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What is 400G Optical MSA?
The 400Gbps Optical MSA specifies interoperable physical layer and FEC architectures for 400Gbps-class optical links used in AI and high-performance computing infrastructure. Based on PAM4 modulation and aligned with IEEE 802.3 specification as and methodologies, the MSA will aim to include link training and maintenance capabilities to improve the performance and reliability of the links. These features enable robust short-reach optical connectivity across scale-up accelerator fabrics and scale-out cluster interconnects.
As illustrated in the above image, the 400Gbps MSA is an fusion of two rates: One for 425Gbps PAM4 with FECo only and another for 453.75Gbps using both FECi and FECo