With data consumption and processing demands surging, the demand for faster, more efficient Data Center Interconnects (DCI) is at an all-time high. As the industry pushes beyond 224Gb/s per lane, emerging technologies and next-gen architectures are being developed to deliver scalable, power-efficient, and reliable solutions—without compromising on cost.
Challenges ahead when determining the “Next” data rate
As data rates exceed 224Gb/s per lane, choosing the right modulation scheme becomes critical for optimizing performance, power efficiency, and spectral usage. PAM-4 (Pulse Amplitude Modulation with four levels) is currently the industry standard for high-speed Ethernet, delivering twice the data rate of NRZ (Non-Return-to-Zero) without increasing the baud rate. However, pushing beyond PAM-4 introduces greater noise sensitivity and signal integrity issues. Emerging alternatives like PAM-6, PAM-8, or even coherent optical technologies are being explored—each presenting trade-offs in complexity, power consumption, and cost. As data center networks evolve, system architects must weigh these options carefully to strike the right balance between speed, efficiency, and practical deployment.
Considerations regarding the “Next” data rate
Traditionally, high-speed interconnects have relied on backplane connections for in-rack communication and pluggable optical transceivers for longer intra-data center links. However, as data rates reach and surpass 224Gb/s, electrical channel losses have emerged as a major limitation. This has driven a shift toward co-packaged solutions, where optics or copper interconnects are integrated directly with the switch ASIC.
Co-Packaged Copper (CPC): CPC presents an attractive option for short-reach connections within data centers (typically under 2km). By minimizing the need for power-hungry optical conversions, CPC enhances signal integrity while reducing both latency and power consumption. Though its range is shorter than that of optical solutions, CPC is well-suited for intra-rack and short inter-rack applications.
Co-Packaged Optics (CPO): Co-Packaged Optics is re-emerging as a compelling solution for high-speed intra–data center interconnects. By integrating optical components directly onto the same substrate as the ASIC, CPO minimizes electrical losses and delivers significant gains in energy efficiency. However, its adoption also introduces new challenges—particularly in thermal management, integration complexity, and manufacturability.
As data rates exceed 224 Gb/s, designers must carefully weigh trade-offs. Key considerations include:
- Power Efficiency:
Power consumption is a critical constraint in next-generation data centers. CPO and Co-Packaged Coherent (CPC) technologies reduce power per transmitted bit, offering a clear advantage over traditional pluggable optics. - Cost Factors:
While co-packaged solutions require novel manufacturing techniques and materials—potentially increasing initial costs—scaling adoption and manufacturing maturity could lower these costs over time through economies of scale and improved yields. - Reliability and Maintainability:
A key concern with CPO is reduced serviceability. Unlike pluggable optics that offer hot-swappability, CPO modules typically require complete replacement, which can complicate maintenance and increase operational overhead.
The shift beyond 224 Gb/s marks a pivotal moment in the evolution of data center interconnects. While Co-Packaged Coherent (CPC) and Co-Packaged Optics (CPO) present compelling options, hybrid architectures that integrate both technologies may offer the best balance of reach, power efficiency, and cost-effectiveness. Advancements in materials science, thermal management, and packaging techniques will play a decisive role in enabling these high-speed solutions.
As hyperscale's and network equipment providers continue to drive demand for greater performance and efficiency, the advancement of data center interconnect (DCI) technologies will be central to powering the future of cloud infrastructure, AI workloads, and global digital connectivity.
