Arista executives discuss liquid-cooled networking gear and support for Linear Pluggable Optics to achieve power and cost optimization for AI data centers.
Arista Networks shared some of its plans to deliver liquid-cooled switches and racks that can significantly reduce power consumption in enterprise AI networks.
At Arista’s recent Analyst Day event, co-founder Andreas Bechtolsheim said the company is developing 100% liquid-cooled switches and racks for enterprise data center customers. Liquid cooling saves power because there are no fans, and that reduces vibration, which is better for optics. It delivers between 5% and 10% power savings at the system level, depending on temperature, Bechtolsheim said.
Specifically, Arista is developing an ORv3W-based data center server rack that supports approximately 120 kW of power and can run up to 32 AI fabric switches along with fiber patch panels, management switches and power shelves. The rack supports tight liquid fittings specifically for high-density switch cooling systems.
“A lot of our development is focused in this direction,” Bechtolsheim said. “In addition, we are designing fully liquid-cooled switch racks that offer up to 32 of these fabric switches with patch panels and management switches and power shelves. And again, this is all optimized for the liquid-cooled data center to enable high-density switch configurations.”
Ultimately, AI data centers need liquid-cooled switches, Bechtolsheim said. “This reduces power consumption and failure rates while enabling scale-out networking.”
Bechtolsheim also talked about support for Linear Pluggable Optics, which set up direct links between fiber optic modules, eliminating the need for traditional components such as a Digital Signal Processor. LPO is different from Co-Packaged Optics (CPO), which feature the integration of optical components directly into a switch ASIC.
Both technologies will likely find a role in future AI and optical networks, experts say, as both promise to reduce power consumption and support improved bandwidth density. Both have advantages and disadvantages as well – CPOs are more complex to deploy given the amount of technology included in a CPO package, whereas LPOs promise more simplicity.
Bechtolsheim said that LPO can provide an additional 20% power savings over other optical forms. Early tests show good receiver performance even under degraded conditions, though transmit paths remain sensitive to reflections and crosstalk at the connector level, Bechtolsheim added.
At the recent Hot Interconnects conference, he said: “The path to energy-efficient optics is constrained by high-volume manufacturing,” stressing that advanced optics packaging remains difficult and risky without proven production scale.
“We are nonreligious about CPO, LPO, whatever it is. But we are religious about one thing, which is the ability to ship very high volumes in a very predictable fashion,” Bechtolsheim said at the investor event. “So, to put this in quantity numbers here, the industry expects to ship something like 50 million OSFP modules next calendar year. The current shipment rate of CPO is zero, okay? So going from zero to 50 million is just not possible. The supply chain doesn’t exist. So, even if the technology works and can be demonstrated in a lab, to get to the volume required to meet the needs of the industry is just an incredible effort.”
“We’re all in on liquid cooling to reduce power, eliminating fan power, supporting the linear pluggable optics to reduce power and cost, increasing rack density, which reduces data center footprint and related costs, and most importantly, optimizing these fabrics for the AI data center use case,” Bechtolsheim added.
“So what we call the ‘purpose-built AI data center fabric’ around Ethernet technology is to really optimize AI application performance, which is the ultimate measure for the customer in both the scale-up and the scale-out domains. Some of this includes full switch customization for customers. Other cases, it includes the power and cost optimization. But we have a large part of our hardware engineering department working on these things,” he said.
In the end, Arista is all about standards, said Jayshree Ullal, CEO of Arista, at the investor event.
“If you look at today’s CPO implementations, you got one version from Nvidia, you got another version from Marvell, you got a third version from Broadcom. So that’s what CPC (for co-packaged copper) and pluggable optics give you and deliver all these capabilities richly without locking yourself up into one implementation, which our customers care about. So we’ll embrace them all when they get a little more mature and ready,” Ullal said. At this point, customers aren’t really asking us for them, she said.
“I think a lot of the early CPO interest is still in the trials… The supply chain must catch up. And you know, if the customers get comfortable with it and say, we want it, obviously the rest of the industry is going to get behind it, including us,” Ullal said.
