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Tictoc Status Pages

Timing over IP Connection and Transfer of Clock (Concluded WG)
Int Area: Éric Vyncke, Erik Kline | 2008-Mar-11 —  

2021-08-17 charter

Timing over IP Connection and Transfer of Clock (tictoc)


 Current Status: Active

     Karen O'Donoghue <odonoghue@isoc.org>
     Yaakov (J) Stein <yaakovjstein@gmail.com>

 Internet Area Directors:
     Erik Kline <ek.ietf@gmail.com>
     Éric Vyncke <evyncke@cisco.com>

 Internet Area Advisor:
     Erik Kline <ek.ietf@gmail.com>

 Mailing Lists:
     General Discussion: tictoc@ietf.org
     To Subscribe:       https://www.ietf.org/mailman/listinfo/tictoc
     Archive:            https://mailarchive.ietf.org/arch/browse/tictoc/

Description of Working Group:

    The Timing over IP Connections and Transfer Of Clock (TICTOC) WG is
    concerned with highly accurate time and frequency distribution over
    native IP and MPLS-enabled IP Packet Switched Networks (PSNs). While
    this need arises from a variety of sources (see
    draft-bryant-tictoc-probstat-01.txt), the application areas of focus for
    this WG are:

    (1) Network infrastructures with the need for highly accurate time and
    frequency distribution within well-engineered service provider or
    enterprise campus networks. On-path support with specialized hardware
    may be expected to be available at one or more hops on a given path.

    (2) Individual hosts and devices on the public Internet requiring
    functionality or performance not currently available in NTP. On-path
    support may be utilized if available, but is not expected. This
    application brings additional requirements beyond improved accuracy, for
    example, the traceable and authenticated distribution of UTC time,
    including correct handling of leap seconds.

    The NTP Working Group is currently standardizing the fourth version of
    NTP for time distribution over IP networks. The NTP WG has focused its
    deliverables largely on standardizing the currently deployed NTPv4,
    while collecting requirements for future extensions. These requirements
    will transition to the tictoc WG for further development. Meeting those
    requirements may include revision of the protocol to a new version
    level. However, in all cases backwards compatibility and coexistence
    with currently deployed NTPv4 is a paramount concern. An applicability
    statement will describe the use cases for which any extension of NTP is

    The IEEE Test and Measurement Society is in the closing stages of
    standardizing a second version of IEEE1588. This is unofficially known
    as IEEE1588v2 and is expected to be published as IEEE1588-2008.
    IEEE1588v2 is emerging as a viable solution for time transfer over
    service provider and campus Ethernet networks, and for which on-path
    hardware support is becoming available. IEEE1588v2 specifically
    encourages other standards organizations to adapt it to their
    requirements, and provides guidelines for doing so. TICTOC will
    determine whether a profile for IEEE1588v2 over IP or MPLS-enabled IP
    networks would be suitable for (1), and if so will produce a profile
    within the guidelines provided in the IEEE1588v2 specification. An
    applicability statement will describe the use cases for which any
    profile of IEEE1588v2 is targeted.

    Time and Frequency distribution is considered by many to be a complex
    and often esoteric subject area. The WG will develop a modular framework
    in order to map out components within the solution space, define
    terminology, and identify common areas of protocol work that can be
    capitalized upon.

    TICTOC will also consider the co-existence of IEEE1588v2 and NTP in the
    same network. In doing so, TICTOC will first verify that the data model
    of NTP can be accommodated by IEEE1588v2 protocol operation and document
    any deficiencies compared to NTP. If there is a need to map the data
    models, it will produce a specification for how to utilize IEEE 1588 in
    a localized region as one portion of an NTP-based system.

    TICTOC protocols will be applicable to a variety of link layer
    technologies. To get the highest quality time and frequency transfer the
    user should take advantage of two types of on-path service where they
    are available: Link based frequency transfer, and hop-by-hop delay
    correction (for time).  Examples of link based frequency support are
    SONET/SDH, TDM, Synchronous Ethernet and DSL with timing reference
    support. The main types of support that can be provided by a network
    element are boundary clock (where the clock is regenerated at the node
    in a multistage master slave relationship) and transparent clock where
    corrections are applied to time transfer packets as they pass through to
    compensate for the queuing delay, and where known for asymmetry in the
    link delay.  Transparent clock  (queue delay correction) requires
    routers to identify a time transfer packet, record the queuing delay,
    and either apply an on the fly correction to the packet, or to generate
    a follow-up packet with the necessary time correction information.
    TICTOC will ensure that any transparent clock design is acceptable in an
    Internet environment. On-path support is not a given, and TICTOC will
    investigate methods for automatically discovering when this support is
    available and when it is not.

    TICTOC will transfer time and frequency over both IP and IP enabled MPLS
    PSNs.  One of the major users of TICTOC technology is the service
    provider community, where MPLS enabled IP networks are common. If
    necessary, TICTOC may take advantage of the path control properties of
    MPLS and the ability to signal modifications to per packet forwarding

    The security of time transfer, including the authentication of the time
    reference is an important consideration and must be designed in from the

    The ultimate system-level accuracy of time and frequency transfer
    depends on a number of factors outside the scope of the protocols
    themselves. Thus, even if it is possible for TICTOC to make a number of
    improvements at the protocol level to facilitate more accurate time and
    frequency transfer, it is impossible for the WG to provide system-level
    accuracy guarantees on its own.

    The TICTOC WG will co-ordinate with the PWE3 and NTP WGs in the IETF, as
    well as IEEE1588, IEEE 802.1AS and ITU-T SG15 Q13. It is also expected
    that active individuals in the TICTOC WG will propose the formation of
    an IRTF RG to study more advanced aspects of time and frequency

    First phase Objectives:

    - To develop a time and frequency distribution requirements document for
    the two cases listed above, including coexistence of the two as appropriate.

    - To develop a document defining the modular breakdown of functionality
    within the solution space.

    - To determine the extent to which these requirements can be satisfied
    using IEEE1588v2 and NTPv4 within each use case, along with an
    associated gap analysis for what requirements are not met without
    adaptation or extension of these protocols.

    - To develop an IEEE1588v2 profile as necessary for time and frequency
    distribution, with primary focus on (1). This profile will include a MIB
    module for IEEE1588v2.

    - To develop extensions to NTPv4 as necessary for time and frequency
    distribution, with primary focus on (2).

    - If required, to develop mechanisms for coexistence of IEEE1588v2 and NTP.

    - To document threat analyses and security mechanisms for all protocols
    developed by the WG.

    - To document media mappings for link layer technologies of interest.

    Second phase Objectives (requiring re-charter of the WG):

    To propose and document algorithms, protocols and mechanisms for
    transport, frequency acquisition, ranging, and packet selection/discard,
    master clock selection, path selection, OAM, synchronization status
    messaging, performance monitoring, security, and network management.

Goals and Milestones:
  Mar 2016 - 1588v2 profile, if needed, document exits WGLC
  Apr 2016 - MIB for IEEE 1588v2 profile and NTPv4 extensions (TICTOC MIB) document exits WGLC
  May 2016 - Prioritize second phase deliverables and add milestones or re-charter document exits WGLC
  Jun 2016 - IEEE 1588v2 YANG Model exits WGLC
  Jun 2016 - Publish Experimental RFC on multi-path time synchronization
  Jul 2016 - Publish Experimental RFC on transporting time over MPLS
  Done     - Security document(s) document exits WGLC

All charter page changes, including changes to draft-list, rfc-list and milestones:

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