Thinking about faster network? Well for optics the main choice is between QSFP-DD and OSFP. QSFP-DD is "Double-Density". It's main advantage is backward compatible to QSFP+/QSFP28/QSFP56. So if that is important make sure your 400G/800G is "-DD". Exactly as -"DD" is backward compatible the advantage of OSFP is that it is NOT backward compatible but can support higher and denser bandwidth. It is designed for future needs. So this is the choice for a network that will grow beyond 800G. What if you have a OSFPslot and a QSFP that you wish to use then of course there are adapters to make OSFP compatible with QSFP-DD. So if there is a rule of what to choose then there is also another path that will complicate the choice between QSFP-DD and OSFP.
