard 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. | White Rabbit standardization | depends on path choice |