With the application of cloud computing, VR/AR, AI, 5G and other technologies, the bandwidth capacity of the global Internet has become very large. The flat two-layer leaf-spine (Leaf-Spine) architecture used in ultra-large-scale data centers requires a large number of interconnections, because each Leaf is fully interconnected with the spine to maximize non-blocking network connections between switches. Hardware accelerators, artificial intelligence, and deep learning functions in data centers all consume high bandwidth, forcing high-end data centers to rapidly move to next-generation interconnects operating at higher data rates. Next, ETU-LINK will introduce the development status of 800G optical modules to you.

An important sign of the emergence of 800G networks is that when the server-to-TOR layer switch reaches 200G, the TOR-Leaf/Spine layer has to use the PSM4 4×200G structure. Deploying 200G servers requires 800G bandwidth.

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In the 800G pluggable MSA, two solutions are firstly defined, namely 800G-SR8 and 800G-FR4. In the SR8 scenario, in order to consider more technological advances and obtain a competitive SMF solution, in the short-distance application scenario, cost is the focus of attention. The 800G optical module can use 800G SR8. From 400G-SR8 In the evolution to 800G-SR8, the rate of 100G per channel may limit the solution based on multimode fiber (MMF). According to the theoretical model used in IEEE, we can estimate that when the baud rate is as high as 50G, the transmission distance that MMF can support does not exceed 50m. The limiting factor comes from the modulation bandwidth of the VCSEL and the intermodal dispersion of the MMF. By optimizing devices, fiber media, and enhanced DSP algorithms, 100m transmission can be achieved at the expense of higher costs, higher delays, and greater power consumption. Therefore, the MSA pluggable 800G optical module working group recommends the use of single-mode transmission technology to realize the interconnection of 800G-SR8 scenarios.