When it announced its CPO-capable switches, Nvidia said they would improve resiliency by 10 times at scale compared to previous switch generations. Several factors contribute to this claim, including the fact that the optical switches require four times fewer lasers, Shainer says. Whereas the laser source was previously part of the transceiver, the optical engine is now incorporated onto the ASIC, allowing multiple optical channels to share a single laser.
Additionally, in Nvidia’s implementation, the laser source is located outside of the switch. “We want to keep the ability to replace a laser source in case it has failed and needs to be replaced,” he says. “They are completely hot-swappable, so you don’t need to shut down the switch.”
Nonetheless, you may often hear that when something fails in a CPO box, you need to replace the entire box. That may be true if it’s the photonics engine embedded in silicon inside the box. “But they shouldn’t fail that often. There are not a lot of moving parts in there,” Wilkinson says. While he understands the argument around failures, he doesn’t expect it to pan out as CPO gets deployed. “It’s a fallacy,” he says.
There’s also a simple workaround to the resiliency issue, which hyperscalers are already talking about, Karavalas says: overbuild. “Have 10% more ports than you need or 5%,” he says. “If you lose a port because the optic goes bad, you just move it and plug it in somewhere else.”
Which vendors are backing co-packaged optics?
In terms of vendors that have or plan to have CPO offerings, the list is not long, unless you include various component players like TSMC. But in terms of major switch vendors, here’s a rundown:
- Broadcom has been making steady progress on CPO since 2021. It is now shipping “to early access customers and partners” its third-generation offering, the Tomahawk 6 – Davisson (TH6-Davisson). Developed in conjunction with Micas Networks, TSMC, HPE, and others, the TH6-Davisson is an Ethernet switch supporting 102.4T bps of optically enabled switching capacity.
- In March 2025, Nvidia announced new photonics switches that include support for CPO, likewise developed with partners including TSMC. The Nvidia Spectrum-X Photonics switches support a total throughput of 400T bps in various port configurations while the liquid-cooled Nvidia Quantum-X Photonics switches provide 144 ports of 800Gb/s InfiniBand based on 200G bps SerDes. No word yet on exactly when they’ll be shipping other than “next year,” with the InfiniBand models debuting first, according to Shainer.
- Cisco is proceeding cautiously with its optics strategy, apparently due at least in part to the reliability issue. It demoed a CPO switch in 2023 but has yet to make a formal announcement. Bill Gartner, senior vice president and general manager of Cisco’s optical systems and optics business, recently told Network World: “The thing that I think we have to be cautious about as an industry is that CPO package assembly will have 1,000 or more optics connections, and that means fiber attached to pieces of silicon. And I think the industry is going to go through a learning curve of making that a very high yield and very highly reliable.”
How does linear pluggable optics compare to CPO?
Arista, you may have noticed, is absent from that CPO list. It is backing a competing technology, linear pluggable optics (LPO).
