What is CAN Fd bus?
CAN Fd bus (Controller Area Network with Flexible Datarate) is an extension of CAN bus. This is pretty new, only few devices on the market support it.
Up to 30 nodes could be connected on the same bus with a speed up to 8M bits per second. For higher speed, take a look to CAN
On the same bus, you can mix CAN devices with CAN Fd devices. Normal CAN cannot understand CAN Fd dataframe so they just ignore them.