AI Infusion: The Next Wave of Data Center Networking

Investments in AI have skyrocketed, and AI computing clusters are at the front end of a huge ramp in growth. Industry analyst LightCounting expects a nearly 30% compound annual growth rate (CAGR) in fiber transceiver sales for AI clusters through 2028. However, data center managers face a range of challenges when deploying AI clusters, including power, cooling, geography, latency, and deployment speeds. These factors will ultimately drive the network architecture and type of cabling required throughout all types of data centers — from enterprise designs to large hyperscale builds.

Connectivity and Cabling for AI Networks

Climbing Data Rates

As you can imagine, AI is driving higher and higher data rates in data centers. Today, 200 Gb/s is most likely the slowest data rate in a large-scale AI cluster. In fact, 400 Gb/s and 800 Gb/s are more typical, and 1.6 Tb/s is expected to gain adoption in the near future.

Naturally, the physical interfaces of these data rates lead to different physical connectors and termination requirements. Connection choices at the higher data rates are largely driven by multi-source agreements (MSAs) between vendors, the most recent of which are the OSFP and QSFP-DD800 MSAs. Connection at the 400G data rate is dominated by traditional 12-fiber MPO connectors and LC connectors, with volume on the LC duplex FR4, and MPO-based DR4 and SR4 parallel optics. Additionally, at this rate, multimode interfaces will drive the adoption of angled physical contact (APC) to reduce reflectance or return loss. The angled end-face geometry improves return loss and performance, supporting higher data rates like 800G and beyond.

Cabling Connections

AI clusters consolidate a large number of fibers within racks and rows. From a cabling design perspective, one option for addressing such a high volume is to install direct connections from the AI systems to the switching fabric, using either active optical cables (AOCs) or discrete MPO array cords. This is the most straightforward approach, but it does create a significant volume of cable in the cable tray and within the racks themselves. Additionally, the QSFP (or OSFP) connector attached to the end of the AOC needs to be routed through the cable pathway. Pulling the transceivers through the pathways can be cumbersome, and the installer must be careful to avoid damage.