Sub-nanosecond synchronization accuracy for time-sensitive applications on industrial networks

Abstract

White Rabbit (WR) is a technology born at CERN able to provide sub-nanosecond accuracy for time and frequency transfer using standard PTP and Synchronous Ethernet (SyncE). WR was designed to be the main time provider system for scientific infrastructures such as particle accelerators and colliders. This contribution proposes a change of approach for the WR PTP distribution to become a timing solution with strong focus on engineering frameworks, such as Smart Grid. This approach includes a new design following IEC 61850, where new developments make possible for WR devices to work as Transparent Clocks (TCs) instead of Boundary clocks (BCs) as in the case today. This maximizes the interoperability with other industrial devices and, at the same time, the utilization of TCs offers better synchronization results since PTP messages include the entire network delay considering all TCs as a unique fiber. Using TCs for time and data propagation also opens the doors to high-availability and fault tolerance features for mission-critical and time-sensitive applications. It supports the development of redundancy protocols, such as HSR or PRP to guarantee the delivery and reception of critical services such as timing and substation events (GOOSE, GSSE, SMV). Finally, P2P approach offers a better synchronization mechanism to avoid synchronization loss of middle nodes and also supports the development of redundancy protocols to make possible the migration of WR to industrial networks.

Enhancing White Rabbit Synchronization Stability and Scalability Using P2P Transparent and Hybrid Clocks

“…This involves the development of two new types of P2P WR clocks: Transparent (TC) and Hybrid (HY) clocks based on the current software stack implementation of PPSi using a Portable Operating System Interface (POSIX) implementation, in contrast to previous ones (no-POSIX) [24], thus facilitating the integration of these features in current WR devices. Moreover, this article includes a longer deployment experiment and results in comparison to [24], [25], deploying daisychains cascades composed of up to 19 nodes. Next Section III focuses on these developments and the results obtained, being significantly better than the results of the default E2E WR implementation.…”

A Fully Programmable White-Rabbit Node for the SKA Telescope PPS Distribution System

“…In addition to the conventional tree topology of the timing networks, new network topologies are currently under study in WR to add some mechanisms to improve fault tolerance and security. Examples of this paper are in [33] and [34] which incorporate transparent clocks and redundancy protocols into the WR technology such as high-availability seamless redundancy to ensure data delivery and reception in critical applications such as control network, real-time applications, or smart grids.…”