Arista Posts $3.7B Quarter, Doubles Down on $200B AI Networking TAM

By Amara Osei

Arista Networks booked $3.7 billion in third-quarter revenue, a near-59% jump year over year that blew past its own $3.3 billion guidance. Net income did better still, climbing 83% to nearly $1.6 billion.

Nearly all of that money came from the vendor's scale-across and scale-out platforms. Its scale-up suite, the third leg of the stool, is still waiting in the wings. CEO Jayshree Ullal told analysts the balance between the first two will shift as scale-out starts nibbling at scale-across's share.

"The split this year is roughly 70-30," Ullal said. "The 70 may come down and the 30 would go up when it comes to scale-across because it's a very strong use case for us." She added that scale-across should hold at least a third of the mix, probably more, by 2027.

Why the 'scale' talk matters

Arista's 7800 scale-across platform remains, in Ullal's telling, the differentiated workhorse. "Scale for security, scale for performance, scale for reliability and there's just no room for error when you're connecting millions of XPUs," she said. "We feel very comfortable that these are our two strongest use cases."

The word scale earns its keep here. Operators wiring AI clusters can't tolerate flaky links between millions of accelerators, and that's precisely the job Arista sells into. Growth, for now, rides on those two established use cases.

How fast does Arista expect to grow?

The vendor raised its fiscal 2027 expectations accordingly. Arista now expects up to 40% year-over-year growth in full-year revenue. Within that:

• AI fabric-based revenues should double to $7 billion for the full year
• Campus networking revenue is forecast to grow 60%, reaching $2 billion

To feed that pipeline, Arista raised its supply chain purchase commitments from $9.7 billion in the prior quarter to $11.4 billion in the latest one. That's a $1.7 billion vote of confidence in demand actually materializing. Purchase commitments are cash with consequences; marketing decks are not.

Where does the $200 billion TAM come from?

Arista also lifted its total addressable market estimate to roughly $200 billion. The bump, it says, starts arriving in fiscal 2028 courtesy of its newly unveiled open Ethernet rack-scale architecture, built on the Ethernet for Scale-up Networks (ESUN) initiative.

A handful of large industry names contributed input to the architecture, which is designed to power high-density scale-up and scale-out AI infrastructure. The distinction matters: scale-up connects XPUs inside a rack, scale-out connects racks to each other. Ethernet has historically owned the second job; Arista wants it to own both.

"We expect scale-up trials to begin in 2027, driving Ethernet to larger ratings of 126 to 144 within a rack and across the thousands across racks, with production expected for scale up in 2028," Ullal said.

Commercial reality vs. the TAM pitch

The Q3 numbers are real revenue, booked and counted. The $200 billion TAM, by contrast, is a forecast of a market Arista hopes to contest — standard vendor arithmetic, best taken with a pinch of salt. The gap between the two closes, or doesn't, in 2028 when ESUN-based scale-up production is slated to begin.

For now the story is simpler: AI builders keep buying switches faster than Arista can forecast, and the vendor keeps raising its guidance and its component orders to match. Trials in 2027 and production in 2028 will show whether the scale-up bet converts the TAM slide into invoices.