51.2T CPO Switch Practice And Challenge

Author: Ting-Chiun Lin (Tim), Director of Engineering, MICAS Networks; Shaun Rasmussen, Strategic Planning Director, MICAS Networks Collection: 2023 Global Summit - Networking

Summary

MICAS Networks presents their next-generation 51.2 Tbps Co-Packaged Optics (CPO) switch system built on Broadcom's Bailly CPO Tomahawk 5 switch ASIC. The 4RU chassis provides 128x 400G-FR4 optical ports using LC duplex connectors and 16 Remote Laser Modules (RLMs), achieving approximately 1,300 watts total system power -- roughly 30% lower than traditional pluggable optics systems. The design addresses three fundamental CPO engineering challenges: optical path stability, thermal management with concentrated heat sources around the ASIC, and the complexity of fiber-dense manufacturing and assembly.

The presentation details specific engineering innovations including an onboard fiber tray system to reduce optical fiber vibration from cooling airflow, a customized fiber kit that simplifies connector count to just three types (FAU, RLM MPO, and breakout MPO), and a novel thermal design using a larger heatsink (299.2x135mm, 92.9mm tall with D8x10 heat pipes) that achieves 0.079 degrees C/W thermal resistance with only 152 CFM airflow -- comparable to the conventional TH5 heatsink's 0.080 degrees C/W at 226 CFM. Manufacturing requires 1K class workbenches and 10K class clean rooms with microscopic examination of every connector interface. MICAS also introduced its broader product portfolio spanning 1G to 400G switches across Broadcom Tomahawk 3/4/5, Jericho, and Trident silicon, with SONiC as the primary NOS.