White rabbit precision time protocol on long-distance fiber links

Erik F. Dierikx, Anders E. Wallin, Thomas Fordell, Jani Myyry, Petri Koponen, Mikko Merimaa, Tjeerd J. Pinkert, Jeroen C.J. Koelemeij, Henk Z. Peek, Rob Smets

    Research output: Contribution to journalArticleScientificpeer-review

    113 Citations (Scopus)


    The application of White Rabbit precision time protocol (WR-PTP) in long-distance optical fiber links has been investigated. WR-PTP is an implementation of PTP in synchronous Ethernet optical fiber networks, originally intended for synchronization of equipment within a range of 10 km. This paper discusses the results and limitations of two implementations of WR-PTP in the existing communication fiber networks. A 950-km WR-PTP link was realized using unidirectional paths in a fiber pair between Espoo and Kajaani, Finland. The time transfer on this link was compared (after initial calibration) against a clock comparison by GPS precise point positioning (PPP). The agreement between the two methods remained within ±2 ns over three months of measurements. Another WR-PTP implementation was realized between Delft and Amsterdam, the Netherlands, by cascading two links of 137 km each. In this case, the WR links were realized as bidirectional paths in single fibers. The measured time offset between the starting and end points of the link was within 5 ns with an uncertainty of 8 ns, mainly due to the estimated delay asymmetry caused by chromatic dispersion.

    Original languageEnglish
    Article number7383303
    Pages (from-to)945-952
    Number of pages8
    JournalIEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
    Issue number7
    Publication statusPublished - 1 Jul 2016
    MoE publication typeA1 Journal article-refereed


    • Clocks
    • optical fiber networks
    • precision time protocol (PTP)
    • time dissemination
    • timing
    • White Rabbit


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