Ethernet Node Clock Synchronization via Reference Time Feedback
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Solution Overview
Problem
In Ethernet networks, time delays occur due to variations in transmit clocks between nodes, necessitating large internal FIFO memories to ensure data transmission accuracy, which increases transmission time through the network.
Innovation Solution
A method where each node receives a reference time to correct its local clock, synchronizing the transmit clock with a master clock, thereby reducing clock variations and eliminating the need for large FIFO memories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If nodes use independent transmit clocks without synchronization, then each node can operate autonomously, but clock variations between nodes increase causing larger FIFO memory requirements and longer transmission times
Solution Approach 1:
The patent implements a feedback mechanism where a master clock provides reference timing signals to slave nodes, and each slave node adjusts its local clock based on the received reference signals. This feedback loop ensures clock synchronization across the network while maintaining autonomous operation, as each node independently adjusts its clock based on the master's reference signals.
Solution Approach 2:
The patent creates a common timing reference level across all nodes by having slave nodes synchronize their local clocks to the master clock's reference signals. This equipotentiality in timing ensures that all nodes operate from the same time baseline, eliminating clock variations without requiring complex inter-node negotiation protocols.
2Adaptability or versatility
If nodes use independent transmit clocks without synchronization, then each node can operate autonomously, but clock variations between nodes increase requiring larger internal FIFO memories
Solution Approach 1:
The feedback mechanism allows slave nodes to continuously adjust their local clocks based on master clock reference signals, minimizing clock variations. This reduces the FIFO memory capacity needed at each node to the absolute minimum required for basic buffering, rather than requiring large memories to compensate for unsynchronized clock variations.
Solution Approach 2:
The patent changes the timing parameter of slave nodes by synchronizing their local clocks to the master clock frequency and phase. This parameter adjustment ensures that clock variations remain within minimal bounds, allowing FIFO memories to be kept small while still maintaining data integrity during transmission.
3Loss of time
If clock synchronization is implemented, then transmission time is reduced and FIFO memory requirements decrease, but system complexity increases due to master clock coordination
Solution Approach 1:
The patent segments the clock synchronization function by designating one node as the master clock and the others as slave nodes. This segmentation simplifies the overall system architecture, as the master node handles all timing reference generation and distribution, while slave nodes simply follow the provided references, dividing the complexity into manageable roles.
Solution Approach 2:
The master clock serves multiple functions: generating the reference timing signal, distributing it to all slave nodes, and providing a common synchronization source for the entire network. This multi-functionality reduces overall system complexity by consolidating timing control in a single node rather than requiring complex inter-node negotiation protocols.
Data Source
AI summary
A method for operating a node in a communications network comprises the following steps: The node receives a reference time via the communications network. A transmit clock of the node, which was determined for an earlier clock cycle on the basis of a local clock of the node, is compared with the reference time. The local clock of the node is corrected on the basis of the comparison result. On the basis of the corrected local clock a transmit clock is determined to be used by the node for the current clock cycle.