The company that sells the most Ethernet switching into data centers does not sell switches for a living. Nvidia booked $2.1bn of data-center Ethernet switch revenue in the March quarter, 21.5% of the market against Arista Networks' 20.7%, taking the top revenue position in a category Arista has defined for a decade.

It took it by not selling switching as such. Nvidia's Spectrum-X ships inside an integrated package of GPUs, switches, data-processing units and cables, which is how an accelerator vendor captures the network content that used to be bid separately. Below Arista, Broadcom is shipping Tomahawk 6, a 102.4-terabit single-chip switch supporting up to 512 ports at 200 gigabits, positioned explicitly to give hyperscalers an open fabric without proprietary lock-in. The pool being fought over is large: Dell'Oro Group expects data-center switch sales into artificial-intelligence back-end networks to exceed $100bn by 2030, roughly $80bn of it over the next five years.

The business is not the problem

Arista, which sells high-performance Ethernet switches and routers running its own operating system to cloud, telecom and financial customers, has accelerated for four straight quarters — from 27.5% year-over-year revenue growth to 37.7% in the June quarter, its first $3bn quarter at $3.036bn. On the August 4 call it raised 2026 guidance for the third time, to about $12.6bn, $2.1bn above the original Analyst Day target of $10.5bn. Its Etherlink AI fabric switches now exceed 100 cumulative customers, up from four or five in 2024, and the company targets at least $3.5bn of AI-fabric revenue this year. Multiyear purchase commitments tripled to $9.7bn from $3.6bn, and deferred revenue reached $6.9bn.

What that growth costs shows up one line down. Gross margin fell 232 basis points year over year to 62.9%, inside a 62-64% guide, as hyperscale mix diluted it; operating margin still rose, to 45.4%, because operating income grew 39.7% against revenue's 37.7%. Management says the pricing power to offset mix does not exist yet — backlog is still shipping at prior prices, with structural pricing power pushed to 2027. On the white-box threat, chairperson and chief executive Jayshree Ullal was dismissive: "White box is certainly a tactical solution that we tend to see more in use cases that are simple, scale-up or scale-out where the actual amount of software and system requirements are low," she told investors. Microsoft and Meta were 26% and 16% of 2025 revenue.

Cisco's number is orders, and 40% of it is optics

Cisco booked $9.3bn of hyperscaler AI infrastructure orders in fiscal 2026, about 4.5 times the prior year — but roughly 60% was Silicon One-based systems and 40% Acacia optics, putting switching content nearer $5.6bn. It recognized about $4bn as revenue and guides $7.5bn for fiscal 2027. The same mix that produced the orders erodes the margin: "You should expect a slight gross margin headwind as we move through FY 2027 as we address these very high growth opportunities," chief financial officer Mark Patterson said on the August 12 call.

What the shares earned

Arista's price per dollar of trailing gross profit has moved from roughly 32.5x a year ago to 35.8x while those gross-profit dollars grew 30% — most of its 42.9% twelve-month gain was paid for by profit. Cisco's went from about 7.2x to 10.7x on 11.1% gross-profit growth, so most of its 65.7% year is re-rating, and it now trades at 21.6x forward earnings against roughly 18x in May at a higher share price. The networking group's roughly 11% fall between August 12 and 20, against a 1.2% dip in the S&P 500 tracker and the 30-year Treasury yield's touch of 5.32%, was a de-risking of the whole AI-infrastructure complex rather than a verdict on switching.

The finding is narrower and harder than the drawdown. Arista is compounding, and losing relative ground anyway, because the switching dollar is increasingly sold by whoever sells the accelerator. Ullal's pricing power arrives in 2027, when the old backlog clears and 1.6-terabit Etherlink reaches production. That is also two more years for a bundled fabric to become the default that nobody has to bid.