Utilizing Both Backplane and Cable Connections in Server Systems: Viability and Challenges in a Common AI Server Design
Su Thonas, Ju Huafang, Yang Tina · 2024
Following the introduction of the DC-MHS1(Data Center Modular Hardware System) and AI (Artificial Intelligence) servers, the adoption of cabling topologies has become increasingly prevalent and indispensable. Within DC-MHS design, the Host Process Module (HPM) necessitates cabling for inter-module connectivity. In AI servers, components such as the HPM, PCI Express (PCIe) switch board, and UBB (Universal Baseboard) may not reside on the same chassis floor, necessitating vertical connections either through traditional backplane design or cables to link boards and modules. These connections are critical for high-speed signal transmission, exemplified by technologies like PCIe 5.02operating at 32 GT/s. Driven by escalating computing demands, the industry is eagerly anticipating PCIe 6.0 and exploring advancements towards PCIe 7.0, which runs at 64 GT/s and 128 GT/s respectively. This paper presents a generalized connection topology for HPM, PCIe switch board, and UBB. Simulation and measurement results are included to elucidate common challenges encountered in cabling topologies.