400G OSFP vs QSFP-DD vs QSFP112: Form Factor Guide

OSFP, QSFP-DD and QSFP112 can all appear in 400G networks, but they are different physical and electrical form-factor families. The correct choice starts with the host port, not simply the 400G speed rating. QSFP-DD QSFP-DD is a double-density QSFP form factor using eight electrical lanes and is widely associated with 400GbE switch interfaces. Platform support must be checked on the specific equipment. QSFP112 QSFP112 is a four-lane QSFP form factor designed around higher per-lane signalling for 400G. It should not be assumed interchangeable with QSFP-DD simply because both can carry 400G. OSFP OSFP is a larger form factor with substantial thermal capacity and is used across high-speed AI and data-centre networking. OSFP implementations can differ, so a module should not be assumed to fit or operate in every OSFP host cage. SELECTION CHECKLIST 1. Identify the exact switch, NIC or DPU model and port type. 2. Confirm required speed and protocol. 3. Select the optical standard from reach, fibre and connector requirements. 4. Check whether the link is straight 400G or a breakout architecture. 5. Confirm coding and platform compatibility before ordering. Photon Optics only publishes compatibility where approved evidence is available. Products are manufactured to order with a typical manufacturing and delivery lead time of 2-3 weeks.