From AI to sustainability, why our latest data centers use 400G networking

This post details the design and implementation of Dropbox's first data center architecture utilizing 400G ethernet. It covers the rationale for adopting 400G, including meeting the bandwidth requirements of AI workloads and sustainability goals. Key technical aspects discussed include the use of 400G DAC cabling for fabric core interconnections, achieving a 3x energy efficiency improvement per Gigabit. It also describes the selection of 400G-DR4 optics for top-of-rack interconnects to support both 100G and 400G switches up to 500 meters. Furthermore, the post explains the consolidation of the data center interconnect layer from three devices into one, enabled by 400G technology.