CAUI‑4 reception on Agilex 5 via GTS PHY IP?

Hi,

When you say 'One source says PCS is not supported above 17.16 Gbps' in your description, can you point us to the document which mentions this?

To answer your question,

Can we implement CAUI‑4 reception manually using GTS PHY IP with PCS enabled?

Ans -> Yes

Is there a soft MAC IP (even licensed) available that supports this 100G aggregation for Agilex 5?

Ans. -> There is no IP that supports 100G aggregation.

Are there any Quartus 25.1 limitations for this mode we should be aware of?

Ans. -> List of current known issues can be found in the following document. Specifically pointing to GTS Ethernet Hard IP related section.

2.1.1.6. Reduced Tx performance on GTS Ethernet FPGA Hard IP for 25GE...

Regards