What Is XPO? The Loudest New Scale-Up Standard at OFC 2026, Explained
On the eve of OFC in March 2026, the optical interconnect industry launched three scale-up MSAs at once: OCI, Open CPX, and XPO. All three look like alphabet soup, but they are the banners of three camps fighting over the same territory. The loudest is XPO — backed by Andy Bechtolsheim, Arista co-founder and a heavyweight of Silicon Valley networking.
XPO stands for eXtra-dense Pluggable Optics. In one sentence: it's a form-factor standard for liquid-cooled, ultra-high-density pluggable optical modules. Since AI racks are now fully liquid-cooled, a pluggable module can take a 400W budget plus a cold plate — achieving CPO-class density without soldering the optics into the package as CPO does.
Key specs
12.8T per module (64 × 200G) = eight 1.6T OSFPs.
4x front-panel density, −75% switch rack footprint, 204.8T in a single OpenRack Unit.
48V power, eight MPO-16 connectors; the same paddle card can host 4×1.6T / 2×3.2T / 1×6.4T engines.
Supports DR/FR/LR/SR/ZR, coherent-lite, copper, and RF; liquid cooling only.
At OFC, Bechtolsheim ran numbers that silenced the room: a 1-million-XPU data center needs 128 million scale-up optics, and the industry as a whole needs more than 1 billion a year. His core argument isn't "XPO is better than CPO" but time to volume — nobody can take a new standard from zero to a billion units a year, and XPO covers every medium with a single form factor. At the system level, for a 120,000-GPU data center, XPO can cut network racks from 1,400 to 350.
At this point, XPO sounds like the textbook answer for scale-up. But at the same OFC, Meta quietly took apart XPO's core selling point with 90 million hours of field data — and that is where STT's analysis begins.
That's the summary of key points for this article.
STT's full analysis — why Meta's data undercuts XPO's reliability pitch, why the three MSAs are really a fight for position in the value chain, and why the endgame for scale-up still lies in-package — is available in the paid section.
👉 Subscribe to STT's paid section: Read the full analysis on vocus (in Chinese)
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