Multicast Packet Timestamping for Consistent Subscriber Synchronization
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Solution Overview
Problem
Existing network adapters fail to accurately track the timing of multicast packet copies due to serial generation, leading to synchronization quality degradation in multicasting protocols, especially as network speeds increase.
Innovation Solution
Determine receive timestamps for each subscriber by using a network adapter to generate and transmit packet copies with either the transmission timestamp of the first subscriber or an offset value, ensuring all subscribers receive consistent timestamps for precise synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If network adapters generate multicast packet copies serially, then device complexity is reduced, but measurement precision of transmission timing deteriorates
Solution Approach 1:
The patent uses software-based packet copying to create multiple multicast copies from a single original packet. The network adapter generates one original packet with a precise transmission timestamp, then creates multiple software copies that all reference the same timestamp value. This approach avoids the need for complex hardware duplication while maintaining accurate timing information across all multicast subscribers.
Solution Approach 2:
The patent combines the timestamp generation function with the packet copying operation. Instead of generating separate timestamps for each packet copy through complex hardware, the system generates a single timestamp and merges it with all packet copies. This consolidation simplifies the hardware requirements while ensuring all subscribers receive consistent timing information.
2Manufacturing precision
If packet copies are generated serially, then manufacturing precision is improved, but synchronization quality deteriorates
Solution Approach 1:
The patent changes the timing parameter representation by using a single reference timestamp for all packet copies instead of generating separate timestamps for each copy. This parameter change ensures that all subscribers receive packets with consistent timing information, maintaining synchronization quality while allowing serial packet generation.
Solution Approach 2:
The patent introduces a software intermediary layer that handles packet copying and timestamp assignment. This software mediator ensures that all packet copies receive the correct reference timestamp even though they are generated serially, thereby maintaining synchronization quality without requiring simultaneous hardware generation.
3Productivity
If transmission speeds increase, then productivity is improved, but measurement precision of timing deteriorates
Solution Approach 1:
The patent applies preliminary action by generating the transmission timestamp before creating any packet copies. The original packet receives the timestamp at the moment of transmission, and this timestamp is then reused for all subsequent software copies. This preliminary timestamp generation ensures accurate timing measurement even as transmission speeds increase and packet generation becomes more rapid.
Data Source
AI summary
A network interface device includes packet processing circuity to capture a network packet transmitted by a software application running on a computing device and capture, at time of transmission of the network packet, a value of a physical clock as a receive timestamp for subscriber entities of the computing device. The circuitry associates the receive timestamp with a first packet copy of the network packet and inserts the first packet copy to a first receive pipeline of a first subscriber entity. The circuitry associates the receive timestamp with a second packet copy of the network packet and inserts the second packet copy to a second receive pipeline of a second subscriber entity.