Timestamp Handling in Ethernet Protocol Stack Layers
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Solution Overview
Problem
Current timestamp protocols in computer networks face issues such as the need for multiple frame types, recomputation of checksums, and difficulties with security protocols like MACsec and IPsec, which complicate the measurement of transmission delays and synchronization of time-of-day clocks.
Innovation Solution
The solution involves adding timestamps at the physical layer and frame IDs at upper layers of the protocol stack, allowing for separate handling and recognition of sync packets and timestamps, ensuring accurate and efficient timestamping across the network, even with encrypted frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple frame types with multiple fields are used for timestamp protocols, then timestamp functionality is achieved, but frame complexity and checksum computation overhead increase
Solution Approach 1:
The patent segments the timestamp functionality by introducing a dedicated timestamp field within the existing Ethernet frame structure, rather than requiring multiple specialized frame types. This allows timestamp data to be carried alongside regular frame data, reducing complexity while maintaining measurement precision.
Solution Approach 2:
The patent makes the Ethernet frame structure universal by designing it to accommodate both regular data transmission and timestamp functionality through a shared frame format. The timestamp field can be optionally included in various frame types, allowing the same frame structure to serve multiple purposes without requiring separate specialized frames.
2Reliability
If timestamp protocols require recomputation of frame checksum values, then timestamp data integrity is ensured, but processing time and computational overhead increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing checksum values in the frame structure before transmission. When timestamps are added or modified, the system uses these pre-computed values and applies minimal adjustments rather than performing complete recomputation, significantly reducing processing time while maintaining data integrity through verified checksum validation.
3Reliability
If security protocols like MACsec or IPsec are applied to frames, then security is provided, but timestamp insertion and recognition become difficult or impossible
Solution Approach 1:
The patent introduces an intermediary approach by placing the timestamp field in a location within the Ethernet frame that is accessible before security encryption is applied. The timestamp is inserted at the Ethernet header level, which remains unencrypted even when payload data is protected by MACsec or IPsec. This allows timestamp operations to proceed independently of security protocol overhead while maintaining both security and timestamp functionality.
4Reliability
If frame encryption is applied, then security is maintained, but timestamp information may be lost or difficult to obtain
Solution Approach 1:
The patent segments the frame into encrypted and unencrypted portions, placing the timestamp field in the unencrypted Ethernet header segment. This allows the timestamp information to remain accessible and readable even when the payload is encrypted by security protocols, preventing information loss while maintaining security for the actual data being transmitted.
Data Source
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AI summary
In one embodiment, a physical (PHY) layer (lower protocol stack layer) of a device may add a timestamp to a received frame, and pass the frame and timestamp up the protocol stack toward a synchronization (sync) recognition layer (upper protocol stack layer). The sync recognition layer determines whether the frame relates to synchronization, and if so, places the timestamp into a data structure along with a frame association for recovery by follow up processing. Conversely, in another embodiment, the sync recognition layer may add to a frame for transmission a frame ID having an indication of whether to timestamp the frame and may pass the frame and frame ID down the protocol stack toward the FY layer. The FY layer determines whether the frame ID indicates that the frame is to be time stamped, and if so, places a timestamp corresponding to frame transmission into a data structure with the frame ID.