Packet Forwarding via Virtual Phase Difference Measurement
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Solution Overview
Problem
The implementation of precise time synchronization in Time-Sensitive Networking (TSN) systems is challenging due to the difficulty in achieving precise time synchronization between network devices and the accumulation of clock jitter, which increases deployment costs and complexity.
Innovation Solution
A packet forwarding method that determines a phase difference between switching times of buffers in different network devices, considering link delay, allowing for queuing and forwarding of data packets without the need for time synchronization, by using messages to measure and calculate the phase difference and schedule data packets accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If precise time synchronization is implemented in TSN systems, then deterministic delay characteristics and time-based synchronous data transmission are achieved, but deployment complexity and costs increase due to clock jitter accumulation
Solution Approach 1:
The patent extracts the time synchronization requirement from the TSN system by introducing a virtual time synchronization mechanism. Instead of requiring actual clock synchronization between devices, the system creates virtual synchronized time references through message exchange and calculation, thereby achieving deterministic delay characteristics without the complexity of precise physical time synchronization.
Solution Approach 2:
The patent introduces a virtual time reference message as an intermediary between network devices. This message carries virtual time synchronization information that mediates the timing relationships between devices without requiring their actual clocks to be synchronized, thus reducing deployment complexity while maintaining reliability.
2Productivity
If IEEE 802.1AS time synchronization protocol is used for CQF mechanism, then round robin scheduling between multiple buffers is achieved, but network deployment difficulty and costs increase due to precise time synchronization requirements
Solution Approach 1:
The patent creates a virtual copy of the time synchronization function through message exchange. Instead of requiring actual time synchronization, the system copies the essential timing relationship information through virtual time reference messages, enabling round robin scheduling without the need for complex time synchronization protocol deployment.
Solution Approach 2:
The patent changes the parameter representation from absolute time values (requiring synchronization) to relative phase differences and time offsets. By transforming the time reference parameters into differential forms that can be calculated from message exchange, the system achieves round robin scheduling while simplifying deployment.
3Stability of the object's composition
If all network devices perform time synchronization, then consistent round robin time and frequency are achieved across buffers, but clock jitter accumulation increases implementation difficulty
Solution Approach 1:
The patent segments the time synchronization function into individual device-specific virtual time references. Instead of requiring all devices to synchronize to a common time source, each device maintains its own virtual time reference based on local calculations from received messages, achieving consistency without the complexity of global synchronization and reducing clock jitter accumulation.
Data Source
AI summary
A packet forwarding method includes a first network device receiving a first message from a second network device via a second egress port of the second network device, where the first message measures a phase difference, and where the phase difference is a phase difference between a switching time of one of a plurality of first buffers of a first egress port of the first network device and a switching time of one of a plurality of second buffers of the second egress port of the second network device with a link delay taken into consideration. The first network device determines the phase difference based on the first message. Then, the first network device schedules, based on the phase difference, a second data packet sent via the first egress port.