In the data center network system, the application of linear pluggable optics (LPO) modules has certain advantages in terms of cost, power consumption, and latency compared to traditional digital signal processor (DSP) modules. However, it also poses significant challenges to the end-to-end system design, including signal integrity (SI) design between devices and modules, the impact of optical-electrical link design consistency on the system, and the controversy over testability. These challenges currently hinder the practical implementation of LPO. This paper will showcase high-speed design and testing schemes for LPO systems from a system perspective. The paper will also present the testing results, data, and product architecture of a linear direct-drive switch in conjunction with an LPO module system.
With the rapid advancement of artificial intelligence-generated content and cloud computing technology, high performance computing and data center networks face increased demands for bandwidth capacity and forwarding latency. Upgrading network equipment to handle capacities up to 51.2 T and port rates up to 800G presents significant challenges in heat dissipation and power consumption design due to increased system density and complexity. To address this, the industry proposes a solution involving the removal of the optical digital signal processor (oDSP) chip from optical modules and adopting a linear direct-drive approach to reduce power consumption and data transfer latency.
Currently, mainstream 800G optical modules typically employ traditional re-timer solutions, incorporating oDSP for signal regeneration and digital signal compensation techniques. However, LPO modules offer advantages over oDSP solutions. These solutions reduce power consumption, latency, and cost while maintaining a pluggable module form, preserving the mature industry ecosystem.
In comparison to oDSP solutions, LPO modules offer lower cost, reduced latency, lower power consumption, and a mature ecosystem. Although LPO has many advantages, the technology has challenges including SI, non-linear LPO modules, standardization, and control of production metrics. SI is a big challenge and this paper will discuss how to reduce crosstalk, reflection, ISI, and so on.
To address SI challenges posed by removing oDSP from LPO modules, this paper focuses on optimizing high-speed channels in system design for better SI performance and enhancing link performance through system tuning. This includes sections on theory and application challenges, design and implementation, practical test results, industrial implementation, and future work plans.
The successful design and implementation of the 800G linear direct drive network system, with a strong emphasis on SI marks a pivotal advancement in high-speed data transmission. This work sets a new standard for future network infrastructure and provides a comprehensive foundation for further research and development in ultra-high-speed communication technologies.
The paper referenced here was part of DesignCon 2024 proceedings. To read the entire DesignCon 2024 paper, download the PDF.
