3.01

Who makes scale-up fabric for AI data centers

Scale-up fabric (GPU-to-GPU inside the rack/pod)

The fabric linking GPUs to each other inside a single rack or pod, separate from the switching fabric that connects racks to each other.

Scale-up fabric is the shortest, highest-bandwidth network in the data center: it lets GPUs inside the same rack or pod address each other's memory directly, rather than going through the scale-out switch fabric (3.02, 3.03). It sits upstream of the copper spine and backplane cartridges (3.10) that physically wire it together and, at higher speeds, of the optics and co-packaged approaches (3.04, 3.08) being evaluated as a copper replacement. AI training and inference workloads that split a single model across many accelerators depend on this fabric scaling in lockstep with GPU count, since it sets the ceiling on how large a tightly coupled GPU domain can get. An investor should watch whether a proprietary approach keeps its lead over open alternatives being pushed by a wider industry consortium, since that split determines how concentrated the supplier base for switch chips, cables, and connectors stays as pod sizes grow.

AI delta: Larger AI models split across more GPUs per training or inference job, which raises the bandwidth and reach demanded of the scale-up fabric linking them inside a rack or pod.

Appears at:Large colo / hyperscale buildingAI campusGW-class campus· cooling:any — Present wherever multi-GPU racks or pods exist; the fabric's reach and topology (single rack vs. multi-rack pod) scale with cluster size rather than being an enterprise feature.

Companies on this part (6)

CompanyRoleOwnershipTickerPrice1dConfidenceNote
Alphabet (Google)manufacturerpublicGOOGL320 USD-1.3%disclosedICI · source
AMDmanufacturerpublicAMD517 USD+2.2%inferredInfinity Fabric
Astera LabsmanufacturerpublicALAB257 USD+0.8%disclosedScorpio X · source
BroadcommanufacturerpublicAVGO322 USD-0.3%inferredscale-up Ethernet (Tomahawk Ultra)
NvidiamanufacturerpublicNVDA211 USD-0.7%disclosedNVLink/NVSwitch · source
UALink consortiummanufacturercooperativedisclosedmembers: AMD, Broadcom, Astera, Marvell, Cisco, hyperscalers · source

Who competes here

The same table read the other way: every company above competes for scale-up fabric sockets. Confidence tags matter — an inferred placement is a lead, not a confirmed rivalry.

Seen in real machines

scale-up fabric is named in 7 of the rack teardowns and supercomputer breakdowns on this site. Each line below is a piece of that machine. The companies shown are the ones named on that line, not necessarily the maker of this part.

Nearby parts

From the blog

Watch

What Exactly Does NVLink do for Machine Learning (featuring Exxact Workstation w/dual 3090s)
Jeff Heaton — explains NVLink's role as GPU-to-GPU scale-up interconnect
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Questions about scale-up fabric

What is scale-up fabric?
The fabric linking GPUs to each other inside a single rack or pod, separate from the switching fabric that connects racks to each other.
Which companies make scale-up fabric for AI data centers?
This catalog lists 6 companies on Scale-up fabric, 5 of them with listed equity: Alphabet (Google), AMD, Astera Labs, Broadcom, Nvidia, UALink consortium.
How does AI change demand for scale-up fabric?
Larger AI models split across more GPUs per training or inference job, which raises the bandwidth and reach demanded of the scale-up fabric linking them inside a rack or pod.
How reliable are these scale-up fabric supplier placements?
The 6 placements on this part break down as 4 disclosed, 2 inferred. "disclosed" means the company or a filing says so; "reported" comes from trade press or a reference-design list; "inferred" is a taxonomy lead with no citation yet.

Sources: placements without a source URL come from the taxonomy seed and are tagged accordingly. How this data is built.· Markdown · JSON