Network Interface Timestamping for Precise Multicast Synchronization
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Solution Overview
Problem
Existing network adapters fail to provide precise multicast timestamping, leading to synchronization quality degradation due to varying timing of packet copies in multicasting, which affects synchronization protocols and quality of service.
Innovation Solution
Determine receive timestamps for each subscriber entity, either using the transmission timestamp of the first subscriber or adding a preset offset value, enabling accurate synchronization by sending identical timestamps to all subscribers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If packet copies are transmitted to multiple subscribers using hardware duplication, then multicast functionality is achieved, but timing offsets occur between different packet copies leading to synchronization quality degradation
Solution Approach 1:
The patent introduces a timestamp correction mechanism that acts as an intermediary between the original transmission timestamp and the timestamp received by each subscriber. The system calculates timing offsets for each packet copy and applies corrections to ensure all subscribers receive accurate timestamps reflecting their actual reception time, thereby resolving the synchronization issue without compromising multicast functionality
Solution Approach 2:
The patent changes the timestamp parameter by introducing offset values that compensate for the time differences between packet copy transmissions. Instead of using the original transmission timestamp for all subscribers, the system dynamically adjusts the timestamp parameter for each subscriber based on their specific reception timing, ensuring synchronization accuracy across all recipients
2Device complexity
If identical transmission timestamp is provided to all subscribers, then processing complexity is reduced, but synchronization quality deteriorates due to timing offsets in packet copies
Solution Approach 1:
The patent segments the timestamp provision process by creating different timestamp values for different subscribers based on their specific reception characteristics. Instead of providing a single identical timestamp to all subscribers, the system divides the timestamping function into subscriber-specific segments, calculating and providing customized timestamps that account for individual timing offsets, thereby maintaining synchronization quality without excessive complexity
3Measurement precision
If precise timing tracking is implemented for each packet copy, then synchronization quality improves, but device complexity and processing overhead increase
Solution Approach 1:
The patent implements a self-service mechanism where the system automatically calculates and applies timestamp corrections for each packet copy without requiring complex external intervention. The timestamp correction logic operates autonomously within the network interface device, using built-in timing information to generate corrected timestamps for each subscriber, thereby achieving precise timing tracking with minimal additional hardware complexity
Data Source
AI summary
A network interface device includes a local register and packet processing circuitry coupled to the local register. The packet processing circuitry is to: capture a network packet transmitted by a software application running on an integrated computing system; capture, at time of transmission of the network packet, a value of a physical clock as a receive timestamp for subscriber entities that are running on the integrated computing system; store the receive timestamp in the local register; associate the receive timestamp from the local register with a first packet copy of the network packet; insert the first packet copy to a first receive pipeline of a first subscriber entity; associate the receive timestamp from the local register with a second packet copy of the network packet; and insert the second packet copy to a second receive pipeline of a second subscriber entity.