White Rabbit Safran

# Case Studies

White Rabbit - Survey Mode

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Context and technical introduction

The Survey Mode feature was born out of the need to monitor the status of network nodes and the links between them. This is especially relevant in redundant time and frequency distribution topologies, which have a considerable number of optical links connected between nodes, needing constant supervision and statistical analysis over the operational time to ensure the correct behavior and guarantee the expected performance of the whole network.

Ideally, thinking about time and frequency dissemination networks, active and backup links should always offer satisfactory performance to ensure continuous operation in all the different scenarios. So, regarding the White-Rabbit technology, a main goal has been the development of a tool that allows measuring the quality of the link, even in links which are not used for time distribution but for monitoring purpose. Furthermore, in this context, it would be useful to understand and verify the quality of different references (stratum 1) of timing networks, such as GNSS receivers.

Monitoring different nodes all around the distribution network also allows measuring data-traffic dedicated links (not related to timing or frequency distribution) just by setting a parallel network focused on obtaining information about the link performance. The existence of an innovative technology that exploits the White-Rabbit capabilities to reach the explained need, opens a new horizon for White-Rabbit applications, especially in the Finance Market.

The WR survey mode is a new functionality (developed for WR-Z v5.1 and later versions) that allows a WR interface to measure all parameters computed in a standard WR active port mode, but without synchronizing the internal system clock. An interface configured in “Survey” mode will have communication with a master WR reference. In practice, the interface will “try to lock” to its master WR reference, and all the parameters will be computed using the system clock as a time base.

This new configuration mode is available in WR-Z16 and WR-ZEN devices. The main purpose of this feature is to monitor the quality of a WR reference and its dedicated path to the slave WR node. The user can extract and monitor the survey information by choosing one of the different management alternatives or developing a monitoring tool which uses the exported data from the system.

Along with the possibility of configuring the survey mode in specific ports of the timing topology, new network design options emerge giving the possibility of including specific monitoring nodes located in strategic points of the infrastructure (Figure 1). This node will not interfere in the timing or frequency dissemination but will be used to measure the status and the performance of the time servers (working as time references), White-Rabbit nodes (for timing synchronization), and the end-nodes (which could interoperate with other standards such as PTP).

Target of the technical analysis

The technical analysis evidenced delves into the application of time distribution technology encountered within markets as finance, exploring mainly its critical role in enhancing precision and reliability. The focus of this analysis is to evaluate the performance of time-synchronization solutions, such as White-Rabbit (WR) and Precision Time Protocol (PTP), in scenarios demanding high accuracy and fault tolerance. Time synchronization is a cornerstone of modern finance, underpinning activities such as high-frequency trading.

The analysis is structured to address the following key areas:

Use cases

This section examines practical implementations of time distribution technologies, emphasizing their transformative impact on financial networks. Specific use cases will illustrate how these technologies enable seamless coordination across distributed systems in finance, ensuring accuracy, transparency, and resilience.

A network performance analysis over multiple nodes is performed with a focus on identifying bottlenecks and ensuring scalability. The analysis includes:

  1. Events Detection in Survey Mode Ports: Insights into the capabilities of survey mode ports for detecting and store time-critical events within the network.
  2. GNSS Redundancy Performance: Essential systems for maintaining synchronization reliability in GNSS signal disruptions scenarios, validating the time and frequency accuracy and stability offered by time servers and synchronization nodes with a sub-nanosecond resolution due to the White-Rabbit technology.

Annexes

Complementary technical details and data supporting the core analysis are presented in the annexes:

  1. White-Rabbit Accuracy Comparison: A comparative study of White-Rabbit’s performance between survey monitoring and traditional analog Pulse-Per-Second (PPS) delay measurement methods, highlighting the advancements in terms of accuracy and precision.
  2. Survey Mode Display in the WR-Z Web Interface: A demonstration of the WR-Z web interface’s capabilities for visualizing and managing synchronization settings for both White-Rabbit and PTP, showcasing user-centric tools for monitoring and diagnostics.

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