Selling networking gear to the companies building artificial-intelligence data centres is turning out to be a high-volume, low-margin trade, and in the space of ten days three of the four largest listed switch vendors said so in their own numbers.

Cisco Systems, the largest maker of enterprise switching, routing, wireless and security equipment, closed its fiscal year on 12 August with revenue of $17.3bn in the quarter, up 18%, and non-GAAP earnings per share of $1.22 against a $1.17 consensus, according to the company's results release. Product orders rose 35%, and 25% even excluding the hyperscale cloud operators, with networking orders up 40% in the quarter. AI infrastructure orders from hyperscalers were $4bn in the quarter and $9.3bn for the year, with $7.5bn of AI revenue expected in fiscal 2027 against the "at least $6bn" guided in May.

The stock fell roughly 8% anyway. Adjusted gross margin came in at 66.3% against 68.4% a year earlier, and management guided fiscal 2027 to about 64.5%, some 150 basis points below Street estimates, on a heavier mix of hardware sold to cloud customers. That is the clearest disclosed evidence yet that the AI buildout buys revenue at the expense of vendor economics.

Arista is growing faster and earning less on each dollar

Arista Networks, which sells high-speed Ethernet switches and its EOS network operating system to internet companies, banks and governments, is the purest expression of the trade. Revenue growth has accelerated four quarters running — 27.5%, 28.9%, 35.1% and 37.7% — to a first $3bn quarter, and on 4 August the company raised full-year guidance a third time, to $12.6bn, $2.1bn above its original Analyst Day target. Its Etherlink AI fabric switches now have more than 100 customers, up from four or five in 2024; multiyear purchase commitments tripled to $9.7bn and deferred revenue reached $6.9bn.

And gross margin fell to 62.93% from 65.25%, with management guiding 62-64% for the year and saying explicitly that it has no pricing power yet because backlog is shipping at old prices. Operating leverage is nonetheless real: operating income grew 39.7% on 37.7% revenue growth, lifting operating margin to 45.4%.

The competitive threat is not white-box hardware, which Arista's management called "tactical". It is NVIDIA, which overtook Arista for the number-one position in data-centre Ethernet switching by revenue in the first quarter of 2026, at 21.5% share against 20.7%, from under 4% two years earlier. The mitigating fact is that the market itself grew 39.8% to $15.4bn, the data-centre slice by 61%. Underneath both sits Broadcom, now shipping its Tomahawk 6 switch chip at 102.4 terabits per second, twice the throughput of the silicon in NVIDIA's Spectrum-X.

HPE leads on the tape; Extreme diverges on the business

Hewlett Packard Enterprise, which sells servers, storage and — since acquiring Juniper Networks — enterprise networking, is the group's leader by every price measure and its most improved business: April-quarter revenue up 40.7%, gross margin up 889 basis points, networking revenue up 148% to $2.7bn with cumulative "networks for AI" orders set to reach $2bn by year-end, two years early. It also booked $1.8bn of new AI system orders, taking the cumulative total to $16.4bn.

Extreme Networks, a $3.1bn maker of campus wired and wireless gear for hospitals, schools and retailers, has no share of that. It beat on the June quarter but guided fiscal 2027 revenue to $1.38-1.40bn, roughly 8-9% growth against the 13% just delivered, blaming in part a shift of service revenue to its Platform ONE subscription. Growth has now decelerated four quarters running and operating margin is 6.2%, against Arista's 45.4% and Cisco's 24.7%.

The two verdicts

On the business: CONFIRMS at Arista, Cisco and HPE on volume — orders, backlog and revenue are all accelerating — but CONTRADICTS on margin at Cisco and Arista alike. CONTRADICTS at Extreme, which is decelerating with no AI attachment.

On valuation it splits. Cisco at 33.8x trailing and 23.7x forward earnings has fallen from 41.6x trailing in May while earnings grew 30% — a de-rating the margin guide justifies. HPE's 17.5x forward is the group's cheapest, but its price-to-gross-profit went from 3.28x in May to 6.19x, an 89% expansion, while consensus models revenue growth slowing from 30.3% this year to 11.2% next. Arista at 24.3x trailing sales sits at the top of its three-month range. Extreme, down 27% in three weeks, trades at 2.45x sales — the same multiple as in early May. Verdict: INCONCLUSIVE, and name-specific.

The tape has already sorted them. HPE's 50-day average has stayed above its 200-day since 23 April, the only unbroken uptrend of the four; Cisco's stepped down on 20 July and Extreme's on 10 August, the latter after single-day falls of 17.4% and 9.0%. The prices agree with the businesses, which is rarer than it sounds.

The setup

Where it stands — AI networking orders are accelerating across three of four vendors while gross margins compress at the two largest. Would confirm — Cisco's fiscal 2027 first-quarter adjusted gross margin printing above the guided 64.5%. Would invalidate — Arista's full-year gross margin falling below the 62-64% guided range, or 2026 guidance cut from $12.6bn. Watch next — HPE's fiscal third-quarter results in early September, including networking segment margin against the low-20s guide. Valuation — Cisco 33.8x trailing, 23.7x forward, versus 41.6x trailing in May; Arista 63.4x and 50.6x.