High-Speed Ethernet Timestamp Negotiation for Nanosecond Accuracy

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Solution Overview

Problem

High-speed Ethernet interfaces face operational complexity and inaccuracies in time stamping due to proprietary implementations by different vendors, leading to unpredictable time stamping errors of up to 100ns, which can cause failures in time-sensitive applications.

Innovation Solution

A protocol is introduced where network nodes announce and negotiate their time stamping capabilities using Link Layer Discovery Protocol (LLDP) with Type, Length, Value (TLV) fields, allowing for the selection of compatible time stamping operations to reduce errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If proprietary time stamping operations are implemented by different vendors, then device functionality is achieved, but time stamping accuracy deteriorates with errors of 100ns or more

Engineering Contradiction:
Improvevendor implementation flexibilityVSAvoidtime stamping accuracy
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent establishes a standardized time stamping capability advertisement mechanism using LLDP TLV fields that enables homogeneous interoperability between different vendors. By requiring all vendors to advertise their time stamping capabilities through a common protocol framework, the system achieves consistent behavior across heterogeneous implementations, reducing timestamp errors from 100ns to single-digit nanoseconds.

Inventive Principle:
Principle #33Homogeneity

Solution Approach 2:

The patent implements a feedback mechanism where network nodes advertise their time stamping capabilities to each other through LLDP messages. This allows nodes to receive information about their peer's capabilities and adjust their operations accordingly, selecting compatible time stamping modes to minimize errors. The capability advertisement serves as feedback that enables adaptive optimization of time stamping accuracy.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If time stamping capabilities are negotiated between nodes, then time stamping accuracy is improved, but device complexity increases due to additional protocol operations

Engineering Contradiction:
Improvetime stamping accuracyVSAvoidprotocol negotiation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent leverages the existing LLDP protocol framework to carry time stamping capability information, making the protocol universally applicable across different network devices. By using the established LLDP TLV structure rather than creating a new dedicated protocol, the solution achieves time stamping capability negotiation without adding significant operational complexity to the device stack.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent performs time stamping capability advertisement during the link establishment phase using LLDP messages before actual time-sensitive operations begin. This preliminary action allows nodes to pre-negotiate and select compatible time stamping modes, so that when time-critical operations occur, the complexity of capability negotiation is already resolved and does not interfere with real-time performance.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP4409781B1Protocol for increased accuracy time stamping interworking on high speed ethernet links
Publication Date: 2025.09.03 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4409781B1 patent drawingFigure 1~2
  • EP4409781B1 patent drawingFigure 3
  • EP4409781B1 patent drawingFigure 4~5

AI summary

A first network node is adapted to generate a first announcement indicating time stamping capabilities of the first network node. The first network node is further adapted to send the first announcement to a second network node.