Timestamp Insertion via Error Detection Tag in Network Devices
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Solution Overview
Problem
Conventional IEEE 1588 protocols struggle to perform timestamp functions on network packets encrypted with MACSec, as they require parsing in the IEEE 1588 format, which the physical layer cannot handle, hindering time synchronization in network devices.
Innovation Solution
The solution involves generating and inserting timestamps into network packets using an error-detection tag, allowing timestamp generation and synchronization irrespective of packet format, enabling timestamping functionality even for encrypted packets by replacing the error detection field with an error detection tag and inserting the timestamp into it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the physical layer parses packets using standard IEEE 1588 packet format, then timestamp accuracy is improved, but compatibility with encrypted MACSec packets deteriorates
Solution Approach 1:
The patent introduces an intermediary mechanism where the MAC layer (not the physical layer) performs timestamp insertion into packets. This intermediary approach allows timestamping to occur at a layer that can access both the packet data and timing information, resolving the conflict between needing to parse packet format for accuracy and needing to handle encrypted packets that cannot be parsed by the physical layer.
Solution Approach 2:
The patent segments the timestamping function from the physical layer parsing function. Instead of requiring the physical layer to both parse packets and generate timestamps, the invention separates these functions: the physical layer handles transmission and timing, while the MAC layer handles packet formatting and timestamp insertion. This segmentation allows each layer to operate independently without compromising the other.
2Loss of time
If timestamps are taken at the physical layer edge close to network medium, then time difference minimization is improved, but ability to handle encrypted packets deteriorates
Solution Approach 1:
The MAC layer acts as an intermediary that receives timing signals from the physical layer and independently inserts timestamps into packets. This eliminates the need for the physical layer to parse encrypted MACSec packets, reducing device complexity while maintaining accurate timestamping through the intermediary's access to both timing and packet information.
Solution Approach 2:
The MAC layer performs timestamp insertion autonomously using timing information provided by the physical layer, without requiring the physical layer to perform complex packet parsing. This self-service approach at the MAC layer simplifies the physical layer's function to basic transmission and timing signal generation.
Data Source
AI summary
A method of generating timestamp information irrespective of a packet format include generating an egress timestamp corresponding to a time at which a first egress packet associated with a synchronization event is transmitted to a network medium; storing the egress timestamp in a memory based on an egress identifier; and transmitting a second egress packet associated with the synchronization event with the stored egress timestamp being included in the transmitted second egress packet for timing synchronization in the network medium. The method also includes receiving an incoming packet from the network medium; generating an ingress timestamp corresponding to a time at which the incoming packet is received; replacing an error detection field included in the incoming packet with an error detection tag; inserting the ingress timestamp into the error detection tag; and providing the incoming packet with the ingress timestamp to a processor for synchronization of a local clock.