Clock Synchronization Using Packet Congestion Information
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Solution Overview
Problem
PTP-unaware networks face challenges in reliably synchronizing clocks due to variable delays caused by network congestion, which existing transparent clock technologies cannot address without specialized equipment deployment.
Innovation Solution
Utilize congestion information within packets to determine and compensate for delays in clock synchronization by adjusting the weight applied to timestamps based on congestion indicators, allowing precise synchronization without relying on end-to-end heuristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If PTP-unaware networks use legacy equipment without transparent clock support, then device compatibility and ease of deployment are improved, but clock synchronization accuracy deteriorates due to variable delays from network congestion
Solution Approach 1:
The patent introduces congestion information as an intermediary element that mediates between the synchronization packets and the network congestion condition. This intermediary carries delay information about packet transmission through the network, allowing receivers to compensate for congestion-induced delays without requiring transparent clock support in legacy equipment. The intermediary enables accurate synchronization while maintaining compatibility with existing devices.
Solution Approach 2:
The patent changes the parameter used for synchronization by incorporating congestion information into the synchronization packets. Instead of relying solely on timestamp-based synchronization that is vulnerable to network congestion, the system modifies the synchronization mechanism to include delay compensation parameters derived from congestion indicators, thereby maintaining accuracy in PTP-unaware networks.
2Measurement precision
If network devices adjust timestamp weights based on congestion information, then clock synchronization accuracy is improved, but packet processing complexity increases
Solution Approach 1:
The patent applies partial action by adjusting timestamp weights only for packets affected by congestion, rather than processing all packets with full complexity. The system determines congestion status and applies weight adjustments selectively, reducing the processing burden compared to continuously analyzing all packet characteristics. This partial approach maintains synchronization accuracy while limiting the increase in processing complexity to only when needed.
Data Source
AI summary
A network device includes control logic coupled to a receiver. The control logic detects an synchronization packet received via the receiver from a second network device over a network that is precision time protocol unaware. The control logic determines that a portion of the synchronization packet is asserted, indicating that the synchronization packet has incurred congestion traversing the network. The control logic adjusts, based on an assertion of the portion, a weight applied to timestamps associated with sending and receiving the synchronization packet in performing clock synchronization with the second network device.