Multi-Lane Ethernet Alignment Marker Handling After FEC
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Solution Overview
Problem
Current Ethernet architectures are limited in flexibility and cannot be easily extended to higher bandwidths beyond 100 G, leading to issues such as misalignment of alignment markers (AMs) and incorrect decoding at the receive end, especially when transitioning to higher rates like 400 G, where the transmission bandwidth of serializer/deserializer (Serdes) is not matched and AMs become disorganized due to Forward Error Correction (FEC).
Innovation Solution
A data processing method that inserts multiple alignment markers into a transcoded and scrambled data stream, adaptively allocates them to physical coding sublayer (PCS) lanes, performs FEC encoding, and delivers the data to physical medium attachment (PMA) lanes with bit width conversion and idle data insertion to ensure continuous and complete AMs, allowing correct decoding at the receive end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Ethernet interface uses higher rate (e.g., 400 G) to increase bandwidth, then transmission capacity is improved, but alignment markers become disorganized and cannot be correctly decoded
Solution Approach 1:
The data stream is divided into multiple lanes (e.g., 16 lanes for 400G) with alignment markers inserted independently in each lane. This segmentation allows each lane to be processed separately while maintaining overall synchronization, preventing marker disorganization at higher speeds.
Solution Approach 2:
Alignment markers are inserted into the data stream before FEC encoding and lane allocation. This preliminary insertion ensures markers are positioned correctly in the original stream, allowing the receive end to reconstruct proper alignment even after transmission processing.
2Reliability
If Forward Error Correction (FEC) is applied to improve transmission reliability, then error correction capability is improved, but alignment markers become disorganized and cannot be identified
Solution Approach 1:
The FEC encoding process is applied separately to each lane while preserving the integrity of alignment markers within those lanes. This segmented approach allows FEC to correct errors without disrupting marker positions across the entire data stream.
Solution Approach 2:
Alignment markers serve as intermediary reference points that guide the receive end through FEC decoding and lane remapping processes. These markers act as mediators between the transmitted data and the reconstruction process, ensuring proper alignment is maintained despite FEC processing.
3Productivity
If data is allocated to multiple PCS lanes to increase bandwidth utilization, then transmission capacity is improved, but alignment markers cannot be correctly remapped at the receive end
Solution Approach 1:
Alignment markers are inserted and positioned before data is allocated to multiple PCS lanes. This preliminary positioning creates a reference framework that simplifies the remapping process at the receive end, as markers serve as predetermined anchors for reconstructing the original data sequence.
Solution Approach 2:
The receive end uses alignment markers as feedback references to determine correct lane remapping. By detecting marker positions in received data from multiple lanes, the system automatically adjusts remapping to reconstruct the original sequence, simplifying the operation of handling multi-lane data.
Data Source
AI summary
A data processing method, a data transmit end, and a data receive end are presented. The data processing method includes inserting multiple alignment markers (AMs) into a first data stream, where the first data stream is a data stream that is transcoded and scrambled after being encoded at a physical layer; adaptively allocating the first data stream that includes the AMs to multiple physical coding sublayer (PCS) lanes to obtain second data streams; performing forward error correction (FEC) encoding on the second data streams on the multiple PCS lanes to obtain third data streams; and delivering the third data streams to multiple physical medium attachment sublayer (PMA) lanes according to an input bit width of a Serdes to obtain multiple fourth data streams, each fourth data stream includes at least one complete and continuous AM, and the at least one AM is an AM in the multiple AMs.