FlexE Shim Time Transfer via Dedicated Synchronization Channel
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Solution Overview
Problem
Current time transfer methods over Flexible Ethernet (FlexE) face challenges due to Constant Time Error (CTE) and uncertainty introduced by elastic First-in-First-out (FIFO) delays and adaptation processes, which affect the accuracy of time synchronization across nodes.
Innovation Solution
Implementing a time transfer method that uses the FlexE shim for synchronization, with Precision Time Protocol (PTP) messages communicated through a synchronization message channel within the FlexE overhead, utilizing frame or multi-frame boundaries as timestamp points of reference, and encoding data as 64b/66b blocks to minimize uncertainty and variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If elastic FIFO delays and adaptation processes are used in FlexE interfaces, then adaptability and versatility are improved, but time transfer accuracy and synchronization precision deteriorate due to Constant Time Error (CTE) and uncertainty
Solution Approach 1:
The patent introduces a dedicated synchronization message channel as an intermediary within the FlexE overhead structure to carry PTP messages separately from the elastic FIFO data paths. This mediator enables precise time transfer by bypassing the adaptive buffering processes that cause CTE, while still allowing the main FlexE interface to maintain its adaptability for various Ethernet rates and configurations.
Solution Approach 2:
The patent segments the FlexE interface functionality by separating the synchronization channel from the data transmission paths. The FlexE overhead is divided into dedicated synchronization fields that carry time transfer information independently from the elastic FIFO buffers used for adaptive rate matching, allowing simultaneous operation of adaptable data paths and precise timing references.
2Ease of operation
If PTP messages are transmitted through FlexE client adaptation processes, then ease of operation is improved, but time synchronization precision deteriorates due to uncertainty in adaptation delays
Solution Approach 1:
The patent creates a dedicated synchronization message channel within the FlexE overhead structure that acts as an intermediary for PTP message transmission. This separate channel bypasses the FlexE client adaptation processes and elastic FIFO buffers, eliminating the uncertainty in adaptation delays while maintaining ease of operation through standardized PTP protocols.
Solution Approach 2:
The patent extracts the time synchronization function from the FlexE client adaptation process by allocating specific overhead fields exclusively for PTP messages. This extraction removes the source of timing uncertainty (the adaptive buffering) from the critical time transfer path, while the rest of the system continues to benefit from flexible adaptation.
3Device complexity
If FlexE overhead is used for synchronization message channel, then device complexity is reduced, but time transfer accuracy may be affected by overhead encoding variations
Solution Approach 1:
The patent makes the FlexE overhead structure multi-functional by using it to carry both data transmission control information and time synchronization messages through the same physical infrastructure. This universal use of overhead fields reduces device complexity by eliminating separate synchronization hardware, while the deterministic encoding of overhead blocks maintains time transfer accuracy.
Solution Approach 2:
The patent changes the parameter of message transmission medium from separate dedicated synchronization hardware to FlexE overhead fields, reducing complexity. To maintain accuracy despite encoding variations, the patent uses deterministic timestamp points based on fixed FlexE frame boundaries and applies appropriate time domain adjustments to compensate for known overhead processing delays.
Data Source
AI summary
Time transfer systems and methods implemented in a first node steps of communicating a stream of encoded blocks with a second node; and communicating synchronization messages with the second node via a synchronization message channel in overhead associated with the stream of encoded blocks, wherein the synchronization messages are utilized for synchronization of a clock at the second node. Each block in the stream of encoded blocks can be one of a data block and an overhead block.