06/09/2026
AI Clusters Shift Network Spending Toward Back-End Fabrics: AI infrastructure spending crossed a notable line in the second quarter of 2026: revenue from switches connecting accelerators inside AI back-end networks exceeded sales of front-end data center switches for the first time. The shift puts high-speed fabric economics, supply availability, and vendor positioning closer to the center of infrastructure purchasing decisions across hyperscale and enterprise deployments.
Dell’Oro Group says the crossover happened only three years after AI back-end networking emerged as a distinct spending category. That speed is more important than the symbolic ranking. Front-end networks serve conventional server, storage, user, and application traffic across enormous installed estates. Back-end fabrics are narrower in purpose, but AI clusters are forcing operators to buy far more bandwidth per compute node, at speeds that would have looked extreme in mainstream data centers only a few product cycles ago.
The money is following the architecture. Accelerators are expensive, and idle accelerators are worse. Network performance inside large training and inference clusters increasingly determines whether costly GPU capacity can be used efficiently. That makes switching less of a supporting line item and more closely tied to the economics of the compute investment itself. For infrastructure buyers, procurement decisions now reach beyond port counts and familiar enterprise vendor relationships. Availability, interoperability, topology design, optics, software, congestion behavior, and upgrade timing all carry direct utilization consequences.
Ethernet Takes More Ground
Ethernet strengthened its lead in AI back-end networks during the quarter, according to Dell’Oro, with 800 Gbps equipment accounting for the vast majority of Ethernet switch shipments and revenue. The research firm says 1.6 Tbps products began sampling and should ramp during the second half of 2026.
This is becoming a vendor diversification story as much as a protocol story. Ethernet gives operators a broader supplier field and a standards-based technology base, useful when cluster builds are constrained by component availability. Dell’Oro expects the market to remain supply-constrained rather than demand-constrained for at least another one to two years. That means share gains may reflect who can ship, not only whose architecture buyers prefer.
InfiniBand is not disappearing. Its sales more than tripled in the first quarter of 2026 as NVIDIA’s 800 Gbps Blackwell Ultra systems ramped, although Dell’Oro said some of that demand likely came from upgrades to existing deployments. Ethernet, meanwhile, represented about two-thirds of data center switch sales inside AI clusters in that quarter.
Vendor Rankings Shift
Celestica led Ethernet AI back-end switch sales in the second quarter, followed closely by NVIDIA. Arista ranked third, while Cisco placed fourth and gained the most share, Dell’Oro said. The firm also noted that Arista’s position would have been closer to the leaders had deferred AI revenue been included.
Those rankings need careful reading. AI networking revenue is increasingly exposed to the cadence of giant cluster deployments, customer acceptance schedules, silicon availability, and the accounting treatment of large projects. Quarterly market share can move sharply without indicating a durable change in technical preference.
Still, the competitive map is widening. In 2025, Dell’Oro said Amazon, Microsoft, Meta, Oracle, and xAI were adopting Ethernet for AI networks, while Celestica and NVIDIA together held roughly half of Ethernet switch sales in AI clusters. The direction favors suppliers that can combine high-radix hardware, advanced silicon, optics, operating software, and reliable delivery at enormous scale.
Buyers Face Faster Cycles
The uncomfortable part for operators is refresh velocity. Many organizations are still absorbing 400 Gbps deployments while AI clusters are standardizing around 800 Gbps and suppliers are preparing 1.6 Tbps systems. Back-end networks also introduce different failure domains, cabling densities, power demands, telemetry requirements, and congestion-management assumptions than conventional leaf-spine environments.
Dell’Oro expects scale-up Ethernet use cases to begin emerging in the second half of 2026, adding another layer to a market already dominated by scale-out and scale-across deployments.
That could expand the addressable market again. It also raises harder questions about where Ethernet can displace proprietary or tightly integrated interconnects without creating performance penalties. Buyers may want openness. GPU economics may force a less ideological answer.
For now, the clearest signal is spending allocation. More switch revenue is being generated inside AI compute fabrics than at the traditional data center front end. The next transition is already arriving at 1.6 Tbps, before many operators have finished operationalizing 800 Gbps.
Executive Insights FAQ
Why does back-end switching now deserve more board-level attention?
Networking is becoming a larger share of AI infrastructure economics, affecting accelerator utilization, deployment schedules, vendor concentration, and the return profile of cluster investments.
Does Ethernet’s lead make InfiniBand strategically irrelevant?
No. InfiniBand remains significant in tightly integrated AI systems, but Ethernet benefits from supplier diversity, familiar operations, and broader ecosystem support as deployments scale.
What should infrastructure buyers prioritize in procurement?
Buyers should weigh delivery certainty, optics availability, software maturity, congestion performance, interoperability, and upgrade paths alongside headline throughput and acquisition cost.
How should vendors interpret the changing market-share rankings?
Quarterly rankings increasingly reflect shipment timing, deferred revenue, component access, and hyperscale project cycles, so sustained ex*****on matters more than a single reporting period.
What is the biggest operational risk in the 800 Gbps transition?
The risk is not raw bandwidth alone. Cabling density, optics reliability, telemetry, power, thermal limits, and troubleshooting complexity can erode expected utilization gains.
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