Does C9500X-28C8D supports 400G to 2x200G?

[josepr]

Can the C9500X-28C8D support splitting a 400G port into 2x200G ports with a module like the QDD-400G-SR8-S?

[Leo Laohoo]

This picture says "8 nonblocking 40/100/200/400G QSFP-DD ports".  

What the picture fails to mention is whether this feature is FCS (first customer ship) or "in the roadmap".  If the answer is "in the roadmap" then I recommend talking to 3rd party optics vendor because they will be able to provide a re-flashed optics to work with the switch.  

[josepr]

Front that statement it doesn't seem like, it looks like it can only downgrade a 400g port to 200g but not split it.

[Leo Laohoo]

SR8 means breakout up to 8 cables.  This means from 400 Gbps to 8 x 50 Gbps. 

SR4 means breakout to 4 cables.  This means from 400 Gbps to 4 x 100 Gbps. 

Cisco's SKU, QDD-400G-SR4.2-BD, breaks out to 4 x100 Gbps.  If Cisco SKU is not (yet) supported then try using 3rd-party brand but I strongly suspect the latest version, 17.11.1, will not support Cisco-branded QDD-400G-SR4.2-BD optics.  For normal accounts, it will take several months (if not years) for any 400 Gbps breakout cables to get software support unless the account happens to be a very big large & important corporate account.