“What our LPO is doing is benefitting greatly from what’s going on in Silicon One and the software there,” Gartner said. “For customers that especially are deploying Silicon One on both ends of the link, there’s a 30% or 50% power reduction.”
The key technology in Silicon One is its strong support for serializer/deserializer (SerDes) capabilities on its switching ASIC. The new G300 chip found in the 9000 and 8000 boxes features 512 lanes of 200 Gbps SerDes for a total switching capacity of 102.4 Tbps, supporting low-power interconnects with extended reach—500 meters or even 2 kilometers —is important for large-scale AI and GPU clusters, according to Gartner.
Another issue with utilizing LPO technology is the reliability of the optics involved– a topic Cisco has been pushing hard on. In a recent Network World article, Gartner said that Cisco conducted a reliability test for which it acquired 20 different optics from different suppliers. “These were 100G and 400G optics at the time,” and all were compliant with industry standards, and yet “none of those optics passed our stress test,” he said.
Cisco’s testing environments make changes to different conditions, such as the temperature or humidity level, or the voltage level that the optic is seeing on the host, or the skew between the signals coming from the host. “We do all of those things in various combinations,” Gartner said.
While optics might technically comply with industry standards, “what we know is that if they were put into a stressful environment … they wouldn’t perform,” he said, “and so that’s the thing that we’re trying to raise awareness of for our customers.”
Moving forward, other Silicon One-based systems are likely to support LPO modules, Gartner said. And ultimately co-packaged optics (CPO) will also play a big role.
