The 100G Ethernet physical layer signalling is moving to PAM4 and using Forward Error Correction (FEC) when the lane signalling rate is greater than 25 Gigabaud (Either 4 lanes x 25 or 2 x 50).
Infiniband EDR uses a signal rate of 25 Gigabaud (Gbd) also and from what I can see HDR uses a rate of 50 Gbd. But Infiniband doesn't use FEC.
What is the difference in signalling that allows Infiniband (IB) to have the same signal rates but doesn't use FEC to reduce error rates. Or does IB just accept higher bit error rates? (Or alternatively is there some other correction in higher layers that allows IB to get away with higher error rates at the physical layer).